WorldWideScience

Sample records for acid degradation progress

  1. On an orthotropic model for progressive degradation

    Hammer, Velaja B.; Pedersen, Pauli

    1999-01-01

    Progressive degradation in orthotropic materials is modelled from a smear-out point of view, and physical measurable quantities are used as the describing parameters. Evolution of stiffness and evolution of strength are kept uncoupled. For plane problems the stiffness evolution is modelled by the...

  2. Degradation of ascorbic acid in ethanolic solutions.

    Hsu, Hsin-Yun; Tsai, Yi-Chin; Fu, Chi-Chang; Wu, James Swi-Bea

    2012-10-24

    Ascorbic acid occurs naturally in many wine-making fruits. The industry also uses ascorbic acid as an antioxidant and color stabilizer in the making of alcoholic beverages including white wine, wine cooler, alcopop, and fruit liqueur. However, the degradation of ascorbic acid itself may cause browning and the deterioration of color quality. This study was aimed to monitor the degradation of ascorbic acid, the formation of degradation products, and the browning in storage of ascorbic acid containing 0-40% (v/v) ethanolic solutions buffered at pH 3.2 as models of alcoholic beverages. The results show that ascorbic acid degradation in the ethanolic solutions during storage follows first-order reaction, that the degradation and browning rates increase with the increase of ethanol concentration, that the activation energy for the degradation of ascorbic acid is in the range 10.35-23.10 (kcal/mol), that 3-hydroxy-2-pyrone is an indicator and a major product of ascorbic acid degradation, and that aerobic degradation pathway dominants over anaerobic pathway in ascorbic acid degradation in ethanolic solutions. PMID:22994409

  3. [Progress in glucaric acid].

    Qiu, Yuying; Fang, Fang; Du, Guocheng; Chen, Jian

    2015-04-01

    Glucaric acid (GA) is derived from glucose and commonly used in chemical industry. It is also considered as one of the "Top value-added chemicals from biomass" as carbohydrate monomers to produce various synthetic polymers and bioenergy. The demand for GA in food manufacture is increasing. GA has also attracted public attentions due to its therapeutic uses such as regulating hormones, increasing the immune function and reducing the risks of cancers. Currently GA is produced by chemical oxidation. Research on production of GA via microbial synthesis is still at preliminary stage. We reviewed the advances of glucaric acid applications, preparation and quantification methods. The prospects on production of GA by microbial fermentation were also discussed. PMID:26380405

  4. Cyclopiazonic acid degradation by aqueous ozone

    Silva, Otniel Freitas; Venâncio, Armando

    2011-01-01

    Ozone is a chemical agent with great potential to reduce mycotoxins, it was effective against to reduce some mycotoxins. In view of this it was aimed of this work study the Cyclopiazonic acid (CPA) degradation by aqueous ozone. The degradation of exogenously CPA introduced in mobile phase was confirmed by High performance liquid Chromatography (HPLC). In parallel it was tested the effect of sodium formate (SF), to evaluate the influence of this chemical to neutralize ...

  5. 除草剂2,4-滴微生物降解研究进展%Research Progress of Microbial Degradation of the Herbicide 2,4-Dichlorophenoxyacetic Acid

    韩丽珍; 赵德刚

    2012-01-01

    高浓度2,4-滴是一种合成激素类除草剂,可有效防除阔叶杂草,微生物降解是其在环境中的主要代谢途径.综述了2,4-滴的除草作用机制、降解微生物、降解基因、矿化途径、污染物的微生物修复及抗性转基因作物的研究进展,展望了2,4-滴降解基因在环境污染修复中的应用以及抗2,4-滴转基因作物作为草甘膦抗性作物补充的前景.%2,4-Dichlorophenoxyacetic acid(2,4-D) at high concentration is a kind of synthetic auxin herbicides, which could control dicotyledonous weeds effectively. This herbicide is mostly depended on microbial degradation in a natural environment. The function mechanism of weeding, resources of degrading microorganism and metabolism genes, mineralization way of herbicide 2,4-D were reviewed in this paper. Reviewed the studying progress on microbial remediation for pollutant and 2,4-D-resistant transgenic crops. The application of 2,4-D degrading genes in pollutant bioremediation was prospected. And 2,4-D resistant genetically modified plant is suggested to become a benefical supplement of glyphosate-resistant crops.

  6. Radiolytic degradation of sorbic acid in isolated systems

    Effect of Co(60) gamma-irradiation on stability of sorbic acid (SA) in solutions, dough and chapaties has been investigated. SA was highly susceptible to radiolytic degradation in aqueous systems. Rate of degradation decreased with rise in pH. Sugars, hydrocolloids except pectin, citric acid, lactic acid, malic acid, arginine and threonine, catalyzed degradation while oxalic acid, maleic acid, Cu2+, nitrite, nitrate and phthalate had protective effects. SA was more stable in alcohols and vegetable oils than in aqueous solutions. In wheat flour radiolytic degradation of SA was less at lower moisture. Relatively SA was more stable in chapaties than in dough. Gelatinization and addition of oil in dough reduced degradation of SA

  7. [Degradation of oxytetracycline with ozonation in acetic acid solvent].

    Li, Shi-Yin; Li, Xiao-Rong; Zhu, Yi-Ping; Zhu, Jiang-Peng; Wang, Guo-Xiang

    2012-12-01

    Use acetic acid as the media of ozone degradation of oxytetracycline (OTC), and effects of the initial dosing ratio of ozone/OTC, ozone flow, free radical scavenger, metal ions on the removal rate of OTC were investigated respectively. The results showed that acetic acid had a high ozone stability and solubility. OTC had a high removal rate and degradation rate in acetic acid solution. With the increase of OTC dosage, the removal rate of OTC decreased in acetic acid. Removal rate of OTC was increased distinctly when ozone flow increased properly. It was also observed that free radical scavenger had a significantly negative effect on OTC ozonation degradation in acetic acid. Furthermore the main reactions of OTC ozone oxidation were direct oxidation and indirect oxidation in acetic acid. When Fe3+ and Co2+ were existent in acetic acid, the degradation of OTC was inhibited significantly. PMID:23379161

  8. Fatty Acid Structure and Degradation Analysis in Fingerprint Residues.

    Pleik, Stefanie; Spengler, Bernhard; Schäfer, Thomas; Urbach, Dieter; Luhn, Steven; Kirsch, Dieter

    2016-09-01

    GC-MS investigations were carried out to elucidate the aging behavior of unsaturated fatty acids in fingerprint residues and to identify their degradation products in aged samples. For this purpose, a new sample preparation technique for fingerprint residues was developed that allows producing N-methyl-N-trimethylsilyl-trifluoroacetamide (MSTFA) derivatives of the analyzed unsaturated fatty acids and their degradation products. MSTFA derivatization catalyzed by iodotrimethylsilane enables the reliable identification of aldehydes and oxoacids as characteristic MSTFA derivatives in GCMS. The obtained results elucidate the degradation pathway of unsaturated fatty acids. Our study of aged fingerprint residues reveals that decanal is the main degradation product of the observed unsaturated fatty acids. Furthermore, oxoacids with different chain lengths are detected as specific degradation products of the unsaturated fatty acids. The detection of the degradation products and their chain length is a simple and effective method to determine the double bond position in unsaturated compounds. We can show that the hexadecenoic and octadecenoic acids found in fingerprint residues are not the pervasive fatty acids Δ9-hexadecenoic (palmitoleic acid) and Δ9-octadecenoic (oleic acid) acid but Δ6-hexadecenoic acid (sapienic acid) and Δ8-octadecenoic acid. The present study focuses on the structure identification of human sebum-specific unsaturated fatty acids in fingerprint residues based on the identification of their degradation products. These results are discussed for further investigations and method developments for age determination of fingerprints, which is still a tremendous challenge because of several factors affecting the aging behavior of individual compounds in fingerprints. Graphical Abstract ᅟ. PMID:27324649

  9. Hydrolytic degradation behaviour of sucrose palmitate reinforced poly(lactic acid) nanocomposites.

    Valapa, Ravi Babu; G, Pugazhenthi; Katiyar, Vimal

    2016-08-01

    This work discusses the influence of novel biofiller, "sucrose palmitate" (SP) on the hydrolytic degradation behavior of poly(lactic acid) (PLA) nanocomposites. The influence of temperature and pH of the solution on the hydrolytic degradation behavior of PLA and PLA-SP nanocomposites was investigated. The variation in the crystallinity of PLA and PLA composites subjected to the hydrolytic degradation process is verified by XRD and DSC analysis. The morphological changes that occurred during the degradation process are observed by scanning electron microscopy (SEM). Thermo-gravimetric analysis confirms the loss of thermal stability of the neat PLA as well as composites after hydrolytic degradation process. Transparency measurements support the enhancement in opacity of both the PLA and PLA-SP nanocomposites with progress in hydrolytic degradation period. PMID:27095433

  10. Degradation of caffeic acid in subcritical water and online HPLC-DPPH assay of degradation products.

    Khuwijitjaru, Pramote; Suaylam, Boonyanuch; Adachi, Shuji

    2014-02-26

    Caffeic acid was subjected to degradation under subcritical water conditions within 160-240 °C and at a constant pressure of 5 MPa in a continuous tubular reactor. Caffeic acid degraded quickly at these temperatures; the main products identified by liquid chromatography-diode array detection/mass spectrometry were hydroxytyrosol, protocatechuic aldehyde, and 4-vinylcatechol. The reaction rates for the degradation of caffeic acid and the formation of products were evaluated. Online high-performance liquid chromatography/2,2-diphenyl-1-picryhydrazyl assay was used to determine the antioxidant activity of each product in the solution. It was found that the overall antioxidant activity of the treated solution did not change during the degradation process. This study showed a potential of formation of antioxidants from natural phenolic compounds under these subcritical water conditions, and this may lead to a discovering of novel antioxidants compounds during the extraction by this technique. PMID:24483598

  11. Amino Acid Degradation after Meteoritic Impact Simulation

    Bertrand, M.; Westall, F.; vanderGaast, S.; Vilas, F.; Hoerz, F.; Barnes, G.; Chabin, A.; Brack, A.

    2008-01-01

    Amino acids are among the most important prebiotic molecules as it is from these precursors that the building blocks of life were formed [1]. Although organic molecules were among the components of the planetesimals making up the terrestrial planets, large amounts of primitive organic precursor molecules are believed to be exogenous in origin and to have been imported to the Earth via micrometeorites, carbonaceous meteorites and comets, especially during the early stages of the formation of the Solar System [1,2]. Our study concerns the hypothesis that prebiotic organic matter, present on Earth, was synthesized in the interstellar environment, and then imported to Earth by meteorites or micrometeorites. We are particularly concerned with the formation and fate of amino acids. We have already shown that amino acid synthesis is possible inside cometary grains under interstellar environment conditions [3]. We are now interested in the effects of space conditions and meteoritic impact on these amino acids [4-6]. Most of the extraterrestrial organic molecules known today have been identified in carbonaceous chondrite meteorites [7]. One of the components of these meteorites is a clay with a composition close to that of saponite, used in our experiments. Two American teams have studied the effects of impact on various amino acids [8,9]. [8] investigated amino acids in saturated solution in water with pressure ranges between 5.1 and 21 GPa and temperature ranges between 412 and 870 K. [9] studied amino acids in solid form associated with and without minerals (Murchison and Allende meteorite extracts) and pressure ranges between 3 and 30 GPa. In these two experiments, the amino acids survived up to 15 GPa. At higher pressure, the quantity of preserved amino acids decreases quickly. Some secondary products such as dipeptides and diketopiperazins were identified in the [8] experiment.

  12. The identification and degradation of isosaccharinic acid, a cellulose degradation product

    Nirex is seeking to develop a deep underground repository for the disposal of solid intermediate-level and low-level radioactive wastes (ILW and LLW) in the UK. One possible influence on the behavior of radionuclides is the formation of water-soluble complexants by the degradation of the solid organic polymers that will be present in the wastes. The degradation products of cellulose have been shown to increase the solubility of plutonium and other radionuclides and to reduce sorption onto near-field and far-field materials. Degradation of cellulose under anaerobic alkaline conditions produces a range of organic acids. In this paper 2-C-(hydroxymethyl)-3-deoxy-D-pentonic acid (isosaccharinic acid, ISA) is identified by High Performance Liquid Chromatography as a significant component of cellulose leachates. A combination of fractionation of cellulose leachates and plutonium solubility determinations shows that ISA is responsible for the majority of the enhancement of plutonium solubility observed in such leachates. Further degradation of ISA by chemical or microbial action may lessen the effect of degraded cellulose leachates. Experiment studies on the chemical degradation of this compound under alkaline conditions suggest that the presence of oxygen is required. Microbial degradation studies show that the plutonium solubility in solutions of ISA is reduced by their exposure to microbial action

  13. The influences of elastomer toward degradability of poly (lactic acid)

    Kaavessina, Mujtahid; Distantina, Sperisa; Chafidz, Achmad; Fadilah, Al-Zahrani, Saeed M.

    2016-02-01

    Poly (lactic acid)/elastomer blends were prepared via direct injection molding with the different weight fractions of elastomer, namely: 0, 10, 20 and 30 wt%. Degradation test of poly (lactic acid) (PLA) was performed by burial in the soil. The physical appearance and thermal properties of the tested specimens were monitored periodically. The presence of elastomer tended to significantly increase the degradability of PLA after buried for 27 weeks. With 30 wt% elastomer, the color and the surface of specimens become more white and rougher due to the degradation. Differential scanning calorimetry (DSC) was used to evaluate thermal properties and crystallinity of all samples. It was found that the melting temperature decreased as the amount of elastomer increased. The crystallinity showed that the degradation of PLA is occurred firstly in amorphous phase.

  14. Degradation modelling of concrete submitted to sulfuric acid attack

    Yuan, Haifeng; Dangla, Patrick; Chatellier, Patrice; Chaussadent, Thierry

    2013-01-01

    Bio-deterioration of concrete,which is very common in sewer system and waste water treatment plant, results in significant structure degradation. Normally, the process can be described by the two following steps: Biochemical reactions producing biogenic aggressive species (H2SO4 is one of the most significant biogenic acid in sewer pipes), and chemical reactions between biogenic aggressive species and cement hydration products which is responsible for concrete degradation. A reactive transpor...

  15. Degradation of hyaluronic acid, poly- and monosaccharides, and model compounds by hypochlorite

    Hawkins, C L; Davies, Michael Jonathan

    1998-01-01

    Degradation of hyaluronic acid by oxidants such as HO. and HOCl/CIO- is believed to be important in the progression of rheumatoid arthritis. While reaction of hyaluronic acid with HO. has been investigated extensively, reaction with HOCl/ClO- is less well defined. Thus, little is known about the...... site(s) of HOCl/ClO- attack, the intermediates formed, or the mechanism(s) of polymer degradation. In this study reaction of HOCl/ClO- with amides, sugars, polysaccharides, and hyaluronic acid has been monitored by UV-visible (220-340 nm) and EPR spectroscopy. UV-visible experiments have shown that......--C bond. The nature of the radicals formed has been investigated by EPR spin trapping. Reaction of HOCl/ClO- with hyaluronic acid, chondroitin sulphates A and C, N-acetyl sugars, and amides gave novel, carbon-centered, spin adducts, the formation of which is consistent with selective initial attack at the...

  16. Tannic acid degradation by Klebsiella strains isolated from goat feces

    Arezoo Tahmourespour

    2016-03-01

    Full Text Available Background and Objectives: Tannins are toxic polyphenols that either bind and precipitate or condense proteins. The high tannin content of some plants is the preliminary limitation of using them as a ruminant feed. So, the aim of this study was the isolation and characterization of tannic acid degrading bacterial strains from goat feces before and after feeding on Pis- tachio-Soft Hulls as tannin rich diet (TRD.Materials and Methods: Bacterial strains capable of utilizing tannic acid as sole carbon and energy source were isolated and characterized from goat feces before and after feeding on TRD. Tannase activity, maximum tolerable concentration and biodegradation potential were assessed.Results: Four tannase positive isolates were identified as Klebsiella pneumoniae. Isolated strains showed the maximum tolerable concentration of 64g/L of tannin. The tannic acid degradation percentage at a concentration of 15.0 g/L reached a maximum of 68% after 24 h incubation, and more than 98% after 72 h incubation. The pH of the medium also decreased along with tannic acid utilization.Conclusions: It is obvious that TRD induced adaptive responses. Thus, while the bacteria were able to degrade and detoxify the tannic acids, they had to adapt in the presence of high concentrations of tannic acid. So, these isolates have an amazing potential for application in bioremediation, waste water treatment, also reduction of tannins antinutritional effects in animal feeds.Keywords: Biodegradation; Goat feces; Klebsiella strains; Tannic acid

  17. Varying Conditions for Hexanoic Acid Degradation with BioTiger™

    Foreman, Koji [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Milliken, Charles [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Brigmon, Robin [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2016-07-27

    BioTiger™ (BT) is a consortium of 12 bacteria designed for petroleum waste biodegradation. BT is currently being studied and could be considered for bioremediation of the Athabasca oil sands refineries in Canada and elsewhere. The run off ponds from the petroleum extraction processes, called tailings ponds, are a mixture of polycyclic aromatic hydrocarbons, naphthenic acids, hydrocarbons, toxic chemicals like heavy metals, water, and sand. Due to environmental regulations the oil industry would like to separate and degrade the hazardous chemical species from the tailings ponds while recycling the water. It has been shown that BT at 30 C° is able to completely degrade 10 mM hexanoic acid (HA) cometabolically with 0.2% yeast extract (w/v) in 48 hours when starting at 0.4 OD 600nm. After establishing this stable degradation capability, variations were tested to explore the wider parameters of BT activity in temperature, pH, intermediate degradation, co-metabolic dependence, and transfer stability. Due to the vast differences in temperature at various points in the refineries, a wide range of temperatures were assessed. The results indicate that BT retains the ability to degrade HA, a model surrogate for tailings pond contaminants, at temperatures ranging from 15°C to 35°C. Hexanamide (HAM) was shown to be an intermediate generated during the degradation of HA in an earlier work and HAM is completely degraded after 48 hours, indicating that HAM is not the final product of HA degradation. Various replacements for yeast extract were attempted. Glucose, a carbon source; casein amino acids, a protein source; additional ammonia, mimicking known media; and additional phosphate with Wolffe’s vitamins and minerals all showed no significant degradation of HA compared to control. Decreasing the yeast extract concentration (0.05%) demonstrated limited but significant degradation. Finally, serial inoculations of BT were performed to determine the stability of degradation

  18. Ultrasonic Monitoring of the Progress of Lactic Acid Fermentation

    Masuzawa, Nobuyoshi; Kimura, Akihiro; Ohdaira, Etsuzo

    2003-05-01

    Promotion of lactic acid fermentation by ultrasonic irradiation has been attempted. It is possible to determine the progress of fermentation and production of a curd, i.e., yoghurt and or kefir, by measuring acidity using a pH meter. However, this method is inconvenient and indirect for the evaluation of the progress of lactic acid fermentation under anaerobic condition. In this study, an ultrasonic monitoring method for evaluating the progress of lactic acid fermentation was examined.

  19. Degradation of 2-hydroxybenzoic acid by advanced oxidation processes

    C. L. P. S. Zanta; Martínez-Huitle, C. A.

    2009-01-01

    In this study, advanced oxidation processes (AOPs) such as the UV/H2O2 and Fenton processes were investigated for the degradation of 2-hydroxybenzoic acid (2-HBA) in lab-scale experiments. Different [H2O2]/[2-HBA] molar ratios and pH values were used in order to establish the most favorable experimental conditions for the Fenton process. For comparison purposes, degradation of 2-HBA was carried out by the UV/H2O2 process under Fenton experimental conditions. The study showed that the Fenton p...

  20. Hydrolytically Degradable Hyaluronic Acid Hydrogels with Controlled Temporal Structures

    Sahoo, Sujata; CHUNG, CINDY; Khetan, Sudhir; Burdick, Jason A.

    2008-01-01

    Polysaccharides are being processed into biomaterials for numerous biological applications due to their native source in numerous tissues and biological functions. For instance, hyaluronic acid (HA) is found abundantly in the body, interacts with cells through surface receptors, and can regulate cellular behavior (e.g., proliferation, migration). HA was previously modified with reactive groups to form hydrogels that are degraded by hyaluronidases, either added exogenously or produced by cells...

  1. Oxidative degradation of salicylic acid by sprayed WO3 photocatalyst

    Highlights: • The photoactivity of sprayed WO3 thin film. • Photoelectrocatalytic degradation of salicylic acid. • Reaction kinetics and mineralization of pollutants by COD. - Abstract: The WO3 thin films were deposited using spray pyrolysis technique. The prepared WO3 thin films were characterized using photoelectrochemical (PEC), X-ray diffraction, atomic force microscopy (AFM), and UV–vis absorbance spectroscopy techniques. PEC measurements of WO3 films deposited at different deposition temperatures were carried out to study photoresponse. The maximum photocurrent (Iph = 261 μA/cm2) was observed for the film deposited at the 225 °C. The monoclinic crystal structure of WO3 has been confirmed from X-ray diffraction studies. AFM studies were used to calculate particle size and average roughness of the films. Optical absorbance was studied to estimate the bandgap energy of WO3 thin film which was about 2.65 eV. The photoelectrocatalytic activity of WO3 film was studied by degradation of salicylic acid with reducing concentrations as function of reaction time. The WO3 photocatalyst degraded salicylic acid to about 67.14% with significant reduction in chemical oxygen demand (COD) value

  2. Degradation of 3-phenoxybenzoic acid by a Bacillus sp.

    Shaohua Chen

    Full Text Available 3-Phenoxybenzoic acid (3-PBA is of great environmental concern with regards to endocrine disrupting activity and widespread occurrence in water and soil, yet little is known about microbial degradation in contaminated regions. We report here that a new bacterial strain isolated from soil, designated DG-02, was shown to degrade 95.6% of 50 mg·L(-1 3-PBA within 72 h in mineral salt medium (MSM. Strain DG-02 was identified as Bacillus sp. based on the morphology, physio-biochemical tests and 16S rRNA sequence. The optimum conditions for 3-PBA degradation were determined to be 30.9°C and pH 7.7 using response surface methodology (RSM. The isolate converted 3-PBA to produce 3-(2-methoxyphenoxy benzoic acid, protocatechuate, phenol, and 3,4-dihydroxy phenol, and subsequently transformed these compounds with a q(max, K(s and K(i of 0.8615 h(-1, 626.7842 mg·L(-1 and 6.7586 mg·L(-1, respectively. A novel microbial metabolic pathway for 3-PBA was proposed on the basis of these metabolites. Inoculation of strain DG-02 resulted in a higher degradation rate on 3-PBA than that observed in the non-inoculated soil. Moreover, the degradation process followed the first-order kinetics, and the half-life (t(1/2 for 3-PBA was greatly reduced as compared to the non-inoculated control. This study highlights an important potential application of strain DG-02 for the in situ bioremediation of 3-PBA contaminated environments.

  3. Efficient sonochemical degradation of perfluorooctanoic acid using periodate.

    Lee, Yu-Chi; Chen, Meng-Jia; Huang, Chin-Pao; Kuo, Jeff; Lo, Shang-Lien

    2016-07-01

    A rapid and efficient treatment method, using periodate (PI) for sonochemical oxidation of persistent and bioaccumulative perfluorooctanoic acid (PFOA) was developed. With an addition of 45mM PI, 96.5% of PFOA was decomposed with a defluorination efficiency of 95.7% after 120min of ultrasound (US). The removals of PFOA were augmented with an increase in PI doses. In all the PI+US experimental runs, decomposition efficiencies were essentially similar to those of defluorination, indicating that PFOA was decomposed and mineralized into fluoride ions. Lower solution pHs resulted in an increase in decomposition and defluorination efficiencies of PFOA due to acid-catalyzation. Dissolved oxygen increased the amount of IO4 radicals produced, which consumed the more effective IO3 radicals. Consequently, presence of oxygen inhibited the destruction of PFOA. The PFOA degradation rates with different gases sparging are in the following order: nitrogen>air>oxygen. Effects of anions follow the Hofmeister effects on PFOA degradation (i.e., Br(-)>none⩾Cl(-)>SO4(2)(-)). Br(-) could react with OH to yield radical anion Br2(-) that enhances the PFOA degradation. A reaction pathway was also proposed to describe the PI oxidation of PFOA under US irradiation. PMID:26964977

  4. Perfluorooctanoic Acid Degradation Using UV-Persulfate Process: Modeling of the Degradation and Chlorate Formation.

    Qian, Yajie; Guo, Xin; Zhang, Yalei; Peng, Yue; Sun, Peizhe; Huang, Ching-Hua; Niu, Junfeng; Zhou, Xuefei; Crittenden, John C

    2016-01-19

    In this study, we investigated the destruction and by-product formation of perfluorooctanoic acid (PFOA) using ultraviolet light and persulfate (UV-PS). Additionally, we developed a first-principles kinetic model to simulate both PFOA destruction and by-product and chlorate (ClO3(-)) formation in ultrapure water (UW), surface water (SW), and wastewater (WW). PFOA degradation was significantly suppressed in the presence of chloride and carbonate species and did not occur until all the chloride was converted to ClO3(-) in UW and for low DOC concentrations in SW. The model was able to simulate the PS decay, pH changes, radical concentrations, and ClO3(-) formation for UW and SW. However, our model was unable to simulate PFOA degradation well in WW, possibly from PS activation by NOM, which in turn produced sulfate radicals. PMID:26686982

  5. Degradation of p-hydroxyphenylacetic acid by photoassisted Fenton reaction.

    Acero, L L; Benítez, F J; Real, F J; Leal, A I

    2001-01-01

    The chemical decomposition of p-hydroxyphenylacetic acid, a phenolic pollutant present in agro-industrial plant effluents, has been investigated by means of the Fenton's reaction and the photoassisted Fenton's reaction, the so-called photo-Fenton system. The degradation levels achieved have been compared to those obtained by applying other Advanced Oxidation Processes, such as the combination UV/H2O2. The optimum pH to carry out the decomposition of this organic compound by either Fenton or photo-Fenton systems was found to be pH = 3. The presence of buffers such as phosphate impedes these processes due to the formation of ferric complexes. A reaction mechanism, which allows calculating the contribution of the radical reaction to the global process, has been proposed. According to this mechanism, the dominant way of degradation of p-hydroxyphenylacetic acid is through its reaction with the OH radicals originated in the photolysis of H2O2 and, especially, in the Fenton's reaction. PMID:11695475

  6. Phenolic acid degradation potential and growth behavior of lactic acid bacteria in sunflower substrates.

    Fritsch, Caroline; Heinrich, Veronika; Vogel, Rudi F; Toelstede, Simone

    2016-08-01

    Sunflower flour provides a high content of protein with a well-balanced amino acid composition and is therefore regarded as an attractive source for protein. The use for human nutrition is hindered by phenolic compounds, mainly chlorogenic acid, which can lead under specific circumstances to undesirable discolorations. In this study, growth behavior and degradation ability of chlorogenic acid of four lactic acid bacteria were explored. Data suggested that significant higher fermentation performances on sunflower flour as compared to sunflower protein concentrate were reached by Lactobacillus plantarum, Pediococcus pentosaceus, Lactobacillus gasseri and Bifidobacterium animalis subsp. lactis. In fermentation with the latter two strains reduced amounts of chlorogenic acid were observed in sunflower flour (-11.4% and -19.8%, respectively), which were more pronounced in the protein concentrate (-50.7% and -95.6%, respectively). High tolerances against chlorogenic acid and the cleavage product quinic acid with a minimum inhibitory concentration (MIC) of ≥20.48 mg/ml after 48 h were recorded for all strains except Bifidobacterium animalis subsp. lactis, which was more sensitive. The second cleavage compound, caffeic acid revealed a higher antimicrobial potential with MIC values of 0.64-5.12 mg/ml. In this proof of concept study, degradation versus inhibitory effect suggest the existence of basic mechanisms of interaction between phenolic acids in sunflower and lactic acid bacteria and a feasible way to reduce the chlorogenic acid content, which may help to avoid undesired color changes. PMID:27052717

  7. Docosahexaenoic acid ester degradation measured by FTIR-ATR with correlation spectroscopy

    Highly unsaturated fatty acids such as docosahexaenoic acid and linolenic acid are prone to oxidation with a resulting loss of bioactivity and generation of malodorous degradation compounds. Degradation proceeds by formation of the corresponding hydroperoxyl free radical with subsequent oxidative cl...

  8. In vitro Degradation of Butanediamine-Grafted Poly(DL-Lactic acids)

    2007-01-01

    The degradation of butanediamine-grafted poly(DL-lactic acid) polymers (BDPLAs) in vitro together with PDLLA and maleic anhydride-grafted poly(DL-lactic acid) polymers (MPLAs) was investigated by observation of the changes of the pH value of incubation media, and weight loss ratio during degradation duration of 12 weeks. The results reveal that the acidity of PDLLA degradation products was weakened or neutralized by grafting butanediamine onto PDLLA. A uniform degradation of BDPLAs was observed in comparison with an acidity-induced auto-accelerating degradation featured by PDLLA and MPLAs. The biodegradation behaviors of BDPLAs can be adjusted by controlling the content of BDA. BDPLAs might be a new derivative of PDLLA-based biodegradable materials for medical applications without acidity-caused irritations and acidity-induced auto-accelerating degradation behavior as that of PDLLA.

  9. Gradual surface degradation of restorative materials by acidic agents.

    Hengtrakool, Chanothai; Kukiattrakoon, Boonlert; Kedjarune-Leggat, Ureporn

    2011-01-01

    The aim of this study was to investigate the effect of acidic agents on surface roughness and characteristics of four restorative materials. Fifty-two discs were created from each restorative material: metal-reinforced glass ionomer cement (Ketac-S), resin-modified glass ionomer cement (Fuji II LC), resin composite (Filtek Z250), and amalgam (Valiant-PhD); each disc was 12 mm in diameter and 2.5 mm thick. The specimens were divided into four subgroups (n=13) and immersed for 168 hours in four storage media: deionized water (control); citrate buffer solution; green mango juice; and pineapple juice. Surface roughness measurements were performed with a profilometer, both before and after storage media immersion. Surface characteristics were examined using scanning electron microscopy (SEM). Statistical significance among each group was analyzed using two-way repeated ANOVA and Tukey's tests. Ketac-S demonstrated the highest roughness changes after immersion in acidic agents (pValiant-PhD and Filtek Z250 illustrated some minor changes over 168 hours. The mango juice produced the greatest degradation effect of all materials tested (p<0.05). SEM photographs demonstrated gradual surface changes of all materials tested after immersions. Of the materials evaluated, amalgam and resin composite may be the most suitable for restorations for patients with tooth surface loss. PMID:21903509

  10. Inherently antioxidant and antimicrobial tannic acid release from poly(tannic acid) nanoparticles with controllable degradability.

    Sahiner, Nurettin; Sagbas, Selin; Aktas, Nahit; Silan, Coskun

    2016-06-01

    From a natural polyphenol, Tannic acid (TA), poly(TA) nanoparticles were readily prepared using a single step approach with three different biocompatible crosslinkers; trimethylolpropane triglycidyl ether (TMPGDE), poly(ethylene glycol) diglycidyl ether (PEGGE), and trisodium trimetaphosphate (STMP). P(TA) particles were obtained with controllable diameters between 400 to 800nm with -25mV surface charge. The effect of synthesis conditions, such as the emulsion medium, pH values of TA solution, and the type of crosslinker, on the shape, size, dispersity, yield, and degradability of poly(Tannic Acid) (p(TA)) nanoparticles was systematically investigated. The hydrolytic degradation amount in physiological pH conditions of 5.4, 7.4, and 9.0 at 37.5°C were found to be in the order TMPGDEantimicrobial effects against common bacterial strains. More interestingly, with a higher concentration of p(TA) particles, higher blood clotting indices were obtained. PMID:26970821

  11. Acid attack on hydrated cement — Effect of mineral acids on the degradation process

    Gutberlet, T.; Hilbig, H.; Beddoe, R.E., E-mail: robin.beddoe@tum.de

    2015-08-15

    During acid attack on concrete structural components, a degraded layer develops whose properties as a protective barrier are decisive for durability. {sup 29}Si NMR spectroscopy and {sup 27}Al NMR spectroscopy were used with XRD to investigate the degraded layer on hardened cement paste exposed to HCl and H{sub 2}SO{sub 4}. The layer comprises an amorphous silica gel with framework silicates, geminate and single silanol groups in which Si is substituted by Al. Amorphous Al(OH){sub 3} and Fe(OH){sub 3} are present. The gel forms by polycondensation and cross-linking of C-A-S-H chains at AlO{sub 4} bridging tetrahedra. In the transition zone between the degraded layer and the undamaged material, portlandite dissolves and Ca is removed from the C-A-S-H phases maintaining their polymer structure at first. With HCl, monosulphate in the transition zone is converted into Friedel's salt and ettringite. With H{sub 2}SO{sub 4}, gypsum precipitates near the degradation front reducing the thickness of the transition zone and the rate of degradation.

  12. Acid attack on hydrated cement — Effect of mineral acids on the degradation process

    During acid attack on concrete structural components, a degraded layer develops whose properties as a protective barrier are decisive for durability. 29Si NMR spectroscopy and 27Al NMR spectroscopy were used with XRD to investigate the degraded layer on hardened cement paste exposed to HCl and H2SO4. The layer comprises an amorphous silica gel with framework silicates, geminate and single silanol groups in which Si is substituted by Al. Amorphous Al(OH)3 and Fe(OH)3 are present. The gel forms by polycondensation and cross-linking of C-A-S-H chains at AlO4 bridging tetrahedra. In the transition zone between the degraded layer and the undamaged material, portlandite dissolves and Ca is removed from the C-A-S-H phases maintaining their polymer structure at first. With HCl, monosulphate in the transition zone is converted into Friedel's salt and ettringite. With H2SO4, gypsum precipitates near the degradation front reducing the thickness of the transition zone and the rate of degradation

  13. Degradation and compatibility behaviors of poly(glycolic acid) grafted chitosan

    The films of poly(glycolic acid) grafted chitosan were prepared without using a catalyst to improve the degradable property of chitosan. The films were characterized by Fourier transform-infrared spectroscopy and X-ray photoelectron spectroscopy (XPS). The degradation of the poly(glycolic acid) grafted chitosan films were investigated in the lysozyme solution. In vitro degradation tests revealed that the degradation rate of poly(glycolic acid) grafted chitosan films increased dramatically compared with chitosan. The degradation rate of poly(glycolic acid) grafted chitosan films gradually increased with the increasing of the molar ratio of glycolic acid to chitosan. Additionally, the poly(glycolic acid) grafted chitosan films have good biocompatibility, as demonstrated by in vitro cytotoxicity of the extraction fluids. The biocompatible and biodegradable poly(glycolic acid) grafted chitosan would be an effective material with controllable degradation rate to meet the diverse needs in biomedical fields. - Highlights: ► Chitosan-g-poly(glycolic acid) copolymer was prepared without using a catalyst. ► Degradation rate of copolymer increased dramatically compared with that of chitosan. ► Degradation rate was controlled by the molar ratio of glycolic acid to chitosan. ► In vitro cytotoxicity tests revealed that the copolymer has good biocompatibility. ► The copolymer has a great potential to meet diverse needs in biomedical fields

  14. Phytic acid degrading lactic acid bacteria in tef-injera fermentation.

    Fischer, Maren M; Egli, Ines M; Aeberli, Isabelle; Hurrell, Richard F; Meile, Leo

    2014-11-01

    Ethiopian injera, a soft pancake, baked from fermented batter, is preferentially prepared from tef (Eragrostis tef) flour. The phytic acid (PA) content of tef is high and is only partly degraded during the fermentation step. PA chelates with iron and zinc in the human digestive tract and strongly inhibits their absorption. With the aim to formulate a starter culture that would substantially degrade PA during injera preparation, we assessed the potential of microorganisms isolated from Ethiopian household-tef fermentations to degrade PA. Lactic acid bacteria (LAB) were found to be among the dominating microorganisms. Seventy-six isolates from thirteen different tef fermentations were analyzed for phytase activity and thirteen different isolates of seven different species were detected to be positive in a phytase screening assay. In 20-mL model tef fermentations, out of these thirteen isolates, the use of Lactobacillus (L.) buchneri strain MF58 and Pediococcus pentosaceus strain MF35 resulted in lowest PA contents in the fermented tef of 41% and 42%, respectively of its initial content. In comparison 59% of PA remained when spontaneously fermented. Full scale tef fermentation (0.6L) and injera production using L. buchneri MF58 as culture additive decreased PA in cooked injera from 1.05 to 0.34±0.02 g/100 g, representing a degradation of 68% compared to 42% in injera from non-inoculated traditional fermentation. The visual appearance of the pancakes was similar. The final molar ratios of PA to iron of 4 and to zinc of 12 achieved with L. buchneri MF58 were decreased by ca. 50% compared to the traditional fermentation. In conclusion, selected LAB strains in tef fermentations can degrade PA, with L. buchneri MF58 displaying the highest PA degrading potential. The 68% PA degradation achieved by the application of L. buchneri MF58 would be expected to improve human zinc absorption from tef-injera, but further PA degradation is probably necessary if iron absorption has to

  15. Degradation of tannic acid by cell-free extracts of Lactobacillus plantarum

    Rodríguez, Héctor; Rivas, Blanca de las; Gómez-Cordovés, Carmen; Muñoz, Rosario

    2008-01-01

    The ability of Lactobacillus plantarum CECT 748T to degrade hydrolysable tannins was evaluated. Three commercial tannic acids were incubated in presence of cell-free extracts containing soluble proteins from L. plantarum. By HPLC analyses, almost a complete tannic acid degradation was observed in the three samples assayed. By using HPLC-DAD/ESI-MS, we partially determined the composition of tannic acid from Quercus infectoria galls. This tannic acid is a gallotannin mainly composed o...

