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Sample records for waste activated bleaching

  1. Enhancement of lipase catalyzed-fatty acid methyl esters production from waste activated bleaching earth by nullification of lipase inhibitors.

    Science.gov (United States)

    Dwiarti, Lies; Ali, Ehsan; Park, Enoch Y

    2010-01-01

    This study sought to identify inhibitory factors of lipase catalyzed-fatty acid methyl esters (FAME) production from waste activated bleaching earth (wABE). During the vegetable oil refinery process, activated bleaching earth (ABE) is used for removing the impure compounds, but adsorbs vegetable oil up to 35-40% as on a weight basis, and then the wABE is discarded as waste material. The impurities were extracted from the wABE with methanol and evaluated by infra-red (IR) spectroscopy, which revealed that some were chlorophyll-plant pigments. The chlorophylls inhibited the lipase during FAME conversion from wABE. The inhibition by a mixture of chlorophyll a and b was found to be competitive. The inhibition of the enzymatic hydrolysis of waste vegetable oil contained in wABE by chlorophyll a alone was competitive, while the inhibition by chlorophyll b alone was non-competitive. Furthermore, the addition of a small amount of alkali nullified this inhibitory effect and accelerated the FAME production rate. When 0.9% KOH (w/w wABE) was added to the transesterification reaction with only 0.05% lipase (w/w wABE), the maximum FAME production rate improved 120-fold, as compared to that without the addition of KOH. The alkali-combined lipase significantly enhanced the FAME production rate from wABE, in spite of the presence of the plant pigments, and even when a lower amount of lipase was used as a catalyst.

  2. Efficient production of fatty acid methyl ester from waste activated bleaching earth using diesel oil as organic solvent.

    Science.gov (United States)

    Kojima, Seiji; Du, Dongning; Sato, Masayasu; Park, Enoch Y

    2004-01-01

    Fatty acid methyl ester (FAME) production from waste activated bleaching earth (ABE) discarded by the crude oil refining industry was investigated using fossil fuel as a solvent in the esterification of triglycerides. Lipase from Candida cylindracea showed the highest stability in diesel oil. Using diesel oil as a solvent, 3 h was sufficient to obtain a yield of approximately 100% of FAME in the presence of 10% lipase from waste ABE. Kerosene was also a good solvent in the esterification of triglycerides embedded in the waste ABE. Fuel analysis showed that the FAME produced using diesel oil as a solvent complied with the Japanese diesel standard and the 10% residual carbon amount was lower than that of FAME produced using other solvents. Use of diesel oil as solvent in the FAME production from the waste ABE simplified the process, because there was no need to separate the organic solvent from the FAME-solvent mixture. These results demonstrate a promising reutilization method for the production of FAME, for use as a biodiesel, from industrial waste resources containing waste vegetable oils.

  3. Lipase-catalyzed biodiesel production from waste activated bleaching earth as raw material in a pilot plant.

    Science.gov (United States)

    Park, Enoch Y; Sato, Masayasu; Kojima, Seiji

    2008-05-01

    The production of fatty acid methyl esters (FAMEs) from waste activated bleaching earth (ABE) discarded by the crude oil refining industry using lipase from Candida cylindracea was investigated in a 50-L pilot plant. Diesel oil or kerosene was used as an organic solvent for the transesterification of triglycerides embedded in the waste ABE. When 1% (w/w) lipase was added to waste ABE, the FAME content reached 97% (w/w) after reaction for 12 h at 25 degrees C with an agitation rate of 30 rpm. The FAME production rate was strongly dependent upon the amount of enzyme added. Mixtures of FAME and diesel oil at ratios of 45:55 (BDF-45) and 35:65 (BDF-35) were assessed and compared with the European specifications for biodiesel as automotive diesel fuel, as defined by pr EN 14214. The biodiesel quality of BDF-45 met the EN 14214 standard. BDF-45 was used as generator fuel, and the exhaust emissions were compared with those of diesel oil. The CO and SO2 contents were reduced, but nitrogen oxide emission increased by 10%. This is the first report of a pilot plant study of lipase-catalyzed FAME production using waste ABE as a raw material. This result demonstrates a promising reutilization method for the production of FAME from industrial waste resources containing vegetable oils for use as a biodiesel fuel.

  4. Bleaching of Neutral Cotton Seed Oil Using Organic Activated Carbon in a Batch System: Kinetics and Adsorption Isotherms

    Directory of Open Access Journals (Sweden)

    Abba Chetima

    2018-03-01

    Full Text Available In the processing of cotton and neem seeds to obtain oil for diverse uses, enormous quantities of seed husk are generated as waste, which when not properly disposed of, poses environmental problems. One way of reducing this waste is to use it for the production of activated carbon (AC for its multiple applications. In this work, activated carbon was produced from cotton and neem seed husks by carbonization followed by acid activation. The prepared ACs were characterized for its porosity and surface properties as well as for its ability to bleach neutral cotton seed oil. The prepared ACs are very efficient in the decoloration process, as they removed about 96–98% of the pigments compared to 98.4% removal with commercial bleaching earth. Temperature had a pronounced effect on the bleaching of neutral cotton seed oil. Maximum adsorption was observed at 60 °C for a contact time of 45 min. The adsorption kinetics were modelled by the intra-particle and the pseudo-second order equations while the adsorption isotherms followed the Langmuir and Freundlich equations. It is concluded that the organic ACs are efficient in pigment removal from neutral cotton seed oil and therefore are potential bleaching agents for the vegetable oil industry.

  5. The effect of light-activation sources on tooth bleaching

    Science.gov (United States)

    Baroudi, Kusai; Hassan, Nadia Aly

    2014-01-01

    Vital bleaching is one of the most requested cosmetic dental procedures asked by patients who seek a more pleasing smile. This procedure consists of carbamide or hydrogen peroxide gel applications that can be applied in-office or by the patient (at-home/overnight bleaching system). Some in-office treatments utilise whitening light with the objective of speeding up the whitening process. The objective of this article is to review and summarise the current literature with regard to the effect of light-activation sources on in-office tooth bleaching. A literature search was conducted using Medline, accessed via the National Library of Medicine Pub Med from 2003 to 2013 searching for articles relating to effectiveness of light activation sources on in-office tooth bleaching. This study found conflicting evidence on whether light truly improve tooth whitening. Other factors such as, type of stain, initial tooth colour and subject age which can influence tooth bleaching outcome were discussed. Conclusions: The use of light activator sources with in-office bleaching treatment of vital teeth did not increase the efficacy of bleaching or accelerate the bleaching. PMID:25298598

  6. Bleaching of cotton fabric with tetraacetylhydrazine as bleach activator for H2O2.

    Science.gov (United States)

    Liu, Kai; Zhang, Xuan; Yan, Kelu

    2018-05-15

    Tetraacetylhydrazine (TH) as bleach activator for H 2 O 2 cotton bleaching was synthesized and characterized by 1 H NMR, 13 C NMR and MS spectra. TH has better solubility than that of TAED. The CIE whiteness index (WI), H 2 O 2 decomposition rate and bursting strength were employed to investigate the performance of H 2 O 2 /TH bleaching system. By addition of TH, WI and H 2 O 2 decomposition rate increased significantly at 70 °C. Bleaching temperature, NaHCO 3 concentration and bleaching time were also discussed in detail and the loss of bursting strength is not clear. By using benzenepentacarboxylic acid (BA) as a fluorescent probe for hydroxyl radical detection, the bleaching process of H 2 O 2 /TH system was investigated. Acetylhydrazine and diacetylhydrazine were also utilized to further confirm the process. In addition, bimolecular decomposition was investigated by using 9,10-dimethylanthracene (DMA) as fluorescent probe of 1 O 2 . Based on these experimental results, the bleaching mechanism of H 2 O 2 /TH system was proposed. Copyright © 2018 Elsevier Ltd. All rights reserved.

  7. Comparison of Tooth Color Change After Bleaching With Conventional and Different Light-Activated Methods.

    Science.gov (United States)

    Shahabi, Sima; Assadian, Hadi; Mahmoudi Nahavandi, Alireza; Nokhbatolfoghahaei, Hanieh

    2018-01-01

    Introduction: The demand for esthetic dental treatments is increasing in recent years mainly due to improved oral hygiene and better maintenance of oral health and teeth in older individuals. Bleaching of discolored anterior teeth is the most popular among esthetic dental treatments. Even individuals with sound teeth and adequate esthetics seek to have whiter teeth in the anterior region. The aim of this study was to evaluate tooth color changes following conventional in-office bleaching techniques compared to light-activated methods using different light sources. Methods: Seventy sound anterior teeth (devoided of caries and/or fracture), extracted for periodontal and orthodontic reasons were selected and allocated to 7 groups: (A) control, (B) conventional bleaching (C) LED-activated bleaching, (D) KTP laser-activated bleaching, (E) diode laser-activated bleaching, (F) Nd:YAG laser-activated bleaching and (G) CO2 laser-activated bleaching. Colorimetric evaluation was carried out before and after treatment using a spectrophotoradiometer. Data were analyzed by one- and two-way analysis of variance (ANOVA) as well as multiple comparison methods. Results: The results showed that all bleaching procedures were effective in reducing the yellowness index. However, the KTP laser-activated bleaching was significantly more effective than the other techniques in 95% confidence level. It was also seen that CO2 laser activated method has outperformed groups E, F and G and the conventional bleaching without light activation was not effective at all and represented similar results with the control group. Furthermore, the groups E and G had almost the same results in decreasing the yellowness index. Conclusion: The results showed that all bleaching techniques were effective however, the KTP laser-activated bleaching was significantly more efficient, closely followed by the CO2 laser-activated bleaching technique.

  8. Optimization of acid-activated bentonites on bleaching of cotton oil

    International Nuclear Information System (INIS)

    Lacin, O.; Sayan, E.; Kirali, E.G.

    2013-01-01

    Bentonites are commonly used adsorbent on bleaching cotton oil to produce edible oil products. Bleaching capacities of neutralized cotton oil were investigated with acid-activated Arguvan and Kursunlu bentonites. Two models for acid activation of the bentonites were developed by using a full factorial experimental design and central composite design. The parameters used to develop these models were contact time, solid to liquid ratio, acid concentration and moisture of bentonite. By using a constrained optimization program, the maximum bleaching capacities of neutralized cotton oil were determined as 99.99% and 48.5% for Arguvan and Kursunlu, respectively. Optimum results showed that Turkish bentonites (especially Arguvan bentonite) have high bleaching ability and they can be used efficiently to bleach neutralized cotton oil by considering the favorable volume weight, capacity of oil adsorbed and filtration rate. (author)

  9. Tooth Whitening And Temperature Rise With Two Bleaching Activation Methods

    International Nuclear Information System (INIS)

    Abu-ElMagd, D. M.; El-Sayad, I. I.; Abd El-Gawad, L. M.

    2009-01-01

    To measure the tooth whitening and the surface and Intrapulpal temperature increase in vitro on freshly extracted upper human central incisors after chemical, Zoom AP light and diode laser activated bleaching. Thirty caries-free upper human incisors were selected. Teeth were divided into three equal groups according to the methods of activation of the bleaching agent (n = 10). A whitening gel containing hydrogen peroxide was applied to the buccal surface of all teeth. Group I was bleached using chemically activated hydrogen peroxide gel, for three applications of 15 min each. Group II was bleached with high intensity advanced power Zoom activation light (Zoom AP), for three applications of 15 min each. Group III was bleached with diode laser activation technique, where the teeth were irradiated with 2 Watt diode laser for three applications of 30 sec each. The whitening degree was assessed using an image analysis system, while temperature rise was recorded using a thermocouple on the external tooth surface and Intrapulpal. The degree of whitening increased significantly in all groups. However, the percentage of whitening was not statistically significantly different between the three groups. In addition, group II showed statistically significant higher mean rise in both surface and pulp temperatures than group I and group III. Chemical bleaching produces the same whitening effect as Zoom AP light and laser, with no surface or pulpal temperature rise. Laser application is faster and produces less surface and pulp temperature increase than Zoom AP light. Diode laser used to activate bleaching gels is not considered dangerous to the vitality of dental pulp using power settings of 2 W.

  10. Clinical and Spectrophotometric Evaluation of LED and Laser Activated Teeth Bleaching.

    Science.gov (United States)

    Lo Giudice, R; Pantaleo, G; Lizio, A; Romeo, U; Castiello, G; Spagnuolo, G; Giudice, G Lo

    2016-01-01

    Auxiliary power sources (LED and laser) are used in in-office teeth bleaching techniques to accelerate the redox reaction of the whitening gel to increase ease of use, to improve comfort and safety, and to decrease the procedure time. The aim this study is to evaluate the efficiency of the teeth whitening procedures performed with hydrogen peroxide and carbamide peroxide, LED or Laser activated. 18 patients, affected by exogenous dyschromia, were treated with a bleaching agent composed by 35% hydrogen peroxide and 10% carbamide peroxide. They were divided into two groups: in the first group the bleaching agent was activated by a LED lamp; in the second group it was activated by a Laser diode lamp. Both groups were subjected to 3 bleaching cycle of 15' each. The chromatic evaluations were performed before and after one week from the treatment, using a chromatic scale and a spectrophotometer. The mean value of pre, post bleaching and follow-up were analyzed using a T-test, with results statistically significant for Pbleaching effectiveness. All patients treated with laser activation complained an increase in dental sensitivity. The use of laser-activating systems did not improve the efficacy of bleaching.

  11. Coral bleaching independent of photosynthetic activity.

    Science.gov (United States)

    Tolleter, Dimitri; Seneca, François O; DeNofrio, Jan C; Krediet, Cory J; Palumbi, Stephen R; Pringle, John R; Grossman, Arthur R

    2013-09-23

    The global decline of reef-building corals is due in part to the loss of algal symbionts, or "bleaching," during the increasingly frequent periods of high seawater temperatures. During bleaching, endosymbiotic dinoflagellate algae (Symbiodinium spp.) either are lost from the animal tissue or lose their photosynthetic pigments, resulting in host mortality if the Symbiodinium populations fail to recover. The >1,000 studies of the causes of heat-induced bleaching have focused overwhelmingly on the consequences of damage to algal photosynthetic processes, and the prevailing model for bleaching invokes a light-dependent generation of toxic reactive oxygen species (ROS) by heat-damaged chloroplasts as the primary trigger. However, the precise mechanisms of bleaching remain unknown, and there is evidence for involvement of multiple cellular processes. In this study, we asked the simple question of whether bleaching can be triggered by heat in the dark, in the absence of photosynthetically derived ROS. We used both the sea anemone model system Aiptasia and several species of reef-building corals to demonstrate that symbiont loss can occur rapidly during heat stress in complete darkness. Furthermore, we observed damage to the photosynthetic apparatus under these conditions in both Aiptasia endosymbionts and cultured Symbiodinium. These results do not directly contradict the view that light-stimulated ROS production is important in bleaching, but they do show that there must be another pathway leading to bleaching. Elucidation of this pathway should help to clarify bleaching mechanisms under the more usual conditions of heat stress in the light. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. PROCESS OPTIMIZATION OF TETRA ACETYL ETHYLENE DIAMINE ACTIVATED HYDROGEN PEROXIDE BLEACHING OF POPULUS NIGRA CTMP

    OpenAIRE

    Qiang Zhao; Junwen Pu; Shulei Mao; Guibo Qi

    2010-01-01

    To enhance the bleaching efficiency, the activator of tetra acetyl ethylene diamine (TAED) was used in conventional H2O2 bleaching. The H2O2/TAED bleaching system can accelerate the reaction rate and shorten bleaching time at relative low temperature, which can reduce the production cost. In this research, the process with hydrogen peroxide activated by TAED bleaching of Populus nigra chemi-thermo mechanical pulp was optimized. Suitable bleaching conditions were confirmed as follows: pulp con...

  13. Influence of bleach activators on the fabric made from cotton (gossypium hamster l.)

    International Nuclear Information System (INIS)

    Asif, H.M.; Iftikhar, M.; Shahbaz, B.

    2013-01-01

    Raw cotton contains various type of trash and most of the impurities are removed during the spinning process but still the cotton fabric coming from the weaving or knitting process always contains some impurities. Some time cotton fabric gets the oil, stains and coloured materials which affect the quality of dyed fabric. Bleaching is a process that eliminates unwanted coloured matters from the fibres, yarn and fabrics. A bleaching agent is a material that lightens or whitens a substrate through chemical action. Hydrogen peroxide is by far the most commonly used oxidative bleaching agent for cotton and its blends, accounting for more than 90 percent of all the bleaching agents. The use of activators to enhance the bleaching performance of hydrogen peroxide for cellulosic materials has gained popularity now a day. In this context the main objectives of this paper are to study the influence of different bleaching activators on cotton fabric and to give implications for textile extension.The results indicate that the activators with different concentrations, along with different concentrations of hydrogen peroxide (H/sub 2/O/sub 2) have significant influence on the bleaching performance of cotton fabric. (author)

  14. Improved pulp bleaching potential of Bacillus subtilis WB800 through overexpression of three lignolytic enzymes from various bacteria.

    Science.gov (United States)

    Ozer, Aysegul; Uzuner, Ugur; Guler, Halil Ibrahim; Ay Sal, Fulya; Belduz, Ali Osman; Deniz, Ilhan; Canakci, Sabriye

    2017-12-29

    A chemical bleaching process of paper pulps gives off excessive amount of chlorinated organic wastes mostly released to environment without exposing complete bioremediaton. Recent alternative and eco-friendly approaches toward pulp bleaching appear more responsive to environmental awareness. Here we report, direct use of a recombinant Bacillus subtilis bacterium for pulp bleaching, endowed with three ligninolytic enzymes from various bacteria. In addition, efficient bleaching performance from glutathione-S-transferase (GST) biocatalyst tested for the first time in pulp bleaching applications was also achieved. Simultaneous and extracellular overproduction of highly active GST, laccase, and lignin peroxidase catalysts were also performed by Bacillus cells. Both enhanced bleaching success and improved delignification rates were identified when enzyme combinations tested on both pine kraft and waste paper pulps, ranging from 69.75% to 79.18% and 60.89% to 74.65%, respectively. Furthermore, when triple enzyme combination applied onto the papers from pine kraft and waste pulps, the best ISO brightness values were identified as 66.45% and 64.67%, respectively. The delignification rates of pulp fibers exposed to various enzymatic bleaching sequences were comparatively examined under SEM. In conclusion, the current study points out that in near future, a more fined-tuned engineering of pulp-colonizing bacteria may become a cost-effective and environmentally friendly alternative to chemical bleaching. © 2017 International Union of Biochemistry and Molecular Biology, Inc.

  15. Temperature variation in pulp chamber during dental bleaching in presence or absence of light activation

    OpenAIRE

    Mollica, Fernanda Brandão; Rocha, Daniel Maranha da; Travassos, Alessandro Caldas; Valera, Marcia Carneiro; Araujo, Maria Amélia Maximo de

    2010-01-01

    PURPOSE: In addition to the chemical damage due to bleaching gels penetration into the pulp during pulp vitality dental bleaching, another possible aggressive factor could be the heat generated by the exothermal oxidation reaction of the bleaching gel, which may also be aggravated by the use of light activation. This study assessed the temperature variation in the pulp chamber in human teeth, using three different bleaching gels with or without LED light activation. METHODS: Thirty human pre-...

  16. Immune defenses of healthy, bleached and diseased Montastraea faveolata during a natural bleaching event.

    Science.gov (United States)

    Mydlarz, Laura D; Couch, Courtney S; Weil, Ernesto; Smith, Garriet; Harvell, C Drew

    2009-11-16

    One prominent hypothesis regarding climate change and scleractinian corals is that thermal stress compromises immune competence. To test this hypothesis we tracked how the immune defenses of bleached, apparently healthy and yellow band disease (YBD) diseased Montastraea faveolata colonies varied with natural thermal stress in southwestern Puerto Rico. Colonies were monitored for 21 mo from the peak of the bleaching event in October 2005 to August 2007. Since sea surface temperature was significantly higher in summer and fall 2005 than 2006, year of collection was used as a proxy for temperature stress, and colony fragments collected in 2005 were compared with those collected in 2006. Mortality rate was high (43% overall) and all colonies (except one) either died or became infected with YBD by August 2007. YBD-infected tissue did not bleach (i.e. expel zooxanthellae) during the 2005 bleaching event, even when healthy tissue of these colonies bleached. Immune activity was assayed by measuring prophenoloxidase (PPO), peroxidase (POX), lysozyme-like (LYS) and antibacterial (AB) activity. Immune activity was variable between all coral samples, but there was a significant elevation of PPO activity in bleached colonies collected in 2005 relative to apparently healthy and YBD-diseased corals in 2006. In YBD-diseased colonies, LYS and AB activity were elevated in both healthy and infected tissue, indicating a systemic response; activity levels in these colonies were higher compared to those that appeared healthy. In both these immune parameters, there was a trend for suppression of activity in corals that were bleached in 2005. These data, while complicated by between-genet variability, illustrate the complex interaction between disease and temperature stress on immune function.

  17. Kraft pulp bleaching with molybdenum activated acid peroxide (PMo stage)

    International Nuclear Information System (INIS)

    Rabelo, Marcos Sousa

    2009-01-01

    Optimum conditions to run the P Mo stage for bleaching eucalyptus kraft pulp were 90 deg C, pH 3.5, 2 h, 0.1 kg/t Mo and 5 kg/t H 2 O 2 . The P Mo stage efficiency increased with decreasing pH (1.5-5.5) and increasing temperature (75-90 deg C), time (2-4 h), and hydrogen peroxide (3-10 kg/t) and molybdenum concentration (0.1-0.4 kg/t). The implementation of the P Mo stage, as replacement for the A stage, decreased total active chlorine demand of the OAZDP sequence by 6 kg/t to reach 90% ISO, both in laboratory and mill scale. Such practice resulted in decreased bleaching chemical costs to produce fully bleached pulp of 90% ISO. (author)

  18. Two-state model of light induced activation and thermal bleaching of photochromic glasses: theory and experiments

    International Nuclear Information System (INIS)

    Ferrari, Jose A.; Perciante, Cesar D.

    2008-01-01

    The behavior of photochromic glasses during activation and bleaching is investigated. A two-state phenomenological model describing light-induced activation (darkening) and thermal bleaching is presented. The proposed model is based on first-order kinetics. We demonstrate that the time behavior in the activation process (acting simultaneously with the thermal fading) can be characterized by two relaxation times that depend on the intensity of the activating light. These characteristic times are lower than the decay times of the pure thermal bleaching process. We study the temporal evolution of the glass optical density and its dependence on the activating intensity. We also present a series of activation and bleaching experiments that validate the proposed model. Our approach may be used to gain more insight into the transmittance behavior of photosensitive glasses, which could be potentially relevant in a broad range of applications, e.g., real-time holography and reconfigurable optical memories

  19. Rhythmic ganglion cell activity in bleached and blind adult mouse retinas.

    Science.gov (United States)

    Menzler, Jacob; Channappa, Lakshmi; Zeck, Guenther

    2014-01-01

    In retinitis pigmentosa--a degenerative disease which often leads to incurable blindness--the loss of photoreceptors deprives the retina from a continuous excitatory input, the so-called dark current. In rodent models of this disease this deprivation leads to oscillatory electrical activity in the remaining circuitry, which is reflected in the rhythmic spiking of retinal ganglion cells (RGCs). It remained unclear, however, if the rhythmic RGC activity is attributed to circuit alterations occurring during photoreceptor degeneration or if rhythmic activity is an intrinsic property of healthy retinal circuitry which is masked by the photoreceptor's dark current. Here we tested these hypotheses by inducing and analysing oscillatory activity in adult healthy (C57/Bl6) and blind mouse retinas (rd10 and rd1). Rhythmic RGC activity in healthy retinas was detected upon partial photoreceptor bleaching using an extracellular high-density multi-transistor-array. The mean fundamental spiking frequency in bleached retinas was 4.3 Hz; close to the RGC rhythm detected in blind rd10 mouse retinas (6.5 Hz). Crosscorrelation analysis of neighbouring wild-type and rd10 RGCs (separation distance rhythmic RGC spiking in these retinas is driven by a network of presynaptic neurons. The inhibition of glutamatergic ganglion cell input or the inhibition of gap junctional coupling abolished the rhythmic pattern. In rd10 and rd1 retinas the presynaptic network leads to local field potentials, whereas in bleached retinas additional pharmacological disinhibition is required to achieve detectable field potentials. Our results demonstrate that photoreceptor bleaching unmasks oscillatory activity in healthy retinas which shares many features with the functional phenotype detected in rd10 retinas. The quantitative physiological differences advance the understanding of the degeneration process and may guide future rescue strategies.

  20. Recovery of Spent Bleaching Earth From Palm Oil Refining Using Radiation

    International Nuclear Information System (INIS)

    Nor Azillah Fatimah Othman; Tuan Amran Tuan Abdullah; Nor Azillah Fatimah Othman; Nor Azwin Shukri; Selambakkanu, S.; Siti Fatahiyah Mohamad

    2014-01-01

    Acid activated calcium montmorillonite clay or commonly referred to as bleaching clays is one type of clay used in physical refining of palm oil and it is prioritized in removing a variety of undesirable impurities which would otherwise impart colour, odour and taste to the refined product. Used-up bleaching clays or known as Spent Bleaching Earth (SBE) is considered as industrial waste and commonly dispose without any pretreatment. SBE usually contains considerable quantities of entrained oil that is quantified approximately to 30 to 40 %. The residual oil in these principal solid waste products can rapidly oxidize to the point of spontaneous ignition as a result of clay-catalyzed auto-oxidation reactions. Due to this fact, the disposal of SBE has become an environmental problem and pretreatment of SBE is very important. There are several studies on the residual oil removal from the SBE using heat treatment. Radiation generated from electron beam accelerator can supply high energy to break the C-C and C-H bond. It is expected that the removal of hydrocarbon will occurs at high rate compared to conventional heating. This research proposes the use of radiation on the recovery of SBE from palm oil refining waste. Evaluation of radiation effect on properties of SBE will be conducted to study the effectiveness of using radiation in the purification process. Finally, the material produced will be evaluated and characterized for regeneration and reuse purpose. (author)

  1. Physicochemical properties and oxidative stability of bleached pomace-olive oil on Tunisian activated clays

    International Nuclear Information System (INIS)

    Jahouach, Wafa

    2002-01-01

    This work is a contribution to studying bleaching process, which is an important stage in refining of vegetable oils. This process permitted to reduce or convert undesired constituents to harmless ones from oils and fats. Virgin olive oil, considered as reference, and pomace-olive oil were bleached in optimal conditions using Tunisian activated clays ( collected from the South of Tunisia) which were prepared in our laboratory and compared with commercial bleaching earths. It was shown that activated Tunisian clays are characterized by a very important adsorptive capacity, which is similar to that of commercial ones. In addition, the study of physicochemical properties of bleached oils was considered. The fatty acid composition (GC), the triacylglycerol composition (HPLC), and oxidative stability (UV spectrometry) allowed to conclude that treated oils do not undergo considerable physicochemical alterations and their caracteristics remain in concordance with international standards relative to edible refined oils. (Author)

  2. Effect of bleaching on mercury release from amalgam fillings and antioxidant enzyme activities: a pilot study.

    Science.gov (United States)

    Cakir, Filiz Yalcin; Ergin, Esra; Gurgan, Sevil; Sabuncuoglu, Suna; Arpa, Cigdem Sahin; Tokgoz, İlknur; Ozgunes, Hilal; Kiremitci, Arlin

    2015-01-01

    The aim of this pilot clinical study was to determine the mercury release from amalgam fillings and antioxidant enzyme activities (Superoxide Dismutase [SOD] and Catalase[CAT] ) in body fluids after exposure to two different vital tooth bleaching systems. Twenty eight subjects with an average age of 25.6 years (18-41) having at least two but not more than four Class II amalgam fillings on each quadrant arch in the mouth participated in the study. Baseline concentrations of mercury levels in whole blood, urine, and saliva were measured by a Vapor Generation Accessory connected to an Atomic Absorption Spectrometer. Erythrocyte enzymes, SOD, and CAT activities in blood were determined kinetically. Subjects were randomly assigned to two groups of 14 volunteers. Group 1 was treated with an at-home bleaching system (Opalescence PF 35% Carbamide Peroxide, Ultradent), and Group 2 was treated with a chemically activated office bleaching system (Opalescence Xtra Boost 38% Hydrogen Peroxide, Ultradent) according to the manufacturer's recommendations. Twenty-four hours after bleaching treatments, concentrations of mercury and enzymes were remeasured. There were no significant differences on mercury levels in blood, urine, and saliva before and after bleaching treatments (p > 0.05). No differences were also found in the level of antioxidant enzyme activities (SOD and CAT) before and after treatments (p > 0.05). Mercury release did not affect the enzyme activities (p > 0.05). Bleaching treatments either office or home did not affect the amount of mercury released from amalgam fillings in blood, urine, and saliva and the antioxidant-enzyme activities in blood. Bleaching treatments with the systems tested in this pilot study have no deleterious effect on the mercury release from amalgam fillings and antioxidant enzymes in body fluids. © 2014 Wiley Periodicals, Inc.

  3. Radiation coloration and bleaching of glass

    International Nuclear Information System (INIS)

    Treadaway, M.J.; Passenheim, B.C.; Kitterer, B.D.; Schall, P.

    1976-01-01

    The results of an investigation of the bleaching of radiation-induced darkening in ten Schott optical glasses is presented. Measurements were made at several temperatures from 160K to 340K for times from 5 msec to 500 hours after exposure. The theory of processes distributed in activation energies has been used to formulate a model which explains the time and temperature dependence of the bleaching. Analysis of the bleaching results in terms of this model has yielded the activation energy distributions and ''frequency factors'' which govern the bleaching for each material

  4. Patterns of coral bleaching: Modeling the adaptive bleaching hypothesis

    Science.gov (United States)

    Ware, J.R.; Fautin, D.G.; Buddemeier, R.W.

    1996-01-01

    Bleaching - the loss of symbiotic dinoflagellates (zooxanthellae) from animals normally possessing them - can be induced by a variety of stresses, of which temperature has received the most attention. Bleaching is generally considered detrimental, but Buddemeier and Fautin have proposed that bleaching is also adaptive, providing an opportunity for recombining hosts with alternative algal types to form symbioses that might be better adapted to altered circumstances. Our mathematical model of this "adaptive bleaching hypothesis" provides insight into how animal-algae symbioses might react under various circumstances. It emulates many aspects of the coral bleaching phenomenon including: corals bleaching in response to a temperature only slightly greater than their average local maximum temperature; background bleaching; bleaching events being followed by bleaching of lesser magnitude in the subsequent one to several years; higher thermal tolerance of corals subject to environmental variability compared with those living under more constant conditions; patchiness in bleaching; and bleaching at temperatures that had not previously resulted in bleaching. ?? 1996 Elsevier Science B.V. All rights reserved.

  5. Sludge disinfection by combined treatment of bleaching powder and irradiation

    International Nuclear Information System (INIS)

    Harsoyo

    1987-01-01

    Sludge disinfection by combined treatment of bleaching powder and irradiation. Disinfection of sludge by combined treatment of bleaching powder and irradiation has been investigated. Sludge were obtained from water and waste sanitation department (Dinas Kebersihan) DKI located at Kebon Nanas, Jakarta. Sludge were mixed with bleaching powder at the concentration of 0, 10 and 20 mg/l and then irradiated in multipurpose panoramic batch irradiator (PANBIT) with doses of 2, 4, 6, 8, and 10 kGy and a dose rate 9 kGy/h. The reducing colony form unit caused by the combined treatment depend on type bacteria observed in sludge. Pathogenic bacteria as Clostridium still survive at a dose of 10 kGy on sludge containing 20 mg/l bleaching powder, but Salmonella, Shigella, and Vibrio were not detected in this experiment, neither in the control nor in the irradiated samples. (author). 14 refs.; 4 figs

  6. Effects of different activation processes on H2O2/TAED bleaching of Populus nigra chemi-thermo mechanical pulp

    OpenAIRE

    Qiang Zhao; Dezhi Sun; Zhaohong Wang; Junwen Pu; Xiaojuan Jin; Mian Xing

    2012-01-01

    Tetra acetyl ethylene diamine (TAED) was used as an activator in H2O2 bleaching to improve bleaching efficiency. The present work was aimed at confirming different activations for various H2O2/TAED bleaching processes, including the addition of acetic anhydride and the step-addition of sodium hydroxide. The results showed that an acetic anhydride dosage of 1%, an acetic anhydride treatment time of 10 min, and an addition time of 45 min were the optimal treatment conditions. The optimum proces...

  7. Adsorption studies on bleaching of palm-kernel oil with activated ...

    African Journals Online (AJOL)

    Adsorption studies were performed on bleaching of palm-kernel oil (PKO) with different weight ratios of activated bentonite clay/PKO, ranging from 0.25% to 3% and at different temperatures of 70ºC, 80ºC, 90ºC and 100ºC. The equilibrium data generated were subsequently fitted with Langmuir and Freundlich adsorption ...

  8. Reef corals bleach to resist stress.

    Science.gov (United States)

    Obura, David O

    2009-02-01

    A rationale is presented here for a primary role of bleaching in regulation of the coral-zooxanthellae symbiosis under conditions of stress. Corals and zooxanthellae have fundamentally different metabolic rates, requiring active homeostasis to limit zooxanthellae production and manage translocated products to maintain the symbiosis. The control processes for homeostasis are compromised by environmental stress, resulting in metabolic imbalance between the symbionts. For the coral-zooxanthella symbiosis the most direct way to minimize metabolic imbalance under stress is to reduce photosynthetic production by zooxanthellae. Two mechanisms have been demonstrated that do this: reduction of the chlorophyll concentration in individual zooxanthellae and reduction of the relative biomass of zooxanthellae. Both mechanisms result in visual whitening of the coral, termed bleaching. Arguments are presented here that bleaching provides the final control to minimize physiological damage from stress as an adversity response to metabolic imbalance. As such, bleaching meets the requirements of a stress response syndrome/general adaptive mechanism that is sensitive to internal states rather than external parameters. Variation in bleaching responses among holobionts reflects genotypic and phenotypic differentiation, allowing evolutionary change by natural selection. Thus, reef corals bleach to resist stress, and thereby have some capacity to adapt to and survive change. The extreme thermal anomalies causing mass coral bleaching worldwide lie outside the reaction norms for most coral-zooxanthellae holobionts, revealing the limitations of bleaching as a control mechanism.

  9. Color Recovery Effect of Different Bleaching Systems on a ...

    African Journals Online (AJOL)

    Composite samples were immersed in coffee and turnip juice for 1 week in each. One laser activated bleaching (LB) (Biolase Laserwhite*20) and three conventional bleaching systems (Ultradent Opalescence Boost 40% (OB), Ultradent Opalescence PF 15% home bleaching (HB), Crest 3D White [Whitening Mouthwash]) ...

  10. Microtensile bond strength of enamel after bleaching.

    Science.gov (United States)

    Lago, Andrea Dias Neves; Garone-Netto, Narciso

    2013-01-01

    To evaluate the bond strength of a composite resin to the bovine enamel bleached with 35% hydrogen peroxide. It was used an etching-and-rinse adhesive system employed immediately, 7 and 14 days after the bleaching. Twenty bovine teeth were randomly distributed into 4 groups (n = 5), 3 experimental and 1 control. G1: Unbleached + restoration 14 days after storage in artificial saliva (control); G2: Bleached + restoration immediately after bleaching; G3: Bleached + restoration 7 days after bleaching; G4: Bleached + restoration 14 days after bleaching. Their buccal enamel surfaces were flattened, and a 25 mm² (5 × 5 mm) area from each one of these regions was outlined so as to standardize the experimental region. Universal hybrid composite resin Filtek™Z350 was inserted into four layers of 1 mm each and photo-activated. The bond strength was quantitatively evaluated by a microtensile test (1.0 mm/min) 24 h after the restorative procedures. The failure mode was assessed through scanning electron microscopy (SEM). There was a significant reduction in the bond strength of the restored teeth immediately after the bleaching (G2). There were no significant differences in enamel bond strength between groups G1, G3, and G4. There was a predominance of adhesive and mixed (cohesive + adhesive) failure in all groups. The 7-day-period after the end of the bleaching with 35% hydrogen peroxide was enough to achieve the appropriate values of bond strength to the enamel.

  11. Increased riboflavin production from activated bleaching earth by a mutant strain of Ashbya gossypii.

    Science.gov (United States)

    Tajima, Satoshi; Itoh, Yoko; Sugimoto, Takashi; Kato, Tatsuya; Park, Enoch Y

    2009-10-01

    The production of riboflavin from vegetable oil was increased using a mutant strain of Ashbya gossypii. This mutant was generated by treating the wild-type strain with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Riboflavin production was 10-fold higher in the mutant compared to the wild-type strain. The specific intracellular catalase activity after 3 d of culture was 6-fold higher in the mutant than in the wild-type strain. For the mutant, riboflavin production in the presence of 40 mM hydrogen peroxide was 16% less than that in the absence of hydrogen peroxide, whereas it was 56% less for the wild-type strain. The isocitrate lyase (ICL) activity of the mutant was 0.26 mU/mg of protein during the active riboflavin production phase, which was 2.6-fold higher than the wild-type strain. These data indicate that the mutant utilizes the carbon flux from the TCA cycle to the glyoxylate cycle more efficiently than the wild-type strain, resulting in enhanced riboflavin production. This novel mutant has the potential to be of use for industrial-scale riboflavin production from waste-activated bleaching earth (ABE), thereby transforming a useless material into a valuable bioproduct.

  12. Microhardness of demineralized enamel following home bleaching and laser-assisted in office bleaching

    Science.gov (United States)

    Ghanbarzadeh, Majid; Akbari, Majid; Hamzei, Haniye

    2015-01-01

    Background There is little data regarding the effect of tooth whitening on microhardness of white spot lesions. This study was conducted to investigate the effect of home-bleaching and laser-assisted in-office bleaching on microhardness of demineralized enamel. Material and Methods Forty bovine incisors were selected and immersed in a demineralizing solution for 12 weeks to induce white spot lesions. Enamel blocks were prepared and randomly assigned to two groups of 20 each. The first group underwent home bleaching with 15% carbamide peroxide which was applied for 8 hours a day over a period of 15 days. In the second group, in-office bleaching was performed by 40% hydrogen peroxide and powered by irradiation from an 810 nm gallium-aluminum-arsenide (GaAlAs) diode laser (CW, 2W). This process was performed for 3 sessions every seven days, in 15 days. The specimens were stored in Fusayama Meyer artificial saliva during the experiment. Surface microhardness was assessed before and after the bleaching therapies in both groups. Results Microhardness decreased significantly following both home bleaching and laser-assisted in-office bleaching (pTooth whitening through home bleaching or laser-assisted in-office bleaching can result in a significant reduction in microhardness of white spot lesions. Therefore, it is suggested to take protective measures on bleached demineralized enamel. Key words:White spot lesion, bleaching, laser, microhardness, demineralized enamel, home bleaching, in-office bleaching. PMID:26330939

  13. Microtensile bond strength of enamel after bleaching

    Directory of Open Access Journals (Sweden)

    Andréa Dias Neves Lago

    2013-01-01

    Full Text Available Objective: To evaluate the bond strength of a composite resin to the bovine enamel bleached with 35% hydrogen peroxide. It was used an etching-and-rinse adhesive system employed immediately, 7 and 14 days after the bleaching. Materials and Methods: Twenty bovine teeth were randomly distributed into 4 groups (n = 5, 3 experimental and 1 control. G1: Unbleached + restoration 14 days after storage in artificial saliva (control; G2: Bleached + restoration immediately after bleaching; G3: Bleached + restoration 7 days after bleaching; G4: Bleached + restoration 14 days after bleaching. Their buccal enamel surfaces were flattened, and a 25 mm² (5 × 5 mm area from each one of these regions was outlined so as to standardize the experimental region. Universal hybrid composite resin Filtek™Z350 was inserted into four layers of 1 mm each and photo-activated. The bond strength was quantitatively evaluated by a microtensile test (1.0 mm/min 24 h after the restorative procedures. The failure mode was assessed through scanning electron microscopy (SEM. Results: There was a significant reduction in the bond strength of the restored teeth immediately after the bleaching (G2. There were no significant differences in enamel bond strength between groups G1, G3, and G4. There was a predominance of adhesive and mixed (cohesive + adhesive failure in all groups. Conclusion: The 7-day-period after the end of the bleaching with 35% hydrogen peroxide was enough to achieve the appropriate values of bond strength to the enamel.

  14. Therapeutic effectiveness of a new enzymatic bleaching dentifrice.

    Science.gov (United States)

    Forner, Leopaldo; Amengual, José; Liena, Carmen; Riutord, Pere

    2012-01-01

    Research into bleaching focuses on new products in order to minimize undesirable effects. This study evaluated the bleaching effectiveness of a new enzymatic-activated dentifrice. A total of 20 volunteers were bleached with a dentifrice containing 5% lactoperoxidase and 3% carbamide peroxide applied three times a day for two minutes over 21 days. Color was recorded before and after the treatment using a spectrophotometer. CIELAB differences were calculated before and after treatment using the paired t test (P whitening teeth. Enzymatic dental bleaching is able to increase the efficiency of low concentration peroxides, reducing the potential risk of peroxides on oral tissues.

  15. Efficacy of cold light bleaching using different bleaching times and their effects on human enamel.

    Science.gov (United States)

    Wang, Wei; Zhu, Yuhe; Li, Jiajia; Liao, Susan; Ai, Hongjun

    2013-01-01

    This study investigated the efficacy of cold light bleaching using different bleaching times and the effects thereof on tooth enamel. Before and after bleaching, stained tooth specimens were subjected to visual and instrumental colorimetric assessments using Vita Shade Guide and spectrophotometric shade matching. Enamel surface alterations were examined using scanning electron microscopy (SEM) to analyze surface morphology, surface microhardness (SMH) measurement to determine changes in mechanical properties, and X-ray diffraction (XRD) to characterize post-bleaching enamel composition. Cold light bleaching successfully improved tooth color, with optimal efficacy when bleaching time was beyond 10 min. Significant differences in surface morphology were observed among the different bleaching times, but no significant differences were observed for enamel composition and surface microhardness among the different bleaching times. Results of this study revealed an association between the bleaching time of cold light bleaching and its whitening efficacy. Together with the results on enamel surface changes, this study provided positive evidence to support cold light bleaching as an in-office bleaching treatment.

  16. Improvement in rice straw pulp bleaching effluent quality by incorporating oxygen delignification stage prior to elemental chlorine-free bleaching.

    Science.gov (United States)

    Kaur, Daljeet; Bhardwaj, Nishi K; Lohchab, Rajesh Kumar

    2017-10-01

    Environmental degradation by industrial and other developmental activities is alarming for imperative environmental management by process advancements of production. Pulp and paper mills are now focusing on using nonwood-based raw materials to protect forest resources. In present study, rice straw was utilized for pulp production as it is easily and abundantly available as well as rich in carbohydrates (cellulose and hemicelluloses). Soda-anthraquinone method was used for pulp production as it is widely accepted for agro residues. Bleaching process during paper production is the chief source of wastewater generation. The chlorophenolic compounds generated during bleaching are highly toxic, mutagenic, and bioaccumulative in nature. The objectives of study were to use oxygen delignification (ODL) stage prior to elemental chlorine-free (ECF) bleaching to reduce wastewater load and to study its impact on bleached pulp characteristics. ODL stage prior to ECF bleaching improved the optical properties of pulp in comparison to only ECF bleaching. When ODL stage was incorporated prior to bleaching, the tensile index and folding endurance of the pulp were found to be 56.6 ± 1.5 Nm/g and 140, respectively, very high in comparison to ECF alone. A potential reduction of 51, 57, 43, and 53% in BOD 3 , COD, color, and AOX, respectively was observed on adding the ODL stage compared to ECF only. Generation of chlorophenolic compounds was reduced significantly. Incorporation of ODL stage prior to bleaching was found to be highly promising for reducing the toxicity of bleaching effluents and may lead to better management of nearby water resources. Graphical abstract ᅟ.

  17. Multifocal ERG reveals long distance effects of a local bleach in the retina.

    Science.gov (United States)

    Kretschmann, U; Tornow, R P; Zrenner, E

    1998-06-01

    To examine the distribution of ERG-activity in the central visual field after local bleaching of the fovea, multifocal electroretinograms were recorded in eight normal volunteers before, during and after recurrent light exposure. During bleaching (90% bleached pigment), the response density (scalar product) of the foveal area (0-2 degrees eccentricity) decreased from 10.7 +/- 3.5 to 4.1 +/- 1.9 nV/degree2 (P < 0.001). The average activity in the extrafoveal macular area was unchanged, while the amplitudes were frequently (in 53 of 54 areas) enhanced at 5-30.5 degrees eccentricity. Here the average response density changed from 3.1 +/- 0.9 to 3.5 +/- 1.0 nV/degree2 (P < 0.001). A fast recovery of foveal responses after cessation of bleaching occurred. Besides a strong decrease of response in the directly bleached area, local bleaching led to enhanced activity mainly 3-27 degrees distant from the bleached area.

  18. Non-bleached colonies of massive Porites may attract fishes for selective grazing during mass bleaching events

    Directory of Open Access Journals (Sweden)

    Eri Ikeuchi

    2017-06-01

    Full Text Available In this study we investigated the variation in grazing scar densities between bleached and non-bleached colonies of massive Porites species in Sekisei Lagoon (Okinawa, southwestern Japan during a mass bleaching event in 2016. The grazing scar densities and bleaching susceptibility varied among neighboring colonies of massive Porites spp. However, non-bleached colonies had significantly more surface scars than bleached colonies. One explanation for these variations is that corallivorous fishes may selectively graze on non-bleached, thermally tolerant colonies. This is the first report of a relationship between grazing scars and the bleaching status of massive Porites spp. colonies during a mass bleaching event.

  19. New Insights on Degumming and Bleaching Process Parameters on The Formation of 3-Monochloropropane-1,2-Diol Esters and Glycidyl Esters in Refined, Bleached, Deodorized Palm Oil.

    Science.gov (United States)

    Sim, Biow Ing; Muhamad, Halimah; Lai, Oi Ming; Abas, Faridah; Yeoh, Chee Beng; Nehdi, Imededdine Arbi; Khor, Yih Phing; Tan, Chin Ping

    2018-04-01

    This paper examines the interactions of degumming and bleaching processes as well as their influences on the formation of 3-monochloropropane-1,2-diol esters (3-MCPDE) and glycidyl esters in refined, bleached and deodorized palm oil by using D-optimal design. Water degumming effectively reduced the 3-MCPDE content up to 50%. Acid activated bleaching earth had a greater effect on 3-MCPDE reduction compared to natural bleaching earth and acid activated bleaching earth with neutral pH, indicating that performance and adsorption capacities of bleaching earth are the predominant factors in the removal of esters, rather than its acidity profile. The combination of high dosage phosphoric acid during degumming with the use of acid activated bleaching earth eliminated almost all glycidyl esters during refining. Besides, the effects of crude palm oil quality was assessed and it was found that the quality of crude palm oil determines the level of formation of 3-MCPDE and glycidyl esters in palm oil during the high temperature deodorization step of physical refining process. Poor quality crude palm oil has strong impact towards 3-MCPDE and glycidyl esters formation due to the intrinsic components present within. The findings are useful to palm oil refining industry in choosing raw materials as an input during the refining process.

  20. Cementing Material From Rice Husk-Broken Bricks-Spent Bleaching Earth-Dried Calcium Carbide Residue

    Directory of Open Access Journals (Sweden)

    Muthengia Jackson Washira

    2012-10-01

    Full Text Available A cementious material, coded CSBR (Carbide residue Spent bleaching earth Broken bricks and Rice husks, was made from dried calcium carbide residue (DCCR and an incinerated mix of rice husks (RH, broken bricks (BB and spent bleaching earth (SBE. Another material, coded SBR (Spent bleaching earth Broken bricks and Rice husk ash, was made from mixing separately incinerated RH, SBE and ground BB in the same ash ratio as in CSBR. When CSBR was inter-ground with Ordinary Portland Cement (OPC, it showed a continued decrease in Ca(OH2 in the hydrating cement as a function of curing time and replacement levels of the cement. Up to 45 % replacement of the OPC by CSBR produced a Portland pozzolana cement (PPC material that passed the relevant Kenyan Standard. Incorporation of the CSBR in OPC reduces the resultant calcium hydroxide from hydrating Portland cement. The use of the waste materials in production of cementitious material would rid the environment of wastes and lead to production of low cost cementitious material.

  1. Effect of a New Bleaching Gel on Tooth Whitening.

    Science.gov (United States)

    Barry, T N; Bailey, C W; Ashcraft-Olmscheid, D; Vandewalle, K S

    The purpose of this study was to compare the whitening efficacy of a novel bleaching agent containing a unique tribarrel hydremide-peroxide gel (KöR) with a traditional bleaching system of hydrogen peroxide or carbamide peroxide (Opalescence). Bovine incisors were mounted into a custom resin, arch-shaped mounting device. Four groups of 10 teeth were created using mounting devices containing five teeth each. The in-office and home bleaching gels of KöR and Opalescence were applied to the teeth alone and in trays to simulate a combination of in-office and home bleaching or home bleaching only. Spectrophotometer readings of L* a* b* were performed at baseline, the end of active bleaching (immediate), and three and six months postbleaching. Immediately postbleaching, the use of Opalescence gel resulted in greater change in ΔE* and Δb* (less yellow) for combined and home bleaching techniques compared with KöR. After six months, Opalescence had significantly greater ΔE* and Δb* compared with KöR for home bleaching only. There was no significant difference in ΔL* between Opalescence and KöR at any time period with either technique.

  2. Peroxy bleaches

    Energy Technology Data Exchange (ETDEWEB)

    Carson, P.A. [Unilever Research, Port Sunlight Laboratory (United States) and Chemistry Department, University of Manchester, Institute of Science and Technology (United States)]. E-mail: pcarson2005@aol.com; Fairclough, C.S. [Unilever Research, Port Sunlight Laboratory (United States); Mauduit, C. [Chemistry Department, University of Manchester, Institute of Science and Technology (United States); Colsell, M. [Chemistry Department, University of Manchester, Institute of Science and Technology (United States)

    2006-08-25

    Fabric laundering is now a sophisticated chemical process involving a variety of operations including bleaching. The chemistry of peroxy bleaches is described including the use of novel organic compounds to provide effective bleaching at the lower temperatures of modern wash cycles. The instability of peroxy compounds is illustrated using cameo case histories to relate theory and practice. Techniques available for determining their thermochemistry are summarised. A model is provided for hazard and risk assessment of development projects in general (particularly those involving new molecules, processes or formulations) from ideas phase through exploratory laboratory investigations to pilot plant scale-up and eventual manufacture and commercial exploitation. This paper is a prelude to Part 2, which describes the determination of thermodynamic and kinetic properties of peroxy bleaches and discusses the implication of the results in terms of precautions for their safe storage and incorporation into detergent formulations during processing.

  3. Peroxy bleaches

    International Nuclear Information System (INIS)

    Carson, P.A.; Fairclough, C.S.; Mauduit, C.; Colsell, M.

    2006-01-01

    Fabric laundering is now a sophisticated chemical process involving a variety of operations including bleaching. The chemistry of peroxy bleaches is described including the use of novel organic compounds to provide effective bleaching at the lower temperatures of modern wash cycles. The instability of peroxy compounds is illustrated using cameo case histories to relate theory and practice. Techniques available for determining their thermochemistry are summarised. A model is provided for hazard and risk assessment of development projects in general (particularly those involving new molecules, processes or formulations) from ideas phase through exploratory laboratory investigations to pilot plant scale-up and eventual manufacture and commercial exploitation. This paper is a prelude to Part 2, which describes the determination of thermodynamic and kinetic properties of peroxy bleaches and discusses the implication of the results in terms of precautions for their safe storage and incorporation into detergent formulations during processing

  4. Color Recovery Effect of Different Bleaching Systems on a ...

    African Journals Online (AJOL)

    2017-12-05

    Dec 5, 2017 ... KEYWORDS: Composite resin, discoloration, home bleaching, laser activated bleaching, office ... hexametaphosphate, which protect the teeth surface from .... exposure, saliva and other fluids diluting the staining .... Penetration of the pulp ... dentin permeability of carbamide peroxide and hydrogen peroxide.

  5. Effect of light energy on peroxide tooth bleaching.

    Science.gov (United States)

    Luk, Karen; Tam, Laura; Hubert, Manfred

    2004-02-01

    Light-activated bleaching is a method of tooth whitening. The authors conducted a study to compare the whitening effects and tooth temperature changes induced by various combinations of peroxide bleaches and light sources. The authors randomly assigned 250 extracted human teeth halves into experimental groups (n = 10). A placebo gel (control), a 35 percent hydrogen peroxide or a 10 percent carbamide peroxide bleach was placed on the tooth surface and was irradiated with no light (control); a halogen curing light; an infrared, or IR, light; an argon laser; or a carbon dioxide, or CO2, laser. Color changes were evaluated immediately, one day and one week after treatment using a value-oriented shade guide and an electronic dental color analyzer. The outer enamel and inner dentin surface temperatures were monitored before and immediately after each 30-second application of light using a thermocouple thermometer. Color and temperature changes were significantly affected by an interaction of the bleach and light variables. The application of lights significantly improved the whitening efficacy of some bleach materials, but it caused significant temperature increases in the outer and inner tooth surfaces. The IR and CO2 laser lights caused the highest tooth temperature increases. Dentists performing an in-office bleaching technique with the use of an additional light source to accelerate tooth whitening should consider the specific bleaching agent being used, as well as the potential risks of heating teeth. A specific combination of bleach and light that demonstrates good color change and little temperature rise should be selected for in-office tooth bleaching.

  6. Reuse of discarded deactivated bleaching earth in the bleaching of oils

    Directory of Open Access Journals (Sweden)

    Girgis, Adel Y.

    2005-03-01

    Full Text Available Discarded bleaching earth was used after its reactivation for the bleaching of sunflower, soybean and corn oils. The efficiency of reactivated bleaching earth was compared to the efficiency of virgin activated bleaching earth. Acid reactivated earth (pH 2.5-3 had a slightly higher content in silicone than virgin activated or neutralized reactivated earths. The best results in the color of sunflower and corn oils were obtained when neutralized earth (pH 6–7 was used at 1 and 2 % levels. Acid reactivated earth used at 2 % achieved a higher reduction in soybean oil color than virgin earth (pH 3 at the same dosage. Both reactivated earths reduced peroxide value, iron, conjugated dienes and soap, while they increased acidity and conjugated trienes. Furthermore, these reactivated earths determined higher decrements in the oil induction period than virgin earth. Reactivated earth could be used for 5 cycles for the bleaching of soybean or corn oils and for more than 6 cycles for sunflower oil.Tierra decolorante desechada, fue empleada, tras su reactivación para decolorar aceites de girasol, soja y maíz. La eficiencia de la tierra decolorante reactivada fue comparada con la de la virgen activada. La tierra reactivada ácida (pH 2,5–3 tuvo ligeramente mayor contenido en silicona que la tierra virgen o la reactivada neutra. Los mejores resultados en el color de los aceites de girasol y maíz fueron obtenidos cuando se emplearon niveles del 1 y 2 % de tierra reactivada neutra (pH 6-7. La tierra ácida reactivada, usada al 2 % consiguió una mayor reducción del color del aceite de soja, que una misma dosis de tierra virgen (pH 3. Ambas tierras reactivadas redujeron el índice de peróxidos, hierro, dienos conjugados y jabón de los aceites, mientras que hicieron aumentar la acidez y los trienos conjugados. Además, estas tierras reactivadas determinaron mayores descensos en los periodos de inducción del aceite que la tierra virgen. Las tierras

  7. Bleaching of Wool with Sodium Borohydride

    OpenAIRE

    Duygu Yilmazer, MSc.; Mehmet Kanik, Ph.D.

    2009-01-01

    An untreated wool fabric was bleached both with sodium borohydride (SBH) in the presence of sodium bisulphite (SBS) solution and with a commercial H2O2 bleaching method. The concentration effects of SBH and SBS, bleaching time, pH and temperature on SBH bleaching process were investigated. Whiteness, yellowness and alkali solubility results were assessed for both bleaching methods. The results showed that whiteness degrees obtained with SBH bleaching was comparable with that of H2O2 bleaching...

  8. The effect of two bleaching agents on the phosphate concentration of the enamel evaluated by Raman spectroscopy: An ex vivo study

    Directory of Open Access Journals (Sweden)

    Sokkalingam Mothilal Venkatesan

    2012-01-01

    Full Text Available Aim : The aim of this ex vivo study was to evaluate the effect of in-office bleaching agents,-35% and 38% hydrogen peroxide containing bleaching agents, on the phosphate concentration of the enamel evaluated by Raman spectroscopy. Materials and Methods : Forty noncarious, craze-free human maxillary incisors, extracted for periodontal reasons, were used in this study. Baseline Raman spectra from each specimen were obtained before the application of the bleaching agent to assess the phosphate content present in the teeth. The teeth were divided into two groups: Group A - bleached with pola office bleach (35% hydrogen peroxide, potassium nitrate (light activated. Group B - bleached with opalescence Xtra bleach (38% hydrogen peroxide potassium nitrate and fluoride (chemical activated. After the bleaching procedure, the treated specimens were taken to obtain Raman spectra to assess the phosphate loss after bleaching treatment. Results : The results showed that the chemically activated bleaching agent showed less phosphate loss when compared with the light activated bleaching agent. Conclusion : Within the limitations of this study, it can be concluded that the chemically activated bleaching agent showed minimal phosphate loss when compared to light activated bleaching agent. The chemically activated bleaching agent was better than the light activated bleaching agent when values were evaluated statistically.

  9. Opalescence of bleached teeth.

    Science.gov (United States)

    Schmeling, Max; Maia, Hamilton Pires; Baratieri, Luiz Narciso

    2012-07-01

    To evaluate the influence of tooth bleaching on the opalescence properties of enamel. Color of 38 specimens was determined by colorimetric analysis before and after bleaching in the reflectance and transmittance modes. The results were described as CIELab color coordinates. The Opalescent Parameter (OP) was calculated as the difference in yellow-blue color coordinate (CIE Δb*) and red-green color coordinate (CIE Δa*) between the reflected and transmitted colors. Mean OP value of the specimens was 18.9 (±1.6) before bleaching and 16.1 (±1.0) after bleaching. Bleaching decreases the OP of the specimens (p>0.001). OP decrease was correlated with differences in b* color coordinate in the transmittance mode. Copyright © 2012 Elsevier Ltd. All rights reserved.

  10. In vitro colorimetric evaluation of the efficacy of home bleaching and over-the-counter bleaching products.

    Science.gov (United States)

    Dietschi, Didier; Benbachir, Nacer; Krejci, Ivo

    2010-06-01

    Various bleaching modalities are now offered to patients, either monitored by the dental office or self-directed, for which relative efficiency is unknown. The aim of this in vitro study was to evaluate the ability of bleaching products and protocols to lighten enamel and dentin. Bovine tooth specimens of standardized thickness (2.5 +/- 0.025 mm with similar dentin and enamel thickness) were prepared and stained with whole blood and hemolysate before being submitted to seven supervised or self-directed bleaching regimens: tray-based bleaching using 10% (Opalescence, Ultradent; Nite White, Discus Dental) or light-activated 30% (Metatray, Metatray) carbamide peroxide (CP); 6% (Zoom, Discus Dental) or 9% (TresWhite, Ultradent) hydrogen peroxide (HP); strips (Whitening Strips, Oral B-Rembrandt); and paint-on gel (Paint on Plus, Ivoclar Vivadent) containing 8.1% and 6% HP, respectively. Colorimetric measurements were performed on each specimen side, according to the CIE L*a*b* system, before and after staining, as well as after 5, 10, and the recommended number of bleaching applications. Color change after recommended number of applications (DEr) varied from 15.72 (Metatray) to 29.67 (Nite White) at enamel and 14.91 (Paint on Plus) to 41.43 (Nite White) at dentin side; Nite White (10% CP) and TresWhite (9% HP) were more effective than Metatray (30% CP) and Paint on Plus (6% HP) after 5 or the recommended number of applications. In this in vitro study based on bovine teeth, tray-based systems produced the faster and better bleaching effect, regardless of the product and concentration used, at both enamel and dentin sides.

  11. Peroxy bleaches

    International Nuclear Information System (INIS)

    Carson, P.A.; Fairclough, C.S.; Mauduit, C.; Colsell, M.

    2006-01-01

    The thermodynamic and kinetic properties of a series of inorganic and organic peroxy bleaches were determined using adiabatic rate calorimetry and isothermal microcalorimetry. Results are compared to calculated oxygen balance values. The decomposition of the majority of the compounds is complex. Data indicate the need for cooling during the storage and transport for some materials evaluated. Although no overall structure/activity relationship could be established because of the diversity of molecular architectures studied, a combination of decomposition and activation energy data provides a means for hazard and risk classification

  12. Short communication: The influence of solids concentration and bleaching agent on bleaching efficacy and flavor of sweet whey powder.

    Science.gov (United States)

    Jervis, M G; Smith, T J; Drake, M A

    2015-04-01

    Recent studies have demonstrated the effect of bleaching conditions and bleaching agent on flavor and functional properties of whey protein ingredients. Solids concentration at bleaching significantly affected bleaching efficacy and flavor effects of different bleaching agents. It is not known if these parameters influence quality of sweet whey powder (SWP). The purpose of this study was to determine the effects of solids concentration and bleaching agent on the flavor and bleaching efficacy of SWP. Colored cheddar whey was manufactured, fat separated, and pasteurized. Subsequently, the whey (6.7% solids) was bleached, concentrated using reverse osmosis (RO) to 14% solids, and then spray dried, or whey was concentrated before bleaching and then spray dried. Bleaching treatments included a control (no bleaching, 50 °C, 60 min), hydrogen peroxide (HP; 250 mg/kg, 50 °C, 60 min), benzoyl peroxide (50 mg/kg, 50 °C, 60 min), lactoperoxidase (20 mg/kg of HP, 50 °C, 30 min), and external peroxidase (MaxiBright, DSM Food Specialties, Delft, the Netherlands; 2 dairy bleaching units/mL, 50 °C, 30 min). The experiment was repeated in triplicate. Sensory properties and volatile compounds of SWP were evaluated by a trained panel and gas chromatography-mass spectrometry, respectively. Bleaching efficacy (norbixin destruction) and benzoic acid were measured by HPLC. Differences in bleaching efficacy, sensory and volatile compound profiles, and benzoic acid were observed with different bleaching agents, consistent with previous studies. Solids concentration affected bleaching efficacy of HP, but not other bleaching agents. The SWP from whey bleached with HP or lactoperoxidase following RO had increased cardboard and fatty flavors and higher concentrations of lipid oxidation compounds compared with SWP from whey bleached before RO. The SWP bleached with benzoyl peroxide after RO contained less benzoic acid than SWP from whey bleached before RO. These results indicate that

  13. Body image disturbance and skin bleaching.

    Science.gov (United States)

    Charles, Christopher A D; McLean, Shua-Kym

    2017-11-01

    This study looks at body image disturbance among Jamaicans who bleach their skin. The hypothesis states that there is a positive relationship between skin bleaching and body image disturbance. The study used a convenience sample of 160 participants with a skin bleaching group (n = 80) and a non-bleaching comparison group (n = 80). The instrument included demographic questions, the body image disturbance questionnaire (BIDQ), and questions about skin bleaching. The results of a t-test revealed that the skin bleaching group (M = 1.5255, SD = 0.42169) was not significantly different from the non-bleaching group (M = 1.4938, SD = 0.74217) in terms of body image disturbance, t(158) = 0.333, p = .740. The participants who bleached did not suffer from body image disturbance. Self-reports revealed that they bleached to acquire beauty, attract a partner, elude the police, and market skin bleaching products. The practice was fashionable and popular and it made some participants feel good, while others were fans of a popular musical artiste who bleached his skin. The majority of participants bleached because of the perceived personal, social, and entrepreneurial benefits of the practice and not because they suffered emotional distress, anxiety, and functional impairment because of their skin colour. However, there was some level of BID among the minority of participants who argued that they bleached because they wanted to be pretty so they were emotionally distressed about there body image and experienced functional impairment. © 2017 The British Psychological Society.

  14. Bleaching and enamel surface interactions resulting from the use of highly-concentrated bleaching gels.

    Science.gov (United States)

    Grazioli, Guillermo; Valente, Lisia Lorea; Isolan, Cristina Pereira; Pinheiro, Helena Alves; Duarte, Camila Gonçalves; Münchow, Eliseu Aldrighi

    2018-03-01

    Tooth bleaching is considered a non-invasive treatment, although the use of highly-concentrated products may provoke increased surface roughness and enamel demineralization, as well as postoperative sensitivity. Thus, the aim of this study was to investigate whether hydrogen peroxide (H 2 O 2 ) concentration would affect tooth bleaching effectiveness and the enamel surface properties. Enamel/dentin bovine specimens (6 × 4 mm) were immersed in coffee solution for 7 days and evaluated with a spectrophotometer (Easyshade; baseline), using the CIEL * a * b * color parameters. Hardness was measured using a hardness tester. The specimens were randomly assigned into four groups: one negative control, in which the specimens were not bleached, but they were irradiated with a laser-light source (Whitening Lase II, DMC Equipments); and three groups using distinct H 2 O 2 concentration, namely LP15% (15% Lase Peroxide Lite), LP25% (25% Lase Peroxide Sensy), and LP35% (35% Lase Peroxide Sensy), all products from DMC. The bleached specimens were also irradiated with the laser-light source. After bleaching, all specimens were evaluated using scanning electron microscopy (SEM). pH kinetics and rate was monitored during bleaching. The data were analyzed using ANOVA and Tukey's test (p bleaching gels produced similar color change (p > 0.05). Concerning hardness, only the LP25% and LP35% significantly reduced hardness after bleaching; also, there was a progressive tendency for a greater percentage reduction in hardness with increased H 2 O 2 concentration of the gel (R 2  = 0.9973, p bleaching effectiveness, and may increase the possibility for alteration of enamel hardness, surface morphology, and acidity of the medium. When using H 2 O 2 -based bleaching agents, dental practitioners should choose for less concentrated gels, e.g., around the 15% level. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Changes in bleaching susceptibility among corals subject to ocean warming and recurrent bleaching in Moorea, French Polynesia.

    Science.gov (United States)

    Pratchett, Morgan S; McCowan, Dominique; Maynard, Jeffrey A; Heron, Scott F

    2013-01-01

    Climate-induced coral bleaching poses a major threat to coral reef ecosystems, mostly because of the sensitivities of key habitat-forming corals to increasing temperature. However, susceptibility to bleaching varies greatly among coral genera and there are likely to be major changes in the relative abundance of different corals, even if the wholesale loss of corals does not occur for several decades. Here we document variation in bleaching susceptibility among key genera of reef-building corals in Moorea, French Polynesia, and compare bleaching incidence during mass-bleaching events documented in 1991, 1994, 2002 and 2007. This study compared the proportion of colonies that bleached for four major genera of reef-building corals (Acropora, Montipora, Pocillopora and Porites), during each of four well-documented bleaching events from 1991 to 2007. Acropora and Montipora consistently bleached in far greater proportions (up to 98%) than Pocillopora and Porites. However, there was an apparent and sustained decline in the proportion of colonies that bleached during successive bleaching events, especially for Acropora and Montipora. In 2007, only 77% of Acropora colonies bleached compared with 98% in 1991. Temporal variation in the proportion of coral colonies bleached may be attributable to differences in environmental conditions among years. Alternately, the sustained declines in bleaching incidence among highly susceptible corals may be indicative of acclimation or adaptation. Coral genera that are highly susceptible to coral bleaching, and especially Acropora and Montipora, exhibit temporal declines in their susceptibility to thermal anomalies at Moorea, French Polynesia. One possible explanation for these findings is that gradual removal of highly susceptible genotypes (through selective mortality of individuals, populations, and/or species) is producing a coral assemblage that is more resistant to sustained and ongoing ocean warming.

  16. Changes in Bleaching Susceptibility among Corals Subject to Ocean Warming and Recurrent Bleaching in Moorea, French Polynesia

    Science.gov (United States)

    Pratchett, Morgan S.; McCowan, Dominique; Maynard, Jeffrey A.; Heron, Scott F.

    2013-01-01

    Background Climate-induced coral bleaching poses a major threat to coral reef ecosystems, mostly because of the sensitivities of key habitat-forming corals to increasing temperature. However, susceptibility to bleaching varies greatly among coral genera and there are likely to be major changes in the relative abundance of different corals, even if the wholesale loss of corals does not occur for several decades. Here we document variation in bleaching susceptibility among key genera of reef-building corals in Moorea, French Polynesia, and compare bleaching incidence during mass-bleaching events documented in 1991, 1994, 2002 and 2007. Methodology/Principal Findings This study compared the proportion of colonies that bleached for four major genera of reef-building corals (Acropora, Montipora, Pocillopora and Porites), during each of four well-documented bleaching events from 1991 to 2007. Acropora and Montipora consistently bleached in far greater proportions (up to 98%) than Pocillopora and Porites. However, there was an apparent and sustained decline in the proportion of colonies that bleached during successive bleaching events, especially for Acropora and Montipora. In 2007, only 77% of Acropora colonies bleached compared with 98% in 1991. Temporal variation in the proportion of coral colonies bleached may be attributable to differences in environmental conditions among years. Alternately, the sustained declines in bleaching incidence among highly susceptible corals may be indicative of acclimation or adaptation. Conclusions/Significance Coral genera that are highly susceptible to coral bleaching, and especially Acropora and Montipora, exhibit temporal declines in their susceptibility to thermal anomalies at Moorea, French Polynesia. One possible explanation for these findings is that gradual removal of highly susceptible genotypes (through selective mortality of individuals, populations, and/or species) is producing a coral assemblage that is more resistant to

  17. Thermal and optical bleaching of radiation effects in silver activated metaphosphate glass - its use in U.V. dosimetry

    International Nuclear Information System (INIS)

    Nagpal, J.S.; Ramanathan, G.; Gangadharan, P.

    1976-01-01

    While investigating the use of silver activated metaphosphate glass in radiation dosimetry, using its properties of radiophotoluminescence (RPL) in the range 20 mR to 10 3 R and of optical absorbance changes at higher exposures, a difference in the behaviour of the centers responsible for the two phenomenon was observed when the glass was exposed to 253.7 nm u.v. Ultraviolet exposure was observed to bleach the radiophotoluminescence in an irradiated glass whereas it was observed to induce photoluminescence in an unirradiated glass. Thermal behaviour of the two centers was also different. After heating the glass for 5 min at a number of temperatures, a gradual increase in RPL was observed up to 200 0 C. Above 200 0 C, the thermal treatment bleached the RPL. The optical absorbance was bleached from room temperature upwards. (U.K.)

  18. IDENTIFIKASI DAN UJI POTENSI BAKTERI LIPOLITIK DARI LIMBAH SBE (SPENT BLEACHING EARTH SEBAGAI AGEN BIOREMEDIASI

    Directory of Open Access Journals (Sweden)

    Fitralia Elyza

    2016-03-01

    Full Text Available Limbah minyak kelapa sawit yang terbanyak adalah SBE (Spent Bleaching Earth, limbah ini mengandung residu minyak tinggi yang dapat mencemari lingkungan, 30% residu minyak pada limbah SBE dapat digunakan bakteri untuk pertumbuhannya, sehingga adanya bakteri mampu menjadi agen bioremediasi pencemaran SBE. Penelitian dilakukan untuk mendapatkan bakteri lipolitik sebagai agen potensial bioremediasi pada limbah SBE. Metode pengambilan sampel limbah SBE secara random sampling. Sampel tanah diambil secara acak dari beberapa titik area limbah SBE. Bakteri diisolasi dari sampel limbah SBE, kemudian dilakukan tahapan yaitu : pemurnian, seleksi, uji potensi, bakteri berpotensi mereduksi lipid dikarakterisasi dan diidentifikasi genusnya. Hasil penelitian menunjukkan bahwa Aktivitas enzim lipase yang tinggi menandakan bahwa bakteri lipolitik bekerja optimal merombak zat pencemar. Bakteri yang memiliki potensi sebagai agen bioremediasi terdiri dari genus Citrobacter (B1, Enterobacter (B2 dan Acinetobacter (B3. The most palm oil waste is SBE (Spent Bleaching Earth, this waste had many reduced lipid that got pollution for inviroments, Bacteria can use lipid from SBE as much as 30% for growed. So that consist of bacteria in SBE as a potensial agent for remediation. This study aims to obtain lipolytic bacteria as a potential agent of bioremediation. The method of sampling soil were taken at random from SBE waste, Bacteria were isolated from the SBE waste, then they were selected into steps : performed purification, selection, potential test, then characterized and identified it’s genus of potential bacteria. The results showed that the higest activity enzyme of lipolytic indicated that the lipolytic bacteria worked optimal for reduce polution. Bacteria had potential as a bioremediation agent consisting of genus Citrobacter (B1, Enterobacter (B2 and Acinetobacter (B3.

  19. Differential coral bleaching-Contrasting the activity and response of enzymatic antioxidants in symbiotic partners under thermal stress.

    Science.gov (United States)

    Krueger, Thomas; Hawkins, Thomas D; Becker, Susanne; Pontasch, Stefanie; Dove, Sophie; Hoegh-Guldberg, Ove; Leggat, William; Fisher, Paul L; Davy, Simon K

    2015-12-01

    Mass coral bleaching due to thermal stress represents a major threat to the integrity and functioning of coral reefs. Thermal thresholds vary, however, between corals, partly as a result of the specific type of endosymbiotic dinoflagellate (Symbiodinium sp.) they harbour. The production of reactive oxygen species (ROS) in corals under thermal and light stress has been recognised as one mechanism that can lead to cellular damage and the loss of their symbiont population (Oxidative Theory of Coral Bleaching). Here, we compared the response of symbiont and host enzymatic antioxidants in the coral species Acropora millepora and Montipora digitata at 28°C and 33°C. A. millepora at 33°C showed a decrease in photochemical efficiency of photosystem II (PSII) and increase in maximum midday excitation pressure on PSII, with subsequent bleaching (declining photosynthetic pigment and symbiont density). M. digitata exhibited no bleaching response and photochemical changes in its symbionts were minor. The symbiont antioxidant enzymes superoxide dismutase, ascorbate peroxidase, and catalase peroxidase showed no significant upregulation to elevated temperatures in either coral, while only catalase was significantly elevated in both coral hosts at 33°C. Increased host catalase activity in the susceptible coral after 5days at 33°C was independent of antioxidant responses in the symbiont and preceded significant declines in PSII photochemical efficiencies. This finding suggests a potential decoupling of host redox mechanisms from symbiont photophysiology and raises questions about the importance of symbiont-derived ROS in initiating coral bleaching. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Bleaching Dengan Teknologi Laser

    OpenAIRE

    Eliwaty

    2008-01-01

    Penulisan tentang bleaching dengan laser dimaksudkan untuk menambah wawasan serta pengetahuan dari pembaca di bidang kedokteran gigi. Macam-macam laser yang dipergunakan dalam bleaching yaitu argon, CO2 serta dioda laser. Contoh merek produk laser yaitu Blulaze, Dentcure untuk argonlaser, Novapulse untuk C02 serta Opus 5 untuk dioda laser. Laser bleaching hasilnya dapat dicapai dalam satu kunjungan saja, cepat, efisien namun biayanya relatif mahal, dapat menimbulkan burn, sensitivitas se...

  1. Anemone bleaching increases the metabolic demands of symbiont anemonefish.

    Science.gov (United States)

    Norin, Tommy; Mills, Suzanne C; Crespel, Amélie; Cortese, Daphne; Killen, Shaun S; Beldade, Ricardo

    2018-04-11

    Increased ocean temperatures are causing mass bleaching of anemones and corals in the tropics worldwide. While such heat-induced loss of algal symbionts (zooxanthellae) directly affects anemones and corals physiologically, this damage may also cascade on to other animal symbionts. Metabolic rate is an integrative physiological trait shown to relate to various aspects of organismal performance, behaviour and locomotor capacity, and also shows plasticity during exposure to acute and chronic stressors. As climate warming is expected to affect the physiology, behaviour and life history of animals, including ectotherms such as fish, we measured if residing in bleached versus unbleached sea anemones ( Heteractis magnifica ) affected the standard (i.e. baseline) metabolic rate and behaviour (activity) of juvenile orange-fin anemonefish ( Amphiprion chrysopterus ) . Metabolic rate was estimated from rates of oxygen uptake [Formula: see text], and the standard metabolic rate [Formula: see text] of anemonefish from bleached anemones was significantly higher by 8.2% compared with that of fish residing in unbleached anemones, possibly due to increased stress levels. Activity levels did not differ between fish from bleached and unbleached anemones. As [Formula: see text] reflects the minimum cost of living, the increased metabolic demands may contribute to the negative impacts of bleaching on important anemonefish life history and fitness traits observed previously (e.g. reduced spawning frequency and lower fecundity). © 2018 The Author(s).

  2. Exogenous bleaching evaluation on dentin using chemical activated technique compared with diode laser technique

    International Nuclear Information System (INIS)

    Carvalho, Breno Carnevalli Franco de

    2003-01-01

    This in vitro study compared the results of different exogenous bleaching proceedings on dentin after treatment of enamel surface. Thirty human canine were hewn preserving the vestibular half of the crown and 3 mm of root, showing a vestibular-lingual thickness average of 3,5 mm, measuring in the third middle of the crown. Ali teeth were maintained in wet chamber during the experiment. Digital photographs were taken of the dentin surface at 3 experimental times (LI: initial record, L0: immediate pos-bleaching record and L 15: 15 days after bleaching). The teeth were divided into 3 experimental groups of 10 teeth in each. The Control Group did not receive any kind of treatment. The Laser Group received 2 session of laser bleaching, with 3 applications each, using 35% hydrogen peroxide, activated by diode laser during 30 seconds, by scanning the enamel surface from incisal edge to the top of the crown, from mesial to distal portion of the crown and circularly, each movement during 10 seconds. The following parameters being adopted: wavelength of 808 nm, power of 1,5 W and optic fiber with 600 μm (core). The Peroxide Group received 28 daily applications, during 4 hours each application, using 16% carbamide peroxide. The bleaching records were analysed using a computer, through RGBK (red, green , blue and black). The K averages (K=100% for black and K=0% for white) of the records for Control Group were: LI=50,1 %, L0=50,3% and L 15=50,6%. For Laser Group the K averages were LI=48,5%, L0=50,0% and L 15=47,7%. And for the Peroxide Group were LI=50,5%, L0=35,9% and L 15=37,3%. The statistical analysis showed no significant difference of the K between the Control Group and the Laser Group, as to LI, L0 and L 15. Only Peroxide Group showed significant statistical difference between LI with L0 and L 15 (0,1%), and L0 in comparison with L 15 did not show any difference. (author)

  3. An innovative chairside bleaching protocol for treating stained dentition: initial results.

    Science.gov (United States)

    Miara, P

    2000-09-01

    For years, investigators have attempted to develop a predictable means of bleaching pathologically and nonpathologically stained dentition. While previous efforts have modified the concentration of the bleaching material, the duration of the procedure, and the manner by which the bleaching agent is activated, the ability to affect a significant shade improvement remains an elusive objective. This article demonstrates an innovative technique used to influence the penetration of oxygen ions into the tooth enamel, which may resolve this clinical dilemma.

  4. Assessment of bleaching of K-feldspar grains

    International Nuclear Information System (INIS)

    Zhang Jiafu; Li Shenghua; Tso, M-Y.W.

