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Sample records for resin acid degraders

  1. Oxidative degradation of low and intermediate level Radioactive organic wastes 2. Acid decomposition on spent Ion-Exchange resins

    International Nuclear Information System (INIS)

    Ghattas, N.K.; Eskander, S.B.

    1995-01-01

    The present work provides a simplified, effective and economic method for the chemical decomposition of radioactively contaminated solid organic waste, especially spent ion - exchange resins. The goal is to achieve volume reduction and to avoid technical problems encountered in processes used for similar purposes (incineration, pyrolysis). Factors efficiency and kinetics of the oxidation of the ion exchange resins in acid medium using hydrogen peroxide as oxidant, namely, duration of treatment and the acid to resin ratio were studied systematically on a laboratory scale. Moreover the percent composition of the off-gas evolved during the decomposition process was analysed. 3 figs., 5 tabs

  2. Subsurface degradation of resin-based composites.

    Science.gov (United States)

    Bagheri, Rafat; Tyas, Martin J; Burrow, Michael F

    2007-08-01

    To determine the depth of a degraded subsurface layer produced in dental composites as a result of exposure to lactic acid or NaOH, by observing the penetration of AgNO(3) solution. Specimens were prepared from four resin composites; Point 4 (Kerr), Premise (Kerr), Filtek Supreme (3M/ESPE), Ceram X (Dentsply), and two polyacid-modified resin composites; Dyract (Dentsply) and F2000 (3M/ESPE). The specimens were immersed in distilled water for 1 week, transferred to one of three aqueous media at 60 degrees C for 2 weeks; distilled water, 0.01mol/L lactic acid or 0.1N NaOH, washed and immersed in 50% (w/w) aqueous silver nitrate for 10 days at 60 degrees C and placed in a photodeveloper solution. After reduction of the silver, specimens were embedded in epoxy resin, sectioned and polished, coated with carbon, and examined by backscattered mode scanning electron microscopy. The depth of silver penetration into the degraded area was measured from the SEM micrographs. Energy dispersive analysis X-ray (EDAX) was used to confirm the presence of silver. NaOH produced the greatest depth of degradation and lactic acid the least. Premise showed the greatest depth of silver penetration when subjected to NaOH, and Filtek Supreme the second with peeling of the surface and cracking, whereas F2000 and Point 4 showed the least in NaOH and lactic acid. ANOVA and Tukey's test showed that the depth of silver penetration was material and solution dependent, and the differences were significant for most of the materials (P<0.05).

  3. Determination of degradation conditions of exchange resins containing technetium

    International Nuclear Information System (INIS)

    Rivera S, A.; Monroy G, F.; Quintero P, E.

    2014-10-01

    The quantification of Tc-99 in spent exchange resins, coming from nuclear power plants, is indispensable to define their administration. The Tc-99 is a pure beta emitter of 210000 years of half-life, volatile and of a high mobility in water and soil. For this reason, the objective of this work is to establish a digestion method of ionic exchange resins containing technetium that retains more than 95% of this radioisotope. Mineralization tests were carried out of a resin Amberlite IRN-150 by means of an oxidation heat, in acid medium, varying the resin mass, the medium volume, the media type, the temperature and the digestion time. The digested samples were analyzed by gas chromatography to estimate the grade of their degradation. The 99m Tc was used as tracer to determine the technetium percentage recovered after mineralizing the resin. The digestion process depends on the temperature and the resin mass. At higher temperature better mineralization of samples and to greater resin mass to a constant temperature, less degradation of the resin. The spectra beta of the 99m Tc and 99 Tc are presented. (Author)

  4. Diterpene resin acids in conifers.

    Science.gov (United States)

    Keeling, Christopher I; Bohlmann, Jörg

    2006-11-01

    Diterpene resin acids are a significant component of conifer oleoresin, which is a viscous mixture of terpenoids present constitutively or inducibly upon herbivore or pathogen attack and comprises one form of chemical resistance to such attacks. This review focuses on the recent discoveries in the chemistry, biosynthesis, molecular biology, regulation, and biology of these compounds in conifers.

  5. Thermal degradation kinetics and antimicrobial studies of terpolymer resins

    Directory of Open Access Journals (Sweden)

    Abdul R. Burkanudeen

    2016-09-01

    Full Text Available The terpolymer (ASF was synthesized by condensation of anthranilic acid and salicylic acid with formaldehyde in the presence of glacial acetic acid as a catalyst at 140 ± 2 °C for 6 h with varying proportions of reactants. The terpolymer ASF-I was characterized by elemental analysis, FTIR, 1H NMR and 13C NMR spectroscopy. The thermal decomposition behavior of ASF-I, II and III terpolymers was studied using thermogravimetric analysis (TGA in a static nitrogen atmosphere at a heating rate of 20 °C/min. Freeman–Carroll, Sharp–Wentworth and Phadnis–Deshpande methods were used to calculate the thermal activation energy (Ea the order of reaction (n, entropy change (ΔS, free energy change (ΔF, apparent entropy (S∗ and frequency factor (Z. Phadnis–Deshpande method was used to propose the thermal degradation model for the decomposition pattern of ASF-I terpolymer resin. The order of the decomposition reaction was found to be 0.901. The thermal activation energy determined with the help of these methods was in good agreement with each other. The ASF-I, II and III resins were tested for their inhibitory action against pathogenic bacteria and fungi. The resins show potent inhibitory action against bacteria, such as Escherichia coli, Klebsiella, Staphylococcus aureus and Pseudomonas aeruginosa and fungi viz. Aspergillus flavus, Aspergillus niger, Penicillium sp., Candida albicans, Cryptococcus neoformans and Mucor sp.

  6. Microbial degradation of resins fractionated from Arabian light crude oil

    International Nuclear Information System (INIS)

    Venkateswaran, K.; Hoaki, T.; Kato, M.; Maruyama, T.

    1995-01-01

    Sediment samples from the Japanese coasts were screened for microorganisms able to degrade resin components of crude oil. A mixed population that could degrade 35% of 5000 ppm resin in 15 days was obtained. This population also metabolized 50% of saturates and aromatics present in crude oil (5000 ppm) in 7 days. A Pseudomonas sp., isolated from the mixed population, emulsified and degraded 30% of resins. It also degraded saturates and aromatics (30%) present in crude oil (5000 ppm). These results were obtained from Iatroscan analysis. Degradation of crude oil was also analyzed by gas chromatography (GC). The peaks corresponding to known aliphatic hydrocarbons in crude oil greatly decreased within the first two days of incubation in the cultures of the RY-mixed population and of Pseudomonas strain UN3. Aromatic compounds detected as a broad peak by GC were significantly degraded at day 7 by Pseudomonas strain UN3, and at day 15 by the RY-mixed population. Investigations are ongoing to determine the genetic basis for the ability of these organisms to grow on the resin fractions of crude oil as a sole source of carbon and energy. 28 refs., 4 figs., 1 tab

  7. Degradation, Fatigue, and Failure of Resin Dental Composite Materials

    Energy Technology Data Exchange (ETDEWEB)

    Drummond, J.L. (UIC)

    2008-11-03

    The intent of this article is to review the numerous factors that affect the mechanical properties of particle- or fiber-filler-containing indirect dental resin composite materials. The focus will be on the effects of degradation due to aging in different media, mainly water and water and ethanol, cyclic loading, and mixed-mode loading on flexure strength and fracture toughness. Several selected papers will be examined in detail with respect to mixed and cyclic loading, and 3D tomography with multi-axial compression specimens. The main cause of failure, for most dental resin composites, is the breakdown of the resin matrix and/or the interface between the filler and the resin matrix. In clinical studies, it appears that failure in the first 5 years is a restoration issue (technique or material selection); after that time period, failure most often results from secondary decay.

  8. Benzoxazine resin/carbon nanotube nanostructured composite's degradation kinetic.

    Science.gov (United States)

    Untem, Flávia O; Botelho, Edson C; Rezende, Mirabel C; Costa, Michelle Leali

    2014-07-01

    In the last decades a new class of thermoset phenolic resin is emerging as a substitute of the traditional epoxy and phenolic resins in the aircraft industry. This new class is called polybenzoxazines and its associates the epoxy resin's mechanical properties and phenolic resin's thermal and flame retardant properties, resulting in a resin with superior properties when analyzed with the others singly. The introduction of carbon nanotubes in low concentration into polymeric matrices can produce nanostructured materials with good properties. Thus, in this study, nanostructured composites of benzoxazine resin were processed with different concentration of carbon nanotubes (0.1%, 0.5% and 1.0% w/w). In order to evaluate the thermostability of the benzoxazine resin and its nanostructured composites, it was performed a degradation kinetic study using the thermogravimetric technique. For that, the analysis have been done with the temperature ranging from 25 degrees C to 1000 degrees C at nitrogen atmosphere (100 mL x min(-1)) and in different heating rates (2, 4, 6, 8, 10 and 20 degrees C x min(-1)), in order to obtain the kinetic parameters (activation energy, E(a), and pre-exponential factor, A), based on Ozawa-Wall-Flynn model. The results showed excellent agreement between the thermogravimetric curves obtained and the Ozawa-Wall-Flynn method. The degradation kinetic study showed that the introduction of carbon nanotubes in the benzoxazine matrix does not change the thermostability of the resin, so that it does not have a significant influence in the shelf life of the material.

  9. 21 CFR 573.120 - Acrylamide-acrylic acid resin.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Acrylamide-acrylic acid resin. 573.120 Section 573.120 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Food Additive Listing § 573.120 Acrylamide-acrylic acid resin. Acrylamide-acrylic acid resin...

  10. Degradation of ion spent resin using the Fenton's reagent

    International Nuclear Information System (INIS)

    Araujo, Leandro Goulart de

    2013-01-01

    The most common method for spent radioactive ion exchange resin treatment is its immobilization in cement, which reduces the radionuclides release into the environment. Although this method is efficient, it increases considerably the final volume of the waste due to the low incorporation capacity. The objective of this work was to develop a degradation method of spent resins arising from the nuclear research reactor located at the Nuclear and Energy Research Institute (IPEN-CNEN/SP), using an Advanced Oxidation Process (AOP) with Fenton's reagents. This method would allow a higher incorporation in cement. Three different resins were evaluated: cationic, anionic and a mixture of both resins. The reactions were conducted varying the catalyst concentration (25, 50, 100 and 150 mM), the volume of hydrogen peroxide (320 to 460 mL), and three different temperatures, 50, 60 and 70 deg C. Degradation of about 98% was achieved using a 50 mM catalyst solution and 330 mL of hydrogen peroxide solution. The most efficient temperature was 60 deg C. (author)

  11. Studies of transformation and particle-binding of resin acids during oxidative treatment of effluent from two New Zealand pulp mills.

    Science.gov (United States)

    Kanber, S A; Langdon, A G; Wilkins, A L

    2008-02-01

    Reactor studies of aerobic degradation of effluent from the first and last ponds of the treatment system of two New Zealand pulp and paper mills indicated that filterable BOD(5), resin acids and transformed resin acids, free and bound, degraded at similar rates. During oxidative treatment the resin acids of untreated effluent became increasingly bound to particulate material and a sediment high in abiet-13-enoic acid was formed.

  12. EPICOR-II resin characterization and proposed methods for degradation analysis. Rev. 1

    International Nuclear Information System (INIS)

    Doyle, J.D.; McConnell, J.W. Jr.; Sanders, R.D. Sr.

    1984-06-01

    One goal of the EPICOR-II Research and Disposition Program is the examination of the EPICOR-II organic ion-exchange resins for physical and chemical degradation. This report summarizes preliminary information necessary for the evaluation of the resins for degradation. Degradation of the synthetic organic ion-exchange resins should be efficiently and accurately measurable by using the baseline data provided by the nonirradiated resin characterization. The degradation threshold is about 10 8 rads, approximately the same dose rate the resins will have received by the examination date. If degradation has not occurred at the first examination point, later examinations will detect resin degradation using the same analytical methods. The results from the characterization tests will yield practical and useful data on the actual effects of radiation on commercial synthetic organic ion-exchange resins. 10 references, 12 figures

  13. Determination of degradation conditions of exchange resins containing technetium; Determinacion de condiciones de degradacion de resinas de intercambio conteniendo tecnecio

    Energy Technology Data Exchange (ETDEWEB)

    Rivera S, A.; Monroy G, F.; Quintero P, E., E-mail: aa_1190@hotmail.com [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2014-10-15

    The quantification of Tc-99 in spent exchange resins, coming from nuclear power plants, is indispensable to define their administration. The Tc-99 is a pure beta emitter of 210000 years of half-life, volatile and of a high mobility in water and soil. For this reason, the objective of this work is to establish a digestion method of ionic exchange resins containing technetium that retains more than 95% of this radioisotope. Mineralization tests were carried out of a resin Amberlite IRN-150 by means of an oxidation heat, in acid medium, varying the resin mass, the medium volume, the media type, the temperature and the digestion time. The digested samples were analyzed by gas chromatography to estimate the grade of their degradation. The {sup 99m}Tc was used as tracer to determine the technetium percentage recovered after mineralizing the resin. The digestion process depends on the temperature and the resin mass. At higher temperature better mineralization of samples and to greater resin mass to a constant temperature, less degradation of the resin. The spectra beta of the {sup 99m}Tc and {sup 99}Tc are presented. (Author)

  14. Oxidation of resin acids in colophony (rosin) and its implications for patch testing.

    Science.gov (United States)

    Sadhra, S; Foulds, I S; Gray, C N

    1998-08-01

    Commercial preparations of colophony (rosin) used for patch testing are made from unmodified rosin in pet. and may be stored for some considerable time before being used. This would be satisfactory if the composition and dermatological activity of the preparations were both reproducible and stable, but investigations by the authors have shown that the resin acids undergo progressive and substantial oxidation and that the dermatological activity of the preparations increases significantly with time. This may be a cause of inconsistent patch test results unless the composition can be stabilized. Gas liquid chromatography (GLC) analysis of a raw rosin sample and its commercial patch test preparation has shown that they both contained the same resin acids, but the concentration of the abietic type resin acids was found to be lower in the patch test preparations. The degradation of resin acids is due to their atmospheric oxidation, which may occur during the preparation and storage of the commercial rosin patch test preparation. The susceptibility of individual resin acids to atmospheric oxidation was demonstrated by analysing a sample of raw Portuguese gum rosin, which was then left exposed to air and light. Most of the resin acids were found to undergo oxidation at a rate which gradually diminished. More importantly, it is presumed that the concentration of oxidized resin acids increased correspondingly, and these have been shown to be more dermatologically active than the unoxidised resin acids. The rate of decrease of resin acid concentration was found to be in the following order: neoabietic>levopimaric and palustric>abietic>dehydroabetic acid. The pimaric type resin acids were found to be relatively inert to atmospheric oxidation when compared with the abietic type resin acids. Patch testing with the resulting partly oxidized Portuguese rosin produced positive reactions at a 35% higher frequency than the raw Portuguese rosin. The study demonstrates that the

  15. Antimicrobial activity of resin acid derivatives.

    Science.gov (United States)

    Savluchinske-Feio, Sonia; Curto, Maria João Marcelo; Gigante, Bárbara; Roseiro, J Carlos

    2006-09-01

    The wide potential of resin acids as bioactive agents gave rise to a growing effort in the search for new applications of the natural forms and their derivatives. In some of these compounds, the antimicrobial activity is associated to the presence in the molecules of functional groups such as the hydroxyl, aldehyde, and ketone or to their cis or trans configurations. The resin acid family covers a spectrum of antimicrobial activities against several microorganisms, from bacteria to fungi, in which the mode of action was studied by electron microscopy. The morphological alterations are consistent with an unspecific mode of action causing inhibition of the fungal growth or damaging the fungal cells in parallel with a mechanism of resistance based on the retention of the compound by the lipid accumulation. The sterol composition of phytopathogenic fungi Botrytis cinerea and Lophodermium seditiosum treated with methyl cis-7-oxo-deisopropyldehydroabietate revealed the presence of ergosterol (M+ 396) and dihydroergosterol (M+ 398) in both cultures showing that this compound did not interfere with the ergosterol metabolic pathway of both fungi.

  16. Study of Curing Kinetics and Thermal Degradation of UV Curable Epoxy Acrylate Resin

    Directory of Open Access Journals (Sweden)

    Amrita Sharma

    2008-01-01

    Full Text Available Blends of epoxy acrylate resins (acid values 3, 6.5 & 10 mg KOH/gm Solid with monofunctional monomers (ethoxylated phenol monoacrylate were prepared by physical mixing, having weight ratio 50:50. These blends were cured by using UV radiations in presence of photo initiator (Darocure 1173. The thermal degradation kinetics of these resin blends were studied, using thermo gravimetric analysis in nitrogen atmosphere at a heating rate of 10°C/min. by applying Coats-Red fern equation. According to the analysis, all the coating films degrade in two steps. In the first step of degradation kinetics, R2M follows 1.75 order (n=1.75 and all other coating films follow second order (n=2 kinetics. In second step, R2M & R3M follow half order (n=0.5 kinetics and R1M follow first order (n=1 degradation kinetics. Order of the reaction is obtained on the basis of best fit analysis, and all the parameters were confirmed by regression analysis. From the reaction order, value of activation energy (E and pre exponential factor (Z were calculated by the slop and intercept of the plot between X and Y, respectively.

  17. Kinetic study of ion exchange in phosphoric acid chelating resin

    International Nuclear Information System (INIS)

    Brikci-Nigassa, Mounir; Hamouche, Hafida

    1995-11-01

    Uranium may be recovered as a by product of wet phosphoric acid using a method based on specific ion exchange resins. These resins called chelates contain amino-phosphonic functional groups. The resin studied in this work is a purolite S-940; uranium may be loaded on this resin from 30% P2O5 phosphoric acid in its reduced state. The influence of different parameters on the successive steps of the process have been studied in batch experiments: uranium reduction, loading and oxydation. Uranium may be eluted with ammonium carbonate and the resin regeneration may be done with hydrochloric acid.Ferric ions reduce the effective resin capacity considerably and inert fixation conditions are proposed to enhance uranium loading

  18. Chelating ion exchange with macroreticular hydroxamic acid resins

    International Nuclear Information System (INIS)

    Phillips, R.J.

    1980-01-01

    The synthesis, reactions, and analytical applications of hydroxamic acids, including chelating resins with this functional group, are reviewed. A procedure for attaching N-phenyl hydroxamic acid groups to Amberlite XAD-4 is described. The extraction of 20 metal ions from 2M hydrochloric acid by this resin is discussed. Conditions for the quantitative extraction and back-extraction of 9 ions are reported. The results are compared with work on solvent extraction with N-phenylbenzohydroxamic acid. Procedures for attaching N-methyl and N-substituted hydroxamic acid groups to Amberlite XAD-4 are described. The N-phenyl, N-methyl, and N-unsubstituted hydroxamic acid resins are compared with respect to metal-ion complexation. The scope of applications for hydroxamic acid resins is investigated by studying the extraction of 19 metal ions as a function of pH. The resins are especially suitable for the extraction of zirconium(IV), titanium(IV), and uranium(IV) from strongly acidic solution. Aluminum(III) is separated from calcium and phosphate by extraction at pH 4. The use of the resins for the purification of reagents, concentration of trace constituents, and chromatographic separation is demonstrated

  19. Chelating ion exchange with macroreticular hydroxamic acid resins

    International Nuclear Information System (INIS)

    Phillips, R.J.

    1980-01-01

    The synthesis, reactions, and analytical applications of hydroxamic acids, including chelating resins with this functional group, are reviewed. A procedure for attaching N-phenyl hydroxamic acid groups to Amberlite XAD-4 is described. The extraction of 20 metal ions from 2 M hydrochloric acid by this resin is discussed. Conditions for the quantitative extraction and back-extraction of 9 ions are reported. Results are compared with work on solvent extraction with N-phenylbenzohydroxamic acid. Procedures for attaching N-methyl and N-unsubstituted hydroxamic acid groups to Amberlite XAD-4 are described. The N-phenyl, N-methyl, and N-unsubstituted hydroxamic acid resins are compared with respect to metal-ion complexation. The scope of applications for hydroxamic acid resins is investigated by studying the extraction of 19 metal ions as a function of pH. The resins are especially suitable for the extraction of zirconium(IV), titanium(IV), and uranium(IV) from strongly acidic solution. Aluminum(III) is separated from calcium and phosphate by extraction at pH 4. The use of the resins for the purification of reagents, concentration of trace constituents, and chromatographic separation is demonstrated

  20. Enhanced vanillin production from ferulic acid using adsorbent resin.

    Science.gov (United States)

    Hua, Dongliang; Ma, Cuiqing; Song, Lifu; Lin, Shan; Zhang, Zhaobin; Deng, Zixin; Xu, Ping

    2007-03-01

    High vanillin productivity was achieved in the batch biotransformation of ferulic acid by Streptomyces sp. strain V-1. Due to the toxicity of vanillin and the product inhibition, fed-batch biotransformation with high concentration of ferulic acid was unsuccessful. To solve this problem and improve the vanillin yield, a biotransformation strategy using adsorbent resin was investigated. Several macroporous adsorbent resins were chosen to adsorb vanillin in situ during the bioconversion. Resin DM11 was found to be the best, which adsorbed the most vanillin and the least ferulic acid. When 8% resin DM11 (wet w/v) was added to the biotransformation system, 45 g l(-1) ferulic acid could be added continually and 19.2 g l(-1) vanillin was obtained within 55 h, which was the highest vanillin yield by bioconversion until now. This yield was remarkable for exceeding the crystallization concentration of vanillin and therefore had far-reaching consequence in its downstream processing.

  1. Long-term degradation of resin-based cements in substances present in the oral environment: influence of activation mode

    Directory of Open Access Journals (Sweden)

    Eduardo Moreira da SILVA

    2013-06-01

    Full Text Available Indirect restorations in contact with free gingival margins or principally within the gingival sulcus, where the presence of organic acids produced by oral biofilm is higher, may present faster degradation of the resin-based cement pellicle. Objectives To investigate the degradation of four resin-based cements: Rely X ARC (R, Variolink II (V, Enforce (E and All Cem (A, after immersion in distilled water (DW, lactic acid (LA and artificial saliva (AS and to analyze the influence of the activation mode on this response. Material and Methods Two activation modes were evaluated: chemical (Ch and dual (D. In the dual activation, a two-millimeter thick ceramic disk (IPS Empress System was interposed between the specimen and light-curing unit tip. Specimens were desiccated, immersed in distilled water, artificial saliva and lactic acid 0.1 M at 37°C for 180 days, weighed daily for the first 7 days, and after 14, 21, 28, 90 and 180 days and were desiccated again. Sorption and solubility (µg/mm 3 were calculated based on ISO 4049. The data were submitted to multifactor analysis of variance (MANOVA and Tukey's HSD test for media comparisons (α=0.05. Results Sorption was higher after immersion in LA (pD (p<0.05. The lowest solubility was presented by R (p<0.05. Conclusions Lactic acid increased the degradation of resin-based cements. Moreover, the physical component of activation, i.e., light-activation, contributed to a low degradation of resin-based cements.

  2. Synthesis and thermal degradation studies of melamine formaldehyde resins.

    Science.gov (United States)

    Ullah, Sami; Bustam, M A; Nadeem, M; Naz, M Y; Tan, W L; Shariff, A M

    2014-01-01

    Melamine formaldehyde (MF) resins have been synthesized at different reaction temperature and pH values. Different molar ratios of melamine and formaldehyde were used to synthesize the corresponding resins. The prepared resin samples were characterized by using molecular weight determination viscometry and thermogravimetric analysis (TGA). The maximum percentage of solid content (69.7%) was obtained at pH 8.5 and 75°C temperature. The molecular weight of MF resin was increased with an increase of melamine monomer concentration. The highest residual weight 14.125 wt.% was obtained with sample 10.

  3. Synthesis and Thermal Degradation Studies of Melamine Formaldehyde Resins

    Directory of Open Access Journals (Sweden)

    Sami Ullah

    2014-01-01

    Full Text Available Melamine formaldehyde (MF resins have been synthesized at different reaction temperature and pH values. Different molar ratios of melamine and formaldehyde were used to synthesize the corresponding resins. The prepared resin samples were characterized by using molecular weight determination viscometry and thermogravimetric analysis (TGA. The maximum percentage of solid content (69.7% was obtained at pH 8.5 and 75°C temperature. The molecular weight of MF resin was increased with an increase of melamine monomer concentration. The highest residual weight 14.125 wt.% was obtained with sample 10.

  4. Uranium extraction from sulfuric acid solution using anion exchange resin

    International Nuclear Information System (INIS)

    Sheta, M. E.; Abdel Aal, M. M.; Kandil, A. T.

    2012-12-01

    Uranium is currently recovered from sulfuric acid leach liquor using anion exchange resin as Amberlite IRA 402 (CT). This technology is based on fact that, uranium exists as anionic complexes. This takes place by controlling the pH of the solution, agitation time, temperature and resin to solution ratio (R/S). In this work, batch stirrer tank used for uranium extraction from sulfate medium and after extraction, elution process was done using 1M NaCl solution. After extraction and elution process, the resin was separated from the system and uranium was determined in the solution. (Author)

  5. Experimental investigation of coating degradation during simultaneous acid and erosive particle exposure

    DEFF Research Database (Denmark)

    Møller, Victor Buhl; Dam-Johansen, Kim; Frankær, Sarah Maria

    of a simultaneous exposure. To investigate this, a pilot-scale stirred acid leaching tank, containing erosive particles and acidic solutions, has been designed and constructed. Resin types considered are amine-cured novolac epoxy and vinyl ester. Transient coating degradation is mapped through visual inspection...

  6. Degradation of resins in EPICOR-II prefilters from Three Mile Island

    International Nuclear Information System (INIS)

    McConnell, J.W. Jr.; Sanders, R.D. Sr.

    1986-01-01

    The Low-Level Waste Data Base Development--EPICOR-II Resin/Liner Investigation Program funded by the U.S. Nuclear Regulatory Commission is investigating the chemical and physical conditions of the synthetic ion exchange resins contained in several EPICOR-II prefilters. Those prefilters were used during cleanup of contaminated water from the Three Mile Island Nuclear Power Station after the March 1979 accident. This paper summarizes results and analyses of the second sampling of resins from prefilters PF-8 and -20. Results are compared with baseline data from tests performed on unirradiated resins supplied by Epicor, Inc. to determine if degradation has occurred due to the high internal radiation dose. Results also are compared with results from tests performed on resins obtained from the first sampling of those two prefilters

  7. Selective separation of indium by iminodiacetic acid chelating resin

    Energy Technology Data Exchange (ETDEWEB)

    Fortes, M.C.B.; Benedetto, J.S. [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Martins, A.H. [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Dept. de Engenharia Metalurgica e de Materiais]. E-mail: ahmartin@demet.ufmg.br

    2007-04-15

    - Indium can be recovered by treating residues, flue dusts, slags, and metallic intermediates in zinc smelting. This paper investigates the adsorption characteristics of indium and iron on an iminodiacetic acid chelating resin, Amberlite{sup R} IRC748 (Rohm and Haas Co.-USA). High concentrations of iron are always present in the aqueous feed solution of indium recovery. In addition, the chemical behaviour of iron in adsorptive systems is similar to that of indium. The metal concentrations in the aqueous solution were based on typical indium sulfate leach liquor obtained from zinc hydrometallurgical processing in a Brazilian plant. The ionic adsorption experiments were carried out by the continuous column method. Amberlite{sup R} IRC748 resin had a high affinity for indium under acidic conditions. Indium ions adsorbed onto the polymeric resin were eluted with a 0.5 mol/dm{sup 3} sulphuric acid solution passed through the resin bed in the column. 99.5% pure indium sulfate aqueous solution was obtained using the iminodiacetic acid chelating resin Amberlite{sup R} IRC748. (author)

  8. Raman spectroscopic study of the aging and nitration of actinide processing anion-exchange resins in concentrated nitric acid

    International Nuclear Information System (INIS)

    Buscher, C. T.; Donohoe, R. J.; Mecklenburg, S. L.; Berg, J. M.; Tait, C. D.; Huchton, K. M.; Morris, D. E.

    1999-01-01

    Degradation of two types of anion exchange resins, Dowex 11 and Reillex HPQ, from the action of concentrated nitric acid (4 to 12 M) and radiolysis [from depleted uranium as UO 2 2+ nitrate species and 239 Pu as Pu(IV) nitrate species] was followed as a function of time with Raman vibrational spectroscopy. Elevated temperatures (∼50 degree sign C) were used in the absence of actinide metal loading to simulate longer exposures of the resin to a HNO 3 process stream and waste storage conditions. In the absence of actinide loading, only minor changes in the Dowex resin at acid concentrations ≤10 M were observed, while at 12 M acid concentration, the emergence of a Raman peak at 1345 cm-1 indicates the addition of nitro functional groups to the resin. Similar studies with the Reillex resin show it to be more resistant to nitric acid attack at all acid concentrations. Incorporation of weakly radioactive depleted uranium as the UO 2 2+ nitrate species to the ion-exchange sites of Dowex 11 under differing nitric acid concentrations (6 to 12 M) at room temperature showed no Raman evidence of resin degradation or nitration, even after several hundred days of contact. In contrast, Raman spectra for Dowex 11 in the presence of 239 Pu as Pu(IV) nitrate species reveal numerous changes indicating resin alterations, including a new mode at 1345 cm-1 consistent with a Pu(IV)-nitrate catalyzed addition of nitro groups to the resin backbone. (c) 2000 Society for Applied Spectroscopy

  9. Degradation of dental resin composites during intra-oral wear

    NARCIS (Netherlands)

    Yulianto, Heribertus Dedy Kusuma

    2017-01-01

    Dental resin composites have become an integral part of modern dentistry and used worldwide to restore missing tooth structures, to modify tooth color and anatomical contour, and to enhance aesthetics and function. The dentist should be aware that, the aggressive complexity of the oral environment

  10. [Absorption and isolation of macroporous resin for five salvianolic acids from Salviae mitiorrhizae].

    Science.gov (United States)

    Wang, Yan-Yan; Zhu, Jing-Bo; Li, Lin; Jin, Yue

    2008-05-01

    To study the adsorption of the macroporous resin for the five salvianolic acids (danshen su, rosmarinic acid, protocate chualdehyde, salvianolic acid B, salvianolic acid A, extracted from Salviae mitiorrhizae. The five salvianolic acids were employed as an index, and the change of them in the static and dynamic absorbent was detected by HPLC, respectively. HP20 resin was a suitable marcoporous resin to purify salvianolic acids. The dynamic adsorption capacity of rosmarinic acid, salvianolic acid B and salvianolic acid A was 30.506 mg x g(-1) (dry resin), 36.996 mg x g(-1), (dry resin), 43.85 mg x g(-1) (dry resin) respectively. It is not suitable that danshensu and protocate chualdehyde are the evaluation indexes for using 8 macroporous resins to purify salvianolic acids.

  11. Anaerobic microbial associations degrading aminoaromatic acids

    NARCIS (Netherlands)

    Kotova, I.; Savelieva, O.; Dyakonova, A.T.; Sklyar, V.; Kalyushnyi, S.V.; Stams, A.J.M.; Netrusov, A.

    2005-01-01

    Anaerobic microbial associations have been isolated that degrade aminoaromatic acids to methane and carbon dioxide at high rates. Significant differences between the morphological, cytological, and physiological traits of cultures isolated from samples of adapted and unadapted sludge are shown. The

  12. Degradation of resin-dentin bonds of etch-and-rinse adhesive system to primary and permanent teeth

    Directory of Open Access Journals (Sweden)

    Tathiane Larissa Lenzi

    2012-12-01

    Full Text Available The aim of this in vitro study was to compare the degradation of resin-dentin bonds of an etch-and-rinse adhesive system to primary and permanent teeth. Flat superficial coronal dentin surfaces from 5 primary second molars and 5 permanent third molars were etched with phosphoric acid and bonded with an adhesive system (Adper Single Bond 2, 3M ESPE. Blocks of resin composite (Z250, 3M ESPE were built up and the teeth sectioned to produce bonded sticks with a 0.8 mm² cross-sectional area. The sticks of each tooth were randomly divided and assigned to be subjected to microtensile testing immediately (24 h or after aging by water storage (6 months. Data were analyzed by two-way repeated measures ANOVA and Tukey post hoc test (α = 0.05. Failure mode was evaluated using a stereomicroscope (400×. Microtensile values significantly decreased after the 6 months aging, independent of the dentin substrate. In 24 h, the values obtained to primary dentin were lower compared with permanent dentin. This difference was not maintained after aging. Adhesive/mixed failure was predominant in all experimental groups. In conclusion, degradation of resin-dentin bonds of the etch-and-rinse adhesive system occurred after 6 months of water storage; however, the reduction in bond strength values was higher for permanent teeth.

  13. Evaluation of Degradation in Nanofilled Adhesive Resins Using Quantitative Light-Induced Fluorescence

    Directory of Open Access Journals (Sweden)

    Tae-Young Park

    2014-01-01

    Full Text Available The aim of this study was to evaluate degradation in commercial dental nanofilled adhesive resins using quantitative light-induced fluorescence (QLF. Three adhesives were selected: D/E resin (DR, Single Bond Plus (SB, and G-Bond (GB. The adhesives were mixed with porphyrin for the QLF analysis. Specimens were prepared by dispensing blended adhesives into a flexible mold and polymerizing. Then, the QLF analysis of the specimens was done and the porphyrin values (Simple Plaque Score and ΔR were measured. After thermocycling of the specimens (5000 cycles, 5 to 55°C for the degradation, the specimens were assayed by QLF again. The porphyrin values were analyzed using paired t-test at a 95% confidence level. A significant reduction in SPS was observed in all groups after thermocycling. The ΔR significantly decreased after thermocycling except area ΔR30 of SB group. Overall, porphyrin values decreased after thermocycling which indicates that the degradation of the adhesive resins may be measured by the change of porphyrin value. The QLF method could be used to evaluate the degradation of adhesive resin.

  14. Bile acid sequestrants : more than simple resins

    NARCIS (Netherlands)

    Out, Carolien; Groen, Albert K.; Brufau, Gemma

    Purpose of review Bile acid sequestrants (BAS) have been used for more than 50 years in the treatment of hypercholesterolemia. The last decade, bile acids are emerging as integrated regulators of metabolism via induction of various signal transduction pathways. Consequently, BAS treatment may exert

  15. Surface roughness of composite resins subjected to hydrochloric acid.

    Science.gov (United States)

    Roque, Ana Carolina Cabral; Bohner, Lauren Oliveira Lima; de Godoi, Ana Paula Terossi; Colucci, Vivian; Corona, Silmara Aparecida Milori; Catirse, Alma Blásida Concepción Elizaur Benitez

    2015-01-01

    The purpose of this study was to determine the influence of hydrochloric acid on surface roughness of composite resins subjected to brushing. Sixty samples measuring 2 mm thick x 6 mm diameter were prepared and used as experimental units. The study presented a 3x2 factorial design, in which the factors were composite resin (n=20), at 3 levels: microhybrid composite (Z100), nanofilled composite (FiltekTM Supreme), nanohybrid composite (Ice), and acid challenge (n=10) at 2 levels: absence and presence. Acid challenge was performed by immersion of specimens in hydrochloric acid (pH 1.2) for 1 min, 4 times per day for 7 days. The specimens not subjected to acid challenge were stored in 15 mL of artificial saliva at 37 oC. Afterwards, all specimens were submitted to abrasive challenge by a brushing cycle performed with a 200 g weight at a speed of 356 rpm, totaling 17.8 cycles. Surface roughness measurements (Ra) were performed and analyzed by ANOVA and Tukey test (p≤0.05). Surface roughness values were higher in the presence (1.07±0.24) as compared with the absence of hydrochloric acid (0.72±0.04). Surface roughness values were higher for microhybrid (1.01±0.27) compared with nanofilled (0.68 ±0.09) and nanohybrid (0.48±0.15) composites when the specimens were not subjects to acid challenge. In the presence of hydrochloric acid, microhybrid (1.26±0.28) and nanofilled (1.18±0,30) composites presents higher surface roughness values compared with nanohybrid (0.77±0.15). The hydrochloric acid affected the surface roughness of composite resin subjected to brushing.

  16. The degradation of strong basic anion exchange resins and mixed-bed ion-exchange resins: Effect of degradation products on radionuclide speciation

    International Nuclear Information System (INIS)

    Loon, L.R. van; Hummel, W.

    1999-01-01

    The most important water-soluble products of the radiolytic degradation of anion exchange resins in a cementitious environment are ammonia and methylamines. These ligands do not form complexes with most radionuclides. Exceptions are Ni, Ag, and Pd, which form strong complexes with amines. Other degradation products of anion and mixed-bed ion-exchange resins are of no importance concerning the complexation of trivalent radionuclides. This is shown indirectly by adsorption experiments: The degradation products do not have a significant effect on the adsorption of Eu(III) on calcite. The effect of ammonia and methylamines on the complexation of Ni, Ag, and Pd is investigated by chemical modeling. For Ni and Ag, rather reliable predictions can be made using available thermodynamic data. In the case of Pd, large uncertainties are encountered due to unreliable data and gaps in the set of important species. The system Pd(II)-ammonia-water is explored in detail. Predominant species are inferred by chemical analogy, and their thermodynamic data are estimated. The uncertainty in these estimated and measured but unreliable data is bound by qualitative and quantitative chemical reasoning

  17. Comparison of XAD macroporous resins for the concentration of fulvic acid from aqueous solution

    Science.gov (United States)

    Aiken, G.R.

    1979-01-01

    Five macroreticular, nonlonlc AmberlHe XAD resins were evaluated for concentration and Isolation of fulvlc acid from aqueous solution. The capacity of each resin for fulvlc acid was measured by both batch and column techniques. Elution efficiencies were determined by desorptlon with 0.1 N NaOH. Highest recoveries were obtained with the acrylic ester resins which proved to be most efficient for both adsorption and elution of fulvlc acid. Compared to the acrylic ester resins, usefulness of the styrene dvlnybenzene resins to remove fulvlc acid is limited because of slow diffusion-controlled adsorption and formation of charge-transfer complexes, which hinders elution. ?? 1979 American Chemical Society.

  18. Removal of dyes from water using crosslinked aminomethane sulfonic acid based resin.

    Science.gov (United States)

    Kaner, Damla; Saraç, Ayfer; Senkal, Bahire Filiz

    2010-08-01

    A new polymeric resin with amino sulfonic acid pendant functions has been prepared for the extraction of acidic and basic dyes from water. Beaded polymer supports were prepared by suspension polymerization of vinyl benzyl chloride (0.9 mol) and ethylene glycol dimethacrylate (0.1 mol). The resulting copolymer beads were modified with amino methane sulfonic acid. The dye adsorption capacity of the resin was found as 0.16 g dye/g resin for ramazol black and 0.15 g dye/g resin for crystal violet. The pH depending measurements and dye sorption kinetics of the resin were also investigated.

  19. Oxidation-resistant acidic resins prepared by partial carbonization as cocatalysts in synthesis of adipic acid.

    Science.gov (United States)

    Wei, Huijuan; Li, Hongbian; Liu, Yangqing; Jin, Peng; Wang, Xiangyu; Li, Baojun

    2012-08-01

    The oxidation-resistant acidic resins are of great importance for the catalytic oxidation systems. In this paper, the oxidatively stable acidic resins are obtained from the cation ion exchange resins (CIERs) through the thermal treatment in N(2) atmosphere. The structure and properties of the thermally treated CIERs were characterized by chemical analysis, Fourier transform infrared (FT-IR) spectra, acid capacity measurement and scanning electron microscope (SEM). The thermally treated CIERs possess high acid capacity up to 4.09 mmol g(-1). A partial carbonization is observed in the thermal treatment process of CIERs, but the morphology of resin spheres maintains well. The as-prepared CIERs are used as solid acids to assist the hydrogen peroxide oxidation of cyclohexene to adipic acid (ADA) with tungstic acid as the catalyst precursor. The improved yields of ADA in the recycling reaction are obtained in the presence of acidic CIERs. Meanwhile, the unproductive decomposition of H(2)O(2) is effectively suppressed. The high yields of ADA (about 81%) are kept by the thermally treated CIERs even after the fifth cycle. The thermally treated CIERs exhibit excellent acid-catalytic performance and possess remarkable oxidation-resistant capability.

  20. Separation and recovery of nucleic acids with improved biological activity by acid-degradable polyacrylamide gel electrophoresis.

    Science.gov (United States)

    Kim, Yoon Kyung; Kwon, Young Jik

    2010-05-01

    One of the fundamental challenges in studying biomacromolecules (e.g. nucleic acids and proteins) and their complexes in a biological system is isolating them in their structurally and functionally intact forms. Electrophoresis offers convenient and efficient separation and analysis of biomacromolecules but recovery of separated biomacromolecules is a significant challenge. In this study, DNAs of various sizes were separated by electrophoresis in an acid-degradable polyacrylamide gel. Almost 100% of the nucleic acids were recovered after the identified gel bands were hydrolyzed under a mildly acidic condition and purified using anion exchange resin. Further concentration by centrifugal filtration and a second purification using ion exchange column chromatography yielded 44-84% of DNA. The second conventional (non-degradable) gel electrophoresis confirmed that the nucleic acids recovered from acid-degradable gel bands preserved their electrophoretic properties through acidic gel hydrolysis, purification, and concentration processes. The plasmid DNA recovered from acid-degradable gel transfected cells significantly more efficiently than the starting plasmid DNA (i.e. improved biological activity via acid-degradable PAGE). Separation of other types of nucleic acids such as small interfering RNA using this convenient and efficient technique was also demonstrated.

  1. Water and UV degradable lactic acid polymers

    Science.gov (United States)

    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.

  2. The radiolytic and chemical degradation of organic ion exchange resins under alkaline conditions: effect on radionuclide speciation

    International Nuclear Information System (INIS)

    Loon, L. van; Hummel, W.

    1995-10-01

    The formation of water soluble organic ligands by the radiolytic and chemical degradation of several ion exchange resins was investigated under conditions close to those of the near field of a cementitious repository. The most important degradation products were characterised and their role on radionuclide speciation evaluated thoroughly. Irradiation of strong acidic cation exchange resins (Powdex PCH and Lewatite S-100) resulted in the formation of mainly sulphate and dissolved organic carbon. A small part of the carbon (10-20%) could be identified as oxalate. The identity of the remainder is unknown. Complexation studies with Cu 2+ and Ni 2+ showed the presence of two ligands: oxalate and ligand X. Although ligand X could not be identified, it could be characterised by its concentration, a deprotonation constant and a complexation constant for the NiX complex. The influence of oxalate and ligand X on the speciation of radionuclides is examined in detail. For oxalate no significant influence on the speciation of radionuclides is expected. The stronger complexing ligand X may exert some influence depending on its concentration and the values of other parameters. These critical parameters are discussed and limiting values are evaluated. In absence of irradiation, no evidence for the formation of ligands was found. Irradiation of strong basic anion exchange resins (Powdex PAO and Lewatite M-500) resulted in the formation of mainly ammonia, amines and dissolved organic carbon. Up to 50% of the carbon could be identified as methyl-, dimethyl- and trimethylamine. Complexation studies with Eu 3+ showed that the complexing capacity under near field conditions was negligible. The speciation of cations such as Ag, Ni, Cu and Pd can be influenced by the presence of amins. The strongest amine-complexes are formed with Pd and therefore, as an example, the aqueous Pd-ammonia system is examined in great detail. (author) 30 figs., 10 tabs., refs

  3. The radiolytic and chemical degradation of organic ion exchange resins under alkaline conditions: effect on radionuclide speciation

    Energy Technology Data Exchange (ETDEWEB)

    Loon, L. van; Hummel, W. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1995-10-01

    The formation of water soluble organic ligands by the radiolytic and chemical degradation of several ion exchange resins was investigated under conditions close to those of the near field of a cementitious repository. The most important degradation products were characterised and their role on radionuclide speciation evaluated thoroughly. Irradiation of strong acidic cation exchange resins (Powdex PCH and Lewatite S-100) resulted in the formation of mainly sulphate and dissolved organic carbon. A small part of the carbon (10-20%) could be identified as oxalate. The identity of the remainder is unknown. Complexation studies with Cu{sup 2+} and Ni{sup 2+} showed the presence of two ligands: oxalate and ligand X. Although ligand X could not be identified, it could be characterised by its concentration, a deprotonation constant and a complexation constant for the NiX complex. The influence of oxalate and ligand X on the speciation of radionuclides is examined in detail. For oxalate no significant influence on the speciation of radionuclides is expected. The stronger complexing ligand X may exert some influence depending on its concentration and the values of other parameters. These critical parameters are discussed and limiting values are evaluated. In absence of irradiation, no evidence for the formation of ligands was found. Irradiation of strong basic anion exchange resins (Powdex PAO and Lewatite M-500) resulted in the formation of mainly ammonia, amines and dissolved organic carbon. Up to 50% of the carbon could be identified as methyl-, dimethyl- and trimethylamine. Complexation studies with Eu{sup 3+} showed that the complexing capacity under near field conditions was negligible. The speciation of cations such as Ag, Ni, Cu and Pd can be influenced by the presence of amins. The strongest amine-complexes are formed with Pd and therefore, as an example, the aqueous Pd-ammonia system is examined in great detail. (author) 30 figs., 10 tabs., refs.

  4. Non-destructive evaluation by terahertz spectroscopy for penetration of acid solutions into epoxy resin

    Directory of Open Access Journals (Sweden)

    M. Kusano

    2016-11-01

    Full Text Available Epoxy resins are used as high-performance thermosetting linings to protect substrates under corrosive environments. However, in a severe corrosive chemical solution, such protective layers may degrade with long time due to penetrations of solvent and solute molecules into resin network. In this regard, the terahertz time-domain spectroscopy (THz-TDS is a promising tool for non-destructive evaluation of the penetrant amounts due to high transparency of such plastic materials and high sensitivity to the molecular vibrations in terahertz spectral range. In this work, the complex refractive indexes n and κ of epoxy specimens were measured after immersion into sulfuric acid solutions and compared with penetrated mass fractions of water and acid ions. It was found that n and κ depended linearly with water and sulfuric acid mass fraction in specimens, and κ of sulfuric acid immersed specimens was lager at higher frequency. While the calculated Δκ agreed well with THz-TDS measurement by THz-TDS, the calculated Δn was higher than the measurement. The difference may be attributed to the water and sulfuric states in the specimen.

  5. Anaerobic degradation of linoleic oleic acids

    Energy Technology Data Exchange (ETDEWEB)

    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.

  6. Nanobiocatalytic Degradation of Acid Orange 7

    Science.gov (United States)

    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.

  7. Aerobic microbial degradation of glucoisosaccharinic Acid.

    Science.gov (United States)

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

    1984-02-01

    alpha-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.

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

    International Nuclear Information System (INIS)

    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 (paper)

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

    Science.gov (United States)

    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

  10. Aerobic Microbial Degradation of Glucoisosaccharinic Acid

    OpenAIRE

    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 r...

  11. Usage of methyl ester of tall oil fatty acids and resinic acids as alternative diesel fuel

    International Nuclear Information System (INIS)

    Keskin, Ali; Yasar, Abdulkadir; Guerue, Metin; Altiparmak, Duran

    2010-01-01

    In the experimental study, tall oil fatty and resinic acids were investigated as alternative diesel fuels. The fatty acids, obtained by distilling the crude tall oil, were esterified with methanol in order to obtain tall oil methyl ester (biodiesel). Blends of the methyl ester, resinic acids and diesel fuel were prepared for test fuels. Performance and emission tests of the test fuels were carried out in an unmodified direct injection diesel engine on full load conditions. The results showed that the specific fuel consumption (SFC) with the blend fuels did not show a significant change. CO emission and smoke level decreased up to 23.91% and 19.40%, respectively. In general, NO x emissions showed on trend of increasing with the blend fuels (up to 25.42%). CO 2 emissions did not vary with the blend fuels significantly.

  12. Usage of methyl ester of tall oil fatty acids and resinic acids as alternative diesel fuel

    Energy Technology Data Exchange (ETDEWEB)

    Keskin, Ali; Yasar, Abdulkadir [Tarsus Technical Education Faculty, Mersin University, 33500 Mersin (Turkey); Guerue, Metin [Engineering and Architectural Faculty, Gazi University, 06570 Maltepe, Ankara (Turkey); Altiparmak, Duran [Technical Education Faculty, Gazi University, 06500 Ankara (Turkey)

    2010-12-15

    In the experimental study, tall oil fatty and resinic acids were investigated as alternative diesel fuels. The fatty acids, obtained by distilling the crude tall oil, were esterified with methanol in order to obtain tall oil methyl ester (biodiesel). Blends of the methyl ester, resinic acids and diesel fuel were prepared for test fuels. Performance and emission tests of the test fuels were carried out in an unmodified direct injection diesel engine on full load conditions. The results showed that the specific fuel consumption (SFC) with the blend fuels did not show a significant change. CO emission and smoke level decreased up to 23.91% and 19.40%, respectively. In general, NO{sub x} emissions showed on trend of increasing with the blend fuels (up to 25.42%). CO{sub 2} emissions did not vary with the blend fuels significantly. (author)

  13. Experimental studies on long-term thermal degradation of enclosed neutron shielding resin

    International Nuclear Information System (INIS)

    Asano, Ryoji; Niomura, Nagao.

    1993-01-01

    The present works are concerned with the thermal degradation or loss of weight of the mixtures contained in vessels. The resins used is an epoxis, 'NS-4-FR' and the fire resisting material mixed is aluminum hydroxide. Firstly, the effect of temperature on degradation was surveyed on the NS-4-FR by continuous heating tests at different temperatures under unenclosed, or open conditions; 125degC, 150degC, 175degC and 200degC. Then, the effect of difference and shape of materials was surveyed at 150degC. Secondly, continuous heating tests were conducted under open and enclosed conditions at 125degC, 150degC and 175degC and the effect of enclosing the mixtures was obtained. Finally, continuous and cyclic heating tests were conducted under enclosed conditions at 125degC, 150degC and 175degC, which was followed by long-term cyclic heating tests at 150degC for more than one year. As the results, following emperical equation was obtained for the thermal degradation at 150degC of the NS-4-FR: W = 0.55 logD - 0.41 where, W: thermal degradation (weight loss), %, D: heating period, day. From this equation, weight loss in 20 years is obtained as less than 2% which is insignificantly small for shielding effect. (J.P.N.)

  14. Hydroxyl radical mediated degradation of phenylarsonic acid.

    Science.gov (United States)

    Xu, Tielian; Kamat, Prashant V; Joshi, Sachin; Mebel, Alexander M; Cai, Yong; O'Shea, Kevin E

    2007-08-16

    Phenyl-substituted arsonic acids have been widely used as feed additives in the poultry industry. While very few studies have been reported on the environmental impact of these compounds, they have been introduced into the environment through land application of poultry litter in large quantities (about 10(6) kg/year). Phenylarsonic acid (PA) was used as a model for problematic arsonic acids. Dilute aqueous solutions of PA were subjected to gamma radiolysis under hydroxyl radical generating conditions, which showed rapid degradation of PA. Product studies indicate addition of (.)OH to the phenyl ring forms the corresponding phenols as the primary products. Arsenite, H3As(III)O3, and arsenate, H3As(V)O4, were also identified as products. The optimized structures and relative calculated energies (using GAUSSIAN 98, the B3LYP/6-31G(d) method) of the various transient intermediates are consistent with the product studies. Pulse radiolysis was used to determine the rate constants of PA with (.)OH (k = 3.2 x 10(9) M(-1) s(-1)) and SO4(.-) (k = 1.0 x 10(9) M(-1) s(-1)). PA reacts slower toward O(.-) (k = 1.9 x 10(7) M(-1) s(-1)) and N3(.) (no detectable transient), due to the lower oxidation potential of these two radicals. Our results indicate advanced oxidative processes employing (.)OH and SO4(.-) can be effective for the remediation of phenyl-substituted arsonic acids.

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

    Science.gov (United States)

    Deng, Weiqin; Liu, Shuliang; Yao, Kai

    2015-09-04

    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.

  16. Studies concerning the anion ex-change resins catalyzed esterification of epichlorohydrin with organic acids

    Directory of Open Access Journals (Sweden)

    E.I. Muresan

    2009-09-01

    Full Text Available The paper studies the esterification of carboxylic acids with epichlorohydrin over two macroporous strong base anion exchange resins with different polymer matrix. For both resins, the influence of reaction parameters (temperature, catalyst loading, molar ratio on the reaction rate and the yields of the two isomeric esters were investigated.

  17. Effect of phytic acid etchant on resin-dentin bonding: Monomer penetration and stability of dentin collagen.

    Science.gov (United States)

    Kong, Kalyan; Hiraishi, Noriko; Nassar, Mohannad; Otsuki, Masayuki; Yiu, Cynthia K Y; Tagami, Junji

    2017-07-01

    Phytic acid (IP6) works well as an etchant in dentin bonding to remove the smear layer due to its acidity and chelating effect. This study compared the etching effect of IP6 with phosphoric acid (PA) and ethylenediaminetetraacetic acid (EDTA) on resin-dentin bond strength, micromorphology of the etched dentin surface and nanoleakage formation along resin-dentin interfaces and compared the protecting effect against collagen degradation. Dentin disks and flat dentin surfaces were obtained from extracted human teeth. Specimens were etched with 35% PA (15s), 0.5M EDTA (30s) or 1% IP6 (30s). The surfaces and longitudinal sections of the etched dentin disks were observed using field emission scanning electron microscope (FE-SEM). An etch-and-rinse adhesive was used to create composite build up-specimens for microtensile bond strength (μTBS) testing and nanoleakage observation. To evaluate the effect on collagen degradation, demineralized bovine root dentin blocks were challenged with bacterial collagenase and then observed under light microscope. PA- and EDTA- treated groups showed significantly lower μTBS when compared to IP6-treated group. PA showed distinct nanoleakage and severe collagen degradation. Only slight nanoleakage was detected in IP6 group. IP6 showed better effect than EDTA in preventing collagen degradation induced by bacterial collagenase. IP6 effectively removed the smear layer and etched dentin, providing high bond strength values and causing minimal nanoleakage and slight collagen degradation. Copyright © 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  18. Development of melamine modified urea formaldehyde resins based o nstrong acidic pH catalyzed urea formaldehyde polymer

    Science.gov (United States)

    Chung-Yun Hse

    2009-01-01

    To upgrade the performance of urea-formaldehyde (UF) resin bonded particleboards, melamine modified urea-formaldehyde (MUF) resins based on strong acidic pH catalyzed UF polymers were investigated. The study was conducted in a series of two experiments: 1) formulation of MUF resins based on a UF polymer catalyzed with strong acidic pH and 2) determination of the...

  19. Novel bioactive polyester scaffolds prepared from unsaturated resins based on isosorbide and succinic acid

    Energy Technology Data Exchange (ETDEWEB)

    Śmiga-Matuszowicz, Monika, E-mail: monika.smiga-matuszowicz@polsl.pl [Silesian University of Technology, Department of Physical Chemistry and Technology of Polymers, M. Strzody Street 9, 44-100 Gliwice (Poland); Janicki, Bartosz; Jaszcz, Katarzyna; Łukaszczyk, Jan [Silesian University of Technology, Department of Physical Chemistry and Technology of Polymers, M. Strzody Street 9, 44-100 Gliwice (Poland); Kaczmarek, Marcin [Silesian University of Technology, Department of Biomaterials and Medical Devices Engineering, de Gaulle' a Street 66, 41-800 Zabrze (Poland); Lesiak, Marta; Sieroń, Aleksander L. [Medical University of Silesia, Department of General and Molecular Biology and Genetics, Medyków Street 18, 40-752 Katowice (Poland); Simka, Wojciech [Silesian University of Technology, Department of Chemistry, Inorganic Technology and Fuels, B. Krzywoustego Street 6, 44-100 Gliwice (Poland); Mierzwiński, Maciej; Kusz, Damian [Medical University of Silesia, Department of Orthopedics and Traumatology, Ziołowa Street 45, 40-635 Katowice (Poland)

    2014-12-01

    In this study new biodegradable materials obtained by crosslinking poly(3-allyloxy-1,2-propylene succinate) (PSAGE) with oligo(isosorbide maleate) (OMIS) and small amount of methyl methacrylate were investigated. The porous scaffolds were obtained in the presence of a foaming system consisted of calcium carbonate/carboxylic acid mixture, creating in situ porous structure during crosslinking of liquid formulations. The maximum crosslinking temperature and setting time, the cured porous materials morphology as well as the effect of their porosity on mechanical properties and hydrolytic degradation process were evaluated. It was found that the kind of carboxylic acid used in the foaming system influenced compressive strength and compressive modulus of porous scaffolds. The MTS cytotoxicity assay was carried out for OMIS using hFOB1.19 cell line. OMIS resin was found to be non-toxic in wide range of concentrations. On the ground of scanning electron microscopy (SEM) observations and energy X-ray dispersive analysis (EDX) it was found that hydroxyapatite (HA) formation at the scaffolds surfaces within short period of soaking in phosphate buffer solution occurs. After 3 h immersion a compact layer of HA was observed at the surface of the samples. The obtained results suggest potential applicability of resulted new porous crosslinked polymeric materials as temporary bone void fillers. - Highlights: • Isosorbide-based resin was used as a component of biodegradable scaffolds. • CAC/carboxylic acid system was proven as facile method to obtain porous scaffolds. • Porous scaffolds displayed the formation of hydroxyapatite at their surfaces.

  20. Separation of chlorogenic acid from honeysuckle crude extracts by macroporous resins.

    Science.gov (United States)

    Zhang, Bin; Yang, Ruiyuan; Zhao, Yan; Liu, Chun-Zhao

    2008-05-15

    Chlorogenic acid, one of the most bioactive compounds rich in the Chinese medicinal herb honeysuckle, is a natural antioxidant and serves as anti-inflammatory, anti-tumor, anti-mutagenic and anti-carcinogenic agent. An efficient preparative separation process of chlorogenic acid from honeysuckle crude extracts has been developed in the present study. HPD-850 resin offers the best adsorption capacity, and adsorption and desorption ratios for chlorogenic acid among the nine macroporous resins tested, and its adsorption rate at 25 degrees C fit best to the Langmuir isotherm. The adsorption capacity of HPD-850 resin was found to depend strongly on the pH value of the initial adsorption solution. The dynamic adsorption and desorption experiments have been carried out on a HPD-850 resin packed column to optimize the separation process of chlorogenic acid from honeysuckle crude extracts. After one run treatment with HPD-850 resin, the chlorogenic acid content in the final product was increased 4.46-fold from 11.2% to 50.0%, with a recovery yield of 87.9%. The preparative separation of chlorogenic acid can be easily and efficiently achieved via adsorption and desorption on HPD-850 resin, and the method developed will provide a potential approach for large-scale separation and purification of chlorogenic acid for its wide pharmaceutical use.

  1. Mechanical fatigue degradation of ceramics versus resin composites for dental restorations.

    Science.gov (United States)

    Belli, Renan; Geinzer, Eva; Muschweck, Anna; Petschelt, Anselm; Lohbauer, Ulrich

    2014-04-01

    . From all materials, e.max Press and Clearfil Majesty Posterior showed the lowest strength loss (29.6% and 32%, respectively), whereas the other materials lost between 41% and 62% of their flexural strength after cyclic loading. Dental ceramics and resin composite materials show equivalent fatigue strength degradation at loads around 0.5σin values. Apart from the zirconium oxide and the lithium disilicate ceramics, resin composites generally showed better σff after 10,000 cycles than the fluorapatite glass-ceramic and the feldspathic porcelain. Resin composite restorations may be used as an equivalent alternative to glass-rich-ceramic inlays regarding mechanical performance. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  2. Industrial alkyd resins: characterization of pentaerythritol and phthalic acid esters using integrated mass spectrometry.

    Science.gov (United States)

    La Nasa, Jacopo; Degano, Ilaria; Modugno, Francesca; Colombini, Maria Perla

    2015-02-15

    Alkyd resins are synthetic polyesters used as paints and coatings. Current approaches for their analysis do not allow the characterization of pentaerythritol and phthalic acid esters, whose detection is interesting to fully characterize the materials, e.g. for forensic or cultural heritage applications. A combined analytical approach based on Gas Chromatography/Mass Spectrometry (GC/MS), High-Performance Liquid Chromatography (HPLC)/MS and flow injection analysis (FIA)/MS was adopted. GC/MS was used to characterize the fatty acid profile and the polybasic acids in extracts from industrial alkyd resins. HPLC/MS and FIA/MS were used for the characterization of the triglyceride profile of the oil used to manufacture the resin and for the identification of reaction products deriving from the synthesis process. The multi-analytical approach was applied on two different industrial alkyd resins produced from two different oils. The GC/MS analysis was successful in characterizing the fatty acid profile and the aromatic fraction of the resin. The HPLC/MS analysis allowed us to characterize the pentaerythritol and phthalic acid ester and the triglycerides residues from the synthesis process, by studying their high-resolution tandem mass spectra. The application of liquid chromatography coupled with high-resolution tandem mass spectrometry to the study of industrial alkyd resins allowed us to characterize for the first time the esters formed by the transesterification reactions involving pentaerythritol, phthalic acid and triglycerides. Copyright © 2014 John Wiley & Sons, Ltd.

  3. Radiolytic degradation of sorbic acid in isolated systems

    International Nuclear Information System (INIS)

    Thakur, B.R.; Trehan, I.R.; Arya, S.S.

    1990-01-01

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

  4. Interaction between staining and degradation of a composite resin in contact with colored foods

    Directory of Open Access Journals (Sweden)

    Debora Soares-Geraldo

    2011-08-01

    Full Text Available Composite resins might be susceptible to degradation and staining when in contact with some foods and drinks. This study evaluated color alteration and changes in microhardness of a microhybrid composite after immersion in different colored foods and determined whether there was a correlation between these two variables. Eighty composite disks were randomly divided into 8 experimental groups (n = 10: kept dry; deionized water; orange juice; passion fruit juice; grape juice; ketchup; mustard and soy sauce. The disks were individually immersed in their respective test substance at 37 ºC, for a period of 28 days. Superficial analysis of the disk specimens was performed by taking microhardness measurements (Vickers, 50 g load for 45 seconds and color alterations were determined with a spectrophotometer (CINTRA 10- using a CIEL*a*b* system, 400-700 nm wavelength, illuminant d65 and standard observer of 2º at the following times: baseline (before immersion, 1, 7, 14, 21 and 28 days. Results were analyzed by ANOVA and Tukey's test (p < 0.05. Both variables were also submitted to Pearson's correlation test (p < 0.05. The passion fruit group underwent the greatest microhardness change, while the mustard group suffered the greatest color alteration. Significant positive correlation was found between the two variables for the groups deionized water, grape juice, soy sauce and ketchup. Not all color alteration could be associated with surface degradation.

