WorldWideScience

Sample records for chemical degradation

  1. Photo, thermal and chemical degradation of riboflavin

    Directory of Open Access Journals (Sweden)

    Muhammad Ali Sheraz

    2014-08-01

    Full Text Available Riboflavin (RF, also known as vitamin B2, belongs to the class of water-soluble vitamins and is widely present in a variety of food products. It is sensitive to light and high temperature, and therefore, needs a consideration of these factors for its stability in food products and pharmaceutical preparations. A number of other factors have also been identified that affect the stability of RF. These factors include radiation source, its intensity and wavelength, pH, presence of oxygen, buffer concentration and ionic strength, solvent polarity and viscosity, and use of stabilizers and complexing agents. A detailed review of the literature in this field has been made and all those factors that affect the photo, thermal and chemical degradation of RF have been discussed. RF undergoes degradation through several mechanisms and an understanding of the mode of photo- and thermal degradation of RF may help in the stabilization of the vitamin. A general scheme for the photodegradation of RF is presented.

  2. Chemical degradation of fluoroelastomer in an alkaline environment

    DEFF Research Database (Denmark)

    Mitra, S.; Ghanbari-Siahkali, A.; Kingshott, P.;

    2004-01-01

    bond formation on the rubber backbone which accelerates the degradation even further with longer exposure. Furthermore, the cross-link sites of the exposed rubber samples are also found to be vulnerable to hydrolytic attack under the studied chemical environment as evidenced by the decrease in cross......We have investigated the time-dependent chemical degradation of a fluoroelastomer, FKM (Viton((R)) A), in an alkaline environment (10% NaOH, 80 degreesC). Optical microscopy and SEM analysis reveal that degradation starts with surface roughness right from the earliest stage of exposure (e.g., 1...... of this surface degradation is found to be strong enough to affect the bulk mechanical properties. The molecular mechanisms of the surface chemical degradation were determined using surface analysis (XPS and ATR-FTIR) where the initial degradation was found to proceed via dehydrofluorination. This leads to double...

  3. Investigations on the Chemical Degradation of Silver Gelatine Prints

    OpenAIRE

    Maha Ahmed ALI; Mona Fouad ALI; Mohammed Osama SAKER; Abdel Azez El Bayoumi ABDEL ALEEM; Khaled Ibrahim EL NAGAR

    2012-01-01

    Photographs are considered composite objects with complex chemical and physical structures. Therefore they are more prone to damage as compared to other objects. Chemical degradation is by far the most common decay form found among photographic collections. This study investigates the chemical degradation of silver gelatin prints (DOP) and the reaction of the image, silver, gelatin, and paper to accelerated aging, to the action of light, and oxidizing gases, in terms of their physical and che...

  4. Polymer scaffold degradation control via chemical control

    Science.gov (United States)

    Hedberg-Dirk, Elizabeth L.; Dirk, Shawn; Cicotte, Kirsten

    2016-01-05

    A variety of polymers and copolymers suitable for use as biologically compatible constructs and, as a non-limiting specific example, in the formation of degradable tissue scaffolds as well methods for synthesizing these polymers and copolymers are described. The polymers and copolymers have degradation rates that are substantially faster than those of previously described polymers suitable for the same uses. Copolymers having a synthesis route which enables one to fine tune the degradation rate by selecting the specific stoichiometry of the monomers in the resulting copolymer are also described. The disclosure also provides a novel synthesis route for maleoyl chloride which yields monomers suitable for use in the copolymer synthesis methods described herein.

  5. Effect of chemical degradation on fluxes of reactive compounds

    Directory of Open Access Journals (Sweden)

    J. Rinne

    2011-12-01

    Full Text Available In the analyses of VOC fluxes measured above plant canopies, one usually assumes the flux above canopy to equal the emission at the surface. Thus one assumes the chemical degradation to be much slower than the turbulent transport. We used a stochastic Lagrangian transport model in which the chemical degradation was described as first order decay in order to study the effect of the chemical degradation on above canopy fluxes of chemically reactive species. With the model we explored the sensitivity of the ratio of the above canopy flux to the surface emission on several parameters such as chemical lifetime of the compound, friction velocity, stability, and canopy density. Our results show that friction velocity and chemical lifetime affected the loss during transport the most. The canopy density had a significant effect if the chemically reactive compound was emitted from the forest floor. We used the results of the simulations together with oxidant data measured during HUMPPA-COPEC-2010 campaign at a Scots pine site to estimate the effect of the chemistry on fluxes of three typical biogenic VOCs, isoprene, α-pinene, and β-caryophyllene. Of these, the chemical degradation had a~major effect on the fluxes of the most reactive species β-caryophyllene, while the fluxes of α-pinene were affected during nighttime. For these two compounds representing the mono- and sesquiterpenes groups, the effect of chemical degradation had also a significant diurnal cycle with the highest chemical loss at night. The different day and night time loss terms need to be accounted for, when measured fluxes of reactive compounds are used to reveal relations between primary emission and environmental parameters.

  6. Photochemical and microbial degradation technologies to remove toxic chemicals

    International Nuclear Information System (INIS)

    An effort was made to apply photochemical degradation technology on biodegradation processes to increase the bioremediation potential of microbial actions. For this purpose, we have chosen Phanerochaete chrysosporium, a wood decaying white-rot fungus and a variety of chlorinated pesticides and aromatics as study materials. By using UV-irradiation and benomyl (a commonly used fungicide) as selection methods, a strain of UV-resistant P. chrysosporium was developed. This strain was found to be capable of rapidly degrading these chlorinated chemicals when they were incubated in N-deficient medium which received 1 hr/day of UV-irradiation. UV-irradiation either at 300 or 254 nm showed the beneficial effect of speeding up the rate of degradation on most of test chemicals with the exception of toxaphene and HCH (hexachlorocyclohexane). By adding fresh glucose to the medium it was possible to maintain high degradation capacity for several weeks

  7. Radiation-chemical degradation of cellulose and other polysaccharides

    International Nuclear Information System (INIS)

    Results of studies on the radiation-chemical transformations of cellulose, its ethers, and some other polysaccharides (xylan, starch, dextran, chitin, chitosan, and heparin) are discussed. Ionising radiation causes the degradation of these compounds accompanied by decomposition of the pyranose ring and formation of compounds with carbonyl and carboxy groups, as well as formation of hydrogen, carbon dioxide, and carbon monoxide. The efficiency of degradation increases considerably with temperature and depends on the structure of the polysaccharide and the nature of its substituents. A mechanism of the radiation-chemical transformations of cellulose and other polysaccharides is suggested. The prospects of using radiation-chemical methods for processing of cellulose and other polysaccharides in industry and agriculture are considered. The bibliography includes 213 references.

  8. Investigations on the Chemical Degradation of Silver Gelatine Prints

    Directory of Open Access Journals (Sweden)

    Maha Ahmed ALI

    2012-06-01

    Full Text Available Photographs are considered composite objects with complex chemical and physical structures. Therefore they are more prone to damage as compared to other objects. Chemical degradation is by far the most common decay form found among photographic collections. This study investigates the chemical degradation of silver gelatin prints (DOP and the reaction of the image, silver, gelatin, and paper to accelerated aging, to the action of light, and oxidizing gases, in terms of their physical and chemical nature. The test materials used are properly washed and poorly washed grayscale, black-and-white processed images on photographic paper (Black & White Photographic Paper BH 0 Bromofort 6P0661 Tropical from Forte Photochemical Company Vác, Hungary. After exposure, the results were studied by means of visual inspection, amino acid analyzer, Fourier transform infrared and transmission electron microscope. The results were compared with those of the control samples. Our study revealed that the image, silver, gelatin and photographic paper are greatly affected by oxidizing agents and that the effect increased if the photographic prints were inadequately washed at the time of their processing. Furthermore, our results indicated that an increased amount of ammonia and amino acid in the silver gelatin print is a reliable indicator of the degradation of its gelatine emulsion.

  9. Degradation of chitosan by synergetic treatment of irradiation and chemical

    International Nuclear Information System (INIS)

    The degradation of solid state chitosan by irradiation at solid state and synergetic method were investigated in this paper. Four factors which affect the degradation effect of chitosan: irradiation, H2O2 concentration, the ratio of solvent and solute (volum/weight), acetic acid were analyzed. The first three were measured by multiple comparisons of the different level and variance analysis, and infrared spectroscopy was employed to analyze check the degradation products. It is concluded that chitosan's viscosity, and average molecular weight was decreased from 8.7 x 105 to 104 at the condition of 15% H2O2, HAc1.5%, 4:1 H2O2 solution/chitosan, 110 kGy irradiation, and the chemical structure of treat chitosan products was almost no changed. (authors)

  10. Chemical degradation mechanisms of membranes for alkaline membrane fuel cells

    International Nuclear Information System (INIS)

    Chemical degradation mechanisms of membranes for alkaline membrane fuel cells have been investigated using density functional theory (DFT). We have elucidated that the aryl-ether moiety of membranes is one of the weakest site against attack of hydroxide ions. The results of DFT calculations for hydroxide initiated aryl-ether cleavage indicated that the aryl-ether cleavage occurred prior to degradation of cationic functional group. Such a weak nature of the aryl-ether group arises from the electron deficiency of the aryl group as well as the low bond dissociation energy. The DFT results suggests that removal of the aryl-ether group in the membrane should enhance the stability of membranes under alkaline conditions. In fact, an ether fee poly(phenylene) membrane exhibits excellent stability against the attack from hydroxide ions

  11. Chemical degradation mechanisms of membranes for alkaline membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Choe, Yoong-Kee [National Institute of Advanced Industrial Science and Technology, Umezono 1-1-1, Tsukuba (Japan); Henson, Neil J.; Kim, Yu Seung [Los Alamos National Laboratory, Los Alamos, NM (United States)

    2015-12-31

    Chemical degradation mechanisms of membranes for alkaline membrane fuel cells have been investigated using density functional theory (DFT). We have elucidated that the aryl-ether moiety of membranes is one of the weakest site against attack of hydroxide ions. The results of DFT calculations for hydroxide initiated aryl-ether cleavage indicated that the aryl-ether cleavage occurred prior to degradation of cationic functional group. Such a weak nature of the aryl-ether group arises from the electron deficiency of the aryl group as well as the low bond dissociation energy. The DFT results suggests that removal of the aryl-ether group in the membrane should enhance the stability of membranes under alkaline conditions. In fact, an ether fee poly(phenylene) membrane exhibits excellent stability against the attack from hydroxide ions.

  12. Combined Chemical Activation and Fenton Degradation to Convert Waste Polyethylene into High-Value Fine Chemicals.

    Science.gov (United States)

    Chow, Cheuk-Fai; Wong, Wing-Leung; Ho, Keith Yat-Fung; Chan, Chung-Sum; Gong, Cheng-Bin

    2016-07-01

    Plastic waste is a valuable organic resource. However, proper technologies to recover usable materials from plastic are still very rare. Although the conversion/cracking/degradation of certain plastics into chemicals has drawn much attention, effective and selective cracking of the major waste plastic polyethylene is extremely difficult, with degradation of C-C/C-H bonds identified as the bottleneck. Pyrolysis, for example, is a nonselective degradation method used to crack plastics, but it requires a very high energy input. To solve the current plastic pollution crisis, more effective technologies are needed for converting plastic waste into useful substances that can be fed into the energy cycle or used to produce fine chemicals for industry. In this study, we demonstrate a new and effective chemical approach by using the Fenton reaction to convert polyethylene plastic waste into carboxylic acids under ambient conditions. Understanding the fundamentals of this new chemical process provides a possible protocol to solve global plastic-waste problems. PMID:27168079

  13. Coupling between chemical degradation and mechanical behaviour of leached concrete

    International Nuclear Information System (INIS)

    This work is in the context of the long term behavior of concrete employed in radioactive waste disposal. The objective is to study the coupled chemo-mechanical modelling of concrete. In the first part of this contribution, experimental investigations are described where the effects of the calcium leaching process of concrete on its mechanical properties are highlighted. An accelerated method has been chosen to perform this leaching process by using an ammonium nitrate solution. In the second part, we present a coupled phenomenological chemo-mechanical model that represents the degradation of concrete materials. On one hand, the chemical behavior is described by the simplified calcium leaching approach of cement paste and mortar. Then a homogenization approach using the asymptotic development is presented to take into account the influence of the presence of aggregates in concrete. And on the other hand, the mechanical part of the modelling is given. Here continuum damage mechanics is used to describe the mechanical degradation of concrete. The growth of inelastic strains observed during the mechanical tests is describes by means of a plastic like model. The model is established on the basis of the thermodynamics of irreversible processes framework. The coupled nonlinear problem at hand is addressed within the context of the finite element method. Finally, numerical simulations are compared with the experimental results for validation. (author)

  14. Thermal and chemical degradation of inorganic membrane materials. Topical report

    Energy Technology Data Exchange (ETDEWEB)

    Krishnan, G.N.; Sanjurjo, A.; Wood, B.J.; Lau, K.H.

    1994-04-01

    This report describes the results of a literature review to evaluate the long-term thermal and chemical degradation of inorganic membranes that are being developed to separate gaseous products produced by the gasification or combustion of coal in fixed-, fluidized-, and entrained-bed gasifiers, direct coal-fired turbines, and pressurized-fluidized-bed combustors. Several impurities, such as H{sub 2}S, NH{sub 3}, SO{sub 2}, NO{sub x}, and trace metal compounds are generated during coal conversion, and they must be removed from the coal gas or the combustor flue gas to meet environmental standards. The use of membranes to separate these noxious gases is an attractive alternative to their removal by sorbents such as zinc titanate or calcium oxide. Inorganic membranes that have a high separation efficiency and exhibit both thermal and chemical stability would improve the economics of power generation from coal. The U.S. Department of Energy is supporting investigations to develop inorganic membranes for separating hydrogen from coal gas streams and noxious impurities from hot coal- and flue-gas streams. Membrane materials that have been investigated in the past include glass (silica), alumina, zirconia, carbon, and metals (Pd and Pt).

  15. A new way for chemical degradation of plastic by natural volatile constituents of Ledum palustre

    Institute of Scientific and Technical Information of China (English)

    XIU Zhilong; ZHU Xiuling; ZHANG Daijia; YIN Jianzhong; WANG Dehe; AN Lijia

    2003-01-01

    A novel phenomenon of degradation of polypropylene plastic by volatile constituents of Ledum palustre is reported in this study. The characteristic of degradation is described by tensile strength, melting point, and scanning electron micrographs as well as optical micrographs. The chemical composition of volatile oil of Ledum palustre is analyzed by gas chrography and mass spectrometry. The mechanism of degradation and problems needed to be solved are also discussed.

  16. Atrazine degradation using chemical-free process of USUV: Analysis of the micro-heterogeneous environments and the degradation mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Xu, L.J., E-mail: xulijie827@gmail.com [Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong); Chu, W., E-mail: cewchu@polyu.edu.hk [Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong); Graham, Nigel, E-mail: n.graham@imperial.ac.uk [Department of Civil and Environmental Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom)

    2014-06-30

    Graphical abstract: - Highlights: • Two chemical-free AOP processes are combined to enhance atrazine degradation. • ATZ degradation in sonophotolytic process was analyzed using a previous proposed model. • The micro-bubble/liquid heterogeneous environments in sonolytic processes were investigated. • The salt effects on different sonolytic processes were examined. • ATZ degradation mechanisms were investigated and pathways were proposed. - Abstract: The effectiveness of sonolysis (US), photolysis (UV), and sonophotolysis (USUV) for the degradation of atrazine (ATZ) was investigated. An untypical kinetics analysis was found useful to describe the combined process, which is compatible to pseudo first-order kinetics. The heterogeneous environments of two different ultrasounds (20 and 400 kHz) were evaluated. The heterogeneous distribution of ATZ in the ultrasonic solution was found critical in determining the reaction rates at different frequencies. The presence of NaCl would promote/inhibit the rates by the growth and decline of “salting out” effect and surface tension. The benefits of combining these two processes were for the first time investigated from the aspect of promoting the intermediates degradation which were resistant in individual processes. UV caused a rapid transformation of ATZ to 2-hydroxyatrazine (OIET), which was insensitive to UV irradiation; however, US and USUV were able to degrade OIET and other intermediates through • OH attack. On the other hand, UV irradiation also could promote radical generation via H{sub 2}O{sub 2} decomposition, thereby resulting in less accumulation of more hydrophilic intermediates, which are difficult to degradation in the US process. Reaction pathways for ATZ degradation by all three processes are proposed. USUV achieved the greatest degree of ATZ mineralization with more than 60% TOC removed, contributed solely by the oxidation of side chains. Ammeline was found to be the only end-product in both US

  17. Preliminary experimental studies on the chemical and radiation degradation of combustible plutonium contaminated material

    International Nuclear Information System (INIS)

    The chemical and radiation degradation of combustible plutonium contaminated material (PCM) in a cement matrix has been investigated. Experimental studies have been carried out to establish the influence of any water soluble chemical and radiation degradation products on the solubility of plutonium at high pHs. The influence of complexing agents (e.g. EDTA, citric acid), which may be present in wastes, on plutonium solubility has been assessed. The extent of sorption on cement in the presence of organic degradation products has been measured. (author)

  18. Chemical degradation of an uncrosslinked pure fluororubber in an alkaline environment

    DEFF Research Database (Denmark)

    Mitra, S.; Ghanbari-Siahkali, A.; Kingshott, P.;

    2004-01-01

    The chemical degradation of an uncrosslinked pure fluoroelastomer (FKM; Viton A) in an alkaline environment (10% NaOH and 80 degreesC) was investigated. Scanning electron microscopy images showed that on a microscopic level, significant degradation substantially increased the surface roughness...... these species ultimately recombined to form crosslinks, as evidenced by the increase in the gel fraction and surface hardness (Shore A). The pronounced effect of chemical degradation through a reduction in the thermal stability of the pure FKM rubber upon exposure was also evident from thermogravimetric...

  19. Contaminant degradation in physically and chemically heterogeneous aquifers.

    Science.gov (United States)

    Cunningham, Jeffrey A; Fadel, Ziad J

    2007-12-01

    This paper examines the importance of the correlation between hydraulic conductivity (K) and degradation rate constant (k) during the transport of reactive contaminants in heterogeneous aquifers. We simulated reactive transport in an ensemble of two-dimensional heterogeneous aquifers. Two sets of transport simulations were conducted: one in which a perfect positive correlation was assumed between ln(K) and ln(k), and one in which a perfect negative correlation was assumed. We found that the sign of the correlation has important consequences for the contaminant transport. Qualitatively, a negative correlation leads to significantly more pronounced "fingering" of the contaminant plume than does a positive correlation, with potentially important consequences for downgradient receptors. Quantitatively, the expected behavior (as quantified by the contaminant mass remaining in the aquifer) is statistically different between the positive and negative cases: on average, more contaminant mass persists when K and k are negatively correlated. Also, the negative correlation leads to more variability between realizations of the ensemble, whereas a positive correlation induces relatively little variability between realizations. We discuss the implications of these findings for the management of contaminated aquifers. PMID:17854951

  20. Physical and chemical composition and in situ degradability of macauba palm cake and leaves

    OpenAIRE

    Vanda Patrícia Barros Ferreira; Rosana Aparecida Possenti; Patrícia Brás; Ailton Marques Piza; Joaquim Adelino Azevedo Filho

    2013-01-01

    Macauba palm coconuts are rich in essential nutrients for animal feed formulation and after oil extraction, a large amount of residual biomass is produced, which must be used rationally to environmental preservation. This study aimed to determine the nutritional value of macauba palm (Acrocomia aculeata), cake and leaves, for its physical and chemical composition, dry matter (DM) in vitro digestibility (IVD) and in situ degradability. The test of in situ degradability was done using three rum...

  1. State of chemical modeling modules for the degradation of concrete and cements

    Energy Technology Data Exchange (ETDEWEB)

    Meike, A.

    1997-04-15

    This report describes the conceptual framework upon which modeling activities will be needed to predict the chemistry of water in contact with concrete and its degradation products cover a broad area, from developing databases for existing abiotic codes, to developing codes that can simulate the chemical impact of microbial activities at a level of sophistication equivalent to that of the abiotic modeling codes, and ultimately, to simulating drift-scale chemical systems in support of hydrological, geochemical,a nd engineering efforts.

  2. Selective chemical degradation of kerogen from Nenjiang Formation of the southern Songliao Basin

    Institute of Scientific and Technical Information of China (English)

    XIONG; YongQiang; WANG; YongQuan; WANG; YanMei

    2007-01-01

    A sequential selective chemical degradation has been performed on the kerogen from the Nenjiang Formation of the southern Songliao Basin by using a series of mild chemical degradations (alkaline hydrolysis, cleavage of ether-bonds and sulfur-bonds, and ruthenium tetroxide (RuO4) oxidation). Subsequently, the GC-MS analyses are carried out on different degradation products. The results show that chemical degradations can release a great number of GC/MS-determinable biomarkers from insoluble kerogen, such as, alkaline hydrolysis products mainly comprise n-alkanes, fatty acids and alkanols; thiophene compounds are predominantly ether-bound to kerogen matrix; the products from the cleavage of sulfur-sulfur and sulfur-carbon bonds in the kerogen include fatty acids, alkanols and some n-alkanes with high carbon numbers; RuO4 oxidation products are predominantly monocarboxylic acids and α,ω-dicarboxylic acids. The distributions of main degradation products indicate that organic matter in this kerogen is predominantly derived from algae and bacteria, and that small amounts of high plant-derived organic matter are possibly combined into kerogen matrix at the late stage by sulfur bonds and other means. This study will provide an important approach for further discussing sources of organic matter in source rocks and their depositional paleoenvironments.

  3. Influence of enzyme and chemical adsorption on the thermal degradation path for eucalyptus pulp

    International Nuclear Information System (INIS)

    Highlights: ► Enzymes and chemicals adsorption changes thermal degradation path of cellulose. ► Adsorptions on pulp fibres increase their amorphous cellulose content. ► Charring/volatilization ratio of pulp is affected by adsorptions. - Abstract: Changes in thermal degradation path of eucalyptus pulp support enzymes (laccase from Trametes villosa) and chemicals (Tris–HCl or tartrate–tartaric buffer) adsorption on cellulose during biobleaching, thereby increasing cellulose amount that degrades at low temperature and decreasing the apparent crystallinity (ApC) of cellulose crystallites. Changes in ApC, which can be assessed by thermogravimetric analysis —but not X-ray diffraction spectroscopy—affect cellulose volatilization; thus, the higher ApC is, the lower is char production and the higher the volatilization temperature. A linear relationship between ApC and the volatilization/charring ratio (V/C) was observed in this work.

  4. Degradation of non-vulcanized natural rubber - renewable resource for fine chemicals used in polymer synthesis

    Directory of Open Access Journals (Sweden)

    Alexander Fainleib

    2013-01-01

    Full Text Available In the current scenario, there is growing interest in the products of degradation of rubber (natural and synthetic for specific applications in different industry sectors, whose benefits in replacing conventionally used products are mainly related to sustainability. Since the degradation products of rubber can be used in different areas, several research groups may have the interest aroused by these products, but are not familiar with the aspects related to the chemical behavior of rubber. This review aims to bring together the key information in the published literature on the degradation of natural rubber, emphasizing metatheses reactions, oxidative damage and splitting of the double bond, in order to serve as a reference source for researchers from different fields interested in obtaining such kind of products. The structures and properties as well as additional chemical transformations resulting in oligomers of isoprene, functionalised oligomers and polymers based on both are also described.

  5. Chemical composition and cell wall polysaccharide degradability of pith and rind tissues from mature maize internodes

    Science.gov (United States)

    Our study was undertaken to identify tissue-specific biochemical traits that may be targeted in breeding programs for improving forage digestibility. We compared cell wall chemical composition and 24- and 96-h in vitro degradabilities in separated pith and rind tissues from six maize inbred lines. A...

  6. Gray box modeling of MSW degradation: Revealing its dominant (bio)chemical mechanism

    NARCIS (Netherlands)

    Van Turnhout, A.G.; Heimovaara, T.J.; Kleerebezem, R.

    2013-01-01

    In this paper we present an approach to describe organic degradation within immobile water regions of Municipal Solid Waste (MSW) landfills which is best described by the term “gray box” model. We use a simplified set of dominant (bio)chemical and physical reactions and realistic environmental condi

  7. Finding Hidden Chemistry in Ancient Egyptian Artifacts: Pigment Degradation Taught in a Chemical Engineering Course

    Science.gov (United States)

    Gime´nez, Javier

    2015-01-01

    The main objective of this work was to show the application of the study of ancient technology and science on teaching (and learning) chemistry in Chemical Engineering Undergraduate studies. Degradation patterns of pigments used in Ancient Egypt were incorporated in the syllabus of the course entitled "Technological and Scientific…

  8. Lifetimes of organic photovoltaics: Combining chemical and physical characterisation techniques to study degradation mechanisms

    DEFF Research Database (Denmark)

    Norrman, K.; Larsen, N.B.; Krebs, Frederik C

    2006-01-01

    Degradation mechanisms of a photovoltaic device with an Al/C-60/C-12-PSV/PEDOT:PSS/ITO/glass geometry was studied using a combination of in-plane physical and chemical analysis techniques: TOF-SIMS, AFM, SEM, interference microscopy and fluorescence microscopy. A comparison was made between...

  9. Finding hidden chemistry in ancient egyptian artifacts: Pigment degradation taught in a chemical engineering course

    OpenAIRE

    Giménez Izquierdo, Francisco Javier

    2015-01-01

    The main objective of this work was to show the application of the study of ancient technology and science on teaching (and learning) chemistry in Chemical Engineering Undergraduate studies. Degradation patterns of pigments used in Ancient Egypt were incorporated in the syllabus of the course entitled

  10. Improving ruminal degradability and energetic values of bamboo shoot shell using chemical treatments.

    Science.gov (United States)

    Zhao, Liping; Ren, Liping; Zhou, Zhenming; Meng, Qingxiang; Huo, Yunlong; Wang, Fei

    2016-07-01

    This study evaluated effects of different treatments on nutritive value of bamboo shoot shell (BSS). Five treatments were sun-drying (control), ammoniation (5%/dry matter (DM) urea), Ca(OH)2 (4%/DM calcium hydroxide), NaOH (4%/DM sodium hydroxide), and AHP (4%/DM sodium hydroxide plus 1%/DM hydrogen peroxide). The results showed that chemical composition of BSS was greatly changed by chemicals (P chemical treatments significantly reduced neutral detergent fiber (NDF) content except AHP (P chemical treatments (P Chemical treatments greatly improved effective degradability (ED) of DM (P chemical treatments greatly improved nutritive value of BSS with highest value obtained from ammoniation, followed by strong alkalization, alkaline hydrogen peroxide and modest alkalization.

  11. In situ chemical degradation of DNAPLS in contaminated soils and sediments

    Energy Technology Data Exchange (ETDEWEB)

    Gates, D.D.; Korte, N.E.; Siegrist, R.L. [Oak Ridge National Lab., TN (United States)

    1996-08-01

    An emerging approach to in situ treatment of organic contaminants is chemical degradation. The specific processes discussed in this chapter are in situ chemical oxidation using either hydrogen peroxide (H{sub 2}O{sub 2}) or potassium permanganate (KMnO{sub 4}) and in situ dechlorination of halogenated hydrocarbons using zero-valence base metals such as iron. These technologies are primarily chemical treatment processes, where the treatment goal is to manipulate the chemistry of the subsurface environment in such a manner that the contaminants of interest are destroyed and/or rendered non-toxic. Chemical properties that can be altered include pH, ionic strength, oxidation and reduction potential, and chemical equilibria. In situ contaminant destruction processes alter or destroy contaminants in place and are typically applied to compounds that can be either converted to innocuous species such as CO{sub 2} and water, or can be degraded to species that are non-toxic or amenable to other in situ processes (i.e., bioremediation). With in situ chemical oxidation, the delivery and distribution of chemical reagents are critical to process effectiveness. In contrast, published approaches for the use of zero valence base metals suggest passive approaches in which the metals are used in a permeable reaction wall installed in situ in the saturated zone. Both types of processes are receiving increasing attention and are being applied both in technology demonstration and as final solutions to subsurface contaminant problems. 43 refs., 9 figs., 1 tab.

  12. Coupling between chemical degradation and mechanical behaviour of leached concrete; Couplage degradation chimique - comportement en compression du beton

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, V.H

    2005-10-15

    This work is in the context of the long term behavior of concrete employed in radioactive waste disposal. The objective is to study the coupled chemo-mechanical modelling of concrete. In the first part of this contribution, experimental investigations are described where the effects of the calcium leaching process of concrete on its mechanical properties are highlighted. An accelerated method has been chosen to perform this leaching process by using an ammonium nitrate solution. In the second part, we present a coupled phenomenological chemo-mechanical model that represents the degradation of concrete materials. On one hand, the chemical behavior is described by the simplified calcium leaching approach of cement paste and mortar. Then a homogenization approach using the asymptotic development is presented to take into account the influence of the presence of aggregates in concrete. And on the other hand, the mechanical part of the modelling is given. Here continuum damage mechanics is used to describe the mechanical degradation of concrete. The growth of inelastic strains observed during the mechanical tests is describes by means of a plastic like model. The model is established on the basis of the thermodynamics of irreversible processes framework. The coupled nonlinear problem at hand is addressed within the context of the finite element method. Finally, numerical simulations are compared with the experimental results for validation. (author)

  13. Performance of the In Situ Microcosm Technique for Measuring the Degradation of Organic Chemicals in Aquifers

    DEFF Research Database (Denmark)

    Nielsen, Per H.; Christensen, Thomas Højlund; Albrechtsen, Hans-Jørgen

    1996-01-01

    An in situ microcosm (ISM) consists of a stainless steel cylinder isolating about 2 L of the aquifer and is equipped with valves allowing for loading and sampling from the ground surface. During the last five years, this technique has been used frequently to study the degradation of organic...... chemicals in polluted and pristine aquifers representing different redox environments. The ISM technique has great potential for providing field-relevant degradation potentials and rate constants, but care must be taken in using the equipment and interpreting the results. This paper provides details...

  14. Thermal/chemical degradation of ceramic cross-flow filter materials

    Energy Technology Data Exchange (ETDEWEB)

    Alvin, M.A.; Lane, J.E.; Lippert, T.E.

    1989-11-01

    This report summarizes the 14-month, Phase 1 effort conducted by Westinghouse on the Thermal/Chemical Degradation of Ceramic Cross-Flow Filter Materials program. In Phase 1 expected filter process conditions were identified for a fixed-bed, fluid-bed, and entrained-bed gasification, direct coal fired turbine, and pressurized fluidized-bed combustion system. Ceramic cross-flow filter materials were also selected, procured, and subjected to chemical and physical characterization. The stability of each of the ceramic cross-flow materials was assessed in terms of potential reactions or phase change as a result of process temperature, and effluent gas compositions containing alkali and fines. In addition chemical and physical characterization was conducted on cross-flow filters that were exposed to the METC fluid-bed gasifier and the New York University pressurized fluidized-bed combustor. Long-term high temperature degradation mechanisms were proposed for each ceramic cross-flow material at process operating conditions. An experimental bench-scale test program is recommended to be conducted in Phase 2, generating data that support the proposed cross-flow filter material thermal/chemical degradation mechanisms. Papers on the individual subtasks have been processed separately for inclusion on the data base.

  15. Chemical constituents of the lichen, Candelaria concolor: a complete NMR and chemical degradative investigation.

    Science.gov (United States)

    Dias, Daniel A; Urban, Sylvia

    2009-01-01

    A detailed chemical and spectroscopic investigation of the terrestrial lichen Candelaria concolor has yielded several lichenic metabolites belonging to the pulvinic acid series, as well as several depside derivatives including pulvinic dilactone (1), vulpinic acid (4) and calycin (5). The chemical transformation of 1 to pulvinic acid (3) is reported for the first time, as is the conversion of atranorin (6) to 5-chloroatranorin (7) and then finally to 5,5'-dichloroatranorin (8) under very mild conditions. Also presented is the complete 1D and 2D NMR assignment for compounds 1, 3, 4, 5 and 8, including partial NMR chemical shift assignments for the unstable depside (7). Previously, these metabolites had only been partially assigned by NMR spectroscopy. PMID:19521906

  16. Combined treatment using chemical oxidation and radiation for enhancement degradation of chitosan

    International Nuclear Information System (INIS)

    Combined treatment using chemical oxidation and radiation has been considered for enhancement of chitosan degradation. The oxidative reagent was chosen to be hydrogen peroxide from heterogeneous reaction. Optimal conditions of concentration, temperature, pH were also determined. Characteristics of chitosan products were investigated by measurements of proton nuclear magnetic resonance spectroscopy (1HNMR), infrared spectroscopy (IR), viscosity average molecular weight (MW), ultraviolet spectrophotometry (UV), thermogravimetry analysis (TGA) and X-ray diffraction (XRD). (author)

  17. Gray box modeling of MSW degradation: Revealing its dominant (bio)chemical mechanism

    OpenAIRE

    Van Turnhout, A.G.; Heimovaara, T.J.; Kleerebezem, R.

    2013-01-01

    In this paper we present an approach to describe organic degradation within immobile water regions of Municipal Solid Waste (MSW) landfills which is best described by the term “gray box” model. We use a simplified set of dominant (bio)chemical and physical reactions and realistic environmental conditions. All equations, relationships and inhibitions are based on semi-empirical or fundamental relationships which have proven to be applicable in the peer reviewed literature. As much as possible ...

  18. Optimization of integrated chemical-biological degradation of a reactive azo dye using response surface methodology

    Energy Technology Data Exchange (ETDEWEB)

    Sudarjanto, Gatut [Advanced Wastewater Management Centre, The University of Queensland, Qld 4072 (Australia); Keller-Lehmann, Beatrice [Advanced Wastewater Management Centre, The University of Queensland, Qld 4072 (Australia); Keller, Jurg [Advanced Wastewater Management Centre, The University of Queensland, Qld 4072 (Australia)]. E-mail: j.keller@awmc.uq.edu.au

    2006-11-02

    The integrated chemical-biological degradation combining advanced oxidation by UV/H{sub 2}O{sub 2} followed by aerobic biodegradation was used to degrade C.I. Reactive Azo Red 195A, commonly used in the textile industry in Australia. An experimental design based on the response surface method was applied to evaluate the interactive effects of influencing factors (UV irradiation time, initial hydrogen peroxide dosage and recirculation ratio of the system) on decolourisation efficiency and optimizing the operating conditions of the treatment process. The effects were determined by the measurement of dye concentration and soluble chemical oxygen demand (S-COD). The results showed that the dye and S-COD removal were affected by all factors individually and interactively. Maximal colour degradation performance was predicted, and experimentally validated, with no recirculation, 30 min UV irradiation and 500 mg H{sub 2}O{sub 2}/L. The model predictions for colour removal, based on a three-factor/five-level Box-Wilson central composite design and the response surface method analysis, were found to be very close to additional experimental results obtained under near optimal conditions. This demonstrates the benefits of this approach in achieving good predictions while minimising the number of experiments required.

  19. Optimization of integrated chemical-biological degradation of a reactive azo dye using response surface methodology

    International Nuclear Information System (INIS)

    The integrated chemical-biological degradation combining advanced oxidation by UV/H2O2 followed by aerobic biodegradation was used to degrade C.I. Reactive Azo Red 195A, commonly used in the textile industry in Australia. An experimental design based on the response surface method was applied to evaluate the interactive effects of influencing factors (UV irradiation time, initial hydrogen peroxide dosage and recirculation ratio of the system) on decolourisation efficiency and optimizing the operating conditions of the treatment process. The effects were determined by the measurement of dye concentration and soluble chemical oxygen demand (S-COD). The results showed that the dye and S-COD removal were affected by all factors individually and interactively. Maximal colour degradation performance was predicted, and experimentally validated, with no recirculation, 30 min UV irradiation and 500 mg H2O2/L. The model predictions for colour removal, based on a three-factor/five-level Box-Wilson central composite design and the response surface method analysis, were found to be very close to additional experimental results obtained under near optimal conditions. This demonstrates the benefits of this approach in achieving good predictions while minimising the number of experiments required

  20. Degrading Endocrine Disrupting Chemicals from Wastewater by TiO Photocatalysis: A Review

    Directory of Open Access Journals (Sweden)

    Jin-Chung Sin

    2012-01-01

    Full Text Available Widespread concerns continue to be raised about the impacts of exposure to chemical compounds with endocrine disrupting activities. To date, the percolation of endocrine disrupting chemical (EDC effluent into the aquatic system remains an intricate challenge abroad the nations. With the innovation of advanced oxidation processes (AOPs, there has been a consistent growing interest in this research field. Hence, the aim of this paper is to focus one such method within the AOPs, namely, heterogeneous photocatalysis and how it is used on the abatement of EDCs, phthalates, bisphenol A and chlorophenols in particular, using TiO2-based catalysts. Degradation mechanisms, pathways, and intermediate products of various EDCs for TiO2 photocatalysis are described in detail. The effect of key operational parameters on TiO2 photocatalytic degradation of various EDCs is then specifically covered. Finally, the future prospects together with the challenges for the TiO2 photocatalysis on EDCs degradation are summarized and discussed.

  1. Chemical modification and degradation of atrazine in Medicago sativa through multiple pathways.

    Science.gov (United States)

    Zhang, Jing Jing; Lu, Yi Chen; Yang, Hong

    2014-10-01

    Atrazine is a member of the triazine herbicide family intensively used to control weeds for crop production. In this study, atrazine residues and its degraded products in alfalfa (Medicago sativa) were characterized using UPLC-TOF-MS/MS. Most of atrazine absorbed in plants was found as chemically modified derivatives like deisopropylated atrazine (DIA), dehydrogenated atrazine (DHA), or methylated atrazine (MEA), and some atrazine derivatives were conjugated through different functional groups such as sugar, glutathione, and amino acids. Interestingly, the specific conjugates DHA+hGSH (homoglutathione) and MEA-HCl+hGSH in alfalfa were detected. These results suggest that atrazine in alfalfa can be degraded through different pathways. The increased activities of glycosyltransferase and glutathione S-transferase were determined to support the atrazine degradation models. The outcome of the work uncovered the detailed mechanism for the residual atrazine accumulation and degradation in alfalfa and will help to evaluate whether the crop is suitable to be cultivated in the atrazine-polluted soil.

  2. The effects of the chemical and radiolytic degradation of asphalt on plutonium solubility

    International Nuclear Information System (INIS)

    The influence of alkaline degradation or radiolytic degradation of asphalt on plutonium solubility has been investigated. Asphalt has been contacted with water, sodium hydroxide solution or concrete leachate at 80 C for periods of up to approximately 2 years. Sodium nitrate was also present in some of the experiments. Plutonium solubilities were measured at pH 12 in the leachates and found to be less than 10-8 mol/dm3 for most degradations. Relatively low levels of Total Organic Carbon were measured in the leachates. Alpha radiolysis of asphalt in the presence of concrete and water has also been studied. Samples of asphalt were encapsulated in concrete after coating with the 238PuO2, crushed and leached at room temperature. The solubility of plutonium was measured in samples of the leachates after approximately 90 days and 180 days had elapsed. The results showed that the solubility of plutonium in the α-radiolysis leachates remained low and was in the range 2 x 10-11 to 8 x 10-9 mol/dm3. A consideration of these results, and data published elsewhere, suggests that chemical and radiolytic attack on asphalt or bitumen under anaerobic, alkaline conditions typical of a deep cementitious repository is unlikely to generate complexants for plutonium which are effective at high pH. Any enhancement of plutonium solubility is likely to be less significant than that arising from the degradation of some other organic materials

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

    Institute of Scientific and Technical Information of China (English)

    LI Mingyu; XIONG Lin; CHEN Yunyun; ZHANG Na; ZHANG Yuanming; YIN Hua

    2005-01-01

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

  4. Impact of lignin and carbohydrate chemical structures on degradation reactions during hardwood kraft pulping processes

    Directory of Open Access Journals (Sweden)

    Ricardo B. Santos

    2013-02-01

    Full Text Available Most studies aimed at determining rates of hardwood delignification and carbohydrate degradation have focused on understanding the behavior of a single wood species. Such studies tend to determine either the delignification rate or the rate of carbohydrate degradation without examining the potential interactions resulting from related variables. The current study provides a comprehensive evaluation on both lignin and carbohydrate degradation during kraft pulping of multiple hardwood species. The kraft delignification rates of E. urograndis, E. nitens, E. globulus, sweet gum, maple, red oak, red alder, cottonwood, and acacia were obtained. Furthermore, the kinetics of glucan, xylan, and total carbohydrate dissolution during the bulk phase of the kraft pulping process for the above species were also investigated. The wide ranges of delignification and carbohydrate degradation rates were correlated to wood chemical characteristics. It appears that the S/G ratio and lignin-carbohydrate-complexes (LCCs are the main characteristics responsible for the differences in kraft pulping performance among the hardwoods studied.

  5. A mathematical model for targeting chemicals to tissues by exploiting complex degradation

    Directory of Open Access Journals (Sweden)

    Grodzinsky Alan J

    2011-09-01

    Full Text Available Abstract Background In many biological and therapeutic contexts, it is highly desirable to target a chemical specifically to a particular tissue where it exerts its biological effect. In this paper, we present a simple, generic, mathematical model that elucidates a general method for targeting a chemical to particular tissues. The model consists of coupled reaction-diffusion equations to describe the evolution within the tissue of the concentrations of three chemical species: a (concentration of free chemical, b (binding protein and their complex, c (chemical bound to binding protein. We assume that all species are free to diffuse, and that a and b undergo a reversible reaction to form c. In addition, the complex, c, can be broken down by a process (e.g. an enzyme in the tissue that results in the release of the chemical, a, which is then free to exert its biological action. Results For simplicity, we consider a one-dimensional geometry. In the special case where the rate of complex formation is small (compared to the diffusion timescale of the species within the tissue the system can be solved analytically. This analytic solution allows us to show how the concentration of free chemical, a, in the tissue can be increased over the concentration of free chemical at the tissue boundary. We show that, under certain conditions, the maximum concentration of a can occur at the centre of the tissue, and give an upper bound on this maximum level. Numerical simulations are then used to determine how the behaviour of the system changes when the assumption of negligible complex formation rate is relaxed. Conclusions We have shown, using our mathematical model, how complex degradation can potentially be exploited to target a chemical to a particular tissue, and how the level of the active chemical depends on factors such as the diffusion coefficients and degradation/production rates of each species. The biological significance of these results in terms of

  6. Mechanical and microstructural/chemical degradation of coating and substrate in gas turbine blade

    Energy Technology Data Exchange (ETDEWEB)

    Sugita, Y.; Ito, M. [Chubu Electric Power Co. Inc., Nagoya (Japan); Sakurai, S. [Hitachi Ltd., Ibaraki (Japan). Hitachi Research Lab.; Gold, C.R.; Bloomer, T.E.; Kameda, J. [Iowa State Univ. of Science and Technology, Ames, IA (United States). Center for Advanced Technology Development

    1995-12-31

    The mechanical property degradation (295--1223 K) and microstructural/chemical evolution of CoNiCrAlY coatings and superalloy (Rene 80) substrates in gas turbine blades operated in- service have been studied using a small punch (SP) testing technique and scanning Auger microprobe. In SP tests, coating cracks continuously and discretely propagated at 295 K and higher temperatures, respectively. The ductile-brittle transition temperature of the coatings was increased during long time exposure of gas turbine blades to oxidizing environments while that of the substrate did not change. The low cycle fatigue life of the coatings at 295 K was also reduced in-service. Oxidation and sulfur segregation near the coating surface were found to be major causes of the mechanical degradation of the coatings.

  7. Intracellular degradation of chemically functionalized carbon nanotubes using a long-term primary microglial culture model

    Science.gov (United States)

    Bussy, Cyrill; Hadad, Caroline; Prato, Maurizio; Bianco, Alberto; Kostarelos, Kostas

    2015-12-01

    Chemically functionalized carbon nanotubes (f-CNTs) have been used in proof-of-concept studies to alleviate debilitating neurological conditions. Previous in vivo observations in brain tissue have suggested that microglia - acting as resident macrophages of the brain - play a critical role in the internalization of f-CNTs and their partial in situ biodegradation following a stereotactic administration in the cortex. At the same time, several reports have indicated that immune cells such as neutrophils, eosinophils and even macrophages could participate in the processing of carbon nanomaterials via oxidation processes leading to degradation, with surface properties acting as modulators of CNT biodegradability. In this study we questioned whether degradability of f-CNTs within microglia could be modulated depending on the type of surface functionalization used. We investigated the kinetics of degradation of multi-walled carbon nanotubes (MWNTs) functionalized via different chemical strategies that were internalized within isolated primary microglia over three months. A cellular model of rat primary microglia that can be maintained in cell culture for a long period of time was first developed. The Raman structural signature of the internalized f-CNTs was then studied directly in cells over a period of up to three months, following a single exposure to a non-cytotoxic concentration of three different f-CNTs (carboxylated, aminated and both carboxylated and aminated). Structural modifications suggesting partial but continuous degradation were observed for all nanotubes irrespective of their surface functionalization. Carboxylation was shown to promote more pronounced structural changes inside microglia over the first two weeks of the study.Chemically functionalized carbon nanotubes (f-CNTs) have been used in proof-of-concept studies to alleviate debilitating neurological conditions. Previous in vivo observations in brain tissue have suggested that microglia - acting as

  8. Quantification and Remediation of Soil Chemical Degradation in Tropical Australia,China and Thailand

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Soil and land degradation in the tropics can be identified and described in terms of physical, chemical,and biological changes from its pristine state brought about by natural and anthropogenic influences. Acharacteristic of these ecosystems is their capacity to recycle nutrients through soil organic matter (SOM).Following disturbance through changed land management, SOM is rapidly mineralized and there is a cor-responding decline in fertility and the variable charge component of the cation exchange capacity. As theseecosystems are strongly dependent on SOM for their functionality, changed land use can have irreversible im-pacts on the productivity of these systems. The paper focuses on quantifying chemical degradation throughprinting. Using values taken from the fingerprint of an undisturbed soil, an index of chemical degradationimprove poor quality soils in their natural condition are discussed, such as the addition of natural clays andsilicated materials. Results are present to show the effect of each of the aforementioned strategies on surfacecharge characteristics and associated increases in plant productivity.

  9. Physical and chemical composition and in situ degradability of macauba palm cake and leaves

    Directory of Open Access Journals (Sweden)

    Vanda Patrícia Barros Ferreira

    2013-12-01

    Full Text Available Macauba palm coconuts are rich in essential nutrients for animal feed formulation and after oil extraction, a large amount of residual biomass is produced, which must be used rationally to environmental preservation. This study aimed to determine the nutritional value of macauba palm (Acrocomia aculeata, cake and leaves, for its physical and chemical composition, dry matter (DM in vitro digestibility (IVD and in situ degradability. The test of in situ degradability was done using three rumen fistulated cattle. Analytical determinations were performed in the laboratory of Animal Nutrition of Instituto de Zootecnia, Nova Odessa-SP, Brazil. Six replicates were used for each analytical determination and were calculated the standard error. Macauba cake chemically assessed showed a low protein content (CP 4.5% and high content of acid detergent fibre (ADF 39.7% and average levels of neutral detergent fibre (NDF 52.5%. ADF and NDF were the macauba palm cake majority fractions compared NDF and ADF (respectively of cocoa cake (37.6 and 45.5%, sunflower cake (28.2 and 38.4%, corn meal (11.3 and 20.2% and peanut cake (15.4 and 21.0. Macauba palm leaves had a good protein content (12.0% and fiber content comparable to tropical grass of good nutritional value. They can be used with no restriction on ruminants’ diets. The macauba palm cake high levels of lignin (16.5% justify the low dry matter IVD percentage (48%, while the leaves had 58%.of IVD. Macauba leaves total digestible nutrients (TDN 59.0% is similar to TDN usually observed for forages. Macauba cake can be considered (TDN = 64.0% similar to energetic food, due to the fat content (6.4%, however the high content of lignin (16.5% can limit its consumption. Macauba palm cake showed high ruminal degradability of DM and CP (fraction a = 51.3 and 59.9, respectively, while macauba palm leaves hah low solubility of DM and CP (fraction a = 3.18 and 5.28, respectively. Thus, the higher CP macauba leaves

  10. Effect of enzyme addition to forage at ensiling on silage chemical composition and NDF degradation characteristics

    DEFF Research Database (Denmark)

    Dehghani, Mohammad Reza; Weisbjerg, Martin Riis; Hvelplund, Torben;

    2012-01-01

    The effect of different exogenous fibrolytic enzymes added to forages at ensiling was examined for effect on chemical composition and in vitro NDF degradability characteristics of the resulting silage. Maize stover and lucerne were used to study effect on chemical composition in experiment 1......-glucanase and pectinase activity increased lactic acid and decreased butyric acid, ammonia and pH compared with control silage, and increased glucose concentration in lucerne silage. NDF concentration generally decreased due to enzyme treatment with glucanase, β-glucanase and xylanase activity and in vitro organic matter...... with treatment with individual enzymes. Enzyme mix with xylanase, glucanase and β-glucanase activities was effective for maize stover, whereas a mix containing pectinase activity was most effective for reducing pH in lucerne. Data from this study suggest that adding fibrolytic enzymes to forages at ensiling can...

  11. Monitoring chemical degradation of thermally cycled glass-fibre composites using hyperspectral imaging

    Science.gov (United States)

    Papadakis, V. M.; Müller, B.; Hagenbeek, M.; Sinke, J.; Groves, R. M.

    2016-04-01

    Nowadays, the application of glass-fibre composites in light-weight structures is growing. Although mechanical characterizations of those structures are commonly performed in testing, chemical changes of materials under stresses have not yet been well documented. In the present work coupon tests and Hyperspectral Imaging (HSI) have been used to categorise possible chemical changes of glass-fibre reinforced polymers (GFRP) which are currently used in the aircraft industry. HSI is a hybrid technique that combines spectroscopy with imaging. It is able to detect chemical degradation of surfaces and has already been successfully applied in a wide range of fields including astronomy, remote sensing, cultural heritage and medical sciences. GFRP specimens were exposed to two different thermal loading conditions. One thermal loading condition was a continuous thermal exposure at 120°C for 24h, 48 h and 96h, i.e. ageing at a constant temperature. The other thermal loading condition was thermal cycling with three different numbers of cycles (4000, 8000, 12000) and two temperature ranges (0°C to 120°C and -25°C to 95°C). The effects of both conditions were measured using both HSI and interlaminar shear (ILSS) tests. No significant changes of the physical properties of the thermally cycled GFRP specimens were detected using interlaminar shear strength tests and optical microscopy. However, when using HIS, differences of the surface conditions were detected. The results showed that the different thermal loading conditions could be successfully clustered in different colours, using the HSI linear unmixing technique. Each different thermal loading condition showed a different chemical degradation level on its surface which was indicated using different colours.

  12. Chemical degradation and toxicity reduction of 4-chlorophenol in different matrices by gamma-ray treatment

    Science.gov (United States)

    Kang, Sung-Wook; Shim, Seung-Bo; Park, Young-Kwon; Jung, Jinho

    2011-03-01

    Gamma-ray treatment of 4-chlorophenol (4-CP) in different matrices was studied in terms of both chemical degradation and toxicity reduction. Degradation of 4-CP in a complex effluent matrix was less efficient than that in ultrapure water. This is most likely due to the consumption of reactive radicals by matrix components, such as dissolved organic matter in effluents. The matrix effect caused much more profound changes in toxicity. Gamma-ray treatment of 4-CP in ultrapure water abruptly increased acute toxicity toward Daphnia magna while slightly decreased toxicity of 4-CP in effluent. In the presence of ZrO 2 catalyst, degradation of 4-CP as well as toxicity reduction was substantially improved mostly by adsorption of 4-CP onto the nanoparticles. It was found that benzoquinone, hydroquinone and 4-chlorocatechol were generated for ultrapure water sample while only 4-chlorocatechol was formed for effluent samples by gamma-ray treatment. As determined in this work, EC 50 values of benzoquinone (0.46 μM), hydroquinone (0.61 μM) and chlorocatechol (8.87 μM) were much lower than those of 4-CP (31.50 μM), explaining different toxicity changes of 4-CP in different matrices by gamma-ray treatment. The observed toxicity of gamma-ray treated 4-CP was well correlated with the one calculated from individual toxicity based on EC 50 value.