    2001-01-01

    Based on the difference in the bleaching rate between IRSL and TL signals, a new method of assessing the bleaching of sedimentary feldspar is proposed. All measurements for De and the bleaching factor (normalized ratio of IRSL to TL) are carried out on the same grain. K-feldspar grains from two sediments, a marine and an alluvium, from Hong Kong were tested. Their bleaching factors indicate that bleaching of the marine sediment was not uniform, whereas the latter was relatively homogeneous. Furthermore, the relatively well-bleached grains in each sample were identified

  5. Influence of dental bleaching on marginal leakage of Class V restorations

    Directory of Open Access Journals (Sweden)

    Andréia Cristina Ramos Dorini

    2010-04-01

    Full Text Available Objective: Evaluate the in vitro effect of bleaching performed in the dental office and waiting time on the degree of microleakage in class V cavities with margins in enamel, restored with resin composite. Methods: Forty-five human third molars were used, in which the vestibular faces were bleached with 35% hydrogen peroxide activated with LED and the palatine faces were not bleached (control. The teeth were randomly divided into 3 groups with 15 teeth in each: Group 1, restored immediately after bleaching; Group 2, seven days after bleaching; and Group 3, fourteen days after bleaching. After cavity preparation, 35% phosphoric acid, Adper Single Bond 2 adhesive (3M ESPE, St. Paul, Mn, USA, and resin composite Filtek Z250 (3M ESPE, St. Paul, MN, USA were applied. The teeth were thermal cycled and sealed with red nail polish on the bleached faces and blue on the non bleached faces, except for 1mm around the restored region. The samples were classified according to the following scores: 0 = no leakage, 1 = minimum leakage (less than 1 / 3 the length of the wall, 2 = moderate leakage (1/3 to 2/3 of the wall and 3 = extensive leakage (over 2/3 of the wall. The data were submitted to the Kruskal-Wallis test at a level of significance of 5%. Results: The restorative procedure immediately after bleaching resulted in statistically higher microleakage values (p 0.05. Conclusion: Based on the results, it is advisable to wait at least 7 days after bleaching to make the definitive restoration.

  6. Atmospheric Pressure Plasma Jet as an Accelerator of Tooth Bleaching

    Directory of Open Access Journals (Sweden)

    Vedran Šantak

    2014-01-01

    Full Text Available Objective: To study the effect of atmospheric pressure plasma (APP jet as a potential accelerator of the degradation of hydrogen peroxide in bleaching gels which could lead to better and faster bleaching. Material and Methods: 25 pastilles of hydroxylapatite were colored in green tea for 8 hours and were randomly divided into five groups (n = 5. The bleaching process was performed with 30% and 40% hydrogen peroxide (HP gel alone and in conjunction with helium APP jet. During the bleaching treatment, optical emission spectroscopy and non-contact surface temperature measurement using pyrometer were performed. Color of the pastilles was determined by a red– green–blue (RGB colorimeter. PH values of bleaching gels were measured before and after the plasma treatment on additional 10 pastilles using a pH meter with contact pH electrode. Results: The color measurements of pastilles before and after the treatment showed that treatment with APP jet improved the bleaching effect by 32% and 15% in the case of 30 % and 40% HP gel. Better results were obtained approximately six times faster than with a procedure suggested by the bleaching gel manufacturer. Optical emission spectroscopy proved that plasma has a chemically active role on the gel. After the APP treatment, pH values of bleaching gels dropped to about 50–75% of their initial value while the surface temperature increased by 8–10˚C above baseline. Conclusion: The use of plasma jet provides more effective bleaching results in a shorter period of time without a significant temperature increase which may cause damage of the surrounding tissue.

  7. The effects of coral bleaching on settlement preferences and growth of juvenile butterflyfishes.

    Science.gov (United States)

    Cole, A J; Lawton, R J; Pisapia, C; Pratchett, M S

    2014-07-01

    Coral bleaching and associated mortality is an increasingly prominent threat to coral reef ecosystems. Although the effects of bleaching-induced coral mortality on reef fishes have been well demonstrated, corals can remain bleached for several weeks prior to recovery or death and little is known about how bleaching affects resident fishes during this time period. This study compared growth rates of two species of juvenile butterflyfishes (Chaetodon aureofasciatus and Chaetodon lunulatus) that were restricted to feeding upon either bleached or healthy coral tissue of Acropora spathulata or Pocillopora damicornis. Coral condition (bleached vs. unbleached) had no significant effects on changes in total length or weight over a 23-day period. Likewise, in a habitat choice experiment, juvenile butterflyfishes did not discriminate between healthy and bleached corals, but actively avoided using recently dead colonies. These results indicate that juvenile coral-feeding fishes are relatively robust to short term effects of bleaching events, provided that the corals do recover. Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.

  8. Perbandingan intensitas warna CPO dengan menggunakan Bleaching Earth (BE) dan Spent Bleaching Earth (SBE) di PT. SMART Tbk.

    OpenAIRE

    Aritonang, Dwi Christina

    2016-01-01

    Comparative studies have been conducted on the effect of bleaching earth quality bleachibility power on CPO (crude palm oil). by using the tool Lovibond Tintometer model of F in PT Smart Tbk Medan – Belawan.From experiments obtained initial color with the CPO 20R - 20Y after addition Bleaching Earth and spent bleaching earth with the CPO each - each 10,2R - 20Y and 17.3R - 20Y . The results showed that purification using Bleaching Earth better than the purification of Spent Bleaching Earh ...

  9. Removal of Methylene Blue from aqueous solution using spent bleaching earth

    Science.gov (United States)

    Saputra, E.; Saputra, R.; Nugraha, M. W.; Irianty, R. S.; Utama, P. S.

    2018-04-01

    The waste from industrial textile waste is one of the environmental problems, it is required effective and efficient processing. In this study spent bleaching earth was used as absorbent. It was found that the absorbent was effective to remove methylene blue from aqueous solution with removal efficiency 99.97 % in 120 min. Several parameters such as pH, amount of absorbent loading, stirring speed are found as key factor influencing removal of methylene blue. The mechanism of adsorption was also studied, and it was found that Langmuir isotherm fitted to data of experiment with adsorption capacity 0.5 mg/g.

  10. Coral reef bleaching: ecological perspectives

    Science.gov (United States)

    Glynn, P. W.

    1993-03-01

    Coral reef bleaching, the whitening of diverse invertebrate taxa, results from the loss of symbiotic zooxanthellae and/or a reduction in photosynthetic pigment concentrations in zooxanthellae residing within the gastrodermal tissues of host animals. Of particular concern are the consequences of bleaching of large numbers of reef-building scleractinian corals and hydrocorals. Published records of coral reef bleaching events from 1870 to the present suggest that the frequency (60 major events from 1979 to 1990), scale (co-occurrence in many coral reef regions and often over the bathymetric depth range of corals) and severity (>95% mortality in some areas) of recent bleaching disturbances are unprecedented in the scientific literature. The causes of small scale, isolated bleaching events can often be explained by particular stressors (e.g., temperature, salinity, light, sedimentation, aerial exposure and pollutants), but attempts to explain large scale bleaching events in terms of possible global change (e.g., greenhouse warming, increased UV radiation flux, deteriorating ecosystem health, or some combination of the above) have not been convincing. Attempts to relate the severity and extent of large scale coral reef bleaching events to particular causes have been hampered by a lack of (a) standardized methods to assess bleaching and (b) continuous, long-term data bases of environmental conditions over the periods of interest. An effort must be made to understand the impact of bleaching on the remainder of the reef community and the long-term effects on competition, predation, symbioses, bioerosion and substrate condition, all factors that can influence coral recruitment and reef recovery. If projected rates of sea warming are realized by mid to late AD 2000, i.e. a 2°C increase in high latitude coral seas, the upper thermal tolerance limits of many reef-building corals could be exceeded. Present evidence suggests that many corals would be unable to adapt

  11. BLEACHING NEPTUNE BALLS

    Directory of Open Access Journals (Sweden)

    BONET Maria Angeles

    2014-05-01

    Full Text Available Posidonia Oceanic is a seaweed from Mediterranean Sea and it is more concentrated at the Balerian SEA. This implies the Valencian Community also. It forms vaste underwater meadows in the sea and are part of the Mediterranean ecosystem. It is a sea-grass specie with fruits and flowers. Leaves are ribbon-like and they grow in winter and at the end of summer some of them are separated and arrive to some sea line. Fuit is separated and can floate, it is known as “the olive of the sea” mainly in Italy, or as the Neptune Balls. As it can be used in different fields, it is is being studied in order ro have the precitice tests. Some authors have reported the manufacturing of fully bio-based comites with a gluten matrix by hot-press molding. And it has been considered as an effective insulator for building industry or even though to determine the presence of mercure in the Mediterranean sea some years ago. As many applications can be designed from that fibers, it has been considered to be bleached in order to used them in fashionable products. Consequently, its original brown color is not the most suitable one and it should be bleached as many other cellulosic fibers. The aim of this paper is to bleache neptune balls however, the inner fibers were not accessible at all and it implied not to bleach the inner fibers in the neptune ball. Further studiesd will consider bleaching the individualized fibers.

  12. Arundo donax L. reed: new perspectives for pulping and bleaching. Part 4. Peroxide bleaching of organosolv pulps.

    Science.gov (United States)

    Shatalov, A A; Pereira, H

    2005-05-01

    A comparative study on TCF (totally chlorine-free) bleachability of organosolv pulps from the annual fibre crop Arundo donax L. (giant reed) was carried out using a simple three-stage peroxide bleaching sequence without oxygen pre-bleaching. ASAM (alkali-sulfite-anthraquinone-methanol), Organocell (alkali-anthraquinone-methanol) and ethanol-soda organosolv pulps were bleached and compared with kraft pulp, as a reference. The final brightness of 76-78% ISO was attained for all tested pulps. The chemical charge required to reach this level of brightness varied for different pulps (despite the equal initial content of the residual lignin) and directly related to starting brightness values. No direct correlation between brightness improvement and lignin removal during bleaching was found, indicating the influence of the specific pulp properties introduced by pulping process on bleaching chemistry. The general higher bleaching response of organosolv pulps from A. donax was noted in comparison with kraft.

  13. Color recovery effect of different bleaching systems on a discolored composite resin.

    Science.gov (United States)

    Gul, P; Harorlı, O T; Ocal, I B; Ergin, Z; Barutcigil, C

    2017-10-01

    Discoloration of resin-based composites is a commonly encountered problem, and bleaching agents may be used for the therapy of the existing discoloration. The purpose of this study was to investigate in vitro color recovery effect of different bleaching systems on the heavily discolored composite resin. Fifty disk-shaped dental composite specimens were prepared using A2 shade nanohybrid universal composite resin (3M ESPE Filtek Z550, St. Paul, MN, USA). Composite samples were immersed in coffee and turnip juice for 1 week in each. One laser activated bleaching (LB) (Biolase Laserwhite*20) and three conventional bleaching systems (Ultradent Opalescence Boost 40% (OB), Ultradent Opalescence PF 15% home bleaching (HB), Crest 3D White [Whitening Mouthwash]) were tested in this study. Distilled water was used as control group. The color of the samples were measured using a spectrophotometer (VITA Easy shade Compact, VITA Zahnfabrik, Bad Säckingen, Germany). Color changes (ΔE00) were calculated using the CIEDE2000 formula. Statistical analyses were conducted using paired samples test, one-way analysis of variance, and Tukey's multiple comparison tests (α = 0.05). The staining beverages caused perceptible discoloration (ΔE00 > 2.25). The color recovery effect of all bleaching systems was statistically determined to be more effective than the control group (P OB group was found as the most effective bleaching system, there was no statistically significant difference among HB, OB, and LB groups (P > 0.05). Within the limitation of this in vitro study, the highest recovery effect was determined in office bleaching system among all bleaching systems. However, home and laser bleaching systems were determined as effective as office bleaching system.

  14. The efficacy of laser-assisted in-office bleaching and home bleaching on sound and demineralized enamel

    Science.gov (United States)

    Akbari, Majid; Mohammadpour, Sakineh

    2015-01-01

    Aims: This study investigated the effectiveness of laser-assisted in-office bleaching and home-bleaching in sound and demineralized enamel. Materials and Methods: The sample consisted of 120 freshly-extracted bovine incisors. Half of the specimens were stored in a demineralizing solution to induce white spot lesions. Following exposure to a tea solution for 7.5 days, the specimens were randomly assigned to 4 groups of 30 according to the type of enamel and the bleaching procedure employed. Groups 1 and 2 consisted of demineralized teeth subjected to in-office bleaching and home bleaching, whereas in groups 3 and 4, sound teeth were subjected to in-office and home bleaching, respectively. A diode laser (810 nm, 2 W, continuous wave, four times for 15 seconds each) was employed for assisting the in-office process. The color of the specimens was measured before (T1) and after (T2) staining and during (T3) and after (T4) the bleaching procedures using a spectrophotometer. The color change (ΔE) between different treatments stages was compared among the groups. Results: There were significant differences in the color change between T2 and T3 (ΔE T2–T3) and T2 and T4 (ΔE T2–T4) stages among the study groups (pbleaching (group 1) as compared to the other groups (Pbleaching could provide faster and greater whitening effect than home bleaching on stained demineralized enamel, but both procedures produced comparable results on sound teeth. PMID:26877590

  15. Tropical cyclone cooling combats region-wide coral bleaching.

    Science.gov (United States)

    Carrigan, Adam D; Puotinen, Marji

    2014-05-01

    Coral bleaching has become more frequent and widespread as a result of rising sea surface temperature (SST). During a regional scale SST anomaly, reef exposure to thermal stress is patchy in part due to physical factors that reduce SST to provide thermal refuge. Tropical cyclones (TCs - hurricanes, typhoons) can induce temperature drops at spatial scales comparable to that of the SST anomaly itself. Such cyclone cooling can mitigate bleaching across broad areas when well-timed and appropriately located, yet the spatial and temporal prevalence of this phenomenon has not been quantified. Here, satellite SST and historical TC data are used to reconstruct cool wakes (n=46) across the Caribbean during two active TC seasons (2005 and 2010) where high thermal stress was widespread. Upon comparison of these datasets with thermal stress data from Coral Reef Watch and published accounts of bleaching, it is evident that TC cooling reduced thermal stress at a region-wide scale. The results show that during a mass bleaching event, TC cooling reduced thermal stress below critical levels to potentially mitigate bleaching at some reefs, and interrupted natural warming cycles to slow the build-up of thermal stress at others. Furthermore, reconstructed TC wave damage zones suggest that it was rare for more reef area to be damaged by waves than was cooled (only 12% of TCs). Extending the time series back to 1985 (n = 314), we estimate that for the recent period of enhanced TC activity (1995-2010), the annual probability that cooling and thermal stress co-occur is as high as 31% at some reefs. Quantifying such probabilities across the other tropical regions where both coral reefs and TCs exist is vital for improving our understanding of how reef exposure to rising SSTs may vary, and contributes to a basis for targeting reef conservation. © 2014 John Wiley & Sons Ltd.

  16. Response surface modeling of acid activation of raw diatomite using in sunflower oil bleaching by: Box-Behnken experimental design.

    Science.gov (United States)

    Larouci, M; Safa, M; Meddah, B; Aoues, A; Sonnet, P

    2015-03-01

    The optimum conditions for acid activation of diatomite for maximizing bleaching efficiency of the diatomite in sun flower oil treatment were studied. Box-Behnken experimental design combining with response surface modeling (RSM) and quadratic programming (QP) was employed to obtain the optimum conditions of three independent variables (acid concentration, activation time and solid to liquid) for acid activation of diatomite. The significance of independent variables and their interactions were tested by means of the analysis of variance (ANOVA) with 95 % confidence limits (α = 0.05). The optimum values of the selected variables were obtained by solving the quadratic regression model, as well as by analyzing the response surface contour plots. The experimental conditions at this global point were determined to be acid concentration = 8.963 N, activation time = 11.9878 h, and solid to liquid ratio = 221.2113 g/l, the corresponding bleaching efficiency was found to be about 99 %.

  17. Dental bleaching on teeth submitted to enamel microabrasion 30 years ago-a case report of patients' compliance during bleaching treatment.

    Science.gov (United States)

    Sundfeld, Daniel; Pavani, Caio Cesar; Schott, Timm Cornelius; Machado, Lucas Silveira; Pini, Núbia Inocêncya Pavesi; Bertoz, André Pinheiro de Magalhães; Sundfeld, Renato Herman

    2018-04-20

    The present dental bleaching case report describes a new method that precisely quantifies the daily wearing-times of the bleaching product by inserting a microsensor in the acetate custom tray. The bleaching efficacy was also discussed since the patient was previously submitted to enamel microabrasion. The patient was submitted to enamel microabrasion in 1987, and bleaching treatment was performed in 2005. In 2017, re-bleaching was executed using 10% peroxide carbamide. The electronic microsensor, TheraMon (TheraMon® microelectronic system; Sales Agency Gschladt, Hargelsberg, Austria), was embedded in the labial region of the upper and lower acetate trays to evaluate the wearing-times of the acetate trays/bleaching product. The patient was instructed to wear the tray for 6 to 8 h/day while sleeping. After 24 days of bleaching treatment, the data obtained from the TheraMon electronic devices was collected and interpreted. The patient did not entirely follow the bleaching treatment as recommended, as there was no evidence of use of the upper and lower trays for some days; additionally, the bleaching product was used for shorter and longer periods than was instructed. The TheraMon microeletronic device precisely measured the wearing-times of the acetate tray/bleaching product during the bleaching treatment. Teeth submitted to enamel microabrasion presented with a healthy clinical appearance after 30 years. Measuring the length and frequency of use of an acetate tray/bleaching product can be important to clinicians and patients for obtaining a controlled and adequate bleaching treatment.

  18. Evaluation of the bleached human enamel by Scanning Electron Microscopy

    DEFF Research Database (Denmark)

    Miranda, Carolina Baptista; Pagani, Clovis; Benetti, Ana Raquel

    2005-01-01

    Since bleaching has become a popular procedure, the effect of peroxides on dental hard tissues is of great interest in research. Purpose: The aim of this in vitro study was to perform a qualitative analysis of the human enamel after the application of in-office bleaching agents, using Scanning......: 2h); G3- four 2-hour exposures to 35% carbamide peroxide (total exposure: 8h); G4- two applications of 35% hydrogen peroxide, which was light-activated with halogen lamp at 700mW/cm² during 7min and remained in contact with enamel for 20min (total exposure: 40min). All bleaching treatments adopted...... analysis performing gold sputter coating under vacuum and were examined using 15kV at 500x and 2000x magnification. Results: Morphological alterations on the enamel surface were similarly detected after bleaching with either 35% carbamide peroxide or 35% hydrogen peroxide. Surface porosities were...

  19. Side effects of external tooth bleaching

    DEFF Research Database (Denmark)

    Bruzell, E.M.; Pallesen, Ulla; Thoresen, N.R.

    2013-01-01

    Objective The study was performed to assess the risk of at-home and in-office bleaching procedures, and to recognise potential predictors for side effects. Design Multi-centre, questionnaire-based prospective study with follow-ups at around 14 days and around one year post-treatment. Setting...... General practices and university clinics during the years 2007‑2009 in Scandinavia. Subjects Patients with tooth bleaching as part of the treatment plan. Results The prevalence of experienced tooth sensitivity at first follow-up was independent of bleaching procedure (at-home = 50.3% [n = 143]; in...... attributed to the bleaching treatment in the at-home and in-office groups, respectively. Predictors for side effects were tooth sensitivity, surface loss and gingivitis when observed at inclusion. Treatment-related predictors were bleaching concentration and contact between tray and gingiva. Conclusions...

  20. An Effective Ostrich Oil Bleaching Technique Using Peroxide Value as an Indicator

    Directory of Open Access Journals (Sweden)

    Gan Seng Chiew

    2011-07-01

    Full Text Available Ostrich oil has been used extensively in the cosmetic and pharmaceutical industries. However, rancidity causes undesirable chemical changes in flavour, colour, odour and nutritional value. Bleaching is an important process in refining ostrich oil. Bleaching refers to the removal of certain minor constituents (colour pigments, free fatty acid, peroxides, odour and non-fatty materials from crude fats and oils to yield purified glycerides. There is a need to optimize the bleaching process of crude ostrich oil prior to its use for therapeutic purposes. The objective of our study was to establish an effective method to bleach ostrich oil using peroxide value as an indicator of refinement. In our study, we showed that natural earth clay was better than bentonite and acid-activated clay to bleach ostrich oil. It was also found that 1 hour incubation at a 150 °C was suitable to lower peroxide value by 90%. In addition, the nitrogen trap technique in the bleaching process was as effective as the continuous nitrogen flow technique and as such would be the recommended technique due to its cost effectiveness.

  1. Bleaching of the discolored traumatized tooth

    DEFF Research Database (Denmark)

    Dahl, Jon E.; Kopperud, Siemen E.; Pallesen, Ulla

    2018-01-01

    This chapter focuses on the treatment of discolored traumatized teeth, most of them being non-vital and subsequently, endodontically treated. Tooth bleaching based upon hydrogen peroxide as the active agent, applied directly or produced in a chemical reaction from sodium perborate or carbamide pe...

  2. Investigation of bleaching kinetics of the photochromic halogen-copper-cadmium glass

    International Nuclear Information System (INIS)

    Marczuk, K.; Ziemba, B.

    1997-01-01

    The curves of the isothermal glass bleaching kinetics of various conditions of exciting radiation are presented. Different values of radiation power, time of irradiation and temperature of samples were applied. analysis of the relaxation curves made it possible to distinguish three exponential components of the bleaching process with different time constants. For each component the relaxation coefficient has been determined. Basing on temperature dependence of the relaxation coefficients for the isothermal glass bleaching the activation energy for slow (E D = 0.46 eV) and fast (E K = 0.13 eV) colour centre decay process have been determined. (author)

  3. Don't bleach chaotic data

    International Nuclear Information System (INIS)

    Theiler, J.; Eubank, S.

    1993-01-01

    A common first step in time series signal analysis involves digitally filtering the data to remove linear correlations. The residual data is spectrally white (it is ''bleached''), but in principle retains the nonlinear structure of the original time series. It is well known that simple linear autocorrelation can give rise to spurious results in algorithms for estimating nonlinear invariants, such as fractal dimension and Lyapunov exponents. In theory, bleached data avoids these pitfalls. But in practice, bleaching obscures the underlying deterministic structure of a low-dimensional chaotic process. This appears to be a property of the chaos itself, since nonchaotic data are not similarly affected. The adverse effects of bleaching are demonstrated in a series of numerical experiments on known chaotic data. Some theoretical aspects are also discussed

  4. [Assessment of tooth bleaching efficacy with spectrophotometer].

    Science.gov (United States)

    Zhu, Wenhao; Liu, Chang; Pan, Jie

    2014-06-01

    To analyze the changes in CIE L*, a*, and b* at cervical, body, and incisal sites after tooth bleaching by using a spectrophotometer. Sixty-seven intact and healthy maxillary central incisors were in-vestigated. These incisors were darker than A3 according to the Vita Classical shade guide. The CIE tooth shade parameters L*, a*, and b* were simultaneously recorded at three tooth areas (cervical, body, and incisal) with a spectrophotometer before and after tooth bleaching (35%H2O2 coordinating with Beyond whitening accelerator irradiating). The shade dif-ferential (DeltaE) was calculated. ANOVA, paired t-test, and Pearson correlation analysis were used for data analysis. The efficacy rates of tooth bleaching were satisfactory, with 86.6%, 86.6%, and 85.1% in the cervical, body, and incisal sites, respectively. The average values of DeltaE were 5.09, 4.44, and 4.40 in the cervical, body, and incisal sites. Tooth bleaching significantly increased L* and significantly decreased a* and b* in all tooth areas (P spectrophotometer could objectively evaluate the whitening effect of tooth bleaching at the different tooth sites. The tooth bleaching system (35%H202 coordinating with Beyond whitening accelerator irradiating) exerts powerful bleaching actions in most of the tooth areas investigated. The order of tooth bleaching effectiveness is cervicalbody>incisal. Yellow coloration is decreased mainly at the cervical site, and brightness was increased mostly at theincisal site. The effectiveness of tooth bleaching increases as the baseline b* value increases.

  5. Effect of different bleaching strategies on microhardness of a silorane-based composite resin.

    Science.gov (United States)

    Bahari, Mahmoud; Savadi Oskoee, Siavash; Mohammadi, Narmin; Ebrahimi Chaharom, Mohammad Esmaeel; Godrati, Mostafa; Savadi Oskoee, Ayda

    2016-01-01

    Background. Dentists' awareness of the effects of bleaching agents on the surface and mechanical properties of restorative materials is of utmost importance. Therefore, this in vitro study was undertaken to investigate the effects of different bleaching strategies on the microhardness of a silorane-based composite resin. Methods. Eighty samples of a silorane-based composite resin (measuring 4 mm in diameter and 2 mm in thickness) were prepared within acrylic molds. The samples were polished and randomly assigned to 4 groups (n=20). Group 1 (controls) were stored in distilled water for 2 weeks. The samples in group 2 underwent a bleaching procedure with 15% carbamide peroxide for two weeks two hours daily. The samples in group 3 were bleached with 35% hydrogen peroxide twice 5 days apart for 30 minutes each time. The samples in group 4 underwent a bleaching procedure with light-activated 35% hydrogen peroxide under LED light once for 40 minutes. Then the microhardness of the samples was determined using Vickers method. Data were analyzed with one-way ANOVA and post hoc Tukey tests (P bleaching agents significantly decreased microhardness compared to the control group (P 0.05). Conclusion. Bleaching agents decreased microhardness of silorane-based composite resin restorations, the magnitude of which depending on the bleaching strategy used.

  6. Modelling the thermal bleaching of OSL signal in the case of a competition between recombination centres

    International Nuclear Information System (INIS)

    Chruscinska, A.

    2009-01-01

    The thermal bleaching of the optically stimulated luminescence (OSL) has been investigated by computer simulations for a model including three traps and two luminescence centres. The deepest trap is active only during the OSL process. Two other traps are active only during the thermal bleaching. The thermal bleaching effects on the OSL intensity as well as on the OSL curve shape are presented for the wide range of trap and luminescence centre parameters and for the different settings of optical detection window. The conventional OSL curve analysis consisting in decomposition of the OSL curve into first order components is applied to the simulation results and the optical cross section spectra obtained as a result of this analysis are compared with the model assumptions. The simulations show that OSL signal can decrease to undetectable level even when the traps related to this signal are not emptied during thermal bleaching. The residual level of the OSL signal after bleaching process, however, depends strongly on centre parameters and concentrations. The modifications of optical detection spectral window lead to significant changes of bleaching effects. The thermal bleaching influences also the optical cross section spectra obtained as a result of the OSL curve decomposition.

  7. Regeneration of irradiated optical fibres by photo-bleaching?

    International Nuclear Information System (INIS)

    Henschel, H.; Koehn, O.

    1999-01-01

    It is known that a light power between 0,1 and 20 μW caused bleaching of colour centres, which implies a reduction of induced loss. Older fibres especially those with a core made of undoped, low OH silica, experience tremendous photo-bleaching. Light of shorter wavelengths has a higher bleaching efficiency than that of longer wavelengths and same light intensity. The investigations have demonstrated that the injection of photo-bleaching light of shorter wavelength and higher intensity can distinctly decrease the radiation-induced loss of Ge-doped fibres, especially at low temperatures. Another possibility to apply photo-bleaching by short wavelength is to regenerate fibres that are permanently installed in radiation environments. Modern undoped multi-mode (MM) step index (Si), Ge-doped MM graded index (Gi) and Ge-doped single-mode (SM) fibres that had been irradiated were submitted to bleaching light. In this article it is shown how loss reduction and necessary bleaching time depend on wavelength and intensity of the bleaching light, on fibre length (bleaching time) and on radiation dose. These results are promising for the regeneration of optical fibres in facilities where the fibres cannot be replaced easily by new ones. (A.C.)

  8. Clinical and patient reported outcomes of bleaching effectiveness.

    Science.gov (United States)

    Klaric Sever, Eva; Budimir, Zrinka; Cerovac, Matea; Stambuk, Mario; Par, Matej; Negovetic Vranic, Dubravka; Tarle, Zrinka

    2018-01-01

    The objective of this study is to evaluate clinical and patient reported outcomes of different bleaching products. Thirty participants were randomly divided into three bleaching groups (n = 10). Bleaching was performed with high concentrations of hydrogen peroxide (HP) - Boost (40%) and Dash (30%), and with prefabricated splints Bite&White (6% HP). Tooth colour was measured before, immediately after, and 1 and 6 months after the bleaching by using classical shade guide and spectrophotometer. Tooth hypersensitivity was self-rated by patients on the Wong-Baker's face scale. Patient satisfaction was evaluated on a 7-point Likert-type scales that measured perceived performance and importance of different characteristics of bleaching treatment. All products were effective in teeth colour change (ΔE > 3.3), which was significantly higher for Boost (p = .016) and Dash (p = .024) than Bite&White treatment. Perception of hypersensitivity was the highest in Boost group, followed by Dash and Bite&White treatment. Most of the patients were satisfied with final tooth colour, length and comfort during treatment, but were dissatisfied with the stability of bleached tooth colour. Materials with the higher concentrations of bleaching agent demonstrated greater bleaching effectiveness than at-home bleaching product, but also a greater hypersensitivity. Lengthening the treatment process, but achieving a more stable tooth colour may improve the perceived value of a bleaching service.

  9. Susceptibility of Enamel Treated with Bleaching Agents to Mineral Loss after Cariogenic Challenge

    Directory of Open Access Journals (Sweden)

    Hüseyin Tezel

    2011-01-01

    Full Text Available Objectives. Controversial reports exist whether bleaching agents cause a susceptibility to demineralization. The aim of this study was to compare the calcium loss of enamel treated with different bleaching agents and activation methods. Method and Materials. The specimens obtained from human premolars were treated in accordance with manufacturer protocols; 10% carbamide peroxide, 38% hydrogen peroxide light-activated, 38% hydrogen peroxide laser-activated, and no treatment (control. After cariogenic challenge calcium concentrations were determined by Inductively Coupled Plasma Mass Spectrometry. Results. No differences were found between the calcium loss of the laser-activated group and 10% carbamide peroxide group (>0.05. However, the differences between laser-activated and control groups were statistically significant (0.05. On the other hand, the light-activated group showed a significantly higher calcium loss compared with the other groups (<0.05. Conclusions. The results show that bleaching agents may cause calcium loss but it seems to be a negligible quantity for clinical aspects.

  10. Coral bleaching response index: a new tool to standardize and compare susceptibility to thermal bleaching.

    Science.gov (United States)

    Swain, Timothy D; Vega-Perkins, Jesse B; Oestreich, William K; Triebold, Conrad; DuBois, Emily; Henss, Jillian; Baird, Andrew; Siple, Margaret; Backman, Vadim; Marcelino, Luisa

    2016-07-01

    As coral bleaching events become more frequent and intense, our ability to predict and mitigate future events depends upon our capacity to interpret patterns within previous episodes. Responses to thermal stress vary among coral species; however the diversity of coral assemblages, environmental conditions, assessment protocols, and severity criteria applied in the global effort to document bleaching patterns creates challenges for the development of a systemic metric of taxon-specific response. Here, we describe and validate a novel framework to standardize bleaching response records and estimate their measurement uncertainties. Taxon-specific bleaching and mortality records (2036) of 374 coral taxa (during 1982-2006) at 316 sites were standardized to average percent tissue area affected and a taxon-specific bleaching response index (taxon-BRI) was calculated by averaging taxon-specific response over all sites where a taxon was present. Differential bleaching among corals was widely variable (mean taxon-BRI = 25.06 ± 18.44%, ±SE). Coral response may differ because holobionts are biologically different (intrinsic factors), they were exposed to different environmental conditions (extrinsic factors), or inconsistencies in reporting (measurement uncertainty). We found that both extrinsic and intrinsic factors have comparable influence within a given site and event (60% and 40% of bleaching response variance of all records explained, respectively). However, when responses of individual taxa are averaged across sites to obtain taxon-BRI, differential response was primarily driven by intrinsic differences among taxa (65% of taxon-BRI variance explained), not conditions across sites (6% explained), nor measurement uncertainty (29% explained). Thus, taxon-BRI is a robust metric of intrinsic susceptibility of coral taxa. Taxon-BRI provides a broadly applicable framework for standardization and error estimation for disparate historical records and collection of novel

  11. Identifying well-bleached quartz using the different bleaching rates of quartz and feldspar luminescence signals

    DEFF Research Database (Denmark)

    Murray, A.S.; Thomsen, Kristina Jørkov; Masuda, N.

    2012-01-01

    When dating older sedimentary deposits using quartz, there are no unambiguous methods for identifying the presence of incomplete bleaching. Current statistical analysis of dose distributions depends entirely on the assumption that incomplete bleaching and mixing are the main causes of any excess...... dispersion in the distribution; the only existing way to test this assumption is using independent age control. Here we suggest a new approach to this question, based on the differential bleaching rates of quartz and feldspar luminescence signals. We first present data that confirm the differences...... in relative bleaching rates of quartz optically stimulated luminescence (OSL) and feldspar luminescence stimulated at 50 °C by infrared light (IR50) and feldspar luminescence stimulated at 290 °C by infrared light after a stimulation at 50 °C (pIRIR290), and use recently deposited samples to determine...

  12. Mass coral bleaching in the northern Persian Gulf, 2012

    Directory of Open Access Journals (Sweden)

    Javid Kavousi

    2014-09-01

    Full Text Available Coral bleaching events due to elevated temperatures are increasing in both frequency and magnitude worldwide. Mass bleaching was recorded at five sites in the northern Persian Gulf during August and September 2012. Based on available seawater temperature data from field, satellite and previous studies, we suggest that the coral bleaching threshold temperature in the northern Persian Gulf is between 33.5 and 34°C, which is about 1.5 to 2.5°C lower than that in the southern part. To assess the bleaching effects, coral genera counted during 60-minute dives were categorized into four groups including healthy, slightly bleached ( 50% bleached tissue and fully bleached colonies. The anomalously high sea surface temperature resulted in massive coral bleaching (~84% coral colonies affected. Acropora spp. colonies, which are known as the most vulnerable corals to thermal stress, were less affected by the bleaching than massive corals, such as Porites, which are among the most thermo-tolerant corals. Turbid waters, suggested as coral refugia against global warming, did not protect corals in this study since most affected corals were found in the most turbid waters. The 2012 bleaching in the northern Persian Gulf was relatively strong from the viewpoint of coral bleaching severity. Long-term monitoring is needed to understand the actual consequences of the bleaching event on the coral reefs and communities.

  13. Study on Bleaching Technology of Cotton Fabric with Sodium Percarbonate

    OpenAIRE

    Li Zhi; Wang Yanling; Wang Zhichao

    2016-01-01

    Bleach cotton fabric with sodium percarbonate solution. Analyse of the effect of the concentration of sodium percarbonate solution, bleaching time, bleaching temperature and the light radiation on the bleaching effect of fabric.The result shows that increasing concentrations of percarbonate,increasing the bleaching time , raising the bleaching temperature and the UV irradiation may whiten the cotton fabric.The most suitable conditions for the bleaching process is concentration of sodium perca...

  14. Differential gene expression during thermal stress and bleaching in the Caribbean coral Montastraea faveolata.

    Science.gov (United States)

    DeSalvo, M K; Voolstra, C R; Sunagawa, S; Schwarz, J A; Stillman, J H; Coffroth, M A; Szmant, A M; Medina, M

    2008-09-01

    The declining health of coral reefs worldwide is likely to intensify in response to continued anthropogenic disturbance from coastal development, pollution, and climate change. In response to these stresses, reef-building corals may exhibit bleaching, which marks the breakdown in symbiosis between coral and zooxanthellae. Mass coral bleaching due to elevated water temperature can devastate coral reefs on a large geographical scale. In order to understand the molecular and cellular basis of bleaching in corals, we have measured gene expression changes associated with thermal stress and bleaching using a complementary DNA microarray containing 1310 genes of the Caribbean coral Montastraea faveolata. In a first experiment, we identified differentially expressed genes by comparing experimentally bleached M. faveolata fragments to control non-heat-stressed fragments. In a second experiment, we identified differentially expressed genes during a time course experiment with four time points across 9 days. Results suggest that thermal stress and bleaching in M. faveolata affect the following processes: oxidative stress, Ca(2+) homeostasis, cytoskeletal organization, cell death, calcification, metabolism, protein synthesis, heat shock protein activity, and transposon activity. These results represent the first medium-scale transcriptomic study focused on revealing the cellular foundation of thermal stress-induced coral bleaching. We postulate that oxidative stress in thermal-stressed corals causes a disruption of Ca(2+) homeostasis, which in turn leads to cytoskeletal and cell adhesion changes, decreased calcification, and the initiation of cell death via apoptosis and necrosis.

  15. Coral bleaching at Little Cayman, Cayman Islands 2009

    Science.gov (United States)

    van Hooidonk, Ruben J.; Manzello, Derek P.; Moye, Jessica; Brandt, Marilyn E.; Hendee, James C.; McCoy, Croy; Manfrino, Carrie

    2012-06-01

    The global rise in sea temperature through anthropogenic climate change is affecting coral reef ecosystems through a phenomenon known as coral bleaching; that is, the whitening of corals due to the loss of the symbiotic zooxanthellae which impart corals with their characteristic vivid coloration. We describe aspects of the most prevalent episode of coral bleaching ever recorded at Little Cayman, Cayman Islands, during the fall of 2009. The most susceptible corals were found to be, in order, Siderastrea siderea, Montastraea annularis, and Montastraea faveolata, while Diplora strigosa and Agaricia spp. were less so, yet still showed considerable bleaching prevalence and severity. Those found to be least susceptible were Porites porites, Porites astreoides, and Montastraea cavernosa. These observations and other reported observations of coral bleaching, together with 29 years (1982-2010) of satellite-derived sea surface temperatures, were used to optimize bleaching predictions at this location. To do this a Degree Heating Weeks (DHW) and Peirce Skill Score (PSS) analysis was employed to calculate a local bleaching threshold above which bleaching was expected to occur. A threshold of 4.2 DHW had the highest skill, with a PSS of 0.70. The method outlined here could be applied to other regions to find the optimal bleaching threshold and improve bleaching predictions.

  16. Mass coral bleaching in 2010 in the southern Caribbean.

    Science.gov (United States)

    Alemu I, Jahson Berhane; Clement, Ysharda

    2014-01-01

    Ocean temperatures are increasing globally and the Caribbean is no exception. An extreme ocean warming event in 2010 placed Tobago's coral reefs under severe stress resulting in widespread coral bleaching and threatening the livelihoods that rely on them. The bleaching response of four reef building taxa was monitored over a six month period across three major reefs systems in Tobago. By identifying taxa resilient to bleaching we propose to assist local coral reef managers in the decision making process to cope with mass bleaching events. The bleaching signal (length of exposure to high ocean temperatures) varied widely between the Atlantic and Caribbean reefs, but regardless of this variation most taxa bleached. Colpophyllia natans, Montastraea faveolata and Siderastrea siderea were considered the most bleaching vulnerable taxa. Interestingly, reefs with the highest coral cover showed the greatest decline reef building taxa, and conversely, reefs with the lowest coral cover showed the most bleaching but lowest change in coral cover with little algal overgrowth post-bleaching.

  17. Mass Coral Bleaching in 2010 in the Southern Caribbean

    Science.gov (United States)

    Alemu I, Jahson Berhane; Clement, Ysharda

    2014-01-01

    Ocean temperatures are increasing globally and the Caribbean is no exception. An extreme ocean warming event in 2010 placed Tobago's coral reefs under severe stress resulting in widespread coral bleaching and threatening the livelihoods that rely on them. The bleaching response of four reef building taxa was monitored over a six month period across three major reefs systems in Tobago. By identifying taxa resilient to bleaching we propose to assist local coral reef managers in the decision making process to cope with mass bleaching events. The bleaching signal (length of exposure to high ocean temperatures) varied widely between the Atlantic and Caribbean reefs, but regardless of this variation most taxa bleached. Colpophyllia natans, Montastraea faveolata and Siderastrea siderea were considered the most bleaching vulnerable taxa. Interestingly, reefs with the highest coral cover showed the greatest decline reef building taxa, and conversely, reefs with the lowest coral cover showed the most bleaching but lowest change in coral cover with little algal overgrowth post-bleaching. PMID:24400078

  18. Enamel alteration following tooth bleaching and remineralization.

    Science.gov (United States)

    Coceska, Emilija; Gjorgievska, Elizabeta; Coleman, Nichola J; Gabric, Dragana; Slipper, Ian J; Stevanovic, Marija; Nicholson, John W

    2016-06-01

    The purpose of this study was to compare the effects of professional tooth whitening agents containing highly concentrated hydrogen peroxide (with and without laser activation), on the enamel surface; and the potential of four different toothpastes to remineralize any alterations. The study was performed on 50 human molars, divided in two groups: treated with Opalescence(®) Boost and Mirawhite(®) Laser Bleaching. Furthermore, each group was divided into five subgroups, a control one and 4 subgroups remineralized with: Mirasensitive(®) hap+, Mirawhite(®) Gelleѐ, GC Tooth Mousse™ and Mirafluor(®) C. The samples were analysed by SEM/3D-SEM-micrographs, SEM/EDX-qualitative analysis and SEM/EDX-semiquantitative analysis. The microphotographs show that both types of bleaching cause alterations: emphasized perikymata, erosions, loss of interprizmatic substance; the laser treatment is more aggressive and loss of integrity of the enamel is determined by shearing off the enamel rods. In all samples undergoing remineralization deposits were observed, those of toothpastes based on calcium phosphate technologies seem to merge with each other and cover almost the entire surface of the enamel. Loss of integrity and minerals were detected only in the line-scans of the sample remineralized with GC Tooth Mousse™. The semiquantitative EDX analysis of individual elements in the surface layer of the enamel indicates that during tooth-bleaching with HP statistically significant loss of Na and Mg occurs, whereas the bleaching in combination with a laser leads to statistically significant loss of Ca and P. The results undoubtedly confirm that teeth whitening procedures lead to enamel alterations. In this context, it must be noted that laser bleaching is more aggressive for dental substances. However, these changes are reversible and can be repaired by application of remineralization toothpastes. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

  19. Global warming and recurrent mass bleaching of corals

    Science.gov (United States)

    Hughes, Terry P.; Kerry, James T.; Álvarez-Noriega, Mariana; Álvarez-Romero, Jorge G.; Anderson, Kristen D.; Baird, Andrew H.; Babcock, Russell C.; Beger, Maria; Bellwood, David R.; Berkelmans, Ray; Bridge, Tom C.; Butler, Ian R.; Byrne, Maria; Cantin, Neal E.; Comeau, Steeve; Connolly, Sean R.; Cumming, Graeme S.; Dalton, Steven J.; Diaz-Pulido, Guillermo; Eakin, C. Mark; Figueira, Will F.; Gilmour, James P.; Harrison, Hugo B.; Heron, Scott F.; Hoey, Andrew S.; Hobbs, Jean-Paul A.; Hoogenboom, Mia O.; Kennedy, Emma V.; Kuo, Chao-Yang; Lough, Janice M.; Lowe, Ryan J.; Liu, Gang; McCulloch, Malcolm T.; Malcolm, Hamish A.; McWilliam, Michael J.; Pandolfi, John M.; Pears, Rachel J.; Pratchett, Morgan S.; Schoepf, Verena; Simpson, Tristan; Skirving, William J.; Sommer, Brigitte; Torda, Gergely; Wachenfeld, David R.; Willis, Bette L.; Wilson, Shaun K.

    2017-03-01

    During 2015-2016, record temperatures triggered a pan-tropical episode of coral bleaching, the third global-scale event since mass bleaching was first documented in the 1980s. Here we examine how and why the severity of recurrent major bleaching events has varied at multiple scales, using aerial and underwater surveys of Australian reefs combined with satellite-derived sea surface temperatures. The distinctive geographic footprints of recurrent bleaching on the Great Barrier Reef in 1998, 2002 and 2016 were determined by the spatial pattern of sea temperatures in each year. Water quality and fishing pressure had minimal effect on the unprecedented bleaching in 2016, suggesting that local protection of reefs affords little or no resistance to extreme heat. Similarly, past exposure to bleaching in 1998 and 2002 did not lessen the severity of bleaching in 2016. Consequently, immediate global action to curb future warming is essential to secure a future for coral reefs.

  20. Bleaching and recovery of a phototrophic bioeroding sponge

    Science.gov (United States)

    Marlow, Joseph; Davy, Simon K.; Shaffer, Megan; Haris, Abdul; Bell, James J.

    2018-06-01

    In the Wakatobi region of Indonesia, a prolonged period of elevated water temperature in 2016 caused extensive coral bleaching and mortality. Unusually, bleaching was also observed in the bioeroding sponge Cliona aff. viridis, with affected sponges expelling 99% of their Symbiodinium. Bleaching surveys of C. aff. viridis were conducted 6 weeks apart, coinciding with a 0.8 °C drop in water temperature. Over this period, bleaching prevalence dropped from 73.9% (± 9.9 SE) to 25.7% (± 5.8 SE), and bleaching severity dropped from 25.95% (± 4.5 SE) to 11.54% (± 1.9 SE) of sponge tissue. Over the same period, monitored bleached sponges showed an 81% drop in bleaching severity, but also a 13% reduction in overall sponge size. Our results show that while the clionaid- Symbiodinium relationship is susceptible to break down under thermal stress, rapid recovery can occur, although incurring some partial host mortality.

  1. Global warming and recurrent mass bleaching of corals.

    Science.gov (United States)

    Hughes, Terry P; Kerry, James T; Álvarez-Noriega, Mariana; Álvarez-Romero, Jorge G; Anderson, Kristen D; Baird, Andrew H; Babcock, Russell C; Beger, Maria; Bellwood, David R; Berkelmans, Ray; Bridge, Tom C; Butler, Ian R; Byrne, Maria; Cantin, Neal E; Comeau, Steeve; Connolly, Sean R; Cumming, Graeme S; Dalton, Steven J; Diaz-Pulido, Guillermo; Eakin, C Mark; Figueira, Will F; Gilmour, James P; Harrison, Hugo B; Heron, Scott F; Hoey, Andrew S; Hobbs, Jean-Paul A; Hoogenboom, Mia O; Kennedy, Emma V; Kuo, Chao-Yang; Lough, Janice M; Lowe, Ryan J; Liu, Gang; McCulloch, Malcolm T; Malcolm, Hamish A; McWilliam, Michael J; Pandolfi, John M; Pears, Rachel J; Pratchett, Morgan S; Schoepf, Verena; Simpson, Tristan; Skirving, William J; Sommer, Brigitte; Torda, Gergely; Wachenfeld, David R; Willis, Bette L; Wilson, Shaun K

    2017-03-15

    During 2015-2016, record temperatures triggered a pan-tropical episode of coral bleaching, the third global-scale event since mass bleaching was first documented in the 1980s. Here we examine how and why the severity of recurrent major bleaching events has varied at multiple scales, using aerial and underwater surveys of Australian reefs combined with satellite-derived sea surface temperatures. The distinctive geographic footprints of recurrent bleaching on the Great Barrier Reef in 1998, 2002 and 2016 were determined by the spatial pattern of sea temperatures in each year. Water quality and fishing pressure had minimal effect on the unprecedented bleaching in 2016, suggesting that local protection of reefs affords little or no resistance to extreme heat. Similarly, past exposure to bleaching in 1998 and 2002 did not lessen the severity of bleaching in 2016. Consequently, immediate global action to curb future warming is essential to secure a future for coral reefs.

  2. Assessment of acute phase proteins and oxidative stress status of Nigerians using bleaching agents

    International Nuclear Information System (INIS)

    Akibinu, M.O.; Arinola, O.G.; Afolabi, K.A.

    2010-01-01

    The disruption of primary innate immune function of the epidermal layer of the skin accounts for the susceptibility of individuals using bleaching agents to localized or systemic infections. This subverted innate immunity in these people may lead to other pathological conditions. The resultant effects of skin bleaching and phagocytes activation in response to infections have not been studied in Nigerians using bleaching agents. The present study therefore assessed the levels of C-reactive protein (CRP), albumin, total antioxidant potential (TAP), total plasma peroxides (TPP), oxidative stress index (OSI) and malonaldehyde (MDA) in the users bleaching agents. Thirty (30) people who had used bleaching agents for average of 4.9 + 1.2 years participated in this study. They were recruited from various schools and markets within the city of Ibadan, Oyo State, Nigeria. Thirty apparently healthy staffs of University College Hospital Ibadan, Ibaadan, Nigeria, who had never used bleaching agents served as controls. All the subjects used for this study had no metabolic abnormality and tested negative to both HIV and hepatitis B infections. The mean value of TAP (p 0.20) when compared with the controls. Oxidative stress and chronic inflammation are possible consequences of skin bleaching. The users of skin bleaching agents may need antioxidant therapies to avert the risks of oxidative stress. (author)

  3. Application of TAED/H2O2 system for low temperature bleaching of crude cellulose extracted from jute fiber

    Science.gov (United States)

    Wen, Zuoqiang; Zou, Linbo; Wang, Weiming

    2018-03-01

    Tetraacetylethylenediamine (TAED) activated hydrogen peroxide system had been applied for bleaching of crude cellulose extracted from jute fiber. Comparing with conventional hydrogen peroxide bleaching system, those results showed that bleaching temperature and time could be effectively reduced, and a preferable whiteness could be produced under faint alkaline condition. And the optimum conditions for activated bleaching system could be summarized as molar ratio of H2O2/TAED 1:0.7, pH 8, pure hydrogen peroxide 0.09 mol/L, temperature 70 °C and time 60min.

  4. Efficacy and cytotoxicity of a bleaching gel after short application times on dental enamel.

    Science.gov (United States)

    Soares, Diana Gabriela; Ribeiro, Ana Paula Dias; da Silveira Vargas, Fernanda; Hebling, Josimeri; de Souza Costa, Carlos Alberto

    2013-11-01

    This study aimed to evaluate and correlate the efficacy and cytotoxicity of a 35 % hydrogen peroxide (HP) bleaching gel after different application times on dental enamel. Enamel/dentin disks in artificial pulp chambers were placed in wells containing culture medium. The following groups were formed: G1, control (no bleaching); G2 and G3, three or one 15-min bleaching applications, respectively; and G4 and G5, three or one 5-min bleaching applications, respectively. Extracts (culture medium with bleaching gel components) were applied for 60 min on cultured odontoblast-like MDPC-23 cells. Cell metabolism (methyl tetrazolium assay) (Kruskal-Wallis/Mann-Whitney; α = 5 %) and cell morphology (scanning electron microscopy) were analyzed immediately after the bleaching procedures and the trans-enamel and trans-dentinal HP diffusion quantified (one-way analysis of variance/Tukey's test; α = 5 %). The alkaline phosphatase (ALP) activity was evaluated 24 h after the contact time of the extracts with the cells (Kruskal-Wallis/Mann-Whitney; α = 5 %). Tooth color was analyzed before and 24 h after bleaching using a spectrophotometer according to the Commission Internationale de l'Eclairage L*a*b* system (Kruskal-Wallis/Mann-Whitney; α = 0.05). Significant difference (p 0.05). The lowest amount of HP diffusion was observed in G5 (p 0.05). HP diffusion through dental tissues and its cytotoxic effects were proportional to the contact time of the bleaching gel with enamel. However, shorter bleaching times reduced bleaching efficacy. Shortening the in-office tooth bleaching time could be an alternative to minimize the cytotoxic effects of this clinical procedure to pulp tissue. However, the reduced time of bleaching agent application on enamel may not provide adequate esthetic outcome.

  5. Quantifying bleaching for zero-age fluvial sediment: A Bayesian approach

    International Nuclear Information System (INIS)

    Cunningham, Alastair C.; Evans, Mary; Knight, Jasper

    2015-01-01

    Luminescence dating of sediment requires the sand grains to have been exposed to sunlight prior to their most recent burial. Under fluvial transport, the amount of sunlight exposure may not always be sufficient to reset the luminescence signal, a phenomenon known as ‘partial bleaching'. The extent of bleaching is dependent on a combination of geomorphic, sedimentological and fluvial processes. If bleaching can be quantified, and the relationship with these processes understood, it could potentially be used as a new environmental proxy for changes in the dynamics of river systems. Here, we use a recently developed statistical model to evaluate the extent of bleaching, by inferring the proportion of well-bleached grains in the small-aliquot population. We sampled low-flow and flood deposits at a single site on the River Sabie, South Africa. We show that the low-flow sediment is almost perfectly bleached (>80% of grains well bleached), while sediment at flood elevations is partially bleached (20–70 % of grains well bleached). The degree of bleaching may show a relationship with flood magnitude as defined by elevation above normal river level, and we speculate on the causes of variability in bleaching between flood samples. - Highlights: • We sampled modern river sediment from low-flow and flood elevations. • The unbleached OSL dose was measured. • Bayesian methods can estimate the proportion of well-bleached grains. • Low-flow sediments are well bleached; flood deposits are poorly bleached.

  6. Component resolved bleaching study in natural calcium fluoride using CW-OSL, LM-OSL and residual TL glow curves after bleaching

    International Nuclear Information System (INIS)

    Angeli, Vasiliki; Polymeris, George S.; Sfampa, Ioanna K.; Tsirliganis, Nestor C.; Kitis, George

    2017-01-01

    Natural calcium fluoride has been commonly used as thermoluminescence (TL) dosimeter due to its high luminescence intensity. The aim of this work includes attempting a correlation between specific TL glow curves after bleaching and components of linearly modulated optically stimulated luminescence (LM-OSL) as well as continuous wave OSL (CW-OSL). A component resolved analysis was applied to both integrated intensity of the RTL glow curves and all OSL decay curves, by using a Computerized Glow-Curve De-convolution (CGCD) procedure. All CW-OSL and LM-OSL components are correlated to the decay components of the integrated RTL signal, apart from two RTL components which cannot be directly correlated with either LM-OSL or CW-OSL component. The unique, stringent criterion for this correlation deals with the value of the decay constant λ of each bleaching component. There is only one, unique bleaching component present in all three luminescence entities which were the subject of the present study, indicating that each TL trap yields at least three different bleaching components; different TL traps can indicate bleaching components with similar values. According to the data of the present work each RTL bleaching component receives electrons from at least two peaks. The results of the present study strongly suggest that the traps that contribute to TL and OSL are the same. - Highlights: • A component resolved bleaching study was attempted to CaF_2:N in terms of CW-OSL, LM-OSL and RTL. • Bleaching decay constants originating from different TL peaks yield overlapping values. • Three to five individual components were used in order to describe the bleaching behavior in all luminescence entities. • There is only one, unique bleaching component present in all three luminescence entities.

  7. Spectrophotometric and computerized evaluation of tooth bleaching employing 10 different home-bleaching procedures: In-vitro study

    Science.gov (United States)

    Peskersoy, Cem; Tetik, Ayhan; Ozturk, Veli Ozgen; Gokay, Necmi

    2014-01-01

    Objective: The aim of this in-vitro study was to evaluate the efficacy of bleaching products, determine the applicability and validation of the measurement methods. Materials and Methods: Freshly extracted 110 human incisor teeth were stained with whole blood and hemolysate solution prior to the application of 10 different home-bleaching products. Spectrophotometric measurements of the tooth shades were performed for each specimen before and after bleaching at the 1st, 3rd, 7th, and 14 days. Differences in lightness (Δl), chroma (Δc), hue (Δh) values and shade changes were measured to evaluate process. Computerized digital imaging analyses to determine the color changes were performed with Photoshop CS4 software (Adobe, San Jose, CA, USA). Statistical analyses were performed with analysis of variance, Scheffe and Tukey tests. Results: In all of the test groups regardless of the material used, a significant increase in lightness and hue, and decrease of chroma were observed, as compared to the control group. After recommended bleaching applications, Δl and Δh values respectively increased in group Zaris White and Brite (ZWB) and group Pola Night and Δc values showed significant decrease in groups ZWB and Rembrandt REM3 (P bleaching systems showed slower but almost permanent bleaching effect likewise office-based methods. Both software and spectrophotometric analyses have advantages such as evaluating the results objectively and numerically, also treatment outcomes could be preserved. PMID:25512738

  8. Incorporating adaptive responses into future projections of coral bleaching.

    Science.gov (United States)

    Logan, Cheryl A; Dunne, John P; Eakin, C Mark; Donner, Simon D

    2014-01-01

    Climate warming threatens to increase mass coral bleaching events, and several studies have projected the demise of tropical coral reefs this century. However, recent evidence indicates corals may be able to respond to thermal stress though adaptive processes (e.g., genetic adaptation, acclimatization, and symbiont shuffling). How these mechanisms might influence warming-induced bleaching remains largely unknown. This study compared how different adaptive processes could affect coral bleaching projections. We used the latest bias-corrected global sea surface temperature (SST) output from the NOAA/GFDL Earth System Model 2 (ESM2M) for the preindustrial period through 2100 to project coral bleaching trajectories. Initial results showed that, in the absence of adaptive processes, application of a preindustrial climatology to the NOAA Coral Reef Watch bleaching prediction method overpredicts the present-day bleaching frequency. This suggests that corals may have already responded adaptively to some warming over the industrial period. We then modified the prediction method so that the bleaching threshold either permanently increased in response to thermal history (e.g., simulating directional genetic selection) or temporarily increased for 2-10 years in response to a bleaching event (e.g., simulating symbiont shuffling). A bleaching threshold that changes relative to the preceding 60 years of thermal history reduced the frequency of mass bleaching events by 20-80% compared with the 'no adaptive response' prediction model by 2100, depending on the emissions scenario. When both types of adaptive responses were applied, up to 14% more reef cells avoided high-frequency bleaching by 2100. However, temporary increases in bleaching thresholds alone only delayed the occurrence of high-frequency bleaching by ca. 10 years in all but the lowest emissions scenario. Future research should test the rate and limit of different adaptive responses for coral species across latitudes and

  9. Large-scale bleaching of corals on the Great Barrier Reef.

    Science.gov (United States)

    Hughes, T P; Kerry, J T; Simpson, T

    2018-02-01

    In 2015-2016, record temperatures triggered a pan-tropical episode of coral bleaching. In the southern hemisphere summer of March-April 2016, we used aerial surveys to measure the level of bleaching on 1,156 individual reefs throughout the 2,300 km length of the Great Barrier Reef, the world's largest coral reef system. The accuracy of the aerial scores was ground-truthed with detailed underwater surveys of bleaching at 260 sites (104 reefs), allowing us to compare aerial and underwater bleaching data with satellite-derived temperatures and with associated model predictions of bleaching. The severity of bleaching on individual reefs in 2016 was tightly correlated with the level of local heat exposure: the southernmost region of the Great Barrier Reef escaped with only minor bleaching because summer temperatures there were close to average. Gradients in nutrients and turbidity from inshore to offshore across the Great Barrier Reef had minimal effect on the severity of bleaching. Similarly, bleaching was equally severe on reefs that are open or closed to fishing, once the level of satellite-derived heat exposure was accounted for. The level of post-bleaching mortality, measured underwater after 7-8 months, was tightly correlated with the aerial scores measured at the peak of bleaching. Similarly, reefs with a high aerial bleaching score also experienced major shifts in species composition due to extensive mortality of heat-sensitive species. Reefs with low bleaching scores did not change in composition, and some showed minor increases in coral cover. Two earlier mass bleaching events occurred on the Great Barrier Reef in 1998 and 2002, that were less severe than 2016. In 2016, bleaching, compared to 42% in 2002 and 44% in 1998. Conversely, the proportion of reefs that were severely bleached (>60% of corals affected) was four times higher in 2016. The geographic footprint of each of the three events is distinctive, and matches satellite-derived sea surface

  10. Clean Bleaching Engineering Practice for Bagasse Pulp: Totally Chlorine-Free and Elemental Chlorine-Free Bleaching Realized with the Same Production Line

    Directory of Open Access Journals (Sweden)

    Zhi Li

    2015-03-01

    Full Text Available The experimental research, process design principles, and engineering practice of a bagasse pulp production line that could run both totally chlorine-free (OPQ(PO and elemental chlorine-free (OPD(EOP bleaching sequences are discussed in this paper. Under specified process conditions, the oxygen delignification rate was up to 50% and the brightness of unbleached pulp increased. The (OPQ(PO sequence bleached pulp had a brightness of 83.1% ISO and an intrinsic viscosity of 888 mL/g, and the (OPD(EOP sequence bleached pulp had a brightness of 85.7% ISO and an intrinsic viscosity of 905 mL/g. Pulp quality produced from both bleaching sequences was better than pulp bleached by the chlorination, alkaline extraction, and hypochlorite (CEH sequence. The wastewater was discharged only from the Q or D stage, and the chemical oxygen demand (COD of Q or D stage was about 650 mg/L or 1100 mg/L, respectively. It was easy to alternate between these two bleaching sequences, and the bleached pulp quality from these sequences was stable.

  11. 40 CFR 63.445 - Standards for the bleaching system.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 9 2010-07-01 2010-07-01 false Standards for the bleaching system. 63... Standards for Hazardous Air Pollutants from the Pulp and Paper Industry § 63.445 Standards for the bleaching system. (a) Each bleaching system that does not use any chlorine or chlorinated compounds for bleaching...

  12. Spatial consequences of bleaching adaptation in cat retinal ganglion cells.

    Science.gov (United States)

    Bonds, A B; Enroth-Cugell, C

    1981-01-01

    1. Experiments were conducted to study the effects of localized bleaching on the centre responses of rod-driven cat retinal ganglion cells. 2. Stimulation as far as 2 degrees from the bleaching site yielded responses which were reduced nearly as much as those generated at the bleaching site. Bleaching in the receptive field middle reduced responsiveness at a site 1 degrees peripheral more than bleaching at that peripheral site itself. 3. The effectiveness of a bleach in reducing centre responsiveness is related to the sensitivity of the region in which the bleach is applied. 4. Response reduction after a 0.2 degree bleach followed the same temporal pattern for concentric test spots of from 0.2 to 1.8 degrees in diameter, implying a substantially uniform spread of adaptation within these bounds. 5. A linear trade-off between fraction of rhodopsin and area bleached over a range of 8:1 yields the same pattern of response reduction, implying that the non-linear nature of bleaching adaptation is a property of the adaptation pool rather than independent photoreceptors. PMID:7320894

  13. Inhibition of photosynthesis and bleaching of zooxanthellae by the coral pathogen Vibrio shiloi.

    Science.gov (United States)

    Ben-Haim, Y; Banim, E; Kushmaro, A; Loya, Y; Rosenberg, E

    1999-06-01

    Vibrio shiloi is the causative agent of bleaching (loss of endosymbiotic zooxanthellae) of the coral Oculina patagonica in the Mediterranean Sea. To obtain information on the mechanism of bleaching, we examined the effect of secreted material (AK1-S) produced by V. shiloi on zooxanthellae isolated from corals. AK1-S caused a rapid inhibition of photosynthesis of the algae, as measured with a Mini-PAM fluorometer. The inhibition of photosynthesis was caused by (i) ammonia produced during the growth of V. shiloi on protein-containing media and (ii) a non-dialysable heat-resistant factor. This latter material did not inhibit photosynthesis of the algae by itself but, when added to different concentrations of NH4Cl, enhanced the inhibition approximately two- to threefold. Ammonia and the enhancer were effective to different degrees on zooxanthellae isolated from four species of coral examined. In addition to the rapid inhibition of photosynthesis, AK1-S caused bleaching (loss of pigmentation) and lysis of zooxanthellae. Bleaching was more rapid than lysis, reaching a peak (25% bleached algae) after 6 h. The factors in AK1-S responsible for bleaching and lysis were different from those responsible for the inhibition of photosynthesis, because they were heat sensitive, non-dialysable and active in the dark. Thus, the coral pathogen V. shiloi produces an array of extracellular materials that can inhibit photosynthesis, bleach and lyse zooxanthellae.

  14. Activation/waste management

    International Nuclear Information System (INIS)

    Maninger, C.

    1984-10-01

    The selection of materials and the design of the blankets for fusion reactors have significant effects upon the radioactivity generated by neutron activation in the materials. This section considers some aspects of materials selection with respect to waste management. The activation of the materials is key to remote handling requirements for waste, to processing and disposal methods for waste, and to accident severity in waste management operations. In order to realize the desirable evnironmental potentials of fusion power systems, there are at least three major goals for waste management. These are: (a) near-surface burial; (b) disposal on-site of the fusion reactor; (c) acceptable radiation doses at least cost during and after waste management operations

  15. BLEACHING IN VITAL TEETH: A LITERARY REVIEW

    Directory of Open Access Journals (Sweden)

    Felipe Fagundes Soares

    2007-12-01

    Full Text Available Tooth bleaching technique has presented a significant evolution, promoting higher satisfaction and comfort to the patients. Therefore, the aim of this study was to present the bleaching agents and the techniques, discussing advantages and disadvantages of each one, and the effect of these agents in the oral environment. The main agents used in the bleaching technique are the hydrogen peroxide and the carbamide peroxide, promoting the bleaching effect through oxidation of organic compounds. The application of these agents can be made at home or at a doctor office. During treatment, it may occur some adverse effects, such as tooth sensibility, increasing of dental porosity, and some interactions with the restorative material. However, these adverse effects can be eliminated or controlled when the treatment is executed under professional orientation. When the bleaching technique is well indicated and correctly conducted, it is associated with significantly positive results.

  16. A novel paleo-bleaching proxy using boron isotopes and high-resolution laser ablation to reconstruct coral bleaching events

    OpenAIRE

    Dishon, G.; Fisch, J.; Horn, Ingo; Kaczmarek, Karina; Bijma, Jelle; Gruber, D.F.; Nir, O.; Popovich, Y.; Tchernov, D.

    2015-01-01

    Coral reefs occupy only ~ 0.1 percent of the ocean's habitat, but are the most biologically diverse marine ecosystem. In recent decades, coral reefs have experienced a significant global decline due to a variety of causes, one of the major causes being widespread coral bleaching events. During bleaching, the coral expels its symbiotic algae, thereby losing its main source of nutrition generally obtained through photosynthesis. While recent coral bleaching events have been ex...

  17. Bleaching of F-type centres in alkali halides

    International Nuclear Information System (INIS)

    Chandratillake, M.R.; Newton, G.W.A.; Robinson, V.J.

    1984-01-01

    Bleaching of the F band in KCl occurs on pulsing with 532 nm laser light. The bleaching is accompanied by the appearance of an absorption on the red side of the F band. Both bleaching and absorption are transient phenomena, and no permanent bleaching or absorption is observed. The same exponential lifetime of about 5μS was obtained for both bleaching and absorption, and all the features were found to be independent of both temperature (between 200 and 300 K) and the intensity of the analysing light. This eliminates the possibility of a trapped species, such as F - , being responsible. The phenomena are qualitatively different from the bleaching observed at low light intensity, where bleaching of the F band is accompanied by formation of F - , which is thermally stable below 250 K. The most likely explanation of the results is that the high concentration of conduction band electrons following the laser pulse allows formation of free or quasi-free electron pairs, e 2 - , which decay back into F centres on a time scale which is long compared with that for individual electrons. (author)

  18. Zinc-Containing Hydroxyapatite Enhances Cold-Light-Activated Tooth Bleaching Treatment In Vitro

    Science.gov (United States)

    Shi, Xinchang

    2017-01-01

    Cold-light bleaching treatment has grown to be a popular tooth whitening procedure in recent years, but its side effect of dental enamel demineralization is a widespread problem. The aim of this study was to synthesize zinc-substituted hydroxyapatite as an effective biomaterial to inhibit demineralization or increase remineralization. We synthesized zinc-substituted hydroxyapatite containing different zinc concentrations and analysed the product using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and energy dispersive spectrometer (EDS). The biological assessment of Zn-HA was conducted by CCK-8 assay and bacterial inhibition tests. pH cycling was performed to estimate the effect of Zn-HA on the enamel surface after cold-light bleaching treatment. The XRD, FTIR, and EDS results illustrated that zinc ions and hydroxyapatite combined in two forms: (1) Zn2+ absorbed on the surface of HA crystal and (2) Zn2+ incorporated into the lattice of HA. The results indicated that 2% Zn-HA, 4% Zn-HA, and 8% Zn-HA effectively inhibited the growth of bacteria yet showed poor biocompatibility, whereas 1% Zn-HA positively affected osteoblast proliferation. The XRD and scanning electron microscopy (SEM) results showed that the use of Zn-HA in pH cycling is obviously beneficial for enamel remineralization. Zinc-substituted hydroxyapatite could be a promising biomaterial for use in cold-light bleaching to prevent enamel demineralization. PMID:29159178

  19. Zinc-Containing Hydroxyapatite Enhances Cold-Light-Activated Tooth Bleaching Treatment In Vitro

    Directory of Open Access Journals (Sweden)

    Yi Li

    2017-01-01

    Full Text Available Cold-light bleaching treatment has grown to be a popular tooth whitening procedure in recent years, but its side effect of dental enamel demineralization is a widespread problem. The aim of this study was to synthesize zinc-substituted hydroxyapatite as an effective biomaterial to inhibit demineralization or increase remineralization. We synthesized zinc-substituted hydroxyapatite containing different zinc concentrations and analysed the product using X-ray diffraction (XRD, Fourier transform infrared (FTIR spectroscopy, and energy dispersive spectrometer (EDS. The biological assessment of Zn-HA was conducted by CCK-8 assay and bacterial inhibition tests. pH cycling was performed to estimate the effect of Zn-HA on the enamel surface after cold-light bleaching treatment. The XRD, FTIR, and EDS results illustrated that zinc ions and hydroxyapatite combined in two forms: (1 Zn2+ absorbed on the surface of HA crystal and (2 Zn2+ incorporated into the lattice of HA. The results indicated that 2% Zn-HA, 4% Zn-HA, and 8% Zn-HA effectively inhibited the growth of bacteria yet showed poor biocompatibility, whereas 1% Zn-HA positively affected osteoblast proliferation. The XRD and scanning electron microscopy (SEM results showed that the use of Zn-HA in pH cycling is obviously beneficial for enamel remineralization. Zinc-substituted hydroxyapatite could be a promising biomaterial for use in cold-light bleaching to prevent enamel demineralization.

  20. Bleaching and diffusion dynamics in optofluidic dye lasers

    DEFF Research Database (Denmark)

    Gersborg-Hansen, Morten; Balslev, Søren; Mortensen, Asger

    2007-01-01

    The authors have investigated the bleaching dynamics that occur in optofluidic dye lasers where the liquid laser dye in a microfluidic channel is locally bleached due to optical pumping. They find that for microfluidic devices, the dye bleaching may be compensated through diffusion of dye molecules...

  1. Bleaching of the thermoluminescence of feldspars by sunlight

    International Nuclear Information System (INIS)

    Robertson, G.B.; Prescott, J.R.; Hutton, J.T.

    1991-01-01

    Feldspars are an important component of materials used for thermoluminescence (TL) and photoluminescence (PL) dating of sediments; and successful dating implies a knowledge of the degree of re-setting by exposure to sunlight of the stored luminescence energy. We have studied the bleaching by full sunlight of the TL of six alkali feldspars of representative composition and of one oligoclase. The high potassium and high sodium feldspars are the brightest, and are also the least easily bleached, whereas those of intermediate (K-Na) composition bleach quickly. On a time scale of upwards of 16 h, all samples would have bleached enough for them to be useful for TL dating. A search was made for individual glow curve peaks that bleach particularly quickly (and are thus similar to the well-known 325 o C peak used in the TL dating of quartz). In the samples studied, there was only one glow curve peak that was selectively susceptible to bleaching: the 280 o C peak in oligoclase. (author)

  2. Thermoluminescence emission spectra and optical bleaching of oligoclase

    International Nuclear Information System (INIS)

    Bos, A.J.J.; Piters, T.M.; Ypma, P.J.

    1994-01-01

    Thermoluminescence (TL) spectra of oligoclase samples have been recorded in the temperature range from 300 to 700 K and the wavelength range from 300 to 850 nm. Like other feldspars, oligoclase produces blue (peaking at 460 nm) and red (peaking at 765 nm) emission bands. The maximum of the red emission occurs 20 K lower than that of the blue band. Optical bleaching was performed at wavelengths varying from 360 to 800 nm. Bleaching of artificially irradiated oligoclase causes a decrease of the TL signal. The bleaching efficiency increases with decreasing wavelength. Bleaching does not only influence the height of the glow curve but also the shape. An interesting observation is that the ratio of the blue and red band intensities is not affected by a bleaching procedure. No evidence has been found that bleaching influences the shape of the emission spectra. The correlation between the blue and red bands is discussed. (Author)

  3. Effect of laser-assisted bleaching with Nd:YAG and diode lasers on shear bond strength of orthodontic brackets.

    Science.gov (United States)

    Mirhashemi, Amirhossein; Emadian Razavi, Elham Sadat; Behboodi, Sara; Chiniforush, Nasim

    2015-12-01

    The aim of the present study was to assess the effect of laser-assisted bleaching with neodymium:yttrium-aluminum-garnet (Nd:YAG) and diode lasers on shear bond strength (SBS) of orthodontic brackets. One hundred and four extracted human premolars were randomly divided into four groups: group 1: No bleaching applied (control group); group 2: Teeth bleached with 40 % hydrogen peroxide; group 3: Teeth treated with 30 % hydrogen peroxide activated with Nd:YAG laser (1064 nm, 2.5 W, 25 Hz, pulse duration of 100 μs, 6 mm distance); and group 4: Teeth treated with 30 % hydrogen peroxide activated with diode laser (810 nm, 1 W, CW, 6 mm distance). Equal numbers of teeth in groups 2, 3, and 4 were bonded at start, 1 h, 24 h, and 1 week after bleaching. A universal testing machine measured the SBS of the samples 24 h after bonding. After bracket debonding, the amount of residual adhesive on the enamel surface was observed under a stereomicroscope to determine the adhesive remnant index (ARI) scores. The SBS in the unbleached group was significantly higher than that in the bleached groups bonded immediately and 1 h after laser-assisted bleaching (P laser-assisted bleaching, the SBS was found to be significantly lower than that in the control group. Significant differences in the ARI scores existed among groups as well. The SBS of brackets seems to increase quickly within an hour after laser-assisted bleaching and 24 h after conventional bleaching. Thus, this protocol can be recommended if it is necessary to bond the brackets on the same day of bleaching.

  4. A new, high-resolution global mass coral bleaching database.

    Directory of Open Access Journals (Sweden)

    Simon D Donner

    Full Text Available Episodes of mass coral bleaching have been reported in recent decades and have raised concerns about the future of coral reefs on a warming planet. Despite the efforts to enhance and coordinate coral reef monitoring within and across countries, our knowledge of the geographic extent of mass coral bleaching over the past few decades is incomplete. Existing databases, like ReefBase, are limited by the voluntary nature of contributions, geographical biases in data collection, and the variations in the spatial scale of bleaching reports. In this study, we have developed the first-ever gridded, global-scale historical coral bleaching database. First, we conducted a targeted search for bleaching reports not included in ReefBase by personally contacting scientists and divers conducting monitoring in under-reported locations and by extracting data from the literature. This search increased the number of observed bleaching reports by 79%, from 4146 to 7429. Second, we employed spatial interpolation techniques to develop annual 0.04° × 0.04° latitude-longitude global maps of the probability that bleaching occurred for 1985 through 2010. Initial results indicate that the area of coral reefs with a more likely than not (>50% or likely (>66% probability of bleaching was eight times higher in the second half of the assessed time period, after the 1997/1998 El Niño. The results also indicate that annual maximum Degree Heating Weeks, a measure of thermal stress, for coral reefs with a high probability of bleaching increased over time. The database will help the scientific community more accurately assess the change in the frequency of mass coral bleaching events, validate methods of predicting mass coral bleaching, and test whether coral reefs are adjusting to rising ocean temperatures.

  5. A new, high-resolution global mass coral bleaching database.

    Science.gov (United States)

    Donner, Simon D; Rickbeil, Gregory J M; Heron, Scott F

    2017-01-01

    Episodes of mass coral bleaching have been reported in recent decades and have raised concerns about the future of coral reefs on a warming planet. Despite the efforts to enhance and coordinate coral reef monitoring within and across countries, our knowledge of the geographic extent of mass coral bleaching over the past few decades is incomplete. Existing databases, like ReefBase, are limited by the voluntary nature of contributions, geographical biases in data collection, and the variations in the spatial scale of bleaching reports. In this study, we have developed the first-ever gridded, global-scale historical coral bleaching database. First, we conducted a targeted search for bleaching reports not included in ReefBase by personally contacting scientists and divers conducting monitoring in under-reported locations and by extracting data from the literature. This search increased the number of observed bleaching reports by 79%, from 4146 to 7429. Second, we employed spatial interpolation techniques to develop annual 0.04° × 0.04° latitude-longitude global maps of the probability that bleaching occurred for 1985 through 2010. Initial results indicate that the area of coral reefs with a more likely than not (>50%) or likely (>66%) probability of bleaching was eight times higher in the second half of the assessed time period, after the 1997/1998 El Niño. The results also indicate that annual maximum Degree Heating Weeks, a measure of thermal stress, for coral reefs with a high probability of bleaching increased over time. The database will help the scientific community more accurately assess the change in the frequency of mass coral bleaching events, validate methods of predicting mass coral bleaching, and test whether coral reefs are adjusting to rising ocean temperatures.

  6. Coral bleaching--capacity for acclimatization and adaptation.

    Science.gov (United States)

    Coles, S L; Brown, Barbara E

    2003-01-01

    Coral bleaching, i.e., loss of most of the symbiotic zooxanthellae normally found within coral tissue, has occurred with increasing frequency on coral reefs throughout the world in the last 20 years, mostly during periods of El Nino Southern Oscillation (ENSO). Experiments and observations indicate that coral bleaching results primarily from elevated seawater temperatures under high light conditions, which increases rates of biochemical reactions associated with zooxanthellar photosynthesis, producing toxic forms of oxygen that interfere with cellular processes. Published projections of a baseline of increasing ocean temperature resulting from global warming have suggested that annual temperature maxima within 30 years may be at levels that will cause frequent coral bleaching and widespread mortality leading to decline of corals as dominant organisms on reefs. However, these projections have not considered the high variability in bleaching response that occurs among corals both within and among species. There is information that corals and their symbionts may be capable of acclimatization and selective adaptation to elevated temperatures that have already resulted in bleaching resistant coral populations, both locally and regionally, in various areas of the world. There are possible mechanisms that might provide resistance and protection to increased temperature and light. These include inducible heat shock proteins that act in refolding denatured cellular and structural proteins, production of oxidative enzymes that inactivate harmful oxygen radicals, fluorescent coral pigments that both reflect and dissipate light energy, and phenotypic adaptations of zooxanthellae and adaptive shifts in their populations at higher temperatures. Such mechanisms, when considered in conjunction with experimental and observational evidence for coral recovery in areas that have undergone coral bleaching, suggest an as yet undefined capacity in corals and zooxanthellae to adapt to

  7. Analysis of waste management issues arising from a field study evaluating decontamination of a biological agent from a building.

    Science.gov (United States)

    Lemieux, P; Wood, J; Drake, J; Minamyer, S; Silvestri, E; Yund, C; Nichols, T; Ierardi, M; Amidan, B

    2016-01-01

    The Bio-response Operational Testing and Evaluation (BOTE) Project was a cross-government effort designed to operationally test and evaluate a response to a biological incident (release of Bacillus anthracis [Ba] spores, the causative agent for anthrax) from initial public health and law enforcement response through environmental remediation. The BOTE Project was designed to address site remediation after the release of a Ba simulant, Bacillus atrophaeus spp. globigii (Bg), within a facility, drawing upon recent advances in the biological sampling and decontamination areas. A key component of response to a biological contamination incident is the proper management of wastes and residues, which is woven throughout all response activities. Waste is generated throughout the response and includes items like sampling media packaging materials, discarded personal protective equipment, items removed from the facility either prior to or following decontamination, aqueous waste streams, and materials generated through the application of decontamination technologies. The amount of residual contaminating agent will impact the available disposal pathways and waste management costs. Waste management is an integral part of the decontamination process and should be included through "Pre-Incident" response planning. Overall, the pH-adjusted bleach decontamination process generated the most waste from the decontamination efforts, and fumigation with chlorine dioxide generated the least waste. A majority of the solid waste generated during pH-adjusted bleach decontamination was the nonporous surfaces that were removed, bagged, decontaminated ex situ, and treated as waste. The waste during the two fumigation rounds of the BOTE Project was associated mainly with sampling activities. Waste management activities may represent a significant contribution to the overall cost of the response/recovery operation. This paper addresses the waste management activities for the BOTE field test

  8. Spectrophotometric assessment of tooth bleaching under orthodontic braquets bonded with different materials

    Directory of Open Access Journals (Sweden)

    Camila Maria Lima de CASTRO

    2017-10-01

    Full Text Available Abstract Introduction patients have been submitted to tooth bleaching during orthodontic treatment for aesthetic purposes or to anticipate the replacement of restorations after completion of the treatment. Objective to evaluate the effectiveness of tooth bleaching under orthodontic brackets bonded with different materials. Material and method a hundred bovine enamel blocks were divided into two groups, at-home and in-office tooth bleaching. In-office bleaching was subdivided into five groups (n = 10: HP (control - without brackets; SA(t - brackets bonded with Transbond XT, without bleaching; SA(fm - brackets bonded with Orthodontic Fill Magic, without bleaching; HP(t - brackets bonded with Transbond XT subjected to bleaching; and HP(fm - brackets bonded with Orthodontic Fill Magic subjected to bleaching. At-home bleaching followed the same treatments, only replacing the bleaching agent. Spectrophotometric assessment was used for tooth color determination at three moments: 1 before staining (baseline; 2 after staining; 3 after bonding the brackets and bleaching procedures. Data were submitted to ANOVA and analyzed by Tukey's test (p < 0.05. Result For both types of bleaching, the control group had an effective bleaching action. Groups using Transbond XT presented greater bleaching potential among the groups with orthodontic accessory, but the bleaching action differed from the positive control. Groups using Orthodontic Fill Magic presented no bleaching action, resembling the negative control groups (artificial saliva. Conclusion the orthodontic bracket impaired the effectiveness of the at-home and in-office bleaching treatment, regardless of the resin used for bonding.

