Cooperative Spatial Retreat for Resilient Drone Networks †

Science.gov (United States)

Kang, Jin-Hyeok; Kwon, Young-Min; Park, Kyung-Joon

2017-01-01

Drones are broadening their scope to various applications such as networking, package delivery, agriculture, rescue, and many more. For proper operation of drones, reliable communication should be guaranteed because drones are remotely controlled. When drones experience communication failure due to bad channel condition, interference, or jamming in a certain area, one existing solution is to exploit mobility or so-called spatial retreat to evacuate them from the communication failure area. However, the conventional spatial retreat scheme moves drones in random directions, which results in inefficient movement with significant evacuation time and waste of battery lifetime. In this paper, we propose a novel spatial retreat technique that takes advantage of cooperation between drones for resilient networking, which is called cooperative spatial retreat (CSR). Our performance evaluation shows that the proposed CSR significantly outperforms existing schemes. PMID:28467390

Comparison of the amount of apical debris extrusion associated with different retreatment systems and supplementary file application during retreatment process.

Science.gov (United States)

Çiçek, Ersan; Koçak, Mustafa Murat; Koçak, Sibel; Sağlam, Baran Can

2016-01-01

The type of instrument affects the amount of debris extruded. The aim of this study was to compare the effect of retreatment systems and supplementary file application on the amount of apical debris extrusion. Forty-eight extracted mandibular premolars with a single canal and similar length were selected. The root canals were prepared with the ProTaper Universal system with a torque-controlled engine. The root canals were dried and were obturated using Gutta-percha and sealer. The specimens were randomly divided into four equal groups according to the retreatment procedures (Group 1, Mtwo retreatment files; Group 2, Mtwo retreatment files + Mtwo rotary file #30 supplementary file; Group 3, ProTaper Universal retreatment (PTUR) files; and Group 4, PTUR files + ProTaper F3 supplementary file). The extruded debris during instrumentation were collected into preweighed Eppendorf tubes. The amount of apically extruded debris was calculated by subtracting the initial weight of the tube from the final weight. Three consecutive weights were obtained for each tube. No statistically significant difference was found in the amount of apically extruded debris between Groups 1 and 3 (P = 0.590). A significant difference was observed between Groups 1 and 2 (P file significantly increased the amount of apically extruded debris.

An improved synthesis of carbon-14 labelled carboxylic acids from carbon-14 labelled amino acids

International Nuclear Information System (INIS)

Ramamurthy, T.V.; Ravi, S.; Viswanathan, K.V.

1988-01-01

Various carbon-14 labelled amino acids including the aromatic ones viz., tyrosine, phenylalanine and tryptophan are converted to the corresponding carboxylic acids in high yield (70-90%) on a micromolar scale synthesis by reaction with hydroxyl-amine-O-sulphonic acid and in a short reaction time. The improvement in yield has been achieved by using aqeuous alcohol as solvent in lieu of water alone as the medium of reaction. (author)

Formation of organic acids from trace carbon in acidic oxidizing media

International Nuclear Information System (INIS)

Terrassier, C.

2003-01-01

Carbon 14 does not fully desorb as CO 2 during the hot concentrated nitric acid dissolution step of spent nuclear fuel reprocessing: a fraction is entrained in solution into the subsequent process steps as organic species. The work described in this dissertation was undertaken to identify the compounds arising from the dissolution in 3 N nitric acid of uranium carbides (selected as models of the chemical form of carbon 14 in spent fuel) and to understand their formation and dissolution mechanism. The compounds were present at traces in solution, and liquid-solid extraction on a specific stationary phase (porous graphite carbon) was selected to concentrate the monoaromatic poly-carboxylic acids including mellitic acid, which is mentioned in the literature but has not been formally identified. The retention of these species and of oxalic acid - also cited in the literature - was studied on this stationary phase as a function of the mobile phase pH, revealing an ion exchange retention mechanism similar to the one observed for benzyltrimethylammonium polystyrene resins. The desorption step was then optimized by varying the eluent pH and ionic strength. Mass spectrometry analysis of the extracts identified acetic acid, confirmed the presence of mellitic acid, and revealed compounds of high molecular weight (about 200 g/mol); the presence of oxalic acid was confirmed by combining gas chromatography and mass spectrometry. Investigating the dissolution of uranium and zirconium carbides in nitric acid provided considerable data on the reaction and suggested a reaction mechanism. The reaction is self-catalyzing via nitrous acid, and the reaction rate de pends on the acidity and nitrate ion concentration in solution. Two uranium carbide dissolution mechanisms are proposed: one involves uranium at oxidation state +IV in solution, coloring the dissolution solution dark green, and the other assumes that uranium monocarbide is converted to uranium oxide. The carboxylic acid

Production of Odd-Carbon Dicarboxylic Acids in Escherichia coli Using an Engineered Biotin-Fatty Acid Biosynthetic Pathway.

Science.gov (United States)

Haushalter, Robert W; Phelan, Ryan M; Hoh, Kristina M; Su, Cindy; Wang, George; Baidoo, Edward E K; Keasling, Jay D

2017-04-05

Dicarboxylic acids are commodity chemicals used in the production of plastics, polyesters, nylons, fragrances, and medications. Bio-based routes to dicarboxylic acids are gaining attention due to environmental concerns about petroleum-based production of these compounds. Some industrial applications require dicarboxylic acids with specific carbon chain lengths, including odd-carbon species. Biosynthetic pathways involving cytochrome P450-catalyzed oxidation of fatty acids in yeast and bacteria have been reported, but these systems produce almost exclusively even-carbon species. Here we report a novel pathway to odd-carbon dicarboxylic acids directly from glucose in Escherichia coli by employing an engineered pathway combining enzymes from biotin and fatty acid synthesis. Optimization of the pathway will lead to industrial strains for the production of valuable odd-carbon diacids.

Formation and interpretation of eskers beneath retreating ice sheets

Science.gov (United States)

Creyts, T. T.; Hewitt, I.

2017-12-01

The retreat of the ice sheets during the Pleistocene left large and spectacular subglacial features exposed. Understanding these features gives us insight into how the ice sheets retreated, how meltwater influenced retreat, and can help inform our understanding of potential future rates of ice sheet retreat. Among these features, eskers, long sinuous ridges primarily composed of clastic sediments, lack a detailed explanation of how surface melt rates and ice sheet retreat rates influence their growth and spatial distribution. Here, we develop a theory for esker formation based on the initial work of Rothlisberger modified for sediment transport and inclusion of surface meltwater forcing. The primary subglacial ingredients include water flow through subglacial tunnels with the addition of mass balances for sediment transport. We show how eskers when water flow slows below a critical stress for sediment motion. This implies that eskers are deposited in a localized region near the snout of the ice sheet. Our findings suggest that very long eskers form sequentially as the ice front retreats. The position of the esker follows the path of the channel mouth through time, which does not necessarily coincide with the instantaneous route of the feeding channel. However, in most cases, we expect those locations to be similar. The role of surface meltwater and the climatology associated with the forcing is crucial to the lateral spacing of the eskers. We predict that high surface melt rates lead to narrower catchments but that the greater extent of the ablation area means that channels are likely larger. At the same time, for a given channel size (and hence sediment flux), the size of a deposited esker depends on a margin retreat rate. Hence, the size of the eskers is related delicately to the balance between surface melt rates and margin retreat rates. We discuss how our theory can be combined with observed esker distributions to infer the relationship between these two rates

2017 Rapid Retreat Of Thwaites Glacier

Science.gov (United States)

Milillo, P.; Rignot, E. J.; Mouginot, J.; Scheuchl, B.

2017-12-01

We employ data from the second generation of SAR systems e.g. the Italian COSMO- SkyMed (CSK) constellation and the German TanDEM-X (TDX) formation to monitor grounding line retreat using short repeat-time interferometry and accurate InSAR DEM on Thwaites glacier in the Amundsen Sea Embayment (ASE), West Antarctica. The ASE is a marine-based ice sheet with a retrograde bed containing enough ice to raise global sea level by 120 cm. Several studies have inferred the mechanical properties of portions of ASE using observationally constrained numerical models, but these studies offer only temporal snapshots of basal mechanics owing to a dearth of observational time series. Prior attempts of grounding lines mapping have been limited because few space-borne SAR missions offer the short-term repeat pass capability required to map the differential vertical displacement of floating ice at tidal frequencies with sufficient detail to resolve grounding line boundaries in areas of fast ice deformation. Using 1-day CSK repeat pass data and TDX DEMs, we collected frequent, high-resolution grounding line measurements of Thwaites glaciers spanning 2015-2017. We compare the results with ERS data spanning 1996-2011, and Sentinel-1a 2014-2015 data. Between 2011 and 2017 we observe a maximum retreat of 5-7 km across the main Thwaites glacier tongue and Thwaites Eastern ice shelf (TEIS) corresponding to an increased retreat rate of 0.5 km/yr. Grounding line retreat has been fueled by the enhanced intrusion of warm, salty, subsurface ocean water of circumpolar deep water origin onto the continental shelf, beneath the floating ice shelf, to reach the glacier grounding zone and melt it from below at rates varying from 50 to 150 m/yr. The retreat rate varies depending on the magnitude of ice melt by the ocean, the rate of ice thinning and the shape of the glacier surface and bed topography.

Comparative evaluation of debris extruded apically by using, Protaper retreatment file, K3 file and H-file with solvent in endodontic retreatment

Directory of Open Access Journals (Sweden)

Chetna Arora

2012-01-01

Full Text Available Aim: The aim of this study was to evaluate the apical extrusion of debris comparing 2 engine driven systems and hand instrumentation technique during root canal retreatment. Materials and Methods: Forty five human permanent mandibular premolars were prepared using the step-back technique, obturated with gutta-percha/zinc oxide eugenol sealer and cold lateral condensation technique. The teeth were divided into three groups: Group A: Protaper retreatment file, Group B: K3, file Group C: H-file with tetrachloroethylene. All the canals were irrigated with 20ml distilled water during instrumentation. Debris extruded along with the irrigating solution during retreatment procedure was carefully collected in preweighed Eppendorf tubes. The tubes were stored in an incubator for 5 days, placed in a desiccator and then re-weighed. Weight of dry debris was calculated by subtracting the weight of the tube before instrumentation and from the weight of the tube after instrumentation. Data was analyzed using Two Way ANOVA and Post Hoc test. Results : There was statistically significant difference in the apical extrusion of debris between hand instrumentation and protaper retreatment file and K3 file. The amount of extruded debris caused by protaper retreatment file and K3 file instrumentation technique was not statistically significant. All the three instrumentation techniques produced apically extruded debris and irrigant. Conclusion: The best way to minimize the extrusion of debris is by adapting crown down technique therefore the use of rotary technique (Protaper retreatment file, K3 file is recommended.

Efficacy of two rotary retreatment systems in removing Gutta-percha and sealer during endodontic retreatment with or without solvent: A comparative in vitro study.

Science.gov (United States)

Bhagavaldas, Moushmi Chalakkarayil; Diwan, Abhinav; Kusumvalli, S; Pasha, Shiraz; Devale, Madhuri; Chava, Deepak Chowdary

2017-01-01

The aim of this in vitro study was to compare the efficacy of two retreatment rotary systems in the removal of Gutta-percha (GP) and sealer from the root canal walls with or without solvent. Forty-eight extracted human mandibular first premolars were prepared and obturated with GP and AH Plus sealer. Samples were then randomly divided into four groups. Group I was retreated with MtwoR rotary system without solvent, Group II was retreated with MtwoR rotary system with Endosolv R as the solvent, Group III with D-RaCe rotary system without solvent, and Group IV with D-RaCe rotary system and Endosolv R solvent. The cleanliness of canal walls was determined by stereomicroscope (×20) and AutoCAD software. Kruskal-Wallis test and Mann-Whitney U-test were used to compare the data. Results showed that none of the retreatment systems used in this study was able to completely remove the root canal filling material. D-RaCe with or without solvent showed significantly ( P > 0.05) less filling material at all levels compared to MtwoR with/without solvent. Within the limitation of the current study, D-RaCe rotary retreatment system is more effective in removing filling material from root canal walls when compared to MtwoR rotary retreatment system.

Carbon-based strong solid acid for cornstarch hydrolysis

Science.gov (United States)

Nata, Iryanti Fatyasari; Irawan, Chairul; Mardina, Primata; Lee, Cheng-Kang

2015-10-01

Highly sulfonated carbonaceous spheres with diameter of 100-500 nm can be generated by hydrothermal carbonization of glucose in the presence of hydroxyethylsulfonic acid and acrylic acid at 180 °C for 4 h. The acidity of the prepared carbonaceous sphere C4-SO3H can reach 2.10 mmol/g. It was used as a solid acid catalyst for the hydrolysis of cornstarch. Total reducing sugar (TRS) concentration of 19.91 mg/mL could be obtained by hydrolyzing 20 mg/mL cornstarch at 150 °C for 6 h using C4-SO3H as solid acid catalyst. The solid acid catalyst demonstrated good stability that only 9% decrease in TRS concentration was observed after five repeat uses. The as-prepared carbon-based solid acid catalyst can be an environmentally benign replacement for homogeneous catalyst.

The health impact of residential retreats: a systematic review.

Science.gov (United States)

Naidoo, Dhevaksha; Schembri, Adrian; Cohen, Marc

2018-01-10

Unhealthy lifestyles are a major factor in the development and exacerbation of many chronic diseases. Improving lifestyles though immersive residential experiences that promote healthy behaviours is a focus of the health retreat industry. This systematic review aims to identify and explore published studies on the health, wellbeing and economic impact of retreat experiences. MEDLINE, CINAHL and PsychINFO databases were searched for residential retreat studies in English published prior to February 2017. Studies were included if they were written in English, involved an intervention program in a residential setting of one or more nights, and included before-and-after data related to the health of participants. Studies that did not meet the above criteria or contained only descriptive data from interviews or case studies were excluded. A total of 23 studies including eight randomised controlled trials, six non-randomised controlled trials and nine longitudinal cohort studies met the inclusion criteria. These studies included a total of 2592 participants from diverse geographical and demographic populations and a great heterogeneity of outcome measures, with seven studies examining objective outcomes such as blood pressure or biological makers of disease, and 16 studies examining subjective outcomes that mostly involved self-reported questionnaires on psychological and spiritual measures. All studies reported post-retreat health benefits ranging from immediately after to five-years post-retreat. Study populations varied widely and most studies had small sample sizes, poorly described methodology and little follow-up data, and no studies reported on health economic outcomes or adverse effects, making it difficult to make definite conclusions about specific conditions, safety or return on investment. Health retreat experiences appear to have health benefits that include benefits for people with chronic diseases such as multiple sclerosis, various cancers, HIV

Porous structure and surface chemistry of phosphoric acid activated carbon from corncob

International Nuclear Information System (INIS)

Sych, N.V.; Trofymenko, S.I.; Poddubnaya, O.I.; Tsyba, M.M.; Sapsay, V.I.; Klymchuk, D.O.; Puziy, A.M.

2012-01-01

Highlights: ► Phosphoric acid activation results in formation of carbons with acidic surface groups. ► Maximum amount of surface groups is introduced at impregnation ratio 1.25. ► Phosphoric acid activated carbons show high capacity to copper. ► Phosphoric acid activated carbons are predominantly microporous. ► Maximum surface area and pore volume achieved at impregnation ratio 1.0. - Abstract: Active carbons have been prepared from corncob using chemical activation with phosphoric acid at 400 °C using varied ratio of impregnation (RI). Porous structure of carbons was characterized by nitrogen adsorption and scanning electron microscopy. Surface chemistry was studied by IR and potentiometric titration method. It has been shown that porosity development was peaked at RI = 1.0 (S BET = 2081 m 2 /g, V tot = 1.1 cm 3 /g), while maximum amount of acid surface groups was observed at RI = 1.25. Acid surface groups of phosphoric acid activated carbons from corncob includes phosphate and strongly acidic carboxylic (pK = 2.0–2.6), weakly acidic carboxylic (pK = 4.7–5.0), enol/lactone (pK = 6.7–7.4; 8.8–9.4) and phenol (pK = 10.1–10.7). Corncob derived carbons showed high adsorption capacity to copper, especially at low pH. Maximum adsorption of methylene blue and iodine was observed for carbon with most developed porosity (RI = 1.0).

Porous structure and surface chemistry of phosphoric acid activated carbon from corncob

Energy Technology Data Exchange (ETDEWEB)

Sych, N.V.; Trofymenko, S.I.; Poddubnaya, O.I.; Tsyba, M.M. [Institute for Sorption and Endoecology Problems, National Academy of Sciences of Ukraine, 13 General Naumov St., 03164 Kyiv (Ukraine); Sapsay, V.I.; Klymchuk, D.O. [M.G. Kholodny Institute of Botany, National Academy of Sciences of Ukraine, 2 Tereshchenkivska St., 01601 Kyiv (Ukraine); Puziy, A.M., E-mail: alexander.puziy@ispe.kiev.ua [Institute for Sorption and Endoecology Problems, National Academy of Sciences of Ukraine, 13 General Naumov St., 03164 Kyiv (Ukraine)

2012-11-15

Highlights: Black-Right-Pointing-Pointer Phosphoric acid activation results in formation of carbons with acidic surface groups. Black-Right-Pointing-Pointer Maximum amount of surface groups is introduced at impregnation ratio 1.25. Black-Right-Pointing-Pointer Phosphoric acid activated carbons show high capacity to copper. Black-Right-Pointing-Pointer Phosphoric acid activated carbons are predominantly microporous. Black-Right-Pointing-Pointer Maximum surface area and pore volume achieved at impregnation ratio 1.0. - Abstract: Active carbons have been prepared from corncob using chemical activation with phosphoric acid at 400 Degree-Sign C using varied ratio of impregnation (RI). Porous structure of carbons was characterized by nitrogen adsorption and scanning electron microscopy. Surface chemistry was studied by IR and potentiometric titration method. It has been shown that porosity development was peaked at RI = 1.0 (S{sub BET} = 2081 m{sup 2}/g, V{sub tot} = 1.1 cm{sup 3}/g), while maximum amount of acid surface groups was observed at RI = 1.25. Acid surface groups of phosphoric acid activated carbons from corncob includes phosphate and strongly acidic carboxylic (pK = 2.0-2.6), weakly acidic carboxylic (pK = 4.7-5.0), enol/lactone (pK = 6.7-7.4; 8.8-9.4) and phenol (pK = 10.1-10.7). Corncob derived carbons showed high adsorption capacity to copper, especially at low pH. Maximum adsorption of methylene blue and iodine was observed for carbon with most developed porosity (RI = 1.0).

Reduced carbon sequestration potential of biochar in acidic soil.

Science.gov (United States)

Sheng, Yaqi; Zhan, Yu; Zhu, Lizhong

2016-12-01

Biochar application in soil has been proposed as a promising method for carbon sequestration. While factors affecting its carbon sequestration potential have been widely investigated, the number of studies on the effect of soil pH is limited. To investigate the carbon sequestration potential of biochar across a series of soil pH levels, the total carbon emission, CO 2 release from inorganic carbon, and phospholipid fatty acids (PLFAs) of six soils with various pH levels were compared after the addition of straw biochar produced at different pyrolysis temperatures. The results show that the acidic soils released more CO 2 (1.5-3.5 times higher than the control) after the application of biochar compared with neutral and alkaline soils. The degradation of both native soil organic carbon (SOC) and biochar were accelerated. More inorganic CO 2 release in acidic soil contributed to the increased degradation of biochar. Higher proportion of gram-positive bacteria in acidic soil (25%-36%) was responsible for the enhanced biochar degradation and simultaneously co-metabolism of SOC. In addition, lower substrate limitation for bacteria, indicated by higher C-O stretching after the biochar application in the acidic soil, also caused more CO 2 release. In addition to the soil pH, other factors such as clay contents and experimental duration also affected the phsico-chemical and biotic processes of SOC dynamics. Gram-negative/gram-positive bacteria ratio was found to be negatively related to priming effects, and suggested to serve as an indicator for priming effect. In general, the carbon sequestration potential of rice-straw biochar in soil reduced along with the decrease of soil pH especially in a short-term. Given wide spread of acidic soils in China, carbon sequestration potential of biochar may be overestimated without taking into account the impact of soil pH. Copyright © 2016 Elsevier B.V. All rights reserved.

Spiral computed tomography assessment of the efficacy of different rotary versus hand retreatment system.

Science.gov (United States)

Mittal, Neelam; Jain, Jyoti

2014-01-01

The purpose of this study was to evaluate the efficacy of nickel-titanium rotary retreatment systems versus stainless steel hand retreatment system with or without solvent for gutta-percha removal during retreatment. Sixty extracted human mandibular molar teeth with single canal in a distal root was prepared with ProTaper rotary nickel-titanium files and obturated with gutta-percha and sealer. The teeth were randomly divided into six groups of 10 specimens in each groups. The volume of filling material before and after retreatment were evaluated in cm(3) using the computed tomography (CT) scanner proprietary software. Maximum amount of filling material removed during retreatment with ProTaper retreatment system with solvent and minimum with hand retreatment system with solvent. None of the technique was 100% effective in removing the filling materials, but the ProTaper retreatment system with solvent was better.

Absorption of carbon dioxide and isotope exchange rate of carbon in a reaction system between carbon dioxide and carbamic acid

International Nuclear Information System (INIS)

Takeshita, Kenji; Kitamoto, Asashi

1985-01-01

The performance of isotope separation of carbon-13 by chemical exchange between carbon dioxide and carbamic acid was studied. The working fluid used in the study was a solution of DNBA, (C 4 H 9 ) 2 NH and n-octane mixture. Factors related to the isotope exchange rate were measured, such as the absorption rate of carbon dioxide into the solution of DNBA and n-octane, the isotope exchange rate and the separation factor in the reaction between CO 2 and carbamic acid. The absorption of CO 2 into the working fluid was the sum of chemical absorption by DNBA and physical absorption by n-octane. The absorption of carbon dioxide into the working fluid was negligible at temperatures over 90 0 C, but increased gradually at lower temperatures. Carbon dioxide was absorbed into DNBA by chemical absorption, and DNBA was converted to carbamic acid by the reaction. The reaction for synthesis and decomposition of carbamic acid was reversible. The separation factor in equilibrium reached a large value at lower temperatures. The isotope exchange rate between gas and liquid was proportional to the product of the concentration of carbamic acid and the concentration of CO 2 by physical absorption. The isotope separation of carbon by chemical exchange reaction is better operated under the conditions of lower temperature and higher pressure. (author)

Production of Odd-Carbon Dicarboxylic Acids in Escherichia coli Using an Engineered Biotin–Fatty Acid Biosynthetic Pathway

Energy Technology Data Exchange (ETDEWEB)

Haushalter, Robert W. [Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Physical Bioscience Division; Phelan, Ryan M. [Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Physical Bioscience Division; Hoh, Kristina M. [Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Physical Bioscience Division; Su, Cindy [Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Physical Bioscience Division; Wang, George [Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Physical Bioscience Division; Baidoo, Edward E. K. [Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Physical Bioscience Division; Keasling, Jay D. [Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Physical Bioscience Division

2017-03-14

Dicarboxylic acids are commodity chemicals used in the production of plastics, polyesters, nylons, fragrances, and medications. Bio-based routes to dicarboxylic acids are gaining attention due to environmental concerns about petroleum-based production of these compounds. Some industrial applications require dicarboxylic acids with specific carbon chain lengths, including odd-carbon species. Biosynthetic pathways involving cytochrome P450-catalyzed oxidation of fatty acids in yeast and bacteria have been reported, but these systems produce almost exclusively even-carbon species. Here in this paper we report a novel pathway to odd-carbon dicarboxylic acids directly from glucose in Escherichia coli by employing an engineered pathway combining enzymes from biotin and fatty acid synthesis. Optimization of the pathway will lead to industrial strains for the production of valuable odd-carbon diacids.

Prevalence of multidrug resistance among retreatment pulmonary tuberculosis cases in a tertiary care hospital, Hyderabad, India

Directory of Open Access Journals (Sweden)

Subhakar Kandi

2013-01-01

Full Text Available Background: India is one of the high tuberculosis (TB burden countries in the world. India ranks second in harboring multi drug resistant (MDR-TB cases. About 50,000 of MDR cases are recorded in retreatment pulmonary TB cases. This study was conducted in a tertiary care facility (Government General and Chest Hospital in Hyderabad, India. Objectives: Toassess: Proportion of the TB patients having MDR-TB at the initiation of retreatment regimen; the prevalence of isoniazid (INH resistance in this geographical area. Materials and Methods: An analytical, observational, prospective cohort study of patients attending the out-patient department from December 2010 to March 2011. Results: Sputum samples from 100 patients were subjected to acid fast bacilli (AFB culture and drug sensitivity testing. Of these, 28 (28% were MDR-TB, 42 (42% were non-MDR-TB and 39% being INH resistance. Conclusions: In conclusion, one third of the retreatment pulmonary TB cases attending a tertiary care institute for TB will be MDR-TB at the initiation of treatment and there is a need to include ethambutol in the continuation phase of new TB case treatment in view of high INH resistance.

Treatment philosophy and retreatment rates following piezoelectric lithotripsy.

Science.gov (United States)

Fegan, J; Camp, L A; Wilson, W T; Miller, G L; Preminger, G M

1993-01-01

Second generation lithotriptors offer the advantage of anesthesia-free fragmentation of renal and ureteral calculi but they frequently require multiple treatments to attain a stone-free status. However, excessive single lithotripsy sessions or multiple treatments may be associated with significant damage to the kidney. For some clinicians a common treatment philosophy involves evaluation of serial plain abdominal films every 24 hours after lithotripsy and immediate retreatment of all patients with incomplete fragmentation. To avoid unnecessary retreatments and, thus, minimize potential renal damage, we prospectively evaluated 100 patients undergoing lithotripsy on a Wolf Piezolith 2300 device. Patients were routinely treated with 4,000 shocks at 1,100 bar. Serial plain abdominal films were obtained at 1 day and 2 weeks after lithotripsy. The need for retreatment was determined by the plain abdominal film results. Additional therapy was considered necessary if there was no stone fragmentation or if residual fragments measured greater than 4 mm. Of the patients whose plain abdominal film at 24 hours indicated the need for a repeat treatment 43% were stone-free on the 2-week film. Thus, these patients were spared an unnecessary treatment by allowing adequate time for the stone fragments to pass spontaneously. Our data suggest that repeat treatments on second generation lithotriptors should not be performed within 24 hours. Rather, the patient should be reevaluated at least 1 to 2 weeks later to avoid unnecessary retreatment with the attendant potential for renal injury. In addition, when comparing the retreatment rates of various lithotriptors, one should also consider the treatment philosophy used at the particular institution and the timing of the radiographic studies used to determine the stone-free status.

Exceptional retreat of Novaya Zemlya's marine-terminating outlet glaciers between 2000 and 2013

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J. R. Carr

2017-09-01

Full Text Available Novaya Zemlya (NVZ has experienced rapid ice loss and accelerated marine-terminating glacier retreat during the past 2 decades. However, it is unknown whether this retreat is exceptional longer term and/or whether it has persisted since 2010. Investigating this is vital, as dynamic thinning may contribute substantially to ice loss from NVZ, but is not currently included in sea level rise predictions. Here, we use remotely sensed data to assess controls on NVZ glacier retreat between 1973/76 and 2015. Glaciers that terminate into lakes or the ocean receded 3.5 times faster than those that terminate on land. Between 2000 and 2013, retreat rates were significantly higher on marine-terminating outlet glaciers than during the previous 27 years, and we observe widespread slowdown in retreat, and even advance, between 2013 and 2015. There were some common patterns in the timing of glacier retreat, but the magnitude varied between individual glaciers. Rapid retreat between 2000 and 2013 corresponds to a period of significantly warmer air temperatures and reduced sea ice concentrations, and to changes in the North Atlantic Oscillation (NAO and Atlantic Multidecadal Oscillation (AMO. We need to assess the impact of this accelerated retreat on dynamic ice losses from NVZ to accurately quantify its future sea level rise contribution.

Promotion of Crystal Growth on Biomass-based Carbon using Phosphoric Acid Treatments

Directory of Open Access Journals (Sweden)

Liwei Yu

2015-02-01

Full Text Available The effect of phosphoric acid treatments on graphitic microcrystal growth of biomass-based carbons was investigated using X-ray diffraction, infrared spectroscopy, and Raman spectroscopy. Although biomass-based carbons are believed to be hard to graphitize even after heat treatments well beyond 2000 °C, we found that graphitic microcrystals of biomass-based carbons were significantly promoted by phosphoric acid treatments above 800 °C. Moreover, twisted spindle-like whiskers were formed on the surface of the carbons. This suggests that phosphorus-containing groups turn graphitic microcrystalline domains into graphite during phosphoric acid treatments. In addition, the porous texture of the phosphoric acid-treated carbon has the advantage of micropore development.

Murdoch Retreats from China

Institute of Scientific and Technical Information of China (English)

Jessy Zhang

2006-01-01

@@ News Corp's Asian flagship enterprise Star Group announced in early June it would sell a 19.9 percent stake in Phoenix Satellite Television to China Mobile. This move is widely interpreted as a signal that Rudolf Murdoch, the helmsman of News Corp,might have lost his patience and could eventually retreat from the Chinese media market.

Porous structure and surface chemistry of phosphoric acid activated carbon from corncob

Science.gov (United States)

Sych, N. V.; Trofymenko, S. I.; Poddubnaya, O. I.; Tsyba, M. M.; Sapsay, V. I.; Klymchuk, D. O.; Puziy, A. M.

2012-11-01

Active carbons have been prepared from corncob using chemical activation with phosphoric acid at 400 °C using varied ratio of impregnation (RI). Porous structure of carbons was characterized by nitrogen adsorption and scanning electron microscopy. Surface chemistry was studied by IR and potentiometric titration method. It has been shown that porosity development was peaked at RI = 1.0 (SBET = 2081 m2/g, Vtot = 1.1 cm3/g), while maximum amount of acid surface groups was observed at RI = 1.25. Acid surface groups of phosphoric acid activated carbons from corncob includes phosphate and strongly acidic carboxylic (pK = 2.0-2.6), weakly acidic carboxylic (pK = 4.7-5.0), enol/lactone (pK = 6.7-7.4; 8.8-9.4) and phenol (pK = 10.1-10.7). Corncob derived carbons showed high adsorption capacity to copper, especially at low pH. Maximum adsorption of methylene blue and iodine was observed for carbon with most developed porosity (RI = 1.0).

Wastewater retreatment and reuse system for agricultural irrigation in rural villages.

Science.gov (United States)

Kim, Minyoung; Lee, Hyejin; Kim, Minkyeong; Kang, Donghyeon; Kim, Dongeok; Kim, YoungJin; Lee, Sangbong

2014-01-01

Climate changes and continuous population growth increase water demands that will not be met by traditional water resources, like surface and ground water. To handle increased water demand, treated municipal wastewater is offered to farmers for agricultural irrigation. This study aimed to enhance the effluent quality from worn-out sewage treatment facilities in rural villages, retreat effluent to meet water quality criteria for irrigation, and assess any health-related and environmental impacts from using retreated wastewater irrigation on crops and in soil. We developed the compact wastewater retreatment and reuse system (WRRS), equipped with filters, ultraviolet light, and bubble elements. A pilot greenhouse experiment was conducted to evaluate lettuce growth patterns and quantify the heavy metal concentration and pathogenic microorganisms on lettuce and in soil after irrigating with tap water, treated wastewater, and WRRS retreated wastewater. The purification performance of each WRRS component was also assessed. The study findings revealed that existing worn-out sewage treatment facilities in rural villages could meet the water quality criteria for treated effluent and also reuse retreated wastewater for crop growth and other miscellaneous agricultural purposes.

Modification of carbon fiber surfaces via grafting with Meldrum's acid

International Nuclear Information System (INIS)

Cuiqin, Fang; Jinxian, Wu; Julin, Wang; Tao, Zhang

2015-01-01

Graphical abstract: - Highlights: • The mechanism of Meldrum's acid modifying carbon fiber surfaces was investigated. • The existing carbonyl groups of carbon fibers were grafted with Meldrum's acid. • The relative content of carboxylic groups on carbon fiber surfaces was increased. • The surfaces of carbon fibers neither etched nor generated coating. • Tensile strength of carbon fibers was preserved after grafting reaction. - Abstract: The mechanism of Meldrum's acid modifying carbon fiber surfaces was investigated in this work. The existing carbonyl groups of carbon fibers were grafted with Meldrum's acid to create carboxylic functionalized surfaces. The surface functionalization effect was detected with X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), atomic force microscopy (AFM), and thermogravimetric analysis (TGA). The XPS results showed that the relative content of carboxylic groups on carbon fiber surfaces was increased from initial 1.41% to 7.84%, however, that of carbonyl groups was decreased from 23.11% to 13.28% after grafting reaction. The SEM, AFM and TGA results indicated that the surfaces of carbon fibers neither etched nor generated coating. The tensile strength of carbon fibers was preserved after grafting reaction according to single fiber tensile strength tests. The fibers were well combined with matrix and the maximal interlaminar shear strength (ILSS) of carbon fiber/epoxy resin composites was sharply increased approximately 74% after functionalization. The effects of acetic acid and sonication on the degree of the surface functionalization were also studied.

Modification of carbon fiber surfaces via grafting with Meldrum's acid

Energy Technology Data Exchange (ETDEWEB)

Cuiqin, Fang; Jinxian, Wu [Beijing Key Laboratory of Electrochemical Process and Technology for Materials, Beijing University of Chemical Technology, Beijing 100029 (China); Julin, Wang, E-mail: wjl@mail.buct.edu.cn [Beijing Key Laboratory of Electrochemical Process and Technology for Materials, Beijing University of Chemical Technology, Beijing 100029 (China); Tao, Zhang [Beijing Institute of Ancient Architecture, Beijing 100050 (China)

2015-11-30

Graphical abstract: - Highlights: • The mechanism of Meldrum's acid modifying carbon fiber surfaces was investigated. • The existing carbonyl groups of carbon fibers were grafted with Meldrum's acid. • The relative content of carboxylic groups on carbon fiber surfaces was increased. • The surfaces of carbon fibers neither etched nor generated coating. • Tensile strength of carbon fibers was preserved after grafting reaction. - Abstract: The mechanism of Meldrum's acid modifying carbon fiber surfaces was investigated in this work. The existing carbonyl groups of carbon fibers were grafted with Meldrum's acid to create carboxylic functionalized surfaces. The surface functionalization effect was detected with X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), atomic force microscopy (AFM), and thermogravimetric analysis (TGA). The XPS results showed that the relative content of carboxylic groups on carbon fiber surfaces was increased from initial 1.41% to 7.84%, however, that of carbonyl groups was decreased from 23.11% to 13.28% after grafting reaction. The SEM, AFM and TGA results indicated that the surfaces of carbon fibers neither etched nor generated coating. The tensile strength of carbon fibers was preserved after grafting reaction according to single fiber tensile strength tests. The fibers were well combined with matrix and the maximal interlaminar shear strength (ILSS) of carbon fiber/epoxy resin composites was sharply increased approximately 74% after functionalization. The effects of acetic acid and sonication on the degree of the surface functionalization were also studied.

Adsorption of pertechnetate ion on various active carbons from mineral acid solutions

International Nuclear Information System (INIS)

Ito, K.

1991-01-01

The adsorption behavior of pertechnetate ion (TcO 4 - ) on active carbon has been studied for various acid solutions, taking as indicative value the distribution coefficient K d of Tc between active carbon surface and solution. In a system where the total anion concentration of the acid and its sodium salt was maintained constant, modifying the pH of the solution proved distinctly to influence the Tc adsorption behavior of active carbon: taking the case of active carbon derived from coconut shell, increasing the acidity raised K d ; around neutrality there occurred a level stage; in the alkali region, K d declined. The rise of K d in the acid region, however, was observed only with active carbon derived from coconut shell, from oil pitch or from saw dust; it failed to occur when the active carbon was derived from coal or from bone. With a hydrochloric acid system, the rise of K d started around 1 M (mol dm -1 ) HCl. Beyond 3 M, on the other hand, a breakthrough occurred, and K d declined with increasing acidity. With a nitric acid system, K d rose from 1 M, and the breakthrough occurred at 2 M. When the adsorption was left to equilibrate beyond 4 h, desorption displacement of TcO 4 - by a coexisting other anion was observed in the case of perchloric acid solutions of concentration above 0.1 M and with sulfuric acid solutions above 0.5 M. (author)

Modification of carbon fiber surfaces via grafting with Meldrum's acid

Science.gov (United States)

Cuiqin, Fang; Jinxian, Wu; Julin, Wang; Tao, Zhang

2015-11-01

The mechanism of Meldrum's acid modifying carbon fiber surfaces was investigated in this work. The existing carbonyl groups of carbon fibers were grafted with Meldrum's acid to create carboxylic functionalized surfaces. The surface functionalization effect was detected with X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), atomic force microscopy (AFM), and thermogravimetric analysis (TGA). The XPS results showed that the relative content of carboxylic groups on carbon fiber surfaces was increased from initial 1.41% to 7.84%, however, that of carbonyl groups was decreased from 23.11% to 13.28% after grafting reaction. The SEM, AFM and TGA results indicated that the surfaces of carbon fibers neither etched nor generated coating. The tensile strength of carbon fibers was preserved after grafting reaction according to single fiber tensile strength tests. The fibers were well combined with matrix and the maximal interlaminar shear strength (ILSS) of carbon fiber/epoxy resin composites was sharply increased approximately 74% after functionalization. The effects of acetic acid and sonication on the degree of the surface functionalization were also studied.

Patients' perceptions, treatment need, and complexity of orthodontic re-treatment

NARCIS (Netherlands)

Ren, Yijin; Boxum, Christo; Sandham, John

The aim of the present study was to investigate the subjective perception and objective treatment need and complexity of patients seeking orthodontic re-treatment. One hundred subjects (66 females, 34 males, age 26.7+/-8.2 years) seeking re-treatment were asked to complete a questionnaire which was

Risk factors for tuberculosis treatment failure, default, or relapse and outcomes of retreatment in Morocco.

Science.gov (United States)

Dooley, Kelly E; Lahlou, Ouafae; Ghali, Iraqi; Knudsen, Janine; Elmessaoudi, My Driss; Cherkaoui, Imad; El Aouad, Rajae

2011-02-28

Patients with tuberculosis require retreatment if they fail or default from initial treatment or if they relapse following initial treatment success. Outcomes among patients receiving a standard World Health Organization Category II retreatment regimen are suboptimal, resulting in increased risk of morbidity, drug resistance, and transmission.. In this study, we evaluated the risk factors for initial treatment failure, default, or early relapse leading to the need for tuberculosis retreatment in Morocco. We also assessed retreatment outcomes and drug susceptibility testing use for retreatment patients in urban centers in Morocco, where tuberculosis incidence is stubbornly high. Patients with smear- or culture-positive pulmonary tuberculosis presenting for retreatment were identified using clinic registries in nine urban public clinics in Morocco. Demographic and outcomes data were collected from clinical charts and reference laboratories. To identify factors that had put these individuals at risk for failure, default, or early relapse in the first place, initial treatment records were also abstracted (if retreatment began within two years of initial treatment), and patient characteristics were compared with controls who successfully completed initial treatment without early relapse. 291 patients presenting for retreatment were included; 93% received a standard Category II regimen. Retreatment was successful in 74% of relapse patients, 48% of failure patients, and 41% of default patients. 25% of retreatment patients defaulted, higher than previous estimates. Retreatment failure was most common among patients who had failed initial treatment (24%), and default from retreatment was most frequent among patients with initial treatment default (57%). Drug susceptibility testing was performed in only 10% of retreatment patients. Independent risk factors for failure, default, or early relapse after initial treatment included male gender (aOR = 2.29, 95% CI 1

Electrochemical formation of hydroxide for enhancing carbon dioxide and acid gas uptake by a solution

Science.gov (United States)

Rau, Gregory Hudson

2014-07-01

A system for forming metal hydroxide from a metal carbonate utilizes a water electrolysis cell having an acid-producing anode and a hydroxyl-producing cathode immersed in a water solution of sufficient ionic content to allow an electric current to pass between the hydroxyl-producing cathode and the acid-producing anode. A metal carbonate is placed in close proximity to the acid-producing anode. A direct current electrical voltage is provided across the acid-producing anode and the hydroxyl-producing cathode sufficient to generate acid at the acid-producing anode and hydroxyl ions at the hydroxyl-producing cathode. The acid dissolves at least part of the metal carbonate into metal and carbonate ions allowing the metal ions to travel toward the hydroxyl-producing cathode and to combine with the hydroxyl ions to form the metal hydroxide. The carbonate ions travel toward the acid-producing anode and form carbonic acid and/or water and carbon dioxide.

Preparation of a Carbon-Based Solid Acid Catalyst by Sulfonating Activated Carbon in a Chemical Reduction Process

Directory of Open Access Journals (Sweden)

Xiao-Yan Liu

2010-10-01

Full Text Available Sulfonated (SO3H-bearing activated carbon (AC-SO3H was synthesized by an aryl diazonium salt reduction process. The obtained material had a SO3H density of 0.64 mmol·g-1 and a specific surface area of 602 m2·g-1. The catalytic properties of AC-SO3H were compared with that of two commercial solid acid catalysts, Nafion NR50 and Amberlyst-15. In a 10-h esterification reaction of acetic acid with ethanol, the acid conversion with AC-SO3H (78% was lower than that of Amberlyst-15 (86%, which could be attributed to the fact that the SO3H density of the sulfonated carbon was lower than that of Amberlyst-15 (4.60 mmol·g-1. However, AC-SO3H exhibited comparable and even much higher catalytic activities than the commercial catalysts in the esterification of aliphatic acids with longer carbon chains such as hexanoic acid and decanoic acid, which may be due to the large specific surface area and mesoporous structures of the activated carbon. The disadvantage of AC-SO3H is the leaching of SO3H group during the reactions.

Boron removal from aqueous solutions by activated carbon impregnated with salicylic acid

International Nuclear Information System (INIS)

Celik, Z. Ceylan; Can, B.Z.; Kocakerim, M. Muhtar

2008-01-01

In this study, the removal of boric acid from aqueous solution by activated carbon impregnated with salicylic acid was studied in batch system. pH, adsorbent amount, initial boron concentration, temperature, shaking rate and salicylic acid film thickness were chosen as parameters. Boron removal efficiencies increased with increasing adsorbent amount, temperature and pH, decreasing initial boron concentration. As thickness of salicylic acid film on activated carbon becomes thin up to 0.088 nm, the efficiency increased, and then, the efficiency decreased with becoming thinner than 0.088 nm of salicylic acid film. Shaking rate was no effect on removal efficiency. In result, it was determined that the use of salicylic acid as an impregnant for activated carbon led to the increase of the amount of boron adsorbed. A lactone ring, being the most appropriate conformation, forms between boric acid and -COOH and -OH groups of salicylic acid

Boron removal from aqueous solutions by activated carbon impregnated with salicylic acid

Energy Technology Data Exchange (ETDEWEB)

Celik, Z. Ceylan [Department of Environmental Engineering, Atatuerk University, Faculty of Engineering, Erzurum (Turkey)], E-mail: zcelik@atauni.edu.tr; Can, B.Z. [Department of Environmental Engineering, Atatuerk University, Faculty of Engineering, Erzurum (Turkey); Kocakerim, M. Muhtar [Department of Chemical Engineering, Atatuerk University, Faculty of Engineering, 25240 Erzurum (Turkey)

2008-03-21

In this study, the removal of boric acid from aqueous solution by activated carbon impregnated with salicylic acid was studied in batch system. pH, adsorbent amount, initial boron concentration, temperature, shaking rate and salicylic acid film thickness were chosen as parameters. Boron removal efficiencies increased with increasing adsorbent amount, temperature and pH, decreasing initial boron concentration. As thickness of salicylic acid film on activated carbon becomes thin up to 0.088 nm, the efficiency increased, and then, the efficiency decreased with becoming thinner than 0.088 nm of salicylic acid film. Shaking rate was no effect on removal efficiency. In result, it was determined that the use of salicylic acid as an impregnant for activated carbon led to the increase of the amount of boron adsorbed. A lactone ring, being the most appropriate conformation, forms between boric acid and -COOH and -OH groups of salicylic acid.

Incidence, outcomes, and risk factors for retreatment after wavefront-optimized ablations with PRK and LASIK.

Science.gov (United States)

Randleman, J Bradley; White, Alfred J; Lynn, Michael J; Hu, Michelle H; Stulting, R Doyle

2009-03-01

To analyze and compare retreatment rates after wavefront-optimized photorefractive keratectomy (PRK) and LASIK and determine risk factors for retreatment. A retrospective chart review was performed to identify patients undergoing PRK or LASIK with the wavefront-optimized WaveLight platform from January 2005 through December 2006 targeted for a piano outcome and to determine the rate and risk factors for retreatment surgery in this population. Eight hundred fifty-five eyes were analyzed, including 70 (8.2%) eyes with hyperopic refractions and 785 (91.8%) eyes with myopic refractions. After initial treatment, 72% of eyes were 20/20 or better and 99.5% were 20/40 or better. To improve uncorrected visual acuity, 54 (6.3%) eyes had retreatments performed. No significant differences in retreatment rates were noted based on age (P = .15), sex (P = .8), eye (P = .3), PRK versus LASIK (P = 1.0), room temperature (P = .1) or humidity (P = .9), and no correlation between retreatment rate and month or season of primary surgery (P = .4). There was no correlation between degree of myopia and retreatment rate. Eyes were significantly more likely to undergo retreatment if they were hyperopic (12.8% vs 6.0%, P = .006) or had astigmatism > or = 1.00 diopter (D) (9.1% vs 5.3%, P = .04). Retreatment rate was 6.3% with the WaveLight ALLEGRETTO WAVE excimer laser. This rate was not influenced by age, sex, corneal characteristics, or environmental factors. Eyes with hyperopic refractions or astigmatism > or = 1.00 D were more likely to undergo retreatment.

Effect of Acid Oxidation on the Dispersion Property of Multiwalled Carbon Nanotubes

Science.gov (United States)

Goh, P. S.; Ismail, A. F.; Aziz, M.

2009-06-01

A means of dispersion of multiwalled carbon nanotube (MWCNT) via mixed acid (HNO3 and H2SO4) oxidation with different treatment durations was investigated through the solubility study of the treated carbon nanotubes in some common solvents. Fourier transformed infrared (FTIR) characterization of the reaction products revealed that the surface of MWCNTs was successfully functionalized with surface acidic groups. The acid-base titration demonstrated that the amount of surface acidic groups increased in parallel with the refluxing duration. The acid modified MWCNTs were found to be well dispersed in polar solvents, such as ethanol and water due to the presence of the hydrophilic acid functional groups on the surface of raw MWCNTs. Such chemical modification of carbon nanotube properties will pave the way towards the realistic applications in the nanotechnology world.

Modeling Antarctic Ice Sheet retreat in warm climates: a historical perspective.

Science.gov (United States)

Pollard, D.; Deconto, R. M.; Gasson, E.

2016-12-01

Early modeling of Antarctic Ice Sheet size vs. climate focused on asymmetry between retreat and growth, with much greater warming needed to cause retreat from full ice cover, due to Height Mass Balance Feedback and albedo feedback. This led to a long-standing model-data conflict, with models needing 1000 to2000 ppmv atmospheric CO2 to produce retreat from full size, vs. proxy data of large ice fluctuations despite much lower CO2 since the Miocene.Subsequent modeling with marine ice physics found that the West Antarctic Ice Sheet could undergo repeated warm-period collapses with realistic past forcing. However, that yields only 3 to 7 m equivalent sea-level rise above modern, compared to 10 to 20 m or more suggested by some geologic data. Large subglacial basins in East Antarctica could be vulnerable to the same processes,but did not retreat in most models due to narrower and shallower sills.After recent modifications, some ice sheet models were able to produce warm-period collapse of major East Antarctic basins, with sea-level rise of up to 15 m. The modifications are (i) hydrofracturing by surface melt, and structural failure of ice cliffs, or (ii) numerical treatment at the grounding line. In these models, large retreat occurs both for past warmintervals, and also for future business-as-usual scenarios.Some interpretations of data in the late Oligocene and Miocene suggest yet larger fluctuations, between 50 to 100% of modern Antarctic size. That would require surface-melt driven retreat of some terrestrial East Antarctic ice, despite the hysteresis issue raised above. A recent study using a coupled climate-ice sheet model found that with a finer climate gridand more frequent coupling exchange, substantial retreat of terrestrial Antarctica can occur with 500 to 840 ppmv CO2, much lower than in earlier models. This will allow meaningful interactions between modeling and deeper-time geologic interpretations since the late Oligocene.

Enhancing the research and publication efforts of health sciences librarians via an academic writing retreat.

Science.gov (United States)

Bullion, John W; Brower, Stewart M

2017-10-01

This case study describes the South Central Chapter of the Medical Library Association (SCC/MLA) initiative to develop an academic writing retreat for members who sought the necessary time and support to advance their research projects toward publication. SCC/MLA staged a dedicated writing retreat to coincide with the organization's 2012, 2013, and 2014 annual meetings. Each cohort met over two days to write and to workshop their peers' manuscripts. Organizers distributed an online survey one month after each retreat to evaluate attendees' perceptions. Three years' worth of writing retreats yielded fourteen peer-reviewed articles and one book chapter. Participants indicated that the retreat helped them meet or exceed their writing goals by offering protected time and a setting conducive to productivity. The format of the retreat is cost effective and easily adaptable for fellow professionals who wish to organize a formal event as a conference offering or simply support a writing group at their home institutions. In SCC/MLA, the retreat revitalized interest in writing and demystified the scholarly publication process.

Carbon composite micro- and nano-tubes-based electrodes for detection of nucleic acids

Directory of Open Access Journals (Sweden)

Huska Dalibor

2011-01-01

Full Text Available Abstract The first aim of this study was to fabricate vertically aligned multiwalled carbon nanotubes (MWCNTs. MWCNTs were successfully prepared by using plasma enhanced chemical vapour deposition. Further, three carbon composite electrodes with different content of carbon particles with various shapes and sizes were prepared and tested on measuring of nucleic acids. The dependences of adenine peak height on the concentration of nucleic acid sample were measured. Carbon composite electrode prepared from a mixture of glassy and spherical carbon powder and MWCNTs had the highest sensitivity to nucleic acids. Other interesting result is the fact that we were able to distinguish signals for all bases using this electrode.

Reliable Refuge: Two Sky Island Scorpion Species Select Larger, Thermally Stable Retreat Sites.

Science.gov (United States)

Becker, Jamie E; Brown, Christopher A

2016-01-01

Sky island scorpions shelter under rocks and other surface debris, but, as with other scorpions, it is unclear whether these species select retreat sites randomly. Furthermore, little is known about the thermal preferences of scorpions, and no research has been done to identify whether reproductive condition might influence retreat site selection. The objectives were to (1) identify physical or thermal characteristics for retreat sites occupied by two sky island scorpions (Vaejovis cashi Graham 2007 and V. electrum Hughes 2011) and those not occupied; (2) determine whether retreat site selection differs between the two study species; and (3) identify whether thermal selection differs between species and between gravid and non-gravid females of the same species. Within each scorpion's habitat, maximum dimensions of rocks along a transect line were measured and compared to occupied rocks to determine whether retreat site selection occurred randomly. Temperature loggers were placed under a subset of occupied and unoccupied rocks for 48 hours to compare the thermal characteristics of these rocks. Thermal gradient trials were conducted before parturition and after dispersal of young in order to identify whether gravidity influences thermal preference. Vaejovis cashi and V. electrum both selected larger retreat sites that had more stable thermal profiles. Neither species appeared to have thermal preferences influenced by reproductive condition. However, while thermal selection did not differ among non-gravid individuals, gravid V. electrum selected warmer temperatures than its gravid congener. Sky island scorpions appear to select large retreat sites to maintain thermal stability, although biotic factors (e.g., competition) could also be involved in this choice. Future studies should focus on identifying the various biotic or abiotic factors that could influence retreat site selection in scorpions, as well as determining whether reproductive condition affects thermal

River piracy and drainage basin reorganization led by climate-driven glacier retreat

Science.gov (United States)

Shugar, Daniel H.; Clague, John J.; Best, James L.; Schoof, Christian; Willis, Michael J.; Copland, Luke; Roe, Gerard H.

2017-04-01

River piracy--the diversion of the headwaters of one stream into another one--can dramatically change the routing of water and sediment, with a profound effect on landscape evolution. Stream piracy has been investigated in glacial environments, but so far it has mainly been studied over Quaternary or longer timescales. Here we document how retreat of Kaskawulsh Glacier--one of Canada's largest glaciers--abruptly and radically altered the regional drainage pattern in spring 2016. We use a combination of hydrological measurements and drone-generated digital elevation models to show that in late May 2016, meltwater from the glacier was re-routed from discharge in a northward direction into the Bering Sea, to southward into the Pacific Ocean. Based on satellite image analysis and a signal-to-noise ratio as a metric of glacier retreat, we conclude that this instance of river piracy was due to post-industrial climate change. Rapid regional drainage reorganizations of this type can have profound downstream impacts on ecosystems, sediment and carbon budgets, and downstream communities that rely on a stable and sustained discharge. We suggest that the planforms of Slims and Kaskawulsh rivers will adjust in response to altered flows, and the future Kaskawulsh watershed will extend into the now-abandoned headwaters of Slims River and eventually capture the Kluane Lake drainage.

Scientific retreats with 'speed dating': networking to stimulate new interdisciplinary translational research collaborations and team science.

Science.gov (United States)

Ranwala, Damayanthi; Alberg, Anthony J; Brady, Kathleen T; Obeid, Jihad S; Davis, Randal; Halushka, Perry V

2017-02-01

To stimulate the formation of new interdisciplinary translational research teams and innovative pilot projects, the South Carolina Clinical and Translational Research (SCTR) Institute (South Carolina Clinical and Translational Science Award, CTSA) initiated biannual scientific retreats with 'speed dating' networking sessions. Retreat themes were prioritized based on the following criteria; cross-cutting topic, unmet medical need, generation of novel technologies and methodologies. Each retreat begins with an external keynote speaker followed by a series of brief research presentations by local researchers focused on the retreat theme, articulating potential areas for new collaborations. After each session of presentations, there is a 30 min scientific 'speed dating' period during which the presenters meet with interested attendees to exchange ideas and discuss collaborations. Retreat attendees are eligible to compete for pilot project funds on the topic of the retreat theme. The 10 retreats held have had a total of 1004 participants, resulted in 61 pilot projects with new interdisciplinary teams, and 14 funded projects. The retreat format has been a successful mechanism to stimulate novel interdisciplinary research teams and innovative translational research projects. Future retreats will continue to target topics of cross-cutting importance to biomedical and public health research. Copyright © 2016 American Federation for Medical Research.

Little Ice Age advance and retreat of Glaciar Jorge Montt, Chilean Patagonia

Directory of Open Access Journals (Sweden)

A. Rivera

2012-03-01

Full Text Available Glaciar Jorge Montt (48°20' S/73°30' W, one of the main tidewater glaciers of the Southern Patagonian Icefield (SPI, has experienced the greatest terminal retreat observed in Patagonia during the past century, with a recession of 19.5 km between 1898 and 2011. This retreat has revealed trees laying subglacially until 2003. These trees were dated using radiocarbon, yielding burial ages between 460 and 250 cal yrs BP. The presence of old growth forest during those dates indicates that Glaciar Jorge Montt was upvalley of its present position before the commonly recognized Little Ice Age (LIA period in Patagonia. The post-LIA retreat was most likely triggered by climatically induced changes during the 20th century; however, Glaciar Jorge Montt has responded more dramatically than its neighbours. The retreat of Jorge Montt opened a 19.5 km long fjord since 1898, which reaches depths in excess of 390 m. The bathymetry is well correlated with glacier retreat rates, suggesting that dynamic responses of the glacier are at least partially connected to near buoyancy conditions at the ice front, resulting in high calving fluxes, accelerating thinning rates and rapid ice velocities.

In situ synthesis carbonated hydroxyapatite layers on enamel slices with acidic amino acids by a novel two-step method.

Science.gov (United States)

Wu, Xiaoguang; Zhao, Xu; Li, Yi; Yang, Tao; Yan, Xiujuan; Wang, Ke

2015-09-01

In situ fabrication of carbonated hydroxyapatite (CHA) remineralization layer on an enamel slice was completed in a novel, biomimetic two-step method. First, a CaCO3 layer was synthesized on the surface of demineralized enamel using an acidic amino acid (aspartic acid or glutamate acid) as a soft template. Second, at the same concentration of the acidic amino acid, rod-like carbonated hydroxyapatite was produced with the CaCO3 layer as a sacrificial template and a reactant. The morphology, crystallinity and other physicochemical properties of the crystals were characterized using field emission scanning electron microscopy (FESEM), Fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD) and energy-dispersive X-ray analysis (EDAX), respectively. Acidic amino acid could promote the uniform deposition of hydroxyapatite with rod-like crystals via absorption of phosphate and carbonate ions from the reaction solution. Moreover, compared with hydroxyapatite crystals coated on the enamel when synthesized by a one-step method, the CaCO3 coating that was synthesized in the first step acted as an active bridge layer and sacrificial template. It played a vital role in orienting the artificial coating layer through the template effect. The results show that the rod-like carbonated hydroxyapatite crystals grow into bundles, which are similar in size and appearance to prisms in human enamel, when using the two-step method with either aspartic acid or acidic glutamate (20.00 mmol/L). Copyright © 2015 Elsevier B.V. All rights reserved.

Sustainable carbon sources for microbial organic acid production with filamentous fungi.

Science.gov (United States)

Dörsam, Stefan; Fesseler, Jana; Gorte, Olga; Hahn, Thomas; Zibek, Susanne; Syldatk, Christoph; Ochsenreither, Katrin

2017-01-01

The organic acid producer Aspergillus oryzae and Rhizopus delemar are able to convert several alternative carbon sources to malic and fumaric acid. Thus, carbohydrate hydrolysates from lignocellulose separation are likely suitable as substrate for organic acid production with these fungi. Before lignocellulose hydrolysate fractions were tested as substrates, experiments with several mono- and disaccharides, possibly present in pretreated biomass, were conducted for their suitability for malic acid production with A. oryzae. This includes levoglucosan, glucose, galactose, mannose, arabinose, xylose, ribose, and cellobiose as well as cheap and easy available sugars, e.g., fructose and maltose. A. oryzae is able to convert every sugar investigated to malate, albeit with different yields. Based on the promising results from the pure sugar conversion experiments, fractions of the organosolv process from beechwood ( Fagus sylvatica ) and Miscanthus giganteus were further analyzed as carbon source for cultivation and fermentation with A. oryzae for malic acid and R. delemar for fumaric acid production. The highest malic acid concentration of 37.9 ± 2.6 g/L could be reached using beechwood cellulose fraction as carbon source in bioreactor fermentation with A. oryzae and 16.2 ± 0.2 g/L fumaric acid with R. delemar . We showed in this study that the range of convertible sugars for A. oryzae is even higher than known before. We approved the suitability of fiber/cellulose hydrolysate obtained from the organosolv process as carbon source for A. oryzae in shake flasks as well as in a small-scale bioreactor. The more challenging hemicellulose fraction of F. sylvatica was also positively evaluated for malic acid production with A. oryzae .

Scientific Retreats with ‘Speed Dating’: Networking to Stimulate New Interdisciplinary Translational Research Collaborations and Team Science

Science.gov (United States)

Alberg, Anthony J.; Brady, Kathleen T.; Obeid, Jihad S.; Davis, Randal; Halushka, Perry V.

2016-01-01

To stimulate the formation of new interdisciplinary translational research teams and innovative pilot projects, the South Carolina Clinical & Translational Research (SCTR) Institute (South Carolina Clinical and Translational Science Award, CTSA) initiated biannual scientific retreats with “speed dating” networking sessions. Retreat themes were prioritized based on the following criteria; cross-cutting topic, unmet medical need, generation of novel technologies and methodologies. Each retreat commences with an external keynote speaker followed by a series of brief research presentations by local researchers focused on the retreat theme, articulating potential areas for new collaborations. After each session of presentations, there is a 30 minute scientific “speed dating” period during which the presenters meet with interested attendees to exchange ideas and discuss collaborations. Retreat attendees are eligible to compete for pilot project funds on the topic of the retreat theme. The 10 retreats held have had a total of 1004 participants, resulted in 61 pilot projects with new interdisciplinary teams, and 14 funded projects. The retreat format has been a successful mechanism to stimulate novel interdisciplinary research teams and innovative translational research projects. Future retreats will continue to target topics of cross-cutting importance to biomedical and public health research. PMID:27807146

Effect of amino acid-functionalized multi-walled carbon nanotubes ...

Indian Academy of Sciences (India)

In a single-step, rapid microwave-assisted process, multi-walled carbon nanotubes were functionalized by -valine amino acid. Formation of amino acid on nanotube surface was confirmed by Fourier transform-infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, field emission scanning and transmission ...

Retreatment of Exudative Age-Related Macular Degeneration after Loading 3-Monthly Intravitreal Ranibizumab.

Science.gov (United States)

Sugiyama, Atsushi; Sakurada, Yoichi; Honda, Shigeru; Miki, Akiko; Matsumiya, Wataru; Yoneyama, Seigo; Kikushima, Wataru; Iijima, Hiroyuki

2018-01-01

The aim of this study was to investigate the clinical implications of required retreatment after 3-monthly intravitreal ranibizumab (IVR) injections followed by as-needed reinjections up to 5 years in eyes with exudative age-related macular degeneration (AMD). A retrospective cohort study was conducted for 165 treatment-naïve eyes from 165 patients with exudative AMD. Visual changes were investigated in terms of the required retreatments. Retreatment-free proportions were 37.0, 23.7, 16.6, 12.1, and 10.5% at 12, 24, 36, 48, and 60 months, respectively. Visual changes were significantly better in eyes which did not require retreatment at every yearly checkpoint within the 5 years. A multivariate logistic regression analysis revealed that requirement of additional IVR treatments in the first 12-24 months was associated with the T allele (risk allele) of ARMS2 A69S (p = 0.010 and 0.015, respectively). Cox regression analysis revealed that older age (p = 0.046) and the T allele of ARMS2 A69S (p = 0.036) were associated with required retreatment within the 5-year follow-up period. Age and the T allele of ARMS2 A69S are the risk factors requiring retreatments, leading to poor visual change in eyes with exudative AMD following the initial 3-monthly IVR. © 2017 S. Karger AG, Basel.