  16. Effects of organic acids, amino acids and ethanol on the radio-degradation of patulin in an aqueous model system

    The effects of organic acids, amino acids, and ethanol on the radio-degradation of patulin by gamma irradiation in an aqueous model system were investigated. The patulin, dissolved in distilled water at a concentration of 50 ppm, was practically degraded by the gamma irradiation at the dose of 1.0 kGy, while 33% of the patulin remained in apple juice. In the aqueous model system, the radio-degradation of patulin was partially inhibited by the addition of organic acids, amino acids, and ethanol. The proportions of remaining patulin after irradiation with the dose of 1.0 kGy in the 1% solution of malic acid, citric acid, lactic acid, acetic acid, ascorbic acid, and ethanol were 31.4%, 2.3%, 31.2%, 6.1%, 50.8%, and 12.5%, respectively. During 30 days of storage, the remaining patulin was reduced gradually in the solution of ascorbic acid and malic acid compared to being stable in other samples. The amino acids, serine, threonine, and histidine, inhibited the radio-degradation of patulin. In conclusion, it was suggested that 1 kGy of gamma irradiation (recommended radiation doses for radicidation and/or quarantine in fruits) is effective for the reduction of patulin, but the nutritional elements should be considered because the radio-degradation effects are environment dependent

  17. Effects of organic acids, amino acids and ethanol on the radio-degradation of patulin in an aqueous model system

    Yun, Hyejeong [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Chonbuk, Jeongeup 580-185 (Korea, Republic of); Department of Food Science and Technology, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Lim, Sangyong [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Chonbuk, Jeongeup 580-185 (Korea, Republic of); Jo, Cheorun [Department of Animal Science and Biotechnology, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Chung, Jinwoo [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Chonbuk, Jeongeup 580-185 (Korea, Republic of); Kim, Soohyun [Glycomics Team, Korea Basic Science Institute, Daejeon 305-333 (Korea, Republic of); Kwon, Joong-Ho [Department of Food Science and Technology, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Kim, Dongho [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Chonbuk, Jeongeup 580-185 (Korea, Republic of)], E-mail: fungikim@kaeri.re.kr

    2008-06-15

    The effects of organic acids, amino acids, and ethanol on the radio-degradation of patulin by gamma irradiation in an aqueous model system were investigated. The patulin, dissolved in distilled water at a concentration of 50 ppm, was practically degraded by the gamma irradiation at the dose of 1.0 kGy, while 33% of the patulin remained in apple juice. In the aqueous model system, the radio-degradation of patulin was partially inhibited by the addition of organic acids, amino acids, and ethanol. The proportions of remaining patulin after irradiation with the dose of 1.0 kGy in the 1% solution of malic acid, citric acid, lactic acid, acetic acid, ascorbic acid, and ethanol were 31.4%, 2.3%, 31.2%, 6.1%, 50.8%, and 12.5%, respectively. During 30 days of storage, the remaining patulin was reduced gradually in the solution of ascorbic acid and malic acid compared to being stable in other samples. The amino acids, serine, threonine, and histidine, inhibited the radio-degradation of patulin. In conclusion, it was suggested that 1 kGy of gamma irradiation (recommended radiation doses for radicidation and/or quarantine in fruits) is effective for the reduction of patulin, but the nutritional elements should be considered because the radio-degradation effects are environment dependent.

  18. Radiation-induced degradation of cyclohexanebutyric acid in aqueous solutions by gamma ray irradiation

    Jia, Wenbao; He, Yanquan; Ling, Yongsheng; Hei, Daqian; Shan, Qing; Zhang, Yan; Li, Jiatong

    2015-04-01

    The radiation-induced degradation of cyclohexanebutyric acid under gamma ray irradiation was investigated. Degradation experiments were performed with 100 mL sealed Pyrex glass vessels loaded with 80 mL of cyclohexanebutyric acid solutions at various initial concentrations of 10, 20, and 40 mg L-1. The absorbed doses were controlled at 0, 0.65, 1.95, 3.25, 6.5, 9.75, and 13 kGy. The results showed that gamma ray irradiation could effectively degrade cyclohexanebutyric acid in aqueous solutions. The removal rate of cyclohexanebutyric acid increased significantly with the increase of absorbed dose and the decrease of its initial concentration. At the same time, the removal of chemical oxygen demand (COD) was as effective as that of cyclohexanebutyric acid. The kinetic studies showed that the degradation of cyclohexanebutyric acid followed pseudo first-order reaction. Above all, the proposed mechanism obtained when NaNO2, NaNO3 and tert-butanol were added showed that the •OH radical played a major role in the gamma degradation process of cyclohexanebutyric acid, while •H and eaq- played a minor role in the gamma degradation process. The degradation products were identified by Fourier transform infrared spectroscopy (FTIR) and gas chromatography/mass spectrometry (GC/MS) during cyclohexanebutyric acid degradation.

  19. Convergent synthesis of degradable dendrons based on L-malic acid

    Meyhoff, Ulrich; Riber, Ulla; Boas, Ulrik

    2015-01-01

    New degradable polyester dendrons based on the cellular tricarboxylic acid cycle component L-malic acid were synthesized up to the third generation by convergent synthesis. The dendron wedges could be introduced in a stepwise, highly regioselective fashion. HMBC-NMR revealed that the C1-carbonyl on...... malic acid was exclusively esterified, before the reaction of the second dendron wedge at C4 took place. Degradation studies on a first generation dendron analyzed by HPLC showed that hydrolytic degradation of the dendron most profoundly takes place at pH 4 and pH 9 with the highest degradation rate at...... alkaline pH. NMR shows that the dendron degrades to malic acid and fumaric acid derivatives. Preliminary studies performed in the cell culture show low toxicity of the dendrons in concentrations of up to 50 μg mL-1....

  20. Radiation-induced degradation of cyclohexanebutyric acid in aqueous solutions by gamma ray irradiation

    The radiation-induced degradation of cyclohexanebutyric acid under gamma ray irradiation was investigated. Degradation experiments were performed with 100 mL sealed Pyrex glass vessels loaded with 80 mL of cyclohexanebutyric acid solutions at various initial concentrations of 10, 20, and 40 mg L−1. The absorbed doses were controlled at 0, 0.65, 1.95, 3.25, 6.5, 9.75, and 13 kGy. The results showed that gamma ray irradiation could effectively degrade cyclohexanebutyric acid in aqueous solutions. The removal rate of cyclohexanebutyric acid increased significantly with the increase of absorbed dose and the decrease of its initial concentration. At the same time, the removal of chemical oxygen demand (COD) was as effective as that of cyclohexanebutyric acid. The kinetic studies showed that the degradation of cyclohexanebutyric acid followed pseudo first-order reaction. Above all, the proposed mechanism obtained when NaNO2, NaNO3 and tert-butanol were added showed that the ∙OH radical played a major role in the gamma degradation process of cyclohexanebutyric acid, while ∙H and eaq− played a minor role in the gamma degradation process. The degradation products were identified by Fourier transform infrared spectroscopy (FTIR) and gas chromatography/mass spectrometry (GC/MS) during cyclohexanebutyric acid degradation. - Highlights: • Gamma irradiation was efficient for removing cyclohexanebutyric acid from water. • The degradation kinetics of cyclohexanebutyric acid followed pseudo first-order reaction. • OH radical played a major role for oxidative degradation. • Some possible intermediate products were identified

  1. Kinetic study on the photocatalytic degradation of salicylic acid using ZnO catalyst

    The photocatalytic degradation of salicylic acid was studied by a batch process using ZnO as the catalyst on irradiation with UV light. The effect of process parameters such as pH, catalyst loading and initial concentration of salicylic acid on the extent of degradation was investigated. The degradation of salicylic acid was found to be effective in the neutral pH range. The optimum catalyst loading was observed at 2.0 g/L. The process followed first order kinetics and the apparent rate constant decreased with increase in the initial concentration of salicylic acid. The mechanism for the degradation of salicylic acid could be explained on the basis of Langmuir-Hinshelwood mechanism. The complete mineralization of salicylic acid was observed in the presence of ZnO photocatalyst. The ZnO was found to be quite stable and undergoes photocorrosion only to a negligible extent.

  2. Radiation induced degradation of ehtylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA) and dodecylbenzenesulfonic acid (DBS) in water

    The photolysis (λ=254 nm) of aqueous EDTA, NTA and DBS in the presence of oxygen, ozone and TiO2 individually and in mixtures of them as well as by ozonation only was investigated. Very high EDTA degradation yields were obtained by the synergistic action of UV light (λ=254 nm) in the presence of ozone and TiO2. By adding of a 2.5 mg.ml-1 TiO2 suspension to an aqueous solution of 1x10-3 mol.dm-3 EDTA and passing through 1.9 mg.dm-3.min-3O3 a Giph (-EDTA) = 12.0 and at 29.3 mg.dm-3.min-1O3 a Giph = 25.2 was obtained. Comparative studies were performed with γ-irradiation under similar conditions. A somewhat higher yield of EDTA degradation, Gi(-EDTA) = 13.5 was observed upon γ-radiolysis of 1x10-3 mol.dm-3 EDTA in the presence of 1.9 mg.dm-3.min-1O3 and 2.5 mg.ml-1 TiO2. In both cases the EDTA degradation depended on the absorbed radiation dose (UV-light or γ-rays), on the O3-concentration, and on the amount of suspended TiO2. By increasing the O3 concentration also the degradation yield was strongly increased. Analysis of products resulting from photolysis and radiolytic of EDTA, NTA and DBS in the presence of oxygen, performed by the GC/MS-method are also reported. Pulse Radiolysis and chemical analysis of DBS in aqueous solution were performed and the results are presented. Economic considerations concerning the pollutant degradation by combined photochemical methods in comparison to ionizing radiation under similar conditions of EDTA, NTA and DBS have been made. (author)

  3. Main chain acid-degradable polymers for the delivery of bioactive materials

    Frechet, Jean M. J.; Standley, Stephany M.; Jain, Rachna; Lee, Cameron C.

    2012-03-20

    Novel main chain acid degradable polymer backbones and drug delivery systems comprised of materials capable of delivering bioactive materials to cells for use as vaccines or other therapeutic agents are described. The polymers are synthesized using monomers that contain acid-degradable linkages cleavable under mild acidic conditions. The main chain of the resulting polymers readily degrade into many small molecules at low pH, but remain relatively stable and intact at physiological pH. The new materials have the common characteristic of being able to degrade by acid hydrolysis under conditions commonly found within the endosomal or lysosomal compartments of cells thereby releasing their payload within the cell. The materials can also be used for the delivery of therapeutics to the acidic regions of tumors and other sites of inflammation.

  4. Studies on radiolytic degradation of anion exchange resin under acidic condition

    With a view to understand the onset of degradation phenomenon of anion exchange resin used in PUREX process for the final purification of Pu, investigation were carried out to trace the chemical signature of radiolytic degradation species soluble in nitric acidic solutions. With this aim Dowex 1x 4 anion exchange resin was subjected to radiolytic degradation in presence of water and nitric acid medium of different strengths ranging from 2M to 7M. The aqueous acidic solutions have been analysed for the presence of aqueous soluble organic fragments arising from resin matrix and change in acidity. The extracted products have also been analysed by Gas chromatography. GLC fingerprint suggest of several degradation products especially at 7M nitric acid and dose of 87 Mrad. (author)

  5. Experimental and modeling study of Portland cement paste degradation in boric acid

    In the framework of Spent Fuel Pools (SFP) lifetime studies, an investigation of the Portland cement degradation in boric acid has been requested by the Electric Power Research Institute. The main goal of this study is to identify the physico-chemical degradation mechanisms involved in boric acid media. Both experimental and modeling approaches are considered. Concerning degradation experiments, sample of cement paste are immersed during three and nine months in a boric acid solution at 2400 ppm that is periodically renewed. Boric acid concentration has been chosen to be representative of SFP solution. Results will be confronted with reactive transport numerical calculations performed by the reactive transport code HYTEC associated with a dedicated extended database called Thermoddem. The analysis of degradation solution revealed a main ions release mechanism driven by diffusion especially for calcium, nitrate, sodium and sulfate. Leaching behavior of magnesium seems to be more complex. Decalcification is the major degradation process involved, even if a non-negligible contribution of further cations (Mg2+, Na+) and anions (SO42-) has been noticed. Analysis of degradation soution also revealed that kinetic of Portland cement paste degradation in boric acid is higher than in pure water, regarding the degraded depths measured and calcium leaching rate. This observation has been confirmed by solid characterization. Microstructure analysis of degraded Portland cement paste showed a global porosity increase in the degraded zone that might be mainly attributed to Portlandite dissolution. An Ettringite reprecipitation in the degraded zone has been suspected but could also be Ettringite-like phases containing boron. The analysis techniques used did not allow us to differentiate it, and no others specific mineral phases containing boron has been identified. Profile pattern by XRD analysis allowed us to identify four zones composing the degraded Portland cement paste

  6. THERMAL DEGRADATION OF THERMOTROPIC LIQUID CRYSTALLINE TERPOLYESTERS BASED ON VANILLIC ACID, p-HYDROXYBENZOIC ACID AND POLY(ETHYLENE TEREPHTHALATE)

    LI Xingui; HUANG Meirong; GUAN Guihe; SUN Tong

    1993-01-01

    Nine thermotropic liquid crystalline terpolyesters based on vanillic acid(V), p-hydroxybenzoic acid(H) and poly(ethylene terephthalate)(E) were investigated by thermogravimetry to ascertain their thermostability and the kinetic parameters for thermal degradation. Overall activation energy data of the degradation had been calculated over the range 5~70% weight loss. The temperatures and the activation energy of the degradation lie in the ranges of 384~394 ℃ at a heating rate of 1 ℃/min and 176~205 KJ/mol at the weight loss of 5%, respectively, which suggests that the terpolyesters have good thermostability.

  7. New Biocompatible Polyesters Derived from α-Amino Acids: Hydrolytic Degradation Behavior

    Jeoshua Katzhendler

    2010-10-01

    Full Text Available New polymers were synthesized from α-hydroxy acids derived from the natural amino acids Ile, Leu, Phe, and Val, combined with lactic acid, glycolic acid and 6-hydroxyhexanoic acid by direct condensation. The toxicity was determined and the degradation process of these polyesters was investigated under physiological conditions by analyzing the composition of the degraded polymers and the oligomers cleaved in the buffer medium. The polymers were found to be non toxic to two cell lines. Polymers displayed a biphasic degradation behavior. In most cases, a linear relationship was found between the weight loss constant and the hydrophobicity of the polymers, Log P. Regarding the second stage of weight loss, it is apparent that polymers derived from α-hydroxy(Lisoleucine ((LHOIle and α-hydroxy(LValine ((LHOVal degraded much faster than those derived from α-hydroxy(Lleucine ((LHOLeu and α-hydroxy(Lphenylalanine ((LHOPhe, probably due to different spatial orientation of the side chains. Copolymers of 6-hydroxyhexanoic acid displayed slow degradation rates as expected, whereas the degradation profile of copolymers of lactic acid was similar to the other homopolymers. These new polyesters may serve as potential biocompatible materials for medical applications.

  8. Malonic acid suppresses mucin-type O-glycan degradation during hydrazine treatment of glycoproteins.

    Goso, Yukinobu

    2016-03-01

    Hydrazine treatment is frequently used for releasing mucin-type O-glycans (O-glycans) from glycoproteins because the method provides O-glycans that retain a reducible GalNAc at their reducing end, which is available for fluorescent labeling. However, many O-glycans are degraded by "peeling" during this treatment. In the current study, it was found that malonic acid suppressed O-glycan degradation during hydrazine treatment of bovine fetuin or porcine gastric mucin in both the gas and liquid phases. This is paradoxical because the release of O-glycans from glycoproteins occurs under alkaline conditions. However, malonic acid seems to prevent the degradation through its acidic property given that other weak acids also prevented the degradation. Accordingly, disodium malonate did not suppress O-glycan degradation. Application of this method to rat gastric mucin demonstrated that the majority of the major O-glycans obtained in the presence of malonic acid were intact, whereas those obtained in the absence of malonic acid were degraded. These results suggest that hydrazine treatment in the presence of malonic acid would allow glycomic analysis of native mucin glycoproteins. PMID:26723492

  9. Protective effect of hop ß-acids on microbial degradation of thick juice during storage

    Justé, Annelies; Krause, M.S.; Lievens, Bart; Klingeberg, M; Michiels, Christiaan; Willems, Kris

    2008-01-01

    Storing sugar extracts as thick juice, a form of sucrose syrup, is common practice in the sugar industry. However, thick juice storage commonly faces problems due to microbial degradation. In this study the value of a commercial alkaline solution of hop β-acids (HBA) was assessed for prevention of microbial degradation of thick juice. The antimicrobial effect of different concentrations of HBA against juice degradation was tested in a pilot-scale thick juice storage experiment. Thick juice de...

  10. Identification of major degradation products of 5-aminosalicylic acid formed in aqueous solutions and in pharmaceuticals

    Jensen, J.; Cornett, Claus; Olsen, C. E.;

    1992-01-01

    The formation of four major degradation products of 5-aminosalicylic acid (5-ASA) in buffered solutions at pH 7.0 was demonstrated by gradient HPLC analysis. The isolation and structural elucidation of the resulting degradation products showed that the degradation of 5-ASA led to the formation of......-containing pharmaceuticals, which had not been stored as prescribed, but in diffuse daylight for up to 2 years....

  11. Draft Genome Sequence of Perfluorooctane Acid-Degrading Bacterium Pseudomonas parafulva YAB-1

    Yi, Langbo; Tang, Chongjian; Peng, Qingjing; Peng, Qingzhong; Chai, Liyuan

    2015-01-01

    Pseudomonas parafulva YAB-1, isolated from perfluorinated compound-contaminated soil, has the ability to degrade perfluorooctane acid (PFOA) compound. Here, we report the draft genome sequence and annotation of the PFOA-degrading bacterium P. parafulva YAB-1. The data provide the basis to investigate the molecular mechanism of PFOA metabolism.

  12. Draft Genome Sequence of Perfluorooctane Acid-Degrading Bacterium Pseudomonas parafulva YAB-1

    Tang, Chongjian; Peng, Qingjing; Peng, Qingzhong

    2015-01-01

    Pseudomonas parafulva YAB-1, isolated from perfluorinated compound-contaminated soil, has the ability to degrade perfluorooctane acid (PFOA) compound. Here, we report the draft genome sequence and annotation of the PFOA-degrading bacterium P. parafulva YAB-1. The data provide the basis to investigate the molecular mechanism of PFOA metabolism. PMID:26337877

  13. In situ ruminal degradation of phytic acid in formaldehyde treated rice bran

    Martin-Tereso, J.; Gonzalez, A.; Laar, van H.; Burbara, C.; Pedrosa, M.; Mulder, K.; Hartog, den L.A.; Verstegen, M.W.A.

    2009-01-01

    Rice bran has a very high content of phytic acid (IP6), which is a nutritional antagonist of Ca. Microbial phytase degrades IP6, but ruminal degradation of nutrients can be reduced by formaldehyde treatment. Milk fever in dairy cows can be prevented by reducing available dietary Ca to stimulate Ca h

  14. Performance Degradation Tests of Phosphoric Acid Doped PBI Membrane Based High Temperature PEM Fuel Cells

    Zhou, Fan; Araya, Samuel Simon; Grigoras, Ionela;

    2014-01-01

    Degradation tests of two phosphoric acid (PA) doped PBI membrane based HT-PEM fuel cells were reported in this paper to investigate the effects of start/stop and the presence of methanol in the fuel to the performance degradation. Continuous tests with H2 and simulated reformate which was composed...

  15. Identification of the primary mechanism for fungal lignin degradation. Progress report

    NONE

    1997-06-01

    Many lignin-degrading fungi appear to lack lignin peroxidase (LiP), an enzyme generally thought important for fungal ligninolysis. The authors are working with one of these fungi, Ceriporiopsis subvermispora, an aggressive white-rotter that selectively removes lignin from wood. During this project period, they have obtained the following principal results: new polymeric lignin model compounds were developed to assist in the elucidation of fungal ligninolytic mechanisms; experiments with one of the polymeric lignin models showed that C. subvermispora cultures which express no detectable LiP activity are nevertheless able to degrade nonphenolic lignin structures, this result is significant because LiPs were previously considered essential for fungal attack on these recalcitrant structures, which constitute about 90% of lignin; manganese peroxidases (MnPs), which C. subvermispora does produce, catalyze the peroxidation of unsaturated fatty acids to give fatty acid hydroperoxides, fatty acid hydroperoxides are also used by MnP as oxidants (in place of H{sub 2}O{sub 2}) that support the MnP catalytic cycle, these results indicate that MnP turnover in the presence of unsaturated lipids generates reactive lipid oxyradicals that could act as oxidant of other molecules; MnP-mediated lipid peroxidation results in the co-oxidative cleavage of nonphenolic lignin structures, the MnP/lipid peroxidation system may therefore provide C. subvermispora and other LiP-negative fungi with a mechanism to degrade the principal structures of lignin.

  16. Neutron scattering and HPLC study on L-ascorbic acid and its degradation

    The present paper shows a systematic dynamic and kinetic study on L-ascorbic acid and its degradation at high temperature. The neutron scattering study allows, through the behavior of quasi-elastic neutron scattering (QENS) spectra, to characterize the diffusive dynamics of L-ascorbic acid in water mixtures. Ascorbic acid undergoes degradation process at high temperature, but the presence of trehalose in solution markedly avoids ascorbic acid loss enhancing its t1/2 (half life time), as determined by high performance liquid chromatography (HPLC)

  17. Degradation of hydroxycinnamic acid mixtures in aqueous sucrose solutions by the Fenton process.

    Nguyen, Danny M T; Zhang, Zhanying; Doherty, William O S

    2015-02-11

    The degradation efficiencies and behaviors of caffeic acid (CaA), p-coumaric acid (pCoA), and ferulic acid (FeA) in aqueous sucrose solutions containing the mixture of these hydroxycinnamic acids (HCAs) were studied by the Fenton oxidation process. Central composite design and multiresponse surface methodology were used to evaluate and optimize the interactive effects of process parameters. Four quadratic polynomial models were developed for the degradation of each individual acid in the mixture and the total HCAs degraded. Sucrose was the most influential parameter that significantly affected the total amount of HCA degraded. Under the conditions studied there was a analysis showed goodness of fit between the experimental results and the predicted values. The degradation behavior of CaA differed from those of pCoA and FeA, where further CaA degradation is observed at increasing sucrose and decreasing solution pH. The differences (established using UV/vis and ATR-FTIR spectroscopy) were because, unlike the other acids, CaA formed a complex with Fe(III) or with Fe(III) hydrogen-bonded to sucrose and coprecipitated with lepidocrocite, an iron oxyhydroxide. PMID:25585639

  18. Recent progress of MODIS solar diffuser on-orbit degradation characterization

    Chen, H.; Wang, Z.; Sun, J.; Angal, A.; Xiong, X.

    2012-09-01

    An on-board Solar Diffuser (SD) is used for the MODIS reflective solar bands (RSB) calibration. Its on-orbit bidirectional reflectance factor (BRF) degradation is tracked using an on-board Solar Diffuser Stability Monitor (SDSM). The SDSM is a ratioing radiometer with nine detectors, covering wavelengths from 412 nm to 936 nm. During each scheduled SD calibration event, the SDSM makes alternate observations of the Sun and the sunlight reflected by the SD. To best match the SDSM detector signals from its Sun view and SD view, a fix attenuation screen is placed in its Sun view path. This paper provides a brief description of MODIS RSB on-orbit calibration and the use of its on-board SD and SDSM subsystem, including different approaches developed and used to track MODIS SD on-orbit degradation. It reports recent progress made to better characterize MODIS SD on-orbit degradation and to support MODIS Level 1B (L1B) calibration look-up table (LUT) updates for the upcoming collection 6 (C6) reprocessing. Results of both Terra and Aqua SD on-orbit degradation derived from newly improved SDSM Sun view screen vignetting function and response fitting strategy, and their impact on RSB calibration uncertainties are also presented.

  19. Dechlorination progress of chlorinated organic pollutants degraded by use of ionizing radiation in aqueous solutions

    Kinetics and mechanisms of dechlorination of chlorinated organic pollutants induced by ionizing radiation were described in this article. The progress on the dechlorination of chlorophenols, polychlorinated biphenyl, trichloroethylene, and perchloroethylene involved in radiolysis was also reviewed. In oxidative condition, hydroxyl radical (·OH) would attack chlorophenol to form ·OH-adducts, which could be dechlorinated gradually. However, chlorophenol can be directly reduced by hydrated electron (eaq-) to release Cl-. It was found that radiolytic degradation of polychlorinated biphenyls in organic solvent would release chlorine atoms gradually by chain reactions and the final products were Cl- and biphenyl. Trichloroethylene and tetrachloroethylene mainly reacted with ·OH with the final products of CO2, HCOOH and HCI. As conclusion, the reductive dechlorination of chlorinated organic pollutants possesses advantages of high degradation efficiency, simple products and relatively low radiation dose compared with the oxidation methods. (authors)

  20. Degradation of 2,4-dichlorophenoxyacetic acid in water by ozone-hydrogen peroxide process

    YU Ying-hui; MA Jun; HOU Yan-jun

    2006-01-01

    This study reports an investigation into the degradation of 2,4-dichlorophenoxyacetic acid in bubble contactor column by O3/H2O2 process, which is widely used as a principal advanced oxidation process. The degradation of 2,4-dichlorophenoxyacetic acid was studied under different H2O2/O3 molar ratio and pH value. Meanwhile, TOC removal was investigated both in distilled water and tap water. The influences of ozone transfer and consumed hydrogen peroxide were also discussed. The degradation products and oxidation intermediates were identified by GC-MS and LC-MS. A possible reaction mechanism was thus proposed.

  1. Recent progress in structural integrity assessment techniques for components subject to service-induced degradation

    Nuclear power plant components are exposed to a wide range of environmental and loading conditions which can cause degradation over time. Aging embrittlement, erosion-corrosion, irradiation embrittlement, stress corrosion cracking, and corrosion fatigue are examples of aging mechanisms which could reduce structural margins in reactor components. The degradation effects from these mechanisms have been seen more frequently with the aging of the early nuclear plants. Since there is a strong incentive for keeping these older plants running for longer periods of time without compromising safety, proper plant management to minimize damage from degradation mechanisms is extremely important. Structural margin assessment, monitoring, and maintenance are important elements of such a management plan. Significant progress has been recently made in the understanding, evaluation and monitoring of these degradation mechanisms. This has led also to new requirements in the ASME Code design basis for nuclear plants. Current state of understanding and new developments in the ASME Code to address some of these degradation mechanisms are covered in this paper. Cast stainless steels used in pump casings and valve bodies have been known to experience thermal aging embrittlement at reactor operating temperatures. Recent predictive models of thermal aging effects on material toughness, developed at Argonne National Lab are reviewed and applied to assess ASME Code structural margins of a reactor pump casing. A recent ASME Code Case provides methods for the evaluation and acceptance criteria for reactor pressure vessels having ductile fracture toughness values reduced below the requirements of 10CFR50 due to irradiation embrittlement. Background and application of this code case to an older BWR vessel is described. The occurrence of stress corrosion cracking in austenitic stainless steel piping highlighted the need for evaluation methods for structural margin assessment in piping

  2. Synthesis and Hydrolytic Degradation of Substituted Poly(DL-Lactic Acids

    Hideto Tsuji

    2011-08-01

    Full Text Available Non-substituted racemic poly(DL-lactic acid (PLA and substituted racemic poly(DL-lactic acids or poly(DL-2-hydroxyalkanoic acids with different side-chain lengths, i.e., poly(DL-2-hydroxybutanoic acid (PBA, poly(DL-2-hydroxyhexanoic acid (PHA, and poly(DL-2-hydroxydecanoic acid (PDA were synthesized by acid-catalyzed polycondensation of DL-lactic acid (LA, DL-2-hydroxybutanoic acid (BA, DL-2-hydroxyhexanoic acid (HA, and DL-2-hydroxydecanoic acid (DA, respectively. The hydrolytic degradation behavior was investigated in phosphate-buffered solution at 80 and 37 °C by gravimetry and gel permeation chromatography. It was found that the reactivity of monomers during polycondensation as monitored by the degree of polymerization (DP decreased in the following order: LA > DA > BA > HA. The hydrolytic degradation rate traced by DP and weight loss at 80 °C decreased in the following order: PLA > PDA > PHA > PBA and that monitored by DP at 37 °C decreased in the following order: PLA > PDA > PBA > PHA. LA and PLA had the highest reactivity during polymerization and hydrolytic degradation rate, respectively, and were followed by DA and PDA. BA, HA, PBA, and PHA had the lowest reactivity during polymerization and hydrolytic degradation rate. The findings of the present study strongly suggest that inter-chain interactions play a major role in the reactivity of non-substituted and substituted LA monomers and degradation rate of the non-substituted and substituted PLA, along with steric hindrance of the side chains as can be expected.

  3. Biosynthesis of highly unsaturated fatty acids by hydrocarbon degrading microorganisms

    MEHDI GHASEMI

    2015-04-01

    Full Text Available Disruption of polyunsaturated fatty acids (PUFA metabolism leads to many diseases. In this study, producers of γ-linolenic acid (GLA, arachidonic acid (ARA and eicosapentaenoic acid (EPA were selected: Cephalosporium humicola IE (on glucose, dry biomass – 14 g/l, total lipids – 18-20%, GLA in lipids – 12.0%, Mucor globosus 11 (respectively – 15 g/l, 18% and 5% and Pythium irregulare LX (on glucose, dry biomass – 14.5 g/l, total lipids – 18-20%, 9.2 and 7.8% of ARA and EPA, respectively. On crude oil as the only source of carbon, the amount of biomass of the specified fungi decreases by 3-4 times, whereas the quantity of lipids and highly unsaturated fatty acids increases in four and 1.2 - 3.4 times, respectively. The maximum γ-linolenic acid in M. globosus and C. humicola was detected at neutral рН. Optimum volume of inoculate was 2.0-4.0%, nitrogen source NH4NO3, a carbon-nitrogen ratio 34:1. For biosynthesis of ARA and EPA by P. irregulare, the optimum nitrogen source was NH4Cl, рН 7.0- 8.0 and С/N - 50:1 at 28°C. The process of adaptation to stressful situation under crude oil motivated the increase of the rate of membrane phospholipids with high quantity of unsaturated fatty acids.

  4. Production and degradation of oxalic acid by brown rot fungi

    Our results show that all of the brown rot fungi tested produce oxalic acid in liquid as well as in semisolid cultures. Gloeophyllum trabeum, which accumulates the lowest amount of oxalic acid during decay of pine holocellulose, showed the highest polysaccharide-depolymerizing activity. Semisolid cultures inoculated with this fungus rapidly converted 14C-labeled oxalic acid to CO2 during cellulose depolymerization. The other brown rot fungi also oxidized 14C-labeled oxalic acid, although less rapidly. In contrast, semisolid cultures inoculated with the white rot fungus Coriolus versicolor did not significantly catabolize the acid and did not depolymerize the holocellulose during decay. Semisolid cultures of G. trabeum amended with desferrioxamine, a specific iron-chelating agent, were unable to lower the degree of polymerization of cellulose or to oxidize 14C-labeled oxalic acid to the extent or at the rate that control cultures did. These results suggest that both iron and oxalic acid are involved in cellulose depolymerization by brown rot fungi

  5. Photocatalyzed Degradation of Dibutylphthalate with Goethite and Carboxylic Acids

    Hejda, S.; Bajt, O.; Krýsa, J.; Klusoň, Petr

    Prague: Orgit, 2014, s. 78. ISBN 978-80-02-02555-9. [International Congress of Chemical and Process Engineering /21./ - CHISA 2014 and Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction /17./ - PRES 2014. Prague (CZ), 23.08.2014-27.08.2014] Institutional support: RVO:67985858 Keywords : iron * photochemically enhanced reduction * photocatalyzed degradation Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  6. Less harmful acidic degradation of poly(lactic-co-glycolic acid) bone tissue engineering scaffolds through titania nanoparticle addition

    Liu, Huinan; Slamovich, Elliott B; Webster, Thomas J

    2006-01-01

    In the last 10 years, biodegradable aliphatic polyesters, such as poly(lactic-co-glycolic acid) (PLGA), have attracted increasing attention for their use as scaffold materials in bone tissue engineering because their degradation products can be removed by natural metabolic pathways. However, one main concern with the use of these specific polymers is that their degradation products reduce local pH, which in turn induces an inflammatory reaction and damages bone cell health at the implant site...

  7. Chloroacetic acids - Degradation intermediates of organic matter in forest soil

    Matucha, Miroslav; Gryndler, Milan; Schröder, P.; Forczek, Sándor; Uhlířová, H.; Fuksová, Květoslava; Rohlenová, Jana

    2007-01-01

    Roč. 39, č. 1 (2007), s. 382-385. ISSN 0038-0717 R&D Projects: GA ČR GA522/02/0874; GA ČR GA526/05/0636 Institutional research plan: CEZ:AV0Z50380511 Keywords : trichloroacetic acid * dichloroacetic acid * chlorination * soil organic matter Subject RIV: EF - Botanics Impact factor: 2.580, year: 2007

  8. Controlled Degradation and Mechanical Behavior of Photopolymerized Hyaluronic Acid Networks

    Burdick, Jason A.; CHUNG, CINDY; Jia, Xinqiao; Randolph, Mark A.; Langer, Robert

    2005-01-01

    Hyaluronic acid is a natural polysaccharide found abundantly throughout the body with many desirable properties for application as a biomaterial, including scaffolding for tissue engineering. In this work, hyaluronic acid with molecular weights ranging from 50 to 1100 kDa was modified with methacrylic anhydride and photopolymerized into networks with a wide range of physical properties. With macromer concentrations from 2 to 20 wt%, networks exhibited volumetric swelling ratios ranging from ~...

  9. Electrochemical assisted photocatalytic degradation of salicylic acid with highly ordered TiO2 nanotube electrodes

    To explore the kinetics of photoelectrocatalytic degradation of salicylic acid, one of the important PPCPs, highly ordered TiO2 nanotube arrays (NTs) were prepared by the electrochemical anodization and characterized with scanning electron microscopy and X-ray diffraction techniques. The effect of TiO2 NTs properties, bias potential, initial salicylic acid concentration and solution pH on the degradation efficiency was studied and carefully analyzed. The results revealed that the salicylic acid degradation follows quasi-first order kinetics in the photoelectrocatalytic process, and the fastest decay kinetics was achieved in acidic environment (pH 2). The result was further interpreted through the electrochemical impedance spectroscopy. It is confirmed that the electrochemical assisted photocatalysis is a synergetic approach to combat stable organic substances with improved efficiency.