  9. A bleaching earth from egyptian local deposits

    Directory of Open Access Journals (Sweden)

    El Kinawy, Omayma S.

    2001-10-01

    Full Text Available The present investigation deals with the bleaching of vegetable oils using activated clays collected from some deposits in Egypt as compared to Tonsil FF currently used by local oil industry. The comparison was made; not only on the basis of the decolourising power of the earth, but also on the basis of its effects on the oil acidity, formation of the oil peroxides and the decomposition rate of the formed peroxides to aldehydes and ketones during the bleaching process. The activation of the collected earth samples was made using 4N HCl, 6N HCl and 30 % H2SO4. The bleaching tests of the activated samples were performed using the major four oil types processed in Egypt being cottonseed, sunflower, soybean and palm oils. In addition to the laboratory-evaluation tests, the performance of the activated samples, which showed promise on the lab-scale have been also tested on an industrial scale. The industrial application has proved that the activated local earth's can be successfully used as bleaching earth of local oils. Thus it can be used as a substitute of the varieties currently imported and used by the local oil sector.La presente investigación trata de la decoloración de aceites vegetales usando tierras activadas obtenidas de yacimientos egipcios, comparándola con el Tonsil FF usado normalmente en la industria oleícola local. La comparación se realizó, no sólo sobre la base del poder decolorante de la tierra, sino también sobre la base de sus efectos en la acidez del aceite, la formación de peróxidos y la velocidad de descomposición de los peróxidos formados en aldehidos y cetonas durante el proceso de decoloración. La activación de las muestras de tierras recogidas se hizo utilizando ClH 4N, ClH 6N y H2SO4 30 %. Los tests de decoloración de las muestras activadas se llevaron a cabo usando los cuatro tipos mayoritarios de aceites procesados en Egipto: aceite de semilla de algodón, de girasol, de soja y de palma. Además de los

  10. Effects of bleaching wastewater irrigation on soil quality of constructed reed wetlands

    Directory of Open Access Journals (Sweden)

    Cheng Ding

    2016-10-01

    Full Text Available Constructed reed wetland microcosms (CRWs in a lab of east China have been irrigated with bleaching wastewater per month for a reed growth season. The soil physicochemical properties, enzyme activities (i.e. urease, invertase, polyphenol oxidase, alkaline phosphatase and cellulase and soil microbial diversity were assayed before and after the exposure experiment. Compared to the river water irrigated controls (CKs, bleaching wastewater application has no marked influence on soil pH, but significantly increased soil Na+, total halogen and absorbable organic halogen (AOX contents, which induced the increasing of soil electrical conductivity. Furthermore, soil enzyme activities displayed significant variation (except for polyphenol oxidase. Bleaching wastewater irrigation decreased Sorenson’s pairwise similarity coefficient (Cs, which indicated the changes of the structure of bacterial and fungal communities. However, only the diversity of bacterial community was inhibited and has no effect on the diversity of fungal community, as evidenced by the calculated Shannon–Wiener index (H.

  11. Thermographic and spectrophotometric analysis of the extrinsic tooth bleaching using a diode laser and a LED system. In vitro

    International Nuclear Information System (INIS)

    Micheli, Paola Racy de

    2004-01-01

    The aim of this study was to evaluate the intra-pulpal temperature change, as well as to compare the bleaching power of a 38% hydrogen peroxide (Opalescence Xtra Boost- Ultradent. Inc), when activated with a diode laser, with a LED system and without activation, in the extrinsic tooth bleaching in vitro. Ten mandibular human incisors, a thermocouple, 45 bovine incisors and a spectrophotometer (Shade Eye- Shofu) for the color analysis. The samples were divided into 3 groups: 38% hydrogen peroxide activated by a diode laser (ZAP lasers, wavelength 808 nm ± 5, power of 1,4 W); 38% hydrogen peroxide activated by LED (Bright LEC-Mmoptics, wavelength 470 nm ± 25, power of 380 mW); 38% hydrogen peroxide without activation. After the artificial pigmentation, the bleaching agent acted for the same time in the 3 groups, differing only by the type of activation. The results of temperature showed that the LED activation was safer than the diode laser, which, in some measures exceeded the limit of 5.6 deg C. The luminosity of the samples did not show significantly statistics differences in none of the groups and moments of this study. The diode laser and LED activation did not influenced at the bleaching power of the peroxide, which showed effective for removing stains, with great capacity of bleaching bovine tooth artificially darkened. (author)

  12. Changes in coral-associated microbial communities during a bleaching event.

    Science.gov (United States)

    Bourne, David; Iida, Yuki; Uthicke, Sven; Smith-Keune, Carolyn

    2008-04-01

    Environmental stressors such as increased sea surface temperatures are well-known for contributing to coral bleaching; however, the effect of increased temperatures and subsequent bleaching on coral-associated microbial communities is poorly understood. Colonies of the hard coral Acropora millepora were tagged on a reef flat off Magnetic Island (Great Barrier Reef) and surveyed over 2.5 years, which included a severe bleaching event in January/February 2002. Daily average water temperatures exceeded the previous 10-year average by more than 1 degrees C for extended periods with field-based visual surveys recording all tagged colonies displaying signs of bleaching. During the bleaching period, direct counts of coral zooxanthellae densities decreased by approximately 64%, before recovery to pre-bleaching levels after the thermal stress event. A subset of three tagged coral colonies were sampled through the bleaching event and changes in the microbial community elucidated. Denaturing gradient gel electrophoresis (DGGE) analysis demonstrated conserved bacterial banding profiles between the three coral colonies, confirming previous studies highlighting specific microbial associations. As coral colonies bleached, the microbial community shifted and redundancy analysis (RDA) of DGGE banding patterns revealed a correlation of increasing temperature with the appearance of Vibrio-affiliated sequences. Interestingly, this shift to a Vibrio-dominated community commenced prior to visual signs of bleaching. Clone libraries hybridized with Vibrio-specific oligonucleotide probes confirmed an increase in the fraction of Vibrio-affiliated clones during the bleaching period. Post bleaching, the coral microbial associations again shifted, returning to a profile similar to the fingerprints prior to bleaching. This provided further evidence for corals selecting and shaping their microbial partners. For non-bleached samples, a close association with Spongiobacter-related sequences were

  13. Coral mass bleaching and reef temperatures at Navassa Island, 2006

    Science.gov (United States)

    Miller, M. W.; Piniak, G. A.; Williams, D. E.

    2011-01-01

    Bleaching and associated mortality is an extreme threat to the persistence of coral populations in the projected warming regime of the next few decades. Recent evidence indicates that thermal bleaching thresholds may be affected by water quality gradients. The unexpected encounter of a coral mass bleaching event at a remote, uninhabited Caribbean island (Navassa) during a routine reef assessment cruise in November 2006 provided the opportunity to characterize bleaching responses and thermal exposure in an oceanic area with negligible continental influence or human impact on water quality. The coral taxa most susceptible to bleaching were Agaricia spp. and Montastraea faveolata. Siderastraea siderea, Diploria spp. and Porites porites were intermediately affected, while Porites astreoides and Montastraea cavernosa were minimally affected and negligible bleaching was observed in Acropora palmata. Bleaching prevalence (colonies > 4 cm diameter) ranged from 0.16 to 0.63 among sites. Deeper sites (between 18 and 37 m) had significantly higher prevalence of bleaching than shallow sites (<10 m). This general pattern of more bleaching in deeper sites also occurred within species. Though exposure to high-temperature stress was not greater at deeper sites, water motion, which may bolster bleaching resistance, was likely less. In situ loggers indicated temperatures over 30 °C initiated at shallow sites in mid-August, at deeper sites in early September, and were persistent at all sites until mid-October. Long term (1983-2007) climatologies constructed from AVHRR SSTs suggest that the mass bleaching event observed at Navassa in 2006 corresponded with greater intensity and duration of warm temperature anomalies than occurred in 2005, for which no in situ observations (bleaching nor temperature) are available.

  14. Coral community response to bleaching on a highly disturbed reef.

    Science.gov (United States)

    Guest, J R; Low, J; Tun, K; Wilson, B; Ng, C; Raingeard, D; Ulstrup, K E; Tanzil, J T I; Todd, P A; Toh, T C; McDougald, D; Chou, L M; Steinberg, P D

    2016-02-15

    While many studies of coral bleaching report on broad, regional scale responses, fewer examine variation in susceptibility among coral taxa and changes in community structure, before, during and after bleaching on individual reefs. Here we report in detail on the response to bleaching by a coral community on a highly disturbed reef site south of mainland Singapore before, during and after a major thermal anomaly in 2010. To estimate the capacity for resistance to thermal stress, we report on: a) overall bleaching severity during and after the event, b) differences in bleaching susceptibility among taxa during the event, and c) changes in coral community structure one year before and after bleaching. Approximately two thirds of colonies bleached, however, post-bleaching recovery was quite rapid and, importantly, coral taxa that are usually highly susceptible were relatively unaffected. Although total coral cover declined, there was no significant change in coral taxonomic community structure before and after bleaching. Several factors may have contributed to the overall high resistance of corals at this site including Symbiodinium affiliation, turbidity and heterotrophy. Our results suggest that, despite experiencing chronic anthropogenic disturbances, turbid shallow reef communities may be remarkably resilient to acute thermal stress.

  15. Kraft pulp bleaching with molybdenum activated acid peroxide (P{sub Mo} stage); Branqueamento de polpa celulosica kraft de eucalipto com peroxido acido ativado por molibdenio

    Energy Technology Data Exchange (ETDEWEB)

    Rabelo, Marcos Sousa [Servico Nacional de Aprendizagem Industrial (SENAI), Lauro de Freitas, BA (Brazil). Dept. Regional da Bahia; Silva, Vanessa Lopes; Barros, Denise Pires de; Colodette, Jorge Luiz [Universidade Federal de Vicosa (UFV), MG (Brazil). Dept. de Engenharia Florestal; Sacon, Vera Maria; Silva, Marcelo Rodrigues da [Votorantim Celulose e Papel, Jacarei, SP (Brazil)

    2009-07-01

    Optimum conditions to run the P{sub Mo} stage for bleaching eucalyptus kraft pulp were 90 deg C, pH 3.5, 2 h, 0.1 kg/t Mo and 5 kg/t H{sub 2}O{sub 2}. The P{sub Mo} stage efficiency increased with decreasing pH (1.5-5.5) and increasing temperature (75-90 deg C), time (2-4 h), and hydrogen peroxide (3-10 kg/t) and molybdenum concentration (0.1-0.4 kg/t). The implementation of the P{sub Mo} stage, as replacement for the A stage, decreased total active chlorine demand of the OAZDP sequence by 6 kg/t to reach 90% ISO, both in laboratory and mill scale. Such practice resulted in decreased bleaching chemical costs to produce fully bleached pulp of 90% ISO. (author)

  16. HYDROGEN PEROXIDE BLEACHING OF CMP PULP USING MAGNESIUM HYDROXIDE

    Directory of Open Access Journals (Sweden)

    Farhad Zeinaly

    2009-11-01

    Full Text Available Conventional bleaching of hardwood CMP pulp with magnesium hydroxide (Mg(OH2 show significant benefits over bleaching with sodium hydroxide (NaOH under various conditions. Magnesium hydroxide bleaching generate higher optical properties, higher pulp yield and lower effluent COD at the same chemical charge, but the physical properties were found to be similar for both processes. The initial freeness of the bleached pulps and refining value to reach a target freeness (about 350 ml. CSF were more for the Mg(OH2-based process. The residual peroxide of filtrate from the Mg(OH2-based process was very high as compared to conventional bleaching.

  17. Optimization of Dithionite Bleaching of High Yield Bagasse Pulp

    International Nuclear Information System (INIS)

    Mohamed, E.

    2005-01-01

    High yield bagasse pulp was prepared by soaking bagasse in 10 % cold sodium hydroxide for 24 hours and then refluxing for two hours at 95 degree C. Optimization of dithionite bleaching was attained by investigation of different parameters as consistency, temperature, time and ph. Effect of additives as chelating agent (EDTA) or stabilizing of bleaching solution (Zn compound and hexamethylene tetramine) was considered. The effect of air content was also studied. One and two stages bleaching of the pulp were investigated by using sodium dithionite (D) as a sole bleaching agent or after application of one stage bleaching by hydrogen peroxide to attain high brightness for high yield pulp

  18. Effect of coffe and a cola-based soft drink on the color stability of bleached bovine incisors considering the time elapsed after bleaching

    Directory of Open Access Journals (Sweden)

    Rodrigo PIROLO

    2014-12-01

    Full Text Available There is no consensus about the waiting time necessary for the patient to start consuming beverages containing colorants again after bleaching. Objective: To evaluate the influence of beverages with coloring agents on bleached bovine incisors considering the time elapsed after bleaching. Materials and methods: Sixty bovine incisors were bleached with 35% hydrogen peroxide for in-office use (Whiteness HP Max and divided into 10 groups. The color was evaluated with a spectrophotometer (Spectro Shade MICRO before and after bleaching, employing the CIE-Lab system. After bleaching, the teeth were exposed for 5 min to coffee or cola-based soft drink (CBSD at different periods after bleaching: 10 min, 1 h, 24 h, 48 h, and 72 h. Color (∆E and lightness (∆L variations were obtained from the CIE-Lab coordinates. Data were subjected to two-way ANOVA and Tukey HSD tests (p<0.05. Results: Significant differences were observed between groups for both the ∆L and ∆E values (p<0.001. All specimens presented a decrease in brightness (negative ∆L. The highest ∆E values were observed for teeth stained with a CBSD at 10 min and 1 h (4.12 and 4.16, respectively. Teeth pigmented with coffee presented ∆E values below 3.3 units for all evaluation times. Conclusion: The exposure to coffee after bleaching causes less color changes than the exposure to a CBSD regardless of the time after bleaching.

  19. In situ observations of coral bleaching in the central Saudi Arabian Red Sea during the 2015/2016 global coral bleaching event.

    Science.gov (United States)

    Monroe, Alison A; Ziegler, Maren; Roik, Anna; Röthig, Till; Hardenstine, Royale S; Emms, Madeleine A; Jensen, Thor; Voolstra, Christian R; Berumen, Michael L

    2018-01-01

    Coral bleaching continues to be one of the most devastating and immediate impacts of climate change on coral reef ecosystems worldwide. In 2015, a major bleaching event was declared as the "3rd global coral bleaching event" by the United States National Oceanic and Atmospheric Administration, impacting a large number of reefs in every major ocean. The Red Sea was no exception, and we present herein in situ observations of the status of coral reefs in the central Saudi Arabian Red Sea from September 2015, following extended periods of high temperatures reaching upwards of 32.5°C in our study area. We examined eleven reefs using line-intercept transects at three different depths, including all reefs that were surveyed during a previous bleaching event in 2010. Bleaching was most prevalent on inshore reefs (55.6% ± 14.6% of live coral cover exhibited bleaching) and on shallower transects (41% ± 10.2% of live corals surveyed at 5m depth) within reefs. Similar taxonomic groups (e.g., Agariciidae) were affected in 2015 and in 2010. Most interestingly, Acropora and Porites had similar bleaching rates (~30% each) and similar relative coral cover (~7% each) across all reefs in 2015. Coral genera with the highest levels of bleaching (>60%) were also among the rarest (coral cover) in 2015. While this bodes well for the relative retention of coral cover, it may ultimately lead to decreased species richness, often considered an important component of a healthy coral reef. The resultant long-term changes in these coral reef communities remain to be seen.

  20. Temperament and perception of tooth bleaching results

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    Katarzyna Mehr

    2016-09-01

    Full Text Available Background . The neurophysiological process of perceiving the results of tooth bleaching requires the correct interaction between the central nervous system and the organs of sight. Exaggerated beliefs concerning defective facial features may enhance inner attitudes about one’s own color of dentition, as well as a feeling of dissatisfaction with the degree of leaching. Objectives. The study aimed to assess the degree of the patient satisfaction with the results of tooth bleaching in relation to their temperament. Material and methods. There were 68 generally healthy volunteers, aged 28–38 years, with external discolorations of the teeth. They had never undergone dental bleaching and their frontal teeth did not have any fillings. After clinical evaluation and the completion of formalities, the patients were asked to fill in Strelau’s temperament questionnaire. Questionnaires and visual status were assessed three times by three doctors: before bleaching, and then 24 hours and two weeks after the home-bleaching operation, which was done with the use of Opalescence (Ultradent in uniform sequence. Results . There were practically no adverse side results, except a periodic dentin hypersensitivity that occurred periodically in 44 patients. The results of the visual assessment performed by the physicians did not differ. The questionnaire data showed that women were more critical of the results in relation to the expectations. Among elancholics, full satisfaction was declared by 41%, whereas among sanguine people, full satisfaction was obtained by 85%. Satisfaction with the aesthetic results was associated with bleaching by at least 4 degrees. Conclusions . Patients’ temperament affects their subjective evaluation of the effectiveness of tooth bleaching, which should be taken into consideration in the patient’s individual dental treatment plan.

  1. The effect of baking soda when applied to bleached enamel prior to restorative treatment.

    Science.gov (United States)

    Tostes, Bhenya Ottoni; Mondelli, Rafael Francisco Lia; Lima-Arsati, Ynara Bosco de Oliveira; Rodrigues, Jose Augusto; Costa, Leonardo Cesar

    2013-08-01

    This in vitro study evaluated the effect of 10% baking soda solution and sodium bicarbonate powder (applied with jets) when applied to bleached enamel prior to restorative treatment. The surfaces of 40 bovine incisors were flattened and divided into 5 groups (n = 8): Group B (bleached and restored, negative control), Group W (bleached, stored in distilled water for 7 days, and restored), Group BSJ (bleached, abraded with baking soda jet for 1 min, and restored), Group BSS (bleached, application of 10% baking soda solution for 5 min, and restored), and Group R (restored, without bleaching, positive control). The samples were bleached in 1 session with 3 applications of 35% HP-based gel and activated with a LED appliance for 9 min each. Resin composite cylinders (2 mm height and 0.8 mm diameter) were made on the enamel surface after the acid etching and a conventional 1-step single vial adhesive application was performed. After storage in distilled water (37 ± 1°C, 24 hr), the microshear bond test was performed (1 mm/min). ANOVA and Tukey tests were applied to compare the results. The mean results of these tests showed that Groups W, BBS, and R were not statistically different. These groups also indicated a higher bond strength when compared with Groups B and BSJ. The application of 10% baking soda solution for 5 min may be an alternative pre-restorative treatment for bleached enamel, but further studies are needed to consider whether or not this treatment may be effectively used in clinical practice.

  2. The effects of habitat on coral bleaching responses in Kenya.

    Science.gov (United States)

    Grimsditch, Gabriel; Mwaura, Jelvas M; Kilonzo, Joseph; Amiyo, Nassir

    2010-06-01

    This study examines the bleaching responses of scleractinian corals at four sites in Kenya (Kanamai, Vipingo, Mombasa and Nyali) representing two distinct lagoon habitats (relatively shallow and relatively deep). Bleaching incidence was monitored for the whole coral community, while zooxanthellae densities and chlorophyll levels were monitored for target species (Pocillopora damicornis, Porites lutea, and Porites cylindrica) during a non-bleaching year (2006) and a year of mild-bleaching (2007). Differences in bleaching responses between habitats were observed, with shallower sites Kanamai and Vipingo exhibiting lower bleaching incidence than deeper sites Nyali and Mombasa. These shallower lagoons display more fluctuating thermal and light environments than the deeper sites, suggesting that corals in the shallower lagoons have acclimatized and/or adapted to the fluctuating environmental conditions they endure on a daily basis and have become more resistant to bleaching stress. In deeper sites that did exhibit higher bleaching (Mombasa and Nyali), it was found that coral recovery occurred more quickly in the protected area than in the non-protected area.

  3. Clinical Evaluation of Genotoxicity of In-office Bleaching.

    Science.gov (United States)

    Rezende, M; De Geus, J L; Loguercio, A D; Reis, A; Kossatz, D

    The aim of this study was to evaluate the genotoxicity of in-office bleaching with 35% hydrogen peroxide in epithelial cells from the gingival and lip tissues. Thirty volunteers with central incisors shade A1 or darker were selected for this study. The gingival tissue of the teeth to be bleached was isolated with a light-polymerized resin dam, and the 35% hydrogen peroxide gel was administered during three 15-minute applications over the course of the 45-minute application period. Two bleaching sessions with a one-week interval in between were performed. Exfoliated oral mucosa gingival epithelial cells and upper lip lining were collected at baseline and one month after the in-office dental bleaching. The scraped cells were placed on clean glass slides and smears were prepared. After staining with Giemsa solution, two blinded examiners performed cell and micronuclei counts under a 100× optical microscope. Tooth sensitivity was evaluated using the Visual Analogue Scale (VAS). Shade evaluation was recorded before and one month after the bleaching treatment with the value-oriented shade guide Vita Bleachedguide 3D-MASTER and the spectrophotometer Vita Easyshade. Data from the shade guide units and the micronuclei (MN) frequency were subjected to a Mann-Whitney test (α=0.05). The overall difference between before and one month after the bleaching treatment (ΔE and ΔSGU), absolute risk, and intensity of tooth sensitivity (TS) were calculated, as was the 95% confidence interval (CI). The frequency of MN was not increased after bleaching with 35% hydrogen peroxide in both study groups (p>0.05). The absolute risk of TS of the participants was 93% (95% CI, 79%-98%), with a mean VAS intensity of 5.7 ± 2.9 (95% CI, 4.6-6.8). Meaningful whitening was observed after bleaching. The change in shade guide units in the Bleachedguide 3D-MASTER was 2.3 ± 1.4. In terms of ΔE, the change in color was 7.7 ± 3.5. The in-office bleaching did not induce DNA damage to the gingival

  4. Laser and thermal bleaching of colour centres in sodium borate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Bukharaev, A A; Yafaev, N R [AN SSSR, Kazan. Fiziko-Tekhnicheskij Inst.

    1978-12-01

    The maximum of the additional absorption band in ..gamma..- or UV-irradiated sodium borate glasses shifts to higher energy when the low-energy side of the band is bleached by a helium-neon laser, ..lambda.. = 632.8 nm. Simultaneously the half-width of the additional absorption band decreases. This phenomenon is associated with the fact that because of structural disorder of glasses there is a distribution of ground-state energies of trapped electrons forming the light-sensitive absorption band. The distribution interval of the activation energy for trapped electrons is estimated using the decomposition of the initial thermal bleaching curves into components. For UV irradiated glasses it is aproximately 0.24 eV, and for ..gamma..-irradiated glasses only 0.12 eV. These values correlate with the relative shift maximum of the absorption band at laser bleaching.

  5. In vitro Assessment of Influence of Various Bleaching Protocols on the Strength of Ceramic Orthodontic Brackets bonded to Bleached Tooth Surface: A Comparative Study.

    Science.gov (United States)

    Iska, Divya; Devanna, Raghu; Singh, Madhvi; Chitumalla, Rajkiran; Balasubramanian, Sai C Bala; Goutam, Manish

    2017-12-01

    Esthetics is one of the common issues because of which patients consult dental orthodontic treatment. Two ways of tooth bleaching are available these days, which includes in-office bleach and home bleach. Various bleaching protocols are available these days for treating the tooth surfaces. Hence, we planned the present study for investigating the impact of various intracoronal bleaching protocols on shear bond strength of ceramic brackets bonded to tooth surface after bleaching. The present study included assessment of 100 extracted maxillary central incisors with the integrated buccal surface. A resin block was made and individual teeth were embedded in each block. Root canal therapy procedure was performed in all the teeth, after which 2 mm short of tooth apex up to the level of cementoenamel junction, removal of the root canal filling was done. All the samples were broadly divided into four study groups with 25 samples in each group. Bleaching procedure was carried in all the samples intracoronally followed by testing of shear bond strength using universal force testing machine. Following the modified adhesive remnant index (AI), assessment of remaining adhesive on the brackets was done. All the results were compiled and analyzed by Statistical Package for the Social Sciences (SPSS) software version 17.0. In the control group, mean shear bond strength was found to be 17.9 MPa. While comparing the carbamide peroxide (CP) group with sodium perborate study group, we observed a statistically significant difference. Nonsignificant results were obtained while comparing the shear bond strength in between sodium perborate group and hydrogen peroxide (HP) group. Intracoronal bleaching does affect the shear bond strength of ceramic brackets. Sodium perborate bleaching influences shear bond strength more strongly than other bleaching agents such as CP and HP. In patients undergoing orthodontic treatment, HP is a preferred agent where bleaching has to be followed by

  6. Kinetics and thermodynamics of aqueous Cu(II adsorption on heat regenerated spent bleaching earth

    Directory of Open Access Journals (Sweden)

    Enos W. Wambu

    2011-08-01

    Full Text Available This study investigated the kinetics and thermodynamics of copper(II removal from aqueous solutions using spent bleaching earth (SBE. The spent bleaching earth, a waste material from edible oil processing industries, was reactivated by heat treatment at 370 oC after residual oil extraction in excess methyl-ethyl ketone. Copper adsorption tests were carried out at room temperature (22±3 oC using 5.4 x 10-3C M metal concentrations. More than 70% metal removal was recorded in the first four hours although adsorption continued to rise to within 90% at 42 hours. The pH, adsorbent dosage and initial concentrations were master variables affecting RSBE adsorption of Cu(II ions. The adsorption equilibrium was adequately described by the Dubinin-Radushkevich (D-R and the Temkin isotherms and the maximum sorption capacity derived from the D-R isotherm was compared with those of some other low cost adsorbents. The adsorption process was found to follow Lagergren Pseudo-second order kinetics complimented by intra-particle diffusion kinetics at prolonged periods of equilibration. Based on the D-R isotherm adsorption energy and the thermodynamic adsorption free energy ∆G, it was suggested that the process is spontaneous and based on electrostatic interactions between the metal ions and exposed active sites in the adsorbent surface.

  7. Optical Emission Spectroscopy of an Atmospheric Pressure Plasma Jet During Tooth Bleaching Gel Treatment.

    Science.gov (United States)

    Šantak, Vedran; Zaplotnik, Rok; Tarle, Zrinka; Milošević, Slobodan

    2015-11-01

    Optical emission spectroscopy was performed during atmospheric pressure plasma needle helium jet treatment of various tooth-bleaching gels. When the gel sample was inserted under the plasma plume, the intensity of all the spectral features increased approximately two times near the plasma needle tip and up to two orders of magnitude near the sample surface. The color change of the hydroxylapatite pastille treated with bleaching gels in conjunction with the atmospheric pressure plasma jet was found to be in correlation with the intensity of OH emission band (309 nm). Using argon as an additive to helium flow (2 L/min), a linear increase (up to four times) of OH intensity and, consequently, whitening (up to 10%) of the pastilles was achieved. An atmospheric pressure plasma jet activates bleaching gel, accelerates OH production, and accelerates tooth bleaching (up to six times faster).

  8. Enzymes improve ECF bleaching of pulp

    Directory of Open Access Journals (Sweden)

    Lachenal, D.

    2006-07-01

    Full Text Available The delignification efficiency of different laccase enzymes was examined on the eucalyptus Kraft pulp. The laccase enzyme from Trametes versicolor showing the highest delignification efficiency was selected and used in the elemental chlorine-free bleaching sequence for improving the pulp bleachability. An appreciable reduction in chlorine dioxide consumption was also obtained. Further reduction in chlorine dioxide consumption was obtained when the same laccase treated pulp was subjected to an acid treatment after the extraction stage followed by the DEPD sequence. Elemental-chlorine free bleaching was also performed using the xylanase-laccase treated pulp. Xylanase treatment was incorporated to the laccase mediator system in the elemental-chlorine free bleaching both sequentially and simultaneously. The bleaching sequence DEPD followed and in both the cases, the reduction in chlorine dioxide consumption was greater in comparison to the control. The chlorine dioxide consumption was reduced further when xylanase-laccase treated pulp was given an additional acid treatment. The final pulp properties of the treated pulps were comparable to the control pulp.

  9. Annual coral bleaching and the long-term recovery capacity of coral

    Science.gov (United States)

    Schoepf, Verena; Grottoli, Andréa G.; Levas, Stephen J.; Aschaffenburg, Matthew D.; Baumann, Justin H.; Matsui, Yohei; Warner, Mark E.

    2015-01-01

    Mass bleaching events are predicted to occur annually later this century. Nevertheless, it remains unknown whether corals will be able to recover between annual bleaching events. Using a combined tank and field experiment, we simulated annual bleaching by exposing three Caribbean coral species (Porites divaricata, Porites astreoides and Orbicella faveolata) to elevated temperatures for 2.5 weeks in 2 consecutive years. The impact of annual bleaching stress on chlorophyll a, energy reserves, calcification, and tissue C and N isotopes was assessed immediately after the second bleaching and after both short- and long-term recovery on the reef (1.5 and 11 months, respectively). While P. divaricata and O. faveolata were able to recover from repeat bleaching within 1 year, P. astreoides experienced cumulative damage that prevented full recovery within this time frame, suggesting that repeat bleaching had diminished its recovery capacity. Specifically, P. astreoides was not able to recover protein and carbohydrate concentrations. As energy reserves promote bleaching resistance, failure to recover from annual bleaching within 1 year will likely result in the future demise of heat-sensitive coral species. PMID:26582020

  10. Coral Bleaching and Associated Mortality at Mayotte, Western Indian ...

    African Journals Online (AJOL)

    Mamoudzou 97600, Mayotte. Keywords: coral, bleaching, mortality, Mayotte, Western Indian Ocean. Abstract—Bleaching and associated coral mortality were assessed on fringing and barrier reefs on the north and east coasts of Mayotte from 1-24 May 2010. Major bleaching was encountered; nearly 80% of the corals were ...

  11. Natural Zeolite Sample and Investigation Its Use in Oil Bleaching Sector

    Science.gov (United States)

    Bilgin, Oyku

    2017-12-01

    In the sector of oil bleaching, the stored raw oil is subjected to physical and chemical methods such as degumming, neutralization, bleaching, deodorization and winterization. In the process of oil bleaching, the selection of correct bleaching earth in accordance with oil characteristics matters so much. Bleaching earth is an inorganic product used in removing impurities being available within the structures of vegetable, animal oil (sunflower, soya, corn, palm, tallow, rapeseed, fish oils…etc.) and fatty acids, mineral oils (glycerine, paraffin, mineral motor oils. etc.) with the adsorption process. The factors such as low cost of oil bleaching earth, low ratio of oil retaining, high bleaching capacity in spite of using them in small amounts, filter’s delayed blocking by the earth and non-increase of the free acidity of the oil should be taken into consideration. Bleaching earths are processed with some acids in order to widen their surface areas. During this process, a certain amount of acid is left within oil bleaching earths even if it is very little. These acids also increase oil’s acidity by oxidizing oil in the course of bleaching process. In this study, zeolite sample taken from Manisa -Demirci region was used. Following the processes of crushing and sieving, zeolite sample was subjected to chemical analyses according to their grain thickness, microscopic examination, the analyses of XRD and cation exchange capacity and their ore characteristics were determined. Afterwards, it was searched whether zeolite sample has oil bleaching ability or not or whether it can be used as oil bleaching earth or not.

  12. Influence of remineralizing gels on bleached enamel microhardness in different time intervals.

    Science.gov (United States)

    Borges, Alessandra Bühler; Yui, Karen Cristina Kazue; D'Avila, Thaís Corrêa; Takahashi, Camila Lurie; Torres, Carlos Rocha Gomes; Borges, Alexandre Luis Souto

    2010-01-01

    This study evaluated the influence of bleaching gel pH, the effect of applying remineralizing gels after bleaching and the effect of artificial saliva on enamel microhardness. Seventy bovine incisors were divided into three groups: Group 1 (n=10) received no bleaching procedure (control); Group 2 was bleached with a 35% hydrogen peroxide neutral gel (n=30) and Group 3 was bleached with a 35% hydrogen peroxide acid gel (n=30). Each experimental group was subdivided into three groups (n=10) according to the post-bleaching treatment: storage in artificial saliva, application of a fluoride gel and application of a combination of calcium and fluoride gel. The specimens were stored in artificial saliva for 7, 15 and 30 days and enamel microhardness was evaluated. The Vickers microhardness data were analyzed by three-way RM ANOVA, which revealed a significant difference only for treatment factor. The Tukey's test showed that the groups bleached followed by no additional treatment exhibited microhardness means significantly lower than the bleached groups treated with remineralizing gels. The Dunnet's test showed a significant difference only for the group bleached with acid gel without remineralizing treatment compared to the control group measured immediately after bleaching. It was concluded that acid bleaching gel significantly reduced enamel microhardness and that use of remineralizing gels after bleaching can significantly enhance the microhardness of bleached enamel.

  13. Comparative clinical study of the effectiveness of different dental bleaching methods - two year follow-up

    Directory of Open Access Journals (Sweden)

    Rafael Francisco Lia Mondelli

    2012-08-01

    Full Text Available This study evaluated color change, stability, and tooth sensitivity in patients submitted to different bleaching techniques. MATERIAL AND METHODS: In this study, 48 patients were divided into five groups. A half-mouth design was conducted to compare two in-office bleaching techniques (with and without light activation: G1: 35% hydrogen peroxide (HP (Lase Peroxide - DMC Equipments, São Carlos, SP, Brazil + hybrid light (HL (LED/Diode Laser, Whitening Lase II DMC Equipments, São Carlos, SP, Brazil; G2: 35% HP; G3: 38% HP (X-traBoost - Ultradent, South Jordan UT, USA + HL; G4: 38% HP; and G5: 15% carbamide peroxide (CP (Opalescence PF - Ultradent, South Jordan UT, USA. For G1 and G3, HP was applied on the enamel surface for 3 consecutive applications activated by HL. Each application included 3x3' HL activations with 1' between each interval; for G2 and G4, HP was applied 3x15' with 15' between intervals; and for G5, 15% CP was applied for 120'/10 days at home. A spectrophotometer was used to measure color change before the treatment and after 24 h, 1 week, 1, 6, 12, 18 and 24 months. A VAS questionnaire was used to evaluate tooth sensitivity before the treatment, immediately following treatment, 24 h after and finally 1 week after. RESULTS: Statistical analysis did not reveal any significant differences between in-office bleaching with or without HL activation related to effectiveness; nevertheless the time required was less with HL. Statistical differences were observed between the results after 24 h, 1 week and 1, 6, 12, 18 and 24 months (intergroup. Immediately, in-office bleaching increased tooth sensitivity. The groups activated with HL required less application time with gel. CONCLUSION: All techniques and bleaching agents used were effective and demonstrated similar behaviors.

  14. Recovery of cat retinal ganglion cell sensitivity following pigment bleaching.

    Science.gov (United States)

    Bonds, A B; Enroth-Cugell, C

    1979-01-01

    1. The threshold illuminance for small spot stimulation of on-centre cat retinal ganglion cells was plotted vs. time after exposure to adapting light sufficiently strong to bleach significant amounts of rhodopsin. 2. When the entire receptive field of an X- or Y-type ganglion cell is bleached by at most 40%, recovery of the cell's rod-system proceeds in two phases: an early relatively fast one during which the response appears transient, and a late, slower one during which responses become more sustained. Log threshold during the later phase is well fit by an exponential in time (tau = 11.5-38 min). 3. After bleaches of 90% of the underlying pigment, threshold is cone-determined for as long as 40 min. Rod threshold continues to decrease for at least 85 min after the bleach. 4. The rate of recovery is slower after strong than after weak bleaches; 10 and 90% bleaches yield time constants for the later phase of 11.5 and 38 min, respectively. This contrasts with an approximate time constant of 11 min for rhodopsin regeneration following any bleach. 5. The relationship between the initial elevation of log rod threshold extrapolated from the fitted exponential curves and the initial amount of pigment bleached is monotonic, but nonlinear. 6. After a bleaching exposure, the maintained discharge is initially very regular. The firing rate first rises, then falls to the pre-bleach level, with more extended time courses of change in firing rate after stronger exposures. The discharge rate is restored before threshold has recovered fully. 7. The change in the response vs. log stimulus relationship after bleaching is described as a shift of the curve to the right, paired with a decrease in slope of the linear segment of the curve. PMID:521963

  15. Ion release from a composite resin after exposure to different 10% carbamide peroxide bleaching agents

    Directory of Open Access Journals (Sweden)

    Renata Plá Rizzolo Bueno

    2012-06-01

    Full Text Available OBJECTIVE: This in vitro study evaluated the influence of two 10% carbamide peroxide bleaching agents - a commercial product (Opalescence PF; Ultradent Products, Inc. and a bleaching agent prepared in a compounding pharmacy - on the chemical degradation of a light-activated composite resin by determining its release of ions before and after exposure to the agents. MATERIAL AND METHODS: Thirty composite resin (Filtek Z250; 3M/ESPE samples were divided into three groups: group I (exposed to Opalescence PF commercial bleaching agent, group II (exposed to a compounded bleaching agent and group III (control - Milli-Q water. After 14 days of exposure, with a protocol of 8 h of daily exposure to the bleaching agents and 16 h of immersion in Milli-Q water, the analysis of ion release was carried out using a HP 8453 spectrophotometer. The values were analyzed statistically by ANOVA, Tukey's test and the paired t-tests. The significance level was set at 5%. RESULTS: After 14 days of the experiment, statistically significant difference was found between group II and groups I and III, with greater ion release from the composite resin in group II. CONCLUSIONS: The compounded bleaching agent had a more aggressive effect on the composite resin after 14 days of exposure than the commercial product and the control (no bleaching.

  16. Unprecedented mass bleaching and loss of coral across 12° of latitude in Western Australia in 2010-11.

    Science.gov (United States)

    Moore, James A Y; Bellchambers, Lynda M; Depczynski, Martial R; Evans, Richard D; Evans, Scott N; Field, Stuart N; Friedman, Kim J; Gilmour, James P; Holmes, Thomas H; Middlebrook, Rachael; Radford, Ben T; Ridgway, Tyrone; Shedrawi, George; Taylor, Heather; Thomson, Damian P; Wilson, Shaun K

    2012-01-01

    Globally, coral bleaching has been responsible for a significant decline in both coral cover and diversity over the past two decades. During the summer of 2010-11, anomalous large-scale ocean warming induced unprecedented levels of coral bleaching accompanied by substantial storminess across more than 12° of latitude and 1200 kilometers of coastline in Western Australia (WA). Extreme La-Niña conditions caused extensive warming of waters and drove considerable storminess and cyclonic activity across WA from October 2010 to May 2011. Satellite-derived sea surface temperature measurements recorded anomalies of up to 5°C above long-term averages. Benthic surveys quantified the extent of bleaching at 10 locations across four regions from tropical to temperate waters. Bleaching was recorded in all locations across regions and ranged between 17% (±5.5) in the temperate Perth region, to 95% (±3.5) in the Exmouth Gulf of the tropical Ningaloo region. Coincident with high levels of bleaching, three cyclones passed in close proximity to study locations around the time of peak temperatures. Follow-up surveys revealed spatial heterogeneity in coral cover change with four of ten locations recording significant loss of coral cover. Relative decreases ranged between 22%-83.9% of total coral cover, with the greatest losses in the Exmouth Gulf. The anomalous thermal stress of 2010-11 induced mass bleaching of corals along central and southern WA coral reefs. Significant coral bleaching was observed at multiple locations across the tropical-temperate divide spanning more than 1200 km of coastline. Resultant spatially patchy loss of coral cover under widespread and high levels of bleaching and cyclonic activity, suggests a degree of resilience for WA coral communities. However, the spatial extent of bleaching casts some doubt over hypotheses suggesting that future impacts to coral reefs under forecast warming regimes may in part be mitigated by southern thermal refugia.

  17. 21 CFR 872.6475 - Heat source for bleaching teeth.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Heat source for bleaching teeth. 872.6475 Section... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6475 Heat source for bleaching teeth. (a) Identification. A heat source for bleaching teeth is an AC-powered device that consists of a...

  18. A global protocol for monitoring of coral bleaching

    OpenAIRE

    Oliver, J.; Setiasih, N.; Marshall, P.; Hansen, L.

    2004-01-01

    Coral bleaching and subsequent mortality represent a major threat to the future health and productivity of coral reefs. However a lack of reliable data on occurrence, severity and other characteristics of bleaching events hampers research on the causes and consequences of this important phenomenon. This article describes a global protocol for monitoring coral bleaching events, which addresses this problem and can be used by people with different levels of expertise and resources.

  19. Annual coral bleaching and the long-term recovery capacity of coral.

    Science.gov (United States)

    Schoepf, Verena; Grottoli, Andréa G; Levas, Stephen J; Aschaffenburg, Matthew D; Baumann, Justin H; Matsui, Yohei; Warner, Mark E

    2015-11-22

    Mass bleaching events are predicted to occur annually later this century. Nevertheless, it remains unknown whether corals will be able to recover between annual bleaching events. Using a combined tank and field experiment, we simulated annual bleaching by exposing three Caribbean coral species (Porites divaricata, Porites astreoides and Orbicella faveolata) to elevated temperatures for 2.5 weeks in 2 consecutive years. The impact of annual bleaching stress on chlorophyll a, energy reserves, calcification, and tissue C and N isotopes was assessed immediately after the second bleaching and after both short- and long-term recovery on the reef (1.5 and 11 months, respectively). While P. divaricata and O. faveolata were able to recover from repeat bleaching within 1 year, P. astreoides experienced cumulative damage that prevented full recovery within this time frame, suggesting that repeat bleaching had diminished its recovery capacity. Specifically, P. astreoides was not able to recover protein and carbohydrate concentrations. As energy reserves promote bleaching resistance, failure to recover from annual bleaching within 1 year will likely result in the future demise of heat-sensitive coral species. © 2015 The Author(s).

  20. Taxonomic, Spatial and Temporal Patterns of Bleaching in Anemones Inhabited by Anemonefishes

    KAUST Repository

    Hobbs, Jean-Paul A.

    2013-08-08

    Background:Rising sea temperatures are causing significant destruction to coral reef ecosystems due to coral mortality from thermally-induced bleaching (loss of symbiotic algae and/or their photosynthetic pigments). Although bleaching has been intensively studied in corals, little is known about the causes and consequences of bleaching in other tropical symbiotic organisms.Methodology/Principal Findings:This study used underwater visual surveys to investigate bleaching in the 10 species of anemones that host anemonefishes. Bleaching was confirmed in seven anemone species (with anecdotal reports of bleaching in the other three species) at 10 of 19 survey locations spanning the Indo-Pacific and Red Sea, indicating that anemone bleaching is taxonomically and geographically widespread. In total, bleaching was observed in 490 of the 13,896 surveyed anemones (3.5%); however, this percentage was much higher (19-100%) during five major bleaching events that were associated with periods of elevated water temperatures and coral bleaching. There was considerable spatial variation in anemone bleaching during most of these events, suggesting that certain sites and deeper waters might act as refuges. Susceptibility to bleaching varied between species, and in some species, bleaching caused reductions in size and abundance.Conclusions/Significance:Anemones are long-lived with low natural mortality, which makes them particularly vulnerable to predicted increases in severity and frequency of bleaching events. Population viability will be severely compromised if anemones and their symbionts cannot acclimate or adapt to rising sea temperatures. Anemone bleaching also has negative effects to other species, particularly those that have an obligate relationship with anemones. These effects include reductions in abundance and reproductive output of anemonefishes. Therefore, the future of these iconic and commercially valuable coral reef fishes is inextricably linked to the ability of host

  1. Taxonomic, Spatial and Temporal Patterns of Bleaching in Anemones Inhabited by Anemonefishes

    KAUST Repository

    Hobbs, Jean-Paul A.; Frisch, Ashley J.; Ford, Benjamin M.; Thums, Michele; Saenz Agudelo, Pablo; Furby, Kathryn A.; Berumen, Michael L.

    2013-01-01

    Background:Rising sea temperatures are causing significant destruction to coral reef ecosystems due to coral mortality from thermally-induced bleaching (loss of symbiotic algae and/or their photosynthetic pigments). Although bleaching has been intensively studied in corals, little is known about the causes and consequences of bleaching in other tropical symbiotic organisms.Methodology/Principal Findings:This study used underwater visual surveys to investigate bleaching in the 10 species of anemones that host anemonefishes. Bleaching was confirmed in seven anemone species (with anecdotal reports of bleaching in the other three species) at 10 of 19 survey locations spanning the Indo-Pacific and Red Sea, indicating that anemone bleaching is taxonomically and geographically widespread. In total, bleaching was observed in 490 of the 13,896 surveyed anemones (3.5%); however, this percentage was much higher (19-100%) during five major bleaching events that were associated with periods of elevated water temperatures and coral bleaching. There was considerable spatial variation in anemone bleaching during most of these events, suggesting that certain sites and deeper waters might act as refuges. Susceptibility to bleaching varied between species, and in some species, bleaching caused reductions in size and abundance.Conclusions/Significance:Anemones are long-lived with low natural mortality, which makes them particularly vulnerable to predicted increases in severity and frequency of bleaching events. Population viability will be severely compromised if anemones and their symbionts cannot acclimate or adapt to rising sea temperatures. Anemone bleaching also has negative effects to other species, particularly those that have an obligate relationship with anemones. These effects include reductions in abundance and reproductive output of anemonefishes. Therefore, the future of these iconic and commercially valuable coral reef fishes is inextricably linked to the ability of host

  2. Bleach vs. Bacteria

    Science.gov (United States)

    ... Articles | Inside Life Science Home Page Bleach vs. Bacteria By Sharon Reynolds Posted April 2, 2014 Your ... hypochlorous acid to help kill invading microbes, including bacteria. Researchers funded by the National Institutes of Health ...

  3. Sodium Hydroxide and Calcium Hydroxide Hybrid Oxygen Bleaching with System

    Science.gov (United States)

    Doelle, K.; Bajrami, B.

    2018-01-01

    This study investigates the replacement of sodium hydroxide in the oxygen bleaching stage using a hybrid system consisting of sodium hydroxide calcium hydroxide. Commercial Kraft pulping was studied using yellow pine Kraft pulp obtained from a company in the US. The impact of sodium hydroxide, calcium hydroxide hybrid system in regard to concentration, reaction time and temperature for Kraft pulp was evaluated. The sodium hydroxide and calcium hydroxide dosage was varied between 0% and 15% based on oven dry fiber content. The bleaching reaction time was varied between 0 and 180 minutes whereas the bleaching temperature ranged between 70 °C and 110 °C. The ability to bleach pulp was measured by determining the Kappa number. Optimum bleaching results for the hybrid system were achieved with 4% sodium hydroxide and 2% calcium hydroxide content. Beyond this, the ability to bleach pulp decreased.

  4. Tooth Bleaching: Current Concepts of the Procedure in Cosmetic ...

    African Journals Online (AJOL)

    Less caustic agents more recently introduced, in the late 1900s, have revived the interest of the dental profession in the art of tooth bleaching. These agents are now being packaged as bleaching kits, which may be used for in-office bleaching by the dentist or used at home by the patient under the supervision of the dentist.

  5. Symbiotic immuno-suppression: is disease susceptibility the price of bleaching resistance?

    Science.gov (United States)

    Merselis, Daniel G; Lirman, Diego; Rodriguez-Lanetty, Mauricio

    2018-01-01

    Accelerating anthropogenic climate change threatens to destroy coral reefs worldwide through the processes of bleaching and disease. These major contributors to coral mortality are both closely linked with thermal stress intensified by anthropogenic climate change. Disease outbreaks typically follow bleaching events, but a direct positive linkage between bleaching and disease has been debated. By tracking 152 individual coral ramets through the 2014 mass bleaching in a South Florida coral restoration nursery, we revealed a highly significant negative correlation between bleaching and disease in the Caribbean staghorn coral, Acropora cervicornis . To explain these results, we propose a mechanism for transient immunological protection through coral bleaching: removal of Symbiodinium during bleaching may also temporarily eliminate suppressive symbiont modulation of host immunological function. We contextualize this hypothesis within an ecological perspective in order to generate testable predictions for future investigation.

  6. Effectiveness of bleaching agent on composite resin discoloration

    Directory of Open Access Journals (Sweden)

    Galih Sampoerno

    2012-03-01

    Full Text Available Background: The discoloration of teeth, especially anterior teeth, is one of aesthetic problems. The use of tooth bleaching agents for discolored natural teeth is becoming increasingly popular. Many dentists, however, get many problems when they conduct bleaching process since there is much composite filling on patient’s anterior teeth. Although many research have focused on the discoloration of composite resin after bleaching process, the problem still becomes debatable. Purpose: The purpose of this study was to investigate the difference of the discoloration between hybrid composite and nano composite before and after the application of tooth bleaching agent, 38% hydrogen peroxide. Methods: Eighteen disk-shaped specimens (5 mm of each of two composite resins, hybrid and nano filler, were prepared. The each group was treated 3 times and the specimens were divided into two groups consisted of 9 specimens for each, and then immersed in black tea solutions for 72 hours. Next, after having staining and bleaching processes, the color of the specimens was measured with a optic spectrophotometer by using photo with type BPY-47 and digital microvolt. The differences of the light intensity among three measurements were then calculated. Afterwards, GLM MANOVA Repeated Measure and parametric analysis (Independent t-test and Paired t-test were then used to analyze the data. Results: After staining process, it is then known that the nano composite had more discoloration and more affected by the black tea solution than the hybrid one. Conclusion: After bleaching, the discoloration was finally removed completely from both hybride and nano filler composite resins and became brighter from the baseline color.Latar belakang: Salah satu problem estetik adalah adanya perubahan warna pada gigi anterior. Peningkatan pemakaian bahan bleaching semakin popular. Banyak dokter gigi mempunyai problem ketika mereka akan melakukan proses bleaching dan ditemukan banyak

  7. Chemi-thermomechanical pulping of para rubber waste wood

    Energy Technology Data Exchange (ETDEWEB)

    Kubo, T.; Hosokawa, J.; Kobayashi, T.; Kobayashi, Y.

    1981-01-01

    The addition of NaOH to Na/sub 2/SO/sub 3/-treated waste wood chips (Hevea brasiliensis) increased long fiber fraction, Klason lignin content and bulk density, improved breaking length and tear factor, and decreased energy consumption in refining and brightness of resulting chemithermomechanical pulp. Lowering in brightness by alkali treatment was recovered by H/sub 2/O/sub 2/ bleaching, and bleaching with 8% H/sub 2/O/sub 2/ on pulp gave pulp with 61.3% brightness.

  8. REMINERALIZATION POTENTIAL OF A CARBAMIDE BLEACHING AGENT

    Directory of Open Access Journals (Sweden)

    Marinova-Takorova Borislavova Mirela

    2016-03-01

    Full Text Available Background: Bleaching has gradually became a popular procedure for people searching for aesthetic improvement. The aim of this in vitro study was to investigate the effect of bleaching with 45% carbamide peroxide on the level of mineralization of enamel, using laser fluorescence. Materials and methods: Sixty extracted human teeth were treated with 45% carbamid peroxide (Opalescence, Ultradent, 4 consecutive days for one hour each day. The effect of the bleaching agent on the level of mineralization of enamel was measured with DIAGNO dent pen. The statistical method we use was descriptive analysis. Results: The average values, measured before the applications of the carbamid peroxide were 6.33. On the first day they were 5.41, on the second 5.38, on the third 5.11 and 5.35 on the forth. Conclusion: There was observed a slight remineralization effect due to the incorporated Ca2+ and F- ions in the bleaching agent that we have used.

  9. In-Office Bleaching During Orthodontic Treatment.

    Science.gov (United States)

    Gomes, Mauricio Neves; Dutra, Hélio; Morais, Alexandre; Sgura, Ricardo; Devito-Moraes, André Guaraci

    2017-04-01

    To demonstrate that it is possible to pursue teeth whitening treatment protocols during orthodontic treatment with no esthetic loss. Many patients undergoing orthodontic treatment desire to have a straight and well aligned dentition, but also whiter teeth. For many years, it was believed that carrying out a whitening treatment with positioned orthodontic brackets in place would result in localized spots on the enamel labial surfaces of teeth. However, a deeper understanding of the bleaching process suggests that the oxidation caused by products, which results from hydrogen peroxide decomposition, are able to diffuse peripherally into the tooth structure and reach even that under the cemented brackets. Two in-office-bleaching treatments were performed in patients using orthodontic fixed braces in two or three 40-minute sessions using a 35% hydrogen peroxide. In-office bleaching is possible and effective, even with orthodontic brackets in position. The teeth were successfully bleached despite the presence of brackets. All biological criteria have been fulfilled satisfying patients' expectations of aligned and whitened teeth in less time than if treatments had been performed separately, with satisfactory results and no esthetic loss. The whitening of teeth is possible during orthodontic treatment with fixed braces without any esthetic loss. The in-office bleaching treatment with brackets in position also may act as a motivation factor, preventing patient withdrawal or treatment interruption. Therefore, at the end of the orthodontic treatment, the patient is able to display an aligned, functional and whitened smile. (J Esthet Restor Dent 29:83-92, 2017). © 2016 Wiley Periodicals, Inc.

  10. Bleaching of reef coelenterates in the San Blas Islands, Panama

    Science.gov (United States)

    Lasker, Howard R.; Peters, Esther C.; Coffroth, Mary Alice

    1984-12-01

    Starting in June 1983, 25 species of hermatypic corals, gorgonians, hydrocorals, anemones and zoanthids in the San Blas Islands, Panama, began showing signs of a loss of colour leading in some cases to a white “bleached” appearance. Histologic examination of six coral species indicated that bleaching was associated with drastic reductions in the density of zooxanthellae and with the atrophy and necrosis of the animal tissue. The severity of the bleaching varied among species and many species were unaffected. The species most extensively affected were: Agaricia spp., which became completely bleached and frequently died; Montastraea annularis which bleached and continued to survive; and Millepora spp. which bleached white but quickly regained their colouration. Shallow reefs dominated by Agaricia spp. suffered the most extensive bleaching. At one site, Pico Feo, 99% of the Agaricia (32% of the living cover) was bleached. On fore reers, which were dominated by Agaricia spp. and M. annularis, the proportion of M. annularis bleached ranged from 18 to 100% and that of Agaricia spp. from 30 to 53%. Transects at Sail Rock and House Reef were surveyed in August 1983 and January 1984. At those sites, 53% of the Agaricia cover died between August and January. The remaining living cover of Agaricia and of all other species exhibited normal colouration in January. Salinity and temperature were monitored every second day at 4 m depth between May 10 and August 28, 1983 at one of the localities. Bleaching was first observed within two weeks of a 2 °C rise in temperature which occurred in late May 1983. Temperatures remained at or above 31.5 °C for the following 3 weeks and were at or above 30 °C for an additional 4 weeks. The bleaching of corals in the San Blas was most likely due to those elevanted temperatures.

  11. Comparative performance evaluation of conventional and ultrasonic assisted bleaching of cotton fabric

    International Nuclear Information System (INIS)

    Farooq, A.; Ashraf, M.A.

    2013-01-01

    Summary: Conventional bleaching process is an important and quality influencing process for textile wet processors. However, the process requires high energy consumption, and is slow and time consuming. In the present research work, cotton woven fabric was bleached with different bleaching agents using conventional and ultrasonic assisted techniques. After bleaching whiteness index, weight loss and tensile strength of samples were measured and compared statistically. The results showed that ultrasonic energy intensifies the diffusion of chemicals and increases the production of hydroxyl radicals which catalyze the bleaching process. Ultrasonic assisted bleaching proved to be a novel technique that can produce better results than conventional bleaching process even at low temperature and in less time. (author)

  12. THE BLEACHING SYNDROME: MANIFESTATION OF A POST ...

    African Journals Online (AJOL)

    User

    universal and extends to the Americas and elsewhere impacted by colonial influences. Without exception .... "They say we should stop bleaching because of skin cancer and skin disease. ... Kenya, activists moved to have a ban put on the sale of skin bleaching creams. In agreement .... socioeconomic standing. Furthermore ...

  13. The Influence of Post Bleaching Treatments in Stain Absorption and Microhardness.

    Science.gov (United States)

    Moosavi, Horieh; Darvishzadeh, Fatemeh

    2016-01-01

    This study investigated the effects of post bleaching treatments to prevent restaining and the change of enamel surface microhardness after dental bleaching in vitro. Sixty intact human incisor teeth were stained in tea solution and randomly assigned into four groups (n=15). Then samples were bleached for two weeks (8 hours daily) by 15% carbamide peroxide. Tooth color was determined both with a spectrophotometer and visually before bleaching (T1) and immediately after bleaching (T2). Next, it was applied in group 1 fluoride (Naf 2%) gel for 2 minutes, and in group 2 a fractional CO2 laser (10 mJ, 200 Hz, 10 s), and in group 3, nanohydroxyapatite gel for 2 minutes. The bleached teeth in group 4 remained untreated (control group). Then teeth placed in tea solution again. Color examinations were repeated after various post bleaching treatments (T3) and restaining with tea (T4) and color change values recorded. The microhardness was measured at the enamel surface of samples. Data was analyzed using ANOVA, Tukey HSD test and Dunnett T3 (α = 0.05). Directly after bleaching (ΔE T3-T2), the treatment with nanohydroxyapatite showed significantly the least color lapse in colorimetric evaluation. In experimental groups, the color change between T3 and T4 stages (ΔE T4-T3) was significantly lower than control group (P bleaching treatments are suggested for prevention of stain absorption and increasing the hardening of bleached enamel.

  14. Susceptibility of central Red Sea corals during a major bleaching event

    KAUST Repository

    Furby, Kathryn A.

    2013-01-04

    A major coral bleaching event occurred in the central Red Sea near Thuwal, Saudi Arabia, in the summer of 2010, when the region experienced up to 10-11 degree heating weeks. We documented the susceptibility of various coral taxa to bleaching at eight reefs during the peak of this thermal stress. Oculinids and agaricids were most susceptible to bleaching, with up to 100 and 80 % of colonies of these families, respectively, bleaching at some reefs. In contrast, some families, such as mussids, pocilloporids, and pectinids showed low levels of bleaching (<20 % on average). We resurveyed the reefs 7 months later to estimate subsequent mortality. Mortality was highly variable among taxa, with some taxa showing evidence of full recovery and some (e. g., acroporids) apparently suffering nearly complete mortality. The unequal mortality among families resulted in significant change in community composition following the bleaching. Significant factors in the likelihood of coral bleaching during this event were depth of the reef and distance of the reef from shore. Shallow reefs and inshore reefs had a higher prevalence of bleaching. This bleaching event shows that Red Sea reefs are subject to the same increasing pressures that reefs face worldwide. This study provides a quantitative, genus-level assessment of the vulnerability of various coral groups from within the Red Sea to bleaching and estimates subsequent mortality. As such, it can provide valuable insights into the future for reef communities in the Red Sea. © 2013 Springer-Verlag Berlin Heidelberg.

  15. Inhibition of photosynthetic CO₂ fixation in the coral Pocillopora damicornis and its relationship to thermal bleaching.

    Science.gov (United States)

    Hill, Ross; Szabó, Milán; ur Rehman, Ateeq; Vass, Imre; Ralph, Peter J; Larkum, Anthony W D

    2014-06-15

    Two inhibitors of the Calvin-Benson cycle [glycolaldehyde (GA) and potassium cyanide (KCN)] were used in cultured Symbiodinium cells and in nubbins of the coral Pocillopora damicornis to test the hypothesis that inhibition of the Calvin-Benson cycle triggers coral bleaching. Inhibitor concentration range-finding trials aimed to determine the appropriate concentration to generate inhibition of the Calvin-Benson cycle, but avoid other metabolic impacts to the symbiont and the animal host. Both 3 mmol l(-1) GA and 20 μmol l(-1) KCN caused minimal inhibition of host respiration, but did induce photosynthetic impairment, measured by a loss of photosystem II function and oxygen production. GA did not affect the severity of bleaching, nor induce bleaching in the absence of thermal stress, suggesting inhibition of the Calvin-Benson cycle by GA does not initiate bleaching in P. damicornis. In contrast, KCN did activate a bleaching response through symbiont expulsion, which occurred in the presence and absence of thermal stress. While KCN is an inhibitor of the Calvin-Benson cycle, it also promotes reactive oxygen species formation, and it is likely that this was the principal agent in the coral bleaching process. These findings do not support the hypothesis that temperature-induced inhibition of the Calvin-Benson cycle alone induces coral bleaching. © 2014. Published by The Company of Biologists Ltd.

  16. Tooth-bleaching procedures and their controversial effects: A literature review

    Science.gov (United States)

    Alqahtani, Mohammed Q.

    2014-01-01

    Aim This review article will help clinicians improve their understanding of the history of bleaching procedures, bleaching types, components, mechanisms, and their effects on soft tissue, tooth structures, resin composite, and bonding. Methods The controversial issues about bleaching procedures and their effects are reviewed. Additionally, the consequences of pre- and post-bleaching on the bonding potential of composite resin restorations to tooth structure are discussed. Conclusion The overall goal of the paper is to help reduce risks for patients. PMID:25408594

  17. Thermal stress exposure, bleaching response, and mortality in the threatened coral Acropora palmata.

    Science.gov (United States)

    Williams, D E; Miller, M W; Bright, A J; Pausch, R E; Valdivia, A

    2017-11-15

    Demographic data for Elkhorn coral, Acropora palmata, and in situ water temperature data from seven upper Florida Keys (USA) reefs revealed three warm thermal stress events between 2010 and 2016. During a mild bleaching event in 2011, up to 59% of colonies bleached, but no mortality resulted. In both 2014 and 2015, severe and unprecedented bleaching was observed with up to 100% of colonies bleached. A. palmata live tissue cover declined by one-third following the 2014-2015 events. Colony mortality of mildly- and non-bleached colonies did not differ but increased significantly with more severe bleaching. Increased bleaching prevalence corresponded to maximum daily average water temperatures above 31.3°C. However, the cumulative days with daily average exceeding 31.0°C provided a better predictor of bleaching response. The bleaching response of surviving colonies in 2015 was not consistent with acclimatization as most individual colonies bleached at least as badly as in 2014. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. The 2014 summer coral bleaching event in subtropical Hong Kong.

    Science.gov (United States)

    Xie, James Y; Lau, Dickey C C; Kei, Keith; Yu, Vriko P F; Chow, Wing-Kuen; Qiu, Jian-Wen

    2017-11-30

    We reported a coral bleaching event that occurred in August-September 2014 in Hong Kong waters based on video transect surveys conducted at eight sites. The bleaching affected eight species of corals with different growth forms. Bleaching at seven of the eight study sites was minor, affecting only 0.4-5.2% colonies and 0.8-10.0% coral-covered area. Sharp Island East, however, suffered from a moderate level of bleaching, with 13.1% colonies and 30.1% coral-covered area affected. Examination of the government's environmental monitoring data indicated abnormal water quality conditions preceding and during the bleaching event. Follow-up field surveys of tagged colonies showed that 76% of them had fully recovered, 12% partially recovered, and 12% suffered from mortality. These results indicate that the subtropical corals of Hong Kong are not immune to bleaching, and there is a need to study their responses under climate change scenarios. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. In-office dental bleaching with light vs. without light: A systematic review and meta-analysis.

    Science.gov (United States)

    Maran, Bianca Medeiros; Burey, Adrieli; de Paris Matos, Thalita; Loguercio, Alessandro D; Reis, Alessandra

    2018-03-01

    A systematic review and meta-analysis were performed to answer the following research question: Does light-activated in-office vital bleaching have a greater whitening efficacy and higher tooth sensitivity (TS) in comparison with in-office vital bleaching without light when used in adults? Only randomized clinical trials (RCTs) involving adults who had in-office bleaching with and without light activation were included. Controlled vocabulary and keywords were used in a comprehensive search for titles and abstracts in PubMed, and this search was adapted for Scopus, Web of Science, LILACS, BBO, Cochrane Library, and SIGLE without restrictions in May 2016 and was updated in August 2017. IADR abstracts (1990-2016), unpublished- and ongoing-trial registries, dissertations, and theses were also searched. The risk-of-bias tool of the Cochrane Collaboration was used for quality assessment. The quality of the evidence was rated using the Grading of Recommendations: Assessment, Development, and Evaluation approach. Through the use of the random effects model, a meta-analysis with a subgroup analysis (low and high hydrogen peroxide concentration) was conducted for color change (ΔE*, ΔSGU) as well as the risk and intensity of TS. We retrieved 6663 articles, but after removing duplicates and non-relevant articles, only 21 RCTs remained. No significant difference in ΔE*, ΔSGU, and risk and intensity of TS was observed (p > .05). For ΔE and risk of TS, the quality of the evidence was graded as moderate whereas the evidence for ΔSGU and intensity of TS was graded as very low and low, respectively. Without considering variations in the protocols, the activation of in-office bleaching gel with light does not seem to improve color change or affect tooth sensitivity, regardless of the hydrogen peroxide concentration. (PROSPERO - CRD42016037630). Although it is commercially claimed that in-office bleaching associated with light improves and accelerates color change, this

  20. Tooth bleaching and young adults in Nigeria: knowledge, experiences and intention.

    Science.gov (United States)

    Azodo, C C; Ogbomo, A C; Agbor, M A

    2012-12-01

    To assess the knowledge, experiences and intention to have tooth bleaching among young adults studying in a Nigerian University. A cross-section of part-time undergraduate students of University of Benin, Benin City, Nigeria were studied in 2010 using a self-administered questionnaire. About three-quarters 289 (72.4%) of the respondents reported awareness of at least one cause of tooth discoloration. A total of 143 (35.8%) of the respondents have heard of tooth bleaching with main sources of information being friends/relatives, dentists and the internet. One-third 132 (33.1%) of the respondents correctly identified that the aim of tooth bleaching was to make the teeth whiter. The respondents that had correct knowledge about mechanism, duration and complications of tooth bleaching were 51 (12.8%), 25 (6.3%) and 35 (8.8%) respectively. The major perceived benefits of tooth bleaching reported by the respondents were self confidence boost 152 (38.1%) and improvement of one's beauty 107 (26.8%). Out of the 68 (17.0%) respondents that have attempted tooth bleaching, 36 (52.9%) used tooth whitening toothpaste. Out of the 151 (37.8%) respondents that expressed intention of having tooth bleaching procedure, 32 (21.2%) would pursue the course, no matter the cost. In the studied population, knowledge of tooth discoloration was high, awareness and experiences of tooth bleaching were low but significant number expressed intention of having tooth bleaching. It is important that dentists increase oral health information particularly tooth bleaching information accessibility to the young adult population to improve the knowledge and prevent adverse effects.

  1. Effect of Toothpaste Application Prior to Dental Bleaching on Whitening Effectiveness and Enamel Properties.

    Science.gov (United States)

    Vieira-Junior, W F; Lima, D A N L; Tabchoury, C P M; Ambrosano, G M B; Aguiar, F H B; Lovadino, J R

    2016-01-01

    The purpose of this study was to investigate the effects on the enamel properties and effectiveness of bleaching using 35% hydrogen peroxide (HP) when applying toothpastes with different active agents prior to dental bleaching. Seventy enamel blocks (4 × 4 × 2 mm) were submitted to in vitro treatment protocols in a tooth-brushing machine (n=10): with distilled water and exposure to placebo gel (negative control [NC]) or HP bleaching (positive control [PC]); and brushing with differing toothpastes prior to HP bleaching, including potassium nitrate toothpaste (PN) containing NaF, conventional sodium monofluorophosphate toothpaste (FT), arginine-based toothpastes (PA and SAN), or a toothpaste containing bioactive glass (NM). Color changes were determined using the CIE L*a*b* system (ΔE, ΔL, Δa, and Δb), and a roughness (Ra) analysis was performed before and after treatments. Surface microhardness (SMH) and cross-sectional microhardness (CSMH) were analyzed after treatment. Data were analyzed with repeated measures ANOVA for Ra, one-way ANOVA (SMH, ΔE, ΔL, Δa, and Δb), split-plot ANOVA (CSMH), and Tukey post hoc test (α PA = SAN > all other groups) or decreased HP effects (CSMH). Ra increased in all bleached groups, with the exception of NM, which did not differ from the NC. The variation in the color variables (ΔL, Δa, and Δb) explained 21% of the variation in the physical surface variables (Ra and SMH). The application of toothpaste prior to dental bleaching did not interfere with the effectiveness of treatment. The bioactive glass based toothpaste protected the enamel against the deleterious effects of dental bleaching.

  2. Influence of bleaching agents on surface roughness of sound or eroded dental enamel specimens.

    Science.gov (United States)

    Azrak, Birgül; Callaway, Angelika; Kurth, Petra; Willershausen, Brita

    2010-12-01

    The aim of the present in vitro study was to assess the effect of bleaching agents on eroded and sound enamel specimens. Enamel specimens prepared from human permanent anterior teeth were incubated with different bleaching agents containing active ingredients as 7.5 or 13.5% hydrogen peroxide or 35% carbamide peroxide, ranging in pH from 4.9 to 10.8. The effect of the tooth whitening agents on surface roughness was tested for sound enamel surfaces as well as for eroded enamel specimens. To provoke erosive damage, the enamel specimens were incubated for 10 hours with apple juice (pH = 3.4). Afterwards, pretreated and untreated dental slices were incubated with one of the bleaching agents for 10 hours. The surface roughness (R(a)) of all enamel specimens (N = 80) was measured using an optical profilometric device. A descriptive statistical analysis of the R(a) values was performed. The study demonstrated that exposure to an acidic bleaching agent (pH = 4.9) resulted in a higher surface roughness (p = 0.043) than treatment with a high peroxide concentration (pH = 6.15). If the enamel surface was previously exposed to erosive beverages, subsequent bleaching may enhance damage to the dental hard tissue. Bleaching agents with a high concentration of peroxide or an acidic pH can influence the surface roughness of sound or eroded enamel. © 2010, COPYRIGHT THE AUTHORS. JOURNAL COMPILATION © 2010, WILEY PERIODICALS, INC.

  3. Treatment of the Bleaching Effluent from Sulfite Pulp Production by Ceramic Membrane Filtration

    Directory of Open Access Journals (Sweden)

    Mehrdad Ebrahimi

    2015-12-01

    Full Text Available Pulp and paper waste water is one of the major sources of industrial water pollution. This study tested the suitability of ceramic tubular membrane technology as an alternative to conventional waste water treatment in the pulp and paper industry. In this context, in series batch and semi-batch membrane processes comprising microfiltration, ultrafiltration and nanofiltration, ceramic membranes were developed to reduce the chemical oxygen demand (COD and remove residual lignin from the effluent flow during sulfite pulp production. A comparison of the ceramic membranes in terms of separation efficiency and performance revealed that the two-stage process configuration with microfiltration followed by ultrafiltration was most suitable for the efficient treatment of the alkaline bleaching effluent tested herein, reducing the COD concentration and residual lignin levels by more than 35% and 70%, respectively.

  4. Treatment of the Bleaching Effluent from Sulfite Pulp Production by Ceramic Membrane Filtration.

    Science.gov (United States)

    Ebrahimi, Mehrdad; Busse, Nadine; Kerker, Steffen; Schmitz, Oliver; Hilpert, Markus; Czermak, Peter

    2015-12-31

    Pulp and paper waste water is one of the major sources of industrial water pollution. This study tested the suitability of ceramic tubular membrane technology as an alternative to conventional waste water treatment in the pulp and paper industry. In this context, in series batch and semi-batch membrane processes comprising microfiltration, ultrafiltration and nanofiltration, ceramic membranes were developed to reduce the chemical oxygen demand (COD) and remove residual lignin from the effluent flow during sulfite pulp production. A comparison of the ceramic membranes in terms of separation efficiency and performance revealed that the two-stage process configuration with microfiltration followed by ultrafiltration was most suitable for the efficient treatment of the alkaline bleaching effluent tested herein, reducing the COD concentration and residual lignin levels by more than 35% and 70%, respectively.

  5. "Super-quenching" state protects Symbiodinium from thermal stress - Implications for coral bleaching.

    Science.gov (United States)

    Slavov, Chavdar; Schrameyer, Verena; Reus, Michael; Ralph, Peter J; Hill, Ross; Büchel, Claudia; Larkum, Anthony W D; Holzwarth, Alfred R

    2016-06-01

    The global rise in sea surface temperatures causes regular exposure of corals to high temperature and high light stress, leading to worldwide disastrous coral bleaching events (loss of symbiotic dinoflagellates (Symbiodinium) from reef-building corals). Our picosecond chlorophyll fluorescence experiments on cultured Symbiodinium clade C cells exposed to coral bleaching conditions uncovered the transformations of the alga's photosynthetic apparatus (PSA) that activate an extremely efficient non-photochemical "super-quenching" mechanism. The mechanism is associated with a transition from an initially heterogeneous photosystem II (PSII) pool to a homogeneous "spillover" pool, where nearly all excitation energy is transferred to photosystem I (PSI). There, the inherently higher stability of PSI and high quenching efficiency of P(700)(+) allow dumping of PSII excess excitation energy into heat, resulting in almost complete cessation of photosynthetic electron transport (PET). This potentially reversible "super-quenching" mechanism protects the PSA against destruction at the cost of a loss of photosynthetic activity. We suggest that the inhibition of PET and the consequent inhibition of organic carbon production (e.g. sugars) in the symbiotic Symbiodinium provide a trigger for the symbiont expulsion, i.e. bleaching. Copyright © 2016. Published by Elsevier B.V.

  6. Comparison of Radicular Peroxide Leakage from four Commonly used Bleaching agents following Intracoronal Bleaching in Endodontically treated teeth - An In Vitro Study.

    Science.gov (United States)

    Madhu, Ks; Hegde, Swaroop; Mathew, Sylvia; Lata, DA; Bhandi, Shilpa H; N, Shruthi

    2013-08-01

    Non vital bleaching is simple, conservative procedure for esthetic correction of discolored endodontically treated teeth. The aim of this study was to determine and compare the amount of peroxide leakage from four different bleaching agents i.e superoxol, sodium perborate, combination of superoxol & sodium perborate and carbamide peroxide during intracoronal bleaching, as the safe and effective bleaching is the need of the hour. 50 extracted maxillary centrals were selected for the study. Following standardized protocol access, cleaning and shaping by step back technique and obturation was done using guttapercha and AH plus sealer. Access was sealed with Cavit G and outer root surface was coated with wax and nail varnish. The teeth were separated into crown and root and the root portion was placed in plastic tube containing distilled water for 7days.After incubation, 3mm of gutta-percha was removed below CEJ and 2mm glass ionomer cement base was placed. Grouped into five categories based on the bleaching agent placed in pulp chamber as -group1 (control)-distilled water, group 2-sodium perborate with distilled water , group 3- 30% hydrogen peroxide ,group 4-mixture of sodium perborate and 30% hydrogen peroxide and group 5-10% carbamide peroxide gel. Peroxide leakage was measured after 24hrs using ferrothiocyanate method and optical density using spectrophotometer. Statistical analysis of the data was conducted using ANOVA and multiple comparisons within the groups was done using BONFERRONI method (Post-Hoc tests). The results showed highest peroxide penetration from 30% hydrogen peroxide followed by mixture of sodium perborate with 30% hydrogen peroxide, mixture of sodium perborate with distilled water and least penetration from 10% carbamide peroxide gel. The results were statistically significant. Radicular peroxide leakage in 10% carbamide peroxide was significantly lower than the other tested bleaching agents making it a very safe alternative for intracoronal

  7. Natural sunlight bleaching of the aluminum center in quartz

    International Nuclear Information System (INIS)

    Lin Min; Yin Gongming; Han Kongyan; Bao Jifei; Liu Jingwei; Jia Li

    2007-01-01

    The effect of sunlight bleaching on ESR signals from the aluminum center in quartz is reported for two samples of sand-sized quartz, one from a granite and one from a beach sand. The grains were exposed to direct sunlight for periods of time up to 500 h, with bleaching carried out in four different cities in China that are from 50 to 3600 m above sea level. Each sample bleached to the same residual level, ∼55% for the granite and 80% for the beach sand of the initial value after a 200 Gy dose had been given. After 200 h, the bleaching level reached was independent of the height above sea level

  8. Evaluation of peanut hulls as an alternative to bleaching clays

    Energy Technology Data Exchange (ETDEWEB)

    Hassanein, M. M.; El-Shami, S. M.; Taha, F. S.

    2011-07-01

    Peanut hulls (PNH) were carbonized at different temperatures, times, and evaluated at different concentrations as an alternative to bleaching clays. Evaluation of bleached crude soybean oil with PNH was based on their delta free fatty acids, reduction in peroxide value (PV), reduction in phospholipids (PL) and bleachability. The performance of several commercially used bleaching clays was evaluated, for comparison. Mixtures were formulated including: PNH and Tonsil -N (TN), PNH and Fuller's earth (FE) and PNH and O-passive (OP) and examined. The oxidative stability of oils was determined. Results for the investigated commercial bleaching clays revealed: TN > FE > F > TF > OP. Highest reduction in PV and PL, and highest bleachability were achieved for soybean oil bleached with 2% PNH carbonized at 500 degree centigrade for 30 min (PNH). Mixtures of PNH with the three chosen bleaching clays indicated that 1PNH : 2TN gave the highest bleachability. CSO was miscella bleached in hexane using PNH and resulted in an appreciable improvement in all oil characteristics, especially in bleachability. Oxidative stability of oils was in the following order: TN > control > FE > PNH with Induction period values of 23.1 > 6.43 > 5.73 > 2.85 h, respectively. (Author) 20 refs.

  9. Skeletal light-scattering accelerates bleaching response in reef-building corals.

    Science.gov (United States)

    Swain, Timothy D; DuBois, Emily; Gomes, Andrew; Stoyneva, Valentina P; Radosevich, Andrew J; Henss, Jillian; Wagner, Michelle E; Derbas, Justin; Grooms, Hannah W; Velazquez, Elizabeth M; Traub, Joshua; Kennedy, Brian J; Grigorescu, Arabela A; Westneat, Mark W; Sanborn, Kevin; Levine, Shoshana; Schick, Mark; Parsons, George; Biggs, Brendan C; Rogers, Jeremy D; Backman, Vadim; Marcelino, Luisa A

    2016-03-21

    At the forefront of ecosystems adversely affected by climate change, coral reefs are sensitive to anomalously high temperatures which disassociate (bleaching) photosynthetic symbionts (Symbiodinium) from coral hosts and cause increasingly frequent and severe mass mortality events. Susceptibility to bleaching and mortality is variable among corals, and is determined by unknown proportions of environmental history and the synergy of Symbiodinium- and coral-specific properties. Symbiodinium live within host tissues overlaying the coral skeleton, which increases light availability through multiple light-scattering, forming one of the most efficient biological collectors of solar radiation. Light-transport in the upper ~200 μm layer of corals skeletons (measured as 'microscopic' reduced-scattering coefficient, μ'(S,m)), has been identified as a determinant of excess light increase during bleaching and is therefore a potential determinant of the differential rate and severity of bleaching response among coral species. Here we experimentally demonstrate (in ten coral species) that, under thermal stress alone or combined thermal and light stress, low-μ'(S,m) corals bleach at higher rate and severity than high-μ'(S,m) corals and the Symbiodinium associated with low-μ'(S,m) corals experience twice the decrease in photochemical efficiency. We further modelled the light absorbed by Symbiodinium due to skeletal-scattering and show that the estimated skeleton-dependent light absorbed by Symbiodinium (per unit of photosynthetic pigment) and the temporal rate of increase in absorbed light during bleaching are several fold higher in low-μ'(S,m) corals. While symbionts associated with low-[Formula: see text] corals receive less total light from the skeleton, they experience a higher rate of light increase once bleaching is initiated and absorbing bodies are lost; further precipitating the bleaching response. Because microscopic skeletal light-scattering is a robust predictor

  10. The Bleaching Syndrome: The Role of Educational Intervention

    Science.gov (United States)

    Hall, Ronald E.