Activated carbon from peach stones using phosphoric acid activation at medium temperatures.

Science.gov (United States)

Kim, Dong-Su

2004-01-01

In the present study, the activation features of phosphoric acid have been investigated using waste peach stones as the raw material in the production of granular activated carbon. Thermogravimetry/differential thermal analysis was conducted to characterize the thermal behavior of peach stone and titration method was used to evaluate the adsorption capacity of the produced activated carbon. It was observed that the iodine value of the activated carbon increased with activation temperature. However, temperatures higher than 500 degrees C caused a thermal destruction, which resulted in the decrease of the adsorption capacity. Activation longer than 1.5 h at 500 degrees C resulted in thermal degradation of the porous structure of the activated carbon. The adsorption capacity was enhanced with increasing of amounts of phosphoric acid, however, excessive phosphoric acid caused a decrease in the iodine value. In addition, it was found that the carbon yields generally decreased with activation temperature and activation time. Scanning electron microscopy analysis was conducted to observe the changes in the poros structure of the activated carbon produced in different temperatures. Activation of carbon by phosphoric acid was found to be superior to that by CaCl2 and gas activation. The activated carbon produced from peach stone was applied as an adsorbent in the treatment of synthesized wastewater containing cadmium ion and its adsorption capacity was found to be as good as that of the commercial one.

Systematically controlled pore system of ordered mesoporous carbons using phosphoric acid as the in situ generated catalysts for carbonization and activation

Energy Technology Data Exchange (ETDEWEB)

Jin, Xing; Lee, Chang Hyun; Kim, Jin Hoe; You, Dae Jong; Shon, Jeong Kuk; Kim, Ji Man [Dept. of Chemistry, Sungkyunkwan University, Suwon (Korea, Republic of); Pak, Chan Ho [Fuel Cell Group, Corporate R and D Center, Samsung SDI Co. Ltd., Yongin (Korea, Republic of)

2015-08-15

We report on a facile synthesis of the ordered mesoporous carbon (OMC) materials with systematically controlled microporosity and mesoporosity simultaneously through the nano-replication route using phosphoric acid as the acid catalyst and activation agent. The use of phosphoric acid affects the pore structures of OMC materials, such as the formation of numerous micropores by activation of the carbon framework and the enlargement of mesopores by spontaneous phase separation during the carbonization. The mesopore sizes, surface areas, total pore volumes, and micropore volumes of the OMC materials are highly dependent on the phosphoric acid content and can be systematically controlled in the range 3.7–7.5 nm, 1027–2782 m{sup 2} g{sup -1}, 1.12–3.53 cm{sup 3} g{sup -1} and 0.34–0.95 cm{sup 3} g{sup -1}, respectively. OMC materials with systematically controlled pore structures were successfully synthesized using phosphoric acid as the carbonization catalyst and mesoporous silica materials with cubic Ia3d and 2-D hexagonal mesostructures as the templates. The phosphoric acid in the synthesis of ordered mesoporous carbon materials acts as the chemical activating agent for micropore generation of the carbon framework and pore-expanding agent for controlling of mesopore size, in addition to functioning as the acid catalyst. The present synthesis pathway is very useful for preparing OMC materials with tunable mesopore sizes and well-developed microporosities at the same time.

Carbon dioxide therapy and hyaluronic acid for cosmetic correction of the nasolabial folds.

Science.gov (United States)

Nisi, Giuseppe; Cuomo, Roberto; Brandi, Cesare; Grimaldi, Luca; Sisti, Andrea; D'Aniello, Carlo

2016-06-01

The main application of hyaluronic acid filling, in esthetic medicine, is the augmentation of soft tissues. The carbon dioxide therapy, instead, improves quality and elasticity of the dermis and increases the oxygen release to the tissue through an enhancing of the Bohr's effect. The aim of the study was to compare the efficacy, tolerability, and effect duration of hyaluronic acid fillers and the use of carbon dioxide therapy plus hyaluronic acid in the cosmetic correction of nasolabial folds. Forty healthy female patients received a blinded and randomized treatment on nasolabial folds (hyaluronic acid in group A and hyaluronic acid plus subcutaneous injections of carbon dioxide in group B) for cosmetic correction of the nasolabial folds. The results were evaluated by two blinded plastic surgeons after the implant (1 week, 4 and 6 months) using a 1-5 graduated scale (GAIS), and at the same time, each patient was asked to express her opinion about the cosmetic result. Any long-term adverse reaction was reported. The blinded evaluation at 4 and 6 months from the implant shows in all patients a maintenance of a good cosmetic result higher for the side treated with carbon dioxide therapy plus hyaluronic acid. At the control visit, 6 months after the treatment, the patients treated with hyaluronic acid plus carbon dioxide therapy maintain a satisfactory esthetic result while the nasolabial fold treated only with hyaluronic acid shows, in almost all patients, a come back to pretreatment appearance. © 2016 Wiley Periodicals, Inc.

An Examination of the Carbon Isotope Effects Associated with Amino Acid Biosynthesis

Science.gov (United States)

Scott, James H.; O'Brien, Diane M.; Emerson, David; Sun, Henry; McDonald, Gene D.; Salgado, Antonio; Fogel, Marilyn L.

2006-12-01

Stable carbon isotope ratios (δ13C) were determined for alanine, proline, phenylalanine, valine, leucine, isoleucine, aspartate (aspartic acid and asparagine), glutamate (glutamic acid and glutamine), lysine, serine, glycine, and threonine from metabolically diverse microorganisms. The microorganisms examined included fermenting bacteria, organotrophic, chemolithotrophic, phototrophic, methylotrophic, methanogenic, acetogenic, acetotrophic, and naturally occurring cryptoendolithic communities from the Dry Valleys of Antarctica. Here we demonstrated that reactions involved in amino acid biosynthesis can be used to distinguish amino acids formed by life from those formed by nonbiological processes. The unique patterns of δ13C imprinted by life on amino acids produced a biological bias. We also showed that, by applying discriminant function analysis to the δ13C value of a pool of amino acids formed by biological activity, it was possible to identify key aspects of intermediary carbon metabolism in the microbial world. In fact, microorganisms examined in this study could be placed within one of three metabolic groups: (1) heterotrophs that grow by oxidizing compounds containing three or more carbon-to-carbon bonds (fermenters and organotrophs), (2) autotrophs that grow by taking up carbon dioxide (chemolitotrophs and phototrophs), and (3) acetoclastic microbes that grow by assimilation of formaldehyde or acetate (methylotrophs, methanogens, acetogens, and acetotrophs). Furthermore, we demonstrated that cryptoendolithic communities from Antarctica grouped most closely with the autotrophs, which indicates that the dominant metabolic pathways in these communities are likely those utilized for CO2 fixation. We propose that this technique can be used to determine the dominant metabolic types in a community and reveal the overall flow of carbon in a complex ecosystem.

Carbon dioxide sequestration by direct mineral carbonation with carbonic acid

Energy Technology Data Exchange (ETDEWEB)

O' Connor, William K.; Dahlin, David C.; Nilsen, David N.; Walters, Richard P.; Turner, Paul C.

2000-01-01

The Albany Research Center (ARC) of the U.S. Dept. of Energy (DOE) has been conducting a series of mineral carbonation tests at its Albany, Oregon, facility over the past 2 years as part of a Mineral Carbonation Study Program within the DOE. Other participants in this Program include the Los Alamos National Laboratory, Arizona State University, Science Applications International Corporation, and the DOE National Energy Technology Laboratory. The ARC tests have focused on ex-situ mineral carbonation in an aqueous system. The process developed at ARC utilizes a slurry of water mixed with a magnesium silicate mineral, olivine [forsterite end member (Mg2SiO4)], or serpentine [Mg3Si2O5(OH)4]. This slurry is reacted with supercritical carbon dioxide (CO2) to produce magnesite (MgCO3). The CO2 is dissolved in water to form carbonic acid (H2CO3), which dissociates to H+ and HCO3 -. The H+ reacts with the mineral, liberating Mg2+ cations which react with the bicarbonate to form the solid carbonate. The process is designed to simulate the natural serpentinization reaction of ultramafic minerals, and for this reason, these results may also be applicable to in-situ geological sequestration regimes. Results of the baseline tests, conducted on ground products of the natural minerals, have been encouraging. Tests conducted at ambient temperature (22 C) and subcritical CO2 pressures (below 73 atm) resulted in very slow conversion to the carbonate. However, when elevated temperatures and pressures are utilized, coupled with continuous stirring of the slurry and gas dispersion within the water column, significant reaction occurs within much shorter reaction times. Extent of reaction, as measured by the stoichiometric conversion of the silicate mineral (olivine) to the carbonate, is roughly 90% within 24 hours, using distilled water, and a reaction temperature of 185?C and a partial pressure of CO2 (PCO2) of 115 atm. Recent tests using a bicarbonate solution, under identical reaction

Carbon dioxide sequestration by direct mineral carbonation with carbonic acid

Energy Technology Data Exchange (ETDEWEB)

O' Connor, W.K.; Dahlin, D.C.; Nilsen, D.N.; Walters, R.P.; Turner, P.C.

2000-07-01

The Albany Research Center (ARC) of the US Department of Energy (DOE) has been conducting a series of mineral carbonation tests at its Albany, Oregon, facility over the past 2 years as part of a Mineral Carbonation Study Program within the DOE. The ARC tests have focused on ex-situ mineral carbonation in an aqueous system. The process developed at ARC utilizes a slurry of water mixed with a magnesium silicate mineral, olivine [forsterite and member (mg{sub 2}SiO{sub 4})], or serpentine [Mg{sub 3}Si{sub 2}O{sub 5}(OH){sub 4}]. This slurry is reacted with supercritical carbon dioxide (CO{sub 2}) to produce magnesite (MgCO{sub 3}). The CO{sub 2} is dissolved in water to form carbonic acid (H{sub 2}CO{sub 3}), which dissociates to H{sup +} and HCO{sub 3}{sup {minus}}. The H{sup +} reacts with the mineral, liberating Mg{sup 2+} cations which react with the bicarbonate to form the solid carbonate. The process is designed to simulate the natural serpentinization reaction of ultramafic minerals, and for this reason, these results may also be applicable to in-situ geological sequestration regimes. Results of the baseline tests, conducted on ground products of the natural minerals, have been encouraging. Tests conducted at ambient temperature (22 C) and subcritical CO{sub 2} pressures (below 73 atm) resulted in very slow conversion to the carbonate. However, when elevated temperatures and pressures are utilized, coupled with continuous stirring of the slurry and gas dispersion within the water column, significant reaction occurs within much shorter reaction times. Extent of reaction, as measured by the stoichiometric conversion of the silicate mineral (olivine) to the carbonate, is roughly 90% within 24 hours, using distilled water, and a reaction temperature of 185 C and a partial pressure of CO{sub 2} (P{sub CO{sub 2}}) of 115 atm. Recent tests using a bicarbonate solution, under identical reaction conditions, have achieved roughly 83% conversion of heat treated serpentine

Predicting sorption of organic acids to a wide range of carbonized sorbents

Science.gov (United States)

Sigmund, Gabriel; Kah, Melanie; Sun, Huichao; Hofmann, Thilo

2016-04-01

Many contaminants and infochemicals are organic acids that undergo dissociation under environmental conditions. The sorption of dissociated anions to biochar and other carbonized sorbents is typically lower than that of neutral species. It is driven by complex processes that are not yet fully understood. It is known that predictive approaches developed for neutral compounds are unlikely to be suitable for organic acids, due to the effects of dissociation on sorption. Previous studies on the sorption of organic acids to soils have demonstrated that log Dow, which describes the decrease in hydrophobicity of acids upon dissociation, is a useful alternative to log Kow. The aim of the present study was to adapt a log Dow based approach to describe the sorption of organic acids to carbonized sorbents. Batch experiments were performed with a series of 9 sorbents (i.e., carbonized wood shavings, pig manure, and sewage sludge, carbon nanotubes and activated carbon), and four acids commonly used for pesticidal and biocidal purposes (i.e., 2,4-D, MCPA, 2,4-DB, and triclosan). Sorbents were comprehensively characterized, including by N2 and CO2 physisorption, Fourier transform infrared spectroscopy, and elemental analysis. The wide range of sorbents considered allows (i) discussing the mechanisms driving the sorption of neutral and anionic species to biochar, and (ii) their dependency on sorbate and sorbent properties. Results showed that the sorption of the four acids was influenced by factors that are usually not considered for neutral compounds (i.e., pH, ionic strength). Dissociation affected the sorption of the four compounds, and sorption of the anions ranged over five orders of magnitude, thus substantially contributing to sorption in some cases. For prediction purposes, most of the variation in sorption to carbonized sorbents (89%) could be well described with a two-parameter regression equation including log Dow and sorbent specific surface area. The proposed model

Development of poly(aspartic acid-co-malic acid) composites for calcium carbonate and sulphate scale inhibition.

Science.gov (United States)

Mithil Kumar, N; Gupta, Sanjay Kumar; Jagadeesh, Dani; Kanny, K; Bux, F

2015-01-01

Polyaspartic acid (PSI) is suitable for the inhibition of inorganic scale deposition. To enhance its scale inhibition efficiency, PSI was modified by reacting aspartic acid with malic acid (MA) using thermal polycondensation polymerization. This reaction resulted in poly(aspartic acid-co-malic acid) (PSI-co-MA) dual polymer. The structural, chemical and thermal properties of the dual polymers were analysed by using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry and gel permeation chromatography. The effectiveness of six different molar ratios of PSI-co-MA dual polymer for calcium carbonate and calcium sulphate scale inhibition at laboratory scale batch experiments was evaluated with synthetic brine solution at selected doses of polymer at 65-70°C by the static scale test method. The performance of PSI-co-MA dual polymer for the inhibition of calcium carbonate and calcium sulphate precipitation was compared with that of a PSI single polymer. The PSI-co-MA exhibited excellent ability to control inorganic minerals, with approximately 85.36% calcium carbonate inhibition and 100% calcium sulphate inhibition at a level of 10 mg/L PSI-co-MA, respectively. Therefore, it may be reasonably concluded that PSI-co-MA is a highly effective scale inhibitor for cooling water treatment applications.

Surface treated carbon catalysts produced from waste tires for fatty acids to biofuel conversion

Science.gov (United States)

Hood, Zachary D.; Adhikari, Shiba P.; Wright, Marcus W.; Lachgar, Abdessadek; Li, Yunchao; Naskar, Amit K.; Paranthaman, Mariappan Parans

2018-02-06

A method of making solid acid catalysts includes the step of sulfonating waste tire pieces in a first sulfonation step. The sulfonated waste tire pieces are pyrolyzed to produce carbon composite pieces having a pore size less than 10 nm. The carbon composite pieces are then ground to produce carbon composite powders having a size less than 50 .mu.m. The carbon composite particles are sulfonated in a second sulfonation step to produce sulfonated solid acid catalysts. A method of making biofuels and solid acid catalysts are also disclosed.

A century of ice retreat on Kilimanjaro: the mapping reloaded

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N. J. Cullen

2013-03-01

Full Text Available A new and consistent time series of glacier retreat on Kilimanjaro over the last century has been established by re-interpreting two historical maps and processing nine satellite images, which removes uncertainty about the location and extent of past and present ice bodies. Three-dimensional visualization techniques were used in conjunction with aerial and ground-based photography to facilitate the interpretation of ice boundaries over eight epochs between 1912 and 2011. The glaciers have retreated from their former extent of 11.40 km2 in 1912 to 1.76 km2 in 2011, which represents a total loss of about 85% of the ice cover over the last 100 yr. The total loss of ice cover is in broad agreement with previous estimates, but to further characterize the spatial and temporal variability of glacier retreat a cluster analysis using topographical information (elevation, slope and aspect was performed to segment the ice cover as observed in 1912, which resulted in three glacier zones being identified. Linear extrapolation of the retreat in each of the three identified glacier assemblages implies the ice cover on the western slopes of Kilimanjaro will be gone before 2020, while the remaining ice bodies on the plateau and southern slopes will most likely disappear by 2040. It is highly unlikely that any body of ice will be present on Kilimanjaro after 2060 if present-day climatological conditions are maintained. Importantly, the geo-statistical approach developed in this study provides us with an additional tool to characterize the physical processes governing glacier retreat on Kilimanjaro. It remains clear that, to use glacier response to unravel past climatic conditions on Kilimanjaro, the transition from growth to decay of the plateau glaciers must be further resolved, in particular the mechanisms responsible for vertical cliff development.

Continuing evidence for poorer treatment outcomes for single male patients: Retreatment data from RTOG 97-14

International Nuclear Information System (INIS)

Konski, Andre; DeSilvio, Michelle; Hartsell, William; Watkins-Bruner, Deborah; Coyne, James; Scarantino, Charles; JanJan, Nora

2006-01-01

Purpose: The specific aim of this study was to evaluate outcome differences by gender and partner status for patients treated on Radiation Therapy Oncology Group (RTOG) protocol 97-14. Methods and Materials: RTOG 97-14 randomized patients with metastatic breast or prostate cancer to bone to receive 8 Gy in 1 fraction or 30 Gy in 10 fractions. Retreatment rates and overall survival were made based upon gender, marital status, and Karnofsky Performance Status (KPS). The cumulative incidence method was used to estimate retreatment time at 36 months from enrollment, and Gray's test was used to test for treatment differences within the same groupings. Marital status, gender, KPS, and treatment were variables tested in a univariate Cox model evaluating the time to retreatment. Results: Married men and women and single women receiving 30 Gy had significantly longer time to retreatment, p = 0.0067, p = 0.0052, and p = 0.0009 respectively. We failed to show a difference in retreatment rates over time in single men receiving either 30 Gy or 8 Gy. Univariate analysis of the entire group determined patients receiving 30 Gy in 10 fractions significantly less likely to receive retreatment, p < 0.0001, with a trend toward single patients less likely to be re-treated, p = 0.07. Conclusion: Non-disease-related variables, such as social support, might influence the results of clinical trials with subjective endpoints such as retreatment rates. The statistically nonsignificant difference in the 36-month retreatment rates observed in single male patients receiving 8 Gy may be a result of inadequate social support systems in place to facilitate additional care. Patients receiving 8 Gy in a single fraction had significantly higher retreatment rates compared with patients receiving 30 Gy in 10 fractions

Imprinted zeolite modified carbon paste electrode as a potentiometric sensor for uric acid

Science.gov (United States)

Khasanah, Miratul; Widati, Alfa Akustia; Fitri, Sarita Aulia

2016-03-01

Imprinted zeolite modified carbon paste electrode (carbon paste-IZ) has been developed and applied to determine uric acid by potentiometry. The imprinted zeolite (IZ) was synthesized by the mole ratio of uric acid/Si of 0.0306. The modified electrode was manufactured by mass ratio of carbon, IZ and solid paraffin was 40:25:35. The modified electrode had shown the measurement range of 10-5 M to 10-2 M with Nernst factor of 28.6 mV/decade, the detection limit of 5.86 × 10-6 M and the accuracy of 95.3 - 105.0%. Response time of the electrode for uric acid 10-5 M - 10-2 M was 25 - 44 s. The developed electrode showed the high selectivity toward uric acid in the urea matrix. Life time of the carbon paste-IZ electrode was 10 weeks.

Synthesis of graphitic carbon nitride by reaction of melamine and uric acid

International Nuclear Information System (INIS)

Dante, Roberto C.; Martin-Ramos, Pablo; Correa-Guimaraes, Adriana; Martin-Gil, Jesus

2011-01-01

Highlights: → Graphitic carbon nitrides by CVD of melamine and uric acid on alumina. → The building blocks of carbon nitrides are heptazine nuclei. → Composite particles with alumina core and carbon nitride coating. - Abstract: Graphitic carbon nitrides were synthesized starting from melamine and uric acid. Uric acid was chosen because it thermally decomposes, and reacts with melamine by condensation at temperatures in the range of 400-600 deg. C. The reagents were mixed with alumina and subsequently the samples were treated in an oven under nitrogen flux. Alumina favored the deposition of the graphitic carbon nitrides layers on the exposed surface. This method can be assimilated to an in situ chemical vapor deposition (CVD). Infrared (IR) spectra, as well as X-ray diffraction (XRD) patterns, are in accordance with the formation of a graphitic carbon nitride with a structure based on heptazine blocks. These carbon nitrides exhibit poor crystallinity and a nanometric texture, as shown by transmission electron microscopy (TEM) analysis. The thermal degradation of the graphitic carbon nitride occurs through cyano group formation, and involves the bridging tertiary nitrogen and the bonded carbon, which belongs to the heptazine ring, causing the ring opening and the consequent network destruction as inferred by connecting the IR and X-ray photoelectron spectroscopy (XPS) results. This seems to be an easy and promising route to synthesize graphitic carbon nitrides. Our final material is a composite made of an alumina core covered by carbon nitride layers.

Acidity controls on dissolved organic carbon mobility in organic soils

Czech Academy of Sciences Publication Activity Database

Evans, Ch. D.; Jones, T.; Burden, A.; Ostle, N.; Zielinski, P.; Cooper, M.; Peacock, M.; Clark, J.; Oulehle, Filip; Cooper, D.; Freeman, Ch.

2012-01-01

Roč. 18, č. 11 (2012), s. 3317-3331 ISSN 1354-1013 Institutional support: RVO:67179843 Keywords : acidity * dissolved organic carbon * organic soil * peat * podzol * soil carbon * sulphur Subject RIV: EH - Ecology, Behaviour Impact factor: 6.910, year: 2012

The Role of Silence at the Retreats of a Buddhist Community

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Orsolya Huszár

2016-12-01

Full Text Available The purpose of the study is to establish that the definition of silence as simply an absence of something or as the background of communication proves to be inadequate in a number of communicative instances. The interpretation of silence is culturally determined, and the underappreciation of its role is typical in low-context Western cultures; this is also evinced by the neglect of the topic in the literature. The present study will describe the communicative functions of silence through the findings of field work conducted at the retreats of a Buddhist community in Hungary, providing empirical input for the relevant theoretical constructs. The research findings show that silence is accorded a central role in essentially every component of the retreat (meditations, relaxation, ceremonies, teachings, small-group sharings, meals and rest; and while each event at the retreat focuses primarily on a different specific function of communication, the entire retreat does involve the linkage, affecting, revelational and – to a certain extent – activating functions (to follow the five-element typology of J. Vernon Jensen, as well as – to a lesser extent – the judgmental function. The research also shows that it requires time for individuals in a low-context culture to recognize the “point” of silence – something that the retreats provide the right opportunity for. In fact, the insights the individuals arrived at through these occasions could be put to use in their daily lives, helping their problem-solving and social relationships and in general improving their quality of life.

Transcending Gender: Female Non-Buddhists’ Experiences of the Vipassanā Meditation Retreat

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Brooke Schedneck

2018-03-01

Full Text Available Female non-Buddhists have been writing detailed descriptions of their personal experiences in vipassanā meditation retreats since the 1960s. These memoirists relate to the English-speaking world their experience of the retreat process and self-transformations. Early memoirists traveled Asia in order to learn and practice vipassanā meditation. These memoirs are as much about the meditation practice itself as living in an Asian culture. The mindfulness craze, beginning in the late 2000s, brought with it increased awareness of vipassanā practice. At this time we see a renewed interest in recording vipassanā retreat experiences, but these are even more personal and not concerned with travel, as many vipassanā meditation retreats are now available outside of Asia. I consider four female memoirists: Marie Byles and Jane Hamilton-Smith, writing in the 1960s and 1970s, and Raji Lukkoor, and Jennifer Howd, whose memoirs appeared in 2010 and 2014, respectively. These women’s writings demonstrate that, although non-Buddhist female meditators understand vipassanā meditation as a nongendered practice, it is still an embodied, gendered experience. Each of these women has different reactions to the female gender on the retreat, from outrage at gender discrimination to acceptance of it, from judgment of female teachers and meditators to revealing a more feminine self.

Production of activated carbon from peanut hill using phosphoric acid and microwave activation

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Weerawat Clowutimon

2015-06-01

Full Text Available The optimum conditions for preparing activated carbon from peanut hulls by phosphoric acid and microwave activation were studied. Factors investigated in this study were temperature of carbonization at 300, 350, 400 and 450๐ C, and time of carbonization at 30, 60 and 90 minutes. The optimum yield was observed that carbonization temperature of 400๐ C and time at 60 minutes, respectively. The yield of charcoal was 39% and the f ix carbon was 69%. Then the charcoal was activated by phosphoric acid and microwave irradiation, respectively. The effect of the weight per volume ratios of charcoal to activating acid (1:1, 1:2 and 2:1(W/V, microwave power at (activated 300, 500 and 700 watts, and activated time (30, 60 and 90 seconds were studied. The results showed that the optimum conditions for activating peanut charcoal were 1:2 (W/V charcoal per activating acid, microwave power 700 watts for 90 seconds. The results yielding maximum surface area by BET method was 303.1 m2 /g and pore volume was 0.140 cm3 /g. An efficiency of maximum iodine adsorption was 418 mg iodine/g activated carbon. Comparing the adsorption efficiency of non- irradiated and irradiated activated carbon, the efficiency of irradiated activated carbon improved up to 31%, due to its larger surface area and pore volume.

Highly Efficient Procedure for the Synthesis of Fructone Fragrance Using a Novel Carbon based Acid

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Xuezheng Liang

2010-08-01

Full Text Available The novel carbon based acid has been synthesized via one-step hydrothermal carbonization of furaldehyde and hydroxyethylsulfonic acid. A highly efficient procedure for the synthesis of fructone has been developed using the novel carbon based acid. The results showed that the catalyst possessed high activity for the reaction, giving a yield of over 95%. The advantages of high activity, stability, reusability and low cost for a simple synthesis procedure and wide applicability to various diols and β-keto esters make this novel carbon based acid one of the best choices for the reaction.

Assessment of Apical Extrusion of Debris during Endodontic Retreatment with 3 Rotary Nickel-Titanium Retreatment Systems and Hand Files

Directory of Open Access Journals (Sweden)

Gkampesi S.

2016-03-01

Full Text Available Aim: to evaluate the amount of debris extruded apically as well as the time needed for removal of root canal filling material using ProTaper, MTwo, REndo NiTi rotary retreatment systems and hand files.

Pd(II)/Bipyridine-Catalyzed Conjugate Addition of Arylboronic Acids to α,β-Unsaturated Carboxylic Acids. Synthesis of β-Quaternary Carbons Substituted Carboxylic Acids.

Science.gov (United States)

Liu, Rui; Yang, Zhenyu; Ni, Yuxin; Song, Kaixuan; Shen, Kai; Lin, Shaohui; Pan, Qinmin

2017-08-04

Pd(II)/bipyridine-catalyzed conjugate addition of arylboronic acids to α,β-unsaturated carboxylic acids (including β,β-disubstituted acrylic acids) was developed and optimized, which provided a mild and convenient method for the highly challenging synthesis of β-quaternary carbons substituted carboxylic acids.

Extreme beach retreat history inferred from cut-and-fill beach deposits at Moruya, SE Australia

Science.gov (United States)

Tamura, T.; Woodroffe, C. D.; Oliver, T.; Cunningham, A. C.

2017-12-01

A sequence of beach ridges often records a `cut and fill', where the fair-weather swash accretion of beach sand is punctuated by storm erosion. The detailed chronology of the sequence is thus a clue to decipher past storm events and associated beach erosion, but has not been explored much. Here we explore the potential of such a sequence to detect past extreme retreats in Bengello Beach at Moruya, southeastern Australia. Beach monitoring since 1972 reveals that Bengello beach has shown a typical cut and fill, in which the beach retreats several tens of meters in relation to storms and recovers within a following few years. A storm event caused extreme retreat up to 50 m in 1974. Since then, no retreat exceeded 30 m. The beach monitoring highlights the sporadic nature of the prograded beach deposits; they can only be preserved as stratigraphic records during rapid beach recovery following a large retreat deeper than the beach profile envelope. Thus, ages of the preserved beach deposits roughly correspond to timings of large retreat. Optically-stimulated luminescence (OSL) ages were determined for beach deposits at 5-10 m intervals along a shore-normal transect from the modern foredune to beach ridge 120 m inland. The most landward sample was dated as 510 yr, indicating that the net progradation rate is 0.24 m/yr, concordant with both the long- and short-term rates since the mid Holocene and 1972, respectively. Other ages show four events of retreat around 350, 180, 130 and 90 yr, and also reflect the beach scarp resulting from the 1974 event. The retreat of each event is given by the distance between the shoreline position prior to storm erosion and relevant gap in OSL age. The position of the pre-storm shoreline is estimated by assuming a constant rate of the net progradation of 0.24 m/yr, as with long- and short-term rates. The retreat of the four events is then determined as 45-55 m, similar to the 1974 event. In summary, extreme beach retreats, including that in

Study of the biogenesis of flavones and cinnamic acids by using molecules labelled with carbon 14

International Nuclear Information System (INIS)

Chabannes, Bernard

1970-01-01

This research thesis reports the study of flavones, flavonoid compounds and cinnamic acids which are very common as natural pigments in plant species. The author first reports the study of the synthesis of shikimic acid labelled with carbon 14 (biological methods of preparation, synthesis), and then the synthesis of prunin labelled with carbon 14. The next part reports the study of the transformation of prunin labelled with carbon 14 into cosmosiine in flowers with white cosmos. The author finally compares the introduction of cinnamic acid and of shikimic acid (both labelled with carbon 14) into the sinapic acid of red cabbage leaves

Spiral computed tomography assessment of the efficacy of different rotary versus hand retreatment system

OpenAIRE

Neelam Mittal; Jyoti Jain

2014-01-01

Aims: The purpose of this study was to evaluate the efficacy of nickel-titanium rotary retreatment systems versus stainless steel hand retreatment system with or without solvent for gutta-percha removal during retreatment. Materials and Methods: Sixty extracted human mandibular molar teeth with single canal in a distal root was prepared with ProTaper rotary nickel-titanium files and obturated with gutta-percha and sealer. The teeth were randomly divided into six groups of 10 specimens in ...

Electrochemical oxidation of ascorbic acid mediated by carbon nano tubes/ Li+/ carbon paste modified solid electrode

International Nuclear Information System (INIS)

Goh, J.K.; Tan, W.T.

2008-01-01

Multi-walled carbon nano tube (MWCNT) was used to modify BPPG electrode because of its unique structure and extraordinary properties. MWCNT modified electrode exhibited obvious enhancing and electro catalyzing effects to the oxidation of ascorbic acid using cyclic voltammetry technique. MWCNT was bonded on BPPG electrode surface using carbon paste with ratio of 30 % (w/ W) carbon paste (binder): 70 % (w/ w) MWCNT. This method of modification has lowered the capacitance background current and enabled lower detection limit of ascorbic acid concentration. The electrical conductivity property of MWCNT modified electrode was further improved with the intercalation with lithium ion and resulted in current enhancement of 2 times on the oxidation current of ascorbic acid. Parameters of pH and temperature showed significant relation to the sensitivity of MWCNT modified electrode. Under the optimized parameters, the calibration curve constructed was linear up from 50 μM to 5 mM with sensitivity of 34.5 mA M -1 . The practical application of MWCNT modified electrode was demonstrated with Vitamin C pill and orange juice. Good reproducibility and recovery of ascorbic acid concentration showed the feasibility of MWCNT modified electrode to be used in the detection of ascorbic acid in aqueous solution. This also proposed MWCNT modified BPPG electrode possessed advantages such as low detection limit, high stability, low cost and simplicity in fabrication. (author)

Transformation of acetate carbon into carbohydrate and amino acid metabilites during decomposition in soil

DEFF Research Database (Denmark)

Sørensen, Lasse Holst; Paul, E. A.

1971-01-01

Carbon-14-labelled acetate was added to a heavy clay soil of pH 7.6 to study the transformation of acetate carbon into carbohydrate and amino acid metabolites during decomposition. The acetate was totally metabolized after 6 days of incubation at 25°C when 70% of the labelled carbon had been...... evolved as CO2. Maximum incorporation of trace-C into the various organic fractions was observed after 4 days when 19% of residual, labelled carbon in the soil was located in carbohydrates, 29 % in amino acids and 21 % in the insoluble residue of the soil. The curves showing the amounts of labelled carbon...... days of incubation, 2.2% of the labelled carbon originally added to the soil was located in carbohydrate metabolites, 7% in amino acid metabolites and 5% in the insoluble residue. The carbon in these fractions accounted for 77% of the total, residual, labelled carbon in the soil; 12% in carbohydrates...

Morphology-dependent Electrochemical Enhancements of Porous Carbon as Sensitive Determination Platform for Ascorbic Acid, Dopamine and Uric Acid

Science.gov (United States)

Cheng, Qin; Ji, Liudi; Wu, Kangbing; Zhang, Weikang

2016-02-01

Using starch as the carbon precursor and different-sized ZnO naoparticles as the hard template, a series of porous carbon materials for electrochemical sensing were prepared. Experiments of scanning electron microscopy, transmission electron microscopy and Nitrogen adsorption-desorption isotherms reveal that the particle size of ZnO has big impacts on the porous morphology and surface area of the resulting carbon materials. Through ultrasonic dispersion of porous carbon and subsequent solvent evaporation, different sensing interfaces were constructed on the surface of glassy carbon electrode (GCE). The electrochemical behaviors of ascorbic acid (AA), dopamine (DA) and uric acid (UA) were studied. On the surface of porous carbon materials, the accumulation efficiency and electron transfer ability of AA, DA and UA are improved, and consequently their oxidation signals enhance greatly. Moreover, the interface enhancement effects of porous carbon are also controlled by the particle size of hard template. The constructed porous carbon interface displays strong signal amplification ability and holds great promise in constructing a sensitive platform for the simultaneous determination of AA, DA and UA.

Acidic weathering of carbonate building stones: experimental assessment

Directory of Open Access Journals (Sweden)

Ryszard Kryza

2009-06-01

Full Text Available Three types of carbonate rocks, travertine, limestone and marble have been studied to determine their selected technical parameters (water absorption, resistance to salt crystallization damage and reaction to experimentally modelled acid rain weathering imitating the polluted urban atmospheric conditions. The acidic agents present in natural acid rain precipitation, H2SO4, HCl, HNO3, CH3COOH and mixture of all the acids, “Acid mix”, were tested. The initial stages of acid weathering involve, apart from chemical dissolution, particularly intense physical detachment of rock particles (granular disintegration significantly contributing to the total mass loss. Travertine was found to be most prone to salt crystallization damage and to acid weathering, and these features should be taken into account especially in external architectural usage of this stone in cold climate conditions and polluted urban atmosphere.

Adsorption of perfluoroalkyl acids by carbonaceous adsorbents: Effect of carbon surface chemistry

International Nuclear Information System (INIS)

Zhi, Yue; Liu, Jinxia

2015-01-01

Adsorption by carbonaceous sorbents is among the most feasible processes to remove perfluorooctane sulfonic (PFOS) and carboxylic acids (PFOA) from drinking and ground waters. However, carbon surface chemistry, which has long been recognized essential for dictating performance of such sorbents, has never been considered for PFOS and PFOA adsorption. Thus, the role of surface chemistry was systematically investigated using sorbents with a wide range in precursor material, pore structure, and surface chemistry. Sorbent surface chemistry overwhelmed physical properties in controlling the extent of uptake. The adsorption affinity was positively correlated carbon surface basicity, suggesting that high acid neutralizing or anion exchange capacity was critical for substantial uptake of PFOS and PFOA. Carbon polarity or hydrophobicity had insignificant impact on the extent of adsorption. Synthetic polymer-based Ambersorb and activated carbon fibers were more effective than activated carbon made of natural materials in removing PFOS and PFOA from aqueous solutions. - Highlights: • Adsorption of PFOS and PFOA by ten carbonaceous adsorbents were compared. • Surface chemistry of the adsorbents controlled adsorption affinity. • Carbon surface basicity was positively correlated with the extent of PFOS and PFOA uptake. • Carbon polarity or hydrophobicity was not correlated with adsorption affinity. • Synthetic polymer-based adsorbents were more effective in removing PFOS and PFOA. - Carbon surface basicity is the primary factor that influences adsorption affinity of the carbonaceous sorbents for perfluorooctane sulfonic and carboxylic acids

Evaluation of apically extruded debris during root canal retreatment with two different rotary systems followed by a self-adjusting file.

Science.gov (United States)

Cakici, Fatih; Cakici, Elif B; Küçükekenci, Funda Fundaoglu

2016-02-01

To compare the amount of apically extruded debris during root canal retreatment using ProTaper retreatment system (Dentsply Maillefer, Ballaigues, Switzerland), ProTaper retreatment system with Self-Adjusting File (SAF) system (ReDent-Nova, Ra'anana, Israel), Mtwo retreatment system (VDW, Munich, Germany), Mtwo retreatment system with SAF instruments. In total, 72 extracted human mandibular incisor teeth were used. All root canals were prepared with ProTaper universal (Dentsply Maillefer) up to F2 file and filled with gutta percha and AH plus sealer using cold lateral condensation before being assembled randomly into 4 groups (n = 18 each). Root canal filling materials were removed using the ProTaper retreatment system, the ProTaper retreatment system followed by SAF system, Mtwo retreatment system and Mtwo retreatment system followed by SAF system. Debris extruded apically during the removal of canal filling material was collected into preweighed Eppendorf tubes. The tubes were then stored in an incubator at 70°C for 5 days. The weight of the dry extruded debris was established by subtracting the preretreatment and postretreatment weight of the Eppendorf tubes for each group. The data obtained were analyzed using Kruskal-Wallis test. All retreatment techniques caused the apical extrusion of debris. There was no significant difference between the groups statistically (p>0.05). The results of this study showed that SAF system after Mtwo retreatment system and ProTaper retreatment system for improving retreatment has no significant effect on the amount of debris extruded apically.

Safety of BTZ retreatment for patients with low-grade peripheral neuropathy during the initial treatment.

Science.gov (United States)

Vidisheva, Aleksandra P; Wang, James; Spektor, Tanya M; Bitran, Jacob D; Lutzky, Jose; Tabbara, Imad A; Ye, Joseph Z; Ailawadhi, Sikander; Stampleman, Laura V; Steis, Ronald G; Moezi, Mehdi M; Swift, Regina A; Maluso, Tina M; Udd, Kyle A; Eshaghian, Shahrooz; Nassir, Youram; Berenson, James R

2017-10-01

Neuropathy is an important complication that may limit treatment options for patients with multiple myeloma. Previous studies have focused on treatment efficacy and have shown that retreatment with bortezomib (BTZ) is an effective treatment option. The goal of this study was to focus on the clinical manifestations of peripheral neuropathy (PN) and to retrospectively compare the incidence and severity of PN between the initial BTZ regimen and upon retreatment. Furthermore, this study evaluated how certain factors affect BIPN, which will help determine what conditions should be considered prior to retreatment. Charts were reviewed from 93 patients who were retreated with a BTZ-containing regimen after previously being treated with this drug. Among the patients who developed PN, most patients in the study had low-grade neuropathy during the initial BTZ treatment (n = 52, 68%). The results showed no evidence of cumulative toxicity, and there was no significant difference in the incidence and severity of PN upon retreatment. Factors such as the presence of baseline PN, number of prior treatments, dose of BTZ, and comorbidities did not increase the severity of PN upon retreatment. The lapse of time between the two regimens also did not affect the severity of PN. The results suggest that retreatment with BTZ may be a feasible option, without additional risks of PN, for MM patients even with peripheral neuropathy during their initial treatment with this drug.

Contrasting evidence of Holocene ice margin retreat, south-western Greenland

DEFF Research Database (Denmark)

Levy, L. B.; Larsen, N. K.; Davidson, T. A.

2017-01-01

Constraining the Greenland Ice Sheet's (GrIS) response to Holocene climate change provides calibrations for ice sheet models that hindcast past ice margin fluctuations. Ice sheet models predict enhanced ice retreat in south-western Greenland during the middle Holocene; however, few geological...... observations corroborating the extensive retreat are available. We present new data from lake sediment cores from the Isua region, south-western Greenland, which provide constraints on Holocene fluctuations of the GrIS margins. Our data indicate that the main GrIS margin was 30 km west of its present...

Fumaric acid: an overlooked form of fixed carbon in Arabidopsis and other plant species

International Nuclear Information System (INIS)

Chia, D.W.; Yoder, T.J.; Reiter, W.D.; Gibson, S.I.

2000-01-01

Photoassimilates are used by plants for production of energy, as carbon skeletons and in transport of fixed carbon between different plant organs. Many studies have been devoted to characterizing the factors that. regulate photoassimilate concentrations in different plant species. Most studies examining photoassimilate concentrations in C(sub 3) plants have focused on analyzing starch and soluble sugars. However, work presented here demonstrates that a number of C(sub 3) plants, including the popular model organism Arabidopsis thaliana (L.) Heynh., and agriculturally important plants, such as soybean[Glycine ma (L.) Merr.], contain significant quantities of furnaric acid. In fact, furnaric acid can accumulate to levels of several mg per g fresh weight in A-abidopsis leaves, often exceeding starch and soluble sugar levels. Furnaric acid is a component of the tricarboxylic acid cycle and, like starch and soluble sugars, can be metabolized to yield energy and carbon skeletons for production of other compounds. Fumaric acid concentrations increase with plant age and light intensity in Arabidopsis leaves. Arabidopsis phloem exudates contain significant quantities of fumaric acid, raising the possibility that fumaric acid may function in carbon transport

Fumaric acid: an overlooked form of fixed carbon in Arabidopsis and other plant species

Energy Technology Data Exchange (ETDEWEB)

Chia, D.W.; Yoder, T.J.; Reiter, W.D.; Gibson, S.I.

2000-10-01

Photoassimilates are used by plants for production of energy, as carbon skeletons and in transport of fixed carbon between different plant organs. Many studies have been devoted to characterizing the factors that. regulate photoassimilate concentrations in different plant species. Most studies examining photoassimilate concentrations in C{sub 3} plants have focused on analyzing starch and soluble sugars. However, work presented here demonstrates that a number of C{sub 3} plants, including the popular model organism Arabidopsis thaliana (L.) Heynh., and agriculturally important plants, such as soybean [Glycine ma (L.) Merr.], contain significant quantities of furnaric acid. In fact, furnaric acid can accumulate to levels of several mg per g fresh weight in A-abidopsis leaves, often exceeding starch and soluble sugar levels. Furnaric acid is a component of the tricarboxylic acid cycle and, like starch and soluble sugars, can be metabolized to yield energy and carbon skeletons for production of other compounds. Fumaric acid concentrations increase with plant age and light intensity in Arabidopsis leaves. Arabidopsis phloem exudates contain significant quantities of fumaric acid, raising the possibility that fumaric acid may function in carbon transport.

Measuring Surface Deformation in Glacier Retreated Areas Based on Ps-Insar - Geladandong Glacier as a Case Study

Science.gov (United States)

Mohamadi, B.; Balz, T.

2018-04-01

Glaciers are retreating in many parts of the world as a result of global warming. Many researchers consider Qinghai-Tibetan Plateau as a reference for climate change by measuring glaciers retreat on the plateau. This retreat resulted in some topographic changes in retreated areas, and in some cases can lead to geohazards as landslides, and rock avalanches, which is known in glacier retreated areas as paraglacial slope failure (PSF). In this study, Geladandong biggest and main glacier mass was selected to estimate surface deformation on its glacier retreated areas and define potential future PSF based on PS-InSAR technique. 56 ascending and 49 descending images were used to fulfill this aim. Geladandong glacier retreated areas were defined based on the maximum extent of the glacier in the little ice age. Results revealed a general uplift in the glacier retreated areas with velocity less than 5mm/year. Obvious surface motion was revealed in seven parts surround glacier retreated areas with high relative velocity reached ±60mm/year in some parts. Four parts were considered as PSF potential motion, and two of them showed potential damage for the main road in the study area in case of rock avalanche into recent glacier lakes that could result in glacier lake outburst flooding heading directly to the road. Finally, further analysis and field investigations are needed to define the main reasons for different types of deformation and estimate future risks of these types of surface motion in the Qinghai-Tibetan Plateau.

Corrosion by concentrated sulfuric acid in carbon steel pipes and tanks: state of the art

Energy Technology Data Exchange (ETDEWEB)

Panossian, Zehbour; Almeida, Neusvaldo Lira de; Sousa, Raquel Maria Ferreira de [Instituto de Pesquisas Tecnologicas (IPT), Sao Paulo, SP (Brazil); Pimenta, Gutemberg de Souza [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil). Centro de Pesquisas e Desenvolvimento (CENPES); Marques, Leandro Bordalo Schmidt [PETROBRAS Engenharia, Rio de Janeiro, RJ (Brazil)

2009-07-01

PETROBRAS, allied to the policy of reduction of emission of pollutants, has been adjusting the processes of the new refineries to obtain products with lower sulfur content. Thus, the sulfur dioxide, extracted from the process gases of a new refinery to be built in the Northeast, will be used to produce sulfuric acid with concentration between (94-96) %. This acid will be stored in carbon steel tanks and transported through a buried 8-km carbon steel pipe from the refinery to a pier, where it will be loaded onto ships and sent to the consumer markets. Therefore, the corrosion resistance of carbon steel by concentrated acid will become a great concern for the mentioned storage and transportation. When the carbon steel comes into contact with concentrated sulfuric acid, there is an immediate acid attack with the formation of hydrogen gas and ferrous ions which, in turn, forms a protective layer of FeSO{sub 4} on the metallic surface. The durability of the tanks and pipes made of carbon steel will depend on the preservation of this protective layer. This work presents a review of the carbon steel corrosion in concentrated sulfuric acid and discusses the preventive methods against this corrosion, including anodic protection. (author)

Benthic Trophic Interactions in an Antarctic Shallow Water Ecosystem Affected by Recent Glacier Retreat.

Directory of Open Access Journals (Sweden)

Francesca Pasotti

Full Text Available The western Antarctic Peninsula is experiencing strong environmental changes as a consequence of ongoing regional warming. Glaciers in the area are retreating rapidly and increased sediment-laden meltwater runoff threatens the benthic biodiversity at shallow depths. We identified three sites with a distinct glacier-retreat related history and different levels of glacial influence in the inner part of Potter Cove (King George Island, South Shetland Islands, a fjord-like embayment impacted since the 1950s by a tidewater glacier retreat. We compared the soft sediment meio- and macrofauna isotopic niche widths (δ13C and δ15N stable isotope analysis at the three sites to investigate possible glacier retreat-related influences on benthic trophic interactions. The isotopic niches were locally shaped by the different degrees of glacier retreat-related disturbance within the Cove. Wider isotopic niche widths were found at the site that has become ice-free most recently, and narrower niches at the older ice-free sites. At an intermediate state of glacier retreat-related disturbance (e.g. via ice-growler scouring species with different strategies could settle. The site at the earliest stage of post-retreat development was characterized by an assemblage with lower trophic redundancy. Generally, the isotopic niche widths increased with increasing size spectra of organisms within the community, excepting the youngest assemblage, where the pioneer colonizer meiofauna size class displayed the highest isotopic niche width. Meiofauna at all sites generally occupied positions in the isotopic space that suggested a detrital-pool food source and/or the presence of predatory taxa. In general ice scour and glacial impact appeared to play a two-fold role within the Cove: i either stimulating trophic diversity by allowing continuous re-colonization of meiofaunal species or, ii over time driving the benthic assemblages into a more compact trophic structure with

Benthic Trophic Interactions in an Antarctic Shallow Water Ecosystem Affected by Recent Glacier Retreat.

Science.gov (United States)

Pasotti, Francesca; Saravia, Leonardo Ariel; De Troch, Marleen; Tarantelli, Maria Soledad; Sahade, Ricardo; Vanreusel, Ann

2015-01-01

The western Antarctic Peninsula is experiencing strong environmental changes as a consequence of ongoing regional warming. Glaciers in the area are retreating rapidly and increased sediment-laden meltwater runoff threatens the benthic biodiversity at shallow depths. We identified three sites with a distinct glacier-retreat related history and different levels of glacial influence in the inner part of Potter Cove (King George Island, South Shetland Islands), a fjord-like embayment impacted since the 1950s by a tidewater glacier retreat. We compared the soft sediment meio- and macrofauna isotopic niche widths (δ13C and δ15N stable isotope analysis) at the three sites to investigate possible glacier retreat-related influences on benthic trophic interactions. The isotopic niches were locally shaped by the different degrees of glacier retreat-related disturbance within the Cove. Wider isotopic niche widths were found at the site that has become ice-free most recently, and narrower niches at the older ice-free sites. At an intermediate state of glacier retreat-related disturbance (e.g. via ice-growler scouring) species with different strategies could settle. The site at the earliest stage of post-retreat development was characterized by an assemblage with lower trophic redundancy. Generally, the isotopic niche widths increased with increasing size spectra of organisms within the community, excepting the youngest assemblage, where the pioneer colonizer meiofauna size class displayed the highest isotopic niche width. Meiofauna at all sites generally occupied positions in the isotopic space that suggested a detrital-pool food source and/or the presence of predatory taxa. In general ice scour and glacial impact appeared to play a two-fold role within the Cove: i) either stimulating trophic diversity by allowing continuous re-colonization of meiofaunal species or, ii) over time driving the benthic assemblages into a more compact trophic structure with increased

Can shrubs help to reconstruct historical glacier retreats?

International Nuclear Information System (INIS)

Buras, Allan; Hallinger, Martin; Wilmking, Martin

2012-01-01

In the 21st century, most of the world’s glaciers are expected to retreat due to further global warming. The range of this predicted retreat varies widely as a result of uncertainties in climate and glacier models. To calibrate and validate glacier models, past records of glacier mass balance are necessary, which often only span several decades. Long-term reconstructions of glacier mass balance could increase the precision of glacier models by providing the required calibration data. Here we show the possibility of applying shrub growth increments as an on-site proxy for glacier summer mass balance, exemplified by Salix shrubs in Finse, Norway. We further discuss the challenges which this method needs to meet and address the high potential of shrub growth increments for reconstructing glacier summer mass balance in remote areas. (letter)

Variability, trends, and predictability of seasonal sea ice retreat and advance in the Chukchi Sea

Science.gov (United States)

Serreze, Mark C.; Crawford, Alex D.; Stroeve, Julienne C.; Barrett, Andrew P.; Woodgate, Rebecca A.

2016-10-01

As assessed over the period 1979-2014, the date that sea ice retreats to the shelf break (150 m contour) of the Chukchi Sea has a linear trend of -0.7 days per year. The date of seasonal ice advance back to the shelf break has a steeper trend of about +1.5 days per year, together yielding an increase in the open water period of 80 days. Based on detrended time series, we ask how interannual variability in advance and retreat dates relate to various forcing parameters including radiation fluxes, temperature and wind (from numerical reanalyses), and the oceanic heat inflow through the Bering Strait (from in situ moorings). Of all variables considered, the retreat date is most strongly correlated (r ˜ 0.8) with the April through June Bering Strait heat inflow. After testing a suite of statistical linear models using several potential predictors, the best model for predicting the date of retreat includes only the April through June Bering Strait heat inflow, which explains 68% of retreat date variance. The best model predicting the ice advance date includes the July through September inflow and the date of retreat, explaining 67% of advance date variance. We address these relationships by discussing heat balances within the Chukchi Sea, and the hypothesis of oceanic heat transport triggering ocean heat uptake and ice-albedo feedback. Developing an operational prediction scheme for seasonal retreat and advance would require timely acquisition of Bering Strait heat inflow data. Predictability will likely always be limited by the chaotic nature of atmospheric circulation patterns.

Preparation of a novel carbon-based solid acid from cassava stillage residue and its use for the esterification of free fatty acids in waste cooking oil.

Science.gov (United States)

Wang, Lingtao; Dong, Xiuqin; Jiang, Haoxi; Li, Guiming; Zhang, Minhua

2014-04-01

A novel carbon-based solid acid catalyst was prepared by the sulfonation of incompletely carbonized cassava stillage residue (CSR) with concentrated sulfuric acid, and employed to catalyze the esterification of methanol and free fatty acids (FFAs) in waste cooking oil (WCO). The effects of the carbonization and the sulfonation temperatures on the pore structure, acid density and catalytic activity of the CSR-derived catalysts were systematically investigated. Low temperature carbonization and high temperature sulfonation can cause the collapse of the carbon framework, while high temperature carbonization is not conducive to the attachment of SO3H groups on the surface. The catalyst showed high catalytic activity for esterification, and the acid value for WCO is reduced to below 2mg KOH/g after reaction. The activity of catalyst can be well maintained after five cycles. CSR can be considered a promising raw material for the production of a new eco-friendly solid acid catalyst. Copyright © 2014 Elsevier Ltd. All rights reserved.

Re-treatment tuberculosis cases categorised as "other": are they properly managed?

Directory of Open Access Journals (Sweden)

Hannock Tweya

Full Text Available BACKGROUND: Although the World Health Organization (WHO provides information on the number of TB patients categorised as "other", there is limited information on treatment regimens or treatment outcomes for "other". Such information is important, as inappropriate treatment can lead to patients remaining infectious and becoming a potential source of drug resistance. Therefore, using a cohort of TB patients from a large registration centre in Lilongwe, Malawi, our study determined the proportion of all TB re-treatment patients who were registered as "other", and described their characteristics and treatment outcomes. METHODS: This retrospective observational study used routine program data to determine the proportion of all TB re-treatment patients who were registered as "other" and describe their characteristics and treatment outcomes between January 2006 and December 2008. RESULTS: 1,384 (12% of 11,663 TB cases were registered as re-treatment cases. Of these, 898 (65% were categorised as "other": 707 (79% had sputum smear-negative pulmonary TB and 191 (21% had extra pulmonary TB. Compared to the smear-positive relapse, re-treatment after default (RAD and failure cases, smear-negative "other" cases were older than 34 years and less likely to have their HIV status ascertained. Among those with known HIV status, "other" TB cases were more likely to be HIV positive. Of TB patients categorised as "other", 462 (51% were managed on the first-line regimen with a treatment success rate of 63%. CONCLUSION: A large proportion of re-treatment patients were categorised as "other". Many of these patients were HIV-infected and over half were treated with a first-line regimen, contrary to national guidelines. Treatment success was low. More attention to recording, diagnosis and management of these patients is warranted as incorrect treatment regimen and poor outcomes could lead to the development of drug resistant forms of TB.

A glassy carbon electrode modified with a nickel(II) norcorrole complex and carbon nanotubes for simultaneous or individual determination of ascorbic acid, dopamine, and uric acid

International Nuclear Information System (INIS)

Deng, Keqin; Li, Xiaofang; Huang, Haowen

2016-01-01

The authors report on the synthesis of a hybrid material consisting of the porphyrinoid metal complex nickel(II) norcorrole that was noncovalently bound to carbon nanotubes (CNT-NiNC). The hybrid was characterized by UV–vis, FTIR spectroscopy, and thermogravimetric analysis. The CNT-NiNC hybrid possesses high catalytic activity and selectivity toward the oxidation of ascorbic acid, dopamine, and uric acid. It was used to modify a glassy carbon electrode which then is shown to enable simultaneous or individual determination of ascorbic acid (AA), dopamine (DA), and uric acid (UA) at pH 6.5 and typical working potentials of −70, 200 and 380 mV (vs. SCE). The detection limits (at an SNR of 3) are 2.0 μM for AA, 0.1 μM for DA, and 0.4 μM for UA. (author)

In situ synthesis carbonated hydroxyapatite layers on enamel slices with acidic amino acids by a novel two-step method

International Nuclear Information System (INIS)

Wu, Xiaoguang; Zhao, Xu; Li, Yi; Yang, Tao; Yan, Xiujuan; Wang, Ke

2015-01-01

In situ fabrication of carbonated hydroxyapatite (CHA) remineralization layer on an enamel slice was completed in a novel, biomimetic two-step method. First, a CaCO 3 layer was synthesized on the surface of demineralized enamel using an acidic amino acid (aspartic acid or glutamate acid) as a soft template. Second, at the same concentration of the acidic amino acid, rod-like carbonated hydroxyapatite was produced with the CaCO 3 layer as a sacrificial template and a reactant. The morphology, crystallinity and other physicochemical properties of the crystals were characterized using field emission scanning electron microscopy (FESEM), Fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD) and energy-dispersive X-ray analysis (EDAX), respectively. Acidic amino acid could promote the uniform deposition of hydroxyapatite with rod-like crystals via absorption of phosphate and carbonate ions from the reaction solution. Moreover, compared with hydroxyapatite crystals coated on the enamel when synthesized by a one-step method, the CaCO 3 coating that was synthesized in the first step acted as an active bridge layer and sacrificial template. It played a vital role in orienting the artificial coating layer through the template effect. The results show that the rod-like carbonated hydroxyapatite crystals grow into bundles, which are similar in size and appearance to prisms in human enamel, when using the two-step method with either aspartic acid or acidic glutamate (20.00 mmol/L). - Graphical abstract: FESEM images of enamel slices etched for 60 s and repaired by the two-step method with Glu concentration of 20.00 mmol/L. (A) The boundary (dotted line) of the repaired areas (b) and unrepaired areas (a). (Some selected areas of etched enamel slices were coated with a nail polish before the reaction, which was removed by acetone after the reaction); (B) high magnification image of Ga, (C) high magnification image of Gb. In situ fabrication of carbonated

In situ synthesis carbonated hydroxyapatite layers on enamel slices with acidic amino acids by a novel two-step method

Energy Technology Data Exchange (ETDEWEB)

Wu, Xiaoguang [Department of Pediatric Dentistry, The Hospital of Stomatology, Jilin University, Changchun 130021 (China); Zhao, Xu [College of Chemistry, Jilin University, Changchun 130021 (China); Li, Yi, E-mail: lyi99@jlu.edu.cn [Department of Pediatric Dentistry, The Hospital of Stomatology, Jilin University, Changchun 130021 (China); Yang, Tao [Department of Stomatology, Children' s Hospital of Changchun, 130051 (China); Yan, Xiujuan; Wang, Ke [Department of Pediatric Dentistry, The Hospital of Stomatology, Jilin University, Changchun 130021 (China)

2015-09-01

In situ fabrication of carbonated hydroxyapatite (CHA) remineralization layer on an enamel slice was completed in a novel, biomimetic two-step method. First, a CaCO{sub 3} layer was synthesized on the surface of demineralized enamel using an acidic amino acid (aspartic acid or glutamate acid) as a soft template. Second, at the same concentration of the acidic amino acid, rod-like carbonated hydroxyapatite was produced with the CaCO{sub 3} layer as a sacrificial template and a reactant. The morphology, crystallinity and other physicochemical properties of the crystals were characterized using field emission scanning electron microscopy (FESEM), Fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD) and energy-dispersive X-ray analysis (EDAX), respectively. Acidic amino acid could promote the uniform deposition of hydroxyapatite with rod-like crystals via absorption of phosphate and carbonate ions from the reaction solution. Moreover, compared with hydroxyapatite crystals coated on the enamel when synthesized by a one-step method, the CaCO{sub 3} coating that was synthesized in the first step acted as an active bridge layer and sacrificial template. It played a vital role in orienting the artificial coating layer through the template effect. The results show that the rod-like carbonated hydroxyapatite crystals grow into bundles, which are similar in size and appearance to prisms in human enamel, when using the two-step method with either aspartic acid or acidic glutamate (20.00 mmol/L). - Graphical abstract: FESEM images of enamel slices etched for 60 s and repaired by the two-step method with Glu concentration of 20.00 mmol/L. (A) The boundary (dotted line) of the repaired areas (b) and unrepaired areas (a). (Some selected areas of etched enamel slices were coated with a nail polish before the reaction, which was removed by acetone after the reaction); (B) high magnification image of Ga, (C) high magnification image of Gb. In situ fabrication of

Damage to root dentin during retreatment procedures

NARCIS (Netherlands)

Shemesh, H.; Roeleveld, A.C.; Wesselink, P.R.; Wu, M.K.

2011-01-01

Introduction: The aim of this study was to explore the influence of retreatment procedures on the appearance of defects on the root canal walls. Methods: Two hundred mandibular premolars were divided into 4 groups. One group was left unprepared. The rest of the teeth were prepared with ProTaper

Neutralization of acid-mine water with calcium-carbonate

CSIR Research Space (South Africa)

Maree, JP

1994-01-01

Full Text Available Traditionally, Lime is used for the neutralization of acidic effluents. Calcium carbonate should be considered as an alternative because of considerations such as lower cost, low solubility at pH values greater than 7 and simple dosing system...

Retreating academics: creating spaces for the scholarship of ...

African Journals Online (AJOL)

, this paper explores particular spaces created to support academic engagement in the scholarship of teaching and learning: the space of writing retreats. The metaphor of 'tapestry' is used to capture the development of a complex conceptual ...

Reasons for Retreatment of Amalgam and Composite Restorations among the Patients Referring to Tabriz Faculty of Dentistry

Directory of Open Access Journals (Sweden)

Siavash Savadi Oskoee

2007-06-01

Full Text Available

Background and aims. Retreatment of existing restorations not only requires a lot of money and time but also there is a danger of weakening tooth structure and irritating the pulp. Since awareness of the reasons for the retreatment of teeth will save the teeth from possible future failure, the aim of this study was to assess the reasons for retreatment of amalgam and composite restorations in patients referring to Tabriz Faculty of Dentistry.

Materials and methods. In this descriptive study, the subjects had previously received an amalgam or a composite restoration in the Operative Department by dental students and were judged to need retreatment in their second visit. A total of 300 defective teeth were selected by simple random sampling method. The data was collected through examination and questionnaires and analyzed using chi-square test.

Results. There was a statistically significant association between the type of the restorative material and the reason for retreatment (p=0.001.

Conclusion. Although the reasons for the retreatment of amalgam and composite restorations were different, recurrent caries was the main reason for the retreatment for both restorative materials.

Effect of surface acidic oxides of activated carbon on adsorption of ammonia.