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

    Science.gov (United States)

    Matczuk, M; Obarski, N; Mojski, M

    2012-10-01

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

  14. Improving ruminal degradability and energetic values of bamboo shoot shell using chemical treatments.

    Science.gov (United States)

    Zhao, Liping; Ren, Liping; Zhou, Zhenming; Meng, Qingxiang; Huo, Yunlong; Wang, Fei

    2016-07-01

    This study evaluated effects of different treatments on nutritive value of bamboo shoot shell (BSS). Five treatments were sun-drying (control), ammoniation (5%/dry matter (DM) urea), Ca(OH)2 (4%/DM calcium hydroxide), NaOH (4%/DM sodium hydroxide), and AHP (4%/DM sodium hydroxide plus 1%/DM hydrogen peroxide). The results showed that chemical composition of BSS was greatly changed by chemicals (P AHP (P AHP. Ammoniation had higher (P = 0.03) ammonia-N concentration than the other four treatments. There were significant differences among all treatments on total volatile fatty acids (P = 0.03), propionate (P = 0.01), butyrate concentration (P < 0.01) and C2 /C3 ratio (P = 0.02). Chemical treatments greatly improved effective degradability (ED) of DM (P < 0.01) and ED of NDF (P = 0.06) and ADF (P = 0.07) numerically. Ammoniation got a higher ED of crude protein than control. In conclusion, all chemical treatments greatly improved nutritive value of BSS with highest value obtained from ammoniation, followed by strong alkalization, alkaline hydrogen peroxide and modest alkalization. PMID:26953064

  15. Accelerating the degradation of green plant waste with chemical decomposition agents.

    Science.gov (United States)

    Kejun, Sun; Juntao, Zhang; Ying, Chen; Zongwen, Liao; Lin, Ruan; Cong, Liu

    2011-10-01

    Degradation of green plant waste is often difficult, and excess maturity times are typically required. In this study, we used lignin, cellulose and hemicellulose assays; scanning electron microscopy; infrared spectrum analysis and X-ray diffraction analysis to investigate the effects of chemical decomposition agents on the lignocellulose content of green plant waste, its structure and major functional groups and the mechanism of accelerated degradation. Our results showed that adding chemical decomposition agents to Ficus microcarpa var. pusillifolia sawdust reduced the contents of lignin by 0.53%-11.48% and the contents of cellulose by 2.86%-7.71%, and increased the contents of hemicellulose by 2.92%-33.63% after 24 h. With increasing quantities of alkaline residue and sodium lignosulphonate, the lignin content decreased. Scanning electron microscopy showed that, after F. microcarpa var. pusillifolia sawdust was treated with chemical decomposition agents, lignocellulose tube wall thickness increased significantlyIncreases of 29.41%, 3.53% and 34.71% were observed after treatment with NaOH, alkaline residue and sodium lignosulphonate, respectively. Infrared spectroscopy showed that CO and aromatic skeleton stretching absorption peaks were weakened and the C-H vibrational absorption peak from out-of-plane in positions 2 and 6 (S units) (890-900 cm(-1)) was strengthened after F. microcarpa var. pusillifolia sawdust was treated with chemical decomposition agents, indicating a reduction in lignin content. Several absorption peaks [i.e., C-H deformations (asymmetry in methyl groups, -CH(3)- and -CH(2)-) (1450-1460 cm(-1)); Aliphatic C-H stretching in methyl and phenol OH (1370-1380 cm(-1)); CO stretching (cellulose and hemicellulose) (1040-1060 cm(-1))] that indicate the presence of a chemical bond between lignin and cellulose was reduced, indicating that the chemical bond between lignin and cellulose had been partially broken. X-ray diffraction analysis showed that Na

  16. Effect of chemical degradation on fluxes of reactive compounds – a study with a stochastic Lagrangian transport model

    Directory of Open Access Journals (Sweden)

    J. Rinne

    2012-06-01

    Full Text Available In the analyses of VOC fluxes measured above plant canopies, one usually assumes the flux above canopy to equal the exchange at the surface. Thus one assumes the chemical degradation to be much slower than the turbulent transport. We used a stochastic Lagrangian transport model in which the chemical degradation was described as first order decay in order to study the effect of the chemical degradation on above canopy fluxes of chemically reactive species. With the model we explored the sensitivity of the ratio of the above canopy flux to the surface emission on several parameters such as chemical lifetime of the compound, friction velocity, stability, and canopy density. Our results show that friction velocity and chemical lifetime affected the loss during transport the most. The canopy density had a significant effect if the chemically reactive compound was emitted from the forest floor. We used the results of the simulations together with oxidant data measured during HUMPPA-COPEC-2010 campaign at a Scots pine site to estimate the effect of the chemistry on fluxes of three typical biogenic VOCs, isoprene, α-pinene, and β-caryophyllene. Of these, the chemical degradation had a major effect on the fluxes of the most reactive species β-caryophyllene, while the fluxes of α-pinene were affected during nighttime. For these two compounds representing the mono- and sesquiterpenes groups, the effect of chemical degradation had also a significant diurnal cycle with the highest chemical loss at night. The different day and night time loss terms need to be accounted for, when measured fluxes of reactive compounds are used to reveal relations between primary emission and environmental parameters.

  17. Relating the Chemical Composition of Dissolved Organic Matter Draining Permafrost Soils to its Photochemical Degradation in Arctic Surface Waters.

    Science.gov (United States)

    Ward, C.; Cory, R. M.

    2015-12-01

    Thawing permafrost soils are expected to shift the chemical composition of DOM exported to and degraded in arctic surface waters. While DOM photo-degradation is an important component of the freshwater C cycle in the Arctic, the molecular controls on DOM photo-degradation remain poorly understood, making it difficult to predict how shifting chemical composition may alter DOM photo-degradation in arctic surface waters. To address this knowledge gap, we quantified the susceptibility of DOM draining the shallow organic mat and the deeper permafrost layer to complete photo-oxidation to CO₂ and partial photo-oxidation to compounds that remain in the DOM pool, and investigated changes in DOM chemical composition following sunlight exposure. DOM leached from the organic mat contained higher molecular weight, more oxidized and unsaturated aromatic species compared to permafrost DOM. Despite significant differences in initial chemical composition, permafrost and organic mat DOM had similar susceptibilities to complete photo-oxidation to CO₂. Concurrent losses of carboxyl moieties and shifts in chemical composition during photo-degradation indicated that carboxyl-rich tannin-like compounds in both DOM sources were likely photo-decarboxylated to CO₂. Permafrost DOM had a higher susceptibility to partial photo-oxidation compared to organic mat DOM, potentially due to a lower abundance of phenolic compounds that act as "antioxidants" and slow the oxidation of DOM. These results demonstrated how chemical composition controls the photo-degradation of DOM in arctic surface waters, and that DOM photo-degradation will likely remain an important component of the freshwater C budget in the Arctic with increased export of permafrost DOM to surface waters.

  18. Degradation of deicing chemicals affects the natural redox system in airfield soils.

    Science.gov (United States)

    Lissner, Heidi; Wehrer, Markus; Jartun, Morten; Totsche, Kai Uwe

    2014-01-01

    During winter operations at airports, large amounts of organic deicing chemicals (DIC) accumulate beside the runways and infiltrate into the soil during spring. To study the transport and degradation of DIC in the unsaturated zone, eight undisturbed soil cores were retrieved at Oslo airport, Norway, and installed as lysimeters at a nearby field site. Before snowmelt in 2010 and 2011, snow amended with a mix of the DICs propylene glycol (PG) and formate as well as bromide as conservative tracer was applied. Water samples were collected and analyzed until summer 2012. Water flow and solute transport varied considerably among the lysimeters but also temporally between 2010 and 2011. High infiltration rates during snowmelt resulted in the discharge of up to 51 and 82% PG in 2010 and 2011, respectively. The discharge of formate remained comparatively low, indicating its favored degradation even at freezing temperatures compared with PG. Manganese (Mn) and iron (Fe) were observed in the drainage in autumn owing to the anaerobic degradation of residual PG during summer. Our findings suggest that upper boundary conditions, i.e., snow cover and infiltration rate, and the extent of preferential flowpaths, control water flow and solute transport of bromide and PG during snowmelt. PG may therefore locally reach deeper soil regions where it may pose a risk for groundwater. In the long term, the use of DIC furthermore causes the depletion of potential electron acceptors and the transport of considerable amounts of Fe and Mn. To avoid an overload of the unsaturated zone with DIC and to maintain the natural redox system, the development of suitable remediation techniques is required. PMID:24062062

  19. Evaluating changes of transport properties of chemically degrading concrete using a coupled reactive transport model

    International Nuclear Information System (INIS)

    This paper presents a model to simulate chemical degradation of concrete due to leaching. The model considers simultaneously the multi-scale nature of concrete, a thermodynamic description of cement phases, and time-variable transport properties. It is implemented in the generic simulator HP1, which simulates the reactive transport in variably-saturated porous media. To illustrate the capabilities of the program, we simulate diffusive transport through concrete in contact with waters of different solution compositions (i.e., concentrations of major cations and anions and inorganic carbon contents) and use a homogenization scheme for up-scaling tortuosity. The simulations show the coupled effects between geochemical state variables, transport properties, and durability criteria for cementitious materials used in near-surface radioactive waste disposal facilities. (authors)

  20. Chemical degradation of trimethyl phosphate as surrogate for organo-phosporus pesticides on nanostructured metal oxides

    International Nuclear Information System (INIS)

    Nanostructured TiO2 and mixed oxides of Ti and Fe, Hf, In, Mn or Zr -were prepared by homogeneous hydrolysis of aqueous solution of metal sulphates with urea. The oxides were characterised by X-ray powder diffraction (XRD), scanning electron microscopy, particle size distribution, surface area and porosity. The oxide materials consists of a few nanometre primary crystals (mainly anatase) arranged in a few micrometre regular spherical agglomerates with specific surface area 133–511 m2 g−1. The FTIR diffuse spectroscopy was used for monitoring chemical degradation of trimethylphosphate (TMP) as a surrogate for organo-phosphorus pesticides under ambient and higher temperatures. Undoped TiO2 and Ti,Mn-mixed oxide were most active in cleavage (hydrolysis) of CH3O from TMP at room temperature and 100 °C. Cleavage of CH3O in the other studied mixed oxides was not complete until temperature exceeds the boiling point of TMP

  1. Assessment of insulation degradation of I and C cables from chemical and mechanical measurements

    International Nuclear Information System (INIS)

    Instrumentation and control (I and C) cables used in nuclear power plants (NPPs) are exposed to various deteriorative environmental effects during their operational lifetime. The factors consisting of long-term irradiation (at rather low dose rates, in the presence of oxygen), and enhanced temperature eventually result in insulation degradation. Monitoring of the actual state of the cable insulation and the prediction of their residual service life consist of the measurement of the properties that are directly proportional to the functionality of the cables (usually the elongation at break is used as the critical parameter). In view of this, accelerated thermal and radiation ageing of I and C cable insulation materials have been carried out and the degradation due to thermal and radiation ageing has been assessed using oxidation induction time (OIT) and oxidation induction temperature (OITp) measurements by differential scanning calorimetry (DSC). As elongation at break (EAB) is considered to be a benchmark characterization technique for polymeric materials, tensile tests have also been carried out on these cable materials to measure EAB for correlating with DSC findings. The scanning electron microscopy (SEM) performed on fresh and aged samples support relatively good correlation between chemical and mechanical properties. (author)

  2. Accurate quantitation of pentaerythritol tetranitrate and its degradation products using liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry

    NARCIS (Netherlands)

    Brust, H.; Asten, A. van; Koeberg, M.; Dalmolen, J.; Heijden, A.E.D.M. van der; Schoenmakers, P.

    2014-01-01

    After an explosion of pentaerythritol tetranitrate (PETN), its degradation products pentaerythritol trinitrate (PETriN), dinitrate (PEDiN) and mononitrate (PEMN) were detected using liquid chromatography-atmospheric-pressure chemical-ionization-mass spectrometry (LC-APCI-MS). Discrimination between

  3. Identification of chlorinated solvents degradation zones in clay till by high resolution chemical, microbial and compound specific isotope analysis

    DEFF Research Database (Denmark)

    Damgaard, Ida; Bjerg, Poul Løgstrup; Bælum, Jacob;

    2013-01-01

    subsampling of the clay till cores. The study demonstrates that an integrated approach combining chemical analysis, molecular microbial tools and compound specific isotope analysis (CSIA) was required in order to document biotic and abiotic degradations in the clay till system. © 2013 Elsevier B.V....

  4. Chemical degradation of trimethyl phosphate as surrogate for organo-phosporus pesticides on nanostructured metal oxides

    Energy Technology Data Exchange (ETDEWEB)

    Štengl, Václav, E-mail: stengl@iic.cas.cz; Henych, Jiří; Grygar, Tomáš; Pérez, Raúl

    2015-01-15

    Nanostructured TiO{sub 2} and mixed oxides of Ti and Fe, Hf, In, Mn or Zr -were prepared by homogeneous hydrolysis of aqueous solution of metal sulphates with urea. The oxides were characterised by X-ray powder diffraction (XRD), scanning electron microscopy, particle size distribution, surface area and porosity. The oxide materials consists of a few nanometre primary crystals (mainly anatase) arranged in a few micrometre regular spherical agglomerates with specific surface area 133–511 m{sup 2} g{sup −1}. The FTIR diffuse spectroscopy was used for monitoring chemical degradation of trimethylphosphate (TMP) as a surrogate for organo-phosphorus pesticides under ambient and higher temperatures. Undoped TiO{sub 2} and Ti,Mn-mixed oxide were most active in cleavage (hydrolysis) of CH{sub 3}O from TMP at room temperature and 100 °C. Cleavage of CH{sub 3}O in the other studied mixed oxides was not complete until temperature exceeds the boiling point of TMP.

  5. Soil chemical properties, organic reserves and root system of a degraded pasture associated introduction of legume

    Directory of Open Access Journals (Sweden)

    Carlos Eduardo Santos Fabrice

    2014-09-01

    Full Text Available The aim was to study the recovery of degraded pasture with the introduction of Stylosanthes macrocephala e capitata cv. Campo Grande on Brachiaria decumbens cv. Basilisk evaluating the levels N-total in roots, biomass, area, and length, diameter and root levels of macro and micronutrients in the soil. The experiment was conducted in the municipality of Andradina, São Paulo State, Brazil. The experimental design was a randomized block design in a split-plot (with and without phosphorus, with four replicates, forming the following treatments: control Brachiaria decumbens (CB, partial desiccation with 1.5 L ha-1 of glyphosate (DP, total desiccation with 3.0 L ha-1 of glyphosate (TD; tillage (T, soil scarification (S; harrowing rome (H and plowing + disking (PD. Treatments H and PD were sown by broadcasting and the other in the form of direct seeding. Recovery strategies of grazing signal grass showed significant differences between treatments only for the content of N-total, there were no differences in geometric characteristics of roots and root biomass. The contents of macro and micronutrients in the soil showed no significant differences between the strategies of recovery. Fertilization had a significant effect for P. The introduction of estilosantes Campo Grande accompanied by techniques such as drying and plowing + disking contributed to increases in the N-total levels in the root system. Forms of introduction of legumes did not change the soil chemical properties.

  6. Mass spectrometric study of selected precursors and degradation products of chemical warfare agents.

    Science.gov (United States)

    Papousková, Barbora; Bednár, Petr; Frysová, Iveta; Stýskala, Jakub; Hlavác, Jan; Barták, Petr; Ulrichová, Jitka; Jirkovský, Jaromír; Lemr, Karel

    2007-12-01

    Selected precursors and degradation products of chemical warfare agents namely N,N-dialkylaminoethane-2-ols, N,N-dialkylaminoethyl-2-chlorides and some of related N-quaternary salts were studied by means of electrospray ionization-multiple tandem mass spectrometry (ESI-MS(n)). Proposed structures were confirmed with accurate mass measurement. General fragmentation patterns of these compounds are discussed in detail and suggested processes are confirmed using deuterated standards. The typical processes are elimination of alkene, hydrogen chloride, or water, respectively. Besides, elimination of ethene from propyl chain under specific conditions was observed and unambiguously confirmed using exact mass measurement and labelled standard. The potential of mass spectrometry to distinguish the positional isomers occurring among the studied compounds is reviewed in detail using two different MS instruments (i.e. ion trap and hybrid quadrupole-time of flight (Q-TOF) analyzer). A new microcolumn liquid chromatography (microLC)/MS(n) method was designed for the cases where the resolution based solely on differences in fragmentation is not sufficient. Low retention of the derivatives on reversed phase (RP) was overcome by using addition of less typical ion pairing agent (1 mM/l, 3,5-dinitrobenzoic acid) to the mobile phase (mixture water : acetonitrile). PMID:18085550

  7. Nanomaterial based detection and degradation of biological and chemical contaminants in a microfluidic system

    Science.gov (United States)

    Jayamohan, Harikrishnan

    Monitoring and remediation of environmental contaminants (biological and chemical) form the crux of global water resource management. There is an extant need to develop point-of-use, low-power, low-cost tools that can address this problem effectively with minimal environmental impact. Nanotechnology and microfluidics have made enormous advances during the past decade in the area of biosensing and environmental remediation. The "marriage" of these two technologies can effectively address some of the above-mentioned needs. In this dissertation, nanomaterials were used in conjunction with microfluidic techniques to detect and degrade biological and chemical pollutants. In the first project, a point-of-use sensor was developed for detection of trichloroethylene (TCE) from water. A self-organizing nanotubular titanium dioxide (TNA) synthesized by electrochemical anodization and functionalized with photocatalytically deposited platinum (Pt/TNA) was applied to the detection. The morphology and crystallinity of the Pt/TNA sensor was characterized using field emission scanning electron microscope, energy dis- persive x-ray spectroscopy, and X-ray diffraction. The sensor could detect TCE in the concentrations ranging from 10 to 1000 ppm. The room-temperature operation capability of the sensor makes it less power intensive and can potentially be incorporated into a field-based sensor. In the second part, TNA synthesized on a foil was incorporated into a flow-based microfluidic format and applied to degradation of a model pollutant, methylene blue. The system was demonstrated to have enhanced photocatalytic performance at higher flow rates (50-200 muL/min) over the same microfluidic format with TiO2 nanoparticulate (commercial P25) catalyst. The microfluidic format with TNA catalyst was able to achieve 82% fractional conversion of 18 mM methylene blue in comparison to 55% in the case of the TiO2 nanoparticulate layer at a flow rate of 200 L/min. The microfluidic device was

  8. Dynamic three-dimensional micropatterned cell co-cultures within photocurable and chemically degradable hydrogels.

    Science.gov (United States)

    Sugiura, Shinji; Cha, Jae Min; Yanagawa, Fumiki; Zorlutuna, Pinar; Bae, Hojae; Khademhosseini, Ali

    2016-08-01

    In this paper we report on the development of dynamically controlled three-dimensional (3D) micropatterned cellular co-cultures within photocurable and chemically degradable hydrogels. Specifically, we generated dynamic co-cultures of micropatterned murine embryonic stem (mES) cells with human hepatocellular carcinoma (HepG2) cells within 3D hydrogels. HepG2 cells were used due to their ability to direct the differentiation of mES cells through secreted paracrine factors. To generate dynamic co-cultures, mES cells were first encapsulated within micropatterned photocurable poly(ethylene glycol) (PEG) hydrogels. These micropatterned cell-laden PEG hydrogels were subsequently surrounded by calcium alginate (Ca-Alg) hydrogels containing HepG2 cells. After 4 days, the co-culture step was halted by exposing the system to sodium citrate solution, which removed the alginate gels and the encapsulated HepG2 cells. The encapsulated mES cells were then maintained in the resulting cultures for 16 days and cardiac differentiation was analysed. We observed that the mES cells that were exposed to HepG2 cells in the co-cultures generated cells with higher expression of cardiac genes and proteins, as well as increased spontaneous beating. Due to its ability to control the 3D microenvironment of cells in a spatially and temporally regulated manner, the method presented in this study is useful for a range of cell-culture applications related to tissue engineering and regenerative medicine. Copyright © 2013 John Wiley & Sons, Ltd. PMID:24170301

  9. Dynamic three-dimensional micropatterned cell co-cultures within photocurable and chemically degradable hydrogels.

    Science.gov (United States)

    Sugiura, Shinji; Cha, Jae Min; Yanagawa, Fumiki; Zorlutuna, Pinar; Bae, Hojae; Khademhosseini, Ali

    2016-08-01

    In this paper we report on the development of dynamically controlled three-dimensional (3D) micropatterned cellular co-cultures within photocurable and chemically degradable hydrogels. Specifically, we generated dynamic co-cultures of micropatterned murine embryonic stem (mES) cells with human hepatocellular carcinoma (HepG2) cells within 3D hydrogels. HepG2 cells were used due to their ability to direct the differentiation of mES cells through secreted paracrine factors. To generate dynamic co-cultures, mES cells were first encapsulated within micropatterned photocurable poly(ethylene glycol) (PEG) hydrogels. These micropatterned cell-laden PEG hydrogels were subsequently surrounded by calcium alginate (Ca-Alg) hydrogels containing HepG2 cells. After 4 days, the co-culture step was halted by exposing the system to sodium citrate solution, which removed the alginate gels and the encapsulated HepG2 cells. The encapsulated mES cells were then maintained in the resulting cultures for 16 days and cardiac differentiation was analysed. We observed that the mES cells that were exposed to HepG2 cells in the co-cultures generated cells with higher expression of cardiac genes and proteins, as well as increased spontaneous beating. Due to its ability to control the 3D microenvironment of cells in a spatially and temporally regulated manner, the method presented in this study is useful for a range of cell-culture applications related to tissue engineering and regenerative medicine. Copyright © 2013 John Wiley & Sons, Ltd.

  10. Semiempirical Predictions of Chemical Degradation Reaction Mechanisms of CL-20 as Related to Molecular Structure

    Energy Technology Data Exchange (ETDEWEB)

    Qasim, Mohammad M.; Furey, John; Fredrickson, Herbert L.; Szecsody, Jim E.; Mcgrath, Chris J.; Bajpai, Rakesh

    2004-10-01

    Quantum mechanical methods and force field molecular mechanics were used to characterize cage cyclic nitramines and to predict environmental degradation mechanisms. Due to structural similarities it is predicted that, under homologous circumstances, the major environmental RDX degradation pathways should also be effective for CL-20 and similar cyclic nitramines.

  11. Radiation-chemical degradation of traces of trichloroethylene and perchloroethylene in drinking water

    International Nuclear Information System (INIS)

    The degradation caused by gamma irradiation of traces of trichloroethylene and perchloroethylene in certain water samples has been investigated over a wide range of concentrations. In general, the degradation is the slower, the higher the concentration of organic and inorganic substances (especially of nitrates) dissolved in the respective water. For pollutant concentrations up to about 500 ppb and for drinking water with rather low nitrate content (some ppm) the degradation follows a first-order rate law. For higher concentrations of pollutants or/and nitrates a much more complex behaviour is observed. In general, perchloroethylene is degraded slower than trichloroethylene. During degradation, organic chlorine is converted quantitatively to chloride ions. Unfortunately, as a side reaction nitrate is partially reduced to nitrite. Except for that, first rough estimates resulted in costs which seem to render such a process economically quite attractive. (orig.)

  12. Oxidative degradation of lignin by photochemical and chemical radical generating systems

    International Nuclear Information System (INIS)

    Oxidation of specifically radiolabeled 14C-lignins by UV/H2O2, Fenton's reagent, photosensitizing riboflavin, UV- and γ-irradiation was examined. In the presence of UV/H2O2, a hydroxyl radical (radicalOH) generating system, 14C-methoxy, 2-[14C-sidechain] and 14C-ring labeled lignin were rapidly and extensively degraded as measured by gel filtration of the reaction products on Sephadex LH-20. This suggested that exposure to radicalOH leads to rapid, nonspecific lignin degradation. Rapid degradation of 14C-methoxy, 2-[14C-sidechain] and 14C-ring labeled lignin also occurred in the presence of the radicalOH generating system, Fenton's reagent, confirming the primary role of radicalOH in these reactions. Photosensitizing riboflavin, also capable of effecting transformation of organic compounds via Type I hydrogen radical abstractions, caused extensive oxidative degradation of 14C-methoxy labeled lignin and significant degradation of 2-[14C-sidechain] and 14C-ring labeled lignin. In addition, UV- and γ-irradiation caused slower but extensive degradation of the polymers, probably via radical type mechanisms. All of these results indicate that radicalOH as well as organic radical generating systems are effective agents for the purpose of degrading this heterogeneous, optically inactive and random biopolymer. (author)

  13. Studies on degradation of glyphosate by several oxidative chemical processes: ozonation, photolysis and heterogeneous photocatalysis.

    Science.gov (United States)

    Assalin, Marcia R; De Moraes, Sandra G; Queiroz, Sonia C N; Ferracini, Vera L; Duran, Nelson

    2010-01-01

    Several different Advanced Oxidation Processes (AOPs) including ozonation at pH 6.5 and 10, photolysis and heterogeneous photocatalysis using TiO(2) as semiconductor and dissolved oxygen as electron acceptor were applied to study the degradation of glyphosate (N-phosphonomethyl glycine) in water. The degree of glyphosate degradation, the reactions kinetic and the formation of the major metabolite, aminomethyl phosphonic acid (AMPA), were evaluated. Ozonation at pH 10 resulted in the maximum mineralization of glyphosate. It was observed that under the experimental conditions used in this study the degradation of glyphosate followed the first-order kinetics. The half-life obtained for glyphosate degradation in the O(3)/pH 10 process was 1.8 minutes.

  14. The rim zone of cement based materials - barrier or fast lane for chemical degradation?

    International Nuclear Information System (INIS)

    This contribution focuses exemplarily on the chemical and mineralogical changes in the rim zone of cement paste samples exposed to different chloride solutions (NaCl, KCl, MgCl2 and CaCl2), to hard tap water and to demineralized water. The determination of the Ca(OH)2 and Mg(OH)2 content of the solid phases was performed by means of thermogravimetry with pulverized samples (TGA/SDTA 851, Mettler-Toledo). A potential relation between temperature and the time dependant development of the material due to reactive transport processes will also be addressed. The experiments with tap water showed that the contact between the cement paste samples and hard tap water did not lead to significant changes in the composition of the solid samples or of the reaction solution. This can be attributed to a rapid formation of a protective calcium carbonate layer on the surface of the cement paste. The slight decrease of the Ca2+ content in the solution indicates that the growth of this layer occurs within the first few hours. In contrast to the tap water exposure, the results of the experiments with the MgCl2 solutions show features of an intense attack despite the presence of crystalline covering layers. The quick formation of a thick and dense Mg(OH)2 layer does not provide any protection against reactive transport processes. In this experiment, the degradation rate of Ca(OH)2 as well as the Ca2+ release was higher than in all other experiments. In addition the rapid formation of a Mg(OH)2 layer starting already during the first hour of the experiment did not prevent the chloride ingress compared to the other experiments with chloride solutions. The pH value of the reaction solution remains stable and relatively low which indicates a crystallisation process. In the other experiments, performed with demineralized water, alkali chloride solutions, and the CaCl2 solution, no significant formation of potentially protective covering layers and no development of transport inhibiting

  15. Physiological and Chemical Investigations into Microbial Degradation of Synthetic Poly(cis-1,4-isoprene)

    OpenAIRE

    Bode, Helge B; Zeeck, Axel; Plückhahn, Kirsten; Jendrossek, Dieter

    2000-01-01

    Streptomyces coelicolor 1A and Pseudomonas citronellolis were able to degrade synthetic high-molecular-weight poly(cis-1,4-isoprene) and vulcanized natural rubber. Growth on the polymers was poor but significantly greater than that of the nondegrading strain Streptomyces lividans 1326 (control). Measurement of the molecular weight distribution of the polymer before and after degradation showed a time-dependent increase in low-molecular-weight polymer molecules for S. coelicolor 1A and P. citr...

  16. The application of electrochemistry to pharmaceutical stability testing--comparison with in silico prediction and chemical forced degradation approaches.

    Science.gov (United States)

    Torres, Susana; Brown, Roland; Szucs, Roman; Hawkins, Joel M; Zelesky, Todd; Scrivens, Garry; Pettman, Alan; Taylor, Mark R

    2015-11-10

    The aim of this study was to evaluate the use of electrochemistry to generate oxidative degradation products of a model pharmaceutical compound. The compound was oxidized at different potentials using an electrochemical flow-cell fitted with a glassy carbon working electrode, a Pd/H2 reference electrode and a titanium auxiliary electrode. The oxidative products formed were identified and structurally characterized by LC-ESI-MS/MS using a high resolution Q-TOF mass spectrometer. Results from electrochemical oxidation using electrolytes of different pH were compared to those from chemical oxidation and from accelerated stability studies. Additionally, oxidative degradation products predicted using an in silico commercially available software were compared to those obtained from the various experimental methods. The electrochemical approach proved to be useful as an oxidative stress test as all of the final oxidation products observed under accelerated stability studies could be generated; previously reported reactive intermediate species were not observed most likely because the electrochemical mechanism differs from the oxidative pathway followed under accelerated stability conditions. In comparison to chemical degradation tests electrochemical degradation has the advantage of being much faster and does not require the use of strong oxidizing agents. Moreover, it enables the study of different operating parameters in short periods of time and optimisation of the reaction conditions (pH and applied potential) to achieve different oxidative products mixtures. This technique may prove useful as a stress test condition for the generation of oxidative degradation products and may help accelerate structure elucidation and development of stability indicating analytical methods.

  17. Degradation Kinetics of Atorvastatin under Stress Conditions and Chemical Analysis by HPLC

    Directory of Open Access Journals (Sweden)

    Romanélia Spessemille Valotto

    2013-01-01

    Full Text Available Atorvastatin is an antilipemic drug belonging to the statins class, whose reference drug is Pfizer’s Lipitor®. It is used to reduce the levels of lipoproteins rich in cholesterol and reduce the risk of coronary artery disease. It is well-known that calcium atorvastatin (ATV, C66H68CaF2N4O10•3H2O, presents polymorphism. The drug in question is commonly sought after by pharmaceutical industries that produce generic drugs, due to the fact that the drug has a high value price, it is consumed globally, and its patent expired in late 2010. Many questions concerning this drug’s pharmaceutical scope demonstrate its importance regarding stability studies and the identification of degradation products of drugs and pharmaceutical formulations. ATV has been found to degrade under acid and basic conditions, including a first order kinetic degradation under acid conditions, as compared to a zero order kinetic degradation under basic conditions, which tends to be less stable when studied within acid mediums. The rate constant (k for degradation in acid medium was 1.88 × 10−2 s−1 (first order, while for basic medium k = 2.35 × 10−4 mol L−1 s−1 (zero order, demonstrating a lower stability of the drug within acid mediums.

  18. Effects of gamma irradiation on chemical composition and ruminal protein degradation of canola meal

    Energy Technology Data Exchange (ETDEWEB)

    Shawrang, P. [Agriculture, Medical and Industrial Research School, Nuclear Science and Technology Research Institute, Atomic Energy Organization of Iran, P.O. Box 31485-498, Karaj (Iran, Islamic Republic of); Department of Animal Science, Faculty of Agriculture, Tehran University P.O. Box 4111, Karaj (Iran, Islamic Republic of)], E-mail: parvinshawrang@yahoo.co.uk; Nikkhah, A.; Zare-Shahneh, A. [Department of Animal Science, Faculty of Agriculture, Tehran University P.O. Box 4111, Karaj (Iran, Islamic Republic of); Sadeghi, A.A. [Department of Animal Science, Faculty of Agriculture, Science and Research Branch, Islamic Azad University, P.O. Box 14515-4933, Tehran (Iran, Islamic Republic of); Raisali, G. [Radiation Applications Research School, Nuclear Science and Technology Research Institute, Atomic Energy Organization of Iran, P.O. Box 11365-3486, Tehran (Iran, Islamic Republic of); Moradi-Shahrebabak, M. [Department of Animal Science, Faculty of Agriculture, Tehran University P.O. Box 4111, Karaj (Iran, Islamic Republic of)

    2008-07-15

    Gamma irradiation of canola meal (at doses of 25, 50 and 75 kGy) could alter its ruminal protein degradation characteristics by cross-linking of the polypeptide chains. This processing resulted in decrease (linear effect, P<0.001) of ruminal protein degradation and increase (linear effect, P<0.001) of intestinal protein digestibility. The results showed that gamma irradiation at doses higher than 25 kGy can be used as a cross-linking agent to improve protein properties of supplements in ruminant nutrition.

  19. Review of the microbiological, chemical and radiolytic degradation of organic material likely to be present in intermediate level and low level radioactive wastes

    International Nuclear Information System (INIS)

    A review has been made of the microbiological, chemical and radiolytic degradation of the solid organic materials likely to be present in intermediate-level and low-level radioactive wastes. Possible interactions between the three routes for degradation are also discussed. Attention is focussed on the generation of water-soluble degradation products which may form complexes with radioelements. The effects of complexation on radioelement solubility and sorption are considered. Recommendations are made for areas of further research. (author)

  20. Degradation of polycyclic aromatic hydrocarbons by Pseudomonas sp.JM2 isolated from active sewage sludge of chemical plant

    Institute of Scientific and Technical Information of China (English)

    Jing Ma; Li Xu; Lingyun Jia

    2012-01-01

    It is important to screen strains that can decompose polycyclic aromatic hydrocarbons (PAHs) completely and rapidly with good adaptability for bioremediation in a local area.A bacterial strain JM2,which uses phenanthrene as its sole carbon source,was isolated from the active sewage sludge from a chemical plant in Jilin,China and identified as Pseudomonas based on 16S rDNA gene sequence analysis.Although the optimal growth conditions were determined to be pH 6.0 and 37℃,JM2 showed a broad pH and temperature profile.At pH 4.5 and 9.3,JM2 could degrade more than 40% of fluorene and phenanthrene (50 mg/L each) within 4 days.In addition,when the temperature was as low as 4℃,JM2 could degrade up to 24% fluorene and 12% phenanthrene.This showed the potential for JM2 to be applied in bioremediation over winter or in cold regions.Moreover,a nutrient augmentation study showed that adding formate into media could promote PAH degradation,while the supplement of salicylate had an inhibitive effect.Furthermore,in a metabolic pathway study,salicylate,phthaiic acid,and 9-fluorenone were detected during the degradation of fluorene or phenanthrene.In conclusion,Pseudomonas sp.JM2 is a high performance strain in the degradation of fluorene and phenanthrene under extreme pH and temperature conditions.It might be useful in the bioremediation of PAHs.

  1. Mechanism of degradation and elimination of toxic chemicals by microorganism and its application

    International Nuclear Information System (INIS)

    Soluble methanemonooxygenaze (sMMO), a degrading enzyme for aliphatic halogen compounds such as trichloroethylene, was purified from Methylocystics sp. M and the properties were studied. We found that component B of sMMO increased thermal stabilization of hydroxydaze and controlled elimination of iron from the active center. By the cesium condensation model, the cesium incorporation reaction was estimated the first order of 137Cs in the sample solution. 137Cs added in river water could be concentrated by Cs98 strain suspension. The effect of pH on the survival rate of Pseudomonas putida PpY101 in soil was investigated. The survival rate decreased with decreasing pH. Inoculated BHC degradation fungi decreased to death with moving below and it decreased rapidly at low pH (less than pH4.9). (S.Y.)

  2. Triazolines. XXI: Preformulation degradation kinetics and chemical stability of a novel triazoline anticonvulsant.

    Science.gov (United States)

    Freeke Hamelijnck, M A; Stevenson, P J; Kadaba, P K; Damani, L A

    1992-04-01

    The effect of pH, temperature, and two buffer species (citric acid-phosphate and bicarbonate-carbonate) on the stability of 1-(4-chlorophenyl)-5-(4-pyridyl)-delta 2-1,2,3-triazoline (ADD17014; 1), a novel triazoline anticonvulsant, was determined by HPLC. One of the main degradation products of 1 at pH 7.0 was isolated by TLC and identified as the aziridine derivative by MS. Investigations were carried out over a range of pH (2.2-10.7) and buffer concentration [ionic strength (mu), 0.25-4.18] at 23 degrees C. The degradation followed buffer-catalyzed, pseudo-first-order kinetics and was accelerated by a decrease in pH and an increase in temperature. The activation energy for the degradation in citric acid-phosphate buffer (pH 7.0 and constant ionic strength mu at 0.54) was 12.5 kcal/mol. General acid catalysis was observed at pH 7.0 in citric acid-phosphate buffer. The salt effect on the degradation obeyed the modified Debye-Hückel equation well; however, the observed charge product (ZAZB) value (2.69) deviated highly from the theoretical value (1.0), perhaps because of the high mu values (0.25-4.18) of the solutions used. The stability data will be useful in preformulation studies in the development of a stable, oral dosage form of 1. PMID:1501079

  3. Soil chemical properties, organic reserves and root system of a degraded pasture associated introduction of legume

    OpenAIRE

    Carlos Eduardo Santos Fabrice; Cecílio Viega Soares Filho; Marcos Franke Pinto; Silvia Helena Venturoli Perri; Ulysses Cecato; Gustavo Pavan Mateus

    2014-01-01

    The aim was to study the recovery of degraded pasture with the introduction of Stylosanthes macrocephala e capitata cv. Campo Grande on Brachiaria decumbens cv. Basilisk evaluating the levels N-total in roots, biomass, area, and length, diameter and root levels of macro and micronutrients in the soil. The experiment was conducted in the municipality of Andradina, São Paulo State, Brazil. The experimental design was a randomized block design in a split-plot (with and without phosphorus), with ...

  4. Innovative Protocols for in SITU MTBE Degradation by Using Molecular Probes-An Enhanced Chemical-Bio Oxidation Technique

    Energy Technology Data Exchange (ETDEWEB)

    Paul Fallgren

    2009-02-20

    In situ chemical oxidation (ISCO) is a common technology to cleanup petroleum hydrocarbon-contaminated soils and groundwater. Sodium percarbonate (SPC) is an oxidant which is activated by iron (Fe) to produce Fenton-like reactions. Western Research Institute, in conjunction with Regenesis and the U.S. Department of Energy, conducted a study that investigated the performance of a 'safe' oxidant, SPC, to cleanup groundwater and soils contaminated with petroleum hydrocarbons and associated contaminants (e.g., MTBE). Results from a field pilot test in Frenchglen, Oregon showed VOC concentrations in groundwater decreased substantially within 2 weeks after injecting activated SPC (RegenOx). A protocol was established for determining RegenOx TOD in soils and groundwater. Total oxidant demand tests were necessary to determine the correct dosage of RegenOx to apply in the field and sufficiently degrade the contaminants of concern. Bench studies with RegenOx showed this technology was effective in degrading diesel fuel and 1,4-dioxane. The Fe-silica activator (RegenOx Part B) was tested with another oxidant, sodium persulfate. Bench tests results showed the combination of sodium persulfate and RegenOx Part B was effective in reducing PCE, MTBE, benzene, and n-heptane concentrations in water. Overall, the results of this project indicated that most petroleum contaminants in soil and groundwater can be sufficiently degraded using the RegenOx technology.

  5. Prediction of CL-20 chemical degradation pathways, theoretical and experimental evidence for dependence on competing modes of reaction

    Energy Technology Data Exchange (ETDEWEB)

    Qasim, Mohammad M.; Fredrickson, Herbert L.; Honea, P.; Furey, John; Leszczynski, Jerzy; Okovytyy, S.; Szecsody, Jim E.; Kholod, Y.

    2005-10-01

    Highest occupied and lowest unoccupied molecular orbital energies, formation energies, bond lengths and FTIR spectra all suggest competing CL-20 degradation mechanisms. This second of two studies investigates recalcitrant, toxic, aromatic CL-20 intermediates that absorb from 370 to 430 nm. Our earlier study (Struct. Chem., 15, 2004) revealed that these intermediates were formed at high OH- concentrations via the chemically preferred pathway of breaking the C-C bond between the two cyclopentanes, thereby eliminating nitro groups, forming conjugated π bonds, and resulting in a pyrazine three-ring aromatic intermediate. In attempting to find and make dominant a more benign CL-20 transformation pathway, this current research validates hydroxylation results from both studies and examines CL-20 transformations via photo-induced free radical reactions. This article discusses CL-20 competing modes of degradation revealed through: computational calculation; UV/VIS and SF spectroscopy following alkaline hydrolysis; and photochemical irradiation to degrade CL-20 and its byproducts at their respective wavelengths of maximum absorption.

  6. Prediction of CL-20 chemical degradation pathways, theoretical and experimental evidence for dependence on competing modes of reaction.

    Science.gov (United States)

    Qasim, M; Fredrickson, H; Honea, P; Furey, J; Leszczynski, J; Okovytyy, S; Szecsody, J; Kholod, Y

    2005-10-01

    Highest occupied and lowest unoccupied molecular orbital energies, formation energies, bond lengths and FTIR spectra all suggest competing CL-20 degradation mechanisms. This second of two studies investigates recalcitrant, toxic, aromatic CL-20 intermediates that absorb from 370 to 430 nm. Our earlier study (Struct. Chem., 15, 2004) revealed that these intermediates were formed at high OH(-) concentrations via the chemically preferred pathway of breaking the C-C bond between the two cyclopentanes, thereby eliminating nitro groups, forming conjugated pi bonds, and resulting in a pyrazine three-ring aromatic intermediate. In attempting to find and make dominant a more benign CL-20 transformation pathway, this current research validates hydroxylation results from both studies and examines CL-20 transformations via photo-induced free radical reactions. This article discusses CL-20 competing modes of degradation revealed through: computational calculation; UV/VIS and SF spectroscopy following alkaline hydrolysis; and photochemical irradiation to degrade CL-20 and its byproducts at their respective wavelengths of maximum absorption. PMID:16272046

  7. Application of density functional theory (DFT) to study the properties and degradation of natural estrogen hormones with chemical oxidizers

    Energy Technology Data Exchange (ETDEWEB)

    Rokhina, Ekaterina V.; Suri, Rominder P.S., E-mail: rominder.suri@temple.edu

    2012-02-15

    Estrone (E1), 17{beta}-estradiol (E2), estriol (E3), equilin (EQ) and 17{alpha}-estradiol (17{alpha}) estrogen hormones are released by humans and animals and have been detected in the environment and municipal wastewater treatment plants. The structural and electronic properties of natural hormone molecules are investigated by performing density functional theory calculations and used to predict their properties and chemical behavior. Quantitative structure property relationship (QSPR) approach is applied to correlate the estrogenicity associated with the natural estrogen hormones according to their molecular properties. The obtained relationship reveals the importance of the frontier molecular orbital energy in the interpretation of estrogenic activity of hormones, which is consistent with the previous research. Moreover, the obtained molecular descriptors also aid determination of the degradability of hormones, and to rationalize degradation pathways, with chemical oxidizers such as ozone and hydroxyl radical. Both types of interactions belong to the orbital-controlled reactions. The active sites determined by Fukui functions for the estrogen hormone molecules confirm the reaction pattern that initiates the attack of the aromatic ring for both ozone and hydroxyl radical. The reactive sites of the molecules are mapped with subsequent reaction intermediates and compared with experimental data obtained from the literature. - Highlights: Black-Right-Pointing-Pointer DFT methods described in this paper are suitable for predicting the degradation behavior of natural estrogen hormones. Black-Right-Pointing-Pointer Using QSAR, the estrogenicity of natural hormones was determined by DFT descriptors. Black-Right-Pointing-Pointer The sites of primary ozone and hydroxyl radical attack were predicted using DFT, and findings confirmed by experimental data.

  8. Chemical durability and degradation mechanisms of HT9 based alloy waste forms with variable Zr content

    Energy Technology Data Exchange (ETDEWEB)

    Olson, L. N. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-10-30

    In Corrosion studies were undertaken on alloy waste forms that can result from advanced electrometallurgical processing techniques to better classify their durability and degradation mechanisms. The waste forms were based on the RAW3-(URe) composition, consisting primarily of HT9 steel and other elemental additions to simulate nuclear fuel reprocessing byproducts. The solution conditions of the corrosion studies were taken from an electrochemical testing protocol, and meant to simulate conditions in a repository. The alloys durability was examined in alkaline and acidic brines.

  9. Wet oxidative degradation of cellulosic wastes 5- chemical and thermal properties of the final waste forms

    International Nuclear Information System (INIS)

    In this study, the residual solution arising from the wet oxidative degradation of solid organic cellulosic materials, as one of the component of radioactive solid wastes, using hydrogen peroxide as oxidant. Were incorporated into ordinary Portland cement matrix. Leaching as well as thermal characterizations of the final solidified waste forms were evaluated to meet the final disposal requirements. Factors, such as the amount of the residual solution incorporated, types of leachant. Release of different radionuclides and freezing-thaw treatment, that may affect the leaching characterization. Were studied systematically from the data obtained, it was found that the final solid waste from containing 35% residual solution in tap water is higher than that in ground water or sea water. Based on the data obtained from thermal analysis, it could be concluded that incorporating the residual solution form the wet oxidative degradation of cellulosic materials has no negative effect on the hydration of cement materials and consequently on the thermal stability of the final solid waste from during the disposal process

  10. Microwave-assisted chemical oxidation of biological waste sludge: simultaneous micropollutant degradation and sludge solubilization.

    Science.gov (United States)

    Bilgin Oncu, Nalan; Akmehmet Balcioglu, Isil

    2013-10-01

    Microwave-assisted hydrogen peroxide (MW/H2O2) treatment and microwave-assisted persulfate (MW/S2O8(2-)) treatment of biological waste sludge were compared in terms of simultaneous antibiotic degradation and sludge solubilization. A 2(3) full factorial design was utilized to evaluate the influences of temperature, oxidant dose, and holding time on the efficiency of these processes. Although both MW/H2O2 and MW/S2O8(2-) yielded ≥97% antibiotic degradation with 1.2g H2O2 and 0.87 g S2O8(2-) per gram total solids, respectively, at 160 °C in 15 min, MW/S2O8(2-) was found to be more promising for efficient sludge treatment at a lower temperature and a lower oxidant dosage, as it allows more effective activation of persulfate to produce the SO4(-) radical. Relative to MW/H2O2, MW/S2O8(2-) gives 48% more overall metal solubilization, twofold higher improvement in dewaterability, and the oxidation of solubilized ammonia to nitrate in a shorter treatment period. PMID:23928124

  11. Microstructure, mechanical properties and chemical degradation of brazed AISI 316 stainless steel/alumina systems

    Energy Technology Data Exchange (ETDEWEB)

    Paiva, O.C. [Instituto Superior de Engenharia do Porto (ISEP), Rua Dr. Antonio Bernardino de Almeida 431, 4200-072 Porto (Portugal)], E-mail: omp@isep.ipp.pt; Barbosa, M.A. [Instituto de Engenharia Biomedica (INEB), Rua do Campo Alegre, 823, 4150-180 Porto (Portugal); Faculdade de Engenharia da Universidade do Porto (FEUP), Rua Roberto Frias s/n, 4200-465 Porto (Portugal)

    2008-05-15

    The main aims of the present study are simultaneously to relate the brazing parameters with: (i) the correspondent interfacial microstructure, (ii) the resultant mechanical properties and (iii) the electrochemical degradation behaviour of AISI 316 stainless steel/alumina brazed joints. Filler metals on such as Ag-26.5Cu-3Ti and Ag-34.5Cu-1.5Ti were used to produce the joints. Three different brazing temperatures (850, 900 and 950 deg. C), keeping a constant holding time of 20 min, were tested. The objective was to understand the influence of the brazing temperature on the final microstructure and properties of the joints. The mechanical properties of the metal/ceramic (M/C) joints were assessed from bond strength tests carried out using a shear solicitation loading scheme. The fracture surfaces were studied both morphologically and structurally using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction analysis (XRD). The degradation behaviour of the M/C joints was assessed by means of electrochemical techniques. It was found that using a Ag-26.5Cu-3Ti brazing alloy and a brazing temperature of 850 deg. C, produces the best results in terms of bond strength, 234 {+-} 18 MPa. The mechanical properties obtained could be explained on the basis of the different compounds identified on the fracture surfaces by XRD. On the other hand, the use of the Ag-34.5Cu-1.5Ti brazing alloy and a brazing temperature of 850 deg. C produces the best results in terms of corrosion rates (lower corrosion current density), 0.76 {+-} 0.21 {mu}A cm{sup -2}. Nevertheless, the joints produced at 850 deg. C using a Ag-26.5Cu-3Ti brazing alloy present the best compromise between mechanical properties and degradation behaviour, 234 {+-} 18 MPa and 1.26 {+-} 0.58 {mu}A cm{sup -2}, respectively. The role of Ti diffusion is fundamental in terms of the final value achieved for the M/C bond strength. On the contrary, the Ag and Cu distribution along the

  12. Durability of concrete: characterization and modeling of physical and chemical degradation of cement

    International Nuclear Information System (INIS)

    Within the frame of nuclear waste management, and more particularly waste storage by confinement in parcels, concrete and geological environment, this research aims at predicting the durability of a concrete paste and of all concrete works. This prediction is based on a material characterization (determination of the thickness and composition of the attacked area) whatever the degradation duration is. The adopted approach is to model concrete lixiviation and to compare model results with experimental results. The model is also used to assess the influence of a great number of parameters, and to simulate non experimented cases. Thus, the author reports a bibliographical study on cement, and presents the equations of a lixiviation model. He reports experiments aimed at verifying modelling hypotheses and at acquiring necessary data. The model is then numerically solved, and applied to an experimental case. Experimental results are compared with modelling results, and a prediction is performed for a 300 year-duration

  13. Chemical composition and the nutritive value of pistachio epicarp (in situ degradation and in vitro gas production techniques

    Directory of Open Access Journals (Sweden)

    Somayeh Bakhshizadeh

    2014-04-01

    Full Text Available The nutritive value of pistachio epicarp (PE was evaluated by in situ and in vitro techniques. Chemical analysis indicated that PE was high in crude protein (11.30% and low in neutral detergent fiber (26.20%. Total phenols, total tannins, condensed tannins and hydrolysable tannins contents in PE were 8.29%, 4.48%, 0.49% and 3.79%, respectively. Ruminal dry matter and crude protein degradation after 48 hr incubation were 75.21% and 82.52%, respectively. The gas production volume at 48 hr for PE was 122.47 mL g-1DM. As a whole, adding polyethylene glycol (PEG to PE increased (p < 0.05 gas production volumes, organic matter digestibility and the metabolizable energy that illustrated inhibitory effect of phenolics on rumen microbial fermentation and the positive influence of PEG on digestion PE. The results showed that PE possessed potentials to being used as feed supplements.

  14. Rapid, Efficient and Versatile Strategies for Functionally Sophisticated Polymers and Nanoparticles: Degradable Polyphosphoesters and Anisotropic Distribution of Chemical Functionalities

    Science.gov (United States)

    Zhang, Shiyi

    The overall emphasis of this dissertation research included two kinds of asymmetrically-functionalized nanoparticles with anisotropic distributions of chemical functionalities, three degradable polymers synthesized by organocatalyzed ring-opening polymerizations, and two polyphosphoester-based nanoparticle systems for various biomedical applications. Inspired by the many hierarchical assembly processes that afford complex materials in Nature, the construction of asymmetrically-functionalized nanoparticles with efficient surface chemistries and the directional organization of those building blocks into complex structures have attracted much attention. The first method generated a Janus-faced polymer nanoparticle that presented two orthogonally click-reactive surface chemistries, thiol and azido. This robust method involved reactive functional group transfer by templating against gold nanoparticle substrates. The second method produced nanoparticles with sandwich-like distribution of crown ether functionalities through a stepwise self-assembly process that utilized crown ether-ammonium supramolecular interactions to mediate inter-particle association and the local intra-particle phase separation of unlike hydrophobic polymers. With the goal to improve the efficiency of the production of degradable polymers with tunable chemical and physical properties, a new type of reactive polyphosphoester was synthesized bearing alkynyl groups by an organocatalyzed ring-opening polymerization, the chemical availability of the alkyne groups was investigated by employing "click" type azide-alkyne Huisgen cycloaddition and thiol-yne radical-mediated reactions. Based on this alkyne-functionalized polyphosphoester polymer and its two available "click" type reactions, two degradable nanoparticle systems were developed. To develop the first system, the well defined poly(ethylene oxide)-block-polyphosphester diblock copolymer was transformed into a multifunctional Paclitaxel drug

  15. Inducing an Order-Order Morphological Transition via Chemical Degradation of Amphiphilic Diblock Copolymer Nano-Objects.