  10. Solvent degradation and high sulphuric acid stripping in the Rabbit Lake uranium mill

    The Rabbit Lake uranium mill started processing Collins Bay B-Zone ore in 1985 using the conventional process of acid leaching/tertiary amine extraction followed by a new stripping method employing 400 g/L sulphuric acid as the stripping agent. By mid-1986 a large portion of the tertiary amine component of the solvent had degraded, producing a waxy gel which resulted in numerous operational problems and eventually required replacement of the solvent inventory. This paper describes several aspects of this problem including: i) plant experience; ii) identification of the degradation products as secondary amines complexed with sulphuric acid as both cationic and anionic complexes; and iii) testwork directed at the resolution of the solvent degradation problem. This latter program identified the key operational parameters which must be controlled to prevent a recurrence of the problem, thereby allowing for routine use of the high acid stripping process

  11. Early diagnostic of concurrent gear degradation processes progressing under time-varying loads

    Guilbault, Raynald; Lalonde, Sébastien

    2016-08-01

    This study develops a gear diagnostic procedure for the detection of multi- and concurrent degradation processes evolving under time-varying loads. Instead of a conventional comparison between a descriptor and an alarm level, this procedure bases its detection strategy on a descriptor evolution tracking; a lasting descriptor increase denotes the presence of ongoing degradation mechanisms. The procedure works from time domain residual signals prepared in the frequency domain, and accepts any gear conditions as reference signature. To extract the load fluctuation repercussions, the procedure integrates a scaling factor. The investigation first examines a simplification assuming a linear connection between the load and the dynamic response amplitudes. However, while generally valuable, the precision losses associated with large load variations may mask the contribution of tiny flaws. To better reflect the real non-linear relation, the paper reformulates the scaling factor; a power law with an exponent value of 0.85 produces noticeable improvements of the load effect extraction. To reduce the consequences of remaining oscillations, the procedure also includes a filtering phase. During the validation program, a synthetic wear progression assuming a commensurate relation between the wear depth and friction assured controlled evolutions of the surface degradation influence, whereas the fillet crack growth remained entirely determined by the operation conditions. Globally, the tested conditions attest that the final strategy provides accurate monitoring of coexisting isolated damages and general surface deterioration, and that its tracking-detection capacities are unaffected by severe time variations of external loads. The procedure promptly detects the presence of evolving abnormal phenomena. The tests show that the descriptor curve shapes virtually describe the constant wear progression superimposed on the crack length evolution. At the tooth fracture, the mean values of

  12. Characterization of bacterial diversity in an atrazine degrading enrichment culture and degradation of atrazine, cyanuric acid and biuret in industrial wastewater.

    Dutta, Anirban; Vasudevan, Venugopal; Nain, Lata; Singh, Neera

    2016-01-01

    An enrichment culture was used to study atrazine degradation in mineral salt medium (MSM) (T1), MSM+soil extract (1:1, v/v) (T2) and soil extract (T3). Results suggested that enrichment culture required soil extract to degrade atrazine, as after second sequential transfer only partial atrazine degradation was observed in T1 treatment while atrazine was completely degraded in T2 and T3 treatments even after fourth transfer. Culture independent polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) technique confirmed selective enrichment of genus Bacillus along with Pseudomonas and Burkholderia. Degradation of atrazine/metabolites in the industrial wastewater was studied at different initial concentrations of the contaminants [wastewater-water (v/v) ratio: T1, 1:9; T2, 2:8; T3, 3:7; T4, 5:5 and T5, undiluted effluent]. The initial concentrations of atrazine, cyanuric acid and biuret ranged between 5.32 and 53.92 µg mL(-1), 265.6 and 1805.2 µg mL(-1) and 1.85 and 16.12 µg mL(-1), respectively. The enrichment culture was able to completely degrade atrazine, cyanuric acid and biuret up to T4 treatment, while no appreciable degradation of contaminants was observed in the undiluted effluent (T5). Inability of enrichment culture to degrade atrazine/metabolites might be due to high concentrations of cyanuric acid. Therefore, a separate study on cyanuric acid degradation suggested: (i) no appreciable cyanuric acid degradation with accumulation of an unidentified metabolite in the medium where cyanuric acid was supplemented as the sole source of carbon and nitrogen; (ii) partial cyanuric acid degradation with accumulation of unidentified metabolite in the medium containing additional nitrogen source; and (iii) complete cyanuric acid degradation in the medium supplemented with an additional carbon source. This unidentified metabolite observed during cyanuric acid degradation and also detected in the enrichment culture inoculated wastewater samples

  13. The contribution of mediated oxidation mechanisms in the electrolytic degradation of cyanuric acid using diamond anodes.

    Bensalah, Nasr; Dbira, Sondos; Bedoui, Ahmed

    2016-07-01

    In this work, the contribution of mediated oxidation mechanisms in the electrolytic degradation of cyanuric acid using boron-doped diamond (BDD) anodes was investigated in different electrolytes. A complete mineralization of cyanuric acid was obtained in NaCl; however lower degrees of mineralization of 70% and 40% were obtained in Na2SO4 and NaClO4, respectively. This can be explained by the nature of the oxidants electrogenerated in each electrolyte. It is clear that the contribution of active chlorine (Cl2, HClO, ClO(-)) electrogenerated from oxidation of chlorides on BDD is much more important in the electrolytic degradation of cyanuric acid than the persulfate and hydroxyl radicals produced by electro-oxidation of sulfate and water on BDD anodes. This could be explained by the high affinity of active chlorine towards nitrogen compounds. No organic intermediates were detected during the electrolytic degradation of cyanuric acid in any the electrolytes, which can be explained by their immediate depletion by hydroxyl radicals produced on the BDD surface. Nitrates and ammonium were the final products of electrolytic degradation of cyanuric acid on BDD anodes in all electrolytes. In addition, small amounts of chloramines were formed in the chloride medium. Low current density (≤10mA/cm(2)) and neutral medium (pH in the range 6-9) should be used for high efficiency electrolytic degradation and negligible formation of hazardous chlorate and perchlorate. PMID:27372125

  14. Mechanism of azo dye degradation by ionizing radiation. Degradation of sulfanilic acid azochromotrop and its parent compounds in aqueous solution

    Complete text of publication follows. Mechanistic studies were made on ·OH radical and hydrated electron reaction with Sulfanilic Acid Azochromotrop (SPADNS) as model azo dye. SPADNS contains 4,5-dihydroxynaphtalene 2,7-disulfonic acid part and 4-sulfophenylazo group. To establish the details of the reaction mechanism the reactions of two simpler molecules without 4-sulfophenylazo part were also studied: one of them contained one (in position 4, II), the other two (in positions 4 and 5, III) -OH groups. ·OH radicals react with these molecules with radical addition to the naphthalene 2,7-disulfonic acid part. The adduct cyclohexadienyl type radical may decay in radical-radical reactions, or undergoes a (pH dependent) water elimination to naphthoxy radical, radical decay takes place on the ms timescale. ·OH radical addition on the azo bond in dyes has low importance. Degradation efficiencies are 0.6-0.8. The hydrated electron in the case of the two simpler molecules reacts with the rings, while in the case of dye with the azo bond. Electron scavenging is followed by protonation, this reaction in the case of II and III yields cyclohexadienyl, while with the dye hydrazo radical. The efficiency of degradation with II and III is 0.2-0.6, while for the dye it is close to 1.

  15. Modeling the degradation of Portland cement pastes by biogenic organic acids

    Reactive transport models can be used to assess the long-term performance of cement-based materials subjected to biodegradation. A bioleaching test (with Aspergillus niger fungi) applied to ordinary Portland cement pastes during 15 months is modeled with HYTEC. Modeling indicates that the biogenic organic acids (acetic, butyric, lactic and oxalic) strongly accelerate hydrate dissolution by acidic hydrolysis whilst their complexation of aluminum has an effect on the secondary gel stability only. The deepest degradation front corresponds to portlandite dissolution and decalcification of calcium silicate hydrates. A complex pattern of sulfate phases dissolution and precipitation takes place in an intermediate zone. The outermost degraded zone consists of alumina and silica gels. The modeling accurateness of calcium leaching, pH evolution and degradation thickness is consistently enhanced whilst considering increase of diffusivity in the degraded zones. Precipitation of calcium oxalate is predicted by modeling but was hindered in the bioleaching reactor.

  16. Regulation of protein degradation pathways by amino acids and insulin in skeletal muscle of neonatal pigs

    Suryawan, Agus; Davis, Teresa A.

    2014-01-01

    Background The rapid gain in lean mass in neonates requires greater rates of protein synthesis than degradation. We previously delineated the molecular mechanisms by which insulin and amino acids, especially leucine, modulate skeletal muscle protein synthesis and how this changes with development. In the current study, we identified mechanisms involved in protein degradation regulation. In experiment 1, 6- and 26-d-old pigs were studied during 1) euinsulinemic-euglycemic-euaminoacidemic, 2) e...

  17. Modelling of Core Degradation and Progression of Severe Accident by Using MELCOR Code

    After Fukushima Daiichi Nuclear Accident, every single nuclear-field organization in the world focused in the analysis and study of scenarios that leads to core damage and hydrogen releases, in this way the integrated code MELCOR is used by the Mexican Regulatory Body as a tool in the analysis of severe accident progression, core melting and degradation. Scenarios related to core melting could provide information that show important parameters such as: time to reach the core damage, time window for level recovery, etc. This information is useful in the analysis of progression for this kind of events. In this work, Mexican Regulatory Body presents two simulations for different scenarios: a) Station Blackout with no cooling water injection and b) Station Blackout with late cooling water injection. Those two scenarios enclose the response of the fuel under Severe Accident conditions (progression of melting, relocation, temperature profile), plots in this document are qualitative items that allow to analyze the behavior for fuel/core elements. (author)

  18. Degradation of trichloroethylene by hydrodechlorination using formic acid as hydrogen source over supported Pd catalysts.

    Yu, Xin; Wu, Ting; Yang, Xue-Jing; Xu, Jing; Auzam, Jordan; Semiat, Raphael; Han, Yi-Fan

    2016-03-15

    An advanced method for the degradation of trichloroethylene (TCE) over Pd/MCM-41 catalysts through a hydrogen-transfer was investigated. Formic acid (FA) was used instead of gaseous H2 as the hydrogen resource. As a model H-carrier compound, FA has proven to yield less by-products and second-hand pollution during the reaction. Several factors have been studied, including: the property of catalyst supports, Pd loading and size, temperature, initial concentrations of FA and TCE (potential impact on the reaction rates of TCE degradation), and FA decomposition. The intrinsic kinetics for TCE degradation were measured, while the apparent activation energies and the reaction orders with respect to TCE and FA were calculated through power law models. On the basis of kinetics, we assumed a plausible reaction pathway for TCE degradation in which the catalytic degradation of TCE is most likely the rate-determining step for this reaction. PMID:26685065

  19. Degradation and in Vitro Biocompatibility studies of Citric acid based polyesters

    J. Margaret Marie

    2014-09-01

    Full Text Available The suitability of a polymer for a particular application is dependent on its physical and chemical properties. The monomers used play a significant role in the synthesis of polymers for biomedical applications. In the present work two copolyesters, poly (1,12-dodecanediol citrate-co-1,12- dodecanediol sebacate (PP1; poly (1,12-dodecanediol citrate-co-1,12- dodecanediol itaconate (PP2 were synthesized by catalyst-free melt polyesterification using monomers - citric acid, sebacic acid, itaconic acid and 1,12-dodecanediol. The polymers exhibited mechanical and thermal properties that made them suitable candidates for degradation and biocompatibility studies. In the present work the degradation and in vitro biocompatibility studies were carried out. The degradation and biocompatibility data support the potential use of the elastomers in tissue engineering applications as well as other clinical procedures that may require a biodegradable elastomeric implant.

  20. Effects of ultrasonic processing on degradation of salvianolic acid B in aqueous solution.

    Guo, Y X; Zhang, L; Lu, L; Liu, E H; Shi, C Z

    2016-09-10

    To evaluate the stability of salvianolic acid B (Sal B) under ultrasound-assisted extraction in the pharmaceutical industry, degradation of Sal B under ultrasonic irradiation was investigated as the function of buffer concentration, pH, and temperature. With regard to Sal-B concentration, a first-order degradation process was determined, with 10% change in assay from its initial concentration as t90=4.81h, under maximum stability acidic conditions (pH 2.0) and at 25°C. The logkpH-pH profile described by specific acid-base catalysis and water molecules supported the experimental results. Liquid chromatography-mass spectrometry (LC-MS) analyses revealed 7 major degradation products whose structures were characterized by electrospray ionization/mass spectrometry. A primary degradation pathway involved cleavage of the ester bond and ring-opening of benzofuran in Sal B was proposed. The complete degradation pathway of Sal B was also proposed. Results showed that ultrasonic irradiation leads to degradation of Sal B in aqueous solution. PMID:27442887

  1. Microbial dynamics in anaerobic enrichment cultures degrading di-n-butyl phthalic acid ester

    Trably, Eric; Batstone, Damien J.; Christensen, Nina;

    2008-01-01

    enrichment cultures degrading phthalic acid esters under methanogenic conditions. A selection pressure was applied by adding DBP at 10 and 200 mg L(-1) in semi-continuous anaerobic reactors. The microbial dynamics were monitored using single strand conformation polymorphism (SSCP). While only limited abiotic...... microorganism described previously as an anaerobic benzaldehyde degrader. Within the archaeal community, there was a shift between two different species of the genus Methanosaeta sp., indicating a highly specific impact of DBP or degradation products on archaeal species. RNA-directed probes were designed from...

  2. 2,4-Dichlorophenoxyacetic acid-degrading bacteria contain mosaics of catabolic genes.

    Fulthorpe, R R; McGowan, C; Maltseva, O V; Holben, W E; Tiedje, J M

    1995-01-01

    DNA from 32 2,4-dichlorophenoxyacetic acid (2,4-D)-degrading bacteria from diverse locations was probed with the first three genes of the well-known 2,4-D degradation pathway found in Alcaligenes eutrophus JMP134(pJP4). The majority of strains did not show high levels of homology to the first three genes of the 2,4-D degradation pathway, tfdA, -B, and -C. Most strains showed combinations of tfdA-, B-, and C-like elements that exhibited various degrees of homology to the gene probes. Strains h...

  3. Adsorption and degradation of phenoxyalkanoic acid herbicides in soils: A review.

    Paszko, Tadeusz; Muszyński, Paweł; Materska, Małgorzata; Bojanowska, Monika; Kostecka, Małgorzata; Jackowska, Izabella

    2016-02-01

    The primary aim of the present review on phenoxyalkanoic acid herbicides-2-(2,4-dichlorophenoxy) acetic acid (2,4-D), 2-(4-chloro-2-methylphenoxy) acetic acid (MCPA), (2R)-2-(2,4-dichlorophenoxy) propanoic acid (dichlorprop-P), (2R)-2-(4-chloro-2-methylphenoxy) propanoic acid (mecoprop-P), 4-(2,4-dichlorophenoxy) butanoic acid (2,4-DB), and 4-(4-chloro-2-methylphenoxy) butanoic acid (MCPB)-was to compare the extent of their adsorption in soils and degradation rates to assess their potential for groundwater contamination. The authors found that adsorption decreased in the sequence of 2,4-DB > 2,4-D > MCPA > dichlorprop-P > mecoprop-P. Herbicides are predominantly adsorbed as anions-on organic matter and through a water-bridging mechanism with adsorbed Fe cations-and their neutral forms are adsorbed mainly on organic matter. Adsorption of anions of 2,4-D, MCPA, dichlorprop-P, and mecoprop-P is inversely correlated with their lipophilicity values, and modeling of adsorption of the compounds based on this relationship is possible. The predominant dissipation mechanism of herbicides in soils is bacterial degradation. The contribution of other mechanisms, such as degradation by fungi, photodegradation, or volatilization from soils, is much smaller. The rate of bacterial degradation decreased in the following order: 2,4-D > MCPA > mecoprop-P > dichlorprop-P. It was found that 2,4-D and MCPA have the lowest potential for leaching into groundwater and that mecoprop-P and dichlorprop-P have slightly higher potential. Because of limited data on adsorption and degradation of 2,4-DB and MCPB, estimation of their leaching potential was not possible. PMID:26292078

  4. Genome Sequence Analysis of the Naphthenic Acid Degrading and Metal Resistant Bacterium Cupriavidus gilardii CR3.

    Xiaoyu Wang

    Full Text Available Cupriavidus sp. are generally heavy metal tolerant bacteria with the ability to degrade a variety of aromatic hydrocarbon compounds, although the degradation pathways and substrate versatilities remain largely unknown. Here we studied the bacterium Cupriavidus gilardii strain CR3, which was isolated from a natural asphalt deposit, and which was shown to utilize naphthenic acids as a sole carbon source. Genome sequencing of C. gilardii CR3 was carried out to elucidate possible mechanisms for the naphthenic acid biodegradation. The genome of C. gilardii CR3 was composed of two circular chromosomes chr1 and chr2 of respectively 3,539,530 bp and 2,039,213 bp in size. The genome for strain CR3 encoded 4,502 putative protein-coding genes, 59 tRNA genes, and many other non-coding genes. Many genes were associated with xenobiotic biodegradation and metal resistance functions. Pathway prediction for degradation of cyclohexanecarboxylic acid, a representative naphthenic acid, suggested that naphthenic acid undergoes initial ring-cleavage, after which the ring fission products can be degraded via several plausible degradation pathways including a mechanism similar to that used for fatty acid oxidation. The final metabolic products of these pathways are unstable or volatile compounds that were not toxic to CR3. Strain CR3 was also shown to have tolerance to at least 10 heavy metals, which was mainly achieved by self-detoxification through ion efflux, metal-complexation and metal-reduction, and a powerful DNA self-repair mechanism. Our genomic analysis suggests that CR3 is well adapted to survive the harsh environment in natural asphalts containing naphthenic acids and high concentrations of heavy metals.

  5. Degradation of Tannic Acid Using TiO2 Nano tubes as Electro catalyst

    Structured TiO2 nano tubes were grown on 2 mm thick titanium sheet by anodization of titanium in ethylene glycol medium containing 0.025 M NaF. The morphology of TiO2 nano tubes (TNT) was characterized using field emission scanning electron microscope. The potential of TNT as anode and also as photo catalyst for the degradation of tannic acid was studied. The mineralization of tannic acid was measured in terms Total Organic Carbon (TOC). Only 50% of TOC could be removed by exposing the tannic acid solution to UV-radiation (photolysis), whereas it was improved to 70% by electro oxidation (EO) using TNT as anode. Maximum degradation of 83% was achieved when electro oxidation was conducted under the influence of UV-radiation (photo electrocatalytic process (PEC)). Among the electrolytes tried, Na2SO4 was observed to be very effective for the degradation of tannic acid. The kinetics of tannic acid degradation by photo electrocatalytic process was found to follow zero-order rate expression.

  6. The radiation-induced degradation of hyaluronic acid

    Free-radical-induced chain scission in hyaluronic acid in aqueous solution has been studied using pulse radiolysis. In the absence of oxygen (nitrous oxide-saturated solutions) the process of chain breakage was monitored by measuring changes in conductivity resulting from the release of condensed counter-ions (K+), originally located in the vicinity of the break. The rate of formation of breaks was found to be first order and was catalysed by acid and base. More than two independent reaction pathways are involved in the cleavage processes. In the presence of oxygen (N2O/O2), chain scission has been measured by pulse radiolysis monitoring changes in scattered light intensity as well as following conductivity changes. In oxygenated solutions, the kinetics of OH-radical-induced chain scission were found to contain a second-order component; the rate of breakage was base catalysed. Yield-dose plots for chain breaks (N2O/O2, pulse-irradiated), showed a marked dependence on pH. Steady-state radiolysis (N2O/O2) was used to determine G-values for oxygen consumption, carbon dioxide formation and peroxide formation. (author)

  7. LC/MS/MS identification of some folic acid degradation products after E-beam irradiation

    Folates belong to the B vitamin group based on the parental compound folic acid (FA). They are involved in important biochemical processes like DNA synthesis and repair. FA is composed of a pteridine ring, p-aminobenzoic acid and glutamate moieties. The human metabolism is not able to synthesize folates and therefore obtain them from diet. FA, a synthetic vitamin, is used as a food fortificant because of its low price, relative stability and increased bioavailability compared to natural folate forms. FA is known to be a sensitive compound easily degradable in aqueous solution by ultraviolet and visible light towards various by-products. Irradiation is a process for preservation of foods that uses accelerated electrons, gamma rays or X-rays. Irradiation is proposed for the treatment of various food products, eliminating or reducing pathogens and insects, increasing the storage time and replacing chemical fumigants. This study concerns the identification of degradation products of FA after E-beam irradiation. FA aqueous solutions were irradiated with a Van de Graaff electrons beam accelerator (2 MeV, 100 μA current, 20 cm scan width, dose rate about 2 kGy/s). Applied doses were between 0 (control) and 10.0 kGy. Absorbed doses were monitored with FWT 60.00 radiochromic dosimeters. - Highlights: ► We investigated the degradation of folic acid aqueous solution after electron beam treatment. ► Radiation doses over 5 kGy promote huge folic acid degradation and appearance of several degradation products. ► PCA, PABA and pABGA, already known folic acid degradation products, are formed due to E-beam treatment. ► Xanthopterin, a new radio-induced breakdown product, is formed after irradiation treatment.

  8. Degradation of Acid Cyanide Poison in Rubber Seed (Hevea brasiliensis after Treatment with Rice Husk Ash

    Dewi Fortuna

    2015-01-01

    Full Text Available Rubber seed (Hevea brasiliensis contains protein (17.41 % and non-essential amino acid cysteine (0.78 % and acid cyanide poison (186.00 mg/kg. The purpose of this research was to determine the effect of rice husk ash on degradation of acid cyanide in rubber seed. This research used Completely Randomized Design (CRD using treatment of rice husk ash concentration with 5 levels of treatments (45; 60; 75; 90; 105 % and 4 replications. The result showed nonsignificant differences (p>0.05 in degradation of acid cyanide level during aging and significant differences (p<0.05 during soaking. Rubber seed treated with 90% of rice husk ash during aging period contained cyanide 47.25 ppm and rubber seed treated with 60% of rice husk ash during soaking period contained cyanide 40.37 ppm.

  9. The radiation-induced degradation of hyaluronic acid

    Deeble, D. J.; Phillips, G. O.; Bothe, E.; Schuchmann, H.-P.; von Sonntag, C.

    Free-radical-induced chain scission in hyaluronic acid in aqueous solution has been studied using pulse radiolysis. In the absence of oxygen (nitrous oxide-saturated solutions) the process of chain breakage was monitored by measuring changes in conductivity resulting from the release of condensed counter-ions (K +), originally located in the vicinity of the break. The rate of formation of breaks was found to be first order and was catalysed by acid and base (overall half-lives at pH values of 4.8, 7 and 10.2 were 0.6, 1 and 0.1 ms). It would seem that more than two independent reaction pathways are involved in the cleavage processes. In the presence of oxygen (N 2O/O 2), chain scission has been measured by pulse radiolysis monitoring changes in scattered light intensity as well as following conductivity changes. In oxygenated solutions, the kinetics of OH-radical-induced chain scission were found to contain a second-order component; the rate of breakage was base catalysed. Yield-dose plots for chain breaks (N 2O/O 2, pulse-irradiated), showed a marked dependence on pH, with G-values (molecules/100 eV) of 0.7, 2.5 and 4.7 at pH values of 7, 9.7 and 10.4, respectively. Steady-state radiolysis (N 2O/O 2) was used to determine G-values for oxygen consumption [ G(-O 2) ≈ 6], carbon dioxide formation [ G(CO 2) = 0.8 in the absence of O 2 and 1.3 in its presence] and peroxide formation [ G(H 2O 2) ≈ 2; G(organic hydroperoxide) < 0.15].

  10. Biodegradation of dimethyl phthalate by Sphingomonas sp. isolated from phthalic-acid-degrading aerobic granules.

    Zeng, Ping; Moy, Benjamin Yan-Pui; Song, Yong-Hui; Tay, Joo-Hwa

    2008-10-01

    Phthalic acid esters (PAEs) contamination in water, air, and soil is one of the major environmental concerns in many countries. Besides the PAE biodegradation process, the PAE degrading bacteria have become one of the focuses of study. This study reports the successful isolation of one kind of indigenous bacterium PA-02 from phthalic acid (PA)-degrading aerobic granules. Based on its 16S ribosomal DNA sequence, isolate PA-02 was identified as Sphingomonas genus with 100% similarity to Sphingomonas sp. strain D84532. Strain PA-02 was a Gram-negative, rod-shaped bacterium with strong auto-aggregation ability. In particular, the strain PA-02 possessed PAE-degrading ability without acclimation. Results of growth tests showed that strain PA-02 could degrade dimethyl phthalate (DMP), dibutyl phthalate, and diethylhexyl phthalate. The specific degradation rates of DMP and PA were concentration-dependent with maximum values of 0.4 g-DMP g(-1) biomass h(-1) and 1.3 g-PA g(-1) biomass h(-1), respectively. Kinetic studies also revealed that PA-02 was robust under high concentrations of DMP and PA. Even when the PA concentration was increased to 1,000.0 mg l(-1), the specific PA degradation rate was about 0.25 g-PA g(-1) biomass h(-1). The corresponding value for DMP was 0.067 g-DMP g(-1) biomass h(-1) at 1,000 mg l(-1). PMID:18751698

  11. Degradation Kinetics of Xylose and Glucose in Hydrolysate Containing Dilute Sulfuric Acid

    亓伟; 张素平; 许庆利; 任铮伟; 颜涌捷

    2008-01-01

    In preparation of fuel alcohol from biomass as feedstock,hydrolysis with dilute acid as catalyst iS one way to produce fermentable saccharide,xylose and glucose.However,the acid is also the catalyst in degradation of xylose and glucose and the yield of sacchride is dependent on the kinetic behaviors of saccharide.The degradation kinetics of xylose and glucose in the hydrolysate Was investigated under the conventional process conditions of hydrogen ion concentration from O.05 to 0.2 mol/L and temperature from 150 to 200℃.With a numerical calculation method,the kinetic parameters Were estimated,and the activation energy of xylose and glucose in the degradation reaction was obtained.The kinetic equations correlating the effect of hydrogen ion concentration on the rate constants of degradation reaction were established.Comparison between the calculated results from the equations and experimental ones proved that the established kinetic model could satisfactorily predict the degradation behavior of xylose and glucose in the acidic hydrolysate.

  12. Long-Term Progressive Degradation of the Biological Capability of Titanium

    Hajime Minamikawa

    2016-02-01

    Full Text Available Titanium undergoes time-dependent degradation in biological capability, or “biological aging”. It is unknown whether the biological aging of titanium occurs beyond four weeks and whether age-related changes are definitely associated with surface hydrophilicity. We therefore measured multiple biological parameters of bone marrow-derived osteoblasts cultured on newly prepared, one-month-old, three-month-old, and six-month-old acid-etched titanium surfaces, as well as the hydrophilicity of these surfaces. New surfaces were superhydrophilic with a contact angle of ddH2O of 0°, whereas old surfaces were all hydrophobic with the contact angle of around 90°. Cell attachment, cell spread, cell density, and alkaline phosphatase activity were highest on new surfaces and decreased in a time-dependent manner. These decreases persisted and remained significant for most of the biological parameters up to six-months. While the number of attached cells was negatively correlated with hydrophilicity, the other measured parameters were not. The biological capability of titanium continues to degrade up to six months of aging, but these effects are not directly associated with time-dependent reductions in hydrophilicity. A full understanding of the biological aging will help guide regulatory improvements in implant device manufacturing and develop countermeasures against this phenomenon in order to improve clinical outcomes.

  13. Glutamic acid modified fenton system for degradation of BTEX contamination

    Yehia, Fatma Z.; Badawi, Abdelfatah M.; Mady, Amr H. [Department of Petrochemicals, Egyptian Petroleum Research Institute, Nasr City, Cairo (Egypt); Kandile, Nadia G. [Faculty of Women, Department of Chemistry, Ain Shams University, Heliopolis, Cairo (Egypt)

    2012-07-15

    The present study employed a modified Fenton system that aims to extend the optimum pH range towards neutral conditions for studying the oxidation of benzene, toluene, ethyl benzene, xylenes (BTEX) using glutamic acid (Glu) as an iron chelator. Addition of 20 mM Glu greatly enhanced the oxidation rate of BTEX in modified Fenton system at pH 5-7. A rapid mass destruction (>97% after 1 h) of BTEX as a water contaminant carried out in the presence of 500 mM H{sub 2}O{sub 2}, 10 mM Fe{sup 2+}, and 20 mM Glu at pH 5 could be shown. The efficiency of this modified Fenton's system for mass destruction of BTEX in contaminated water was measured to estimate the impact of the major process variables that include initial concentrations of soluble Fe, H{sub 2}O{sub 2}, Glu (as metal chelating agent), and reaction time. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Muscle protein degradation and amino acid metabolism during prolonged knee-extensor exercise in humans

    Van Hall, Gerrit; Saltin, B; Wagenmakers, A J

    1999-01-01

    The aim of this study was to investigate whether prolonged one-leg knee-extensor exercise enhances net protein degradation in muscle with a normal or low glycogen content. Net amino acid production, as a measure of net protein degradation, was estimated from leg exchange and from changes in the c...... and glutamate extracted in increased amounts from the blood during exercise, are used for the synthesis of glutamine and for tricarboxylic-acid cycle anaplerosis.......The aim of this study was to investigate whether prolonged one-leg knee-extensor exercise enhances net protein degradation in muscle with a normal or low glycogen content. Net amino acid production, as a measure of net protein degradation, was estimated from leg exchange and from changes in the...... concentrations of amino acids that are not metabolized in skeletal muscle. Experiments were performed at rest and during one-leg knee-extensor exercise in six subjects having one leg with a normal glycogen content and the other with a low glycogen content. Exercise was performed for 90 min at a workload of 60...

  15. Natural Formation and Degradation of Chloroacetic Acids and Volatile Organochlorines in Forest Soil

    Laturnus, F.; Fahimi, I.; Gryndler, Milan; Hartmann, A.; Heal, M. R.; Matucha, M.; Schöler, H. F.; Schroll, R.; Svensson, T.

    2005-01-01

    Roč. 12, č. 4 (2005), s. 233-244. ISSN 0944-1344 Institutional research plan: CEZ:AV0Z50200510 Keywords : chloroacetic acids * degradation * fores decline Subject RIV: EE - Microbiology, Virology Impact factor: 1.518, year: 2005

  16. Catalyst Degradation in High Temperature Proton Exchange Membrane Fuel Cells Based on Acid Doped Polybenzimidazole Membranes

    Cleemann, Lars Nilausen; Buazar, F.; Li, Qingfeng; Jensen, Jens Oluf; Pan, Chao; Steenberg, T.; Dai, S.; Bjerrum, Niels J.

    2013-01-01

    Degradation of carbon supported platinum catalysts is a major failure mode for the long term durability of high temperature proton exchange membrane fuel cells based on phosphoric acid doped polybenzimidazole membranes. With Vulcan carbon black as a reference, thermally treated carbon black and...

  17. Factors that affect the degradation of naphthenic acids in oil sands wastewater by indigenous microbial communities

    The acute toxicity of wastewater generated during the extraction of bitumen from oil sands is believed to be due to naphthenic acids (NAs). To determine the factors that affect the rate of degradation of representative NAs in microcosms containing wastewater and the acute toxicity of treated and untreated wastewater, the effects of temperature, dissolved oxygen concentration, and phosphate addition on the rate of 14CO2 release form two representative naphthenic acid substrates, (linear) U-14C-palmitic acid (PA) and (bicyclic) decahydro-2-naphthoic acid-8-14C (DHNA), were monitored. Tailings pond water (TPW) contained microorganisms well adapted to mineralizing both PA and DHNA:PA was degraded more quickly (10--15% in 4 weeks) compared to DHNA (2--4% in 8 weeks). On addition of phosphate, the rate of NA degradation increased up to twofold in the first 4 weeks, with a concurrent increase in the rate of oxygen consumption by oil sands TPW. The degradation rate then declined to levels equivalent to those measured in flasks without phosphate. The observed plateau was not due to phosphate limitation. Decreases in either the dissolved oxygen concentration or the temperature reduced the rate. Phosphate addition also significantly decreased the acute toxicity of TPW to fathead minnows. In contrast, Microtox reg-sign analyses showed no reduction in the toxicity of treated or untreated TPW after incubation for up to 8 weeks at 15 C

  18. Anaerobic degradation of benzene by enriched consortia with humic acids as terminal electron acceptors

    Highlights: → Enriched consortia were able to couple the anaerobic degradation of benzene to the reduction of humic acids. → Electron-equivalents derived from anaerobic benzene oxidation were highly recovered as reduced humic acids. → Several species from classes β-, δ- and γ-Proteobacteria were enriched during the anaerobic degradation of benzene. - Abstract: The anaerobic degradation of benzene coupled to the reduction of humic acids (HA) was demonstrated in two enriched consortia. Both inocula were able to oxidize benzene under strict anaerobic conditions when the humic model compound, anthraquinone-2,6-disulfonate (AQDS), was supplied as terminal electron acceptor. An enrichment culture originated from a contaminated soil was also able to oxidize benzene linked to the reduction of highly purified soil humic acids (HPSHA). In HPSHA-amended cultures, 9.3 μM of benzene were degraded, which corresponds to 279 ± 27 micro-electron equivalents (μEq) L-1, linked to the reduction of 619 ± 81 μEq L-1 of HPSHA. Neither anaerobic benzene oxidation nor reduction of HPSHA occurred in sterilized controls. Anaerobic benzene oxidation did not occur in soil incubations lacking HPSHA. Furthermore, negligible reduction of HPSHA occurred in the absence of benzene. The enrichment culture derived from this soil was dominated by two γ-Proteobacteria phylotypes. A benzene-degrading AQDS-reducing enrichment originated from a sediment sample showed the prevalence of different species from classes β-, δ- and γ-Proteobacteria. The present study provides clear quantitative demonstration of anaerobic degradation of benzene coupled to the reduction of HA.

  19. Anaerobic degradation of benzene by enriched consortia with humic acids as terminal electron acceptors

    Cervantes, Francisco J., E-mail: fjcervantes@ipicyt.edu.mx [Division de Ciencias Ambientales, Instituto Potosino de Investigacion Cientifica y Tecnologica (IPICyT), Camino a la Presa San Jose 2055, Col. Lomas 4a. Seccion, San Luis Potosi, SLP, 78216 Mexico (Mexico); Mancilla, Ana Rosa; Toro, E. Emilia Rios-del [Division de Ciencias Ambientales, Instituto Potosino de Investigacion Cientifica y Tecnologica (IPICyT), Camino a la Presa San Jose 2055, Col. Lomas 4a. Seccion, San Luis Potosi, SLP, 78216 Mexico (Mexico); Alpuche-Solis, Angel G.; Montoya-Lorenzana, Lilia [Division de Biologia Molecular, Instituto Potosino de Investigacion Cientifica y Tecnologica (IPICyT), Camino a la Presa San Jose 2055, Col. Lomas 4a. Seccion, San Luis Potosi, SLP, 78216 Mexico (Mexico)

    2011-11-15

    Highlights: {yields} Enriched consortia were able to couple the anaerobic degradation of benzene to the reduction of humic acids. {yields} Electron-equivalents derived from anaerobic benzene oxidation were highly recovered as reduced humic acids. {yields} Several species from classes {beta}-, {delta}- and {gamma}-Proteobacteria were enriched during the anaerobic degradation of benzene. - Abstract: The anaerobic degradation of benzene coupled to the reduction of humic acids (HA) was demonstrated in two enriched consortia. Both inocula were able to oxidize benzene under strict anaerobic conditions when the humic model compound, anthraquinone-2,6-disulfonate (AQDS), was supplied as terminal electron acceptor. An enrichment culture originated from a contaminated soil was also able to oxidize benzene linked to the reduction of highly purified soil humic acids (HPSHA). In HPSHA-amended cultures, 9.3 {mu}M of benzene were degraded, which corresponds to 279 {+-} 27 micro-electron equivalents ({mu}Eq) L{sup -1}, linked to the reduction of 619 {+-} 81 {mu}Eq L{sup -1} of HPSHA. Neither anaerobic benzene oxidation nor reduction of HPSHA occurred in sterilized controls. Anaerobic benzene oxidation did not occur in soil incubations lacking HPSHA. Furthermore, negligible reduction of HPSHA occurred in the absence of benzene. The enrichment culture derived from this soil was dominated by two {gamma}-Proteobacteria phylotypes. A benzene-degrading AQDS-reducing enrichment originated from a sediment sample showed the prevalence of different species from classes {beta}-, {delta}- and {gamma}-Proteobacteria. The present study provides clear quantitative demonstration of anaerobic degradation of benzene coupled to the reduction of HA.

  20. Photo catalytic degradation of phenolic acids in olive mills wastewater, Part 3

    Phenolic compounds are known to be present in high concentration in various of agro industrial wastes such as olive mill wastewater. As they are highly bio recalcitrant a possible treatment by advanced oxidation processes has to be investigated. The photo catalytic degradation of the phenolic acids p-Hydroxybenzoic acid, dihydroxybenzoic acid. gallic acid, vanillic acid, syringic acid) in the presence of TiO2 deposit on a glass plate has been reported. A comparison for the adsorption properties and the kinetics of reaction have been studied. The kinetics were found to be first order for all compounds and were compared with the compounds structures. the reaction rate for the compounds was found as the order Di-HBA2O2 was added. (Author)

  1. Degradation of Acid Cyanide Poison in Rubber Seed (Hevea brasiliensis) after Treatment with Rice Husk Ash

    Dewi Fortuna; Abdul Rahimsyah; Yuniwati Puspitasri

    2015-01-01

    Rubber seed (Hevea brasiliensis) contains protein (17.41 %) and non-essential amino acid cysteine (0.78 %) and acid cyanide poison (186.00 mg/kg). The purpose of this research was to determine the effect of rice husk ash on degradation of acid cyanide in rubber seed. This research used Completely Randomized Design (CRD) using treatment of rice husk ash concentration with 5 levels of treatments (45; 60; 75; 90; 105 %) and 4 replications. The result showed nonsignificant differences (p>0.05)...