Science.gov (United States)

Huang, Chen-Chia; Li, Hong-Song; Chen, Chien-Hung

2008-11-30

The influence of surface acidity of activated carbon (AC) was experimentally studied on adsorption of ammonia (NH(3)). Coconut shell-based AC was modified by various acids at different concentrations. There were five different acids employed to modified AC, which included nitric acid, sulfuric acid, hydrochloric acid, phosphoric acid, and acetic acid. Acidic functional groups on the surface of ACs were determined by a Fourier transform infrared spectrograph (FTIR) and by the Boehm titration method. Specific surface area and pore volume of the ACs were measured by a nitrogen adsorption apparatus. Adsorption amounts of NH(3) onto the ACs were measured by a dynamic adsorption system at room temperature according to the principle of the ASTM standard test method. The concentration of NH(3) in the effluent stream was monitored by a gas-detecting tube technique. Experimental results showed that adsorption amounts of NH(3) on the modified ACs were all enhanced. The ammonia adsorption amounts on various activated carbons modified by different acids are in the following order: nitric acid>sulfuric acid>acetic acid approximately phosphoric acid>hydrochloric acid. It is worth to note that the breakthrough capacity of NH(3) is linearly proportional to the amount of acidic functional groups of the ACs.

EFFECTS OF MINERAL ADMIXTURE ON THE CARBONIC ACID LEACHING RESISTANCE OF CEMENT-BASED MATERIALS

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Yun Dong

2017-07-01

Full Text Available In order to reveal the degradation process and deterioration mechanism of cement-based materials, this paper analyzes the effects of carbonic acid leaching on the mechanical strength of mortars, as well as relative mass loss, microstructure, and composition of various cement pastes. The results indicate that cement pastes containing less than 20 % fly ash have higher carbonic acid leaching resistance than cement pastes without fly ash. However, after carbonic acid leaching, the compressive strength of the samples with fly ash is lower than that of the cement pastes without fly ash. The leaching resistance is good for samples cured at an early age before leaching. Carbonic acid leaching proceeds from the paste surface to the interior. The incorporation of an appropriate amount of slag powder helps to increase the density of the paste. Due to the pozzolanic activity of fly ash at late-stage leaching, a mixture of fly ash (≤ 20 % and slag powder (≤ 20 % effectively improves carbonic acid leaching resistance. The products of early-stage leaching were mainly CaCO₃ and small amounts of SiO₂ and Fe₂O₃. The C-S-H phase at the paste surface suffered serious damage after long periods of leaching, and the main products of leaching were SiO₂ and Fe₂O₃.

Risk Factors for Retreatment Following Myopic LASIK with Femtosecond Laser and Custom Ablation for the Treatment of Myopia.

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Kruh, Jonathan N; Garrett, Kenneth A; Huntington, Brian; Robinson, Steve; Melki, Samir A

2017-01-01

To identify risks factors for retreatment post-laser in situ keratomeliusis (LASIK). A retrospective chart review from December 2008 to September 2012 identified 1,402 patients (2,581 eyes) that underwent LASIK treatment for myopia with the Intralase™ FS, STAR S4 IR™ Excimer Laser, and WaveScan WaveFront™ technology. In this group, 83 patients were retreated. All charts were reviewed for preoperative age, gender, initial manifest refraction spherical equivalent (MRSE), total astigmatism, and iris registration. Increased incidence rates of retreatment post-LASIK were preoperative age >40 years (p -3.0 D (p = 0.02), and astigmatism >1D (p = 0.001). Iris registration capture did not significantly reduce the retreatment rate (p = 0.12). Risk factors for retreatment included preoperative age >40 years, initial MRSE > -3.0 D, and astigmatism >1D. There was no difference in retreatment rate for patients based on gender or iris registration capture.

Determination of ascorbic acid in pharmaceutical preparation and fruit juice using modified carbon paste electrode

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Simona Žabčíková

2016-06-01

Full Text Available Acrobic acid is key substance in the human metabolism and the rapid and accurate determination in food is of a great interest. Ascorbic acid is an electroactive compound, however poorly responded on the bare carbon paste electrodes. In this paper, brilliant cresyl blue and multi-walled carbon nanotubes were used for the modification of carbon paste electrode. Brilliant cresyl blue acts as a mediator improving the transition of electrons, whereas multiwalled carbon nanotubes increased the surface of the electrode. Both brilliant cresyl blue and multiwalled carbon nanotubes were added directly to the composite material. The electrochemical behavior of modified electode was determined in electrolyte at various pH, and the effect of the scan rate was also performed. It was shown that the electrochemical process on the surface of the modified carbon paste electrode was diffusion-controlled. The resulted modified carbon paste electrode showed a good electrocatalytic activity towards the oxidation of ascorbic acid at a reduced overpotential of +100 mV descreasing the risk of interferences. A linear response of the ascorbic acid oxidation current measured by the amperometry in the range of 0.1 - 350 µmol.L-1 was obtained applying the sensor for the standard solution. The limit of detection and limit of quantification was found to be 0.05 and 0.15 µmol.L-1, respectively. The novel method was applied for the determination of ascorbic acid in pharmaceutical vitamin preparation and fruit juice, and the results were in good agreement with the standard HPLC method. The presented modification of carbon paste electrode is suitable for the fast, sensitive and very accurate determination of ascorbic acid in fruit juices and pharmaceutical preparation.

Investigations into localized re-treatment of the retina with a 3-nanosecond laser.

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Chidlow, Glyn; Plunkett, Malcolm; Casson, Robert J; Wood, John P M

2016-08-01

Subvisual retinal lasers necessarily cause clinically invisible lesions, hence, they could intentionally or inadvertently be targeted at precisely the same or an overlapping location during repeat laser treatment. Herein, we investigated the structural integrity and cellular responses of localized re-treatment using a nanosecond laser (2RT) currently in trials for early age-related macular degeneration. Rats were randomly assigned to one of five groups: sham, subvisual 2RT, subvisual 2RT re-treatment, visual effect 2RT, visual effect 2RT re-treatment. Re-treatment groups were lasered on days 0 and 21; single laser groups were only lasered on day 21. All rats were euthanized at day 28 and eyes were then dissected and processed for immunohistochemistry. For re-treatment, the laser was targeted at precisely the same locations on both delivery occasions. Analytical endpoints included monitoring of retinal vascular integrity overlying lesions, investigation into any potential choroidal neovascularization, assessment of the RPE, quantification of collateral injury to photoreceptors or other neuronal classes, and delineation of glial reactivity. Repeat laser administration to rats caused ostensibly identical retinal-RPE-choroid responses to those obtained in age-matched rats that received only a single application. Specifically, 7 days after treatment, RPE cells were re-populating lesion sites. No obvious consistent differences were evident between the single and repeat laser groups. Moreover, repeat laser caused no (measurable) additive injury to photoreceptors or other retinal neuronal classes from single laser treatment. In re-lasered animals, there was no increase in microglial activity overlying and adjacent to lesion sites relative to single lasered rats. Finally, there was no evidence of choroidal neovascularization after repeat laser treatment. The overall results provide a measure of confidence that re-treatment of patients with 2RT should not provide any

MEASURING SURFACE DEFORMATION IN GLACIER RETREATED AREAS BASED ON PS-INSAR – GELADANDONG GLACIER AS A CASE STUDY

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B. Mohamadi

2018-04-01

Full Text Available Glaciers are retreating in many parts of the world as a result of global warming. Many researchers consider Qinghai-Tibetan Plateau as a reference for climate change by measuring glaciers retreat on the plateau. This retreat resulted in some topographic changes in retreated areas, and in some cases can lead to geohazards as landslides, and rock avalanches, which is known in glacier retreated areas as paraglacial slope failure (PSF. In this study, Geladandong biggest and main glacier mass was selected to estimate surface deformation on its glacier retreated areas and define potential future PSF based on PS-InSAR technique. 56 ascending and 49 descending images were used to fulfill this aim. Geladandong glacier retreated areas were defined based on the maximum extent of the glacier in the little ice age. Results revealed a general uplift in the glacier retreated areas with velocity less than 5mm/year. Obvious surface motion was revealed in seven parts surround glacier retreated areas with high relative velocity reached ±60mm/year in some parts. Four parts were considered as PSF potential motion, and two of them showed potential damage for the main road in the study area in case of rock avalanche into recent glacier lakes that could result in glacier lake outburst flooding heading directly to the road. Finally, further analysis and field investigations are needed to define the main reasons for different types of deformation and estimate future risks of these types of surface motion in the Qinghai-Tibetan Plateau.

Biosynthesis of 2-hydroxyisobutyric acid (2-HIBA from renewable carbon

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Müller Roland H

2010-02-01

Full Text Available Abstract Nowadays a growing demand for green chemicals and cleantech solutions is motivating the industry to strive for biobased building blocks. We have identified the tertiary carbon atom-containing 2-hydroxyisobutyric acid (2-HIBA as an interesting building block for polymer synthesis. Starting from this carboxylic acid, practically all compounds possessing the isobutane structure are accessible by simple chemical conversions, e. g. the commodity methacrylic acid as well as isobutylene glycol and oxide. During recent years, biotechnological routes to 2-HIBA acid have been proposed and significant progress in elucidating the underlying biochemistry has been made. Besides biohydrolysis and biooxidation, now a bioisomerization reaction can be employed, converting the common metabolite 3-hydroxybutyric acid to 2-HIBA by a novel cobalamin-dependent CoA-carbonyl mutase. The latter reaction has recently been discovered in the course of elucidating the degradation pathway of the groundwater pollutant methyl tert-butyl ether (MTBE in the new bacterial species Aquincola tertiaricarbonis. This discovery opens the ground for developing a completely biotechnological process for producing 2-HIBA. The mutase enzyme has to be active in a suitable biological system producing 3-hydroxybutyryl-CoA, which is the precursor of the well-known bacterial bioplastic polyhydroxybutyrate (PHB. This connection to the PHB metabolism is a great advantage as its underlying biochemistry and physiology is well understood and can easily be adopted towards producing 2-HIBA. This review highlights the potential of these discoveries for a large-scale 2-HIBA biosynthesis from renewable carbon, replacing conventional chemistry as synthesis route and petrochemicals as carbon source.

Orthograde endodontic retreatment of teeth with individual cast posts: Report of two cases

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Ramić Bojana

2012-01-01

Full Text Available Introduction. The failure of primary endodontic treatment is manifested by various clinical symptoms following endodontic therapy or, more frequently, by the development of chronic inflammatory process in the apex region without any subjective symptoms. In case of unfavorable outcome of the primary endodontic treatment, orthograde endodontic retreatment is the method of choice for a prolonged therapy. Outline of Cases. Two female patients, 47 and 44 years old, were presented at the Dental Clinic of Vojvodina for endodontic retreatment of teeth 22, 23 and 13, within the repeated prosthetic restoration. Intraradicular individual cast posts were removed using ultrasonic instruments. Remains of gutta-percha were removed by engine driven rotary re-treatment files, root canals were shaped and cleaned using the crown-down technique, and obturated with gutta-percha and epoxy-resin-based sealer using the lateral compaction technique. Conclusion. When there are metal posts or broken instruments in the root canal, the use of ultrasonic instruments is considered a safe method characterized by negligible tooth substance loss and minimal root damage causing fractures and perforations, and the entire procedure is effective and predictable. Non-surgical orthograde endodontic retreatment, when properly performed in accessible and penetrable root canals, achieves a high cure rate, good and lasting results and eliminates the need for radical procedures, such as apical surgery or tooth extraction. When nonsurgical endodontic retreatment is done, treated teeth must be restored by full coronal coverage as soon as possible, to prevent coronal leakage or fracture.

Online stable carbon isotope ratio measurement in formic acid, acetic acid, methanol and ethanol in water by high performance liquid chromatography-isotope ratio mass spectrometry

International Nuclear Information System (INIS)

Tagami, Keiko; Uchida, Shigeo

2008-01-01

A suitable analysis condition was determined for high performance liquid chromatography-isotope ratio mass spectrometry (HPLC-IRMS) while making sequential measurements of stable carbon isotope ratios of δ 13 C in formic acid, acetic acid, methanol and ethanol dissolved in water. For this online column separation method, organic reagents are not applicable due to carbon contamination; thus, water and KH 2 PO 4 at low concentrations were tested as mobile phase in combination with a HyPURITY AQUASTAR TM column. Formic acid, acetic acid, methanol and ethanol were separated when 2 mM KH 2 PO 4 aqueous solution was used. Under the determined analysis condition for HPLC-IRMS, carbon concentrations could be measured quantitatively as well as carbon isotope ratio when carbon concentration was higher than 0.4 mM L for each chemical

Fluorescently labeled bionanotransporters of nucleic acid based on carbon nanotubes

International Nuclear Information System (INIS)

Novopashina, D.S.; Apartsin, E.K.; Venyaminova, A.G.

2012-01-01

We propose an approach to the design of a new type of hybrids of oligonucleotides with fluorescein-functionalized single-walled carbon nanotubes. The approach is based on stacking interactions of functionalized nanotubes with pyrene residues in conjugates of oligonucleotides. The amino- and fluorescein-modified single walled carbon nanotubes are obtained, and their physico-chemical properties are investigated. The effect of the functionalization type of carbon nanotubes on the efficacy of the sorption of pyrene conjugates of oligonucleotides was examined. The proposed noncovalent hybrids of fluorescein-labeled carbon nanotubes with oligonucleotides may be used for the intracellular transport of functional nucleic acids.

Means of Slope Retreat on the Na Pali Cliffs, Kauai, Hawaii

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Osborn, G.; Sheardown, A.; Blay, C.

2016-12-01

The spectacular, 500 to 600 m high, deeply grooved escarpment referred to as the Na Pali cliffs, on the northwest coast of Kauai, requires a substrate competent enough to hold up high steep cliffs yet erodible enough to allow generation of wide, deep grooves. These opposing tendencies are afforded by weathering of originally strong basalt that keeps pace with erosion. The fluted cliffs maintain a rather consistent slope angle, generally 50-60°, whether they are close to the shoreline or have retreated some distance from it, indicating that the slopes are retreating parallel to themselves. Previous literature promotes groundwater sapping or waterfall-plunge-pool erosion as the chief means of valley-head retreat, but there is no evidence that either concept provides a general explanation for retreat of the fluted cliffs. The eroding cliffs maintain steepness because as much rock is eroded at the base as at the top, and transported sediment is washed completely out of the gully system. The thin-bedded basalts exposed in the steep flutes are decomposed into irregularly alternating fine sediment of low to moderate cohesion and thoroughly fractured beds or lenses of solid but chemically weathered rock, and covered with a veneer of sparse grass. Erosion proceeds by episodic removal of thin grass-covered surficial sheets of the weathering products. Some of this process may be facilitated by shallow mass movement, but probably most of the work is done by overland and channelized flow during intense rainstorms. The Na Pali coast experiences one-hour rainfalls of 2-2.5 inches (1 year recurrence interval) and 5-6 inches (100 year recurrence interval); experiments by others on basaltic soils in Molokai suggest such rain is more than enough to generate erosion-inducing overland flow. Between the deep grooves and the shoreline are slopes with lesser drainage densities and lesser slope angles. The rocks here are not distinguished from the rocks above in previous literature, and

Climate Change and Glacier Retreat: Scientific Fact and Artistic Opportunity

Science.gov (United States)

Fagre, D. B.

2008-12-01

Mountain glaciers continue to retreat rapidly over most of the globe. In North America, at Glacier National Park, Montana, recent research results from Sperry Glacier (2005-2007) indicate negative mass balances are now 3-4 times greater than in the 1950s. A geospatial model of glacier retreat in the Blackfoot-Jackson basin suggested all glaciers would be gone by 2030 but has proved too conservative. Accelerated glacier shrinkage since the model was developed has mirrored an increase in actual annual temperature that is almost twice the rate used in the model. The glaciers in Glacier National Park are likely to be gone well before 2030. A variety of media, curricula, and educational strategies have been employed to communicate the disappearance of the glaciers as a consequence of global warming. These have included everything from print media and television coverage to podcasts and wayside exhibits along roads in the park. However, a new thrust is to partner with artists to communicate climate change issues to new audiences and through different channels. A scientist-artist retreat was convened to explore the tension between keeping artistic products grounded in factually-based reality while providing for freedom to express artistic creativity. Individual artists and scientists have worked to create aesthetic and emotional images, using painting, poetry, music and photography, to convey core messages from research on mountain ecosystems. Finally, a traveling art exhibit was developed to highlight the photography that systematically documents glacier change through time. The aim was to select photographs that provide the most compelling visual experience for an art-oriented viewer and also accurately reflect the research on glacier retreat. The exhibit opens on January 11, 2009

Psychological effects of a one-month meditation retreat on experienced meditators: the role of nonattachment

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Jesus Montero-Marin

2016-12-01

Full Text Available Background. There are few studies devoted to assessing the impact of meditation-intensive retreats on the well-being, positive psychology and personality of experienced meditators. We aimed to assess whether a 1-month Vipassana retreat: a would increase mindfulness and well-being; b would increase prosocial personality traits; and c whether psychological changes would be mediated and/or moderated by non-attachment.Method. A controlled, non-randomized, pre-post-intervention trial was used. The intervention group was a convenience sample (n=19 of experienced meditators who participated in a 1-month Vipassana meditation retreat. The control group (n=19 comprised matched experienced meditators who did not take part in the retreat. During the retreat, the mean duration of daily practice was 8-9 hours, the diet was vegetarian and silence was compulsory. The Experiences Questionnaire (EQ, Non-Attachment Scale (NAS, Positive and Negative Affect Schedule (PANAS, Satisfaction With Life Scale (SWLS, Temperament Character Inventory Revised (TCI-R-67, Five Facets Mindfulness Questionnaire (FFMQ, Self-Other Four Immeasurables (SOFI and the MINDSENS Composite Index were administered. ANCOVAs and linear regression models were used to assess pre-post changes and mediation/moderation effects.Results. Compared to controls, retreatants showed increases in non-attachment, observing, MINDSENS, positive-affect, balance-affect and cooperativeness; and decreases in describing, negative-others, reward-dependence and self-directedness. Non-attachment had a mediating role in decentring, acting aware, non-reactivity, negative-affect, balance-affect and self-directedness; and a moderating role in describing and positive others, with both mediating and moderating effects on satisfaction with life.Conclusions. A 1-month Vipassana meditation retreat seems to yield improvements in mindfulness, well-being and personality, even in experienced meditators. Non-attachment might

Sub-ice-shelf sediments record history of twentieth-century retreat of Pine Island Glacier.

Science.gov (United States)

Smith, J A; Andersen, T J; Shortt, M; Gaffney, A M; Truffer, M; Stanton, T P; Bindschadler, R; Dutrieux, P; Jenkins, A; Hillenbrand, C-D; Ehrmann, W; Corr, H F J; Farley, N; Crowhurst, S; Vaughan, D G

2017-01-05

The West Antarctic Ice Sheet is one of the largest potential sources of rising sea levels. Over the past 40 years, glaciers flowing into the Amundsen Sea sector of the ice sheet have thinned at an accelerating rate, and several numerical models suggest that unstable and irreversible retreat of the grounding line-which marks the boundary between grounded ice and floating ice shelf-is underway. Understanding this recent retreat requires a detailed knowledge of grounding-line history, but the locations of the grounding line before the advent of satellite monitoring in the 1990s are poorly dated. In particular, a history of grounding-line retreat is required to understand the relative roles of contemporaneous ocean-forced change and of ongoing glacier response to an earlier perturbation in driving ice-sheet loss. Here we show that the present thinning and retreat of Pine Island Glacier in West Antarctica is part of a climatically forced trend that was triggered in the 1940s. Our conclusions arise from analysis of sediment cores recovered beneath the floating Pine Island Glacier ice shelf, and constrain the date at which the grounding line retreated from a prominent seafloor ridge. We find that incursion of marine water beyond the crest of this ridge, forming an ocean cavity beneath the ice shelf, occurred in 1945 (±12 years); final ungrounding of the ice shelf from the ridge occurred in 1970 (±4 years). The initial opening of this ocean cavity followed a period of strong warming of West Antarctica, associated with El Niño activity. Thus our results suggest that, even when climate forcing weakened, ice-sheet retreat continued.

Green synthesis of carbon dots from pork and application as nanosensors for uric acid detection

Science.gov (United States)

Zhao, Chunxi; Jiao, Yang; Hu, Feng; Yang, Yaling

2018-02-01

In this work, a green, simple, economical method was developed in the synthesis of fluorescent carbon dots using pork as carbon source. The as-prepared carbon dots exhibit exceptional advantages including high fluorescent quantum yield (17.3%) and satisfactory chemical stability. The fluorescence of carbon dots based nanosensor can be selectively and efficiently quenched by uric acid. This phenomenon was used to develop a fluorescent method for facile detection of uric acid within a linear range of 0.1-100 μM and 100-500 μM, with a detection limit of 0.05 μM (S/N = 3). Finally, the proposed method was successfully applied in the determination of uric acid in human serum and urine samples with satisfactory recoveries, which suggested that the new nanosensors have great prospect toward the detection of uric acid in human fluids.

Electrocatalytic Activity of Carbonized Nanostructured Polyanilines for Oxidation Reactions: Sensing of Nitrite Ions and Ascorbic Acid

International Nuclear Information System (INIS)

Micić, Darko; Šljukić, Biljana; Zujovic, Zoran; Travas-Sejdic, Jadranka; Ćirić-Marjanović, Gordana

2014-01-01

Highlights: • Carbonized PANIs prepared from various nanostructured PANI precursors • Electroanalytical performances of carbonized PANIs evaluated using voltammetry • Study of carbonized PANIs physico-chemical properties related to electroactivity • The lowest over-potential for NO 2 − oxidation at c-PANI (+0.87 V vs. SCE) • The lowest over-potential for ascorbic acid oxidation at both c-PANI and c-PANI-SSA - Abstract: A comparative study of the electrocatalytic activity of nitrogen-containing carbon nanomaterials, prepared by the carbonization of nanostructured polyaniline (PANI) salts, for the electrooxidation reactions is presented. Nanostructured PANI salts were synthesized by the oxidative polymerization of aniline with ammonium peroxydisulfate in an aqueous solution in the presence of 5-sulfosalicylic acid (PANI-SSA), 3,5-dinitrosalicylic acid (PANI-DNSA) as well as without added acid (PANI), and subsequently carbonized to c-PANI-SSA, c-PANI-DNSA and c-PANI, respectively. Glassy carbon tip was modified with nanostructured c-PANIs and used for the investigation of sensing of nitrite and ascorbic acid in aqueous solutions as model analytes by linear sweep voltammetry. All three types of the investigated c-PANIs gave excellent response to the nitrite ions and ascorbic acid electrooxidation. The lowest peak potential for nitrite ion oxidation exhibited c-PANI (+0.87 V vs. SCE), and for ascorbic acid oxidation both c-PANI and c-PANI-SSA (ca. + 0.13 V vs. SCE). Electrochemical data were correlated with structural and textural data obtained by Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, elemental and nitrogen sorption analysis

Intricate Conformational Tunneling in Carbonic Acid Monomethyl Ester.

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Linden, Michael M; Wagner, J Philipp; Bernhardt, Bastian; Bartlett, Marcus A; Allen, Wesley D; Schreiner, Peter R

2018-04-05

Disentangling internal and external effects is a key requirement for understanding conformational tunneling processes. Here we report the s- trans/ s- cis tunneling rotamerization of carbonic acid monomethyl ester (1) under matrix isolation conditions and make comparisons to its parent carbonic acid (3). The observed tunneling rate of 1 is temperature-independent in the 3-20 K range and accelerates when using argon instead of neon as the matrix material. The methyl group increases the effective half life (τ eff ) of the energetically disfavored s- trans-conformer from 3-5 h for 3 to 11-13 h for 1. Methyl group deuteration slows the rotamerization further (τ eff ≈ 35 h). CCSD(T)/cc-pVQZ//MP2/aug-cc-pVTZ computations of the tunneling probability suggest that the rate should be almost unaffected by methyl substitution or its deuteration. Thus the observed relative rates are puzzling, and they disagree with previous explanations involving fast vibrational relaxation after the tunneling event facilitated by the alkyl rotor.

Endodontic retreatment decisions: no consensus.

Science.gov (United States)

Aryanpour, S; Van Nieuwenhuysen, J P; D'Hoore, W

2000-05-01

The objectives of the present study were to: (i) evaluate the consensus, if any, amongst dental schools, students and their instructors managing the same clinical cases, all of which involved endodontically treated teeth; and (ii) determine the predominant proposed treatment option. Final year students, endodontic staff members and instructors of 10 European dental schools were surveyed as decision makers. Fourteen different radiographic cases of root canal treated teeth accompanied by a short clinical history were presented to them in a uniform format. For each case the decision makers were requested to: (i) choose only one out of nine treatment alternatives proposed, from 'no treatment' to 'extraction' via 'retreatment' and 'surgery' (ii) assess on two 5-point scales: the difficulty of making a decision, and the technical complexity of the retreatment procedure. The results indicate wide inter- and also intra-school disagreements in the clinical management of root canal treated teeth. Analysis of variance showed that the main source of variation was the 'school effect', explaining 1.8% (NS) to 18.6% (P < 0.0001) of the treatment variations. No other factor explained as much variance. Decision difficulty was moderately correlated to technical complexity (Pearsons' r ranging from 0.19 to 0.35, P < 0.0001). No clear consensus occurred amongst and within dental schools concerning the clinical management of the 14 cases. The lack of consensus amongst schools seems to be due mainly to chance or uncertainty, but can be partly explained by the 'school effect'.

Carbonic acid as a reserve of carbon dioxide on icy moons: The formation of carbon dioxide (CO2) in a polar environment

International Nuclear Information System (INIS)

Jones, Brant M.; Kaiser, Ralf I.; Strazzulla, Giovanni

2014-01-01

Carbon dioxide (CO 2 ) has been detected on the surface of several icy moons of Jupiter and Saturn via observation of the ν 3 band with the Near-Infrared Mapping Spectrometer on board the Galileo spacecraft and the Visible-Infrared Mapping Spectrometer on board the Cassini spacecraft. Interestingly, the CO 2 band for several of these moons exhibits a blueshift along with a broader profile than that seen in laboratory studies and other astrophysical environments. As such, numerous attempts have been made in order to clarify this abnormal behavior; however, it currently lacks an acceptable physical or chemical explanation. We present a rather surprising result pertaining to the synthesis of carbon dioxide in a polar environment. Here, carbonic acid was synthesized in a water (H 2 O)-carbon dioxide (CO 2 ) (1:5) ice mixture exposed to ionizing radiation in the form of 5 keV electrons. The irradiated ice mixture was then annealed, producing pure carbonic acid which was then subsequently irradiated, recycling water and carbon dioxide. However, the observed carbon dioxide ν 3 band matches almost exactly with that observed on Callisto; subsequent temperature program desorption studies reveal that carbon dioxide synthesized under these conditions remains in solid form until 160 K, i.e., the sublimation temperature of water. Consequently, our results suggest that carbon dioxide on Callisto as well as other icy moons is indeed complexed with water rationalizing the shift in peak frequency, broad profile, and the solid state existence on these relatively warm moons.

Biological regeneration of humic acid-loaded partially exhausted activated carbon (down flow system)

International Nuclear Information System (INIS)

Durrani, M.A.Q.J.; Martin, R.J.; Khaliq, F.

1995-01-01

This paper represents the report on the biological regeneration of partially exhausted (down flow) activated carbon following the experimental studies carried out at the university of Birmingham, UK. The Research investigated the extent of bio regeneration of humic acid of concentration 100 mg/l. Bio regeneration in the partial exhaustion system (down flow) was evaluated in terms of substrate removal. Bacterial counts in the effluents of regenerated GAC columns were significantly more than those of fresh carbon effluents. The regeneration performance of the bio regeneration, partially exhausted (with humic acid) carbon increased during initial cycles, later on, it deteriorated significantly with each successive regeneration cycle. Microbial fouling of the carbon, especially at the bottom of the carbon bed was found to produce a substantial deterioration of the bio regeneration performance. (author)

Carbonic anhydrase 5 regulates acid-base homeostasis in zebrafish.

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Ruben Postel

Full Text Available The regulation of the acid-base balance in cells is essential for proper cellular homeostasis. Disturbed acid-base balance directly affects cellular physiology, which often results in various pathological conditions. In every living organism, the protein family of carbonic anhydrases regulate a broad variety of homeostatic processes. Here we describe the identification, mapping and cloning of a zebrafish carbonic anhydrase 5 (ca5 mutation, collapse of fins (cof, which causes initially a collapse of the medial fins followed by necrosis and rapid degeneration of the embryo. These phenotypical characteristics can be mimicked in wild-type embryos by acetazolamide treatment, suggesting that CA5 activity in zebrafish is essential for a proper development. In addition we show that CA5 regulates acid-base balance during embryonic development, since lowering the pH can compensate for the loss of CA5 activity. Identification of selective modulators of CA5 activity could have a major impact on the development of new therapeutics involved in the treatment of a variety of disorders.

Hydrogen-bond acidic functionalized carbon nanotubes (CNTs) with covalently-bound hexafluoroisopropanol groups

Energy Technology Data Exchange (ETDEWEB)

Fifield, Leonard S.; Grate, Jay W.

2010-06-01

Fluorinated hydrogen-bond acidic groups are directly attached to the backbone of single walled carbon nanotubes (SWCNTs) without the introduction of intermediate electron donating surface groups. Hexafluoroalcohol functional groups are exceptionally strong hydrogen bond acids, and are added to the nanotube surface using the aryl diazonium approach to create hydrogen-bond acidic carbon nanotube (CNT) surfaces. These groups can promote strong hydrogen-bonding interactions with matrix materials in composites or with molecular species to be concentrated and sensed. In the latter case, this newly developed material is expected to find useful application in chemical sensors and in CNT-based preconcentrator devices for the detection of pesticides, chemical warfare agents and explosives.

Removal of Heavy Metal Ions with Acid Activated Carbons Derived from Oil Palm and Coconut Shells

Science.gov (United States)

Rahman, Mokhlesur M.; Adil, Mohd; Yusof, Alias M.; Kamaruzzaman, Yunus B.; Ansary, Rezaul H.

2014-01-01

In this work, batch adsorption experiments were carried out to investigate the suitability of prepared acid activated carbons in removing heavy metal ions such as nickel(II), lead(II) and chromium(VI). Acid activated carbons were obtained from oil palm and coconut shells using phosphoric acid under similar activation process while the differences lie either in impregnation condition or in both pretreatment and impregnation conditions. Prepared activated carbons were modified by dispersing hydrated iron oxide. The adsorption equilibrium data for nickel(II) and lead(II) were obtained from adsorption by the prepared and commercial activated carbons. Langmuir and Freundlich models fit the data well. Prepared activated carbons showed higher adsorption capacity for nickel(II) and lead(II). The removal of chromium(VI) was studied by the prepared acid activated, modified and commercial activated carbons at different pH. The isotherms studies reveal that the prepared activated carbon performs better in low concentration region while the commercial ones in the high concentration region. Thus, a complete adsorption is expected in low concentration by the prepared activated carbon. The kinetics data for Ni(II), Pb(II) and Cr(VI) by the best selected activated carbon fitted very well to the pseudo-second-order kinetic model. PMID:28788640

Removal of Heavy Metal Ions with Acid Activated Carbons Derived from Oil Palm and Coconut Shells

Directory of Open Access Journals (Sweden)

Mokhlesur M. Rahman

2014-05-01

Full Text Available In this work, batch adsorption experiments were carried out to investigate the suitability of prepared acid activated carbons in removing heavy metal ions such as nickel(II, lead(II and chromium(VI. Acid activated carbons were obtained from oil palm and coconut shells using phosphoric acid under similar activation process while the differences lie either in impregnation condition or in both pretreatment and impregnation conditions. Prepared activated carbons were modified by dispersing hydrated iron oxide. The adsorption equilibrium data for nickel(II and lead(II were obtained from adsorption by the prepared and commercial activated carbons. Langmuir and Freundlich models fit the data well. Prepared activated carbons showed higher adsorption capacity for nickel(II and lead(II. The removal of chromium(VI was studied by the prepared acid activated, modified and commercial activated carbons at different pH. The isotherms studies reveal that the prepared activated carbon performs better in low concentration region while the commercial ones in the high concentration region. Thus, a complete adsorption is expected in low concentration by the prepared activated carbon. The kinetics data for Ni(II, Pb(II and Cr(VI by the best selected activated carbon fitted very well to the pseudo-second-order kinetic model.

Power grid control in retreat

International Nuclear Information System (INIS)

Morch, Stein

2000-01-01

Bilateral grid control that obstructs free trade of electricity is in retreat. Negotiations on opening the Skagerrak cables are in progress. The EU, national authorities, network companies with system responsibility, market actors, electricity exchanges all push for quick opening of the grid. At present, free trade of electricity is hindered not so much by physical bottlenecks in the grid as by market actors possessing control and bilateral agreements. The article discusses current bilateral agreements and how they might affect the possibility of a free trade of electricity in Europe

Retreat of Stephenson Glacier, Heard Island, from Remote Sensing and Field Observations

Science.gov (United States)

Mitchell, W.; Schmieder, R.

2017-12-01

Heard Island (Australian sub-Antarctic territory, 53 S, 73.5 E) is a volcanic island mantled in glaciers, and a UNESCO World Heritage Site both for its geology and ecology. Lying to the south of the Antarctic Convergence, the changes in response to climate seen on Heard Island are likely to be a bellwether for areas further south. Beginning in 1999, American satellites (Landsat 7, EO-1, and Landsat 8) have produced images of the island on a roughly weekly basis. Although the island is often shrouded in clouds, clear images of at least portions of the island are plentiful enough to create a nearly-annual record of the toe of Stephenson Glacier. During this period, Stephenson Glacier retreated by nearly 5 km, and lost 50% of its area. As a result of this retreat, a portion of the glacier now could be classified as a separate glacier. Additionally, in 2016, terrestrial photographs of Stephenson Glacier were taken during a three-week expedition to Heard Island, which accessed the Stephenson Glacier area by boat via the proglacial Stephenson Lagoon. During that work, sonar indicated some depths in the lagoon exceeding 100 m. Much of the loss in glacier length and area occurred during the mid- and late-2000s, with retreat rates slowing toward 2017. At this time, the glacier has retreated so that the main toe is not far from the base of a tall ice falls, while another toe—perhaps now a separate glacier—is land-based. This type of retreat pattern, fast over water and slower on land, is typical of other tidewater glaciers. Further monitoring of Stephenson Glacier and other glaciers on Heard Island will continue using Landsat 8.

Efficacy of protaper next and protaper universal retreatment systems in removing gutta-percha in curved root canals during root canal retreatment.

Science.gov (United States)

Ozyurek, Taha; Ozsezer-Demiryurek, Ebru

2017-01-01

The aim of this study was to compare the cleanliness of root canal walls after retreatment using ProTaper Next (PTN), ProTaper Universal Retreatment (PTR) nickel-titanium (NiTi) systems and Hedström hand files in curved mesial canals of mandibular molar teeth and the time required for gutta-percha and sealer removal. Ninety mandibular molar teeth with curved mesial roots were instrumented up to #35.04 with Mtwo NiTi rotary instruments and obturated using the continuous wave of condensation technique. Removal of gutta-percha and sealer was performed using one of the following: PTN and PTR NiTi systems and Hedström hand files. Samples were placed on the VistaScan phosphor plates in the mesio-distal direction and the radiographs were taken. The digital radiographs were analyzed using AutoCAD software. Also, the total time required for gutta-percha removal was calculated by a chronometer. The total retreatment time was significantly shorter in the PTN and PTR groups compared with the manual group (p<0.05). There was a significant difference between the groups according to the total residual gutta-percha and sealer (p<0.05). The PTN and PTR groups left significantly less gutta-percha and sealer remnant than the manual group (p<0.001). Within the limitations of this study, the PTN and PTR groups showed less residual gutta-percha and sealer than the manual group. The NiTi rotary systems were significantly faster than the manual group in the time required for gutta-percha and sealer removal.

Desorption of uranium from titanium-activated carbon composite adsorbent with acidic eluent, 1

International Nuclear Information System (INIS)

Hirotsu, Takahiro; Fujii, Ayako; Sakane, Kohji; Katoh, Shunsaku; Sugasaka, Kazuhiko

1984-01-01

An investigation was carried out on the desorption of uranium from titanium-activated carbon composite adsorbent with acidic eluent by the batch process. The rate of desorption of uranium with acidic eluent depended on temperature, showing an increase as the temperature was raised. But the rate of desorption with acidic eluent was less dependent on temperature than that obtained when mixed eluent of sodium carbonate-sodium hydrogencarbonate was used. The rate of desorption of uranium did not vary in the range of concentration from 0.3 to 0.5 N, and the rate of desorption with sulfuric acid was slightly higher than that obtained when hydrochloric acid was used. The amount of dissolved titanium decreased as the ratio of adsorbent to eluent (RAE) was increased. At RAE of 10 %, the percentage of dissolved titanium (DTI) was below 0.38 % with sulfuric acid, below 0.7 % with hydrochloric acid. These values were found to be higher than the ones with the carbonate eluent. The elements except uranium, which were adsorbed on the adsorbent, were eluted simultaneously with acidic eluent. The regeneration of the adsorbent after desorption, therefore, was found to be unnecessary. In a repeated test of adsorption-desorption treatment up to five times, the percentage of uranium adsorbed from natural sea water was approximately constant of 85 %. From these results, the application of column process to the desorption of uranium with acidic eluent at room temperature was proposed to be feasible. (author)

Desorption of uranium from titanium-activated carbon composite adsorbent with acidic eluent, (1)

International Nuclear Information System (INIS)

Hirotsu, Takahiro; Fujii, Ayako; Sakane, Kohji; Katoh, Shunsaku; Sugasaka, Kazuhiko

1983-01-01

An investigation was carried out on the desorption of uranium from titanium-activated carbon composite adsorbent with acidic eluent by the batch process. The rate of desorption of uranium with acidic eluent depended on temperature, showing an increase as the temperature was raised. But the rate of desorption with acidic eluent was less dependent on temperature than that obtained when mixed eluent of sodium carbonate-sodium hydrogencarbonate was used. The difference of the rate of desorption of uranium in the range of concentration from 0.3 to 0.5N was not found, and the rate of desorption with sulfuric acid was slightly higher than that obtained when hydrochloric acid was used. The amount of dissolved titanium decreased as the ratio of adsorbent to eluent (RAE) was increased. At RAE of 10%, the percentage of dissolved titanium (DTI) was below 0.38% with sulfuric acid, below 0.7% with hydrochloric acid. These values were found to be higher than the ones with the carbonate eluent. The elements except uranium, which were adsorbed on the adsorbent, were eluted simultaneously with acidic eluent. The regeneration of the adsorbent after desorption, therefore, was found to be unnecessary. In a repeated test of adsorption-desorption treatment up to five times, the percentage of uranium adsorbed from natural sea water was approximately constant of 85%. From these results, the application of column process to the desorption of uranium with acidic eluent at room temperature was proposed to be feasible. (author)

Carbon components in the phosphoric acid fuel cell-an overview

International Nuclear Information System (INIS)

Appleby, J.

1983-01-01

The single breakthrough that has made the phosphoric acid fuel cell a practical reality has been the use of carbon or graphite components for the repeat parts of the cell stack. While the thermodynamic stability of carbon is such that rapid corrosion would be expected at the cathode at fuel cell operating temperature, its kinetic stability is remarkable despite the absence of passivating layers analogous to those on, for example, the Group VA elements niobium and tantalum. This happy accident, combined with the adequate electronic conductivity of the carbon materials used, has provided the opportunity to reduce fuel cell cost to attractive levels. The development of these carbon compounds is reviewed

Retreatment and outcomes of recurrent intracranial vertebral artery dissecting aneurysms after stent assisted coiling: a single center experience.

Directory of Open Access Journals (Sweden)

Ying Song

Full Text Available The retreatment of recurrent intracranial vertebral artery dissecting aneurysms (VADAs after stent assisted coiling (SAC has not yet been studied. The purpose of this study was to evaluate the strategies and outcomes for retreatment of recurrent VADAs after SAC.Between September 2009 and November 2013, six consecutive patients presenting with recurrent intracranial VADAs after SAC were enrolled in this study. They were all male with age ranging from 29 to 54 years (mean age, 46.2 years. The procedures of treatments and angiographic and clinical follow-up were reviewed retrospectively. Retreatment modalities were selected individually according to the characteristics of recurrence. The outcomes of retreatment were evaluated by angiographic and clinical follow-up.Six patients with recurrent intracranial VADAs after SAC were retreated, with second SAC in three patients, coil embolization, double overlapping stents placement and endovascular occlusion with aneurysm trapping in one patient, respectively. Immediate angiographic outcomes of retreatment were: complete occlusion in three patients, nearly complete occlusion in two patients, and contrast medium retention in dissecting aneurysm in one patient. All cases were technically successful. No complications related to endovascular procedures occurred. Angiographic follow-up was available in all five patients treated with second SAC or double overlapping stents, which was complete occlusion in four patients, obliteration of parent artery in one patient, showing no recurrence at 4-11 months (mean: 8.6 months. Clinical follow-up was performed in all six patients at 11-51 months after initial endovascular treatment and at 9-43 months after retreatment. The mRS of last clinical follow-up was excellent in five patients and mild disability in only one patient.Endovascular retreatment is feasible and effective for recurrent intracranial VADAs after SAC. Individualized strategies of retreatment should be

To evaluate and compare the efficacy, cleaning ability of hand and two rotary systems in root canal retreatment.

Science.gov (United States)

Shivanand, Sunita; Patil, Chetan R; Thangala, Venugopal; Kumar, Pabbati Ravi; Sachdeva, Jyoti; Krishna, Akash

2013-05-01

To evaluate and compare the efficacy, cleaning ability of hand and two rotary systems in root canal retreatment. Sixty extracted premolars were retreated with following systems: Group -ProTaper Universal retreatment files, Group 2-ProFile system, Group 3-H-file. Specimens were split longitudinally and amount of remaining gutta-percha on the canal walls was assessed using direct visual scoring with the aid of stereomicroscope. Results were statistically analyzed using ANOVA test. Completely clean root canal walls were not achieved with any of the techniques investigated. However, all three systems proved to be effective for gutta-percha removal. Significant difference was found between ProTaper universal retreatment file and H-file, and also between ProFile and H-file. Under the conditions of the present study, ProTaper Universal retreatment files left significantly less guttapercha and sealer than ProFile and H-file. Rotary systems in combination with gutta-percha solvents can perform superiorly as compared to the time tested traditional hand instrumentation in root canal retreatment.

Efficacy of Different Methods for Removing Root Canal Filling Material in Retreatment - An In-vitro Study.

Science.gov (United States)

Kasam, Swetha; Mariswamy, Annapoorna Ballagere

2016-06-01

Although success of endodontic therapy has significantly improved in the last few decades due to the introduction of novel materials and techniques, failures of endodontic therapy requiring re-treatment still comprise a significant percentage of patients requiring root canal treatment. To evaluate and compare the effective removal of gutta percha and sealer, amount of apical debris extrusion and time required for gutta percha removal using various endodontic files. Total 48 extracted mandibular premolars were mounted on acrylic blocks and endodontic procedure was carried out using size 40 K file and obturated using guttapercha and zinc oxide eugenol sealer. After one month storage, samples were decoronated, mounted on screw capped vials and subjected to removal of obturated material by four instruments: H files, safe sided H files, protaper universal retreatment rotary system and ultrasonic retreatment tip, grouped as 1, 2, 3, and 4 respectively. Only 2mm of obturated material from the coronal part was removed using no. 3 Gates Glidden drill, guttapercha was softened with a drop of xylene for 2 mins for each canal and retreatment was performed. The retreatment procedure was said to be complete when no visible debris were observed on the instrument flutes. The samples split into two halves and examined under stereomicroscope, photographed, assessed using AUTOCAD software and percentage of remaining filling material in coronal, middle, apical thirds of the canal was calculated in mm(2). Retreatment time was recorded in seconds and apically extruded debris was assessed by microbalance in grams for each tooth. The data was analyzed by using descriptive statistics, ANOVA and Scheffe's post hoc test through SPSS for windows (v 16.0). The ultrasonic retreatment tip had less percentage of residual guttapercha/sealer, shorter mean operating time and little apical extrusion with a significant difference (p<0.05) between the other groups. All techniques retained guttapercha

Efficacy of reciprocating and rotary NiTi instruments for retreatment of curved root canals assessed by micro-CT.

Science.gov (United States)

Rödig, T; Reicherts, P; Konietschke, F; Dullin, C; Hahn, W; Hülsmann, M

2014-10-01

To compare the efficacy of reciprocating and rotary NiTi-instruments in removing filling material from curved root canals using micro-computed tomography. Sixty curved root canals were prepared and filled with gutta-percha and sealer. After determination of root canal curvatures and radii in two directions as well as volumes of filling material, the teeth were assigned to three comparable groups (n = 20). Retreatment was performed using Reciproc, ProTaper Universal Retreatment or Hedström files. Percentages of residual filling material and dentine removal were assessed using micro-CT imaging. Working time and procedural errors were recorded. Statistical analysis was performed by variance procedures. No significant differences amongst the three retreatment techniques concerning residual filling material were detected (P > 0.05). Hedström files removed significantly more dentine than ProTaper Universal Retreatment (P  0.05). Reciproc and ProTaper Universal Retreatment were significantly faster than Hedström files (P = 0.0001). No procedural errors such as instrument fracture, blockage, ledging or perforation were detected for Hedström files. Three perforations were recorded for ProTaper Universal Retreatment, and in both NiTi groups, one instrument fracture occured. Remnants of filling material were observed in all samples with no significant differences between the three techniques. Hedström files removed significantly more dentine than ProTaper Universal Retreatment, but no significant differences between both NiTi systems were detected. Procedural errors were observed with ProTaper Universal Retreatment and Reciproc. © 2014 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Glassy carbon electrodes modified with multiwalled carbon nanotubes for the determination of ascorbic acid by square-wave voltammetry

Directory of Open Access Journals (Sweden)

Sushil Kumar

2012-05-01

Full Text Available Multiwalled carbon nanotubes were used to modify the surface of a glassy carbon electrode to enhance its electroactivity. Nafion served to immobilise the carbon nanotubes on the electrode surface. The modified electrode was used to develop an analytical method for the analysis of ascorbic acid (AA by square-wave voltammetry (SWV. The oxidation of ascorbic acid at the modified glassy carbon electrode showed a peak potential at 315 mV, about 80 mV lower than that observed at the bare (unmodified electrode. The peak current was about threefold higher than the response at the bare electrode. Replicate measurements of peak currents showed good precision (3% rsd. Peak currents increased with increasing ascorbic acid concentration (dynamic range = 0.0047–5.0 mmol/L and displayed good linearity (R2 = 0.994. The limit of detection was 1.4 μmol/L AA, while the limit of quantitation was 4.7 μmol/L AA. The modified electrode was applied to the determination of the amount of ascorbic acid in four brands of commercial orange-juice products. The measured content agreed well (96–104% with the product label claim for all brands tested. Recovery tests on spiked samples of orange juice showed good recovery (99–104%. The reliability of the SWV method was validated by conducting parallel experiments based on high-performance liquid chromatography (HPLC with absorbance detection. The observed mean AA contents of the commercial orange juice samples obtained by the two methods were compared statistically and were found to have no significant difference (P = 0.05.

Do Wellness Tourists Get Well? An Observational Study of Multiple Dimensions of Health and Well-Being After a Week-Long Retreat.

Science.gov (United States)

Cohen, Marc M; Elliott, Fiona; Oates, Liza; Schembri, Adrian; Mantri, Nitin

2017-02-01

Wellness retreats use many complementary and alternative therapies within a holistic residential setting, yet few studies have evaluated the effect of retreat experiences on multiple dimensions of health and well-being, and no published studies have reported health outcomes in wellness tourists. To assess the effect of a week-long wellness-retreat experience in wellness tourists. A longitudinal observational study with outcomes assessed upon arrival and departure and 6 weeks after the retreat. A rural health retreat in Queensland, Australia. A holistic, 1-week, residential, retreat experience that included many educational, therapeutic, and leisure activities and an organic, mostly plant-based diet. Multiple outcome measures were performed upon arrival and departure and 6 weeks after the retreat. These included anthropometric measures, urinary pesticide metabolites, a food and health symptom questionnaire, the Five Factor Wellness Inventory, the General Self Efficacy questionnaire, the Pittsburgh Insomnia Rating Scale, the Depression Anxiety Stress Scale, the Profile of Mood States, and the Cogstate cognitive function test battery. Statistically significant improvements (p effects and assess the value and relevance of retreat experiences to clinicians and health insurers.

Spontaneous arylation of activated carbon from aminobenzene organic acids as source of diazonium ions in mild conditions

International Nuclear Information System (INIS)

Lebègue, Estelle; Brousse, Thierry; Gaubicher, Joël; Cougnon, Charles

2013-01-01

Activated carbon products modified with benzoic, benzenesulfonic and benzylphosphonic acid groups were prepared by spontaneous reduction of aryldiazonium ions in situ generated in water from the corresponding aminobenzene organic acids without addition of an external acid. Electrochemistry and NMR studies show that the advancement of the diazotization reaction depends both on the acidity and the electronic effect of the organic acid substituent, giving a mixture of diazonium, amine and triazene functionalities. Carbon products prepared by reaction of activated carbon Norit with 4-aminobenzenecarboxylic acid, 4-aminobenzenesulfonic acid and (4-aminobenzyl)phosphonic acid were analyzed by chemical elemental analysis and X-ray photoelectron spectroscopy experiments. Results show that this strategy is well suited for the chemical functionalization, giving a maximized grafting yield due to a chemical cooperation of amine and diazonium functionalities

Nanofiltration and granular activated carbon treatment of perfluoroalkyl acids.

Science.gov (United States)

Appleman, Timothy D; Dickenson, Eric R V; Bellona, Christopher; Higgins, Christopher P

2013-09-15

Perfluoroalkyl acids (PFAAs) are of concern because of their persistence in the environment and the potential toxicological effects on humans exposed to PFAAs through a variety of possible exposure routes, including contaminated drinking water. This study evaluated the efficacy of nanofiltration (NF) and granular activated carbon (GAC) adsorption in removing a suite of PFAAs from water. Virgin flat-sheet NF membranes (NF270, Dow/Filmtec) were tested at permeate fluxes of 17-75 Lm(-2)h(-1) using deionized (DI) water and artificial groundwater. The effects of membrane fouling by humic acid on PFAA rejection were also tested under constant permeate flux conditions. Both virgin and fouled NF270 membranes demonstrated >93% removal for all PFAAs under all conditions tested. GAC efficacy was tested using rapid small-scale columns packed with Calgon Filtrasorb300 (F300) carbon and DI water with and without dissolved organic matter (DOM). DOM effects were also evaluated with F600 and Siemens AquaCarb1240C. The F300 GAC had 20% breakthrough of all PFAAs by 10,000 BVs was observed for all carbons. Copyright © 2013 Elsevier B.V. All rights reserved.

Electrocatalytic and simultaneous determination of isoproterenol, uric acid and folic acid at molybdenum (VI) complex-carbon nanotube paste electrode

International Nuclear Information System (INIS)

Beitollahi, Hadi; Sheikhshoaie, Iran

2011-01-01

Highlights: → A molybdenum (VI) complex-carbon nanotube paste electrode have been fabricated. → This electrode reduced the oxidation potential of isoproterenol by about 175 mV. → It resolved the voltammetric waves of isoproterenol, uric acid and folic acid. - Abstract: This paper describes the development, electrochemical characterization and utilization of a novel modified molybdenum (VI) complex-carbon nanotube paste electrode for the electrocatalytic determination of isoproterenol (IP). The electrochemical profile of the proposed modified electrode was analyzed by cyclic voltammetry (CV) that showed a shift of the oxidation peak potential of IP at 175 mV to less positive value, compared with an unmodified carbon paste electrode. Differential pulse voltammetry (DPV) in 0.1 M phosphate buffer solution (PBS) at pH 7.0 was performed to determine IP in the range from 0.7 to 600.0 μM, with a detection limit of 35.0 nM. Then the modified electrode was used to determine IP in an excess of uric acid (UA) and folic acid (FA) by DPV. Finally, this method was used for the determination of IP in some real samples.

The effect of carbon and nitrogen sources on the fatty acids profile of Mortierella vinacea

Directory of Open Access Journals (Sweden)

Mina Mohammadi Nasr

2017-01-01

Full Text Available Introduction: Microbial lipids attract attention of many researchers due to their therapeutic effects. The goal of this study is the production and optimization of lipids and fatty acids in Mortierella vinaceaby applying different media to achieve invaluable fatty acids in pharmaceutical and food industry. Materials and methods: Mortierella vinacea was cultured on potato dextrose agar. Then the spores were inoculated to the production medium. After 72 hours, the lipids were extracted and they were analyzedby gas chromatography. To optimize lipid and important fatty acids production in medium, various carbon and nitrogen sources were substituted with glucose and yeast extract respectively. Results: The effect of some carbon and nitrogen sources on biomass, lipid and fatty acids production were assayed. The highest level of lipid production was in a medium which contains lactose and yeast extract (26.66%. Linoleic acid was only produced in presence of lactose and yeast extract (25.7%. While, M. vinacea yielded the highest level of linoleic acid (52.76% in a medium containing peptone, linolenic acid was achieved only in presence of lactose and triptone. Discussion and conclusion: In this study, lactose as a carbon source was the most effective one in the production of lipids. In addition, linoleic acid was produced in presence of lactose, so lactose was selected as the best carbon source. Peptone and triptone as a nitrogen source were chosen for the production of linoleic acid and linolenic acid in M. vinacea respectively. All of these findings reveal that Mortierella strain is a potential candidate for enhancement of linoleic acid and linolenic acid production. Furthermore, this simple media can be used in production of linoleic acid and linolenic acid for industrial goals in large scales.

A glassy carbon electrode modified with a polyaniline doped with silicotungstic acid and carbon nanotubes for the sensitive amperometric determination of ascorbic acid

International Nuclear Information System (INIS)

Zhang, X.; Lai, G.; Zhang, H.; Yu, A.

2013-01-01

We report on an electrochemical sensor for the sensitive amperometric determination of ascorbic acid (AA). Aniline containing suspended silicotungstic acid and carbon nanotubes was electropolymerized on the surface of a glassy carbon electrode in a single step which provides a simple and controllable method and greatly improves the electrocatalytic oxidation of AA. The effects of scan rate, solution pH and working potential were studied. A linear relationship exists between the current measured and the concentration of AA in the range from 1 μM to 10 μM and 0.01 mM to 9 mM, with a limit of detection as low as 0.51 μM (S/N = 3). The sensor is selective, stable and satisfyingly reliable in real sample experiments. In our eyes, it has a large potential for practical applications. (author)

Carbon isotopic patterns of amino acids associated with various microbial metabolic pathways and physiological conditions

Science.gov (United States)

Wang, P. L.; Hsiao, K. T.; Lin, L. H.

2017-12-01

Amino acids represent one of the most important categories of biomolecule. Their abundance and isotopic patterns have been broadly used to address issues related to biochemical processes and elemental cycling in natural environments. Previous studies have shown that various carbon assimilative pathways of microorganisms (e.g. autotrophy, heterotrophy and acetotrophy) could be distinguished by carbon isotopic patterns of amino acids. However, the taxonomic and catabolic coverage are limited in previous examination. This study aims to uncover the carbon isotopic patterns of amino acids for microorganisms remaining uncharacterized but bearing biogeochemical and ecological significance in anoxic environments. To fulfill the purpose, two anaerobic strains were isolated from riverine wetland and mud volcano in Taiwan. One strain is a sulfate reducing bacterium (related to Desulfovibrio marrakechensis), which is capable of utilizing either H2 or lactate, and the other is a methanogen (related to Methanolobus profundi), which grows solely with methyl-group compounds. Carbon isotope analyses of amino acids were performed on cells grown in exponential and stationary phase. The isotopic patterns were similar for all examined cultures, showing successive 13C depletion along synthetic pathways. No significant difference was observed for the methanogen and lactate-utilizing sulfate reducer harvested in exponential and stationary phases. In contrast, the H2-utilizing sulfate reducer harvested in stationary phase depleted and enriched 13C in aspartic acid and glycine, respectively when compared with that harvested in exponential phase. Such variations might infer the change of carbon flux during synthesis of these two amino acids in the reverse TCA cycle. In addition, the discriminant function analysis for all available data from culture studies further attests the capability of using carbon isotope patterns of amino acids in identifying microbial metabolisms.

Psychological Effects of a 1-Month Meditation Retreat on Experienced Meditators: The Role of Non-attachment.

Science.gov (United States)

Montero-Marin, Jesus; Puebla-Guedea, Marta; Herrera-Mercadal, Paola; Cebolla, Ausias; Soler, Joaquim; Demarzo, Marcelo; Vazquez, Carmelo; Rodríguez-Bornaetxea, Fernando; García-Campayo, Javier

2016-01-01

Background: There are few studies devoted to assessing the impact of meditation-intensive retreats on the well-being, positive psychology, and personality of experienced meditators. We aimed to assess whether a 1-month Vipassana retreat: (a) would increase mindfulness and well-being; (b) would increase prosocial personality traits; and (c) whether psychological changes would be mediated and/or moderated by non-attachment. Method: A controlled, non-randomized, pre-post-intervention trial was used. The intervention group was a convenience sample ( n = 19) of experienced meditators who participated in a 1-month Vipassana meditation retreat. The control group ( n = 19) comprised matched experienced meditators who did not take part in the retreat. During the retreat, the mean duration of daily practice was 8-9 h, the diet was vegetarian and silence was compulsory. The Experiences Questionnaire (EQ), Non-attachment Scale (NAS), Positive and Negative Affect Schedule (PANAS), Satisfaction With Life Scale (SWLS), Temperament Character Inventory Revised (TCI-R-67), Five Facets Mindfulness Questionnaire (FFMQ), Self-Other Four Immeasurables (SOFI) and the MINDSENS Composite Index were administered. ANCOVAs and linear regression models were used to assess pre-post changes and mediation/moderation effects. Results: Compared to controls, retreatants showed increases in non-attachment, observing, MINDSENS, positive-affect, balance-affect, and cooperativeness; and decreases in describing, negative-others, reward-dependence and self-directedness. Non-attachment had a mediating role in decentring, acting aware, non-reactivity, negative-affect, balance-affect and self-directedness; and a moderating role in describing and positive others, with both mediating and moderating effects on satisfaction with life. Conclusions: A 1-month Vipassana meditation retreat seems to yield improvements in mindfulness, well-being, and personality, even in experienced meditators. Non-attachment might

Computational and experimental studies of the interaction between single-walled carbon nanotubes and folic acid

DEFF Research Database (Denmark)

Castillo, John J.; Rozo, Ciro E.; Castillo-León, Jaime

2013-01-01

Nlayered Integrated Molecular Orbital and Molecular Mechanics (B3LYP(6–31G(d):UFF)). The results confirmed that the interaction occurred via hydrogen bonding between protons of the glutamic moiety from folic acid and π electrons from the carbon nanotubes. The single-walled carbon nanotube-folic acid...

Carbon Isotopic Ratios of Amino Acids in Stardust-Returned Samples

Science.gov (United States)

Elsila, Jamie E.; Glavin, Daniel P.; Dworkin, Jason P.

2009-01-01

NASA's Stardust spacecraft returned to Earth samples from comet 81P/Wild 2 in January 2006. Preliminary examinations revealed the presence of a suite of organic compounds including several amines and amino acids, but the origin of these compounds could not be identified. Here. we present the carbon isotopic ratios of glycine and E-aminocaproic acid (EACH), the two most abundant amino acids observed, in Stardust-returned foil samples measured by gas chromatography-combustion-isotope ratio crass spectrometry coupled with quadrupole mass spectrometry (GC-QMS/IRMS).

Whole-body pharmacokinetics of HDAC inhibitor drugs, butyric acid, valproic acid and 4-phenylbutyric acid measured with carbon-11 labeled analogs by PET

International Nuclear Information System (INIS)

Kim, Sung Won; Hooker, Jacob M.; Otto, Nicola; Win, Khaing; Muench, Lisa; Shea, Colleen; Carter, Pauline; King, Payton; Reid, Alicia E.; Volkow, Nora D.; Fowler, Joanna S.

2013-01-01

The fatty acids, n-butyric acid (BA), 4-phenylbutyric acid (PBA) and valproic acid (VPA, 2-propylpentanoic acid) have been used for many years in the treatment of a variety of CNS and peripheral organ diseases including cancer. New information that these drugs alter epigenetic processes through their inhibition of histone deacetylases (HDACs) has renewed interest in their biodistribution and pharmacokinetics and the relationship of these properties to their therapeutic and side effect profiles. In order to determine the pharmacokinetics and biodistribution of these drugs in primates, we synthesized their carbon-11 labeled analogues and performed dynamic positron emission tomography (PET) in six female baboons over 90 min. The carbon-11 labeled carboxylic acids were prepared by using 11 CO 2 and the appropriate Grignard reagents. [ 11 C]BA was metabolized rapidly (only 20% of the total carbon-11 in plasma was parent compound at 5 min post injection) whereas for VPA and PBA 98% and 85% of the radioactivity were the unmetabolized compound at 30 min after their administration respectively. The brain uptake of all three carboxylic acids was very low ( VPA > PBA), which is consistent with the need for very high doses for therapeutic efficacy. Most of the radioactivity was excreted through the kidneys and accumulated in the bladder. However, the organ biodistribution between the drugs differed. [ 11 C]BA showed relatively high uptake in spleen and pancreas whereas [ 11 C]PBA showed high uptake in liver and heart. Notably, [ 11 C]VPA showed exceptionally high heart uptake possibly due to its involvement in lipid metabolism. The unique biodistribution of each of these drugs may be of relevance in understanding their therapeutic and side effect profile including their teratogenic effects

EFFICACY OF PROTAPER NEXT AND PROTAPER UNIVERSAL RETREATMENT SYSTEMS IN REMOVING GUTTA-PERCHA IN CURVED ROOT CANALS DURING ROOT CANAL RETREATMENT

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Taha ÖZYÜREK

2017-04-01

Full Text Available Purpose: The aim of this study was to compare the cleanliness of root canal walls after retreatment using ProTaper Next (PTN, ProTaper Universal Retreatment (PTR nickel-titanium (NiTi systems and Hedström hand files in curved mesial canals of mandibular molar teeth and the time required for gutta-percha and sealer removal. Materials and Methods: Ninety mandibular molar teeth with curved mesial roots were instrumented up to #35.04 with Mtwo NiTi rotary instruments and obturated using the continuous wave of condensation technique. Removal of gutta-percha and sealer was performed using one of the following: PTN and PTR NiTi systems and Hedström hand files. Samples were placed on the VistaScan phosphor plates in the mesio-distal direction and the radiographs were taken. The digital radiographs were analyzed using AutoCAD software. Also, the total time required for gutta-percha removal was calculated by a chronometer. Results: The total retreatment time was significantly shorter in the PTN and PTR groups compared with the manual group (p<0.05. There was a significant difference between the groups according to the total residual gutta-percha and sealer (p<0.05. The PTN and PTR groups left significantly less gutta-percha and sealer remnant than the manual group (p<0.001. Conclusion: Within the limitations of this study, the PTN and PTR groups showed less residual gutta-percha and sealer than the manual group. The NiTi rotary systems were significantly faster than the manual group in the time required for gutta-percha and sealer removal.

