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Sample records for phenoxy acid degradation

  1. 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

  2. Bacterial degradation of phenoxy herbicide mixtures 2,4-D and MCPP

    SciTech Connect

    Kyeheon Oh; Tuovinen, O.H. )

    1991-08-01

    The phenoxy herbicides 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-(2-methyl-4-chlorophenoxy)propionic acid (MCPP) have auxin-like growth regulating properties and are extensively used for the control of broad-leaf angiosperm weeds. The microbiological degradation of 2,4-D by pure and mixed cultures has been examined in a number of studies. The authors have previously evaluated the concurrent microbiological degradation of 2,4-D and MCPP in stirred tank reactors. For the present paper, they examined the utilization of the two substrates by three mixed cultures that had a previous history of growth with the respective single phenoxy herbicide.

  3. Determination of phenoxy acid herbicides in water by electron-capture and microcoulometric gas chromatography

    USGS Publications Warehouse

    Goerlitz, D.F.; Lamar, William L.

    1967-01-01

    A sensitive gas chromatographic method using microcoulometric titration and electron-capture detection for the analysis of 2,4-D, silvex, 2,4,5-T, and other phenoxy acid herbicides in water is described. The herbicides are extracted from unfiltered water samples (800-1,000 ml) by use of ethyl ether ; then the herbicides are concentrated and esterilied. To allow the analyst a choice, two esterilication procedures--using either boron trifluoride-methanol or diazomethane--are evaluated. Microcoulometric gas chromatography is specific for the detection of halogenated compounds such as the phenoxy acid herbicides whereas it does not respond to nonhalogenated components. Microcoulometric gas chromatography requires care and patience. It is not convenient for rapid screening of l-liter samples that contain less than 1 microgram of the herbicide. Although electroncapture gas chromatography is less selective and more critically affected by interfering substances, it is, nevertheless, convenient and more sensitive than microcoulometric gas chromatography. Two different liquid phases are used in the gas chromatographic columns--DC-200 silicone in one column and QF-1 silicone in the other. The performance of both columns is improved by the addition of Carbowax 20M. The Gas Chrom Q support is coated with the liquid phases by the 'frontal-analysis' technique. The practical lower limits for measurement of the phenoxy acid herbicides in water primarily depend upon the sample size, interferences present, anal instrumentation used. With l-liter samples of water, the practical lower limits of measurement are 10 ppt (parts per trillion) for 2,4-D and 2 ppt for silvex and 2,4,5-T when electron-capture detection is used, and approximately 20 ppt for each herbicide when analyzed by microcoulometric-titration gas chromatography. Recoveries of the herbicides immediately after addition to unfiltered water samples averaged 92 percent for 2,4-D, 90 percent for silvex, and 98 percent for 2

  4. TRACE ANALYSIS OF FLUORESCEIN-DERIVATIZED PHENOXY ACID HERBICIDES BY MICELLAR ELECTROKINETIC CHROMATOGRAPHY WITH LASER-INDUCTED FLUORESCENCE DETECTION

    EPA Science Inventory

    Micellar electrokinetic chromatography (MEKC) with laser-induced fluorescence (LIF) detection was used for the trace analysis of phenoxy acid herbicides. Capillary electrophoresis (CE) with LIF detection, which has not previously been used for pesticide analysis, overcomes the po...

  5. DFT computation and experimental analysis of vibrational and electronic spectra of phenoxy acetic acid herbicides

    NASA Astrophysics Data System (ADS)

    Arul Dhas, D.; Hubert Joe, I.; Roy, S. D. D.; Balachandran, S.

    2013-05-01

    An absolute vibrational analysis has been attempted on the basis of experimental FTIR and NIR-FT Raman spectra with calculated vibrational wavenumbers and intensities of phenoxy acetic acids. The equilibrium geometry, bonding features and harmonic vibrational wavenumbers have been calculated with the help of B3LYP method with Dunning correlation consistent basis set aug-cc-pVTZ. The electronic structures of molecular fragments were described in terms of natural bond orbital analysis, which shows intermolecular Osbnd H⋯O and intramolecular Csbnd H⋯O hydrogen bonds. The electronic absorption spectra with different solvents have been investigated in combination with time-dependent density functional theory calculation. The pKa values of phenoxy acetic acids were compared.

  6. Malignant lymphoma and exposure to chemicals, especially organic solvents, chlorophenols and phenoxy acids: a case-control study.

    PubMed Central

    Hardell, L.; Eriksson, M.; Lenner, P.; Lundgren, E.

    1981-01-01

    A number of men with malignant lymphoma of the histiocytic type and previous exposure to phenoxy acids or chlorophenols were observed and reported in 1979. A matched case-control study has therefore been performed with cases of malignant lymphoma (Hodgkin's disease and non-Hodgkin lymphoma). This study included 169 cases and 338 controls. The results indicate that exposure to phenoxy acids, chlorophenols, and organic solvents may be a causative factor in malignant lymphoma. Combined exposure of these chemicals seemed to increase the risk. Exposure to various other agents was not obviously different in cases and in controls. PMID:7470379

  7. A review of methods for the analysis of orphan and difficult pesticides: glyphosate, glufosinate, quaternary ammonium and phenoxy acid herbicides, and dithiocarbamate and phthalimide fungicides.

    PubMed

    Raina-Fulton, Renata

    2014-01-01

    This article reviews the chromatography/MS methodologies for analysis of pesticide residues of orphan and difficult chemical classes in a variety of sample matrixes including water, urine, blood, and food. The review focuses on pesticide classes that are not commonly included in multiresidue analysis methods such as highly polar or ionic herbicides including glyphosate, glufosinate, quaternary ammonium, and phenoxy acid herbicides, and some of their major degradation or metabolite products. In addition, dithiocarbamate and phthalimide fungicides, which are thermally unstable and have stability issues in some solvents or sample matrixes, are also examined due to their special needs in residue analysis. PMID:25145125

  8. FT IR, FT-Raman spectra and chemical computations of herbicide 2-phenoxy propionic acid - A DFT approach

    NASA Astrophysics Data System (ADS)

    Joselin Beaula, T.; James, C.

    2014-03-01

    FT IR and FT Raman spectra of herbicidal molecule 2-phenoxy propionic acid have been recorded and analyzed with the aid of normal coordinate analysis and DFT methods. Stability of the molecule arising from hyperconjugative interactions has been probed using NBO analysis. Predicted electronic absorption spectrum from TD-DFT calculation has been compared with the UV-vis spectrum. HOMO-LUMO, Mulliken population analysis and atomic charges, thermodynamic calculation and aromaticity were also calculated. From the PES scan the most stable geometry has been determined. ESP has been mapped over the electron density to obtain information about the size, shape, charge density distribution and chemical reactivity of the molecule.