  5. Resin Systems and Chemistry-Degradation Mechanisms and Durability in Long-Term Durability of Polymeric Matrix Composites. Chapter 1

    Science.gov (United States)

    Hinkley, Jeffrey A.; Connell, John W.

    2012-01-01

    In choosing a polymer-matrix composite material for a particular application, a number of factors need to be weighed. Among these are mechanical requirements, fabrication method (e.g. press-molding, resin infusion, filament winding, tape layup), and use conditions. Primary among the environmental exposures encountered in aerospace structures are moisture and elevated temperatures, but certain applications may require resistance to other fluids and solvents, alkaline agents, thermal cycling, radiation, or rapid, localized heating (for example, lightning strike). In this chapter, the main classes of polymer resin systems found in aerospace composites will be discussed. Within each class, their responses to environmental factors and the associated degradation mechanisms will be reviewed.

  6. (Methacrylic Acid-Co-Divinylbenzene) Resin as Filler

    African Journals Online (AJOL)

    divinylbenzene) resin (PMD) as a new filler-binder for direct compression tablets. Methods: Powder properties of PMD and MCC were characterized. Tablets made from PMD and MCC with and without propranolol hydrochloride were evaluated for ...

  7. Permanganate Degradation of Reillex HPQ Ion Exchange Resin for Use in HB-Line

    International Nuclear Information System (INIS)

    Walker, B.W.

    1999-01-01

    This study evaluated the use of Reillex TM HPQ resin as a replacement for the Ionac A-641 resin currently authorized for use in H B-Line. The study concentrated on the ability of the existing alkaline permanganate digestion process to convert spent resin for disposal

  8. Synthesis and characterization of an N-(2-hydroxyethyl)-ethylenediaminetriacetic acid resin

    International Nuclear Information System (INIS)

    Lai, Y.F.

    1977-10-01

    A chelating ion-exchange resin with N-(2-hydroxyethyl)ethylene-diaminetriacetic acid (HEDTA) used as the ligand chemically bonded to XAD-4 by an ester linkage, HEDTA-4, was synthesized. It is stable under normal experimental conditions with the liquid chromatograph. The structure of the resin was confirmed by an infrared spectrum, and by potentiometric titrations. The capacity of the resin was also obtained by potentiometric titration and by a nitrogen analysis. The resin was used to pack a column of 5 mm internal diameter and 5 cm long. The effect of pH on the retention of different metal ions on the resin was studied. It was found that the resin was most selective for chromium(III), copper(II), lead(II), mercury(II), uranium(VI), zirconium(IV) and zinc(II) at a pH of less than 3. Furthermore, the resin proves to be functioning with a chelating mechanism rather than ion-exchange, and it can concentrate trace metal ions in the presence of a large excess of calcium and magnesium. This makes the resin potentially useful for purifying and analyzing drinking water

  9. Resin replica in enamel deproteinization and its effect on acid etching.

    Science.gov (United States)

    Espinosa, Roberto; Valencia, Roberto; Uribe, Mario; Ceja, Israel; Cruz, J; Saadia, Marc

    2010-01-01

    The goal of this in vitro study was to identify the topographical features of deproteinized (NaOCl) and etched with phosphoric acid (H3PO4) enamel surface, compared to phosphoric acid surface alone with a Resin Replica model. Ten extracted lower first and second permanent molars were polished with pumice and water, and then divided into 3 equal buccal sections having similar physical and chemical properties. The enamel surfaces of each group were subjected to the following treatments: Group A: Acid Etching with H3PO4 37% for 15 seconds. Group B: Sodium Hypochlorite (NaOCl) 5.25% for 60 seconds followed by Acid Etching with H3PO4 37% for 15 seconds. Group C; No treatment (control). All the samples were treated as follow: Adhesive and resin were applied to all groups after A, B and C treatment were performed; Then enamel/dentin decalcification and deproteinization and topographic SEM Resin Replica assessment were used to identify resin tags enamel surface quality penetration. Showed that group B reached an area of 7.52 mm of the total surface, with a 5.68 mm2 (73%) resin tag penetration equivalent type I and II etching pattern, 1.71 mm2 (26%) equivalent to type III etching pattern and 0.07 mm2 (1%) unaffected surface. Followed by group A with 7.48 mm2 of the total surface, with a 3.47 mm2 (46 %)resin tag penetration equivalent to type I and II etching pattern, 3.30 mm2 (45%)equivalent to type III etching pattern and 0.71 mm2, and (9%) unaffected surface. Group C did not show any resin tag penetration. A significant statistical diference (P enamel is deproteinizated with 5.25% NaOCl for 1 minute prior H3PO4, the surface and topographical features of the replica resin penetration surface increases significantly with type I-II etching pattern.

  10. Concentration and separation of trace metals with an arsonic acid resin.

    Science.gov (United States)

    Fritz, J S; Moyers, E M

    1976-08-01

    Macroporeus arsonic acid resins with different pore sizes and surface areas were prepared and the properties compared. One of the resins was used for concentration of trace metal ions from dimineralized water, tap-water, and sea-water. The effect of pH and complexing agents on the recovery of metal ions was studied. A method for separation of uranium(VI) and thorium(IV) from each other and from other metal ions was developed.

  11. Selected resin acids in effluent and receiving waters derived from a bleached and unbleached kraft pulp and paper mill

    Science.gov (United States)

    Quinn, B.P.; Booth, M.M.; Delfino, J.J.; Holm, S.E.; Gross, T.S.

    2003-01-01

    Water samples were collected on three dates at 24 sites influenced by effluent from Georgia-Pacific's Palatka Pulp and Paper Mill Operation, a bleached and unbleached kraft mill near Palatka, Florida, USA. The sampling sites were located within the mill retention ponds, Rice Creek, and the St. John's River. Samples were analyzed by gas chromatography-mass spectrometry for abietic, dehydroabietic, and isopimaric acids, all of which are potentially toxic by-products of pulp production. Isopimaric acid concentrations greater than 12 mg/L were measured at the mill's effluent outfall but were less than 20 ??g/L at the end of Rice Creek. This result indicates that the waters of Rice Creek provide dilution or conditions conducive for degradation or sorption of these compounds. Large differences in resin acid concentrations were observed between sampling events. In two sampling events, the maximum observed concentrations were less than 2 mg/L for each analyte. In a third sampling event, all of the compounds were detected at concentrations greater than 10 mg/L. Data from the three sample dates showed that resin acid concentrations were below 20 ??g/L before the confluence of Rice Creek and the St. John's River in all cases.

  12. Effect of the chemical structure of anion exchange resin on the adsorption of humic acid: behavior and mechanism.

    Science.gov (United States)

    Shuang, Chendong; Wang, Jun; Li, Haibo; Li, Aimin; Zhou, Qing

    2015-01-01

    Polystyrenic (PS) anion-exchange resin and polyacrylic (PA) anion-exchange resin were used to investigate the effect of resin chemical structure on the adsorption of humic acid (HA). Due to the rearrangement of HA to form layers that function as barricades to further HA diffusion, PS resin exhibited 12.4 times slower kinetics for the initial adsorption rate and 8.4 times for the diffusion constant in comparison to that of the PA resin. An HA layer and a spherical cluster of HA can be observed on the surface of the PS and PA resins after adsorption, respectively. The considerable difference in HA adsorption between the PS and PA resins was due to the difference in molecule shape for interaction with different resin structures, which can essentially be explained by the hydrophobicity and various interactions of the PS resin. A given amount of HA occupies more positively charged sites and hydrophobic sites on the PS resin than were occupied by the same amount of HA on the PA resin. Increased pH resulted in an increase of HA adsorption onto the PA resin but a decrease in adsorption onto PS resin, as the non-electrostatic adsorption led to electrostatic repulsion between the HA attached to the resin and the HA dissolved in solution. These results suggest higher rates of adsorption and higher regeneration efficiency for interaction of HA with more hydrophilic anion exchange materials. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. In vitro adsorption of oxalic acid and glyoxylic acid onto activated charcoal, resins and hydrous zirconium oxide

    NARCIS (Netherlands)

    Scholtens, R.; Scholten, J.; de Koning, H. W.; Tijssen, J.; ten Hoopen, H. W.; Olthuis, F. M.; Feijen, J.

    1982-01-01

    Patients suffering from primary hyperoxaluria show elevated plasma concentrations of oxalic acid and glyoxylic acid. The in vitro adsorption of these compounds into activated charcoal, a series of neutral and ion exchange resins and onto hydrous zirconium oxide has been investigated. Hydrous

  14. Degradation of hop bitter acids by fungi

    International Nuclear Information System (INIS)

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

    2008-01-01

    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

  15. Large scale purification of puerarin from Puerariae Lobatae Radix through resins adsorption and acid hydrolysis.

    Science.gov (United States)

    Guo, Hai-Dong; Zhang, Qing-Feng; Chen, Ji-Guang; Shangguang, Xin-Cheng; Guo, Yu-Xian

    2015-02-01

    Puerarin is the major isoflavone of Puerariae Lobatae Radix. A method for large scale purification of puerarin was developed through resins adsorption and acid hydrolysis. The adsorption properties of six macroporous resins (D101, S-8, H103, X-5, HPD600, AB-8) were compared through the adsorption kinetics and equilibrium adsorption isotherms. Results showed that H103 resin had the best adsorption rate and capacity. The mass transfer zone motion model was further used for analyzing the fixed bed adsorption of H103 resin. Its length of mass transfer zone with 2mg/ml of puerarin in water and 10% ethanol at flow rate of 10ml/min were 41.6 and 47.5cm, while the equilibrium adsorption capacity was 165.03 and 102.88mg/g, respectively. By using 75% ethanol, puerarin could be well desorbed from the resin with recovery of 97.4%. Subsequently, H103 resin was successfully used for puerarin purification from Puerariae Lobatae Radix. The content of total isoflavones and puerarin in the resin adsorption product were 69.25% and 41.78%, respectively, which were about three times increased compared to the crude extract. Then, the product was hydrolyzed by 2.5M HCl at 90°C for 1h. Puerarin with purity of 90% and a byproduct daidzein with purity of 78% were obtained. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Synthesis of hemicellulose-acrylic acid graft copolymer super water absorbent resin by ultrasonic irradiation technology

    Directory of Open Access Journals (Sweden)

    Fangfang LIU

    2015-12-01

    Full Text Available The hemicellulose super water absorbent resin is prepared by using ultrasonic irradiation technology, with the waste liquid produced during the preparation of viscose fiber which contains a large amount of hemicellulose as raw material, acrylic acid as graft monomer, N,N’-methylene bis acrylamide (NMBA as cross linking agent, and (NH42S2O8-NaHSO3 as the redox initiation system. The synthesis conditions, structure and water absorption ability of resin are discussed. The results indicate that water absorbency of the resin is 311 g/g, the tap water absorbency is 102 g/g, the normal saline absorbency is 55 g/g, and the artificial urine absorbency is 31 g/g under the optimal synthesis conditions, so the resin has great water absorption rate and water retaining capacity. The FT-IR and SEM analysis shows that the resin with honeycomb network structure is prepared. The successfully synthesized of the resin means that the hemicellulose waste liquid can be highly effectively recycled, and it provides a kind of new raw material for the synthesis of super water absorbent resin.

  17. Adsorption performance of salicylic acid on a novel resin with distinctive double pore structure.

    Science.gov (United States)

    Xiao, Guqing; Wen, Ruiming; Liu, Aijiao; He, Guowen; Wu, Dan

    2017-05-05

    Two approaches were used to synthesize two resins with different pore structures. In one way, the CH 2 Cl groups in macroporous chloromethylated polystyrene resin were transformed to methylene bridges, and achieved a hypercrosslinked resin with plentiful micropores (denoted GQ-06). In the other way, 50% of the CH 2 Cl groups in chloromethylated polystyrene resin was used to produce micropores, while the residual 50% of the CH 2 Cl groups was reacted with 2-aminopyridine, and prepared another resin with double pore structure of hypercrosslinked resin and macroporous resin (denoted GQ-11). The adsorption of salicylic acid (SA) on GQ-11 was investigated using GQ-06 as the reference adsorbent. The effect of pH on the adsorption of SA on GQ-06 was consistent with the dissociation curve of SA. The maximum adsorption capacity of SA on GQ-11 was observed at the solution pH of 2.64. The greater adsorption rate of SA on GQ-11 than that of GQ-06 was attributed to its double pore structure. The multifunctional adsorption mechanism of anion exchange and hydrophobic interaction resulted in the larger equilibrium capacity of SA on GQ-11 than that of GQ-06. GQ-06 and GQ-11 could be regenerated by absolute alcohol and 80% of alcohol -0.5mol/L of sodium hydroxide aqueous solution, respectively. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Exposure to acid anhydrides in three resin and one cushioned flooring manufacturing plants.

    Science.gov (United States)

    van Tongeren, M J; Barker, R D; Gardiner, K; Harris, J M; Venables, K M; Taylor, A J; Harrington, J M

    1995-10-01

    Acid anhydrides are reactive organic chemicals of low molecular weight which cause occupational asthma. No previous research on the relationship between exposure to these chemicals and respiratory sensitization and development of occupational asthma has been reported. A retrospective cohort study was carried out in four factories (three alkyd resin factories and one cushioned flooring factory) to investigate the nature of exposure-response relationships for sensitization to phthalic anhydride (PA), trimellitic anhydride (TMA) and maleic anhydride (MA). This paper describes the results of full-shift and task-specific exposure measurements. Exposure to PA was low in relation to the Occupational Exposure Standard (OES). The highest full-shift PA exposures occurred among resin operators in the resin factory that used solid PA as compared to other resin factories where liquid PA was used. Arithmetic mean exposure levels to TMA and MA in the resin factories were well below their respective OESs. Short-term high exposures occurred during loading of acid anhydrides into the reactors and sampling and testing of the resin. Relatively high full-shift exposure to TMA occurred in the cushioned flooring factory, although no high peak exposures were detected.

  19. Sorption of Pu(IV) from nitric acid by bifunctional anion-exchange resins

    International Nuclear Information System (INIS)

    Bartsch, R.A.; Zhang, Z.Y.; Elshani, S.; Zhao, W.; Jarvinen, G.D.; Barr, M.E.; Marsh, S.F.; Chamberlin, R.M.

    1999-01-01

    Anion exchange is attractive for separating plutonium because the Pu(IV) nitrate complex is very strongly sorbed and few other metal ions form competing anionic nitrate complexes. The major disadvantage of this process has been the unusually slow rate at which the Pu(IV) nitrate complex is sorbed by the resin. The paper summarizes the concept of bifunctional anion-exchange resins, proposed mechanism for Pu(IV) sorption, synthesis of the alkylating agent, calculation of K d values from Pu(IV) sorption results, and conclusions from the study of Pu(IV) sorption from 7M nitric acid by macroporous anion-exchange resins including level of crosslinking, level of alkylation, length of spacer, and bifunctional vs. monofunctional anion-exchange resins

  20. Radiation induced degradation of some crystalline amino acids

    International Nuclear Information System (INIS)

    Gejvall, T.; Loefroth, G.

    1975-01-01

    The gamma-radiation induced degradation of five crystalline DL-amino acids, leucine, isoleucine, norleucine, valine, and norvaline, has been quantitatively studied. The major products are carboxylic acids formed by deamination of the amino acids, ammonia, amines formed by decarboxylation of the amino acids, and carbon dioxide. In addition, carbonyl compounds and amides, plus small amounts of hydrogen gas and various hydrocarbons have been detected. The total degradation, (-M), has been determined (by isotope dilution) to be 8 for valine and 14 for leucine. (author)

  1. Green biorefinery: separation of lactic acid from grass silage juice by chromatography using neutral polymeric resin.

    Science.gov (United States)

    Thang, Vu Hong; Novalin, Senad

    2008-07-01

    The aim of this work was to recover lactic acid in undissociated form from grass silage juice. For this aim, chromatographic separation using neutral polymeric resin Amberlite XAD1600 was investigated. Up to now, there is no hint in the literatures about using neutral polymeric resin for lactic acid separation from a mixture. Important factors (flow-rate, concentration of feed and loaded volume) that affect separation performance were firstly investigated with model solutions. The obtained results showed that lactic acid solutions with the purity varying from 93.2% to 99.9% could be obtained at the recovery yields over 99.4%. After that, trials with silage juice were carried out. Due to the complex composition of the feed, the purity of products decreased to 94% at a recovery yield of 97%. Although 99% of inorganic salts and sugars were separated from lactic acid organic acids in general and acetic acid in particular caused a purity problem. It seems that organic acids could not be separated from lactic acid by neutral resin Amberlite XAD1600. Besides the organic acid problem, some amino acids were remained in the products as impurities.

  2. Crypthophilic acids A, B, and C: resin glycosides from aerial parts of Scrophularia crypthophila.

    Science.gov (United States)

    Caliş, Ihsan; Sezgin, Yükselen; Dönmez, Ali A; Rüedi, Peter; Tasdemir, Deniz

    2007-01-01

    The water-soluble part of the methanolic extract from the aerial parts of Scrophularia crypthophila, through chromatographic methods, yielded three new resin glycosides, crypthophilic acids A - C (1-3). Compounds 1-3 are tetraglycosides of (+)-3S,12S-dihydroxypalmitic acid. The structures of these and 10 known compounds were elucidated by spectroscopic and chemical means. All natural resin glycosides known so far have been obtained from Convolvulaceae plants; this is the first report of such glycosides from another, taxonomically unrelated family (Scrophulariaceae).

  3. Dimerisation of isobutene on acidic ion-exchange resins

    OpenAIRE

    Honkela, Maija

    2005-01-01

    Dimerisation of isobutene produces diisobutenes that can be hydrogenated to isooctane (2,2,4-trimethyl pentane). Isooctane can be used as a high octane gasoline component. The aim of this work was to study the selective production of diisobutenes through the dimerisation of isobutene on ion-exchange resin catalysts and to construct kinetic models for the reactions in the system for reactor design purposes. High selectivities for diisobutenes were obtained in the presence of polar componen...

  4. Sequential Isolation of Saturated, Aromatic, Resinic and Asphaltic Fractions Degrading Bacteria from Oil Contaminated Soil in South Sumatera

    Directory of Open Access Journals (Sweden)

    Pingkan Aditiawati

    2012-04-01

    Full Text Available Sequential isolation has been conducted to obtain isolates of saturated, aromatic, resin, and asphaltene fractions degrading bacteria from oil contaminated sites. Five soil samples were collected from South Sumatera. These were analyzed using soil extract medium enriched with oil recovery or Remaining-Oil recovery Degradated (ROD as sole carbon and energy sources according to the isolation stage. ROD at the end of every isolation stage analyzed oil fractions by use of the SARA analysis method. Six isolates of bacteria have been selected, one isolate was fraction saturates degrading bacteria that are Mycobacterium sp. T1H2D4-7 at degradation rate 0.0199 mgs/h with density 8.4x106 cfu/g from stage I. The isolate T2H1D2-4, identified as Pseudomonas sp. was fraction aromatics degrading bacteria at accelerate 0.0141 mgs/h with density 5.1x106 cfu/g are obtained at stage II. Two isolates namely Micrococcus sp. T3H2D4-2 and Pseudomonas sp. T1H1D5-5 were fraction resins degrading bacteria by accelerate 0.0088 mgs/h at density 5.6x106 cfu/g and 0.0089 mgs/h at density 5.7x106 cfu/g are obtained at stage III. Isolation of stage IV has been obtained two isolates Pseudomonas sp. T4H1D3-1and Pseudomonas sp. T4H3D5-4 were fraction asphaltenes degrading bacteria by accelerate 0.0057 mgs/h at density 5.6x106 cfu/g and accelerate 0.0058 mgs/h at density 5.7x106 cfu/g.

  5. New Carbon Source From Microbial Degradation of Pre-Production Resin Pellets from the North Pacific Gyre

    Science.gov (United States)

    Neal, A.; Mielke, R.; Stam, C. N.; Gonsior, M.; Tsapin, A. I.; Lee, G.; Leftwich, B.; Narayan, R.; Coleman, H.; Argyropoulos, N.; Sheavly, S. B.; Gorby, Y. A.

    2011-12-01

    Numerous pollutants are transported through the world's oceans that impact oceanic health. Diffuse sources include land-based runoff, atmospheric depositions, shipping industry wastes, and others. Synthetic polymer marine debris is a multi-faceted problem that includes interactions with environmental toxins, carbon cycling systems, ocean surface chemistry, fine minerals deposition, and nano-particles. The impact that synthetic polymer-microbe interactions have on carbon input into the open ocean is poorly understood. Here we demonstrate that both biotic and abiotic processes contribute to degradation of pre-production resin pellets (PRPs), in open ocean environments and new methodologies to determine carbon loss from this synthetic polymer debris. Our data shows that material degradation of environmental polyethylene PRPs can potentially deposit 13 mg/g to 65 mg/g of carbon per PRP into our marine environments. Environmental pre-production resin pellets were collected on the S/V Kaisei cruise in 2009 which covered over 3,000 nautical miles and sampled over 102,000 m3 of the first 15cm of the water column in the Subtropical Convergence Zone of the North Pacific Gyre. Environmental PRP degradation and the role microbial communities play in this was evaluated using a combination of Fourier transform infrared spectroscopy, environmental scanning electron microscopy, scanning transmission electron microscopy, X-ray microtomography, and ArcGIS mapping. More research is needed to understand the environmental impact of this new carbon source arising from synthetic polymers as they degrade in oceanic environments.

  6. Lactic acid polymers: strong, degradable thermoplastics

    Energy Technology Data Exchange (ETDEWEB)

    Wehrenberg, R.H.

    1981-01-01

    Copolymers of lactic and glycolic acids are being developed by researchers at Battelle and elsewhere as renewable-resource plastics. Other uses include matrices for controlled release of drugs and pesticides as well as in prosthetic devices. In contrast to conventional plastics, lactic acid polymers are biodegradable, and after several months exposure to moisture, these materials convert back to natural harmless products. The properties of lactic acid polymers are examined.

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

    Science.gov (United States)

    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.

  8. Chemically modified polymeric resins for separation of cations, organic acids, and small polar moleculea by high performance liquid chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Morris, John B. [Iowa State Univ., Ames, IA (United States)

    1993-07-01

    This thesis is divided into 4 parts: a review, ion chromatography of metal cations on carboxylic resins, separation of hydrophilic organic acids and small polar compounds on macroporous resin columns, and use of eluent modifiers for liquid chromatographic separation of carboxylic acids using conductivity detection.

  9. Exposure to wood dust, resin acids, and volatile organic compounds during production of wood pellets.

    Science.gov (United States)

    Hagström, Katja; Axelsson, Sara; Arvidsson, Helena; Bryngelsson, Ing-Liss; Lundholm, Cecilia; Eriksson, Kåre

    2008-05-01

    The main aim of this study was to investigate exposure to airborne substances that are potentially harmful to health during the production of wood pellets, including wood dust, monoterpenes, and resin acids, and as an indicator of diesel exhaust nitrogen dioxide. In addition, area measurements were taken to assess background exposure levels of these substances, volatile organic compounds (VOCs), and carbon monoxide. Measurements were taken at four wood pellet production plants from May 2004 to April 2005. Forty-four workers participated in the study, and a total of 68 personal measurements were taken to determine personal exposure to wood dust (inhalable and total dust), resin acids, monoterpenes, and nitrogen dioxide. In addition, 42 measurements of nitrogen dioxide and 71 measurements of total dust, resin acids, monoterpenes, VOCs, and carbon monoxide were taken to quantify their indoor area concentrations. Personal exposure levels to wood dust were high, and a third of the measured levels of inhalable dust exceeded the Swedish occupational exposure limit (OEL) of 2 mg/m3. Parallel measurements of inhalable and total dust indicated that the former were, on average, 3.2 times higher than the latter. The data indicate that workers at the plants are exposed to significant amounts of the resin acid 7-oxodehydroabietic acid in the air, an observation that has not been recorded previously at wood processing and handling plants. The study also found evidence of exposure to dehydroabietic acid, and exposure levels for resin acids approached 74% of the British OEL for colophony, set at 50 microg/m3. Personal exposure levels to monoterpenes and nitrogen dioxide were low. Area sampling measurements indicated that aldehydes and terpenes were the most abundant VOCs, suggesting that measuring personal exposure to aldehydes might be of interest. Carbon monoxide levels were under the detection limit in all area measurements. High wood dust exposure levels are likely to have

  10. Effect of sulfuric acid etching of polyetheretherketone on the shear bond strength to resin cements.

    Science.gov (United States)

    Sproesser, Oliver; Schmidlin, Patrick R; Uhrenbacher, Julia; Roos, Malgorzata; Gernet, Wolfgang; Stawarczyk, Bogna

    2014-10-01

    To examine the influence of etching duration on the bond strength of PEEK substrate in combination with different resin composite cements. In total, 448 PEEK specimens were fabricated, etched with sulfuric acid for 5, 15, 30, 60, 90, 120, and 300 s and then luted with two conventional resin cements (RelyX ARC and Variolink II) and one self-adhesive resin cement (Clearfil SA Cement) (n = 18/subgroup). Non-etched specimens served as the control group. Specimens were stored in distilled water for 28 days at 37°C and shear bond strengths were measured. Data were analyzed nonparametrically using Kruskal-Wallis-H (p sulfuric acid seems to be suitable and effective for PEEK surface pre-treatment, further investigations are required to examine the effect of other adhesive systems and cements.

  11. Esterification of oleic acid with ethanol catalyzed by sulfonated cation exchange resin: Experimental and kinetic studies

    International Nuclear Information System (INIS)

    Jiang, Yuwang; Lu, Jie; Sun, Kaian; Ma, Lingling; Ding, Jincheng

    2013-01-01

    Graphical abstract: - Highlights: • Esterification of oleic acid with ethanol was investigated in the presence of sulfonated cation exchange resin. • We studied kinetic model of the esterification of oleic acid with ethanol according to experimental data. • The proposed kinetic model can well predict oleic acid conversion. - Abstract: This paper investigated the effects of ethanol to oleic acid molar ratio, reaction temperature, catalyst loading, water content and catalyst recycling on sulfonated cation exchange resin in a stirred batch reactor under atmospheric pressure. When the esterification was carried out with an ethanol to oleic acid (42.4 g) molar ratio of 9:1, reflux of ethanol at 82 °C, 20 g of catalyst and 8 h of reaction time, the oleic acid conversion rate reached approximately 93%. A pseudo-homogeneous kinetic model for describing the esterification of oleic acid with ethanol by the sulfonated cation exchange resin was developed on the basis of laboratorial results. The kinetic model can well predict the oleic acid conversion

  12. Tape-stripping as a method for measuring dermal exposure to resin acids during wood pellet production.

    Science.gov (United States)

    Eriksson, Kåre; Hagström, Katja; Axelsson, Sara; Nylander-French, Leena

    2008-03-01

    The purpose of this study was to develop a sensitive and specific method for quantifying dermal exposure to the resin acids 7-oxodehydroabietic acid (7-OXO), dehydroabietic acid (DHAA), abietic acid (AA), and pimaric acid (PA). In addition the method was evaluated in occupational settings during production of wood pellets. Tape-strips were spiked with the substances to evaluate the recovery of the acids from the tape. The removal efficiency of the tape was assessed by tape-stripping a specified area on a glass plate spiked with resin acids. The recovery of the acids from human skin in vivo was evaluated by applying acids in methanol onto the skin of volunteers. Occupational dermal exposure to the resin acids was assessed by tape-stripping the skin of workers involved in the production of wood pellets. The resin acids were analyzed by liquid chromatography mass spectrometry (LC-MS). The limit of detection was 15 pg (7-OXO), 150 pg (DHAA), 285 pg (AA) and 471 pg (PA) per injection. The recovery from spiked tapes was in general 100%. The removal efficiency of the tape was 48-101%. Recovery tests from human skin in vivo showed a mean recovery of 27%. Quantifiable amounts of resin acids were observed on four different skin areas with an increase in exposure during a work shift. This study shows that occupational dermal exposure to resin acids can be assessed by tape-stripping and quantified by LC-MS.

  13. Resistance to bond degradation between dual-cure resin cements and pre-treated sintered CAD-CAM dental ceramics.

    Science.gov (United States)

    Osorio, Raquel; Castillo-de Oyagüe, Raquel; Monticelli, Francesca; Osorio, Estrella; Toledano, Manuel

    2012-07-01

    To evaluate the bond stability of resin cements when luted to glass-reinforced alumina and zirconia CAD/CAM dental ceramics. Eighteen glass-infiltrated alumina and eighteen densely sintered zirconia blocks were randomly conditioned as follows: Group 1: No treatment; Group 2: Sandblasting (125 µm Al₂O₃-particles); and Group 3: Silica-coating (50 µm silica-modified Al₂O₃-particles). Composite samples were randomly bonded to the pretreated ceramic surfaces using different resin cements: Subgroup 1: Clearfil Esthetic Cement (CEC); Subgroup 2: RelyX Unicem (RXU); and Subgroup 3: Calibra (CAL). After 24 h, bonded specimens were cut into 1 ± 0.1 mm² sticks. One-half of the beams were tested for microtensile bond strength (MTBS). The remaining one-half was immersed in 10 % NaOCl aqueous solution (NaOClaq) for 5 h before testing. The fracture pattern and morphology of the debonded surfaces were assessed with a field emission gun scanning electron microscope (FEG-SEM). A multiple ANOVA was conducted to analyze the contributions of ceramic composition, surface treatment, resin cement type, and chemical challenging to MTBS. The Tukey test was run for multiple comparisons (p Resin-ceramic interfacial longevity depended on cement selection rather than on surface pre-treatments. The MDP-containing and the self-adhesive resin cements were both suitable for luting CAD/CAM ceramics. Despite both cements being prone to degradation, RXU luted to zirconia or untreated or sandblasted alumina showed the most stable interfaces. CAL experimented spontaneous debonding in all tested groups.

  14. A convenient procedure for the solid-phase synthesis of hydroxamic acids on PEGA resins

    DEFF Research Database (Denmark)

    Nandurkar, Nitin Subhash; Petersen, Rico; Qvortrup, Katrine

    2011-01-01

    An efficient method for the solid-phase synthesis of hydroxamic acids is described. The method comprises the nucleophilic displacement of esters immobilized on PEGA resins with hydroxylamine/sodium hydroxide in isopropanol. The hydroxyaminolysis protocol is compatible with a broad range of PEGA...

  15. Influence of the Functionalization Degree of Acidic Ion-Exchange Resins on Ethyl Octyl Ether Formation

    Czech Academy of Sciences Publication Activity Database

    Guilera, J.; Hanková, Libuše; Jeřábek, Karel; Ramírez, E.; Tejero, J.

    2014-01-01

    Roč. 78, MAY (2014), s. 14-22 ISSN 1381-5148 Grant - others:SEURDO(ES) CTQ2010-16047 Institutional support: RVO:67985858 Keywords : acidic ion-exchange resin * sulfonation degree * ISEC Subject RIV: CC - Organic Chemistry Impact factor: 2.515, year: 2014

  16. Thermal degradation and evolved gas analysis: A polymeric blend of urea formaldehyde (UF and epoxy (DGEBA resin

    Directory of Open Access Journals (Sweden)

    Tansir Ahamad

    2014-12-01

    Full Text Available A polymeric blend has been prepared using urea formaldehyde (UF and epoxy (DGEBA resin in 1:1 mass ratio. The thermal degradation of UF/epoxy resin blend (UFE was investigated by using thermogravimetric analyses (TGA, coupled with FTIR and MS. The results of TGA revealed that the pyrolysis process can be divided into three stages: drying process, fast thermal decomposition and cracking of the sample. There were no solid products except ash content for UFE during combustion at high temperature. The total mass loss during pyrolysis at 775 °C is found to be 97.32%, while 54.14% of the original mass was lost in the second stage between 225 °C and 400 °C. It is observed that the activation energy of the second stage degradation during combustion (6.23 × 10−4 J mol−1 is more than that of pyrolysis (5.89 × 10−4 J mol−1. The emissions of CO2, CO, H2O, HCN, HNCO, and NH3 are identified during thermal degradation of UFE.

  17. Benzoic acid degradation of polyacrylonitrile fibers

    Science.gov (United States)

    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.

  18. Effects of different sulfuric acid etching concentrations on PEEK surface bonding to resin composite.

    Science.gov (United States)

    Chaijareenont, Pisaisit; Prakhamsai, Sasiprapha; Silthampitag, Patcharawan; Takahashi, Hidekazu; Arksornnukit, Mansuang

    2018-01-26

    This study evaluated the effects of surface pretreatment with different concentrations of sulfuric acid etching on surface properties and bonding between Polyetheretherketone (PEEK) and a resin composite. Six groups of surface pretreatment (no pretreatment, etched with 70, 80, 85, 90, and 98% sulfuric acid for 60 s) were treated on PEEK. Surface roughness, scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses were examined. Shear bond strength (SBS) and cross-sectional observations of the interfaces were performed. One-way ANOVA analysis revealed differences in surface roughness and SBS between groups. The 90 and 98% sulfuric acid etching significantly achieved the highest SBS (psulfuric acid etching were suggested to be the optimal concentration to improve adhesion between PEEK and the resin composite.

  19. Kinetics of Ethyl Acetate Synthesis Catalyzed by Acidic Resins

    Science.gov (United States)

    Antunes, Bruno M.; Cardoso, Simao P.; Silva, Carlos M.; Portugal, Ines

    2011-01-01

    A low-cost experiment to carry out the second-order reversible reaction of acetic acid esterification with ethanol to produce ethyl acetate is presented to illustrate concepts of kinetics and reactor modeling. The reaction is performed in a batch reactor, and the acetic acid concentration is measured by acid-base titration versus time. The…

  20. Metabolic engineering of Escherichia coli for producing adipic acid through the reverse adipate-degradation pathway.

    Science.gov (United States)

    Zhao, Mei; Huang, Dixuan; Zhang, Xiaojuan; Koffas, Mattheos A G; Zhou, Jingwen; Deng, Yu

    2018-04-03

    Adipic acid is an important dicarboxylic acid mainly used for the production of nylon 6-6 fibers and resins. Previous studies focused on the biological production of adipic acid directly from different substrates, resulting in low yields and titers. In this study, a five-step reverse adipate-degradation pathway (RADP) identified in Thermobifida fusca has been reconstructed in Escherichia coli BL21 (DE3). The resulting strain (Mad136) produced 0.3gL -1 adipic acid with a 11.1% theoretical yield in shaken flasks, and we confirmed that the step catalyzed by 5-carboxy-2-pentenoyl-CoA reductase (Tfu_1647) as the rate-limiting step of the RADP. Overexpression of Tfu_1647 by pTrc99A carried by strain Mad146 produced with a 49.5% theoretical yield in shaken flasks. We further eliminated pathways for major metabolites competing for carbon flux by CRISPR/Cas9 and deleted the succinate-CoA ligase gene to promote accumulation of succinyl-CoA, which is the precursor for adipic acid synthesis. The final engineered strain Mad123146, which could achieve 93.1% of the theoretical yield in the shaken flask, was able to produce 68.0gL -1 adipic acid by fed-batch fermentation. To the best of our knowledge, these results constitute the highest adipic acid titer reported in E. coli. Copyright © 2018. Published by Elsevier Inc.

  1. Adsorption of uranium ions by crosslinked polyester resin functionalized with acrylic acid from aqueous solutions

    International Nuclear Information System (INIS)

    Cemal Oezeroglu; Niluefer Metin

    2012-01-01

    In this paper, the crosslinked polyester resin containing acrylic acid functional groups was used for the adsorption of uranium ions from aqueous solutions. For this purpose, the crosslinked polyester resin of unsaturated polyester in styrene monomer (Polipol 353, Poliya) and acrylic acid as weight percentage at 80 and 20%, respectively was synthesized by using methyl ethyl ketone peroxide (MEKp, Butanox M60, Azo Nobel)-cobalt octoate initiator system. The adsorption of uranium ions on the sample (0.05 g copolymer and 5 mL of U(VI) solution were mixed) of the crosslinked polyester resin functionalized with acrylic acid was carried out in a batch reactor. The effects of adsorption parameters of the contact time, temperature, pH of solution and initial uranium(VI) concentration for U(VI) adsorption on the crosslinked polyester resin functionalized with acrylic acid were investigated. The adsorption data obtained from experimental results depending on the initial U(VI) concentration were analyzed by the Freundlich, Langmuir and Dubinin-Radushkevich (D-R) adsorption isotherms. The adsorption capacity and free energy change were determined by using D-R isotherm. The obtained experimental adsorption data depending on temperature were evaluated to calculate the thermodynamic parameters of enthalpy (ΔH o ), entropy (ΔS o ) and free energy change (ΔG o ) for the U(VI) adsorption on the crosslinked polyester resin functionalized with acrylic acid from aqueous solutions. The obtained adsorption data depending on contact time were analyzed by using adsorption models such as the modified Freundlich, Elovich, pseudo-first order and pseudo-second-order kinetic models. (author)

  2. Eco-friendly Crosslinking Agent for Acid Functional Acrylic Resin

    Directory of Open Access Journals (Sweden)

    Archana Shah

    2009-01-01

    Full Text Available Oil from J. multifida was extracted and it was first converted into N,N-bis(2-hydroxyethyl Jatropha fatty amide (HEJFA. HEJFA has been synthesized by reaction between Jatropha oil and diethanol amine in presence of zinc oxide as a catalyst. The reaction is relatively rapid and proceeded to high yield at 200±5 OC. The resulting HEJFA was used to formulate thermosetting coating compositions. Films were cured at ambient (air drying and elevated (stove drying temperatures using N, N-bis(2-hydroxyethyl Jatropha fatty amide (HEJFA as eco-friendly crosslinking agent for acrylic resin. The coating performance of the various compositions was tested by measurement of scratch hardness, impact strength and chemical resistance. The results show better performance of the HEJFA based compositions compared to butylated melamine formaldehyde (MF based compositions.

  3. Contribution To Degradation Study, Behavior Of Unsaturated Polyester Resin Under Neutron Irradiation

    Science.gov (United States)

    Abellache, D.; Lounis, A.; Taïbi, K.

    2010-01-01

    Applications of unsaturated polyester thermosetting resins are numerous in construction sector, in transport, electric spare parts manufactures, consumer goods, and anticorrosive materials. This survey reports the effect of thermosetting polymer degradation (unsaturated polyester): degradation by neutrons irradiation. In order to evaluate the deterioration of our material, some comparative characterizations have been done between standard samples and damaged ones. Scanning electron microscopy (SEM), ultrasonic scanning, hardness test (Shore D) are the techniques which have been used. The exposure to a neutrons flux is carried out in the column of the nuclear research reactor of Draria (Algiers-Algeria). The energetic profile of the incidental fluxes is constituted of fast neutrons (ΦR = 3.1012n.cm-2.s-1, E = 2 Mev) of thermal neutrons (ΦTH = 1013n.cm-2.s-1; E = 0.025 ev) and epithermal neutrons (Φepi = 7.1011 n.cm-2.s-1; E>4,9 ev). The received dose flow is 0,4 Kgy. We notice only a few scientific investigations can be found in this field. In comparison with the standard sample (no exposed) it is shown that the damage degree is an increasing process with the exposure. Concerning the description of irradiation effects on polymers, we can advance that several reactions are in competition : reticulation, chain break, and oxidation by radical mechanism. In our case the incidental particle of high energy fast neutrons whose energy is greater or equal to 2 Mev, is braked by the target with a nuclear shock during which the incidental particle transmits a part of its energy to an atom. If the energy transfer is sufficient, the nuclear shock permits to drive out an atom of its site the latter will return positioning interstitially, the energy that we used oversteps probably the energy threshold (displacement energy). This fast neutrons collision with target cores proceeds to an indirect ionization by the preliminary creation of excited secondary species that will

  4. Degradation by acetic acid for crystalline Si photovoltaic modules

    Science.gov (United States)

    Masuda, Atsushi; Uchiyama, Naomi; Hara, Yukiko

    2015-04-01

    The degradation of crystalline Si photovoltaic modules during damp-heat test was studied using some test modules with and without polymer film insertion by observing electrical and electroluminescence properties and by chemical analyses. Acetic acid generated by the hydrolysis decomposition of ethylene vinyl acetate used as an encapsulant is the main origin of degradation. The change in electroluminescence images is explained on the basis of the corrosion of electrodes by acetic acid. On the other hand, little change was observed at the pn junction even after damp-heat test for a long time. Therefore, carrier generation occurs even after degradation; however, such generated carriers cannot be collected owing to corrosion of electrodes. The guiding principle that module structure and module materials without saving acetic acid into the modules was obtained.

  5. Recovery of acid-degraded tributyl phosphate by solvent extraction

    International Nuclear Information System (INIS)

    Young, G.C.; Holladay, D.W.

    1981-01-01

    During nuclear fuel reprocessing the organic solvent becomes loaded with various acidic degradation products, which can be effectively removed through solvent extraction. Studies have been made with a small bench-scale solvent extraction system to optimize such parameters as pH of aqueous phase, phase ratio, residence time, flow rates, and temperature. The necessary decontamination factors have been obtained for various degradation products during continuous solvent extraction in one stage, with the aqueous phase being recycled. The aqueous phase contains compounds that can be degraded to gases to minimize waste disposal problems

  6. A degradation study of PLLA containing lauric acid.

    Science.gov (United States)

    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.

  7. Biophysical study of resin acid effects on phospholipid membrane structure and properties

    DEFF Research Database (Denmark)

    Jagalski, Vivien; Barker, Robert; Topgaard, Daniel

    2016-01-01

    Hydrophobic resin acids (RAs) are synthesized by conifer trees as part of their defense mechanisms. One of the functions of RAs in plant defense is suggested to be the perturbation of the cellular membrane. However, there is a vast diversity of chemical structures within this class of molecules......, and there are no clear correlations to the molecular mechanisms behind the RA's toxicity. In this study we unravel the molecular interactions of the three closely related RAs dehydroabietic acid, neoabietic acid, and the synthetic analogue dichlorodehydroabietic acid with dipalmitoylphosphatidylcholine (DPPC) model...... are correlated with the physical chemical properties of the RA and their toxicity....

  8. Activated sludge degradation of adipic acid esters.

    Science.gov (United States)

    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

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

    Directory of Open Access Journals (Sweden)

    C. L. P. S. Zanta

    2009-09-01

    Full Text Available In this study, advanced oxidation processes (AOPs such as the UV/H2O2 and Fenton processes were investigated for the degradation of 2-hydroxybenzoic acid (2-HBA in lab-scale experiments. Different [H2O2]/[2-HBA] molar ratios and pH values were used in order to establish the most favorable experimental conditions for the Fenton process. For comparison purposes, degradation of 2-HBA was carried out by the UV/H2O2 process under Fenton experimental conditions. The study showed that the Fenton process (a mixture of hydrogen peroxide and Fe2+ ion was the most effective under acidic conditions, leading to the highest rate of 2-hydroxybenzoic acid degradation in a very short time interval. This same process led to a six-fold acceleration of the oxidation rate compared with the UV/H2O2 process. The degradation of 2-hydroxybenzoic acid was found to follow first-order kinetics and to be influenced by the type of process and the experimental conditions. The experimental results showed that the most favorable conditions for 2-HBA degradation by the Fenton process are pH around 4-5, [Fe2+] = 0.6 mmol.L-1, and [H2O2]/[2-HBA] molar ratio = 7. The hydroxylation route is explained here for the two processes, and the results are discussed in the light of literature information.

  10. Sorption Efficiency of a New Sorbent towards Cadmium(II: Methylphosphonic Acid Grafted Polystyrene Resin

    Directory of Open Access Journals (Sweden)

    Nacer Ferrah

    2013-01-01

    Full Text Available A new chelating polymeric sorbent has been developed using polystyrene resin grafted with phosphonic acid. After characterization by FTIR and elementary analysis, the new resin has been investigated in liquid-solid extraction of cadmium(II. The results indicated that phosphonic resin could adsorb Cd(II ion effectively from aqueous solution. The adsorption was strongly dependent on the pH of the medium and the optimum pH value level for better sorption was between 3.2 and 5.2. The influence of other analytical parameters including contact time, amount of resin, metal ion concentration, and the presence of some electrolytes was investigated. The maximum uptake capacity of Cd(II ions was 37,9 mg·g−1 grafted resin at ambient temperature, at an initial pH value of 5.0. The overall adsorption process was best described by pseudo second-order kinetic. When Freundlich and Langmuir isotherms were tested, the latter had a better fit with the experimental data. Furthermore, more than 92% of Cd(II could be eluted by using 1.0 mol·L−1 HCl in one cycle.

  11. Simultaneous separation and detection of actinides in acidic solutions using an extractive scintillating resin.

    Science.gov (United States)

    Roane, J E; DeVol, T A

    2002-11-01

    An extractive scintillating resin was evaluated for the simultaneous separation and detection of actinides in acidic solutions. The transuranic extractive scintillating (TRU-ES) resin is composed of an inert macroporous polystyrene core impregnated with organic fluors (diphenyloxazole and 1,4-bis-(4-methyl-5-phenyl-2-oxazolyl)benzene) and an extractant (octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide in tributyl phosphate). The TRU-ES resin was packed into FEP Teflon tubing to produce a flow cell (0.2-mL free column volume), which is placed into a scintillation detection system to obtain pulse height spectra and time series data during loading and elution of actinides onto/from the resin. The alpha-particle absolute detection efficiencies ranged from 77% to 96.5%, depending on the alpha energy and quench. In addition to the on-line analyses, off-line analyses of the effluent can be conducted using conventional detection methods. The TRU-ES resin was applied to the quantification of a mixed radionuclide solution and two actual waste samples. The on-line characterization of the mixed radionuclide solution was within 10% of the reported activities whereas the agreement with the waste samples was not as good due to sorption onto the sample container walls and the oxidation state of plutonium. Agreement between the on-line and off-line analyses was within 35% of one another for both waste samples.

  12. MICROWAVE INDUCED DEGRADATION OF GLASS FIBER REINFORCED POLYESTER FOR FIBER AND RESIN RECOVERY

    DEFF Research Database (Denmark)

    Ucar, Hülya; Nielsen, Rudi Pankratz; Søgaard, Erik Gydesen

    A solvolysis process to depolymerize the resin in glass fiber reinforced composites and recover the glass fibers has been investigated using microwave induced irradiation. The depolymerization was carried out in HNO3 with concentrations in the range of 1M-7M and in KOH with concentrations ranging...... of depolymerization was achieved using KOH at concentrations ranging from 1-3.5M. Maximum 63 % resin removal was achieved using 1 M KOH and the resin removal efficiency decreased at higher KOH concentrations (3.5M). The glass fiber surfaces were damaged at both concentrations with more pronounced damages using 3.5M...... KOH. It was not possible to recover monomers using KOH....

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

    Science.gov (United States)

    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.

  14. Inhibition of platelet aggregation by diterpene acids from Pinus massoniana resin.

    Science.gov (United States)

    Cheung, H T; Fu, S L; Smal, M A

    1994-01-01

    The acidic fraction of the resin of Pinus massoniana Lamb. from China was converted to the p-nitrophenyl esters, and the esters separated by chromatography. The separated p-nitrophenyl esters were individually hydrolysed by potassium hydroxide in acetone-water at room temperature to 8 diterpene acids of the pimarane and abietane groups: pimaric acid (8(14),15-pimaradien-18-oic acid) (1), levopimaric acid (8(14),12-abietadien-18-oic acid) (2), palustric acid (8,13-abietadien-18-oic acid) (3), neobietic acid (8(14),13(15)-abietadien-18-oic acid) (4), abietic acid (7,13-abietadien-18-oic acid) (5), dehydroabietic acid (8,11,13-abietatrien-18-oic acid) (6), 7-oxodehydroabietic acid (7-oxo-8,11,13-abietatrien-18-oic acid) (7) and 7 alpha-hydroxydehydroabietic acid (7 alpha-hydroxy-8,11,13-abietatrien-18-oic acid) (8). The structure (and stereochemistry) of the diterpene acids were substantiated by nuclear magnetic resonance spectroscopy (proton and carbon-13, one and two dimensional), by mass spectrometry (electron impact and methane chemical ionization) and by rotation measurements. The 8 diterpene acids were tested for their ability to inhibit the aggregation of washed rabbit platelets induced by platelet activating factor (PAF), adenosine diphosphate (ADP) and by calcium ionophore A23187. With platelet aggregation induced by the latter two agonists, activities comparable with or higher than linolenic acid were given by the first 4 acids. With aggregation induced by PAF, the first 3 acids show activity, but at a level significantly lower than that of linolenic acid. Levopimaric acid has the highest activity among the diterpene acids tested. It is proposed that this activity is related to the folded shape of the molecule.

  15. Adsorption Equilibrium Equation of Carboxylic Acids on Anion-Exchange Resins in Water.

    Science.gov (United States)

    Kanazawa, Nobuhiro; Urano, Kohei; Kokado, Naohiro; Urushigawa, Yoshikuni

    2001-06-01

    The adsorption of propionic acid and benzoic acid on anion-exchange resins was analyzed, and an adsorption equilibrium equation of carboxylic acids was proposed. The adsorption of carboxylic acids on the anion-exchange resins was considered to be the sum of the physical adsorption of the molecule and the ion-exchange adsorption of the ion, which were independent of each other. For the physical adsorption of carboxylic acids, it was conformed to the Freundlich equation. For the ion-exchange adsorption of carboxylate ions, the equilibrium equation corresponded well with the experimental results for wide ranges of concentration and pH. The equation contains a selectivity coefficient S(A)(Cl) for the chloride ion versus the carboxylate ion, which was considered essentially a constant. The influent of the bicarbonate ion from carbon dioxide in air could also be expressed by the additional equilibrium equation with the selectivity coefficient S(HCO(3))(Cl) for the chloride ion versus the bicarbonate ion. Consequently, an adsorption equilibrium equation can estimate the equilibrium adsorption amounts. Even the effect of a coexisting bicarbonate ion is inconsequential when the parameters of the Freundlich isotherm equation and the selectivity coefficients of the carboxylate ion and the bicarbonate ion in each resin are determined in advance. Copyright 2001 Academic Press.

  16. Study of plutonium IV elution from macromolecular anion exchange resin by 0.5 M nitric acid

    International Nuclear Information System (INIS)

    Nadkarni, M.N.; Mayankutty, P.C.; Pillai, N.S.; Shinde, S.S.

    1976-01-01

    Preliminary studies indicated that macroreticular resins possess more or less the same capacities and absorption characteristics for thorium, uranium and plutonium from nitric acid solutions as the conventional resins. Detailed studies were, then, conducted. It was found that Pu(IV) can be loaded on the macroreticular anion exchange resin, Amberlyst A-26 from 7.2 M nitric acid in much the same way as Dowex 1x4. It was also observed that the elution of Pu(IV) from Amberlyst A-26 by 0.5 M nitric acid is much more rapid and quantitative than from Dowex 1x4. (author)

  17. Varying Conditions for Hexanoic Acid Degradation with BioTiger™

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-07-27

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

  18. Separation of aliphatic carboxylic acids and benzenecarboxylic acids by ion-exclusion chromatography with various cation-exchange resin columns and sulfuric acid as eluent.

    Science.gov (United States)

    Ohta, Kazutoku; Ohashi, Masayoshi; Jin, Ji-Ye; Takeuchi, Toyohide; Fujimoto, Chuzo; Choi, Seong-Ho; Ryoo, Jae-Jeong; Lee, Kwang-Pill

    2003-05-16

    The application of various hydrophilic cation-exchange resins for high-performance liquid chromatography (sulfonated silica gel: TSKgel SP-2SW, carboxylated silica gel: TSKgel CM-2SW, sulfonated polymethacrylate resin: TSKgel SP-5PW, carboxylated polymethacrylate resins: TSKgel CM-5PW and TSKgel OA-Pak A) as stationary phases in ion-exclusion chromatography for C1-C7 aliphatic carboxylic acids (formic, acetic, propionic, butyric, isovaleric, valeric, isocaproic, caproic, 2-methylhexanoic and heptanoic acids) and benzenecarboxylic acids (pyromellitic, trimellitic, hemimellitic, o-phthalic, m-phthalic, p-phthalic, benzoic, salicylic acids and phenol) was carried out using diluted sulfuric acid as the eluent. Silica-based cation-exchange resins (TSKgel SP-2SW and TSKgel CM-2SW) were very suitable for the ion-exclusion chromatographic separation of these benzenecarboxylic acids. Excellent simultaneous separation of these benzenecarboxylic acids was achieved on a TSKgel SP-2SW column (150 x 6 mm I.D.) in 17 min using a 2.5 mM sulfuric acid at pH 2.4 as the eluent. Polymethacrylate-based cation-exchange resins (TSKgel SP-5PW, TSKgel CM-5PW and TSKgel OA-Pak A) acted as advanced stationary phases for the ion-exclusion chromatographic separation of these C1-C7 aliphatic carboxylic acids. Excellent simultaneous separation of these C1-C7 acids was achieved on a TSKgel CM-5PW column (150 x 6 mm I.D.) in 32 min using a 0.05 mM sulfuric acid at pH 4.0 as the eluent.

  19. Kinetics of Ascorbic acid degradation in asceptically packaged ...

    African Journals Online (AJOL)

    The recent ban on importation of fruit juices into Nigeria led to increase in production of locally - made orange juice. Degradation kinetics of ascorbic acid at refrigeration (70C ± 20C) and ambient temperature (280C ± 20C) were evaluated by the application of zero-order reaction kinetic. Results showed satisfactory ...

  20. Eicosapentaenoic acid and docosahexaenoic acid increase the degradation of amyloid-β by affecting insulin-degrading enzyme.

    Science.gov (United States)

    Grimm, Marcus O W; Mett, Janine; Stahlmann, Christoph P; Haupenthal, Viola J; Blümel, Tamara; Stötzel, Hannah; Grimm, Heike S; Hartmann, Tobias

    2016-12-01

    Omega-3 polyunsaturated fatty acids (PUFAs) have been proposed to be highly beneficial in Alzheimer's disease (AD). AD pathology is closely linked to an overproduction and accumulation of amyloid-β (Aβ) peptides as extracellular senile plaques in the brain. Total Aβ levels are not only dependent on its production by proteolytic processing of the amyloid precursor protein (APP), but also on Aβ-clearance mechanisms, including Aβ-degrading enzymes. Here we show that the omega-3 PUFAs eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) increase Aβ-degradation by affecting insulin-degrading enzyme (IDE), the major Aβ-degrading enzyme secreted into the extracellular space of neuronal and microglial cells. The identification of the molecular mechanisms revealed that EPA directly increases IDE enzyme activity and elevates gene expression of IDE. DHA also directly stimulates IDE enzyme activity and affects IDE sorting by increasing exosome release of IDE, resulting in enhanced Aβ-degradation in the extracellular milieu. Apart from the known positive effect of DHA in reducing Aβ production, EPA and DHA might ameliorate AD pathology by increasing Aβ turnover.

  1. Bonding effectiveness of self-adhesive and conventional-type adhesive resin cements to CAD/CAM resin blocks. Part 2: Effect of ultrasonic and acid cleaning.

    Science.gov (United States)

    Kawaguchi, Asuka; Matsumoto, Mariko; Higashi, Mami; Miura, Jiro; Minamino, Takuya; Kabetani, Tomoshige; Takeshige, Fumio; Mine, Atsushi; Yatani, Hirofumi

    2016-01-01

    The present study assessed the effect of ultrasonic and acid cleaning on resin cement bonding to CAD/CAM resin blocks. One of two resin cements, PANAVIA V5 (PV5) or PANAVIA SA CEMENT HANDMIX (PSA), were bonded to one of 24 CAD/CAM blocks (KATANA AVENCIA BLOCK). Each cement group was divided into four subgroups: no cleaning (Ctl), ultrasonic cleaning (Uc), acid cleaning (Ac) and Uc+Ac. Micro-tensile bond strengths (µTBSs) were measured immediately and 1, 3, and 6 months after water storage. Block surfaces after each treatment were analyzed by scanning electron microscopy. Analysis of variance revealed a statistically significant effect for the parameters 'surface treatment' (p<0.001, F=40), 'resin cement' (p<0.001, F=696) and 'water aging' (p<0.001, F=71). The PV5 group exhibited higher µTBS values than the PSA group. Although cleaning after sandblasting was effective in removing residual alumina particles, it did not affect the long-term bonding durability with non-contaminated CAD/CAM resin blocks.

  2. Aminolysis of resin-bound N-nosylaziridine-2-carboxylic acids

    DEFF Research Database (Denmark)

    Olsen, Christian A; Christensen, Caspar; Nielsen, Birgitte

    2006-01-01

    [Structure: see text] Solid-phase synthesis is a rapidly developing area of organic chemistry, of particular importance for medicinal chemistry and chemical biology. Aziridines have previously only rarely been applied in solid-phase synthesis. In the present work, aminolysis of resin-bound, spring......-loaded N-nitrobenzenesulfonyl-activated aziridine-2-carboxylic acids has been optimized and employed in the synthesis of a number of open-chain and heterocyclic scaffolds, including enantiopure products....

  3. Molecular screening of wine lactic acid bacteria degrading hydroxycinnamic acids.

    Science.gov (United States)

    de las Rivas, Blanca; Rodríguez, Héctor; Curiel, José Antonio; Landete, José María; Muñoz, Rosario

    2009-01-28

    The potential to produce volatile phenols from hydroxycinnamic acids was investigated for lactic acid bacteria (LAB) isolated from Spanish grape must and wine. A PCR assay was developed for the detection of LAB that potentially produce volatile phenols. Synthetic degenerate oligonucleotides for the specific detection of the pdc gene encoding a phenolic acid decarboxylase were designed. The pdc PCR assay amplifies a 321 bp DNA fragment from phenolic acid decarboxylase. The pdc PCR method was applied to 85 strains belonging to the 6 main wine LAB species. Lactobacillus plantarum, Lactobacillus brevis, and Pediococcus pentosaceus strains produce a positive response in the pdc PCR assay, whereas Oenococcus oeni, Lactobacillus hilgardii, and Leuconostoc mesenteroides strains did not produce the expected PCR product. The production of vinyl and ethyl derivatives from hydroxycinnamic acids in culture media was determined by high-performance liquid chromatography. A relationship was found between pdc PCR amplification and volatile phenol production, so that the LAB strains that gave a positive pdc PCR response produce volatile phenols, whereas strains that did not produce a PCR amplicon did not produce volatile phenols. The proposed method could be useful for a preliminary identification of LAB strains able to produce volatile phenols in wine.

  4. Screening Analyses of Pinosylvin Stilbenes, Resin Acids and Lignans in Norwegian Conifers

    Directory of Open Access Journals (Sweden)

    Anne Fiksdahl

    2006-01-01

    Full Text Available The content and distribution of stilbenes and resin acids in Scots pine (Pinus sylvestris and spruce (Picea abies, sampled in central Norway, have been examined. The contents of pinosylvin stilbenes in pine heartwood/living knots were 0.2-2/2-8 % (w/w. No stilbenes could be detected in spruce (Picea abies. The resin acid contents of pine sapwood/heartwood and knots were 1-4 and 5-10 % (w/w, respectively. Minor amounts of resin acids (< 0.2/< 0.04 %w/w were identified in spruce wood/knots. The lignan content in knots of Norwegian spruce was 6.5 % (w/w. Diastereomerically pure hydroxymatairesinol (HMR, 84 % of total lignans was readily isolated from this source since only minor quantities (2.6 % of total lignans of the allo-HMR diastereomer was detected. Insignificant amounts of lignans were present in the sapwood. Lignans could not be detected in the sapwood or knots of Norwegian sallow (Salix caprea, birch (Betula pendula or juniper (Juniperus communis.

  5. Removing and recovering of uranium from the acid mine waters by using ion exchange resin

    International Nuclear Information System (INIS)

    Nascimento, Marcos Roberto Lopes do

    1998-01-01

    Ion exchange using resins is one of the few processes capable of reducing ionic contaminants in effluents to very low levels. In this study the process was used to remove and recovery uranium from acid mine waters at Pocos de Caldas-MG Uranium Mining and Milling Plant. The local mineralogical features, allied to the biogeochemical phenomena, owing to presence of pyrite in the rock piles, moreover another factors, resulting acid drainage with several pollutants, including uranium ranging from 6 to 14 mg/l, as sulfate complex, that can be removed by anionic exchanger. The iron interference is eliminated by lime pretreatment of water, increasing pH from 2.6 to 3.3-3.8 to precipitate this cation, without changing the uranium amount. Eight anionic resins were tested, based on the uranium loading, in sorption studies. Retention time, and pH influence was verified for the exchanger chose. With breakthrough of 1 mg U/L and 10 mg U/l in the feed solution, the uranium decontamination level was 94%. Typical values of loading resin were 20-30 g U/l and 70-90 g SO 4 /l. Uranium elution was done with Na Cl solution. Retention time, saline, and acid concentration were the parameters studied. The concentrate, obtained from the eluate by ammonia precipitation, presented uranium (86,8% as U 3 O 8 ) and impurities within commercial specifications. (author)

  6. Synthesis of iminodi(methylphosphonic acid)-type chitosan resin and its adsorption behavior for trace metals

    International Nuclear Information System (INIS)

    Yamakawa, Satoko; Oshita, Koji; Sabarudin, Akhmad; Oshima, Mitsuko; Motomizu, Shoji

    2004-01-01

    A chitosan-based resin possessing the iminodi(methyphosphonic acid) moiety (IDP-type chitrosan resin) was synthesized by using cross-linked chitosan as a base material. The adsorption behavior of trace metal ions on the IDP-type chitosan resin was systematically investigated using a mini-column (1 ml of the resin) packed with the resin. The concentrations of metal ions in the effluents were measured by ICP-MS and ICP-AES. The resin could adsorb four metals, such as In(III), Sn(II), Th(IV), and U(VI), by almost 100% over a wide pH range (1-7). Uranium(VI) and thorium could not be eluted with nitric acid and hydrochloric acid (1-6 M); other metal ions were easily and readily eluted with 1 M nitric acid. The IDP-type chitosan resin synthesized in this work can be applied to the separation of U(VI) and Th(IV) from other metal ions. (author)

  7. The application of macroporous resins in the separation of licorice flavonoids and glycyrrhizic acid.

    Science.gov (United States)

    Fu, Boqiang; Liu, Jie; Li, Huan; Li, Lei; Lee, Frank S C; Wang, Xiaoru

    2005-09-30

    Glycyrrhizic acid (GA) and licorice flavonoids (LF) are the two classes of bioactive components in licorice with known pharmacological effects. But long-term excessive intake of GA may cause sodium retention and hypertension. In this study, the performance and adsorption characteristics of four widely used macroporous resins for the separation of deglycyrrhizinated, flavonoids enriched licorice has been critically evaluated. The sorption and desorption properties of LF and GA on macroporous resins including XDA-1, LSA-10, D101 and LSA-20 have been compared. The adsorption capacity was found to depend strongly on the pH of the feed solution. XDA-1 offers much higher adsorption capacity for GA and LF than other resins, and its adsorption data fit the best to the Freundlich isotherm. XDA-1 also shows much higher adsorption affinity towards LF than that of GA based on calculated results from the measured adsorption isotherms. Dynamic adsorption and desorption experiments have been carried out on a XDA-1 resin packed column to obtain optimal parameters for separating GA and LF. An enriched LF extract (about 21.9% purity) free of GA, and an enriched GA extract with 66% purity can be separated from crude licorice extract in one run.