    Science.gov (United States)

    Ratcliffe, Liam P D; Couchon, Claudie; Armes, Steven P; Paulusse, Jos M J

    2016-06-13

    The disulfide-based cyclic monomer, 3-methylidene-1,9-dioxa-5,12,13-trithiacyclopentadecane-2,8-dione (MTC), is statistically copolymerized with 2-hydroxypropyl methacrylate to form a range of diblock copolymer nano-objects via reversible addition-fragmentation chain transfer (RAFT) polymerization. Poly(glycerol monomethacrylate) (PGMA) is employed as the hydrophilic stabilizer block in this aqueous polymerization-induced self-assembly (PISA) formulation, which affords pure spheres, worms or vesicles depending on the target degree of polymerization for the core-forming block. When relatively low levels (99%) are achieved and high blocking efficiencies are observed, as judged by (1)H NMR spectroscopy and gel permeation chromatography (GPC), respectively. However, the side reactions that are known to occur when cyclic allylic sulfides such as MTC are statistically copolymerized with methacrylic comonomers lead to relatively broad molecular weight distributions. Nevertheless, the worm-like nanoparticles obtained via PISA can be successfully transformed into spherical nanoparticles by addition of excess tris(2-carboxyethyl)phosphine (TCEP) at pH 8-9. Surprisingly, DLS and TEM studies indicate that the time scale needed for this order-order transition is significantly longer than that required for cleavage of the disulfide bonds located in the worm cores indicated by GPC analysis. This reductive degradation pathway may enable the use of these chemically degradable nanoparticles in biomedical applications, such as drug delivery systems and responsive biomaterials. PMID:27228898

  16. Inducing an Order–Order Morphological Transition via Chemical Degradation of Amphiphilic Diblock Copolymer Nano-Objects

    Science.gov (United States)

    2016-01-01

    The disulfide-based cyclic monomer, 3-methylidene-1,9-dioxa-5,12,13-trithiacyclopentadecane-2,8-dione (MTC), is statistically copolymerized with 2-hydroxypropyl methacrylate to form a range of diblock copolymer nano-objects via reversible addition–fragmentation chain transfer (RAFT) polymerization. Poly(glycerol monomethacrylate) (PGMA) is employed as the hydrophilic stabilizer block in this aqueous polymerization-induced self-assembly (PISA) formulation, which affords pure spheres, worms or vesicles depending on the target degree of polymerization for the core-forming block. When relatively low levels (99%) are achieved and high blocking efficiencies are observed, as judged by 1H NMR spectroscopy and gel permeation chromatography (GPC), respectively. However, the side reactions that are known to occur when cyclic allylic sulfides such as MTC are statistically copolymerized with methacrylic comonomers lead to relatively broad molecular weight distributions. Nevertheless, the worm-like nanoparticles obtained via PISA can be successfully transformed into spherical nanoparticles by addition of excess tris(2-carboxyethyl)phosphine (TCEP) at pH 8–9. Surprisingly, DLS and TEM studies indicate that the time scale needed for this order–order transition is significantly longer than that required for cleavage of the disulfide bonds located in the worm cores indicated by GPC analysis. This reductive degradation pathway may enable the use of these chemically degradable nanoparticles in biomedical applications, such as drug delivery systems and responsive biomaterials. PMID:27228898

  17. Chemical Composition of Seed Oil from Roselle (Hibiscus sabdariffa L. and the Kinetics of Degradation of the Oil During Heating

    Directory of Open Access Journals (Sweden)

    G. Bouanga-Kalou

    2011-02-01

    Full Text Available The aim of the study was to investigate the chemical composition and the kinetics of degradation of roselle seed oil during heating. The seed is a good source of oil (23.27%. The physical properties of the oil extracts showed the state to be liquid at room temperature and indicated that the oil had refractive index, 1.4652; the peroxide value, 3.15 (meq O2/kg oil; free fatty acid, 0.82%; iodine value, 97.78%; saponification value, 198.45 and viscosity, 15.15 (mPa.s at 25ºC. Gas liquid chromatography technique has been developed for identification and quantitative determination of total unsaturated and saturated fatty acids shows that the crude oil had 73.4 and 26.57%, respectively. DSC indicates the presence of two components in oil extracted. The first peak at low melting point appears at -20.53°C (Hf = +3.00 J/g and the second peak appears to -2.17°C (Hf = +0.49 J/g. The degradation kinetic of the oil was also investigated. The thermal oxidation of the double bonds of the oil showed a first-order thermal oxidation kinetic and the Arrhenius plot yielded a straight line with a slope equivalent to activation energy of 9.041 KJ/mol. There is the possibility of considering the seed as feed supplement and its oil for industrial application.

  18. Inhibition of catecholamine degradation ameliorates while chemical sympathectomy aggravates the severity of acute Friend retrovirus infection in mice.

    Science.gov (United States)

    Bloemker, Dominique; Mollerus, Sina; Gibbert, Kathrin; Dittmer, Ulf; del Rey, Adriana; Schedlowski, Manfred; Engler, Harald

    2016-05-01

    Several lines of evidence indicate that the sympathetic nervous system (SNS) might be involved in the pathogenesis and progression of retroviral infections. However, experimental data are scarce and findings inconsistent. Here, we investigated the role of the SNS during acute infection with Friend virus (FV), a pathogenic murine retrovirus that causes polyclonal proliferation of erythroid precursor cells and splenomegaly in adult mice. Experimental animals were infected with FV complex, and viral load, spleen weight, and splenic noradrenaline (NA) concentration was analyzed until 25 days post infection. Results show that FV infection caused a massive but transient depletion in splenic NA during the acute phase of the disease. At the peak of the virus-induced splenomegaly, splenic NA concentration was reduced by about 90% compared to naïve uninfected mice. Concurrently, expression of the catecholamine degrading enzymes monoamine oxidase A (MAO-A) and catechol-O-methyltransferase (COMT) was significantly upregulated in immune cells of the spleen. Pharmacological inhibition of MAO-A and COMT by the selective inhibitors clorgyline and 3,5-dinitrocatechol, respectively, efficiently blocked NA degradation and significantly reduced viral load and virus-induced splenomegaly. In contrast, chemical sympathectomy prior to FV inoculation aggravated the acute infection and extended the duration of the disease. Together these findings demonstrate that catecholamine availability at the site of viral replication is an important factor affecting the course of retroviral infections. PMID:26880342

  19. Degradation of the endocrine disrupting chemicals (EDCs) carbamazepine, clofibric acid, and iopromide by corona discharge over water.

    Science.gov (United States)

    Krause, Holger; Schweiger, Bianca; Schuhmacher, Jörg; Scholl, Saskia; Steinfeld, Ute

    2009-04-01

    Common wastewater treatment plants often do not eliminate endocrine disrupting chemicals (EDCs). Aqueous solutions of three EDCs were treated with an enhanced corona discharge technology. The three EDCs were clofibric acid, a blood lipid regulator, carbamazepine, an antiepileptic drug, and iopromide, a contrast media. To simulate real conditions, EDC solutions containing landfill leachate were also used. In our setup, two barrier electrodes provided an atmospheric pressure corona discharge over a thin water film, in which the counter-electrode was submerged. Clofibric acid, carbamazepine, and iopromide were effectively removed from a single solution. After a treatment of 15min, there were no traces of iopromide estrogen activity either as a single substance or as degradation products when using an E-Screen Assay. Continuous treatment was compared with pulsed treatment using carbamazepine solutions mixed with pretreated landfill leachate. Best degradation results were achieved with a 500 W continuous duty cycle treatment. Counter-electrodes from materials such as boron doped diamond (BDD), titanium iridium oxide, and iron were investigated for their influences on the process effectivity. Significant improvements were achieved by using an enclosed reactor, BDD electrodes, and circulating only a fresh air or argon/air mixture as cooling gas through the barrier electrodes. PMID:19150730

  20. Characterisation of the non-asphaltene products of mild chemical degradation of asphaltenes

    Energy Technology Data Exchange (ETDEWEB)

    Ekweozor, C.M.

    1986-01-01

    The major steranes of the non-asphaltene fraction of Nigerian tar sand bitumen (maltene) are the C{sub 27-29} and C{sub 28-29} regular steranes. The reducing-metal reaction products of the corresponding asphaltenes (maltene-I) contain mainly C{sub 27-29} regular steranes with the 14{beta}(H),17{beta}(H);20R+S and 14{alpha}(H),17{alpha}(H);20R+S configurations as well as the corresponding diasteranes having the 13{beta}(H),17{alpha}(H);20R+S configuration. These sterane distributions suggest that maltene-I corresponds to an unaltered oil while the maltene is equivalent to the product of severe biodegradation of maltene-I. This is consistent with maltene-I being the remnant of original oil trapped within the asphaltene matrix and protected from the effect of in-reservoir biodegradation. Degradation of Nigerian asphaltenes by refluxing with ferric chloride-acetic anhydride or methanolic potassium hydroxide also releases soluble reaction products having the characteristics of unaltered oil such as the presence of n-alkanes having an unbiased distribution. These methods appear to be milder and more suitable than reducing-metal reactions for releasing hydrocarbons occluded by asphaltenes. 15 refs., 3 figs., 2 tabs.

  1. Characterization of the non-asphaltene products of mild chemical degradation of asphaltenes

    Energy Technology Data Exchange (ETDEWEB)

    Ekweozor, C.M.

    1986-01-01

    The major steranes of the non-asphaltene fraction of Nigerian tar sand bitumen (maltene) are the C/sub 27/-C/sub 29/ diasteranes (13..beta.. (H),17..cap alpha.. (H); 20 R + S) and C/sub 28/-C/sub 29/ regular steranes (14..beta.. (H),17..beta.. (H); 20S). The reducing metal reaction products of the corresponding asphaltenes (maltene-I) contain mainly C/sub 27/-C/sub 29/ regular steranes with the 14..beta.. (H),17..beta.. (H); 20R + S and 14..cap alpha.. (H),17..cap alpha.. (H); 20R + S configurations as well as the corresponding diasteranes having the 13..beta.. (H),17..cap alpha.. (H); 20R + S configuration. These sterane distributions suggest that maltene-I corresponds to an unaltered oil whilst the maltene is equivalent to the product of severe biodegradation of maltene-I. This is consistent with maltene-I being the remnant of original oil trapped within the asphaltene matrix and protected from the effect of in-reservoir biodegradation. Degradation of Nigerian asphaltenes by refluxing with ferric chloride-acetic anhydride or methanolic potassium hydroxide also releases soluble reaction products having the characteristics of unaltered oil such as the presence of n-alkanes having an unbiased distribution. These methods appear to be milder and more suitable than reducing metal reactions for releasing hydrocarbons occluded by asphaltenes.

  2. Chemical and physiological relevance of glucose degradation products in peritoneal dialysis.

    Science.gov (United States)

    Mittelmaier, Stefan; Niwa, Toshimitsu; Pischetsrieder, Monika

    2012-01-01

    Fibrosis and vascular sclerosis are main complications that limit the long-term application of peritoneal dialysis (PD). Low biocompatibility has been largely attributed to the presence of glucose degradation products (GDPs), which are formed during the heat sterilization of PD fluids. GDPs readily modify proteins in the peritoneum, leading to a decline of their biological function. After absorption, GDPs can also promote systemic protein glycation. Additionally, GDPs may augment DNA glycation, a process enhanced in uremia. Apart from their glycating activity, GDPs induce cytotoxicity and interfere with cell signaling in peritoneal mesothelial cells. Targeted screening revealed the nature of the 6 major GDPs with α-dicarbonyl structure as 3-deoxyglucosone, 3-deoxygalactosone, glucosone, glyoxal, methylglyoxal, and 3,4-dideoxyglucosone-3-ene. Valid quantification of these GDPs was achieved by ultrahigh-performance liquid chromatography/diode array detector/tandem mass spectrometry. Identification and quantification of single GDPs allow a structure-dependent risk evaluation. As a consequence, PD fluids and processes can be improved to reduce the GDP burden of patients undergoing PD.

  3. Effect of chemical degradation followed by toothbrushing on the surface roughness of restorative composites

    Directory of Open Access Journals (Sweden)

    Fernanda Regina Voltarelli

    2010-12-01

    Full Text Available OBJECTIVES: The aim of the present study was to assess the effect of the exposure to food-simulating liquids prior to brushing simulation on the surface roughness of five composite materials (Quixfil, Filtek Supreme, Esthet-X, Filtek Z250, Tetric Ceram. Material and METHODS: Twenty cylinders (5 mm diameter and 4 mm height of each composite were randomly allocated to 4 groups (n=5, according to the food-simulating liquid in which they were immersed for 7 days at 37°C: artificial saliva, heptane, citric acid, and ethanol. After this period, the top surface of composite cylinders was submitted to 7,500 brushing cycles (200 g load. Measurements of the surface roughness (Ra, ¼m were carried out before and after the exposure to the chemicals/brushing simulation. Changes on the morphology of composite surfaces were observed through scanning electron microscopy (SEM. RESULTS: The statistical analysis (ANOVA with cofactor / Tukey's test, α=5% detected a significant interaction between solutions and composite resins. Esthet-X, Filtek Z250 and Tetric Ceram were not affected by the food-simulating liquids/toothbrushing. Citric acid and ethanol increased the surface roughness of Quixfil and Filtek Supreme, respectively. SEM images corroborate the surface roughness findings, demonstrating the negative effect from chemical solutions and mechanical abrasion. CONCLUSIONS: The surface roughness of composite resin materials are differently affected by the food-simulating solutions, depending on the immersion media.

  4. Genetic and chemical characterization of ibuprofen degradation by Sphingomonas Ibu-2.

    Science.gov (United States)

    Murdoch, Robert W; Hay, Anthony G

    2013-03-01

    Sphingomonas Ibu-2 has the unusual ability to cleave the acid side chain from the pharmaceutical ibuprofen and related arylacetic acid derivatives to yield corresponding catechols under aerobic conditions via a previously uncharacterized mechanism. Screening a chromosomal library of Ibu-2 DNA in Escherichia coli EPI300 allowed us to identify one fosmid clone (pFOS3G7) that conferred the ability to metabolize ibuprofen to isobutylcatechol. Characterization of pFOS3G7 loss-of-function transposon mutants permitted identification of five ORFs, ipfABDEF, whose predicted amino acid sequences bore similarity to the large and small units of an aromatic dioxygenase (ipfAB), a sterol carrier protein X (SCPx) thiolase (ipfD), a domain of unknown function 35 (DUF35) protein (ipfE) and an aromatic CoA ligase (ipfF). Two additional ORFs, ipfH and ipfI, which encode putative ferredoxin reductase and ferredoxin components of an aromatic dioxygenase system, respectively, were also identified on pFOS3G7. Complementation of a markerless loss-of-function ipfD deletion mutant restored catechol production as did complementation of the ipfF Tn mutant. Expression of subcloned ipfABDEF alone in E. coli did not impart full metabolic activity unless coexpressed with ipfHI. CoA ligation followed by ring oxidation is common to phenylacetic acid pathways. However, the need for a putative SCPx thiolase (IpfD) and DUF35 protein (IpfE) in aerobic arylacetic acid degradation is unprecedented. This work provides preliminary insights into the mechanism behind this novel arylacetic acid-deacylating, catechol-generating activity.

  5. Degradation Of Environmental Barrier Coatings (EBC) Due To Chemical and Thermal Expansion Incompatibility

    Science.gov (United States)

    Lee, Kang N.; King, Deboran (Technical Monitor)

    2001-01-01

    Current environmental barrier coatings (EBCs) consist of multiple layers, with each layer having unique properties to meet the various requirements for successful EBCs. As a result, chemical and thermal expansion compatibility between layers becomes an important issue to maintaining durability. Key constituents in current EBCs are mullite (3Al2O3-2SiO2), BSAS (BaO(1-x)-SrO(x)-Al2O3-2SiO2), and YSZ (ZrO2-8 wt.% Y2O3). The mullite-BSAS combination appears benign although significant diffusion occurs. Mullite-YSZ and BSAS-YSZ combinations do not react up to 1500 C. Thermally grown SiO2- BSAS and mullite-BSAS-YSZ combinations are most detrimental, forming low melting glasses. Thermal expansion mismatch between YSZ and mullite or BSAS causes severe cracking and delamination.

  6. Advanced Chemical Reduction of Reduced Graphene Oxide and Its Photocatalytic Activity in Degrading Reactive Black 5

    Directory of Open Access Journals (Sweden)

    Christelle Pau Ping Wong

    2015-10-01

    Full Text Available Textile industries consume large volumes of water for dye processing, leading to undesirable toxic dyes in water bodies. Dyestuffs are harmful to human health and aquatic life, and such illnesses as cholera, dysentery, hepatitis A, and hinder the photosynthetic activity of aquatic plants. To overcome this environmental problem, the advanced oxidation process is a promising technique to mineralize a wide range of dyes in water systems. In this work, reduced graphene oxide (rGO was prepared via an advanced chemical reduction route, and its photocatalytic activity was tested by photodegrading Reactive Black 5 (RB5 dye in aqueous solution. rGO was synthesized by dispersing the graphite oxide into the water to form a graphene oxide (GO solution followed by the addition of hydrazine. Graphite oxide was prepared using a modified Hummers’ method by using potassium permanganate and concentrated sulphuric acid. The resulted rGO nanoparticles were characterized using ultraviolet-visible spectrophotometry (UV-Vis, X-ray powder diffraction (XRD, Raman, and Scanning Electron Microscopy (SEM to further investigate their chemical properties. A characteristic peak of rGO-48 h (275 cm−1 was observed in the UV spectrum. Further, the appearance of a broad peak (002, centred at 2θ = 24.1°, in XRD showing that graphene oxide was reduced to rGO. Based on our results, it was found that the resulted rGO-48 h nanoparticles achieved 49% photodecolorization of RB5 under UV irradiation at pH 3 in 60 min. This was attributed to the high and efficient electron transport behaviors of rGO between aromatic regions of rGO and RB5 molecules.

  7. Degradative crystal–chemical transformations of clay minerals under the influence of cyanobacterium-actinomycetal symbiotic associations

    Directory of Open Access Journals (Sweden)

    Ekaterina Ivanova

    2014-04-01

    Full Text Available Cyanobacteria and actinomycetes are essential components of soil microbial community and play an active role in ash elements leaching from minerals of the parent rock. Content and composition of clay minerals in soil determine the sorption properties of the soil horizons, water-holding capacity of the soil, stickiness, plasticity, etc. The transformative effect of cyanobacterial–actinomycetes associations on the structure of clay minerals – kaolinite, vermiculite, montmorillonite, biotite and muscovite – was observed, with the greatest structural lattice transformation revealed under the influence of association in comparison with monocultures of cyanobacterium and actinomycete. The range of the transformative effect depended both on the type of biota (component composition of association and on the crystal–chemical parameters of the mineral itself (trioctahedral mica – biotite, was more prone to microbial degradation than the dioctahedral – muscovite. The formation of the swelling phase – the product of biotite transformation into the mica–vermicullite mixed-layered formation was revealed as a result of association cultivation. Crystal chemical transformation of vermiculite was accompanied by the removal of potassium (К, magnesium (Mg and aluminum (Al from the crystal lattice. The study of such prokaryotic communities existed even in the early stages of the Earth's history helps to understand the causes and nature of the transformations undergone by the atmosphere, hydrosphere and lithosphere of the planet.contribution of treatments on structure induces and model parameters are discussed in the paper.

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

    International Nuclear Information System (INIS)

    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 Cu2+ and Ni2+ 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 Eu3+ 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

  9. Chemical Composition of Seed Oil from Roselle (Hibiscus sabdariffa L. and the Kinetics of Degradation of the Oil During Heating

    Directory of Open Access Journals (Sweden)

    G. Bouanga-Kalou

    2011-03-01

    Full Text Available The aim of the study was to investigate the chemical composition and the kinetics of degradation of roselle seed oil during heating. The seed is a good source of oil (23.27%. The physical properties of the oil extracts showed the state to be liquid at room temperature and indicated that the oil had refractive index, 1.4652; the peroxide value, 3.15 (meq O2/kg oil; free fatty acid, 0.82%; iodine value, 97.78%; saponification value, 198.45 and viscosity, 15.15 (mPa.s at 25ºC. Gas liquid chromatography technique has been developed for identification and quantitative determination of total unsaturated and saturated fatty acids shows that the crude oil had 73.4 and 26.57%, respectively. DSC indicates the presence of two components in oil extracted. The first peak at low melting point appears at -20.53°C ΔHf = +3.00 J/g and the second peak appears to - 2.17ºC ΔHf = +0.49 J/g. The degradation kinetic of the oil was also investigated. The thermal oxidation of the double bonds of the oil showed a first-order thermal oxidation kinetic and the Arrhenius plot yielded a straight line with a slope equivalent to activation energy of 9.041 KJ/mol.There is the possibility of considering the seed as feed supplement and its oil for industrial application.

  10. 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.

  11. Effects of species and season on chemical composition and ruminal crude protein and organic matter degradability of some multi-purpose tree species by West African dwarf rams.

    Science.gov (United States)

    Arigbede, O M; Anele, U Y; Südekum, K-H; Hummel, J; Oni, A O; Olanite, J A; Isah, A O

    2012-04-01

    Seasonal chemical composition and ruminal organic matter (OM) and crude protein (CP) degradabilities were determined in four tropical multi-purpose tree species (MPTS) namely; Pterocarpus santalinoides, Grewia pubescens, Enterolobium cyclocarpum and Leucaena leucocephala. Three West African dwarf (WAD) rams fitted with permanent rumen cannula were used for the degradability trials. Foliage samples were collected four times to represent seasonal variations as follows: January--mid dry; April--late dry; July--mid rainy and October--late rainy seasons. Leaf samples were randomly collected from the trees for estimation of dry matter (DM) and chemical composition. Ruminal in sacco OM and CP degradabilities were estimated from residues in nylon bags. All samples had high CP (161-259 g/kg DM) and moderate fibre concentrations [neutral detergent fibre (without residual ash], 300-501 g/kg DM; acid detergent fibre (without residual ash), 225-409 g/kg DM and acid detergent lignin, 87-179 g/kg DM across seasons. Interaction effects of species and season on chemical composition were highly significant (p = 0.001) except for trypsin inhibitor (p = 0.614). The MPTS recorded more than 60% OM and CP degradability at 24 h, which implied that they were all highly degradable in the rumen. Their incorporation into ruminant feeding systems as dry season forage supplements is therefore recommended.

  12. Hydrological character of the soil of a degraded area: comparison of analysis physical, chemical and floristic vegetational

    Science.gov (United States)

    Manfredi, Paolo; Cassinari, Chiara; Giupponi, Luca; Sichel, Giorgio Maria; Trevisan, Marco

    2013-04-01

    This work is an integral part of a project co-financed by the European Union "Environmental recovery of degraded soils and desertified land by a new technology treatment for the recovery of the land" (Life 10 ENV IT 400 "New Life"); this technology is based on a treatment (patented by m.c.m. Ecosistemi) of chemical mechanical processing of degraded soils with an initial process of disgregation of the same followed by their reconstitution incorporating soil matrices, a subsequent polycondensation with humic acids and a final restoration. The area of intervention of the New Life project lies in the municipal territory of Piacenza, where between the years 70 and 80 has been made a landfill for municipal solid waste with subsequent restoration work by placing a layer of soil cover. The first phase of the New Life project was that of a physical and chemical characterization of different cover soils of the area combined with floristic-vegetational analysis. At this stage the present study aims to compare the data related to the analysis of the vegetation with those returned by investigation of hydrological characteristics of soils performed by laboratory methods, together to confront two theoretical calculation methods for determination of hydrological parameters. The comparison of the ecological study of the vegetation with the outcomes obtained by the classical methods regarding the determination of water retention, allows you to have a picture that is as detailed as possible in describing the characteristics of the substrate. The comparison also with the two methods of calculation, which determines the hydrological character conditions in average soil condition, allows you to ascertain the actual disturbance of the soil in the area. In order to delineate the hydrological characteristics of the soils sampled, were quantified by the Maximum Water Concentration, the capacity range, the point of Withering by the method of the Tensiometric box and the Pressure Membrane

  13. Combined use of GIS and environmental indicators for assessment of chemical, physical and biological soil degradation in a Spanish Mediterranean region.

    Science.gov (United States)

    de Paz, José-Miguel; Sánchez, Juan; Visconti, Fernando

    2006-04-01

    Soil is one of the main non-renewable natural resources in the world. In the Valencian Community (Mediterranean coast of Spain), it is especially important because agriculture and forest biomass exploitation are two of the main economic activities in the region. More than 44% of the total area is under agriculture and 52% is forested. The frequently arid or semi-arid climate with rainfall concentrated in few events, usually in the autumn and spring, scarcity of vegetation cover, and eroded and shallow soils in several areas lead to soil degradation processes. These processes, mainly water erosion and salinization, can be intense in many locations within the Valencian Community. Evaluation of soil degradation on a regional scale is important because degradation is incompatible with sustainable development. Policy makers involved in land use planning require tools to evaluate soil degradation so they can go on to develop measures aimed at protecting and conserving soils. In this study, a methodology to evaluate physical, chemical and biological soil degradation in a GIS-based approach was developed for the Valencian Community on a 1/200,000 scale. The information used in this study was obtained from two different sources: (i) a soil survey with more than 850 soil profiles sampled within the Valencian Community, and (ii) the environmental information implemented in the Geo-scientific map of the Valencian Community digitised on an Arc/Info GIS. Maps of physical, chemical and biological soil degradation in the Valencian Community on a 1/200,000 scale were obtained using the methodology devised. These maps can be used to make a cost-effective evaluation of soil degradation on a regional scale. Around 29% of the area corresponding to the Valencian Community is affected by high to very high physical soil degradation, 36% by high to very high biological degradation, and 6% by high to very high chemical degradation. It is, therefore, necessary to draw up legislation and to

  14. Chemical composition, rumen degradability, protein utilization and lactation response to selected tree leaves as substitute of cottonseed cake in the diet of dairy goats

    NARCIS (Netherlands)

    Khan, N.A.; Habib, G.; Ullah, G.

    2009-01-01

    The aim of this study was to investigate the potential of leaves from Grewia oppositifolia (G. oppositifolia) and Ziziphus mauritiana (Z. mauritiana) as a crude protein (CP) supplements to low quality diets of goats in Pakistan. Chemical composition and CP degradability of the tree leaves were compa

  15. Physical and chemical degradation behavior of sputtered aluminum doped zinc oxide layers for Cu(In,Ga)Se2 solar cells

    NARCIS (Netherlands)

    Theelen, M.; Boumans, T.; Stegeman, F.; Colberts, F.; Illiberi, A.; Berkum, J. van; Barreau, N.; Vroon, Z.; Zeman, M.

    2014-01-01

    Sputtered aluminum doped zinc oxide (ZnO:Al) layers on borosilicate glass were exposed to damp heat (85 C/85% relative humidity) for 2876 h to accelerate the physical and chemical degradation behavior. The ZnO:Al samples were characterized by electrical, compositional and optical measurements before

  16. Degradation of di(2-ethyl hexyl) phthalate by Fusarium culmorum: Kinetics, enzymatic activities and biodegradation pathway based on quantum chemical modelingpathway based on quantum chemical modeling.

    Science.gov (United States)

    Ahuactzin-Pérez, Miriam; Tlecuitl-Beristain, Saúl; García-Dávila, Jorge; González-Pérez, Manuel; Gutiérrez-Ruíz, María Concepción; Sánchez, Carmen

    2016-10-01

    Di(2-ethylhexyl) phthalate (DEHP) is a plasticizer widely used in the manufacture of plastics, and it is an environmental contaminant. The specific growth rate (μ), maximum biomass (Xmax), biodegradation constant of DEHP (k), half-life (t1/2) of DEHP biodegradation and removal efficiency of DEHP, esterase and laccase specific activities, and enzymatic yield parameters were evaluated for Fusarium culmorum grown on media containing glucose and different concentrations of DEHP (0, 500 and 1000mg/L). The greatest μ and the largest Xmax occurred in media supplemented with 1000mg of DEHP/L. F. culmorum degraded 95% of the highest amount of DEHP tested (1000mg/L) within 60h of growth. The k and t1/2 were 0.024h(-1) and 28h, respectively, for both DEHP concentrations. The removal efficiency of DEHP was 99.8% and 99.9% for 1000 and 500mg/L, respectively. Much higher specific esterase activity than specific laccase activity was observed in all media tested. The compounds of biodegradation of DEHP were identified by GC-MS. A DEHP biodegradation pathway by F. culmorum was proposed on the basis of the intermolecular flow of electrons of the identified intermediate compounds using quantum chemical modeling. DEHP was fully metabolized by F. culmorum with butanediol as the final product. This fungus offers great potential in bioremediation of environments polluted with DEHP.

  17. Chemically modified graphite felt as an efficient cathode in electro-Fenton for p-nitrophenol degradation

    International Nuclear Information System (INIS)

    Highlights: • Chemically modified graphite felt was prepared using ethanol and hydrazine hydrate as reagents. • Carbon nanoparticles with functional groups were deposited on the surface after modification. • The electrochemical activity for ORR and H2O2 generation on the modified electrode was improved. • The cathode modification effictively improved the EF performance for pollutant degradation. - Abstract: A simple method with low-cost chemical reagents ethanol and hydrazine hydrate was used to modify graphite felt as the cathode for electro-Fenton (EF) application, using p-nitrophenol (p-Np) as the model pollutant. Characterized by scanning electron microscope, contact angle, Raman spectrum and X-ray photoelectron spectroscopy, the morphology and surface physicochemical properties after modification were observed considerably changed. After modification, some nanoparticles and oxygen and nitrogen-containing functional groups appeared on the cathode surface, which greatly improved the surface hydrophilic property and the electrocatalytic activity for oxygen reduction reaction. The effects led to the hydrogen peroxide accumulation on the modified cathode markedly increased to 175.8 mg L−1, while that on the unmodified one was only 67.5 mg L−1. p-Np of initial 50 mg L−1 could be completely removed by EF using the modified cathode, and the mineralization ratio reached 51.4%, more than 2 times of the pristine one. After 10 cycles, the mineralization ratio of the modified cathode was still above 45%, suggesting that the modification method can provide an effective approach to improve EF performance, and thus benefits to promote its environmental applications

  18. Soil organic degradation: bridging the gap between Rock-Eval pyrolysis and chemical characterization (CPMAS 13C NMR)

    Science.gov (United States)

    Albrecht, Remy; Sebag, David; Verrecchia, Eric

    2013-04-01

    -alkyl C, aromatic C and phenolic C and carbonyl-carboxyl C. Moreover, in order to avoid the influence of pedogenesis, we decided to use "less complex OM", i.e. compost samples. The choice to use compost samples has been dictated by the fact that i) composting processes are well described and referenced in the literature, and ii) these samples have already been studied previously (Albrecht, 2009). Significantly high correlations are observed between classes, or indices, from RE pyrolysis and main classes of organic matter detected by NMR e.g. F1 and labile / easily degradable components (alkyl C et O-alkyl C); F3/F4 and humified OM (aromatic C and phenolic C); R index (contributions of bio-macromolecules) and phenolic and aromatic C; I index (related to immature OM) and labile / easily degradable components (alkyl C et O-alkyl C). This work confirms the interest of RE pyrolysis in soil science (notably by using the R/I index ratio). Compost was an ideal model with a clear chronological evolution of organic matter. The next step consists of using more complex samples such as bulk soil samples. REFERENCES Albrecht, R., Joffre, R., Le Petit, J., Terrom, G., Périssol, C. 2009. Calibration of Chemical and Biological Changes in Cocomposting of Biowastes Using Near-Infrared Spectroscopy. Environmental Science & Technology, 43(3), 804-811. Copard, Y., Di-Govanni, C., Martaud, T., Alberic, P., Olivier, J.E. 2006. Using Rock-Eval 6 pyrolysis for tracking fossil organic carbon in modern environments: implications for the roles of erosion and weathering. Earth Surface Processes and Landforms, 31(2), 135-153. Disnar, J.R., Guillet, B., Keravis, D., Di-Giovanni, C., Sebag, D. 2003. Soil organic matter (SOM) characterization by Rock-Eval pyrolysis: scope and limitations. Organic Geochemistry, 34(3), 327-343. Kogel-Knabner, I. 2000. Analytical approaches for characterizing soil organic matter. Organic Geochemistry, 31(7-8), 609-625. Lafargue, E., Marquis, F., Pillot, D. 1998. Rock-Eval 6

  19. Determination of Nutritional Value and Digestibility and Degradability of Twigs in Four Tree Species through Chemical and in situ (Nylon Bags Techniques

    Directory of Open Access Journals (Sweden)

    H. Yosefifar

    2012-07-01

    Full Text Available This study has been conducted in order to determine nutritional value and digestibility and degradability of twigs in four tree species including Zelkova carpinifolia, Gleditchia caspica, Populus deltoids and Quercus castanaefolia through chemical and in situ techniques using 3 fistulated sheep in National Research Institute for Animal Science, IRAN. The experiment conducted based on Randomized Complete Block Design and obtained data were analyzed by software SAS and Neway. Chemical compounds (crude protein (CP, Neutral Detergent Fiber (NDF, Acid Detergent Fiber (ADF, Ether Extract (EE, Ash, Crude Fiber (CF, NFC(Non Fiber Carbohydrate, Nitrogen Free Extract (NFE and organic material (OM and degradation (dry matter and protein were determined. Amount of crude protein for 4 species are as follow Z. carpinifolia (11%, G. caspica (15.4%, P. deltoids (10.3% and Q. castanaefolia (9.5%, also amount of crude fiber in these trees are respectively 32.7, 18.6, 13.9 and 22.9%. Survey conducted on species’ degradation and on amounts of dry matter and protein which disappear after 0, 4, 8, 16, 24, 48, 72 and 96 hours. Results of degradation in dry matter and protein showed that extent of degradation has been an uptrend over time of incubation and it follows a similar trend at all times. The most degradation of dry matter (80.6% and protein (91.6% are related to G. caspica and the least degradation of dry matter (36% and protein (38.4% are related to Q. castanaefolia. Results showed that as a replacement or a complementary for alfalfa, the four considered tree species can provide some parts of food requirements by livestock through a correct programming.

  20. Chemical composition, anti-oxidative activity and in vitro dry matter degradability of Kinnow mandarin fruit waste

    Directory of Open Access Journals (Sweden)

    Ravleen Kour

    2014-10-01

    Full Text Available Aim: Fruit processing and consumption yield a significant amount of by-products as waste, which can be used as potential nutrient suppliers for livestock. “Kinnow” (Citrus nobilis Lour x Citrus deliciosa Tenora is one of the most important citrus fruit crops of North Indian States. Its residues are rich in carbohydrates but poor in protein and account for approximately 55-60% of the raw weight of the fruit. Present study assessed the chemical composition and anti-oxidative activity of Kinnow mandarin fruit waste (KMW and scrutinized the impact of dietary incorporation of variable levels of KMW on in vitro dry matter digestibility (IVDMD. Materials and Methods: Sun dried and ground KMW was analyzed for proximate composition, fibre fractions and calcium and phosphorus content. Antioxidant potential of KMW as total phenolic count and 1-diphenyl-2-picrylhydrazyl (DPPH scavenging activity was assayed in an alcoholic extract of KMW. The effect of inclusion of KMW at variable levels (0-40% in the isonitrogenous concentrate mixtures on in vitro degradability of composite feed (concentrate mixture:Wheat straw; 40:60 was also carried out. Results: KMW after sun-drying contained 92.05% dry matter. The crude protein content of 7.60% indicates it being marginal in protein content, whereas nitrogen free extract content of 73.69% suggests that it is primarily a carbonaceous feedstuff. This observation was also supported by low neutral detergent fiber and acid detergent fiber content of 26.35% and 19.50%, respectively. High calcium content (0.92% vis-à-vis low phosphorus content (0.08%, resulted in wide Ca:P ratio (11.5 in KMW. High anti-oxidative potential of KMW is indicated by total phenolic content values of 17.1±1.04 mg gallic acid equivalents/g and DPPH free radicle scavenging activity 96.2 μg/ml (effective concentration 50. Mean IVDMD% of all the composite rations was found to be comparable (p>0.05 irrespective of the level of KMW inclusion

  1. Effect of molecular weight on radiation chemical degradation yield of chain scission of γ-irradiated chitosan in solid state and in aqueous solution

    International Nuclear Information System (INIS)

    Chitosan A1, A2 and A3 with molecular weight of 471, 207 and 100 kDa respectively, produced from squid pen chitin was degraded by gamma rays in the solid state and in aqueous solution with various doses in air at ambient temperature. Effect of molecular weight on radiation chemical degradation yield of chain scission and degradation rate constants of γ-irradiated chitosan in solid state and in aqueous solution was investigated. The radiation chemical degradation yield G(s) and degradation rate values were calculated. The molecular weight changes were monitored by capillary viscometry method and the chemical structure changes were followed by UV analysis. The results showed that, the degradation of chitosan was faster in solution, than in solid state. The values of G(s) in solid state and in aqueous solution were respectively 1.1×10−8 mol/J and 0.074×10−7 mol/J for A1, 4.42×10−8 mol/J and 0.28×10−7 mol/J for A2 and 6.08×10−8 mol/J and 0.38×10−7 mol/J for A3. Degradation rate constants values ranged from 0.41×10−5 to 2.1×10−5 kGy−1 in solid state, whereas in solution they ranged from 13×10−5 to 68×10−5 kGy−1. The chitosan A3 was more sensitive to radiolysis than A1 and A2. The chain scission yield, G(s) and degradation rate constants seems to be greatly influenced by the initial molecular weight of the chitosan. Structural changes in irradiated chitosan are revealed by the apparition of absorption peaks at 261 and 295 nm, which could be attributed to the formation of carbonyl groups. In both conditions the peak intensity was higher in chitosan A3 than in A1 and A2, the oxidative products decreased with increasing molecular weight of chitosan. - Highlights: ► We investigated the effects of MW on G(s) value of γ-irradiated chitosan in solid and aqueous state. ► Chitosan with low molecular weight was more sensitive to radiolysis than high molecular weight. ► G(s) value and degradation rate seems to be greatly influenced by the

  2. Chemical degradation of proton conducting perflurosulfonic acid ionomer membranes studied by solid-state nuclear magnetic resonance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ghassemzadeh, L. [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D-70569 Stuttgart (Germany); Institut fuer Physikalische Chemie, Universitaet Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany); Marrony, M. [European Institute for Energy Research, Emmy-Noether-Strasse 11, D-76131 Karlsruhe (Germany); Barrera, R. [Edison, Via Giorgio La Pira, 2, I-10028 Trofarello (Italy); Kreuer, K.D.; Maier, J. [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D-70569 Stuttgart (Germany); Mueller, K. [Institut fuer Physikalische Chemie, Universitaet Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany)

    2009-01-15

    The degradation of two different types of perfluorinated polymer membranes, Nafion and Hyflon Ion, has been examined by solid-state {sup 19}F and {sup 13}C NMR spectroscopy. This spectroscopic technique is demonstrated to be a valuable tool for the study of the membrane structure and its alterations after in situ degradation in a fuel cell. The structural changes in different parts of the polymers are clearly distinguished, which provides unique insight into details of the degradation processes. The experimental NMR spectra prove that degradation mostly takes place within the polymer side chains, as reflected by the intensity losses of NMR signals associated with SO{sub 3}H, CF{sub 3}, OCF{sub 2} and CF groups. The integral degree of degradation is found to decrease with increasing membrane thickness while for a given thickness, Hyflon Ion appears to degrade less than Nafion. (author)

  3. 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.

  4. Coupled effects of the precipitation of secondary species on the mechanical behaviour and chemical degradation of concretes

    International Nuclear Information System (INIS)

    Sulfate attack of cement-based materials remains an important problem for the durability assessment of containers and disposal engineering barriers dedicated to the long-term storage of radioactive wastes since underground water which may reach these elements contains small quantities of sulfates (7-31 mmol/1). This work contributes to the study of sulfate-induced damage mechanisms, to their understanding and modelling. The experimental phases of this study aimed at the understanding of the different physico-chemical phenomena involved during an external sulfate attack at following their evolution and their impact on the transport and mechanical properties of the material. Leaching experiments in pure water and in a solution of sodium sulfate (with a sulfate content of 15 mmol/1), have been performed simultaneously on OPC paste (w/c 0,4)in order to allow a comparison of test results. The frequent analysis of the leachant has shown a consumption of sulfate ions by the matrix, proportional to the square rate of time. The use of X-Ray Diffraction on powders, obtained by scraping the calcium-depleted part of the samples, led a precise view of the cement paste mineralogy, during sulfate attack. The use of Scanning Electron Microscopy (SEM) and Energy Dispersive Spectrometer (EDS) confirmed the correctness of XRD profiles and brought important informations concerning cracking distribution and localisation. In addition, a visual monitoring of crack appearance and evolution completed the previous observations. Based on these experimental results, a simplified model accounting for the chemical degradation of cement paste in sulfated water has been proposed. A geochemical code, coupling the chemistry in solution with the reactive transport in porous media has been used for this purpose. The model accounts for the evolution of transport properties (diffusivity) associated with the calcium-depleting of the cement matrix and the precipitation of secondary phases (gypsum

  5. Fungal treatment of lignocellulosic biomass: Importance of fungal species, colonization and time on chemical composition and in vitro rumen degradability

    NARCIS (Netherlands)

    Kuijk, van S.J.A.; Sonnenberg, A.S.M.; Baars, J.J.P.; Hendriks, W.H.; Cone, J.W.

    2015-01-01

    The aim of this study is to evaluate fungal treatments to improve in vitro rumen degradability of lignocellulosic biomass. In this study four selective lignin degrading fungi, Ganoderma lucidum, Lentinula edodes, Pleurotus eryngii and Pleurotus ostreatus, were used to pre-treat lignocellulosic bioma

  6. Possible atmospheric lifetimes and chemical reaction mechanisms for selected HCFCs, HFCs, CH3CCl3, and their degradation products against dissolution and/or degradation in seawater and cloudwater

    Science.gov (United States)

    Wine, P. H.; Chameides, W. L.

    1990-01-01

    For a wide variety of atmospheric species including CO2, HNO3, and SO2, dissolution in seawater or cloudwater followed by hydrolysis or chemical reaction represents a primary pathway for removal from the atmosphere. In order to determine if this mechanism can also remove significant amounts of atmospheric chlorofluorocarbons (HCFC's), fluorocarbons (HFC's), and their degradation products, an investigation was undertaken as part of the Alternative Fluorocarbons Environmental Acceptability Study (AFEAS). In this investigation, the rates at which CHCl2CF3 (HCFC-123), CCl2FCH3 (HCFC-141b), CClF2CH3 (HCFC-142b), CHClF2 (HCFC-22), CHClFCF3 (HCFC-124) CH2FCF3 (HFC-134a) CHF2CH3 (HFC-152a), CHF2CF3 (HFC-125), and CH3CCl3 can be dissolved in the oceans and in cloudwater were estimated from the species' thermodynamic and chemical properties using simple mathematical formulations to simulate the transfer of gases from the atmosphere to the ocean or cloudwater. The ability of cloudwater and rainwater to remove gas phase degradation products of these compounds was also considered as was the aqueous phase chemistry of the degradation products. The results of this investigation are described.

  7. Effects of chemical compositions and ensiling on the biogas productivity and degradation rates of agricultural and food processing by-products.

    Science.gov (United States)

    Kafle, Gopi Krishna; Kim, Sang Hun

    2013-08-01

    The objective of this study was to investigate the effects of chemical compositions and ensiling on the biogas productivity and degradation rates of agricultural and food processing by-products (AFPBPs) using the biogas potential test. The AFPBPs were classified based on their chemical compositions (i.e., carbohydrate, protein and fat contents). The biogas and methane potentials of AFPBPs were calculated to range from 450 to 777 mL/g volatile solids (VS) and 260-543 mL/g VS, respectively. AFPBPs with high fat and protein contents produced significantly higher amounts of biogas than AFPBPs with high carbohydrate and low fat contents. The degradation rate was faster for AFPBPs with high carbohydrate contents compared to AFPBPs with high protein and fat contents. The lag phase and biogas production duration were lower when using ensiled AFPBPs than when using nonsilage AFPBPs. Among the four different silages tested, two silages significantly improved biogas production compared to the nonsilage AFPBPs.

  8. Degradation of cellulosic biomass and its subsequent utilization for the production of chemical feedstocks. Progress report, March 1-August 31, 1980

    Energy Technology Data Exchange (ETDEWEB)

    Wang, D. I.C.

    1980-09-01

    Progress is reported in this coordinated research program to effect the microbiological degradation of cellulosic biomass by anaerobic microorganisms possessing cellulolytic enzymes. Three main areas of research are discussed: increasing enzyme levels through genetics, mutations, and genetic manipulation; the direct conversion of cellulosic biomass to liquid fuel (ethanol); and the production of chemical feedstocks from biomass (acrylic acid, acetone/butanol, and acetic acid). (DMC)

  9. Influence of radiation on some physico-chemical properties of gum acacia. Mitigation of degradation by different class of antioxidants in LDPE expose to ionizing radiations

    International Nuclear Information System (INIS)

    Controlling of degradation in polysaccharide is also gaining impetus from commercial point of view. Comprehensive studies on the influence of ionizing radiation on the physico-chemical properties of polysaccharides are very important for their applications in different industries. The effect of gamma radiation on gum acacia has been studied and its effect on some physico-chemical properties, as measured by UV spectroscopy and viscometry has been discussed. The gum samples are irradiated in the range of 5 kGy to 25 kGy both in air and vacuum. Samples irradiated under vacuum shows colour stability while viscosity remain unaffected. (author)

  10. Protocol for the development of the Master Chemical Mechanism, MCM v3 (Part A: tropospheric degradation of non-aromatic volatile organic compounds

    Directory of Open Access Journals (Sweden)

    S. M. Saunders

    2003-01-01

    Full Text Available Kinetic and mechanistic data relevant to the tropospheric degradation of volatile organic compounds (VOC, and the production of secondary pollutants, have previously been used to define a protocol which underpinned the construction of a near-explicit Master Chemical Mechanism. In this paper, an update to the previous protocol is presented, which has been used to define degradation schemes for 107 non-aromatic VOC as part of version 3 of the Master Chemical Mechanism (MCM v3. The treatment of 18 aromatic VOC is described in a companion paper. The protocol is divided into a series of subsections describing initiation reactions, the reactions of the radical intermediates and the further degradation of first and subsequent generation products. Emphasis is placed on updating the previous information, and outlining the methodology which is specifically applicable to VOC not considered previously (e.g. a- and b-pinene. The present protocol aims to take into consideration work available in the open literature up to the beginning of 2001, and some other studies known by the authors which were under review at the time. Application of MCM v3 in appropriate box models indicates that the representation of isoprene degradation provides a good description of the speciated distribution of oxygenated organic products observed in reported field studies where isoprene was the dominant emitted hydrocarbon, and that the a-pinene degradation chemistry provides a good description of the time dependence of key gas phase species in a-pinene/NOX photo-oxidation experiments carried out in the European Photoreactor (EUPHORE. Photochemical Ozone Creation Potentials (POCP have been calculated for the 106 non-aromatic non-methane VOC in MCM v3 for idealised conditions appropriate to north-west Europe, using a photochemical trajectory model. The POCP values provide a measure of the relative ozone forming abilities of the VOC. Where applicable, the values are compared with

  11. Reactive Transport Modeling of Chemical and Isotope Data to Identify Degradation Processes of Chlorinated Ethenes in a Diffusion-Dominated Media

    Science.gov (United States)

    Chambon, J. C.; Damgaard, I.; Jeannottat, S.; Hunkeler, D.; Broholm, M. M.; Binning, P. J.; Bjerg, P. L.

    2012-12-01

    Chlorinated ethenes are among the most widespread contaminants in the subsurface and a major threat to groundwater quality at numerous contaminated sites. Many of these contaminated sites are found in low-permeability media, such as clay tills, where contaminant transport is controlled by diffusion. Degradation and transport processes of chlorinated ethenes are not well understood in such geological settings, therefore risk assessment and remediation at these sites are particularly challenging. In this work, a combined approach of chemical and isotope analysis on core samples, and reactive transport modeling has been used to identify the degradation processes occurring at the core scale. The field data was from a site located at Vadsby, Denmark, where chlorinated solvents were spilled during the 1960-70's, resulting in contamination of the clay till and the underlying sandy layer (15 meters below surface). The clay till is heavily contaminated between 4 and 15 mbs, both with the mother compounds PCE/TCE and TCA and the daughter products (DCE, VC, ethene, DCA), indicating the occurrence of natural dechlorination of both PCE/TCE and TCA. Intact core samples of length 0.5m were collected from the source zone (between 6 and 12 mbs). Concentrations and stable isotope ratios of the mother compounds and their daughter products, as well as redox parameters, fatty acids and microbial data, were analyzed with discrete sub-sampling along the cores. More samples (each 5 mm) were collected around the observed higher permeability zones such as sand lenses, sand stringers and fractures, where a higher degradation activity was expected. This study made use of a reactive transport model to investigate the appropriateness of several conceptual models. The conceptual models considered the location of dechlorination and degradation pathways (biotic reductive dechlorination or abiotic β-elimination with iron minerals) in three core profiles. The model includes diffusion in the matrix

  12. Proteomic strategy for identifying mollusc shell proteins using mild chemical degradation and trypsin digestion of insoluble organic shell matrix: a pilot study on Haliotis tuberculata.

    Science.gov (United States)

    Bédouet, Laurent; Marie, Arul; Berland, Sophie; Marie, Benjamin; Auzoux-Bordenave, Stéphanie; Marin, Frédéric; Milet, Christian

    2012-08-01

    A successful strategy for the identification of shell proteins is based on proteomic analyses where soluble and insoluble fractions isolated from organic shell matrix are digested with trypsin with the aim of generating peptides, which are used to identify novel shell proteins contained in databases. However, using trypsin as a sole degradative agent is limited by the enzyme's cleavage specificity and is dependent upon the occurrence of lysine and arginine in the shell protein sequence. To bypass this limitation, we investigated the ability of trifluoroacetic acid (TFA), a low-specificity chemical degradative agent, to generate clusters of analyzable peptides from organic shell matrix, suitable for database annotation. Acetic acid-insoluble fractions from Haliotis tuberculata shell were processed by trypsin followed by TFA digestion. The hydrolysates were used to annotate an expressed sequence tag library constructed from the mantle tissue of Haliotis asinina, a tropical abalone species. The characterization of sequences with repeat motifs featured in some of the shell matrix proteins benefited from TFA-induced serial cutting, which can result in peptide ladder series. Using the degradative specificities of TFA and trypsin, we were able to identify five novel shell proteins. This pilot study indicates that a mild chemical digestion of organic shell matrix combined with trypsin generates peptides suitable for proteomic analysis for better characterization of mollusc shell matrix proteins.

  13. Chemical composition and in sacco degradability of four varieties of cassava leaves grown in Southwestern Nigeria in the rumen of sheep.

    Science.gov (United States)

    Oni, A O; Onwuka, C F I; Arigbede, O M; Oni, O O; Anele, U Y; Yusuf, K O; Oduguwa, B O; Onifade, O S

    2010-10-01

    The nutritive value of leaves of four varieties of cassava (MS 6, TMS 30555, Idileruwa and TMS 30572) were studied through analysis of their chemical components and degradability of their dry matter (DM) and crude protein (CP) in the rumen of sheep. Results of the chemical analyses showed that the leaves of the four varieties contained different proportions of organic matter which was significantly (P leaves of MS 6 and Idileruwa had the highest concentrations of K (2.86) and a significantly lowest value (1.83) in TMS 30555. Also, the highest concentration of Ca and Fe (6.81 and 6.23) was recorded in MS 6. The highest Ca:P of 3.20 was obtained in TMS 30555. DM degradation characteristics and effective degradability varied significantly (P leaves could be ranked for their potential feeding value as TMS 30572 (71.5%) > MS6 (65.8%) > Idileruwa (63.0%) > TMS 30555 (50.4%). It is therefore concluded from this study that leaves of TMS 30572 and MS 6 have good potential as feed resources for ruminant animals and could be used in ruminant feeding as protein source ingredient.

  14. Protocol for the development of the Master Chemical Mechanism, MCM v3 (Part B: tropospheric degradation of aromatic volatile organic compounds

    Directory of Open Access Journals (Sweden)

    M. E. Jenkin

    2003-01-01

    Full Text Available Kinetic and mechanistic data relevant to the tropospheric degradation of aromatic volatile organic compounds (VOC have been used to define a mechanism development protocol, which has been used to construct degradation schemes for 18 aromatic VOC as part of version 3 of the Master Chemical Mechanism (MCM v3. This is complementary to the treatment of 107 non-aromatic VOC, presented in a companion paper. The protocol is divided into a series of subsections describing initiation reactions, the degradation chemistry to first generation products via a number of competitive routes, and the further degradation of first and subsequent generation products. Emphasis is placed on describing where the treatment differs from that applied to the non-aromatic VOC. The protocol is based on work available in the open literature up to the beginning of 2001, and some other studies known by the authors which were under review at the time. Photochemical Ozone Creation Potentials (POCP have been calculated for the 18 aromatic VOC in MCM v3 for idealised conditions appropriate to north-west Europe, using a photochemical trajectory model. The POCP values provide a measure of the relative ozone forming abilities of the VOC. These show distinct differences from POCP values calculated previously for the aromatics, using earlier versions of the MCM, and reasons for these differences are discussed.

