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Sample records for acid degradation rate

  1. Degradation rates of glycerol polyesters at acidic and basic conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Polyesters prepared from glycerol with mixtures of adipic and citric acids were evaluated in the laboratory to estimate degradation rates over a range of pH conditions. These renewable polymers provide a market for glycerol that is generated during biodiesel production. The polyesters were prepared...

  2. Rate Motifs Tune Auxin/Indole-3-Acetic Acid Degradation Dynamics1[OPEN

    PubMed Central

    Moss, Britney L.; Mao, Haibin; Guseman, Jessica M.; Hinds, Thomas R.; Hellmuth, Antje; Kovenock, Marlies; Noorassa, Anisa; Lanctot, Amy; Villalobos, Luz Irina A. Calderón; Zheng, Ning; Nemhauser, Jennifer L.

    2015-01-01

    Ubiquitin-mediated protein degradation is a common feature in diverse plant cell signaling pathways; however, the factors that control the dynamics of regulated protein turnover are largely unknown. One of the best-characterized families of E3 ubiquitin ligases facilitates ubiquitination of auxin (aux)/indole-3-acetic acid (IAA) repressor proteins in the presence of auxin. Rates of auxin-induced degradation vary widely within the Aux/IAA family, and sequences outside of the characterized degron (the minimum region required for auxin-induced degradation) can accelerate or decelerate degradation. We have used synthetic auxin degradation assays in yeast (Saccharomyces cerevisiae) and in plants to characterize motifs flanking the degron that contribute to tuning the dynamics of Aux/IAA degradation. The presence of these rate motifs is conserved in phylogenetically distant members of the Arabidopsis (Arabidopsis thaliana) Aux/IAA family, as well as in their putative Brassica rapa orthologs. We found that rate motifs can act by enhancing interaction between repressors and the E3, but that this is not the only mechanism of action. Phenotypes of transgenic plants expressing a deletion in a rate motif in IAA28 resembled plants expressing degron mutations, underscoring the functional relevance of Aux/IAA degradation dynamics in regulating auxin responses. PMID:26149575

  3. Rate Motifs Tune Auxin/Indole-3-Acetic Acid Degradation Dynamics.

    PubMed

    Moss, Britney L; Mao, Haibin; Guseman, Jessica M; Hinds, Thomas R; Hellmuth, Antje; Kovenock, Marlies; Noorassa, Anisa; Lanctot, Amy; Villalobos, Luz Irina A Calderón; Zheng, Ning; Nemhauser, Jennifer L

    2015-09-01

    Ubiquitin-mediated protein degradation is a common feature in diverse plant cell signaling pathways; however, the factors that control the dynamics of regulated protein turnover are largely unknown. One of the best-characterized families of E3 ubiquitin ligases facilitates ubiquitination of auxin (aux)/indole-3-acetic acid (IAA) repressor proteins in the presence of auxin. Rates of auxin-induced degradation vary widely within the Aux/IAA family, and sequences outside of the characterized degron (the minimum region required for auxin-induced degradation) can accelerate or decelerate degradation. We have used synthetic auxin degradation assays in yeast (Saccharomyces cerevisiae) and in plants to characterize motifs flanking the degron that contribute to tuning the dynamics of Aux/IAA degradation. The presence of these rate motifs is conserved in phylogenetically distant members of the Arabidopsis (Arabidopsis thaliana) Aux/IAA family, as well as in their putative Brassica rapa orthologs. We found that rate motifs can act by enhancing interaction between repressors and the E3, but that this is not the only mechanism of action. Phenotypes of transgenic plants expressing a deletion in a rate motif in IAA28 resembled plants expressing degron mutations, underscoring the functional relevance of Aux/IAA degradation dynamics in regulating auxin responses. PMID:26149575

  4. Decomposition of phenylarsonic acid by AOP processes: degradation rate constants and by-products.

    PubMed

    Jaworek, K; Czaplicka, M; Bratek, Ł

    2014-10-01

    The paper presents results of the studies photodegradation, photooxidation, and oxidation of phenylarsonic acid (PAA) in aquatic solution. The water solutions, which consist of 2.7 g dm(-3) phenylarsonic acid, were subjected to advance oxidation process (AOP) in UV, UV/H2O2, UV/O3, H2O2, and O3 systems under two pH conditions. Kinetic rate constants and half-life of phenylarsonic acid decomposition reaction are presented. The results from the study indicate that at pH 2 and 7, PAA degradation processes takes place in accordance with the pseudo first order kinetic reaction. The highest rate constants (10.45 × 10(-3) and 20.12 × 10(-3)) and degradation efficiencies at pH 2 and 7 were obtained at UV/O3 processes. In solution, after processes, benzene, phenol, acetophenone, o-hydroxybiphenyl, p-hydroxybiphenyl, benzoic acid, benzaldehyde, and biphenyl were identified. PMID:24824504

  5. Microbial degradation rates of small peptides and amino acids in the oxygen minimum zone of Chilean coastal waters

    NASA Astrophysics Data System (ADS)

    Pantoja, Silvio; Rossel, Pamela; Castro, Rodrigo; Cuevas, L. Antonio; Daneri, Giovanni; Córdova, Candy

    2009-07-01

    We found similar microbial degradation rates of labile dissolved organic matter in oxic and suboxic waters off northern Chile. Rates of peptide hydrolysis and amino acid uptake in unconcentrated water samples were not low in the water column where oxygen concentration was depleted. Hydrolysis rates ranged from 65 to 160 nmol peptide L -1 h -1 in the top 20 m, 8-28 nmol peptide L -1 h -1 between 100 and 300 m (O 2-depleted zone), and 14-19 nmol peptide L -1 h -1 between 600 and 800 m. Dissolved free amino acid uptake rates were 9-26, 3-17, and 6 nmol L -1 h -1 at similar depth intervals. Since these findings are consistent with a model of comparable potential activity of microbes in degrading labile substrates of planktonic origin, we suggest, as do other authors, that differences in decomposition rates with high and low oxygen concentrations may be a matter of substrate lability. The comparison between hydrolysis and uptake rates indicates that microbial peptide hydrolysis occurs at similar or faster rates than amino acid uptake in the water column, and that the hydrolysis of peptides is not a rate-limiting step for the complete remineralization of labile macromolecules. Low O 2 waters process about 10 tons of peptide carbon per h, double the amount processed in surface-oxygenated water. In the oxygen minimum zone, we suggest that the C balance may be affected by the low lability of the dissolved organic matter when this is upwelled to the surface. An important fraction of dissolved organic matter is processed in the oxygen minimum layer, a prominent feature of the coastal ocean in the highly productive Humboldt Current System.

  6. Assessment of urea degradation rate in model wine solutions by acid urease from Lactobacillus fermentum.

    PubMed

    Fidaleo, Marcello; Esti, Marco; Moresi, Mauro

    2006-08-23

    The specific activity (piA) of a whole cell acid urease preparation was assessed in model wine solutions at different levels of malic (M) and lactic acids, metabisulfite, ethanol, and pH by performing a central composite design. M and then pH were found to be the most controlling variables, their effects being practically coincident but of opposite sign. For urea concentrations up to approximately 1 mol m(-3) the ammonium formation rate was assumed of the pseudo-first-order with respect to urea, this being confirmed by two independent validation tests performed at 20 degrees C for as long as 24 h. In the case of real wines the effective pseudo-first-order kinetic rate constants were found to be smaller than those pertaining to the model solutions having the same wine composition and pH by a factor varying from 10 to 1000, this affecting significantly the specific urease treatment costs per liter of wine treated. PMID:16910712

  7. Rates and mechanisms of fatty acid degradation in oxic and anoxic coastal marine sediments of Long Island Sound, New York, USA

    NASA Astrophysics Data System (ADS)

    Sun, Ming-Yi; Wakeham, Stuart G.; Lee, Cindy

    1997-01-01

    The rates and pathways of labile organic matter degradation significantly affect the cycling of organic carbon and nutrients in coastal sediments. In this study, we measured degradation rate constants of saturated and unsaturated fatty acids by incubating radiolabeled 1- 14C-palmitic (16:0) and 1- 14C-oleic (18:1) acids and an unlabeled plankton mixture in oxic and anoxic sediments from Long Island Sound (LIS) under laboratory-controlled conditions. Rate constants for degradation of 16:0 and 18:1 fatty acids were higher in oxic sediments than in anoxic sediments. Degradation of the unsaturated 18:1 acid in anoxic sediments was two times faster than for 16:0, while there was little difference between the two fatty acids in oxic sediments. The incubation results clearly showed that fatty acids degrade through multiple pathways in both oxic and anoxic sediments. About 80-90% of the label was lost from the incubated sediments (presumably as 14CO 2 or other volatile products), and 5-10% was incorporated into the sediment matrix. Both degradation and incorporation into the sediment matrix were slightly greater under oxic conditions. A small part (5-10%) of the label was incorporated into what are presumed to be metabolic products. A higher percentage of this incorporation occurred under anoxic conditions, implying that anaerobic bacteria are less efficient at degrading the labeled fatty acid to volatile products such as CO 2. In the oxic sediments, more oleic than palmitic acid was converted into intermediate metabolites, indicating that the unsaturated fatty acid was degraded less efficiently. There was little difference in formation of metabolites between oleic and palmitic acids under anoxic conditions. The seasonal distributions of palmitic and oleic acids at two coastal LIS sites with distinctive oxygen content were modeled to yield degradation rate constants for these two fatty acids. The comparison between fatty acid degradation rate constants derived from

  8. Degradation of ascorbic acid in ethanolic solutions.

    PubMed

    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

  9. Acid rain degradation of nylon

    SciTech Connect

    Kyllo, K.E.

    1984-01-01

    Acid rain, precipitation with a pH less than 5.6, is known to damage lakes, vegetation and buildings. Degradation of outdoor textiles by acid rain is strongly suspected but not well documented. This study reports the effects of sunlight, aqueous acid, heat and humidity (acid rain conditions) on spun delustered nylon 6,6 fabric. Untreated nylon and nylon treated with sulfuric acid of pH 2.0, 3.0, and 4.4 were exposed to light in an Atlas Xenon-arc fadeometer at 63/sup 0/C and 65% R.H. for up to 640 AATCC Fading Units. The untreated and acid treated nylon fabrics were also exposed to similar temperature and humidity condition without light. Nylon degradation was determined by changes in breaking strength, elongation, molecular weight, color, amino end group concentration (NH/sub 2/) and /sup 13/C NMR spectra. Physical damage was assessed using SEM.

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

    PubMed

    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

  11. Measuring Degradation Rates Without Irradiance Data

    SciTech Connect

    Pulver, S.; Cormode, D.; Cronin, A.; Jordan, D.; Kurtz, S.; Smith, R.

    2011-02-01

    A method to report PV system degradation rates without using irradiance data is demonstrated. First, a set of relative degradation rates are determined by comparing daily AC final yields from a group of PV systems relative to the average final yield of all the PV systems. Then, the difference between relative and absolute degradation rates is found from a statistical analysis. This approach is verified by comparing to methods that utilize irradiance data. This approach is significant because PV systems are often deployed without irradiance sensors, so the analysis method described here may enable measurements of degradation using data that were previously thought to be unsuitable for degradation studies.

  12. Photovoltaic Degradation Rates -- An Analytical Review

    SciTech Connect

    Jordan, D. C.; Kurtz, S. R.

    2012-06-01

    As photovoltaic penetration of the power grid increases, accurate predictions of return on investment require accurate prediction of decreased power output over time. Degradation rates must be known in order to predict power delivery. This article reviews degradation rates of flat-plate terrestrial modules and systems reported in published literature from field testing throughout the last 40 years. Nearly 2000 degradation rates, measured on individual modules or entire systems, have been assembled from the literature, showing a median value of 0.5%/year. The review consists of three parts: a brief historical outline, an analytical summary of degradation rates, and a detailed bibliography partitioned by technology.

  13. Nanobiocatalytic Degradation of Acid Orange 7

    NASA Astrophysics Data System (ADS)

    Hastings, Jason

    The catalytic properties of various metal nanoparticles have led to their use in environmental remediation applications. However, these remediation strategies are limited by their ability to deliver catalytic nanoparticles and a suitable electron donor to large treatment zones. Clostridium pasteurianum BC1 cells, loaded with bio-Pd nanoparticles, were used to effectively catalyze the reductive degradation and removal of Acid Orange 7 (AO7), a model azo compound. Hydrogen produced fermentatively by the C. pasteurianum BC1 acted as the electron donor for the process. Pd-free bacterial cultures or control experiments conducted with heat-killed cells showed limited reduction of AO7. Experiments also showed that the in situ biological production of H2 by C. pasteurianum BC1 was essential for the degradation of AO7, which suggests a novel process where the in situ microbial production of hydrogen is directly coupled to the catalytic bio-Pd mediated reduction of AO7. The differences in initial degradation rate for experiments conducted using catalyst concentrations of 1ppm Pd and 5ppm Pd and an azo dye concentration of 100ppm AO7 was 0.39 /hr and 1.94 /hr respectively, demonstrating the importance of higher concentrations of active Pd(0). The degradation of AO7 was quick as demonstrated by complete reductive degradation of 50ppm AO7 in 2 hours in experiments conducted using a catalyst concentration of 5ppm Pd. Dye degradation products were analyzed via Gas Chromatograph-Mass Spectrometer (GCMS), High Performance Liquid Chromatography (HPLC), UltraViolet-Visible spectrophotometer (UV-Vis) and Matrix-Assisted Laser Desorption/Ionization (MALDI) spectrometry. The presence of 1-amino 2-naphthol, one of the hypothesized degradation products, was confirmed using mass spectrometry.

  14. Uncertainty Analysis for Photovoltaic Degradation Rates (Poster)

    SciTech Connect

    Jordan, D.; Kurtz, S.; Hansen, C.

    2014-04-01

    Dependable and predictable energy production is the key to the long-term success of the PV industry. PV systems show over the lifetime of their exposure a gradual decline that depends on many different factors such as module technology, module type, mounting configuration, climate etc. When degradation rates are determined from continuous data the statistical uncertainty is easily calculated from the regression coefficients. However, total uncertainty that includes measurement uncertainty and instrumentation drift is far more difficult to determine. A Monte Carlo simulation approach was chosen to investigate a comprehensive uncertainty analysis. The most important effect for degradation rates is to avoid instrumentation that changes over time in the field. For instance, a drifting irradiance sensor, which can be achieved through regular calibration, can lead to a substantially erroneous degradation rates. However, the accuracy of the irradiance sensor has negligible impact on degradation rate uncertainty emphasizing that precision (relative accuracy) is more important than absolute accuracy.

  15. Critical factors in sonochemical degradation of fumaric acid.

    PubMed

    Wu, Zhilin; Cravotto, Giancarlo; Adrians, Marcus; Ondruschka, Bernd; Li, Weixin

    2015-11-01

    The effects of critical factors such as Henry's Law constant, atmospheric OH rate constant, initial concentration, H2O2, FeSO4 and tert-butanol on the sonochemical degradation of fumaric acid have been investigated. The pseudo first-order rate constant for the sonochemical degradation of 1mM fumaric acid is much lower than those for chloroform and phenol degradation, and is related to solute concentration at the bubble/water interface and reactivity towards hydroxyl radicals. Furthermore, fumaric acid is preferentially oxidized at the lower initial concentration. It is unreactive to H2O2 under agitation at room temperature. However, the degradation rate of fumaric acid increases with the addition of H2O2 under sonication. 0.1 mM of fumaric acid suppresses H2O2 formation thanks to water sonolysis, while degradation behavior is also dramatically affected by the addition of an oxidative catalyst (FeSO4) or radical scavenger (tert-butanol), indicating that the degradation of fumaric acid is caused by hydroxyl radicals generated during the collapse of high-energy cavities. PMID:26186831

  16. Analytical Improvements in PV Degradation Rate Determination

    SciTech Connect

    Jordan, D. C.; Kurtz, S. R.

    2011-02-01

    As photovoltaic (PV) penetration of the power grid increases, it becomes vital to know how decreased power output may affect cost over time. In order to predict power delivery, the decline or degradation rates must be determined accurately. For non-spectrally corrected data several complete seasonal cycles (typically 3-5 years) are required to obtain reasonably accurate degradation rates. In a rapidly evolving industry such a time span is often unacceptable and the need exists to determine degradation rates accurately in a shorter period of time. Occurrence of outliers and data shifts are two examples of analytical problems leading to greater uncertainty and therefore to longer observation times. In this paper we compare three methodologies of data analysis for robustness in the presence of outliers, data shifts and shorter measurement time periods.

  17. OXIDATIVE DEGRADATION OF ORGANIC ACIDS CONJUGATED WITH SULFITE OXIDATION IN FLUE GAS DESULFURIZATION

    EPA Science Inventory

    The report gives results of a study of organic acid degradation conjugated with sulfite oxidation under flue gas desulfurization (FGD) conditions. The oxidative degradation constant, k12, is defined as the ratio of organic acid degradation rate and sulfite oxidation rate times th...

  18. Overview of Field Experience - Degradation Rates & Lifetimes

    SciTech Connect

    Jordan, Dirk; Kurtz, Sarah

    2015-09-14

    The way a PV module fails may depend not only on its design and the materials used in its construction, but also on the weather it experiences, the way it is mounted, and the quality control during its manufacture. This presentation gives an overview of Field Experience - what degradation rates and what lifetimes are being observed in various regions.

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

    PubMed

    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

  20. Synthesis and degradation test of hyaluronic acid hydrogels.

    PubMed

    Hahn, Sei Kwang; Park, Jung Kyu; Tomimatsu, Takashi; Shimoboji, Tsuyoshi

    2007-03-10

    Hyaluronic acid (HA) hydrogels prepared with three different crosslinking reagents were assessed by in vitro and in vivo degradation tests for various tissue engineering applications. Adipic acid dihydrazide grafted HA (HA-ADH) was synthesized and used for the preparation of methacrylated HA (HA-MA) with methacrylic anhydride and thiolated HA (HA-SH) with Traut's reagent (imminothiolane). (1)H NMR analysis showed that the degrees of HA-ADH, HA-MA, and HA-SH modification were 69, 29, and 56 mol%, respectively. HA-ADH hydrogel was prepared by the crosslinking with bis(sulfosuccinimidyl) suberate (BS(3)), HA-MA hydrogel with dithiothreitol (DTT) by Michael addition, and HA-SH hydrogel with sodium tetrathionate by disulfide bond formation. According to in vitro degradation tests, HA-SH hydrogel was degraded very fast, compared to HA-ADH and HA-MA hydrogels. HA-ADH hydrogel was degraded slightly faster than HA-MA hydrogel. Based on these results, HA-MA hydrogels and HA-SH hydrogels were implanted in the back of SD rats and their degradation was assessed according to the pre-determined time schedule. As expected from the in vitro degradation test results, HA-SH hydrogel was in vivo degraded completely only in 2 weeks, whereas HA-MA hydrogels were degraded only partially even in 29 days. The degradation rate of HA hydrogels were thought to be controlled by changing the crosslinking reagents and the functional group of HA derivatives. In addition, the state of HA hydrogel was another factor in controlling the degradation rate. Dried HA hydrogel at 37 degrees C for a day resulted in relatively slow degradation compared to the bulk HA hydrogel. There was no adverse effect during the in vivo tests. PMID:17101173

  1. Water and UV degradable lactic acid polymers

    SciTech Connect

    Bonsignore, P.V.; Coleman, R.D.

    1990-06-26

    A water and UV light degradable copolymer of monomers of lactic acid and a modifying monomer selected from the class consisting of ethylene and polyethylane glycols (PVB 6/22/90), propylene and and polypropylene (PVB 6/22/90) glycols, P-dioxanone, 1, 5 dioxepan-2-one, 1,4 -oxathialan-2-one, 1,4-dioxide and mixtures thereof. These copolymers are useful for waste disposal and agricultural purposes. Also disclosed is a water degradable blend of polylactic acid or modified polylactic acid and high molecular weight polyethylene oxide wherein the high molecular weight polyethylene oxide is present in the range of from about 2% by weight to about 50% by weight, suitable for films. A method of applying an active material selected from the class of seeds, seedlings, pesticides, herbicides, fertilizers and mixtures thereof to an agricultural site is also disclosed.

  2. Water and UV degradable lactic acid polymers

    DOEpatents

    Bonsignore, P.V.; Coleman, R.D.

    1994-11-01

    A water and UV light degradable copolymer of monomers of lactic acid and a modifying monomer were selected from the class consisting of ethylene and polyethylene glycols, propylene and polypropylene glycols, P-dioxanone, 1,5 dioxepan-2-one, 1,4 -oxathialan-2-one, 1,4-dioxide and mixtures. These copolymers are useful for waste disposal and agricultural purposes. Also disclosed is a water degradable blend of polylactic acid or modified polylactic acid and high molecular weight polyethylene oxide where the high molecular weight polyethylene oxide is present in the range of from about 2% by weight to about 50% by weight, suitable for films. A method of applying an active material selected from the class of seeds, seedlings, pesticides, herbicides, fertilizers and mixtures to an agricultural site is also disclosed.

  3. Water and UV degradable lactic acid polymers

    DOEpatents

    Bonsignore, P.V.; Coleman, R.D.

    1996-10-08

    A water and UV light degradable copolymer is described made from monomers of lactic acid and a modifying monomer selected from the class consisting of ethylene glycol, propylene glycol, P-dioxanone, 1,5 dioxepan-2-one, 1,4-oxathialan-2-one, 1,4-dioxide and mixtures thereof. These copolymers are useful for waste disposal and agricultural purposes. Also disclosed is a water degradable blend of polylactic acid or modified polylactic acid and high molecular weight polyethylene oxide wherein the high molecular weight polyethylene oxide is present in the range of from about 2 by weight to about 50% by weight, suitable for films. A method of applying an active material selected from the class of seeds, seedlings, pesticides, herbicides, fertilizers and mixtures thereof to an agricultural site is also disclosed.

  4. Water and UV degradable lactic acid polymers

    DOEpatents

    Bonsignore, Patrick V.; Coleman, Robert D.

    1996-01-01

    A water and UV light degradable copolymer of monomers of lactic acid and a modifying monomer selected from the class consisting of ethylene glycol, propylene glycol, P-dioxanone, 1,5 dioxepan-2-one, 1,4-oxathialan-2-one, 1,4-dioxide and mixtures thereof. These copolymers are useful for waste disposal and agricultural purposes. Also disclosed is a water degradable blend of polylactic acid or modified polylactic acid and high molecular weight polyethylene oxide wherein the high molecular weight polyethylene oxide is present in the range of from about 2 by weight to about 50% by weight, suitable for films. A method of applying an active material selected from the class of seeds, seedlings, pesticides, herbicides, fertilizers and mixtures thereof to an agricultural site is also disclosed.

  5. Water and UV degradable lactic acid polymers

    DOEpatents

    Bonsignore, Patrick V.; Coleman, Robert D.

    1994-01-01

    A water and UV light degradable copolymer of monomers of lactic acid and a modifying monomer selected from the class consisting of ethylene and polyethylene glycols, propylene and polypropylene glycols, P-dioxanone, 1,5 dioxepan-2-one, 1,4 -oxathialan-2-one, 1,4-dioxide and mixtures thereof. These copolymers are useful for waste disposal and agricultural purposes. Also disclosed is a water degradable blend of polylactic acid or modified polylactic acid and high molecular weight polyethylene oxide wherein the high molecular weight polyethylene oxide is present in the range of from about 2% by weight to about 50% by weight, suitable for films. A method of applying an active material selected from the class of seeds, seedlings, pesticides, herbicides, fertilizers and mixtures thereof to an agricultural site is also disclosed.

  6. Anaerobic degradation of linoleic oleic acids

    SciTech Connect

    Lalman, J.A.; Bagley, D.M.

    1999-07-01

    The anaerobic degradation of linoleic (C18:2) and oleic (C18:1) acids was examined in batch experiments. By-product distribution depended on both the type of long chain fatty acid added and initial substrate concentration. Major by-products were palmitic (C16), myristic (C14) and acetic acids. Trace quantities of palmitoleic (C16:1) and lauric (C12) acids were observed together with larger amounts of palmitic (C16), myristic (C14) and hexanoic (C6) acids in cultures incubated with 100 mg/L linoleic (C18:2) acid. Bio-hydrogenation of C18 fatty acids was not necessary for the {beta}-oxidation mechanism to proceed. Aceticlastic methanogenic inhibition was observed in cultures inoculated with greater than 50 mg/L linoleic (C18:2) acid. In cultures incubated with greater than 50 mg/L oleic (C18:1) acid, aceticlastic methanogenic inhibition was observed for a short time period.

  7. EFFECT OF TRACE METALS AND SULFITE OXIDATION OF ADIPIC ACID DEGRADATION IN FGD SYSTEMS

    EPA Science Inventory

    The report gives results of the measurement of the adipic acid degradation rate in a bench-scale flue gas desulfurization (FGD) system, designed to simulate many of the important aspects of full-scale FGD systems. Results show that the adipic acid degradation rate depends on the ...

  8. Aerobic Microbial Degradation of Glucoisosaccharinic Acid

    PubMed Central

    Strand, S. E.; Dykes, J.; Chiang, V.

    1984-01-01

    α-Glucoisosaccharinic acid (GISA), a major by-product of kraft paper manufacture, was synthesized from lactose and used as the carbon source for microbial media. Ten strains of aerobic bacteria capable of growth on GISA were isolated from kraft pulp mill environments. The highest growth yields were obtained with Ancylobacter spp. at pH 7.2 to 9.5. GISA was completely degraded by cultures of an Ancylobacter isolate. Ancylobacter cell suspensions consumed oxygen and produced carbon dioxide in response to GISA addition. A total of 22 laboratory strains of bacteria were tested, and none was capable of growth on GISA. GISA-degrading isolates were not found in forest soils. Images PMID:16346467

  9. [Microbial degradation of 3-phenoxybenzoic acid--A review].

    PubMed

    Deng, Weiqin; Liu, Shuliang; Yao, Kai

    2015-09-01

    3-phenoxybenzoic acid (3-PBA) with estrogen toxicity is one of the intermediate products of most pyrethroid pesticides. 3-PBA is difficult to degrade in the natural environment, and threatens food safety and human health. Microbial degradation of pyrethroids and their intermediate product (3-PBA) has become a hot topic in recent years. Here, we reviewed microbial species, degrading enzymes and degradation genes, degradation pathways of 3-PBA degrading and the application of 3-PBA degradation strains. This article provides references for the study of 3-PBA degradation by microorganisms. PMID:26762020

  10. Degradation and Isotope Source Tracking of Glyphosate and Aminomethylphosphonic Acid.

    PubMed

    Li, Hui; Joshi, Sunendra R; Jaisi, Deb P

    2016-01-27

    Glyphosate [N-(phosphonomethyl) glycine], an active ingredient of the herbicide Roundup, and its main metabolite, aminomethylphosphonic acid (AMPA), have been frequently reported to be present in soils and other environments and thus have heightened public concerns on their potential adverse effects. Understanding the fate of these compounds and differentiating them from other naturally occurring compounds require a toolbox of methods that can go beyond conventional methods. Here, we applied individual isotope labeling technique whereby each compound or mineral involved in the glyphosate and AMPA degradation reaction was either synthesized or chosen to have distinct (18)O/(16)O ratios so that the source of incorporated oxygen in the orthophosphate generated and corresponding isotope effect during C-P bond cleavage could be identified. Furthermore, we measured original isotope signatures of a few commercial glyphosate sources to identify their source-specific isotope signatures. Our degradation kinetics results showed that the rate of glyphosate degradation was higher than that of AMPA in all experimental conditions, and both the rate and extent of degradation were lowest under anoxic conditions. Oxygen isotope ratios (δ(18)OP) of orthophosphate generated from glyphosate and AMPA degradation suggested that one external oxygen atom from ambient water, not from dissolved oxygen or mineral, was incorporated into orthophosphate with the other three oxygen atoms inherited from the parent molecule. Interestingly, δ(18)OP values of all commercial glyphosate products studied were found to be the lightest among all orthophosphates known so far. Furthermore, isotope composition was found to be unaffected due to variable degradation kinetics, light/dark, and oxic/anoxic conditions. These results highlight the importance of phosphate oxygen isotope ratios as a nonconventional tool to potentially distinguish glyphosate sources and products from other organophosphorus compounds

  11. Effect of trace metals and sulfite oxidation of adipic acid degradation in FGD systems. Final report Dec 81-May 82

    SciTech Connect

    Jarvis, J.B.; Terry, J.C.; Schubert, S.A.; Utley, B.L.

    1982-12-01

    The report gives results of the measurement of the adipic acid degradation rate in a bench-scale flue gas desulfurization (FGD) system, designed to simulate many of the important aspects of full-scale FGD systems. Results show that the adipic acid degradation rate depends on the sulfite oxidation rate, the adipic acid concentration, the presence of manganese in solution, and temperature. The degradation rate is also affected by pH, but only when manganese is present. Adipic acid degradation products identified in the liquid phase include valeric, butyric, propionic, succinic, and glutaric acids. When manganese was present, the predominant degradation products were succinic and glutaric acids. Analysis of solids from the bench scale tests shows large concentrations of coprecipitated adipic acid in low oxidation sulfite solids. By contrast, low quantities of coprecipitated adipic acid were found in high oxidation gypsum solids.

  12. Cellulose degradation in alkaline media upon acidic pretreatment and stabilisation.

    PubMed

    Testova, Lidia; Nieminen, Kaarlo; Penttilä, Paavo A; Serimaa, Ritva; Potthast, Antje; Sixta, Herbert

    2014-01-16

    The present study reports on a revised kinetic model for alkaline degradation of cellulose accounting for primary peeling/stopping reactions as well as for alkaline hydrolysis followed by secondary peeling. Oxalic acid pretreated cotton linters was utilised as the model substrate for the prehydrolysis-soda anthraquinone process. The main emphasis was investigating the effect of end-group stabilising additives such as sodium borohydride (BH), anthraquinone (AQ), and anthraquinone-2-sulphonic acid sodium salt (AQS) on the rates of the yield loss reactions. BH and AQS ensured a cellulose yield gain of 13% and 11%, respectively, compared to the reference. Both stabilisation agents decreased the content of the reducing end groups in the samples, while in the case of AQS stabilisation a 25% increase in carboxyl group content compared to the reference was also observed. As expected, the addition of end group stabilisers resulted in a significant decrease in the peeling-to-stopping rate constants ratio. PMID:24188853

  13. Evaluation of non-thermal effects of electricity on ascorbic acid and carotenoid degradation in acerola pulp during ohmic heating.

    PubMed

    Jaeschke, Débora Pez; Marczak, Ligia Damasceno Ferreira; Mercali, Giovana Domeneghini

    2016-05-15

    The effect of electric field on ascorbic acid and carotenoid degradation in acerola pulp during ohmic heating was evaluated. Ascorbic acid kinetic degradation was evaluated at 80, 85, 90 and 95°C during 60 min of thermal treatment by ohmic and conventional heating. Carotenoid degradation was evaluated at 90 and 95°C after 50 min of treatment. The different temperatures evaluated showed the same effect on degradation rates. To investigate the influence of oxygen concentration on the degradation process, ohmic heating was also carried out under rich and poor oxygen modified atmospheres at 90°C. Ascorbic acid and carotenoid degradation was higher under a rich oxygen atmosphere, indicating that oxygen is the limiting reagent of the degradation reaction. Ascorbic acid and carotenoid degradation was similar for both heating technologies, demonstrating that the presence of the oscillating electric field did not influence the mechanisms and rates of reactions associated with the degradation process. PMID:26775953

  14. The abiotic degradation of soil organic matter to oxalic acid

    NASA Astrophysics Data System (ADS)

    Studenroth, Sabine; Huber, Stefan; Schöler, H. F.

    2010-05-01

    degradation of catechol to oxalic acid delivers a maximum yield of approximately 60 %, whereas the presence of chloride reduces the formation of oxalic acid to 30 %. Chloride possibly induces further competing reactions of catechol leading to a lower concentration of oxalic acid. Freeze-dried soil samples have been tested for production of oxalic acid, where the rate of organic matter seems to play an important role for the formation. By adding iron (III) and/or hydrogen peroxide oxalic acid yields increase, which demonstrates the reaction of soil organic matter with iron (III) and hydrogen peroxide as expected. Thus the natural abiotic formation of oxalic acid is confirmed. The results of the soil measurements are similar to those obtained with catechol. Therefore, the newly gained insights with model compounds appear to be applicable to soil conditions and these findings increase our understanding of the degradation pathways of soil organic matter. Furthermore an overview of the rates of oxalic acid formation of a variety of soil samples is shown and discussed in the light of different soil parameter.

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

    NASA Astrophysics Data System (ADS)

    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.

  16. Efficient sonochemical degradation of perfluorooctanoic acid using periodate.

    PubMed

    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 45 mM PI, 96.5% of PFOA was decomposed with a defluorination efficiency of 95.7% after 120 min 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

  17. TiO2 Photocatalytic Degradation of Phenylarsonic Acid

    PubMed Central

    Zheng, Shan; Cai, Yong; O’Shea, Kevin E.

    2010-01-01

    Phenyl substituted arsenic compounds are widely used as feed additives in the poultry industry and have become a serious environmental concern. We have demonstrated that phenylarsonic acid (PA) is readily degraded by TiO2 photocatalysis. Application of the Langmuir–Hinshelwood kinetic model for the initial stages of the TiO2 photocatalysis of PA yields an apparent rate constant (kr) of 2.8 µmol/L·min and the pseudo-equilibrium constant (K) for PA is 34 L/mmol. The pH of the solution influences the adsorption and photocatalytic degradation of PA due to the surface charge of TiO2 photocatalyst and speciation of PA. Phenol, catechol and hydroquinone are observed as the predominant products during the degradation. The roles of reactive oxygen species, •OH, 1O2, O2−• and hVB+ were probed by adding appropriate scavengers to the reaction medium and the results suggest that •OH plays a major role in the degradation of PA. By-products studies indicate the surface of the catalyst plays a key role in the formation of the primary products and the subsequent oxidation pathways leading to the mineralization to inorganic arsenic. TiO2 photocatalysis results in the rapid destruction of PA and may be attractive for the remediation of a variety of organoarsenic compounds. PMID:20473340

  18. Photolytic and photocatalytic degradation of 6-chloronicotinic acid.

    PubMed

    Zabar, Romina; Dolenc, Darko; Jerman, Tina; Franko, Mladen; Trebše, Polonca

    2011-10-01

    This work describes for the first time the photolytic and photocatalytic degradation of 6-chloronicotinic acid (6CNA) in double deionised water, which is a degradation product of neonicotinoid insecticides imidacloprid and acetamiprid, and it is known to appear in different environmental matrices. Photolytic experiments were performed with three UVA (ultraviolet A) polychromatic fluorescent lamps with broad maximum at 355 nm, while photocatalytic experiments were performed using immobilised titanium dioxide (TiO₂) on six glass slides in the spinning basket inside a photocatalytic quartz cell under similar irradiation conditions. Photolytic degradation revealed no change in concentration of 6CNA within 120 min of irradiation, while the photocatalytic degradation within 120 min, obeyed first-order kinetics. The observed disappearance rate constant was k=0.011 ± 0.001 min⁻¹ and t½ was 63.1 ± 5.5 min. Mineralisation rate was estimated through total organic carbon (TOC) and measurements revealed no carbon removal in case of photolysis after 120 min of exposure. However in photocatalytic experiments 46 ± 7% mineralisation was achieved within 120 min of irradiation. Nevertheless, the removal of total nitrogen (TN) was not observed across all experiments. Ion chromatographic analyses indicated transformation of chlorine atoms to chloride and increase of nitrate(V) ions only via photocatalytic experiments. Efficiency of selected advanced oxidation process (AOP) was investigated through toxicity assessment with Vibrio fischeri luminescent bacteria and revealed higher adverse effects of treated samples on bacteria following photocatalytic degradation in spite of the fact that higher mineralisation was achieved. New hydroxylated product generated in photocatalytic experiments with TiO₂, was confirmed with liquid chromatography-electro spray ionisation mass spectrometry (LC-ESI-MS/MS) analyses, gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic

  19. Degradation study of carnosic acid, carnosol, rosmarinic acid, and rosemary extract (Rosmarinus officinalis L.) assessed using HPLC.

    PubMed

    Zhang, Ying; Smuts, Jonathan P; Dodbiba, Edra; Rangarajan, Rekha; Lang, John C; Armstrong, Daniel W

    2012-09-12

    Rosemary, whose major caffeoyl-derived and diterpenoid ingredients are rosmarinic acid, carnosol, and carnosic acid, is an important source of natural antioxidants and is being recognized increasingly as a useful preservative, protectant, and even as a potential medicinal agent. Understanding the stability of these components and their mode of interaction in mixtures is important if they are to be utilized to greatest effect. A study of the degradation of rosmarinic acid, carnosol, carnosic acid, and a mixture of the three was conducted in ethanolic solutions at different temperatures and light exposure. As expected, degradation increased with temperature. Some unique degradation products were formed with exposure to light. Several degradation products were reported for the first time. The degradation products were identified by HPLC/MS/MS, UV, and NMR. The degradation of rosemary extract in fish oil also was investigated, and much slower rates of degradation were observed for carnosic acid. In the mixture of the three antioxidants, carnosic acid serves to maintain levels of carnosol, though it does so at least in part at the cost of its own degradation. PMID:22881034

  20. Hydrolytic degradation study of biodegradable polyesteramide copolymers based on epsilon-caprolactone and 11-aminoundecanoic acid.

    PubMed

    Qian, Zhiyong; Li, Sai; He, Yi; Zhang, Hailian; Liu, Xiaobo

    2004-05-01

    In this paper, a new kind of aliphatic biodegradable polyesteramide copolymers P(CL/AU)x/y based on epsilon-caprolactone and 11-aminoundecanoic acid were synthesized by the melt polycondensation method. Hydrolytic degradation behavior of P(CL/AU) copolymers were studied by using FTIR, 1H-NMR and DSC. Chemical compositions, macromolecular weight, thickness of the test sample, and pH of the degradation medium have great effect on degradation rate. The degradation rate decreased with increase in aminoundecanoic acid content, macromolecular weight, and thickness of the test samples, but increased with incubation temperature and pH of the degradation medium. The degradation mechanism was studied according to the mathematical model developed by professor Göpferich. PMID:14741611

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

    PubMed

    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

  2. Fatty Acid Structure and Degradation Analysis in Fingerprint Residues

    NASA Astrophysics Data System (ADS)

    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.

  3. Oxidative degradation of organic acids conjugated with sulfite oxidation in flue gas desulfurization

    SciTech Connect

    Lee, Y.I.

    1986-01-01

    Organic acid degradation conjugated with sulfite oxidation has been studied under flue gas desulfurization (EGD) conditions. The oxidative degradation constant, k/sub 12/, is defined as the ratio of organic acid degradation rate and sulfite oxidation rate after being normalized by the concentrations of organic acid and dissolved S(IV). K/sub 12/, not significantly affected by pH or dissolved oxygen, is around 10/sup -3/ in the absence of manganese or iron. However, k/sub 12/ is increased by certain transition metals such as Co, Ni, and Fe and is decreased by Mn and halides. Lower dissolved S(IV) magnified these effects. No k/sub 12/ greater than 4 x 10/sup -3/ or smaller than 0.1 x 10/sup -3/ has been observed. A free radical mechanism was proposed to describe the kinetics: (1) sulfate free radical is the major radical responsible to the degradation of organic acid; (2) ferrous generates sulfate radical by reacting with monoxypersulfate to enhance k/sub 12/; (3) manganous consumes sulfate radical to decrease k/sub 12/; (4) dissolved S(IV) competes with ferrous for monoxypersulfate and with manganous for sulfate radical to demonstrate the effects of dissolved S(IV) on k/sub 12/. Hydroxy and sulfonated carboxylic acids degrade approximately three times slower than saturated dicarboxylic acids; while maleic acid, an unsaturated dicarboxylic acid, degraded an order of magnitude faster. A wide spectrum of degradation products of adipic acid were found, including carbon dioxide - the major product, glutaric semialdehyde - the major retained product with low manganese, glutaric acid and valeric acids - the major retained product with high manganese, lower molecular weight mono- and dicarboxylic acids, other carbonyl compounds, and hydrocarbons.

  4. SENSITIVITY ANALYSIS OF A TPB DEGRADATION RATE MODEL

    SciTech Connect

    Crawford, C; Tommy Edwards, T; Bill Wilmarth, B

    2006-08-01

    A tetraphenylborate (TPB) degradation model for use in aggregating Tank 48 material in Tank 50 is developed in this report. The influential factors for this model are listed as the headings in the table below. A sensitivity study of the predictions of the model over intervals of values for the influential factors affecting the model was conducted. These intervals bound the levels of these factors expected during Tank 50 aggregations. The results from the sensitivity analysis were used to identify settings for the influential factors that yielded the largest predicted TPB degradation rate. Thus, these factor settings are considered as those that yield the ''worst-case'' scenario for TPB degradation rate for Tank 50 aggregation, and, as such they would define the test conditions that should be studied in a waste qualification program whose dual purpose would be the investigation of the introduction of Tank 48 material for aggregation in Tank 50 and the bounding of TPB degradation rates for such aggregations.

  5. Rate-based degradation modeling of lithium-ion cells

    SciTech Connect

    E.V. Thomas; I. Bloom; J.P. Christophersen; V.S. Battaglia

    2012-05-01

    Accelerated degradation testing is commonly used as the basis to characterize battery cell performance over a range of stress conditions (e.g., temperatures). Performance is measured by some response that is assumed to be related to the state of health of the cell (e.g., discharge resistance). Often, the ultimate goal of such testing is to predict cell life at some reference stress condition, where cell life is defined to be the point in time where performance has degraded to some critical level. These predictions are based on a degradation model that expresses the expected performance level versus the time and conditions under which a cell has been aged. Usually, the degradation model relates the accumulated degradation to the time at a constant stress level. The purpose of this article is to present an alternative framework for constructing a degradation model that focuses on the degradation rate rather than the accumulated degradation. One benefit of this alternative approach is that prediction of cell life is greatly facilitated in situations where the temperature exposure is not isothermal. This alternative modeling framework is illustrated via a family of rate-based models and experimental data acquired during calendar-life testing of high-power lithium-ion cells.

  6. Degradation of hop bitter acids by fungi

    SciTech Connect

    Huszcza, Ewa Bartmanska, Agnieszka; Aniol, Miroslaw; Maczka, Wanda; Zolnierczyk, Anna; Wawrzenczyk, Czeslaw

    2008-07-01

    Nine fungal strains related to: Trametes versicolor, Nigrospora oryzae, Inonotus radiatus, Crumenulopsis sororia, Coryneum betulinum, Cryptosporiopsis radicicola, Fusarium equiseti, Rhodotorula glutinis and Candida parapsilosis were tested for their ability to degrade humulones and lupulones. The best results were obtained for T. versicolor culture, in which humulones and lupulones were fully degraded after 4 days of incubation in the dark or after 36 h in the light. The experiments were performed on a commercial hop extract and on sterilized spent hops.

  7. Degradation of h-acid by free and immobilized cells of Alcaligenes latus

    PubMed Central

    Usha, M.S.; Sanjay, M.K.; Gaddad, S.M.; Shivannavar, C.T.

    2010-01-01

    Alcaligenes latus, isolated from industrial effluent, was able to grow in mineral salts medium with 50 ppm (0.15 mM) of H-acid as a sole source of carbon. Immobilization of Alcaligenes latus in Ca-alginate and polyurethane foam resulted in cells embedded in the matrices. When free cells and immobilized cells were used for biodegradation studies at concentration ranging from 100 ppm (0.3 mM) to 500 ppm (1.15 mM) degradation rate was enhanced with immobilized cells. Cells immobilized in polyurethane foam showed 100% degradation up to 350 ppm (1.05 mM) and 57% degradation at 500 ppm (1.5 mM). Degradation rate of Ca-alginate immobilized cells was less as compared to that of polyurethane foam immobilized cells. With Ca-alginate immobilized cells 100% degradation was recorded up to 200 ppm (0.6 mM) of H-acid and only 33% degradation was recorded at 500 ppm (1.5 mM) of H-acid. Spectral analysis of the products after H-acid utilization showed that the spent medium did not contain any aromatic compounds indicating H-acid degradation by A. latus. PMID:24031573

  8. Light-induced degradation of perfluorocarboxylic acids in the presence of titanium dioxide.

    PubMed

    Dillert, Ralf; Bahnemann, Detlef; Hidaka, Hisao

    2007-03-01

    The UV-photon-induced degradation of heptafluorobutanoic acid was investigated in acidic aqueous solutions in the presence of titanium dioxide. Heptafluorobutanoic acid could be degraded with this photocatalyst in a light-induced reaction generating carbon dioxide and fluoride anions. Carbon dioxide evolution in a significant amount occurred only in the presence of molecular oxygen and the photocatalyst. The light-induced degradation of trifluoroacetic acid, pentafluoropropanoic acid, nonafluorobutanoic acid, pentadecafluorooctanoic acid, nonafluorobutanesulfonic acid, and heptadecafluorooctanesulfonic acid in the presence of titanium dioxide was also studied. The perfluorocarboxylic acids under investigation are degraded to generate CO(2) and fluoride anions while both perfluorinated sulfonic acids are persistent under the experimental conditions employed in this study. For all compounds photonic efficiencies of the mineralization reaction were estimated to be smaller than 1x10(-5). To increase the photocatalytic activity mixed systems containing homogeneous phosphotungstic acid and heterogeneous titanium dioxide catalysts were also investigated. In the mixtures of these two photocatalysts, the formation rate of CO(2) increased with illumination time. PMID:17126882

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

    SciTech Connect

    Gutberlet, T.; Hilbig, H.; Beddoe, R.E.

    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.

  10. Effect of cyclodextrins on the degradation rate of benzylpenicillin.

    PubMed

    Popielec, A; Fenyvesi, É; Yannakopoulou, K; Loftsson, T

    2016-02-01

    The effect of cyclodextrin (CD) inclusion complexes on the degradation of benzylpenicillin in aqueous solutions was investigated at several different pH values and 37°C. The effects of neutral as well as both positively and negatively charged CDs were evaluated; all together 13 different CDs. Kinetic studies with HPβCD and RMβCD at pH ranging from 1.2 to 9.6 showed that CDs have stabilizing effect on the β-lactam ring in aqueous acidic media but generally accelerated the hydrolytic cleavage of the β-lactam ring in neutral and basic media. At physiologic pH (pH 7.4) quaternary ammonium CD derivatives (i.e., positively charged CD derivatives) have the highest catalytic effect, resulting in 6- to 18-fold enhancement of hydrolysis rate, while both the neutral methylated CDs had much less effect, resulting in 2- to 3-fold enhancement, and the negatively charged CD derivatives, resulting in only about 1.1- to 1.2-fold enhancement in the hydrolytic cleavage of the β-lactam ring. Addition of water-soluble polymers to the aqueous reaction media containing CDs was shown to decrease the catalyzing effects of CDs on the β-lactam hydrolysis. PMID:27004370

  11. Accelerating degradation rate of pure iron by zinc ion implantation.

    PubMed

    Huang, Tao; Zheng, Yufeng; Han, Yong

    2016-12-01

    Pure iron has been considered as a promising candidate for biodegradable implant applications. However, a faster degradation rate of pure iron is needed to meet the clinical requirement. In this work, metal vapor vacuum arc technology was adopted to implant zinc ions into the surface of pure iron. Results showed that the implantation depth of zinc ions was about 60 nm. The degradation rate of pure iron was found to be accelerated after zinc ion implantation. The cytotoxicity tests revealed that the implanted zinc ions brought a slight increase on cytotoxicity of the tested cells. In terms of hemocompatibility, the hemolysis of zinc ion implanted pure iron was lower than 2%. However, zinc ions might induce more adhered and activated platelets on the surface of pure iron. Overall, zinc ion implantation can be a feasible way to accelerate the degradation rate of pure iron for biodegradable applications. PMID:27482462

  12. Accelerating degradation rate of pure iron by zinc ion implantation

    PubMed Central

    Huang, Tao; Zheng, Yufeng; Han, Yong

    2016-01-01

    Pure iron has been considered as a promising candidate for biodegradable implant applications. However, a faster degradation rate of pure iron is needed to meet the clinical requirement. In this work, metal vapor vacuum arc technology was adopted to implant zinc ions into the surface of pure iron. Results showed that the implantation depth of zinc ions was about 60 nm. The degradation rate of pure iron was found to be accelerated after zinc ion implantation. The cytotoxicity tests revealed that the implanted zinc ions brought a slight increase on cytotoxicity of the tested cells. In terms of hemocompatibility, the hemolysis of zinc ion implanted pure iron was lower than 2%. However, zinc ions might induce more adhered and activated platelets on the surface of pure iron. Overall, zinc ion implantation can be a feasible way to accelerate the degradation rate of pure iron for biodegradable applications. PMID:27482462

  13. Structure of aldobiouronic acid and glucuronic acid from Agathis australis degraded gum polysaccharide.

    PubMed

    Singh, R B

    2007-04-01

    Agathis australis gum on acid hydrolysis with sulphuric acid yielded L-arabinose and D-galactose in 1:4 molar ratio with traces of L-fucose. The components of aldobiouronic acid and glucuronic acid were obtained by graded hydrolysis of degraded gum polysaccharide. The derivatives of aldobiouronic acid was obtained as methyl ester methyl glycoside. PMID:17915743

  14. Nitrogen fixation rates in algal turf communities of a degraded versus less degraded coral reef

    NASA Astrophysics Data System (ADS)

    den Haan, Joost; Visser, Petra M.; Ganase, Anjani E.; Gooren, Elfi E.; Stal, Lucas J.; van Duyl, Fleur C.; Vermeij, Mark J. A.; Huisman, Jef

    2014-12-01

    Algal turf communities are ubiquitous on coral reefs in the Caribbean and are often dominated by N2-fixing cyanobacteria. However, it is largely unknown (1) how much N2 is actually fixed by turf communities and (2) which factors affect their N2 fixation rates. Therefore, we compared N2 fixation activity by turf communities at different depths and during day and night-time on a degraded versus a less degraded coral reef site on the island of Curaçao. N2 fixation rates measured with the acetylene reduction assay were slightly higher in shallow (5-10-m depth) than in deep turf communities (30-m depth), and N2 fixation rates during the daytime significantly exceeded those during the night. N2 fixation rates by the turf communities did not differ between the degraded and less degraded reef. Both our study and a literature survey of earlier studies indicated that turf communities tend to have lower N2 fixation rates than cyanobacterial mats. However, at least in our study area, turf communities were more abundant than cyanobacterial mats. Our results therefore suggest that turf communities play an important role in the nitrogen cycle of coral reefs. N2 fixation by turfs may contribute to an undesirable positive feedback that promotes the proliferation of algal turf communities while accelerating coral reef degradation.

  15. Amino Acid Degradation after Meteoritic Impact Simulation

    NASA Technical Reports Server (NTRS)

    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.

  16. Benzoic acid degradation of polyacrylonitrile fibers

    NASA Technical Reports Server (NTRS)

    Varma, D. S.; Needles, H. L.; Cagliostro, D. E.

    1981-01-01

    The reactions of polyacrylonitrile (PAN) fibers in the presence of benzoic acid have been studied. Polyacrylonitrile fibers oxidize more readily in the presence of benzoic acid than in air at temperatures in the range of 170 C. The product decreased in solubility with extent of reaction. Gel permeation chromatography of the soluble fraction showed change in polydispersity. The insoluble product exhibited differences in weight loss as a function of decomposition temperature compared to PAN fibers. Infrared analyses of the fiber product showed absorption peaks similar to air-oxidized PAN. High-energy photoelectron spectral analysis showed a carbon-rich surface which contained oxygen and nitrogen. An air oxidized sample of fiber contained more oxygen at the surface than a fiber treated first with benzoic acid and then air oxidized.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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. Chemical Degradation Studies on a Series of Dithiophosphinic Acids

    SciTech Connect

    Freiderich, Melissa E; Delmau, Laetitia Helene; Peterman, D. R.; Marc, Philippe L; Klaehn, John D.

    2014-01-01

    In this study a significant increase in the stability of a series of dithiophosphinic acids (DPAHs) under oxidizing acidic conditions was achieved. The degradation behavior of a series of DPAHs, designed for lanthanide/actinide separation, was examined. The stability of the DPAHs, when contacted with varying nitric acid concentrations, was tested and monitored using 31P {1H} NMR. Changes in the functional groups of the DPAHs resulted in substantial increases in the stability. However, all the DPAHs eventually showed signs of degradation when placed in contact with 2 M HNO3. The addition of a radical scavenger, hydrazine, inhibited the degradation of the DPAHs. With small amounts of hydrazine, five of the DPAHs remained stable for over a month in direct contact with 2 M HNO3.

  20. Chemical Degradation Studies on a Series of Dithiophosphinic Acids

    SciTech Connect

    Melissa E. Freiderich; Dean R. Peterman; John R. Klaehn; Philippe Marc; Laetitia H. Delmau

    2014-04-01

    A significant increase in the stability of a series of dithiophosphinic acids (DPAHs) under oxidizing acidic conditions was achieved. The degradation behavior of a series of DPAHs, designed for lanthanide/actinide separation, was examined. The stability of the DPAHs, when contacted with varying nitric acid concentrations, was tested and monitored using 31P {1H} NMR. Changes in the functional groups of the DPAHs resulted in substantial increases in the stability. However, when placed in contact with 2 M HNO3 all the DPAHs eventually showed signs of degradation. The addition of a radical scavenger, hydrazine, inhibited the degradation of the DPAHs. In the presence of a small concentration of hydrazine, five of the DPAHs remained stable for over a month in direct contact with 2 M HNO3.

  1. Activated sludge degradation of adipic acid esters.

    PubMed Central

    Saeger, V W; Kalley, R G; Hicks, O; Tucker, E S; Mieure, J P

    1976-01-01

    The biodegradability of three aliphatic adipic acid diesters and a 1,3-butylene glycol adipic acid polyester was determined in acclimated, activated sludge systems. Rapid primary biodegradation from 67 to 99+% was observed at 3- and 13-mg/liter feed levels for di-n-hexyl adipate, di(2-ethylhexyl) adipate, and di(heptyl, nonyl) adipate in 24 h. When acclimated, activated sludge microorganisms were employed as the seed for two carbon dioxide evolution procedures, greater than 75% of the theoretical carbon dioxide was evolved for the three diesters and the polyester in a 35-day test period. The essentially complete biodegradation observed in these studies suggests that these esters would not persist when exposed to similar mixed microbial populations in the environment. PMID:1275494

  2. A degradation study of PLLA containing lauric acid.

    PubMed

    Renouf-Glauser, Annette C; Rose, John; Farrar, David; Cameron, Ruth E

    2005-05-01

    Addition of lauric acid to poly (L-lactide) (PLLA) has resulted in a new family of enhanced degradation biomaterials. Presented is PLLA4.5 (PLLA containing 4.5 wt% lauric acid), the fastest degrading of the family. Degradation was studied via mass changes, gel-permeation chromatography, wide- and small-angle X-ray scattering (WAXS and SAXS), simultaneous SAXS and tensile testing, and visual observation. The undegraded PLLA4.5 deformed by crazing, recognisable from the characteristic shape of the SAXS pattern. As water up-take and degradation proceeded, samples crystallised, decreasing the SAXS long period, until by 4 days the deformation mechanism had become that of crystal-mediated deformation. This resulted in a 'peanut-lemon'-shaped SAXS pattern, interpreted in terms of cavitation and fibrillated shear. Further degradation up to 12 days resulted in the same deformation mechanism at different sample displacements, with samples failing earlier during tensile testing until a ductile-brittle transition occurred. At 30-40 days water up-take and mass-loss increased significantly and global whitening of samples occurred, while the crystallinity and long period stabilised. Complete degradation had not occurred by the end of the study at 73 days. Through an understanding of how the changes in morphology during degradation affect the micromechanisms of deformation, it may be possible to design microstructures to give a tailored evolution of mechanical response in the body. PMID:15585245

  3. [Degradation of Acid Orange 7 with Persulfate Activated by Silver Loaded Granular Activated Carbon].

    PubMed

    Wang, Zhong-ming; Huang, Tian-yin; Chen, Jia-bin; Li, Wen-wei; Zhang, Li-ming

    2015-11-01

    Granular activated carbon with silver loaded as activator (Ag/GAC) was prepared using impregnation method. N2 adsorption, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) were adopted to characterize the Ag/GAC, showing that silver was successfully loaded on granular activated carbon. The oxidation degradation of acid orange 7 (AO7) by the Ag/GAC activated by persulfate (PS) was investigated at ambient temperature. The influences of factors such as Ag loading, PS or Ag/GAC dosages and initial pH on the degradation of AO7 were evaluated. The results demonstrated that the degradation rate of AO7 could reach more than 95.0% after 180 min when the Ag loading content, PS/AO7 molar ratio, the Ag/GAC dosage were 12.7 mg x g(-1), 120: 1, 1.0 g x L(-1), respectively. The initial pH had significant effect on the AO7 degradation, with pH 5.0 as the optimal pH for the degradation of AO7. The possible degradation pathway was proposed for the AO7 degradation by using UV-visible spectroscopy and gas chromatography-mass spectrometry (GG/MS). The azo bond and naphthalene ring in the AO7 were destroyed during the degradation, with phthalic acid and acetophenone as the main degradation products. PMID:26910999

  4. EVALUATING DEGRADATION RATES OF CHLORINATED ORGANICS IN GROUNDWATER USING ANALYTICAL MODELS

    EPA Science Inventory

    The persistence and fate of organic contaminants in the environment largely depends on their rate of degradation. Most studies of degradation rate are performed in the lab where chemical conditions can be controlled precisely. Unfortunately, literature values for lab degradation ...

  5. Microbial Degradation of Chlorogenic Acid by a Sphingomonas sp. Strain.

    PubMed

    Ma, Yuping; Wang, Xiaoyu; Nie, Xueling; Zhang, Zhan; Yang, Zongcan; Nie, Cong; Tang, Hongzhi

    2016-08-01

    In order to elucidate the metabolism of chlorogenic acid by environmental microbes, a strain of Sphingomonas sp. isolated from tobacco leaves was cultured under various conditions, and chlorogenic acid degradation and its metabolites were investigated. The strain converting chlorogenic acid was newly isolated and identified as a Sphingomonas sp. strain by 16S rRNA sequencing. The optimal conditions for growth and chlorogenic acid degradation were 37 °C and pH 7.0 with supplementation of 1.5 g/l (NH4)2SO4 as the nitrogen source and 2 g/l chlorogenic acid as the sole carbon source. The maximum chlorogenic acid tolerating capability for the strain was 5 g/l. The main metabolites were identified as caffeic acid, shikimic acid, and 3,4-dihydroxybenzoic acid based on gas chromatography-mass spectrometry analysis. The analysis reveals the biotransformation mechanism of chlorogenic acid in microbial cells isolated from the environment. PMID:27068831

  6. Microbial degradation of usnic acid in the reindeer rumen

    NASA Astrophysics Data System (ADS)

    Sundset, Monica A.; Barboza, Perry S.; Green, Thomas K.; Folkow, Lars P.; Blix, Arnoldus Schytte; Mathiesen, Svein D.

    2010-03-01

    Reindeer ( Rangifer tarandus) eat and utilize lichens as an important source of energy and nutrients in winter. Lichens synthesize and accumulate a wide variety of phenolic secondary compounds, such as usnic acid, as a defense against herbivores and to protect against damage by UV-light in solar radiation. We have examined where and to what extent these phenolic compounds are degraded in the digestive tract of the reindeer, with particular focus on usnic acid. Three male reindeer were given ad libitum access to a control diet containing no usnic acid for three weeks and then fed lichens ad libitum (primarily Cladonia stellaris) containing 9.1 mg/g DM usnic acid for 4 weeks. Usnic acid intake in reindeer on the lichen diet was 91-117 mg/kg BM/day. In spite of this, no trace of usnic acid or conjugates of usnic acid was found either in fresh rumen fluid, urine, or feces. This suggests that usnic acid is rapidly degraded by rumen microbes, and that it consequently is not absorbed by the animal. This apparent ability to detoxify lichen phenolic compounds may gain increased importance with future enhanced UV-B radiation expected to cause increased protective usnic acid/phenol production in lichens.

  7. Eigen model with general fitness functions and degradation rates

    NASA Astrophysics Data System (ADS)

    Hu, Chin-Kun; Saakian, David B.

    2006-03-01

    We present an exact solution of Eigen's quasispecies model with a general degradation rate and fitness functions, including a square root decrease of fitness with increasing Hamming distance from the wild type. The found behavior of the model with a degradation rate is analogous to a viral quasi-species under attack by the immune system of the host. Our exact solutions also revise the known results of neutral networks in quasispecies theory. To explain the existence of mutants with large Hamming distances from the wild type, we propose three different modifications of the Eigen model: mutation landscape, multiple adjacent mutations, and frequency-dependent fitness in which the steady state solution shows a multi-center behavior.

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

    PubMed Central

    Tahmourespour, Arezoo; Tabatabaee, Nooroldin; Khalkhali, Hossein; Amini, Imane

    2016-01-01

    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 Pistachio-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. PMID:27092220

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 curre...

  10. FURTHER STUDY OF ADIPIC ACID DEGRADATION IN FGD SCRUBBERS

    EPA Science Inventory

    The report gives results of investigations of adipic acid degradation to account for losses observed during earlier studies where it was used as an additive to improve SO2 scrubber performance. Bench-scale experiments identified the major species resulting from the oxidative degr...

  11. The impact of the various chemical and physical factors on the degradation rate of bronopol.

    PubMed

    Matczuk, M; Obarski, N; Mojski, M

    2012-10-01

    Bronopol (2-bromo-2-nitropropane-1,3-diol) is used as preservative in cosmetic industry. Its main role in commercial products consists in protection of the cosmetic composition stability by inhibiting the development of micro-organisms. Unfortunately, preservatives can also undergo the degradation processes. The aim of examinations was to prove that bronopol decomposes in aqueous solutions and storage conditions have a significance influence on its degradation rate. High-performance liquid chromatography method (methanol/water with hydrochloric acid 5:95 v/v) with spectrophotometric detection (210 nm) was used for examining the decomposition rate of bronopol. The impact of chemical (addition of cosmetics components: citric acid and/or sodium dodecylsulfate) and physical (elevated and ambient temperature, sunlight or ultraviolet radiation and air access) factors has been elaborated. Bronopol decomposes most rapidly (independently on the sample surrounding conditions) when it is in solution with sodium dodecylsulfate, the inverse dependence is observed in the presence of two compounds - citric acid and sodium dodecylsulfate. Additionally, the elevated temperature causes the acceleration of decomposition. Bronopol degradation by-products were also identified as methanol, formic acid, tris(hydroxymethyl)methane and 2-bromo-2-nitroethanol. PMID:22612984

  12. Macro kinetic studies for photocatalytic degradation of benzoic acid in immobilized systems.

    PubMed

    Mehrotra, Kanheya; Yablonsky, Gregory S; Ray, Ajay K

    2005-09-01

    Semiconductor photocatalytic process has been studied extensively in recent years due to its intriguing advantages in environmental remediation. In this study, a two-phase swirl-flow monolithic-type reactor is used to study the kinetics of photocatalytic degradation of benzoic acid in immobilized systems. Transport contributions into the observed degradation rates were determined when catalyst is immobilized. Intrinsic kinetic rate constants and its dependence on light intensity and catalyst layer thickness, values of adsorption equilibrium constant, internal as well as external mass transfer parameters were determined. The simultaneous effect of catalyst loading and light intensity and optimum catalyst layer thickness were also determined experimentally. Reaction rate constants and overall observed degradation rates were compared with slurry systems. PMID:16054912

  13. [Study on cooperating degradation of cypermethrin and 3-phenoxybenzoic acid by two bacteria strains].