  9. Evaluation of exposure to organophosphate, carbamate, phenoxy acid, and chlorophenol pesticides in pregnant women from 10 Caribbean countries.

    PubMed

    Forde, Martin S; Robertson, Lyndon; Laouan Sidi, Elhadji A; Côté, Suzanne; Gaudreau, Eric; Drescher, Olivia; Ayotte, Pierre

    2015-09-01

    Pesticides are commonly used in tropical regions such as the Caribbean for both household and agricultural purposes. Of particular concern is exposure during pregnancy, as these compounds can cross the placental barrier and interfere with fetal development. The objective of this study was to evaluate exposure of pregnant women residing in 10 Caribbean countries to the following commonly used classes of pesticides in the Caribbean: organophosphates (OPs), carbamates, phenoxy acids, and chlorophenols. Out of 438 urine samples collected, 15 samples were randomly selected from each Caribbean country giving a total of 150 samples. Samples were analyzed for the following metabolites: six OP dialkylphosphate metabolites [dimethylphosphate (DMP), dimethylthiophosphate (DMTP), dimethyldithiophosphate (DMDTP), diethylphosphate (DEP), diethylthiophosphate (DETP) and diethyldithiophosphate (DEDTP)]; two carbamate metabolites [2-isopropoxyphenol (2-IPP) and carbofuranphenol]; one phenoxy acid 2,4-dichlorophenoxyacetic acid (2,4-D); and five chlorophenols [2,4-dichlorophenol (DCP), 2,5-dichlorophenol (2,5-DCP), 2,4,5-trichlorophenol (TCP), 2,4,6-trichlorophenol (2,4,6-TCP), and pentachlorophenol (PCP)]. OP metabolites were consistently detected in ≥60% of the samples from Antigua and Barbuda, Bermuda, and Jamaica. Of the carbamate metabolites, 2-IPP was detected in seven of the 10 Caribbean countries with a detection frequency around 30%, whereas carbofuranphenol was detected in only one sample. The detection frequency for the phenoxy acid 2,4-D ranged from 20% in Grenada to a maximum of 67% in Belize. Evidence of exposure to chlorophenol pesticides was also established with 2,4-DCP by geometric means ranging from 0.52 μg L(-1) in St Lucia to a maximum of 1.68 μg L(-1) in Bermuda. Several extreme concentrations of 2,5-DCP were detected in four Caribbean countries-Belize (1100 μg L(-1)), Bermuda (870 μg L(-1)), Jamaica (1300 μg L(-1)), and St Kitts and Nevis (1400 μg L(-1

  10. Fast determination of phenoxy acid herbicides in carrots and apples using liquid chromatography coupled triple quadrupole mass spectrometry.

    PubMed

    Santilio, Angela; Stefanelli, Patrizia; Dommarco, Roberto

    2009-08-01

    A fast, simple and inexpensive method has been developed for the analysis of phenoxy acid herbicides: 2,4-dichlorophenoxyacetic acid (2,4-D), 4-chloro-2-methylphenoxyacetic acid (MCPA), 2-(4-chloro-o-tolyloxy)propionic acid (MCPP), 2-(4-aryloxyphenoxy)propionic acid (Fluazifop) and 2-(4-aryloxyphenoxy)propionic acid (Haloxyfop) in carrots and apples by liquid chromatography coupled to triple quadrupole mass spectrometry (LC/MS/MS). The compounds were analyzed by QuEChERS (quick, easy, cheap, effective, rugged, safe) methodology without cleanup. The recoveries were performed at two spiked levels (0.05 and 0.5 mg/kg) for both matrices with six replicates for each level. The mean recoveries ranged from 70-92% for both apples and carrots. The precision of the method expressed as relative standard deviation (RSD%) was found to be in the range 3-15%. For all compounds, good linearity (r(2) > 0.99) was obtained over the range of concentration from 0.05 micro g/mL to 0.5 micro g/mL, corresponding to the pesticide concentrations of 0.05 mg/kg and 0.5 mg/kg, respectively. The determination limits (LOQs) ranged from 0.01 ng/mL to 1.3 ng/mL in solvent, whereas, the LOQs calculated in matrix ranged from 0.05 ng/g to 21.0 ng/g for apples and from 0.06 ng/g to 10.2 ng/g for carrots. The developed methodology combines the advantages of both QuEChERS and LC/MS/MS producing a very rapid, sensitive and cheap method useful for the routine analytical laboratories. PMID:20183066

  11. Passive extraction and clean-up of phenoxy acid herbicides in samples from a groundwater plume using hollow fiber supported liquid membranes.

    PubMed

    Liu, Jing-Fu; Toräng, Lars; Mayer, Philipp; Jönsson, Jan Ake

    2007-08-10

    Hollow fiber supported liquid membranes were applied for the passive extraction of phenoxy acid herbicides from water samples. Polypropylene hollow fiber membranes (240 microm i.d., 30 microm wall thickness, 0.05 microm pore size, 30 cm length) were impregnated with 2.0% tri-n-octylphosphine oxide (TOPO) in di-n-hexyl ether in the pores of the fiber wall to form a liquid membrane. They were then filled with basic solution in the lumen as acceptor and finally placed into the sample (donor). Complete extraction of phenoxy acid herbicides including 2,4-D, MCPA, dichlorprop, and mecoprop from an acidified sample (4 mL, adjusted to pH 1.5 with HCl) into basic acceptor (10 microL of 0.2M NaOH) was achieved after 4 h of shaking (100 rpm) resulting in an enrichment factor of 400 times. The acceptor was then neutralized by addition of HCl and injected into a HPLC system for the determination of the phenoxy acid herbicides. Environmentally relevant salinity (0-3.5% NaCl) and dissolved organic matter (0-25 mg/L of dissolved organic carbon) had no significant effect on the extraction. The method provided extraction efficiencies of more than 91%, detection limits of 0.3-0.6 microg/L, and combined extraction and clean up in one single step. This procedure was applied to determine aqueous concentrations of phenoxy acid herbicides in groundwater samples collected from an old dumping site (Cheminova, Denmark) with detected concentrations up to 5800 microg/L. Although the samples were very dirty with large amounts of suspended particles, non-aqueous phase liquids (NAPLs) and dissolved organic matters, good spike recoveries (80-126%) were obtained for 10 of the 11 samples. PMID:17449052

  12. Synthesis of phenoxy ethers of methyl lesquerolate over solid acid catalysts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Lesquerolic acid is the primary fatty acid found in Lesquerella. The seeds are 33% oil of which about 55% is the 20 carbon unsaturated hydroxyl fatty acid, lesquerolic acid. A simple derivatization of this fatty acid could expand its potential as an industrial oil. We have used a heterogeneous Le...