    2016-01-01

    Per the Bleaching Syndrome, people of color, including African, Asian, and Latino Americans, are both victims and perpetrators of color discrimination. The Bleaching Syndrome encompasses perceptual, psychological, and behavioral sectors that affect students' schooling experiences. Education professionals, including teachers, administrators, and…

  11. Biochemical methane potential of kraft bleaching effluent and codigestion with other in-mill streams

    DEFF Research Database (Denmark)

    Fitamo, Temesgen Mathewos; Dahl, Olli; Master, Emma

    2016-01-01

    and in combination: total bleaching effluent, alkaline bleaching effluent, kraft evaporator condensate, and chemithermomechanical pulping effluent. The total bleaching effluent, consisting of the chlorine dioxide bleaching and alkaline bleaching effluents, exhibited the highest potential for organic matter...

  12. [High school student and skin bleaching in Cameroon].

    Science.gov (United States)

    Mayoughouo Mouliom, Adeline; Wamba, André

    2017-04-27

    Introduction: Skin bleaching is a common practice in Africa, particularly in Cameroon. Studies show that it represents a danger for health, in terms of a demonstrated increased risk of dermatological diseases. However, increasing numbers of people are using skin bleaching in African cities, despite the fact that they are sometimes aware of the risk. This study proposed to transform the knowledge and perceptions of skin bleaching practices into educational strategies that can be used both by health professionals and educators. These strategies can also be used as preventive measures against skin bleaching among young schoolgirls. Methods: Data collection was based on a qualitative approach, in the form of a focus group discussion attended by 40 girls aged between 14 and 20 years, selected by convenient random sampling. Results: The results indicated that girls have an approximate knowledge about the consequences of skin bleaching on their health. On the contrary, they have a good knowledge about prevention, which can be used to develop a prevention strategy in order to reduce or eradicate skin bleaching, by educational awareness campaigns Conclusion: These elements can be used as a basis for better prevention and health promotion in schools; so that students adopt healthy behaviours and to prevent those students at risk.

  13. Influence of pH, bleaching agents, and acid etching on surface wear of bovine enamel

    Science.gov (United States)

    Soares, Ana Flávia; Bombonatti, Juliana Fraga Soares; Alencar, Marina Studart; Consolmagno, Elaine Cristina; Honório, Heitor Marques; Mondelli, Rafael Francisco Lia

    2016-01-01

    ABSTRACT Development of new materials for tooth bleaching justifies the need for studies to evaluate the changes in the enamel surface caused by different bleaching protocols. Objective The aim of this study was to evaluate the bovine dental enamel wear in function of different bleaching gel protocols, acid etching and pH variation. Material and Methods Sixty fragments of bovine teeth were cut, obtaining a control and test areas. In the test area, one half received etching followed by a bleaching gel application, and the other half, only the bleaching gel. The fragments were randomly divided into six groups (n=10), each one received one bleaching session with five hydrogen peroxide gel applications of 8 min, activated with hybrid light, diode laser/blue LED (HL) or diode laser/violet LED (VHL) (experimental): Control (C); 35% Total Blanc Office (TBO35HL); 35% Lase Peroxide Sensy (LPS35HL); 25% Lase Peroxide Sensy II (LPS25HL); 15% Lase Peroxide Lite (LPL15HL); and 10% hydrogen peroxide (experimental) (EXP10VHL). pH values were determined by a pHmeter at the initial and final time periods. Specimens were stored, subjected to simulated brushing cycles, and the superficial wear was determined (μm). ANOVA and Tukey´s tests were applied (α=0.05). Results The pH showed a slight decrease, except for Group LPL15HL. Group LPS25HL showed the highest degree of wear, with and without etching. Conclusion There was a decrease from the initial to the final pH. Different bleaching gels were able to increase the surface wear values after simulated brushing. Acid etching before bleaching increased surface wear values in all groups. PMID:27008254

  14. Changes in Caribbean coral disease prevalence after the 2005 bleaching event.

    Science.gov (United States)

    Cróquer, Aldo; Weil, Ernesto

    2009-11-16

    Bleaching events and disease epizootics have increased during the past decades, suggesting a positive link between these 2 causes in producing coral mortality. However, studies to test this hypothesis, integrating a broad range of hierarchical spatial scales from habitats to distant localities, have not been conducted in the Caribbean. In this study, we examined links between bleaching intensity and disease prevalence collected from 6 countries, 2 reef sites for each country, and 3 habitats within each reef site (N = 6 x 2 x 3 = 36 site-habitat combinations) during the peak of bleaching in 2005 and a year after, in 2006. Patterns of disease prevalence and bleaching were significantly correlated (Rho = 0.58, p = 0.04). Higher variability in disease prevalence after bleaching occurred among habitats at each particular reef site, with a significant increase in prevalence recorded in 4 of the 10 site-habitats where bleaching was intense and a non-significant increase in disease prevalence in 18 out of the 26 site-habitats where bleaching was low to moderate. A significant linear correlation was found (r = 0.89, p = 0.008) between bleaching and the prevalence of 2 virulent diseases (yellow band disease and white plague) affecting the Montastraea species complex. Results of this study suggest that if bleaching events become more intense and frequent, disease-related mortality of Caribbean coral reef builders could increase, with uncertain effects on coral reef resilience.

  15. Tooth bleaching using peroxide-containing agents: current status of safety issues.

    Science.gov (United States)

    Li, Y

    1998-08-01

    During the last 10 years, at-home tooth bleaching using peroxide-containing agents has quickly become well accepted. It is one of the most popular cosmetic dental procedures for whitening teeth. Although there are few disputes regarding their efficacy, concerns and debates have continued regarding the safety of peroxide-containing tooth bleaching agents. Potential carcinogenicity and genotoxicity of the peroxides used in bleaching agents are the two most persistent and controversial issues. This article reviews and discusses available information on carcinogenicity and genotoxicity of hydrogen peroxide and the potential risks associated with the use of peroxide-containing bleaching agents. Clinical studies reported after the 1996 international symposium on responses of oral tissues to peroxide-containing bleaching agents are also reviewed. Overall evidence supports the conclusion that the proper use of peroxide-containing at-home tooth bleaching agents is safe. However, potential adverse effects may occur in inappropriate applications, abuses, or the use of inappropriate products. At-home tooth bleaching should be monitored by dental professionals to maximize the benefits while minimizing potential risks.

  16. In situ Effect of Nanohydroxyapatite Paste in Enamel Teeth Bleaching.

    Science.gov (United States)

    Gomes, Yasmin Sb de Lima; Alexandrino, Larissa D; Alencar, Cristiane de M; Alves, Eliane B; Faial, Kelson Cf; Silva, Cecy M

    2017-11-01

    Evaluate in situ the effect of nanohydroxyapatite paste (nano-HAP) before bleaching with hydrogen peroxide 35% (HP35%) by ion chromatography (IC) Knoop hardness number (KHN) and tristimulus colorimetry (TC). A total of 60 fragments were obtained from third molars included (3 mm × 3 mm × 3 mm) and the specimens were divided into three groups (n = 20): Gas chromatography (CG) (negative control group) = no bleaching; HP35% (positive control group) = HP35% whitening (whiteness HP35%); nano-HAP = application for 10 minutes before bleaching treatment + HP35%. The specimens were fixed to the volunteers' molars. The KHN and TC were measured before and after bleaching. For IC, the dentin layer was removed, leaving the enamel that was crushed, and autoclaved for chemical quantification (calcium, fluorine, and phosphorus). The results of KHN and TC were analyzed statistically by analysis of variance (ANOVA) followed by Tukey test (p bleaching treatment. Nano-HA is a biomaterial that has shown positive results in the prevention of deleterious effects on the enamel by the action of the office bleaching treatment.

  17. Effect of bleaching on microhardness of esthetic restorative materials.

    Science.gov (United States)

    Malkondu, Özlem; Yurdagüven, Haktan; Say, Esra Can; Kazazoğlu, Ender; Soyman, Mübin

    2011-01-01

    This study evaluated the effect of a high-concentration carbamide peroxide–containing home bleaching system (Opalescence PF) and a hydrogen peroxide–containing over-the-counter bleaching system (Treswhite Supreme) on the microhardness of two nanocomposites (Filtek Supreme XT and Premise) and leucite-reinforced glass ceramic (Empress Esthetic), glass ceramic (Empress 2 layering), and feldspathic porcelain (Matchmaker MC). A total of 100 specimens, 20 of each kind of the restorative materials, 2 mm in thickness and 10 mm in diameter, were fabricated. Then the specimens were polished with SiC paper and 1 μm alumina polishing paste. After polishing, porcelain specimens were glazed in accordance with the manufacturer's instructions. Each type of restorative material was then randomly divided into two groups (n=10), and the specimens were treated with either Opalescence PF or Treswhite Supreme. The microhardness of the specimens before bleaching (baseline) and after bleaching was determined using a digital microhardness tester. Data were analyzed using the Mann-Whitney U-test and the Wilcoxon test. Opalescence PF significantly influenced the hardness of all the restorative materials. Statistically significant decreases with respect to before bleaching were found for Premise (p=0.005), Empress Esthetic (p=0.003), Empress 2 layering (p=0.005), and Matchmaker-MC (p=0.003), whereas a statistically significant increase was observed in Filtek Supreme XT (p=0.028). The difference in the microhardness values between before and after bleaching using Treswhite Supreme was statistically significant only for Premise (p=0.022). High-concentration carbamide peroxide–containing home bleaching may affect the microhardness of restorative materials.

  18. Treatment of solid non-active wastes

    International Nuclear Information System (INIS)

    Chmielewska, E.

    2008-01-01

    In this part of the text-book treatment of solid non-active wastes is described. This part consist of following chapters: (1) Law on wastes; (2) Present situation in waste management; (3) Strategic tendencies of waste management; (4) Incineration (disposal of solid wastes); (5) Disposal; (6) Composting; (7) Treatment of sludge from sewage clarification plant; (8) Biodegradation; (9) Recycling of wastes (assessing of secondary raw materials). Legal aspects of treatment of solid non-active wastes is presented

  19. Spectrophotometric evaluation of dental bleaching under orthodontic bracket in enamel and dentin

    Science.gov (United States)

    Correr, Americo-Bortolazzo; Rastelli, Alessandra-Nara-Souza; Lima, Débora-Alves-Nunes-Leite; Consani, Rafael-Leonardo-Xediek

    2014-01-01

    Aware of the diffusion capacity of bleaching in the dental tissues, many orthodontists are subjecting their patients to dental bleaching during orthodontic treatment for esthetic purposes or to anticipate the exchange of esthetic restorations after the orthodontic treatment. For this purpose specific products have been developed in pre-loaded whitening trays designed to fit over and around brackets and wires, with clinical efficacy proven. Objective: The objective of this study was to evaluate, through spectrophotometric reflectance, the effectiveness of dental bleaching under orthodontic bracket. Material and Methods: Thirty-two bovine incisors crown blocks of 8 mm x 8 mm height lengths were used. Staining of tooth blocks with black tea was performed for six days. They were distributed randomly into 4 groups (1-home bleaching with bracket, 2- home bleaching without bracket, 3- office bleaching with bracket, 4 office bleaching without bracket). The color evaluation was performed (CIE L * a * b *) using color reflectance spectrophotometer. Metal brackets were bonded in groups 1 and 3. The groups 1 and 2 samples were subjected to the carbamide peroxide at 15%, 4 hours daily for 21 days. Groups 3 and 4 were subjected to 3 in-office bleaching treatment sessions, hydrogen peroxide 38%. After removal of the brackets, the second color evaluation was performed in tooth block, difference between the area under the bracket and around it, and after 7 days to verified color stability. Data analysis was performed using the paired t-test and two-way variance analysis and Tukey’s. Results: The home bleaching technique proved to be more effective compared to the office bleaching. There was a significant difference between the margin and center color values of the specimens that were subjected to bracket bonding. Conclusions: The bracket bond presence affected the effectiveness of both the home and office bleaching treatments. Key words:Tooth bleaching, spectrophotometry

  20. Effects of hydrogen peroxide bleaching strips on tooth surface color, surface microhardness, surface and subsurface ultrastructure, and microchemical (Raman spectroscopic) composition.

    Science.gov (United States)

    Duschner, Heinz; Götz, Hermann; White, Donald J; Kozak, Kathleen M; Zoladz, James R

    2006-01-01

    This study examined the effects of hydrogen peroxide tooth bleaching strips on the surface hardness and morphology of enamel and the ultrastructure and chemical composition of enamel and dentin in vitro. Sound human molars were ground and polished to prepare a uniform substrate for bleaching treatments. A cycling treatment methodology was employed which alternated ex vivo human salivary exposures with bleaching treatments under conditions of controlled temperature and durations of treatment. Bleaching treatments included commercial Crest Whitestrips bleaching strips, which utilize hydrogen peroxide in a gel as the in situ bleaching source at 6.0 and 6.5% concentrations of H2O2. Control treatments included an untreated group. Crest Whitestrips bleaching included treatment exposures simulating 2x the recommended clinical exposures (28 hours bleaching). Surface color measurements were taken prior to and following bleaching to ensure tooth bleaching activity. The effects of bleach on physical properties of enamel were assessed with microhardness measures. Ultrastructural effects were classified by surface and subsurface confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) techniques. In addition, the effects of bleaching on tooth microchemical composition was studied in different tooth regions by coincident assessment of Raman spectroscopic signature. Color assessments confirmed significant ex vivo tooth bleaching by Whitestrips. Surface microhardness and SEM measures revealed no deleterious effects on the enamel surfaces. CLSM micromorphological assessments supported the safety of hydrogen peroxide bleaching strips both on surface and subsurface enamel, DEJ, and dentin ultrastructure. Raman spectroscopy analysis demonstrated no obvious effects of bleaching treatments on the microchemical composition of enamel and dentin. These results confirm that tooth bleaching with hydrogen peroxide whitening strips does not produce changes in surface

  1. Determination of burial dose in incompletely bleached fluvial samples using single grains of quartz

    DEFF Research Database (Denmark)

    Thomsen, Kristina Jørkov; Murray, A.S.; Bøtter-Jensen, Lars

    2007-01-01

    We determine the burial dose in three known-age incompletely bleached fluvial samples using single grains of quartz. Estimation of burial dose in incompletely bleached samples requires that the characteristics of the well-bleached part of the distribution are known in order to distinguish between...... well-bleached and poorly bleached grains. It is especially important to investigate if the uncertainties assigned to individual estimates of dose adequately describe the observed variability in well-bleached dose distributions. We investigate this by quantifying the overdispersion in laboratory-bleached...

  2. Short-term coral bleaching is not recorded by skeletal boron isotopes.

    Science.gov (United States)

    Schoepf, Verena; McCulloch, Malcolm T; Warner, Mark E; Levas, Stephen J; Matsui, Yohei; Aschaffenburg, Matthew D; Grottoli, Andréa G

    2014-01-01

    Coral skeletal boron isotopes have been established as a proxy for seawater pH, yet it remains unclear if and how this proxy is affected by seawater temperature. Specifically, it has never been directly tested whether coral bleaching caused by high water temperatures influences coral boron isotopes. Here we report the results from a controlled bleaching experiment conducted on the Caribbean corals Porites divaricata, Porites astreoides, and Orbicella faveolata. Stable boron (δ11B), carbon (δ13C), oxygen (δ18O) isotopes, Sr/Ca, Mg/Ca, U/Ca, and Ba/Ca ratios, as well as chlorophyll a concentrations and calcification rates were measured on coral skeletal material corresponding to the period during and immediately after the elevated temperature treatment and again after 6 weeks of recovery on the reef. We show that under these conditions, coral bleaching did not affect the boron isotopic signature in any coral species tested, despite significant changes in coral physiology. This contradicts published findings from coral cores, where significant decreases in boron isotopes were interpreted as corresponding to times of known mass bleaching events. In contrast, δ13C and δ18O exhibited major enrichment corresponding to decreases in calcification rates associated with bleaching. Sr/Ca of bleached corals did not consistently record the 1.2°C difference in seawater temperature during the bleaching treatment, or alternatively show a consistent increase due to impaired photosynthesis and calcification. Mg/Ca, U/Ca, and Ba/Ca were affected by coral bleaching in some of the coral species, but the observed patterns could not be satisfactorily explained by temperature dependence or changes in coral physiology. This demonstrates that coral boron isotopes do not record short-term bleaching events, and therefore cannot be used as a proxy for past bleaching events. The robustness of coral boron isotopes to changes in coral physiology, however, suggests that reconstruction of

  3. Mass Coral Bleaching in 2010 in the Southern Caribbean

    OpenAIRE

    Alemu I, Jahson Berhane; Clement, Ysharda

    2014-01-01

    Ocean temperatures are increasing globally and the Caribbean is no exception. An extreme ocean warming event in 2010 placed Tobago's coral reefs under severe stress resulting in widespread coral bleaching and threatening the livelihoods that rely on them. The bleaching response of four reef building taxa was monitored over a six month period across three major reefs systems in Tobago. By identifying taxa resilient to bleaching we propose to assist local coral reef managers in the decision mak...

  4. Influence of thermoluminescence signal for debris flow surface materials by sunlight bleaching

    International Nuclear Information System (INIS)

    Song Bo; Wei Mingjian; He Youbing; Zhou Rui; Zhao Qiuyue; Zhang Bin

    2013-01-01

    Thermoluminescence was utilized for measuring the thermoluminescence signals of the standard debris flow samples which were bleached by simulated sunlight and debris flow samples after real sunlight bleaching. The experiment results demonstrate that light bleaching phenomenon of the debris flow occurs when it experiences a period of exposure. The thermoluminescence signal of the samples weakens gradually with the increase of depth. The optical bleaching phenomenon is obvious. Within a certain depth, light bleaching phenomenon is enhanced with the increase of light intensity. The annealing depth of simulated sunlight bleaching experiment is about 1 mm, and the actual annealing depth of sunlight bleaching is about 6 mm. According to the equivalent dose variation with depth, the mud of natural debris flow can be divided into two stages. It has fundamental significance in the application of thermoluminescence dating techniques to divide the stages of debris flow sediments. (authors)

  5. Trace elementary concentration in enamel after dental bleaching using HI-ERDA

    International Nuclear Information System (INIS)

    Added, N.; Rizzutto, M.A.; Curado, J.F.; Francci, C.; Markarian, R.; Mori, M.

    2006-01-01

    Changes of elementary concentrations in dental enamel after a bleaching treatment with different products, is presented, with special focus on the oxygen contribution. Concentrations for Ca, P, O and C and some other trace elements were obtained for enamel of bovine incisor teeth by HI-ERDA measurements using a 35 Cl incident beam and an ionization chamber. Five groups of teeth with five samples each were treated with a different bleaching agents. Each tooth had its crown sectioned in two halves, one for bleaching test and one the other used as a control. Average values of C/Ca, O/Ca, F/Ca enrichment factors were found. The comparison between bleached and non-bleached halves indicates that bleaching treatment did not affect the mineral structure when low-concentration whitening systems were used. The almost constant oxygen concentration in enamel, suggests little changes due to whitening therapy

  6. Trace elementary concentration in enamel after dental bleaching using HI-ERDA

    Science.gov (United States)

    Added, N.; Rizzutto, M. A.; Curado, J. F.; Francci, C.; Markarian, R.; Mori, M.

    2006-08-01

    Changes of elementary concentrations in dental enamel after a bleaching treatment with different products, is presented, with special focus on the oxygen contribution. Concentrations for Ca, P, O and C and some other trace elements were obtained for enamel of bovine incisor teeth by HI-ERDA measurements using a 35Cl incident beam and an ionization chamber. Five groups of teeth with five samples each were treated with a different bleaching agents. Each tooth had its crown sectioned in two halves, one for bleaching test and one the other used as a control. Average values of C/Ca, O/Ca, F/Ca enrichment factors were found. The comparison between bleached and non-bleached halves indicates that bleaching treatment did not affect the mineral structure when low-concentration whitening systems were used. The almost constant oxygen concentration in enamel, suggests little changes due to whitening therapy.

  7. Trace elementary concentration in enamel after dental bleaching using HI-ERDA

    Energy Technology Data Exchange (ETDEWEB)

    Added, N [GFAA, Depto de Fisica Nuclear, IFUSP, University of Sao Paulo, Travessa R da rua do Matao 187, Cidade Universitaria, Caixa Postal 66318, CEP 05508-970 Sao Paulo, SP (Brazil); Rizzutto, M A [GFAA, Depto de Fisica Nuclear, IFUSP, University of Sao Paulo, Travessa R da rua do Matao 187, Cidade Universitaria, Caixa Postal 66318, CEP 05508-970 Sao Paulo, SP (Brazil); Curado, J F [GFAA, Depto de Fisica Nuclear, IFUSP, University of Sao Paulo, Travessa R da rua do Matao 187, Cidade Universitaria, Caixa Postal 66318, CEP 05508-970 Sao Paulo, SP (Brazil); Francci, C [School of Dentistry, University of Sao Paulo (Brazil); Markarian, R [School of Dentistry, University of Sao Paulo (Brazil); Mori, M [School of Dentistry, University of Sao Paulo (Brazil)

    2006-08-15

    Changes of elementary concentrations in dental enamel after a bleaching treatment with different products, is presented, with special focus on the oxygen contribution. Concentrations for Ca, P, O and C and some other trace elements were obtained for enamel of bovine incisor teeth by HI-ERDA measurements using a {sup 35}Cl incident beam and an ionization chamber. Five groups of teeth with five samples each were treated with a different bleaching agents. Each tooth had its crown sectioned in two halves, one for bleaching test and one the other used as a control. Average values of C/Ca, O/Ca, F/Ca enrichment factors were found. The comparison between bleached and non-bleached halves indicates that bleaching treatment did not affect the mineral structure when low-concentration whitening systems were used. The almost constant oxygen concentration in enamel, suggests little changes due to whitening therapy.

  8. Does the Use of a "Walking Bleaching" Technique Increase Bone Resorption Markers?

    Science.gov (United States)

    Bersezio, C; Vildósola, P; Sáez, M; Sánchez, F; Vernal, R; Oliveira, O B; Jorquera, G; Basualdo, J; Loguercio, A; Fernández, E

    This randomized clinical trial evaluated the effect of 35% hydrogen peroxide in comparison with 37% carbamide peroxide in a nonvital bleaching technique of "walking bleaching" (four sessions of treatment) on periodontal markers: nuclear factor kappa B-ligand (RANK-L-process of root resorption marker) and interleukin 1β (IL-1β-inflammatory response marker). Fifty volunteers presenting with discoloration of nonvital teeth and endodontic treatment in good condition participated. Fifty teeth were randomly divided into two study groups according to bleaching gel: HP = 35% hydrogen peroxide (n=25) and 37% carbamide peroxide (n=25). Nonvital bleaching was performed with a walking bleaching technique consisting of four sessions of bleach application. Gingival crevicular fluid samples were taken in order to quantify the RANK-L and IL-1β levels by enzyme-linked immunosorbent assay. Samples were obtained from six periodontal sites for each bleached tooth: three vestibular and three palatine (mesial, middle, and distal) at seven time periods: baseline, after each of the four sessions of nonvital bleaching, at one week, and at one month after nonvital bleaching. Tooth color variations were analyzed in each session by VITA Bleachedguide 3D-MASTER (ΔSGU). Significant increments in the RANK-L and IL-1β levels were detected in each evaluated time compared with baseline ( pbleaching therapies ( pbleaching induced a significant increment in the RANK-L and IL-1β levels in periodontal tissues around bleached, nonvital teeth.

  9. Unprecedented Mass Bleaching and Loss of Coral across 12° of Latitude in Western Australia in 2010–11

    Science.gov (United States)

    Moore, James A. Y.; Bellchambers, Lynda M.; Depczynski, Martial R.; Evans, Richard D.; Evans, Scott N.; Field, Stuart N.; Friedman, Kim J.; Gilmour, James P.; Holmes, Thomas H.; Middlebrook, Rachael; Radford, Ben T.; Ridgway, Tyrone; Shedrawi, George; Taylor, Heather; Thomson, Damian P.; Wilson, Shaun K.

    2012-01-01

    Background Globally, coral bleaching has been responsible for a significant decline in both coral cover and diversity over the past two decades. During the summer of 2010–11, anomalous large-scale ocean warming induced unprecedented levels of coral bleaching accompanied by substantial storminess across more than 12° of latitude and 1200 kilometers of coastline in Western Australia (WA). Methodology/Principal Findings Extreme La-Niña conditions caused extensive warming of waters and drove considerable storminess and cyclonic activity across WA from October 2010 to May 2011. Satellite-derived sea surface temperature measurements recorded anomalies of up to 5°C above long-term averages. Benthic surveys quantified the extent of bleaching at 10 locations across four regions from tropical to temperate waters. Bleaching was recorded in all locations across regions and ranged between 17% (±5.5) in the temperate Perth region, to 95% (±3.5) in the Exmouth Gulf of the tropical Ningaloo region. Coincident with high levels of bleaching, three cyclones passed in close proximity to study locations around the time of peak temperatures. Follow-up surveys revealed spatial heterogeneity in coral cover change with four of ten locations recording significant loss of coral cover. Relative decreases ranged between 22%–83.9% of total coral cover, with the greatest losses in the Exmouth Gulf. Conclusions/Significance The anomalous thermal stress of 2010–11 induced mass bleaching of corals along central and southern WA coral reefs. Significant coral bleaching was observed at multiple locations across the tropical-temperate divide spanning more than 1200 km of coastline. Resultant spatially patchy loss of coral cover under widespread and high levels of bleaching and cyclonic activity, suggests a degree of resilience for WA coral communities. However, the spatial extent of bleaching casts some doubt over hypotheses suggesting that future impacts to coral reefs under forecast

  10. Value-added products from spent bleaching earth

    International Nuclear Information System (INIS)

    Loh Soh Kheang; Muzammil Ngatiman; James, Stephen

    2010-01-01

    Full text: Bleaching earth is used in the bleaching process of physical refining of palm oil to remove color, phospholipids, residue gums, oxidized products and any trace metals from the oil. These colored pigments are trapped and absorbed in the bleaching earth, thus transforming the originally whitish earth to dark grey and is, from then, named spent bleaching earth (SBE). SBE is considered as an industrial by-product as there is hardly any practical application for it. Large quantity of SBE is commonly disposed of in landfills, which poses potential hazards to environment. New economical ways in utilizing it is sought to eliminate the problem arises from its disposal. This paper presents a study on the possibility of developing a soil conditioner using enhanced SBE as the base material. The study found that there are certain attributes observed in the enhanced SBE that could be of advantages for SBE to become a good soil conditioner. The enhanced SBE contains organic matters and about 18-20 % of residue oil which exhibits good water holding capacity in slow release of water, and enriched nutrient content for plant nutrient uptake. (author)

  11. Variables and potential models for the bleaching of luminescence signals in fluvial environments

    Science.gov (United States)

    Gray, Harrison J.; Mahan, Shannon

    2015-01-01

    Luminescence dating of fluvial sediments rests on the assumption that sufficient sunlight is available to remove a previously obtained signal in a process deemed bleaching. However, luminescence signals obtained from sediment in the active channels of rivers often contain residual signals. This paper explores and attempts to build theoretical models for the bleaching of luminescence signals in fluvial settings. We present two models, one for sediment transported in an episodic manner, such as flood-driven washes in arid environments, and one for sediment transported in a continuous manner, such as in large continental scale rivers. The episodic flow model assumes that the majority of sediment is bleached while exposed to sunlight at the near surface between flood events and predicts a power-law decay in luminescence signal with downstream transport distance. The continuous flow model is developed by combining the Beer–Lambert law for the attenuation of light through a water column with a general-order kinetics equation to produce an equation with the form of a double negative exponential. The inflection point of this equation is compared with the sediment concentration from a Rouse profile to derive a non-dimensional number capable of assessing the likely extent of bleaching for a given set of luminescence and fluvial parameters. Although these models are theoretically based and not yet necessarily applicable to real-world fluvial systems, we introduce these ideas to stimulate discussion and encourage the development of comprehensive bleaching models with predictive power.

  12. Modeling patterns of coral bleaching at a remote Central Pacific atoll.

    Science.gov (United States)

    Williams, Gareth J; Knapp, Ingrid S; Maragos, James E; Davy, Simon K

    2010-09-01

    A mild bleaching event (9.2% prevalence) at Palmyra Atoll occurred in response to the 2009 ENSO, when mean water temperature reached 29.8-30.1 degrees C. Prevalence among both abundant and sparse taxa varied with no clear pattern in susceptibility relating to coral morphology. Seven taxon-specific models showed that turbidity exacerbated while prior exposure to higher background temperatures alleviated bleaching, with these predictors explaining an average 16.3% and 11.5% variation in prevalence patterns, respectively. Positive associations occurred between bleaching prevalence and both immediate temperature during the bleaching event (average 8.4% variation explained) and increased sand cover (average 3.7%). Despite these associations, mean unexplained variation in prevalence equalled 59%. Lower bleaching prevalence in areas experiencing higher background temperatures suggests acclimation to temperature stress among several coral genera, while WWII modifications may still be impacting the reefs via shoreline sediment re-distribution and increased turbidity, exacerbating coral bleaching susceptibility during periods of high temperature stress. Copyright 2010 Elsevier Ltd. All rights reserved.

  13. Coral bleaching pathways under the control of regional temperature variability

    Science.gov (United States)

    Langlais, C. E.; Lenton, A.; Heron, S. F.; Evenhuis, C.; Sen Gupta, A.; Brown, J. N.; Kuchinke, M.

    2017-11-01

    Increasing sea surface temperatures (SSTs) are predicted to adversely impact coral populations worldwide through increasing thermal bleaching events. Future bleaching is unlikely to be spatially uniform. Therefore, understanding what determines regional differences will be critical for adaptation management. Here, using a cumulative heat stress metric, we show that characteristics of regional SST determine the future bleaching risk patterns. Incorporating observed information on SST variability, in assessing future bleaching risk, provides novel options for management strategies. As a consequence, the known biases in climate model variability and the uncertainties in regional warming rate across climate models are less detrimental than previously thought. We also show that the thresholds used to indicate reef viability can strongly influence a decision on what constitutes a potential refugia. Observing and understanding the drivers of regional variability, and the viability limits of coral reefs, is therefore critical for making meaningful projections of coral bleaching risk.

  14. Fracture resistance of teeth submitted to several internal bleaching protocols.

    Science.gov (United States)

    Leonardo, Renato de Toledo; Kuga, Milton Carlos; Guiotti, Flávia Angélica; Andolfatto, Carolina; Faria-Júnior, Norberto Batista de; Campos, Edson Alves de; Keine, Kátia Cristina; Dantas, Andrea Abi Rached

    2014-03-01

    The aim of this study was to evaluate the fracture resistance of teeth submitted to several internal bleaching protocols using 35% hydrogen peroxide (35HP), 37% carbamide peroxide (37CP), 15% hydrogen peroxide with titanium dioxide nanoparticles (15HPTiO2) photoactivated by LED-laser or sodium perborate (SP). After endodontic treatment, fifty bovine extracted teeth were divided into five groups (n = 10): G1-unbleached; G2-35HP; G3-37CP; G4-15HPTiO2 photoactivated by LED-laser and G5-SP. In the G2 and G4, the bleaching protocol was applied in 4 sessions, with 7 days intervals between each session. In the G3 and G5, the materials were kept in the pulp teeth for 21 days, but replaced every 7 days. After 21 days, the teeth were subjected to compressive load at a cross head speed of 0.5 mm/min, applied at 135° to the long axis of the root using an eletromechanical testing machine, until teeth fracture. The data were submitted to ANOVA and Tukey tests (α = 5%). The 35HP, 37CP, 15HPTiO2 and SP showed similar fracture resistance teeth reduction (p > 0.05). All bleaching treatments reduced the fracture resistance compared to unbleached teeth (p endodontically-treated teeth, but there were no differences between each other. There are several internal bleaching protocols using hydrogen peroxide in different concentrations and activation methods. This study evaluated its effects on fracture resistance in endodontically-treated teeth.

  15. Effect of bleaching agent extracts on murine macrophages.

    Science.gov (United States)

    Fernandes, Aletéia M M; Vilela, Polyana G F; Valera, Marcia C; Bolay, Carola; Hiller, Karl Anton; Schweikl, Helmut; Schmalz, Gottfried

    2018-05-01

    The aim of this study was to evaluate the cytotoxicity and the influence of bleaching agents on immunologically cell surface antigens of murine macrophages in vitro. RAW 264.7 cells were exposed to bleaching gel extracts (40% hydrogen peroxide or 20% carbamide peroxide) and different H 2 O 2 concentrations after 1 and 24-h exposure periods and 1-h exposure and 23-h recovery. Tests were performed with and without N-acetyl cysteine (NAC) and buthionine sulfoximine (BSO). Cell viability was determined by MTT assay. The expression of surface markers CD14, CD40, and CD54 with and without LPS stimulation was detected by flow cytometry, while the production of TNF-α was measured by ELISA. Statistical analysis was performed using the Mann-Whitney U test (α = 0.05). Extracts of bleaching agents were cytotoxic for cells after a 1-h exposure; cells could not recover after 24 h. This effect can be mitigated by the antioxidant NAC and increased by BSO, an inhibitor of glutathione (GSH) synthesis. LPS stimulated expression of all surface markers and TNF-α production. Exposure to bleaching agent extracts and H 2 O 2 leads to a reduction of TNF-α, CD14, and CD40 expression, while the expression of CD54 was upregulated at non-cytotoxic concentrations. Whereas NAC reduced this effect, it was increased in the presence of BSO. Extracts of bleaching agents were irreversibly cytotoxic to macrophages after a 1-h exposure. Only the expression of CD54 was upregulated. The reactions are mediated by the non-enzymatic antioxidant GSH. The addition of an antioxidant can downregulate unfavorable effects of dental bleaching.

  16. Thermal bleaching of the V-centres in gamma irradiated KCl:Ca and KCl:Sr crystals

    International Nuclear Information System (INIS)

    Georgiev, G.; Popov, P.; Bakalova, N.

    1982-01-01

    The thermal bleaching of the Vsub(2)sup(M)-and F-bands in gamma irradiated KCl:Ca and KCl:Sr has been investigated under a linear heating with rate of 1 K/min in the temperature range from 270K up to 470K. The results show that during the bleaching the ratio between the concentrations of the F-and Vsub(2)sup(M)-centers is constant. Under the supposition that the ratio is equal to 2, oscillator strenghts of 0.61 and 0.70 have been obtained for the Vsub(2)sup(M)-centre in KCl:Sr, respectively. From the derivatives of the bleaching curves the activation energies and frequency factors for the Vsub(2)sup(M)-centre destruction has been obtained as well. (authors)

  17. Influence of whitening gel on pulp chamber temperature rise by in-office bleaching technique

    Directory of Open Access Journals (Sweden)

    Sandro Cordeiro Loretto

    Full Text Available INTRODUCTION: Dental bleaching is a conservative method for the aesthetic restoration of stained teeth. However, whitening treatments are likely to cause adverse effects when not well planned and executed. OBJECTIVE: This study evaluated the influence of whitening gel on temperature rise in the pulp chamber, using the in-office photoactivated dental bleaching technique. MATERIAL AND METHOD: The root portion of an upper central human incisor was sectioned 3mm below the cemento-enamel junction. The root canal was enlarged to permit the insertion of the K-type thermocouple sensor (MT-401 into the pulp chamber, which was filled with thermal paste to facilitate the transfer of heat during bleaching. Three photosensitive whitening agents (35% hydrogen peroxide were used: Whiteness HP (FGM, Whiteness HP Maxx (FGM and Lase Peroxide Sensy (DMC. An LED photocuring light (Flash Lite - Discus Dental was used to activate the whitening gels. Six bleaching cycles were performed on each group tested. The results were submitted to one-way ANOVA and LSD t-test (α<0.05. RESULT: The lowest mean temperature variation (ºC was detected for Lase Peroxide Sensy (0.20, while the highest was recorded for Whiteness HP (1.50. CONCLUSION: The Whiteness HP and Whiteness HP Maxx whitening gels significantly affected the temperature rise in the pulp chamber during bleaching, and this variation was dependent on the type of whitening gel used.

  18. Low-Activity Radioactive Wastes

    Science.gov (United States)

    In 2003 EPA published an Advance Notice of Proposed Rulemaking (ANPR) to collect public comment on alternatives for disposal of waste containing low concentrations of radioactive material ('low-activity' waste).

  19. Discussion on the origin of bleached sandstone of Qianjiadian uranium deposit

    International Nuclear Information System (INIS)

    Pang Yaqing; Xiang Weidong; Li Tiangang; Chen Xiaolin; Xia Yuliang

    2007-01-01

    Qianjiadian uranium deposit is a sandstone-type uranium deposit that has been discovered in Songliao Basin in recent years. Uranium ore bodies are planar or lenticular in shape and under the control of the contact between gray sandstones and bleached sandstones. The bleached sandstone is white in color, cemented loosely, nearly without TOC and pyrite contained and rich in uranium. Geochemical characteristics and types and assemblages of clay minerals of the bleached sandstone reveal that the bleached sandstone is the product of oxidation of the interlayer oxidation zone, and it is a part of the interlayer oxidation zone. The main reasons for white color of the bleached sandstone are transfer of iron ion, oxidation of TOC and kaolinization of sandstone. (authors)

  20. Efficacy and persistence of tooth bleaching using a diode laser with three different treatment regimens.

    Science.gov (United States)

    Al Quran, Firas A M; Mansour, Yasar; Al-Hyari, Sabaa; Al Wahadni, Ahed; Mair, Lawrence

    2011-01-01

    Studies have measured the effectiveness of tooth bleaching, however there are very few studies that have measured the persistence in color change after a 6-month follow-up. This study assessed the efficacy of the laser bleaching process using different regimens, and the persistence of color change over a 6-month period. Sixty patients divided into three equal groups were subjected to bleaching using a diode laser with 34% hydrogen peroxide. Group 1: patients subjected to one session of laser bleaching. Group 2: patients subjected to two sessions of laser bleaching with a 1-week interval. Group 3: the same as Group 2 but followed by home bleaching once a month for 3 months. The color was assessed four times: before bleaching, directly after bleaching, 3 months after bleaching, and 6 months after bleaching. All teeth had a significant color change at 6 months, but all teeth had regressed from the maximum value. There was significantly less regression in color for Group 3, followed by Groups 2 and 1, respectively. The combined technique of in-office laser bleaching for two sessions with a 1-week interval, followed by home bleaching once a month for 3 months gave more persistence in color change. In-office power bleaching using a laser assisted hydrogen peroxide system repeated after a week, combined with home bleaching once a month for 3 months, is an effective bleaching regimen with less color regression after 6 months compared to a regimen of in-office bleaching alone.

  1. The evaluation of hydrogen peroxide bleaching of Gonometa ...

    African Journals Online (AJOL)

    The effect of hydrogen peroxide bleaching on Gonometa postica silk and the influence that temperature, pH and time duration had on hydrogen peroxide release , colour change, breaking load and stiffness were determined. The best bleaching (81 delta E) of the Gonometa postica silk fabric was obtained with 60 minutes ...

  2. Enamel alteration following tooth bleaching and remineralization

    OpenAIRE

    Coceska, Emilija; Gjorgievska, Elizabeta; Coleman, Nichola; Gabric, Dragana; Slipper, Ian J.; Stevanovic, Marija; Nicholson, John

    2015-01-01

    The purpose of this study was to compare the effects of professional tooth whitening agents containing highly concentrated hydrogen peroxide (with and without laser activation), on the enamel surface; and the potential of four different toothpastes to remineralize any alterations.\\ud \\ud The study was performed on 50 human molars, divided in two groups: treated with Opalescence® Boost and Mirawhite® Laser Bleaching. Furthermore, each group was divided into five subgroups, a control one and 4 ...

  3. Briquette fuel production from wastewater sludge of beer industry and biodiesel production wastes

    Science.gov (United States)

    Nusong, P.; Puajindanetr, S.

    2018-04-01

    The production of industrial wastes is increasing each year. Current methods of waste disposal are severely impacting the environment. Utilization of industrial wastes as an alternative material for fuel is gaining interest due to its environmental friendliness. Thus, the objective of this research was to study the optimum condition for fuel briquettes produced from wastewater sludge of the beer industry and biodiesel production wastes. This research is divided into two parts. Part I will study the effects of carbonization of brewery wastewater sludge for high fixed carbon. Part II will study the ratio between brewery wastewater sludge and bleaching earth for its high heating value. The results show that the maximum fixed carbon of 10.01% by weight was obtained at a temperature of 350 °C for 30 minutes. The appropriate ratio of brewery wastewater sludge and bleaching earth by weight was 95:5. This condition provided the highest heating value of approximately 3548.10 kcal/kg.

  4. Validation of degree heating weeks as a coral bleaching index in the northwestern Pacific

    Science.gov (United States)

    Kayanne, Hajime

    2017-03-01

    Mass bleaching is the most significant threat to coral reefs. The United States National Oceanic and Atmospheric Administration monitors world sea surface temperature (SST) and releases warnings for bleaching based on degree heating weeks (DHW), which is the accumulation of temperature anomalies exceeding the monthly maximum mean SST for a given region. DHW values >4.0 °C-weeks are thought to induce bleaching, and those >8.0 °C-weeks are thought to result in widespread bleaching and some mortality. This study validates the effectiveness of DHW as a mass bleaching index by on-site historical observation at eight sites in the northwestern Pacific Ocean. The mass bleaching events occurred during different years at different sites. The recorded years of the bleaching events matched well with DHW values >8 °C-weeks, and the logistically projected probability of bleaching against DHW showed a positive relationship. DHW provides a reasonable threshold for bleaching.

  5. YouTube as a source of information on skin bleaching: a content analysis.

    Science.gov (United States)

    Basch, C H; Brown, A A; Fullwood, M D; Clark, A; Fung, I C-H; Yin, J

    2018-06-01

    Skin bleaching is a common, yet potentially harmful body modification practice. To describe the characteristics of the most widely viewed YouTube™ videos related to skin bleaching. The search term 'skin bleaching' was used to identify the 100 most popular English-language YouTube videos relating to the topic. Both descriptive and specific information were noted. Among the 100 manually coded skin-bleaching YouTube videos in English, there were 21 consumer-created videos, 45 internet-based news videos, 30 television news videos and 4 professional videos. Excluding the 4 professional videos, we limited our content categorization and regression analysis to 96 videos. Approximately 93% (89/96) of the most widely viewed videos mentioned changing how you look and 74% (71/96) focused on bleaching the whole body. Of the 96 videos, 63 (66%) of videos showed/mentioned a transformation. Only about 14% (13/96) mentioned that skin bleaching is unsafe. The likelihood of a video selling a skin bleaching product was 17 times higher in internet videos compared with consumer videos (OR = 17.00, 95% CI 4.58-63.09, P YouTube video on skin bleaching was uploaded by an internet source. Videos made by television sources mentioned more information about skin bleaching being unsafe, while consumer-generated videos focused more on making skin-bleaching products at home. © 2017 British Association of Dermatologists.

  6. AFM analysis of bleaching effects on dental enamel microtopography

    Energy Technology Data Exchange (ETDEWEB)

    Pedreira de Freitas, Ana Carolina, E-mail: anacarolfreitas@usp.br [Departamento de Dentistica, Faculdade de Odontologia da Universidade de Sao Paulo, Av. Prof. Lineu Prestes, 2227 - Cidade Universitaria, CEP 05508-000, Sao Paulo (Brazil); Cardoso Espejo, Luciana, E-mail: luespejo@hotmail.com [Departamento de Dentistica, Faculdade de Odontologia da Universidade de Sao Paulo, Av. Prof. Lineu Prestes, 2227 - Cidade Universitaria, CEP 05508-000, Sao Paulo (Brazil); Brossi Botta, Sergio, E-mail: sbbotta@usp.br [Departamento de Dentistica, Faculdade de Odontologia da Universidade de Sao Paulo, Av. Prof. Lineu Prestes, 2227 - Cidade Universitaria, CEP 05508-000, Sao Paulo (Brazil); Sa Teixeira, Fernanda de, E-mail: nandast@if.usp.br [Laboratorio de Filmes Finos, Instituto de Fisica da Universidade de Sao Paulo, Rua do Matao, Travessa R, 187 - Cidade Universitaria, CEP 05314-970, Sao Paulo (Brazil); Cerqueira, Luz Maria Aparecida A., E-mail: maacluz@usp.br [Departamento de Dentistica, Faculdade de Odontologia da Universidade de Sao Paulo, Av. Prof. Lineu Prestes, 2227 - Cidade Universitaria, CEP 05508-000, Sao Paulo (Brazil); Garone-Netto, Narciso, E-mail: ngarone@usp.br [Departamento de Dentistica, Faculdade de Odontologia da Universidade de Sao Paulo, Av. Prof. Lineu Prestes, 2227 - Cidade Universitaria, CEP 05508-000, Sao Paulo (Brazil); Bona Matos, Adriana, E-mail: bona@usp.br [Departamento de Dentistica, Faculdade de Odontologia da Universidade de Sao Paulo, Av. Prof. Lineu Prestes, 2227 - Cidade Universitaria, CEP 05508-000, Sao Paulo (Brazil); Barbosa da Silveira Salvadori, Maria Cecilia, E-mail: mcsalva@if.usp.br [Laboratorio de Filmes Finos, Instituto de Fisica da Universidade de Sao Paulo, Rua do Matao, Travessa R, 187 - Cidade Universitaria, CEP 05314-970, Sao Paulo (Brazil)

    2010-02-15

    The purpose of this in vitro study was to test a new methodology to evaluate the effects of 35% hydrogen peroxide agent on the microtopography of sound enamel using an atomic force microscope (AFM). The buccal sound surfaces of three extracted human lower incisors were used, without polishing the surfaces to maintain them with natural morphology. These unpolished surfaces were subjected to bleaching procedure with 35% hydrogen peroxide that consisted of 4 applications of the bleaching agent on enamel surfaces for 10 min each application. Surface images were obtained in a 15 {mu}m x 15 {mu}m area using an AFM. The roughness (Ra and RMS) and the power spectral density (PSD) were obtained before and after the bleaching treatment. As results we could inquire that the PSD analyses were very suitable to identifying the morphological changes on the surfaces, while the Ra and RMS parameters were insufficient to represent the morphological alterations promoted by bleaching procedure on enamel. The morphological wavelength in the range of visible light spectrum (380-750 nm) was analyzed, showing a considerable increase of the PSD with the bleaching treatment.

  7. AFM analysis of bleaching effects on dental enamel microtopography

    International Nuclear Information System (INIS)

    Pedreira de Freitas, Ana Carolina; Cardoso Espejo, Luciana; Brossi Botta, Sergio; Sa Teixeira, Fernanda de; Cerqueira, Luz Maria Aparecida A.; Garone-Netto, Narciso; Bona Matos, Adriana; Barbosa da Silveira Salvadori, Maria Cecilia

    2010-01-01

    The purpose of this in vitro study was to test a new methodology to evaluate the effects of 35% hydrogen peroxide agent on the microtopography of sound enamel using an atomic force microscope (AFM). The buccal sound surfaces of three extracted human lower incisors were used, without polishing the surfaces to maintain them with natural morphology. These unpolished surfaces were subjected to bleaching procedure with 35% hydrogen peroxide that consisted of 4 applications of the bleaching agent on enamel surfaces for 10 min each application. Surface images were obtained in a 15 μm x 15 μm area using an AFM. The roughness (Ra and RMS) and the power spectral density (PSD) were obtained before and after the bleaching treatment. As results we could inquire that the PSD analyses were very suitable to identifying the morphological changes on the surfaces, while the Ra and RMS parameters were insufficient to represent the morphological alterations promoted by bleaching procedure on enamel. The morphological wavelength in the range of visible light spectrum (380-750 nm) was analyzed, showing a considerable increase of the PSD with the bleaching treatment.

  8. Investigating Motivations for Women's Skin Bleaching in Tanzania

    Science.gov (United States)

    Lewis, Kelly M.; Robkin, Navit; Gaska, Karie; Njoki, Lillian Carol

    2011-01-01

    Why do many African women continue to use damaging skin-bleaching cosmetics that contain dangerous chemicals (e.g., mercury) that may increase their rates of infertility, skin cancer, and serious skin/brain/kidney disease? To address this question, our study investigated motivations driving the preservation of skin-bleaching practices in Tanzania.…

  9. In vitro penetration of bleaching agents into the pulp chamber

    DEFF Research Database (Denmark)

    Benetti, Ana Raquel; Valera, M C; Mancini, M N G

    2004-01-01

    To investigate pulp chamber penetration of bleaching agents in teeth following restorative procedures.......To investigate pulp chamber penetration of bleaching agents in teeth following restorative procedures....

  10. BLEACHING EUCALYPTUS PULPS WITH SHORT SEQUENCES

    Directory of Open Access Journals (Sweden)

    Flaviana Reis Milagres

    2011-03-01

    Full Text Available Eucalyptus spp kraft pulp, due to its high content of hexenuronic acids, is quite easy to bleach. Therefore, investigations have been made attempting to decrease the number of stages in the bleaching process in order to minimize capital costs. This study focused on the evaluation of short ECF (Elemental Chlorine Free and TCF (Totally Chlorine Free sequences for bleaching oxygen delignified Eucalyptus spp kraft pulp to 90% ISO brightness: PMoDP (Molybdenum catalyzed acid peroxide, chlorine dioxide and hydrogen peroxide, PMoD/P (Molybdenum catalyzed acid peroxide, chlorine dioxide and hydrogen peroxide, without washing PMoD(PO (Molybdenum catalyzed acid peroxide, chlorine dioxide and pressurized peroxide, D(EPODP (chlorine dioxide, extraction oxidative with oxygen and peroxide, chlorine dioxide and hydrogen peroxide, PMoQ(PO (Molybdenum catalyzed acid peroxide, DTPA and pressurized peroxide, and XPMoQ(PO (Enzyme, molybdenum catalyzed acid peroxide, DTPA and pressurized peroxide. Uncommon pulp treatments, such as molybdenum catalyzed acid peroxide (PMo and xylanase (X bleaching stages, were used. Among the ECF alternatives, the two-stage PMoD/P sequence proved highly cost-effective without affecting pulp quality in relation to the traditional D(EPODP sequence and produced better quality effluent in relation to the reference. However, a four stage sequence, XPMoQ(PO, was required to achieve full brightness using the TCF technology. This sequence was highly cost-effective although it only produced pulp of acceptable quality.

  11. Severity of the 1998 and 2005 bleaching events in Venezuela, southern Caribbean.

    Science.gov (United States)

    Rodríguez, Sebastián; Cróquer, Aldo; Bone, David; Bastidas, Carolina

    2010-10-01

    This study describes the severity of the 2005 bleaching event at 15 reef sites across Venezuela and compares the 1998 and 2005 bleaching events at one of them. During August and September 2005, bleached corals were first observed on oceanic reefs rather than coastal reefs, affecting 1 to 4% of coral colonies in the community (3 reef sites, n = 736 colonies). At that time, however, no bleached corals were recorded along the eastern coast of Venezuela, an area of seasonal upwelling (3 reefs, n = 181 colonies). On coastal reefs, bleaching started in October but highest levels were reached in November 2005 and January 2006, when 16% of corals were affected among a wide range of taxa (e.g. scleractinians, octocorals, Millepora and zoanthids). In the Acropora habitats of Los Roques (an oceanic reef),no bleached was recorded in 2005 (four sites,n = 643 colonies). At Cayo Sombrero, a coastal reef site, bleaching was less severe in 1998 than in 2005 (9% of the coral colonies involving 2 species vs. 26% involving 23 species, respectively). Our results indicate that bleaching was more severe in 2005 than in 1998 on Venezuelan reefs; however, no mass mortality was observed in either of these two events.

  12. Skeletal records of community-level bleaching in Porites corals from Palau

    Science.gov (United States)

    Barkley, Hannah C.; Cohen, Anne L.

    2016-12-01

    Tropical Pacific sea surface temperature is projected to rise an additional 2-3 °C by the end of this century, driving an increase in the frequency and intensity of coral bleaching. With significant global coral reef cover already lost due to bleaching-induced mortality, efforts are underway to identify thermally tolerant coral communities that might survive projected warming. Massive, long-lived corals accrete skeletal bands of anomalously high density in response to episodes of thermal stress. These "stress bands" are potentially valuable proxies for thermal tolerance, but to date their application to questions of community bleaching history has been limited. Ecological surveys recorded bleaching of coral communities across the Palau archipelago during the 1998 and 2010 warm events. Between 2011 and 2015, we extracted skeletal cores from living Porites colonies at 10 sites spanning barrier reef and lagoon environments and quantified the proportion of stress bands present in each population during bleaching years. Across Palau, the prevalence of stress bands tracked the severity of thermal stress, with more stress bands occurring in 1998 (degree heating weeks = 13.57 °C-week) than during the less severe 2010 event (degree heating weeks = 4.86 °C-week). Stress band prevalence also varied by reef type, as more corals on the exposed barrier reef formed stress bands than did corals from sheltered lagoon environments. Comparison of Porites stress band prevalence with bleaching survey data revealed a strong correlation between percent community bleaching and the proportion of colonies with stress bands in each year. Conversely, annual calcification rates did not decline consistently during bleaching years nor did annually resolved calcification histories always track interannual variability in temperature. Our data suggest that stress bands in massive corals contain valuable information about spatial and temporal trends in coral reef bleaching and can aid in

  13. Local bleaching thresholds established by remote sensing techniques vary among reefs with deviating bleaching patterns during the 2012 event in the Arabian/Persian Gulf.

    Science.gov (United States)

    Shuail, Dawood; Wiedenmann, Jörg; D'Angelo, Cecilia; Baird, Andrew H; Pratchett, Morgan S; Riegl, Bernhard; Burt, John A; Petrov, Peter; Amos, Carl

    2016-04-30

    A severe bleaching event affected coral communities off the coast of Abu Dhabi, UAE in August/September, 2012. In Saadiyat and Ras Ghanada reefs ~40% of the corals showed signs of bleaching. In contrast, only 15% of the corals were affected on Delma reef. Bleaching threshold temperatures for these sites were established using remotely sensed sea surface temperature (SST) data recorded by MODIS-Aqua. The calculated threshold temperatures varied between locations (34.48 °C, 34.55 °C, 35.05 °C), resulting in site-specific deviations in the numbers of days during which these thresholds were exceeded. Hence, the less severe bleaching of Delma reef might be explained by the lower relative heat stress experienced by this coral community. However, the dominance of Porites spp. that is associated with the long-term exposure of Delma reef to elevated temperatures, as well as the more pristine setting may have additionally contributed to the higher coral bleaching threshold for this site. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

  14. The very-low activity waste storage facility. A new waste management system

    International Nuclear Information System (INIS)

    2006-01-01

    Very-low activity wastes have a radioactivity level close to the natural one. This category of waste is taken into consideration by the French legislation and their storage is one of their point of achievement. This document gives a complete overview of the principles of storage implemented at the storage center for very-low activity wastes (CSTFA) sited in the Aube departement in the vicinity of the storage center for low- and intermediate activity wastes: storage concept, wastes confinement, center organization, environmental monitoring. (J.S.)

  15. Climate change disables coral bleaching protection on the Great Barrier Reef.

    Science.gov (United States)

    Ainsworth, Tracy D; Heron, Scott F; Ortiz, Juan Carlos; Mumby, Peter J; Grech, Alana; Ogawa, Daisie; Eakin, C Mark; Leggat, William

    2016-04-15

    Coral bleaching events threaten the sustainability of the Great Barrier Reef (GBR). Here we show that bleaching events of the past three decades have been mitigated by induced thermal tolerance of reef-building corals, and this protective mechanism is likely to be lost under near-future climate change scenarios. We show that 75% of past thermal stress events have been characterized by a temperature trajectory that subjects corals to a protective, sub-bleaching stress, before reaching temperatures that cause bleaching. Such conditions confer thermal tolerance, decreasing coral cell mortality and symbiont loss during bleaching by over 50%. We find that near-future increases in local temperature of as little as 0.5°C result in this protective mechanism being lost, which may increase the rate of degradation of the GBR. Copyright © 2016, American Association for the Advancement of Science.

  16. Solid Waste Activity Packet for Teachers.

    Science.gov (United States)

    Illinois Univ., Urbana. Cooperative Extension Service.

    This solid waste activity packet introduces students to the solid waste problem in Illinois. Topics explore consumer practices in the market place, packaging, individual and community garbage generation, and disposal practices. The activities provide an integrated approach to incorporating solid waste management issues into subject areas. The…

  17. Caribbean corals in crisis: record thermal stress, bleaching, and mortality in 2005.

    Science.gov (United States)

    Eakin, C Mark; Morgan, Jessica A; Heron, Scott F; Smith, Tyler B; Liu, Gang; Alvarez-Filip, Lorenzo; Baca, Bart; Bartels, Erich; Bastidas, Carolina; Bouchon, Claude; Brandt, Marilyn; Bruckner, Andrew W; Bunkley-Williams, Lucy; Cameron, Andrew; Causey, Billy D; Chiappone, Mark; Christensen, Tyler R L; Crabbe, M James C; Day, Owen; de la Guardia, Elena; Díaz-Pulido, Guillermo; DiResta, Daniel; Gil-Agudelo, Diego L; Gilliam, David S; Ginsburg, Robert N; Gore, Shannon; Guzmán, Héctor M; Hendee, James C; Hernández-Delgado, Edwin A; Husain, Ellen; Jeffrey, Christopher F G; Jones, Ross J; Jordán-Dahlgren, Eric; Kaufman, Les S; Kline, David I; Kramer, Philip A; Lang, Judith C; Lirman, Diego; Mallela, Jennie; Manfrino, Carrie; Maréchal, Jean-Philippe; Marks, Ken; Mihaly, Jennifer; Miller, W Jeff; Mueller, Erich M; Muller, Erinn M; Orozco Toro, Carlos A; Oxenford, Hazel A; Ponce-Taylor, Daniel; Quinn, Norman; Ritchie, Kim B; Rodríguez, Sebastián; Ramírez, Alberto Rodríguez; Romano, Sandra; Samhouri, Jameal F; Sánchez, Juan A; Schmahl, George P; Shank, Burton V; Skirving, William J; Steiner, Sascha C C; Villamizar, Estrella; Walsh, Sheila M; Walter, Cory; Weil, Ernesto; Williams, Ernest H; Roberson, Kimberly Woody; Yusuf, Yusri

    2010-11-15

    The rising temperature of the world's oceans has become a major threat to coral reefs globally as the severity and frequency of mass coral bleaching and mortality events increase. In 2005, high ocean temperatures in the tropical Atlantic and Caribbean resulted in the most severe bleaching event ever recorded in the basin. Satellite-based tools provided warnings for coral reef managers and scientists, guiding both the timing and location of researchers' field observations as anomalously warm conditions developed and spread across the greater Caribbean region from June to October 2005. Field surveys of bleaching and mortality exceeded prior efforts in detail and extent, and provided a new standard for documenting the effects of bleaching and for testing nowcast and forecast products. Collaborators from 22 countries undertook the most comprehensive documentation of basin-scale bleaching to date and found that over 80% of corals bleached and over 40% died at many sites. The most severe bleaching coincided with waters nearest a western Atlantic warm pool that was centered off the northern end of the Lesser Antilles. Thermal stress during the 2005 event exceeded any observed from the Caribbean in the prior 20 years, and regionally-averaged temperatures were the warmest in over 150 years. Comparison of satellite data against field surveys demonstrated a significant predictive relationship between accumulated heat stress (measured using NOAA Coral Reef Watch's Degree Heating Weeks) and bleaching intensity. This severe, widespread bleaching and mortality will undoubtedly have long-term consequences for reef ecosystems and suggests a troubled future for tropical marine ecosystems under a warming climate.

  18. Influence of Enamel Thickness on Bleaching Efficacy: An In-Depth Color Analysis.

    Science.gov (United States)

    Públio, Juliana do Carmo; D'Arce, Maria Beatriz Freitas; Catelan, Anderson; Ambrosano, Gláucia Maria Bovi; Aguiar, Flávio Henrique Baggio; Lovadino, José Roberto; Lima, Débora Alves Nunes Leite

    2016-01-01

    This study evaluated the influence of different enamel thicknesses and bleaching agents on treatment efficacy in-depth by spectrophotometry color analysis. Eighty bovine dental fragments were previously stained in black tea solution and randomly assigned into eight groups (n=10), 1.75mm dentin thickness and different enamel thicknesses as follows: 0.5mm, 1.0mm planned, 1.0mm unplanned (aprismatic enamel), and absence of enamel. The 10% carbamide peroxide (CP) and 35% hydrogen peroxide (HP) bleaching gels were applied on the enamel surface following the manufacturer's recommendations. Color of underlying dentin was evaluated at four times: after staining with tea (baseline) and after each one of the three weeks of bleaching treatment, by CIE L*a*b* system using reflectance spectrophotometer (CM 700d, Konica Minolta). The ΔE, ΔL, Δa, and Δb values were recorded and subjected to repeated measures ANOVA and Tukey's test (α=0.05). The results showed an increase on lightness (L*), with decreased redness (a*) and yellowness (b*). At first and second week, bleaching with CP showed higher whitening effectiveness compared to bleaching with HP and the presence of aprismatic enamel significantly reduced ΔE for bleaching with CP. After three weeks of bleaching, few differences were observed between CP and HP groups, and outer enamel layer caused no influence on bleaching effectiveness. Overall, both at-home and in-office bleaching treatments were effective and the presence of aprismatic enamel did not interfere on the whitening efficacy.

  19. Effect of three nanobiomaterials on the surface roughness of bleached enamel

    Directory of Open Access Journals (Sweden)

    Maryam Khoroushi

    2015-01-01

    Full Text Available Background: The ever-increasing demand for enhanced esthetic appearance has resulted in significant developments in bleaching products. However, the enamel surface roughness (SR might be negatively affected by bleaching agents. This in vitro study was undertaken to compare the effects of three nanobiomaterials on the enamel SR subsequent to bleaching. Materials and Methods: The crowns of six extracted intact nonerupted human third molars were sectioned. Five dental blocks measuring 2 mm × 3 mm × 4 mm were prepared from each tooth and placed in colorless translucent acrylic resin. The enamel areas from all the specimens were divided into five groups (n = 6: Group 1 did not undergo any bleaching procedures; Group 2 was bleached with a 40% hydrogen peroxide (HP gel; Groups 3, 4, and 5 were bleached with a 40% HP gel modified by bioactive glass (BAG, amorphous calcium phosphate, and hydroxyapatite, respectively. The enamel SR was evaluated before and after treatment by atomic force microscopy. The data were analyzed by Kruskal–Wallis and Mann–Whitney tests. Results: SR increased significantly in the HP group. SR decreased significantly in the HP gel modified by BAG group as compared to other groups. Conclusions: Within the limitations of this study, incorporation of each one of the three test biomaterials proved effective in decreasing enamel SR subsequent to in-office bleaching technique.

  20. Severity of the 1998 and 2005 bleaching events in Venezuela, southern Caribbean

    Directory of Open Access Journals (Sweden)

    Sebastián Rodríguez

    2010-10-01

    Full Text Available This study describes the severity of the 2005 bleaching event at 15 reef sites across Venezuela and compares the 1998 and 2005 bleaching events at one of them. During August and September 2005, bleached corals were first observed on oceanic reefs rather than coastal reefs, affecting 1 to 4% of coral colonies in the community (3 reef sites, n=736 colonies. At that time, however, no bleached corals were recorded along the eastern coast of Venezuela, an area of seasonal upwelling (3 reefs, n=181 colonies. On coastal reefs, bleaching started in October but highest levels were reached in November 2005 and January 2006, when 16% of corals were affected among a wide range of taxa (e.g. scleractinians, octocorals, Millepora and zoanthids. In the Acropora habitats of Los Roques (an oceanic reef, no bleached was recorded in 2005 (four sites, n=643 colonies. At Cayo Sombrero, a coastal reef site, bleaching was less severe in 1998 than in 2005 (9% of the coral colonies involving 2 species vs. 26% involving 23 species, respectively. Our results indicate that bleaching was more severe in 2005 than in 1998 on Venezuelan reefs; however, no mass mortality was observed in either of these two events. Rev. Biol. Trop. 58 (Suppl. 3: 189-196. Epub 2010 October 01.

  1. Bleaching of the thermoluminescence of feldspars by selected wavelengths present in sunlight

    International Nuclear Information System (INIS)

    Robertson, G.B.; Prescott, J.R.; Hutton, J.T.

    1993-01-01

    Feldspars occur in many sediments, and dating them by thermoluminescence (TL) requires a knowledge of how efficiently sunlight bleaches these minerals. The relative bleaching efficiencies of various wavelengths have been investigated for four alkali feldspars and an oligoclase, using the natural TL of the samples and the artificial TL induced by laboratory irradiation, bleached by wavelengths in the range 322-550 nm. Ultraviolet wavelengths are more efficient than the longer wavelengths at bleaching all the glow-curve peaks and are responsible for most of the phototransfer from high-temperature peaks to low-temperature peaks. Some feldspars show an initial increase in TL intensity with bleaching. Two sanidines of similar bulk composition but different TL glow curves show different dependences on bleaching wavelength. In a sodic sanidine with a dominant 240 o C peak the energy required to bleach to 50% was a thousand times greater at 550 nm than at 322 nm. In contrast, another sanidine with a complex glow curve between 150 and 450 o C showed a much slower change in the 330 o C peak with wavelength - a factor of 10 between 322 and 550 nm - with a region between 400 and 500 nm which was almost independent of wavelength. This behaviour is explained by competing mechanisms of phototransfer and bleaching which depend on wavelength in different ways. (author)

  2. Effect of in-office bleaching agents on physical properties of dental composite resins.

    Science.gov (United States)

    Mourouzis, Petros; Koulaouzidou, Elisabeth A; Helvatjoglu-Antoniades, Maria

    2013-04-01

    The physical properties of dental restorative materials have a crucial effect on the longevity of restorations and moreover on the esthetic demands of patients, but they may be compromised by bleaching treatments. The purpose of this study was to evaluate the effects of in-office bleaching agents on the physical properties of three composite resin restorative materials. The bleaching agents used were hydrogen peroxide and carbamide peroxide at high concentrations. Specimens of each material were prepared, cured, and polished. Measurements of color difference, microhardness, and surface roughness were recorded before and after bleaching and data were examined statistically by analysis of variance (ANOVA) and Tukey HSD post-hoc test at P composite resin altered after the bleaching procedure (P composite resins tested (P > .05). The silorane-based composite resin tested showed some color alteration after bleaching procedures. The bleaching procedure did not alter the microhardness and the surface roughness of all composite resins tested.

  3. Analysis of optical bleaching of OSL signal in sediment quartz

    International Nuclear Information System (INIS)

    Przegiętka, K.R.; Chruścińska, A.

    2013-01-01

    The aim of this work was to study the effect of the quality of optical bleaching on the results of OSL (Optically Stimulated Luminescence) dating method. The large aliquots of coarse quartz grains extracted from fluvial deposit were used in the study. The poor, medium and good bleaching were simulated in laboratory with help of Blue LED light source in series of experiments. Then the samples were irradiated with a common laboratory dose. The equivalent doses (DE) were measured by the help of standard Single Aliquot Regeneration (SAR) technique, but obtained DE distributions are analyzed in a new way. The method for recognizing and compensating for partial bleaching is proposed. The conclusions for dating sediment quartz samples are presented and discussed. -- Highlights: ► Bleaching experiments on sediment quartz are performed. ► Blue LED light source incorporated in luminescence reader is used. ► New analysis of data measured by standard SAR OSL technique is proposed. ► The results are promising for recognizing and compensating for partial bleaching

  4. The northern limit of corals of the genus Acropora in temperate zones is determined by their resilience to cold bleaching.

    Science.gov (United States)

    Higuchi, Tomihiko; Agostini, Sylvain; Casareto, Beatriz Estela; Suzuki, Yoshimi; Yuyama, Ikuko

    2015-12-18

    The distribution of corals in Japan covers a wide range of latitudes, encompassing tropical to temperate zones. However, coral communities in temperate zones contain only a small subset of species. Among the parameters that determine the distribution of corals, temperature plays an important role. We tested the resilience to cold stress of three coral species belonging to the genus Acropora in incubation experiments. Acropora pruinosa, which is the northernmost of the three species, bleached at 13 °C, but recovered once temperatures were increased. The two other species, A. hyacinthus and A. solitaryensis, which has a more southerly range than A. pruinosa, died rapidly after bleaching at 13 °C. The physiological effects of cold bleaching on the corals included decreased rates of photosynthesis, respiration, and calcification, similar to the physiological effects observed with bleaching due to high temperature stress. Contrasting hot bleaching, no increases in antioxidant enzyme activities were observed, suggesting that reactive oxygen species play a less important role in bleaching under cold stress. These results confirmed the importance of resilience to cold stress in determining the distribution and northern limits of coral species, as cold events causing coral bleaching and high mortality occur regularly in temperate zones.

  5. Fracture resistance of endodontically-treated teeth: effect of combination bleaching and an antioxidant.

    Science.gov (United States)

    Khoroushi, Maryam; Feiz, Atieh; Khodamoradi, Roghayeh

    2010-01-01

    This in vitro study assessed the fracture resistance of endodontically-treated teeth undergoing combination bleaching with 38% and 9.5% hydrogen peroxide gels as in-office and at-home bleaching techniques, respectively. In addition, the effect of an antioxidizing agent, sodium ascorbate, was investigated. Sixty maxillary premolars were endodontically-treated, received a glass ionomer barrier as a mechanical seal and were embedded in acrylic resin up to the cemento-enamel junction. The specimens were divided into four groups (n = 15) as follows: G I: no bleaching, access cavity restored with resin composite (negative control); G II: bleached for three weeks daily using 9.5% hydrogen peroxide for two hours and three sessions of in-office bleaching using 38% hydrogen peroxide every seven days, then restored (positive control); G III: bleached similar to G II and restored after one week; G IV: bleached similar to G II, along with the use of an antioxidizing agent for 24 hours, then restored. In each in-office and at-home bleaching session, the whitening gels were applied to the buccal surface of the tooth and placed inside the pulp chamber (inside/outside bleaching technique). Finally, the specimens underwent fracture resistance testing; the data were analyzed using ANOVA and Scheffé's test (alpha = 0.05). Significant differences were observed among the study groups (p 0.05). Within the limitations of the current study, it can be concluded that the fracture resistance of endodontically-treated teeth decreases after combination bleaching. The use of sodium ascorbate can reverse decreased fracture resistance.

  6. Catalase characterization and implication in bleaching of a symbiotic sea anemone.

    Science.gov (United States)

    Merle, Pierre-Laurent; Sabourault, Cécile; Richier, Sophie; Allemand, Denis; Furla, Paola

    2007-01-15

    Symbiotic cnidarians are marine invertebrates harboring photosynthesizing microalgae (named zooxanthellae), which produce great amounts of oxygen and free radicals upon illumination. Studying antioxidative balance is then crucial to understanding how symbiotic cnidarians cope with ROS production. In particular, it is suspected that oxidative stress triggers cnidarian bleaching, i.e., the expulsion of zooxanthellae from the animal host, responsible for symbiotic cnidarian mass mortality worldwide. This study therefore investigates catalase antioxidant enzymes and their role in bleaching of the temperate symbiotic sea anemone Anemonia viridis. Using specific separation of animal tissues (ectoderm and endoderm) from the symbionts (zooxanthellae), spectrophotometric assays and native PAGE revealed both tissue-specific and activity pattern distribution of two catalase electrophoretypes, E1 and E2. E1, expressed in all three tissues, presents high sensitivity to the catalase inhibitor aminotriazole (ATZ) and elevated temperatures. The ectodermal E1 form is responsible for 67% of total catalase activity. The E2 form, expressed only within zooxanthellae and their host endodermal cells, displays low sensitivity to ATZ and relative thermostability. We further cloned an ectodermal catalase, which shares 68% identity with mammalian monofunctional catalases. Last, 6 days of exposure of whole sea anemones to ATZ (0.5 mM) led to effective catalase inhibition and initiated symbiont expulsion. This demonstrates the crucial role of this enzyme in cnidarian bleaching, a phenomenon responsible for worldwide climate-change-induced mass mortalities, with catastrophic consequences for marine biodiversity.

  7. Coral bleaching under unconventional scenarios of climate warming and ocean acidification

    Science.gov (United States)

    Kwiatkowski, Lester; Cox, Peter; Halloran, Paul R.; Mumby, Peter J.; Wiltshire, Andy J.

    2015-08-01

    Elevated sea surface temperatures have been shown to cause mass coral bleaching. Widespread bleaching, affecting >90% of global coral reefs and causing coral degradation, has been projected to occur by 2050 under all climate forcing pathways adopted by the IPCC for use within the Fifth Assessment Report. These pathways include an extremely ambitious pathway aimed to limit global mean temperature rise to 2 °C (ref. ; Representative Concentration Pathway 2.6--RCP2.6), which assumes full participation in emissions reductions by all countries, and even the possibility of negative emissions. The conclusions drawn from this body of work, which applied widely used algorithms to estimate coral bleaching, are that we must either accept that the loss of a large percentage of the world’s coral reefs is inevitable, or consider technological solutions to buy those reefs time until atmospheric CO2 concentrations can be reduced. Here we analyse the potential for geoengineering, through stratospheric aerosol-based solar radiation management (SRM), to reduce the extent of global coral bleaching relative to ambitious climate mitigation. Exploring the common criticism of geoengineering--that ocean acidification and its impacts will continue unabated--we focus on the sensitivity of results to the aragonite saturation state dependence of bleaching. We do not, however, address the additional detrimental impacts of ocean acidification on processes such as coral calcification that will further determine the benefit to corals of any SRM-based scenario. Despite the sensitivity of thermal bleaching thresholds to ocean acidification being uncertain, stabilizing radiative forcing at 2020 levels through SRM reduces the risk of global bleaching relative to RCP2.6 under all acidification-bleaching relationships analysed.

  8. Local stressors reduce coral resilience to bleaching.

    Science.gov (United States)

    Carilli, Jessica E; Norris, Richard D; Black, Bryan A; Walsh, Sheila M; McField, Melanie

    2009-07-22

    Coral bleaching, during which corals lose their symbiotic dinoflagellates, typically corresponds with periods of intense heat stress, and appears to be increasing in frequency and geographic extent as the climate warms. A fundamental question in coral reef ecology is whether chronic local stress reduces coral resistance and resilience from episodic stress such as bleaching, or alternatively promotes acclimatization, potentially increasing resistance and resilience. Here we show that following a major bleaching event, Montastraea faveolata coral growth rates at sites with higher local anthropogenic stressors remained suppressed for at least 8 years, while coral growth rates at sites with lower stress recovered in 2-3 years. Instead of promoting acclimatization, our data indicate that background stress reduces coral fitness and resilience to episodic events. We also suggest that reducing chronic stress through local coral reef management efforts may increase coral resilience to global climate change.

  9. On luminescence bleaching of tidal channel sediments

    DEFF Research Database (Denmark)

    Fruergaard, Mikkel; Pejrup, Morten; Murray, Andrew S.

    2015-01-01

    We investigate the processes responsible for bleaching of the quartz OSL signal from tidal channel sediment. Tidal dynamics are expected to play an important role for complete bleaching of tidal sediments. However, no studies have examined the amount of reworking occurring in tidal channels...... and on tidal flats due to the mixing caused by currents and waves. We apply bed level data to evaluate the amount of vertical sediment reworking in modern tidal channels and at a tidal flat. Cycles of deposition and erosion are measured with a bed level sensor, and the results show that gross sedimentation...... was several times higher than net sedimentation. We propose that tidal channel sediment is bleached either on the tidal flat before it is transported to the tidal channels and incorporated in channel-fill successions or, alternatively, on the shallow intertidal part of the channel banks. Based...

  10. Effect of a New Bleaching Gel on Tooth Whitening

    Science.gov (United States)

    2016-05-12

    that claims “wow” results and permanent whiteness unaffected by consumption of coffee, tea, or red wine with low to no sensitivity. KöR has also...tendency for Combined bleaching to result in greater lightness (delta L*) than Home bleaching, suggesting no overall benefit from either technique

  11. Thermal refugia against coral bleaching throughout the northern Red Sea

    KAUST Repository

    Osman, Eslam O.; Smith, David J.; Ziegler, Maren; Kü rten, Benjamin; Conrad, Constanze; El-Haddad, Khaled M.; Voolstra, Christian R.; Suggett, David J.

    2017-01-01

    Tropical reefs have been impacted by thermal anomalies caused by global warming that induced coral bleaching and mortality events globally. However, there have only been very few recordings of bleaching within the Red Sea despite covering a latitudinal range of 15° and consequently it has been considered a region that is less sensitive to thermal anomalies. We therefore examined historical patterns of sea surface temperature (SST) and associated anomalies (1982–2012) and compared warming trends with a unique compilation of corresponding coral bleaching records from throughout the region. These data indicated that the northern Red Sea has not experienced mass bleaching despite intensive Degree Heating Weeks (DHW) of >15°C-weeks. Severe bleaching was restricted to the central and southern Red Sea where DHWs have been more frequent, but far less intense (DHWs <4°C-weeks). A similar pattern was observed during the 2015–2016 El Niño event during which time corals in the northern Red Sea did not bleach despite high thermal stress (i.e. DHWs >8°C-weeks), and bleaching was restricted to the central and southern Red Sea despite the lower thermal stress (DHWs < 8°C-weeks). Heat stress assays carried out in the northern (Hurghada) and central (Thuwal) Red Sea on four key reef-building species confirmed different regional thermal susceptibility, and that central Red Sea corals are more sensitive to thermal anomalies as compared to those from the north. Together, our data demonstrate that corals in the northern Red Sea have a much higher heat tolerance than their prevailing temperature regime would suggest. In contrast, corals from the central Red Sea are close to their thermal limits, which closely match the maximum annual water temperatures. The northern Red Sea harbours reef-building corals that live well below their bleaching thresholds and thus we propose that the region represents a thermal refuge of global importance.

  12. Thermal refugia against coral bleaching throughout the northern Red Sea

    KAUST Repository

    Osman, Eslam O.

    2017-10-17

    Tropical reefs have been impacted by thermal anomalies caused by global warming that induced coral bleaching and mortality events globally. However, there have only been very few recordings of bleaching within the Red Sea despite covering a latitudinal range of 15° and consequently it has been considered a region that is less sensitive to thermal anomalies. We therefore examined historical patterns of sea surface temperature (SST) and associated anomalies (1982–2012) and compared warming trends with a unique compilation of corresponding coral bleaching records from throughout the region. These data indicated that the northern Red Sea has not experienced mass bleaching despite intensive Degree Heating Weeks (DHW) of >15°C-weeks. Severe bleaching was restricted to the central and southern Red Sea where DHWs have been more frequent, but far less intense (DHWs <4°C-weeks). A similar pattern was observed during the 2015–2016 El Niño event during which time corals in the northern Red Sea did not bleach despite high thermal stress (i.e. DHWs >8°C-weeks), and bleaching was restricted to the central and southern Red Sea despite the lower thermal stress (DHWs < 8°C-weeks). Heat stress assays carried out in the northern (Hurghada) and central (Thuwal) Red Sea on four key reef-building species confirmed different regional thermal susceptibility, and that central Red Sea corals are more sensitive to thermal anomalies as compared to those from the north. Together, our data demonstrate that corals in the northern Red Sea have a much higher heat tolerance than their prevailing temperature regime would suggest. In contrast, corals from the central Red Sea are close to their thermal limits, which closely match the maximum annual water temperatures. The northern Red Sea harbours reef-building corals that live well below their bleaching thresholds and thus we propose that the region represents a thermal refuge of global importance.