  15. Protocol for the development of the Master Chemical Mechanism, MCM v3 (Part B: tropospheric degradation of aromatic volatile organic compounds

    Directory of Open Access Journals (Sweden)

    M. E. Jenkin

    2002-11-01

    Full Text Available Kinetic and mechanistic data relevant to the tropospheric degradation of aromatic volatile organic compounds (VOC have been used to define a mechanism development protocol, which has been used to construct degradation schemes for 18 aromatic VOC as part of version 3 of the Master Chemical Mechanism (MCM v3. This is complementary to the treatment of 107 non-aromatic VOC, presented in a companion paper. The protocol is divided into a series of subsections describing initiation reactions, the degradation chemistry to first generation products via a number of competitive routes, and the further degradation of first and subsequent generation products. Emphasis is placed on describing where the treatment differs from that applied to the non-aromatic VOC. The protocol is based on work available in the open literature up to the beginning of 2001, and some other studies known by the authors which were under review at the time. Photochemical Ozone Creation Potentials (POCP have been calculated for the 18 aromatic VOC in MCM v3 for idealised conditions appropriate to north-west Europe, using a photochemical trajectory model. The POCP values provide a measure of the relative ozone forming abilities of the VOC. These show distinct differences from POCP values calculated previously for the aromatics, using earlier versions of the MCM, and reasons for these differences are discussed.

  16. Persistent activation of NF-kappaB related to IkappaB's degradation profiles during early chemical hepatocarcinogenesis

    Directory of Open Access Journals (Sweden)

    García-Román Rebeca

    2007-04-01

    Full Text Available Abstract Background To define the NF-kappaB activation in early stages of hepatocarcinogenesis and its IkappaB's degradation profiles in comparison to sole liver regeneration. Methods Western-blot and EMSA analyses were performed for the NF-kappaB activation. The transcriptional activity of NF-kappaB was determined by RT-PCR of the IkappaB-α mRNA. The IkappaB's degradation proteins were determined by Western-blot assay. Results We demonstrated the persistent activation of NF-kappaB during early stages of hepatocarcinogenesis, which reached maximal level 30 min after partial hepatectomy. The DNA binding and transcriptional activity of NF-kappaB, were sustained during early steps of hepatocarcinogenesis in comparison to only partial hepatectomy, which displayed a transitory NF-kappaB activation. In early stages of hepatocarconogenesis, the IkappaB-α degradation turned out to be acute and transitory, but the low levels of IkappaB-β persisted even 15 days after partial hepatectomy. Interestingly, IkappaB-β degradation is not induced after sole partial hepatectomy. Conclusion We propose that during liver regeneration, the transitory stimulation of the transcription factor response, assures blockade of NF-kappaB until recovery of the total mass of the liver and the persistent NF-kappaB activation in early hepatocarcinogenesis may be due to IkappaB-β and IkappaB-α degradation, mainly IkappaB-β degradation, which contributes to gene transcription related to proliferation required for neoplasic progression.

  17. Lifetimes of organic photovoltaics: Design and synthesis of single oligomer molecules in order to study chemical degradation mechanisms

    DEFF Research Database (Denmark)

    Alstrup, J.; Norrman, K.; Jørgensen, M.;

    2006-01-01

    Degradation mechanisms in organic and polymer photovoltaics are addressed through the study of an organic photovoltaic molecule based on a single phenylene-vinylene-type oligomer molecule. The synthesis of such a model compound with different end-groups is presented that allows for assignment...

  18. Degradability of superparamagnetic nanoparticles in a model of intracellular environment: follow-up of magnetic, structural and chemical properties

    Energy Technology Data Exchange (ETDEWEB)

    Levy, Michael; Wilhelm, Claire; Gazeau, Florence [Laboratoire Matiere et Systemes Complexes, UMR 7057, CNRS and Universite Paris Diderot, 10 rue Alice Domon et Leonie Duquet, 75205 Paris cedex 13 (France); Lagarde, Florence [Universite de Lyon 1, Laboratoire des Sciences Analytiques, UMR 5180 CNRS-UCBL, bat CPE, 43, boulevard du 11 novembre 1918, 69622 Villeurbanne cedex (France); Maraloiu, Valentin-Adrian; Blanchin, Marie-Genevieve [Universite de Lyon 1, Laboratoire PMCN UMR 5586 CNRS-UCBL, 69622 Villeurbanne cedex (France); Gendron, Francois, E-mail: florence.gazeau@univ-paris-diderot.fr [Institut des Nanosciences de Paris (INSP) UMR 7588, CNRS and Universite Pierre et Marie Curie 110 rue de Lourmel, 75015 Paris (France)

    2010-10-01

    The unique magnetic properties of iron oxide nanoparticles have paved the way for various biomedical applications, such as magnetic resonance cellular imaging or magnetically induced therapeutic hyperthermia. Living cells interact with nanoparticles by internalizing them within intracellular acidic compartments. Although no acute toxicity of iron oxide nanoparticles has been reported up to now, the mechanisms of nanoparticle degradation by the cellular environment are still unknown. In the organism, the long term integrity and physical state of iron-based nanoparticles are challenged by iron homeostasis. In this study, we monitored the degradation of 7 nm sized maghemite nanoparticles in a medium mimicking the intracellular environment. Magnetic nanoparticles with three distinct surface coatings, currently evaluated as MRI contrast agents, were shown to exhibit different kinetics of dissolution at an acidic pH in the presence of a citrate chelating agent. Our assessment of the physical state of the nanoparticles during degradation revealed that the magnetic properties, size distribution and structure of the remaining nanocrystals were identical to those of the initial suspension. This result suggests a model for nanoparticle degradation with rapidly dissolved nanocrystals and a reservoir of intact nanoparticles.

  19. Heterogeneous photocatalytic degradation of the endocrine-disrupting chemical Benzophenone-3: Parameters optimization and by-products identification.

    Science.gov (United States)

    Zúñiga-Benítez, Henry; Aristizábal-Ciro, Carolina; Peñuela, Gustavo A

    2016-02-01

    Benzophenone-3 (BP3) is one of the most used UV filters. Its disruptive effect on the endocrine system of different living beings has been demonstrated by several research groups. Present work addresses on a photocatalytic degradation of BP3 using particles of titanium dioxide in aqueous solutions considering the effect of operating parameters such as pH, catalyst and pollutant initial concentrations, and the presence of hydrogen peroxide, acetonitrile and isopropanol in the solution. In this way, a face centered, central composite design was carried out for the identification of significant factors or interactions that allow the determination of the conditions under which the pollutant suffers the highest rates of degradation. A solution initial pH of 9.0, a TiO2 concentration of 1.184 g L(-1) and an H2O2 concentration of 128.069 mg L(-1) were established as the optimal conditions for the substrate removal. In aqueous solutions and low concentrations of the pollutant (photocatalysis with TiO2 is a potential method to remove BP3 from water. Additionally, tests using acetonitrile as solvent and isopropanol as hydroxyl radical (OH(.)) scavenger suggested that, OH(.) was the main agent responsible of substrate degradation. Finally, ten process by-products were identified and a degradation route was proposed. PMID:26686077

  20. Optical monitoring of surface processes relevant to thin film growth by chemical vapour deposition Oxidation; Surface degradation

    CERN Document Server

    Simcock, M N

    2002-01-01

    This thesis reports on the investigation of the use of reflectance anisotropy spectroscopy (RAS) as an in-situ monitor for the preparation and oxidation of GaAs(100) c(4x4) surfaces using a CVD 2000 MOCVD reactor. These surfaces were oxidised using air. It was found that it was possible to follow surface degradation using RA transients at 2.6eV and 4eV. From this data it was possible to speculate on the nature of the surface oxidation process. A study was performed into the rate of surface degradation under different concentrations of air, it was found that the relation between the air concentration and the surface degradation was complicated but that the behaviour of the first third of the degradation approximated a first order behaviour. An estimation of the activation energy of the process was then made, and an assessment of the potential use of the glove-box for STM studies which is an integral part of the MOCVD equipment was also made. Following this, a description is given of the construction of an inte...

  1. Chemical sporulation and germination: cytoprotective nanocoating of individual mammalian cells with a degradable tannic acid-FeIII complex

    Science.gov (United States)

    Lee, Juno; Cho, Hyeoncheol; Choi, Jinsu; Kim, Doyeon; Hong, Daewha; Park, Ji Hun; Yang, Sung Ho; Choi, Insung S.

    2015-11-01

    Individual mammalian cells were coated with cytoprotective and degradable films by cytocompatible processes maintaining the cell viability. Three types of mammalian cells (HeLa, NIH 3T3, and Jurkat cells) were coated with a metal-organic complex of tannic acid (TA) and ferric ion, and the TA-FeIII nanocoat effectively protected the coated mammalian cells against UV-C irradiation and a toxic compound. More importantly, the cell proliferation was controlled by programmed formation and degradation of the TA-FeIII nanocoat, mimicking the sporulation and germination processes found in nature.Individual mammalian cells were coated with cytoprotective and degradable films by cytocompatible processes maintaining the cell viability. Three types of mammalian cells (HeLa, NIH 3T3, and Jurkat cells) were coated with a metal-organic complex of tannic acid (TA) and ferric ion, and the TA-FeIII nanocoat effectively protected the coated mammalian cells against UV-C irradiation and a toxic compound. More importantly, the cell proliferation was controlled by programmed formation and degradation of the TA-FeIII nanocoat, mimicking the sporulation and germination processes found in nature. Electronic supplementary information (ESI) available: Experimental details, LSCM images, and SEM and TEM images. See DOI: 10.1039/c5nr05573c

  2. Chemical Potency and Degradation Products of Medications Stored Over 550 Earth Days at the International Space Station.

    Science.gov (United States)

    Wotring, Virginia E

    2016-01-01

    Medications degrade over time, and degradation is hastened by extreme storage conditions. Current procedures ensure that medications aboard the International Space Station (ISS) are restocked before their expiration dates, but resupply may not be possible on future long-duration exploration missions. For this reason, medications stored on the ISS were returned to Earth for analysis. This was an opportunistic, observational pilot-scale investigation to test the hypothesis that ISS-aging does not cause unusual degradation. Nine medications were analyzed for active pharmaceutical ingredient (API) content and degradant amounts; results were compared to 2012 United States Pharmacopeia (USP) requirements. The medications were two sleep aids, two antihistamines/decongestants, three pain relievers, an antidiarrheal, and an alertness medication. Because the samples were obtained opportunistically from unused medical supplies, each medication was available at only 1 time point and no control samples (samples aged for a similar period on Earth) were available. One medication met USP requirements 5 months after its expiration date. Four of the nine (44% of those tested) medications tested met USP requirements 8 months post expiration. Another three medications (33%) met USP guidelines 2-3 months before expiration. One compound, a dietary supplement used as a sleep aid, failed to meet USP requirements at 11 months post expiration. No unusual degradation products were identified. Limited, evidence-based extension of medication shelf-lives may be possible and would be useful in preparation for lengthy exploration missions. Only analysis of flight-aged samples compared to appropriately matched ground controls will permit determination of the spaceflight environment on medication stability.

  3. Chemical Potency and Degradation Products of Medications Stored Over 550 Earth Days at the International Space Station.

    Science.gov (United States)

    Wotring, Virginia E

    2016-01-01

    Medications degrade over time, and degradation is hastened by extreme storage conditions. Current procedures ensure that medications aboard the International Space Station (ISS) are restocked before their expiration dates, but resupply may not be possible on future long-duration exploration missions. For this reason, medications stored on the ISS were returned to Earth for analysis. This was an opportunistic, observational pilot-scale investigation to test the hypothesis that ISS-aging does not cause unusual degradation. Nine medications were analyzed for active pharmaceutical ingredient (API) content and degradant amounts; results were compared to 2012 United States Pharmacopeia (USP) requirements. The medications were two sleep aids, two antihistamines/decongestants, three pain relievers, an antidiarrheal, and an alertness medication. Because the samples were obtained opportunistically from unused medical supplies, each medication was available at only 1 time point and no control samples (samples aged for a similar period on Earth) were available. One medication met USP requirements 5 months after its expiration date. Four of the nine (44% of those tested) medications tested met USP requirements 8 months post expiration. Another three medications (33%) met USP guidelines 2-3 months before expiration. One compound, a dietary supplement used as a sleep aid, failed to meet USP requirements at 11 months post expiration. No unusual degradation products were identified. Limited, evidence-based extension of medication shelf-lives may be possible and would be useful in preparation for lengthy exploration missions. Only analysis of flight-aged samples compared to appropriately matched ground controls will permit determination of the spaceflight environment on medication stability. PMID:26546565

  4. Development of the HS-SPME-GC-MS/MS method for analysis of chemical warfare agent and their degradation products in environmental samples.

    Science.gov (United States)

    Nawała, Jakub; Czupryński, Krzysztof; Popiel, Stanisław; Dziedzic, Daniel; Bełdowski, Jacek

    2016-08-24

    After World War II approximately 50,000 tons of chemical weapons were dumped in the Baltic Sea by the Soviet Union under the provisions of the Potsdam Conference on Disarmament. These dumped chemical warfare agents still possess a major threat to the marine environment and to human life. Therefore, continue monitoring of these munitions is essential. In this work, we present the application of new solid phase microextraction fibers in analysis of chemical warfare agents and their degradation products. It can be concluded that the best fiber for analysis of sulfur mustard and its degradation products is butyl acrylate (BA), whereas for analysis of organoarsenic compounds and chloroacetophenone, the best fiber is a co-polymer of methyl acrylate and methyl methacrylate (MA/MMA). In order to achieve the lowest LOD and LOQ the samples should be divided into two subsamples. One of them should be analyzed using a BA fiber, and the second one using a MA/MMA fiber. When the fast analysis is required, the microextraction should be performed by use of a butyl acrylate fiber because the extraction efficiency of organoarsenic compounds for this fiber is acceptable. Next, we have elaborated of the HS-SPME-GC-MS/MS method for analysis of CWA degradation products in environmental samples using laboratory obtained fibers The analytical method for analysis of organosulfur and organoarsenic compounds was optimized and validated. The LOD's for all target chemicals were between 0.03 and 0.65 ppb. Then, the analytical method developed by us, was used for the analysis of sediment and pore water samples from the Baltic Sea. During these studies, 80 samples were analyzed. It was found that 25 sediments and 5 pore water samples contained CWA degradation products such as 1,4-dithiane, 1,4-oxathiane or triphenylarsine, the latter being a component of arsine oil. The obtained data is evidence that the CWAs present in the Baltic Sea have leaked into the general marine environment. PMID

  5. Degradation of cellulosic biomass and its subsequent utilization for the production of chemical feedstocks. Progress report, June 1-August 31, 1978

    Energy Technology Data Exchange (ETDEWEB)

    Wang, D.I.C.; Cooney, C.L.; Demain, A.L.; Gomez, R.F.; Sinskey, A.J.

    1978-08-01

    Studies concerning the cellobiose properties of Clostridium thermocellum were started to determine if the cellulose degradation end products can be enhanced for glucose (with a subsequent decrease in cellobiose). Implications of preliminary studies indicate that the cells or the enzyme(s) responsible for converting cellobiose to glucose can be manipulated environmentally and genetically to increase the final yield of glucose. The second area of effort is to the production of chemical feedstocks. Three fermentations have been identified for exploration. Preliminary reports on acrylic acid acetone/butanol, and acetic acid production by C. propionicum, C. acetobutylicum, and C. thermoaceticum, respectively, are included. (DMC)

  6. Development of the HS-SPME-GC-MS/MS method for analysis of chemical warfare agent and their degradation products in environmental samples.

    Science.gov (United States)

    Nawała, Jakub; Czupryński, Krzysztof; Popiel, Stanisław; Dziedzic, Daniel; Bełdowski, Jacek

    2016-08-24

    After World War II approximately 50,000 tons of chemical weapons were dumped in the Baltic Sea by the Soviet Union under the provisions of the Potsdam Conference on Disarmament. These dumped chemical warfare agents still possess a major threat to the marine environment and to human life. Therefore, continue monitoring of these munitions is essential. In this work, we present the application of new solid phase microextraction fibers in analysis of chemical warfare agents and their degradation products. It can be concluded that the best fiber for analysis of sulfur mustard and its degradation products is butyl acrylate (BA), whereas for analysis of organoarsenic compounds and chloroacetophenone, the best fiber is a co-polymer of methyl acrylate and methyl methacrylate (MA/MMA). In order to achieve the lowest LOD and LOQ the samples should be divided into two subsamples. One of them should be analyzed using a BA fiber, and the second one using a MA/MMA fiber. When the fast analysis is required, the microextraction should be performed by use of a butyl acrylate fiber because the extraction efficiency of organoarsenic compounds for this fiber is acceptable. Next, we have elaborated of the HS-SPME-GC-MS/MS method for analysis of CWA degradation products in environmental samples using laboratory obtained fibers The analytical method for analysis of organosulfur and organoarsenic compounds was optimized and validated. The LOD's for all target chemicals were between 0.03 and 0.65 ppb. Then, the analytical method developed by us, was used for the analysis of sediment and pore water samples from the Baltic Sea. During these studies, 80 samples were analyzed. It was found that 25 sediments and 5 pore water samples contained CWA degradation products such as 1,4-dithiane, 1,4-oxathiane or triphenylarsine, the latter being a component of arsine oil. The obtained data is evidence that the CWAs present in the Baltic Sea have leaked into the general marine environment.

  7. INFLUENCE OF STEAM PRESSURE ON THE PHYSICO-CHEMICAL PROPERTIES OF DEGRADED HEMICELLULOSES OBTAINED FROM STEAM-EXPLODED LESPEDEZA STALKS

    Directory of Open Access Journals (Sweden)

    Kun Wang

    2010-06-01

    Full Text Available Steam explosion pretreatment was used to release hemicelluloses from the stalks of Lespedeza crytobotrya, a potential woody biomass crop. Hemicelluloses from Lespedeza crytobotrya subjected to five different pretreatment severities were extracted with 60% aqueous ethanol solution containing 1% NaOH, characterized by component analysis, gel permeation chromatography (GPC, FT-IR, NMR spectroscopy, and thermal analysis, and compared with hemicelluloses obtained from untreated stalks. It was found that the hemicellulosic fractions mainly consisted of arabinoxylans and β-glucans or xyloglucans. Steam explosion pretreatment yielded noticeable degradation and debranching reactions, illustrated by a linear decrease of molecular weight and Ara/Xyl ratio with increasing severity. For further high-value utilization of the hemicellulosic polymers, steam explosion at 20 or 22.5 kg/m2 for 4 min is promising because of improved extraction efficiency and avoidance of over-drastic degradation of the polymers.

  8. Study of new optical fibres sensors for the follow-up of materials degradation and chemical species detection

    International Nuclear Information System (INIS)

    The aim of this work is to elaborate optical sensors able to follow in situ the degradation of metallic structures and the life cycle of polymers as well as their degradations. Thus, corrosion optical fiber sensors have been developed to follow in situ the degradation of metallic structures. They have been tested by two methods: an optical method and an electrochemical method. The idea is original, it consists to couple these two methods in correlating the parameters describing the optical process and those describing the electrochemical process. This approach allows to have a more accurate idea on the percentage of the corroded metallic surface. It has been shown too the feasibility of a gas and heavy metals sensor in including in the polymer matrix cryptophanes macromolecules able to trap selectively the gaseous molecules or in conditioning a new molecule of calix[4]arene functionalized for detecting metallic pollutants. Optical fiber sensors for the monitoring of high tension liquid dielectrics have been developed too. The presence of decomposition gas infiltrated in the dielectric liquid has been detected. The light propagation in an optical fiber has been modelled. Two approaches have been studied: a direct approach which consists to model the phenomena of light attenuation and a statistical approach where the light diffusion is described by a normal law. The two models are validated by the experiment and the coherence is very well. (O.M.)

  9. Effects of electron beam irradiation on chemical composition, antinutritional factors, ruminal degradation and in vitro protein digestibility of canola meal

    Energy Technology Data Exchange (ETDEWEB)

    Taghinejad-Roudbaneh, M., E-mail: mtaghinejad@iaut.ac.i [Department of Animal Science, Faculty of Agriculture, Islamic Azad University, Tabriz Branch, P.O. Box 51589, Tabriz (Iran, Islamic Republic of); Ebrahimi, S.R. [Department of Animal Science, Faculty of Agriculture, Shahr-e-Qods Branch, Islamic Azad University, P.O. Box 37515-374, Shahr-e-Qods (Iran, Islamic Republic of); Azizi, S. [Department of Clinical Sciences, Faculty of Veterinary Medicine, Urmia University, P.O. Box 57155-1177, Urmia (Iran, Islamic Republic of); Shawrang, P. [Nuclear Science and Technology Research Institute, Agricultural, Medical and Industrial Research School, Atomic Energy Organization of Iran, P.O. Box 31485-498, Karaj (Iran, Islamic Republic of)

    2010-12-15

    The aim of the present study was to determine the impact of electron beam (EB) irradiation at doses of 15, 30 and 45 kGy on the nutritional value of canola meal. The phytic acid and total glucosinolate content of EB-irradiated canola meal decreased as irradiation doses increased (P<0.01). From in situ results, irradiation of canola meal at doses of 45 kGy decreased (P<0.05) the effective degradibility of crude protein (CP) by 14%, compared with an untreated sample. In vitro CP digestibility of EB-irradiated canola meal at doses of 15 and 30 kGy was improved (P<0.05). Electrophoresis results showed that napin and cruciferin sub-units of 30 and 45 kGy EB-irradiated canola meal were more resistant to degradation, compared with an untreated sample. Electron beam irradiation was effective in protecting CP from ruminal degradation and reducing antinutritional factors of irradiated canola meal.

  10. Effects of electron beam irradiation on chemical composition, antinutritional factors, ruminal degradation and in vitro protein digestibility of canola meal

    Science.gov (United States)

    Taghinejad-Roudbaneh, M.; Ebrahimi, S. R.; Azizi, S.; Shawrang, P.

    2010-12-01

    The aim of the present study was to determine the impact of electron beam (EB) irradiation at doses of 15, 30 and 45 kGy on the nutritional value of canola meal. The phytic acid and total glucosinolate content of EB-irradiated canola meal decreased as irradiation doses increased ( P<0.01). From in situ results, irradiation of canola meal at doses of 45 kGy decreased ( P<0.05) the effective degradibility of crude protein (CP) by 14%, compared with an untreated sample. In vitro CP digestibility of EB-irradiated canola meal at doses of 15 and 30 kGy was improved ( P<0.05). Electrophoresis results showed that napin and cruciferin sub-units of 30 and 45 kGy EB-irradiated canola meal were more resistant to degradation, compared with an untreated sample. Electron beam irradiation was effective in protecting CP from ruminal degradation and reducing antinutritional factors of irradiated canola meal.

  11. Degradation of cellulosic biomass and its subsequent utilization for the production of chemical feedstocks. Final report, February 1, 1978-January 31, 1979

    Energy Technology Data Exchange (ETDEWEB)

    None

    1979-01-01

    This is a coordinated program to effect the microbiological degradation of cellulosic biomasses and will focus on the use of anaerobic microorganisms which possess cellulolytic enzyme. The studies will attempt to increase the enzyme levels through genetics, mutation and strain selection. In addition, the direct conversion from cellulosic biomasses to liquid fuel (ethanol) and/or soluble sugars by the cellulolytic, anaerobic organism is also within the scope of this program. Process and engineering scale-up, along with economic analyses, will be performed throughout the course of the program. The second area of our major effort is devoted to the production of chemical feedstocks. In particular, three fermentations have been identified for exploration. These are: acrylic acid, acetone/butanol and acetic acid. The main efforts in these fermentations will address means for the reduction of the cost of manufacturing for these large volume chemicals.

  12. The Environmental Fate Simulator: A tool for predicting the degradation pathways of organic chemicals in groundwater aquifers

    Science.gov (United States)

    Development of the Environmental Fate Simulator (EFS): • High throughput computational system for providing molecular and environmental descriptors for consumption by EF&T models Requires:  Knowledge of the process science controlling chemical fate and transport  The abil...

  13. Protocol for the development of the Master Chemical Mechanism, MCM v3 (Part A: tropospheric degradation of non-aromatic volatile organic compounds

    Directory of Open Access Journals (Sweden)

    S. M. Saunders

    2002-11-01

    Full Text Available Kinetic and mechanistic data relevant to the tropospheric degradation of volatile organic compounds (VOC, and the production of secondary pollutants, have previously been used to define a protocol which underpinned the construction of a near-explicit Master Chemical Mechanism. In this paper, an update to the previous protocol is presented, which has been used to define degradation schemes for 107 non-aromatic VOC as part of version 3 of the Master Chemical Mechanism (MCM v3. The treatment of 18 aromatic VOC is described in a companion paper. The protocol is divided into a series of subsections describing initiation reactions, the reactions of the radical intermediates and the further degradation of first and subsequent generation products. Emphasis is placed on updating the previous information, and outlining the methodology which is specifically applicable to VOC not considered previously (e.g. a- and b-pinene. The present protocol aims to take into consideration work available in the open literature up to the beginning of 2001, and some other studies known by the authors which were under review at the time. Application of MCM v3 in appropriate box models indicates that the representation of isoprene degradation provides a good description of the speciated distribution of oxygenated organic products observed in reported field studies where isoprene was the dominant emitted hydrocarbon, and that the a-pinene degradation chemistry provides a good description of the time dependence of key gas phase species in a-pinene/NOX photo-oxidation experiments carried out in the European Photoreactor (EUPHORE. Photochemical Ozone Creation Potentials (POCP have been calculated for the 106 non-aromatic non-methane VOC in MCM v3 for idealised conditions appropriate to north-west Europe, using a photochemical trajectory model. The POCP

  14. Chemical evolution of RNA under hydrothermal conditions and the role of thermal copolymers of amino acids for the prebiotic degradation and formation of RNA

    Science.gov (United States)

    Kawamura, K.; Nagahama, M.; Kuranoue, K.

    2005-01-01

    The roles of thermal copolymers of amino acids (TCAA) were studied for the prebiotic degradation of RNA. A weak catalytic ability of TCAA consisted of Glu, L-Ala, L-Val, L-Glu, L-Asp, and optionally L-His was detected for the cleavage of the ribose phosphodiester bond of a tetranucleotide (5'-dCrCdGdG) in aqueous solution at 80 degees C. The rate constants of the disappearance of 5'-dCrCdGdG were determined in aqueous solutions using different pH buffer and TCAA. The degradation rates were enhanced 1.3-3.0 times in the presence of TCAA at pH 7.5 and 8.0 at 80 degrees C, while the hydrolysis of oligoguanylate (oligo(G)) was accelerated about 1.6 times at pH 8.0. A weak inhibitory activity for the cleavage of oligo(G) was detected in the presence of 0.055 M TCAA-Std. On the other hand, our recent study on the influences of TCAA for the template-directed reaction of oligo(G) on a polycytidylic acid template showed that TCAA has an acceleration activity for the degradation of the activated nucleotide monomer and an acceleration activity for the formation of G5' ppG capped oligo(G). This series of studies suggest that efficient and selective catalytic or inhibitory activities for either the degradation or formation of RNA under hydrothermal conditions could have hardly emerged from the simple thermal condensation products of amino acids. A scenario is going to be deduced on the chemical evolution of enzymatic activities and RNA molecules concerning hydrothermal earth conditions. c2005 COSPAR. Published by Elsevier Ltd. All rights reserved.

  15. Lifetimes of organic photovoltaics: Using TOF-SIMS and 18O2 isotopic labelling to characterise chemical degradation mechanisms

    DEFF Research Database (Denmark)

    Norrman, K.; Krebs, Frederik C

    2006-01-01

    The lifetimes of organic photovoltaic cells based on conjugated polymer materials were studied. The device geometry was glass:ITO:PEDOT:PSS:C-12-PSV:C-60:aluminium. To characterise and elucidate the parts of the degradation mechanisms induced by molecular oxygen, 1802 isotopic labelling...... throughout the active layer with the largest concentration towards the aluminium electrode. For devices that had been kept in the dark oxygen species were only observed at the immediate interface between the aluminium and the organic layer. The isotopic labelling allowed us to demonstrate that the oxygen...

  16. Probabilistic human health risk assessment of degradation-related chemical mixtures in heterogeneous aquifers: Risk statistics, hot spots, and preferential channels

    Science.gov (United States)

    Henri, Christopher V.; Fernández-Garcia, Daniel; Barros, Felipe P. J.

    2015-06-01

    The increasing presence of toxic chemicals released in the subsurface has led to a rapid growth of social concerns and the need to develop and employ models that can predict the impact of groundwater contamination on human health risk under uncertainty. Monitored natural attenuation is a common remediation action in many contamination cases. However, natural attenuation can lead to the production of daughter species of distinct toxicity that may pose challenges in pollution management strategies. The actual threat that these contaminants pose to human health depends on the interplay between the complex structure of the geological media and the toxicity of each pollutant byproduct. This work addresses human health risk for chemical mixtures resulting from the sequential degradation of a contaminant (such as a chlorinated solvent) under uncertainty through high-resolution three-dimensional numerical simulations. We systematically investigate the interaction between aquifer heterogeneity, flow connectivity, contaminant injection model, and chemical toxicity in the probabilistic characterization of health risk. We illustrate how chemical-specific travel times control the regime of the expected risk and its corresponding uncertainties. Results indicate conditions where preferential flow paths can favor the reduction of the overall risk of the chemical mixture. The overall human risk response to aquifer connectivity is shown to be nontrivial for multispecies transport. This nontriviality is a result of the interaction between aquifer heterogeneity and chemical toxicity. To quantify the joint effect of connectivity and toxicity in health risk, we propose a toxicity-based Damköhler number. Furthermore, we provide a statistical characterization in terms of low-order moments and the probability density function of the individual and total risks.

  17. Chemical composition, fermentation characteristics, digestibility, and degradability of silages from two amaranth varieties (Kharkovskiy and Sem), corn, and an amaranth-corn combination.

    Science.gov (United States)

    Rahjerdi, N Karimi; Rouzbehan, Y; Fazaeli, H; Rezaei, J

    2015-12-01

    Amaranth ( sp.) is a C plant adapted to poor soils and regions with limited rainfall and high temperatures. The plant is characterized by a yield of up to 85 t/ha, CP concentration of up to 28.5% of DM, and DM digestibility of 59 to 79%, which may vary depending on the species and variety. The potential of this plant as a forage source for ruminants has not been completely considered. This study aimed at assessing the nutritive value of silages from corn (), 2 amaranth () varieties (var. Kharkovskiy and Sem), and an amaranth-corn combination by chemical composition, silage fermentation characteristics, in vivo digestibility, and in situ DM degradability. Treatments evaluated were ensiled corn var. hybrid SC 704 (EC), ensiled amaranth var. Kharkovskiy (EK), ensiled amaranth var. Sem (ES), ensiled corn-amaranth var. Kharkovskiy mixture, and ensiled corn-amaranth var. Sem mixture. Five sheep were used in a 5 × 5 Latin square design experiment to determine in vivo digestibility. The nylon bag technique was used to determine the in situ DM degradability using 3 ruminally fistulated sheep. Compared with EK, ES had greater ash-free NDF (NDFom) and CP concentrations. In comparison with EC, the ensiled amaranths and corn-amaranth mixtures had a greater ( amaranth with corn improved concentration of CP and digestibility of the mixed corn-amaranth silages and has the potential of completing corn in ruminant diets.

  18. Changes in the chemical composition and in vitro gas production of maize stover degraded with two edible mushrooms: Pleurotus sajor caju and Pleurotus pulmonarius

    International Nuclear Information System (INIS)

    Maize Stover was degraded using two white rot fungi: Pleurotus sajor pulmonarius, in a solid-state fermentation. In vitro gas production of the resulting substrates was carried out in 24h incubation and, the metabolisable energy, organic matter digestibility (OMD) and short chain fatty acid were predicted. The chemical composition and the crude fibre fractions were also determined. The result of the experiment shows that the crude protein (CP) increased from 3.6% in the control (UM) to 12.17% for Pleurotus sajor caju (PSM) and 19.63 for Pleurotus pulmonarius (PPM). This agrees with the report of Farkas. The crude fibre (CF) decreased ( P 0.05) while the rate of gas production (c h-1) was highest in the control (UM ) at 0.31ml/200mg DM. Short chain fatty acid and metabolisable energy were not different (P > 0.05). However, organic matter digestibility increased (P 4) produced also differed significantly. The outcome of this study shows that fungal degradation of maize stover enhanced the crude protein contents while fibre fractions were reduced, this suggest it that it can be used as protein supplement in the diet of ruminants. Further in vivo work is warranted to confirm this. (author)

  19. Trapping of muscle relaxant methocarbamol degradation product by complexation with copper(II) ion: Spectroscopic and quantum chemical studies

    Science.gov (United States)

    Mansour, Ahmed M.; Shehab, Ola R.

    2014-07-01

    Structural properties of methocarbamol (Mcm) were extensively studied both experimentally and theoretically using FT IR, 1H NMR, UV-Vis., geometry optimization, Mulliken charge, and molecular electrostatic potential. Stability arises from hyper-conjugative interactions, charge delocalization and H-bonding was analyzed using natural bond orbital (NBO) analysis. Mcm was decomposed in ethanol/water mixture at 80 °C to guaifenesin [(RS)-3-(2-methoxyphenoxy)propane-1,2-diol] and carbamate ion [NH2COO-], where the degradation mechanism was explained by trapping the carbamate ion via the complexation with copper(II) ion. The structure of the isolated complex ([Cu(NH2COO)2(H2O)]ṡ4H2O) was elucidated by spectral, thermal, and magnetic tools. Electronic spectra were discussed by TD-DFT and the descriptions of frontier molecular orbitals and the relocations of the electron density were determined. Calculated g-tensor values showed best agreement with experimental values from EPR when carried out using both the B3LYP and B3PW91 functional.

  20. CHEMICALS

    CERN Multimedia

    Medical Service

    2002-01-01

    It is reminded that all persons who use chemicals must inform CERN's Chemistry Service (TIS-GS-GC) and the CERN Medical Service (TIS-ME). Information concerning their toxicity or other hazards as well as the necessary individual and collective protection measures will be provided by these two services. Users must be in possession of a material safety data sheet (MSDS) for each chemical used. These can be obtained by one of several means : the manufacturer of the chemical (legally obliged to supply an MSDS for each chemical delivered) ; CERN's Chemistry Service of the General Safety Group of TIS ; for chemicals and gases available in the CERN Stores the MSDS has been made available via EDH either in pdf format or else via a link to the supplier's web site. Training courses in chemical safety are available for registration via HR-TD. CERN Medical Service : TIS-ME :73186 or service.medical@cern.ch Chemistry Service : TIS-GS-GC : 78546

  1. CHEMICAL COMPOSITION, CRYSTALLINITY, AND THERMAL DEGRADATION OF BLEACHED AND UNBLEACHED KENAF BAST (Hibiscus cannabinus PULP AND NANOFIBERS

    Directory of Open Access Journals (Sweden)

    Mehdi Jonoobi

    2009-05-01

    Full Text Available Kenaf (Hibiscus cannabinus nanofibers were isolated from unbleached and bleached pulp by a combination of chemical and mechanical treatments. The chemical methods were based on NaOH-AQ (anthraquinone and three-stage bleaching (DEpD processes, whereas the mechanical techniques involved refining, cryo-crushing, and high-pressure homogenization. The size and morphology of the obtained fibers were characterized by environmental scanning electron microscopy (ESEM and transmission electron microscopy (TEM, and the studies showed that the isolated nanofibers from unbleached and bleached pulp had diameters between 10-90 nm, while their length was in the micrometer range. Fourier transform infrared (FTIR spectroscopy demonstrated that the content of lignin and hemicellulose decreased in the pulping process and that lignin was almost completely removed during bleaching. Moreover, thermogravimetric analysis (TGA indicated that both pulp types as well as the nanofibers displayed a superior thermal stability as compared to the raw kenaf. Finally, X-ray analyses showed that the chemo-mechanical treatments altered the crystallinity of the pulp and the nanofibers: the bleached pulp had a higher crystallinity than its unbleached counterpart, and the bleached nanofibers presented the highest crystallinity of all the investigated materials.

  2. Degradation of organic pollutants and characteristics of activated sludge in an anaerobic/anoxic/oxic reactor treating chemical industrial wastewater

    Directory of Open Access Journals (Sweden)

    Dong Wang

    2014-09-01

    Full Text Available A laboratory-scale anaerobic/anoxic/oxic system operated at the hydraulic retention times (HRT of 20, 40, and 60 h with mixed liquor suspended solids (MLSS concentrations of 3 g/L and 6 g/L was considered for treating chemical industrial wastewater rich in complex organic compounds and total dissolved solids. Extending the HRT and increasing the MLSS concentration resulted in higher removal efficiency for chemical oxygen demand at 72%. Organic compounds in wastewater could be classified into easily-removed and refractory compounds during treatment. The easily-removed compounds consisted primarily of ethers, alcohols, and aldehydes, whereas the refractory compounds included mainly oxygen-containing heterocyclic and benzene-containing compounds. Results from energy-dispersive X-ray spectroscopy showed that several metal ions accumulated in activated sludge, particularly Fe(III. Fe accumulated mainly on the surface of sludge floc pellets and resulted in the compactness of activated sludge, which caused the values of mixed liquor volatile suspended solids /MLSS and sludge volume index to decrease.

  3. Bioassay-tracked temperature-stress-induced chemical degradation of bio-active wound healing antibacterial extract of Dissotis theifolia stem dispersed in a pharmaceutical cream and ointment

    Directory of Open Access Journals (Sweden)

    D C Odimegwu

    2011-03-01

    Full Text Available Summary: Owing to the present upsurge in the utilization of medicinal herbal preparations, routine quality control assessment for their continued efficacy and safety is essential if the products are to continue to maintain their pharmacological usefulness under harsh use and storage temperature normally experienced, particularly in the tropics. As herbal medicinal products are complex mixtures which originate from biological sources and are therefore very variable and difficult to characterize, great efforts are necessary to guarantee a constant and adequate quality of potency and safety through selection of an appropriate analytical method for the monitoring of the active ingredient content of such products. Dissotis theifolia is a commonly used plant in traditional herbal medicine for the treatment of several medical ailments, including topical bacterial infections, among several communities in Nigeria. In this present study, the quality control monitoring of the content of active ingredient of pharmaceutical cream and ointment containing the methanol extract of the stem exposed to variegated temperatures was established using a specific microbiological assay method. Results showed reduction of potency of the formulated extracts due to chemical degradation through the first order reaction pathway. The ointment formulation demonstrated a longer half-life and shelf-life being more stable than the cream.   Industrial relevance: Herbal medicine, a form of complimentary and alternative medicine, is becoming increasingly popular in both developing and developed countries. However, there appear to be limited data on their temperature-induce chemical stability/instability profile which correspondingly impinges on their efficacy and safety. In view of this study involving stem extract of D. theifolia formulated as cream and ointment, appropriate bioassay-based techniques can be employed in monitoring the potency of herbal preparations and can serve as

  4. Degradations and Rearrangement Reactions

    Science.gov (United States)

    Zhang, Jianbo

    This section deals with recent reports concerning degradation and rearrangement reactions of free sugars as well as some glycosides. The transformations are classified in chemical and enzymatic ways. In addition, the Maillard reaction will be discussed as an example of degradation and rearrangement transformation and its application in current research in the fields of chemistry and biology.

  5. Degradation of microbial polyesters.

    Science.gov (United States)

    Tokiwa, Yutaka; Calabia, Buenaventurada P

    2004-08-01

    Microbial polyhydroxyalkanoates (PHAs), one of the largest groups of thermoplastic polyesters are receiving much attention as biodegradable substitutes for non-degradable plastics. Poly(D-3-hydroxybutyrate) (PHB) is the most ubiquitous and most intensively studied PHA. Microorganisms degrading these polyesters are widely distributed in various environments. Although various PHB-degrading microorganisms and PHB depolymerases have been studied and characterized, there are still many groups of microorganisms and enzymes with varying properties awaiting various applications. Distributions of PHB-degrading microorganisms, factors affecting the biodegradability of PHB, and microbial and enzymatic degradation of PHB are discussed in this review. We also propose an application of a new isolated, thermophilic PHB-degrading microorganism, Streptomyces strain MG, for producing pure monomers of PHA and useful chemicals, including D-3-hydroxycarboxylic acids such as D-3-hydroxybutyric acid, by enzymatic degradation of PHB. PMID:15289671

  6. Studies on chemical composition and energy transformation in river Ganga at Kanpur and Varanasi due to environmental degradation.

    Science.gov (United States)

    Kumar, Amit; Jaiswal, Dolly; Watal, Geeta

    2009-05-01

    Impact of effluents discharged in Ganga through various sources on chemical composition, energy transformation rate and level of heavy metals was studied at Kanpur and Varanasi. The effluents were found to be nil in oxygen with acidic in oxygen with acidic to neutral pH (6.8-7.0) and having very high values of free CO2 (40-68 mg l(-1)), alkalinity (300.0-412.0 mg l(-1)), conductance (1082.0-1824.0 micromhos), total dissolved solids (542.0-912.0 mg l(-1)), hardness (228.0-330.0 mg l(-1)), chloride (42.0-60.0 mg l(-1)), organic matter (8.4-18.2 mg l(-1)) and BOD load (98.0-248.0 mg l(-1)). The heavy metals Cu, Cr, Cd, Pb and Zn were also quite high in the effluents (48.6-78.4, 54.0-84.6, 9.8-12.4, 72.4-84.0 and 148.6-284.0 microg l(-1) respectively). The discharged effluents induced severe reduction in oxygen (av. 0.82-3.4 mg l(-1)) and sharp increase in the level of free CO2 (av. 10.8-24.8 mg l(-1)), alkalinity (182.4-288.4 mg l(-1)), conductance (480.0- 628.0 mmhos), total dissolved solids (254.0-315.0 mg l(-1)), hardness (170.0-259.0 mg l(-1)), chloride (36.0-52.0 mg l(-1)), organic matter (4.8-6.8 mg l(-1)) and BOD load (36.4-58.4 mg l(-1)) at the discharge point (OF zones) from their comparatively much lower values before discharge (AOF zone). The rate of energy transformation and photosynthetic efficiency also reduced considerably at the discharge point (av. 1060-2101 calm(-2)day(-1) and 0.09-0.18%) from high values before discharged point (av. 4045-4733 calm(-2)day(-1) and 0.34-0.42%). The level of Cu, Cr, Cd, Pb and Zn also showed higher values at the discharged point (20.4-38.0, 22.4-54.8, 5.2-7.8, 30.8-72.0 and 64.8-120.8 microg l(-1) respectively). Considerable improvement was observed below the discharge (BOF zone). Comparison with earlier observation revealed that the magnitude of impact has reduced considerably after the regulation in the discharge both in he respect of chemical composition and energy transformation rates.

  7. Studies on chemical composition and energy transformation in river Ganga at Kanpur and Varanasi due to environmental degradation.

    Science.gov (United States)

    Kumar, Amit; Jaiswal, Dolly; Watal, Geeta

    2009-05-01

    Impact of effluents discharged in Ganga through various sources on chemical composition, energy transformation rate and level of heavy metals was studied at Kanpur and Varanasi. The effluents were found to be nil in oxygen with acidic in oxygen with acidic to neutral pH (6.8-7.0) and having very high values of free CO2 (40-68 mg l(-1)), alkalinity (300.0-412.0 mg l(-1)), conductance (1082.0-1824.0 micromhos), total dissolved solids (542.0-912.0 mg l(-1)), hardness (228.0-330.0 mg l(-1)), chloride (42.0-60.0 mg l(-1)), organic matter (8.4-18.2 mg l(-1)) and BOD load (98.0-248.0 mg l(-1)). The heavy metals Cu, Cr, Cd, Pb and Zn were also quite high in the effluents (48.6-78.4, 54.0-84.6, 9.8-12.4, 72.4-84.0 and 148.6-284.0 microg l(-1) respectively). The discharged effluents induced severe reduction in oxygen (av. 0.82-3.4 mg l(-1)) and sharp increase in the level of free CO2 (av. 10.8-24.8 mg l(-1)), alkalinity (182.4-288.4 mg l(-1)), conductance (480.0- 628.0 mmhos), total dissolved solids (254.0-315.0 mg l(-1)), hardness (170.0-259.0 mg l(-1)), chloride (36.0-52.0 mg l(-1)), organic matter (4.8-6.8 mg l(-1)) and BOD load (36.4-58.4 mg l(-1)) at the discharge point (OF zones) from their comparatively much lower values before discharge (AOF zone). The rate of energy transformation and photosynthetic efficiency also reduced considerably at the discharge point (av. 1060-2101 calm(-2)day(-1) and 0.09-0.18%) from high values before discharged point (av. 4045-4733 calm(-2)day(-1) and 0.34-0.42%). The level of Cu, Cr, Cd, Pb and Zn also showed higher values at the discharged point (20.4-38.0, 22.4-54.8, 5.2-7.8, 30.8-72.0 and 64.8-120.8 microg l(-1) respectively). Considerable improvement was observed below the discharge (BOF zone). Comparison with earlier observation revealed that the magnitude of impact has reduced considerably after the regulation in the discharge both in he respect of chemical composition and energy transformation rates. PMID:20120476

  8. Morphology induced photo-degradation study of low temperature, chemically derived ZnO/SnO2 heterostructure

    Science.gov (United States)

    Pal, Shreyasi; Maiti, Soumen; Chattopadhyay, Kalyan Kumar

    2016-05-01

    Rational construction of heterostructure is a key pathway to pursue highly active photocatalysts that also offers prospects to explore the relationship between structural aspect and photocatalytic efficiency. Here, we adopted a two-step wet chemical protocol for decoration of ZnO nanowires with SnO2 nanoclusters. ZnO nanowires were prepared by one pot ambient conditioned synthesis from commercial zinc powder. In sequence, synthesized ZnO nanowires were engineered with varying quantity SnO2 nanoclusters via low temperature hydrothermal method. Environmental remediation through catalytic activity of the samples was inspected taking two dyes having different ionic character (Methyl Orange and Rhodamine B) under UV irradiation where the optimized hybrid displayed better performance than mono component oxides. Enhancement in catalytic performance could be enlightened by the heterostructure formation at the ZnO/SnO2 interface which in turns prolonged photogenerated carrier separation and extend the photo response range. Furthermore, the photocatalysis performance by heterostructure could be recycled for several times without noticeable decrease in their catalytic activity.

  9. Growth-substrate induced performance degradation in chemically synthesized monolayer MoS2 field effect transistors

    International Nuclear Information System (INIS)

    We report on the electronic transport properties of single-layer thick chemical vapor deposition (CVD) grown molybdenum disulfide (MoS2) field-effect transistors (FETs) on Si/SiO2 substrates. MoS2 has been extensively investigated for the past two years as a potential semiconductor analogue to graphene. To date, MoS2 samples prepared via mechanical exfoliation have demonstrated field-effect mobility values which are significantly higher than that of CVD-grown MoS2. In this study, we will show that the intrinsic electronic performance of CVD-grown MoS2 is equal or superior to that of exfoliated material and has been possibly masked by a combination of interfacial contamination on the growth substrate and residual tensile strain resulting from the high-temperature growth process. We are able to quantify this strain in the as-grown material using pre- and post-transfer metrology and microscopy of the same crystals. Moreover, temperature-dependent electrical measurements made on as-grown and transferred MoS2 devices following an identical fabrication process demonstrate the improvement in field-effect mobility

  10. Growth-substrate induced performance degradation in chemically synthesized monolayer MoS{sub 2} field effect transistors

    Energy Technology Data Exchange (ETDEWEB)

    Amani, Matin; Chin, Matthew L.; Mazzoni, Alexander L.; Burke, Robert A.; Dubey, Madan, E-mail: madan.dubey.civ@mail.mil [Sensors and Electron Devices Directorate, US Army Research Laboratory, Adelphi, Maryland 20723 (United States); Najmaei, Sina; Ajayan, Pulickel M.; Lou, Jun [Department of Materials Science and Nanoengineering, Rice University, Houston, Texas 77005 (United States)

    2014-05-19

    We report on the electronic transport properties of single-layer thick chemical vapor deposition (CVD) grown molybdenum disulfide (MoS{sub 2}) field-effect transistors (FETs) on Si/SiO{sub 2} substrates. MoS{sub 2} has been extensively investigated for the past two years as a potential semiconductor analogue to graphene. To date, MoS{sub 2} samples prepared via mechanical exfoliation have demonstrated field-effect mobility values which are significantly higher than that of CVD-grown MoS{sub 2}. In this study, we will show that the intrinsic electronic performance of CVD-grown MoS{sub 2} is equal or superior to that of exfoliated material and has been possibly masked by a combination of interfacial contamination on the growth substrate and residual tensile strain resulting from the high-temperature growth process. We are able to quantify this strain in the as-grown material using pre- and post-transfer metrology and microscopy of the same crystals. Moreover, temperature-dependent electrical measurements made on as-grown and transferred MoS{sub 2} devices following an identical fabrication process demonstrate the improvement in field-effect mobility.

  11. Growth-substrate induced performance degradation in chemically synthesized monolayer MoS2 field effect transistors

    Science.gov (United States)

    Amani, Matin; Chin, Matthew L.; Mazzoni, Alexander L.; Burke, Robert A.; Najmaei, Sina; Ajayan, Pulickel M.; Lou, Jun; Dubey, Madan

    2014-05-01

    We report on the electronic transport properties of single-layer thick chemical vapor deposition (CVD) grown molybdenum disulfide (MoS2) field-effect transistors (FETs) on Si/SiO2 substrates. MoS2 has been extensively investigated for the past two years as a potential semiconductor analogue to graphene. To date, MoS2 samples prepared via mechanical exfoliation have demonstrated field-effect mobility values which are significantly higher than that of CVD-grown MoS2. In this study, we will show that the intrinsic electronic performance of CVD-grown MoS2 is equal or superior to that of exfoliated material and has been possibly masked by a combination of interfacial contamination on the growth substrate and residual tensile strain resulting from the high-temperature growth process. We are able to quantify this strain in the as-grown material using pre- and post-transfer metrology and microscopy of the same crystals. Moreover, temperature-dependent electrical measurements made on as-grown and transferred MoS2 devices following an identical fabrication process demonstrate the improvement in field-effect mobility.

  12. Coupled effects of the precipitation of secondary species on the mechanical behaviour and chemical degradation of concretes; Les effets couples de la precipitation d'especes secondaires sur le comportement mecanique et la degradation chimique des betons

    Energy Technology Data Exchange (ETDEWEB)

    Planel, D

    2002-06-01

    Sulfate attack of cement-based materials remains an important problem for the durability assessment of containers and disposal engineering barriers dedicated to the long-term storage of radioactive wastes since underground water which may reach these elements contains small quantities of sulfates (7-31 mmol/1). This work contributes to the study of sulfate-induced damage mechanisms, to their understanding and modelling. The experimental phases of this study aimed at the understanding of the different physico-chemical phenomena involved during an external sulfate attack at following their evolution and their impact on the transport and mechanical properties of the material. Leaching experiments in pure water and in a solution of sodium sulfate (with a sulfate content of 15 mmol/1), have been performed simultaneously on OPC paste (w/c 0,4)in order to allow a comparison of test results. The frequent analysis of the leachant has shown a consumption of sulfate ions by the matrix, proportional to the square rate of time. The use of X-Ray Diffraction on powders, obtained by scraping the calcium-depleted part of the samples, led a precise view of the cement paste mineralogy, during sulfate attack. The use of Scanning Electron Microscopy (SEM) and Energy Dispersive Spectrometer (EDS) confirmed the correctness of XRD profiles and brought important informations concerning cracking distribution and localisation. In addition, a visual monitoring of crack appearance and evolution completed the previous observations. Based on these experimental results, a simplified model accounting for the chemical degradation of cement paste in sulfated water has been proposed. A geochemical code, coupling the chemistry in solution with the reactive transport in porous media has been used for this purpose. The model accounts for the evolution of transport properties (diffusivity) associated with the calcium-depleting of the cement matrix and the precipitation of secondary phases (gypsum

  13. Environmental degradation as the result of NATO air-raids against Pancevo chemical plants - oil refinery/petrochemical plant/azotara fertilizer plant

    International Nuclear Information System (INIS)

    The long period of sanctions followed by the NATO air raids against the chemical plants of Pancevo caused ecological disaster of enormous proportions in the district, leaving the consequences to the population of the region,making it a transboundary issue of utmost urgency and importance. Due to the impossibility to organize the running under normal conditions during a decade of sanctions imposed on our country, the mentioned companies were constantly facing difficulties concerning the purchasing of the raw materials, devices and equipment since the export to FRY was banned. Thus the companies have been prevented from the realization of the environmental programs and plans including the introduction and implementation of new technologies having as the objectives the remediation of the already existing environmental problems, instead the environmental degradation was increased. During the period from 4th April-7th June 1999, Pancevo was targeted by the NATO on seven occasions. The area where the chemical plants are located was targeted with 35 missiles causing not only the damages but also endangered the environment of Pancevo and the consequences remain to be monitored in the coming years. Three employees of the Oil Refinery were killed at work while more than 50 were injured. Approximately 58.500 tons of crude oil, oil derivates, vinylchloride monomer and other petrochemical products and components were burnt in fire. Serious spills of approximately 5.000 tons of crude oil, oil derivates, 23.000 tons of 1,2 dichloroethane (EDC), 600 tons of HCl, 8 tons of mercury, 3000 tons of NaOH, 230 tons of ammonia water and ammonia and large quantities of other toxic substances contaminated the surrounding soil, ground water, the waste water canal and the river Danube.The sewerage systems were seriously damaged and blocked. A considerable damage was caused to the wastewater treatment facilities resulting in pollution of HIP-Azotara wastewater canal and the river Danube. The

  14. Use of a hand-portable gas chromatograph-toroidal ion trap mass spectrometer for self-chemical ionization identification of degradation products related to O-ethyl S-(2-diisopropylaminoethyl) methyl phosphonothiolate (VX)

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Philip A., E-mail: Smith.Philip.A@dol.gov [Uniformed Services University of the Health Sciences, Department of Preventive Medicine and Biometrics, 4301 Jones Bridge Road, Bethesda, MD, 20814 (United States); Lepage, Carmela R. Jackson [Defence R and D Canada - Suffield, Box 400, Station Main, Medicine Hat, Alberta, T1A 8K6 (Canada); Savage, Paul B. [Brigham Young University, Department of Chemistry and Biochemistry, Provo, UT, 84602 (United States); Bowerbank, Christopher R.; Lee, Edgar D. [Torion Technologies Inc., 796 East Utah Valley Drive, Suite 200, American Fork, UT, 84003 (United States); Lukacs, Michael J. [Defence R and D Canada - Suffield, Box 400, Station Main, Medicine Hat, Alberta, T1A 8K6 (Canada)

    2011-04-01

    The chemical warfare agent O-ethyl S-(2-diisopropylaminoethyl) methyl phosphonothiolate (VX) and many related degradation products produce poorly diagnostic electron ionization (EI) mass spectra by transmission quadrupole mass spectrometry. Thus, chemical ionization (CI) is often used for these analytes. In this work, pseudomolecular ([M+H]{sup +}) ion formation from self-chemical ionization (self-CI) was examined for four VX degradation products containing the diisopropylamine functional group. A person-portable toroidal ion trap mass spectrometer with a gas chromatographic inlet was used with EI, and both fixed-duration and feedback-controlled ionization time. With feedback-controlled ionization, ion cooling (reaction) times and ion formation target values were varied. Evidence for protonation of analytes was observed under all conditions, except for the largest analyte, bis(diisopropylaminoethyl)disulfide which yielded [M+H]{sup +} ions only with increased fixed ionization or ion cooling times. Analysis of triethylamine-d{sub 15} provided evidence that [M+H]{sup +} production was likely due to self-CI. Analysis of a degraded VX sample where lengthened ion storage and feedback-controlled ionization time were used resulted in detection of [M+H]{sup +} ions for VX and several relevant degradation products. Dimer ions were also observed for two phosphonate compounds detected in this sample.