  13. 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

  14. Effects of a salt of cholestyramine and 2-[4-(p-chlorobenzoyl)phenoxy]2-methyl propionic acid (alpha-1081) on biliary lipid secretion in rats.

    PubMed

    Aldini, R; Barbara, L; Benelli, A; Borzatta, V; Geminiani, S; Mascellani, G; Morselli, A; Roda, A; Roda, E

    1981-11-01

    1 Hypolipidaemic agents may increase biliary cholesterol in man, inducing a supersaturated bile. 2 To evaluate this possible side-effect, we have studied bile lipid secretion over a period of 8 h with intact enterohepatic circulation and 4 h with complete interruption in rats treated for two months with a salt of cholestyramine and 2-[4-(p-chlorobenzoyl)-phenoxy]2-methyl propionic acid (alpha-1081, 1.150 g/kg body wt., daily), cholestyramine (1.125 g/kg body wt. daily), procetofenic acid (25 mg/kg body wt. daily) and saline respectively (six rats for each group). 3 Cholesterol saturation index significantly (P less than 0.005) increased (from 0.21 +/- 0.01 to 0.39 +/- 0.09, mean +/- s.d.), in rats fed with procetofenic acid but it did not in alpha-1081- and cholestyramine-treated animals. 4 Procetofenic acid and, to a lesser extent, cholestyramine increased the bile flow. Procetofenic acid increased cholesterol secretion from 0.45 +/- 0.17 to 0.94 +/- 0.19 mumol kg-1 body wt. h-1 (mean +/- s.d.). 5 Cholestyramine increased both serum cholesterol and bile acid secretion from 0.45 +/- 0.17 to 0.68 +/- 0.10 and 25.8 +/- 9.48 to 39.96 +/- 6.68 mumol kg-1 body wt. h-1 respectively; alpha-1081, on the contrary, had no effect on bile lipid secretion. 6 These data suggest that alpha-1081 may be used as a new hypolipidaemic drug without any risk of increasing cholesterol in bile. PMID:6895340

  15. Effects of a salt of cholestyramine and 2-[4-(p-chlorobenzoyl)phenoxy]2-methyl propionic acid (alpha-1081) on biliary lipid secretion in rats.

    PubMed Central

    Aldini, R.; Barbara, L.; Benelli, A.; Borzatta, V.; Geminiani, S.; Mascellani, G.; Morselli, A.; Roda, A.; Roda, E.

    1981-01-01

    1 Hypolipidaemic agents may increase biliary cholesterol in man, inducing a supersaturated bile. 2 To evaluate this possible side-effect, we have studied bile lipid secretion over a period of 8 h with intact enterohepatic circulation and 4 h with complete interruption in rats treated for two months with a salt of cholestyramine and 2-[4-(p-chlorobenzoyl)-phenoxy]2-methyl propionic acid (alpha-1081, 1.150 g/kg body wt., daily), cholestyramine (1.125 g/kg body wt. daily), procetofenic acid (25 mg/kg body wt. daily) and saline respectively (six rats for each group). 3 Cholesterol saturation index significantly (P less than 0.005) increased (from 0.21 +/- 0.01 to 0.39 +/- 0.09, mean +/- s.d.), in rats fed with procetofenic acid but it did not in alpha-1081- and cholestyramine-treated animals. 4 Procetofenic acid and, to a lesser extent, cholestyramine increased the bile flow. Procetofenic acid increased cholesterol secretion from 0.45 +/- 0.17 to 0.94 +/- 0.19 mumol kg-1 body wt. h-1 (mean +/- s.d.). 5 Cholestyramine increased both serum cholesterol and bile acid secretion from 0.45 +/- 0.17 to 0.68 +/- 0.10 and 25.8 +/- 9.48 to 39.96 +/- 6.68 mumol kg-1 body wt. h-1 respectively; alpha-1081, on the contrary, had no effect on bile lipid secretion. 6 These data suggest that alpha-1081 may be used as a new hypolipidaemic drug without any risk of increasing cholesterol in bile. PMID:6895340

  16. 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.

  17. 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

  18. Identification of a reactive degradation zone at a landfill leachate plume fringe using high resolution sampling and incubation techniques

    NASA Astrophysics Data System (ADS)

    Tuxen, Nina; Albrechtsen, Hans-Jørgen; Bjerg, Poul L.

    2006-05-01

    Vertical small-scale variation in phenoxy acid herbicide degradation across a landfill leachate plume fringe was studied using laboratory degradation experiments. Sediment cores (subdivided into 5 cm segments) were collected in the aquifer and the sediment and porewater were used for microcosm experiments (50 experiments) and for determination of solid organic carbon, solid-water partitioning coefficients, specific phenoxy acid degraders and porewater chemistry. Results from a multi-level sampler installed next to the cores provided information on the plume position and oxygen concentration in the groundwater. Oxygen concentration was controlled individually in each microcosm to mimic the conditions at their corresponding depths. A highly increased degradation potential existed at the narrow plume fringe (37.7 to 38.6 masl), governed by the presence of phenoxy acids and oxygen. This resulted in the proliferation of a microbial population of specific phenoxy acid degraders, which further enhanced the degradation potential for phenoxy acids at the fringe. The results illustrate the importance of fringe degradation processes in contaminant plumes. Furthermore, they highlight the relevance of using high-resolution sampling techniques as well as controlled microcosm experiments in the assessment of the natural attenuation capacity of contaminant plumes in groundwater.

  19. Phenoxy resins containing pendent ethynyl groups

    NASA Technical Reports Server (NTRS)

    Hergenrother, P. M.; Jensen, B. J.; Havens, S. J.

    1984-01-01

    As part of an effort on tougher/solvent resistant matrix resins for composites, research was directed towards exploring methods to improve the solvent resistance of linear amorphous thermoplastics. Ethyl reactive groups were placed on the ends of oligomers and pendent along the polymer chain and subsequently thermally reacted to provide crosslinking and thus improvement in solvent resistance. This concept is extended to another thermoplastic, a phenoxy resin. A commercially available phenoxy resin (PKHH) was systematically modified by reaction of the pendent hydroxyl groups on the phenoxy resin with various amounts of 4-ethynylbenzoyl chloride. As the pendent ethynyl group content in the phenoxy resin increased, the cured resin exhibited a higher glass transition temperature, better solvent resistance and less flexibility. The solvent resistance was further improved by correcting a low molecular weight diethynyl compound, 2,2-bis(4-ethynylbenzoyloxy-4'-phenyl)propane, with a phenoxy resin containing pendent ethynyl groups.

  20. 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.

  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. 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.

  8. Structure of substituted 2-(phenoxy)benzimidazoles

    NASA Astrophysics Data System (ADS)

    Pavlova, I. S.; Pervova, I. G.; Lipunova, G. N.; Novikova, R. K.; Slepukhin, P. A.; Lipunov, I. N.