  8. Effect of humic acid on ciprofloxacin removal by magnetic multifunctional resins

    Science.gov (United States)

    Wang, Wei; Cheng, Jiade; Jin, Jing; Zhou, Qing; Ma, Yan; Zhao, Qingqing; Li, Aimin

    2016-07-01

    Background organic matter significantly influences the removal of emerging contaminants in natural water. In this work, the adsorption of ciprofloxacin (CPX) onto a series of magnetic multifunctional resins (GMA10-GMA90) in the presence and absence of humic acid (HA) was conducted to demonstrate the effect of HA. Both hydrophobic and ion exchange interactions contributed to CPX adsorption. Negative charge-assisted hydrogen bonds also participated in the adsorption process, resulting in the high adsorption amount of anionic CPX onto the negatively charged GMA30 under basic solutions. HA could impact CPX adsorption not only as a competitive adsorbate but also as an additional adsorbent. At pH 5.6, the additional adsorption sites provided by adsorbed HA molecules on the resins dominated and thus facilitated the adsorption process. While at pH 10, HA inhibited the adsorption of CPX by directly competing for ion exchange sites and coexisting with CPX in the solution. The ratio of the amount of CPX adsorbed by dissolved HA to that by the resin reached as high as 1.61 for GMA90. The adsorbed HA molecules onto the resins could provide additional adsorption sites for CPX as proven by the enhanced CPX adsorption in HA-preloading systems at pH 5.6.

  9. SPE and HPLC/UV of resin acids in colophonium-containing products.

    Science.gov (United States)

    Nilsson, Ulrika; Berglund, Naghmeh; Lindahl, Fredrik; Axelsson, Sara; Redeby, Theres; Lassen, Pia; Karlberg, Ann-Therese

    2008-08-01

    A new method, involving SPE and HPLC/UV diode-array detection (DAD), was developed for the quantification of colophonium components in different consumer products, such as cosmetics. Colophonium is a common cause of contact dermatitis since its components can oxidize into allergens on exposure to air. Three different resin acids were used as markers for native and oxidized colophonium, abietic acid (AbA), dehydroabietic acid (DeA), and 7-oxodehydroabietic acid (7-O-DeA). The SPE method, utilizing a mixed-mode hydrophobic and anion exchange retention mechanism, was shown to yield very clean extracts. The use of a urea-embedded C(12) HPLC stationary phase improved the separation of the resin acids compared to common C(18). Concentrations higher than 2 mg/g of both AbA and DeA were detected in wax strips. In this product also 7-O-DeA, a marker for oxidized colophonium, was detected at a level of 28 microg/g. The LODs were in the range of 7-19 microg/g and the LOQs 22-56 microg/g. The method is simple to use and can be applied on many types of technical products, not only cosmetics. For the first time, a method for technical products was developed, which separates AbA from pimaric acid.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  12. Electrochemical degradation of clofibric acid in water by anodic oxidation

    International Nuclear Information System (INIS)

    Sires, Ignasi; Cabot, Pere Lluis; Centellas, Francesc; Garrido, Jose Antonio; Rodriguez, Rosa Maria; Arias, Conchita; Brillas, Enric

    2006-01-01

    Aqueous solutions containing the metabolite clofibric acid (2-(4-chlorophenoxy)-2-methylpropionic acid) up to close to saturation in the pH range 2.0-12.0 have been degraded by anodic oxidation with Pt and boron-doped diamond (BDD) as anodes. The use of BDD leads to total mineralization in all media due to the efficient production of oxidant hydroxyl radical (·OH). This procedure is then viable for the treatment of wastewaters containing this compound. The effect of pH, apparent current density, temperature and metabolite concentration on the degradation rate, consumed specific charge and mineralization current efficiency has been investigated. Comparative treatment with Pt yields poor decontamination with complete release of stable chloride ion. When BDD is used, this ion is oxidized to Cl 2 . Clofibric acid is more rapidly destroyed on Pt than on BDD, indicating that it is more strongly adsorbed on the Pt surface enhancing its reaction with ·OH. Its decay kinetics always follows a pseudo-first-order reaction and the rate constant for each anode increases with increasing apparent current density, being practically independent of pH and metabolite concentration. Aromatic products such as 4-chlorophenol, 4-chlorocatechol, 4-chlororesorcinol, hydroquinone, p-benzoquinone and 1,2,4-benzenetriol are detected by gas chromatography-mass spectrometry (GC-MS) and reversed-phase chromatography. Tartronic, maleic, fumaric, formic, 2-hydroxyisobutyric, pyruvic and oxalic acids are identified as generated carboxylic acids by ion-exclusion chromatography. These acids remain stable in solution using Pt, but they are completely converted into CO 2 with BDD. A reaction pathway for clofibric acid degradation involving all these intermediates is proposed

  13. Design and synthesis of bio-based UV curable PU acrylate resin from itaconic acid for coating applications.

    Science.gov (United States)

    Patil, Deepak M; Phalak, Ganesh A; Mhaske, S T

    2017-01-01

    UV curable PUA resin was successfully synthesized from polyol based on sustainable resource originated from itaconic acid (IA), isophorone diisocyanate (IPDI) and 2-hydroxyethyl methacrylate (HEMA). A polyol was synthesized by condensation reaction of IA with 16-hexanediol in the presence of p-Toluenesulfonic acid (pTSA). The synthesized PUA resin was characterized for its structural elucidation by using Fourier Transform Infrared Spectrophotometer (FTIR), 1 H and 13 C NMR spectroscopy. The synthesized UV curable PUA resin was incorporated in varying concentrations in conventional PUA coating system. The effects of varying concentration of synthesized UV curable PUA resin on rheology, crystallinity, thermal and coating properties were evaluated. The rheological behavior of the resins were evaluated at variable stress and result showed decrease in viscosity of resin as concentration of synthesized UV curable PUA resin increases in conventional PUA resin. The cured coatings have been evaluated for glass transition temperature ( T g ) and thermal behavior by differential scanning calorimeter and thermogravimetric analysis respectively. The degree of crystallinity of the coatings was determined from X-ray diffraction patterns using the PFM program. It was found that increase in the mass proportion of IA based PUA in coatings, the coating becomes more rigid and crystalline. The synthesized UV curable PUA coatings showed interesting mechanical, chemical, solvent and thermal properties as compared to the conventional PUA. Further, cured coatings were also evaluated for gel content and water absorption.

  14. Color degradation of acrylic resin denture teeth as a function of liquid diet: ultraviolet-visible reflection analysis.

    Science.gov (United States)

    Hipólito, Ana Carolina; Barão, Valentim A; Faverani, Leonardo P; Ferreira, Mayara B; Assunção, Wirley G

    2013-10-01

    The effect of different beverages on acrylic resin denture teeth color degradation is evaluated. Ten acrylic resin denture teeth brands were evaluated: Art Plus (AP), Biolux (BX), Biotone IPN (BI), Magister (MG), Mondial 6 (MD), Premium 6 (PR), SR Vivodent PE (SR), Trilux (TR), Trubyte Biotone (TB), and Vipi Dent Plus (VP). Teeth were immersed in staining solutions (coffee, cola, and orange juice) or artificial saliva (control) (n=6) for 1, 7, 15, or 30 days. Specimen colors were evaluated spectrophotometrically based on the Commission Internationale d'Eclairage L*a*b* system. Color differences (ΔE) were calculated between the baseline and post-staining results. Data were evaluated by analysis of variance and Tukey test (α = 0.05). BI (1.82 ± 0.95) and TR (1.78 ± 0.72) teeth exhibited the greatest ΔE values, while BX (0.88 ± 0.43) and MD (1.09 ± 0.44) teeth were the lowest, regardless of solution and measurement period, and were different from BI and TR teeth (P denture teeth color alterations than orange juice and saliva (P denture teeth color alterations. Greater immersion times caused higher denture teeth color changes. The lifespan of removable dentures and the aesthetic satisfaction of several edentulous patients may be increased with the use of stain-resistant artificial denture teeth.

  15. The Use of Commercial Non-Hazardous Air Pollutant Monomers to Optimize the Properties of Fatty Acid-Based Resins

    Science.gov (United States)

    2009-05-01

    It was found that cyclohexyl methacrylate (CHMA) was the most effective reactive diluent in replacing methacrylated lauric acid (MLau) because it...The reaction of glycidyl methacrylate and lauric acid to produce the MLau monomer... acid -based monomers to be used as the reactive diluent in VE resins (9, 10). Figure 1 depicts the synthetic route used to form methacrylated lauric

  16. Biogenic glutamic acid-based resin: Its synthesis and application in the removal of cobalt(II)

    Energy Technology Data Exchange (ETDEWEB)

    Jamiu, Zakariyah A.; Saleh, Tawfik A.; Ali, Shaikh A., E-mail: shaikh@kfupm.edu.sa

    2017-04-05

    Highlights: • A novel resin embedded with metal chelating glutamic acid was synthesized. • The biogenic amino acid residues imparted remarkable efficacy to remove Co(II). • The resin showed excellent ability to remove various metals from wastewater. - Abstract: Inexpensive biogenic glutamic acid has been utilized to synthesize a cross-linked dianionic polyelectrolyte (CDAP) containing metal chelating ligands. Cycloterpolymerization, using azoisobutyronitrile as an initiator, of N,N-diallylglutamic acid hydrochloride, sulfur dioxide and a cross-linker afforded a pH-responsive cross-linked polyzwitterionic acid (CPZA) which upon basification with NaOH was converted into CDAP. The new resin, characterized by a multitude of spectroscopic techniques as well as Scanning Electron Microscopy (SEM) and Brunauer–Emmett–Teller (BET) analyses, was evaluated for the removal of Co(II) as a model case under different conditions. The adsorption capacity of 137 mg g{sup −1} does indeed make the resin as one of the most effective sorbents in recent times. The resin leverages its cheap natural source and ease of regeneration in combination with its high and fast uptake capacities to offer a great promise for wastewater treatment. The resin has demonstrated remarkable efficiency in removing toxic metal ions including arsenic from a wastewater sample.

  17. Biogenic glutamic acid-based resin: Its synthesis and application in the removal of cobalt(II)

    International Nuclear Information System (INIS)

    Jamiu, Zakariyah A.; Saleh, Tawfik A.; Ali, Shaikh A.

    2017-01-01

    Highlights: • A novel resin embedded with metal chelating glutamic acid was synthesized. • The biogenic amino acid residues imparted remarkable efficacy to remove Co(II). • The resin showed excellent ability to remove various metals from wastewater. - Abstract: Inexpensive biogenic glutamic acid has been utilized to synthesize a cross-linked dianionic polyelectrolyte (CDAP) containing metal chelating ligands. Cycloterpolymerization, using azoisobutyronitrile as an initiator, of N,N-diallylglutamic acid hydrochloride, sulfur dioxide and a cross-linker afforded a pH-responsive cross-linked polyzwitterionic acid (CPZA) which upon basification with NaOH was converted into CDAP. The new resin, characterized by a multitude of spectroscopic techniques as well as Scanning Electron Microscopy (SEM) and Brunauer–Emmett–Teller (BET) analyses, was evaluated for the removal of Co(II) as a model case under different conditions. The adsorption capacity of 137 mg g −1 does indeed make the resin as one of the most effective sorbents in recent times. The resin leverages its cheap natural source and ease of regeneration in combination with its high and fast uptake capacities to offer a great promise for wastewater treatment. The resin has demonstrated remarkable efficiency in removing toxic metal ions including arsenic from a wastewater sample.

  18. Esterification of palm fatty acid distillate with epychlorohydrin using cation exchange resin catalyst

    Science.gov (United States)

    Budhijanto, Budhijanto; Subagyo, Albertus F. P. H.

    2017-05-01

    Palm Fatty Acid Distillate (PFAD) is one of the wastes from the conversion of crude palm oil (CPO) into cooking oil. The PFAD is currently only utilized as the raw material for low grade soap and biofuel. To improve the economic value of PFAD, it was converted into monoglyceride by esterification process. Furthermore, the monoglyceride could be polymerized to form alkyd resin, which is a commodity of increasing importance. This study aimed to propose a kinetics model for esterification of PFAD with epichlorohydrin using cation exchange resin catalyst. The reaction was the first step from a series of reactions to produce the monoglyceride. In this study, the reaction between PFAD and epichlorohydirne was run in a stirred batch reactor. The stirrer was operated at a constant speed of 400 RPM. The reaction was carried out for 180 minutes on varied temperatures of 60°C, 70°C, 80°C, dan 90°C. Cation exchange resin was applied as solid catalysts. Analysis was conducted periodically by measuring the acid number of the samples, which was further used to calculate PFAD conversion. The data were used to determine the rate constants and the equilibrium constants of the kinetics model. The kinetics constants implied that the reaction was reversible and controlled by the intrinsic surface reaction. Despite the complication of the heterogeneous nature of the reaction, the kinetics data well fitted the elementary rate law. The effect of temperature on the equilibrium constants indicated that the reaction is exothermic.

  19. Biodiesel production from acid oils and ethanol using a solid basic resin as catalyst

    International Nuclear Information System (INIS)

    Marchetti, J.M.; Errazu, A.F.

    2010-01-01

    In the search of an alternative fuel to substitute diesel fuel, biodiesel appears as one of the most promising sources of energy for diesel engines because of its environmental advantages and also due to the evolution of the petroleum market. Refined oil is the conventional raw material for the production of this biofuel; however, its major disadvantage is the high cost of its production. Therefore, frying oils, waste oils, crude oils and/or acid oils are being tested as alternative raw materials; nevertheless, there will be some problems if a homogeneous basic catalyst (NaOH) is employed due to the high amount of free fatty acid present in the raw oil. In this work, the transesterification reaction of acid oil using solid resin, Dowex monosphere 550 A, was studied as an alternative process. Ethanol was employed to have a natural and sustainable final product. The reaction temperature's effects, the initial amount of free fatty acid, the molar ratio of alcohol/oil and the type of catalyst (homogeneous or heterogeneous) over the main reaction are analyzed and their effects compared. The results obtained show that the solid resin is an alternative catalyst to be used to produce fatty acid ethyl esters (FAEEs) by a transesterification reaction with a final conversion over 90%. On the other hand, the time required to achieve this conversion is bigger than the one required using conventional technology which employs a homogeneous basic catalyst. This reaction time needs to be optimized. (author)

  20. Synthesis and Characterization of Dimmer-Acid-Based Nonisocyanate Polyurethane and Epoxy Resin Composite

    Directory of Open Access Journals (Sweden)

    Xin He

    2017-11-01

    Full Text Available In this study, dimmer-acid-based hybrid nonisocyanate polyurethanes (HNIPUs were synthesized by the one-step method without catalyst. Three polyamines and two epoxy resins were selected as raw materials for HNIPU, and cyclic carbonate was synthesized based on our previous work. All of the products were characterized by Fourier transform infrared spectroscopy (FTIR, differential scanning calorimetry (DSC, thermogravimetric analysis (TGA and dynamic mechanical analysis (DMA. Then, HNIPU coatings were prepared and determined by swelling, water absorption, and water contact angle. The results showed that the HNIPU-4551 have the best mechanical and thermal properties because of its high crosslinking density. Among the different amines, it was confirmed that tetraethylenepentamine was the best amine curing agent for HNIPU coating. Meanwhile, the epoxy resin with a higher epoxy value would also form a higher crosslinking density. Those coatings showed an excellent impact strength, adhesion, flexibility, pencil hardness, hydrophilic, and appropriate crosslinking density.

  1. Uranium(VI) adsorption properties of a chelating resin containing polyamine-substituted methylphosphonic acid moiety

    International Nuclear Information System (INIS)

    Matsuda, Masaaki; Akiyoshi, Yoshirou

    1991-01-01

    Uranium(VI) adsorption and desorption properties of a chelating resin containing polyamine-substituted methylphosphonic acid moiety of 2.29 mmol/g-resin (APA) were examined. Uranium(VI) adsorption properties of several ion exchange resins and extractant agents which were known as excellent adsorbents for uranium(VI), were examined together for a comparison with those of APA. Uranium(VI) adsorption capacity of APA at the concentration of 100 mg·dm -3 -uranium(VI) in 100 g·dm -3 -H 2 SO 4 aq. soln., 190 g·dm -3 -H 3 PO 4 aq. soln. and uranium enriched sea water, was 0.2, 0.05 and 0.05 mmol·g -1 respectively. The adsorption capacity of APA for uranium(VI) in these solutions was larger than that of another adsorbents, except the adsorption of uranium(VI) in enriched sea water on ion exchange resin containing phosphoric acid moiety (adsorption capacity ; 0.2 mmol·g -1 ). Uranium(VI) adsorption rate on APA was high and the relation between treatment time (t : min) and uranium(VI) concentration (y : mg·dm -3 ) in 100 g·dm -3 H 2 SO 4 aq. soln. after treatment, was shown as following equation, y=20 0.048t+1.90 (0≤t≤30). The adsorbed uranium(VI) on APA was able to be eluted with a mixed aq. soln. of hydrogen peroxide and sodium hydroxide and also was able to be eluted with an aq. alkaline soln. dissolved reduction agents such as sodium sulfite and hydrazine. From these results, it was thought that uranium(VI) adsorbed on APA was eluted due to the reduction to uranium(VI) by these eluents. (author)

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

    Science.gov (United States)

    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

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

    Directory of Open Access Journals (Sweden)

    Shaohua Chen

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

  4. Adsorption of beta-naphthalenesulfonic acid/sulfuric acid from their solution by weakly basic resin: equilibrium.

    Science.gov (United States)

    Li, Chang-Hai; Si, Peng-Fei

    2005-01-01

    Experiments for single and bisolute competitive adsorption were carried out to investigate the adsorption behavior of beta-naphthalenesulfonic acid (NSA) and sulfuric acid (H2SO4) from their solution at 25 degrees C onto weakly basic resin D301R. Adsorption affinity of sulfuric acid on D301R was found to be much higher than that of NSA. The data of single-solute adsorption were fitted to the Langmuir model and the Freundlich adsorption model. The ideal adsorbed solution theory (IAST) coupled with the single-solute adsorption models were used to predict the bisolute competitive adsorption equilibria. The IAST coupled with the Langmuir and the Freundlich model for sulfuric acid and NSA, respectively, yields the favorable representation of the bisolute competitive adsorption behavior.

  5. Photoelectrocatalytic degradation of benzoic acid using immobilized tungsten trioxide photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-11-01

    The thin films of WO{sub 3} were deposited with different solution quantities using chemical spray pyrolysis technique. The WO{sub 3} film thickness effect on the photoelectrochemical, structural, morphological and optical properties is studied. Polycrystalline, monoclinic WO{sub 3} films possess photoelectrochemical performance having onset potentials around +0.3 V/SCE in 0.01 M HClO{sub 4}. The maximum photocurrent density (I{sub ph} = 635 μA/cm{sup 2}) is observed for the film deposited with 75 ml solution quantity. The FE-SEM image shows compact structure with petals like morphology. The estimated indirect band gap of WO{sub 3} films lies in the range of 2.60–2.65 eV. The photoelectrocatalytic degradation of benzoic acid is studied using WO{sub 3} photoelectrode under UV light illumination and 57 ± 3% removal of benzoic acid is achieved. The mineralization of benzoic acid in aqueous solution has been studied by measuring COD values. - Highlights: • The photoactivity of sprayed tungsten trioxide (WO{sub 3}) thin film. • Structural analysis of WO{sub 3} thin films. • Photoelectrocatalytic and photocatalytic degradation of benzoic acid. • Reaction kinetics and mineralization of pollutants by COD.

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

    Science.gov (United States)

    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

  7. Evaluation and improvement of gamma-ray stability of chelating resins containing oxy-acid groups of phosphorus

    International Nuclear Information System (INIS)

    Jyo, Akinori; Yamabe, Kazunori; Shuto, Taketomi

    1998-01-01

    Chelating resins containing oxy-acid groups of phosphorus, such as phosphonic and phosphoric acid groups have been studied from the point of view of solvent extraction processes for the separation of nuclear fuel elements as well as of fission product ones. The present work was planned to evaluate the effect of gamma-ray on properties of the resins and to obtain directional information for design of the resins having high stability to gamma-ray. It was clarified that gamma-ray stability of the resins is not high; tolerance limit is ca. 2.3x10 3 C/kg. The present work also clarified that polymers crosslinked with divinylbenzene have much higher gamma-ray stability than ones crosslinked with dimetacrylate esters of oligo (ethylene glycol)s. (J.P.N.)

  8. Application of 10% Ascorbic Acid Improves Resin Shear Bond Stregth in Bleached Dentin

    Directory of Open Access Journals (Sweden)

    Kamizar Kamizar

    2014-10-01

    Full Text Available Normal 0 false false false IN X-NONE X-NONE MicrosoftInternetExplorer4 Restoration of the teeth immediately after bleaching with H2O2 35% is contraindicated due to the remnants of free radical that will stay inside dentin for 2-3 weeks which will compromise the adhesiveness of composite resin. Objective: The aim of this study was to evaluate the influence of 10% ascorbic acid on shear bond strength of composite placed on bleached dentin. Methods:Twenty seven samples were divided equally into three groups. Group 1: dentin was etched with 35% phosphoric acid; Group 2: dentin was bleached with 35% H2O2 followed by etching with 35% phosphoric acid; Group 3: dentin was bleached with 35% H2O2, followed by application of 10% ascorbic acid and etched with 35% phosphoric acid. All samples were then stored at 370C for 24 hours. The Universal Testing Machine was used to measure shear bond strength and the results were analyzed with Kruskal Wallis and Mann Whitney test. Results: After nine independent experiments, 10% ascorbic acid application on bleached dentin resulted in highest increased in bond stregth (56.04±11.06MPa compared to Group 2 (29.09±7.63MPa and Group 1 (25.55±2.22MPa and the difference was statistically significant (p<0.05. Conclusion: Application of 10% ascorbic acid to the bleached dentin improved the shear bond strength of resin composite.

  9. Uranium adsorption from the sulphuric acid leach liquor containing more chlorides with cation-exchange resin SL-406

    International Nuclear Information System (INIS)

    Hu Jun; Wang Zhaoguo; Chi Renqing; Niu Xuejun

    1994-01-01

    The feasibility of uranium adsorption was studied from the sulphuric acid leach liquor of a uranium ore containing more chlorides with cation-exchange resin SL-406. The influence of some factors on uranium adsorption was investigated. It was shown that the resin possesses better selectivity, stability and higher capacity. It can be effectively used to recovery uranium from leach liquors of uranium ores containing more chlorides

  10. Effect of Hydrofluoric Acid Concentration on Resin Adhesion to a Feldspathic Ceramic.

    Science.gov (United States)

    Venturini, Andressa Borin; Prochnow, Catina; Rambo, Dagma; Gundel, Andre; Valandro, Luiz Felipe

    2015-08-01

    To evaluate the effect of different concentrations of hydrofluoric acid (HF) on the contact angle and the resin bond strength durability to feldspathic ceramic. To evaluate the contact angles of distilled water on etched feldspathic ceramic, 25 specimens (12×10×2.4 mm) of VitaBlocks Mark II were used, divided into 5 groups (n=5): one unconditioned control (UC) group with no ceramic surface treatment, and 4 other groups that were etched for 60 s with different concentrations of HF: 1% (HF1), 3% (HF3), 5% (HF5) and 10% (HF10). The bond testing utilized 40 ceramic blocks (12×10×4 mm) that were fabricated and subjected to the same surface treatments as previously mentioned (excluding the control). The etched surfaces were silanized and resin cement was applied. After 24 h, the blocks were sectioned to produce bar specimens that were divided into two groups, non-aged (immediate testing) and aged (storage for 230 days+12,000 thermocycles at 5°C and 55°C), and subjected to microtensile testing (μTBS). Micromorphogical analysis of the treated surfaces was also performed (atomic force and scanning electron microscopy). One-way ANOVA and Tukey's tests were applied for data analysis. UC had the highest contact angle (61.4°), whereas HF10 showed the lowest contact angle (17.5°). In non-aged conditions, different acids promoted statistically similar bond strengths (14.2 to 15.7 MPa) (p>0.05); in terms of bond durability, only the bond strength of the HF1 group presented a statistically significant decrease comparing before and after aging (14.5 to 10.2 MPa). When etched with 3%, 5%, or 10% hydrofluoric acid, the ceramic tested showed stable resin adhesion after long-term aging.

  11. Adsorption behavior of benzenesulfonic acid by novel weakly basic anion exchange resins.

    Science.gov (United States)

    Sun, Yue; Zuo, Peng; Luo, Junfen; Singh, Rajendra Prasad

    2017-04-01

    Two novel weakly basic anion exchange resins (SZ-1 and SZ-2) were prepared via the reaction of macroporous chloromethylated polystyrene-divinylbenzene (Cl-PS-DVB) beads with dicyclohexylamine and piperidine, respectively. The physicochemical structures of the resulting resins were characterized using Fourier Transform Infrared Spectroscopy and pore size distribution analysis. The adsorption behavior of SZ-1 and SZ-2 for benzenesulfonic acid (BA) was evaluated, and the common commercial weakly basic anion exchanger D301 was also employed for comparison purpose. Adsorption isotherms and influence of solution pH, temperature and coexisting competitive inorganic salts (Na 2 SO 4 and NaCl) on adsorption behavior were investigated and the optimum desorption agent was obtained. Adsorption isotherms of BA were found to be well represented by the Langmuir model. Thermodynamic parameters involving ΔH, ΔG and ΔS were also calculated and the results indicate that adsorption is an exothermic and spontaneous process. Enhanced selectivity of BA sorption over sulfate on the two novel resins was observed by comparison with the commercial anion exchanger D301. The fact that the tested resins loaded with BA can be efficiently regenerated by NaCl solution indicates the reversible sorption process. From a mechanistic viewpoint, this observation clearly suggests that electrostatic interaction is the predominant adsorption mechanism. Furthermore, results of column tests show that SZ-1 possesses a better adsorption property than D301, which reinforces the feasibility of SZ-1 for potential industrial application. Copyright © 2016. Published by Elsevier B.V.

  12. HTGR fuel development: loading of uranium on carboxylic acid cation-exchange resins using solvent extraction of nitrate

    International Nuclear Information System (INIS)

    Haas, P.A.

    1975-09-01

    The reference fuel kernel for recycle of 233 U to HTGR's (High-Temperature Gas-Cooled Reactors) is prepared by loading carboxylic acid cation-exchange resins with uranium and carbonizing at controlled conditions. The purified 233 UO 2 (NO 3 ) 2 solution from a fuel reprocessing plant contains excess HNO 3 (NO 3 - /U ratio of approximately 2.2). The reference flowsheet for a 233 U recycle fuel facility at Oak Ridge uses solvent extraction of nitrate by a 0.3 M secondary amine in a hydrocarbon diluent to prepare acid-deficient uranyl nitrate. This nitrate extraction, along with resin loading and amine regeneration steps, was demonstrated in 14 runs. No significant operating difficulties were encountered. The process is controlled via in-line pH measurements for the acid-deficient uranyl nitrate solutions. Information was developed on pH values for uranyl nitrate solution vs NO 3 - /U mole ratios, resin loading kinetics, resin drying requirements, and other resin loading process parameters. Calculations made to estimate the capacities of equipment that is geometrically safe with respect to control of nuclear criticality indicate 100 kg/day or more of uranium for single nitrate extraction lines with one continuous resin loading contactor or four batch loading contactors. (auth)

  13. Fracture Toughness Evaluation of Hybrid and Nano-hybrid Resin Composites after Ageing under Acidic Environment

    Directory of Open Access Journals (Sweden)

    Ferooz M

    2015-03-01

    Full Text Available Statement of Problem: Tooth-coloured restorative materials are brittle with the major shortcomings of sensitivity to flaws and defects. Although various mechanical properties of resin composites have been studied, no fracture toughness test data for nano-hybrid composites under acidic condition for a long period of time has been published. Objectives: To compare the fracture toughness (KIc of two types of resin composites under tensile loading and to assess the effect of distilled water and lactic acid on the resistance of the restoratives to fracture after three months of immersion. Materials and Methods: Four resin composites were used: three nanohybrids [EsteliteSigma Quick (Kuraray, Luna (SDI, Paradigm (3M/ESPE] and one hybrid, Rok (SDI. The specimens were prepared using a custom-made polytetrafluorethylene split mould, stored in distilled water (pH 6.8 or 0.01mol/L lactic acid (pH 4 and conditioned at 37°C for 24 hours, 1 or 3 months. They were loaded under tensile stress using a universal testing machine; the maximum load (N to the specimen failure was recorded and the fracture toughness (KIc was calculated. Data were analysed by ANOVA and Tukey’s test using SPSS, version 18. Results: The results of two-way ANOVA did not show a significant combined effect of material, time, and storage medium on fracture toughness (p= 0.056. However, there was a strong interaction between materials and time (p=0.001 when the storage medium were ignored. After 24 h of immersion in distilled water, Paradigm revealed the highest KIc values followed by Rok, Luna and Estelite. Immersion in either distilled water or lactic acid significantly decreased the fracture toughness of almost all materials as time interval increased. Conclusions: Paradigm showed the highest fracture toughness followed by Rok, Luna and Estelite respectively. As time increased, KIc significantly decreased for almost all resin composites except for Luna which showed a slight decrease

  14. Effect of Polylactic Acid-Degradable Film Mulch on Soil Temperature and Cotton Yield

    Directory of Open Access Journals (Sweden)

    ZHANG Ni

    2016-03-01

    Full Text Available Concern on biodegradable plastic film is increasing because of pollution problems caused by the plastic films currently used. The objective of this field experiment is to evaluate the effect of two thicknesses of polyactic acid-degradable film on soil temperature and cotton yield. The results showed that small holes appeared in the polyactic acid-degradable film at 17~22 d after it was installed. Burst period appeared about 60 d after installation. Splits were observed in the polyactic acid-degradable film at 130 d after installation. Soil temperatures rose slowly under polyactic acid-degradable film during the cotton seedling stage. Daytime soil temperatures were 0.8℃ and 6.2℃ lower under 18μm and 15μm thick polyactic acid-degradable film than non-degradable plastic film(CK, respectively. Nighttime soil temperatures under the polyactic acid-degradable film were about 1℃ warmer than CK. There was no significant difference in cotton yields between the 18μm polyactic acid degradable film treatment and CK. In contrast, yields in the 15μm degradable plastic film treatment were 8.9% less than that in CK. This study indicated that 18μm polyactic acid degradable plastic film had good degradability and no negative effect on cotton growth. The 18μm polyactic acid degradable plastic film can replace ordinary plastic film in agricultural production.

  15. Acid-degradable and bioerodible modified polyhydroxylated materials

    Science.gov (United States)

    Frechet, Jean M. J.; Bachelder, Eric M.; Beaudette, Tristan T.; Broaders, Kyle E.

    2017-05-09

    Compositions and methods of making a modified polyhydroxylated polymer comprising a polyhydroxylated polymer having reversibly modified hydroxyl groups, whereby the hydroxyl groups are modified by an acid-catalyzed reaction between a polydroxylated polymer and a reagent such as acetals, aldehydes, vinyl ethers and ketones such that the modified polyhydroxylated polymers become insoluble in water but freely soluble in common organic solvents allowing for the facile preparation of acid-sensitive materials. Materials made from these polymers can be made to degrade in a pH-dependent manner. Both hydrophobic and hydrophilic cargoes were successfully loaded into particles made from the present polymers using single and double emulsion techniques, respectively. Due to its ease of preparation, processability, pH-sensitivity, and biocompatibility, of the present modified polyhydroxylated polymers should find use in numerous drug delivery applications.

  16. Biocompatibility and bond degradation of poly-acrylic acid coated copper iodide-adhesives.

    Science.gov (United States)

    ALGhanem, Adi; Fernandes, Gabriela; Visser, Michelle; Dziak, Rosemary; Renné, Walter G; Sabatini, Camila

    2017-09-01

    To investigate the effect of poly-acrylic acid (PAA) copper iodide (CuI) adhesives on bond degradation, tensile strength, and biocompatibility. PAA-CuI particles were incorporated into Optibond XTR, Optibond Solo and XP Bond in 0.1 and 0.5mg/ml. Clearfil SE Protect, an MDPB-containing adhesive, was used as control. The adhesives were applied to human dentin, polymerized and restored with composite in 2mm-increments. Resin-dentin beams (0.9±0.1mm 2 ) were evaluated for micro-tensile bond strength after 24h, 6 months and 1year. Hourglass specimens (10×2×1mm) were evaluated for ultimate tensile strength (UTS). Cell metabolic function of human gingival fibroblast cells exposed to adhesive discs (8×1mm) was assessed with MTT assay. Copper release from adhesive discs (5×1mm) was evaluated with UV-vis spectrophotometer after immersion in 0.9% NaCl for 1, 3, 5, 7, 10, 14, 21 and 30 days. SEM, EDX and XRF were conducted for microstructure characterization. XTR and Solo did not show degradation when modified with PAA-CuI regardless of the concentration. The UTS for adhesives containing PAA-CuI remained unaltered relative to the controls. The percent viable cells were reduced for Solo 0.5mg/ml and XP 0.1 or 0.5mg/ml PAA-CuI. XP demonstrated the highest ion release. For all groups, the highest release was observed at days 1 and 14. PAA-CuI particles prevented the bond degradation of XTR and Solo after 1year without an effect on the UTS for any adhesive. Cell viability was affected for some adhesives. A similar pattern of copper release was demonstrated for all adhesives. Copyright © 2017. Published by Elsevier Ltd.

  17. Degradation of ion spent resin using the Fenton's reagent; Degradacao da resina de troca ionica utilizando o reagente de Fenton

    Energy Technology Data Exchange (ETDEWEB)

    Araujo, Leandro Goulart de

    2013-07-01

    The most common method for spent radioactive ion exchange resin treatment is its immobilization in cement, which reduces the radionuclides release into the environment. Although this method is efficient, it increases considerably the final volume of the waste due to the low incorporation capacity. The objective of this work was to develop a degradation method of spent resins arising from the nuclear research reactor located at the Nuclear and Energy Research Institute (IPEN-CNEN/SP), using an Advanced Oxidation Process (AOP) with Fenton's reagents. This method would allow a higher incorporation in cement. Three different resins were evaluated: cationic, anionic and a mixture of both resins. The reactions were conducted varying the catalyst concentration (25, 50, 100 and 150 mM), the volume of hydrogen peroxide (320 to 460 mL), and three different temperatures, 50, 60 and 70 deg C. Degradation of about 98% was achieved using a 50 mM catalyst solution and 330 mL of hydrogen peroxide solution. The most efficient temperature was 60 deg C. (author)

  18. Affinity purification of the voltage-sensitive sodium channel from electroplax with resins selective for sialic acid

    Energy Technology Data Exchange (ETDEWEB)

    James, W.M.; Emerick, M.C.; Agnew, W.S. (Yale Univ. School of medicine, New Haven, CT (USA))

    1989-07-11

    The voltage-sensitive sodium channel present in the eel (Electrophorus electricus) has an unusually high content of sialic acid, including {alpha}-(2{yields}8)-linked polysialic acid, not found in other electroplax membrane glycopeptides. Lectins from Limax flavus (LFA) and wheat germ (WGA) proved the most effective of 11 lectin resins tried. The most selective resin was prepared from IgM antibodies against Neisseria meningitidis {alpha}-(2{yields}8)-polysialic acid which were affinity purified and coupled to Sepharose 4B. The sodium channel was found to bind to WGA, LFA, and IgM resins and was readily eluted with the appropriate soluble carbohydrates. Experiments with LFA and IgM resins demonstrated binding and unbinding rates and displacement kinetics, which suggest highly specific binding at multiple sites on the sodium channel protein. In preparative-scale purification of protein previously fractionated by anion-exchange chromatography, without stabilizing TTX, high yields were reproducibly obtained. Further, when detergent extracts were prepared from electroplax membranes fractionated by low-speed sedimentation, a single step over the IgM resin provided a 70-fold purification, yielding specific activities of 3,200 pmol of ({sup 3}H)TTX-binding sites/mg of protein and a single polypeptide of {approximately}285,000 Da on SDS-acrylamide gels. No small peptides were observed after this 5-h isolation. The authors describe a cation-dependent stabilization with millimolar levels of monovalent and micromolar levels of divalent species.

  19. Influence of ozone and paracetic acid disinfection on adhesion of resilient liners to acrylic resin

    Science.gov (United States)

    2016-01-01

    PURPOSE The aim of this study was to evaluate the effect of paracetic acid (PAA) and ozone disinfection on the tensile bond strength (TBS) of silicone-based resilient liners to acrylic resins. MATERIALS AND METHODS One hundred and twenty dumbbell shaped heat-polymerized acrylic resins were prepared. From the mid segment of the specimens, 3 mm of acrylic were grinded off and separated parts were reattached by resilient liners. The specimens were divided into 2 control (control1, control7) and 4 test groups of PAA and ozone disinfection (PAA1, PAA7, ozone1 and ozone7; n=10). While control groups were immersed in distilled water for 10 min (control1) and 7 days (control7), test groups were subjected to PAA (16 g/L) or ozone rich water (4 mg/L) for 1 cycle (10 min for PAA and 60 min for ozone) per day for 7 days prior to tensile tests. Measurements of the TBS were analyzed using 3-way ANOVA and Tukey's HSD test. RESULTS Adhesive strength of Mollosil decreased significantly by application of ozone disinfection. PAA disinfection had no negative effect on the TBS values of Mollosil and Molloplast B to acrylic resin. Single application of ozone disinfection did not have any negative effect on TBS values of Molloplast B, but prolonged exposure to ozone decreased its adhesive strength. CONCLUSION The adhesion of resilient liners to acrylic was not adversely affected by PAA disinfection. Immersion in ozonated water significantly decreased TBS of Mollosil. Prolonged exposure to ozone negatively affects adhesion of Molloplast B to denture base materials. PMID:27555898

  20. Stability of two resin combinations used as sealants against toothbrush abrasion and acid challenge in vitro.

    Science.gov (United States)

    Yetkiner, Enver; Wegehaupt, Florian Just; Attin, Rengin; Wiegand, Annette; Attin, Thomas

    2014-11-01

    To test the stability of two conventional adhesives when combined with a low-viscosity caries infiltrant used for sealing sound enamel against toothbrush abrasion and acid challenge in vitro. Bovine enamel discs (Ø = 3 mm) randomly assigned to three groups (n = 10/group) were etched with 37% phosphoric acid for 30 s and treated with resins of different monomer contents forming three test groups: (1) Untreated specimens (Control); (2) Infiltrant (Icon, DMG) + conventional enamel bonding adhesive (Heliobond, Ivoclar Vivadent); and (3) Infiltrant + conventional orthodontic adhesive (Transbond XT Primer, 3M Unitek). All specimens were immersed in hydrochloric acid (pH 2.6) for up to 9 days, during which they were exposed to 1825 toothbrush-strokes per day. Calcium dissolution was assessed using Arsenazo III method at 24-h intervals. Data were analyzed by Kruskal-Wallis and Wilcoxon signed ranks tests. Cumulative calcium dissolution for the untreated specimens (39.75 ± 7.32 μmol/ml) exceeded the sealed groups (Icon + Heliobond: 23.44 ± 7.03 μmol/ml; Icon + Transbond XT Primer: 22.17 ± 5.34 μmol/ml). Untreated specimens presented a relatively constant calcium dissolution rate throughout the experimental period, whereas the sealed groups presented a gradual increase indicating weakening of the seal by toothbrush abrasion. Both sealed groups presented significantly lower daily calcium dissolution at all time points compared to the control, except for Group 2 on the last measurement day. Low-viscosity caries infiltrant application on sound enamel prior to conventional resin application provided a protective effect against enamel demineralization, but this effect was not stable when challenged mechanically by toothbrush abrasion.

  1. Ion-exchange Resin Catalyzed Esterification of Lactic Acid with Isopropanol: a Kinetic Study

    Directory of Open Access Journals (Sweden)

    Amrit P. Toor

    2011-05-01

    Full Text Available The kinetic behavior of esterification of lactic acid with isopropanol over an acidic cation exchange resin, Amberlyst 15, was studied under isothermal condition. Isopropyl lactate synthesized in this reaction is an important pharmaceutical intermediate. The experiments were carried out in a stirred batch reactor in the temperature range of 323.15 to 353.15 K. The effect of various parameters such as temperature, molar ratio and catalyst loading was studied. Variation in parameters on rate of reaction demonstrated that the reaction was intrinsically controlled. Kinetic modeling was performed using Eley-Rideal model which acceptably fits the experimental data. The activation energy was found to be 22.007 kJ/mol and frequency factor was 0.036809 l2 g-1 mol-1 min-1 for forward reaction. The value of entropy for the forward reaction was found to be 182.317 J K-1 mol-1 . © 2011 BCREC UNDIP. All rights reserved(Received: 19th January 2011, Revised: 16th March 2011; Accepted: 16th March 2011[How to Cite: A.P. Toor, M. Sharma, S. Thakur, and R. K. Wanchoo. (2011. Ion-exchange Resin Catalyzed Esterification of Lactic Acid with Isopropanol: a Kinetic Study. Bulletin of Chemical Reaction Engineering and Catalysis, 6(1: 39-45. doi:10.9767/bcrec.6.1.791.39-45][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.6.1.791.39-45 || or local:  http://ejournal.undip.ac.id/index.php/bcrec/article/view/791 ] | View in  

  2. Ring cleavage and degradative pathway of cyanuric acid in bacteria.

    Science.gov (United States)

    Cook, A M; Beilstein, P; Grossenbacher, H; Hütter, R

    1985-01-01

    The degradative pathway of cyanuric acid [1,3,5-triazine-2,4,6(1H,3H,5H)-trione] was examined in Pseudomonas sp. strain D. The bacterium grew with cyanuric acid, biuret, urea or NH4+ as sole source of nitrogen, and each substrate was entirely metabolized concomitantly with growth. Enzymes from strain D were separated by chromatography on DEAE-cellulose and three reactions were examined. Cyanuric acid (1 mol) was converted stoichiometrically into 1.0 mol of CO2 and 1.1 mol of biuret, which was conclusively identified. Biuret (1 mol) was converted stoichiometrically into 1.1 mol of NH4+, about 1 mol of CO2 and 1.0 mol of urea, which was conclusively identified. Urea (1 mol) was converted into 1.9 mol of NH4+ and 1.0 mol of CO2. The reactions proceeded under aerobic or anoxic conditions and were presumed to be hydrolytic. Data indicate that the same pathway occurred in another pseudomonad and a strain of Klebsiella pneumoniae. PMID:3904735

  3. Impact of pH and application time of meta-phosphoric acid on resin-enamel and resin-dentin bonding.

    Science.gov (United States)

    Cardenas, A F M; Siqueira, F S F; Bandeca, M C; Costa, S O; Lemos, M V S; Feitora, V P; Reis, A; Loguercio, A D; Gomes, J C

    2018-02-01

    To evaluate the immediate microshear resin-enamel bond strength (μSBS) and the immediate and 6-month microtensile bond strength (μTBS) and nanoleakage (NL) of the adhesive interface performed by different pHs of 40% meta-phosphoric acid (MPA) were compared with conventional 37% ortho-phosphoric acid (OPA) under different application times. Additionally, the enamel etching patterns were evaluated and the chemical/morphological changes induced by these differents groups were evaluated. One hundred and ninety-eight extracted human molars were randomly assigned into experimental groups according to the combination of independent variables: Acid [37% ortho-phosphoric acid (OPA), 40% meta-phosphoric acid (MPA) at pHs of: 0.5, 1 and 2] and Application Time [7, 15 and 30s]. Enamel-bond specimens were prepared and tested under μSBS. Resin-dentin beams were tested under μTBS tested immediately or after 6-months of water storage. Nanoleakage was evaluated using bonded-beams of each tooth/time-period. Enamel etching pattern and chemical and ultra-morphology analyses were also performed. The μSBS (MPa) data were subjected to a two-way repeated measures ANOVA (Acid vs. Application time). For μTBS, Acid vs application time vs storage time data were subjected to three-way ANOVA and Tukey's test (α = 0.05). MPA pH 0.5 showed μTBS similar to OPA, independently of the application time on enamel (p>0.05) or dentin (p>0.05). OPA provided higher nanoleakage values than MPA (p = 0.003). Significant decreases in TBS and increases in NL were only observed for OPA after 6 months (p = 0.001). An increase in the application time resulted in a more pronounced etching pattern for MPA. Chemical analysis showed that dentin demineralized by MPA depicted peaks of brushite and octacalcium phosphate. MPA exposed less collagen than OPA. However, optimal results for MPA were dependent on pH/application time. The use of 40% meta-phosphoric acid with a pH of 0.5 is an alternative acid

  4. Enzymatic oxalic acid regulation correlated with wood degradation in four brown-rot fungi

    Science.gov (United States)

    Anne Christine Steenkjær Hastrup; Frederick Green III; Patricia K. Lebow; Bo Jensen

    2012-01-01

    Oxalic acid is a key component in the initiation of brown-rot decay and it has been suggested that it plays multiple roles during the degradation process. Oxalic acid is accumulated to varying degrees among brown-rot fungi; however, details on active regulation are scarce. The accumulation of oxalic acid was measured in this study from wood degraded by the four brown-...

  5. Process for the preparation of lactic acid and glyceric acid

    Science.gov (United States)

    Jackson, James E [Haslett, MI; Miller, Dennis J [Okemos, MI; Marincean, Simona [Dewitt, MI

    2008-12-02

    Hexose and pentose monosaccharides are degraded to lactic acid and glyceric acid in an aqueous solution in the presence of an excess of a strongly anionic exchange resin, such as AMBERLITE IRN78 and AMBERLITE IRA400. The glyceric acid and lactic acid can be separated from the aqueous solution. Lactic acid and glyceric acid are staple articles of commerce.

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

    Science.gov (United States)

    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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Degradation of chitosan hydrogel dispersed in dilute carboxylic acids by solution plasma and evaluation of anticancer activity of degraded products

    Science.gov (United States)

    Chokradjaroen, Chayanaphat; Rujiravanit, Ratana; Theeramunkong, Sewan; Saito, Nagahiro

    2018-01-01

    Chitosan is a polysaccharide that has been extensively studied in the field of biomedicine, especially its water-soluble degraded products called chitooligosaccharides (COS). In this study, COS were produced by the degradation of chitosan hydrogel dispersed in a dilute solution (i.e., 1.55 mM) of various kinds of carboxylic acids using a non-thermal plasma technology called solution plasma (SP). The degradation rates of chitosan were influenced by the type of carboxylic acids, depending on the interaction between chitosan and each carboxylic acid. After SP treatment, the water-soluble degraded products containing COS could be easily separated from the water-insoluble residue of chitosan hydrogel by centrifugation. The production yields of the COS were mostly higher than 55%. Furthermore, the obtained COS products were evaluated for their inhibitory effect as well as their selectivity against human lung cancer cells (H460) and human lung normal cells (MRC-5).

  8. Kinetics of degradation of ascorbic acid by cyclic voltammetry method

    Directory of Open Access Journals (Sweden)

    Grudić Veselinka V.

    2015-01-01

    Full Text Available Cyclic voltammetry was used to examine the kinetics of degradation of ascorbic acid (AA at different temperatures. It has been shown that the reduction of the concentration of AA in all temperatures follow the kinetics of the first order reaction. The rate constant of the oxidation reaction increases with temperature as follows: 5x10-5; 2x10-4; 1x10-3 and 3x10-3 min-1 at temperatures of 25°C, 35°C, 65°C and 90°C, respectively. The temperature dependence of the rate constant follows Arrhenius equation, and the value of activation energy of the reaction degradation is 48.2 kJ mol-1 . The effect of storage time at a temperature of 90 °C on AA content in fresh juice of green peppers was investigated. It was shown that AA oxidation reaction in the juice is also the first order reaction, while the lower rate constant in relation to the pure AA (5x10-3 min-1 indicates the influence of other substances present in peppers.

  9. SOLVENT EFFECTS IN THE LIQUID-PHASE HYDRATION OF CYCLOHEXENE CATALYZED BY A MACROPOROUS STRONG ACID ION-EXCHANGE RESIN

    NARCIS (Netherlands)

    PANNEMAN, HJ; BEENACKERS, AACM

    1992-01-01

    The liquid-phase hydration of cyclohexene, a pseudo first order reversible reaction catalyzed by a strong acid ion exchange resin, macroporous Amberlite XE 307, was investigated in solvent mixtures of water and sulfolane. A decrease by a factor of 3 and 6 is observed in the experimentally measured

  10. Selective recovery of a pyridine derivative from an aqueous waste stream containing acetic acid and succinonitrile with solvent impregnated resins

    NARCIS (Netherlands)

    Bokhove, J.; Visser, T.J.; Schuur, Boelo; de Haan, A.B.

    2015-01-01

    Solvent impregnated resins (SIRs) were evaluated for the recovery of pyridine derivatives from an aqueous waste-stream containing also acetic acid and succinonitrile. For this purpose, a new solvent was developed, synthesized and impregnated in Amberlite XAD4. Sorption studies were used to determine

  11. Effect of Repeated Acid Challenges on the Color Stability of Resin-Infiltrated Enamel White Spot Lesions

    Science.gov (United States)

    2016-06-01

    seen in patients with xerostomia, poor oral hygiene, cariogenic diet, eating disorders , and orthodontic patients where bonded brackets provide... Effect of Repeated Acid Challenges on the Color Stability of Resin- Infiltrated Enamel White Spot Lesions by Robert A. Lummis...Jr. Lieutenant Commander, Dental Corps United States Public Health Service A thesis submitted to the Faculty of the Comprehensive

  12. Uranium loss from BISO-coated weak-acid-resin HTGR fuel

    International Nuclear Information System (INIS)

    Pearson, R.L.; Lindemer, T.B.

    1977-02-01

    Recycle fuel for the High-Temperature Gas-Cooled Reactor (HTGR) contains a weak-acid-resin (WAR) kernel, which consists of a mixture of UC 2 , UO 2 , and free carbon. At 1900 0 C, BISO-coated WAR UC 2 or UC 2 -UO 2 kernels lose a significant portion of their uranium in several hundred hours. The UC 2 decomposes and uranium diffuses through the pyrolytic coating. The rate of escape of the uranium is dependent on the temperature and the surface area of the UC 2 , but not on a temperature gradient. The apparent activation energy for uranium loss, ΔH, is approximately 90 kcal/mole. Calculations indicate that uranium loss from the kernel would be insignificant under conditions to be expected in an HTGR

  13. Low pressure process for continuous fiber reinforced polyamic acid resin matrix composite laminates

    Science.gov (United States)

    Druyun, Darleen A. (Inventor); Hou, Tan-Hung (Inventor); Kidder, Paul W. (Inventor); Reddy, Rakasi M. (Inventor); Baucom, Robert M. (Inventor)

    1994-01-01

    A low pressure processor was developed for preparing a well-consolidated polyimide composite laminate. Prepreg plies were formed from unidirectional fibers and a polyamic acid resin solution. Molding stops were placed at the sides of a matched metal die mold. The prepreg plies were cut shorter than the length of the mold in the in-plane lateral direction and were stacked between the molding stops to a height which was higher than the molding stops. The plies were then compressed to the height of the stops and heated to allow the volatiles to escape and to start the imidization reaction. After removing the stops from the mold, the heat was increased and 0 - 500 psi was applied to complete the imidization reaction. The heat and pressure were further increased to form a consolidated polyimide composite laminate.

  14. [Screening and functional properties of cholesterol-degrading lactic acid bacteria from Jiangshui].

    Science.gov (United States)

    Li, Xueping; Li, Jianhong; Li, Minquan; Meng, Xiangang

    2015-08-04

    We intended to obtain and characterize lactic acid bacteria with high capacity of cholesterol-degrading. We chose Jiangshui as the experimental material, screened lactic acid bacteria by the culture medium with high cholesterol, and studied other features of lactic acid bacteria like salt-tolerant, acid resistance, then identified the species of lactic acid bacteria by combining physiological and biochemical methods and 16S rDNA sequence. All lactic acid bacteria isolated had the capacity of cholesterol-degrading to some extent. There were 4 strains had high cholesterol-degrading rate (> 75%). Four strains were Lactococcus lactis subsp. lactis, two were Brevibacterium casei, and one was Lactococcus raffinolactis. Cholesterol-degrading lactic acid bacteria were screened from Jiangshui, with application potential for cholesterol degradation.

  15. Selective Adsorption of Ag+ on a New Cyanuric-Thiosemicarbazide Chelating Resin with High Capacity from Acid Solutions

    Directory of Open Access Journals (Sweden)

    Guo Lin

    2017-11-01

    Full Text Available A new cyanuric-thiosemicarbazid (TSC-CC chelating resin was synthesized and employed to selectively adsorb Ag+ from acid solutions. The effects of acid concentration, initial concentration of Ag+, contact time and coexisting ions were investigated. The optimal acid concentration was 0.5 mol/L. The adsorption capacity of Ag+ reached 872.63 mg/g at acid concentration of 0.5 mol/L. The adsorption isotherm was fitted well with the Langmuir isotherm model and the kinetic data preferably followed the pseudo-second order model. The chelating resin showed a good selectivity for the Ag+ adsorption from acid solutions. Fourier transform infrared (FT-IR, X-ray diffraction (XRD, Scanning electron microscopy/energy dispersive spectrometer (SEM-EDS and X-ray photoelectron spectroscopy (XPS were used to study the adsorption mechanism. The chelating and ionic interaction was mainly adsorption mechanism. The adsorbent presents a great potential in selective recovery Ag+ from acid solutions due to the advantage of high adsorption capacity and adapting strongly acidic condition. The recyclability indicated that the (TSC-CC resin had a good stability and can be recycled as a promising agent for removal of Ag+.

  16. Improvement of epoxy resin properties by incorporation of TiO2 nanoparticles surface modified with gallic acid esters

    International Nuclear Information System (INIS)

    Radoman, Tijana S.; Džunuzović, Jasna V.; Jeremić, Katarina B.; Grgur, Branimir N.; Miličević, Dejan S.; Popović, Ivanka G.; Džunuzović, Enis S.

    2014-01-01

    Highlights: • Nanocomposites of epoxy resin and TiO 2 nanoparticles surface modified with gallates. • The T g of epoxy resin was increased by incorporation of surface modified TiO 2 . • WVTR of epoxy resin decreased in the presence of surface modified TiO 2 nanoparticles. • WVTR of nanocomposites was reduced with increasing gallates hydrophobic chain length. • Modified TiO 2 nanoparticles react as oxygen scavengers, inhibiting steel corrosion. - Abstract: Epoxy resin/titanium dioxide (epoxy/TiO 2 ) nanocomposites were obtained by incorporation of TiO 2 nanoparticles surface modified with gallic acid esters in epoxy resin. TiO 2 nanoparticles were obtained by acid catalyzed hydrolysis of titanium isopropoxide and their structural characterization was performed by X-ray diffraction and transmission electron microscopy. Three gallic acid esters, having different hydrophobic part, were used for surface modification of the synthesized TiO 2 nanoparticles: propyl, hexyl and lauryl gallate. The gallate chemisorption onto surface of TiO 2 nanoparticles was confirmed by Fourier transform infrared and ultraviolet–visible spectroscopy, while the amount of surface-bonded gallates was determined using thermogravimetric analysis. The influence of the surface modified TiO 2 nanoparticles, as well as the length of hydrophobic part of the gallate used for surface modification of TiO 2 nanoparticles, on glass transition temperature, barrier, dielectric and anticorrosive properties of epoxy resin was investigated by differential scanning calorimetry, water vapor transmission test, dielectric spectroscopy, electrochemical impedance spectroscopy and polarization measurements. Incorporation of surface modified TiO 2 nanoparticles in epoxy resin caused increase of glass transition temperature and decrease of the water vapor permeability of epoxy resin. The water vapor transmission rate of epoxy/TiO 2 nanocomposites was reduced with increasing hydrophobic part chain length of

  17. Influence of hydrofluoric acid on extraction of thorium using a commercially available extraction chromatographic resin.

    Science.gov (United States)

    Shimada-Fujiwara, Asako; Hoshi, Akiko; Kameo, Yutaka; Nakashima, Mikio

    2009-05-01

    The dependence of Th recovery on hydrofluoric acid (HF) concentration in nitric acid (HNO(3)) solutions (1-5 mol/dm(3)) containing 1x10(-6) mol/dm(3) of Th and various concentrations of HF and the elution behavior were studied using a commercially available UTEVA (for uranium and tetravalent actinide) resin column. Thorium recovery decreased with an increase in HF concentration in the sample solutions. The concentration of HF at which Th recovery started to decrease was approximately 1x10(-4) mol/dm(3) in 1 mol/dm(3) HNO(3) solution, approximately 1x10(-3) mol/dm(3) in 3 mol/dm(3) HNO(3) solution, and approximately 1x10(-2) mol/dm(3) in 5 mol/dm(3) HNO(3) solution. When Al(NO(3))(3) (0.2 mol/dm(3)) or Fe(NO(3))(3) (0.6 mol/dm(3)) was added as a masking agent for F(-) to the Th solution containing 1x10(-1) mol/dm(3) HF and 1 mol/dm(3) HNO(3), Th recovery improved from 1.4+/-0.3% to 95+/-5% or 93+/-3%. Effective extraction of Th using UTEVA resin was achieved by selecting the concentration of HNO(3) and/or adding masking agents such as Al(NO(3))(3) according to the concentration of HF in the sample solution.

  18. Releasing Pattern of Applied Phosphorus and Distribution Change of Phosphorus Fractions in the Acid Upland Soils with Successive Resin Extraction

    Directory of Open Access Journals (Sweden)

    Arief Hartono

    2008-05-01

    Full Text Available The releasing pattern of applied P in the acid upland soils and the soil properties influencing the pattern were studied. Surface horizons of six acid upland soils from Sumatra, Java and Kalimantan were used in this study. The releasing pattern of applied P (300 mg P kg-1 of these soils were studied by successive resin extraction. P fractionation was conducted to evaluate which fractions released P to the soil solution after successive resin extraction. The cumulative of resin-Pinorganic (Pi release of soils was fitted to the first order kinetic. Regression analyses using factor scores obtained from the previous principal components analyses was applied to determine soil properties influencing P releasing pattern. The results suggested that the maximum P release was significantly (P < 0.05 increased by acidity plus 1.4 nm mineral-related factor (PC2 i.e. exchangeable Al and 1.4 nm minerals (smectite and vermiculite and decreased by oxide related factor (PC1 i.e. aluminum (Al plus 1/2 iron (Fe (by ammonium oxalate, crystalline Al and Fe oxides, cation exchange capacity, and clay content. P fractionation analysis after successive resin extraction showed that both labile and less labile in the form of NaHCO3-Pi and NaOH-Pi fractions, respectively, can be transformed into resin-Pi when in the most labile resin-Pi is depleted. Most of P released in high oxides soils were from NaOH-Pi fraction while in low oxides soils were from NaHCO3-Pi. P release from the former fraction resulted in the maximum P release lower than that of the latter one. When NaHCO3-Pi was high, NaOH-Pi was relatively more stable than NaHCO3-Pi despite resin-Pi removal. NaHCO3-Pi and NaOH-Pi are very important P fractions in replenishing resin-Pi in these acid upland soils.

  19. Effect of scrubbing operating conditions on adipic acid degradation. Final report February-August 1980

    Energy Technology Data Exchange (ETDEWEB)

    Chang, J.C.S.

    1981-02-01

    The report gives results of adipic acid degradation tests at EPA's IERL-RTP limestone SO2 scrubber, to investigate the effects of operating variables on unaccountable adipic acid loss. It was found that: (1) adipic acid degradation could not be totally quenched by only lowering the pH below 5.0; (2) pH change did significantly affect unaccountable adipic acid loss (other factors may increase the adipic acid degradation rate at both high and low pH); (3) an appreciable amount of adipic acid loss was caused by coprecipitation with calcium sulfite; and (4) forced oxidation could aggravate the adipic acid degradation loss even at pH below 5.0. Adipic acid loss could be reduced: at high sulfite concentrations (the adipic acid degradation rate could be decreased by lowering the destructive free radical concentrations by high total sulfite); in the presence of manganous ion at low pH (the metal ion might act as an inhibitor to the oxidative degradation reaction at low pH); and with high natural oxidation (the adipic acid coprecipitation loss might be reduced with the high natural oxidation). Adipic acid degradation (loss) data were compared from four different test facilities. Most of the data also support these conclusions.

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

    Science.gov (United States)

    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.

  1. Biogenic glutamic acid-based resin: Its synthesis and application in the removal of cobalt(II).

    Science.gov (United States)

    Jamiu, Zakariyah A; Saleh, Tawfik A; Ali, Shaikh A

    2017-04-05

    Inexpensive biogenic glutamic acid has been utilized to synthesize a cross-linked dianionic polyelectrolyte (CDAP) containing metal chelating ligands. Cycloterpolymerization, using azoisobutyronitrile as an initiator, of N,N-diallylglutamic acid hydrochloride, sulfur dioxide and a cross-linker afforded a pH-responsive cross-linked polyzwitterionic acid (CPZA) which upon basification with NaOH was converted into CDAP. The new resin, characterized by a multitude of spectroscopic techniques as well as Scanning Electron Microscopy (SEM) and Brunauer-Emmett-Teller (BET) analyses, was evaluated for the removal of Co(II) as a model case under different conditions. The adsorption capacity of 137mgg -1 does indeed make the resin as one of the most effective sorbents in recent times. The resin leverages its cheap natural source and ease of regeneration in combination with its high and fast uptake capacities to offer a great promise for wastewater treatment. The resin has demonstrated remarkable efficiency in removing toxic metal ions including arsenic from a wastewater sample. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Effect of Eu(III) on the degradation of malic acid by Pseudomonas fluorescens

    International Nuclear Information System (INIS)

    Nankawa, T.; Ozaki, T.; Ohnuki, T.; Suzuki, Y.; Francis, A.J.