  2. Phytic acid degradation by phytase – as viewed by 31P NMR and multivariate curve resolution

    Nielsen, Merete Møller; Viereck, Nanna; Engelsen, Søren Balling

    2007-01-01

    The 31P NMR method is a most direct and useful method to describe the degradation of phytic acid to lower inositol phosphates by the action of the enzyme phytase. The use of chemometric and CARS visualizes and helps in the interpretation of the results. By means of LatentiX it has been possible to visualize the time-dependent hydrolysis of phytic acid and by PCA the complexity of the phytic acid is shown in the score plots. By modeling the spectra in CARS it is possible to identify and quanti...

  3. Mass spectrometry of oil sands naphthenic acids : degradation in OSPW and wetland plants

    Headley, J. [Environment Canada, Saskatoon, SK (Canada). Water Science and Technology Directorate

    2009-07-01

    This presentation discussed mass spectrometry of oil sands naphthenic acids and the degradation in OSPW and wetland plants. It presented background information on the Athabasca oil sands and naphthenic acids which involve a mixture of alkanes and cycloalkane carboxylic acids with aliphatic side chains. The presentation also discussed mass spectrometry with electrospray operating in negative ion modes. Loop injection, external standard methods and solid phase extraction were reviewed along with improved analysis by removing background ions. Other topics that were presented included hydroponic test systems and wetland plant toxicity, growth and transpiration. It was concluded that dissipation included species containing oxygen, ozone, O{sub 4}, and O{sub 5}. tabs., figs.

  4. Degradation network reconstruction in uric acid and ammonium amendments in oil-degrading marine microcosms guided by metagenomic data

    Rafael eBargiela

    2015-11-01

    Full Text Available Biostimulation with different nitrogen sources is often regarded as a strategy of choice in combating oil spills in marine environments. Such environments are typically depleted in nitrogen, therefore limiting the balanced microbial utilization of carbon-rich petroleum constituents. It is fundamental, yet only scarcely accounted for, to analyse the catabolic consequences of application of biostimulants. Here, we examined such alterations in enrichment microcosms using sediments from chronically crude oil-contaminated marine sediment at Ancona harbor (Italy amended with natural fertilizer, uric acid (UA, or ammonium (AMM. We applied the web-based AromaDeg resource using as query Illumina HiSeq meta-sequences (UA: 27,893 open reading frames; AMM: 32,180 to identify potential catabolic differences. A total of 45 (for UA and 65 (AMM gene sequences encoding key catabolic enzymes matched AromaDeg, and their participation in aromatic degradation reactions could be unambiguously suggested. Genomic signatures for the degradation of aromatics such as 2-chlorobenzoate, indole-3-acetate, biphenyl, gentisate, quinoline and phenanthrene were common for both microcosms. However, those for the degradation of orcinol, ibuprofen, phenylpropionate, homoprotocatechuate and benzene (in UA and 4-aminobenzene-sulfonate, p-cumate, dibenzofuran and phthalate (in AMM, were selectively enriched. Experimental validation was conducted and good agreement with predictions was observed. This suggests certain discrepancies in action of these biostimulants on the genomic content of the initial microbial community for the catabolism of petroleum constituents or aromatics pollutants. In both cases, the emerging microbial communities were phylogenetically highly similar and were composed by very same proteobacterial families. However, examination of taxonomic assignments further revealed different catabolic pathway organization at the organismal level, which should be considered

  5. Degradation Network Reconstruction in Uric Acid and Ammonium Amendments in Oil-Degrading Marine Microcosms Guided by Metagenomic Data

    Bargiela, Rafael

    2015-11-24

    Biostimulation with different nitrogen sources is often regarded as a strategy of choice in combating oil spills in marine environments. Such environments are typically depleted in nitrogen, therefore limiting the balanced microbial utilization of carbon-rich petroleum constituents. It is fundamental, yet only scarcely accounted for, to analyze the catabolic consequences of application of biostimulants. Here, we examined such alterations in enrichment microcosms using sediments from chronically crude oil-contaminated marine sediment at Ancona harbor (Italy) amended with natural fertilizer, uric acid (UA), or ammonium (AMM). We applied the web-based AromaDeg resource using as query Illumina HiSeq meta-sequences (UA: 27,893 open reading frames; AMM: 32,180) to identify potential catabolic differences. A total of 45 (for UA) and 65 (AMM) gene sequences encoding key catabolic enzymes matched AromaDeg, and their participation in aromatic degradation reactions could be unambiguously suggested. Genomic signatures for the degradation of aromatics such as 2-chlorobenzoate, indole-3-acetate, biphenyl, gentisate, quinoline and phenanthrene were common for both microcosms. However, those for the degradation of orcinol, ibuprofen, phenylpropionate, homoprotocatechuate and benzene (in UA) and 4-aminobenzene-sulfonate, p-cumate, dibenzofuran and phthalate (in AMM), were selectively enriched. Experimental validation was conducted and good agreement with predictions was observed. This suggests certain discrepancies in action of these biostimulants on the genomic content of the initial microbial community for the catabolism of petroleum constituents or aromatics pollutants. In both cases, the emerging microbial communities were phylogenetically highly similar and were composed by very same proteobacterial families. However, examination of taxonomic assignments further revealed different catabolic pathway organization at the organismal level, which should be considered for designing

  6. Oxidation and degradation of short-chain aliphatic compounds by hyperazeotropic nitric acid

    To determine the ultimate fate of organic material present in nuclear fuel reprocessing solutions and the chemical nature of the last surviving residues, organic products of the hydrolysis/nitrolysis of tributyl phosphate were subjected to further degradation with boiling 20 M HNO3 (Iodox Process) and carbon balances were run. Except for methyl nitrate, nitrate esters were oxidized in refluxing 20 M HNO3, primarily to a mixture of carbon dioxide and the corresponding and shorter chain aliphatic acids. Typically, 40% or more of the carbon from the nitrate esters was converted to CO2. Except for formic acid, the straight-chain monobasic acids oxidized slowly. Compounds identified among those resulting from oxidation of butyric acid (e.g., from the oxidation of butyl nitrate) included succinic and oxalic acids, 3- and 4-hydroxy-butyric acids, nitrate esters of 3- and 4-hydroxybutyric acid, butyrolactone, and 3-nitrobutyric acid. The mechanisms for formation of these products are briefly discussed. Oxalic acid and the hydroxyaliphatic acids have some potential for complexing ceertain metallic fission products. These results show that traces of organic materials will always be present in actual fuel processing solutions unless special measures are taken to ensure their removal. This conclusion was reinforced by analysis of recycle acid from the Savannah River Plant. The possible implications to a reprocessing plant using 100% recycle are briefly discussed

  7. Microwave-assisted degradation of acid orange using a conjugated polymer, polyaniline, as catalyst

    Ufana Riaz

    2014-01-01

    Full Text Available Microwave-assisted photocatalytic degradation of dyes is one of the emerging technologies for waste water remediation. Microwave effectively accelerates photocatalytic degradation, when microwave electrodeless lamp (MEL substitutes traditional UV lamp as light source. This setup can be extremely simplified if MEL and photocatalyst can be replaced by a catalyst which can work under microwave irradiation in the absence of any light source. The present work reports for the first time degradation of acid orange 7 (AO under microwave irradiation using polyaniline (PANI as catalyst in the absence of any UV lamp as light source. The degradation/decolourization was carried out in neutral acidic and basic media and was monitored spectrophotometrically to evaluate the ability of microwave irradiation to degrade AO. Microwave irradiation showed excellent performance as it completely decolourizes AO dye solution in 10 min. With the advantages of low cost and rapid processing, this novel catalyst is expected to gain promising application in the treatment of various dyestuff wastewaters on a large scale.

  8. Influence of cellulose powder structure on moisture-induced degradation of acetylsalicylic acid.

    Mihranyan, A; Strømme, M; Ek, R

    2006-02-01

    The stability of crystalline acetylsalicylic acid (ASA) powder in binary mixtures with cellulose powders was investigated to reveal information about the influence of the cellulose structural properties on the moisture-induced ASA degradation. Different cellulose powder samples were manufactured and characterized by X-ray diffraction and N2 BET gas adsorption. The degradation patterns in ASA/cellulose mixtures were monitored as a function of salicylic acid increase versus time under various relative humidity conditions at 50 degrees C. The crystallinity index of cellulose samples varied between approximately 49 and 95%. The results indicated that cellulose powder with the lowest crystallinity index exhibited lower degradation rates than the samples with the higher crystallinity index. It should be noted that higher ASA degradation rates were observed in the samples with comparably lower moisture contents. This effect was most pronounced in the 1:3 (w/w), ASA/cellulose mixtures, whereas in 3:1 (w/w), ASA/cellulose mixtures the effect was less obvious. The findings emphasise the importance of cellulose structural organisation when governing the moisture's partition between cellulose and ASA during the hydrolytic degradation. PMID:16311024

  9. Influence of amino acids, buffers, and ph on the γ-irradiation-induced degradation of alginates.

    Ulset, Ann-Sissel T; Mori, Hideki; Dalheim, Marianne Ø; Hara, Masayuki; Christensen, Bjørn E

    2014-12-01

    Alginate-based biomaterials and medical devices are commonly subjected to γ-irradiation as a means of sterilization, either in the dry state or the gel (hydrated) state. In this process the alginate chains degrade randomly in a dose-dependent manner, altering alginates' material properties. The addition of free radical scavenging amino acids such as histidine and phenylalanine protects the alginate significantly against degradation, as shown by monitoring changes in the molecular weight distributions using SEC-MALLS and determining the pseudo first order rate constants of degradation. Tris buffer (0.5 M), but not acetate, citrate, or phosphate buffers had a similar effect on the degradation rate. Changes in pH itself had only marginal effects on the rate of alginate degradation and on the protective effect of amino acids. Contrary to previous reports, the chemical composition (M/G profile) of the alginates, including homopolymeric mannuronan, was unaltered following irradiation up to 10 kGy. PMID:25412478

  10. Studies on photo-electro-chemical catalytic degradation of acid scarlet 3R dye

    LI; Mingyu; XIONG; Lin; CHEN; Yunyun; ZHANG; Na; ZHANG; Yua

    2005-01-01

    A new type of photo-electro-chemical catalytic reactor was designed.Cathode and anode of the new reactor were made of high-purity graphite and titanium dioxide electrode respectively.A saturated calomel electrode (SCE) was used as the reference electrode.Under the condition of ultraviolet radiation and anodic bias-voltage, acid scarlet 3R was degraded by the process of photoelectrocatalysis with titanium dioxide electrode in anodic compartment, while it was degraded by electrogenerated Fenton's reagent and hydrogen peroxide through reducing dissolved oxygen with graphite electrode in catholyte.The new reactor made the best use of photogenerated holes and photogenerated charge on the anode of the new reactor, which achieved the purpose of degrading acid scarlet 3R in the cathodic and anodic compartments simultaneously, I.e."two electrodes and double effect".The experimental results showed that, compared with other photoelectrocatalysis reactors ("two electrodes and single effect" reactor), the new reactor has obviously enhanced the degradation of acid scarlet 3R dye.With the concentration of the dye being 30 mg·L-1 in water, under the operating conditions that when the inert supporting electrolyte concentration was 0.02 mol·L-1 sodium sulfate, initial solution pH=3, and cathodic potential -Ec=0.66 V, the highest decolorizing efficiency of 92% was accomplished in cathodic compartment,and that of 60% in anodic compartment.

  11. Evidence for Interspecies Gene Transfer in the Evolution of 2,4-Dichlorophenoxyacetic Acid Degraders

    McGowan, Catherine; Fulthorpe, Roberta; Wright, Alice; Tiedje, J M

    1998-01-01

    Small-subunit ribosomal DNA (SSU rDNA) from 20 phenotypically distinct strains of 2,4-dichlorophenoxyacetic acid (2,4-D)-degrading bacteria was partially sequenced, yielding 18 unique strains belonging to members of the alpha, beta, and gamma subgroups of the class Proteobacteria. To understand the origin of 2,4-D degradation in this diverse collection, the first gene in the 2,4-D pathway, tfdA, was sequenced. The sequences fell into three unique classes found in various members of the beta a...

  12. Ammonium-oxidizing bacteria facilitate aerobic degradation of sulfanilic acid in activated sludge.

    Chen, Gang; Ginige, Maneesha P; Kaksonen, Anna H; Cheng, Ka Yu

    2014-01-01

    Sulfanilic acid (SA) is a toxic sulfonated aromatic amine commonly found in anaerobically treated azo dye contaminated effluents. Aerobic acclimatization of SA-degrading mixed microbial culture could lead to co-enrichment of ammonium-oxidizing bacteria (AOB) because of the concomitant release of ammonium from SA oxidation. To what extent the co-enriched AOB would affect SA oxidation at various ammonium concentrations was unclear. Here, a series of batch kinetic experiments were conducted to evaluate the effect of AOB on aerobic SA degradation in an acclimatized activated sludge culture capable of oxidizing SA and ammonium simultaneously. To account for the effect of AOB on SA degradation, allylthiourea was used to inhibit AOB activity in the culture. The results indicated that specific SA degradation rate of the mixed culture was negatively correlated with the initial ammonium concentration (0-93 mM, R²= 0.99). The presence of AOB accelerated SA degradation by reducing the inhibitory effect of ammonium (≥ 10 mM). The Haldane substrate inhibition model was used to correlate substrate concentration (SA and ammonium) and oxygen uptake rate. This study revealed, for the first time, that AOB could facilitate SA degradation at high concentration of ammonium (≥ 10 mM) in an enriched activated sludge culture. PMID:25259503

  13. Scanning electron microscopic study of the hydrolytic degradation of poly(glycolic acid) suture

    This article reports the morphological observations on the surface changes of poly-(glycolic acid) sutures which have been exposed to various dosages of gamma irradiation (0, 2.5, 5.0, 10, 20 and 40 Mrad) and duration of immersion (0, 7, 14, 28, 48, 60, and 90 days) in a physiological saline buffer. The most important gross morphological characteristics of PGA suture hydrolytic degradation is the formation of surface cracks on the filaments. The regularity of the surface cracks increased with an increase in the gamma irradiation and the duration of hydrolysis. Surface cracks were not observed in irradiated sutures that had not been subjected to hydrolytic degradation. The arrangement of the surface cracks, their orientation on the filaments, and the direction of crack propagation provide very useful information for depicting the mechanism of hydrolytic degradation in this class of fibrous material. The microfibrillar model of fiber structure has been used as the basis for the proposed degradation mechanism of PGA in vitro. It is believed that hydrolysis occurs initially in the amorphous regions sandwiched between two crystalline zones, as tie-chain segments, free chain ends, and chain folds in these regions degrade into fragments. As degradation proceeds, the size of the fragments reaches the stage at which they can be dissolved into the buffer medium. This dissolution removes the fragments from the amorphous regions, and surface cracks appeared

  14. Degradation of fructans and production of propionic acid by Bacteroides thetaiotaomicron are enhanced by shortage of amino acids

    Signe eAdamberg

    2014-12-01

    Full Text Available Bacteroides thetaiotaomicron is commonly found in the human colon and stabilizes its ecosystem by the catabolism of various polysaccharides. A model of cross-talk between the metabolism of amino acids and fructans in B. thetaiotaomicron was proposed. The growth of B. thetaiotaomicron DSM 2079 in two defined media containing mineral salts and vitamins, and supplemented with either 20 or 2 amino acids, was studied in an isothermal microcalorimeter. The polyfructans inulin (from chicory and levan (synthesized using levansucrase from Pseudomonas syringae, two fructooligosaccharide preparations with different composition, sucrose and fructose were tested as substrates. The calorimetric power-time curves were substrate specific and typically multiauxic. A surplus of amino acids reduced the consumption of longer oligosaccharides (DP > 3. Bacterial growth was not detected either in the carbohydrate free medium containing amino acids or in the medium with inulin as a sole carbohydrate. In amino acid-restricted medium, fermentation leading to acetic acid formation was dominant at the beginning of growth (up to 24 h, followed by increased lactic acid production, and mainly propionic and succinic acids were produced at the end of fermentation. In the medium supplemented with 20 amino acids, the highest production of D-lactate (82 ± 33 mmol/gDW occurred in parallel with extensive consumption (up to 17 mmol/gDW of amino acids, especially Ser, Thr and Asp. The production of Ala and Glu was observed at growth on all substrates, and the production was enhanced under amino acid deficiency. The study revealed the influence of amino acids on fructan metabolism in B. thetaiotaomicron and showed that defined growth media are invaluable in elucidating quantitative metabolic profiles of the bacteria. Levan was shown to act as an easily degradable substrate for B. thetaiotaomicron. The effect of levan on balancing or modifying colon microbiota will be studied in

  15. Degradation of Fructans and Production of Propionic Acid by Bacteroides thetaiotaomicron are Enhanced by the Shortage of Amino Acids.

    Adamberg, Signe; Tomson, Katrin; Vija, Heiki; Puurand, Marju; Kabanova, Natalja; Visnapuu, Triinu; Jõgi, Eerik; Alamäe, Tiina; Adamberg, Kaarel

    2014-01-01

    Bacteroides thetaiotaomicron is commonly found in the human colon and stabilizes its ecosystem by catabolism of various polysaccharides. A model of cross-talk between the metabolism of amino acids and fructans in B. thetaiotaomicron was proposed. The growth of B. thetaiotaomicron DSM 2079 in two defined media containing mineral salts and vitamins, and supplemented with either 20 or 2 amino acids, was studied in an isothermal microcalorimeter. The polyfructans inulin (from chicory) and levan (synthesized using levansucrase from Pseudomonas syringae), two fructooligosaccharide preparations with different composition, sucrose and fructose were tested as substrates. The calorimetric power-time curves were substrate specific and typically multiauxic. A surplus of amino acids reduced the consumption of longer oligosaccharides (degree of polymerization > 3). Bacterial growth was not detected either in the carbohydrate free medium containing amino acids or in the medium with inulin as a sole carbohydrate. In amino acid-restricted medium, fermentation leading to acetic acid formation was dominant at the beginning of growth (up to 24 h), followed by increased lactic acid production, and mainly propionic and succinic acids were produced at the end of fermentation. In the medium supplemented with 20 amino acids, the highest production of d-lactate (82 ± 33 mmol/gDW) occurred in parallel with extensive consumption (up to 17 mmol/gDW) of amino acids, especially Ser, Thr, and Asp. The production of Ala and Glu was observed at growth on all substrates, and the production was enhanced under amino acid deficiency. The study revealed the influence of amino acids on fructan metabolism in B. thetaiotaomicron and showed that defined growth media are invaluable in elucidating quantitative metabolic profiles of the bacteria. Levan was shown to act as an easily degradable substrate for B. thetaiotaomicron. The effect of levan on balancing or modifying colon microbiota will

  16. Mechanism of Calcium Lactate Facilitating Phytic Acid Degradation in Soybean during Germination.

    Hui, Qianru; Yang, Runqiang; Shen, Chang; Zhou, Yulin; Gu, Zhenxin

    2016-07-13

    Calcium lactate facilitates the growth and phytic acid degradation of soybean sprouts, but the mechanism is unclear. In this study, calcium lactate (Ca) and calcium lactate with lanthanum chloride (Ca+La) were used to treat soybean sprouts to reveal the relevant mechanism. Results showed that the phytic acid content decreased and the availability of phosphorus increased under Ca treatment. This must be due to the enhancement of enzyme activity related to phytic acid degradation. In addition, the energy metabolism was accelerated by Ca treatment. The energy status and energy metabolism-associated enzyme activity also increased. However, the transmembrane transport of calcium was inhibited by La(3+) and concentrated in intercellular space or between the cell wall and cell membrane; thus, Ca+La treatment showed reverse results compared with those of Ca treatment. Interestingly, gene expression did not vary in accordance with their enzyme activity. These results demonstrated that calcium lactate increased the rate of phytic acid degradation by enhancing growth, phosphorus metabolism, and energy metabolism. PMID:27324823

  17. Abiotic Degradation Rates for Carbon Tetrachloride and Chloroform: Progress in FY 2010

    Amonette, James E.; Jeffers, Peter M.; Qafoku, Odeta; Russell, Colleen K.; Humphrys, Daniel R.; Wietsma, Thomas W.; Truex, Michael J.

    2010-12-08

    This report documents the progress made through FY 2010 on a project initiated in FY 2006 to help address uncertainties related to the rates of hydrolysis in groundwater at the Hanford Site for carbon tetrachloride (CT) and chloroform (CF). The study also explores the possible effects of contact with minerals and sediment (i.e., heterogeneous hydrolysis) on these rates. The research was initiated to decrease the uncertainties in abiotic degradation rates of CT and chloroform CF associated with temperature and possible heterogeneous effects. After 2 years of data collection, the first evidence for heterogeneous effects was identified for hydrolysis of CT, and preliminary evidence for the effects of different mineral types on CF hydrolysis rates also was reported. The CT data showed no difference among mineral types, whereas significant differences were seen in the CF results, perhaps due to the fact that CF hydrolyzes by both neutral and base-catalyzed mechanisms whereas CT follows only the neutral hydrolysis path. In this report, we review the project objectives, organization, and technical approaches taken, update the status and results of the hydrolysis-rate experiments after 4 years of experimentation (i.e., through FY 2010), and provide a brief discussion of how these results add to scientific understanding of the behavior of the CT/CF plume at the Hanford Site.

  18. Using gas chromatography/mass spectroscopy fingerprint analyses to document process and progress of oil degradation

    Roques, D.E.; Overton, E.B.; Henry, C.B. [Louisiana State Univ., Baton Rouge, LA (United States)

    1994-07-01

    One of the challenges in testing the effectiveness of bioremediation products is the lack of a standardized testing protocol. One requirement of any such evaluation is baseline and benchmark analyses of the oil and its degradation processes. The method described uses high resolution gas chromatography maw spectroscopy (GC/MS). This method has been adapted from oil fingerprinting techniques used by our group for oil spill response to major spills such as T/V Exxon Valdez and T/V Megaborg. It results in a high degree of chemical and spectral resolution from a single analysis that allows quantification of saturated hydrocarbons, polynuclear aromatic hydrocarbons (PAHs), sulfur heterocycles and selected biomarkers such as hopanes and steranes. High resolution GC/MS and compound specific analyses are a viable and efficient method of analyzing the extent and progress of oil bioremediation and that it should be possible to standardize the method for monitoring the biodegradation of oil. Data are also presented that show increased useful information obtained from this method and suggest possible future uses for this expanded database. 14 refs., 4 figs., 1 tab.

  19. Degraded Core Quench: Summary of Progress 1996-1999 - Executive Summary

    A status report on experiments and modelling relating to quench of degraded cores was issued by CSNI in August 1996, following the publication of the In-Vessel Core Degradation Code Validation Matrix. In response to a request by PWG2 through the TG-DCC, a review of progress since then to June 1999 has been performed. The scope is broadly the same as before, restricted to mainly rod-like geometries and not considering pure debris bed configurations. The scope has been increased slightly to include a VVER bundle quench experiment, CODEX-3, which falls within the parameter range of the Western bundle experiments performed to date. The same format has been adopted as before, with the experimental results for bundle and separate-effects tests being summarised in separate tables, updated from the earlier report. This review shows further evolutionary progress made in understanding the phenomena of fuel rod quench under severe accident conditions. The successful performance of commissioning and four main tests in the new bundle QUENCH facility at FZ Karlsruhe has provided valuable new data, supplemented by the VVER test CODEX-3 at AEKI Budapest. Temperature excursions and excess hydrogen production were only observed for quench from high temperature (2300 K) with a non pre-oxidised bundle (2 relevant tests); for quench from lower temperatures (1750-1870 K) and with pre-oxidation (50- 500 μm oxide) smooth cooling with no significant excess hydrogen production was observed (3 relevant tests). When cooling a non pre-oxidised bundle from 1870 K rapidly by steam, no significant excursion was observed (1 test). These new lower temperature bundle tests have usefully extended the parameter range down from that previously covered (quench temperature 2150 K and above, no pre-oxidation, temperature excursions/excess hydrogen production always observed), and have shown that there are conditions for quench from high temperature where excess temperatures and hydrogen production do not

  20. Cullin 3 mediates SRC-3 ubiquitination and degradation to control the retinoic acid response

    Ferry, Christine; Gaouar, Samia; Fischer, Benoit; Boeglin, Marcel; Paul, Nicodeme; Samarut, Eric; Piskunov, Aleksandr; Pankotai-Bodo, Gabriella; Brino, Laurent; Rochette-Egly, Cecile

    2011-01-01

    SRC-3 is an important coactivator of nuclear receptors including the retinoic acid (RA) receptor α. Most of SRC-3 functions are facilitated by changes in the posttranslational code of the protein that involves mainly phosphorylation and ubiquitination. We recently reported that SRC-3 is degraded by the proteasome in response to RA. Here, by using an RNAi E3-ubiquitin ligase entry screen, we identified CUL-3 and RBX1 as components of the E3 ubiquitin ligase involved in the RA-induced ubiquitination and subsequent degradation of SRC-3. We also show that the RA-induced ubiquitination of SRC-3 depends on its prior phosphorylation at serine 860 that promotes binding of the CUL-3–based E3 ligase in the nucleus. Finally, phosphorylation, ubiquitination, and degradation of SRC-3 cooperate to control the dynamics of transcription. In all, this process participates to the antiproliferative effect of RA. PMID:22147914

  1. Kinetics and Quantitative Structure—Activity Relationship Study on the Degradation Reaction from Perfluorooctanoic Acid to Trifluoroacetic Acid

    Chen Gong

    2014-08-01

    Full Text Available Investigation of the degradation kinetics of perfluorooctanoic acid (PFOA has been carried out to calculate rate constants of the main elementary reactions using the multichannel Rice-Ramsperger-Kassel-Marcus theory and canonical variational transition state theory with small-curvature tunneling correction over a temperature range of 200~500 K. The Arrhenius equations of rate constants of elementary reactions are fitted. The decarboxylation is role step in the degradation mechanism of PFOA. For the perfluorinated carboxylic acids from perfluorooctanoic acid to trifluoroacetic acid, the quantitative structure–activity relationship of the decarboxylation was analyzed with the genetic function approximation method and the structure–activity model was constructed. The main parameters governing rate constants of the decarboxylation reaction from the eight-carbon chain to the two-carbon chain were obtained. As the structure–activity model shows, the bond length and energy of C1–C2 (RC1–C2 and EC1–C2 are positively correlated to rate constants, while the volume (V, the energy difference between EHOMO and ELUMO (ΔE, and the net atomic charges on atom C2 (QC2 are negatively correlated.

  2. Photocatalytic degradation of commercially sourced naphthenic acids by TiO2-graphene composite nanomaterial.

    Liu, Juncheng; Wang, Lin; Tang, Jingchun; Ma, Jianli

    2016-04-01

    Naphthenic acids (NAs) are a major contributor to the toxicity in oil sands process-affected water (OSPW), which is produced by hot water extraction of bitumen. NAs are extremely difficult to be degraded due to its complex ring and side chain structure. Photocatalysis is recognized as a promising technology in the removal of refractory organic pollutants. In this work, TiO2-graphene (P25-GR) composites were synthesized by means of solvothermal method. The results showed that P25-GR composite exhibited better photocatalytic activity than pure P25. The removal efficiency of naphthenic acids in acid solution was higher than that in neutral and alkaline solutions. It was the first report ever known on the photodegradation of NAs based on graphene, and this process achieved a higher removal rate than other photocatalysis degradation of NAs in a shorter reaction time. LC/MS analysis showed that macromolecular NAs (carbon number 17-22, z value -2) were easy to be degraded than the micromolecular ones (carbon number 11-16, z value -2). Furthermore, the reactive oxygen species that play the main role in the photocatalysis system were studied. It was found that holes and ·OH were the main reactive species in the UV/P25-GR photocatalysis system. Given the high removal efficiency of refractory organic pollutants and the short degradation time, photodegradation based on composite catalysts has a broad and practical prospect. The study on the photodegradation of commercially sourced NAs may provide a guidance for the degradation of OSPW NAs by this method. PMID:26874061

  3. Transport and degradation of 2-14C abscicine acid in the coleus rehneltianus berger sprout

    1 μg ABA-2-14C aqueous solution was injected into the youngest or into a fully grown leaf of young and older coleus plants. The activity quantity in the various sprout parts is investigated after 2, 24 and 72 h; as well as which labelled substances other than abscisic acid (ABA) occur. The activity in the ethanol extracts was detected with the help of liquid scintillation measurements. Thin layer chromatography and gas chromatography were used to characterize the radioactive substances. The results show that ABA is degraded into three metabolites which are characterized by their relative Rsub(F) values using chromatography with LM 2 as substance 0.2, 0.5a, 0.5b and 0.8. Comparing with the literature shows that it could be 6'-hydroxy methyl ABA, ABA glucoside, phaseic acid and dihydrophaseic acid. Young and old leaves in older plants have the same ability to degrade ABA taking the occurence of the 0.8 metabolite as standard. The degradation in younger plants is firstly very slight. However, within 72 h the ability of ABA degradation is induced in older leaves of younger plants, so that finally the degradation rate is as big as in older plants. Activity is essentially exported by adult leaves of older plants. The basipetal transport is considerably greater than the acropetal one. Results show that mainly ABA is transported in the acropetal test, whereas ABA and fraction 0.5 are transported in the basipetal direction. A reversed transport direction is observed after applying ABA to a young leaf. The transport basipetal is polarized in the first two hours, after 72 hours of transport there is a definite acropetal polarity. (orig./MG)

  4. Nucleolytic degradation of homologous and heterologous deoxyribonucleic acid molecules at the surface of competent pneumococci

    Competent pneumococci can catalyze the rapid and quantitative degradation of extracellular deoxyribonucleic acid (DNA) molecules through the activity of surface-located nucleases (endo- and, possibly, exonucleases as well). Both homologous and heterologous DNAs are degraded by a mechanism that seems to involve a cyclic process: (i) attachment of DNA to the cell surface followed by (ii) nucleolytic attack, and (iii) release to the medium. Processes (ii) and (iii) are both inhibited by ethylenediaminetetraacetate. Whereas surface nuclease activity is specific for competent cells, the bulk of this activity is not coupled to irreversible DNA uptake (deoxyribonuclease-resistant binding). Pneumococcal DNA treated with ultraviolet irradiation or nitrous acid (cross-linking) is selectively impaired in the ability to irreversibly bind to competent cells, whereas reversible binding is normal. (U.S.)

  5. Oxalate-Degrading Capacities of Gastrointestinal Lactic Acid Bacteria and Urinary Tract Stone Formation

    Mohammad Kargar; Rouhi Afkari; Sadegh Ghorbani-Dalini

    2013-01-01

    Background: Calcium oxalate is one the most significant causes of human kidney stones. Increasing oxalate uptake results in increased urinary oxalate. Elevated urinary oxalate is one the most important causes of kidney stone formation. This study aims to evaluate oxalate-degrading capacity of lactic acid bacteria and its impact on incidence of kidney stone.Materials and Methods: This case-control study was conducted on serum, urinary, and fecal samples. The research population included a tota...

  6. Effects of Calcium Lignosulfonate and Silicic Acid on Ammonium Nitrate Degradation

    Ahmet Ozan Gezerman

    2014-01-01

    Full Text Available Ammonium nitrate salts are the most commonly used nitrogenous fertilizers in industry. However, storage of ammonium nitrate is problematic, since its initial properties can decline because of environmental factors, leading to large economic losses. In this study, in order to prevent the caking and degradation of ammonium nitrate, an alternative composition with additional calcium lignosulfonate and silicic acid was studied. The resulting fertilizer was analyzed by screening analysis, ion chromatography, and electron microscopy methods.

  7. Characterization of diverse 2,4-dichlorophenoxyacetic acid-degradative plasmids isolated from soil by complementation.

    Top, E. M.; Holben, W E; Forney, L J

    1995-01-01

    The diversity of 2,4-dichlorophenoxyacetic acid (2,4-D)-degradative plasmids in the microbial community of an agricultural soil was examined by complementation. This technique involved mixing a suitable Alcaligenes eutrophus (Rifr) recipient strain with the indigenous microbial populations extracted from soil. After incubation of this mixture, Rifr recipient strains which grow with 2,4-D as the only C source were selected. Two A. eutrophus strains were used as recipients: JMP228 (2,4-D-), whi...

  8. Degradation of acid red 14 by silver ion-catalyzed peroxydisulfate oxidation in an aqueous solution

    RASOULIFARD, Mohammad Hossein; MOHAMMADI, Seied Mohammad Mahdi DOUST

    2012-01-01

    Silver ion (Ag1+)-catalyzed peroxydisulfate was studied for the degradation of acid red 14 (AR-14) in an aqueous medium. The effect of different parameters, such as temperature, peroxydisulfate concentration, and dye and Ag1+ concentrations, were investigated. Application of Ag1+-catalyzed peroxydisulfate, as an advanced oxidation process, introduces an effectual method for wastewater treatment. An accelerated reaction using S2O82- to destroy dyes can be achieved via chemical activat...

  9. Hyaluronic Acid Hydrogels with Controlled Degradation Properties for Oriented Bone Regeneration

    J. Patterson; Siew, R; Herring, SW; Lin, ASP; Guldberg, R; Stayton, PS

    2010-01-01

    Non-healing fractures can result from trauma, disease, or age-related bone loss. While many treatments focus on restoring bone volume, few try to recapitulate bone organization. However, the native architecture of bone is optimized to provide its necessary mechanical properties. Hyaluronic acid (HA) hydrogel scaffold systems with tunable degradation properties were developed for the controlled delivery of osteoinductive and angiogenic growth factors, thus affecting the quantity and quality of...

  10. Studies of the Alkaline Degradation of Cellulose and the Isolation of Isosaccharinic Acids

    Shaw, Paul B.

    2013-01-01

    Cellulosic materials are expected to form a significant proportion of the waste proposed for disposal in underground repositories being designed for the storage of radioactive waste. Under the alkaline conditions of these facilities, cellulose degrades by a so called „peeling‟ reaction resulting in the production of a complex mixture of products (CDPs), the major components being α- and β isosaccharinic acid (α and β-ISA). A significant amount of research has been performed on ISA as part of ...

  11. Molecular assessment of complex microbial communities degrading long chain fatty acids in methanogenic bioreactors

    Sousa, D.Z.; Pereira, M.A.; Smidt, Hauke; Stams, A.J.M.; Alves, M. M.

    2007-01-01

    Microbial diversity of anaerobic sludge after extended contact with long chain fatty acids (LCFA) was studied using molecular approaches. Samples containing high amounts of accumulated LCFA were obtained after continuous loading of two bioreactors with oleate or with palmitate. These sludge samples were then incubated in batch assays to allow degradation of the biomass-associated LCFA. In addition, sludge used as inoculum for the reactors was also characterized. Predominant ...

  12. Microbial communities involved in anaerobic degradation of unsaturated or saturated long chain fatty acids

    Sousa, D.Z.; Pereira, M.A.; Stams, A.J.M.; Alves, M. M.; Smidt, H.

    2007-01-01

    Anaerobic long-chain fatty acid (LCFA)-degrading bacteria were identified by combining selective enrichment studies with molecular approaches. Two distinct enrichment cultures growing on unsaturated and saturated LCFAs were obtained by successive transfers in medium containing oleate and palmitate, respectively, as the sole carbon and energy sources. Changes in the microbial composition during enrichment were analyzed by denaturing gradient gel electrophoresis (DGGE) profiling of PCR...

  13. Phytase activity and degradation of phytic acid during rye bread making

    Nielsen, Merete Møller; Damstrup, Marianne Linde; Thomsen, Agnete Dal; Rasmussen, Søren Kjærgaard; Hansen, Åse

    2006-01-01

    Changes in phytic acid content, activity of phytase and α-amylase in rye breads were determined during rye bread making. The activity of phytase is highest in grain and flour whereas the activity in the sourdoughs is almost the half of the activity in the flour. The activity was unchanged in the dough after mixing and proofing. Degradation of phytic acid (IP6) into lower inositol-phosphates and free phosphate is almost completed during the production of rye bread with long fermentati...