    2013-03-01

    The synthesis and X-ray diffraction study of 1-benzyl-2-[2-(5-ethyltetrazole-2-yl)-phenoxy]-1H-benzimidazole and 1-benzyl-2-[2-(5-ethyltetrazole-2-yl)-4-nitrophenoxy]-1H-benzimidazole single crystals have been performed. The oxidative splitting of an azo-hydrazone group of 1-(2-hydroxy-(5-nitro)phenyl)-3-ethyl-5-(benzylbenzimidazolyl)formazans, a break in the C2-N1 bond, the interaction of o-hydroxyl group of aryl fragment with oxygen, and the formation of new 2-(phenoxy)benzimidazoles are found to occur in the presence of perchlorate iron(III).

  9. Structure of substituted 2-(phenoxy)benzimidazoles

    SciTech Connect

    Pavlova, I. S. Pervova, I. G.; Lipunova, G. N.; Novikova, R. K.; Slepukhin, P. A.; Lipunov, I. N.

    2013-03-15

    The synthesis and X-ray diffraction study of 1-benzyl-2-[2-(5-ethyltetrazole-2-yl)-phenoxy]-1H-benzimidazole and 1-benzyl-2-[2-(5-ethyltetrazole-2-yl)-4-nitrophenoxy]-1H-benzimidazole single crystals have been performed. The oxidative splitting of an azo-hydrazone group of 1-(2-hydroxy-(5-nitro)phenyl)-3-ethyl-5-(benzylbenzimidazolyl)formazans, a break in the C2-N1 bond, the interaction of o-hydroxyl group of aryl fragment with oxygen, and the formation of new 2-(phenoxy)benzimidazoles are found to occur in the presence of perchlorate iron(III).

  10. 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

  11. Substituted 2-[(4-aminomethyl)phenoxy]-2-methylpropionic acid PPARalpha agonists. 1. Discovery of a novel series of potent HDLc raising agents.

    PubMed

    Sierra, Michael L; Beneton, Véronique; Boullay, Anne-Bénédict; Boyer, Thierry; Brewster, Andrew G; Donche, Frédéric; Forest, Marie-Claire; Fouchet, Marie-Hélène; Gellibert, Françoise J; Grillot, Didier A; Lambert, Millard H; Laroze, Alain; Le Grumelec, Christelle; Linget, Jean Michel; Montana, Valerie G; Nguyen, Van-Loc; Nicodème, Edwige; Patel, Vipul; Penfornis, Annie; Pineau, Olivier; Pohin, Danig; Potvain, Florent; Poulain, Géraldine; Ruault, Cécile Bertho; Saunders, Michael; Toum, Jérôme; Xu, H Eric; Xu, Robert X; Pianetti, Pascal M

    2007-02-22

    The peroxisome proliferator activated receptors PPARalpha, PPARgamma, and PPARdelta are ligand-activated transcription factors that play a key role in lipid homeostasis. The fibrates raise circulating levels of high-density lipoprotein cholesterol and lower levels of triglycerides in part through their activity as PPARalpha agonists; however, the low potency and restricted selectivity of the fibrates may limit their efficacy, and it would be desirable to develop more potent and selective PPARalpha agonists. Modification of the selective PPARdelta agonist 1 (GW501516) so as to incorporate the 2-aryl-2-methylpropionic acid group of the fibrates led to a marked shift in potency and selectivity toward PPARalpha agonism. Optimization of the series gave 25a, which shows EC50 = 4 nM on PPARalpha and at least 500-fold selectivity versus PPARdelta and PPARgamma. Compound 25a (GW590735) has been progressed to clinical trials for the treatment of diseases of lipid imbalance. PMID:17243659

  12. [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

  13. [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

  14. 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

  15. 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.

  16. Permeability and corrosion behavior of phenoxy coatings

    SciTech Connect

    Tiburcio, A.C.; Manson, J.A.

    1993-12-31

    The corrosion behavior of a glass-bead-filled phenoxy coating system was studied by correlating permeability and electrochemical measurements with actual corrosion performance. The study emphasized the effects of filler and filler/polymer matrix interactions on corrosion behavior. Water vapor permeability, dissolved oxygen permeability and conductivity measurements were made to determine the rate of transport of the three key ingredients in cathodic delamination and corrosion process (H{sub 2}O, O{sub 2}, and cation). The glass bead filler had a greater effect on both cathodic delamination and corrosion behavior than filler/polymer matrix interaction. Overall, the permeability behavior controlled the delamination and corrosion performance.

  17. 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.

  18. Association between soft tissue sarcomas, malignant lymphomas, and phenoxy herbicides/chlorophenols: Evidence from occupational cohort studies

    SciTech Connect

    Johnson, E.S. )

    1990-02-01

    Some case-control studies have reported a significant association between occupational use of phenoxy herbicides and chlorophenols and soft-tissue sarcomas and malignant lymphomas. However, persons who spray or apply these substances are concomitantly exposed to other potentially carcinogenic chemicals and oncogenic viruses, which have been found or suspected to play a role in the etiology of these tumors. No study has thoroughly controlled for these other exposures, some of which have been shown to be independently associated with these tumors even after controlling for exposure to phenoxy acids or chlorophenols. On the other hand, it has been found that an observed risk from exposure to phenoxy herbicides disappeared on controlling for some of these concomitant exposures in the rare instance this was attempted. Also, on several occasions, an association has been observed with occupations in which exposure to phenoxys and chlorophenols may occur, but not with the compounds themselves. Accordingly, a detailed review of the evidence from occupational cohort studies was conducted, to see if it corroborates that from case-control studies. It was found that the evidence does not unequivocally incriminate phenoxys and chlorophenols as a cause of these tumors. The results obtained with cohort studies of sprayers and applicators do not corroborate the association reported among this occupational group, in case-control studies. It is possible that the suspected association may well be due, partly or wholly, to one or more of the other concomitant exposures. However, in view of the fact that the majority of the cohorts need further follow-up to be informative, it is concluded that further studies of these cohorts are required before it can be determined whether or not these tumors are caused by exposure to phenoxy acids and chlorophenols. 124 references.

  19. 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

  20. 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

  1. 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

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. [Synthesis of 2-methyl-5-substituted phenoxy-primaquine and antimalarials activity].