    2005-01-01

    Full text of publication follows: The transuranic elements, such as Am(III) and Cm(III), are highly toxic because they emit high-energy α particles and have long half-lives. To estimate their long-term environmental behavior, we need to elucidate degradation of actinide-organic complexes by microorganisms. We studied the biodegradation of Eu(III)-malic acid complexes by Pseudomonas fluorescens. Malic acid is ubiquitous in the environment and is one of the microbial metabolites that is part of the tri-carboxylic acid (TCA) cycle. Europium(III) is a good analogue for Am(III) and Cm(III). To investigate the effect of Eu(III) on the degradation of malic acid by P. fluorescens, we compared the degradation behavior of Eu(III)-malic acid complexes to that of Fe(III) and Al(III)-malic acid complexes. In the medium containing 1 mM malic acid and 0-0.5 mM Fe(III), malic acid was degraded completely. In the medium containing 1 mM malic acid and 0.05-0.5 mM Al(III), malic acid was degraded until the concentration of malic acid became equal to that of Al(III), indicating that Al(III)-malic acid complex with 1: 1 molar ratio was recalcitrant to biodegradation. In the medium containing 1 mM malic acid and 0.05-0.5 mM Eu(III), degradation of malic acid was not observed. The effect of metals on degradation of malic acid was in the order of Fe(III) < Al(III) < Eu(III). The stability constants of 1:1 Fe(III)-, Al(III)-, and Eu(III)-malic acid complexes are 7.1, 4.6, and 4.9, respectively. These results indicate that degradability of malic acid does not depend on the stability constants of metal-malic acid complexes. We found that 10 mM malic acid was degraded in the presence of 0.05 and 0.1 mM Eu(III) but 1 mM malic acid was not degraded in the presence of 0.05 and 0.1 mM Eu(III). The degradation rate of malic acid increased with a decreasing ratio of Eu(III) to malic acid. (authors)

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

    DEFF Research Database (Denmark)

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

    1992-01-01

    The formation of four major degradation products of 5-aminosalicylic acid (5-ASA) in buffered solutions at pH 7.0 was demonstrated by gradient HPLC analysis. The isolation and structural elucidation of the resulting degradation products showed that the degradation of 5-ASA led to the formation...

  4. Fabrication of micro-dot arrays and micro-walls of acrylic acid/melamine resin on aluminum by AFM probe processing and electrophoretic coating

    Energy Technology Data Exchange (ETDEWEB)

    Kurokawa, S.; Kikuchi, T.; Sakairi, M. [Graduate School of Engineering, Hokkaido University, N-13, W-8, Kita-Ku, Sapporo 060-8628 (Japan); Takahashi, H. [Graduate School of Engineering, Hokkaido University, N-13, W-8, Kita-Ku, Sapporo 060-8628 (Japan)], E-mail: takahasi@elechem1-mc.eng.hokudai.ac.jp

    2008-11-30

    Micro-dot arrays and micro-walls of acrylic acid/melamine resin were fabricated on aluminum by anodizing, atomic force microscope (AFM) probe processing, and electrophoretic deposition. Barrier type anodic oxide films of 15 nm thickness were formed on aluminum and then the specimen was scratched with an AFM probe in a solution containing acrylic acid/melamine resin nano-particles to remove the anodic oxide film locally. After scratching, the specimen was anodically polarized to deposit acrylic acid/melamine resin electrophoretically at the film-removed area. The resin deposited on the specimen was finally cured by heating. It was found that scratching with the AFM probe on open circuit leads to the contamination of the probe with resin, due to positive shifts in the potential during scratching. Scratching of the specimen under potentiostatic conditions at -1.0 V, however, resulted in successful resin deposition at the film-removed area without probe contamination. The rate of resin deposition increased as the specimen potential becomes more positive during electrophoretic deposition. Arrays of resin dots with a few to several tens {mu}m diameter and 100-1000 nm height, and resin walls with 100-1000 nm height and 1 {mu}m width were obtained on specimens by successive anodizing, probe processing, and electrophoretic deposition.

  5. Characterization of hydroxybenzoic acid chelating resins: equilibrium, kinetics, and isotherm profiles for Cd(II and Pb(II uptake

    Directory of Open Access Journals (Sweden)

    BHAVNA A. SHAH

    2011-06-01

    Full Text Available Chelating ion-exchange resins were synthesized by polycondensation of ortho/para hydroxybenzoic acid with resorcinol/catechol employing formaldehyde as cross-linking agent at 80±5 °C in DMF. The resins were characterized by FTIR and XRD. The uptake behaviour of synthesized resins for Cd(II and Pb(II ions have been studied depending on contact time, pH, metal ion concentration and temperature. The sorption data obtained at optimized conditions were analyzed by the Langmuir and Freundlich isotherms. Experimental data of all metal–resin system were best represented by the Freundlich isotherm. The maximum obtained sorption capacity for cadmium was 69.53 mg g-1 and 169.32 mg g-1 for Lead. The adsorption process follows first order kinetics and the specific rate constant Kr was obtained by the application of the Lagergan equation. Thermodynamic parameters ∆Gads, ∆Sads and ∆Hads were calculated for the metal–resin systems. The external diffusion rate constant (KS and the intra-particle diffusion rate constant (Kid were calculated by the Spahn–Schlunder and Weber–Morris models, respectively. The sorption process was found to follow an intra-particle diffusion phenomenon.

  6. Biologically Safe Poly(l-lactic acid) Blends with Tunable Degradation Rate: Microstructure, Degradation Mechanism, and Mechanical Properties.

    Science.gov (United States)

    Oyama, Hideko T; Tanishima, Daisuke; Ogawa, Ryohei

    2017-04-10

    Although poly(l-lactic acid) (PLLA) is reputed to be biodegradable in the human body, its hydrophobic nature lets it persist for ca. 5.5 years. This study demonstrates that biologically safe lactide copolymers, poly(aspartic acid-co-l-lactide) (PAL) and poly(malic acid-co-l-lactide) (PML), dispersed in the PLLA function as detonators (triggers) for its hydrolytic degradation under physiological conditions. The copolymers significantly enhance hydrolysis, and consequently, the degradation rate of PLLA becomes easily tunable by controlling the amounts of PAL and PML. The present study elucidates the effects of uniaxial drawing on the structural development, mechanical properties, and hydrolytic degradation under physiological conditions of PLLA blend films. At initial degradation stages, the mass loss was not affected by uniaxial drawing; however, at late degradation stages, less developed crystals as well as amorphous chains were degradable at low draw ratio (DR), whereas not only highly developed crystals but also the oriented amorphous chains became insensitive to hydrolysis at high DR. Our work provides important molecular level results that demonstrate that biodegradable materials can have superb mechanical properties and also disappear in a required time under physiological conditions.

  7. Isolation and characterization of isopimaric acid-degrading bacteria from a sequencing batch reactor.

    OpenAIRE

    Wilson, A E; Moore, E R; Mohn, W W

    1996-01-01

    We isolated two aerobic, gram-negative bacteria which grew on the diterpene resin acid isopimaric acid (IpA) as the sole carbon source and electron donor. The source of the isolates was a sequencing batch reactor treating a high-strength process stream from a paper mill. The isolates, IpA-1 and IpA-2, also grew on pimaric and dehydroabietic acids, and IpA-1 grew on abietic acid. Both strains used fatty acids, but neither strain used camphor, sitosterol, or betulin. Strain IpA-1 grew anaerobic...

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

    Science.gov (United States)

    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. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  9. Separation of Technetium in Nitric Acid Solution With an Extractant Impregnated Resin

    International Nuclear Information System (INIS)

    Jei Kwon Moon; Eil Hee Lee; Chong-Hun Jung; Byung Chul Lee

    2006-01-01

    An extractant impregnated resin (EIR) was prepared by impregnation of Aliquat 336 into Amberlite XAD-4 for separation of technetium from rhodium in nitric acid solution. The prepared EIR showed high preference for rhenium (chemical analogue of technetium) over rhodium. The adsorption isotherms for rhenium were described well by Langmuir equation in both the single and multi-component systems. Maximum adsorption capacities obtained by modelling the isotherms of rhenium were 2.01 meq g -1 and 1.97 meq g -1 for the single and the multi-component systems, respectively. Column tests were also performed to confirm the separation efficiency of rhenium using a jacketed glass column (diam. 11 x L 150). The EIR column showed successful separation of rhenium with the breakthrough volume of about 122 BV for the breakthrough concentration of 0.08. Also the breakthrough data were modelled successfully by assuming a homogeneous diffusion model in the particle phase. The diffusivities obtained from the modelling were in the order of 10 -7 cm 2 min -1 for a rhenium. The rhenium adsorbed on the bed could be eluted with a high purity by using a nitric acid solution. (authors)

  10. Abietic acid isolated from pine resin (Resina Pini) enhances angiogenesis in HUVECs and accelerates cutaneous wound healing in mice.

    Science.gov (United States)

    Park, Jun Yeon; Lee, Yun Kyung; Lee, Dong-Soo; Yoo, Jeong-Eun; Shin, Myoung-Sook; Yamabe, Noriko; Kim, Su-Nam; Lee, Seulah; Kim, Ki Hyun; Lee, Hae-Jeung; Roh, Seok Sun; Kang, Ki Sung

    2017-05-05

    Resin known as Resina Pini is listed in the Korean and Japanese pharmacopoeias and has been used for treating skin wounds and inflammation. Resin is composed of more than 50% abietic acid and 10% neutral substances. In the present study, the wound-healing effects of abietic acid and the possible underlying mechanism of action were investigated in various in vitro and in vivo models. The effects of abietic acid on tube formation and migration were measured in human umbilical vein vascular endothelial cells (HUVECs). Protein expression of mitogen-activated protein kinase (MAPK) activation was evaluated via Western blotting analysis. The wound-healing effects of abietic acid were assessed using a mouse model of cutaneous wounds. The results showed that abietic acid enhanced cell migration and tube formation in HUVECs. Abietic acid induced significant angiogenic potential, which is associated with upregulation of extracellular signal-regulated kinase (ERK) and p38 expression. Additionally, 0.8μM abietic acid-treated groups showed accelerated wound closure compared to the controls in a mouse model of cutaneous wounds. The current data indicate that abietic acid treatment elevated cell migration and tube formation in HUVECs by the activation of ERK and p38 MAPKs. We suggest that abietic acid can be developed as a wound-healing agent. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    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.

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

    DEFF Research Database (Denmark)

    Meyhoff, Ulrich; Riber, Ulla; Boas, Ulrik

    2015-01-01

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

  13. Surface Engineering of PAMAM-SDB Chelating Resin with Diglycolamic Acid (DGA) Functional Group for Efficient Sorption of U(VI) and Th(IV) from Aqueous Medium

    Energy Technology Data Exchange (ETDEWEB)

    Ilaiyaraja, P.; Venkatraman, B., E-mail: chemila07@gmail.com [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam (India); Deb, A.K. Singha [Chemical Engineering Division, Bhabha Atomic Research Centre, Mumbai (India); Ponraju, D. [Safety Engineering Division, Indira Gandhi Centre for Atomic Research, Kalpakkam (India); Ali, Sk. Musharaf [Chemical Engineering Division, Bhabha Atomic Research Centre, Mumbai (India)

    2017-04-15

    Highlights: • A new DGA-PAMAM-SDB chelating resin has been synthesized for actinide sorption. • Maximum sorption capacities of resin are 682 and 544.2 mg g{sup −1}for U(VI) and Th(IV). • DGA-PAMAM-SDB chelating resin could be regenerated and reused. • DFT calculation of actinides interaction with resin corroborates the experimental. • Resin is effective for sorption of actinides from both aqueous and HNO{sub 3} medium. - Abstract: A novel chelating resin obtained via growth of PAMAM dendron on surface of styrene divinyl benzene resin beads, followed by diglycolamic acid functionalization of the dendrimer terminal. Batch experiments were conducted to study the effects of pH, nitric acid concentration, amount of adsorbent, shaking time, initial metal ion concentration and temperature on U(VI) and Th(IV) adsorption efficiency. Diglycolamic acid terminated PAMAM dendrimer functionalized styrene divinylbenzene chelating resin (DGA-PAMAM-SDB) is found to be an efficient candidate for the removal of U(VI) and Th(IV) ions from aqueous (pH > 4) and nitric acid media (> 3 M). The sorption equilibrium could be reached within 60 min, and the experimental data fits with pseudo-second-order model. Langmuir sorption isotherm model correlates well with sorption equilibrium data. The maximum U(VI) and Th(IV) sorption capacity onto DGA-PAMAMG{sub 5}-SDB was estimated to be about 682 and 544.2 mg g{sup −1} respectively at 25 °C. The interaction of actinides and chelating resin is reversible and hence, the resin can be regenerated and reused. DFT calculation on the interaction of U(VI) and Th(IV) ions with chelating resin validates the experimental findings.

  14. Thermal degradation kinetics of polylactic acid/acid fabricated cellulose nanocrystal based bionanocomposites.

    Science.gov (United States)

    Monika; Dhar, Prodyut; Katiyar, Vimal

    2017-11-01

    Cellulose nanocrystals (CNC) are fabricated from filter paper (as cellulosic source) by acid hydrolysis using different acids such as sulphuric (H 2 SO 4 ), phosphoric (H 3 PO 4 ), hydrochloric (HCl) and nitric (HNO 3 ) acid. The resulting acid derived CNC are melt mixed with Polylactic acid (PLA) using extruder at 180°C. Thermogravimetric (TGA) result shows that increase in 10% and 50% weight loss (T 10 , T 50 ) temperature for PLA-CNC film fabricated with HNO 3 , H 3 PO 4 and HCl derived CNC have improved thermal stability in comparison to H 2 SO 4 -CNC. Nonisothermal kinetic studies are carried out with modified-Coats-Redfern (C-R), Ozawa-Flynn-Wall (OFW) and Kissinger method to predict the kinetic and thermodynamic parameters. Subsequently prediction of these parameter leads to the proposal of thermal induced degradation mechanism of nanocomposites using Criado method. The distribution of E a calculated from OFW model are (PLA-H 3 PO 4 -CNC: 125-139 kJmol -1 ), (PLA-HNO 3 -CNC: 126-145 kJmol -1 ), (PLA-H 2 SO 4 -CNC: 102-123 kJmol -1 ) and (PLA-HCl-CNC: 140-182 kJmol -1 ). This difference among E a for the decomposition of PLA-CNC bionanocomposite is probably due to various acids used in this study. The E a calculated by these two methods are found in consonance with that observed from Kissinger method. Further, hyphenated TG-Fourier transform infrared spectroscopy (FTIR) result shows that gaseous products such as CO 2 , CO, lactide, aldehydes and other compounds are given off during the thermal degradation of PLA-CNC nanocomposite. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Reduction of polyester resin shrinkage by means of epoxy resin

    International Nuclear Information System (INIS)

    Pietrzak, M.; Brzostowski, A.

    1981-01-01

    An attempt was made to decrease the shrinkage of unsaturated polyester resin, taking place during radiation-induced curing, by the addition of epoxy resin. In order to combine chemically both resins, the epoxy component was modified with cinnamic and acrylic acids. A composition of 90 parts of polyester resin, 10 parts of epoxy resin modified with cinnamic acid, and 150 parts of a silica filler showed a volume shrinkage of 1.2%. (author)

  16. Distribution of 14 elements from two solutions simulating Hanford HLW Tank 102-SY (acid-dissolved sludge and acidified supernate) on four cation exchange resins and five anion exchange resins having different functional groups

    International Nuclear Information System (INIS)

    Marsh, S.F.; Svitra, Z.V.; Bowen, S.M.

    1995-01-01

    As part of the Tank Waste Remediation System program at Los Alamos, we evaluated a series of cation exchange and anion exchange resins for their ability to remove hazardous components from radioactive high-level waste (HLW). The anion exchangers were Reillex TM HPQ, a polyvinyl pyridine resin, and four strong-base polystyrene resins having trimethyl, tri ethyl, tri propyl, and tributyl amine as their respective functional groups. The cation exchange resins included Amberlyst TM 15 and Amberlyst tM XN-1010 with sulfonic acid functionality, Duolite TM C-467 with phosphonic acid functionality, and poly functional Diphonix TM with di phosphonic acid, sulfonic acid, and carboxylic acid functionalities. We measured the distributions of 14 elements on these resins from solutions simulating acid-dissolved sludge (pH 0.6) and acidified supernate (pH 3.5) from underground storage tank 102-SY at the Hanford Reservation near Richland, Washington, USA. To these simulants, we added the appropriate radionuclides and used gamma spectrometry to measure fission products (Ce, Cs, Sr, Tc, and Y), actinides (U, Pu, and Am), and matrix elements (Cr, Co, Fe, Mn, Zn, and Zr). For each of the 252 element/resin/solution combinations, distribution coefficients (Kds) were measured for dynamic contact periods of 30 minutes, 2 hours, and 6 hours to obtain information about sorption kinetics from these complex media. Because we measured the sorption of many different elements, the tabulated results indicate which unwanted elements are most likely to interfere with the sorption of elements of special interest. On the basis of these 756 measured Kd values, we conclude that some of the tested resins appear suitable for partitioning hazardous components from Hanford HLW. (author). 10 refs., 11 tabs

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

    International Nuclear Information System (INIS)

    Nageswara Rao, A.; Sivasankar, B.; Sadasivam, V.

    2009-01-01

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

  18. SEPARATION AND PRECONCENTRATION OF COPPER (II ION BY FATTY HYDROXAMIC ACIDS IMMOBILIZED ONTO AMBERLITE XAD – 4 RESIN

    Directory of Open Access Journals (Sweden)

    Dedy Suhendra

    2010-06-01

    Full Text Available A method of copper (II ion preconcentration and separation from other ions by using a column containing fatty hydroxamic acids - loaded Amberlite XAD 4 resin (FHA-Amb is described. Several factors, which affect the separation and preconcentration efficiency such as pH, sample volume, and concentration of eluent and flow rate, have been investigated.  A quantitative recovery of copper (II ion from FHA-Amb resin column was obtained using 10% HNO3 solutions as eluent with a preconcentration factor of 60. A method for separation of Cu(II from Zn(II and Cd(II is proposed.  A rapid sample throughput, a clean separation, a high preconcentration factor and simplicity are the main advantages in these analytical procedures.   Keywords: extraction, preconcentration, fatty hydroxamic acid, copper (ii ion, amberlite XAD-4

  19. Efficient in situ separation and production of L-lactic acid by Bacillus coagulans using weak basic anion-exchange resin.

    Science.gov (United States)

    Zhang, Yitong; Qian, Zijun; Liu, Peng; Liu, Lei; Zheng, Zhaojuan; Ouyang, Jia

    2018-02-01

    To get rid of the dependence on lactic acid neutralizer, a simple and economical approach for efficient in situ separation and production of L-lactic acid was established by Bacillus coagulans using weak basic anion-exchange resin. During ten tested resins, the 335 weak basic anion-exchange resins demonstrated the highest adsorption capacity and selectivity for lactic acid recovery. The adsorption study of the 335 resins for lactic acid confirmed that it is an efficient adsorbent under fermentation condition. Langmuir models gave a good fit to the equilibrium data at 50 °C and the maximum adsorption capacity for lactic acid by 335 resins was about 402 mg/g. Adsorption kinetic experiments showed that pseudo-second-order kinetics model gave a good fit to the adsorption rate. When it was used for in situ fermentation, the yield of L-lactic acid by B. coagulans CC17 was close to traditional fermentation and still maintained at about 82% even after reuse by ten times. These results indicated that in situ separation and production of L-lactic acid using the 335 resins were efficient and feasible. This process could greatly reduce the dosage of neutralizing agent and potentially be used in industry.

  20. Gas chromatographic determination of organic acids from fruit juices by combined resin mediated methylation and extraction in supercritical carbon dioxide.

    Science.gov (United States)

    Barden, T J; Croft, M Y; Murby, E J; Wells, R J

    1997-10-17

    A procedure in which anionic analytes, trapped on ion exchange resin, are simultaneously methylated and released using methyl iodide in either supercritical carbon dioxide or acetonitrile has been extended to polyfunctional organic acids. The combined SFE methylation of fruit juice acids trapped onto ion exchange resin proceeds in good yield producing the methyl esters of fumaric, succinic, malic, tartaric, isocitric and citric acids which are readily separated by GC. Using this procedure low concentrations of one acid can be detected and quantitated in the presence of very high concentrations of another. This new method detects tartaric acid at levels of 10 ppm in juices containing 10,000 ppm citric acid. Quantitation was performed either by using GC-FID with triethyl citrate or diethyl tartrate as internal standards or with the element specific calibration capability of the GC-AED. A simple new technique for the determination of citric/isocitric acid ratio is now available. Also, in contrast to HPLC methods, the identity of an analyte is readily confirmed by GC-MS.

  1. [Effect of hydrofluoric acid concentration on the surface morphology and bonding effectiveness of lithium disilicate glass ceramics to resin composites].

    Science.gov (United States)

    Hailan, Qian; Lingyan, Ren; Rongrong, Nie; Xiangfeng, Meng

    2017-12-01

    This study aimed at determining the influence of hydrofluoric acid (HF) in varied concentrations on the surface morphology of lithium disilicate glass ceramics and bond durability between resin composites and post-treated lithium disilicate glass ceramics. After being sintered, ground, and washed, 72 as-prepared specimens of lithium disilicate glass ceramics with dimensions of 11 mm×13 mm×2 mm were randomly divided into three groups. Each group was treated with acid solution [32% phosphoric acid (PA) or 4% or 9.5% HF] for 20 s. Then, four acidified specimens from each group were randomly selected. One of the specimens was used to observe the surface morphology using scanning electron microscopy, and the others were used to observe the surface roughness using a surface roughness meter (including Ra, Rz, and Rmax). After treatment with different acid solutions in each group, 20 samples were further treated with silane coupling agent/resin adhesive/resin cement (Monobond S/Multilink Primer A&B/Multilink N), followed by bonding to a composite resin column (Filtek™ Z350) with a diameter of 3 mm. A total of 20 specimens in each group were randomly divided into two subgroups, which were used for measuring the microshear bond strength, with one of them subjected to cool-thermal cycle for 20 000 times. The surface roughness (Ra, Rz, and Rmax) of lithium disilicate glass ceramics treated with 4% or 9.5% HF was significantly higher than that of the ceramic treated with PA (Pglass ceramics treated with 9.5% HF also demonstrated better surface roughness (Rz and Rmax) than that of the ceramics treated with 4% HF. Cool-thermal cycle treatment reduced the bond strength of lithium disilicate glass ceramics in all groups (Pglass ceramics treated with HF had higher bond strength than that of the ceramics treated with PA. The lithium disilicate glass ceramics treated with 4% HF had higher bond strength than that of the ceramics treated with 9.5% HF (Pglass ceramics treated with 4

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

    Science.gov (United States)

    Frechet, Jean M. J. [Oakland, CA; Standley, Stephany M [Evanston, IL; Jain, Rachna [Milpitas, CA; Lee, Cameron C [Cambridge, MA

    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.

  3. Adsorption characteristics of 14C-labeled alanine, aspartic acid and adenosine triphosphate by metal-chelating resins

    International Nuclear Information System (INIS)

    Ishiyama, Toshio; Matsunami, Tadao; Shibata, Setsuko; Honda, Yoshihide.

    1987-01-01

    (1) Adsorption properties of 14 C-alanine, 14 C-ATP (adenosine triphosphate) and 14 C-aspartic acid on the metal-chelating resins were determined and found that the Cu(II)-Chelex 100 and Fe(III)-Unicellex UR10, Fe(III)-Chelex 100 chelating resins were highly effective for the adsorption of 14 C-alanine and 14 C-ATP, respectively. (2) Desorption rate of 14 C-ATP from the Fe(III)-Unicellex UR10 and Fe(III)-Chelex 100 resins was somewhat higher than the case of 14 C-alanine, probably because the coordination bonds of Cu-alanine might be stronger than those of Fe-ATP. Thus, 14 C-labeled organic compounds such as 14 C-alanine and 14 C-ATP of a low activity concentration (3.7 mBq/ml) (1 x 10 -7 μCi/ml) in aqueous solution may be measured with liquid scintillation counter after pre-concentration by use of the Fe(III)- and Cu(II)-chelating resin columns. (author)

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

    International Nuclear Information System (INIS)

    Benakli, A.; Chomat, L.; Le Bescop, P.; Wall, J.

    2015-01-01

    In the framework of Spent Fuel Pools (SFP) lifetime studies, an investigation of the Portland cement degradation in boric acid has been requested by the Electric Power Research Institute. The main goal of this study is to identify the physico-chemical degradation mechanisms involved in boric acid media. Both experimental and modeling approaches are considered. Concerning degradation experiments, sample of cement paste are immersed during three and nine months in a boric acid solution at 2400 ppm that is periodically renewed. Boric acid concentration has been chosen to be representative of SFP solution. Results will be confronted with reactive transport numerical calculations performed by the reactive transport code HYTEC associated with a dedicated extended database called Thermoddem. The analysis of degradation solution revealed a main ions release mechanism driven by diffusion especially for calcium, nitrate, sodium and sulfate. Leaching behavior of magnesium seems to be more complex. Decalcification is the major degradation process involved, even if a non-negligible contribution of further cations (Mg 2+ , Na + ) and anions (SO 4 2- ) has been noticed. Analysis of degradation soution also revealed that kinetic of Portland cement paste degradation in boric acid is higher than in pure water, regarding the degraded depths measured and calcium leaching rate. This observation has been confirmed by solid characterization. Microstructure analysis of degraded Portland cement paste showed a global porosity increase in the degraded zone that might be mainly attributed to Portlandite dissolution. An Ettringite reprecipitation in the degraded zone has been suspected but could also be Ettringite-like phases containing boron. The analysis techniques used did not allow us to differentiate it, and no others specific mineral phases containing boron has been identified. Profile pattern by XRD analysis allowed us to identify four zones composing the degraded Portland cement paste

  5. Influence of water solubility, side chain degradability and side chain configuration on the degradation of phthalic acid esters under methanogenic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Alnervik, M.

    1996-12-31

    Water solubility and degradability of side chains estrifying phthalic acid are factors possible to influence the degradation of phthalic acid esters (PAEs). To investigate the importance of these factors degradation of butyl 2-ethylhexyl phthalate (BEHP), bis(2-ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP), dihexyl phthalate (DHP), dioctyl phthalate (DOP) and didecyl phthalate (DDP) were examined under methanogenic conditions as well as was the degradability of the alcohols estrifying these PAEs. We also investigated if the degradation of resistant PAEs could be stimulated by the addition of a degradable PAE. Synthesis of degradation intermediates and two methods for PAE analyses are presented. The investigation showed that all alcohols were degraded to methane and carbon dioxide and that the degradation of PAE occurred in incubations amended with BBP, BEHP, DHP and DBP, whilst DEHP, DOP and DDP were unaffected throughout the experimental period. BBP added to incubations with DEHP, could not stimulate DEHP degradation. In conclusion, the degradability of alcohols estrifying phthalic acid in this study does not affect the anaerobic degradability of PAEs. Water solubility of a PAE can not be rejected as a factor limiting phthalate degradation under methanogenic conditions. Anaerobic degradation of persistent PAEs can not be stimulated by mixing it with a degradable phthalate. 23 refs, 11 figs, 2 tabs

  6. Novel polysiloxane resin functionalized with dicyclohexano-18-crown-6 (DCH18C6): Synthesis, characterization and extraction of Sr(II) in high acidity HNO3 medium.

    Science.gov (United States)

    Ye, Gang; Bai, Feifei; Wei, Jichao; Wang, Jianchen; Chen, Jing

    2012-07-30

    A novel kind of polysiloxane resin functionalized with dicyclohexano-18-crown-6 (DCH18C6) was synthesized through a post-modification approach. The DCH18C6 moieties bearing amino groups were firstly prepared, followed by covalent grafting to a silica precursor P-(CH(2))(3)-Cl (Where P represents a 3-dimentional polymerized silica matrix) based on nucleophilic substitution reaction. (29)Si and (13)C solid-state NMR, FT-IR, XPS, TGA, ESEM and elemental analysis were employed to systematically characterize the structure, thermal property and surface morphology of the functionalized resin. The results indicated that the DCH18C6 ligands were successfully bonded to the polysiloxane resin with a satisfactory grafting degree (33.6wt.%). Due to the robust organosilica framework and the covalent immobilization of the ligands, the functionalized resin had excellent thermal stability and acid resistance. Batch experiments showed that the resin could effectively separate Sr(II) in high acidity mediums. The distribution coefficient (K(d)) of 43.6cm(3)/g could be achieved in 5.0mol/L HNO(3) solution. The influences of contact time and acidity of HNO(3) on the resin's extraction performance were examined. The reusability and the selectivity to Sr(II) over interference ions were investigated. The DCH18C6-functionalized resin might be potentially applied for the radiostrontium removal in the high level liquid waste (HLLW). Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Predicting the Viscosity of Low VOC Vinyl Ester and Fatty Acid-Based Resins

    National Research Council Canada - National Science Library

    LaScala, John J; Jeyarajasingam, Amutha; Winston, Cherise; Sand, James M; Palmese, Guiseppe R

    2005-01-01

    .... The viscosities of these resins were measured as a function of reactive diluent content and type, temperature, and vinyl ester molecular weight to determine the operating window for composite manufacture...

  8. Physical fertility of degraded acid sands in South-eastern Nigeria ...

    African Journals Online (AJOL)

    We evaluated the physical fertility of degraded and undegraded acid sands in Akwa Ibom State, South-eastern Nigeria. The soils were similar in texture, being predominantly sandy, averaging 90.1% in degraded and 89.9% in undegraded soil. Bulk density averaged 1.50g/cm3 and 1.45g/cm3, while macropores averaged ...

  9. [Effect of hydrofluoric acid etching time and resin bonding on the flexural strength of lithium disilicate glass ceramic].

    Science.gov (United States)

    Ren, Dong-feng; Luo, Xiao-ping

    2013-08-01

    To analyze the effect of hydrofluoric acid(HFA) etching time and resin bonding on the flexural strength of IPS e.max® Press glass ceramic, and evaluate the efficacy of resin cements to seal the cracks of the etched ceramic. Two hundred and twenty-five bars (25.0 mm×3.0 mm×2.0 mm) were made from IPS e.max® Press ingots using lost-wax, hot-pressed ceramic fabrication technology and randomly divided into five groups, forty-five each.In each group, the surfaces of ceramic bars were etched by 9.5% HFA gel for 0, 20, 40, 60 and 120 s respectively. Three specimens from each group were selected to observe the microstructure by the field emission scanning electron microscope (FE-SEM). Then each group were randomly subdivided into two subgroups (n = 20).One subgroup were coverd with a thin (approximately 0.1 mm) layer of resin cement (Variolink N), whereas the other subgroup remained unaltered.Half of the specimens were stored in 37°C water bath for 24 h and the other half went through thermocycle 10 000 times before 3-point bending test to determine their flexural strength.Interfaces between resin cement and etched ceramic were examined with FE-SEM. FE-SEM results showed that etching with HFA resulted in preferential dissolution of glass ceramic, and partially supported crystals within the glass matrix were lost with the increasing of etching time.FE-SEM indicated that resin cement sealed the cracks and defects and bonded tightly to etched ceramic surface. The mean flexural strength values of group 0, 20, 40, 60 and 120 s were (384 ± 33), (347 ± 43), (330 ± 53), (327 ± 67) , and (317 ± 41) MPa respectively. The mean flexural strength of each group except group 0 s increased significantly to (420 ± 31), (435 ± 50), (400 ± 39), and (412 ± 58) MPa respectively after the application of resin cement. Overtime HFA etching could have a wakening effect on IPS e.max® Press glass-ceramic. The application of dual-curing resin cement can compensate the strength loss of

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

    Directory of Open Access Journals (Sweden)

    M.S. Usha

    2010-12-01

    Full Text Available 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.

  11. Adipic acid degradation mechanism in aqueous fgd (flue gas desulfurization) systems. Final report Oct 78-Apr 79

    Energy Technology Data Exchange (ETDEWEB)

    Meserole, F.B.; Lewis, D.L.; Nichols, A.W.; Rochelle, G.

    1979-09-01

    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% of the adipic acid added to some systems is lost, supposedly through degradation.) The degradation is associated with the oxidation of sulfite, possibly through a free radical mechanism. At least one mechanism is an oxidative decarboxylation yielding valeric acid, butyric acid, glutaric acid, and CO2. The quantities of products measured during laboratory testing only account for approximately 30% of the adipic acid degraded.

  12. Mapping intermediate degradation products of poly(lactic-co-glycolic acid) in vitro.

    Science.gov (United States)

    Li, Jian; Nemes, Peter; Guo, Ji

    2018-04-01

    There is widespread interest in using absorbable polymers, such as poly(lactic-co-glycolic acid) (PLGA), as components in the design and manufacture of new-generation drug eluting stents (DES). PLGA undergoes hydrolysis to progressively degrade through intermediate chemical entities to simple organic acids that are ultimately absorbed by the human body. Understanding the composition and structure of these intermediate degradation products is critical not only to elucidate polymer degradation pathways accurately, but also to assess the safety and performance of absorbable cardiovascular implants. However, analytical approaches to determining the intermediate degradation products have yet to be established and evaluated in a standard or regulatory setting. Hence, we developed a methodology using electrospray ionization mass spectrometry to qualitatively and quantitatively describe intermediate degradation products generated in vitro from two PLGA formulations commonly used in DES. Furthermore, we assessed the temporal evolution of these degradation products using time-lapse experiments. Our data demonstrated that PLGA degradation products via heterogeneous cleavage of ester bonds are modulated by multiple intrinsic and environmental factors, including polymer chemical composition, degradants solubility in water, and polymer synthesis process. We anticipate the methodologies and outcomes presented in this work will elevate the mechanistic understanding of comprehensive degradation profiles of absorbable polymeric devices, and facilitate the design and regulation of cardiovascular implants by supporting the assessments of the associated biological response to degradation products. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1129-1137, 2018. © 2017 Wiley Periodicals, Inc.

  13. Adsorption and removal of clofibric acid and diclofenac from water with MIEX resin.

    Science.gov (United States)

    Lu, Xian; Shao, Yisheng; Gao, Naiyun; Chen, Juxiang; Zhang, Yansen; Wang, Qiongfang; Lu, Yuqi

    2016-10-01

    This study demonstrates the use of MIEX resin as an efficient adsorbent for the removal of clofibric acid (CA) and diclofenac (DCF). The adsorption performance of CA and DCF are investigated by a batch mode in single-component or bi-component adsorption system. Various factors influencing the adsorption of CA and DCF, including initial concentration, contact time, adsorbent dosage, initial solution pH, agitation speed, natural organic matter and coexistent anions are studied. The Langmuir model can well describe CA adsorption in single-component system, while the Freundlich model gives better fitting in bi-component system. The DCF adsorption can be well fitted by the Freundlich model in both systems. Thermodynamic analyses show that the adsorption of CA and DCF is an endothermic (ΔH(o) > 0), entropy driven (ΔS(o) > 0) process and more randomness exists in the DCF adsorption process. The values of Gibbs free energy (ΔG(o)  0) for CA adsorption. The kinetic data suggest the adsorption of CA and DCF follow the pseudo-first-order model in both systems and the intra-particle is not the unique rate-limiting step. The adsorption process is controlled simultaneously by external mass transfer and surface diffusion according to the surface diffusion modified Biot number (Bis) ranging from 1.06 to 26.15. Moreover, the possible removal mechanism for CA and DCF is respectively proposed based on the ion exchange stoichiometry. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Inhibition of Streptococcus mutans biofilm formation on composite resins containing ursolic acid

    Science.gov (United States)

    Kim, Soohyeon; Song, Minju; Roh, Byoung-Duck; Park, Sung-Ho

    2013-01-01

    Objectives To evaluate the inhibitory effect of ursolic acid (UA)-containing composites on Streptococcus mutans (S. mutans) biofilm. Materials and Methods Composite resins with five different concentrations (0.04, 0.1, 0.2, 0.5, and 1.0 wt%) of UA (U6753, Sigma Aldrich) were prepared, and their flexural strengths were measured according to ISO 4049. To evaluate the effect of carbohydrate source on biofilm formation, either glucose or sucrose was used as a nutrient source, and to investigate the effect of saliva treatment, the specimen were treated with either unstimulated whole saliva or phosphate-buffered saline (PBS). For biofilm assay, composite disks were transferred to S. mutans suspension and incubated for 24 hr. Afterwards, the specimens were rinsed with PBS and sonicated. The colony forming units (CFU) of the disrupted biofilm cultures were enumerated. For growth inhibition test, the composites were placed on a polystyrene well cluster, and S. mutans suspension was inoculated. The optical density at 600 nm (OD600) was recorded by Infinite F200 pro apparatus (TECAN). One-way ANOVA and two-way ANOVA followed by Bonferroni correction were used for the data analyses. Results The flexural strength values did not show significant difference at any concentration (p > 0.01). In biofilm assay, the CFU score decreased as the concentration of UA increased. The influence of saliva pretreatment was conflicting. The sucrose groups exhibited higher CFU score than glucose group (p composite showed inhibitory effect on S. mutans biofilm formation and growth. PMID:23741708

  15. Influence of humic acid on the trichloroethene degradation by Dehalococcoides-containing consortium

    International Nuclear Information System (INIS)

    Hu Miao; Zhang Ying; Wang Zhigang; Jiang Zhao; Li Juan

    2011-01-01

    By taking an anaerobic Dehalococcoides-containing consortium (designated UC-1) as the research object, the influence of humic acid on the degradation of TCE by UC-1 was examined. The results indicated that (i) TCE was more rapidly degraded in the presence of humic acid compared with the control and the TCE removal efficiencies increased with the increase of concentrations of humic acid; and (ii) at the end of experiments, in the presence of humic acid, much more ethene was produced compared with the control, whereas less VC was accumulated in the medium. Presumably, humic acid improves the activity of organisms in dechlorinating populations resulting in more ethene accumulated in the medium, and (iii) the degradation of TCE stimulated by humic acid by UC-1 might be a biotic process or an abiotic process. Thus, humic acid could influence the degradation of TCE by UC-1 directly via enhancing electron transfer between UC-1 and TCE. This work is a preliminary step for accelerating the degradation of TCE in the groundwater environment using a kind of natural organic matter - humic acid.

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

    International Nuclear Information System (INIS)

    Bellocco, E.; Barreca, D.; Lagana, G.; Leuzzi, U.; Migliardo, F.; Torre, R. La; Galli, G.; Galtieri, A.; Minutoli, L.; Squadrito, F.

    2008-01-01

    The present paper shows a systematic dynamic and kinetic study on L-ascorbic acid and its degradation at high temperature. The neutron scattering study allows, through the behavior of quasi-elastic neutron scattering (QENS) spectra, to characterize the diffusive dynamics of L-ascorbic acid in water mixtures. Ascorbic acid undergoes degradation process at high temperature, but the presence of trehalose in solution markedly avoids ascorbic acid loss enhancing its t 1/2 (half life time), as determined by high performance liquid chromatography (HPLC)

  17. In vivo and in vitro evaluation of the efficacy of a peracetic acid-based disinfectant for decontamination of acrylic resins.

    Science.gov (United States)

    Chassot, Ana Lúcia Campani; Poisl, Maria Inês Pereira; Samuel, Susana Maria Werner

    2006-01-01

    The purpose of this study was to assess the antimicrobial efficacy of a peracetic acid-based disinfectant for decontamination of heat-polymerized, chemically activated and microwave-polymerized acrylic resins. Resin plates were contaminated in vivo upon intraoral use by 10 volunteers for 7 nights and slabs were contaminated in vitro by contact with Bacillus subtilis and Bacillus stearothermophilus. The contaminated acrylic resin specimens were immersed in a 0.2% peracetic acid-based disinfectant (Sterilife; Lifemed) for 5 min or 10 min and placed in a BHI culture medium. After incubation at 37 degrees C for 48 h, bacterial growth was assessed by analyzing turbidity of the medium. For all types of acrylic resin, no turbidity of the medium was observed for any of the resin specimens immersed in the peracetic acid-based disinfectant for either 5 or 10 min. On the other hand, the media with specimens that were not immersed in the disinfectant (control) showed turbidity in 100% of the cases, indicating the presence of microorganisms in both tested conditions. In conclusion, immersion for at least 5 min in a 0.2% peracetic acid-based disinfectant promoted high-level disinfection of heat-polymerized, chemically activated and microwave-polymerized acrylic resins contaminated with either human saliva or Bacillus subtilis or Bacillus stearothermophilus.

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

    Science.gov (United States)

    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. Copyright © 2014 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    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.

  20. Modelling of thermal degradation kinetics of ascorbic acid in ...

    African Journals Online (AJOL)

    Ascorbic acid (vitamin C) loss in thermally treated pawpaw and potato was modelled mathematically. Isothermal experiments in the temperature range of 50 -80 oC for the drying of pawpaw and 60 -100 oC for the blanch-drying of potato were utilized to determine the kinetics of ascorbic acid loss in both fruit and vegetable.

  1. Modelling of Thermal Degradation Kinetics of Ascorbic Acid in ...

    African Journals Online (AJOL)

    Ascorbic acid (vitamin C) loss in thermally treated pawpaw and potato was modelled mathematically. Isothermal experiments in the temperature range of 50 -80 oC for the drying of pawpaw and 60 -100 oC for the blanch-drying of potato were utilized to determine the kinetics of ascorbic acid loss in both fruit and vegetable.

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

    DEFF Research Database (Denmark)

    Hawkins, C L; Davies, Michael Jonathan

    1998-01-01

    Degradation of hyaluronic acid by oxidants such as HO. and HOCl/CIO- is believed to be important in the progression of rheumatoid arthritis. While reaction of hyaluronic acid with HO. has been investigated extensively, reaction with HOCl/ClO- is less well defined. Thus, little is known about the ...

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

    Directory of Open Access Journals (Sweden)

    MEHDI GHASEMI

    2015-04-01

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

  4. Quantitative analysis of Loperamide hydrochloride in the presence its acid degradation products

    Directory of Open Access Journals (Sweden)

    Savić Ivana M.

    2009-01-01

    Full Text Available The aim of this work was to develop a new RP-HPLC method for the determination of loperamide hydrochloride in the presence of its acid degradation products. Separation of loperamide from degradation products was performed using ZORBAX Eclipse XDB C-18, column with a mobile phase consisting of 0.1% sodium-octansulphonate, 0.05% triethylamine, 0.1% ammonium hydroxide in water:acetonitrile (45:55 v/v. The mobile phase was adjusted to pH 3.2 with phosphoric acid. The method showed high sensitivity with good linearity over the concentration range of 10 to 100 μg cm-3. The method was successfully applied to the analysis of a pharmaceutical formulation (Loperamide, Zdravlje-Actavis, Serbia containing loperamide hydrochloride with excellent recovery. The loperamide hydrochloride degradation during acid hydrolysis and kinetics investigation was carried out in hydrochloric acid solutions of 0.1, 1.0 and 1.5 mol dm-3, at different temperatures (25 and 40°C, by monitoring the parent compound itself. The first order reaction of loperamide degradation in acid solution was determined. The activation energy was estimated from the Arrhenius plot and it was found to be 38.81 kJ mol-1 at 40°C. The developed procedure was successfully applied for the rapid determination of loperamide hydrochloride in pharmaceutical formulation (Loperamide, Zdravlje-Actavis, Serbia and in the presence of its acid degradation products.

  5. Effects of the peracetic acid and sodium hypochlorite on the colour stability and surface roughness of the denture base acrylic resins polymerised by microwave and water bath methods.

    Science.gov (United States)

    Fernandes, Flavio H C N; Orsi, Iara A; Villabona, Camilo A

    2013-03-01

    This study evaluated the surface roughness (Ra) and color stability of acrylic resin colors (Lucitone 550, QC-20 and Vipi-Wave) used for fabricating bases for complete, removable dentures, overdentures and prosthetic protocol after immersion in chemical disinfectants (1% sodium hypochlorite and 2% peracetic acid) for 30 and 60 minutes. Sixty specimens were made of each commercial brand of resin composite, and divided into 2 groups according to the chemical disinfectants. Specimens had undergone the finishing and polishing procedures, the initial color and roughness measurements were taken (t=0), and after this, ten test specimens of each commercial brand of resin composite were immersed in sodium hypochlorite and ten in peracetic acid, for 30 and 60 minutes, with measurements being taken after each immersion period. These data were submitted to statistical analysis. There was evidence of an increase in Ra after 30 minutes immersion in the disinfectants in all the resins, with QC-20 presenting the highest Ra values, and Vipi-Wave the lowest. After 60 minutes immersion in the disinfectants all the resins presented statistically significant color alteration. Disinfection with 1% sodium hypochlorite and peracetic acid altered the properties of roughness and color of the resins. © 2012 The Gerodontology Society and John Wiley & Sons A/S.

  6. An investigation about the solid state thermal degradation of acetylsalicylic acid: polymer formation

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Edna M. de A; Melo, Dulce M. de A; Moura, Maria de F.V. de; Farias, Robson F. de

    2004-05-06

    An investigation about the thermal degradation of acetylsalicylic acid (ASA) is performed. It is verified that the thermal degradation of ASA produces not only salicylic acid (SA) and acetic acid (AA) as products but also an ASA polymer, which is transparent and solid. And also verified that the temperature in which the polymer is obtained influences its physical consistence (solid or semi-solid). Furthermore, the ASA polymer is very stable from a thermic point of view, as verified by TG and DSC analysis. X-ray diffraction patterns obtained for the ASA polymer show that it exhibits a low crystallinity.

  7. Isolation and characterization of isopimaric acid-degrading bacteria from a sequencing batch reactor.

    Science.gov (United States)

    Wilson, A E; Moore, E R; Mohn, W W

    1996-09-01

    We isolated two aerobic, gram-negative bacteria which grew on the diterpene resin acid isopimaric acid (IpA) as the sole carbon source and electron donor. The source of the isolates was a sequencing batch reactor treating a high-strength process stream from a paper mill. The isolates, IpA-1 and IpA-2, also grew on pimaric and dehydroabietic acids, and IpA-1 grew on abietic acid. Both strains used fatty acids, but neither strain used camphor, sitosterol, or betulin. Strain IpA-1 grew anaerobically with nitrate as an electron acceptor. Strains IpA-1 and IpA-2 had growth yields of 0.19 and 0.23 g of protein per g of IpA, respectively. During growth, both strains transformed IpA carbon to approximately equal amounts of biomass, carbon dioxide, and dissolved organic carbon. In both strains, growth on IpA induced an enzymatic system which caused cell suspensions to transform all four of the above resin acids. Cell suspensions of IpA-1 and IpA-2 removed IpA at rates of 0.56 and 0.13 mumol mg of protein-1 h-1, respectively. Cultures and cell suspensions of both strains failed to completely consume pimaric acid and yielded small amounts of an apparent metabolite from this acid. Cultures and cell suspensions of both strains yielded large amounts of three apparent metabolites from dehydroabietic acid. Analysis of 16S rDNA sequences indicated that the isolates are distinct members of the genus Pseudomonas sensu stricto.

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

    Czech Academy of Sciences Publication Activity Database

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

    2007-01-01

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

  9. Rapid Degradation of Auxin/Indoleacetic Acid Proteins Requires Conserved Amino Acids of Domain II and Is Proteasome Dependent

    Science.gov (United States)

    Ramos, Jason A.; Zenser, Nathan; Leyser, Ottoline; Callis, Judy

    2001-01-01

    Auxin rapidly induces auxin/indoleacetic acid (Aux/IAA) transcription. The proteins encoded are short-lived nucleus-localized transcriptional regulators that share four conserved domains. In a transient assay measuring protein accumulation, an Aux/IAA 13–amino acid domain II consensus sequence was sufficient to target firefly luciferase (LUC) for low protein accumulation equivalent to that observed previously for full-length PSIAA6. Single amino acid substitutions in these 13 amino acids, corresponding to known auxin response mutants, resulted in a sixfold to 20-fold increase in protein accumulation. Naturally occurring variant amino acids had no effect. Residues identified as essential by single alanine substitutions were not sufficient when all flanking amino acids were alanine, indicating the importance of flanking regions. Using direct protein degradation measurements in transgenic Arabidopsis seedlings, full-length IAA1, PSIAA6, and the N-terminal 73 PSIAA6 amino acids targeted LUC for rapid degradation with 8-min half-lives. The C-terminal 109 amino acids did not affect LUC half-life. Smaller regions containing domain II also targeted LUC for rapid degradation, but the rates were not equivalent to those of the full-length protein. A single domain II substitution in the context of full-length PSIAA6 increased half-life 30-fold. Proteasome inhibitors affected Aux/IAA::LUC fusion protein accumulation, demonstrating the involvement of the proteasome. PMID:11595806

  10. Degradation Behaviour of Gamma Irradiated Poly(Acrylic Acid)-graft-Chitosan Superabsorbent Hydrogel

    Science.gov (United States)

    Ria Barleany, Dhena; Ilhami, Alpin; Yusuf Yudanto, Dea; Erizal

    2018-03-01

    A series of superabsorbent hydrogels were prepared from chitosan and partially neutralized acrylic acid at room temperature by gamma irradiation technique. The effect of irradiation and chitosan addition to the degradation behaviour of polymer were investigated. The gel content, swelling capacity, Equillibrium Degree of Swelling (EDS), Fourier Transform Infra Red (FTIR), and Scanning Electron Microscopy (SEM) study were also performed. Natural degradation in soil and thermal degradation by using of TGA analysis were observed. The variation of chitosan compositions were 0.5, 1, 1.5, and 2 g and the total irradiation doses were 5, 10, 15, and 20 kGy. The highest water capacity of 583.3 g water/g dry hydrogel was resulted from 5 kGy total irradiation dose and 0,5 g addition of chitosan. From the thermal degradation evaluation by using of TGA analysis showed that irradiation dose did not give a significant influence to the degradation rate. The rate of thermal degradation was ranged between 2.42 to 2.55 mg/min. In the natural test of degradation behaviour by using of soil medium, the hydrogel product with chitosan addition was found to have better degradability compared with the poly(acrylic acid) polymer without chitosan.

  11. The bile acid-sequestering resin sevelamer eliminates the acute GLP-1 stimulatory effect of endogenously released bile acids in patients with type 2 diabetes

    DEFF Research Database (Denmark)

    Brønden, Andreas; Albér, Anders; Rohde, Ulrich

    2018-01-01

    of the present study was to assess the GLP-1 secretory and gluco-metabolic effects of endogenously released bile, with and without concomitant administration of the bile acid-sequestering resin, sevelamer, in patients with type 2 diabetes. MATERIALS AND METHODS: We performed a randomized, placebo......-controlled, and double-blinded cross-over study including 15 metformin-treated patients with type 2 diabetes. Four experimental study days in randomized order with administration of either sevelamer 3,200 mg or placebo in combination with intravenous infusion of cholecystokinin (CCK) (0.4 pmol sulfated CCK-8/kg...... was shown to eliminate the acute bile acid-induced increase in plasma GLP-1 excursions. CONCLUSIONS: Single-dose administration of sevelamer eliminated bile acid-mediated GLP-1 secretion in patients with type 2 diabetes, which could be explained by reduced bile acid stimulation of the basolaterally...

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

    Science.gov (United States)

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

    2016-01-01

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

  13. Changes in volatile terpene and diterpene resin acid composition of resistant and susceptible white spruce leaders exposed to simulated white pine weevil damage.

    Science.gov (United States)

    Tomlin, E S; Antonejevic, E; Alfaro, R I; Borden, J H

    2000-10-01

    Induced (traumatic) resin in white spruce (Picea glauca (Moench) Voss) leaders resistant or susceptible to the white pine weevil (Pissodes strobi Peck) was analyzed for volatile terpenes and diterpene resin acids after simulated white pine weevil damage. Leaders from 331 trees were wounded just below the apical bud with a 1-mm diameter drill, coinciding with the natural time of weevil oviposition in the spring. Leaders were removed in the fall, and the bark and xylem from the upper and lower regions of the leader extracted and analyzed by gas chromatography. Unwounded trees had low amounts of resin in xylem compared with bark. In response to wounding, volatile terpenes and diterpene resin acids increased in the upper xylem (area of wounding), with resistant trees showing a greater increase than susceptible trees. Wounding caused monoterpenes in particular to decrease in the lower region of the leader (away from the drilled area) in greater amounts in susceptible trees than in resistant trees. In response to wounding, the proportion of monoterpene to resin acid increased in the upper and lower xylem of resistant trees, and slightly increased in the upper xylem of susceptible trees. Monoterpene-enriched resin is more fluid than constitutive resin, and probably flows more readily into oviposition cavities and larval mines, where it may kill immature weevils. Loss of resin components in the lower xylem suggested catabolism and transport of these materials to the site of wounding; however, energetic and regulatory data are necessary to confirm this hypothesis. This study provides a basis for measuring the ability of a tree to undergo traumatic resinosis that could be used to screen for resistance to white pine weevil.

  14. Experimental investigation of the degradation rate of adipic acid in wet flue gas desulphurisation plants

    Energy Technology Data Exchange (ETDEWEB)

    Christian N. Buchardt; Jan Erik Johnsson; Soeren Kiil [Technical University of Denmark, Lyngby (Denmark). Department of Chemical Engineering

    2006-03-15

    The aim of this work is to study the degradation rate of adipic acid in wet FGD plants using forced oxidation. The investigation is experimentally demanding because the degradation rate must be studied under realistic conditions present in pilot plants or industrial plants only. This is the first systematic investigation including both chemical and biological degradation. The influence on the degradation rate of adipic acid was studied: The concentration of adipic acid (0-2100 mg/l), trace-metals, Cl{sup -} (0-50 g/l), pH (4.7 and 5.4), and temperature (32, 42 and 50{sup o}C). Furthermore, the degradation rate of adipic acid was examined in two types of limestone/gypsum slurry: one based on limestone, distilled water and flue gas from natural gas combustion, the other on slurry liquid taken from the wet FGD plant of a full-scale power plant (coal combustion) with limestone subsequently added. The first order rate constant, using slurry based on natural gas combustion, was estimated to 0.60{+-}0.10 day{sup -1} which is more than twice the value of the rate constant estimated from experiments based on slurry from the full-scale wet FGD plant (0.25{+-}0.10 day{sup -1}). Both types of slurry were examined for biological activity. In the slurry based on natural gas combustion no biological activity was found. Independent laboratory tests showed that biological activity contributed to the degradation rate of adipic acid in the slurry liquid from the full-scale wet FGD plant, though the effect could not be quantified. Analysis of the slurries for selected trace metals showed significantly higher concentrations in the slurry from the full-scale plant. It was found that increasing concentrations of trace metals and chloride inhibits the chemical degradation of adipic acid. 19 refs., 10 figs., 7 tabs.

  15. Conifer Diterpene Resin Acids Disrupt Juvenile Hormone-Mediated Endocrine Regulation in the Indian Meal Moth Plodia interpunctella.

    Science.gov (United States)

    Oh, Hyun-Woo; Yun, Chan-Seok; Jeon, Jun Hyoung; Kim, Ji-Ae; Park, Doo-Sang; Ryu, Hyung Won; Oh, Sei-Ryang; Song, Hyuk-Hwan; Shin, Yunhee; Jung, Chan Sik; Shin, Sang Woon

    2017-07-01

    Diterpene resin acids (DRAs) are important components of oleoresin and greatly contribute to the defense strategies of conifers against herbivorous insects. In the present study, we determined that DRAs function as insect juvenile hormone (JH) antagonists that interfere with the juvenile hormone-mediated binding of the JH receptor Methoprene-tolerant (Met) and steroid receptor coactivator (SRC). Using a yeast two-hybrid system transformed with Met and SRC from the Indian meal moth Plodia interpunctella, we tested the interfering activity of 3704 plant extracts against JH III-mediated Met-SRC binding. Plant extracts from conifers, especially members of the Pinaceae, exhibited strong interfering activity, and four active interfering DRAs (7α-dehydroabietic acid, 7-oxodehydroabietic acid, dehydroabietic acid, and sandaracopimaric acid) were isolated from roots of the Japanese pine Pinus densiflora. The four isolated DRAs, along with abietic acid, disrupted the juvenile hormone-mediated binding of P. interpunctella Met and SRC, although only 7-oxodehydroabietic acid disrupted larval development. These results demonstrate that DRAs may play a defensive role against herbivorous insects via insect endocrine-disrupting activity.

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

    International Nuclear Information System (INIS)

    Palfi, T.; Homlok, R.; Csay, T.; Wojnarovits, L.; Takacs, E.

    2011-01-01

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

  17. Long term stability of cannabis resin and cannabis extracts

    DEFF Research Database (Denmark)

    Lindholst, Christian

    2010-01-01

    at room temperature, 4 °C and - 20 °C for up to 4 years. Acidic THC degrades exponentially via decarboxylation with concentration halve-lives of approximately 330 and 462 days in daylight and darkness, respectively. The degradation of neutral THC seems to occur somewhat slower. When cannabinoids were...... stored in extracted form at room temperature the degradation rate of acidic THC increased significantly relative to resin material with concentration halve-lives of 35 and 91 days in daylight and darkness, respectively. Once cannabis material is extracted into organic solvents, care should be taken...

  18. Synthetic resin-bound truncated Candida antarctica lipase B for production of fatty acid alkyl esters by transesterification of corn and soybean oils with ethanol or butanol.

    Science.gov (United States)

    Hughes, Stephen R; Moser, Bryan R; Robinson, Samantha; Cox, Elby J; Harmsen, Amanda J; Friesen, Jon A; Bischoff, Kenneth M; Jones, Marjorie A; Pinkelman, Rebecca; Bang, Sookie S; Tasaki, Ken; Doll, Kenneth M; Qureshi, Nasib; Liu, Siqing; Saha, Badal C; Jackson, John S; Cotta, Michael A; Rich, Joseph O; Caimi, Paolo

    2012-05-31

    A gene encoding a synthetic truncated Candida antarctica lipase B (CALB) was generated via automated PCR and expressed in Saccharomyces cerevisiae. Western blot analysis detected five truncated CALB variants, suggesting multiple translation starts from the six in-frame ATG codons. The longest open reading frame, which corresponds to amino acids 35-317 of the mature lipase, appeared to be expressed in the greatest amount. The truncated CALB was immobilized on Sepabeads® EC-EP resin and used to produce ethyl and butyl esters from crude corn oil and refined soybean oil. The yield of ethyl esters was 4-fold greater from corn oil than from soybean oil and was 36% and 50% higher, respectively, when compared to a commercially available lipase resin (Novozym 435) using the same substrates. A 5:1 (v/v) ratio of ethanol to corn oil produced 3.7-fold and 8.4-fold greater yields than ratios of 15:1 and 30:1, respectively. With corn oil, butyl ester production was 56% higher than ethyl ester production. Addition of an ionic catalytic resin step prior to the CALB resin increased yields of ethyl esters from corn oil by 53% compared to CALB resin followed by ionic resin. The results suggest resin-bound truncated CALB has potential application in biodiesel production using biocatalysts. Published by Elsevier B.V.

  19. Degradation of protein translation machinery by amino acid starvation-induced macroautophagy.

    Science.gov (United States)

    Gretzmeier, Christine; Eiselein, Sven; Johnson, Gregory R; Engelke, Rudolf; Nowag, Heike; Zarei, Mostafa; Küttner, Victoria; Becker, Andrea C; Rigbolt, Kristoffer T G; Høyer-Hansen, Maria; Andersen, Jens S; Münz, Christian; Murphy, Robert F; Dengjel, Jörn

    2017-06-03

    Macroautophagy is regarded as a nonspecific bulk degradation process of cytoplasmic material within the lysosome. However, the process has mainly been studied by nonspecific bulk degradation assays using radiolabeling. In the present study we monitor protein turnover and degradation by global, unbiased approaches relying on quantitative mass spectrometry-based proteomics. Macroautophagy is induced by rapamycin treatment, and by amino acid and glucose starvation in differentially, metabolically labeled cells. Protein dynamics are linked to image-based models of autophagosome turnover. Depending on the inducing stimulus, protein as well as organelle turnover differ. Amino acid starvation-induced macroautophagy leads to selective degradation of proteins important for protein translation. Thus, protein dynamics reflect cellular conditions in the respective treatment indicating stimulus-specific pathways in stress-induced macroautophagy.

  20. modelling of thermal degradation kinetics of ascorbic acid

    African Journals Online (AJOL)

    Administrator

    nutritional importance of antioxidants in foods such as ascorbic acid (vitamin C) has found increased interest due to their possible role in the prevention of human diseases such as cancer, atherosclerosis and immune depression (Byres and Perry, 1992). The status of vitamins during processing is receiving more attention. A.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

    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

  3. Ion Exchange Study of Some New Copolymer Resins Derived from 8-Hydroxyquinoline-5-sulphonic Acid, Biuret and Formaldehyde

    Directory of Open Access Journals (Sweden)

    P. A. Dhakite

    2011-01-01

    Full Text Available Copolymer resins (8-HQSABF were synthesized by the condensation of 8-hydroxyquinoline-5-sulphonic acid and biuret with formaldehyde in the presence of hydrochloric acid as catalyst, proved to be selective chelation ion exchange copolymer resins for certain metals. Chelation ion exchange properties to these polymers were studied for Cu2+, Cd2+, Co2+ and Zn2+ ions. A batch equilibrium method was employed in the study of the selectivity of the distribution of a given metal ions between the polymer sample and a solution containing the metal ion. The study was carried out over a wide pH range and in a media of various ions strengths. The polymer showed a higher selectivity for Cu2+ ions than for Cd2+, Co2+ and Zn2+ ions. Hence on the basis of above studies these copolymer may be used as semiconductors, surface coating, ion-exchangers, materials for rechargeable battery cell in various electronic industries, plastic materials, elastomers and in boiler plants

  4. A Robust Epoxy Resins @ Stearic Acid-Mg(OH)2 Micronanosheet Superhydrophobic Omnipotent Protective Coating for Real-Life Applications.