  14. Performance Degradation Tests of Phosphoric Acid Doped Polybenzimidazole Membrane Based High Temperature Polymer Electrolyte Membrane Fuel Cells

    Zhou, Fan; Araya, Samuel Simon; Grigoras, Ionela;

    2015-01-01

    Degradation tests of two phosphoric acid (PA) doped PBI membrane based HT-PEM fuel cells were reported in this paper to investigate the effects of start/stop and the presence of methanol in the fuel to the performance degradation of the HT-PEM fuel cell. Continuous tests with pure dry H2 and meth......Degradation tests of two phosphoric acid (PA) doped PBI membrane based HT-PEM fuel cells were reported in this paper to investigate the effects of start/stop and the presence of methanol in the fuel to the performance degradation of the HT-PEM fuel cell. Continuous tests with pure dry H2...

  15. Impairment of cellulose- and cellobiose-degrading soil Bacteria by two acidic herbicides.

    Schellenberger, Stefanie; Drake, Harold L; Kolb, Steffen

    2012-02-01

    Herbicides have the potential to impair the metabolism of soil microorganisms. The current study addressed the toxic effect of bentazon and 4-chloro-2-methylphenoxyacetic acid on aerobic and anaerobic Bacteria that are involved in cellulose and cellobiose degradation in an agricultural soil. Aerobic saccharide degradation was reduced at concentrations of herbicides above environmental values. Microbial processes (e.g. fermentations, ferric iron reduction) that were linked to anaerobic cellulose and cellobiose degradation were reduced in the presence of both herbicides at concentrations above and at those that occur in crop field soil. 16S rRNA gene transcript numbers of total Bacteria, and selected bacterial taxa (Clostridia [Group I], Planctomycetaceae, and two uncultivated taxa of Bacteroidetes) decreased more in anoxic than in oxic cellulose-supplemented soil microcosms in the presence of both herbicides. Collectively, the results suggested that the metabolism of anaerobic cellulose-degrading Bacteria was impaired by typical in situ herbicide concentrations, whereas in situ concentrations did not impair metabolism of aerobic cellulose- and cellobiose-degrading soil Bacteria. PMID:22098368

  16. Influence of palm fatty acid distillate on rumen degradability and protozoa population in buffaloes

    Weber Vilas Boas Soares

    2010-11-01

    Full Text Available Oil and fat as energy sources at low cost are relevant in ruminant nutrition. The aim of this study was to evaluate the effects of palm fatty acid distillate (PFAD on the degradability and ciliate protozoa population in buffalo. Four rumen fistulated buffaloes were fed a basal diet in a Latin square (4x4 design trial. Treatments were designed with four of different levels of PFAD added directly into the rumen: 0; 200; 420 and 500 g/animal/d. High levels of PFAD (420 and 500 g/d promoted higher degradation of the soluble fraction and lower in potentially degradable fraction of dry matter (DM and neutral detergent fibre (NDF with lower values of potential and effective degradability in two evaluated grasses, bermudagrass and brachiariagrass. Significant decreases in the total number of protozoa/mL of rumen content, Entodinium and ciliates belonging to subfamily Diplodiniinae were observed at higher level of PFDA addition in the rumen. Also, Epidinium and Holotrich ciliates disappeared from the rumen. Significant correlations were observed of the ciliate concentration and composition as a function of dietary lipids content. Entodinium composition increased from 68.0% to 99.6% and Diplodiniinae reduced from 30.4% to 0.4% with increasing PFAD level indicating higher fat toxicity effect on the Diplodiniinae ciliates than Entodinium species and direct action of the larger ciliates on the fibre degradation.

  17. Influence of palm fatty acid distillate on rumen degradability and protozoa population in buffaloes

    Raul Franzolin

    Full Text Available Oil and fat as energy sources at low cost are relevant in ruminant nutrition. The aim of this study was to evaluate the effects of palm fatty acid distillate (PFAD on the degradability and ciliate protozoa population in buffalo. Four rumen fistulated buffaloes were fed a basal diet in a Latin square (4x4 design trial. Treatments were designed with four of different levels of PFAD added directly into the rumen: 0; 200; 420 and 500 g/animal/d. High levels of PFAD (420 and 500 g/d promoted higher degradation of the soluble fraction and lower in potentially degradable fraction of dry matter (DM and neutral detergent fibre (NDF with lower values of potential and effective degradability in two evaluated grasses, bermudagrass and brachiariagrass. Significant decreases in the total number of protozoa/mL of rumen content, Entodinium and ciliates belonging to subfamily Diplodiniinae were observed at higher level of PFDA addition in the rumen. Also, Epidinium and Holotrich ciliates disappeared from the rumen. Significant correlations were observed of the ciliate concentration and composition as a function of dietary lipids content. Entodinium composition increased from 68.0% to 99.6% and Diplodiniinae reduced from 30.4% to 0.4% with increasing PFAD level indicating higher fat toxicity effect on the Diplodiniinae ciliates than Entodinium species and direct action of the larger ciliates on the fibre degradation.

  18. From ether to acid: A plausible degradation pathway of glycerol dialkyl glycerol tetraethers

    Liu, Xiao-Lei; Birgel, Daniel; Elling, Felix J.; Sutton, Paul A.; Lipp, Julius S.; Zhu, Rong; Zhang, Chuanlun; Könneke, Martin; Peckmann, Jörn; Rowland, Steven J.; Summons, Roger E.; Hinrichs, Kai-Uwe

    2016-06-01

    Glycerol dialkyl glycerol tetraethers (GDGTs) are ubiquitous microbial lipids with extensive demonstrated and potential roles as paleoenvironmental proxies. Despite the great attention they receive, comparatively little is known regarding their diagenetic fate. Putative degradation products of GDGTs, identified as hydroxyl and carboxyl derivatives, were detected in lipid extracts of marine sediment, seep carbonate, hot spring sediment and cells of the marine thaumarchaeon Nitrosopumilus maritimus. The distribution of GDGT degradation products in environmental samples suggests that both biotic and abiotic processes act as sinks for GDGTs. More than a hundred newly recognized degradation products afford a view of the stepwise degradation of GDGT via (1) ether bond hydrolysis yielding hydroxyl isoprenoids, namely, GDGTol (glycerol dialkyl glycerol triether alcohol), GMGD (glycerol monobiphytanyl glycerol diether), GDD (glycerol dibiphytanol diether), GMM (glycerol monobiphytanol monoether) and bpdiol (biphytanic diol); (2) oxidation of isoprenoidal alcohols into corresponding carboxyl derivatives and (3) chain shortening to yield C39 and smaller isoprenoids. This plausible GDGT degradation pathway from glycerol ethers to isoprenoidal fatty acids provides the link to commonly detected head-to-head linked long chain isoprenoidal hydrocarbons in petroleum and sediment samples. The problematic C80 to C82 tetraacids that cause naphthenate deposits in some oil production facilities can be generated from H-shaped glycerol monoalkyl glycerol tetraethers (GMGTs) following the same process, as indicated by the distribution of related derivatives in hydrothermally influenced sediments.

  19. Catalytic Potential of Nano-Magnesium Oxide on Degradation of Humic Acids From Aquatic Solutions

    Ghorban Asgari

    2014-12-01

    Full Text Available Catalytic ozonation is a new and promising process used to remove the contaminants from drinking water and wastewater. This study aimed to evaluate the catalytic potential of nano-magnesium oxide (nano-MgO for the removal of humic acids (HA from water. Mg (NO32 solution was used to prepare MgO powder by the calcination method. In a semi-batch reactor, the catalytic ozonation was carried out. The effects of the various operating parameters, including pH, reaction time, T-butyl alcohol (TBA and phosphate on HA degradation were evaluated. Experimental results indicated that degradation of HA was increased as the pH solution and reaction time were increased. Maximum HA degradation was obtained at pH = 10 and the reaction time of 10 minutes in the catalytic process. The calculated catalytic potential of nano-MgO on ozonation of HA was 60%. Moreover, catalytic ozonation process was not affected by TBA and the main reaction on HA degradation HA have effect take place on MgO surface. According to the results of this study, the developed MgO catalyst is the active and proficient catalyst in HA degradation using the catalytic ozonation process.

  20. Oxidative degradation of salicylic acid by sprayed WO{sub 3} photocatalyst

    Mohite, S.V.; Rajpure, K.Y., E-mail: rajpure@yahoo.com

    2015-10-15

    Highlights: • The photoactivity of sprayed WO{sub 3} thin film. • Photoelectrocatalytic degradation of salicylic acid. • Reaction kinetics and mineralization of pollutants by COD. - Abstract: The WO{sub 3} thin films were deposited using spray pyrolysis technique. The prepared WO{sub 3} thin films were characterized using photoelectrochemical (PEC), X-ray diffraction, atomic force microscopy (AFM), and UV–vis absorbance spectroscopy techniques. PEC measurements of WO{sub 3} films deposited at different deposition temperatures were carried out to study photoresponse. The maximum photocurrent (I{sub ph} = 261 μA/cm{sup 2}) was observed for the film deposited at the 225 °C. The monoclinic crystal structure of WO{sub 3} has been confirmed from X-ray diffraction studies. AFM studies were used to calculate particle size and average roughness of the films. Optical absorbance was studied to estimate the bandgap energy of WO{sub 3} thin film which was about 2.65 eV. The photoelectrocatalytic activity of WO{sub 3} film was studied by degradation of salicylic acid with reducing concentrations as function of reaction time. The WO{sub 3} photocatalyst degraded salicylic acid to about 67.14% with significant reduction in chemical oxygen demand (COD) value.

  1. Free fatty acids degradation in grease trap purification using ozone bubbling and sonication

    Piotr Kwiatkowski, Michal; Satoh, Saburoh; Fukuda, Shogo; Yamabe, Chobei; Ihara, Satoshi; Nieda, Masanori

    2013-02-01

    The oil and fat were treated at first by only ozone bubbling and it was confirmed that the collection efficiency of them became 98.4% when the aeration was used. It showed that the aeration method in a grease trap cleared the standard value of 90% and there was no worry on the oil and fat outflow from a grease trap. The characteristics of sonication process were studied for free fatty acids degradation. The free saturated fatty acids are the most hard-degradable compounds of the fats, oils and greases (FOGs) in the grease trap. The influence of various parameters such as immersion level of an ultrasound probe in the liquid and bubbling of various gases (Ar, O2, air, O3) on the sonochemical and energy efficiency of the sonication process was investigated. The most effective degradation treatment method for saturated free fatty acids was the combination of sonication and low flow rate argon bubbling. Contribution to the Topical Issue "13th International Symposium on High Pressure Low Temperature Plasma Chemistry (Hakone XIII)", Edited by Nicolas Gherardi, Henryca Danuta Stryczewska and Yvan Ségui.

  2. Hydrothermal synthesis spherical TiO2 and its photo-degradation property on salicylic acid

    Anatase TiO2 spheres have been prepared using hydrothermal synthesis. The prepared spheres were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and UV-vis diffuse reflectance spectra (UV-vis DRS). The TiO2 consisted of well-defined spheres with size of 3-5 μm. The photocatalytic activity of spherical TiO2 was determined by degradation of salicylic acid under visible light irradiation. It was revealed that the degradation rate of the spherical TiO2 which was processed at 150 °C for 48 h could reach 81.758%. And the kinetics of photocatalytic degradation obeyed first-order kinetic, which the rate constant value was 0.01716 S-1 of the salicylic acid onto TiO2 (temperature: 150, time: 48 h). The kinetics of adsorption followed the pseudo-second-order model and the rate constant was 1.2695 g mg-1 of the salicylic acid onto TiO2 (temperature: 150, time: 48 h).

  3. Degradation and miscibility of poly(DL-lactic acid)/poly(glycolic acid) composite films: Effect of poly(DL-lactic-co-glycolic acid)

    Zhigang Ma; Na Zhao; Chengdong Xiong

    2012-08-01

    The in vitro degradation behaviour of poly(glycolic acid) (PGA) and its composite films containing poly(DL-lactic acid) (PDLLA) and poly(DL-lactic-co-glycolic acid) (PDLGA) were investigated via mass loss, scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). All the films were prepared by solution casting, using 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) as the solvent. Since the degradation rate of PDLLA is lower than that of PGA, those of the PDLLA/PGA composite films decreased. As a compatibilizer, PDLGA improved the compatibility and hydrolytic stability of PDLLA/PGA composite films. Changes in the composite films indicate that this kind of PGA-based composite biomaterial may be applicable to device design for clinical application in the future.

  4. Intestinal involvement in progressive systemic sclerosis detected by increased unconjugated serum bile acids.

    Stellaard, F.; Sauerbruch, T; Luderschmidt, C H; Leisner, B.; Paumgartner, G

    1987-01-01

    In patients with progressive systemic sclerosis, impaired motor function of the small intestine may lead to bacterial overgrowth causing diarrhoea, steatorrhoea and malabsorption. As unconjugated serum bile acids have been proposed as markers for small bowel bacterial overgrowth, we studied individual unconjugated serum bile acids in 36 patients with progressive systemic sclerosis. These patients had significantly higher serum concentrations of unconjugated cholic acid (median 0.18; range 0.0...

  5. Degradation of the herbicide 2, 4-dichlorophenoxyacetic acid (2,4-D) dimethylamine salt by gamma radiation from cobalt-60 in aqueous solution containing humic acid

    In this study, gamma radiation from cobalt-60 was used to degrade the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) dimethylamine salt in water in the presence of humic acid. The 2,4-D dimethylamine salt 1.13x10-4 mol dm-3 solution was irradiated with different doses. HPLC was used as an analytical technique to determine the degradation rate of herbicide studied. The results showed that the herbicide was completely degraded at an absorbed dose of 3 kGy. Degradation decreased when humic acid was added to all the doses. ESI/MS and MS/MS were used to identify the radiolytic degradation products. A fragmentation path for production of 4.6-dichlororesorcinol, is suggested. The radiolytic yields (G) were calculated

  6. Tyrosol degradation via the homogentisic acid pathway in a newly isolated Halomonas strain from olive processing effluents

    Liebgott, Pierre-Pol; Labat, Marc; Amouric, Agnès; Tholozan, Jean-Luc; LORQUIN, Jean

    2008-01-01

    To isolate a new Halomonas sp. strain capable of degrading tyrosol, a toxic compound present in olive mill wastewater, through the homogentisic acid (HGA) pathway. A moderately halophilic Gram-negative bacterium belonging to the Halomonas genus and designated strain TYRC17 was isolated from olive processing effluents. This strain was able to completely degrade tyrosol (2-(p-hydroxyphenyl)-ethanol), a toxic compound found in such effluent. Tyrosol degradation begins by an oxidation to 4-hydrox...

  7. Co-metabolic formation of substituted phenylacetic acids by styrene-degrading bacteria

    Michel Oelschlägel

    2015-06-01

    The styrene-degrading strains Rhodococcus opacus 1CP, Pseudomonas fluorescens ST, and the novel isolates Sphingopyxis sp. Kp5.2 and Gordonia sp. CWB2 were investigated with respect to their applicability to co-metabolically produce substituted phenylacetic acids. Isolates were found to differ significantly in substrate tolerance and biotransformation yields. Especially, P. fluorescens ST was identified as a promising candidate for the production of several phenylacetic acids. The biotransformation of 4-chlorostyrene with cells of strain ST was shown to be stable over a period of more than 200 days and yielded about 38 mmolproduct gcelldryweight−1 after nearly 350 days. Moreover, 4-chloro-α-methylstyrene was predominantly converted to the (S-enantiomer of the acid with 40% enantiomeric excess.

  8. The effect of sorption on the degradation of aromatic acids and bases

    Ainsworth, C.C.; Fredrickson, J.K.; Smith, S.C.

    1992-10-01

    The availability and degradation of selected ionizable organic compounds sorbed to pure mineral phases are discussed. Substrates sorbed to mineral surfaces may or may not be protected from microbial attack; the degree of protection appears to be dependent on the type and cell density of the microorganism involved. The currently available data, however, demonstrate that there is little, if any, consensus on the types of reactions or interactions that facilitate sorbed substrate utilization. Rates of degradation of organic bases and cations that sorb to clay minerals via an exchange reaction are suggested to be directly related to substrate binding intensity and conformation on the clay surface. Similarly, rates of degradation of organic acids sorbed to the surface of oxides are suggested to be related to their interaction with the surface and the type of oxide sorbent. Although the rate-limiting step in microbial utilization of sorbed acids and bases is apparently a desorption process, the rate of desorption is itself linked to the compound's binding intensities on a given sorbent. Thus, as the binding intensities of compounds increase, chemical kinetic reactions, rather than mass-transfer processes, appear to limit the rate of desorption.

  9. The effect of sorption on the degradation of aromatic acids and bases

    Ainsworth, C.C.; Fredrickson, J.K.; Smith, S.C.

    1992-10-01

    The availability and degradation of selected ionizable organic compounds sorbed to pure mineral phases are discussed. Substrates sorbed to mineral surfaces may or may not be protected from microbial attack; the degree of protection appears to be dependent on the type and cell density of the microorganism involved. The currently available data, however, demonstrate that there is little, if any, consensus on the types of reactions or interactions that facilitate sorbed substrate utilization. Rates of degradation of organic bases and cations that sorb to clay minerals via an exchange reaction are suggested to be directly related to substrate binding intensity and conformation on the clay surface. Similarly, rates of degradation of organic acids sorbed to the surface of oxides are suggested to be related to their interaction with the surface and the type of oxide sorbent. Although the rate-limiting step in microbial utilization of sorbed acids and bases is apparently a desorption process, the rate of desorption is itself linked to the compound`s binding intensities on a given sorbent. Thus, as the binding intensities of compounds increase, chemical kinetic reactions, rather than mass-transfer processes, appear to limit the rate of desorption.

  10. Degradation of Acid Orange 7 in an Atmospheric-Pressure Plasma-Solution System (Gliding Discharge)

    NI, Mingjiang; YANG, Huan; CHEN, Tong; ZHANG, Hao; WU, Angjian; DU, Changming; LI, Xiaodong

    2015-03-01

    In this work, a plasma-solution system was applied to the degradation of Acid Orange 7 (AO7). The effects of initial concentration and type of feed gases (air, oxygen, nitrogen or argon) were studied. As the initial concentration increased from 100 mg/L to 160 mg/L, the discolouration rate of AO7 decreased from 99.3% to 95.9%, whereas the COD removal rate decreased from 37.9% to 22.6%. Air provided the best discolouration and COD removal rates (99.3% and 37.9%, respectively). In the presence of a zero-valent iron (ZVI) catalyst, the AO7 COD removal rate increased to 76.4%. The degradation products were analysed by a GC-MS, revealing that the degradation of the dye molecule was initiated through the cleavage of the -N=N- bond before finally being converted to organic acids. supported by National Natural Science Foundation of China (Nos. 50908237, 51076142) and the Open Foundation of the State Key Laboratory of Clean Energy Utilization of China (No. ZJUCEU2009008)

  11. Oxalate-Degrading Capacities of Gastrointestinal Lactic Acid Bacteria and Urinary Tract Stone Formation

    Mohammad Kargar

    2013-10-01

    Full Text Available Background: Calcium oxalate is one the most significant causes of human kidney stones. Increasing oxalate uptake results in increased urinary oxalate. Elevated urinary oxalate is one the most important causes of kidney stone formation. This study aims to evaluate oxalate-degrading capacity of lactic acid bacteria and its impact on incidence of kidney stone.Materials and Methods: This case-control study was conducted on serum, urinary, and fecal samples. The research population included a total of 200 subjects divided in two equal groups. They were selected from the patients with urinary tract stones, visiting urologist, and also normal people. The level of calcium, oxalate, and citrate in the urinary samples, parathyroid and calcium in the serum samples, and degrading activity of fecal lactobacillus strains of all the subjects were evaluated. Then, data analysis was carried out using SPSS-11.5, χ2 test, Fisher’s exact test, and analysis of variance. Results: The results revealed that the patients had higher urinary level of oxalate and calcium, as well as higher serum level of parathyroid hormone than normal people. In contrast, urinary level of citrate was higher in normal people. In addition, there was a significant difference between the oxalate-degrading capacities of lactobacillus isolated from the patients and their normal peers.Conclusion: Reduction of digestive lactobacillus-related oxalate-degrading capacity and increased serum level of parathyroid hormone can cause elevated urinary level of oxalate and calcium in people with kidney stone.

  12. Effect of surfactants on the degradation of perfluorooctanoic acid (PFOA) by ultrasonic (US) treatment.

    Lin, Jo-Chen; Hu, Ching-Yao; Lo, Shang-Lien

    2016-01-01

    Perfluorooctanoic acid (C7F15COOH, PFOA) is an aqueous anionic surfactant and a persistent organic pollutant. It can be easily adsorbed onto the bubble-water interface and both mineralized and degraded by ultrasonic (US) cavitation at room temperature. The aim of this study is to investigate whether the effect of US on the degradation of PFOA in solution can be enhanced by the addition of surfactant. To achieve this aim, we first investigated the addition of a cationic (hexadecyl trimethyl ammonium bromide, CTAB), a nonionic (octyl phenol ethoxylate, TritonX-100), and an anionic (sodium dodecyl sulfate, SDS) surfactant. We found the addition of CTAB to have increased the degradation rate the most, followed by TritonX-100. SDS inhibited the degradation rate. We then conducted further experiments characterizing the removal efficiency of CTAB at varying surfactant concentrations and solution pHs. The removal efficiency of PFOA increased with CTAB concentration, with the efficiency reaching 79% after 120 min at 25°C with a 0.12 mM CTAB dose. PMID:26384891

  13. Sonocatalytic degradation of Acid Blue 92 using sonochemically prepared samarium doped zinc oxide nanostructures.

    Khataee, Alireza; Saadi, Shabnam; Vahid, Behrouz; Joo, Sang Woo; Min, Bong-Ki

    2016-03-01

    Pure and Sm-doped ZnO nanoparticles were synthesized applying a simple sonochemical method. The nanocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) techniques which confirmed the successful synthesis of the doped sonocatalyst. The sonocatalytic degradation of Acid Blue 92 (AB92), a model azo dye, was more than that with sonolysis alone. The 6% Sm-doped ZnO nanoparticles had a band gap of 2.8 eV and demonstrated the highest activity. The degradation efficiency (DE%) of sonolysis and sonocatalysis with undoped ZnO and 6% Sm-doped ZnO was 45.73%, 63.9%, and 90.10%, after 150 min of treatment, respectively. Sonocatalytic degradation of AB92 is enhanced with increasing the dopant amount and catalyst dosage and with decreasing the initial AB29 concentration. DE% declines with the addition of radical scavengers such as chloride, carbonate, sulfate, and tert-butanol. However, the addition of enhancers including potassium periodates, peroxydisulfate, and hydrogen peroxide improves DE% by producing more free radicals. The results show adequate reusability of the doped sonocatalyst. Degradation intermediates were recognized by gas chromatography-mass spectrometry (GC-MS). Using nonlinear regression analysis, an empirical kinetic model was developed to estimate the pseudo-first-order constants (kapp) as a function of the main operational parameters, including the initial dye concentration, sonocatalyst dosage, and ultrasonic power. PMID:26584981

  14. Effect of Reagents Concentration and Ratio on Degradation of Natural Rubber Latex in Acidic Medium

    The molecular weight of natural rubber (NR) was reduced via degradation to liquid natural rubber (LNR) using hydrogen peroxide and sodium nitrite as reagents in latex solution. In this study, the reaction was carried out in an acidic medium at 70 degree Celsius at various ratio and concentration of reagents. Results showed that the properties of degraded product for example LNR depends on the concentration and ratio of the reagents added into reaction mixtures. Increasing the concentration of hydrogen peroxide and sodium nitrite as reagents at 1 to 1 ratio efficiently reduced the molecular weight of LNR, but the gel content increased when reagents were added more than 0.2 mol. Hydrogen peroxide was found to have greater effect on degradation reaction compared to sodium nitrite when excessive amount of hydrogen peroxide showed further reduction in molecular weight of LNR. The degradation reaction also resulted in the formation of certain functional groups such as hydroxyl and carbonyl as shown from spectroscopy microstructure analysis. (author)

  15. Reactivity of tributyl phosphate degradation products with nitric acid: Relevance to the Tomsk-7 accident

    The reaction of a degraded tributyl phosphate (TBP) solvent with nitric acid is thought to have caused the chemical explosion at the Tomsk-7 reprocessing plant at Tomsk, Russia in 1993. The estimated temperature of the organic layer was not high eneough to cause significant reaction of nitric acid with TBP or hydrocarbon diluent compounds. A more reactive organic compound was likely present in the organic layer that reacted with sufficient heat generation to raise the temperature to the point where an autocatalytic oxidation of the organic solvent was initiated. Two of the most likely reactive compounds that are present in degraded TBP solvents are n-butanol and n-butyl nitrate. The reactions of these compounds with nitric acid are the subject of this study. The objective of laboratory-scale tests was to identify chemical reactions that occur when n-butanol and n-butyl nitrate contact heated nitric acid solutions. Reaction products were identified and quantitified, the temperatures at which these reactions occur and heats of reaction were measured, and reaction variables (temperature, nitric acid concentration, organic concentration, and reaction time) were evaluated. Data showed that n-butyl nitrate is less reactive than n-butanol. An essentially complete oxidation reaction of n-butanol at 110-120 C produced four major reaction products. Mass spectrometry identified the major inorganic oxidation products for both n-butanol and n-butyl nitrate as nitric oxide and carbon dioxide. Calculated heats of reaction for n-butanol and n-butyl nitrate to form propionic acid, a major reaction product, are -1860 cal/g n-butanol and -953 cal/g n-butyl nitrate. These heats of reaction are significant and could have raised the temperature of the organic layer in the Tomsk-7 tank to the point where autocatalytic oxidation of other organic compounds present resulted in an explosion

  16. Characterization of lignocellulosic biomass thermal degradation and physiochemical structure: Effects of demineralization by diverse acid solutions

    Highlights: • HF showed interesting results on EFB (empty fruit bunches) and PMF (palm mesocarp fibre) deashing. • HCl indicated maximum ash removal from PKS (palm kernel shell). • Significant pyrolysis reactions took place at ∼250 °C to ∼400 °C. • Inorganics played a considerable catalytic role during the biomasses pyrolysis. • Acid pretreatment introduced some impacts on the biomasses structure. - Abstract: To eliminate the negative impacts of inorganic constituents during biomass thermochemical processes, leaching method by different diluted acid solutions was chosen. The different palm oil biomass samples (palm kernel shell (PKS), empty fruit bunches (EFB) and palm mesocarp fiber (PMF)) were pretreated by various diluted acid solutions (H2SO4, HClO4, HF, HNO3, HCl). Acids with the highest degrees of demineralization were selected to investigate the dematerialization impacts on the biomass thermal characteristics and physiochemical structure. Thermogravimetric analysis coupled with mass spectroscopy (TGA-MS) and Fourier transform infrared spectroscopy (TGA-FTIR) were employed to examine the biomass thermal degradation. TGA and DTG (Derivative thermogravimetry) indicated that the maximum degradation temperatures increased after acid pretreatment due to the minerals catalytic effects. The main permanent evolved gases comprising H2, CO2, CO were detected online during analysis. The major permanent gases produced at the temperature range of 250–750 °C were attributed to the condensable vapors cracking and probably some secondary reactions. The physiochemical structure change of the acid-treated biomass samples was examined by using Brunauer Emmett Teller (BET) method, Scanning Electron Microscope (SEM) and FTIR. The pyrolysis kinetics of the different palm oil biomasses were investigated using first order reaction model

  17. Research progress and prospects of low phytic acid crops

    The contents and deposit forms of phytic acid and its physiological functions were summarized. The researches on the molecular genetic basis and possible mechanisms of low phytic acid mutations were reviewed, and the future perspectives were discussed. (authors)

  18. Thermodynamic and kinetic aspects of surface acidity. Progress report

    Dumesic, J.A.

    1992-04-01

    Our research in the general area of acid catalysis involves the characterization of solid acidity and the corresponding assessment of catalytic performance of acidic materials. Acid characterization studies are required to provide essential information about the type of acid site (i.e., Lewis versus Bronsted), the strength of the sites, and the mobility of molecules adsorbed on the acid sites. An accurate measure of acid strength is given by the heat of adsorption of a basic probe molecule on the acid site. A thermodynamic representation of the mobility of adsorbed species on these sites is given by the entropy of adsorption. Important techniques used in these acid site characterization studies include microcalorimetry, thermogravimetric measurements, temperature programmed desorption, infrared spectroscopy and solid state nuclear magnetic resonance. The combination of these acid site characterization studies with reaction kinetics measurements of selected catalytic processes allows the elucidation of possible relationships between surface thermodynamic and kinetic properties of acidic sites. Such relationships are important milestones in formulating effective strategies for the effective utilization of solid acid catalysts. Current work in this direction involves methylamine syntheses over various zeolites, and the basic probe molecules employed include ammonia, methanol, water and mono-, di- and tri-methylamines. 31 refs., 18 figs., 1 tab.

  19. Degradation of the Plant Defense Signal Salicylic Acid Protects Ralstonia solanacearum from Toxicity and Enhances Virulence on Tobacco

    Lowe-Power, Tiffany M.; Jacobs, Jonathan M.; Ailloud, Florent; Fochs, Brianna; Prior, Philippe; Allen, Caitilyn

    2016-01-01

    ABSTRACT Plants use the signaling molecule salicylic acid (SA) to trigger defenses against diverse pathogens, including the bacterial wilt pathogen Ralstonia solanacearum. SA can also inhibit microbial growth. Most sequenced strains of the heterogeneous R. solanacearum species complex can degrade SA via gentisic acid to pyruvate and fumarate. R. solanacearum strain GMI1000 expresses this SA degradation pathway during tomato pathogenesis. Transcriptional analysis revealed that subinhibitory SA...

  20. Regulation of protein degradation pathways by amino acids and insulin in skeletal muscle of neonatal pigs

    Agus Suryawan; Teresa ADavis

    2014-01-01

    Background:The rapid gain in lean mass in neonates requires greater rates of protein synthesis than degradation. We previously delineated the molecular mechanisms by which insulin and amino acids, especially leucine, modulate skeletal muscle protein synthesis and how this changes with development. In the current study, we identified mechanisms involved in protein degradation regulation. In experiment 1, 6-and 26-d-old pigs were studied during 1) euinsulinemic-euglycemic-euaminoacidemic, 2) euinsulinemic-euglycemic-hyperaminoacidemic, and 3) hyperinsulinemic-euglycemic-euaminoacidemic clamps for 2 h. In experiment 2, 5-d-old pigs were studied during 1) euinsulinemic-euglycemic-euaminoacidemic-euleucinemic, 2) euinsulinemic-euglycemic-hypoaminoacidemic-hyperleucinemic, and 3) euinsulinemic-euglycemic-euaminoacidemic-hyperleucinemic clamps for 24 h. We determined in muscle indices of ubiquitin-proteasome, i.e., atrogin-1 (MAFbx) and muscle RING-finger protein-1 (MuRF1) and autophagy-lysosome systems, i.e., unc51-like kinase 1 (UKL1), microtubule-associated protein light chain 3 (LC3), and lysosomal-associated membrane protein 2 (Lamp-2). For comparison, we measured ribosomal protein S6 (rpS6) and eukaryotic initiation factor 4E (eIF4E) activation, components of translation initiation. Results:Abundance of atrogin-1, but not MuRF1, was greater in 26-than 6-d-old pigs and was not affected by insulin, amino acids, or leucine. Abundance of ULK1 and LC3 was higher in younger pigs and not affected by treatment. The LC3-II/LC3-I ratio was reduced and ULK1 phosphorylation increased by insulin, amino acids, and leucine. These responses were more profound in younger pigs. Abundance of Lamp-2 was not affected by treatment or development. Abundance of eIF4E, but not rpS6, was higher in 6-than 26-d-old-pigs but unaffected by treatment. Phosphorylation of eIF4E was not affected by treatment, however, insulin, amino acids, and leucine stimulated rpS6 phosphorylation, and the

  1. In vitro degradation of poly (L-co-D,L lactic acid containing PCL-T

    Marcia Adriana Tomaz Duarte

    2014-01-01

    Full Text Available The application of polymer-based bioresorbable temporary devices in the medical field grows continuously, and professionals from several areas act to solve problems related to body functions lost due to diseases, accidents or natural wear. Here we study the influence from poly(caprolactonetriol (PCL-T on the degeneration process in the copolymer poly(L-co-DL-lactic acid (PLDLA membrane, by producing PLDLA/PCL-T blends with 90/10, 70/30 and 50/50 relative concentrations. The data for in vitro degradation showed that PCL-T decreases the rate of PLDLA. This was obtained with the following techniques: Differential Scanning Calorimetry (DSC, Thermogravimetric Analysis (TGA, Gel Permeation Chromatography (GPC and Scanning Electron Microscopy (SEM. Therefore, it is possible to vary the membrane degradation rate by changing the blend composition, which is a tool to tailor a biomaterial.

  2. [Photocatalytic degradation kinetics of perfluorooctanoic acid (PFOA) in TiO2 dispersion and its mechanism].

    Li, Ming-Jie; Yu, Ze-Bin; Chen, Ying; Wang, Li; Liu, Qing; Liu, Yu-Xin; He, Li-Li

    2014-07-01

    Decomposition of perfluorooctanoic acid (PFOA) is of prime importance since it is recognized as a persistent organic pollutant and is widespread in the environment. Heterogeneous photocatalytic decomposition of PFOA by TiO2 (P25) was investigated under 254 nm UV light. Experimental conditions including initial pH, TiO2 content and PFOA concentration, were varied to demonstrate their effects on the decomposition of PFOA. It was observed that the photocatalytic degradation kinetics of PFOA could be fitted to the quasi-first-order equation. The pH played a determinant role in the decomposition of PFOA and the presence of O2 increased the degradation rate. Optimal conditions for a complete removal were obtained using 1.5 g x L(-1) TiO2 at pH 3 in air atmosphere, with a rate constant of 0.420 6 h(-1). The contribution experiments of various reactive species produced during the photocatalysis were also investigated with the addition of different scavengers and it was found that photogenerated holes (h+) was the major reactive species which was responsible for 66.1% of the degradation rate, and the *OH was involved in PFOA degradation as well. In addition, the photocatalytic experiment with the addition of NaF indicated that the adsorption of PFOA was of primary importance for the photocatalytic decomposition. Perfluorocarboxylic acids (PFCAs) with shorter carbon chain length as intermediates and products were identified with UPLC-QTOF/MS, and a possible mechanism for PFOA decomposition was proposed. PMID:25244845

  3. Degradation of U-14C-D-glucose on Dowex-1-X-8(OH-) during displacement with dilute acids

    Slow displacement of U-14C-D-glucose on Dowex-1-X-8(OH-) columns with dilute hydrochloric or acetic acid solutions yields primarily DL-lactic acid alongwith other hydroxy acids. Use of dilute acetic acid appears to favour the formation of the latter products. This finding offers apart from a few synthetic possibilities, a mechanistic interpretation of the degradation sequence. (author). 10 refs

  4. Trifluoroacetic acid from degradation of HCFCs and HFCs: A three-dimensional modeling study

    V. R. Kotamarthi; J. M. Rodriguez; Ko, M. K. W.; Tromp, T. K; Sze, N. D; Prather, Michael J

    1998-01-01

    Trifluoroacetic acid (TFA; CF3 COOH) is produced by the degradation of the halocarbon replacements HFC-134a, HCFC-124, and HCFC-123. The formation of TFA occurs by HFC/HCFC reacting with OH to yield CF3COX (X = F or Cl), followed by in-cloud hydrolysis of CF3COX to form TFA. The TFA formed in the clouds may be reevaporated but is finally deposited onto the surface by washout or dry deposition. Concern has been expressed about the possible long-term accumulation of TFA in certain aquatic envir...

  5. Selection of oleuropein-degrading lactic acid bacteria strains isolated from fermenting Moroccan green olives

    Ghabbour, N.; Lamzira, Z.; Thonart, P.; Cidalia, P.; Markaouid, M.; Asehraoua, A.

    2011-07-01

    A total of 177 strains of lactic acid bacteria (LAB) were isolated from early-stage Moroccan Picholine green olive fermentation, including Lactobacillus plantarum (44.63%), Lactobacillus pentosus (25.99%), Lactobacillus brevis (9.61%) and Pediococcus pentosaceus (19.77%). All the isolates were screened for their tolerance to olive leaf extract and oleuropein. Most of the isolates (85.3%) were found able to degrade oleuropein, when evaluated by either oleuropein or 5-Bromo-4-chloro-3-indolyl {beta}-D-glucuronide (X-Gluc) as substrates. The biodegradation capacity of the selected strains of each species was confirmed by HPLC analysis. (Author).

  6. Selection of oleuropein-degrading lactic acid bacteria strains isolated from fermenting Moroccan green olives

    A total of 177 strains of lactic acid bacteria (LAB) were isolated from early-stage Moroccan Picholine green olive fermentation, including Lactobacillus plantarum (44.63%), Lactobacillus pentosus (25.99%), Lactobacillus brevis (9.61%) and Pediococcus pentosaceus (19.77%). All the isolates were screened for their tolerance to olive leaf extract and oleuropein. Most of the isolates (85.3%) were found able to degrade oleuropein, when evaluated by either oleuropein or 5-Bromo-4-chloro-3-indolyl β-D-glucuronide (X-Gluc) as substrates. The biodegradation capacity of the selected strains of each species was confirmed by HPLC analysis. (Author).