    PubMed

    Xu, Yu-Xin; Sun, Ji-Quan; Li, Xiao-Hui; Li, Shun-Peng; Chen, Yi

    2007-10-01

    The microbial cooperated reaction is one of the most important forms of microbial degradation of organic pollutants. Although there were many research reports of cooperating degradation, less report on the microbial cooperated of pyrethroid degradation to be found. We have isolated one degrading-bacteria strain named CDT3 for degradation of cypermethrin, which can degraded the cypermethrin into 3-PBA and DCVA. At the same time, we also isolated another degrading-bacteria strain named as PBM11, which could get multiplication on 3-PBA as its C source and energy source. The cooperative degradation process of cypermethrin and 3-Phenoxybenzoic acid (3-PBA) using the two degrading-bacteria strain CDT3 and PBM11 was investigated. An obvious inhibition to the cypermethrin degrading-bacterium strain CDT3 (Rhodococcus sp.) by its metabolic mediate 3-PBA was found; meanwhile there is no effect on the growth of 3-PBA degrading-bacterium strain PBM11 (Pesudomonas sp.) when the concentration of cypermethrin was lower than 200 mg/L. The degradation rate of cypermethrin by both strain CDT3 and PBM11 was higher than that by CDT3 alone. The biomass of PBM11 increased along with the degradation of cypermethrin and 3-PBA, but that of CDT3 not. There was no the accumulation of 3-PBA when the simultaneous addition of strain CDT3 and PBM11, however, an obvious one within 24h if inoculation of strain PBM11 was later 24h after inoculation of strain CDT3, Subsequently the 3-PBA was degraded rapidly by strain PBM11. The strains CDT3 and PBM11 showed some characteristics of co-metabolism, however it is not actual degradation form of co-metabolism. For examples, although the degrading sub product of cypermethrin by CDT3 could be utilized, the multiplication of PBM11 could not enhance the multiplication of CDT3, implied there is no obvious relationship between the two strains. Also, to add PBM11 could eliminate the inhibition of 3-PBA to CDT3. Thus, the cooperating degradation of strains CDT3

  14. Degradation of CYANEX 301 in Contact with Nitric Acid Media

    SciTech Connect

    Philippe Marc; Radu Custelcean; Gary S. Groenewold; John R. Klaehn; Dean R. Peterman; Laetitia H. Delmau

    2012-10-01

    The nature of the degradation product obtained upon contacting CYANEX 301 (bis(2,4,4-trimethylpentyl)dithiophosphinic acid) with nitric acid has been elucidated and found to be a disulfide derivative. The first step to the degradation of CYANEX 301 in toluene has been studied using 31P{1H} NMR after being contacted with nitric acid media. The spectrum of the degradation product exhibits a complex multiplet around dP = 80 ppm. A succession of purifications of CYANEX 301 has resulted in single crystals of the acidic form and the corresponding ammonium salt. Unlike the original CYANEX 301, which consists of a complex diastereomeric mixture displaying all possible combinations of chiral orientations at the 2-methyl positions, the purified crystals were shown by single-crystal X-ray diffraction to be racemates, containing 50:50 mixtures of the [R;R] and [S;S] diastereomers. The comparison between the 31P {1H} NMR spectra of the degradation products resulting from the diastereomerically pure CYANEX 301 and the original diastereomeric mixture has elucidated the influence of the isomeric composition on the multiplicity of the 31P {1H} NMR peak. These NMR data indicate the initial degradation leads to a disulfide-bridged condensation product displaying multiple resonances due to phosphorus–phosphorus coupling, which is caused by the inequivalence of the two P atoms as a result of their different chirality. A total of nine different NMR resonances, six of which display phosphorus–phosphorus coupling, could be assigned, and the identity of the peaks corresponding to phosphorus atoms coupled to each other was confirmed by 31P {1H} homodecoupled NMR analysis.

  15. Influence of Root Exudates on the Bacterial Degradation of Chlorobenzoic Acids

    PubMed Central

    Lovecká, Petra; Dražková, Milena; Macková, Martina; Macek, Tomas

    2013-01-01

    Degradation of chlorobenzoic acids (e.g., products of microbial degradation of PCB) by strains of microorganisms isolated from PCB contaminated soils was assessed. From seven bulk-soil isolates two strains unique in ability to degrade a wider range of chlorobenzoic acids than others were selected, individually and even in a complex mixture of 11 different chlorobenzoic acids. Such a feature is lacking in most tested degraders. To investigate the influence of vegetation on chlorobenzoic acids degraders, root exudates of two plant species known for supporting PCB degradation in soil were tested. While with individual chlorobenzoic acids the presence of plant exudates leads to a decrease of degradation yield, in case of a mixture of chlorobenzoic acids either a change in bacterial degradation specificity, associated with 3- and 4-chlorobenzoic acid, or an extension of the spectrum of degraded chlorobenzoic acids was observed. PMID:24222753

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

    PubMed

    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

  17. Energetics and kinetics of anaerobic aromatic and fatty acid degradation. Progress report, March 1992--June 1995

    SciTech Connect

    McInerney M.J.

    1995-06-23

    Factors affecting the rate and extent of benzoate degradation by anaerobic syntrophic consortia were studied. Cocultures of a syntrophic benzoate degrader, strain SB, with a hydrogen/formate-using sulfate reducer degraded benzoate to a threshold that depended on the amount of substrate and acetate present. The benzoate threshold was not a function of the inhibition of benzoate degradation capacity by acetate or the toxicity of the undissociated form of acetate. Rather, a critical or minimal Gibb`s free energy value may exist where thermodynamic constraints preclude further benzoate degradation. A sensitive assay to detect low formate concentrations was developed to measure the formate levels when the benzoate threshold was reached. We showed that increased acetate concentrations, even when hydrogen and formate levels are low, affects the extent of benzoate degradation, implicating the importance of interspecies acetate transfer. In addition to benzoate, various saturated and unsaturated fatty acids, 2-methylbutyrate, and methyl esters of fatty acids supported growth in coculture with a hydrogen-using partner. SB is the only syntrophic bacterium known to use both benzoate and fatty acids. Phylogenetic analysis showed that SB clustered with sulfate reducers in the delta subclass of the Proteobacteria. SB grew well in coculture with Desulfoarculus baarsii, a sulfate reducer that uses formate but not hydrogen. This unequivocally shows that SB can grow by interspecies formate transfer.

  18. Poly(lactic acid) degradable plastics, coatings, and binders

    SciTech Connect

    Bonsignore, P.V.; Coleman, R.D.; Mudde, J.P.

    1992-05-01

    Biochemical processes to derive value from the management of high carbohydrate food wastes, such as potato starch, corn starch, and cheese whey permeate, have typically been limited to the production of either ethanol or methane. Argonne National Laboratory (ANL) believes that lactic acid presents an attractive option for an alternate fermentation end product, especially in light of lactic acids` being a viable candidate for conversion to environmentally safe poly(lactic acid) (PLA) degradable plastics, coatings, and binders. Technology is being developed at ANL to permit a more cost effective route to modified high molecular weight PLA. Preliminary data on the degradation behavior of these modified PLAs shows the retention to the inherent hydrolytic degradability of the PLA modified, however, by introduced compositional variables. A limited study was done on the hydrolytic stability of soluble oligomers of poly(L-lactic acid). Over a 34 day hold period, water-methanol solutions of Pl-LA oligomers in the 2-10 DP range retained some 75% of their original molecular weight.

  19. Poly(lactic acid) degradable plastics, coatings, and binders

    SciTech Connect

    Bonsignore, P.V.; Coleman, R.D.; Mudde, J.P.

    1992-01-01

    Biochemical processes to derive value from the management of high carbohydrate food wastes, such as potato starch, corn starch, and cheese whey permeate, have typically been limited to the production of either ethanol or methane. Argonne National Laboratory (ANL) believes that lactic acid presents an attractive option for an alternate fermentation end product, especially in light of lactic acids' being a viable candidate for conversion to environmentally safe poly(lactic acid) (PLA) degradable plastics, coatings, and binders. Technology is being developed at ANL to permit a more cost effective route to modified high molecular weight PLA. Preliminary data on the degradation behavior of these modified PLAs shows the retention to the inherent hydrolytic degradability of the PLA modified, however, by introduced compositional variables. A limited study was done on the hydrolytic stability of soluble oligomers of poly(L-lactic acid). Over a 34 day hold period, water-methanol solutions of Pl-LA oligomers in the 2-10 DP range retained some 75% of their original molecular weight.

  20. First-order kinetics analysis of monomer composition dependent polyhydroxyalkanoic acid degradation in Pseudomonas spp.

    PubMed

    Choi, Mun Hwan; Rho, Jong Kook; Lee, Ho-Joo; Song, Jae Jun; Yoon, Sung Chul; Lee, Sang Yeol

    2003-01-01

    The intracellular degradation of polyhydroxyalkanoic acid (PHA) in pseudomonads was investigated by first-order kinetics analysis using the initial rate method. One type of PHA was accumulated in five Pseudomonas spp., P. oleovorans, P. aeruginosa, P. fluorescens, P. citronellolis, and P. putida, by growing them on octanoic acid. The monomer compositions of the five PHA were not significantly different from one another: 85-90 mol % 3-hydroxyoctanoic acid (3HO), 7-12 mol % 3-hydorxycaproic acid (3HC), and 3-6 mol % 3-hydroxydecanoic acid (3HD). The first-order degradation rate constants (k(1)) for the octanoate-derived PHA (designated P(3HO)) in the five species were in a similar range between 0.060 and 0.088 h(-1). This may indicate the similar specificities of the five intracellular depolymerases. In addition, the similar k(1) among the different species may correlate with the high degree of amino acid sequence identities (over 85%) among the intracellular PHA depolymerase phaZ genes. Six other chemically different types of PHA were accumulated in P. putida from n-nonanoic acid, n-decanoic acid, 5-phenyvaleric acid, or 11-phenoxyundecanoic acid as a single or a mixed carbon source. The calculated k(1) values were characteristic to each PHA, reflecting their chemical structures. In comparison with P(3HO), an increase in the levels of the two minor monomers 3HC and 3HD as in P(21 mol % 3HC-co-56 mol % 3HO-co-23 mol % 3HD) significantly slowed the rate of intracellular degradation. From the comparison of k(1) values, it is suggested that the P. putida intracellular depolymerase is most active against P(3HO). PMID:12625741

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

    PubMed

    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

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

    PubMed

    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

  3. Amino Acid Degradations Produced by Lipid Oxidation Products.

    PubMed

    Hidalgo, Francisco J; Zamora, Rosario

    2016-06-10

    Differently to amino acid degradations produced by carbohydrate-derived reactive carbonyls, amino acid degradations produced by lipid oxidation products are lesser known in spite of being lipid oxidation a major source of reactive carbonyls in food. This article analyzes the conversion of amino acids into Strecker aldehydes, α-keto acids, and amines produced by lipid-derived free radicals and carbonyl compounds, as well as the role of lipid oxidation products on the reactions suffered by these compounds: the formation of Strecker aldehydes and other aldehydes from α-keto acids; the formation of Strecker aldehydes and olefins from amines; the formation of shorter aldehydes from Strecker aldehydes; and the addition reactions suffered by the olefins produced from the amines. The relationships among all these reactions and the effect of reaction conditions on them are discussed. This knowledge should contribute to better control food processing in order to favor the formation of desirable beneficial compounds and to inhibit the production of compounds with deleterious properties. PMID:25748518

  4. Study on degradation kinetics of 2-(2-hydroxypropanamido) benzoic acid in aqueous solutions and identification of its major degradation product by UHPLC/TOF-MS/MS.

    PubMed

    Zhang, Qili; Guan, Jiao; Rong, Rong; Zhao, Yunli; Yu, Zhiguo

    2015-08-10

    A RP-HPLC method was developed and validated for the degradation kinetic study of 2-(2-hydroxypropanamido) benzoic acid (HPABA), a promising anti-inflammatory drug, which would provide a basis for further studies on HPABA. The effects of pH, temperature, buffer concentration and ionic strength on the degradation kinetics of HPABA were discussed. Experimental parameters such as degradation rate constants (k), activation energy (Ea), acid and alkali catalytic constants (k(ac), k(al)), shelf life (t1/2) and temperature coefficient (Q10) were calculated. The results indicated that degradation kinetics of HPABA followed zero-order reaction kinetics; degradation rate constants (k) of HPABA at different pH values demonstrated that HPABA was more stable in neutral and near-neutral conditions; the function of temperature on k obeyed the Arrhenius equation (r = 0.9933) and HPABA was more stable at lower temperature; with the increase of ionic strength and buffer concentration, the stability of HPABA was decreased. The major unknown degradation product of HPABA was identified by UHPLC/TOF-MS/MS with positive electrospray ionization. Results demonstrated that the hydrolysis product was the primary degradation product of HPABA and it was deduced as anthranilic acid. PMID:25935790

  5. Data Filtering Impact on PV Degradation Rates and Uncertainty (Poster)

    SciTech Connect

    Jordan, D. C.; Kurtz, S. R.

    2012-03-01

    To sustain the commercial success of photovoltaics (PV) it becomes vital to know how power output decreases with time. In order to predict power delivery, degradation rates must be determined accurately. Data filtering, any data treatment assessment of long-term field behavior, is discussed as part of a more comprehensive uncertainty analysis and can be one of the greatest sources of uncertainty in long-term performance studies. Several distinct filtering methods such as outlier removal and inclusion of only sunny days on several different metrics such as PVUSA, performance ratio, DC power to plane-of-array irradiance ratio, uncorrected, and temperature-corrected were examined. PVUSA showed the highest sensitivity while temperature-corrected power over irradiance ratio was found to be the least sensitive to data filtering conditions. Using this ratio it is demonstrated that quantification of degradation rates with a statistical accuracy of +/- 0.2%/year within 4 years of field data is possible on two crystalline silicon and two thin-film systems.

  6. Protocatechuic Acid Promoted Alachlor Degradation in Fe(III)/H2O2 Fenton System.

    PubMed

    Qin, Yaxin; Song, Fahui; Ai, Zhihui; Zhang, Pingping; Zhang, Lizhi

    2015-07-01

    In this study, we demonstrate that protocatechuic acid (PCA) can significantly promote the alachlor degradation in the Fe(III)/H2O2 Fenton oxidation system. It was found that the addition of protocatechuic acid could increase the alachlor degradation rate by 10 000 times in this Fenton oxidation system at pH = 3.6. This dramatic enhancement of alachlor degradation was attributed to the complexing and reduction abilities of protocatechuic ligand, which could form stable complexes with ferric ions to prevent their precipitation and also accelerate the Fe(III)/Fe(II) cycle to enhance the ·OH generation. Meanwhile, the Fe(III)/PCA/H2O2 system could also work well at near natural pH even in the case of PCA concentration as low as 0.1 mmol/L. More importantly, both alachlor and PCA could be effectively mineralized in this Fenton system, suggesting the environmental benignity of PCA/Fe(III)/H2O2 Fenton system. We employed gas chromatography-mass spectrometry to identify the degradation intermediates of alachlor and then proposed a possible alachlor degradation mechanism in this novel Fenton oxidation system. This study provides an efficient way to remove chloroacetanilide herbicides, and also shed new insight into the possible roles of widely existed phenolic acids in the conversion and the mineralization of organic contaminants in natural aquatic environment. PMID:26066010

  7. Nitrogen incorporation into lignite humic acids during microbial degradation

    SciTech Connect

    Dong, L.H.; Yuan, H.L.

    2009-07-01

    Previous study showed that nitrogen content in lignite humic acids (HA) increased significantly during lignite biodegradation. In this paper we evaluated the factors responsible for the increased level of N in HA and the formation of new nitrogen compound following microbial degradation. When the ammonium sulfate concentration in lignite medium was 0.5%, the N-content in HA was higher than that in the crude lignite humic acid (cHA); when the ammonium sulfate concentration was epsilon 0.5%, both the biodegraded humic acid (bHA) N-content and the content of bHA in lignite increased significantly, but at 2.0% no increase was observed. This indicated that HA incorporated N existing in the lignite medium, and more HA can incorporate more N with the increase of bHA amount in lignite during microbial degradation. CP/MAS {sup 15}N NMR analysis showed that the N incorporated into HA during biotransformation was in the form of free or ionized NH{sub 2}-groups in amino acids and sugars, as well as NH{sub 4}{sup +}. We propose nitrogen can be incorporated into HA biotically and abiotically. The high N content bHA has a potential application in agriculture since N is essential for plant growth.

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

    PubMed

    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. DNA Profiling Success Rates from Degraded Skeletal Remains in Guatemala.

    PubMed

    Johnston, Emma; Stephenson, Mishel

    2016-07-01

    No data are available regarding the success of DNA Short Tandem Repeat (STR) profiling from degraded skeletal remains in Guatemala. Therefore, DNA profiling success rates relating to 2595 skeletons from eleven cases at the Forensic Anthropology Foundation of Guatemala (FAFG) are presented. The typical postmortem interval was 30 years. DNA was extracted from bone powder and amplified using Identifiler and Minifler. DNA profiling success rates differed between cases, ranging from 50.8% to 7.0%, the overall success rate for samples was 36.3%. The best DNA profiling success rates were obtained from femur (36.2%) and tooth (33.7%) samples. DNA profiles were significantly better from lower body bones than upper body bones (p = <0.0001). Bone samples from males gave significantly better profiles than samples from females (p = <0.0001). These results are believed to be related to bone density. The findings are important for designing forensic DNA sampling strategies in future victim recovery investigations. PMID:27364268

  10. Degradation of 3-chloro-4-hydroxybenzoic acid in biological treated effluent by gamma irradiation

    NASA Astrophysics Data System (ADS)

    Chu, Libing; Wang, Jianlong

    2016-02-01

    Gamma irradiation-induced degradation of a chlorinated aromatic compound, 3-chloro-4-hydroxybenzoic acid (CHBA) in biological treated effluent was studied and the results were compared with those obtained in deionized water. Gamma irradiation led to a complete decomposition of CHBA and a partial mineralization in the treated effluent. The removal of CHBA followed the pseudo first-order reaction kinetic model and the rate constant in the treated effluent was 1.7-3.5 times lower than that in deionized water. The CHBA degradation rate was higher at acidic condition than at neutral and alkaline conditions. The radiolytic yield, G-value for CHBA degradation was lower in the treated effluent, which decreased with increase in absorbed doses and increased with increase in initial concentrations of CHBA. The degradation mechanism of CHBA using gamma irradiation was proposed through the oxidation by -OH and reduction by eaq- and H- radicals. As exposed to gamma irradiation, dechlorination takes place rapidly and combines with the oxidation and cleavage of the aromatic ring, producing chloride ions, small carboxylic acids, acetaldehyde and other intermediates into the solution.

  11. 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

    NASA Astrophysics Data System (ADS)

    Campos, Sandro X.; Vieira, Eny M.; Cordeiro, Paulo J. M.; Rodrigues-Fo, Edson; Murgu, Michael

    2003-12-01

    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 1.13×10 -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.

  12. Study of kinetics of degradation of cyclohexane carboxylic acid by acclimated activated sludge.

    PubMed

    Wang, Chunhua; Shi, Shuian; Chen, Hongyan

    2016-01-01

    Activated sludge contains complex microorganisms, which are highly effective biodegrading agents. In this study, the kinetics of biodegradation of cyclohexane carboxylic acid (CHCA) by an acclimated aerobic activated sludge were investigated. The results showed that after 180 days of acclimation, the activated sludge could steadily degrade >90% of the CHCA in 120 h. The degradation of CHCA by the acclimated activated sludge could be modeled using a first-order kinetics equation. The equations for the degradation kinetics for different initial CHCA concentrations were also obtained. The kinetics constant, kd, decreased with an increase in the CHCA concentration, indicating that, at high concentrations, CHCA had an inhibiting effect on the microorganisms in the activated sludge. The effects of pH on the degradation kinetics of CHCA were also investigated. The results showed that a pH of 10 afforded the highest degradation rate, indicating that basic conditions significantly promoted the degradation of CHCA. Moreover, it was found that the degradation efficiency for CHCA increased with an increase in temperature and concentration of dissolved oxygen under the experimental conditions. PMID:27191578

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

    PubMed

    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

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

    PubMed

    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

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

    SciTech Connect

    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.

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

    SciTech Connect

    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.

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

    NASA Astrophysics Data System (ADS)

    Guo, Wenlu; Liu, Xiaolin; Huo, Pengwei; Gao, Xun; Wu, Di; Lu, Ziyang; Yan, Yongsheng

    2012-07-01

    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).

  18. Effects of environmental conditions on aerobic degradation of a commercial naphthenic acid.

    PubMed

    Kinley, Ciera M; Gaspari, Daniel P; McQueen, Andrew D; Rodgers, John H; Castle, James W; Friesen, Vanessa; Haakensen, Monique

    2016-10-01

    Naphthenic acids (NAs) are problematic constituents in energy-derived waters, and aerobic degradation may provide a strategy for mitigating risks to aquatic organisms. The overall objective of this study was to determine the influence of concentrations of N (as ammonia) and P (as phosphate), and DO, as well as pH and temperatures on degradation of a commercial NA in bench-scale reactors. Commercial NAs provided replicable compounds necessary to compare influences of environmental conditions on degradation. NAs were quantified using high performance liquid chromatography. Microbial diversity and relative abundance were measured in treatments as explanatory parameters for potential effects of environmental conditions on microbial populations to support analytically measured NA degradation. Environmental conditions that positively influenced degradation rates of Fluka NAs included nutrients (C:N 10:1-500:1, C:P 100:1-5000:1), DO (4.76-8.43 mg L(-1)), pH (6-8), and temperature (5-25 °C). Approximately 50% removal of 61 ± 8 mg L(-1) was achieved in less than 2 d after NA introduction, achieving the method detection limit (5 mg L(-1)) by day 6 of the experiment in treatments with a C:N:P ratio of 100:10:1, DO > 8 mg L(-1), pH ∼8-9, and temperatures >23 °C. Microbial diversity was lowest in lower temperature treatments (6-16 °C), which may have resulted in observed slower NA degradation. Based on results from this study, when macro- and micronutrients were available, DO, pH, and temperature (within environmentally relevant ranges) influenced rates of aerobic degradation of Fluka NAs. This study could serve as a model for systematically evaluating environmental factors that influence NA degradation in field scenarios. PMID:27459161

  19. Microbial degradation of isosaccharinic acid at high pH

    PubMed Central

    Bassil, Naji M; Bryan, Nicholas; Lloyd, Jonathan R

    2015-01-01

    Intermediate-level radioactive waste (ILW), which dominates the radioactive waste inventory in the United Kingdom on a volumetric basis, is proposed to be disposed of via a multibarrier deep geological disposal facility (GDF). ILW is a heterogeneous wasteform that contains substantial amounts of cellulosic material encased in concrete. Upon resaturation of the facility with groundwater, alkali conditions will dominate and will lead to the chemical degradation of cellulose, producing a substantial amount of organic co-contaminants, particularly isosaccharinic acid (ISA). ISA can form soluble complexes with radionuclides, thereby mobilising them and posing a potential threat to the surrounding environment or ‘far field'. Alkaliphilic microorganisms sampled from a legacy lime working site, which is an analogue for an ILW-GDF, were able to degrade ISA and couple this degradation to the reduction of electron acceptors that will dominate as the GDF progresses from an aerobic ‘open phase' through nitrate- and Fe(III)-reducing conditions post closure. Furthermore, pyrosequencing analyses showed that bacterial diversity declined as the reduction potential of the electron acceptor decreased and that more specialised organisms dominated under anaerobic conditions. These results imply that the microbial attenuation of ISA and comparable organic complexants, initially present or formed in situ, may play a role in reducing the mobility of radionuclides from an ILW-GDF, facilitating the reduction of undue pessimism in the long-term performance assessment of such facilities. PMID:25062127

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

    PubMed

    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

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

    NASA Astrophysics Data System (ADS)

    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)

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

    PubMed

    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

  3. Effect of Particle Addition on Degradation Rate of Methylene Blue in an Ultrasonic Field

    NASA Astrophysics Data System (ADS)

    Honma, Chiemi; Kobayashi, Daisuke; Matsumoto, Hideyuki; Takahashi, Tomoki; Kuroda, Chiaki; Otake, Katsuto; Shono, Atsushi

    2013-07-01

    Ultrasound has been found to be an attractive advanced technology for the degradation of hazardous organic compounds in water. In addition, the sonochemical reaction is enhanced by particle addition. However, the enhancement mechanism of particle addition has not been investigated well, because ultrasound enhances not only chemical reactions but also mass transfer. In this study, the ultrasonic degradation of methylene blue was carried out, and the effects of the ultrasonic irradiation condition on the degradation rate were investigated. The effect of ultrasonic frequency on the improvement of degradation by particle addition was also investigated. The order of degradation rate with frequency was the same as the tendency of sonochemical efficiency value obtained using KI oxidation dosimetry method (SEKI). The degradation process of methylene blue was intensified by particle addition, and the degradation rate increased with increasing amount of particle addition. The enhancement of degradation rate by particle addition was influenced by both ultrasonic frequency and type or diameter of particles.

  4. Effect of the Electric Field Frequency on Ascorbic Acid Degradation during Thermal Treatment by Ohmic Heating

    PubMed Central

    Mercali, Giovana Domeneghini; Schwartz, Steven; Marczak, Ligia Damasceno Ferreira; Tessaro, Isabel Cristina; Sastry, Sudhir

    2014-01-01

    In this work, the influence of the electric field frequency and solids content on the degradation kinetics of ascorbic acid during ohmic heating of acerola pulp and acerola serum was investigated. The degradation percentage of ascorbic acid in the pulp after 120 min of heating varied between 12 and 17%. For the serum, the degradation percentage was in the range of 13 and 18%. The results were fitted to the first-order model, and the kinetic rate constants ranged from 1.1 to 1.6 × 10−3 min−1 and from 1.1 to 1.5 × 10−3 min−1 for pulp and serum, respectively. D values ranged between 1480 and 2145 min for the pulp and between 1524 and 1951 min for the serum. A distinct behavior between the kinetic parameters of the pulp and serum in electric field frequencies ranging from 10 to 1000 Hz indicates that the presence of distinct amounts and types of solids might affect the rate of the electron transfer in electrochemical reactions. These variables may also affect the polarization process stimulated by the oscillating electric field. The non-achievement of the equilibrium of the polarization process may have an influence on oxidation reactions, affecting the predisposition to hydrogen donation from the ascorbic acid molecule. PMID:24892902

  5. Effect of the electric field frequency on ascorbic acid degradation during thermal treatment by ohmic heating.

    PubMed

    Mercali, Giovana Domeneghini; Schwartz, Steven; Marczak, Ligia Damasceno Ferreira; Tessaro, Isabel Cristina; Sastry, Sudhir

    2014-06-25

    In this work, the influence of the electric field frequency and solids content on the degradation kinetics of ascorbic acid during ohmic heating of acerola pulp and acerola serum was investigated. The degradation percentage of ascorbic acid in the pulp after 120 min of heating varied between 12 and 17%. For the serum, the degradation percentage was in the range of 13 and 18%. The results were fitted to the first-order model, and the kinetic rate constants ranged from 1.1 to 1.6×10(-3) min(-1) and from 1.1 to 1.5×10(-3) min(-1) for pulp and serum, respectively. D values ranged between 1480 and 2145 min for the pulp and between 1524 and 1951 min for the serum. A distinct behavior between the kinetic parameters of the pulp and serum in electric field frequencies ranging from 10 to 1000 Hz indicates that the presence of distinct amounts and types of solids might affect the rate of the electron transfer in electrochemical reactions. These variables may also affect the polarization process stimulated by the oscillating electric field. The non-achievement of the equilibrium of the polarization process may have an influence on oxidation reactions, affecting the predisposition to hydrogen donation from the ascorbic acid molecule. PMID:24892902

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

    PubMed

    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

  7. Production and Degradation of Oxalic Acid by Brown Rot Fungi

    PubMed Central

    Espejo, Eduardo; Agosin, Eduardo

    1991-01-01

    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. PMID:16348522

  8. Degradation Kinetics and Mechanism of a β-Lactam Antibiotic Intermediate, 6-Aminopenicillanic Acid, in a New Integrated Production Process.

    PubMed

    Su, Min; Sun, Hua; Zhao, Yingying; Lu, Aidang; Cao, Xiaohui; Wang, Jingkang

    2016-01-01

    In an effort to promote sustainability and to reduce manufacturing costs, the traditional production process for 6-aminopenicillanic acid (6-APA) has been modified to include less processing units. The objectives of this study are to investigate the degradation kinetics of 6-APA, to propose a reasonable degradation mechanism, and to optimize the manufacturing conditions within this new process. A series of degradation kinetic studies were conducted in the presence of impurities, as well as at various chemical and physical conditions. The concentrations of 6-APA were determined by high-performance liquid chromatography. An Arrhenius-type kinetic model was established to give a more accurate prediction on the degradation rates of 6-APA. A hydrolysis degradation mechanism is shown to be the major pathway for 6-APA. The degradation mechanisms and the kinetic models for 6-APA in the new system enable the design of a good manufacturing process with optimized parameters. PMID:26852849

  9. Energetics and kinetics of anaerobic aromatic and fatty acid degradation

    SciTech Connect

    McInerney, M.J.

    1992-11-16

    The kinetics of benzoate degradation by the anaerobic syntrophic bacterium, Syntrophus buswellii, was studied in coculture with Desulfovibrio strain G11. The threshold value for benzoate degradation was dependent on the acetate concentration with benzoate threshold values ranging from 2.4 [mu]M at 20 mM acetate to 30.0 [mu]M at 65 mM acetate. Increasing acetate concentrations also inhibited the rate of benzoate degradation with a apparent K[sub i] for acetate inhibition of 7.0 mM. Lower threshold values were obtained when nitrate rather than sulfate was the terminal electron acceptor. These data are consistent with a thermodynamic explanation for the threshold, and suggest that there is a minimum Gibbs free energy value required for the degradation of benzoate. An acetoacetyl-CoA thiolase has been isolated from Syntrophomonas wolfei; it is apparently a key enzyme controlling the synthesis of poly-B-hydroxyalkanoate from acetyl-CoA in this organism. Kinetic characterization of the acetoacetyl-CoA thiolase from S. wolfei showed that it is similar in its structural, kinetic, and apparent regulatory properties to other biosynthetic acetoacetyl-CoA thiolases from phylogenetically distinct bacteria that synthesize PHA. Intracellular concentrations of CoA and acetyl-CoA are believed to be critical factors regulating the activity of the acetoacetyl-CoA thiolase in S. wolfei. We have also isolated and characterized several new halophilic anaerobic fermentative anaerobes. Phylogenetic analysis indicates that one of these bacteria is a new species in the genus, Haloanaerobium. Two other species appear to be members of the genus, Halobacteroides. Several halophilic acetoclastic methanogenic bacteria have also been isolated and their physiological properties are currently under investigation. We have also isolated an acetate-using dissimilatory iron-reducing bacterium.

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

    PubMed

    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

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  12. Photolytic and photocatalytic degradation of tetracycline: Effect of humic acid on degradation kinetics and mechanisms.

    PubMed

    Li, Si; Hu, Jiangyong

    2016-11-15

    The widespread occurrence of tetracycline (TC) in the aquatic environment poses a potential risk to aquatic ecosystem and human health. In this study, elimination of TC by photolysis and TiO2 photocatalysis were investigated by using mercury-free UVA-LED as an alternative light source. Particular emphasis was given to the effect of humic acid (HA) on the reaction kinetics and mechanisms of TC removal. Photolytic degradation of TC was slightly enhanced by HA due to its photosensitization effect, as evidenced by the increased steady-state concentrations of OH. The most abundant transformation product of TC, which was formed by the attack of OH radical, was enhanced during photolytic degradation. During photocatalytic experiments, HA dramatically inhibited TC loss due to the surface deactivation of TiO2 and OH quenching. The steady-state concentration of OH was dramatically decreased in the presence of HA. Identification of transformation products showed that HA could inhibit the oxidation pathways initiated by OH during photocatalysis of TC. These findings provide further insights into the assessment of photolysis and photocatalysis for antibiotics elimination in natural waters where HA exists ubiquitously. PMID:27420385

  13. Identification of an itaconic acid degrading pathway in itaconic acid producing Aspergillus terreus.

    PubMed

    Chen, Mei; Huang, Xuenian; Zhong, Chengwei; Li, Jianjun; Lu, Xuefeng

    2016-09-01

    Itaconic acid, one of the most promising and flexible bio-based chemicals, is mainly produced by Aspergillus terreus. Previous studies to improve itaconic acid production in A. terreus through metabolic engineering were mainly focused on its biosynthesis pathway, while the itaconic acid-degrading pathway has largely been ignored. In this study, we used transcriptomic, proteomic, bioinformatic, and in vitro enzymatic analyses to identify three key enzymes, itaconyl-CoA transferase (IctA), itaconyl-CoA hydratase (IchA), and citramalyl-CoA lyase (CclA), that are involved in the catabolic pathway of itaconic acid in A. terreus. In the itaconic acid catabolic pathway in A. terreus, itaconic acid is first converted by IctA into itaconyl-CoA with succinyl-CoA as the CoA donor, and then itaconyl-CoA is hydrated into citramalyl-CoA by IchA. Finally, citramalyl-CoA is cleaved into acetyl-CoA and pyruvate by CclA. Moreover, IctA can also catalyze the reaction between citramalyl-CoA and succinate to generate succinyl-CoA and citramalate. These results, for the first time, identify the three key enzymes, IctA, IchA, and CclA, involved in the itaconic acid degrading pathway in itaconic acid producing A. terreus. The results will facilitate the improvement of itaconic acid production by metabolically engineering the catabolic pathway of itaconic acid in A. terreus. PMID:27102125

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

    PubMed

    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

  15. Effects of material thickness and processing method on poly(lactic-co-glycolic acid) degradation and mechanical performance.

    PubMed

    Shirazi, Reyhaneh Neghabat; Aldabbagh, Fawaz; Ronan, William; Erxleben, Andrea; Rochev, Yury; McHugh, Peter

    2016-10-01

    In this study, the effects of material thickness and processing method on the degradation rate and the changes in the mechanical properties of poly(lactic-co-glycolic acid) material during simulated physiological degradation were investigated. Two types of poly(lactic-co-glycolic acid) materials were considered: 0.12 mm solvent-cast films and 1 mm compression-moulded plates. The experimental results presented in this study were compared to the experimental results of Shirazi et al. (Acta Biomaterialia 10(11):4695-703, 2014) for 0.25 mm solvent-cast films. These experimental observations were used to validate the computational modelling predictions of Shirazi et al. (J Mech Behav Biomed Mater 54: 48-59, 2016) on critical diffusion length scale and also to refine the model parameters. The specific material processing methods considered here did not have a significant effect on the degradation rate and the changes in mechanical properties during degradation; however, they influenced the initial molecular weight and they determined the stiffness and hardness of the poly(lactic-co-glycolic acid) material. The experimental observations strongly supported the computational modelling predictions that showed no significant difference in the degradation rate and the changes in the elastic modulus of poly(lactic-co-glycolic acid) films for thicknesses larger than 100 μm. PMID:27590824

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

    NASA Astrophysics Data System (ADS)

    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.

  17. Degradation of a model pollutant ferulic acid by the endophytic fungus Phomopsis liquidambari.

    PubMed

    Xie, Xing-Guang; Dai, Chuan-Chao

    2015-03-01

    Biodegradation of ferulic acid, by an endophytic fungus called Phomopsis liquidambari was investigated in this study. This strain can use ferulic acid as the sole carbon for growth. Both in mineral salt medium and in soil, more than 97% of added ferulic acid was degraded within 48 h. The metabolites were identified and quantified using GC-MS and HPLC-MS. Ferulic acid was first decarboxylated to 4-vinyl guaiacol and then oxidized to vanillin and vanillic acid, followed by demethylation to protocatechuic acid, which was further degraded through the β-ketoadipate pathway. During degradation, ferulic acid decarboxylase, laccase and protocatechuate 3,4-dioxygenase activities and their gene transcription levels were significantly affected by the variation of substrate and product concentrations. Moreover, ferulic acid degradation was determined to some extent by P. liquidambari laccase. This study is the first report of an endophytic fungus that has a great potential for practical application in ferulic acid-contaminated environments. PMID:25514400

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

    PubMed

    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

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

    PubMed

    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 (p<0.05), followed by Fuji II LC. Valiant-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

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

    PubMed

    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

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

    PubMed

    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

  2. Degradation and enantiomeric fractionation of mecoprop in soil previously exposed to phenoxy acid herbicides - New insights for bioremediation.

    PubMed

    Frková, Zuzana; Johansen, Anders; de Jonge, Lis Wollesen; Olsen, Preben; Gosewinkel, Ulrich; Bester, Kai

    2016-11-01

    Phenoxy acid-contaminated subsoils are common as a result of irregular disposal of residues and production wastes in the past. For enhancing in situ biodegradation at reducing conditions, biostimulation may be an effective option. Some phenoxy acids were marketed in racemic mixtures, and biodegradation rates may differ between enantiomers. Therefore, enantio-preferred degradation of mecoprop (MCPP) in soil was measured to get in-depth information on whether amendment with glucose (BOD equivalents as substrate for microbial growth) and nitrate (redox equivalents for oxidation) can stimulate bioremediation. The degradation processes were studied in soil sampled at different depths (3, 4.5 and 6m) at a Danish urban site with a history of phenoxy acid contamination. We observed preferential degradation of the R-enantiomer only under aerobic conditions in the soil samples from 3- and 6-m depth at environmentally relevant (nM) MCPP concentrations: enantiomer fraction (EF)<0.5. On the other hand, we observed preferential degradation of the S-enantiomer in all samples and treatments at elevated (μM) MCPP concentrations: EF>0.5. Three different microbial communities were discriminated by enantioselective degradation of MCPP: 1) aerobic microorganisms with little enantioselectivity, 2) aerobic microorganisms with R-selectivity and 3) anaerobic denitrifying organisms with S-selectivity. Glucose-amendment did not enhance MCPP degradation, while nitrate amendment enhanced the degradation of high concentrations of the herbicide. PMID:27432728

  3. Enhancement of carboxylic acid degradation with sulfate radical generated by persulfate activation.

    PubMed

    Criquet, J; Nebout, P; Karpel Vel Leitner, N

    2010-01-01

    The aim of this work was to investigate the generation of sulfate radical for the removal of two carboxylic acids in aqueous solution: acetic and citric acids. From photochemical and radiolytic processes, kinetics of the degradation of these two carboxylic acids was studied as a function of the pH of the solution. It was shown that the maximum of acetic acid degradation occurred at pH 5. Above this pH, competitive reactions with the carbon mineralized inhibit the reaction of with the solute. In the case of citric acid, pH has only a little effect on the kinetic of citric acid degradation. The determination of mineralization yields shows several differences depending on carboxylic acids and pH. The degradation of both carboxylic acids was also studied in the radiolysis process whether with or without persulfate addition. A comparison of the processes of sulfate radical production is presented. PMID:20220244

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

    PubMed

    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

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

    NASA Astrophysics Data System (ADS)

    Yun, Hyejeong; Lim, Sangyong; Jo, Cheorun; Chung, Jinwoo; Kim, Soohyun; Kwon, Joong-Ho; Kim, Dongho

    2008-06-01

    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.

  6. Characterization of 2,4-dichlorophenoxyacetic acid and 2,4,5-trichlorophenoxyacetic acid-degrading fungi in Vietnamese soils.

    PubMed

    Itoh, Kazuhito; Kinoshita, Masahiro; Morishita, Shigeyuki; Chida, Masateru; Suyama, Kousuke

    2013-04-01

    Sixty-nine fungal strains were isolated countrywide from 10 Vietnamese soils, in areas both with and without a history of exposure to Agent Orange, and their degrading activities on the phenoxy acid herbicides 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), as well as related compounds, were examined. Among taxonomically various fungi, 45, 12 and 4% of the isolates degraded phenoxyacetic acid (PA), 2,4-D and 2,4,5-T, respectively. While the PA-degrading fungi were distributed to all sites and among many genera, the 2,4-D-degraders were found only in order Eurotiales in class Eurotiomycetes. All of the 2,4,5-T-degrading fungal strains were phylogenetically close to Eupenicillium spp. and were isolated from southern Vietnam. As a degradation intermediate, the corresponding phenol compounds were detected in some strains. The degradation substrate spectrum for 26 compounds of Eupenicillium spp. strains including 2,4,5-T-degraders and -non-degraders seemed to be related to phylogenetic similarity and soil sampling location of the isolates. These results suggest that the heavily contaminated environments enhanced the adaptation of the phylogenetic group of Eupenicillium spp. toward to obtain the ability to degrade 2,4,5-T. PMID:23167922

  7. Atmospheric Pressure Plasma Jet in Organic Solution: Spectra, Degradation Effects of Solution Flow Rate and Initial pH Value

    NASA Astrophysics Data System (ADS)

    Chen, Bingyan; Zhu, Changping; Chen, Longwei; Fei, Juntao; Gao, Ying; Wen, Wen; Shan, Minglei; Ren, Zhaoxing

    2014-12-01

    The organic compounds of p-nitrophenol (PNP) solution was treated by the active species generated in a stirred reactor by an atmospheric pressure plasma jet (APPJ). The emission intensities of hydroxyl (OH), oxygen (O), nitric oxide (NO), hydrogen (H) and molecular (N2) were measured by optical emission spectroscopy (OES). The relations between the flow rates of the PNP solution and degradation, the degradation effects and initial pH value of the solution were also investigated. Experimental results show that there exist intense emissions of O (777.1 nm), N2 (337.1 nm), OH (306-310 nm) and NO band (200-290 nm) in the region of plasma. Given the treatment time and gas flow rate, the degradation increased as a function of discharge energy and solution flow rate, respectively. The solution flow rate for the most efficient degradation ranged from 1.414 m/s to 1.702 m/s, and contributed very little when it exceeded 2.199 m/s. This indicates the existence of diffusion-controlled reactions at a low solution flow rate and activation-controlled reactions at a high solution flow rate. Moreover, increasing or decreasing the initial pH value of neutral PNP solution (pH=5.95) could improve the degradation efficiency. Treated by APPJ, the PNP solutions with different initial pH values of 5.95, 7.47 and 2.78 turned more acidic in the end, while the neutral solution had the lowest degradation efficiency. This work clearly demonstrates the close coupling of active species, photolysis of ultraviolet, the organic solution flow rate and the initial pH value, and thus is helpful in the study of the mechanism and application of plasma in wastewater treatment.

  8. Suppression of muscle protein turnover and amino acid degradation by dietary protein deficiency

    NASA Technical Reports Server (NTRS)

    Tawa, N. E. Jr; Goldberg, A. L.

    1992-01-01

    To define the adaptations that conserve amino acids and muscle protein when dietary protein intake is inadequate, rats (60-70 g final wt) were fed a normal or protein-deficient (PD) diet (18 or 1% lactalbumin), and their muscles were studied in vitro. After 7 days on the PD diet, both protein degradation and synthesis fell 30-40% in skeletal muscles and atria. This fall in proteolysis did not result from reduced amino acid supply to the muscle and preceded any clear decrease in plasma amino acids. Oxidation of branched-chain amino acids, glutamine and alanine synthesis, and uptake of alpha-aminoisobutyrate also fell by 30-50% in muscles and adipose tissue of PD rats. After 1 day on the PD diet, muscle protein synthesis and amino acid uptake decreased by 25-40%, and after 3 days proteolysis and leucine oxidation fell 30-45%. Upon refeeding with the normal diet, protein synthesis also rose more rapidly (+30% by 1 day) than proteolysis, which increased significantly after 3 days (+60%). These different time courses suggest distinct endocrine signals for these responses. The high rate of protein synthesis and low rate of proteolysis during the first 3 days of refeeding a normal diet to PD rats contributes to the rapid weight gain ("catch-up growth") of such animals.

  9. Assessment of chloroethene degradation rates based on ratios of daughter/parent compounds in groundwater plumes

    NASA Astrophysics Data System (ADS)

    Höhener, Patrick

    2014-05-01

    Chlorinated solvent spills at industrial and urban sites create groundwater plumes where tetrachloro- and trichloroethene may degrade to their daughter compounds, dichloroethenes, vinyl chloride and ethane. The assessment of degradation and natural attenuation at such sites may be based on the analysis and inverse modelling of concentration data, on the calculation of mass fluxes in transsects, and/or on the analysis of stable isotope ratios in the ethenes. Relatively few work has investigated the possibility of using ratio of concentrations for gaining information on degradation rates. The use of ratios bears the advantage that dilution of a single sample with contaminant-free water does not matter. It will be shown that molar ratios of daughter to parent compounds measured along a plume streamline are a rapid and robust mean of determining whether degradation rates increase or decrease along the degradation chain, and allow furthermore a quantitation of the relative magnitude of degradation rates compared to the rate of the parent compound. Furthermore, ratios of concentration will become constant in zones where degradation is absent, and this allows to sketching the extension of actively degrading zones. The assessment is possible for pure sources and also for mixed sources. A quantification method is proposed in order to estimate first-order degradation rates in zones of constant degradation activity. This quantification method includes corrections that are needed due to longitudinal and transversal dispersivity. The method was tested on a number of real field sites from literature. At the majority of these sites, the first-order degradation rates were decreasing along the degradation chain from tetrachloroethene to vinyl chloride, meaning that the latter was often reaching important concentrations. This is bad news for site owners due to the increased toxicity of vinyl chloride compared to its parent compounds.

  10. Degradation of Amino Acids and Structure in Model Proteins and Bacteriophage MS2 by Chlorine, Bromine, and Ozone.

    PubMed

    Choe, Jong Kwon; Richards, David H; Wilson, Corey J; Mitch, William A

    2015-11-17

    Proteins are important targets of chemical disinfectants. To improve the understanding of disinfectant-protein reactions, this study characterized the disinfectant:protein molar ratios at which 50% degradation of oxidizable amino acids (i.e., Met, Tyr, Trp, His, Lys) and structure were observed during HOCl, HOBr, and O3 treatment of three well-characterized model proteins and bacteriophage MS2. A critical question is the extent to which the targeting of amino acids is driven by their disinfectant rate constants rather than their geometrical arrangement. Across the model proteins and bacteriophage MS2 (coat protein), differing widely in structure, methionine was preferentially targeted, forming predominantly methionine sulfoxide. This targeting concurs with its high disinfectant rate constants and supports its hypothesized role as a sacrificial antioxidant. Despite higher HOCl and HOBr rate constants with histidine and lysine than for tyrosine, tyrosine generally was degraded in preference to histidine, and to a lesser extent, lysine. These results concur with the prevalence of geometrical motifs featuring histidines or lysines near tyrosines, facilitating histidine and lysine regeneration upon Cl[+1] transfer from their chloramines to tyrosines. Lysine nitrile formation occurred at or above oxidant doses where 3,5-dihalotyrosine products began to degrade. For O3, which lacks a similar oxidant transfer pathway, histidine, tyrosine, and lysine degradation followed their relative O3 rate constants. Except for its low reactivity with lysine, the O3 doses required to degrade amino acids were as low as or lower than for HOCl or HOBr, indicating its oxidative efficiency. Loss of structure did not correlate with loss of particular amino acids, suggesting the need to characterize the oxidation of specific geometric motifs to understand structural degradation. PMID:26488608

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

    PubMed

    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

  12. Polysorbate 20 Degradation in Biopharmaceutical Formulations: Quantification of Free Fatty Acids, Characterization of Particulates, and Insights into the Degradation Mechanism.

    PubMed

    Tomlinson, Anthony; Demeule, Barthélemy; Lin, Baiwei; Yadav, Sandeep

    2015-11-01

    Polysorbate 20 (PS20), a commonly used surfactant in biopharmaceuticals, showed degradation upon long-term (∼18-36 months) storage of two monoclonal antibody (mAb, mAb-A, and mAb-B) drug products at 2-8 °C. The PS20 degradation resulted in the accumulation of free fatty acids (FFA), which ultimately precipitated to form particles upon long-term storage. This study documents the development, qualification, and application of a method for FFA quantification in soluble and insoluble fraction of protein formulation. The method was applied to the quantification of capric acid, lauric acid, myristic acid, palmitic/oleic acid, and stearic acid in placebo as well as active protein formulations on stability. Quantification of FFA in both the soluble and insoluble fraction of mAb-A and mAb-B provided a better mechanistic understanding of PS20 degradation and the dynamics of subsequent fatty acid particle formation. Additionally, the use of this method for monitoring and quantitation of the FFA on real time storage stability appears to aid in identifying batches with higher probability for particulate formation upon extended storage at 5 °C. PMID:26419339

  13. Hydrolysis of VX on concrete: rate of degradation by direct surface interrogation using an ion trap secondary ion mass spectrometer.

    PubMed

    Groenewold, Gary S; Williams, John M; Appelhans, Anthony D; Gresham, Garold L; Olson, John E; Jeffery, Mark T; Rowland, Brad

    2002-11-15

    The nerve agent VX (O-ethyl S-2-diisopropylaminoethyl methylphosphonothiolate) is lethal at very low levels of exposure, which can occur by dermal contact with contaminated surfaces. Hence, behavior of VX in contact with common urban or industrial surfaces is a subject of acute interest. In the present study, VX was found to undergo complete degradation when in contact with concrete surfaces. The degradation was directly interrogated at submonolayer concentrations by periodically performing secondary ion mass spectrometry (SIMS) analyses after exposure of the concrete to VX. The abundance of the [VX + H]+ ion in the SIMS spectra was observed to decrease in an exponential fashion, consistent with first-order or pseudo-first-order behavior. This phenomenon enabled the rate constant to be determined at 0.005 min(-1) at 25 degrees C, which corresponds to a half-life of about 3 h on the concrete surface. The decrease in [VX + H]+ was accompanied by an increase in the abundance of the principal degradation product diisopropylaminoethanethiol (DESH), which arises by cleavage of the P-S bond. Degradation to form DESH is accompanied by the formation of ethyl methylphosphonic acid, which is observable only in the negative ion spectrum. A second degradation product was also implicated, which corresponded to a diisopropylvinylamine isomer (perhaps N,N-diisopropyl aziridinium) that arose via cleavage of the S-C bond. No evidence was observed for the formation of the toxic S-2-diisopropylaminoethyl methylphosphonothioic acid. The degradation rate constants were measured at four different temperatures (24-50 degrees C), which resulted in a linear Arrhenius relationship and an activation energy of 52 kJ mol(-1). This value agrees with previous values observed for VX hydrolysis in alkaline solutions, which suggests that the degradation of submonolayer VX is dominated by alkaline hydrolysis within the adventitious water film on the concrete surface. PMID:12487301

  14. Hydrolysis of VX on Concrete: Rate of Degradation by Direct Surface Interrogation using an Ion Trap Secondary Ion Mass Spectrometer

    SciTech Connect

    Groenewold, Gary Steven; Appelhans, Anthony David; Gresham, Garold Linn; Olson, John Eric; Rowland, B.; Williams, j.; Jeffery, M. T.

    2002-09-01

    The nerve agent VX (O-ethyl S-2-diisopropylaminoethyl methylphosphonothiolate) is lethal at very low levels of exposure, which can occur by dermal contact with contaminated surfaces. Hence, behavior of VX in contact with common urban or industrial surfaces is a subject of acute interest. In the present study, VX was found to undergo complete degradation when in contact with concrete surfaces. The degradation was directly interrogated at submonolayer concentrations by periodically performing secondary ion mass spectrometry (SIMS) analyses after exposure of the concrete to VX. The abundance of the [VX + H]+ ion in the SIMS spectra was observed to decrease in an exponential fashion, consistent with first-order or pseudo-first-order behavior. This phenomenon enabled the rate constant to be determined at 0.005 min-1 at 25 C, which corresponds to a half-life of about 3 h on the concrete surface. The decrease in [VX + H]+ was accompanied by an increase in the abundance of the principal degradation product diisopropylaminoethanethiol (DESH), which arises by cleavage of the P-S bond. Degradation to form DESH is accompanied by the formation of ethyl methylphosphonic acid, which is observable only in the negative ion spectrum. A second degradation product was also implicated, which corresponded to a diisopropylvinylamine isomer (perhaps N,N-diisopropyl aziridinium) that arose via cleavage of the S-C bond. No evidence was observed for the formation of the toxic S-2-diisopropylaminoethyl methylphosphonothioic acid. The degradation rate constants were measured at four different temperatures (24-50 C), which resulted in a linear Arrhenius relationship and an activation energy of 52 kJ mol-1. This value agrees with previous values observed for VX hydrolysis in alkaline solutions, which suggests that the degradation of submonolayer VX is dominated by alkaline hydrolysis within the adventitious water film on the concrete surface.

  15. Enhanced biofilm production by a toluene-degrading Rhodococcus observed after exposure to perfluoroalkyl acids.

    PubMed

    Weathers, Tess S; Higgins, Christopher P; Sharp, Jonathan O

    2015-05-01

    This study focuses on interactions between aerobic soil-derived hydrocarbon degrading bacteria and a suite of perfluorocarboxylic acids and perfluoroalkylsulfonates that are found in aqueous film-forming foams used for fire suppression. No effect on toluene degradation rate or induction time was observed when active cells of Rhodococcus jostii strain RHA1 were exposed to toluene and a mixture of perfluoroalkyl acids (PFAAs) including perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS) at concentrations near the upper bounds of groundwater relevance (11 PFAAs at 10 mg/L each). However, exposure to aqueous PFAA concentrations above 2 mg/L (each) was associated with enhanced aggregation of bacterial cells and significant increases in extracellular polymeric substance production. Flocculation was only observed during exponential growth and not elicited when PFAAs were added to resting incubations; analogous flocculation was also observed in soil enrichments. Aggregation was accompanied by 2- to 3-fold upregulation of stress-associated genes, sigF3 and prmA, during growth of this Rhodococcus in the presence of PFAAs. These results suggest that biological responses, such as microbial stress and biofilm formation, could be more prominent than suppression of co-contaminant biodegradation in subsurface locations where poly- and perfluoroalkyl substances occur with hydrocarbon fuels. PMID:25806435

  16. Starch degradation in chloroplasts isolated from C3 or CAM (crassulacean acid metabolism)-induced Mesembryanthemum crystallinum L.

    PubMed Central

    Neuhaus, H E; Schulte, N

    1996-01-01

    C3 or crassulacean acid metabolism (CAM)-induced Mesembryanthemum crystallinum plants perform nocturnal starch degradation which is linear with time. To analyse the composition of metabolites released by isolated leaf chloroplasts during starch degradation we developed a protocol for the purification of starch-containing plastids. Isolated chloroplasts from C3 or CAM-induced M. crystallinum plants are also able to degrade starch. With respect to the endogenous starch content of isolated plastids the rate of starch degradation in intact leaves. The combined presence of Pi, ATP, and oxaloacetate is identified to be the most positive effector combination to induce starch mobilization. The metabolic flux through the oxidative pentose-phosphate pathway in chloroplasts isolated from CAM-induced M. crystallinum is less than 3.5% compared with other metabolic routes of starch degradation. Here we report that starch-degrading chloroplasts isolated from CAM-induced M. crystallinum plants use exogenously supplied oxaloacetate for the synthesis of malate. The main products of starch degradation exported into the incubation medium by these chloroplasts are glucose 6-phosphate, 3-phosphoglyceric acid, dihydroxyacetone phosphate and glucose. The identification of glucose 6-phosphate as an important metabolite released during starch degradation is in contrast to the observations made on all other types of plastids analysed so far, including chloroplasts isolated from M. crystallinum in the C3 state. Therefore, we analysed the transport properties of isolated chloroplasts from M. crystallinum. Surprisingly, both types of chloroplasts, isolated from either C3 or CAM-induced plants, are able to transport glucose 6-phosphate in counter exchange with endogenous Pi, indicating the presence of a glucose 6-phosphate translocator as recently demonstrated to occur in other types of plastids. The composition of metabolites released and the stimulatory effect of oxaloacetate on the rate of

  17. Degradation of extracellular matrix and its components by hypobromous acid

    PubMed Central

    Rees, Martin D.; McNiven, Tane N.; Davies, Michael J.

    2006-01-01

    EPO (eosinophil peroxidase) and MPO (myeloperoxidase) are highly basic haem enzymes that can catalyse the production of HOBr (hypobromous acid). They are released extracellularly by activated leucocytes and their binding to the polyanionic glycosa-minoglycan components of extracellular matrix (proteoglycans and hyaluronan) may localize the production of HOBr to these materials. It is shown in the present paper that the reaction of HOBr with glycosaminoglycans (heparan sulfate, heparin, chondroitin sulfate and hyaluronan) generates polymer-derived N-bromo derivatives (bromamines, dibromamines, N-bromosulfon-amides and bromamides). Decomposition of these species, which can occur spontaneously and/or via one-electron reduction by low-valent transition metal ions (Cu+ and Fe2+), results in polymer fragmentation and modification. One-electron reduction of the N-bromo derivatives generates radicals that have been detected by EPR spin trapping. The species detected are consistent with metal ion-dependent polymer fragmentation and modification being initiated by the formation of nitrogen-centred (aminyl, N-bromoaminyl, sulfonamidyl and amidyl) radicals. Previous studies have shown that the reaction of HOBr with proteins generates N-bromo derivatives and results in fragmentation of the polypeptide backbone. The reaction of HOBr with extracellular matrix synthesized by smooth muscle cells in vitro induces the release of carbohydrate and protein components in a time-dependent manner, which is consistent with fragmentation of these materials via the formation of N-bromo derivatives. The degradation of extracellular matrix glycosaminoglycans and proteins by HOBr may contribute to tissue damage associated with inflammatory diseases such as asthma. PMID:17014424

  18. Microbiological degradation of bile acids. Nitrogenous hexahydroindane derivatives formed from cholic acid by Streptomyces rubescens.

    PubMed Central

    Hayakawa, S; Hashimoto, S; Onaka, T

    1976-01-01

    The metabolism of cholic acid (I) by Streptomyces rubescens was investigated. This organism effected ring A cleavage, side-chain shortening and amide bond formation and gave the following metabolites: (4R)-4-[4alpha-(2-carboxyethyl)-3aalpha-hexahydro-7abeta-methyl-5-oxoindan-1 beta-yl]valeric acid (IIa) and its mono-amide (valeramide) (IIb); and 2,3,4,6, 6abeta,7,8,9,9aalpha,9bbeta-decahydro-6abeta-methyl-1H-cyclopenta[f]quinoline-3,7-dione(IIIe)and its homologues with the beta-oriented side chains, valeric acid, valeramide, butanone and propionic acid, in the place of the oxo group at C-7, i.e.compounds (IIIa), (IIIb), (IIIc) and (IIId) respectively. All the nitrogenous metabolites were new compounds, and their structures were established by partial synthesis except for the metabolite (IIIc). The mechanism of formation of these metabolites is considered. A degradative pathway of cholic acid (I) into the metabolites is also tentatively proposed. PMID:1016253

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

    PubMed Central

    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

  20. Isolation of Soil Bacteria Adapted To Degrade Humic Acid-Sorbed Phenanthrene

    PubMed Central

    Vacca, D. J.; Bleam, W. F.; Hickey, W. J.

    2005-01-01

    The goal of these studies was to determine how sorption by humic acids affected the bioavailability of polynuclear aromatic hydrocarbons (PAHs) to PAH-degrading microbes. Micellar solutions of humic acid were used as sorbents, and phenanthrene was used as a model PAH. Enrichments from PAH-contaminated soils established with nonsorbed phenanthrene yielded a total of 25 different isolates representing a diversity of bacterial phylotypes. In contrast, only three strains of Burkholderia spp. and one strain each of Delftia sp. and Sphingomonas sp. were isolated from enrichments with humic acid-sorbed phenanthrene (HASP). Using [14C]phenanthrene as a radiotracer, we verified that only HASP isolates were capable of mineralizing HASP, a phenotype hence termed “competence.” Competence was an all-or-nothing phenotype: noncompetent strains showed no detectable phenanthrene mineralization in HASP cultures, but levels of phenanthrene mineralization effected by competent strains in HASP and NSP cultures were not significantly different. Levels and rates of phenanthrene mineralization exceeded those predicted to be supported solely by the metabolism of phenanthrene in the aqueous phase of HASP cultures. Thus, competent strains were able to directly access phenanthrene sorbed by the humic acids and did not rely on desorption for substrate uptake. To the best of our knowledge, this is the first report of (i) a selective interaction between aerobic bacteria and humic acid molecules and (ii) differential bioavailability to bacteria of PAHs sorbed to a natural biogeopolymer. PMID:16000791

  1. Isolation and Characterization of Thermophilic Bacilli Degrading Cinnamic, 4-Coumaric, and Ferulic Acids

    PubMed Central

    Peng, Xue; Misawa, Norihiko; Harayama, Shigeaki

    2003-01-01

    Thirty-four thermophilic Bacillus sp. strains were isolated from decayed wood bark and a hot spring water sample based on their ability to degrade vanillic acid under thermophilic conditions. It was found that these bacteria were able to degrade a wide range of aromatic acids such as cinnamic, 4-coumaric, 3-phenylpropionic, 3-(p-hydroxyphenyl)propionic, ferulic, benzoic, and 4-hydroxybenzoic acids. The metabolic pathways for the degradation of these aromatic acids at 60°C were examined by using one of the isolates, strain B1. Benzoic and 4-hydroxybenzoic acids were detected as breakdown products from cinnamic and 4-coumaric acids, respectively. The β-oxidative mechanism was proposed to be responsible for these conversions. The degradation of benzoic and 4-hydroxybenzoic acids was determined to proceed through catechol and gentisic acid, respectively, for their ring fission. It is likely that a non-β-oxidative mechanism is the case in the ferulic acid catabolism, which involved 4-hydroxy-3-methoxyphenyl-β-hydroxypropionic acid, vanillin, and vanillic acid as the intermediates. Other strains examined, which are V0, D1, E1, G2, ZI3, and H4, were found to have the same pathways as those of strain B1, except that strains V0, D1, and H4 had the ability to transform 3-hydroxybenzoic acid to gentisic acid, which strain B1 could not do. PMID:12620824

  2. The radiation-induced degradation of hyaluronic acid

    NASA Astrophysics Data System (ADS)

    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].

  3. Hydroxide based Benzyltrimethylammonium degradation: Quantification of rates and degradation technique development

    SciTech Connect

    Sturgeon, Matthew R.; Macomber, Clay S.; Engtrakul, Chaiwat; Long, Hai; Pivovar, Bryan S.

    2015-01-21

    Anion exchange membranes (AEMs) are of interest as hydroxide conducting polymer electrolytes in electrochemical devices like fuel cells and electrolyzers. AEMs require hydroxide stable covalently tetherable cations to ensure required conductivity. Benzyltrimethylammonium (BTMA) has been the covalently tetherable cation that has been most often employed in anion exchange membranes because it is reasonably basic, compact (limited number of atoms per charge), and easily/cheaply synthesized. Several reports exist that have investigated hydroxide stability of BTMA under specific conditions, but consistency within these reports and comparisons between them have not yet been made. While the hydroxide stability of BTMA has been believed to be a limitation for AEMs, this stability has not been thoroughly reported. In this paper, we have found that several methods reported have inherent flaws in their findings due to the difficulty of performing degradation experiments at high temperature and high pH. In order to address these shortcomings, we have developed a reliable, standardized method of determining cation degradation under conditions similar/relevant to those expected in electrochemical devices. The experimental method has been employed to determine BTMA stabilities at varying cation concentrations and elevated temperatures, and has resulted in improved experimental accuracy and reproducibility. Finally and most notably, these results have shown that BTMA is quite stable at 80°C (half-life of ~4 years), a significant increase in stability over what had been reported previously.

  4. Hydroxide based Benzyltrimethylammonium degradation: Quantification of rates and degradation technique development

    DOE PAGESBeta

    Sturgeon, Matthew R.; Macomber, Clay S.; Engtrakul, Chaiwat; Long, Hai; Pivovar, Bryan S.

    2015-01-21

    Anion exchange membranes (AEMs) are of interest as hydroxide conducting polymer electrolytes in electrochemical devices like fuel cells and electrolyzers. AEMs require hydroxide stable covalently tetherable cations to ensure required conductivity. Benzyltrimethylammonium (BTMA) has been the covalently tetherable cation that has been most often employed in anion exchange membranes because it is reasonably basic, compact (limited number of atoms per charge), and easily/cheaply synthesized. Several reports exist that have investigated hydroxide stability of BTMA under specific conditions, but consistency within these reports and comparisons between them have not yet been made. While the hydroxide stability of BTMA has been believedmore » to be a limitation for AEMs, this stability has not been thoroughly reported. In this paper, we have found that several methods reported have inherent flaws in their findings due to the difficulty of performing degradation experiments at high temperature and high pH. In order to address these shortcomings, we have developed a reliable, standardized method of determining cation degradation under conditions similar/relevant to those expected in electrochemical devices. The experimental method has been employed to determine BTMA stabilities at varying cation concentrations and elevated temperatures, and has resulted in improved experimental accuracy and reproducibility. Finally and most notably, these results have shown that BTMA is quite stable at 80°C (half-life of ~4 years), a significant increase in stability over what had been reported previously.« less

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

    DOEpatents

    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.