    Science.gov (United States)

    Si, Yifan; Guo, Zhiguang; Liu, Weimin

    2016-06-29

    Superhydrophobic coating has extremely high application value and practicability. However, some difficult problems such as weak mechanical strength, the need for expensive toxic reagents, and a complex preparation process are all hard to avoid, and these problems have impeded the superhydrophobic coating's real-life application for a long time. Here, we demonstrate one kind of omnipotent epoxy resins @ stearic acid-Mg(OH)2 superhydrophobic coating via a simple antideposition route and one-step superhydrophobization process. The whole preparation process is facile, and expensive toxic reagents needed. This omnipotent coating can be applied on any solid substrate with great waterproof ability, excellent mechanical stability, and chemical durability, which can be stored in a realistic environment for more than 1 month. More significantly, this superhydrophobic coating also has four protective abilities, antifouling, anticorrosion, anti-icing, and flame-retardancy, to cope with a variety of possible extreme natural environments. Therefore, this omnipotent epoxy resins @ stearic acid-Mg(OH)2 superhydrophobic coating not only satisfies real-life need but also has great application potential in many respects.

  5. Fluorescence Spectroscopy Applied to Monitoring Biodiesel Degradation: Correlation with Acid Value and UV Absorption Analyses

    Directory of Open Access Journals (Sweden)

    Maydla dos Santos Vasconcelos

    2018-01-01

    Full Text Available The techniques used to monitor the quality of the biodiesel are intensely discussed in the literature, partly because of the different oil sources and their intrinsic physicochemical characteristics. This study aimed to monitor the thermal degradation of the fatty acid methyl esters of Sesamum indicum L. and Raphanus sativus L. biodiesels (SILB and RSLB, resp.. The results showed that both biodiesels present a high content of unsaturated fatty acids, ∼84% (SILB and ∼90% (RSLB. The SILB had a high content of polyunsaturated linoleic fatty acid (18  :  2, about 49%, and the oleic monounsaturated (18  :  1, ∼34%. On the other hand, RSLB presented a considerable content of linolenic fatty acid (18  :  3, ∼11%. The biodiesel samples were thermal degraded at 110°C for 48 hours, and acid value, UV absorption, and fluorescence spectroscopy analysis were carried out. The results revealed that both absorption and fluorescence presented a correlation with acid value as a function of degradation time by monitoring absorptions at 232 and 270 nm as well as the emission at 424 nm. Although the obtained correlation is not completely linear, a direct correlation was observed in both cases, revealing that both properties can be potentially used for monitoring the biodiesel degradation.

  6. TiO(2)-assisted photocatalytic degradation of humic acids: effect of copper ions.

    Science.gov (United States)

    Uyguner, C S; Bekbolet, M

    2010-01-01

    The present study investigated the removal efficiency of aqueous humic acid solutions by TiO(2) photocatalytic degradation in the presence of Cu(II) species. The pseudo-first-order kinetics revealed rate constants as 9.87 x 10(-3), 7.19 x 10(-3), 3.81 x 10(-3) min(-1) for Color(436), UV(254) and TOC, respectively. Comparatively, lower rate constants were attained with respect to photocatalytic degradation of humic acid. Considering the source-dependent diverse chemical and spectral characteristics of NOM, a particular interaction would be expected for humic acid with Cu(II) species (0.1 mg L(-1)). The presence of copper ions significantly altered the photocatalytic degradation kinetics of humic acids in relation to the concentration effects of humic acid as expressed by spectroscopic parameters and TOC. Batch equilibrium adsorption experiments revealed a distinct Langmuirian-type adsorptive behavior of humic acid onto TiO(2) both in terms of UV(254) and Color(436) and a C-type adsorption isotherm was attained for TOC. K(F) values displayed an inconsistent effect of Cu(II) species, while adsorption intensity factor 1/ncopper ions and humic molecular size fractions, spectroscopic techniques were also employed for the assessment of the adsorption as well as photocatalytic degradation efficiencies.

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

    DEFF Research Database (Denmark)

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

    2014-01-01

    Degradation tests of two phosphoric acid (PA) doped PBI membrane based HT-PEM fuel cells were reported in this paper to investigate the effects of start/stop and the presence of methanol in the fuel to the performance degradation. Continuous tests with H2 and simulated reformate which was composed...... to the redistribution of PA between the membrane and electrodes. EIS measurement of first fuel cell during the start/stop test showed that the mass transfer resistance and ohmic resistance increased which can be attributed to the corrosion of carbon support in the catalyst layer and degradation of the PBI membrane...

  8. Kinetics of Maleic Acid and Aluminum Chloride Catalyzed Dehydration and Degradation of Glucose

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Ximing; Hewetson, Barron B.; Mosier, Nathan S.

    2015-04-16

    We report the positive effect of maleic acid, a dicarboxylic acid, on the selectivity of hexose dehydration to 5-hydroxymethyfurfural (HMF) and subsequent hydrolysis to levulinic and formic acids. We also describe the kinetic analysis of a Lewis acid (AlCl3) alone and in combination with HCl or maleic acid to catalyze the isomerization of glucose to fructose, dehydration of fructose to HMF, hydration of HMF to levulinic and formic acids, and degradation of these compounds to humins. The results show that AlCl3 significantly enhances the rate of glucose conversion to HMF and levulinic acid in the presence of both maleic acid and HCl. In addition, the degradation of HMF to humins, rather than levulinic and formic acids, is reduced by 50% in the presence of maleic acid and AlCl3 compared to HCl combined with AlCl3. The results suggest different reaction mechanisms for the dehydration of glucose and rehydration of HMF between maleic acid and HCl.

  9. Calcium isotope fractionation in liquid chromatography with benzo-18-crown-6 resin in aqueous hydrobromic acid medium

    International Nuclear Information System (INIS)

    Sato, Takuya; Oi, Takao

    2015-01-01

    Liquid chromatography operated in a breakthrough mode was employed to study calcium isotope fractionation in the aqueous hydrobromic acid medium. Highly porous silica beads, the inner pores of which were embedded with a benzo-18-crown-6 ether resin, were used as column packing material. Enrichment of heavier isotopes of calcium was observed in the frontal part of respective calcium chromatograms. The values of the isotope fractionation coefficient were on the order of 10 -3 . The observed isotope fractionation coefficient was dependent on the concentration of hydrobromic acid in the calcium feed solution; a higher HBr concentration resulted in a smaller fractionation coefficient value. The present calcium isotope effects were most probably mass-dependent, indicating that they mostly came from isotope effects based on molecular vibration. Molecular orbital calculations supported the present experimental results in a qualitative fashion. Chromatography operated in aqueous HBr media is a better system of Ca isotope separation than that operated in aqueous HCl media. (author)

  10. Rapid degradation of 2,4-dichlorophenoxyacetic acid facilitated by acetate under methanogenic condition.

    Science.gov (United States)

    Yang, Zhiman; Xu, Xiaohui; Dai, Meng; Wang, Lin; Shi, Xiaoshuang; Guo, Rongbo

    2017-05-01

    Acetate can be used as an electron donor to stimulate 2,4-dichlorophenoxyacetic acid (2,4-D), which has not been determined under methanogenic condition. This study applied high-throughput sequencing and methanogenic inhibition approaches to investigate the 2,4-D degradation process using the enrichments obtained from paddy soil. Acetate addition significantly promoted 2,4-D degradation, which was 5-fold higher than in the acetate-unsupplemented enrichments in terms of the 2,4-D degradation rate constant. Dechloromonas and Pseudomonas were the dominant 2,4-D degraders. Methanogenic inhibition experiments indicated that the 2,4-D degradation was independent of methanogenesis. It was proposed that the accelerated 2,4-D degradation in the acetate-supplemented enrichment involved an unusual interaction, where members of the acetate oxidizers primarily oxidized acetate and produced H 2 . H 2 was utilized by the 2,4-D degraders to degrade 2,4-D, but also partially consumed by the hydrogenotrophic methanogens to produce methane. The findings presented here provide a new strategy for the remediation of 2,4-D-polluted soils. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

    Directory of Open Access Journals (Sweden)

    Xiaoyu Wang

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

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

    Science.gov (United States)

    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. © 2015 SETAC.

  13. Input to Resin Column Structural Analysis if Autocatalytic Resin Reaction Occurs in HB-Line Phase II

    Energy Technology Data Exchange (ETDEWEB)

    Hallman, D.F.

    2001-07-10

    Solutions of plutonium in nitric acid are purified and concentrated using anion resin prior to precipitation. There have been instances of resin column explosions caused by autocatalytic reactions of anion resins in nitric acid within the DOE complex

  14. Esterification of oleic acid in a three-phase, fixed-bed reactor packed with a cation exchange resin catalyst.

    Science.gov (United States)

    Son, Sung Mo; Kimura, Hiroko; Kusakabe, Katsuki

    2011-01-01

    Esterification of oleic acid was performed in a three-phase fixed-bed reactor with a cation exchange resin catalyst (Amberlyst-15) at high temperature, which was varied from 80 to 120 °C. The fatty acid methyl ester (FAME) yields in the fixed-bed reactor were increased with increases in the reaction temperature, methanol flow rate and bed height. Moreover, the FAME yields were higher than those obtained using a batch reactor due to an equilibrium shift toward the product that resulted from continuous evaporation of the produced water. In addition, there was no catalyst deactivation during the esterification of oleic acid. However, addition of sunflower oil to the oleic acid reduced the FAME yield obtained from simultaneous esterification and transesterification. The FAME yield was 97.5% at a reaction temperature of 100 °C in the fixed-bed with a height of 5 cm when the methanol and oleic acid feed rates were 8.6 and 9.0 mL/h, respectively. Copyright © 2010 Elsevier Ltd. All rights reserved.

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

    International Nuclear Information System (INIS)

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

    2012-01-01

    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. - Highlights: ► We investigated the degradation of folic acid aqueous solution after electron beam treatment. ► Radiation doses over 5 kGy promote huge folic acid degradation and appearance of several degradation products. ► PCA, PABA and pABGA, already known folic acid degradation products, are formed due to E-beam treatment. ► Xanthopterin, a new radio-induced breakdown product, is formed after irradiation treatment.

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

    Energy Technology Data Exchange (ETDEWEB)

    Krimmel, Birgit; Swoboda, Friederike [University of Vienna, Department of Nutritional Sciences, Section Radiation Biology (Austria); Solar, Sonja, E-mail: sonja.solar@univie.ac.a [University of Vienna, Department of Nutritional Sciences, Section Radiation Biology (Austria); Reznicek, Gottfried [Department of Pharmacognosy, Althanstrasse 14, A-1090 Vienna (Austria)

    2010-12-15

    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{sub 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.

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

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

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

    2010-01-01

    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.

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

    DEFF Research Database (Denmark)

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

    1999-01-01

    The aim of this study was to investigate whether prolonged one-leg knee-extensor exercise enhances net protein degradation in muscle with a normal or low glycogen content. Net amino acid production, as a measure of net protein degradation, was estimated from leg exchange and from changes...... acid production was also 10-fold higher during exercise compared with that at rest (difference not significant). The net production rates of threonine, glycine and tyrosine and of the sum of the non-metabolized amino acids were about 1.5-2.5-fold higher during exercise with the leg with a low glycogen...... in the concentrations of amino acids that are not metabolized in skeletal muscle. Experiments were performed at rest and during one-leg knee-extensor exercise in six subjects having one leg with a normal glycogen content and the other with a low glycogen content. Exercise was performed for 90 min at a workload of 60...

  20. Iridium nanoparticles with high catalytic activity in degradation of acid red-26: an oxidative approach.

    Science.gov (United States)

    Goel, Anjali; Lasyal, Rajni

    2016-12-01

    Nanocatalysis using metal nanoparticles constitutes one of the emerging technologies for destructive oxidation of organics such as dyes. This paper deals with the degradation of acid red-26 (AR-26), an azo dye by hexacyanoferrate (abbreviated as HCF) (III) using iridium nanoparticles. UV-vis spectroscopy has been employed to obtain the details of the oxidative degradation of the selected dye. The effect of various operational parameters such as HCF(III) concentration, pH, initial dye concentration, catalyst and temperature was investigated systematically at the λ max , 507 nm, of the reaction mixture. Degradation kinetics follows the first order kinetic model with respect to AR-26 and Ir nano concentrations, while with respect to the HCF(III) concentration reaction it follows first order kinetics at lower concentrations, tending towards zero order at higher concentrations. Thermodynamic parameters have been calculated by studying the reaction rate at four different temperatures. The UV-vis, high performance liquid chromatography (HPLC), liquid chromatography-mass spectrometry (LC-MS) analysis of degradation products showed the formation of carboxylic acid and substituted carboxylic acids as major degradation products, which are simple and less hazardous compounds. The big advantage of the present method is the recovery and reuse of iridium nanoparticles. Moreover, turnover frequencies for each catalytic cycle have been determined, indicating the long life span of Ir nanoparticles. Thus, the finding is a novel and highly economical alternative for environmental safety against pollution by dyes, and extendable for other contaminants as well.

  1. COMPARATIVE STUDY OF THE SHEAR BOND STRENGTH OF COMPOSITE RESIN TO DENTAL ENAMEL CONDITIONED WITH PHOSPHORIC ACID OR Nd: YAG LASER

    Directory of Open Access Journals (Sweden)

    EDUARDO Carlos de Paula

    1997-01-01

    Full Text Available This study has been focused on a comparison between the shear bond strength of a composite resin attached to dental enamel surface, after a 35% phosphoric acid etching and after a Nd:YAG laser irradiation with 165.8 J/cm2 of energy density per pulse. After etching and attaching resin to these surfaces, the specimens were thermocycled and then underwent the shearing bond strength tests at a speed of 5 mm/min. The results achieved, after statistical analysis with Student's t-test, showed that the adhesion was significantly greater in the 35% phosphoric acid treated group than in the group treated with the Nd:YAG laser, thus demonstrating the need for developing new studies to reach the ideal parameters for an effective enamel surface conditioning as well as specific adhesives and composite resins when Nd:YAG laser is used

  2. Effect of alcohols on elution chromatography of trivalent actinides and lanthanides using tertiary pyridine resin with hydrochloric acid-alcohol mixed solvents.

    Science.gov (United States)

    Ikeda, Atsushi; Suzuki, Tatsuya; Aida, Masao; Fujii, Yasuhiko; Itoh, Keisuke; Mitsugashira, Toshiaki; Hara, Mitsuo; Ozawa, Masaki

    2004-07-02

    Elution chromatography with a tertiary pyridine resin has been used to separate the trivalent actinides (An3+) from the lanthanides (Ln3+) using an alcoholic hydrochloric acid solvent. Trivalent Am and Cm were separated from the Ln by employing a 1 cm(phi) x 10 cm resin column with the mixed solvent system composed of concentrated hydrochloric acid (HCl) and alcohols. The distribution coefficients (Kd) and the separation factors between An and Ln (alpha(An)(Ln)) increased as the alcohol content of the solvent mixture increased. On the other hand, the Kd and alpha(An)(Ln) decreased drastically upon the addition of water to the solvent mixture. Among the four alcohols investigated (methanol, ethanol, n-propanol and n-butanol), the ethanol-HCl mixed solvent system showed the largest Kd and alpha(An)(Ln). The mechanism of adsorption for An and Ln cations on the pyridine resin is discussed in addition to the results presented herein.

  3. Varying Conditions for Hexanoic Acid Degradation with BioTigerTM

    International Nuclear Information System (INIS)

    Foreman, Koji; Milliken, Charles; Brigmon, Robin

    2016-01-01

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

  4. Preparation of a ribonucleic acid-(polyamidoamine)-(zirconia-urea-formaldehyde resin) high-performance liquid affinity chromatographic stationary phase.

    Science.gov (United States)

    Lei, S; Yu, S; Zhao, C

    2001-07-01

    A preparative method for a high-performance liquid affinity chromatographic (HPLAC) stationary phase is described. The 3- to 5-microm nonporous composite spherical microparticles of zirconia and urea-formaldehyde (UF) resin are synthesized through the reaction of zirconyl chloride with hexamethylene tetra-amine and urea, and then it is used as the matrix of the HPLAC stationary phase of which the diameter and structure are determined by scanning electron microscopy. In a methanol medium, the polyamidoamine (PAMAM) starburst dentritic spacer arms are linked with the imido-groups on the surface of the matrix by the Michael addition reaction with methyl acrylate and the amination reaction with ethylene diamine. After repeating these steps in triplets, amine-terminated dentritic spacer arms with a generation of 3 are obtained. The topological structure of the spacer arms is examined by solid-state 13C NMR. The Br-substituted ribonucleic acid (RNA) ligand is obtained by the reaction of liquid bromine with RNA and bonded to the dendritic spacer arms of the matrix in a solution of NaOH (pH 9-11). The binding capacity of RNA is measured by UV spectrophotometry. A new type of stationary phase--RNA-(PAMAM)-(zirconia-UF resin--for HPLAC, which possesses starburst dendritic spacer arms, is synthesized and used for the separation of biological macromolecules.

  5. Purification of gamma-amino butyric acid (GABA) from fermentation of defatted rice bran extract by using ion exchange resin

    Science.gov (United States)

    Tuan Nha, Vi; Phung, Le Thi Kim; Dat, Lai Quoc

    2017-09-01

    Rice bran is one of the significant byproducts of rice processing with 10 %w/w of constitution of whole rice grain. It is rich in nutrient compounds, including glutamic acid. Thus, it could be utilized for the fermentation with Lactobateria for synthesis of GABA, a valuable bioactive for antihypertensive effects. However, the concentration and purity of GABA in fermentation broth of defatted rice bran extract is low for production of GABA drug. This research focused on the purification of GABA from the fermentation broth of defatted rice bran extract by using cation exchange resin. The results indicate that, the adsorption isotherm of GABA by Purelite C100 showed the good agreement with Freundlich model, with high adsorption capacity. The effects of pH and concentration of NaCl in eluent on the elution were also investigated. The obtained results show that, at the operating conditions of elution as follows: pH 6.5, 0.8 M of NaCl in eluent, 0.43 of bed volume; concentration of GABA in accumulative eluent, the purity and recovery yield of GABA were 743.8 ppm, 44.0% and 84.2%, respectively. Results imply that, it is feasible to apply cation exchange resin for purification of GABA from fermentation broth of defatted rice bran extract.

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

    Science.gov (United States)

    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. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. "Click" synthesis of fatty acid derivatives as fast-degrading polyanhydride precursors.

    Science.gov (United States)

    Lluch, Cristina; Lligadas, Gerard; Ronda, Joan C; Galià, Marina; Cadiz, Virginia

    2011-09-01

    Fast-degrading linear and branched polyanhydrides are obtained by melt-condensation of novel di- and tri-carboxylic acid monomers based on oleic and undecylenic acid synthesized using photoinitiated thiol-ene click chemistry. (1)H NMR spectroscopy, size exclusion chromatography, differential scanning calorimetry, thermogravimetric analysis, and FT-IR spectroscopy have been used to fully characterize these polymers. The hydrolytic degradation of these polymers was studied by means of weight loss, anhydride bond loss, and changes in molecular weight, showing fast degrading properties. Drug release studies from the synthesized polyanhydrides have also been conducted, using rhodamine B as a hydrophobic model drug, to evaluate the potential of these polymers in biomedical applications. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    International Nuclear Information System (INIS)

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

    2015-01-01

    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. (paper)

  9. Silage fermentation and ruminal degradation of stylo prepared with lactic acid bacteria and cellulase.

    Science.gov (United States)

    Li, Mao; Zhou, Hanlin; Zi, Xuejuan; Cai, Yimin

    2017-10-01

    In order to improve the silage fermentation of stylo (Stylosanthes guianensis) in tropical areas, stylo silages were prepared with commercial additives Lactobacillus plantarum Chikuso-1 (CH1), L. rhamnasus Snow Lact L (SN), Acremonium cellulase (CE) and their combination as SN+CE or CH1 + CE, and the fermentation quality, chemical composition and ruminal degradation of these silages were studied. Stylo silages treated with lactic acid bacteria (LAB) or cellulase, the pH value and NH 3 -N ⁄ total-N were significantly (P fermentation and ruminal degradation than SN+CE treatment. The results confirmed that LAB or LAB plus cellulase treatment could improve the fermentation quality, chemical composition and ruminal degradation of stylo silage. Moreover, the combined treatment with LAB and cellulase may have beneficial synergistic effects on ruminal degradation. © 2017 Japanese Society of Animal Science.

  10. Diurnal variation in degradation of phytic acid by plant phytase in the pig stomach

    NARCIS (Netherlands)

    Kemme, P.A.; Jongbloed, A.W.; Mroz, Z.; Beynen, A.C.

    1998-01-01

    The effects of plant phytase on the gastric degradation of phytic acid and digestibilities of DM and P, and their diurnal variation were evaluated in pigs from 90 to 115 kg BW fitted with simple duodenal T-cannulas. Three diets were fed to three pigs in four collection periods according to a

  11. Ecophysiology of syntrophic communities that degrade saturated and unsaturated long-chain fatty acids

    NARCIS (Netherlands)

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

    2009-01-01

    Syntrophic relationships are the key for biodegradation in methanogenic environments. We review the ecological and physiological features of syntrophic communities involved in the degradation of saturated and unsaturated long-chain fatty acids (LCFA), as well as their potential application to

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

    Czech Academy of Sciences Publication Activity Database

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

    2005-01-01

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

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

    DEFF Research Database (Denmark)

    Hawkins, C L; Davies, Michael Jonathan

    1998-01-01

    the site(s) of HOCl/ClO- attack, the intermediates formed, or the mechanism(s) of polymer degradation. In this study reaction of HOCl/ClO- with amides, sugars, polysaccharides, and hyaluronic acid has been monitored by UV-visible (220-340 nm) and EPR spectroscopy. UV-visible experiments have shown...

  14. Can heat treatment procedures of pre-hydrolyzed silane replace hydrofluoric acid in the adhesion of resin cement to feldspathic ceramic?

    Science.gov (United States)

    Cotes, Caroline; de Carvalho, Rodrigo Furtado; Kimpara, Estevão Tomomitsu; Leite, Fabíola Pessoa; Ozcan, Mutlu

    2013-12-01

    To evaluate the influence of heat treatment (HT) procedures of a pre-hydrolyzed silane on bond strength of resin cement to a feldspathic ceramic. Ceramic and composite blocks (N = 30) were divided into six groups (n = 5) and subjected to the following conditioning procedures: G1: 9.6% hydrofluoric acid (HF) for 20 s + silane (RelyX Ceramic Primer, 3M ESPE) + resin cement (Panavia F2.0, Kuraray) (control); G2: HF (20 s) + silane + heat treatment in furnace (HTF) (100°C, 2 min) + resin cement; G3: silane + HTF + resin cement; G4- HF (20 s) + silane + heat treatment with hot air (HTA) (50 ± 5°C for 1 min) + resin cement; G5: silane + HTA + resin cement; G6: silane + resin cement. The microtensile bond strength (MTBS) test was performed using a universal testing machine (1 mm/min). After debonding, the substrate and adherent surfaces were analyzed using a stereomicroscope and SEM to categorize the failure types. The data were statistically evaluated using one-way ANOVA and Tukey's test (5%). The control group (G1) showed no pre-test failures and presented significantly higher mean MTBS (16.01 ± 1.12 MPa) than did other groups (2.63 ± 1.05 to 12.55 ± 1.52 MPa) (p = 0.0001). In the groups where HF was not used, HTF (G3: 12.55 ± 1.52 MPa) showed significantly higher MTBS than did HTA (G5: 2.63 ± 1.05 MPa) (p silane either in a furnace or with the application of hot air cannot replace the use of HF gel for the adhesion of resin cement to feldspathic ceramic. Yet when mean bond strengths and incidence of pre-test failures are considered, furnace heat treatment delivered the second best results after the control group, being considerably better than hot air application.

  15. Degradation of extracellular matrix by peroxynitrite/peroxynitrous acid.

    Science.gov (United States)

    Kennett, Eleanor C; Davies, Michael J

    2008-09-01

    The extracellular matrix (ECM) provides strength and elasticity to tissues and plays a key role in regulating cell behavior; damage to this material is believed to be a major factor in many inflammatory diseases. Peroxynitrite/peroxynitrous acid, which is generated at elevated levels at sites of inflammation, is believed to play a role in ECM damage; however, the mechanisms involved are poorly understood. Here we examined the reactions of bolus peroxynitrite, and that generated in a time-dependent manner by SIN-1 decomposition, with ECM isolated from a vascular smooth muscle cell line and porcine thoracic aorta. Bolus peroxynitrite caused the release of ECM glycosaminoglycans and proteins, the formation of 3-nitroTyr, and the detection of ECM-derived radicals (by immuno-spin trapping) in a concentration-dependent manner. Release and nitration of ECM components were modulated by the local pH and bicarbonate. SIN-1 caused the release of glycosaminoglycan, but not protein, from vascular smooth muscle cell-derived ECM in a concentration-, time-, and pH-dependent manner. The data presented here suggest that peroxynitrite-mediated damage to ECM occurs via a radical-mediated pathway. These reactions may contribute to ECM damage at sites of inflammation and play a role in disease progression, including rupture of atherosclerotic lesions.

  16. Characterization of Group V Dubnium Homologs on DGA Extraction Chromatography Resin from Nitric and Hydrofluoric Acid Matrices

    Energy Technology Data Exchange (ETDEWEB)

    Despotopulos, J D; Sudowe, R

    2012-02-21

    somewhere between Nb and Pa. Much more recent studies have examined the properties of Db from HNO{sub 3}/HF matrices, and suggest Db forms complexes similar to those of Pa. Very little experimental work into the behavior of element 114 has been performed. Thermochromatography experiments of three atoms of element 114 indicate that the element 114 is at least as volatile as Hg, At, and element 112. Lead was shown to deposit on gold at temperatures about 1000 C higher than the atoms of element 114. Results indicate a substantially increased stability of element 114. No liquid phase studies of element 114 or its homologs (Pb, Sn, Ge) or pseudo-homologs (Hg, Cd) have been performed. Theoretical predictions indicate that element 114 is should have a much more stable +2 oxidation state and neutral state than Pb, which would result in element 114 being less reactive and less metallic than Pb. The relativistic effects on the 7p{sub 1/2} electrons are predicted to cause a diagonal relationship to be introduced into the periodic table. Therefore, 114{sup 2+} is expected to behave as if it were somewhere between Hg{sup 2+}, Cd{sup 2+}, and Pb{sup 2+}. In this work two commercially available extraction chromatography resins are evaluated, one for the separation of Db homologs and pseudo?homologs from each other as well as from potential interfering elements such as Group IV Rf homologs and actinides, and the other for separation of element 114 homologs. One resin, Eichrom's DGA resin, contains a N,N,N',N'-tetra-n-octyldiglycolamide extractant, which separates analytes based on both size and charge characteristics of the solvated metal species, coated on an inert support. The DGA resin was examined for Db chemical systems, and shows a high degree of selectivity for tri-, tetra-, and hexavalent metal ions in multiple acid matrices with fast kinetics. The other resin, Eichrom's Pb resin, contains a di-t-butylcyclohexano 18-crown-6 extractant with isodecanol solvent

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

    Science.gov (United States)

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

    2012-02-10

    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 methacrylamido-terminated peptide macromonomers, resulting in polymers with low polydispersity and near quantitative incorporation of peptides. Three peptide-HPMA copolymers were evaluated: (i) pHCathK(10), 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)K(10), containing the FKFL linker with oligo-(D)-lysine, and (iii) pH(D)Cath(D)K(10), containing all (D) amino acids. Cathepsin B degraded copolymers pHCathK(10) and pHCath(D)K(10) within 1 h while no degradation of pH(D)Cath(D)K(10) was observed. Polyplexes formed with pHCathK(10) copolymers show DNA release by 4 h of treatment with cathepsin B; comparatively, polyplexes formed with pHCath(D)K(10) and pH(D)Cath(D)K(10) show no DNA release within 8 h. Transfection efficiency in HeLa and NIH/3T3 cells were comparable between the copolymers but pHCathK(10) was less toxic. This work demonstrates the successful application of peptide linkers for degradable cationic polymers and DNA release. Copyright © 2011 Elsevier B.V. All rights reserved.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-11-15

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

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

    International Nuclear Information System (INIS)

    Cervantes, Francisco J.; Mancilla, Ana Rosa; Toro, E. Emilia Rios-del; Alpuche-Solis, Angel G.; Montoya-Lorenzana, Lilia

    2011-01-01

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

  20. Design of a metal primer containing a dithiooctanoate monomer and a phosphonic acid monomer for bonding of prosthetic light-curing resin composite to gold, dental precious and non-precious metal alloys.

    Science.gov (United States)

    Ikemura, Kunio; Fujii, Toshihide; Negoro, Noriyuki; Endo, Takeshi; Kadoma, Yoshinori

    2011-01-01

    The effect of metal primers on adhesion of a resin composite to dental metal alloys was investigated. Experimental primers containing a dithiooctanoate monomer [10-methacryloyloxydecyl 6,8-dithiooctanoate (10-MDDT) or 6-methacryloyloxyhexyl 6,8-dithiooctanoate (6-MHDT)] and a phosphonic acid monomer [6-methacryloyloxyhexyl phosphonoacetate (6-MHPA) or 6-methacryloyloxyhexyl 3-phosphonopropionate (6-MHPP)] were prepared. After treating Au, Au alloy, Ag alloy, Au-Ag-Pd alloy, and Ni-Cr alloy with the experimental primers, their shear bond strengths (SBSs) with a prosthetic light-curing resin composite (Solidex, Shofu Inc., Japan) were measured after 1-day storage followed by 5,000 thermal cycles. The SBSs between Solidex and the primer-treated metals which were incubated in air at 50°C for 2 months were further measured. Results showed that the SBSs [mean (SD)] of all metal adherends treated with primer DT-PA-1 (5.0 wt% 10-MDDT, 1.0 wt% 6-MHPA) ranged between 31.2 (5.2) and 34.5 (5.8) MPa. The SBSs of the primer-treated metals did not degrade after 2-month incubation at 50°C. Therefore, a combined primer application consisting of a dithiooctanoate monomer and a phosphonic acid monomer provided efficacious bonding to Au as well as precious and non-precious metal alloys.

  1. Anaerobic degradation of amino acids generated from the hydrolysis of sewage sludge.

    Science.gov (United States)

    Park, Junghoon; Park, Seyong; Kim, Moonil

    2014-01-01

    The anaerobic degradation of each amino acid that could be generated through the hydrolysis of sewage sludge was evaluated. Stickland reaction as an intermediate reaction between two kinds of amino acids was restricted in order to evaluate each amino acid. Changes in the chemical oxygen demand (COD), T-N, NH4(+)-N, biogas, and CH4 were analysed for the anaerobic digestion process. The initial nitrogen concentration of all amino acids is adjusted as 1000 mg/L. The degradation rate of the amino acids was determined based on the ammonia form of nitrogen, which is generated by the deamination of amino acids. Among all amino acids, such as alpha-alanine, beta-alanine, lysine, arginine, glycine, histidine, cysteine, methionine, and leucine, deamination rates of cysteine, leucine, and methionine were just 61.55%, 54.59%, and 46.61%, respectively, and they had low removal rates of organic matter and showed very low methane production rates of 13.55, 71.04, and 80.77 mL CH4/g CODin, respectively. Especially for cysteine, the methane content was maintained at approximately 7% during the experiment. If wastewater contains high levels of cysteine, leucine, and methionine and Stickland reaction is not prepared, these amino acids may reduce the efficiency of the anaerobic digestion.

  2. SOLVENT EFFECTS ON THE HYDRATION OF CYCLOHEXENE CATALYZED BY A STRONG ACID ION-EXCHANGE RESIN .3. EFFECT OF SULFOLANE ON THE EQUILIBRIUM CONVERSION

    NARCIS (Netherlands)

    PANNEMAN, HJ; BEENACKERS, AACM

    The liquid-phase hydration of cyclohexene, a pseudo-first-order reversible reaction catalyzed by a strong acid ion-exchange resin, was investigated in solvent mixtures of water and sulfolane. Macroporous Amberlite XE 307 was used because of its superior catalytic activity. Chemical equilibrium

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

    KAUST Repository

    Bargiela, Rafael

    2015-11-24

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

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

    Directory of Open Access Journals (Sweden)

    Rafael eBargiela

    2015-11-01

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

  5. Coordinated Regulation of Species-Specific Hydroxycinnamic Acid Degradation and Siderophore Biosynthesis Pathways in Agrobacterium fabrum

    Science.gov (United States)

    Baude, Jessica; Vial, Ludovic; Villard, Camille; Campillo, Tony; Lavire, Céline; Nesme, Xavier

    2016-01-01

    ABSTRACT The rhizosphere-inhabiting species Agrobacterium fabrum (genomospecies G8 of the Agrobacterium tumefaciens species complex) is known to degrade hydroxycinnamic acids (HCAs), especially ferulic acid and p-coumaric acid, via the novel A. fabrum HCA degradation pathway. Gene expression profiles of A. fabrum strain C58 were investigated in the presence of HCAs, using a C58 whole-genome oligoarray. Both ferulic acid and p-coumaric acid caused variations in the expression of more than 10% of the C58 genes. Genes of the A. fabrum HCA degradation pathway, together with the genes involved in iron acquisition, were among the most highly induced in the presence of HCAs. Two operons coding for the biosynthesis of a particular siderophore, as well as genes of the A. fabrum HCA degradation pathway, have been described as being specific to the species. We demonstrate here their coordinated expression, emphasizing the interdependence between the iron concentration in the growth medium and the rate at which ferulic acid is degraded by cells. The coordinated expression of these functions may be advantageous in HCA-rich but iron-starved environments in which microorganisms have to compete for both iron and carbon sources, such as in plant roots. The present results confirm that there is cooperation between the A. fabrum-specific genes, defining a particular ecological niche. IMPORTANCE We previously identified seven genomic regions in Agrobacterium fabrum that were specifically present in all of the members of this species only. Here we demonstrated that two of these regions, encoding the hydroxycinnamic acid degradation pathway and the iron acquisition pathway, were regulated in a coordinated manner. The coexpression of these functions may be advantageous in hydroxycinnamic acid-rich but iron-starved environments in which microorganisms have to compete for both iron and carbon sources, such as in plant roots. These data support the view that bacterial genomic species

  6. Complexing properties of the main organic acids used in decontamination solutions and reactions involved in their degradation or elimination

    International Nuclear Information System (INIS)

    Noel, D.; Kerrec, O.; Lantes, B.; Rosset, R.; Bayri, B.; Desbarres, J.; Jardy, A.

    1994-09-01

    This paper presents a study that, parallel with the industrial development of the decontamination chemical process, has been performed more fundamentally on the chemical properties of used products: degradation reaction during process or after decontamination and during wastes treatment. In particular, results show that the organic compounds used have no interaction with resins during radioactive wastes storage and therefore they do not present leaching risk. (authors). 8 refs., 3 figs., 4 tabs

  7. Advanced degradation of brominated epoxy resin and simultaneous transformation of glass fiber from waste printed circuit boards by improved supercritical water oxidation processes.

    Science.gov (United States)

    Liu, Kang; Zhang, Zhiyuan; Zhang, Fu-Shen

    2016-10-01

    This work investigated various supercritical water oxidation (SCWO) systems, i.e. SCWO1 (only water), SCWO2 (water+H2O2) and SCWO3 (water+H2O2/NaOH), for waste printed circuit boards (PCBs) detoxification and recycling. Response surface methodology (RSM) was applied to optimize the operating conditions of the optimal SCWO3 systems. The optimal reaction conditions for debromination were found to be the NaOH of 0.21g, the H2O2 volume of 9.04mL, the time of 39.7min, maximum debromination efficiency of 95.14%. Variance analysis indicated that the factors influencing debromination efficiency was in the sequence of NaOH>H2O2>time. Mechanism studies indicated that the dissociated ions from NaOH in supercritical water promoted the debromination of brominated epoxy resins (BERs) through an elimination reaction and nucleophilic substitution. HO2, produced by H2O2 could induce the oxidation of phenol ring to open (intermediates of BERs), which were thoroughly degraded to form hydrocarbons, CO2, H2O and NaBr. In addition, the alkali-silica reaction between OH(-) and SiO2 induced the phase transformation of glass fibers, which were simultaneously converted into anorthite and albite. Waste PCBs in H2O2/NaOH improved SCWO system were fully degraded into useful products and simultaneously transformed into functional materials. These findings are helpful for efficient recycling of waste PCBs. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Properties of the Carboxylate ion exchange resins

    International Nuclear Information System (INIS)

    Allard, Bert; Dario, Maarten; Boren, Hans; Torstenfelt, Boerje; Puigdomenech, Ignasi; Johansson, Claes

    2002-09-01

    Weakly acidic, carboxylic resin has been selected, together with strong base anion resins, for water purification at the Forsmark 1 and 2 reactors. For the strong (but not the weak) ion exchange resin the Nuclear Power Inspectorate has given permission to dispose the spent resins in the SFR 1 (the Final Repository for Radioactive Operational Waste). This report gives a review of the carboxylic resins and comes to the conclusion that the resins are very stable and that there should not exist any risks for increased leaching of radionuclides from SFR 1 if these resins are disposed (compared to the strong resins)

  9. Degradation characteristics of 2,4-dichlorophenoxyacetic acid in electro-biological system

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, JingLi, E-mail: jinglizhangczp@126.com [Tianjin Key Laboratory of Aquatic Science and Technology, Tianjin Institute of Urban Construction, Tianjin 300384 (China); Cao, ZhanPing; Zhang, HongWei [School of Environmental and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300387 (China); Zhao, LianMei [Tianjin Key Laboratory of Aquatic Science and Technology, Tianjin Institute of Urban Construction, Tianjin 300384 (China); Sun, XuDong; Mei, Feng [School of Environmental and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300387 (China)

    2013-11-15

    Highlights: • The 2,4-D reductive degradation was studied in an electro-biological system. • The electric auxiliary accelerates 2,4-D microbial degradation. • A electron transfer is achieved between the electrode, bacteria and the pollutants. • The paper provides a promising way for the degradation of persistent organics. -- Abstract: The reductive degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) was studied in an electro-biological system, a biological system and an electric catalytic system, respectively. Electrochemical characteristics were monitored by cyclic voltammetry and the intermediate products of 2,4-D degradation were determined by high speed liquid chromatography (HPLC). The results showed that all 2,4-D degradations in the three systems conformed to the kinetics characteristics of one-order reaction, and the degradation kinetics constants were 28.74 × 10{sup −2} h{sup −1}, 19.73 × 10{sup −2} h{sup −1} and 3.54 × 10{sup −2} h{sup −1}, respectively. The kinetics constant in the electro-biological system was higher than the sum in the other two systems by 19%. The electrochemical assistance provided the electrons and accelerated the electron transfer rate in the microbial degradation of 2,4-D. The degradation resulted from the microbial reduction strengthened by the electrochemical assistance. The electron transfer existed between the electrode, cytochrome, NAD and the pollutants. A long-range electron transfer process could be achieved on the multi-phase interfaces between the electrode, bacteria and the pollutants.

  10. Degradation characteristics of 2,4-dichlorophenoxyacetic acid in electro-biological system

    International Nuclear Information System (INIS)

    Zhang, JingLi; Cao, ZhanPing; Zhang, HongWei; Zhao, LianMei; Sun, XuDong; Mei, Feng

    2013-01-01

    Highlights: • The 2,4-D reductive degradation was studied in an electro-biological system. • The electric auxiliary accelerates 2,4-D microbial degradation. • A electron transfer is achieved between the electrode, bacteria and the pollutants. • The paper provides a promising way for the degradation of persistent organics. -- Abstract: The reductive degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) was studied in an electro-biological system, a biological system and an electric catalytic system, respectively. Electrochemical characteristics were monitored by cyclic voltammetry and the intermediate products of 2,4-D degradation were determined by high speed liquid chromatography (HPLC). The results showed that all 2,4-D degradations in the three systems conformed to the kinetics characteristics of one-order reaction, and the degradation kinetics constants were 28.74 × 10 −2 h −1 , 19.73 × 10 −2 h −1 and 3.54 × 10 −2 h −1 , respectively. The kinetics constant in the electro-biological system was higher than the sum in the other two systems by 19%. The electrochemical assistance provided the electrons and accelerated the electron transfer rate in the microbial degradation of 2,4-D. The degradation resulted from the microbial reduction strengthened by the electrochemical assistance. The electron transfer existed between the electrode, cytochrome, NAD and the pollutants. A long-range electron transfer process could be achieved on the multi-phase interfaces between the electrode, bacteria and the pollutants

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-07-01

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

  12. Unravelling the gallic acid degradation pathway in bacteria: the gal cluster from Pseudomonas putida.

    Science.gov (United States)

    Nogales, Juan; Canales, Angeles; Jiménez-Barbero, Jesús; Serra, Beatriz; Pingarrón, José Manuel; García, José Luis; Díaz, Eduardo

    2011-01-01

    Gallic acid (3,4,5-trihydroxybenzoic acid, GA) is widely distributed in nature, being a major phenolic pollutant and a commonly used antioxidant and building-block for drug development. We have characterized the first complete cluster (gal genes) responsible for growth in GA in a derivative of the model bacterium Pseudomonas putida KT2440. GalT mediates specific GA uptake and chemotaxis, and highlights the critical role of GA transport in bacterial adaptation to GA consumption. The proposed GA degradation via the central intermediate 4-oxalomesaconic acid (OMA) was revisited and all enzymes involved have been identified. Thus, GalD is the prototype of a new subfamily of isomerases that catalyses a biochemical step that remained unknown, i.e. the tautomerization of the OMAketo generated by the GalA dioxygenase to OMAenol. GalB is the founding member of a new family of zinc-containing hydratases that converts OMAenol into 4-carboxy-4-hydroxy-2-oxoadipic acid (CHA). galC encodes the aldolase catalysing CHA cleavage to pyruvic and oxaloacetic acids. The presence of homologous gal clusters outside the Pseudomonas genus sheds light on the evolution and ecology of the gal genes in GA degraders. The gal genes were used for expanding the metabolic abilities of heterologous hosts towards GA degradation, and for engineering a GA cellular biosensor. © 2010 Blackwell Publishing Ltd.

  13. Catalytic Upgrading of bio-oil using 1-octene and 1-butanol over sulfonic acid resin catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhijun; Wang, Qingwen; Tripathi, Prabhat; Pittman, Charles U.

    2011-02-04

    Raw bio-oil from fast pyrolysis of biomass must be refined before it can be used as a transporation fuel, a petroleum refinery feed or for many other fuel uses. Raw bio-oil was upgraded with the neat model olefin, 1-octene, and with 1-octene/1-butanol mixtures over sulfonic acid resin catalysts frin 80 to 150 degrees celisus in order to simultaneously lower water content and acidity and to increase hydrophobicity and heating value. Phase separation and coke formation were key factors limiting the reaction rate during upgrading with neat 1-octene although octanols were formed by 1-octene hydration along with small amounts of octyl acetates and ethers. GC-MS analysis confirmed that olefin hydration, carboxylic acid esterification, acetal formation from aldehydes and ketones and O- and C-alkylations of phenolic compounds occurred simultaneously during upgrading with 1-octene/1-butanol mixtures. Addition of 1-butanol increased olefin conversion dramatically be reducing mass transfer restraints and serving as a cosolvent or emulsifying agent. It also reacted with carboxylic acids and aldehydes/ketones to form esters, and acetals, respectively, while also serving to stabilize bio-oil during heating. 1-Butanol addition also protected the catalysts, increasing catalyst lifetime and reducing or eliminationg coking. Upgrading sharply increased ester content and decreased the amounts of levoglucosan, polyhydric alcohols and organic acids. Upgrading lowered acidity (pH value rise from 2.5 to >3.0), removed the uppleasant ordor and increased hydrocarbon solubility. Water content decreased from 37.2% to < 7.5% dramatically and calorific value increased from 12.6 MJ kg to about 30.0 MJ kg.

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

    Directory of Open Access Journals (Sweden)

    Ufana Riaz

    2014-01-01

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

  15. Rumen degradability and ileal digestibility of proteins and amino acids of feedstuffs for cows

    Directory of Open Access Journals (Sweden)

    Iveta Maskaľová

    2014-01-01

    Full Text Available Knowledge of the profile of amino acids of the rumen-undegradable protein can help in the formulation of diets to provide amino acids that complement microbial protein as well as supply amino acids, which are most limiting for milk production. Three non-lactating cows fitted with rumen cannulas were used to determine the effect of in situ rumen degradation on crude protein and amino acid profile of rumen-undegraded protein of feedstuffs. The obtained values of rumen degradability of crude protein with significant difference (P in vitro modified 3-step method was used to determine intestinal digestibility. Intestinal digestibility of undegraded protein varied from 54.5 ± 1.4% in raw soybean to 95.2 ± 1.0% in corn gluten feed. The absorbable amino acid profile of rumen-undegraded protein for each feedstuff was compared with profiles of the original feedstuff and the rumen-exposed undegraded protein. Absorbable lysine (9.3 ± 1.1 g/kg of crude protein was higher in products of soybean and sunflower cake. Corn gluten feed and meal supplied more absorbable methionine (3.6 ± 0.6 g/kg of crude protein. This study showed that the digestibility factor of crude protein and amino acid based on in situ and in vitro methods for thermal treatment of protein feeds can be used in models to optimize the amino acid nutrition of dairy cows and expand knowledge about rumen degradability and ileal digestibility of amino acids in feedstuffs.

  16. Degradation of amino acids to short-chain fatty acids in humans. An in vitro study

    DEFF Research Database (Denmark)

    Rasmussen, H S; Holtug, K; Mortensen, P B

    1988-01-01

    Short-chain fatty acids (SCFA) originate mainly in the colon through bacterial fermentation of polysaccharides. To test the hypothesis that SCFA may originate from polypeptides as well, the production of these acids from albumin and specific amino acids was examined in a faecal incubation system....... Albumin was converted to all C2-C5-fatty acids, whereas amino acids generally were converted to specific SCFA, most often through the combination of a deamination and decarboxylation of the amino acids, although more complex processes also took place. This study indicates that a part of the intestinal...

  17. [Analysis of degradation failure of poly L-lactic acid fixators used in meniscus tears].

    Science.gov (United States)

    Ceyhan, Taşkin; Aşik, Mehmet; Atalar, Ata Can; Apohan, Nilhan Kayaman

    2008-01-01

    Biodegradable poly L-lactic acid (PLLA) fixators used in the repair of meniscal tears may cause adverse reactions inside the knee due to delayed degradation. This study was designed to determine the reasons for late degradation of PLLA fixators. Three unused and three used meniscal PLLA fixators (BioStinger) were analyzed. The latter were removed from three patients due to persisting symptoms within six months after knee arthroscopy. Fourier transform infrared (FTIR) spectroscopy was performed and external and internal surfaces of the samples were examined by scanning electron microscopy (SEM) and X-ray fluoroscopy (XRF). Chemical structural analyses of two samples (one from each group) were made by 1H-nuclear magnetic resonance (1H-NMR) spectroscopy. Degradation times of two samples (one from each group) by oxidative hydrolysis in hydrogen peroxide solution were recorded. Chemical structure of used and unused fixators did not differ in FTIR analysis. With increasing temperatures, unused and used fixators showed degradation with and without melt flow, respectively. In SEM analysis, inner sections of unused fixators were homogeneous, whereas those of the used ones exhibited crystals which were found to be sodium and potassium chloride salts in XRF analysis. The 1H-NMR spectrum of used and unused samples showed the normal pattern of lactic acid polymer. The unused and used fixators degraded in hydrogen peroxide solution in 10 days and 30 days, respectively. Both fixators had the same chemical structure in FTIR and NMR analyses. Formation of salt crystals seemed to be the most important cause of degradation failure, while changes in the physical properties of fixators were thought to be associated with delayed degradation.

  18. Consequences of enamel preparation with sodium hypochlorite, polyacrylic and phosphoric acids for the bonding of brackets with resin-modified glass ionomer cements

    OpenAIRE

    Trindade, Alessandra Marques; Pereira, Tatiana Bahia Junqueira; Smith Neto, Perrin; Horta, Martinho Campolina Rebello; Pithon, Matheus Melo; Akaki, Emílio; Oliveira, Dauro Douglas

    2013-01-01

    The aim of this study was to evaluate the effects of deproteinization with 5.25% sodium hypochlorite (NaOCl) prior to enamel conditioning with 10% polyacrylic acid (PAA) and 35% phosphoric acid (PA) on the bond strength (BS) of brackets bonded with resin-modified glass ionomer cement (RMGIC). One hundred human premolars extracted for orthodontic reasons were divided into 5 groups (n = 20 in each group): G1 (control), enamel conditioning with PA, application of adhesive and bonding of brackets...

  19. Effect Of Sodium Hypochlorite And Peracetic Acid On The Surface Roughness Of Acrylic Resin Polymerized By Heated Water For Short And Long Cycles.

    OpenAIRE

    Sczepanski, Felipe; Sczepanski, Claudia Roberta Brunnquell; Berger, Sandrine Bittencourt; Consani, Rafael Leonardo Xediek; Gonini-Júnior, Alcides; Guiraldo, Ricardo Danil

    2015-01-01

    Objective: To evaluate the surface roughness of acrylic resin submitted to chemical disinfection via 1% sodium hypochlorite (NaClO) or 1% peracetic acid (C2H4O3). Materials and Methods: The disc-shaped resin specimens (30 mm diameter ×4 mm height) were polymerized by heated water using two cycles (short cycle: 1 h at 74°C and 30 min at 100°C; conventional long cycle: 9 h at 74°C). The release of substances by these specimens in water solution was also quantified. Specimens were fabricated, di...

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

    International Nuclear Information System (INIS)

    Chu, C.C.; Campbell, N.D.

    1982-01-01

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

  1. Degradation characteristics of 2,4-dichlorophenoxyacetic acid in electro-biological system.

    Science.gov (United States)

    Zhang, Jingli; Cao, Zhanping; Zhang, Hongwei; Zhao, Lianmei; Sun, Xudong; Mei, Feng

    2013-11-15

    The reductive degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) was studied in an electro-biological system, a biological system and an electric catalytic system, respectively. Electrochemical characteristics were monitored by cyclic voltammetry and the intermediate products of 2,4-D degradation were determined by high speed liquid chromatography (HPLC). The results showed that all 2,4-D degradations in the three systems conformed to the kinetics characteristics of one-order reaction, and the degradation kinetics constants were 28.74 × 10(-2) h(-1), 19.73 × 10(-2) h(-1) and 3.54 × 10(-2) h(-1), respectively. The kinetics constant in the electro-biological system was higher than the sum in the other two systems by 19%. The electrochemical assistance provided the electrons and accelerated the electron transfer rate in the microbial degradation of 2,4-D. The degradation resulted from the microbial reduction strengthened by the electrochemical assistance. The electron transfer existed between the electrode, cytochrome, NAD and the pollutants. A long-range electron transfer process could be achieved on the multi-phase interfaces between the electrode, bacteria and the pollutants. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Degradation and contamination of perfluorinated sulfonic acid membrane due to swelling-dehydration cycles

    DEFF Research Database (Denmark)

    Andersen, Shuang Ma; Morgen, Per; Skou, Eivind Morten

    Formation of sulfonic anhydride S-O-S (from the condensation of sulfonic acids) was known one of the important degradation mechanisms [i] for Nafion membrane under hydrothermal aging condition, which is especially critical for hydrogen fuel cells. Similar mechanism would also have be desirable...... to the membrane degradation in direct methanol fuel cells (DMFCs), where liquid water has direct contact with the electrolyte. An ex-situ experiment was established with swelling-dehydration cycles on the membrane. However, formation of sulfonic anhydride was not detected during the entire treatment; instead...

  3. Enantiomeric fractioning, degradation and metabolite formation of Mecoprop in subsoils with a phenoxy acid contamination history

    DEFF Research Database (Denmark)

    Frkova, Zuzana; Johansen, Anders; Karlson, Ulrich G.

    2015-01-01

    As persistence and toxicity of the enantiomers of chiral pesticides are different a more comprehensive understanding of the fate of enantiomers of agrochemicals in the environment is necessary. Subsoils sampled vertically (2.5-6 m) at a site with a history of phenoxy acid contamination were used...... for their ability to degrade mecoprop under natural and amended conditions. Degradation of mecoprop was studied at elevated and environmentally relevant mecoprop concentrations as affected by nitrate and glucose at nitrate-reducing conditions and at a presence of oxygen (mimicking purging the soil with air. Results...

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

    DEFF Research Database (Denmark)

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

    2008-01-01

    in enrichment cultures degrading phthalic acid esters under methanogenic conditions. A selection pressure was applied by adding DBP at 10 and 200 mg L(-1) in semi-continuous anaerobic reactors. The microbial dynamics were monitored using single strand conformation polymorphism (SSCP). While only limited abiotic...... losses were observed in the sterile controls (20-22%), substantial DBP biodegradation was found in the enrichment cultures (90-99%). In addition, significant population changes were observed. The dominant bacterial species in the DBP-degrading cultures was affiliated to Soehngenia saccharolytica...

  5. Influence of humic acid addition on the degradation of pharmaceuticals by biofilms in effluent wastewater

    DEFF Research Database (Denmark)

    Tang, Kai; Escola Casas, Monica; Ooi, Gordon Tze Hoong

    2017-01-01

    in relation to the biodegradation of pharmaceuticals by suspended biofilm carriers adapted to polishing effluent water from a tertiary sewage treatment plant. Twelve out of 22 investigated pharmaceuticals were significantly biodegradable. The biodegradation rate constants of ten of those compounds were......The degradation of organic micropollutants in wastewater treatment is suspected to depend on co-degradation i.e. be dependent on concentrations of substrate. This complicates predicting and modelling their fate. The effect of humic acid, as a model for complex organic substrate, was investigated...

  6. Phytate degrading activities of lactic acid bacteria isolated from traditional fermented food

    Science.gov (United States)

    Damayanti, Ema; Ratisiwi, Febiyani Ndaru; Istiqomah, Lusty; Sembiring, Langkah; Febrisiantosa, Andi

    2017-03-01

    The objective of this study was to determine the potential of LAB with phytate degrading activity from fermented traditional food grain-based and legume-based. Lactic acid bacteria were isolated from different sources of traditional fermented food from Gunungkidul Yogyakarta Indonesia such as gembus tempeh (tofu waste), soybean tempeh, lamtoro tempeh (Leucaena bean) and kara tempeh. Isolation of LAB was performed using Total Plate Count (TPC) on de Man Rogosa Sharpe Agar (MRSA) medium supplemented with CaCO3. They were screened for their ability to degrade myo-inositol hexaphosphate or IP6 by using qualitative streak platemethod with modified de Man Rogosa-MorpholinoPropanesulfonic Acid Sharpe (MRS-MOPS) medium contained sodium salt of phytic acid as substrate and cobalt chloride staining (plate assay) method. The selected isolates were further assayed for phytase activities using quantitative method with spectrophotometer and the two selected isolates growth were optimized. Furthermore, thhe isolates that shown the highest phytase activity was characterized and identified using API 50 CH kitand 16S rRNA gene sequencing. The results showed that there were 18 LAB isolates obtained from samplesand 13 isolates were able to degrade sodium phytate based on qualitative screening. According to quantitative assay, the highest phytate degrading activities were found in TG-2(23.562 U/mL) and TG-1 (19.641 U/mL) isolated from gembus tempeh. The phytate activity of TG-2 was optimum at 37 °C with agitation, while the phytate activity of TG-1 was optimum at 45 °C without agitation. Characterization and identification of TG-2 isolate with the highest phytate degrading activity using API 50 CH and 16S rRNA showed that TG-2had homology with Lactobacillus fermentum. It could be concluded that LAB from from fermented traditional food grain-based and legume-based produced the extracellular phytase. Keywords: lactic acid bacteria, tempeh, phytatedegrading activity

  7. In vitro degradation of biodegradable polylactic acid/magnesium composites: Relevance of Mg particle shape.

    Science.gov (United States)

    Cifuentes, S C; Gavilán, R; Lieblich, M; Benavente, R; González-Carrasco, J L

    2016-03-01

    Absorbable medical devices must be developed in order to have an appropriate degradation rate in agreement with the healing rate of bone in the implantation site. In this work, biodegradable composites formed by a polylactic acid matrix reinforced with 10%wt. magnesium microparticles were processed and their in vitro degradation investigated during 28 days. A joint analysis of the amount of H2 released, the changes in pH in buffered (PBS) and non-buffered media (distilled water), the variations in mass, microstructure and the mechanical performance of the specimens was developed. The main aim was to elucidate the relevance of Mg particles shape on tailoring the degradation kinetics of these novel composites. The results show that the shape of the Mg reinforcing particles plays a crucial role in the degradation rate of PLA/Mg composites, with spherical particles promoting a lower degradation rate than irregular particles. This fact is only partially due to the smaller surface area to volume ratio of the spherical particles. Irregular particles promote a faster formation of cracks and, therefore, an increasingly faster degradation of the polymeric matrix. In every case, the amount of H2 released by the composites was well below that released by monolithic Mg. The pH of PBS during degradation remained always within 7.2 and 7.4. PLA/Mg reinforced with spherical particles retains more than 90% of its mechanical properties after 7 days of immersion and more than 60% after 28 days. The increasing demand for temporary orthopaedic implants is the driving force to seek new strategies to decrease costs and simultaneously improve patients comfort as well as simplify surgical procedures. Resorbable medical devices must be developed in order to have an appropriate degradation rate in agreement with the healing rate of bone. We are presenting for the first time results of the degradation kinetics of a new material based on polylactic acid reinforced with 10%wt. Mg microparticles

  8. Effect of experimental acid/base conditioner on microtensile bond strength of 4-META/MMA-TBB resin to dentin after long-term water immersion.

    Science.gov (United States)

    Soeno, Kohyoh; Taira, Yohsuke; Ito, Shuichi

    2012-01-01

    An experimental conditioner (Exp), which was an aqueous solution of 10% ascorbic acid and 5% ferric chloride, was prepared in this study. This study evaluated the effect of Exp on the microtensile bond strength between a self-curing resin and dentin after long-term water immersion. Flat human dentin surfaces were sequentially pretreated with 40% phosphoric acid, 10% sodium hypochlorite, and Exp. Surface pretreatment with an aqueous solution of 10% citric and 3% ferric chloride (10-3) was used as a control. Composite resin rods were bonded to pretreated dentin surfaces using 4-META/MMA-TBB resin. Microtensile bond strengths were evaluated after water immersion at 24 h, 12 months, 24 months, and 36 months. At each immersion period, the bond strength of Exp was significantly higher than that of 10-3. After 36 months, Exp showed no significant decrease in microtensile bond strength, but 10-3 showed significant reductions. Pretreatment with experimental acid/base conditioner markedly improved the bonding durability of 4-META/MMA-TBB resin to human dentin when compared against the conventional 10-3 treatment.

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

    Directory of Open Access Journals (Sweden)

    Signe eAdamberg

    2014-12-01

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

  10. The role of nanoparticulate agglomerates in TiO{sub 2} photocatalysis: degradation of oxalic acid

    Energy Technology Data Exchange (ETDEWEB)

    Ivanova, Irina [Leibniz Universitaet Hannover, Institut fuer Technische Chemie (Germany); Mendive, Cecilia B., E-mail: cbmendive@mdp.edu.ar [Universidad Nacional de Mar del Plata, Facultad de Ciencias Exactas y Naturales, Departamento de Química (Argentina); Bahnemann, Detlef [Leibniz Universitaet Hannover, Institut fuer Technische Chemie (Germany)

    2016-07-15

    The simultaneous bimodal study of the photocatalytic oxalic acid degradation by aqueous TiO{sub 2} suspensions revealed that particular systems possess the capacity to protect a certain amount of oxalic acid from oxidation, thus hindering, to some extent, the photocatalytic reaction. While measurements of the oxalic acid concentration in the bulk liquid phase indicated full photocatalytic degradation; in situ pH-stat measurements allowed the quantification of the amount of oxalic acid remaining in the part of the nanoparticulate agglomerates where light could apparently not access. An explanation for this phenomenon takes into account the possibility of the formation of TiO{sub 2} agglomerates in which these molecules are hidden from the effect of the light, thus being protected from photocatalytic degradation. Studies of different TiO{sub 2} materials with different particle sizes allowed a deeper exploration of this phenomenon. In addition, because this property of encapsulating pollutant molecules by photocatalytic systems is found to be a reversible phenomenon, P25 appears to be more convenient and advantageous as compared to the use of large surface area photocatalysts.Graphical AbstractFig.: Deaggregation of TiO{sub 2} particle agglomerates upon UV illumination.

  11. Preparation and characterization of anion exchange resin decorated with magnetite nanoparticles for removal of p-toluic acid from aqueous solution

    Science.gov (United States)

    Davarpanah, Morteza; Ahmadpour, Ali; Rohani Bastami, Tahereh

    2015-02-01

    Polystyrene resin was covalently functionalized with diethanolamine and then decorated with magnetite nanoparticles by a novel and simple co-precipitation method using iron(II) sulfate as precursor. The products were characterized by Fourier transform infrared spectroscopy, elemental analysis, X-ray diffraction, Mössbauer spectroscopy, field-emission scanning electron microscopy and vibrating sample magnetometer. Adsorption of p-toluic acid (p-TA) onto magnetite-decorated polystyrene (MAG-PS) was studied and compared with that of diethanolamine-functionalized polystyrene and a commercial anion exchange resin. Results showed that the magnetite nanoparticles with an average size of 20.4 nm were successfully formed on the surface of polystyrene resin, and MAG-PS was exhibited high affinity for the removal of p-TA.

  12. Biocatalytic Synthesis of Epoxy Resins from Fatty Acids as a Versatile Route for the Formation of Polymer Thermosets with Tunable Properties.

    Science.gov (United States)

    Torron, Susana; Semlitsch, Stefan; Martinelle, Mats; Johansson, Mats

    2016-12-12

    The work herein presented describes the synthesis and polymerization of series of bio-based epoxy resins prepared through lipase catalyzed transesterification. The epoxy-functional polyester resins with various architectures (linear, tri-branched, and tetra-branched) were synthesized through condensation of fatty acids derived from epoxidized soybean oil and linseed oil with three different hydroxyl cores under bulk conditions. The selectivity of the lipases toward esterification/transesterification reactions allowed the formation of macromers with up to 12 epoxides in the backbone. The high degree of functionality of the resins resulted in polymer thermosets with T g values ranging from -25 to over 100 °C prepared through cationic polymerization. The determining parameters of the synthesis and the mechanism for the formation of the species were determined through kinetic studies by 1 H NMR, SEC, and molecular modeling studies. The correlation between macromer structure and thermoset properties was studied through real-time FTIR measurements, DSC, and DMA.

  13. Photooxidation of dicarboxylic acids—Part I: Effects of inorganic ions on degradation of azelaic acid

    Science.gov (United States)

    Yang, Liming; Ray, Madhumita B.; Yu, Liya E.