Feasibility study on application of volume acid fracturing technology to tight gas carbonate reservoir development

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Nianyin Li

2015-09-01

Full Text Available How to effectively develop tight-gas carbonate reservoir and achieve high recovery is always a problem for the oil and gas industry. To solve this problem, domestic petroleum engineers use the combination of the successful experiences of North American shale gas pools development by stimulated reservoir volume (SRV fracturing with the research achievements of Chinese tight gas development by acid fracturing to propose volume acid fracturing technology for fractured tight-gas carbonate reservoir, which has achieved a good stimulation effect in the pilot tests. To determine what reservoir conditions are suitable to carry out volume acid fracturing, this paper firstly introduces volume acid fracturing technology by giving the stimulation mechanism and technical ideas, and initially analyzes the feasibility by the comparison of reservoir characteristics of shale gas with tight-gas carbonate. Then, this paper analyzes the validity and limitation of the volume acid fracturing technology via the analyses of control conditions for volume acid fracturing in reservoir fracturing performance, natural fracture, horizontal principal stress difference, orientation of in-situ stress and natural fracture, and gives the solution for the limitation. The study results show that the volume acid fracturing process can be used to greatly improve the flow environment of tight-gas carbonate reservoir and increase production; the incremental or stimulation response is closely related with reservoir fracturing performance, the degree of development of natural fracture, the small intersection angle between hydraulic fracture and natural fracture, the large horizontal principal stress difference is easy to form a narrow fracture zone, and it is disadvantageous to create fracture network, but the degradable fiber diversion technology may largely weaken the disadvantage. The practices indicate that the application of volume acid fracturing process to the tight-gas carbonate

Efficacy and safety of bortezomib-based retreatment at the first relapse in multiple myeloma patients: A retrospective study.

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Oriol, Albert; Giraldo, Pilar; Kotsianidis, Ioannis; Couturier, Catherine; Olie, Robert; Angermund, Ralf; Corso, Alessandro

2015-08-01

Multiple myeloma remains incurable and retreatment with available therapies is of substantial interest. This retrospective observational study included data from 35 patients treated initially and at the first relapse with bortezomib-containing regimens. Bortezomib retreatment provided a similar depth and time to response as first-line therapy; however, as could be expected, the duration of response was shorter with retreatment. The tolerability profile was similar with bortezomib as the first- and second-line therapy, with no evidence of cumulative toxicity. These findings support bortezomib retreatment after a treatment-free interval of ≥6 months in patients who achieved at least a partial response to the first-line bortezomib-based therapy.

Habitat selection in a rocky landscape: experimentally decoupling the influence of retreat site attributes from that of landscape features.

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Benjamin M Croak

Full Text Available Organisms selecting retreat sites may evaluate not only the quality of the specific shelter, but also the proximity of that site to resources in the surrounding area. Distinguishing between habitat selection at these two spatial scales is complicated by co-variation among microhabitat factors (i.e., the attributes of individual retreat sites often correlate with their proximity to landscape features. Disentangling this co-variation may facilitate the restoration or conservation of threatened systems. To experimentally examine the role of landscape attributes in determining retreat-site quality for saxicolous ectotherms, we deployed 198 identical artificial rocks in open (sun-exposed sites on sandstone outcrops in southeastern Australia, and recorded faunal usage of those retreat sites over the next 29 months. Several landscape-scale attributes were associated with occupancy of experimental rocks, but different features were important for different species. For example, endangered broad-headed snakes (Hoplocephalus bungaroides preferred retreat sites close to cliff edges, flat rock spiders (Hemicloea major preferred small outcrops, and velvet geckos (Oedura lesueurii preferred rocks close to the cliff edge with higher-than-average sun exposure. Standardized retreat sites can provide robust experimental data on the effects of landscape-scale attributes on retreat site selection, revealing interspecific divergences among sympatric taxa that use similar habitats.

Synthesis of sulfonated porous carbon nanospheres solid acid by a facile chemical activation route

Energy Technology Data Exchange (ETDEWEB)

Chang, Binbin, E-mail: changbinbin806@163.com; Guo, Yanzhen; Yin, Hang; Zhang, Shouren; Yang, Baocheng, E-mail: baochengyang@yahoo.com

2015-01-15

Generally, porous carbon nanospheres materials are usually prepared via a template method, which is a multi-steps and high-cost strategy. Here, we reported a porous carbon nanosphere solid acid with high surface area and superior porosity, as well as uniform nanospheical morphology, which prepared by a facile chemical activation with ZnCl{sub 2} using resorcinol-formaldehyde (RF) resins spheres as precursor. The activation of RF resins spheres by ZnCl{sub 2} at 400 °C brought high surface area and large volume, and simultaneously retained numerous oxygen-containing and hydrogen-containing groups due to the relatively low processing temperature. The presence of these functional groups is favorable for the modification of –SO{sub 3}H groups by a followed sulfonation treating with sulphuric acid and organic sulfonic acid. The results of N{sub 2} adsorption–desorption and electron microscopy clearly showed the preservation of porous structure and nanospherical morphology. Infrared spectra certified the variation of surface functional groups after activation and the successful modification of –SO{sub 3}H groups after sulfonation. The acidities of catalysts were estimated by an indirect titration method and the modified amount of –SO{sub 3}H groups were examined by energy dispersive spectra. The results suggested sulfonated porous carbon nanospheres catalysts possessed high acidities and –SO{sub 3}H densities, which endowed their significantly catalytic activities for biodiesel production. Furthermore, their excellent stability and recycling property were also demonstrated by five consecutive cycles. - Graphical abstract: Sulfonated porous carbon nanospheres with high surface area and superior catalytic performance were prepared by a facile chemical activation route. - Highlights: • Porous carbon spheres solid acid prepared by a facile chemical activation. • It owns high surface area, superior porosity and uniform spherical morphology. • It possesses

Adsorption mechanism of 2,4-dichlorophenoxyacetic acid onto nitric-acid-modified activated carbon fiber.

Science.gov (United States)

Li, Qun; Sun, Jie; Ren, Tianhao; Guo, Lin; Yang, Zhilin; Yang, Qi; Chen, Hai

2018-04-01

Adsorption by carbon materials is one of the relatively fast methods in present research, which is widely used in emergency events. Activated carbon fiber (ACF) modified by nitric acid (N-ACF) was studied in this research to determine the adsorption performance for 2,4-dichlorophenoxyacetic acid (2,4-D). Subsequently, influence factors, adsorption isotherm models, kinetics and thermodynamic were investigated in a batch system to realize this adsorption. Experimental results showed that ACF modified by 0.1M nitric acid had a better removal ability than 2,4-D. Removal rate of 2,4-D by N-ACF was greatly influenced by pH with the optimum pH at 2. The superiority of the Langmuir isotherm model in describing the adsorption equilibrium was revealed by correlation coefficients R2 (R 2  ≥ 0.997). Furthermore, adsorption kinetics was well described by pseudo-second-order model. The results of thermodynamic showed that adsorption was a spontaneous, endothermic process with randomness increasing. Additionally, surface structure properties of adsorbent were characterized by Scanning electron microscopy, Fourier transform infrared spectroscopy, Specific surface area analysis of Brunauer, Emmett and Teller and Boehm's titration. It turned out that the micropore structure and functional groups on N-ACF all can contribute to the removal of 2,4-D.

Physicochemical properties of carbons prepared from pecan shell by phosphoric acid activation.

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Guo, Yanping; Rockstraw, David A

2007-05-01

Activated carbons were prepared from pecan shell by phosphoric acid activation. The pore structure and acidic surface groups of these carbons were characterized by nitrogen adsorption, Boehm titration and transmittance Fourier infrared spectroscopy (FTIR) techniques. The characterization results demonstrated that the development of pore structure was apparent at temperatures 250 degrees C, and reached 1130m(2)/g and 0.34cm(3)/g, respectively, at 500 degrees C. Impregnation ratio and soaking time at activation temperature also affected the pore development and pore size distribution of final carbon products. At an impregnation ratio of 1.5, activated carbon with BET surface area and micropore volume as high as 861m(2)/g and 0.289cm(3)/g was obtained at 400 degrees C. Microporous activated carbons were obtained in this study. Low impregnation ratio (less than 1.5) and activation temperature (less than 300 degrees C) are favorable to the formation of acidic surface functional groups, which consist of temperature-sensitive (unstable at high temperature) and temperature-insensitive (stable at high temperature) two parts. The disappearance of temperature-sensitive groups was significant at temperature 300 degrees C; while the temperature-insensitive groups are stable even at 500 degrees C. FTIR results showed that the temperature-insensitive part was mostly phosphorus-containing groups as well as some carbonyl-containing groups, while carbonyl-containing groups were the main contributor of temperature-sensitive part.

The antimicrobial effectiveness of photodynamic therapy used as an addition to the conventional endodontic re-treatment: a clinical study.

Science.gov (United States)

Jurič, Ivona Bago; Plečko, Vanda; Pandurić, Dragana Gabrić; Anić, Ivica

2014-12-01

The purpose of the study was to evaluate the efficacy of antimicrobial photodynamic therapy (aPDT) used as an adjunct to the endodontic re-treatment in the eradication of microorganisms from previously filled root canals. The study sample consisted of 21 randomly selected patients with root filled and infected root canal system with chronic apical periodontitis on incisors or canines, who have had previously endodontic treatment. Microbiological samples from the root canals were collected after accessing the canal, following the endodontic re-treatment and after the aPDT procedure. During instrumentation, the root canals were irrigated with 2.5% sodium hypochlorite (NaOCl), and the final irrigation protocol included 17% ethylenediaminetetraacetic acid followed by NaOCl. Root canals were filled with a phenothiazinium chloride and irradiated with a diode laser (λ=660 nm, 100 mW) for 1 min. Microbiological samples from the root canals were cultivated on selective plates, and the identification was done by micromorphology, macromorphology and different API strips as well as bacterial counts (colony forming units). Fourteen bacteria species were isolated from the root canals initially, with a mean value of 4.57 species per canal. Although endodontic re-treatment alone produced a significant reduction in the number of bacteria species (pendodontic treatment and aPDT was statistically more effective (proot canals of 11 teeth. The results indicated that the aPDT used as an adjunct to the conventional endodontic therapy achieved a significant further reduction of intracanal microbial load. Copyright © 2014 Elsevier B.V. All rights reserved.

Modeling and optimizing the design of matrix treatments in carbonate reservoirs with self-diverting acid systems

International Nuclear Information System (INIS)

Bulgakova, G T; Kharisov, R Ya; Sharifullin, A R; Pestrikov, A V

2015-01-01

Application of a self-diverting-acid based on viscoelastic surfactant (SDVA) is a promising technology for improving the efficacy of acid treatment in oil and gas-bearing carbonate reservoirs. In this study, we present a mathematical model for assessing SDVA flow and reaction with carbonate rock using the SDVA rheological characteristics. The model calculates the technological parameters for acidizing operations and the prediction of well productivity after acid treatment, in addition to technical and economic optimization of the acidizing process by modeling different acid treatment options with varying volumes, injection rates, process fluids stages and initial economic scenarios

A comparative evaluation of efficacy of protaper universal rotary retreatment system for gutta-percha removal with or without a solvent.

Science.gov (United States)

Kumar, M Sita Ram; Sajjan, Girija S; Satish, Kalyan; Varma, K Madhu

2012-09-01

The aim was to evaluate and compare the efficacy of ProTaper Universal rotary retreatment system with or without solvent and stainless steel hand files for endodontic filling removal from root canals and also to compare retreatment time for each system. Thirty extracted mandibular premolars with single straight canals were endodontically treated. Teeth were divided into three major groups, having 10 specimens each. Removal of obturating material in group 1 by stainless steel hand files with RC Solve, group 2 by ProTaper Universal retreatment instruments and group 3 by ProTaper Universal retreatment instruments along with RC solve was done. Retreatment was considered complete for all groups when no filling material was observed on the instruments. The retreatment time was recorded for each tooth. All specimens were grooved longitudinally in a buccolingual direction. The split halves were examined under a stereomicroscope and images were captured and analyzed. The remaining filling debris area ratios were considered for statistical analysis. With ANOVA test, statistical analysis showed that there was statistically no significant difference regarding the amount of filling remnants between the groups (P ProTaper Universal retreatment system files alone proved to be faster than the other experimental groups.

Carbon magnetic resonance spectroscopy on carbon-13-labeled uracil in 5S ribonucleic acid

International Nuclear Information System (INIS)

Hamill, W.D.; Grant, D.M.; Cooper, R.B.; Harmon, S.A.

1978-01-01

The carbon-13 nuclear magnetic resonance spectra of the 13 C-enriched C-4 uridine carbons in 5S ribosomal ribonucleic acid of Salmonella typhimurium, strain JL-1055, was obtained. The most striking feature of the 5S RNA spectrum was the large number of well-resolved lines in the uridine band covering a chemical shift range of approximately 3.6 ppM. This data was used to obtain information on the secondary structure. The number of uridines involved in secondary interactions is estimated to be at least 75% and may be as high as 95%

Extracorporeal Carbon Dioxide Removal Enhanced by Lactic Acid Infusion in Spontaneously Breathing Conscious Sheep.

Science.gov (United States)

Scaravilli, Vittorio; Kreyer, Stefan; Belenkiy, Slava; Linden, Katharina; Zanella, Alberto; Li, Yansong; Dubick, Michael A; Cancio, Leopoldo C; Pesenti, Antonio; Batchinsky, Andriy I

2016-03-01

The authors studied the effects on membrane lung carbon dioxide extraction (VCO2ML), spontaneous ventilation, and energy expenditure (EE) of an innovative extracorporeal carbon dioxide removal (ECCO2R) technique enhanced by acidification (acid load carbon dioxide removal [ALCO2R]) via lactic acid. Six spontaneously breathing healthy ewes were connected to an extracorporeal circuit with blood flow 250 ml/min and gas flow 10 l/min. Sheep underwent two randomly ordered experimental sequences, each consisting of two 12-h alternating phases of ALCO2R and ECCO2R. During ALCO2R, lactic acid (1.5 mEq/min) was infused before the membrane lung. Caloric intake was not controlled, and animals were freely fed. VCO2ML, natural lung carbon dioxide extraction, total carbon dioxide production, and minute ventilation were recorded. Oxygen consumption and EE were calculated. ALCO2R enhanced VCO2ML by 48% relative to ECCO2R (55.3 ± 3.1 vs. 37.2 ± 3.2 ml/min; P less than 0.001). During ALCO2R, minute ventilation and natural lung carbon dioxide extraction were not affected (7.88 ± 2.00 vs. 7.51 ± 1.89 l/min, P = 0.146; 167.9 ± 41.6 vs. 159.6 ± 51.8 ml/min, P = 0.063), whereas total carbon dioxide production, oxygen consumption, and EE rose by 12% each (223.53 ± 42.68 vs. 196.64 ± 50.92 ml/min, 215.3 ± 96.9 vs. 189.1 ± 89.0 ml/min, 67.5 ± 24.0 vs. 60.3 ± 20.1 kcal/h; P less than 0.001). ALCO2R was effective in enhancing VCO2ML. However, lactic acid caused a rise in EE that made ALCO2R no different from standard ECCO2R with respect to ventilation. The authors suggest coupling lactic acid-enhanced ALCO2R with active measures to control metabolism.

Graphitic carbon nitride nanosheets doped graphene oxide for electrochemical simultaneous determination of ascorbic acid, dopamine and uric acid

International Nuclear Information System (INIS)

Zhang, Hanqiang; Huang, Qitong; Huang, Yihong; Li, Feiming; Zhang, Wuxiang; Wei, Chan; Chen, Jianhua; Dai, Pingwang; Huang, Lizhang; Huang, Zhouyi; Kang, Lianping; Hu, Shirong; Hao, Aiyou

2014-01-01

Graphical abstract: Schematic drawing of electrochemical oxidize AA, DA and UA on graphitic carbon nitride nanosheets-graphene oxide composite modified electrode. - Highlights: • Synthesize g-C 3 N 4 , GO and CNNS-GO composite. • CNNS-GO composite was the first time for simultaneous determination of AA, DA and UA. • CNNS-GO/GCE displays fantastic selectivity and sensitivity for AA, DA and UA. • CNNS-GO/GCE was applied to detect real sample with satisfactory results. - Abstract: Graphitic carbon nitride nanosheets with a graphite-like structure have strong covalent bonds between carbon and nitride atoms, and nitrogen atoms in the carbon architecture can accelerate the electron transfer and enhance electrical properties effectually. The graphitic carbon nitride nanosheets-graphene oxide composite was synthesized. And the electrochemical performance of the composite was investigated by cyclic voltammetry and differential pulse voltammetry ulteriorly. Due to the synergistic effects of layer-by-layer structures by π-π stacking or charge-transfer interactions, graphitic carbon nitride nanosheets-graphene oxide composite can improved conductivity, electro-catalytic and selective oxidation performance. The proposed graphitic carbon nitride nanosheets-graphene oxide composite modified electrode was employed for simultaneous determination of ascorbic acid, dopamine and uric acid in their mixture solution, it exhibited distinguished sensitivity, wide linear range and low detection limit. Moreover, the modified electrode was applied to detect urine and dopamine injection sample, and then the samples were spiked with certain concentration of three substances with satisfactory recovery results

Reconceptualizing Leadership in Migrant Communities: Latina/o Parent Leadership Retreats as Sites of Community Cultural Wealth

Science.gov (United States)

Nava, Pedro E.; Lara, Argelia

2016-01-01

This article examines how the Education Leadership Foundation (a leadership development community based organization) in partnership with the Migrant Education Program use parent retreats for building leadership, and skill development of migrant farm-working families. Utilizing cooperative and community responsive practices, these retreats build…

End of the Little Ice Age in the Alps forced by industrial black carbon.

Science.gov (United States)

Painter, Thomas H; Flanner, Mark G; Kaser, Georg; Marzeion, Ben; VanCuren, Richard A; Abdalati, Waleed

2013-09-17

Glaciers in the European Alps began to retreat abruptly from their mid-19th century maximum, marking what appeared to be the end of the Little Ice Age. Alpine temperature and precipitation records suggest that glaciers should instead have continued to grow until circa 1910. Radiative forcing by increasing deposition of industrial black carbon to snow may represent the driver of the abrupt glacier retreats in the Alps that began in the mid-19th century. Ice cores indicate that black carbon concentrations increased abruptly in the mid-19th century and largely continued to increase into the 20th century, consistent with known increases in black carbon emissions from the industrialization of Western Europe. Inferred annual surface radiative forcings increased stepwise to 13-17 W⋅m(-2) between 1850 and 1880, and to 9-22 W⋅m(-2) in the early 1900s, with snowmelt season (April/May/June) forcings reaching greater than 35 W⋅m(-2) by the early 1900s. These snowmelt season radiative forcings would have resulted in additional annual snow melting of as much as 0.9 m water equivalent across the melt season. Simulations of glacier mass balances with radiative forcing-equivalent changes in atmospheric temperatures result in conservative estimates of accumulating negative mass balances of magnitude -15 m water equivalent by 1900 and -30 m water equivalent by 1930, magnitudes and timing consistent with the observed retreat. These results suggest a possible physical explanation for the abrupt retreat of glaciers in the Alps in the mid-19th century that is consistent with existing temperature and precipitation records and reconstructions.

Effect of Topography on Subglacial Discharge and Submarine Melting During Tidewater Glacier Retreat

Science.gov (United States)

Amundson, J. M.; Carroll, D.

2018-01-01

To first order, subglacial discharge depends on climate, which determines precipitation fluxes and glacier mass balance, and the rate of glacier volume change. For tidewater glaciers, large and rapid changes in glacier volume can occur independent of climate change due to strong glacier dynamic feedbacks. Using an idealized tidewater glacier model, we show that these feedbacks produce secular variations in subglacial discharge that are influenced by subglacial topography. Retreat along retrograde bed slopes (into deep water) results in rapid surface lowering and coincident increases in subglacial discharge. Consequently, submarine melting of glacier termini, which depends on subglacial discharge and ocean thermal forcing, also increases during retreat into deep water. Both subglacial discharge and submarine melting subsequently decrease as glacier termini retreat out of deep water and approach new steady state equilibria. In our simulations, subglacial discharge reached peaks that were 6-17% higher than preretreat values, with the highest values occurring during retreat from narrow sills, and submarine melting increased by 14% for unstratified fjords and 51% for highly stratified fjords. Our results therefore indicate that submarine melting acts in concert with iceberg calving to cause tidewater glacier termini to be unstable on retrograde beds. The full impact of submarine melting on tidewater glacier stability remains uncertain, however, due to poor understanding of the coupling between submarine melting and iceberg calving.

Overall response rates to radiation therapy for patients with painful uncomplicated bone metastases undergoing initial treatment and retreatment

International Nuclear Information System (INIS)

Bedard, Gillian; Hoskin, Peter; Chow, Edward

2014-01-01

Introduction: Radiation therapy has been shown to successfully palliate bone metastases. A number of systematic reviews and large clinical trials have reported response rates for initial treatment and retreatment. Objective: To determine overall response rates of patients with painful uncomplicated bone metastases undergoing initial treatment and retreatment. Methods: Intent-to-treat and evaluable patient statistics from a systematic review of palliative radiotherapy trials for initial treatment of bone metastases and a randomized clinical trial of retreatment were pooled and analyzed to determine the overall response rates for patients receiving initial treatment and retreatment. Results: In the intent-to-treat calculation, 71–73% of patients had an overall response to radiation treatment and in the evaluable patient population; 85–87% of patients did so. Response rates varied slightly whether patients underwent single or multiple fractions in initial treatment or retreatment. Conclusions: Single and multiple fraction radiation treatment yielded very similar overall response rates. Patients treated with a single fraction for both initial and repeat radiation experience almost identical overall response to those patients treated with multiple fraction treatment. It is therefore recommended that patients with uncomplicated painful bone metastases be treated with a single 8 Gy fraction of radiation at both the initial treatment and retreatment

Studies of the pH dependence of 13C shifts and carbon-carbon coupling constants of [U-13C]aspartic and -glutamic acids

International Nuclear Information System (INIS)

London, R.E.; Walker, T.E.; Kollman, V.H.; Matwiyoff, N.A.

1978-01-01

13 C NMR studies of the chemical shifts and carbon--carbon spin--spin coupling constants of 90% [U- 13 C]aspartic and -glutamic acids are reported. Effects of titration of the two carboxyl groups are separated computationally and the results compared with those for asparagine and glutamine, aspartate and glutamate containing peptides, and a series of amino-n-butyric acids. The results indicate that the carboxyl carbon shift resulting from titration of the carboxyl group is strongly dependent on its distance (number of bonds) from an amino group. Alternatively, remote methyl groups exhibit a much smaller titration induced shift than carboxyl groups in the corresponding position. Significant remote effects of pH titration on the one-bond carbon-carbon coupling are also observed, particularly for couplings involving the side-chain carboxyl carbons. These results are discussed in terms of polarization of the C--O bonds in response to titration of a remote carboxyl group. Values of 3 J/sub CC/ in asparate and glutamate indicate a strong conformational dependence. Rotamer populations predicted on the basis of the observed couplings and theoretical INDO calculations are in good agreement with values based on analysis of the 3 J/sub HH/ and 3 J/sub CH/ couplings. For a given conformation of glutamic acid, it is found that 3 J 14 is considerably smaller than 3 J 25 . This result is consistent with obsrvations on a number of other 13 C-labeled amino acids. 5 figures, 4 tables

Carbon isotope effects in carbohydrates and amino acids of photosynthesizing organisms

International Nuclear Information System (INIS)

Ivlev, A.A.; Kaloshin, A.G.; Koroleva, M.Ya.

1982-01-01

The analysis of the carbon isotope distribution in carbohydrates and amino acids of some photosynthesizing organisms revealed the close relationship between distribution and the pathways of biosynthesis of the molecules. This relationship is explained on the basis of the previously proposed mechanism of carbon isotope fractionation in a cell, in which the chief part is played by kinetic isotope effects in the pyruvate decarboxylation reaction progressively increased in the conjugated processes of gluconeogenesis. Isotope differences of C 2 and C 3 fragments arising in decarboxylation of pyruvate, as well as isotope differences of biogenic acceptor and environmental CO 2 appearing in assimilation are the main reasons of the observed intramolecular isotopic heterogeneity of biomolecules. The heterogeneity is preserved in metabolites owing to an incomplete mixing of carbon atoms in biochemical reactions. The probable existence of two pools of carbohydrates in photosynthesizing organisms different in isotopic composition is predicted. Two types of intramolecular isotope distribution in amino acids are shown. (author)

Carbon isotope effects in carbohydrates and amino acids of photosynthesizing organisms

Energy Technology Data Exchange (ETDEWEB)

Ivlev, A.A.; Kaloshin, A.G.; Koroleva, M.Ya. (Ministerstvo Geologii SSR, Moscow)

1982-02-10

The analysis of the carbon isotope distribution in carbohydrates and amino acids of some photosynthesizing organisms revealed the close relationship between distribution and the pathways of biosynthesis of the molecules. This relationship is explained on the basis of the previously proposed mechanism of carbon isotope fractionation in a cell, in which the chief part is played by kinetic isotope effects in the pyruvate decarboxylation reaction progressively increased in the conjugated processes of gluconeogenesis. Isotope differences of C/sub 2/ and C/sub 3/ fragments arising in decarboxylation of pyruvate, as well as isotope differences of biogenic acceptor and environmental CO/sub 2/ appearing in assimilation are the main reasons of the observed intramolecular isotopic heterogeneity of biomolecules. The heterogeneity is preserved in metabolites owing to an incomplete mixing of carbon atoms in biochemical reactions. The probable existence of two pools of carbohydrates in photosynthesizing organisms different in isotopic composition is predicted. Two types of intramolecular isotope distribution in amino acids are shown.

Kinetics of dodecanoic acid adsorption from caustic solution by activated carbon.

Science.gov (United States)

Pendleton, Phillip; Wu, Sophie Hua

2003-10-15

This study examines the influences of adsorbent porosity and surface chemistry and of carbon dosage on dodecanoic acid adsorption kinetics from aqueous and 2 M NaOH solutions as batch adsorption processes. Both adsorbents are steam-activated carbons prepared from either coconut or coal precursors. Prior to use the adsorbents were washed in deionized water or 2 M NaOH. Mass transfer coefficients and effective overall diffusion coefficients indicate a minor contribution from adsorbent porosity. In contrast, high surface oxygen content impedes transport to and into the adsorbent structure. Carbon dosage shows a proportional increase in transport coefficients with increasing mass; these coefficients are constant when normalized per unit mass. Neither water nor NaOH treatment of the adsorbents has a significant influence on dodecanoic acid adsorption kinetics. Molecular and Knudsen diffusion coefficients are defined to demonstrate that the overall effective diffusion coefficient values and the diffusion process are controlled by surface diffusion.

Salt Marshes as Monitors of Late Holocene Outlet Glacier Retreat

Science.gov (United States)

Wake, L. M.; Woodroffe, S.; Long, A. J.; Milne, G. A.

2014-12-01

New proxy sea-level records extracted from salt marshes in the vicinity of Jakobshavn Isbrae (Pakitsoq; 69.51°N, 50.74°W) and at previous sites in central western Greenland (Sisimiut; 66.47°N, 53.61°W and Aasiaat; 68.69°N, 52.88°W) are analyzed with respect to their ability to act as proximal tide gauges detecting mass balance changes in nearby outlet glaciers associated with the transition from the Little Ice Age ("LIA", 1400-1850AD) to the Industrial Period (>1850AD). Data at Pakitsoq demonstrate that sea-level rose at a rate of 3.5 ±1.7 mm/yr prior to 1850AD and slowed to 0.3 ±0.6mm/yr thereafter, producing a slowdown in sea level of 3.2 ± 1.8 mm/yr. A similar slowdown, occurring at 1600AD, is observed at Aasiaat and Sisimiut. We interpret these observed changes using a glacial isostatic adjustment model of sea-level change truncated at degree and order 4096, with an aim to determine if the sea-level data can be used to place constraints on changes in Jakobshavn Isbrae and/or Kangiata Nunaata Sermia (Nuuk fjord) during this period. Modelled sea level at Pakitsoq is insensitive to the location of thickening (thinning) associated with grounding line advance (retreat) and the rate of advance and retreat but is sensitive to the change point in time between periods of growth associated with LIA expansion (sea level rise) and the onset of 19th century recession (sea level fall) of Jakobshavn Isbrae. We conclude that the change in sea-level rate observed at Pakitsoq circa 1850AD marks the onset of post LIA retreat of this outlet glacier. Conversely, the modelled sea-level response to the retreat of Kangiata Nunaata Sermia from its LIA maximum at ca. 1761AD is below the detection threshold of the salt marsh record at Sisimiut.

A comparative evaluation of efficacy of protaper universal rotary retreatment system for gutta-percha removal with or without a solvent

Directory of Open Access Journals (Sweden)

M Sita Ram Kumar

2012-01-01

Full Text Available Aim: The aim was to evaluate and compare the efficacy of ProTaper Universal rotary retreatment system with or without solvent and stainless steel hand files for endodontic filling removal from root canals and also to compare retreatment time for each system. Materials and Methods: Thirty extracted mandibular premolars with single straight canals were endodontically treated. Teeth were divided into three major groups, having 10 specimens each. Removal of obturating material in group 1 by stainless steel hand files with RC Solve, group 2 by ProTaper Universal retreatment instruments and group 3 by ProTaper Universal retreatment instruments along with RC solve was done. Retreatment was considered complete for all groups when no filling material was observed on the instruments. The retreatment time was recorded for each tooth. All specimens were grooved longitudinally in a buccolingual direction. The split halves were examined under a stereomicroscope and images were captured and analyzed. The remaining filling debris area ratios were considered for statistical analysis. Results: With ANOVA test, statistical analysis showed that there was statistically no significant difference regarding the amount of filling remnants between the groups (P < 0.05. Differences between the means of groups are statistically significant regarding the retreatment time. Conclusion: Irrespective of the technique used, all the specimens had some remnants on the root canal wall. ProTaper Universal retreatment system files alone proved to be faster than the other experimental groups.

Differences in the clinical-epidemiological profile between new cases of tuberculosis and retreatment cases after default

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Aylana de Souza Belchior

Full Text Available Abstract OBJECTIVE To identify the socioeconomic and clinical-epidemiological factors related to tuberculosis in new cases and retreatment cases. METHOD Comparative study with 126 patients, of which 42 were retreatment cases after default attended in a reference center, and 84 were new cases completing the first treatment and treated in Basic Health Units. The collection of primary data was through interview, and of secondary data by records of the Notifiable Diseases Information System. Comparative analysis between the two groups. RESULTS The new cases differ from retreatment cases regarding educational level. The clinical-epidemiological profile shows a significant difference in relation to performance of the tuberculin skin test, and the HIV test result (positive in favor of new cases. In relation to performance of sputum culture and the result (positive of the first sputum smear of the first and second samples, in favor of retreatment cases. CONCLUSION The two groups are significantly different in clinical and epidemiological characteristics that show the access to exams.

A model ensemble for projecting multi‐decadal coastal cliff retreat during the 21st century

Science.gov (United States)

Limber, Patrick; Barnard, Patrick; Vitousek, Sean; Erikson, Li

2018-01-01

Sea cliff retreat rates are expected to accelerate with rising sea levels during the 21st century. Here we develop an approach for a multi‐model ensemble that efficiently projects time‐averaged sea cliff retreat over multi‐decadal time scales and large (>50 km) spatial scales. The ensemble consists of five simple 1‐D models adapted from the literature that relate sea cliff retreat to wave impacts, sea level rise (SLR), historical cliff behavior, and cross‐shore profile geometry. Ensemble predictions are based on Monte Carlo simulations of each individual model, which account for the uncertainty of model parameters. The consensus of the individual models also weights uncertainty, such that uncertainty is greater when predictions from different models do not agree. A calibrated, but unvalidated, ensemble was applied to the 475 km‐long coastline of Southern California (USA), with 4 SLR scenarios of 0.5, 0.93, 1.5, and 2 m by 2100. Results suggest that future retreat rates could increase relative to mean historical rates by more than two‐fold for the higher SLR scenarios, causing an average total land loss of 19 – 41 m by 2100. However, model uncertainty ranges from +/‐ 5 – 15 m, reflecting the inherent difficulties of projecting cliff retreat over multiple decades. To enhance ensemble performance, future work could include weighting each model by its skill in matching observations in different morphological settings

Comparison of the amount of apically extruded debris produced by four retreatment techniques: an ex vivo study

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Cristiane Ferreira Alfenas

2017-12-01

Full Text Available Objective: the aim of this study was to compare the amount of apically extruded debris during the removal of root canal filling material using nickel-titanium rotary retreatment instruments and Hedström files. Material and Methods: sixty mandibular incisors with a single canal were instrumented and obturated by cold lateral compaction. For retreatment, specimens were randomly divided into four groups (n = 15: Hedström files with or without solvent; D-RaCe system and Mtwo retreatment system. Debris extruded apically during the removal of canal filling material was collected into preweighed Eppendorf tubes. The tubes were then stored in an incubator at 70°C for 5 days. The weight of the dry extruded debris was established by subtracting the preretreatment and postretreatment weight of the Eppendorf tubes for each group. The mean weights of extruded material were analyzed by one-way ANOVA. Results: the results showed that all retreatment techniques caused apical extrusion of debris, but no statistically significant difference was observed between groups (p>0.05. Conclusion: under the conditions of this study, all retreatment techniques caused apical debris extrusion.

Incidence of flare-ups and evaluation of quality after retreatment of resorcinol-formaldehyde resin ("Russian Red Cement") endodontic therapy.

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Gound, Tom G; Marx, David; Schwandt, Nathan A

2003-10-01

The purpose of this retrospective study was to evaluate the quality of treatment and incidence of flare-ups when teeth with resorcinol-formaldehyde resin are retreated in a postgraduate endodontic clinic. Fifty-eight cases were included in this study. Obturated and unfilled canal space was measured on radiographs. Forty-eight percent of the total canal space was filled before retreatment; 90% was filled after retreatment. After retreatment, obturations were rated as optimal in 59%, improved in 33%, unchanged in 6%, and worse in 2%. Seven patients (12%) had postretreatment flare-ups. Data were statistically analyzed using the Cochran-Armitage Test for Discrete Variables. No statistical difference in the incidence of flare-ups was found in teeth that before treatment had more than half the canal space filled compared to teeth with less than half, cases with pre-existing periradicular radiolucencies compared to cases with normal periradicular appearance, symptomatic cases compared to asymptomatic cases, or cases with optimal fillings after retreatment compared to less than optimal cases. It was concluded that teeth with resorcinol-formaldehyde fillings might be retreated with a good prognosis for improving the radiographic quality, but a higher than normal incidence of flare-ups may occur.

Glacier retreat of the Tian Shan and its impact on the urban growth and environment evaluated from satellite remote sensing data

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Fu, B. H.; Guo, Q.; Yan, F.; Zhang, J.; Shi, P. L.; Ayinuer, M.; Xue, G. L.

2017-07-01

The retreat of mountain glaciers, notably in high Asia, provides evidence for the rise of global temperature. The mass balance is vital for the health of a glacier. If the amount of frozen precipitation in the accumulation zone exceeds the quantity of glacial ice loss due to melting or lies in the ablation zone, the glacier will advance. Conversely, if the accumulation is less than the ablation, the glacier will retreat. Glaciers in retreat will have negative mass balances, and if they do not reach an equilibrium between accumulation and ablation, will eventually disappear. Long-term changes of the mountain glaciers in the Tian Shan, Central Asia, are not well constrained. Analyses of satellite remote sensing data combined with the ground observations reveal a 37.5% decline of glaciered area from 1989 to 2014 in No.1 Glacier, the headwaters of the Urumqi River basin, Chinese Tian Shan, which could be linked to increased summer melting. The results show that the area of glaciers was reduced from 31.55 km2 in 18 August 1989 to 28.66 km2 in 24 August 1994 and 19.74 km2 in 31 August 2014. The glacier area was reduced by 0.47 km2/per year in recent 25 years since 1989, and the annual reduction was 1.5%. Meanwhile, the urban area of Urumqi, the biggest city of Xinjiang Uygur Autonomous Region, increased from 156 km2 in 1989 to 555 km2 in 2014. Correspondingly, the population of permanent residents increased from 1.06 million in 1989 to 3.53 million in 2014. We suggest that the decline of glacier area is driven primarily by summer melting and, possibly, linked to the combined effects of the global rise in temperatures and black carbon/CO2 emission from coal-fired power plants, cement plants and petroleum chemical plants from the nearby Urumqi and surrounding regions. The continuing retreat of glaciers will have a number of different quantitative impacts. Populations in the arid Central Asia regions are heavily dependent on snow and glacier melt for their irrigation and

Carbon Source-Dependent Inducible Metabolism of Veratryl Alcohol and Ferulic Acid in Pseudomonas putida CSV86

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Mohan, Karishma

2017-01-01

ABSTRACT Pseudomonas putida CSV86 degrades lignin-derived metabolic intermediates, viz., veratryl alcohol, ferulic acid, vanillin, and vanillic acid, as the sole sources of carbon and energy. Strain CSV86 also degraded lignin sulfonate. Cell respiration, enzyme activity, biotransformation, and high-pressure liquid chromatography (HPLC) analyses suggest that veratryl alcohol and ferulic acid are metabolized to vanillic acid by two distinct carbon source-dependent inducible pathways. Vanillic acid was further metabolized to protocatechuic acid and entered the central carbon pathway via the β-ketoadipate route after ortho ring cleavage. Genes encoding putative enzymes involved in the degradation were found to be present at fer, ver, and van loci. The transcriptional analysis suggests a carbon source-dependent cotranscription of these loci, substantiating the metabolic studies. Biochemical and quantitative real-time (qRT)-PCR studies revealed the presence of two distinct O-demethylases, viz., VerAB and VanAB, involved in the oxidative demethylation of veratric acid and vanillic acid, respectively. This report describes the various steps involved in metabolizing lignin-derived aromatic compounds at the biochemical level and identifies the genes involved in degrading veratric acid and the arrangement of phenylpropanoid metabolic genes as three distinct inducible transcription units/operons. This study provides insight into the bacterial degradation of lignin-derived aromatics and the potential of P. putida CSV86 as a suitable candidate for producing valuable products. IMPORTANCE Pseudomonas putida CSV86 metabolizes lignin and its metabolic intermediates as a carbon source. Strain CSV86 displays a unique property of preferential utilization of aromatics, including for phenylpropanoids over glucose. This report unravels veratryl alcohol metabolism and genes encoding veratric acid O-demethylase, hitherto unknown in pseudomonads, thereby providing new insight into the

Treatment and retreatment with omalizumab in chronic spontaneous urticaria: Real life experience with twenty-five patients.

Science.gov (United States)

Türk, Murat; Yılmaz, İnsu; Bahçecioğlu, Sakine Nazik

2018-01-01

Previous data have shown the high efficacy of omalizumab in chronic spontaneous urticaria (CSU). However, factors that may be effective on the response to therapy, relapse rates after drug discontinuation, and efficacy of retreatment remain unclear. This study aimed to determine the efficacy of omalizumab in CSU refractory to conventional therapy, to identify possible factors affecting treatment response and relapse, and also to evaluate the efficacy of retreatment on relapsed disease. The data of CSU patients treated with 300 mg/month omalizumab for at least 3 months were retrospectively analyzed. In order to evaluate the efficacy of treatment and retreatment, baseline and follow-up concomitant medication score (CMS) and urticaria activity score (UAS) were calculated. Possible factors affecting treatment response and relapse were identified. Twenty-five patients were included. The median duration of omalizumab therapy was 6 (6-12) months. Of the patients with baseline UAS 6 (5.5-6) and CMS 13 (10-15), 8 (32%) had complete response (UAS = 0) and 2 (8%) were non-responders after 3 months of therapy. None of the complete responders were positive for IgG-anti-TPO. After discontinuation of omalizumab therapy, 11 (61%) patients experienced relapse and 10 of them received retreatment with omalizumab. Half of the patients had complete response, and half had partial response (UAS = 1-4) after retreatment. No treatment related adverse events were documented. Omalizumab has high efficacy in both the treatment and retreatment of CSU; however, relapse rates after discontinuation are high. Autoimmune markers may be helpful in predicting treatment response and relapse. Copyright © 2017 Japanese Society of Allergology. Production and hosting by Elsevier B.V. All rights reserved.

Comparison of retreatment ability of full-sequence reciprocating instrumentation and 360° rotary instrumentation.

Science.gov (United States)

Capar, Ismail Davut; Gok, Tuba; Orhan, Ezgi

2015-12-01

The purpose of the present study was to investigate the amount of root canal filling material after root canal filling removal with 360° rotary instrumentation or reciprocating motion with the same file sequence. Root canals of the 36 mandibular premolars were shaped with ProTaper Universal instruments up to size F2 and filled with corresponding single gutta-percha cone and sealer. The teeth were assigned to two retreatment groups (n = 18): group 1 360° rotational motion and group 2 reciprocating motion of ATR Tecnika motors (1310° clockwise and 578° counterclockwise). Retreatment procedure was performed with ProTaper Universal retreatment files with a sequence of D1-3 and ProTaper Universal F3 instruments. Total time required to remove filling material were recorded. Remaining filling material was examined under stereomicroscope at ×8 magnification. The data were analysed statistically using the Mann-Whitney U test, and testing was performed at 95 % confidence level (p  0.05) in terms of remaining filling material. The total time required for retreatment was shorter in 360° rotational motion group compared to reciprocating motion group (p instruments with reciprocating motion of ATR motor and conventional rotary motion have similar efficacy in root canal filling removal.

Composition of amino acid using carbon monoxide. Amide carbonylation reaction

Energy Technology Data Exchange (ETDEWEB)

Izawa, Kunisuke (Ajinomoto Co., Inc., Tokyo (Japan))

1989-02-01

Amide carbonylation reaction is a method to compose N-acyl-{alpha}-amino acid from aldehyde, carboxylic acid amide, and carbon monoxide in a phase and with high yield. Unlike the conventional Strecker reaction, this method does not use HCN which is in question on public pollution and does not require hydrolysis. This amide carbonylation reaction was discovered by Wakamatsu and others of Ajinomoto Co.,Ltd. Present application examples of this method are the composition of N-acetyl amino acid from the aldehyde class, the composition of N-Acyl amino acid from olefin, the composition of N-acyl or acetyl amino acid from the raw material of alcohol and the halide class, the composition of N-acyl or acetyl amino acid via the isomerization of epoxide and allyl alcohol, the composition of amino dicarboxylic acid, applying deoxidation of ring acid anhydride, the composition of N-acyl amino acid from the raw material of the amine class, the stereoselective composition of -substitution ring-{alpha}-amino acid, and the composition of amino aldehyde. 24 refs., 2 figs., 2 tabs.

Electrochemical Determination of Glycoalkaloids Using a Carbon Nanotubes-Phenylboronic Acid Modified Glassy Carbon Electrode

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Huiying Wang

2013-11-01

Full Text Available A versatile strategy for electrochemical determination of glycoalkaloids (GAs was developed by using a carbon nanotubes-phenylboronic acid (CNTs-PBA modified glassy carbon electrode. PBA reacts with α-solanine and α-chaconine to form a cyclic ester, which could be utilized to detect GAs. This method allowed GA detection from 1 μM to 28 μM and the detection limit was 0.3 μM. Affinity interaction of GAs and immobilized PBA caused an essential change of the peak current. The CNT-PBA modified electrodes were sensitive for detection of GAs, and the peak current values were in quite good agreement with those measured by the sensors.

Potentially bioavailable natural organic carbon and hydrolyzable amino acids in aquifer sediments

Science.gov (United States)

Thomas, Lashun K.; Widdowson, Mark A.; Novak, John T.; Chapelle, Francis H.; Benner, Ronald; Kaiser, Karl

2012-01-01

This study evaluated the relationship between concentrations of operationally defined potentially bioavailable organic -carbon (PBOC) and hydrolyzable amino acids (HAAs) in sediments collected from a diverse range of chloroethene--contaminated sites. Concentrations of PBOC and HAA were measured using aquifer sediment samples collected at six selected study sites. Average concentrations of total HAA and PBOC ranged from 1.96 ± 1.53 to 20.1 ± 25.6 mg/kg and 4.72 ± 0.72 to 443 ± 65.4 mg/kg, respectively. Results demonstrated a statistically significant positive relationship between concentrations of PBOC and total HAA present in the aquifer sediment (p amino acids are known to be readily biodegradable carbon compounds, this relationship suggests that the sequential chemical extraction procedure used to measure PBOC is a useful indicator of bioavailable carbon in aquifer sediments. This, in turn, is consistent with the interpretation that PBOC measurements can be used for estimating the amount of natural organic carbon available for driving the reductive dechlorination of chloroethenes in groundwater systems.

Postoperative pain after endodontic retreatment: single- versus two-visit treatment.

Science.gov (United States)

Yoldas, Oguz; Topuz, Aysin; Isçi, A Sehnaz; Oztunc, Haluk

2004-10-01

The purpose of this clinical study was to determine the effect of 1- or 2-visit root canal treatment on the postoperative pain in the retreatment cases. Two hundred eighteen cases that required retreatment were included in the study. Obturated and unfilled canal space and the status of periapical tissues were evaluated according to the PAI index. The patients were subcategorized in regard to the presence or the absence of preoperative pain. Approximately half of each category was treated in 1 appointment. After removing the previous root canal obturation materials and biomechanic preparation of root canals, the teeth in the 1-visit group were obturated at the first appointment by using AH 26 sealer and laterally compacted gutta-percha, and those in the 2-visit group were medicated with calcium hydroxide-chlorhexidine combination and then closed with a temporary filling material. One week after the initial appointment, patients were asked about the occurrence of postoperative pain. The level of discomfort was rated as no pain, mild pain, moderate pain, or severe pain (flare-up). Data were statistically analyzed using the chi-squared and Fischer exact tests. Eight patients from the 1-visit group and 2 patients from the 2-visit group had flare-ups. There was a statistical difference between the groups (P endodontic treatment with intracanal medication was found to be effective in reducing postoperative pain of previously symptomatic teeth and decreased the number of flare-ups in all retreatment cases.

Adsorption of lignite-derived humic acids on coal-based mesoporous activated carbons.

Science.gov (United States)

Lorenc-Grabowska, Ewa; Gryglewicz, Grazyna

2005-04-15

The adsorption by a coal-based mesoporous activated carbon of humic acids (HAs) isolated from two Polish lignites was studied. For comparison, a commercial Aldrich humic acid was also included into this study. The differences in chemical structure and functional groups of HAs were determined by elemental analysis and infrared spectroscopy DRIFT. Two activated carbons used differed in terms of mesopore volume, mesopore size distribution, and chemical properties of the surface. The kinetics of adsorption of HAs have been discussed using three kinetic models, i.e., the first-order Lagergren model, the pseudo-second-order model, and the intraparticle diffusion model. It was found that the adsorption of HAs from alkaline solution on mesoporous activated carbon proceeds according to the pseudo-second-order model. The correlation coefficients were close to 1. The intraparticle diffusion of HA molecules within the carbon particle was identified to be the rate-limiting step. Comparing the two activated carbons, the carbon with a higher volume of pores with widths of 10-50 nm showed a greater removal efficiency of HA. An increase in the Freundlich adsorption capacity with decreasing carbon content of HA was observed. Among the HAs studied, S-HA shows characteristics indicating the highest contribution of small-size fraction. The S-HA was removed by both activated carbons to the highest extent. The effect of pH solution on the adsorption of HA was examined over the range pH 5.4-12.2. It was found that the extent of adsorption decreased with decreasing pH of the solution.

Norepinephrine-modified glassy carbon electrode for the simultaneous determination of ascorbic acid and uric acid

International Nuclear Information System (INIS)

Zare, H.R.; Memarzadeh, F.; Ardakani, M. Mazloum; Namazian, M.; Golabi, S.M.

2005-01-01

The oxidation of norepinephrine (NE) on a preactivated glassy carbon electrode leads to the formation of a deposited layer of about 4.2 x 10 -10 mol cm -2 at the surface of the electrode. The electron transfer rate constant, k s , and charge transfer coefficient, α, for electron transfer between the electrode and immobilized NE film were calculated as 44 s -1 and 0.46, respectively. The NE-modified glassy carbon electrode exhibited good electrocatalytic properties towards ascorbic acid (AA) oxidation in phosphate buffer (pH 7.0) with an overpotential of about 475 mV lower than that of the bare electrode. The electrocatalytic response was evaluated by cyclic voltammetry, chronoamperometry, amperometry and rotating disk voltammetry. The overall number of electrons involved in the catalytic oxidation of AA and the number of electrons involved in the rate-determining step are 2 and 1, respectively. The rate constant for the catalytic oxidation of AA was evaluated by RDE voltammetry and an average value of k h was found to be 8.42 x 10 3 M -1 s -1 . Amperometric determination of AA in stirred solution exhibits a linear range of 2.0-1300.0 μM (correlation coefficient 0.9999) and a detection limit of 0.076 μM. The precision of amperometry was found to be 1.9% for replicate determination of a 49.0 μM solution of AA (n = 6). In differential pulse voltammetric measurements, the NE-modified glassy carbon electrode can separate the AA and uric acid (UA) signals. Ascorbic acid oxidizes at more negative potential than UA. Also, the simultaneous determination of UA and AA is achieved at the NE-modified electrode

Preparation of iron oxide-impregnated spherical granular activated carbon-carbon composite and its photocatalytic removal of methylene blue in the presence of oxalic acid.

Science.gov (United States)

Kadirova, Zukhra C; Hojamberdiev, Mirabbos; Katsumata, Ken-Ichi; Isobe, Toshihiro; Matsushita, Nobuhiro; Nakajima, Akira; Sharipov, Khasan; Okada, Kiyoshi

2014-01-01

The spherical granular activated carbon-carbon composites (GAC-Fe) with different iron oxide contents (Fe mass% = 0.6-10) were prepared by a pore volume impregnation method. The X-ray diffraction (XRD), scanning electron microscopy (SEM), and N2-adsorption results confirm the presence of amorphous iron oxide, pyrolytic carbon, and graphitized globular carbon nanoparticles covered with amorphous carbon in the CAG-Fe. The rate of photodegradation of methylene blue (MB) in aqueous solution under UV light in the presence of oxalic acid correlates with porosity of the prepared materials. The total MB removal includes the combination of adsorption and photodegradation without the addition of H2O2. The results of total organic carbon (TOC) analysis reveal that the decolorization of MB in aqueous solution containing oxalic acid corresponds to the decomposition of organic compounds to CO2 and H2O.

Collagen tissue treated with chitosan solutions in carbonic acid for improved biological prosthetic heart valves

Energy Technology Data Exchange (ETDEWEB)

Gallyamov, Marat O., E-mail: glm@spm.phys.msu.ru [Faculty of Physics, Lomonosov Moscow State University, Leninskie gory 1–2, Moscow 119991 (Russian Federation); Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilova 28, Moscow 119991 (Russian Federation); Chaschin, Ivan S. [Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilova 28, Moscow 119991 (Russian Federation); Khokhlova, Marina A. [Faculty of Physics, Lomonosov Moscow State University, Leninskie gory 1–2, Moscow 119991 (Russian Federation); Grigorev, Timofey E. [Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilova 28, Moscow 119991 (Russian Federation); Bakuleva, Natalia P.; Lyutova, Irina G.; Kondratenko, Janna E. [Bakulev Scientific Center for Cardiovascular Surgery of the Russian Academy of Medical Sciences, Roublyevskoe Sh. 135, Moscow 121552 (Russian Federation); Badun, Gennadii A.; Chernysheva, Maria G. [Radiochemistry Division, Faculty of Chemistry, Lomonosov Moscow State University, Leninskie gory 1–2, Moscow 119991 (Russian Federation); Khokhlov, Alexei R. [Faculty of Physics, Lomonosov Moscow State University, Leninskie gory 1–2, Moscow 119991 (Russian Federation); Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilova 28, Moscow 119991 (Russian Federation)

2014-04-01

Calcification of bovine pericardium dramatically shortens typical lifetimes of biological prosthetic heart valves and thus precludes their choice for younger patients. The aim of the present work is to demonstrate that the calcification is to be mitigated by means of treatment of bovine pericardium in solutions of chitosan in carbonic acid, i.e. water saturated with carbon dioxide at high pressure. This acidic aqueous fluid unusually combines antimicrobial properties with absolute biocompatibility as far as at normal pressure it decomposes spontaneously and completely into H{sub 2}O and CO{sub 2}. Yet, at high pressures it can protonate and dissolve chitosan materials with different degrees of acetylation (in the range of 16–33%, at least) without any further pretreatment. Even exposure of the bovine pericardium in pure carbonic acid solution without chitosan already favours certain reduction in calcification, somewhat improved mechanical properties, complete biocompatibility and evident antimicrobial activity of the treated collagen tissue. The reason may be due to high extraction ability of this peculiar compressed fluidic mixture. Moreover, exposure of the bovine pericardium in solutions of chitosan in carbonic acid introduces even better mechanical properties and highly pronounced antimicrobial activity of the modified collagen tissue against adherence and biofilm formation of relevant Gram-positive and Gram-negative strains. Yet, the most important achievement is the detected dramatic reduction in calcification for such modified collagen tissues in spite of the fact that the amount of the thus introduced chitosan is rather small (typically ca. 1 wt.%), which has been reliably detected using original tritium labelling method. We believe that these improved properties are achieved due to particularly deep and uniform impregnation of the collagen matrix with chitosan from its pressurised solutions in carbonic acid. - Highlights: • Treatment of GA

Collagen tissue treated with chitosan solutions in carbonic acid for improved biological prosthetic heart valves

International Nuclear Information System (INIS)

Gallyamov, Marat O.; Chaschin, Ivan S.; Khokhlova, Marina A.; Grigorev, Timofey E.; Bakuleva, Natalia P.; Lyutova, Irina G.; Kondratenko, Janna E.; Badun, Gennadii A.; Chernysheva, Maria G.; Khokhlov, Alexei R.

2014-01-01

Calcification of bovine pericardium dramatically shortens typical lifetimes of biological prosthetic heart valves and thus precludes their choice for younger patients. The aim of the present work is to demonstrate that the calcification is to be mitigated by means of treatment of bovine pericardium in solutions of chitosan in carbonic acid, i.e. water saturated with carbon dioxide at high pressure. This acidic aqueous fluid unusually combines antimicrobial properties with absolute biocompatibility as far as at normal pressure it decomposes spontaneously and completely into H 2 O and CO 2 . Yet, at high pressures it can protonate and dissolve chitosan materials with different degrees of acetylation (in the range of 16–33%, at least) without any further pretreatment. Even exposure of the bovine pericardium in pure carbonic acid solution without chitosan already favours certain reduction in calcification, somewhat improved mechanical properties, complete biocompatibility and evident antimicrobial activity of the treated collagen tissue. The reason may be due to high extraction ability of this peculiar compressed fluidic mixture. Moreover, exposure of the bovine pericardium in solutions of chitosan in carbonic acid introduces even better mechanical properties and highly pronounced antimicrobial activity of the modified collagen tissue against adherence and biofilm formation of relevant Gram-positive and Gram-negative strains. Yet, the most important achievement is the detected dramatic reduction in calcification for such modified collagen tissues in spite of the fact that the amount of the thus introduced chitosan is rather small (typically ca. 1 wt.%), which has been reliably detected using original tritium labelling method. We believe that these improved properties are achieved due to particularly deep and uniform impregnation of the collagen matrix with chitosan from its pressurised solutions in carbonic acid. - Highlights: • Treatment of GA-stabilised bovine

Timing, cause and impact of the late Eocene stepwise sea retreat from the Tarim Basin (west China)

NARCIS (Netherlands)

Bosboom, R.|info:eu-repo/dai/nl/322947359; Dupont-Nivet, G.|info:eu-repo/dai/nl/313092559; Grothe, A.|info:eu-repo/dai/nl/338017712; Brinkhuis, H.|info:eu-repo/dai/nl/095046097; Villa, G.; Mandic, O.; Stoica, M.; Kouwenhoven, T.J.|info:eu-repo/dai/nl/191377406; Huang, W.; Yang, W.; Guo, Z.

2014-01-01

A vast shallow epicontinental sea extended across Eurasia and was well-connected to the Western Tethys before it retreated westward and became isolated as the Paratethys Sea. However, the palaeogeography and the timing of this westward retreat are too poorly constrained to determine potential wider

Synthesis of biodiesel from waste vegetable oil with large amounts of free fatty acids using a carbon-based solid acid catalyst

Energy Technology Data Exchange (ETDEWEB)

Shu, Qing; Gao, Jixian; Nawaz, Zeeshan; Liao, Yuhui; Wang, Dezheng; Wang, Jinfu [Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing 100084 (China)

2010-08-15

A carbon-based solid acid catalyst was prepared by the sulfonation of carbonized vegetable oil asphalt. This catalyst was employed to simultaneously catalyze esterification and transesterification to synthesis biodiesel when a waste vegetable oil with large amounts of free fatty acids (FFAs) was used as feedstock. The physical and chemical properties of this catalyst were characterized by a variety of techniques. The maximum conversion of triglyceride and FFA reached 80.5 wt.% and 94.8 wt.% after 4.5 h at 220 C, when using a 16.8 M ratio of methanol to oil and 0.2 wt.% of catalyst to oil. The high catalytic activity and stability of this catalyst was related to its high acid site density (-OH, Broensted acid sites), hydrophobicity that prevented the hydration of -OH species, hydrophilic functional groups (-SO{sub 3}H) that gave improved accessibility of methanol to the triglyceride and FFAs, and large pores that provided more acid sites for the reactants. (author)

Fatty acid methyl esters, carbon nanotubes and carbon nanowalls coatings such as lubricity improvers of low sulfur diesel fuels

Energy Technology Data Exchange (ETDEWEB)

Cursaru, Diana Luciana; Tanasescu, Constantin [Petroleum-Gas Univ. of Ploiesti (Romania); Vizireanu, Sorin [National Institute for Laser, Plasma and Radiation Physics (Romania)

2013-06-01

In this study the lubricity of diesel fuel was restored by different methods, firstly by classic addition of fatty acid methyl esters or by dispersing carbon nanotubes into diesel fuels and secondly, by protecting the metallic surfaces which are in the direct contact to the low sulfur diesel fuel, by application of solid carbon nanowalls coatings synthesized by radiofrequency plasma beam deposition. The fatty acid methyl esters were prepared by transesterification of the sun flower oil in the presence of methanol. The carbon nanotubes were synthesized by CO disproportionation method and were characterized by RAMAN spectroscopy and high resolution transmission electron microscopy (TEM). The CNWs layers, before the friction tests, were examined by scanning electron microscopy (SEM), atomic force microscopy (AFM) and Raman spectroscopy, while the wear on the steel balls was investigated by optical microscopy of the HRRT apparatus and the wear track on the steel disk was investigated by SEM, AFM and profilometry. The lubricity was measured using the High Frequency Reciprocating Rig (HFRR) method. It has been found that CNWs layers exhibit a lubricating potential for the rubbed surfaces in the presence of low sulfur diesel fuels. Tribological analyses of various carbon materials revealed that the friction coefficient of carbon nanowalls is close to the values obtained for graphite. (orig.)

Evaluation of apically extruded debris during root canal retreatment with several NiTi systems.

Science.gov (United States)

Dincer, A N; Er, O; Canakci, B C

2015-12-01

To compare the amount of debris extruded apically during root canal retreatment using ProTaper, Mtwo and Reciproc instruments with hand H-files. In total, 60 freshly extracted human mandibular incisor teeth were used. All root canals were prepared with a Reciproc R25 file than filled with Gutta-percha and AH Plus sealer using cold lateral condensation before being assigned randomly to four groups (n = 15 each). In group 1, root fillings were removed with the Protaper Universal retreatment system; ProTaper Universal F3 and F4 instruments were used for the final preparation. In group 2, root fillings were removed with the Mtwo retreatment system; Mtwo size 30, .06 taper, size 35, .06 taper and size 40, .06 taper files were used for the final preparation. In group 3, root fillings were removed with Reciproc R25 instruments; Reciproc R40 instruments were used for the final preparation. In group 4, the root fillings were removed with Gates Glidden burs and sizes 35, 30 and 25 H-files; for final preparation, a size 40 H-file was used. Glass vials were used for debris collection. The vials were weighed before and after Gutta-percha removal. Additionally, the times required for the retreatment procedures were recorded. Data were analysed statistically using one-way analysis of variance. The Reciproc system produced significantly smaller amounts of apical extruded debris than the other groups (P ProTaper groups. The ProTaper and Reciproc groups required significantly less time than the Mtwo and H-file groups (P hand filing. Use of the ProTaper and Reciproc instruments required less time for retreatment procedures than use of the Mtwo or H-file. © 2014 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Extensive Holocene ice sheet grounding line retreat and uplift-driven readvance in West Antarctica

Science.gov (United States)

Kingslake, J.; Scherer, R. P.; Albrecht, T.; Coenen, J. J.; Powell, R. D.; Reese, R.; Stansell, N.; Tulaczyk, S. M.; Whitehouse, P. L.