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

    PubMed

    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 TMPGDEdegradation amounts of TA from p(TA) nanoparticles can be controlled by the appropriate choice of crosslinker, and the pH of releasing media. The highest TA release, 600mg/g, was obtained for TMPGDE-crosslinked p(TA) particles in intestinal pH conditions (pH 9) over 3 days; whereas, a slow and linear TA release profile over almost 30 days was obtained by using PEGGE-crosslinked p(TA) in body fluid pH conditions (pH 7.4). The total phenol content of p(TA) particles was calculated as 70±1μgmL(-1) for 170μgmL(-1) p(TA), and the trolox equivalent antioxidant capacity was found to be 2027±104mM trolox equivalent g(-1). Moreover, p(TA) nanoparticles demonstrated strong antimicrobial effects against common bacterial strains. More interestingly, with a higher concentration of p(TA) particles, higher blood clotting indices were obtained. PMID:26970821

  7. Degradable Cationic Shell Crosslinked Knedel-like Nanoparticles: Synthesis, degradation, nucleic acid binding and in vitro evaluation

    PubMed Central

    Samarajeewa, Sandani; Ibricevic, Aida; Gunsten, Sean P.; Shrestha, Ritu; Elsabahy, Mahmoud; Brody, Steven L.; Wooley, Karen L.

    2013-01-01

    In this work, degradable cationic shell crosslinked knedel-like (deg-cSCK) nanoparticles were developed as an alternative platform to replace similar non-degradable cSCK nanoparticles that have been utilized for nucleic acids delivery. An amphiphilic diblock copolymer poly(acrylamidoethylamine)90-block-poly(DL-lactide)40 (PAEA90-b-PDLLA40) was synthesized, self-assembled in aqueous solution and shell crosslinked using a hydrolyzable crosslinker to afford deg-cSCKs with an average core diameter of 45 ± 7 nm. These nanoparticles were fluorescently labeled for in vitro tracking. The enzymatic- and hydrolytic-degradability, siRNA binding affinity, cell uptake and cytotoxicity of the deg-cSCKs were evaluated. Esterase-catalyzed hydrolysis of the nanoparticles resulted in the degradation of ca. 24% of the PDLLA core into lactic acid within 5 d, as opposed to only ca. 9% degradation from aqueous solutions of the deg-cSCK nanoparticles in the absence of enzyme. Cellular uptake of deg-cSCKs was efficient, while exhibiting low cytotoxicity with LD50 values of ca. 90 μg/mL and 30 μg/mL in RAW 264.7 mouse macrophages and MLE 12 cell lines, respectively, ca. 5–6-fold lower than the cytotoxicity observed for non-degradable cSCK analogs. Additionally, deg-cSCKs were able to complex siRNA at an N/P ratio as low as 2, and were efficiently able to facilitate cellular uptake of the complexed nucleic acids. PMID:23510389

  8. Degradation of 3-phenylbutyric acid by Pseudomonas sp.

    PubMed Central

    Sariaslani, F S; Sudmeier, J L; Focht, D D

    1982-01-01

    Pseudomonas sp. isolated by selective culture with 3-phenylbutyrate (3-PB) as the sole carbon source metabolized the compound through two different pathways by initial oxidation of the benzene ring and by initial oxidation of the side chain. During early exponential growth, a catechol substance identified as 3-(2,3-dihydroxyphenyl)butyrate (2,3-DHPB) and its meta-cleavage product 2-hydroxy-7-methyl-6-oxononadioic-2,4-dienoic acid were produced. These products disappeared during late exponential growth, and considerable amounts of 2,3-DHPB reacted to form brownish polymeric substances. The catechol intermediate 2,3-DHPB could not be isolated, but cell-free extracts were able only to oxidize 3-(2,3-dihydroxyphenyl)propionate of all dihydroxy aromatic acids tested. Moreover, a reaction product caused by dehydration of 2,3-DHPB on silica gel was isolated and identified by spectral analysis as (--)-8-hydroxy-4-methyl-3,4-dihydrocoumarin. 3-Phenylpropionate and a hydroxycinnamate were found in supernatants of cultures grown on 3-PB; phenylacetate and benzoate were found in supernatants of cultures grown on 3-phenylpropionate; and phenylacetate was found in cultures grown on cinnamate. Cells grown on 3-PB rapidly oxidized 3-phenylpropionate, cinnamate, catechol, and 3-(2,3-dihydroxyphenyl)propionate, whereas 2-phenylpropionate, 2,3-dihydroxycinnamate, benzoate, phenylacetate, and salicylate were oxidized at much slower rates. Phenylsuccinate was not utilized for growth nor was it oxidized by washed cell suspensions grown on 3-PB. However, dual axenic cultures of Pseudomonas acidovorans and Klebsiella pneumoniae, which could not grow on phenylsuccinate alone, could grow syntrophically and produced the same metabolites found during catabolism of 3-PB by Pseudomonas sp. Washed cell suspensions of dual axenic cultures also immediately oxidized phenylsuccinate, 3-phenylpropionate, cinnamate, phenylacetate, and benzoate. PMID:7118830

  9. Effect of application rate on fumigant degradation in five agricultural soils.

    PubMed

    Qin, Ruijun; Gao, Suduan; Ajwa, Husein; Hanson, Bradley D

    2016-01-15

    Soil fumigation is an important pest management tool for many high value crops. To address the knowledge gap of how fumigant concentration in soil impacts dissipation, and thereby efficacy, this research determined the degradation characteristics of four fumigants as affected by application rate. Laboratory incubation experiments were conducted to determine degradation rates of 1,3-dichloropropene (both cis- and trans isomers), chloropicrin (CP), dimethyl disulfide (DMDS), and methyl iodide (MeI) in five agricultural soils. Fitted to pseudo first-order kinetics, the degradation rate constant (k) of CP, DMDS, and MeI decreased significantly as application rate increased while the 1,3-D isomers were the least affected by rate. Half-lives increased 12, 17, and 6-fold for CP, DMDS, and MeI, respectively, from the lowest to the highest application rate. At low application rates, the degradation rate of all fumigants in the Hueneme sandy loam soil was reduced by 50-95% in sterilized soil compared to the biologically active controls. However, this difference became much smaller or disappeared at high application rates indicating that biodegradation dominates at low concentrations but chemical degradation is more important at high concentrations. When co-applied, CP degradation was enhanced with biodegradation remained above 50%, while 1,3-D degradation was either reduced or not changed. Among the fumigants tested, the relative importance of biodegradation was DMDS>CP>MeI>1,3-D. These results are useful for determining effective fumigation rates and for informing regulatory decisions on emission controls under different fumigation scenarios. PMID:26439645

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

    NASA Astrophysics Data System (ADS)

    Araújo, M. M.; Marchioni, E.; Zhao, M.; Kuntz, F.; Di Pascoli, T.; Villavicencio, A. L. C. H.; Bergaentzle, M.

    2012-08-01

    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.

  11. Comparison of degradation reactions of Acid Yellow 61 in both oxidation processes of H2O2/UV and O3.

    PubMed

    Wang, Y Z; Yedeler, A; Kettrup, A

    2001-07-01

    The comparison of degradation of Acid Yellow 61 as a model dye compound in both oxidation processes of H2O2/UV and O3 has been studied. When the decolorization rate of Acid Yellow 61 in both reactions presented similar, it was found there are some differences from the results of AOX removal and production of inorganic ions and organic acids. The results reveal that the H2O2/UV has beneficial effect on mineralization than O3 only for degradation of Acid Yellow 61 solution and it is possible for enhancement of method efficiency by taking longer reaction time and addition of high concentration of oxidants. PMID:11590760

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

    SciTech Connect

    Miyoshi, Hideaki; Uchida, Hiroyuki; Watanabe, Masahiro

    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}.

  13. Calcite crystal growth rate inhibition by polycarboxylic acids

    USGS Publications Warehouse

    Reddy, M.M.; Hoch, A.R.

    2001-01-01

    Calcite crystal growth rates measured in the presence of several polycarboxyclic acids show that tetrahydrofurantetracarboxylic acid (THFTCA) and cyclopentanetetracarboxylic acid (CPTCA) are effective growth rate inhibitors at low solution concentrations (0.01 to 1 mg/L). In contrast, linear polycarbocylic acids (citric acid and tricarballylic acid) had no inhibiting effect on calcite growth rates at concentrations up to 10 mg/L. Calcite crystal growth rate inhibition by cyclic polycarboxyclic acids appears to involve blockage of crystal growth sites on the mineral surface by several carboxylate groups. Growth morphology varied for growth in the absence and in the presence of both THFTCA and CPTCA. More effective growth rate reduction by CPTCA relative to THFTCA suggests that inhibitor carboxylate stereochemical orientation controls calcite surface interaction with carboxylate inhibitors. ?? 20O1 Academic Press.

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

    PubMed Central

    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

  15. In vitro and in vivo degradation of porous poly(DL-lactic-co-glycolic acid) foams.

    PubMed

    Lu, L; Peter, S J; Lyman, M D; Lai, H L; Leite, S M; Tamada, J A; Uyama, S; Vacanti, J P; Langer, R; Mikos, A G

    2000-09-01

    foams exhibited significantly faster degradation in vivo as compared to in vitro conditions due to an autocatalytic effect of the accumulated acidic degradation products in the medium surrounding the implants. These results suggest that the polymer composition and environmental conditions have significant effects on the degradation rate of porous PLGA foams. PMID:10919687

  16. Abiotic degradation rates for carbon tetrachloride and chloroform: Final report.

    SciTech Connect

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

    2012-12-01

    This report documents the objectives, technical approach, and progress made through FY 2012 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 project also sought to explore the possible effects of contact with minerals and sediment (i.e., heterogeneous hydrolysis) on these rates. We conducted 114 hydrolysis rate experiments in sealed vessels across a temperature range of 20-93 °C for periods as long as 6 years, and used the Arrhenius equation to estimate activation energies and calculate half-lives for typical Hanford groundwater conditions (temperature of 16 °C and pH of 7.75). We calculated a half-life of 630 years for hydrolysis for CT under these conditions and found that CT hydrolysis was unaffected by contact with sterilized, oxidized minerals or Hanford sediment within the sensitivity of our experiments. In contrast to CT, hydrolysis of CF was generally slower and very sensitive to pH due to the presence of both neutral and base-catalyzed hydrolysis pathways. We calculated a half-life of 3400 years for hydrolysis of CF in homogeneous solution at 16 °C and pH 7.75. Experiments in suspensions of Hanford sediment or smectite, the dominant clay mineral in Hanford sediment, equilibrated to an initial pH of 7.2, yielded calculated half-lives of 1700 years and 190 years, respectively, at 16 °C. Experiments with three other mineral phases at the same pH (muscovite mica, albite feldspar, and kaolinite) showed no change from the homogeneous solution results (i.e., a half-life of 3400 years). The strong influence of Hanford sediment on CF hydrolysis was attributed to the presence of smectite and its ability to adsorb protons, thereby buffering the solution pH at a higher level than would otherwise occur. The project also determined liquid-vapor partition coefficients for CT under the temperatures and pressures encountered in the sealed vessels that

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

    PubMed

    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

  18. Enhanced degradation of five organophosphorus pesticides in skimmed milk by lactic acid bacteria and its potential relationship with phosphatase production.

    PubMed

    Zhang, Ying-Hua; Xu, Di; Liu, Jia-Qi; Zhao, Xin-Huai

    2014-12-01

    Skimmed milk spiked with five organophosphorus pesticides (OPPs), chlorpyrifos, diazinon, fenitrothion, malathion and methyl parathion, was fermented by ten lactic acid bacteria (LAB) and four strain combinations at 42°C for 24h. OPPs left in the samples at different times were extracted, purified, detected by gas chromatography and calculated for degradation rate constants, based on a first-order reaction model. OPPs degradation was enhanced by the inoculated LAB, resulting in 0.8-225.4% increase in the rate constants. Diazinon and methyl parathion were more stable whereas chlorpyrifos, fenitrothion and malathion were more labile. Lactobacillus brevis 1.0209 showed the strongest acceleration on OPPs degradation while strain combination could bring about a synergy between the strains of lower ability. Phosphatase production of the strains might be one of the key factors responsible for the enhanced OPPs degradation, as the detected phosphatase activities were positively correlated to the measured degradation rate constants of OPPs (r=0.636-0.970, P<0.05). PMID:24996321

  19. Deoxyribonucleic Acid Degradation in Bacillus subtilis During Exposure to Actinomycin D1

    PubMed Central

    Farmer, James L.

    1968-01-01

    At high concentrations (10 μg/ml), actinomycin D inhibited deoxyribonucleic acid (DNA) synthesis in Bacillus subtilis. Inhibition occurred quickly (in less than 1 min) and was complete. In strain 23 thy his, inhibition of DNA synthesis by actinomycin D was followed by partial degradation of one of the two daughter strands to acid-soluble products. Degradation began at the replication point and proceeded over a distance equal to about 12% of a chromosome in length. Actinomycin D played some essential part in degradation, since exposure of the cells to other treatments or agents which inhibit growth did not lead to the above result. PMID:4967199

  20. Tailoring the degradation rates of thermally responsive hydrogels designed for soft tissue injection by varying the autocatalytic potential

    PubMed Central

    Zhu, Yang; Jiang, Hongbin; Ye, Sang-Ho; Yoshizumi, Tomo; Wagner, William R.

    2015-01-01

    The ability to modulate the degradation properties of biomaterials such as thermally responsive hydrogels is desirable when exploring new therapeutic strategies that rely on the temporary presence of a placed scaffold or gel. Here we report a method of manipulating the absorption rate of a poly(N-isopropylacrylamide) ((poly(NIPAAm)) based hydrogel across a wide range (from 1 d to 5 mo) by small alterations in the composition. Relying upon the autocatalytic effect, the degradation of poly(NIPAAm-co-HEMA-co-MAPLA), (HEMA=2-hydroxyethyl methacrylate; MAPLA=methacrylate-polylactide) was greatly accelerated by adding a fourth monomer methacrylic acid (MAA) at no more than 2 mol% to obtain poly(NIPAAm-co-HEMA-co-MAPLA-co-MAA) (pNHMMj) where j reflects the MAA molar % in the reactant mixture. MAA residue introduction decreased the pH inside the hydrogels and in surrounding buffered solutions. Accelerated degradation positively correlated with MAA content in pNHMMj polymers, putatively by the accelerated cleavage of MAPLA residues to raise the transition temperature of the polymer above body temperature. Physical properties including thermal transition behavior and initial mechanical strength did not vary significantly with MAA content. A rat hindlimb injection model generally reflected the in vitro observation that higher MAA content resulted in more rapid degradation and cellular infiltration. The strategy of tuning the degradation of thermally responsive hydrogels where degradation or solubilization is determined by their polyester components might be applied to other tissue engineering and regenerative medicine applications where designed biomaterial degradation behavior is needed. PMID:25890745

  1. Isolation and structure elucidation of a novel product of the acidic degradation of cefaclor.

    PubMed

    Baertschi, S W; Dorman, D E; Occolowitz, J L; Spangle, L A; Collins, M W; Wildfeuer, M E; Lorenz, L J

    1993-06-01

    The acidic aqueous degradation of cefaclor, an orally administered cephalosporin antibiotic, has been investigated. The most prominent peak in the high-performance liquid chromatography profile of a degraded solution of cefaclor was isolated by preparative high-performance liquid chromatography. Mechanistically, the formation of this degradent from cefaclor involves a condensation of two cefaclor degradation products in which both products have undergone contraction from a six-membered cephem ring to a five-membered thiazole ring, presumably via a common episulfonium ion intermediate. PMID:8331538

  2. Influence of Fenton's reagent doses on the degradation and mineralization of H-acid.

    PubMed

    Liu, Huanhuan; Chen, Quanyuan; Yu, Yang; Liu, Zhenhong; Xue, Gang

    2013-12-15

    The recalcitrant H-acid (1-amino-8-naphthol-3,6-disulfonic acid) in aqueous solution was oxidized by Fenton process, focusing on the relation of Fenton's reagent doses and degradation products. The experimental results showed that COD and TOC removals and biodegradability (BOD/COD ratio) of the solution increased with increasing Fenton's reagent doses. Over 80% COD can be removed and the biodegradability was improved significantly. It was found that major SO3H and NH2 groups in H-acid molecules were mineralized to SO4(2-) and NH4(+) ions during Fenton oxidation processes. H-acid degradation intermediates with benzene structures substituted by hydroxyl and/or carboxyl groups were identified by GC-MS. It was also found that short-chain fatty acids primarily oxalic acid were degradation products of H-acid by Fenton oxidation. Oxalic acid accumulated could account for approximately 60% of the residual TOC. The degradation pathway of H-acid was proposed based on above analyses in this work. PMID:24231329

  3. Stress degradation studies and stability-indicating TLC-densitometric method of glycyrrhetic acid

    PubMed Central

    2013-01-01

    Background Glycyrrhetic acid, a pentacyclic triterpenoid, possesses a broad range of pharmacological activities and serves as template to synthesize many bioactive drugs. This paper describes a simple, accurate, and sensitive stability-indicating TLC densitometric method for the determination of glycyrrhetic acid and its degradation product as per the ICH guidelines. Results Separation was carried out on TLC aluminium sheet pre-coated with silica gel 60F254 using chloroform, methanol and formic acid (9:0.9:0.1, v/v). Compact spot for glycyrrhetic acid was found at Rf value of 0.42 ± 0.03. Densitometric analysis was carried out in the absorbance mode at λmax 254 nm. Glycyrrhetic acid was found to be stable to the exposure of base, neutral, oxidation, dry heating treatment and wet heating treatment, but showed degradation under acidic and photochemical conditions. Moreover, fragmentation pattern of glycyrrhetic acid was developed by using a positive ion electrospray ionization quadrupole time-of-flight mass spectrometry (ESI-QqTOF-MS/MS) hybrid instrument. A photo-degraded product was characterized through comparison of mass spectrometric studies with glycyrrhetic acid. Conclusion The developed stability-indicating TLC-densitometric method can be applied for routine analysis of glycyrrhetic acid in the presence of its degradation products. PMID:23327365

  4. Antioxidant activities of fucoidan degraded by gamma irradiation and acidic hydrolysis

    NASA Astrophysics Data System (ADS)

    Lim, Sangyong; Choi, Jong-il; Park, Hyun

    2015-04-01

    Low molecular weight fucoidan, prepared by radical degradation using gamma ray was investigated for its antioxidant activities with different assay methods. As the molecular weight of fucoidan decreased with a higher absorbed dose, ferric-reducing antioxidant power values increased, but β-carotene bleaching inhibition did not change significantly. The antioxidant activity of acid-degraded fucoidan was also examined to investigate the effect of different degradation methods. At the same molecular weight, fucoidan degraded by gamma irradiation showed higher 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity than that observed with the acidic method. This result reveals that in addition to molecular weight, the degradation method affects the antioxidant activity of fucoidan.

  5. Capacity and peak power degradation of lead-acid battery under simulated electric vehicle operations

    NASA Astrophysics Data System (ADS)

    Lee, J.; Tummillo, A. F.; Miller, J. F.; Hornstra, F.; Christianson, C. C.

    In a program supported by the Electric Power Research Institute, controlled laboratory tests were conducted at Argonne to evaluate the effects of selected EV application factors on the performance and life of the EV-2300 lead-acid battery. These application factors included simulated driving profile discharges with different levels of peak power demands for vehicle acceleration, long rest times after charge or discharge, and different methods of recharging. The performance and life variations among cells and modules in a full-scale battery pack were also examined. Statistical methods were used to analyze the laboratory test data. The key factors affecting the performance and life of the battery were identified, and the rates of capacity and power degradation were quantified using multiple regression techniques. The analyses show that the most significant factors were peak power demand levels and cell location within the six-cell modules. The effects of charge method and rest times were found to be small.

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

    PubMed

    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

  7. Degradable cationic shell cross-linked knedel-like nanoparticles: synthesis, degradation, nucleic acid binding, and in vitro evaluation.

    PubMed

    Samarajeewa, Sandani; Ibricevic, Aida; Gunsten, Sean P; Shrestha, Ritu; Elsabahy, Mahmoud; Brody, Steven L; Wooley, Karen L

    2013-04-01

    In this work, degradable cationic shell cross-linked knedel-like (deg-cSCK) nanoparticles were developed as an alternative platform to replace similar nondegradable cSCK nanoparticles that have been utilized for nucleic acids delivery. An amphiphilic diblock copolymer poly(acrylamidoethylamine)(90)-block-poly(DL-lactide)(40) (PAEA(90)-b-PDLLA(40)) was synthesized, self-assembled in aqueous solution, and shell cross-linked using a hydrolyzable cross-linker to afford deg-cSCKs with an average core diameter of 45 ± 7 nm. These nanoparticles were fluorescently labeled for in vitro tracking. The enzymatic- and hydrolytic-degradability, siRNA binding affinity, cell uptake and cytotoxicity of the deg-cSCKs were evaluated. Esterase-catalyzed hydrolysis of the nanoparticles resulted in the degradation of ca. 24% of the PDLLA core into lactic acid within 5 d, as opposed to only ca. 9% degradation from aqueous solutions of the deg-cSCK nanoparticles in the absence of enzyme. Cellular uptake of deg-cSCKs was efficient, while exhibiting low cytotoxicity with LD50 values of ca. 90 and 30 μg/mL in RAW 264.7 mouse macrophages and MLE 12 cell lines, respectively, ca. 5- to 6-fold lower than the cytotoxicity observed for nondegradable cSCK analogs. Additionally, deg-cSCKs were able to complex siRNA at an N/P ratio as low as 2, and were efficiently able to facilitate cellular uptake of the complexed nucleic acids. PMID:23510389

  8. Mechanistic QSAR models for interpreting degradation rates of sulfonamides in UV-photocatalysis systems.

    PubMed

    Huang, Xiangfeng; Feng, Yi; Hu, Cui; Xiao, Xiaoyu; Yu, Daliang; Zou, Xiaoming

    2015-11-01

    Photocatalysis is one of the most effective methods for treating antibiotic wastewater. Thus, it is of great significance to determine the relationship between degradation rates and structural characteristics of antibiotics in photocatalysis processes. In the present study, the photocatalytic degradation characteristics of 10 sulfonamides (SAs) were studied using two photocatalytic systems composed of nanophase titanium dioxide (nTiO2) plus ultraviolet (UV) and nTiO2/activated carbon fiber (ACF) plus UV. The results indicated that the largest apparent SA degradation rate constant (Kapp) is approximately 5 times as large as that of the smallest one. Based on the degradation mechanism and the partial least squares regression (PLS) method, optimum Quantitative Structure Activity Relationship (QSAR) models were developed for the two systems. Mechanistic models indicated that the degradation rule of SAs in the TiO2 systems strongly relates to their highest occupied molecular orbital (Ehomo), the maximum values of nucleophilic attack (f(+)x), and the minimum values of the most negative partial charge on a main-chain atom (q(C)min), whereas the maximum values of OH radical attack (f(0)x) and the apparent adsorption rate constant values (kad) are key factors affecting the degradation rule of SAs in the TiO2/ACF system. PMID:26070083

  9. Selective microbial degradation of saturated methyl branched chain fatty acid isomers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Three strains of Pseudomonas bacteria were screened for their capabilities of degrading chemically synthesized saturated branched-chain fatty acids (sbc-FAs). Mixtures of sbc-FAs with the methyl-branch located at various locales along the fatty acid were used as a carbon feedstock in shake-flask cu...

  10. ADIPIC ACID DEGRADATION MECHANISM IN AQUEOUS FGD (FLUE GAS DESULFURIZATION) SYSTEMS

    EPA Science Inventory

    The report gives results of a field and laboratory study of the adipic acid degradation mechanism in aqueous flue gas desulfurization (FGD) systems. (Adding adipic acid to limestone-based, SO2 wet scrubbers increases SO2 removal and limestone utilization. However, as much as 80% ...

  11. Degradation of trans-ferulic acid in acidic aqueous medium by anodic oxidation, electro-Fenton and photoelectro-Fenton.

    PubMed

    Flores, Nelly; Sirés, Ignasi; Garrido, José Antonio; Centellas, Francesc; Rodríguez, Rosa María; Cabot, Pere Lluís; Brillas, Enric

    2016-12-01

    Solutions of pH 3.0 containing trans-ferulic acid, a phenolic compound in olive oil mill wastewater, have been comparatively degraded by anodic oxidation with electrogenerated H2O2 (AO-H2O2), electro-Fenton (EF) and photoelectro-Fenton (PEF). Trials were performed with a BDD/air-diffusion cell, where oxidizing OH was produced from water discharge at the BDD anode and/or in the solution bulk from Fenton's reaction between cathodically generated H2O2 and added catalytic Fe(2+). The substrate was very slowly removed by AO-H2O2, whereas it was very rapidly abated by EF and PEF, at similar rate in both cases, due to its fast reaction with OH in the bulk. The AO-H2O2 process yielded a slightly lower mineralization than EF, which promoted the accumulation of barely oxidizable products like Fe(III) complexes. In contrast, the fast photolysis of these latter species under irradiation with UVA light in PEF led to an almost total mineralization with 98% total organic carbon decay. The effect of current density and substrate concentration on the performance of all treatments was examined. Several solar PEF (SPEF) trials showed its viability for the treatment of wastewater containing trans-ferulic acid at larger scale. Four primary aromatic products were identified by GC-MS analysis of electrolyzed solutions, and final carboxylic acids like fumaric, acetic and oxalic were detected by ion-exclusion HPLC. A reaction sequence for trans-ferulic acid mineralization involving all the detected products is finally proposed. PMID:26691522

  12. A macromolecular delivery vehicle for protein-based vaccines: Acid-degradable protein-loaded microgels

    PubMed Central

    Murthy, Niren; Xu, Mingcheng; Schuck, Stephany; Kunisawa, Jun; Shastri, Nilabh; Fréchet, Jean M. J.

    2003-01-01

    The development of protein-based vaccines remains a major challenge in the fields of immunology and drug delivery. Although numerous protein antigens have been identified that can generate immunity to infectious pathogens, the development of vaccines based on protein antigens has had limited success because of delivery issues. In this article, an acid-sensitive microgel material is synthesized for the development of protein-based vaccines. The chemical design of these microgels is such that they degrade under the mildly acidic conditions found in the phagosomes of antigen-presenting cells (APCs). The rapid cleavage of the microgels leads to phagosomal disruption through a colloid osmotic mechanism, releasing protein antigens into the APC cytoplasm for class I antigen presentation. Ovalbumin was encapsulated in microgel particles, 200–500 nm in diameter, prepared by inverse emulsion polymerization with a synthesized acid-degradable crosslinker. Ovalbumin is released from the acid-degradable microgels in a pH-dependent manner; for example, microgels containing ovalbumin release 80% of their encapsulated proteins after 5 h at pH 5.0, but release only 10% at pH 7.4. APCs that phagocytosed the acid-degradable microgels containing ovalbumin were capable of activating ovalbumin-specific cytoxic T lymphocytes. The acid-degradable microgels developed in this article should therefore find applications as delivery vehicles for vaccines targeted against viruses and tumors, where the activation of cytoxic T lymphocytes is required for the development of immunity. PMID:12704236

  13. Impact of transverse and longitudinal dispersion on first-order degradation rate constant estimation

    NASA Astrophysics Data System (ADS)

    Stenback, Greg A.; Ong, Say Kee; Rogers, Shane W.; Kjartanson, Bruce H.

    2004-09-01

    A two-dimensional analytical model is employed for estimating the first-order degradation rate constant of hydrophobic organic compounds (HOCs) in contaminated groundwater under steady-state conditions. The model may utilize all aqueous concentration data collected downgradient of a source area, but does not require that any data be collected along the plume centerline. Using a least squares fit of the model to aqueous concentrations measured in monitoring wells, degradation rate constants were estimated at a former manufactured gas plant (FMGP) site in the Midwest U.S. The estimated degradation rate constants are 0.0014, 0.0034, 0.0031, 0.0019, and 0.0053 day -1 for acenaphthene, naphthalene, benzene, ethylbenzene, and toluene, respectively. These estimated rate constants were as low as one-half those estimated with the one-dimensional (centerline) approach of Buscheck and Alcantar [Buscheck, T.E., Alcantar, C.M., 1995. Regression techniques and analytical solutions to demonstrate intrinsic bioremediation. In: Hinchee, R.E., Wilson, J.T., Downey, D.C. (Eds.), Intrinsic Bioremediation, Battelle Press, Columbus, OH, pp. 109-116] which does not account for transverse dispersivity. Varying the transverse and longitudinal dispersivity values over one order of magnitude for toluene data obtained from the FMGP site resulted in nearly a threefold variation in the estimated degradation rate constant—highlighting the importance of reliable estimates of the dispersion coefficients for obtaining reasonable estimates of the degradation rate constants. These results have significant implications for decision making and site management where overestimation of a degradation rate may result in remediation times and bioconversion factors that exceed expectations. For a complex source area or non-steady-state plume, a superposition of analytical models that incorporate longitudinal and transverse dispersion and time may be used at sites where the centerline method would not be

  14. The effect of poly-β-hydroxyalkanoates degradation rate on nitrous oxide production in a denitrifying phosphorus removal system.

    PubMed

    Wei, Yan; Wang, Shuying; Ma, Bin; Li, Xiyao; Yuan, Zhiguo; He, Yuelan; Peng, Yongzhen

    2014-10-01

    Poly-β-hydroxyalkanoates (PHAs) and free nitrous acid (FNA) have been revealed as significant factors causing nitrous oxide (N2O) production in denitrifying phosphorus removal systems. In this study, the effect of PHA degradation rate on N2O production was studied at low FNA levels. N2O production always maintained at approximately 40% of the amount of nitrite reduced independent of the PHA degradation rate. The electrons distributed to nitrite reduction were 1.6 times that to N2O reduction. This indicated that electron competition between these two steps was not affected by the PHA degradation rate. Continuous feed of nitrate was proposed, and demonstrated to reduce N2O accumulation by 75%. While being kept low, a possible compounding effect of a low-level FNA could not be ruled out. The sludge used likely contained both polyphosphate- and glycogen-accumulating organisms, and the results could not be simply attributed to either group of organisms. PMID:25129233

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

    NASA Astrophysics Data System (ADS)

    Zhang, Qian; Zhu, Jinwei; Wang, Ying; Feng, Jiangtao; Yan, Wei; Xu, Hao

    2014-07-01

    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.

  16. In vitro degradation and erosion of degradable, segmented polyurethanes containing an amino acid-based chain extender.

    PubMed

    Skarja, G A; Woodhouse, K A

    2001-01-01

    In vitro degradation and erosion of novel, degradable segmented polyurethanes containing a phenylalanine diester chain extender were investigated by exposing the polymers to buffer. chymotrypsin, and trypsin solutions for up to 28 days. Polyurethane degradation and erosion were monitored by gravimetry, scanning electron microscopy (SEM), and gel permeation chromatography (GPC) and compared to a control polyurethane. Polyurethanes were synthesized using two different soft segments (polycaprolactone diol and polyethylene oxide) of variable molecular weight. Inclusion of the phenylalanine-based chain extender resulted in an increased susceptibility to enzyme-mediated, but not buffer-mediated, erosion in comparison to the control polyurethane. SEM analysis indicated that enzyme-mediated erosion proceeded via a surface-limited mechanism resulting in a progressive removal of material from the surface inwards with time. The magnitude of degradation and erosion was highly variable and was dependent on soft segment type and molecular weight. The range of degradation rates, as well as physicochemical properties, makes these polyurethanes potentially useful for a wide range of biomedical applications. PMID:11718481

  17. Kinetic analysis of acid orange 7 degradation by pulsed discharge plasma combined with activated carbon and the synergistic mechanism exploration.

    PubMed

    Guo, He; Wang, Huijuan; Wu, Qiangshun; Zhou, Guangshun; Yi, Chengwu

    2016-09-01

    The synergistic technique of pulsed discharge plasma (PDP) and activated carbon (AC) was built to investigate the kinetics of acid orange 7 (AO7) degradation under different conditions of AC addition, electrode gap, initial pH value of solution, gas variety and gas flow rate. Emission spectra of OH and O, UV-vis absorption spectra of the AO7 solution and TOC removal were measured to illustrate the synergistic mechanism of the PDP and the AC. The obtained results indicated that the kinetic constant of AO7 degradation increased from 0.00947 min(-1) to 0.01419 min(-1) when 4 g AC was added into the PDP system; AO7 degradation was higher in the case of alkaline solution when oxygen was used as the flow gas in the PDP/AC system, 2 L/min oxygen flow was more favorable for the degradation. Results of the relative emission intensities of OH and O indicated the catalytic effect of the AC on the active species formation as well as the important role of the two radicals for the AO7 degradation. There was no new peaks appeared by the UV-vis analysis of the AO7 solution after 60 min treatment. The highest TOC removal in the PDP/AC system was 30.3%, which was achieved under the condition of 4 L/min air flow rate and 3 initial pH value. PMID:27295438

  18. Degradability of fluorapatite-leucite ceramics in naturally acidic agents.

    PubMed

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

    2010-10-01

    This study was conducted to evaluate the titratable acidity and effect of naturally acidic agents on the surface microhardness, elemental composition, and surface morphology of fluorapatite-leucite ceramics. One hundred and ten ceramic disks (IPS d.SIGN), 12.0 mm in diameter and 2.0 mm in thickness, were fabricated. Before immersion, the baseline data of Vickers microhardness and elemental composition were recorded. Four groups were immersed in acidic agents (citrate buffer solution, green mango juice, and pineapple juice) and deionized water (control) at 37ºC for 168 hours, whereas one group was immersed in 4% acetic acid at 80ºC for 168 hours. After immersion, specimens were evaluated and data were analyzed using one-way repeated ANOVA and Tukey's test (α=0.05). Microhardness values significantly decreased after immersion (p<0.05). In terms of elemental composition, the weight percentages of silicon, potassium, aluminum, and sodium also decreased after immersion (p<0.05). Results of this study showed that fluorapatite-leucite ceramics were affected by long-term immersion in acidic agents. PMID:20827032

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

    PubMed

    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

  20. D-Amino acid metabolism in mammals: biosynthesis, degradation and analytical aspects of the metabolic study.

    PubMed

    Ohide, Hiroko; Miyoshi, Yurika; Maruyama, Rindo; Hamase, Kenji; Konno, Ryuichi

    2011-11-01

    It was believed for long time that d-amino acids are not present in mammals. However, current technological advances and improvements in analytical instruments have enabled studies that now indicate that significant amounts of D-amino acids are present in mammals. The most abundant D-amino acids are D-serine and D-aspartate. D-Serine, which is synthesized by serine racemase and is degraded by D-amino-acid oxidase, is present in the brain and modulates neurotransmission. D-Aspartate, which is synthesized by aspartate racemase and degraded by D-aspartate oxidase, is present in the neuroendocrine and endocrine tissues and testis. It regulates the synthesis and secretion of hormones and spermatogenesis. D-Serine and D-aspartate bind to the N-methyl-D-aspartate (NMDA) subtype of glutamate receptors and function as a coagonist and agonist, respectively. The enzymes that are involved in the synthesis and degradation of these D-amino acids are associated with neural diseases where the NMDA receptors are involved. Knockout mice for serine racemase and D-aspartate oxidase have been generated, and natural mutations in the d-amino-acid oxidase gene are present in mice and rats. These mutant animals display altered behaviors caused by enhanced or decreased NMDA receptor activity. In this article, we review currently available studies on D-amino acid metabolism in mammals and discuss analytical methods used to assay activity of amino acid racemases and D-amino-acid oxidases. PMID:21757409

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

    PubMed

    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

  2. Energetics and kinetics of anaerobic aromatic and fatty acid degradation. Final report

    SciTech Connect

    Michael J. McInerney

    1996-06-24

    The factors that affect the rate and extent of a model aromatic compound, benzoate, in methanogenic environments was studied. Benzoate is degraded to a threshold concentration below which no further substrate degradation occurs. The threshold concentration depended on the substrate concentration and the amount of acetate present. The threshold value was not a function of the kinetic ability of the organism or toxicity of the end products. Rather a minimal Gibb's free energy value may exist where thermodynamic constraints preclude further benzoate degradation. In addition, new bacterial species were isolated and described, that degrade benzoate or reduce iron, cobalt and other metals.

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

    SciTech Connect

    De Windt, Laurent; Devillers, Philippe

    2010-08-15

    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.

  4. The earthworm Aporrectodea caliginosa stimulates abundance and activity of phenoxyalkanoic acid herbicide degraders

    PubMed Central

    Liu, Ya-Jun; Zaprasis, Adrienne; Liu, Shuang-Jiang; Drake, Harold L; Horn, Marcus A

    2011-01-01

    2-Methyl-4-chlorophenoxyacetic acid (MCPA) is a widely used phenoxyalkanoic acid (PAA) herbicide. Earthworms represent the dominant macrofauna and enhance microbial activities in many soils. Thus, the effect of the model earthworm Aporrectodea caliginosa (Oligochaeta, Lumbricidae) on microbial MCPA degradation was assessed in soil columns with agricultural soil. MCPA degradation was quicker in soil with earthworms than without earthworms. Quantitative PCR was inhibition-corrected per nucleic acid extract and indicated that copy numbers of tfdA-like and cadA genes (both encoding oxygenases initiating aerobic PAA degradation) in soil with earthworms were up to three and four times higher than without earthworms, respectively. tfdA-like and 16S rRNA gene transcript copy numbers in soil with earthworms were two and six times higher than without earthworms, respectively. Most probable numbers (MPNs) of MCPA degraders approximated 4 × 105 gdw−1 in soil before incubation and in soil treated without earthworms, whereas MPNs of earthworm-treated soils were approximately 150 × higher. The aerobic capacity of soil to degrade MCPA was higher in earthworm-treated soils than in earthworm-untreated soils. Burrow walls and 0–5 cm depth bulk soil displayed higher capacities to degrade MCPA than did soil from 5–10 cm depth bulk soil, expression of tfdA-like genes in burrow walls was five times higher than in bulk soil and MCPA degraders were abundant in burrow walls (MPNs of 5 × 107 gdw−1). The collective data indicate that earthworms stimulate abundance and activity of MCPA degraders endogenous to soil by their burrowing activities and might thus be advantageous for enhancing PAA degradation in soil. PMID:20740027

  5. GFP Reporter Screens for the Engineering of Amino Acid Degrading Enzymes from Libraries Expressed in Bacteria

    PubMed Central

    Paley, Olga; Agnello, Giulia; Cantor, Jason; Yoo, Tae Hyun; Georgiou, George; Stone, Everett

    2014-01-01

    There is significant interest in engineering human amino acid degrading enzymes as non-immunogenic chemotherapeutic agents. We describe a high-throughput fluorescence activated cell sorting (FACS) assay for detecting the catalytic activity of amino acid degrading enzymes in bacteria, at the single cell level. This assay relies on coupling the synthesis of the GFP reporter to the catalytic activity of the desired amino acid degrading enzyme in an appropriate E. coli genetic background. The method described here allows facile screening of much larger libraries (106–107) than was previously possible. We demonstrate the application of this technique in the screening of libraries of bacterial and human asparaginases and also for the catalytic optimization of an engineered human methionine gamma lyase. PMID:23423887

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

    PubMed

    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

  7. Dense fouling in acid transfer pipelines by an acidophilic rubber degrading fungus.

    PubMed

    Joshi, M Hiren; Balamurugan, P; Venugopalan, V P; Rao, T S

    2011-07-01

    An unique case of dense fouling by an acidophilic, hard rubber (polymerized rubber) degrading fungus in the acid transfer pipelines of a boron enrichment plant located at Kalpakkam, India is reported. In spite of a highly adverse environment for survival (pH 1.5, no dissolved nutrients), the fungus thrived and clogged the pipeline used for transferring 0.1N hydrochloric acid (HCl). Detailed investigations were carried out to isolate and identify the fungus and examine the nutrient source for such profuse growth inside the system. Microscopic observation showed the presence of a thick filamentous fungal biomass. Molecular characterization by 18S rRNA gene sequencing showed 98% similarity of the isolate with the acidophilic fungus Bispora sp. In laboratory studies the fungus showed luxuriant growth (specific growth rate of 13 mg day⁻¹) when scrapings of the hard rubber were used as the sole source of carbon. Scanning electron microscopy revealed extensive incursion of the fungus into the hard rubber matrix. In the laboratory, fungal growth was completely inhibited by the antifungal agent sodium omadine. The study illustrates an interesting example of biofouling under extreme conditions and demonstrates that organisms can physiologically adapt to grow under unfavourable conditions, provided that a nutrient source is available and competition is low. The use of this fungal strain in biodegradation and in development of environmentally compatible processes for disposal of rubber wastes is envisaged. PMID:21722066

  8. [Analysis of alkaline CuO degradation products of acid detergent fiber from tobacco leaves by using liquid chromatography].

    PubMed

    Hao, Weiqiang; Wang, Leijun; Wu, Shun; Yue, Bangyi; Chen, Qiang; Zhang, Peipei

    2015-07-01

    The acid detergent fiber (ADF) from tobacco leaves was obtained by treating the sample with petroleum ether-ethanol (6:4, v/v), 30 g/L sodium dodecylsulfate and 0.5 mol/L sulphuric acid containing 20 g/L hexadecyl trimethyl ammonium bromide successively. The ADF was degraded by the alkaline CuO oxidation procedure. In this work, six samples of ADF degradation products from tobacco leaves were prepared. The samples were analyzed by using gradient liquid chromatography (LC) where an Ultimate XB C18 column was used as stationary phase, with a mixture of methanol and water as mobile phase, at a column temperature of 35 °C and a flow rate of 0.8 mL/min. Dual wavelengths of 280 nm and 320 nm were chosen for the detection. It was found that there were four characteristic peaks for the ADF degradation products. By taking these peaks as research object, the optimum time for the degradation was found to be 5 h and the sample solution could be kept stable within 7 days. The established method may provide a new approach for the studies of the differences between lignin composition in different tobacco leaves and the relationship between lignin content and the smoking quality of tobacco leaves. PMID:26672209

  9. Screening of Indigenous Oxalate Degrading Lactic Acid Bacteria from Human Faeces and South Indian Fermented Foods: Assessment of Probiotic Potential

    PubMed Central

    Kavitha, Murugan; Selvi, M. S.; Selvam, Govindan Sadasivam

    2014-01-01

    Lactic acid bacteria (LAB) have the potential to degrade intestinal oxalate and this is increasingly being studied as a promising probiotic solution to manage kidney stone disease. In this study, oxalate degrading LAB were isolated from human faeces and south Indian fermented foods, subsequently assessed for potential probiotic property in vitro and in vivo. Based on preliminary characteristics, 251 out of 673 bacterial isolates were identified as LAB. A total of 17 strains were found to degrade oxalate significantly between 40.38% and 62.90% and were subjected to acid and bile tolerance test. Among them, nine strains exhibited considerable tolerance up to pH 3.0 and at 0.3% bile. These were identified as Lactobacillus fermentum and Lactobacillus salivarius using 16S rDNA sequencing. Three strains, Lactobacillus fermentum TY5, Lactobacillus fermentum AB1, and Lactobacillus salivarius AB11, exhibited good adhesion to HT-29 cells and strong antimicrobial activity. They also conferred resistance to kanamycin, rifampicin, and ampicillin, but were sensitive to chloramphenicol and erythromycin. The faecal recovery rate of these strains was observed as 15.16% (TY5), 6.71% (AB1), and 9.3% (AB11) which indicates the colonization ability. In conclusion, three efficient oxalate degrading LAB were identified and their safety assessments suggest that they may serve as good probiotic candidates for preventing hyperoxaluria. PMID:24723820

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

    PubMed

    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 <0.01% loss of sucrose in all reactions. The optimal values of the process parameters for a 200 mg/L HCA mixture in water (pH 4.73, 25.15 °C) and sucrose solution (13 mass %, pH 5.39, 35.98 °C) were 77% and 57%, respectively. Regression 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

  11. Effect of application rate on fumigant degradation in five agricultural soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fumigants continue to be used in soil disinfestation for many high value crops. There is a significant knowledge gap on how fumigant concentration in soil impacts fumigant dissipation and determination of the most efficient rate. The aim of this study was to determine the degradation characteristics...

  12. Spatial Moment Equations for a Groundwater Plume with Degradation and Rate-Limited Sorption

    EPA Science Inventory

    In this note, we analytically derive the solution for the spatial moments of groundwater solute concentration distributions simulated by a one-dimensional model that assumes advective-dispersive transport with first-order degradation and rate-limited sorption. Sorption kinetics...

  13. High-rate two-phase process for the anaerobic degradation of cellulose, employing rumen microorganisms for an efficient acidogenesis

    SciTech Connect

    Gijzen, H.J.; Zwart, K.B.; Verhagen, F.J.M.; Vogels, G.D.

    1988-04-05

    A novel two-stage anaerobic process for the microbial conversion of cellulose into biogas has been developed. In the first phase, a mixed population of rumen bacteria and ciliates was used in the hydrolysis and fermentation of cellulose. The volatile fatty acids (VFA) produced in this acidogenic reactor were subsequently converted into biogas in a UASB-type methanogenic reactor. A stepwise increase of the loading rate from 11.9 to 25.8 g volatile solids/L reactor volume/day (g VS/L/day) did not affect the degradation efficiency in the acidogenic reactor, whereas the methanogenic reactor appeared to be overloaded at the highest loading rate. Cellulose digestion was almost complete at all loading rates applied. The two-stage anaerobic process was also tested with a closed fluid circuit. In this instance total methane production was 0.438 L CH/sub 4//g VS added, which is equivalent to 98% of the theoretical value. The application of rumen microorganisms in combination with a high-rate methane reactor is proposed as a means of efficient anaerobic degradation of cellulosic residues to methane. Because this newly developed two-phase system is based on processes and microorganisms from the ruminant, it will be referred to as Rumen Derived Anaerobic Digestion (RUDAD)-process.

  14. Effects of dry method esterification of starch on the degradation characteristics of starch/polylactic acid composites.

    PubMed

    Zuo, Ying Feng; Gu, Jiyou; Qiao, Zhibang; Tan, Haiyan; Cao, Jun; Zhang, Yanhua

    2015-01-01

    Maleic anhydride esterified corn starch was prepared by dry method. Esterified starch/polylactic acid (PLA) biodegradable composite was produced via melt extrusion method with blending maleic anhydride esterified corn starch and PLA. The influence of the dry method esterification of starch on the degradation characteristics of starch/PLA composites was investigated by the natural aging degradation which was soil burial method. Test results of mass loss rate showed that the first 30 days of degradation was mainly starch degradation, and the degradation rate of esterified starch/PLA (ES/PLA) was slower than that of native starch/PLA (NS/PLA). Therefore, the damage degree of ES/PLA on the surface and inside was smaller than that of NS/PLA, and the infrared absorption peak intensities of C-O, C=O and C-H were stronger than that of NS/PLA. With the increasing time of soil burial degradation, the damage degree of NS/PLA and ES/PLA on the exterior and interior were gradually increased, whereas the infrared absorption peak intensities of C-O, C=O and C-H were gradually decreased. The XRD diffraction peak intensity of PLA in composites showed an increased trend at first which was then followed by a decreased one along with the increasing time of soil burial degradation, indicating that the degradation of amorphous regions of PLA was earlier than its crystalline regions. When the soil burial time was the same, the diffraction peak intensity of PLA in ES/PLA was stronger than that of NS/PLA. If the degradation time was the same, T0, Ti and residual rate of thermal decomposition of NS/PLA were larger than those of ES/PLA. The tensile strength and bending strength of composites were decreased gradually with soil burial time increasing. Both the tensile strength and bending strength of ES/PLA were stronger than those of NS/PLA. PMID:25192854

  15. ESTIMATION OF CARBOXYLIC ACID ESTER HYDROLYSIS RATE CONSTANTS

    EPA Science Inventory

    SPARC chemical reactivity models were extended to calculate hydrolysis rate constants for carboxylic acid esters from molecular structure. The energy differences between the initial state and the transition state for a molecule of interest are factored into internal and external...

  16. Heart Rate Response and Lactic Acid Concentration in Squash Players.

    ERIC Educational Resources Information Center

    Beaudin, Paula; And Others

    1978-01-01

    It was concluded that playing squash is an activity that results in heart rate responses of sufficient intensity to elicit aerobic training effects without producing high lactic acid concentration in the blood. (MM)

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

    PubMed

    Wang, Xiaoyu; Chen, Meili; Xiao, Jingfa; Hao, Lirui; Crowley, David E; Zhang, Zhewen; Yu, Jun; Huang, Ning; Huo, Mingxin; Wu, Jiayan

    2015-01-01

    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. PMID:26301592

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

    PubMed Central

    Xiao, Jingfa; Hao, Lirui; Crowley, David E.; Zhang, Zhewen; Yu, Jun; Huang, Ning; Huo, Mingxin; Wu, Jiayan

    2015-01-01

    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. PMID:26301592

  19. Enzymes involved in a novel anaerobic cyclohexane carboxylic acid degradation pathway.

    PubMed

    Kung, Johannes W; Meier, Anne-Katrin; Mergelsberg, Mario; Boll, Matthias

    2014-10-01

    The anaerobic degradation of cyclohexane carboxylic acid (CHC) has so far been studied only in Rhodopseudomonas palustris, in which CHC is activated to cyclohexanoyl coenzyme A (cyclohexanoyl-CoA [CHCoA]) and then dehydrogenated to cyclohex-1-ene-1-carboxyl-CoA (CHeneCoA). This intermediate is further degraded by reactions of the R. palustris-specific benzoyl-CoA degradation pathway of aromatic compounds. However, CHeneCoA is not an intermediate in the degradation of aromatic compounds in all other known anaerobic bacteria; consequently, degradation of CHC was mostly unknown in anaerobic bacteria. We identified a previously unknown CHC degradation pathway in the Fe(III)-reducing Geobacter metallireducens by determining the following CHC-induced in vitro activities: (i) the activation of CHC to CHCoA by a succinyl-CoA:CHC CoA transferase, (ii) the 1,2-dehydrogenation of CHCoA to CHeneCoA by CHCoA dehydrogenase, and (iii) the unusual 1,4-dehydrogenation of CHeneCoA to cyclohex-1,5-diene-1-carboxyl-CoA. This last represents a previously unknown joint intermediate of the CHC and aromatic compound degradation pathway in bacteria other than R. palustris. The enzymes catalyzing the three reactions were purified and characterized as specific enzymes after heterologous expression of the encoding genes. Quantitative reverse transcription-PCR revealed that expression of these genes was highly induced during growth with CHC but not with benzoate. The newly identified CHC degradation pathway is suggested to be present in nearly all CHC-degrading anaerobic bacteria, including denitrifying, Fe(III)-reducing, sulfate-reducing, and fermenting bacteria. Remarkably, all three CHC degradation pathways always link CHC catabolism to the catabolic pathways of aromatic compounds. We propose that the capacity to use CHC as a carbon source evolved from already-existing aromatic compound degradation pathways. PMID:25112478

  20. SURFACE DEGRADATION OF COMPOSITE RESINS BY ACIDIC MEDICINES AND pH-CYCLING

    PubMed Central

    Valinoti, Ana Carolina; Neves, Beatriz Gonçalves; da Silva, Eduardo Moreira; Maia, Lucianne Cople

    2008-01-01

    This study evaluated the effects of acidic medicines (Dimetapp® and Claritin®), under pH-cycling conditions, on the surface degradation of four composite resins (microhybrid: TPH, Concept, Opallis and Nanofilled: Supreme). Thirty disc-shaped specimens (Ø = 5.0 mm / thickness = 2.0 mm) of each composite were randomly assigned to 3 groups (n = 10): a control and two experimental groups, according to the acidic medicines evaluated. The specimens were finished and polished with aluminum oxide discs, and the surface roughness was measured by using a profilometer. After the specimens were submitted to a pH-cycling regimen and immersion in acidic medicines for 12 days, the surface roughness was measured again. Two specimens for each material and group were analyzed by scanning electron microscopy (SEM) before and after pH-cycling. Data were analyzed by the Student's-t test, ANOVA, Duncan's multiple range test and paired t-test (α=0.05). Significant increase in roughness was found only for TPH in the control group and TPH and Supreme immersed in Claritin® (p<0.05). SEM analyses showed that the 4 composite resins underwent erosion and surface degradation after being subjected to the experimental conditions. In conclusion, although the roughness was slightly affected, the pH-cycling and acidic medicines caused surface degradation of the composite resins evaluated. Titratable acidity seemed to play a more crucial role on surface degradation of composite resins than pH. PMID:19089257

  1. Comparative Genomics of Syntrophic Branched-Chain Fatty Acid Degrading Bacteria

    PubMed Central

    Narihiro, Takashi; Nobu, Masaru K.; Tamaki, Hideyuki; Kamagata, Yoichi; Sekiguchi, Yuji; Liu, Wen-Tso

    2016-01-01

    The syntrophic degradation of branched-chain fatty acids (BCFAs) such as 2-methylbutyrate and isobutyrate is an essential step in the production of methane from proteins/amino acids in anaerobic ecosystems. While a few syntrophic BCFA-degrading bacteria have been isolated, their metabolic pathways in BCFA and short-chain fatty acid (SCFA) degradation as well as energy conservation systems remain unclear. In an attempt to identify these pathways, we herein performed comparative genomics of three syntrophic bacteria: 2-methylbutyrate-degrading “Syntrophomonas wolfei subsp. methylbutyratica” strain JCM 14075T (=4J5T), isobutyrate-degrading Syntrophothermus lipocalidus strain TGB-C1T, and non-BCFA-metabolizing S. wolfei subsp. wolfei strain GöttingenT. We demonstrated that 4J5 and TGB-C1 both encode multiple genes/gene clusters involved in β-oxidation, as observed in the Göttingen genome, which has multiple copies of genes associated with butyrate degradation. The 4J5 genome possesses phylogenetically distinct β-oxidation genes, which may be involved in 2-methylbutyrate degradation. In addition, these Syntrophomonadaceae strains harbor various hydrogen/formate generation systems (i.e., electron-bifurcating hydrogenase, formate dehydrogenase, and membrane-bound hydrogenase) and energy-conserving electron transport systems, including electron transfer flavoprotein (ETF)-linked acyl-CoA dehydrogenase, ETF-linked iron-sulfur binding reductase, ETF dehydrogenase (FixABCX), and flavin oxidoreductase-heterodisulfide reductase (Flox-Hdr). Unexpectedly, the TGB-C1 genome encodes a nitrogenase complex, which may function as an alternative H2 generation mechanism. These results suggest that the BCFA-degrading syntrophic strains 4J5 and TGB-C1 possess specific β-oxidation-related enzymes for BCFA oxidation as well as appropriate energy conservation systems to perform thermodynamically unfavorable syntrophic metabolism. PMID:27431485

  2. Kinetics study on the degradation of a model naphthenic acid by ethylenediamine-N,N'-disuccinic acid-modified Fenton process.

    PubMed

    Zhang, Ying; Klamerth, Nikolaus; Messele, Selamawit Ashagre; Chelme-Ayala, Pamela; Gamal El-Din, Mohamed

    2016-11-15

    Naphthenic acids (NAs) are reported to be the main species responsible for the oil sands process-affected water (OSPW) toxicity. In this study, the degradation of cyclohexanoic acid (CHA) as a model compound for NAs by an ethylenediamine-N,N'-disuccinic acid (EDDS)-modified Fenton process was investigated at pH 8. Optimum dose for Fe-EDDS (EDDS:Fe=2:1) was 0.45mM, and 2.94mM for hydrogen peroxide (H2O2). The time profiles of the main species in the process were studied, including CHA, H2O2, Fe(II), total Fe, and Fe-EDDS (in the main form of Fe(III)EDDS). The second-order rate constant between EDDS and hydroxyl radical (OH) at pH 8 was obtained as 2.48±0.43×10(9)M(-1)s(-1). OH was proved to be the main species responsible for the CHA degradation, while superoxide radical (O2(-)) played a minor role. The consecutive addition of H2O2 and Fe-EDDS led to a higher removal of CHA compared to that achieved by adding the reagents at a time. The half-wave potential of Fe(III/II)EDDS was measured at pH 7-9. The EDDS-modified Fenton process is a promising alternative to degrade NAs. PMID:27442987

  3. OH-radical induced degradation of hydroxybenzoic- and hydroxycinnamic acids and formation of aromatic products—A gamma radiolysis study

    NASA Astrophysics Data System (ADS)

    Krimmel, Birgit; Swoboda, Friederike; Solar, Sonja; Reznicek, Gottfried

    2010-12-01

    The OH-radical induced degradation of hydroxybenzoic acids (HBA), hydroxycinnamic acids (HCiA) and methoxylated derivatives, as well as of chlorogenic acid and rosmarinic acid was studied by gamma radiolysis in aerated aqueous solutions. Primary aromatic products resulting from an OH-radical attachment to the ring (hydroxylation), to the position occupied by the methoxyl group (replacement -OCH 3 by -OH) as well as to the propenoic acid side chain of the cinnamic acids (benzaldehyde formations) were analysed by HPLC-UV and LC-ESI-MS. A comparison of the extent of these processes is given for 3,4-dihydroxybenzoic acid, vanillic acid, isovanillic acid, syringic acid, cinnamic acid, 4-hydroxycinnamic acid, caffeic acid, ferulic acid, isoferulic acid, chlorogenic acid, and rosmarinic acid. For all cinnamic acids and derivatives benzaldehydes were significant oxidation products. With the release of caffeic acid from chlorogenic acid the cleavage of a phenolic glycoside could be demonstrated. Reaction mechanisms are discussed.

  4. Retrospective analysis for the identification of 4-aminocarminic acid photo-degradation products in beverages.

    PubMed

    Gosetti, Fabio; Chiuminatto, Ugo; Mastroianni, Rita; Mazzucco, Eleonora; Manfredi, Marcello; Marengo, Emilio

    2015-01-01

    This article deals with the identification of the photo-degradation products of 4-aminocarminic acid potentially present in commercial beverages. Sixteen beverages of different composition but all containing the E120 dye were previously analysed by ultra-high-performance liquid chromatography (UHPLC) coupled with quadrupole-time of flight mass spectrometry to identify the common degradation products of the E120 dye. Since it is plausible to find unauthorised 4-aminocarminic acid in beverages which report generic E120 dye on the label, retrospective analysis was employed here not only to search for the possible presence of 4-aminocarminic acid but also to investigate the potential formation of photo-degradation products derived from this compound. For this purpose, a statistical approach based on Student's t-test was used to compare the degraded beverages containing 4-aminocarminic acid with all the others. Five degradation products were identified and their structures were elucidated on the basis of the high-accuracy and high-resolution of mass and mass/mass spectra. The toxicity of the degradation products was evaluated through the Ames Salmonella/microsome mutagenicity assay. No evidence of mutagenicity was obtained for the beverages subjected or not to irradiation, whereas a toxic effect of the 4-aminocarminic acid standard solution already at 100.0 µg l(-1) was found. This leads, once again, to the conclusion that the toxicity study must be carried out on the beverages in order to take into account of all the possible masking/protection interactions among the ingredients. PMID:25562586

  5. Effect of dairy manure rate and the stabilization time of amended soils on atrazine degradation.

    PubMed

    Aguilera, Paula; Briceño, Gabriela; Candia, Maribel; Mora, Maria de la Luz; Demanet, Rolando; Palma, Graciela

    2009-10-01

    The application rate of liquid cow manure (LCM) in the field and the stabilization time of amended soils before application of pre-plant herbicides are factors that determine their efficiency. This study includes evaluation of residual atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) in soil and amended soils with equivalent rate of 100,000; 200,000; and 300,000 L ha(-1) of LCM and the effect of pre-incubation time of amended soils on atrazine degradation. The study was carried out under controlled conditions using an Andisol with previous historical application of atrazine. The respiratory activity and fluorescein diacetate (FDA) studies indicated that the time necessary for stabilization of amended soils is over 20-30 d. During the measurement of respiratory and FDA activity, no significant differences were observed when atrazine was applied. The half-life of atrazine ranged from 5 to 8d and the relative distribution of degradation products seem to be affected by the application of LCM. The pre-incubation time of amended soil and LCM dose would not affect atrazine degradation rate, when the soil has a history of herbicide application. However, repeated applications of LCM in a long period of time could change the soil pH and increase the content of dissolved organic carbon (DOC) which could further contribute to a faster degradation of atrazine. Both effects would reduce the effectiveness of atrazine in weed control. PMID:19744695

  6. Isolation and characterization of Bradyrhizobium sp. 224 capable of degrading sulfanilic acid.

    PubMed

    Hayase, Nobuki; Fujikawa, Yui; Nakagawa, Katsuhiko; Ushio, Kazutoshi

    2016-08-01

    A bacterial strain (strain 224), which has the ability to utilize sulfanilic acid as a sole source of carbon, was isolated from soil. 16S rRNA gene sequence obtained from strain 224 exhibited 100% identical to that of species in the genus Bradyrhizobium. Strain 224 degraded 4.7 mM of sulfanilic acid and released almost the same molar concentration of sulfate ion. PMID:27108596

  7. Dose rate effects in radiation degradation of polymer-based cable materials

    NASA Astrophysics Data System (ADS)

    Plaček, V.; Bartoníček, B.; Hnát, V.; Otáhal, B.

    2003-08-01

    Cable ageing under the nuclear power plant (NPP) conditions must be effectively managed to ensure that the required plant safety and reliability are maintained throughout the plant service life. Ionizing radiation is one of the main stressors causing age-related degradation of polymer-based cable materials in air. For a given absorbed dose, radiation-induced damage to a polymer in air environment usually depends on the dose rate of the exposure. In this work, the effect of dose rate on the degradation rate has been studied. Three types of NPP cables (with jacket/insulation combinations PVC/PVC, PVC/PE, XPE/XPE) were irradiated at room temperature using 60Co gamma ray source at average dose rates of 7, 30 and 100 Gy/h with the doses up to 590 kGy. The irradiated samples have been tested for their mechanical properties, thermo-oxidative stability (using differential scanning calorimetry, DSC), and density. In the case of PVC and PE samples, the tested properties have shown evident dose rate effects, while the XPE material has shown no noticeable ones. The values of elongation at break and the thermo-oxidative stability decrease with the advanced degradation, density tends to increase with the absorbed dose. For XPE samples this effect can be partially explained by the increase of crystallinity. It was tested by the DSC determination of the crystalline phase amount.

  8. The sonochemical degradation of azobenzene and related azo dyes: Rate enhancements via Fenton's reactions

    SciTech Connect

    Joseph, J.M.; Destaillats, H.; Hung, H.M.; Hoffmann, M.R.

    2000-01-20

    The sonochemical degradation of aqueous solutions of azobenzene and related azo dyes (methyl orange, o-methyl red, and p-methyl red) was performed at 500 kHz and 50 W, under air, O{sub 2}, or Ar saturation at 288 K. Reaction products and intermediates were identified by HPLC-ES-MS. Total organic carbon (TOC) was also determined as a function of reaction time. The authors propose a reaction mechanism based on the observed species and the extent and rate of TOC depletion. The effects of the dye structures and of the background gas on the sonochemical bleaching rates were also investigated. The reaction rates for o-methyl red were approximately 30--40% faster than those for the other compounds. Saturating with Ar instead of air or O{sub 2} increased the pseudo first-order rate constants for the degradation by 10%. The acceleration of the sonochemical bleaching and the mineralization process upon addition of Fe(II) was also investigated in Ar-saturated methyl orange solutions. A 3-fold increase in the reaction rate was observed at optimal Fe(II) concentrations. This kinetic effect is quantitatively accounted for by a simple kinetic model based on the reaction of Fe(II) with sonochemically produced H{sub 2}O{sub 2} (Fenton's reaction). This latter effect illustrates a simple way of achieving a substantial improvement in the efficiency of sonochemical degradation reactions.