  7. Selection of oleuropein-degrading lactic acid bacteria strains isolated from fermenting Moroccan green olives

    Ghabbour, N.; Lamzira, Z.; Thonart, P.; Cidalia, P.; Markaoui, M.; Asehraou, A.

    2011-01-01

    A total of 177 strains of lactic acid bacteria (LAB) were isolated from early-stage Moroccan Picholine green olive fermentation, including Lactobacillus plantarum (44.63%), Lactobacillus pentosus (25.99%), Lactobacillus brevis (9.61%) and Pediococcus pentosaceus (19.77%). All the isolates were screened for their tolerance to olive leaf extract and oleuropein. Most of the isolates (85.3%) were found able to degrade ole...

  8. Cullin 3 mediates SRC-3 ubiquitination and degradation to control the retinoic acid response

    Ferry, Christine; Gaouar, Samia; Fischer, Benoit; Boeglin, Marcel; Paul, Nicodeme; Samarut, Eric; Piskunov, Aleksandr; Pankotai-Bodo, Gabriella; Brino, Laurent; Rochette-Egly, Cecile

    2011-01-01

    SRC-3 is an important coactivator of nuclear receptors including the retinoic acid (RA) receptor α. Most of SRC-3 functions are facilitated by changes in the posttranslational code of the protein that involves mainly phosphorylation and ubiquitination. We recently reported that SRC-3 is degraded by the proteasome in response to RA. Here, by using an RNAi E3-ubiquitin ligase entry screen, we identified CUL-3 and RBX1 as components of the E3 ubiquitin ligase involved in the RA-induced ubiquitin...

  9. Effect of Ascorbic Acid on the Degradation of Cyanocobalamin and Hydroxocobalamin in Aqueous Solution: A Kinetic Study

    Ahmad, Iqbal; Qadeer, Kiran; Zahid, Saima; SHERAZ, MUHAMMAD ALI; Ismail, Tehmina; Hussain, Waqar; Ansari, Izhar Ahmad

    2014-01-01

    The degradation kinetics of 5 × 10−5 M cyanocobalamin (B12) and hydroxocobalamin (B12b) in the presence of ascorbic acid (AH2) was studied in the pH range of 1.0–8.0. B12 is degraded to B12b which undergoes oxidation to corrin ring cleavage products. B12b alone is directly oxidized to the ring cleavage products. B12 and B12b in degraded solutions were simultaneously assayed by a two-component spectrometric method at 525 and 550 nm without interference from AH2. Both degrade by first-order kin...

  10. Salicylic acid antagonizes abscisic acid inhibition of shoot growth and cell cycle progression in rice

    Meguro, Ayano; Sato, Yutaka

    2014-04-01

    We analysed effects of abscisic acid (ABA, a negative regulatory hormone), alone and in combination with positive or neutral hormones, including salicylic acid (SA), on rice growth and expression of cell cycle-related genes. ABA significantly inhibited shoot growth and induced expression of OsKRP4, OsKRP5, and OsKRP6. A yeast two-hybrid assay showed that OsKRP4, OsKRP5, and OsKRP6 interacted with OsCDKA;1 and/or OsCDKA;2. When SA was simultaneously supplied with ABA, the antagonistic effect of SA completely blocked ABA inhibition. SA also blocked ABA inhibition of DNA replication and thymidine incorporation in the shoot apical meristem. These results suggest that ABA arrests cell cycle progression by inducing expression of OsKRP4, OsKRP5, and OsKRP6, which inhibit the G1/S transition, and that SA antagonizes ABA by blocking expression of OsKRP genes.

  11. Soil degradation by sulfuric acid disposition on uranium producing sites in south Bulgaria

    This study assesses the damage of soils caused by spills of sulfuric acid solutions used for in situ leaching of uranium at eight uranium producing (by open-cast method) sites (total area of approximately 220 ha) in the region of Momino-Rakovski (South Bulgaria). The upper soil layer is cinnamonic pseudopodzolic ( or Eutric Planosols by FAO Legend, 1974). The results of the investigation show that the sulfuric acid spills caused strong acidification of upper (0-20 cm) and subsurface (20-60 cm) soil horizons which is expressed as decreasing of pH (H2O) to 2.9-3.5 and increasing of exchangeable H+ and Al3+ to 18 and 32% from CEC. Acid degradation of soils is combined with reducing of organic matter content. The average concentration of the total heavy metal content in the upper soil horizon (in ppm) is: Cd=1.5; Cu=30; Pb=25; Zn=40 and U=8. No significant differences were detected between the upper and subsurface soil layers . The heavy metal concentration did not exceed the Bulgarian standards for heavy metals and uranium content of soils. But the coarse texture of the top soil layers, the lack of carbonates, The low CEC and strong acidity determine a low buffering capacity of the investigated soils and this can be considered as hazardous for plants. This indicates that a future soil monitoring should be carried out in the region together with measures for neutralizing of soil acidity

  12. Degradation of reactive, acid and basic textile dyes in the presence of ultrasound and rare earths [Lanthanum and Praseodymium].

    Srivastava, Pankaj; Goyal, Shikha; Patnala, Prem Kishore

    2014-11-01

    Degradation of five textile dyes, namely Reactive Red 141 (RR 141), Reactive Blue 21 (RB 21), Acid Red 114 (AR 114), Acid Blue 113 (AB 113) and Basic Violet 16 (BV 16) in aqueous solution has been carried out with ultrasound (US) and in combination with rare earth ions (La(3+) and Pr(3+)). Kinetic analysis of the data showed a pseudo-first order degradation reaction for all the dyes. The rate constant (k), half life (t1/2) and the process efficiency (φ) for various processes in degradation of dyes under different experimental conditions have been calculated. The influence of concentrations of dyes (16-40mg/L), pH (5, 7 and 9) and rare earth ion concentration (4, 12 and 20mg/L) on the degradation of dyes have also been studied. The degradation percentage increased with increasing rare earth amount and decreased with increasing concentration of dyes. Both horn and bath type sonicators were used at 20kHz and 250W for degradation. The sonochemical degradation rate of dyes in the presence of rare earths was related to the type of chromophoric groups in the dye molecule. Degradation sequence of dyes was further examined through LCMS and Raman spectroscopic techniques, which confirmed the sonochemical degradation of dyes to non-toxic end products. PMID:24491599

  13. Strecker degradation of amino acids promoted by a camphor-derived sulfonamide.

    Carvalho, M Fernanda N N; Ferreira, M João; Knittel, Ana S O; Oliveira, Maria da Conceição; Costa Pessoa, João; Herrmann, Rudolf; Wagner, Gabriele

    2016-01-01

    A camphor-derived sulfonimine with a conjugated carbonyl group, oxoimine 1 (O2SNC10H13O), reacts with amino acids (glycine, L-alanine, L-phenylalanine, L-leucine) to form a compound O2SNC10H13NC10H14NSO2 (2) which was characterized by spectroscopic means (MS and NMR) and supported by DFT calculations. The product, a single diastereoisomer, contains two oxoimine units connected by a -N= bridge, and thus has a structural analogy to the colored product Ruhemann´s purple obtained by the ninhydrin reaction with amino acids. A plausible reaction mechanism that involves zwitterions, a Strecker degradation of an intermediate imine and water-catalyzed tautomerizations was developed by means of DFT calculations on potential transition states. PMID:27340465

  14. Strecker degradation of amino acids promoted by a camphor-derived sulfonamide

    Ferreira, M João; Knittel, Ana S O; Oliveira, Maria da Conceição; Costa Pessoa, João; Herrmann, Rudolf; Wagner, Gabriele

    2016-01-01

    Summary A camphor-derived sulfonimine with a conjugated carbonyl group, oxoimine 1 (O2SNC10H13O), reacts with amino acids (glycine, L-alanine, L-phenylalanine, L-leucine) to form a compound O2SNC10H13NC10H14NSO2 (2) which was characterized by spectroscopic means (MS and NMR) and supported by DFT calculations. The product, a single diastereoisomer, contains two oxoimine units connected by a –N= bridge, and thus has a structural analogy to the colored product Ruhemann´s purple obtained by the ninhydrin reaction with amino acids. A plausible reaction mechanism that involves zwitterions, a Strecker degradation of an intermediate imine and water-catalyzed tautomerizations was developed by means of DFT calculations on potential transition states.

  15. [Simulated study of algal fatty acid degradation in hypoxia seawater-sediment interface along China coastal area].

    Sui, Wei-Wei; Ding, Hai-Bing; Yang, Gui-Peng; Lu, Xiao-Lan; Li, Wen-Juan; Sun, Li-Qun

    2013-11-01

    Series of laboratory incubation experiments were conducted to simulate degradation of organic matter in sediment-seawater interface in hypoxia enviroments along China coastal area. Under four different redox conditions (oxygen saturation: 100%, 50%, 25% and 0%), degradations of seveal biomarkers originated from Skeletonema costatum, a typical red tide alage along China coastal area were tracked. By analyzing concentrations of four fatty acid biomarkers [14:0, 16:0, 16:1(7) and 20:5] obtained at various sampling time, results showed that their concentrations decreased significantly after 2-3 weeks' incubation. Then, their concentrations changed very slowly or very little. However, degradation of the four fatty acids varied dramatically in different incubation systems. Fatty acids 14:0, 16:1(7) and 20:5 were degraded completely in all incubation systems after two-month incubation, but 25% to 35% of 16:0 was reserved in the systems. Based on multi-G model, degradations of the four fatty acids were quantively described. The results indicated that all four fatty acids had fast-degraded and slow-degraded fractions. Their degradation rate constants (k(av)) ranged from 0.079 to 0.84 d(-1). The fastest degradation of 14:0 and 16:1 (7) occurred under 25% oxygen concentrations. For these two compounds, in the fastest degradation system, their k(av), values were 2.3 folds and 1.7 folds higher than those in the slowest degradation system [50% oxygen saturation for 14:0 and 100% oxygen saturation for 16:1(7)] respectively. The 16:0 was degraded fastest under the anoxic condition and slowest under the 50% oxygen saturation. The ratio of the two k(av)s was 2.1. The k(av)s of 20:5 had a positive relationship with oxygen saturations. Results of this study suggested that besides oxgen saturations, structure and features of organic compounds, roles of microbe in the envrioments and etc. might affect degradations of fatty acids in S. costatum in hypoxia sediment-seawater interface

  16. Chaperone-Mediated Autophagy Targets IFNAR1 for Lysosomal Degradation in Free Fatty Acid Treated HCV Cell Culture.

    Ramazan Kurt

    Full Text Available Hepatic steatosis is a risk factor for both liver disease progression and an impaired response to interferon alpha (IFN-α-based combination therapy in chronic hepatitis C virus (HCV infection. Previously, we reported that free fatty acid (FFA-treated HCV cell culture induces hepatocellular steatosis and impairs the expression of interferon alpha receptor-1 (IFNAR1, which is why the antiviral activity of IFN-α against HCV is impaired.To investigate the molecular mechanism by which IFNAR1 expression is impaired in HCV cell culture with or without free fatty acid-treatment.HCV-infected Huh 7.5 cells were cultured with or without a mixture of saturated (palmitate and unsaturated (oleate long-chain free fatty acids (FFA. Intracytoplasmic fat accumulation in HCV-infected culture was visualized by oil red staining. Clearance of HCV in FFA cell culture treated with type I IFN (IFN-α and Type III IFN (IFN-λ was determined by Renilla luciferase activity, and the expression of HCV core was determined by immunostaining. Activation of Jak-Stat signaling in the FFA-treated HCV culture by IFN-α alone and IFN-λ alone was examined by Western blot analysis and confocal microscopy. Lysosomal degradation of IFNAR1 by chaperone-mediated autophagy (CMA in the FFA-treated HCV cell culture model was investigated.FFA treatment induced dose-dependent hepatocellular steatosis and lipid droplet accumulation in HCV-infected Huh-7.5 cells. FFA treatment of infected culture increased HCV replication in a concentration-dependent manner. Intracellular lipid accumulation led to reduced Stat phosphorylation and nuclear translocation, causing an impaired IFN-α antiviral response and HCV clearance. Type III IFN (IFN-λ, which binds to a separate receptor, induces Stat phosphorylation, and nuclear translocation as well as antiviral clearance in FFA-treated HCV cell culture. We show here that the HCV-induced autophagy response is increased in FFA-treated cell culture

  17. Malic acid or orthophosphoric acid-heat treatments for protecting sunflower (Helianthus annuus) meal proteins against ruminal degradation and increasing intestinal amino acid supply.

    Arroyo, J M; González, J; Ouarti, M; Silván, J M; Ruiz del Castillo, M L; de la Peña Moreno, F

    2013-02-01

    The protection of sunflower meal (SFM) proteins by treatments with solutions of malic acid (1 M) or orthophosphoric acid (0.67 M) and heat was studied in a 3 × 3 Latin-square design using three diets and three rumen and duodenum cannulated wethers. Acid solutions were applied to SFM at a rate of 400 ml/kg under continuous mixing. Subsequently, treated meals were dried in an oven at 150°C for 6 h. Diets (ingested at 75 g/kg BW0.75) were isoproteic and included 40% Italian ryegrass hay and 60% concentrate. The ratio of untreated to treated SFM in the concentrate was 100 : 0 in the control diet and around 40 : 60 in diets including acid-treated meals. The use of acid-treated meals did not alter either ruminal fermentation or composition of rumen contents and led to moderate reductions of the rumen outflow rates of untreated SFM particles, whereas it did not affect their comminution and mixing rate. In situ effective estimates of by-pass (BP) and its intestinal effective digestibility (IED) of dry matter (DM), CP and amino acids (AAs) were obtained considering both rates and correcting the particle microbial contamination in the rumen using 15N infusion techniques. Estimates of BP and IED decreased applying microbial correction, but these variations were low in agreement with the small contamination level. Protective treatments increased on average the BP of DM (48.5%) and CP (267%), mainly decreasing both the soluble fraction and the degradation rate but also increasing the undegradable fraction, which was higher using orthophosphoric acid. Protective treatments increased the IED of DM (108%) and CP, but this increase was lower using orthophosphoric acid (11.8%) than malic acid (20.7%). Concentrations of AA were similar among all meals, except for a reduction in lysine concentrations using malic acid (16.3%) or orthophosphoric acid (20.5%). Protective treatments also increased on average the BP of all AA, as well as the IED of most of them. Evidence of higher

  18. Degradation studies of transparent conductive electrodes on electroactive poly(vinylidene fluoride for uric acid measurements

    Vanessa F Cardoso, Pedro Martins, Gabriela Botelho, Luis Rebouta, Senentxu Lanceros-Méndez and Graca Minas

    2010-01-01

    Full Text Available Biochemical analysis of physiological fluids using, for example, lab-on-a-chip devices requires accurate mixing of two or more fluids. This mixing can be assisted by acoustic microagitation using a piezoelectric material, such as the β-phase of poly(vinylidene fluoride (β-PVDF. If the analysis is performed using optical absorption spectroscopy and β-PVDF is located in the optical path, the material and its conductive electrodes must be transparent. Moreover, if, to improve the transmission of the ultrasonic waves to the fluids, the piezoelectric transducer is placed inside the fluidic structures, its degradation must be assessed. In this paper, we report on the degradation properties of transparent conductive oxides, namely, indium tin oxide (ITO and aluminum-doped zinc oxide, when they are used as electrodes for providing acoustic microagitation. The latter promotes mixing of chemicals involved in the measurement of uric acid concentration in physiological fluids. The results are compared with those for aluminum electrodes. We find that β-PVDF samples with ITO electrodes do not degrade either with or without acoustic microagitation.

  19. Oil sands to the rescue: oil sand microbial communities can degrade recalcitrant alkyl phenyl alkanoic acids

    Whitby, Corinne [University of Essex (Canada)], email: cwhitby@essex.ac.uk

    2011-07-01

    Almost half of all global oil reserves are found as biodegraded heavy oils found in vast tar sand deposits located in North and South America and these account for 47% of Canadian oil production. Oil sand extraction generates large amounts of toxic waste water, known as oil sand process waters (OSPW), that are stored in large tailing ponds that contain toxic compounds like naphthenic acids (NAs). The presence of NAs creates problems like toxicity, corrosion, and the formation of calcium napthenate deposits which block pipelines and other infrastructure and need to be removed. This paper presents oil sand microbial communities that can degrade these NAs. The approach is to apply new aliphatic and aromatic NAs as substrates to supplement and identify NA degrading microbes and also to identify the metabolites produced and explain NA degradation pathways and the functional genes involved. The chemistry and the processes involved are explained. From the results, it is suggested that pure cultures of P. putida KT2440 be used against NAs.

  20. Progress Towards Understanding the Degradation and Performance Characteristics of the PROBA2-LYRA Instrument

    Jones, A. R.; McMullin, D. R.; Dominique, M.; Dammasch, I.

    2013-12-01

    The Large Yield Radiometer, LYRA is a solar radiometer on the ESA PROBA2 spacecraft launched November 2, 2009. LYRA has been designed to provide measurements of the solar XUV to MUV (soft X-ray to middle ultraviolet) region of the solar spectrum. The LYRA instrument observes in four broad spectral channels, from soft X-ray to UV, chosen for their relevance to solar physics and space weather. Each of the four channels has the capability of acquiring irradiance measurements at a nominal cadence of 20 Hz, but can be increased to 100 Hz. Each of the four channels has suffered from significant degradation almost immediately after launch. The degradation observed in the LYRA channels is significant and detrimental to the potential science. Preliminary work in this effort has shown that the most likely cause of the observed degradation is contaminant buildup on the filters at the front of the instrument. In this work, we present initial results of our investigation into the performance characteristics and observed degradation. We have developed and will present results from our three-step approach: 1. Develop models for each LYRA channel using measured calibrations and instrument design parameters; 2. Use the models to estimate the sensitivity changes due to possible degradation sources (thickness and composition); 3. Evaluate corrected sensor performance by comparing the measured data with independent measurements from currently operating instruments.

  1. Degradation of Acid Orange 7 Dye in Two Hybrid Plasma Discharge Reactors

    Shen, Yongjun; Lei, Lecheng; Zhang, Xingwang; Ding, Jiandong

    2014-11-01

    To get an optimized pulsed electrical plasma discharge reactor and to increase the energy utilization efficiency in the removal of pollutants, two hybrid plasma discharge reactors were designed and optimized. The reactors were compared via the discharge characteristics, energy transfer efficiency, the yields of the active species and the energy utilization in dye wastewater degradation. The results showed that under the same AC input power, the characteristics of the discharge waveform of the point-to-plate reactor were better. Under the same AC input power, the two reactors both had almost the same peak voltage of 22 kV. The peak current of the point-to-plate reactor was 146 A, while that of the wire-to-cylinder reactor was only 48.8 A. The peak powers of the point-to-plate reactor and the wire-to-cylinder reactor were 1.38 MW and 1.01 MW, respectively. The energy per pulse of the point-to-plate reactor was 0.2221 J, which was about 29.4% higher than that of the wire-to-cylinder reactor (0.1716 J). To remove 50% Acid Orange 7 (AO7), the energy utilizations of the point-to-plate reactor and the wire-to-cylinder reactor were 1.02 × 10-9 mol/L and 0.61 × 10-9 mol/L, respectively. In the point-to-plate reactor, the concentration of hydrogen peroxide in pure water was 3.6 mmol/L after 40 min of discharge, which was higher than that of the wire-to-cylinder reactor (2.5 mmol/L). The concentration of liquid phase ozone in the point-to-plate reactor (5.7 × 10-2 mmol/L) was about 26.7% higher than that in the wire-to-cylinder reactor (4.5 × 10-2 mmol/L). The analysis results of the variance showed that the type of reactor and reaction time had significant impacts on the yields of the hydrogen peroxide and ozone. The main degradation intermediates of AO7 identified by gas chromatography and mass spectrometry (GCMS) were acetic acid, maleic anhydride, p-benzoquinone, phenol, benzoic acid, phthalic anhydride, coumarin and 2-naphthol. Proposed degradation pathways were

  2. Characterization of sericin powder prepared from citric acid-degraded sericin polypeptides of the silkworm, Bombyx Mori.

    Kurioka, Akira; Kurioka, Fujie; Yamazaki, Masayoshi

    2004-04-01

    Acid-degraded sericin powder (AC-SP) was prepared from aqueous solution containing citric acid-degraded sericin polypeptides of Bombyx mori. The morphological and biochemical properties of AC-SP were compared with those of alkali-degraded sericin powder (AL-SP) and hot-water degraded sericin powder (HW-SP). Based on an SEM analysis, AC-SP showed a thin film structure of 10-100 microm with good dispersity while AL-SP and HW-SP had a much larger thin film structure (<500 microm). The extract of AC-SP showed stronger trypsin inhibitor activity due to cocoon shell trypsin inhibitor (CSTI-IV) than that of HW-SP. The extract of AL-SP showed no CSTI-IV activity. It was found that AC-SP was a trypsin inhibitor complex powder and that the release of CSTI-IV from AC-SP depended on pH and ion strength. Similar powder materials were obtained when such organic acids as tartaric acid and succinic acid were used. These results suggest that the acid-degraded sericin polypeptides work as a protein matrix to which CSTI-IV may bind ionically. PMID:15118302

  3. Homogeneous and heterogeneous degradation of caffeic acid using photocatalysis driven by UVA and solar light.

    Yáñez, Eliana; Santander, Paola; Contreras, David; Yáñez, Jorge; Cornejo, Lorena; Mansilla, Héctor D

    2016-01-01

    Waste water from the wine industry is characterized by a high concentration of dissolved organic matter and the presence of natural phenolic compounds with low biodegradability. High concentrations of phenolic compounds may cause environmental pollution and risks to human health. In this article caffeic acid (CA) was used as a model compound of wine effluent because it is refractory to the conventional wastewater treatments. The oxidation of caffeic acid in water solution (0.01 g L(-1)) by heterogeneous photocatalysis and photo-Fenton reaction was studied using UVA. The optimal conditions for each treatment were performed by multivariate experimental design. The optimal conditions for heterogeneous photocatalysis were pH 5.3 and 0.9 g L(-1) TiO2. In the case of photo-Fenton treatment, optimized variable were 82.4 μmol L(-1) of Fe(2+) and 558.6 μmol L(-1) of H2O2. The degradation profiles of CA were monitored by UV-Vis, HPLC, TOC and COD. To reach 90% of CA removal, 40 and 2 min of reaction, respectively, were required by heterogeneous and photo-Fenton processes, respectively. For comparison purposes, the reactions were also performed under solar light. The use of solar light does not change the efficiency of the photo-Fenton reaction, yet the performance of the heterogeneous process was significantly improved, reaching 90% of degradation in 15 min. PMID:26548918

  4. Photoelectrocatalytic degradation of oxalic acid by spray deposited nanocrystalline zinc oxide thin films

    Shinde, S.S. [Electrochemical Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416004 (India); Shinde, P.S. [Department of Nano-Engineering, Kyungnam University, Masan 631-701 (Korea, Republic of); Sapkal, R.T. [Electrochemical Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416004 (India); Oh, Y.W. [Department of Nano-Engineering, Kyungnam University, Masan 631-701 (Korea, Republic of); Haranath, D. [National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110 012 (India); Bhosale, C.H. [Electrochemical Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416004 (India); Rajpure, K.Y., E-mail: rajpure@yahoo.com [Electrochemical Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416004 (India)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer Influence of substrate temperature onto the physico-chemical properties. Black-Right-Pointing-Pointer Photochemical, structural, luminescent, optoelectrical and thermal properties. Black-Right-Pointing-Pointer The kinetics of oxalic acid degradation with reaction mechanism. Black-Right-Pointing-Pointer Extent of mineralization by COD and TOC. - Abstract: The high quality nano-crystalline zinc oxide thin films are deposited onto corning glasses by spray pyrolysis technique. The influence of reaction temperature onto their photoelectrochemical, structural, morphological, optoelectronic, luminescence and thermal properties has been investigated. The structural characteristics studied by X-ray diffractometry has complemented by resistivity measurements and UV-Vis spectroscopy. The photoelectrochemical activity shows enhancement in short circuit current (I{sub sc} = 0.357 mA) and open circuit voltage (V{sub oc} = 0.48 V). Direct band gap calculated by considering R and T values of ZnO thin films increases from 3.14-3.21 eV exhibiting a slight blue shift in band edge. Three characteristic luminescence peaks having near band-edge, blue and green emission are observed in the photoluminescence spectra. The specific heat and thermal conductivity study shows the phonon conduction behavior is dominant in films. Photocatalytic degradation of oxalic acid followed with reaction mechanism by using zinc oxide photoelectrode under solar illumination has been investigated.

  5. Photoelectrocatalytic degradation of oxalic acid by spray deposited nanocrystalline zinc oxide thin films

    Highlights: ► Influence of substrate temperature onto the physico-chemical properties. ► Photochemical, structural, luminescent, optoelectrical and thermal properties. ► The kinetics of oxalic acid degradation with reaction mechanism. ► Extent of mineralization by COD and TOC. - Abstract: The high quality nano-crystalline zinc oxide thin films are deposited onto corning glasses by spray pyrolysis technique. The influence of reaction temperature onto their photoelectrochemical, structural, morphological, optoelectronic, luminescence and thermal properties has been investigated. The structural characteristics studied by X-ray diffractometry has complemented by resistivity measurements and UV–Vis spectroscopy. The photoelectrochemical activity shows enhancement in short circuit current (Isc = 0.357 mA) and open circuit voltage (Voc = 0.48 V). Direct band gap calculated by considering R and T values of ZnO thin films increases from 3.14–3.21 eV exhibiting a slight blue shift in band edge. Three characteristic luminescence peaks having near band-edge, blue and green emission are observed in the photoluminescence spectra. The specific heat and thermal conductivity study shows the phonon conduction behavior is dominant in films. Photocatalytic degradation of oxalic acid followed with reaction mechanism by using zinc oxide photoelectrode under solar illumination has been investigated.

  6. Radiolytic and chemical degradation of strong acidic ion-exchange resins: Study of ligands formed

    The formation of water-soluble organic ligands by radiolytic and chemical degradation of several strong acidic ion-exchange resins was investigated under conditions close to those of the near field of a cementitious repository. The most important degradation products were studied and their complexing properties evaluated. Irradiation of strong acidic cation exchange resins (Powder PCH and Lewatite S-100) resulted in the formation of mainly sulfate and dissolved organic carbon. High-performance liquid chromatography analysis indicated the presence of oxalate, contributing to 10 to 20% of the organic carbon. The identity of the remainder is unknown. The presence of oxalate as a complexant is consistent with results from earlier work. Complexation studies with Cu2+ and Ni2+ showed the presence of two ligands: oxalate and ligand X. Although ligand X could not be identified, it could be characterized by its concentration ([X]T ∼ 10-5 to 10-6 M), a deprotonation constant (pKH approximately 7.4 at I = 0.1 M), and a complexation constant for the NiX complex (log KNiXapproximately 7.0 at I = 0.1 M). In the absence of irradiation, no evidence for the formation of ligands was found

  7. Solar photocatalytic degradation of naphthenic acids in oil sands process-affected water.

    Leshuk, Tim; Wong, Timothy; Linley, Stuart; Peru, Kerry M; Headley, John V; Gu, Frank

    2016-02-01

    Bitumen mining in the Canadian oil sands creates large volumes of oil sands process-affected water (OSPW), the toxicity of which is due in part to naphthenic acids (NAs) and other acid extractable organics (AEO). The objective of this work was to evaluate the potential of solar photocatalysis over TiO2 to remove AEO from OSPW. One day of photocatalytic treatment under natural sunlight (25 MJ/m(2) over ∼14 h daylight) eradicated AEO from raw OSPW, and acute toxicity of the OSPW toward Vibrio fischeri was eliminated. Nearly complete mineralization of organic carbon was achieved within 1-7 day equivalents of sunlight exposure, and degradation was shown to proceed through a superoxide-mediated oxidation pathway. High resolution mass spectrometry (HRMS) analysis of oxidized intermediate compounds indicated preferential degradation of the heavier and more cyclic NAs (higher number of double bond equivalents), which are the most environmentally persistent fractions. The photocatalyst was shown to be recyclable for multiple uses, and thus solar photocatalysis may be a promising "green" advanced oxidation process (AOP) for OSPW treatment. PMID:26539710

  8. Laboratory study on OH-initiated degradation kinetics of dehydroabietic acid.

    Lai, Chengyue; Liu, Yongchun; Ma, Jinzhu; Ma, Qingxin; He, Hong

    2015-04-28

    Dehydroabietic acid (DHAA) is a specific organic tracer for the pyrolysis of conifer resin. To understand its atmospheric stability, the degradation behavior of particulate DHAA in the presence of hydroxyl radicals (OH) was investigated under different environmental conditions using a stainless steel reactor with volume of 30 cm(3), in the dark. At 25 °C and 40% relative humidity (RH), the second-order rate constant (k2) of pure DHAA with OH was measured to be 5.72 ± 0.87 × 10(-12) cm(3) molecule(-1) s(-1). The influence of temperature, RH and mixing state on the degradation kinetics of DHAA were also investigated. At 40% RH, k2 of pure DHAA increases with increasing temperature and follows the Arrhenius equation k2 = (8.9 ± 1.9) × 10(-10) exp[-(1508.2 ± 64.2)/T], while RH does not have significant impact on k2 at 25 °C. At 25 °C and 40% RH, compared with pure DHAA, the corresponding k2 for DHAA mixed with (NH4)2SO4 decreased to 4.58 ± 0.95 × 10(-12) cm(3) molecule(-1) s(-1), while the value was 3.30 ± 0.79 × 10(-12) cm(3) molecule(-1) s(-1) when mixed with soot. The atmospheric lifetime of DHAA varied from 2.3 ± 0.2 to 4.4 ± 0.8 days under different environmental conditions. This study indicates that degradation of DHAA by OH radicals is appreciable, and a significant error in source apportionment should be introduced if the contribution of degradation to DHAA concentration is not considered during air mass aging. PMID:25824374

  9. Anodic oxidation of salicylic acid on BDD electrode: Variable effects and mechanisms of degradation

    Rabaaoui, Nejmeddine, E-mail: chimie_tunisie@yahoo.fr [Faculte des Sciences de Sfax, Departement de Chimie, 3038 Sfax (Tunisia); Allagui, Mohamed Salah [Faculte des Sciences de Gafsa, Campus Universitaire Sidi Ahmed Zarrouk, 2112 Gafsa (Tunisia)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer Oxidation with BDD is a powerful electrochemical method able to mineralize. Black-Right-Pointing-Pointer SA is oxidized to aromatic compounds then CO{sub 2} and H{sub 2}O. Black-Right-Pointing-Pointer Polymeric intermediate products were formed. - Abstract: The degradation of 100 mL of solution with salicylic acid (SA) in the pH range 3.0-10.0 has been studied by anodic oxidation in a cell with a boron-doped diamond (BDD) anode and a stainless steel cathode, both of 3 cm{sup 2} area, by applying a current of 100, 300 and 450 mA at 25 Degree-Sign C. Completed mineralization is always achieved due to the great concentration of hydroxyl radical ({center_dot}OH) generated at the BDD surface. The mineralization rate increases with increasing applied current, but decreases when drug concentration rises from 200 mg L{sup -1}. Nevertheless, the pH effect was not significant. During oxidation it was observed that catechol, 2,5-dihydroxylated benzoic acid, 2,3-dihydroxylated benzoic acid and hydroquinone were formed as aromatic intermediates. In addition, ion-exclusion chromatography allowed the detection of fumaric, maleic, oxalic and formic as the ultimate carboxylic acid.

  10. Anodic oxidation of salicylic acid on BDD electrode: Variable effects and mechanisms of degradation

    Highlights: ► Oxidation with BDD is a powerful electrochemical method able to mineralize. ► SA is oxidized to aromatic compounds then CO2 and H2O. ► Polymeric intermediate products were formed. - Abstract: The degradation of 100 mL of solution with salicylic acid (SA) in the pH range 3.0–10.0 has been studied by anodic oxidation in a cell with a boron-doped diamond (BDD) anode and a stainless steel cathode, both of 3 cm2 area, by applying a current of 100, 300 and 450 mA at 25 °C. Completed mineralization is always achieved due to the great concentration of hydroxyl radical (·OH) generated at the BDD surface. The mineralization rate increases with increasing applied current, but decreases when drug concentration rises from 200 mg L−1. Nevertheless, the pH effect was not significant. During oxidation it was observed that catechol, 2,5-dihydroxylated benzoic acid, 2,3-dihydroxylated benzoic acid and hydroquinone were formed as aromatic intermediates. In addition, ion-exclusion chromatography allowed the detection of fumaric, maleic, oxalic and formic as the ultimate carboxylic acid.

  11. Evaluation of the performance degradation at PAFC effect of operating conditions on acid loss

    Miyoshi, Hideaki; Uchida, Hiroyuki; Watanabe, Masahiro [Yamanashi Univ., Kofu (Japan)] [and others

    1996-12-31

    As a complimentary research project to the demonstration project of 5MW and 1 MW PAFC plants, the mechanism and rate of deterioration of the cells and stacks have been studied from 1995 FY conducted by NEDO, with the objective of establishing an estimation method for the service life-time of the cell stacks. As part of this project, this work has been performed to clarify basic phenomena of the performance degradation at PAFCs jointly by Yamanashi University, PAFC-TRA and PAFC manufacturers. The acid loss into exhaust gases is one of life limiting factors in PAFCs. To design the cells of long-life, it is important to estimate the phosphoric acid loss and to contrive ideas eliminating it. With the objective of obtaining basic data for simulating the acid loss in the large size cells, the effect of the operating conditions on the acid loss into exhaust gases has been studied experimentally by using a single cell with an active electrode area of 100 cm{sup 2}.

  12. Electrochemical assisted photocatalytic degradation of salicylic acid with highly ordered TiO{sub 2} nanotube electrodes

    Zhang, Qian [The State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Zhu, Jinwei [China Aerospace Science and Technology Corporation Fourty-fourth Research Institution (China); Wang, Ying; Feng, Jiangtao [Department of Environmental Science and Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Yan, Wei, E-mail: yanwei@mail.xjtu.edu.cn [The State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Department of Environmental Science and Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Xu, Hao, E-mail: xuhao@mail.xjtu.edu.cn [Department of Environmental Science and Engineering, Xi’an Jiaotong University, Xi’an 710049 (China)

    2014-07-01

    To explore the kinetics of photoelectrocatalytic degradation of salicylic acid, one of the important PPCPs, highly ordered TiO{sub 2} nanotube arrays (NTs) were prepared by the electrochemical anodization and characterized with scanning electron microscopy and X-ray diffraction techniques. The effect of TiO{sub 2} NTs properties, bias potential, initial salicylic acid concentration and solution pH on the degradation efficiency was studied and carefully analyzed. The results revealed that the salicylic acid degradation follows quasi-first order kinetics in the photoelectrocatalytic process, and the fastest decay kinetics was achieved in acidic environment (pH 2). The result was further interpreted through the electrochemical impedance spectroscopy. It is confirmed that the electrochemical assisted photocatalysis is a synergetic approach to combat stable organic substances with improved efficiency.

  13. Polylactic acid coating on a biodegradable magnesium alloy: An in vitro degradation study by electrochemical impedance spectroscopy

    Alabbasi, Alyaa; Liyanaarachchi, S.; Kannan, M. Bobby, E-mail: bobby.mathan@jcu.edu.au

    2012-09-30

    Polylactic acid (PLA) was coated on a biodegradable magnesium alloy, AZ91, using spin coating technique for temporary implant applications. The degradation behaviour of the coated alloy samples was evaluated using electrochemical impedance spectroscopy (EIS) method in simulated body fluid (SBF). EIS results suggested that the PLA coating enhanced the degradation resistance of the alloy significantly. Increase in the PLA coating thickness was found to increase the degradation resistance, but resulted in poor adhesion. Long-term EIS experiments of the PLA coated samples suggested that their degradation resistance gradually decreased with increase in SBF exposure time. However, the degradation resistance of the PLA coated samples was significantly higher than that of the bare metal even after a 48 h exposure to SBF. - Highlights: Black-Right-Pointing-Pointer Polylactic acid (PLA) was coated on a magnesium-based alloy. Black-Right-Pointing-Pointer PLA coating enhanced the in vitro degradation resistance of the alloy. Black-Right-Pointing-Pointer Increase in the PLA coating thickness improved the alloy degradation resistance. Black-Right-Pointing-Pointer Thin film PLA coating exhibited both good degradation resistance and adhesion.