2017-12-01

The West Antarctic Ice Sheet (WAIS) reached its Last Glacial Maximum (LGM) extent 29-14 kyr before present. Numerical models used to project future ice-sheet contributions to sea-level rise exploit reconstructions of post-LGM ice mass loss to tune model parameterizations. Ice-sheet reconstructions are poorly constrained in areas where floating ice shelves or a lack of exposed geology obstruct conventional glacial-geological techniques. In the Weddell and Ross Sea sectors, ice-sheet reconstructions have traditionally assumed progressive grounding line (GL) retreat throughout the Holocene. Contrasting this view, using three distinct lines of evidence, we show that the GL retreated hundreds of kilometers inland of its present position, before glacial isostatic rebound during the Mid to Late Holocene caused the GL to readvance to its current position. Evidence for retreat and readvance during the last glacial termination includes (1) widespread radiocarbon in sediment cores recovered from beneath ice streams along the Siple and Gould Coasts, indicating marine exposure at least 200 km inland of the current GL, (2) ice-penetrating radar observations of relic crevasses and other englacial structures preserved in slow-moving grounded ice, indicating ice-shelf grounding and (3) an ensemble of new ice-sheet simulations showing widespread post-LGM retreat of the GL inland of its current location and later readvance. The model indicates that GL readvance across low slope ice-stream troughs requires uplift-driven grounding of the ice shelf on topographic highs (ice rises). Our findings highlight ice-shelf pinning points and lithospheric response to unloading as drivers of major ice-sheet fluctuations. Full WAIS collapse likely requires GL retreat well beyond its current position in the Ronne and Ross Sectors and linkage via Amundsen Sea sector glaciers.

Landmark Study Reveals Antarctic Glacier's Long History of Retreat

OpenAIRE

Kuska, Dale M.

2016-01-01

Faculty Showcase Archive Article Approved for public release; distribution is unlimited. A major study, released in late November in the journal “Nature,” reveals the history of retreat of the massive Pine Island Glacier (PIG) in western Antarctica, widely considered one of the largest contributors to global sea-level rise.

HIGH PRESSURE VAPOR-LIQUID EQUILIBRIA OF PALM FATTY ACIDS DISTILLATES-CARBON DIOXIDE SYSTEM

Directory of Open Access Journals (Sweden)

Nélio T. MACHADO

1997-12-01

Full Text Available Vapor-Liquid equilibria of palm fatty acids distillates/carbon dioxide system has been investigated experimentally at temperatures of 333, 353, and 373 K and pressures of 20, 23, 26, and 29 MPa using the static method. Experimental data for the quasi-binary system palm fatty acids distillates/carbon dioxide has been correlated with Redlich-Kwong-Aspen equation of state. Modeling shows good agreement with experimental data. Selectivity obtained indicates that supercritical carbon dioxide is a reasonable solvent for separating saturated (palmitic acid and unsaturated (oleic+linoleic acids fatty acids from palm fatty acids distillates in a continuous multistage countercurrent column.Foi investigado experimentalmente o equilíbrio líquido-vapor para o sistema Destilado Ácido de Óleo de Palma (PFAD/Dióxido de Carbono, nas temperaturas de 333, 353 e 373 K e pressões de 20, 23, 26 e 29 MPa, usando-se o método estático. Os dados experimentais do sistema pseudo-binário PFAD/CO2 foram correlacionados com a equação de estado de Redlich-Kwong do pacote computacional ASPEN. O modelo reproduz bem os resultados experimentais. A seletividade obtida indica que o CO2 supercrítico é um solvente razoável para a separação em coluna multi-estágio e contínua, do ácido graxo saturado (ácido palmítico daqueles insaturados (ácido oleico e ácido linoleico contidos no PFAD.

From Retreat to Re-engagement: The New American Foreign Policy ...

African Journals Online (AJOL)

From Retreat to Re-engagement: The New American Foreign Policy for ... that the re-engagement with Sub-Saharan Africa, is based on US perception of threats ... in the subordination of the region to the world's only superpower and its allies.

Comparison of inhibition effects of some benzoic acid derivatives on sheep heart carbonic anhydrase

Science.gov (United States)

Kiliç, Deryanur; Yildiz, Melike; Şentürk, Murat; Erdoǧan, Orhan; Küfrevioǧlu, Ömer Irfan

2016-04-01

Carbonic anhydrase (CA) is a family of metalloenzymes that requires Zn as a cofactor and catalyze the quick conversion of CO2 to HCO3- and H+. Inhibitors of the carbonic anhydrases (CAs) have medical usage of significant diseases such as glaucoma, epilepsy, gastroduodenal ulcers, acid-base disequilibria and neurological disorders. In the present study, inhibition of CA with some benzoic derivatives (1-6) were investigated. Sheep heart CA (shCA) enzyme was isolated by means of designed affinity chromatography gel (cellulose-benzyl-sulfanylamide) 42.45-fold in a yield of 44 % with 564.65 EU/mg. Purified shCA enzyme was used in vitro studies. In the studies, IC50 values were calculated for 3-aminobenzoic acid (1), 4-aminobenzoic acid (2), 2-hydroxybenzoic acid (3), 2-benzoylbenzoic acid (4), 2,3-dimethoxybenzoic acid (5), and 3,4,5-trimethoxybenzoic acid (6), showing the inhibition effects on the purified enzyme. Such molecules can be used as pioneer for discovery of novel effective CA inhibitors for medicinal chemistry applications.

Long-term cliff retreat and erosion hotspots along the central shores of the Monterey Bay National Marine Sanctuary

Science.gov (United States)

Moore, Laura J.; Griggs, Gary B.

2002-01-01

Quantification of cliff retreat rates for the southern half of Santa Cruz County, CA, USA, located within the Monterey Bay National Marine Sanctuary, using the softcopy/geographic information system (GIS) methodology results in average cliff retreat rates of 7–15 cm/yr between 1953 and 1994. The coastal dunes at the southern end of Santa Cruz County migrate seaward and landward through time and display net accretion between 1953 and 1994, which is partially due to development. In addition, three critically eroding segments of coastline with high average erosion rates ranging from 20 to 63 cm/yr are identified as erosion ‘hotspots’. These locations include: Opal Cliffs, Depot Hill and Manresa. Although cliff retreat is episodic, spatially variable at the scale of meters, and the factors affecting cliff retreat vary along the Santa Cruz County coastline, there is a compensation between factors affecting retreat such that over the long-term the coastline maintains a relatively smooth configuration. The softcopy/GIS methodology significantly reduces errors inherent in the calculation of retreat rates in high-relief areas (e.g. erosion rates generated in this study are generally correct to within 10 cm) by removing errors due to relief displacement. Although the resulting root mean squared error for erosion rates is relatively small, simple projections of past erosion rates are inadequate to provide predictions of future cliff position. Improved predictions can be made for individual coastal segments by using a mean erosion rate and the standard deviation as guides to future cliff behavior in combination with an understanding of processes acting along the coastal segments in question. This methodology can be applied on any high-relief coast where retreat rates can be measured.

Influence of nitric acid concentration on the characteristics of active carbons obtained from a mineral coal

Energy Technology Data Exchange (ETDEWEB)

Khelifi, A.; Temdrara, L.; Addoun, A. [Laboratoire d' Etude Physicochimique des Materiaux et Application a l' Environnement, Faculte de Chimie, USTHB, BP. 32 El Alia, Bab Ezzouar 16111, Algiers (Algeria); Almazan-Almazan, M.C.; Perez-Mendoza, M.; Domingo-Garcia, M.; Lopez-Garzon, F.J [Departamento de Quimica Inorganica, Facultad de Ciencias, 18071 Granada (Spain); Lopez-Domingo, F.J. [Departamento de CCIA, ETS de Ingenieria Informatica y Telecomunicacion, Granada, 18071 (Spain)

2010-10-15

This paper deals with the effect of the concentration of nitric acid solutions on the properties of activated carbons obtained by the oxidation of a parent activated carbon. For this purpose a mineral coal from Algeria has been used as raw material to prepare the parent active carbon AC. This was further treated with nitric acid solutions. The analysis of the samples includes the chemical and textural characterization. The former was carried out by selective titrations and FTIR spectroscopy. The latter, by nitrogen and carbon dioxide adsorption at 77 and 273 K, respectively, and by adsorption of organic probes (benzene, dichloromethane, cyclohexane and 2,2-dimethyl butane) at 303 K. The nitrogen adsorption isotherms have been analysed by using the BET equation, {alpha}{sub s}-method and molecular simulation. The Dubinin-Radushkevich approach has been applied to the carbon dioxide and vapours adsorption data. The results show that the treatment with 2 N nitric acid solution is very appropriate because it introduces a large amount of oxygen containing groups with a small change of the textural characteristics of the parent AC. More concentrated nitric acid solutions change in large extent the textural properties although they also introduce large amount of chemical groups. (author)

The Path of Carbon in Photosynthesis VIII. The Role of Malic Acid

Science.gov (United States)

Bassham, James A.; Benson, Andrew A.; Calvin, Melvin

1950-01-25

Malonate has been found to inhibit the formation of malic acid during short periods of photosynthesis with radioactive carbon dioxide. This result, together with studies which show the photosynthetic cycle to be operating normally at the same time, indicates that malic acid is not an intermediate in photosynthesis but is probably closely related to some intermediate of the cycle. Absence of labeled succinic and fumaric acids in these experiments, in addition to the failure of malonate to inhibit photosynthesis, precludes the participation of these acids as intermediates in photosynthesis.

Non-surgical retreatment of a failed apicoectomy without retrofilling using white mineral trioxide aggregate as an apical barrier.

Science.gov (United States)

Stefopoulos, Spyridon; Tzanetakis, Giorgos N; Kontakiotis, Evangelos G

2012-01-01

Root-end resected teeth with persistent apical periodontitis are usually retreated surgically or a combination of non-surgical and surgical retreatment is employed. However, patients are sometimes unwilling to be subjected to a second surgical procedure. The apical barrier technique that is used for apical closure of immature teeth with necrotic pulps may be an alternative to non-surgically retreat a failed apicoectomy. Mineral trioxide aggregate (MTA) has become the material of choice in such cases because of its excellent biocompatibility, sealing ability and osseoinductive properties. This case report describes the non-surgical retreatment of a failed apicoectomy with no attempt at retrofilling of a maxillary central incisor. White MTA was used to induce apical closure of the wide resected apical area. Four-year follow-up examination revealed an asymptomatic, fully functional tooth with a satisfactory healing of the apical lesion. White MTA apical barrier may constitute a reliable and efficient technique to non-surgically retreat teeth with failed root-end resection. The predictability of such a treatment is of great benefit for the patient who is unwilling to be submitted to a second surgical procedure.

On the carbonic acid distributed in the atmosphere, of Alexander Von Humboldt

International Nuclear Information System (INIS)

Pelkoswski, Joaquin

2001-01-01

Translation that is made of a essay of Alexander Von Humboldt in which describes their own experiences related with the carbon dioxide (denominated carbonic acid in that time) in the atmosphere and in the we can capture the big difficulties around their measurement and their presence in the great gassy cover that surrounds us and it allows us to live

Rhizosphere bacterial carbon turnover is higher in nucleic acids than membrane lipids: implications for understanding soil carbon cycling

Directory of Open Access Journals (Sweden)

Ashish A. Malik

2015-04-01

Full Text Available Using a pulse-chase 13CO2 plant labeling experiment we compared the flow of plant carbon into macromolecular fractions of root-associated soil microorganisms. Time dependent 13C dilution patterns in microbial cellular fractions were used to calculate their turnover time. The turnover times of microbial biomolecules were found to vary: microbial RNA (19 h and DNA (30 h turned over fastest followed by chloroform fumigation extraction-derived soluble cell lysis products (14 d, while phospholipid fatty acids (PLFAs had the slowest turnover (42 d. PLFA/NLFA 13C analyses suggest that both mutualistic arbuscular mycorrhizal and saprophytic fungi are dominant in initial plant carbon uptake. In contrast, high initial 13C enrichment in RNA hints at bacterial importance in initial C uptake due to the dominance of bacterial derived RNA in total extracts of soil RNA. To explain this discrepancy, we observed low renewal rate of bacterial lipids, which may therefore bias lipid fatty acid based interpretations of the role of bacteria in soil microbial food webs. Based on our findings, we question current assumptions regarding plant-microbe carbon flux and suggest that the rhizosphere bacterial contribution to plant assimilate uptake could be higher. This highlights the need for more detailed quantitative investigations with nucleic acid biomarkers to further validate these findings.

Summary of the RHIC Retreat 2008

International Nuclear Information System (INIS)

Pilat, F.; Brennan, M.; Brown, K.; Fischer, W.; Montag, C.

2008-01-01

The main goal of the RHIC Retreat is to review last run's performance and prepare for the next. As always though we also discussed the longer term goals and plans for the facility to put the work in perspective and in the right priority. A straw-man plan for the facility was prepared for the DOE that assumes 30 cryoweek and running 2 species per year. The plan outlines RHIC operations for 2008-2012 and integrates well accelerator and detector upgrades to optimize the physics output with high luminosities. The plans includes guidance from the PAC and has been reviewed by DOE

Adsorption of 2,4-dichlorophenoxyacetic acid and 4-chloro-2-metylphenoxyacetic acid onto activated carbons derived from various lignocellulosic materials.

Science.gov (United States)

Doczekalska, Beata; Kuśmierek, Krzysztof; Świątkowski, Andrzej; Bartkowiak, Monika

2018-05-04

Adsorption of 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-chloro-2-metylphenoxyacetic acid (MCPA) from aqueous solution onto activated carbons derived from various lignocellulosic materials including willow, miscanthus, flax, and hemp shives was investigated. The adsorption kinetic data were analyzed using two kinetic models: the pseudo-first order and pseudo-second order equations. The adsorption kinetics of both herbicides was better represented by the pseudo-second order model. The adsorption isotherms of 2,4-D and MCPA on the activated carbons were analyzed using the Freundlich and Langmuir isotherm models. The equilibrium data followed the Langmuir isotherm. The effect of pH on the adsorption was also studied. The results showed that the activated carbons prepared from the lignocellulosic materials are efficient adsorbents for the removal of 2,4-D and MCPA from aqueous solutions.

Desorption of uranium from titanium-activated carbon composite adsorbent with acidic eluent, 2

International Nuclear Information System (INIS)

Hirotsu, Takahiro; Fujii, Ayako; Sakane, Kohji; Katoh, Shunsaku; Sugasaka, Kazuhiko

1984-01-01

The desorption of uranium from the granular titanium-activated carbon composite adsorbent (concentration of uranium: 25.5 mg/1-Ad), which adsorbed uranium from natural sea water, was examined by the column process with acidic eluent at room temperature. The column operation was able to be carried out without destruction of the granular adsorbent by the generation of the carbon dioxide, and free from disturbance of the eluent flow by precipitate of calcium sulfate dihydrate with sulfuric acid eluent. The amount of acid consumption by the adsorbent was 0.87 eq/1-Ad. The alkaline earth metals were eluted in the range of elution volume below 2 1/1-Ad, whereas uranium, iron, and titanium were eluted above 2 1/1-Ad. Therefore, uranium was separable from the alkaline earth metals which were adsorbed in the most quantity in the adsorbent. In the range of elution volume 2 to 12 1/1-Ad, the percentage of desorbed uranium and the concentration ratio of uranium were 80 %, 680 with 0.5 N sulfuric acid, and 59 %, 490 with 0.5 N hydrochloric acid, respectively. The percentage of dissolved titanium (DTI) was 0.3 % with 0.5 N sulfuric acid, 0.26 % with 0.5 N hydrochloric acid in the same range. (author)

Voltammetric determination of carbidopa and folic acid using a modified carbon nanotubes paste electrode

Directory of Open Access Journals (Sweden)

Keshtkar Nasrin

2015-01-01

Full Text Available A novel electrochemical sensor for the selective and sensitive detection of carbidopa in presence of large excess of folic acid at physiological pH was developed by the bulk modification of carbon paste electrode (CPE with carbon nanotubes (CNTs and vinylferrocene. Large peak separation, good sensitivity and stability allow this modified electrode to analyze carbidopa individually and simultaneously along with folic acid. Applying square wave voltammetry (SWV, a linear dynamic range of 1.0×10-6- 7.0×10-4 M with detection limit of 2.0×10-7 M was obtained for carbidopa. Finally, the proposed method was applied to the determination of carbidopa and folic acid in urine sample.

Observations and modeling of fjord sedimentation during the 30 year retreat of Columbia Glacier, AK

Science.gov (United States)

Love, Katherine B; Hallet, Bernard; Pratt, Thomas L.; O'Neel, Shad

2016-01-01

To explore links between glacier dynamics, sediment yields and the accumulation of glacial sediments in a temperate setting, we use extensive glaciological observations for Columbia Glacier, Alaska, and new oceanographic data from the fjord exposed during its retreat. High-resolution seismic data indicate that 3.2 × 108 m3 of sediment has accumulated in Columbia Fjord over the past three decades, which corresponds to ~5 mm a−1 of erosion averaged over the glaciated area. We develop a general model to infer the sediment-flux history from the glacier that is compatible with the observed retreat history, and the thickness and architecture of the fjord sediment deposits. Results reveal a fivefold increase in sediment flux from 1997 to 2000, which is not correlated with concurrent changes in ice flux or retreat rate. We suggest the flux increase resulted from an increase in the sediment transport capacity of the subglacial hydraulic system due to the retreat-related steepening of the glacier surface over a known subglacial deep basin. Because variations in subglacial sediment storage can impact glacial sediment flux, in addition to changes in climate, erosion rate and glacier dynamics, the interpretation of climatic changes based on the sediment record is more complex than generally assumed.

O2 electrocatalysis in acid media on iron naphthalocyanine impregnations. Effect of nitric acid treatment on different carbon black supports

NARCIS (Netherlands)

Coowar, F.; Contamin, O.; Savy, M.; Scarbeck, G.; van den Ham, D.; Riga, J.; Verbist, J.J.

1991-01-01

O2 electrocatalysis on (2,3)FeNPc impregnations on different carbon blacks was investigated in H2SO4 medium. The effect of nitric acid treatment on the carbon black support is to enhance both the activity and stability of the catalyst. Moreover, as seen by XPS, the dissolution of iron is impeded by

Increasing Research Productivity and Professional Development in Psychology With a Writing Retreat.

Science.gov (United States)

Stanley, Ian H; Hom, Melanie A; Chu, Carol; Joiner, Thomas E

2017-09-01

Writing is a core feature of the training requirements and career demands of psychology faculty members and graduate students. Within academic psychology, specifically, writing is vital for the generation of scientific knowledge through manuscripts and grant applications. Although resources exist regarding how to improve one's writing skills, few models have been described regarding how to promote a culture of writing productivity that realizes tangible deliverables, such as manuscripts and grant applications. In this article, we discuss the rationale, model, and initial outcome data of a writing retreat developed and implemented to increase research productivity among psychology faculty and trainees. We also review best practices for conducting writing retreats and identify key areas for future SoTL on advancing writing.

Enhancement of heat transfer for thermal energy storage application using stearic acid nanocomposite with multi-walled carbon nanotubes

International Nuclear Information System (INIS)

Li, TingXian; Lee, Ju-Hyuk; Wang, RuZhu; Kang, Yong Tae

2013-01-01

A latent heat storage nanocomposite made of stearic acid (SA) and multi-walled carbon nanotube (MWCNT) is prepared for thermal energy storage application. The thermal properties of the SA/MWCNT nanocomposite are characterized by SEM (scanning electron microscopy) and DSC (differential scanning calorimeter) analysis techniques, and the effects of different volume fractions of MWCNT on the heat transfer enhancement and thermal performance of stearic acid are investigated during the charging and discharging phases. The SEM analysis shows that the additive of MWCNT is uniformly distributed in the phase change material of stearic acid, and the DSC analysis reveals that the melting point of SA/MWCNT nanocomposite shifts to a lower temperature during the charging phase and the freezing point shifts to a higher temperature during the discharging phase when compared with the pure stearic acid. The experimental results show that the addition of MWCNT can improve the thermal conductivity of stearic acid effectively, but it also weakens the natural convection of stearic acid in liquid state. In comparison with the pure stearic acid, the charging rate can be decreased by about 50% while the discharging rate can be improved by about 91% respectively by using the SA/5.0% MWCNT nanocomposite. It appears that the MWCNT is a promising candidate for enhancing the heat transfer performance of latent heat thermal energy storage system. - Highlights: • A nanocomposite made of stearic acid and multi-walled carbon nanotube is prepared for thermal energy storage application. • Effects of multi-walled carbon nanotube on the thermal performance of the nanocomposite are investigated. • Multi-walled carbon nanotube enhances the thermal conductivity but weakens the natural convection of stearic acid. • Discharging/charging rates of stearic acid are increased/decreased by using multi-walled carbon nanotube

Carbon-13 kinetic isotope effects in the decarbonylation of lactic acid of natural isotopic composition in phosphoric acid medium

International Nuclear Information System (INIS)

Zielinski, M.; Czarnota, G.; Papiernik-Zielinska, H.; Kasprzyk, G.; Gumolka, L.; Staedter, W.

1993-01-01

The 13 C kinetic isotope effect fractionation in the decarbonylation of lactic acid (LA) of natural isotopic composition by concentrated phosphoric acids (PA) and by 85% H 3 PO 4 has been studied in the temperature interval of 60-150 deg C. The values of the 13 C (1) isotope effects in the decarbonylation of lactic acid in 100% H 3 PO 4 , in pyrophosphoric acid and in more concentrated phosphoric acids are intermediate between the values calculated assuming that the C (1)- OH bond is broken in the rate-controlling step of dehydration and those calculated for rupture of the carbon-carbon bond in the transition state. In the temperature interval of 90-130 deg C the experimental 13 C fractionation factors determined in concentrated PA approach quite closely the 13 C fractionation corresponding to C (2)- C (1) bond scission. The 13 C (1) kinetic isotope effects in the decarbonylation of LA in 85% orthophosphoric acid in the temperature range of 110-150 deg C coincide with the 13 C isotope effects calculated assuming that the frequency corresponding to the C (1) -OH vibration is lost in the transition state of decarbonylation. A change of the mechanism of decarbonylation of LA in going from concentrated PA medium to 85% H 3 PO 4 has been suggested. A possible secondary 18 O and a primary 18 O kinetic isotope effect in decarbonylation of lactic acid in phosphoric acids media have been discussed, too. (author) 21 refs.; 3 tabs

Investigation of adsorption and inhibitive effect of acid red GRE (183 dye on the corrosion of carbon steel in hydrochloric acid media

Directory of Open Access Journals (Sweden)

M. Abd El-raouf

2015-09-01

Full Text Available The adsorption and corrosion inhibitive effect of acid red GRE (183 dye on carbon steel alloy in 1 M HCl solutions was studied using various techniques. Results of weight loss, Tafel polarization measurements and electrochemical impedance spectroscopy (EIS techniques show that this compound has fairly good inhibiting properties for steel corrosion in acidic bath; with efficiency around 96% at a concentration of 50 ppm. The inhibition is of a mixed anodic–cathodic nature. Factors affecting the corrosion process have been calculated and discussed. Acid red GRE (183 dye was shown to be an inhibitor in the acidic corrosion. Inhibition efficiency increased with acid red GRE (183 dye concentration but decreased with rise in temperature, corrosion inhibition is attributed to the adsorption of acid red GRE (183 dye on the carbon steel surface via a physical adsorption mechanism. Langmuir isotherm is found to provide an accurate description of the adsorption behavior of the investigated azo compound. The nature of the protective film was investigated using SEM and EDX techniques.

Retreatment of recanalized aneurysms after Y-stent-assisted coil embolization with double enterprise stents: case report and systematic review of the literature.

Science.gov (United States)

Kono, Kenichi; Shintani, Aki; Terada, Tomoaki

2014-01-01

It is necessary to consider possibility of recanalization and retreatment after coil embolization for cerebral aneurysms. There is concern that retreatment for recanalized aneurysms after Y-stent-assisted coil embolization may be difficult because of double stents, especially in Y-stents with double closed-cell stents owing to narrowed structures. However, no detailed reports of retreatment after Y-stent have been reported. Between July 2010 and June 2013, we treated four aneurysms with Y-stent-assisted coil embolization using Enterprise closed-cell stents. Recanalization occurred in one case (25%), and retreatment was performed. We easily navigated a microcatheter into the target portions of the aneurysm through the Y-stent and occluded the aneurysm with coils. Additionally, by systematically searching in PubMed, we found 105 cases of Y-stent-assisted coil embolization using Enterprise stents or Neuroform stents with more than 6 months of follow-up. Among them, retreatment was performed in 10 cases (9.5%). There were no significant differences in retreatment rates among different stent combinations (P=0.91; Fisher's exact test). In conclusion, navigation of a microcatheter into the aneurysm through the Y-stent with double Enterprise stents was feasible, and retreatment rates after Y-stent-assisted coiling may not depend on stent combinations.

Hillslope failure and paraglacial reworking of sediments in response to glacier retreat, Fox Valley, New Zealand.

Science.gov (United States)

McColl, Samuel T.; Fuller, Ian C.; Anderson, Brian; Tate, Rosie

2017-04-01

Climate and glacier fluctuations influence sediment supply to glacier forelands, which in turn influences down-valley hazards to infrastructure and tourism within glacier forelands. At Fox Glacier, one of New Zealand's most iconic and popular glaciers, rapid retreat has initiated a range of hillslope and valley floor responses, that present a cascade of hazards and changes that need to be carefully managed. Fox Glacier has retreated many kilometres historically, with 2.6 km of retreat since the mid-20th century, and a phase of rapid retreat of 50-340 m per year since 2009. To study the system response to past and ongoing glacial retreat at the Fox valley, morphological changes are being observed using time-lapse photography and the annual collection of high-resolution digital elevation models (DEMs) and orthophoto mosaics. The DEMs are being produced using Structure from Motion photogrammetry from UAV/RPAS and helicopter platforms, and are being used, along with manual ground surveying, to produce ground surface change models (DoDs; DEMs of Difference) and sediment budgets for the valley. Results from time-lapse photography and DoDs show that glacial retreat has initiated destabilisation and (mostly chronic) mass movement of surficial glacial sediments on the valley slopes near the glacier terminus. Alluvial fans farther down valley are actively growing, reworking glacial and landslide sediments from tributary catchments. These paraglacial sediments being delivered to the proglacial river from the glacier terminus and alluvial fans are driving aggradation of the valley floor of decimetres to metres per year and maintaining a highly dynamic braid plain. Valley floor changes also include the melting of buried dead ice, which are causing localised subsidence at the carpark and one of the alluvial fans. The unstable slopes and active debris fans, aggrading and highly active river channel, ground subsidence, add to the spectacle but also the hazards of the Fox valley

Processes controlling the retreat of the Isles Dernieres, a Louisiana barrier-island chain

Science.gov (United States)

Dingler, John R.; Reiss, Thomas E.

1991-01-01

The Isles Dernieres is a low-lying, transgressive barrier-island chain situated about 150 km west of the modern Mississippi delta. Much of the Isles Dernieres consists of highly dissected salt-marsh muds that lie at or slightly above sea level and are covered by a veneer of sand along the shoreline facing the Gulf of Mexico. Maximum berm elevations are generally less than 1.5 m above mean sea level. Since the mid-1800s, the initial island has been fragmented into four islands, and the beach face has retreated landward at a rate of more than 10 m/yr. The dominant processes controlling degradation of the chain are cold fronts that pass through the area several times each year and occasional hurricanes. Beach surveys over a 2-year period on the Isles Dernieres document irreversible beach-face retreat in conjunction with multiple cold fronts and one major hurricane (Gilbert). Although both the hurricane and the cold fronts caused the island to erode, the erosional patterns of the two storm types differed from each other. During the two years, over 60 cold fronts collectively caused about 37 m of beach-face retreat, whereas Gilbert itself produced more than 40 m of retreat. A major difference between the two storm types was in the percentage of washover sand produced by each. Commonly, the cold fronts did not create enough of a storm surge to overtop the berm, so most of the material removed from the beach face must have moved offshore or alongshore. Gilbert, in contrast, inundated the study site, and essentially all the sand removed from the beach face moved to the backshore.

Carbon-11 and Fluorine-18 Labeled Amino Acid Tracers for Positron Emission Tomography Imaging of Tumors

Science.gov (United States)

Sun, Aixia; Liu, Xiang; Tang, Ganghua

2017-12-01

Tumor cells have an increased nutritional demand for amino acids(AAs) to satisfy their rapid proliferation. Positron-emitting nuclide labeled AAs are interesting probes and are of great importance for imaging tumors using positron emission tomography (PET). Carbon-11 and fluorine-18 labeled AAs include the [1-11C] amino acids, labeling alpha-C- amino acids, the branched-chain of amino acids and N-substituted carbon-11 labeled amino acids. These tracers target protein synthesis or amino acid(AA) transport, and their uptake mechanism mainly involves AA transport. AA PET tracers have been widely used in clinical settings to image brain tumors, neuroendocrine tumors, prostate cancer, breast cancer, non–small cell lung cancer (NSCLC) and hepatocellular carcinoma. This review focuses on the fundamental concepts and the uptake mechanism of AAs, AA PET tracers and their clinical applications.

Preliminary study on preparation of BCNO phosphor particles using citric acid as carbon source

Energy Technology Data Exchange (ETDEWEB)

Nuryadin, Bebeh W.; Pratiwi, Tripuspita; Faryuni, Irfana D.; Iskandar, Ferry, E-mail: ferry@fi.itb.ac.id; Abdullah, Mikrajuddin; Khairurrijal [Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Ganesha 10 Bandung, Indonesia 40132 (Indonesia); Ogi, Takashi; Okuyama, Kikuo [Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi Hiroshima, Japan 739-8527 (Japan)

2015-04-16

A citric acid was used as a carbon source in the preparation of boron carbon oxy-nitride (BCNO) phosphor particles by a facile process. The preparation process was conducted at relatively low temperature 750 °C and at ambient pressure. The prepared BCNO phosphors showed a high photoluminescence (PL) performance at peak emission wavelength of 470 nm under excitation by a UV light 365 nm. The effects of carbon/boron and nitrogen/boron molar ratios on the PL properties were also investigated. The result showed that the emission spectra with a wavelength peak ranging from 444 nm to 496 nm can be obtained by varying carbon/boron ratios from 0.1 to 0.9. In addition, the observations showed that the BCNO phosphor material has two excitation peaks located at the 365 nm (UV) and 420 nm (blue). Based on these observations, we believe that the citric acid derived BCNO phosphor particles can be a promising inexpensive material for phosphor conversion-based white LED.

Adsorption of nucleic acid bases and amino acids on single-walled carbon and boron nitride nanotubes: a first-principles study.

Science.gov (United States)

Zheng, Jiaxin; Song, Wei; Wang, Lu; Lu, Jing; Luo, Guangfu; Zhou, Jing; Qin, Rui; Li, Hong; Gao, Zhengxiang; Lai, Lin; Li, Guangping; Mei, Wai Ning

2009-11-01

We study the adsorptions of nucleic acid bases adenine (A), cytosine (C), guanine (G), thymine (T), and uracil (U) and four amino acids phenylalanine, tyrosine, tryptophan, alanine on the single-walled carbon nanotubes (SWCNTs) and boron nitride nanotubes (SWBNNTs) by using density functional theory. We find that the aromatic content plays a critical role in the adsorption. The adsorptions of nucleic acid bases and amino acids on the (7, 7) SWBNNT are stronger than those on the (7, 7) SWCNT. Oxidative treatment of SWCNTs favors the adsorption of biomolecules on nanotubes.

Summary of the RHIC Retreat 2008

Energy Technology Data Exchange (ETDEWEB)

Pilat,F.; Brennan, M.; Brown, K.; Fischer, W.; Montag, C.

2008-08-01

The main goal of the RHIC Retreat is to review last run's performance and prepare for the next. As always though we also discussed the longer term goals and plans for the facility to put the work in perspective and in the right priority. A straw-man plan for the facility was prepared for the DOE that assumes 30 cryoweek and running 2 species per year. The plan outlines RHIC operations for 2008-2012 and integrates well accelerator and detector upgrades to optimize the physics output with high luminosities. The plans includes guidance from the PAC and has been reviewed by DOE.

Stable carbon isotopic compositions of low-molecular-weight dicarboxylic acids, glyoxylic acid and glyoxal in tropical aerosols: implications for photochemical processes of organic aerosols

Directory of Open Access Journals (Sweden)

Stelyus L. Mkoma

2014-10-01

Full Text Available Tropical aerosols of PM2.5 and PM10 were collected at a rural site in Morogoro, Tanzania (East Africa, and analysed for stable carbon isotopic composition (δ13C of dicarboxylic acids (C2–C9, glyoxylic acid (ωC2 and glyoxal (Gly using gas chromatography/isotope ratio mass spectrometer. PM2.5 samples showed that δ13C of oxalic (C2 acid are largest (mean, −18.3±1.7‰ followed by malonic (C3, −19.6±1.0‰ and succinic (C4, −21.8±2.2‰ acids, whereas those in PM10 are a little smaller: −19.9±3.1‰ (C2, −20.2±2.7‰ (C3 and −23.3±3.2‰ (C4. The δ13C of C2–C4 diacids showed a decreasing trend with an increase in carbon numbers. The higher δ13C values of oxalic acid can be explained by isotopic enrichment of 13C in the remaining C2 due to the atmospheric decomposition of oxalic acid or its precursors. δ13C of ωC2 and Gly that are precursors of oxalic acid also showed larger values (mean, −22.5‰ and −20.2‰, respectively in PM2.5 than those (−26.7‰ and −23.7‰ in PM10. The δ13C values of ωC2 and Gly are smaller than those of C2 in both PM2.5 and PM10. On the other hand, azelaic acid (C9; mean, −28.5‰ is more depleted in 13C, which is consistent with the previous knowledge; that is, C9 is produced by the oxidation of unsaturated fatty acids emitted from terrestrial higher plants. A significant enrichment of 13C in oxalic acid together with its negative correlations with relative abundance of C2 in total diacids and ratios of water-soluble organic carbon and organic carbon further support that a photochemical degradation of oxalic acid occurs during long-range transport from source regions.

In vitro study of the effect of a dentifrice containing 8% arginine, calcium carbonate, and sodium monofluorophosphate on acid-softened enamel.

Science.gov (United States)

Rege, Aarti; Heu, Rod; Stranick, Michael; Sullivan, Richard J

2014-01-01

To investigate the possible mode of action of a dentifrice containing 8% arginine and calcium carbonate (Pro-Argin Technology), and sodium monofluorophosphate in delivering the benefits of preventing acid erosion and rehardening acid-softened enamel. The surfaces of acid-softened bovine enamel specimens were evaluated after application of a dentifrice containing 8% arginine, calcium carbonate, and sodium monofluorophosphate in vitro. Scanning Electron Microscopy (SEM), Electronic Spectrometry for Chemical Analysis (ESCA), and Secondary Ion Mass Spectrometry (SIMS) were used to characterize the enamel surfaces. Exposure of pristine enamel surfaces to citric acid resulted in clear roughening of the surface. Multiple applications of a dentifrice containing 8% arginine, calcium carbonate, and sodium monofluorophosphate to the surface of the enamel resulted in the disappearance of the microscopic voids observed by SEM as a function of treatment applications. The ESCA analysis demonstrated that both the nitrogen and carbonate levels increased as the number of treatments increased, which provides evidence that arginine and calcium carbonate were bound to the surface. Observance of arginine's signature mass fragmentation pattern by SIMS analysis confirmed the identity of arginine on the enamel surface. A series of in vitro experiments has demonstrated a possible mode of action by which a dentifrice containing 8% arginine, calcium carbonate, and sodium monofluorophosphate delivers the benefits of preventing acid erosion and rehardening acid-softened enamel. The combination of arginine and calcium carbonate adheres to the enamel surface and helps to fill the microscopic gaps created by acid, which in turn helps repair the enamel and provides a protective coating against future acid attacks.

Titration of Monoprotic Acids with Sodium Hydroxide Contaminated by Sodium Carbonate.

Science.gov (United States)

Michalowski, Tadeusz

1988-01-01

Discusses the effects of using carbon dioxide contaminated sodium hydroxide solution as a titrant for a solution of a weak monoprotic acid and the resulting distortion of the titration curve in comparison to one obtained when an uncontaminated titrant is used. (CW)

The erosion of carbonate stone by acid rain: Laboratory and field investigations

Science.gov (United States)

Baedecker, P.A.; Reddy, M.M.

1993-01-01

One of the goals of research on the effects of acidic deposition on carbonate stone surfaces is to define the incremental impact of acidic deposition relative to natural weathering processes on the rate of carbonate stone erosion. If rain that impacts carbonate stone surfaces is resident on the surface long enough to approach chemical equilibrium, the incremental effect of hydrogen ion is expected to be small (i.e., 6% for a rain of pH 4.0). Under nonequilibrium (i.e., high flow rate) conditions, kinetic considerations suggest that the incremental effect of hydrogen ion deposition could be quite significant. Field run-off experiments involving the chemical analysis of rain collected from inclined stone slabs have been used to evaluate stone dissolution processes under ambient conditions of wet and dry deposition of acidic species. The stoichiometry of the reaction of stone with hydrogen ion is difficult to define from the field data due to scatter in the data attributed to hydrodynamic effects. Laboratory run-off experiments show that the stoichiometry is best defined by a reaction with H+ in which CO2 is released from the system. The baseline effect caused by water in equilibrium with atmospheric CO2 is identical in the field and in laboratory simulation. The experiments show that the solutions are close enough to equilibrium for the incremental effect of hydrogen ion to be minor (i.e., 24% for marble for a rain of pH 4.0) relative to dissolution due to water and carbonic acid reactions. Stone erosion rates based on physical measurement are approximately double the recession rates that are due to dissolution (estimated from the observed calcium content of the run-off solutions). The difference may reflect the loss of granular material not included in recession estimates based on the run-off data. Neither the field nor the laboratory run-off experiments indicate a pH dependence for the grain-removal process.

Stability of therapeutic retreatment of corneal wavefront customized ablation with the SCHWIND CAM: 4-year data.

Science.gov (United States)

Aslanides, Ioannis M; Kolli, Sai; Padroni, Sara; Padron, Sara; Arba Mosquera, Samuel

2012-05-01

To evaluate the long-term outcomes of aspheric corneal wavefront ablation profiles for excimer laser retreatment. Eighteen eyes that had previously undergone LASIK or photorefractive keratectomy (PRK) were retreated with LASIK using the corneal wavefront ablation profile. Custom Ablation Manager (SCHWIND eye-tech-solutions, Kleinostheim, Germany) software and the ESIRIS flying spot excimer laser system (SCHWIND) were used to perform the ablations. Refractive outcomes and wavefront data are reported up to 4 years after retreatment. Pre- and postoperative data were compared with Student t tests and (multivariate) correlation tests. P<.05 was considered statistically significant. A bilinear correlation of various postoperative wavefront aberrations versus planned correction and preoperative aberration was performed. Mean manifest refraction spherical equivalent (MRSE) before retreatment was -0.38±1.85 diopters (D) and -0.09±0.22 D at 6 months and -0.10±0.38 D at 4 years postoperatively. The reduction in MRSE was statistically significant at both postoperative time points (P<.005). Postoperative aberrations were statistically lower (spherical aberration P<.05; coma P<.005; root-mean-square higher order aberration P<.0001) at 4 years postoperatively. Distribution of the postoperative uncorrected distance visual acuity (P<.0001) and corrected distance visual acuity (P<.01) were statistically better than preoperative values. Aspheric corneal wavefront customization with the ESIRIS yields visual, optical, and refractive results comparable to those of other wavefront-guided customized techniques for the correction of myopia and myopic astigmatism. The corneal wavefront customized approach shows its strength in cases where abnormal optical systems are expected. Systematic wavefront customized corneal ablation appears safe and efficacious for retreatment cases. Copyright 2012, SLACK Incorporated.

Hydrodeoxygenation of phenols as lignin models under acid-free conditions with carbon-supported platinum catalysts.

Science.gov (United States)

Ohta, Hidetoshi; Kobayashi, Hirokazu; Hara, Kenji; Fukuoka, Atsushi

2011-11-28

Carbon-supported Pt catalysts are highly active and reusable for the aqueous-phase hydrodeoxygenation of phenols as lignin models without adding any acids. It is suggested that Pt/carbon facilitates the hydrogenation of phenols and the hydrogenolysis of the resulting cyclohexanols.

Amino acids interacting with defected carbon nanotubes: ab initio calculations

Directory of Open Access Journals (Sweden)

M. Darvish Ganji

2016-09-01

Full Text Available The adsorption of a number of amino acids on a defected single-walled carbon nanotube (SWCNT is investigated by using the density-functional theory (DFT calculations. The adsorption energies and equilibrium distances are calculated for various configurations such as amino acid attaching to defect sites heptagon, pentagon and hexagon in defective tube and also for several molecular orientations with respect to the nanotube surface. The results showed that amino acids prefer to be physisorbed on the outer surface of the defected nanotube with different interaction strength following the hierarchy histidine > glycine > phenylalanine > cysteine. Comparing these findings with those obtained for perfect SWCNTs reveals that the adsorption energy of the amino acids increase for adsorption onto defected CNTs. The adsorption nature has also been evaluated by means of electronics structures analysis within the Mulliken population and DOS spectra for the interacting entities.

Amino acid assisted dehalogenation of carbon tetrachloride by green rust

DEFF Research Database (Denmark)

Yin, Weizhao; Strobel, Bjarne W.; Hansen, Hans Chr. Bruun

2017-01-01

that reduce the formation of toxic by-products such as chloroform (CF). In this study, carbon tetrachloride (CT) dehalogenation by the chloride form of GR (GRCl) was tested in presence of glycine (GLY) and other selected amino acids. GLY, alanine (ALA) or serine (SER) all resulted in remarkable suppression...... of CF formation with only ~ 10% of CF recovery while sarcosine (SAR) showed insignificant effects. For two non-amino acid buffers, TRIS had little effect while HEPES resulted in a 40 times lower rate constant compared to experiments where no buffer was added. The FeII complexing properties of the amino...... acids and buffers caused variable extents of GRCl dissolution which was linearly correlated with CF suppression and dehalogenation rate. We hypothesize that the CF suppression seen for amino acids is caused by stabilization of carbene intermediates via the carbonyl group. Different effects on CF...

Variability of onset and retreat of the rainy season in mainland China and associations with atmospheric circulation and sea surface temperature

Science.gov (United States)

Cao, Qing; Hao, Zhenchun; Shao, Quanxi; Hao, Jie; Nyima, Tsring

2018-02-01

Precipitation plays an important role in both environment and human society and is a significant factor in many scientific researches such as water resources, agriculture and climate impact studies. The onset and retreat of rainy season are useful features to understand the variability of precipitation under the influence of climate change. In this study, the characteristics of onset and retreat in mainland China are investigated. The multi-scale moving t-test was applied to determine rainy season and K-means cluster analysis was used to divide China into sub-regions to better investigate rainy season features. The possible linkage of changing characteristics of onset and retreat to climate factors were also explored. Results show that: (1) the onset started from middle March in the southeast of China to early June in the northwest and rainy season ended earliest in the northwest and southeast while the central China had the latest retreat; (2) Delayed onset and advanced retreat over time were observed in many parts of China, together with overall stable or increased rainy-season precipitation, would likely lead to higher probability of flooding; (3) The onset (retreat) was associated with the increased (decreased) number of cyclones in eastern China and anticyclone near the South China Sea. Delayed onset, and advanced retreat were likely related to cold and warm sea surface temperature (SST) in the conventional El Niño-Southern Oscillation (ENSO) regions, respectively. These results suggest that predictability of rainy season can be improved through the atmospheric circulation and SST, and help water resources management and agricultural planning.

Radial Flow Effects On A Retreating Rotor Blade

Science.gov (United States)

2014-05-01

birds , marine life and even insect wings. In some cases such as helicopters, wind turbines and compres- sors, dynamic stall becomes the primary...on dynamic stall and reverse flow as applied to a helicopter rotor in forward flight and a wind turbine operating at a yaw angle. While great...occurring on a retreating blade with a focus on dynamic stall and reverse flow as applied to a helicopter rotor in forward flight and a wind turbine

Effects of inherent/enhanced solid acidity and morphology of diatomite templates on the synthesis and porosity of hierarchically porous carbon.

Science.gov (United States)

Liu, Dong; Yuan, Peng; Tan, Daoyong; Liu, Hongmei; Fan, Mingde; Yuan, Aihua; Zhu, Jianxi; He, Hongping

2010-12-21

The inherent or enhanced solid acidity of raw or activated diatomite is found to have significant effects on the synthesis of hierarchically porous diatomite-templated carbon with high surface area and special porous structure. The solid acidity makes raw/activated diatomite a catalyst for the generation of porous carbon, and the porous parameters of the carbon products are strongly dependent on the solid acidity of diatomite templates. The morphology of diatomite also dramatically affects the textural structure of porous carbon. Two types of macroporous structures in the carbon product, the partially solid pillars and the ordered hollow tubes, derive from the replication of the central and the edge pores of diatom shell, respectively. The hierarchically porous carbon shows good capability for the adsorption of solvent naphtha and H(2), enabling potential applications in adsorption and gas storage.

[Effects of carbon and nitrogen sources on 5-keto-gluconic acid production].

Science.gov (United States)

Tan, Zhilei; Wang, Hongcui; Wei, Yuqiao; Li, Yanyan; Zhong, Cheng; Jia, Shiru

2014-01-01

Gluconobacter oxydans is known to oxidize glucose to gluconic acid (GA), and subsequently, to 2-keto-gluconic acid (2KGA) and 5-keto-gluconic acid (5KGA), while 5KGA can be converted to L-(+)-tartaric acid. In order to increase the production of 5KGA, Gluconobacter oxydans HGI-1 that converts GA to 5KGA exclusively was chosen in this study, and effects of carbon sources (lactose, maltose, sucrose, amylum and glucose) and nitrogen sources (yeast extract, fish meal, corn steep liquor, soybean meal and cotton-seed meal) on 5KGA production were investigated. Results of experiment in 500 mL shake-flask show that the highest yield of 5KGA (98.20 g/L) was obtained using 100 g/L glucose as carbon source. 5KGA reached 100.20 g/L, 109.10 g/L, 99.83 g/L with yeast extract, fish meal and corn steep liquor as nitrogen source respectively, among which the optimal nitrogen source was fish meal. The yield of 5KGA by corn steep liquor is slightly lower than that by yeast extract. For the economic reason, corn steep liquor was selected as nitrogen source and scaled up to 5 L stirred-tank fermentor, and the final concentration of 5KGA reached 93.80 g/L, with its maximum volumetric productivity of 3.48 g/(L x h) and average volumetric productivity of 1.56 g/(L x h). The result obtained in this study showed that carbon and nitrogen sourses for large-scale production of 5KGA by Gluconobacter oxydans HGI-1 were glucose and corn steep liquor, respectively, and the available glucose almost completely (85.93%) into 5KGA.

Effectiveness of ProTaper, D-RaCe, and Mtwo retreatment files with and without supplementary instruments in the removal of root canal filling material.

Science.gov (United States)

Marques da Silva, B; Baratto-Filho, F; Leonardi, D P; Henrique Borges, A; Volpato, L; Branco Barletta, F

2012-10-01

To assess the efficacy of different retreatment rotary files in removing gutta-percha and endodontic sealer from canals. Ninety straight single-rooted premolars were prepared up to a size 30 and filled with gutta-percha and sealer and then randomly assigned to six retreatment groups (n = 15). Groups I, III, and V were retreated using rotary systems ProTaper Universal Retreatment (PTUR), D-RaCe, and Mtwo Retreatment, respectively. Groups II, IV, and VI were retreated using the additional instruments F4, size 40, .04 taper RaCe, and size 40, .04 taper Mtwo, respectively. The roots were split vertically, and images of the halves were obtained using a high-resolution scanner and evaluated with AutoCAD software to calculate the percentage of residual material. Data were analyzed with Kruskal-Wallis and Student-Newman-Keuls tests using a 5% significance cutoff (P 0.05) between groups when additional instruments were used. The percentage of residual material was lowest in the PTUR group and was statistically significant only when compared to the D-RaCe system (P = 0.0038). All root canals had residual filling material after retreatment even when additional instruments were used. © 2012 International Endodontic Journal.

Recovery of calcium carbonate from steelmaking slag and utilization for acid mine drainage pre-treatment

CSIR Research Space (South Africa)

Mulopo, J

2012-06-01

Full Text Available The conversion of steelmaking slag (a waste product of the steelmaking process) to calcium carbonate (CaCO3) was tested using hydrochloric acid, ammonium hydroxide and carbon dioxide via a pH-swing process. Batch reactors were used to assess...

Carbonic acid ionization and the stability of sodium bicarbonate and carbonate ion pairs to 200 °C - A potentiometric and spectrophotometric study

Science.gov (United States)

Stefánsson, Andri; Bénézeth, Pascale; Schott, Jacques

2013-11-01

Carbonic acid ionization and sodium bicarbonate and carbonate ion pair formation constants have been experimentally determined in dilute hydrothermal solutions to 200 °C. Two experimental approaches were applied, potentiometric acid-base titrations at 10-60 °C and spectrophotometric pH measurements using the pH indicators, 2-napthol and 4-nitrophenol, at 25-200 °C. At a given temperature, the first and second ionization constants of carbonic acid (K1, K2) and the ion pair formation constants for NaHCO(aq)(K) and NaCO3-(aq)(K) were simultaneously fitted to the data. Results of this study compare well with previously determined values of K1 and K2. The NaHCO(aq) and NaCO3-(aq) ion pair formation constants vary between 25 and 200 °C having values of logK=-0.18 to 0.58 and logK=1.01 to 2.21, respectively. These ion pairs are weak at low-temperatures but become increasingly important with increasing temperature under neutral to alkaline conditions in moderately dilute to concentrated NaCl solutions, with NaCO3-(aq) predominating over CO32-(aq) in ⩾0.1 M NaCl solution at temperatures above 100 °C. The results demonstrate that NaCl cannot be considered as an inert (non-complexing) electrolyte in aqueous carbon dioxide containing solutions at elevated temperatures.

Possible role for abscisic acid in regulation of photosynthetic and photorespiratory carbon metabolism in barley leaves

International Nuclear Information System (INIS)

Popova, L.P.; Tsonev, T.D.; Vaklinova, S.G.

1987-01-01

The influence of abscisic acid (ABA) on carbon metabolism, rate of photorespiration, and the activity of the photorespiratory enzymes ribulose bisphosphate oxygenase and glycolate oxidase in 7-day-old barley seedlings (Hordeum vulgare L. var. Alfa) was investigated. Plants treated with ABA had enhanced incorporation of labeled carbon from 14 CO 2 into glycolic acid, glycine, and serine, while 14 C incorporation into 3-phosphoglyceric acid and sugarphosphate esters was depressed. Parallel with this effect, treated plants showed a rise in activity of RuBP oxygenase and glycolic acid oxidase. The rate of photorespiration was increased twofold by ABA treatment at IO -6 molar while the CO 2 -compensation point increased 46% and stomatal resistance increased more than twofold over control plants

Effect of Endodontic Retreatment on Push-out Bond Strength and Quality of Fiber Postbonding Interface of Resin Cements.

Science.gov (United States)

Pelegrine, Rina Andréa; Paulillo, Luís Alexandre Maffei Sartini; Kato, Augusto Shoji; Fontana, Carlos Eduardo; Pinheiro, Sérgio Luiz; De Martin, Alexandre Sigrist; Bueno, Carlos Eduardo da Silveira

2016-01-01

The aim of this study is to evaluate the impact of endodontic retreatment on push-out bond strength and dentin interface of two resin cements used for fiber postcementation during endodontic retreatment. The root canals of 40 extracted human canines were prepared, obturated and divided into four groups (n = 10). Gutta-percha was partially removed and fiber posts were immediately cemented in groups 1 and 2 using Panavia F with ED Primer and RelyX™ U200, respectively. In groups 3 and 4, the root canal access was sealed with temporary restorative cement, specimens were stored for 30 days, endodontically retreated, and fiber posts were cemented using the resin cements applied to groups 1 and 2, respectively. Push-out tests and scanning electron microscopy analyses of different areas were performed. Data from push-out bond strengths were analyzed by one-way analysis of variance and Tukey's tests. Higher bond strength values were detected in the apical third for group 1 than group 3 (p 0.05). Comparisons between different thirds in the same group revealed a higher bond strength in the apical third for group 1. Scanning electron microscopy showed formation of hybrid layer and extensive resin tags in group 1. No hybrid layer was observed in groups 2 and 4. Endodontic retreatment had adverse effects on the push-out bond strength and dentinal interface of Panavia F with ED Primer when used for fiber postcementation specifically in the apical third, but not on RelyX™ U200. A significant interaction was detected between endodontic retreatment and resin cement, which indicated that endodontic retreatment might adversely affect the push-out bond strength and dentinal interface of Panavia F with ED Primer when used for fiber postcementation specifically in the apical third.

Monitoring the functionalization of single-walled carbon nanotubes with chitosan and folic acid by two-dimensional diffusion-ordered nmr spectroscopy

DEFF Research Database (Denmark)

Castillo, John J.; Torres, Mary H.; Molina, Daniel R.

2012-01-01

A conjugate between single-walled carbon nanotubes, chitosan and folic acid has been prepared. It was characterized by diffusion ordered two-dimensional hydrogen-1 nuclear magnetic resonance and hydrogen-1 nuclear magnetic resonance spectroscopy which revealed the presence of a conjugate that was......A conjugate between single-walled carbon nanotubes, chitosan and folic acid has been prepared. It was characterized by diffusion ordered two-dimensional hydrogen-1 nuclear magnetic resonance and hydrogen-1 nuclear magnetic resonance spectroscopy which revealed the presence of a conjugate...... that was generated by the linkage between the carboxyl moiety of the folic acid and the amino group of the chitosan, which in turn was non-covalently bound to the single-walled carbon nanotubes. The obtained diffusion coefficient values demonstrated that free folic acid diffused more rapidly than the folic acid...... conjugated to single-walled carbon nanotubes-chitosan. The values of the proton signal of hydrogen-1 nuclear magnetic resonance spectroscopy and two-dimensional hydrogen-1 nuclear magnetic resonance spectroscopy further confirmed that the folic acid was conjugated to the chitosan, wrapping the single...

Bias-dependent amino-acid-induced conductance changes in short semi-metallic carbon nanotubes

International Nuclear Information System (INIS)

Abadir, G B; Walus, K; Pulfrey, D L

2010-01-01

We study the interaction between short semi-metallic carbon nanotubes and different amino acids using molecular dynamics and ab initio (density functional theory/non-equilibrium Green's function) simulations. We identify two different mechanisms of nanotube conductance change upon adsorption of amino acids: one due to the change of the coordinates of the nanotube arising from van der Waals forces of interaction with the adsorbed amino acid; and one due to electrostatic interactions, which appear only in the case of charged amino acids. We also find that the transport mechanism and the changes in the conductance of the tube upon amino acid adsorption are bias dependent.

Comparison of 5468 retreatments after laser in situ keratomileusis by lifting the flap or performing photorefractive keratectomy on the flap.

Science.gov (United States)

Ortega-Usobiaga, J; Llovet-Osuna, F; Katz, T; Djodeyre, M R; Druchkiv, V; Bilbao-Calabuig, R; Baviera, J

2018-02-01

To assess visual outcomes of retreatment after laser in situ keratomileusis (LASIK) by lifting the flap or performing photorefractive keratectomy (PRK) on the flap, as well as to establish whether there was an increased risk of epithelial ingrowth (EIG) when LASIK and lifting of the flap are separated by a long time interval and to determine the incidence of corneal haze after PRK. Retrospective study of 4077 patients (5468 eyes) who underwent LASIK and subsequent retreatment were reviewed in order to study their visual results and identify cases of EIG and corneal haze. Enhancements included 5196 eyes from 3876 patients that were retreated by lifting the flap, and 272 eyes from 201 patients that were retreated by PRK on the flap. No statistically significant differences were found between the retreatments in terms of predictability, efficacy, and safety. A total of 704 cases of EIG were found after lifting the flap, for which surgical cleansing was necessary in 70. Surgical cleansing decreased the efficacy index when compared with patients with EIG who did not need cleansing (P=.01). Differences in terms of safety and predictability were not statistically significant. The incidence of corneal haze after ablation of the surface of the previous flap was 14.34%, although none of these cases were clinically relevant. Visual outcomes were similar between patients who were retreated by lifting the flap and those who underwent PRK. The incidence of EIG when the flap was lifted was 13.55%. The incidence of EIG increases with the time elapsed between the primary procedure and retreatment. Copyright © 2017 Sociedad Española de Oftalmología. Publicado por Elsevier España, S.L.U. All rights reserved.

Reactive extraction of carboxylic acids from apolar hydrocarbons using aqueous solutions of sodium hydrogen carbonate with back-recovery using carbon dioxide under pressure

NARCIS (Netherlands)

Kuzmanovic, B.; Kuipers, N.J.M.; de Haan, A.B.; Kwant, Gerard

2005-01-01

A combination of using an aqueous solution of sodium hydrogen carbonate for forward-extraction of carboxylic acids from a dilute apolar organic solvent, and carbon dioxide under pressure for its back-recovery, is studied. Used in combination, these two steps might provide a technique for the

Writing Retreat Increases Productivity And Community For Women Geoscientists

Science.gov (United States)

O'Connell, S.; Holmes, M.

2011-12-01

Five, weeklong geoscientist writing retreats have been completed with an NSF ADANCE PAID grant. During the five nights and four and a half days, eight to twenty-four academics have gathered in a rural setting outside of Boston to get to focus on writing papers and proposals while getting to know each other. Participants range in age and experience from graduate students to emeritus professors. Over twenty papers and proposals acknowledge their production, in part to this writing retreat. Impact extends beyond papers as informal mentoring and discussions at meals and in the evenings centers on succeeding in academia. Research and teaching are foremost in the conversation. Post-docs learn strategies for applying for jobs and grants, and senior professors discuss strategies for working with academic administrations, running departments and mentoring students. They also learn new technologies and perspectives from younger participants. Particularly helpful are discussions on work-life balance. Networking opportunities extend beyond the retreat as participants join each other at their home institutions to give seminars, develop research projects and mentor each other's students. All weeks follow the same format. Participants arrive Sunday and meet during an evening welcome reception. Monday is devoted to writing. Tuesday a writing coach is available. In the morning, using examples from the scientific literature, she discusses strategies and techniques for writing clearly at a group session. During the afternoon, participants work with the coach individually or in small groups to improve their own writing projects. Wednesday evening a skill session is offered on a topic of interest. These have included undergraduate research, NSF funding, productive techniques for dealing with conflict, and generational characteristics and attitudes, which can hamper communication. A Thursday evening wrap-up session prepares participants for Friday's departure. We believe that this model

Prolonged acid rain facilitates soil organic carbon accumulation in a mature forest in Southern China.

Science.gov (United States)

Wu, Jianping; Liang, Guohua; Hui, Dafeng; Deng, Qi; Xiong, Xin; Qiu, Qingyan; Liu, Juxiu; Chu, Guowei; Zhou, Guoyi; Zhang, Deqiang

2016-02-15

With the continuing increase in anthropogenic activities, acid rain remains a serious environmental threat, especially in the fast developing areas such as southern China. To detect how prolonged deposition of acid rain would influence soil organic carbon accumulation in mature subtropical forests, we conducted a field experiment with simulated acid rain (SAR) treatments in a monsoon evergreen broadleaf forest at Dinghushan National Nature Reserve in southern China. Four levels of SAR treatments were set by irrigating plants with water of different pH values: CK (the control, local lake water, pH ≈ 4.5), T1 (water pH=4.0), T2 (water pH=3.5), and T3 (water pH=3.0). Results showed reduced pH measurements in the topsoil exposed to simulated acid rains due to soil acidification. Soil respiration, soil microbial biomass and litter decomposition rates were significantly decreased by the SAR treatments. As a result, T3 treatment significantly increased the total organic carbon by 24.5% in the topsoil compared to the control. Furthermore, surface soil became more stable as more recalcitrant organic matter was generated under the SAR treatments. Our results suggest that prolonged acid rain exposure may have the potential to facilitate soil organic carbon accumulation in the subtropical forest in southern China. Copyright © 2015 Elsevier B.V. All rights reserved.

[Etiology of combined inhalational hydrocyanic acid and carbon monoxide poisoning].

Science.gov (United States)

Sigrist, T; Dirnhofer, R

1979-01-01

A young man was found dead in a kitchen, that was partly burnt. Autopsy revealed, as cause of death, a combined intoxication following inhalation of carbon monoxide and hydrocyanic acid. Own investigations on the pyrolysis of pieces of furniture found in the kitchen (plastic plates containing melamine and plates containing formaldehyde) showed, that hydrocyanic acid was liberated through combustion of such substances and inhaled by the victim. The poisoning picture is discussed, and discussion includes especially considerations on the peculiar sensitivity of the brain toward the action of hydrocyanic acid and the relative insensitivity of the heart muscle. It is thought that the cause of such sensitivity difference lies in the physiological differences of the intracellular energy production. Finally the dangers of combustion gases developing from burning plastic materials are reemphasized.

Highly active carbon supported Pd cathode catalysts for direct formic acid fuel cells

Energy Technology Data Exchange (ETDEWEB)

Mikolajczuk-Zychora, A., E-mail: amikolajczuk@ichf.edu.pl [Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw (Poland); Borodzinski, A.; Kedzierzawski, P.; Mierzwa, B. [Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw (Poland); Mazurkiewicz-Pawlicka, M. [Faculty of Materials Science and Engineering, Warsaw University of Technology, Wołoska 141, 02-507 Warsaw (Poland); Faculty of Chemical and Process Engineering, Warsaw University of Technology, Warynskiego 1, Warsaw (Poland); Stobinski, L. [Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw (Poland); Faculty of Chemical and Process Engineering, Warsaw University of Technology, Warynskiego 1, Warsaw (Poland); Ciecierska, E. [Faculty of Materials Science and Engineering, Warsaw University of Technology, Wołoska 141, 02-507 Warsaw (Poland); Zimoch, A.; Opałło, M. [Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw (Poland)

2016-12-01

Highlights: • Palladium catalyst used on the cathode DFAFC is comparable to commercial platinum catalyst. • The treatment of carbon supports in nitric acid(V) increases the electrochemically available metal surface area and the catalytic activity in oxygen reduction reaction of catalysts. - Abstract: One of the drawbacks of low-temperature fuel cells is high price of platinum-based catalysts used for the electroreduction of oxygen at the cathode of the fuel cell. The aim of this work is to develop the palladium catalyst that will replace commonly used platinum cathode catalysts. A series of palladium catalysts for oxygen reduction reaction (ORR) were prepared and tested on the cathode of Direct Formic Acid Fuel Cell (DFAFC). Palladium nanoparticles were deposited on the carbon black (Vulcan) and on multiwall carbon nanotubes (MWCNTs) surface by reduction of palladium(II) acetate dissolved in ethanol. Hydrazine was used as a reducing agent. The effect of functionalization of the carbon supports on the catalysts physicochemical properties and the ORR catalytic activity on the cathode of DFAFC was studied. The supports were functionalized by treatment in nitric acid for 4 h at 80 °C. The structure of the prepared catalysts has been characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), transmission electron microscope (TEM) and cyclic voltammetry (CV). Hydrophilicity of the catalytic layers was determined by measuring contact angles of water droplets. The performance of the prepared catalysts has been compared with that of the commercial 20 wt.% Pt/C (Premetek) catalyst. The maximum power density obtained for the best palladium catalyst, deposited on the surface of functionalized carbon black, is the same as that for the commercial Pt/C (Premetek). Palladium is cheaper than platinum, therefore the developed cathode catalyst is promising for future applications.