  9. Degradation kinetic modelling of ascorbic acid and colour intensity in pasteurised blood orange juice during storage.

    PubMed

    Remini, Hocine; Mertz, Christian; Belbahi, Amine; Achir, Nawel; Dornier, Manuel; Madani, Khodir

    2015-04-15

    The stability of ascorbic acid and colour intensity in pasteurised blood orange juice (Citrus sinensis [L.] Osbeck) during one month of storage was investigated at 4-37 °C. The effects of ascorbic acid fortification (at 100, 200 mg L(-1)) and deaeration, temperature/time storage on the kinetic behaviour were determined. Ascorbic acid was monitored by HPLC-DAD and colour intensity by spectrophotometric measurements. Degradation kinetics were best fitted by first-order reaction models for both ascorbic acid and colour intensity. Three models (Arrhenius, Eyring and Ball) were used to assess the temperature-dependent degradation. Following the Arrhenius model, activation energies were ranged from 51 to 135 kJ mol(-1) for ascorbic acid and from 49 to 99 kJ mol(-1) for colour intensity. The effect of storage temperature and deaeration are the most influent factors on kinetics degradation, while the fortification revealed no significant effect on ascorbic acid content and colour intensity. PMID:25466074

  10. Atmospheric aqueous-phase photoreactivity: correlation between the hydroxyl radical photoformation and pesticide degradation rate in atmospherically relevant waters.

    PubMed

    Charbouillot, Tiffany; Brigante, Marcello; Deguillaume, Laurent; Mailhot, Gilles

    2012-01-01

    In the present study, we investigated the correlation between the hydroxyl radical formation rate (R(˙OH) ) and the degradation of a pesticide (mesotrione) in synthetic cloud water solutions and in two real atmospheric cloud waters collected at the top of puy de Dôme station (France). Using terephthalic acid as the hydroxyl radical chemical probe, we established the linear correlation between the photogenerated hydroxyl radical under polychromatic wavelengths and the pesticide degradation rate: (M s(-1)) = (1.61 ± 0.15) × 10(-1) (M s(-1)). Moreover, the formation rate of hydroxyl radical in two natural cloud waters was estimated considering H(2)O(2) and NO(3)(-) and the difference between the predicted values and those experimentally obtained could be attributed to the presence of other photochemical sources: iron-complexes and total organic matter. The organic constituents could play a dual role of sources and scavengers of photoformed hydroxyl radicals in the aqueous phase. PMID:21988772

  11. Acid-catalyzed hydrolysis of BMS-582664: degradation product identification and mechanism elucidation.

    PubMed

    Zhao, Fang; Derbin, George; Miller, Scott; Badawy, Sherif; Hussain, Munir

    2012-09-01

    BMS-582664 is an investigational drug intended for cancer treatment through oral administration. The preformulation studies revealed two unexpected degradation products under acidic conditions by reversed-phase high-performance liquid chromatography with ultraviolet detection. Additional liquid chromatography-mass spectrometry results suggested that these were cleavage (hydrolysis) products of a diaryl ether. To further understand the degradation mechanism, the reaction was carried out in (18) O-labeled water. The (18) O was found to be incorporated in only one of the two hydrolysis products. The results suggest that the corresponding α carbon in the heterocycle was unusually eletrophilic in acidic conditions probably because of the protonation of the neighboring nitrogen. This led to the selective attack by water and the consequent hydrolysis products. The study provides a new example of hydrolytic degradation of pharmaceutical compounds, and the reaction center is an aromatic heterocyclic carbon with an aryloxy substitution. PMID:22189636

  12. Mechanistic Study of the Acid Degradation of Lignin Model Compounds

    SciTech Connect

    Sturgeon, M.; Kim, S.; Chmely, S. C.; Foust, T. D.; Beckham, G. T.

    2012-01-01

    Lignin is a major constituent of biomass, which remains underutilized in selective biomass conversion strategies to renewable fuels and chemicals. Here we are interested in understanding the mechanisms related to the acid deconstruction of lignin with a combined theoretical and experimental approach. Two model dimers with a b-O-4 aryl ether linkage (2-phenoxy-1-phenethanol and 2-phenoxy-1-phenyl-1,3 propanediol) and model dimmers with an a-O-4 aryl ether linkage were synthesized and deconstructed in H2SO4. The major products of the acidolysis of the b-O-4 compounds consisted of phenol and two aldehydes, phenylacetaldehyde and benzaldehyde. Quantum mechanical calculations were employed to elucidate possible deconstruction mechanisms with transition state theory. To confirm proposed mechanisms several possible intermediates were studied under similar acidolysis conditions. Although the resonance time for cleavage was on the order several hours, we have shown that the cleavage of the aryl ether linkage affords phenol and aldehydes. We would next like to utilize our mechanism of aryl ether cleavage in actual lignin.

  13. Nitrite attenuated hypochlorous acid-mediated heme degradation in hemoglobin.

    PubMed

    Lu, Naihao; Li, Jiayu; Ren, Xiaoming; Tian, Rong; Peng, Yi-Yuan

    2015-08-01

    Hypochlorous acid (HOCl) is elevated in many inflammatory diseases and causes the accumulation of free iron. Through the Fenton reaction, free iron has the ability to generate free radicals and subsequently is toxic. Recent studies have demonstrated that HOCl participates in heme destruction of hemoglobin (Hb) and free iron release. In this study, it was showed that nitrite (NO2(-)) could prevent HOCl-mediated Hb heme destruction and free iron release. Also, NO2(-) prevented HOCl-mediated loss of Hb peroxidase activity. After the NO2(-)/HOCl treatment, Tyr 42 in α-chain was found to be nitrated in Hb, attenuating the electron transferring abilities of phenolic compounds. The protective effects of NO2(-) on HOCl-induced heme destruction were attributed to its reduction of ferryl Hb and/or direct scavenging of HOCl. Therefore, NO2(-) could show protective effects in some inflammatory diseases by preventing HOCl-mediated heme destruction of hemoproteins and free iron release. PMID:26051522

  14. Competitive kinetics versus stopped flow method for determining the degradation rate constants of steroids by ozonation.

    PubMed

    López-López, Alberto; Flores-Payán, Valentín; León-Becerril, Elizabeth; Hernández-Mena, Leonel; Vallejo-Rodríguez, Ramiro

    2016-01-01

    Steroids are classified as endocrine disrupting chemicals; they are persistent with low biodegradability and are hardly degraded by conventional methods. Ozonation process has been effective for steroids degradation and the determination of the kinetics is a fundamental aspect for the design and operation of the reactor. This study assessed two methods: competitive kinetics and stopped flow, for determining the degradation kinetics of two steroids, estradiol (E2) and ethinylestradiol (EE2) in spiked water. Experiments were performed at pH 6, 21 °C, and using tertbutyl alcohol as scavenger of hydroxyl radicals; competitive kinetics method used sodium phenolate as reference compound. For the stopped flow, the experiments were performed in a BioLogic SFM-3000/S equipment. For both methods, the second order rate constants were in the order of 10(6) and 10(5) M(-1) s(-1) for E2 and EE2 respectively. The competitive kinetics can be applied with assurance and reliability but needing an additional analysis method to measure the residual concentrations. Stopped flow method allows the evaluation of the degradation kinetics in milliseconds and avoids the use of additional analytical methodologies; this method allows determining the reaction times on line. The methods are applicable for degradation of other emerging contaminants or other steroids and could be applied in water treatment at industrial level. Finally, it is important to consider the resources available to implement the most appropriate method, either competitive kinetics or the stopped-flow method. PMID:27478722

  15. Study on the enzymatic degradation of PBS and its alcohol acid modified copolymer.

    PubMed

    Ding, Mingliang; Zhang, Min; Yang, Jinming; Qiu, Jian-hui

    2012-02-01

    Enzymatic hydrolytic degradation of polybutylene succinate (PBS), poly(polybutylenesuccinate-co-1,4-cyclohexane dimethanol) (PBS/CHDM) and poly(polybutylene succinate-co-diglycolic acid) (PBS/DGA) in mixed solvent of tetrahydrofuran (THF) and toluene was examined. Lipase was used as catalyst to degrade polymers with molecular weight of more than 100,000, and the molecular weight of products ranged from hundreds to thousands. Thermal decomposition temperatures of all products were below 250°C. The degradation products of both PBS/CHDM and PBS/DGA showed two melting points at about 85 and 99°C. Mass spectrometry (MS) was employed to obtain the molecular weight of oligomers extracted from the products, which proved to be low-polyesters with the molecular weight of less 1,000. The butanediol (BDO) monomer was found in PBS/CHDM degradation product for the first time. PMID:21732135

  16. Degradation of ferric chelate of ethylenediaminetetraacetic acid by bacterium isolated from deep-sea stalked barnacle.

    PubMed

    Imada, Chiaki; Harada, Yohei; Kobayashi, Takeshi; Hamada-Sato, Naoko; Watanabe, Etsuo

    2005-01-01

    Twenty strains of marine bacteria that degrade ferric chelate of ethylenediaminetetraacetic acid (Fe-EDTA) were isolated from among 117 strains collected from a marine environment. Among them strain 02-N-2, which was isolated from stalked barnacle collected from the deep sea in the Indian Ocean, had the highest Fe-EDTA degradation ability and was selected for further study. The strain showed high Fe-EDTA degradation ability at different seawater concentrations. In addition, the intact cells of this strain had the ability to degrade such metal-EDTAs as Ca, Cu, and Mg. The strain was an aerobic, gram-variable, rod-shaped organism. The results of various taxonomic studies revealed that the strain had significant similarity to Bacillus jeotgali JCM 10885(T), which was isolated from a Korean traditional fermented seafood, Jeotgal. PMID:15747087

  17. DEGRADATION OF DEOXYRIBONUCLEIC ACID AND ALTERATION OF NUCLEIC ACID METABOLISM IN SUSPENSION CULTURES OF L-M CELLS INFECTED WITH EQUINE ABORTION VIRUS

    PubMed Central

    Randall, Charles C.; Walker, Barbara M.

    1963-01-01

    Randall, Charles C. (University of Mississippi School of Medicine, Jackson) and Barbara M. Walker. Degradation of deoxyribonucleic acid and alteration of nucleic acid metabolism in suspension cultures of L-M cells infected with equine abortion virus. J. Bacteriol. 86:138–146. 1963.—Metabolic alterations in log-phase suspension cultures infected with equine abortion virus (EAV) were determined in L-M cells simultaneously labeled or prelabeled with H3- or C14-thymidine. Although infection produced an early stimulation of the uptake of labeled thymidine (TdR) into the acid-soluble fraction of concurrently labeled cells, incorporation of the isotope into deoxyribonucleic acid (DNA) was progressively inhibited. The specific activity of infected-cell DNA was 48% of the control at 24 hr. The rate of incorporation of isotope from 12 to 24 hr was 43 and 13 counts per min per μg of DNA per hr for control and infected cultures, respectively. Owing to degradation of DNA, synthesis could not be accurately determined with the concurrently labeled cells. On the other hand, with prelabeled cells, quantitative isotopic methods could be used to determine the amount of DNA synthesized by measuring dilution of specific activity, even though infection triggered degradation of DNA into acid-soluble components. With this method, the DNA synthesized in infected cultures for 24 hr was approximately five times greater than the slight net increase determined by the diphenylamine reaction. The specific activity of infected-cell DNA decreased and then remained fixed after 24 hr, with 53% of the radioactivity appearing in the medium by 48 hr. No radioactive CO2 was detected as a consequence of DNA degradation. Infected cells lost ribonucleic acid (RNA) as well as DNA; RNA and DNA were reduced by 64 and 50%, respectively, at 48 hr. The degradation of DNA was effectively inhibited by chelating agents in situ and is thought to be due to a deoxyribonuclease. Preliminary experiments with

  18. Degradation of Poly(L-Lactic acid) and Biocomposites in various Alkaline and Temperature Treatments

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ribbons of poly(lactic acid) (PLA) and PLA containing 10 or 25 % Osage orange (OO) biocomposites of various sized heartwood particles were exposed to soil conditions either outdoors or in a greenhouse. No appreciable degradation was evident even after 200 days treatments. An artificial alkaline de...

  19. Cathepsin B-sensitive polymers for compartment-specific degradation and nucleic acid release

    PubMed Central

    Chu, David S.H.; Johnson, Russell N.; Pun, Suzie H.

    2011-01-01

    Degradable cationic polymers are desirable for in vivo nucleic acid delivery because they offer significantly decreased toxicity over non-degradable counterparts. Peptide linkers provide chemical stability and high specificity for particular endopeptidases but have not been extensively studied for nucleic acid delivery applications. In this work, enzymatically degradable peptide-HPMA copolymers were synthesized by RAFT polymerization of HPMA with methacrylated peptide macromonomers, resulting in polymers with low polydispersity and near quantitative incorporation of peptides. Three peptide-HPMA copolymers were evaluated: (i) pHCathK10, containing peptides composed of the linker phe-lys-phe-leu (FKFL), a substrate of the endosomal/lysosomal endopeptidase cathepsin B, connected to oligo-(l)-lysine for nucleic acid binding, (ii) pHCath(d)K10, containing the FKFL linker with oligo-(d)-lysine, and (iii) pH(d)Cath(d)K10, containing all (d) amino acids. Cathepsin B degraded copolymers pHCathK10 and pHCath(d)K10 within one hour while no degradation of pH(d)Cath(d)K10 was observed. Polyplexes formed with pHCathK10 copolymers show DNA release by 4 hrs of treatment with cathepsin B; comparatively, polyplexes formed with pHCath(d)K10 and pH(d)Cath(d)K10 show no DNA release within 8 hrs. Transfection efficiency in HeLa and NIH/3T3 cells were comparable between the copolymers but pHCathK10 was less toxic. This work demonstrates the successful application of peptide linkers for degradable cationic polymers and DNA release. PMID:22036879

  20. Combining chemical and isotopic measurements to estimate pesticide degradation rates in a fractured-rock aquifer

    NASA Astrophysics Data System (ADS)

    Farlin, Julien; Gallé, Tom; Bayerle, Michael; Pittois, Denis; El-Khabbaz, Hassanya; Schreglmann, Kathrin; Höche, Martina; Elsner, Martin

    2013-04-01

    Encouraged by new regulatory requirements for pesticide registration and authorization, the transport and environmental fate of these compounds in the different environmental compartments has been studied extensively. Degradation rates vary widely depending on hydraulic and chemical characteristics, with the strongest degradation usually occuring in the topsoil. Nonetheless, significant pesticide attenuation may still take place during transport in the aquifer, since residence times are generally much longer than in the soil. Ideally, pesticide transformation in the aquifer needs to be determined under real field conditions. Mass balance calculations however are complicated by the fact that the initial pesticide mass leached from the soil is often not known precisely enough. In this study, isotopic and classical pesticide concentration measurements were combined with groundwater dating techniques to assess the degradation rate of atrazine and its metabolite desethylatrazine in a fractured sandstone. The mass balance problem was solved by introducing the desethylatrazine to atrazine ratio, a relative measure which was used to quantify the advancement of atrazine degradation with increasing transport time in the subsurface. The extent of transformation of the parent compound was finally estimated from the shift in the isotopic signal between soil application and the outlet of the groundwater system.

  1. Radiation-induced 1/f noise degradation of PNP bipolar junction transistors at different dose rates

    NASA Astrophysics Data System (ADS)

    Qi-Feng, Zhao; Yi-Qi, Zhuang; Jun-Lin, Bao; Wei, Hu

    2016-04-01

    It is found that ionizing-radiation can lead to the base current and the 1/f noise degradations in PNP bipolar junction transistors. In this paper, it is suggested that the surface of the space charge region of the emitter-base junction is the main source of the base surface 1/f noise. A model is developed which identifies the parameters and describes their interactive contributions to the recombination current at the surface of the space charge region. Based on the theory of carrier number fluctuation and the model of surface recombination current, a 1/f noise model is developed. This model suggests that 1/f noise degradations are the result of the accumulation of oxide-trapped charges and interface states. Combining models of ELDRS, this model can explain the reason why the 1/f noise degradation is more severe at a low dose rate than at a high dose rate. The radiations were performed in a Co60 source up to a total dose of 700 Gy(Si). The low dose rate was 0.001 Gy(Si)/s and the high dose rate was 0.1 Gy(Si)/s. The model accords well with the experimental results. Project supported by the National Natural Science Foundation of China (Grant Nos. 61076101 and 61204092).

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

    PubMed Central

    Bargiela, Rafael; Gertler, Christoph; Magagnini, Mirko; Mapelli, Francesca; Chen, Jianwei; Daffonchio, Daniele; Golyshin, Peter N.; Ferrer, Manuel

    2015-01-01

    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

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

    PubMed

    Bargiela, Rafael; Gertler, Christoph; Magagnini, Mirko; Mapelli, Francesca; Chen, Jianwei; Daffonchio, Daniele; Golyshin, Peter N; Ferrer, Manuel

    2015-01-01

    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

  4. A method to define degradation mechanisms and failure rates for piping

    SciTech Connect

    Gamble, R.M.; Gosselin, S.R.

    1996-12-01

    This paper describes a process currently being employed to develop an easy to use procedure for identifying degradation mechanisms and computing failure rates for piping. The procedure includes guidelines to identify degradation mechanisms that may be present in piping systems. The identified mechanisms along with other system or segment specific features of the piping determine the piping failure rate. Implementation of this procedure requires a data or knowledge base that reflects the service and operational conditions that affect piping reliability and availability. This procedure is being developed for use by plant engineers, and will not require expertise in probability, stress, or fracture mechanics analyses. The method can be used to provide input for performing plant safety assessments and defining risk based inspection programs.

  5. Arachidonic acid downregulates acyl-CoA synthetase 4 expression by promoting its ubiquitination and proteasomal degradation[S

    PubMed Central

    Kan, Chin Fung Kelvin; Singh, Amar Bahadur; Stafforini, Diana M.; Azhar, Salman; Liu, Jingwen

    2014-01-01

    ACSL4 is a member of the long-chain acyl-CoA synthetase (ACSL) family with a marked preference for arachidonic acid (AA) as its substrate. Although an association between elevated levels of ACSL4 and hepatosteatosis has been reported, the function of ACSL4 in hepatic FA metabolism and the regulation of its functional expression in the liver remain poorly defined. Here we provide evidence that AA selectively downregulates ACSL4 protein expression in hepatic cells. AA treatment decreased the half-life of ACSL4 protein in HepG2 cells by approximately 4-fold (from 17.3 ± 1.8 h to 4.2 ± 0.4 h) without causing apoptosis. The inhibitory action of AA on ACSL4 protein stability could not be prevented by rosiglitazone or inhibitors that interfere with the cellular pathways involved in AA metabolism to biologically active compounds. In contrast, treatment of cells with inhibitors specific for the proteasomal degradation pathway largely prevented the AA-induced ACSL4 degradation. We further show that ACSL4 is intrinsically ubiquitinated and that AA treatment can enhance its ubiquitination. Collectively, our studies have identified a novel substrate-induced posttranslational regulatory mechanism by which AA downregulates ACSL4 protein expression in hepatic cells. PMID:24879802

  6. Characterization of degradation products of ivabradine by LC-HR-MS/MS: a typical case of exhibition of different degradation behaviour in HCl and H2SO4 acid hydrolysis.

    PubMed

    Patel, Prinesh N; Borkar, Roshan M; Kalariya, Pradipbhai D; Gangwal, Rahul P; Sangamwar, Abhay T; Samanthula, Gananadhamu; Ragampeta, Srinivas

    2015-02-01

    A validated stability-indicating HPLC method was established, and comprehensive stress testing of ivabradine, a cardiotonic drug, was carried out as per ICH guidelines. Ivabradine was subjected to acidic, basic and neutral hydrolysis, oxidation, photolysis and thermal stress conditions, and the resulting degradation products were investigated by LC-PDA and LC-HR-MS/MS. The drug was found to degrade in acid and base hydrolysis. An efficient and selective stability assay method was developed on Phenomenex Luna C18 (250 × 4.6 mm, 5.0 µm) column using ammonium formate (10 mM, pH 3.0) and acetonitrile as mobile phase at 30 °C in gradient elution mode. The flow rate was 0.7 ml/min and detection wavelength was 286 nm. A total of five degradation products (I-1 to I-5) were identified and characterized by LC-HR-MS/MS in combination with accurate mass measurements. The drug exhibited different degradation behaviour in HCl and H2SO4 hydrolysis conditions. It is a unique example where two of the five degradation products in HCl hydrolysis were absent in H2SO4 acid hydrolysis. The present study provides guidance to revise the stress test for the determination of inherent stability of drugs containing lactam moiety under hydrolytic conditions. Most probable mechanisms for the formation of degradation products have been proposed on the basis of a comparison of the fragmentation pattern of the drug and its degradation products. In silico toxicity revealed that the degradation products (I-2 to I-5) were found to be severe irritants in case of ocular irritancy. The analytical assay method was validated with respect to specificity, linearity, range, precision, accuracy and robustness. PMID:25800016

  7. Control of the molecular degradation of hyaluronic acid hydrogels for tissue augmentation.

    PubMed

    Oh, Eun Ju; Kang, Sun-Woong; Kim, Byung-Soo; Jiang, Ge; Cho, Il Hwan; Hahn, Sei Kwang

    2008-09-01

    A novel protocol to control the molecular degradation of hyaluronic acid (HA) hydrogels was successfully developed for tissue augmentation applications. HA has a different conformational structure in water and organic solvent, and the carboxyl group of HA is known to be the recognition site of hyaluronidase and HA receptors. Based on these findings, HA was chemically modified by grafting adipic acid dihydrazide (ADH) to the carboxyl group of HA in the water to prepare HA-ADH(WATER) and in the mixed solvent of water and ethanol to prepare degradation-controlled HA-ADH(WATER/ETHANOL). Three kinds of HA hydrogels were prepared by the crosslinking of HA-ADH(WATER) or HA-ADH(WATER/ETHANOL) with bis(sulfosuccinimidyl) suberate, and by the crosslinking of HA-OH with divinyl sulfone (DVS). In vitro and in vivo degradation tests showed that HA-DVS hydrogels were degraded most rapidly, followed by HA-ADH(WATER) hydrogels and HA-ADH(WATER/ETHANOL) hydrogels. There was no adverse effect during and after in vivo degradation tests. All of the HA hydrogel samples appeared to be biocompatible, according to the histological analysis with hematoxylin-eosin and Alcian blue. PMID:18022803

  8. Sequence dependent N-terminal rearrangement and degradation of peptide nucleic acid (PNA) in aqueous solution

    NASA Technical Reports Server (NTRS)

    Eriksson, M.; Christensen, L.; Schmidt, J.; Haaima, G.; Orgel, L.; Nielsen, P. E.

    1998-01-01

    The stability of the PNA (peptide nucleic acid) thymine monomer inverted question markN-[2-(thymin-1-ylacetyl)]-N-(2-aminoaminoethyl)glycine inverted question mark and those of various PNA oligomers (5-8-mers) have been measured at room temperature (20 degrees C) as a function of pH. The thymine monomer undergoes N-acyl transfer rearrangement with a half-life of 34 days at pH 11 as analyzed by 1H NMR; and two reactions, the N-acyl transfer and a sequential degradation, are found by HPLC analysis to occur at measurable rates for the oligomers at pH 9 or above. Dependent on the amino-terminal sequence, half-lives of 350 h to 163 days were found at pH 9. At pH 12 the half-lives ranged from 1.5 h to 21 days. The results are discussed in terms of PNA as a gene therapeutic drug as well as a possible prebiotic genetic material.

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

    PubMed

    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

  10. Sulfate radical-induced degradation of Acid Orange 7 by a new magnetic composite catalyzed peroxymonosulfate oxidation process.

    PubMed

    Chen, Dan; Ma, Xiaolong; Zhou, Jizhi; Chen, Xi; Qian, Guangren

    2014-08-30

    We synthesized a novel magnetic composite, Fe3O4/Cu(Ni)Cr-LDH, as a heterogeneous catalyst for the degradation of organic dyes in the solution using sulfate radical-based advanced oxidation processes. The physicochemical properties of the composite synthesized via two-step microwave hydrothermal method were characterized by several techniques, such as X-ray diffraction (XRD), inductively coupled plasma (ICP), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The degradation tests were performed at 25°C with Acid Orange 7 (AO7) initial concentration of 25mg/L and AO7/peroxymonosulfate (PMS) molar ratio of 1:10, which showed that the complete degradation by Fe3O4/Cu1.5Ni0.5Cr-LDH could be achieved and the mineralization rate could reach 46%. PMS was activated by Cu (II) and Fe (II/III) of Fe3O4/Cu(Ni)Cr-LDH to generate sulfate radicals (SO4(-)). Subsequently, the organic functional groups of AO7 molecules were destroyed by sulfate radicals (SO4(-)), inducing the degradation of AO7. Moreover, the catalytic behavior of the catalysts could be reused five times. Therefore, our work suggested that the Fe3O4/Cu(Ni)Cr-LDH composite could be applied widely for the treatment of organic dyes in wastewater. PMID:25103453

  11. Bacterial secondary production on vascular plant detritus: relationships to detritus composition and degradation rate.

    PubMed Central

    Moran, M A; Hodson, R E

    1989-01-01

    Bacterial production at the expense of vascular plant detritus was measured for three emergent plant species (Juncus effusus, Panicum hemitomon, and Typha latifolia) degrading in the littoral zone of a thermally impacted lake. Bacterial secondary production, measured as tritiated thymidine incorporation into DNA, ranged from 0.01 to 0.81 microgram of bacterial C mg of detritus-1 day-1. The three plant species differed with respect to the amount of bacterial productivity they supported per milligram of detritus, in accordance with the predicted biodegradability of the plant material based on initial nitrogen content, lignin content, and C/N ratio. Bacterial production also varied throughout the 22 weeks of in situ decomposition and was positively related to the nitrogen content and lignin content of the remaining detritus, as well as to the temperature of the lake water. Over time, production was negatively related to the C/N ratio and cellulose content of the degrading plant material. Bacterial production on degrading plant material was also calculated on the basis of plant surface area and ranged from 0.17 to 1.98 micrograms of bacterial C cm-2 day-1. Surface area-based calculations did not correlate well with either initial plant composition or changing composition of the remaining detritus during decomposition. The rate of bacterial detritus degradation, calculated from measured production of surface-attached bacteria, was much lower than the actual rate of weight loss of plant material. This discrepancy may be attributable to the importance of nonbacterial organisms in the degradation and loss of plant material from litterbags or to the microbially mediated solubilization of particulate material prior to bacterial utilization, or both. PMID:2802603

  12. In situ determination of the rate of unassisted degradation of saturated-zone hydrocarbon contamination

    SciTech Connect

    Kerfoot, H.B.

    1994-07-01

    A method to measure the in situ degradation rate of dissolved hydrocarbon contamination has been developed and applied at two locations at a field site. The method uses the rates of downward diffusion of oxygen and upward diffusion of carbon dioxide through the unsaturated zone, as calculated from vertical soil-gas concentration gradients, combined with stoichiometry to obtain two degradation rates in hydrocarbon mass per water table surface area per time. Values of 0.385 gram per m{sup 2} per day and 0.52 gram per m{sup 2} per day (based upon oxygen data) and 0.056 gram per m{sup 2} per day and 0.12 gram per m{sup 2} per day (based upon carbon dioxide data) were calculated at a field site with dissolved fuel contamination. This result of lower values from ground-air carbon dioxide concentrations is consistent with a significant fraction of the carbon dioxide produced being lost to the aqueous phase. Based upon a single-stage equilibrium phase-transfer model, gas/water volume ratios of 0.02 and 0.2 for the capillary fringe were calculated. Groundwater carbon dioxide fugacities and soil-gas carbon dioxide concentrations were used at the two locations and a third to determine whether the source of elevated soil carbon dioxide concentrations were unsaturated-zone hydrocarbon degradation or a saturated-zone process. 11 refs., 2 figs., 2 tabs.

  13. Relationship of Bacterial Richness to Organic Degradation Rate and Sediment Age in Subseafloor Sediment

    PubMed Central

    Walsh, Emily A.; Kirkpatrick, John B.; Pockalny, Robert; Sauvage, Justine; Spivack, Arthur J.; Murray, Richard W.; Sogin, Mitchell L.

    2016-01-01

    ABSTRACT Subseafloor sediment hosts a large, taxonomically rich, and metabolically diverse microbial ecosystem. However, the factors that control microbial diversity in subseafloor sediment have rarely been explored. Here, we show that bacterial richness varies with organic degradation rate and sediment age. At three open-ocean sites (in the Bering Sea and equatorial Pacific) and one continental margin site (Indian Ocean), richness decreases exponentially with increasing sediment depth. The rate of decrease in richness with increasing depth varies from site to site. The vertical succession of predominant terminal electron acceptors correlates with abundance-weighted community composition but does not drive the vertical decrease in richness. Vertical patterns of richness at the open-ocean sites closely match organic degradation rates; both properties are highest near the seafloor and decline together as sediment depth increases. This relationship suggests that (i) total catabolic activity and/or electron donor diversity exerts a primary influence on bacterial richness in marine sediment and (ii) many bacterial taxa that are poorly adapted for subseafloor sedimentary conditions are degraded in the geologically young sediment, where respiration rates are high. Richness consistently takes a few hundred thousand years to decline from near-seafloor values to much lower values in deep anoxic subseafloor sediment, regardless of sedimentation rate, predominant terminal electron acceptor, or oceanographic context. IMPORTANCE Subseafloor sediment provides a wonderful opportunity to investigate the drivers of microbial diversity in communities that may have been isolated for millions of years. Our paper shows the impact of in situ conditions on bacterial community structure in subseafloor sediment. Specifically, it shows that bacterial richness in subseafloor sediment declines exponentially with sediment age, and in parallel with organic-fueled oxidation rate. This result

  14. Adsorption and degradation of the weak acid mesotrione in soil and environmental fate implications.

    PubMed

    Dyson, J S; Beulke, S; Brown, C D; Lane, M C G

    2002-01-01

    The ability of soils to adsorb and degrade pesticides strongly influences their environmental fate. This paper examines the adsorption and degradation of a weak acid, a new herbicide mesotrione 12-[4-(methylsulfonyl)-2-nitrobenzoyl]-1,3-cyclohexanedione], in 15 different soils from Europe and the USA. Experiments were conducted to understand the influence of soil properties, covering a wide range of soil textures, soil pH values (4.4 to 7.5), and organic carbon contents (0.6 to 3.35%). Mesotrione adsorption (Kd values ranged from 0.13 to 5.0 L/kg) was primarily related to soil pH, and to a lesser extent by percent organic carbon (%OC). As soil pH rose. mesotrione Kd values got smaller as mesotrione dissociated from the molecular to anionic form. Mesotrione degradation (half-lives ranged from 4.5 to 32 d) was also related to soil pH, getting shorter as soil pH rose. Simple regression of mesotrione adsorption against soil pH and %OC and against degradation provided a close fit to the data. The correlation between mesotrione adsorption and degradation means that Kd and half-life values are only relevant for use in environmental fate assessment if these values are "paired" for the same soil pH and %OC. The implications were as illustrated for leaching, raising important issues about combining pesticide adsorption and degradation behavior in environmental fate assessments. PMID:11931453

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

    PubMed

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

    PubMed Central

    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

  17. PAHs in soils: Sorption versus degradation - elucidation of rate-limiting processes

    NASA Astrophysics Data System (ADS)

    Herklotz, Ilka; Gocht, Tilman; Grathwohl, Peter

    2010-05-01

    soil are capable to degrade PAHs. Nevertheless strong sorption and high organic carbon content in this soil prevent these microorganisms from degrading the native PAHs. The results were implemented into a mass balance model considering both, sorption and degradation. The calculations were conducted with first order rate constant λ taken from the non-soil-containing experiment, and revealed a half-life of phenanthrene up to almost one century. Keywords: PAH, degradation, sorption

  18. Degradation behavior of hydroxyapatite/poly(lactic-co-glycolic) acid nanocomposite in simulated body fluid

    SciTech Connect

    Liuyun, Jiang; Chengdong, Xiong; Lixin, Jiang; Lijuan, Xu

    2013-10-15

    Graphical abstract: In this manuscript, we initiated a systematic study to investigate the effect of HA on thermal properties, inner structure, reduction of mechanical strength, surface morphology and the surface deposit of n-HA/PLGA composite with respect to the soaking time. The results showed that n-HA played an important role in improving the degradation behavior of n-HA/PLGA composite, which can accelerate the degradation of n-HA/PLGA composite and endow it with bioactivity, after n-HA was detached from PLGA during the degradation, so that n-HA/PLGA composite may have a more promising prospect of the clinical application than pure PLGA as bone fracture internal fixation materials, and the results would be of reference significance to predict the in vivo degradation and biological properties. - Highlights: • Effect of n-HA on degradation behavior of n-HA/PLGA composite was investigated. • Degradation behaviors of n-HA/PLGA and PLGA were carried out in SBF for 6 months. • Viscosity, thermal properties, inner structure and bending strength were tested. • n-HA can accelerate the degradation and endows it with bioactivity. - Abstract: To investigate the effect of hydroxyapatite(HA) on the degradation behavior of hydroxyapatite/poly(lactic-co-glycolic) acid (HA/PLGA) nanocomposite, the degradation experiment of n-HA/PLGA composite and pure PLGA were carried out by soaking in simulated body fluid(SBF) at 37 °C for 1, 2, 4 and 6 months. The change of intrinsic viscosity, thermal properties, inner structure, bending strength reduction, surface morphology and the surface deposit of n-HA/PLGA composite and pure PLGA with respect to the soaking time were investigated by means of UbbeloHde Viscometer, differential scanning calorimeter (DSC), scanning electron microscope(SEM), electromechanical universal tester, a conventional camera and X-ray diffraction (XRD). The results showed that n-HA played an important role in improving the degradation behavior of n

  19. Screening and characterization of purine nucleoside degrading lactic acid bacteria isolated from Chinese sauerkraut and evaluation of the serum uric acid lowering effect in hyperuricemic rats.

    PubMed

    Li, Ming; Yang, Dianbin; Mei, Lu; Yuan, Lin; Xie, Ao; Yuan, Jieli

    2014-01-01

    Hyperuricemia is well known as the cause of gout. In recent years, it has also been recognized as a risk factor for arteriosclerosis, cerebrovascular and cardiovascular diseases, and nephropathy in diabetic patients. Foods high in purine compounds are more potent in exacerbating hyperuricemia. Therefore, the development of probiotics that efficiently degrade purine compounds is a promising potential therapy for the prevention of hyperuricemia. In this study, fifty-five lactic acid bacteria isolated from Chinese sauerkraut were evaluated for the ability to degrade inosine and guanosine, the two key intermediates in purine metabolism. After a preliminary screening based on HPLC, three candidate strains with the highest nucleoside degrading rates were selected for further characterization. The tested biological characteristics of candidate strains included acid tolerance, bile tolerance, anti-pathogenic bacteria activity, cell adhesion ability, resistance to antibiotics and the ability to produce hydrogen peroxide. Among the selected strains, DM9218 showed the best probiotic potential compared with other strains despite its poor bile resistance. Analysis of 16S rRNA sequences showed that DM9218 has the highest similarity (99%) to Lactobacillus plantarum WCFS1. The acclimated strain DM9218-A showed better resistance to 0.3% bile salt, and its survival in gastrointestinal tract of rats was proven by PCR-DGGE. Furthermore, the effects of DM9218-A in a hyperuricemia rat model were evaluated. The level of serum uric acid in hyperuricemic rat can be efficiently reduced by the intragastric administration of DM9218-A (P<0.05). The preventive treatment of DM9218-A caused a greater reduction in serum uric acid concentration in hyperuricemic rats than the later treatment (P<0.05). Our results suggest that DM9218-A may be a promising candidate as an adjunctive treatment in patients with hyperuricemia during the onset period of disease. DM9218-A also has potential as a probiotic

  20. Reaction mechanisms and rate constants of waste degradation in landfill bioreactor systems with enzymatic-enhancement.

    PubMed

    Jayasinghe, P A; Hettiaratchi, J P A; Mehrotra, A K; Kumar, S

    2014-06-01

    Augmenting leachate before recirculation with peroxidase enzymes is a novel method to increase the available carbon, and therefore the food supply to microorganisms at the declining phase of the anaerobic landfill bioreactor operation. In order to optimize the enzyme-catalyzed leachate recirculation process, it is necessary to identify the reaction mechanisms and determine rate constants. This paper presents a kinetic model developed to ascertain the reaction mechanisms and determine the rate constants for enzyme catalyzed anaerobic waste degradation. The maximum rate of reaction (Vmax) for MnP enzyme-catalyzed reactors was 0.076 g(TOC)/g(DS).day. The catalytic turnover number (k(cat)) of the MnP enzyme-catalyzed was 506.7 per day while the rate constant (k) of the un-catalyzed reaction was 0.012 per day. PMID:24759644

  1. Collagen synthesis and degradation in vivo. Evidence for rapid rates of collagen turnover with extensive degradation of newly synthesized collagen in tissues of the adult rat.

    PubMed

    McAnulty, R J; Laurent, G J

    1987-06-01

    Collagen turnover is now known to occur more rapidly in body tissues than traditionally believed, but the kinetics and mechanisms for degradation are still poorly understood. Here we measure collagen synthesis rates and the proportion of newly synthesized collagen (probably procollagen) which is rapidly degraded, in tissues of the adult rat after injection of [14C]-proline with a large "flooding" dose of unlabelled proline. Incorporation of [14C]-proline into lung, heart, skeletal muscle and skin collagen and its appearance as hydroxy [14C]-proline, free or in small molecular weight moieties, at various times up to one hour, suggested extremely rapid synthesis and degradation for some tissues of the adult rat. Values in heart, lung, skeletal muscle and skin (with the proportion of degradation of newly synthesized collagen shown in parentheses) were 5.2 +/- 0.7%/day (53 +/- 5%), 9.0 +/- 0.7%/day (37 +/- 2%), 2.2 +/- 0.3%/day (38 +/- 7%) and 4.4 +/- 1.3%/day (8.8 +/- 0.5%). These data provide in vivo evidence, which are consistent with the observation in isolated cells, that a proportion of newly synthesized collagen is degraded rapidly, and probably intracellularly, after its synthesis. They also indicate that collagen may be synthesized and degraded rapidly in normal rat tissues, but the mean turnover rates and the proportions of collagen degraded intracellularly vary widely between tissues. PMID:3497767

  2. Identification of insulin domains important for binding to and degradation by endosomal acidic insulinase.

    PubMed

    Authier, F; Danielsen, G M; Kouach, M; Briand, G; Chauvet, G

    2001-01-01

    The endosomal compartment of hepatic parenchymal cells contains an acidic endopeptidase, endosomal acidic insulinase (EAI), which hydrolyzes internalized insulin at a limited number of sites. Although the positions of these cleavages are partially known, the residues of insulin important in its binding to and proteolysis by EAI have not been defined. To this end, we have studied the degradation over time of native human insulin and three insulin-analog peptides using a soluble endosomal extract from rat liver parenchyma followed by purification of the products by HPLC and determination of their structure by mass spectrometry. We found variable rates of ligand processing, i.e. high ([Asp(B10)]- and [Glu(A13),Glu(B10)]-insulin), moderate (insulin) and low (the H2-analog). On the basis of IC(50) values, competition studies revealed that human and mutant insulins display nearly equivalent affinity for the EAI. Proteolysis of human and mutant insulins by EAI resulted in eight cleavages in the B-chain which occurred in the central region (Glu(B13)-Leu(B17)) and at the C-terminus (Arg(B22)-Thr(B27)), the latter region comprising the initial cleavages at Phe(B24)-Phe(B25) (major pathway) and Phe(B25)-Tyr(B26) (minor pathway) bonds. Except for the [Glu(A13),Glu(B10)]-insulin mutant, only one cleavage on the A-chain was observed at residues Gln(A15)-Leu(A16). Analysis of the nine cleavage sites showed a preference for hydrophobic and aromatic amino acid residues on both the carboxyl and amino sides of a cleaved peptide bond. Using the B-chain alone as a substrate resulted in a 30-fold increase in affinity for EAI and a 6-fold increase in the rate of hydrolysis compared with native insulin. A similar role for the C-terminal region of the B-chain of insulin in the high-affinity recognition of EAI was supported by the use of the corresponding B(22)-B(30) peptide, which displayed an increase in EAI affinity similar to the entire B-chain vs. wild-type insulin. Thus, we have

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

    PubMed Central

    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

  4. Enhanced Photocatalytic Degradation of Salicylic Acid in Water-ethanol Mixtures from Titanium Dioxide Grafted with Hexadecyltrichlorosilane

    NASA Astrophysics Data System (ADS)

    Kassir, Mounir; Roques-Carmes, Thibault; Assaker, Karine; Hamieh, Tayssir; Razafitianamaharavo, Angelina; Toufaily, Joumana; Villiéras, Frédéric

    The aim of this paper is to study the effect of the chemical modification on the photocatalytic properties of TiO2. The TiO2 Degussa-P25 nanoparticles are chemically modified using the hydrophobic organosilane hexadecyltrichlorosilane (HTS). The samples are employed as catalysts for salicylic acid photocatalytic oxidation in water-ethanol mixtures. The kinetics of salicylic acid photodegradation is investigated as a function of ethanol content in water-ethanol mixtures and initial HTS concentrations. The results indicate that the HTS groups are not degraded during the photocatalytic process. The TiO2 grafted by HTS is more efficient than bare TiO2 for the photodegradation process in presence of ethanol. The photodegradation process follows first order kinetics and the apparent rate constant increases linearly with the initial HTS concentration (amount of HTS grafted).

  5. Degradation and annealing studies on gamma rays irradiated COTS PPD CISs at different dose rates

    NASA Astrophysics Data System (ADS)

    Wang, Zujun; Ma, Yingwu; Liu, Jing; Xue, Yuan; He, Baoping; Yao, Zhibin; Huang, Shaoyan; Liu, Minbo; Sheng, Jiangkun

    2016-06-01

    The degradation and annealing studies on Colbalt-60 gamma-rays irradiated commercial-off-the-shelf (COTS) pinned photodiode (PPD) CMOS image sensors (CISs) at the various dose rates are presented. The irradiation experiments of COTS PPD CISs are carried out at 0.3, 3.0 and 30.0 rad(Si)/s. The COTS PPD CISs are manufactured using a standard 0.18-μm CMOS technology with four-transistor pixel PPD architecture. The behavior of the tested CISs shows a remarkable degradation after irradiation and differs in the dose rates. The dark current, dark signal non-uniformity (DSNU), random noise, saturation output, signal to noise ratio (SNR), and dynamic range (DR) versus the total ionizing dose (TID) at the various dose rates are investigated. The tendency of dark current, DSNU, and random noise increase and saturation output, SNR, and DR to decrease at 3.0 rad(Si)/s are far greater than those at 0.3 and 30.0 rad(Si)/s. The damage mechanisms caused by TID irradiation at the various dose rates are also analyzed. The annealing tests are carried out at room temperature with unbiased conditions after irradiation.

  6. Culturing oil sands microbes as mixed species communities enhances ex situ model naphthenic acid degradation

    PubMed Central

    Demeter, Marc A.; Lemire, Joseph A.; Yue, Gordon; Ceri, Howard; Turner, Raymond J.

    2015-01-01

    Oil sands surface mining for bitumen results in the formation of oil sands process water (OSPW), containing acutely toxic naphthenic acids (NAs). Potential exists for OSPW toxicity to be mitigated by aerobic degradation of the NAs by microorganisms indigenous to the oil sands tailings ponds, the success of which is dependent on the methods used to exploit the metabolisms of the environmental microbial community. Having hypothesized that the xenobiotic tolerant biofilm mode-of-life may represent a feasible way to harness environmental microbes for ex situ treatment of OSPW NAs, we aerobically grew OSPW microbes as single and mixed species biofilm and planktonic cultures under various conditions for the purpose of assaying their ability to tolerate and degrade NAs. The NAs evaluated were a diverse mixture of eight commercially available model compounds. Confocal microscopy confirmed the ability of mixed and single species OSPW cultures to grow as biofilms in the presence of the NAs evaluated. qPCR enumeration demonstrated that the addition of supplemental nutrients at concentrations of 1 g L-1 resulted in a more numerous population than 0.001 g L-1 supplementation by approximately 1 order of magnitude. GC-FID analysis revealed that mixed species cultures (regardless of the mode of growth) are the most effective at degrading the NAs tested. All constituent NAs evaluated were degraded below detectable limits with the exception of 1-adamantane carboxylic acid (ACA); subsequent experimentation with ACA as the sole NA also failed to exhibit degradation of this compound. Single species cultures degraded select few NA compounds. The degradation trends highlighted many structure-persistence relationships among the eight NAs tested, demonstrating the effect of side chain configuration and alkyl branching on compound recalcitrance. Of all the isolates, the Rhodococcus spp. degraded the greatest number of NA compounds, although still less than the mixed species cultures

  7. Balancing sample accumulation and DNA degradation rates to optimize noninvasive genetic sampling of sympatric carnivores.

    PubMed

    Lonsinger, Robert C; Gese, Eric M; Dempsey, Steven J; Kluever, Bryan M; Johnson, Timothy R; Waits, Lisette P

    2015-07-01

    Noninvasive genetic sampling, or noninvasive DNA sampling (NDS), can be an effective monitoring approach for elusive, wide-ranging species at low densities. However, few studies have attempted to maximize sampling efficiency. We present a model for combining sample accumulation and DNA degradation to identify the most efficient (i.e. minimal cost per successful sample) NDS temporal design for capture-recapture analyses. We use scat accumulation and faecal DNA degradation rates for two sympatric carnivores, kit fox (Vulpes macrotis) and coyote (Canis latrans) across two seasons (summer and winter) in Utah, USA, to demonstrate implementation of this approach. We estimated scat accumulation rates by clearing and surveying transects for scats. We evaluated mitochondrial (mtDNA) and nuclear (nDNA) DNA amplification success for faecal DNA samples under natural field conditions for 20 fresh scats/species/season from <1-112 days. Mean accumulation rates were nearly three times greater for coyotes (0.076 scats/km/day) than foxes (0.029 scats/km/day) across seasons. Across species and seasons, mtDNA amplification success was ≥95% through day 21. Fox nDNA amplification success was ≥70% through day 21 across seasons. Coyote nDNA success was ≥70% through day 21 in winter, but declined to <50% by day 7 in summer. We identified a common temporal sampling frame of approximately 14 days that allowed species to be monitored simultaneously, further reducing time, survey effort and costs. Our results suggest that when conducting repeated surveys for capture-recapture analyses, overall cost-efficiency for NDS may be improved with a temporal design that balances field and laboratory costs along with deposition and degradation rates. PMID:25454561

  8. Rumen Degradability and Post-ruminal Digestion of Dry Matter, Nitrogen and Amino Acids of Three Protein Supplements

    PubMed Central

    Gao, Wei; Chen, Aodong; Zhang, Bowen; Kong, Ping; Liu, Chenli; Zhao, Jie

    2015-01-01

    This study evaluated the in situ ruminal degradability, and subsequent small intestinal digestibility (SID) of dry matter, crude protein (CP), and amino acids (AA) of cottonseed meal (CSM), sunflower seed meal (SFSM) and distillers dried grains with solubles (DDGS) by using the modified three-step in vitro procedure. The ruminal degradability and subsequent SID of AA in rumen-undegradable protein (RUP-AA) varied among three protein supplements. The result show that the effective degradability of DM for SFSM, CSM, and DDGS was 60.8%, 56.4%, and 41.0% and their ruminal fermentable organic matter was 60.0%, 55.9%, and 39.9%, respectively. The ruminal degradable protein (RDP) content in CP for SFSM, CSM, and DDGS was 68.3%, 39.0%, and 32.9%, respectively, at the ruminal solid passage rate of 1.84%/h. The SFSM is a good source of RDP for rumen micro-organisms; however, the SID of RUP of SFSM was lower. The DDGS and CSM are good sources of RUP for lambs to digest in the small intestine to complement ruminal microbial AA of growing lambs. Individual RUP-AA from each protein source was selectively removed by the rumen micro-organisms, especially for Trp, Arg, His, and Lys (p<0.01). The SID of individual RUP-AA was different within specific RUP origin (p<0.01). Limiting amino acid was Leu for RUP of CSM and Lys for both RUP of SFSM and DDGS, respectively. Therefore, different protein supplements with specific limitations should be selected and combined carefully in growing lambs ration to optimize AA balance. PMID:25656208

  9. Requirement for alanine in the amino acid control of deprivation-induced protein degradation in liver.

    PubMed Central

    Pösö, A R; Mortimore, G E

    1984-01-01

    Protein degradation in liver is actively controlled by a small group of inhibitory amino acids--leucine, tyrosine (or phenylalanine), glutamine, proline, histidine, tryptophan, and methionine. Other evidence, however, suggests that one or more of the remaining 12 noninhibitory amino acids is also required for suppression of proteolysis at normal concentrations. This question was investigated in livers of fed rats perfused in the single-pass mode. The deletion of alanine at normal (1x), but not at 4x or 10x normal, plasma amino acid concentrations evoked a near-maximal acceleration of protein degradation. No other noninhibitory amino acid was effective. Because alanine alone was not directly inhibitory and its omission was not associated with a decrease in inhibitory amino acid pools, alanine was presumed to act as a coregulator in the expression of inhibitory activity. When tested alone, the inhibitory group was as effective as the complete mixture at 0.5x and 4x levels, but it lost its suppressive ability within a narrow zone of concentration centered slightly above 1x. The addition of 1x (0.48 mM) alanine completely restored the inhibition. Pyruvate and lactate could be effectively substituted, but only at concentrations 10-20 times greater than that of alanine. These, together with earlier findings, indicate the existence of a regulatory complex that recognizes specific amino acids and transmits positive and negative signals to proteolytic sites. The results also suggest that alanine can provide an important regulatory link between energy demands and protein degradation. PMID:6589593

  10. The Degradation of 14C-Glutamic Acid by L-Glutamic Acid Decarboxylase.

    ERIC Educational Resources Information Center

    Dougherty, Charles M; Dayan, Jean

    1982-01-01

    Describes procedures and semi-micro reaction apparatus (carbon dioxide trap) to demonstrate how a particular enzyme (L-Glutamic acid decarboxylase) may be used to determine the site or sites of labeling in its substrate (carbon-14 labeled glutamic acid). Includes calculations, solutions, and reagents used. (Author/SK)

  11. Degradation of 2,4-dichlorophenoxyacetic acid by a halotolerant strain of Penicillium chrysogenum: antibiotic production.

    PubMed

    Ferreira-Guedes, Sumaya; Mendes, Benilde; Leitão, Ana Lúcia

    2012-01-01

    The extensive use of pesticides in agriculture has prompted intensive research on chemical and biological methods in order to protect contamination of water and soil resources. In this paper the degradation of the pesticide 2,4-dichlorophenoxyacetic acid by a Penicillium chrysogenum strain previously isolated from a salt mine was studied in batch cultures. Co-degradation of 2,4-dichlorophenoxyacetic acid with additives such as sugar and intermediates of pesticide metabolism was also investigated. Penicillium chrysogenum in solid medium was able to grow at concentrations up to 1000 mg/L of 2,4-dichlorophenoxyacetic acid (2,4-D) with sucrose. Meanwhile, supplementation of the solid medium with glucose and lactose led to fungal growth at concentrations up to 500 mg/L of herbicide. Batch cultures of 2,4-D at 100 mg/L were developed under aerobic conditions with the addition of glucose, lactose and sucrose, showing sucrose as the best additional carbon source. The 2,4-D removal was quantified by liquid chromatography. The fungus was able to use 2,4-D as the sole carbon and energy source under 0%, 2% and 5.9% NaCl. The greatest 2,4-D degradation efficiency was found using alpha-ketoglutarate and ascorbic acid as co-substrates under 2% NaCl at pH 7. Penicillin production was evaluated in submerged cultures by bioassay, and higher amounts of beta-lactam antibiotic were produced when the herbicide was alone. Taking into account the ability of P. chrysogenum CLONA2 to degrade aromatic compounds, this strain could be an interesting tool for 2,4-D herbicide remediation in saline environments. PMID:22629643

  12. An okadaic acid-sensitive phosphatase negatively controls the cyclin degradation pathway in amphibian eggs.

    PubMed Central

    Lorca, T; Fesquet, D; Zindy, F; Le Bouffant, F; Cerruti, M; Brechot, C; Devauchelle, G; Dorée, M

    1991-01-01

    Inhibition of okadaic acid-sensitive phosphatases released the cyclin degradation pathway from its inhibited state in extracts prepared from unfertilized Xenopus eggs arrested at the second meiotic metaphase. It also switched on cyclin protease activity in a permanent fashion in interphase extracts prepared from activated eggs. Even after cdc2 kinase inactivation, microinjection of okadaic acid-treated interphase extracts pushed G2-arrested recipient oocytes into the M phase, suggesting that the phosphatase inhibitor stabilizes the activity of an unidentified factor which shares in common with cdc2 kinase the maturation-promoting factor activity. Images PMID:1846666

  13. BIOGEOCHEMICAL CYCLING OF ORGANIC MATTER IN ACIDIC ENVIRONMENTS: ARE MICROBIAL DEGRADATIVE PROCESSES ADAPTED TO LOW PH

    EPA Science Inventory

    The rates of microbial degradation of a variety of dissolved and particulate substrates in water and sediment from the Okenofee Swamp, Georgia, and Corkscrew Swamp, Florida, are compared. These two wetland ecosystems share many of the same types of plant communities and both are ...

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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. Degradation of bromamine acid by nanoscale zero-valent iron (nZVI) supported on sepiolite.

    PubMed

    Fei, Xuening; Cao, Lingyun; Zhou, Lifeng; Gu, Yingchun; Wang, Xiaoyang

    2012-01-01

    Sepiolite, a natural nano-material, was chosen as a carrier to prepare supported nanoscale zero-valent iron (nZVI). The effects of preparation conditions, including mass ratio of nZVI and activated sepiolite and preparation pH value, on properties of the supported nZVI were investigated. The results showed that the optimal mass ratio of nZVI and sepiolite was 1.12:1 and the optimal pH value was 7. The supported nZVI was characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and energy dispersive spectrometer (EDS), and furthermore an analogy model of the supported nZVI was set up. Compared with the nZVI itself, the supported nZVI was more stable in air and possessed better water dispersibility, which were beneficial for the degradation of bromamine acid aqueous solution. The degradation characteristics, such as effects of supported nZVI dosage, initial concentration and initial pH value of the solution on the decolorization efficiency were also investigated. The results showed that in an acidic environment the supported nZVI with a dosage of 2 g/L showed high activity in the degradation of bromamine acid with an initial concentration of 1,000 mg/L, and the degree of decolorization could reach up to 98%. PMID:23109568

  17. Optimized photocatalytic degradation of caffeic acid by sol-gel TiO₂.

    PubMed

    García-Montelongo, Xiomara L; Martínez-de la Cruz, Azael; Contreras, David; Mansilla, Héctor D

    2015-01-01

    TiO₂anatase powder was prepared by means of the sol-gel method with titanium(IV) butoxide as precursor. The formation of a tetragonal crystal structure of TiO₂anatase at 500 °C was confirmed by X-ray powder diffraction. The characterization of the samples synthesized was complemented by scanning electron microscopy, diffuse reflectance infrared Fourier transform spectroscopy, nitrogen adsorption-desorption isotherms (Brunauer-Emmett-Teller) and diffuse reflectance spectroscopy. The photocatalytic activity of the TiO₂anatase powder was evaluated in the degradation of caffeic acid in aqueous solution under ultraviolet radiation. A central composite circumscribed design was used to assess the weight of the experimental variables, pH and amount of catalyst in the percentage of caffeic acid degraded and the optimal conditions. The optimized conditions were found to be pH = 5.2 and a load of TiO₂of 1.1 g L⁻¹. Under these conditions more than 90% of caffeic acid degradation was achieved after 30 min of lamp irradiation. At this time the mineralization reached was almost 60%. PMID:25812097

  18. Trifluoroacetic Acid from Degradation of HCFCs and HFCs: A Three-Dimensional Modeling Study

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

    Trifluoroacetic acid (TFA; CF3COOH) 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 CI), 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 environments, pointing to the need to obtain information on the concentrations of TFA in rainwater over scales ranging from local to continental. Based on projected concentrations for HFC-134a, HCFC-124, and HCFC-123 of 80, 10, and 1 pptv in the year 2010, mass conservation arguments imply an annually averaged global concentration of 0.16 micro g/L if washout were the only removal mechanism for TFA. We present 3-D simulations of the HFC/HCFC precursors of TFA that include the rates of formation and deposition of TFA based on assumed future emissions. An established (GISS/Harvard/ UCI) but coarse-resolution (8 deg latitude by 10 deg longitude) chemical transport model was used. The annually averaged rainwater concentration of 0.12 micro g/L (global) was calculated for the year 2010, when both washout and dry deposition are included as the loss mechanism for TFA from the atmosphere. For some large regions in midnorthern latitudes, values are larger, 0.15-0.20 micro g/L. The highest monthly averaged rainwater concentrations of TFA for northern midlatitudes were calculated for the month of July, corresponding to 0.3-0.45 micro g/L in parts of North America and Europe. Recent laboratory experiments have suggested that a substantial amount of vibrationally excited CF3CHFO is produced in the degradation of HFC-134a, decreasing the yield of TFA from this compound by 60%. This decrease would reduce the calculated amounts of TFA in rainwater in the year 2010 by 26%, for the same projected

  19. Trifluoroacetic Acid from Degradation of HCFCs and HFCs: A Three-dimensional Modeling Study

    NASA Technical Reports Server (NTRS)

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

    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 CI), 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 environments, pointing to the need to obtain information on the concentrations of TFA in rainwater over scales ranging from local to continental. Based on projected concentrations for HFC-134a, HCFC-124, and HCFC-123 of 80, 10, and 1 pptv in the year 2010, mass conservation arguments imply an annually averaged global concentration of 0.16 microg/L if washout were the only removal mechanism for TFA. We present 3-D simulations of the HFC/HCFC precursors of TFA that include the rates of formation and deposition of TFA based on assumed future emissions. An established (GISS/Harvard/ UCI) but coarse-resolution (8 deg latitude by 10 deg longitude) chemical transport model was used. The anually averaged rainwater concentration of 0.12 gg/L (global) was calculated for the year 2010, when both washout and dry deposition are included as the loss mechanism for TFA from the atmosphere. For some large regions in midnorthern latitudes, values are larger, 0.15-0.20 microg/L. The highest monthly averaged rainwater concentrations of TFA for northern midlatitudes were calculated for the month of July, corresponding to 0.3-0.45 microg/L in parts of North America and Europe. Recent laboratory experiments have suggested that a substantial amount of vibrationally excited CF3CHFO is produced in the degradation of HFC-134a, decreasing the yield of TFA from this compound by 60%. This decrease would reduce the calculated amounts of TFA in rainwater in the year 2010 by 26%, for the same projected

  20. Trifluoroacetic Acid from Degradation of HCFCs and HFCs: A Three-Dimensional Modeling Study. Appendix P

    NASA Technical Reports Server (NTRS)

    Kotamarthi, V. R.; Rodriquez, J. M.; 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 CI), followed by in-cloud hydrolysis of CF 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 environments, pointing to the need to obtain information on the concentrations of TFA in rainwater over scales ranging from local to continental. Based on projected concentrations for HFC-134a, HCFC-124, and HCFC-123 of 80, 10, and 1 pptv in the year 2010, mass conservation arguments imply an annually averaged global concentration of 0.16 micro g/L if washout were the only removal mechanism for TFA. We present 3-D simulations of the HFC/HCFC precursors of TFA that include the rates of formation and deposition of TFA based on assumed future emissions. An established (GISS[Harvard/ UCI) but coarse-resolution (8 deg latitude by 10 deg longitude) chemical transport model was used. The annually averaged rainwater concentration of 0.12 micro g/L (global) was calculated for the year 2010, when both washout and dry deposition are included as the loss mechanism for TFA from the atmosphere. For some large regions in midnorthern latitudes, values are larger. 0.15-0.20 micro g/L. The highest monthly averaged rainwater concentrations of TFA for northern midlatitudes were calculated for the month of July, corresponding to 0.3 - 0.45 micro g/L in parts of North America and Europe. Recent laboratory experiments have suggested that a substantial amount of vibrationally excited CF3CHFO is produced in the degradation of HFC-134a, decreasing the yield of TFA from this compound by 60%. This decrease would reduce the calculated amounts of TFA in rainwater in the year 2010 by 26%, for the same projected

  1. Aspartic Acid Racemization and Collagen Degradation Markers Reveal an Accumulation of Damage in Tendon Collagen That Is Enhanced with Aging*

    PubMed Central

    Thorpe, Chavaunne T.; Streeter, Ian; Pinchbeck, Gina L.; Goodship, Allen E.; Clegg, Peter D.; Birch, Helen L.

    2010-01-01

    Little is known about the rate at which protein turnover occurs in living tendon and whether the rate differs between tendons with different physiological roles. In this study, we have quantified the racemization of aspartic acid to calculate the age of the collagenous and non-collagenous components of the high strain injury-prone superficial digital flexor tendon (SDFT) and low strain rarely injured common digital extensor tendon (CDET) in a group of horses with a wide age range. In addition, the turnover of collagen was assessed indirectly by measuring the levels of collagen degradation markers (collagenase-generated neoepitope and cross-linked telopeptide of type I collagen). The fractional increase in d-Asp was similar (p = 0.7) in the SDFT (5.87 × 10−4/year) and CDET (5.82 × 10−4/year) tissue, and d/l-Asp ratios showed a good correlation with pentosidine levels. We calculated a mean (±S.E.) collagen half-life of 197.53 (±18.23) years for the SDFT, which increased significantly with horse age (p = 0.03) and was significantly (p < 0.001) higher than that for the CDET (34.03 (±3.39) years). Using similar calculations, the half-life of non-collagenous protein was 2.18 (±0.41) years in the SDFT and was significantly (p = 0.04) lower than the value of 3.51 (±0.51) years for the CDET. Collagen degradation markers were higher in the CDET and suggested an accumulation of partially degraded collagen within the matrix with aging in the SDFT. We propose that increased susceptibility to injury in older individuals results from an inability to remove partially degraded collagen from the matrix leading to reduced mechanical competence. PMID:20308077

  2. Mangroves in peril: unprecedented degradation rates of peri-urban mangroves in Kenya

    NASA Astrophysics Data System (ADS)

    Bosire, J. O.; Kaino, J. J.; Olagoke, A. O.; Mwihaki, L. M.; Ogendi, G. M.; Kairo, J. G.; Berger, U.; Macharia, D.