    In this paper, the first of a two-part series, effects of chloride, sulfate, and nitrate ions and pH on photooxidation of azelaic acid were investigated in an aqueous system. Nitrate ions play the major role in accelerating photooxidation of azelaic acid by increasing rad OH concentration, while chloride ions consume rad OH concentration and retard photooxidation rates. In inorganic mixtures, a nitrate-to-chloride molar ratio of >1.5 accelerated photooxidation of azelaic acid indicating the dominant role of nitrate. Substantial inhibition effects of chloride on photooxidation of azelaic acid were demonstrated at a nitrate-to-chloride molar ratio azelaic acid as photolysis of nitrate would significantly consume H +, retarding reaction of HOCl - with H +, and consequently decreasing rad OH-chloride reaction. pH affects photooxidation of C 2-C 9 dicarboxylic acids (DCAs) in two ways: C 2-C 4 dicarboxylates exhibit substantially higher degradation rates than their parent DCAs, while C 5-C 9 dicarboxylates demonstrate degradation rates similar to their parent DCAs.

  14. Comparison of the hydrolytic degradation and deformation properties of a PLLA-lauric acid based family of biomaterials.

    Science.gov (United States)

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

    2006-02-01

    Addition of lauric acid to PLLA results in a significantly increased rate of hydrolytic degradation, with the time-to-loss of tensile strength directly related to the concentration of lauric acid. In this study, the hydrolytic degradation profiles of four materials were studied: amorphous PLLA, amorphous PLLA containing 1.8 wt % lauric acid, amorphous PLLA containing 4.5 wt % lauric acid, and pre-crystallized PLLA containing 1.8 wt % lauric acid. Hydrolytic degradation was monitored through mass profiles, molecular weight profiles, crystallinity and the development of mechanical properties and deformation mechanisms (through simultaneous small-angle X-ray scattering and tensile testing), and a "phase diagram" of properties suggested. The key factor in determining the development of properties was found to be the time at which crystallization occurred in relation to the loss of molecular weight, with the two factors most affecting this being the lauric acid content and the pre-degradation annealing treatment.

  15. The impact of hydrofluoric acid etching followed by unfilled resin on the biaxial strength of a glass-ceramic.

    Science.gov (United States)

    Posritong, Sumana; Borges, Alexandre Luiz Souto; Chu, Tien-Min Gabriel; Eckert, George J; Bottino, Marco A; Bottino, Marco C

    2013-11-01

    To evaluate the null hypotheses that hydrofluoric (HF) acid etching time would neither decrease the biaxial flexural strength of a glass-based veneering ceramic nor enhance it after silane and unfilled resin (UR) applications. Disc-shaped IPS e.max ZirPress specimens were allocated into 12 groups: G1-control (no-etching), G2-30 s, G3-60 s, G4-90 s, G5-120 s, G6-60 s+60 s. Groups (G7-G12) were treated in the same fashion as G1-G6, but followed by silane and UR applications. Surface morphology and roughness (Ra and Rq) of the ceramics were assessed by means of scanning electron microscopy (SEM) and profilometry, respectively. Flexural strength was determined by biaxial testing. Data were analyzed by two-way ANOVA and the Sidak test (α=0.05). Weibull statistics were estimated and finite element analysis (FEA) was carried out to verify the stress concentration end areas of fracture. The interaction (etching time vs. surface treatment) was significant for Ra (p=0.008) and Rq (0.0075). Resin-treated groups presented significantly lower Ra and Rq than non-treated groups, except for the 60s group (pceramic microstructure and that the UR was able to penetrate into the irregularities. A significant effect of etching time (p=0.029) on flexural strength was seen. G7-G12 presented higher strength than G1-G6 (pceramic flexural strength. Moreover, the flexural strength could be enhanced after UR treatment. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  16. Degradation and miscibility of poly(DL-lactic acid)/poly(glycolic acid ...

    Indian Academy of Sciences (India)

    Previous research reveals that blending PGA with PLA might be effective in decreasing the degradation rate of. PGA (You et al 2005). However, our study revealed that. PDLLA and PGA were not very compatible. To remedy this, we selected PDLGA as the compatibilizer. In this study,. PDLGA/PDLLA/PGA composite films ...

  17. Oxalate-Degrading Enzyme Recombined Lactic Acid Bacteria Strains Reduce Hyperoxaluria.

    Science.gov (United States)

    Zhao, Chenming; Yang, Huan; Zhu, Xiaojing; Li, Yang; Wang, Ning; Han, Shanfu; Xu, Hua; Chen, Zhiqiang; Ye, Zhangqun

    2017-12-02

    To develop recombinant lactic acid bacteria (LAB) strains that express oxalate-degrading enzymes through biotechnology-based approach for the treatment of hyperoxaluria by oral administration. The coding gene of oxalate decarboxylase (ODC) and oxalate oxidase (OxO) was transformed into Lactococcus lactis MG1363. The oxalate degradation ability in vitro was evaluated in media with high concentration of oxalate. Hyperoxaluria rat models through high oxalate diet were given recombinant LAB through oral administration. Twenty-four-hour urinary oxalate was measured, and kidney stone formation was investigated. LAB recombined with the coding gene of ODC could effectively decrease the amount of oxalate in the media and in the urine of rats. Moreover, the formation of calcium oxalate crystals in kidneys was also inhibited. The acid-induced promoter p170 significantly enhanced the reduction of hyperoxaluria. However, recombinant LAB expressing heterologous OxO showed less efficiency in oxalate degradation even in the presence of p170. LAB expressing ODC is more efficient in degradation of oxalate in vitro and in vivo than that expressing OxO. This present study provided novel recombinant probiotic strains as a potential treatment tool against oxalosis. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Chemical composition and ruminal degradation kinetics of crude protein and amino acids, and intestinal digestibility of amino acids from tropical forages

    Directory of Open Access Journals (Sweden)

    Lidia Ferreira Miranda

    2012-03-01

    Full Text Available The objective of this research was to determine the chemical composition and ruminal degradation of the crude protein (CP, total and individual amino acids of leaves from tropical forages: perennial soybean (Neonotonia wightii, cassava (Manihot esculenta, leucaena (Leucaena leucocephala and ramie (Boehmeria nivea, and to estimate the intestinal digestibility of the rumen undegradable protein (RUDP and individual amino acids of leaves from the tropical forages above cited, but including pigeon pea (Cajanus cajan. Three nonlactating Holstein cows were used to determine the in situ ruminal degradability of protein and amino acids from leaves (6, 18 and 48 hours of ruminal incubation. For determination of the intestinal digestibility of RUDP, the residue from ruminal incubation of the materials was used for 18 hours. A larger concentration of total amino acids for ramie and smaller for perennial soybean were observed; however, they were very similar in leucaena and cassava. Leucine was the essential amino acid of greater concentration, with the exception of cassava, which exhibited a leucine concentration 40.45% smaller. Ramie showed 14.35 and 22.31% more lysine and methionine, respectively. The intestinal digestibility of RUDP varied from 23.56; 47.87; 23.48; 25.69 and 10.86% for leucaena, perennial soybean, cassava, ramie and pigeon pea, respectively. The individual amino acids of tropical forage disappeared in different extensions in the rumen. For the correct evaluation of those forages, one should consider their composition of amino acids, degradations and intestinal digestibility, once the amino acid composition of the forage does not reflect the amino acid profiles that arrived in the small intestine. Differences between the degradation curves of CP and amino acids indicate that degradation of amino acids cannot be estimated through the degradation curve of CP, and that amino acids are not degraded in a similar degradation profile.

  19. Degradation of L-Ascorbic Acid in the Amorphous Solid State.

    Science.gov (United States)

    Sanchez, Juan O; Ismail, Yahya; Christina, Belinda; Mauer, Lisa J

    2018-03-01

    Ascorbic acid degradation in amorphous solid dispersions was compared to its degradation in the crystalline state. Physical blends and lyophiles of ascorbic acid and polymers (pectins and polyvinylpyrrolidone [PVP]) were prepared initially at 50:50 (w/w), with further studies using the polymer that best inhibited ascorbic acid crystallization in the lyophiles in 14 vitamin : PVP ratios. Samples were stored in controlled environments (25 to 60 °C, 0% to 23% RH) for 1 mo and analyzed periodically to track the physical appearance, change in moisture content, physical state (powder x-ray diffraction and polarized light microscopy), and vitamin loss (high performance liquid chromatography) over time. The glass transition temperatures of select samples were determined using differential scanning calorimetry, and moisture sorption profiles were generated. Ascorbic acid in the amorphous form, even in the glassy amorphous state, was more labile than in the crystalline form in some formulations at the highest storage temperature. Lyophiles stored at 25 and 40 °C and those in which ascorbic acid had crystallized at 60 °C (≥70% ascorbic acid : PVP) had no significant difference in vitamin loss (P > 0.05) relative to physical blend controls, and the length of storage had little effect. At 60 °C, amorphous ascorbic acid lyophiles (≤60% ascorbic acid : PVP) lost significantly more vitamin (P degradation also significantly increased (P < 0.05) at lower proportions of ascorbic acid, a scenario likely encountered in foods wherein vitamins are naturally present or added at low concentrations and production practices may promote amorphization of the vitamin. Vitamin C is one of the most unstable vitamins in foods. This study documents that amorphous ascorbic acid is less stable than crystalline ascorbic acid in some environments (for example, higher temperatures within 1 wk), especially when the vitamin is present at low concentrations in a product. These findings increase the

  20. Development of heat-resistant neutron shielding resin for high payload metal cask

    International Nuclear Information System (INIS)

    Kamoshida, Mamoru; Hiranuma, Takeshi; Shimizu, Masashi

    2007-01-01

    A new neutron shielding resin has been developed for a dual-purpose metal cask. The resin is composed of a cycloaliphatic epoxy, anhydrous acid, catalyst, aluminum hydroxide and boron tetracarbide. Its long-term stability was verified by thermal degradation tests. Estimated weight loss of the resin during storage was about 1-2%. Because the curing reaction of epoxy and curing reagents was moderate at room temperature, a large amount of resin could be treated at one time which would lower fabrication cost. The fabrication process was verified by a full-scale mock-up test. No significant voids or cracks were found in the resin and uniform elemental composition was confirmed. (author)

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Raul Franzolin

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

  3. Enrichment and isolation of endosulfan-degrading microorganism from tropical acid soil.

    Science.gov (United States)

    Kalyani S, Surya; Sharma, Jitender; Singh, Surender; Dureja, Prem; Lata

    2009-09-01

    Endosulfan (6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano-2,3,4-benzo-dioxathiepin-3-oxide) is a cyclodiene organochlorine currently used as an insecticide all over the world and its residues are posing a serious environmental threat. This study reports the enrichment and isolation of a microbial culture capable of degrading endosulfan with minimal production of endosulfan sulfate, the toxic metabolite of endosulfan, from tropical acid soil. Enrichment was achieved by using the insecticide as sole sulfur source. The enriched microbial culture, SKL-1, later identified as Pseudomonas aeruginosa, degraded up to 50.25 and 69.77 % of alpha and beta endosulfan, respectively in 20 days. Percentage of bioformation of endosulfan sulfate to total formation was 2.12% by the 20th day of incubation. Degradation of the insecticide was concomitant with bacterial growth reaching up to an optical density of 600 nm (OD600) 2.34 and aryl sulfatase activity of the broth reaching up to 23.93 microg pNP/mL/hr. The results of this study suggest that this novel strain is a valuable source of potent endosulfan-degrading enzymes for use in enzymatic bioremediation. Further, the increase in aryl sulfatase activity of the broth with the increase in degradation of endosulfan suggests the probable involvement of the enzyme in the transformation of endosulfan to its metabolites.

  4. Thermal degradation kinetics of ascorbic acid, thiamine and riboflavin in rosehip (Rosa canina L nectar

    Directory of Open Access Journals (Sweden)

    Çetin KADAKAL

    2017-10-01

    Full Text Available Abstract In this paper, the loss of L-ascorbic acid, thiamine and riboflavin in rosehip nectar with the heating periods (0, 5, 10, 15, 20 and 30 min at temperatures ranging from 70 to 95 °C is analyzed and experimental results are presented. Firstly, dried rosehip fruits were processed to rosehip nectar and then thermal treatment is performed. Liquid chromatographic (HPLC method was used for the analysis of the contents of L-ascorbic acid, thiamine and riboflavin and examined compounds are thoroughly separated within 25 min. During thermal processing, degradation of L-ascorbic acid, thiamine and riboflavin in rosehip nectar were fitted to a first-order reaction kinetic model. Arrhenius relationship was used for the description of temperature dependence of reaction. Activation energies for L-ascorbic acid, thiamine and riboflavin between 70 to 95 ºC were found to be 55.30, 36.38 and 37.15 kJ/mol, respectively. To the best of the author’s knowledge, due to lack of study on the thermal degradation of L-ascorbic acid, thiamine and riboflavin in rosehip nectar, this manuscript will be the first reported study to enable future analysis.

  5. An approach for degradation of grape seed and skin proanthocyanidin polymers into oligomers by sulphurous acid.

    Science.gov (United States)

    Luo, Lanxin; Cui, Yan; Cheng, Jinhui; Fang, Bairui; Wei, Zongmin; Sun, Baoshan

    2018-08-01

    To develop an efficient method for degradation of grape seed and skin proanthocyanidins polymers into oligomers, an optimized sulphurous acid degradation conditions for grape seed with the temperature of 60 °C, reaction time of 60 min and sample-sulphurous acid ratio of 1:0.2, and for grape skin with the temperature of 40 °C, reaction time of 60 min and sample-sulphurous acid ratio of 1:0.2, were established. Afterwards, HSCCC and prep-HPLC were used to fractionate and isolate individual proanthocyanidin oligomers from the degradation products. Total of ten dimeric or trimeric procyanidins were obtained, and most of them presented high yield (from 0.7 mg to 13.6 mg per run in grape seed and from 0.5 mg to 4.1 mg per run in grape skin) and high purity (over 90%). The proposed method provides a new way for large preparation of oligomeric proanthocyanidins from naturally abundant and wasted polymeric ones. Copyright © 2018 Elsevier Ltd. All rights reserved.

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

    International Nuclear Information System (INIS)

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

    2012-01-01

    Anatase TiO 2 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 TiO 2 consisted of well-defined spheres with size of 3-5 μm. The photocatalytic activity of spherical TiO 2 was determined by degradation of salicylic acid under visible light irradiation. It was revealed that the degradation rate of the spherical TiO 2 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 TiO 2 (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 TiO 2 (temperature: 150, time: 48 h).

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

    Science.gov (United States)

    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

  8. High Performance Fatty Acid-Based Vinyl Ester Resin for Liquid Molding

    National Research Council Canada - National Science Library

    Geng, Xing; La Scala, John J; Sands, James M; Palmese, Guiseppe R

    2007-01-01

    ...% compared to 40-60 wt% associated with commercial products. In addition, fatty acid-based monomers can bring about other benefits like higher toughness, lower exothermal heat and low volume shrinkage...

  9. Selective sorption of ruthenium from acidic medium by Amberlite XAD 7 resin impregnated with iodide salt of N,N'-diisobutyl(α-Trialkylammonium)-acetamide

    International Nuclear Information System (INIS)

    Sharma, Shikha; Ghosh, Sunil K.; Sharma, J.N.

    2015-01-01

    This work investigates the removal of ruthenium (III) from aqueous nitric acid solutions using solvent impregnated resin (SIR). The SIR has been made by impregnating Amberlite XAD-7 with iodide salt of N,N'-diisobutyl(α-trialkylammonium)acetamide as the extractant and methanol as the solvent by a wet impregnation technique. This solvent has already been successfully investigated by us for selective extraction of ruthenium (III) from nitric acid solution by solvent extraction technique. Maximum loading of ammonium acetamide on Amberlite XAD was found to be in the ratio of 1:2. Loaded resin was characterized by IR and SEM analyses. The effect of metal ion concentration on the sorption of ruthenium (III) ions has been investigated to quantify the sorption capacity of resin for Ru. Maximum loading of ruthenium was found to be 14 mg/g of resin. Maximum K d obtained was 754. Ruthenium was successfully stripped from SIR using sodium hydroxide solution in a single contact. (author)

  10. Preparation and characterization of anion exchange resin decorated with magnetite nanoparticles for removal of p-toluic acid from aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Davarpanah, Morteza, E-mail: Davarpanah.morteza@gmail.com; Ahmadpour, Ali; Rohani Bastami, Tahereh

    2015-02-01

    Polystyrene resin was covalently functionalized with diethanolamine and then decorated with magnetite nanoparticles by a novel and simple co-precipitation method using iron(II) sulfate as precursor. The products were characterized by Fourier transform infrared spectroscopy, elemental analysis, X-ray diffraction, Mössbauer spectroscopy, field-emission scanning electron microscopy and vibrating sample magnetometer. Adsorption of p-toluic acid (p-TA) onto magnetite-decorated polystyrene (MAG-PS) was studied and compared with that of diethanolamine-functionalized polystyrene and a commercial anion exchange resin. Results showed that the magnetite nanoparticles with an average size of 20.4 nm were successfully formed on the surface of polystyrene resin, and MAG-PS was exhibited high affinity for the removal of p-TA. - Highlights: • .Polystyrene resin was covalently functionalized with diethanolamine. • .The functionalized adsorbents were decorated with magnetite nanoparticles (∼20 nm). • .Proposed magnetization procedure was high-efficient and relatively simple. • .Magnetic adsorbent was presented high affinity for removal of p-toluic acid.

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

    Science.gov (United States)

    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)

  12. Degradation Kinetics and Mechanism of Lithospermic Acid under Low Oxygen Condition Using Quantitative 1H NMR with HPLC-MS.

    Science.gov (United States)

    Pan, Jianyang; Gong, Xingchu; Qu, Haibin

    2016-01-01

    A novel quantitative 1H NMR (Q-NMR) combined with HPLC-MS method has been proposed for investigating the degradation process of traditional Chinese medicine (TCM) components. Through this method, in-situ monitoring of dynamics degradation process of lithospermic acid (LA), one of the popular polyphenolic acids in TCM, was realized under low oxygen condition. Additionally, this methodology was proved to be simple, rapid and specific. Degradation kinetic runs have been carried out to systematically investigate the effects of two key environmental factors, initial pH values and temperatures. Eight main degradation products of LA were detected, seven of which were tentatively structural elucidated with the help of both NMR and LC-MS in this work and salvianolic acid A (Sal A) was the primary degradation product of LA. A possible degradation pathway of LA was proposed, subsequently. The results showed that the degradation of LA followed pseudo-first-order kinetics. The apparent degradation kinetic constants increased as the initial pH value of the phosphate buffer increased. Under the given conditions, the rate constants of overall degradation as a function of temperature obeyed the Arrhenius equation. Our results proved that the Q-NMR combined with HPLC-MS method can be one of the most promising techniques for investigating degradation process of active components in TCM.

  13. Thermal- and photo-induced degradation of perfluorinated carboxylic acids: Kinetics and mechanism.

    Science.gov (United States)

    Liu, Jiaoqin; Qu, Ruijuan; Wang, Zunyao; Mendoza-Sanchez, Itza; Sharma, Virender K

    2017-12-01

    Perfluorinated carboxylic acids (PFCAs) of different carbon chain lengths are chemicals of concern to human health and their removal, using conventional remediation technologies, is challenging. The present paper pursuits thermal and photo-induced degradation of PFCAs (F(CF 2 ) n COOH, n = 1-9) under various concentrations of four different acids (HNO 3 , H 2 SO 4 , HCl, and H 3 PO 4 ) covering a range of strong acidic to basic pH. For thermal-induced experiments, the temperature was set at 40 °C, 60 °C, and 80 °C at acid strengths of 0.04-18.4 M. Photo-induced experiments were conducted at pH 0.5, 7.0, and 13.0 under a light intensity of (150 ± 10) × 100 μW/cm 2 . The degradation first-order rate constant (k 1, h -1 ) as a function of [H + ] was modeled by considering equilibrium of nondissociated (F(CF 2 ) n COOH, HX) and dissociated (F(CF 2 ) n COO - , X - ) species of PFCAs (HX ⇌ X -  + H + , pK a  = -0.1). Species-specific rate constants, k 1 HX , reasonably described the trend of thermal and photo decay of PFCAs, where k 1 HX increased with acidity of solution and the carbon chain length of PFCAs. Mechanism of degradation of PFCAs (e.g. perfluorooctanoic acid (PFOA)) involved homolytic breakage of CC bond between alkyl and carboxyl groups, which produced radicals and subsequently decarboxylation to perfluoroheptene-1. Density functional theory (DFT) calculations supported the mechanism. The calculations indicated that a breaking of CC bond is more feasible with nondissociated HX than dissociated X - species of PFCAs and also with increase in chain length. The potential of a combination of thermal- and photo-induced processes under acidic conditions to enhance degradation of PFOA in water is presented. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Ion-exclusion chromatographic behavior of aliphatic carboxylic acids and benzenecarboxylic acids on a sulfonated styrene--divinylbenzene co-polymer resin column with sulfuric acid containing various alcohols as eluent.

    Science.gov (United States)

    Ohta, Kazutoku; Towata, Atsuya; Ohashi, Masayoshi

    2003-05-16

    The addition of C1-C7 alcohols (methanol, ethanol, propanol, butanol, heptanol, hexanol and heptanol) to dilute sulfuric acid as eluent in ion-exclusion chromatography using a highly sulfonated styrene-divinylbenzene co-polymer resin (TSKgel SCX) in the H+ form as the stationary phase was carried out for the simultaneous separations of both (a) C1-C7 aliphatic carboxylic acids (formic, acetic, propionic, isobutyric, butyric, isovaleric, valeric, 2-methylvaleric, isocaproic, caproic, 2,2-dimethyl-n-valeric, 2-methylhexanoic, 5-methylhexanoic and heptanoic acids) and (b) benzenecarboxylic acids (pyromellitic, hemimellitic, trimellitic, o-phthalic, m-phthalic, p-phthalic, benzoic and salicylic acids and phenol). Heptanol was the most effective modifier in ion-exclusion chromatography for the improvement of peak shapes and a reduction in retention volumes for higher aliphatic carboxylic acids and benzenecarboxylic acids. Excellent simultaneous separation and relatively highly sensitive conductimetric detection for these C1-C7 aliphatic carboxylic acids were achieved on the TSKgel SCX column (150 x 6 mm I.D.) in 30 min using 0.5 mM sulfuric acid containing 0.025% heptanol as eluent. Excellent simultaneous separation and highly sensitive UV detection at 200 nm for these benzenecarboxylic acids were also achieved on the TSKgel SCX column in 30 min using 5 mM sulfuric acid containing 0.075% heptanol as eluent.

  15. [Photocatalytic reductive degradation of direct red 4BE by phosphotungstic acid].

    Science.gov (United States)

    Wei, Hong; Li, Ke-Bin; Li, Juan; Chen, Jing-Tao; Zhang, Tao

    2013-06-01

    The photoreductive degradation of Azo-dye Direct Red 4BE (4BE) in aqueous solution was studied in a batch photoreactor, with phosphatotungstic acid (H3PW12O40, PW12) as the homogeneous catalyst and isopropanol as the electron donor. The parameters such as concentrations of PW12, isopropanol and 4BE, ionic strength were carefully evaluated. The results showed that 4BE could be reductively decolorized by heteropoly blue, which was produced by phosphatotungstic acid in the presence of isopropanol under UV irradiation. The decolorization rate reached 90.39% within 50 min at a pH value of 2.0, a 4BE initial concentration of 50 mg x L(-1), a PW12 and IS concentration of 600 mg x L(-1) and 0.13 mol x L(-), respectively. The decolonization rate of 4BE increased with the increase of PW12 and isopropanol concentrations until reaching a constant value. However, the first-order rate constants k for the degradation of 4BE decreased with the increase of the 4BE initial concentration. Mutual effects were found between the concentration of isopropanol and PW12 on the photocatalytic degradation of 4BE. Moreover, the concentration of salt showed a negative effect on the photoreductive degradation of 4BE. It was assumed that the charge-transfer occurred within the complex formed by heteropoly bule and 4BE, which led to the reduction of 4BE and regeneration of heteropoly bule. This study indicates that PW12/isopropanol/UV system could be used for the reductive degradation of azo dyes.

  16. Evaluate the role of organic acids in the protection of ligands from radiolytic degradation

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Anneka [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mezyk, Stehpen [Idaho National Lab. (INL), Idaho Falls, ID (United States); Peterman, Dean [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-08-01

    In the Advanced TALSPEAK process, the bis(2-ethylhexyl)phosphoric acid (HDEHP) extractant used in the traditional TALSPEAK process is replaced by the extractant 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH[EHP]). In addition, the aqueous phase complexant and buffer used in traditional TALSPEAK is replaced with the combination of N-(2-hydroxyethyl)ethylenediamine-N,N’,N’-triacetic acid (HEDTA) and citric acid. In order to evaluate the possible impacts of gamma radiolysis upon the efficacy of the Advanced TALSPEAK flowsheet, aqueous and organic phases corresponding to the extraction section of the proposed flowsheet were irradiated in the INL test loop under an ambient atmosphere. The results of these studies conducted at INL, led INL researchers to conclude that the scarcity of values of rate constants for the reaction of hydroxyl radical with the components of the Advanced TALSPEAK process chemistry was severely limiting the interpretation of the results of radiolysis studies performed at the INL. In this work, the rate of reaction of hydroxyl radical with citric acid at several pH values was measured using a competitive pulse radiolysis technique. This report describes those results and is written in completion of milestone M3FT-16IN030102028, the goal of which was to evaluate the role of organic acids in the protection of ligands from radiolytic degradation. The results reported here demonstrate the importance of obtaining hydroxyl radical reaction rate data for the conditions that closely resemble actual solution conditions expected to be used in an actual solvent extraction process. This report describes those results and is written in completion of milestone M3FT-16IN030102028, the goal of which was to evaluate the role of organic acids in the protection of ligands from radiolytic degradation.

  17. Effect of ultrasonic degradation of hyaluronic acid extracted from rooster comb on antioxidant and antiglycation activities.

    Science.gov (United States)

    Hafsa, Jawhar; Chaouch, Mohamed Aymen; Charfeddine, Bassem; Rihouey, Christophe; Limem, Khalifa; Le Cerf, Didier; Rouatbi, Sonia; Majdoub, Hatem

    2017-12-01

    Recently, low-molecular-weight hyaluronic acid (LMWHA) has been reported to have novel features, such as free radical scavenging activities, antioxidant activities and dietary supplements. In this study, hyaluronic acid (HA) was extracted from rooster comb and LMWHA was obtained by ultrasonic degradation in order to assess their antioxidant and antiglycation activities. Molecular weight (Mw) and the content of glucuronic acid (GlcA) were used as the index for comparison of the effect of ultrasonic treatment. The effects on the structure were determined by ultraviolet (UV) spectra and Fourier transform infrared spectra (FTIR). The antioxidant activity was determined by three analytical assays (DPPH, NO and TBARS), and the inhibitory effect against glycated-BSA was also assessed. The GlcA content of HA and LMWHA was estimated at about 48.6% and 47.3%, respectively. The results demonstrate that ultrasonic irradiation decreases the Mw (1090-181 kDa) and intrinsic viscosity (1550-473 mL/g), which indicate the cleavage of the glycosidic bonds. The FTIR and UV spectra did not significantly change before and after degradation. The IC 50 value of HA and LWMHA was 1.43, 0.76 and 0.36 mg/mL and 1.20, 0.89 and 0.17 mg/mL toward DPPH, NO and TBARS, respectively. Likewise LMWHA exhibited significant inhibitory effects on the AGEs formation than HA. The results demonstrated that the ultrasonic irradiation did not damage and change the chemical structure of HA after degradation; furthermore, decreasing Mw and viscosity of LMWHA after degradation may enhance the antioxidant and antiglycation activity.

  18. Novel extracellular PHB depolymerase from Streptomyces ascomycinicus: PHB copolymers degradation in acidic conditions.

    Directory of Open Access Journals (Sweden)

    Javier García-Hidalgo

    Full Text Available 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 (PhaZ Sa , 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. PhaZ Sa 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 PhaZ Sa 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, Ser(131-Asp(209-His(269, 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. PhaZ Sa 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 PhaZ Sa make it an interesting candidate for industrial applications involving PHB degradation.

  19. Raman spectroscopy and capillary zone electrophoresis for the analysis of degradation processes in commercial effervescent tablets containing acetylsalicylic acid and ascorbic acid.

    Science.gov (United States)

    Neuberger, Sabine; Jooß, Kevin; Flottmann, Dirk; Scriba, Gerhard; Neusüß, Christian

    2017-02-05

    In order to ensure the stability of pharmaceutical products appropriate manufacturing and storage conditions are required. In general, the degradation of active pharmaceutical ingredients (APIs) and subsequent formation of degradation products affect the pharmaceutical quality. Thus, a fast and effective detection and characterization of these substances is mandatory. Here, the applicability of Raman spectroscopy and CZE for the characterization of the degradation of effervescent tablets containing acetylsalicylic acid (ASA) and ascorbic acid (AA) was evaluated. Therefore, a degradation study was performed analyzing tablets from two different manufacturers at varying conditions (relative humidity (RH) 33%, 52% and 75% at 30°C). Raman spectroscopy combined with principal component analysis could be successfully applied for the fast and easy discrimination of non-degraded and degraded effervescent tablets after a storage period of approximately 24h (RH 52%). Nevertheless, a clear identification or quantification of APIs and degradation products within the analyzed tablets was not possible, i.a. due to missing reference materials. CZE-UV enabled the quantification of the APIs (ASA, AA) and related degradation products (salicylic acid (SA); semi-quantitative also mono- and diacetylated AA) within the complex tablet mixtures. The higher the RH, the faster the degradation of ASA and AA as well as the formation of the degradation products. Mono- and diacetylated AA are major primary degradation products of AA for the applied effervescent tablets. A significant degradation of the APIs was detected earlier by CZE (6-12h, RH 52%) than by Raman spectroscopy. Summarized, Raman spectroscopy is well-suited as quick test to detect degradation of these tablets and CZE can be utilized for further detailed characterization and quantification of specific APIs and related degradation products. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Glucose-lowering effects and mechanisms of the bile acid-sequestering resin sevelamer

    DEFF Research Database (Denmark)

    Brønden, Andreas; Mikkelsen, Kristian; Sonne, David P

    2018-01-01

    and mechanism(s) of sevelamer in patients with type 2 diabetes. MATERIALS AND METHODS: In this double-blinded randomized controlled trial, we randomized 30 patients with type 2 diabetes to sevelamer (n=20) or placebo (n=10). Participants were subjected to standardized 4-hour liquid meal tests at baseline...... synthesis of bile acids, a shift towards a more hydrophilic bile acid pool and increased lipogenesis. No glucagon-like peptide-1-mediated effects on insulin, glucagon or gastric emptying were evident, which point to limited contribution of this incretin hormone to the glucose-lowering effect of sevelamer...

  1. Isolation and characterization of a diverse group of phenylacetic acid degrading microorganisms from pristine soil.

    Science.gov (United States)

    O'Connor, Kevin E; O'Leary, Niall P; Marchesi, Julian R; Dobson, Alan D W; Duetz, Wouter

    2005-11-01

    A diverse range of microorganisms capable of growth on phenylacetic acid as the sole source of carbon and energy were isolated from soil. Sixty six different isolates were identified and grouped according to 16S rRNA gene RFLP analysis. Subsequent sequencing of 16S rDNA from selected strains allowed further characterization of the phenylacetic acid degrading population isolated from soil. Nearly half (30) of the isolates are Bacillus species while the rest of the isolates are strains from a variety of genera namely, Arthrobacter, Pseudomonas, Rhodococcus, Acinetobacter, Enterobacter, Flavobacterium, and Paenibacillus. Sixty-one of the sixty-six strains reproducibly grew in defined minimal liquid culture medium (E2). All strains isolated grew when at least one hydroxylated derivative of phenylacetic acid was supplied as the carbon source, while 59 out of the 61 strains tested, accumulated ortho-hydroxyphenylacetic acid in the assay buffer; when pulsed with phenylacetic acid. Oxygen consumption experiments failed to indicate a clear link between phenylacetic acid and hydroxy-substituted phenylacetic acid in isolates from a broad range of genera.

  2. Degradation of humic acid and formation of formaldehyde in PEROXONE processes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, K.W.; Rhee, D.S. [Kangwon National University, Chunchon (Korea)

    2001-02-01

    This research was studied the action of the coupling ozone-hydrogen peroxide on aqueous humic acid. PEROXONE process is enhanced the generation of hydroxyl radicals which is effective for degradation of organic matters. Therefore the changes of UV{sub 254} and TOC were investigated through the change of concentrations, injection time of H{sub 2}O{sub 2}, initial pH of aqueous humic acid and concentrations of radical scavenger as HCO{sub 3}{sup -} in the PEROXONE processes. And the GC/ECD was used to detect the formaldehyde formed by ozonation of humic acid. From the experimental results, concentrations and injection time of H{sub 2}O{sub 2} and initial pH in solution in the PEROXONE processes were very important for enhancing the efficiency of degradation in humic acid. The results indicated that removal efficiency of TOC was the highest when concentration of H{sub 2}O{sub 2} was 5 mg/L, injection time of H{sub 2}O{sub 2} was 5 minutes and initial pH in solution was 10.5. And presence of alkalinity in solution was reduced the efficiency of treatment. The formaldehyde were formed less PEROXONE processes than only ozone. When initial pH in solution were changed from 3.5 to 10.5, the formaldehyde were formed the highest concentration at pH 5. (author). 18 refs., 12 figs.

  3. Mechanical properties, morphology, and hydrolytic degradation behavior of polylactic acid / natural rubber blends

    Science.gov (United States)

    Buys, Y. F.; Aznan, A. N. A.; Anuar, H.

    2018-01-01

    Due to its biodegradability and renewability, polylactic acid (PLA) has been receiving enormous attention as a potential candidate to replace petroleum based polymers. However, PLA has limitation due to its inherent brittleness. In order to overcome this limitation, blending PLA with elastomeric materials such as natural rubber (NR) are commonly reported. In previous, several researches on PLA/NR blend had been reported, with most of them evaluated the mechanical properties. On the other hand, study of degradation behavior is significance of importance, as controlling materials degradation is required in some applications. This research studied the effect of blend composition on mechanical properties, morphology development, and hydrolytic degradation behavior of PLA/NR blends. Various compositions of PLA/NR blends were prepared by melt blending technique. Tensile test and impact test of the blends were performed to evaluate the mechanical properties. Addition of NR improved the elongation at break and impact strength of the blends, but reduced the tensile strength and stiffness of the specimens. Dynamic Mechanical Analysis (DMA) measurements of the blends displayed two peaks at temperature -70˚C which corresponded to T g of NR and 65˚C which corresponded to T g of PLA. Field Emission Scanning Electron Microscopy (FE-SEM) micrograph of 70/30 PLA/NR specimen also showed two distinct phases, which lead to indication that PLA/NR blends are immiscible. Hydrolytic degradation behavior was evaluated by measuring the remaining weight of the samples immersed in sodium hydroxide solution for a predetermined times. It was shown that the degradation behavior of PLA/NR blends is affected by composition of the blends, with 100 PLA and 70/30 PLA/NR blend showed the fastest degradation rate and 100 NR displayed the slowest one.

  4. Impact of humic acid on the degradation of levofloxacin by aqueous permanganate: Kinetics and mechanism.

    Science.gov (United States)

    Xu, Ke; Ben, Weiwei; Ling, Wencui; Zhang, Yu; Qu, Jiuhui; Qiang, Zhimin

    2017-10-15

    Levofloxacin (LF) is a frequently detected fluoroquinolone in surface water, and permanganate (MnO 4 - ) is a commonly used oxidant in drinking water treatment. This study investigated the impact of humic acid (HA) on LF degradation by aqueous MnO 4 - from both kinetic and mechanistic aspects. In the absence of HA, the second-order rate constant (k) of LF degradation by MnO 4 - was determined to be 3.9 M -1  s -1 at pH 7.5, which increased with decreasing pH. In the presence of HA, the pseudo-first-order rate constant (k obs ) of LF degradation at pH 7.5 was significantly increased by 3.8- and 2.8-fold at [HA] o :[KMnO 4 ] o (mass ratio) = 0.5 and 1, respectively. Secondary oxidant scavenging and electron paramagnetic resonance tests indicated that HA could form a complex with Mn(III), a strongly oxidative intermediate produced in the reaction of MnO 4 - with HA, to induce the successive formation of superoxide radicals (O 2 - ) and hydroxyl radicals (OH). The resulting OH primarily contributed to the accelerated LF degradation, and the complex [HA-Mn(III)] could account for the rest of acceleration. The degradation of LF and its byproducts during MnO 4 - oxidation was mainly through hydroxylation, dehydrogenation and carboxylation, and the presence of HA led to a stronger destruction of LF. This study helps better understand the degradation of organic micropollutants by MnO 4 - in drinking water treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

    Energy Technology Data Exchange (ETDEWEB)

    Flores, Nelly; Sirés, Ignasi; Garrido, José Antonio; Centellas, Francesc; Rodríguez, Rosa María; Cabot, Pere Lluís; Brillas, Enric, E-mail: brillas@ub.edu

    2016-12-05

    Highlights: • trans-Ferulic acid degradation by EAOPs using a stirred BDD/air-diffusion cell. • Slow substrate abatement and poor mineralization by AO-H{sub 2}O{sub 2}. • 98% Mineralization by PEF, but with rapid and similar substrate decay than by EF. • Quicker degradation by SPEF due to the more potent photolytic action of sunlight. • Reaction pathway with four primary aromatic products and three final carboxylic acids. - Abstract: Solutions of pH 3.0 containing trans-ferulic acid, a phenolic compound in olive oil mill wastewater, have been comparatively degraded by anodic oxidation with electrogenerated H{sub 2}O{sub 2} (AO-H{sub 2}O{sub 2}), electro-Fenton (EF) and photoelectro-Fenton (PEF). Trials were performed with a BDD/air-diffusion cell, where oxidizing ·OH was produced from water discharge at the BDD anode and/or in the solution bulk from Fenton’s reaction between cathodically generated H{sub 2}O{sub 2} and added catalytic Fe{sup 2+}. The substrate was very slowly removed by AO-H{sub 2}O{sub 2}, whereas it was very rapidly abated by EF and PEF, at similar rate in both cases, due to its fast reaction with ·OH in the bulk. The AO-H{sub 2}O{sub 2} process yielded a slightly lower mineralization than EF, which promoted the accumulation of barely oxidizable products like Fe(III) complexes. In contrast, the fast photolysis of these latter species under irradiation with UVA light in PEF led to an almost total mineralization with 98% total organic carbon decay. The effect of current density and substrate concentration on the performance of all treatments was examined. Several solar PEF (SPEF) trials showed its viability for the treatment of wastewater containing trans-ferulic acid at larger scale. Four primary aromatic products were identified by GC–MS analysis of electrolyzed solutions, and final carboxylic acids like fumaric, acetic and oxalic were detected by ion-exclusion HPLC. A reaction sequence for trans-ferulic acid mineralization

  6. Effect of perfluorosulfonic acid membrane equivalent weight on degradation under accelerated stress conditions

    International Nuclear Information System (INIS)

    Rodgers, Marianne P.; Pearman, Benjamin P.; Mohajeri, Nahid; Bonville, Leonard J.; Slattery, Darlene K.

    2013-01-01

    The equivalent weight of proton exchange membranes has a large effect on their properties and can impact performance and durability in hydrogen fuel cells. For example, increasing the EW increases the crystallinity of perfluorosulfonic acid membranes, while water content and glass transition temperature decrease. The length of the sulfonic acid side chain also impacts membrane properties. Perfluorosulfonic acid membranes with shorter sulfonic acid side chains, though they exhibit similar gas permeability, have been shown to have higher crystallinity, higher glass transition temperature, slightly lower water content, and lower proton conductivity than membranes with longer sulfonic acid side chains for a given EW. Although many reports have investigated cell performance for membranes as a function of low EW and side chains length, their impact on cell durability is not well understood. Because side chain attack by radicals formed during fuel cell operation is a major source of membrane degradation, it is reasonable to hypothesize that membranes with lower EW and, therefore, more sulfonic acid side chains, would have lower durability. This study evaluates membrane degradation for cells containing PFSA membranes with 750 EW, 950 EW, and 1100 EW. The 750 EW membrane contained short sulfonic acid side-chains while the 950 EW and 1100 EW membranes were Nafion ® -based with long sulfonic acid side-chains. Membranes were tested in fuel cells for 100 h under open circuit voltage, at 90 °C and 30% relative humidity. Diagnostic tests conducted on the cells included hydrogen crossover, fluoride emission, catalyst electrochemical surface area, posttest membrane scanning electron microscopy/transmission electron microscopy evaluation, and defect identification in membranes. The 950 EW cell had the highest decay metrics including fluoride emission, voltage decay, loss in ECA, and loss in cell performance. In all cases, the 1100 EW cell showed the lowest degradation. This has

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

    Directory of Open Access Journals (Sweden)

    Michel Oelschlägel

    2015-06-01

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

  8. Influence of lactic acid bacteria on stereoselective degradation of theta-cypermethrin.

    Science.gov (United States)

    Shi, Kaiwei; Chen, Zenglong; Liu, Fengmao; Li, Li; Yuan, Longfei

    2018-03-01

    The purpose of this study was to investigate the influence of four kinds of Lactic acid bacteria (LAB) on stereoselective degradation of theta-cypermethrin (CYP), including Lactobacillus plantarum, Lactobacillus casei, Lactobacillus delbrueckii, and Streptococcus thermophilus. An effective analytical method for (±)-theta-CYP in medium was developed by high-performance liquid chromatography with cellulose tris-(3,5-dimethylphenylcarbamate) chiral stationary phase. theta-Cypermethrin was spiked to LAB medium with different inoculation rates and sampled at 0, 2, 8, 24, 36, 48, 72, 120, 168, and 240 hours. The results showed that LAB influenced the half-lives and enantiomer fractions of theta-CYP enantiomers, which lead a closer degradation rate between the 2 stereoisomers, and no obvious difference was found among 4 LABs. Besides, the stereoselective degradation of theta-CYP was closely related to pH. The lower the pH (pH of 3, 5, 7, and 9), the lower the enantiomer fraction (from 4.88 to 6.69). At pH of 3, 7, and 9, significant differences of half-lives between enantiomers were observed. (-)-theta-Cypermethrin decreased faster than (+)-theta-CYP under pH of 3, while opposite results were indicated under pH of 7 and 9. Moreover, the acidic condition contributed to the higher chiral configuration stability of (±)-theta-CYP. (+)-Enantiomer was influenced by pH in a greater degree than (-)-enantiomer. © 2017 Wiley Periodicals, Inc.

  9. Degradation of unglazed rough graphite-aluminium solar absorber surfaces in simulated acid and neutral rain

    International Nuclear Information System (INIS)

    Konttinen, P.; Lund, P.D.; Salo, T.

    2005-01-01

    Degradation mechanisms of unglazed solar absorber surfaces based on aluminium substrate were studied. Rough graphite-aluminium surfaces were total-immersion subjected to aerated and de-aerated simulated neutral and acid rain. Test conditions were based on calculated absorber stagnation temperature and global rain acidity measurements. Changes in optical properties, elemental composition and sample mass were examined by spectrometry, energy dispersive X-ray spectrometry and thermogravimetry, respectively. The absorbers exhibited almost no degradation at pH value of 3.5. At pH 5.5 alumina on the surface hydrated significantly degrading the optical properties of the surfaces severely in most cases. Therefore these absorber surfaces can not be recommended to be used in non-glazed applications if they are exposed to rain with pH exceeding ∼ 3.5-4.5. The total-immersion test needs to be developed further as the test results exhibited poor temperature and time dependency thus preventing accurate service lifetime estimates. Still, these tests were useful in determining favourable and non-favourable operating conditions for the absorber surfaces based on aluminium substrate. (author)

  10. Characterization of hydrolytic degradation of polylactic acid/rice hulls composites in water at different temperatures

    Directory of Open Access Journals (Sweden)

    2011-02-01

    Full Text Available Hydrolytic degradations of polylactic acid/rice hulls (PLA/RH composites with various rice hulls contents due to water absorptions at 23, 51 and 69°C were investigated by studying the thermal properties, chemical composition, molecular weight, and morphology of the degraded products. The results have attested that the stability of PLA/RH composites in water depends slightly on rice hulls contents but it is significantly influenced by water temperature. Water absorption in 30 days at 23°C was between 0.87 and 9.25% depending on rice hull contents. However, at thermophilic temperatures, the water absorption and degradation of these products were increased significantly. Saturations were achieved in less than 25 and 9 days at 51°C and 69°C, respectively, while hydrolytic degradation was demonstrated by an increase in fragility and development of crystallinity. At 69°C, there were significant reductions of the decomposition and glass transition temperatures of the polymer by 13°C. These changes were associated with the reduction of the molecular weight of PLA from 153.1 kDa to ~10.7 kDa due to hydrolysis of its ester group.

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

    Directory of Open Access Journals (Sweden)

    Mohammad Kargar

    2013-10-01

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

  12. Nucleating and Plasticization Effects in Drawn Poly(Lactic Acid Fiber during Accelerated Weathering Degradation

    Directory of Open Access Journals (Sweden)

    Masakazu Nishida

    2018-03-01

    Full Text Available Changes in the polymer properties of poly(lactic acid (PLA fibers during drawing and degradation processes were analyzed using solid-state NMR, with the goal of elucidating morphological changes that influence fiber tensile properties. Combination of X-ray diffraction (XRD and differential scanning calorimeter (DSC indicated that the drawn PLA fibers consisted of different proportions of α crystalline and amorphous forms. 13C CP-MAS NMR spectra showed amorphous-like broad singlet signals, of which the full width at half maximum (FWHM decreased with increasing crystallinity and crystal orientation. The T1H value decreased by interaction with additives and increased with increasing crystal orientation. The interaction with additives also reduced T1C values, which increased with increasing crystallinity. Use of organic clay enhanced the crystallization of high draw-ratio PLA fibers due to nucleation, which increased tensile strength; this effect gradually decreased with time during accelerated weathering. In contrast, the plasticization due to the addition of flexible polymers increased fiber elongation, which rapidly dropped during the degradation. Changes of FWHM, T1H, and T1C values indicated that the degradation occurred at sites within the amorphous portions of the PLA fibers containing organic clay, while the flexible polymers were preferentially degraded if they were present in the PLA fibers.

  13. Polymer Film-Based Screening and Isolation of Polylactic Acid (PLA)-Degrading Microorganisms.

    Science.gov (United States)

    Kim, Mi Yeon; Kim, Changman; Moon, Jungheun; Heo, Jinhee; Jung, Sokhee P; Kim, Jung Rae

    2017-02-28

    Polylactic acid (PLA) has been highlighted as an alternative renewable polymer for the replacement of petroleum-based plastic materials, and is considered to be biodegradable. On the other hand, the biodegradation of PLA by terminal degraders, such as microorganisms, requires a lengthy period in the natural environment, and its mechanism is not completely understood. PLA biodegradation studies have been conducted using mainly undefined mixed cultures, but only a few bacterial strains have been isolated and examined. For further characterization of PLA biodegradation, in this study, the PLA-degrading bacteria from digester sludge were isolated and identified using a polymer film-based screening method. The enrichment of sludge on PLA granules was conducted with the serial transference of a subculture into fresh media for 40 days, and the attached biofilm was inoculated on a PLA film on an agar plate. 3D optical microscopy showed that the isolates physically degraded the PLA film due to bacterial degradation. 16S rRNA gene sequencing identified the microbial colonies to be Pseudomonas sp. MYK1 and Bacillus sp. MYK2. The two isolates exhibited significantly higher specific gas production rates from PLA biodegradation compared with that of the initial sludge inoculum.

  14. Alkyd-amino resins based on waste PET for coating applications

    International Nuclear Information System (INIS)

    Torlakoglu, A.; Gueclue, G.

    2009-01-01

    Waste polyethylene terephthalate (PET) flakes were depolymerized by using propylene glycol (PG) in the presence of zinc acetate as catalyst. Glycolysis reaction products of waste PET obtained by using PET/glycol molar ratio 1/2. Two short oil alkyd resins of high acid values (30-40 mgKOH/g) were prepared from phthalic anhydride (PA), glycerin (G), coconut oil fatty acids (COFA) and glycolyzed products of waste PET (PET-based alkyd resins) or glycols (PG) (reference alkyd resins). These alkyd resins were blended with 30%, 40%, and 50% of a commercial urea-formaldehyde, melamine-formaldehyde and urea-formaldehyde/melamine-formaldehyde mixture (1/1 weight ratio) and heated at 140 deg. C. The physical and chemical properties such as drying time, hardness, abrasion resistance, adhesion strength, water resistance, alkaline resistance, acid resistance, gelation time, and thermal oxidative degradation resistance (with thermogravimetric analysis, TGA) of these alkyd-amino resins were investigated. The properties of the waste PET-based resins were found to be compatible with the properties of the reference resins

  15. Alkyd-amino resins based on waste PET for coating applications.

    Science.gov (United States)

    Torlakoğlu, A; Güçlü, G

    2009-01-01

    Waste polyethylene terephthalate (PET) flakes were depolymerized by using propylene glycol (PG) in the presence of zinc acetate as catalyst. Glycolysis reaction products of waste PET obtained by using PET/glycol molar ratio 1/2. Two short oil alkyd resins of high acid values (30-40mgKOH/g) were prepared from phthalic anhydride (PA), glycerin (G), coconut oil fatty acids (COFA) and glycolyzed products of waste PET (PET-based alkyd resins) or glycols (PG) (reference alkyd resins). These alkyd resins were blended with 30%, 40%, and 50% of a commercial urea-formaldehyde, melamine-formaldehyde and urea-formaldehyde/melamine-formaldehyde mixture (1/1 weight ratio) and heated at 140 degrees C. The physical and chemical properties such as drying time, hardness, abrasion resistance, adhesion strength, water resistance, alkaline resistance, acid resistance, gelation time, and thermal oxidative degradation resistance (with thermogravimetric analysis, TGA) of these alkyd-amino resins were investigated. The properties of the waste PET-based resins were found to be compatible with the properties of the reference resins.

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

    International Nuclear Information System (INIS)

    Asadieraghi, Masoud; Wan Daud, Wan Mohd Ashri

    2014-01-01

    Highlights: • HF showed interesting results on EFB (empty fruit bunches) and PMF (palm mesocarp fibre) deashing. • HCl indicated maximum ash removal from PKS (palm kernel shell). • Significant pyrolysis reactions took place at ∼250 °C to ∼400 °C. • Inorganics played a considerable catalytic role during the biomasses pyrolysis. • Acid pretreatment introduced some impacts on the biomasses structure. - Abstract: To eliminate the negative impacts of inorganic constituents during biomass thermochemical processes, leaching method by different diluted acid solutions was chosen. The different palm oil biomass samples (palm kernel shell (PKS), empty fruit bunches (EFB) and palm mesocarp fiber (PMF)) were pretreated by various diluted acid solutions (H 2 SO 4 , HClO 4 , HF, HNO 3 , HCl). Acids with the highest degrees of demineralization were selected to investigate the dematerialization impacts on the biomass thermal characteristics and physiochemical structure. Thermogravimetric analysis coupled with mass spectroscopy (TGA-MS) and Fourier transform infrared spectroscopy (TGA-FTIR) were employed to examine the biomass thermal degradation. TGA and DTG (Derivative thermogravimetry) indicated that the maximum degradation temperatures increased after acid pretreatment due to the minerals catalytic effects. The main permanent evolved gases comprising H 2 , CO 2 , CO were detected online during analysis. The major permanent gases produced at the temperature range of 250–750 °C were attributed to the condensable vapors cracking and probably some secondary reactions. The physiochemical structure change of the acid-treated biomass samples was examined by using Brunauer Emmett Teller (BET) method, Scanning Electron Microscope (SEM) and FTIR. The pyrolysis kinetics of the different palm oil biomasses were investigated using first order reaction model

  17. Physico-chemical study of the thermal degradation of ions exchange resins of nuclear origin: research of conditions to limit the pollution transfer, application to electric cables

    International Nuclear Information System (INIS)

    Antonetti, P.

    1999-01-01

    The ions exchange resins are one solid form of radioactive wastes. They are found mainly during the demineralization operations of the water from reactors cooling systems. This study aims to determine the conditions of a thermal processing leading to the production of a smaller residue, containing the whole activity. A protocol is proposed and validated on resins allowing a decrease of the volume of 63% for 99,93% of the activity. (A.L.B.)

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

    DEFF Research Database (Denmark)

    Cleemann, Lars Nilausen; Buazar, F.; Li, Qingfeng

    2013-01-01

    confirmed by the post TEM and XRD analysis. A strong dependence of the fuel cell performance degradation on the catalyst supports was observed. Graphitization of the carbon blacks improved the stability and catalyst durability though at the expense of a significant decrease in the specific surface area......Degradation of carbon supported platinum catalysts is a major failure mode for the long term durability of high temperature proton exchange membrane fuel cells based on phosphoric acid doped polybenzimidazole membranes. With Vulcan carbon black as a reference, thermally treated carbon black...... and multi‐walled carbon nanotubes were used as supports for electrode catalysts and evaluated in accelerated durability tests under potential cycling at 150 °C. Measurements of open circuit voltage, area specific resistance and hydrogen permeation through the membrane were carried out, indicating little...

  19. In vitro degradation properties of ion-beam irradiated poly(lactide-co-glycolic acid) mesh

    Science.gov (United States)

    Tanaka, Toshiyuki; Tsuchiya, Koji; Yajima, Hirofumi; Suzuki, Yoshiaki; Fukutome, Akira

    2011-10-01

    Scaffolds for tissue regeneration must be biocompatible and biodegradable. Ion-beam irradiation is useful for making polymers biocompatible, but the process by which the irradiated polymers biodegradable is not yet well understood. We investigated this phenomenon by Kr +-irradiated poly(lactide-co-glycolic acid) (PLGA) mesh substrate at an acceleration energy of 50 keV with fluences of 1 × 10 13 and 1 × 10 14 ions/cm 2. We then measured the electronic states of the constituent elements on the irradiated surface by X-ray photoelectron microscopy (XPS) and evaluated the hydrolytic degradation properties (weight loss, media pH, and tensile strength) of the mesh in phosphate buffer solution. New functional groups and carbonization were induced on the irradiated surface. Degradation rate and tensile strength remain unchanged by ion-beam irradiation. Ion-beam irradiation should, thus, be a promising modification technique for tissue engineering scaffolds.

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

    Directory of Open Access Journals (Sweden)

    Marcia Adriana Tomaz Duarte

    2014-01-01

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

  1. Application of Sonocatalyst and Sonophotocatalyst for Degradation of Acid Red 14 in Aqueous Environment

    Directory of Open Access Journals (Sweden)

    Aref Shokri

    2016-09-01

    Full Text Available Background & Aims of the Study: Azo dyes are employed in industrial processes such as textile industry to create large quantities of colored sewages that have organic and non-organic materials. So, remediation of them is essential. In this project, degradation and mineralization of Acid red 14 (AR14 that is a mono Azo dye and widely used in the textile industries was investigated by Sonocatalysis and Sono photo catalyst in the presence of homogeneous (Fe3+ photo catalyst. Materials & Methods: This study is an experimental investigation on a laboratory scale. The study performed on synthetic wastewater that hold Acid red 14.The influence of operational parameters such as initial dye concentration and ultrasonic power on the sonochemical degradation was also studied. The optimization of variables was done by one factor at a time method. Results: The efficiency of the Sonophotocatalytic process with Fe3+ was higher than Sonocatalysis and photo catalyst processes alone. The combination of sonolysis, Fe3+ and  photo catalyst caused a highly synergistic effect and the synergy index obtained for Fe3+ Sono photo catalysis was 2.05. Chemical oxygen demand (COD analysis was used to study the degree of mineralization. After 180 min of reaction, the removal of COD was 15, 25.4 and 55.5% for UV/Fe3+, US/Fe3+ and UV/US/Fe3+ process, respectively. The degradation by photocatalysis and sonolysis followed pseudo first-order with respect to the concentration of AR14. Conclusions: The results showed that the Sono photo catalytic degradation and mineralization of AR14 in the presence of Fe3+ was synergistic, most likely because of the participation of Sono-Fenton and photo-Fenton reactions.

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

    Science.gov (United States)

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

    2015-05-05

    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.

  3. Bacterial populations and environmental factors controlling cellulose degradation in an acidic Sphagnum peat.

    Science.gov (United States)

    Pankratov, Timofey A; Ivanova, Anastasia O; Dedysh, Svetlana N; Liesack, Werner

    2011-07-01

    Northern peatlands represent a major global carbon store harbouring approximately one-third of the global reserves of soil organic carbon. A large proportion of these peatlands consists of acidic Sphagnum-dominated ombrotrophic bogs, which are characterized by extremely low rates of plant debris decomposition. The degradation of cellulose, the major component of Sphagnum-derived litter, was monitored in long-term incubation experiments with acidic (pH 4.0) peat extracts. This process was almost undetectable at 10°C and occurred at low rates at 20°C, while it was significantly accelerated at both temperature regimes by the addition of available nitrogen. Cellulose breakdown was only partially inhibited in the presence of cycloheximide, suggesting that bacteria participated in this process. We aimed to identify these bacteria by a combination of molecular and cultivation approaches and to determine the factors that limit their activity in situ. The indigenous bacterial community in peat was dominated by Alphaproteobacteria and Acidobacteria. The addition of cellulose induced a clear shift in the community structure towards an increase in the relative abundance of the Bacteroidetes. Increasing temperature and nitrogen availability resulted in a selective development of bacteria phylogenetically related to Cytophaga hutchinsonii (94-95% 16S rRNA gene sequence similarity), which densely colonized microfibrils of cellulose. Among isolates obtained from this community only some subdivision 1 Acidobacteria were capable of degrading cellulose, albeit at a very slow rate. These Acidobacteria represent indigenous cellulolytic members of the microbial community in acidic peat and are easily out-competed by Cytophaga-like bacteria under conditions of increased nitrogen availability. Members of the phylum Firmicutes, known to be key players in cellulose degradation in neutral habitats, were not detected in the cellulolytic community enriched at low pH. © 2011 Society for

  4. Mechanism and kinetics of electrochemical degradation of uric acid using conductive-diamond anodes.

    Science.gov (United States)

    Dbira, Sondos; Bensalah, Nasr; Bedoui, Ahmed

    2016-12-01

    Uric acid (UA) is one of the principal effluents of urine wastewaters, widely used in agriculture as fertilizer, which is potentially dangerous and biorefractory. Hence, the degradation of UA (2,6,8-trihydroxy purine) in aqueous solution of pH 3.0 has been studied by conductive-diamond electrochemical oxidation. Hydroxyl radicals formed from water oxidation at the surface of boron-doped diamond anodes were the main oxidizing agents. Effects of current density and supporting electrolyte on the degradation rate and process efficiency are assessed. Results show that the increase of current density from 20 to 60 mA cm(-2) leads to a decrease in the efficiency of the electrochemical process. In addition, the best degradation occurred in the presence of NaCl as conductive electrolyte. Interestingly, an almost total mineralization of 50 ppm UA was obtained when anodic oxidation was performed at low current densities (20 mA cm(-2)) and in the presence of NaCl. This result confirmed that the electrolysis using diamond anodes is a very interesting technology for the treatment of UA. The identification of UA transformation products was performed by high-performance liquid chromatography (HPLC). HPLC analysis of treated solutions revealed that oxalic acid and urea were the two intermediates found. Oxalic acid was the most persistent product. Based on detected intermediates and bibliographic research, a mechanism of UA mineralization by anodic oxidation has been proposed. Ionic chromatography analysis confirmed the release of [Formula: see text] and [Formula: see text] ions during UA mineralization.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-07-01

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

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    Degradation tests of two phosphoric acid (PA) doped PBI membrane based HT-PEM fuel cells were reported in this paper to investigate the effects of start/stop and the presence of methanol in the fuel to the performance degradation of the HT-PEM fuel cell. Continuous tests with pure dry H2 and meth......Degradation tests of two phosphoric acid (PA) doped PBI membrane based HT-PEM fuel cells were reported in this paper to investigate the effects of start/stop and the presence of methanol in the fuel to the performance degradation of the HT-PEM fuel cell. Continuous tests with pure dry H2...... to the corrosion of carbon support in the catalyst layer and degradation of the PBI membrane. During the continuous test with methanol containing H2 as the fuel the reaction kinetic resistance and mass transfer resistance of both single cells increased, which may be caused by the adsorption of methanol...

  7. Role of degradation products of chlorogenic acid in the antioxidant activity of roasted coffee.

    Science.gov (United States)

    Kamiyama, Masumi; Moon, Joon-Kwan; Jang, Hae Won; Shibamoto, Takayuki

    2015-02-25

    Antioxidant activities of brewed coffees prepared from six commercial brands ranged from 63.13 ± 1.01 to 96.80 ± 1.68% at the highest levels tested. Generally, the degree of antioxidant activity of the brewed coffee was inversely proportional to the total chlorogenic acid concentration. A sample obtained from the major chlorogenic acid, 5-caffeoylquinic acid (5-CQA), heated at 250 °C exhibited potent antioxidant activity (79.12 ± 2.49%) at the level of 10 μg/mL, whereas unheated 5-CQA showed only moderate antioxidant activity (44.41 ± 0.27%) at the level of 100 μg/mL. Heat produced relatively high levels of pyrocatechol (2,809.3 μg/g) and 2-methoxy-4-vinylphenol (46.4 μg/g) from 5-CQA, and their antioxidant activity levels were 76.57 ± 3.00 and 98.63 ± 0.01%, respectively. The results of the present study suggest that roasting degrades chlorogenic acids to form potent antioxidants and thus plays an important role in the preparation of high-antioxidant low-acid coffee.

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

    International Nuclear Information System (INIS)

    Atanasov, I.; Gribachev, P.