  13. Bleaching in vital deciduous teeth – a clinical case

    Directory of Open Access Journals (Sweden)

    José Carlos Pettorossi Imparato

    2008-01-01

    Full Text Available There has been growing concern and search for esthetic beauty and harmony over the last few years. This concern does not form part ofadults’ lives only, but also of children’s. Among the substances used for bleaching dental structures, the most outstanding are those whoseactive principle is hydrogen peroxide-based . The present study reports a clinical case of a 4-year-old girl that suffered trauma of tooth 61 with consequent color alteration, but with no alteration in pulp vitality. The main complaint by the patient and her guardians concerned esthetics, therefore external dental bleaching was performed, using Opalescence Xtra® (Ultradent, in two sessions with an interval of one month between them. External in office bleaching was the treatment of choice, due to the tooth vitality, patient’s age and presence of only one darkened tooth. After the bleaching treatments an improvement in the darkening was observed, and both the child and her guardians were satisfied with the esthetic result.

  14. Spatial and temporal patterns of mass bleaching of corals in the Anthropocene

    KAUST Repository

    Hughes, Terry P.

    2018-01-16

    Tropical reef systems are transitioning to a new era in which the interval between recurrent bouts of coral bleaching is too short for a full recovery of mature assemblages. We analyzed bleaching records at 100 globally distributed reef locations from 1980 to 2016. The median return time between pairs of severe bleaching events has diminished steadily since 1980 and is now only 6 years. As global warming has progressed, tropical sea surface temperatures are warmer now during current La Nina conditions than they were during El Nino events three decades ago. Consequently, as we transition to the Anthropocene, coral bleaching is occurring more frequently in all El Nino-Southern Oscillation phases, increasing the likelihood of annual bleaching in the coming decades.

  15. Spatial and temporal patterns of mass bleaching of corals in the Anthropocene

    Science.gov (United States)

    Hughes, Terry P.; Anderson, Kristen D.; Connolly, Sean R.; Heron, Scott F.; Kerry, James T.; Lough, Janice M.; Baird, Andrew H.; Baum, Julia K.; Berumen, Michael L.; Bridge, Tom C.; Claar, Danielle C.; Eakin, C. Mark; Gilmour, James P.; Graham, Nicholas A. J.; Harrison, Hugo; Hobbs, Jean-Paul A.; Hoey, Andrew S.; Hoogenboom, Mia; Lowe, Ryan J.; McCulloch, Malcolm T.; Pandolfi, John M.; Pratchett, Morgan; Schoepf, Verena; Torda, Gergely; Wilson, Shaun K.

    2018-01-01

    Tropical reef systems are transitioning to a new era in which the interval between recurrent bouts of coral bleaching is too short for a full recovery of mature assemblages. We analyzed bleaching records at 100 globally distributed reef locations from 1980 to 2016. The median return time between pairs of severe bleaching events has diminished steadily since 1980 and is now only 6 years. As global warming has progressed, tropical sea surface temperatures are warmer now during current La Niña conditions than they were during El Niño events three decades ago. Consequently, as we transition to the Anthropocene, coral bleaching is occurring more frequently in all El Niño–Southern Oscillation phases, increasing the likelihood of annual bleaching in the coming decades.

  16. Spatial and temporal patterns of mass bleaching of corals in the Anthropocene

    KAUST Repository

    Hughes, Terry P.; Anderson, Kristen D.; Connolly, Sean R.; Heron, Scott F.; Kerry, James T.; Lough, Janice M.; Baird, Andrew H.; Baum, Julia K.; Berumen, Michael L.; Bridge, Tom C.; Claar, Danielle C.; Eakin, C. Mark; Gilmour, James P.; Graham, Nicholas A. J.; Harrison, Hugo; Hobbs, Jean-Paul A.; Hoey, Andrew S.; Hoogenboom, Mia; Lowe, Ryan J.; McCulloch, Malcolm T.; Pandolfi, John M.; Pratchett, Morgan; Schoepf, Verena; Torda, Gergely; Wilson, Shaun K.

    2018-01-01

    Tropical reef systems are transitioning to a new era in which the interval between recurrent bouts of coral bleaching is too short for a full recovery of mature assemblages. We analyzed bleaching records at 100 globally distributed reef locations from 1980 to 2016. The median return time between pairs of severe bleaching events has diminished steadily since 1980 and is now only 6 years. As global warming has progressed, tropical sea surface temperatures are warmer now during current La Nina conditions than they were during El Nino events three decades ago. Consequently, as we transition to the Anthropocene, coral bleaching is occurring more frequently in all El Nino-Southern Oscillation phases, increasing the likelihood of annual bleaching in the coming decades.

  17. Caribbean corals in crisis: record thermal stress, bleaching, and mortality in 2005.

    Directory of Open Access Journals (Sweden)

    C Mark Eakin

    Full Text Available BACKGROUND: The rising temperature of the world's oceans has become a major threat to coral reefs globally as the severity and frequency of mass coral bleaching and mortality events increase. In 2005, high ocean temperatures in the tropical Atlantic and Caribbean resulted in the most severe bleaching event ever recorded in the basin. METHODOLOGY/PRINCIPAL FINDINGS: Satellite-based tools provided warnings for coral reef managers and scientists, guiding both the timing and location of researchers' field observations as anomalously warm conditions developed and spread across the greater Caribbean region from June to October 2005. Field surveys of bleaching and mortality exceeded prior efforts in detail and extent, and provided a new standard for documenting the effects of bleaching and for testing nowcast and forecast products. Collaborators from 22 countries undertook the most comprehensive documentation of basin-scale bleaching to date and found that over 80% of corals bleached and over 40% died at many sites. The most severe bleaching coincided with waters nearest a western Atlantic warm pool that was centered off the northern end of the Lesser Antilles. CONCLUSIONS/SIGNIFICANCE: Thermal stress during the 2005 event exceeded any observed from the Caribbean in the prior 20 years, and regionally-averaged temperatures were the warmest in over 150 years. Comparison of satellite data against field surveys demonstrated a significant predictive relationship between accumulated heat stress (measured using NOAA Coral Reef Watch's Degree Heating Weeks and bleaching intensity. This severe, widespread bleaching and mortality will undoubtedly have long-term consequences for reef ecosystems and suggests a troubled future for tropical marine ecosystems under a warming climate.

  18. Dentin bond strength and nanoleakage of the adhesive interface after intracoronal bleaching.

    Science.gov (United States)

    Cavalli, Vanessa; Sebold, Maicon; Shinohara, Mirela Sanae; Pereira, Patrícia Nóbrega Rodrigues; Giannini, Marcelo

    2018-04-01

    This study evaluated dentin bond strength (BS) and nanoleakage of non- and pre-etched dentin immediately (T 0 ,), 7 days (T 7 ), and 14 days (T 14 ) after bleaching. Bovine incisors (150) were selected and half of them submitted to intrapulpal dentin etching (e). Non- and pre-etched dentin were subjected to the following (n = 15): no bleaching/control (C); 35% carbamide peroxide (CP); 35% hydrogen peroxide (35% HP); 25% hydrogen peroxide (25% HP); and sodium perborate (SP). Bleaching agents were applied to the pulp chamber four times within a 72-h interval. Afterwards, pulp chamber dentin was prepared for the BS test at different evaluation times (n = 5): T 0 , T 7 , and T 14 . Composite blocks were built on pulp chamber and sectioned in slices. Slices were reduced to an hour-glass shape with a cross-sectional area of 0.8 mm 2 and submitted to microtensile BS test. Two additional specimens for each group were prepared for nanoleakage evaluation by transmission electron microscopy (TEM). Results were analyzed by ANOVA (two-way) and Dunnett's test (p bleaching for both sound and pre-etched dentin (p bleached dentin increased for all groups, whereas the pre-etched SPe group presented BS similar to the Ce. Nanoleakage within the hybrid layer was perceptible immediately after bleaching, although a decrease in nanoleakage was observed for all groups at T 14 . Adhesive restorations should be performed 7-14 days after bleaching, according to the bleaching agent used. Intracoronal bleaching should be performed preferably with sodium perborate if previous dentin etching is applied. © 2018 Wiley Periodicals, Inc.

  19. Caribbean Corals in Crisis: Record Thermal Stress, Bleaching, and Mortality in 2005

    Science.gov (United States)

    Eakin, C. Mark; Morgan, Jessica A.; Heron, Scott F.; Smith, Tyler B.; Liu, Gang; Alvarez-Filip, Lorenzo; Baca, Bart; Bartels, Erich; Bastidas, Carolina; Bouchon, Claude; Brandt, Marilyn; Bruckner, Andrew W.; Bunkley-Williams, Lucy; Cameron, Andrew; Causey, Billy D.; Chiappone, Mark; Christensen, Tyler R. L.; Crabbe, M. James C; Day, Owen; de la Guardia, Elena; Díaz-Pulido, Guillermo; DiResta, Daniel; Gil-Agudelo, Diego L.; Gilliam, David S.; Ginsburg, Robert N.; Gore, Shannon; Guzmán, Héctor M.; Hendee, James C.; Hernández-Delgado, Edwin A.; Husain, Ellen; Jeffrey, Christopher F. G.; Jones, Ross J.; Jordán-Dahlgren, Eric; Kaufman, Les S.; Kline, David I.; Kramer, Philip A.; Lang, Judith C.; Lirman, Diego; Mallela, Jennie; Manfrino, Carrie; Maréchal, Jean-Philippe; Marks, Ken; Mihaly, Jennifer; Miller, W. Jeff; Mueller, Erich M.; Muller, Erinn M.; Orozco Toro, Carlos A.; Oxenford, Hazel A.; Ponce-Taylor, Daniel; Quinn, Norman; Ritchie, Kim B.; Rodríguez, Sebastián; Ramírez, Alberto Rodríguez; Romano, Sandra; Samhouri, Jameal F.; Sánchez, Juan A.; Schmahl, George P.; Shank, Burton V.; Skirving, William J.; Steiner, Sascha C. C.; Villamizar, Estrella; Walsh, Sheila M.; Walter, Cory; Weil, Ernesto; Williams, Ernest H.; Roberson, Kimberly Woody; Yusuf, Yusri

    2010-01-01

    Background The rising temperature of the world's oceans has become a major threat to coral reefs globally as the severity and frequency of mass coral bleaching and mortality events increase. In 2005, high ocean temperatures in the tropical Atlantic and Caribbean resulted in the most severe bleaching event ever recorded in the basin. Methodology/Principal Findings Satellite-based tools provided warnings for coral reef managers and scientists, guiding both the timing and location of researchers' field observations as anomalously warm conditions developed and spread across the greater Caribbean region from June to October 2005. Field surveys of bleaching and mortality exceeded prior efforts in detail and extent, and provided a new standard for documenting the effects of bleaching and for testing nowcast and forecast products. Collaborators from 22 countries undertook the most comprehensive documentation of basin-scale bleaching to date and found that over 80% of corals bleached and over 40% died at many sites. The most severe bleaching coincided with waters nearest a western Atlantic warm pool that was centered off the northern end of the Lesser Antilles. Conclusions/Significance Thermal stress during the 2005 event exceeded any observed from the Caribbean in the prior 20 years, and regionally-averaged temperatures were the warmest in over 150 years. Comparison of satellite data against field surveys demonstrated a significant predictive relationship between accumulated heat stress (measured using NOAA Coral Reef Watch's Degree Heating Weeks) and bleaching intensity. This severe, widespread bleaching and mortality will undoubtedly have long-term consequences for reef ecosystems and suggests a troubled future for tropical marine ecosystems under a warming climate. PMID:21125021

  20. Dating implications from solar bleaching of thermoluminescence of ancient marble

    International Nuclear Information System (INIS)

    Liritzis, I.; Galloway, R.B.

    1999-01-01

    Measurements of Thermoluminescence (TL) from Greek marble quarried at Paros, Naxos, Pendeli, Hymitos, Thassos, which have been known since ancient time are presented. The results concern i) the solar bleaching of TL, ii) the solar transmission through marble thicknesses up to 16 mm, and iii) the implications for potential dating of ancient carbed marble monuments/objects. The bleaching rate for marbles is very fast during the first hour of exposure. The solar penetration is at least 35 mm for long exposures. Beyond the 2 mm marble slab for exposure times 90-120 hours of sunshine, the residual bleached TL level is not reached. The bleached TL reaches a plateau which serves as the 'zero time' upon which the archaeological TL dose subsequently builds up and gives the age of a marble monument. (author)

  1. Production of cellulose nanoparticles from blue agave waste treated with environmentally friendly processes.

    Science.gov (United States)

    Robles, Eduardo; Fernández-Rodríguez, Javier; Barbosa, Ananda M; Gordobil, Oihana; Carreño, Neftali L V; Labidi, Jalel

    2018-03-01

    Tequila elaboration leaves two main byproducts that are undervalued (bagasse and leaves). Organosolv pulping and Total Chlorine Free bleaching were integrated to obtain cellulose fibers from agricultural waste which consisted of blue agave bagasse and leaf fibers; together they represent a green process which valorizes biomass waste. The obtained celluloses were characterized by FT-IR, colorimetry, and SEM and their extraction yields were evaluated. These celluloses were used to produce cellulose nanocrystals and cellulose nanofibers. First, an acid hydrolysis was performed in a sonication bath to induce cavitation during the reaction to produce cellulose nanocrystals. Then a high-pressure homogenization was selected to produce cellulose nanofibers. These nanocelluloses were characterized by powder XRD, Nanosizer, zeta potential, NMR, and electronic microscopy. Results showed that cellulose from organosolv pulps bleached with TCF bleaching is suitable for nanocellulose production. Moreover, the use of a new step to separate cellulose nanocrystals resulted in yields almost doubling traditional yields, while the rest of the properties remained within the expected. Copyright © 2018 Elsevier Ltd. All rights reserved.

  2. Association Between In-Office And At-Home Tooth Bleaching: A Single Blind Randomized Clinical Trial.

    Science.gov (United States)

    Rodrigues, João Lima; Rocha, Patrícia Souza; Pardim, Silvia Letícia de Souza; Machado, Ana Cláudia Vieira; Faria-E-Silva, André Luis; Seraidarian, Paulo Isaías

    2018-01-01

    This controlled randomized clinical trial evaluated the effect of associating at-home and in-office bleaching procedures on tooth sensitivity (TS) and bleaching effectiveness. Forty patients subjected to on session of in-office bleaching with 38% peroxide hydrogen. Subsequently, the patients were randomly allocated to receive a second session of in-office bleaching or to use a tray containing 10% carbamide peroxide delivered during 7 consecutive days. The worst TS score reported during or after each bleaching procedure was recorded using a verbal rating scale and TS risk (score different from 0) was calculated. Color changes were measured 7 days after each in-office session (for patients receiving in-office procedures only) or after the end of at-home bleaching (for the combined protocol), and 6 months after the last procedure for both bleaching protocols. Color was assessed by a spectrophotometer and by color match with the Vita Classical and Bleach guide scales. Statistical analyses were carried out to assess possible differences between the protocols regarding the outcomes and to analyze the effect of time of assessment on color changes. The bleaching protocol did not affect the risk for and the maximum level of TS reported, irrespective of the time of assessment. In the color evaluation, the bleaching protocol also did not affect the ultimate tooth color. In conclusion, after one in-office bleaching session, there was no difference in bleaching effectiveness and TS between performing a second in-office session and associating it with 1-week at-home bleaching.

  3. Bacteria are not the primary cause of bleaching in the Mediterranean coral Oculina patagonica.

    Science.gov (United States)

    Ainsworth, T D; Fine, M; Roff, G; Hoegh-Guldberg, O

    2008-01-01

    Coral bleaching occurs when the endosymbiosis between corals and their symbionts disintegrates during stress. Mass coral bleaching events have increased over the past 20 years and are directly correlated with periods of warm sea temperatures. However, some hypotheses have suggested that reef-building corals bleach due to infection by bacterial pathogens. The 'Bacterial Bleaching' hypothesis is based on laboratory studies of the Mediterranean invading coral, Oculina patagonica, and has further generated conclusions such as the coral probiotic hypothesis and coral hologenome theory of evolution. We aimed to investigate the natural microbial ecology of O. patagonica during the annual bleaching using fluorescence in situ hybridization to map bacterial populations within the coral tissue layers, and found that the coral bleaches on the temperate rocky reefs of the Israeli coastline without the presence of Vibrio shiloi or bacterial penetration of its tissue layers. Bacterial communities were found associated with the endolithic layer of bleached coral regions, and a community dominance shift from an apparent cyanobacterial-dominated endolithic layer to an algal-dominated layer was found in bleached coral samples. While bacterial communities certainly play important roles in coral stasis and health, we suggest environmental stressors, such as those documented with reef-building corals, are the primary triggers leading to bleaching of O. patagonica and suggest that bacterial involvement in patterns of bleaching is that of opportunistic colonization.

  4. Effects of a New Bleaching Gel on Tooth Whitening

    Science.gov (United States)

    2016-05-17

    that claims "wow’’ results and permanent whiteness unaffected by consumption of coffee, tea, or red wine with low to no sensitivity. KOR has also...bleaching to result in greater lightness {delta L *)than Home bleaching, suggesting no overall benefit from either technique. Two recent clinical

  5. Environmental Drivers of Variation in Bleaching Severity of Acropora Species during an Extreme Thermal Anomaly

    Directory of Open Access Journals (Sweden)

    Mia O. Hoogenboom

    2017-11-01

    Full Text Available High sea surface temperatures caused global coral bleaching during 2015–2016. During this thermal stress event, we quantified within- and among-species variability in bleaching severity for critical habitat-forming Acropora corals. The objective of this study was to understand the drivers of spatial and species-specific variation in the bleaching susceptibility of these corals, and to evaluate whether bleaching susceptibility under extreme thermal stress was consistent with that observed during less severe bleaching events. We surveyed and mapped Acropora corals at 10 sites (N = 596 around the Lizard Island group on the northern Great Barrier Reef. For each colony, bleaching severity was quantified using a new image analysis technique, and we assessed whether small-scale environmental variables (depth, microhabitat, competition intensity and species traits (colony morphology, colony size, known symbiont clade association explained variation in bleaching. Results showed that during severe thermal stress, bleaching of branching corals was linked to microhabitat features, and was more severe at reef edge compared with lagoonal sites. Bleaching severity worsened over a very short time-frame (~1 week, but did not differ systematically with water depth, competition intensity, or colony size. At our study location, within- and among-species variation in bleaching severity was relatively low compared to the level of variation reported in the literature. More broadly, our results indicate that variability in bleaching susceptibility during extreme thermal stress is not consistent with that observed during previous bleaching events that have ranged in severity among globally dispersed sites, with fewer species escaping bleaching during severe thermal stress. In addition, shaded microhabitats can provide a refuge from bleaching which provides further evidence of the importance of topographic complexity for maintaining the biodiversity and ecosystem

  6. The cumulative impact of annual coral bleaching can turn some coral species winners into losers.

    Science.gov (United States)

    Grottoli, Andréa G; Warner, Mark E; Levas, Stephen J; Aschaffenburg, Matthew D; Schoepf, Verena; McGinley, Michael; Baumann, Justin; Matsui, Yohei

    2014-12-01

    Mass coral bleaching events caused by elevated seawater temperatures result in extensive coral loss throughout the tropics, and are projected to increase in frequency and severity. If bleaching becomes an annual event later in this century, more than 90% of coral reefs worldwide may be at risk of long-term degradation. While corals can recover from single isolated bleaching and can acclimate to recurring bleaching events that are separated by multiple years, it is currently unknown if and how they will survive and possibly acclimatize to annual coral bleaching. Here, we demonstrate for the first time that annual coral bleaching can dramatically alter thermal tolerance in Caribbean corals. We found that high coral energy reserves and changes in the dominant algal endosymbiont type (Symbiodinium spp.) facilitated rapid acclimation in Porites divaricata, whereas low energy reserves and a lack of algal phenotypic plasticity significantly increased susceptibility in Porites astreoides to bleaching the following year. Phenotypic plasticity in the dominant endosymbiont type of Orbicella faveolata did not prevent repeat bleaching, but may have facilitated rapid recovery. Thus, coral holobiont response to an isolated single bleaching event is not an accurate predictor of its response to bleaching the following year. Rather, the cumulative impact of annual coral bleaching can turn some coral species 'winners' into 'losers', and can also facilitate acclimation and turn some coral species 'losers' into 'winners'. Overall, these findings indicate that cumulative impact of annual coral bleaching could result in some species becoming increasingly susceptible to bleaching and face a long-term decline, while phenotypically plastic coral species will acclimatize and persist. Thus, annual coral bleaching and recovery could contribute to the selective loss of coral diversity as well as the overall decline of coral reefs in the Caribbean. © 2014 John Wiley & Sons Ltd.

  7. Spectrophotometric analysis of discoloration and internal bleaching after use of different antibiotic pastes.

    Science.gov (United States)

    Fundaoğlu Küçükekenci, Funda; Çakici, Fatih; Küçükekenci, Ahmet Serkan

    2018-04-14

    To investigate teeth's antibiotic-induced color differences after bleaching using two different techniques. One hundred twenty extracted maxillar human incisors were examined. The specimens were randomly divided into six groups, each receiving one of six antibiotic paste fillings: (1) triple antibiotic paste (TAP) with minocycline, (2) double antibiotic paste (DAP), (3) TAP with amoxicillin, (4) TAP with cefaclor, (5) TAP with doxycycline, and (6) no filling (control group). Spectrophotometric measurements were obtained at baseline and then during the first, second, and third weeks after paste placement. The specimens discolored by antibiotics pastes were randomly divided into two subgroups: (1) internal bleaching with hydrogen peroxide (H 2 O 2) and (2) internal bleaching with H 2 O 2 plus Nd-YAG laser irradiation. The ∆E value was calculated and analyzed using a two-way analysis of variance and post-hoc Tukey's test (α = 0.05). The ∆E for all groups showed color differences exceeding the perceptibility threshold (∆E ˃ 3.7) at all time points except in the control and DAP groups. Minocycline-induced TAP showed the most severe coronal discoloration (32.42). When the ∆E was examined, thermo/photo bleaching (22.01 ± 8.23) caused more bleaching than walking bleaching (19.73 ± 5.73) at every time point (P = 0.19). No group returned to the original color after bleaching (P bleaching with Nd-YAG laser can be useful for bleaching/removing this discoloration. For clinically successful final appearances, understanding the effects of bleaching procedures on antibiotic paste discoloration is important.

  8. Differential Response of Coral Assemblages to Thermal Stress Underscores the Complexity in Predicting Bleaching Susceptibility.

    Science.gov (United States)

    Chou, Loke Ming; Toh, Tai Chong; Toh, Kok Ben; Ng, Chin Soon Lionel; Cabaitan, Patrick; Tun, Karenne; Goh, Eugene; Afiq-Rosli, Lutfi; Taira, Daisuke; Du, Rosa Celia Poquita; Loke, Hai Xin; Khalis, Aizat; Li, Jinghan; Song, Tiancheng

    2016-01-01

    Coral bleaching events have been predicted to occur more frequently in the coming decades with global warming. The susceptibility of corals to bleaching during thermal stress episodes is dependent on many factors and an understanding of these underlying drivers is crucial for conservation management. In 2013, a mild bleaching episode ensued in response to elevated sea temperature on the sediment-burdened reefs in Singapore. Surveys of seven sites highlighted variable bleaching susceptibility among coral genera-Pachyseris and Podabacia were the most impacted (31% of colonies of both genera bleached). The most susceptible genera such as Acropora and Pocillopora, which were expected to bleach, did not. Susceptibility varied between less than 6% and more than 11% of the corals bleached, at four and three sites respectively. Analysis of four of the most bleached genera revealed that a statistical model that included a combination of the factors (genus, colony size and site) provided a better explanation of the observed bleaching patterns than any single factor alone. This underscored the complexity in predicting the coral susceptibility to future thermal stress events and the importance of monitoring coral bleaching episodes to facilitate more effective management of coral reefs under climate change.

  9. Differential Response of Coral Assemblages to Thermal Stress Underscores the Complexity in Predicting Bleaching Susceptibility

    Science.gov (United States)

    Toh, Kok Ben; Ng, Chin Soon Lionel; Cabaitan, Patrick; Tun, Karenne; Goh, Eugene; Afiq-Rosli, Lutfi; Taira, Daisuke; Du, Rosa Celia Poquita; Loke, Hai Xin; Khalis, Aizat; Li, Jinghan; Song, Tiancheng

    2016-01-01

    Coral bleaching events have been predicted to occur more frequently in the coming decades with global warming. The susceptibility of corals to bleaching during thermal stress episodes is dependent on many factors and an understanding of these underlying drivers is crucial for conservation management. In 2013, a mild bleaching episode ensued in response to elevated sea temperature on the sediment-burdened reefs in Singapore. Surveys of seven sites highlighted variable bleaching susceptibility among coral genera–Pachyseris and Podabacia were the most impacted (31% of colonies of both genera bleached). The most susceptible genera such as Acropora and Pocillopora, which were expected to bleach, did not. Susceptibility varied between less than 6% and more than 11% of the corals bleached, at four and three sites respectively. Analysis of four of the most bleached genera revealed that a statistical model that included a combination of the factors (genus, colony size and site) provided a better explanation of the observed bleaching patterns than any single factor alone. This underscored the complexity in predicting the coral susceptibility to future thermal stress events and the importance of monitoring coral bleaching episodes to facilitate more effective management of coral reefs under climate change. PMID:27438593

  10. ENAMEL SUSCEPTIBILITY TO RED WINE STAINING AFTER 35% HYDROGEN PEROXIDE BLEACHING

    Science.gov (United States)

    Berger, Sandrine Bittencourt; Coelho, Alessandra Sanchez; Oliveira, Valéria Aparecida Pessatti; Cavalli, Vanessa; Giannini, Marcelo

    2008-01-01

    Concern has been expressed regarding the staining of enamel surface by different beverages after bleaching. This study investigated the influence of 35% hydrogen peroxide bleaching agents on enamel surface stained with wine after whitening treatments. Flat and polished bovine enamel surfaces were submitted to two commercially available 35% hydrogen peroxide bleaching agents or kept in 100% humidity, as a control group (n = 10). Specimens of all groups were immersed in red wine for 48 h at 37°C, immediately, 24 h or 1 week after treatments. All specimens were ground into powder and prepared for the spectrophotometric analysis. Data were subjected to two-way analysis of variance and Fisher's PLSD test at 5% significance level. The amount of wine pigments uptake by enamel submitted to bleaching treatments was statistically higher than that of control group, independently of the evaluation time. Results suggested that wine staining susceptibility was increased by bleaching treatments. PMID:19089218

  11. Enamel susceptibility to red wine staining after 35% hydrogen peroxide bleaching

    Directory of Open Access Journals (Sweden)

    Sandrine Bittencourt Berger

    2008-06-01

    Full Text Available Concern has been expressed regarding the staining of enamel surface by different beverages after bleaching. This study investigated the influence of 35% hydrogen peroxide bleaching agents on enamel surface stained with wine after whitening treatments. Flat and polished bovine enamel surfaces were submitted to two commercially available 35% hydrogen peroxide bleaching agents or kept in 100% humidity, as a control group (n = 10. Specimens of all groups were immersed in red wine for 48 h at 37°C, immediately, 24 h or 1 week after treatments. All specimens were ground into powder and prepared for the spectrophotometric analysis. Data were subjected to two-way analysis of variance and Fisher's PLSD test at 5% significance level. The amount of wine pigments uptake by enamel submitted to bleaching treatments was statistically higher than that of control group, independently of the evaluation time. Results suggested that wine staining susceptibility was increased by bleaching treatments.

  12. Effects of the bleaching sequence on the optical brighteners action in eucalyptus kraft pulp

    Directory of Open Access Journals (Sweden)

    Mauro Manfredi

    2014-06-01

    Full Text Available During the bleaching process the pulp is treated with chemical reagents that can be retained in the pulp and interfere in the action of the optical brighteners. Different bleaching sequences can produce pulps at the same brightness but with different potential to whiteness increase when treated with optical brighteners. The objective of this study was to evaluate the influence of the bleaching sequence on the efficiency of disulphonated and tetrasulphonated optical brighteners. Eucalyptus kraft pulp was bleached using four different bleaching sequences. For each pulp three brightness targets were aimeds. For each bleaching sequence mathematical model was generated for predicting the final pulp whiteness according to the initial brightness and the optical brightener charge applied. The presence of organochlorine residues in the pulp reduced the effectiveness of the optical brighteners. Therefore, bleaching sequences that use low chlorine dioxide charge favors for greater gains in whiteness with the application of optical brighteners. The replacement of the final chlorine dioxide bleaching stage with a hydrogen peroxide one in the sequence increased the efficiency of the optical brightening agents.

  13. Regulation of apoptotic pathways by Stylophora pistillata (Anthozoa, Pocilloporidae to survive thermal stress and bleaching.

    Directory of Open Access Journals (Sweden)

    Hagit Kvitt

    Full Text Available Elevated seawater temperatures are associated with coral bleaching events and related mortality. Nevertheless, some coral species are able to survive bleaching and recover. The apoptotic responses associated to this ability were studied over 3 years in the coral Stylophora pistillata from the Gulf of Eilat subjected to long term thermal stress. These include caspase activity and the expression profiles of the S. pistillata caspase and Bcl-2 genes (StyCasp and StyBcl-2-like cloned in this study. In corals exposed to thermal stress (32 or 34°C, caspase activity and the expression levels of the StyBcl-2-like gene increased over time (6-48 h and declined to basal levels within 72 h of thermal stress. Distinct transcript levels were obtained for the StyCasp gene, with stimulated expression from 6 to 48 h of 34°C thermal stress, coinciding with the onset of bleaching. Increased cell death was detected in situ only between 6 to 48 h of stress and was limited to the gastroderm. The bleached corals survived up to one month at 32°C, and recovered back symbionts when placed at 24°C. These results point to a two-stage response in corals that withstand thermal stress: (i the onset of apoptosis, accompanied by rapid activation of anti-oxidant/anti-apoptotic mediators that block the progression of apoptosis to other cells and (ii acclimatization of the coral to the chronic thermal stress alongside the completion of symbiosis breakdown. Accordingly, the coral's ability to rapidly curb apoptosis appears to be the most important trait affecting the coral's thermotolerance and survival.

  14. Susceptibility to Coffee Staining during Enamel Remineralization Following the In-Office Bleaching Technique

    DEFF Research Database (Denmark)

    Mori, Aline Akemi; Lima, Fernanda Ferruzzi; Benetti, Ana Raquel

    2016-01-01

    with coffee; (group 2) immersion in a coffee solution for 30 minutes daily for 7 days, starting 1 week after bleaching; and (group 3) immersion in a coffee solution for 30 minutes daily for 14 days, starting immediately after bleaching. Enamel mineralization and color were assessed before bleaching (T1......), immediately after bleaching (T2), and after 7 (T3) and 14 days (T4). The CIE whiteness index (W*) and closeness to white (ΔW*) following bleaching and/or immersion in coffee were calculated. Data were analyzed with Friedman and Wilcoxon tests or Kruskal-Wallis and Mann-Whitney U-tests (α = 0.05). RESULTS...

  15. The bleaching syndrome: manifestation of a post-colonial pathology ...

    African Journals Online (AJOL)

    The post-colonial root of African problems is directly related to skin color. Under the cloak of personal preference, light skin among African women has replaced dark skin as the native ideal. The aftermath is manifestation of the Bleaching Syndrome. Social Work professionals have overlooked the Bleaching Syndrome as ...

  16. The combination of sodium perborate and water as intracoronal teeth bleaching agent

    Directory of Open Access Journals (Sweden)

    Ananta Tantri Budi

    2008-12-01

    Full Text Available Background: The color change on post-endodontic treated teeth can be overcome by intracoronal tooth bleaching using walking bleach. Some agents used in walking bleach are combination of sodium peroxide and hydrogen peroxide, and combination of sodium perborate and water. Purpose: The objective of this review is to provide information and consideration of using safe and effective bleaching agents in the field of dentistry. Reviews: On one side, the use of sodium perborate and water combination does not cause the reduction of dentin hardness, enamel decay, and root resorbtion. On the other side, the use of sodium perborate and 30% hydrogen peroxide combination indicates that it takes longer time in yielding the proper color of teeth. Conclusion: The use of sodium perborate and water combination as bleaching agents is effective and safe.

  17. Seasonal mesophotic coral bleaching of Stylophora pistillata in the Northern Red Sea.

    Science.gov (United States)

    Nir, Orit; Gruber, David F; Shemesh, Eli; Glasser, Eliezra; Tchernov, Dan

    2014-01-01

    Coral bleaching occurs when environmental stress induces breakdown of the coral-algae symbiosis and the host initiates algae expulsion. Two types of coral bleaching had been thoroughly discussed in the scientific literature; the first is primarily associated with mass coral bleaching events; the second is a seasonal loss of algae and/or pigments. Here, we describe a phenomenon that has been witnessed for repeated summers in the mesophotic zone (40-63 m) in the northern Red Sea: seasonal bleaching and recovery of several hermatypic coral species. In this study, we followed the recurring bleaching process of the common coral Stylophora pistillata. Bleaching occurred from April to September with a 66% decline in chlorophyll a concentration, while recovery began in October. Using aquarium and transplantation experiments, we explored environmental factors such as temperature, photon flux density and heterotrophic food availability. Our experiments and observations did not yield one single factor, alone, responsible for the seasonal bleaching. The dinoflagellate symbionts (of the genus Symbiodinium) in shallow (5 m) Stylophora pistillata were found to have a net photosynthetic rate of 56.98-92.19 µmol O2 cm(-2) day(-1). However, those from mesophotic depth (60 m) during months when they are not bleached are net consumers of oxygen having a net photosynthetic rate between -12.86 - (-10.24) µmol O2 cm(-2) day(-1). But during months when these mesophotic corals are partially-bleached, they yielded higher net production, between -2.83-0.76 µmol O2 cm(-2) day(-1). This study opens research questions as to why mesophotic zooxanthellae are more successfully meeting the corals metabolic requirements when Chl a concentration decreases by over 60% during summer and early fall.

  18. Seasonal mesophotic coral bleaching of Stylophora pistillata in the Northern Red Sea.

    Directory of Open Access Journals (Sweden)

    Orit Nir

    Full Text Available Coral bleaching occurs when environmental stress induces breakdown of the coral-algae symbiosis and the host initiates algae expulsion. Two types of coral bleaching had been thoroughly discussed in the scientific literature; the first is primarily associated with mass coral bleaching events; the second is a seasonal loss of algae and/or pigments. Here, we describe a phenomenon that has been witnessed for repeated summers in the mesophotic zone (40-63 m in the northern Red Sea: seasonal bleaching and recovery of several hermatypic coral species. In this study, we followed the recurring bleaching process of the common coral Stylophora pistillata. Bleaching occurred from April to September with a 66% decline in chlorophyll a concentration, while recovery began in October. Using aquarium and transplantation experiments, we explored environmental factors such as temperature, photon flux density and heterotrophic food availability. Our experiments and observations did not yield one single factor, alone, responsible for the seasonal bleaching. The dinoflagellate symbionts (of the genus Symbiodinium in shallow (5 m Stylophora pistillata were found to have a net photosynthetic rate of 56.98-92.19 µmol O2 cm(-2 day(-1. However, those from mesophotic depth (60 m during months when they are not bleached are net consumers of oxygen having a net photosynthetic rate between -12.86 - (-10.24 µmol O2 cm(-2 day(-1. But during months when these mesophotic corals are partially-bleached, they yielded higher net production, between -2.83-0.76 µmol O2 cm(-2 day(-1. This study opens research questions as to why mesophotic zooxanthellae are more successfully meeting the corals metabolic requirements when Chl a concentration decreases by over 60% during summer and early fall.

  19. Improved sensitivity, safety and laboratory turnaround time in the diagnosis of pulmonary tuberculosis by use of bleach sedimentation

    Directory of Open Access Journals (Sweden)

    Ameh James

    2015-11-01

    Full Text Available Background: Inadequate diagnostic processes and human resources in laboratories contribute to a high burden of tuberculosis (TB in low- and middle-income countries. Direct smear microscopy is relied on for TB diagnosis; however, sensitivity rates vary. To improve sensitivity of direct microscopy, the researchers employed several approaches, including sputum digestion and concentration of acid-fast bacilli (AFB, a technique which uses commercial bleach. Objectives: This study compared methods used to diagnose active Mycobacterium tuberculosis infections. Methods: Three sputum specimens were collected from each of 340 participants in Abuja, Nigeria, over two consecutive days. Direct microscopy was performed on all specimens; following microscopy, one specimen from each patient was selected randomly for bleach sedimentation and one for Lowenstein-Jensen culture. Results: Direct microscopy produced 28.8% AFB-positive results, whilst bleach sedimentation resulted in 30.3%. When compared with the cultures, 26.5% were AFB true positive using direct microscopy and 27.1% using bleach sedimentation. Whilst the specificity rate between these two methods was not statistically significant (P = 0.548, the sensitivity rate was significant (P = 0.004. Conclusion: Based on these results, bleach increases the sensitivity of microscopy compared with direct smear and has similar specificity. When diagnosing new cases of pulmonary TB, one bleach-digested smear is as sensitive as three direct smears, reducing waiting times for patients and ensuring the safety of laboratory technicians.

  20. Laser Teeth Bleaching: Evaluation of Eventual Side Effects on Enamel and the Pulp and the Efficiency In Vitro and In Vivo

    Science.gov (United States)

    De Moor, Roeland Jozef Gentil; Meire, Maarten August; De Coster, Peter Jozef

    2015-01-01

    Light and heat increase the reactivity of hydrogen peroxide. There is no evidence that light activation (power bleaching with high-intensity light) results in a more effective bleaching with a longer lasting effect with high concentrated hydrogen peroxide bleaching gels. Laser light differs from conventional light as it requires a laser-target interaction. The interaction takes place in the first instance in the bleaching gel. The second interaction has to be induced in the tooth, more specifically in the dentine. There is evidence that interaction exists with the bleaching gel: photothermal, photocatalytical, and photochemical interactions are described. The reactivity of the gel is increased by adding photocatalyst of photosensitizers. Direct and effective photobleaching, that is, a direct interaction with the colour molecules in the dentine, however, is only possible with the argon (488 and 415 nm) and KTP laser (532 nm). A number of risks have been described such as heat generation. Nd:YAG and especially high power diode lasers present a risk with intrapulpal temperature elevation up to 22°C. Hypersensitivity is regularly encountered, being it of temporary occurrence except for a number of diode wavelengths and the Nd:YAG. The tooth surface remains intact after laser bleaching. At present, KTP laser is the most efficient dental bleaching wavelength. PMID:25874258

  1. Questioning Conventional Wisdom Regarding the Most Suitable Sequence of Enzyme Usage in Pulp Bleaching

    Directory of Open Access Journals (Sweden)

    Avdhesh Kumar Gangwar

    2015-11-01

    Full Text Available Increased public scrutiny and governmental legislation towards the pulp and paper industries have motivated industrialists and researchers to seek improved bleaching sequences having the potential to minimize pollutants in bleach effluent generated during manufacturing of paper. Discovery of toxic chlorinated organics and their components in bleach effluents has focused people’s attention towards finding alternative ways of bleaching pulp. Use of enzymes at industrial scale has become well known, but still it is not clear whether the sequence of enzymatic treatment most often employed in industrial applications represents the best overall practice. The point of enzyme addition is critically important to maximize benefits. Many publications describe the use of an enzyme treatment stage before the use of chemicals in a bleaching process. Insufficient attention has been paid to the alternatives of adding an enzyme in between chemical bleaching agents (intermediate or at the end of the bleaching process.

  2. Bahan pemutih gigi dengan sertifikat ADA/ISO (Tooth bleaching material with ADA/ISO certificate

    Directory of Open Access Journals (Sweden)

    Asti Meizarini

    2005-06-01

    Full Text Available Bleaching of teeth for cosmetic reasons is a popular aspect of cosmetic dentistry because patients realize the aesthetical benefits of these products. The dentist as a clinician's practitioner must be knowledgeable of the products and their application techniques. Bleaching materials which are safe and effective are the ADA accepted or manufactured by those which have already haved ISO certificate. Dentist must have enough knowledge about in-office bleaching prescribed for home-use bleaching including their contra indication and side effects, to advise the patients and provide effective bleaching services.

  3. Influence of bleaching and desensitizing gel on bond strength of orthodontic brackets

    Directory of Open Access Journals (Sweden)

    Fernanda Alves Rodrigues Britto

    2015-04-01

    Full Text Available OBJECTIVE: The objective of this study was to assess, in vitro, the influence of bleaching gel and the use of desensitizing agent over bond strength of ceramic brackets bonded to bovine enamel. METHODS: One hundred bovine incisors were selected and randomly divided into five groups (n = 20: Group 1, control group (without bleaching; Group 2, bleached with 35% hydrogen peroxide; Group 3, bleached with 35% hydrogen peroxide (three applications, 15 minutes each and desensitizing agent applied for 10 minutes; Group 4, bleached with 35% hydrogen peroxide for 40 minutes; Group 5, bleached with 35% hydrogen peroxide for 40 minutes with desensitizing agent applied for 10 minutes. Brackets were bonded 7 days after bleaching and submitted to shear bond strength test after 24 hours at a compression rate of 1 mm/minute. After fracture, the adhesive remnant index (ARI was assessed under stereoscopic at 40 x magnification. Shear strength data (MPa were submitted to one-way ANOVA and Tukey's test with significance level set at 5%. RESULTS: Group 5 (29.33 MPa showed significantly higher bond strength than Group 1 (19.19 MPa, Group 2 (20.59 MPa and Group 4 (23.25 MPa, but with no difference in comparison to Group 3. There was no significant difference among the other groups. The adhesive remnant index showed predominance of score 3, that is, all resin remained adhered to enamel for all groups. CONCLUSION: Bleaching with 35% hydrogen peroxide with calcium associated with desensitizing agent application produced higher bond strength values of brackets bonded to bovine enamel.

  4. Does deposition depth control the OSL bleaching of fluvial sediment?

    NARCIS (Netherlands)

    Cunningham, A. C.; Wallinga, J.; Hobo, N.; Versendaal, A. J.; Makaske, B.; Middelkoop, H.

    2014-01-01

    The Optically Stimulated Luminescence (OSL) signal from fluvial sediment often contains a remnant from the previous deposition cycle, leading to a partially bleached equivalent-dose distribution. Although identification of the burial dose is of primary concern, the degree of bleaching could

  5. Massive bleaching of coral reefs induced by the 2010 ENSO, Puerto Cabello, Venezuela.

    Science.gov (United States)

    del Mónaco, Carlos; Haiek, Gerard; Narciso, Samuel; Galindo, Miguel

    2012-06-01

    El Niño Southern Oscillation (ENSO) has generated global coral massive bleaching. The aim of this work was to evaluate the massive bleaching of coral reefs in Puerto Cabello, Venezuela derived from ENSO 2010. We evaluated the bleaching of reefs at five localities both at three and five meter depth. The coral cover and densities of colonies were estimated. We recorded living coral cover, number and diameter of bleached and non-bleached colonies of each coral species. The colonies were classified according to the proportion of bleached area. Satellite images (Modis Scar) were analyzed for chlorophyll-a concentration and temperature in August, September, October and November from 2008-2010. Precipitation, wind speed and air temperature information was evaluated in meteorological data for 2009 and 2010. A total of 58.3% of colonies, belonging to 11 hexacoral species, were affected and the greatest responses were observed in Colpophyllia natans, Montastraea annularis and Montastraeafaveolata. The most affected localities were closer to the mainland and had a bleached proportion up to 62.73+/-36.55%, with the highest proportion of affected colonies, whereas the farthest locality showed 20.25+/-14.00% bleached and the smallest proportion. The salinity in situ varied between 30 and 33ppm and high levels of turbidity were observed. According to the satellite images, in 2010 the surface water temperature reached 31 degree C in August, September and October, and resulted higher than those registered in 2008 and 2009. Regionally, chlorophyll values were higher in 2010 than in 2008 and 2009. The meteorological data indicated that precipitation in November 2010 was three times higher than in November 2009. Massive coral bleaching occurred due to a three month period of high temperatures followed by one month of intense ENSO-associated precipitation. However, this latter factor was likely the trigger because of the bleaching gradient observed.

  6. Differential Response of Coral Assemblages to Thermal Stress Underscores the Complexity in Predicting Bleaching Susceptibility.

    Directory of Open Access Journals (Sweden)

    Loke Ming Chou

    Full Text Available Coral bleaching events have been predicted to occur more frequently in the coming decades with global warming. The susceptibility of corals to bleaching during thermal stress episodes is dependent on many factors and an understanding of these underlying drivers is crucial for conservation management. In 2013, a mild bleaching episode ensued in response to elevated sea temperature on the sediment-burdened reefs in Singapore. Surveys of seven sites highlighted variable bleaching susceptibility among coral genera-Pachyseris and Podabacia were the most impacted (31% of colonies of both genera bleached. The most susceptible genera such as Acropora and Pocillopora, which were expected to bleach, did not. Susceptibility varied between less than 6% and more than 11% of the corals bleached, at four and three sites respectively. Analysis of four of the most bleached genera revealed that a statistical model that included a combination of the factors (genus, colony size and site provided a better explanation of the observed bleaching patterns than any single factor alone. This underscored the complexity in predicting the coral susceptibility to future thermal stress events and the importance of monitoring coral bleaching episodes to facilitate more effective management of coral reefs under climate change.

  7. Decalcification prevention around orthodontic brackets bonded to bleached enamel using different topical agents.

    Science.gov (United States)

    Msallam, Ferial Ahmed; Grawish, Mohammed El-Awady; Hafez, Ahmad Mohammed; Abdelnaby, Yasser Lotfy

    2017-12-01

    The present study was conducted to evaluate the effect of different topical agents utilized for prevention of enamel decalcification around orthodontic brackets bonded to bleached and non-bleached enamel. Human maxillary premolars (n = 120) were divided into two equal groups. Teeth in group I were left without bleaching while those in group II were bleached with Vivastyle gel. Metal brackets were bonded to all the teeth using light-cured adhesive. Each group was divided into six equal subgroups (A, B, C, D, E, and F). In subgroup A, no material was applied (control). In subgroups B, C, D, E, and F, the following materials were applied respectively: Profluorid varnish, Enamel Pro Varnish, Ortho-Choice Ortho-Coat, GC Tooth Mousse, and GC MI Paste Plus. All teeth were cycled in a demineralization solution/artificial saliva for 15 days. Laser fluorescence was used to measure the level of enamel mineralization. The data were statistically analyzed. Regarding the non-bleaching subgroups, all studied material revealed significant demineralization reduction in comparison to the control subgroup (P  0.05). Ortho-Choice Ortho-Coat, and Profluorid and Enamel Pro varnishes could be utilized successfully to reduce enamel demineralization around brackets bonded to either bleached or non-bleached enamel. GC MI Paste Plus and GC Tooth Mousse were effective only in non-bleached enamel.

  8. Influence of photo- and thermal bleaching on pre-irradiation low water peak single mode fibers

    Science.gov (United States)

    Yin, Jianchong; Wen, Jianxiang; Luo, Wenyun; Xiao, Zhongyin; Chen, Zhenyi; Wang, Tingyun

    2011-12-01

    Reducing the radiation-induced transmission loss in low water peak single mode fiber (LWP SMF) has been investigated by using photo-bleaching method with 980nm pump light source and using thermal-bleaching method with temperature control system. The results show that the radiation-induced loss of pre-irradiation optical fiber can be reduced effectively with the help of photo-bleaching or thermal-bleaching. Although the effort of photo-bleaching is not as significant as thermal-bleaching, by using photo-bleaching method, the loss of fiber caused by radiation-induced defects can be reduced best up to 49% at 1310nm and 28% at 1550nm in low pre-irradiation condition, the coating of the fiber are not destroyed, and the rehabilitating time is just several hours, while self-annealing usually costs months' time. What's more, the typical high power LASER for photo-bleaching can be 980nm pump Laser Diode, which is very accessible.

  9. Effect of fluoride-treated enamel on indirect cytotoxicity of a 16% carbamide peroxide bleaching gel to pulp cells.

    Science.gov (United States)

    Soares, Diana Gabriela; Ribeiro, Ana Paula Dias; Lima, Adriano Fonseca; Sacono, Nancy Tomoko; Hebling, Josimeri; de Souza Costa, Carlos Alberto

    2013-01-01

    The aim of this study was to evaluate the possibility of fluoride solutions applied to enamel to protect pulp cells against the trans-enamel and transdentinal cytotoxicity of a 16% carbamide peroxide (CP) bleaching gel. The CP gel was applied to enamel/dentin discs adapted to aicial pulp chambers (8 h/day) during 1, 7 or 14 days, followed by fluoride (0.05% or 0.2%) application for 1 min. The extracts (culture medium in contact with dentin) were applied to MDPC-23 cells for 1 h, and cell metabolism (MTT assay), alkaline phosphatase (ALP) activity and cell membrane damage (flow cytometry) were analyzed. Knoop microhardness of enamel was also evaluated. Data were analyzed statistically by ANOVA and Kruskal-Wallis tests (α=0.05). For the MTT assay and ALP activity, significant reductions between the control and the bleached groups were observed (p0.05), regardless of fluoride application or treatment days. Flow cytometry analysis demonstrated 30% of cell membrane damage in all bleached groups. After 14 days of treatment, the fluoride-treated enamel presented significantly higher microhardness values than the bleached-only group (pfluoride solutions, the treated enamel surface did not prevent the toxic effects caused by the 16% CP gel to odontoblast-like cells.

  10. The effect of long-term use of tooth bleaching products on the human enamel surface.

    Science.gov (United States)

    Polydorou, Olga; Scheitza, Sophia; Spraul, Mathias; Vach, Kirstin; Hellwig, Elmar

    2018-01-01

    The aim of this in vitro study was to evaluate the long-term effect of bleaching on human enamel. Four groups of enamel specimens were prepared (n = 20): group 1: bleaching with Opalescence Boost [40% hydrogen peroxide (H 2 O 2 ), 3 × 20 min/week]; group 2: control group (the specimens were stored in human saliva); group 3: beaching with Vivastyle Paint on Plus (6% H 2 O 2 , 2 × 10 min/day), and group 4: bleaching with Opalescence PF 16% [16% carbamide peroxide (CP), 6 h/day]. After each bleaching session the specimens were stored in human saliva. Knoop microhardness and surface roughness were measured: before bleaching, after 2-week and after 8-week bleaching. After 2-week treatment, surface roughness was significantly increased in all experimental groups (p  0.05). The roughness changes exerted after 8-week bleaching were not significantly higher than the ones after 2 weeks (p > 0.05). After 8-week treatment, the increase in roughness caused by 16% CP was significantly higher (p bleaching on enamel was not shown to be dependent on the method or the H 2 O 2 concentration. Bleaching with CP 16% resulted in higher roughness than bleaching with H 2 O 2 , while 40% H 2 O 2 caused the higher microhardness increase. The present study showed that in-office bleaching with 40% H 2 O 2 seems to be at least as safe as home bleaching as far as their effects on human enamel are concerned.

  11. OZONE BLEACHING AT NEUTRAL PH – A NEW CONCEPT

    Directory of Open Access Journals (Sweden)

    Fernando de Carvalho

    2010-08-01

    Full Text Available The effect of medium consistency ozone stage pH was evaluated for brown and oxygen delignified eucalyptus kraft pulp samples obtained from VCP - Luiz Antônio pulp mill. These samples were used as such or previously treated with the hot acid stage (A. The main objective of this study was to determine the viability of increasing the ozone stage pH aiming at decreasing bleaching variable costs. The ozone stage was studied in the pH range of 2.5-9.0, taking into account some important variables which affect ozone bleaching: (1 pulp kappa number entering the ozone stage, (2 reactivity of ozone towards lignin versus hexenuronic acids (HexA´s, (3 pulp treatments prior to ozone stage (acid hydrolysis, and (4 pulp treatments after the ozone stage (extraction or a chlorine dioxide stage.  Therefore, the impact of ozone stage pH was investigated in bleaching process such as Z/DEop vs AZ/DEop, Z/DEopD vs AZ/DEopD, Z/E vs AZ/E. The results were interpreted based on ozone stage efficiency and selectivity, and overall bleaching performance measured by the total bleaching chemical consumption required to achieve full brightness, pulp quality and environmental impact. It was concluded that the increase of ozone stage pH from 2.5 to 7.0 has a slightly negative impact on the efficiency and selectivity, measured after Z/DEop sequence, but this effect is not expressive in the end of Z/DEopD bleaching sequence. The increase of ozone stage pH from 2.5 to 7.0 in the sequence Z/DEopD is cost-effective at industrial level because it represents expressive reduction of sulphuric acid and caustic soda demand for pH control in the bleaching plant. These gain areas achieved without any significant changes in pulp quality and effluent load discharge. Nevertheless, the increase of ozone stage pH from 2.5 to 7.0 has a very high negative impact on the efficiency and selectivity for the Z/E and AZ/E processes and it is not recommended in such cases.

  12. Removing polysaccharides-and saccharides-related coloring impurities in alkyl polyglycosides by bleaching with the H2O2/TAED/NaHCO3 system.

    Science.gov (United States)

    Yanmei, Liu; Jinliang, Tao; Jiao, Sun; Wenyi, Chen

    2014-11-04

    The effect of H2O2/TAED/NaHCO3 system, namely NaHCO3 as alkaline agent with the (tetra acetyl ethylene diamine (TAED)) TAED-activated peroxide system, bleaching of alkyl polyglycosides solution was studied by spectrophotometry. The results showed that the optimal bleaching conditions about H2O2/TAED/NaHCO3 system bleaching of alkyl polyglycosides solution were as follows: molar ratio of TAED to H2O2 was 0.06, addition of H2O2 was 8.6%, addition of NaHCO3 was 3.2%, bleaching temperature of 50-65 °C, addition of MgO was 0.13%, and bleaching time was 8h. If too much amount of NaHCO3 was added to the system and maintained alkaline pH, the bleaching effect would be greatly reduced. Fixing molar ratio of TAED to H2O2 and increasing the amount of H2O2 were beneficial to improve the whiteness of alkyl polyglycosides, but adding too much amount of H2O2 would reduce the transparency. In the TAED-activated peroxide system, NaHCO3 as alkaline agent and buffer agent, could overcome the disadvantage of producing black precipitates when NaOH as alkaline agent. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Chlorophyll bleaching by UV-irradiation in vitro and in situ: Absorption and fluorescence studies

    International Nuclear Information System (INIS)

    Zvezdanovic, Jelena; Cvetic, Tijana; Veljovic-Jovanovic, Sonja; Markovic, Dejan

    2009-01-01

    Chlorophyll bleaching by UV-irradiation has been studied by absorbance and fluorescence spectroscopy in extracts containing mixtures of photosynthetic pigments, in acetone and n-hexane solutions, and in aqueous thylakoid suspensions. Chlorophyll undergoes destruction (bleaching) accompanied by fluorescent transient formation obeying first-order kinetics. The bleaching is governed by UV-photon energy input, as well as by different chlorophyll molecular organizations in solvents of different polarities (in vitro), and in thylakoids (in situ). UV-C-induced bleaching of chlorophylls in thylakoids is probably caused by different mechanisms compared to UV-A- and UV-B-induced bleaching

  14. ENSO Weather and Coral Bleaching on the Great Barrier Reef, Australia

    Science.gov (United States)

    McGowan, Hamish; Theobald, Alison

    2017-10-01

    The most devastating mass coral bleaching has occurred during El Niño events, with bleaching reported to be a direct result of increased sea surface temperatures (SSTs). However, El Niño itself does not cause SSTs to rise in all regions that experience bleaching. Nor is the upper ocean warming trend of 0.11°C per decade since 1971, attributed to global warming, sufficient alone to exceed the thermal tolerance of corals. Here we show that weather patterns during El Niño that result in reduced cloud cover, higher than average air temperatures and higher than average atmospheric pressures, play a crucial role in determining the extent and location of coral bleaching on the world's largest coral reef system, the World Heritage Great Barrier Reef (GBR), Australia. Accordingly, synoptic-scale weather patterns and local atmosphere-ocean feedbacks related to El Niño-Southern Oscillation (ENSO) and not large-scale SST warming due to El Niño alone and/or global warming are often the cause of coral bleaching on the GBR.

  15. Influence of Bleaching Agents on Color and Translucency of Aged Resin Composites.

    Science.gov (United States)

    Lago, Maristela; Mozzaquatro, Lisandra R; Rodrigues, Camila; Kaizer, Marina R; Mallmann, André; Jacques, Letícia B

    2017-09-01

    Evaluate the influence of two bleaching agents (16% carbamide peroxide-CP and 35% hydrogen peroxide-HP) on color and translucency of one resin composite (Filtek Z350 XT) in two opacities (enamel and dentin) previously aged in deionized water or red wine. Sixty specimens of each material were divided in two groups (n = 30): aged in water or red wine for 14 days. Then the specimens were divided in three subgroups (n = 10): control/no treatment, treated with 16% carbamide peroxide (Mix Night), treated with 35% hydrogen peroxide (Mix One). Color readings were performed 24 hours after polishing (baseline); after the 14 days of aging; and after bleaching treatment. Color coordinates CIE L*a*b* were measured using a spectrophotometer (SP60 X-Rite). Color change (CIEDE2000) and translucency parameter were calculated. Data were analyzed with repeated measures two-way ANOVA, and Student-Newman-Keuls tests (5%). Bleaching decreased color change in stained resin composites (aged in red wine), whereas increased it in non-stained enamel resin composites (aged in water). CP had better bleaching results with stained resin composites than HP. Translucency of non-stained dentin resin composite decreased with aging, but did not change with bleaching. For stained resin composites, aging caused reduced translucency, whereas bleaching increased it. Effective bleaching of discolored resin composites aged in an acidic and alcoholic media rich in staining agents was achieved, improving color and translucency. Carbamide peroxide showed better performance than hydrogen peroxide for the bleaching of stained resin composites. (J Esthet Restor Dent 29:368-377, 2017). © 2016 Wiley Periodicals, Inc.

  16. The 2014 coral bleaching and freshwater flood events in Kāne'ohe Bay, Hawai'i.

    Science.gov (United States)

    Bahr, Keisha D; Jokiel, Paul L; Rodgers, Kuʻulei S

    2015-01-01

    Until recently, subtropical Hawai'i escaped the major bleaching events that have devastated many tropical regions, but the continued increases in global long-term mean temperatures and the apparent ending of the Pacific Decadal Oscillation (PDO) cool phase have increased the risk of bleaching events. Climate models and observations predict that bleaching in Hawai'i will occur with increasing frequency and increasing severity over future decades. A freshwater "kill" event occurred during July 2014 in the northern part of Kāne'ohe Bay that reduced coral cover by 22.5% in the area directly impacted by flooding. A subsequent major bleaching event during September 2014 caused extensive coral bleaching and mortality throughout the bay and further reduced coral cover in the freshwater kill area by 60.0%. The high temperature bleaching event only caused a 1.0% reduction in live coral throughout the portion of the bay not directly impacted by the freshwater event. Thus, the combined impact of the low salinity event and the thermal bleaching event appears to be more than simply additive. The temperature regime during the September 2014 bleaching event was analogous in duration and intensity to that of the large bleaching event that occurred previously during August 1996, but resulted in a much larger area of bleaching and coral mortality. Apparently seasonal timing as well as duration and magnitude of heating is important. Coral spawning in the dominant coral species occurs early in the summer, so reservoirs of stored lipid in the corals had been depleted by spawning prior to the September 2014 event. Warm months above 27 °C result in lower coral growth and presumably could further decrease lipid reserves, leading to a bleaching event that was more severe than would have happened if the high temperatures occurred earlier in the summer. Hawaiian reef corals decrease skeletal growth at temperatures above 27 °C, so perhaps the "stress period" actually started long before the

  17. Coral bleaching on high-latitude marginal reefs at Sodwana Bay, South Africa

    International Nuclear Information System (INIS)

    Celliers, Louis; Schleyer, Michael H.

    2002-01-01

    Coral bleaching, involving the expulsion of symbiotic zooxanthellae from the host cells, poses a major threat to coral reefs throughout their distributional range. The role of temperature in coral bleaching has been extensively investigated and is widely accepted. A bleaching event was observed on the marginal high-latitude reefs of South Africa located at Sodwana Bay during the summer months of 2000. This was associated with increased sea temperatures with high seasonal peaks in summer and increased radiation in exceptionally clear water. The bleaching was limited to Two-mile Reef and Nine-mile Reef at Sodwana Bay and affected -1 from May 1994 to April 2000. High maximum temperatures were measured (>29 deg. C). The lowest mean monthly and the mean maximum monthly temperatures at which coral bleaching occurred were 27.5 and 28.8 deg. C, respectively, while the duration for which high temperatures occurred in 2000 was 67 days at ≥27.5 deg. C (4 days at ≥28.8 deg. C). Increased water clarity and radiation appeared to be a synergistic cause in the coral bleaching encountered at Sodwana Bay

  18. OSL response bleaching of BeO samples, using fluorescent light and blue LEDs

    International Nuclear Information System (INIS)

    Groppo, Daniela Piai; Caldas, Linda V.E.

    2015-01-01

    The optically stimulated luminescence (OSL) is widely used as a dosimetric technique for many applications. In this work, the OSL response bleaching of BeO samples was studied. The samples were irradiated using a beta radiation source ( 90 Sr+ 90 Y); the bleaching treatments (fluorescent light and blue LEDs) were performed, and the results were compared. Various optical treatment time intervals were tested until reaching the complete bleaching of the OSL response. The best combination of the time interval and bleaching type was analyzed. (author)

  19. OSL response bleaching of BeO samples, using fluorescent light and blue LEDs

    International Nuclear Information System (INIS)

    Groppo, D P; Caldas, L V E

    2016-01-01

    The optically stimulated luminescence (OSL) is widely used as a dosimetric technique for many applications. In this work, the OSL response bleaching of BeO samples was studied. The samples were irradiated using a beta radiation source ("9"0Sr+"9"0Y); the bleaching treatments (fluorescent light and blue LEDs) were performed, and the results were compared. Various optical treatment time intervals were tested until reaching the complete bleaching of the OSL response. The best combination of the time interval and bleaching type was analyzed. (paper)

  20. Effect of two bleaching agents on enamel morphology: a SEM study

    Directory of Open Access Journals (Sweden)

    Ghavam M.

    2005-05-01

    Full Text Available Statement of Problem: Bleaching materials are able to change the surface morphology as well as mineral and organic content of tooth structure. Considering that bleaching is done for aesthetic purpose, awareness of the possible effect of these materials on hard tissue is important, because it may affect the restorative treatments. Purpose: The aim of this study was comparing the effect of two bleaching materials, Kimia and Ultradent both containing 35% H2O2, on tooth enamel by SEM. Materials and Methods: Five intact central incisors were cut into three sections vertically and each part was randomly divided into three groups. Group 1 (control, without any bleaching. Group 2, bleached with Kimia 35% H2O2. Group 3, bleached with Ultradent 35% H2O2. Each tooth served as its own control. Then the samples were observed by SEM with 250 and 500 magnifications. Results: In the control group some scratches and small white grains were observed which seems to be the result of mastication trauma and pumice powder. In the other groups, morphologic changes like increased surface roughness, deepening of cracks, rod exposure and presence of new cracks were observed. The two experimental materials did not differ in these regards. Conclusion: It seems that both studied materials have limited destructive effects on tooth enamel which seems to be of no clinical importance.

  1. Assessing Coral Response to a Severe Bleaching Event Using Mulimolecular Biomarkers

    Science.gov (United States)

    Babcock-Adams, L.; Minarro, S.; Fitt, W. K.; Medeiros, P. M.

    2016-02-01

    Coral bleaching events occur primarily due to increased seawater temperatures that results in the expulsion and/or reduction of endosymbiotic zooxanthellae. The Adaptive Bleaching Hypothesis suggests that bleaching events allow a different symbiont to populate the host. Specifically, the Symbiodinium clade D has been shown to increase in abundance following a bleaching event. Approximately 40 coral tissue samples (Orbicella annularis and Orbicella faveolata) were collected in the Florida Keys in March, May, August, and November of 2000, and analyzed using GC-MS for molecular biomarkers to determine if a different suite of compounds is produced at different times following the severe bleaching events in 1997 and 1998, and to relate the biomarker composition and levels to the symbiont(s) that were present in the corals. Our preliminary results show a predominant presence of saccharides (e.g., glucose, sucrose) and sterols (e.g., cholesterol, campesterol, brassicasterol), and to a lesser degree saturated (C16:0, C18:0, C20:0) and unsaturated fatty acids (C16:1; C18:1; C18:2; C20:4). The corals with the bleaching resistant clade D symbiont have higher levels of sterols as compared to corals with other non-resistant symbionts that were collected at the same time point. Concentrations of both sterols and saccharides increased throughout time, especially from March to May, which may indicate a recovery of the corals.

  2. Hydroquinone neuropathy following use of skin bleaching creams: case report.

    Science.gov (United States)

    Karamagi, C; Owino, E; Katabira, E T

    2001-04-01

    A 30-year old black woman presented with gradual onset of weakness of the legs associated with burning sensation in the feet for two months. She had been using two hydroquinone based skin bleaching creams (MGC by M. G. C. International, MEKAKO by Anglo Fabrics BOLTON Ltd) for about four years. Her BP was 80/40 mm Hg supine with un-recordable diastolic pressure on standing. She had decreased power (Grade 3/5), loss of deep tendon reflexes and impairment of deep sensation in the lower limbs. A complete blood count, urinalysis, serum electrolytes, serum creatinine and uric acid were all normal. Oral GTT, VDRL and brucella tests were negative. Chest and abdominal radiographs did not show any abnormalities. A diagnosis of peripheral neuropathy with autonomic neuropathy possibly due to hydroquinone toxicity was made and she was advised to stop using hydroquinone based skin bleaching creams. Four months later she was asymptomatic, her BP was 120/80 mmHg supine and standing, and neurological examination was normal. The case raises the question of whether hydroquinone based skin bleaching creams could be a cause of peripheral neuropathy and underscores the need for research on hydroquinone based skin bleaching creams and neuropathy particularly in black women involved in the sale and/or use of skin bleaching creams.

  3. Shear bond strength after dentin bleaching with 10% carbamide peroxide agents

    OpenAIRE

    Basting, Roberta Tarkany; Freitas, Patrícia Moreira de; Pimenta, Luiz André Freire; Serra, Mônica Campos

    2004-01-01

    This in vitro study evaluated the shear bond strength (SBS) of dentin treated with two 10% carbamide peroxide bleaching agents 15 days after bleaching and storage in artificial saliva. Dentin fragments were randomly divided into 3 groups (n = 20) for the treatment with the two different bleaching agents (Rembrandt 10% or Opalescence 10%) or with a placebo agent, applied to the tooth surface for 8 hours a day. During the remaining time, the specimens were stored in artificial saliva. After 42 ...

  4. [Effect of bleaching agents on the color of indirect and direct composite resins].

    Science.gov (United States)

    Xing, Wenzhong; Jiang, Tao; Chen, Xiaodong; Wang, Yining

    2014-09-01

    To evaluate the effect of bleaching agents on the color of indirect and direct composite resins. Five resin composite materials were tested in this in vitro study. The five composites were as follow: two indirect composite resins (Adoro SR, Ceramage) and three direct composite resins (Filtek Z350, Clearfil Majesty Esthetic, and Gradia Direct Anterior). For each material, twenty disk-shaped specimens were prepared and randomly divided into five groups according to the color parameters of specimens before bleaching treatment. The composite resin specimens were treated by one of five sample solutions which were at-home bleaching agents (10% and 15% carbarmide peroxide), in- office bleaching agents (38% H(2)O(2) and 35%H(2)O(2)) and deionized water (control group). The color parameters of specimens were measured by spectrophotometer at baseline and after bleaching treatments. The color differences (ΔE values) between baseline and post-treatments were calculated. The data of color differences were evaluated statistically using two-way analysis with a significance level of 0.05. The color changes of the resin composites were less than 2.0 after bleaching agent treatment, therefore were not perceptible. Slight increase of L(*) values and decrease of C(*)ab values in color parameters of specimens were observed. There were statistically significant differences in ΔE values for different bleaching treatments and resin materials (P = 0.001). The bleaching agents did not affect the color of indirect and direct composite resins tested.

  5. Bleaching response of coral species in the context of assemblage response

    Science.gov (United States)

    Swain, Timothy D.; DuBois, Emily; Goldberg, Scott J.; Backman, Vadim; Marcelino, Luisa A.

    2017-06-01

    Caribbean coral reefs are declining due to a mosaic of local and global stresses, including climate change-induced thermal stress. Species and assemblage responses differ due to factors that are not easily identifiable or quantifiable. We calculated a novel species-specific metric of coral bleaching response, taxon- α and - β, which relates the response of a species to that of its assemblages for 16 species over 18 assemblages. By contextualizing species responses within the response of their assemblages, the effects of environmental factors are removed and intrinsic differences among taxa are revealed. Most corals experience either a saturation response, overly sensitive to weak stress ( α > 0) but under-responsive compared to assemblage bleaching ( β bleaching ( β > 1). This metric may help reveal key factors of bleaching susceptibility and identify species as targets for conservation.

  6. Through bleaching and tsunami: Coral reef recovery in the Maldives.

    Science.gov (United States)

    Morri, Carla; Montefalcone, Monica; Lasagna, Roberta; Gatti, Giulia; Rovere, Alessio; Parravicini, Valeriano; Baldelli, Giuseppe; Colantoni, Paolo; Bianchi, Carlo Nike

    2015-09-15

    Coral reefs are degrading worldwide, but little information exists on their previous conditions for most regions of the world. Since 1989, we have been studying the Maldives, collecting data before, during and after the bleaching and mass mortality event of 1998. As early as 1999, many newly settled colonies were recorded. Recruits shifted from a dominance of massive and encrusting corals in the early stages of recolonisation towards a dominance of Acropora and Pocillopora by 2009. Coral cover, which dropped to less than 10% after the bleaching, returned to pre-bleaching values of around 50% by 2013. The 2004 tsunami had comparatively little effect. In 2014, the coral community was similar to that existing before the bleaching. According to descriptors and metrics adopted, recovery of Maldivian coral reefs took between 6 and 15years, or may even be considered unachieved, as there are species that had not come back yet. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. The Stability of the Giant Clam Holobiont over Time and during Bleaching Stress

    KAUST Repository

    Pappas, Melissa

    2017-01-01

    Experimental bleaching shows that Red Sea giant clams, although exposed to rather hot temperatures naturally, will bleach at 34°C after two weeks, and severely bleached clams likely will not recover. During bleaching, Symbiodinium types shift as well, and shift more drastically than seasonal shifts during the year. This shifting may be an evolved characteristic of the giant clam to aid in surviving major changes in the environment. However, more research is needed to determine if these holobionts are capable of keeping up with the global forecast of warming in reef environments.

  8. Graded changes in enamel component volumes resulted from a short tooth bleaching procedure.

    Science.gov (United States)

    Ferreira, Artemisa Fernanda Moura; Perez, Flávia Maria de Moraes Ramos; Limeira Júnior, Francisco de Assis; de Moura, Mirella de Fátima Liberato; de Sousa, Frederico Barbosa

    2016-05-01

    To test the hypothesis that changes in enamel component volumes (mineral, organic, and water volumes, and permeability) are graded from outer to inner enamel after a short bleaching procedure. Extracted unerupted human third molars had half of their crowns bleached (single bleaching session, 3 × 15 min), and tooth shade changes in bleached parts were analyzed with a spectrophotometer. Ground sections were prepared, component volumes and permeability were quantified at histological points located at varying distances from the enamel surface (n=10 points/location), representing conditions before and after bleaching. Tooth shade changes were significant (pbleaching, except at the outer layers. Multiple analysis of covariances revealed that most of the variance of the change in enamel composition after bleaching was explained by the combination of the set of types of component volume (in decreasing order of relevance: mineral loss, organic gain, water gain, and decrease in permeability) with the set of distances from the enamel surface (graded from the enamel surface inward) (canonical R(2)=0.97; p99%). Changes in enamel composition after a short bleaching procedure followed a gradient within component volumes (mineral loss>organic gain>water gain>decrease in permeability) and decreased from the enamel surface inward. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Effect of newer antioxidants on the bond strength of composite on bleached enamel

    Directory of Open Access Journals (Sweden)

    M Manoharan

    2016-01-01

    Full Text Available Aim: The study aims to evaluate the effect of the application of two antioxidants on the bond strength of composite resin to bleached enamel. Materials and Methods: Eighty enamel surfaces were obtained from forty human extracted premolars. Specimens were randomly divided into four groups (n = 20. Group 1: No bleaching (control; Group 2a: Bleaching with 15% carbamide peroxide gel; Group 2b: Bleaching, followed by application of 10% sodium ascorbate gel; Group 2c: Bleaching, followed by application of 5% proanthocyanidin agent. Surfaces were etched followed by application of total etch bonding system, and composite resin cylinders were bonded. Specimens were tested for shear bond strength. Statistical Analysis Used: One-way analysis of variance was used for multiple group comparison and post hoc Tukey′s test for individual group-wise comparison. Results: Significantly higher shear bond strength values were observed in Group 2c and 2b as compared with Group 1 and 2a (P < 0.05. Among the antioxidants, Group 2c showed significantly higher shear bond strength values than Group 2b (P < 0.05. Conclusion: It can be concluded that the use of antioxidant before bonding procedures on bleached enamel completely neutralizes the deleterious effects of bleaching and increases the bond strength significantly.

  10. Effect of Different Bleaching Techniques on Microleakage under orthodontic Brackets: In Vitro Study

    Directory of Open Access Journals (Sweden)

    Salehi P

    2018-03-01

    Full Text Available Statement of problem: Numerous studies report significant changes in tooth color that occur during orthodontic treatment. The adverse effects of bleaching procedures during orthodontic treatments have not been studied comprehensively. Objectives: This study investigated the effects of two methods of dental bleaching on the degree of microleakage beneath orthodontic brackets. Materials and Methods: We selected 45 extracted premolar teeth and bonded them to orthodontic brackets. These teeth were stored in normal saline for 24 hours and thermocycled. We randomly divided the samples into 3 groups of 15 teeth per group. The first group (control received no bleach treatment; the second group (office bleaching was treated with 35% hydrogen peroxide (Whiteness HP Maxx; and the third group (home bleaching was treated with 22% carbamide peroxide (Whiteness Perfect. The apices were sealed with sticky wax, rinsed in tap water, and air-dried. We applied nail varnish to the entire surface of each tooth, except for an area approximately 1 mm away from the brackets. The samples were immersed in basic fuchsine and cleaned after 24 hours. Microleakage was determined by direct measurement using a stereomicroscope. Kruskal-Wallis and Dunn post-hoc statistical tests, and SPSS software were used for statistical analysis. The significance level was set at P≤0.05. Results: The office bleaching group had significantly more microleakage scores under the brackets at both the occlusal (P=0.04 and gingival (P =0.040 margins of the brackets compared to the home bleaching group. The home bleaching group showed statistically more significant microleakage scores than the control group in both the gingival (P=0.006 and occlusal (P=0.014 margins of the brackets. All three groups had statistically more significant microleakage at the gingival margins of the brackets than the occlusal margins. Conclusions: Office bleaching caused the most microleakage under the brackets and home

  11. Effect of antioxidant agents on bond strength of composite to bleached enamel with 38% hydrogen peroxide

    Directory of Open Access Journals (Sweden)

    Juliane Marcela Guimaraes da Silva

    2011-01-01

    Full Text Available This study evaluated the effect of antioxidant agents on microtensile bond strengths (mTBS of composite to bleached enamel. Fifteen freshly extracted human third molars were selected and randomly assigned to 6 groups (n = 5: (NB enamel not bleached, (B bleached enamel, (BR7 bleached enamel and restored 7 days later, (BSA bleached enamel+sodium ascorbate, (BMC bleached enamel+malvidin chloride, (BPC bleached enamel+pelargonidin chloride. The groups were bleached with 38% hydrogen peroxide (HP - Opalescence Xtra Boost and restored with Single Bond+Filtek Z350. The specimens were thermocycled and submitted to a microtensile load at 1 mm/min crosshead speed. The data were evaluated by ANOVA and Tukey test at 5% of significance. The mean and standard-deviation for all groups were: NB: 30.95(±11.97a; BSA: 30.34(±8.73a, BPC: 22.81(6.00b, BR7: 21.41(±6.12b, B: 14.10(±4.45c, BMC: 13.25(±6.02c. Sodium ascorbate reversed the bond strengths to enamel immediately after bleaching.

  12. Toothpaste use protocol with dental bleaching for a conservative treatment: Case reports

    Directory of Open Access Journals (Sweden)

    Waldemir F. Vieira-Junior

    2017-01-01

    Full Text Available In-office bleaching is a treatment based on products that contain hydrogen peroxide (HP while demonstrating whitening effectiveness. HP could promote alterations to surface morphologies and properties of dental tissues. The objective was describe a toothpaste protocol associated to bleaching therapy to promote a safer approach. Patient 1 (male and Patient 2 (female were attended, and toothbrushing (twice a day with a dentifrice containing bioactive glass (BG (NovaMin™ and fluoride was indicated before and during the treatment. Three bleaching sessions were made in cases, at intervals of 7 days. The gels used were 35% HP (Patient 1 and 35% HP supplied with calcium (Patient 2. The effectiveness of bleaching treatment was observed in both cases (Vita scale, with an esthetic self-acceptance. Sensitivity associated with the procedure was not reported. The indication of BG-based toothpaste is relevant in relation to enamel properties and did not affect the whitening effectiveness of dental bleaching.

  13. SECONDARY WASTE MANAGEMENT STRATEGY FOR EARLY LOW ACTIVITY WASTE TREATMENT

    Energy Technology Data Exchange (ETDEWEB)

    TW, CRAWFORD

    2008-07-17

    This study evaluates parameters relevant to River Protection Project secondary waste streams generated during Early Low Activity Waste operations and recommends a strategy for secondary waste management that considers groundwater impact, cost, and programmatic risk. The recommended strategy for managing River Protection Project secondary waste is focused on improvements in the Effiuent Treatment Facility. Baseline plans to build a Solidification Treatment Unit adjacent to Effluent Treatment Facility should be enhanced to improve solid waste performance and mitigate corrosion of tanks and piping supporting the Effiuent Treatment Facility evaporator. This approach provides a life-cycle benefit to solid waste performance and reduction of groundwater contaminants.

  14. Contrasting patterns of coral bleaching susceptibility in 2010 suggest an adaptive response to thermal stress.

    Science.gov (United States)

    Guest, James R; Baird, Andrew H; Maynard, Jeffrey A; Muttaqin, Efin; Edwards, Alasdair J; Campbell, Stuart J; Yewdall, Katie; Affendi, Yang Amri; Chou, Loke Ming

    2012-01-01

    Coral bleaching events vary in severity, however, to date, the hierarchy of susceptibility to bleaching among coral taxa has been consistent over a broad geographic range and among bleaching episodes. Here we examine the extent of spatial and temporal variation in thermal tolerance among scleractinian coral taxa and between locations during the 2010 thermally induced, large-scale bleaching event in South East Asia. Surveys to estimate the bleaching and mortality indices of coral genera were carried out at three locations with contrasting thermal and bleaching histories. Despite the magnitude of thermal stress being similar among locations in 2010, there was a remarkable contrast in the patterns of bleaching susceptibility. Comparisons of bleaching susceptibility within coral taxa and among locations revealed no significant differences between locations with similar thermal histories, but significant differences between locations with contrasting thermal histories (Friedman = 34.97; pBleaching was much less severe at locations that bleached during 1998, that had greater historical temperature variability and lower rates of warming. Remarkably, Acropora and Pocillopora, taxa that are typically highly susceptible, although among the most susceptible in Pulau Weh (Sumatra, Indonesia) where respectively, 94% and 87% of colonies died, were among the least susceptible in Singapore, where only 5% and 12% of colonies died. The pattern of susceptibility among coral genera documented here is unprecedented. A parsimonious explanation for these results is that coral populations that bleached during the last major warming event in 1998 have adapted and/or acclimatised to thermal stress. These data also lend support to the hypothesis that corals in regions subject to more variable temperature regimes are more resistant to thermal stress than those in less variable environments.

  15. Response of coral assemblages to thermal stress: are bleaching intensity and spatial patterns consistent between events?