    2014-05-01

    Marine ecosystems are experiencing unprecedented degradation rates higher than any other ecosystem on the planet, which in some instances are up to 4 times those of rainforests. Mangrove ecosystems have especially been impacted by compounded anthropogenic pressures leading to significant cover reductions of between 35 and 50% (equivalent to 1-2% loss pa) for the last half century. The main objective of this study was to test the hypothesis that peri-urban mangroves suffering from compounded and intense pressures may be experiencing higher degradation rates than the global mean (and/or national mean for Kenya) using Mombasa mangroves (comprising Tudor and Mwache creeks) as a case study. Stratified sampling was used to sample along 22 and 10 belt transects in Mwache and Tudor respectively, set to capture stand heterogeneity in terms of species composition and structure in addition to perceived human pressure gradients using proximity to human habitations as a proxy. We acquired SPOT (HRV/ HRVIR/ HRS) images of April 1994, May 2000 and January 2009 and a vector mangrove map of 1992 at a scale of 1:50 000 for cover change and species composition analysis. Results from image classification of the 2009 image had 80.23% overall accuracy and Cohen's kappa of 0.77, thus proving satisfactory for use in this context. Structural data indicate that complexity index (CI) which captures stand structural development was higher in Mwache at 1.80 compared to Tudor at 1.71. From cover change data, Tudor lost 86.9% of the forest between 1992 and 2009, compared to Mwache at 45.4%, representing very high hitherto undocumented degradation rates of 5.1 and 2.7% pa, respectively. These unprecedentedly high degradation rates, which far exceed not only the national mean (for Kenya of 0.7% pa) but the global mean as well, strongly suggest that these mangroves are highly threatened due to compounded pressures. Strengthening of governance regimes through enforcement and compliance to halt

  3. Microbial degradation of 2,4-dichlorophenoxyacetic acid on the Greenland ice sheet.

    PubMed

    Stibal, Marek; Bælum, Jacob; Holben, William E; Sørensen, Sebastian R; Jensen, Anders; Jacobsen, Carsten S

    2012-08-01

    The Greenland ice sheet (GrIS) receives organic carbon (OC) of anthropogenic origin, including pesticides, from the atmosphere and/or local sources, and the fate of these compounds in the ice is currently unknown. The ability of supraglacial heterotrophic microbes to mineralize different types of OC is likely a significant factor determining the fate of anthropogenic OC on the ice sheet. Here we determine the potential of the microbial community from the surface of the GrIS to mineralize the widely used herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). Surface ice cores were collected and incubated for up to 529 days in microcosms simulating in situ conditions. Mineralization of side chain- and ring-labeled [(14)C]2,4-D was measured in the samples, and quantitative PCR targeting the tfdA genes in total DNA extracted from the ice after the experiment was performed. We show that the supraglacial microbial community on the GrIS contains microbes that are capable of degrading 2,4-D and that they are likely present in very low numbers. They can mineralize 2,4-D at a rate of up to 1 nmol per m(2) per day, equivalent to ∼26 ng C m(-2) day(-1). Thus, the GrIS should not be considered a mere reservoir of all atmospheric contaminants, as it is likely that some deposited compounds will be removed from the system via biodegradation processes before their potential release due to the accelerated melting of the ice sheet. PMID:22582066

  4. Regulation of Leaf Starch Degradation by Abscisic Acid Is Important for Osmotic Stress Tolerance in Plants[OPEN

    PubMed Central

    Thalmann, Matthias; Pazmino, Diana; Seung, David; Horrer, Daniel; Nigro, Arianna; Meier, Tiago; Zeeman, Samuel C.; Santelia, Diana

    2016-01-01

    Starch serves functions that range over a timescale of minutes to years, according to the cell type from which it is derived. In guard cells, starch is rapidly mobilized by the synergistic action of β-AMYLASE1 (BAM1) and α-AMYLASE3 (AMY3) to promote stomatal opening. In the leaves, starch typically accumulates gradually during the day and is degraded at night by BAM3 to support heterotrophic metabolism. During osmotic stress, starch is degraded in the light by stress-activated BAM1 to release sugar and sugar-derived osmolytes. Here, we report that AMY3 is also involved in stress-induced starch degradation. Recently isolated Arabidopsis thaliana amy3 bam1 double mutants are hypersensitive to osmotic stress, showing impaired root growth. amy3 bam1 plants close their stomata under osmotic stress at similar rates as the wild type but fail to mobilize starch in the leaves. 14C labeling showed that amy3 bam1 plants have reduced carbon export to the root, affecting osmolyte accumulation and root growth during stress. Using genetic approaches, we further demonstrate that abscisic acid controls the activity of BAM1 and AMY3 in leaves under osmotic stress through the AREB/ABF-SnRK2 kinase-signaling pathway. We propose that differential regulation and isoform subfunctionalization define starch-adaptive plasticity, ensuring an optimal carbon supply for continued growth under an ever-changing environment. PMID:27436713

  5. Novel Extracellular PHB Depolymerase from Streptomyces ascomycinicus: PHB Copolymers Degradation in Acidic Conditions

    PubMed Central

    García-Hidalgo, Javier; Hormigo, Daniel; Arroyo, Miguel; de la Mata, Isabel

    2013-01-01

    The ascomycin-producer strain Streptomyces ascomycinicus has been proven to be an extracellular poly(R)-3-hydroxybutyrate (PHB) degrader. The fkbU gene, encoding a PHB depolymerase (PhaZSa), has been cloned in E. coli and Rhodococcus sp. T104 strains for gene expression. Gram-positive host Rhodococcus sp. T104 was able to produce and secrete to the extracellular medium an active protein form. PhaZSa was purified by two hydrophobic interaction chromatographic steps, and afterwards was biochemically as well as structurally characterized. The enzyme was found to be a monomer with a molecular mass of 48.4 kDa, and displayed highest activity at 45°C and pH 6, thus being the first PHB depolymerase from a gram-positive bacterium presenting an acidic pH optimum. The PHB depolymerase activity of PhaZSa was increased in the presence of divalent cations due to non-essential activation, and also in the presence of methyl-β-cyclodextrin and PEG 3350. Protein structure was analyzed, revealing a globular shape with an alpha-beta hydrolase fold. The amino acids comprising the catalytic triad, Ser131-Asp209-His269, were identified by multiple sequence alignment, chemical modification of amino acids and site-directed mutagenesis. These structural results supported the proposal of a three-dimensional model for this depolymerase. PhaZSa was able to degrade PHB, but also demonstrated its ability to degrade films made of PHB, PHBV copolymers and a blend of PHB and starch (7∶3 proportion wt/wt). The features shown by PhaZSa make it an interesting candidate for industrial applications involving PHB degradation. PMID:23951224

  6. Degradation of emerging contaminants from water under natural sunlight: The effect of season, pH, humic acids and nitrate and identification of photodegradation by-products.

    PubMed

    Koumaki, Elena; Mamais, Daniel; Noutsopoulos, Constantinos; Nika, Maria-Christina; Bletsou, Anna A; Thomaidis, Nikolaos S; Eftaxias, Alexander; Stratogianni, Georgia

    2015-11-01

    Both photodegradation and hydrolysis of non-steroidal anti-inflammatory drugs (NSAIDs) and endocrine disrupting chemicals (EDCs) were investigated in order to evaluate their photochemical fate in aquatic environment and to assess the effect of season and specific characteristics of water (pH, humic acids and nitrate concentration) on the removal of target EDCs and NSAIDs through photodegradation. An additional objective was the identification of the photodegradation by-products of specific NSAIDs and their dependence on irradiation time. Selected compounds' transformation was investigated under natural sunlight radiation while control experiments were conducted in the dark. As expected, most of compounds' degradation rate decreased with decreasing light intensity between two different experimental periods. Most of the tested compounds exhibited different rates of degradation during direct and indirect photolysis. The degradation rate of the selected compounds increased in the presence of NO3(-) and the photodegradation rate was higher for some compounds in alkaline than in acidic solution. The effect of humic acids' presence in the water depends on the absorbance spectrum of the compound and the produced photosensitizers. More specifically, humic acids act as inner filter toward most of the selected NSAIDs and as photosensitizers toward most of the EDCs. The results of the irradiation experiments in the presence of both humic acids and NO3(-), indicate that the direct photolysis is much more efficient than indirect photochemical processes. Finally, several degradation by-products of ketoprofen and diclofenac were identified in the samples, exposed to sunlight. The dependence of these by-products on radiation time is also demonstrated. PMID:26246277

  7. Ab Initio Molecular Dynamics Simulations of ..beta..-D-Glucose and ..beta..-D-Xylose Degradation Mechanisms in Acidic Aqueous Solution

    SciTech Connect

    Qian, X.; Nimlos, M. R.; Davis, M.; Johnson, D. K.; Himmel, M. E.

    2005-01-01

    Ab initio molecular dynamics simulations were employed to investigate, with explicit solvent water molecules, {beta}-d-glucose and {beta}-d-xylose degradation mechanisms in acidic media. The rate-limiting step in sugar degradation was found to be protonation of the hydroxyl groups on the sugar ring. We found that the structure of water molecules plays a significant role in the acidic sugar degradation pathways. Firstly, a water molecule competes with the hydroxyl group on the sugar ring for protons. Secondly, water forms hydrogen bonds with the hydroxyl groups on the sugar rings, thus weakening the C-C and C-O bonds (each to a different degree). Note that the reaction pathways could be altered due to the change of relative stability of the C-C and C-O bonds. Thirdly, water molecules that are hydrogen-bonded to sugar hydroxyls could easily extract a proton from the reaction intermediate, terminating the reaction. Indeed, the sugar degradation pathway is complex due to multiple protonation probabilities and the surrounding water structure. Our experimental data support multiple sugar acidic degradation pathways.

  8. Effect of acidic solutions on the surface degradation of a micro-hybrid composite resin.

    PubMed

    Münchow, Eliseu A; Ferreira, Ana Cláudia A; Machado, Raissa M M; Ramos, Tatiana S; Rodrigues-Junior, Sinval A; Zanchi, Cesar H

    2014-01-01

    Composite resins may undergo wear by the action of chemical substances (e.g., saliva, alcohol, bacterial acids) of the oral environment, which may affect the material's structure and surface properties. This study evaluated the effect of acidic substances on the surface properties of a micro-hybrid composite resin (Filtek Z-250). Eighty specimens were prepared, and baseline hardness and surface roughness (KMN0 and Ra0, respectively) were measured. The specimens were subjected to sorption (SO) and solubility (SL) tests according to ISO 4049:2009, but using different storage solutions: deionized water; 75/25 vol% ethanol/water solution; lactic acid; propionic acid; and acetic acid. The acids were used in two concentrations: PA and 0.02 N. pH was measured for all solutions and final hardness (KMN1) and surface roughness (Ra1) were measured. Data were analyzed with paired t-tests and one-way ANOVA and Tukey's test (a=5%). All solutions decreased hardness and increased the Ra values, except for the specimens stored in water and 0.02 N lactic acid, which maintained the hardness. All solutions produced similar SO and SL phenomena, except for the 0.02 N lactic acid, which caused lower solubility than the other solutions. Ethanol showed the highest pH (6.6) and the 0.02 N lactic acid the lowest one (2.5). The solutions affected negatively the surface properties of the composite resin; in addition, an acidic pH did not seem to be a significant factor that intensifies the surface degradation phenomena. PMID:25250496

  9. Varying relative degradation rates of oil in different forms and environments revealed by ramped pyrolysis.

    PubMed

    Pendergraft, Matthew A; Rosenheim, Brad E

    2014-09-16

    Degradation of oil contamination yields stabilized products by removing and transforming reactive and volatile compounds. In contaminated coastal environments, the processes of degradation are influenced by shoreline energy, which increases the surface area of the oil as well as exchange between oil, water, sediments, microbes, oxygen, and nutrients. Here, a ramped pyrolysis carbon isotope technique is employed to investigate thermochemical and isotopic changes in organic material from coastal environments contaminated with oil from the 2010 BP Deepwater Horizon oil spill. Oiled beach sediment, tar ball, and marsh samples were collected from a barrier island and a brackish marsh in southeast Louisiana over a period of 881 days. Stable carbon ((13)C) and radiocarbon ((14)C) isotopic data demonstrate a predominance of oil-derived carbon in the organic material. Ramped pyrolysis profiles indicate that the organic material was transformed into more stable forms. Our data indicate relative rates of stabilization in the following order, from fastest to slowest: high energy beach sediments > low energy beach sediments > marsh > tar balls. Oil was transformed most rapidly where shoreline energy and the rates of oil dispersion and exchange with water, sediments, microbes, oxygen, and nutrients were greatest. Still, isotope data reveal persistence of oil. PMID:25105342

  10. Improvement of the detection rate in digital watermarked images against image degradation caused by image processing

    NASA Astrophysics Data System (ADS)

    Nishio, Masato; Ando, Yutaka; Tsukamoto, Nobuhiro; Kawashima, Hironao; Nakamura, Shinya

    2004-04-01

    In the current environment of medical information disclosure, the general-purpose image format such as JPEG/BMP which does not require special software for viewing, is suitable for carrying and managing medical image information individually. These formats have no way to know patient and study information. We have therefore developed two kinds of ID embedding methods: one is Bit-swapping method for embedding Alteration detection ID and the other is data-imposing method in Fourier domain using Discrete Cosine Transform (DCT) for embedding Original image source ID. We then applied these two digital watermark methods to four modality images (Chest X-ray, Head CT, Abdomen CT, Bone scintigraphy). However, there were some cases where the digital watermarked ID could not be detected correctly due to image degradation caused by image processing. In this study, we improved the detection rate in digital watermarked image using several techniques, which are Error correction method, Majority correction method, and Scramble location method. We applied these techniques to digital watermarked images against image processing (Smoothing) and evaluated the effectiveness. As a result, Majority correction method is effective to improve the detection rate in digital watermarked image against image degradation.

  11. Effect of Boric Acid on Volatile Products of Thermooxidative Degradation of Epoxy Polymers

    NASA Astrophysics Data System (ADS)

    Nazarenko, O. B.; Bukhareva, P. B.; Melnikova, T. V.; Visakh, P. M.

    2016-01-01

    The polymeric materials are characterized by high flammability. The use of flame retardants in order to reduce the flammability of polymers can lead to the formation of toxic gaseous products under fire conditions. In this work we studied the effect of boric acid on the volatile products of thermooxidative degradation of epoxy polymers. The comparative investigations were carried out on the samples of the unfilled epoxy resin and epoxy resin filled with a boric acid at percentage 10 wt. %. The analysis of the volatile decomposition products and thermal stability of the samples under heating in an oxidizing medium was performed using a thermal mass-spectrometric analysis. It is found that the incorporation of boric acid into the polymer matrix increases the thermal stability of epoxy composites and leads to a reduction in the 2-2.7 times of toxic gaseous products

  12. Solid supported in situ derivatization extraction of acidic degradation products of nerve agents from aqueous samples.

    PubMed

    Chinthakindi, Sridhar; Purohit, Ajay; Singh, Varoon; Tak, Vijay; Dubey, D K; Pardasani, Deepak

    2014-09-12

    This study deals with the solid supported in situ derivatization extraction of acidic degradation products of nerve agents present in aqueous samples. Target analytes were alkyl alkylphosphonic acids and alkylphosphonic acids, which are important environmental signatures of nerve agents. The method involved tert-butyldimethylchlorosilane mediated in situ silylation of analytes on commercially available diatomaceous solid phase extraction cartridges. Various parameters such as derivatizing reagent, its concentration, reaction time, temperature and eluting solvent were optimized. Recoveries of the analytes were determined by GC-MS which ranged from 60% to 86%. The limits of detection (LOD) and limit of quantification (LOQ) with selected analytes were achieved down to 78 and 213ngmL(-1) respectively, in selected ion monitoring mode. The successful applicability of method was also demonstrated on samples of biological origin such as plasma and to the samples received in 34th official proficiency test conducted by the Organization for Prohibition the of Chemical Weapons. PMID:25103280

  13. Quantitative detection of syntrophic fatty acid-degrading bacterial communities in methanogenic environments.

    PubMed

    Mathai, Prince P; Zitomer, Daniel H; Maki, James S

    2015-06-01

    In methanogenic habitats, volatile fatty acids (VFA), such as propionate and butyrate, are major intermediates in organic matter degradation. VFA are further metabolized to H(2), acetate and CO(2) by syntrophic fatty acid-degrading bacteria (SFAB) in association with methanogenic archaea. Despite their indispensable role in VFA degradation, little is known about SFAB abundance and their environmental distribution. To facilitate ecological studies, we developed four novel genus-specific quantitative PCR (qPCR) assays, with primer sets targeting known SFAB: Syntrophobacter, Smithella, Pelotomaculum and Syntrophomonas. Primer set specificity was confirmed using in silico and experimental (target controls, clone libraries and melt-curve analysis) approaches. These qPCR assays were applied to quantify SFAB in a variety of mesophilic methanogenic habitats, including a laboratory propionate enrichment culture, pilot- and full-scale anaerobic reactors, cow rumen, horse faeces, an experimental rice paddy soil, a bog stream and swamp sediments. The highest SFAB 16S rRNA gene copy numbers were found in the propionate enrichment culture and anaerobic reactors, followed by the bog stream and swamp sediment samples. In addition, it was observed that SFAB and methanogen abundance varied with reactor configuration and substrate identity. To our knowledge, this research represents the first comprehensive study to quantify SFAB in methanogenic habitats using qPCR-based methods. These molecular tools will help investigators better understand syntrophic microbial communities in engineered and natural environments. PMID:25814038

  14. Detection of chlorodifluoroacetic acid in precipitation: A possible product of fluorocarbon degradation

    SciTech Connect

    Martin, J.W.; Franklin, J.; Hanson, M.L.; Solomon, K.R.; Mabury, S.A.; Ellis, D.A.; Scott, B.F.; Muri, D.C.G.

    2000-01-15

    Chlorodiffluoroacetic acid (CDFA) was detected in rain and snow samples from various regions of Canada. Routine quantitative analysis was performed using an in-situ derivatization technique that allowed for the determination of CDFA by GC-MS of the anilide derivative. Validation of environmental CDFA was provided by strong anionic exchange chromatography and detection by {sup 19}F NMR. CDFA concentrations ranges from <7.1 to 170 ng L{sup {minus}1} among all samples analyzed. Monthly volume-weighted CDFA concentrations ranged from <7.1 to 170 ng L{sup {minus}1} among all samples analyzed. Monthly volume-weighted CDFA concentrations in rain event samples showed a seasonal trend between June and November 1998, peaking in late summer and decreasing in the fall for Guelph and Toronto sites. Preliminary toxicity tests with the aquatic macrophytes Myriophyllum sibiricum and Myriophyllum spicatum suggest that CDFA does not represent a risk of acute toxicity to these aquatic macrophytes at current environmental concentrations. A degradation study suggests that CDFA is recalcitrant to biotic and abiotic degradation relative to dichloroacetic acid (DCA) and may accumulate in the aquatic environment. On the basis of existing experimental data, the authors postulate that CDFA is a degradation product of CFC-113 and, to a lesser extent, HCFC-142b. If CFC-113 is a source, its ozone depletion potential may be lower than previously assumed. Further work is required to identify alternative atmospheric and terrestrial sources of CDFA.

  15. Hyaluronic acid hydrogel scaffolds with a triple degradation behavior for bone tissue engineering.

    PubMed

    Cui, Ning; Qian, Junmin; Liu, Ting; Zhao, Na; Wang, Hongjie

    2015-08-01

    In this study, in order to better mimick the nature of bone extracellular matrix, hyaluronic acid (HA) hydrogels having a triple degradation behavior were synthesized from 3,3'-dithiodipropionate hydrazide-modified HA (DTPH-HA) and polyethylene glycol dilevulinate (LEV-PEG-LEV) via the reaction of the ketone carbonyl groups of LEV-PEG-LEV with the hydrazide groups of DTPH-HA. The HA hydrogels were characterized by solid state (13)C NMR, FT-IR, SEM, and rheological, swelling and degradation tests. The results showed that the HA hydrogels exhibited a highly porous morphology and had pore diameters ranging from 20 to 200 μm. The equilibrium swelling ratio of the HA hydrogels was no less than 37.5. The HA hydrogels could be degraded by hyaluronidase and reducing substances or at acidic pH values. The biocompatibility of the HA hydrogels was evaluated using osteoblast-like MC3T3-E1 cells by live/dead staining and MTT assays. The results revealed that the HA hydrogels had good biocompatibility and could support the attachment and proliferation of MC3T3-E1 cells. All the results indicated that the HA hydrogels synthesized by hydrazone bond crosslinking might have great potential to be used in bone tissue engineering. PMID:25933539

  16. Amyloid Plaque-Associated Oxidative Degradation of Uniformly Radiolabeled Arachidonic Acid.

    PubMed

    Furman, Ran; Murray, Ian V J; Schall, Hayley E; Liu, Qiwei; Ghiwot, Yonatan; Axelsen, Paul H

    2016-03-16

    Oxidative stress is a frequently observed feature of Alzheimer's disease, but its pathological significance is not understood. To explore the relationship between oxidative stress and amyloid plaques, uniformly radiolabeled arachidonate was introduced into transgenic mouse models of Alzheimer's disease via intracerebroventricular injection. Uniform labeling with carbon-14 is used here for the first time, and made possible meaningful quantification of arachidonate oxidative degradation products. The injected arachidonate entered a fatty acid pool that was subject to oxidative degradation in both transgenic and wild-type animals. However, the extent of its degradation was markedly greater in the hippocampus of transgenic animals where amyloid plaques were abundant. In human Alzheimer's brain, plaque-associated proteins were post-translationally modified by hydroxynonenal, a well-known oxidative degradation product of arachidonate. These results suggest that several recurring themes in Alzheimer's pathogenesis, amyloid β proteins, transition metal ions, oxidative stress, and apolipoprotein isoforms, may be involved in a common mechanism that has the potential to explain both neuronal loss and fibril formation in this disease. PMID:26800372

  17. Oxidative degradation of nalidixic acid by nano-magnetite via Fe2+/O2-mediated reactions.

    PubMed

    Ardo, Sandy G; Nélieu, Sylvie; Ona-Nguema, Georges; Delarue, Ghislaine; Brest, Jessica; Pironin, Elsa; Morin, Guillaume

    2015-04-01

    Organic pollution has become a critical issue worldwide due to the increasing input and persistence of organic compounds in the environment. Iron minerals are potentially able to degrade efficiently organic pollutants sorbed to their surfaces via oxidative or reductive transformation processes. Here, we explored the oxidative capacity of nano-magnetite (Fe3O4) having ∼ 12 nm particle size, to promote heterogeneous Fenton-like reactions for the removal of nalidixic acid (NAL), a recalcitrant quinolone antibacterial agent. Results show that NAL was adsorbed at the surface of magnetite and was efficiently degraded under oxic conditions. Nearly 60% of this organic contaminant was eliminated after 30 min exposure to air bubbling in solution in the presence of an excess of nano-magnetite. X-ray diffraction (XRD) and Fe K-edge X-ray absorption spectroscopy (XANES and EXAFS) showed a partial oxidation of magnetite to maghemite during the reaction, and four byproducts of NAL were identified by liquid chromatography-mass spectroscopy (UHPLC-MS/MS). We also provide evidence that hydroxyl radicals (HO(•)) were involved in the oxidative degradation of NAL, as indicated by the quenching of the degradation reaction in the presence of ethanol. This study points out the promising potentialities of mixed valence iron oxides for the treatment of soils and wastewater contaminated by organic pollutants. PMID:25756496

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

    PubMed

    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

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

    SciTech Connect

    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.

  20. Formic acid enhanced effective degradation of methyl orange dye in aqueous solutions under UV-Vis irradiation.

    PubMed

    Wang, Jingjing; Bai, Renbi

    2016-09-15

    Developing efficient technologies to treat recalcitrant organic dye wastewater has long been of great research and practical interest. In this study, a small molecule, formic acid (FA), was applied as a process enhancer for the degradation of methyl orange (MO) dye as a model recalcitrant organic pollutant in aqueous solutions under the condition of UV-Vis light irradiation and air aeration at the ambient temperature of 25 °C. It was found that the decolouration of the dye solutions can be rapidly achieved, reducing the time, for example, from around 17.6 h without FA to mostly about less than 2 h with the presence of FA. The mineralization rate of MO dye reached as high as 81.8% in 1.5 h in the case of initial MO dye concentration at 25 mg L(-1), which is in contrast to nearly no mineralization of the MO dye for a similar system without the FA added. The study revealed that the generation of the H2O2 species in the system was enhanced and the produced OH radicals effectively contributed to the degradation of the MO dye. Process parameters such as the initial concentration of MO dye, FA dosage and solution pH were all found to have some effect on the degradation efficiency under the same condition of UV-Vis light irradiation and air aeration. The MO dye degradation performance was found to follow a first-order reaction rate to the MO dye concentration in most cases and there existed a positive correlation between the reaction rate constant and the initial FA concentration. Compared to the traditional H2O2/UV-Vis oxidation system, the use of FA as a process-enhancing agent can have the advantages of low cost, easy availability, and safe to use. The study hence demonstrates a promising approach to use a readily available small molecule of FA to enhance the degradation of recalcitrant organic pollutants, such as MO dye, especially for their pre-treatment. PMID:27258621

  1. Laboratory photochemical processing of aqueous aerosols: formation and degradation of dicarboxylic acids, oxocarboxylic acids and α-dicarbonyls

    NASA Astrophysics Data System (ADS)

    Pavuluri, C. M.; Kawamura, K.; Mihalopoulos, N.; Swaminathan, T.

    2015-07-01

    To better understand the photochemical processing of dicarboxylic acids and related polar compounds, we conducted batch UV irradiation experiments on two types of aerosol samples collected from India, which represent anthropogenic (AA) and biogenic (BA) aerosols, for time periods of 0.5 to 120 h. The irradiated samples were analyzed for molecular compositions of diacids, oxoacids and α-dicarbonyls. The results show that photochemical degradation of oxalic (C2), malonic (C3) and other C8-C12 diacids overwhelmed their production in aqueous aerosols, whereas succinic acid (C4) and C5-C7 diacids showed a significant increase (ca. 10 times) during the course of irradiation experiments. The photochemical formation of oxoacids and α-dicarbonyls overwhelmed their degradation during the early stages of experiment except for ω-oxooctanoic acid (ωC8), which showed a similar pattern to that of C4. We also found a gradual decrease in the relative abundance of C2 to total diacids and an increase in the relative abundance of C4 during prolonged experiment. Based on the changes in concentrations and mass ratios of selected species with the irradiation time, we hypothesize that iron-catalyzed photolysis of C2 and C3 diacids controls their concentrations in Fe-rich atmospheric waters, whereas photochemical formation of C4 diacid (via ωC8) is enhanced with photochemical processing of aqueous aerosols in the atmosphere. This study demonstrates that the ambient aerosols contain abundant precursors that produce diacids, oxoacids and α-dicarbonyls, although some species such as oxalic acid decompose extensively during an early stage of photochemical processing.

  2. Separation and determination of degradation products of acid orange 7 by capillary electrophoresis/capacitively coupled contactless conductivity detector.

    PubMed

    Wang, Xin; Xiong, Ya; Xie, Tianyao; Sharma, Virender K; Tu, Yuting; Yang, Jiannan; Tian, Shuanghong; He, Chun

    2013-07-15

    Capillary electrophoresis (CE) with capacitively coupled contactless conductivity detector (C(4)D) was developed to separate azo-dyestuff acid orange 7 (AO7) and its six degradation products. The analyzed products were sulfamic acid, oxalic acid, benzenesulfonic acid, 4-hydroxybenzene sulfonic acid, phthalic acid, and 4-aminobenzene sulfonic acid. In developing the method, types and concentrations of running buffers, injecting voltage and time, and applied voltage were tested to obtain optimum conditions to analyze target compounds. The separation was successfully achieved within 10 min using a fused-silica capillary under the following conditions: 20 mmol L(-1) acetate acid buffer, electrokinetic injection of -12 kV × 10 s, and applied voltage of -13 kV. The developed method was applied to analyze degradation products in situ during the reaction of AO7 with Fenton reagent (Fe(II)+H2O2 at pH 4.0). PMID:23622525

  3. A second pathway to degrade pyrimidine nucleic acid precursors in eukaryotes.

    PubMed

    Andersen, Gorm; Björnberg, Olof; Polakova, Silvia; Pynyaha, Yuriy; Rasmussen, Anna; Møller, Kasper; Hofer, Anders; Moritz, Thomas; Sandrini, Michael Paolo Bastner; Merico, Anna-Maria; Compagno, Concetta; Akerlund, Hans-Erik; Gojković, Zoran; Piskur, Jure

    2008-07-18

    Pyrimidine bases are the central precursors for RNA and DNA, and their intracellular pools are determined by de novo, salvage and catabolic pathways. In eukaryotes, degradation of uracil has been believed to proceed only via the reduction to dihydrouracil. Using a yeast model, Saccharomyces kluyveri, we show that during degradation, uracil is not reduced to dihydrouracil. Six loci, named URC1-6 (for uracil catabolism), are involved in the novel catabolic pathway. Four of them, URC3,5, URC6, and URC2 encode urea amidolyase, uracil phosphoribosyltransferase, and a putative transcription factor, respectively. The gene products of URC1 and URC4 are highly conserved proteins with so far unknown functions and they are present in a variety of prokaryotes and fungi. In bacteria and in some fungi, URC1 and URC4 are linked on the genome together with the gene for uracil phosphoribosyltransferase (URC6). Urc1p and Urc4p are therefore likely the core components of this novel biochemical pathway. A combination of genetic and analytical chemistry methods demonstrates that uridine monophosphate and urea are intermediates, and 3-hydroxypropionic acid, ammonia and carbon dioxide the final products of degradation. The URC pathway does not require the presence of an active respiratory chain and is therefore different from the oxidative and rut pathways described in prokaryotes, although the latter also gives 3-hydroxypropionic acid as the end product. The genes of the URC pathway are not homologous to any of the eukaryotic or prokaryotic genes involved in pyrimidine degradation described to date. PMID:18550080

  4. Optimization of acidic fibroblast growth factor (FGF-1) and its delivery through a modified degradable fibrin scaffold

    NASA Astrophysics Data System (ADS)

    Pandit, Abhay Smashikant

    The aim of this investigation was to develop a degradable fibrin wound dressing that can deliver an optimized dose of acidic fibroblast growth factor (FGF-1). This aim led to three distinct phases of study. In the first phase, a structurally modified fibrin degradable scaffold was developed and tested in a rabbit ear ulcer model. A significant increase in the angiogenic and fibroblastic response with a corresponding decrease in healing time was seen in the modified fibrin-treated ulcers as compared with untreated ulcers and ulcers treated with non-modified fibrin systems. In the second phase of the study, a biochemical factor, FGF-1, was added to this scaffold. An optimal dose of 8 mug of FGF-1 was determined to be required to initiate a desired wound-healing response in a rabbit ear ulcer model, based on an enhanced angiogenic and fibroblastic response and an increased epithelialization rate. The objective of the last phase was to investigate the efficacy of a modified scaffold as a vehicle for FGF-1. In vivo testing was conducted in a full-thickness defect model in a rabbit. Improvements were seen in the angiogenic and fibroblastic responses in the FGF-1/modified fibrin treatment group and, hence, FGF-1/modified fibrin was the preferred treatment. In conclusion, the modified fibrin/FGF-1 matrix served as a suitable vehicle for the growth factor, providing a desired healing response and a desirable release rate and, thus, was determined to be an effective scaffold.

  5. Preparation and characterization of guluronic acid oligosaccharides degraded by a rapid microwave irradiation method.

    PubMed

    Hu, Ting; Li, Chunxia; Zhao, Xia; Li, Guangsheng; Yu, Guangli; Guan, Huashi

    2013-05-24

    Guluronic acid oligosaccharides (GOS) with degree of polymerization (DP) ranging from 1 to 10 were prepared by a rapid microwave degradation method. Polyguluronic acid, fractionated from alginate hydrolysate, was dissolved in dilute ammonia water at a concentration of 20 mg/mL (pH 5) and then hydrolyzed under microwave irradiation (1600 W) at 130°C for 15 min to produce GOS mixture. The GOS mixture was separated by a Bio-Gel P6 column and ten fractions were obtained. Each GOS fraction was further characterized by electrospray ionization mass spectrometry, (1)H NMR, (13)C NMR, and 2D NMR spectroscopy techniques. The data showed that the GOS fractions were saturated oligoguluronates with general molecular formula C(6n)H(8n+2)O(6n+1) (n=1-10). This microwave degradation method was not only convenient, less time consuming, and environment-friendly, but also produced GOS with high yield (71%) and eliminating a desalting procedure compared to conventional acid hydrolysis method. PMID:23584235

  6. Reduction Rates for Higher Americium Oxidation States in Nitric Acid

    SciTech Connect

    Grimes, Travis Shane; Mincher, Bruce Jay; Schmitt, Nicholas C

    2015-09-30

    The stability of hexavalent americium was measured using multiple americium concentrations and nitric acid concentrations after contact with the strong oxidant sodium bismuthate. Contrary to our hypotheses Am(VI) was not reduced faster at higher americium concentrations, and the reduction was only zero-order at short time scales. Attempts to model the reduction kinetics using zero order kinetic models showed Am(VI) reduction in nitric acid is more complex than the autoreduction processes reported by others in perchloric acid. The classical zero-order reduction of Am(VI) was found here only for short times on the order of a few hours. We did show that the rate of Am(V) production was less than the rate of Am(VI) reduction, indicating that some Am(VI) undergoes two electron-reduction to Am(IV). We also monitored the Am(VI) reduction in contact with the organic diluent dodecane. A direct comparison of these results with those in the absence of the organic diluent showed the reduction rates for Am(VI) were not statistically different for both systems. Additional americium oxidations conducted in the presence of Ce(IV)/Ce(III) ions showed that Am(VI) is reduced without the typical growth of Am(V) observed in the systems sans Ce ion. This was an interesting result which suggests a potential new reduction/oxidation pathway for Am in the presence of Ce; however, these results were very preliminary, and will require additional experiments to understand the mechanism by which this occurs. Overall, these studies have shown that hexavalent americium is fundamentally stable enough in nitric acid to run a separations process. However, the complicated nature of the reduction pathways based on the system components is far from being rigorously understood.

  7. Load-bearing capacity and biological allowable limit of biodegradable metal based on degradation rate in vivo.

    PubMed

    Cho, Sung Youn; Chae, Soo-Won; Choi, Kui Won; Seok, Hyun Kwang; Han, Hyung Seop; Yang, Seok Jo; Kim, Young Yul; Kim, Jong Tac; Jung, Jae Young; Assad, Michel

    2012-08-01

    In this study, a newly developed Mg-Ca-Zn alloy for low degradation rate and surface erosion properties was evaluated. The compressive, tensile, and fatigue strength were measured before implantation. The degradation behavior was evaluated by analyzing the microstructure and local hardness of the explanted specimen. Mean and maximum degradation rates were measured using micro CT equipment from 4-, 8-, and 16- week explants, and the alloy was shown to display surface erosion properties. Based on these characteristics, the average and minimum load bearing capacities in tension, compression, and bending modes were calculated. According to the degradation rate and references of recommended dietary intakes (RDI), the Mg-Ca-Zn alloy appears to be safe for human use. PMID:22689439

  8. Evaluation of reversible and irreversible degradation rates of polymer electrolyte membrane fuel cells tested in automotive conditions

    NASA Astrophysics Data System (ADS)

    Gazdzick, Pawel; Mitzel, Jens; Garcia Sanchez, Daniel; Schulze, Mathias; Friedrich, K. Andreas

    2016-09-01

    This work provides single cell durability tests of membrane electrode assemblies in dynamic operation regularly interrupted by recovery procedures for the removal of reversible voltage losses. Degradation rates at different loads in one single test can be determined from these tests. Hence, it is possible to report degradation rates versus current density instead of a single degradation rate value. A clear discrimination between reversible and irreversible voltage loss rates is provided. The irreversible degradation rate can be described by a linear regression of voltage values after the recovery steps. Using voltage values before refresh is less adequate due to possible impacts of reversible effects. The reversible contribution to the voltage decay is dominated by an exponential decay after restart, eventually turning into a linear one. A linear-exponential function is proposed to fit the reversible voltage degradation. Due to this function, the degradation behavior of an automotive fuel cell can be described correctly during the first hours after restart. The fit parameters decay constant, exponential amplitude and linear slope are evaluated. Eventually, the reasons for the voltage recovery during shutdown are analyzed showing that ionomer effects in the catalyst layer and/or membrane seem to be the key factor in this process.

  9. Diversity in growth and protein degradation by dairy relevant lactic acid bacteria species in reconstituted whey.

    PubMed

    Pescuma, Micaela; Hébert, Elvira M; Bru, Elena; Font de Valdez, Graciela; Mozzi, Fernanda

    2012-05-01

    The high nutritional value of whey makes it an interesting substrate for the development of fermented foods. The aim of this work was to evaluate the growth and proteolytic activity of sixty-four strains of lactic acid bacteria in whey to further formulate a starter culture for the development of fermented whey-based beverages. Fermentations were performed at 37 °C for 24 h in 10 and 16% (w/v) reconstituted whey powder. Cultivable populations, pH, and proteolytic activity (o-phthaldialdehyde test) were determined at 6 and 24 h incubation. Hydrolysis of whey proteins was analysed by Tricine SDS-PAGE. A principal component analysis (PCA) was applied to evaluate the behaviour of strains. Forty-six percent of the strains grew between 1 and 2 Δlog CFU/ml while 19% grew less than 0·9 Δlog CFU/ml in both reconstituted whey solutions. Regarding the proteolytic activity, most of the lactobacilli released amino acids and small peptides during the first 6 h incubation while streptococci consumed the amino acids initially present in whey to sustain growth. Whey proteins were degraded by the studied strains although to different extents. Special attention was paid to the main allergenic whey protein, β-lactoglobulin, which was degraded the most by Lactobacillus acidophilus CRL 636 and Lb. delbrueckii subsp. bulgaricus CRL 656. The strain variability observed and the PCA applied in this study allowed selecting appropriate strains able to improve the nutritional characteristics (through amino group release and protein degradation) and storage (decrease in pH) of whey. PMID:22559062

  10. Composition, assimilation and degradation of Phaeocystis globosa-derived fatty acids in the North Sea

    NASA Astrophysics Data System (ADS)

    Hamm, Christian E.; Rousseau, Veronique

    2003-12-01

    The fate of a Phaeocystis globosa bloom in the southern North Sea off Belgium, the Netherlands and Germany in May 1995 was investigated during a cruise with RV 'Belgica'. We used fatty acids as biomarkers to follow the fate of Phaeocystis-derived biomass of a Phaeocystis-dominated spring bloom. The bloom, in which up to >99% of the biomass was contributed by Phaeocystis, showed a fatty acid composition with a characteristically high abundance of polyunsaturated C 18-fatty acids, which increased in concentration with number of double bonds up to 18:5 (n-3), and high concentrations of 20:5 (n-3) and 22:6 (n-3). In contrast to most previous studies, fatty acid analysis of the mesozooplankton community (mainly calanoid copepods) and meroplankton ( Carcinus maenas megalope) indicated that P. globosa was a major component (ca. 70% and 50%, respectively) in the diet of these organisms. Massive accumulations of amorphous grey aggregates, in which Phaeocystis colonies were major components, were dominated by saturated fatty acids and contained only few of the polyunsaturated C 18-fatty acids. A hydrophobic surface slick that covered the water surface during the bloom showed very similar patterns. Foam patches contained few Phaeocystis-typical fatty acids, but increased amounts of diatom-typical compounds such as 16:1 (n-7) and 20:5 (n-3), and 38% fatty alcohols, indicating that wax esters dominated the lipid fraction in the foam with ca. 76% (w/w). The fatty acid compositions of surface sediment showed that no sedimentation of fresh Phaeocystis occurred during the study. The results indicate that Phaeocystis-derived organic matter degraded while floating or in suspension, and had not reached the sediment in substantial amounts.

  11. Interspecies distances between propionic acid degraders and methanogens in syntrophic consortia for optimal hydrogen transfer.

    PubMed

    Felchner-Zwirello, Monika; Winter, Josef; Gallert, Claudia

    2013-10-01

    A mixed culture from an anaerobic biowaste digester was enriched on propionate and used to investigate interspecies hydrogen transfer in dependence of spatial distances between propionate degraders and methanogens. From 20.3 mM propionate, 20.8 mM acetate and 15.5 mM methane were formed. Maximum specific propionate oxidation and methane formation rates were 49 and 23 mmol mg(-1) day(-1), respectively. Propionate oxidation was inhibited by only 20 mM acetate by about 50 %. Intermediate formate formation during inhibited methanogensis was observed. The spatial distribution and the biovolume fraction of propionate degraders and of methanogens in relation to the total population during aggregate formation were determined. Measurements of interbacterial distances were conducted with fluorescence in situ hybridization by application of group-specific 16S rRNA-targeted probes and 3D image analyses. With increasing incubation time, floc formation and growth up to 54 μm were observed. Propionate degraders and methanogens were distributed randomly in the flocs. The methanogenic biovolume fraction was high at the beginning and remained constant over 42 days, whereas the fraction of propionate degraders increased with time during propionate feeding. Interbacterial distances between propionate degraders and methanogens decreased with time from 5.30 to 0.29 μm, causing an increase of the maximum possible hydrogen flux from 1.1 to 10.3 nmol ml(-1) min(-1). The maximum possible hydrogen flux was always higher than the hydrogen formation and consumption rate, indicating that reducing the interspecies distance by aggregation is advantageous in complex ecosystems. PMID:23233207

  12. Laboratory degradation rates of 11 pyrethroids under aerobic and anaerobic conditions.

    PubMed

    Meyer, Brian N; Lam, Chung; Moore, Sean; Jones, Russell L

    2013-05-22

    Degradation of 11 pyrethroids was measured over approximately 100 days in three sediment/water systems under aerobic and anaerobic conditions at 25 °C in the dark. The three California sediments represented a range of textures and organic matter. Test compounds were bifenthrin, cypermethrin, ζ-cypermethrin, cyfluthrin, β-cyfluthrin, deltamethrin, esfenvalerate, fenpropathrin, γ-cyhalothrin, λ-cyhalothrin, and permethrin. A non-standard design was employed to keep conditions essentially the same for all compounds. The test compounds were applied as two test mixtures (six active ingredients per mixture, with bifenthrin common to both) at approximately 50 μg of test compound/kg of sediment (dry weight). Extracts of sediment/water were cleaned up by solid-phase extraction, concentrated, and analyzed by gas chromatography/mass spectrometry (except deltamethrin) against matrix-matched standards, with cyfluthrin-d6 as an internal standard. Deltamethrin was analyzed by liquid chromatography/tandem mass spectrometry using deltamethrin-phenoxy-(13)C6 as an internal standard. Similar degradation rates of bifenthrin and for related isomeric compounds (e.g., cyfluthrin and β-cyfluthrin) were generally measured in both mixtures for each sediment. First-order half-lives under aerobic conditions ranged from 2.9 to greater than 200 days, with a median value of 18 days. Under anaerobic conditions, the range was from 20 to greater than 200 days, with a median value of 70 days. PMID:23641910

  13. Microbial degradation of chelating agents used in detergents with special reference to nitrilotriacetic acid (NTA).

    PubMed

    Egli, T; Bally, M; Uetz, T

    1990-01-01

    The extensive use of phosphate-based detergents and agricultural fertilizers is one of the main causes of the world-wide eutrophication of rivers and lakes. To ameliorate such problems partial or total substitution of phosphates in laundry detergents by synthetic, non-phosphorus containing complexing agents is practiced in several countries. The physiological, biochemical and ecological aspects of the microbial degradation of the complexing agents most frequently used, such as polyphosphates, aminopolycarboxylates (especially of nitrilotriacetic acid), and phosphonates are reviewed. PMID:1368145

  14. Effects of starvation for potassium and other inorganic ions on protein degradation and ribonucleic acid synthesis in Escherichia coli.

    PubMed

    St John, A C; Goldberg, A L

    1980-09-01

    Starvation of Escherichia coli for potassium, phosphate, or magnesium ions leads to a reversible increase in the rate of protein degradation and an inhibition of ribonucleic acid (RNA) synthesis. In cells deprived of potassium, the breakdown of the more stable cell proteins increased two- to threefold, whereas the hydrolysis of short-lived proteins, both normal ones and analog-containing polypeptides, did not change. The mechanisms initiating the enhancement of proteolysis during starvation for these ions were examined. Upon starvation for amino acids or amino acyl-transfer RNA (tRNA), protein breakdown increases in relA+ (but not relA) cells as a result of the rapid synthesis of guanosine-5'-diphosphate-3'-diphosphate (ppGpp). However, a lack of amino acyl-tRNA does not appear to be responsible for the increased protein breakdown in cells starved for inorganic ions, since protein breakdown increased in the absence of these ions in both relA+ and relA cultures, and since a large excess of amino acids did not affect this response. In bacteria in which energy production is restricted, ppGpp levels also rise, and protein breakdown increases. The ion-deprived cultures did show a 40 to 75% reduction in adenosine-5'-triphosphate levels,l similar to that seen upon glucose starvation. However, this decrease in ATP content does not appear to cause the increase in protein breakdown or lead to an accumulation of ppGpp. No consistent change in intracellular ppGpp levels was found in relA+ or relA cells starved for these ions. In addition, in relX mutants, removal of these ions led to accelerated protein degradation even though relX cells are unable to increase ppGpp levels or proteolysis when deprived of a carbon source. In the potassium-, phosphate-, and magnesium-deprived cultures, the addition of choramphenicol or tetracycline caused a reduction in protein breakdown toward basal levels. Such findings, however, do not indicate that protein synthesis is essential for the

  15. On the probability of exceeding allowable leak rates through degraded steam generator tubes

    SciTech Connect

    Cizelj, L.; Sorsek, I.; Riesch-Oppermann, H.

    1997-02-01

    This paper discusses some possible ways of predicting the behavior of the total leak rate through the damaged steam generator tubes. This failure mode is of special concern in cases where most through-wall defects may remain In operation. A particular example is the application of alternate (bobbin coil voltage) plugging criterion to Outside Diameter Stress Corrosion Cracking at the tube support plate intersections. It is the authors aim to discuss some possible modeling options that could be applied to solve the problem formulated as: Estimate the probability that the sum of all individual leak rates through degraded tubes exceeds the predefined acceptable value. The probabilistic approach is of course aiming at reliable and computationaly bearable estimate of the failure probability. A closed form solution is given for a special case of exponentially distributed individual leak rates. Also, some possibilities for the use of computationaly efficient First and Second Order Reliability Methods (FORM and SORM) are discussed. The first numerical example compares the results of approximate methods with closed form results. SORM in particular shows acceptable agreement. The second numerical example considers a realistic case of NPP in Krsko, Slovenia.

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

    PubMed Central

    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. PMID:27340465

  17. Electrochemical degradation of trichloroacetic acid in aqueous media: influence of the electrode material.

    PubMed

    Esclapez, M D; Díez-García, M I; Sàez, V; Bonete, P; González-García, José

    2013-01-01

    The electrochemical degradation of trichloroacetic acid (TCAA) in water has been analysed through voltammetric studies with a rotating disc electrode and controlled-potential bulk electrolyses. The influence of the mass-transport conditions and initial concentration of TCAA for titanium, stainless steel and carbon electrodes has been studied. It is shown that the electrochemical reduction of TCAA takes place prior to the massive hydrogen evolution in the potential window for all electrode materials studied. The current efficiency is high (> 18%) compared with those normally reported in the literature, and the fractional conversion is above 50% for all the electrodes studied. Only dichloroacetic acid (DCAA) and chloride anions were routinely detected as reduction products for any of the electrodes, and reasonable values of mass balance error were obtained. Of the three materials studied, the titanium cathode gave the best results. PMID:23530352

  18. Kinetic modeling of the photocatalytic degradation of clofibric acid in a slurry reactor.

    PubMed

    Manassero, Agustina; Satuf, María Lucila; Alfano, Orlando Mario

    2015-01-01

    A kinetic study of the photocatalytic degradation of the pharmaceutical clofibric acid is presented. Experiments were carried out under UV radiation employing titanium dioxide in water suspension. The main reaction intermediates were identified and quantified. Intrinsic expressions to represent the kinetics of clofibric acid and the main intermediates were derived. The modeling of the radiation field in the reactor was carried out by Monte Carlo simulation. Experimental runs were performed by varying the catalyst concentration and the incident radiation. Kinetic parameters were estimated from the experiments by applying a non-linear regression procedure. Good agreement was obtained between model predictions and experimental data, with an error of 5.9 % in the estimations of the primary pollutant concentration. PMID:24622987

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

    PubMed

    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

  20. Polycyclic aromatic hydrocarbon reaction rates with peroxy-acid treatment: prediction of reactivity using local ionization potential.

    PubMed

    Shoulder, J M; Alderman, N S; Breneman, C M; Nyman, M C

    2013-08-01

    Property-Encoded Surface Translator (PEST) descriptors were found to be correlated with the degradation rates of polycyclic aromatic hydrocarbons (PAHs) by the peroxy-acid process. Reaction rate constants (k) in hr(-1) for nine PAHs (acenaphthene, anthracene, benzo[a]pyrene, benzo[k]fluoranthene, fluoranthene, fluorene, naphthalene, phenanthrene, and pyrene) were determined by a peroxy-acid treatment method that utilized acetic acid, hydrogen peroxide, and a sulphuric acid catalyst to degrade the polyaromatic structures. Molecular properties of the selected nine PAHs were derived from structures optimized at B3LYP/6-31G(d) and HF/6-31G(d) levels of theory. Properties of adiabatic and vertical ionization potential (IP), highest occupied molecular orbitals (HOMO), HOMO/lowest unoccupied molecular orbital (LUMO) gap energies and HOMO/singly occupied molecular orbital (SOMO) gap energies were not correlated with rates of peroxy-acid reaction. PEST descriptors were calculated from B3LYP/6-31G(d) optimized structures and found to have significant levels of correlation with k. PIP Min described the minimum local IP on the surface of the molecule and was found to be related to k. PEST technology appears to be an accurate method in predicting reactivity and could prove to be a valuable asset in building treatment models and in remediation design for PAHs and other organic contaminants in the environment. PMID:23734862

  1. Photoelectrocatalytic degradation of benzoic acid using Au doped TiO2 thin films.

    PubMed

    Mohite, V S; Mahadik, M A; Kumbhar, S S; Hunge, Y M; Kim, J H; Moholkar, A V; Rajpure, K Y; Bhosale, C H

    2015-01-01

    Highly transparent pure and Au doped TiO2 thin films are successfully deposited by using simple chemical spray pyrolysis technique. The effect of Au doping onto the structural and physicochemical properties has been investigated. The PEC study shows that, both short circuit current (Isc) and open circuit voltage (Voc) are (Isc=1.81mA and Voc=890mV) relatively higher at 3at.% Au doping percentage. XRD study shows that the films are nanocrystalline in nature with tetragonal crystal structure. FESEM images show that the film surface covered with a smooth, uniform, compact and rice shaped nanoparticles. The Au doped thin films exhibit indirect band gap, decreases from 3.23 to 3.09eV with increase in Au doping. The chemical composition and valence states of pure and Au doped TiO2 films are studied by using X-ray photoelectron spectroscopy. The photocatalytic degradation effect is 49% higher in case 3at.% Au doped TiO2 than the pure TiO2 thin film photoelectrodes in the degradation of benzoic acid. It is revealed that Au doped TiO2 can be reused for five cycles of experiments without a requirement of post-treatment while the degradation efficiency was retained. PMID:25550120

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

    NASA Astrophysics Data System (ADS)

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

    2010-08-01

    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.

  3. Stability studies on trans-rosmarinic acid and GC-MS analysis of its degradation product.

    PubMed

    Razboršek, Maša Islamčević

    2011-07-15

    The stability of trans-rosmarinic acid (trans-RA, an important phenolic compound with anti-oxidant, anti-inflammatory, anti-bacterial, and anti-viral properties) exposed to different stress conditions (daylight, higher temperatures, different solvents, and humidity) was investigated. Gas chromatography-mass spectrometry (GC-MS) was used to analyse the degraded samples, and structural identification of degradation products was assigned based upon MS fragmentation pattern. The GC-MS method was validated in terms of linearity, precision as repeatability, accuracy, limit of detection (LOD), limit of quantitation (LOQ) and recovery. The stability experiments were performed on pure trans-RA and on trans-RA present in commercially available rosemary extract. The cis-isomer of RA was the only degradation product. The results showed that trans-RA was readily isomerized into its cis-form within a few hours when dissolved in ethanol, methanol or tetrahydrofuran, and exposed to darkness or daylight at different temperatures. Isomerization took place to a greater extent in protic than in aprotic solvents. Trans-RA in the solid state was found to be stable for up to three months under all tested conditions. The described GC-MS method was also applied to the determination of trans-RA in eight different species of Lamiaceae family. PMID:21515014

  4. Anaerobic Degradation of Uric Acid by Gut Bacteria of Termites †

    PubMed Central

    Potrikus, C. J.; Breznak, John A.

    1980-01-01

    A study was done of anaerobic degradation of uric acid (UA) by representative strains of uricolytic bacteria isolated from guts of Reticulitermes flavipes termites. Streptococcus strain UAD-1 degraded UA incompletely, secreting a fluorescent compound into the medium, unless formate (or a formicogenic compound) was present as a cosubstrate. Formate functioned as a reductant, and its oxidation to CO2 by formate dehydrogenase provided 2H+ + 2e− needed to drive uricolysis to completion. Uricolysis by Streptococcus UAD-1 thus corresponded to the following equation: 1UA + 1formate → 4CO2 + 1acetate + 4NH3. Urea did not appear to be an intermediate in CO2 and NH3 formation during uricolysis by strain UAD-1. Formate dehydrogenase and uricolytic activities of strain UAD-1 were inducible by growth of cells on UA. Bacteroides termitidis strain UAD-50 degraded UA as follows: 1UA → 3.5 CO2 + 0.75acetate + 4NH3. Exogenous formate was neither required for nor stimulatory to uricolysis by strain UAD-50. Studies of UA catabolism by Citrobacter strains were limited, because only small amounts of UA were metabolized by cells in liquid medium. Uricolytic activity of such bacteria in situ could be important to the carbon, nitrogen, and energy economy of R. flavipes. PMID:16345588

  5. The geochemical evolution of low-molecular-weight organic acids derived from the degradation of petroleum contaminants in groundwater

    USGS Publications Warehouse

    Cozzarelli, I.M.; Baedecker, M.J.; Eganhouse, R.P.; Goerlitz, D.F.

    1994-01-01

    The geochemical evolution of low-molecular-weight organic acids in groundwater downgradient from a crude-oil spill near Bemidji, Minnesota, was studied over a five year period (1986-1990). The organic acids are metabolic intermediates of the degradation of components of the crude oil and are structurally related to hydrocarbon precursors. The concentrations of organic acids, particularly aliphatic acids, increase as the microbial alteration of hydrocarbons progresses. The organic-acid pool changes in composition and concentration over time and in space as the degradation processes shift from Fe(III) reduction to methanogenesis. Over time, the aquifer system evolves into one in which the groundwater contains more oxidized products of hydrocarbon degradation and the reduced forms of iron, manganese, and nitrogen. Laboratory microcosm experiments with aquifer material support the hypothesis that organic acids observed in the groundwater originate from the microbial degradation of aromatic hydrocarbons under anoxic conditions. The geochemistry of two other shallow aquifers in coastal plain sediments, one contaminated with creosote waste and the other with gasoline, were compared to the Bemidji site. The geochemical evolution of the low-molecular-weight organic acid pool in these systems is controlled, in part, by the presence of electron acceptors available for microbially mediated electron-transfer reactions. The depletion of electron acceptors in aquifers leads to the accumulation of aliphatic organic acids in anoxic groundwater. ?? 1994.

  6. The geochemical evolution of low-molecular-weight organic acids derived from the degradation of petroleum contaminants in groundwater

    SciTech Connect

    Cozzarelli, I.M.; Baedecker, M.J.; Eganhouse, R.P. ); Goerlitz, D.F. )

    1994-01-01

    The geochemical evolution of low-molecular-weight organic acids in groundwater downgradient from a crude-oil spill near Bemidji, Minnesota, was studied over a five year period (1986-90). The organic acids are metabolic intermediates of the degradation of components of the crude oil and are structurally related to hydrocarbon precursors. The concentrations of organic acids, particularly aliphatic acids, increase as the microbial alteration of hydrocarbons progresses. The organic-acid pool changes in composition and concentration over time and in space as the degradation processes shift from Fe(III) reduction to methanogenesis. Over time, the aquifer system evolves into one in which the groundwater contains more oxidized products of hydrocarbon degradation and the reduced forms of iron, manganese, and nitrogen. Laboratory microcosm experiments with aquifer material support the hypothesis that organic acids observed in the groundwater originate from the microbial degradation of aromatic hydrocarbons under anoxic conditions. The geochemistry of two other shallow aquifers in coastal plain sediments, one contaminated with creosote waste and the other with gasoline, were compared to the Bemidji site. The geochemical evolution of the low-molecular-weight organic acid pool in these systems is controlled, in part, by the presence of electron acceptors available for microbially mediated electron-transfer reactions. The depletion of electron acceptors in aquifers leads to the accumulation of aliphatic organic acids in anoxic groundwater.

  7. Kinetics of the competitive degradation of deoxyribose and other molecules by hydroxyl radicals produced by the Fenton reaction in the presence of ascorbic acid.

    PubMed

    Zhao, M J; Jung, L

    1995-09-01

    The competition method in which the Fenton reaction is employed as an .OH radical generator and deoxyribose as a detecting molecule, has been used to determine the rate constants for reactions of the .OH radical with its scavengers. Nonlinear competition plots were obtained for those scavengers which reacted with the Fenton reagents (Fe2+ or H2O2). Ascorbic acid is believed to overcome this problem. We have investigated the kinetics of deoxyribose degradation by .OH radicals generated by the Fenton reaction in the presence of ascorbic acid, and observed that the inclusion of ascorbic acid in the Fenton system greatly increased the rate of .OH radical generation. As a result, the interaction between some scavengers and the Fenton reagents became negligeable and linear competition plots of A degree/A vs scavenger concentrations were obtained. The effects of experimental conditions such as, the concentrations of ascorbic acid, deoxyribose, H2O2 and Fe(2+)-EDTA, the EDTA/Fe2+ ratio as well as the incubation time, on the deoxyribose degradation and the determination of the rate constant for mercaptoethanol chosen as a reference compound were studied. The small standard error, (6.76 +/- 0.21) x 10(9) M-1s-1, observed for the rate constant values for mercaptoethanol determined under 13 different experimental conditions, indicates the latter did not influence the rate constant determination. This is in fact assured by introducing a term, kx, into the kinetic equation. This term represents the rate of .OH reactions with other reagents such as ascorbic acid, Fe(2+)-EDTA, H2O2 etc. The agreement of the rate constants obtained in this work with that determined by pulse radiolysis techniques for cysteine, thiourea and many other scavengers, suggests that this simple competition method is applicable to a wide range of compounds, including those which react with the Fenton reagents and those whose solubility in water is low. PMID:7581818

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

    NASA Astrophysics Data System (ADS)

    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

  9. Analysis of Hydroxycinnamic Acid Degradation in Agrobacterium fabrum Reveals a Coenzyme A-Dependent, Beta-Oxidative Deacetylation Pathway

    PubMed Central

    Campillo, Tony; Renoud, Sébastien; Kerzaon, Isabelle; Vial, Ludovic; Baude, Jessica; Gaillard, Vincent; Bellvert, Floriant; Chamignon, Cécile; Comte, Gilles; Lavire, Céline; Hommais, Florence

    2014-01-01

    The soil- and rhizosphere-inhabiting bacterium Agrobacterium fabrum (genomospecies G8 of the Agrobacterium tumefaciens species complex) is known to have species-specific genes involved in ferulic acid degradation. Here, we characterized, by genetic and analytical means, intermediates of degradation as feruloyl coenzyme A (feruloyl-CoA), 4-hydroxy-3-methoxyphenyl-β-hydroxypropionyl–CoA, 4-hydroxy-3-methoxyphenyl-β-ketopropionyl–CoA, vanillic acid, and protocatechuic acid. The genes atu1416, atu1417, and atu1420 have been experimentally shown to be necessary for the degradation of ferulic acid. Moreover, the genes atu1415 and atu1421 have been experimentally demonstrated to be essential for this degradation and are proposed to encode a phenylhydroxypropionyl-CoA dehydrogenase and a 4-hydroxy-3-methoxyphenyl-β-ketopropionic acid (HMPKP)–CoA β-keto-thiolase, respectively. We thus demonstrated that the A. fabrum hydroxycinnamic degradation pathway is an original coenzyme A-dependent β-oxidative deacetylation that could also transform p-coumaric and caffeic acids. Finally, we showed that this pathway enables the metabolism of toxic compounds from plants and their use for growth, likely providing the species an ecological advantage in hydroxycinnamic-rich environments, such as plant roots or decaying plant materials. PMID:24657856

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

    PubMed

    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

  11. Acid phosphatase activity and intracellular collagen degradation by fibroblasts in vitro.

    PubMed

    Yajima, T

    1986-01-01

    Human gingival fibroblasts were cultured with collagen fibrils. The precise process of collagen phagocytosis and the relationship between acid phosphatase activity and intracellular degradation of collagen were investigated by cytochemical methods at the ultrastructural level. The collagen fibrils were first engulfed at one end by cellular processes, or the cell membrane wrapped itself around the middle of the fibrils. Collagen phagocytosis induced acid phosphatase activity in the fibroblast Golgi-endoplasmic reticulum-lysosome system. By application of the tracer lanthanum, deposits were observed in the intercellular spaces and along the fibrils being phagocytosed. At this stage, primary lysosomes were seen in close proximity to the collagen being engulfed, but no signs of fusion were observed. When the fibrils had been interiorized in whole or in part, they ultimately became enclosed within phagosomes, and no tracer was observed along the interiorized portion of the fibrils. Primary lysosomes then fused with these collagen-containing phagosomes to form phagolysosomes. Collagen degradation occurred within these bodies even though the end of a fibril might have protruded outside of the cell. These results suggest that selective and controlled phagocytosis of collagen and intracellular digestion of it may play a central role in the physiological remodeling and metabolic breakdown of the collagen of connective tissues. PMID:3742560

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

    PubMed

    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

  13. Experimental study of humic acid degradation and theoretical modelling of catalytic ozonation.

    PubMed

    Turkay, Ozge; Inan, Hatice; Dimoglo, Anatoli

    2015-01-01

    The efficiency of TiO2 as a catalyst in the ozonation of humic acid (HA) was evaluated in a comprehensive manner. Ozonation, catalytic ozonation and adsorption experiments were conducted using both synthetic HA solution and natural water. HA degradation was evaluated in terms of DOC, VIS400 and UV254. It was shown that the addition of catalyst positively affects the mechanism of ozonation. An increase in HA degradation was observed for all these parameters. The impact of catalyst dose and initial pH value of HA on the efficacy of catalytic ozonation was investigated. The highest removal efficiencies were achieved with the dose of 1 g l(-1) of TiO2 (Degussa P-25) and in the acidic pH region. The catalytic ozonation process was efficient also on natural water component although not at the same level as it was on synthetic water. The adsorptive feature of P-25 was considered to have a clear evidence of the catalytic ozonation mechanism. The mechanism of catalysis on the surface of metal oxides was elucidated with the help of quantum-chemical calculations. In the framework of Density Function Theory (DFT), the O3 decomposition was calculated in the catalytic and non-catalytic processes. Donor-acceptor properties of the frontier (highest occupied and lowest unoccupied molecular orbitals, HOMO/LUMO) orbitals are discussed. Electron density distribution and reaction mechanism of superoxide particles formation, which participate in the process of HA ozonation are analyzed. PMID:25056748

  14. Enhanced propionic acid degradation (EPAD) system: proof of principle and feasibility.

    PubMed

    Ma, Jingxing; Carballa, Marta; Van De Caveye, Pieter; Verstraete, Willy

    2009-07-01

    Full-scale anaerobic single-phase digesters can be confronted with process instabilities, which often result in the accumulation of propionic acid (HPr). As a solution, an enhanced propionic acid degradation (EPAD) system has been conceptually designed and experimentally tested at lab-scale. The system consisted of two components: a liquid/solid separator containing a microfiltration membrane and an up-flow anaerobic sludge bed (UASB) reactor specialized in HPr degradation. Two lab-scale continuous stirred tank reactors (CSTR) were used, i.e. the CSTR(control) and the CSTR(treatment). Firstly, the CSTRs were stressed by organic overloading to obtain high HPr levels. During the recovery period, besides stop feeding, no actions were taken to decrease the residual HPr concentration in the CSTR(control), while the CSTR(treatment) was connected to EPAD system in order to accelerate its recovery. By the end of the experiment, the CSTR(treatment) completely recovered from HPr accumulation, while no significant decrease of the HPr level in the CSTR(control) was observed. Based on the experimental results, the up-scaling of EPAD system was evaluated and it would only account for about 2% of the volume of the full-scale digester, thus suggesting that the implementation of a mobile EPAD system in full-scale practice should be feasible. PMID:19515396

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

    PubMed

    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

  16. Degradation of carbohydrates during dilute sulfuric acid pretreatment can interfere with lignin measurements in solid residues.