    PubMed

    Zhong, B H; Deng, R X; Zhong, J X; Wang, J

    1990-01-01

    In searching for efficient, safe and radically curative agent and causal prophylactics for malaria, seven 2-methyl-5-substituted phenoxy-6-methoxy-8-(1-methyl-4-aminobutylamino)-quinolines (II1-7) were synthesized and their antimalarial activities were compared with the corresponding 4-methyl substituted derivatives of primaquine. The starting material, 2-nitro-4-methoxy-5-bromo-acetanilide (III), was prepared from p-methoxy aniline through acetylation, bromination and nitration. III was then condensed with substituted phenols in the presence of potassium carbonate. The condensed products were subsequently hydrolyzed with dilute alcoholic hydrochloric acid to yield 2-nitro-4-methoxy-5-substituted phenoxy-aniline (V) which underwent Skraup's reaction with 2-butenal to provide the key intermediates 2-methyl-5-substituted phenoxy-6-methoxy-8-nitroquinolines (VI). These 8-nitroquinoline derivatives were reduced to 8-aminoquinoline derivatives (VII). The latter were condensed with 4-bromo-1-phthalimido-pentane and then hydrolyzed with hydrazine hydrate, the final products were obtained as oxalate or succinate. The structure of the target compounds and unknown intermediates were confirmed by elementary and spectral analysis. Primary biological evaluation showed that all compounds II1-7 were much less active than the 4-methyl substituted derivatives and slightly less active than primaquine in both causal prophylactic test against Plasmodium yoelii and suppressive antimalarial test against P. berhei. PMID:2239331

  7. 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.

  8. 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.

  9. 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

  10. 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

  11. 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

  12. Kinetic Study of the Acid Degradation of Lignin Model Compound Intermediates

    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) 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 the proposed mechanisms a kentic study of several possible intermediates was done under similar acidolysis conditions. Epoxystyrene and 1-phenyl-1,2-ethandiol were used as intermediates. 2-phenoxyvinylbenzene was synthesized and subsequently deconstructed in H2SO4. The kinetics and product distribution of these intermediates were then used in confirming our proposed mechanisms.

  13. 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.

  14. 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

  15. Synthesis and Biochemical Evaluation of 3-Phenoxy-1,4-diarylazetidin-2-ones as Tubulin-Targeting Antitumor Agents.

    PubMed

    Greene, Thomas F; Wang, Shu; Greene, Lisa M; Nathwani, Seema M; Pollock, Jade K; Malebari, Azizah M; McCabe, Thomas; Twamley, Brendan; O'Boyle, Niamh M; Zisterer, Daniela M; Meegan, Mary J

    2016-01-14

    Structure-activity relationships for a series of 3-phenoxy-1,4-diarylazetidin-2-ones were investigated, leading to the discovery of a number of potent antiproliferative compounds, including trans-4-(3-hydroxy-4-methoxyphenyl)-3-phenoxy-1-(3,4,5-trimethoxyphenyl)azetidin-2-one (78b) and trans-4-(3-amino-4-methoxyphenyl)-3-phenoxy-1-(3,4,5-trimethoxyphenyl)azetidin-2-one (90b). X-ray crystallography studies indicate the potential importance of the torsional angle between the 1-phenyl "A" ring and 4-phenyl "B" ring for potent antiproliferative activity and that a trans configuration between the 3-phenoxy and 4-phenyl rings is generally optimal. These compounds displayed IC50 values of 38 and 19 nM, respectively, in MCF-7 breast cancer cells, inhibited the polymerization of isolated tubulin in vitro, disrupted the microtubular structure in MCF-7 cells as visualized by confocal microscopy, and caused G2/M arrest and apoptosis. Compound 90b possessed a mean GI50 value of 22 nM in the NCI60 cell line screen, displayed minimal cytotoxicity, and was shown to interact at the colchicine-binding site on β-tubulin. Phosphate and amino acid prodrugs of both 78b and 90b were synthesized, of which the alanine amide 102b retained potency and is a promising candidate for further clinical development. PMID:26680364

  16. 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...

  17. 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...

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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

  3. 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

    The abiotic degradation of soil organic matter to volatile organic compounds was studied intensely over the last years (Keppler et al., 2000; Huber et al., 2009). It was shown that soil organic matter is oxidised due to the presence of iron (III), hydrogen peroxide and chloride and thereby produces diverse alkyl halides, which are emitted into the atmosphere. The formation of polar halogenated compounds like chlorinated acetic acids which are relevant toxic environmental substances was also found in soils and sediments (Kilian et al., 2002). The investigation of the formation of other polar halogenated and non-halogenated compounds like diverse mono- and dicarboxylic acids is going to attain more and more importance. Due to its high acidity oxalic acid might have impacts on the environment e.g., nutrient leaching, plant diseases and negative influence on microbial growth. In this study, the abiotic formation of oxalic acid in soil is examined. For a better understanding of natural degradation processes mechanistic studies were conducted using the model compound catechol as representative for structural elements of the humic substances and its reaction with iron (III) and hydrogen peroxide. Iron is one of the most abundant elements on earth and hydrogen peroxide is produced by bacteria or through incomplete reduction of oxygen. To find suitable parameters for an optimal reaction and a qualitative and quantitative analysis method the following reaction parameters are varied: concentration of iron (III) and hydrogen peroxide, time dependence, pH-value and influence of chloride. Analysis of oxalic acid was performed employing an ion chromatograph equipped with a conductivity detector. The time dependent reaction shows a relatively fast formation of oxalic acid, the optimum yield is achieved after 60 minutes. Compared to the concentration of catechol an excess of hydrogen peroxide as well as a low concentration of iron (III) are required. In absence of chloride the

  4. 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.

  5. 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

  6. 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

  7. 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

  8. 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

  9. 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

  10. Identification of a novel selective peroxisome proliferator-activated receptor alpha agonist, 2-methyl-2-(4-{3-[1-(4-methylbenzyl)-5-oxo-4,5-dihydro-1H-1,2,4-triazol-3-yl]propyl}phenoxy)propanoic acid (LY518674), that produces marked changes in serum lipids and apolipoprotein A-1 expression.

    PubMed

    Singh, Jai Pal; Kauffman, Raymond; Bensch, William; Wang, Guoming; McClelland, Pam; Bean, James; Montrose, Chahrzad; Mantlo, Nathan; Wagle, Asavari

    2005-09-01

    Low high-density lipoprotein-cholesterol (HDL-c) is an important risk factor of coronary artery disease (CAD). Optimum therapy for raising HDL-c is still not available. Identification of novel HDL-raising agents would produce a major impact on CAD. In this study, we have identified a potent (IC50 approximately 24 nM) and selective peroxisome proliferator-activated receptor alpha (PPARalpha) agonist, 2-methyl-2-(4-{3-[1-(4-methylbenzyl)-5-oxo-4,5-dihydro-1H-1,2,4-triazol-3-yl]propyl}phenoxy)propanoic acid (LY518674). In human apolipoprotein A-1 (apoA-1) transgenic mice, LY518674 produced a dose-dependent increase in serum HDL-c, resulting in 208 +/- 15% elevation at optimum dose. A new synthesis of apoA-1 contributed to the increase in HDL-c. LY518674 increased apoA-1 mRNA levels in liver. Moreover, liver slices from animals treated with LY518674 secreted 3- to 6-fold more apoA-1 than control liver slices. In cultured hepatocytes, LY518674 produced 50% higher apoA-1 secretion, which was associated with increase in radiolabeled methionine incorporation in apoA-1. Thus, LY518674 is a potent and selective PPARalpha agonist that produced a much greater increase in serum HDL-c than the known fibrate drugs. The increase in HDL-c was associated with de novo synthesis of apoA-1. PMID:15933217

  11. 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

  12. 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

  13. 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

  14. 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...