    Science.gov (United States)

    Penin, Lucie; Vidal-Dupiol, Jeremie; Adjeroud, Mehdi

    2013-06-01

    Mass bleaching events resulting in coral mortality are among the greatest threats to coral reefs, and are projected to increase in frequency and intensity with global warming. Achieving a better understanding of the consistency of the response of coral assemblages to thermal stress, both spatially and temporally, is essential to determine which reefs are more able to tolerate climate change. We compared variations in spatial and taxonomic patterns between two bleaching events at the scale of an island (Moorea Island, French Polynesia). Despite similar thermal stress and light conditions, bleaching intensity was significantly lower in 2007 (approximately 37 % of colonies showed signs of bleaching) than in 2002, when 55 % of the colonies bleached. Variations in the spatial patterns of bleaching intensity were consistent between the two events. Among nine sampling stations at three locations and three depths, the stations at which the bleaching response was lowest in 2002 were those that showed the lowest levels of bleaching in 2007. The taxonomic patterns of susceptibility to bleaching were also consistent between the two events. These findings have important implications for conservation because they indicate that corals are capable of acclimatization and/or adaptation and that, even at small spatial scales, some areas are consistently more susceptible to bleaching than others.

  16. Can heterotrophic uptake of dissolved organic carbon and zooplankton mitigate carbon budget deficits in annually bleached corals?

    Science.gov (United States)

    Levas, Stephen; Grottoli, Andréa G.; Schoepf, Verena; Aschaffenburg, Matthew; Baumann, Justin; Bauer, James E.; Warner, Mark E.

    2016-06-01

    Annual coral bleaching events due to increasing sea surface temperatures are predicted to occur globally by the mid-century and as early as 2025 in the Caribbean, and severely impact coral reefs. We hypothesize that heterotrophic carbon (C) in the form of zooplankton and dissolved organic carbon (DOC) is a significant source of C to bleached corals. Thus, the ability to utilize multiple pools of fixed carbon and/or increase the amount of fixed carbon acquired from one or more pools of fixed carbon (defined here as heterotrophic plasticity) could underlie coral acclimatization and persistence under future ocean-warming scenarios. Here, three species of Caribbean coral— Porites divaricata, P. astreoides, and Orbicella faveolata—were experimentally bleached for 2.5 weeks in two successive years and allowed to recover in the field. Zooplankton feeding was assessed after single and repeat bleaching, while DOC fluxes and the contribution of DOC to the total C budget were determined after single bleaching, 11 months on the reef, and repeat bleaching. Zooplankton was a large C source for P. astreoides, but only following single bleaching. DOC was a source of C for single-bleached corals and accounted for 11-36 % of daily metabolic demand (CHARDOC), but represented a net loss of C in repeat-bleached corals. In repeat-bleached corals, DOC loss exacerbated the negative C budgets in all three species. Thus, the capacity for heterotrophic plasticity in corals is compromised under annual bleaching, and heterotrophic uptake of DOC and zooplankton does not mitigate C budget deficits in annually bleached corals. Overall, these findings suggest that some Caribbean corals may be more susceptible to repeat bleaching than to single bleaching due to a lack of heterotrophic plasticity, and coral persistence under increasing bleaching frequency may ultimately depend on other factors such as energy reserves and symbiont shuffling.

  17. Effect of nightguard vital bleaching gel on the color stability of provisional restorative materials

    Directory of Open Access Journals (Sweden)

    Salwa Omar Bajunaid

    2016-01-01

    Conclusions: Composite-based provisional material showed highest color stability when exposed to vital tooth bleaching gel, whereas methacrylate-based material was the least color stable. Polycarbonate crowns were more color stable when exposed to 15% bleaching gel as opposed to 10% bleaching gel.

  18. Transcriptomic responses to darkness stress point to common coral bleaching mechanisms

    Science.gov (United States)

    Desalvo, M. K.; Estrada, A.; Sunagawa, S.; Medina, Mónica

    2012-03-01

    Coral bleaching occurs in response to numerous abiotic stressors, the ecologically most relevant of which is hyperthermic stress due to increasing seawater temperatures. Bleaching events can span large geographic areas and are currently a salient threat to coral reefs worldwide. Much effort has been focused on understanding the molecular and cellular events underlying bleaching, and these studies have mainly utilized heat and light stress regimes. In an effort to determine whether different stressors share common bleaching mechanisms, we used complementary DNA (cDNA) microarrays for the corals Acropora palmata and Montastraea faveolata (containing >10,000 features) to measure differential gene expression during darkness stress. Our results reveal a striking transcriptomic response to darkness in A. palmata involving chaperone and antioxidant up-regulation, growth arrest, and metabolic modifications. As these responses were previously measured during thermal stress, our results suggest that different stressors may share common bleaching mechanisms. Furthermore, our results point to hypoxia and endoplasmic reticulum stress as critical cellular events involved in molecular bleaching mechanisms. On the other hand, we identified a meager transcriptomic response to darkness in M. faveolata where gene expression differences between host colonies and sampling locations were greater than differences between control and stressed fragments. This and previous coral microarray studies reveal the immense range of transcriptomic responses that are possible when studying two coral species that differ greatly in their ecophysiology, thus pointing to the importance of comparative approaches in forecasting how corals will respond to future environmental change.

  19. Preheat-induced signal enhancement in the infrared stimulated luminescence of young and bleached sediment samples

    International Nuclear Information System (INIS)

    Richardson, C.A.

    2000-01-01

    Natural and laboratory bleached surface and young samples of potassium feldspar sand separates and polymineral silt had their infrared stimulated luminescence (IRSL) signal measured before and after preheating at 220 deg. C for 10 min or 160 deg. C for 16 h. For both preheats, the laboratory bleached sand samples underwent a signal enhancement which was stable with laboratory storage. The youngest samples also showed natural signal enhancement. The silt sample showed no recuperation of bleached signal on preheating, but some in the natural signal. A range of filtered bleaches was applied to one surface sand sample. Signal levels before and after preheating were reduced by filtering out the UV from the bleaching spectrum. The unfiltered bleach, however, most closely reproduced the behaviour of the natural sample

  20. Effects of bleaching agents on human enamel light reflectance.

    Science.gov (United States)

    Markovic, Ljubisa; Fotouhi, Kasra; Lorenz, Heribert; Jordan, Rainer A; Gaengler, Peter; Zimmer, Stefan

    2010-01-01

    Tooth whitening has been associated with splitting-up chromogenic molecules by hydrogen peroxides. Though micromorphological alterations are well documented, little is known about optical changes as a function of shifting in wavelengths. Therefore, the aim of the current study was to measure reflectance changes after bleaching in vitro by using a spectrometer. Forty-eight enamel slabs (diameter = 5 mm) were prepared from the sound enamel of extracted human teeth that were: 1) fully impacted, 2) from juveniles ages 10 to 16 years, 3) from adults 35 to 45 years of age and 4) from seniors older than age 65. In all specimens, the baseline total reflectance measurement was performed with a computer-assisted spectrometer (Ocean Optics, Dunedin, FL, USA) within wavelengths (wl) from 430 nm to 800 nm. Four enamel samples of each age group were exposed to either 10% or 15% carbamide peroxide (Illuminé Home, Dentsply, Konstanz, Germany) or 35% hydrogen peroxide (Pola Office, SDI Limited, Victoria, Australia). After surface treatment, all slabs underwent total reflectance measurement again. Statistical analysis was calculated at wl 450, 500 and 750 nm using the Student's paired t-test and one-way variance analysis. Total reflectance significantly increased after bleaching at all enamel maturation stages, irrespective of the bleaching agent concentration, for wl 450 nm (blue) and 500 nm (green) with penamel from adults and seniors (pwhitening of the dental enamel works at different maturation stages, even in impacted teeth. This effect is irrespective of the bleaching protocol used and the bleaching agent concentration.

  1. "The fairer the better?" Use of potentially toxic skin bleaching products.

    Science.gov (United States)

    Darj, Elisabeth; Infanti, Jennifer J; Ahlberg, Beth Maina; Okumu, Jecinta

    2015-12-01

    Skin bleaching is a widespread phenomenon in spite of their potentially toxic health effects. This study aimed to determine if such products are used in Sweden in particular by pregnant women, furthermore to explore immigrant women's view skin bleaching. 455 pregnant women completed a questionnaire, which were statistically analysed. Focus groups and individual interviews were conducted with immigrant women, content analysis was used to assess the data. Skin bleaching products were used by 2.6% of pregnant women, significantlly more by women born in non-European countries. Motivating factors were associated with the concept of beauty together with social and economic advantages. The women had low awareness of the potential health risks of the products. Regulations on the trade of skin bleaching products have not effectively reduced the availability of the products in Sweden nor the popularity of skin bleaching. There is need for further research especially among pregnant women and possible effects on newborns. Products should be tested for toxicity. Public health information should be developed and health care providers educated and aware of this practice, due to their potential negative health implications.

  2. The Use of Mg(OH2 in the Final Peroxide Bleaching Stage of Wheat Straw Pulp

    Directory of Open Access Journals (Sweden)

    Yan-Lan Liu

    2013-11-01

    Full Text Available Magnesium-based alkali is an attractive alkaline source for the peroxide bleaching of high-yield pulp. However, little information is available on Mg(OH2 application in the final peroxide bleaching stage of wheat straw pulp. The use of Mg(OH2 was demonstrated as a partial replacement for NaOH in the peroxide bleaching of a chelated oxygen-delignified wheat straw pulp. The yield, viscosity, and strength properties of bleached pulp significantly increased with increasing replacement ratio of Mg(OH2, while the chemical oxygen demand load (COD of filtrate was decreased. For similar brightness of bleached pulp at a 24% replacement ratio of Mg(OH2, the tensile and tear indices were higher, by 2.1 Nm.g-1 and 1.75 mN*m2.g-1, respectively, than that of control pulp bleached with NaOH as the sole alkaline source. When the MgSO4 was eliminated and the dosage of Na2SiO3 was decreased in the bleaching process, the tear and burst indices of the bleached pulp were also enhanced, with the brightness maintained. Scanning electron microscopy (SEM showed that more swelling occurred in the fibers of bleached pulp from the Mg(OH2-based bleaching process. Fiber analysis indicated that peroxide bleaching with Mg(OH2 increased the proportion of fiber lengths between 0.20 to 1.20 mm and 1.20 to 7.60 mm.

  3. Coral diseases and bleaching on Colombian Caribbean coral reefs.

    Science.gov (United States)

    Navas-Camacho, Raúl; Gil-Agudelo, Diego Luis; Rodríguez-Ramírez, Alberto; Reyes-Nivia, María Catalina; Garzón-Ferreira, Jaime

    2010-05-01

    Since 1998 the National Monitoring System for the Coral Reefs of Colombia (SIMAC) has monitored the occurrence of coral bleaching and diseases in some Colombian coral reefs (permanent stations at San Andres Island, Rosario Islands, Tayrona, San Bernardo Islands and Urabá). The main purpose is to evaluate their health status and to understand the factors that have been contributing to their decline. To estimate these occurrences, annual surveys in 126 permanent belt transects (10 x 2m) with different depth intervals (3-6 meters, 9-12 meters and 15-18 meters) are performed at all reef sites. Data from the 1998-2004 period, revealed that San Andrés Island had many colonies with diseases (38.9 colonies/m2), and Urabá had high numbers with bleaching (54.4 colonies/m2). Of the seven reported coral diseases studied, Dark Spots Disease (DSD), and White Plague Disease (WPD) were noteworthy because they occurred in all Caribbean monitored sites, and because of their high interannual infection incidence. Thirty five species of scleractinian corals were affected by at least one disease and a high incidence of coral diseases on the main reef builders is documented. Bleaching was present in 34 species. During the whole monitoring period, Agaricia agaricites and Siderastrea siderea were the species most severely affected by DSD and bleaching, respectively. Diseases on species such as Agaricia fragilis, A. grahamae, A. humilis, Diploria clivosa, Eusmilia fastigiata, Millepora complanata, and Mycetophyllia aliciae are recorded for first time in Colombia. We present bleaching and disease incidences, kinds of diseases, coral species affected, reef localities studied, depth intervals of surveys, and temporal (years) variation for each geographic area. This variation makes difficult to clearly determine defined patterns or general trends for monitored reefs. This is the first long-term study of coral diseases and bleaching in the Southwestern Caribbean, and one of the few long

  4. Coral diseases and bleaching on Colombian Caribbean coral reefs

    Directory of Open Access Journals (Sweden)

    Raúl Navas-Camacho

    2010-05-01

    Full Text Available Since 1998 the National Monitoring System for the Coral Reefs of Colombia (SIMAC has monitored the occurrence of coral bleaching and diseases in some Colombian coral reefs (permanent stations at San Andres Island, Rosario Islands, Tayrona, San Bernardo Islands and Urabá. The main purpose is to evaluate their health status and to understand the factors that have been contributing to their decline. To estimate these occurrences, annual surveys in 126 permanent belt transects (10x2m with different depth intervals (3-6 meters, 9-12 meters and 15-18 meters are performed at all reef sites. Data from the 1998-2004 period, revealed that San Andrés Island had many colonies with diseases (38.9 colonies/m2, and Urabá had high numbers with bleaching (54.4 colonies/m2. Of the seven reported coral diseases studied, Dark Spots Disease (DSD, and White Plague Disease (WPD were noteworthy because they occurred in all Caribbean monitored sites, and because of their high interannual infection incidence. Thirty five species of scleractinian corals were affected by at least one disease and a high incidence of coral diseases on the main reef builders is documented. Bleaching was present in 34 species. During the whole monitoring period, Agaricia agaricites and Siderastrea siderea were the species most severely affected by DSD and bleaching, respectively. Diseases on species such as Agaricia fragilis, A.grahamae, A. humilis, Diploria clivosa, Eusmilia fastigiata, Millepora complanata, and Mycetophyllia aliciae are recorded for first time in Colombia. We present bleaching and disease incidences, kinds of diseases, coral species affected, reef localities studied, depth intervals of surveys, and temporal (years variation for each geographic area. This variation makes difficult to clearly determine defined patterns or general trends for monitored reefs. This is the first long-term study of coral diseases and bleaching in the Southwestern Caribbean, and one of the few

  5. Remote Sensing of Coral Bleaching Using Temperature and Light: Progress towards an Operational Algorithm

    Directory of Open Access Journals (Sweden)

    William Skirving

    2017-12-01

    Full Text Available The National Oceanic and Atmospheric Administration’s Coral Reef Watch program developed and operates several global satellite products to monitor bleaching-level heat stress. While these products have a proven ability to predict the onset of most mass coral bleaching events, they occasionally miss events; inaccurately predict the severity of some mass coral bleaching events; or report false alarms. These products are based solely on temperature and yet coral bleaching is known to result from both temperature and light stress. This study presents a novel methodology (still under development, which combines temperature and light into a single measure of stress to predict the onset and severity of mass coral bleaching. We describe here the biological basis of the Light Stress Damage (LSD algorithm under development. Then by using empirical relationships derived in separate experiments conducted in mesocosm facilities in the Mexican Caribbean we parameterize the LSD algorithm and demonstrate that it is able to describe three past bleaching events from the Great Barrier Reef (GBR. For this limited example, the LSD algorithm was able to better predict differences in the severity of the three past GBR bleaching events, quantifying the contribution of light to reduce or exacerbate the impact of heat stress. The new Light Stress Damage algorithm we present here is potentially a significant step forward in the evolution of satellite-based bleaching products.

  6. Effect of nightguard vital bleaching gel on the color stability of provisional restorative materials.

    Science.gov (United States)

    Bajunaid, Salwa Omar

    2016-01-01

    To assess the hypothesis that there was no difference in effect of 10% and 15% tooth bleaching agents on color stability of materials used for provisional fixed dental prosthesis. Fifteen samples from two materials used for provisional fixed dental prosthesis: methacrylate-based and composite-based materials and 15 preformed polycarbonate crowns soaked in bleaching gel or distilled water. Spectrophotometer recorded color of specimens at baseline, after 3, 7, and 14 days. Data were statistically analyzed using two-factor ANOVA test to compare the color stability of tested materials. Methyl-based provisional material exhibited statistically higher color change when exposed to 10% and 15% bleaching gel (delta EFNx01: 9.0 and 11.1, respectively) as compared to distilled water (delta EFNx01: 2.9). Delta EFNx01 of composite-based material specimens exposed to distilled water was statistically higher (6.3) than specimens exposed to 10% and 15% bleaching gel (1.5 and 1.1, respectively). Polycarbonate crowns showed a statistically lower color change when exposed to 15% (0.9) than to 10% bleaching gel (5.1) or distilled water (5.5). Composite-based provisional material showed highest color stability when exposed to vital tooth bleaching gel, whereas methacrylate-based material was the least color stable. Polycarbonate crowns were more color stable when exposed to 15% bleaching gel as opposed to 10% bleaching gel.

  7. Coral bleaching on high-latitude marginal reefs at Sodwana Bay, South Africa

    Energy Technology Data Exchange (ETDEWEB)

    Celliers, Louis; Schleyer, Michael H

    2002-12-01

    Coral bleaching, involving the expulsion of symbiotic zooxanthellae from the host cells, poses a major threat to coral reefs throughout their distributional range. The role of temperature in coral bleaching has been extensively investigated and is widely accepted. A bleaching event was observed on the marginal high-latitude reefs of South Africa located at Sodwana Bay during the summer months of 2000. This was associated with increased sea temperatures with high seasonal peaks in summer and increased radiation in exceptionally clear water. The bleaching was limited to Two-mile Reef and Nine-mile Reef at Sodwana Bay and affected <12% of the total living cover on Two-mile Reef. Montipora spp., Alveopora spongiosa and Acropora spp. were bleached, as well as some Alcyoniidae (Sinularia dura, Lobophytum depressum, L. patulum). A cyclical increase in sea temperature (with a period of 5-6 years) was recorded during 1998-2000 in addition to the regional temperature increase caused by the El Nino Southern Oscillation phenomenon. The mean sea temperature increased at a rate of 0.27 deg. C year{sup -1} from May 1994 to April 2000. High maximum temperatures were measured (>29 deg. C). The lowest mean monthly and the mean maximum monthly temperatures at which coral bleaching occurred were 27.5 and 28.8 deg. C, respectively, while the duration for which high temperatures occurred in 2000 was 67 days at {>=}27.5 deg. C (4 days at {>=}28.8 deg. C). Increased water clarity and radiation appeared to be a synergistic cause in the coral bleaching encountered at Sodwana Bay.

  8. Enzyme Activities in Waste Water and Activated Sludge

    DEFF Research Database (Denmark)

    Nybroe, Ole; Jørgensen, Per Elberg; Henze, Mogens

    1992-01-01

    The purpose of the present study was to evaluate the potential of selected enzyme activity assays to determine microbial abundance and heterotrophic activity in waste water and activated sludge. In waste water, esterase and dehydrogenase activities were found to correlate with microbial abundance...... measured as colony forming units of heterotrophic bacteria. A panel of four enzyme activity assays, α-glucosidase, alanine-aminopeptidase, esterase and dehydrogenase were used to characterize activated sludge and anaerobic hydrolysis sludge from a pilot scale plant. The enzymatic activity profiles were...... distinctly different, suggesting that microbial populations were different, or had different physiological properties, in the two types of sludge. Enzyme activity profiles in activated sludge from four full-scale plants seemed to be highly influenced by the composition of the inlet. Addition of hydrolysed...

  9. Contrasting Patterns of Coral Bleaching Susceptibility in 2010 Suggest an Adaptive Response to Thermal Stress

    Science.gov (United States)

    Guest, James R.; Baird, Andrew H.; Maynard, Jeffrey A.; Muttaqin, Efin; Edwards, Alasdair J.; Campbell, Stuart J.; Yewdall, Katie; Affendi, Yang Amri; Chou, Loke Ming

    2012-01-01

    Background Coral bleaching events vary in severity, however, to date, the hierarchy of susceptibility to bleaching among coral taxa has been consistent over a broad geographic range and among bleaching episodes. Here we examine the extent of spatial and temporal variation in thermal tolerance among scleractinian coral taxa and between locations during the 2010 thermally induced, large-scale bleaching event in South East Asia. Methodology/Principal Findings Surveys to estimate the bleaching and mortality indices of coral genera were carried out at three locations with contrasting thermal and bleaching histories. Despite the magnitude of thermal stress being similar among locations in 2010, there was a remarkable contrast in the patterns of bleaching susceptibility. Comparisons of bleaching susceptibility within coral taxa and among locations revealed no significant differences between locations with similar thermal histories, but significant differences between locations with contrasting thermal histories (Friedman = 34.97; pSingapore, where only 5% and 12% of colonies died. Conclusions/Significance The pattern of susceptibility among coral genera documented here is unprecedented. A parsimonious explanation for these results is that coral populations that bleached during the last major warming event in 1998 have adapted and/or acclimatised to thermal stress. These data also lend support to the hypothesis that corals in regions subject to more variable temperature regimes are more resistant to thermal stress than those in less variable environments. PMID:22428027

  10. Microleakage comparison of glass-ionomer and white mineral trioxide aggregate used as a coronal barrier in nonvital bleaching.

    Science.gov (United States)

    Vosoughhosseini, Sepideh; Lotfi, Mehrdad; Shahmoradi, Kaveh; Saghiri, Mohammad-Ali; Zand, Vahid; Mehdipour, Masoumeh; Ranjkesh, Bahram; Mokhtari, Hadi; Salemmilani, Amin; Doosti, Sirvan

    2011-11-01

    There is some evidence that the pH at the root surface is reduced by intracoronal placement of bleaching pastes, which is known to enhance osteoclastic activity. Therefore, it is recommended that a protective barrier be used over the canal filling to prevent leakage of bleaching agents. Glass-ionomer (GI) is commonly used as a coronal barrier before nonvital bleaching. Because mineral trioxide aggregate (MTA) creates high alkalinity after mixing with water, using MTA as a protective barrier over the canal filling may not only prevent leakage of bleaching agents and microorganisms, but may prevent cervical resorption. The aim of this study was to evaluate sealing ability of white mineral trioxide aggregate (WMTA) as a coronal barrier before nonvital bleaching. Root canals of one hundred thirty human maxillary incisors were instrumented and filled with gutta-percha without sealer. Gutta-percha was removed up to 3 mm below the cementoenamel junction (CEJ). The teeth were randomly divided into six experimental groups of 20 teeth each and two control groups of 5. In three experimental groups, WMTA was packed into the canal to the level of CEJ. In the remaining experimental groups, glass-ionomer (GI) was used as a coronal barrier. After a 24-hour incubation period, one of the following three bleaching agents was placed in the access cavity of each of the WMTA or GI groups. These three bleaching agents were 30% hydrogen peroxide, sodium perborate mixed with 30% hydrogen peroxide, and sodium perborate mixed with distilled water. The bleaching agents were replaced every 3 days for three times. In the positive controls, no coronal barrier was used. In the negative controls, all the tooth surfaces were covered by two layers of nail varnish. Microleakage was evaluated using protein leakage test. Statistical analyses were performed with the Kruskal-Wallis and Mann-Whitney tests. The experimental groups showed minimum leakage which was not significantly more than tha in the

  11. Elevated temperatures and bleaching on a high latitude coral reef: the 1988 Bermuda event

    Science.gov (United States)

    Cook, Clayton B.; Logan, Alan; Ward, Jack; Luckhurst, Brian; Berg, Carl J.

    1990-03-01

    Sea temperatures were normal in Bermuda during 1987, when Bermuda escaped the episodes of coral bleaching which were prevalent throughout the Caribbean region. Survey transecs in 1988 on 4 6 m reefs located on the rim margin and on a lagoonal patch reef revealed bleaching only of zoanthids between May and July. Transect and tow surveys in August and September revealed bleaching of several coral species; Millepora alcicornis on rim reefs was the most extensively affected. The frequency of bleaching in this species, Montastrea annularis and perhaps Diploria labyrinthiformis was significantly higher on outer reefs than on inshore reefs. This bleaching period coincided with the longest period of elevated sea temperatures in Bermuda in 38 years (28.9 30.9°C inshore, >28° offshore). By December, when temperatures had returned to normal, bleaching of seleractinians continued, but bleaching of M. alcicornis on the outer reefs was greatly reduced. Our observations suggest that corals which normally experience wide temperature ranges are less sensitive to thermal stress, and that high-latitude reef corals are sensitive to elevated temperatures which are within the normal thermal range of corals at lower latitudes.

  12. The combination of activated natural zeolite-bentonite to reduce Fe and Cu in refined bleached palm oil (RBPO) by using atomic absorption spectrophotometer method

    Science.gov (United States)

    Zakwan; Raja, PM; Giyanto

    2018-02-01

    Indonesia is one of the crude palm oil (CPO) production country in the world. As many products are derivated from the CPO, the quality must be increased continuously. One of the things that influence the quality of palm oil is the Fe and Cu content. The objective of this research was to reduce Fe and Cu content in Refined Bleached Palm Oil (RBPO). In processing CPO or Refined Bleachead Palm Oil (RBPO) may be contaminated by Fe and Cu from metal tank and pipe in the factory. The zeolite and bentonite was activated by maceration method using hydrochloric acid (0,1 N). Four batch reactions consisting of refined palm oil (RPO), activated natural zeolite-bentonite (ANZB) was bleached by heating and stirring them at about 105°C and 1200 rpm for 30 minutes. The results showed that all combinations of ANZB can reduce the Fe content. Thereafter, the optimal combination of ANZB was obtained in K1, K2 and K4 with Cu content 0.02 ppm. In the future, it is needed to study on the reduction of the Fe and Cu content in palm oil with the other adsorbent.

  13. Multi-scale ocean and climate drivers of widespread bleaching in the Coral Triangle

    Science.gov (United States)

    Drenkard, E.; Curchitser, E. N.; Kleypas, J. A.; Castruccio, F. S.

    2016-12-01

    The Maritime Continent is home to the Coral Triangle (CT): the global pinnacle of tropical coral biodiversity. Historically, extensive bleaching-induced mortality (caused by thermal stress) among corals in the CT has been associated with extremes in the El Niño Southern Oscillation (ENSO), particularly years when a strong El Niños transitions to a La Niña state (i.e., 1998 and 2010). Similarities in the spatial distribution of satellite-derived indices, and the multi-scale environmental drivers of elevated sea surface temperatures (SSTs) during the 1998 and 2010 bleaching events suggests a potential predictability that has important implications for reef conservation. Using numerical models and ocean and atmosphere reanalysis products, we discuss the roles of ENSO-associated anomalies in both large-scale atmospheric circulation patterns (e.g., South Asian Monsoon) and regional ocean-cooling mechanisms such as coastal upwelling, tropical storm activity, and divergent (i.e., upwelling) circulation patterns (e.g., the Mindanao Eddy) in determining SSTs and, consequently projected patterns of reef ecosystem vulnerability to thermal stress. Conditions associated with the recent and ongoing 2015/2016 coral bleaching and mortality will be compared/contrasted.

  14. Influence of bleaching regimen and time elapsed on microtensile bond strength of resin composite to enamel

    Directory of Open Access Journals (Sweden)

    Fulya Toksoy Topcu

    2017-01-01

    Full Text Available Objectives: The aim of this study was to evaluate the effects of time elapsed since bleaching and different bleaching regimens on the microtensile bond strength of resin composite to enamel. Methodology: Forty flattened buccal enamel surfaces were divided into four groups: An unbleached (control group and three bleaching groups. Control group specimens were not subjected to a bleaching regimen (Group 1, while those in the bleaching groups were bleached as follows: opalescence 10% (Group 2, whiteness perfect 16% (Group 3, and whiteness hydrogen peroxide 35% (Group 4. Thereafter, the bleached specimens were divided into three subgroups (n = 4 teeth each for restoration according to predetermined posttreatment time intervals (immediately, 1 week, and 2 weeks. Bonded specimens were then sectioned and subjected to μTBS testing. The data were analyzed using Kruskal–Wallis and Mann–Whitney U-tests at α = 0.05. Results: There was a significant difference in the μTBS of the resin composite to enamel in groups that were bonded immediately after bleaching and in the control group (P 0.05. Conclusions: Adhesive restorative procedures could not be performed immediately or after 1 week irrespective of the type or concentration of bleaching system used. Composite restorations on bleached enamel surfaces should be performed after an interval of at least 2 weeks.

  15. Regulation of higher-activity NARM wastes by EPA

    International Nuclear Information System (INIS)

    Bandrowski, M.S.

    1988-01-01

    The US Environmental Protection Agency (EPA) is currently developing standards for the disposal of low-level radioactive waste (LLW). As part of this Standard, EPA is including regulations for the disposal of naturally occurring and accelerator-produced radioactive material (NARM) wastes not covered under the Atomic Energy Act (AEA). The regulations will cover only higher-activity NARM wastes, defined as NARM waste with specific activity exceeding two nanocuries per gram. The proposed regulations will specify that NARM wastes exceeding the above limits, except for specific exempted items, must be disposed of in regulated radioactive waste disposal facilities. The proposed EPA regulations for NARM wastes will be discussed, as well as the costs and benefits of the regulation, how it will be implemented by EPA, and the rationale for covering only higher-activity NARM wastes exceeding two nanocuries per gram

  16. Expanding the utility of the Agricultural Research Service (ARS) process bleaching

    Science.gov (United States)

    The ARS Process for bleaching, biopolishing, and shrinkproofing wool is a novel alternative to chlorination and conventional bleaching. Consumer acceptance of domestic machine-washable, comfortable wool which can be worn next to the skin will lead to niche-market- potential and competitive, increas...

  17. Knowledge of the risks associated with skin bleaching among Togolese users.

    Science.gov (United States)

    Kpanake, L; Sastre, M T Munoz; Sorum, P C; Mullet, E

    2008-01-01

    We examined the extent of Togolese users' knowledge of the health risks associated with the regular use of bleaching agents. A massive underestimation of some of the main risks was discovered. The more frequent the use of bleaching agents, the higher the underestimation.

  18. Bleaching augments lipid peroxidation products in pistachio oil and its cytotoxicity

    Science.gov (United States)

    Pistachio consumption is associated with reductions in serum cholesterol and oxidative stress due to their constituents of unsaturated fats, phytosterols, fiber, and antioxidants. Bleaching has been applied to whiten nut shells for antifungal and cosmetic purposes. However, the impact of bleaching o...

  19. Sensory and Functionality Differences of Whey Protein Isolate Bleached by Hydrogen or Benzoyl Peroxide.

    Science.gov (United States)

    Smith, Tucker J; Foegeding, E Allen; Drake, MaryAnne

    2015-10-01

    Whey protein is a highly functional food ingredient used in a wide variety of applications. A large portion of fluid whey produced in the United States is derived from Cheddar cheese manufacture and contains annatto (norbixin), and therefore must be bleached. The objective of this study was to compare sensory and functionality differences between whey protein isolate (WPI) bleached by benzoyl peroxide (BP) or hydrogen peroxide (HP). HP and BP bleached WPI and unbleached controls were manufactured in triplicate. Descriptive sensory analysis and gas chromatography-mass spectrometry were conducted to determine flavor differences between treatments. Functionality differences were evaluated by measurement of foam stability, protein solubility, SDS-PAGE, and effect of NaCl concentration on gelation relative to an unbleached control. HP bleached WPI had higher concentrations of lipid oxidation and sulfur containing volatile compounds than both BP and unbleached WPI (P protein loss at pH 4.6 of WPI decreased by bleaching with either hydrogen peroxide or benzoyl peroxide (P whey with either BP or HP resulted in protein degradation, which likely contributed to functionality differences. These results demonstrate that bleaching has flavor effects as well as effects on many of the functionality characteristics of whey proteins. Whey protein isolate (WPI) is often used for its functional properties, but the effect of oxidative bleaching chemicals on the functional properties of WPI is not known. This study identifies the effects of hydrogen peroxide and benzoyl peroxide on functional and flavor characteristics of WPI bleached by hydrogen and benzoyl peroxide and provides insights for the product applications which may benefit from bleaching. © 2015 Institute of Food Technologists®

  20. Patterns of gene expression in a scleractinian coral undergoing natural bleaching.

    Science.gov (United States)

    Seneca, Francois O; Forêt, Sylvain; Ball, Eldon E; Smith-Keune, Carolyn; Miller, David J; van Oppen, Madeleine J H

    2010-10-01

    Coral bleaching is a major threat to coral reefs worldwide and is predicted to intensify with increasing global temperature. This study represents the first investigation of gene expression in an Indo-Pacific coral species undergoing natural bleaching which involved the loss of algal symbionts. Quantitative real-time polymerase chain reaction experiments were conducted to select and evaluate coral internal control genes (ICGs), and to investigate selected coral genes of interest (GOIs) for changes in gene expression in nine colonies of the scleractinian coral Acropora millepora undergoing bleaching at Magnetic Island, Great Barrier Reef, Australia. Among the six ICGs tested, glyceraldehyde 3-phosphate dehydrogenase and the ribosomal protein genes S7 and L9 exhibited the most constant expression levels between samples from healthy-looking colonies and samples from the same colonies when severely bleached a year later. These ICGs were therefore utilised for normalisation of expression data for seven selected GOIs. Of the seven GOIs, homologues of catalase, C-type lectin and chromoprotein genes were significantly up-regulated as a result of bleaching by factors of 1.81, 1.46 and 1.61 (linear mixed models analysis of variance, P coral bleaching response genes. In contrast, three genes, including one putative ICG, showed highly variable levels of expression between coral colonies. Potential variation in microhabitat, gene function unrelated to the stress response and individualised stress responses may influence such differences between colonies and need to be better understood when designing and interpreting future studies of gene expression in natural coral populations.

  1. Effect of enamel sealants on tooth bleaching and on the color stability of the result.

    Science.gov (United States)

    Corcodel, N; Hassel, A J; Sen, S; Saure, D; Rammelsberg, P; Lux, C J; Zingler, S

    2017-04-01

    The purpose of this in vitro study was to evaluate the effect of enamel sealants on bleaching of natural teeth by use of 40 % hydrogen peroxide in a dental surgery. The color stability of the results from bleaching was, furthermore, determined 10 months after the bleaching procedure. In a standardized setting, four sealants (Pro Seal ® , Light Bond™ Sealant, Protecto ® , and Clinpro™ XT Varnish) were applied to and removed from human teeth in accordance with the manufacturer's instructions. Natural teeth served as medium; half of the teeth were sealed and the others served as controls. Hydrogen peroxide gel (40 %; Opalescence Boost; Ultradent Products, South Jordan, UT, USA) was used as bleaching agent. Color measurement was performed with a spectroradiometer (Photoresearch PR670) before the bleaching process (T1) and 24 h (T2) and 10 months (T3) after bleaching. The spectroradiometer results were expressed by use of the Commission Internationale de l'Éclairage (CIE) L*a*b* color notation. The L*, a*, and b* values of the sealed and the unsealed surfaces were not significantly different at any time during the study (p > 0.05), irrespective of the sealant used. Ten months after the bleaching process, mean L*, a*, and b* values were lower than at 1-day post-bleaching; the mean value of ΔE between 1-day post-bleaching and 10 months post-bleaching was 2.46 (±3.1). The results of the study suggest that the effectiveness of professional tooth whitening is not appreciably affected by the application of the four sealants tested.

  2. Effect of Two-minute Application of 35% Sodium Ascorbate on Composite Bond Strength following Bleaching.

    Science.gov (United States)

    Ismail, Eman H; Kilinc, Evren; Hardigan, Patrick C; Rothrock, James K; Thompson, Jeffrey Y; Garcia-Godoy, Cristina

    2017-10-01

    The aim of this study is to assess the effect of 35% sodium ascorbate on microtensile bond strength of dentin immediately after bleaching with 35% hydrogen peroxide. A total of 25 sound human 3 rd molars were collected. Teeth were randomly divided into five groups for different treatments: Group I [bleaching + immediate bonding (i.e., restoration)], group II (bleaching + delayed bonding), group III (bleaching + sodium ascorbate + immediate bonding), group IV (bleaching + sodium ascorbate + delayed bonding), and group V (bonding only). After bleaching, but before bonding, groups II and IV were stored for 1 week in deionized water at 37°C. All samples were bonded using OptiBoned FL (Kerr) and Filtek Supreme (3M/ESPE). Teeth were sectioned into 1 × 1 mm 2 bars, and microtensile bond strength was tested with a universal testing machine (Instron 8841) at a cross-head speed of 0.5 mm/minute. Microtensile bond strength differed significantly across the five groups, with a significant reduction in microtensile bond strength observed for samples in group I relative to samples in any of the other treatment groups (p bleaching on composite bonding strength to dentin. The negative effects of bleaching on composite bonding can be neutralized by the application of the reversing agent sodium ascorbate thus, increasing the efficiency of clinic chair time. This is clinically relevant for those patients requiring restorative treatment immediately after in-office bleaching.

  3. In vitro evaluation of the chemical and morphological changes of the enamel surface using different bleaching techniques

    International Nuclear Information System (INIS)

    Mattos, Alessandra de Siervi

    2003-01-01

    'In vitro' evaluation through MEV and EDS of the morphological and chemical changes, respectively, of the bovine enamel, submitted to different bleaching techniques. For the MEV evaluation eighteen apical thirds were pigmented and divided into two parts. One half of each sample was the control and the other half was bleached according to the protocol of each test group (n= 6). Group I - home bleaching with a 10% carbamide peroxide; group II bleaching with 35% hydrogen peroxide and LED; group III - bleaching with 35% hydrogen peroxide with diode laser bleaching. The same procedure was done with the eighteen samples which were analyzed through EDS and which had their buccal surface grinded and polished before the bleaching procedure in order to obtain more precise values of the fraction of calcium and phosphorus. The results showed no morphological changes among the analyzed control halves and the bleached halves. There was not a statistical significant difference about Ca and P values, among the control halves and the bleached halves regarding the chemical components (p< 0,05). (author)

  4. Corrosion Study of Stainless Steels in Peracetic Acid Bleach Media With and Without Chloride and Chelant

    Directory of Open Access Journals (Sweden)

    Rohtash

    2014-12-01

    Full Text Available The paper industries are adopting non-chlorine containing chemicals e.g. peroxide, ozone, peracids etc. as alternate of chlorine based bleach chemicals e.g. chlorine and chlorine dioxide etc. with the aim of eco-friend atmospheres. Changeover to the new chemicals in the bleaching process is likely to affect the metallurgy of the existing bleach plants due to change in the corrosivity of the media. Accordingly, corrosion investigations were performed in a peracid namely peracetic acid to test the suitability of austenitic stainless steels 654SMO, 265SMO, 2205, 317L and 316L. The performance of above stainless steels was evaluated through long term immersion tests and Electrochemical polarization measurements in peracetic acid (PAA bleach media at pH value 4 maintaining concentration 0.2 % as active oxygen along with three chloride levels 0, 500 and 1000 ppm in pulp-free laboratory. To study the effect of corrosion inhibitors with extending limit of chloride in liquors, measurements were also made with two types of chelants- EDTA & MgSO4. The results showed that corrosivity of PAA reduced by addition of chelant while increased with concentration of Cl¯. The results also exhibited that EDTA is better inhibitor than MgSO4.

  5. Effects of green tea on the shear bond strength of orthodontic brackets after in-office vital bleaching.

    Science.gov (United States)

    Berger, Sandrine Bittencourt; Guiraldo, Ricardo Danil; Lopes, Murilo Baena; Oltramari-Navarro, Paula Vanessa; Fernandes, Thais Maria; Schwertner, Renata de Castro Alves; Ursi, Wagner José Silva

    2016-01-01

    The application of bleaching agents before placement of resin-bonded fixed appliances significantly, but temporarily, reduces bond strength to tooth structure. Antioxidants have been studied as a means to remove residual oxygen that compromises bonding to bleached enamel. This in vitro study evaluated whether green tea (GT) could restore the shear bond strength between bonded orthodontic brackets and bleached enamel. Six experimental groups were compared: group 1, no bleaching plus bracket bonding (positive control); group 2, bleaching with 35% hydrogen peroxide (HP) plus bracket bonding (negative control); group 3, 35% HP plus 10% sodium ascorbate (SA) plus bracket bonding; group 4, 35% HP plus 10% GT plus bracket bonding; group 5, no bleaching plus 10% SA plus bracket bonding; group 6, no bleaching plus 10% GT plus bracket bonding. Results suggested that GT, like SA, may be beneficial for bracket bonding immediately after bleaching.

  6. Optical bleaching of F-centers in BaFCl crystals after X-irradiation at room temperature

    International Nuclear Information System (INIS)

    Inabe, K.; Nakamura, S.; Takeuchi, N.

    1988-01-01

    The optical bleaching behaviour of the F-band formed by X-irradiation in BaFCl crystals is investigated paying attention to the difference between two types of F-centers. Optical absorption spectra, decay curves of the F-band under excitation with F light and excitation spectra of the bleaching are given and discussed. The bleaching of the F-bands is achieved by light in the absorption band irrespective of the component. Energy transfer among excited states of F-centers is responsible for the bleaching of F-centers in BaFCl crystals, involving energy transfer between F(Cl - ) and F(F - ) centers in their optical bleaching process

  7. Erosion and abrasion on dental structures undergoing at-home bleaching

    Directory of Open Access Journals (Sweden)

    Tarquinio SBC

    2011-07-01

    Full Text Available Flávio Fernando Demarco1, Sônia Saeger Meireles2, Hugo Ramalho Sarmento1, Raquel Venâncio Fernandes Dantas1, Tatiana Botero3, Sandra Beatriz Chaves Tarquinio11Graduate Program in Dentistry, School of Dentistry, Federal University of Pelotas, Brazil; 2Department of Operative Dentistry, Federal University of Paraíba, Brazil; 3Cariology, Restorative Science, and Endodontics Department, School of Dentistry, University of Michigan, MI, USAAbstract: This review investigates erosion and abrasion in dental structures undergoing at-home bleaching. Dental erosion is a multifactorial condition that may be idiopathic or caused by a known acid source. Some bleaching agents have a pH lower than the critical level, which can cause changes in the enamel mineral content. Investigations have shown that at-home tooth bleaching with low concentrations of hydrogen or carbamide peroxide have no significant damaging effects on enamel and dentin surface properties. Most studies where erosion was observed were in vitro. Even though the treatment may cause side effects like sensitivity and gingival irritation, these usually disappear at the end of treatment. Considering the literature reviewed, we conclude that tooth bleaching agents based on hydrogen or carbamide peroxide have no clinically significant influence on enamel/dentin mineral loss caused by erosion or abrasion. Furthermore, the treatment is tolerable and safe, and any adverse effects can be easily reversed and controlled.Keywords: peroxide, tooth bleaching, enamel, dentin, erosion, abrasion

  8. Recent activity on disposal of uranium waste

    International Nuclear Information System (INIS)

    Fujiwara, Noboru

    1999-01-01

    The concept on the disposal of uranium waste has not been discussed in the Atomic Energy Commission of Japan, but the research and development of it are carried out in the company and agency which are related to uranium waste. In this paper, the present condition and problems on disposal of uranium waste were shown in aspect of the nuclear fuel manufacturing companies' activity. As main contents, the past circumstances on the disposal of uranium waste, the past activity of nuclear fuel manufacturing companies, outline and properties of uranium waste were shown, and ideas of nuclear fuel manufacturing companies on the disposal of uranium waste were reported with disposal idea in the long-term program for development and utilization of nuclear energy. (author)

  9. Bleaching Susceptibility and Recovery of Colombian Caribbean Corals in Response to Water Current Exposure and Seasonal Upwelling

    Science.gov (United States)

    Bayraktarov, Elisa; Pizarro, Valeria; Eidens, Corvin; Wilke, Thomas; Wild, Christian

    2013-01-01

    Coral bleaching events are globally occurring more frequently and with higher intensity, mainly caused by increases in seawater temperature. In Tayrona National Natural Park (TNNP) in the Colombian Caribbean, local coral communities are subjected to seasonal wind-triggered upwelling events coinciding with stronger water currents depending on location. This natural phenomenon offers the unique opportunity to study potential water current-induced mitigation mechanisms of coral bleaching in an upwelling influenced region. Therefore, coral bleaching susceptibility and recovery patterns were compared during a moderate and a mild bleaching event in December 2010 and 2011, and at the end of the subsequent upwelling periods at a water current-exposed and -sheltered site of an exemplary bay using permanent transect and labeling tools. This was accompanied by parallel monitoring of key environmental variables. Findings revealed that in 2010 overall coral bleaching before upwelling was significantly higher at the sheltered (34%) compared to the exposed site (8%). Whereas 97% of all previously bleached corals at the water current-exposed site had recovered from bleaching by April 2011, only 77% recovered at the sheltered site, but 12% had died there. In December 2011, only mild bleaching (bleaching. This indicates the existence of local resilience patterns against coral bleaching in Caribbean reefs. PMID:24282551

  10. Correlation of Coral Bleaching Events and Remotely-Sensed Sea Surface Temperatures

    Science.gov (United States)

    1994-05-19

    water column. Diving on the reefs, they found significant tracts of bleached corals, zoanthids , gorgonians, and sea anemones (Bunckley-Williams and... zoanthids between May and July 1988 on shallow lagoonal reefs and rim margin reefs was the first indication of any sort of bleaching event at Bermuda

  11. Compaction and packaging of dry active municipal wastes

    International Nuclear Information System (INIS)

    Chen Zongming; Xi Xinmin

    1994-01-01

    The authors present the feature of a compaction system for active municipal wastes and the radiological monitoring results of workplace and environment. A variety of dry active municipal wastes could be compacted by this system. Volume reduction factor attained to 5 to 7 for soft wastes and 8 to 13 for hard wastes. No evident radiological impact was found on workplace and environment

  12. Mechanistic insights into the bleaching of melanin by alkaline hydrogen peroxide.

    Science.gov (United States)

    Smith, R A W; Garrett, B; Naqvi, K R; Fülöp, A; Godfrey, S P; Marsh, J M; Chechik, V

    2017-07-01

    This work aims to determine the roles of reactive oxygen species HO∙ and HO 2 - in the bleaching of melanins by alkaline hydrogen peroxide. Experiments using melanosomes isolated from human hair indicated that the HO∙ radical generated in the outside solution does not contribute significantly to bleaching. However, studies using soluble Sepia melanin demonstrated that both HO 2 - and HO∙ will individually bleach melanin. Additionally, when both oxidants are present, bleaching is increased dramatically in both rate and extent. Careful experimental design enabled the separation of the roles and effects of these key reactive species, HO∙ and HO 2 - . Rationalisation of the results presented, and review of previous literature, allowed the postulation of a simplified general scheme whereby the strong oxidant HO∙ is able to pre-oxidise melanin units to o-quinones enabling more facile ring opening by the more nucleophilic HO 2 - . In this manner the efficiency of the roles of both species is maximised. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. The effect of bleaching agents on the microhardness of dental aesthetic restorative materials.

    Science.gov (United States)

    Türker, S B; Biskin, T

    2002-07-01

    This study investigated the effects of three home bleaching agents on the microhardness of various dental aesthetic restorative materials. The restorative materials were: feldspatic porcelain, microfilled composite resin and light-cured modified glass-ionomer cement and the bleaching agents Nite-White (16% carbamide peroxide), Opalescence (10% carbamide peroxide and carbapol jel) and Rembrandt (10% carbamide peroxide jel). A total of 90 restorative material samples were prepared 1 cm diameter and 6 mm thick and kept in distilled water for 24 h before commencing bleaching which was carried out for 8 h day-1 for 4 weeks. Microhardness measurements were then made using a Tukon tester. Statistically significant differences with respect to unbleached controls were found only for the feldspatic porcelain and microfilled composite resins (P light cured modified glass-ionomer cement. For the composite resin, whereas Nite-White increased its microhardness, the other bleaching agents decreased it. There were no significant differences between the bleaching agents for any of the restorative materials.

  14. INFLUENCE OF BLEACHING WITH OZONE AND PEROXIDO OF HYDROGEN IN THE YIELD AND QUALITY OF SECONDARY FIBERS

    Directory of Open Access Journals (Sweden)

    Gustavo Ventorim

    2010-08-01

    Full Text Available In this study, Total Chlorine Free (TCF bleaching processes were evaluated for bleaching a secondary fiber of different origens. The samples were bleached to a target brightness of 78 % ISO. The results were interpreted on the basis of chemical cost to reach the target brightness, bleaching yield and bleached pulp quality as measured by viscosity, fluorescence and b* color coordinate. The ozone stage was responsible for improve TCF bleaching performance. The pulp bleached by sequences contained a ozone stage followed by chelation, without interstage washing (ZQ, and a final hydrogen peroxide stage unpressurized (P or pressurized with oxygen (PO, designed as (ZQ(PO showed good results. These sequences decreased pulp b* coordinate significantly and fluorescence slightly. For  all three bleaching processes, it was determined that process yield is negatively affected by hot alkaline stages such as oxygen, O, peroxide, P, and peroxide pressurized with oxygen, (PO and also for the origin of the pulps of secondary fibers.

  15. Clinical Comparison of At-Home and In-Office Dental Bleaching Procedures: A Randomized Trial of a Split-Mouth Design.

    Science.gov (United States)

    Machado, Lucas Silveira; Anchieta, Rodolfo Bruniera; dos Santos, Paulo Henrique; Briso, André Luiz; Tovar, Nick; Janal, Malvin N; Coelho, Paulo Guilherme; Sundfeld, Renato Herman

    2016-01-01

    The objective of this split-mouth clinical study was to compare a combination of in-office and at-home dental bleaching with at-home bleaching alone. Two applications of in-office bleaching were performed, with one appointment per week, using 38% hydrogen peroxide. At-home bleaching was performed with or without in-office bleaching using 10% carbamide peroxide in a custom-made tray every night for 2 weeks. The factor studied was the bleaching technique on two levels: Technique 1 (in-office bleaching combined with home bleaching) and Technique 2 (home bleaching only). The response variables were color change, dental sensitivity, morphology, and surface roughness. The maxillary right and left hemiarches of the participants were submitted to in-office placebo treatment and in-office bleaching, respectively (Phase 1), and at-home bleaching (Phase 2) treatment was performed on both hemiarches, characterizing a split-mouth design. Enamel surface changes and roughness were analyzed with scanning electron microscopy and optical interferometry using epoxy replicas. No statistically significant differences were observed between the bleaching techniques for either the visual or the digital analyses. There was a significant difference in dental sensitivity when both dental bleaching techniques were used, with in-office bleaching producing the highest levels of dental sensitivity after the baseline. Microscopic analysis of the morphology and roughness of the enamel surface showed no significant changes between the bleaching techniques. The two techniques produced similar results in color change, and the combination technique produced the highest levels of sensitivity. Neither technique promoted changes in morphology or surface roughness of enamel.

  16. Effects of the bleaching procedures on enamel micro-hardness: Plasma Arc and diode laser comparison.

    Science.gov (United States)

    Nematianaraki, Saeid; Fekrazad, Reza; Naghibi, Nasim; Kalhori, Katayoun Am; Junior, Aldo Brugnera

    2015-10-02

    One of the major side effects of vital bleaching is the reduction of enamel micro-hardness. The purpose of this study was to evaluate the influence of two different bleaching systems, Plasma Arc and GaAlAs laser, on the enamel micro-hardness. 15 freshly extracted human third molars were sectioned to prepare 30 enamel blocks (5×5 mm). These samples were then randomly divided into 2 groups of 15 each (n=15): a plasma arc bleaching group (: 350-700 nm) + 35% Hydrogen Peroxide whitening gel and a laser bleaching group (GaAlAs laser, λ: 810 nm, P: 10 W, CW, Special Tip) + 35% Hydrogen Peroxide whitening gel. Samples were subjected to the Vickers micro-hardness test (VHN) at a load of 50 g for 15s before and after treatment. Data were statistically analyzed by a Mann-Whitney test (p≤0.05). In the GaAlAs laser group, the enamel micro-hardness was 618.2 before and was reduced to 544.6 after bleaching procedures. In the plasma arc group, the enamel micro-hardness was 644.8 before and 498.9 after bleaching. Although both techniques significantly reduced VHN, plasma arc bleaching resulted in a 22.62% reduction in VHN for enamel micro-hardness, whereas an 11.89% reduction in VHN was observed for laser bleaching; this difference is statistically significant (plaser than with the plasma arc. Therefore GaAlAs laser bleaching has fewer harmful effects than plasma arc in respect to enamel micro-hardness reduction.

  17. Effect of Laser-assisted and Conventional In-office Bleaching on Monomer Release from Microhybrid and Nanohybrid Composite.

    Science.gov (United States)

    Omrani, Ladan Ranjbar; Farjadfar, Shayan; Pedram, Parham; Sadray, Sima; Kamangar, Sedighe Sadat Hashemi; Chiniforoush, Nasim

    2017-06-30

    Bleaching might affect structural properties of composite materials, and lead to monomer release. This study aimed to evaluate the effect of Laser-assisted and conventional in-office bleaching on the release of BIS-GMA, TEGDMA, and UDMA monomers from a nanohybrid and a microhybrid BIS-GMA based composite. 32 samples of each composite, were divided into 4 subgroups; subgroup 1: Conventional in-office bleaching (CIB) with the Opalescence Boost PF 38% gel, subgroup 2: Laser-assisted bleaching (LBO) with the Opalescence Boost PF 38% gel, subgroup 3: Laser-assisted bleaching (LBH) with the JW Power bleaching gel, subgroup 4: (CO) control without bleaching. All the samples were immersed in tubes of 2cc Ethanol 75% medium. The released monomers were analyzed using the high performance liquid chromatography (HPLC) method 24 h, 7, and 28 days. Data's were analyzed by Univariate Analysis of Variance test followed by Tukeys HSD. The amount of TEGDMA monomer released was not significant. However, nanohybrid composites showed significantly more monomer release than microhybrid composites (P Bleaching by laser with JW Power Bleaching gel led to more monomer release in nanohybrid composite.

  18. Improved tooth bleaching combining ozone and hydrogen peroxide--A blinded study.

    Science.gov (United States)

    Al-Omiri, Mahmoud K; Abul Hassan, Ra'ed S; AlZarea, Bader K; Lynch, Edward

    2016-03-01

    To evaluate the efficacy of tooth bleaching using ozone after hydrogen peroxide (H2O2) in comparison to the use of H2O2 alone. 70 extracted teeth were randomly distributed into two groups. Teeth surfaces in group 1 (n=35) were treated using 38% H2O2 and then were exposed to ozone for 60s and this ozonated peroxide mixture was left on the teeth for 20 min. Meanwhile, teeth in group 2 (n=35) were treated with H2O2 38% for 20 min. The L* a* b* and Vita Classic shade values of teeth were evaluated in both groups at base line, after application of H2O2 and ozone in group 1, and after application of H2O2 and then again after another application of ozone in group 2. The statistically significant changes were set at P ≤ 0.05. Baseline L* a* b* and Vita shade values were comparable between groups (P>0.05). Teeth obtained lighter shades following bleaching with both H2O2 and ozone or with H2O2 alone (P ≤ 0.05). Further bleaching with ozone for teeth already bleached with H2O2 alone showed further improvement of the shades of teeth (Pbleaching in both groups (P ≤ 0.05). More changes were obtained when both ozone and H2O2 were used (P ≤ 0.05). Bleaching with 38% H2O2 and ozone resulted in teeth with lighter shades than bleaching with 38% H2O2 alone. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Multivariate Analysis of Hemicelluloses in Bleached Kraft Pulp Using Infrared Spectroscopy.

    Science.gov (United States)

    Chen, Zhiwen; Hu, Thomas Q; Jang, Ho Fan; Grant, Edward

    2016-12-01

    The hemicellulose composition of a pulp significantly affects its chemical and physical properties and thus represents an important process control variable. However, complicated steps of sample preparation make standard methods for the carbohydrate analysis of pulp samples, such as high performance liquid chromatography (HPLC), expensive and time-consuming. In contrast, pulp analysis by attenuated total internal reflection Fourier transform infrared spectroscopy (ATR FT-IR) requires little sample preparation. Here we show that ATR FT-IR with discrete wavelet transform (DWT) and standard normal variate (SNV) spectral preprocessing offers a convenient means for the qualitative and quantitative analysis of hemicelluloses in bleached kraft pulp and alkaline treated kraft pulp. The pulp samples investigated include bleached softwood kraft pulps, bleached hardwood kraft pulps, and their mixtures, as obtained from Canadian industry mills or blended in a lab, and bleached kraft pulp samples treated with 0-6% NaOH solutions. In the principal component analysis (PCA) of these spectra, we find the potential both to differentiate all pulps on the basis of hemicellulose compositions and to distinguish bleached hardwood pulps by species. Partial least squares (PLS) multivariate analysis gives a 0.442 wt% root mean square errors of prediction (RMSEP) for the prediction of xylan content and 0.233 wt% RMSEP for the prediction of mannan content. These data all support the idea that ATR FT-IR has a great potential to rapidly and accurately predict the content of xylan and mannan for bleached kraft pulps (softwood, hardwood, and their mixtures) in industry. However, the prediction of xylan and mannan concentrations presented a difficulty for pulp samples with modified cellulose crystalline structure. © The Author(s) 2016.

  20. Solidification of highly active wastes

    International Nuclear Information System (INIS)

    Morris, J.B.

    1986-07-01

    This document contains the annual reports for the contracts: (A) Glass Technology; (B) Calcination of Highly Active Waste Liquors; (C) Formation and Trapping of Volatile Ruthenium; (D) Deposition of Ruthenium; (E) Enhancement of Off-Gas Aerosol Collection; (F) Volatilisation of Cs, Tc and Te in High Level Waste Vitrification. (author)

  1. Assessing the spatial distribution of coral bleaching using small unmanned aerial systems

    Science.gov (United States)

    Levy, Joshua; Hunter, Cynthia; Lukacazyk, Trent; Franklin, Erik C.

    2018-06-01

    Small unmanned aerial systems (sUAS) are an affordable, effective complement to existing coral reef monitoring and assessment tools. sUAS provide repeatable low-altitude, high-resolution photogrammetry to address fundamental questions of spatial ecology and community dynamics for shallow coral reef ecosystems. Here, we qualitatively describe the use of sUAS to survey the spatial characteristics of coral cover and the distribution of coral bleaching across patch reefs in Kānéohe Bay, Hawaii, and address limitations and anticipated technology advancements within the field of UAS. Overlapping sub-decimeter low-altitude aerial reef imagery collected during the 2015 coral bleaching event was used to construct high-resolution reef image mosaics of coral bleaching responses on four Kānéohe Bay patch reefs, totaling 60,000 m2. Using sUAS imagery, we determined that paled, bleached and healthy corals on all four reefs were spatially clustered. Comparative analyses of data from sUAS imagery and in situ diver surveys found as much as 14% difference in coral cover values between survey methods, depending on the size of the reef and area surveyed. When comparing the abundance of unhealthy coral (paled and bleached) between sUAS and in situ diver surveys, we found differences in cover from 1 to 49%, depending on the depth of in situ surveys, the percent of reef area covered with sUAS surveys and patchiness of the bleaching response. This study demonstrates the effective use of sUAS surveys for assessing the spatial dynamics of coral bleaching at colony-scale resolutions across entire patch reefs and evaluates the complementarity of data from both sUAS and in situ diver surveys to more accurately characterize the spatial ecology of coral communities on reef flats and slopes.

  2. Surviving coral bleaching events: porites growth anomalies on the Great Barrier Reef.

    Science.gov (United States)

    Cantin, Neal E; Lough, Janice M

    2014-01-01

    Mass coral bleaching affected large parts of the Great Barrier Reef (GBR) in 1998 and 2002. In this study, we assessed if signatures of these major thermal stress events were recorded in the growth characteristics of massive Porites colonies. In 2005 a suite of short (bleaching. Sites included inshore (Nelly Bay, Pandora Reef), annually affected by freshwater flood events, midshelf (Rib Reef), only occasionally affected by freshwater floods and offshore (Myrmidon Reef) locations primarily exposed to open ocean conditions. Annual growth characteristics (extension, density and calcification) were measured in 144 cores from 79 coral colonies and analysed over the common 24-year period, 1980-2003. Visual examination of the annual density bands revealed growth hiatuses associated with the bleaching years in the form of abrupt decreases in annual linear extension rates, high density stress bands and partial mortality. The 1998 mass-bleaching event reduced Porites calcification by 13 and 18% on the two inshore locations for 4 years, followed by recovery to baseline calcification rates in 2002. Evidence of partial mortality was apparent in 10% of the offshore colonies in 2002; however no significant effects of the bleaching events were evident in the calcification rates at the mid shelf and offshore sites. These results highlight the spatial variation of mass bleaching events and that all reef locations within the GBR were not equally stressed by the 1998 and 2002 mass bleaching events, as some models tend to suggest, which enabled recovery of calcification on the GBR within 4 years. The dynamics in annual calcification rates and recovery displayed here should be used to improve model outputs that project how coral calcification will respond to ongoing warming of the tropical oceans.

  3. Chronic nutrient enrichment increases prevalence and severity of coral disease and bleaching.

    Science.gov (United States)

    Vega Thurber, Rebecca L; Burkepile, Deron E; Fuchs, Corinne; Shantz, Andrew A; McMinds, Ryan; Zaneveld, Jesse R

    2014-02-01

    Nutrient loading is one of the strongest drivers of marine habitat degradation. Yet, the link between nutrients and disease epizootics in marine organisms is often tenuous and supported only by correlative data. Here, we present experimental evidence that chronic nutrient exposure leads to increases in both disease prevalence and severity and coral bleaching in scleractinian corals, the major habitat-forming organisms in tropical reefs. Over 3 years, from June 2009 to June 2012, we continuously exposed areas of a coral reef to elevated levels of nitrogen and phosphorus. At the termination of the enrichment, we surveyed over 1200 scleractinian corals for signs of disease or bleaching. Siderastrea siderea corals within enrichment plots had a twofold increase in both the prevalence and severity of disease compared with corals in unenriched control plots. In addition, elevated nutrient loading increased coral bleaching; Agaricia spp. of corals exposed to nutrients suffered a 3.5-fold increase in bleaching frequency relative to control corals, providing empirical support for a hypothesized link between nutrient loading and bleaching-induced coral declines. However, 1 year later, after nutrient enrichment had been terminated for 10 months, there were no differences in coral disease or coral bleaching prevalence between the previously enriched and control treatments. Given that our experimental enrichments were well within the ranges of ambient nutrient concentrations found on many degraded reefs worldwide, these data provide strong empirical support to the idea that coastal nutrient loading is one of the major factors contributing to the increasing levels of both coral disease and coral bleaching. Yet, these data also suggest that simple improvements to water quality may be an effective way to mitigate some coral disease epizootics and the corresponding loss of coral cover in the future. © 2013 John Wiley & Sons Ltd.

  4. The number of bleaching sessions influences pulp tissue damage in rat teeth.

    Science.gov (United States)

    Cintra, Luciano Tavares Angelo; Benetti, Francine; da Silva Facundo, Aguinaldo Cândido; Ferreira, Luciana Louzada; Gomes-Filho, João Eduardo; Ervolino, Edilson; Rahal, Vanessa; Briso, André Luiz Fraga

    2013-12-01

    Hydrogen peroxide tooth bleaching is claimed to cause alterations in dental tissue structures. This study investigated the influence of the number of bleaching sessions on pulp tissue in rats. Male Wistar rats were studied in 5 groups (groups 1S-5S) of 10 each, which differed by the number (1-5) of bleaching sessions. In each session, the animals were anesthetized, and 35% hydrogen peroxide gel was applied to 3 upper right molars. Two days after the experimental period, the animals were killed, and their jaws were processed for light microscope evaluation. Pulp tissue reactions were scored as follows: 1, no or few inflammatory cells and no reaction; 2, session, necrotic tissue in the pulp horns and underlying inflammatory changes were observed. The extent and intensity of these changes increased with the number of bleaching sessions. After 5 sessions, the changes included necrotic areas in the pulp tissue involving the second third of the radicular pulp and intense inflammation in the apical third. The number of bleaching sessions directly influenced the extent of pulp damage. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  5. Effects of cold light bleaching on the color stability of composite resins

    Science.gov (United States)

    Cao, Liqun; Huang, Lijuan; Wu, Meisheng; Wei, Hua; Zhao, Shouliang

    2015-01-01

    To evaluate the effects of cold light bleaching on the color stability of four restorations using a thermocycling stain challenge. 160 specimens (10 mm in diameter and 2 mm thick) were fabricated from 4 composite resins (Gradia Direct-A, Z350XT, Premisa, and Précis) and divided into 4 subgroups. Color was assessed according to the CIEL*a*b* color scale at baseline, after the first cycle of bleaching, after thermocycling stain challenges, and after the second cycle of bleaching. Mean values were compared using three-way analysis of variance, and multiple comparisons of the mean values were performed using the Tukey-Kramer test. All groups showed significant color changes after stain challenge, the color change was more significant in Gradia Direct and Z350XT than in Premisa and Précis. After the second cycle of bleaching, color mostly recovered to its original values. The color stability of Gradia Direct and Z350XT was inferior to that of Premisa and Précis. The discoloration of composite resin materials can be partly removed after cold light bleaching. PMID:26309549

  6. Patient and environmental service employee satisfaction of using germicidal bleach wipes for patient room cleaning.

    Science.gov (United States)

    Aronhalt, Kimberly C; McManus, James; Orenstein, Robert; Faller, Rebecca; Link, Mary

    2013-01-01

    More healthcare institutions are using bleach products which are sporicidal to reduce Clostridium difficile infection (CDI). There may be patient and employee concerns about the appearance of bleach residue left on surfaces, odors, and respiratory tract irritation. The intervention used bleach wipes for daily and terminal patient room cleaning to reduce transmission of CDI and was implemented on patient care units with a relatively high incidence of CDI. Both patients and Environmental Services (ES) staff were surveyed to assess their satisfaction of the bleach wipe product used during room cleaning. Patients (n = 94) (91%) continued to be very satisfied with how well their rooms were cleaned every day. Bleach wipes were well tolerated by patients (n = 44) (100%) surveyed on the medical units and less tolerated by patients (n = 50) (22%) on the hematology-oncology units. ES staff (6) reported less satisfaction and more respiratory irritation from using the bleach wipes; however, later their satisfaction improved. © 2012 National Association for Healthcare Quality.

  7. Study of the hydrogen peroxide bleaching agent effects on bovine enamel using X-ray fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Moreira, Ruda F.; Calazans, Fernanda S.; Miranda, Mauro S.; Santos, Ramon S.; Anjos, Marcelino J.; Assis, Joaquim T. [Universidade do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, RJ (Brazil)

    2013-07-01

    Hydrogen Peroxide's a bleaching agent capable of oxidizing a wide range of colored organic, causing discoloration and hence bleaching of the substrate, but some authors related the occurrence of side effects related to bleaching of the tooth structure, such as changes in morphology superficial. It was used 6 bovine incisors, each tooth was initially evaluated six times in different areas to obtain the count of elements phosphorus and calcium using X-Ray Fluorescence. The teeth were randomly divided in two groups: both groups were submitted to bleaching in office with hydrogen peroxide 38%, once a week during three weeks. Group 1 was stored in distilled water and group 2 in artificial saliva, between the sessions. The measurements were repeated every seven days before the bleaching treatment. Besides that, changes in mineral levels were always assessed in the same area and using the same procedure. It was observed that the bleaching was not able to demineralize the tooth enamel studied. (author)

  8. Study of the hydrogen peroxide bleaching agent effects on bovine enamel using X-ray fluorescence

    International Nuclear Information System (INIS)

    Moreira, Ruda F.; Calazans, Fernanda S.; Miranda, Mauro S.; Santos, Ramon S.; Anjos, Marcelino J.; Assis, Joaquim T.

    2013-01-01

    Hydrogen Peroxide's a bleaching agent capable of oxidizing a wide range of colored organic, causing discoloration and hence bleaching of the substrate, but some authors related the occurrence of side effects related to bleaching of the tooth structure, such as changes in morphology superficial. It was used 6 bovine incisors, each tooth was initially evaluated six times in different areas to obtain the count of elements phosphorus and calcium using X-Ray Fluorescence. The teeth were randomly divided in two groups: both groups were submitted to bleaching in office with hydrogen peroxide 38%, once a week during three weeks. Group 1 was stored in distilled water and group 2 in artificial saliva, between the sessions. The measurements were repeated every seven days before the bleaching treatment. Besides that, changes in mineral levels were always assessed in the same area and using the same procedure. It was observed that the bleaching was not able to demineralize the tooth enamel studied. (author)

  9. Experimentally Induced Bleaching in the Sea Anemone Exaiptasia Supports Glucose as a Main Metabolite Associated with Its Symbiosis

    Directory of Open Access Journals (Sweden)

    Víctor Hugo Molina

    2017-01-01

    Full Text Available Our current understanding of carbon exchange between partners in the Symbiodinium-cnidarian symbioses is still limited, even though studies employing carbon isotopes have made us aware of the metabolic complexity of this exchange. We examined glycerol and glucose metabolism to better understand how photosynthates are exchanged between host and symbiont. The levels of these metabolites were compared between symbiotic and bleached Exaiptasia pallida anemones, assaying enzymes directly involved in their metabolism. We measured a significant decrease of glucose levels in bleached animals but a significant increase in glycerol and G3P pools, suggesting that bleached animals degrade lipids to compensate for the loss of symbionts and seem to rely on symbiotic glucose. The lower glycerol 3-phosphate dehydrogenase but higher glucose 6-phosphate dehydrogenase specific activities measured in bleached animals agree with a metabolic deficit mainly due to the loss of glucose from the ruptured symbiosis. These results corroborate previous observations on carbon translocation from symbiont to host in the sea anemone Exaiptasia, where glucose was proposed as a main translocated metabolite. To better understand photosynthate translocation and its regulation, additional research with other symbiotic cnidarians is needed, in particular, those with calcium carbonate skeletons.

  10. Segregation of low-level dry active waste

    International Nuclear Information System (INIS)

    Kornblith, L. Jr.; Naughton, M.D.; Welsh, L.

    1984-01-01

    A program has been carried out to characterize the Dry Active Waste (DAW) stream from a typical PWR power plant in order to determine the usefulness of large-volume DAW monitors for segregating such waste in order to dispose of it in appropriate facilities. A waste monitor using plastic scintillation counters was used for measuring the waste. The monitor had a volume of about 300 liters and an overall efficiency of about 12% for a typical fission product mixture. It provides automatic compensation for background radioactivity and can measure a bag of waste in less than a minute, including background measurements. Six hundred consecutively generated bags of DAW were measured. These had a total activity of about one millicurie and an average specific activity of about 540 nanocuries per kilogram. About half of the bags contained less than 1000 nanocuries and had specific activities of less than 100 nanocuries per kilogram. Based on simplified preliminary calculations, it appears that an evaluation of the risks of disposal of bags such as these in a landfill other than a low-level waste disposal facility could be carried out that would demonstrate that such disposal of half or more of these bags would not result in any substantial hazard, either short or long term

  11. Effect of Home Bleaching on the Translucency of CAD/CAM Systems.

    Science.gov (United States)

    Karci, Muhammet; Demir, Necla

    2017-11-10

    To evaluate the effect of a home bleaching agent (Opalescence PF) on the translucency of CAD/CAM ceramic systems. The 28 sintered ceramic specimens (IPS Empress CAD and IPS e.max CAD; 15 mm long, 10 mm wide, 1 mm thick) were divided into two subgroups as control and bleaching groups (n = 7). Carbamide peroxide (CP), 16%, home bleaching agent was applied onto the surface of each specimen for 6 hours per day for 7 days. A spectrophotometer (VITA Easyshade Advance) was used to measure the CIE L * a * b * coordinates and the reflectance value (Y) of the specimens on white and black backgrounds. The translucency parameter (TP), contrast ratio (CR), and opalescence parameter (OP) of the specimens were calculated. The data were statistically analyzed using Kolmogorov-Smirnov, one-way ANOVA, Tukey's test, and Pearson's correlation. Statistically significant differences in the TP values after 16% CP bleaching treatment were observed (p ˂ 0.05); however, no significant differences were found in the OP and CR values after the surface treatment (p ˃ 0.05). According to our study, patients who have all-ceramic restorations in their mouths should be careful when using home bleaching agents, because whitening agents can affect the translucency of all-ceramic restorations such as e.max CAD and Empress CAD. © 2017 by the American College of Prosthodontists.

  12. A novel approach for the reuse of the textile bleaching wastewater

    International Nuclear Information System (INIS)

    Shaikh, I.A.

    2015-01-01

    In this paper, the efficiency of used hydrogen peroxide (H/sub 2/O/sub 2/) bleach bath was assessed for the elimination of hydrolyzed unfixed reactive dyes from cellulosic fabrics. The aim of this study was to reuse textile wastewater and develop a new textile dyeing and wash-off method with small quantities of water and chemicals, without compromising quality of dyeing. For this purpose, spent bleach bath having H/sub 2/O/sub 2/ was collected from a textile industry and used in wash-off step of fabric after dyeing with reactive dyes to determine colour fastness properties and shade strength of selected reactive dyes. Five dyeings were carried out, using C. I. Reactive Yellow 138, C. I. Reactive Orange 122, C. I. Reactive Red 195, C. I. Reactive Blue 221, and C. I. Reactive Black 5 and dyed samples were passed through both conventional wash-off and new wash-off method containing spent bleach bath. Washing fastness, rubbing fastness, change of colour, and magnitude of total colour difference ( E*) values of both washed-off fabrics were compared. The colourfastness properties and final shade of fabrics washed-off with spent bleach were found to be comparable to those washed-off conventionally. This study concludes that spent bleach bath containing H/sub 2/O/sub 2/ is a potential nominee for the removal of hydrolyzed reactive dyes from cotton fabrics. (author)

  13. Surface discoloration of composite resins: Effects of staining and bleaching.

    Science.gov (United States)

    Poggio, Claudio; Beltrami, Riccardo; Scribante, Andrea; Colombo, Marco; Chiesa, Marco

    2012-09-01

    The purpose of this in vitro study was to evaluate surface discoloration of three microhybrid composite resins (Esthet•X HD, Clearfil AP-X, Gradia Direct) and five nanohybrid composite resins (Ceram•X, GC Kalore, G-aenial, Grandio, GrandioSO), after staining and bleaching procedures. The composite resins were polymerized with a curing light (Celalux II, Voco, Cuxhaven, Germany) into 160 silicon molds (6,4 mm in diameter and 2 mm in thickness) to obtain identical specimens. Twenty samples for each composite resin were prepared. The specimens were polished using an automated polishing machine with the sequence of 600-, 800-, 1000-grit abrasive paper under water irrigation. The specimens were immersed in tea and distilled water: the specimens were dipped for 20 min, once a day (every 24 h), for 14 days into the drinks. The specimens were then bleached with carbamide peroxide at 17% (Perfect Bleach-Voco). The color of specimens was measured with a spectrophotometer according to the CIE L(*)a(*)b(*) system after light-polymerization of composite resin specimens, after 7 days, after 14 days, and after bleaching. The color difference h index (DEab(*)) between each measurement was calculated. Statistical analysis was made using analysis of variance (ANOVA). All specimens showed a significant increase in staining with a similar trend and no significant differences between microhybrid and nanohybrid composite resins. After whitening procedures, materials tested showed both significant and unsignificant differences of the h index. Microhybrid and nanohybrid composite resins had similar in vitro surface discoloration in tea. After bleaching, discoloration was removed from some composite resins tested.

  14. Project Overview: A Reef Manager's Guide to Coral Bleaching ...

    Science.gov (United States)

    The purpose of this report is to provide the latest scientific knowledge and discuss available management options to assist local and regional managers in responding effectively to mass coral bleaching events. Background A Reef Manager’s Guide to Coral Bleaching is the result of a collaborative effort by over 50 scientists and managers to: (1) share the best available scientific information on climate-related coral bleaching; and (2) compile a tool kit of currently available strategies for adaptive management of coral reefs in a changing climate. The result is a compendium of current information, tools, and practical suggestions to aid managers in their efforts to protect reefs in a way that maximizes reef resilience in the face of continuing climate change. The Guide is a joint publication of the National Oceanic and Atmospheric Administration, the Great Barrier Reef Marine Park Authority, and The World Conservation Union, with author contributions from a variety of international partners from government agencies, non-governmental organizations, and academic institutions. EPA’s Office of Research and Development was a major contributor to the Guide through authorship and participation in the final review and editing process for the entire report. A Reef Manager’s Guide to Coral Bleaching is the result of a collaborative effort by over 50 scientists and managers to: (1) share the best available scientific information on climate-related coral blea

  15. Occupational eczema and asthma in a hairdresser caused by hair-bleaching products

    DEFF Research Database (Denmark)

    Hougaard, Majken G; Menné, Torkil; Søsted, Heidi

    2012-01-01

    Occupational allergic contact eczema and asthma caused by bleaching agents is seen in hairdressers. Bleaching agents contain persulfate salts, which are known to induce immediate reactions such as rhinitis, asthma, contact urticaria, and anaphylaxis. The immunologic mechanism is not, however, ful...

  16. Microbial dinitrogen fixation in coral holobionts exposed to thermal stress and bleaching.

    Science.gov (United States)

    Cardini, Ulisse; van Hoytema, Nanne; Bednarz, Vanessa N; Rix, Laura; Foster, Rachel A; Al-Rshaidat, Mamoon M D; Wild, Christian

    2016-09-01

    Coral holobionts (i.e., coral-algal-prokaryote symbioses) exhibit dissimilar thermal sensitivities that may determine which coral species will adapt to global warming. Nonetheless, studies simultaneously investigating the effects of warming on all holobiont members are lacking. Here we show that exposure to increased temperature affects key physiological traits of all members (herein: animal host, zooxanthellae and diazotrophs) of both Stylophora pistillata and Acropora hemprichii during and after thermal stress. S. pistillata experienced severe loss of zooxanthellae (i.e., bleaching) with no net photosynthesis at the end of the experiment. Conversely, A. hemprichii was more resilient to thermal stress. Exposure to increased temperature (+ 6°C) resulted in a drastic increase in daylight dinitrogen (N2 ) fixation, particularly in A. hemprichii (threefold compared with controls). After the temperature was reduced again to in situ levels, diazotrophs exhibited a reversed diel pattern of activity, with increased N2 fixation rates recorded only in the dark, particularly in bleached S. pistillata (twofold compared to controls). Concurrently, both animal hosts, but particularly bleached S. pistillata, reduced both organic matter release and heterotrophic feeding on picoplankton. Our findings indicate that physiological plasticity by coral-associated diazotrophs may play an important role in determining the response of coral holobionts to ocean warming. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

  17. Status of the Coral Reefs of Maldives after the Bleaching Event in 1998

    OpenAIRE

    Zahir, H.

    2000-01-01

    A pilot reef monitoring study was conducted in 1998 to assess the extent of coral bleaching in the Maldives. The aims of this monitoring exercise were: 1. To quantitatively document the post-bleaching status of the shallow-water coral communities on the reefs of the north, central and southern regions of Maldives. 2. To estimate bleaching-induced coral mortality by comparing data yielded by the pilot survey with data from previous surveys, especially those sites for which historical dat...

  18. Impact of Three Bleaching Events on the Reef Resiliency of Kāne‘ohe Bay, Hawai‘i

    Directory of Open Access Journals (Sweden)

    Keisha D. Bahr

    2017-12-01

    Full Text Available Coral bleaching events have been increasing in frequency and severity worldwide. The most prolonged global bleaching event began in 2014 and continued into 2017 impacting more reefs than any previous occurrence. Here we present the results of coral bleaching and mortality surveys conducted in Kāne‘ohe Bay O‘ahu, Hawai‘i and compare them to the only other widespread bleaching events to impact the main Hawaiian Islands in 1996 and 2014. Results from these surveys along with associated environmental factors were used to compare these events to gain a baseline understanding of the physical processes that influence localized bleaching dynamics under these extreme environmental conditions. Survey results show extensive variation in bleaching (1996–62%, 2014–45%, 2015–30% and cumulative mortality (1996— <1%, 2014–13%, 2015–22% between years. Bleaching prevalence was observed to decrease in certain reef areas across events, suggesting some acclimation and/or resilience, but possible increase susceptibility to mortality. Long-term monitoring sites show a similar temporal pattern of coral mortality and decline in coral cover, but revealed some reefs remained relatively un-impacted by consecutive high temperature events. Across the three bleaching events, we found that although circulation patterns can facilitate heating, the duration and magnitude of the high temperature event were the primary forcing functions for coral bleaching and mortality. Other localized primary drivers influencing water temperature such as irradiance, turbidity, and precipitation contributed to spatial variations. Recovery and resilience of this coral reef ecosystem is dependent on many factors including duration and magnitude of heating, resulting mortality levels, localized environmental factors in the bay, and coral species affected and their bleaching tolerances.