    PubMed

    Katahira, Rui; Sluiter, Justin B; Schell, Daniel J; Davis, Mark F

    2013-04-01

    The lignin content measured after dilute sulfuric acid pretreatment of corn stover indicates more lignin than could be accounted for on the basis of the untreated corn stover lignin content. This phenomenon was investigated using a combination of (13)C cross-polarization/magic-angle spinning (CP/MAS) solid-state nuclear magnetic resonance (NMR) spectroscopy and lignin removal using acid chlorite bleaching. Only minimal contamination with carbohydrates and proteins was observed in the pretreated corn stover. Incorporating degradation products from sugars was also investigated using (13)C-labeled sugars. The results indicate that sugar degradation products are present in the pretreatment residue and may be intimately associated with the lignin. Studies comparing whole corn stover (CS) to extractives-free corn stover [CS(Ext)] clearly demonstrated that extractives are a key contributor to the high-lignin mass balance closure (MBC). Sugars and other low molecular weight compounds present in plant extractives polymerize and form solids during pretreatment, resulting in apparent Klason lignin measurements that are biased high. PMID:23428141

  17. In vitro stress effect on degradation and drug release behaviors of basic fibroblast growth factor – poly(lactic-co-glycolic-acid) microsphere

    PubMed Central

    Xiong, Yan; Yu, Zeping; Lang, Yun; Hu, Juanyu; Li, Hong; Yan, Yonggang; Tu, Chongqi; Yang, Tianfu; Song, Yueming; Duan, Hong; Pei, Fuxing

    2016-01-01

    Objective To study the degradation and basic fibroblast growth factor (bFGF) release activity of bFGF – poly(lactic-co-glycolic-acid) microsphere (bFGF-PLGA MS) under stress in vitro, including the static pressure and shearing force-simulating mechanical environment of the joint cavity. Method First, bFGF-PLGA MSs were created. Meanwhile, two self-made experimental instruments (static pressure and shearing force loading instruments) were initially explored to provide stress-simulating mechanical environment of the joint cavity. Then, bFGF-PLGA MSs were loaded into the two instruments respectively, to study microsphere degradation and drug release experiments. In the static pressure loading experiment, normal atmospheric pressure loading (approximately 0.1 MPa), 0.35 MPa, and 4.0 MPa pressure loading and shaking flask oscillation groups were designed to study bFGF-PLGA MS degradation and bFGF release. In the shearing force loading experiment, a pulsating pump was used to give the experimental group an output of 1,000 mL/min and the control group an output of 10 mL/min to carry out bFGF-PLGA MS degradation and drug release experiments. Changes of bFGF-PLGA MSs, including microsphere morphology, quality, weight-average molecular weight of polymer, and microsphere degradation and bFGF release, were analyzed respectively. Results In the static pressure loading experiment, bFGF-PLGA MSs at different pressure were stable initially. The trend of molecular weight change, quality loss, and bFGF release was consistent. Meanwhile, microsphere degradation and bFGF release rates in the 4.0 MPa pressure loading group were faster than those in the normal and 0.35 MPa pressure loading groups. It was the fastest in the shaking flask group, showing a statistically significant difference (P<0.0001). In the shearing force loading experiment, there were no distinctive differences in the rates of microsphere degradation and bFGF release between experimental and control group. Meanwhile

  18. Comparative electrochemical degradation of salicylic and aminosalicylic acids: Influence of functional groups on decay kinetics and mineralization.

    PubMed

    Florenza, Xavier; Garcia-Segura, Sergi; Centellas, Francesc; Brillas, Enric

    2016-07-01

    Solutions of 100 mL with 1.20 mM of salicylic acid (SA), 4-aminosalicylic acid (4-ASA) or 5-aminosalicylic acid (5-ASA) have been comparatively degraded by anodic oxidation with electrogenerated H2O2 (AO-H2O2), electro-Fenton (EF) and photoelectro-Fenton (PEF). Trials were carried out with a stirred tank reactor with a BDD anode and an air-diffusion cathode for continuous H2O2 production. A marked influence of the functional groups of the drugs was observed in their decay kinetics, increasing in the order SA < 5-ASA < 4-ASA in AO-H2O2 and 5-ASA < SA < 4-ASA in EF and PEF, due to the different attack of OH generated at the BDD surface and in the bulk from Fenton's reaction, respectively. This effect was clearly observed when varying the current density between 16.7 and 100 mA cm(-2). The relative mineralization power of the processes always followed the sequence: AO-H2O2 < EF < PEF. The three drugs underwent analogous mineralization abatement up to 88% by AO-H2O2 at 100 mA cm(-2). The mineralization rate in EF and PEF grew in the order: 4-ASA < 5-ASA < SA. The most powerful process was PEF, attaining >98% mineralization for all the drugs at 100 mA cm(-2). Oxalic and oxamic acids were detected as final short-linear aliphatic carboxylic acids by ion-exclusion HPLC, allowing the fast photolysis of their Fe(III) complexes by UVA light to justify the high power of PEF. PMID:27045634

  19. Controlling the degradation kinetics of porous iron by poly(lactic-co-glycolic acid) infiltration for use as temporary medical implants

    PubMed Central

    Yusop, Abdul Hakim Md; Daud, Nurizzati Mohd; Nur, Hadi; Kadir, Mohammed Rafiq Abdul; Hermawan, Hendra

    2015-01-01

    Iron and its alloy have been proposed as biodegradable metals for temporary medical implants. However, the formation of iron oxide and iron phosphate on their surface slows down their degradation kinetics in both in vitro and in vivo scenarios. This work presents new approach to tailor degradation behavior of iron by incorporating biodegradable polymers into the metal. Porous pure iron (PPI) was vacuum infiltrated by poly(lactic-co-glycolic acid) (PLGA) to form fully dense PLGA-infiltrated porous iron (PIPI) and dip coated into the PLGA to form partially dense PLGA-coated porous iron (PCPI). Results showed that compressive strength and toughness of the PIPI and PCPI were higher compared to PPI. A strong interfacial interaction was developed between the PLGA layer and the iron surface. Degradation rate of PIPI and PCPI was higher than that of PPI due to the effect of PLGA hydrolysis. The fast degradation of PIPI did not affect the viability of human fibroblast cells. Finally, this work discusses a degradation mechanism for PIPI and the effect of PLGA incorporation in accelerating the degradation of iron. PMID:26057073

  20. Controlling the degradation kinetics of porous iron by poly(lactic-co-glycolic acid) infiltration for use as temporary medical implants

    NASA Astrophysics Data System (ADS)

    Yusop, Abdul Hakim Md; Daud, Nurizzati Mohd; Nur, Hadi; Kadir, Mohammed Rafiq Abdul; Hermawan, Hendra

    2015-06-01

    Iron and its alloy have been proposed as biodegradable metals for temporary medical implants. However, the formation of iron oxide and iron phosphate on their surface slows down their degradation kinetics in both in vitro and in vivo scenarios. This work presents new approach to tailor degradation behavior of iron by incorporating biodegradable polymers into the metal. Porous pure iron (PPI) was vacuum infiltrated by poly(lactic-co-glycolic acid) (PLGA) to form fully dense PLGA-infiltrated porous iron (PIPI) and dip coated into the PLGA to form partially dense PLGA-coated porous iron (PCPI). Results showed that compressive strength and toughness of the PIPI and PCPI were higher compared to PPI. A strong interfacial interaction was developed between the PLGA layer and the iron surface. Degradation rate of PIPI and PCPI was higher than that of PPI due to the effect of PLGA hydrolysis. The fast degradation of PIPI did not affect the viability of human fibroblast cells. Finally, this work discusses a degradation mechanism for PIPI and the effect of PLGA incorporation in accelerating the degradation of iron.

  1. Controlling the degradation kinetics of porous iron by poly(lactic-co-glycolic acid) infiltration for use as temporary medical implants.

    PubMed

    Yusop, Abdul Hakim Md; Daud, Nurizzati Mohd; Nur, Hadi; Kadir, Mohammed Rafiq Abdul; Hermawan, Hendra

    2015-01-01

    Iron and its alloy have been proposed as biodegradable metals for temporary medical implants. However, the formation of iron oxide and iron phosphate on their surface slows down their degradation kinetics in both in vitro and in vivo scenarios. This work presents new approach to tailor degradation behavior of iron by incorporating biodegradable polymers into the metal. Porous pure iron (PPI) was vacuum infiltrated by poly(lactic-co-glycolic acid) (PLGA) to form fully dense PLGA-infiltrated porous iron (PIPI) and dip coated into the PLGA to form partially dense PLGA-coated porous iron (PCPI). Results showed that compressive strength and toughness of the PIPI and PCPI were higher compared to PPI. A strong interfacial interaction was developed between the PLGA layer and the iron surface. Degradation rate of PIPI and PCPI was higher than that of PPI due to the effect of PLGA hydrolysis. The fast degradation of PIPI did not affect the viability of human fibroblast cells. Finally, this work discusses a degradation mechanism for PIPI and the effect of PLGA incorporation in accelerating the degradation of iron. PMID:26057073

  2. FATE OF FENTHION IN SALT-MARSH ENVIRONMENTS: 1. FACTORS AFFECTING BIOTIC AND ABIOTIC DEGRADATION RATES IN WATER AND SEDIMENT

    EPA Science Inventory

    Fenthion (Baytex), an organophosphate insecticide, is frequently applied to salt-marsh environments to control mosquitoes. hake-flask tests were used to study rates of abiotic and biotic degradation of fenthion and the environmental parameters that affect these rates. Water or wa...

  3. Intrinsic degradation of volatile fatty acids in laboratory-compacted clayey soil

    NASA Astrophysics Data System (ADS)

    Hrapovic, L.; Rowe, R. K.

    2002-10-01

    Volatile fatty acids (VFAs) represent the major organic constituent of landfill leachate and provide the greatest potential for leachate induced organic contamination of groundwater (e.g. as represented by an increase in the concentration of dissolved organic carbon and chemical oxygen demand). Long-term diffusion tests were performed for laboratory-compacted clayey soil plugs exposed to continuous supply of synthetic leachate containing VFAs. Significant microbial activity developed upon exposure of the soil's indigenous microorganisms to these degradable contaminants. The growth of heterotrophic aerobic bacteria (HAB, which include facultative anaerobes), sulfate reducing bacteria (SRB) and methanogenic bacteria carrying out fermentation and mineralization of the VFAs became evident after 30-50 days of testing. The maximum microbial counts of (2-8)×10 8 and (0.1-1)×10 8 cfu/g for HAB and SRB were localized in the soil layer at the interface with the source of organic and inorganic nutrients. Regardless of this rapid growth in microbial population, the VFA consumption was small and measurable only after a lag of 140-180 days. It is considered that this lag of otherwise readily degradable organic compounds (such as VFAs) persisted due to a combination of the effects of a high initial concentration of these acids (2.4 g/l as dissolved organic carbon, DOC) applied to carbon starved soil microorganisms and the small pore size of the compacted clay. Once the significant amounts of gas were generated from fermentation, conditions developed for improved mass transport and exchange of the nutrients and bacteria and the outcome of the intrinsic degradation was more apparent. The breakdown of VFAs that followed after the lag was localized near the top of the soil and was characterized by a short half-life of 0.75-5 days for DOC (total VFAs as dissolved organic carbon).

  4. Pristine environments harbor a new group of oligotrophic 2,4-dichlorophenoxyacetic acid-degrading bacteria.

    PubMed Central

    Kamagata, Y; Fulthorpe, R R; Tamura, K; Takami, H; Forney, L J; Tiedje, J M

    1997-01-01

    2,4-Dichlorophenoxyacetic acid (2,4-D)-degrading bacteria were isolated from pristine environments which had no history of 2,4-D exposure. By using 2,4-D dye indicator medium or 14C-labeled 2,4-D medium, six strains were isolated from eight enrichment cultures capable of degrading 2,4-D. Phylogenetic analyses based on 16S ribosomal DNA (rDNA) sequencing and physiological properties revealed that one isolate from Hawaiian volcanic soil could be classified in the genus Variovorax (a member of the beta subdivision of the class Proteobacteria) and that the other five isolates from Hawaiian volcanic soils, Saskatchewan forest soil, and Chilean forest soil have 16S rDNAs with high degrees of similarity to those of the Bradyrhizobium group (a member of the alpha subdivision of the class Proteobacteria). All the isolates grow slowly on either nutrient media (0.1 x Bacto Peptone-tryptone-yeast extract-glucose [PTYG] or 0.1 x Luria broth [LB] medium) or 2,4-D medium, with mean generation times of 16 to 30 h, which are significantly slower than previously known 2,4-D degraders. Nutrient-rich media such as full-strength PTYG and LB medium did not allow their growth. PCR amplification using internal consensus sequences of tfdA (a gene encoding an enzyme for the first step of 2,4-D mineralization, found in pJP4 of Alcaligenes eutrophus JMP134 and some other 2,4-D-degrading bacteria) as primers and Southern hybridization with pJP4-tfdA as a probe revealed that the isolate belonging to the genus Variovorax carried the tfdA gene. This gene was transmissible to A. eutrophus JMP228 carrying a plasmid with a mutant tfdA gene. The other five isolates did not appear to carry tfdA, and 2,4-D-specific alpha-ketoglutarate-dependent dioxygenase activity could not be detected in cell lysates. These results indicate that 2,4-D-degrading bacteria in pristine environments are slow-growing bacteria and that most of their phylogenies and catabolic genes differ from those of 2,4-D degraders

  5. Energetics and kinetics of anaerobic aromatic and fatty acid degradation. Progress report, November 1993--November 1994

    SciTech Connect

    McInerney, M.J.

    1994-12-06

    Factors influencing the rate and extent of benzoate degradation by the anaerobic syntrophic consortia were studied. Nonlinear regression analysis showed that the cause of the benzoate threshold was not a diminished benzoate degradation capacity. Analysis of cocultures with hydrogen users that differed in their hydrogen utilization capacities showed that the threshold did not depend on the kinetic properties of the syntrophic partner. These data support a thermodynamic explanation for the threshold, and exclude the possibility that a change in the affinity of the enzyme system due to acetate inhibition caused the threshold. Modeling studies showed that the threshold value could be predicted from the concentrations of the end products, assuming a critical Gibb`s free energy value. This work shows that interspecies acetate transfer is important in controlling the extent of metabolism by syntrophic organisms.

  6. Do stable nitroxide radicals catalyze or inhibit the degradation of hyaluronic acid?

    PubMed

    Lurie, Ziva; Offer, Tal; Russo, Angelo; Samuni, Amram; Nitzan, Dorrit

    2003-07-15

    Reactive oxygen-derived species and particularly OH radicals can degrade hyaluronic acid (HA), resulting in a loss of viscosity and a subsequent decrease in its effectiveness as a joint-lubricating agent. The production of OH in the vicinity of HA can be catalyzed by bound redox-active metals, which participate in the Haber-Weiss reaction. Damage to HA can also occur as a result of hypochlorite formed by myeloperoxidase (MPO). The protective reagents commonly used to inhibit oxidative stress-induced degradation of HA include antioxidative enzymes, such as SOD and catalase, chelators that coordinate metal ions rendering them redox-inactive, and scavengers of radicals, such as OH, as well as nonradical reactive species. In recent years, stable cyclic nitroxides have also been widely used as effective antioxidants. In many cases, nitroxide antioxidants operate catalytically and mediate their protective effect through an exchange between their oxidized and reduced forms. It was anticipated, therefore, that nitroxides would protect HA from oxidative degradation as well. On the other hand, nitroxides serve as catalysts in many oxidation reactions of alcohols, sugars and polysaccharides, including hyalouronan. Such opposite effects of nitroxides on oxidative degradation are particularly intriguing and the aim of the present study was to examine their effect on HA when subjected to diverse forms of oxidative stress. The results indicate that nitroxides protect HA from OH radicals generated enzymatically or radiolytically. The protective effect is attributable neither to the scavenging of OH nor to the oxidation of reduced metal, but to the reaction of nitroxides with secondary carbohydrate radicals-most likely peroxyl radicals. PMID:12853073

  7. Use of an acidic Fe/O{sub 2} cell for wastewater treatment: Degradation of aniline

    SciTech Connect

    Brillas, E.; Sauleda, R.; Casado, J.

    1999-12-01

    Solutions containing 0.50 mol dm{sup {minus}3} Na{sub 2}SO{sub 4} and aniline concentrations between 129 and 1,000 ppm have been decontaminated using an acidic Fe/O{sub 2} cell with an Fe anode and a carbon-poly(tetrafluoroethylene) O{sub 2}-fed cathode. This system produces spontaneously strong oxidizing radicals, such as OH{sup {sm{underscore}bullet}} and HO{sub 2}{sup {sm{underscore}bullet}}, which react with pollutants. Decontamination is more efficient for solutions with pH > 3 where intermediates coagulate with the Fe(OH){sub 3} precipitate formed. A 95% degradation is reached after 1 h of treatment of 129 ppm of aniline at initial pH 4 and at 35 C. For higher substrate levels, pollutants are quickly destroyed if the pH is regulated between 4 and 5. After 2 h, solutions up to 500 ppm of aniline are almost completely degraded, whereas 81% of the degradation is reached for 1,000 ppm of substrate. Benzoquinone and nitrobenzene are detected as intermediates. An insignificant accumulation of these products is found in the treatment of 1,000 ppm of substrate, suggesting the formation of polymers that coagulate with the Fe(OH){sub 3} precipitate. Low concentrations of ammonium and nitrate ions have been determined in treated solutions. The major part of the initial carbon and nitrogen is retained in the precipitate, indicating that coagulation of intermediates predominates over their mineralization. A reaction pathway for the degradation of aniline involving all intermediates detected is proposed.

  8. Ligand-functionalized degradable polyplexes formed by cationic poly(aspartic acid)-grafted chitosan-cyclodextrin conjugates

    NASA Astrophysics Data System (ADS)

    Song, Hai-Qing; Li, Rui-Quan; Duan, Shun; Yu, Bingran; Zhao, Hong; Chen, Da-Fu; Xu, Fu-Jian

    2015-03-01

    Polypeptide-based degradable polyplexes attracted considerable attention in drug delivery systems. Polysaccharides including cyclodextrin (CD), dextran, and chitosan (CS) were readily grafted with cationic poly(aspartic acid)s (PAsps). To further enhance the transfection performances of PAsp-based polyplexes, herein, different types of ligand (folic acid, FA)-functionalized degradable polyplexes were proposed based on the PAsp-grafted chitosan-cyclodextrin conjugate (CCPE), where multiple β-CDs were tied on a CS chain. The FA-functionalized CCPE (i.e., CCPE-FA) was obtained via a host-guest interaction between the CD units of CCPE and the adamantane (Ad) species of Ad-modified FA (Ad-FA). The resulting CCPE/pDNA, CCPE-FA/pDNA, and ternary CCPE-FA/CCPE/pDNA (prepared by layer-by-layer assembly) polyplexes were investigated in detail using different cell lines. The CCPE-based polyplexes displayed much higher transfection efficiencies than the CS-based polyplexes reported earlier by us. The ternary polyplexes of CCPE-FA/CCPE/pDNA produced excellent gene transfection abilities in the folate receptor (FR)-positive tumor cells. This work would provide a promising means to produce highly efficient polyplexes for future gene therapy applications.Polypeptide-based degradable polyplexes attracted considerable attention in drug delivery systems. Polysaccharides including cyclodextrin (CD), dextran, and chitosan (CS) were readily grafted with cationic poly(aspartic acid)s (PAsps). To further enhance the transfection performances of PAsp-based polyplexes, herein, different types of ligand (folic acid, FA)-functionalized degradable polyplexes were proposed based on the PAsp-grafted chitosan-cyclodextrin conjugate (CCPE), where multiple β-CDs were tied on a CS chain. The FA-functionalized CCPE (i.e., CCPE-FA) was obtained via a host-guest interaction between the CD units of CCPE and the adamantane (Ad) species of Ad-modified FA (Ad-FA). The resulting CCPE/pDNA, CCPE

  9. Characterization of Wall Teichoic Acid Degradation by the Bacteriophage ϕ29 Appendage Protein GP12 Using Synthetic Substrate Analogs.

    PubMed

    Myers, Cullen L; Ireland, Ronald G; Garrett, Teresa A; Brown, Eric D

    2015-07-31

    The genetics and enzymology of the biosynthesis of wall teichoic acid have been the extensively studied, however, comparatively little is known regarding the enzymatic degradation of this biological polymer. The GP12 protein from the Bacillus subtilis bacteriophage ϕ29 has been implicated as a wall teichoic acid hydrolase. We have studied the wall teichoic acid hydrolase activity of pure, recombinant GP12 using chemically defined wall teichoic acid analogs. The GP12 protein had potent wall teichoic acid hydrolytic activity in vitro and demonstrated ∼13-fold kinetic preference for glycosylated poly(glycerol phosphate) teichoic acid compared with non-glycosylated. Product distribution patterns suggested that the degradation of glycosylated polymers proceeded from the hydroxyl terminus of the polymer, whereas hydrolysis occurred at random sites in the non-glycosylated polymer. In addition, we present evidence that the GP12 protein possesses both phosphodiesterase and phosphomonoesterase activities. PMID:26085106

  10. Synergy between surface adsorption and photocatalysis during degradation of humic acid on TiO2/activated carbon composites.

    PubMed

    Xue, Gang; Liu, Huanhuan; Chen, Quanyuan; Hills, Colin; Tyrer, Mark; Innocent, Francis

    2011-02-15

    A photocatalyst comprising nano-sized TiO(2) particles on granular activated carbon (GAC) was prepared by a sol-dipping-gel process. The TiO(2)/GAC composite was characterized by scanning electron microscopy (SEM), X-ray diffractiometry (XRD) and nitrogen sorptometry, and its photocatalytic activity was studied through the degradation of humic acid (HA) in a quartz glass reactor. The factors influencing photocatalysis were investigated and the GAC was found to be an ideal substrate for nano-sized TiO(2) immobilization. A 99.5% removal efficiency for HA from solution was achieved at an initial concentration of 15 mg/L in a period of 3h. It was found that degradation of HA on the TiO(2)/GAC composite was facilitated by the synergistic relationship between surface adsorption characteristics and photocatalytic potential. The fitting of experimental results with the Langmuir-Hinshelwood (L-H) model showed that the reaction rate constant and the adsorption constant values were 0.1124 mg/(L min) and 0.3402 L/mg. The latter is 1.7 times of the calculated value by fitting the adsorption equilibrium data into the Langmuir equation. PMID:21163573

  11. Green stabilization of microscale iron particles using guar gum: bulk rheology, sedimentation rate and enzymatic degradation.

    PubMed

    Gastone, Francesca; Tosco, Tiziana; Sethi, Rajandrea

    2014-05-01

    Guar gum can be used to effectively improve stability and mobility of microscale zerovalent iron particles (MZVI) used in groundwater remediation. Guar gum is a food-grade, environment friendly natural polysaccharide, which is often used as thickening agent in a broad range of food, pharmaceutical and industrial applications. Guar gum solutions are non-Newtonian, shear thinning fluids, characterized by high viscosity in static conditions and low viscosity in dynamic conditions. In particular, the high zero shear viscosity guarantees the MZVI dispersion stability, reducing the sedimentation rate of the particles thus enabling its storage and field operations. In this work, a comprehensive rheological characterization of guar gum-based slurries of MZVI particles is provided. First, we derived a model to link the bulk shear viscosity to the concentration of guar gum and then we applied it for the derivation of a modified Stokes law for the prediction of the sedimentation rate of the iron particles. The influence of the preparation procedure (cold or hot dissolution and high shear processing) on the viscosity and on the stability of the suspensions was then assessed. Finally, the dosage and concentration of enzymes - an environment friendly breaker--were studied for enhancing and controlling the degradation kinetics of the suspensions. The derived empirical relationships can be used for the implementation of an iron slurry flow and transport model and for the design of full scale injection interventions. PMID:24594029

  12. Potential Landscape and Flux of p53-Mdm2 Oscillator Mediated by Mdm2 Degradation Rate

    NASA Astrophysics Data System (ADS)

    Bi, Yuanhong; Yang, Zhuoqin

    The dynamics of the tumor suppressor p53 can play a crucial role in deciding cell fate after DNA damage. In this paper, we explore the dynamics and stability of p53 mediated by Mdm2 degradation rate in p53-Mdm2 oscillator through bifurcation, the potential landscape and flux. Based on the investigation of the bifurcation, we find that p53 can exhibit rich dynamics including monostability, bistability of two stable steady states and oscillation behaviors as well as bistability between a stable steady state and an oscillatory state. The stability of these states are further validated by the potential landscape. In addition, oscillatory behaviors of p53 are explored by means of the negative gradient of the potential landscape and the probability flux. It is shown that the negative gradient of the potential landscape can attract the system towards the oscillatory path and the flux can drive oscillation along the path. Moreover, the quicker the flux runs, the smaller the period is. Besides, stability and sensitivity of the system are explored by the barrier height and the entropy production rate in a single cell level, and we further compare the potential landscapes at single and population cell levels. Our results may be useful for understanding the regulation of p53 signaling pathways in response to DNA damage.

  13. Mevalonic acid-dependent degradation of 3-hydroxy-3-methylglutaryl-coenzyme A reductase in vivo and in vitro.

    PubMed

    Correll, C C; Edwards, P A

    1994-01-01

    The microsomal enzyme 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase is subject to rapid degradation when cells are incubated with sterols or mevalonic acid (MVA). It has been shown that this rapid degradation is dependent upon both a sterol and another MVA-derived metabolite (Nakanishi, M., Goldstein, J. L., and Brown, M. S. (1988) J. Biol. Chem. 258, 8929-8937). In the current study, inhibitors of the isoprene biosynthetic pathway were used to define further this mevalonic acid derivative involved in the accelerated degradation of HMG-CoA reductase. The accelerated degradation of HMG-CoA reductase in met-18b-2 cells, which is induced by the addition of MVA, was inhibited by the presence of the squalene synthase inhibitor, zaragozic acid/squalestatin, or the squalene epoxidase inhibitor, NB-598. Accelerated degradation of HMG-CoA reductase was observed when NB-598-treated cells were incubated with both MVA and sterols. In contrast, the addition of MVA and sterols to zaragozic acid/squalestatin-treated cells did not result in rapid enzyme degradation. This MVA- and sterol-dependent degradation of HMG-CoA reductase persisted in cells permeabilized with reduced streptolysin O. Finally, the selective degradation of HMG-CoA reductase was also observed in rat hepatic microsomes incubated in vitro in the absence of ATP and cytosol. We conclude that the MVA-derived component that is required for the accelerated degradation of HMG-CoA reductase is derived from farnesyl disphosphate and/or squalene in the isoprenoid biosynthetic pathway. We propose that this component has a permissive effect and does not, by itself, induce the degradation of HMG-CoA reductase. We also conclude that the degradation of HMG-CoA occurs in the endoplasmic reticulum, and, once the degradation of HMG-CoA reductase has been initiated by MVA and sterols, all necessary components for the continued degradation of HMG-CoA reductase reside in the endoplasmic reticulum. PMID:8276863

  14. Effect of Dissemination of 2,4-Dichlorophenoxyacetic Acid (2,4-D) Degradation Plasmids on 2,4-D Degradation and on Bacterial Community Structure in Two Different Soil Horizons

    PubMed Central

    Dejonghe, Winnie; Goris, Johan; El Fantroussi, Saïd; Höfte, Monica; De Vos, Paul; Verstraete, Willy; Top, Eva M.

    2000-01-01

    Transfer of the 2,4-dichlorophenoxyacetic acid (2,4-D) degradation plasmids pEMT1 and pJP4 from an introduced donor strain, Pseudomonas putida UWC3, to the indigenous bacteria of two different horizons (A horizon, depth of 0 to 30 cm; B horizon, depth of 30 to 60 cm) of a 2,4-D-contaminated soil was investigated as a means of bioaugmentation. When the soil was amended with nutrients, plasmid transfer and enhanced degradation of 2,4-D were observed. These findings were most striking in the B horizon, where the indigenous bacteria were unable to degrade any of the 2,4-D (100 mg/kg of soil) during at least 22 days but where inoculation with either of the two plasmid donors resulted in complete 2,4-D degradation within 14 days. In contrast, in soils not amended with nutrients, inoculation of donors in the A horizon and subsequent formation of transconjugants (105 CFU/g of soil) could not increase the 2,4-D degradation rate compared to that of the noninoculated soil. However, donor inoculation in the nonamended B-horizon soil resulted in complete degradation of 2,4-D within 19 days, while no degradation at all was observed in noninoculated soil during 89 days. With plasmid pEMT1, this enhanced degradation seemed to be due only to transconjugants (105 CFU/g of soil), since the donor was already undetectable when degradation started. Denaturing gradient gel electrophoresis (DGGE) of 16S rRNA genes showed that inoculation of the donors was followed by a shift in the microbial community structure of the nonamended B-horizon soils. The new 16S rRNA gene fragments in the DGGE profile corresponded with the 16S rRNA genes of 2,4-D-degrading transconjugant colonies isolated on agar plates. This result indicates that the observed change in the community was due to proliferation of transconjugants formed in soil. Overall, this work clearly demonstrates that bioaugmentation can constitute an effective strategy for cleanup of soils which are poor in nutrients and microbial activity

  15. Chlorophenol hydroxylases encoded by plasmid pJP4 differentially contribute to chlorophenoxyacetic acid degradation.

    PubMed

    Ledger, T; Pieper, D H; González, B

    2006-04-01

    Phenoxyalkanoic compounds are used worldwide as herbicides. Cupriavidus necator JMP134(pJP4) catabolizes 2,4-dichlorophenoxyacetate (2,4-D) and 4-chloro-2-methylphenoxyacetate (MCPA), using tfd functions carried on plasmid pJP4. TfdA cleaves the ether bonds of these herbicides to produce 2,4-dichlorophenol (2,4-DCP) and 4-chloro-2-methylphenol (MCP), respectively. These intermediates can be degraded by two chlorophenol hydroxylases encoded by the tfdB(I) and tfdB(II) genes to produce the respective chlorocatechols. We studied the specific contribution of each of the TfdB enzymes to the 2,4-D/MCPA degradation pathway. To accomplish this, the tfdB(I) and tfdB(II) genes were independently inactivated, and growth on each chlorophenoxyacetate and total chlorophenol hydroxylase activity were measured for the mutant strains. The phenotype of these mutants shows that both TfdB enzymes are used for growth on 2,4-D or MCPA but that TfdB(I) contributes to a significantly higher extent than TfdB(II). Both enzymes showed similar specificity profiles, with 2,4-DCP, MCP, and 4-chlorophenol being the best substrates. An accumulation of chlorophenol was found to inhibit chlorophenoxyacetate degradation, and inactivation of the tfdB genes enhanced the toxic effect of 2,4-DCP on C. necator cells. Furthermore, increased chlorophenol production by overexpression of TfdA also had a negative effect on 2,4-D degradation by C. necator JMP134 and by a different host, Burkholderia xenovorans LB400, harboring plasmid pJP4. The results of this work indicate that codification and expression of the two tfdB genes in pJP4 are important to avoid toxic accumulations of chlorophenols during phenoxyacetic acid degradation and that a balance between chlorophenol-producing and chlorophenol-consuming reactions is necessary for growth on these compounds. PMID:16597983

  16. Dose rate effects on array CCDs exposed by Co-60 γ rays induce saturation output degradation and annealing tests

    SciTech Connect

    Wang, Zujun Chen, Wei; He, Baoping; Yao, Zhibin; Xiao, Zhigang; Sheng, Jiangkun; Liu, Minbo

    2015-10-15

    The experimental tests of dose rate and annealing effects on array charge-coupled devices (CCDs) are presented. The saturation output voltage (V{sub S}) versus the total dose at the dose rates of 0.01, 0.1, 1.0, 10.0 and 50 rad(Si)/s are compared. Annealing tests are performed to eliminate the time-dependent effects. The V{sub S} degradation levels depend on the dose rates. The V{sub S} degradation mechanism induced by dose rate and annealing effects is analyzed. The V{sub S} at 20 krad(Si) with the dose rate of 0.03 rad(Si)/s are supplemented to assure the degradation curves between the dose rates of 0.1 and 0.01 rad(Si)/s. The CCDs are divided into two groups, with one group biased and the other unbiased during {sup 60}Co γ radiation. The V{sub S} degradation levels of the biased CCDs during radiation are more severe than that of the unbiased CCDs.

  17. Degradation of sunscreen agent p-aminobenzoic acid using a combination system of UV irradiation, persulphate and iron(II).

    PubMed

    Xue, Yicen; Dong, Wenbo; Wang, Xiaoning; Bi, Wenlong; Zhai, Pingping; Li, Hongjing; Nie, Minghua

    2016-03-01

    Increased usage and discharge of sunscreens have led to ecological safety crisis, and people are developing the advanced oxidation processes (AOPs) to treat them. The present study aimed to determine the degradation efficiency and mechanism of the sunscreen agent p-aminobenzoic acid (PABA) using the UV/Fe(2+)/persulphate (PS) method. A series of irradiation experiments were conducted to optimise the system conditions and to study the impacts of the natural anion. Free radicals and degradation products were identified in order to clarify the degradation mechanism. Initial PS and Fe(2+) concentrations showed significant impacts on PABA degradation. Natural anions, such as Cl(-), NO3 (-), H2PO4 (-) and HCO3 (-), impeded PABA degradation because of ion (Fe(2+)) capture, radical scavenging or pH effects. Hydroxyl (HO·) and sulphate (SO4 (·-)) radicals were two main radicals observed in the UV/Fe(2+)/PS system; of these, SO4 (·-) showed greater effects on PABA degradation. Over 99 % of the available PABA was completely degraded into carbon dioxide (CO2) and water (H2O) by the UV/Fe(2+)/PS system, and the remaining PABA participated in complex radical reactions. By-products were identified by total ion chromatography and mass spectrometry. Our research provides a treatment process for PABA with high degradation efficiency and environmental safety and introduces a new strategy for sunscreen degradation. PMID:26517998

  18. Functional characterization of normal and degraded bovine meniscus: rate-dependent indentation and friction studies.

    PubMed

    Baro, Vincent J; Bonnevie, Edward D; Lai, Xiaohan; Price, Christopher; Burris, David L; Wang, Liyun

    2012-08-01

    The menisci are known to play important roles in normal joint function and the development of diseases such as osteoarthritis. However, our understanding of meniscus' load bearing and lubrication properties at the tissue level remains limited. The objective of this investigation was to characterize the site- and rate-dependency of the compressive and frictional responses of the meniscus under a spherical contact load. Using a custom testing device, indentation tests with rates of 1, 10, 25, 50, and 100μm/s were performed on bovine medial meniscus explants, which were harvested from five locations including the femoral apposing surface at the anterior, central, and posterior locations and the central portion at the deep layer and at the tibial apposing surface (n=5 per location). Sliding tests with rates of 0.05, 0.25, 1, and 5mm/s were performed on the central femoral aspect and central tibial aspect superficial samples (n=6 per location). A separate set of superficial samples were subjected to papain digestion and tested prior to and post treatment. Our findings are: i) the Hertz contact model can be used to fit the force responses of meniscus under the conditions tested; ii) the anterior region is significantly stiffer than the posterior region and tissue modulus does not vary with tissue depth at the central region; iii) the friction coefficient of the meniscus is on the order of 0.02 under migratory contacts and the femoral apposing surface tends to show lower friction than the tibial apposing surface; iv) the meniscus exhibits increased modulus and lubrication with increased indentation and sliding rates; v) matrix degradation impedes the functional load support and lubrication properties of the tissue. The site- and rate-dependent properties of the meniscus may be attributed to spatial variations of the tissue's biphasic structure. These properties substantiate the role of the meniscus as one of the important bearing surfaces of the knee. These data

  19. Jasmonate-inducible plant enzymes degrade essential amino acids in the herbivore midgut

    PubMed Central

    Chen, Hui; Wilkerson, Curtis G.; Kuchar, Jason A.; Phinney, Brett S.; Howe, Gregg A.

    2005-01-01

    The plant hormone jasmonic acid (JA) activates host defense responses against a broad spectrum of herbivores. Although it is well established that JA controls the expression of a large set of target genes in response to tissue damage, very few gene products have been shown to play a direct role in reducing herbivore performance. To test the hypothesis that JA-inducible proteins (JIPs) thwart attack by disrupting digestive processes in the insect gut, we used a MS-based approach to identify host proteins that accumulate in the midgut of Manduca sexta larvae reared on tomato (Solanum lycopersicum) plants. We show that two JIPs, arginase and threonine deaminase (TD), act in the M. sexta midgut to catabolize the essential amino acids Arg and Thr, respectively. Transgenic plants that overexpress arginase were more resistant to M. sexta larvae, and this effect was correlated with reduced levels of midgut Arg. We present evidence indicating that the ability of TD to degrade Thr in the midgut is enhanced by herbivore-induced proteolytic removal of the enzyme's C-terminal regulatory domain, which confers negative feedback regulation by isoleucine in planta. Our results demonstrate that the JA signaling pathway strongly influences the midgut protein content of phytophagous insects and support the hypothesis that catabolism of amino acids in the insect digestive tract by host enzymes plays a role in plant protection against herbivores. PMID:16357201

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

    PubMed

    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

  1. Visible light caffeic acid degradation by carbon-doped titanium dioxide.

    PubMed

    Venditti, Francesco; Cuomo, Francesca; Ceglie, Andrea; Avino, Pasquale; Russo, Mario Vincenzo; Lopez, Francesco

    2015-03-31

    The removal of the phenolic compound, caffeic acid, by photodegradation has been investigated using carbon-doped titanium dioxide particles as a photocatalyst under visible light. UV-vis absorption spectroscopy and gas chromatography-ion trap mass spectrometry analyses revealed a substrate concentration dependence of the removal of caffeic acid from a water solution. The k2 and t(0.5) parameters of each reaction were calculated by fitting kinetics data to a second-order kinetic adsorption model. To evaluate the photodegradation event, the effect of the adsorption process on the whole degradation was also monitored in the absence of light. Adsorption isotherm studies supported by ζ potential and scanning electron microscopy data demonstrated the pivotal role of the absorption mechanism. It was found that the whole photodegradation process is governed by a synergic mechanism in which adsorption and photodegradation are involved. This study, centered on the removal of caffeic acid from aqueous solutions, highlights the potential application of this technology for the elimination of phenolic compounds from olive mill wastewater, a fundamental goal in both the agronomical and environmental fields. PMID:25763603

  2. Energetics and kinetics of anaerobic aromatic and fatty acid degradation. Progress report, June 1991--November 1992

    SciTech Connect

    McInerney, M.J.

    1992-11-16

    The kinetics of benzoate degradation by the anaerobic syntrophic bacterium, Syntrophus buswellii, was studied in coculture with Desulfovibrio strain G11. The threshold value for benzoate degradation was dependent on the acetate concentration with benzoate threshold values ranging from 2.4 {mu}M at 20 mM acetate to 30.0 {mu}M at 65 mM acetate. Increasing acetate concentrations also inhibited the rate of benzoate degradation with a apparent K{sub i} for acetate inhibition of 7.0 mM. Lower threshold values were obtained when nitrate rather than sulfate was the terminal electron acceptor. These data are consistent with a thermodynamic explanation for the threshold, and suggest that there is a minimum Gibbs free energy value required for the degradation of benzoate. An acetoacetyl-CoA thiolase has been isolated from Syntrophomonas wolfei; it is apparently a key enzyme controlling the synthesis of poly-B-hydroxyalkanoate from acetyl-CoA in this organism. Kinetic characterization of the acetoacetyl-CoA thiolase from S. wolfei showed that it is similar in its structural, kinetic, and apparent regulatory properties to other biosynthetic acetoacetyl-CoA thiolases from phylogenetically distinct bacteria that synthesize PHA. Intracellular concentrations of CoA and acetyl-CoA are believed to be critical factors regulating the activity of the acetoacetyl-CoA thiolase in S. wolfei. We have also isolated and characterized several new halophilic anaerobic fermentative anaerobes. Phylogenetic analysis indicates that one of these bacteria is a new species in the genus, Haloanaerobium. Two other species appear to be members of the genus, Halobacteroides. Several halophilic acetoclastic methanogenic bacteria have also been isolated and their physiological properties are currently under investigation. We have also isolated an acetate-using dissimilatory iron-reducing bacterium.

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

    PubMed

    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

  4. High emission rate of sulfuric acid from Bezymianny volcano, Kamchatka

    NASA Astrophysics Data System (ADS)

    Zelenski, Michael; Taran, Yuri; Galle, Bo

    2015-09-01

    High concentrations of primary sulfuric acid (H2SO4) in fumarolic gases and high emission rate of sulfuric acid aerosol in the plume were measured at Bezymianny volcano, an active dome-growing andesitic volcano in central Kamchatka. Using direct sampling, filter pack sampling, and differential optical absorption spectroscopy measurements, we estimated an average emission of H2SO4 at 243 ± 75 t/d in addition to an average SO2 emission of 212 ± 65 t/d. The fumarolic gases of Bezymianny correspond to arc gases released by several magma bodies at different stages of degassing and contain 25-92% of entrained air. H2SO4 accounts for 6-87 mol% of the total sulfur content, 42.8 mol% on average, and SO2 is the rest. The high H2SO4 in Bezymianny fumaroles can be explained by catalytic oxidation of SO2 inside the volcanic dome. Because sulfate aerosol is impossible to measure remotely, the total sulfur content in a plume containing significant H2SO4 may be seriously underestimated.

  5. Uncertainty in degradation rates for organic micro-pollutants during full-scale sewage sludge composting.

    PubMed

    Sadef, Yumna; Poulsen, Tjalfe G; Habib, Kashif; Iqbal, Tariq; Nizami, Abdul Sattar

    2016-10-01

    Composting can potentially remove organic pollutants in sewage sludge. When estimating pollutant removal efficiency, knowledge of estimate uncertainty is important for understanding estimate reliability. In this study the uncertainty (coefficient of variation, CV) in pollutant degradation rate (K1) and relative concentration at 35days of composting (C35/C0) was evaluated. This was done based on recently presented pollutant concentration data, measured under full-scale composting conditions using two different sampling methods for a range of organic pollutants commonly found in sewage sludge. Non-parametric statistical procedures were used to estimate CV values for K1 and C35/C0 for individual pollutants. These were then used to compare the two sampling methods with respect to CV and to determine confidence intervals for average CV. Results showed that sampling method is crucial for reducing uncertainty. The results further indicated that it is possible to achieve CV values for both K1 and C35/C0 of about 15%. PMID:27342191

  6. Influence of the intramedullary nail preparation method on nail's mechanical properties and degradation rate.

    PubMed

    Morawska-Chochół, Anna; Chłopek, Jan; Szaraniec, Barbara; Domalik-Pyzik, Patrycja; Balacha, Ewa; Boguń, Maciej; Kucharski, Rafael

    2015-06-01

    When it comes to the treatment of long bone fractures, scientists are still investigating new materials for intramedullary nails and different manufacturing methods. Some of the most promising materials used in the field are resorbable polymers and their composites, especially since there is a wide range of potential manufacturing and processing methods. The aim of this work was to select the best manufacturing method and technological parameters to obtain multiphase, and multifunctional, biodegradable intramedullary nails. All composites were based on a poly(l-lactide) matrix. Either magnesium alloy wires or carbon and alginate fibres were introduced in order to reinforce the nails. The polylactide matrix was also modified with tricalcium phosphate and gentamicin sulfate. The composite nails were manufactured using three different methods: forming from solution, injection moulding and hot pressing. The effect of each method of manufacturing on mechanical properties and degradation rate of the nails was evaluated. The study showed that injection moulding provides higher uniformity and homogeneity of the particle-modified polylactide matrix, whereas hot pressing favours applying higher volume fractions of fibres and their better impregnation with the polymer matrix. Thus, it was concluded that the fabrication method should be individually selected dependently on the nail's desired phase composition. PMID:25842113

  7. Biochemical and structural characterization of Klebsiella pneumoniae oxamate amidohydrolase in the uric acid degradation pathway.

    PubMed

    Hicks, Katherine A; Ealick, Steven E

    2016-06-01

    HpxW from the ubiquitous pathogen Klebsiella pneumoniae is involved in a novel uric acid degradation pathway downstream from the formation of oxalurate. Specifically, HpxW is an oxamate amidohydrolase which catalyzes the conversion of oxamate to oxalate and is a member of the Ntn-hydrolase superfamily. HpxW is autoprocessed from an inactive precursor to form a heterodimer, resulting in a 35.5 kDa α subunit and a 20 kDa β subunit. Here, the structure of HpxW is presented and the substrate complex is modeled. In addition, the steady-state kinetics of this enzyme and two active-site variants were characterized. These structural and biochemical studies provide further insight into this class of enzymes and allow a mechanism for catalysis consistent with other members of the Ntn-hydrolase superfamily to be proposed. PMID:27303801

  8. Edible fungus degrade bisphenol A with no harmful effect on its fatty acid composition.

    PubMed

    Zhang, Chengdong; Li, Mingzhu; Chen, Xiaoyan; Li, Mingchun

    2015-08-01

    Bisphenol A (BPA) is an endocrine-disrupting chemical that is ubiquitous in the environment because of its broad industrial use. The authors report that the most widely cultivated mushroom in the world (i.e., white-rot fungus, Pleurotus ostreatus) efficiently degraded 10mg/L of BPA in 7 days. Extracellular laccase was identified as the enzyme responsible for this activity. LC-MS analysis of the metabolites revealed the presence of both low- and high-molecular-weight products obtained via oxidative cleavage and coupling reactions, respectively. In particular, an analysis of the fatty acid composition and chemical structure of the fungal mycelium demonstrated that exposure to BPA resulted in no harmful effects on this edible fungus. The results provide a better understanding of the environmental fate of BPA and its potential impact on food crops. PMID:25933259

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

    PubMed

    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

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

    SciTech Connect

    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.

  11. Effects of D-amino acid substituents on degradation of LHRH analogues by proximal tubule

    SciTech Connect

    Flouret, G.; Majewski, T.; Peterson, D.R.; Kenny, A.J.; Carone, F.A.

    1987-03-01

    The luteinizing hormone-releasing hormone, LHRH, is degraded in renal proximal tubules (PT) in vivo (rat) and in vitro (rabbit) to < Glu-His (2), < Glu-His-Trp (3), and < Glu-His-Trp-Ser (4). LHRH may be cleaved by endopeptidases simultaneously at multiple bonds, or initially at Ser/sup 4/-Try/sup 5/ followed by carboxypeptidase hydrolysis of 4 to 3 and then 2. To distinguish between these mechanisms, (/sup 3/H)LHRH analogues were incubated with rabbit renal brush-border membranes (BBM), microinfused into PT in vivo or in vitro, and products were analyzed by HPLC. (D-Ser/sup 4/)LHRH was not cleaved at D-Ser/sup 4/-Try/sup 5/ but yielded < Glu-His-Trp-D-Ser-Tyr-Gly as the major metabolite plus 2 and 3. (D-Trp/sup 6/)LHRH was cleaved by BBM and PT to 2 and 3, but not to 4. (D-Ser/sup 4/, D-Trp/sup 6/)LHRH was not cleaved by BBM, but was degraded to 2 by PT in vivo. Thus, D-amino acid substituents altered the expected cleavage pattern of these analogues. Thus, normally LHRH may be cleaved in PT by endopeptidase-24.11 to 2 and 4, and by angiotensin I-converting enzyme to 3, its know cleavage site.

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

    PubMed

    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

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

    PubMed Central

    2010-01-01

    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. sticklandii genome and

  14. Quantifying Protein Synthesis and Degradation in Arabidopsis by Dynamic 13CO2 Labeling and Analysis of Enrichment in Individual Amino Acids in Their Free Pools and in Protein1[OPEN

    PubMed Central

    Fernie, Alisdair R.; Stitt, Mark

    2015-01-01

    Protein synthesis and degradation represent substantial costs during plant growth. To obtain a quantitative measure of the rate of protein synthesis and degradation, we supplied 13CO2 to intact Arabidopsis (Arabidopsis thaliana) Columbia-0 plants and analyzed enrichment in free amino acids and in amino acid residues in protein during a 24-h pulse and 4-d chase. While many free amino acids labeled slowly and incompletely, alanine showed a rapid rise in enrichment in the pulse and a decrease in the chase. Enrichment in free alanine was used to correct enrichment in alanine residues in protein and calculate the rate of protein synthesis. The latter was compared with the relative growth rate to estimate the rate of protein degradation. The relative growth rate was estimated from sequential determination of fresh weight, sequential images of rosette area, and labeling of glucose in the cell wall. In an 8-h photoperiod, protein synthesis and cell wall synthesis were 3-fold faster in the day than at night, protein degradation was slow (3%–4% d−1), and flux to growth and degradation resulted in a protein half-life of 3.5 d. In the starchless phosphoglucomutase mutant at night, protein synthesis was further decreased and protein degradation increased, while cell wall synthesis was totally inhibited, quantitatively accounting for the inhibition of growth in this mutant. We also investigated the rates of protein synthesis and degradation during leaf development, during growth at high temperature, and compared synthesis rates of Rubisco large and small subunits of in the light and dark. PMID:25810096

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

    PubMed Central

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

    2016-01-01

    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

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

    PubMed

    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

  17. Nitrogen mineralization rates of the acidic, xeric soils of the New Jersey Pinelands: field rates

    SciTech Connect

    Poovarodom, S.; Tate, R.L. III; Bloom, R.A.

    1988-04-01

    Using the buried-bag procedure, the authors quantified nitrogen mineralization rates in the xeric, acidic Lakehurst, and Atsion sands of the New Jersey Pine Barrens. Average annual nitrogen yields in the upper 15 cm for the Lakehurst and the Atsion sands were 38.4 and 53.0 kg N/ha, corresponding to 4.5 and 2.5% of the total nitrogen, respectively. Net nitrogen mineralization in both soils exhibited distinct seasonal patterns with maxima in summer and minimum rates in the winter. Nitrification accounted for only 5% of the total N mineralized in both soils. This is consistent with the finding of low populations of autotrophic nitrifiers in these soils.

  18. Degradation Kinetics of VX

    SciTech Connect

    Gary S. Groenewold

    2010-12-01

    O-ethyl S-(2-diisopropylaminoethyl)phosphonothiolate (VX) is the most toxic of the conventional chemical warfare agents. It is a persistent compound, an attribute derived from its relative involatility and slow rates of hydrolysis. These properties suggest that VX can linger in an exposed environment for extended periods of time long after the air has cleared. Concern over prolonged risk from VX exposure is exacerbated by the fact that it poses a dermal contact hazard. Hence a detailed understanding of volatilization rates, and degradation pathways and rates occurring in various environments is needed. Historically, volatilization has not been considered to be an important mechanism for VX depletion, but recent studies have shown that a significant fraction of VX may volatilize, depending on the matrix. A significant body of research has been conducted over the years to unravel VX degradation reaction pathways and to quantify the rates at which they proceed. Rigorous measurement of degradation rates is frequently difficult, and thus in many cases the degradation of VX has been described in terms of half lives, while in fewer instances rate constants have been measured. This variable approach to describing degradation kinetics reflects uncertainty regarding the exact nature of the degradation mechanisms. In this review, rates of VX degradation are compared on the basis of pseudo-first order rate constants, in order to provide a basis for assessing likelihood of VX persistence in a given environment. An issue of specific concern is that one VX degradation pathway produces S-2-(diisopropylaminoethyl) methylphosphonothioic acid (known as EA2192), which is a degradation product that retains much of the original toxicity of VX. Consequently degradation pathways and rates for EA2192 are also discussed.

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

    PubMed Central

    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

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

    PubMed

    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

  1. Degradation of dissolved organic monomers and short-chain fatty acids in sandy marine sediment by fermentation and sulfate reduction

    NASA Astrophysics Data System (ADS)

    Valdemarsen, Thomas; Kristensen, Erik

    2010-03-01

    The decay of a wide range of organic monomers (short-chain volatile fatty acids (VFA's), amino acids, glucose and a pyrimidine) was studied in marine sediments using experimental plug flow-through reactors. The reactions were followed in the presence and absence of 10 mM SO 42-. Degradation stoichiometry of individual monomers (inflow concentration of 6 mM organic C) was traced by measuring organic (VFA's, amino acids) and inorganic (CO 2, NH 4+, SO 42-) compounds in the outflow. Fermentation of amino acids was efficient and complete during passage through anoxic sediment reactors. Aliphatic amino acids (alanine, serine and glutamate) were primarily recovered as CO 2 (24-34%), formate (3-22%) and acetate (41-83%), whereas only ˜1/3 of the aromatic amino acid (tyrosine) was recovered as CO 2 (13%) and acetate (20%). Fermentation of glucose and cytosine was also efficient (78-86%) with CO 2 (30-35%), formate (3%) and acetate (28-33%) as the primary products. Fermentation of VFA's (acetate, propionate and butyrate), on the other hand, appeared to be product inhibited. The presence of SO 42- markedly stimulated VFA degradation (29-45% efficiency), and these compounds were recovered as CO 2 (17% for butyrate to 100% for acetate) and acetate (51% and 82% for propionate and butyrate, respectively). When reaction stoichiometry during fermentation is compared with compound depletion during sulfate reduction, the higher proportion CO 2 recovery is consistent with lower acetate and formate accumulation. Our results therefore suggest that fermentation reactions mediate the initial degradation of added organic compounds, even during active sulfate reduction. Fermentative degradation stoichiometry also suggested significant H 2 production, and >50% of sulfate reduction appeared to be fuelled by H 2. Furthermore, our results suggest that fermentation was the primary deamination step during degradation of the amino acids and cytosine.

  2. Wood source and pyrolysis temperature interact to control PyOM degradation rates

    NASA Astrophysics Data System (ADS)

    Bird, J. A.; Hatton, P. J.; Filley, T. R.; Chatterjee, S.; Auclerc, A.; Gormley, M.; Dastmalchi, K.; Stark, R. E.; Nadelhoffer, K. J.

    2015-12-01

    Surprisingly little is known about how shifts in tree species composition and increased forest fire frequency and intensity will affect one of the most stable pools of soil organic matter, i.e. the pyrogenic organic matter (PyOM or char). In a previous study, we showed that wood source and pyrolysis temperature interact to control PyOM structure and potential reactivity for two tree species common in high-latitude forests, jack pine (JP) and red maple (RM). Here, we investigate whether these differences affect PyOM turnover by examining the fates of 13C/15N-enriched JP wood and PyOM pyrolyzed at 300 (JP300) and 450 °C (JP450) and RM pyrolyzed at 450 °C (RM450). The substrates were applied 1-3 cm below the O/A interface of a well-drained Spodosol in a long-term forest fire study located at the University of Michigan Biological Station (Pellston, MI, USA). 13C-CO2effluxes from the first 996 days of decay showed a significant wood source by pyrolysis temperature interaction on PyOM field mineralisation rates, with RM450 mineralising twice faster than JP450 during the first 90 days. Increasing pyrolysis temperature substantially decreased field mineralization rates during the first 996 days, with mineralisation rates 24 and 80 times slower for JP300 and JP450 compared with JP wood. After 1 year, (i) bacterial groups were large sinks for PyOM-derived C as pyrolysis temperature increased and as substrate use efficiency decreased; (ii) potential phenol oxidase and net peroxidase activities were unaffected by the PyOM addition, although net peroxidase activities measured tended to lesser for soils amended with JP450 and RM450; and (iii) Collembola detritivores appeared less likely to be found for soils amended with JP450 and RM450. PyOM-derived C and N recoveries did not differ after 1 year; we will present 3-y recovery data. Our results suggest that the composition of angiosperms (e.g. RM) and gymnosperms (e.g. JP) in high-latitude forests is an underappreciated but

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

    PubMed Central

    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

  4. Effect of height and orientation ( microclimate) on geomorphic degradation rates and processes, late-glacial terrace scarps in central Idaho

    USGS Publications Warehouse

    Pierce, K.L.; Colman, Steven M.

    1986-01-01

    Examines the effects of scarp size (height) and orientation (microclimate) by keeping constant variables such as age, lithology, and regional climate. For scarps 2m high, the degradation rate on S-facing scarps is 2 times that on N-facing scarps; for 10-m scarps, it is 5 times. Scarp morphology may be used to estimate age. -from Authors

  5. Chemical evolution of RNA under hydrothermal conditions and the role of thermal copolymers of amino acids for the prebiotic degradation and formation of RNA

    NASA Astrophysics Data System (ADS)

    Kawamura, K.; Nagahama, M.; Kuranoue, K.

    The roles of thermal copolymers of amino acids (TCAA) were studied for the prebiotic degradation of RNA. A weak catalytic ability of TCAA consisted of Glu, L-Ala, L-Val, L-Glu, L-Asp, and optionally L-His was detected for the cleavage of the ribose phosphodiester bond of a tetranucleotide (5'-dCrCdGdG) in aqueous solution at 80 °C. The rate constants of the disappearance of 5'-dCrCdGdG were determined in aqueous solutions using different pH buffer and TCAA. The degradation rates were enhanced 1.3-3.0 times in the presence of TCAA at pH 7.5 and 8.0 at 80 °C, while the hydrolysis of oligoguanylate (oligo(G)) was accelerated about 1.6 times at pH 8.0. A weak inhibitory activity for the cleavage of oligo(G) was detected in the presence of 0.055 M TCAA-Std. On the other hand, our recent study on the influences of TCAA for the template-directed reaction of oligo(G) on a polycytidylic acid template showed that TCAA has an acceleration activity for the degradation of the activated nucleotide monomer and an acceleration activity for the formation of G 5' ppG capped oligo(G). This series of studies suggest that efficient and selective catalytic or inhibitory activities for either the degradation or formation of RNA under hydrothermal conditions could have hardly emerged from the simple thermal condensation products of amino acids. A scenario is going to be deduced on the chemical evolution of enzymatic activities and RNA molecules concerning hydrothermal earth conditions.

  6. Chemical evolution of RNA under hydrothermal conditions and the role of thermal copolymers of amino acids for the prebiotic degradation and formation of RNA

    NASA Technical Reports Server (NTRS)

    Kawamura, K.; Nagahama, M.; Kuranoue, K.

    2005-01-01

    The roles of thermal copolymers of amino acids (TCAA) were studied for the prebiotic degradation of RNA. A weak catalytic ability of TCAA consisted of Glu, L-Ala, L-Val, L-Glu, L-Asp, and optionally L-His was detected for the cleavage of the ribose phosphodiester bond of a tetranucleotide (5'-dCrCdGdG) in aqueous solution at 80 degees C. The rate constants of the disappearance of 5'-dCrCdGdG were determined in aqueous solutions using different pH buffer and TCAA. The degradation rates were enhanced 1.3-3.0 times in the presence of TCAA at pH 7.5 and 8.0 at 80 degrees C, while the hydrolysis of oligoguanylate (oligo(G)) was accelerated about 1.6 times at pH 8.0. A weak inhibitory activity for the cleavage of oligo(G) was detected in the presence of 0.055 M TCAA-Std. On the other hand, our recent study on the influences of TCAA for the template-directed reaction of oligo(G) on a polycytidylic acid template showed that TCAA has an acceleration activity for the degradation of the activated nucleotide monomer and an acceleration activity for the formation of G5' ppG capped oligo(G). This series of studies suggest that efficient and selective catalytic or inhibitory activities for either the degradation or formation of RNA under hydrothermal conditions could have hardly emerged from the simple thermal condensation products of amino acids. A scenario is going to be deduced on the chemical evolution of enzymatic activities and RNA molecules concerning hydrothermal earth conditions. c2005 COSPAR. Published by Elsevier Ltd. All rights reserved.

  7. Sequential photochemical and microbial degradation of organic molecules bound to humic acid

    SciTech Connect

    Amador, J.A.; Zika, R.G. ); Alexander, M. )

    1989-11-01

    We studied the effects of photochemical processes on the mineralization by soil microorganisms of (2-{sup 14}C)glycine bound to soil humic acid. Microbial mineralization of these complexes in the dark increased inversely with the molecular weight of the complex molecules. Sunlight irradiation of glycine-humic acid complexes resulted in loss of absorbance in the UV range and an increase in the amount of {sup 14}C-labeled low-molecular-weight photoproducts and the rate and extent of mineralization. More than half of the radioactivity in the low-molecular-weight photoproducts appears to be associated with carboxylic acids. Microbial mineralization of the organic carbon increased with solar flux and was proportional to the loss of A{sub 330}. Mineralization was proportional to the percentage of the original complex that was converted to low-molecular-weight photoproducts. Only light at wavelengths below 380 nm had an effect on the molecular weight distribution of the products formed from the glycine-humic acid complexes and on the subsequent microbial mineralization. Our results indicate that photochemical processes generate low-molecular-weight, readily biodegradable molecules from high-molecular-weight complexes of glycine with humic acid.

  8. Sequential photochemical and microbial degradation of organic molecules bound to humic Acid.

    PubMed

    Amador, J A; Alexander, M; Zika, R G

    1989-11-01

    We studied the effects of photochemical processes on the mineralization by soil microorganisms of [2-C]glycine bound to soil humic acid. Microbial mineralization of these complexes in the dark increased inversely with the molecular weight of the complex molecules. Sunlight irradiation of glycine-humic acid complexes resulted in loss of absorbance in the UV range and an increase in the amount of C-labeled low-molecular-weight photoproducts and the rate and extent of mineralization. More than half of the radioactivity in the low-molecular-weight photoproducts appears to be associated with carboxylic acids. Microbial mineralization of the organic carbon increased with solar flux and was proportional to the loss of A(330). Mineralization was proportional to the percentage of the original complex that was converted to low-molecular-weight photoproducts. Only light at wavelengths below 380 nm had an effect on the molecular weight distribution of the products formed from the glycine-humic acid complexes and on the subsequent microbial mineralization. Our results indicate that photochemical processes generate low-molecular-weight, readily biodegradable molecules from high-molecular-weight complexes of glycine with humic acid. PMID:16348046

  9. Sequential Photochemical and Microbial Degradation of Organic Molecules Bound to Humic Acid

    PubMed Central

    Amador, José A.; Alexander, Martin; Zika, Rod G.

    1989-01-01

    We studied the effects of photochemical processes on the mineralization by soil microorganisms of [2-14C]glycine bound to soil humic acid. Microbial mineralization of these complexes in the dark increased inversely with the molecular weight of the complex molecules. Sunlight irradiation of glycine-humic acid complexes resulted in loss of absorbance in the UV range and an increase in the amount of 14C-labeled low-molecular-weight photoproducts and the rate and extent of mineralization. More than half of the radioactivity in the low-molecular-weight photoproducts appears to be associated with carboxylic acids. Microbial mineralization of the organic carbon increased with solar flux and was proportional to the loss of A330. Mineralization was proportional to the percentage of the original complex that was converted to low-molecular-weight photoproducts. Only light at wavelengths below 380 nm had an effect on the molecular weight distribution of the products formed from the glycine-humic acid complexes and on the subsequent microbial mineralization. Our results indicate that photochemical processes generate low-molecular-weight, readily biodegradable molecules from high-molecular-weight complexes of glycine with humic acid. PMID:16348046

  10. Optimal Cultivation Time for Yeast and Lactic Acid Bacteria in Fermented Milk and Effects of Fermented Soybean Meal on Rumen Degradability Using Nylon Bag Technique.

    PubMed

    Polyorach, S; Poungchompu, O; Wanapat, M; Kang, S; Cherdthong, A

    2016-09-01

    The objectives of this study were to determine an optimal cultivation time for populations of yeast and lactic acid bacteria (LAB) co-cultured in fermented milk and effects of soybean meal fermented milk (SBMFM) supplementation on rumen degradability in beef cattle using nylon bag technique. The study on an optimal cultivation time for yeast and LAB growth in fermented milk was determined at 0, 4, 8, 24, 48, 72, and 96 h post-cultivation. After fermenting for 4 days, an optimal cultivation time of yeast and LAB in fermented milk was selected and used for making the SBMFM product to study nylon bag technique. Two ruminal fistulated beef cattle (410±10 kg) were used to study on the effect of SBMFM supplementation (0%, 3%, and 5% of total concentrate substrate) on rumen degradability using in situ method at incubation times of 0, 2, 4, 6, 12, 24, 48, and 72 h according to a Completely randomized design. The results revealed that the highest yeast and LAB population culture in fermented milk was found at 72 h-post cultivation. From in situ study, the soluble fractions at time zero (a), potential degradability (a+b) and effective degradability of dry matter (EDDM) linearly (p<0.01) increased with the increasing supplemental levels and the highest was in the 5% SBMFM supplemented group. However, there was no effect of SBMFM supplement on insoluble degradability fractions (b) and rate of degradation (c). In conclusion, the optimal fermented time for fermented milk with yeast and LAB was at 72 h-post cultivation and supplementation of SBMFM at 5% of total concentrate substrate could improve rumen degradability of beef cattle. However, further research on effect of SBMFM on rumen ecology and production performance in meat and milk should be conducted using in vivo both digestion and feeding trials. PMID:26954119

  11. Optimal Cultivation Time for Yeast and Lactic Acid Bacteria in Fermented Milk and Effects of Fermented Soybean Meal on Rumen Degradability Using Nylon Bag Technique

    PubMed Central

    Polyorach, S.; Poungchompu, O.; Wanapat, M.; Kang, S.; Cherdthong, A.