  14. Polylactic acid coating on a biodegradable magnesium alloy: An in vitro degradation study by electrochemical impedance spectroscopy

    Polylactic acid (PLA) was coated on a biodegradable magnesium alloy, AZ91, using spin coating technique for temporary implant applications. The degradation behaviour of the coated alloy samples was evaluated using electrochemical impedance spectroscopy (EIS) method in simulated body fluid (SBF). EIS results suggested that the PLA coating enhanced the degradation resistance of the alloy significantly. Increase in the PLA coating thickness was found to increase the degradation resistance, but resulted in poor adhesion. Long-term EIS experiments of the PLA coated samples suggested that their degradation resistance gradually decreased with increase in SBF exposure time. However, the degradation resistance of the PLA coated samples was significantly higher than that of the bare metal even after a 48 h exposure to SBF. - Highlights: ► Polylactic acid (PLA) was coated on a magnesium-based alloy. ► PLA coating enhanced the in vitro degradation resistance of the alloy. ► Increase in the PLA coating thickness improved the alloy degradation resistance. ► Thin film PLA coating exhibited both good degradation resistance and adhesion.

  15. Nondestructive Examination (NDE) Detection and Characterization of Degradation Precursors, Technical Progress Report for FY 2012

    Ramuhalli, P.; Meyer, R.M.; Fricke, J.M.; Prowant, M.S.; Coble, J.B.; Griffin, J.W.; Pitman, S.G.; Dahl, M.E.; Kafentzis, T.A.; Roosendaal, T.J.

    2012-09-01

    The overall objective of this project was to investigate the effectiveness of nondestructive examination (NDE) technology in detecting material degradation precursors by initiating and growing cracks in selected materials and using NDE methods to measure crack precursors prior to the onset of cracking. Nuclear reactor components are subject to stresses over time that are not precisely known and that make the life expectancy of components difficult to determine. To prevent future issues with the operation of these plants because of unforeseen failure of components, NDE technology is needed that can be used to identify and quantify precursors to macroscopic degradation of materials. Some of the NDE methods being researched as possible solutions to the precursor detection problem are magnetic Barkhausen noise, nonlinear ultrasonics, acoustic emission, eddy current measurements, and guided wave technology. In FY12, the objective was to complete preliminary assessment of advanced NDE techniques for sensitivity to degradation precursors, using prototypical degradation mechanisms in laboratory-scale measurements. This present document reports on the deliverable that meets the following milestone: M3LW-12OR0402143 – Report detailing an initial demonstration on samples from the crack-initiation tests will be provided (demonstrating acceleration of the work).

  16. Decreased hepatotoxic bile acid composition and altered synthesis in progressive human nonalcoholic fatty liver disease

    Lake, April D. [University of Arizona, Department of Pharmacology and Toxicology, Tucson, AZ 85721 (United States); Novak, Petr [Biology Centre ASCR, Institute of Plant Molecular Biology, Ceske Budejovice 37001 (Czech Republic); Shipkova, Petia; Aranibar, Nelly; Robertson, Donald; Reily, Michael D. [Pharmaceutical Candidate Optimization, Bristol-Myers Squibb Co., Princeton, NJ 08543 (United States); Lu, Zhenqiang [The Arizona Statistical Consulting Laboratory, University of Arizona, Tucson, AZ 85721 (United States); Lehman-McKeeman, Lois D. [Pharmaceutical Candidate Optimization, Bristol-Myers Squibb Co., Princeton, NJ 08543 (United States); Cherrington, Nathan J., E-mail: cherrington@pharmacy.arizona.edu [University of Arizona, Department of Pharmacology and Toxicology, Tucson, AZ 85721 (United States)

    2013-04-15

    Bile acids (BAs) have many physiological roles and exhibit both toxic and protective influences within the liver. Alterations in the BA profile may be the result of disease induced liver injury. Nonalcoholic fatty liver disease (NAFLD) is a prevalent form of chronic liver disease characterized by the pathophysiological progression from simple steatosis to nonalcoholic steatohepatitis (NASH). The hypothesis of this study is that the ‘classical’ (neutral) and ‘alternative’ (acidic) BA synthesis pathways are altered together with hepatic BA composition during progression of human NAFLD. This study employed the use of transcriptomic and metabolomic assays to study the hepatic toxicologic BA profile in progressive human NAFLD. Individual human liver samples diagnosed as normal, steatosis, and NASH were utilized in the assays. The transcriptomic analysis of 70 BA genes revealed an enrichment of downregulated BA metabolism and transcription factor/receptor genes in livers diagnosed as NASH. Increased mRNA expression of BAAT and CYP7B1 was observed in contrast to decreased CYP8B1 expression in NASH samples. The BA metabolomic profile of NASH livers exhibited an increase in taurine together with elevated levels of conjugated BA species, taurocholic acid (TCA) and taurodeoxycholic acid (TDCA). Conversely, cholic acid (CA) and glycodeoxycholic acid (GDCA) were decreased in NASH liver. These findings reveal a potential shift toward the alternative pathway of BA synthesis during NASH, mediated by increased mRNA and protein expression of CYP7B1. Overall, the transcriptomic changes of BA synthesis pathway enzymes together with altered hepatic BA composition signify an attempt by the liver to reduce hepatotoxicity during disease progression to NASH. - Highlights: ► Altered hepatic bile acid composition is observed in progressive NAFLD. ► Bile acid synthesis enzymes are transcriptionally altered in NASH livers. ► Increased levels of taurine and conjugated bile acids

  17. Decreased hepatotoxic bile acid composition and altered synthesis in progressive human nonalcoholic fatty liver disease

    Bile acids (BAs) have many physiological roles and exhibit both toxic and protective influences within the liver. Alterations in the BA profile may be the result of disease induced liver injury. Nonalcoholic fatty liver disease (NAFLD) is a prevalent form of chronic liver disease characterized by the pathophysiological progression from simple steatosis to nonalcoholic steatohepatitis (NASH). The hypothesis of this study is that the ‘classical’ (neutral) and ‘alternative’ (acidic) BA synthesis pathways are altered together with hepatic BA composition during progression of human NAFLD. This study employed the use of transcriptomic and metabolomic assays to study the hepatic toxicologic BA profile in progressive human NAFLD. Individual human liver samples diagnosed as normal, steatosis, and NASH were utilized in the assays. The transcriptomic analysis of 70 BA genes revealed an enrichment of downregulated BA metabolism and transcription factor/receptor genes in livers diagnosed as NASH. Increased mRNA expression of BAAT and CYP7B1 was observed in contrast to decreased CYP8B1 expression in NASH samples. The BA metabolomic profile of NASH livers exhibited an increase in taurine together with elevated levels of conjugated BA species, taurocholic acid (TCA) and taurodeoxycholic acid (TDCA). Conversely, cholic acid (CA) and glycodeoxycholic acid (GDCA) were decreased in NASH liver. These findings reveal a potential shift toward the alternative pathway of BA synthesis during NASH, mediated by increased mRNA and protein expression of CYP7B1. Overall, the transcriptomic changes of BA synthesis pathway enzymes together with altered hepatic BA composition signify an attempt by the liver to reduce hepatotoxicity during disease progression to NASH. - Highlights: ► Altered hepatic bile acid composition is observed in progressive NAFLD. ► Bile acid synthesis enzymes are transcriptionally altered in NASH livers. ► Increased levels of taurine and conjugated bile acids

  18. Cathepsin D-mediated yolk protein degradation is blocked by acid phosphatase inhibitors.

    Fialho, Eliane; Nakamura, Angelica; Juliano, Luiz; Masuda, Hatisaburo; Silva-Neto, Mário A C

    2005-04-15

    Vitellin (VT) is a lipoglycophosphoprotein stored inside the eggs of every oviparous organism during oogenesis. In the blood-sucking bug Rhodnius prolixus, VT is deposited inside growing oocytes together with two acid hydrolases: acid phosphatase (AP) and cathepsin D (CD). Egg fertilization triggers AP activity and VT proteolysis in vivo [Insect Biochem. Mol. Biol. 2002 (32) 847]. Here, we show that CD is the main protease targeting VT proteolysis during egg development. CD activity in total egg homogenates is blocked by the classical aspartyl protease inhibitor, pepstatin A. Surprisingly, AP inhibitors such as NaF, Na+/K+ tartrate, and inorganic phosphate also block VT proteolysis, whereas this effect is not observed when tyrosine phosphatase inhibitors such as vanadate and phenylarsine oxide or an inhibitor of alkaline phosphatases such as levamisole are used in a VT proteolysis assay. NaF concentrations that block isolated AP activity do not affect the activity of partially purified CD. Therefore, a specific repressor of VT proteolysis must be dephosphorylated by AP in vivo. In conclusion, these results demonstrate for the first time that acid hydrolases act cooperatively to promote yolk degradation during egg development in arthropods. PMID:15797237

  19. D-Galacturonic Acid: A Highly Reactive Compound in Nonenzymatic Browning. 2. Formation of Amino-Specific Degradation Products.

    Wegener, Steffen; Bornik, Maria-Anna; Kroh, Lothar W

    2015-07-22

    Thermal treatment of aqueous solutions of D-galacturonic acid and L-alanine at pH 3, 5, and 8 led to rapid and more intensive nonenzymatic browning reactions compared to similar solutions of other uronic acids and to Maillard reactions of reducing sugars. The hemiacetal ring structures of uronic acids had a high impact on browning behavior and reaction pathways. Besides reductic acid (1,2-dihydroxy-2-cyclopenten-1-one), 4,5-dihydroxy-2-cyclopenten-1-one (DHCP), furan-2-carboxaldehyde, and norfuraneol (4-hydroxy-5-methyl-3-(2H)-furanone) could be detected as typical products of nonenzymatic uronic acid browning reactions. 2-(2-Formyl-1H-pyrrole-1-yl)propanoic acid (FPA) and 1-(1-carboxyethyl)-3-hydroxypyridin-1-ium (HPA) were identified as specific reaction products of uronic acids with amine participation like l-alanine. In contrast, the structurally related D-galacturonic acid methyl ester showed less browning activity and degradation under equal reaction conditions. Pectin-specific degradation products such as 5-formyl-2-furanoic acid and 2-furanoic acid were found but could not be verified for d-galacturonic acid monomers alone. PMID:26111613

  20. Isonicotinic acid-ligated cobalt (II phthalocyanine-modified titania as photocatalyst for benzene degradation via fluorescent lamp

    Joey Andrew A. Valinton

    2016-06-01

    Full Text Available The utilization of bis(isonicotinic acidphthalocyaninatocobalt (II [CoPc(isa2] incorporated on TiO2 has been studied as a photocatalyst to degrade benzene vapor under fluorescent lamp (indoor light conditions. The photocatalytic activity of [CoPc(isa2]-TiO2 compared to TiO2 showed an increase in the extent of degradation. The axial isonicotinic acid ligand attached to CoPc improved the degradation rate of benzene as compared with unligated CoPc-TiO2 which may be attributed to the enhancement of electronic structure in the complex due to the additional isonicotinic acid ligand and its possible attachment to the TiO2 surface through the carboxylic acid moiety. Therefore, covalently-linked CoPc(isa2 to TiO2 can enhance the extent of photodegradation of benzene and other common volatile organic compounds under indoor lighting conditions.

  1. Compostability of Co-Extruded Starch/Poly(Lactic Acid Polymeric Material Degradation in an Activated Inert Solid Medium

    Alain Copinet

    2009-07-01

    Full Text Available The aim of this work was to estimate the biodegradation of a co-extruded starch/poly(lactic acid polymeric material using a vermiculite based inert solid medium which could simulate compost medium and enable us to achieve complete carbon balances. At the end of the test the mineralisation rate was compared to those obtained for co-extruded starch/poly(lactic acid polymeric material degradation in compost. It was shown that the mineralisation rate after 45 days of degradation was similar in activated vermiculite medium to the one in compost. A protocol for both extraction and quantification of the carbon included in the different degradation by-products was proposed and the carbon balance of the polymer degradation was followed during the test with a satisfactory accuracy. As the non-degraded PLA and starch material had been retrieved during the test, the evolution of the glass transition temperature and the molecular weight of PLA could be followed. A two-step degradation mechanism was highlighted in inert solid medium, showing the fundamental role of abiotic reactions for PLA degradation in compost.

  2. Thermal degradation of biopolymer binders: the example of starch-poly(acrylic acid

    B. Grabowska

    2010-01-01

    Full Text Available To characterise a polymer, it is of fundamental importance to determine its parameters, like the temperatures of destruction, vitrification, melting point, specific mass losses or polymorphic transformations, which frequently determine the quality of the product and its applications. Thermal analyses were conducted of samples of a biopolymer binder: a starch-poly(acrylic acid composition and a moulding sand with a biopolymer binder previously hardened with microwaves. In order to determine the thermal stability of the examined samples by determining the destruction temperature and the thermal effects of transformations taking place during heating, FTIR spectroscopy and thermal analysis (DSC, DTG, TG methods were used. In addition, volatile products of degradation were analysed using the thermogravimetry (TG method coupled online with mass spectrometry (MS. These examinations were also aimed at identifying the changes that can take place in the moulding sand when it comes into contact with liquid metal.

  3. Population of Humic Acid Degrading Microorganisms in Andosols under Different Vegetation Types and Grassland Management Regimens.

    Yanagi, Yukiko; Yoda, Kaori; Ogura, Kazuhiko; Fujitake, Nobuhide

    2008-01-01

    To examine the effect of vegetation type and grassland management regimen on the distribution of humus-degrading microorganisms, populations of humic acid-degrading (HAD) bacteria and fungi at three Andosol sites were investigated using the dilution plate method. Each site had three different vegetation types (Eulalia grassland, bamboo grassland, and coniferous plantations). Among the six grassland sites, two were maintained by burning and the others by cutting. HAD microorganisms were found in all soil samples. Low densities and small percentages of HAD bacteria were detected with no significant differences in the number of bacteria found between different vegetation types and grasslands managed in different ways. In contrast, the densities and percentages of HAD fungi differed according to vegetation type and management regimen. Specifically, the percentages of HAD fungi were significantly higher for burned grasslands. At burned sites, the numbers and percentages of HAD bacteria remained at a consistently low level, and no distinct seasonal changes were observed. In contrast, marked seasonal fluctuations in HAD fungi were detected. The percentages of these fungi remained relatively high between April and December. These fluctuations are likely due to the effects of burning on soil microorganisms. PMID:21558687

  4. Influence of neutral and charged species on the plasma degradation of the stearic acid

    Euclides Alexandre Bernardelli

    2013-04-01

    Full Text Available In this work, stearic acid (SA was degraded in an Ar-O2and Ar-H2post-discharge environment created by a plasma reactor with a microwave source and in an Ar, Ar-H2and Ar-O2DC (Direct Current discharge environment created in a cathode-anode confined system. The afterglow region is useful for understanding the role of the chemically active species (O, O2, H and H2. In contrast, the discharge region allows the observation of the effects of chemically active species, charged species (ions and electrons and photons. The influence of these species on the grafting and etching of SA was evaluated by measuring the mass variation, mass variation rate and chemical composition. The results showed that when only chemically active oxygen species are present, the SA is preferentially grafted. However, when both photons and charged species are present, the SA is more efficiently etched. When the Ar-H2and Ar environments are utilized; the SA is not efficiently degraded.

  5. Hyaluronic acid binding, endocytosis and degradation by sinusoidal liver endothelial cells

    The binding, endocytosis, and degradation of 125I-hyaluronic acid (125I-HA) by liver endothelial cells (LEC) was studied under several conditions. The dissociation of receptor-bound 125I-HA was rapid, with a half time of ∼31 min and a Koff of 6.3 x 10-4/sec. A large reversible increase in 125I-HA binding to LEC at pH 5.0 was due to an increase in the observed affinity of the binding interaction. Pronase digestion suggested the protein nature of the receptor and the intracellular location of the digitonin exposed binding activity. Binding and endocytosis occur in the presence of 10 mM EGTA indicating that divalent cations are not required for receptor function. To study the degradation of 125I-HA by LEC, a cetylpyridinium chloride (CPC) precipitation assay was characterized. The minimum HA length required for precipitation was elucidated. The fate of the LEC HA receptor after endocytosis was examined

  6. Hyaluronic acid binding, endocytosis and degradation by sinusoidal liver endothelial cells

    McGary, C.T.

    1988-01-01

    The binding, endocytosis, and degradation of {sup 125}I-hyaluronic acid ({sup 125}I-HA) by liver endothelial cells (LEC) was studied under several conditions. The dissociation of receptor-bound {sup 125}I-HA was rapid, with a half time of {approx}31 min and a K{sub off} of 6.3 {times} 10{sup {minus}4}/sec. A large reversible increase in {sup 125}I-HA binding to LEC at pH 5.0 was due to an increase in the observed affinity of the binding interaction. Pronase digestion suggested the protein nature of the receptor and the intracellular location of the digitonin exposed binding activity. Binding and endocytosis occur in the presence of 10 mM EGTA indicating that divalent cations are not required for receptor function. To study the degradation of {sup 125}I-HA by LEC, a cetylpyridinium chloride (CPC) precipitation assay was characterized. The minimum HA length required for precipitation was elucidated. The fate of the LEC HA receptor after endocytosis was examined.

  7. Degradable biocomposite of nano calcium- deficient hydroxyapatite-multi(amino acid copolymer

    Li XD

    2012-03-01

    Full Text Available Hong Li1, Min Gong1, Aiping Yang1, Jian Ma2, Xiangde Li3, Yonggang Yan11School of Physical Science and Technology, Sichuan University, Chengdu People’s Republic of China; 2Hospital of Stomatology, Tongji University, ShanghaiPeople’s Republic of China; 3Key Laboratory for Ultrafine Materials of Ministry of Education, East China University of Science and Technology, Shanghai, People’s Republic of ChinaBackground and methods: A nano calcium-deficient hydroxyapatite (n-CDHA-multi(amino acid copolymer (MAC composite bone substitute biomaterial was prepared using an in situ polymerization method. The composition, structure, and compressive strength of the composite was characterized, and the in vitro degradability in phosphate-buffered solution and preliminary cell responses to the composite were investigated.Results: The composite comprised n-CDHA and an amide linkage copolymer. The compressive strength of the composite was in the range of 88–129 MPa, varying with the amount of n-CDHA in the MAC (ranging from 10 wt% to 50 wt%. Weight loss from the composite increased (from 32.2 wt% to 44.3 wt% with increasing n-CDHA content (from 10 wt% to 40 wt% in the MAC after the composite was soaked in phosphate-buffered solution for 12 weeks. The pH of the soaking medium varied from 6.9 to 7.5. MG-63 cells with an osteogenic phenotype were well adhered and spread on the composite surface. Viability and differentiation increased with time, indicating that the composite had no negative effects on MG-63 cells.Conclusion: The n-CDHA-MAC composite had good cytocompatibility and has potential to be used as a bone substitute.Keywords: calcium deficient hydroxyapatite, multi(amino acid copolymer, biocomposite, degradability, cytocompatibility

  8. Crystal structure of phenylacetic acid degradation protein PaaG from Thermus thermophilus HB8.

    Kichise, Tomoyasu; Hisano, Tamao; Takeda, Kazuki; Miki, Kunio

    2009-09-01

    Microbial degradation of phenylacetic acid proceeds via the hybrid pathway that includes formation of a coenzyme A thioester, ring hydroxylation, non-oxygenolytic ring opening, and beta-oxidation-like reactions. A phenylacetic acid degradation protein PaaG is a member of the crotonase superfamily, and is a candidate non-oxygenolytic ring-opening enzyme. The crystal structure of PaaG from Thermus thermophilus HB8 was determined at a resolution of 1.85 A. PaaG consists of three identical subunits related by local three-fold symmetry. The monomer is comprised of a spiral and a helical domain with a fold characteristic of the crotonase superfamily. A putative active site residue, Asp136, is situated in an active site cavity and surrounded by several hydrophobic and hydrophilic residues. The active site cavity is sufficiently large to accommodate a ring substrate. Two conformations are observed for helix H2 located adjacent to the active site. Helix H2 is kinked at Asn81 in two subunits, whereas it is kinked at Leu77 in the other subunit, and the side chain of Tyr80 is closer to Asp136. This indicates that catalytic reaction of PaaG may proceed with large conformational changes at the active site. Asp136 is the only conserved polar residue in the active site. It is located at the same position as those of 4-chlorobenzoyl-CoA dehalogenase and peroxisomal Delta(3),Delta(2)-enoyl-CoA isomerase, indicating that PaaG may undergo isomerization or a ring-opening reaction via a Delta(3),Delta(2)-enoyl-CoA isomerase-like mechanism. PMID:19452559

  9. Clostridium sticklandii, a specialist in amino acid degradation:revisiting its metabolism through its genome sequence

    Pelletier Eric

    2010-10-01

    Full Text Available Abstract Background Clostridium sticklandii belongs to a cluster of non-pathogenic proteolytic clostridia which utilize amino acids as carbon and energy sources. Isolated by T.C. Stadtman in 1954, it has been generally regarded as a "gold mine" for novel biochemical reactions and is used as a model organism for studying metabolic aspects such as the Stickland reaction, coenzyme-B12- and selenium-dependent reactions of amino acids. With the goal of revisiting its carbon, nitrogen, and energy metabolism, and comparing studies with other clostridia, its genome has been sequenced and analyzed. Results C. sticklandii is one of the best biochemically studied proteolytic clostridial species. Useful additional information has been obtained from the sequencing and annotation of its genome, which is presented in this paper. Besides, experimental procedures reveal that C. sticklandii degrades amino acids in a preferential and sequential way. The organism prefers threonine, arginine, serine, cysteine, proline, and glycine, whereas glutamate, aspartate and alanine are excreted. Energy conservation is primarily obtained by substrate-level phosphorylation in fermentative pathways. The reactions catalyzed by different ferredoxin oxidoreductases and the exergonic NADH-dependent reduction of crotonyl-CoA point to a possible chemiosmotic energy conservation via the Rnf complex. C. sticklandii possesses both the F-type and V-type ATPases. The discovery of an as yet unrecognized selenoprotein in the D-proline reductase operon suggests a more detailed mechanism for NADH-dependent D-proline reduction. A rather unusual metabolic feature is the presence of genes for all the enzymes involved in two different CO2-fixation pathways: C. sticklandii harbours both the glycine synthase/glycine reductase and the Wood-Ljungdahl pathways. This unusual pathway combination has retrospectively been observed in only four other sequenced microorganisms. Conclusions Analysis of the C

  10. Rumen Degradability and Small Intestinal Digestibility of the Amino Acids in Four Protein Supplements.

    Wang, Y; Jin, L; Wen, Q N; Kopparapu, N K; Liu, J; Liu, X L; Zhang, Y G

    2016-02-01

    The supplementation of livestock feed with animal protein is a present cause for public concern, and plant protein shortages have become increasingly prominent in China. This conflict may be resolved by fully utilizing currently available sources of plant protein. We estimated the rumen degradability and the small intestinal digestibility of the amino acids (AA) in rapeseed meal (RSM), soybean meal (SBM), sunflower seed meal (SFM) and sesame meal (SSM) using the mobile nylon bag method to determine the absorbable AA content of these protein supplements as a guide towards dietary formulations for the dairy industry. Overall, this study aimed to utilize protein supplements effectively to guide dietary formulations to increase milk yield and save plant protein resources. To this end, we studied four cows with a permanent rumen fistula and duodenal T-shape fistula in a 4×4 Latin square experimental design. The results showed that the total small intestine absorbable amino acids and small intestine absorbable essential amino acids were higher in the SBM (26.34% and 13.11% dry matter [DM], respectively) than in the SFM (13.97% and 6.89% DM, respectively). The small intestine absorbable Lys contents of the SFM, SSM, RSM and SBM were 0.86%, 0.88%, 1.43%, and 2.12% (DM basis), respectively, and the absorbable Met contents of these meals were 0.28%, 1.03%, 0.52%, and 0.47% (DM basis), respectively. Among the examined food sources, the milk protein score of the SBM (0.181) was highest followed by those of the RSM (0.136), SSM (0.108) and SFM (0.106). The absorbable amino acid contents of the protein supplements accurately reflected protein availability, which is an important indicator of the balance of feed formulation. Therefore, a database detailing the absorbable AA should be established. PMID:26732449

  11. Effect of Six Feed Supplements on Ruminal Degradation Characteristics and Amino Acid Profile of Sheep

    Demba B. Jallow

    2011-10-01

    Full Text Available The objective of this study was to determine the influence of degradation characteristics of six feed supplements on ruminal volatile fatty acid and amino acid production and profile using three ruminally cannulated male sheep. The sheep were fed a concentrate to forage ratio of 35:65. The supplements came from Soybean Meal (SBM, Corn Meal (CM, Meat and Bone Meal (MBM, Feather Meal (FtM, Blood Meal (BM, and distillers Dried Gain with Soluble (DDGs. Sheep were fed at 6 h interval for 42 days. Ruminal parameters such as pH, NH4+, temperature, NO3-, and Volatile Fatty Acids (VFA were measured over a 12 h period after feeding. Concentrations of pH, NH4+, and NO3- showed significant difference (p<0.001 across all dietary treatments. Sheep fed BM had higher pH (6.64 vs. 5.81, NH4+ (262.31 vs. 1.95 ppm, and NO3- (559.71 vs. 77.40 ppm values than did those fed CM whereas FtM showed intermediate values. The C2/ (C3+C4 ratio of the major VFA showed a significant difference (p<0.001. Ruminal profile (% of the sum of amino acids measured was similar among feeds, except Asp, isoleucine, lysine, and proline, respectively. Specific first limiting AA was methionine for SBM while lysine was co-limiting for FtM and DDGs. In general, ruminal parameters were clearly influenced by dietary treatments, with a lower ruminal pH and a higher NH4+ in BM than CM. Overall, the concentration of both total EAA and NEAA were similar among feeds, but numerically SBM had more EAA concentrations followed by CM, MBM, DDGs, BM, and FtM.

  12. Structural Characterization of the Degradation Products of a Minor Natural Sweet Diterpene Glycoside Rebaudioside M under Acidic Conditions

    Indra Prakash

    2014-01-01

    Full Text Available Degradation of rebaudioside M, a minor sweet component of Stevia rebaudiana Bertoni, under conditions that simulated extreme pH and temperature conditions has been studied. Thus, rebaudioside M was treated with 0.1 M phosphoric acid solution (pH 2.0 and 80 °C temperature for 24 h. Experimental results indicated that rebaudioside M under low pH and higher temperature yielded three minor degradation compounds, whose structural characterization was performed on the basis of 1D (1H-, 13C- & 2D (COSY, HSQC, HMBC NMR, HRMS, MS/MS spectral data as well as enzymatic and acid hydrolysis studies.

  13. Structural characterization of the degradation products of a minor natural sweet diterpene glycoside Rebaudioside M under acidic conditions.

    Prakash, Indra; Chaturvedula, Venkata Sai Prakash; Markosyan, Avetik

    2014-01-01

    Degradation of rebaudioside M, a minor sweet component of Stevia rebaudiana Bertoni, under conditions that simulated extreme pH and temperature conditions has been studied. Thus, rebaudioside M was treated with 0.1 M phosphoric acid solution (pH 2.0) and 80 °C temperature for 24 h. Experimental results indicated that rebaudioside M under low pH and higher temperature yielded three minor degradation compounds, whose structural characterization was performed on the basis of 1D (1H-, 13C-) & 2D (COSY, HSQC, HMBC) NMR, HRMS, MS/MS spectral data as well as enzymatic and acid hydrolysis studies. PMID:24424316

  14. Biomechanical features of Poly-D,L-lactic acid (PDLLA) rods through the degradation in vitro and in vivo

    2006-01-01

    Objective:To observe the changing of biomechanical features during the degradation course of poly-D,L-lactic acid (PDLLA) rods in vivo and in vitro and to evaluate its value as an internal fixation material. Methods :PDLLA rods were emerged into PBS simultaneous body fluid with constant temperature of 37C and the rods were embedded into muscle tissue of 20 rabbits for degradation in vitro and in vivo . The rods were taken out in 2, 4, 6, 8 and 12 weeks. Biomechanical features of bending, shearing and axial compression strength, rigidity and elastic modulus were observed during the degradation course. Statistical method was used to test the changes of biomechanical parameters. Results: (1)There was similar changes of bending, compressive, shearing strength and bending, compressive and shearing rigidity of the PDLLA rods between in vivo and in vitro. (2)Bending, compressive, shearing strength decreased 33%,18 % and 43 % respectively within the first stage of the degradation, and after 6 weeks of degradation, they decreased slowly. (3)Elastic modulus, bending, compressive and shearing rigiditydecreased sharply during the 6 weeks of degradation, with a drop of 22%, 39% and 30%00 respectively, and after 8 weeks, they decreased slowly. Even after 12 weeks of degradation, the strength of the rods was still higher than that of sponge bone. Conclusion: During the degradation of the material, the strength and rigidity of PDLLA rods can meet the need of fracture fixation of cancellous bones.

  15. Evaluation of physical and mechanical properties of porous poly (ethylene glycol-co-(L-lactic acid hydrogels during degradation.

    Yu-Chieh Chiu

    Full Text Available Porous hydrogels of poly(ethylene glycol (PEG have been shown to facilitate vascularized tissue formation. However, PEG hydrogels exhibit limited degradation under physiological conditions which hinders their ultimate applicability for tissue engineering therapies. Introduction of poly(L-lactic acid (PLLA chains into the PEG backbone results in copolymers that exhibit degradation via hydrolysis that can be controlled, in part, by the copolymer conditions. In this study, porous, PEG-PLLA hydrogels were generated by solvent casting/particulate leaching and photopolymerization. The influence of polymer conditions on hydrogel architecture, degradation and mechanical properties was investigated. Autofluorescence exhibited by the hydrogels allowed for three-dimensional, non-destructive monitoring of hydrogel structure under fully swelled conditions. The initial pore size depended on particulate size but not polymer concentration, while degradation time was dependent on polymer concentration. Compressive modulus was a function of polymer concentration and decreased as the hydrogels degraded. Interestingly, pore size did not vary during degradation contrary to what has been observed in other polymer systems. These results provide a technique for generating porous, degradable PEG-PLLA hydrogels and insight into how the degradation, structure, and mechanical properties depend on synthesis conditions.

  16. Degradation of the Plant Defense Signal Salicylic Acid Protects Ralstonia solanacearum from Toxicity and Enhances Virulence on Tobacco

    Lowe-Power, Tiffany M.; Jacobs, Jonathan M.; Ailloud, Florent; Fochs, Brianna; Prior, Philippe

    2016-01-01

    ABSTRACT Plants use the signaling molecule salicylic acid (SA) to trigger defenses against diverse pathogens, including the bacterial wilt pathogen Ralstonia solanacearum. SA can also inhibit microbial growth. Most sequenced strains of the heterogeneous R. solanacearum species complex can degrade SA via gentisic acid to pyruvate and fumarate. R. solanacearum strain GMI1000 expresses this SA degradation pathway during tomato pathogenesis. Transcriptional analysis revealed that subinhibitory SA levels induced expression of the SA degradation pathway, toxin efflux pumps, and some general stress responses. Interestingly, SA treatment repressed expression of virulence factors, including the type III secretion system, suggesting that this pathogen may suppress virulence functions when stressed. A GMI1000 mutant lacking SA degradation activity was much more susceptible to SA toxicity but retained the wild-type colonization ability and virulence on tomato. This may be because SA is less important than gentisic acid in tomato defense signaling. However, another host, tobacco, responds strongly to SA. To test the hypothesis that SA degradation contributes to virulence on tobacco, we measured the effect of adding this pathway to the tobacco-pathogenic R. solanacearum strain K60, which lacks SA degradation genes. Ectopic addition of the GMI1000 SA degradation locus, including adjacent genes encoding two porins and a LysR-type transcriptional regulator, significantly increased the virulence of strain K60 on tobacco. Together, these results suggest that R. solanacearum degrades plant SA to protect itself from inhibitory levels of this compound and also to enhance its virulence on plant hosts like tobacco that use SA as a defense signal molecule. PMID:27329752

  17. In Situ Degradation of Chitosan-Polygalacturonic Acid/Hydroxyapatite Nano composites in Cell Culture Media

    The molecular and mechanical characteristics of in situ degradation behavior of chitosan-polygalacturonic acid/hydroxyapatite (Chi-PgA-HAP) nano composite films is investigated using Fourier Transform Infrared spectroscopy (FTIR), Atomic Force Microscopy (AFM), and modulus mapping techniques for up to 48 days of soaking in cell culture media. The surface molecular structure of media-soaked samples changes over the course of 48 days of soaking, as indicated by significant changes in phosphate vibrations (1200-900cm-1) indicating apatite formation. Chitosan-Polygalacturonic acid polyelectrolyte complexes (PECs) govern structural integrity of Chi-PgA-HAP nano composites and FTIR spectra indicate that PECs remain intact until 48 days of soaking. In situ AFM experiments on media-soaked samples indicate that soaking results in a change in topography and swelling proceeds differently at the initial soaking periods of about 8 days than for longer soaking. In situ modulus mapping experiments are done on soaked samples by probing 13 nm of surface indicating elastic moduli of 4 GPa resulting from proteins adsorbed on Chi-PgA-HAP nano composites. The elastic modulus decreases by 2 GPa over a long exposure to cell culture media (48 days). Thus, as water enters the Chi-PgA-HAP sample, surface molecular interactions in Chi-PgA-HAP structure occur that result in swelling, causing small changes in nano scale mechanical properties.

  18. Gastric-resistant isoniazid pellets reduced degradation of rifampicin in acidic medium

    Fátima Duarte Freire

    2014-12-01

    Full Text Available Isoniazid and rifampicin are considered the first-line medication for preventing and treating tuberculosis. Rifampicin is degraded in the stomach acidic environment, especially when combined with isoniazid, factor contributing to treatment failure. In this study, gastric-resistant isoniazid pellets were obtained to physical contact of this drug with rifampicin and to bypass the stomach´s acidic environment. The pellets were fabricated using the extrusion-spheronization technique. The coating process was conducted in a fluid spray coater using Acrycoat L 100(r solution as the coating agent. The pellets obtained were submitted to a dissolution test in HCl 0.1 N and phosphate buffer media. The results indicated that optimum gastric-resistance was only attained with the highest amount of coating material, with isoniazid almost fully released in phosphate buffer. The amount of rifampicin released from its mixture with non-coated isoniazid pellets in HCl 0.1 N was less than that released from its mixture with the enteric-coated pellets. Acrycoat L 100(r was shown to be an effective enteric/gastric-resistant coating since the stability of rifampicin appeared to be enhanced when physical contact of this drug with isoniazid was prevented at low pH.

  19. Contact sensitizers induce skin inflammation via ROS production and hyaluronic acid degradation.

    Philipp R Esser

    Full Text Available BACKGROUND: Allergic contact dermatitis (ACD represents a severe health problem with increasing worldwide prevalence. It is a T cell-mediated skin disease induced by protein-reactive organic and inorganic chemicals. A key feature of contact allergens is their ability to trigger an innate immune response that leads to skin inflammation. Previous evidence from the mouse contact hypersensitivity (CHS model suggests a role for endogenous activators of innate immune signaling. Here, we analyzed the role of contact sensitizer induced ROS production and concomitant changes in hyaluronic acid metabolism on CHS responses. METHODOLOGY/PRINCIPAL FINDINGS: We analyzed in vitro and in vivo ROS production using fluorescent ROS detection reagents. HA fragmentation was determined by gel electrophoresis. The influence of blocking ROS production and HA degradation by antioxidants, hyaluronidase-inhibitor or p38 MAPK inhibitor was analyzed in the murine CHS model. Here, we demonstrate that organic contact sensitizers induce production of reactive oxygen species (ROS and a concomitant breakdown of the extracellular matrix (ECM component hyaluronic acid (HA to pro-inflammatory low molecular weight fragments in the skin. Importantly, inhibition of either ROS-mediated or enzymatic HA breakdown prevents sensitization as well as elicitation of CHS. CONCLUSIONS/SIGNIFICANCE: These data identify an indirect mechanism of contact sensitizer induced innate inflammatory signaling involving the breakdown of the ECM and generation of endogenous danger signals. Our findings suggest a beneficial role for anti-oxidants and hyaluronidase inhibitors in prevention and treatment of ACD.

  20. Acute Acidification of Stratum Corneum Membrane Domains Using Polyhydroxyl Acids Improves Lipid Processing and Inhibits Degradation of Corneodesmosomes

    Hachem, Jean-Pierre; Roelandt, Truus; Schürer, Nanna; Pu, Xu; Fluhr, Joachim; Giddelo, Christina; Man, Mao-Qiang; Crumrine, Debra; Roseeuw, Diane; Feingold, Kenneth R.; Mauro, Theodora; Elias, Peter M.

    2009-01-01

    Neutralization of the normally acidic stratum corneum (SC) has deleterious consequences for permeability barrier homeostasis and SC integrity/cohesion attributable to serine proteases (SPs) activation leading to deactivation/degradation of lipid-processing enzymes and corneodesmosomes (CD). As an elevated pH compromises SC structure and function, we asked here whether SC hyperacidification would improve the structure and function. We lowered the pH of mouse SC using two polyhydroxyl acids (PH...