    1997-01-01

    This study assesses the damage of soils caused by spills of sulfuric acid solutions used for in situ leaching of uranium at eight uranium producing (by open-cast method) sites (total area of approximately 220 ha) in the region of Momino-Rakovski (South Bulgaria). The upper soil layer is cinnamonic pseudopodzolic ( or Eutric Planosols by FAO Legend, 1974). The results of the investigation show that the sulfuric acid spills caused strong acidification of upper (0-20 cm) and subsurface (20-60 cm) soil horizons which is expressed as decreasing of pH (H 2 O) to 2.9-3.5 and increasing of exchangeable H + and Al 3+ to 18 and 32% from CEC. Acid degradation of soils is combined with reducing of organic matter content. The average concentration of the total heavy metal content in the upper soil horizon (in ppm) is: Cd=1.5; Cu=30; Pb=25; Zn=40 and U=8. No significant differences were detected between the upper and subsurface soil layers . The heavy metal concentration did not exceed the Bulgarian standards for heavy metals and uranium content of soils. But the coarse texture of the top soil layers, the lack of carbonates, The low CEC and strong acidity determine a low buffering capacity of the investigated soils and this can be considered as hazardous for plants. This indicates that a future soil monitoring should be carried out in the region together with measures for neutralizing of soil acidity

  9. Optimal sulphuric acid production using Acidithiobacillus caldus ...

    African Journals Online (AJOL)

    Optimal sulphuric acid production using Acidithiobacillus caldus (DSM 8584): Bioprocess design for application in ion-exchange. ... Secondly, after 80% (v/v) moisture loss from the recovered biological H2SO4 titres, the acid solution was used for the recovery of nuclear grade lithium 7 (7Li+) from a degraded resin, ...

  10. Preconcentration and determination of trace metal ions from aqueous samples by newly developed gallic acid modified Amberlite XAD-16 chelating resin.

    Science.gov (United States)

    Sharma, R K; Pant, Parul

    2009-04-15

    Gallic acid was immobilized on Amberlite XAD-16 by coupling it through -N=N group. The resulting chelating resin Amberlite XAD-16 gallic acid, characterized by thermogravimetric analysis (TGA), infrared (IR) spectra and BET analysis, was used to preconcentrate Cr(III), Mn(II),Fe(III),Co(II), Ni(II) and Cu(II)ions. The resin was employed for the preconcentration of the metal ions present in river water and industrial area aqueous samples. Several parameters like effect of pH, effect of time, effect of sample volume and flow rate of sample were investigated. The sorption capacities for the resin were 216 micromol g(-1), 180 micromol g(-1), 403 micromol g(-1), 281 micromol g(-1), 250 micromol g(-1) and 344 micromol g(-1) for Cr(III), Mn(II), Fe(III), Co(II), Ni(II) and Cu(II) respectively. The preconcentration factors for Cr(III), Mn(II), Fe(III), Ni(II), Co(II) and Cu(II) were found out to be 300, 200, 400, 285.7, 300 and 400 respectively. The effect of various interfering ions was also studied. Results were validated by using standard addition method for river water sample.

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

    Science.gov (United States)

    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. Copyright © 2016. Published by Elsevier Inc.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-07-01

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

  13. Characterization of long-chain fatty-acid-degrading syntrophic associations from a biodegraded oil reservoir.

    Science.gov (United States)

    Grabowski, Agnès; Blanchet, Denis; Jeanthon, Christian

    2005-08-01

    Molecular methods were used to characterize stearate- and heptadecanoate-degrading methanogenic consortia enriched from a low-temperature biodegraded oil field. Stearate- and heptadecanoate-degrading cultures formed acetate. Growth on heptadecanoate was also accompanied by the production of propionate. These fermentation products were transiently accumulated at the beginning of the exponential phase and were further consumed with the concomitant production of methane. Clone libraries of bacterial and archaeal 16S rRNA genes were generated for each stable enrichment. Our 16S rRNA gene-cloning analysis combined with fluorescence in situ hybridization revealed that the predominant microorganisms in the associations were affiliated with a clone cluster close to the genus Syntrophus in the class "Deltaproteobacteria" and with the methanogenic genera Methanocalculus and Methanosaeta. Confocal scanning laser microscopy showed that the bacterial and archaeal cells formed compact aggregates around the insoluble substrates. No layered structure was observed in the aggregate organization. This study reports the presence of new fatty-acid-degrading syntrophic consortia in oil fields and our results suggest that such associations may have an important ecological role in oil fields under methanogenic conditions.

  14. Kinetic study of adsorption and degradation of aniline, benzoic acid, phenol, and diuron in soil suspensions

    International Nuclear Information System (INIS)

    Dao, T.H.; Lavy, T.L.

    1987-01-01

    Laboratory studies were conducted to investigate the effects of low temperature and accelerated soil-solution contact on soil adsorption of labile organic chemicals. The authors measured the kinetics of adsorption and degradation of 14 C-aniline, 14 C-benzoic acid, 14 C-phenol, and 14 C-diuron in the solution phase at 3 and 22 0 C. In the initial stages of reactions, the adsorption of all four chemicals was instantaneous at both temperatures under accelerated soil and solution mixing. A steady state was observed after the onset of equilibrium for the adsorption reaction for all compounds within 10 to 30 min. Its length varied according to the expected order of susceptibility to microbial degradation, i.e., diuron > aniline > phenol ≥ benzoate. It was apparent that the steady-state period without or in combination with low temperature could be advantageously used to obtain adsorption measurements in microbially active systems. A mechanistic sorption-catalyzed degradation model was evaluated to uncouple mathematically these processes. The model described satisfactorily the disappearance of labile chemicals in soil suspensions. Numerical analysis allowed the concurrent determination of adsorption, desorption, and biodegradation rate coefficients

  15. LIPID PHOSPHATE PHOSPHOHYDROLASE TYPE 1 (LPP1) DEGRADES EXTRACELLULAR LYSOPHOSPHATIDIC ACID IN VIVO

    Science.gov (United States)

    Tomsig, Jose L.; Snyder, Ashley H.; Berdyshev, Evgeny V.; Skobeleva, Anastasia; Mataya, Chifundo; Natarajan, Viswanathan; Brindley, David N.; Lynch, Kevin R.

    2009-01-01

    Lysophosphatidic acid (LPA) is a lipid mediator that stimulates cell proliferation and growth and is involved in physiological and pathological processes such as wound healing, platelet activation, angiogenesis and the growth of tumors. Therefore, defining the mechanisms of LPA production and degradation are of interest in understanding the regulation of these processes. Extracellular LPA synthesis is relatively well understood whereas the mechanisms of its degradation are not. One route of LPA degradation is de-phosphorylation. A candidate enzyme is the integral membrane exophosphatase lipid phosphate phosphohydrolase type 1 (LPP1). We report here the development of a mouse wherein the LPP1 gene (Ppap2a) was disrupted. The homozygous mice, which are phenotypically unremarkable, generally lack LPP1 mRNA and multiple tissues exhibit a substantial (35–95%) reduction in LPA phosphatase activity. Compared to wild type littermates, Ppap2atr/tr animals have increased levels of plasma LPA and LPA injected intravenously is metabolized at a four-fold slower rate. Our results demonstrate that LPA is rapidly metabolized in the bloodstream and that LPP1 is an important determinant of this turnover. These results indicate that LPP1 is a catabolic enzyme for LPA in vivo. PMID:19215222

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

    International Nuclear Information System (INIS)

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

    2010-01-01

    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.

  17. Degradation of nucleic acids with ozone. II. Degradation of yeast RNA, yeast phenylalanine tRNA and tobacco mosaic virus RNA.

    Science.gov (United States)

    Shinriki, N; Ishizaki, K; Ikehata, A; Yoshizaki, T; Nomura, A; Miura, K; Mizuno, Y

    1981-10-27

    The degradation of a mixture of four 5'-ribonucleotides (AMP, GMP, CMP and UMP), yeast RNA, yeast phenylalanine tRNA, and tobacco mosaic virus RNA (TMV-RNA) with ozone (concentration in inlet gas, 0.1-0.5 mg/l) was examined in a phosphate buffer (pH 6.9). In the case of the mixture, GMP alone was degraded in the initial stage. In the ozonization of yeast RNA, the guanine moiety was less vulnerable to attack by ozone than in the case of free GMP, but it again degraded most rapidly among the four nucleotides. In the treatment of tRNA with ozone, the guanine moiety degraded first. When the numbers of degraded nucleotides reached 4.8 (remaining amino acid acceptor activity was 3.6%), the polyacrylamide gel electrophoresis of the ozonized tRNA gave a single band with the same mobility as that of the intact tRNA. It is evident that ozonolysis of tRNA proceeded without cleavage of the polynucleotide chain. In the case of TMV-RNA, the loss of the infectivity by ozone proceeded rapidly within 30 min and was followed by preferential degradation of the guanine moiety. The outstanding lability of the guanine moiety observed in each case is discussed in connection with the inactivation of tRNA and TMV-RNA.

  18. Resin glycosides from Porana duclouxii.

    Science.gov (United States)

    Ding, Wen-Bing; Zhang, Dai-Gui; Liu, Chun-Jie; Li, Guan-Hua; Li, You-Zhi

    2014-01-01

    A new intact resin glycoside (3) and two glycosidic acids (1 and 2), all having a common trisaccharide moiety and (11S)-hydroxytetradecanoic acid or (3S,11S)-dihydroxytetradecanoic acid as the aglycone, were obtained from the roots of Porana duclouxii. Their structures were elucidated by spectroscopic analyses and chemical correlations. These compounds represent the first examples of resin glycosides from the genus Porana.

  19. Analysis of hydroxycinnamic acid degradation in Agrobacterium fabrum reveals a coenzyme A-dependent, beta-oxidative deacetylation pathway.

    Science.gov (United States)

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

    2014-06-01

    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.

  20. Effect of the Acidic Dental Resin Monomer 10-methacryloyloxydecyl Dihydrogen Phosphate on Odontoblastic Differentiation of Human Dental Pulp Cells.

    Science.gov (United States)

    Kim, Eun-Cheol; Park, Haejin; Lee, Sang-Im; Kim, Sun-Young

    2015-11-01

    Although 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) is frequently used as an acidic resin monomer in dental adhesives, its effect on dental pulp cells (DPCs) has been rarely reported. The purpose of this study was to examine the effects of 10-MDP on the inflammatory response and odontoblastic differentiation of DPCs at minimally toxic concentrations. We found that 10-MDP caused the release of inflammatory cytokines including NO, PGE2, iNOS, COX-2, TNF-α, IL-1β, IL-6 and IL-8 in a concentration-dependent manner. In addition, 10-MDP reduced alkaline phosphatase activity, mineralization nodule formation and mRNA expression of odontoblastic differentiation markers such as dentin sialophosphoprotein, dentin matrix protein-1, osterix and Runx2 in a concentration-dependent manner with low toxicity. In addition, 10-MDP induced activation of nuclear factor-E2-related factor 2 (Nrf2) and its target gene, haeme oxygenase-1 (HO-1). We evaluated whether the effect of 10-MDP was related to the induction of HO-1 and found that treatment with a selective inhibitor of HO-1 reversed the production of 10-MDP-mediated pro-inflammatory cytokines and the inhibition of differentiation markers. Pre-treatment with either a GSH synthesis inhibitor or antioxidants blocked 10-MDP-induced mitogen-activated protein kinases (MAPKs), Nrf2 and NF-κB pathways. Taken together, the results of this study showed that minimally toxic concentrations of 10-MDP promoted an inflammatory response and suppressed odontoblastic differentiation of DPCs by activating Nrf2-mediated HO-1 induction through MAPK and NF-κB signalling. © 2015 Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).

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

    Science.gov (United States)

    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. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Removal of nalidixic acid and its degradation products by an integrated MBR-ozonation system.

    Science.gov (United States)

    Pollice, A; Laera, G; Cassano, D; Diomede, S; Pinto, A; Lopez, A; Mascolo, G

    2012-02-15

    Chemical-biological degradation of a widely spread antibacterial (nalidixic acid) was successfully obtained by an integrated membrane bioreactor (MBR)-ozonation process. The composition of the treated solution simulated the wastewater from the production of the target pharmaceutical, featuring high salinity and a relevant concentration of sodium acetate. Aim of treatment integration was to exploit the synergistic effects of chemical oxidation and bioprocesses, by adopting the latter to remove most of the COD and the ozonation biodegradable products. Integration was achieved by placing ozonation in the recirculation stream of the bioreactor effluent. The recirculation flow rate was three-fold the MBR feed, and the performance of the integrated system was compared to the standard polishing configuration (single ozonation step after the MBR). Results showed that the introduction of the ozonation step did not cause relevant drawbacks to both biological and filtration processes. nalidixic acid passed undegraded through the MBR and was completely removed in the ozonation step. Complete degradation of most of the detected ozonation products was better achieved with the integrated MBR-ozonation process than using the sequential treatment configuration, i.e. ozone polishing after MBR, given the same ozone dosage. Copyright © 2011 Elsevier B.V. All rights reserved.

  3. Volatile fatty acid degradation kinetics in anaerobic process; Cinetica de la degradacion de acidos grasos volatiles en procesos anaerobios

    Energy Technology Data Exchange (ETDEWEB)

    Riscado, S.; Osuna, B.; Iza, J.; Ruiz, E. [Universidad del Pais Vasco. Bilbao (Spain)

    1998-10-01

    While searching for the optimal substrate load for anaerobic toxicity assays, the inhibition caused by the propionic acid has been addressed. Lab scale experiments have been carried out to assess the effects of different loads and acid ratios. Results bad been subjected to kinetic analysis and show the degradation follows a first order kinetic, and acetic is easier to degrade than propionic acid. The optimal load for a 100 ml vial assay is composed of 158 mg COD of the 3:1:1 HAc:HPr:HBu mixture. (Author) 9 refs.

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

    Science.gov (United States)

    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).

  5. Use of a phenolic-carboxylic acid cation resin in the treatment of low-level liquid waste at Oak Ridge National Laboratory

    International Nuclear Information System (INIS)

    Chilton, J.M.

    1981-09-01

    The loading capacity of CS-100 resin, using plant waste as feed, was found to be significantly reduced after 20 loading-elution cycles; one-fourth or less of the original capacity was retained after 30 cycles. No important differences were noted between an untreated column and a column that had been reconverted to the sodium form in the regeneration step. Omission of the sodium regeneration could not be adopted as a routine procedure because it produced a packing effect in the plant beds; however, reconversion to the sodium form is now achieved by using a stoichiometric amount of caustic rather than a 100% excess, as was previous practice. Since the distribution coefficients for calcium and strontium are about six times greater than that for cesium, no loss of 90 Sr would be expected while 137 Cs is loading. Laboratory results obtained by using plant conditions and feed indicate that a typical bed would remove 96% of 90 Sr in the feed. Cobalt-60 is generally the greatest contributor to the radioactivity of the plant effluent. Laboratory tests indicate that this 60 Co is present as a mixture of a soluble anionic complex and insoluble colloids. The anionic complex could be removed by placing an anion exchange column in the effluent from the CS-100 resin bed. In studies of the dynamics of loading on CS-100 resin, the contact time in plant operation (3 to 4 min per column volume) was found to be more than adequate to obtain the desired results. Effects of flow velocity were not investigated. Data from a series of laboratory experiments show that CS-100 resin can be eluted satisfactorily with 0.5 to 1.0 M formic or acetic acid, although a larger volume is required than for elution with 0.5 M nitric acid

  6. Degradation of acetic acid with sulfate radical generated by persulfate ions photolysis.

    Science.gov (United States)

    Criquet, Justine; Leitner, Nathalie Karpel Vel

    2009-09-01

    The photolysis of S(2)O(8)(2-) was studied for the removal of acetic acid in aqueous solution and compared with the H(2)O(2)/UV system. The SO(4)(-) radicals generated from the UV irradiation of S(2)O(8)(2-) ions yield a greater mineralization of acetic acid than the ()OH radicals. Acetic acid is oxidized by SO(4)(-) radicals without significant formation of intermediate by-products. Increasing system pH results in the formation of ()OH radicals from SO(4)(-) radicals. Maximum acetic acid degradation occurred at pH 5. The results suggest that above this pH, competitive reactions with the carbon mineralized inhibit the reaction of the solute with SO(4)(-) and also ()OH radicals. Scavenging effects of two naturally occurring ions were tested; in contrast to HCO(3)(-) ions, the presence of Cl(-) ions enhances the efficiency of the S(2)O(8)(2-)/UV process towards the acetate removal. It is attributed to the formation of the Cl() radical and its great reactivity towards acetate.

  7. Radiolytic degradation of gallic acid and its derivatives in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Melo, R. [Instituto Tecnologico e Nuclear, UCQR, Estrada Nacional No. 10, Apartado 21, 2686-953, Sacavem (Portugal); Leal, J.P. [Instituto Tecnologico e Nuclear, UCQR, Estrada Nacional No. 10, Apartado 21, 2686-953, Sacavem (Portugal); Centro Quimica e Bioquimica, Faculdade de Ciencias da Universidade de Lisboa, 1749-016 Lisboa (Portugal); Takacs, E., E-mail: takacs@iki.kfki.hu [Institute of Isotopes, Hungarian Academy of Sciences, P.O. Box 77, H-1525 Budapest (Hungary); Wojnarovits, L. [Institute of Isotopes, Hungarian Academy of Sciences, P.O. Box 77, H-1525 Budapest (Hungary)

    2009-12-30

    Polyphenols, like gallic acid (GA) released in the environment in larger amount, by inducing some unwanted oxidations, may constitute environmental hazard: their concentration in wastewater should be controlled. Radiolytic degradation of GA was investigated by pulse radiolysis and final product techniques in dilute aqueous solution. Subsidiary measurements were made with 3,4,5-trimethoxybenzoic acid (TMBA) and 3,4,5-trihydroxy methylbenzoate (MGA). The hydroxyl radical and hydrogen atom intermediates of water radiolysis react with the solute molecules yielding cyclohexadienyl radicals. The radicals formed in GA and MGA solutions in acid/base catalyzed water elimination decay to phenoxyl radicals. This reaction is not observed in TMBA solution. The hydrated electron intermediate of water decomposition adds to the carbonyl oxygen, the anion thus formed protonates on the ring forming cyclohexadienyl radical or on the carbonyl group forming carbonyl centred radical. The GA intermediates formed during reaction with primary water radicals in presence of oxygen transform to non-aromatic molecules, e.g., to aliphatic carboxylic acids.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-12-31

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

  9. Degradation and Mineralization of Benzohydroxamic Acid by Synthesized Mesoporous La/TiO2

    Directory of Open Access Journals (Sweden)

    Xianping Luo

    2016-10-01

    Full Text Available Rare earth element La-doped TiO2 (La/TiO2 was synthesized by the sol-gel method. Benzohydroxamic acid was used as the objective pollutant to investigate the photocatalytic activity of La/TiO2. The physicochemical properties of the prepared materials were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectroscopy, specific surface area and porosity, scanning electron microscopy and transmission electron microscopy. As a result, the doping of La could inhibit the crystal growth of TiO2, increase its specific surface area and expand its response to visible light, thus improving its photocatalytic activity. La/TiO2 with the doping ratio of 0.75% calcined at 500 °C, showing the highest photocatalytic activity to degrade benzohydroxamic acid under the irradiation of 300 W mercury lamp. About 94.1% of benzohydroxamic acid with the original concentration at 30 mg·L−1 was removed after 120 min in a solution of pH 4.4 with an La/TiO2 amount of 0.5 g·L−1. Furthermore, 88.5% of the total organic carbon was eliminated after 120 min irradiation. In addition, after four recycling runs, La/TiO2 still kept high photocatalytic activity on the photodegradation of benzohydroxamic acid. The interfacial charge transfer processes were also hypothesized.

  10. Action of ionizing radiation on epoxy resins

    Energy Technology Data Exchange (ETDEWEB)

    Van de Voorde, M. E.

    1970-12-01

    The resistance of classical and experimental epoxy resins to irradiation was studied. The resistance to irradiation of epoxy resins of diverse compositions as well as the development of resins having a radioresistance that approaches that of certain ceramics are discussed. Sources of irradiation and the techniques of dosimetry used are described. The structures of certain epoxy resins and of hardeners are given. The preparation of these resins and their physical properties is described. The effects of radiation on epoxy resins, as well as conditions of irradiation, and suggested mechanisms for degradation of the irradiated resins are discussed. The relationship between chemical structure of the resins and their physical properties is evaluated. (115 references) (JCB)

  11. Effect of acid etching duration on tensile bond strength of composite resin bonded to erbium:yttrium-aluminium-garnet laser-prepared dentine. Preliminary study.

    Science.gov (United States)

    Chousterman, M; Heysselaer, D; Dridi, S M; Bayet, F; Misset, B; Lamard, L; Peremans, A; Nyssen-Behets, C; Nammour, S

    2010-11-01

    The purpose of this study was to compare the tensile bond strength of composite resin bonded to erbium:yttrium-aluminium-garnet (Er:YAG) laser-prepared dentine after different durations of acid etching. The occlusal third of 68 human third molars was removed in order to expose the dentine surface. The teeth were randomly divided into five groups: group B (control group), prepared with bur and total etch system with 15 s acid etching [37% orthophosphoric acid (H(3)PO(4))]; group L15, laser photo-ablated dentine (200 mJ) (laser irradiation conditions: pulse duration 100 micros, air-water spray, fluence 31.45 J/ cm(2), 10 Hz, non-contact hand pieces, beam spot size 0.9 mm, irradiation speed 3 mm/s, and total irradiation time 2 x 40 s); group L30, laser prepared, laser conditioned and 30 s acid etching; group L60, laser prepared, laser conditioned and 60 s acid etching; group L90, laser prepared, laser conditioned and 90 s acid etching. A plot of composite resin was bonded onto each exposed dentine and then tested for tensile bond strength. The values obtained were statistically analysed by analysis of variance (ANOVA) coupled with the Tukey-Kramer test at the 95% level. A 90 s acid etching before bonding showed the best bonding value (P < 0.05) when compared with all the other groups including the control group. There is no significance difference between other groups, nor within each group and the control group. There was a significant increase in tensile bond strength of the samples acid etched for 90 s.

  12. Development of Fully Degradable Phosphonium-Functionalized Amphiphilic Diblock Copolymers for Nucleic Acids Delivery.

    Science.gov (United States)

    Borguet, Yannick P; Khan, Sarosh; Noel, Amandine; Gunsten, Sean P; Brody, Steven L; Elsabahy, Mahmoud; Wooley, Karen L

    2018-03-11

    To expand the range of functional polymer materials to include fully hydrolytically degradable systems that bear bioinspired phosphorus-containing linkages both along the backbone and as cationic side chain moieties for packaging and delivery of nucleic acids, phosphonium-functionalized polyphosphoester- block-poly(l-lactide) copolymers of various compositions were synthesized, fully characterized, and their self-assembly into nanoparticles were studied. First, an alkyne-functionalized polyphosphoester- block-poly(l-lactide) copolymer was synthesized via a one pot sequential ring opening polymerization of an alkyne-functionalized phospholane monomer, followed by the addition of l-lactide to grow the second block. Second, the alkynyl side groups of the polyphosphoester block were functionalized via photoinitiated thiol-yne radical addition of a phosphonium-functionalized free thiol. The polymers of varying phosphonium substitution degrees were self-assembled in aqueous buffers to afford formation of well-defined core-shell assemblies with an average size ranging between 30 and 50 nm, as determined by dynamic light scattering. Intracellular delivery of the nanoparticles and their effects on cell viability and capability at enhancing transfection efficiency of nucleic acids (e.g., siRNA) were investigated. Cell viability assays demonstrated limited toxicity of the assembly to RAW 264.7 mouse macrophages, except at high polymer concentrations, where the polymer of high degree of phosphonium functionalization induced relatively higher cytotoxicity. Transfection efficiency was strongly affected by the phosphonium-to-phosphate (P + /P - ) ratios of the polymers and siRNA, respectively. The AllStars Hs Cell Death siRNA complexed to the various copolymers at a P + /P - ratio of 10:1 induced comparable cell death to Lipofectamine. These fully degradable nanoparticles might provide biocompatible nanocarriers for therapeutic nucleic acid delivery.

  13. Adsorption kinetics, isotherm, and thermodynamics studies of acetyl-11-keto-β-boswellic acids (AKBA) from Boswellia serrata extract using macroporous resin.

    Science.gov (United States)

    Niphadkar, Sonali S; Rathod, Virendra K

    2017-09-14

    An acetyl-11-keto-β-boswellic acid (AKBA) is potent anti-inflammatory agent found in Boswellia serrata oleogum resin. Adsorption characteristics of AKBA from B. serrata were studied using macroporous adsorbent resin to understand separation and adsorption mechanism of targeted molecules. Different macroporous resins were screened for adsorption and desorption of AKBA and Indion 830 was screened as it showed higher adsorption capacity. The kinetic equations were studied and results showed that the adsorption of AKBA on Indion 830 was well fitted to the pseudo first-order kinetic model. The influence of two parameters such as temperature (298, 303, and 308 K) and pH (5-8) on the adsorption process was also studied. The experimental data was further investigated using Langmuir, Freundlich, and Temkin isotherm models. It was observed that Langmuir isotherm model was found to be the best fit for AKBA adsorption by Indion 830 and highest adsorption capacity (50.34 mg/g) was obtained at temperature of 303 K. The values of thermodynamic parameters such as the change of Gibbs free energy (ΔG*), entropy (ΔS*), and enthalpy (ΔH*), indicated that the process of adsorption was spontaneous, favourable, and exothermic.

  14. Ion exchange removal of chromium (iii) from tannery wastes by using a strong acid cation exchange resin amberlite ir-120 h+ and its hybrids

    International Nuclear Information System (INIS)

    Ahmad, T.

    2014-01-01

    A strong acid cation exchange resin Amberlite IR-120 H+ and its hybrids with Mn(OH)/sub 2/, Cu(OH)/sub 2/ and Fe(OH)/sub 3/ are used for the removal of chromium (III) from spent tannery bath. The experimental data give good fits with the Langmuir sorption model. The thermodynamic parameters entropy (delta S), enthalpy (delta H) and free energy (delta G) changes are computed, which reveal that the chromium removal from tannery wastes by ion exchangers is an endothermic, physical sorption and entropically driven process. The rate of sorption is found to increase with the increase of resin dosage, stirring speed and temperature. Different kinetic models such as film diffusion, particle diffusion and Lagergren pseudo first order are used to evaluate the mechanism of the process. It is found that the hybrid ion exchange resins have better removal capacity as compared to the parent ion exchanger. The increase in the removal capacity is found to be in the order of the corresponding PZC values of the hybrid ion exchangers. Further, it is suggested that the higher exchange capacity is the result of Donnan effect and specific adsorption of chromium by the oxides / hydroxides present inside the matrix of the organic cation exchanger. (author)

  15. The Effect of Chemodenervation by Botulinum Neurotoxin on the Degradation of Hyaluronic Acid Fillers: An Experimental Study.

    Science.gov (United States)

    Küçüker, İsmail; Aksakal, Ibrahim Alper; Polat, Ahmet Veysel; Engin, Murat Sinan; Yosma, Engin; Demir, Ahmet

    2016-01-01

    Early degradation is a common complaint for hyaluronic acid fillers. Although the combination of hyaluronic acid fillers with botulinum neurotoxin type A presented improved clinical results, objective measurement of hyaluronic acid volumes has not been previously assessed. In this study, the authors have split the calvaria of the rabbit to mimic the glabellar region in humans. In this model, the authors applied hyaluronic acid alone to one side and hyaluronic acid combined with botulinum neurotoxin type A to the contralateral side. Two days and 3 months after the filler injection, magnetic resonance imaging was performed to assess the filler volumes. Average initial volume of filler only and filler combined with botulinum neurotoxin type A was 0.61 cm on both sides, and there was no difference between initial volumes of the two sides (p = 0.735). At the end of 3 months, average degraded volumes of filler-only and filler combined with botulinum neurotoxin sides were 0.33 cm and 0.19 cm, respectively, and the degradation difference was significant between the two groups (p = 0.001). End volumes for the filler-only and filler combined with botulinum neurotoxin sides were 0.28 cm and 0.42 cm, respectively, and end volumes between two sides were also statistically significant (p neurotoxin type A significantly decreases the degradation process and increases the remaining volume of the hyaluronic acid fillers at the end of the paralyzed period.

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

    Directory of Open Access Journals (Sweden)

    Joey Andrew A. Valinton

    2016-06-01

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

  17. Degradation of polylactic acid (Pla) at different doses of gamma radiation

    International Nuclear Information System (INIS)

    Castillo R, Y.

    2015-01-01

    The excessive use of polymers such as polyethylene (PET), polystyrene (Ps) and recently the polylactic acid (Pla) that take more than 20 years to degrade, have caused great pollution in the environment. In this study the effects of gamma radiation in the Pla to different doses were studied, in order to reduce the degradation time of this polymer. The changes in physico-chemical structure of Pla during radiation were studied by thermo-gravimetric/Mass analysis; differential scanning calorimetry; scanning electron microscopy; X-ray dispersive analysis; infrared spectroscopy; X-ray diffraction and mechanical tests of hardness, elasticity and deformation. With scanning electron microscopy, the morphology of the Pla surface unirradiated was observed, in which an apparently smooth surface was observed, after changes that had the Pla when irradiated also was observed, where the effects of radiation were observed in form of scratch, agglomeration and small fractures. By X-ray dispersive analysis was determined and verified the elemental chemical composition of the Pla; as expected the tests showed only carbon, oxygen and hydrogen. With thermo-gravimetric/Mass analysis the decomposition temperatures of Pla were determined, identifying that the degradation compounds are CO, CO 2 and CH 4 . With infrared spectrometry the major peaks of Pla were observed before and after being irradiated with increasing of radiation dose the intensity of the bands decreased. Also by X-ray diffraction was observed that the polymer is an amorphous material. The mechanical tests indicate that the values of each of the tests decrease significantly with increasing the radiation dose. (Author)

  18. Theoretical and spectroscopic investigation of the oxidation and degradation of protocatechuic acid

    International Nuclear Information System (INIS)

    Hatzipanayioti, Despina; Karaliota, Alexandra; Kamariotaki, Mary; Aletras, Vasilios; Petropouleas, Panayiotis

    2006-01-01

    In this work, we report a combined experimental and theoretical study on molecular structure and spectroscopic properties of the most stable conformers of PCA. 1 H, 13 C NMR and 2D COSY NMR, ESR, IR and electronic spectroscopies were coupled with DFT theoretical calculations performed at the B3LYP/6-31G** level. The calculated geometrical parameters for the neutral protocatechuic acid PCA-H 3 , its anions, its oxidized forms and the peroxo-derivative [PCA-H-O 2 ] 2- are in line with the experimental data. The neutral catecholate is the most stable form of PCA-H 3 whilst the dianion [PCA-H] 2- presents higher energy. This anion is (experimentally) stable only under argon, reacting with dioxygen, in the presence of air. The semiquinone [PCA-H-sq(3)] - is very close in energy from [PCA-H-sq(4)] - form and an equilibrium between these two oxidized radical forms might be expected. The energetically advantageous pathway for preparation of the symmetrically delocalized [PCA-sq] 2- is to oxidize the [PCA] 3- . The occurrence of this radical dianion form was justified experimentally by ESR, IR, UV-vis and NMR spectra. The structural calculations for [PCA-H-O 2 ] 2- indicate that C 3 (and to a lesser extent C1) may undergo a nucleophilic attack from the 'co-ordinated' peroxo-group. The conditions for the non-enzymatic degradation of PCA have been established and some new products are observed: ionization of PCA-H 3 , the presence of O 2 and aprotic solvents provide the semiquinone-superoxo adduct which is then degraded to lactones, while in protic solvents, addition of H 2 O 2 and the presence of air, are essential, providing aliphatic degradation products

  19. Poly(ethylene glycol) (PEG)-lactic acid nanocarrier-based degradable hydrogels for restoring the vaginal microenvironment

    Science.gov (United States)

    Rajan, Sujata Sundara; Turovskiy, Yevgeniy; Singh, Yashveer; Chikindas, Michael L.; Sinko, Patrick J.

    2014-01-01

    Women with bacterial vaginosis (BV) display reduced vaginal acidity, which make them susceptible to associated infections such as HIV. In the current study, poly(ethylene glycol) (PEG) nanocarrier-based degradable hydrogels were developed for the controlled release of lactic acid in the vagina of BV-infected women. PEG-lactic acid (PEG-LA) nanocarriers were prepared by covalently attaching lactic acid to 8-arm PEG-SH via cleavable thioester bonds. PEG-LA nanocarriers with 4 copies of lactic acid per molecule provided controlled release of lactic acid with a maximum release of 23% and 47% bound lactic acid in phosphate buffered saline (PBS, pH 7.4) and acetate buffer (AB, pH 4.3), respectively. The PEG nanocarrier-based hydrogels were formed by cross-linking the PEG-LA nanocarriers with 4-arm PEG-NHS via degradable thioester bonds. The nanocarrier-based hydrogels formed within 20 min under ambient conditions and exhibited an elastic modulus that was 100-fold higher than the viscous modulus. The nanocarrier-based degradable hydrogels provided controlled release of lactic acid for several hours; however, a maximum release of only 10%–14% bound lactic acid was observed possibly due to steric hindrance of the polymer chains in the cross-linked hydrogel. In contrast, hydrogels with passively entrapped lactic acid showed burst release with complete release within 30 min. Lactic acid showed antimicrobial activity against the primary BV pathogen Gardnerella vaginalis with a minimum inhibitory concentration (MIC) of 3.6 mg/ml. In addition, the hydrogels with passively entrapped lactic acid showed retained antimicrobial activity with complete inhibition G. vaginalis growth within 48 h. The results of the current study collectively demonstrate the potential of PEG nanocarrier-based hydrogels for vaginal administration of lactic acid for preventing and treating BV. PMID:25223229

  20. Kinetics of soybean oil epoxidation with peracetic acid formed in situ in the presence of an ion exchange resin: Pseudo-homogeneous model

    Directory of Open Access Journals (Sweden)

    Janković Milovan

    2017-01-01

    Full Text Available A kinetic model was proposed for the epoxidation of vegetable oils with peracetic acid formed in situ from acetic acid and hydrogen peroxide in the presence of an acidic ion exchange resin as a catalyst. The model is pseudo-homogeneous with respect to the catalyst. Besides the main reactions of peracetic acid and epoxy ring formation, the model takes into account the side reaction of epoxy ring opening with acetic acid. The partitioning of acetic acid and peracetic acid between the aqueous and organic phases and the change in the phases’ volumes during the process were considered. The temperature dependency of the apparent reaction rate coefficients is described by a reparameterized Arrhenius equation. The constants in the proposed model were estimated by fitting the experimental data obtained for the epoxidations of soybean oil conducted under defined reaction conditions. The highest epoxy yield of 87.73% was obtained at 338 K when the mole ratio of oil unsaturation:acetic acid:hydrogen peroxide was 1:0.5:1.35 and when the amount of the catalyst Amberlite IR-120H was 4.04 wt.% of oil. Compared to the other reported pseudo-homogeneous models, the model proposed in this study better correlates the change of double bond and epoxy group contents during the epoxidation process. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III45022

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

    Science.gov (United States)

    Copinet, Alain; Legin-Copinet, Estelle; Erre, Damien

    2009-01-01

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

  2. Uranium recovery and uranium remove from acid mine waters by ion exchange resin; Remocao e recuperacao de uranio de aguas acidas de mina com resina de troca ionica

    Energy Technology Data Exchange (ETDEWEB)

    Nascimento, Marcos R.L. [Comissao Nacional de Energia Nuclear (CNEN), Pocos de Caldas, MG (Brazil). Coordenacao do Laborarorio; Fatibello Filho, Orlando [Sao Carlos Univ., SP (Brazil). Dept. de Quimica

    1999-11-01

    Ion exchange using resins is one of few processes capable of reducing contaminants in effluents to very low levels according to environmental legislation. In this study the process was used to remove and recovery uranium from acid mine waters at Pocos de Caldas-MG Uranium Mining and Milling Plant. The presence of pyrite in the waste rock piles, resulting acid drainage with several pollutants. Including uranium ranging from 6 to 14 mg/l, as sulfate complex, that can be removed by an anionic exchanger. Studies of uranium sorption without treatment, and with lime pretreatment of water to precipitate the iron and recovery uranium as commercial product, are presented. Uranium elution was done with NaCl solutions. Saline concentration and retention time were the parameters studied. the uranium decontaminations level in the effluents from acid mine water was 94%. (author) 10 refs., 6 tabs., 3 figs.

  3. Degradation of lignosulfonic and tannic acids by ligninolytic soil fungi cultivated under icroaerobic conditions

    Directory of Open Access Journals (Sweden)

    Isis Serrano Silva

    2010-06-01

    Full Text Available Soil fungi were evaluated regarding their ability to degrade lignin-related compounds by producing the ligninolytic enzymes. Lignosulfonic and tannic acids were used as sole carbon sources during 30 days under microaerobic and very-low-oxygen conditions. The fungi produced lignin-peroxidase, manganese-peroxidase and laccase . Expressive degradations was observed by C18 reversed-phase HPLC, indicating the biodegradation potential of these fungi, showing more advantages than obligate anaerobes to decontaminate the environment when present naturally.Fungos isolados de solo foram avaliados quanto à habilidade em degradarem compostos derivados de lignina pela produção de enzimas ligninolíticas. Os ácidos lignosulfônicos e tânico foram usados separadamente como única fonte de carobono para cultivo dos fungos em 30 dias sob condições microaeróbias. Os fungos foram capazes de crescer e usar tais compostos como fonte de carbono e mostraram produção de lignina-peroxidase, manganês-peroxidase e lacase. Degradações expressivas dos ácidos lignosulfônico e tânico foram verificadas por Cromatografia Liquida de Alta Eficiência (CLAE, indicando grande potencial de uso em processos de biorremediação de macromoléculas aromáticas similares à lignina em ambientes naturais sob condições baixas de oxigenação.

  4. Protein degradation mechanisms modulate abscisic acid signaling and responses during abiotic stress.

    Science.gov (United States)

    Jurkiewicz, Pawel; Batoko, Henri

    2018-02-01

    Abiotic stresses such as salinity, drought, high temperature or freezing can be perceived, in part, as a transient or permanent hyperosmotic stress by the plant cell. As sessile organisms, the detrimental effects of these environmental insults limit plants productivity but also their geographical distribution. Sensing and signaling events that detect the hyperosmotic (or simply osmotic) stress involve the cellular increase of active abscisic acid (ABA). The stress phytohormone ABA regulates fundamental growth and developmental processes in the plant by marshalling metabolic and gene-expression reprogramming. Among the ABA-responsive genes, some are strictly ABA-dependent in that their expression is almost undetectable in absence of elevated levels of cellular ABA, thus their physiological role may be required only transiently. In addition, ABA-dependent modulation of some of the signaling effectors can be irreversible. In this review, without any pretention to being exhaustive, we use specific examples to illustrate how mechanistically conserved eukaryotic cell proteolytic pathways affect ABA-dependent signaling. We describe how defined proteolysis mechanisms in the plant cell, including Regulated Intramembrane Proteolysis (RIP), the Ubiquitin 26S Proteasomal System (UPS), the endocytic and autophagy pathways, contribute to regulate the spatiotemporal level and activity of PP2Cs (protein phosphatases 2C), and how an intriguing ABA-induced protein, the plant Translocator protein (TSPO), is targeted for degradation. Degradation of regulatory or effector molecules modulates or desensitizes ABA-dependent signaling and reestablishes cellular homeostasis. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Enzymatic and acidic degradation effect on intracellular polysaccharide of Flammulina velutipes SF-08.

    Science.gov (United States)

    Ma, Zhao; Zhang, Chen; Gao, Xia; Cui, Fangyuan; Zhang, Jianjun; Jia, Mengshi; Jia, Shouhua; Jia, Le

    2015-02-01

    The intracellular polysaccharide (IPS) from Flammulina velutipes SF-08 mycelia was isolated and degraded by enzyme and acid. IPS and its derivative were purified by DEAE-52 cellulose chromatography, and five fractions were obtained. The structural features and antioxidant activities in vitro of the isolated fractions were evaluated. On the basis of chemical composition and antioxidant ability analyses, rhamnose as the main monosaccharide might contribute to the strongest antioxidant capacity. The in vivo results showed that IPS significantly enhanced the activities of anti-aging enzymes, such as superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity, and reduced the content of lipid peroxidantion (LPO). These results suggested that IPS should be a potent natural polymer and can be developed to be novel functional food. Copyright © 2014 Elsevier B.V. All rights reserved.

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

    Directory of Open Access Journals (Sweden)

    B. Grabowska

    2010-01-01

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

  7. Effect of demineralization on the physiochemical structure and thermal degradation of acid treated indigenous rice husk

    Directory of Open Access Journals (Sweden)

    Aslam Umair

    2016-09-01

    Full Text Available Energy generation from biomass presents some serious problems like slagging, fouling and corrosion of boilers. To address these problems, demineralization of biomass is performed using different leaching agents. This study is focused on determining the influence of leaching agents and leaching time on the physiochemical structure of rice husk during demineralization. Dilute (5% wt solutions of HCl and H2SO4 were used for the demineralization of rice husk separately with leaching time of 15, 60 and 120 minutes. It is shown that H2SO4 exhibited higher removal of alkali and alkaline earth metals (AAEM comparatively as depicted by the 34.2% decrease in ash content along with an increase of 7.10% in the heating value. The acid has been seen to induce more notable changes in physiochemical structure as depicted by the FTIR spectra and SEM micrographs. The thermal degradation behavior of the demineralized rice husk has also been reported.

  8. Performance of Fluidized bed Fenton process in Degrading Acid Blue 113

    Science.gov (United States)

    Bello, M. M.; Raman, A. A.

    2017-06-01

    The performance of a fluidized bed Fenton process in degrading Acid Blue 113 (AB 113) was investigated. Fluidized bed Fenton process is a modification of conventional Fenton oxidation, aimed at reducing sludge generation and improving process performance. Response surface methodology was used to study the effects of operational parameter on the color removal from the dye. Dimensionless factors, Dye/Fe2+, H2O2/Fe2+ and pH were used as the independent variables in Box-Behnken Design (BDD). Reduced quadratic model was developed to predict the color removal. The process could remove up to 99 % of the initial color. The most significant factor for color removal was found to be Dye/Fe2+, followed by H2O2/Fe2+. Unlike conventional Fenton, the initial pH of the solution does not have a significant effect on the color removal.

  9. Acid-degradable Dextran as an Image Guided siRNA Carrier for COX-2 Downregulation.

    Science.gov (United States)

    Chen, Zhihang; Krishnamachary, Balaji; Penet, Marie-France; Bhujwalla, Zaver M

    2018-01-01

    Purpose: Effective in vivo delivery of siRNA to silence genes is a highly sought-after goal in the treatment of multiple diseases. Cyclooxygenase-2 (COX-2) is a major mediator of inflammation and its effective and specific downregulation has been of major interest to treat conditions ranging from auto-immune diseases to gastric inflammation and cancer. Here we developed a novel and efficient method to produce a multiple imaging reporter labeled cationic dextran nanopolymer with cleavable positive charge groups for COX-2 siRNA delivery. Methods: Small molecules containing amine groups were conjugated to the dextran scaffold through acetal bonds that were cleaved in weak acid conditions. With multiple imaging reporters located on different regions of the nanopolymer, cleavage of acetal bonds was visualized and quantified by imaging, for the first time, in cancer cells and tumors. Results: The biocompatibility of dextran and the rapid cleavage and release of amine groups minimized proinflammatory side effects and COX-2 induction observed with other siRNA carriers, to successfully achieve COX-2 downregulation in cancer cells and tumors. Imaging results confirmed that this nanoplex, consisting of the dextran nanopolymer with COX-2 siRNA, accumulated in tumors, and the amine functional groups were rapidly cleaved in cancer cells and tumors. Along with effective downregulation of COX-2, we also demonstrated, for the first time, effective downregulation of its major product prostaglandin E 2 (PGE 2 ). Conclusions: We successfully developed an efficient method to produce an acid-degradable dextran nanopolymer containing cleavable amine groups as the siRNA carrier. Because of its biocompatibility, this degradable dextran delivered COX-2 siRNA within tumors and efficiently downregulated COX-2 expression.

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

    Directory of Open Access Journals (Sweden)

    Pelletier Eric

    2010-10-01

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

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

    Science.gov (United States)

    Fonknechten, Nuria; Chaussonnerie, Sébastien; Tricot, Sabine; Lajus, Aurélie; Andreesen, Jan R; Perchat, Nadia; Pelletier, Eric; Gouyvenoux, Michel; Barbe, Valérie; Salanoubat, Marcel; Le Paslier, Denis; Weissenbach, Jean; Cohen, Georges N; Kreimeyer, Annett

    2010-10-11

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

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

    Science.gov (United States)

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

    2014-01-14

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

  13. Influence of fulvic acid and hydroxy propyl-beta-cyclodextrin on aspirin degradation.

    Science.gov (United States)

    Anwer, Mohammad Khalid; Agarwal, Suraj Prakash; Ali, Asgar; Sultana, Yasmin

    2010-04-01

    The degradation of aspirin (ASA) was investigated to reveal information about the influence of complexation with fulvic acid (FA), as a new complexing agent and compared with hydroxy propyl-beta-cyclodextrin complex. ASA was complexed with FA in the molar ratio 1:0.5, 1:1, and 1:2 by different methods through lyophilization, solvent evaporation, and spray drying. Spray-dried (1:1) ASA-hydroxy propyl-beta-cyclodextrin complex was prepared and compared with optimized complex of FA. All the complexes and ASA alone were packaged in well-labeled sealed polythene-lined aluminum pouches and stored in stability chamber at 40 +/- 2 degrees C and 75 +/- 5% relative humidity for 120 days. Samples were analyzed for salicylic acid content at 0, 30, 60, 90, and 120 days. Overall 4.31% salicylic acid was formed in 1:1 ASA-FA spray-dried complex, which was optimized stable complex among other complexes of FA prepared by different methods in different molar ratios. However, 2.35% salicylic acid was measured with 1:1 spray-dried ASA-hydroxy propyl-beta-cyclodextrin complex. Stability of ASA increased more when complexed with hydroxy propyl-beta-cyclodextrin as compared to FA. A novel complexing agent in the form of FA was investigated to increase the stability of ASA. A marked improvement in stability of ASA was observed when complexed with hydroxy propyl-beta-cyclodextrin (1:1) by spray drying as compared to 1:1 spray-dried ASA-FA complex.

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

    Science.gov (United States)

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

    2016-01-01

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

  15. Agdc1p – a Gallic Acid Decarboxylase Involved in the Degradation of Tannic Acid in the Yeast Blastobotrys (Arxula adeninivorans

    Directory of Open Access Journals (Sweden)

    Anna K. Meier

    2017-09-01

    Full Text Available Tannins and hydroxylated aromatic acids, such as gallic acid (3,4,5-trihydroxybenzoic acid, are plant secondary metabolites which protect plants against herbivores and plant-associated microorganisms. Some microbes, such as the yeast Arxula adeninivorans are resistant to these antimicrobial substances and are able to use tannins and gallic acid as carbon sources. In this study, the Arxula gallic acid decarboxylase (Agdc1p which degrades gallic acid to pyrogallol was characterized and its function in tannin catabolism analyzed. The enzyme has a higher affinity for gallic acid (Km −0.7 ± 0.2 mM, kcat −42.0 ± 8.2 s−1 than to protocatechuic acid (3,4-dihydroxybenzoic acid (Km −3.2 ± 0.2 mM, kcat −44.0 ± 3.2 s−1. Other hydroxylated aromatic acids, such as 3-hydroxybenzoic acid, 4-hydroxybenzoic acid, 2,3-dihydroxybenzoic acid, 2,4-dihydroxybenzoic acid and 2,5-dihydroxybenzoic acid are not gallic acid decarboxylase substrates. A. adeninivorans G1212/YRC102-AYNI1-AGDC1, which expresses the AGDC1 gene under the control of the strong nitrate inducible AYNI1 promoter achieved a maximum gallic acid decarboxylase activity of 1064.4 U/l and 97.5 U/g of dry cell weight in yeast grown in minimal medium with nitrate as nitrogen source and glucose as carbon source. In the same medium, gallic acid decarboxylase activity was not detected for the control strain G1212/YRC102 with AGDC1 expression under the control of the endogenous promoter. Gene expression analysis showed that AGDC1 is induced by gallic acid and protocatechuic acid. In contrast to G1212/YRC102-AYNI1-AGDC1 and G1212/YRC102, A. adeninivorans G1234 [Δagdc1] is not able to grow on medium with gallic acid as carbon source but can grow in presence of protocatechuic acid. This confirms that Agdc1p plays an essential role in the tannic acid catabolism and could be useful in the production of catechol and cis,cis-muconic acid. However, the protocatechuic acid catabolism via Agdc1p to

  16. Reaction catalysts of urea-formaldehyde resin, as related to strength properties of southern pine particleboard

    Science.gov (United States)

    C. -Y. Hse

    1974-01-01

    Twelve resins were formulated with factorial combinations of three alkaline catalysts (i.e., somdium hydroxide, hexamethylenetetramine, and triethanolamine) and four acidic catalysts (i.e., acetic acid, hydrochloric acid, ammonium chloride, and phosphoric acid). The resins were replicated.

  17. Reaction pathway of the degradation of the p-hydroxybenzoic acid by sulfate radical generated by ionizing radiations

    International Nuclear Information System (INIS)

    Criquet, Justine; Leitner, Nathalie Karpel Vel

    2015-01-01

    The degradation of p-hydroxybenzoic acid (HBA) in aqueous solutions by ionizing radiation was studied. The phenolic pollutant was easily removed by the electron beam irradiation, as more than 80% of the initial 100 µM introduced was degraded for a dose of 600 Gy. It was shown that the addition of persulfate, producing the sulfate radical as additional reactive species, induced a change in the reaction pathway. LC–MS analyses were performed in order to identify the different by-products formed. In the absence of persulfate, the main by-product formed was 3,4-dihydroxybenzoic acid, while in presence of persulfate, 1,4-benzoquinone was detected and the hydroxylated by-products were not present. A reaction pathway of HBA degradation by hydroxyl and sulfate radicals was proposed from the identification of the chemical structure of the different by-products detected. The influences of pH and dissolved oxygen were also studied. A high decline of HBA degradation was observed at pH 11 compared to pH 4.5, this decrease was minimized in the presence of persulfate. The dissolved oxygen concentration was found to be a limiting parameter of HBA degradation, however an excess of dissolved oxygen in solution did not improve the degradation to a large extent. - Highlights: • p-Hydroxybenzoic acid (HBA) is easily removed by e-beam irradiation. • The sulfate radicals formed from persulfate induce loss of the benzoic acid skeleton. • The dissolved oxygen concentration is a limiting parameter of the HBA degradation. • The effect of pH is minimized in presence of persulfate

  18. Identification of the Acid-Induced Degradation Products of Omeprazole and 5-hydroxyomeprazole by High Resolution Mass Spectrometry.

    Science.gov (United States)

    Roberts, J; McNaughtan, M; MacLachlan, J; Hunter, C; Pahl, O

    2018-03-23

    Omeprazole is used to treat gastric disorders and is one of the most commonly consumed drugs in the western world. It forms several metabolites but is mostly excreted unchanged and as 5-hydroxyomeprazole. Since omeprazole is widely prescribed, its excretion from the body has a potential environmental effect. After excretion it will enter the wastewater system and if not adequately removed during wastewater treatment will be discharged into rivers in the wastewater effluent. It is important to consider not only the parent drug but also the main metabolite (5-hydroxyomeprazole) and their degradation products to fully understand the fate of this drug during wastewater treatment. In order to do this potential degradation products need to be determined. Acid was used to artificially accelerate the degradation of omeprazole and 5-hydroxyomeprazole. A Q-Exactive Orbitrap mass spectrometer with an electrospray ion source was used to determine precursor and product ion data for the degradation products. Both starting materials quickly degrade under acidic conditions and the main degradation product formed in each case was a re-arranged monomer. Other species identified were doubly and singly charged dimers with varying numbers of sulphur atoms in the dimer bridge. Careful interpretation of the accurate mass, isotope pattern, isotope abundance and product ion spectra was used to interpret the data. The resultant degradants from omeprazole and 5-hydroxyomeprazole were analogous to each other, differing only by an oxygen atom. This investigation determined the degradation products of omeprazole and 5-hydroxyomeprazole and proposed structures based on the accurate mass and isotope information. The product ions from the degradation products are also reported. This article is protected by copyright. All rights reserved.

  19. Floating Photocatalysts for Passive Solar Degradation of Naphthenic Acids in Oil Sands Process-Affected Water

    Directory of Open Access Journals (Sweden)

    Tim Leshuk

    2018-02-01

    Full Text Available Oil sands process-affected water (OSPW, generated from bitumen extraction in the Canadian oil sands, may require treatment to enable safe discharge to receiving watersheds, as dissolved naphthenic acids (NAs and other acid extractable organics (AEO, identified as the primary toxic components of OSPW, are environmentally persistent and poorly biodegradable. However, conventional advanced oxidation processes (AOPs are impractically expensive to treat the volumes of OSPW stockpiled in the Athabasca region. Here we prepared floating photocatalysts (FPCs by immobilizing TiO2 on glass microbubbles, such that the composite particles float at the air-water interface for passive solar photocatalysis. The FPCs were demonstrated to outperform P25 TiO2 nanoparticles in degrading AEO in raw OSPW under natural sunlight and gentle mixing conditions. The FPCs were also found to be recyclable for multiple uses through simple flotation and skimming. This paper thus demonstrates the concept of a fully passive AOP that may be scalable to oil sands water treatment challenges, achieving efficient NA reduction solely through the energy provided by sunlight and natural mixing processes (wind and waves.

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

    Directory of Open Access Journals (Sweden)

    Fátima Duarte Freire

    2014-12-01

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

  1. Natural formation and degradation of chloroacetic acids and volatile organochlorines in forest soil--challenges to understanding.

    Science.gov (United States)

    Laturnus, Frank; Fahimi, Isabelle; Gryndler, Milan; Hartmann, Anton; Heal, Mathew R; Matucha, Miroslav; Schöler, Heinz Friedrich; Schroll, Reiner; Svensson, Teresia

    2005-07-01

    The anthropogenic environmental emissions of chloroacetic acids and volatile organochlorines have been under scrutiny in recent years because the two compound groups are suspected to contribute to forest dieback and stratospheric ozone destruction, respectively. The two organochlorine groups are linked because the atmospheric photochemical oxidation of some volatile organochlorine compounds is one source of phytotoxic chloroacetic acids in the environment. Moreover, both groups are produced in higher amounts by natural chlorination of organic matter, e.g. by soil microorganisms, marine macroalgae and salt lake bacteria, and show similar metabolism pathways. Elucidating the origin and fate of these organohalogens is necessary to implement actions to counteract environmental problems caused by these compounds. While the anthropogenic sources of chloroacetic acids and volatile organochlorines are relatively well-known and within human control, knowledge of relevant natural processes is scarce and fragmented. This article reviews current knowledge on natural formation and degradation processes of chloroacetic acids and volatile organochlorines in forest soils, with particular emphasis on processes in the rhizosphere, and discusses future studies necessary to understand the role of forest soils in the formation and degradation of these compounds. Reviewing the present knowledge of the natural formation and degradation processes of chloroacetic acids and volatile organochlorines in forest soil has revealed gaps in knowledge regarding the actual mechanisms behind these processes. In particular, there remains insufficient quantification of reliable budgets and rates of formation and degradation of chloroacetic acids and volatile organochlorines in forest soil (both biotic and abiotic processes) to evaluate the strength of forest ecosystems regarding the emission and uptake of chloroacetic acids and volatile organochlorines, both on a regional scale and on a global scale

  2. Characterization and Genome Analysis of a Nicotine and Nicotinic Acid-Degrading Strain Pseudomonas putida JQ581 Isolated from Marine.

    Science.gov (United States)

    Li, Aiwen; Qiu, Jiguo; Chen, Dongzhi; Ye, Jiexu; Wang, Yuhong; Tong, Lu; Jiang, Jiandong; Chen, Jianmeng

    2017-05-31

    The presence of nicotine and nicotinic acid (NA) in the marine environment has caused great harm to human health and the natural environment. Therefore, there is an urgent need to use efficient and economical methods to remove such pollutants from the environment. In this study, a nicotine and NA-degrading bacterium-strain JQ581-was isolated from sediment from the East China Sea and identified as a member of Pseudomonas putida based on morphology, physio-biochemical characteristics, and 16S rDNA gene analysis. The relationship between growth and nicotine/NA degradation suggested that strain JQ581 was a good candidate for applications in the bioaugmentation treatment of nicotine/NA contamination. The degradation intermediates of nicotine are pseudooxynicotine (PN) and 3-succinoyl-pyridine (SP) based on UV, high performance liquid chromatography, and liquid chromatography-mass spectrometry analyses. However, 6-hydroxy-3-succinoyl-pyridine (HSP) was not detected. NA degradation intermediates were identified as 6-hydroxynicotinic acid (6HNA). The whole genome of strain JQ581 was sequenced and analyzed. Genome sequence analysis revealed that strain JQ581 contained the gene clusters for nicotine and NA degradation. This is the first report where a marine-derived Pseudomonas strain had the ability to degrade nicotine and NA simultaneously.

  3. Efficient photocatalytic degradation of perfluorooctanoic acid by a wide band gap p-block metal oxyhydroxide InOOH

    Science.gov (United States)

    Xu, Jingjing; Wu, Miaomiao; Yang, Jingwen; Wang, Zhengmei; Chen, Mindong; Teng, Fei

    2017-09-01

    In this work, we prepared a new wide band gap semiconductor, p-block metal oxyhydroxide InOOH, which exhibits efficient activity for perfluorooctanoic acid (PFOA) degradation under mild conditions and UV light irradiation. The apparent rate constant for PFOA degradation by InOOH is 27.6 times higher than that for P25 titania. Results show that ionized PFOA (C7F15COO-) can be adsorbed much more efficiently on the surface of InOOH than P25. Then, the adsorbed C7F15COO- can be decomposed directly by photo-generated holes to form C7F15COOrad radicals. This process is the key step for the photocalytic degradation of PFOA. Major degradation intermediates, fluoride ions and perfluorinated carboxylic acids (PFCAs) with shorter chain lengths were detected during PFOA degradation. A possible pathway for photocatalytic degradation of PFOA is proposed based on the experimental results. Therefore, this studies indicates a potential new material and method for the efficient treatment of PFCA pollutants under mild conditions.

  4. Di-D-fructose dianhydride-enriched products by acid ion-exchange resin-promoted caramelization of D-fructose: chemical analyses.

    Science.gov (United States)

    Suárez-Pereira, Elena; Rubio, Enrique M; Pilard, Serge; Ortiz Mellet, Carmen; García Fernández, José M

    2010-02-10

    Caramelization commonly occurs when sugars, or products containing a high proportion of sugars, are heated either dry or in concentrated aqueous solutions, alone or in the presence of certain additives. Upon thermal treatment of sugars, dehydration and self-condensation reactions occur, giving rise to volatiles (principally 2-hydroxymethylfurfural, HMF), pigments (melanoidines) and oligosaccharidic material, among which di-D-fructose dianhydrides (DFAs) and glycosylated DFA derivatives of different degree of polymerization (DP) have been identified. This study reports a methodology to produce caramel-like products with a high content of DFAs and oligosaccharides thereof from commercial D-fructose based on the use of acid ion-exchange resins as caramelization promotors. The rate of formation of these compounds as a function of D-fructose concentration, catalyst proportion, temperature, catalyst nature and particle size has been investigated. The use of sulfonic acid resins allows conducting caramelization at remarkable low temperatures (70-90 degrees C) to reach conversions into DFA derivatives up to 70-80% in 1-2 h, with relative proportions of HMF < 2%.The relative abundance of individual DFA structures can be modulated by acting on the catalyst nature and reaction conditions, which offers a unique opportunity for nutritional studies of DFA-enriched products with well-defined compositions.

  5. EDF specifications on nuclear grade resins

    International Nuclear Information System (INIS)

    Mascarenhas, Darren; Gressier, Frederic; Taunier, Stephane; Le-Calvar, Marc; Ranchoux, Gilles; Marteau, Herve; Labed, Veronique

    2012-09-01

    Ion exchange resins are widely used across EDF, especially within the nuclear division for the purification of water. Important applications include primary circuit, secondary circuit and effluent treatment, which require high quality nuclear grade resins to retain the dissolved species, some of which may be radioactive. There is a need for more and more efficient purification in order to decrease worker dose during maintenance but also to decrease volumes of radioactive resin waste. Resin performance is subject to several forms of degradation, including physical, chemical, thermal and radioactive, therefore appropriate resin properties have to be selected to reduce such effects. Work has been done with research institutes, manufacturers and on EDF sites to select these properties, create specifications and to continuously improve on these specifications. An interesting example of research regarding resin performance is the resin degradation under irradiation. Resins used in the CVCS circuit of EDF nuclear power plants are subject to irradiation over their lifetime. A study was carried out on the effects of total integrated doses of 0.1, 1 and 10 MGy on typically used EDF mixed bed resins in a 'mini-CVCS' apparatus to simultaneously test actual primary circuit fluid. The tests confirmed that the resins still perform efficiently after a typical CVCS radiation dose. Certain resins also need additional specifications in order to maintain the integrity of the particular circuits they are used in. Recently, EDF has updated its requirements on these high purity nuclear grade resins, produced generic doctrines for all products and materials used on site which include resins of all grades, and as a result have also updated a guide on recommended resin usage for the French fleet of reactors. An overview of the evolutions will be presented. (authors)

  6. Mechanism of azo dye degradation in Advanced Oxidation Processes: Degradation of Sulfanilic Acid Azochromotrop and its parent compounds in aqueous solution by ionizing radiation

    International Nuclear Information System (INIS)

    Palfi, Tamas; Wojnarovits, Laszlo; Takacs, Erzsebet

    2011-01-01

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

  7. Thermal properties of extruded injection-molded poly (lactic acid) and milkweed composites: degradation kinetics and enthalpic relaxation

    Science.gov (United States)

    Currently, most polymer composites utilize petroleum-based materials that are non-degradable and difficult to recycle or incur substantial cost for disposal. Green composites can be used in nondurable limited applications. In order to determine the degree of compatibility between Poly (lactic Acid...

  8. A comparison of anaerobic 2, 4-dichlorophenoxy acetic acid degradation in single-fed and sequencing batch reactor systems

    Science.gov (United States)

    Elefsiniotis, P.; Wareham, D. G.; Fongsatitukul, P.