    2016-01-01

    The objectives of this study were to determine an optimal cultivation time for populations of yeast and lactic acid bacteria (LAB) co-cultured in fermented milk and effects of soybean meal fermented milk (SBMFM) supplementation on rumen degradability in beef cattle using nylon bag technique. The study on an optimal cultivation time for yeast and LAB growth in fermented milk was determined at 0, 4, 8, 24, 48, 72, and 96 h post-cultivation. After fermenting for 4 days, an optimal cultivation time of yeast and LAB in fermented milk was selected and used for making the SBMFM product to study nylon bag technique. Two ruminal fistulated beef cattle (410±10 kg) were used to study on the effect of SBMFM supplementation (0%, 3%, and 5% of total concentrate substrate) on rumen degradability using in situ method at incubation times of 0, 2, 4, 6, 12, 24, 48, and 72 h according to a Completely randomized design. The results revealed that the highest yeast and LAB population culture in fermented milk was found at 72 h-post cultivation. From in situ study, the soluble fractions at time zero (a), potential degradability (a+b) and effective degradability of dry matter (EDDM) linearly (p<0.01) increased with the increasing supplemental levels and the highest was in the 5% SBMFM supplemented group. However, there was no effect of SBMFM supplement on insoluble degradability fractions (b) and rate of degradation (c). In conclusion, the optimal fermented time for fermented milk with yeast and LAB was at 72 h-post cultivation and supplementation of SBMFM at 5% of total concentrate substrate could improve rumen degradability of beef cattle. However, further research on effect of SBMFM on rumen ecology and production performance in meat and milk should be conducted using in vivo both digestion and feeding trials. PMID:26954119

  12. Clostridium thermocellum releases coumaric acid during degradation of untreated grasses by the action of an unknown enzyme.

    PubMed

    Herring, Christopher D; Thorne, Philip G; Lynd, Lee R

    2016-03-01

    Clostridium thermocellum is an anaerobic thermophile with the ability to digest lignocellulosic biomass that has not been pretreated with high temperatures. Thermophilic anaerobes have previously been shown to more readily degrade grasses than wood. Part of the explanation for this may be the presence of relatively large amounts of coumaric acid in grasses, with linkages to both hemicellulose and lignin. We found that C. thermocellum and cell-free cellulase preparations both release coumaric acid from bagasse and switchgrass. Cellulase preparations from a mutant strain lacking the scaffoldin cipA still showed activity, though diminished. Deletion of all three proteins in C. thermocellum with ferulic acid esterase domains, either singly or in combination, did not eliminate the activity. Further work will be needed to identify the novel enzyme(s) responsible for the release of coumaric acid from grasses and to determine whether these enzymes are important factors of microbial biomass degradation. PMID:26762388

  13. Reaction pathway of the degradation of the p-hydroxybenzoic acid by sulfate radical generated by ionizing radiations

    NASA Astrophysics Data System (ADS)

    Criquet, Justine; Leitner, Nathalie Karpel Vel

    2015-01-01

    The degradation of p-hydroxybenzoic acid (HBA) in aqueous solutions by ionizing radiation was studied. The phenolic pollutant was easily removed by the electron beam irradiation, as more than 80% of the initial 100 μM introduced was degraded for a dose of 600 Gy. It was shown that the addition of persulfate, producing the sulfate radical as additional reactive species, induced a change in the reaction pathway. LC-MS analyses were performed in order to identify the different by-products formed. In the absence of persulfate, the main by-product formed was 3,4-dihydroxybenzoic acid, while in presence of persulfate, 1,4-benzoquinone was detected and the hydroxylated by-products were not present. A reaction pathway of HBA degradation by hydroxyl and sulfate radicals was proposed from the identification of the chemical structure of the different by-products detected. The influences of pH and dissolved oxygen were also studied. A high decline of HBA degradation was observed at pH 11 compared to pH 4.5, this decrease was minimized in the presence of persulfate. The dissolved oxygen concentration was found to be a limiting parameter of HBA degradation, however an excess of dissolved oxygen in solution did not improve the degradation to a large extent.

  14. Ascorbic acid and rates of cognitive decline in Alzheimer's disease.

    PubMed

    Bowman, Gene L; Dodge, Hiroko; Frei, Balz; Calabrese, Carlo; Oken, Barry S; Kaye, Jeffrey A; Quinn, Joseph F

    2009-01-01

    The brain maintains high levels of ascorbic acid (AA) despite a concentration gradient favoring diffusion from brain to peripheral tissues. Dietary antioxidants, including AA, appear to modify the risk of Alzheimer's disease (AD). The objective of this study was to test the hypothesis that neurodegeneration in AD is modified by brain levels of AA. Thirty-two patients with mild to moderate AD participated in a biomarker study involving standardized clinical assessments over one year. Cerebrospinal fluid (CSF) and serum were collected at baseline for AA and albumin content. Cognitive measures were collected at baseline and one year. CSF and plasma AA failed to predict cognitive decline independently, however, CSF: plasma AA ratio did. After adding CSF Albumin Index (an established marker of blood-brain barrier integrity) to the regression models the effect of CSF: plasma AA ratio as a predictor of cognitive decline was weakened. CSF: plasma AA ratio predicts rate of decline in AD. This relationship may indicate that the CSF: plasma AA ratio is an index of AA availability to the brain or may be an artifact of a relationship between blood-brain barrier impairment and neurodegeneration. PMID:19158425

  15. Draft Genome Sequence of Cupriavidus sp. Strain SK-3, a 4-Chlorobiphenyl- and 4-Clorobenzoic Acid-Degrading Bacterium

    PubMed Central

    Vilo, Claudia; Benedik, Michael J.; Ilori, Matthew

    2014-01-01

    We report the draft genome sequence of Cupriavidus sp. strain SK-3, which can use 4-chlorobiphenyl and 4-clorobenzoic acid as the sole carbon source for growth. The draft genome sequence allowed the study of the polychlorinated biphenyl degradation mechanism and the recharacterization of the strain SK-3 as a Cupriavidus species. PMID:24994805

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  17. Thermal properties of extruded injection-molded poly (lactic acid) and milkweed composites: degradation kinetics and enthalpic relaxation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Currently, most polymer composites utilize petroleum-based materials that are non-degradable and difficult to recycle or incur substantial cost for disposal. Green composites can be used in nondurable limited applications. In order to determine the degree of compatibility between Poly (lactic Acid...

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

    PubMed

    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

  19. Degradation of the antibiotic oxolinic acid by photocatalysis with TiO2 in suspension.

    PubMed

    Giraldo, Ana L; Peñuela, Gustavo A; Torres-Palma, Ricardo A; Pino, Nancy J; Palominos, Rodrigo A; Mansilla, Héctor D

    2010-10-01

    In the work presented here, a photocatalytic system using titanium Degussa P-25 in suspension was used to evaluate the degradation of 20mg L(-1) of antibiotic oxolinic acid (OA). The effects of catalyst load (0.2-1.5 g L(-1)) and pH (7.5-11) were evaluated and optimized using the surface response methodology and the Pareto diagram. In the range of variables studied, low pH values and 1.0 g L(-1) of TiO(2) favoured the efficiency of the process. Under optimal conditions the evolution of the substrate, chemical oxygen demand, dissolved organic carbon, toxicity and antimicrobial activity on Escherichia coli cultures were evaluated. The results indicate that, under optimal conditions, after 30 min, the TiO(2) photocatalytic system is able to eliminate both the substrate and the antimicrobial activity, and to reduce the toxicity of the solution by 60%. However, at the same time, ∼53% of both initial DOC and COD remain in solution. Thus, the photocatalytical system is able to transform the target compound into more oxidized by-products without antimicrobial activity and with a low toxicity. The study of OA by-products using liquid chromatography coupled with mass spectrometry, as well as the evaluation of OA degradation in acetonitrile media as solvent or in the presence of isopropanol and iodide suggest that the reaction is initiated by the photo-Kolbe reaction. Adsorption isotherm experiments in the dark indicated that under pH 7.5, adsorption corresponded to the Langmuir adsorption model, indicating the dependence of the reaction on an initial adsorption step. PMID:20633918

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

    PubMed

    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

  1. The effect of fluid shear stress on the in vitro degradation of poly(lactide-co-glycolide) acid membranes.

    PubMed

    Chu, Zhaowei; Zheng, Quan; Guo, Meng; Yao, Jie; Xu, Peng; Feng, Wentao; Hou, Yongzhao; Zhou, Gang; Wang, Lizhen; Li, Xiaoming; Fan, Yubo

    2016-09-01

    Poly(lactide-co-glycolide) acid (PLGA) has been widely used as a biodegradable polymer material for coating stents or fabricating biodegradable stents. Its mechanism of degradation has been extensively investigated, especially with regard to how tensile and compressive loadings may affect the in vitro degradation of PLGA. Fluid shear stress is also one of the most important factors in the development of atherosclerosis and restenosis. But the effect of fluid shear stress on the degradation process is still unclear. The purpose of this study was to characterize the in vitro degradation of PLGA membranes that experienced different fluid shear stresses in 150 mL of deionized water at 37°C for 20 days. Particular emphasis was given to changes in the viscosity of the degradation solution, as well as the mechanical and morphological properties of the samples. The viscosity of the degradation solution with the mechanical loaded specimens was more severely affected than that of the control group. Increasing the fluid shear stress could accelerate the loss of the ultimate strength of PLGA membranes while it slowed down the change of the tensile elastic modulus in the early period. With regard to morphology, the surface roughness was more obviously reduced in the loaded groups. This indicated that the fluid shear stress could affect the in vitro degradation of PLGA membranes. Therefore, this study could help improve the design of PLGA membranes for biomedical applications. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2016. PMID:27124798

  2. PHENOXYACETIC ACID DEGRADATION BY THE 2,4-DICHLOROPHENOXYACETIC ACID (TFD) PATHWAY OF PLASMID PJP4: MAPPING AND CHARACTERIZATION OF THE TFD REGULATORY GENE

    EPA Science Inventory

    Plasmid pJP4 enables Alcaligenes eutrophus JMP134 to degrade 3-chlorobenzoate and 2,4-dichlorophenoxyacetic acid (TFD), Plasmid pROl0 is a derivative of pJP4 obtained by insertion of TN1721 into a nonessential region of pJP4. lasmid pROl0l was transferred by conjugation to severa...

  3. Degradation of atrazine and 2, 4-dichlorophenoxyacetic acid by mycorrhizal fungi at three nitrogen concentrations in vitro

    SciTech Connect

    Donnelly, P.K.; Crawford, D.L. ); Entry, J.A. )

    1993-08-01

    Atrazine is a chlorinated aromatic hydrocarbon with an extremely low rated of degradation, especially in cold, dry climates. Biodegradation of the herbicide 2,4-D is known to occur in warm, moist soil, but it is dependent on environmental conditions and soil characteristics. This study examines the biodegradation of Atrazine and 2,4-D under various physiological conditions. Both mycorrhizal and nonmycorrhizal fungi were used. Phanerochaete chrysosporium was the best 2,4-D-degrading organism, but it was not able to mineralize atrazine. The ericoid mycorrhizal fungi degraded atrazine most effectively. 28 refs., 4 tabs.

  4. Cooling rate- and hydrogen content-dependent hydride reorientation and mechanical property degradation of Zr-Nb alloy claddings

    NASA Astrophysics Data System (ADS)

    Min, Su-Jeong; Kim, Myeong-Su; Kim, Kyu-Tae

    2013-10-01

    As-received, 250 ppm and 500 ppm hydrogen-charged Zr-Nb alloy cladding tubes were employed to evaluate the effects of cooling rates on the extent of radial hydride formation and mechanical property degradations using the cooling rates of 0.3, 2.0, 4.0 and 15.0 °C/min from 400 °C to room temperature under a tensile hoop stress of 150 MPa, which may simulate a long-term cladding cool-down during an interim dry storage. The hydrogen-charged claddings showed the larger fraction and the longer average length of the radial hydrides with the slower cooling rate. These effects are more dominant for the 250 ppm-H cladding tubes than for the 500 ppm-H cladding tubes. The cooling rate- and the hydrogen content-dependent radial hydride morphology may be explained by the difference in the remaining circumferential hydride fraction at 400 °C and the cooling rate-dependent hydride nucleation and growth rates. The extent of the mechanical property degradations for the hydrogen-charged cladding tubes becomes larger with the decrease of the cooling rate and for the 250 ppm-H specimens. These phenomena are well correlated with the cooling rate- and the hydrogen content-dependent radial hydride fraction and length.

  5. [Effects of particle size of zero-valent iron on the reactivity of activating persulfate and kinetics for the degradation of acid orange 7].

    PubMed

    Li, Huan-xuan; Wan, Jin-quan; Ma, Yong-wen; Huang, Ming-zhiz; Wang, Yan; Chen Yang, Mei

    2014-09-01

    This research described the heterogeneous reactions of persulfate with different particle sizes of zero-valent iron (including 1 mm-ZVI,150 μm-ZVI,50 nm-ZVI) for degradation of acid orange 7(AO7) , and studied the kinetics and intermediate products of AO7 under these systems. The results demonstrated that these three types of ZVI were efficient in promoting the degradation of AO7, the degradation efficiencies of AO7 were 43% , 97% , and 100% within 90 min respectively, in the 1 mm-ZVI,150 μm-ZVI and 50 nm- ZVI systems, respectively. With the results of kinetic fitting models, the pseudo first-order kinetics exhibited better fitting results in the 1 mm-ZVI,150 μm-ZVI systems, while the second-order kinetics exhibited better fitting results in the 50 nm-ZVI system. And the different ZVI types exhibited difference on the AO7 degradation rate constant, which ranged as 50 nm-ZVI > 150 μm-ZVI > 1 mm-ZVI. The iron corrosion products coating on the ZVI after reaction were composed of α-Fe2 O3 and some Fe3O4 in the 1 mm-ZVI system while that consisted of Fe3O4 and α-Fe2O3, FeOOH respectively, in thel50 μm-ZVI and 50 nm-ZVI systems,. Which were identified by scanning electron microscope (SEM) with energy dispersive spectrometer (EDS) and Raman spectroscopy. Some intermediate products, including 2-naphthalenol, 2-methylphenol, 4-ethyl- 3-methyl-phenol, isoindole- 1,3-dione and phthalic acid et al. were identified by GC/MS measurement. Both UV-vis absorbance spectra and GC/MS determination indicated that there was difference in degradation paths of AO7 between the three systems. PMID:25518660

  6. Degradation of naphthalene-2,6- and naphthalene-1,6-disulfonic acid by a Moraxella sp

    SciTech Connect

    Wittich, R.M.; Tast, H.G.; Knackmuss, H.J.

    1988-07-01

    A naphthalene-2,6-disulfonic acid (2,6NDS)-degrading Moraxella strain was isolated from an industrial sewage plant. This culture could also be adapted to naphthalene-1,6-disulfonic acid as growth substrate. Regioselective 1,2-dioxygenation effected desulfonation and catabolism to 5-sulfosalicylic acid (5SS), which also could be used a the sole carbon source. 5SS-grown cells exhibited high gentisate 1,2-dioxygenase activity. Neither 5SS- nor gentisate-grown cells oxidized 2,6NDS; therefore, 2,6NDS or an early metabolite must serve as an inducer of the initial catabolic enzymes(s).

  7. The effects of cutting or of stretching skeletal muscle in vitro on the rates of protein synthesis and degradation

    NASA Technical Reports Server (NTRS)

    Seider, M. J.; Kapp, R.; Chen, C.-P.; Booth, F. W.

    1980-01-01

    Skeletal muscle preparations using cut muscle fibers have often been used in studies of protein metabolism. The present paper reports an investigation of the effect of muscle cutting or stretching in vitro on the rates of protein synthesis and/or degradation. Protein synthesis and content, and ATP and phosphocreatine levels were monitored in soleus and extensor digitorum longus muscles from the rat with various extents of muscle fiber cuts and following stretching to about 120% the resting length. Rates of protein synthesis are found to be significantly lower and protein degradation higher in the cut muscles than in uncut controls, while ATP and phosphocreatine concentrations decreased. Stretched intact muscles, on the other hand, are observed to have higher concentrations of high-energy phosphates than unstretched muscles, while rates of protein degradation were not affected. Results thus demonstrate that the cutting of skeletal muscle fibers alters many aspects of muscle metabolism, and that moderate decreases in ATP concentration do not alter rates of protein concentration in intact muscles in vitro.

  8. Inhibition of endocannabinoid-degrading enzyme fatty acid amide hydrolase increases atherosclerotic plaque vulnerability in mice.

    PubMed

    Hoyer, Friedrich Felix; Khoury, Mona; Slomka, Heike; Kebschull, Moritz; Lerner, Raissa; Lutz, Beat; Schott, Hans; Lütjohann, Dieter; Wojtalla, Alexandra; Becker, Astrid; Zimmer, Andreas; Nickenig, Georg

    2014-01-01

    The role of endocannabinoids such as anandamide during atherogenesis remains largely unknown. Fatty acid amide hydrolase (FAAH) represents the key enzyme in anandamide degradation, and its inhibition is associated with subsequent higher levels of anandamide. Here, we tested whether selective inhibition of FAAH influences the progression of atherosclerosis in mice. Selective inhibition of FAAH using URB597 resulted in significantly increased plasma levels of anandamide compared to control, as assessed by mass spectrometry experiments in mice. Apolipoprotein E-deficient (ApoE(-/-)) mice were fed a high-fat, cholesterol-rich diet to induce atherosclerotic conditions. Simultaneously, mice received either the pharmacological FAAH inhibitor URB597 1mg/kg body weight (n=28) or vehicle (n=25) via intraperitoneal injection three times a week. After eight weeks, mice were sacrificed, and experiments were performed. Vascular superoxide generation did not differ between both groups, as measured by L012 assay. To determine whether selective inhibition of FAAH affects atherosclerotic plaque inflammation, immunohistochemical staining of the aortic root was performed. Atherosclerotic plaque formation, vascular macrophage accumulation, as well as vascular T cell infiltration did not differ between both groups. Interestingly, neutrophil cell accumulation was significantly increased in mice receiving URB597 compared to control. Vascular collagen structures in atherosclerotic plaques were significantly diminished in mice treated with URB597 compared to control, as assessed by picro-sirius-red staining. This was accompanied by an increased aortic expression of matrix metalloproteinase-9, as determined by quantitative RT-PCR and western blot analysis. Inhibition of fatty acid amide hydrolase does not influence plaque size but increases plaque vulnerability in mice. PMID:24286707

  9. Metallo-hydrazone complexes immobilized in zeolite Y: Synthesis, identification and acid violet-1 degradation

    NASA Astrophysics Data System (ADS)

    Ahmed, Ayman H.; Thabet, M. S.

    2011-12-01

    Copper(II), cobalt(II) and nickel(II) complexes of hydrazone ligand (SAPH) derived from salicylaldehyde and phenylhydrazine have been encapsulated in zeolite-Y super cages via ship-in-a-bottle synthesis. Detailed characterization of the intrazeolitic complexes were performed by elemental analysis, spectral (FT-IR, UV-Vis.) studies, magnetic measurements and X-ray diffraction. Furthers, surface texture and thermal analysis (TG, DTG, DTA) have provided further evidence for successful immobilization of the metal complexes inside zeolite Y. Investigation of the stereochemistry of these incorporated chelates pointed out that, SAPH ligand is capable to coordinate with the central metal through the (C dbnd N), phenolic (OH) and (NH) groups forming polynuclear structures. The involvement of zeolite oxygen in coordination was postulated in the hybrid materials. The intrazeolitic copper, cobalt and nickel-SAPH complexes have distorted tetrahedral, octahedral and square-pyramidal configurations, respectively. The zeolite encapsulated complexes are thermally stable up to 800 °C except Cu(II) sample which is thermally stable up to midpoint 428 °C. The assessment of the catalytic activity was performed by the use of the photo-degradation of acid violet-1 dye as a probe reaction in presence of H 2O 2 as an oxidant. Decolorization of acid violet-1 dye was examined under the same conditions whereas the unpromoted zeolite and Cu II, Co II, Ni II-hydrazone complexes supported on zeolite showed 13% and 76%, 53%, 43% color removal, respectively. The results revealed that, the zeolite encapsulated Cu(II) complex generally exhibited better catalytic efficiency (76%) compared with other investigated zeolite encapsulated metal-hydrazone samples.

  10. Are Phragmites australis enzymes involved in the degradation of the textile azo dye acid orange 7?

    PubMed

    Carias, Cátia C; Novais, Júlio M; Martins-Dias, Susete

    2008-01-01

    The role of antioxidant and detoxification enzymes of Phragmites australis, in the degradation of an azo dye, acid orange 7 (AO7), was studied. Activities of several enzymes involved in plant protection against stress were assayed through the activity characterization of superoxide dismutase (SOD), peroxidases (POD), catalase (CAT), ascorbate peroxidase (APOX), dehydroascorbate reductase (DHAR) and glutathione S-transferase (GST), obtained from P. australis crude extracts of leaves, stems and roots. A sub-surface vertical flow constructed wetland, planted with P. australis was used to test the plants response to the AO7 exposure at two different concentrations (130 and 700 mg l(-1)). An activity increase was detected for an AO7 concentration of 130 mg l(-1) for most enzymes studied (SOD, CAT and APOX), especially in leaves, suggesting a response of the reactive oxygen species scavenging enzymes to the chemical stress imposed. GST activity increase in this situation can also be interpreted as an activation of the detoxification pathway and subsequent AO7 conjugation. A totally different behaviour was observed for AO7 at 700 mg l(-1). An evident decrease in activity was observed for SOD, CAT, APOX and GST, probably due to enzymatic inhibition by AO7. Contrarily, DHAR activity augmented drastically in this situation. POD activity was not greatly affected during trial. Altogether these results suggest that P. australis effectively uses the ascorbate-glutathione pathway for the detoxification of AO7. PMID:17336060

  11. Neuraminidase-Dependent Degradation of Polysialic Acid Is Required for the Lamination of Newly Generated Neurons

    PubMed Central

    Sajo, Mari; Sugiyama, Hiroki; Yamamoto, Hideaki; Tanii, Takashi; Matsuki, Norio; Ikegaya, Yuji; Koyama, Ryuta

    2016-01-01

    Hippocampal granule cells (GCs) are generated throughout the lifetime and are properly incorporated into the innermost region of the granule cell layer (GCL). Hypotheses for the well-regulated lamination of newly generated GCs suggest that polysialic acid (PSA) is present on the GC surface to modulate GC-to-GC interactions, regulating the process of GC migration; however, direct evidence of this involvement is lacking. We show that PSA facilitates the migration of newly generated GCs and that the activity of N-acetyl-α-neuraminidase 1 (NEU1, sialidase 1) cleaves PSA from immature GCs, terminating their migration in the innermost GCL. Developing a migration assay of immature GCs in vitro, we found that the pharmacological depletion of PSA prevents the migration of GCs, whereas the inhibition of PSA degradation with a neuraminidase inhibitor accelerates this migration. We found that NEU1 is highly expressed in immature GCs. The knockdown of NEU1 in newly generated GCs in vivo increased PSA presence on these cells, and attenuated the proper termination of GC migration in the innermost GCL. In conclusion, this study identifies a novel mechanism that underlies the proper lamination of newly generated GCs through the modulation of PSA presence by neuronal NEU1. PMID:26731280

  12. Uric Acid-Degrading Bacteria in Guts of Termites [Reticulitermes flavipes (Kollar)] †

    PubMed Central

    Potrikus, C. J.; Breznak, John A.

    1980-01-01

    Uricolytic bacteria were present in guts of Reticulitermes flavipes in populations up to 6 × 104 cells per gut. Of 82 strains isolated under strict anaerobic conditions, most were group N Streptococcus sp., Bacteroides termitidis, and Citrobacter sp. All isolates used uric acid (UA) as an energy source anaerobically, but not aerobically, and NH3 was the major nitrogenous product of uricolysis. However, none of the isolates had an absolute requirement for UA. Utilization of heterocyclic compounds other than UA was limited. Fresh termite gut contents also degraded UA anaerobically, as measured by 14CO2 evolution from [2-14C]UA. The magnitude of anaerobic uricolysis [0.67 pmol of UA catabolized/(gut × h)] was entirely consistent with the population density of uricolytic bacteria in situ. Uricolytic gut bacteria may convert UA in situ to products usable by termites for carbon, nitrogen, energy, or all three. This possibility is consistent with the fact that R. flavipes termites from UA, but they do not void the purine in excreta despite the lack of uricase in their tissues. PMID:16345587

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

    PubMed

    Chang, Feng-chih; Simcik, Matt F; Capel, Paul D

    2011-03-01

    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 <0.01 to 9.1 ng/m(3) and from <0.1 to 2.5 µg/L in air and rain samples, respectively. The frequency of detection and median and maximum concentrations of 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. PMID:21128261

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

    USGS Publications Warehouse

    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 <0.1 to 2.5 µg/L in air and rain samples, respectively. The frequency of detection and median and maximum concentrations of 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.

  15. Low Phytic Acid Barley Responses to Phosphorus Rates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Low phytic acid (LPA) barley (Hordeum vulgare L.) cultivars partition phosphorus in seed tissue differently than conventional barley cultivars through a reduction in seed phytic acid (myo-inositol-1,2,3,4,5,6-hexkisphosphate) coupled with an increase in inorganic phosphorus. The response of the LPA...

  16. Developing an in vitro method for determining feed soluble protein degradation rate by mixed ruminal microorganisms

    Technology Transfer Automated Retrieval System (TEKTRAN)

    For the purposes of ration balancing using predictive computer models, more accurate content and rumen soluble protein degradability values are needed, especially for highly processed feeds. Consequently, a standardized method of determination is needed. Hence, a novel ruminal in vitro method is d...

  17. Separation and detection of VX and its methylphosphonic acid degradation products on a microchip using indirect laser-induced fluorescence.

    PubMed

    Heleg-Shabtai, Vered; Gratziany, Natzach; Liron, Zvi

    2006-05-01

    The application of indirect LIF (IDLIF) technique for on-chip electrophoretic separation and detection of the nerve agent O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothiolate (VX) and its major phosphonic degradation products, ethyl methylphosphonic acid (EMPA) and methylphosphonic acid (MPA) was demonstrated. Separation and detection of MPA degradation products of VX and the nerve agent isopropyl methylphosphonofluoridate (GB) are presented. The negatively charged dye eosin was found to be a good fluorescent marker for both the negatively charged phosphonic acids and the positively charged VX, and was chosen as the IDLIF visualization fluorescent dye. Separation and detection of VX, EMPA, and MPA in a simple-cross microchip were completed within less than a minute, and consumed only a 50 pL sample volume. A characteristic system peak that appeared in all IDLIF electropherograms served as an internal standard that increased the reliability of peak identification. The negative peak of both VX and the MPAs is in agreement with indirect detection theory and with previous reports in the literature. The LOD of VX and EMPA by IDLIF was 30 and 37 microM, respectively. Despite the fact that the detection sensitivity is relatively low, the rapid simultaneous on-chip analysis of both VX and its degradation products as well as the separation and detection of the MPA degradation products of both VX and GB, increases detection reliability and may present a choice when sensitivity is not critical compared with speed and simplicity of the assay. PMID:16703628

  18. Structural Insights into 2,2′-Azino-Bis(3-Ethylbenzothiazoline-6-Sulfonic Acid) (ABTS)-Mediated Degradation of Reactive Blue 21 by Engineered Cyathus bulleri Laccase and Characterization of Degradation Products

    PubMed Central

    Kenzom, T.; Srivastava, P.

    2014-01-01

    Advanced oxidation processes are currently used for the treatment of different reactive dyes which involve use of toxic catalysts. Peroxidases are reported to be effective on such dyes and require hydrogen peroxide and/or metal ions. Cyathus bulleri laccase, expressed in Pichia pastoris, catalyzes efficient degradation (78 to 85%) of reactive azo dyes (reactive black 5, reactive orange 16, and reactive red 198) in the presence of synthetic mediator ABTS [2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)]. This laccase was engineered to degrade effectively reactive blue 21 (RB21), a phthalocyanine dye reported to be decolorized only by peroxidases. The 816-bp segment (toward the C terminus) of the lcc gene was subjected to random mutagenesis and enzyme variants (Lcc35, Lcc61, and Lcc62) were selected based on increased ABTS oxidizing ability. Around 78 to 95% decolorization of RB21 was observed with the ABTS-supplemented Lcc variants in 30 min. Analysis of the degradation products by mass spectrometry indicated the formation of several low-molecular-weight compounds. Mapping the mutations on the modeled structure implicated residues both near and far from the T1 Cu site that affected the catalytic efficiency of the mutant enzymes on ABTS and, in turn, the rate of oxidation of RB21. Several inactive clones were also mapped. The importance of geometry as well as electronic changes on the reactivity of laccases was indicated. PMID:25261507

  19. Analysis and detection of the herbicides dimethenamid and flufenacet and their sulfonic and oxanilic acid degradates in natural water

    USGS Publications Warehouse

    Zimmerman, L.R.; Schneider, R.J.; Thurman, E.M.

    2002-01-01

    Dimethenamid [2-chloro-N-(2,4-dimethyl-3-thienyl)-N-(2-methoxy-1-methylethyl)acetamide] and flufenacet [N-(4-fluorophenyl)-N-(1-methylethyl)-2-(5-(trifluoromethyl)-1,3,4- thiadiazol-2-yl)oxy] were isolated by C-18 solid-phase extraction and separated from their ethanesulfonic acid (ESA) and oxanilic acid (OXA) degradates during their elution using ethyl acetate for the parent compound, followed by methanol for the polar degradates. The parent compounds were detected using gas chromatography-mass spectrometry in selected-ion mode. The ESA and OXA degradates were detected using high-performance liquid chromatography-electrospray mass spectrometry (HPLC-ESPMS) in negative-ion mode. The method detection limits for a 123-mL sample ranged from 0.01 to 0.07 ??g/L. These methods are compatible with existing methods and thus allow for analysis of 17 commonly used herbicides and 18 of their degradation compounds with one extraction. In a study of herbicide transport near the mouth of the Mississippi River during 1999 and 2000, dimethenamid and its ESA and OXA degradates were detected in surface water samples during the annual spring flushes. For flufenacet, the only detections at the study site were for the ESA degradates in samples collected at the peak of the herbicide spring flush in 2000. The low frequency of detections in surface water likely is due to dimethenamid and flufenacet being relatively new herbicides. In addition, detectable amounts of the stable degradates have not been detected in ground water.

  20. Microbial degradation and humification of the lawn care pesticide 2,4-dichlorophenoxyacetic acid during the composting of yard trimmings.

    PubMed Central

    Michel, F C; Reddy, C A; Forney, L J

    1995-01-01

    The fate of the widely used lawn care herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) during the composting of yard trimmings consisting of primarily leaves and grass is an important unexplored question. In this study, we determined the extent of 2,4-D mineralization, incorporation into humic matter, volatilization, and sorption during the composting of yard trimmings. Yard trimmings (2:1 [wt/wt] leaves-grass) were amended with 14C-ring-labeled 2,4-D (17 mg/kg of dry weight) and composted in a temperature-controlled laboratory scale compost system. During composting, thermophilic microbes were numerically dominant, reaching a maximum of 2 x 10(11)/g. At the end of composting, 46% of the organic matter (OM) present in the yard trimmings was lost and the compost was stable, with an oxygen uptake rate of 0.09 mg of O2 per g of OM per h, and was well humified (humification index, 0.39). Mineralization of the OM temporally paralleled mineralization of 2,4-D. In the final compost, 47% of the added 2,4-D carbon was mineralized, about 23% was complexed with high-molecular-weight humic acids, and about 20% was not extractable (humin fraction). Less than 1% of the added 14C was present in water expressed from the finished compost, suggesting a low potential for leaching of 2,4-D. Very little volatilization of 2,4-D occurred during composting. It is of interest that our results indicate active mineralization of 2,4-D at composting temperatures of 60 degrees C because microbial 2,4-D degradation at thermophilic temperatures has not been previously documented. PMID:7618868

  1. Radiation-induced failures and degradation of wireless real-time dosimeter under high-dose-rate irradiation

    NASA Astrophysics Data System (ADS)

    Tsuchiya, K.; Kuroki, K.; Akiba, N.; Kurosawa, K.; Matsumoto, T.; Nishiyama, J.; Harano, H.

    2010-04-01

    Radiation-induced malfunction and degradation of electronic modules in certain operating conditions are described in this report. The cumulative radiation effects on Atmel AVR microcontrollers, and 2.4 GHz and 303 MHz wireless network devices were evaluated under gamma ray irradiation with dose rates of 100, 10 and 3 Gy/h. The radiation-induced malfunctions occurred at doses of 510+/-22 Gy for AVR microcontrollers, and 484+/-111 and 429+/-14 Gy for 2.4 GHz and 303 MHz wireless network devices, respectively, under a 100 Gy/h equivalent dose rate. The degradation of microcontrollers occurred for total ionizing doses between 400 and 600 Gy under X-ray irradiation. In addition, we evaluated the reliability of neutron dosimeters using a standard neutron field. One of the neutron dosimeters gave a reading that was half of the standard field value.

  2. Chemical sporulation and germination: cytoprotective nanocoating of individual mammalian cells with a degradable tannic acid-FeIII complex.

    PubMed

    Lee, Juno; Cho, Hyeoncheol; Choi, Jinsu; Kim, Doyeon; Hong, Daewha; Park, Ji Hun; Yang, Sung Ho; Choi, Insung S

    2015-12-01

    Individual mammalian cells were coated with cytoprotective and degradable films by cytocompatible processes maintaining the cell viability. Three types of mammalian cells (HeLa, NIH 3T3, and Jurkat cells) were coated with a metal-organic complex of tannic acid (TA) and ferric ion, and the TA-Fe(III) nanocoat effectively protected the coated mammalian cells against UV-C irradiation and a toxic compound. More importantly, the cell proliferation was controlled by programmed formation and degradation of the TA-Fe(III) nanocoat, mimicking the sporulation and germination processes found in nature. PMID:26528931

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

    PubMed Central

    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-), which was previously derived from A. eutrophus JMP134 by curing of the 2,4-D-degradative plasmid pJP4, and JMP228 carrying pBH501aE (a plasmid derived from pJP4 by deletion of a large part of the tfdA gene which encodes the first step in the mineralization of 2,4-D). By using agricultural soil that had been treated with 2,4-D for several years, transconjugants were obtained with both recipients. However, when untreated control soil was used, no transconjugants were isolated. The various transconjugants had plasmids with seven different EcoRI restriction patterns. The corresponding plasmids are designated pEMT1 to pEMT7. Unlike pJP4, pEMT1 appeared not to be an IncP1 plasmid, but all the others (pEMT2 to pEMT7) belong to the IncP1 group. Hybridization with individual probes for the tfdA to tfdF genes of pJP4 demonstrated that all plasmids showed high degrees of homology to the tfdA gene. Only pEMT1 showed a high degree of homology to tfdB, tfdC, tfdD, tfdE, and tfdF, while the others showed only moderate degrees of homology to tfdB and low degrees of homology to tfdC.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7646006

  4. Novel 2,4-Dichlorophenoxyacetic Acid Degradation Genes from Oligotrophic Bradyrhizobium sp. Strain HW13 Isolated from a Pristine Environment

    PubMed Central

    Kitagawa, Wataru; Takami, Sachiko; Miyauchi, Keisuke; Masai, Eiji; Kamagata, Yoichi; Tiedje, James M.; Fukuda, Masao

    2002-01-01

    The tfd genes of Ralstonia eutropha JMP134 are the only well-characterized set of genes responsible for 2,4-dichlorophenoxyacetic acid (2,4-D) degradation among 2,4-D-degrading bacteria. A new family of 2,4-D degradation genes, cadRABKC, was cloned and characterized from Bradyrhizobium sp. strain HW13, a strain that was isolated from a buried Hawaiian soil that has never experienced anthropogenic chemicals. The cadR gene was inferred to encode an AraC/XylS type of transcriptional regulator from its deduced amino acid sequence. The cadABC genes were predicted to encode 2,4-D oxygenase subunits from their deduced amino acid sequences that showed 46, 44, and 37% identities with the TftA and TftB subunits of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) oxygenase of Burkholderia cepacia AC1100 and with a putative ferredoxin, ThcC, of Rhodococcus erythropolis NI86/21, respectively. They are thoroughly different from the 2,4-D dioxygenase gene, tfdA, of R. eutropha JMP134. The cadK gene was presumed to encode a 2,4-D transport protein from its deduced amino acid sequence that showed 60% identity with the 2,4-D transporter, TfdK, of strain JMP134. Sinorhizobium meliloti Rm1021 cells containing cadRABKC transformed several phenoxyacetic acids, including 2,4-D and 2,4,5-T, to corresponding phenol derivatives. Frameshift mutations indicated that each of the cadRABC genes was essential for 2,4-D conversion in strain Rm1021 but that cadK was not. Five 2,4-D degraders, including Bradyrhizobium and Sphingomonas strains, were found to have cadA gene homologs, suggesting that these 2,4-D degraders share 2,4-D degradation genes similar to those of strain HW13 cadABC. PMID:11751829

  5. Novel Pathway for the Degradation of 2-Chloro-4-Nitrobenzoic Acid by Acinetobacter sp. Strain RKJ12▿†

    PubMed Central

    Prakash, Dhan; Kumar, Ravi; Jain, R. K.; Tiwary, B. N.

    2011-01-01

    The organism Acinetobacter sp. RKJ12 is capable of utilizing 2-chloro-4-nitrobenzoic acid (2C4NBA) as a sole source of carbon, nitrogen, and energy. In the degradation of 2C4NBA by strain RKJ12, various metabolites were isolated and identified by a combination of chromatographic, spectroscopic, and enzymatic activities, revealing a novel assimilation pathway involving both oxidative and reductive catabolic mechanisms. The metabolism of 2C4NBA was initiated by oxidative ortho dehalogenation, leading to the formation of 2-hydroxy-4-nitrobenzoic acid (2H4NBA), which subsequently was metabolized into 2,4-dihydroxybenzoic acid (2,4-DHBA) by a mono-oxygenase with the concomitant release of chloride and nitrite ions. Stoichiometric analysis indicated the consumption of 1 mol O2 per conversion of 2C4NBA to 2,4-DHBA, ruling out the possibility of two oxidative reactions. Experiments with labeled H218O and 18O2 indicated the involvement of mono-oxygenase-catalyzed initial hydrolytic dechlorination and oxidative denitration mechanisms. The further degradation of 2,4-DHBA then proceeds via reductive dehydroxylation involving the formation of salicylic acid. In the lower pathway, the organism transformed salicylic acid into catechol, which was mineralized by the ortho ring cleavage catechol-1,2-dioxygenase to cis, cis-muconic acid, ultimately forming tricarboxylic acid cycle intermediates. Furthermore, the studies carried out on a 2C4NBA− derivative and a 2C4NBA+ transconjugant demonstrated that the catabolic genes for the 2C4NBA degradation pathway possibly reside on the ∼55-kb transmissible plasmid present in RKJ12. PMID:21803909

  6. Degradation State, Sources, and Reactivity of Dissolved Organic Matter from an Amino Acid Time Series in an Agricultural Watershed

    NASA Astrophysics Data System (ADS)

    Matiasek, S. J.; Pellerin, B. A.; Spencer, R. G.; Bergamaschi, B. A.; Hernes, P.

    2015-12-01

    A detailed time series of dissolved amino acids was obtained in an agricultural watershed in the northern Central Valley, California, USA to investigate the roles of hydrologic and seasonal changes on the composition of dissolved organic matter (DOM). Total hydrolysable amino acid (THAA) concentrations ranged from 0.55 to 9.96 μM (mean 3.76 ± 1.80 μM) and not only peaked with discharge during winter storms, but also remained elevated throughout the irrigation season when discharge was low. Summer irrigation was a critical hydrologic regime for DOM cycling, since it mobilized DOM similar in concentration and reactivity to DOM released during winter storms for an extended period of time, with the largest amino acid contributions to the dissolved organic carbon (DOC) and the dissolved organic nitrogen (DON) pools (3.4 ‒ 3.7 % DOC-AA, 17.4 ‒ 22.5 % DON-AA), the largest proportion of basic amino acids (B/(B+A) = 0.19 ‒ 0.22), and the largest degradation index values (mean 1.37 ± 0.96). The mole percent of non-protein amino acids, commonly considered as an indicator of microbial degradation, decreased with DOM processing and was highest during summer (mean 4.1 ± 1.1%). A lack of correlation between THAA concentrations and UV-Vis absorbance and fluorescence proxies (including "protein-like" fluorophores B and T) indicated that optical properties may be limited in representing amino acid dynamics in this system. A new parameter for DOM processing derived from trends in individual amino acids demonstrated strong potential for inferring the extent of DOM degradation in freshwater systems. The biogeochemical relevance of irrigation practices is heightened by timing, since the additional export of reactive DOM coincides with enhanced downstream DOM processing in the Sacramento-San Joaquin River Delta, a critical habitat for endangered species serving as water source for 25 million Californians.

  7. The effect of microbubbles on gas-liquid mass transfer coefficient and degradation rate of COD in wastewater treatment.

    PubMed

    Yao, Kangning; Chi, Yong; Wang, Fei; Yan, Jianhua; Ni, Mingjiang; Cen, Kefa

    2016-01-01

    A commonly used aeration device at present has the disadvantages of low mass transfer rate because the generated bubbles are several millimeters in diameter which are much bigger than microbubbles. Therefore, the effect of a microbubble on gas-liquid mass transfer and wastewater treatment process was investigated. To evaluate the effect of each bubble type, the volumetric mass transfer coefficients for microbubbles and conventional bubbles were determined. The volumetric mass transfer coefficient was 0.02905 s(-1) and 0.02191 s(-1) at a gas flow rate of 0.67 L min(-1) in tap water for microbubbles and conventional bubbles, respectively. The degradation rate of simulated municipal wastewater was also investigated, using aerobic activated sludge and ozone. Compared with the conventional bubble generator, the chemical oxygen demand (COD) removal rate was 2.04, 5.9, 3.26 times higher than those of the conventional bubble contactor at the same initial COD concentration of COD 200 mg L(-1), 400 mg L(-1), and 600 mg L(-1), while aerobic activated sludge was used. For the ozonation process, the rate of COD removal using microbubble generator was 2.38, 2.51, 2.89 times of those of the conventional bubble generator. Based on the results, the effect of initial COD concentration on the specific COD degradation rate were discussed in different systems. Thus, the results revealed that microbubbles could enhance mass transfer in wastewater treatment and be an effective method to improve the degradation of wastewater. PMID:27120652

  8. Acidic Nanoparticles Are Trafficked to Lysosomes and Restore an Acidic Lysosomal pH and Degradative Function to Compromised ARPE-19 Cells

    PubMed Central

    Baltazar, Gabriel C.; Guha, Sonia; Lu, Wennan; Lim, Jason; Boesze-Battaglia, Kathleen; Laties, Alan M.; Tyagi, Puneet; Kompella, Uday B.; Mitchell, Claire H.

    2012-01-01

    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. PMID:23272048

  9. Silicate, borosilicate, and borate bioactive glass scaffolds with controllable degradation rate for bone tissue engineering applications. I. Preparation and in vitro degradation.

    PubMed

    Fu, Qiang; Rahaman, Mohamed N; Fu, Hailuo; Liu, Xin

    2010-10-01

    Bioactive glass scaffolds with a microstructure similar to that of dry human trabecular bone but with three different compositions were evaluated for potential applications in bone repair. The preparation of the scaffolds and the effect of the glass composition on the degradation and conversion of the scaffolds to a hydroxyapatite (HA)-type material in a simulated body fluid (SBF) are reported here (Part I). The in vitro response of osteogenic cells to the scaffolds and the in vivo evaluation of the scaffolds in a rat subcutaneous implantation model are described in Part II. Scaffolds (porosity = 78-82%; pore size = 100-500 microm) were prepared using a polymer foam replication technique. The glasses consisted of a silicate (13-93) composition, a borosilicate composition (designated 13-93B1), and a borate composition (13-93B3), in which one-third or all of the SiO2 content of 13-93 was replaced by B2O3, respectively. The conversion rate of the scaffolds to HA in the SBF increased markedly with the B2O3 content of the glass. Concurrently, the pH of the SBF also increased with the B2O3 content of the scaffolds. The compressive strengths of the as-prepared scaffolds (5-11 MPa) were in the upper range of values reported for trabecular bone, but they decreased markedly with immersion time in the SBF and with increasing B2O3 content of the glass. The results show that scaffolds with a wide range of bioactivity and degradation rate can be achieved by replacing varying amounts of SiO(2) in silicate bioactive glass with B2O3. PMID:20544804

  10. Bacterial inoculants of forage grasses that enhance degradation of 2-chlorobenzoic acid in soil

    SciTech Connect

    Siciliano, S.D.; Germida, J.J.

    1997-06-01

    Biological remediation of contaminated soil is an effective method of reducing risk to human and ecosystem health. Bacteria and plants might be used to enhance remediation of soil pollutants in situ. This study assessed the potential of bacteria, plants, and plant-bacteria associations to remediate 2-chlorobenzoic acid (2CBA) contaminated soil. Initially, grass viability was assessed in 2CBA-contaminated soil. Soil was contaminated with 2CBA, forage grasses were grown under growth chamber conditions for 42 or 60 d, and the 2CBA concentration in soil was determined by gas chromatography. Only five of 16 forage grasses grew in 2CBA-treated soil. Growth of Bromus inermis had no effect on 2CBA concentration, whereas Agropyron intermedium, B. biebersteinii, A. riparum, and Elymus dauricus decreased 2CBA relative to nonplanted control soil by 32 to 42%. The 12 bacteria isolates were screened for their ability to promote the germination of the five grasses in 2CBA-contaminated soil. Inoculation of A. riparum with Pseudomonas aeruginosa strain R75, a proven plant growth-promoting rhizobacterium, increased seed germination by 80% and disappearance of 2CBA by 20% relative to noninoculated plants. Inoculation of E. dauricus with a mixture of P. savastanoi strain CB35, a 2CBA-degrading bacterium, and P. aeruginosa strain R75 increased disappearance of 2CBA by 112% relative to noninoculated plants. No clear relationship between enhanced 2CBA disappearance and increased plant biomass was found. These results suggest that specific plant-microbial systems can be developed to enhance remediation of pollutants in soil.

  11. Complete degradation of the azo dye Acid Orange-7 and bioelectricity generation in an integrated microbial fuel cell, aerobic two-stage bioreactor system in continuous flow mode at ambient temperature.

    PubMed

    Fernando, Eustace; Keshavarz, Taj; Kyazze, Godfrey

    2014-03-01

    In this study, the commercially used model azo dye Acid Orange-7 (AO-7) was fully degraded into less toxic intermediates using an integrated microbial fuel cell (MFC) and aerobic bioreactor system. The integrated bioreactor system was operated at ambient temperature and continuous-flow mode. AO-7 loading rate was varied during experiments from 70gm(-3)day(-1) to 210gm(-3)day(-1). Colour and soluble COD removal rates reached>90% under all AO-7 loading rates. The MFC treatment stage prompted AO-7 to undergo reductive degradation into its constituent aromatic amines. HPLC-MS analysis of metabolite extracts from the aerobic stage of the bioreactor system indicated further oxidative degradation of the resulting aromatic amines into simpler compounds. Bioluminescence based Vibrio fischeri ecotoxicity testing demonstrated that aerobic stage effluent exhibited toxicity reductions of approximately fivefold and ten-fold respectively compared to the dye wastewater influent and MFC-stage effluent. PMID:24495541

  12. Chemical sporulation and germination: cytoprotective nanocoating of individual mammalian cells with a degradable tannic acid-FeIII complex

    NASA Astrophysics Data System (ADS)

    Lee, Juno; Cho, Hyeoncheol; Choi, Jinsu; Kim, Doyeon; Hong, Daewha; Park, Ji Hun; Yang, Sung Ho; Choi, Insung S.

    2015-11-01

    Individual mammalian cells were coated with cytoprotective and degradable films by cytocompatible processes maintaining the cell viability. Three types of mammalian cells (HeLa, NIH 3T3, and Jurkat cells) were coated with a metal-organic complex of tannic acid (TA) and ferric ion, and the TA-FeIII nanocoat effectively protected the coated mammalian cells against UV-C irradiation and a toxic compound. More importantly, the cell proliferation was controlled by programmed formation and degradation of the TA-FeIII nanocoat, mimicking the sporulation and germination processes found in nature.Individual mammalian cells were coated with cytoprotective and degradable films by cytocompatible processes maintaining the cell viability. Three types of mammalian cells (HeLa, NIH 3T3, and Jurkat cells) were coated with a metal-organic complex of tannic acid (TA) and ferric ion, and the TA-FeIII nanocoat effectively protected the coated mammalian cells against UV-C irradiation and a toxic compound. More importantly, the cell proliferation was controlled by programmed formation and degradation of the TA-FeIII nanocoat, mimicking the sporulation and germination processes found in nature. Electronic supplementary information (ESI) available: Experimental details, LSCM images, and SEM and TEM images. See DOI: 10.1039/c5nr05573c

  13. Purex diluent degradation

    SciTech Connect

    Tallent, O.K.; Mailen, J.C.; Pannell, K.D.

    1984-02-01

    The chemical degradation of normal paraffin hydrocarbon (NPH) diluents both in the pure state and mixed with 30% tributyl phosphate (TBP) was investigated in a series of experiments. The results show that degradation of NPH in the TBP-NPH-HNO/sub 3/ system is consistent with the active chemical agent being a radical-like nitrogen dioxide (NO/sub 2/) molecule, not HNO/sub 3/ as such. Spectrophotometric, gas chromatographic, mass spectrographic, and titrimetric methods were used to identify the degradation products, which included alkane nitro and nitrate compounds, alcohols, unsaturated alcohols, nitro alcohols, nitro alkenes, ketones, and carboxylic acids. The degradation rate was found to increase with increases in the HNO/sub 3/ concentration and the temperature. The rate was decreased by argon sparging to remove NO/sub 2/ and by the addition of butanol, which probably acts as a NO/sub 2/ scavenger. 13 references, 11 figures.

  14. Effect of Glucose on the Fatty Acid Composition of Cupriavidus necator JMP134 during 2,4-Dichlorophenoxyacetic Acid Degradation: Implications for Lipid-Based Stable Isotope Probing Methods▿†

    PubMed Central

    Lerch, Thomas Z.; Dignac, Marie-France; Barriuso, Enrique; Mariotti, André

    2011-01-01

    Combining lipid biomarker profiling with stable isotope probing (SIP) is a powerful technique for studying specific microbial populations responsible for the degradation of organic pollutants in various natural environments. However, the presence of other easily degradable substrates may induce significant physiological changes by altering both the rate of incorporation of the target compound into the biomass and the microbial lipid profiles. In order to test this hypothesis, Cupriavidus necator JMP134, a 2,4-dichlorophenoxyacetic acid (2,4-D)-degrading bacterium, was incubated with [13C]2,4-D, [13C]glucose, or mixtures of both substrates alternatively labeled with 13C. C. necator JMP134 exhibited a preferential use of 2,4-D over glucose. The isotopic analysis showed that glucose had only a small effect on the incorporation of the acetic chain of 2,4-D into the biomass (at days 2 and 3) and no effect on that of the benzenic ring. The addition of glucose did change the fatty acid methyl ester (FAME) composition. However, the overall FAME isotopic signature reflected that of the entire biomass. Compound-specific individual isotopic analyses of FAME composition showed that the 13C-enriched FAME profiles were slightly or not affected when tracing the 2,4-D acetic chain or 2,4-D benzenic ring, respectively. This batch study is a necessary step for validating the use of lipid-based SIP methods in complex environments. PMID:21856833

  15. Identification of a novel enzymatic activity from lactic acid bacteria able to degrade biogenic amines in wine.

    PubMed

    Callejón, S; Sendra, R; Ferrer, S; Pardo, I

    2014-01-01

    The main objectives of this study were the search for enzymatic activities responsible for biogenic amine (BA) degradation in lactic acid bacteria (LAB) strains isolated from wine, their identification, and the evaluation of their applicability for reducing BAs in wine. Fifty-three percent of the 76 LAB cell extracts showed activity against a mixture of histamine, tyramine, and putrescine when analyzed in-gel. The quantification of the degrading ability for each individual amine was tested in a synthetic medium and wine. Most of the bacteria analyzed were able to degrade the three amines in both conditions. The highest percentages of degradation in wine were those of putrescine: up to 41% diminution in 1 week. Enzymes responsible for amine degradation were isolated and purified from Lactobacillus plantarum J16 and Pediococcus acidilactici CECT 5930 strains and were identified as multicopper oxidases. This is the first report of an efficient BA reduction in wine by LAB. Furthermore, the identity of the enzymes involved has been revealed. PMID:23515835

  16. Promoted degradation of perfluorooctanic acid by persulfate when adding activated carbon.

    PubMed

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

    2013-10-15

    Treatment of persistent perfluorooctanoic acid (PFOA) in water using persulfate (PS) oxidation typically requires an elevated temperature or UV irradiation, which is energy-consuming. Under relatively low temperatures of 25-45°C, activated carbon (AC) activated PS oxidation of PFOA was evaluated for its potential of practical applications. With presence of AC in PS oxidation, PFOA removal efficiency at 25°C reached 682% with a high defluorination efficiency of 549% after 12h and few intermediates of short-chain perfluorinated carboxylic acids (PFCAs) were found. The removal and defluorination rates with the combined AC/PS system were approximately 12 and 19 times higher than those of the PS-only system, respectively. Activated carbon not only removes PFOA through adsorption, but also activates PS to form sulfate radicals that accelerate the decomposition and mineralization of PFOA. The activation energy for PS oxidation of PFOA was reduced from 668 to 261kJ/mol by the catalytic effect of AC, which implies a lower reaction temperature and a shorter reaction time would suffice. A 2-cycle schematic reaction mechanism was used to describe PS oxidation of PFOA with the generation of various intermediates and end-products. PMID:23978721

  17. TREATOGENIC ACTIVITY OF TRICHOLORACETIC ACID IN THE RATE

    EPA Science Inventory

    Trichloroacetic acid (TCA) is a by-product of the chlorine disinfection of water containing natural organic material. t is detectable in finished drinking water at levels comparable to the trihalomethanes (930-160 ug/L). CA is also formed in vivo after ingestion of hypochelorite ...

  18. Crystal Structure and Substrate Recognition of Cellobionic Acid Phosphorylase, Which Plays a Key Role in Oxidative Cellulose Degradation by Microbes*

    PubMed Central

    Nam, Young-Woo; Nihira, Takanori; Arakawa, Takatoshi; Saito, Yuka; Kitaoka, Motomitsu; Nakai, Hiroyuki; Fushinobu, Shinya

    2015-01-01

    The microbial oxidative cellulose degradation system is attracting significant research attention after the recent discovery of lytic polysaccharide mono-oxygenases. A primary product of the oxidative and hydrolytic cellulose degradation system is cellobionic acid (CbA), the aldonic acid form of cellobiose. We previously demonstrated that the intracellular enzyme belonging to glycoside hydrolase family 94 from cellulolytic fungus and bacterium is cellobionic acid phosphorylase (CBAP), which catalyzes reversible phosphorolysis of CbA into glucose 1-phosphate and gluconic acid (GlcA). In this report, we describe the biochemical characterization and the three-dimensional structure of CBAP from the marine cellulolytic bacterium Saccharophagus degradans. Structures of ligand-free and complex forms with CbA, GlcA, and a synthetic disaccharide product from glucuronic acid were determined at resolutions of up to 1.6 Å. The active site is located near the dimer interface. At subsite +1, the carboxylate group of GlcA and CbA is recognized by Arg-609 and Lys-613. Additionally, one residue from the neighboring protomer (Gln-190) is involved in the carboxylate recognition of GlcA. A mutational analysis indicated that these residues are critical for the binding and catalysis of the aldonic and uronic acid acceptors GlcA and glucuronic acid. Structural and sequence comparisons with other glycoside hydrolase family 94 phosphorylases revealed that CBAPs have a unique subsite +1 with a distinct amino acid residue conservation pattern at this site. This study provides molecular insight into the energetically efficient metabolic pathway of oxidized sugars that links the oxidative cellulolytic pathway to the glycolytic and pentose phosphate pathways in cellulolytic microbes. PMID:26041776

  19. The rate of RNA degradation in human dental pulp reveals post-mortem interval.

    PubMed

    Poór, Viktor S; Lukács, Dénes; Nagy, Tamás; Rácz, Evelin; Sipos, Katalin

    2016-05-01

    Post-mortem interval (PMI) is the amount of time elapsed since the time of death. Over the years, many methods were developed to assess PMI, but their precision and time frame of applicability are often limited. Our present pilot study aimed to prove if RNA degradation of human dental pulp can be used for PMI estimation. RNA was isolated from the pulps of healthy wisdom teeth and premolars. RNA degradation was determined as RNA integrity number (RIN) with Agilent Bioanalyzer and subsequently by amplification of different length products by PCR after reverse transcription. The RNA integrity analysis allowed us to determine the time of post-mortem interval with high confidence level in the first 21 days. With the PCR-based method, we were able to perform a crude estimation of incubation time of teeth between 20 and 42 days post extraction. These results show that this method might be a promising new tool for PMI estimation despite the limitations. PMID:26608472

  20. Water evaporation rates across hydrophobic acid monolayers at equilibrium spreading pressure.

    PubMed

    Tsuji, Minami; Nakahara, Hiromichi; Moroi, Yoshikiyo; Shibata, Osamu

    2008-02-15

    The effect of alkanoic acid [CH(3)(CH(2))(n-2)COOH; HCn] and perfluoroalkanoic acid [CF(3)(CF(2))(n-2)COOH; FCn] monolayers on the water evaporation rate was investigated by thermogravimetry tracing the decrease in amount of water with time. The evaporation rate from the surface covered by a monolayer was measured as a function of temperature and hydrophobic chain length of the acids, where the monolayer was under an equilibrium spreading pressure. From thermal behavior of the crystallized acids, their solid states are C-type in crystalline state over the temperature range from 298.2 to 323.2 K. The dry air was flowed through a furnace tube of a thermogravimetry apparatus at the flow rate of 80 mL min(-1), where the evaporation rate becomes almost constant irrespective of the flow rate. The temperature dependence of the evaporation rate was analyzed kinetically to evaluate the activation energy and thermodynamics values for the activated complex, which demonstrated that these values were almost the same for both alkanoic acids and perfluoroalkanoic acids, although the effect of perfluoroalkanoic acids on the evaporation rate was smaller than that of corresponding hydrogenated fatty acids. The difference in the evaporation rate between FCn and HCn was examined by atomic force microscopy (AFM), Brewster angle microscopy (BAM), surface potential (DeltaV) at equilibrium spreading pressure, and Langmuir curve (pi-A isotherm), and their results were consistent and supported the difference. PMID:18048050

  1. Relationship between the electrochemical activity of Raney nickel and the rate of hydrogenation of maleic acid

    SciTech Connect

    Pervii, E.N.; Sofronkov, A.N.; Fedyshina, N.M.

    1986-02-10

    The purpose of this investigation was to determine the conditions in which a direct correlation exists between the rate of hydrogenation of maleic acid and the electrochemical activity of catalysts of hydrogen ionization. The rate of maleic acid hydrogenation in presence of Raney nickel catalyst was studied by a combination of volumetric and potentiometric methods.

  2. The effect of linoleic acid on the whole body synthesis rates of polyunsaturated fatty acids from α-linolenic acid and linoleic acid in free-living rats.

    PubMed

    Domenichiello, Anthony F; Kitson, Alex P; Chen, Chuck T; Trépanier, Marc-Olivier; Stavro, P Mark; Bazinet, Richard P

    2016-04-01

    Docosahexaenoic acid (DHA) is thought to be important for brain function. The main dietary source of DHA is fish, however, DHA can also be synthesized from precursor omega-3 polyunsaturated fatty acids (n-3 PUFA), the most abundantly consumed being α-linolenic acid (ALA). The enzymes required to synthesize DHA from ALA are also used to synthesize longer chain omega-6 (n-6) PUFA from linoleic acid (LNA). The large increase in LNA consumption that has occurred over the last century has led to concern that LNA and other n-6 PUFA outcompete n-3 PUFA for enzymes involved in DHA synthesis, and therefore, decrease overall DHA synthesis. To assess this, rats were fed diets containing LNA at 53 (high LNA diet), 11 (medium LNA diet) or 1.5% (low LNA diet) of the fatty acids with ALA being constant across all diets (approximately 4% of the fatty acids). Rats were maintained on these diets from weaning for 8 weeks, at which point they were subjected to a steady-state infusion of labeled ALA and LNA to measure DHA and arachidonic acid (ARA) synthesis rates. DHA and ARA synthesis rates were generally highest in rats fed the medium and high LNA diets, while the plasma half-life of DHA was longer in rats fed the low LNA diet. Therefore, increasing dietary LNA, in rats, did not impair DHA synthesis; however, low dietary LNA led to a decrease in DHA synthesis with tissue concentrations of DHA possibly being maintained by a longer DHA half-life. PMID:27012633

  3. 2,4-Dichlorophenoxyacetic acid (2,4-D)- and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T)-degrading gene cluster in the soybean root-nodulating bacterium Bradyrhizobium elkanii USDA94.

    PubMed

    Hayashi, Shohei; Sano, Tomoki; Suyama, Kousuke; Itoh, Kazuhito

    2016-01-01

    Herbicides 2,4-dichlorophenoxyacetic acid (2,4-D)- and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T)-degrading Bradyrhizobium strains possess tfdAα and/or cadABC as degrading genes. It has been reported that root-nodulating bacteria belonging to Bradyrhizobium elkanii also have tfdAα and cadA like genes but lack the ability to degrade these herbicides and that the cadA genes in 2,4-D-degrading and non-degrading Bradyrhizobium are phylogenetically different. In this study, we identified cadRABCK in the genome of a type strain of soybean root-nodulating B. elkanii USDA94 and demonstrated that the strain could degrade the herbicides when cadABCK was forcibly expressed. cadABCK-cloned Escherichia coli also showed the degrading ability. Because co-spiked phenoxyacetic acid (PAA) could induce the degradation of 2,4-D in B. elkanii USDA94, the lack of degrading ability in this strain was supposed to be due to the low inducing potential of the herbicides for the degrading gene cluster. On the other hand, tfdAα from B. elkanii USDA94 showed little potential to degrade the herbicides, but it did for 4-chlorophenoxyacetic acid and PAA. The 2,4-D-degrading ability of the cad cluster and the inducing ability of PAA were confirmed by preparing cadA deletion mutant. This is the first study to demonstrate that the cad cluster in the typical root-nodulating bacterium indeed have the potential to degrade the herbicides, suggesting that degrading genes for anthropogenic compounds could be found in ordinary non-degrading bacteria. PMID:27296963

  4. Measurement of the rates of oxindole-3-acetic acid turnover, and indole-3-acetic acid oxidation in Zea mays seedlings

    NASA Technical Reports Server (NTRS)

    Nonhebel, H. M.; Bandurski, R. S. (Principal Investigator)

    1986-01-01

    Oxindole-3-acetic acid is the principal catabolite of indole-3-acetic acid in Zea mays seedlings. In this paper measurements of the turnover of oxindole-3-acetic acid are presented and used to calculate the rate of indole-3-acetic acid oxidation. [3H]Oxindole-3-acetic acid was applied to the endosperm of Zea mays seedlings and allowed to equilibrate for 24 h before the start of the experiment. The subsequent decrease in its specific activity was used to calculate the turnover rate. The average half-life of oxindole-3-acetic acid in the shoots was found to be 30 h while that in the kernels had an average half-life of 35h. Using previously published values of the pool sizes of oxindole-3-acetic acid in shoots and kernels from seedlings of the same age and variety, and grown under the same conditions, the rate of indole-3-acetic acid oxidation was calculated to be 1.1 pmol plant-1 h-1 in the shoots and 7.1 pmol plant-1 h-1 in the kernels.

  5. Ileal apical sodium-dependent bile acid transporter protein levels are down-regulated through ubiquitin-dependent protein degradation induced by bile acids.