  1. Oxidative degradation of ion-exchange resins in acid medium. Vol. 3

    Volume reduction of spent ion-exchange resins used in nuclear facilities receive increasing importance due to the increase in storage cost, unstable physical and chemical properties and their relatively high specific activity (in some cases up to 1 Ci per liter). The present study is part of research program on the treatment and immobilization of radioactive spent ion-exchange resins simulate; hydrogen peroxide was used for the oxidative degradation of spent ion-exchange resins simulate in sulphuric acid medium. Five liters ring digester developed in Karlsruhe nuclear research center-(KFK)- in germany was the chosen option to perform the oxidation process. The work reported focused on the kinetics and mechanism of the oxidation process. Heating the organic resins in sulphuric acid results in its carbonization and partial oxidation of only 1.7% of the carbon added. Results show that the oxidation reaction is a relatively slow process of first order with K value in the order of 10-4 min-1, and the main oxidation product was carbon dioxide. The production of carbon oxide in the off gas stream increased sharply by the addition of hydrogen peroxide to the hot sulphuric acid-resin mixture. The results obtained show that more than 97% of the carbon added was oxidized to carbon dioxide and carbon monoxide. The rate constant value (K) of this reaction was calculated to be (1.69±0.13) x 10-2 min-1. The results of gas chromatographic analysis indicate that no significant amounts of hazardous organic materials were detected in the off-gas streams. 6 figs., 4 tabs

  2. Uranium (UO22+) retention property of degraded n-dodecane by acidic radiolysis in the purex process

    Radiation effects on the uranium retention property of degraded n-dodecane by acidic radiolysis in the Purex process were studied. The absorbed dose of n-dodecane varied from 24.04 to 2 403.69 kGy (5 to 500 Wh/dm3). When the absorbed dose exceeded 48.07 kGy (10 Wh/dm3), the uranium (UO22+) was retained in degraded n-dodecane even without TBP as extractant. An empirical correlation of the uranium retention was also derived. This correlation is a very effective one because it can especially be used for the prediction of the amount of retained uranium in the degraded n-dodecane. Data obtained through this work should be useful for the process design under solvent degradation conditions in nuclear fuel processing facilities especially reused solvent. (author)

  3. Synthesis and in vitro bio degradation of poly(ethylene adipate- co-D,L-lactic acid copolymers (PLEA

    Bakouri Hichem

    2014-09-01

    Full Text Available The present research mainly focused on the synthesis and study of bio degradation of poly (ethylene adipate-co-D,L-lactic acid. PLEA were prepared via ring opening polymerization from D,L-lactide and poly(ethylene adipate. PLEA was characterized by 1H NMR spectra and DSC; results showed that those properties showed high dependence on its composition.In vitro degradation behaviors of PLEA have been systematically investigated up to 12 weeks in phosphate buffer saline solution at 37 °C. The weight and polymer molecular weight were measured as a function of degradation time. Bacterial degradation was completed by investigating the physico-chemical properties using spectroscopy FTIR and DSC.

  4. Degradation of Poly(L-Lactic Acid) and Bio-Composites by Alkaline Medium under Various Temperatures

    Ribbons of poly(lactic acid) (PLA) and PLA containing 10 or 25 % Osage orange (OO) biocomposites of various sized heartwood particles were exposed to non-composting soil conditions either outdoors or in a greenhouse. No appreciable degradation was evident even after 208 day treatments. An artifici...

  5. Stability-Indicating Methods for the Determination of Gemifloxacin in Presence of its Acid Degradation Product(s

    Ezzat M. Abdel-Moety

    2015-05-01

    Full Text Available Brilliant, valid and simple five UV spectrophotometric stability indicating techniques are adopted for the determination of Gemifloxacin (GEM in presence of its acid degradation products over a concentration range of 2-12 μg mL-1. The first method is an application of the first derivative (1D spectrophotometry, that allows the determination of GEM without interference of its acid degradation products at zero crossing wavelength (254.6 nm. The second method depends on the first-derivative of the ratio spectra spectrophotometry (1DD for determination of GEM in presence of its acid degradation products at a maximum of 273.0 nm and a minimum of 284.0 nm, While the third dual wavelength method offers a superior stability indicating procedures for the determination of GEM in the zero order spectra at the wavelength pair of 271.8 nm and 325.0 nm. The fourth method is the ratio difference one, with the advantages of minimal data processing and wide range of application. It is applied for the analysis of intact drug in presence of its acid degradation products by measuring the difference in the peak amplitude at the ratio spectra at 355.0 nm and 270.0 nm. The last method is based on the quantification of GEM through the bivariate calibration at 255.0 nm and 277.0 nm by adopting simple mathematic algorithm that provides simplicity and rapidity

  6. Naphthenic acids degradation and toxicity mitigation in tailings wastewater systems and aquatic environments: a review.

    Kannel, Prakash R; Gan, Thian Y

    2012-01-01

    Naphthenic acids, NAs (classical formula C(n)H(2n+z)O(2), where n is the carbon numbers, z represents zero or negative even integers), found in oil sands process waters (OSPWs), are toxic to aquatic environments depending upon several factors such as pH, salinity, molecular size and chemical structure of NAs. Among various available methods, biodegradation seems to be generally the most cost-effective method for decreasing concentrations of NAs (n ≤ 21) and reducing their associated toxicity in OSPW, however the mechanism by which the biodegradation of NAs occurs are poorly understood. Ozonation is superior over biodegradation in decreasing higher molecular weight alkyl branched NAs (preferentially, n ≥ 22, -6 ≥ z ≥ -12) as well as enabling accelerated biodegradation and reducing toxicity. Photolysis (UV at 254 nm) is effective in cleaving higher molecular weight NAs into smaller fragments that will be easier for microorganisms to degrade, whereas photocatalysis can metabolize selective NAs (0 ≥ z ≥ -6) efficiently and minimize their associated toxicity. Phytoremediation is applicable for metabolizing specific NAs (O(2), O(3), O(4), and O(5) species) and minimizing their associated toxicities. Petroleum coke (PC) adsorption is effective in reducing the more structurally complex NAs (preferentially 12 ≥ n ≥ 18 and z = -10, -12) and their toxicity in OSPWs, depending upon the PC content, pH and temperature. Several factors have influence on the degradation of NAs in OSPWs and aquatic environments, which include molecular mass and chemical structure of NAs, sediment structure, temperature, pH, dissolved oxygen, nutrients, and bacteria types. PMID:22217078

  7. Excretion pathways and ruminal disappearance of glyphosate and its degradation product aminomethylphosphonic acid in dairy cows.

    von Soosten, D; Meyer, U; Hüther, L; Dänicke, S; Lahrssen-Wiederholt, M; Schafft, H; Spolders, M; Breves, G

    2016-07-01

    From 6 balance experiments with total collection of feces and urine, samples were obtained to investigate the excretion pathways of glyphosate (GLY) in lactating dairy cows. Each experiment lasted for 26d. The first 21d served for adaptation to the diet, and during the remaining 5d collection of total feces and urine was conducted. Dry matter intake and milk yield were recorded daily and milk and feed samples were taken during the sampling periods. In 2 of the 6 experiments, at the sampling period for feces and urine, duodenal contents were collected for 5d. Cows were equipped with cannulas at the dorsal sac of the rumen and the proximal duodenum. Duodenal contents were collected every 2h over 5 consecutive days. The daily duodenal dry matter flow was measured by using chromium oxide as a volume marker. All samples (feed, feces, urine, milk and duodenal contents were analyzed for GLY and aminomethylphosphonic acid (AMPA). Overall, across the 6 experiments (n=32) the range of GLY intake was 0.08 to 6.67mg/d. The main proportion (61±11%; ±SD) of consumed GLY was excreted with feces; whereas excretion by urine was 8±3% of GLY intake. Elimination via milk was negligible. The GLY concentrations above the limit of quantification were not detected in any of the milk samples. A potential ruminal degradation of GLY to AMPA was derived from daily duodenal GLY flow. The apparent ruminal disappearance of GLY intake was 36 and 6%. In conclusion, the results of the present study indicate that the gastrointestinal absorption of GLY is of minor importance and fecal excretion represents the major excretion pathway. A degradation of GLY to AMPA by rumen microbes or a possible retention in the body has to be taken into account. PMID:27108173

  8. Chromatin-associated degradation is defined by UBXN-3/FAF1 to safeguard DNA replication fork progression.

    Franz, André; Pirson, Paul A; Pilger, Domenic; Halder, Swagata; Achuthankutty, Divya; Kashkar, Hamid; Ramadan, Kristijan; Hoppe, Thorsten

    2016-01-01

    The coordinated activity of DNA replication factors is a highly dynamic process that involves ubiquitin-dependent regulation. In this context, the ubiquitin-directed ATPase CDC-48/p97 recently emerged as a key regulator of chromatin-associated degradation in several of the DNA metabolic pathways that assure genome integrity. However, the spatiotemporal control of distinct CDC-48/p97 substrates in the chromatin environment remained unclear. Here, we report that progression of the DNA replication fork is coordinated by UBXN-3/FAF1. UBXN-3/FAF1 binds to the licensing factor CDT-1 and additional ubiquitylated proteins, thus promoting CDC-48/p97-dependent turnover and disassembly of DNA replication factor complexes. Consequently, inactivation of UBXN-3/FAF1 stabilizes CDT-1 and CDC-45/GINS on chromatin, causing severe defects in replication fork dynamics accompanied by pronounced replication stress and eventually resulting in genome instability. Our work identifies a critical substrate selection module of CDC-48/p97 required for chromatin-associated protein degradation in both Caenorhabditis elegans and humans, which is relevant to oncogenesis and aging. PMID:26842564

  9. Studies on the in vitro and in vivo degradation behavior of amino acid derivative-based organogels.

    Li, Zhen; Cao, Jinxu; Hu, Beibei; Li, Heran; Liu, Hongzhuo; Han, Fei; Liu, Zhenyun; Tong, Chao; Li, Sanming

    2016-11-01

    The in vitro degradation behavior of organogel with different gelators based on amino acid was investigated in detail. Two methods were applied in this research: weighting method and high-performance liquid chromatography with evaporative light scattering detection (HPLC-ELSD) method, which was established for the first time. Their degradation behaviors in vivo were investigated by varying the kind and concentration of gelators via subcutaneous implantation. The results showed that the stronger the gelation ability or the higher the gelator concentration, the slower the degradation rate of organogel. Moreover, the organogel prepared by oils with longer alkyl length degraded slower than that of the shorter ones, which also decreased in thermal stability and mechanical strength. The investigation on degradation process showed that the degradation rate was mainly controlled by the collapse of network structure formed by gelators. In conclusion, organogel had a tunable degradation rate through altering the gelator type, oil type and the gelator concentration. It remains a promising candidate for subcutaneous in-situ implant as drug delivery vehicle. PMID:27018332

  10. Progress in Acetic Acid Industry%醋酸工业现状及发展

    李好管; 闫慧芳

    2001-01-01

    醋酸是用途最广泛的有机酸之一。分析了醋酸的生产和消费趋势;综述了醋酸工艺的进展;介绍了具有工业化前景或学术价值的醋酸合成新工艺的研究开发概况。对我国醋酸工业发展提出了建议。%Acetic acid is one of the organic acids which have many uses.This paper analyzed the production and consumption of acetic acid,summarized the progress of acetic acid technology,introduced the research and development of acetic acid new process.Some suggestions on China's acetic acid industry were also put forward.

  11. The Analysis of Surrounding Structure Effect on the Core Degradation Progress with COMPASS Code

    Bae, Jun Ho; Son, Dong Gun; Kim, Jong Tae; Park, Rae Jun; Kim, Dong Ha [KAERI, Daejeon (Korea, Republic of)

    2015-05-15

    In line with the importance of severe accident analysis after Fukushima accident, the development of integrated severe accident code has been launched by the collaboration of three institutes in Korea. KAERI is responsible to develop modules related to the in-vessel phenomena, while other institutes are to the containment and severe accident mitigation facility, respectively. In the first phase, the individual severe accident module has been developed and the construction of integrated analysis code is planned to perform in the second phase. The basic strategy is to extend the design basis analysis codes of SPACE and CAP, which are being validated in Korea for the severe accident analysis. In the first phase, KAERI has targeted to develop the framework of severe accident code, COMPASS (COre Meltdown Progression Accident Simulation Software), covering the severe accident progression in a vessel from a core heat-up to a vessel failure as a stand-alone fashion. In order to analyze the effect of surrounding structure, the melt progression has been compared between the central zone and the most outer zone under the condition of constant radial power peaking factor. Figure 2 and 3 shows the fuel element temperature and the clad mass at the central zone, respectively. Due to the axial power peaking factor, the axial node No.3 has the highest temperature, while the top and bottom nodes have the lowest temperature. When the clad temperature reaches to the Zr melting temperature (2129.15K), the Zr starts to melt. The axial node No.2 reaches to the fuel melting temperature about 5000 sec and the molten fuel relocates to the node No.1, which results to the blockage of flow area in node No.1. The blocked flow area becomes to open about 6100 sec due to the molten ZrO{sub 2} mass relocation to core support plate. Figure 4 and 5 shows the fuel element temperature and the clad mass at the most outer zone, respectively. It is shown that the fuel temperature increase more slowly

  12. Progress report on nitric-phosphoric acid oxidation

    The purpose of this program has been to demonstrate a nitric-phosphoric acid destruction technology which can treat a heterogeneous waste stream. This technology is being developed to convert hazardous liquid and solid organics to inorganic gases and salts while simultaneously performing a surface decontamination of the noncombustible items. Pu-238 waste is an issue because it must be shipped to WIPP. However, the presence of organics and Pu-238 waste is an issue because it must be shipped to WIPP. However, the presence of organics and Pu-238 exceeds packaging requirements because of concerns of hydrogen generation. If the TRU can be separated from the organics, the allowable heat load of a container increases a factor of 25. More importantly, since the current shipping package is limited by volume and not heat loading, destroying the organic compounds and decontaminating noncombustible can potentially create a three-order magnitude decrease in the number of shipments that must be made to WIPP. The process envisioned will be configured to handle 1 million pounds (as of 12/91) of a wide range of solid TRU-contaminated waste of which 600,000 pounds is combustible. The process will oxidize the combustibles (a mixture of 14% cellulose, 3% rubber, 64% plastics, 9% absorbed oil, 4% resins and sludges, and 6% miscellaneous organics) without requiring separation from the 400,000 pounds of noncombustibles. The system is being developed to operate below 200 C at moderate pressures (0--15 psig). This report primarily discusses results obtained over the past 3 1/2 months and their impact on the feasibility of a pilot-scale system

  13. Abiotic Degradation Rates for Carbon Tetrachloride and Chloroform: Progress in FY2009

    Amonette, James E.; Jeffers, Peter M.; Qafoku, Odeta; Russell, Colleen K.; Wietsma, Thomas W.; Truex, Michael J.

    2010-03-31

    This report documents the progress made through FY 2009 on a project initiated in FY 2006 to help address uncertainties related to the rates of hydrolysis in groundwater for carbon tetrachloride (CT) and chloroform (CF). The study seeks also to explore the possible effects of contact with minerals and sediment (i.e., heterogeneous hydrolysis) on these rates. In previous years the work was funded as two separate projects by various sponsors, all of whom received their funding from the U.S. Department of Energy (DOE). In FY2009, the projects were combined and funded by CH2MHill Plateau Remediation Corporation (CHPRC). Work in FY2009 was performed by staff at the Pacific Northwest National Laboratory (PNNL). Staff from the State University of New York at Cortland (SUNY–Cortland) contributed in previous years.

  14. Obesity and Cancer Progression: Is There a Role of Fatty Acid Metabolism?

    Seher Balaban

    2015-01-01

    Full Text Available Currently, there is renewed interest in elucidating the metabolic characteristics of cancer and how these characteristics may be exploited as therapeutic targets. Much attention has centered on glucose, glutamine and de novo lipogenesis, yet the metabolism of fatty acids that arise from extracellular, as well as intracellular, stores as triacylglycerol has received much less attention. This review focuses on the key pathways of fatty acid metabolism, including uptake, esterification, lipolysis, and mitochondrial oxidation, and how the regulators of these pathways are altered in cancer. Additionally, we discuss the potential link that fatty acid metabolism may serve between obesity and changes in cancer progression.

  15. In vitro cytotoxic and genotoxic effects of diphenylarsinic acid, a degradation product of chemical warfare agents

    Diphenylarsinic acid [DPAs(V)], a degradation product of diphenylcyanoarsine or diphenylchloroarsine, both of which were developed as chemical warfare agents, was investigated in terms of its capacity to induce cytotoxic effects, numerical and structural changes of chromosomes, and abnormalities of centrosome integrity and spindle organizations in conjunction with the effects of glutathione (GSH) depletion. DPAs(V) had toxic effects on cultured human hepatocarcinoma HepG2 cells at concentrations more than 0.5 mM. Depletion of GSH reduced the toxic effects of DPAs(V) as well as dimethylarsinic acid [DMAs(V)] toxicity, while toxicity by arsenite [iAs(III)] was enhanced. Exogenously added sulfhydryl (SH) compounds, such as dimercapropropane sulfonate (DMPS), GSH, and dithiothreitol (DTT), enhanced the toxic effects of DPAs(V) while they suppressed iAs(III) toxicity. DPAs(V) caused an increase in the mitotic index, and also structural and numerical changes in chromosomes in V79 Chinese hamster cells. Abnormality of centrosome integrity in mitotic V79 cells and multipolar spindles was also induced by DPAs(V) in a time- and concentration-dependent manner. These results suggested that highly toxic chemicals were generated by the interaction of DPAs(V) with SH compounds. Moreover, enhancements of toxicity by a combination of DPAs(V) and SH compounds suggested a risk in the use of SH compounds as a remedy for intoxication by diphenylarsenic compounds. Investigations on the effects of SH compounds on animals intoxicated with DPAs(V) are warranted

  16. A STUDY ON THE DEGRADATION MECHANISM OF PHOTOCROSSLINKING PRODUCTS FORMED BY CYCLIZED POLYISOPRENE-DIAZIDE SYSTEM UNDER THE INFLUENCE OF ALKYL BENZENE SULFONIC ACIDS

    HUANG Junlian; SUN Meng

    1989-01-01

    The degradation mechanism of photocrosslinking products formed by cyclized polyisoprene-diazide system under the influence of the different alkyl benzene sulfonic acids was studied. The effects ofalkyl chain length and the concentration of alkyl benzene sulfonic acids on the rate of degradation reaction were discussed. It was found that in the initial stage of degradation, the cyclicity ratio and the average fused ring number did not change considerably, but the percentage of uncyclized parts content varied significantly. The suitable mechanism was supposed.

  17. Perfluorooctanoic acid degradation in the presence of Fe(III) under natural sunlight

    Highlights: • PFOA was photo-chemically decomposed in the presence of Fe(III) and natural sunlight. • An alternative reaction pathway involves hydroxyl radical as confirmed by EPR. • Common oxidant-persulfate increased PFOA defluorination extent. -- Abstract: Due to the high bond dissociation energy (BDE) of C-F bonds (116 kcal/mol), perfluorooctanoic acid (PFOA) is a highly recalcitrant pollutant. Herein, we demonstrate a novel method to decompose PFOA in the presence of sunlight and ferric iron (Fe(III)). Under such conditions, 97.8 ± 1.7% of 50 μM PFOA decomposed within 28 days into shorter-chain intermediates and fluoride (F−), with an overall defluorination extent of 12.7 ± 0.5%. No PFOA was removed under visible light, indicating that UV radiation is required for PFOA decomposition. Spectroscopic analysis indicates that the decomposition reaction is likely initiated by electron-transfer from PFOA to Fe(III), forming Fe(II) and an unstable organic carboxyl radical. An alternative mechanism for the formation of this organic radical involves hydroxyl radicals, detected by electron paramagnetic resonance (EPR). The observation that PFOA can be degraded by Fe(III) under solar irradiation provides mechanistic insight into a possibly overlooked natural attenuation process. Because Fe(III) is abundant in natural waters and sunlight is essentially free, this work represents a potentially important step toward the development of simple and inexpensive remediation strategies for PFOA-contaminated water

  18. Perfluorooctanoic acid degradation in the presence of Fe(III) under natural sunlight

    Liu, Dandan [Beijing Key Laboratory of Water Resource and Environmental Engineering, China University of Geosciences, Beijing 100083 (China); Xiu, Zongming [Department of Civil and Environmental Engineering, Rice University, Houston, TX 77005 (United States); Liu, Fei [Beijing Key Laboratory of Water Resource and Environmental Engineering, China University of Geosciences, Beijing 100083 (China); Wu, Gang [Division of Hematology, Department of Internal Medicine, University of Texas-Medical School at Houston, Houston, TX 77030 (United States); Adamson, Dave; Newell, Charles [GSI Environmental Inc., Houston, TX 77098 (United States); Vikesland, Peter [Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061 (United States); Tsai, Ah-Lim [Division of Hematology, Department of Internal Medicine, University of Texas-Medical School at Houston, Houston, TX 77030 (United States); Alvarez, Pedro J., E-mail: alvarez@rice.edu [Department of Civil and Environmental Engineering, Rice University, Houston, TX 77005 (United States)

    2013-11-15

    Highlights: • PFOA was photo-chemically decomposed in the presence of Fe(III) and natural sunlight. • An alternative reaction pathway involves hydroxyl radical as confirmed by EPR. • Common oxidant-persulfate increased PFOA defluorination extent. -- Abstract: Due to the high bond dissociation energy (BDE) of C-F bonds (116 kcal/mol), perfluorooctanoic acid (PFOA) is a highly recalcitrant pollutant. Herein, we demonstrate a novel method to decompose PFOA in the presence of sunlight and ferric iron (Fe(III)). Under such conditions, 97.8 ± 1.7% of 50 μM PFOA decomposed within 28 days into shorter-chain intermediates and fluoride (F{sup −}), with an overall defluorination extent of 12.7 ± 0.5%. No PFOA was removed under visible light, indicating that UV radiation is required for PFOA decomposition. Spectroscopic analysis indicates that the decomposition reaction is likely initiated by electron-transfer from PFOA to Fe(III), forming Fe(II) and an unstable organic carboxyl radical. An alternative mechanism for the formation of this organic radical involves hydroxyl radicals, detected by electron paramagnetic resonance (EPR). The observation that PFOA can be degraded by Fe(III) under solar irradiation provides mechanistic insight into a possibly overlooked natural attenuation process. Because Fe(III) is abundant in natural waters and sunlight is essentially free, this work represents a potentially important step toward the development of simple and inexpensive remediation strategies for PFOA-contaminated water.

  19. Effect of humic acids on electricity generation integrated with xylose degradation in microbial fuel cells

    Huang, Liping; Angelidaki, Irini

    2008-01-01

    Pentose and humic acids (HA) are the main components of hydrolysates, the liquid fraction produced during thermohydrolysis of lignocellulosic material. Electricity generation integrated with xylose (typical pentose) degradation as well as the effect of HA on electricity production in microbial fuel...... cells (MFCs) was examined. Without HA addition the maximum power density increased from 39.5 mW/m2 to 83 mW/m2 when initial xylose concentrations increased from 1.5 to 30 mM, while coulombic efficiency ranged from 13.5% to 52.4% for xylose concentrations of 15 and 0.5 mM, respectively. Compared to...... controls where HAs were not added, addition of commercial HA resulted in increase of power density and coulombic efficiency, which ranged from 7.5% to 67.4% and 24% to 92.6%, respectively. Digested manure wastewater (DMW) was tested as potential mediator for power generation due to its content of natural...

  20. Comparative studies of phenol and salicylic acid photocatalytic degradation: influence of adsorbed oxygen

    Porous TiO2 and mixed mesoporous (SiO2:TiO2 95:5 in molar ratio) have been synthesized by a sol-gel method followed by a supercritical i-PrOH treatment (300 deg. C, 80 bar) and using a template molecule. They have been characterized by X-ray diffraction, scanning electron microscopy and specific surface area measurements. A photocatalytic degradation of phenol and salicylic acid investigated as a function of calcination temperature allows to obtain a best sample at 450 deg. C (SD450 TiO2). The surface hydroxyl amount of the lab-made photocatalyst and that of the commercial powders (Degussa P25, Sachtleben Hombikat UV100 and Acros TiO2) have been compared. This factor is found to strongly modify the O2 adsorption. The commercial Hombikat and Acros TiO2 have been found to be less active than SD450 and P25 TiO2 under identical condition confirming in this way the dominant role of surface OH groups. In addition, for Acros TiO2 the phenol photodegradation shows a formation of numerous oxidative intermediate products. Their identification permits to indicate that the photolysis significantly occurs because of a low concentration of OH· radicals whereas for SD450 or Degussa P25 TiO2, these behaviours appear negligible

  1. Occurrence and fate of the herbicide glyphosate and its degradate aminomethylphosphonic acid in the atmosphere

    Chang, Feng-Chih; Simcik, M.F.; Capel, P.D.

    2011-01-01

    This is the first report on the ambient levels of glyphosate, the most widely used herbicide in the United States, and its major degradation product, aminomethylphosphonic acid (AMPA), in air and rain. Concurrent, weekly integrated air particle and rain samples were collected during two growing seasons in agricultural areas in Mississippi and Iowa. Rain was also collected in Indiana in a preliminary phase of the study. The frequency of glyphosate detection ranged from 60 to 100% in both air and rain. The concentrations of glyphosate ranged from 3 and from glyphosate in air were similar or greater to those of the other high-use herbicides observed in the Mississippi River basin, whereas its concentration in rain was greater than the other herbicides. It is not known what percentage of the applied glyphosate is introduced into the air, but it was estimated that up to 0.7% of application is removed from the air in rainfall. Glyphosate is efficiently removed from the air; it is estimated that an average of 97% of the glyphosate in the air is removed by a weekly rainfall ≥30 mm.

  2. Target-specific intracellular delivery of siRNA using degradable hyaluronic acid nanogels.

    Lee, Hyukjin; Mok, Hyejung; Lee, Soohyeon; Oh, Yu-Kyoung; Park, Tae Gwan

    2007-06-01

    Novel hyaluronic acid (HA) nanogels physically encapsulating small interfering RNA (siRNA) were fabricated by an inverse water-in-oil emulsion method. Thiol-conjugated HA dissolved in aqueous emulsion droplets was ultrasonically crosslinked via the formation of disulfide linkages to produce HA nanogels with a size distribution from 200 to 500 nm. Green fluorescence protein (GFP) siRNA was physically entrapped within the HA nanogels during the emulsion/crosslinking process. The HA/siRNA nanogels were readily taken up by HA receptor positive cells (HCT-116 cells) having HA-specific CD44 receptors on the surface. Release rates of siRNA from the HA nanogels could be modulated by changing the concentration of glutathione (GSH) in the buffer solution, indicating that the degradation/erosion of disulfide crosslinked HA nanogels, triggered by an intracellular reductive agent, controlled the release pattern of siRNA. When HA nanogels containing GFP siRNA were co-transfected with GFP plasmid/Lipofectamine to HCT-116 cells, a significant extent of GFP gene silencing was observed in both serum and non-serum conditions. The gene silencing effect was reduced in the presence of free HA in the transfection medium, revealing that HA nanogels were selectively taken up by HCT-116 cells via receptor mediated endocytosis. PMID:17408798

  3. Malic acid degradation by indigenous and commercial Saccharomyces cerevisiae wine strains

    Pereira, Leonor; Schuller, Dorit; Queirós, Odília; Ferreira, Pedro Moradas; Casal, Margarida

    2006-01-01

    Malic acid contributes to the acidic taste of wine and is, together with tartaric acid, the most abundant organic acid in wine. Contaminating lactic acid bacteria cause wine spoilage after bottling and may use malic acid as a substrate. It is therefore essential to remove excess malic acid from wines to ensure their physical, biochemical and microbial stability. The aim of this work was to gain insight in the differences regarding malic acid metabolism under fermentative conditions among ...

  4. Enantioselective degradation and unidirectional chiral inversion of 2-phenylbutyric acid, an intermediate from linear alkylbenzene, by Xanthobacter flavus PA1

    Liu, Yishan; Han, Ping [School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong (China); Li, Xiao-yan; Shih, Kaimin [Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong (China); Gu, Ji-Dong, E-mail: jdgu@hkucc.hku.hk [School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong (China); The Swire Institute of Marine Science, The University of Hong Kong, Shek O, Cape d' Aguilar, Hong Kong (China)

    2011-09-15

    Highlights: {yields} We isolated a Xanthobacter flavus strain PA1 utilizing the racemic 2-PBA and the single enantiomers as the sole source of carbon and energy. {yields} Both (R) and (S) forms of enantiomers can be degraded in a sequential manner in which the (S) disappeared before the (R) form. {yields} The biochemical degradation pathway involves an initial oxidation of the alkyl side chain before aromatic ring cleavage. - Abstract: Microbial degradation of the chiral 2-phenylbutyric acid (2-PBA), a metabolite of surfactant linear alkylbenzene sulfonates (LAS), was investigated using both racemic and enantiomer-pure compounds together with quantitative stereoselective analyses. A pure culture of bacteria, identified as Xanthobacter flavus strain PA1 isolated from the mangrove sediment of Hong Kong Mai Po Nature Reserve, was able to utilize the racemic 2-PBA as well as the single enantiomers as the sole source of carbon and energy. In the presence of the racemic compounds, X. flavus PA1 degraded both (R) and (S) forms of enantiomers to completion in a sequential manner in which the (S) enantiomer disappeared much faster than the (R) enantiomer. When the single pure enantiomer was supplied as the sole substrate, a unidirectional chiral inversion involving (S) enantiomer to (R) enantiomer was evident. No major difference was observed in the degradation intermediates with either of the individual enantiomers when used as the growth substrate. Two major degradation intermediates were detected and identified as 3-hydroxy-2-phenylbutanoic acid and 4-methyl-3-phenyloxetan-2-one, using a combination of liquid chromatography-mass spectrometry (LC-MS), and {sup 1}H and {sup 13}C nuclear magnetic resonance (NMR) spectroscopy. The biochemical degradation pathway follows an initial oxidation of the alkyl side chain before aromatic ring cleavage. This study reveals new evidence for enantiomeric inversion catalyzed by pure culture of environmental bacteria and emphasizes the

  5. Structural Characterization of the Degradation Products of a Minor Natural Sweet Diterpene Glycoside Rebaudioside M under Acidic Conditions

    Indra Prakash; Venkata Sai Prakash Chaturvedula; Avetik Markosyan

    2014-01-01

    Degradation of rebaudioside M, a minor sweet component of Stevia rebaudiana Bertoni, under conditions that simulated extreme pH and temperature conditions has been studied. Thus, rebaudioside M was treated with 0.1 M phosphoric acid solution (pH 2.0) and 80 °C temperature for 24 h. Experimental results indicated that rebaudioside M under low pH and higher temperature yielded three minor degradation compounds, whose structural characterization was performed on the basis of 1D (1H-, 13C-) &...

  6. Structural Characterization of the Degradation Products of a Minor Natural Sweet Diterpene Glycoside Rebaudioside M under Acidic Conditions

    Prakash, Indra; Chaturvedula, Venkata Sai Prakash; Markosyan, Avetik

    2014-01-01

    Degradation of rebaudioside M, a minor sweet component of Stevia rebaudiana Bertoni, under conditions that simulated extreme pH and temperature conditions has been studied. Thus, rebaudioside M was treated with 0.1 M phosphoric acid solution (pH 2.0) and 80 °C temperature for 24 h. Experimental results indicated that rebaudioside M under low pH and higher temperature yielded three minor degradation compounds, whose structural characterization was performed on the basis of 1D (1H-, 13C-) & 2D ...

  7. Degradation mechanisms of poly (lactic-co-glycolic acid) films in vitro under static and dynamic environment

    HUANG Ying-ying; QI Min; ZHANG Meng; LIU Hong-ze; YANG Da-zhi

    2006-01-01

    To understand their degradation mechanisms,PLGA (50:50) polymer films were prepared and eroded in the static and dynamic medium system. The degradation behavior was characterized through weight-average molecular weight change,mass loss,water uptake,etc. The results show that in dynamic system,significant mass loss begins until 10 d while mass loss does not begin until 30 d later,while weight-average molecular weight decreases observably at the beginning,and the appeasable mass loss happens in 20 d in static system,which suggests that the dynamic degradation rate is slower even than degradation in static medium. A mechanism was proposed that specimens in static medium take up water homogeneously and cause the polymer chains to degrade all over the specimen cross sections,which creates free carboxylic acid groups which lead to a decrease of pH value inside the swollen polymer and accelerate degradation of the polymer. While pH value inside polymer keeps constant in dynamic medium because of flowing of simulated medium,which make the hydrolytic cleavage of ester bonds inside specimen delayed.

  8. Acidic nanoparticles are trafficked to lysosomes and restore an acidic lysosomal pH and degradative function to compromised ARPE-19 cells.

    Gabriel C Baltazar

    Full Text Available Lysosomal enzymes function optimally in acidic environments, and elevation of lysosomal pH can impede their ability to degrade material delivered to lysosomes through autophagy or phagocytosis. We hypothesize that abnormal lysosomal pH is a key aspect in diseases of accumulation and that restoring lysosomal pH will improve cell function. The propensity of nanoparticles to end up in the lysosome makes them an ideal method of delivering drugs to lysosomes. This study asked whether acidic nanoparticles could traffic to lysosomes, lower lysosomal pH and enhance lysosomal degradation by the cultured human retinal pigmented epithelial cell line ARPE-19. Acidic nanoparticles composed of poly (DL-lactide-co-glycolide (PLGA 502 H, PLGA 503 H and poly (DL-lactide (PLA colocalized to lysosomes of ARPE-19 cells within 60 min. PLGA 503 H and PLA lowered lysosomal pH in cells compromised by the alkalinizing agent chloroquine when measured 1 hr. after treatment, with acidification still observed 12 days later. PLA enhanced binding of Bodipy-pepstatin-A to the active site of cathepsin D in compromised cells. PLA also reduced the cellular levels of opsin and the lipofuscin-like autofluorescence associated with photoreceptor outer segments. These observations suggest the acidification produced by the nanoparticles was functionally effective. In summary, acid nanoparticles lead to a rapid and sustained lowering of lysosomal pH and improved degradative activity.

  9. Characterization of the effect of sample quality on high density oligonucleotide microarray data using progressively degraded rat liver RNA

    Rosenzweig Barry A

    2007-09-01

    Full Text Available Abstract Background The interpretability of microarray data can be affected by sample quality. To systematically explore how RNA quality affects microarray assay performance, a set of rat liver RNA samples with a progressive change in RNA integrity was generated by thawing frozen tissue or by ex vivo incubation of fresh tissue over a time course. Results Incubation of tissue at 37°C for several hours had little effect on RNA integrity, but did induce changes in the transcript levels of stress response genes and immune cell markers. In contrast, thawing of tissue led to a rapid loss of RNA integrity. Probe sets identified as most sensitive to RNA degradation tended to be located more than 1000 nucleotides upstream of their transcription termini, similar to the positioning of control probe sets used to assess sample quality on Affymetrix GeneChip® arrays. Samples with RNA integrity numbers less than or equal to 7 showed a significant increase in false positives relative to undegraded liver RNA and a reduction in the detection of true positives among probe sets most sensitive to sample integrity for in silico modeled changes of 1.5-, 2-, and 4-fold. Conclusion Although moderate levels of RNA degradation are tolerated by microarrays with 3'-biased probe selection designs, in this study we identify a threshold beyond which decreased specificity and sensitivity can be observed that closely correlates with average target length. These results highlight the value of annotating microarray data with metrics that capture important aspects of sample quality.

  10. Performance Degradation Tests of Phosphoric Acid Doped Polybenzimidazole Membrane Based High Temperature Polymer Electrolyte Membrane Fuel Cells

    Zhou, Fan; Araya, Samuel Simon; Grigoras, Ionela; Andreasen, Søren Juhl; Kær, Søren Knudsen

    2015-01-01

    Degradation tests of two phosphoric acid (PA) doped PBI membrane based HT-PEM fuel cells were reported in this paper to investigate the effects of start/stop and the presence of methanol in the fuel to the performance degradation of the HT-PEM fuel cell. Continuous tests with pure dry H2 and...... performance during the H2 continuous tests, because of a decrease in the reaction kinetic resistance mainly in the cathode due to the redistribution of PA between the membrane and electrodes. The performance of both single cells decreased in the following tests, with highest performance decay rate in the...... corrosion of carbon support in the catalyst layer and degradation of the PBI membrane. During the continuous test with methanol containing H2 as the fuel the reaction kinetic resistance and mass transfer resistance of both single cells increased, which may be caused by the adsorption of methanol...