Carbon monoxide is not responsible for the cigarette smokeinduced changes in the pulmonary metabolism of arachidonic acid and prostaglandin E2

International Nuclear Information System (INIS)

Maennistoe, J.; Puustinen, T.; Uotila, P.

1985-01-01

Cigarette smoke is known to interfere with the pulmonary metabolism of arachidomic acid and prostaglandin E 2 (PGE 2 ). We investigated the possible role of carbon monoxide in these cigarette smoke-infuced alterations. 4 C-Arachidonic acid (50 nmol) was indused into the pulmonary circulation of isolated perfused hamster lungs and the radioactive metabolites in the perfusion effluent, as well as the distribution of incorporated radioactive arachidonic acid within the lung lipids, were analysed. Carbon monoxide, added into the ventilatory air, had no effect on the oxidative metabolism of arachidonic acid or on the distribution of radioactive arachidonic acid within the lung. In addition, carbon monoxide had no effect on the metabolism of PGE 2 following infusion of 100 nmol of 14 C-PGE 2 into the rat pulmonary circulation. The present study suggests that carbon monoxide is not responsible for the cigarette smoke-induced changes in the pulmonary metabolism of arachidonic acid and PGE 2 . (author)

Efficient Production of N-Butyl Levulinate Fuel Additive from Levulinic Acid Using Amorphous Carbon Enriched with Oxygenated Groups

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Jinfan Yang

2018-01-01

Full Text Available The aim of this study was to develop an effective carbonaceous solid acid for synthesizing green fuel additive through esterification of lignocellulose-derived levulinic acid (LA and n-butanol. Two different sulfonated carbons were prepared from glucose-derived amorphous carbon (GC400 and commercial active carbon (AC400. They were contrastively studied by a series of characterizations (N2 adsorption, X-ray diffraction, elemental analysis, transmission electron microscopy, Fourier transform infrared spectroscopy and NH3 temperature programmed desorption. The results indicated that GC400 possessed stronger acidity and higher –SO3H density than AC400, and the amorphous structure qualified GC400 for good swelling capacity in the reaction solution. Assessment experiments showed that GC400 displayed remarkably higher catalytic efficiency than AC400 and other typical solid acids (HZSM-5, Hβ, Amberlyst-15 and Nafion-212 resin. Up to 90.5% conversion of LA and 100% selectivity of n-butyl levulinate could be obtained on GC400 under the optimal reaction conditions. The sulfonated carbon retained 92% of its original catalytic activity even after five cycles.

Comparison of cyclic fatigue resistance of three different rotary nickel-titanium instruments designed for retreatment.

Science.gov (United States)

Inan, Ugur; Aydin, Cumhur

2012-01-01

A number of rotary nickel-titanium (NiTi) systems have been developed to provide better, faster, and easier cleaning and shaping of the root canal system, and recently, rotary NiTi systems designed for root canal retreatment have been introduced. Because the main problem with the rotary NiTi files is fracture, the aim of this study was to compare the cyclic fatigue resistance of 3 different rotary NiTi systems designed for root canal retreatment. Total of 60 instruments of 3 different rotary NiTi systems designed for root canal retreatment were used in this study. Twenty R-Endo R3, 20 ProTaper D3, and 20 Mtwo R (Retreatment) 25.05 instruments were tested. Cyclic fatigue testing of instruments was performed by using a device that allowed the instruments to rotate freely inside an artificial canal. Each instrument was rotated until fracture occurred, and the number of cycles to fracture for each instrument was calculated. Representative samples were also evaluated under a scanning electron microscope to confirm the fracture was flexural. Data were analyzed by using 1-way analysis of variance test. R-Endo R3 instruments showed better cyclic fatigue resistance than ProTaper D3 and Mtwo R 25.05 instruments, and the difference was statistically significant (P instruments were more resistant to fatigue failure than ProTaper D3 and Mtwo R 25.05. Copyright © 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Understanding the corrosion inhibition of carbon steel and copper in sulphuric acid medium by amino acids using electrochemical techniques allied to molecular modelling methods

International Nuclear Information System (INIS)

Mendonça, Glaydson L.F.; Costa, Stefane N.; Freire, Valder N.; Casciano, Paulo N.S.; Correia, Adriana N.; Lima-Neto, Pedro de

2017-01-01

Highlights: • Corrosion inhibition of carbon steel and of copper by the amino acids was studied. • Inhibition efficiencies were experimentally achieved by electrochemical impedance. • DFT and Monte Carlo methods allowed correlating molecular properties with inhibition efficiency. • The corrosion inhibition followed the electron donation the electron-back donations process. - Abstract: Six amino acids were evaluated as corrosion inhibitors for carbon steel and copper in 0.5 mol L"−"1 H_2SO_4 solution by potentiodynamic polarization and electrochemical impedance techniques allied to Density Functional Theory (DFT) and Monte Carlo computations The corrosion inhibitor rankings were: Arg > Gln > Asn > Met > Cys > Ser, for copper, and Met > Cys > Ser > Arg > Gln > Asn, for carbon steel. The DFT approach failed to explain the corrosion inhibition rating based on the HOMO and LUMO energies of the isolated amino acid molecules, while the simpler classical Monte Carlo approach, performed considering the interaction energies between the corrosion inhibitor and the metallic substrate, was successful.

Recent glacier retreat and climate trends in Cordillera Huaytapallana, Peru

Science.gov (United States)

López-Moreno, J. I.; Fontaneda, S.; Bazo, J.; Revuelto, J.; Azorin-Molina, C.; Valero-Garcés, B.; Morán-Tejeda, E.; Vicente-Serrano, S. M.; Zubieta, R.; Alejo-Cochachín, J.

2014-01-01

We analyzed 19 annual Landsat Thematic Mapper images from 1984 to 2011 to determine changes of the glaciated surface and snow line elevation in six mountain areas of the Cordillera Huaytapallana range in Peru. In contrast to other Peruvian mountains, glacier retreat in these mountains has been poorly documented, even though this is a heavily glaciated area. These glaciers are the main source of water for the surrounding lowlands, and melting of these glaciers has triggered several outburst floods. During the 28-year study period, there was a 55% decrease in the surface covered by glaciers and the snowline moved upward in different regions by 93 to 157 m. Moreover, several new lakes formed in the recently deglaciated areas. There was an increase in precipitation during the wet season (October-April) over the 28-year study period. The significant increase in maximum temperatures may be related to the significant glacier retreat in the study area. There were significant differences in the wet season temperatures during El Niño (warmer) and La Niña (colder) years. Although La Niña years were generally more humid than El Niño years, these differences were not statistically significant. Thus, glaciers tended to retreat at a high rate during El Niño years, but tended to be stable or increase during La Niña years, although there were some notable deviations from this general pattern. Climate simulations for 2021 to 2050, based on the most optimistic assumptions of greenhouse gas concentrations, forecast a continuation of climate warming at the same rate as documented here. Such changes in temperature might lead to a critical situation for the glaciers of the Cordillera Huaytapallana, and may significantly impact the water resources, ecology, and natural hazards of the surrounding areas.

Roles of acidic functional groups of carbon fiber surfaces in enhancing interfacial adhesion behavior

International Nuclear Information System (INIS)

Park, Soo-Jin; Kim, Byung-Joo

2005-01-01

The gas phase ozone treatment was used as a method to bind acidic oxygen functional groups on carbon fiber surfaces. The ozone treatment on carbon fibers was varied with the ozone concentration and treatment time. Surface analyses of the carbon fibers before and after treatments were performed by FT-IR, X-ray photoelectron spectrometer (XPS), and dynamic contact angle measurements. Mechanical interfacial properties of the fibers/polymer composites were investigated by using critical stress intensity factor (K IC ) and critical energy release rate (G IC ) measurements. From the results of FT-IR and XPS, it was observed that the oxygen functional groups, such as -OH, O-C=O, C=O, and C-O, were attached on the carbon fiber surfaces after the ozone treatment. The mechanical interfacial properties of the composites also showed higher values than those of untreated composites. Ozone treatment is attributed to the increase of both the acidic functional groups and the degree of adhesion at interfaces between the fibers and polymeric resin in composites

Enriched surface acidity for surfactant-free suspensions of carboxylated carbon nanotubes purified by centrifugation

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Elizabeth I. Braun

2016-06-01

Full Text Available It is well known that surfactant-suspended carbon nanotube (CNT samples can be purified by centrifugation to decrease agglomerates and increase individually-dispersed CNTs. However, centrifugation is not always part of protocols to prepare CNT samples used in biomedical applications. Herein, using carboxylated multi-walled CNTs (cMWCNTs suspended in water without a surfactant, we developed a Boehm titrimetric method for the analysis of centrifuged cMWCNT suspensions and used it to show that the surface acidity of oxidized carbon materials in aqueous cMWCNT suspensions was enriched by ∼40% by a single low-speed centrifugation step. This significant difference in surface acidity between un-centrifuged and centrifuged cMWCNT suspensions has not been previously appreciated and is important because the degree of surface acidity is known to affect the interactions of cMWCNTs with biological systems.

Nitrate Activation of Cytosolic Protein Kinases Diverts Photosynthetic Carbon from Sucrose to Amino Acid Biosynthesis

Science.gov (United States)

Champigny, Marie-Louise; Foyer, Christine

1992-01-01

The regulation of carbon partitioning between carbohydrates (principally sucrose) and amino acids has been only poorly characterized in higher plants. The hypothesis that the pathway of sucrose and amino acid biosynthesis compete for carbon skeletons and energy is widely accepted. In this review, we suggest a mechanism involving the regulation of cytosolic protein kinases whereby the flow of carbon is regulated at the level of partitioning between the pathways of carbohydrate and nitrogen metabolism via the covalent modulation of component enzymes. The addition of nitrate to wheat seedlings (Triticum aestivum) grown in the absence of exogenous nitrogen has a dramatic, if transient, impact on sucrose formation and on the activities of sucrose phosphate synthase (which is inactivated) and phosphoenolpyruvate carboxylase (which is activated). The activities of these two enzymes are modulated by protein phosphorylation in response to the addition of nitrate, but they respond in an inverse fashion. Sucrose phosphate synthase in inactivated and phosphoenolpyruvate carboxylase is activated. Nitrate functions as a signal metabolite activating the cytosolic protein kinase, thereby modulating the activities of at least two of the key enzymes in assimilate partitioning and redirecting the flow of carbon away from sucrose biosynthesis toward amino acid synthesis. PMID:16653003

Postoperative Pain after Endodontic Retreatment Using Rotary or Reciprocating Instruments: A Randomized Clinical Trial.

Science.gov (United States)

Comparin, Daniel; Moreira, Edson Jorge Lima; Souza, Erick M; De-Deus, Gustavo; Arias, Ana; Silva, Emmanuel João Nogueira Leal

2017-07-01

The aim of this randomized clinical trial was to evaluate the influence of rotary or reciprocating retreatment techniques on the incidence, intensity, duration of postoperative pain, and medication intake. After power analysis calculations, 65 patients who needed endodontic retreatment were randomly assigned to 1 of 2 groups according to the instrumentation system used: Mtwo (VDW, Munich, Germany) or Reciproc (VDW). Retreatments were performed in a single visit by an endodontic specialist. Participants were asked to rate the incidence and intensity of the postoperative pain on a verbal rating scale 24, 48, and 72 hours after treatment. Patients were also asked to record the number of prescribed analgesic medication tablets (ibuprofen 400 mg) taken. A logistic regression analysis was used to assess both the incidence and duration of pain. Differences in the intensity of pain were analyzed using the ordinal (linear) chi-square test, and the Mann-Whitney U test was used to assess differences in the intake of analgesic medication between groups. No statistically significant difference was found among the 2 groups in relation to postoperative pain or analgesic medication intake at the 3 time points assessed (P > .05). Multivariate analysis showed a significantly higher incidence of pain after 24 hours when preoperative pain was present and a significantly longer duration of pain for men than women independently of the retreatment technique used. The reciprocating system and the continuous rotary system were found to be equivalent regarding the incidence, intensity, duration of postoperative pain, and intake of analgesic medication. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Electrochemical Sensor for Determination of Ascorbic Acid Using a 2-Chlorobenzoyl Ferrocene/Carbon Nanotube Paste Electrode

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Sayed Zia Mohammadi

2016-12-01

Full Text Available A chemically modified carbon paste electrode with 2-chlorobenzoyl ferrocene (2CBF and carbon nanotube (2CBFCNPE was employed to study the electrocatalytic oxidation of ascorbic acid in aqueous solution using cyclic voltammetry, square wave voltammetry and chronoamperometry. The diffusion coefficient (D = 1.42 × 10-6 cm2 s-1, and the kinetic parameter such as the catalytic rate constant (k = 3.7 × 10 3 M-1 s-1 of ascorbic acid oxidation at the surface of 2CBFCNPE were determined using electrochemical approaches. It has been found that under an optimum condition (pH 4.0, the oxidation of ascorbic acid at the surface of such an electrode occurs at a potential about 85 mV less positive than that of an unmodified carbon paste electrode. Applying square wave voltammetry, in phosphate buffer solution (PBS of pH 4.0, the oxidation current increases linearly with two concentration intervals of ascorbic acid, one is 1.0 × 10-7-2.5 × 10-6 M and the other is 2.5 × 10-6-7.0 × 10-5 M. Detection limit (3δ was obtained 64.0 nM. This method was also examined for determination of ascorbic acid in some real samples.

From networking to next-working: how an academic department "retreated" and advanced at the same time.

Science.gov (United States)

Yager, Joel; Kenna, Heather; Hantke, Mindy

2015-04-01

Department-wide retreats conducted at periods of transition can enrich and benefit academic departments in several ways. Here, the authors describe the organization, conduct, and immediate outcomes of a department-wide retreat in a university department of psychiatry intended to (1) foster networking and communication among faculty who often work in "silos" and (2) invite the faculty to provide "internal consultations" regarding aspirational strategic goals and recommendations for short-term actionable tactics to address these goals. The retreat featured an evening networking and socializing poster session followed by a day-long event consisting of small group and large group interactive sessions. Participants were 120 faculty members including 44 new and younger faculty members who prepared and presented posters about themselves and their work. A variety of aspirational goals and specific recommendations for follow-up emerged from small groups were discussed in plenary sessions and were subsequently summarized and distributed to the faculty to be addressed by ongoing workgroups. Immediate informal feedback suggests that conducting and acting on recommendations ensuing from academic department retreats can foster at least a short-term sense of shared community and purpose, network faculty, identify commonly held values and aspirational goals, and potentially stimulate formation of innovative affinity groups and collaborations. Longer-term workgroup efforts and outcome assessments are required to assess the enduring results and value of such undertakings.

Effect of acid treated carbon nanotubes on mechanical, rheological and thermal properties of polystyrene nanocomposites

KAUST Repository

Amr, Issam Thaher

2011-09-01

In this work, multiwall carbon nanotubes (CNT) were functionalized by acid treatment and characterized using Fourier Transform Infrared Spectroscopy (FTIR) and thermogravimetric analysis (TGA). Polystyrene/CNT composites of both the untreated and acid treated carbon nanotubes were prepared by thermal bulk polymerization without any initiator at different loadings of CNT. The tensile tests showed that the addition of 0.5 wt.% of acid treated CNT results in 22% increase in Young\\'s modulus. The DSC measurements showed a decrease in glass transition temperature (Tg) of PS in the composites. The rheological studies at 190 °C showed that the addition of untreated CNT increases the viscoelastic behavior of the PS matrix, while the acid treated CNT acts as plasticizer. Thermogravimetric analysis indicated that the incorporation of CNT into PS enhanced the thermal properties of the matrix polymer. © 2011 Elsevier Ltd. All rights reserved.

Adsorption of benzene and toluene from aqueous solutions onto activated carbon and its acid and heat treated forms: influence of surface chemistry on adsorption.

Science.gov (United States)

Wibowo, N; Setyadhi, L; Wibowo, D; Setiawan, J; Ismadji, S

2007-07-19

The influence of surface chemistry and solution pH on the adsorption of benzene and toluene on activated carbon and its acid and heat treated forms were studied. A commercial coal-based activated carbon F-400 was chosen as carbon parent. The carbon samples were obtained by modification of F-400 by means of chemical treatment with HNO3 and thermal treatment under nitrogen flow. The treatment with nitric acid caused the introduction of a significant number of oxygenated acidic surface groups onto the carbon surface, while the heat treatment increases the basicity of carbon. The pore characteristics were not significantly changed after these modifications. The dispersive interactions are the most important factor in this adsorption process. Activated carbon with low oxygenated acidic surface groups (F-400Tox) has the best adsorption capacity.

Sorption of perfluorooctanoic acid, perfluorooctane sulfonate and perfluoroheptanoic acid on granular activated carbon.

Science.gov (United States)

Zhang, Di; Luo, Qi; Gao, Bin; Chiang, Sheau-Yun Dora; Woodward, David; Huang, Qingguo

2016-02-01

The sorption of perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and perfluoroheptanoic acid (PFHpA) on granular activated carbon (GAC) was characterized and compared to explore the underlying mechanisms. Sorption of the three perfluoroalkyl acids (PFAAs) on GAC appeared to be a rapid intra-particle diffusion process, which were well represented by the pseudo-second-order rate model with the sorption rate following the order PFOS > PFOA > PFHpA. Sorption isotherm data were well fitted by the Freundlich model with the sorption capacity (Kf) of PFOS, PFOA and PFHpA being 4.45, 2.42 and 1.66 respectively. This suggests that the hydrophilic head group on PFAAs, i.e. sulfonate vs carboxylic, has a strong influence on their sorption. Comparison between PFOA and PFHpA revealed that hydrophobicity could also play a role in the sorption of PFAAs on GAC when the fluorocarbon chain length is different. Analyses using Attenuated Total Reflection (ATR)-Fourier Transform Infrared (FTIR) spectroscopy suggested possible formation of a negative charge-assisted H-bond between PFAAs and the functionalities on GAC surfaces, including non-aromatic ketones, sulfides, and halogenated hydrocarbons. Copyright © 2015 Elsevier Ltd. All rights reserved.

Nano carbon supported platinum catalyst interaction behavior with perfluorosulfonic acid ionomer and their interface structures

DEFF Research Database (Denmark)

Andersen, Shuang Ma

2016-01-01

behavior of Nafion ionomer on platinized carbon nano fibers (CNFs), carbon nano tubes (CNTs) and amorphous carbon (Vulcan). The interaction is affected by the catalyst surface oxygen groups as well as porosity. Comparisons between the carbon supports and platinized equivalents are carried out. It reveals......The interaction between perfluorosulfonic acid ionomer and supported platinum catalyst is essential. It directly influences platinum accessibility, stability of carbon support and platinum, proton conductivity and electron conductivity in an electrode. In this study, we compare the adsorption...... that the platinization step modifies the surface nature of the carbon supports in terms of specific surface area, crystallinity and especially porosity; therefore, ionomer adsorption over carbon is not always representative for the ionomer adsorption over carbon supported catalyst, though indicative. Moreover...

Application of carbon and hydrogen stable isotope analyses to detect exogenous citric acid in Japanese apricot liqueur.

Science.gov (United States)

Akamatsu, Fumikazu; Oe, Takaaki; Hashiguchi, Tomokazu; Hisatsune, Yuri; Kawao, Takafumi; Fujii, Tsutomu

2017-08-01

Japanese apricot liqueur manufacturers are required to control the quality and authenticity of their liqueur products. Citric acid made from corn is the main acidulant used in commercial liqueurs. In this study, we conducted spiking experiments and carbon and hydrogen stable isotope analyses to detect exogenous citric acid used as an acidulant in Japanese apricot liqueurs. Our results showed that the δ 13 C values detected exogenous citric acid originating from C 4 plants but not from C 3 plants. The δ 2 H values of citric acid decreased as the amount of citric acid added increased, whether the citric acid originated from C 3 or C 4 plants. Commercial liqueurs with declared added acidulant provided higher δ 13 C values and lower δ 2 H values than did authentic liqueurs and commercial liqueurs with no declared added acidulant. Carbon and hydrogen stable isotope analyses are suitable as routine methods for detecting exogenous citric acid in Japanese apricot liqueur. Copyright © 2017 Elsevier Ltd. All rights reserved.

Glacier retreat and associated sediment dynamics in proglacial areas: a case study from the Silvretta Alps, Austria

Science.gov (United States)

Felbauer, Lucia; Pöppl, Ronald

2016-04-01

Global warming results in an ongoing retreat of glaciers in the Alps, leaving behind large amounts of easily erodible sediments. In addition, the debuttressing of rock-walls and the decay of permafrost in the high mountain regions facilitates mass movements of potential disastrous consequences, such as rock falls, landslides and debris flows. Therefore, it is highly important to quantify the amount of sediments that are supplied from the different compartments and to investigate how glacial retreat influences sediment dynamics in proglacial areas. In the presented work glacier retreat and associated sediment dynamics were investigated in the Kromer valley (Silvretta Alps, Austria) by analyzing remote sensing data. Glacial retreat from the period of 1950 to 2012 was documented by interpreting aerial photographs. By digitizing the different stages of the glaciers for six time frames, changes in glacier area and length were mapped and quantified. In order to identify, characterize and quantify sediment dynamics in the proglacial areas a high resolution DEM of difference (DoD) between 2007 and 2012 was created and analyzed, further differentiating between different zones (e.g. valley bottom, hillslope) and types of geomorphic processes (e.g. fluvial, gravitational). First results will be presented at the EGU General Assembly 2016.

Formic Acid Manufacture: Carbon Dioxide Utilization Alternatives

Directory of Open Access Journals (Sweden)

Marta Rumayor

2018-06-01

Full Text Available Carbon dioxide (CO2 utilization alternatives for manufacturing formic acid (FA such as electrochemical reduction (ER or homogeneous catalysis of CO2 and H2 could be efficient options for developing more environmentally-friendly production alternatives to FA fossil-dependant production. However, these alternatives are currently found at different technological readiness levels (TRLs, and some remaining technical challenges need to be overcome to achieve at least carbon-even FA compared to the commercial process, especially ER of CO2, which is still farther from its industrial application. The main technical limitations inherited by FA production by ER are the low FA concentration achieved and the high overpotentials required, which involve high consumptions of energy (ER cell and steam (distillation. In this study, a comparison in terms of carbon footprints (CF using the Life Cycle Assessment (LCA tool was done to evaluate the potential technological challenges assuring the environmental competitiveness of the FA production by ER of CO2. The CF of the FA conventional production were used as a benchmark, as well as the CF of a simulated plant based on homogeneous catalysts of CO2 and H2 (found closer to be commercial. Renewable energy utilization as PV solar for the reaction is essential to achieve a carbon-even product; however, the CF benefits are still negligible due to the enormous contribution of the steam produced by natural gas (purification stage. Some ER reactor configurations, plus a recirculation mode, could achieve an even CF versus commercial process. It was demonstrated that the ER alternatives could lead to lower natural resources consumption (mainly, natural gas and heavy fuel oil compared to the commercial process, which is a noticeable advantage in environmental sustainability terms.

Radioiodine uptake following iodine-131 therapy for Graves' disease: an early indicator of need for retreatment

International Nuclear Information System (INIS)

Carpentier, W.R.; Gilliland, P.F.; Piziak, V.K.; Petty, F.C.; McConnell, B.G.; Verdonk, C.A.; Ibarra, J.D.; Thompson, J.Q.

1989-01-01

Forty-five patients with Graves' disease were studied prospectively to determine if 24-hour I-131 uptake measurements alone or in combination with serum thyroid hormone levels at six weeks would determine the necessity for retreatment of the thyrotoxicosis. All patients with an I-131 uptake greater than 30% at six weeks required retreatment. No patient with an I-131 uptake of less than 15% required retreatment. Patients with uptakes between 15% and 30% were variable. An elevated free thyroxin index at 6 weeks is not helpful to determine which patients will remain thyrotoxic. Patients with a free thyroxin index within the normal range at six weeks can be predicted to be euthyroid by 12 weeks if their 24-hour I-131 uptake is between 15% and 30% and to be hypothyroid if their 24-hour I-131 uptake is below 15%. There was no difference between patient groups treated initially with antithyroid medication and those who were not

Incidence of apical crack initiation and propagation during the removal of root canal filling material with ProTaper and Mtwo rotary nickel-titanium retreatment instruments and hand files.

Science.gov (United States)

Topçuoğlu, Hüseyin Sinan; Düzgün, Salih; Kesim, Bertan; Tuncay, Oznur

2014-07-01

The aim of this study was to determine the incidence of crack initiation and propagation in apical root dentin after retreatment procedures performed by using 2 rotary retreatment systems and hand files with additional instrumentation. Eighty extracted mandibular premolars with single canals were selected. One millimeter from the apex of each tooth was ground perpendicular to the long axis of the tooth, and the apical surface was polished. Twenty teeth served as the control group, and no preparation was performed. The remaining 60 teeth were prepared to size 35 with rotary files and filled with gutta-percha and AH Plus sealer. Specimens were then divided into 3 groups (n = 20), and retreatment procedures were performed with the following devices and techniques: ProTaper Universal retreatment files, Mtwo retreatment files, and hand files. After retreatment, the additional instrumentation was performed by using size 40 ProTaper, Mtwo, and hand files. Digital images of the apical root surface were recorded before preparation, after instrumentation, after filling, after retreatment, and after additional instrumentation. The images were then inspected for the presence of any new apical cracks and propagation. Data were analyzed with the logistic regression and Fisher exact tests. All experimental groups caused crack initiation and propagation after use of retreatment instruments. The ProTaper and Mtwo retreatment groups caused greater crack initiation and propagation than the hand instrument group (P ProTaper and Mtwo instruments after the use of retreatment instruments caused crack initiation and propagation, whereas hand files caused neither crack initiation nor propagation (P < .05). This study showed that retreatment procedures and additional instrumentation after the use of retreatment files may cause crack initiation and propagation in apical dentin. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

A Functional Tricarboxylic Acid Cycle Operates during Growth of Bordetella pertussis on Amino Acid Mixtures as Sole Carbon Substrates.

Directory of Open Access Journals (Sweden)

Marie Izac

Full Text Available It has been claimed that citrate synthase, aconitase and isocitrate dehydrogenase activities are non-functional in Bordetella pertussis and that this might explain why this bacterium's growth is sometimes associated with accumulation of polyhydroxybutyrate (PHB and/or free fatty acids. However, the sequenced genome includes the entire citric acid pathway genes. Furthermore, these genes were expressed and the corresponding enzyme activities detected at high levels for the pathway when grown on a defined medium imitating the amino acid content of complex media often used for growth of this pathogenic microorganism. In addition, no significant PHB or fatty acids could be detected. Analysis of the carbon balance and stoichiometric flux analysis based on specific rates of amino acid consumption, and estimated biomass requirements coherent with the observed growth rate, clearly indicate that a fully functional tricarboxylic acid cycle operates in contrast to previous reports.

[Effects of simulated acid rain on decomposition of soil organic carbon and crop straw].

Science.gov (United States)

Zhu, Xue-Zhu; Huang, Yao; Yang, Xin-Zhong

2009-02-01

To evaluate the effects of acid rain on the organic carbon decomposition in different acidity soils, a 40-day incubation test was conducted with the paddy soils of pH 5.48, 6.70 and 8.18. The soils were amended with 0 and 15 g x kg(-1) of rice straw, adjusted to the moisture content of 400 g x kg(-1) air-dried soil by using simulated rain of pH 6.0, 4.5, and 3.0, and incubated at 20 degrees C. The results showed that straw, acid rain, and soil co-affected the CO2 emission from soil system. The amendment of straw increased the soil CO2 emission rate significantly. Acid rain had no significant effects on soil organic carbon decomposition, but significantly affected the straw decomposition in soil. When treated with pH 3.0 acid rain, the amount of decomposed straw over 40-day incubation in acid (pH 5.48) and alkaline (pH 8.18) soils was 8% higher, while that in neutral soil (pH 6.70) was 15% lower, compared to the treatment of pH 6.0 rain. In the treatment of pH 3.0 acid rain, the decomposition rate of soil organic C in acid (pH 5.48) soil was 43% and 50% (P pH 6.70) and alkaline (pH 8.18) soils, while the decomposition rate of straw in neutral soil was 17% and 16% (P < 0.05) lower than that in acid and alkaline soils, respectively.

Carbon catalysts for electrochemical hydrogen peroxide production in acidic media

DEFF Research Database (Denmark)

Čolić, Viktor; Yang, Sungeun; Révay, Zsolt

2018-01-01

Hydrogen peroxide is a commodity chemical, as it is an environmentally friendly oxidant. The electrochemical production of H2O2 from oxygen and water by the reduction of oxygen is of great interest, as it would allow the decentralized, on-site, production of pure H2O2. The ability to run...... the reaction in an acidic electrolyte with high performance is particularly important, as it would allow the use of polymer solid electrolytes and the production of pH-neutral hydrogen peroxide. Carbon catalysts, which are cheap, abundant, durable and can be highly selective show promise as potential catalysts...... for such systems. In this work, we examine the electrocatalytic performance and properties of seven commercially available carbon materials for H2O2 production by oxygen electroreduction. We show that the faradaic efficiencies for the reaction lie in a wide range of 18-82% for different carbon catalysts. In order...

Synthesis of {delta}-aminolevulic acid. Application to the introduction of carbon-14 and of tritium; Syntheses de l'acide {delta} aminolevulique. Application a l'introduction de carbone 14 et de tritium

Energy Technology Data Exchange (ETDEWEB)

Loheac, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1966-06-01

Several new syntheses of {delta} aminolevulic acid ({delta} A.L.A.) have been studied. {sup 14}C-4 {delta} - aminolevulic acid has been obtained from {sup 14}C allylacetic carboxylic acid with a yield of 30 per cent with respect to barium carbonate and with a specific activity of 32 mCi/mM. The {sup 14}C-1 or {sup 14}C-2 {delta}-A.L.A. has been prepared from the {sup 14}C-1 or {sup 14}C-2 acetate with a yield of 55 per cent with respect to the acetate. Finally the tritiated {delta}-A.L.A. has been obtained for the first time by tritiation of ethyl phthalimidodehydrolevulate. (author) [French] Plusieurs syntheses nouvelles de l'acide {delta}-aminolevulique ont ete etudiees. L'acide {delta}-aminolevulique {sup 14}C-4 a ete obtenu a partir d'acide allylacetique carboxylique {sup 14}C, avec un rendement global de 30 pour cent par rapport au carbonate de baryum a une activite specifique de 32 mCi/M. Le {delta}-A.A.L. {sup 14}C-1 ou {sup 14}C-2 a ete obtenu a partir d'acetate {sup 14}C-1 ou {sup 14}C-2 avec un rendement de 55 pour cent par rapport a l'acetate. Enfin le {delta}-A.A.L. tritie a ete obtenu pour la premiere fois par tritiation du phtalimidodehydrolevulate d'ethyle. (auteur)

In vitro evaluation of the effectiveness of ProTaper universal rotary retreatment system for gutta-percha removal with or without a solvent.

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Takahashi, Cristiane Midori; Cunha, Rodrigo Sanches; de Martin, Alexandre Sigrist; Fontana, Carlos Eduardo; Silveira, Cláudia Fernandes M; da Silveira Bueno, Carlos Eduardo

2009-11-01

Effective removal of gutta-percha in endodontic retreatment is a significant factor to ensure a favorable outcome from failed procedures. The purpose of this study was to evaluate the efficacy of a nickel-titanium rotary instrument system with or without a solvent versus stainless steel hand files for gutta-percha removal. Forty extracted human maxillary anterior teeth were prepared and filled. They were divided into 4 groups: Gates-Glidden and K-files, Gates-Glidden and K-files with chloroform, ProTaper Universal rotary retreatment system, and ProTaper Universal rotary retreatment system with chloroform. The operating time was recorded. The teeth were longitudinally sectioned and photographed. The images were analyzed and the filling remnants were quantified by using the IMAGE TOOL software. With Kruskall-Wallis test, statistical analysis showed that there was no significant difference between the techniques in regard to the amount of the endodontic filling remnants (P ProTaper Universal rotary retreatment system was faster than the hand files (P ProTaper Universal rotary retreatment system without chloroform was faster.

Efficacy of ProTaper Retreatment System in Root Canals Obturated with Gutta-Percha Using Two Different Sealers and GuttaFlow

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Siotia, Jaya; Acharya, Shashi Rashmi; Gupta, Sunil Kumar

2011-01-01

Objective. To compare the efficacy of ProTaper retreatment files in removing three different obturating materials. Study Design. Forty-five human, single-rooted premolars were divided into three experimental groups. Group 1 was obturated with gutta-percha and AH Plus sealer, Group 2 was obturated with gutta-percha and zinc oxide eugenol sealer, and Group 3 was obturated with GuttaFlow. Retreatment was done using the ProTaper universal rotary retreatment files. Root halves were visualized using magnifying loops at 3X magnification and optical stereomicroscope at 10X magnification. Images were analyzed using AutoCAD 2004 software to calculate area of the remaining debris in the canal. For statistical analysis were used variance test and ANOVA. Results. Total debris/canal area ratio between the three groups showed a statistically significant difference (P < 0.001). Conclusion. ProTaper retreatment system did not produce completely clean canals in any of the groups. However, it had the best efficacy towards removing silicon based obturating material GuttaFlow. PMID:22114598

Biological response to purification and acid functionalization of carbon nanotubes

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Figarol, Agathe; Pourchez, Jérémie; Boudard, Delphine; Forest, Valérie; Tulliani, Jean-Marc; Lecompte, Jean-Pierre; Cottier, Michèle; Bernache-Assollant, Didier; Grosseau, Philippe

2014-07-01

Acid functionalization has been considered as an easy way to enhance the dispersion and biodegradation of carbon nanotubes (CNT). However, inconsistencies between toxicity studies of acid functionalized CNT remain unexplained. This could be due to a joint effect of the main physicochemical modifications resulting from an acid functionalization: addition of surface acid groups and purification from catalytic metallic impurities. In this study, the impact on CNT biotoxicity of these two physiochemical features was assessed separately. The in vitro biological response of RAW 264.7 macrophages was evaluated after exposure to 15-240 µg mL-1 of two types of multi-walled CNT. For each type of CNT (small: 20 nm diameter, and big: 90 nm diameter), three different surface chemical properties were studied (total of six CNT samples): pristine, acid functionalized and desorbed. Desorbed CNT were purified by the acid functionalization but presented a very low amount of surface acid groups due to a thermal treatment under vacuum. A Janus effect of acid functionalization with two opposite impacts is highlighted. The CNT purification decreased the overall toxicity, while the surface acid groups intensified it when present at a specific threshold. These acid groups especially amplified the pro-inflammatory response. The threshold mechanism which seemed to regulate the impact of acid groups should be further studied to determine its value and potential link to the other physicochemical state of the CNT. The results suggest that, for a safer-design approach, the benefit-risk balance of an acid functionalization has to be considered, depending on the CNT primary state of purification. Further research should be conducted in this direction.

Reductive dehalogenation of haloacetic acids by hemoglobin-loaded carbon nanotube electrode.

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Li, Yu-Ping; Cao, Hong-Bin; Zhang, Yi

2007-01-01

Hemoglobin (Hb) was immobilized on carbon nanotube (CNT) electrode to catalyze the dehalogenation of haloacetic acids (HAAs). FTIR and UV measurements were performed to investigate the activity-keep of Hb after immobilization on CNT. The electrocatalytic behaviors of the Hb-loaded electrode for the dehalogenation of HAAs were studied by cyclic voltammmetry and constant-potential electrolysis technique. An Hb-loaded packed-bed flow reactor was also constructed for bioelectrocatalytic dehalogenation of HAAs. The results showed that Hb retained its nature, the essential features of its native secondary structure, and its biocatalytic activity after immobilization on CNT. Chloroacetic acids and bromoacetic acids could be dehalogenated completely with Hb catalysis through a stepwise dehalogenation process at -0.400V (vs. saturated calomel electrode (SCE)) and -0.200V (vs. SCE), respectively. The removal of 10.5mM trichloroacetic acid and dichloroacetic acid is ca. 97% and 63%, respectively, with electrolysis for 300min at -0.400V (vs. SCE) using the Hb-loaded packed-bed flow reactor, and almost 100% of tribromoacetic acid and dibromoacetic acid was removed with electrolysis for 40min at -0.200V (vs. SCE). The average current efficiency of Hb-catalytic dehalogenation almost reaches 100%.

Esterification of fatty acids using sulfated zirconia and composites activated carbon/sulfated zirconia catalysts

International Nuclear Information System (INIS)

Brum, Sarah S.; Santos, Valeria C. dos; Destro, Priscila; Guerreiro, Mario Cesar

2011-01-01

In this work sulfated zirconia (SZr) and activated carbon/SZr composites produced by impregnation method with or without heating treatment step (CABC/SZr-I and CABC/SZr-I SC) and by the method of synthesis of SZr on the carbon (CABC/SZr-S) was used as catalysts in the esterification reactions of fatty acids. The SZr presented very active, conversions higher than 90% were obtained after 2 h of reaction. The activity of the composite CABC/SZr-I20%SC was up to 92%, however, this was directly related to time and temperature reactions. CABC/SZr-I and CABC/SZr-S were less active in esterification reactions, what could be attributed to its low acidity. (author)

Decision logic for retreatment of asymptomatic lung cancer recurrence based on positron emission tomography findings

International Nuclear Information System (INIS)

Frank, Albert; Lefkowitz, David; Jaeger, Stanley; Gobar, Lisa; Sunderland, John; Gupta, Naresh; Scott, Walter; Mailliard, James; Lynch, Henry; Bishop, John; Thorpe, Patricia; Dewan, Naresh

1995-01-01

Purpose: The purpose of the study was to determine if Positron emission tomography (PET) 2-[F-18] fluoro-2-deoxy-D-glucose (FDG) imaging could detect subclinical local lung cancer recurrence and whether retreatment of such recurrence was feasible and beneficial. Methods and Materials: Twenty patients with biopsy proven lung cancer were studied with Positron emission tomography for the purpose of detecting subclinical lung cancer recurrence over a period of 4.25 years. All patients were treated with external radiation as part or all of their therapy. Twenty patients had baseline PET and computed tomography (CT) studies for comparison with later studies. Surviving patients had a total of 40 sequential PET scans and 35 CT scans. The follow-up interval ranged from 5 to 40 months posttreatment. The differential uptake ratio (DUR) was determined for regions of interest of increased FDG uptake. Results: The median DUR value of the 20 baseline PET studies was 5.59. The DUR value of greater than 3 was empirically selected as being positive for tumor detection. On baseline studies, PET had a 100% correlation with the CT findings in regard to detection of the site of primary tumor involvement. Four of 20 patients showed areas of discordance in the mediastinal and hilar areas on initial PET and CT studies. Seven of 17 patients showed discordant posttreatment PET-CT findings. Two false positive PET studies were due to radiation pneumonitis and one to macrophage glycolysis in tumor necrosis. For detection of asymptomatic tumor recurrence, analysis of sequential PET and CT studies, biopsy results, and the patient's clinical course suggested that PET had a sensitivity of 100%, specificity of 89.3%, and accuracy of 92.5%. Computerized Tomography was found to have a sensitivity of 67%, specificity of 85%, and accuracy of 82% for detection of such early-stage recurrence. Five patients went on to have retreatment with external irradiation based upon the PET evidence. Four retreated

Influence of sodium carbonate on decomposition of formic acid by pulsed discharge plasma inside bubble in water

Science.gov (United States)

Iwabuchi, Masashi; Takahashi, Katsuyuki; Takaki, Koichi; Satta, Naoya

2016-07-01

The influence of sodium carbonate on the decomposition of formic acid by discharge inside bubbles in water was investigated experimentally. Oxygen or argon gases were injected into the water through a vertically positioned glass tube, in which the high-voltage wire electrode was placed to generate plasmas at low applied voltage. The concentration of formic acid was determined by ion chromatography. In the case of sodium carbonate additive, the pH increased owing to the decomposition of the formic acid. In the case of oxygen injection, the percentage of conversion of formic acid increased with increasing pH because the reaction rate of ozone with formic acid increased with increasing pH. In the case of argon injection, the percentage of conversion was not affected by the pH owing to the high rate loss of hydroxyl radicals.

Electrochemical Investigation of Carbon as Additive to the Negative Electrode of Lead-Acid Battery

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Fernandez Matthew M.

2015-01-01

Full Text Available The increasing demand of cycle life performance of Pb-acid batteries requires the improvement of the negative Pb electrode’s charge capacity. Electrochemical investigations were performed on Pb electrode and Pb+Carbon (Carbon black and Graphite electrodes to evaluate the ability of the additives to enhance the electrochemical faradaic reactions that occur during the cycle of Pb-acid battery negative electrode. The electrodes were characterized through Cyclic Voltammetry (CV, Potentiodynamic Polarization (PP, and Electrochemical Impedance Spectroscopy (EIS. CV revealed that the addition of carbon on the Pb electrode increased anodic and cathodicreactions by tenfold. The kinetics of PbSO4 passivation measured through PPrevealed that the addition of Carbon on the Pb electrode accelerated the oxide formation by tenfold magnitude. The Nyquist plot measured through EIS suggest that the electrochemical mechanism and reaction kinetics is under charge-transfer. From the equivalent circuit and physical model, Pb+CB1 electrode has the lowest EIS parameters while Pb+G has the highest which is attributed to faster faradaic reaction.The Nyquist plot of the passivated Pb+CB1 electrode showed double semicircular shape. The first layer represents to the bulk passive PbSO4 layer and the second layer represents the Carbon+PbSO4 layer. The enhancements upon addition of carbon on the Pb electrode were attributed to the additive’s electrical conductivity and total surface area. The electrochemical active sites for the PbSO4 to nucleate and spread increases upon addition of electrical conductive and high surface area carbon additives.

Endodontic retreatment: clinical comparison of reciprocating systems versus rotary system in disinfecting root canals.

Science.gov (United States)

Martinho, Frederico C; Freitas, Lilian F; Nascimento, Gustavo G; Fernandes, Aleteia M; Leite, Fabio R M; Gomes, Ana P M; Camões, Izabel C G

2015-07-01

This clinical study was conducted to compare the effectiveness of single-file reciprocating systems and rotary systems in removing endotoxins and cultivable bacteria in endodontic retreatment. Thirty endodontically treated teeth with post-treatment apical periodontitis were selected. The specimens were divided into three groups according to the system used: WaveOne (n = 10), Reciproc instrument (n = 10), and ProTaper Universal Retreatment system (n = 10). Samples were collected before and after chemomechanical preparation. The irrigation was performed by using 2.5% sodium hypochlorite. A chromogenic limulus amebocyte lysate assay test was used to quantify endotoxins. Culture techniques were used to determine bacterial colony-forming unit counts. At baseline, endotoxins and cultivable bacteria were recovered from 100% of the root canal samples in a median value of 5.84 EU/mL and 4.98 × 10(3) CFU/mL, respectively. After CMP, no differences were found in the median percentage values of endotoxin reduction achieved with reciprocating systems-WaveOne [94.11%] and Reciproc [93.29%] and with rotary systems-ProTaper [94.98%] (P > 0.05). Both single-file reciprocating systems [WaveOne (98.27%) and Reciproc (99.54%)] and rotary system [ProTaper (98.73%)] were effective in reducing bacterial load (P > 0.05). Moreover, no differences were found among the systems tested. The Reciproc and WaveOne reciprocating systems were as effective as the ProTaper system for removal of endotoxins and bacteria in endodontic retreatment. All systems tested were effective to remove cultivable bacteria and endotoxin in endodontic retreatment. As no differences among systems were observed, it is possible to suggest that clinicians should choose the preferred technique to perform endodontic.

Enhanced performance of starter lighting ignition type lead-acid batteries with carbon nanotubes as an additive to the active mass

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Marom, Rotem; Ziv, Baruch; Banerjee, Anjan; Cahana, Beni; Luski, Shalom; Aurbach, Doron

2015-11-01

Addition of various carbon materials into lead-acid battery electrodes was studied and examined in order to enhance the power density, improve cycle life and stability of both negative and positive electrodes in lead acid batteries. High electrical-conductivity, high-aspect ratio, good mechanical properties and chemical stability of multi-wall carbon nanotubes (MWCNT, unmodified and mofified with carboxylic groups) position them as viable additives to enhance the electrodes' electrical conductivity, to mitigate the well-known sulfation failure mechanism and improve the physical integration of the electrodes. In this study, we investigated the incorporation-effect of carbon nanotubes (CNT) to the positive and the negative active materials in lead-acid battery prototypes in a configuration of flooded cells, as well as gelled cells. The cells were tested at 25% and 30% depth-of-discharge (DOD). The positive effect of the carbon nanotubes (CNT) utilization as additives to both positive and negative electrodes of lead-acid batteries was clearly demonstrated and is explained herein based on microscopic studies.

Bathymetry and retreat of Southeast Greenland glaciers from Operation IceBridge and Ocean Melting Greenland data

Science.gov (United States)

Millan, R.; Rignot, E. J.; Morlighem, M.; Bjork, A. A.; Mouginot, J.; Wood, M.

2017-12-01

Southeast Greenland has been one of the largest contributors to ice mass loss in Greenland in part because of significant changes in glacier dynamics. The leading hypothesis for the changes in glacier dynamics is that enhanced thermal forcing from the ocean has dislodged a number of glaciers from their anchoring positions and some of them retreated rapidly along a reverse bed. The glaciers response has been observed to vary significantly from one fjord to the next, but until now there was not enough data to understand or interpret these changes. In particular, there was no data on glacier bed topography and seafloor bathymetry in the fjords. Here we present the results of new fjord mapping by the NASA Ocean Melting Greenland mission combined with a recent high-resolution airborne gravity survey by NASA Operation IceBridge. We combine these data with a reconstruction of the bed using a mass conservation approach upstream extending into the glacial fjords for the first time. In the fjord and along the ice-ocean transition, we employ a 3D inversion of gravity data to infer the bed elevation along a set of 9 survey boxes spanning south of Helheim Glacier to the southern tip of Southeast Greenland. We combine the results with an analysis of the glacier front history since the 1930's and Conductivity Temperature Depth data obtained in the fjord by OMG in 2016. The data reveals bed elevations several 100-m deeper than previously thought, for almost all the glaciers, up to 500 m for some of them. For many glaciers, the bed profiles help to completely understand the history of retreat of the glaciers. For instance, glaciers stranded on sills have been stable; glaciers on a reverse slope have retreated rapidly; and glaciers with a normal slope have retreated slowly. The mapping also helps document the extent of the marine portion of the glacier basins. In many of the fjords, we document the presence of warm, salty Atlantic Water which fuels large melt rates. We employ

FATTY ACID STABLE ISOTOPE INDICATORS OF MICROBIAL CARBON SOURCE IN TROPICAL SOILS

Science.gov (United States)

The soil microbial community plays an important role in tropical ecosystem functioning because of its importance in the soil organic matter (SOM) cycle. We have measured the stable carbon isotopic ratio (delta13C) of individual phospholipid fatty acids (PLFAs) in a variety of tr...

Biotechnology humic acids-based electrospun carbon nanofibers as cost-efficient electrodes for lithium-ion batteries

International Nuclear Information System (INIS)

Zhao, Pin-Yi; Guo, Yan; Yu, Bao-Jun; Zhang, Jie; Wang, Cheng-Yang

2016-01-01

Bio-based, cost-effective carbon nanofibers are fabricated from polyacrylonitrile (PAN) – refined biotechnology humic acids (RB) via simple eletrospinning after stabilization and carbonization. The influence of PAN/RB mass ratios and heat-treatment temperatures (HTTs) on structure and morphology is systematically studied. Excitingly, a first discharge/charge capacity of 937.9/613.4 mAh g −1 (coulombic efficiency of 65.4%) is achieved at 20 mA g −1 for PB7/3-800 in lithium-ion batteries (LIBs). Meanwhile, a charge capacity of 348.2 mAh g −1 (about 89% retention ratio) remains even after 100 cycles at 0.1 A g −1 . It is demonstrated that biomass humic acids can be applied as a promising precursor to fabricate high performance, low-cost, as well as “green” carbon electrode material for LIBs.

Physicochemical pretreatments and hydrolysis of furfural residues via carbon-based sulfonated solid acid.

Science.gov (United States)

Ma, Bao Jun; Sun, Yuan; Lin, Ke Ying; Li, Bing; Liu, Wan Yi

2014-03-01

Potential commercial physicochemical pretreatment methods, NaOH/microwave and NaOH/ultrasound were developed, and the carbon-based sulfonated solid acid catalysts were prepared for furfural residues conversion into reducing sugars. After the two optimum pretreatments, both the content of cellulose increased (74.03%, 72.28%, respectively) and the content of hemicellulose (94.11%, 94.17% of removal rate, respectively) and lignin (91.75%, 92.09% of removal rate, respectively) decreased in furfural residues. The reducing sugar yields of furfural residues with the two physicochemical pretreatments on coal tar-based solid acid reached 33.94% and 33.13%, respectively, higher than that pretreated via NaOH alone (27%) and comparable to that pretreated via NaOH/H2O2 (35.67%). The XRD patterns, IR spectra and SEM images show microwave and ultrasound improve the pretreatment effect. The results demonstrate the carbon-based sulfonated solid acids and the physicochemical pretreatments are green, effective, low-cost for furfural residues conversion. Copyright © 2014 Elsevier Ltd. All rights reserved.

Panretinal photocoagulation versus intravitreal injection retreatment pain in high-risk proliferative diabetic retinopathy

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Célia Regina Farias de Araújo Lucena

2013-02-01

Full Text Available PURPOSE: To compare pain related to intravitreal injection and panretinal photocoagulation in the management of patients with high-risk proliferative diabetic retinopathy. METHODS: Prospective study including patients with high-risk proliferative diabetic retinopathy and no prior laser treatment randomly assigned to receive panretinal photocoagulation (PRP group or panretinal photocoagulation plus intravitreal ranibizumab (PRPplus group. In all patients, panretinal photocoagulation was administered in two sessions (weeks 0 and 2, and intravitreal ranibizumab was administered at the end of the first laser session in the PRPplus group. Retreatment was performed at weeks 16 and 32 if active new vessels were detected at fluorescein angiography. Patients in the PRPplus group received intravitreal ranibizumab and patients in the PRP group received 500-µm additional spots per quadrant of active new vessels. After the end of retreatment, a 100-degree Visual Analog Scale was used for pain score estimation. The patient was asked about the intensity of pain during the whole procedure (retinal photocoagulation session or intravitreal ranibizumab injection. Statistics for pain score comparison were performed using a non-parametric test (Wilcoxon rank sums. RESULTS: Seventeen patients from PRPplus and 14 from PRP group were evaluated for pain scores. There were no significant differences between both groups regarding gender, glycosylated hemoglobin and disease duration. Mean intravitreal injection pain (±SEM was 4.7 ± 2.1 and was significantly lower (p<0.0001 than mean panretinal photocoagulation pain (60.8 ± 7.8. Twelve out of 17 patients from the PRPplus group referred intensity pain score of zero, while the minimal score found in PRP group was found in one patient with 10.5. CONCLUSION: In patients with high-risk proliferative diabetic retinopathy who needed retreatment for persistent new vessels, there was more comfort for the patient when retreatment

Root Canal Retreatment menggunakan Kombinasi Kalsium Hidroksida dan Chlorhexidine sebagai Medikamen Intra Kanal Insisivus Sentral Kiri Maksila

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Andina Novita Sari

2014-12-01

retreatment dengan cleaning dan shaping ulang yang baik dengan menggunakan medikasi intrakanal berupa kombinasi kalsium hidroksida dan chlorhexidine 2% diharapkan mempunyai efek antimikroba yang sinergis untuk mencapai kesuksesan root canal retreatment.   Root Canal Retreatment Using Calcium Hydroxide as Intra Canal Medicament On The Maxillary Left Incisor. Enterococcus faecalis bacteria is most abundant in the root canal infection treated endodontically. Chlorhexidine has a broad antibacterial spectrum and has been used as an endodontic irrigant and intracanal medication. Chlorhexidine has a bactericidal and fungicidal effect as chlorhexidine absorbed into the bacterial cell surface and cause damage to the integrity of the cell membrane. Calcium hydroxide is a biocompatible, antimicrobial agents with high pH effects and stimulates hard tissue formation. A mixture of calcium hydroxide and chlorhexidine is used to control bacteria Enterococcus faecalis alternative. The purpose of this case report is to report on the success of root canal treatment in the left maxillary central incisor with acute periapical periodontitis using a combination of calcium hydroxide and chlorhexidine as intracanal A 24 years old female patient presents with left upper central incisor tooth ache since 4 years ago. The tooth was hurt to percussion, but normal to pulpation as well as the mobility. The tooth has a history of previous trauma and broken 6 years ago and has performed endodontic treatment. Radiographic examination showed obturation teeth 21 are not hermetic with periapical radiolucency in diffuse boundaries, widening of the periodontal ligament and the dissolution of the lamina dura. Root canal re-treatment using a combination of calcium hydroxide and chlorhexidine as intracanal medicaments were performed. In conclussion, the root canal cleaning and shaping retreatment can be performed using a combination of calcium hydroxide and chlorhexidine as intracanal

The Multitrophic Effects of Climate Change and Glacier Retreat in Mountain Rivers.

Science.gov (United States)

Fell, Sarah C; Carrivick, Jonathan L; Brown, Lee E

2017-10-01

Climate change is driving the thinning and retreat of many glaciers globally. Reductions of ice-melt inputs to mountain rivers are changing their physicochemical characteristics and, in turn, aquatic communities. Glacier-fed rivers can serve as model systems for investigations of climate-change effects on ecosystems because of their strong atmospheric-cryospheric links, high biodiversity of multiple taxonomic groups, and significant conservation interest concerning endemic species. From a synthesis of existing knowledge, we develop a new conceptual understanding of how reducing glacier cover affects organisms spanning multiple trophic groups. Although the response of macroinvertebrates to glacier retreat has been well described, we show that there remains a relative paucity of information for biofilm, microinvertebrate, and vertebrate taxa. Enhanced understanding of whole river food webs will improve the prediction of river-ecosystem responses to deglaciation while offering the potential to identify and protect a wider range of sensitive and threatened species.

The erosion of carbonate stone by acid rain: Laboratory and field investigations

International Nuclear Information System (INIS)

Baedecker, P.A.; Reddy, M.M.

1993-01-01

This paper describes a laboratory experiment on the effects of acidic deposition on carbonate stone erosion. It can serve as the basis for an undergraduate (or pre college) experiment in environmental chemistry. Recent field investigations are described that provide measurements of carbonate stone dissolution and mechanical erosion under weathering conditions that are prevalent in the eastern US. The purpose of the laboratory work is to answer questions concerning the effects of hydrogen ion deposition on stone erosion processes that were difficult to resolve on the basis of field experiments alone

CARBON CRYOGEL MICROSPHERE FOR ETHYL LEVULINATE PRODUCTION: EFFECT OF CARBONIZATION TEMPERATURE AND TIME

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MUZAKKIR M. ZAINOL

2016-07-01

Full Text Available The side products of biomass and bio-fuel industry have shown potential in producing carbon catalyst. The carbon cryogel was synthesized from ligninfurfural mixture based on the following details: 1.0 of lignin to furfural (L/F ratio, 1.0 of lignin to water (L/W ratio, and 8M of acid concentration. The lignin-furfural sol-gel mixture, initially prepared via polycondensation reaction at 90 °C for 30 min, was followed by freeze drying and carbonization process. Effects of carbonization temperature and time were investigated on the total acidity and surface area of the carbon cryogel. Furthermore, the effects of these parameters were studied on the ethyl levulinate yield through esterification reaction of levulinic acid in ethanol. The esterification reaction was conducted at reflux temperature, 10 h of reaction time, 19 molar ratio of ethanol to levulinic acid, and 15.0 wt.% carbon cryogel loading. Based on the carbonization temperature and time studies, the carbon cryogel carbonized at 500 °C and 4 h exhibited good performance as solid acid catalyst. Large total surface area and acidity significantly influenced the catalytic activity of carbon cryogel with 80.0 wt.% yield of ethyl levulinate. Thus, carbon cryogel is highly potential as acid catalyst for the esterification of levulinic acid with ethanol.

The retreat of the world's mountain glaciers during recent decades

International Nuclear Information System (INIS)

Francou, B.; Vincent, Ch.

2009-01-01

Glaciers have become essential tools for measuring changes in the global environment. Here, we analyze glacier evolution during the last few decades and we wonder whether the observed retreat remains in the range of glacier fluctuations since the mid-Holocene. The main fluctuations experienced by glaciers during the last millenniums, and particularly during the Little Ice Age (-1300 A.D. to ∼1860 A.D.), are presented succinctly. The recent 1960-2005 period, well documented both by ground and remote sensing observations, shows important disparities between different massifs concerning the timing and the magnitude of glacier fluctuations, which depend on regional climatic conditions. The links between glacier mass balance evolution and climate is clear when approached from an energy balance but the variables commonly considered are only temperature and precipitation. The strong correlation existing between these variables and the mass balance evolution makes it possible to simulate glaciers in the future in function of distinct climatic scenarios. Modeling glacier retreat for the 21. century is an important goal because it will allow the impacts on water resource and sea level to be assessed. (authors)

Galvanic corrosion between carbon steel 1018 and Alloy 600 in crevice with boric acid solution

International Nuclear Information System (INIS)

Kim, Dong Jin; Kim, Hong Pyo; Kim, Joung Soo; Machonald, Digby D.

2005-01-01

This work dealt with the evaluation of galvanic corrosion rate in a corrosion cell having annular gap of 0.5 mm between carbon steel 1018 and alloy 600 as a function of temperature and boron concentration. Temperature and boron concentration were ranged from 110 to 300 .deg. C and 2000∼10000 ppm, respectively. After the operating temperature of the corrosion cell where the electrolyte was injected was attained at setting temperature, galvanic coupling was made and at the same time galvanic current was measured. The galvanic corrosion rate decreased with time, which was described by corrosion product such as protective film as well as boric acid deposit formed on the carbon steel with time. From the galvanic current obtained as a function of temperature and boron concentration, it was found that the galvanic corrosion rate decreased with temperature while the corrosion rate increased with boron concentration. The experimental results obtained from galvanic corrosion measurement were explained by adhesive property of corrosion product such as protective film, boric acid deposit formed on the carbon steel wall and dehydration of boric acid to be slightly soluble boric acid phase. Moreover the galvanic corrosion rate calculated using initial galvanic coupling current instead of steady state coupling current was remarked, which could give us relatively closer galvanic corrosion rate to real pressurized water reactor

Bioreversible Derivatives of Phenol. 2. Reactivity of Carbonate Esters with Fatty Acid-like Structures Towards Hydrolysis in Aqueous Solutions

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Claus Larsen

2007-10-01

Full Text Available A series of model phenol carbonate ester prodrugs encompassing derivatives with fatty acid-like structures were synthesized and their stability as a function of pH (range 0.4 – 12.5 at 37°C in aqueous buffer solutions investigated. The hydrolysis rates in aqueous solutions differed widely, depending on the selected pro-moieties (alkyl and aryl substituents. The observed reactivity differences could be rationalized by the inductive and steric properties of the substituent groups when taking into account that the mechanism of hydrolysis may change when the type of pro-moiety is altered, e.g. n-alkyl vs. t-butyl. Hydrolysis of the phenolic carbonate ester 2-(phenoxycarbonyloxy-acetic acid was increased due to intramolecular catalysis, as compared to the derivatives synthesized from ω-hydroxy carboxylic acids with longer alkyl chains. The carbonate esters appear to be less reactive towards specific acid and base catalyzed hydrolysis than phenyl acetate. The results underline that it is unrealistic to expect that phenolic carbonate ester prodrugs can be utilized in ready to use aqueous formulations. The stability of the carbonate ester derivatives with fatty acid-like structures, expected to interact with the plasma protein human serum albumin, proved sufficient for further in vitro and in vivo evaluation of the potential of utilizing HSA binding in combination with the prodrug approach for optimization of drug pharmacokinetics.

Skin-deep diagnosis: affective bias and zebra retreat complicating the diagnosis of systemic sclerosis.

Science.gov (United States)

Miller, Chad S

2013-01-01

Nearly half of medical errors can be attributed to an error of clinical reasoning or decision making. It is estimated that the correct diagnosis is missed or delayed in between 5% and 14% of acute hospital admissions. Through understanding why and how physicians make these errors, it is hoped that strategies can be developed to decrease the number of these errors. In the present case, a patient presented with dyspnea, gastrointestinal symptoms and weight loss; the diagnosis was initially missed when the treating physicians took mental short cuts and used heuristics as in this case. Heuristics have an inherent bias that can lead to faulty reasoning or conclusions, especially in complex or difficult cases. Affective bias, which is the overinvolvement of emotion in clinical decision making, limited the available information for diagnosis because of the hesitancy to acquire a full history and perform a complete physical examination in this patient. Zebra retreat, another type of bias, is when a rare diagnosis figures prominently on the differential diagnosis but the physician retreats for various reasons. Zebra retreat also factored in the delayed diagnosis. Through the description of these clinical reasoning errors in an actual case, it is hoped that future errors can be prevented or inspiration for additional research in this area will develop.

Non-covalent conjugates of single-walled carbon nanotubes and folic acid for interaction with cells overexpressing folate receptors

DEFF Research Database (Denmark)

Castillo, John J.; Rindzevicius, Tomas; Novoa, Leidy V.