  19. Effects of hydrogen peroxide bleaching strip gels on dental restorative materials in vitro: surface microhardness and surface morphology.

    Science.gov (United States)

    Duschner, Heinz; Götz, Hermann; White, Donald J; Kozak, Kathleen M; Zoladz, James R

    2004-01-01

    This study examined the effects of peroxide tooth bleaching, including Crest Whitestrips hydrogen peroxide gel treatments, on the surface hardness and morphology of common dental restorative treatments. American Dental Association (ADA) recommended dental restorative materials, including amalgam, dental gold, porcelain, glass ionomer, and composites, were prepared according to manufacturers' instructions. A cycling treatment methodology was employed which alternated ex vivo human salivary exposures with bleaching treatments under conditions of controlled temperature and durations of treatment. Bleaching treatments included commercial Crest Whitestrips bleaching gels, which utilize hydrogen peroxide as the in situ bleaching source, and several commercial carbamide peroxide bleaching gels. Control treatments included placebo gels and an untreated group. Crest Whitestrips bleaching included treatment exposures simulating recommended clinical exposures (14 hours), along with excess bleaching simulating exposure to five times suggested Crest Whitestrips use. At the conclusion of treatments, surface microhardness measures and surface morphological assessments with standard and variable pressure (VP-) SEMs were conducted to assess the effects of bleaching exposure on the surface morphology and structural integrity of the restoratives. Surface microhardness and SEM measures revealed no significant deleterious effects on the restoration surfaces from Whitestrips gels. These results confirm that tooth bleaching from the selected commercial hydrogen peroxide or carbamide peroxide bleaching systems does not produce changes in surface morphology or microhardness of common dental restorative materials. These results support the clinical safety of the selected commercial bleaching systems to the oral environment, matching results obtained from long-term use of these ingredients applied in dental offices and available in commercial formulations.

  20. The 2014 coral bleaching and freshwater flood events in Kāneʻohe Bay, Hawaiʻi

    Science.gov (United States)

    Jokiel, Paul L.; Rodgers, Kuʻulei S.

    2015-01-01

    Until recently, subtropical Hawaiʻi escaped the major bleaching events that have devastated many tropical regions, but the continued increases in global long-term mean temperatures and the apparent ending of the Pacific Decadal Oscillation (PDO) cool phase have increased the risk of bleaching events. Climate models and observations predict that bleaching in Hawaiʻi will occur with increasing frequency and increasing severity over future decades. A freshwater “kill” event occurred during July 2014 in the northern part of Kāneʻohe Bay that reduced coral cover by 22.5% in the area directly impacted by flooding. A subsequent major bleaching event during September 2014 caused extensive coral bleaching and mortality throughout the bay and further reduced coral cover in the freshwater kill area by 60.0%. The high temperature bleaching event only caused a 1.0% reduction in live coral throughout the portion of the bay not directly impacted by the freshwater event. Thus, the combined impact of the low salinity event and the thermal bleaching event appears to be more than simply additive. The temperature regime during the September 2014 bleaching event was analogous in duration and intensity to that of the large bleaching event that occurred previously during August 1996, but resulted in a much larger area of bleaching and coral mortality. Apparently seasonal timing as well as duration and magnitude of heating is important. Coral spawning in the dominant coral species occurs early in the summer, so reservoirs of stored lipid in the corals had been depleted by spawning prior to the September 2014 event. Warm months above 27 °C result in lower coral growth and presumably could further decrease lipid reserves, leading to a bleaching event that was more severe than would have happened if the high temperatures occurred earlier in the summer. Hawaiian reef corals decrease skeletal growth at temperatures above 27 °C, so perhaps the “stress period” actually started long

  1. The 2014 coral bleaching and freshwater flood events in Kāneʻohe Bay, Hawaiʻi

    Directory of Open Access Journals (Sweden)

    Keisha D. Bahr

    2015-08-01

    Full Text Available Until recently, subtropical Hawaiʻi escaped the major bleaching events that have devastated many tropical regions, but the continued increases in global long-term mean temperatures and the apparent ending of the Pacific Decadal Oscillation (PDO cool phase have increased the risk of bleaching events. Climate models and observations predict that bleaching in Hawaiʻi will occur with increasing frequency and increasing severity over future decades. A freshwater “kill” event occurred during July 2014 in the northern part of Kāneʻohe Bay that reduced coral cover by 22.5% in the area directly impacted by flooding. A subsequent major bleaching event during September 2014 caused extensive coral bleaching and mortality throughout the bay and further reduced coral cover in the freshwater kill area by 60.0%. The high temperature bleaching event only caused a 1.0% reduction in live coral throughout the portion of the bay not directly impacted by the freshwater event. Thus, the combined impact of the low salinity event and the thermal bleaching event appears to be more than simply additive. The temperature regime during the September 2014 bleaching event was analogous in duration and intensity to that of the large bleaching event that occurred previously during August 1996, but resulted in a much larger area of bleaching and coral mortality. Apparently seasonal timing as well as duration and magnitude of heating is important. Coral spawning in the dominant coral species occurs early in the summer, so reservoirs of stored lipid in the corals had been depleted by spawning prior to the September 2014 event. Warm months above 27 °C result in lower coral growth and presumably could further decrease lipid reserves, leading to a bleaching event that was more severe than would have happened if the high temperatures occurred earlier in the summer. Hawaiian reef corals decrease skeletal growth at temperatures above 27 °C, so perhaps the “stress period

  2. A comparison between boat-based and diver-based methods for quantifying coral bleaching

    Science.gov (United States)

    Zawada, David G.; Ruzicka, Rob; Colella, Michael A.

    2015-01-01

    Recent increases in both the frequency and severity of coral bleaching events have spurred numerous surveys to quantify the immediate impacts and monitor the subsequent community response. Most of these efforts utilize conventional diver-based methods, which are inherently time-consuming, expensive, and limited in spatial scope unless they deploy large teams of scientifically-trained divers. In this study, we evaluated the effectiveness of the Along-Track Reef Imaging System (ATRIS), an automated image-acquisition technology, for assessing a moderate bleaching event that occurred in the summer of 2011 in the Florida Keys. More than 100,000 images were collected over 2.7 km of transects spanning four patch reefs in a 3-h period. In contrast, divers completed 18, 10-m long transects at nine patch reefs over a 5-day period. Corals were assigned to one of four categories: not bleached, pale, partially bleached, and bleached. The prevalence of bleaching estimated by ATRIS was comparable to the results obtained by divers, but only for corals > 41 cm in size. The coral size-threshold computed for ATRIS in this study was constrained by prevailing environmental conditions (turbidity and sea state) and, consequently, needs to be determined on a study-by-study basis. Both ATRIS and diver-based methods have innate strengths and weaknesses that must be weighed with respect to project goals.

  3. Biodiesel production from residual oils recovered from spent bleaching earth

    International Nuclear Information System (INIS)

    Huang, Yi-Pin; Chang, James I.

    2010-01-01

    This work was to study technical and economic feasibilities of converting residual oils recovered from spent bleaching earth generated at soybean oil refineries into useable biodiesel. Experimental results showed that fatty acids in the SBE residual oil were hexadecenoic acid (58.19%), stearic acid (21.49%) and oleic acid (20.32%), which were similar to those of vegetable oils. The methyl ester conversion via a transesterification process gave a yield between 85 and 90%. The biodiesel qualities were in reasonable agreement with both EN 14214 and ASTM D6751 standards. A preliminary financial analysis showed that the production cost of biodiesel from SBE oils was significantly lower than the pre-tax price of fossil diesel or those made of vegetable oils or waste cooking oils. The effects of the crude oil price and the investment on the production cost and the investment return period were also conducted. The result showed that the investment would return faster at higher crude oil price. (author)

  4. Reuse of spent bleaching earth by polymerisation of residual organics.

    Science.gov (United States)

    Beshara, Abdelhamid; Cheeseman, Christopher R

    2014-10-01

    Spent bleaching earth (SBE) is a waste generated by the edible oil industry that currently has limited options for beneficial reuse. In excess of ∼2 million tonnes per year of SBE is generated world-wide with major quantities available in the middle-east where significant volumes of edible oils are produced. Low pressure compaction followed by heat treatment at 150°C causes polymerisation of the residual organic components in SBE and this produces monolithic samples with high unconfined compressive strengths (54MPa). SBE can therefore be used to manufacture novel clay blocks for use in construction that are bonded by polymerised vegetable oil. This represents a new, innovative and resource efficient application for SBE. In this research, commercial SBE has been characterised and the effects of key processing variables (temperature and compaction pressure) on the compressive strength, porosity and density of the SBE clay blocks are reported and the mechanisms responsible for strength development are discussed. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Effects of fluoride or nanohydroxiapatite on roughness and gloss of bleached teeth.

    Science.gov (United States)

    Pedreira De Freitas, Ana Carolina; Botta, Sérgio Brossi; Teixeira, Fernanda De Sá; Salvadori, Maria Cecília Barbosa Silveira; Garone-Netto, Narciso

    2011-12-01

    The aim of this study was to describe roughness and gloss alterations of enamel after treatment with 38% hydrogen peroxide (HP) and after polishing with 2% neutral sodium fluoride (SF) or a dental tooth paste containing nanohydroxiapatite particles (nHA) using power spectral density (PSD) description, roughness parameters (Ra, RMS, and Z range) and gloss analysis. An atomic force microscope (AFM) and a spectrophotometer were used to analyze eighteen specimens of upper incisors. After initial analyses, all specimens were bleached with 38% HP for 135 min. The specimens were analyzed after bleaching. Nine specimens were polished with SF (Group Fluor) and the other nine specimens were polished with nHA (Group nHA), then all specimens were analyzed after polishing. Roughness and gloss were analyzed with ANOVA and Tukey's t-test. No statistical difference was found for Ra and RMS among initial, after bleaching and after polishing in both groups. For Z range, Group nHA showed a significant decrease after polishing. Bleaching with 38% HP did not increase the PSD in the spatial frequency of the visible light spectrum range in both groups. After polishing, nHA group showed a decrease in PSD for all morphological wavelengths. Gloss did not show statistical difference after bleaching in both groups. Gloss showed significant increase after polishing with nHA. bleaching treatment with 38% HP didn't alter enamel surface roughness or gloss. PSD analyses were very suitable to identifying the morphological changes on the surfaces. Copyright © 2011 Wiley Periodicals, Inc.

  6. The whitening effect of bleaching agents on tetracycline-stained rat teeth.

    Science.gov (United States)

    Shin, D H; Summitt, J B

    2002-01-01

    This study compared the whitening effect of three bleaching agents on the teeth of rats and demonstrated differences in bleaching where dentin was exposed or enamel was thin. Thirty Albino rats were peritoneally injected with tetracycline solution daily for two weeks. Thirty-two disc-shaped specimens were cut from the crowns of incisors removed from sacrificed rats and were irradiated with UV light for 16 hours. Sections were stored in saline. Eight sections served as controls and were not bleached. Three bleaching agents (Opalescence, Rembrandt and Nite White) were applied to eight specimens each, five times a day for two weeks, and images of the sections were recorded at the following times: before bleaching (baseline), day 1, day 3, day 5, day 7, day 9, day 11 and day 14. Mean colors to demonstrate any change (deltaE) from baseline for each time period were as follows: control-9.78 (baseline), 9.17, 9.36, 9.65, 9.40, 9.99, 10.57, 11.36; Opalescence-10.08, (baseline) 7.63, 6.72, 6.04, 5.10, 4.87, 4.89, 4.27; Rembrandt-9.83 (baseline), 11.27, 9.55, 8.36, 7.75, 6.94, 7.11, 7.04; Nite White-10.44 (baseline), 9.92, 7.58, 6.80, 5.45, 5.05, 4.73, 4.01. All bleached teeth were lightened (p<.01). Another 56 tetracycline-stained rat incisors were UV irradiated for three days. Three different penetration depths were tested: penetration through lingual dentin and labial enamel (DN group), penetration through labial enamel only (RE group) and penetration through labial enamel covered with 1.0 mm human enamel (HE group). Specimens were bleached with Opalescence for one hour five times a day for one week or four weeks. A control group of unbleached teeth was also examined. Results (deltaE) were as follows: control--11.67; 1-week DN--13.55; 1-week RE--12.80; 1-week HE--12.07; 4-week DN--7.48; 4-week RE--7.50; 4-week HE--11.69. The color change in the 4-week DN and the 4-week RE groups showed the greatest reduction (p<.01).

  7. A comparative analysis of bleached and sound enamel structure through scanning electron microscopy and atomic force microscopy

    International Nuclear Information System (INIS)

    Saleem, A.; Kaleem, M.; Anwar, R.

    2015-01-01

    To analyze the effects of bleaching agent on enamel structure and to characterize the morphological and chemical changes in enamel due to bleaching. Study Design: Experimental study. Place and Duration of Study: School of Chemical and Material Engineering (SCME), NUST Islamabad from Feb to May 2013. Materials and Methods: Ten recently extracted pre molars between the 12-22 years age group were randomly assigned into two groups. Group one was a non-bleached control group with sound enamel. Group two was bleached with Everbrite In office tooth whitening system after specimen preparation, surface morphology was observed under SEM (scanned electron microscope) and AFM (Atomic force microscope). Results: The detrimental effects of hydrogen per-oxide on enamel were evident in bleached specimens under SEM, and AFM analysis. Conclusion: There were significant surface alterations found in the bleached specimens as compared to control group. However salivary buffering potentials could overcome the demineralizing effect of bleaching gel. (author)

  8. Bleaching of the post-IR IRSL signal from individual grains of K-feldspar: Implications for single-grain dating

    International Nuclear Information System (INIS)

    Smedley, R.K.; Duller, G.A.T.; Roberts, H.M.

    2015-01-01

    Post-IR IRSL (pIRIR) signals from K-feldspar grains measured at elevated temperatures are increasingly being used for dating sediments. Unfortunately the pIRIR signal from K-feldspars bleaches more slowly than other signals (e.g. OSL from quartz) upon exposure to daylight, leading to concerns about residual signals remaining at deposition. However, earlier studies have not assessed whether the pIRIR signal bleaches at the same rate in all feldspar grains. In this study laboratory bleaching experiments have been conducted and for the first time the results show that the rate at which the pIRIR signal from individual K-feldspar grains bleach varies. To determine whether grain-to-grain variability in bleaching rate has a dominant control on equivalent dose (D e ) distributions determined using single grains, analysis was undertaken on three samples with independent age control from different depositional environments (two aeolian and one glaciofluvial). The D e value determined from each grain was compared with the rate at which the pIRIR 225 signal from the grain bleaches. The bleaching rate of each grain was assessed by giving a 52 Gy dose and measuring the residual D e after bleaching for an hour in a solar simulator. There is no clear relationship between the rate at which the pIRIR 225 signal of an individual grain bleaches and the magnitude of its D e . It is concluded that variability in the bleaching rate of the pIRIR 225 signal from one grain to another does not appear to be a dominant control on single grain D e distributions. - Highlights: • The bleaching rate of the pIRIR signal from single K-feldspar grains was assessed. • The pIRIR 225 signal bleaches more rapidly than the pIRIR 290 signal. • pIRIR 225 and pIRIR 290 signals reach the same level after 4–20 h of bleaching. • The bleaching rate of the pIRIR signal varies from one grain to another. • Variable pIRIR bleaching rates do not control single-grain D e distributions

  9. Proteomic analysis of bleached and unbleached Acropora palmata, a threatened coral species of the Caribbean.

    Science.gov (United States)

    Ricaurte, Martha; Schizas, Nikolaos V; Ciborowski, Pawel; Boukli, Nawal M

    2016-06-15

    There has been an increase in the scale and frequency of coral bleaching around the world due mainly to changes in sea temperature. This may occur at large scales, often resulting in significant decline in coral coverage. In order to understand the molecular and cellular basis of the ever-increasing incidence of coral bleaching, we have undertaken a comparative proteomic approach with the endangered Caribbean coral Acropora palmata. Using a proteomic tandem mass spectrometry approach, we identified 285 and 321 expressed protein signatures in bleached and unbleached A. palmata colonies, respectively, in southwestern Puerto Rico. Overall the expression level of 38 key proteins was significantly different between bleached and unbleached corals. A wide range of proteins was detected and categorized, including transcription factors involved mainly in heat stress/UV responses, immunity, apoptosis, biomineralization, the cytoskeleton, and endo-exophagocytosis. The results suggest that for bleached A. palmata, there was an induced differential protein expression response compared with those colonies that did not bleach under the same environmental conditions. Published by Elsevier Ltd.

  10. Activities in department of energy hazardous and mixed waste defense waste management

    International Nuclear Information System (INIS)

    Eyman, L.D.

    1988-01-01

    In January 1986, the U.S. Department of Energy (DOE) Office of Assistant Secretary for Defense Programs (DP) created the Hazardous Waste and Remedial Actions Division within the Office of Defense Waste and Transportation Management. The Oak Ridge Operations Office (ORO) was assigned the responsibility for supporting DOE Headquarters (HQ) in planning nationally integrated activities for Resource Conservation and Recovery Act/Comprehensive Environmental Response, Compensation, and Liability Act/Superfund Amendments and Reauthorization Act (RCRA/CERCLA/SARA) compliance. In turn, ORO created the Hazardous Waste Remedial Actions Program Support Contractor Office (HAZWRAPSCO) to assist with the expanded lead assignment. The HAZWRAPSCO activities are currently supported by three distinct DOE-HQ funding elements: the Environmental Restoration Program, the Hazardous Waste Compliance Technology Program, and the Hazardous Waste Research and Development R and D Program. The Environmental Restoration Program is discussed in the paper, entitled The DOE Defense Program for Environmental Restoration

  11. Changes to Glazed Dental Ceramic Shade, Roughness, and Microhardness after Bleaching and Simulated Brushing.

    Science.gov (United States)

    Rodrigues, Carlos Roberto Teixeira; Turssi, Cecilia Pedroso; Amaral, Flávia Lucisano Botelho; Basting, Roberta Tarkany; França, Fabiana Mantovani Gomes

    2017-09-05

    To evaluate shade stability, surface roughness, microhardness, and compressive strength of a glazed feldspathic ceramic subjected to bleaching and simulated brushing. Eighty-eight glazed feldspathic ceramic specimens were made from microparticulate leucite and divided into eight groups (n = 10). The whitening products used were: Opalescence Trèswhite Supreme (Ultradent), Opalescence®\\ PF 15% (Ultradent), and Oral-B 3D White Whitestrips. All substances for whitening were used for 4 hours/day for a period of 14 days; the control group was not bleached. Next, half of the specimens were individually brushed. Microhardness and surface roughness data were subjected to three-way ANOVA and Tukey test. The diametrical tensile strength data were subjected to two-way ANOVA. The shade change data were analyzed using Kruskal-Wallis, Mann-Whitney, and the Student-Newman-Keuls test. The significance level was set at 5%. Glazed feldspathic ceramic surface microhardness was significantly affected by bleaching agents (p = 0.007). Initially, glazed ceramic microhardness was significantly higher than that observed after contact with the bleaching agents, whether or not brushing was performed. The specimens submitted to bleaching in preloaded trays presented lower surface roughness values after brushing (p = 0.037). The surface roughness was significantly lower in the brushed specimens (p = 0.044). The diametrical tensile strength was not significantly affected by the application of bleaching agents (p = 0.563) or by brushing (p = 0.477). When the specimens were brushed, however, shade change was significantly influenced by the bleaching agent used (p = 0.041). Bleaching agents associated with brushing cycles can alter surface properties and shade stability of glazed feldspathic ceramics, though such findings may not reflect the performance of unglazed feldspathic ceramics. © 2017 by the American College of Prosthodontists.

  12. Bleaching Gels Containing Calcium and Fluoride: Effect on Enamel Erosion Susceptibility

    Directory of Open Access Journals (Sweden)

    Alessandra B. Borges

    2012-01-01

    Full Text Available This in vitro study evaluated the effect of 35% hydrogen peroxide (HP bleaching gel modified or not by the addition of calcium and fluoride on enamel susceptibility to erosion. Bovine enamel samples (3 mm in diameter were divided into four groups (n=15 according to the bleaching agent: control—without bleaching (C; 35% hydrogen peroxide (HP; 35% HP with the addition of 2% calcium gluconate (HP + Ca; 35% HP with the addition of 0.6% sodium fluoride (HP + F. The bleaching gels were applied on the enamel surface for 40 min, and the specimens were subjected to erosive challenge with Sprite Zero and remineralization with artificial saliva for 5 days. Enamel wear was assessed using profilometry. The data were analyzed by ANOVA/ Tukey’s test (P<0.05. There were significant differences among the groups (P=0.009. The most enamel wear was seen for C (3.37±0.80 μm, followed by HP (2.89 ± 0.98 μm and HP + F (2.72 ± 0.64 μm. HP + Ca (2.31 ± 0.92 μm was the only group able to significantly reduce enamel erosion compared to C. The application of HP bleaching agent did not increase the enamel susceptibility to erosion. However, the addition of calcium gluconate to the HP gel resulted in reduced susceptibility of the enamel to erosion.

  13. STUDIES ON XYLANASE AND LACCASE ENZYMATIC PREBLEACHING TO REDUCE CHLORINE-BASED CHEMICALS DURING CEH AND ECF BLEACHING

    Directory of Open Access Journals (Sweden)

    Vasanta V. Thakur,

    2012-02-01

    Full Text Available The biobleaching efficiency of xylanase and laccase enzymes was studied on kraft pulps from wood and nonwood based raw materials employed in the Indian paper industry. Treatment of these pulps with xylanase enzyme could result in improved properties, showing 2.0% ISO gain in pulp brightness and/or reducing the demand of chlorine-based bleach chemicals by up to 15% with simultaneous reduction of 20 to 25% in AOX generation in bleach effluents. Further, mill-scale trial results revealed that enzymatic prebleaching can be successfully employed with xylanases to reach the same bleach boosting efficacy. Laccase bleaching was also studied on hardwood pulp at a pH around 8.0, where most of the pulp mills in India are operating, in contrast to earlier studies on laccase enzyme bleaching, which were conducted at acidic pHs, i.e. 4.0 to 5.0. In case of laccase bleaching, interesting results were found wherein a bleach-boosting effect was observed even at pH 8.0. Further studies carried out with HOBT as mediator in comparison to the commonly used and expensive ABTS laccase mediator system (LMS resulted in improvement of the bleaching efficiency with reduction in demand of chlorine dioxide by more than 35%. Potential for further reduction was indicated by the brightness gain, when compared with a control using the DE(pD bleach sequence.

  14. Physiological and biogeochemical traits of bleaching and recovery in the mounding species of coral Porites lobata: implications for resilience in mounding corals.

    Directory of Open Access Journals (Sweden)

    Stephen J Levas

    Full Text Available Mounding corals survive bleaching events in greater numbers than branching corals. However, no study to date has determined the underlying physiological and biogeochemical trait(s that are responsible for mounding coral holobiont resilience to bleaching. Furthermore, the potential of dissolved organic carbon (DOC as a source of fixed carbon to bleached corals has never been determined. Here, Porites lobata corals were experimentally bleached for 23 days and then allowed to recover for 0, 1, 5, and 11 months. At each recovery interval a suite of analyses were performed to assess their recovery (photosynthesis, respiration, chlorophyll a, energy reserves, tissue biomass, calcification, δ(13C of the skeletal, δ(13C, and δ(15N of the animal host and endosymbiont fractions. Furthermore, at 0 months of recovery, the assimilation of photosynthetically acquired and zooplankton-feeding acquired carbon into the animal host, endosymbiont, skeleton, and coral-mediated DOC were measured via (13C-pulse-chase labeling. During the first month of recovery, energy reserves and tissue biomass in bleached corals were maintained despite reductions in chlorophyll a, photosynthesis, and the assimilation of photosynthetically fixed carbon. At the same time, P. lobata corals catabolized carbon acquired from zooplankton and seemed to take up DOC as a source of fixed carbon. All variables that were negatively affected by bleaching recovered within 5 to 11 months. Thus, bleaching resilience in the mounding coral P. lobata is driven by its ability to actively catabolize zooplankton-acquired carbon and seemingly utilize DOC as a significant fixed carbon source, facilitating the maintenance of energy reserves and tissue biomass. With the frequency and intensity of bleaching events expected to increase over the next century, coral diversity on future reefs may favor not only mounding morphologies but species like P. lobata, which have the ability to utilize heterotrophic

  15. Bleaching susceptibility and recovery of Colombian Caribbean corals in response to water current exposure and seasonal upwelling.

    Directory of Open Access Journals (Sweden)

    Elisa Bayraktarov

    Full Text Available Coral bleaching events are globally occurring more frequently and with higher intensity, mainly caused by increases in seawater temperature. In Tayrona National Natural Park (TNNP in the Colombian Caribbean, local coral communities are subjected to seasonal wind-triggered upwelling events coinciding with stronger water currents depending on location. This natural phenomenon offers the unique opportunity to study potential water current-induced mitigation mechanisms of coral bleaching in an upwelling influenced region. Therefore, coral bleaching susceptibility and recovery patterns were compared during a moderate and a mild bleaching event in December 2010 and 2011, and at the end of the subsequent upwelling periods at a water current-exposed and -sheltered site of an exemplary bay using permanent transect and labeling tools. This was accompanied by parallel monitoring of key environmental variables. Findings revealed that in 2010 overall coral bleaching before upwelling was significantly higher at the sheltered (34% compared to the exposed site (8%. Whereas 97% of all previously bleached corals at the water current-exposed site had recovered from bleaching by April 2011, only 77% recovered at the sheltered site, but 12% had died there. In December 2011, only mild bleaching (<10% at both sites was observed, but corals recovered significantly at both sites in the course of upwelling. No differences in water temperatures between sites occurred, but water current exposure and turbidity were significantly higher at the exposed site, suggesting that these variables may be responsible for the observed site-specific mitigation of coral bleaching. This indicates the existence of local resilience patterns against coral bleaching in Caribbean reefs.

  16. Bleaching susceptibility and recovery of Colombian Caribbean corals in response to water current exposure and seasonal upwelling.

    Science.gov (United States)

    Bayraktarov, Elisa; Pizarro, Valeria; Eidens, Corvin; Wilke, Thomas; Wild, Christian

    2013-01-01

    Coral bleaching events are globally occurring more frequently and with higher intensity, mainly caused by increases in seawater temperature. In Tayrona National Natural Park (TNNP) in the Colombian Caribbean, local coral communities are subjected to seasonal wind-triggered upwelling events coinciding with stronger water currents depending on location. This natural phenomenon offers the unique opportunity to study potential water current-induced mitigation mechanisms of coral bleaching in an upwelling influenced region. Therefore, coral bleaching susceptibility and recovery patterns were compared during a moderate and a mild bleaching event in December 2010 and 2011, and at the end of the subsequent upwelling periods at a water current-exposed and -sheltered site of an exemplary bay using permanent transect and labeling tools. This was accompanied by parallel monitoring of key environmental variables. Findings revealed that in 2010 overall coral bleaching before upwelling was significantly higher at the sheltered (34%) compared to the exposed site (8%). Whereas 97% of all previously bleached corals at the water current-exposed site had recovered from bleaching by April 2011, only 77% recovered at the sheltered site, but 12% had died there. In December 2011, only mild bleaching (corals recovered significantly at both sites in the course of upwelling. No differences in water temperatures between sites occurred, but water current exposure and turbidity were significantly higher at the exposed site, suggesting that these variables may be responsible for the observed site-specific mitigation of coral bleaching. This indicates the existence of local resilience patterns against coral bleaching in Caribbean reefs.

  17. Hanford immobilized low-activity tank waste performance assessment

    International Nuclear Information System (INIS)

    Mann, F.M.

    1998-01-01

    The Hanford Immobilized Low-Activity Tank Waste Performance Assessment examines the long-term environmental and human health effects associated with the planned disposal of the vitrified low-level fraction of waste presently contained in Hanford Site tanks. The tank waste is the by-product of separating special nuclear materials from irradiated nuclear fuels over the past 50 years. This waste has been stored in underground single and double-shell tanks. The tank waste is to be retrieved, separated into low and high-activity fractions, and then immobilized by private vendors. The US Department of Energy (DOE) will receive the vitrified waste from private vendors and plans to dispose of the low-activity fraction in the Hanford Site 200 East Area. The high-level fraction will be stored at Hanford until a national repository is approved. This report provides the site-specific long-term environmental information needed by the DOE to issue a Disposal Authorization Statement that would allow the modification of the four existing concrete disposal vaults to provide better access for emplacement of the immobilized low-activity waste (ILAW) containers; filling of the modified vaults with the approximately 5,000 ILAW containers and filler material with the intent to dispose of the containers; construction of the first set of next-generation disposal facilities. The performance assessment activity will continue beyond this assessment. The activity will collect additional data on the geotechnical features of the disposal sites, the disposal facility design and construction, and the long-term performance of the waste. Better estimates of long-term performance will be produced and reviewed on a regular basis. Performance assessments supporting closure of filled facilities will be issued seeking approval of those actions necessary to conclude active disposal facility operations. This report also analyzes the long-term performance of the currently planned disposal system as a basis

  18. Hanford immobilized low-activity tank waste performance assessment

    Energy Technology Data Exchange (ETDEWEB)

    Mann, F.M.

    1998-03-26

    The Hanford Immobilized Low-Activity Tank Waste Performance Assessment examines the long-term environmental and human health effects associated with the planned disposal of the vitrified low-level fraction of waste presently contained in Hanford Site tanks. The tank waste is the by-product of separating special nuclear materials from irradiated nuclear fuels over the past 50 years. This waste has been stored in underground single and double-shell tanks. The tank waste is to be retrieved, separated into low and high-activity fractions, and then immobilized by private vendors. The US Department of Energy (DOE) will receive the vitrified waste from private vendors and plans to dispose of the low-activity fraction in the Hanford Site 200 East Area. The high-level fraction will be stored at Hanford until a national repository is approved. This report provides the site-specific long-term environmental information needed by the DOE to issue a Disposal Authorization Statement that would allow the modification of the four existing concrete disposal vaults to provide better access for emplacement of the immobilized low-activity waste (ILAW) containers; filling of the modified vaults with the approximately 5,000 ILAW containers and filler material with the intent to dispose of the containers; construction of the first set of next-generation disposal facilities. The performance assessment activity will continue beyond this assessment. The activity will collect additional data on the geotechnical features of the disposal sites, the disposal facility design and construction, and the long-term performance of the waste. Better estimates of long-term performance will be produced and reviewed on a regular basis. Performance assessments supporting closure of filled facilities will be issued seeking approval of those actions necessary to conclude active disposal facility operations. This report also analyzes the long-term performance of the currently planned disposal system as a basis

  19. Wastes Characterisation from Foundry Activities on European Level

    International Nuclear Information System (INIS)

    Andres, I.; Ruiz, C.; Ibanez, R.; Viguri, J.; Irabien, A.

    1999-01-01

    This work presents The results of the eco toxicological characterisation of 22 defined wastes from steel foundry activities. The wastes have been selected from three processes, steel mill (smelting). sand casting and cleaning and finishing of steel products,with the common characteristics of represent an important industrial activity in the area and generated the wastes considered in this study. The eco toxicological characterisation obtained applying the Spanish regulations on hazardous waste is compared to the hazardous attributions considered by the European Union in order to characterise a waste as hazardous (non hazardous). The results allow to conclude that a acceptable concordance between both methodologies is reached and remark the need to split the broad generic types of wastes given by the Spanish regulation (Eco toxic / non eco toxic) into clearly identifiable specific types of waste

  20. Evaluation of several clinical parameters after bleaching with hydrogen peroxide at different concentrations: A randomized clinical trial.

    Science.gov (United States)

    Lima, Suellen Nogueira Linares; Ribeiro, Izabella Santos; Grisotto, Marcos Augusto; Fernandes, Elizabeth Soares; Hass, Viviane; de Jesus Tavarez, Rudys Rodolfo; Pinto, Shelon Cristina Souza; Lima, Darlon Martins; Loguercio, Alessandro D; Bandeca, Matheus Coelho

    2018-01-01

    This randomized double-blind clinical trial compared tooth sensitivity (TS), bleaching efficacy, and cytokine levels after applying in-office bleaching treatments containing 15% and 35% hydrogen peroxide (HP15% and HP35%, respectively). Twenty-five volunteers were randomly assigned to receive HP15% or HP35% treatment. The bleaching agent was applied in three 15-min applications per session. Two bleaching sessions were separated by a 1-week interval. The participants scored TS using a visual analog scale and numerical rating scale. Bleaching efficacy was determined by subjective and objective methods. Gingival crevicular fluid was collected from three jaws sites per patient for the analysis of fluid volume. Flow cytometry was used to analyze gingival crevicular fluid levels of interleukin (IL)-1β, IL-2, IL-4, IL-6, IL-10, tumor necrosis factor, and interferon-gamma. All measurements were obtained before and after bleaching. All data were statistically analyzed (α=0.05). The absolute risk and intensity of TS was higher for HP35% than for HP15% (p>0.002). One month post-bleaching, HP35% produced more bleaching than HP15% (p=0.02). However patient perception (p=0.06) and patient satisfaction (p=0.53) with regard to bleaching were not significantly different. No significant differences existed in the gingival fluid volume (p>0.38) or in any cytokine level (p>0.05) for either HP concentration. Treatment: with HP35% is more effective than HP15%, but generates a greater risk and intensity of TS. No inflammatory changes occurred despite the difference in the HP concentrations. Hydrogen peroxide at a lower concentration (e.g., 15%) should be considered a good treatment alternative for in-office bleaching because the higher concentration for in-office bleaching generates a greater risk and intensity of TS for patients. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. The effect of enamel bleaching on the shear bond strengths of metal and ceramic brackets.

    Science.gov (United States)

    Oztaş, E; Bağdelen, G; Kiliçoğlu, H; Ulukapi, H; Aydin, I

    2012-04-01

    The aim of this study was to evaluate the effects of bleaching and delayed bonding on the shear bond strengths of metal and ceramic brackets bonded with light and chemically cure composite resin to human enamel. One hundred and twenty extracted human premolar teeth were randomly divided into three groups of 40 each. The first two groups were bleached with 20 per cent carbamide peroxide (CP) at-home bleaching agent. No bleaching procedures were applied to the third group and served as control. The first two and control groups were divided into equal subgroups according to different adhesive-bracket combinations. Specimens in group 1 (n = 40) were bonded 24 hours after bleaching process was completed while the specimens in group 2 (n = 40) were bonded 14 days after. The specimens in all groups were debonded with a Universal testing machine while the modified adhesive remnant index was used to evaluate fracture properties. No statistically significant differences were found between the shear bond strengths of metal and ceramic brackets bonded to bleached enamel after 24 hours, 14 days, and unbleached enamel with light or chemical cure adhesives (P > 0.05). The mode of failure was mostly at the bracket/adhesive interface and cohesive failures within the resin were also observed. Our findings indicated that at-home bleaching agents that contain 20 per cent CP did not significantly affect the shear bond strength of metal and ceramic orthodontic brackets to enamel when bonding is performed 24 hours or 14 days after bleaching.

  2. Colorimeter and scanning electron microscopy analysis of teeth submitted to internal bleaching.

    Science.gov (United States)

    Martin-Biedma, Benjamin; Gonzalez-Gonzalez, Teresa; Lopes, Manuela; Lopes, Luis; Vilar, Rui; Bahillo, José; Varela-Patiño, Purificación

    2010-02-01

    This in vitro study compared the tooth color and the ultrastructure of internal dental tissues before and after internal bleaching. Sodium perborate was placed in the pulp chamber of endodontically treated molars and sealed with intermediate restorative material. The test samples were stored in a physiologic solution, and the bleaching agent was replaced every 7 days. A control group was used. After 1 month, the colors of the test and control samples were measured with a colorimeter, and the internal surfaces were observed under field emission scanning electron microscopy (FESEM). Statistically significant differences were found between the test and control sample colors. The FESEM ultrastructure analysis of the internal enamel and dentin surfaces did not show any changes after the internal bleaching. The results of the present study show that sodium perborate is effective in bleaching nonvital teeth and does not produce ultrastructural changes in the dental tissues. Copyright 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  3. Evaluation of antioxidant potential of Artocarpus heterophyllus L. J33 variety fruit waste from different extraction methods and identification of phenolic constituents by LCMS.

    Science.gov (United States)

    Daud, Mohd Nazrul Hisham; Fatanah, Dian Nashiela; Abdullah, Noriham; Ahmad, Rohaya

    2017-10-01

    Artocarpus heterophyllus J33 (AhJ33) fruit is a popular and valuable jackfruit variety in Malaysia. For export, the pulp has to be separated from the skin which is usually discarded. Hence, the conversion of the fruit waste to food products with economic value needs to be explored utilizing the waste to wealth concept. This paper reports the evaluation of antioxidant potential of AhJ33 fruit waste (rind and rachis) extracts from three different extraction methods (maceration, percolation and Soxhlet). The antioxidant potential was assessed by DPPH radical scavenging, FRAP and β-carotene bleaching assays. The total phenolic and total flavonoid contents were estimated by TPC and the TFC assays. For both rind and rachis, the maceration technique yielded extracts with the strongest antioxidant activities which correlated with the highest TPC and TFC values. TOF LCMS analyses identified two phenolic acids as the major constituents responsible for the antioxidant activity of the active extracts. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Effects of light irradiation on bleaching by a 3.5% hydrogen peroxide solution containing titanium dioxide

    International Nuclear Information System (INIS)

    Suemori, T; Kato, J; Nakazawa, T; Akashi, G; Igarashi, A; Hirai, Y; Kumagai, Y; Kurata, H

    2008-01-01

    A low-concentration hydrogen peroxide solution containing titanium dioxide as a photocatalyst has attracted attention as a safe office bleaching agent. In this study, the influence of different kinds of light on the bleaching effect of this agent was examined. The bleaching agent was applied to hematoporphyrin-stained paper strips that were then irradiated with a 405-nm diode laser (800 mW/cm 2 ), a halogen lamp (720 mW/cm 2 ), or an LED (835 mW/cm 2 ) for 5 minutes. The color was measured spectrophotometrically before treatment and every 30 seconds thereafter, and the effects of bleaching on the strip were assessed using the CIE 1976 L * a * b * color coordinate system. Of the three different irradiation conditions, 405-nm laser irradiation gave the strongest bleaching effect with 3.5% hydrogen peroxide containing titanium dioxide. The laser provides strong irradiance at 405 nm, which corresponds to the absorption range of the bleaching agent, and consequently the largest effect was obtained

  5. Contrasting patterns of changes in abundance following a bleaching event between juvenile and adult scleractinian corals

    Science.gov (United States)

    Álvarez-Noriega, Mariana; Baird, Andrew H.; Bridge, Tom C. L.; Dornelas, Maria; Fontoura, Luisa; Pizarro, Oscar; Precoda, Kristin; Torres-Pulliza, Damaris; Woods, Rachael M.; Zawada, Kyle; Madin, Joshua S.

    2018-06-01

    Coral bleaching events have caused extensive mortality on reefs around the world. Juvenile corals are generally less affected by bleaching than their conspecific adults and therefore have the potential to buffer population declines and seed recovery. Here, we use juvenile and adult abundance data at 20 sites encircling Lizard Island, Great Barrier Reef, before and after the 2016 bleaching event to quantify: (1) correlates of changes in juvenile abundance following a bleaching event; (2) differences in susceptibility to extreme thermal stress between juveniles and adults. Declines in juvenile abundance were lower at sites closer to the 20-m-depth contour and higher for Acropora and Pocillopora juveniles than for other taxa. Juveniles of Acropora and Goniastrea were less susceptible to bleaching than adults, but the opposite was true for Pocillopora spp. and taxa in the family Merulinidae. Our results indicate that the potential of the juvenile life stage to act as a buffer during bleaching events is taxon-dependent.

  6. Permitting plan for the immobilized low-activity waste project

    International Nuclear Information System (INIS)

    Deffenbaugh, M.L.

    1997-01-01

    This document addresses the environmental permitting requirements for the transportation and interim storage of the Immobilized Low-Activity Waste (ILAW) produced during Phase 1 of the Hanford Site privatization effort. Tri-Party Agreement (TPA) Milestone M-90 establishes a new major milestone, and associated interim milestones and target dates, governing acquisition and/or modification of facilities necessary for: (1) interim storage and disposal of Tank Waste Remediation Systems (TWRS) immobilized low-activity tank waste (ILAW) and (2) interim storage of TWRS immobilized HLW (IHLW) and other canistered high-level waste forms. Low-activity waste (LAW), low-level waste (LLW), and high-level waste (HLW) are defined by the TWRS, Hanford Site, Richland, Washington, Final Environmental Impact Statement (EIS) DOE/EIS-0189, August 1996 (TWRS, Final EIS). By definition, HLW requires permanent isolation in a deep geologic repository. Also by definition, LAW is ''the waste that remains after separating from high-level waste as much of the radioactivity as is practicable that when solidified may be disposed of as LLW in a near-surface facility according to the NRC regulations.'' It is planned to store/dispose of (ILAW) inside four empty vaults of the five that were originally constructed for the Group Program. Additional disposal facilities will be constructed to accommodate immobilized LLW packages produced after the Grout Vaults are filled. The specifications for performance of the low-activity vitrified waste form have been established with strong consideration of risk to the public. The specifications for glass waste form performance are being closely coordinated with analysis of risk. RL has pursued discussions with the NRC for a determination of the classification of the Hanford Site's low-activity tank waste fraction. There is no known RL action to change law with respect to onsite disposal of waste

  7. Is climate change triggering coral bleaching in tropical reef?

    Digital Repository Service at National Institute of Oceanography (India)

    Kalyan, De; Sautya, S.; Mote, S.; Tsering, L.; Patil, V.; Nagesh, R.; Ingole, B.S.

    established a herbarium at the Marine Algal Re- search Station, Mandapam Camp in April 2015. The old marine algal herbarium collection has been refurbished and des- ignated as reference repository at the na- tional level. This unique facility holds over... assessment of coral bleaching. Four belt transects (50 m  2 m) were deployed2 at a depth of 3–6 m, covering a total area of 400 m2 each of the sub-tidal reef flat (Figure 1). We have estimated mean bleaching of 15% coral colonies in the area sur...

  8. Opposite latitudinal gradients in projected ocean acidification and bleaching impacts on coral reefs.

    Science.gov (United States)

    van Hooidonk, Ruben; Maynard, Jeffrey Allen; Manzello, Derek; Planes, Serge

    2014-01-01

    Coral reefs and the services they provide are seriously threatened by ocean acidification and climate change impacts like coral bleaching. Here, we present updated global projections for these key threats to coral reefs based on ensembles of IPCC AR5 climate models using the new Representative Concentration Pathway (RCP) experiments. For all tropical reef locations, we project absolute and percentage changes in aragonite saturation state (Ωarag) for the period between 2006 and the onset of annual severe bleaching (thermal stress >8 degree heating weeks); a point at which it is difficult to believe reefs can persist as we know them. Severe annual bleaching is projected to start 10-15 years later at high-latitude reefs than for reefs in low latitudes under RCP8.5. In these 10-15 years, Ωarag keeps declining and thus any benefits for high-latitude reefs of later onset of annual bleaching may be negated by the effects of acidification. There are no long-term refugia from the effects of both acidification and bleaching. Of all reef locations, 90% are projected to experience severe bleaching annually by 2055. Furthermore, 5% declines in calcification are projected for all reef locations by 2034 under RCP8.5, assuming a 15% decline in calcification per unit of Ωarag. Drastic emissions cuts, such as those represented by RCP6.0, result in an average year for the onset of annual severe bleaching that is ~20 years later (2062 vs. 2044). However, global emissions are tracking above the current worst-case scenario devised by the scientific community, as has happened in previous generations of emission scenarios. The projections here for conditions on coral reefs are dire, but provide the most up-to-date assessment of what the changing climate and ocean acidification mean for the persistence of coral reefs. © 2013 John Wiley & Sons Ltd.

  9. Application of 10% Ascorbic Acid Improves Resin Shear Bond Stregth in Bleached Dentin

    Directory of Open Access Journals (Sweden)

    Kamizar Kamizar

    2014-10-01

    Full Text Available Normal 0 false false false IN X-NONE X-NONE MicrosoftInternetExplorer4 Restoration of the teeth immediately after bleaching with H2O2 35% is contraindicated due to the remnants of free radical that will stay inside dentin for 2-3 weeks which will compromise the adhesiveness of composite resin. Objective: The aim of this study was to evaluate the influence of 10% ascorbic acid on shear bond strength of composite placed on bleached dentin. Methods:Twenty seven samples were divided equally into three groups. Group 1: dentin was etched with 35% phosphoric acid; Group 2: dentin was bleached with 35% H2O2 followed by etching with 35% phosphoric acid; Group 3: dentin was bleached with 35% H2O2, followed by application of 10% ascorbic acid and etched with 35% phosphoric acid. All samples were then stored at 370C for 24 hours. The Universal Testing Machine was used to measure shear bond strength and the results were analyzed with Kruskal Wallis and Mann Whitney test. Results: After nine independent experiments, 10% ascorbic acid application on bleached dentin resulted in highest increased in bond stregth (56.04±11.06MPa compared to Group 2 (29.09±7.63MPa and Group 1 (25.55±2.22MPa and the difference was statistically significant (p<0.05. Conclusion: Application of 10% ascorbic acid to the bleached dentin improved the shear bond strength of resin composite.

  10. Estimating the effect of multiple environmental stressors on coral bleaching and mortality.

    Science.gov (United States)

    Welle, Paul D; Small, Mitchell J; Doney, Scott C; Azevedo, Inês L

    2017-01-01

    Coral cover has been declining in recent decades due to increased temperatures and environmental stressors. However, the extent to which different stressors contribute both individually and in concert to bleaching and mortality is still very uncertain. We develop and use a novel regression approach, using non-linear parametric models that control for unobserved time invariant effects to estimate the effects on coral bleaching and mortality due to temperature, solar radiation, depth, hurricanes and anthropogenic stressors using historical data from a large bleaching event in 2005 across the Caribbean. Two separate models are created, one to predict coral bleaching, and the other to predict near-term mortality. A large ensemble of supporting data is assembled to control for omitted variable bias and improve fit, and a significant improvement in fit is observed from univariate linear regression based on temperature alone. The results suggest that climate stressors (temperature and radiation) far outweighed direct anthropogenic stressors (using distance from shore and nearby human population density as a proxy for such stressors) in driving coral health outcomes during the 2005 event. Indeed, temperature was found to play a role ~4 times greater in both the bleaching and mortality response than population density across their observed ranges. The empirical models tested in this study have large advantages over ordinary-least squares-they offer unbiased estimates for censored data, correct for spatial correlation, and are capable of handling more complex relationships between dependent and independent variables. The models offer a framework for preparing for future warming events and climate change; guiding monitoring and attribution of other bleaching and mortality events regionally and around the globe; and informing adaptive management and conservation efforts.

  11. Estimating the effect of multiple environmental stressors on coral bleaching and mortality.

    Directory of Open Access Journals (Sweden)

    Paul D Welle

    Full Text Available Coral cover has been declining in recent decades due to increased temperatures and environmental stressors. However, the extent to which different stressors contribute both individually and in concert to bleaching and mortality is still very uncertain. We develop and use a novel regression approach, using non-linear parametric models that control for unobserved time invariant effects to estimate the effects on coral bleaching and mortality due to temperature, solar radiation, depth, hurricanes and anthropogenic stressors using historical data from a large bleaching event in 2005 across the Caribbean. Two separate models are created, one to predict coral bleaching, and the other to predict near-term mortality. A large ensemble of supporting data is assembled to control for omitted variable bias and improve fit, and a significant improvement in fit is observed from univariate linear regression based on temperature alone. The results suggest that climate stressors (temperature and radiation far outweighed direct anthropogenic stressors (using distance from shore and nearby human population density as a proxy for such stressors in driving coral health outcomes during the 2005 event. Indeed, temperature was found to play a role ~4 times greater in both the bleaching and mortality response than population density across their observed ranges. The empirical models tested in this study have large advantages over ordinary-least squares-they offer unbiased estimates for censored data, correct for spatial correlation, and are capable of handling more complex relationships between dependent and independent variables. The models offer a framework for preparing for future warming events and climate change; guiding monitoring and attribution of other bleaching and mortality events regionally and around the globe; and informing adaptive management and conservation efforts.

  12. Method to determine the activity concentration and total activity of radioactive waste

    International Nuclear Information System (INIS)

    Angeles C, A.

    2001-02-01

    A characteristic system of radioactive waste is described to determine the concentration of radionuclides activity and the total activity of bundles of radioactive waste. The system this integrated by three subsystems: - Elevator of drums. - Electromechanics. - Gamma spectroscopy. In the system it is analyzed waste of issuing gamma specifically, and this designed for materials of relative low density and it analyzes materials of cylindrical recipients

  13. Technical baseline description of high-level waste and low-activity waste feed mobilization and delivery

    International Nuclear Information System (INIS)

    Papp, I.G.

    1997-01-01

    This document is a compilation of information related to the high-level waste (HLW) and low-activity waste (LAW) feed staging, mobilization, and transfer/delivery issues. Information relevant to current Tank Waste Remediation System (TWRS) inventories and activities designed to feed the Phase I Privatization effort at the Hanford Site is included. Discussions on the higher level Phase II activities are offered for a perspective on the interfaces

  14. Anaphylaxis, contact urticaria, and allergic asthma caused by persulfates in hair bleaching products

    NARCIS (Netherlands)

    Hoekstra, Miriam; Schuttelaar, M.L.; Coenraads, P.J.

    2010-01-01

    Background: Persulfate salts are potent oxidizing agents in hair bleach products that accelerate the bleaching process. Ammonium and potassium persulfates may cause delayedtype and immediate skin reactions. Also allergic asthma and rhinitis have been described. Objectives: Ammonium and potassium

  15. Anaerobic biodegradability and toxicity of wastewaters from chlorine and total chlorine-free bleaching of eucalyptus kraft pulps.

    NARCIS (Netherlands)

    Vidal, G.; Soto, M.; Field, J.; Mendez-Pampin, R.; Lema, J.M.

    1997-01-01

    Chlorine bleaching effluents are problematic for anaerobic wastewater treatment due to their high methanogenic toxicity and low biodegradability. Presently, alternative bleaching processes are being introduced, such as elemental chlorine-free (ECF) and total chlorine-free (TCF) bleaching. The

  16. High-resolution modeling of thermal thresholds and environmental influences on coral bleaching for local and regional reef management.

    Science.gov (United States)

    Kumagai, Naoki H; Yamano, Hiroya

    2018-01-01

    Coral reefs are one of the world's most threatened ecosystems, with global and local stressors contributing to their decline. Excessive sea-surface temperatures (SSTs) can cause coral bleaching, resulting in coral death and decreases in coral cover. A SST threshold of 1 °C over the climatological maximum is widely used to predict coral bleaching. In this study, we refined thermal indices predicting coral bleaching at high-spatial resolution (1 km) by statistically optimizing thermal thresholds, as well as considering other environmental influences on bleaching such as ultraviolet (UV) radiation, water turbidity, and cooling effects. We used a coral bleaching dataset derived from the web-based monitoring system Sango Map Project, at scales appropriate for the local and regional conservation of Japanese coral reefs. We recorded coral bleaching events in the years 2004-2016 in Japan. We revealed the influence of multiple factors on the ability to predict coral bleaching, including selection of thermal indices, statistical optimization of thermal thresholds, quantification of multiple environmental influences, and use of multiple modeling methods (generalized linear models and random forests). After optimization, differences in predictive ability among thermal indices were negligible. Thermal index, UV radiation, water turbidity, and cooling effects were important predictors of the occurrence of coral bleaching. Predictions based on the best model revealed that coral reefs in Japan have experienced recent and widespread bleaching. A practical method to reduce bleaching frequency by screening UV radiation was also demonstrated in this paper.

  17. Climate change and coral reef bleaching: An ecological assessment of long-term impacts, recovery trends and future outlook

    Science.gov (United States)

    Baker, Andrew C.; Glynn, Peter W.; Riegl, Bernhard

    2008-12-01

    regenerating and recovering coral reefs have originated from broadcast spawning taxa with a potential for asexual growth, relatively long distance dispersal, successful settlement, rapid growth and a capacity for framework construction. Whether or not affected reefs can continue to function as before will depend on: (1) how much coral cover is lost, and which species are locally extirpated; (2) the ability of remnant and recovering coral communities to adapt or acclimatize to higher temperatures and other climatic factors such as reductions in aragonite saturation state; (3) the changing balance between reef accumulation and bioerosion; and (4) our ability to maintain ecosystem resilience by restoring healthy levels of herbivory, macroalgal cover, and coral recruitment. Bleaching disturbances are likely to become a chronic stress in many reef areas in the coming decades, and coral communities, if they cannot recover quickly enough, are likely to be reduced to their most hardy or adaptable constituents. Some degraded reefs may already be approaching this ecological asymptote, although to date there have not been any global extinctions of individual coral species as a result of bleaching events. Since human populations inhabiting tropical coastal areas derive great value from coral reefs, the degradation of these ecosystems as a result of coral bleaching and its associated impacts is of considerable societal, as well as biological concern. Coral reef conservation strategies now recognize climate change as a principal threat, and are engaged in efforts to allocate conservation activity according to geographic-, taxonomic-, and habitat-specific priorities to maximize coral reef survival. Efforts to forecast and monitor bleaching, involving both remote sensed observations and coupled ocean-atmosphere climate models, are also underway. In addition to these efforts, attempts to minimize and mitigate bleaching impacts on reefs are immediately required. If significant reductions in

  18. Novel Activated Carbons from Agricultural Wastes and their Characterization

    Directory of Open Access Journals (Sweden)

    S. Karthikeyan

    2008-01-01

    Full Text Available Solid waste disposal has become a major problem in India, Either it has to be disposed safely or used for the recovery of valuable materials as agricultural wastes like turmeric waste, ferronia shell waste, jatropha curcus seed shell waste, delonix shell waste and ipomea carnia stem. Therefore these wastes have been explored for the preparation of activated carbon employing various techniques. Activated carbons prepared from agricultural solid wastes by chemical activation processes shows excellent improvement in the surface characteristics. Their characterization studies such as bulk density, moisture content, ash content, fixed carbon content, matter soluble in water, matter soluble in acid, pH, decolourising power, phenol number, ion exchange capacity, ion content and surface area have been carried out to assess the suitability of these carbons as absorbents in the water and wastewater. For anionic dyes (reactive, direct, acid a close relationship between the surface area and surface chemical groups of the modified activated carbon and percentage of dye removal by adsorption can be observed. Cationic dyes large amount of surface chemical groups present in the sample (mainly carboxylic, anhydrides, lactones and phenols etc. are good anchoring sites for adsorption. The present study reveals the recovery of valuable adsorbents from readily and cheaply available agriculture wastes.

  19. Does a toothpaste containing blue covarine have any effect on bleached teeth? An in vitro, randomized and blinded study

    Directory of Open Access Journals (Sweden)

    Janaina Freitas BORTOLATTO

    2016-01-01

    Full Text Available Abstract The objective of this study was to analyze the effect of bleaching toothpastes, both conventional and those containing the new whitening agent Blue Covarine, on teeth previously bleached by conventional techniques (in-office and at-home. Squared bovine enamel/dentin blocks (6.0 x 6.0 x 2.0 mm were randomly distributed in 6 groups (n = 15, according to the technique used to bleach them (in-office: HP35%; at-home: PC10% and the type of bleaching toothpaste (none: control; Blue Covarine containing: BC; and without Blue Covarine: NBC. Experimental groups denominated HP35%, HP35%BC and HP35%NBC received in-office tooth bleaching before toothbrushing, and groups PC10%, PC10%BC and PC10%NBC were subjected to at-home tooth bleaching prior to toothbrushing. After bleaching treatment, groups HP35%BC, PC10%BC, HP35%NBC and PC10%NBC underwent daily tooth brushing in a brushing machine for 3 minutes (150 strokes/min, with a load of 375 g. Tooth color alteration was measured by reflectance spectroscopy (Vita EasyShade, Vident, Brea, CA, USA at: T0 (baseline – after in-office or at-home bleaching treatment; T1 – immediately after tooth brushing; T2 - 7 days and T3 - 14 days after tooth brushing. Data was analyzed by repeated measures mixed ANOVA and the Bonferroni post hoc test, with a significance level of 5%. Statistically significant differences were found between different experimental groups, evaluation times and for the interaction between them (p < 0.001. Tooth brushing using either bleaching toothpaste (conventional or with Blue Covarine showed no color alteration on teeth previously bleached by in-office and at-home tooth bleaching. The use of bleaching toothpastes on previously bleached teeth did not produce a color alteration.

  20. Resilience and climate change: lessons from coral reefs and bleaching in the Western Indian Ocean

    Science.gov (United States)

    Obura, David O.

    2005-05-01

    The impact of climate change through thermal stress-related coral bleaching on coral reefs of the Western Indian Ocean has been well documented and is caused by rising sea water temperatures associated with background warming trends and extreme climate events. Recent studies have identified a number of factors that may reduce the impact of coral bleaching and mortality at a reef or sub-reef level. However, there is little scientific consensus as yet, and it is unclear how well current science supports the immediate needs of management responses to climate change. This paper provides evidence from the Western Indian Ocean in support of recent hypotheses on coral and reef vulnerability to thermal stress that have been loosely termed 'resistance and resilience to bleaching'. The paper argues for a more explicit definition of terms, and identifies three concepts affecting coral-zooxanthellae holobiont and reef vulnerability to thermal stress previously termed 'resistance to bleaching': 'thermal protection', where some reefs are protected from the thermal conditions that induce bleaching and/or where local physical conditions reduce bleaching and mortality levels; 'thermal resistance', where individual corals bleach to differing degrees to the same thermal stress; and 'thermal tolerance', where individual corals suffer differing levels of mortality when exposed to the same thermal stress. 'Resilience to bleaching' is a special case of ecological resilience, where recovery following large-scale bleaching mortality varies according to ecological and other processes. These concepts apply across multiple levels of biological organization and temporal and spatial scales. Thermal resistance and tolerance are genetic properties and may interact with environmental protection properties resulting in phenotypic variation in bleaching and mortality of corals. The presence or absence of human threats and varying levels of reef management may alter the influence of the above factors

  1. Ecofriendly laccase-hydrogen peroxide/ultrasound-assisted bleaching of linen fabrics and its influence on dyeing efficiency.

    Science.gov (United States)

    Abou-Okeil, A; El-Shafie, A; El Zawahry, M M

    2010-02-01

    This study evaluates the bleaching efficiency of enzymatically scoured linen fabrics using a combined laccase-hydrogen peroxide bleaching process with and without ultrasonic energy, with the goal of obtaining fabrics with high whiteness levels, well preserved tensile strength and higher dye uptake. The effect of the laccase enzyme and the combined laccase-hydrogen peroxide bleaching process with and without ultrasound has been investigated with regard to whiteness value, tensile strength, dyeing efficiency and dyeing kinetics using both reactive and cationic dyes. The bleached linen fabrics were characterized using X-ray diffraction and by measuring tensile strength and lightness. The dyeing efficiency and kinetics were characterized by measuring dye uptake and colour fastness. The results indicated that ultrasound was an effective technique in the combined laccase-hydrogen peroxide bleaching process of linen fabrics. The whiteness values expressed as lightness of linen fabrics is enhanced by using ultrasonic energy. The measured colour strength values were found to be slightly better for combined laccase-hydrogen peroxide/ultrasound-assisted bleached fabrics than for combined laccase-hydrogen peroxide for both reactive and cationic dyes. The fastness properties of the fabrics dyed with reactive dye were better than those obtained when using cationic dye. The time/dye uptake isotherms were also enhanced when using combined laccase-hydrogen peroxide/ultrasound-assisted bleached fabric, which confirms the efficiency of ultrasound in the combined oxidative bleaching process. The dyeing rate constant, half-time of dyeing and dyeing efficiency have been calculated and discussed.

  2. Clarifications, guidelines and questions about the dental bleaching "associated" with orthodontic treatment

    Directory of Open Access Journals (Sweden)

    Alberto Consolaro

    2013-10-01

    Full Text Available With regard to the best moment for carrying out or recommending dental bleaching to orthodontic patients, some explanations and orientations are given in order to answers the following questions: 1 Why orthodontic treatment completion is considered the best opportunity for carrying out the procedure? 2 Why dental bleaching should not be performed immediately before orthodontic treatment? 3 If that would be possible at any special case, what would that be? 4 Why dental bleaching should not be performed during orthodontic treatment? 5 If that would be possible at any special case, what would that be? This article highlights why it is essential to protect both the mucosa and the cervical region, regardless of the moment when dental bleaching is performed, whether associated with orthodontic treatment or not. The "how", "why" and "if" of whether or not it is convenient to perform dental bleaching before orthodontic treatment are still a matter of clinical suggestion, as it is a procedure that is under analysis, empirical knowledge waiting for scientific proof or disproof! Although tooth enamel has adamantine fluid flowing within it, providing a specific metabolism that is peculiar to its own and which could scientifically explain and base the option of carrying out teeth whitening before and during orthodontic treatment, we must still be very careful.

  3. Optimization of extraction parameters on the antioxidant properties of banana waste.

    Science.gov (United States)

    Toh, Pui Yee; Leong, Fei Shan; Chang, Sui Kiat; Khoo, Hock Eng; Yim, Hip Seng

    2016-01-01

    Banana is grown worldwide and consumed as ripe fruit or used for culinary purposes. Peels form about 18-33% of the whole fruit and are discarded as a waste product. With a view to exploiting banana peel as a source of valuable compounds, this study was undertaken to evaluate the effect of different extraction parameters on the antioxidant activities of the industrial by-product of banana waste (peel). Influence of different extraction parameters such as types of solvent, percentages of solvent, and extraction times on total phenolic content (TPC) and antioxidant activity of mature and green peels of Pisang Abu (PA), Pisang Berangan (PB), and Pisang Mas (PM) were investigated. The best extraction parameters were initially selected based on different percentages of ethanol (0-100% v/v), extraction time (1-5 hr), and extraction temperature (25-60°C) for extraction of antioxidants in the banana peels. Total phenolic content (TPC) was evaluated using Folin-Ciocalteu reagent assay while antioxidant activities (AA) of banana peel were accessed by DPPH, ABTS, and β-carotene bleaching (BCB) assays at optimum extraction conditions. Based on different extraction solvents and percentages of solvents used, 70% and 90% of acetone had yielded the highest TPC for the mature and green PA peels, respectively; 90% of ethanol and methanol has yielded the highest TPC for the mature and green PB peels, respectively; while 90% ethanol for the mature and green PM peels. Similar extraction conditions were found for the antioxidant activities for the banana peel assessed using DPPH assay except for green PB peel, which 70% methanol had contributed to the highest AA. Highest TPC and AA were obtained by applying 4, 1, and 2 hrs extraction for the peels of PA, PB and PM, respectively. The best extraction conditions were also used for determination of AAs using ABTS and β-carotene bleaching assays. Therefore, the best extraction conditions used have given the highest TPC and AAs. By

  4. Optimization Of Bleaching Parameters By Whiteness Index And Bursting Strength Of Knitted Cotton Fabric

    Directory of Open Access Journals (Sweden)

    Abu Naser Md. Ahsanul Haque

    2015-04-01

    Full Text Available Abstract The study comprises the effect of different bleaching parameters on scoured single jersey cotton fabrics. Three different concentrations 1.8 gL 2.0 gL and 2.2 gL taken from 5 stock solution of hydrogen peroxide were considered for the experiment. In each concentration bleaching was performed in four individual temperatures 78C 88C 98C and 108C. In each of the temperatures bleaching were continued for four individual time period 20 30 40 and 50 minutes. The weight of sample fabric was 12.5 grams and 110 liquor ratio was maintained in each operation. The bleached samples were tested in a reflectance spectrophotometer datacolor 650 and also their bursting strengths were found from an Autoburst instrument following ISO 13038-1 method. The results show that bursting strength and whiteness index have an inverse relation between themselves. For the nominated concentrations of peroxide 88C to 98C temperature with 30 to 40 minutes time duration is suggested as the optimum bleaching parameter for knitted cotton fabric.

  5. Assessing the effects of hydrogen peroxide bleaching agent on the shear bond strength of orthodontic brackets.

    Science.gov (United States)

    Andrighetto, Augusto Ricardo; de Leão Withers, Eduardo Henrique; Grando, Karlos Giovani; Ambrosio, Aldrieli Regina; Shimizu, Roberto Hideo; Melo, Ana Cláudia

    2016-01-01

    Tooth bleaching is, today, one of the most widespread cosmetic treatments in dental practice,  so it is important to determine whether it can interfere with orthodontic bonding or not. The aim of this study was to assess the in vitro effects of 35% hydrogen peroxide bleaching agent on the shear bond strength of orthodontic brackets. Forty-five upper bicuspids were divided into three groups (n = 15). In the control Group (C), the brackets were bonded without previous bleaching treatment. Group 1 (G1) was treated with 35% hydrogen peroxide bleaching agent 24 h before bracket bonding. Group 2 was also bleached, and the brackets were bonded after 30 days. The shear bond strength of the brackets was measured using an EMIC machine, and the results were analyzed by ANOVA. There were no statistically significant differences between the three groups (P > 0.05), with Group C showing a mean bond strength of 9.72 ± 2.63 MPa, G1 of 8.09 ± 2.63 MPa, and G2 of 11.15 ± 4.42 MPa. It was possible to conclude that 35% hydrogen peroxide bleaching agent does not affect the shear strength of orthodontic brackets bonded 24 h and 30 days after bleaching.

  6. Response of millepora alcicornis (Milleporina: Milleporidae) to two bleaching enventgs at Puerto Morelos reef, Mexican Caribbean

    International Nuclear Information System (INIS)

    Banaszak, A.T.; Ayala Schiaffino, B.N.; Rodriguez Roman, A.; Enriquez, S.; Iglesias Prieto, R.

    2003-01-01

    Two naturally occurring colonies of Millepora alcicornis were monitored during 1997 and 1998, both years in which this species bleached in the Mexican Caribbean. One colony (HL) was naturally exposed to a high light environment and another nearby colony (LL) was exposed to 5.9 times lower light levels due to shadowing by a pier. For 10 days in August 1997, seawater temperatures in the surrounding reef lagoon rose up to 1.5 degrees C above the 6-year August average. The HL colony bleached to white during this period, whereas, the LL colony remained dark-brown colored. The HL colony recovered its normal dark-brown coloration (reversible bleaching) within several weeks, during which time the seawater temperatures returned to average. The following year, for 10 days, seawater temperatures rose up to 3 degrees C above the 7-year August average and both colonies bleached to white and neither colony recovered (irreversible bleaching). Both colonies were rapidly overgrown by algae and hydroids and, as of June 2003, no recovery has taken place. Prior to the 1997 bleaching, experiments using solar radiation showed that the quantum yield of photosystem II charge separation of branches from HL and LL colonies were affected for several hours by exposure to ultraviolet radiation (UVR, 280 to 400 nm), but recovered by the same evening, suggesting that UVR does not have long-term effects on photochemistry in M. alcicornis. In situ effective quantum yield of photosystem II charge separation (ΔF/Fm ' ) measurements before the 1998 bleaching event indicate that both colonies were healthy in terms of the physiological status of their endosymbionts. During and after the 1998 bleaching event, both colonies showed a reduction in ΔF/Fm ' and consequently an increase in excitation pressure on photosystem II. The data suggest that temperature is not the only factor that causes bleaching and that solar radiation may play an important role in coral bleaching. (Author)

  7. A randomized CIE L*a*b* evaluation of external bleaching therapy effects on fluorotic enamel stains.

    Science.gov (United States)

    Knösel, Michael; Attin, Rengin; Becker, Klaus; Attin, Thomas

    2008-05-01

    To evaluate the effect of external bleaching on the color and luminosity of fluorotic stains and adjacent, normally mineralized enamel areas by means of CIE L*a*b* colorimetry. Eighteen adolescents with mild to moderate fluorotic stains were randomly assigned to either bleaching group A (n = 9) or control group B. Eligibility criteria were fluorotic stained maxillary incisors or canines and the informed consent of the participants and their guardians. Using a colorimeter, CIE L*a*b* values of maxillary incisors and canines were assessed at baseline (T1) in the center of the fluorotic stained area (F1) and at adjacent, normally mineralized enamel areas (F2). Then, external bleaching with Illumine office (30% hydrogen peroxide, Dentsply DeTrey) was performed for 60 minutes, followed by color reassessment (T2). After 14 days (T3), a 2-week home bleaching period with a daily bleaching time of 1 hour with Illumine home (15% carbamide peroxide, Dentsply DeTrey) was conducted with subsequent color determination (T4). After completion of bleaching therapy, 96.0% of all fluorotic areas (F1) and 100% of normal enamel areas (F2) showed a significant change within group A, compared to 29.4% in control group B. Comparing the collective DeltaE (L*, a*, b*) of F1 and F2, 60.0% of all areas showed significant differences after completion of bleaching therapy, compared to 88.0% initially. Of group B sites, 82.4% showed color differences in the beginning (T1) and 88.2% at the end (T4). Whereas a single 1-hour session of in-office bleaching with 30% hydrogen peroxide does not significantly affect the color and luminosity of fluorotic teeth, a 14-day period of home bleaching leads to an assimilation of the color of the fluorotic stain with the color of surrounding enamel areas due to different responses of sound and fluorotic enamel to the bleaching regime.

  8. Status of defense radioactive waste disposal activities

    International Nuclear Information System (INIS)

    Wade, T.W.

    1988-01-01

    The Office of Defense Programs, U.S. Department of Energy, is responsible for the production of nuclear weapons and materials for national defense. As a byproduct to their activities, nuclear production facilities have generated, and will continue to generate, certain radioactive, hazardous, or mixed wastes that must be managed and disposed of in a safe and cost-effective manner. Compliance with all applicable Federal and State regulations is required. This paper describes the principal elements that comprise Defense Programs' approach to waste management and disposal. The status of high-level, transuranic, and low-level radioactive waste disposal is set forth. Defense Programs' activities in connection with the environmental restoration of inactive facilities and with the safe transport of waste materials are summarized. Finally, the principal challenges to realizing the goals set for the defense waste program are discussed in terms of regulatory, public acceptance, technical, and budget issues

  9. Trace metal anomalies in bleached Porites coral at Meiji Reef, tropical South China Sea

    Science.gov (United States)

    Li, Shu; Yu, Kefu; Zhao, Jianxin; Feng, Yuexing; Chen, Tianran

    2017-01-01

    Coral bleaching has generally been recognized as the main reason for tropical coral reef degradation, but there are few long-term records of coral bleaching events. In this study, trace metals including chromium (Cr), copper (Cu), molybdenum (Mo), manganese (Mn), lead (Pb), tin (Sn), titanium (Ti), vanadium (V), and yttrium (Y), were analyzed in two Porites corals collected from Meiji Reef in the tropical South China Sea (SCS) to assess differences in trace metal concentrations in bleached compared with unbleached coral growth bands. Ti, V, Cr, and Mo generally showed irregular fluctuations in both corals. Bleached layers contained high concentrations of Mn, Cu, Sn, and Pb. Unbleached layers showed moderately high concentrations of Mn and Cu only. The different distribution of trace metals in Porites may be attributable to different selectivity on the basis of vital utility or toxicity. Ti, V, Cr, and Mo are discriminated against by both coral polyps and zooxanthellae, but Mn, Cu, Sn, and Pb are accumulated by zooxanthellae and only Mn and Cu are accumulated by polyps as essential elements. The marked increase in Cu, Mn, Pb, and Sn are associated with bleaching processes, including mucus secretion, tissue retraction, and zooxanthellae expulsion and occlusion. Variation in these trace elements within the coral skeleton can be used as potential tracers of short-lived bleaching events.

  10. The effect of dental bleaching on pulpal tissue response in a diabetic animal model.

    Science.gov (United States)

    Cintra, L T A; Ferreira, L L; Benetti, F; Gastélum, A A; Gomes-Filho, J E; Ervolino, E; Briso, A L F

    2017-08-01

    To evaluate pulpal tissue response after dental bleaching in normal and alloxan-induced diabetic rats. Twenty-eight rats were divided into two groups of normoglycaemic and diabetic rats (n = 14). Diabetes mellitus (DM) was induced with alloxan. After DM confirmation, all rats were anaesthetized and dental bleaching was performed with 35% hydrogen peroxide (H 2 O 2 ) on the right maxillary molars for 30 min. Left molars were used as controls. Bleaching resulted in four hemimaxillae groups: normoglycaemic (N), N-bleached (NBle), diabetic (D) and D-bleached (DBle). After 2 or 30 days, the animals were euthanized and the hemimaxillae were removed, processed for histopathological analysis and stained with haematoxylin-eosin (HE), Masson's trichrome (MT) and picrosirius red (PSR). Results obtained within animals (normoglycaemic or diabetic rats) were submitted to Wilcoxon or paired t-tests, and between animal (normoglycaemic and diabetic rats), to Mann-Whitney test or t-tests. At 2 days, the NBle group had a mild inflammatory infiltration in the pulpal tissue, whilst the DBle had severe inflammation or necrosis (P bleaching was greater in diabetic rats. Additionally, the increase in reactionary dentine deposition and mature collagen fibres observed in diabetic rats needs further evaluation to confirm the present results. © 2016 International Endodontic Journal. Published by John Wiley & Sons Ltd.

  11. Titanium dioxide in dental enamel as a trace element and its variation with bleaching.

    Science.gov (United States)

    Vargas-Koudriavtsev, Tatiana; Durán-Sedó, Randall; Herrera-Sancho, Óscar-Andrey

    2018-06-01

    Titanium is a less studied trace element in dental enamel. Literature relates an increased Titanium concentration with a decreased enamel crystal domain size, which in turn is related to a higher color value. The aim of our study was to analyze the effect of tooth bleaching agents on its concentration in dental enamel by means of confocal Raman spectroscopy. Human teeth were randomly distributed in six experimental groups (n=10) and submitted to different bleaching protocols according to the manufacturer´s instructions. Confocal Raman spectroscopy was carried out in order to identify and quantify the presence of titanium dioxide molecules in enamel prior to and during whitening. Statistical analysis included repeated measures analysis of variance ( p ≤0.05) and Bonferroni pairwise comparisons. Titanium dioxide concentration was negatively affected by the longer bleaching protocols (at-home bleaching gels). All in-office whitening products increased significantly the studied molecule ( p ≤0,05). All dental specimens depicted the presence of titanium dioxide as a trace element in dental enamel. Bleaching gels that have to be applied at higher concentrations but for shorter periods of time increase the concentration of titanium dioxide, whilst at-home whitening gels used for longer periods of time despite the lower concentration caused a loss in titanium. Key words: Bleaching, whitening, hydrogen peroxide, carbamide peroxide, Raman spectroscopy, titanium dioxide.

  12. Effect of Er,Cr:YSGG laser irradiation on bovine enamel surface during in-office tooth bleaching ex vivo.

    Science.gov (United States)

    Dionysopoulos, Dimitrios; Strakas, Dimitrios; Koliniotou-Koumpia, Eugenia; Koumpia, Effimia

    2017-07-01

    The aim of this in vitro study was to evaluate the effect of using Er,Cr:YSGG laser during in-office tooth bleaching on bovine enamel surface to evaluate the safety of this therapy on tooth tissues. Thirty-six enamel specimens were prepared from bovine incisors and divided into three groups: Group 1 specimens (control) received no bleaching treatment; Group 2 received a conventional in-office bleaching treatment (40 % H 2 O 2 ); Group 3 received laser-assisted bleaching procedure (40 % H 2 O 2 ) utilizing an Er,Cr:YSGG laser. The specimens were stored for 10 days after the bleaching treatment in artificial saliva. Vickers hardness was determined using a microhardness tester, and measurements for surface roughness were done using a VSI microscope. Three specimens for each experimental group were examined under SEM and mineral composition of the specimens was evaluated using EDS. Data were statistically analyzed using one-way ANOVA, Tukey's post hoc, Wilcoxon signed rank and Kruskal-Wallis tests (a = 0.05). The Vickers hardness of the enamel was reduced after in-office bleaching procedures (p  0.05), and no changes in mineral composition of the enamel were detected after in-office bleaching procedures (p > 0.05). The laser-assisted bleaching treatment with Er,Cr:YSGG laser did not influence the enamel surface compared to the conventional bleaching technique. The safety of the use of Er,Cr:YSGG laser during in-office tooth bleaching regarding the surface properties of the enamel was confirmed under in vitro conditions.

  13. Xylanase-Aided Chlorine Dioxide Bleaching of Bagasse Pulp to Reduce AOX Formation

    Directory of Open Access Journals (Sweden)

    Yi Dai

    2016-02-01

    Full Text Available Xylanase pretreatment was used to improve the chlorine dioxide bleaching of bagasse pulp. The pulp was pretreated with xylanase, which was followed by a chlorine dioxide bleaching stage. The HexA content of the pulp and the AOX content of the bleaching effluent were measured using UV-Vis and GC-MS methods, respectively. The results showed that a good correlation occurred between HexA and kappa number. HexA content of the pulp decreased significantly after the xylanase pretreatment. The AOX content of the bleaching effluent decreased as HexA was removed from the pulp. It was found that AOX could be reduced by up to 29.8%, comparing XD0 with a D0 stage. Fourier transform infrared spectroscopy (FTIR was employed to determine the breakage of chemical bonds in the pulp. It revealed that some lignin and hemicellulose were removed after xylanase treatment. The GC-MS results showed that some toxic chloride such as 2,4,6-trichlorophenol could be completely removed after xylanase pretreatment.

  14. Compositional changes of human hair melanin resulting from bleach treatment investigated by nanoscale secondary ion mass spectrometry.

    Science.gov (United States)

    Kojima, Toru; Yamada, Hiromi; Isobe, Mitsuru; Yamamoto, Toshihiko; Takeuchi, Miyuki; Aoki, Dan; Matsushita, Yasuyuki; Fukushima, Kazuhiko

    2014-11-01

    It is important to understand the influence of bleach treatment on human hair because it is one of the most important chemical treatments in hair cosmetic processes. A comparison of the elemental composition of melanin between virgin hair and bleached hair would provide important information about the structural changes of melanin. To investigate the elemental composition of melanin granules in virgin black hair and bleached hair, these hair cross-sections are analyzed by using a nanoscale secondary ion mass spectrometry (NanoSIMS). The virgin black hair and bleached hair samples were embedded in resin and smooth hair cross-sections were obtained using an ultramicrotome. NanoSIMS measurements were performed using a Cs(+) primary ion beam to detect negative secondary ions. More intensive (16) O(-) ions were detected from the melanin granules of bleached hair than from those of virgin black hair in NanoSIMS (16) O(-) ion image. In addition, it was indicated that (16) O(-) ion intensity and (16) O(-) /(12) C(14) N(-) ion intensity ratio of melanin granules in bleached hair were higher than those in virgin black hair. Nanoscale secondary ion mass spectrometry analysis of the cross-sections of virgin black hair and bleached hair indicated that the oxygen content in melanin granules was increased by bleach treatment. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  15. In-office bleaching efficacy on stain removal from CAD/CAM and direct resin composite materials.

    Science.gov (United States)

    Alharbi, Amal; Ardu, Stefano; Bortolotto, Tissiana; Krejci, Ivo

    2018-01-01

    To evaluate the efficacy of in-office bleaching on stain removal from stained resin composite and ceramic computer-assisted design/computer-assisted manufacturing (CAD/CAM) blocks and direct resin composites. Forty disk-shaped samples were fabricated from each of nine materials: six CAD/CAM (VITABLOCS Mark II, Paradigm MZ100, Exp Vita Hybrid Ceramic, VITA ENAMIC, Exp Kerr, and LAVA Ultimate) and three direct resin composites (Filtek Supreme, Venus Diamond, and Filtek Silorane). Samples were randomly divided into five groups (n = 8), each stained with a particular staining solution. Using a calibrated spectrophotometer and a black background, L*a*b* values were assessed before and after 120 days of staining. Samples were subjected to in-office bleaching using 40% hydrogen peroxide gel for one hour. At subsequent assessment, color change (ΔE) was calculated as the difference between L*a*b* values. Both ANOVA and the Duncan test were used to identify differences between groups (α = 0.05). Bleaching resulted in significant differences in ΔE values for all materials (P Bleaching efficacy was highly influenced by material composition and staining solution. Residual color values after bleaching for ceramic and hybrid ceramics ranged from -0.49 to 2.35, within the clinically acceptable maximum of 3.3. Values after bleaching for resin-based CAD/CAM ranged from -0.7 to 7.08 while direct resin composites values ranged from -1.47 to 25.13. Coffee left the greatest residual color on all materials. Based on material nature, 40% hydrogen peroxide bleaching can remove staining. The new resin-based CAD/CAM blocks showed promising results in terms of color stability. Bleaching using 40% hydrogen peroxide can be an effective method to remove stains from dental restorations. In this way, restoration replacement as a result of discoloration may no longer be necessary. © 2017 Wiley Periodicals, Inc.