  15. Shining light on the differences in molecular structural chemical makeup and the cause of distinct degradation behavior between malting- and feed-type barley using synchrotron FTIR microspectroscopy: a novel approach.

    Science.gov (United States)

    Yu, Peiqiang; Doiron, Kevin; Liu, Dasen

    2008-05-14

    The objective of this study was to use advanced synchrotron-sourced FTIR microspectroscopy (SFTIRM) as a novel approach to identify the differences in protein and carbohydrate molecular structure (chemical makeup) between these two varieties of barley and illustrate the exact causes for their significantly different degradation kinetics. Items assessed included (1) molecular structural differences in protein amide I to amide II intensities and their ratio within cellular dimensions, (2) molecular structural differences in protein secondary structure profile and their ratios, and (3) molecular structural differences in carbohydrate component peak profile. Our hypothesis was that molecular structure (chemical makeup) affects barley quality, fermentation, and degradation behavior in both humans and animals. Using SFTIRM, the protein and carbohydrate molecular structural chemical makeup of barley was revealed and identified. The protein molecular structural chemical makeup differed significantly between the two varieties of barleys. No difference in carbohydrate molecular structural chemical makeup was detected. Harrington was lower than Valier in protein amide I, amide II, and protein amide I to amide II ratio, while Harrington was relatively higher in model-fitted protein alpha-helix and beta-sheet, but lower in the others (beta-turn and random coil). These results indicated that it is the molecular structure of protein (chemical makeup) that may play a major role in the different degradation kinetics between the two varieties of barleys (not the molecular structure of carbohydrate). It is believed that use of the advanced synchrotron technology will make a significant step and an important contribution to research in examining the molecular structure (chemical makeup) of plant, feed, and seeds.

  16. Shining Light on the Differences in Molecular Structural Chemical Makeup and the Cause of Distinct Degradation Behavior Between Malting- and Feed- Type Barley Using Synchrotorn FTIR Microspectroscopy: A Novel Approach

    International Nuclear Information System (INIS)

    The objective of this study was to use advanced synchrotron-sourced FTIR microspectroscopy (SFTIRM) as a novel approach to identify the differences in protein and carbohydrate molecular structure (chemical makeup) between these two varieties of barley and illustrate the exact causes for their significantly different degradation kinetics. Items assessed included (1) molecular structural differences in protein amide I to amide II intensities and their ratio within cellular dimensions, (2) molecular structural differences in protein secondary structure profile and their ratios, and (3) molecular structural differences in carbohydrate component peak profile. Our hypothesis was that molecular structure (chemical makeup) affects barley quality, fermentation, and degradation behavior in both humans and animals. Using SFTIRM, the protein and carbohydrate molecular structural chemical makeup of barley was revealed and identified. The protein molecular structural chemical makeup differed significantly between the two varieties of barleys. No difference in carbohydrate molecular structural chemical makeup was detected. Harrington was lower than Valier in protein amide I, amide II, and protein amide I to amide II ratio, while Harrington was relatively higher in model-fitted protein a-helix and β-sheet, but lower in the others (β-turn and random coil). These results indicated that it is the molecular structure of protein (chemical makeup) that may play a major role in the different degradation kinetics between the two varieties of barleys (not the molecular structure of carbohydrate). It is believed that use of the advanced synchrotron technology will make a significant step and an important contribution to research in examining the molecular structure (chemical makeup) of plant, feed, and seeds.

  17. Purex diluent degradation

    Energy Technology Data Exchange (ETDEWEB)

    Tallent, O.K.; Mailen, J.C.; Pannell, K.D.

    1984-02-01

    The chemical degradation of normal paraffin hydrocarbon (NPH) diluents both in the pure state and mixed with 30% tributyl phosphate (TBP) was investigated in a series of experiments. The results show that degradation of NPH in the TBP-NPH-HNO/sub 3/ system is consistent with the active chemical agent being a radical-like nitrogen dioxide (NO/sub 2/) molecule, not HNO/sub 3/ as such. Spectrophotometric, gas chromatographic, mass spectrographic, and titrimetric methods were used to identify the degradation products, which included alkane nitro and nitrate compounds, alcohols, unsaturated alcohols, nitro alcohols, nitro alkenes, ketones, and carboxylic acids. The degradation rate was found to increase with increases in the HNO/sub 3/ concentration and the temperature. The rate was decreased by argon sparging to remove NO/sub 2/ and by the addition of butanol, which probably acts as a NO/sub 2/ scavenger. 13 references, 11 figures.

  18. How do polymers degrade?

    Science.gov (United States)

    Lyu, Suping

    2011-03-01

    Materials derived from agricultural products such as cellulose, starch, polylactide, etc. are more sustainable and environmentally benign than those derived from petroleum. However, applications of these polymers are limited by their processing properties, chemical and thermal stabilities. For example, polyethylene terephthalate fabrics last for many years under normal use conditions, but polylactide fabrics cannot due to chemical degradation. There are two primary mechanisms through which these polymers degrade: via hydrolysis and via oxidation. Both of these two mechanisms are related to combined factors such as monomer chemistry, chain configuration, chain mobility, crystallinity, and permeation to water and oxygen, and product geometry. In this talk, we will discuss how these materials degrade and how the degradation depends on these factors under application conditions. Both experimental studies and mathematical modeling will be presented.

  19. Purex diluent degradation

    International Nuclear Information System (INIS)

    The chemical degradation of normal paraffin hydrocarbon (NPH) diluents both in the pure state and mixed with 30% tributyl phosphate (TBP) was investigated in a series of experiments. The results show that degradation of NPH in the TBP-NPH-HNO3 system is consistent with the active chemical agent being a radical-like nitrogen dioxide (NO2) molecule, not HNO3 as such. Spectrophotometric, gas chromatographic, mass spectrographic, and titrimetric methods were used to identify the degradation products, which included alkane nitro and nitrate compounds, alcohols, unsaturated alcohols, nitro alcohols, nitro alkenes, ketones, and carboxylic acids. The degradation rate was found to increase with increases in the HNO3 concentration and the temperature. The rate was decreased by argon sparging to remove NO2 and by the addition of butanol, which probably acts as a NO2 scavenger. 13 references, 11 figures

  20. Weathering and Chemical Degradation of Methyl Eugenol and Raspberry Ketone Solid Dispensers for Detection, Monitoring, and Male Annihilation of Bactrocera dorsalis and Bactrocera cucurbitae (Diptera: Tephritidae) in Hawaii.

    Science.gov (United States)

    Vargas, Roger I; Souder, Steven K; Nkomo, Eddie; Cook, Peter J; Mackey, Bruce; Stark, John D

    2015-08-01

    Solid male lure dispensers containing methyl eugenol (ME) and raspberry ketone (RK), or mixtures of the lures (ME + RK), and dimethyl dichloro-vinyl phosphate (DDVP) were evaluated in area-wide pest management bucket or Jackson traps in commercial papaya (Carica papaya L.) orchards where both oriental fruit fly, Bactrocera dorsalis (Hendel), and melon fly, Bactrocera cucurbitae (Coquillett), are pests. Captures of B. dorsalis with fresh wafers in Jackson and bucket traps were significantly higher on the basis of ME concentration (Mallet ME [56%] > Mallet MR [31.2%] > Mallet MC [23.1%]). Captures of B. cucurbitae with fresh wafers in Jackson and bucket traps were not different regardless of concentration of RK (Mallet BR [20.1%] = Mallet MR [18.3%] = Mallet MC [15.9%]). Captures of B. dorsalis with fresh wafers, compared with weathered wafers, were significantly different after week 12; captures of B. cucurbitae were not significantly different after 16 wk. Chemical analyses revealed presence of RK in dispensers in constant amounts throughout the 16-wk trial. Degradation of both ME and DDVP over time was predicted with a high level of confidence by nonlinear asymptotic exponential decay curves. Results provide supportive data to deploy solid ME and RK wafers (with DDVP) in fruit fly traps for detection programs, as is the current practice with solid TML dispensers placed in Jackson traps. Wafers with ME and RK might be used in place of two separate traps for detection of both ME and RK responding fruit flies and could potentially reduce cost of materials and labor by 50%.

  1. Structural and chemical degradation mechanisms of pure YSZ and its components ZrO2 and Y2O3 in carbon-rich fuel gases.

    Science.gov (United States)

    Köck, Eva-Maria; Kogler, Michaela; Götsch, Thomas; Klötzer, Bernhard; Penner, Simon

    2016-05-25

    Structural and chemical degradation mechanisms of metal-free yttria stabilized zirconia (YSZ-8, 8 mol% Y2O3 in ZrO2) in comparison to its pure oxidic components ZrO2 and Y2O3 have been studied in carbon-rich fuel gases with respect to coking/graphitization and (oxy)carbide formation. By combining operando electrochemical impedance spectroscopy (EIS), operando Fourier-transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS), the removal and suppression of CH4- and CO-induced carbon deposits and of those generated in more realistic fuel gas mixtures (syngas, mixtures of CH4 or CO with CO2 and H2O) was examined under SOFC-relevant conditions up to 1273 K and ambient pressures. Surface-near carbidization is a major problem already on the "isolated" (i.e. Nickel-free) cermet components, leading to irreversible changes of the conduction properties. Graphitic carbon deposition takes place already on the "isolated" oxides under sufficiently fuel-rich conditions, most pronounced in the pure gases CH4 and CO, but also significantly in fuel gas mixtures containing H2O and CO2. For YSZ, a comparative quantification of the total amount of deposited carbon in all gases and mixtures is provided and thus yields favorable and detrimental experimental approaches to suppress the carbon formation. In addition, the effectivity and reversibility of removal of the coke/graphite layers was comparably studied in the pure oxidants O2, CO2 and H2O and their effective contribution upon addition to the pure fuel gases CO and CH4 verified.

  2. Structural and chemical degradation mechanisms of pure YSZ and its components ZrO2 and Y2O3 in carbon-rich fuel gases.

    Science.gov (United States)

    Köck, Eva-Maria; Kogler, Michaela; Götsch, Thomas; Klötzer, Bernhard; Penner, Simon

    2016-05-25

    Structural and chemical degradation mechanisms of metal-free yttria stabilized zirconia (YSZ-8, 8 mol% Y2O3 in ZrO2) in comparison to its pure oxidic components ZrO2 and Y2O3 have been studied in carbon-rich fuel gases with respect to coking/graphitization and (oxy)carbide formation. By combining operando electrochemical impedance spectroscopy (EIS), operando Fourier-transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS), the removal and suppression of CH4- and CO-induced carbon deposits and of those generated in more realistic fuel gas mixtures (syngas, mixtures of CH4 or CO with CO2 and H2O) was examined under SOFC-relevant conditions up to 1273 K and ambient pressures. Surface-near carbidization is a major problem already on the "isolated" (i.e. Nickel-free) cermet components, leading to irreversible changes of the conduction properties. Graphitic carbon deposition takes place already on the "isolated" oxides under sufficiently fuel-rich conditions, most pronounced in the pure gases CH4 and CO, but also significantly in fuel gas mixtures containing H2O and CO2. For YSZ, a comparative quantification of the total amount of deposited carbon in all gases and mixtures is provided and thus yields favorable and detrimental experimental approaches to suppress the carbon formation. In addition, the effectivity and reversibility of removal of the coke/graphite layers was comparably studied in the pure oxidants O2, CO2 and H2O and their effective contribution upon addition to the pure fuel gases CO and CH4 verified. PMID:27165763

  3. Waste package degradation from thermal and chemical processes in performance assessments for the Yucca Mountain disposal system for spent nuclear fuel and high-level radioactive waste

    International Nuclear Information System (INIS)

    This paper summarizes modeling of waste container degradation in performance assessments conducted between 1984 and 2008 to evaluate feasibility, viability, and assess compliance of a repository for spent nuclear fuel and high-level radioactive waste at Yucca Mountain, Nevada. As understanding of the Yucca Mountain disposal system increased, modeling of container degradation evolved from a component of the source term in 1984 to a separate module describing both container and drip shield degradation in 2008. A thermal module for evaluating the influence of higher heat loads from more closely packed, large waste packages was also introduced. In addition, a module for evaluating drift chemistry was added in later PAs to evaluate the potential for localized corrosion of the outer barrier of the waste container composed of Alloy 22, a highly corrosion-resistant nickel–chromium–tungsten–molybdenum alloy. The uncertainty of parameters related to container degradation contributed significantly to the estimated uncertainty of performance measures (cumulative release in assessments prior to 1995 and individual dose, thereafter). - Highlights: • Progression of container modeling from an assumption of complete failure before 1993 to a stochastic description after 1995 is described. • Introduction of thermal-hydrologic model to examine interaction between the engineered and natural barrier, and container degradation is described. • The introduction of a water chemistry module to evaluate the possibility of localized corrosion of the container is described. • The addition of seismic damage models to evaluate container damage from drift degradation and container movement is described

  4. Reactive transport modeling of chemical and isotope data to identify degradation processes of chlorinated ethenes in a diffusion-dominated media

    DEFF Research Database (Denmark)

    Chambon, Julie Claire Claudia; Damgaard, Ida; Jeannottat, Simon;

    zones in the low-permeability media. Previous studies have shown that degradation might be limited to high permeability zones in clay tills, thus limiting the applicability of remediation strategies based on enhanced biodegradation. Therefore the occurrence of degradation inside the clay matrix......Chlorinated ethenes are among the most widespread contaminants in the subsurface and a major threat to groundwater quality at numerous contaminated sites. Many of these contaminated sites are found in low-permeability media, such as clay tills, where contaminant transport is controlled by diffusion...

  5. Effect of chemical degradation on the mechanical properties of ethylene–propylene–diene (5-ethylidene-2-norbornene) terpolymer-BaSO4 nano composites

    International Nuclear Information System (INIS)

    Highlights: ► Time dependent degradation of EPDM and EPDM-barium sulphate nanocomposites studied. ► Primary process involved in acid degradation is decrosslinking via hydrolysis. ► Effect of attack traced by evaluating the % retention in properties. ► SEM was used to monitor the changes in surface topography due to attack of acid. -- Abstract: Time dependent degradation of the gum vulcanizates of ethylene propylene diene (EPDM) and EPDM-barium sulphate nano composites in sulphuric acid were studied. Impact of degradation on the mechanical properties of these composites was also evaluated. Gum compounds and nanocomposites cured with efficient vulcanisation system were subjected to an aggressive acidic medium containing 60% aqueous solution of sulphuric acid (H2SO4). The changes in functional groups were monitored using Fourier transform infrared spectroscopy (FTIR). The results reveal the formation of several oxygenated species on the EPDM rubber molecule due to acid attack; which is enhanced in the absence of barium sulphate nanofillers. Crosslink densities of acid aged samples were measured by the swelling method. An initial decrease in crosslink density as observed in EPDM gum vulcanizates is an indicative of hydrolytic attack at the crosslink sites, whereas the effect is less pronounced in nano composites. The effects of acid attack on mechanical properties were traced out by evaluating the percentage retention in tensile, elongation at break, compression set and abrasion resistance. For aged EPDM gum vulcanizates the retention in tensile showed a positive sign for a given increase in crosslink density, but on further increase of crosslink density due to combination of species formed during decrosslinking, tensile strength decreases. In the case of nano composites the retention in tensile properties was well around 100%. Scanning electron microscopy was used to monitor the changes in surface topography due to attack of acid and it well supports the

  6. Soil quality changes in land degradation as indicated by soil chemical, biochemical and microbiological properties in a karst area of southwest Guizhou, China

    Science.gov (United States)

    Zhang, Pingjiu; Li, Lianqing; Pan, Genxing; Ren, Jingchen

    2006-12-01

    Not only the nutritional status and biological activity but also the soil ecological functioning or soil health has been impacted profoundly by land degradation in the karst area of southwest China where the karst ecosystems are generally considered as extremely vulnerable to land degradation under intensified land-use changes. The objectives of this study are to elucidate the changes in overall soil quality by a holistic approach of soil nutritional, biological activity, and soil health indicators in the karst area as impacted by intense cultivation and vegetation degradation. Topsoil samples were collected on selected eco-tesserae in a sequence of land degradation in a karst area of southwest Guizhou in 2004. The soil nutrient pools of organic carbon (Corg), extractable extracellular carbon (Cext), total soil nitrogen (Nt), alkali-hydrolyzable nitrogen (Nah), total phosphorus (Pt), available phosphorus (Pa) were analyzed by wet soil chemistry. The soil biological properties were studied by means of measurements of microbial biomass carbon (both by fumigation-extraction, FE-Cmic, and by calculation from substrate-incubation respiration, SIR-Cmic) of respiration [respiration without addition of substrates, basal respiration (BR), and potential respiration (PR) with substrate-incubation] and of soil enzyme activities (invertase, urease, and alkaline phosphatase). Soil health status was assessed by simple indices of Cmic/Corg and BR/Cmic in conjunction with bacterial community structures determined by polymerase chain reaction and denaturing gradient gel electrophoresis. While the nutritional pool parameters, such as Corg and Cext, described basically the changes in soil life-supporting capacity with cultivation interference and vegetation declined, those parameters of biological activity such as FE-Cmic, SIR, and SIR-Cmic as well as bacterial community structures measured by molecular method evidenced well the changes in soil functioning for ecosystem health with

  7. Antifoam degradation testing

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, D. P. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River Ecology Lab. (SREL); Zamecnik, J. R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River Ecology Lab. (SREL); Newell, D. D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River Ecology Lab. (SREL); Williams, M. S. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River Ecology Lab. (SREL)

    2015-08-20

    This report describes the results of testing to quantify the degradation products resulting from the dilution and storage of Antifoam 747. Antifoam degradation is of concern to the Defense Waste Processing Facility (DWPF) due to flammable decomposition products in the vapor phase of the Chemical Process Cell vessels, as well as the collection of flammable and organic species in the offgas condensate. The discovery that hexamethyldisiloxane is formed from the antifoam decomposition was the basis for a Potential Inadequacy in the Safety Analysis declaration by the DWPF.

  8. Isolation and Degradation Characteristics of a New p-Toluenesulfonic Acid Degrading Strains from Chemical Plant Wastewater%化工厂废水中对甲苯磺酸降解菌的筛选及降解特性研究

    Institute of Scientific and Technical Information of China (English)

    沈洁; 李加友; 陆筑凤; 蔡丽玲

    2016-01-01

    以对甲苯磺酸为唯一碳源,从化工厂供试废水中筛选出对甲苯磺酸降解菌,经形态学观察和分子生物学鉴定,确定这种菌株为哈茨木霉菌,命名为哈茨木霉1228。利用固态发酵的方法制备哈茨木霉1228,培养物直接投入化工厂供试废水进行处理,结果发现:在pH=5、温度30℃时,处理7 h后,化工厂供试废水中对甲苯磺酸降解率可达45%。%The p-toluenesulfonic acid (p-TSA) degrading strain was isoloated from chemical plant wastewater, which can use p-TSA as the sole carbon nutrition for growth.The degrading strain was identified as Trichoderma harzianum based on the results of morphological observation and molecular biological analy-sis, and it was named Trichoderma harzianum 1228. Trichoderma harzianum 1228 was preparation for treat-ment of wastewater from chemical plant by solid state fermentation method. The results showed that, the degradation rate of p-TSA can reach 45%when the chemical plant was treated with 5 h at pH=5 and 30℃.

  9. Role of surfactant derived intermediates in the efficacy and mechanism for radiation chemical degradation of a hydrophobic azo dye, 1-phenylazo-2-naphthol

    Energy Technology Data Exchange (ETDEWEB)

    Das, Laboni [Radiation & Photochemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Chatterjee, Suchandra [Food Technology Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Naik, Devidas B. [Radiation & Photochemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Adhikari, Soumyakanti, E-mail: asoumya@barc.gov.in [Radiation & Photochemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2015-11-15

    Highlights: • Demonstration of the role of surfactant in the degradation of the hydrophobic dye. • First direct observation of the formation of “hydrazyl radical-parent” adduct. • Similar products obtained in the reaction of e{sup −}{sub aq} and ·OH radical in TX-100 medium. • Significant reduction in cytotoxicity of irradiated dye in aqueous–organic medium. • New mechanistic pathway could be delineated. - Abstract: A combined methodology involving gamma and pulse radiolysis, product analysis and toxicity studies has been adopted to comprehend the degradation process of a model hydrophobic azo dye, 1-phenylazo-2-naphthol, emphasizing the role of the surfactant, which is an integral part of textile waste. Two new and important findings are underlined in this article. The first is the direct attestation of the hydrazyl radical-parent adduct, formed in the reaction of the dye with e{sup −}{sub aq} followed by protonation and subsequent addition to the unreacted dye molecule. This has been confirmed from concentration dependent studies. Secondly, we have clearly shown that in the reaction of hydroxyl radical with the dye in Triton X-100 media, the initially produced TX radicals cause reductive degradation of the dye. Identification and detailed analysis of HPLC and GCMS data reveals that similar products are formed in both the reactions of e{sup −}{sub aq} and ·OH radicals. Moreover, the cytotoxicity of 10{sup −4} mol dm{sup −3} dye was found to be reduced significantly after irradiation. Thus, the present study not only depicts new pathways for the degradation of hydrophobic azo dye, but also demonstrates the role of a surfactant in the entire process.

  10. Role of surfactant derived intermediates in the efficacy and mechanism for radiation chemical degradation of a hydrophobic azo dye, 1-phenylazo-2-naphthol

    International Nuclear Information System (INIS)

    Highlights: • Demonstration of the role of surfactant in the degradation of the hydrophobic dye. • First direct observation of the formation of “hydrazyl radical-parent” adduct. • Similar products obtained in the reaction of e−aq and ·OH radical in TX-100 medium. • Significant reduction in cytotoxicity of irradiated dye in aqueous–organic medium. • New mechanistic pathway could be delineated. - Abstract: A combined methodology involving gamma and pulse radiolysis, product analysis and toxicity studies has been adopted to comprehend the degradation process of a model hydrophobic azo dye, 1-phenylazo-2-naphthol, emphasizing the role of the surfactant, which is an integral part of textile waste. Two new and important findings are underlined in this article. The first is the direct attestation of the hydrazyl radical-parent adduct, formed in the reaction of the dye with e−aq followed by protonation and subsequent addition to the unreacted dye molecule. This has been confirmed from concentration dependent studies. Secondly, we have clearly shown that in the reaction of hydroxyl radical with the dye in Triton X-100 media, the initially produced TX radicals cause reductive degradation of the dye. Identification and detailed analysis of HPLC and GCMS data reveals that similar products are formed in both the reactions of e−aq and ·OH radicals. Moreover, the cytotoxicity of 10−4 mol dm−3 dye was found to be reduced significantly after irradiation. Thus, the present study not only depicts new pathways for the degradation of hydrophobic azo dye, but also demonstrates the role of a surfactant in the entire process

  11. Identification of the specified impurities of silver sulfadiazine using a screening of degradation products in different stress physico-chemical media.

    Science.gov (United States)

    Cioroiu, Bogdan I; Lazar, Mihai I; Bello-López, Miguel A; Fernandez-Torres, Rut

    2013-11-15

    Determination of silver sulfadiazine degradation products in several stress media was carried out by high pressure liquid chromatography (HPLC) with diode array detector (DAD) and hybrid mass spectrometer triple quadrupole-linear trap. The optimal chromatographic method used a Hypercarb column with a stationary phase 100% carbon, a mobile phase composed by a mixture 45:55 formic acid 1% solution and acetonitrile and detection at 275 nm. Structure elucidation was carried out on the mass spectrometry system using same chromatographic conditions and based on MS/MS techniques. Under these conditions up to 9 possible impurities were demonstrated to be degradation products respecting silver sulfadiazine evolution under different stress conditions: temperature, acid, basic, oxidation, reduction and catalyzed photodegradation. Sulfacetamide, sulfanilic acid (4-aminobenzenesulfonic acid), aniline, pyrimidin-2-amine, 4-aminobenzenesulfonamide, 4-methylidenesulfanilaniline, 4-aminophenol, 4-amino-n-methyl benzenesulfonamide and benzenesulfonic acid were identified by mass spectrometry in order to cover the possible degradation paths of silver sulfadiazine. Kinetics were also evaluated to obtain the prediction of shelf life of the substance. The linearity domain for the method was between 0.0005 mg/ml and 0.25mg/ml for each compound. Recovery factors in accuracy determination were between 95 and 105% relative to target concentrations of silver sulfadiazine and the quantitation limit was 0.00025 mg/ml.

  12. Use of agro-industrial organic sludge amendment to remediate degraded soil: chemical and eco(geno)toxicological differences between fresh and stabilized sludge and establishment of application rates.

    Science.gov (United States)

    Chiochetta, Claudete G; Cotelle, Sylvie; Masfaraud, Jean-François; Toumi, Hela; Quaranta, Gaetana; Adani, Fabrizio; Radetski, Claudemir M

    2016-02-01

    Soil degraded by coal mining activities can be remediated by amendment with agro-industrial organic sludge. However, the environmental impacts associated with this management practice must be properly addressed. In this context, the objective of this study was to evaluate the eco(geno)toxicity of a fresh and a stabilized sludge before use in a laboratory soil remediation test. Chemical analysis of the complex mixtures (degraded soil, fresh sludge, and stabilized sludge) was carried out, as well as a battery of eco(geno)toxicity tests on microbiological enzymes (fluorescein hydrolysis), earthworms, and higher plants (including Vicia faba genotoxicity test), according to published methodologies. The results of these tests showed that fresh sludge was more toxic than sludge stabilized over 6 months toward earthworms and higher plants (lettuce, corn, and wild cabbage), while phyto(geno)toxicity tests with V. faba indicated the same genotoxicity levels for the two types of sludge. In the soil remediation simulation using different mixtures of degraded soil and stabilized sludge, the proportions of 50:50% (dry weight basis) provided the lowest phyto(geno)toxicity effects and this mixture can be used for the revegetation of the contaminated site.

  13. Effects of bio-chemical degradation on compression-swelling behaviour of solid waste%降解对垃圾土压缩回弹特性的影响

    Institute of Scientific and Technical Information of China (English)

    刘晓东; 施建勇; 高海

    2011-01-01

    采用人工配制的垃圾土样进行压缩回弹对比试验,通过对垃圾土中有机质含量和降解环境的控制,得到试样的压缩与回弹曲线,分析降解作用和有机质含量对垃圾土压缩及回弹特性的影响规律.结果表明,有机质含量越高,垃圾土的压缩性越强,回弹性也越强;有机质含量相同时,与抑制降解下垃圾土的压缩性相比,考虑降解时的垃圾土呈现更高压缩性,但表现出较小的回弹性.降解对垃圾土压缩的影响表现出前期影响大、后期影响较小的规律,这种变化与生化降解规律一致.建议分3段选取压缩系数:0~25、25~200和200 ~400 kPa,以全面描述垃圾土瞬时压缩、非线性压缩及线性压缩的能力.%Tests of compression-swelling were carried out with two group specimens under different organic content and different degradation conditions. The results show that the higher organic content is, the higher compressibility is, and the higher swelling it shows; Compared to specimen under restraining degradation condition, specimen with the same organic content under degradation condition shows higher compressibility and lower ability of swelling. The effect of bio-chemical degradation on compression behaviour of solid waste was higher in anterior period and lower in latter period, having the same rule as bio-chemical degradation. It is suggested that coefficient of compression should be selected in 3 phases; 0-25 kPa, 25 -200 kPa, 200 -400 kPa. This could indicate all-sided compressibility as instantaneous compression, nonlinear compression and liner compression. The study in this paper can provide some guidance to landfill design and filling construction.

  14. Degradation of cellulosic biomass and its subsequent utilization for the reproduction of chemical feedstocks. Progress report, December 1, 1977--February 28, 1978

    Energy Technology Data Exchange (ETDEWEB)

    Wang, D.I.C.; Cooney, C.L.; Demain, A.L.; Gomez, R.F.; Sinskey, A.J.

    1978-02-01

    Studies were performed to examine the utilization and hydrolysis of xylan, a major component of natural biomass materials. Experiments designed to examine the differential adsorption onto cellulose and xylan were inconclusive in proving that the xylan hydrolysis activity is distinct from cellulose hydrolysis activity. It is clear, however, that enzymes from C. thermocellum are able to effect xylan hydrolysis. A new biomass, thermally exploded lignocellulose Poplar, has undergone degradation studies by C. thermocellum. A concentrated effort has begun to examine the production of a liquid fuel (ethanol) directly from cellulosic biomass by Clostridium thermocellum. It was found that the pH has a significant influence on the extent of cellulose degradation as well as on the amount of products formed. To further our understandings on the production of ethanol by Clostridium thermocellum, a program was initiated to find anaerobes which could utilize the hemicelluloses from biomasses, as well as its ability to produce ethanol. The conditions of protoplasting C. thermocellum were examined and the optimum conditions established. A cellulase-hyperproducing mutant, AS-39, has been isolated. As-39 produces twice the cellulase activity of the parent as determined from measurements of both TNP-CMCase and Avicel-hydrolyzing activities. However, degradation studies using cellulosic substrates do not show enhanced rates. Studies on acrylic acid production have continued to proceed along several lines. Kinetic analysis has hypothesized that non-growing cells of Clostridium acetobutylicum should have the highest specific formation rates for acetone and n-butanol. Experimental studies indicated nongrowing cells can convert glucose to acetone and n-butanol with no other nutrient. The production of acetic acid by Clostridium thermoaceticum has focused on a mutant (S-2) which was isolated and found to tolerate higher concentrations of acetate.

  15. Variety diversity effect on the chemical composition and dry matter degradation characteristics of residue and by-products of oil palm fruits.

    Science.gov (United States)

    Bamikole, Musibau Adungbe; Ikhatua, Uamai Julius

    2009-06-01

    The materials palm press fibre (PPF), palm calyx (PCL) and palm oil sludge (POS) obtained from three varieties of oil palm: dura, oleifera and tenera were investigated for the effect of variety on their nutritive value. Analysis of proximate composition, cell wall fractions, some mineral concentration as well as in-situ dry matter degradation in the rumen of steers were carried out. Significant effects of materials (i.e. PPF, PCL and POS) as well as variety (i.e. dura, oleifera and tenera) were noticed in all the parameters studied except sodium (Na) and organic matter (OM) components. Crude protein (CP) values in all the varieties were lowest in PCL (3.15-5.48%) and highest in POS (9.02-10.02%), while crude fibre (CF) values were highest in PCL (33.00-46.19%) and lowest in POS (3.15-5.48%). The upper and lower values respectively for CP and CF in the materials were in most cases for the tenera variety. The cell wall fractions (NDF, ADF, Lignin, cellulose and hemicellulose) were all higher in PCL and lowest in POS. In the three varieties, POS had highest concentration of Mg (0.117-0.231 g/100 g), K (1.21-2.33 g/100 g) and Cu (75.07-87.34 mg/kg) but lowest content of Ca (0.016-0.089 g/100 g) while PPF had lowest concentration of Mg (0.031-0.039 g/100 g) and Cu (20.96-22.28 mg/kg). Iron (Fe, mg/kg) values were generally high, but highest in PCL (2015.41-4042.16). Dry matter degradability and effective degradability values were best in POS irrespective of the variety and least in PCL. Among the three varieties, dry matter degradation characteristics of tenera were the best and oleifera the least. Generally the residue and by-products irrespective of the variety of oil palm they are obtained from can be ranked for their nutritive value as POS > PPF > PCL, while nutritive ranking based on variety is tenera > dura > oleifera. Conclusively, POS and PPF from any variety of oil palm could be adopted directly as feed resources for ruminant livestock, while PCL will require

  16. A Comparison between Physico-Chemical Characteristics of the Degraded Palm Oil by Chicken Nuggets Coated with Sweet Pepper and Hot Pepper

    Directory of Open Access Journals (Sweden)

    Dan-Stefan Clonda

    2013-11-01

    Full Text Available Palm oil was selected from varieties of vegetable oils used in the food industry (especially in the food industry of "Fast Food" proved to be an oil with properties that can be maintained within acceptable limits for use after a reasonable time highly dependent on the type of food processed. It is known that frying is the most widely used process for the preparation of food both in the home and in industrial scale. The preference for this method of preparation of the food is due to the fact that it is a quick and convenient method from the point of view of time / output, and the food unique sensory properties, color, texture, consistency, taste and flavor are very popular with consumers. Degraded samples of the oils were analysed to ascertain the psysicochemical caracteristics (density, refractive index, acid and saponification values and percentage of water in comparison to the blank samples. The determinations conducted revealed elevated parameters due to the degradation compounds in the analysed samples.

  17. Chemical Characterization of Cellulose-degrading Streptomyces and Its Alkaline Extraction Fraction During Cellulose Degradation%纤维素降解过程中链霉菌菌体及其碱提取物组分研究

    Institute of Scientific and Technical Information of China (English)

    张伟; 窦森

    2014-01-01

    针对链霉菌降解纤维素后是否能形成腐殖质及其碱提取物组分是否为腐殖质组分这一微生物利用问题,采用液体摇床振荡培养实验,获得链霉菌降解纤维素形成的菌体,利用元素组成、差热分析和红外光谱法等现代仪器分析手段,初步研究了菌体的化学结构和碱提取物组分碳的分配状况。结果表明:随着培养时间的延长,培养后期(60 d)的链霉菌菌体产率显著增加;链霉菌菌体在化学结构上相似,与黑土胡敏酸(HA)相比,菌体的结晶度较低,芳香性较弱,热稳定性较强,脂肪碳链和含氧官能团含量较高;链霉菌经纤维素作用后形成的菌体,与黑土碱提取物(胡敏酸、富里酸)相比,“水溶性组分”较多,“碱溶组分”(类似于胡敏酸和富里酸的总和)较少,富含“碱溶酸不溶组分(类似于胡敏酸)”的物质增多,“水溶性组分”和“碱溶酸不溶组分”与纤维素和链霉菌的共同作用有关。以上结果表明,纤维素培养过程中链霉菌菌体与真正的黑土胡敏酸(HA)是有差别的。%Streptomyces are Gram-positive filamentous bacteria that live in the superficial layer of soil where they can degrade cellulose. They play important roles in producing the currently known antibiotics and many other bioactive molecules useful to human health and agri-culture. However, little is known about the characteristics of mycelia and alkaline extraction of Streptomyces sp. during cellulose degrada-tion. In the present study, sodium carboxymethyl cellulose(CMC)was used as a unique carbon source for the isolated strain Streptomyces sp. F in the liquid culture condition during the 60 day period. Carbon distribution, elemental compositions, thermostability and infrared structure of the alkali extraction of the harvested cells were further explored. The results showed that sodium carboxymethyl cellulose could be used

  18. Degradation of cellulosic biomass and its subsequent utilization for the production of chemical feedstocks. Progress report, December 1, 1978-February 28, 1979

    Energy Technology Data Exchange (ETDEWEB)

    Wang, D.I.C.; Cooney, C.L.; Demain, A.L.; Gomez, R.F.; Sinskey, A.J.

    1979-02-01

    The ongoing progress of a coordinated research program aimed at optimizing the biodegradation of cellulosic biomass to ethanol and chemical feedstocks is summarized. Growth requirements and genetic manipulations of clostridium thermocellum for selection of high cellulose producers are reported. The enzymatic activity of the cellulase produced by these organisms was studied. The soluble sugars produced from hydrolysis were analyzed. Increasing the tolerance of C. thermocellum to ethanol during liquid fuel production, increasing the rate of product formation, and directing the catabolism to selectively achieve high ethanol concentrations with respect to other products were studied. Alternative substrates for C. thermocellum were evaluated. Studies on the utilization of xylose were performed. Single stage fermentation of cellulose using mixed cultures of C. thermocellum and C. thermosaccharolyticum were studied. The study of the production of chemical feedstocks focused on acrylic acid, acetone/butanol, acetic acid, and lactic acid.

  19. Chemical State Mapping of Degraded B4C Control Rod Investigated with Soft X-ray Emission Spectrometer in Electron Probe Micro-analysis

    Science.gov (United States)

    Kasada, R.; Ha, Y.; Higuchi, T.; Sakamoto, K.

    2016-05-01

    B4C is widely used as control rods in light water reactors, such as the Fukushima Daiichi nuclear power plant, because it shows excellent neutron absorption and has a high melting point. However, B4C can melt at lower temperatures owing to eutectic interactions with stainless steel and can even evaporate by reacting with high-temperature steam under severe accident conditions. To reduce the risk of recriticality, a precise understanding of the location and chemical state of B in the melt core is necessary. Here we show that a novel soft X-ray emission spectrometer in electron probe microanalysis can help to obtain a chemical state map of B in a modeled control rod after a high-temperature steam oxidation test.

  20. Probabilistic human health risk assessment of degradation-related chemical mixtures in heterogeneous aquifers: risk statistics, hot spots, and preferential channels

    OpenAIRE

    Henri, Christopher Vincent; Fernández García, Daniel; Barros, Felipe de

    2015-01-01

    The increasing presence of toxic chemicals released in the subsurface has led to a rapid growth of social concerns and the need to develop and employ models that can predict the impact of groundwater contamination on human health risk under uncertainty. Monitored natural attenuation is a common remediation action in many contamination cases. However, natural attenuation can lead to the production of daughter species of distinct toxicity that may pose challenges in pollution management strateg...

  1. Visible-light sensitization of TiO2 photocatalysts via wet chemical N-doping for the degradation of dissolved organic compounds in wastewater treatment: a review

    International Nuclear Information System (INIS)

    Increased pollution of ground and surface water and emerging new micropollutants from a wide variety of industrial, municipal, and agricultural sources has increased demand on the development of innovative new technologies and materials whereby challenges associated with the provision of safe potable water can be addressed. Heterogeneous photocatalysis using visible-light sensitized TiO2 photocatalysts has attracted a lot of attention as it can effectively remove dissolved organic compound in water without generating harmful by-products. On this note, recent progress on visible-light sensitive TiO2 synthesis via wet chemical N-doping method is reviewed. In a typical visible-light sensitive TiO2 preparation via wet chemical methods, the chemical (e.g., N-doping content and states) and morphological properties (e.g., particle size, surface area, and crystal phase) of TiO2 in as-prepared resultants are sensitively dependent on many experimental variables during the synthesis. This has also made it very difficult to provide a universal guidance at this stage with a certainty for each variable of N-doping preparation. Instead of one-factor-at-a-time style investigation, a statistically valid parameter optimization investigation for general optima of photocatalytic activity will be certainly useful. Optimization of the preparation technique is envisaged to be beneficial to many environmental applications, i.e., dissolved organic compounds removal in wastewater treatment

  2. Separation,screening and application of efficient degradation microorganisms for improving COD removing rates from organic chemical wastewater%有机化工废水COD高效降解菌的分离筛选及应用

    Institute of Scientific and Technical Information of China (English)

    张为艳; 刘鹏程; 郑凤娟; 吴敏; 张文武

    2016-01-01

    18 strains of COD degrading bacteria have been separated and screened from high altitude salt lake sam-ples in Xinjiang Province by using organic chemical wastewater medium for treating wastewater,after mixed with 8 strains of bacteria which have high COD degrading rates. Compared to other ordinary activated sludge,the mixed strains show higher COD removing rate (86.3%). Being identified preliminarily by 16S rDNA analysis,it shows that these 8 strains of bacteria belong to the varieties,including Bacteroidetes,Firmicutes and Proteobacteria. The mixed bacterial floras are used in bio-aeration pool tests. The COD removing rate could reach 82.5%,by adding 0.75 g/L of urea as nitrogen sources. The COD degrading rate could be improved to 92.2%,by adding 0.5 g/L of tuna peptone.%利用有机化工废水培养基从新疆高海拔盐湖样品中分离筛选到COD降解菌18株,对COD降解率高的8株菌株混合后处理废水,与其他普通活性污泥相比,COD去除率更高(86.3%)。经16S rDNA初步鉴定,该8株菌分别属于拟杆菌门Bacteroidetes、厚壁菌门Firmicutes和变形菌门Proteobacteria。将该混合菌群用于生物曝气池试验,添加尿素0.75 g/L作为氮源,其COD降解率可达82.5%;添加金枪鱼蛋白胨0.5 g/L可使COD降解率提高到92.2%。

  3. Effect of chemical functionalization on the electrochemical properties of conducting polymers. Modification of polyaniline by diazonium ion coupling and subsequent reductive degradation

    Energy Technology Data Exchange (ETDEWEB)

    Acevedo, Diego F.; Rivarola, Claudia R.; Miras, Maria C. [Departamento de Quimica, Universidad Nacional de Rio Cuarto, Ruta Nacional 8, Km 601, X5804ZAB, Rio Cuarto, Cordoba (Argentina); Barbero, Cesar A., E-mail: cbarbero@exa.unrc.edu.a [Departamento de Quimica, Universidad Nacional de Rio Cuarto, Ruta Nacional 8, Km 601, X5804ZAB, Rio Cuarto, Cordoba (Argentina)

    2011-04-01

    The electrochemical properties of polyaniline (PANI) can be altered by coupling the polymer with aryldiazonium ions. The ions are synthesized by diazotization of aromatic primary amines (1-aminoanthraquinone, sulphadiazine and 4-cyanoaniline) bearing functional groups which are then linked to the polyaniline backbone. All materials produced are electroactive, suggesting that the reaction involves coupling of the diazonium ion with the aromatic rings and not nucleophilic substitution by the aminic nitrogen of PANI on the aryl cations. The electrochemical properties of the modified polymers are different to those of PANI, likely due to electronic and steric effects of the attached groups. Reductive degradation of the azo linkages, using dithionite ion, removes the attached moieties leaving primary amino groups attached to the polyaniline backbone. In that way, the effect of the attached groups on the electrochemical properties of PANI is eliminated. FTIR spectroscopy measurement of the different polymers supports the proposed mechanism. Using the method a polymer containing redox (anthraquinone) groups, which could be used for charge storage, is obtained. Additionally a material containing sulphadiazine moieties, which can be released in vivo by bacterial activity, is also produced. The molecule is a well-known sulfa drug with bacteriostatic activity. The reaction sequence seems to be of general application to modify polyanilines, by attaching functional groups, and then to produce a PANI backbone bearing primary amino groups. Evidence is presented on the kinetic control of attached group removal.

  4. Application of Microorganisms in the Degradation of Polluted Chemicals in Aquatic Environments%微生物在水环境污染物降解中的应用

    Institute of Scientific and Technical Information of China (English)

    彭燕; 蔡俊鹏

    2008-01-01

    Every year, waters on earth receive large quantities of wastewater from industry, agriculture, fish and poultry raising, and municipal sewage treatment plants. Consequently, the aquatic environment on the earth is under a serious challenge from a very large quantity of pollutants such as antibiotics, insecticides, herbicides, hydrocarbons, etc., contained in the domestic wastewater, industrial and agricultural waste water and illegal effluents. In particular, with the development of intensive aquiculture and poultry, the effluent pollution has recently become more and more serious with more attentions. Furthermore more and more chemical pollutants discharged into aquatic environment have been detected with the advancement of analytical techniques. These chemicals can cause toxic effects on water habitats after discharged into aquatic environment. However, microorganisms have many key functions in pollution control. In this review, applications of microorganism in the degradation of chemicals in aquatic environments are reviewed. It was concluded that most applications of microorganisms degrading chemicals focused on aquaculture waters, whereas other aquatic systems (such as river, lake, sea, coastal waters) have been scarcely studied.%每年有大量来自工业、农业、养殖业和城市污水处理厂的废水被排入到水环境中,因此,地球上的水环境面临大量来自生活废水、工农业废水、非法排放的废水及其它废水的污染物质(如抗生素、杀虫剂,除草剂、烃等)的严重挑战,特别是近年来随着集约化养殖的发展,废水污染问题日益突出,并且随着分析手段的进步,能够检测到被排入水环境中的化学污染物质也越来越多,这些化学污染物对水环境中的生物产生有害影响.但是,微生物在污染控制上具有许多重要的作用.因此,本文对微生物在水环境污染物降解中的应用进行了评论.结果表明微生物主要是应用

  5. Degradation of chlorophenols and alkylphenol ethoxylates, two representative textile chemicals, in water by advanced oxidation processes: the state of the art on transformation products and toxicity.

    Science.gov (United States)

    Karci, Akin

    2014-03-01

    Advanced oxidation processes based on the generation of reactive species including hydroxyl radicals are viable options in eliminating a wide array of refractory organic contaminants in industrial effluents. The assessment of transformation products and toxicity should be, however, the critical point that would allow the overall efficiency of advanced oxidation processes to be better understood and evaluated since some transformation products could have an inhibitory effect on certain organisms. This article reviews the most recent studies on transformation products and toxicity for evaluating advanced oxidation processes in eliminating classes of compounds described as "textile chemicals" from aqueous matrices and poses questions in need of further investigation. The scope of this paper is limited to the scientific studies with two classes of textile chemicals, namely chlorophenols and alkylphenol ethoxylates, whose use in textile industry is a matter of debate due to health risks to humans and harm to the environment. The article also raises the critical question: What is the state of the art knowledge on relationships between transformation products and toxicity? PMID:24216260

  6. Radiation degradation of silk

    Energy Technology Data Exchange (ETDEWEB)

    Ishida, Kazushige; Kamiishi, Youichi [Textile Research Institute of Gunma, Kiryu, Gunma (Japan); Takeshita, Hidefumi; Yoshii, Fumio; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    2001-03-01

    Silk fibroin powder was prepared from irradiated silk fibroin fiber by means of only physical treatment. Silk fibroin fiber irradiated with an accelerated electron beam in the dose range of 250 - 1000 kGy was pulverized by using a ball mill. Unirradiated silk fibroin fiber was not pulverized at all. But the more irradiation was increased, the more the conversion efficiency from fiber to powder was increased. The conversion efficiency of silk fibroin fiber irradiated 1000 kGy in oxygen was 94%. Silk fibroin powder shows remarkable solubility, which dissolved 57% into water of ambient temperature. It is a very interesting phenomenon that silk fibroin which did not treat with chemicals gets solubility only being pulverized. In order to study mechanism of solubilization of silk fibroin powder, amino acid component of soluble part of silk fibroin powder was analyzed. The more irradiation dose up, the more glycine or alanine degraded, but degradation fraction reached bounds about 50%. Other amino acids were degraded only 20% even at the maximum. To consider crystal construction of silk fibroin, it is suggested that irradiation on silk fibroin fiber selectively degrades glycine and alanine in amorphous region, which makes it possible to pulverize and to dissolve silk fibroin powder. (author)

  7. Chemical degradation and recycling of coloured polyethylene terephthalate waste%有色废弃PET材料化学回收新工艺

    Institute of Scientific and Technical Information of China (English)

    李雁; 郑楠; 郑玉斌

    2009-01-01

    为了解决有色废弃PET材料回收难的问题,促进资源循环利用,研究了有色PET以超临界甲醇技术进行解聚,并脱色提纯得到对笨二甲酸二甲酯的工艺流程.探讨了有色PET在超临界甲醇中的降解规律,并对脱色方案进行了筛选.探索了不同级别的PET材料解聚条件的差异.结果表明:纤维级材料在265℃,11 MPa下,超临界甲醇解聚30 min后,用溶解-热过滤-沉析的方法脱色提纯,对苯二甲酸二甲酯的产率可达到85%,纯度达到99.9%以上,白度达到87.5%;瓶片级材料呈现的解聚规律与纤维级变化趋势相同,但达到相同的解聚率,明显需要更长的反应时间.%In order to reduce the pollution produced by polyethylene terephthalate (PET) wastes and promote resource recycling, the degradation of PET in supercritical methanol yielding dimethyl terephthalate (DMT) was studied, and the decolorization methods for the product were investigated. It was found that fiber-grade PET can be depolymerized though supercritical methanol in about 30min at 265℃ and UMPa with DMT yield of nearly 85%, and the monomer has the purity to fiber-grade PET. While , it needs longer time for bottle-grade PET to reach the same depolymerization.

  8. Degradation of cellulosic biomass and its subsequent utilization for the production of chemical feedstocks. Progress report, June 1, 1977--August 31, 1977

    Energy Technology Data Exchange (ETDEWEB)

    Wang, D.I.C.; Cooney, C.L.; Demain, A.L.; Gomez, R.F.; Sinskey, A.J.

    1977-09-01

    Studies on the microbial degradation of cellulose biomass continues to be centered around Clostridium thermocellum. The effect of surfactants on growth and cellulase production by C. thermocellum was investigated. The effect of pH on growth and reducing sugar accumulation rate of Clostridium thermocellum on solka floc was evaluated. Activity of extracellular cellulase of Clostridium thermocellum ATCC 27405 was examined using TNP--CMC and Avicel as substrates. The pH optima are 5 and 4.5, respectively. Hydrolysis of either substrate is not inhibited by cellobiose, xylose, or glucose. The enzyme appears to be quite stable under reaction conditions at 60/sup 0/C. Thus far, regulation studies indicate that CMCase formation is not repressed by cellobiose. The search for plasmids in C. thermocellum was continued. The presence of plasmids was confirmed by cesium chloride ethidium bromide gradient centrifugation and electron microscopy. Two plasmids were detected, one with an approximate molecular weight of 1 x 10/sup 6/ daltons. Studies on the fermentation of lactic acid to propionic acid showed the pathway in C. propionicum to be simpler than in M. elsdenii and hence more amenable to manipulation for acrylate production. Using Lactobacillius delbrueckii, it was possible to convert glucose, cellobiose, and cellulose hydrolysates to lactic acid rapidly and quantitatively. Fermentations of C. acetobutylicum growing in soluble media were performed. Detailed studies of Clostridium thermoaceticum have shown that pH is the primary limiting factor in the production of acetic acid. pH-controlled fermentations indicated accumulations of over 30 gm/l of acetic acid.

  9. Degradation of cellulosic biomass and its subsequent utilization for the production of chemical feedstocks. Progress report, September 1-November 30, 1978

    Energy Technology Data Exchange (ETDEWEB)

    Wang, D.I.; Cooney, C.L.; Demain, A.L.; Gomez, R.F.; Sinskey, A.J.