2013-01-01

We here present amethod to form a noncovalent conjugate of single-walled carbon nanotubes and folic acid aimed to interact with cells over-expressing folate receptors. The bonding was obtained without covalent chemical functionalization using a simple, rapid “one pot” synthesis method. The zeta...... a low toxicity of the conjugates in the THP-1 cells. The low toxicity and the cellular uptake of single-walled carbon nanotube–folic acid by cancer cells suggest their potential use in carbon nanotube-based drug delivery systems and in the diagnosis of cancer or tropical diseases such as leishmaniasis....

Further investigation on boric acid catalytic graphitization of polyacrylonitrile carbon fibers: Mechanism and mechanical properties

International Nuclear Information System (INIS)

Wen, Ya; Lu, Yonggen; Xiao, Hao; Qin, Xianying

2012-01-01

Highlights: ► The modulus of carbon fiber was improved by boric acid at the temperature range of 1500–2900 °C. ► 2300 °C is a key temperature degree from which the boron began to benefit fiber strength. ► The fiber strength was affected by the boron reaction and related to the boron states. -- Abstract: Catalytic graphitization of polyacrylonitrile based carbon fibers by boric acid doping was studied and the dependence of fiber tensile strength on the boron content and temperature was discussed. It was found that there existed a key temperature point for the boron to take effect. When the fibers were modified with 7.0 wt.% boric acid solution, with increasing temperature, the tensile strength was lower than that of the unmodified ones below 2300 °C, but a reverse thing happened above 2300 °C. Moreover, when being heated at 2500 °C, the modified fibers showed an increasing tensile modulus and strength with increasing boron content till maximums of 404 GPa and 2.46 GPa, 26% and 16% higher than those of unmodified ones. The mechanical properties of the fibers were affected by the interaction of carbon and boron, and also related with boron states. The decomposition of boron acid and its interaction with carbon brought defects on fiber surface, degrading the mechanical properties below 1300 °C. With further heat treatment, the boron diffused into the fibers and divided into two states: substitutional and interstitial. At a temperature over 2300 °C with an appreciate boron content, the substitutional would be formed predominantly, which removed the structural defects and relaxed the distortions, so as to benefit the mechanical properties.

Improved age constraints for the retreat of the Irish Sea Ice Stream

Science.gov (United States)

Smedley, Rachel; Chiverrell, Richard; Duller, Geoff; Scourse, James; Small, David; Fabel, Derek; Burke, Matthew; Clarke, Chris; McCarroll, Danny; McCarron, Stephen; O'Cofaigh, Colm; Roberts, David

2016-04-01

BRITICE-CHRONO is a large (> 45 researchers) consortium project working to provide an extensive geochronological dataset constraining the rate of retreat of a number of ice streams of the British-Irish Ice Sheet following the Last Glacial Maximum. When complete, the large empirical dataset produced by BRITICE-CHRONO will be integrated into model simulations to better understand the behaviour of the British-Irish Ice Sheet in response to past climate change, and provide an analogue for contemporary ice sheets. A major feature of the British-Irish Ice Sheet was the dynamic Irish Sea Ice Stream, which drained a large proportion of the ice sheet and extended to the proposed southern limit of glaciation upon the Isles of Scilly (Scourse, 1991). This study will focus on a large suite of terrestrial samples that were collected along a transect of the Irish Sea basin, covering the line of ice retreat from the Isles of Scilly (50°N) in the south, to the Isle of Man (54°N) in the north; a distance of 500 km. Ages are determined for both the eastern and western margins of the Irish Sea using single-grain luminescence dating (39 samples) and terrestrial cosmogenic nuclide dating (10 samples). A Bayesian sequence model is then used in combination with the prior information determined for deglaciation to integrate the geochronological datasets, and assess retreat rates for the Irish Sea Ice Stream. Scourse, J.D., 1991. Late Pleistocene stratigraphy and palaeobotany of the Isles of Scilly. Philosophical Transactions of the Royal Society of London B334, 405 - 448.

Modelling Waterfall Retreat in Heterogenous Bedrock

Science.gov (United States)

Attal, M.; Hodge, R. A.; Williams, R.; Baynes, E.

2016-12-01

Bedrock rivers are the mediators of environmental change through mountainous landscapes. In response to an increase in uplift rate for example, a "knickpoint" (often materialised as a waterfall) will propagate upstream, separating a domain downstream where the river and its adjacent hillslopes have steepened in response to the change from a "relict" domain upstream which is adjusted to the conditions before the change (Crosby and Whipple 2006). Many studies assume that knickpoint propagation rate scales with drainage area, based on the stream power theory. However, recent studies in a range of locations have found no obvious relationship between knickpoint retreat rate and drainage area, potentially resulting from the stream power law neglecting (i) the influence of sediment on the processes associated with waterfall migration and (ii) thresholds for bedrock detachment (Cook et al. 2013; Mackey et al. 2014; DiBiase et al. 2015; Baynes et al. 2015; Brocard et al. 2016). In this study, we develop a 1D model of waterfall retreat in horizontally bedded bedrock with varying joint spacing. In the model, knickpoint migration is based on two rules: a waterfall will start migrating once the threshold flow depth (a function of knickpoint height and joint spacing) has been exceeded (Lamb and Dietrich 2009), and the migration rate will then be a function of the water-depth-to-waterfall-height ratio, based on experimental results by Baynes (2015). Using a hydrograph based on a Poisson rectangular pulse rainfall simulator (Tucker and Bras 2001), we demonstrate the importance of structure in controlling the speed at which waterfalls migrate but also their number and the length over which they are distributed (Fig. 1). The model is applied to the Jökulsá á Fjöllum, NE Iceland, where rapid migration of waterfalls as a result of discrete events has been identified (Baynes et al. 2015), using new constraints on joint spacing derived from high resolution lidar survey of the gorge

ACL Research Retreat VI : An update on ACL injury risk and prevention

NARCIS (Netherlands)

R.J. Schmitz; M. Collins; D.A. Padua; Anne Benjaminse; A.M. Chaudhari; S.J. Schultz

2012-01-01

It has been well recognized that multiple factors, whether individually or in combination, contribute to noncontact anterior cruciate ligament (ACL) injury. The ongoing mission of the ACL Research Retreat is to bring clinicians and researchers together to present and discuss the most recent advances

Probabilistic estimation of dune retreat on the Gold Coast, Australia

Science.gov (United States)

Palmsten, Margaret L.; Splinter, Kristen D.; Plant, Nathaniel G.; Stockdon, Hilary F.

2014-01-01

Sand dunes are an important natural buffer between storm impacts and development backing the beach on the Gold Coast of Queensland, Australia. The ability to forecast dune erosion at a prediction horizon of days to a week would allow efficient and timely response to dune erosion in this highly populated area. Towards this goal, we modified an existing probabilistic dune erosion model for use on the Gold Coast. The original model was trained using observations of dune response from Hurricane Ivan on Santa Rosa Island, Florida, USA (Plant and Stockdon 2012. Probabilistic prediction of barrier-island response to hurricanes, Journal of Geophysical Research, 117(F3), F03015). The model relates dune position change to pre-storm dune elevations, dune widths, and beach widths, along with storm surge and run-up using a Bayesian network. The Bayesian approach captures the uncertainty of inputs and predictions through the conditional probabilities between variables. Three versions of the barrier island response Bayesian network were tested for use on the Gold Coast. One network has the same structure as the original and was trained with the Santa Rosa Island data. The second network has a modified design and was trained using only pre- and post-storm data from 1988-2009 for the Gold Coast. The third version of the network has the same design as the second version of the network and was trained with the combined data from the Gold Coast and Santa Rosa Island. The two networks modified for use on the Gold Coast hindcast dune retreat with equal accuracy. Both networks explained 60% of the observed dune retreat variance, which is comparable to the skill observed by Plant and Stockdon (2012) in the initial Bayesian network application at Santa Rosa Island. The new networks improved predictions relative to application of the original network on the Gold Coast. Dune width was the most important morphologic variable in hindcasting dune retreat, while hydrodynamic variables, surge and

Healing the heart: a randomized pilot study of a spiritual retreat for depression in acute coronary syndrome patients.

Science.gov (United States)

Warber, Sara L; Ingerman, Sandra; Moura, Vera L; Wunder, Jenna; Northrop, Alyssa; Gillespie, Brenda W; Durda, Kate; Smith, Katherine; Rhodes, Katherine S; Rubenfire, Melvyn

2011-01-01

Depression is associated with increased risk of cardiovascular morbidity and mortality in coronary heart disease. Numerous conventional and complementary therapies may address depression. Few involving spirituality have been tested. The aim of this study was to compare the effects of a nondenominational spiritual retreat, Medicine for the Earth (MFTE), on depression and other measures of well-being six- to 18-months post acute coronary syndrome (ACS). A randomized controlled pilot study of MFTE, Lifestyle Change Program (LCP), or usual cardiac care (control) was conducted in Southeastern Michigan. ACS patients were recruited via local and national advertising (n = 58 enrolled, 41 completed). The four-day MFTE intervention included guided imagery, meditation, drumming, journal writing, and nature-based activities. The four-day LCP included nutrition education, exercise, and stress management. Both retreat groups received follow-up phone coaching biweekly for three months. Validated self-report scales of depression, spiritual well-being, perceived stress, and hope were collected at baseline, immediately post-retreat, and at three and six months. Depression was not significantly different among groups (P = .21). However, the MFTE group had the highest depression scores at baseline and had significantly lower scores at all postintervention time points (P ≤ .002). Hope significantly improved among MFTE participants, an effect that persisted at three- and six-month follow-up (P = .014). Although several measures showed improvement in all groups by six months, the MFTE group had immediate improvement post-retreat, which was maintained. This pilot study shows that a nondenominational spiritual retreat, MFTE, can be used to increase hope while reducing depression in patients with ACS. Copyright © 2011 Elsevier Inc. All rights reserved.

Redox thermodynamic data of plutonium in acidic and carbonate media. Pu(V) stability

International Nuclear Information System (INIS)

Capdevila, H.

1992-01-01

Pu redox equilibria are studied in acidic and carbonate media in this thesis, to build a thermodynamic data bank consistent with the TDB (NEA-OECD) one and in connection with radioactive waste disposal programs. Literature is discussed and reinterpreted. The experimental method is tested with Uranium preliminary measurements. The reversible redox potentials (PuO 2 + and Pu 4+ /Pu 3+ ) are measured using the cyclic voltametric technique in perchloric media at several ionic strengths (from 0.5 to 3M) and temperatures (from 0 to 70 deg C). The Specific Interaction Theory (SIT) is used to measured activity coefficients and to extrapolate data to the standard conditions. The potentials variations versus temperature are linear in first approximation: the entropy changes are found constant from 0 to 70 deg C and the heat capacity changes are within uncertainties. The standard constant of PuO 2 + disproportionation into PuO 2 2+ and Pu 3+ is deduced from spectrophotometric measurements performed in perchloric media around pH=1 where Pu 4+ hydrolysis is discussed. The Pu non-reversible standard potentials (PuO 2 2+ /Pu 4+ for instance) are then calculated and validated with a spectrophotometric study of Pu 4+ formation from PuO 2 2+ and Pu 3+ in a 1M perchloric acidic solution. The Pu(VI/V) redox potential, activity coefficients and entropies are measured using the same technique in concentrated carbonate media. The limiting complex standard formation constants and the redox potential shifts (between acidic and carbonate media) are then discussed among the U, Np, Pu and Am actinides. A spectrophotometric study of the equilibrium between the complexes with 5 and 4 carbonate ligands allowed to measure Pu(IV) limiting complex stability at several ionic strengths. (author). 26 tabs., 46 figs., 95 refs

Influence of carbon source and inoculum type on anaerobic biomass adhesion on polyurethane foam in reactors fed with acid mine drainage.

Science.gov (United States)

Rodriguez, Renata P; Zaiat, Marcelo

2011-04-01

This paper analyzes the influence of carbon source and inoculum origin on the dynamics of biomass adhesion to an inert support in anaerobic reactors fed with acid mine drainage. Formic acid, lactic acid and ethanol were used as carbon sources. Two different inocula were evaluated: one taken from an UASB reactor and other from the sediment of a uranium mine. The values of average colonization rates and the maximum biomass concentration (C(max)) were inversely proportional to the number of carbon atoms in each substrate. The highest C(max) value (0.35 g TVS g(-1) foam) was observed with formic acid and anaerobic sludge as inoculum. Maximum colonization rates (v(max)) were strongly influenced by the type of inoculum when ethanol and lactic acid were used. For both carbon sources, the use of mine sediment as inoculum resulted in a v(max) of 0.013 g TVS g(-1) foam day(-1), whereas 0.024 g TVS g(-1) foam day(-1) was achieved with anaerobic sludge. Copyright © 2011 Elsevier Ltd. All rights reserved.

Effect of organic acids traces on the carbon steel corrosion behavior

International Nuclear Information System (INIS)

Stefanescu, D.; Radulescu; Mogosan, S.

2009-01-01

There are many different ways in which organic matter may get in water-steam cycles. One important pathway is constituted by organic matter admitted into the system by chemical make-up water under standard operation conditions (without inverse osmosis). The high molecular weight organic matter, in particularly polysaccharides are broken in organic acids, in particular acetic and formic acid. This paper presents an overview of the investigations undertaken referring to the behavior SA106 gr. B mild steel in secondary circuit aqueous environment contaminated with formic and acetic acid traces. The samples were filmed in static autoclaves in operation conditions of secondary circuit, in contaminated environment and after that they were investigated using metallographic microscopy and SEM. In addition, an electrochemical technique videlicet impedance spectroscopy (EIS) was used to investigate the corrosion behavior of SA106 gr. B carbon steel in secondary circuit medium contaminated with formic and acetic acid traces. (authors)

Adsorption of clofibric acid and ketoprofen onto powdered activated carbon: effect of natural organic matter.

Science.gov (United States)

Gao, Yaohuan; Deshusses, Marc A

2011-12-01

The adsorption of two acidic pharmaceutically active compounds (PhACs), clofibric acid and ketoprofen, onto powdered activated carbon (PAC) was investigated with a particular focus on the influence of natural organic matter (NOM) on the adsorption of the PhACs. Suwannee River humic acids (SRHAs) were used as a substitute for NOM. Batch adsorption experiments were conducted to obtain adsorption kinetics and adsorption isotherms with and without SRHAs in the system. The adsorption isotherms and adsorption kinetics showed that the adsorption ofclofibric acid was not significantly affected by the presence of SRHAs at a concentration of 5 mg (as carbon) L(-1). An adsorption capacity of 70 to 140 mg g(-1) was observed and equilibrium was reached within 48 h. In contrast, the adsorption of ketoprofen was markedly decreased (from about 120 mg g(-1) to 70-100 mg g(-1)) in the presence of SRHAs. Higher initial concentrations of clofibric acid than ketoprofen during testing may explain the different behaviours that were observed. Also, the more hydrophobic ketoprofen molecules may have less affinity for PAC when humic acids (which are hydrophilic) are present. The possible intermolecular forces that could account for the different behaviour of clofibric acid and ketoprofen adsorption onto PAC are discussed. In particular, the relevance of electrostatic forces, electron donor-acceptor interaction, hydrogen bonding and London dispersion forces are discussed

Highly selective determination of dopamine in the presence of ascorbic acid and serotonin at glassy carbon electrodes modified with carbon nanotubes dispersed in polyethylenimine.

Science.gov (United States)

Rodríguez, Marcela C; Rubianes, María D; Rivas, Gustavo A

2008-11-01

We report the highly selective and sensitive voltammetric dopamine quantification in the presence of ascorbic acid and serotonin by using glassy carbon electrodes modified with a dispersion of multi-wall carbon nanotubes (MWCNT) in polyethylenimine, PEI (GCE/MWCNT-PEI). The electrocatalytic activity of the MWCNT deposited on the glassy carbon electrode has allowed an important decrease in the overvoltages for the oxidation of ascorbic acid and dopamine, making possible a clear definition of dopamine, serotonin and ascorbic acid oxidation processes. The sensitivities for dopamine in the presence and absence of 1.0 mM ascorbic acid and serotonin were (2.18 +/- 0.03) x 10(5) microAM(-1) (r = 0.9998); and (2.10 +/- 0.07) x 10(5) miroAM(-1) (r=0.9985), respectively, demonstrating the excellent performance of the GCE/MWCNT-PEI. The detection limit for dopamine in the mixture was 9.2 x 10(-7) M. The R. S. D. for the determination of 50 microM dopamine using four different electrodes was 3.9% when modified with the same MWCNT/PEI dispersion, and 4.6% when using four different dispersions. The modified electrode has been successfully applied for recovery assays of dopamine in human blood serum. Therefore, the new sensor represents an interesting and promising alternative for the electrochemical quantification of neurotransmitters and other analytes of clinical interest.

Selection of organic acid leaching reagent for recovery of zinc and manganese from zinc-carbon and alkaline spent batteries

Science.gov (United States)

Yuliusman; Amiliana, R. A.; Wulandari, P. T.; Ramadhan, I. T.; Kusumadewi, F. A.

2018-03-01

Zinc-carbon and alkaline batteries are often used in electronic equipment that requires small quantities of power. The waste from these batteries contains valuable metals, such as zinc and manganese, that are needed in many industries and can pollute the environment if not treated properly. This paper concerns the recovery of zinc and manganese metals from zinc-carbon and alkaline spent batteries with leaching method and using organic acid as the environmental friendly leaching reagent. Three different organic acids, namely citric acid, malic acid and aspartic acid, were used as leaching reagents and compared with sulfuric acid as non-organic acid reagents that often used for leaching. The presence of hydrogen peroxide as manganese reducers was investigated for both organic and non-organic leaching reagents. The result showed that citric acid can recover 64.37% Zinc and 51.32% Manganese, while malic acid and aspartic acid could recover less than these. Hydrogen peroxide gave the significant effect for leaching manganese with non-organic acid, but not with organic acid.

Radioiodine uptake following iodine-131 therapy for Graves' disease: an early indicator of need for retreatment

Energy Technology Data Exchange (ETDEWEB)

Carpentier, W.R.; Gilliland, P.F.; Piziak, V.K.; Petty, F.C.; McConnell, B.G.; Verdonk, C.A.; Ibarra, J.D.; Thompson, J.Q.

1989-01-01

Forty-five patients with Graves' disease were studied prospectively to determine if 24-hour I-131 uptake measurements alone or in combination with serum thyroid hormone levels at six weeks would determine the necessity for retreatment of the thyrotoxicosis. All patients with an I-131 uptake greater than 30% at six weeks required retreatment. No patient with an I-131 uptake of less than 15% required retreatment. Patients with uptakes between 15% and 30% were variable. An elevated free thyroxin index at 6 weeks is not helpful to determine which patients will remain thyrotoxic. Patients with a free thyroxin index within the normal range at six weeks can be predicted to be euthyroid by 12 weeks if their 24-hour I-131 uptake is between 15% and 30% and to be hypothyroid if their 24-hour I-131 uptake is below 15%. There was no difference between patient groups treated initially with antithyroid medication and those who were not.

Development of a Method to Isolate Glutamic Acid from Foodstuffs for a Precise Determination of Their Stable Carbon Isotope Ratio.

Science.gov (United States)

Kobayashi, Kazuhiro; Tanaka, Masaharu; Yatsukawa, Yoichi; Tanabe, Soichi; Tanaka, Mitsuru; Ohkouchi, Naohiko

2018-01-01

Recent growing health awareness is leading to increasingly conscious decisions by consumers regarding the production and traceability of food. Stable isotopic compositions provide useful information for tracing the origin of foodstuffs and processes of food production. Plants exhibit different ratios of stable carbon isotopes (δ 13 C) because they utilized different photosynthetic (carbon fixation) pathways and grow in various environments. The origins of glutamic acid in foodstuffs can be differentiated on the basis of these photosynthetic characteristics. Here, we have developed a method to isolate glutamic acid in foodstuffs for determining the δ 13 C value by elemental analyzer-isotope-ratio mass spectrometry (EA/IRMS) without unintended isotopic fractionation. Briefly, following acid-hydrolysis, samples were defatted and passed through activated carbon and a cation-exchange column. Then, glutamic acid was isolated using preparative HPLC. This method is applicable to measuring, with a low standard deviation, the δ 13 C values of glutamic acid from foodstuffs derived from C3 and C4 plants and marine algae.

Electroplated reticulated vitreous carbon current collectors for lead-acid batteries: opportunities and challenges

Science.gov (United States)

Gyenge, Elod; Jung, Joey; Mahato, Basanta

Reticulated, open-cell structures based on vitreous carbon substrates electroplated with a Pb-Sn (1 wt.%) alloy were investigated as current collectors for lead-acid batteries. Scanning and backscattered electron microscopy, cyclic voltammetry, anodic polarization and flooded 2 V single-cell battery testing was employed to characterize the performance of the proposed collectors. A battery equipped with pasted electroplated reticulated vitreous carbon (RVC) electrodes of 137 cm 2 geometric area, at the time of manuscript submission, completed 500 cycles and over 1500 h of continuous operation. The cycling involved discharges at 63 A kg PAM-1 corresponding to a nominal 0.75 h rate and a positive active mass (PAM) utilization efficiency of 21%. The charging protocol was composed of two voltage limited (i.e. 2.6 V/cell), constant current steps of 35 and 9.5 A kg PAM-1, respectively, with a total duration of about 2 h. The charge factor was 1.05-1.15. The observed cycling behavior in conjunction with the versatility of electrodeposition to produce application-dependent optimized lead alloy coating thickness and composition shows promise for the development of lead-acid batteries using electroplated reticulated vitreous carbon collectors.

Bienzymatic Acetylcholinesterase and Choline Oxidase Immobilized Biosensor Based on a Phenyl Carboxylic Acid-Grafted Multiwalled Carbon Nanotube

Directory of Open Access Journals (Sweden)

So-Ra Lee

2014-01-01

Full Text Available Bienzymatic acetylcholinesterase (AChE and choline oxidase (ChOx immobilized biosensor based on a phenyl carboxylic acid-grafted multiwalled carbon nanotube (MWNT modified glass carbon electrode (GCE and carbon-screen printed electrode (SPE was fabricated for acetylcholine detection in human blood samples. Phenyl carboxylic acid-modified MWNT supports were prepared by electrochemical polymerization of 4-carboxyphenyl diazonium salts, which were synthesized by an amine group and sodium nitrite, on the surface of the MWNT-modified GCE and SPE in 0.1 M PBS. The successful fabrication of the AChE-ChOx-immobilized biosensor was confirmed via scanning electron microscopy (SEM, X-ray photoelectron spectroscopy (XPS, electrochemical impedance spectroscopy (EIS, and cyclic voltammetry (CV. The sensing range of the biosensor based on a GCE and SPE was 1.0~10 μM and 10~100 μM, respectively. The interfering effect of 0.1 M L-ascorbic acid, 0.1 M L-cysteine, and 0.1 M uric acid to 0.1 M acetylcholine was 3.00%, 9.00%, and 3.00%, respectively. Acetylcholine in a human blood sample was detected by the AChE-ChOx-immobilized biosensor.

Risk factors for treatment default among re-treatment tuberculosis patients in India, 2006.

Science.gov (United States)

Jha, Ugra Mohan; Satyanarayana, Srinath; Dewan, Puneet K; Chadha, Sarabjit; Wares, Fraser; Sahu, Suvanand; Gupta, Devesh; Chauhan, L S

2010-01-25

Under India's Revised National Tuberculosis Control Programme (RNTCP), >15% of previously-treated patients in the reported 2006 patient cohort defaulted from anti-tuberculosis treatment. To assess the timing, characteristics, and risk factors for default amongst re-treatment TB patients. For this case-control study, in 90 randomly-selected programme units treatment records were abstracted from all 2006 defaulters from the RNTCP re-treatment regimen (cases), with one consecutively-selected non-defaulter per case. Patients who interrupted anti-tuberculosis treatment for >2 months were classified as defaulters. 1,141 defaulters and 1,189 non-defaulters were included. The median duration of treatment prior to default was 81 days (25%-75% interquartile range 44-117 days) and documented retrieval efforts after treatment interruption were inadequate. Defaulters were more likely to have been male (adjusted odds ratio [aOR] 1.4, 95% confidence interval [CI] 1.2-1.7), have previously defaulted anti-tuberculosis treatment (aOR 1.3 95%CI 1.1-1.6], have previous treatment from non-RNTCP providers (AOR 1.3, 95%CI 1.0-1.6], or have public health facility-based treatment observation (aOR 1.3, 95%CI 1.1-1.6). Amongst the large number of re-treatment patients in India, default occurs early and often. Improved pre-treatment counseling and community-based treatment provision may reduce default rates. Efforts to retrieve treatment interrupters prior to default require strengthening.

Adsorption of NI (II on activated Carbon of Coconut shell Chemicaly Modifieded with Acid Nitric Solutions

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Mónica Hernández-Rodríguez

2017-01-01

Full Text Available In the research the effect of modification of coconut shell activated carbon with diluted solutions of nitric acid, in its chemical characteristics and removal capacity of the nickel (II ions present in modeling solutions of sulfates with similar characteristics to the acid liquor waste of the nickel industry, was studied. The characterization of the adsorbent material evidenced that the modification process increases the superficial acids groups according with the increase of acid nitric concentration employee in the treatment. The adsorption equilibrium tests, carried out with metallic species solutions at concentrations between 0,5 and 3,5 g/L evidenced that the process is described by Freundlich model. The effect of chemical modification of the adsorbent material in adsorption capacity of nickel (II ions was evaluated using a traditional experimental design at pH of 1,2 and 6,9 units, obtaining that the increase of acid groups in the carbon surface causes an increase of adsorption capacity and removal percentages of nickel (II, due to specific interactions of these groups with the metal cations.

ORIGIN OF PALMITIC ACID CARBON IN PALMITATES FORMED FROM HEXADECANE-1-C14 AND TETRADECANE-1-C14 BY MICROCOCCUS CERIFICANS

Science.gov (United States)

Finnerty, W. R.; Kallio, R. E.

1964-01-01

Finnerty, W. R. (University of Iowa, Iowa City), and R. E. Kallio. Origin of palmitic acid carbon in palmitates formed from hexadecane-1-C14 and tetradecane-1-C14 by Micrococcus cerificans. J. Bacteriol. 87:1261–1265. 1964.—Degradation of the palmitic acid moiety of cetyl palmitate and myristyl palmitate formed from hexadecane-1-C14 and tetradecane-1-C14 by Micrococcus cerificans was carried out. The patterns of C14 labeling in palmitic acid from cetyl palmitate showed that hexadecane is oxidized at the C1 position, and cetyl alcohol and palmitic acid thus formed are directly esterified. Palmitic acid arising from tetradecane and esterified to tetradecanol appeared to have been synthesized by the addition of two carbon atoms to an existing 14-carbon atom skeleton. Considerable mixing of C14 occurred in the C1 and C2 positions of palmitic acid thus synthesized. PMID:14188700

Methanesulfonic acid-assisted synthesis of N/S co-doped hierarchically porous carbon for high performance supercapacitors

Science.gov (United States)

Huo, Silu; Liu, Mingquan; Wu, Linlin; Liu, Mingjie; Xu, Min; Ni, Wei; Yan, Yi-Ming

2018-05-01

Nitrogen and sulfur co-doped carbons are considered as electrode materials for high performance supercapacitors, while their further development is still limited by complicated synthesis procedure, unsatisfied structure and low energy density. Developing a simple synthetic strategy to obtain rationally structured carbon materials and high supercapacitor performance is remaining a grand challenge. Herein, we describe the synthesis of nitrogen and sulfur co-doped hierarchical porous carbons as high performance supercapacitors electrode by a methanesulfonic acid-assisted one-step carbonization and activation of the freeze-dried precursors mixture. The as-prepared carbon material not only exhibits ideally hierarchical pores, but also realizes uniform nitrogen and sulfur co-doping. In 6.0 M KOH electrolyte, the material can achieve a high specific capacitance of 272 F g-1 at 1.0 A g-1 and a promising rate performance retaining 172 F g-1 even at 100 A g-1. Moreover, a fabricated symmetric supercapacitor based on as-prepared nitrogen and sulfur co-doped hierarchical porous carbon delivers high energy densities of 12.4 W h kg-1 and 8.0 W h kg-1 in 6.0 M KOH liquid and KOH/PVA solid-state electrolytes, respectively. This work presents a simple and effective methanesulfonic acid-assisted approach for mass production of heteroatomic doping hierarchical porous carbons for future energy storage applications.

Acetaldehyde stimulation of net gluconeogenic carbon movement from applied malic acid in tomato fruit pericarp tissue

International Nuclear Information System (INIS)

Halinska, A.; Frenkel, C.

1991-01-01

Applied acetaldehyde is known to lead to sugar accumulation in fruit including tomatoes (Lycopersicon esculentum) presumably due to stimulation of gluconeogenesis. This conjecture was examined using tomato fruit pericarp discs as a test system and applied l-[U- 14 C]malic acid as the source for gluconeogenic carbon mobilization. Results indicate that malic and perhaps other organic acids are carbon sources for gluconeogenesis occurring normally in ripening tomatoes. The process is stimulated by acetaldehyde apparently by attenuating the fructose-2,6-biphosphate levels. The mode of the acetaldehyde regulation of fructose-2,6-biphosphate metabolism awaits clarification

Poly(lactic acid Composites Containing Carbon-Based Nanomaterials: A Review

Directory of Open Access Journals (Sweden)

Carolina Gonçalves

2017-07-01

Full Text Available Poly(lactic acid (PLA is a green alternative to petrochemical commodity plastics, used in packaging, agricultural products, disposable materials, textiles, and automotive composites. It is also approved by regulatory authorities for several biomedical applications. However, for some uses it is required that some of its properties be improved, namely in terms of thermo-mechanical and electrical performance. The incorporation of nanofillers is a common approach to attain this goal. The outstanding properties of carbon-based nanomaterials (CBN have caused a surge in research works dealing with PLA/CBN composites. The available information is compiled and reviewed, focusing on PLA/CNT (carbon nanotubes and PLA/GBM (graphene-based materials composites. The production methods, and the effects of CBN loading on PLA properties, namely mechanical, thermal, electrical, and biological, are discussed.

Simple quantification of surface carboxylic acids on chemically oxidized multi-walled carbon nanotubes

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Gong, Hyejin; Kim, Seong-Taek; Lee, Jong Doo; Yim, Sanggyu

2013-02-01

The surface of multi-walled carbon nanotube (MWCNT) was chemically oxidized using nitric acid and sulfuric-nitric acid mixtures. Thermogravimetric analysis, transmission electron microscopy and infrared spectroscopy revealed that the use of acid mixtures led to higher degree of oxidation. More quantitative identification of surface carboxylic acids was carried out using X-ray photoelectron spectroscopy (XPS) and acid-base titration. However, these techniques are costly and require very long analysis times to promptly respond to the extent of the reaction. We propose a much simpler method using pH measurements and pre-determined pKa value in order to estimate the concentration of carboxylic acids on the oxidized MWCNT surfaces. The results from this technique were consistent with those obtained from XPS and titration, and it is expected that this simple quantification method can provide a cheap and fast way to monitor and control the oxidation reaction of MWCNT.

Formic Acid Oxidation over Hierarchical Porous Carbon Containing PtPd Catalysts

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Elena Pastor

2013-10-01

Full Text Available The use of high surface monolithic carbon as support for catalysts offers important advantage, such as elimination of the ohmic drop originated in the interparticle contact and improved mass transport by ad-hoc pore design. Moreover, the approach discussed here has the advantage that it allows the synthesis of materials having a multimodal porous size distribution, with each pore size contributing to the desired properties. On the other hand, the monolithic nature of the porous support also imposes new challenges for metal loading. In this work, the use of Hierarchical Porous Carbon (HPC as support for PtPd nanoparticles was explored. Three hierarchical porous carbon samples (denoted as HPC-300, HPC-400 and HPC-500 with main pore size around 300, 400 and 500 nm respectively, are used as porous support. PtPd nanoparticles were loaded by impregnation and subsequent chemical reduction with NaBH4. The resulting material was characterized by EDX, XRD and conventional electrochemical techniques. The catalytic activity toward formic acid and methanol electrooxidation was evaluated by electrochemical methods, and the results compared with commercial carbon supported PtPd. The Hierarchical Porous Carbon support discussed here seems to be promising for use in DFAFC anodes.

Linking Backbarrier Lacustrine Stratigraphy with Spatial Dynamics of Shoreline Retreat in a Rapidly Subsiding Region of the Mississippi River Delta

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Dietz, M.; Liu, K. B.; Bianchette, T. A.; Yao, Q.

2017-12-01

The shoreline along the northern Gulf of Mexico is rapidly retreating as coastal features of abandoned Mississippi River delta complexes erode and subside. Bay Champagne is located in the Caminada-Moreau headland, a region of shoreline west of the currently active delta that has one of the highest rates of retreat and land loss. As a result, this site has transitioned from a stable, circular inland lake several kilometers from the shore to a frequently perturbed, semi-circular backbarrier lagoon, making it ideal to study the environmental effects of progressive land loss. Analyses of clastic layers in a series of sediment cores collected at this site over the past decade indicate the lake was less perturbed in the past and has become increasingly more sensitive to marine incursion events caused by tropical cyclones. Geochemical and pollen analyses of these cores also reveal profound changes in environmental and chemical conditions in Bay Champagne over the past century as the shoreline has retreated. Through relating stratigraphy to spatial changes observed from satellite imagery, this study attempts to identify the tipping point at which Bay Champagne began the transition from an inland lake to a backbarrier environment, and to determine the rate at which this transition occurred. Results will be used to develop a model of the environmental transition experienced by a rapidly retreating coastline and to predict how other regions of the Mississippi River deltaic system could respond to future shoreline retreat.

The use of social Stegodyphus spider retreats as nest-lining by pale ...

African Journals Online (AJOL)

The pale chanting-goshawk (Melierax canorus) incorporates silk nests (hereafter 'retreats') of the social spider Stegodyphus dumicola (Araneae: Eresidae) in the construction of the nest-lining of their own nests. This study investigates whether pale chanting-goshawks in the Little Karoo, South Africa, show a preference for ...

Corrosion resistance of Ultra-Low-Carbon 19% Cr-11% Ni stainless steel for nuclear fuel reprocessing plants in nitric acid

International Nuclear Information System (INIS)

Ariga, Tamako; Takagi, Yoshio; Inazumi, Toru; Masamura, Katsumi; Sukekawa, M.

1995-01-01

An Ultra-Low-Carbon 19% Cr-11% Ni Stainless Steels used in nuclear fuel reprocessing plants where highly corrosion resistance in nitric acid is required has been developed. This steel has optimized the chemistry composition to decrease inclusions and deformation-induced martensitic transformation. The formation of deformation-induced martensite has the potential danger of accelerating corrosion in nitric acid. In this paper, effects of cold reduction and martensitic transformation on corrosion resistance of Ultra-Low-Carbon Stainless Steels in nitric acid are discussed. The developed steel showed excellent corrosion resistance during long-term exposure to nitric acid. (author)

Iodide-photocatalyzed reduction of carbon dioxide to formic acid with thiols and hydrogen sulfide

OpenAIRE

Berton, Mateo Otao; Mello, Rossella C. C.; González Núñez, María Elena

2016-01-01

The photolysis of iodide anions promotes the reaction of carbon dioxide with hydrogen sulfide or thiols to quantitatively yield formic acid and sulfur or disulfides. The reaction proceeds in acetonitrile and aqueous solutions, at atmospheric pressure and room temperature by irradiation using a low-pressure mercury lamp. This transition-metal-free photocatalytic process for CO2 capture coupled with H2S removal may have been relevant as a prebiotic carbon dioxide fixation.

A novel l-leucine modified Sol-Gel-Carbon electrode for simultaneous electrochemical detection of homovanillic acid, dopamine and uric acid in neuroblastoma diagnosis.

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Khamlichi, Redouan El; Bouchta, Dounia; Anouar, El Hassane; Atia, Mounia Ben; Attar, Aisha; Choukairi, Mohamed; Tazi, Saloua; Ihssane, Raissouni; Faiza, Chaoukat; Khalid, Draoui; Khalid, Riffi Temsamani

2017-02-01

Neuroblastoma is a pediatric neuroblastic tumor arising in the sympathetic nervous crest cells. A high grade of Neuroblastoma is characterized by a high urinary excretion of homovanillic acid and dopamine. In this work l-leucine modified Sol-Gel-Carbon electrode was used for a sensitive voltammetric determination of homovanillic acid and dopamine in urine. The electrochemical response characteristics were investigated by cyclic and differential pulse voltammetry; the modified electrode has shown an increase in the effective area of up to 40%, a well-separated oxidation peaks and an excellent electrocatalytic activity. High sensitivity and selectivity in the linear range of 0,4-100μML -1 of homovanillic acid and 10-120μML -1 of dopamine were also obtained. Moreover, a sub-micromolar limit of detection of 0.1μM for homovanillic acid and 1.0μM for the dopamine was achieved. Indeed, high reproducibility with simple preparation and regeneration of the electrode surface made this electrode very suitable for the determination of homovanillic acid and dopamine in pharmaceutical and clinical preparations. The mechanism of homovanillic acid and the electrochemical oxidation at l-leucine modified Sol-Gel-Carbon electrode is described out the B3P86/6-31+G(d,p) level of theory as implemented in Gaussian software. Copyright © 2016 Elsevier B.V. All rights reserved.

Influence of peracetic acid modification on the physicochemical properties of activated carbon and its performance in the ozone-catalytic oxidation of gaseous benzene

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Fang, Ruimei; Huang, Haibao; Huang, Wenjun; Ji, Jian; Feng, Qiuyu; Shu, Yajie; Zhan, Yujie; Liu, Gaoyuan; Xie, Ruijie

2017-10-01

Coal based activated carbon (AC) was pretreated by peracetic acid solution and used for supporting Mn catalyst towards oxidation of gaseous benzene by catalytic ozonation. The as-obtained activated carbon was characterized by XPS, BET, SEM, and TG technologies. It indicates that peracetic acid solution modification not only raised the quantity of chemisorbed oxygen or water, and hydroxyl group on activated carbon material surface, but also increased the specific surface area and benzene adsorption capacity of activated carbon. Benzene could be completely removed in 300 min and CO2 selectivity reached to 61.9% over Mn/AC-modified catalyst. A possible catalytic ozonation mechanism of activated carbon which was treated by peracetic acid solution supported Mn catalyst for oxidation of benzene was proposed.

Diamond-like carbon coating under oleic acid lubrication: Evidence for graphene oxide formation in superlow friction

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de Barros Bouchet, Maria Isabel; Martin, Jean Michel; Avila, José; Kano, Makoto; Yoshida, Kentaro; Tsuruda, Takeshi; Bai, Shandan; Higuchi, Yuji; Ozawa, Nobuki; Kubo, Momoji; Asensio, Maria C.

2017-04-01

The achievement of the superlubricity regime, with a friction coefficient below 0.01, is the Holy Grail of many tribological applications, with the potential to have a remarkable impact on economic and environmental issues. Based on a combined high-resolution photoemission and soft X-ray absorption study, we report that superlubricity can be realized for engineering applications in bearing steel coated with ultra-smooth tetrahedral amorphous carbon (ta-C) under oleic acid lubrication. The results show that tribochemical reactions promoted by the oil lubrication generate strong structural changes in the carbon hybridization of the ta-C hydrogen-free carbon, with initially high sp3 content. Interestingly, the macroscopic superlow friction regime of moving mechanical assemblies coated with ta-C can be attributed to a few partially oxidized graphene-like sheets, with a thickness of not more than 1 nm, formed at the surface inside the wear scar. The sp2 planar carbon and oxygen-derived species are the hallmark of these mesoscopic surface structures created on top of colliding asperities as a result of the tribochemical reactions induced by the oleic acid lubrication. Atomistic simulations elucidate the tribo-formation of such graphene-like structures, providing the link between the overall atomistic mechanism and the macroscopic experimental observations of green superlubricity in the investigated ta-C/oleic acid tribological systems.

Interest in health promotion among Korean American Seventh-day Adventists attending a religious retreat.

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Jo, Angela M; Maxwell, Annette E; Choi, Sunhye; Bastani, Roshan

2012-01-01

Little is known about interest in faith-based health promotion programs among Asian American populations. Among the Christian denominations, the Seventh-day Adventist (SDA) church is known to place a strong doctrinal emphasis on health. To understand appropriate ways to develop and implement health promotion programs and to conduct research among Korean American SDAs. We collaborated with the North American Division of Korean SDA Churches which sponsors annual week-long religious retreats for their church members. We developed and administered a 10-page questionnaire at their 2009 retreat in order to assess socio-demographic and church characteristics, religiosity, perceived relationship between health and religion, and interest and preferences for church-based health promotion programs. Overall, 223 participants completed our survey (123 in Korean and 100 in English). The sample consisted of regular churchgoers who were involved in a variety of helping activities, and many holding leadership positions in their home churches. The vast majority was interested in receiving health information at church (80%) in the form of seminars, cooking classes and workshops (50-60%). Fewer respondents were interested in support groups (27%). Some interests and preferences differed between English and Korean language groups. Korean American SDA church retreat participants from a large geographic area are very interested in receiving health information and promoting health at their churches and can potentially serve as "agents of influence" in their respective communities.

Yoga, Meditation and Mind-Body Health: Increased BDNF, Cortisol Awakening Response, and Altered Inflammatory Marker Expression after a 3-Month Yoga and Meditation Retreat

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B. Rael Cahn

2017-06-01

Full Text Available Thirty-eight individuals (mean age: 34.8 years old participating in a 3-month yoga and meditation retreat were assessed before and after the intervention for psychometric measures, brain derived neurotrophic factor (BDNF, circadian salivary cortisol levels, and pro- and anti-inflammatory cytokines. Participation in the retreat was found to be associated with decreases in self-reported anxiety and depression as well as increases in mindfulness. As hypothesized, increases in the plasma levels of BDNF and increases in the magnitude of the cortisol awakening response (CAR were also observed. The normalized change in BDNF levels was inversely correlated with BSI-18 anxiety scores at both the pre-retreat (r = 0.40, p < 0.05 and post-retreat (r = 0.52, p < 0.005 such that those with greater anxiety scores tended to exhibit smaller pre- to post-retreat increases in plasma BDNF levels. In line with a hypothesized decrease in inflammatory processes resulting from the yoga and meditation practices, we found that the plasma level of the anti-inflammatory cytokine Interleukin-10 was increased and the pro-inflammatory cytokine Interleukin-12 was reduced after the retreat. Contrary to our initial hypotheses, plasma levels of other pro-inflammatory cytokines, including Interferon Gamma (IFN-γ, Tumor Necrosis Factor (TNF-α, Interleukin-1β (IL-1β, Interleukin-6 (IL-6, and Interleukin-8 (IL-8 were increased after the retreat. Given evidence from previous studies of the positive effects of meditative practices on mental fitness, autonomic homeostasis and inflammatory status, we hypothesize that these findings are related to the meditative practices throughout the retreat; however, some of the observed changes may also be related to other aspects of the retreat such as physical exercise-related components of the yoga practice and diet. We hypothesize that the patterns of change observed here reflect mind-body integration and well-being. The increased BDNF levels

Biomediated Precipitation of Calcium Carbonate in a Slightly Acidic Hot Spring

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Jiang, L.

2015-12-01

A slightly acidic hot spring named "Female Tower" (T=73.5 °C, pH=6.64) is located in the Jifei Geothermal Field, Yunnan Province, Southwest China. The precipitates in the hot spring are composed of large amounts of calcite, aragonite, and sulfur. Scanning electron microscopy (SEM) analyses revealed that the microbial mats were formed of various coccoid, rod-shaped, and filamentous microbes. Transmission electron microscopy (TEM) showed that the intracellular sulfur granules were commonly associated with these microbes. A culture-independent molecular phylogenetic analysis demonstrated that the majority of the bacteria in the spring were sulfur-oxidizing bacteria. In the spring water, H2S concentration was up to 60 ppm, while SO42- concentration was only about 10 ppm. We speculated that H2S might be utilized by sulfur-oxidizing bacteria in this hot spring water, leading to the intracellular formation of sulfur granules. In the meantime, this reaction increased the pH in the micron-scale microdomains, which fostered the precipitation of calcium carbonate in the microbial mats. The results of this study indicated that the sulfur-oxidizing bacteria could play an important role in calcium carbonate precipitation in slightly acidic hot spring environments.

Abscisic acid as a factor in regulation of photosynthetic carbon metabolism of pea seedlings

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Maria Faltynowicz

2014-01-01

Full Text Available The influence of abscisic acid (ABA on carbon metabolism and the activity of ribulosebisphosphate (RuBP and phosphoenolpyruvate (PEP carboxylases in 8-day-old pea seedlings was investigated. It was endeavoured to correlate the changes observed in metabolic processes with the endogenous ABA level. In plants treated with ABA incorporation of labeled carbon into sucrose, glucose, fructose and sugar phosphates was depressed, while 14C incorporation into starch, ribulose and malic acid was enhanced. The activity of RuBP carboxylase was considerably lowered, whereas that of PEP carboxylase was slightly increased. It is considered that inhibition of photosynthesis due to the action of ABA is caused to a great extent by the obstruction of the C-3 pathway and reduced activity of RuBP carboxylase, whereas (β-carboxylation was not blocked.

Elevated carbon dioxide increases salicylic acid in Glycine max.

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Casteel, Clare L; Segal, Lauren M; Niziolek, Olivia K; Berenbaum, May R; DeLucia, Evan H

2012-12-01

Concentrations of carbon dioxide (CO(2)) are increasing in the atmosphere, affecting soybean (Glycine max L.) phytohormone signaling and herbivore resistance. Whether the impact of elevated CO(2) on phytohormones and induced defenses is a generalized response within this species is an open question. We examined jasmonic acid (JA) and salicylic acid (SA) under ambient and elevated CO(2) concentrations with and without Japanese beetle (Popillia japonica Newman) damage and artificial damage across six soybean cultivars (HS93-4118, Pana, IA 3010, Loda, LN97-15076, and Dwight). Elevated CO(2) reduced constitutive levels of JA and related transcripts in some but not all soybean cultivars. In contrast to the variation in JA, constitutive levels of salicylic were increased universally among soybean cultivars grown under elevated CO(2). Variation in hormonal signaling may underpin observed variation in the response of insect herbivores and pathogens to plants grown under elevated CO(2).

Tracing carbon sources through aquatic and terrestrial food webs using amino acid stable isotope fingerprinting.

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Thomas Larsen

Full Text Available Tracing the origin of nutrients is a fundamental goal of food web research but methodological issues associated with current research techniques such as using stable isotope ratios of bulk tissue can lead to confounding results. We investigated whether naturally occurring δ(13C patterns among amino acids (δ(13CAA could distinguish between multiple aquatic and terrestrial primary production sources. We found that δ(13CAA patterns in contrast to bulk δ(13C values distinguished between carbon derived from algae, seagrass, terrestrial plants, bacteria and fungi. Furthermore, we showed for two aquatic producers that their δ(13CAA patterns were largely unaffected by different environmental conditions despite substantial shifts in bulk δ(13C values. The potential of assessing the major carbon sources at the base of the food web was demonstrated for freshwater, pelagic, and estuarine consumers; consumer δ(13C patterns of essential amino acids largely matched those of the dominant primary producers in each system. Since amino acids make up about half of organismal carbon, source diagnostic isotope fingerprints can be used as a new complementary approach to overcome some of the limitations of variable source bulk isotope values commonly encountered in estuarine areas and other complex environments with mixed aquatic and terrestrial inputs.

Tracing carbon sources through aquatic and terrestrial food webs using amino acid stable isotope fingerprinting.

Science.gov (United States)

Larsen, Thomas; Ventura, Marc; Andersen, Nils; O'Brien, Diane M; Piatkowski, Uwe; McCarthy, Matthew D

2013-01-01

Tracing the origin of nutrients is a fundamental goal of food web research but methodological issues associated with current research techniques such as using stable isotope ratios of bulk tissue can lead to confounding results. We investigated whether naturally occurring δ(13)C patterns among amino acids (δ(13)CAA) could distinguish between multiple aquatic and terrestrial primary production sources. We found that δ(13)CAA patterns in contrast to bulk δ(13)C values distinguished between carbon derived from algae, seagrass, terrestrial plants, bacteria and fungi. Furthermore, we showed for two aquatic producers that their δ(13)CAA patterns were largely unaffected by different environmental conditions despite substantial shifts in bulk δ(13)C values. The potential of assessing the major carbon sources at the base of the food web was demonstrated for freshwater, pelagic, and estuarine consumers; consumer δ(13)C patterns of essential amino acids largely matched those of the dominant primary producers in each system. Since amino acids make up about half of organismal carbon, source diagnostic isotope fingerprints can be used as a new complementary approach to overcome some of the limitations of variable source bulk isotope values commonly encountered in estuarine areas and other complex environments with mixed aquatic and terrestrial inputs.

Creating a specialist protein resource network: a meeting report for the protein bioinformatics and community resources retreat

DEFF Research Database (Denmark)

Babbitt, Patricia C.; Bagos, Pantelis G.; Bairoch, Amos

2015-01-01

During 11–12 August 2014, a Protein Bioinformatics and Community Resources Retreat was held at the Wellcome Trust Genome Campus in Hinxton, UK. This meeting brought together the principal investigators of several specialized protein resources (such as CAZy, TCDB and MEROPS) as well as those from...... protein databases from the large Bioinformatics centres (including UniProt and RefSeq). The retreat was divided into five sessions: (1) key challenges, (2) the databases represented, (3) best practices for maintenance and curation, (4) information flow to and from large data centers and (5) communication...

Determination of the conformation of 2-hydroxy- and 2-aminobenzoic acid dimers using 13C NMR and density functional theory/natural bond order analysis: the central importance of the carboxylic acid carbon.

Science.gov (United States)

Burnette, Ronald R; Weinhold, Frank

2006-07-20

The 13C chemical shift for the carboxylic acid carbon provides a powerful diagnostic probe to determine the preferred isomeric dimer structures of benzoic acid derivatives undergoing intra- and intermolecular H-bonding in the gas, solution and crystalline phases. We have employed hybrid density functional calculations and natural bond orbital analysis to elucidate the electronic origins of the observed 13C shieldings and their relationship to isomeric stability. We find that delocalizing interactions from the carbonyl oxygen lone pairs (nO) into vicinal carbon-oxygen and carbon-carbon antibonds (sigmaCO*,sigmaCC*) make critical contributions to the 13C shieldings, and these nO --> sigmaCO*, nO --> sigmaCC* interactions are in turn sensitive to the intramolecular interactions that dictate dimer structure and stability. The carboxyl carbon atom can thus serve as a useful detector of subtle structural and conformational features in this pharmacologically important class of carboxylic acid interactions.

High Acetic Acid Production Rate Obtained by Microbial Electrosynthesis from Carbon Dioxide.

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Jourdin, Ludovic; Grieger, Timothy; Monetti, Juliette; Flexer, Victoria; Freguia, Stefano; Lu, Yang; Chen, Jun; Romano, Mark; Wallace, Gordon G; Keller, Jurg

2015-11-17

High product specificity and production rate are regarded as key success parameters for large-scale applicability of a (bio)chemical reaction technology. Here, we report a significant performance enhancement in acetate formation from CO2, reaching comparable productivity levels as in industrial fermentation processes (volumetric production rate and product yield). A biocathode current density of -102 ± 1 A m(-2) and an acetic acid production rate of 685 ± 30 (g m(-2) day(-1)) have been achieved in this study. High recoveries of 94 ± 2% of the CO2 supplied as the sole carbon source and 100 ± 4% of electrons into the final product (acetic acid) were achieved after development of a mature biofilm, reaching an elevated product titer of up to 11 g L(-1). This high product specificity is remarkable for mixed microbial cultures, which would make the product downstream processing easier and the technology more attractive. This performance enhancement was enabled through the combination of a well-acclimatized and enriched microbial culture (very fast start-up after culture transfer), coupled with the use of a newly synthesized electrode material, EPD-3D. The throwing power of the electrophoretic deposition technique, a method suitable for large-scale production, was harnessed to form multiwalled carbon nanotube coatings onto reticulated vitreous carbon to generate a hierarchical porous structure.

Retreatment of patients with treatment failure of direct-acting antivirals: Focus on hepatitis C virus genotype 1b.

Science.gov (United States)

Kanda, Tatsuo; Nirei, Kazushige; Matsumoto, Naoki; Higuchi, Teruhisa; Nakamura, Hitomi; Yamagami, Hiroaki; Matsuoka, Shunichi; Moriyama, Mitsuhiko

2017-12-14

The recent development of direct-acting antiviral agents (DAAs) against hepatitis C virus (HCV) infection could lead to higher sustained virological response (SVR) rates, with shorter treatment durations and fewer adverse events compared with regimens that include interferon. However, a relatively small proportion of patients cannot achieve SVR in the first treatment, including DAAs with or without peginterferon and/or ribavirin. Although retreatment with a combination of DAAs should be conducted for these patients, it is more difficult to achieve SVR when retreating these patients because of resistance-associated substitutions (RASs) or treatment-emergent substitutions. In Japan, HCV genotype 1b (GT1b) is founded in 70% of HCV-infected individuals. In this minireview, we summarize the retreatment regimens and their SVR rates for HCV GT1b. It is important to avoid drugs that target the regions targeted by initial drugs, but next-generation combinations of DAAs, such as sofosbuvir/velpatasvir/voxilaprevir for 12 wk or glecaprevir/pibrentasvir for 12 wk, are proposed to be potential solution for the HCV GT1b-infected patients with treatment failure, mainly on a basis of targeting distinctive regions. Clinicians should follow the new information and resources for DAAs and select the proper combination of DAAs for the retreatment of HCV GT1b-infected patients with treatment failure.

Expression of Genes Encoding Enzymes Involved in the One Carbon Cycle in Rat Placenta is Determined by Maternal Micronutrients (Folic Acid, Vitamin B12 and Omega-3 Fatty Acids

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Vinita Khot

2014-01-01

Full Text Available We have reported that folic acid, vitamin B12, and omega-3 fatty acids are interlinked in the one carbon cycle and have implications for fetal programming. Our earlier studies demonstrate that an imbalance in maternal micronutrients influence long chain polyunsaturated fatty acid metabolism and global methylation in rat placenta. We hypothesize that these changes are mediated through micronutrient dependent regulation of enzymes in one carbon cycle. Pregnant dams were assigned to six dietary groups with varying folic acid and vitamin B12 levels. Vitamin B12 deficient groups were supplemented with omega-3 fatty acid. Placental mRNA levels of enzymes, levels of phospholipids, and glutathione were determined. Results suggest that maternal micronutrient imbalance (excess folic acid with vitamin B12 deficiency leads to lower mRNA levels of methylene tetrahydrofolate reductase (MTHFR and methionine synthase , but higher cystathionine b-synthase (CBS and Phosphatidylethanolamine-N-methyltransferase (PEMT as compared to control. Omega-3 supplementation normalized CBS and MTHFR mRNA levels. Increased placental phosphatidylethanolamine (PE, phosphatidylcholine (PC, in the same group was also observed. Our data suggests that adverse effects of a maternal micronutrient imbalanced diet may be due to differential regulation of key genes encoding enzymes in one carbon cycle and omega-3 supplementation may ameliorate most of these changes.

Removal of free fatty acid in Palm Fatty Acid Distillate using sulfonated carbon catalyst derived from biomass wastefor biodiesel production

Science.gov (United States)

Hidayat, Arif; Rochmadi; Wijaya, Karna; Budiman, Arief

2016-01-01

In this research, the esterification of PFAD using the sulfonatedcoconut shell biochar catalyst was studied. Carbon solid catalysts were prepared by a sulfonation of carbonized coconut shells. The performances of the catalysts were evaluated in terms of the reaction temperatures, the molar ratios of methanol to PFAD, the catalyst loading and the reaction times. The reusability of the solid acid carbon catalysts was also studied in this work. The results indicated that the FFA conversion was significantly increased with increasing catalyst loading and reaction times. It can be concluded that the optimal conditions were an PFAD to methanol molar ratio of 1:12, the amount of catalyst of 10%w, and reaction temperature of 60oC.At this optimum condition, the conversion to biodieselreached 88%.

The paradox of a long grounding during West Antarctic Ice Sheet retreat in Ross Sea.

Science.gov (United States)

Bart, Philip J; Krogmeier, Benjamin J; Bart, Manon P; Tulaczyk, Slawek

2017-04-28

Marine geological data show that the West Antarctic Ice Sheet (WAIS) advanced to the eastern Ross Sea shelf edge during the Last Glacial Maximum (LGM) and eventually retreated ~1000 km to the current grounding-line position on the inner shelf. During the early deglacial, the WAIS deposited a voluminous stack of overlapping grounding zone wedges (GZWs) on the outer shelf of the Whales Deep Basin. The large sediment volume of the GZW cluster suggests that the grounding-line position of the paleo-Bindschadler Ice Stream was relatively stationary for a significant time interval. We used an upper bound estimate of paleo-sediment flux to investigate the lower bound duration over which the ice stream would have deposited sediment to account for the GZW volume. Our calculations show that the cluster represents more than three millennia of ice-stream sedimentation. This long duration grounding was probably facilitated by rapid GZW growth. The subsequent punctuated large-distance (~200 km) grounding-line retreat may have been a highly non-linear ice sheet response to relatively continuous external forcing such as gradual climate warming or sea-level rise. These findings indicate that reliable predictions of future WAIS retreat may require incorporation of realistic calculations of sediment erosion, transport and deposition.

Dispersion state and humic acids concentration-dependent sorption of pyrene to carbon nanotubes

NARCIS (Netherlands)

Zhang, X.; Kah, M.; Jonker, M.T.O.; Hofmann, T.

2012-01-01

Sonication and humic acids (HA) are known to disperse carbon nanotube (CNT) suspensions, but potential effects on sorption of chemicals to CNTs remain poorly understood. We applied a passive sampling method to investigate the influence of dispersion/aggregation on sorption of pyrene to CNTs.

Long-term follow-up with Granulocyte and Monocyte Apheresis re-treatment in patients with chronically active inflammatory bowel disease

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Karlsson Mats

2010-07-01

Full Text Available Abstract Background Patients with IBD and chronic inflammation refractory to conventional therapy often demonstrate higher risk of serious complications. Combinations of immunosuppression and biological treatment as well as surgical intervention are often used in this patient group. Hence, there is need for additional treatment options. In this observational study, focused on re-treatment and long-term results, Granulocyte/Monocyte Adsorption (GMA, Adacolumn® treatment has been investigated to study efficacy, safety and quality of life in IBD-patients with chronic activity. Methods Fifteen patients with ulcerative colitis and 25 patients with Crohn's disease, both groups with chronically active inflammation refractory to conventional medication were included in this observational study. The patients received 5-10 GMA sessions, and the clinical activity was assessed at baseline, after each completed course, and at week 10 and 20 by disease activity index, endoscopy and quality of life evaluation. Relapsed patients were re-treated by GMA in this follow-up study up to 58 months. Results Clinical response was seen in 85% and complete remission in 65% of the patients. Ten patients in the UC-group (66% and 16 patients in the CD-group (64% maintained clinical and endoscopic remission for an average of 14 months. Fourteen patients who relapsed after showing initial remission were re-treated with GMA and 13 (93% went into a second remission. Following further relapses, all of seven patients were successfully re-treated for the third time, all of three patients for the fourth time and one for a fifth time. Conclusions IBD-patients with chronic inflammation despite conventional therapy seem to benefit from GMA. Re-treatment of relapsing remission patients seems to be effective.

Evidence for slow late-glacial ice retreat in the upper Rangitata Valley, South Island, New Zealand

Science.gov (United States)

Shulmeister, J.; Fink, D.; Winkler, S.; Thackray, G. D.; Borsellino, R.; Hemmingsen, M.; Rittenour, T. M.

2018-04-01

A suite of cosmogenic radionuclide ages taken from boulders on lateral and latero-terminal moraines in the Rangitata Valley, eastern South Island, New Zealand demonstrates that relatively thick ice occupied valley reaches inland of the Rangitata Gorge until c. 21 ka. Thereafter ice began to thin, and by c. 17 ka it had retreated 33 km up-valley of the Rangitata Gorge to the Butler-Brabazon Downs, a structurally created basin in the upper Rangitata Valley. Despite its magnitude, this retreat represents a minor ice volume reduction from 21 ka to 17 ka, and numerous lateral moraines preserved suggest a relatively gradual retreat over that 4 ka period. In contrast to records from adjacent valleys, there is no evidence for an ice-collapse at c. 18 ka. We argue that the Rangitata record constitutes a more direct record of glacial response to deglacial climate than other records where glacial dynamics were influenced by proglacial lake development, such as the Rakaia Valley to the North and the major valleys in the Mackenzie Basin to the south-west. Our data supports the concept of a gradual warming during the early deglaciation in the South Island New Zealand.

Seabed Gradient Controlling Onshore Transport Rates of Surf Sand during Beach Retreat by Sea Level Rise

Science.gov (United States)

Lee, Hee Jun; Yi, Hi-Il

2018-03-01

A simple relationship is proposed for the onshore transport rates of surf-zone sand to evaluate the beach retreat caused by sea level rise. It suggests that the preservation potential of surf sand is proportional inversely to the seabed gradient during beach retreat. According to this relationship, the erosional remnants of surf sand would be more readily developed on a gentler shelf collectively as transgressive sand sheets. This finding may explain the previous studies regarding the Korean shelves that proposed that the Holocene transgressive sand sheets (HTSS) occur not in the steep eastern shelf but in the gentle western shelf. In line with such presence/absence of the HTSS are the results from some coastal seismic profiles obtained in the present study. The profiles indicate that sand deposits are restricted within the nearshore in the eastern coast, whereas they are persistently traceable to the offshore HTSS in the western coast. Tide is proven to have a negligible influence on the total duration of surf-zone processes. This study may be useful in predicting the consequences of the beach retreat that takes place worldwide as sea levels rise as a result of global warming.

One carbon metabolism in anaerobic bacteria: Regulation of carbon and electron flow during organic acid production: Progress report, February 1, 1987-February 1, 1988

International Nuclear Information System (INIS)

Zeikus, J.G.; Shen, Gwo-Jenn.