  15. 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

  16. 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...

  17. 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

  18. 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

  19. 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

  20. Indanylacetic acid derivatives carrying 4-thiazolyl-phenoxy tail groups, a new class of potent PPAR alpha/gamma/delta pan agonists: synthesis, structure-activity relationship, and in vivo efficacy.

    PubMed

    Rudolph, Joachim; Chen, Libing; Majumdar, Dyuti; Bullock, William H; Burns, Michael; Claus, Thomas; Dela Cruz, Fernando E; Daly, Michelle; Ehrgott, Frederick J; Johnson, Jeffrey S; Livingston, James N; Schoenleber, Robert W; Shapiro, Jeffrey; Yang, Ling; Tsutsumi, Manami; Ma, Xin

    2007-03-01

    Compounds that simultaneously activate the three peroxisome proliferator-activated receptor (PPAR) subtypes alpha, gamma, and delta hold potential to address the adverse metabolic and cardiovascular conditions associated with diabetes and the metabolic syndrome. We recently identified the indanylacetic acid moiety as a well-tunable PPAR agonist head group. Here we report the synthesis and structure-activity relationship (SAR) studies of novel aryl tail group derivatives that led to a new class of potent PPAR pan agonists. While most of the tail group modifications imparted potent PPAR delta agonist activity, improvement of PPAR alpha and gamma activity required the introduction of new heterocyclic substituents that were not known in the PPAR literature. Systematic optimization led to the discovery of 4-thiazolyl-phenyl derivatives with potent PPAR alpha/gamma/delta pan agonistic activity. The lead candidate from this series was found to exhibit excellent ADME properties and superior therapeutic potential compared to known PPAR gamma activating agents by favorably modulating lipid levels in hApoA1 mice and hyperlipidemic hamsters, while normalizing glucose levels in diabetic rodent models. PMID:17274610

  1. 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

  2. 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.

  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. 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.

  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. 2,4-Dinitro-1-phenoxy­benzene

    PubMed Central

    Du, Zhen-Ting; Xu, Yan; Yu, Hong-Rui; Li, Yong

    2010-01-01

    The title compound, C12H8N2O5, was obtained by the reaction of 1-chloro-2,4-dinitro­benzene and phenol in the presence of potassium carbonate. The nitro-substituted benzene ring lies on a mirror plane, with one NO2 group in the same plane and the other disordered across this plane. The phenoxy­benzene unit is placed perpendicular to this mirror, resulting in an exact orthogonal relationship between the phenyl and benzene rings in the mol­ecule. The crystal packing exhibits no significantly short inter­molecular contacts. PMID:21579833

  9. 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

  10. 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

  11. 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

  12. 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

  13. 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

  14. 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.

  15. 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.

  16. 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

  17. 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

  18. 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

  19. 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

  20. Phenoxy resins containing pendent ethynyl groups and cured resins obtained therefrom

    NASA Technical Reports Server (NTRS)

    Hergenrother, P. M. (Inventor)

    1985-01-01

    Phenoxy resins containing pendent ethynyl groups, the process for preparing the same, and the cured resin products obtained therefrom are disclosed. Upon the application of heat, the ethynyl groups react to provide branching and crosslinking with the cure temperature being lowered by using a catalyst if desired but not required. The cured phenoxy resins containing pendent ethynyl groups have improved solvent resistance and higher use temperature than linear uncrosslinked phenoxy resins and are applicable for use as coatings, films, adhesives, composited matrices and molding compounds.

  1. 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

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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

  7. 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.

  8. [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

  9. Process for preparing essentially colorless polyimide film containing phenoxy-linked diamines

    NASA Technical Reports Server (NTRS)

    Stclair, A. K.; Stclair, T. L.

    1986-01-01

    A polyimide film that is approximately 90% transparent at 500 nm, useful for thermal protective coatings and solar cells, and the processes for preparing the same by thermal and chemical conversion are disclosed. An essential feature for achieving maximum optical transparency films requires utilizing recrystallized and/or sublimated specific aromatic diamines and dianhydride monomers and introducing phenoxy or thiophenyl separator groups and isomeric m,m' or o,p'-oriented diamines into the polymer molecular structure. The incorporation of these groups in the polymer structure serves to separate the chromaphoric centers and reduce the formation of inter-chain and intra-chain charge transfer complexes which normally cause absorptions in the UV-visible range. The films may be obtained by hand, brushing, casting, or spraying a layer of polyamic acid solutions onto a surface and thermally converting the applied layer to the polyimide, or the polyamic acid solution can be chemically converted to the polyimide, subsequentially dissolved in an organic solvent, and applied as a polyimide film layer with the solvent therein thermally removed.

  10. 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

  11. 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

  12. 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

  13. 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

  14. 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.

  15. 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...

  16. 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% ...

  17. 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

  18. Characterization of a novel β-cypermethrin-degrading Aspergillus niger YAT strain and the biochemical degradation pathway of β-cypermethrin.

    PubMed

    Deng, Weiqin; Lin, Derong; Yao, Kai; Yuan, Huaiyu; Wang, Zhilong; Li, Jianlong; Zou, Likou; Han, Xinfeng; Zhou, Kang; He, Li; Hu, Xinjie; Liu, Shuliang

    2015-10-01

    Aspergillus niger YAT strain was obtained from Chinese brick tea (Collection number: CGMCC 10,568) and identified on the basis of morphological characteristics and internal transcribed spacer (ITS) sequence. The strain could degrade 54.83 % of β-cypermethrin (β-CY; 50 mg L(-1)) in 7 days and 100 % of 3-phenoxybenzoic acid (3-PBA; 100 mg L(-1)) in 22 h. The half-lives of β-CY and 3-PBA range from 3.573 to 11.748 days and from 5.635 to 12.160 h, respectively. The degradation of β-CY and 3-PBA was further described using first-order kinetic models. The pathway and mechanism of β-CY degraded by YAT were investigated by analyzing the degraded metabolites through high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS). Relevant enzymatic activities and substrate utilization were also investigated. β-CY degradation products were analyzed. Results indicated that YAT strain transformed β-CY into 3-PBA. 3-PBA was then gradually transformed into permethric acid, protocatechuic acid, 3-hydroxy-5-phenoxy benzoic acid, gallic acid, and phenol gradually. The YAT strain can also effectively degrade these metabolites. The results indicated that YAT strain has potential applications in bioremediation of pyrethroid insecticide (PI)-contaminated environments and fermented food. PMID:26022858

  19. 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.