    1978-11-01

    Studies on the accumulation of glucose during the fermentation of cellulose by Clostridium thermocellum are discussed. Production of ethanol and its relationship to growth rate in C. thermocellum is reported. Different biomasses were tested for ethanol yields. These included exploded poplar, sugar cane, bagasse, corn cobs, sweet gum, rice straw, and wheat straw. Thermophilic bacteria were tested to determine relationship of temperature to yield of ethanol. A preliminary report on isolating plaque forming emits derived from C. thermocellum is presented as well as the utilization of carbohydrates in nutrition. A cellulose enzyme is being purified from C. thermocellum. The production of chemical feedstocks by fermentation is reported. Acrylic acid, acetone/butanol, and acetic acid, produced by C. propionicum, C. acetobutylicum, and C. thermoaceticum, are discussed. (DC)

  10. Polysaccharide Degradation

    Science.gov (United States)

    Stone, Bruce A.; Svensson, Birte; Collins, Michelle E.; Rastall, Robert A.

    An overview of current and potential enzymes used to degrade polysaccharides is presented. Such depolymerases are comprised of glycoside hydrolases, glycosyl transferases, phosphorylases and lyases, and their classification, active sites and action patterns are discussed. Additionally, the mechanisms that these enzymes use to cleave glycosidic linkages is reviewed as are inhibitors of depolymerase activity; reagents which react with amino acid residues, glycoside derivatives, transition state inhibitors and proteinaceous inhibitors. The characterization of various enzymes of microbial, animal or plant origin has led to their widespread use in the production of important oligosaccharides which can be incorporated into food stuffs. Sources of polysaccharides of particular interest in this chapter are those from plants and include inulin, dextran, xylan and pectin, as their hydrolysis products are purported to be functional foods in the context of gastrointestinal health. An alternative use of degraded polysaccharides is in the treatment of disease. The possibility exists to treat bacterial exopolysaccharide with lyases from bacteriophage to produce oligosaccharides exhibiting bioactive sequences. Although this area is currently in its infancy the knowledge is available to investigate further.

  11. Chemical stability of amorphous materials: specific and general media effects in the role of water in the degradation of freeze-dried zoniporide.

    Science.gov (United States)

    Luthra, Suman A; Shalaev, Evgenyi Y; Medek, Ales; Hong, Jinyang; Pikal, Michael J

    2012-09-01

    The objective of the present work was to determine whether hydrolysis in a model lyophile was influenced by general media effects with water-changing properties of the medium or via a specific mechanism of water as a reactant. Four formulations of zoniporide and sucrose (1:10) were prepared with variable amounts of sorbitol [0%-25% (w/v) of total solids). These formulations were then equilibrated at 6% and 11% relative humidity using saturated salt solutions. The lyophile cakes were analyzed by differential scanning calorimetery (DSC), (isothermal microcalorimetry (IMC), solid- state nuclear magnetic resonance (ssNMR) spectroscopy, and ultraviolet-visible diffuse reflectance (DFR) spectroscopy. DSC and IMC were used to assess the global molecular mobility. ssNMR relaxation times were measured to access local mobility. The DFR was used to determine the solid-state acidity expressed as the Hammett acidity function. Stability of samples was evaluated at 40°C by monitoring potency and purity by high-performance liquid chromatography (HPLC). Results were interpreted in terms of the various roles of water: media effect, plasticization, polarity, and reactant. The kinetics of hydrolysis was observed to be correlated with either/both specific "chemical" effects, that is, water reactant as well as media effect, specifically global molecular mobility of the matrix. Increase in reaction rate with increase in water content is not linear and is a weaker dependence than in some hydrolytic reactions in organic solvents. A moderate amount of an inert plasticizer, sorbitol, conferred additional stabilization, possibly by restricting the amplitude and frequency of fast motions that are on a small length scale.

  12. Chemical stability of amorphous materials: specific and general media effects in the role of water in the degradation of freeze-dried zoniporide.

    Science.gov (United States)

    Luthra, Suman A; Shalaev, Evgenyi Y; Medek, Ales; Hong, Jinyang; Pikal, Michael J

    2012-09-01

    The objective of the present work was to determine whether hydrolysis in a model lyophile was influenced by general media effects with water-changing properties of the medium or via a specific mechanism of water as a reactant. Four formulations of zoniporide and sucrose (1:10) were prepared with variable amounts of sorbitol [0%-25% (w/v) of total solids). These formulations were then equilibrated at 6% and 11% relative humidity using saturated salt solutions. The lyophile cakes were analyzed by differential scanning calorimetery (DSC), (isothermal microcalorimetry (IMC), solid- state nuclear magnetic resonance (ssNMR) spectroscopy, and ultraviolet-visible diffuse reflectance (DFR) spectroscopy. DSC and IMC were used to assess the global molecular mobility. ssNMR relaxation times were measured to access local mobility. The DFR was used to determine the solid-state acidity expressed as the Hammett acidity function. Stability of samples was evaluated at 40°C by monitoring potency and purity by high-performance liquid chromatography (HPLC). Results were interpreted in terms of the various roles of water: media effect, plasticization, polarity, and reactant. The kinetics of hydrolysis was observed to be correlated with either/both specific "chemical" effects, that is, water reactant as well as media effect, specifically global molecular mobility of the matrix. Increase in reaction rate with increase in water content is not linear and is a weaker dependence than in some hydrolytic reactions in organic solvents. A moderate amount of an inert plasticizer, sorbitol, conferred additional stabilization, possibly by restricting the amplitude and frequency of fast motions that are on a small length scale. PMID:22461087

  13. Degradation and Improvement of Argiudolls in Centre Santa Fe (Argentina): Changes in Physical and Chemical Soil Properties and in its Productive Capacity Using a sSmulation Model of Crop Growth

    Science.gov (United States)

    Pilatti, M. A.; Marano, R.; Felli, O.; Alesso, A.; Carrizo, M. E.; Miretti, M. C.

    2012-04-01

    Traditional tillage without adequate crop rotation and restoration of nutrients had generated degradation of the soils in Santa Fe. For this reason, it is important to find alternative systems to improve them. The A horizon of a typical Argiudoll of the centre of Santa Fe was chosen in 1983 and 2003 to evaluate: (to) physical and chemical properties of the natural soil (SN), (b) level of deterioration or improvement of those properties due to the management system (LC: traditional till during 50 years with the last 15 years of wheat-soya; RAG: crop-grass rotation under no-till with partial reposition of N, P and S), (c) productive capacity (CP) of the SN and the soil changes according to its management (LC and RAG). Soil data were introduced into a model of crop production (FitoSim), using corn as pattern and 30 years of meteorological data, to evaluate the effect of the soil use on the productive capacity. LC and RAG significantly differ from SN. The former have smaller values of CO, Nt, P e, pH, Ca, K, soil bulk density, relative aggregates stability, least limiting water range and crust infiltration. However the indexes are worse in LC. RAG has greater values of P, Nt and particulate N. The mean potential yield was 16200 kg/ha. The index of production capacity of SN was 75%, i.e. the limitations of the soil and rain only allow taking advantage of 75% of the environment potential capacity. In LC that loss reached 72%. The loss of productive capacity of the evaluated management systems was 21 and 69% for RAG and LC, standing out that although RAG is degraded with regard to the SN, however it is a more conservationist management system that LC. Subsidiado por CA+ID 2009 (UNL) 12/C114; SECTEI- Ley23877-09-04; INTA PNECO-093012

  14. Degradation mechanisms in organic photovoltaic devices

    NARCIS (Netherlands)

    Grossiord, N.; Kroon, J.M.; Andriessen, H.A.J.M.; Blom, P.W.M.

    2012-01-01

    In the present review, the main degradation mechanisms occurring in the different layer stacking (i.e. photoactive layer, electrode, encapsulation film, interconnection) of polymeric organic solar cells and modules are discussed. Bulk and interfacial, as well as chemical and physical degradation mec

  15. STRUCTURAL PERFORMANCE OF DEGRADED REINFORCED CONCRETE MEMBERS.

    Energy Technology Data Exchange (ETDEWEB)

    Braverman, J.I.; Miller, C.A.; Ellingwood, B.R.; Naus, D.J.; Hofmayer, C.H.; Bezler, P.; Chang, T.Y.

    2001-03-22

    This paper describes the results of a study to evaluate, in probabilistic terms, the effects of age-related degradation on the structural performance of reinforced concrete members at nuclear power plants. The paper focuses on degradation of reinforced concrete flexural members and shear walls due to the loss of steel reinforcing area and loss of concrete area (cracking/spalling). Loss of steel area is typically caused by corrosion while cracking and spalling can be caused by corrosion of reinforcing steel, freeze-thaw, or aggressive chemical attack. Structural performance in the presence of uncertainties is depicted by a fragility (or conditional probability of failure). The effects of degradation on the fragility of reinforced concrete members are calculated to assess the potential significance of various levels of degradation. The fragility modeling procedures applied to degraded concrete members can be used to assess the effects of degradation on plant risk and can lead to the development of probability-based degradation acceptance limits.

  16. Enzymatic degradation of polycaprolactone-gelatin blend

    Science.gov (United States)

    Banerjee, Aditi; Chatterjee, Kaushik; Madras, Giridhar

    2015-04-01

    Blends of polycaprolactone (PCL), a synthetic polymer and gelatin, natural polymer offer a optimal combination of strength, water wettability and cytocompatibility for use as a resorbable biomaterial. The enzymatic degradation of PCL, gelatin and PCL-gelatin blended films was studied in the presence of lipase (Novozym 435, immobilized) and lysozyme. Novozym 435 degraded the PCL films whereas lysozyme degraded the gelatin. Though Novozym 435 and lysozyme individually could degrade PCL-gelatin blended films, the combination of these enzymes showed the highest degradation of these blended films. Moreover, the enzymatic degradation was much faster when fresh enzymes were added at regular intervals. The changes in physico-chemical properties of polymer films due to degradation were studied by scanning electron microscopy, Fourier transform infrared spectroscopy and differential scanning calorimetry. These results have important implications for designing resorbable biomedical implants.

  17. Cyclopiazonic acid degradation by aqueous ozone

    OpenAIRE

    Silva, Otniel Freitas; Venâncio, Armando

    2011-01-01

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

  18. Working session 1: Tubing degradation

    Energy Technology Data Exchange (ETDEWEB)

    Kharshafdjian, G. [Atomic Energy of Canada, Mississauga, Ontario (Canada); Turluer, G. [IPSN, Fontenay-aux-Roses (France)

    1997-02-01

    A general introductory overview of the purpose of the group and the general subject area of SG tubing degradation was given by the facilitator. The purpose of the session was described as to {open_quotes}develop conclusions and proposals on regulatory and technical needs required to deal with the issues of SG tubing degradation.{close_quotes} Types, locations and characteristics of tubing degradation in steam generators were briefly reviewed. The well-known synergistic effects of materials, environment, and stress and strain/strain rate, subsequently referred to by the acronym {open_quotes}MESS{close_quotes} by some of the group members, were noted. The element of time (i.e., evolution of these variables with time) was emphasized. It was also suggested that the group might want to consider the related topics of inspection capabilities, operational variables, degradation remedies, and validity of test data, and some background information in these areas was provided. The presentation given by Peter Millet during the Plenary Session was reviewed; Specifically, the chemical aspects and the degradation from the secondary side of the steam generator were noted. The main issues discussed during the October 1995 EPRI meeting on secondary side corrosion were reported, and a listing of the potential SG tube degradations was provided and discussed.

  19. Characterisation of Chemical Degradation of Polymers

    DEFF Research Database (Denmark)

    Kjellander, Carina Koch

    2008-01-01

    Arbejdet har fokuseret på kemisk især hydrolytisk nedbrydning af industrielt vigtige polymerer eksponeret i forskellige aggressive men industrielt realistiske miljøer. Hovedvægten har ligget på eksponeringer af uforstærket polyamid 66 i 10% vandig NaOH ved 60 oC og i 5% NaOCl ved 20 oC i variende...

  20. Microbial PAH-Degradation in Soil: Degradation Pathways and Contributing Factors

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xu-Xiang; CHENG Shu-Pei; ZHU Cheng-Jun; SUN Shi-Lei

    2006-01-01

    Adverse effects on the environment and high persistence in the microbial degradation and environmental fate of polycyclic aromatic hydrocarbons (PAHs) are motivating interest. Many soil microorganisms can degrade PAHs and use various metabolic pathways to do so. However, both the physio-chemical characteristics of compounds as well as the physical, chemical, and biological properties of soils can drastically influence the degradation capacity of naturally occurring microorganisms for field bioremediation. Modern biological techniques have been widely used to promote the efficiency of microbial PAH-degradation and make the biodegradation metabolic pathways more clear. In this review microbial degradation of PAHs in soil is discussed, with emphasis placed on the main degradation pathways and the environmental factors affecting biodegradation.

  1. Radiation degradation of cellulose

    International Nuclear Information System (INIS)

    The application of straw and other cellulose polymers as feedstuff for ruminants is limited by its low digestibility. During recent decades it was attempted to increase the digestibility of straw by several chemical and physical methods. In this work some results of the degradation of gamma and electron treated wheat straw are reported. Complex methods of treatment (e.g. radiation influence and influence of lyes) are taken into consideration. In vitro-experiments with radiation treated straw show that the digestibility can be increased from 20% up to about 80%. A high pressure liquid chromatography method was used to analyze the hydrolysates. The contents of certain species of carbohydrates in the hydrolysates in dependence on the applied dose are given

  2. Efeito de leguminosas nas características químicas e matéria orgânica de um solo degradado Effect of leguminous crops on the chemical characteristics and organic matter of a degraded soil

    Directory of Open Access Journals (Sweden)

    João T. Nascimento

    2003-12-01

    Full Text Available Com a finalidade de avaliar o efeito de leguminosas nas características químicas de um Luvissolo degradado instalou-se, no município de Alagoinha, PB, um experimento, de 1997-99, com doze espécies: crotalária (Crotalaria juncea, L, guandu (Cajanus cajan,L, guandu-anão (Cajanus cajan (L Millsp, calopogônio (Calopogonium mucunoides, L, feijão-de-porco (Canavalia ensiforme, L, lab-lab (Dolichos lab lab, L, kudzu tropical (Pueraria phaseoloides, L, siratro (Macroptilium atropurpureum, L, leucena (Leucaena leucocephala, L, cunhã (Clitoria ternatea, L, mucuna preta (Styzolobium aterrimum, L e mucuna cinza (Styzolobium cinereum Piper e Tracy além do tratamento testemunha. Nesse estudo, o solo do experimento não recebeu adubo mineral nem corretivo. Avaliaram-se as características químicas do solo, nas profundidades 0-10, 10-20 e 20-30 cm. Os resultados mostraram efeitos significativos das leguminosas sobre a fertilidade do solo, em comparação com a testemunha, com incrementos significativos de pH e de cátions trocáveis, refletindo positivamente na CTC e no índice de saturação por bases. Na matéria orgânica não ocorreu efeito significativo entre leguminosas e testemunha.With the purpose of evaluating the effect of leguminous crops on the chemical characteristics of a degraded Alfisol, in the municipal district of Alagoinha, PB, Brazil, an experiment was conducted during 1997-99 with twelve species: Crotalaria juncea L, Cajanus cajan L, Cajanus cajan (L Millsp, Calopogonium mucunoides L, Canavalia ensiformis L, Dolichos lab lab L, Pueraria phaseoloides L, Macroptilium atropurpureum L, Leucaena leucocephala L, Clitoria ternatea L, Styzolobium aterrimum L, and Styzolobium cinereum Piper and Tracy besides a control treatment. In this study, the soil of the experimental site did not receive mineral fertilizer nor any corrective. The chemical characteristics of the soil were evaluated at 0-10, 10-20 and 20-30 cm depths. The results

  3. Fate of products of degradation processes: consequences for climatic change

    NARCIS (Netherlands)

    Slanina, J.; Brink, ten H.M.; Khlystov, A.

    1999-01-01

    The end products of atmospheric degradation are not only CO2 and H2O but also sulfate and nitrate depending on the chemical composition of the substances which are subject to degradation processes. Atmospheric degradation has thus a direct influence on the radiative balance of the earth not only due

  4. Lactose contaminant as steroid degradation enhancer

    NARCIS (Netherlands)

    Nieuwmeyer, Florentine; Maarschalk, Kees van der Voort; Vromans, Herman

    2008-01-01

    Purpose. By pharmaceutical processes and in the presence of solid excipients physical-chemical changes are known to occur, leading to increased rate of chemical degradation. The purpose of this work was to determine the critical aspects in the stability of a steroid in the presence of a commonly use

  5. Biodegradability of degradable plastic waste.

    Science.gov (United States)

    Agamuthu, P; Faizura, Putri Nadzrul

    2005-04-01

    Plastic waste constitutes the third largest waste volume in Malaysian municipal solid waste (MSW), next to putrescible waste and paper. The plastic component in MSW from Kuala Lumpur averages 24% (by weight), whereas the national mean is about 15%. The 144 waste dumps in the country receive about 95% of the MSW, including plastic waste. The useful life of the landfills is fast diminishing as the plastic waste stays un-degraded for more than 50 years. In this study the compostability of polyethylene and pro-oxidant additive-based environmentally degradable plastics (EDP) was investigated. Linear low-density polyethylene (LLDPE) samples exposed hydrolytically or oxidatively at 60 degrees C showed that the abiotic degradation path was oxidative rather than hydrolytic. There was a weight loss of 8% and the plastic has been oxidized as shown by the additional carbonyl group exhibited in the Fourier transform infra red (FTIR) Spectrum. Oxidation rate seemed to be influenced by the amount of pro-oxidant additive, the chemical structure and morphology of the plastic samples, and the surface area. Composting studies during a 45-day experiment showed that the percentage elongation (reduction) was 20% for McD samples [high-density polyethylene, (HDPE) with 3% additive] and LL samples (LLDPE with 7% additive) and 18% reduction for totally degradable plastic (TDP) samples (HDPE with 3% additive). Lastly, microbial experiments using Pseudomonas aeroginosa on carbon-free media with degradable plastic samples as the sole carbon source, showed confirmatory results. A positive bacterial growth and a weight loss of 2.2% for degraded polyethylene samples were evident to show that the degradable plastic is biodegradable.

  6. Efecto del ensilado sobre la composición química y degradabilidad ruminal de la pomasa de manzana Effect of ensiling on chemical composition and rumen degradability of apple pomace

    Directory of Open Access Journals (Sweden)

    RENE ANRIQUE G.

    2002-01-01

    Full Text Available Se evaluó el efecto del ensilado en la dinámica de degradación de la materia seca (MS y composición química de pomasa de manzana fresca y ensilada. La degradabilidad ruminal se determinó por fermentación in situ, empleando bolsas de nylon, a tiempos de fermentación de 2, 6, 12, 24 y 36 horas, con seis repeticiones por horario y por tipo de pomasa. El ensilado produjo un aumento del contenido relativo de MS, proteína cruda (PC, fibra cruda (FC y fibra detergente ácido (FDA (43.7, 13.0, 14.3 y 18.4% respectivamente y una reducción del contenido de energía metabolizable (4.9%. La degradabilidad de la materia seca fue mayor en pomasa fresca que ensilada (pevaluated. Rumen degradability was determined in situ by the nylon bag technique at 2, 6, 12, 24 and 36 hrs fermentation with 6 replicates per time and apple pomace type. Ensiling increased the relative contents of DM, crude protein (CP, crude fiber (CF and acid detergent fiber (ADF (43.7, 13.0, 14.3 and 18.4% respectively and reduced the metabolizable energy content (4.9%. Degradability was greater in fresh compared to ensiled apple pomace (p<0.05, however, the advantage decreased from 26% at 2 hrs to 3.3% at 36 hrs fermentation (84.9 vs 82.2 %, 93-95% of the potential degradability was obtained at 36 hrs fermentation. Values for soluble, slowly degradable and undegradable fractions of fresh and ensiled pomace, respectively were: 26.5 and 13.8%; 62.3 and 75.7%; 11.2 and 10.5%; potential degradability and degradation rates were: 88.8 and 89.5%; 0.076 and 0.065 hr-1, respectively. In ensiled pomace the insoluble fraction contributed more to DM degraded at 36 hrs (73.4 vs 92.1% suggesting a greater fiber degradability and a more uniform degradation pattern with time. Due to its higher fiber and insoluble fraction content, effective degradability was lower in ensiled apple pomace

  7. Degradación física y química de un Haplustol típico bajo distintos sistemas de manejo de suelo Physical and chemical degradation of a typic Haplustoll under different management systems

    Directory of Open Access Journals (Sweden)

    Gerardo Agustín Sanzano

    2005-07-01

    que en LC. De todos modos, la infiltración del suelo virgen de MN fue significativamente mayor que en las otras tres situaciones Un comportamiento similar tuvieron los suelos con respecto a la conductividad hidráulica. La macroporosidad no difirió entre tratamientos, pero también fue significativamente más alta en el monte natural virgen. La falta de recuperación de estos tres parámetros con respecto al monte natural indica el bajo nivel de recuperación de los suelos estudiados. Sin embargo, debido a la naturaleza seca subhúmeda y semiárida de la región, las diferencias en la infiltración entre los sistemas conservacionistas y convencionales producen un aumento en el almacenaje de agua, que es una variable vital para el desarrollo adecuado de los cultivos.In the province of Tucumán there was a great process of expansion of the farming borders to dry sub humid and semi-arid areas. This process led to the physical, chemical and biological degradation of the soils. The objective of this work was to determine the long term effects of different tillage systems on physical and chemical degradation of a Typic Haplustoll and its relationship with hydraulic properties related to water storage. In a tillage experiment established 20 years ago soybean under no till and conventional tillage, gramineous pastures (P and natural forest (MN, the following properties were studied: organic carbon (CO, extractable phosphorous (Pe, cationic exchange capacity (CIC, pH, bulk density (DA, structural stability (EE, hydraulic conductivity (Ksat, basic infiltration (Ibas and pores greater than 0,25 mm. There were significative differences in CO and CIC between LC and treatments P and SD, but also between P and SD with MN. Pe contents were 28, 16 and 14 % for SD, P and LC respectively in relation to MN. Soil pH was not affected by the different tillage systems. The structural stability was the property that appeared to be more sensitive to the soil tillage in a decreasing sequence

  8. PEM fuel cell degradation

    Energy Technology Data Exchange (ETDEWEB)

    Borup, Rodney L [Los Alamos National Laboratory; Mukundan, Rangachary [Los Alamos National Laboratory

    2010-01-01

    The durability of PEM fuel cells is a major barrier to the commercialization of these systems for stationary and transportation power applications. While significant progress has been made in understanding degradation mechanisms and improving materials, further improvements in durability are required to meet commercialization targets. Catalyst and electrode durability remains a primary degradation mode, with much work reported on understanding how the catalyst and electrode structure degrades. Accelerated Stress Tests (ASTs) are used to rapidly evaluate component degradation, however the results are sometimes easy, and other times difficult to correlate. Tests that were developed to accelerate degradation of single components are shown to also affect other component's degradation modes. Non-ideal examples of this include ASTs examining catalyst degradation performances losses due to catalyst degradation do not always well correlate with catalyst surface area and also lead to losses in mass transport.

  9. Advanced Oxidation Degradation of Diclofenac

    International Nuclear Information System (INIS)

    Advanced oxidation/reduction processes (AO/RPs), utilize free radical reactions to directly degrade chemical contaminants as an alternative to traditional water treatment. This study reports the absolute rate constants for reaction of diclofenac sodium and the model compound (2, 6-dichloraniline) with the two major AO/RP radicals; the hydroxyl radical (•OH) and hydrated electron (e-aq). The bimolecular reaction rate constants (M-1 s-1) for diclofenac for •OH was (9.29 ± 0.11) x 109, and, for e- aq was (1.53 ± 0.03) x109. Preliminary degradation mechanisms are suggested based on product analysis using 60Co γ-irradiation and LC-MS for reaction by-product identification. The toxicity of products was evaluated using the Vibrio fischeri luminescent bacteria method. (author)

  10. Aflatoxin B₁ degradation by a Pseudomonas strain.

    Science.gov (United States)

    Sangare, Lancine; Zhao, Yueju; Folly, Yawa Minnie Elodie; Chang, Jinghua; Li, Jinhan; Selvaraj, Jonathan Nimal; Xing, Fuguo; Zhou, Lu; Wang, Yan; Liu, Yang

    2014-10-23

    Aflatoxin B1 (AFB1), one of the most potent naturally occurring mutagens and carcinogens, causes significant threats to the food industry and animal production. In this study, 25 bacteria isolates were collected from grain kernels and soils displaying AFB1 reduction activity. Based on its degradation effectiveness, isolate N17-1 was selected for further characterization and identified as Pseudomonas aeruginosa. P. aeruginosa N17-1 could degrade AFB₁, AFB₂ and AFM₁ by 82.8%, 46.8% and 31.9% after incubation in Nutrient Broth (NB) medium at 37 °C for 72 h, respectively. The culture supernatant of isolate N17-1 degraded AFB₁ effectively, whereas the viable cells and intra cell extracts were far less effective. Factors influencing AFB1 degradation by the culture supernatant were investigated. Maximum degradation was observed at 55 °C. Ions Mn²⁺ and Cu²⁺ were activators for AFB1 degradation, however, ions Mg²⁺, Li⁺, Zn²⁺, Se²⁺, Fe³⁺ were strong inhibitors. Treatments with proteinase K and proteinase K plus SDS significantly reduced the degradation activity of the culture supernatant. No degradation products were observed based on preliminary LC-QTOF/MS analysis, indicating AFB₁ was metabolized to degradation products with chemical properties different from that of AFB₁. The results indicated that the degradation of AFB₁ by P. aeruginosa N17-1 was enzymatic and could have a great potential in industrial applications. This is the first report indicating that the isolate of P. aeruginosa possesses the ability to degrade aflatoxin.

  11. Degradation of polychlorinated biphenyls

    International Nuclear Information System (INIS)

    Polychlorinated biphenyls (PCB) are generally disposed of by incineration, an expensive and hazardous method. Moreover, in cases where the PCBs are a minor component of a nontoxic fluid, such as a dielectric fluid, incineration causes loss of the nontoxic fluid as well as the PCB. An alternative method for destroying PCBs is disclosed which is not only capable of detoxification of PCB-contaminated soils, sludges, and sediments, but can also remove PCBs from solution in a wide range of concentrations, permitting full recovery of the bulk of the solution free of PCBs. The process of the invention may be operated in a batch, continuous, or semicontinuous mode, and is advantageously used to detoxify organic liquids such as transformer oils. According to the invention, PCBs are chemically degraded by contact with a Lewis acid catalyst in a nonaqueous liquid medium, in the presence of a cation which combines with the chlorine on the PCB to form a solid chloride of the cation which will precipitate out from the liquid medium. Preferred Lewis acids are metal halides, particularly a combination of aluminum chloride and ferric chloride, and the preferred cation is potassium in the form of KOH. The Lewis acids may be supplied to the process by the adventitious corrosion of a vessel containing the PCB-contaminated matter. Experiments are described to illustrate the process of the invention. 3 figs

  12. Insulation-resistance degradation kinetics of bulk BaTi1-ξAξO3-Δ and defect-chemical origin of acceptor-type(A) and doping-level(ξ) effect

    Science.gov (United States)

    Kwon, Hyung-Soon; Yoon, Seok-Hyun; Yoo, Han-Ill

    2016-07-01

    Dearth of the reproducible, consistent observations on insulation-resistance (IR) degradation kinetics of bulk dielectric BaTiO3 may be attributed to their conventional measurement method, two-probe potentiostatic, which would be by no means free from the electrode effect for a finite- dimension specimen in particular. We hereby measured the IR-degradation kinetics galvanostatically by using a series of inner probes on bulk BaTi1-ξAξO3-Δ (A = Al, Mn; ξ = 0.001, 0.003, 0.010) with their high-temperature (1000 °C) equilibrium ionic-defect-structure in air being frozen-in at 250 °C and compared with the kinetics as calculated on the basis of the electromigration of frozen-in oxygen vacancies ( cV o ) in association with the A-ionization or hole-trapping equilibria. It has turned out that the calculated depict sufficiently precisely all the as-observed kinetics as well as the effects of acceptor type(A) and doping level(ξ), thus, quantitatively establishing the correlation between the frozen-in ionic-defect-structure and IR-degradation kinetics with new insights into the degradation inner-workings: IR-degradation is triggered as soon as the oxygen vacancy concentration at the cathode reaches that corresponding to the insulator-to-semiconductor transition ( cV S / I ) and proceeds with the front of just-turned, n-type semiconducting region ( c V = cV S / I ) moving towards the anode at a fixed velocity. The healthy lifetime of the dielectric is, thus, essentially the time duration for the cathode to achieve cV S / I from cV o , and the final stage of degradation is approximated to be the length fraction χs of the semiconductor such that χs = cV o / cV S / I . A new suggestion is finally made to further suppress the IR degradation kinetics of the bulk dielectric BaTiO3.

  13. Chemical composition and ruminal degradability of the sugar cane silage treated with chemical and bacterial additivesComposição química e degradabilidade ruminal de silagens da cana-de-açúcar tratada com aditivos químicos e bacteriano

    Directory of Open Access Journals (Sweden)

    Luiz Eduardo dos Santos

    2012-02-01

    Full Text Available The objective of this trial was to evaluate the effect of the addition of chemical and bacterial additive in the ensiling of sugar cane (Saccharum officinarum L. on chemical composition, pH, kinectic fraction and in situ degradation of nutritions components of silages. Five rumen-cannulated ½ Simental + ½ Zebu steers were allotted to a completely randomized design. The steers were placed in individual cages and they were fed with diets with 76% forage (%DM. Five silages were evaluated: control – sugar cane, no additives; urea – sugar cane + 0.5% of urea (wet basis; inoculant – sugar cane inoculated with LactoSilo® (390 g/40 t forage; NaOH – sugar cane + 1.0% of sodium hydroxide (wet basis; CaOH – sugar cane + 0.6% of calcium hydroxide (wet basis. The silage additives with sodium hydroxide showed the highest pH values before (11.20 and after (4.87 for silage. No differences were observed among the silages for dry matter (26.85, crude protein (5.25 and acid detergent fiber (57.21. Fractionation of dry matter and organic matter of silages showed similar behavior, with higher values of the soluble fraction (fraction A for silages with sodium hydroxide (45.86 and 30.95% and calcium hydroxide (29.47 and 26.13%. The use of sodium hydroxide allowed obtaining higher values for the degradation of cell wall components of silages from cane sugar. The potencial and effective degradability with 3, 5 and 8%/h of passage rate were respectively 88.44, 64.45, 56.73 and 49.83% for NDF and 82.57, 55.51, 46.72 and 38.83% for ADF, indicating that the use of sodium hydroxide as chemical additives can improve the nutritive value of cane sugar silage.Objetivou-se avaliar o efeito da inclusão de aditivos químicos e bacterianos na ensilagem de cana-de-açúcar sobre a composição, pH, fracionamento e cinética de degradação in situ dos componentes nutritivos. Utilizaram-se cinco bovinos ½ Simental + ½ Zebu providos de cânula ruminal, alocados em

  14. Mechanisms of humic substances degradation by fungi

    Science.gov (United States)

    Chen, Y.; Hadar, Y.; Grinhut, T.

    2012-04-01

    Humic substances (HS) are formed by secondary synthesis reactions (humification) during the decay process and transformation of biomolecules originating from plants and other dead organisms. In nature, HS are extremely resistant to biological degradation. Thus, these substances are major components in the C cycle and in the biosphere and therefore, the understanding of the process leading to their formation and transformation and degradation is vital. Fungi active in the decomposition process of HS include mainly ascomycetes and basidiomycetes that are common in the upper layer of forest and grassland soils. Many basidiomycetes belong to the white-rot fungi (WRF) and litter-decomposing fungi (LDF). These fungi are considered to be the most efficient lignin degraders due to their nonspecific oxidizing enzymes: manganese peroxidase (MnP), lignin peroxidase (LiP) and laccase. Although bacteria dominate compost and participate in the turnover of HS, their ability to degrade stable macromolecules such as lignin and HS is limited. The overall objectives of this research were to corroborate biodegradation processes of HS by WRF. The specific objectives were: (i) To isolate, identify and characterize HS degrading WRF from biosolids (BS) compost; (ii) To study the biodegradation process of three types of HS, which differ in their structure, by WRF isolated from BS compost; and (iii) To investigate the mechanisms of HA degradation by WRF using two main approaches: (a) Study the physical and chemical analyses of the organic compounds obtained from direct fungal degradation of HA as well as elucidation of the relevant enzymatic reactions; and (b) Study the enzymatic and biochemical mechanisms involved during HA degradation. In order to study the capability of fungi to degrade HS, seventy fungal strains were isolated from biosolids (BS) compost. Two of the most active fungal species were identified based on rDNA sequences and designated Trametes sp. M23 and Phanerochaetesp., Y6

  15. Prediction of drug degradants using DELPHI: an expert system for focusing knowledge.

    Science.gov (United States)

    Pole, David L; Ando, Howard Y; Murphy, Sean T

    2007-01-01

    DELPHI is an expert system that has been developed to predict possible degradants of pharmaceutical compounds under stress testing conditions. It has been programmed with the objective of finding relevant degradation pathways, identifying degradant structures, and providing tools to the analytical chemist to assist in degradation identification. The system makes degradant predictions based on the chemical structure of the drug molecule and precedent from a broad survey of the literature. A description of DELPHI's treatment of molecular perception is described as are many features of the heuristic degradation rules it uses to capture and apply chemical degradation knowledge. DELPHI's utility for capturing institutional knowledge is discussed in relation to an analysis of degradation prediction results for 250 molecules of diverse chemical structure collected over 5 years of use. As such, it provides a reliable, convenient, and rapid tool for evaluating potential pathways of chemical instability of pharmaceuticals. PMID:17602568

  16. Degradation of sulfur dioxide using plasma technology

    International Nuclear Information System (INIS)

    This paper presents the electro-chemical study performed for sulfur dioxide (SO2) treatment using non thermal plasma coupled to a nano structured fluid bed enhancing the toxic gas removal and the adsorption of acids formed during plasma treatment, more of 80% of removal was obtained. Non thermal plasma was ignited by dielectric barrier discharge (Dbd). The research was developed through an analysis of the chemical kinetics of the process and experimental study of degradation; in each experiment the electrical parameters and the influence of carbon nano structures were monitored to establish the optimal conditions of degradation. We compared the theoretical and experimental results to conclude whether the proposed model is correct for degradation. (Author)

  17. Degradation Mechanisms in Oxygen Ion Conducting Materials

    Science.gov (United States)

    Lussier, Alexandre; Finsterbusch, Martin; Idzerda, Yves U.

    2010-03-01

    We have developed a testing apparatus to characterize degradation mechanisms in oxygen ion conducting materials, with an emphasis on Solid Oxide Fuel Cell (SOFC) materials. While chemical potentials drive currents in SOFCs, we utilize a simple electrical potential to drive oxygen ionic currents through materials and interfaces. We can additionally adjust the temperature and gaseous environment of our experiment, enabling us to identify and characterize degradation mechanisms and their causes. Early performance results confirm multiple SOFC cathode degradation mechanisms driven by both high temperatures and ion currents. In particular, cation inter-diffusion is prevalent at interfaces such as those between La(0.6)Sr(0.4)Co(0.2)Fe(0.8)O(3) and Ga-doped CeO(2) resulting in an interfacial structure which is increasingly resistant to subsequent oxygen ion flow. By isolating and understanding various degradation mechanisms we can more effectively address those mechanisms to improve long term ion conducting material performance.

  18. Bacterial degradation of monocyclic aromatic amines

    Directory of Open Access Journals (Sweden)

    Pankaj Kumar Arora

    2015-08-01

    Full Text Available Aromatic amines are an important group of industrial chemicals, which are widely used for manufacturing of dyes, pesticides, drugs, pigments, and other industrial products. These compounds have been considered highly toxic to human beings due to their carcinogenic nature. Three groups of aromatic amines have been recognized: monocyclic, polycyclic and heterocyclic aromatic amines. Bacterial degradation of several monocyclic aromatic compounds has been studied in a variety of bacteria, which utilizes monocyclic aromatic amines as their sole source of carbon and energy. Several degradation pathways have been proposed and the related enzymes and genes have also been characterized. Many reviews have been reviewed toxicity of monocyclic aromatic amines; however, there is lack of review on biodegradation of monocyclic aromatic amines. The aim of this review is to summarize bacterial degradation of monocyclic aromatic amines. This review will increase our current understanding of biochemical and molecular basis of bacterial degradation of monocyclic aromatic amines.

  19. Analysis of thermally-degrading, confined HMX

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, M.L.; Schmitt, R.G.; Renlund, A.M.

    1996-12-01

    The response of a thermally-degrading, confined HMX pellet is analyzed using a Reactive Elastic-Plastic (REP) constitutive model which is founded on the collapse and growth of internal inclusions resulting from physical and chemical processes such as forced displacement, thermal expansion, and/or decomposition. Axial stress predictions compare adequately to data. Deficiencies in the model and future directions are discussed.

  20. INTERMITTENT DEGRADATION AND SCHIZOTYPY

    OpenAIRE

    Roché, Matthew W.; Silverstein, Steven M.; Lenzenweger, Mark F.

    2015-01-01

    Intermittent degradation refers to transient detrimental disruptions in task performance. This phenomenon has been repeatedly observed in the performance data of patients with schizophrenia. Whether intermittent degradation is a feature of the liability for schizophrenia (i.e., schizotypy) is an open question. Further, the specificity of intermittent degradation to schizotypy has yet to be investigated. To address these questions, 92 undergraduate participants completed a battery of self-repo...

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

    International Nuclear Information System (INIS)

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

  2. Teardown analysis for detecting shelf-life degradation

    Science.gov (United States)

    Eckstein, A. S.

    1971-01-01

    Analysis is guideline in examining component materials, analytically determining physical properties and chemical compositions, and developing control data necessary for ascertaining effects of environments and their influence on deterioration and degradation mechanisms.

  3. Oven-drying reduces ruminal starch degradation in maize kernels

    NARCIS (Netherlands)

    Ali, M.; Cone, J.W.; Hendriks, W.H.; Struik, P.C.

    2014-01-01

    The degradation of starch largely determines the feeding value of maize (Zea mays L.) for dairy cows. Normally, maize kernels are dried and ground before chemical analysis and determining degradation characteristics, whereas cows eat and digest fresh material. Drying the moist maize kernels (consist

  4. Qualitative aspects of the degradation of mitomycins in alkaline solution.

    Science.gov (United States)

    Beijnen, J H; den Hartigh, J; Underberg, W J

    1985-01-01

    The major degradation product in alkaline solution of mitomycin A, mitomycin C and porfiromycin is the corresponding 7-hydroxymitosane. The isolation and the physico-chemical and analytical properties of these compounds and their derivatized analogues are discussed. Data are presented on the degradation of mitomycin C at extremely high pH values. PMID:16867711

  5. Rate of NDF degradation

    DEFF Research Database (Denmark)

    Weisbjerg, Martin Riis; Koukolová, V; Lund, Peter

    2007-01-01

    Degradation profiles for NDF were estimated for 83 samples of grass/grass-clover, 27 samples of cereal whole crop and 14 samples of maize whole crop.......Degradation profiles for NDF were estimated for 83 samples of grass/grass-clover, 27 samples of cereal whole crop and 14 samples of maize whole crop....

  6. Anaerobic microbial degradation of organochlorine insecticides Aldrin

    Energy Technology Data Exchange (ETDEWEB)

    Chiu, T.C.; Yen, J.H.; Wang, Y.S. [National Taiwan Univ. (Taiwan)

    2004-09-15

    Aldrin (1,2,3,4,10,10-hexachloro-1,4,4a,5,8,8a-hexahydro-1,4-endo-exo-5,8-dimethanonnaphthalene), a cyclodiene organochlorine insecticide, was banned by nations and classified as B2 carcinogen by United States Environmental Protection Agency (EPA). Because of its chemical stability and lipophilicity, aldrin is regarded as a persistent and recalcitrant compound. Aldrin is easily adsorbed to soil and sediment after spreading to the environments, furthermore, it may be accumulated in animal's tissue or milk and then cause adverse effects by food-chain. The dissipation process of aldrin in environments has continuously been paid much attention by researchers. In general, the dissipation of aldrin has been thought as relating to three mechanisms: photo-degradation, chemical hydrolysis, and microbial degradation. And it has been well known that microbial degradation is the most important agent for breakdown of organochlorine pesticides. There has been shown that aldrin could be transformed to its metabolites, such as dieldrin or photo-dieldrin, by microorganisms under aerobic conditions, however, limited information has been shown under anaerobic conditions. For this reason, the degradation potential of aldrin by anaerobic microorganisms obtained from indigenous river sediment was evaluated, and the effect of environmental factors such as temperatures and nutrients on the aldrin degradation was also investigated in this study.

  7. Microbial Degradation of Aniline by Bacterial Consortium

    Institute of Scientific and Technical Information of China (English)

    JIAN-LONG WANG; ZE-YU MAO; WEI-ZHONG WU

    2003-01-01

    Objective To investigate the characteristics of microbial degradation of aniline by a stable bacterial consortium. Methods The bacterial consortium was isolated from activated sludge treating chemical wastewater using aniline as the sole source of carbon and nitrogen by enrichment and isolation technique. The biomass was measured as optical density (OD) at 510 nm using a spectrophotometer. Aniline concentrations were determined by spectrophotometer. The intermediates of aniline degradation were identified by GC/MS method. Results The bacterial consortium could grow at a range of aniline concentrations between 50 and 500 mg/L. The optimal pH and temperature for aniline degradation were determined to be 7.0 and 30, respectively. The presence of NH4NO3 as an additional nitrogen source (100-500 mg/L) had no adverse effect on bacterial growth and aniline degradation. The presence of heavy metal ions, such as Co2+, Zn2+, Ni2+, Mn2+ and Cu2+ had an inhibitory effect on aniline degradation. Conclusions The isolated bacterial consortium candegrade aniline up to 500 mg/L effectively and tolerate some heavy metal ions that commonly exist in chemical wastewater. It has a potential to be applied in the practical treatment of aniline-containingwastewater.

  8. Silk structure and degradation.

    Science.gov (United States)

    Liu, Bin; Song, Yu-wei; Jin, Li; Wang, Zhi-jian; Pu, De-yong; Lin, Shao-qiang; Zhou, Chan; You, Hua-jian; Ma, Yan; Li, Jin-min; Yang, Li; Sung, K L Paul; Zhang, Yao-guang

    2015-07-01

    To investigate the structure of silk and its degradation properties, we have monitored the structure of silk using scanning electron microscopy and frozen sections. Raw silk and degummed raw silk were immersed in four types of degradation solutions for 156 d to observe their degradation properties. The subcutaneous implants in rats were removed after 7, 14, 56, 84, 129, and 145 d for frozen sectioning and subsequent staining with hematoxylin and eosin (H.E.), DAPI, Beta-actin and Collagen I immunofluorescence staining. The in vitro weight loss ratio of raw silk and degummed raw silk in water, PBS, DMEM and DMEM containing 10% FBS (F-DMEM) were, respectively, 14%/11%, 12.5%/12.9%, 11.1%/14.3%, 8.8%/11.6%. Silk began to degrade after 7 d subcutaneous implantation and after 145 d non-degraded silk was still observed. These findings suggest the immunogenicity of fibroin and sericin had no essential difference. In the process of in vitro degradation of silk, the role of the enzyme is not significant. The in vivo degradation of silk is related to phagocytotic activity and fibroblasts may be involved in this process to secrete collagen. This study also shows the developing process of cocoons and raw silk. PMID:25982316

  9. Q degradations in superconducting niobium cavities

    International Nuclear Information System (INIS)

    In the past year, several laboratories around the world have observed degradations of the Q value of superconducting niobium cavities made from high thermal conductivity niobium under certain cooldown conditions. Especially under slow cooldown or warmup to temperatures < 200 K of larger systems severe degradations have been reported. A systematic study of the influence of the cooldown speed, warmup conditions, multiple cooldowns and chemical surface treatment on cavity performance of cavities manufactured from niobium of different purity has been conducted. Possible cures such as anodic oxidation are being explored and results of these investigations are reported

  10. Structural elucidation of gemifloxacin mesylate degradation product.

    Science.gov (United States)

    Paim, Clésio Soldateli; Führ, Fernanda; Martins, Magda Targa; Gnoatto, Simone; Bajerski, Lisiane; Garcia, Cássia Virginia; Steppe, Martin; Schapoval, Elfrides Eva Scherman

    2016-03-01

    Gemifloxacin mesylate (GFM), chemically (R,S)-7-[(4Z)-3-(aminomethyl)-4-(methoxyimino)-1-pyrrolidinyl]-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid methanesulfonate, is a synthetic broad-spectrum antibacterial agent. Although many papers have been published in the literature describing the stability of fluorquinolones, little is known about the degradation products of GFM. Forced degradation studies of GFM were performed using radiation (UV-A), acid (1 mol L(-1) HCl) and alkaline conditions (0.2 mol L(-1) NaOH). The main degradation product, formed under alkaline conditions, was isolated using semi-preparative LC and structurally elucidated by nuclear magnetic resonance (proton - (1) H; carbon - (13) C; correlate spectroscopy - COSY; heteronuclear single quantum coherence - HSQC; heteronuclear multiple-bond correlation - HMBC; spectroscopy - infrared, atomic emission and mass spectrometry techniques). The degradation product isolated was characterized as sodium 7-amino-1-pyrrolidinyl-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylate, which was formed by loss of the 3-(aminomethyl)-4-(methoxyimino)-1-pyrrolidinyl ring and formation of the sodium carboxylate. The structural characterization of the degradation product was very important to understand the degradation mechanism of the GFM under alkaline conditions. In addition, the results highlight the importance of appropriate protection against hydrolysis and UV radiation during the drug-development process, storage, handling and quality control.

  11. SPECIFIC DEGRADATION OF WATERSHEDS

    Institute of Scientific and Technical Information of China (English)

    Boubacar KANE; Pierre Y.JULIEN

    2007-01-01

    An extensive database of reservoir sedimentation surveys throughout continental United States is compiled and analyzed to determine specific degradation SD relationships as function of mean annual rainfall R, drainage area A, and watershed slope S. The database contains 1463 field measurements and specific degradation relationships are defined as function of A, R and S. Weak trends and significant variability in the data are noticeable. Specific degradation measurements are log normally distributed with respect to R, A, and S and 95% confidence intervals are determined accordingly. The accuracy of the predictions does not significantly increase as more independent variables are added to the regression analyses.

  12. Protein and Lipid Binding Parameters in Rainbow Trout (Oncorhynchus mykiss) Blood and Liver Fractions to Extrapolate from an in Vitro metabolic Degradation Assay to in Vivo Bioaccumulation Potential of Hydrophobic Organic Chemicals

    Science.gov (United States)

    Biotransformation reduces the extent to which environmental contaminants accumulate in fish and other aquatic biota. Unfortunately, the tendency for compounds to be metabolized is not easily predicted from physico-chemical properties (e.g., octanol:water partitioning) or an exam...

  13. North American Soil Degradation: Processes, Practices, and Mitigating Strategies

    Directory of Open Access Journals (Sweden)

    R. L. Baumhardt

    2015-03-01

    Full Text Available Soil can be degraded by several natural or human-mediated processes, including wind, water, or tillage erosion, and formation of undesirable physical, chemical, or biological properties due to industrialization or use of inappropriate farming practices. Soil degradation occurs whenever these processes supersede natural soil regeneration and, generally, reflects unsustainable resource management that is global in scope and compromises world food security. In North America, soil degradation preceded the catastrophic wind erosion associated with the dust bowl during the 1930s, but that event provided the impetus to improve management of soils degraded by both wind and water erosion. Chemical degradation due to site specific industrial processing and mine spoil contamination began to be addressed during the latter half of the 20th century primarily through point-source water quality concerns, but soil chemical degradation and contamination of surface and subsurface water due to on-farm non-point pesticide and nutrient management practices generally remains unresolved. Remediation or prevention of soil degradation requires integrated management solutions that, for agricultural soils, include using cover crops or crop residue management to reduce raindrop impact, maintain higher infiltration rates, increase soil water storage, and ultimately increase crop production. By increasing plant biomass, and potentially soil organic carbon (SOC concentrations, soil degradation can be mitigated by stabilizing soil aggregates, improving soil structure, enhancing air and water exchange, increasing nutrient cycling, and promoting greater soil biological activity.

  14. Conceptualizing Forest Degradation.

    Science.gov (United States)

    Ghazoul, Jaboury; Burivalova, Zuzana; Garcia-Ulloa, John; King, Lisa A

    2015-10-01

    Forest degradation is a global environmental issue, but its definition is problematic. Difficulties include choosing appropriate reference states, timescales, thresholds, and forest values. We dispense with many such ambiguities by interpreting forest degradation through the frame of ecological resilience, and with reference to forest dynamics. Specifically, we define forest degradation as a state of anthropogenically induced arrested succession, where ecological processes that underlie forest dynamics are diminished or severely constrained. Metrics of degradation might include those that reflect ecological processes shaping community dynamics, notably the regeneration of plant species. Arrested succession implies that management intervention is necessary to recover successional trajectories. Such a definition can be applied to any forest ecosystem, and can also be extended to other ecosystems. PMID:26411619

  15. Bacterial Degradation of Pesticides

    DEFF Research Database (Denmark)

    Knudsen, Berith Elkær

    . Bioaugmentation i.e. addition of specific degrader organisms, has been suggested as an environmentally friendly and economically competitive strategy for cleaning polluted sites. Several organisms have been isolated, capable of degrading different compounds. However the capacity to degrade the desired compound...... could potentially improve bioremediation of BAM. An important prerequisite for bioaugmentation is the potential to produce the degrader strain at large quantities within reasonable time. The aim of manuscript II, was to optimize the growth medium for Aminobacter MSH1 and to elucidate optimal growth...... analysis revealed that D47 had an inhibitory effect on the fungal growth; however the effect on LEJ702 was lessened in presence of SRS16. This effect of SRS16 was not seen on LEJ703. These results stress the importance of testing the consortia, as it is impossible to predict the outcome of the created...

  16. [Degradation of succinylcholine chloride].

    Science.gov (United States)

    Németh, G; Török, I; Paál, T

    1993-05-01

    Quantitative thin-layer chormatographic method has been developed for the investigation of the degradation of injection formulations containing succinylcholinium chloride. The method is based on the denistometric determination of the main degradation product, choline at 430 nm after visualization with iodine vapour. The stability of the injection was investigated under various storage conditions and it has been stated that considerable decomposition takes place during as short a period as one week. PMID:8362654

  17. Bacteria and lignin degradation

    Institute of Scientific and Technical Information of China (English)

    Jing LI; Hongli YUAN; Jinshui YANG

    2009-01-01

    Lignin is both the most abundant aromatic (phenolic) polymer and the second most abundant raw material.It is degraded and modified by bacteria in the natural world,and bacteria seem to play a leading role in decomposing lignin in aquatic ecosystems.Lignin-degrading bacteria approach the polymer by mechanisms such as tunneling,erosion,and cavitation.With the advantages of immense environmental adaptability and biochemical versatility,bacteria deserve to be studied for their ligninolytic potential.

  18. Composição químico-bromatológica, digestibilidade e degradação in situ da dieta de ovinos em capim-tanzânia sob três frequências de desfolhação Chemical composition, digestibility and in situ degradation of sheep diet on Tanzania grass with three defoliation frequencies

    Directory of Open Access Journals (Sweden)

    Bruno Stefano Miranda Valente

    2010-01-01

    Full Text Available Objetivou-se avaliar a composição químico-bromatológica, a digestibilidade e a degradação in situ da matéria seca da dieta consumida por ovinos em pastagem de Panicum maximum cv. tanzânia sob três frequências de desfolhação, determinadas pela interceptação da radiação fotossinteticamente ativa (IRFA de 85, 95 e 97% no 1º e 4º dias de pastejo. O delineamento experimental foi inteiramente casualizado com arranjo fatorial 3 × 2 (três frequências de desfolhação e dois dias de pastejo, com quatro repetições (piquetes por tratamento. Para determinação da composição químico-bromatológica e da digestibilidade e ensaio de cinética de degradação da matéria seca da dieta, foi realizada uma simulação de pastejo no 1º e 4º dias de ocupação. A diminuição da frequência de desfolhação piorou a composição químico-bromatológica, a digestibilidade e a degradação do capim-tanzânia. Recomenda-se frequência de desfolhação no capim-tanzânia menor ou igual a 95% de interceptação da radiação fotossinteticamente ativa visando à manutenção da qualidade do pasto.The objective of this study was to evaluate the chemical composition, digestibility and in situ degradation of dry matter of the diet consumed by sheep grazing on Panicum maximum cv. Tanzania under three defoliation frequencies, determined by the interception of the photosynthetically active radiation in the canopy (PAR of 85, 95 and 97% on the first and fourth days of the grazing period. A randomized complete design in a 3 × 2 factorial arrangement (three defoliation frequencies and two days grazing, with four replications (poles. To determine the chemical composition, digestibility and an in situ dry matter degradation trial, a grazing simulation was carried out on the 1st and 4th days. Reduced defoliation frequency decreased the chemical composition, digestibility and in situ degradation of the diet. Thus defoliation frequency of tanzania grass is

  19. Visible-light sensitization of TiO{sub 2} photocatalysts via wet chemical N-doping for the degradation of dissolved organic compounds in wastewater treatment: a review

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wei, E-mail: Wei.Zhang@unisa.edu.au [University of Cincinnati, Environmental Engineering and Science Program, School of Energy, Environmental, Biological and Medical Engineering (United States); Jia, Baoping; Wang, Qiuze [Changzhou University, School of Materials Science and Engineering (China); Dionysiou, Dionysois [University of Cincinnati, Environmental Engineering and Science Program, School of Energy, Environmental, Biological and Medical Engineering (United States)

    2015-05-15

    Increased pollution of ground and surface water and emerging new micropollutants from a wide variety of industrial, municipal, and agricultural sources has increased demand on the development of innovative new technologies and materials whereby challenges associated with the provision of safe potable water can be addressed. Heterogeneous photocatalysis using visible-light sensitized TiO{sub 2} photocatalysts has attracted a lot of attention as it can effectively remove dissolved organic compound in water without generating harmful by-products. On this note, recent progress on visible-light sensitive TiO{sub 2} synthesis via wet chemical N-doping method is reviewed. In a typical visible-light sensitive TiO{sub 2} preparation via wet chemical methods, the chemical (e.g., N-doping content and states) and morphological properties (e.g., particle size, surface area, and crystal phase) of TiO{sub 2} in as-prepared resultants are sensitively dependent on many experimental variables during the synthesis. This has also made it very difficult to provide a universal guidance at this stage with a certainty for each variable of N-doping preparation. Instead of one-factor-at-a-time style investigation, a statistically valid parameter optimization investigation for general optima of photocatalytic activity will be certainly useful. Optimization of the preparation technique is envisaged to be beneficial to many environmental applications, i.e., dissolved organic compounds removal in wastewater treatment.