1988-01-01

These studies concern the fundamental biochemical mechanisms that control carbon and electron flow in anaerobic bacteria that conserve energy when coupling hydrogen consumption to the production of acetic, propionic, or butyric acids. Two acidogens, Propionispira arboris and Butyribacterium methylotrophicum were chosen as model systems to understand the function of oxidoreductases and electron carriers in the regulation of hydrogen metabolism and single carbon metabolism. In P. arboris, H 2 consumption was linked to the inhibition of CO 2 production and an increase in the propionate/acetate rate; whereas, H 2 consumption was linked to a stimulation of CO 2 consumption and an increase in the butyrate/acetate ratio in B. methylotrophicum. We report studies on the enzymes involved in the regulation of singe carbon metabolism, the enzyme activities and pathways responsible for conversion of multicarbon components to acetate and propionate or butyrate, and how low pH inhibits H 2 and acetic acid production in Sarcina ventriculi as a consequence of hydrogenase regulation. 9 refs

Porous carbon-coated ZnO nanoparticles derived from low carbon content formic acid-based Zn(II) metal-organic frameworks towards long cycle lithium-ion anode material

International Nuclear Information System (INIS)

Gao, Song; Fan, Ruiqing; Li, Bingjiang; Qiang, Liangsheng; Yang, Yulin

2016-01-01

Graphical abstract: The nanocomposites constructed from Zn-based MOFs exhibit low carbon content with super-high rate capability and long cycling life. - Highlights: • Novel ZnO@porous carbon matrix nanocomposites are constructed by pyrolysis of Zn-based MOFs. • The nanocomposites constructed with Zn-based MOFs show low carbon content. • The constructed nanocomposites exhibit high energy density, super-high rate capability and long cycling life. - Abstract: Single-C formic acid-based metal-organic frameworks (MOFs) are used to construct novel ZnO@porous carbon matrix nanocomposites by controlled pyrolysis. In the constructed nanocomposites, the porous carbon matrices act as a confined support to prevent agglomeration of the ZnO nanoparticles and create a rapid electron conductive network. Meanwhile, the well-defined, continuous porous structured MOFs provide a large specific surface area, which increases the contact of electrolyte-electrode and improves the penetration of electrolyte. Especially, the reasonable choice of formic acid-based MOFs construct the low carbon content composite, which contribute to the high energy density and long cycle life. The constructed nanocomposites show stable, ultrahigh rate lithium ion storage properties of 650 mAh g −1 at charge/discharge rate of 1 C even after 200 cycles.

Synthesis of fluorescent carbon dots via microwave carbonization of citric acid in presence of tetraoctylammonium ion, and their application to cellular bioimaging

International Nuclear Information System (INIS)

Bhaisare, Mukesh Lavkush; Talib, Abou; Khan, M. Shahnawaz; Pandey, Sunil; Wu, Hui-Fen

2015-01-01

A jelly-like form of carbon dots (C-dots) was prepared by microwave-assisted synthesis from citric acid in the presence of tetraoctylammonium bromide. The effect of the concentration of tetraoctylammonium bromide was examined. The synthesized carbon dots were characterized by UV–vis, XRD, FTIR, fluorescence and HR-TEM. Fluorescence extends from 350 to 600 nm, and the corresponding excitation wavelengths range from 300 to 460 nm. Quantum yields are at around 0.11. A cytotoxicity study showed carbon dots to be cell permeable and biocompatible which renders them appropriate for imaging applications. The dots were used to image HeLa cell lines via the blue fluorescence of the dots. (author)

Pathology informatics fellowship retreats: The use of interactive scenarios and case studies as pathology informatics teaching tools.

Science.gov (United States)

Lee, Roy E; McClintock, David S; Balis, Ulysses J; Baron, Jason M; Becich, Michael J; Beckwith, Bruce A; Brodsky, Victor B; Carter, Alexis B; Dighe, Anand S; Haghighi, Mehrvash; Hipp, Jason D; Henricks, Walter H; Kim, Jiyeon Y; Klepseis, Veronica E; Kuo, Frank C; Lane, William J; Levy, Bruce P; Onozato, Maristela L; Park, Seung L; Sinard, John H; Tuthill, Mark J; Gilbertson, John R

2012-01-01

Last year, our pathology informatics fellowship added informatics-based interactive case studies to its existing educational platform of operational and research rotations, clinical conferences, a common core curriculum with an accompanying didactic course, and national meetings. The structure of the informatics case studies was based on the traditional business school case study format. Three different formats were used, varying in length from short, 15-minute scenarios to more formal multiple hour-long case studies. Case studies were presented over the course of three retreats (Fall 2011, Winter 2012, and Spring 2012) and involved both local and visiting faculty and fellows. Both faculty and fellows found the case studies and the retreats educational, valuable, and enjoyable. From this positive feedback, we plan to incorporate the retreats in future academic years as an educational component of our fellowship program. Interactive case studies appear to be valuable in teaching several aspects of pathology informatics that are difficult to teach in more traditional venues (rotations and didactic class sessions). Case studies have become an important component of our fellowship's educational platform.

The profile and treatment outcomes of sputum smear positive pulmonary tuberculosis re-treatment cases, in a district medical college of West Bengal, India

Directory of Open Access Journals (Sweden)

Abinash Agarwala

2014-01-01

Full Text Available Background: In a high tuberculosis (TB burden county like India with different regional demography, knowledge about patient profile has a pivotal role in determining and identifying the factors associated with poor treatment outcomes among TB re-treatment cases. Aim: The aim was to describe the demography and clinical characteristics of TB re-treatment cases and to evaluate the factors associated with poor treatment outcomes among those patients. Settings and Design: A prospective longitudinal cohort study was carried out at chest medicine outdoor from February, 2011 to 2014 in a district medical college of West Bengal, India. Materials and Methods: Sputum smear positive re-treatment pulmonary TB patients attending our chest medicine outdoor during the 3 years study period were evaluated for demographic and clinical characteristics on the basis of previous treatment history and records at the beginning of the study. Patients were followed-up during the 8 months treatment period (Category II treatment regimen under Revised National TB Control Program. At the end of the study period, treatment outcomes were analyzed and factors associated with poor treatment outcomes were identified. Statistical Analysis: All variables were described by proportions, and differences between independent groups were compared using the Chi-square test and Fisher′s exact test, as applicable. Results: Among 74 patients, re-treatment was successful in 75.7% of relapse case, 66.7% of loss to follow-up cases and 53.8% of failure cases. Re-treatment failure was higher (38.5% in treatment failure cases compare to relapse cases (10.8% and initial loss to follow-up cases (16.7%. Young age, male, unmarried, employed who work outside appears to be the risk factors for loss to follow-up. Low body mass index, treatment from the private sector, history of alcoholism, radiological cavitory lesion, larger duration of previous treatment, lesser gap from previous treatment has

End of the Little Ice Age in the Alps forced by industrial black carbon

OpenAIRE

Painter, Thomas H.; Flanner, Mark G.; Kaser, Georg; Marzeion, Ben; VanCuren, Richard A.; Abdalati, Waleed

2013-01-01

The end of the Little Ice Age in the European Alps has long been a paradox to glaciology and climatology. Glaciers in the Alps began to retreat abruptly in the mid-19th century, but reconstructions of temperature and precipitation indicate that glaciers should have instead advanced into the 20th century. We observe that industrial black carbon in snow began to increase markedly in the mid-19th century and show with simulations that the associated increases in absorbed sunlight by black carbon...

Sodium phthalamates as corrosion inhibitors for carbon steel in aqueous hydrochloric acid solution

International Nuclear Information System (INIS)

Flores, Eugenio A.; Olivares, Octavio; Likhanova, Natalya V.; Dominguez-Aguilar, Marco A.; Nava, Noel; Guzman-Lucero, Diego; Corrales, Monica

2011-01-01

Highlights: → N-Alkyl-sodium phthalamates as corrosion inhibitors for industry in acidic medium. → Compounds behaved as mixed type inhibitors and followed Langmuir adsorption isotherm. → Efficiencies were proportional to aliphatic chain length and inhibitor concentration. → Iron complexes and chelates with phthalamates contributed to carbon steel protection. - Abstract: Three compounds of N-alkyl-sodium phthalamates were synthesized and tested as corrosion inhibitors for carbon steel in 0.5 M aqueous hydrochloric acid. Tests showed that inhibitor efficiencies were related to aliphatic chain length and dependent on concentration. N-1-n-tetradecyl-sodium phthalamate displayed moderate efficiency against uniform corrosion, 42-86% at 25 deg. C and 25-60% at 40 o C. Tests indicated that compounds behave as mixed type inhibitors where molecular adsorption on steel followed Langmuir isotherm, whereas thermodynamic suggested that a physisorption process occurred. XPS analysis confirmed film formation on surface, where Fe +2 complexes and Fe +2 chelates with phthalamates prevented steel from further corrosion.

Removal of cyanobacterial amino acids in water treatment by activated carbon adsorption

Czech Academy of Sciences Publication Activity Database

Čermáková, Lenka; Kopecká, Ivana; Pivokonský, Martin; Pivokonská, Lenka; Janda, V.

2017-01-01

Roč. 173, č. 1 (2017), s. 330-338 ISSN 1383-5866 Institutional support: RVO:67985874 Keywords : amino acids * activated carbon * adsorption * algal organic matter * water treatment * coagulation * microcystis aeruginosa * peptides/proteins * permanganate pre-oxidation * water treatment Subject RIV: DJ - Water Pollution ; Quality OBOR OECD: Environmental sciences (social aspects to be 5.7) Impact factor: 3.359, year: 2016

Feasibility study of various sulphonation methods for transforming carbon nanotubes into catalysts for the esterification of palm fatty acid distillate

International Nuclear Information System (INIS)

Shuit, Siew Hoong; Tan, Soon Huat

2014-01-01

Highlights: • First report on the production of biodiesel from low-value industrial by-product using sulphonated MWCNTs as catalyst. • Various sulphonation methods were used to transform MWCNTs into catalysts. • SO 3 H were successfully grafted on the surface of MWCNTs, which resulted in a high biodiesel yield and reuse capacity. • The maximum FAME yield by sulphonated MWCNTs was higher than for other popular solid acid catalysts. - Abstract: Sulphonated multi-walled carbon nanotubes were synthesised and utilised as catalysts to transform palm fatty acid distillate, the low-value by-product of palm oil refineries, into the more valuable product of biodiesel. The most common method to prepare carbon-based solid acid catalysts is thermal treatment with concentrated sulphuric acid, which is a time-consuming and energy-intensive process. Therefore, the feasibility of other sulphonation methods, such as the in situ polymerisation of acetic anhydride and sulphuric acid, the thermal decomposition of ammonium sulphate and the in situ polymerisation of poly(sodium4-styrenesulphonate), were examined in this study. The esterification reaction was performed at 170 °C for 3 h at a methanol to palm fatty acid distillate ratio of 20 and catalyst loading of 2 wt% in a pressurised reactor. The fatty acid methyl esters yields achieved by the sulphonated multi-walled carbon nanotubes prepared via thermal treatment with concentrated sulphuric acid, the in situ polymerisation of acetic anhydride and sulphuric acid, the thermal decomposition of ammonium sulphate and the in situ polymerisation of poly(sodium4-styrenesulphonate) were 78.1%, 85.8%, 88.0% and 93.4%, respectively. All catalysts could maintain a high catalytic activity even during the fifth cycle. Among the sulphonation methods, the in situ polymerisation of poly(sodium4-styrenesulphonate) produced the catalyst with the highest acid group density. In addition, the resonance structures of the benzenesulphonic acid

The role of bank collapse on tidal creek ontogeny: A novel process-based model for bank retreat

Science.gov (United States)

Gong, Zheng; Zhao, Kun; Zhang, Changkuan; Dai, Weiqi; Coco, Giovanni; Zhou, Zeng

2018-06-01

Bank retreat in coastal tidal flats plays a primary role on the planimetric shape of tidal creeks and is commonly driven by both flow-induced bank erosion and gravity-induced bank collapse. However, existing modelling studies largely focus on bank erosion and overlook bank collapse. We build a bank retreat model coupling hydrodynamics, bank erosion and bank collapse. To simulate the process of bank collapse, a stress-deformation model is utilized to calculate the stress variation of bank soil after bank erosion, and the Mohr-Coulomb failure criterion is then applied to evaluate the stability of the tidal creek bank. Results show that the bank failure process can be categorized into three stages, i.e., shear failure at the bank toe (stage I), tensile failure on the bank top (stage II), and sectional cracking from the bank top to the toe (stage III). With only bank erosion, the planimetric shapes of tidal creeks are funneled due to the gradually seaward increasing discharge. In contrast to bank erosion, bank collapse is discontinuous, and the contribution of bank collapse to bank retreat can reach 85%, highlighting that the expansion of tidal creeks can be dominated by bank collapse process. The planimetric shapes of tidal creeks are funneled with a much faster expansion rate when bank collapse is considered. Overall, this study makes a further step toward more physical and realistic simulation of bank retreat in estuarine and coastal settings and the developed bank collapse module can be readily included in other morphodynamic models.

Effect of acid treated carbon nanotubes on mechanical, rheological and thermal properties of polystyrene nanocomposites

KAUST Repository

Amr, Issam Thaher; Al-Amer, Adnan M J; Selvin, Thomas P.; Al-Harthi, Mamdouh Ahmed; Girei, Salihu Adamu; Sougrat, Rachid; Atieh, Muataz Ali

2011-01-01

In this work, multiwall carbon nanotubes (CNT) were functionalized by acid treatment and characterized using Fourier Transform Infrared Spectroscopy (FTIR) and thermogravimetric analysis (TGA). Polystyrene/CNT composites of both the untreated

Preparation and Adsorption Performances of Phragmites australis Activated Carbon with High Acidity

Directory of Open Access Journals (Sweden)

FU Cheng-kai

2017-03-01

Full Text Available For removal of heavy metals from wastewater and recycling the wetland plants, the present study investigated the viability of using silage of Phragmites australis (PA to prepare activated carbons (ACs with high acidity. BET surface area, porous texture and surface functional characteristics of ACs were analyzed by N2 adsorption/desorption, elemental analysis and Boehm titration method. ACs presented well-developed micro-porosity and favorable surface acidity. The sorption equilibrium data for Ni (Ⅱ and Cd (Ⅱ sorption onto ACs were analyzed by the Langmuir and Freundlich models. The Langmuir model was fitted well to the adsorption behavior. The properties of high surface acidity promoted the adsorption of heavy metals by the silage-treated ACs and the chemical sorption played the key role in the sorption process.

The Comparative Efficacy of Different Files in The Removal of Different Sealers in Simulated Root Canal Retreatment- An In-vitro Study.

Science.gov (United States)

Kanaparthy, Aruna; Kanaparthy, Rosaiah

2016-05-01

Root canal treatment enjoys a high success rate all over the world and has saved billions of teeth from extraction. However, there are instances of failure, the main causes being insufficient cleaning and inadequate obturation. In such cases the most conservative treatment option would be non-surgical retreatment. It requires regaining access to the entire root canal system through removal of the original root canal filling thus permitting further cleaning and re- obturation. Removal of gutta-percha and sealer becomes a critical step to gain access to the root canal system, remove necrotic tissue debris, bacteria and infected dentin. To compare and evaluate the efficacy of manual hand Hedstrom files and two rotary retreatment file systems ProTaper Universal retreatment files and Mtwo(R) (retreatment) files in the removal of root canal filling material during root canal retreatment and the influence of the type of sealers zinc oxide eugenol and AH plus on the presence of remaining debris in the reinstrumented canals in the apical, middle and coronal third. Sixty single rooted human premolar teeth were divided into 3 Groups of 20 teeth each Group I (20 Teeth): prepared using hand K Files, Group II (20 Teeth): prepared using ProTaper rotary system and Group III (20 Teeth): prepared using Mtwo rotary system. In Groups- IA, IIA, IIIA: (10 teeth each) Obturation was done using Zinc Oxide Eugenol sealer and gutta percha. In Groups- IB, IIB, IIIB: (10 teeth each) obturation was done with AH Plus sealer and gutta percha. All the teeth were subjected to retreatment. Groups IA and IB with Hedstrom files, Groups IIA and IIB with ProTaper retreatment files and for Groups IIIA and IIIB with Mtwo retreatment Files. The roots were longitudinally split and were observed under a stereomicroscope for remaining amount of filling material on the canal walls. Statistical analysis was done using One-way ANOVA (Analysis of variance) test and Tukey HSD Test. Mtwo(R) files showed

Reconstruction of prehistoric pottery use from fatty acid carbon isotope signatures using Bayesian inference

Czech Academy of Sciences Publication Activity Database

Fernandes, R.; Eley, Y.; Brabec, Marek; Lucquin, A.; Millard, A.; Craig, O.E.

2018-01-01

Roč. 117, March (2018), s. 31-42 ISSN 0146-6380 Institutional support: RVO:67985807 Keywords : Fatty acids * carbon isotopes * pottery use * Bayesian mixing models * FRUITS Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 3.081, year: 2016

Preparation of Activated Carbon from Maize Stems by Sulfuric Acids Activation and Their Application in Copper (II Ion Sorption

Directory of Open Access Journals (Sweden)

Erin Ryantin Gunawan

2010-04-01

Full Text Available Activated carbons were prepared from maize (Zea mays L. stems by sulfuric acids activation or chemical methods. The dry maize stems are usually used as low-value energy resources in many countries, burned in the field, or discarded, which are unfavorable to environment. This motivates the investigation of producing value-added products from the dry maize stems, such as activated carbons, as well as solving some environmental problems. The preparation process consisted of sulfuric acid impregnation at different impregnation ratio followed by carbonization at 250-400 oC for 1-4 h. The results show that the impregnation ratio was 1.25, the optimum activation temperature was 300 oC and the activation time was 1 h. The sorption capacity of the activated carbon was 25.1 mg/g.

Starch saccharification by carbon-based solid acid catalyst

Science.gov (United States)

Yamaguchi, Daizo; Hara, Michikazu

2010-06-01

The hydrolysis of cornstarch using a highly active solid acid catalyst, a carbon material bearing SO 3H, COOH and OH groups, was investigated at 353-393 K through an analysis of variance (ANOVA) and an artificial neural network (ANN). ANOVA revealed that reaction temperature and time are significant parameters for the catalytic hydrolysis of starch. The ANN model indicated that the reaction efficiency reaches a maximum at an optimal condition (water, 0.8-1.0 mL; starch, 0.3-0.4 g; catalyst, 0.3 g; reaction temperature, 373 K; reaction time, 3 h). The relationship between the reaction and these parameters is discussed on the basis of the reaction mechanism.

Knickpoint formation and retreat: stairway to heaven or pathway to declivity

Science.gov (United States)

Rengers, Francis; Tucker, Gregory

2016-04-01

The importance of knickpoints in shaping fluvial systems has been observed in laboratory settings, small experimental plots, and at the landscape scale. By creating a step in a river's longitudinal profile, knickpoints can shield upstream tributaries from a much lower base level, and therefore represent a buffer in the energy transfer of a stream system. Knickpoints are located at a transition point between the potential energy of material stored upstream and the kinetic energy of erosion processes and sediment transport below the knickpoint. We hypothesize that the long-term persistence of a discrete, retreating knickpoint requires a balance between the fluvial erosion of the feature, and sedimentation rates downstream. Here we present the results of a short-term (four year) study of knickpoint morphology in a natural gully system to better constrain the conditions necessary to preserve distinct knickpoints over time. We monitored knickpoint erosion using time-lapse photography, repeat terrestrial lidar, soil moisture monitoring, and rainfall-runoff measurements. Our results indicate that shallow subsurface hydrology leads to knickpoint erosion via mass failure, and produces a stable and predictable morphological signature of knickpoint erosion (amphitheater shaped heads). We generalized these observations into a numerical model of erosion/sedimentation to understand the geomorphic legacy of knickpoints in deeply incised gullies. Modeling showed that knickpoints can maintain an incisional step for hundreds to thousands of years when knickpoints retreat via mass failure and sediment is removed from the knickpoint base by fluvial scour. To test simulations of long-term stability generated by the numerical model, we used Optically Stimulated Luminesence to date alluvial deposits at existing gully knickpoints. This geochronological dating confirmed that gully knickpoints have been active in our study area for hundreds to thousands of years, particularly during drought

Carbon dioxide utilization via carbonate-promoted C-H carboxylation.

Science.gov (United States)

Banerjee, Aanindeeta; Dick, Graham R; Yoshino, Tatsuhiko; Kanan, Matthew W

2016-03-10

Using carbon dioxide (CO2) as a feedstock for commodity synthesis is an attractive means of reducing greenhouse gas emissions and a possible stepping-stone towards renewable synthetic fuels. A major impediment to synthesizing compounds from CO2 is the difficulty of forming carbon-carbon (C-C) bonds efficiently: although CO2 reacts readily with carbon-centred nucleophiles, generating these intermediates requires high-energy reagents (such as highly reducing metals or strong organic bases), carbon-heteroatom bonds or relatively acidic carbon-hydrogen (C-H) bonds. These requirements negate the environmental benefit of using CO2 as a substrate and limit the chemistry to low-volume targets. Here we show that intermediate-temperature (200 to 350 degrees Celsius) molten salts containing caesium or potassium cations enable carbonate ions (CO3(2-)) to deprotonate very weakly acidic C-H bonds (pKa > 40), generating carbon-centred nucleophiles that react with CO2 to form carboxylates. To illustrate a potential application, we use C-H carboxylation followed by protonation to convert 2-furoic acid into furan-2,5-dicarboxylic acid (FDCA)--a highly desirable bio-based feedstock with numerous applications, including the synthesis of polyethylene furandicarboxylate (PEF), which is a potential large-scale substitute for petroleum-derived polyethylene terephthalate (PET). Since 2-furoic acid can readily be made from lignocellulose, CO3(2-)-promoted C-H carboxylation thus reveals a way to transform inedible biomass and CO2 into a valuable feedstock chemical. Our results provide a new strategy for using CO2 in the synthesis of multi-carbon compounds.

[Test your decision-making. When to do endodontic retreatment? Results of a study].

Science.gov (United States)

Aryanpour, S; D'Hoore, W; Van Nieuwenhuysen, J P

2000-01-01

The goals of this survey were to determine the most frequent therapeutic option and to evaluate the consensus among a sample of Belgian practitioners managing the same simulated cases of root treated teeth. On average, conservative options (nonsurgical retreatment 35.27% and no retreatment 29.61%) are the most selected alternatives. Surgical options and extraction respectively constitute 21.18% and 13% of the treatment propositions. As expected, the presence of radiographic and/or clinical signs resulted in a more aggressive attitude, but the presence of symptoms does not seem to be a valid reason for reintervention. The results of the study demonstrate considerable interindividual variations in clinical management of root treated teeth, regardless of personal factors, such as gender, years of experience and graduation institution. Even if a consensus appears within a group of professionals, it is not necessarily applied by a majority of practitioners; this contributes certainly to the explanation of the geographical or institutional variations noted in the medical practices.

Highly active carbon supported Pd cathode catalysts for direct formic acid fuel cells

Science.gov (United States)

Mikolajczuk-Zychora, A.; Borodzinski, A.; Kedzierzawski, P.; Mierzwa, B.; Mazurkiewicz-Pawlicka, M.; Stobinski, L.; Ciecierska, E.; Zimoch, A.; Opałło, M.

2016-12-01

One of the drawbacks of low-temperature fuel cells is high price of platinum-based catalysts used for the electroreduction of oxygen at the cathode of the fuel cell. The aim of this work is to develop the palladium catalyst that will replace commonly used platinum cathode catalysts. A series of palladium catalysts for oxygen reduction reaction (ORR) were prepared and tested on the cathode of Direct Formic Acid Fuel Cell (DFAFC). Palladium nanoparticles were deposited on the carbon black (Vulcan) and on multiwall carbon nanotubes (MWCNTs) surface by reduction of palladium(II) acetate dissolved in ethanol. Hydrazine was used as a reducing agent. The effect of functionalization of the carbon supports on the catalysts physicochemical properties and the ORR catalytic activity on the cathode of DFAFC was studied. The supports were functionalized by treatment in nitric acid for 4 h at 80 °C. The structure of the prepared catalysts has been characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), transmission electron microscope (TEM) and cyclic voltammetry (CV). Hydrophilicity of the catalytic layers was determined by measuring contact angles of water droplets. The performance of the prepared catalysts has been compared with that of the commercial 20 wt.% Pt/C (Premetek) catalyst. The maximum power density obtained for the best palladium catalyst, deposited on the surface of functionalized carbon black, is the same as that for the commercial Pt/C (Premetek). Palladium is cheaper than platinum, therefore the developed cathode catalyst is promising for future applications.

Diameter sensitive effect in singlewalled carbon nanotubes upon acid treatment

International Nuclear Information System (INIS)

Costa, S.; Borowiak-Palen, E.

2009-01-01

Singlewalled carbon nanotubes (SWCNT) exhibit very unique properties. As an electronic system they undergo amphoteric doping effects (n-type and p-type) which can be reversed. These processes affect the optical and vibronic properties of the carbon nanotubes. The most common and widely used procedure which changes the properties of the SWCNT is acid treatment applied as a purification procedure. This effect has been widely studied but not fully understood so far. Here, we present a study, in which a diameter sensitive effect has been observed. Therefore, two kinds of SWCNT samples have been studied: (i) produced via chemical vapour deposition with a broad diameter distribution, and (ii) synthesised by the laser ablation technique which is commonly known to result in narrow diameter distribution bulk SWCNT samples. Resonance Raman spectroscopy, optical absorption spectroscopy, and Fourier transform middle-infrared spectroscopy have been applied for the characterisation of the samples.

Characteristics of polyaniline electrosynthesized in propylene carbonate medium in the presence of di- and trichloroacetic acids

Directory of Open Access Journals (Sweden)

Venancio Everaldo C.

2001-01-01

Full Text Available In the present work the characterization of polyaniline electrosynthesized in propylene carbonate medium in the presence of di- and trichloroacetic acids was performed using different techniques. The electrochemical response by cyclic voltammetry showed redox processes due to the formation of polaron and bipolaron and polymer degradation. The characterization by infrared and UV-visible spectroscopies indicated that the polymers are in the emeraldine salt form with perchlorate anions incorporated. The films produced with both acids in propylene carbonate media presented a compact morphology as observed by scanning electron microscopy. By testing the polyaniline film produced in selected conditions in a lithium battery environment it was found that it presents a high coulombic efficiency, promising for battery applications.

Comparative evaluation of cyclic fatigue resistance of D-RaCe and ProTaper retreatment instruments in curved artificial canals.

Science.gov (United States)

Topçuoğlu, H S; Topçuoğlu, G; Aktı, A

2016-06-01

To compare the cyclic fatigue resistance of D-RaCe and ProTaper rotary nickel-titanium (NiTi) retreatment files when used in curved artificial canals. A total of 120 new D-RaCe DR2 and ProTaper D3 retreatment files were tested in stainless steel artificial canals having 45° and 60° angles of curvature. Thirty instruments of each of the file systems were tested in both angles of curvature (n = 30). The retreatment instruments were rotated until fracture to calculate the number of cycles to failure. The length of each fractured fragment was recorded. Data were analysed by independent sample t-test. Fractured surfaces of the instruments were analysed by scanning electron microscopy. In the canal with 45° angle of curvature, no significant difference was observed between the retreatment systems (P > 0.05); on the other hand, in the canal with 60° angle of curvature, D-RaCe DR2 instruments had greater cyclic fatigue resistance than ProTaper D3 (P  0.05). The fracture surfaces of the instruments had morphologic characteristics of ductile fracture. D-RaCe DR2 instrument exhibited greater cyclic fatigue resistance than ProTaper D3 only in root canals with 60° angle of curvature. © 2015 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Efficacy of Twisted File Adaptive, Reciproc and ProTaper Universal Retreatment instruments for root-canal-filling removal: A cone-beam computed tomography study.

Science.gov (United States)

Akbulut, Makbule Bilge; Akman, Melek; Terlemez, Arslan; Magat, Guldane; Sener, Sevgi; Shetty, Heeresh

2016-01-01

The aim of this study was to evaluate the efficacy of Twisted File (TF) Adaptive, Reciproc, and ProTaper Universal Retreatment (UR) System instruments for removing root-canal-filling. Sixty single rooted teeth were decoronated, instrumented and obturated. Preoperative CBCT scans were taken and the teeth were retreated with TF Adaptive, Reciproc, ProTaper UR, or hand files (n=15). Then, the teeth were rescanned, and the percentage volume of the residual root-canal-filling material was established. The total time for retreatment was recorded, and the data was statistically analyzed. The statistical ranking of the residual filling material volume was as follows: hand file=TF Adaptive>ProTaper UR=Reciproc. The ProTaper UR and Reciproc systems required shorter periods of time for retreatment. Root canal filling was more efficiently removed by using Reciproc and ProTaper UR instruments than TF Adaptive instruments and hand files. The TF Adaptive system was advantageous over hand files with regard to operating time.

Organic Acids: The Pools of Fixed Carbon Involved in Redox Regulation and Energy Balance in Higher Plants

Directory of Open Access Journals (Sweden)

Abir U Igamberdiev

2016-07-01

Full Text Available Organic acids are synthesized in plants as a result of the incomplete oxidation of photosynthetic products and represent the stored pools of fixed carbon accumulated due to different transient times of conversion of carbon compounds in metabolic pathways. When redox level in the cell increases, e.g., in conditions of active photosynthesis, the tricarboxylic acid (TCA cycle in mitochondria is transformed to a partial cycle supplying citrate for the synthesis of 2-oxoglutarate and glutamate (citrate valve, while malate is accumulated and participates in the redox balance in different cell compartments (via malate valve. This results in malate and citrate frequently being the most accumulated acids in plants. However, the intensity of reactions linked to the conversion of these compounds can cause preferential accumulation of other organic acids, e.g., fumarate or isocitrate, in higher concentrations than malate and citrate. The secondary reactions, associated with the central metabolic pathways, in particularly with the TCA cycle, result in accumulation of other organic acids that are derived from the intermediates of the cycle. They form the additional pools of fixed carbon and stabilize the TCA cycle. Trans-aconitate is formed from citrate or cis-aconitate, accumulation of hydroxycitrate can be linked to metabolism of 2-oxoglutarate, while 4-hydroxy-2-oxoglutarate can be formed from pyruvate and glyoxylate. Glyoxylate, a product of either glycolate oxidase or isocitrate lyase, can be converted to oxalate. Malonate is accumulated at high concentrations in legume plants. Organic acids play a role in plants in providing redox equilibrium, supporting ionic gradients on membranes, and acidification of the extracellular medium.

Competitive effects of humic acid and wastewater on adsorption of Methylene Blue dye by activated carbon and non-imprinted polymers.

Science.gov (United States)

Murray, Audrey; Örmeci, Banu

2018-04-01

Natural organic matter (NOM), present in natural waters and wastewater, decreases adsorption of micropollutants, increasing treatment costs. This research investigated mechanisms of competition for non-imprinted polymers (NIPs) and activated carbon with humic acid and wastewater. Three different types of activated carbons (Norit PAC 200, Darco KB-M, and Darco S-51) were used for comparison with the NIP. The lower surface area and micropore to mesopore ratio of the NIP led to decreased adsorption capacity in comparison to the activated carbons. In addition, experiments were conducted for single-solute adsorption of Methylene Blue (MB) dye, simultaneous adsorption with humic acid and wastewater, and pre-loading with humic acid and wastewater followed by adsorption of MB dye using NIP and Norit PAC 200. Both the NIP and PAC 200 showed significant decreases of 27% for NIP (p=0.087) and 29% for PAC 200 (p=0.096) during simultaneous exposure to humic acid and MB dye. There was no corresponding decrease for NIP or PAC 200 pre-loaded with humic acid and then exposed to MB. In fact, for PAC 200, the adsorption capacity of the activated carbon increased when it was pre-loaded with humic acid by 39% (p=0.0005). For wastewater, the NIP showed no significant increase or decrease in adsorption capacity during either simultaneous exposure or pre-loading. The adsorption capacity of PAC 200 increased by 40% (p=0.001) for simultaneous exposure to wastewater and MB. Pre-loading with wastewater had no effect on MB adsorption by PAC 200. Copyright © 2017. Published by Elsevier B.V.

Assessing the costs and market impacts of carbon sequestration, climate change, and acid rain

International Nuclear Information System (INIS)

Callaway, J.M.

2000-03-01

This thesis provides fourteen journal articles and papers. Thirteen of these papers were published in referred journals, covering environmental economics, policy modelling, policy analysis, and the physical sciences. One paper was published as a USDA Forest Service research report. The papers in the thesis are divided into three topical areas: 1) Section 2: The Economics of Carbon Sequestration. Eight papers plus Appendix A of the thesis cover the development and application of models to estimate the economic costs and management consequences of policies to sequester carbon emissions by planting trees on agricultural land in the US or through more intensive forest management. 2) Section 3: The Economics of Climate Change Damages. Two papers of the thesis cover the development of models that can be used to estimate the market and nonmarket damages associated with the impacts of climate change on water resources in the US. 3) Section 4: The Economics of Acid Rain Damages. Three papers in the thesis examine the methods that were developed to estimate the damages due to acid rain in the US by the National Acid Precipitation Assessment Program (NAPAP) and discuss more generally the role of economic policy analysis in this assessment. (EHS)

Iodide-Photocatalyzed Reduction of Carbon Dioxide to Formic Acid with Thiols and Hydrogen Sulfide.

Science.gov (United States)

Berton, Mateo; Mello, Rossella; González-Núñez, María Elena

2016-12-20

The photolysis of iodide anions promotes the reaction of carbon dioxide with hydrogen sulfide or thiols to quantitatively yield formic acid and sulfur or disulfides. The reaction proceeds in acetonitrile and aqueous solutions, at atmospheric pressure and room temperature by irradiation using a low-pressure mercury lamp. This transition-metal-free photocatalytic process for CO 2 capture coupled with H 2 S removal may have been relevant as a prebiotic carbon dioxide fixation. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Endodontic retreatment of dens invaginatus presenting with gutta-percha overfilling at the attached gingiva and chronic apical periodontitis: unusual clinical report.

Science.gov (United States)

Robazza, Carlos Roberto Colombo; Alves e Motta, Julio Cesar; de Carli, Marina Lara; de Oliveira Pedreira, Fernanda Rafaelly; Hanemann, Joao Adolfo Costa

2013-05-01

This work describes the retreatment of an unusual case of dens invaginatus with gutta-percha overfilling at the gingival mucosa and chronic apical periodontitis in a 34-year-old woman. Initial periapical radiograph showed the presence of type II dens invaginatus with poor quality obturation, root perforation and chronic apical periodontitis of tooth 22. Dens invaginatus is a tooth malformation caused by infolding of the dental papilla during tooth development. This anomaly has been associated with increased prevalence of pulpal and periapical diseases. Conventional endodontic retreatment was performed using rotary files and calcium hydroxide paste as intracanal dressing. After 7 days, root canal was filled with guttapercha points and Sealapex® sealer. Obturation was radiographically followed and, after 3 years, absence of fistula and periapical radiolucency was observed, thus conventional endodontic therapy proved to be successful. Conventional endodontic retreatment of type II dens invaginatus has been successful for a 3-year period, showing a better treatment alternative. Conservative endodontic retreatment of dens invaginatus should be considered to promote periapical healing with complete reconstitution of bone and periodontal ligament regeneration without signs of recurrence over a period of 3 years. Moreover, it preserves the entire tooth.

Retreatment of Recurrent Cystic Craniopharyngioma With Chromic Phosphorus P 32

Science.gov (United States)

Kumar, P.P.; Good, R.R.; Skultety, F.M.; Jones, E.O.; Chu, W.K.

1986-01-01

A cystic craniopharyngioma in a two-year-old boy recurred six months after surgery and postoperative external-beam radiotherapy. Successful retreatment was accomplished with radioisotope injection of 0.5 mCi of chromic phosphorus P 32 into the intracranial cyst, which delivered approximately 300.00 Gy to the cyst wall. The patient's symptoms were relieved, and he is without evidence of disease or cystic fluid accumulation four years after intracavitary 32P irradiation. ImagesFigure 1Figure 2Figure 3 PMID:3735454

Timing of Glacial Lake Missoula Outburst Floods and the southwestern Cordilleran Ice Sheet retreat.

Science.gov (United States)

Hendy, I. L.; Bervid, H. D.; Carlson, A. E.

2017-12-01

Glacial Lake Missoula formed when the Purcell Trench Lobe dammed the Clark Fork River in Montana and catastrophically collapsed repeatedly through the last glacial period as the southern Cordilleran Ice Sheet advanced and retreated. A well-dated 50-kyr jumbo piston core MD02-2496 (48.97˚ N, 127.04˚ W, water depth of 1243 m) collected from the continental slope 75 km off Vancouver Island contains evidence of these floods. The in-situ bulk elemental composition of the 35-m core was determined at 1 mm intervals using an ITRAX X-ray Fluorescence (XRF) Core Scanner (Cox Analytical Instruments) at the Sediment Geochemistry Lab of the College of Earth, Ocean, and Atmospheric Sciences at Oregon State University. With 40 mixed planktonic foraminifera and bulk organic carbon 14C ages, the core provides a high-resolution resolution record of glaciomarine sedimentation during deglaciation. A series of >81 layers of fine-grained sediments with ancient (K/Ar ages of 300 Ma and eNd of -8) shale-like (high Rb counts) composition can be found between 19.6 and 9.2 m below coretop. These layers are interspersed by coarser grained, young (K/Ar ages of 100 Ma and eNd of -3) sediments containing ice-rafted debris (IRD). The composition and age of the layers indicates the sediments originated in Glacial Lake Missoula and were transported by ocean currents 250 miles north along the west coast of North America. The flood layers begin at 19.5 ka with five thin (5 cm thick) appear after 19.3 ka. At 17.1 ka, IRD concentrations increase from 50 grains g-1 from 16.5-16.35 ka, except in flood layers, as the Juan de Fuca Strait deglaciated. Another 16 flood layers occur from 16.3-15.65 ka; however, the base and top of these layers are diffuse rather than abrupt like earlier flood layers suggesting enhanced mixing between flood and melt waters. The final flood layers from 14.9-14.5 ka are thin (Lake Missoula flood sedimentation changed during the advance and retreat of the Cordilleran Ice Sheet.

Simultaneous detection of ascorbic acid, dopamine, uric acid and tryptophan with Azure A-interlinked multi-walled carbon nanotube/gold nanoparticles composite modified electrode

Directory of Open Access Journals (Sweden)

Hayati Filik

2016-05-01

Full Text Available In this paper, multi-walled carbon nanotube/Azure A/gold nanoparticle composites (Nafion/AuNPs/AzA/MWCNTs were prepared by binding gold nanoparticles to the surfaces of Azure A-coated carbon nanotubes. Nafion/AuNPs/AzA/MWCNTs based electrochemical sensor was fabricated for the simultaneous determination of ascorbic acid, dopamine, uric acid, and tryptophan. Cyclic voltammetry and electrochemical impedance spectroscopy were used to characterize the electrochemical properties of the modified electrodes. The modified electrode showed excellent electrocatalytic activity toward ascorbic acid, dopamine, uric acid, and tryptophan (pH 7.0. The experiment results showed that the linear response range for simultaneous detection of AA, DA, UA and Trp were 300–10,000 μM, 0.5–50 μM, 0.5–50 μM and 1.0–100 μM, respectively, and the detection limits were 16 μM, 0.014 μM, 0.028 μM and 0.56 μM (S/N = 3. The proposed method offers promise for simple, rapid, selective and cost-effective analysis of small biomolecules. The procedure was also applied to the determination of tryptophan in spiked milk samples.

An in situ generated carbon as integrated conductive additive for hierarchical negative plate of lead-acid battery

Science.gov (United States)

Saravanan, M.; Ganesan, M.; Ambalavanan, S.

2014-04-01

In this work, we report an in situ generated carbon from sugar as additive in the Negative Active Mass (NAM) which enhances the charge-discharge characteristics of the lead-acid cells. In situ formed sugar derived carbon (SDC) with leady oxide (LO) provides a conductive network and excellent protection against NAM irreversible lead sulfation. The effect of SDC and carbon black (CB) added negative plates are characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), galvanostatic charge-discharge, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), respectively. The results show that subtle changes in the addition of carbon to NAM led to subsequent changes on the performance during partial-state-of-charge (PSoC) operations in lead-acid cells. Furthermore, SDC added cells exhibit remarkable improvement in the rate capability, active material utilization, cycle performance and charge acceptance compared to that of the conventional CB added cells. The impact of SDC with LO at various synthesis conditions on the electrochemical performance of the negative plate is studied systematically.

Evaluation of Dentin Defect Formation during Retreatment with Hand and Rotary Instruments: A Micro-CT Study.

Science.gov (United States)

Yilmaz, Ayca; Helvacioglu-Yigit, Dilek; Gur, Cansu; Ersev, Handan; Kiziltas Sendur, Gullu; Avcu, Egemen; Baydemir, Canan; Abbott, Paul Vincent

2017-01-01

The purpose of this study was to compare the incidence and longitudinal propagation of dentin defects after gutta-percha removal with hand and rotary instruments using microcomputed tomography. Twenty mandibular incisors were prepared using the balanced-force technique and scanned in a 19.9  μ m resolution. Following filling with the lateral compaction technique, gutta-percha was removed with ProTaper Universal Retreatment (PTUR) or hand instruments. After rescanning, a total of 24,120 cross-sectional images were analyzed. The numbers, types, and longitudinal length changes of defects were recorded. Defects were observed in 36.90% of the cross sections. A total of 73 defects were comprised of 87.67% craze lines, 2.73% partial cracks, and 9.58% fractures. No significant difference in terms of new defect formation was detected between the retreatment groups. The apical and middle portions of the roots had more dentin defects than the coronal portions. Defects in three roots of the PTUR instrument group increased in length. Under the conditions of this in vitro study, gutta-percha removal seemed to not increase the incidence of dentin defect formation, but the longitudinal defect propagation finding suggests possible cumulative dentinal damage due to additional endodontic procedures. Hand and rotary instrumentation techniques caused similar dentin defect formation during root canal retreatment.

Where to “Rock”? Choice of retreat sites by a gecko in a semi-arid habitat

Directory of Open Access Journals (Sweden)

Andreia Penado

2015-06-01

Full Text Available The Selvagens gecko (Tarentola boettgeri bischoffi Joger, 1984 is a medium sized gecko endemic to the Selvagens archipelago, Madeira, Portugal. The biology of this gecko is poorly known and in this study we present the first evidence regarding its habitat use. In 2010 (spring and autumn and 2011 (spring, we collected data on the characteristics of the habitat surrounding 168 rocks used by these geckos as retreat sites, as well as on 75 randomly selected rocks. We also recorded body measurements of the individuals caught under each rock. In both seasons retreat site occupancy was found to be related to rock area, with geckos being found mainly under large rocks. Interestingly, we found that in spring heavier males, in better body condition, occupied the largest rocks and larger geckos occupied rocks closer to creek beds. Our results shed some light upon the behavioural ecology of this nocturnally active ectotherm, that spends the day under a retreat site: i intraspecific competition may be an ecological factor prevalent in this species, since larger individuals occupy larger rocks, located in a presumably high quality micro-habitat; ii the possibility of spring territoriality in males, that compete for good quality shelters.

Elucidating adsorption mechanisms of phthalate esters upon carbon nanotubes/graphene and natural organic acid competitive effects in water by DFT and MD calculations

Energy Technology Data Exchange (ETDEWEB)

Wang, Zhuang; Wang, Se; Chen, Min Dong; Xu, Defu [Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Jiangsu KeyLaboratory of Atmospheric Environment Monitoring and Pollution Control (AEMPC), School ofEnvironmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing (China); Tang, Lili [Jiangsu Environmental Monitoring Centre, Nanjing (China); Wang, Degao [Dept. of Environmental Science and Engineering, Dalian Maritime University, Dalian (China)

2015-06-15

Simulations at multiple levels were performed to investigate the aqueous adsorption of phthalate esters (PAEs) on carbon nanoparticles and to find the competitive effect of a low molecular weight natural organic acid (benzoic acid) on the adsorption process. Six PAEs of varying alkyl side chain lengths and three carbon-based nanomaterials including a single-walled carbon nanotube (SWNT), double-walled carbon nanotube (DWNT), and graphene (G) were studied. Results showed that the adsorption energies calculated using density functional theory increase with increasing length of the PAE alkyl chain. G exhibits higher adsorption capacity for the PAEs than SWNT and DWNT. The absolute adsorption energies of these systems also display a positive linear correlation with the hydrophobicity of the PAE molecules. Molecular dynamics simulations indicate that the presence of neutral/anionic benzoic acid in water alleviates the PAE adsorption. Furthermore, anionic benzoic acid exerts more impact on the PAE adsorption than the neutral form.

Supported zirconium sulfate on carbon nanotubes as water-tolerant solid acid catalyst

International Nuclear Information System (INIS)

Juan, Joon Ching; Jiang Yajie; Meng Xiujuan; Cao Weiliang; Yarmo, Mohd Ambar; Zhang Jingchang

2007-01-01

A new solid acid of zirconium sulfate (CZ) was successfully supported on carbon nanotube (CNT) for esterification reaction. Preparation conditions of the supported CZ have been investigated, to obtain highest catalytic activity for esterification reaction. XRD, TEM, BET, X-ray photoelectron spectra (XPS) and in situ FTIR analysis has also been carried out to understand the characteristics of the catalyst. In the esterification of acrylic acid with n-octanol, the supported CZ exhibited high catalytic activity and stability. The catalytic activity was nearly unchanged during four times of reuse. XRD and TEM analysis indicated that CZ was finely dispersed on CNT. XPS analysis shows that the CZ species was preserved and the chemical environment of the CZ has changed after loaded on CNT. This finding show that CNT as CZ support is an efficient water-tolerant solid acid

Detection of nitrite based on fluorescent carbon dots by the hydrothermal method with folic acid

Science.gov (United States)

Lin, Haitao; Ding, Liyun; Zhang, Bingyu; Huang, Jun

2018-05-01

A fluorescent carbon dots probe for the detection of aqueous nitrite was fabricated by a one-pot hydrothermal method, and the transmission electron microscope, X-ray diffractometer, UV-Vis absorption spectrometer and fluorescence spectrophotometer were used to study the property of carbon dots. The fluorescent property of carbon dots influenced by the concentration of aqueous nitrite was studied. The interaction between the electron-donating functional groups and the electron-accepting nitrous acid could account for the quenching effect on carbon dots by adding aqueous nitrite. The products of the hydrolysis of aqueous nitrite performed a stronger quenching effect at lower pH. The relationship between the relative fluorescence intensity of carbon dots and the concentration of nitrite was described by the Stern-Volmer equation (I0/I - 1 = 0.046[Q]) with a fine linearity (R2 = 0.99). The carbon dots-based probe provides a convenient method for the detection of nitrite concentration.

The effect of structure and a secondary carbon source on the microbial degradation of chlorophenoxy acids.

Science.gov (United States)

Evangelista, S; Cooper, D G; Yargeau, V

2010-05-01

Pseudomonas putida, Aspergillus niger, Bacillus subtilis, Pseudomonas fluorescens, Sphingomonas herbicidovorans and Rhodococcus rhodochrous growing on glucose in a medium containing one of three chlorophenoxy acids at a concentration of 0.1 g L(-1) (clofibric acid, (R)-2-(4-chloro-2-methylphenoxy)propionic acid (mecoprop or MCPP) and 4-chloro-2-methylphenoxyacetic acid (MCPA)) degraded these compounds to varying degrees; from nonmeasurable to almost complete removal. These results with the addition of glucose (2.5 g L(-1)) as an easy to use carbon source indicated the formation of metabolites different from results reported in the literature for growth studies in which the chlorophenoxy acid was the sole carbon source. The metabolite, 4-chloro-2-methylphenol, which had been reported previously, was only observed in trace amounts for MCPP and MCPA in the presence of S. herbicidovorans and glucose. In addition, three other compounds (M1, M3 and M4) were observed. It is suggested that these unidentified metabolites resulted from ring opening of the metabolite 4-chloro-2-methylphenol (M2). The rate of biodegradation of the chlorophenoxy acids was influenced by the degree of steric hindrance adjacent to the internal oxygen bond common to all three compounds. The most hindered compound, clofibric acid, was converted to ethyl clofibrate by R. rhodochrous but was not degraded by any microorganisms studied. The more accessible internal oxygen bonds of the other two chlorophenoxy acids, MCPP and MCPA, were readily broken by S. herbicidovorans. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Pathology informatics fellowship retreats: The use of interactive scenarios and case studies as pathology informatics teaching tools

Directory of Open Access Journals (Sweden)

Roy E Lee

2012-01-01

Full Text Available Background: Last year, our pathology informatics fellowship added informatics-based interactive case studies to its existing educational platform of operational and research rotations, clinical conferences, a common core curriculum with an accompanying didactic course, and national meetings. Methods: The structure of the informatics case studies was based on the traditional business school case study format. Three different formats were used, varying in length from short, 15-minute scenarios to more formal multiple hour-long case studies. Case studies were presented over the course of three retreats (Fall 2011, Winter 2012, and Spring 2012 and involved both local and visiting faculty and fellows. Results: Both faculty and fellows found the case studies and the retreats educational, valuable, and enjoyable. From this positive feedback, we plan to incorporate the retreats in future academic years as an educational component of our fellowship program. Conclusions: Interactive case studies appear to be valuable in teaching several aspects of pathology informatics that are difficult to teach in more traditional venues (rotations and didactic class sessions. Case studies have become an important component of our fellowship′s educational platform.

Phase behaviour of the ternary mixture system of poly(L-lactic acid), dichloromethane and carbon dioxide

International Nuclear Information System (INIS)

Gwon, Jungmin; Cho, Dong Woo; Kim, Soo Hyeon; Shin, Hun Yong; Kim, Hwayong

2012-01-01

Highlights: ► The high pressure phase behaviour of poly(L-lactic acid), dichloromethane and carbon dioxide ternary mixtures was measured. ► The experimental data shows the characteristics of the LCST behaviour of polymer–solvent–gas systems. ► The experimental data correlation was performed using the hybrid EOS. - Abstract: In this study, the high pressure phase behaviour of poly(L-lactic acid) (M = 312,000), dichloromethane and carbon dioxide ternary mixtures was studied using a variable volume view cell at temperatures ranging from 313.15 K to 363.15 K and pressures of up to 30.0 MPa as functions of temperature and the CO 2 /dichloromethane mass ratio at poly(L-lactic acid) weight fractions of 1.0%, 2.5% and 3.0%. The experimental results were correlated with the hybrid equation of state for the CO 2 -polymer system using the van der Waals one-fluid mixing rule with three adjustable binary interaction parameters.

[Calcium suppletion for patients who use gastric acid inhibitors: calcium citrate or calcium carbonate?].

NARCIS (Netherlands)

Jonge, H.J. de; Gans, R.O.; Huls, G.A.

2012-01-01

Various calcium supplements are available for patients who have an indication for calcium suppletion. American guidelines and UpToDate recommend prescribing calcium citrate to patients who use antacids The rationale for this advice is that water-insoluble calcium carbonate needs acid for adequate

Highly microporous carbons derived from a complex of glutamic acid and zinc chloride for use in supercapacitors

Science.gov (United States)

Dong, Xiao-Ling; Lu, An-Hui; He, Bin; Li, Wen-Cui

2016-09-01

The selection of carbon precursor is an important factor when designing carbon materials. In this study, a complex derived from L-glutamic acid and zinc chloride was used to prepare highly microporous carbons via facile pyrolysis. L-glutamic acid, a new carbon precursor with nitrogen functionality, coordinated with zinc chloride resulted in a homogeneous distribution of Zn2+ on the molecular level. During pyrolysis, the evaporation of the in situ formed zinc species creates an abundance of micropores together with the inert gases. The obtained carbons exhibit high specific surface area (SBET: 1203 m2 g-1) and a rich nitrogen content (4.52 wt%). In excess of 89% of the pore volume consists of micropores with pore size ranging from 0.5 to 1.2 nm. These carbons have been shown to be suitable for use as supercapacitor electrodes, and have been tested in 6 M KOH where a capacitance of 217 F g-1 was achieved at a current density of 0.5 A g-1. A long cycling life of 30 000 cycles was achieved at a current density of 1 A g-1, with only a 9% loss in capacity. The leakage current through a two-electrode device was measured as 2.3 μA per mg of electrode and the self-discharge characteristics were minimal.

Nonsurgical endodontic retreatment of fused teeth with transposition: a case report

Directory of Open Access Journals (Sweden)

Miguel Agostinho Beco Pinto Cardoso

2016-05-01

Full Text Available Tooth transposition is a disorder in which a permanent tooth develops and erupts in the normal position of another permanent tooth. Fusion and gemination are developmental disturbances presenting as the union of teeth. This article reports the nonsurgical retreatment of a very rare case of fused teeth with transposition. A patient was referred for endodontic treatment of her maxillary left first molar in the position of the first premolar, which was adjacent to it on the distobuccal side. Orthopantomography and periapical radiography showed two crowns sharing the same root, with a root canal treatment and an associated periapical lesion. Tooth fusion with transposition of a maxillary molar and a premolar was diagnosed. Nonsurgical endodontic retreatment was performed. At four yr follow-up, the tooth was asymptomatic and the radiolucency around the apical region had decreased, showing the success of our intervention. The diagnosis and treatment of fused teeth require special attention. The canal system should be carefully explored to obtain a full understanding of the anatomy, allowing it to be fully cleaned and obturated. Thermoplastic techniques were useful in obtaining hermetic obturation. A correct anatomical evaluation improves the set of treatment options under consideration, leading to a higher likelihood of esthetically and functionally successful treatment.

Recovery of carboxylic acids produced during dark fermentation of food waste by adsorption on Amberlite IRA-67 and activated carbon.

Science.gov (United States)

Yousuf, Ahasa; Bonk, Fabian; Bastidas-Oyanedel, Juan-Rodrigo; Schmidt, Jens Ejbye

2016-10-01

Amberlite IRA-67 and activated carbon were tested as promising candidates for carboxylic acid recovery by adsorption. Dark fermentation was performed without pH control and without addition of external inoculum at 37°C in batch mode. Lactic, acetic and butyric acids, were obtained, after 7days of fermentation. The maximum acid removal, 74%, from the Amberlite IRA-67 and 63% from activated carbon was obtained from clarified fermentation broth using 200gadsorbent/Lbroth at pH 3.3. The pH has significant effect and pH below the carboxylic acids pKa showed to be beneficial for both the adsorbents. The un-controlled pH fermentation creates acidic environment, aiding in adsorption by eliminating use of chemicals for efficient removal. This study proposes simple and easy valorization of waste to valuable chemicals. Copyright © 2016 Elsevier Ltd. All rights reserved.

Changes in the marine carbonate system of the western Arctic: patterns in a rescued data set

Directory of Open Access Journals (Sweden)

Lisa A. Miller

2014-11-01

Full Text Available A recently recovered and compiled set of inorganic carbon data collected in the Canadian Arctic since the 1970s has revealed substantial change, as well as variability, in the carbonate system of the Beaufort Sea and Canada Basin. Whereas the role of this area as a net atmospheric carbon sink has been confirmed, high pCO2 values in the upper halocline underscore the potential for CO2 outgassing as sea ice retreats and upwelling increases. In addition, increasing total inorganic carbon and decreasing alkalinity are increasing pCO2 and decreasing CaCO3 saturation states, such that undersaturation with respect to aragonite now occurs regularly in both deep waters and the upper halocline.

Predicting the retreat and migration of tidal forests along the northern Gulf of Mexico under sea-level rise

Science.gov (United States)

Doyle, T.W.; Krauss, K.W.; Conner, W.H.; From, A.S.

2010-01-01

Tidal freshwater forests in coastal regions of the southeastern United States are undergoing dieback and retreat from increasing tidal inundation and saltwater intrusion attributed to climate variability and sea-level rise. In many areas, tidal saltwater forests (mangroves) contrastingly are expanding landward in subtropical coastal reaches succeeding freshwater marsh and forest zones. Hydrological characteristics of these low-relief coastal forests in intertidal settings are dictated by the influence of tidal and freshwater forcing. In this paper, we describe the application of the Sea Level Over Proportional Elevation (SLOPE) model to predict coastal forest retreat and migration from projected sea-level rise based on a proxy relationship of saltmarsh/mangrove area and tidal range. The SLOPE model assumes that the sum area of saltmarsh/mangrove habitat along any given coastal reach is determined by the slope of the landform and vertical tide forcing. Model results indicated that saltmarsh and mangrove migration from sea-level rise will vary by county and watershed but greater in western Gulf States than in the eastern Gulf States where millions of hectares of coastal forest will be displaced over the next century with a near meter rise in relative sea level alone. Substantial losses of coastal forests will also occur in the eastern Gulf but mangrove forests in subtropical zones of Florida are expected to replace retreating freshwater forest and affect regional biodiversity. Accelerated global eustacy from climate change will compound the degree of predicted retreat and migration of coastal forests with expected implications for ecosystem management of State and Federal lands in the absence of adaptive coastal management.

The use of carbon adsorbents for the removal of perfluoroalkyl acids from potable reuse systems.

Science.gov (United States)

Inyang, Mandu; Dickenson, Eric R V

2017-10-01

Bench- and pilot-scale sorption tests were used to probe the performance of several biochars at removing perfluoroalkyl acids (PFAA) from field waters, compared to granular activated carbon (GAC). Screening tests using organic matter-free water resulted in hardwood (HWC) (K d  = 41 L g -1 ) and pinewood (PWC) (K d  = 49 L g -1 ) biochars having the highest perfluorooctanoic acid (PFOA) removal performance that was comparable to bituminous coal GAC (K d  = 41 L g -1 ). PWC and HWC had a stronger affinity for PFOA sorbed in Lake Mead surface water (K F  = 11 mg (1-n) L n g -1 ) containing a lower (2 mg L -1 ) dissolved organic carbon (DOC) concentration than in a tertiary-filtered wastewater (K F  = 8 mg (1-n) L n g -1 ) with DOC of 4.9 mg L -1 . A pilot-scale study was performed using three parallel adsorbers (GAC, anthracite, and HWC biochar) treating the same tertiary-filtered wastewater. Compared to HWC, and anthracite, GAC was the most effective in mitigating perfluoropentanoic acid (PFPnA), perfluorohexanoic acid (PHxA), PFOA, perfluorooctane sulfonic acid (PFOS), and DOC (45-67% removed at 4354 bed volumes) followed by HWC, and then anthracite. Based on bench- and pilot-scale results, shorter-chain PFAA [perfluorobutanoic acid (PFBA), PFPnA, or PFHxA] were more difficult to remove with both biochar and GAC than the longer-chain, PFOS and PFOA. Copyright © 2017 Elsevier Ltd. All rights reserved.

Stalagmite carbon isotopes and dead carbon proportion (DCP) in a near-closed-system situation: An interplay between sulphuric and carbonic acid dissolution

Science.gov (United States)

Bajo, Petra; Borsato, Andrea; Drysdale, Russell; Hua, Quan; Frisia, Silvia; Zanchetta, Giovanni; Hellstrom, John; Woodhead, Jon

2017-08-01

In this study, the 'dead carbon proportion' (DCP) calculated from combined U-Th and radiocarbon analyses was used to explore the carbon isotope systematics in Corchia Cave (Italy) speleothems, using the example of stalagmite CC26 which grew during the last ∼12 ka. The DCP values in CC26 are among the highest ever recorded in a stalagmite, spanning the range 44.8-68.8%. A combination of almost closed-system conditions and sulphuric acid dissolution (SAD) are proposed as major drivers in producing such a high DCP with minor contribution from old organic matter from the deep vadose zone. The long-term decrease in both DCP and δ13C most likely reflects post-glacial soil recovery above the cave, with a progressive increase of soil CO2 contribution to the total dissolved inorganic carbon (DIC). Pronounced millennial-scale shifts in DCP and relatively small coeval but antipathetic changes in δ13C are modulated by the effects of hydrological variability on open and closed-system dissolution, SAD and prior calcite precipitation. Hence, the DCP in Corchia Cave speleothems represents an additional proxy for rainfall amount.

Yoga Retreat : Grafiikan työstäminen Facebook peliin

OpenAIRE

Kälviäinen, Jenna

2013-01-01

In the thesis the process of graphic design of Facebook games is discussed. The Author got an opportunity to work as a graphic designer for Gajatri Studios in their first video game project called Yoga Retreat. Experiences from the project, the decisions made and the problems faced were analyzed in detail. In the theory section the history of Facebook in general was explored and the question of how Facebook became one of the most well-known websites of the Internet was discussed as well as...

Retreatment with peg-interferon and ribavirin in patients with chronic hepatitis C virus genotype 2 or 3 infection with prior relapse

DEFF Research Database (Denmark)

Lagging, Martin; Rembeck, Karolina; Rauning Buhl, Mads

2013-01-01

Uncertainty remains regarding the efficacy of retreatment with current standard-of-care peg-interferon (peg-IFN) and ribavirin among patients infected with hepatitis C virus (HCV) genotypes 2 or 3 with relapse after prior therapy.......Uncertainty remains regarding the efficacy of retreatment with current standard-of-care peg-interferon (peg-IFN) and ribavirin among patients infected with hepatitis C virus (HCV) genotypes 2 or 3 with relapse after prior therapy....

Surface modification of pitch-based spherical activated carbon by CVD of NH3 to improve its adsorption to uric acid

International Nuclear Information System (INIS)

Liu Chaojun; Liang Xiaoyi; Liu Xiaojun; Wang Qin; Zhan Liang; Zhang Rui; Qiao Wenming; Ling Licheng

2008-01-01

Surface chemistry of pitch-based spherical activated carbon (PSAC) was modified by chemical vapor deposition of NH 3 (NH 3 -CVD) to improve the adsorption properties of uric acid. The texture and surface chemistry of PSAC were studied by N 2 adsorption, pH PZC (point of zero charge), acid-base titration and X-ray photoelectron spectroscopy (XPS). NH 3 -CVD has a limited effect on carbon textural characteristics but it significantly changed the surface chemical properties, resulting in positive effects on uric acid adsorption. After modification by NH 3 -CVD, large numbers of nitrogen-containing groups (especially valley-N and center-N) are introduced on the surface of PSAC, which is responsible for the increase of pH PZC , surface basicity and uric acid adsorption capacity. Pseudo-second-order kinetic model can be used to describe the dynamic adsorption of uric acid on PSAC, and the thermodynamic parameters show that the adsorption of uric acid on PSAC is spontaneous, endothermic and irreversible process in nature

Surface modification of pitch-based spherical activated carbon by CVD of NH 3 to improve its adsorption to uric acid