    PubMed

    Miyata, Masaaki; Yamakawa, Hiroki; Hayashi, Kenjiro; Kuribayashi, Hideaki; Yamazoe, Yasushi; Yoshinari, Kouichi

    2013-08-15

    The ileal apical sodium-dependent bile acid transporter (ASBT or SLC10A2) has a crucial role in intestinal bile acid absorption. We previously reported that enterobacteria-mediated bile acid conversion was involved in the alteration of ileal ASBT expression levels. In the present study, to investigate the hypothesis that ileal ASBT protein levels are post-translationally regulated by enterobacteria-associated bile acids, alteration of ileal ASBT protein levels was analysed in mice 12 h and 24 h after anti-bacterial drug ampicillin (ABPC) treatment (100 mg/kg, single shot) that altered bile acid composition in the intestinal lumen. In ABPC-treated mice, enterobacteria-biotransformed bile acid, taurodeoxycholic acid (TDCA) and cholic acid (CA) levels were decreased, whereas taurocholic acid (TCA) and tauro-β-muricholic acid levels were increased in the intestinal lumen. Ileal ASBT protein levels in brush-border membrane vesicles (BBMVs), but not ileal Asbt mRNA levels, were significantly increased in the ABPC-treated mice, and the extent of ubiquitination of the ileal ASBT protein was reduced in the ABPC-treated mice. Treatment of ABPC-pretreated mice with CA or TDCA, but not TCA, significantly decreased ileal ASBT protein levels and increased the extent of ubiquitination of ileal ASBT protein. Treatment of mice with the lysosome inhibitor, chloroquine, or the proteasome inhibitor, MG132, increased ileal ASBT protein levels in BBMVs. CA-mediated reduction of ASBT protein levels in the ABPC-pretreated mice was attenuated by co-treatment with chloroquine or MG132. These results suggest that ileal ASBT protein is degraded by a ubiquitin-dependent pathway in response to enterobacteria-associated bile acids. PMID:23872411

  6. The effect of organic acids on plagioclase dissolution rates and stoichiometry

    NASA Astrophysics Data System (ADS)

    Welch, Susan A.; Ullman, William J.

    1993-06-01

    The rates of plagioclase dissolution in solutions containing organic acids are up to ten times greater than the rates determined in solutions containing inorganic acids at the same acidity. Initial rates of dissolution are poorly reproduced in replicate experiments. After a day, however, the rates of plagioclase dissolution calculated from the rates of silicon release are reproducible and constant for up to nineteen days. Steady-state rates of dissolution are highest (up to 1.3 × 10 -8 mol/m 2/sec) in acidic solutions (pH ≈ 3) and decrease (to 1 × 10 -11 mol/m 2/sec) as acidity decreases toward neutral pH. The polyfunctional acids, oxalate, citrate, succinate, pyruvate, and 2-ketoglutarate, are the most effective at promoting dissolution. Acetate and propionate are not as effective as the other organic acids but are nonetheless more effective than solutions containing only inorganic acids. The degree of ligand-promoted enhancement of dissolution rate (rate in organic-containing solution/rate in inorganic solution at the same pH) decreases as acidity increases, indicating that the ligand-promoted dissolution mechanism becomes relatively more important as the rate of proton-promoted dissolution decreases. The stoichiometry of release to solution indicates that dissolution is selective even after the rates of dissolution become constant. As in previously published studies, Na and Ca are rapidly released from the plagioclase feldspar, leaving a surface enriched in Si and/or Al. The ratio of Al/Si released to solution indicates that the stoichiometry of the residual plagioclase surface is a function of pH and the nature of the organic ligand. The ligands which remove Al in preference to Si from the dissolving mineral surface are also those which enhance overall plagioclase dissolution rates.

  7. Sono-assisted photocatalytic degradation of styrene-acrylic acid copolymer in aqueous media with nano titania particles and kinetic studies.

    PubMed

    Saien, J; Delavari, H; Solymani, A R

    2010-05-15

    The ultrasonic irradiation (28 kHz, 50 W) in pre-cavitations regime was employed to enhance the degradation rate of styrene-acrylic acid copolymer in aqueous media with nano titania photocatalyst particles. A stainless steel cylindrical sono-photo reactor with capacity of about 1.25 L, equipped with a UV lamp (250 W) was used. The influence of operational parameters, i.e. catalyst concentration, pH and temperature was studied and the role of active species was also distinguished. For an initial substrate concentration of 30 mg L(-1), under mild applied conditions of 30 mg L(-1) of photocatalyst, 25 degrees C and natural pH, a degradation and mineralization conversion of 96% and 91%, respectively, was achieved using sono-assisted photocatalysis process in about only 60 min. These efficiencies are much higher than those obtained with only photocatalysis process. Meanwhile, the threshold of cavitations was found corresponded to catalyst concentration of about 70 mg L(-1). Kinetic studies based on Langmuir-Hinshelwood and power law models in addition to the results from radical scavenger usage revealed that for sono-assisted process, the substrate undergoes degradation mainly via electron-hole redox on the surface of titania particles. It is while for the only photocatalysis process, the reaction proceeds via hydroxyl radicals in the solution bulk. PMID:20092940

  8. Laboratory Assessment of a Screening Model: Exploring the Coupling between Dissolution and Degradation Rates in Ganglia-Dominated Source Zones

    NASA Astrophysics Data System (ADS)

    Phelan, T. J.; Abriola, L. M.; Gibson, J. L.; Smits, K. M.; Christ, J.

    2014-12-01

    In-situ bioremediation is a widely applied treatment technology for source zones contaminated with dense non-aqueous phase liquids (DNAPLs). It is both economical and reasonably efficient for long-term management and closure of contaminated sites. A number of laboratory studies have demonstrated enhancement in chlorinated ethene dissolution rates due to the presence of dehalogenating microorganisms, which may lead to increased mass removal rates and shorter cleanup times. Previous modeling efforts have suggested this dissolution enhancement can be a factor of 10 or more when the contaminant is located in high saturation DNAPL pools. Yet, laboratory studies with DNAPL trapped as ganglia have suggested dissolution enhancement is often less than 10. This presentation investigates the interplay between dissolution and degradation rates in ganglia-contaminated source zones using a one-dimensional, simplified, steady-state, analytical solution to the advection-dispersion-reaction equation. A linear driving force model is employed to simulate ganglia dissolution. Degradation kinetics are approximated as zero- or first-order. Model predictions are independently compared to laboratory data available in the literature. Results indicate that dissolution enhancement predictions in ganglia-dominated source zones are often much less than those predicted assuming high saturation pools, suggesting that the presented model is a better tool for estimating bioenhanced dissolution in ganglia-contaminated regions. Furthermore, this screening model provides a remarkably good prediction of laboratory results and could provide practitioners with a useful tool for estimating the extent to which bioenhanced dissolution may aid in site closure strategies.

  9. Laboratory Validation of a Screening Model: Exploring the Interplay between Dissolution and Degradation Rates in Ganglia-Dominated Source Zones

    NASA Astrophysics Data System (ADS)

    Phelan, T. J.; Abriola, L. M.; Gibson, J. L.; Smits, K. M.; Christ, J.

    2013-12-01

    In-situ bioremediation is a widely applied treatment technology for source zones contaminated with dense non-aqueous phase liquids (DNAPLs). It is both economical and reasonably efficient for long-term management and closure of contaminated sites. A number of laboratory studies have demonstrated enhancement in chlorinated ethene dissolution rates due to the presence of dehalogenating microorganisms, which may lead to increased mass removal rates and shorter cleanup times. Previous modeling efforts have suggested this dissolution enhancement can be a factor of 10 or more when the contaminant is located in high saturation DNAPL pools. Yet, laboratory studies with DNAPL trapped as ganglia have suggested dissolution enhancement is often less than 10. This presentation investigates the interplay between dissolution and degradation rates in ganglia-contaminated source zones using a one-dimensional, simplified, steady-state, analytical solution to the advection-dispersion-reaction equation. A linear driving force model is employed to simulate ganglia dissolution. Degradation kinetics are approximated as zero- or first-order. Model predictions are independently compared to laboratory data available in the literature. Results indicate that dissolution enhancement predictions in ganglia-dominated source zones are often much less than those predicted assuming high saturation pools, suggesting that the presented model is a better tool for estimating bioenhanced dissolution in ganglia-contaminated regions. Furthermore, this screening model provides a remarkably good prediction of laboratory results and could provide practitioners with a useful tool for estimating the extent to which bioenhanced dissolution may aid in site closure strategies.

  10. Energetics and kinetics of anaerobic aromatic and fatty acid degradation. Progress report, November 1992--November 1993

    SciTech Connect

    McInerney, M.J.

    1993-11-12

    The kinetics of benzoate degradation by the anaerobic syntrophic bacterium, Syntrophus buswellii, in coculture with different sulfate reducers was studied with sulfate or nitrate as the electron acceptor. A threshold value for benzoate degradation dependent on the acetate concentration was observed with sulfate, but not nitrate, as the electron acceptor. No threshold was observed in tricultures containing an acetate-using sulfate reducer. The addition of the acetate-using sulfate reducer to cocultures that had degraded benzoate to its threshold value resulted in further degradation of benzoate to levels below the analytical detection limit (ca. 200 nM). These data are consistent with a thermodynamic explanation for the threshold, and exclude the possibility that the threshold was the result of the inhibitory action of the undissociated form of acetate.

  11. Amino acids in the Pearl River Estuary and adjacent waters: origins, transformation and degradation

    NASA Astrophysics Data System (ADS)

    Chen, Jianfang; Li, Yan; Yin, Kedong; Jin, Haiyan

    2004-10-01

    Two cruises were conducted in the Pearl River Estuary (PRE) and adjacent coastal waters during July 1999 and 2000 to investigate spatial variation, transformation and degradation of amino acids (AAs). Salinity, suspended sediments (SS), chl a, nutrients, dissolved organic carbon, particulate organic carbon, AAs, and hexosamines were measured and analyzed. Concentrations of particulate hydrolysable AAs (PHAAs), dissolved combined AAs and dissolved free AAs ranged from 0.41 to 12.6 μmol L-1, 1.1 to 4.0 μmol L-1 and 0.15 to 1.10 μmol L-1, respectively. AAs concentrations were low in waters of salinity <10, increased to the maximum in the estuarine and coastal plumes (salinity =10-25) and decreased beyond the coastal plume. There was a region where PHAAs were maximum, which coincided with the region of the chl a maximum and depletion of dissolved inorganic phosphorus in the coastal plume south of Hong Kong. This indicates that most of the AAs in estuarine and coastal waters were produced through phytoplankton production and AAs might be a temporary sink for inorganic nitrogen. The ratios of AAs/HAs and glucosamine/galactosamine (Glc-NH2/Gal-NH2) were on average, 26.0 and 3.8, respectively, in biogenic particulate matter (chl a >5 μg L-1 and SS<10 mg L-1), decreased in turbid particles (SS>20 mg L-1) and reached the lowest values of 5.8 and 1.4 in sediments. In particular, the ratios of AAs/HAs, Glc-NH2/Gal-NH2 were low in the upper or northwest side of the estuary where turbidity was high. This indicated that these AAs were "old", likely due to resuspension of refractory organic matter from sediments or zooplankton grazing modification and bacterial reworking as the salt wedge advanced upstream near the bottom. Apparently, the dynamics of AAs in the PRE appeared to be governed by biological production processes and estuarine circulation in the estuary. As the chl a maximum developed downstream in the estuarine and coastal plume and the salt wedge moved upstream at

  12. The Fate and Transport of Glyphosate and its Degradation Product, Aminomethylphosphonic Acid (AMPA), in Water

    NASA Astrophysics Data System (ADS)

    Scribner, E.; Meyer, M. T.

    2006-05-01

    Since 2001, the U.S. Geological Survey (USGS) has investigated the fate and transport of glyphosate and its degradation product, aminomethylphosphonic acid (AMPA), in surface water, and more recently in tile-drain flow, soil, and wet deposition. According to U.S. Environmental Protection Agency sources, glyphosate is among the world's most widely used herbicides. In 2004, glyphosate usage estimates indicated that between 103 and 113 million pounds were applied annually to crops in the United States. The use of glyphosate over a wide geographic area suggests that this herbicide might be a potential concern for air, water, and soil quality as well as measured in high concentrations in streams; therefore, it is important to monitor its fate and transport in ground-water/surface-water systems. National, regional, and field-scale studies conducted by the USGS National Water-Quality Assessment and Toxic Substance Hydrology Programs have studied the fate and transport of glyphosate in overland flow, tile- drain flow, surface water, soil, and wet-deposition samples. The samples were analyzed for glyphosate and AMPA by using derivatization and online solid-phase extraction with liquid chromatography/mass spectrometry (LC/MS) and LC/MS/MS methods developed by the USGS Organic Geochemistry Research Laboratory in Lawrence, Kansas. During spring, summer, and fall 2002 runoff periods in 50 Midwestern streams, glyphosate was detected at or above the 0.10 micrograms per liter detection limit in 35, 41, and 31 percent of samples, respectively. AMPA was detected in 53, 82, and 75 percent of samples, respectively. Results of 128 samples from a field study showed that glyphosate was transported as a narrow high- concentration pulse during the first period of runoff after application and that the concentration of glyphosate in runoff was greater than the concentration of AMPA. In tile-drain flow, glyphosate and AMPA were transported in a broad low-concentration pulse during these same

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

    PubMed Central

    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.

    2010-01-01

    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 (PHA), lactobionic acid (LBA), or gluconolactone (GL). Applications of the PHA reduced the pH at all levels of SC of hairless mouse, with further selective acidification of SC membrane domains, as shown by fluorescence lifetime imaging. Hyperacidification improved permeability barrier homeostasis, attributable to increased activities of two key membrane-localized, ceramide-generating hydrolytic enzymes (β-glucocerebrosidase and acidic sphingomyelinase), which correlated with accelerated extracellular maturation of SC lamellar membranes. Hyperacidification generated “supernormal” SC integrity/cohesion, attributable to an SP-dependent decreased degradation of desmoglein-1 (DSG1) and the induction of DSG3 expression in lower SC. As SC hyperacidification improves the structure and function, even of normal epidermis, these studies lay the groundwork for an assessment of the potential utility of SC acidification as a therapeutic strategy for inflammatory dermatoses, characterized by abnormalities in barrier function, cohesion, and surface pH. PMID:19741713

  14. Acute acidification of stratum corneum membrane domains using polyhydroxyl acids improves lipid processing and inhibits degradation of corneodesmosomes.

    PubMed

    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

    2010-02-01

    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 (PHA), lactobionic acid (LBA), or gluconolactone (GL). Applications of the PHA reduced the pH at all levels of SC of hairless mouse, with further selective acidification of SC membrane domains, as shown by fluorescence lifetime imaging. Hyperacidification improved permeability barrier homeostasis, attributable to increased activities of two key membrane-localized, ceramide-generating hydrolytic enzymes (beta-glucocerebrosidase and acidic sphingomyelinase), which correlated with accelerated extracellular maturation of SC lamellar membranes. Hyperacidification generated "supernormal" SC integrity/cohesion, attributable to an SP-dependent decreased degradation of desmoglein-1 (DSG1) and the induction of DSG3 expression in lower SC. As SC hyperacidification improves the structure and function, even of normal epidermis, these studies lay the groundwork for an assessment of the potential utility of SC acidification as a therapeutic strategy for inflammatory dermatoses, characterized by abnormalities in barrier function, cohesion, and surface pH. PMID:19741713

  15. Oxidative degradation of bis (2,4,4-trimethylpentyl) dithiophosphinic acid in nitric acid studied by electrospray ionization mass spectrometry

    SciTech Connect

    G. S. Groenewold; D. R. Peterman

    2012-10-01

    Samples of bis(2,4,4-trimethylpentyl)dithiophosphinic acid (Cyanex-301) were analyzed using direct infusion electrospray ionization mass spectrometry. Positive ion spectra of standard and stereo-pure acids displayed ions typical of the unmodified compound, cationized monomeric and dimeric cluster ion species. In addition, a significant ions 2 u less than the dimeric clusters were seen, that correspond to an oxidatively coupled species designated Cyx2 that is observed as H- or Na-cationized species in the electrospray analyses. Based on uncorrected ion intensities, Cyx2 is estimated to account for about 20% of the total in the standard materials. When samples that were contacted with 3 M HNO3 were analyzed, the positive ion spectrum consisted nearly entirely of ions derived from the oxidatively coupled product, indicating that the acid promotes coupling. The negative ion spectra of the standard acids consisted nearly entirely of the conjugate base that is formed by deprotonation of the acids, and cluster ions containing multiple acid molecules. The negative spectra of the HNO3-contacted samples also contained the conjugate base of the unmodified acid, but also two other species that correspond to the dioxo- and perthio- derivatives. It is concluded that HNO3 contact causes significant oxidation, forming at least three major products, Cyx2, the perthio-acid, and the dioxo-acid.

  16. Changes in fermentation and biohydrogenation intermediates in continuous cultures fed low and high levels of fat with increasing rates of starch degradability.

    PubMed

    Lascano, G J; Alende, M; Koch, L E; Jenkins, T C

    2016-08-01

    Excessive levels of starch in diets for lactating dairy cattle is a known risk factor for milk fat depression, but little is known about how this risk is affected by differences in rates of starch degradability (Kd) in the rumen. The objective of this study was to compare accumulation of biohydrogenation intermediates causing milk fat depression, including conjugated linoleic acid (CLA), when corn with low or high Kd were fed to continuous cultures. Diets contained (dry matter basis) 50% forage (alfalfa pellets and grass hay) and 50% concentrate, with either no added fat (LF) or 3.3% added soybean oil (HF). Within both the LF and HF diets, 3 starch degradability treatments were obtained by varying the ratio of processed (heat and pressure treatments) and unprocessed corn sources, giving a total of 6 dietary treatments. Each diet was fed to dual-flow continuous fermenters 3 times a day at 0800, 1600, and 2400h. Diets were fed for four 10-d periods, with 7d for adaptation and 3d for sample collection. Orthogonal contrasts were used in the GLIMMIX procedure of SAS to test the effects of fat, starch degradability, and their interaction. Acetate and acetate:propionate were lower for HF than for LF but daily production of trans-10 18:1 and trans-10,cis-12 CLA were higher for HF than for LF. Increasing starch Kd from low to high increased culture pH, acetate, and valerate but decreased butyrate and isobutyrate. Changes in biohydrogenation intermediates (expressed as % of total isomers) from low to high starch Kd included reductions in trans-11 18:1 and cis-9,trans-11 CLA but increases in trans-10 18:1 and trans-10,cis-12 CLA. The results show that increasing the starch Kd in continuous cultures while holding starch level constant causes elevation of biohydrogenation intermediates linked to milk fat depression. PMID:27265165

  17. Cytokine regulation of human lung fibroblast hyaluronan (hyaluronic acid) production. Evidence for cytokine-regulated hyaluronan (hyaluronic acid) degradation and human lung fibroblast-derived hyaluronidase.

    PubMed Central

    Sampson, P M; Rochester, C L; Freundlich, B; Elias, J A

    1992-01-01

    We characterized the mechanisms by which recombinant (r) tumor necrosis factor (TNF), IFN-gamma, and IL-1, alone and in combination, regulate human lung fibroblast hyaluronic acid (HA) production. Each cytokine stimulated fibroblast HA production. The combination of rTNF and rIFN-gamma resulted in a synergistic increase in the production of high molecular weight HA. This was due to a synergistic increase in hyaluronate synthetase activity and a simultaneous decrease in HA degradation. In contrast, when rTNF and rIL-1 were combined, an additive increase in low molecular weight HA was noted. This was due to a synergistic increase in hyaluronate synthetase activity and a simultaneous increase in HA degradation. Human lung fibroblasts contained a hyaluronidase that, at pH 3.7, depolymerized high molecular weight HA to 10-40 kD end products of digestion. However, hyaluronidase activity did not correlate with fibroblast HA degradation. Instead, HA degradation correlated with fibroblast-HA binding, which was increased by rIL-1 plus rTNF and decreased by rIFN-gamma plus rTNF. Recombinant IL-1 and rTNF weakly stimulated and rIL-1 and rTNF in combination further augmented the levels of CD44 mRNA in lung fibroblasts. In contrast, rIFN-gamma did not significantly alter the levels of CD44 mRNA in unstimulated or rTNF stimulated cells. These studies demonstrate that rIL-1, rTNF, and rIFN-gamma have complex effects on biosynthesis and degradation which alter the quantity and molecular weight of the HA produced by lung fibroblasts. They also show that fibroblast HA degradation is mediated by a previously unrecognized lysosomal-type hyaluronidase whose function may be regulated by altering fibroblast-HA binding. Lastly, they suggest that the CD44 HA receptor may be involved in this process. Images PMID:1401082

  18. Dissolution rates of carbonated hydroxyapatite in hydrochloric acid.

    PubMed

    Hankermeyer, Christine R; Ohashi, Kevin L; Delaney, David C; Ross, John; Constantz, Brent R

    2002-02-01

    Osteoclasts have been shown to dissolve efficiently and effectively the mineral phase of bone by locally controlling the environment surrounding the cell. Although this mineral phase has been identified and well characterized as carbonated hydroxyapatite, there is little understanding of the factors that affect the dissolution properties of this mineral phase. Mimicking the mechanism by which osteoclasts dissolve the mineral phase of bone may provide insight into methods for the decalcification of atherosclerotic mineral deposits in the vascular system. Accordingly, a detailed characterization of the effects of various chemical and mechanical parameters on the dissolution of carbonated hydroxyapatite mineral was investigated in this study. Increases in the mineral dissolution rate (2-10 times) were associated with increases in dissolving solution [H+], osmolality, temperature, and flow rate. Mineral dissolution rate increases (5-8 times) were associated with greater surface area of the mineral and mechanical agitation of the dissolving solution. PMID:11771694

  19. A Stability-Indicating HPLC-DAD Method for Determination of Ferulic Acid into Microparticles: Development, Validation, Forced Degradation, and Encapsulation Efficiency.

    PubMed

    Nadal, Jessica Mendes; Toledo, Maria da Graça; Pupo, Yasmine Mendes; Padilha de Paula, Josiane; Farago, Paulo Vitor; Zanin, Sandra Maria Warumby

    2015-01-01

    A simple stability-indicating HPLC-DAD method was validated for the determination of ferulic acid (FA) in polymeric microparticles. Chromatographic conditions consisted of a RP C18 column (250 mm × 4.60 mm, 5 μm, 110 Å) using a mixture of methanol and water pH 3.0 (48 : 52 v/v) as mobile phase at a flow rate of 1.0 mL/min with UV detection at 320 nm. The developed method was validated as per ICH guidelines with respect to specificity, linearity, limit of quantification, limit of detection, accuracy, precision, and robustness provided suitable results regarding all parameters investigated. The calibration curve was linear in the concentration range of 10.0-70.0 μg/mL with a correlation coefficient >0.999. Precision (intraday and interday) was demonstrated by a relative standard deviation lower than 2.0%. Accuracy was assessed by the recovery test of FA from polymeric microparticles (99.02% to 100.73%). Specificity showed no interference from the components of polymeric microparticles or from the degradation products derived from acidic, basic, and photolytic conditions. In conclusion, the method is suitable to be applied to assay FA as bulk drug and into polymeric microparticles and can be used for studying its stability and degradation kinetics. PMID:26075139

  20. PEGylated single-walled carbon nanotubes activate neutrophils to increase production of hypochlorous acid, the oxidant capable of degrading nanotubes

    SciTech Connect

    Vlasova, Irina I.; Vakhrusheva, Tatyana V.; Sokolov, Alexey V.; Kostevich, Valeria A.; Gusev, Alexandr A.; Gusev, Sergey A.; Melnikova, Viktoriya I.; Lobach, Anatolii S.

    2012-10-01

    Perspectives for the use of carbon nanotubes in biomedical applications depend largely on their ability to degrade in the body into products that can be easily cleared out. Carboxylated single-walled carbon nanotubes (c-SWCNTs) were shown to be degraded by oxidants generated by peroxidases in the presence of hydrogen peroxide. In the present study we demonstrated that conjugation of poly(ethylene glycol) (PEG) to c-SWCNTs does not interfere with their degradation by peroxidase/H{sub 2}O{sub 2} system or by hypochlorite. Comparison of different heme-containing proteins for their ability to degrade PEG-SWCNTs has led us to conclude that the myeloperoxidase (MPO) product hypochlorous acid (HOCl) is the major oxidant that may be responsible for biodegradation of PEG-SWCNTs in vivo. MPO is secreted mainly by neutrophils upon activation. We hypothesize that SWCNTs may enhance neutrophil activation and therefore stimulate their own biodegradation due to MPO-generated HOCl. PEG-SWCNTs at concentrations similar to those commonly used in in vivo studies were found to activate isolated human neutrophils to produce HOCl. Both PEG-SWCNTs and c-SWCNTs enhanced HOCl generation from isolated neutrophils upon serum-opsonized zymosan stimulation. Both types of nanotubes were also found to activate neutrophils in whole blood samples. Intraperitoneal injection of a low dose of PEG-SWCNTs into mice induced an increase in percentage of circulating neutrophils and activation of neutrophils and macrophages in the peritoneal cavity, suggesting the evolution of an inflammatory response. Activated neutrophils can produce high local concentrations of HOCl, thereby creating the conditions favorable for degradation of the nanotubes. -- Highlights: ► Myeloperoxidase (MPO) product hypochlorous acid is able to degrade CNTs. ► PEGylated SWCNTs stimulate isolated neutrophils to produce hypochlorous acid. ► SWCNTs are capable of activating neutrophils in blood samples. ► Activation of

  1. Determination of degradation rates of organic substances in the unsaturated soil zone depending on the grain size fractions of various soil types

    NASA Astrophysics Data System (ADS)

    Fichtner, Thomas; Stefan, Catalin; Goersmeyer, Nora

    2015-04-01

    Rate and extent of the biological degradation of organic substances during transport through the unsaturated soil zone is decisively influenced by the chemical and physical properties of the pollutants such as water solubility, toxicity and molecular structure. Furthermore microbial degradation processes are also influenced by soil-specific properties. An important parameter is the soil grain size distribution on which the pore volume and the pore size depends. Changes lead to changes in air and water circulation as well as preferred flow paths. Transport capacity of water inclusive nutrients is lower in existing bad-drainable fine pores in soils with small grain size fractions than in well-drainable coarse pores in a soil with bigger grain size fractions. Because fine pores are saturated with water for a longer time than the coarse pores and oxygen diffusion in water is ten thousand times slower than in air, oxygen is replenished much slower in soils with small grain size fractions. As a result life and growth conditions of the microorganisms are negatively affected. This leads to less biological activity, restricted degradation/mineralization of pollutants or altered microbial processes. The aim of conducted laboratory column experiments was to study the correlation between the grain size fractions respectively pore sizes, the oxygen content and the biodegradation rate of infiltrated organic substances. Therefore two columns (active + sterile control) were filled with different grain size fractions (0,063-0,125 mm, 0,2-0,63 mm and 1-2 mm) of soils. The sterile soil was inoculated with a defined amount of a special bacteria culture (sphingobium yanoikuae). A solution with organic substances glucose, oxalic acid, sinaphylic alcohol and nutrients was infiltrated from the top in intervals. The degradation of organic substances was controlled by the measurement of dissolved organic carbon in the in- and outflow of the column. The control of different pore volumes

  2. Evaluating the interaction of faecal pellet deposition rates and DNA degradation rates to optimize sampling design for DNA-based mark-recapture analysis of Sonoran pronghorn.

    PubMed

    Woodruff, S P; Johnson, T R; Waits, L P

    2015-07-01

    Knowledge of population demographics is important for species management but can be challenging in low-density, wide-ranging species. Population monitoring of the endangered Sonoran pronghorn (Antilocapra americana sonoriensis) is critical for assessing the success of recovery efforts, and noninvasive DNA sampling (NDS) could be more cost-effective and less intrusive than traditional methods. We evaluated faecal pellet deposition rates and faecal DNA degradation rates to maximize sampling efficiency for DNA-based mark-recapture analyses. Deposition data were collected at five watering holes using sampling intervals of 1-7 days and averaged one pellet pile per pronghorn per day. To evaluate nuclear DNA (nDNA) degradation, 20 faecal samples were exposed to local environmental conditions and sampled at eight time points from one to 124 days. Average amplification success rates for six nDNA microsatellite loci were 81% for samples on day one, 63% by day seven, 2% by day 14 and 0% by day 60. We evaluated the efficiency of different sampling intervals (1-10 days) by estimating the number of successful samples, success rate of individual identification and laboratory costs per successful sample. Cost per successful sample increased and success and efficiency declined as the sampling interval increased. Results indicate NDS of faecal pellets is a feasible method for individual identification, population estimation and demographic monitoring of Sonoran pronghorn. We recommend collecting samples <7 days old and estimate that a sampling interval of four to seven days in summer conditions (i.e., extreme heat and exposure to UV light) will achieve desired sample sizes for mark-recapture analysis while also maximizing efficiency [Corrected]. PMID:25522240

  3. Application of vibrational spectroscopy in the in vitro studies of carbon fiber-polylactic acid composite degradation.

    NASA Astrophysics Data System (ADS)

    Blazewicz, Marta; Gajewska, Maria Chomyszyn; Paluszkiewicz, Czeslawa

    1999-05-01

    Vibrational spectroscopy was used for assessment of new material for stomatology, for guided tissue regeneration (GTR) techniqe.Implants applied in the healing of periodontal defects using GTR technique have to meet stringent requirements concerning their chemical as well physical properties.At present the implants prepared from two layers membranes differing in porosity in their outer and inner layers are studied clinically. Composite plates prepared by us consist of three layers: polylactic acid film, carbon fibres coated with polylactic acid and carbon fabric.Vibrational spectroscopic studies of the material; polylactic acid- carbon fiber have made it possible to analyse chemical reactions occurring between the polymer and carbon surface. Analysis of the IR spectra of samples treated in Ringer solution allowed to describe the phenomena resulting from the composite degradation. It was shown that material biostability is related to the presence of carbon fibers.

  4. Perfluorinated carboxylic and sulphonic acids in surface water media from the regions of Tibetan Plateau: Indirect evidence on photochemical degradation?

    PubMed

    Yamazaki, Eriko; Falandysz, Jerzy; Taniyasu, Sachi; Hui, Ge; Jurkiewicz, Gabriela; Yamashita, Nobuyoshi; Yang, Yong-Liang; Lam, Paul K S

    2016-01-01

    Perfluorinated surfactants and repellents are synthetic substances that have found numerous industrial and customer applications. Due to their persistence, at least two groups of these substances-perfluorinated carboxylic acids (PFCAs) and perfluorinated sulfonic acids (PFSAs)-are diffused widely in the environment. It is hypothesized that the Tibetan Plateau, is one of few unique places on the Earth, due to its topography, specifically the vast space and high elevation above sea level, geographic location, climate, high solar radiation, lack of industry, little urbanization and general lack of significant direct sources of pollution. There it is believed possible to gain an insight into atmospheric fate (possible photochemical degradation of higher molecular mass and formation of lower molecular mass PFCAs and PFSAs) of PFASs under un-disturbed environmental conditions. Ultratrace analytical method for PFCAs and PFSAs and use of transportation and field blanks, laboratory blanks and isotopically labelled surrogates for recovery control has allowed the determination of nine perfluorinated carboxylic acids and six perfluorinated sulfonic acids at ultra-trace levels in water based samples from the alpine dimension regions of the Tibetan Plateau, the eastern slope of Minya Konka peak at the eastern edge of the Tibetan Plateau, and also from the city of Chengdu from the lowland of the Sichuan Province in China. The specific compositional pattern of PFCAs and PFSAs and low levels of pollution with those compounds were observed in the central region of the Tibetan Plateau and in the region adjacent to the peaks of Minya Konka in the Eastern Tibetan Plateau. The fingerprint of the compositional pattern of PFCAs and PFSAs in water samples in the central region of the Tibetan Plateau and in the alpine region adjacent to the peaks of Minya Konka in the Eastern Tibetan Plateau may be explained by the result of photochemical degradation with dealkylation of longer chain

  5. The cellular growth rate controls overall mRNA turnover, and modulates either transcription or degradation rates of particular gene regulons

    PubMed Central

    García-Martínez, José; Delgado-Ramos, Lidia; Ayala, Guillermo; Pelechano, Vicent; Medina, Daniel A.; Carrasco, Fany; González, Ramón; Andrés-León, Eduardo; Steinmetz, Lars; Warringer, Jonas; Chávez, Sebastián; Pérez-Ortín, José E.

    2016-01-01

    We analyzed 80 different genomic experiments, and found a positive correlation between both RNA polymerase II transcription and mRNA degradation with growth rates in yeast. Thus, in spite of the marked variation in mRNA turnover, the total mRNA concentration remained approximately constant. Some genes, however, regulated their mRNA concentration by uncoupling mRNA stability from the transcription rate. Ribosome-related genes modulated their transcription rates to increase mRNA levels under fast growth. In contrast, mitochondria-related and stress-induced genes lowered mRNA levels by reducing mRNA stability or the transcription rate, respectively. We also detected these regulations within the heterogeneity of a wild-type cell population growing in optimal conditions. The transcriptomic analysis of sorted microcolonies confirmed that the growth rate dictates alternative expression programs by modulating transcription and mRNA decay. The regulation of overall mRNA turnover keeps a constant ratio between mRNA decay and the dilution of [mRNA] caused by cellular growth. This regulation minimizes the indiscriminate transmission of mRNAs from mother to daughter cells, and favors the response capacity of the latter to physiological signals and environmental changes. We also conclude that, by uncoupling mRNA synthesis from decay, cells control the mRNA abundance of those gene regulons that characterize fast and slow growth. PMID:26717982

  6. The cellular growth rate controls overall mRNA turnover, and modulates either transcription or degradation rates of particular gene regulons.

    PubMed

    García-Martínez, José; Delgado-Ramos, Lidia; Ayala, Guillermo; Pelechano, Vicent; Medina, Daniel A; Carrasco, Fany; González, Ramón; Andrés-León, Eduardo; Steinmetz, Lars; Warringer, Jonas; Chávez, Sebastián; Pérez-Ortín, José E

    2016-05-01

    We analyzed 80 different genomic experiments, and found a positive correlation between both RNA polymerase II transcription and mRNA degradation with growth rates in yeast. Thus, in spite of the marked variation in mRNA turnover, the total mRNA concentration remained approximately constant. Some genes, however, regulated their mRNA concentration by uncoupling mRNA stability from the transcription rate. Ribosome-related genes modulated their transcription rates to increase mRNA levels under fast growth. In contrast, mitochondria-related and stress-induced genes lowered mRNA levels by reducing mRNA stability or the transcription rate, respectively. We also detected these regulations within the heterogeneity of a wild-type cell population growing in optimal conditions. The transcriptomic analysis of sorted microcolonies confirmed that the growth rate dictates alternative expression programs by modulating transcription and mRNA decay.The regulation of overall mRNA turnover keeps a constant ratio between mRNA decay and the dilution of [mRNA] caused by cellular growth. This regulation minimizes the indiscriminate transmission of mRNAs from mother to daughter cells, and favors the response capacity of the latter to physiological signals and environmental changes. We also conclude that, by uncoupling mRNA synthesis from decay, cells control the mRNA abundance of those gene regulons that characterize fast and slow growth. PMID:26717982

  7. Validating a Stability Indicating HPLC Method for Kinetic Study of Cetirizine Degradation in Acidic and Oxidative Conditions

    PubMed Central

    Souri, Effat; Hatami, Ali; Shabani Ravari, Nazanin; Alvandifar, Farhad; Barazandeh Tehrani, Maliheh

    2013-01-01

    A stability indicating High-Performance Liquid Chromatography (HPLC) method was validated and used to study the degradation of cetirizine dihydrochloride in acidic and oxidative conditions. The separation was carried out on a Symmetry C18 column and a mixture of 50 mM KH2PO4 and acetonitrile (60:40 v/v, pH = 3.5) was used as the mobile phase. The method was linear over the range of 1-20 μg/mL of cetirizine dihydrochloride (r2 > 0.999) and the within-day and between-day precision values were less than 1.5%. The results showed that cetirizine dihydrochloride was unstable in 2 M HCl and 0.5% H2O2. The kinetics of the acidic degradation showed a pseudo-first-order reaction in the temperature range of 70-90°C. In addition, the kinetics of hydrogen peroxide mediated degradation was pseudo-first-order in the temperature range of 50-80°C. PMID:24250602

  8. The oxidative degradation of barley β-glucan in the presence of ascorbic acid or hydrogen peroxide.

    PubMed

    Mäkelä, Noora; Sontag-Strohm, Tuula; Maina, Ndegwa Henry

    2015-06-01

    Cereal β-glucans are polysaccharides with health benefits that have been linked to their ability to increase luminal viscosity. However, the functional properties of cereal β-glucans may be diminished by the susceptibility of this polysaccharide to oxidative degradation. In this study, barley β-glucan was oxidised with hydrogen peroxide or ascorbic acid and the oxidative degradation of β-glucan was investigated using both asymmetrical flow field-flow fractionation (AsFlFFF) with aqueous solvent and high performance size exclusion chromatography (HPSEC) with LiBr in DMSO as the solvent. Oxidation was shown to cause degradation of β-glucan, the reaction being faster when oxidised with hydrogen peroxide compared with ascorbic acid. Both HPSEC and AsFlFFF showed comparable results as long as aggregates (only observed in AsFlFFF) were not included in the integration. The compact aggregates observed in oxidised samples suggest oxidation driven interactions between β-glucan molecules. PMID:25843872

  9. Effects of polyunsaturated fatty acid supplementation on ruminal in situ forage degradability, performance, and physiological responses of feeder cattle.

    PubMed

    Cooke, R F; Bohnert, D W; Moriel, P; Hess, B W; Mills, R R

    2011-11-01

    Two experiments were conducted to compare ruminal, physiological, and performance responses of forage-fed cattle consuming grain-based supplements without (NF) or with the inclusion (10%; DM basis) of a rumen-protected PUFA (PF) or SFA source (SF). Supplements were offered and consumed at 0.6% of BW/animal daily (DM basis). In Exp. 1, DMI and ruminal in situ forage degradability were evaluated in 3 Angus × Hereford cows fitted with ruminal cannulas and allocated to a 3 × 3 Latin square design. Within each experimental period, hay was offered in amounts to ensure ad libitum access from d 1 to 13, DMI was recorded from d 8 to 13, and cows were limited to receive 90% of their average hay DMI (d 1 to 13) from d 14 to 21. On d 16, polyester bags containing 4 g of ground hay (DM basis) were incubated within the rumen of each cow for 0, 4, 8, 12, 24, 36, 48, 72, and 96 h. Hay and total DMI were reduced (P < 0.05) in cows receiving PF compared with cows receiving SF and NF. No treatment effects were detected (P > 0.48) for ruminal disappearance rate and effective ruminal degradability of hay DM and NDF. In Exp. 2, preconditioning DMI, ADG, carcass traits, and plasma concentrations of cortisol, fatty acids, acute-phase proteins, and proinflammatory cytokines were assessed in 72 Angus × Hereford steers receiving supplement treatments during a 28-d preconditioning period. All steers were transported to a commercial growing lot after preconditioning (d 1) and were later moved to an adjacent commercial finishing yard (d 144), where they remained until slaughter. No treatment effects were detected (P ≥ 0.52) for preconditioning ADG and G:F, but DMI tended (P = 0.09) to be reduced in steers receiving PF compared with those receiving NF and SF. Plasma PUFA concentrations were greater in steers receiving PF compared with those receiving NF and SF (P = 0.01). After transportation, concentration of tumor necrosis factor-α increased for steers receiving NF, did not change for

  10. The ergosterol biosynthesis inhibitor zaragozic acid promotes vacuolar degradation of the tryptophan permease Tat2p in yeast.

    PubMed

    Daicho, Katsue; Maruyama, Hironori; Suzuki, Asuka; Ueno, Masaru; Uritani, Masahiro; Ushimaru, Takashi

    2007-07-01

    Ergosterol is the yeast functional equivalent of cholesterol in mammalian cells. Deletion of the ERG6 gene, which encodes an enzyme catalyzing a late step of ergosterol biosynthesis, impedes targeting of the tryptophan permease Tat2p to the plasma membrane, but does not promote vacuolar degradation. It is unknown whether similar features appear when other steps of ergosterol biogenesis are inhibited. We show herein that the ergosterol biosynthesis inhibitor zaragozic acid (ZA) evoked massive vacuolar degradation of Tat2p, accompanied by a decrease in tryptophan uptake. ZA inhibits squalene synthetase (SQS, EC 2.5.1.21), which catalyzes the first committed step in the formation of cholesterol/ergosterol. The degradation of Tat2p was dependent on the Rsp5p-mediated ubiquitination of Tat2p and was not suppressed by deletions of VPS1, VPS27, VPS45 or PEP12. We will discuss ZA-mediated Tat2p degradation in the context of lipid rafts. PMID:17531951

  11. Abiotic Degradation Rates for Carbon Tetrachloride: and Chloroform: Progress in FY 2008

    SciTech Connect

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

    2008-10-31

    This is a letter report summarizing work performed in FY2008 to determine the rates of carbon tetrachloride hydrolysis at temperatures close to actual groundwater temperatures. The report describes the project, the methodology, and the results obtained since the project's inception in FY2006. Measurements of hydrolysis rates in homogeneous solution have been completed for temperaturs of 70 C through 40 C, with additional data available at 30 C and 20 C. These results show no difference between the rates in deionized H2O and in filter-sterilized Hanford-Site groundwater. Moreover, the rates measured are 2-3 times slower than predicted from the open literature. Measurements of rates involving sterile suspensions of Hanford-Site sediment in Hanford-Site groundwater, however, show faster hydrolysis at temperatures below 40 C. Extrapolation of the current data available suggests a six-fold increase in rate would be expected at groundwater temperature of 16 C due to the presence of the sediment. This result translates into a 78-year half-life, rather than the 470-680 year half-life that would be predicted from rate determinations in homogeneous solution. The hydrolysis rate data at 20 C, in contrast to those at higher temperatures, are preliminary and have low statistical power. While significant (p < 0.05) differences between the heterogeneous and homogeneous systems are seen at 30 C, the results at 20 C are not statistically significant at this level due to limited data and the very slow nature of the reaction. More time is needed to collect data at these low temperatures to improve the statistical power of our observation. Given the critical need for hydrolysis rate data at temperatures relevant to groundwater systems, we have three recommendations for future work. First, we recommend a continuation of the sampling and analysis of the remaining long-term sealed-ampule experiments described in this report. These are primarily 20 C and 30 C experiments. The data at 20

  12. Comparing Background and Recent Erosion Rates in Degraded Areas of Southeastern Brazil

    NASA Astrophysics Data System (ADS)

    Fernandes, N.; Bierman, P. R.; Sosa-Gonzalez, V.; Rood, D. H.; Fontes, R. L.; Santos, A. C.; Godoy, J. M.; Bhering, S.

    2014-12-01

    Soil erosion is a major problem in northwestern Rio de Janeiro State where, during the last three centuries, major land-use changes took place, associated with the replacement of the original rainforest by agriculture and grazing. The combination of steep hillslopes, erodible soils, sparse vegetation, natural and human-induced fires, as well as downslope ploughing, led to an increase in surface runoff and surface erosion on soil-mantled hillslopes; together, these actions and responses caused a decline in soil productivity. In order to estimate changes in erosion rates over time, we compared erosion rates measured at different spatial and temporal scales, both background (natural) and short-term (human-induced during last few decades). Background long-term erosion rates were measured using in-situ produced cosmogenic 10Be in the sand fraction quartz of active river channel sediment in four basins in the northwestern portion of Rio de Janeiro State. In these basins, average annual precipitation varies from 1,200 to 1,300 mm, while drainage areas vary from 15 to 7,200 km2. Short-term erosion rates were measured in one of these basins from fallout 210Pb in soil samples collected along a hillslope transect located in an abandoned agriculture field. In this transect, 190 undisturbed soil samples (three replicates) were collected from the surface to 0.50 m depth (5 cm vertical intervals) in six soil pits. 10Be average background, basin-wide, erosion rates in the area are ~ 13 m/My; over the last decades, time-integrated (210Pb) average hillslope erosion rates are around 1450 m/Myr, with maximum values at the steepest portion of convex hillslopes of about 2000 m/Myr. These results suggest that recent hillslope erosion rates are about 2 orders of magnitude above background rates of sediment generation integrated over many millennia. This unsustainable rate of soil loss has severely decreased soil productivity eventually leading to the abandonment of farming activities in

  13. SLIRP Regulates the Rate of Mitochondrial Protein Synthesis and Protects LRPPRC from Degradation.

    PubMed

    Lagouge, Marie; Mourier, Arnaud; Lee, Hyun Ju; Spåhr, Henrik; Wai, Timothy; Kukat, Christian; Silva Ramos, Eduardo; Motori, Elisa; Busch, Jakob D; Siira, Stefan; Kremmer, Elisabeth; Filipovska, Aleksandra; Larsson, Nils-Göran

    2015-08-01

    We have studied the in vivo role of SLIRP in regulation of mitochondrial DNA (mtDNA) gene expression and show here that it stabilizes its interacting partner protein LRPPRC by protecting it from degradation. Although SLIRP is completely dependent on LRPPRC for its stability, reduced levels of LRPPRC persist in the absence of SLIRP in vivo. Surprisingly, Slirp knockout mice are apparently healthy and only display a minor weight loss, despite a 50-70% reduction in the steady-state levels of mtDNA-encoded mRNAs. In contrast to LRPPRC, SLIRP is dispensable for polyadenylation of mtDNA-encoded mRNAs. Instead, deep RNA sequencing (RNAseq) of mitochondrial ribosomal fractions and additional molecular analyses show that SLIRP is required for proper association of mRNAs to the mitochondrial ribosome and efficient translation. Our findings thus establish distinct functions for SLIRP and LRPPRC within the LRPPRC-SLIRP complex, with a novel role for SLIRP in mitochondrial translation. Very surprisingly, our results also demonstrate that mammalian mitochondria have a great excess of transcripts under basal physiological conditions in vivo. PMID:26247782

  14. SLIRP Regulates the Rate of Mitochondrial Protein Synthesis and Protects LRPPRC from Degradation

    PubMed Central

    Lagouge, Marie; Mourier, Arnaud; Lee, Hyun Ju; Spåhr, Henrik; Wai, Timothy; Kukat, Christian; Silva Ramos, Eduardo; Motori, Elisa; Busch, Jakob D.; Siira, Stefan; Kremmer, Elisabeth; Filipovska, Aleksandra; Larsson, Nils-Göran

    2015-01-01

    We have studied the in vivo role of SLIRP in regulation of mitochondrial DNA (mtDNA) gene expression and show here that it stabilizes its interacting partner protein LRPPRC by protecting it from degradation. Although SLIRP is completely dependent on LRPPRC for its stability, reduced levels of LRPPRC persist in the absence of SLIRP in vivo. Surprisingly, Slirp knockout mice are apparently healthy and only display a minor weight loss, despite a 50–70% reduction in the steady-state levels of mtDNA-encoded mRNAs. In contrast to LRPPRC, SLIRP is dispensable for polyadenylation of mtDNA-encoded mRNAs. Instead, deep RNA sequencing (RNAseq) of mitochondrial ribosomal fractions and additional molecular analyses show that SLIRP is required for proper association of mRNAs to the mitochondrial ribosome and efficient translation. Our findings thus establish distinct functions for SLIRP and LRPPRC within the LRPPRC-SLIRP complex, with a novel role for SLIRP in mitochondrial translation. Very surprisingly, our results also demonstrate that mammalian mitochondria have a great excess of transcripts under basal physiological conditions in vivo. PMID:26247782

  15. Enantioselective Metabolism of Chiral 3-Phenylbutyric Acid, an Intermediate of Linear Alkylbenzene Degradation, by Rhodococcus rhodochrous PB1

    PubMed Central

    Simoni, S.; Klinke, S.; Zipper, C.; Angst, W.; Kohler, H. E.

    1996-01-01

    Rhodococcus rhodochrous PB1 was isolated from compost soil by selective culture with racemic 3-phenylbutyric acid as the sole carbon and energy source. Growth experiments with the single pure enantiomers as well as with the racemate showed that only one of the two enantiomers, (R)-3-phenylbutyric acid, supported growth of strain PB1. Nevertheless, (S)-3-phenylbutyric acid was cometabolically transformed to, presumably, (S)-3-(2,3-dihydroxyphenyl)butyric acid (the absolute configuration at the C-3 atom is not known yet) by (R)-3-phenylbutyric acid-grown cells of strain PB1, as shown by (sup1)H nuclear magnetic resonance spectroscopy of the partially purified compound and gas chromatography-mass spectrometry analysis of the trimethylsilyl derivative. Oxygen uptake rates suggest that either 3-phenylpropionic acid or cinnamic acid (trans-3-phenyl-2-propenoic acid) is the substrate for aromatic ring hydroxylation. This view is substantiated by the fact that 3-(2,3-dihydroxyphenyl)propionic acid was a substrate for meta cleavage in cell extracts of (R)-3-phenylbutyric acid-grown cells of strain PB1. Gas chromatography-mass spectrometry analysis of trimethylsilane-treated ethyl acetate extracts of incubation mixtures showed that both the meta-cleavage product, 2-hydroxy-6-oxo-2,4-nonadiene-1,9-dicarboxylic acid, and succinate, a hydrolysis product thereof, were formed during such incubations. PMID:16535265

  16. Burn rates of pristine and degraded explosives at elevated temperatures and pressures

    SciTech Connect

    Chandler, J B; Maienschein, J L

    1998-08-10

    We measure the Laminar burn rates of explosives at extreme conditions (up to 520K and 1 GPa) in a hybrid strand burner, to provide reaction rate data for prediction of violence of thermal response. Data from a series of HMX-based explosives show that explosives with high binder content (15 wt%) burn smoothly over the entire pressure range regardless of particle size, while explosives with less binder eventually transition to a rapid erratic burn 10-100 times faster. When heated to ~ 440K, an HMX formulation with fine particles and 15% binder exhibits different burning behav- ior depending on the details of the temperature-pressure history, apparently as a result of the {beta} {yields} {delta} phase transition in HMX. Burn rates can be increased by 1000-fold under certain conditions.

  17. Long-term degradation study of hyaluronic acid in aqueous solutions without protection against microorganisms.

    PubMed

    Simulescu, Vasile; Kalina, Michal; Mondek, Jakub; Pekař, Miloslav

    2016-02-10

    The degradation of hyaluronan (HA) of different molecular weights (Mw 14.3, 267.2 and 1160.6 kDa, measured for fresh solutions, before degradation) was studied in aqueous solutions by SEC-MALLS determination of molecular mass, polydispersity and conformation parameters. The solutions were stored either at laboratory or refrigerator temperatures for two months. After this period the weight average molecular weight decreased by 90% for 14.3 kDa, 95% for 267.2 kDa and 71% for 1160.6 kDa hyaluronan (room temperature) or 5.6% for 14.3 kDa, 6.2% for 267.2 kDa and 7.7% for 1160.6 kDa hyaluronan (refrigerator temperature). The hyaluronan aqueous solutions studied did not contain sodium azide or other protectants against microorganisms, because the aim of our study was to assess the degradation in solutions to be used in medicine or cosmetics (without any compounds that are poisonous or toxic for the human body). The solvent used to prepare the samples was pure water. The polydispersity of all the samples remained unaltered during the entire degradation at both temperatures. This indicates a non-random mechanism of degradation. PMID:26686177

  18. Engineering hyaluronic acid hydrogel degradation to control cellular interactions and adult stem cell fate in 3D

    NASA Astrophysics Data System (ADS)

    Khetan, Sudhir

    The design and implementation of extracellular matrix (ECM)-mimetic hydrogels for tissue engineering (TE) applications requires an intensive understanding of cell-material interactions, including matrix remodeling and stem cell differentiation. However, the influence of microenvironmental cues, e.g., matrix biodegradability, on cell behavior in vitro has not been well studied in the case of direct cell encapsulation within 3-dimensional (3D) hydrogels. To address these issues, a facile sequential crosslinking technique was developed that provides spatial and temporal control of 3D hydrogel degradability to investigate the importance of material design on cell behavior. Specifically, hydrogels were synthesized from hyaluronic acid (HA) macromers in a sequential process: (1) a primary Michael-type addition crosslinking using cell adhesive and matrix metalloprotease (MMP)-degradable oligopeptides to consume a portion of total reactive groups and resulting in "-UV" hydrogels permissive to cell-mediated degradation, followed by (2) a secondary, light initiated free-radical crosslinking to consume remaining reactive groups and "switch" the network to a non-degradable structure ("+UV") via the addition of non-degradable kinetic chains. Using this approach, we demonstrated control of encapsulated hMSC spreading by varying the crosslink type (i.e., the relative hydrogel biodegradability), including with spatial control. Upon incubation with bipotential soluble differentiation factors, these same degradation-mediated spreading cues resulted in an hMSC differentiation fate switch within -UV versus +UV environments. Follow-up studies demonstrated that degradation-mediated traction generation, rather than matrix mechanics or cell morphology, is the critical biophysical signal determining hMSC fate. Sequentially crosslinked HA hydrogels were also studied for the capacity to support remodeling by in vivo and ex vivo tissues, including with spatial control, toward tissue

  19. The degradation of airway tight junction protein under acidic conditions is probably mediated by transient receptor potential vanilloid 1 receptor

    PubMed Central

    Xu, Rui; Li, Qi; Zhou, Jia; Zhou, Xiang-dong; Perelman, Juliy M.; Kolosov, Victor P.

    2013-01-01

    Acidic airway microenvironment is one of the representative pathophysiological features of chronic inflammatory respiratory diseases. Epithelial barrier function is maintained by TJs (tight junctions), which act as the first physical barrier against the inhaled substances and pathogens of airway. As previous studies described, acid stress caused impaired epithelial barriers and led the hyperpermeability of epithelium. However, the specific mechanism is still unclear. We have showed previously the existence of TRPV (transient receptor potential vanilloid) 1 channel in airway epithelium, as well as its activation by acidic stress in 16HBE cells. In this study, we explored the acidic stress on airway barrier function and TJ proteins in vitro with 16HBE cell lines. Airway epithelial barrier function was determined by measuring by TER (trans-epithelial electrical resistance). TJ-related protein [claudin-1, claudin-3, claudin-4, claudin-5, claudin-7 and ZO-1 (zonula occluden 1)] expression was examined by western blotting of insoluble fractions of cell extraction. The localization of TJ proteins were visualized by immunofluorescent staining. Interestingly, stimulation by pH 6.0 for 8 h slightly increased the epithelial resistance in 16HBE cells insignificantly. However, higher concentration of hydrochloric acid (lower than pH 5.0) did reduce the airway epithelial TER of 16HBE cells. The decline of epithelial barrier function induced by acidic stress exhibited a TRPV1-[Ca2+]i-dependent pathway. Of the TJ proteins, claudin-3 and claudin-4 seemed to be sensitive to acidic stress. The degradation of claudin-3 and claudin-4 induced by acidic stress could be attenuated by the specific TRPV1 blocker or intracellular Ca2+ chelator BAPTA/AM [1,2-bis-(o-aminophenoxy)ethane-N,N,N',N'-tetra-acetic acid tetrakis(acetoxymethyl ester)]. PMID:24073800

  20. Fumigant degradation as affected by different application rate in five soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil fumigation is critical in controlling soil-borne pests and diseases and ensuring high yields for many crops. The excellent performance of the totally impermeable film (TIF) on fumigant emission control and pest control efficacy made it possible to use reduced fumigation rates under the tarp to ...

  1. Phytoremediation potential of duckweed (Lemna minor L.) in degradation of C.I. Acid Blue 92: artificial neural network modeling.

    PubMed

    Khataee, A R; Movafeghi, A; Torbati, S; Salehi Lisar, S Y; Zarei, M

    2012-06-01

    In present study, the potential of duckweed (Lemna minor L.) for degradation of an azo dye C.I. Acid Blue 92 (AB92) has been investigated. The effect of operational parameters such as initial dye concentration, pH, temperature and amount of plant on the efficiency of biological decolorization process was determined. The reusability of Lemna minor L. in long term repetitive operations was also examined. Growth and some biochemical parameters (photosynthetic pigments content, superoxide dismutase, catalase and peroxidase activity) were used to detect the toxic effects of AB92 on duckweed plant. The biological degradation compounds formed in the present process were analyzed by GC-MS technique. In addition, an artificial neural network (ANN) model was expanded to predict the biological decolorization efficiency. The obtained data indicated that ANN provide realistic predictive performance (R(2)=0.954). PMID:22498423

  2. Hydrolysis rates, methane production and nitrogen solubilisation of grey waste components during anaerobic degradation.

    PubMed

    Jokela, J P Y; Vavilin, V A; Rintala, J A

    2005-03-01

    Municipal grey waste (i.e. the remaining fraction in municipal waste management systems in which putrescibles (biowaste) and other recyclables (paper, metals, glass) are source-segregated) was manually sorted into six main fractions on the basis of composition and also separated by sieving (100 mm mesh size) into two fractions, oversized and undersized, respectively. In practice, in waste management plant the oversized fraction is (or will be) used to produce refuse-derived fuel and the undersized landfilled after biological stabilisation. The methane yields and nitrogen solubilisation of the grey waste and the different fractions (all studied samples were first milled to 5 mm particle samples) were determined in a 237-day methane production batch assay and in a water elution test, respectively. The grey waste was found to contained remnants of putrescibles and also a high amount of other biodegradable waste, including packaging, cartons and cardboard, newsprint, textiles and diapers. These waste fractions comprised 41%-w/w of the grey waste and produced 40-210 m3 methane (total solids (TS))(-1) and less than 0.01 g NH4-N kg TS(added)(-1) except diapers which produced 9.8 g NH4-N kg TS(added)(-1) in the batch assays. In the case of the two sieved fractions and on mass bases, most of the methane originated from the oversized fraction, whereas most of the NH4-N was solublised from the undersized fraction. The first-order kinetic model described rather well the degradation of each grey waste fraction and component, showing the different components to be in the range 0.021-0.058 d(-1), which was around one-sixth of the values reported for the source-segregated putrescible fraction of MSW. PMID:15491833

  3. Elucidating the Pseudomonas aeruginosa fatty acid degradation pathway: identification of additional fatty acyl-CoA synthetase homologues.

    PubMed

    Zarzycki-Siek, Jan; Norris, Michael H; Kang, Yun; Sun, Zhenxin; Bluhm, Andrew P; McMillan, Ian A; Hoang, Tung T

    2013-01-01

    The fatty acid (FA) degradation pathway of Pseudomonas aeruginosa, an opportunistic pathogen, was recently shown to be involved in nutrient acquisition during BALB/c mouse lung infection model. The source of FA in the lung is believed to be phosphatidylcholine, the major component of lung surfactant. Previous research indicated that P. aeruginosa has more than two fatty acyl-CoA synthetase genes (fadD; PA3299 and PA3300), which are responsible for activation of FAs using ATP and coenzyme A. Through a bioinformatics approach, 11 candidate genes were identified by their homology to the Escherichia coli FadD in the present study. Four new homologues of fadD (PA1617, PA2893, PA3860, and PA3924) were functionally confirmed by their ability to complement the E. coli fadD mutant on FA-containing media. Growth phenotypes of 17 combinatorial fadD mutants on different FAs, as sole carbon sources, indicated that the four new fadD homologues are involved in FA degradation, bringing the total number of P. aeruginosa fadD genes to six. Of the four new homologues, fadD4 (PA1617) contributed the most to the degradation of different chain length FAs. Growth patterns of various fadD mutants on plant-based perfumery substances, citronellic and geranic acids, as sole carbon and energy sources indicated that fadD4 is also involved in the degradation of these plant-derived compounds. A decrease in fitness of the sextuple fadD mutant, relative to the ΔfadD1D2 mutant, was only observed during BALB/c mouse lung infection at 24 h. PMID:23737986

  4. Ligand-functionalized degradable polyplexes formed by cationic poly(aspartic acid)-grafted chitosan-cyclodextrin conjugates.

    PubMed

    Song, Hai-Qing; Li, Rui-Quan; Duan, Shun; Yu, Bingran; Zhao, Hong; Chen, Da-Fu; Xu, Fu-Jian

    2015-03-19

    Polypeptide-based degradable polyplexes attracted considerable attention in drug delivery systems. Polysaccharides including cyclodextrin (CD), dextran, and chitosan (CS) were readily grafted with cationic poly(aspartic acid)s (PAsps). To further enhance the transfection performances of PAsp-based polyplexes, herein, different types of ligand (folic acid, FA)-functionalized degradable polyplexes were proposed based on the PAsp-grafted chitosan-cyclodextrin conjugate (CCPE), where multiple β-CDs were tied on a CS chain. The FA-functionalized CCPE (i.e., CCPE-FA) was obtained via a host-guest interaction between the CD units of CCPE and the adamantane (Ad) species of Ad-modified FA (Ad-FA). The resulting CCPE/pDNA, CCPE-FA/pDNA, and ternary CCPE-FA/CCPE/pDNA (prepared by layer-by-layer assembly) polyplexes were investigated in detail using different cell lines. The CCPE-based polyplexes displayed much higher transfection efficiencies than the CS-based polyplexes reported earlier by us. The ternary polyplexes of CCPE-FA/CCPE/pDNA produced excellent gene transfection abilities in the folate receptor (FR)-positive tumor cells. This work would provide a promising means to produce highly efficient polyplexes for future gene therapy applications. PMID:25758351

  5. Fabrication of ZnFe2O4 films and its application in photoelectrocatalytic degradation of salicylic acid.

    PubMed

    Kumbhar, S S; Mahadik, M A; Shinde, S S; Rajpure, K Y; Bhosale, C H

    2015-01-01

    ZnFe2O4 thin films are successfully deposited onto bare and fluorine doped tin oxide (FTO) coated quartz substrate using the spray pyrolysis method. The structure and morphology of ZnFe2O4 photoelectrodes were studied by X-ray diffraction (XRD) and atomic force microscopy (AFM). The X-ray diffraction pattern confirms the polycrystalline nature of films with a spinel cubic crystal structure. The AFM micrographs shows the granular nature of the films. The dielectric constant and dielectric loss shows dispersion behavior as a function of frequency measured in the range from 20Hz to 1MHz. Photoelectrocatalysis degradation of salicylic acid using ZnFe2O4 photoelectrode under sunlight illumination has been investigated. The result shows that the degradation percentage of salicylic acid on ZnFe2O4 photoelectrodes is reached 49% under neutral conditions after 320min illumination. The decrease in values of COD from 19.4mg/L to 6.4mg/L indicates there is mineralization of salicylic acid with time. PMID:25528302

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

    SciTech Connect

    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.

  7. BenR, a XylS Homologue, Regulates Three Different Pathways of Aromatic Acid Degradation in Pseudomonas putida

    PubMed Central

    Cowles, Charles E.; Nichols, Nancy N.; Harwood, Caroline S.

    2000-01-01

    Pseudomonas putida converts benzoate to catechol using two enzymes that are encoded on the chromosome and whose expression is induced by benzoate. Benzoate also binds to the regulator XylS to induce expression of the TOL (toluene degradation) plasmid-encoded meta pathway operon for benzoate and methylbenzoate degradation. Finally, benzoate represses the ability of P. putida to transport 4-hydroxybenzoate (4-HBA) by preventing transcription of pcaK, the gene encoding the 4-HBA permease. Here we identified a gene, benR, as a regulator of benzoate, methylbenzoate, and 4-HBA degradation genes. A benR mutant isolated by random transposon mutagenesis was unable to grow on benzoate. The deduced amino acid sequence of BenR showed high similarity (62% identity) to the sequence of XylS, a member of the AraC family of regulators. An additional seven genes located adjacent to benR were inferred to be involved in benzoate degradation based on their deduced amino acid sequences. The benABC genes likely encode benzoate dioxygenase, and benD likely encodes 2-hydro-1,2-dihydroxybenzoate dehydrogenase. benK and benF were assigned functions as a benzoate permease and porin, respectively. The possible function of a final gene, benE, is not known. benR activated expression of a benA-lacZ reporter fusion in response to benzoate. It also activated expression of a meta cleavage operon promoter-lacZ fusion inserted in an E. coli chromosome. Third, benR was required for benzoate-mediated repression of pcaK-lacZ fusion expression. The benA promoter region contains a direct repeat sequence that matches the XylS binding site previously defined for the meta cleavage operon promoter. It is likely that BenR binds to the promoter region of chromosomal benzoate degradation genes and plasmid-encoded methylbenzoate degradation genes to activate gene expression in response to benzoate. The action of BenR in repressing 4-HBA uptake is probably indirect. PMID:11053377

  8. In vitro degradation and in vivo biocompatibility of poly(lactic acid) mesh for soft tissue reinforcement in vaginal surgery.

    PubMed