  20. Degradation of chitosan for rice crops application

    International Nuclear Information System (INIS)

    A variety of techniques including chemical and enzymatic hydrolysis, and radiation degradation processes can be used to prepare low molecular weight chitosan. Degradation of chitosan by radiation can be carried out in solid state and liquid state. Radiation degraded polysaccharides has been reported to exhibit growth-stimulating activity like phytohormones that induce the promotion in germination, shoot and root elongation in variety of plants. In this study, the chitosan was irradiated in solid state (powder form) by gamma rays within the dose range of 25-75 kGy. And the irradiated chitosan was then irradiated in solution form in the presence of hydrogen peroxide. The effects of irradiation on the molecular weight and viscosity of the chitosan were investigated using Ubbelohde Capillary Viscometer. The molecular weight and viscosity of the chitosan decreased with increment of absorbed doses. In the presence of hydrogen peroxide, the molecular weight of chitosan could be further decreased. The effect of radiation degraded chitosan on the growth promotion of rice was investigated and it was shown during seedling period of 15 days for transplanting whereby the growth is 15%-20% faster than using chemicals growth promoters. (authors)

  1. Drift Degradation Analysis

    International Nuclear Information System (INIS)

    Degradation of underground openings as a function of time is a natural and expected occurrence for any subsurface excavation. Over time, changes occur to both the stress condition and the strength of the rock mass due to several interacting factors. Once the factors contributing to degradation are characterized, the effects of drift degradation can typically be mitigated through appropriate design and maintenance of the ground support system. However, for the emplacement drifts of the geologic repository at Yucca Mountain, it is necessary to characterize drift degradation over a 10,000-year period, which is well beyond the functional period of the ground support system. This document provides an analysis of the amount of drift degradation anticipated in repository emplacement drifts for discrete events and time increments extending throughout the 10,000-year regulatory period for postclosure performance. This revision of the drift degradation analysis was developed to support the license application and fulfill specific agreement items between the U.S. Nuclear Regulatory Commission (NRC) and the U.S. Department of Energy (DOE). The earlier versions of ''Drift Degradation Analysis'' (BSC 2001 [DIRS 156304]) relied primarily on the DRKBA numerical code, which provides for a probabilistic key-block assessment based on realistic fracture patterns determined from field mapping in the Exploratory Studies Facility (ESF) at Yucca Mountain. A key block is defined as a critical block in the surrounding rock mass of an excavation, which is removable and oriented in an unsafe manner such that it is likely to move into an opening unless support is provided. However, the use of the DRKBA code to determine potential rockfall data at the repository horizon during the postclosure period has several limitations: (1) The DRKBA code cannot explicitly apply dynamic loads due to seismic ground motion. (2) The DRKBA code cannot explicitly apply loads due to thermal stress. (3) The DRKBA

  2. Drift Degradation Analysis

    Energy Technology Data Exchange (ETDEWEB)

    D. Kicker

    2004-09-16

    Degradation of underground openings as a function of time is a natural and expected occurrence for any subsurface excavation. Over time, changes occur to both the stress condition and the strength of the rock mass due to several interacting factors. Once the factors contributing to degradation are characterized, the effects of drift degradation can typically be mitigated through appropriate design and maintenance of the ground support system. However, for the emplacement drifts of the geologic repository at Yucca Mountain, it is necessary to characterize drift degradation over a 10,000-year period, which is well beyond the functional period of the ground support system. This document provides an analysis of the amount of drift degradation anticipated in repository emplacement drifts for discrete events and time increments extending throughout the 10,000-year regulatory period for postclosure performance. This revision of the drift degradation analysis was developed to support the license application and fulfill specific agreement items between the U.S. Nuclear Regulatory Commission (NRC) and the U.S. Department of Energy (DOE). The earlier versions of ''Drift Degradation Analysis'' (BSC 2001 [DIRS 156304]) relied primarily on the DRKBA numerical code, which provides for a probabilistic key-block assessment based on realistic fracture patterns determined from field mapping in the Exploratory Studies Facility (ESF) at Yucca Mountain. A key block is defined as a critical block in the surrounding rock mass of an excavation, which is removable and oriented in an unsafe manner such that it is likely to move into an opening unless support is provided. However, the use of the DRKBA code to determine potential rockfall data at the repository horizon during the postclosure period has several limitations: (1) The DRKBA code cannot explicitly apply dynamic loads due to seismic ground motion. (2) The DRKBA code cannot explicitly apply loads due to thermal

  3. Chemical Emergencies

    Science.gov (United States)

    When a hazardous chemical has been released, it may harm people's health. Chemical releases can be unintentional, as in the case of an ... the case of a terrorist attack with a chemical weapon. Some hazardous chemicals have been developed by ...

  4. Degradation of fluorotelomer alcohols

    DEFF Research Database (Denmark)

    Ellis, David A; Martin, Jonathan W; De Silva, Amila O;

    2004-01-01

    Human and animal tissues collected in urban and remote global locations contain persistent and bioaccumulative perfluorinated carboxylic acids (PFCAs). The source of PFCAs was previously unknown. Here we present smog chamber studies that indicate fluorotelomer alcohols (FTOHs) can degrade....... The significance of the gas-phase peroxy radical cross reactions that produce PFCAs has not been recognized previously. Such reactions are expected to occur during the atmospheric degradation of all polyfluorinated materials, necessitating a reexamination of the environmental fate and impact of this important...... in the atmosphere to yield a homologous series of PFCAs. Atmospheric degradation of FTOHs is likely to contribute to the widespread dissemination of PFCAs. After their bioaccumulation potential is accounted for, the pattern of PFCAs yielded from FTOHs could account for the distinct contamination profile of PFCAs...

  5. Motor degradation prediction methods

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, J.R.; Kelly, J.F.; Delzingaro, M.J.

    1996-12-01

    Motor Operated Valve (MOV) squirrel cage AC motor rotors are susceptible to degradation under certain conditions. Premature failure can result due to high humidity/temperature environments, high running load conditions, extended periods at locked rotor conditions (i.e. > 15 seconds) or exceeding the motor`s duty cycle by frequent starts or multiple valve stroking. Exposure to high heat and moisture due to packing leaks, pressure seal ring leakage or other causes can significantly accelerate the degradation. ComEd and Liberty Technologies have worked together to provide and validate a non-intrusive method using motor power diagnostics to evaluate MOV rotor condition and predict failure. These techniques have provided a quick, low radiation dose method to evaluate inaccessible motors, identify degradation and allow scheduled replacement of motors prior to catastrophic failures.

  6. PWR degraded core analysis

    International Nuclear Information System (INIS)

    A review is presented of the various phenomena involved in degraded core accidents and the ensuing transport of fission products from the fuel to the primary circuit and the containment. The dominant accident sequences found in the PWR risk studies published to date are briefly described. Then chapters deal with the following topics: the condition and behaviour of water reactor fuel during normal operation and at the commencement of degraded core accidents; the generation of hydrogen from the Zircaloy-steam and the steel-steam reactions; the way in which the core deforms and finally melts following loss of coolant; debris relocation analysis; containment integrity; fission product behaviour during a degraded core accident. (U.K.)

  7. Motor degradation prediction methods

    International Nuclear Information System (INIS)

    Motor Operated Valve (MOV) squirrel cage AC motor rotors are susceptible to degradation under certain conditions. Premature failure can result due to high humidity/temperature environments, high running load conditions, extended periods at locked rotor conditions (i.e. > 15 seconds) or exceeding the motor's duty cycle by frequent starts or multiple valve stroking. Exposure to high heat and moisture due to packing leaks, pressure seal ring leakage or other causes can significantly accelerate the degradation. ComEd and Liberty Technologies have worked together to provide and validate a non-intrusive method using motor power diagnostics to evaluate MOV rotor condition and predict failure. These techniques have provided a quick, low radiation dose method to evaluate inaccessible motors, identify degradation and allow scheduled replacement of motors prior to catastrophic failures

  8. Survey of microbial degradation of asphalts with notes on relationship to nuclear waste management

    International Nuclear Information System (INIS)

    A survey has been made of the microbial degradation of asphalts. Topics covered include chemical and physical properties of asphalts, their chemical stability, methods of demonstrating their microbial degradation, and environmental extremes for microbial activity based on existing literature. Specific concerns for the use of asphalt in nuclear waste management, plus potential effects and consequences thereof are discussed. 82 references

  9. Photovoltaic Degradation Risk: Preprint

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-04-01

    The ability to accurately predict power delivery over the course of time is of vital importance to the growth of the photovoltaic (PV) industry. Important cost drivers include the efficiency with which sunlight is converted into power, how this relationship changes over time, and the uncertainty in this prediction. An accurate quantification of power decline over time, also known as degradation rate, is essential to all stakeholders - utility companies, integrators, investors, and researchers alike. In this paper we use a statistical approach based on historical data to quantify degradation rates, discern trends and quantify risks related to measurement uncertainties, number of measurements and methodologies.

  10. Photoredox degradation of different water pollutants (MO, RhB, MB, and Cr(VI)) using Fe–N–S-tri-doped TiO{sub 2} nanophotocatalyst prepared by novel chemical method

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Xuyao; Zhou, Xiaosong, E-mail: zxs801213@163.com; Zhang, Lingling; Xu, Limei; Ma, Lin; Luo, Jin; Li, Mengjia; Zeng, Lihua

    2015-10-15

    Highlights: • TiO{sub 2} was synthesized through simple one-step hydrothermal method. • Photocatalytic activity for degradation of organic dyes and Cr(VI) are investigated. • The synergistic effect is shown in coexistence of MB and Cr(VI). - Abstract: Fe–N–S-tri-doped TiO{sub 2} (FeNS-TiO{sub 2}) was synthesized by a simple one-step hydrothermal method. The as-synthesized samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). The photocatalytic activities of as-synthesized samples were tested by the oxidation of methyl orange (MO), rhodamine B (RhB), methylene blue (MB) and the reduction of aqueous Cr(VI) under visible-light (λ > 420 nm) irradiation, and compared with N-dope P25 (N-P25) and the undoped TiO{sub 2}. Besides, the effects of the coexistence of MO, RhB, and MB on FeNS-TiO{sub 2}-mediated photocatalytic reduction of aqueous Cr(VI) were also studied. The results indicated FeNS-TiO{sub 2} displayed higher visible-light-activated photocatalytic activity than N-P25 and the undoped TiO{sub 2}. Otherwise, FeNS-TiO{sub 2} showed the coexistence of MB enhanced the photocatalytic reduction of Cr(VI), whereas the coexistence of MO and RhB retarded the photocatalytic reduction of Cr(VI) over FeNS-TiO{sub 2}. Moreover, a possible photocatalytic mechanism is discussed.

  11. Chlorophyll Degradation in Horticultural Crops

    OpenAIRE

    Kaewsuksaeng, Samak

    2011-01-01

    One of the symptoms of senescence in harvested horticultural crops is the loss of greenness that comes with the degradation of chlorophyll. With senescence, the chlorophyll-degrading enzyme activities such as chlorophyllase, Mg-dechelatase or Mg-dechelation activity, a new chlorophyll-degrading enzyme, pheophytinase, pheophorbidase and chlorophyll-degrading peroxidase, which are involved in chlorophyll degradation, affected greatly in stored horticultural crops. The chlorophyll derivatives, e...

  12. Exploring methane-oxidizing communities for the co-metabolic degradation of organic micropollutants

    OpenAIRE

    Benner, Jessica; De Smet, Delfien; Ho, Adrian; Kerckhof, Frederiek-Maarten; Vanhaecke, Lynn; Heylen, Kim; Boon, Nico

    2015-01-01

    Methane-oxidizing cultures from five different inocula were enriched to be used for co-metabolic degradation of micropollutants. In a first screening, 18 different compounds were tested for degradation with the cultures as well as with four pure methane-oxidizing bacterial (MOB) strains. The tested compounds included pharmaceuticals, chemical additives, pesticides, and their degradation products. All enriched cultures were successful in the degradation of at least four different pollutants, b...

  13. Advice on Degradation Products in Pharmaceuticals: A Toxicological Evaluation.

    Science.gov (United States)

    Melo, Sâmia Rocha de Oliveira; Homem-de-Mello, Maurício; Silveira, Dâmaris; Simeoni, Luiz Alberto

    Degradation products are unwanted chemicals that can develop during the manufacturing, transportation, and storage of drug products and can affect the efficacy of pharmaceutical products. Moreover, even small amounts of degradation products can affect pharmaceutical safety because of the potential to cause adverse effects in patients. Consequently, it is crucial to focus on mechanistic understanding, formulation, storage conditions, and packaging to prevent the formation of degradation products that can negatively affect the quality and safety of the drug product. In this sense, databases and software that help predict the reactions involving the pharmaceutically active substance in the presence of degradation conditions can be used to obtain information on major degradation routes and the main degradation products formed during pharmaceutical product storage. In some cases, when the presence of a genotoxic degradation product is verified, it is necessary to conduct more thorough assessments. It is important to consider the chemical structure to distinguish between compounds with toxicologically alerting structures with associated toxic/genotoxic risks and compounds without active structures that can be treated as ordinary impurities. Evaluating the levels of degradation products based on a risk/benefit analysis is mandatory. Controlling critical variables during early development of drug products and conducting a follow-up study of these impurities can prevent degradation impurities present at concentrations greater than threshold values to ensure product quality. The definition of the impurity profile has become essential per various regulatory requirements. Therefore, this review includes the international regulatory perspective on impurity documents and the toxicological evaluation of degradation products. Additionally, some techniquesused in the investigation of degradation products and stability-indicating assay methods are highlighted.

  14. Drift Degradation Analysis

    International Nuclear Information System (INIS)

    The outputs from the drift degradation analysis support scientific analyses, models, and design calculations, including the following: (1) Abstraction of Drift Seepage; (2) Seismic Consequence Abstraction; (3) Structural Stability of a Drip Shield Under Quasi-Static Pressure; and (4) Drip Shield Structural Response to Rock Fall. This report has been developed in accordance with ''Technical Work Plan for: Regulatory Integration Modeling of Drift Degradation, Waste Package and Drip Shield Vibratory Motion and Seismic Consequences'' (BSC 2004 [DIRS 171520]). The drift degradation analysis includes the development and validation of rockfall models that approximate phenomenon associated with various components of rock mass behavior anticipated within the repository horizon. Two drift degradation rockfall models have been developed: the rockfall model for nonlithophysal rock and the rockfall model for lithophysal rock. These models reflect the two distinct types of tuffaceous rock at Yucca Mountain. The output of this modeling and analysis activity documents the expected drift deterioration for drifts constructed in accordance with the repository layout configuration (BSC 2004 [DIRS 172801])

  15. Detection of pump degradation

    Energy Technology Data Exchange (ETDEWEB)

    Greene, R.H.; Casada, D.A.; Ayers, C.W. [and others

    1995-08-01

    This Phase II Nuclear Plant Aging Research study examines the methods of detecting pump degradation that are currently employed in domestic and overseas nuclear facilities. This report evaluates the criteria mandated by required pump testing at U.S. nuclear power plants and compares them to those features characteristic of state-of-the-art diagnostic programs and practices currently implemented by other major industries. Since the working condition of the pump driver is crucial to pump operability, a brief review of new applications of motor diagnostics is provided that highlights recent developments in this technology. The routine collection and analysis of spectral data is superior to all other technologies in its ability to accurately detect numerous types and causes of pump degradation. Existing ASME Code testing criteria do not require the evaluation of pump vibration spectra but instead overall vibration amplitude. The mechanical information discernible from vibration amplitude analysis is limited, and several cases of pump failure were not detected in their early stages by vibration monitoring. Since spectral analysis can provide a wealth of pertinent information concerning the mechanical condition of rotating machinery, its incorporation into ASME testing criteria could merit a relaxation in the monthly-to-quarterly testing schedules that seek to verify and assure pump operability. Pump drivers are not included in the current battery of testing. Operational problems thought to be caused by pump degradation were found to be the result of motor degradation. Recent advances in nonintrusive monitoring techniques have made motor diagnostics a viable technology for assessing motor operability. Motor current/power analysis can detect rotor bar degradation and ascertain ranges of hydraulically unstable operation for a particular pump and motor set. The concept of using motor current or power fluctuations as an indicator of pump hydraulic load stability is presented.

  16. Development of forced degradation and stability indicating studies of drugs-A review

    Institute of Scientific and Technical Information of China (English)

    Blessy Mn; Ruchi D. Patel; Prajesh N. Prajapati; Y.K. Agrawal

    2014-01-01

    Forced degradation is a degradation of new drug substance and drug product at conditions more severe than accelerated conditions. It is required to demonstrate specificity of stability indicating methods and also provides an insight into degradation pathways and degradation products of the drug substance and helps in elucidation of the structure of the degradation products. Forced degradation studies show the chemical behavior of the molecule which in turn helps in the development of formulation and package. In addition, the regulatory guidance is very general and does not explain about the performance of forced degradation studies. Thus, this review discusses the current trends in performance of forced degradation studies by providing a strategy for conducting studies on degradation mechanisms and also describes the analytical methods helpful for development of stability indicating method.

  17. Soil degradation: a global problem endangering sustainable development

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Soil degradation, defined as lowering and losing of soil functions, is becoming more and more serious worldwide in recent decades, and poses a threat to agricultural production and terrestrial ecosystem. It is estimated that nearly 2 billion ha of soil resources in the world have been degraded,namely approximately 22% of the total cropland, pasture, forest, and woodland. Globally, soil erosion,chemical deterioration and physical degradation are the important parts amongst various types of soil degradation. As a natural process, soil degradation can be enhanced or dampened by a variety of human activities such as inappropriate agricultural management, overgrazing, deforestation, etc.Degraded soil means less food. As a result of soil degradation, it is estimated that about 11.9-13.4% of the global agricultural supply has been lost in the past five decades. Besides, soil degradation is also associated with off-site problems of sedimentation, climate change, watershed functions, and changes in natural habitats leading to loss of genetic stock and biodiversity. Therefore, it is essential to combat soil degradation at different levels and scales worldwide, not only for food security and ecological health, but also for the guarantee of global sustainable development.

  18. Oxidation Degradation of Aqueous Carbofuran Induced by Low Temperature Plasma

    Science.gov (United States)

    Pu, Lumei; Gao, Jinzhang; Hu, Yusen; Liang, Huiguang; Xiao, Wen; Wang, Xingmin

    2008-06-01

    The oxidative degradation of aqueous carbofuran, a heavily used toxic carbamate insecticide by low temperature plasma, was investigated. The results show that the treatment efficiency increases with the increase in initial concentration. Raising the treatment temperature and changing the pH value can result in enhanced degradation of carbofuran in solution. The results also show that low temperature plasma treatment can effectively remove chemical oxygen demand (COD) of carbofuran in the solution.

  19. Oxidation Degradation of Aqueous Carbofuran Induced by Low Temperature Plasma

    Institute of Scientific and Technical Information of China (English)

    PU Lumei; GAO Jinzhang; HU Yusen; LIANG Huiguang; XIAO Wen; WANG Xingmin

    2008-01-01

    The oxidative degradation of aqueous carbofuran, a heavily used toxic carbamate insecticide by low temperature plasma, was investigated. The results show that the treatment efficiency increases with the increase in initial concentration. Raising the treatment temperature and changing the pH value can result in enhanced degradation of carbofuran in solution. The results also show that low temperature plasma treatment can effectively remove chemical oxygen demand (COD) of carbofuran in the solution.

  20. Degradation mechanism of polyurethane foam induced by electron beam irradiation

    International Nuclear Information System (INIS)

    The degradation mechanism of irradiated polyurethane foam has been studied in detail. The changes of chemical structure and micro-phase separation have been determined by DTG. The gas products from irradiated samples are analyzed quantitatively and qualitatively by GC. The degradation mechanism of irradiated polyurethane foam has been deduced according to the experimental results. It provides some basis of the application on the polyurethane in the radiation field

  1. Degradation modelling of concrete submitted to sulfuric acid attack

    OpenAIRE

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

    2013-01-01

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

  2. Synthesis, characterization and degradation of some polyamines

    International Nuclear Information System (INIS)

    The present assignment deals with the synthesis, characterization and thermal degradation of poly-tertiary butyl aziridine (PTBA) and its copolymers with PMMA. Macro monomer of MMA and TBA was synthesised, its polymerisation and degradation studies were also conducted. Chapter one describes the major synthetic modes and the degradative processes in polymers and the ways and means to retard the degradation are also discussed. Chapter two includes the details of analytical and thermo analytical techniques used in the present research. Chapter three describes the methods employed for purification of chemicals, experimental details and data for the synthesis of monomers and polymers, characterization methodologies and isolation techniques. Chapter four includes the characterization of poly-tertiary butyl aziridine (PTBA) which was synthesised through cationic ring opening polymerization. Significant feature being the production of oligomers in bulk quantity which were collected as cold ring fraction. The mechanisms were proposed for the degradation products. Bifunctional anionic polymerisation of MMA to the desired molecular weight, end capping it with carbon disulfide, and block copolymer synthesis of PMMA with 'living' PTBA is included in chapter five. Chapter six includes the details of the modification procedure adopted for PMMA to generate desirable 'sites' on the polymer. Living PTBA segment were later grafted onto those sites to yield PMMA-g-PTBA. The TG, TVA and SATVA shows that the copolymer is quite stable and the degradation products are almost evenly distributed in liquid and cold ring fraction with very little condensable volatile fraction. In the final chapter the details of synthesis of a new monomer N-methyl-N-tert.butyl-amino ethyl-methacrylate (MTBAEM) are given. The polymerisation and characterization of the MTBAEM is discussed in details. Thermal analysis through TG, TVA and SATVA was conducted, the major fraction was collected at the cold ring

  3. Liquid chromatography and liquid chromatography-mass spectrometry analysis of donepezil degradation products

    Directory of Open Access Journals (Sweden)

    Mladenović Aleksandar R.

    2015-01-01

    Full Text Available This study describes the investigation of degradation products of donepezil (DP using stability indicating RP-HPLC method for determination of donepezil, which is a centrally acting reversible acetylcholinesterase inhibitor. In order to investigate the stability of drug and formed degradation products, a forced degradation study of drug sample and finished product under different forced degradation conditions has been conducted. Donepezil hydrochloride and donepezil tablets were subjected to stress degradation conditions recommended by International Conference on Harmonization (ICH. Donepezil hydrochloride solutions were subjected to acid and alkali hydrolysis, chemical oxidation and thermal degradation. Significant degradation was observed under alkali hydrolysis and oxidative degradation conditions. Additional degradation products were observed under the conditions of oxidative degradation. The degradation products observed during forced degradation studies were monitored using the high performance liquid chromatography (HPLC method developed. The parent method was modified in order to obtain LC-MS compatible method which was used to identify the degradation products from forced degradation samples using high resolution mass spectrometry. The mass spectrum provided the precise mass from which derived molecular formula of drug substance and degradation products formed and proved the specificity of the method unambiguously. [Projekat Ministarstva nauke Republike Srbije, br. 172013

  4. Degradation kinetics and mechanisms of phenolin photo-Fenton process

    Institute of Scientific and Technical Information of China (English)

    何锋; 雷乐成

    2004-01-01

    Phenol degradation in photochemically enhanced Fenton process was investigated in this work. UV-VIS spectra of phenol degradation showed the difference between photo-Fenton process and UV/H2O2, which is a typical hydroxyl radical process. A possible pathway diagram for phenol degradation in photo-Fenton process was proposed, and a mathematical model for chemical oxygen demand (COD) removal was developed. Operating parameters such as dosage of H2O2 and ferrous ions, pH, suitable carrier gas were found to impact the removal of COD significantly. The results and analysis of kinetic parameters calculated from the kinetic model showed that complex degradation of phenol was the main pathway for removal of COD: while hydroxyl radicals acted weakly in the photo-Fenton degradation of phenol.

  5. Nylon separators. [thermal degradation

    Science.gov (United States)

    Lim, H. S.

    1977-01-01

    A nylon separator was placed in a flooded condition in K0H solution and heated at various high temperatures ranging from 60 C to 110 C. The weight decrease was measured and the molecular weight and decomposition product were analyzed to determine: (1) the effect of K0H concentration on the hydrolysis rate; (2) the effect of K0H concentration on nylon degradation; (3) the activation energy at different K0H concentrations; and (4) the effect of oxygen on nylon degradation. The nylon hydrolysis rate is shown to increase as K0H concentration is decreased 34%, giving a maximum rate at about 16%. Separator hydrolysis is confirmed by molecular weight decrease in age of the batteries, and the reaction of nylon with molecular oxygen is probably negligible, compared to hydrolysis. The extrapolated rate value from the high temperature experiment correlates well with experimental values at 35 degrees.

  6. TALSPEAK Solvent Degradation

    Energy Technology Data Exchange (ETDEWEB)

    Leigh R. Martin; Bruce J. Mincher

    2009-09-01

    Understanding the radiolytic degradation behavior of organic molecules involved in new or existing schemes for the recycle of used nuclear fuels is of significant interest for sustaining a closed nuclear fuel cycle. Here we have conducted several lines of investigation to begin understanding the effects of radiolysis on the aqueous phase of the TALSPEAK process for the separation of the trivalent lanthanides from the trivalent actinides. Using the 60-Co irradiator at the INL, we have begun to quantify the effects of radiation on the aqueous phase complexants used in this separation technique, and how this will affect the actinide lanthanide separation factor. In addition we have started to develop methodologies for stable product identification, a key element in determining the degradation pathways. We have also introduced a methodology to investigate the effects of alpha radiolysis that has previously received limited attention.

  7. Plastics and beaches: A degrading relationship

    International Nuclear Information System (INIS)

    Plastic debris in Earth's oceans presents a serious environmental issue because breakdown by chemical weathering and mechanical erosion is minimal at sea. Following deposition on beaches, plastic materials are exposed to UV radiation and physical processes controlled by wind, current, wave and tide action. Plastic particles from Kauai's beaches were sampled to determine relationships between composition, surface textures, and plastics degradation. SEM images indicated that beach plastics feature both mechanically eroded and chemically weathered surface textures. Granular oxidation textures were concentrated along mechanically weakened fractures and along the margins of the more rounded plastic particles. Particles with oxidation textures also produced the most intense peaks in the lower wavenumber region of FTIR spectra. The textural results suggest that plastic debris is particularly conducive to both chemical and mechanical breakdown in beach environments, which cannot be said for plastics in other natural settings on Earth

  8. Prolamin degradation in sourdoughs

    OpenAIRE

    Loponen, Jussi

    2006-01-01

    This thesis examines protein behaviours that occur during cereal fermentations. The focus is on the prolamin degradation in sourdoughs. The thesis also looks at what happens to the oat globulins during an oat bran acidification process. The cereal prolamins are unique proteins in many respects. The wheat prolamins (glutenins and gliadins) are responsible for the formation of the gluten that provides the viscoelastic properties to wheat doughs whereas the rye prolamins (secalins) are unab...

  9. Gas generation from transuranic waste degradation: an interim assessment

    International Nuclear Information System (INIS)

    A review of all available, applicable data pertaining to gas generation from the degradation of transuranic waste matrix material and packaging is presented. Waste forms are representative of existing defense-related TRU wastes and include cellulosics, plastics, rubbers, concrete, process sludges, and mild steel. Degradation mechanisms studied were radiolysis, thermal, bacterial, and chemical corrosion. Gas generation rates are presented in terms of moles of gas produced per year per drum, and in G(gas) values for radiolytic degradation. Comparison of generation rates is made, as is a discussion of potential short- and long-term concerns. Techniques for reducing gas generation rates are discussed. 6 figures, 10 tables

  10. Caracterização física e química de áreas mineradas pela extração de cassiterita Physical and chemical characterization of the substratum of degraded areas by tin mining

    Directory of Open Access Journals (Sweden)

    Regina Márcia Longo

    2005-01-01

    Full Text Available O objetivo deste trabalho foi caracterizar as diferenças ocorridas, após a atividade da mineração de cassiterita, em uma área de floresta amazônica. As amostras foram coletadas, superficialmente, em área de mineração de cassiterita na Floresta Nacional do Jamari (RO, ao longo de uma linha compreendendo: floresta, capoeira, piso de lavra, área de deposição de rejeito seco e área de deposição de rejeito úmido. Em cada situação descrita foram coletadas cinco amostras, que serviram como repetição, totalizando 25. Nas amostras coletadas foram realizadas análises físicas e químicas. O processo de extração de cassiterita promoveu alterações significativas nos atributos dos solos estudados. A matéria orgânica, o fósforo disponível, a densidade de partículas e a resistência à penetração foram os mais alterados pelo processo de supressão da vegetação original e extração do minério.The present work had as objective to evaluate the differences in the substratum after tin mining in an area of amazon forest. The samples were collected, superficially, in an area of tin mining in the National Forest of Jamari, State of Rondonia, along a transect with: forest, forest regrowth, mining floor, dry tailing and moist tailing. In each situation 5 samples were collected, considered replicates, in a total of 25 samples. In the collected samples, physical and chemical analyses were accomplished. The obtained results allowed concluding that the process of tin extraction promoted significant alterations in the properties of the studied soils. Organic matter and P contents, bulk and particle density and resistance to penetration were the most affected by the processes of suppression of the original vegetation and tin extraction.

  11. Detection of pump degradation

    Energy Technology Data Exchange (ETDEWEB)

    Casada, D. [Oak Ridge National Lab., TN (United States)

    1995-04-01

    There are a variety of stressors that can affect the operation of centrifugal pumps. Although these general stressors are active in essentially all centrifugal pumps, the stressor level and the extent of wear and degradation can vary greatly. Parameters that affect the extent of stressor activity are manifold. In order to assure the long-term operational readiness of a pump, it is important to both understand the nature and magnitude of the specific degradation mechanisms and to monitor the performance of the pump. The most commonly applied method of monitoring the condition of not only pumps, but rotating machinery in general, is vibration analysis. Periodic or continuous special vibration analysis is a cornerstone of most pump monitoring programs. In the nuclear industry, non-spectral vibration monitoring of safety-related pumps is performed in accordance with the ASME code. Pump head and flow rate are also monitored, per code requirements. Although vibration analysis has dominated the condition monitoring field for many years, there are other measures that have been historically used to help understand pump condition; advances in historically applied technologies and developing technologies offer improved monitoring capabilities. The capabilities of several technologies (including vibration analysis, dynamic pressure analysis, and motor power analysis) to detect the presence and magnitude of both stressors and resultant degradation are discussed.

  12. Monitoring of Gasoline-ethanol Degradation In Undisturbed Soil

    Science.gov (United States)

    Österreicher-Cunha, P.; Nunes, C. M. F.; Vargas, E. A.; Guimarães, J. R. D.; Costa, A.

    Environmental contamination problems are greatly emphasised nowadays because of the direct threat they represent for human health. Traditional remediation methods fre- quently present low efficiency and high costs; therefore, biological treatment is being considered as an accessible and efficient alternative for soil and water remediation. Bioventing, commonly used to remediate petroleum hydrocarbon spills, stimulates the degradation capacity of indigenous microorganisms by providing better subsur- face oxygenation. In Brazil, gasoline and ethanol are mixed (78:22 v/v); some authors indicate that despite gasoline high degradability, its degradation in subsurface is hin- dered by the presence of much more rapidly degrading ethanol. Contaminant distribu- tion and degradation in the subsurface can be monitored by several physical, chemical and microbiological methodologies. This study aims to evaluate and follow the degra- dation of a gasoline-ethanol mixture in a residual undisturbed tropical soil from Rio de Janeiro. Bioventing was used to enhance microbial degradation. Shifts in bacte- rial culturable populations due to contamination and treatment effects were followed by conventional microbiology methods. Ground Penetrating Radar (GPR) measure- ments, which consist of the emission of electro-magnetic waves into the soil, yield a visualisation of contaminant degradation because of changes in soil conductivity due to microbial action on the pollutants. Chemical analyses will measure contaminant residue in soil. Our results disclosed contamination impact as well as bioventing stim- ulation on soil culturable heterotrophic bacterial populations. This multidisciplinary approach allows for a wider evaluation of processes occurring in soil.

  13. Glutaraldehyde degradation in hospital wastewater by photoozonation.

    Science.gov (United States)

    Kist, Lourdes Teresinha; Rosa, Ellen Caroline; Machado, Enio Leandro; Camargo, Maria Emilia; Moro, Celso Camilo

    2013-01-01

    In this paper, we assessed aqueous solutions of glutaraldehyde (GA), a chemical used for the disinfection of hospital materials, using advanced oxidative processes, O3, and UV, and the combination of the latter two. Assays with different ozone concentrations at distinct pH levels were conducted to determine the best treatment process. GA concentrations before and after each treatment were measured by spectrophotometry. The best treatment was that which combined O3 and UV, yielding a degradation of 72.0-75.0% in relation to the initial concentration with pH between 4 and 9. Kinetics demonstrated that GA degradation is not dependent on pH, as there was a first-order reaction with a rate constant of k = 0.0180 min(-1) for initial pH 9 and of k = 0.0179 min(-1) for initial pH 7, that is, the values are virtually the same. Secondary wastewater samples were also analysed using the septic tank/filter system of a regional hospital in Vale do Rio Pardo, state of Rio Grande do Sul, southern Brazil. In this case, the characteristics of the wastewater were described and, after treatment, a GA degradation rate of 23.3% was noted, with reductions of 75% for chemical oxygen demand, 81% for biochemical oxygen demand, 68% for turbidity, 70% for surfactants and total disinfection in terms of thermotolerant coliforms.

  14. Degradation of various dyes using Laccase enzyme.

    Science.gov (United States)

    Dhaarani, S; Priya, A K; Rajan, T Vel; Kartic, D Navamani

    2012-10-01

    Disposal of untreated dyeing effluent in water bodies, from textile industries, cause serious environmental and health hazards. The chemical structures of dye molecules are designed to resist fading on exposure to light or chemical attack, and they prove to be quite resistant towards microbial degradation. Therefore, current conventional biological processes may not be able to meet wastewater discharge criteria and reuse. An enzymatic treatment undergoes oxidative cleavage avoiding formation of toxic amines. Laccase is a multi-copper containing protein that catalyzes the oxidation of a wide range of aromatic substrates concomitantly with the reduction of molecular oxygen to water. UV visible spectral analysis of various synthetic dyes was performed in the study and wavelengths of maximum absorbance determined. Laccase enzyme was obtained from the fungi Pleorotus ostreatus. The enzyme showed high efficiency against Malachite Green, Basic Red and Acid Majanta with decolorization capacities of 97%, 94% and 94% respectively. Further, these dyes can be used for optimization of degradation parameters and analysis of degradation products.

  15. Glutaraldehyde degradation in hospital wastewater by photoozonation.

    Science.gov (United States)

    Kist, Lourdes Teresinha; Rosa, Ellen Caroline; Machado, Enio Leandro; Camargo, Maria Emilia; Moro, Celso Camilo

    2013-01-01

    In this paper, we assessed aqueous solutions of glutaraldehyde (GA), a chemical used for the disinfection of hospital materials, using advanced oxidative processes, O3, and UV, and the combination of the latter two. Assays with different ozone concentrations at distinct pH levels were conducted to determine the best treatment process. GA concentrations before and after each treatment were measured by spectrophotometry. The best treatment was that which combined O3 and UV, yielding a degradation of 72.0-75.0% in relation to the initial concentration with pH between 4 and 9. Kinetics demonstrated that GA degradation is not dependent on pH, as there was a first-order reaction with a rate constant of k = 0.0180 min(-1) for initial pH 9 and of k = 0.0179 min(-1) for initial pH 7, that is, the values are virtually the same. Secondary wastewater samples were also analysed using the septic tank/filter system of a regional hospital in Vale do Rio Pardo, state of Rio Grande do Sul, southern Brazil. In this case, the characteristics of the wastewater were described and, after treatment, a GA degradation rate of 23.3% was noted, with reductions of 75% for chemical oxygen demand, 81% for biochemical oxygen demand, 68% for turbidity, 70% for surfactants and total disinfection in terms of thermotolerant coliforms. PMID:24527619

  16. Modeling Degradation in Solid Oxide Electrolysis Cells

    Energy Technology Data Exchange (ETDEWEB)

    Manohar S. Sohal; Anil V. Virkar; Sergey N. Rashkeev; Michael V. Glazoff

    2010-09-01

    Idaho National Laboratory has an ongoing project to generate hydrogen from steam using solid oxide electrolysis cells (SOECs). To accomplish this, technical and degradation issues associated with the SOECs will need to be addressed. This report covers various approaches being pursued to model degradation issues in SOECs. An electrochemical model for degradation of SOECs is presented. The model is based on concepts in local thermodynamic equilibrium in systems otherwise in global thermodynamic no equilibrium. It is shown that electronic conduction through the electrolyte, however small, must be taken into account for determining local oxygen chemical potential, , within the electrolyte. The within the electrolyte may lie out of bounds in relation to values at the electrodes in the electrolyzer mode. Under certain conditions, high pressures can develop in the electrolyte just near the oxygen electrode/electrolyte interface, leading to oxygen electrode delamination. These predictions are in accordance with the reported literature on the subject. Development of high pressures may be avoided by introducing some electronic conduction in the electrolyte. By combining equilibrium thermodynamics, no equilibrium (diffusion) modeling, and first-principles, atomic scale calculations were performed to understand the degradation mechanisms and provide practical recommendations on how to inhibit and/or completely mitigate them.

  17. Microbially influenced degradation of concrete structures

    Science.gov (United States)

    Rogers, Robert D.; Hamilton, Melinda A.; Nelson, Lee O.

    1998-03-01

    Steel reinforced concrete is the most widely used construction material in the world. The economic costs of repair or replacement of environmentally damaged concrete structures is astronomical. For example, half of the concrete bridges in the Federal Department of Transportation highway system are in need of major repairs. Microbially influenced degradation of concrete (MID) is one of the recognized degradative processes known to adversely affect concrete integrity. It is not possible to assign a specific percent of effect to any of these processes. However, MID has been shown to be as aggressive as any of the physical/chemical phenomena. In addition, the possibility exists that there is a synergism which results in cumulative effects from all the processes. Three groups of bacteria are known to promote MID. Of these, sulfur-oxidizing bacteria (SOB) are the most aggressive. Much is known about the nutritional needs of these bacteria. However, there has not been a biological linkage established between the presence of environmental, polluting sulfur sources and the degradation of concrete structures. It has been shown that the environmental pollutants sulfur dioxide and sulfite can be utilized by active SOB for the biological production of sulfuric acid. Therefore, it is not a reach of reality to assume that SOB exposed to these pollutants could have a major impact on the degradation of concrete structures. But, until the environment sulfur loop is closed it will not be possible to calculate how important SOB activity is in initiating and promoting damage.

  18. Biogeochemical Cycles in Degraded Lands

    Science.gov (United States)

    Davidson, Eric A.; Vieira, Ima Celia G.; ReisdeCarvalho, Claudio Jose; DeanedeAbreuSa, Tatiana; deSouzaMoutinho, Paulo R.; Figueiredo, Ricardo O.; Stone, Thomas A.

    2004-01-01

    The objectives of this project were to define and describe the types of landscapes that fall under the broad category of "degraded lands" and to study biogeochemical cycles across this range of degradation found in secondary forests. We define degraded land as that which has lost part of its capacity of renovation of a productive ecosystem, either in the context of agroecosystems or as native communities of vegetation. This definition of degradation permits evaluation of biogeochemical constraints to future land uses.

  19. Hydrolytic and oxidative degradation of electrospun supramolecular biomaterials: In vitro degradation pathways.

    Science.gov (United States)

    Brugmans, M C P; Sӧntjens, S H M; Cox, M A J; Nandakumar, A; Bosman, A W; Mes, T; Janssen, H M; Bouten, C V C; Baaijens, F P T; Driessen-Mol, A

    2015-11-01

    The emerging field of in situ tissue engineering (TE) of load bearing tissues places high demands on the implanted scaffolds, as these scaffolds should provide mechanical stability immediately upon implantation. The new class of synthetic supramolecular biomaterial polymers, which contain non-covalent interactions between the polymer chains, thereby forming complex 3D structures by self assembly. Here, we have aimed to map the degradation characteristics of promising (supramolecular) materials, by using a combination of in vitro tests. The selected biomaterials were all polycaprolactones (PCLs), either conventional and unmodified PCL, or PCL with supramolecular hydrogen bonding moieties (either 2-ureido-[1H]-pyrimidin-4-one or bis-urea units) incorporated into the backbone. As these materials are elastomeric, they are suitable candidates for cardiovascular TE applications. Electrospun scaffold strips of these materials were incubated with solutions containing enzymes that catalyze hydrolysis, or solutions containing oxidative species. At several time points, chemical, morphological, and mechanical properties were investigated. It was demonstrated that conventional and supramolecular PCL-based polymers respond differently to enzyme-accelerated hydrolytic or oxidative degradation, depending on the morphological and chemical composition of the material. Conventional PCL is more prone to hydrolytic enzymatic degradation as compared to the investigated supramolecular materials, while, in contrast, the latter materials are more susceptible to oxidative degradation. Given the observed degradation pathways of the examined materials, we are able to tailor degradation characteristics by combining selected PCL backbones with additional supramolecular moieties. The presented combination of in vitro test methods can be employed to screen, limit, and select biomaterials for pre-clinical in vivo studies targeted to different clinical applications. PMID:26316031

  20. Hydrolytic and oxidative degradation of electrospun supramolecular biomaterials: In vitro degradation pathways.

    Science.gov (United States)

    Brugmans, M C P; Sӧntjens, S H M; Cox, M A J; Nandakumar, A; Bosman, A W; Mes, T; Janssen, H M; Bouten, C V C; Baaijens, F P T; Driessen-Mol, A

    2015-11-01

    The emerging field of in situ tissue engineering (TE) of load bearing tissues places high demands on the implanted scaffolds, as these scaffolds should provide mechanical stability immediately upon implantation. The new class of synthetic supramolecular biomaterial polymers, which contain non-covalent interactions between the polymer chains, thereby forming complex 3D structures by self assembly. Here, we have aimed to map the degradation characteristics of promising (supramolecular) materials, by using a combination of in vitro tests. The selected biomaterials were all polycaprolactones (PCLs), either conventional and unmodified PCL, or PCL with supramolecular hydrogen bonding moieties (either 2-ureido-[1H]-pyrimidin-4-one or bis-urea units) incorporated into the backbone. As these materials are elastomeric, they are suitable candidates for cardiovascular TE applications. Electrospun scaffold strips of these materials were incubated with solutions containing enzymes that catalyze hydrolysis, or solutions containing oxidative species. At several time points, chemical, morphological, and mechanical properties were investigated. It was demonstrated that conventional and supramolecular PCL-based polymers respond differently to enzyme-accelerated hydrolytic or oxidative degradation, depending on the morphological and chemical composition of the material. Conventional PCL is more prone to hydrolytic enzymatic degradation as compared to the investigated supramolecular materials, while, in contrast, the latter materials are more susceptible to oxidative degradation. Given the observed degradation pathways of the examined materials, we are able to tailor degradation characteristics by combining selected PCL backbones with additional supramolecular moieties. The presented combination of in vitro test methods can be employed to screen, limit, and select biomaterials for pre-clinical in vivo studies targeted to different clinical applications.

  1. Degradation of p-Nitrophenol on Biochars: Role of Persistent Free Radicals.

    Science.gov (United States)

    Yang, Jing; Pan, Bo; Li, Hao; Liao, Shaohua; Zhang, Di; Wu, Min; Xing, Baoshan

    2016-01-19

    Generation of environmentally persistent free radicals (EPFRs) on solid particles has recently attracted increasing research interest. EPFRs potentially have high reactivity and toxicity. However, the impact of EPFRs on organic contaminant behavior is unclear. We hypothesized that EPFRs in biochars can degrade organic contaminants and play an important role in organic contaminant behavior. We observed obvious degradation of p-nitrophenol (PNP) in the presence of biochars, through the detection of NO3(-) as well as organic byproducts. The extent of PNP degradation was correlated to the intensity of EPR signals of biochar particles. tert-Butanol (a •OH scavenger) did not completely inhibit PNP degradation, indicating that •OH could not fully explain PNP degradation. The decreased PNP degradation after tert-butanol addition was better correlated with reduced PNP sorption on biochars. PNP degradation through the direct contact with EPFRs in biochar particles could be an important contribution to the PNP concentration reduction in the aqueous phase. The coating of natural organic matter analogue (tannic acid) on biochars did not considerably inhibit PNP degradation, suggesting the ability of biochars to degrade PNP in soil and natural water. Similar EPFR-promoted degradation was observed for five different types of biochars and one activated carbon, as well as one additional chemical (p-aminophenol). Therefore, organic chemical degradation by EPFRs in biochars can be a common process in the environment and should be incorporated in organic chemical fate and risk studies.

  2. Degradation of copepod fecal pellets

    DEFF Research Database (Denmark)

    Poulsen, Louise K.; Iversen, Morten

    2008-01-01

    from 22% d(-1) (July 2005) to 87% d(-1) (May). Protozooplankton (dinoflagellates and ciliates) in the size range of 20 to 100 mu m were the key degraders of the fecal pellets, contributing from 15 to 53% of the total degradation rate. Free-living in situ bacteria did not affect pellet degradation rate...

  3. Degradation of polychlorinated naphthalene by mechanochemical treatment.

    Science.gov (United States)

    Nomura, Yugo; Aono, Sho; Arino, Takashi; Yamamoto, Takashi; Terada, Akihiko; Noma, Yukio; Hosomi, Masaaki

    2013-11-01

    Polychlorinated naphthalene (PCN) is a hazardous compound that is listed as a new persistent organic pollutants candidate by the United Nations Environment Program. The production, import and use of PCNs are prohibited by the Chemical Substances Control Law in Japan. PCN was milled with calcium oxide as an additive to investigate the feasibility of its degradation by mechanochemical treatment. The milling process cleaved the C-C and C-Cl bonds by the mechanically induced solid-state reaction. Gas chromatography/mass spectrometry analysis confirmed that the PCN was decomposed after 1h milling. The yield of chloride ions reached 100% after 3h milling. This indicates that all PCN was broken down into inorganic compounds after milling, thereby maintaining the chlorine mass balance through the reaction. This experiment, for the first time, exhibited the effectiveness of mechanochemical treatment as a PCN degradation method.

  4. Aflatoxin B1 Degradation by a Pseudomonas Strain

    Science.gov (United States)

    Sangare, Lancine; Zhao, Yueju; Folly, Yawa Minnie Elodie; Chang, Jinghua; Li, Jinhan; Selvaraj, Jonathan Nimal; Xing, Fuguo; Zhou, Lu; Wang, Yan; Liu, Yang

    2014-01-01

    Aflatoxin B1 (AFB1), one of the most potent naturally occurring mutagens and carcinogens, causes significant threats to the food industry and animal production. In this study, 25 bacteria isolates were collected from grain kernels and soils displaying AFB1 reduction activity. Based on its degradation effectiveness, isolate N17-1 was selected for further characterization and identified as Pseudomonas aeruginosa. P. aeruginosa N17-1 could degrade AFB1, AFB2 and AFM1 by 82.8%, 46.8% and 31.9% after incubation in Nutrient Broth (NB) medium at 37 °C for 72 h, respectively. The culture supernatant of isolate N17-1 degraded AFB1 effectively, whereas the viable cells and intra cell extracts were far less effective. Factors influencing AFB1 degradation by the culture supernatant were investigated. Maximum degradation was observed at 55 °C. Ions Mn2+ and Cu2+ were activators for AFB1 degradation, however, ions Mg2+, Li+, Zn2+, Se2+, Fe3+ were strong inhibitors. Treatments with proteinase K and proteinase K plus SDS significantly reduced the degradation activity of the culture supernatant. No degradation products were observed based on preliminary LC-QTOF/MS analysis, indicating AFB1 was metabolized to degradation products with chemical properties different from that of AFB1. The results indicated that the degradation of AFB1 by P. aeruginosa N17-1 was enzymatic and could have a great potential in industrial applications. This is the first report indicating that the isolate of P. aeruginosa possesses the ability to degrade aflatoxin. PMID:25341538

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

    Science.gov (United States)

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

    2013-07-01

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

  6. Restoring Soil Quality to Mitigate Soil Degradation

    Directory of Open Access Journals (Sweden)

    Rattan Lal

    2015-05-01

    Full Text Available Feeding the world population, 7.3 billion in 2015 and projected to increase to 9.5 billion by 2050, necessitates an increase in agricultural production of ~70% between 2005 and 2050. Soil degradation, characterized by decline in quality and decrease in ecosystem goods and services, is a major constraint to achieving the required increase in agricultural production. Soil is a non-renewable resource on human time scales with its vulnerability to degradation depending on complex interactions between processes, factors and causes occurring at a range of spatial and temporal scales. Among the major soil degradation processes are accelerated erosion, depletion of the soil organic carbon (SOC pool and loss in biodiversity, loss of soil fertility and elemental imbalance, acidification and salinization. Soil degradation trends can be reversed by conversion to a restorative land use and adoption of recommended management practices. The strategy is to minimize soil erosion, create positive SOC and N budgets, enhance activity and species diversity of soil biota (micro, meso, and macro, and improve structural stability and pore geometry. Improving soil quality (i.e., increasing SOC pool, improving soil structure, enhancing soil fertility can reduce risks of soil degradation (physical, chemical, biological and ecological while improving the environment. Increasing the SOC pool to above the critical level (10 to 15 g/kg is essential to set-in-motion the restorative trends. Site-specific techniques of restoring soil quality include conservation agriculture, integrated nutrient management, continuous vegetative cover such as residue mulch and cover cropping, and controlled grazing at appropriate stocking rates. The strategy is to produce “more from less” by reducing losses and increasing soil, water, and nutrient use efficiency.