  16. Transporting Radioactive Waste: An Engineering Activity. Grades 5-12.

    Science.gov (United States)

    HAZWRAP, The Hazardous Waste Remedial Actions Program.

    This brochure contains an engineering activity for upper elementary, middle school, and high school students that examines the transportation of radioactive waste. The activity is designed to inform students about the existence of radioactive waste and its transportation to disposal sites. Students experiment with methods to contain the waste and…

  17. Impact of bleaching agents on water sorption and solubility of resin luting cements.

    Science.gov (United States)

    Torabi Ardakani, Mahshid; Atashkar, Berivan; Bagheri, Rafat; Burrow, Michael F

    2017-08-01

    The aim of the present study was to evaluate the effect of distilled water and home and office bleaching agents on the sorption and solubility of resin luting cements. A total of 18 disc-shaped specimens were prepared from each of four resin cements: G-CEM LinkAce, Panavia F, Rely X Unicem, and seT. Specimens were cured according to the manufacturers' instructions and randomly divided into three groups of six, where they were treated with either an office or home bleaching agent or immersed in distilled water (control). Water sorption and solubility were measured by weighing the specimens before and after immersion and desiccation. Data were analyzed using Pearson correlation coefficient, two-way analysis of variance (ANOVA) and Tukey's test. There was a significant, positive correlation between sorption and solubility. Two-way anova showed significant differences among all resin cements tested for either sorption or solubility. Water sorption and solubility of all cements were affected significantly by office bleaching, and even more by home bleaching agents. Sorption and solubility behavior of the studied cements were highly correlated and significantly affected by applying either office or home bleaching agents; seT showed the highest sorption and solubility, whereas Rely X Unicem revealed the lowest. © 2016 John Wiley & Sons Australia, Ltd.

  18. Technology development activities supporting tank waste remediation

    International Nuclear Information System (INIS)

    Bonner, W.F.; Beeman, G.H.

    1994-06-01

    This document summarizes work being conducted under the U.S. Department of Energy's Office of Technology Development (EM-50) in support of the Tank Waste Remediation System (TWRS) Program. The specific work activities are organized by the following categories: safety, characterization, retrieval, barriers, pretreatment, low-level waste, and high-level waste. In most cases, the activities presented here were identified as supporting tank remediation by EM-50 integrated program or integrated demonstration lead staff and the selections were further refined by contractor staff. Data sheets were prepared from DOE-HQ guidance to the field issued in September 1993. Activities were included if a significant portion of the work described provides technology potentially needed by TWRS; consequently, not all parts of each description necessarily support tank remediation

  19. Skin bleaching: A neglected form of injury and threat to global skin ...

    African Journals Online (AJOL)

    Skin bleaching: A neglected form of injury and threat to global skin. JC Street, K Gaska, KM Lewis, ML Wilson. Abstract. Skin bleaching is the use of creams, gels, or soaps to lighten the skin and is known to cause a number of injuries, many of which are potentially life-threatening. Despite the growing body of research ...

  20. Radioecological activity limits for radioactive waste disposal

    International Nuclear Information System (INIS)

    Ahmet, E. Osmanlioglu

    2006-01-01

    Full text: Near surface disposal is an option used by many countries for the disposal of radioactive waste containing mainly short lived radionuclides. Near surface disposal term includes broad range of facilities from simple trenches to concrete vaults. Principally, disposal of radioactive waste requires the implementation of measures that will provide safety for human health and environment now and in the future. For this reason preliminary activity limits should be determined to avoid radioecological problems. Radioactive waste has to be safely disposed in a regulated manner, consistent with internationally agreed principles and standards and with national legislations to avoid serious radioecological problems. The purpose of this study, presents a safety assessment approach to derive operational and post-closure radioecological activity limits for the disposal of radioactive waste. Disposal system has three components; the waste, the facility (incl. engineered barriers) and the site (natural barriers). Form of the waste (unconditioned or conditioned) is effective at the beginning of the migration scenerio. Existence of the engineered barriers in the facility will provide long term isolation of the waste from environment. The site characteristics (geology, groundwater, seismicity, climate etc.) are important for the safety of the system. Occupational exposure of a worker shall be controlled so that the following dose limits are not exceeded: an effective dose of 20mSv/y averaged over 5 consecutive years; and an effective dose of 50mSv in any single year. The effective dose limit for members of the public recommended by ICRP and IAEA is 1 mSv/y for exposures from all man-made sources [1,2]. Dose constraints are typically a fraction of the dose limit and ICRP recommendations (0.3 mSv/y) could be applied [3,4]. Radioecological activity concentration limits of each radionuclide in the waste (Bq/kg) were calculated. As a result of this study radioecological activity

  1. Coral recovery in the central Maldives archipelago since the last major mass-bleaching, in 1998

    Science.gov (United States)

    Pisapia, C.; Burn, D.; Yoosuf, R.; Najeeb, A.; Anderson, K. D.; Pratchett, M. S.

    2016-10-01

    Increasing frequency and severity of disturbances is causing global degradation of coral reef ecosystems. This study examined temporal changes in live coral cover and coral composition in the central Maldives from 1997 to 2016, encompassing two bleaching events, a tsunami, and an outbreak of Acanthaster planci. We also examined the contemporary size structure for five dominant coral taxa (tabular Acropora, Acropora muricata, Acropora humilis, Pocillopora spp, and massive Porites). Total coral cover increased throughout the study period, with marked increases following the 1998 mass-bleaching. The relative abundance of key genera has changed through time, where Acropora and Pocillopora (which are highly susceptible to bleaching) were under-represented following 1998 mass-bleaching but increased until outbreaks of A. planci in 2015. The contemporary size-structure for all coral taxa was dominated by larger colonies with peaked distributions suggesting that recent disturbances had a disproportionate impact on smaller colonies, or that recruitment is currently limited. This may suggest that coral resilience has been compromised by recent disturbances, and further bleaching (expected in 2016) could lead to highly protracted recovery times. We showed that Maldivian reefs recovered following the 1998 mass-bleaching event, but it took up to a decade, and ongoing disturbances may be eroding reef resilience.

  2. Sugar enrichment provides evidence for a role of nitrogen fixation in coral bleaching

    KAUST Repository

    Pogoreutz, Claudia; Radecker, Nils; Cardenas, Anny; Gä rdes, Astrid; Voolstra, Christian R.; Wild, Christian

    2017-01-01

    The disruption of the coral-algae symbiosis (coral bleaching) due to rising sea surface temperatures has become an unprecedented global threat to coral reefs. Despite decades of research, our ability to manage mass bleaching events remains hampered by an incomplete mechanistic understanding of the processes involved. In this study, we induced a coral bleaching phenotype in the absence of heat and light stress by adding sugars. The sugar addition resulted in coral symbiotic breakdown accompanied by a fourfold increase of coral-associated microbial nitrogen fixation. Concomitantly, increased N:P ratios by the coral host and algal symbionts suggest excess availability of nitrogen and a disruption of the nitrogen limitation within the coral holobiont. As nitrogen fixation is similarly stimulated in ocean warming scenarios, here we propose a refined coral bleaching model integrating the cascading effects of stimulated microbial nitrogen fixation. This model highlights the putative role of nitrogen-fixing microbes in coral holobiont functioning and breakdown.

  3. Sugar enrichment provides evidence for a role of nitrogen fixation in coral bleaching

    KAUST Repository

    Pogoreutz, Claudia

    2017-04-21

    The disruption of the coral-algae symbiosis (coral bleaching) due to rising sea surface temperatures has become an unprecedented global threat to coral reefs. Despite decades of research, our ability to manage mass bleaching events remains hampered by an incomplete mechanistic understanding of the processes involved. In this study, we induced a coral bleaching phenotype in the absence of heat and light stress by adding sugars. The sugar addition resulted in coral symbiotic breakdown accompanied by a fourfold increase of coral-associated microbial nitrogen fixation. Concomitantly, increased N:P ratios by the coral host and algal symbionts suggest excess availability of nitrogen and a disruption of the nitrogen limitation within the coral holobiont. As nitrogen fixation is similarly stimulated in ocean warming scenarios, here we propose a refined coral bleaching model integrating the cascading effects of stimulated microbial nitrogen fixation. This model highlights the putative role of nitrogen-fixing microbes in coral holobiont functioning and breakdown.

  4. Effect of Opalescence® bleaching gels on the elution of dental composite components.

    Science.gov (United States)

    Schuster, Lena; Rothmund, Lena; He, Xiuli; Van Landuyt, Kirsten L; Schweikl, Helmut; Hellwig, Elmar; Carell, Thomas; Hickel, Reinhard; Reichl, Franz-Xaver; Högg, Christof

    2015-06-01

    Bleaching treatments can affect on the polymer network of dental composites. This study was performed to evaluate the influence of different bleaching treatments on the elution of composite components. The composites Tetric EvoCeram(®), CLEARFIL™ AP-X, Tetric EvoFlow(®), Filtek™ Supreme XT, Ceram X(®) mono+, Admira and Filtek™ Silorane were treated with the bleaching gels Opalescence PF 15% (PF 15%) for 5h and PF 35% (PF 35%) for 30 min and then stored in methanol and water for 24h and 7 d. The eluates were analyzed by gas chromatography/mass spectrometry (GC/MS). Unbleached specimens were used as control group. A total of 16 different elutable substances have been identified from the investigated composites after bleaching-treatment. Six of them were methacrylates: 1,10-decandioldimethacrylate (DDDMA), 1,12-dodekandioldimethacrylate (DODDMA), ethylenglycoldimethacrylate (EGDMA), 2-hydroxyethylmethacrylate (HEMA), triethylenglycoldimethacrylate (TEGDMA) and urethandimethacrylate (UDMA). Compared with the unbleached controls the composites Tetric EvoCeram(®), CLEARFIL™ AP-X and Tetric EvoFlow(®) showed a reduced elution of UDMA, TEGDMA and HEMA after bleaching-treatment. Compared with the unbleached controls an increase elution of UDMA, DMABEE, BPA and TEGDMA for the composites Filtek™ Supreme XT, Ceram X(®) mono+, Admira and Filtek™ Silorane after bleaching-treatment has been detected. The highest concentration of UDMA was 0.01 mmol/l (Tetric EvoCeram(®), water, 24h, controls), the highest concentration of TEGDMA was 0.28 mmol/l (CLEARFIL™ AP-X, water, 7 d, controls), the highest concentration of HEMA was 0.74 mmol/l (Tetric EvoFlow(®), methanol, 7 d, PF 35%), the highest concentration of DMABEE was 0.10 mmol/l (Ceram X(®) mono+, water, 7 d, PF 35%) and the highest concentration of BPA was 0.01 mmol/l (Admira, methanol, 7 d, controls). Bleaching treatments can lead to a reduced or an increased elution of substances from the dental composites

  5. A review of the effect of vital teeth bleaching on the mechanical properties of tooth enamel.

    Science.gov (United States)

    Elfallah, Hunida M; Swain, Michael V

    2013-09-01

    Tooth whitening is considered the easiest and most cost-effective procedure for treating tooth discoloration. Contemporary bleaching agents contain hydrogen peroxide as the active ingredient. It is either applied directly or produced from its precursor, carbamide peroxide. A review of the published literature was undertaken to investigate the potential adverse effects of whitening products on dental enamel, with a focus on its mechanical properties and the influence of various parameters on study outcomes. There appear to be considerable differences in opinion as to whether changes in mechanical properties occur as a result of tooth whitening. However, the mechanical property findings of those studies appear to be related to the load applied during the indentation tests. Most studies which used loads higher than 500mN to determine enamel hardness showed no effect of bleaching, whereas those using lower loads were able to detect hardness reduction in the surface layer of enamel. In conclusion, bleaching reduces the hardness of the enamel surface of enamel, and that is more readily detected with instrumented low load testing systems. This hardness reduction may arise due to degradation or denaturation of enamel matrix proteins by the peroxide oxidation.

  6. Acid demineralization susceptibility of dental enamel submitted to different bleaching techniques and fluoridation regimens.

    Science.gov (United States)

    Salomão, Dlf; Santos, Dm; Nogueira, Rd; Palma-Dibb, Rg; Geraldo-Martins, Vr

    2014-01-01

    The aim of the current study was to assess the acid demineralization susceptibility of bleached dental enamel submitted to different fluoride regimens. One hundred bovine enamel blocks (6×6×3 mm) were randomly divided into 10 groups (n=10). Groups 1 and 2 received no bleaching. Groups 3 to 6 were submitted to an at-home bleaching technique using 6% hydrogen peroxide (HP; G3 and G4) or 10% carbamide peroxide (CP; G5 and G6). Groups 7 to 10 were submitted to an in-office bleaching technique using 35% HP (G7 and G8) or 35% CP (G9 and G10). During bleaching, a daily fluoridation regimen of 0.05% sodium fluoride (NaF) solution was performed on groups 3, 5, 7, and 9, while weekly fluoridation with a 2% NaF gel was performed on groups 4, 6, 8, and 10. The samples in groups 2 to 10 were pH cycled for 14 consecutive days. The samples from all groups were then assessed by cross-sectional Knoop microhardness at different depths from the outer enamel surface. The average Knoop hardness numbers (KHNs) were compared using one-way analysis of variance and Tukey tests (α=0.05). The comparison between groups 1 and 2 showed that the demineralization method was effective. The comparison among groups 2 to 6 showed the same susceptibility to acid demineralization, regardless of the fluoridation method used. However, the samples from groups 8 and 10 showed more susceptibility to acid demineralization when compared with group 2 (penamel to acid demineralization. However, the use of 35% HP and 35% CP must be associated with a daily fluoridation regimen, otherwise the in-office bleaching makes the bleached enamel more susceptible to acid demineralization.

  7. Low and medium activity solid wastes processing and encapsulation

    International Nuclear Information System (INIS)

    Taillard, D.; Claes, J.; Hennart, D.

    1983-01-01

    This work, carried out under contract with the European Atomic Energy Community, describes the techniques in use for waste management. The activity of low and medium activity solid wastes is from few curies to few tens of curies per cubic meter, they are produced by nuclear facilities and are often complex mixtures. Radioactive wastes are characterized and processing and conditioning are described. Leaching, stability, mechanical resistance and radiolysis of encapsulated wastes are examined. Handling, storage and disposal are treated

  8. Effect of Home Bleaching on Microleakage of Fiber-reinforced and Particle-filled Composite Resins

    Directory of Open Access Journals (Sweden)

    Farahnaz Sharafeddin

    2013-12-01

    Full Text Available Background and aims. Bleaching may exert some negative effects on existing composite resin restorations. The aim of this study was to evaluate the effect of home bleaching on microleakage of fiber-reinforced and particle-filled composite resins. Materials and methods. Ninety class V cavities (1.5×2×3 mm were prepared on the buccal surfaces of 90 bovine teeth. The teeth were randomly divided into 6 groups (n=15 and restored as follows: Groups 1 and 2 with Z100, groups 3 and 4 with Z250, and groups 5 and 6 with Nulite F composite resins. All the specimens were thermocycled. Groups 1, 3 and 5 were selected as control groups (without bleaching and the experimental groups 2, 4 and 6 were bleached with 22% carbamide peroxide gel. All the samples were immersed in 2% basic fuchsin dye for 24 hours and then sectioned longitudinally. Dye penetration was evaluated under a stereomicroscope (×25, at both the gingival and incisal margins. Data were analyzed using Kruskal-Wallis, Mann-Whitney and Wilcoxon tests (α=0.05. Results. Statistical analyses revealed that bleaching gel increased microleakage only at gingival margins with Z250 (P=0.007. Moreover, the control groups showed a statistically significant difference in microleakage at their gingival margins. Nulite F had the maximum microleakage while Z250 showed the minimum (P=0.006. Conclusion. Microleakage of home-bleached restorations might be related to the type of composite resin used.

  9. Aube very low activity waste storage Centre. Annual report 2009

    International Nuclear Information System (INIS)

    2010-01-01

    After a presentation of the ANDRA (the French national agency for radioactive waste management), its role and missions, its sites, its strategy with respect to a sustainable development, this report contains a description of waste storage installations and key figures of the activity in 2009 (origin and nature of very low activity wastes, brief description of the Aube centre installations, stored volumes, performed works). It describes arrangements related to security, safety and radioprotection, presents results of the radiological survey activity performed in the environment and on wastes, and activities related to public information

  10. Quarterly Briefing Book on Environmental and Waste Management Activities

    Energy Technology Data Exchange (ETDEWEB)

    Brown, M.C.

    1991-06-01

    The purpose of the Quarterly Briefing Book on Environmental and Waste Management Activities is to provide managers and senior staff at the US Department of Energy-Richland Operations Office and its contractors with timely and concise information on Hanford Site environmental and waste management activities. Each edition updates the information on the topics in the previous edition, deletes those determined not to be of current interest, and adds new topics to keep up to date with changing environmental and waste management requirements and issues. Section A covers current waste management and environmental restoration issues. In Section B are writeups on national or site-wide environmental and waste management topics. Section C has writeups on program- and waste-specific environmental and waste management topics. Section D provides information on waste sites and inventories on the site. 15 figs., 4 tabs.

  11. Quarterly Briefing Book on Environmental and Waste Management Activities

    International Nuclear Information System (INIS)

    Brown, M.C.

    1991-06-01

    The purpose of the Quarterly Briefing Book on Environmental and Waste Management Activities is to provide managers and senior staff at the US Department of Energy-Richland Operations Office and its contractors with timely and concise information on Hanford Site environmental and waste management activities. Each edition updates the information on the topics in the previous edition, deletes those determined not to be of current interest, and adds new topics to keep up to date with changing environmental and waste management requirements and issues. Section A covers current waste management and environmental restoration issues. In Section B are writeups on national or site-wide environmental and waste management topics. Section C has writeups on program- and waste-specific environmental and waste management topics. Section D provides information on waste sites and inventories on the site. 15 figs., 4 tabs

  12. Activity monitoring of alpha-bearing wastes

    International Nuclear Information System (INIS)

    Birkhoff, G.; Bondar, L.

    1980-01-01

    The paper aims at the survey on the actual situation in activity monitoring of alpha-bearing wastes. Homogeneous materials such as liquid-, gaseous- and homogeneous solid wastes are amenable to destructive analyses of representative samples. Available destructive analyses methods are sensitive and precise enough to cope with all requirements in alpha-waste monitoring. The more difficult problems are encountered with alpha-contaminated solids, when representative sampling is not practicable. Non-destructive analysis techniques are applied for monitoring this category of solid wastes. The techniques for nondestructive analysis of alpha-bearing wastes are based on the detection of gamma and/or neutron-emission of actinides. Principles and a theory of non-destructive radiometric assay of plutonium contaminated solid waste streams are explained. Guidelines for the calibration of instruments and interpretation of experimental data are given. Current theoretical and experimental development work in this problem area is reviewed. Evaluations concerning capabilities and limitations of monitoring systems for alpha-bearing solid wastes are very complex and out of the scope of this paper

  13. Bleach Solution Requirement for Hatching of Daphnia magna Resting Eggs

    Directory of Open Access Journals (Sweden)

    Catur Retnaningdyah

    2016-11-01

    Full Text Available Daphnia (water fleas belong to the zooplankton group called Cladocerans have sexual reproduction when conditions less favorable that produce diapausing eggs are enclosed in the ephippium. Hatching ephippial eggs in the laboratory is important in ecological, toxicology, genetical, and evolutionary studies. This study aims to improve the current methods of egg hatching from ephippium. Each of 50 ephippium were treated together by placing them in a glass jar and adding 50 mL bleach solution (sodium hypochlorite. Concentrations of sodium hypochlorite used in this experiment were 0%, 0.5%, 1%, 2%, 4% and 8%. These concentration treatments were crossed with the following exposure times (1, 2, 4, 8, 16, and 32 minutes. Culturing was done in 80 mL of artificial Daphnia medium, incubated in constant light and temperatures 20°C for 25 days. There were two repetitions in this experiment that were run at the same time. Result of this experiment showed that pretreatment with 0.5-8% bleach solution significantly increases the yield of total hatch rate of Daphnia magna resting eggs by about 21% over unbleached control. However, there was no significant difference among the bleach treatments. Concentration of bleach solution 0.5%, 1% and 4% significantly accelerated the time period until the first hatching (first day hatching. Difference of exposure time (1 - 32 minutes at each concentration treatments were not influence the yield of total hatch and the time period until first hatching.

  14. Activities of the IAEA in the area of radioactive waste management

    International Nuclear Information System (INIS)

    Efremenkov, V.M.

    1998-01-01

    The IAEA activity in the area of radioactive waste management mainly concentrates on three areas, namely: (i) the establishing of international principles and standards for the safe management of radioactive waste; (ii) to promote the development and improvements of waste processing technologies, including handling, treatment, conditioning, packaging, storage and disposal of waste; and (iii) assisting developing Member States in establishing good waste management practice through dissemination of technical information, providing technical support and training. These activities are carried out by the Waste Technology Section, Department of Nuclear Energy, and the Waste Safety Section, Department of Nuclear Safety. The Waste Technology Section's activities are organized into four subprogrammes covering: the handling, processing and storage of radioactive waste; radioactive waste disposal; technology and management aspects of decontamination, decommissioning and environmental restoration; and waste management information and support services

  15. Comparing Environmental Influences on Coral Bleaching Across and within Species using Clustered Binomial Regression

    Science.gov (United States)

    Differential susceptibility among reef-building coral species can lead to community shifts and loss of diversity as a result of temperature-induced mass bleaching events. However, the influence of the local environment on species-specific bleaching susceptibilities has not been ...

  16. Re-evaluating luminescence burial doses and bleaching of fluvial deposits using Bayesian computational statistics.

    NARCIS (Netherlands)

    Cunningham, A.C.; Wallinga, J.; Versendaal, Alice; Makaske, A.; Middelkoop, H.; Hobo, N.

    2015-01-01

    The optically stimulated luminescence (OSL) signal from fluvial sediment often contains a remnant from the previous deposition cycle, leading to a partially bleached equivalent-dose distribution. Although identification of the burial dose is of primary concern, the degree of bleaching could

  17. Re-evaluating luminescence burial doses and bleaching of fluvial deposits using Bayesian computational statistics

    NARCIS (Netherlands)

    Cunningham, A. C.; Wallinga, J.; Hobo, N.; Versendaal, A. J.; Makaske, B.; Middelkoop, H.

    2015-01-01

    The optically stimulated luminescence (OSL) signal from fluvial sediment often contains a remnant from the previous deposition cycle, leading to a partially bleached equivalent-dose distribution. Although identification of the burial dose is of primary concern, the degree of bleaching could

  18. Hydrogen peroxide bleaching induces changes in the physical properties of dental restorative materials: Effects of study protocols.

    Science.gov (United States)

    Yu, Hao; Zhang, Chang-Yuan; Wang, Yi-Ning; Cheng, Hui

    2018-03-01

    The purpose of this study was to evaluate the influence of study protocols on the effects of bleaching on the surface roughness, substance loss, flexural strength (FS), flexural modulus (FM), Weibull parameters, and color of 7 restorative materials. The test materials included 4 composite resins, 1 glass-ionomer cement, 1 dental ceramic, and 1 polyacid-modified composite. The specimens were randomly divided into 4 groups (n = 20) according to different study protocols: a bleaching group at 25°C (group 25B), a bleaching group at 37°C (group 37B), a control group at 25°C (group 25C), and a control group at 37°C (group 37C). The specimens in the bleaching group were treated with 40% hydrogen peroxide for 80 min at the respective environmental temperatures. The surface roughness, substance loss, FS, FM, and color of the specimens were measured before and after treatment. FS data were also subjected to Weibull analysis, which was used to estimate of the Weibull modulus (m) and the characteristic strength (σ 0 ). Surface roughness increased and significant color changes were observed for all tested specimens after bleaching treatment, except for the ceramic. After bleaching at 37°C, the polyacid-modified composite showed significantly reduced FS, FM, m, and σ 0 values in comparison to the control specimens stored at 37°C in whole saliva. Significant differences were also found between the 37B and 25B polyacid-modified composite groups in terms of surface roughness, FS, m, σ 0 , and color changes. Varying effects of bleaching on the physical properties of dental restorative materials were observed, and the influences of the study protocols on bleaching effects were found to be material-dependent. The influence of study protocols on the effects of bleaching on the surface roughness, flexural properties, and color of dental restorative materials are material-dependent and should be considered when evaluating the effects of bleaching on dental restorative

  19. Thermographic and spectrophotometric analysis of the extrinsic tooth bleaching using a diode laser and a LED system. In vitro; Analise termografica e espectrofotometrica do clareamento dental extrinsico utilizando laser de diodo e sistema de LED. Estudio In vitro

    Energy Technology Data Exchange (ETDEWEB)

    Micheli, Paola Racy de

    2004-07-01

    The aim of this study was to evaluate the intra-pulpal temperature change, as well as to compare the bleaching power of a 38% hydrogen peroxide (Opalescence Xtra Boost- Ultradent. Inc), when activated with a diode laser, with a LED system and without activation, in the extrinsic tooth bleaching in vitro. Ten mandibular human incisors, a thermocouple, 45 bovine incisors and a spectrophotometer (Shade Eye- Shofu) for the color analysis. The samples were divided into 3 groups: 38% hydrogen peroxide activated by a diode laser (ZAP lasers, wavelength 808 nm {+-} 5, power of 1,4 W); 38% hydrogen peroxide activated by LED (Bright LEC-Mmoptics, wavelength 470 nm {+-} 25, power of 380 mW); 38% hydrogen peroxide without activation. After the artificial pigmentation, the bleaching agent acted for the same time in the 3 groups, differing only by the type of activation. The results of temperature showed that the LED activation was safer than the diode laser, which, in some measures exceeded the limit of 5.6 deg C. The luminosity of the samples did not show significantly statistics differences in none of the groups and moments of this study. The diode laser and LED activation did not influenced at the bleaching power of the peroxide, which showed effective for removing stains, with great capacity of bleaching bovine tooth artificially darkened. (author)

  20. Relative Contributions of Various Cellular Mechanisms to Loss of Algae during Cnidarian Bleaching.

    Science.gov (United States)

    Bieri, Tamaki; Onishi, Masayuki; Xiang, Tingting; Grossman, Arthur R; Pringle, John R

    2016-01-01

    When exposed to stress such as high seawater temperature, corals and other cnidarians can bleach due to loss of symbiotic algae from the host tissue and/or loss of pigments from the algae. Although the environmental conditions that trigger bleaching are reasonably well known, its cellular and molecular mechanisms are not well understood. Previous studies have reported the occurrence of at least four different cellular mechanisms for the loss of symbiotic algae from the host tissue: in situ degradation of algae, exocytic release of algae from the host, detachment of host cells containing algae, and death of host cells containing algae. The relative contributions of these several mechanisms to bleaching remain unclear, and it is also not known whether these relative contributions change in animals subjected to different types and/or durations of stresses. In this study, we used a clonal population of the small sea anemone Aiptasia, exposed individuals to various precisely controlled stress conditions, and quantitatively assessed the several possible bleaching mechanisms in parallel. Under all stress conditions tested, except for acute cold shock at 4°C, expulsion of intact algae from the host cells appeared to be by far the predominant mechanism of bleaching. During acute cold shock, in situ degradation of algae and host-cell detachment also became quantitatively significant, and the algae released under these conditions appeared to be severely damaged.

  1. Relative Contributions of Various Cellular Mechanisms to Loss of Algae during Cnidarian Bleaching

    Science.gov (United States)

    Bieri, Tamaki; Onishi, Masayuki; Xiang, Tingting; Grossman, Arthur R.; Pringle, John R

    2016-01-01

    When exposed to stress such as high seawater temperature, corals and other cnidarians can bleach due to loss of symbiotic algae from the host tissue and/or loss of pigments from the algae. Although the environmental conditions that trigger bleaching are reasonably well known, its cellular and molecular mechanisms are not well understood. Previous studies have reported the occurrence of at least four different cellular mechanisms for the loss of symbiotic algae from the host tissue: in situ degradation of algae, exocytic release of algae from the host, detachment of host cells containing algae, and death of host cells containing algae. The relative contributions of these several mechanisms to bleaching remain unclear, and it is also not known whether these relative contributions change in animals subjected to different types and/or durations of stresses. In this study, we used a clonal population of the small sea anemone Aiptasia, exposed individuals to various precisely controlled stress conditions, and quantitatively assessed the several possible bleaching mechanisms in parallel. Under all stress conditions tested, except for acute cold shock at 4°C, expulsion of intact algae from the host cells appeared to be by far the predominant mechanism of bleaching. During acute cold shock, in situ degradation of algae and host-cell detachment also became quantitatively significant, and the algae released under these conditions appeared to be severely damaged. PMID:27119147

  2. A Crucial Time for Reefs: Climate Change, El Niño, and the 2014-16 Global Bleaching Event

    Science.gov (United States)

    Eakin, C. M.; Liu, G.; Geiger, E.; Heron, S. F.; Skirving, W. J.; De La Cour, J. L.; Strong, A. E.; Tirak, K.; Burgess, T.

    2016-02-01

    Anthropogenic climate change has caused an increase in the frequency and intensity of coral bleaching, mortality, and other impacts detrimental to the health and survival of coral reefs around the world. In 2014, a global-scale bleaching event, anticipated to last two years or more, began in the Pacific Ocean. Severe bleaching was documented in Guam, the Commonwealth of the Northern Mariana Islands, Hawaii, and the Marshall Islands, among other locations. By mid-2015, severe bleaching had reached many south Pacific Islands and islands of the central to eastern equatorial Pacific, especially Kiribati and Howland and Baker Islands. Bleaching followed in the Indian Ocean, and at the time of this writing is again striking Hawaii, and parts of the Caribbean. As the ongoing El Niño continues to strengthen, long-term outlooks suggest the cycle of bleaching will continue into 2016 in at least the Pacific and Indian Oceans. Caribbean bleaching may follow again in 2016 if this event follows historical patterns. Warming of the global ocean, the El Niño, a new Pacific oceanic feature known as "The Blob", and other patterns are imposing thermal stress capable of causing widespread negative impacts on reefs in many countries and archipelagos. If a subsequent La Niña follows, as is often the case, even more reefs will be subjected to stressful high temperatures. This is resulting in widespread bleaching, disease, and mortality at a frequency and intensity predicted in climate models nearly two decades ago. The question now is if we are seeing the onset of annually returning coral bleaching or if this is just a hint of conditions coming in future decades. This presentation will discuss the latest information on the ongoing third global bleaching event and the impacts it may have on the biology, ecology, and potential for conservation and restoration of corals and coral reefs worldwide.

  3. Effect of ultrasonic pre-treatment of thermomechanical pulp on hydrogen peroxide bleaching

    Science.gov (United States)

    Loranger, E.; Charles, A.; Daneault, C.

    2012-12-01

    Ultrasound pre-treatments of softwood TMP had been carried to evaluate its impact on the efficiency of hydrogen peroxide bleaching. The trials were performed after a factorial design of experiment using frequency, power and time as variables. The experiments were conducted in an ultrasonic bath and then bleached with hydrogen peroxide. Measurements such as brightness, L*A*B* color system coordinate, residual hydrogen peroxide and metal content were evaluated on bleached pulp. The results indicate that the effect of ultrasonic treatment on brightness was dependent on the ultrasound frequency used; the brightness increased slightly at 68 kHz and decreased at 40 and 170 kHz. These results were correlated to the ultrasound effect on the generation of transition metals (copper, iron and manganese) which are responsible for catalytic decomposition of hydrogen peroxide. The influence of metal interference was minimized by using a chelating agent such as diethylene triamine pentaacetic acid (DTPA). With the results obtained in this study we have identified a set of option conditions, e.g. 1000 W, 40 kHz, 1.5 % consistency and 0.2% addition of DTPA prior to the bleaching stage (after ultrasonic pre-treatment) who improve brightness by 2.5 %ISO.

  4. Effect of bleaching on color change and surface topography of composite restorations.

    Science.gov (United States)

    Pruthi, Gunjan; Jain, Veena; Kandpal, H C; Mathur, Vijay Prakash; Shah, Naseem

    2010-01-01

    This study was conducted to determine the effect of 15% carbamide peroxide bleaching agent on color change and surface topography of different composite veneering materials (Filtek Z350 (3M ESPE), Esthet X (Dentsply India), and Admira (Voco, Germany). Methods. 30 samples were fabricated for evaluation of color change using CIELAB color system and Gonioreflectometer (GK 311/M, ZEISS). 45 disc-shaped specimens were made for evaluation of surface topography after bleaching (Nupro White Gold; Dentsply) using SEM. Statistical analysis. One way ANOVA and Multiple comparison tests were used to analyze the data. Statistical significance was declared if the P value was .05 or less. Results and conclusion. All the specimens showed significant discoloration (ΔE > 3.3) after their immersion in solutions representing food and beverages. The total color change after bleaching as compared to baseline color was significant in Filtek Z350 (P = .000) and Esthet X (P = .002), while it was insignificant for Admira (P = .18). Esthet X showed maximum surface roughness followed by Admira and Filtek Z350. Bleaching was effective in reducing the discoloration to a clinically acceptable value in all the three groups (ΔE < 3.3).

  5. Effect of Bleaching on Color Change and Surface Topography of Composite Restorations

    Directory of Open Access Journals (Sweden)

    Gunjan Pruthi

    2010-01-01

    Full Text Available This study was conducted to determine the effect of 15% carbamide peroxide bleaching agent on color change and surface topography of different composite veneering materials (Filtek Z350 (3M ESPE, Esthet X (Dentsply India, and Admira (Voco, Germany. Methods. 30 samples were fabricated for evaluation of color change using CIELAB color system and Gonioreflectometer (GK 311/M, ZEISS. 45 disc-shaped specimens were made for evaluation of surface topography after bleaching (Nupro White Gold; Dentsply using SEM. Statistical analysis. One way ANOVA and Multiple comparison tests were used to analyze the data. Statistical significance was declared if the P value was .05 or less. Results and conclusion. All the specimens showed significant discoloration (ΔE>3.3 after their immersion in solutions representing food and beverages. The total color change after bleaching as compared to baseline color was significant in Filtek Z350 (P=.000 and Esthet X (P=.002, while it was insignificant for Admira (P=.18. Esthet X showed maximum surface roughness followed by Admira and Filtek Z350. Bleaching was effective in reducing the discoloration to a clinically acceptable value in all the three groups (ΔE<3.3.

  6. Biodiesel Production from Residual Palm Oil Contained in Spent Bleaching Earth by In Situ Trans-Esterification

    Directory of Open Access Journals (Sweden)

    A S Fahmil QRM

    2014-06-01

    Full Text Available Spent Bleaching Earth (SBE is an industrial solid waste of vegetable oil industry that has a high residual oil to be potentialy converted to biodiesel. This study aims at developing a biodiesel production process technology by utilizing residual palm oil contained in SBE and to test the use of hexane in the trans-esterification process. Optimization process was done by using the Response Surface Method (RSM. The variables studied included catalyst concentration and reaction time. On the other hand, the deoiled SBE resulted from biodiesel production was tested as an adsorbent on biodiesel purification after being reactivated. The method used in the biodiesel production included an in situ acid catalysed esterification followed by in situ base catalysed trans-esterification. The results of RSM showed that the optimum process was obtained at NaOH concentration of 1.8% and reaction time of 104.73 minutes, with a predicted response rate of 97.18% and 95.63% for validation results. The use of hexane could also increase the yield of biodiesel which was obtained on the ratio of hexane to methanol of 0.4:1 (volume of hexane: volume of methanol. On the other hand, the reactivated bleaching earth was effective as an adsorbent in biodiesel production, which was still conform with the Indonesian National Standard.

  7. Improved microscopical detection of acid-fast bacilli by the modified bleach method in lymphnode aspirates

    Directory of Open Access Journals (Sweden)

    Annam Vamseedhar

    2009-07-01

    Full Text Available Objectives: To improve the smear microscopy for detection of acid-fast bacilli (AFB in fine needle aspiration cytology (FNAC of lymph node using the bleach method and also to compare this with cytological diagnosis and the conventional Ziehl-Neelsen (ZN method. Study Design: In 99 consecutive patients with clinical suspicion of tuberculosis (TB presenting with lymphadenopathy, FNACs were performed. Smears from the aspirates were processed for routine cytology and the conventional ZN method. The remaining material in the needle hub and/or the syringe was used for the bleach method. The significance of the bleach method over the conventional ZN method and cytology was analyzed using the χ2 test. Results: Of 99 aspirates, 93 were studied and the remaining six were excluded from the study due to diagnosis of malignancy in 4.04% (4/6 and inadequate aspiration in 2.02% (2/6. Among the 93 aspirates, 33.33% (31/93 were positive for AFB on conventional ZN method, 41.94% (39/93 were indicative of TB on cytology and the smear positivity increased to 63.44% (59/93 on bleach method. Conclusion: The bleach method is simple, inexpensive and potent disinfectant, also limiting the risk of laboratory-acquired infections. The implementation of the bleach method clearly improves microscopic detection and can be a useful contribution to routine cytology.

  8. Effect of a 16% Carbamide Peroxide Bleaching Gel on Enamel Staining Susceptibility

    Directory of Open Access Journals (Sweden)

    M. Ghavamnasiri

    2005-03-01

    Full Text Available Statement of Problem: Due to the growing popularity of vital bleaching by CarbamidePeroxide it is imperative to understand the effect of such agents on enamel and dentine.Purpose: The purpose of this study was to evaluate the effect of a 16% carbamide peroxide bleaching gel; Vivastyle on enamel staining susceptibility.Materials and Methods: Thirty bovine specimens were selected and randomly divided into two groups of fifteen. The experimental group was subjected to Vivastyle gel and then was immersed in coffee, for half an hour daily for three weeks. The control group was only immersed in coffee. The teeth were evaluated by colorimeter readings to measure L*, a*, b* of each tooth. Total color differences between two colors (ΔE were calculated using the following formula: ΔE= [(ΔL* 2 + (Δa* 2+ (Δb* 2].ΔE1 represent color difference after bleaching; ΔE2: bleached and immersed in coffee,and ΔE3 immersed in coffee.Results: Mean color difference were: 9.478, 13.808, and 7.230 for ΔE1, ΔE2, and ΔE3 respectively. Paired comparison by Duncan test showed that there was a significant difference between ΔE1 and ΔE2 (P0.000. t-test showed that there was no significant difference between ΔE3 and ΔE1. (P=0.08, however, ΔE3 had significant difference with ΔE2 (P0.000.Conclusion: After vital bleaching, the enamel staining susceptibility is significantly increased.

  9. Preemptive use of etodolac on tooth sensitivity after in-office bleaching: a randomized clinical trial.

    Science.gov (United States)

    Vaez, Savil Costa; Faria-E-Silva, André Luís; Loguércio, Alessandro Dourado; Fernandes, Micaelle Tenório Guedes; Nahsan, Flávia Pardo Salata

    2018-02-01

    This study determined the effectiveness of the preemptive administration of etodolac on risk and intensity of tooth sensitivity and the bleaching effect caused by in-office bleaching using 35% hydrogen peroxide. Fifty patients were selected for this tripleblind, randomized, crossover, and placebo-controlled clinical trial. Etodolac (400 mg) or placebo was administrated in a single-dose 1 hour prior to the bleaching procedure. The whitening treatment with 35% hydrogen peroxide was carried out in two sessions with a 7-day interval. Tooth sensitivity was assessed before, during, and 24 hours after the procedure using the analog visual scale and the verbal rating scale. Color alteration was assessed by a bleach guide scale, 7 days after each session. Relative risk of sensitivity was calculated and adjusted by session, while overall risk was compared by the McNemar's test. Data on the sensitivity level of both scales and color shade were subjected to Friedman, Wilcoxon, and Mann-Whitney tests, respectively (α=0.05). The preemptive administration of etodolac did not affect the risk of tooth sensitivity and the level of sensitivity reported, regardless of the time of evaluation and scale used. The sequence of treatment allocation did not affect bleaching effectiveness, while the second session resulted in additional color modification. The preemptive administration of etodolac in a single dose 1 hour prior to in-office tooth bleaching did not alter tooth color, and the risk and intensity of tooth sensitivity reported by patients. A single-dose preemptive administration of 400 mg of etodolac did not affect either risk of tooth sensitivity or level of sensitivity reported by patients, during or after the in-office tooth bleaching procedure.

  10. Photoconductivity and bleaching of trapped electrons at 770C in irradiated methylcyclohexane

    International Nuclear Information System (INIS)

    Dolivo, G.; Gaeumann, T.

    1977-01-01

    The influence of the wavelength and intensity of the bleaching radiation on the thermoluminescence, thermoconductivity, optical absorption and photoconductivity of the methylcyclohexane, protonated and deuterated, was studied. The energy level scheme of the trapped electron in this alkane is very similar to that found in MTHF and 3-MP. The rate of bleaching of the trapped electrons is less in the deuterated product. (U.K.)

  11. LED and low level laser therapy association in tooth bleaching using a novel low concentration H2O2/N-doped TiO2 bleaching agent

    Science.gov (United States)

    Bezerra Dias, Hércules; Teixeira Carrera, Emanuelle; Freitas Bortolatto, Janaína; Ferrarezi de Andrade, Marcelo; Nara de Souza Rastelli, Alessandra

    2016-01-01

    Since low concentration bleaching agents containing N-doped TiO2 nanoparticles have been introduced as an alternative to conventional agents, it is important to verify their efficacy and the hypersensitivity effect in clinical practice. Six volunteer patients were evaluated for color change and hypersensitivity after bleaching using 35% H2O2 (one session of two 12 min applications) and 6% H2O2/N-doped TiO2 (one session of three 12 min applications) and after low level laser therapy application (LLLT) (780 nm, 40 mW, 10 J.cm-2, 10 s). Based on this case study, the nanobleaching agent provided better or similar aesthetic results than the conventional agent under high concentration, and its association with LLLT satisfactorily decreased the hypersensitivity. The 6% H2O2/N-doped TiO2 agent could be used instead of conventional in-office bleaching agents under high concentrations to fulfill the rising patient demand for aesthetics.

  12. In vivo Microscale Measurements of Light and Photosynthesis during Coral Bleaching: Evidence for the Optical Feedback Loop?

    Science.gov (United States)

    Wangpraseurt, Daniel; Holm, Jacob B; Larkum, Anthony W D; Pernice, Mathieu; Ralph, Peter J; Suggett, David J; Kühl, Michael

    2017-01-01

    Climate change-related coral bleaching, i.e., the visible loss of zooxanthellae from the coral host, is increasing in frequency and extent and presents a major threat to coral reefs globally. Coral bleaching has been proposed to involve accelerating light stress of their microalgal endosymbionts via a positive feedback loop of photodamage, symbiont expulsion and excess in vivo light exposure. To test this hypothesis, we used light and O 2 microsensors to characterize in vivo light exposure and photosynthesis of Symbiodinium during a thermal stress experiment. We created tissue areas with different densities of Symbiodinium cells in order to understand the optical properties and light microenvironment of corals during bleaching. Our results showed that in bleached Pocillopora damicornis corals, Symbiodinium light exposure was up to fivefold enhanced relative to healthy corals, and the relationship between symbiont loss and light enhancement was well-described by a power-law function. Cell-specific rates of Symbiodinium gross photosynthesis and light respiration were enhanced in bleached P. damicornis compared to healthy corals, while areal rates of net photosynthesis decreased. Symbiodinium light exposure in Favites sp. revealed the presence of low light microniches in bleached coral tissues, suggesting that light scattering in thick coral tissues can enable photoprotection of cryptic symbionts. Our study provides evidence for the acceleration of in vivo light exposure during coral bleaching but this optical feedback mechanism differs between coral hosts. Enhanced photosynthesis in relation to accelerating light exposure shows that coral microscale optics exerts a key role on coral photophysiology and the subsequent degree of radiative stress during coral bleaching.

  13. Disposal of high-activity nuclear wastes

    International Nuclear Information System (INIS)

    Hamilton, E.I.

    1983-01-01

    A discussion is presented on the deep sea ocean disposal for high-activity nuclear wastes. The following topics are covered: effect of ionizing radiation on marine ecosystems; pathways by which radionuclides are transferred to man from the marine environment; information about releases of radioactivity to the sea; radiological protection; storage and disposal of radioactive wastes and information needs. (U.K.)

  14. Optical bleaching of bismuth implanted silica glass: A threshold effect

    International Nuclear Information System (INIS)

    Park, S.Y.; Magruder, R.H. III; Weeks, R.A.

    1992-01-01

    The near surface regions of high purity silica glass discs, Spectrosil A, were modified by implantation with bismuth ions at 160 key and room temperature. The glasses implanted with a nominal dose of 6x10 16 Bi/cm 2 at ∼5 μA/cm 2 were subsequently bleached with a 5.0 eV KrF pulsed excimer laser. The laser had an average pulse duration of ∼20 ns and repetition rate of 10 Hz. It was found that the bleaching was dependent upon the power density of the laser for a constant total integrated energy. Ion backscattering and optical absorption measurements were made before and after laser irradiation. Large changes in optical density and depth distribution of the implanted ions were observed at power densities of ≥45 mJ/cm 2 -pulse. Onset of threshold for bleaching of silica glass implanted with 6x10 16 Bi/cm 2 at 160 key and at room temperature is between 30 and 45 mJ/cm 2 -pulse

  15. Severity of the 1998 and 2005 bleaching events in Venezuela, southern Caribbean

    Directory of Open Access Journals (Sweden)

    Sebastián Rodríguez

    2010-10-01

    Full Text Available This study describes the severity of the 2005 bleaching event at 15 reef sites across Venezuela and compares the 1998 and 2005 bleaching events at one of them. During August and September 2005, bleached corals were first observed on oceanic reefs rather than coastal reefs, affecting 1 to 4% of coral colonies in the community (3 reef sites, n=736 colonies. At that time, however, no bleached corals were recorded along the eastern coast of Venezuela, an area of seasonal upwelling (3 reefs, n=181 colonies. On coastal reefs, bleaching started in October but highest levels were reached in November 2005 and January 2006, when 16% of corals were affected among a wide range of taxa (e.g. scleractinians, octocorals, Millepora and zoanthids. In the Acropora habitats of Los Roques (an oceanic reef, no bleached was recorded in 2005 (four sites, n=643 colonies. At Cayo Sombrero, a coastal reef site, bleaching was less severe in 1998 than in 2005 (9% of the coral colonies involving 2 species vs. 26% involving 23 species, respectively. Our results indicate that bleaching was more severe in 2005 than in 1998 on Venezuelan reefs; however, no mass mortality was observed in either of these two events. Rev. Biol. Trop. 58 (Suppl. 3: 189-196. Epub 2010 October 01.En este estudio se describe la severidad del evento de blanqueamiento del 2005 en 15 arrecifes coralinos de Venezuela, y se compara con el ocurrido en 1998 para uno de esos arrecifes. Los primeros corales blanqueados se observaron en agosto y septiembre 2005, en arrecifes oceánicos en lugar de costeros, afectando entre 1 y 4% de las colonias coralinas (3 arrecifes, n= 736 colonias. Para ese momento, tampoco se había detectado blanqueamiento en áreas oceánicas de la costa este de Venezuela (3 arrecifes, n= 181 colonias, donde ocurre una surgencia estacional. En arrecifes costeros, el blanqueamiento comenzó en octubre pero alcanzó su máximo entre noviembre 2005 y enero 2006, afectando hasta el 16% de

  16. The role of bound chlorine in the brightness reversion of bleached hardwood kraft pulp

    Directory of Open Access Journals (Sweden)

    Kátia Maria Morais Eiras

    2009-01-01

    Full Text Available Our previous paper showed fragmentary evidence that pulp brightness reversion may be negatively affected by its organically bound chlorine (OX content. A thorough investigation on eucalyptus kraft pulp led to the conclusion that OX increases reversion of certain pulps but this trend is not universal. Alkaline bleaching stages decrease reversion regardless of pulp OX content. Pulps bleached with high temperature chlorine dioxide revert less than those bleached with conventional chlorine dioxide in sequences ending with a chlorine dioxide stage but similarly in sequences ending with a final peroxide stage. The use of secondary condensate for pulp washing decreases reversion.

  17. Effect of tooth-bleaching on the carbonate concentration in dental enamel by Raman spectroscopy.

    Science.gov (United States)

    Vargas-Koudriavtsev, Tatiana; Herrera-Sancho, Óscar-Andrey

    2017-01-01

    There are not many studies evaluating the effects of surface treatments at the molecular level. The aim of this in vitro study was to analyze the concentration of carbonate molecules in dental enamel by Raman spectroscopy after the application of in-office and home whitening agents. Sixty human teeth were randomly divided into six groups and exposed to three different home bleaching gels (Day White) and three in-office whitening agents (Zoom! Whitespeed and PolaOffice) according to the manufacturer´s instructions. The concentration of carbonate molecules in enamel was measured prior to and during the treatment by means of Raman spectroscopy. Statistical analysis included repeated measures analysis of variance ( p ≤0.05) and Bonferroni pairwise comparisons. At home bleaching agents depicted a decrease in the carbonate molecule. This decrease was statistically significant for the bleaching gel with the highest hydrogen peroxide concentration ( p ≤0,05). In-office whitening agents caused an increase in carbonate, which was significant for all three groups ( p ≤0,05). In-office bleaching gels seem to cause a gain in carbonate of the enamel structure, whilst at-home whitening gels caused a loss in carbonate. Key words: Bleaching, whitening, hydrogen peroxide, carbamide peroxide, Raman spectroscopy, carbonate.

  18. Effect of tooth bleaching agents on protein content and mechanical properties of dental enamel.

    Science.gov (United States)

    Elfallah, Hunida M; Bertassoni, Luiz E; Charadram, Nattida; Rathsam, Catherine; Swain, Michael V

    2015-07-01

    This study investigated the effect of two bleaching agents, 16% carbamide peroxide (CP) and 35% hydrogen peroxide (HP), on the mechanical properties and protein content of human enamel from freshly extracted teeth. The protein components of control and treated enamel were extracted and examined on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Marked reduction of the protein matrix and random fragmentation of the enamel proteins after bleaching treatments was found. The mechanical properties were analyzed with Vickers indentations to characterize fracture toughness, and nanoindentation to establish enamel hardness, elastic modulus and creep deformation. Results indicate that the hardness and elastic modulus of enamel were significantly reduced after treatment with CP and HP. After bleaching, the creep deformation at maximum load increased and the recovery upon unloading reduced. Crack lengths of CP and HP treated enamel were increased, while fracture toughness decreased. Additionally, the microstructures of fractured and indented samples were examined with field emission gun scanning electron microscopy (FEG-SEM) showing distinct differences in the fracture surface morphology between pre- and post-bleached enamel. In conclusion, tooth bleaching agents can produce detrimental effects on the mechanical properties of enamel, possibly as a consequence of damaging or denaturing of its protein components. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  19. 'In vitro' assessment to instrumented indentation hardness tests in enamel of bovine teeth, before and after dental bleaching by laser

    International Nuclear Information System (INIS)

    Britto Junior, Francisco Meira

    2004-01-01

    The laser enamel bleaching is a common used procedure due to its satisfactory esthetic results. The possible changes on the dental structures caused by the bleaching technique are of great importance. The enamel superficial microhardness changes through instrumented indentation hardness on bovine teeth were analyzed in this present study. The samples were divided in two halves, one being the control and the other irradiated with a diode laser (808 nm) or with a Nd:YAG laser (1064 nm) to activate the Whiteness HP bleaching gel (hydrogen peroxide at 35%). It was possible to conclude that there was a statistical significant increase on the enamel superficial microhardness (Group I, sample 1 and Group II, sample 1) despite this increase did not seem to indicate a concern regarding the enamel surface resistance change. There was not a significant statistical change on the enamel microhardness on the other samples. The final conclusion is that there was no superficial enamel morphological change after these treatments. (author)

  20. Monitoring Coral Health to Determine Coral Bleaching Response at High Latitude Eastern Australian Reefs: An Applied Model for A Changing Climate

    Directory of Open Access Journals (Sweden)

    Andrew G. Carroll

    2011-09-01

    Full Text Available Limited information is available on the bleaching susceptibility of coral species that dominate high latitude reefs along the eastern seaboard of Australia. The main aims of this study were to: (i monitor coral health and spatial patterns of coral bleaching response at the Solitary Islands Marine Park (SIMP and Lord Howe Island Marine Park (LHIMP, to determine variability of bleaching susceptibility among coral taxa; (ii predict coral bleaching thresholds at 30 °S and 31.5 °S, extrapolated from published bleaching threshold data; and (iii propose a subtropical northern New South Wales coral bleaching model from biological and physical data. Between 2005 and 2007 minor bleaching was observed in dominant coral families including Pocilloporidae, Poritidae and Dendrophylliidae in the SIMP and Pocilloporidae, Poritidae and Acroporidae (Isopora and Montipora spp. in the LHIMP, with a clear difference in bleaching susceptibility found between sites, both within and between locations. Bleaching susceptibility was highest in Porites spp. at the most offshore island site within the SIMP during summer 2005. Patterns of subtropical family bleaching susceptibility within the SIMP and LHIMP differed to those previously reported for the central Great Barrier Reef (GBR. These differences may be due to a number of factors, including temperature history and/or the coral hosts association with different zooxanthellae clades, which may have lower thermal tolerances. An analysis of published estimates of coral bleaching thresholds from the Caribbean, South Africa, GBR and central and northern Pacific regions suggests that the bleaching threshold at 30–31.5 °S ranges between 26.5–26.8 °C. This predicted threshold was confirmed by an extensive coral bleaching event on the world’s southernmost coral reef at Lord Howe Island, during the 2010 austral summer season. These results imply that dominant coral taxa at subtropical reefs along the eastern Australian

  1. Effect of At-home and In-office Bleaching on Marginal Microleakage in Composite Resin Restorations using Two Adhesive Systems.

    Science.gov (United States)

    Klein, Celso A; da Silva, Douglas; Reston, Eduardo G; Borghetti, Diana Lb; Zimmer, Roberto

    2018-03-01

    The aim of this study is to assess marginal microleakage of cervical cavities restored with composite resins and two different adhesive techniques subjected to at-home and in-office bleaching. In this randomized, blind laboratory experiment, 60 bovine teeth recently extracted were collected and divided into six groups (n = 10 each group). The teeth received cervical cavity preparations (2 mm × 3 mm × 1 mm) with enamel margins. Two different adhesive systems were used (Single Bond 2 and Clearfil SE Bond), in addition to composite resin (Z250). Restored teeth received two different bleaching gels (Opalescence PF and Opalescence Boost). Teeth were thermo-cycled and analyzed under confocal laser scanning microscopy. No significant differences were observed (p > 0.05) in microleakage scores between the two groups not subjected to bleaching nor between the four groups that received bleaching treatment (p > 0.05), regardless of the gel and adhesive system employed. However, when comparing nonbleached with bleached teeth, those not subjected to bleaching showed statistically lower marginal microleakage scores (p bleaching agents used both at-home and in-office, regardless of the adhesive system employed (total-etch or self-etch). Both at-home and in-office bleaching agents have an influence on the adhesive interface of resin restorations, producing changes and inducing marginal leakage.

  2. Radioactive waste characterisation by neutron activation

    International Nuclear Information System (INIS)

    Nicol, Tangi

    2016-01-01

    Nuclear activities produce radioactive wastes classified following their radioactive level and decay time. an accurate characterization is necessary for efficient classification and management. Medium and high level wastes containing long lived radioactive isotopes will be stored in deep geological storage for hundreds of thousands years. at the end of this period, it is essential to ensure that the wastes do not represent any risk for humans and environment, not only from radioactive point of view, but also from stable toxic chemicals. This PhD thesis concerns the characterization of toxic chemicals and nuclear material in radioactive waste, by using neutron activation analysis, in the frame of collaboration between the Nuclear Measurement Laboratory of CEA Cadarache, France, and the Institute of Nuclear Waste Management and Reactor Safety of the research center, FZJ (Forschungszentrum Juelich GmbH), Germany. The first study is about the validation of the numerical model of the neutron activation cell MEDINA (FZJ), using MCNP Monte Carlo transport code. Simulations and measurements of prompt capture gamma rays from small samples measured in MEDINA have been compared for a number of elements of interest (beryllium, aluminum, chlorine, copper, selenium, strontium, and tantalum). The comparison was performed using different nuclear databases, resulting in satisfactory agreement and validating simulation in view of following studies. Then, the feasibility of fission delayed gamma-ray measurements of "2"3"9Pu and "2"3"5U in 225 L waste drums has been studied, considering bituminized or concrete matrixes representative of wastes produced in France and Germany. The delayed gamma emission yields were first determined from uranium and plutonium metallic samples measurements in REGAIN, the neutron activation cell of LMN, showing satisfactory consistency with published data. The useful delayed gamma signals of "2"3"9Pu and "2"3"5U, homogeneously distributed in the 225 L

  3. Characterization plan for the immobilized low-activity waste borehole

    International Nuclear Information System (INIS)

    Reidel, S.P.; Reynolds, K.D.

    1998-03-01

    The US Department of Energy's (DOE's) Hanford Site has the most diverse and largest amounts of radioactive tank waste in the US. High-level radioactive waste has been stored at Hanford in large underground tanks since 1944. Approximately 209,000 m 3 (54 Mgal) of waste are currently stored in 177 tanks. Vitrification and onsite disposal of low activity tank waste (LAW) are embodied in the strategy described in the Tri-Party Agreement. The tank waste is to be retrieved, separated into low- and high-level fractions, and then immobilized by private vendors. The DOE will receive the vitrified waste from private vendors and dispose of the low-activity fraction in the Hanford Site 200 East Area. The Immobilized Low-Activity Waste Disposal Complex (ILAWDC) is part of the disposal complex. This report is a plan to drill the first characterization borehole and collect data at the ILAWDC. This plan updates and revises the deep borehole portion of the characterization plan for the ILAWDC by Reidel and others (1995). It describes data collection activities for determining the physical and chemical properties of the vadose zone and the saturated zone at and in the immediate vicinity of the proposed ILAWDC. These properties then will be used to develop a conceptual geohydrologic model of the ILAWDC site in support of the Hanford ILAW Performance Assessment

  4. Study on the Modification of Bleached Eucalyptus Kraft Pulp Using Birch Xylan

    Science.gov (United States)

    Wenjia Han; Chuanshan Zhao; Thomas Elder; Rendang Yang; Dongho Kim; Yunqiao Pu; Jeffery Hsieh; Arthur J. Ragauskas

    2012-01-01

    In this study, birch xylan was deposited onto elementally chlorine free (ECF) bleached eucalyptus kraft pulp, and the corresponding changes in physical properties were determined. An aqueous 5% birch xylan solution at pH 9 was added to 5 wt% slurry of bleached kraft eucalyptus fibers, with stirring at 70 C for 15 min after which the pH was adjusted to 5–6. The xylan...

  5. Distinguishing method for contamination/radio-activation of radioactive wastes

    International Nuclear Information System (INIS)

    Fukazawa, Takuji; Kato, Keiichiro; Koda, Satoshi.

    1994-01-01

    The present invention concerns a method of distinguishing the contamination/radio-activation of radioactive wastes used in processing wastes generated upon dismantling of exhausted nuclear reactors. Especially, contaminated/radio-activation is distinguished for wastes having openings such as pipes and valves, by utilizing scattering of γ-rays or γ-ray to β-ray ratio. That is, ratio of scattered γ-rays and direct γ-rays or ratio of β-rays and γ-rays from radioactive wastes are measured and compared by a radiation detector, to distinguish whether the radioactive wastes contaminated materials or radio-activated materials. For example, when an object to be measured having an opening is contaminated at the inner side, the radiation detector facing to the opening mainly detects high direct γ-rays emitted from the object to be measured while a radiation detector not facing the opening mainly detects high scattered γ-rays relatively. On the other hand, when the object is a radio-activated material, any of the detectors detect scattered γ-rays, so that they can be distinguished by these ratios. (I.S.)

  6. The Stability of the Giant Clam Holobiont over Time and during Bleaching Stress

    KAUST Repository

    Pappas, Melissa

    2017-12-01

    The stability of marine photosymbiotic holobionts has major implications for the future of coral reef communities. This study aims to describe the stability of the Red Sea giant clam holobiont over the duration of one year and during induced bleaching stress under laboratory thermal manipulations. Tridacnid clams of the species Tridacna maxima were sampled at three reef locations near the central Saudi coast of the Red Sea. Associated Symbiodinium of Red Sea giant clams have previously been described to be part of only Clade A, which suggests a strong specificity in the clam-algal partnership, but specific types and potential shifting of types within this clade have not been examined for giant clams. The results from this study confirm that tridacnid symbiont types shift over time and the change between three A1 types suggests a biological and functional significance of two undescribed A1 Symbiodinium types. Experimental bleaching shows that Red Sea giant clams, although exposed to rather hot temperatures naturally, will bleach at 34°C after two weeks, and severely bleached clams likely will not recover. During bleaching, Symbiodinium types shift as well, and shift more drastically than seasonal shifts during the year. This shifting may be an evolved characteristic of the giant clam to aid in surviving major changes in the environment. However, more research is needed to determine if these holobionts are capable of keeping up with the global forecast of warming in reef environments.

  7. Neutron Activation analysis of waste water

    International Nuclear Information System (INIS)

    Hernandez H, V.

    1997-01-01

    An instrumental neutron activation analysis for the simultaneous determination of chlorine, bromine, sodium, manganese, cobalt, copper, chromium, zinc, nickel, antimony and iron in waste water is described. They were determined in waste water samples under normal conditions by non-destructive neutron activation simultaneously using a suitable monostandard method. Standardized water samples were used and irradiated in polyethylene ampoules at a neutron flux of 10 13 cm -2 s -1 for periods of 1 minute, 1 and 10 hours. A Ge hyperpure detector was used for your activity determination, with count times of 60, 180, 300 and 600 seconds. The obtained results show than the method can be utilized for the determination of this elements without realize anything previous treatment of the samples. (Author)

  8. Mixed phase-amplitude holographic gratings recorded in bleached silver halide materials

    International Nuclear Information System (INIS)

    Neipp, C.; Pascual, C.; Belendez, A.

    2002-01-01

    The coupled wave theory of Kogelnik has given a well-established basis for the comprehension of how light propagates inside a volume hologram. This theory gives a good approximation for the diffraction efficiency of both volume phase holograms and volume absorption holograms. Mixed holograms (phase and absorption) have also been dealt with from the point of view of the coupled wave theory. In this paper we use Kogelnik's coupled wave theory to give quantitative information about the mechanisms which produce mixed gratings in photographic emulsions. In particular, we demonstrate that mixed amplitude-phase gratings are recorded on photographic emulsions when fixation-free bleaching techniques are used to obtain volume holograms. We will prove that the oxidation products of the bleach can give rise to an absorption modulation at high values of exposure and high concentrations of potassium bromide in the bleach bath. We will also give quantitative data regarding the absorption created by these oxidation products. (author)

  9. Coral bleaching and ocean ''hot spots''

    Energy Technology Data Exchange (ETDEWEB)

    Goreau, T.J. (Global Coral Reef Alliance, Chappaqua, NY (United States)); Hayes, R.L. (Howard Univ., Washington, DC (United States). College of Medicine)

    1994-05-01

    Global sea-surface temperature maps show that mass coral-reef bleaching episodes between 1983 and 1991 followed positive anomalies more than 1 deg C above long-term monthly averages (''hot spots'') during the preceding warm season. Irregular formation, movement, and disappearance of hot spots make their detailed long-term prediction impossible, but they can be tracked in real time from satellite data. Monitoring of ocean hot spots and of coral bleaching is needed if the Framework Convention of Climate Change is to meet its goal of protecting the most temperature sensitive ecosystems. 47 refs, 3 figs

  10. Desire for tooth bleaching and treatment performed in Brazilian adults: findings from a birth cohort.

    Science.gov (United States)

    Silva, Fernando Barcellos da; Chisini, Luiz Alexandre; Demarco, Flávio Fernando; Horta, Bernardo Lessa; Correa, Marcos Britto

    2018-03-08

    Population-based studies estimating the prevalence of tooth bleaching desire or the percentage of individuals who had performed this treatment are rare. Thus, the aim of this study was to evaluate the desire to perform tooth bleaching and the prevalence of adult individuals who had performed the treatment and investigate the association of these outcomes. A subsample (n = 536) of the 1982 Pelotas birth cohort in southern Brazil was investigated at the ages 15, 24 and 31 by clinical examinations and interviews. The prevalence of bleaching at 31 years was 15.6% [95%CI 12.6-18.9] while 85.9% [95%CI 82.7-88.7] reported they desired the treatment. Multivariate Poisson regression analysis showed that individuals who have visited the dentist within the last year showed a treatment prevalence ratio (PR) 2.31 times [95%CI 1.40-3.83] higher compared with those who had the last dental visit more than a year before the interview. Similarly, individuals with smoking habits presented an elevated PR of 1.60 [95%CI 1.00-2.55], and the low-income trajectory group showed the largest PR of desire for tooth bleaching (1.17 [95%CI 1.07-1.28]). Moreover, individuals from the high-risk caries trajectory group presented a higher prevalence of desire for tooth bleaching than individuals from low caries trajectory group. Individuals who have declared being "dissatisfied" with their dental color presented a prevalence of desire for tooth bleaching 16% greater than "satisfied" ones. Thus, the present findings confirm that tooth bleaching has become a frequently desired dental treatment to improve dental aesthetics in the population and a considerable rate of adults has performed the treatment.

  11. Change in algal symbiont communities after bleaching, not prior heat exposure, increases heat tolerance of reef corals.

    Science.gov (United States)

    Silverstein, Rachel N; Cunning, Ross; Baker, Andrew C

    2015-01-01

    Mutualistic organisms can be particularly susceptible to climate change stress, as their survivorship is often limited by the most vulnerable partner. However, symbiotic plasticity can also help organisms in changing environments by expanding their realized niche space. Coral-algal (Symbiodinium spp.) symbiosis exemplifies this dichotomy: the partnership is highly susceptible to 'bleaching' (stress-induced symbiosis breakdown), but stress-tolerant symbionts can also sometimes mitigate bleaching. Here, we investigate the role of diverse and mutable symbiotic partnerships in increasing corals' ability to thrive in high temperature conditions. We conducted repeat bleaching and recovery experiments on the coral Montastraea cavernosa, and used quantitative PCR and chlorophyll fluorometry to assess the structure and function of Symbiodinium communities within coral hosts. During an initial heat exposure (32 °C for 10 days), corals hosting only stress-sensitive symbionts (Symbiodinium C3) bleached, but recovered (at either 24 °C or 29 °C) with predominantly (>90%) stress-tolerant symbionts (Symbiodinium D1a), which were not detected before bleaching (either due to absence or extreme low abundance). When a second heat stress (also 32 °C for 10 days) was applied 3 months later, corals that previously bleached and were now dominated by D1a Symbiodinium experienced less photodamage and symbiont loss compared to control corals that had not been previously bleached, and were therefore still dominated by Symbiodinium C3. Additional corals that were initially bleached without heat by a herbicide (DCMU, at 24 °C) also recovered predominantly with D1a symbionts, and similarly lost fewer symbionts during subsequent thermal stress. Increased thermotolerance was also not observed in C3-dominated corals that were acclimated for 3 months to warmer temperatures (29 °C) before heat stress. These findings indicate that increased thermotolerance post-bleaching resulted from

  12. A New Perspective: Assessing the Spatial Distribution of Coral Bleaching with Unmanned Low Altitude Remote Sensing Systems

    Science.gov (United States)

    Levy, J.; Franklin, E. C.; Hunter, C. L.

    2016-12-01

    Coral reefs are biodiversity hotspots that are vital to the function of global economic and biological processes. Coral bleaching is a significant contributor to the global decline of reefs and can impact an expansive reef area over short timescales. In order to understand the dynamics of coral bleaching and how these stress events impact reef ecosystems, it is important to conduct rapid bleaching surveys at functionally important spatial scales. Due to the inherent heterogeneity, size, and in some cases, remoteness of coral reefs, it is difficult to routinely monitor coral bleaching dynamics before, during, and after bleaching. Additionally, current in situ survey methods only collect snippets of discrete reef data over small reef areas, which are unable to accurately represent the reef as a whole. We present a new technique using small unmanned aerial systems (sUAS) as cost effective, efficient monitoring tools that target small to intermediate-scale reef dynamics to understand the spatial distribution of bleached coral colonies during the 2015 bleaching event on patch reefs in Kaneohe Bay, Oahu. Overlapping low altitude aerial images were collected at four reefs during the bleaching period and processed using Structure-from-Motion techniques to produce georeferenced and spatially accurate orthomosaics of complete reef areas. Mosaics were analyzed using manual and heuristic neural network classification schemes to identify comprehensive populations of bleached and live coral on each patch reef. We found that bleached colonies had random and clumped distributions on patch reefs in Kaneohe Bay depending on local environmental conditions. Our work demonstrates that sUAS provide a low cost, efficient platform that can rapidly and repeatedly collect high-resolution imagery (1 cm/pixel) and map large areas of shallow reef ecosystems (5 hectares). This study proves the feasibility of utilizing sUAS as a tool to collect spatially rich reef data that will provide reef

  13. Guest–host interactions in the alkaline bleaching of ...

    Indian Academy of Sciences (India)

    Administrator

    cyclodextrin on the bleaching rates of triphenylmethane dyes crystal violet (CV), malachite green (MG) and rosaniline. (RA) have been investigated in alkaline medium with a view to understand the guest–host interaction in these system. 2.

  14. CHEMICAL COMPOSITION, CRYSTALLINITY, AND THERMAL DEGRADATION OF BLEACHED AND UNBLEACHED KENAF BAST (Hibiscus cannabinus PULP AND NANOFIBERS

    Directory of Open Access Journals (Sweden)

    Mehdi Jonoobi

    2009-05-01

    Full Text Available Kenaf (Hibiscus cannabinus nanofibers were isolated from unbleached and bleached pulp by a combination of chemical and mechanical treatments. The chemical methods were based on NaOH-AQ (anthraquinone and three-stage bleaching (DEpD processes, whereas the mechanical techniques involved refining, cryo-crushing, and high-pressure homogenization. The size and morphology of the obtained fibers were characterized by environmental scanning electron microscopy (ESEM and transmission electron microscopy (TEM, and the studies showed that the isolated nanofibers from unbleached and bleached pulp had diameters between 10-90 nm, while their length was in the micrometer range. Fourier transform infrared (FTIR spectroscopy demonstrated that the content of lignin and hemicellulose decreased in the pulping process and that lignin was almost completely removed during bleaching. Moreover, thermogravimetric analysis (TGA indicated that both pulp types as well as the nanofibers displayed a superior thermal stability as compared to the raw kenaf. Finally, X-ray analyses showed that the chemo-mechanical treatments altered the crystallinity of the pulp and the nanofibers: the bleached pulp had a higher crystallinity than its unbleached counterpart, and the bleached nanofibers presented the highest crystallinity of all the investigated materials.

  15. Post-bleaching coral community change on southern Maldivian reefs: is there potential for rapid recovery?

    Science.gov (United States)

    Perry, C. T.; Morgan, K. M.

    2017-12-01

    Given the severity of the 2016 global bleaching event, there are major questions about how quickly reef communities will recover. Here, we explore the ecological and physical structural changes that occurred across five atoll interior reefs in the southern Maldives using data collected at 6 and 12 months post-bleaching. Following initial severe coral mortality, further minor coral mortality had occurred by 12 months post-bleaching, and coral cover is now low (transitions to rubble-dominated states will occur in the near future. Juvenile coral densities in shallow fore-reef habitats are also exceptionally low (<6 individuals m-2), well below those measured 9-12 months following the 1998 bleaching event, and below recovery thresholds identified on other Indian Ocean reefs. Our findings suggest that the physical structure of these reefs will need to decline further before effective recruitment and recovery can begin.

  16. Effects of the Ratio between Pigment and Bleaching Gel on the Fracture Resistance and Dentin Microhardness of endodontically treated Teeth.

    Science.gov (United States)

    Galloza, Marina Og; Jordão-Basso, Keren Cf; Bandeca, Matheus C; Costa, Samuel O; Borges, Alvaro H; Tonetto, Mateus R; Tirintan, Fabio C; Keine, Kátia C; Kuga, Milton C

    2017-11-01

    The aim of this study was to evaluate the effects of bleaching gel using 35% hydrogen peroxide (HP), associated with red carmine pigment (RC), in the 3:1 or 1:1 ratio, on fracture resistance and dentin microhardness of endodontically treated teeth. A total of 40 lower incisors were endodontically treated and divided into four groups (n = 10), according to the bleaching protocol: G1 (HP3), 35% HP + RC (3:1); G2 (HP1), 35% HP + RC (1:1); G3 (positive), 38% HP; and G4 (negative), unbleached. Four dental bleaching sessions were performed. The dental crowns were restored after the last session and submitted to the fracture resistance test. Totally, 60 specimens from the endodontically treated lower incisor crowns were prepared to evaluate the effects on dentin microhardness. The analysis was measured (in Knoop) prior to and after the last dental bleaching session using similar bleaching protocols. G2 presented the lowest fracture resistance (p 0.05). No difference was observed in the reduction of dentin microhardness among the groups (p > 0.05). A 1:1 ratio (bleaching gel:pigment) caused a significant fracture resistance reduction in relation to the other protocols. No effect on the dentin microhardness reduction was observed. The pigment addition to the bleaching agent accelerates the bleaching chemical reaction. However, no studies have evaluated the ideal proportion to optimize tooth bleaching.

  17. Skin bleaching: highlighting the misuse of cutaneous depigmenting agents.

    Science.gov (United States)

    Dadzie, O E; Petit, A

    2009-07-01

    Hydroquinone and other cutaneous depigmenting agents are widely used by dermatologists to treat pigmentary disorders. On 29 August 2006, the US Food and Drug Administration (FDA) published a monograph in the US Federal Register proposing to ban all hydroquinone products that have not been approved via a New Drug Application process. Reports in the scientific literature on the occurrence of exogenous ochronosis, in relation to the use of hydroquinone, was one of the concerns expressed by the FDA in relation to this agent. However, a review of the English-language scientific literature reveals that most of the reported cases of hydroquinone-induced exogenous ochronosis occurs in Africa, where the cultural practice of skin bleaching is highly prevalent. Skin bleaching is the practice of applying hydroquinone and/or other depigmenting agents to specific or widespread areas of the body, the primary function being to lighten normally dark skin. This practice typically occurs in men and women with Fitzpatrick skin phototypes IV to VI. It is a dangerous practice associated with a diverse range of side-effects, including mercury poisoning. Thus, this current discussion within the dermatological community on the safety of hydroquinone provides a unique opportunity to raise awareness about skin bleaching.

  18. Efficacy of detergent and water versus bleach for disinfection of direct contact ophthalmic lenses.

    Science.gov (United States)

    Abbey, Ashkan M; Gregori, Ninel Z; Surapaneni, Krishna; Miller, Darlene

    2014-06-01

    Although manufacturers recommend cleaning ophthalmic lenses with detergent and water and then with a specific disinfectant, disinfectants are rarely used in ophthalmic practices. The aim of this pilot study was to evaluate the efficacy of detergent and water versus that of bleach, a recommended disinfectant, to eliminate common ocular bacteria and viruses from ophthalmic lenses. Three bacterial strains (Staphylococcus epidermidis, Corynebacterium straitum, and methicillin-resistant Staphylococcus aureus and 2 viral strains (adenovirus and herpes simplex virus [HSV] type-1) were individually inoculated onto 20 gonioscopy and laser lenses. The lenses were washed with detergent and water and then disinfected with 10% bleach. All the lenses were cultured after inoculation, after washing with detergent and water, and after disinfecting with the bleach. Bacterial cultures in thioglycollate broth were observed for 3 weeks, and viral cultures were observed for 2 weeks. The presence of viruses was also detected by multiplex polymerase chain reaction (PCR). All 20 lenses inoculated with S. epidermidis, C. straitum, adenovirus, and HSV-1 showed growth after inoculation but no growth after washing with detergent/water and after disinfecting with the bleach. All lenses showed positive HSV and adenovirus PCR results after inoculation and negative PCR results after washing with detergent/water and after disinfecting with bleach. All methicillin-resistant S. aureus-contaminated lenses showed growth after inoculation and no growth after washing with detergent and water. However, 1 lens showed positive growth after disinfecting with bleach. Cleaning with detergent and water seemed to effectively eliminate bacteria and viruses from the surface of contaminated ophthalmic lenses. Further studies are warranted to design practical disinfection protocols that minimize lens damage.

  19. Molecular analysis of tooth enamel by Raman spectroscopy after treatment with bleaching agents at different concentrations

    International Nuclear Information System (INIS)

    Duran Sedo, Randall; Obando Rosabal, Sofia; Saenz Bonilla, Paola; Soto Aguilar, Calendy; Vasquez Rodriguez, Amaya

    2014-01-01

    The changes in the concentration of the v1 phosphate molecule of the surface of dentin enamel are treated and researched with bleaching agents of chemical activation to basis of hydrogen peroxide than 9,5% and 14% and carbamide peroxide than 38%, for a period of 28 days. Raman spectroscopy was used and 30 dental pieces extracted, of which, were to be free of blemishes and pigmentations, without possessing fractures of the enamel, decay nor any other type of defect. The Raman spectrum was obtained of each dental piece prior to the application of bleaching agents. The specimens were separated into three experimental groups according to the concentration of whitening. The concentration of the v1 phosphate molecule was measured in the tooth enamel to the second and fourth week of treatment. In addition, ANOVA was performed for respective measurements (p≤0.05). A reduction of the v1 phosphate molecule were observed during and after the bleaching process in the experimental groups that have used of hydrogen peroxide to 14% and carbamide peroxide 38%. In the group of hydrogen peroxide to 9,5% has remained unproven a significant reduction. Within the limitations of this study is concluded that the bleaching agent causes a loss of v1 phosphate. This loss has been greater in the whitening of higher concentration. In spite, that the possible effect remineralizing of the saliva on a teeth whitening process has been unevaluated, it is recommended using during and after the treatment, toothpastes, mouthwashes, chewing gums, dental floss, among others, that contain ACP to help to cushion the potential loss of phosphate from tooth enamel. (author) [es

  20. Wastes from selected activities in two light-water reactor fuel cycles

    International Nuclear Information System (INIS)

    Palmer, C.R.; Hill, O.F.

    1980-07-01

    This report presents projected volumes and radioactivities of wastes from the production of electrical energy using light-water reactors (LWR). The projections are based upon data developed for a recent environmental impact statement in which the transuranic wastes (i.e., those wastes containing certain long-lived alpha emitters at concentrations of at least 370 becquerels, or 10 nCi, per gram of waste) from fuel cycle activities were characterized. In addition, since the WG.7 assumed that all fuel cycle wastes except mill tailings are placed in a mined geologic repository, the nontransuranic wastes from several activities are included in the projections reported. The LWR fuel cycles considered are the LWR, once-through fuel cycle (Strategy 1), in which spent fuel is packaged in metal canisters and then isolated in geologic formations; and the LWR U/Pu recycle fuel cycle (Strategy 2), wherein spent fuel is reprocessed for recovery and recycle of uranium and plutonium in LWRs. The wastes projected for the two LWR fuel cycles are summarized. The reactor operations and decommissioning were found to dominate the rate of waste generation in each cycle. These activities account for at least 85% of the fuel cycle waste volume (not including head-end wastes) when normalized to per unit electrical energy generated. At 10 years out of reactor, however, spent fuel elements in Strategy 1 represent 98% of the fuel cycle activity but only 4% of the volume. Similarly, the packaged high-level waste, fuel hulls and hardware in Strategy 2 concentrate greater than 95% of the activity in 2% of the waste volume