    2017-08-01

    This paper compares the practical limits of 2, 4-dichlorophenoxy acetic acid (2,4-D) degradation that can be obtained in two laboratory-scale anaerobic digestion systems; namely, a sequencing batch reactor (SBR) and a single-fed batch reactor (SFBR) system. The comparison involved synthesizing a decade of research conducted by the lead author and drawing summative conclusions about the ability of each system to accommodate industrial-strength concentrations of 2,4-D. In the main, 2 L liquid volume anaerobic SBRs were used with glucose as a supplemental carbon source for both acid-phase and two-phase conditions. Volatile fatty acids however were used as a supplemental carbon source for the methanogenic SBRs. The anaerobic SBRs were operated at an hydraulic retention time of 48 hours, while being subjected to increasing concentrations of 2,4-D. The SBRs were able to degrade between 130 and 180 mg/L of 2,4-D depending upon whether they were operated in the acid-phase or two-phase regime. The methanogenic-only phase did not achieve 2,4-D degradation however this was primarily attributed to difficulties with obtaining a sufficiently long SRT. For the two-phase SFBR system, 3.5 L liquid-volume digesters were used and no difficulty was experienced with degrading 100 % of the 2,4-D concentration applied (300 mg/L).

  9. Oxidative degradation of acid doped polybenzimidazole membranes and fuel cell durability in the presence of ferrous ions

    DEFF Research Database (Denmark)

    Liao, Jianhui; Yang, Jingshuai; Li, Qingfeng

    2013-01-01

    Phosphoric acid doped polybenzimidazole membranes have been explored as proton exchange membranes for high temperature polymer electrolyte membrane fuel cells. Long-term durability of the membrane is of critical concern and has been evaluated by accelerated degradation tests under Fenton conditio...

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

    Science.gov (United States)

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

    2015-11-17

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

  11. Effect of acid on the photocatalytic degradation of rhodamine B over g-C{sub 3}N{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Shun; Lv, Kangle, E-mail: lvkangle@mail.scuec.edu.cn; Li, Qin; Ye, Hengpeng; Du, Dongyun; Li, Mei, E-mail: limei@mail.scuec.edu.cn

    2015-12-15

    Graphical abstract: Comparison of the degradation mechanisms of RhB over g-C3N4 in the absence (a) and presence (b) of acid. - Highlights: • Degradation of RhB over g-C{sub 3}N{sub 4} was greatly enhanced in the presence of acid. • O{sub 2}·{sup −} is the predominant ROSs responsible for the efficient degradation of RhB. • Acidification of g-C{sub 3}N{sub 4} results in the formation of a new surface state. • The formed surface state acts as a trapping site for photo-generated electrons. - Abstract: Low quantum efficiency has hampered the practical application of graphitic carbon nitride (g-C{sub 3}N{sub 4}). In this study, the effect of acid (H{sub 2}SO{sub 4} and HF) on the photocatalytic degradation of Rhodamine B (RhB) over g-C{sub 3}N{sub 4} was studied. It was found that the degradation of RhB was greatly enhanced in the presence of acid, and superoxide (O{sub 2}·{sup −}) is the predominant reactive oxygen species (ROSs) that are responsible for the efficient degradation of RhB. It is proposed that acidification of g-C{sub 3}N{sub 4} results in the formation of a new surface state, which is 0.3 eV below the conduction band position of g-C{sub 3}N{sub 4}. The formed surface state can act as a trapping site for photo-generated electrons, which retards the recombination of the electron–hole pairs, enhancing the photocatalytic activity of g-C{sub 3}N{sub 4}.

  12. Quantification of ascorbic acid and acetylsalicylic acid in effervescent tablets by CZE-UV and identification of related degradation products by heart-cut CZE-CZE-MS.

    Science.gov (United States)

    Neuberger, Sabine; Jooß, Kevin; Ressel, Christian; Neusüß, Christian

    2016-12-01

    Capillary electrophoresis is commonly applied for the analysis of pharmaceutical products due to its high separation efficiency and selectivity. For this purpose, electrospray-ionization-(ESI)-interfering additives or electrolytes are often required, which complicates the identification of impurities and degradation products by mass spectrometry (MS). Here, a capillary zone electrophoresis (CZE) method with ultraviolet (UV) absorption detection for the simultaneous determination and quantification of ascorbic acid and acetylsalicylic acid in effervescent tablets was developed. Related degradation products were identified via CZE-CZE-MS. Systematic optimization yielded 100 mM tricine (pH = 8.8) as appropriate background electrolyte, resulting in baseline separation of ascorbic acid, acetylsalicylic acid, and related anionic UV-active degradation products. The CZE-UV method was successfully validated regarding the guidelines of the Food and Drug Administration. The validated method was applied to trace the degradation rate of the active pharmaceutical ingredients at defined ambient conditions. A heart-cut CZE-CZE-MS approach, including a 4-port-nL-valve, was performed for the identification of the observed degradation products. This 2D setup enables a precise cutting of accurate sample volumes (20 nL) and the independent operation of two physically separated CZE dimensions, which is especially beneficial regarding MS detection. Hence, the ESI-interfering tricine electrolyte components were separated from the analytes in a second electrophoretic dimension prior to ESI-MS detection. The degradation products were identified as salicylic acid and mono- and diacetylated ascorbic acid. This setup is expected to be generally applicable for the mass spectrometric characterization of CZE separated analytes in highly ESI-interfering electrolyte systems. Graphical Abstract A CZE-UV method for the quantification of effervescent tablet ingredients and degradation products

  13. Evolution of Diterpene Metabolism: Sitka Spruce CYP720B4 Catalyzes Multiple Oxidations in Resin Acid Biosynthesis of Conifer Defense against Insects1[C][W][OA

    Science.gov (United States)

    Hamberger, Björn; Ohnishi, Toshiyuki; Hamberger, Britta; Séguin, Armand; Bohlmann, Jörg

    2011-01-01

    Diterpene resin acids (DRAs) are specialized (secondary) metabolites of the oleoresin defense of conifers produced by diterpene synthases and cytochrome P450s of the CYP720B family. The evolution of DRA metabolism shares common origins with the biosynthesis of ent-kaurenoic acid, which is highly conserved in general (primary) metabolism of gibberellin biosynthesis. Transcriptome mining in species of spruce (Picea) and pine (Pinus) revealed CYP720Bs of four distinct clades. We cloned a comprehensive set of 12 different Sitka spruce (Picea sitchensis) CYP720Bs as full-length cDNAs. Spatial expression profiles, methyl jasmonate induction, and transcript enrichment in terpenoid-producing resin ducts suggested a role of CYP720B4 in DRA biosynthesis. CYP720B4 was characterized as a multisubstrate, multifunctional enzyme by the formation of oxygenated diterpenoids in metabolically engineered yeast, yeast in vivo transformation of diterpene substrates, in vitro assays with CYP720B4 protein produced in Escherichia coli, and alteration of DRA profiles in RNA interference-suppressed spruce seedlings. CYP720B4 was active with 24 different diterpenoid substrates, catalyzing consecutive C-18 oxidations in the biosynthesis of an array of diterpene alcohols, aldehydes, and acids. CYP720B4 was most active in the formation of dehydroabietic acid, a compound associated with insect resistance of Sitka spruce. We identified patterns of convergent evolution of CYP720B4 in DRA metabolism and ent-kaurene oxidase CYP701 in gibberellin metabolism and revealed differences in the evolution of specialized and general diterpene metabolism in a gymnosperm. The genomic and functional characterization of the gymnosperm CYP720B family highlights that the evolution of specialized metabolism involves substantial diversification relative to conserved, general metabolism. PMID:21994349

  14. Evolution of diterpene metabolism: Sitka spruce CYP720B4 catalyzes multiple oxidations in resin acid biosynthesis of conifer defense against insects.

    Science.gov (United States)

    Hamberger, Björn; Ohnishi, Toshiyuki; Hamberger, Britta; Séguin, Armand; Bohlmann, Jörg

    2011-12-01

    Diterpene resin acids (DRAs) are specialized (secondary) metabolites of the oleoresin defense of conifers produced by diterpene synthases and cytochrome P450s of the CYP720B family. The evolution of DRA metabolism shares common origins with the biosynthesis of ent-kaurenoic acid, which is highly conserved in general (primary) metabolism of gibberellin biosynthesis. Transcriptome mining in species of spruce (Picea) and pine (Pinus) revealed CYP720Bs of four distinct clades. We cloned a comprehensive set of 12 different Sitka spruce (Picea sitchensis) CYP720Bs as full-length cDNAs. Spatial expression profiles, methyl jasmonate induction, and transcript enrichment in terpenoid-producing resin ducts suggested a role of CYP720B4 in DRA biosynthesis. CYP720B4 was characterized as a multisubstrate, multifunctional enzyme by the formation of oxygenated diterpenoids in metabolically engineered yeast, yeast in vivo transformation of diterpene substrates, in vitro assays with CYP720B4 protein produced in Escherichia coli, and alteration of DRA profiles in RNA interference-suppressed spruce seedlings. CYP720B4 was active with 24 different diterpenoid substrates, catalyzing consecutive C-18 oxidations in the biosynthesis of an array of diterpene alcohols, aldehydes, and acids. CYP720B4 was most active in the formation of dehydroabietic acid, a compound associated with insect resistance of Sitka spruce. We identified patterns of convergent evolution of CYP720B4 in DRA metabolism and ent-kaurene oxidase CYP701 in gibberellin metabolism and revealed differences in the evolution of specialized and general diterpene metabolism in a gymnosperm. The genomic and functional characterization of the gymnosperm CYP720B family highlights that the evolution of specialized metabolism involves substantial diversification relative to conserved, general metabolism.

  15. Modularity of Conifer Diterpene Resin Acid Biosynthesis: P450 Enzymes of Different CYP720B Clades Use Alternative Substrates and Converge on the Same Products.

    Science.gov (United States)

    Geisler, Katrin; Jensen, Niels Berg; Yuen, Macaire M S; Madilao, Lina; Bohlmann, Jörg

    2016-05-01

    Cytochrome P450 enzymes of the CYP720B subfamily play a central role in the biosynthesis of diterpene resin acids (DRAs), which are a major component of the conifer oleoresin defense system. CYP720Bs exist in families of up to a dozen different members in conifer genomes and fall into four different clades (I-IV). Only two CYP720B members, loblolly pine (Pinus taeda) PtCYP720B1 and Sitka spruce (Picea sitchensis) PsCYP720B4, have been characterized previously. Both are multisubstrate and multifunctional clade III enzymes, which catalyze consecutive three-step oxidations in the conversion of diterpene olefins to DRAs. These reactions resemble the sequential diterpene oxidations affording ent-kaurenoic acid from ent-kaurene in gibberellin biosynthesis. Here, we functionally characterized the CYP720B clade I enzymes CYP720B2 and CYP720B12 in three different conifer species, Sitka spruce, lodgepole pine (Pinus contorta), and jack pine (Pinus banksiana), and compared their activities with those of the clade III enzymes CYP720B1 and CYP720B4 of the same species. Unlike the clade III enzymes, clade I enzymes were ultimately found not to be active with diterpene olefins but converted the recently discovered, unstable diterpene synthase product 13-hydroxy-8(14)-abietene. Through alternative routes, CYP720B enzymes of both clades produce some of the same profiles of conifer oleoresin DRAs (abietic acid, neoabietic acid, levopimaric acid, and palustric acid), while clade III enzymes also function in the formation of pimaric acid, isopimaric acid, and sandaracopimaric acid. These results highlight the modularity of the specialized (i.e. secondary) diterpene metabolism, which produces conifer defense metabolites through variable combinations of different diterpene synthase and CYP720B enzymes. © 2016 American Society of Plant Biologists. All Rights Reserved.

  16. Degradation of protein translation machinery by amino acid starvation-induced macroautophagy

    DEFF Research Database (Denmark)

    Gretzmeier, Christine; Eiselein, Sven; Johnson, Gregory R.

    2017-01-01

    Macroautophagy is regarded as a nonspecific bulk degradation process of cytoplasmic material within the lysosome. However, the process has mainly been studied by nonspecific bulk degradation assays using radiolabeling. In the present study we monitor protein turnover and degradation by global, un...

  17. Investigation of the degradation and stability of acrylamide-based polymers in acid solution: Functional monomer modified polyacrylamide

    Directory of Open Access Journals (Sweden)

    Yuxin Pei

    2016-12-01

    Full Text Available Acrylamide copolymers are often used as acidizing diverting and thickening agents for their advantageous thickening, flocculation, adhesion and resistance reduction properties. Experimental results indicate that the acid concentration greatly affects the properties of acrylamide polymers, which varies from results reported by other researchers. Considering the theoretical and field application value of the present study, four comparable acrylamide-based polymers were synthesized, and their macro- and micro-changes as well as the related changes in viscosity and molecular weight were studied in high-concentration hydrochloric acid. A proposed mechanism of acrylamide copolymer stability and degradation is provided, and further suggestions are made for the modification of acrylamide copolymers.

  18. Methyl phosphate formation as a major degradation mode of direct methanol fuel cells with phosphoric acid based electrolytes

    DEFF Research Database (Denmark)

    Aili, David; Vassiliev, Anton; Jensen, Jens Oluf

    2015-01-01

    Phosphoric acid and phosphoric acid doped polymer membranes are widely used as electrolytes in hydrogen based fuel cells operating at elevated temperatures. Such electrolytes have been explored for direct oxidation of methanol to further increase the versatility of the systems, however......, with demonstrated lifetimes of only a few days to weeks. In this work the methyl phosphate formation from the acid and methanol is identified and proposed to be a major mechanism for the cell degradation. Proton conductivity and fuel cell durability tests validate the mechanism at high methanol contents....

  19. Removal of CdTe in acidic media by magnetic ion-exchange resin: A potential recycling methodology for cadmium telluride photovoltaic waste

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Teng, E-mail: zhangteng@mail.iee.ac.cn; Dong, Zebin; Qu, Fei; Ding, Fazhu; Peng, Xingyu; Wang, Hongyan; Gu, Hongwei

    2014-08-30

    Highlights: • Sulfonated magnetic microsphere was prepared as one strong acid cation-exchange resin. • Cd and Te can be removed directly from the highly acidic leaching solution of CdTe. • Good chemical stability, fast adsorbing rate and quick magnetic separation in strong acidic media. • A potential path for recycling CdTe photovoltaic waste. - Abstract: Sulfonated magnetic microspheres (PSt-DVB-SNa MPs) have been successfully prepared as adsorbents via an aqueous suspension polymerization of styrene-divinylbenzene and a sulfonation reaction successively. The resulting adsorbents were confirmed by means of Fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope equipped with an energy dispersive spectrometer (SEM-EDS) and vibrating sample magnetometer (VSM). The leaching process of CdTe was optimized, and the removal efficiency of Cd and Te from the leaching solution was investigated. The adsorbents could directly remove all cations of Cd and Te from a highly acidic leaching solution of CdTe. The adsorption process for Cd and Te reached equilibrium in a few minutes and this process highly depended on the dosage of adsorbents and the affinity of sulfonate groups with cations. Because of its good adsorption capacity in strong acidic media, high adsorbing rate, and efficient magnetic separation from the solution, PSt-DVB-SNa MPs is expected to be an ideal material for the recycling of CdTe photovoltaic waste.

  20. Effect of sodium hypochlorite and peracetic acid on the surface roughness of acrylic resin polymerized by heated water for short and long cycles.

    Science.gov (United States)

    Sczepanski, Felipe; Sczepanski, Claudia Roberta Brunnquell; Berger, Sandrine Bittencourt; Consani, Rafael Leonardo Xediek; Gonini-Júnior, Alcides; Guiraldo, Ricardo Danil

    2014-10-01

    To evaluate the surface roughness of acrylic resin submitted to chemical disinfection via 1% sodium hypochlorite (NaClO) or 1% peracetic acid (C2H4O3). The disc-shaped resin specimens (30 mm diameter ×4 mm height) were polymerized by heated water using two cycles (short cycle: 1 h at 74°C and 30 min at 100°C; conventional long cycle: 9 h at 74°C). The release of substances by these specimens in water solution was also quantified. Specimens were fabricated, divided into four groups (n = 10) depending on the polymerization time and disinfectant. After polishing, the specimens were stored in distilled deionized water. Specimens were immersed in 1% NaClO or 1% C2H4O3 for 30 min, and then were immersed in distilled deionized water for 20 min. The release of C2H4O3 and NaClO was measured via visual colorimetric analysis. Roughness was measured before and after disinfection. Roughness data were subjected to two-way ANOVA and Tukey's test. There was no interaction between polymerization time and disinfectant in influencing the average surface roughness (Ra, P = 0.957). Considering these factors independently, there were significant differences between short and conventional long cycles (P = 0.012), but no significant difference between the disinfectants hypochlorite and C2H4O3 (P = 0.366). Visual colorimetric analysis did not detect release of substances. It was concluded that there was the difference in surface roughness between short and conventional long cycles, and disinfection at acrylic resins polymerized by heated water using a short cycle modified the properties of roughness.

  1. Protein a resin lifetime study: Evaluation of protein a resin performance with a model-based approach in continuous capture.

    Science.gov (United States)

    Behere, Ketki; Cha, Bumjoon; Yoon, Seongkyu

    2018-01-22

    A modified shrinking core model (MSCM) has been used to describe the mechanism for the degradation of Protein A resin particles taking place under continuous chromatographic operation. The model is based on the hypothetical shrinkage of the boundary layer of the resin particles, which house the active Protein A ligands within their pores. The caustic during the sanitization phase of chromatography has been determined to cause the Protein A ligand degradation. Protein A resins provided by manufacturers possess unique caustic stability, which has been used in MSCM to appraise the ligand degradation. The kinetic model utilized semiempirical parameters including diffusion constant, rate constant, stoichiometric factor, and reaction order. The parameters were estimated from column breakthrough experiments to simulate continuous Protein A chromatography for three distinct resins. The reaction order has been identified as the key parameter for predicting the degradation kinetics. The recorded reaction orders vary for three different resins with the resin B showing the highest reaction order of 4 and lowest being 1.65 for the resin C. The model can predict the effects of caustic on resin performance and displayed that minimal degradation of the resins A and B occurred, when exposed to 0.1 N and 0.2N NaOH, retaining up to 96% binding capacity after 240 cycles. The adsorption study conducted for the resin B demonstrated the dynamic physical and chemical changes transpiring through the life cycle of the resin, further supported the degradation model. The performance data demonstrate that the resin B exhibits the desirable performance, with higher reaction order indicating slower resin degradation, higher binding capacities, and increased sustenance of this binding capacity for extended duration. The degradation model can be extended to build effective cleaning strategies for continuous downstream processing.

  2. Exposure of Atlantic salmon parr (Salmo salar) to a combination of resin acids and a water soluble fraction of diesel fuel oil: A model to investigate the chemical causes of pigmented salmon syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Croce, B. [Scottish Office Agriculture, Environment, and Fisheries Dept., Aberdeen (United Kingdom). Marine Lab.]|[Scottish Environmental Protection Agency, Aberdeen (United Kingdom). North East River Purification Board; Stagg, R.M. [Scottish Office Agriculture, Environment, and Fisheries Dept., Aberdeen (United Kingdom). Marine Lab.

    1997-09-01

    Pigmented salmon syndrome is a pollutant-induced hemolytic anemia and hyperbilirubinemia. As part of an investigation of this condition, S2 Atlantic salmon parr (Salmo salar) were exposed to a diesel fuel oil, water soluble fraction (WSF) in combination with a mixture of three resin acids (isopimaric, dehydroabietic, and abietic acids) in a continuous-flow freshwater system. The total nominal concentrations of resin acids in the exposure tanks were 10, 50, and 100 {micro}g/L; the diesel WSF was generated in situ and provided a mean hydrocarbon concentration of 2.0 {+-} 0.1 mg/L (n = 12) during the 9-d exposure period. Exposure to the diesel WSF alone depressed liver bilirubin UDP-glucuronosyl transferase (UDPGT) activity and induced phenol UDPGT activity. Exposure to the diesel WSF in the absence or presence of resin acids induced liver cytochrome P4501A and increased the concentrations in the plasma of the enzymes lactate dehydrogenase, alkaline phosphatase, and glutamic oxaloacetic transaminase. The combined exposure to diesel WSF with either 50 or 100 {micro}g/L total resin acid caused significant elevations in the concentrations of bilirubin in the plasma and many of these fish had yellow pigmentation on the ventral surface and around the gill arches. The results demonstrate that exposure to combinations of two groups of contaminants can result in the manifestation of toxic effects not apparent from exposure to either of these chemicals in isolation.

  3. Oxidative degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) in subcritical and supercritical waters.

    Science.gov (United States)

    Hashimoto, M; Taniguchi, S; Takanami, R; Giri, R R; Ozaki, H

    2010-01-01

    Presence of chlorinated organic compounds in water bodies has become a concern among governments, health authorities and general public. Oxidation of organic compounds in water under high temperature and pressure is considered as a promising technique, but usefulness of the technique to mineralize 2,4-dichlorophenoxyacetic acid (2,4-D) is not well understood. This article aimed to elucidate degradation characteristics of 2,4-D in both subcritical and supercritical waters by laboratory batch experiments. 2,4-D degradation, total organic carbon (TOC) removal and dechlorination increased with increasing reaction time and temperature especially in subcritical waters, while dechlorination was a major step. 2,4-dichlorophenol (2,4-DCP) and acetic acid were the main degradation intermediates both in subcritical and supercritical waters. Though 2,4-D disappeared almost completely in subcritical waters near critical region ( approximately 99%), significant amounts of TOC and organic chlorine still remained as 2,4-DCP and acetic acid. But TOC removal and dechlorination were significantly enhanced ( approximately 95 and 91% respectively) in supercritical waters. Complete mineralization of 2,4-D in subcritical waters required a considerably longer reaction period, while the mineralization was almost complete within a short reaction period in supercritical waters. This is an important information of practical significance for oxidative degradation of chlorinated pesticides similar to 2,4-D.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-09-15

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

  5. Thermal rearrangement of novolak resins used in microlithography

    Science.gov (United States)

    Hardy, Ricky; Zampini, Anthony; Monaghan, Michael J.; O'Leary, Michael J.; Cardin, William J.; Eugster, Timothy J.

    1995-06-01

    Changes in phenolic-formaldehyde resin properties are described in terms of thermal exposure. At high temperature, resin molecular weight, dissolution properties and chemical composition change depending on the presence or absence of monomers. Without monomer in the resin melt at 220 degree(s)C, resin molecular weight increases with a corresponding decrease in dissolution rate. In the presence of monomer, molecular weight generally decreases. Dissolution rate may fluctuate depending on the monomer mixture. Three,five- Xylenol and 2,3,5-trimethylphenol co-monomers induced the most extreme changes in resin properties with thermal treatment. Resin degradation-recombination processes suggest a classical Friedel-Craft rearrangement mechanism.

  6. Plastic casting resin poisoning

    Science.gov (United States)

    Epoxy poisoning; Resin poisoning ... Epoxy and resin can be poisonous if they are swallowed or their fumes are breathed in. ... Plastic casting resins are found in various plastic casting resin products.

  7. Resistance to fracture of endodontically treated premolars restored with glass ionomer cement or acid etch composite resin: An in vitro study

    Directory of Open Access Journals (Sweden)

    B Ranga

    2010-01-01

    Full Text Available Aim: Due to the weakness of endodontically treated posterior teeth requires more strengthened restoration to withstand occlusal forces. The purpose of the present study was to determine and compare the resistance to fracture of endodontically treated maxillary 1 st premolars restored with different materials in mesio-occluso-distal (MOD cavity preparations. Materials and Methods: MOD cavity preparations in 80 endodontically treated maxillary 1 st premolars were restored using four different methods. Fiber rings were filled with stone plaster and the teeth were placed into the plaster up to the level of cemento-enamel junction. The teeth were grouped according to restorative method, mounted in an Instrom T.T. machine, and the buccal walls subjected to a slowly increasing compressive force until fracture occurred. Result: The force of fracture of the walls of each tooth was recorded and the results in the various groups compared. All teeth fractured in a similar manner irrespective of the restorative method used. Conclusion: The resistance to the fracture of the teeth was the same when they were stored with glass ionomer cement as a base over which composite resin was placed. When the entire cavities were filled with glass ionomer cement, the resistance to fracture of the teeth decreased significantly compared with the acid etch resin technique.

  8. Effect of a self-etching primer and phosphoric acid etching on the bond strength of 4-META/MMA-TBB resin to human enamel.

    Science.gov (United States)

    Nogawa, Hiroshi; Koizumi, Hiroyasu; Saiki, Osamu; Hiraba, Haruto; Nakamura, Mitsuo; Matsumura, Hideo

    2015-01-01

    The purpose of this study was to evaluate the shear bond strength and durability of 4-META/MMA-TBB resin to human enamel. A self-etching primer that contained 4-META (Teeth Primer, TP) and 35-45% or 60-65% concentrations of phosphoric acid (K-Etchant Gel, KE, and Super Bond C&B Red Activator, RA) were used as the surface treatment agents. A methyl methacrylate (MMA)-based self-polymerizing resin (Super-Bond C&B) was used as a luting agent. The shear bond strength was determined both pre and post thermocycling. The results were statistically analyzed with a non-parametric procedure. The post-thermocycling shear bond strength of the TP group was significantly higher than that of other groups, and that of the KE group was significantly higher compared with the RA group. These results demonstrated that 4-META was effective. Furthermore, when the degree of tooth demineralization was compared, surface treatment with less demineralization using TP was the most effective treatment.

  9. Leaf oil and resin acid components of lacebark pine, pinus bungeana zucc. Shiromatsu no ha no seiyu oyobi jushi san seibun

    Energy Technology Data Exchange (ETDEWEB)

    Ueda, Nasuo; Dewa, Naoyuki; Tsuneya, Tomoyuki (Tottori Univ., Tottori (Japan). Faculty of General Education); Kageyama, Mikiko; Nakajima, Akira; Yamamoto, Jiro; Nakajima, Ruka (Shiono Koryo Co. Ltd., Osaka (Japan))

    1989-11-30

    This study had the objective to search for the leafoil component of lacebark pine (Pinus bungeana Zucc), compare it with those of several other pines and Sciadopitys verillata Sieb, et Zucc whose fragrance comparatively resembles that of lacebark pine, and clarify the difference of fragrance. In addition, with regard to the resin acid component of resin, its comparison with those of red pine and black pine was made, and furthermore, in order to clarify the feature of the fragrance of lacebark pine, comparison by the enfleurage method was made with red pine, black pine and the above Sciadopitys. The leaf oils were extracted by steam distillation on the basis of making the extraction conditions such as the amount of samples, distillation time, and the amount of distillate, etc. as same as possible. As a result, with regard to the yield of the oil obtained by steam distillation, lacebark pine {prime} s was extremely big and almost twice more than those of black pine and red pine. Concerning the oil component, lacebark pine showed especially high contents of {alpha} -thujene, {alpha} -pinene and camphene and high contents of {beta} -caryophyllene and germacrene-D. Black pine had much of pinene and red pine had much of myrcene, etc. 21 refs., 2 figs., 4 tabs.

  10. Interactions of natural resins and pigments in works of art.

    Science.gov (United States)

    Poli, Tommaso; Piccirillo, Anna; Nervo, Marco; Chiantore, Oscar

    2017-10-01

    The degradation process involving the formation of metal soaps in drying oils is a well-known problem due to cations from pigments reacting with free fatty acids from the oil. The aggregation of these carboxylates in semi-crystalline structures can lead to eruptions through the paint layers and 'blooming' on the surface. In this work, the metal soaps formation in presence of natural resins has been assessed and studied by means of Fourier transform infrared spectroscopy with experiments concerning the ageing of drying oil and different natural resins (shellac, dammar and colophony) in the presence of common historic pigments (smalt, ochre, umber, azurite, lead white, zinc white and titanium white). Mixtures of resins and pigments have been exposed to photo-ageing in solar box up to 1000h, thermal ageing at 50°C up to 1100h and 6month of room conditions exposure as reference. The decrease in the intensity of the carbonyl band in the spectra, as well as the contemporary increase of the metal carboxylates (in the range from 1500 to 1650cm -1 ) absorption bands, were used as the main indicators of metal soap formation. It has been observed that some pigments, particularly zinc white and smalt, present a 'catalytic' effect favouring the simultaneous formation of associated oxalates. The formation of oxalates and different degradation products from natural resins in the presence of pigments is particularly important, as it deeply affects the removability of varnishes and, more generally, the cleaning processes. Moreover, it permanently modifies the interface between painting and varnish layers as well as the aesthetic aspects of the painted surfaces. The influence of natural resins reactivity with pigments and their role in the oxalate formation is an issue still unexplored. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Resin composites

    DEFF Research Database (Denmark)

    Benetti, Ana Raquel; Peutzfeldt, Anne; Lussi, Adrian

    2014-01-01

    OBJECTIVE: To investigate how the modulus of elasticity of resin composites influences marginal quality in restorations submitted to thermocyclic and mechanical loading. METHODS: Charisma, Filtek Supreme XTE and Grandio were selected as they were found to possess different moduli of elasticity...... of resin composite (p=0.81) on the quality of dentine margins was observed, before or after loading. Deterioration of all margins was evident after loading (p....008). CONCLUSIONS: The resin composite with the highest modulus of elasticity resulted in the highest number of gap-free enamel margins but with an increased incidence of paramarginal enamel fractures. CLINICAL SIGNIFICANCE: The results from this study suggest that the marginal quality of restorations can...

  12. Synthesis and curing of alkyd enamels based on ricinoleic acid

    Directory of Open Access Journals (Sweden)

    Jovičić Mirjana C.

    2010-01-01

    Full Text Available A combination of an alkyd resin with a melamine-formaldehyde resin gives a cured enamel film with the flexibility of the alkyd constituent and the high chemical resistance and hardness of the melamine resin at the same time. The melamine resin is a minor constituent and plays the role of a crosslinking agent. In this paper, alkyd resins of high hydroxyl numbers based on trimethylolpropane, ricinoleic acid and phthalic anhydride were synthesized. Two alkyds having 30 and 40 wt% of ricinoleic acid were formulated by calculation on alkyd constant. Alkyds were characterized by FTIR and by the determination of acid and hydroxyl numbers. Then synthesized alkyds were made into baking enamels by mixing with melamine-formaldehyde resins (weight ratio of 70:30 based on dried mass. Two types of commercial melamine resins were used: threeisobutoxymethyl melamine-formaldehyde resin (TIMMF and hexamethoxymethyl melamine resin (HMMMF. Prepared alkyd/melamine resin mixtures were cured in a differential scanning calorimeter (DSC under non-isothermal mode. Apparent degree of curing as a function of temperature was calculated from the curing enthalpies. Kinetic parameters of curing were calculated using Freeman-Carroll method. TIMMF resin is more reactive with synthesized alkyds than HMMMF resin what was expected. Alkyd resin with 30 wt% of ricinoleic acid is slightly more reactive than alkyd with 40 wt% of ricinoleic acid, probably because it has the high contents of free hydroxyl and acid groups. The gel content, Tg, thermal stability, hardness, elasticity and impact resistance of coated films cured at 150°C for 60 min were measured. Cured films show good thermal stability since the onset of films thermal degradation determined by thermogravimetric analysis (TGA is observed at the temperatures from 281 to 329°C. Films based on alkyd 30 are more thermal stable than those from alkyd 40, with the same melamine resin. The type of alkyd resin has no significant

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

    Directory of Open Access Journals (Sweden)

    Gabriel C Baltazar

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

  14. Variability and determinants of wood dust and resin acid exposure during wood pellet production: measurement strategies and bias in assessing exposure-response relationships.

    Science.gov (United States)

    Hagström, Katja; Lundholm, Cecilia; Eriksson, Kare; Liljelind, Ingrid

    2008-11-01

    Production of wood pellets is a relatively new and expanding industry in which the exposure profiles differ from those in other wood-processing industries like carpentries and sawmills where there are lower levels of wood dust. Sixty-eight personal exposure measurements of wood dust (inhalable and total dust) and resin acids were collected for 44 participants at four production plants located in Sweden. Results were used to estimate within- and between-worker variability and to identify uniformly exposed groups and determinants of exposure. In addition, overexposure, whether the risk of the long-term mean exposure of a randomly selected worker exceeding the occupational exposure limit is acceptably low, was calculated as well as the underestimation of the exposure-response relationship (attenuation). Greater variability in exposure between work shifts than between workers was observed with the within-worker variation accounting for 57-99% of the total variance in the individual-based model. Several uniformly exposed groups were detected but were mostly associated with a between-worker variation of zero which is an underestimation of the between-worker variation but an indication of uniformly exposed groups. Cleaning was identified as a work task that increases exposure slightly; so reducing workers' exposure during this operation is advisable. The levels of wood dust were high and were found to pose unacceptable risks of overexposure at all plants for inhalable dust and at three out of four plants for total dust. These findings show that exposure to dust needs to be reduced in this industry. For resin acids, the exposure was classed as acceptable at all plants. According to an individual-based model constructed from the data, the level of attenuation was high, and thus there would be substantial bias in derived dose-response relationships.

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

    Directory of Open Access Journals (Sweden)

    Ghabbour, N.

    2011-03-01

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

    Un total de 177 cepas de bacterias ácido lácticas (LAB fueron aisladas en las primeras etapas de la fermentación de aceitunas verdes marroquíes Picholine, incluyendo Lactobacillus plantarum (44.63%, Lactobacillus pentosus (25.99%, Lactobacillus brevis (9.61% y Pediococcus pentosaceus (19.77%. Todos los aislados fueron evaluados mediante su tolerancia a extractos de hojas de olivo y oleuropeína. La mayoría de los aislados (85,3% degradaron oleuropeína, cuando fueron evaluados usando oleuropeína o 5-Bromo-4-cloro- 3-indolil β-D-glucuronido (X-Gluc como sustrato. La capacidad de biodegradación de las cepas seleccionadas para cada especie fue confirmada mediante análisis por HPLC.

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

    Science.gov (United States)

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

    2012-08-01

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

  17. Amycolatopsis oliviviridis sp. nov., a novel polylactic acid-bioplastic-degrading actinomycete isolated from paddy soil.

    Science.gov (United States)

    Penkhrue, Watsana; Sujarit, Kanaporn; Kudo, Takuji; Ohkuma, Moriya; Masaki, Kazuo; Aizawa, Tomoyasu; Pathom-Aree, Wasu; Khanongnuch, Chartchai; Lumyong, Saisamorn

    2018-03-08

    A novel bioplastic-degrading actinomycete, strain SCM_MK2-4 T , was isolated from paddy soil in Thailand. The 16S rRNA gene sequence showed that strain SCM_MK2-4 T belonged to the genus Amycolatopsis, with the highest sequence similarity to Amycolatopsisazurea JCM 3275 T (99.4 %), and was phylogenetically clustered with this strain along with Amycolatopsislurida JCM 3141 T (99.3 %), A. japonica DSM 44213 T (99.2 %), A. decaplanina DSM 44594 T (99.0 %), A. roodepoortensis M29 T (98.9 %), A. keratiniphilasubsp. nogabecina DSM 44586 T (98.8 %), A. keratiniphilasubsp. keratiniphila DSM 44409 T (98.5 %), A. orientalis DSM 40040 T (98.4 %) and A. regifaucium GY080 T (98.3 %). A combination of DNA-DNA hybridization results ranging from 42.8±3.2 to 66.2±1.4 % with the type strains of A. azurea and A. lurida and some different phenotypic characteristics indicated that the strain could be distinguished from its closest phylogenetic neighbours. Whole-cell hydrolysates of the strain were shown to contain meso-diaminopimelic acid, arabinose, galactose, glucose, ribose, mannose, rhamnose and xylose. The predominant menaquinone was MK-9(H4). The major cellular fatty acid profile consisted of iso-C15 : 0, iso-C16 : 0, summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2OH) and C16 : 0. The polar lipid composition of the strain consisted of phosphatidyl-N-methylethylethanolamine, phosphatidylethanolamine, hydroxyphosphatidylethanolamine, phosphatidylglycerol, aminophospholipids, an unidentified phospholipid and two unidentified glycolipids. The G+C content of the genomic DNA was 68.2 mol%. On the basis of phylogenetic analyses, DNA-DNA hybridization experimentation and the phenotypic characteristics, it was concluded that strain SCM_MK2-4 T represents a novel species of the genus Amycolatopsis, for which the name Amycolatopsisoliviviridis sp. nov. is proposed. The type strain is SCM_MK2-4 T (=TBRC 7186 T =JCM 32134 T ).

  18. Screening of indigenous oxalate degrading lactic acid bacteria from human faeces and South Indian fermented foods: assessment of probiotic potential.

    Science.gov (United States)

    Gomathi, Sivasamy; Sasikumar, Ponnusamy; Anbazhagan, Kolandaswamy; Sasikumar, Sundaresan; Kavitha, Murugan; Selvi, M S; Selvam, Govindan Sadasivam

    2014-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Sivasamy Gomathi

    2014-01-01

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

  20. Inoculation of Pichia kudriavzevii RB1 degrades the organic acids present in raw compost material and accelerates composting.

    Science.gov (United States)

    Nakasaki, Kiyohiko; Araya, Shogo; Mimoto, Hiroshi

    2013-09-01

    In this study, the yeast strain Pichia kudriavzevii RB1 was used as an inoculum to accelerate organic matter degradation of rabbit food with added organic acids, which was used as a model food waste for composting. The RB1 strain rapidly degraded the organic acids present in the raw compost material, leading to an increase in pH beyond the neutral level, within 2 days. Both mesophilic and thermophilic bacteria proliferated faster in the compost with RB1 inoculation than in that without inoculation. Although the yeast died with the increase in compost temperature, it affected the early stages of composting prior to the thermophilic stage and accelerated the composting process by 2 days by eliminating the initial lag phase seen in the growth of other microorganisms. Moreover, populations of Bacillus thermoamylovorans, Bacillus foraminis, and Bacillus coagulans became dominant during the thermophilic stages of both composting with and without RB1 inoculation. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Degradation of acidic Orange G dye using UV-H2O2 in batch ...

    African Journals Online (AJOL)

    Degradation of Orange G dye has been investigated using UV irradiation with hydrogen peroxide (H2O2) in a batch photoreactor. UV irradiation and H2O2 resulted in significant photodegradation of the dye although the effect individual reaction was very little. The degradation was studied to elucidate the effect of various ...

  2. Molecular distributions of dicarboxylic acids, ketocarboxylic acids and α-dicarbonyls in biomass burning aerosols: implications for photochemical production and degradation in smoke layers

    Directory of Open Access Journals (Sweden)

    A. Hoffer

    2010-03-01

    Full Text Available Aerosols in the size class <2.5 μm (6 daytime and 9 nighttime samples were collected at a pasture site in Rondônia, Brazil, during the intensive biomass burning period of 16–26 September 2002 as part of the Large-Scale Biosphere-Atmosphere Experiment in Amazonia – Smoke, Aerosols, Clouds, Rainfall and Climate (LBA-SMOCC. Homologous series of dicarboxylic acids (C2–C11 and related compounds (ketocarboxylic acids and α-dicarbonyls were identified using gas chromatography (GC and GC/mass spectrometry (GC/MS. Among the species detected, oxalic acid was found to be the most abundant, followed by succinic, malonic and glyoxylic acids. Average concentrations of total dicarboxylic acids, ketocarboxylic acids and α-dicarbonyls in the aerosol samples were 2180, 167 and 56 ng m−3, respectively. These are 2–8, 3–11 and 2–16 times higher, respectively, than those reported in urban aerosols, such as in 14 Chinese megacities. Higher ratios of dicarboxylic acids and related compounds to biomass burning tracers (levoglucosan and K+ were found in the daytime than in the nighttime, suggesting the importance of photochemical production. On the other hand, higher ratios of oxalic acid to other dicarboxylic acids and related compounds normalized to biomass burning tracers (levoglucosan and K+ in the daytime provide evidence for the possible degradation of dicarboxylic acids (≥C3 in this smoke-polluted environment. Assuming that these and related compounds are photo-chemically oxidized to oxalic acid in the daytime, and given their linear relationship, they could account for, on average, 77% of the formation of oxalic acid. The remaining portion of oxalic acid may have been directly emitted from biomass burning as suggested by a good correlation with the biomass burning tracers (K+, CO and ECa and organic carbon (OC. However, photochemical production from other precursors could not be excluded.

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

    Science.gov (United States)

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

    2014-12-01

    Skimmed milk spiked with five organophosphorus pesticides (OPPs), chlorpyrifos, diazinon, fenitrothion, malathion and methyl parathion, was fermented by ten lactic acid bacteria (LAB) and four strain combinations at 42°C for 24h. OPPs left in the samples at different times were extracted, purified, detected by gas chromatography and calculated for degradation rate constants, based on a first-order reaction model. OPPs degradation was enhanced by the inoculated LAB, resulting in 0.8-225.4% increase in the rate constants. Diazinon and methyl parathion were more stable whereas chlorpyrifos, fenitrothion and malathion were more labile. Lactobacillus brevis 1.0209 showed the strongest acceleration on OPPs degradation while strain combination could bring about a synergy between the strains of lower ability. Phosphatase production of the strains might be one of the key factors responsible for the enhanced OPPs degradation, as the detected phosphatase activities were positively correlated to the measured degradation rate constants of OPPs (r=0.636-0.970, P<0.05). Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Isolation and characterization of a novel 2-methyl-4-chlorophenoxyacetic acid-degrading Enterobacter sp. strain SE08.

    Science.gov (United States)

    Tan, Lin; Hu, Qiulong; Xiong, Xingyao; Su, Xiaojun; Huang, Yanning; Jiang, Ziwei; Zhou, Qingming; Zhao, Songyi; Zeng, Wei-ai

    2013-10-01

    A bacterial strain (SE08) capable of utilizing 2-methyl-4-chlorophenoxy acetic acid (MCPA) as the sole carbon and energy source for growth was isolated by continuous enrichment culturing in minimal salt medium (MSM) from a long term MCPA exposed soil. This bacterial strain was identified as Enterobacter sp. based on morphological, physiological and biochemical tests, as well as 16S rRNA sequence analysis. Its ability to degrade MCPA was determined using high performance liquid chromatography. The strain SE08 can tolerate unusually high MCPA concentrations (125-2000mg/L). The influences of culturing factors (initial concentration, pH, and temperature) on the bacterial growth and substrate degradation were studied. The results showed that the optimal MCPA degradation occurred at an MCPA concentration of 500mg/L, 30°C and pH 6.0. Under these conditions, 68.5 percent of MCPA in MSM was degraded by SE08, and the OD600nm reached 0.64 after culturing for 72h. The degradation of MCPA could be enhanced by addition of both carbon and nitrogen sources. At an initial MCPA concentration of 500mg/L, when 5g/L glucose and 2.5g/L yeast extract were added into the MSM media, the MCPA degradation was significantly increased to 83.8 percent, and OD600nm was increased to 1.09 after incubation at 30°C and pH 6.0 for 72h. This is the first study showing that an Enterobacter sp. strain is capable of degrading MCPA, which might provide a new approach for the remediation of MCPA contaminated soil and contribute to the limited knowledge about the function of Enterobacter species. Crown Copyright © 2013. Published by Elsevier Inc. All rights reserved.

  5. Synthesis, Chacterization, and Thermal Study of Terpolymeric Resin Derived from m-cresol, Hexamine and Formaldehyde

    Directory of Open Access Journals (Sweden)

    K. M. Khedkar

    2012-01-01

    Full Text Available Terpolymeric resin was prepared from m-cresol (0.1M, hexamine (0.05M and formaldehyde (0.2M by acid catalyzed polycondensation method using 1M HCl in temperature range of 122-130°C.The resin was abbreviated as m-CHF-I. The molecular weight of terpolymer was determined by non-aqueous conductometric titration technique. The structure of resin was determined by its elemental analysis, UV-VIS, IR, and NMR data. The thermokinetic parameters were determined using Freeman-Carroll (FC and Sharp Wentworth (SW method in temperature range (410-485°C.The values of activation energies (Ea, entropy (∆S, and free energies (∆G were in good agreement . The order of degradation reaction determined by FC method was confirmed by SW method.

  6. Flame Retardance and Physical Properties of Novel Cured Blends of Unsaturated Polyester and Furan Resins

    Directory of Open Access Journals (Sweden)

    Baljinder Kaur Kandola

    2015-02-01

    Full Text Available Novel blends of two furan resins with an unsaturated polyester have been prepared and cured by parallel free radical (for the unsaturated polyester and acid-catalysed crosslinking (for the furan resin to give co-cured composite materials. Although these materials have inferior physical properties, such as low Tg and low storage modulus compared with those of unsaturated polyester and furan resins alone, they show markedly improved flame retardance compared with that of the normally highly flammable unsaturated polyester. This increased flame retardance arises from a condensed phase mechanism in which the furanic component forms a semi-protective char, reducing rates of thermal degradation and total heat release and heat of combustion. The blends also burn with reduced smoke output compared with that from unsaturated polyester alone.

  7. Synthesis of novel chitosan resin derivatized with serine diacetic acid moiety and its application to on-line collection/concentration of trace elements and their determination using inductively coupled plasma-atomic emission spectrometry.

    Science.gov (United States)

    Hakim, Lukman; Sabarudin, Akhmad; Oshima, Mitsuko; Motomizu, Shoji

    2007-04-04

    A novel chelating resin functionalized with serine diacetic acid moiety was synthesized by using chitosan as base material, and applied to the collection/concentration of trace elements in environmental water samples, followed by the determination using inductively coupled plasma-atomic emission spectrometer (ICP-AES). The synthesized resin, crosslinked chitosan serine diacetic acid (CCTS-SDA), showed good adsorption behavior toward trace amounts of Cd, Pb, Cu, Ni, V, Ga, Sc, In, and Th in a wide pH range. Additionally, rare earth elements also can be retained on the resin at neutral pH region. The adsorbed elements can be easily eluted with 1 mol L(-1) of nitric acid, and their recoveries were found to be 90-100%. The CCTS-SDA was packed in a mini-column, which was then installed in a computer-controlled auto-pretreatment system (Auto-Pret System) for on-line trace elements collection and determination with ICP-AES. Experimental parameters which related to the improvement of sensitivity and reproducibility were optimized. The limits of detection (LOD) for 13 elements were found to be in sub-ppb level. The proposed method with CCTS-SDA resin was successfully applied to the determination of trace elements in river water samples. The method was validated by determining a certified reference material of river water, SLRS-4.

  8. Mechanism of Acetyl Salicylic Acid (Aspirin Degradation under Solar Light in Presence of a TiO2-Polymeric Film Photocatalyst

    Directory of Open Access Journals (Sweden)

    Debjani Mukherjee

    2016-04-01

    Full Text Available Application of titanium dioxide (TiO2 as a photocatalyst has presented a promising avenue for the safe photocatalytic degradation of pollutants. Increasing levels of the release of pharmaceuticals in the environment and formation of the intermediates during their degradation may impose health and environmental risks and therefore require more attention. Photocatalytic degradation of acetylsalicylic acid (aspirin was carried out in the presence of the TiO2-filled polymeric film as a photocatalyst under solar light irradiation. The polymeric film incorporates TiO2 in the matrix, which acts as a photocatalyst under solar illumination and degrades the acetyl salicylic acid (ASA into a range of organic compounds before complete demineralization (formation of carbon dioxide and water as final products. Among the intermediates, acetic acid was found to be present in a larger amount compared to other organic acids. The qualitative/quantitative analyses of the intermediates resulted in the determination of the most probable reaction’s mechanism in the degradation process. The mechanism of degradation of acetylsalicylic acid and its reaction pathway were developed from liquid chromatography/mass spectroscopy (LC/MS, Fourier Transform Infra Red (FTIR and UV spectrophotometric analysis. It was found that hydroxyl groups were dominant in the degradation process compared to electrons and holes generated by TiO2. The total organic carbon (TOC analysis was also carried out to analyze the organic carbon content of the intermediates formed during the course of degradation.

  9. Concentrating cesium-137 from seawater using resorcinol-formaldehyde resin for radioecological monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Egorin, Andrei; Tokar, Eduard; Tutov, Mikhail; Avramenko, Valentin [Institute of Chemistry FEBRAS, Vladivostok (Russian Federation); Far Eastern Federal Univ., Vladivostok (Russian Federation); Palamarchuk, Marina; Marinin, Dmitry [Institute of Chemistry FEBRAS, Vladivostok (Russian Federation)

    2017-04-01

    A method of preconcentrating cesium-137 from seawater using a resorcinol-formaldehyde resin, which enables one to optimize the ecological monitoring procedure, has been suggested. Studies of sorption of cesium-137 from seawater by resorcinol-formaldehyde resin have been performed, and it has been demonstrated that the cation exchanger is characterized by high selectivity with respect to cesium-137. It was found that the selectivity depended on the temperature of resin solidification and the seawater pH value. The maximal value of the cesium-137 distribution coefficient is equal to 4.1-4.5 x 10{sup 3} cm{sup 3} g{sup -1}. Under dynamic conditions, the ion-exchange resin capacity is 310-910 bed volumes depending on the seawater pH, whereas the efficiency of cesium removal exceeds 95%. The removal of more than 95% of cesium-137 has been attained using 1-3 M solutions of nitric acid: here, the eluate volume was 8-8.4 bed volumes. Application of 3 M solution of nitric acid results in resin degradation with the release of gaseous products.

  10. 2,4-Dichlorophenoxyacetic acid (2,4-D)- and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T)-degrading gene cluster in the soybean root-nodulating bacterium Bradyrhizobium elkanii USDA94.

    Science.gov (United States)

    Hayashi, Shohei; Sano, Tomoki; Suyama, Kousuke; Itoh, Kazuhito

    2016-01-01

    Herbicides 2,4-dichlorophenoxyacetic acid (2,4-D)- and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T)-degrading Bradyrhizobium strains possess tfdAα and/or cadABC as degrading genes. It has been reported that root-nodulating bacteria belonging to Bradyrhizobium elkanii also have tfdAα and cadA like genes but lack the ability to degrade these herbicides and that the cadA genes in 2,4-D-degrading and non-degrading Bradyrhizobium are phylogenetically different. In this study, we identified cadRABCK in the genome of a type strain of soybean root-nodulating B. elkanii USDA94 and demonstrated that the strain could degrade the herbicides when cadABCK was forcibly expressed. cadABCK-cloned Escherichia coli also showed the degrading ability. Because co-spiked phenoxyacetic acid (PAA) could induce the degradation of 2,4-D in B. elkanii USDA94, the lack of degrading ability in this strain was supposed to be due to the low inducing potential of the herbicides for the degrading gene cluster. On the other hand, tfdAα from B. elkanii USDA94 showed little potential to degrade the herbicides, but it did for 4-chlorophenoxyacetic acid and PAA. The 2,4-D-degrading ability of the cad cluster and the inducing ability of PAA were confirmed by preparing cadA deletion mutant. This is the first study to demonstrate that the cad cluster in the typical root-nodulating bacterium indeed have the potential to degrade the herbicides, suggesting that degrading genes for anthropogenic compounds could be found in ordinary non-degrading bacteria. Copyright © 2016 Elsevier GmbH. All rights reserved.

  11. A kinetic study on the decomposition of 5-hydroxymethylfurfural into levulinic acid

    NARCIS (Netherlands)

    Girisuta, B.; Janssen, L. P. B. M.; Heeres, H. J.

    2006-01-01

    Levulinic acid (LA), accessible by the acid catalyzed degradation of biomass, is potentially a very versatile green intermediate chemical for the synthesis of various (bulk) chemicals for applications like fuel additives, polymers, and resin precursors. We report here a kinetic study on one of the

  12. Wet degradation of keratin proteins : Linking amino acid, elemental and isotopic composition

    NARCIS (Netherlands)

    Von Holstein, I. C C; Penkman, Kirsty E H; Peacock, E.E.; Collins, M. J.

    2014-01-01

    Rationale Archaeological keratin samples are increasingly the subject of palaeodietary, provenancing and dating studies. Keratin samples from wet archaeological contexts are microbiologically and chemically degraded, causing differential diagenesis of protein structures in hair fibres. The effects

  13. Characterization and Computation of Yb/TiO₂ and Its Photocatalytic Degradation with Benzohydroxamic Acid.

    Science.gov (United States)

    Luo, Xianping; Zhu, Sipin; Wang, Junyu; Wang, Chunying; Wu, Min

    2017-11-28

    Yb-doped TiO₂ (Yb/TiO₂) compositions were synthesized by sol-gel method, and the prepared materials were characterized by X-ray Diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-visible diffuse-reflectance spectrum (UV-Vis DRS), transmission electron microscope (TEM) and high resolution transmission electron microscope (HRTEM), energy dispersive spectrometer (EDS), and N₂ adsorption. A beneficiation reagent of benzohydroxamic acid (BHA) was used to test the photocatalytic activity of Yb/TiO₂. The characterizations indicate that the doping of Yb could inhibit the crystal growth of TiO₂, enhance the specific surface area, increase the binding energy of Ti2p, and also slightly expand the adsorption ranges to visible light. Furthermore, the computation of band structure also indicates that Yb-doped TiO₂ could make the forbidden band narrower than pure anatase TiO₂, which presents a red shift in the absorption spectrum. As a result of the photodegradation experiment on BHA, Yb/TiO₂ (0.50% in mass) sintered at 450 °C displayed the highest catalytic activity for BHA when compared with pure TiO₂ or other doped Yb/TiO₂ compositions, and more than 89.2% of the total organic carbon was removed after 120 min. Almost all anions, including Cl - , HCO₃ - , NO₃ - , and SO₄ 2- , inhibited the degradation of BHA by Yb/TiO₂, and their inhibition effects followed the order of HCO₃ - > NO₃ - > SO₄ 2- > Cl - . Cations of Na⁺, K⁺, Ca 2+ , and Mg 2+ displayed a slight suppressing effect due to the impact of Cl - coexisting in the solution. In addition, Yb/TiO₂ maintained a high photocatalytic ability with respect to BHA after four runs. It is hypothesized that ·OH is one of the main species involved in the photodegradation of BHA, and the mutual transformation of Yb 3+ and Yb 2+ could promote the separation of electron-hole pairs.

  14. Characterization and Computation of Yb/TiO2 and Its Photocatalytic Degradation with Benzohydroxamic Acid

    Directory of Open Access Journals (Sweden)

    Xianping Luo

    2017-11-01

    Full Text Available Yb-doped TiO2 (Yb/TiO2 compositions were synthesized by sol-gel method, and the prepared materials were characterized by X-ray Diffraction (XRD, X-ray photoelectron spectroscopy (XPS, UV-visible diffuse-reflectance spectrum (UV-Vis DRS, transmission electron microscope (TEM and high resolution transmission electron microscope (HRTEM, energy dispersive spectrometer (EDS, and N2 adsorption. A beneficiation reagent of benzohydroxamic acid (BHA was used to test the photocatalytic activity of Yb/TiO2. The characterizations indicate that the doping of Yb could inhibit the crystal growth of TiO2, enhance the specific surface area, increase the binding energy of Ti2p, and also slightly expand the adsorption ranges to visible light. Furthermore, the computation of band structure also indicates that Yb-doped TiO2 could make the forbidden band narrower than pure anatase TiO2, which presents a red shift in the absorption spectrum. As a result of the photodegradation experiment on BHA, Yb/TiO2 (0.50% in mass sintered at 450 °C displayed the highest catalytic activity for BHA when compared with pure TiO2 or other doped Yb/TiO2 compositions, and more than 89.2% of the total organic carbon was removed after 120 min. Almost all anions, including Cl−, HCO3−, NO3−, and SO42−, inhibited the degradation of BHA by Yb/TiO2, and their inhibition effects followed the order of HCO3− > NO3− > SO42− > Cl−. Cations of Na+, K+, Ca2+, and Mg2+ displayed a slight suppressing effect due to the impact of Cl− coexisting in the solution. In addition, Yb/TiO2 maintained a high photocatalytic ability with respect to BHA after four runs. It is hypothesized that ·OH is one of the main species involved in the photodegradation of BHA, and the mutual transformation of Yb3+ and Yb2+ could promote the separation of electron-hole pairs.

  15. Effect of a low-viscosity adhesive resin on the adhesion of metal brackets to enamel etched with hydrochloric or phosphoric acid combined with conventional adhesives.

    Science.gov (United States)

    Yetkiner, Enver; Ozcan, Mutlu; Wegehaupt, Florian Just; Wiegand, Annette; Eden, Ece; Attin, Thomas

    2013-12-01

    This study investigated the effect of a low-viscosity adhesive resin (Icon) applied after either hydrochloric (HCl) or phosphoric acid (H3PO4) on the adhesion of metal brackets to enamel. Failure types were analyzed. The crowns of bovine incisors (N = 20) were sectioned mesio-distally and inciso-gingivally, then randomly assigned to 4 groups according to the following protocols to receive mandibular incisor brackets: 1) H3PO4 (37%)+TransbondXT (3M UNITEK); 2) H3PO4 (37%)+Icon+TransbondXT; 3) HCl (15%)+Icon (DMG)+TransbondXT 4) HCl (15%)+Icon+Heliobond (Ivoclar Vivadent)+TransbondXT. Specimens were stored in distilled water at 37°C for 24 h and thermocycled (5000x, 5°C to 55°C). The shear bond strength (SBS) test was performed using a universal testing machine (1 mm/min). Failure types were classified according to the Adhesive Remnant Index (ARI). Contact angles of adhesive resins were measured (n = 5 per adhesive) on ceramic surfaces. No significant difference in SBS was observed, implying no difference between combinations of adhesive resins and etching agents (p = 0.712; ANOVA). The Weibull distribution presented significantly lower Weibull modulus (m) of group 3 (m = 2.97) compared to other groups (m = 5.2 to 6.6) (p group 1 (45.4 ± 7.9) > group 2 (44.2 ± 10.6) > group 3 (42.6 ± 15.5). While in groups 1, 3, and 4 exclusively an ARI score of 0 (no adhesive left on tooth) was observed, in group 2, only one specimen demonstrated score 1 (less than half of adhesive left on tooth). Contact angle measurements were as follows: Icon (25.86 ± 3.81 degrees), Heliobond (31.98 ± 3.17 degrees), TransbondXT (35 ± 2.21 degrees). Icon can be safely used with the conventional adhesives tested on surfaces etched with either HCl or H3PO4.

  16. Aging in CTBN modified epoxy resin stocks

    International Nuclear Information System (INIS)

    Creed, K.E. Jr.

    1979-01-01

    The cause of degradation in the glass transition temperature (T/sub G/) of a partially crystallized polymer was investigated. Sample epoxy resin filled capacitors were cured at 90 0 C for 24 hours, then stored at room atmospheric conditions. These showed typical degradation in T/sub G/ after storage for one month. One set of epoxy resin castings was stored at room atmosphere and another set was stored in a dry box at 0% relative humidity and 27 0 C. The samples at room atmospheric conditions showed typical degradation in T/sub G/, while the T/sub G/ for those stored in the dry box increased. Further tests were then made on epoxy resin castings at various curing temperatures and times at both room atmosphere and 0% humidity. Resulting data indicated that absorption of moisture during storage was the predominant cause of T/sub G/ degradation, with stress relaxation another, though smaller, contributing factor

  17. Kinetic, equilibrium and thermodynamic studies on sorption of uranium and thorium from aqueous solutions by a selective impregnated resin containing carminic acid

    Energy Technology Data Exchange (ETDEWEB)

    Rahmani-Sani, Abolfazl [Wastewater Division, Faculty of Health, Sabzevar University of Medical Sciences, PO Box 319, Sabzevar (Iran, Islamic Republic of); Hosseini-Bandegharaei, Ahmad, E-mail: ahoseinib@yahoo.com [Wastewater Division, Faculty of Health, Sabzevar University of Medical Sciences, PO Box 319, Sabzevar (Iran, Islamic Republic of); Department of Engineering, Kashmar Branch, Islamic Azad University, PO Box 161, Kashmar (Iran, Islamic Republic of); Hosseini, Seyyed-Hossein [Department of Engineering, Kashmar Branch, Islamic Azad University, PO Box 161, Kashmar (Iran, Islamic Republic of); Kharghani, Keivan [Water Division, Department of Engineering, Torbat-e-Hydarieh Branch, Islamic Azad University, PO Box 121, Torbat-e-Hydarieh (Iran, Islamic Republic of); Zarei, Hossein [Department of Engineering, Kashmar Branch, Islamic Azad University, PO Box 161, Kashmar (Iran, Islamic Republic of); Rastegar, Ayoob [Wastewater Division, Faculty of Health, Sabzevar University of Medical Sciences, PO Box 319, Sabzevar (Iran, Islamic Republic of); Department of Engineering, Kashmar Branch, Islamic Azad University, PO Box 161, Kashmar (Iran, Islamic Republic of)

    2015-04-09

    Highlights: • The objective of the study is to investigate the potential application of a selective EIR for sorption of U(VI) and Th(IV) ions. • The effects of several physiochemical parameters were investigated. • The sorption kinetics and sorption isotherms were used to explain the sorption mechanism. • The thermodynamic studies showed the feasibility of sorption process. • The EIR beads showed a great potential for effective removal of U(VI) and Th(IV) ions. - Abstract: In this work, the removal of uranium and thorium ions from aqueous solutions was studied by solid–liquid extraction using an advantageous extractant-impregnated resin (EIR) prepared by loading carminic acid (CA) onto Amberlite XAD-16 resin beads. Batch sorption experiments using CA/XAD-16 beads for the removal of U(VI) and Th(IV) ions were carried out as a function of several parameters, like equilibration time, metal ion concentration, etc. The equilibrium data obtained from the sorption experiments were adjusted to the Langmuir isotherm model and the calculated maximum sorption capacities in terms of monolayer sorption were in agreement with those obtained from the experiments. The experimental data on the sorption behavior of both metal ions onto the EIR beads fitted well in both Bangham and intra-particle diffusion kinetic models, indicating that the intra-particle diffusion is the rate-controlling step. The thermodynamic studies at different temperatures revealed the feasibility and the spontaneous nature of the sorption process for both uranium and thorium ions.

  18. Determination of isotopic composition of dissolved copper in seawater by multi-collector inductively coupled plasma mass spectrometry after pre-concentration using an ethylenediaminetriacetic acid chelating resin

    International Nuclear Information System (INIS)

    Takano, Shotaro; Tanimizu, Masaharu; Hirata, Takafumi; Sohrin, Yoshiki

    2013-01-01

    Graphical abstract: -- Highlights: •A simple analytical method for determining the Cu isotopic composition in seawater using an ethylenediaminetriacetic acid chelating resin was developed. •The accuracy was evaluated via addition of NIST SRM976 or 65 Cu-enriched standard to seawater. •δ 65 Cu of seawater reference materials (i.e., CASS-5 and NASS-6) and seawater samples from the northwestern Pacific Ocean were firstly determined. -- Abstract: Copper is an essential trace metal that shows a vertical recycled-scavenged profile in the ocean. To help elucidate the biogeochemical cycling of Cu in the present and past oceans, it is important to determine the distribution of Cu isotopes in seawater. However, precise isotopic analysis of Cu has been impaired by the low concentrations of Cu as well as co-existing elements that interfere with mea