  20. CYP2C8- and CYP3A-mediated C-demethylation of (3-{[(4-tert-butylbenzyl)-(pyridine-3-sulfonyl)-amino]-methyl}-phenoxy)-acetic acid (CP-533,536), an EP2 receptor-selective prostaglandin E2 agonist: characterization of metabolites by high-resolution liquid chromatography-tandem mass spectrometry and liquid chromatography/mass spectrometry-nuclear magnetic resonance.

    PubMed

    Prakash, Chandra; Wang, Weiwei; O'Connell, Thomas; Johnson, Kim A

    2008-10-01

    CP-533,536, (3-{[(4-tert-butyl-benzyl)-(pyridine-3-sulfonyl)-amino]-methyl}-phenoxy)-acetic acid (1), an EP2 receptor-selective prostaglandin E2 agonist, is being developed to aid in the healing of bone fractures. To support the development of this program, in vitro metabolism of 1 was investigated in human liver microsomes and major recombinant human cytochrome P450 (P450) isoforms. 1 was metabolized in vitro by at least three recombinant human P450s: CYP3A4, CYP3A5, and CYP2C8. The turnover of 1 was NADPH-dependent and was completely inhibited by ketoconazole and quercetin in the CYP3A4/5 and CYP2C8 incubations, respectively. The major metabolic pathways were caused by oxidation of the tert-butyl moiety to form the omega-hydroxy metabolite (M4), oxidation of the pyridine moiety, and/or N-dealkylation of the methylphenoxy acetic acid moiety. The alcohol metabolite M4 was further oxidized to the corresponding carboxylic acid M3. In addition to these pathways, three unusual metabolites (M22, M23, and M26) resulting from C-demethylation of the tert-butyl group were identified using high-resolution liquid chromatography/tandem mass spectrometry and liquid chromatography/mass spectrometry/NMR. The C-demethylated metabolites were not detected on incubation of carboxylic acid metabolite M3 with either human liver microsomes or CYP3A/2C8 isoforms, suggesting that these metabolites were not derived from decarboxylation of M3. A possible mechanism for C-demethylation may involve the oxidation of M4 to form an aldehyde metabolite (M24), followed by P450-mediated deformylation, to give an unstable carbon-centered radical and formic acid. The carbon-centered radical intermediate then undergoes either oxygen rebound to form an alcohol metabolite M23 or hydrogen abstraction leading to an olefin metabolite M26. PMID:18653741

  1. [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

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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.

  7. New aspects in the reaction mechanism of phenol with peroxynitrite: the role of phenoxy radicals.

    PubMed

    Daiber, A; Mehl, M; Ullrich, V

    1998-01-01

    The decomposition of peroxynitrite (PON) in aqueous solutions was investigated by monitoring the release of dioxygen as a function of pH together with the various reaction products generated from phenol. This substrate was used as a mechanistic model for tyrosine nitration in prostacyclin synthase for which we have reported a highly efficient nitration and inhibition by PON (Zou, M., Martin, C., and Ullrich, V. (1997) Biol Chem. 378, 707-713). Nitrite as a contaminant and product of PON generated 4-nitrosophenol and some nitrophenols in the acidic pH range. In the alkaline range high amounts of 4-nitrosophenol originated from the disproportionation of PON yielding dioxygen and NOx species. The hydroxylation of phenol occurred between pH 3 and 8 with a maximum at 4.5. The nitration by PON also required a pH between 4 and 8 but had a second maximum between 10 and 12, suggesting that in this pH range phenolate was the reacting species. All isomeric biphenols were found as dimerization products as well as 4-phenoxyphenol (4-hydroxydiphenyl ether), indicating phenoxy radicals as intermediates. Since anisol when incubated under the same conditions yielded only hydroxylation but virtually no nitration products, it was concluded that nitration of phenolic compounds requires a one-electron oxidation as a primary step, followed by addition of the nitrogen dioxide radical. PMID:9851367

  8. 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.

  9. 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

  10. 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

  11. 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

  12. 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.

  13. 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

  14. 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

  15. 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

  16. 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

  17. 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

  18. 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

  19. 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

  20. 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

  1. 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.

  2. 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

  3. INFLUENCE OF ENVIRONMENTAL CHANGES ON DEGRADATION OF CHIRAL POLLUTANTS IN SOILS

    EPA Science Inventory

    Numerous anthropogenic chemicals of environmental concern- including some phenoxy acid herbicides, organophosphorus insecticides, polychlorinated biphenyls, phthalates, freon substi- tutes and some DDT derivatives- are chiral. Their potential biological effects, such as toxicity,...

  4. 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

  5. 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].

  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. 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

  8. 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

  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. 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

  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. 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

  13. 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

  14. 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

  15. 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...

  16. 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...

  17. 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

  18. 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

  19. 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

  20. 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

  1. 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

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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

  7. 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.

  8. 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

  9. 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

  10. 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

  11. 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

  12. 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

  13. 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

  14. 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

  15. 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

  16. 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

  17. 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

  18. Phenoxy herbicides and chlorophenols as risk factors for soft tissue sarcoma and non-Hodgkin's lymphoma

    SciTech Connect

    Woods, J.; Polissar, L.; Severson, R.; Heuser, L.

    1986-09-01

    A population-based case-control study evaluated the relationship between soft tissue sarcoma and non-Hodgkin's lymphoma and past exposure to phenoxy herbicides and chlorophenols in western Washington state. A major purpose of the study was to determine if the risk of cancer was elevated in relation to chemicals potentially contaminated with 2,3,7,8-tetra-chlorodibenzo-p-dioxin (TCDD). A total of 160 men with soft tissue sarcoma and 581 men with non-Hodgkin's lymphoma were group-matched with 694 randomly selected controls and were interviewed in person. Among the general population, no increased risks for either cancer were seen in relation to intensity or duration of past exposure to phenoxy herbicides or chlorophenols. Preliminary risk estimates for specific occupations that involve phenoxy herbicide or chlorophenol exposure included: farmer, herbicide formulator, applicator, forest sprayer, farmland sprayer, work in sprayed area, and work with or manufacture chlorophenyls. In addition, the risks of both soft tissue sarcoma and non-Hodgkin's lymphoma were elevated among men with past exposure to various insecticides, organic solvents and metals, and among those with preexisting compromise of the immune system. Multivariate studies are in progress to ascertain the contribution of diverse factors to the risks of soft tissue sarcoma or non-Hodgkin's lymphoma in association with phenoxy herbicides, chlorophenols, and/or TCDD.

  19. Ideal gas thermodynamic properties for the phenyl, phenoxy, and o-biphenyl radicals

    NASA Technical Reports Server (NTRS)

    Burcat, A.; Zeleznik, F. J.; Mcbride, B. J.

    1985-01-01

    Ideal gas thermodynamic properties of the phenyl and o-biphenyl radicals, their deuterated analogs and the phenoxy radical were calculated to 5000 K using estimated vibrational frequencies and structures. The ideal gas thermodynamic properties of benzene, biphenyl, their deuterated analogs and phenyl were also calculated.

  20. 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

  1. 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

  2. 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

  3. 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)

  4. 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

  5. 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

  6. 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.

  7. 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

  8. 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

  9. 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

  10. 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.

  11. 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).

  12. 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

  13. 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

  14. 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

  15. 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

  16. 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

  17. 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.

  18. 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

  19. 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

  20. 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)

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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

  7. 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

  8. 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

  9. 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

  10. 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.

  11. 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

  12. 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

  13. [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

  14. 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

  15. 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

  16. 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

  17. 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

  18. 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.

  19. Synthesis, characterization and comparative evaluation of phenoxy ring containing long chain gemini imidazolium and pyridinium amphiphiles.

    PubMed

    Bhadani, Avinash; Kataria, Hardeep; Singh, Sukhprit

    2011-09-01

    Two series of phenoxy ring containing long chain imidazolium and pyridinium based gemini amphiphiles have been synthesized from renewable cardanol oil having different spacers (i. e. -S-(CH(2))(n)-S-, where n is 2, 3, 4 & 6). Critical micelle concentration (cmc) of these new gemini amphiphiles has been determined by conductivity method. Further, these new cationic amphiphiles have been evaluated for their DNA binding capability by agarose gel electrophoresis, ethidium bromide exclusion experiments and transmission electron microscopy (TEM). The cytotoxicity of these new amphiphiles have been evaluated by MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Comparative studies of these phenoxy ring containing long chain gemini imidazolium amphiphiles and their pyridinium analogues depicted low cmc values of the later but greater DNA interaction capability and low cytotoxicity of the former series of amphiphiles. PMID:21676409

  20. Ultrafast dynamics of excited state of phenoxy-phthalocyanines in solution

    NASA Astrophysics Data System (ADS)

    Yao, Cheng-Bao; Yan, Xiao-Yan; Sun, Da-Wei; Sui, Yan-Li; Li, Jin; Sun, Wen-Jun; Li, Qiang-Hua; Yang, Shou-Bin

    2016-01-01

    Ultrafast dynamics of the excited state of 2,9,16,23-phenoxy-phthalocyanine (Pc1) and 2,9,16,23-phenoxy-phthalocyanine-zinc (Pc2) has been investigated using femtosecond transient absorption (TA) and time-resolved fluorescence (TRFL) techniques. The observed dynamics of femtosecond TA and TRFL experiments are similar, which demonstrated the intrinsic properties of the excitation and the relaxation processes in both kinds of phthalocyanines with two decay components. A multi level model has been proposed to explain the photophysical processes after Soret-band excitation. The results show that the fast decay component dynamics comes from the intramolecular vibrational relaxation, the slower ones from the internal conversion. The samples are expected to be a potential candidate for optical applications and photodynamic therapy.

  1. 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

  2. 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.

  3. 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

  4. Tris(4-acetamido­phenoxy­methyl)methanol 0.7-hydrate

    PubMed Central

    Parrish, Damon A.; Juromski, Katie; Marteel-Parrish, Anne; Damavarapu, Reddy; Zang, Maoxi; Paritosh, Dave

    2008-01-01

    The asymmetric unit of the title compound, C28H31N3O7·0.7H2O, contains a mol­ecule of tris­(4-acetamido­phenoxy­meth­yl)methanol and 0.7 of a water mol­ecule. An extensive hydrogen-bonding network includes inter­actions between all components of the crystal structure. PMID:21581059

  5. 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

    This study investigated the in vitro degradation of porous poly(DL-lactic-co-glycolic acid) (PLGA) foams during a 20-week period in pH 7.4 phosphate-buffered saline (PBS) at 37 degrees C and their in vivo degradation following implantation in rat mesentery for up to 8 weeks. Three types of PLGA 85 : 15 and three types of 50 : 50 foams were fabricated using a solvent-casting, particulate-leaching technique. The two types had initial salt weight fraction of 80 and 90%, and a salt particle size of 106-150 microm, while the third type had 90% initial weight fraction of salt in the size range 0-53 microm. The porosities of the resulting foams were 0.82, 0.89, and 0.85 for PLGA 85 : 15, and 0.73, 0.87, and 0.84 for PLGA 50 : 50 foams, respectively. The corresponding median pore diameters were 30, 50, and 17 microm for PLGA 85: 15, and 19, 17, and 17 microm for PLGA 50 : 50. The in vitro and in vivo degradation kinetics of PLGA 85: 15 foams were independent of pore morphology with insignificant variation in foam weight, thickness, pore distribution, compressive creep behavior, and morphology during degradation. The in vitro foam half-lives based on the weight average molecular weight were 11.1 +/- 1.8 (80%, 106-150 microm), 12.0 +/- 2.0 (90%, 106-150 microm), and 11.6 +/- 1.3 (90%, 0-53 microm) weeks, similar to the corresponding values of 9.4 +/- 2.2, 14.3 +/- 1.5, and 13.7 +/- 3.3 weeks for in vivo degradation. In contrast, all PLGA 50 : 50 foams exhibited significant change in foam weight, water absorption, and pore distribution after 6-8 weeks of incubation with PBS. The in vitro foam half-lives were 3.3 +/- 0.3 (80%, 106-150 microm), 3.0 +/- 0.3 (90%, 106-150 microm), and 3.2 +/- 0.1 (90%, 0-53 microm) weeks, and the corresponding in vivo half-lives were 1.9 micro 0.1, 2.2 +/- 0.2, and 2.4 +/- 0.2 weeks. The significantly shorter half-lives of PLGA 50: 50 compared to 85: 15 foams indicated their faster degradation both in vitro and in vivo. In addition, PLGA 50: 50

  6. 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

  7. 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

  8. 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

  9. 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

  10. 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

  11. [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

  12. 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

  13. 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

  14. 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.

  15. 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

  16. 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

  17. 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.

  18. 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.

  19. 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

  20. 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

  1. 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

  2. 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

  3. 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

  4. 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

  5. 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.

  6. 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

  7. 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

  8. 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

  9. 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).

  10. 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