  7. Effects of compound chemical treatment on dry matter and fiber degradation rate of wheat straw in rumen%复合化学处理对麦秸干物质和纤维瘤胃降解率的影响

    Institute of Scientific and Technical Information of China (English)

    孙国强; 吕永艳; 崔海净; 蔡李逢

    2012-01-01

    To investigate effects of compound chemical treatment on dry matter( DM) and fiber degradation rate of wheat straw in rumen, urea and calcium hydroxide were added on the basis of straw air-dried matter with 2% , 3% and 4% respectively, a total of nine experimental groups, urea and calcium hydroxide added in groupl to group9 in turn were: 2% + 2% , 2% + 3% , 2% +4% , 3% +2% , 3% +3% , 3% +4% , 4% +2% , 4% +3% and4% + 4% ,the control(CK) group was the original wheat straw, DM and fiber degradation rate after 72 hours of different treatments for straw were measured by short-term artificial rumen technique. The results showed that: group 7, 8 and 9 were significantly higher than CK group and other experimental groups (P 0. 05) among group 7,8 and 9. Group 7 and 8 were significantly higher than CK group and other six experimental groups (P <0. 01) in neutral detergent fiber ( NDF) degradation rate after 72 hours, which was increased by 92. 06% , 82. 51 % respectively, and significantly higher than that of group 9 (P < 0. 05 ). Under this experimental condition, the treatment added with 4% urea and 2% calcium hydroxide of wheat straw air-dried matter was the most suitable compound chemical treatment.%为了研究复合化学处理对麦秸干物质和纤维瘤胃降解率的影响,本试验将尿素和氢氧化钙均按麦秸风干重2%,3%和4%的量分别添加,共9个试验组,各试验组尿素和氢氧化钙的添加量依次为1组2%+2%,2组2%+3%,3组2%+4%,4组3%+2%,5组3%+3%,6组3%+4%,7组4%+2%,8组4%+3%和9组4%+4%,对照组为原麦秸,通过短期人工瘤胃技术测定不同复合处理麦秸干物质和纤维的瘤胃72 h降解率.结果表明:7组,8组和9组三个组的干物质和酸性洗涤纤维瘤胃72 h降解率极显著高于对照组和其他试验组(P<0.01);干物质和酸性洗涤纤维瘤胃72 h降解率分别比对照组提高90.96%,85.24%,75.03%和139.38%,132.06%,130.94%;7组和8组

  8. Rat myocardial protein degradation.

    Science.gov (United States)

    Steer, J H; Hopkins, B E

    1981-07-01

    1. Myocardial protein degradation rates were determined by following tyrosine release from rat isolated left hemi-atria in vitro. 2. After two 20 min preincubations the rate of tyrosine release from hemi-atria was constant for 4 h. 3. Skeletal muscle protein degradation was determined by following tyrosine release from rat isolated hemi-diaphragm (Fulks, Li & Goldberg, 1975). 4. Insulin (10(-7) M) inhibited tyrosine release from hemi-atria and hemi-diaphragm to a similar extent. A 48 h fast increased tyrosine release rate from hemi-diaphragm and decreased tyrosine release rate from hemi-atria. Hemi-diaphragm tyrosine release was inhibited by 15 mmol/l D-glucose but a variety of concentrations of D-glucose (0, 5, 15 mmol/l) had no effect on tyrosine release from hemi-atria. Five times the normal plasma levels of the branched-chain amino acids leucine, isoleucine and valine had no effect on tyrosine release from either hemi-atria or hemi-diaphragm.

  9. The microbial degradation of azo dyes: minireview.

    Science.gov (United States)

    Chengalroyen, M D; Dabbs, E R

    2013-03-01

    The removal of dyes in wastewater treatment plants still involves physical or chemical processes. Yet numerous studies currently exist on degradation based on the use of microbes-which is a well-studied field. However progress in the use of biological methods to deal with this environmentally noxious waste is currently lacking. This review focuses on the largest dye class, that is azo dyes and their biodegradation. We summarize the bacteria identified thus far which have been implicated in dye decolorization and discuss the enzymes involved and mechanisms by which these colorants are broken down.

  10. Synthesis and application of novel degradable crosslinkers

    Institute of Scientific and Technical Information of China (English)

    Xin Ce Sui; Zhi Feng Fu; Yan Shi

    2011-01-01

    A novel divinyl ether was synthesized by a convenient method with high yield. Then the divinyl ether was combined with 2-hydroxyethyl methacrylate and acrylic acid, respectively, generating difunctional polymeric crosslinkers with (hemi)acetal structure that was labile in acid. The chemical structures of the divinyl ether and crosslinkers were confirmed by 1H NMR and elemental analysis. The crosslinkers were employed in free-radical polymerization to prepare polymer gel and gel particles. Due to the (hemi)acetal structure in the crosslinking segment, the polymer gel and particles exhibited degradable ability in strong acid.

  11. Biological degradation of heavy mineral soaps

    Energy Technology Data Exchange (ETDEWEB)

    Glombitza, F.; Iske, U.; Bullmann, M.

    1988-11-01

    The possibility of biological degradation is exemplified by a chemically highly resistant Zircon mineral of the heavy mineral soaps of the Baltic Sea, with the aid of Thiobacillus ferrooxidans and Acetobacter spec. strains. The total matrix of the mineral is dissolved and all trace elements contained are solubilized. The different mechanisms of the leaching reaction give different distributions of the dissolved compounds in the phases of the leaching system. Concerning the REE a selectivity based on their physical characteristics is observed. There is a preferential solution of the light REE as compared to the heavy REE. The conditions of use are discussed.

  12. Microbial degradation of poly-beta-hydroxyalkanoates.

    Science.gov (United States)

    Mas-Castellà, J; Lafuente, R; Urmeneta, J; Goodwin, S; Guerrero, R

    1994-01-01

    The search for new materials that are not hazardous to the environment has become a major issue in our society, engaged as it is in the attainment of sustainable development. Poly-beta-hydroxyalkanoates (PHA), produced exclusively by prokaryotes, can be used as thermoplastics and are fully biodegradable and innocuous to the environment. Biodegradability testing has quantified the capacity of microorganisms to degrade such new chemical compounds, particularly polyhydroxyalkanoates. Standardized tests may also discover new microorganisms and environmental conditions that accelerate biodegradation. We evaluate various techniques used to assess the biodegradability of PHA, and which may also be applied to test other kinds of polymers.

  13. Chemical Composition, Energetic Values and Ruminal Degradation Characteristics of Different Portions of Cornstalks Derived from Skin-Pith Separation%皮瓤分离玉米秸不同部分的化学成分、能量价值和瘤胃降解特性

    Institute of Scientific and Technical Information of China (English)

    周涛; 杨钦兰; 张统雨; 周振明; 任丽萍; 孟庆翔; 白元生

    2015-01-01

    This study was conducted to using chemical analysis, model prediction and in situ nylon bag meth-ods to compare chemical composition, energetic values and ruminal degradation characteristics of different por-tions of cornstalks derived from an industry skin-pith separation process in a completely randomized single-fac-torial design. Through simulation of the industry skins-pith separation process using stem-skins as industry plank materials, the cornstalks were manually separated into five portions: leaves, husks, cob, stem-pith and stem-skins, and the whole-plant cornstalk was used as control. The results showed as follows: 1 ) among different portions of cornstalk, leaves accounted for the highest proportion ( 31. 02%) , followed by stem-skins (29.39%), cob (18.93%), husks (10.87%) and stem-pith (9.69%) in whole-plant. 2) There were signifi-cant differences in chemical composition among different portions of cornstalks (Pstem-pith>leaves>cob.%本试验采用化学分析、模型预测和尼龙袋技术分析了皮瓤分离玉米秸不同部分的化学成分、能量价值和瘤胃降解特性。采用单因子完全随机化试验设计,模拟玉米秸茎皮作为建筑业新材料的秸秆分离工艺,将玉米秸人工分离为茎叶、苞叶、芯轴、茎皮和茎髓5个部分,以整株玉米秸作为对照。结果表明:1)皮瓤分离玉米秸各部分中,茎叶占全株比例最高(31.02%),茎皮(29.39%)次之,随后为芯轴(18.93%)、苞叶(10.87%)和茎髓(9.69%)。2)玉米秸各部分间化学成分含量存在显著差异(P茎髓>茎叶>芯轴。

  14. Biomass pyrolysis for chemicals

    Energy Technology Data Exchange (ETDEWEB)

    De Wild, P.

    2011-07-15

    The problems associated with the use of fossil fuels demand a transition to renewable sources (sun, wind, water, geothermal, biomass) for materials and energy where biomass provides the only renewable source for chemicals. In a biorefinery, biomass is converted via different technologies into heat, power and various products. Here, pyrolysis (thermal degradation without added oxygen) of lignocellulosic biomass can play an important role, because it leads to an array of useful chemicals. Examples are furfural and acetic acid from hemicellulose, levoglucosan from cellulose and phenols and biochar from lignin. Since the three major biomass polymers hemicellulose, cellulose and lignin possess dissimilar thermal stabilities and reactivities, type and amount of degradation products are tunable by proper selection of the pyrolysis conditions. To determine if step-wise pyrolysis would be suitable for the production of chemicals, staged degasification of lignocellulosic biomass was studied. Due to limited yields, a hot pressurized water pre-treatment (aquathermolysis) followed by pyrolysis was subsequently developed as an improved version of a staged approach to produce furfural and levoglucosan from the carbohydrate fraction of the biomass. Lignin is the only renewable source for aromatic chemicals. Lignocellulosic biorefineries for bio-ethanol produce lignin as major by-product. The pyrolysis of side-streams into valuable chemicals is of prime importance for a profitable biorefinery. To determine the added-value of lignin side-streams other than their use as fuel for power, application research including techno-economic analysis is required. In this thesis, the pyrolytic valorisation of lignin into phenols and biochar was investigated and proven possible.

  15. Thermal battery degradation mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Missert, Nancy A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Brunke, Lyle Brent [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-09-01

    Diffuse reflectance IR spectroscopy (DRIFTS) was used to investigate the effect of accelerated aging on LiSi based anodes in simulated MC3816 batteries. DRIFTS spectra showed that the oxygen, carbonate, hydroxide and sulfur content of the anodes changes with aging times and temperatures, but not in a monotonic fashion that could be correlated to phase evolution. Bands associated with sulfur species were only observed in anodes taken from batteries aged in wet environments, providing further evidence for a reaction pathway facilitated by H2S transport from the cathode, through the separator, to the anode. Loss of battery capacity with accelerated aging in wet environments was correlated to loss of FeS2 in the catholyte pellets, suggesting that the major contribution to battery performance degradation results from loss of active cathode material.

  16. The Effect of the PLA Degradation Chemical on cell Proliferation

    Science.gov (United States)

    Feng, Kuan-Che

    PLA is a material easy to manufacture. The biodegradability makes it a perfect material for tissue engineering. Several conditions for biodegradability experiments for spin-coating Polylactic acid thin films were tried. Polylactic acid thin films were immersed in different solution for different times. Thickness, morphology and mechanical properties were analyzed after the Polylactic acid thin films immersing test. Dermal fibroblasts were plated on the Polylactic acid thin films, culturing with conditioning medium. Thickness, morphology, mechanical properties and cell count were analyzed after the Polylactic acid thin films cell culture test.

  17. Transport and degradation of contaminants in the vadose zone

    NARCIS (Netherlands)

    Schotanus, D.

    2013-01-01

    Leaching of contaminants from the vadose zone to the groundwater depends on the soil properties and the infiltration rate. In this thesis, organic degradable contaminants were studied, such as de-icing chemicals (consisting of propylene glycol, PG) and pesticides. Heterogeneous soil properties lead

  18. Chemical use

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This is a summary of research and activities related to chemical use on Neal Smith National Wildlife Refuge between 1992 and 2009. The chemicals used on the Refuge...

  19. Chemical Reactors.

    Science.gov (United States)

    Kenney, C. N.

    1980-01-01

    Describes a course, including content, reading list, and presentation on chemical reactors at Cambridge University, England. A brief comparison of chemical engineering education between the United States and England is also given. (JN)

  20. Generic Degraded Configuration Probability Analysis for the Codisposal Waste Package

    International Nuclear Information System (INIS)

    In accordance with the technical work plan, ''Technical Work Plan For: Department of Energy Spent Nuclear Fuel Work Packages'' (CRWMS M and O 2000c), this Analysis/Model Report (AMR) is developed for the purpose of screening out degraded configurations for U.S. Department of Energy (DOE) spent nuclear fuel (SNF) types. It performs the degraded configuration parameter and probability evaluations of the overall methodology specified in the ''Disposal Criticality Analysis Methodology Topical Report'' (YMP 2000, Section 3) to qualifying configurations. Degradation analyses are performed to assess realizable parameter ranges and physical regimes for configurations. Probability calculations are then performed for configurations characterized by keff in excess of the Critical Limit (CL). The scope of this document is to develop a generic set of screening criteria or models to screen out degraded configurations having potential for exceeding a criticality limit. The developed screening criteria include arguments based on physical/chemical processes and probability calculations and apply to DOE SNF types when codisposed with the high-level waste (HLW) glass inside a waste package. The degradation takes place inside the waste package and is long after repository licensing has expired. The emphasis of this AMR is on degraded configuration screening and the probability analysis is one of the approaches used for screening. The intended use of the model is to apply the developed screening criteria to each DOE SNF type following the completion of the degraded mode criticality analysis internal to the waste package

  1. Aggregate stability and soil degradation in the tropics

    International Nuclear Information System (INIS)

    Aggregate stability is a measure of the structural stability of soils. Factors that influence aggregate stability are important in evaluating the ease with which soils erode by water and/or wind, the potential of soils to crust and/or seal, soil permeability, quasi-steady state infiltration rates and seedling emergence and in predicting the capacity of soils to sustain long-term crop production. Aggregate stability of soils can be measured by the wet-sieving or raindrop techniques. A reduction in soil aggregate stability implies an increase in soil degradation. Hence aggregate stability and soil degradation are interwoven. The measures used can either be preventive or remedial. Preventive practices minimize the chances of soil degradation occurring or the magnitude or severity of the damage when the degradation manifests. These include in Nigeria, (i) manuring and mulching, (ii) planted fallows and cover crops, (iii) sustainable farming systems, (iv) adequate rotations, (v) home gardens or compound farms, (vi) alley cropping and related agro forestry systems, and (vii) chemical fertilizers which are mainly remedial measures. Because of alterations in soil properties that affect particular land uses, soils may degrade for one crop (maize rather sorghum). As long as some land use is possible soil degradation is not always an absolute concept. Decline in agricultural productivity should be evaluated in terms of inputs such as fertilizer use, water management and tillage methods. We can alleviate some types of soil degradation by use of micronutrients, inorganic fertilizers and organic residues. Soil that responds to management practices cannot be said to be degraded. Since crop growth depends on weather, degraded soils may be more sensitive to harsh weather (e.g. drought, temperature) than undegraded soils. A soil is degraded if its productivity falls below the economic threshold even under favourable weather conditions or with judicious inputs. All human

  2. Chemical sensor

    Science.gov (United States)

    Rauh, R. David (Inventor)

    1990-01-01

    A sensor for detecting a chemical substance includes an insertion element having a structure which enables insertion of the chemical substance with a resulting change in the bulk electrical characteristics of the insertion element under conditions sufficient to permit effective insertion; the change in the bulk electrical characteristics of the insertion element is detected as an indication of the presence of the chemical substance.

  3. Sonochemical Degradation of Perfluorooctane Sulfonate (PFOS) and Perfluorooctanoate (PFOA) in Groundwater: Kinetic Effects of Matrix Inorganics

    OpenAIRE

    Cheng, Jie; vecitis, Chad D.; Park, Hyunwoong; Mader, Brian T.; Hoffmann, Michael R.

    2010-01-01

    Ultrasonic irradiation has been shown to effectively degrade perfluorinated chemicals (PFCs) such as perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) in aqueous solution. Reduced PFC sonochemical degradation rates in organic-rich groundwater taken from beneath a landfill, however, testify to the negative kinetic effects of the organic groundwater constituents. In this study, the PFOX (X = S or A) sonochemical degradation rates in a groundwater sample with organic concentrations ...

  4. Biogenic amines degradation by malolactic bacteria: towards a potential application in wine

    OpenAIRE

    GiuseppeSpano; VittorioCapozzi; Alvarez, Miguel A.; DanielaFiocco; FrancescoGrieco

    2012-01-01

    Biogenic amines in wine represent a toxicological risk for the health of the consumer, with several trade implications. In this study 26 strains of Lactobacillus plantarum were analysed for their ability to degrade biogenic amines commonly found during wine fermentation. Two strains of L. plantarum were selected in reason of their ability to degrade putrescine and tyramine. The degradation was assessed in vitro, both in presence of the biogenic amines and in presence of the specific chemical ...

  5. Biogenic amines degradation by Lactobacillus plantarum: toward a potential application in wine

    OpenAIRE

    Capozzi, Vittorio; Russo, Pasquale; Ladero, Victor; Fernández, María; Fiocco, Daniela; Alvarez, Miguel A.; Grieco, Francesco; Spano, Giuseppe

    2012-01-01

    Biogenic amines in wine represent a toxicological risk for the health of the consumer, with several trade implications. In this study 26 strains of Lactobacillus plantarum were analysed for their ability to degrade biogenic amines commonly found during wine fermentation. Two strains of L. plantarum were selected in reason of their ability to degrade putrescine and tyramine. The degradation was assessed in vitro, both in presence of the biogenic amines and in presence of the specific chemical ...

  6. Emission of reactive oxygen species during degradation of iron gall ink

    OpenAIRE

    Strlič, M.; Menart, E.; Cigić, I. K.; Kolar, J; de Bruin, G.; Cassar, M.

    2010-01-01

    Iron gall inks are characterised by high contents of acids and transition metals, promoting degradation of cellulose due to hydrolysis and oxidation, respectively. Their chemical interaction with the environment is not well understood, especially in view of emissions of degradation products which could lead to spread of degradation processes. In order to study the emissions, we employed gas chromatography/mass spectrometry following headspace micro-extraction, and liquid chromatography fol...

  7. 退化高寒草旬土壤有机碳分布特征及与土壤理化性质的关系%Distribution of soil organic carbon and its relationship with soil physical and chemical properties on degraded alpine meadows

    Institute of Scientific and Technical Information of China (English)

    曹丽花; 刘合满; 赵世伟

    2011-01-01

    Soil organic carbon, soil active organic carbon, soil alkali-hydrolysable nitrogen, soil available phosphorus, soil available potassium, soil water content and soil bulk density were determined to study the distribution of soil organic carbon and soil physical and chemical properties on degraded alpine meadows in Dangxiong,Tibet. Results showed that the change orders of soil organic carbon content and its density both in the 0-10 cm and 10-20 cm soil layers were normal meadow〉slightiy degraded meadow〉serious degraded meadow; soil organic carbon content and its density in the 0-10 cm soil layer were higher than those in the 10-20 cm soil layer. There were correlations between soil organic carbon and other soil nutrients. The regression analysis showed that there were significantly positive linear relationships between soil organic carbon and soil active organic carbon (y-0. 074 3x-0. 026 1, R^2=0. 913 9), soil alkali-hydrolysable nitrogen (y=2. 676 8 x-F14. 425 O, Rz =0. 977 1), soil available P (y=0. 245 9x+3. 347 9, R2- 0. 931 4), soil available K (y=4. 296 5x-F71. 667 0, RZ=O. 665 3) and soil water content (y-=0. 790 8x -F 5. 424 5, R^A2-0. 715 6),respectively. A significant negative linear correlation existed between soil organic carbon and soil bulk density (y=--0. 016 7x+l. 553 1, RZ=0. 773 5). The loss of soil organic carbon re- sulted in reduction of soil nutrients and moisture and increasing soil bulk density. Path analysis indicated that the change of soil organic carbon had the most significant effect on the soil alkali-hydrolysable nitrogen.%本研究对西藏当雄不同退化程度高寒草甸土壤有机碳分布特征及其与土壤理化性质演变进行分析,结果表明,土壤有机碳及有机碳密度均为正常草甸土壤〉轻度退化草甸土壤〉严重退化草甸土壤,且0~10cm土层中有机碳含量及其密度均高于10~20cm土层土壤。回归分析表明,土壤有机碳与土壤活

  8. Characterization and characteristics of degradable polymer sacks

    International Nuclear Information System (INIS)

    This paper reviews the categories and characteristics of degradable polymers used to manufacture sacks for the collection and subsequent treatment of organic wastes from householders. The characteristics of polyethylene (PE) and starch-based sacks were examined using a number of different methods, including scanning electron microscopy (SEM), chemical analysis and mechanical strength testing of the sacks during their use. The analyses revealed that the characteristics of the PE and starch-based sacks were very different. Photomicrographs indicated that the surface of the PE sack was much smoother than the surface of the starch-based sacks. Polyethylene sacks exhibited a greater mechanical strength, both in the unused state and over time during householder use. The severe loss of mechanical strength during use of the starch-based sacks indicated that only thicker gauge sacks were suitable for the fortnightly kerbside collection of biodegradable municipal waste (BMW). Chemical analysis of two different PE sacks indicated that transition metals and other elements were commonly incorporated into the PE structure in order to facilitate increased polymer degradation

  9. Soil quality degradation processes along a deforestation chronosequence in the Ziwuling Area, China

    Science.gov (United States)

    Accelerated erosion caused by deforestation and soil degradation has become the primary factor limiting sustainable utilization of soil resources on the Loess Plateau of Northwestern China. We studied the physical, chemical, and microbiological processes of soil degradation along a chronosequence o...

  10. Transport and degradation of propylene glycol in the vadose zone: model development and sensitivity analysis

    NARCIS (Netherlands)

    Schotanus, D.; Meeussen, J.C.L.; Lissner, H.; Ploeg, van der M.J.; Wehrer, M.; Totsche, K.U.; Zee, van der S.E.A.T.M.

    2014-01-01

    Transport and degradation of de-icing chemical (containing propylene glycol, PG) in the vadose zone were studied with a lysimeter experiment and a model, in which transient water flow, kinetic degradation of PG and soil chemistry were combined. The lysimeter experiment indicated that aerobic as well

  11. Chemical Leukoderma.

    Science.gov (United States)

    Bonamonte, Domenico; Vestita, Michelangelo; Romita, Paolo; Filoni, Angela; Foti, Caterina; Angelini, Gianni

    2016-01-01

    Chemical leukoderma, often clinically mimicking idiopathic vitiligo and other congenital and acquired hypopigmentation, is an acquired form of cutaneous pigment loss caused by exposure to a variety of chemicals that act through selective melanocytotoxicity. Most of these chemicals are phenols and aromatic or aliphatic catechols derivatives. These chemicals, however, are harmful for melanocytes in individuals with an individual susceptibility. Nowadays, chemical leukoderma is fairly common, caused by common domestic products. The presence of numerous acquired confetti- or pea-sized macules is clinically characteristic of chemical leukoderma, albeit not diagnostic. Other relevant diagnostic elements are a history of repeated exposure to a known or suspected depigmenting agent at the sites of onset and a macules distribution corresponding to sites of chemical exposure. Spontaneous repigmentation has been reported when the causative agent is avoided; the repigmentation process is perifollicular and gradual, taking place for a variable period of weeks to months. PMID:27172302

  12. Composição química, digestibilidade e cinética de degradação ruminal das silagens de híbridos de girassol em diferentes épocas de semeadura Effects of sowing dates on chemical composition, digestibility and ruminal degradation kinetics of silages from sunflower hybrids

    Directory of Open Access Journals (Sweden)

    Renius Mello

    2006-08-01

    Full Text Available Objetivou-se estimar o valor nutritivo das silagens de quatro híbridos de girassol - Rumbosol-91 (forrageiro, M-734 (duplo-propósito, C-11 (duplo-propósito e BRS-191 (granífero - semeados em três épocas: outubro (antecipada, novembro (normal e dezembro (tardia - por meio de análises químicas, da digestibilidade e da cinética de degradação ruminal. O delineamento experimental foi em blocos ao acaso, com arranjo fatorial 4 x 3 (quatro híbridos x três épocas de semeadura e três repetições. Os teores de MS variaram de 23,2 a 43,0%; o pH, de 4,0 a 5,1; e o N-NH3%/NT, de 5,3 a 16,8%. Os teores de CZ oscilaram de 6,8 a 8,8% e aumentaram da semeadura em outubro para dezembro. O Rumbosol-91 apresentou teores menores de EE e maiores de N na parede celular, de N indisponível e de carboidratos totais (CHOT. Os teores de PB aumentaram e os de CHOT diminuíram de outubro para dezembro. A semeadura de novembro e o C-11 apresentaram menores teores de FDN, FDNcp e FDA. O C-11 semeado em novembro apresentou menor teor de LDA. A semeadura de outubro e o Rumbosol-91 tiveram maior proporção de LDA%/FDN. O Rumbosol-91 apresentou maior DIVMS e DIVFDN. A semeadura de novembro e os híbridos C-11 e M-734 apresentaram maior teor de NDT. O desaparecimento da MS pode ser representado por um único perfil de degradação. A proporção de FDN indegradável (I aumentou da semeadura em outubro para dezembro, com maiores valores para o BRS-191 semeado em dezembro. A extensão (Vf1 e a taxa (k1 de degradação da fração solúvel de rápida digestão diminuíram da semeadura em outubro para dezembro, com maiores valores para o Rumbosol-91 semeado em outubro. A relação entre análise química, digestibilidade, NDT e cinética de degradação ruminal foi melhor para os híbridos M-734 e C-11 semeados em novembro.The objective of this trial was to estimate chemical composition, digestibility and ruminal degradation kinetics of silages from four sunflower

  13. ASSAYING OF AUTOPHAGIC PROTEIN DEGRADATION

    NARCIS (Netherlands)

    C. Bauvy; A.J. Meijer; P. Codogno

    2009-01-01

    Macroautophagy is a three-step process: (1) autophagosomes form and mature, (2) the autophagosomes fuse with lysosomes, and (3) the autophagic cargo is degraded in the lysosomes. It is this lysosomal degradation of the autophagic cargo that constitutes the autophagic flux. As in the case of metaboli

  14. Degradation of carbofuran by ozonation.

    Science.gov (United States)

    Suneethi, S; Joseph, Kurian

    2009-04-01

    Degradation of commercial grade carbofuran (2, 3 dihydro-2, 2-dimethyl-7 benzo furanyl-N-methyl carbamate) in aqueous solution by ozone oxidation was investigated using bench scale experiments. The degradation rate was strongly influenced by the ozone dosage, pH, initial concentration of carbofuran and contact time of ozonation. Carbofuran solution of 200ppm concentration was degraded by 79% within 10 minutes consuming 87 mg of ozone at pH 4. The associated TOC reduction was observed to be 53%. Ammonium (20 mg/L) and nitrate (30 mg/L) ions were detected in the effluent as degradation products of ozonation. The results support the effectiveness of ozonation for degradation of organic pesticides such as carbofuran.

  15. EFECTO DE LA APLICACIÓN DE BIOSOLIDOS EN EL CRECIMIENTO DE Jacaranda mimosifolia (Gualanday Y EN LAS CONDICIONES FÍSICAS Y QUÍMICAS DE UN SUELO DEGRADADO EFFECT OF BIOSOLIDS APPLICATION ON THE GROWTH OF Jacaranda mimosifolia (Gualanday AND UNDER PHYSICAL AND CHEMICAL CONDITIONS OF A DEGRADED SOIL

    Directory of Open Access Journals (Sweden)

    Ramiro Ramirez Pisco

    2007-06-01

    estabilidad de agregados y la retención de humedad, y disminuyéndose la densidad aparente y densidad real.The biosolids are organic materials, derived from wastewater treatment of domestic and industrial sewage. One of the main problems of wastewater treatment plants is the final destination of the biosolids. Their deposit in sanitary fillers, the incineration and land application are the main methods of dispose; the first two methods are expensive, while the last one, is gaining acceptance, because the biosolids are a resource that can be used as supplementary organic fertilizer. Furthermore, land application of biosolids can help to improve declined soil fertility in degraded soils, but it can be generated contamination problems. The aims of this study were to investigate the effect of biosolids application on the growth of Jacaranda mimosifolia (Gualanday and the changes on physical and chemical conditions of a degraded soil. This arboreal specie was planted in a degraded soil amended with biosolids, and was grown in a greenhouse. The treatments corresponded to contents of organic matter in the mixture (soil-biosolid of 0 %, 2 %, 4 % and 8 %, in a completely randomized design with four treatments and ten replications. Monthly samplings were realized to get information about the variables: survival, height and diameter of stem, and number of leaves. The dry biomass was evaluated at the end of the study. The physical and chemical analyses were made at the beginning of the experiment and three months later. The chemical analyses included pH, oxidable organic carbon, Al, Ca, Mg, K, CICE, Fe, Mn, Cu, Zn, P, S, B, NO3-, NH4+, and the physical analyses included aggregate stability, bulk density, real density and water retention. The statistical analysis between treatments was realized every month, by analysis of variance and Duncan's multiple range test, using a 95 % confidence level. The treatment with a 2 % of organic matter was not affected the plant growth and was similar

  16. 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) cometabolically with 0.2% yeast extract (w/v) in 48 hours when starting at 0.4 OD 600nm. After establishing this stable degradation capability, variations were tested to explore the wider parameters of BT activity in temperature, pH, intermediate degradation, co-metabolic dependence, and transfer stability. Due to the vast differences in temperature at various points in the refineries, a wide range of temperatures were assessed. The results indicate that BT retains the ability to degrade HA, a model surrogate for tailings pond contaminants, at temperatures ranging from 15°C to 35°C. Hexanamide (HAM) was shown to be an intermediate generated during the degradation of HA in an earlier work and HAM is completely degraded after 48 hours, indicating that HAM is not the final product of HA degradation. Various replacements for yeast extract were attempted. Glucose, a carbon source; casein amino acids, a protein source; additional ammonia, mimicking known media; and additional phosphate with Wolffe’s vitamins and minerals all showed no significant degradation of HA compared to control. Decreasing the yeast extract concentration (0.05%) demonstrated limited but significant degradation. Finally, serial inoculations of BT were performed to determine the stability of degradation

  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. Chemical networks*

    OpenAIRE

    Thi Wing-Fai

    2015-01-01

    This chapter discusses the fundamental ideas of how chemical networks are build, their strengths and limitations. The chemical reactions that occur in disks combine the cold phase reactions used to model cold molecular clouds with the hot chemistry applied to planetary atmosphere models. With a general understanding of the different types of reactions that can occur, one can proceed in building a network of chemical reactions and use it to explain the abundance of species seen in disks. One o...

  19. Air pollutants degrade floral scents and increase insect foraging times

    Science.gov (United States)

    Fuentes, Jose D.; Chamecki, Marcelo; Roulston, T.'ai; Chen, Bicheng; Pratt, Kenneth R.

    2016-09-01

    Flowers emit mixtures of scents that mediate plant-insect interactions such as attracting insect pollinators. Because of their volatile nature, however, floral scents readily react with ozone, nitrate radical, and hydroxyl radical. The result of such reactions is the degradation and the chemical modification of scent plumes downwind of floral sources. Large Eddy Simulations (LES) are developed to investigate dispersion and chemical degradation and modification of floral scents due to reactions with ozone, hydroxyl radical, and nitrate radical within the atmospheric surface layer. Impacts on foraging insects are investigated by utilizing a random walk model to simulate insect search behavior. Results indicate that even moderate air pollutant levels (e.g., ozone mixing ratios greater than 60 parts per billion on a per volume basis, ppbv) substantially degrade floral volatiles and alter the chemical composition of released floral scents. As a result, insect success rates of locating plumes of floral scents were reduced and foraging times increased in polluted air masses due to considerable degradation and changes in the composition of floral scents. Results also indicate that plant-pollinator interactions could be sensitive to changes in floral scent composition, especially if insects are unable to adapt to the modified scentscape. The increase in foraging time could have severe cascading and pernicious impacts on the fitness of foraging insects by reducing the time devoted to other necessary tasks.

  20. Performance degradation, polymer encapsulant degradation, and estimating lifetimes for photovoltaic modules from accelerated testing

    Energy Technology Data Exchange (ETDEWEB)

    Czanderna, A.W.; Pern, F.J. [National Renewable Energy Lab., Golden, CO (United States)

    1996-12-31

    The purposes of this paper are to provide background information about encapsulants for photovoltaic (PV) modules and to evaluate estimates of the durability of different materials used in PV modules. The authors summarize the field-deployed module degradation in performance, the established degradation mechanisms of ethylene vinyl acetate (EVA) copolymer, and potential degradation mechanisms in other module components and at materials interfaces. Most of the emphasis is on estimates for the commercially used EVA formulations A9918 and 15295. These formulations have degraded in field-deployed modules to produce acetic acid and a yellow to brown color from polyenes and the module efficiencies have been reduced by 10% to 70% in 4 to 12 years. Yet, projections were made by several different research groups in the 1980s that the EVA lifetime could range from 20 to 100 years, the production of acetic acid would only be 0.006% in 20 years, and that silver metallization would survive attack from acetic acid for 300 years at 55 C. Those authors did not use appropriate variables or specimen configurations that simulate reality, and based their projections using the generalization that chemical reaction rates double for every 10 C increase in T. The authors review the inherent errors in their assumptions about the Arrhenius relation. They also show how degradation in efficiency (from current-voltage data) comparable to field experience is obtained using minimodules with a construction that simulates reality and by using appropriate variables in accelerated testing, i.e., UV, T, and RH. A test protocol is outlined that simulates reality and permits making suitable service lifetime projections.

  1. UV/TiO2 photocatalytic degradation of xanthene dyes

    OpenAIRE

    Pereira, Luciana; Pereira, Raquel; Oliveira, Catarina S.; Apostol, Laura; GAVRILESCU, M.; M. N. Pons; O. Zahraa; Alves, M. M.

    2013-01-01

    UV/titanium dioxide (TiO2) degradation of two xanthene dyes, erythrosine B (Ery) and eosin Y (Eos), was studied in a photocatalytic reactor. Photocatalysis was able to degrade 98% of Ery and 73% of Eos and led to 65% of chemical oxygen demand removal. Experiments in buffered solutions at different initial pH values reveal the pH dependence of the process, with better results obtained under acidic conditions due to the electrostatic attraction caused by the opposite cha...

  2. A comprehensive review of the process on hexachlorobenzene degradation

    Directory of Open Access Journals (Sweden)

    Ji Xiyan

    2015-01-01

    Full Text Available This paper describes the chemical, physical property of the pollution source along with its perniciousness. In addition, with the recent treatment or degradation of the hexachlorobenzene (HCB, it talks about the research developments on the HCB. Of the many options available for treatment of municipal and industrial HCB pollution, the anaerobic biological treatment process is unique because of its potential for producing usable energy. It focuses on the biodegradation pathway which is intent to finish the steps of dechlorination. Moreover, the future study on the HCB degradation is prospected in this paper from the author’s angle.

  3. Physiology, biochemistry and possible applications of microbial caffeine degradation.

    Science.gov (United States)

    Gummadi, Sathyanarayana N; Bhavya, B; Ashok, Nandhini

    2012-01-01

    Caffeine, a purine alkaloid is a constituent of widely consumed beverages. The scientific evidence which has proved the harm of this alkaloid has paved the way for innumerable research in the area of caffeine degradation. In addition to this, the fact that the by-products of the coffee and tea industry pollute the environment has called for the need of decaffeinating coffee and tea industry's by-products. Though physical and chemical methods for decaffeination are available, the lack of specificity for removal of caffeine in these techniques and their non-eco-friendly nature has opened the area of microbial and enzymatic degradation of caffeine. Another important application of microbial caffeine degradation apart from its advantages like specificity, eco-friendliness and cost-effectiveness is the fact that this process will enable the production of industrially and medically useful components of the caffeine degradation pathway like theobromine and theophylline. This is a comprehensive review which mainly focuses on caffeine degradation, large-scale degradation of the same and its applications in the industrial world.

  4. Degradation of Dye Wastewater by ns-Pulse DBD Plasma

    Science.gov (United States)

    Gao, Jin; Gu, Pingdao; Yuan, Li; Zhong, Fangchuan

    2013-09-01

    Two plasma reactors have been developed and used to degrade dye wastewater agents. The configuration of one plasma reactor is a comb-like extendable unit module consisting of 5 electrodes covered with a quartz tube and the other one is an array reactor which is extended from the unit module. The decomposition of wastewater by ns pulse dielectric barrier discharge (DBD) plasma have been carried out by atomizing the dyeing solutions into the reactors. During experiments, the indigo carmine has been treated as the waste agent. The measurements of UV-VIS absorption spectroscopy and the chemical oxygen demand (COD) are carried out to demonstrate the decomposition effect on the wastewater. It shows that the decoloration rate of 99% and the COD degradation rate of 65% are achieved with 15 min treatment in the unit reactor. The effect of electrical parameters on degradation has been studied in detail. Results from the array reactor indicate that it has a better degradation effect than the unit one. It can not only totally remove the chromogenic bond of the indigo carmine solution, but also effectively degrade unsaturated bonds. The decoloration rate reaches 99% after 10 min treatment, the decomposition rate of the unsaturated bond reaches 83% after 60 min treatment, and the COD degradation rate is nearly 74%.

  5. Polysaccharide degradation systems of the saprophytic bacterium Cellvibrio japonicus.

    Science.gov (United States)

    Gardner, Jeffrey G

    2016-07-01

    Study of recalcitrant polysaccharide degradation by bacterial systems is critical for understanding biological processes such as global carbon cycling, nutritional contributions of the human gut microbiome, and the production of renewable fuels and chemicals. One bacterium that has a robust ability to degrade polysaccharides is the Gram-negative saprophyte Cellvibrio japonicus. A bacterium with a circuitous history, C. japonicus underwent several taxonomy changes from an initially described Pseudomonas sp. Most of the enzymes described in the pre-genomics era have also been renamed. This review aims to consolidate the biochemical, structural, and genetic data published on C. japonicus and its remarkable ability to degrade cellulose, xylan, and pectin substrates. Initially, C. japonicus carbohydrate-active enzymes were studied biochemically and structurally for their novel polysaccharide binding and degradation characteristics, while more recent systems biology approaches have begun to unravel the complex regulation required for lignocellulose degradation in an environmental context. Also included is a discussion for the future of C. japonicus as a model system, with emphasis on current areas unexplored in terms of polysaccharide degradation and emerging directions for C. japonicus in both environmental and biotechnological applications. PMID:27263016

  6. Radiolytic degradation of malathion and lindane in aqueous solutions

    International Nuclear Information System (INIS)

    Degradation of malathion and lindane pesticides present in an aqueous solution was investigated on a laboratory scale upon gamma-irradiation from a 60Co source. The effects of pesticide group, presence of various additives and absorbed dose on efficiency of pesticide degradation were investigated. Gamma-irradiation was carried out in distilled water solutions (malathion and lindane) and in combination with humic solution (HS), nitrous oxide (N2O) and HS/N2O (lindane) over the range 0.1-2 kGy (malathion) and 5-30 kGy (lindane). Malathion was easily degraded at low absorbed doses compared to lindane in distilled water solutions. Absorbed doses required to remove 50% and 90% of initial malathion and lindane concentrations in distilled water solutions were 0.53 and 1.77 kGy (malathion) and 17.97 and 28.79 kGy (lindane), respectively. The presence of HS, N2O and HS/N2O additives in aqueous solutions, significantly improved the effectiveness of radiolytic degradation of lindane. Chemical analysis of the pesticides and the by-products resulted from the radiolytic degradation were made using a gas chromatography associated with mass spectrometry (GC-MS). Additionally, the final degradation products of irradiation as detected by ion chromatography (IC) were acetic acid and traces of some anions (phosphate and chloride).

  7. Performance Degradation of LSCF Cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Alinger, Matthew

    2013-09-30

    This final report summarizes the progress made during the October 1, 2008 - September 30, 2013 period under Cooperative Agreement DE-NT0004109 for the U. S. Department of Energy/National Energy Technology Laboratory (USDOE/NETL) entitled “Performance Degradation of LSCF Cathodes”. The primary objective of this program is to develop a performance degradation mitigation path for high performing, cost-effective solid oxide fuel cells (SOFCs). Strategies to mitigate performance degradation are developed and implemented. In addition, thermal spray manufacturing of SOFCs is explored. Combined, this work establishes a basis for cost-effective SOFC cells.

  8. Agricultural utilization of sewage sludge: effect on the chemical and physical properties of soils and on the productivity and recovery of degraded areas/ Uso agrícola do lodo de esgoto: influência nas propriedades químicas e físicas do solo, produtividade e recuperação de áreas degradadas

    Directory of Open Access Journals (Sweden)

    João Tavares Filho

    2006-07-01

    Full Text Available This study is an overview of the agricultural recycling of sewage sludge and its impact on the chemical and physical properties of soils and on the productivity and recovery of degraded areas. Sewage sludge contains some of the essential plant nutrients (nitrogen, phosphorous, and micronutrients; it also has variable humidity content and is rich in organic matter. Sewage sludge also acts as a soil conditioner, improving soil structure and aggregation, thus decreasing density and increasing aeration of soils.Sewage sludge can complement other crop fertilization techniques by reducing the use of chemical fertilizers and fertilization costs as it increases nutrient availability in soils. As a result, the sludge can enhance plant development and productivity. Sludge application in degraded areas leads to a rapid growth of gramineous and leguminous plants. Plants growing in sludge-applied areas tend to be more vigorous and to cover larger areas (percentage; they also tend to have higher productivity and a better development of the root system. Soil recovery by liming and mineral fertilization can also lead to vegetation regrowth; however, the poor physical and biological soil conditions can deteriorate the cover plants before the soil is actually recovered. Sewage sludge must be processed before being used and cannot be applied directly to agricultural or forested land until biological treatments reduce the sludge organic content and promote organic matter stabilization. In the State of Paraná, Brazil, the direct application of sewage sludge on horticultural and other products that are ingested raw, is not recommended. Sludge fertilization is recommended for corn, wheat, sugarcane, sorghum, fruitiferous plants, and for forest plant species used to recover degraded areas. State regulations determine the levels of heavy metals allowed in the sludge and the maximum dosage of 50 ton biosolid matter/ha, for a 10-year period.Objetivou-se com esta revis

  9. Microcantilever sensors for fast analysis of enzymatic degradation of poly (D, L-lactide)

    DEFF Research Database (Denmark)

    Bose, Sanjukta; Keller, Stephan Sylvest; Boisen, Anja;

    2015-01-01

    In this work we have performed a detailed analysis of enzymatic degradation of amorphous poly (d, l-lactide) (PDLLA) by measuring the resonance frequencies of polymer coated microcantilevers before and after degradation. The miniaturized cantilever system provides a fast analysis...... of the biodegradation rate of PDLLA with a minute amount of sample and without the need of thermal and chemical acceleration. The degradation rate of the polymer has been estimated by multilayer cantilever theory and model simulation. A bulk degradation rate of 0.24 μg mm-2 hour-1 is estimated which agrees well...

  10. Chemical sensors

    Science.gov (United States)

    Lowell, J.R. Jr.; Edlund, D.J.; Friesen, D.T.; Rayfield, G.W.

    1991-07-02

    Sensors responsive to small changes in the concentration of chemical species are disclosed. The sensors comprise a mechanochemically responsive polymeric film capable of expansion or contraction in response to a change in its chemical environment. They are operatively coupled to a transducer capable of directly converting the expansion or contraction to a measurable electrical response. 9 figures.

  11. Degradation Of Cementitious Materials Associated With Saltstone Disposal Units

    Energy Technology Data Exchange (ETDEWEB)

    Flach, G. P; Smith, F. G. III

    2013-03-19

    The Saltstone facilities at the DOE Savannah River Site (SRS) stabilize and dispose of low-level radioactive salt solution originating from liquid waste storage tanks at the site. The Saltstone Production Facility (SPF) receives treated salt solution and mixes the aqueous waste with dry cement, blast furnace slag, and fly ash to form a grout slurry which is mechanically pumped into concrete disposal cells that compose the Saltstone Disposal Facility (SDF). The solidified grout is termed “saltstone”. Cementitious materials play a prominent role in the design and long-term performance of the SDF. The saltstone grout exhibits low permeability and diffusivity, and thus represents a physical barrier to waste release. The waste form is also reducing, which creates a chemical barrier to waste release for certain key radionuclides, notably Tc-99. Similarly, the concrete shell of an SDF disposal unit (SDU) represents an additional physical and chemical barrier to radionuclide release to the environment. Together the waste form and the SDU compose a robust containment structure at the time of facility closure. However, the physical and chemical state of cementitious materials will evolve over time through a variety of phenomena, leading to degraded barrier performance over Performance Assessment (PA) timescales of thousands to tens of thousands of years. Previous studies of cementitious material degradation in the context of low-level waste disposal have identified sulfate attack, carbonation influenced steel corrosion, and decalcification (primary constituent leaching) as the primary chemical degradation phenomena of most relevance to SRS exposure conditions. In this study, degradation time scales for each of these three degradation phenomena are estimated for saltstone and concrete associated with each SDU type under conservative, nominal, and best estimate assumptions. The nominal value (NV) is an intermediate result that is more probable than the conservative

  12. Chemical Radioprotectors

    Directory of Open Access Journals (Sweden)

    S. N. Upadhyay

    2005-10-01

    Full Text Available Protection of biological systems against radiation damage is of paramount importance during accidental and unavoidable exposure to radiation. Several physico-chemical and biological factors collectively contribute to the damage caused by radiation and are, therefore, targets for developing radioprotectors. Work on the development of chemicals capable of protecting biological systemsfrom radiation damage was initiated nearly six decades ago with cysteine being the first molecule to be reported. Chemicals capable of scavenging free radicals, inducing oxygen depletion,antioxidants and modulators of immune response have been some of the radioprotectors extensively investigated with limited success. Mechanism of action of some chemical radioprotectors and their combinations have been elucidated, while further understanding is required in many instances. The present review elaborates on structure-activity relationship of some of the chemical radioprotectors, their evaluation, and assessment, limitation, and future prospects.

  13. Resorbable composites with bioresorbable glass fibers for load-bearing applications. In vitro degradation and degradation mechanism.

    Science.gov (United States)

    Lehtonen, Timo J; Tuominen, Jukka U; Hiekkanen, Elina

    2013-01-01

    An in vitro degradation study of three bioresorbable glass fiber-reinforced poly(l-lactide-co-dl-lactide) (PLDLA) composites was carried out in simulated body fluid (SBF), to simulate body conditions, and deionized water, to evaluate the nature of the degradation products. The changes in mechanical and chemical properties were systematically characterized over 52 weeks dissolution time to determine the degradation mechanism and investigate strength retention by the bioresorbable glass fiber-reinforced PLDLA composite. The degradation mechanism was found to be a combination of surface and bulk erosion and does not follow the typical core-accelerated degradation mechanism of poly(α-hydroxyacids). Strength retention by bioresorbable glass fiber-reinforced PLDLA composites can be tailored by changing the oxide composition of the glass fibers, but the structure-property relationship of the glass fibers has to be understood and controlled so that the phenomenon of ion leaching can be utilized to control the degradation rate. Therefore, these high performance composites are likely to open up several new possibilities for utilizing resorbable materials in clinical applications which could not be realized in the past. PMID:22963847

  14. Ordered bulk degradation via autophagy

    DEFF Research Database (Denmark)

    Dengjel, Jörn; Kristensen, Anders Riis; Andersen, Jens S

    2008-01-01

    During amino acid starvation, cells undergo macroautophagy which is regarded as an unspecific bulk degradation process. Lately, more and more organelle-specific autophagy subtypes such as reticulophagy, mitophagy and ribophagy have been described and it could be shown, depending on the experimental...... setup, that autophagy specifically can remove certain subcellular components. We used an unbiased quantitative proteomics approach relying on stable isotope labeling by amino acids in cell culture (SILAC) to study global protein dynamics during amino acid starvation-induced autophagy. Looking...... at proteasomal and lysosomal degradation ample cross-talk between the two degradation pathways became evident. Degradation via autophagy appeared to be ordered and regulated at the protein complex/organelle level. This raises several important questions such as: can macroautophagy itself be specific and what...

  15. Chitin Degradation In Marine Bacteria

    DEFF Research Database (Denmark)

    Paulsen, Sara; Machado, Henrique; Gram, Lone

    2015-01-01

    Introduction: Chitin is the most abundant polymer in the marine environment and the second most abundant in nature. Chitin does not accumulate on the ocean floor, because of microbial breakdown. Chitin degrading bacteria could have potential in the utilization of chitin as a renewable carbon...... and nitrogen source in the fermentation industry.Methods: Here, whole genome sequenced marine bacteria were screened for chitin degradation using phenotypic and in silico analyses.Results: The in silico analyses revealed the presence of three to nine chitinases in each strain, however the number of chitinases...... chitin regulatory system.Conclusions: This study has provided insight into the ecology of chitin degradation in marine bacteria. It also served as a basis for choosing a more efficient chitin degrading production strain e.g. for the use of chitin waste for large-scale fermentations....

  16. Bacterial isolates degrading aliphatic polycarbonates.

    Science.gov (United States)

    Suyama, T; Hosoya, H; Tokiwa, Y

    1998-04-15

    Bacteria that degrade an aliphatic polycarbonate, poly(hexamethylene carbonate), were isolated from river water in Ibaraki. Prefecture, Japan, after enrichment in liquid medium containing poly(hexamethylene carbonate) suspensions as carbon source, and dilution to single cells. Four of the strains, 35L, WFF52, 61A and 61B2, degraded poly(hexamethylene carbonate) on agar plate containing suspended poly(hexamethylene carbonate). Degradation of poly(hexamethylene carbonate) was confirmed by gel permeation chromatography. Besides poly(hexamethylene carbonate), the strains were found to degrade poly(tetramethylene carbonate). The strains were characterized morphologically, physiologically, and by 16S rDNA sequence analysis. Strains 35L and WFF52 were tentatively identified as Pseudomonas sp. and Variovorax sp., respectively, while strains 61A and 61B2 constitute an unidentified branch within the beta subclass of the Proteobacteria.

  17. FTIR study of degradation products of aliphatic polyesters carbon fibres composites

    Science.gov (United States)

    Pamuła, Elżbieta; Błażewicz, Marta; Paluszkiewicz, Czesława; Dobrzyński, Piotr

    2001-09-01

    Biodegradable polymer composites based on polylactides and polyglycolides constitute a group of materials characterised by good biocompatibility. They are considered in tissue engineering as scaffolds for cells proliferation and controlled tissue regeneration. Two types of biodegradable polymers possessing different chemical structure, molecular weights and crystallinity degrees and two composite materials made up of them and carbon fibres were analysed in this study. The samples were incubated in aqueous media for 8 weeks and analysed by means of Fourier transform infrared spectroscopy in the attenuated total reflection mode (FTIR-ATR). Infrared spectroscopy enabled identification of degradation products and estimation of the influence of carbon fibres on hydrolytic degradation of analysed polymers. Analysis of the infrared spectra showed that hydrolytic degradation process depends on chemical structure, molecular weight and crystallinity of polymers. Catalytic effect of carbon fibres at the initial stage of polymer degradation was observed. Further degradation is dependent on the properties of polymer.

  18. Degradation monitoring using probabilistic inference

    Science.gov (United States)

    Alpay, Bulent

    In order to increase safety and improve economy and performance in a nuclear power plant (NPP), the source and extent of component degradations should be identified before failures and breakdowns occur. It is also crucial for the next generation of NPPs, which are designed to have a long core life and high fuel burnup to have a degradation monitoring system in order to keep the reactor in a safe state, to meet the designed reactor core lifetime and to optimize the scheduled maintenance. Model-based methods are based on determining the inconsistencies between the actual and expected behavior of the plant, and use these inconsistencies for detection and diagnostics of degradations. By defining degradation as a random abrupt change from the nominal to a constant degraded state of a component, we employed nonlinear filtering techniques based on state/parameter estimation. We utilized a Bayesian recursive estimation formulation in the sequential probabilistic inference framework and constructed a hidden Markov model to represent a general physical system. By addressing the problem of a filter's inability to estimate an abrupt change, which is called the oblivious filter problem in nonlinear extensions of Kalman filtering, and the sample impoverishment problem in particle filtering, we developed techniques to modify filtering algorithms by utilizing additional data sources to improve the filter's response to this problem. We utilized a reliability degradation database that can be constructed from plant specific operational experience and test and maintenance reports to generate proposal densities for probable degradation modes. These are used in a multiple hypothesis testing algorithm. We then test samples drawn from these proposal densities with the particle filtering estimates based on the Bayesian recursive estimation formulation with the Metropolis Hastings algorithm, which is a well-known Markov chain Monte Carlo method (MCMC). This multiple hypothesis testing

  19. Some Misconceptions About Plastic Degradation

    OpenAIRE

    Raouf, Mohamed Imad N. Raouf

    1999-01-01

    In consistence with the importance of implementing best utilization of human resources towards maintaining suitable healthy environment for our next generations, concepts and fundamentals upon which most researches on degradation of plastics are based, as a solution of solid waste reduction, will be discussed. Proper understanding of plastic figures would better utilize human efforts toward useful tasks to control solid waste. Unfortunately, when plastics are made more degradable, they becom...

  20. Sonolytic degradation of 2-chlorobiphenyl

    Institute of Scientific and Technical Information of China (English)

    张光明; 华天星; 常爱敏

    2004-01-01

    The sonolytic degradation of 2-chlorobiphenyl was investigated. Mass spectroscopy was used to detect the products of sonolytic degradation of 2-chlorobiphenyl. The results show that the products of sonolytic degradation, such as biphenyl, ethyl benzene, diethylbiphenyl, dibutylbiphenyl, phenol, propylphenol and di-tert-butyl phenol are produced by thermolysis and hydroxyl free radical reactions, in which biphenyl counts for almost 40%(mole fraction) of the mother compound and others are at trace level. Rapid accumulation of chloride ion shows quick dechlorination, and 78% organic chlorine is converted into chloride ion. Free radical scavengers, bicarbonate and carbonate, decrease the reaction rate of sonolytic degradation of 2-chlorobiphenyl significantly, and the pseudo 1st order rate constant of sonolytic degradation of 2-chlorobiphenyl decreases linearly with the natural logarithm of the concentration of the added free radical scavenger, showing that the pyrolysis and hydroxyl free radical reaction are the two major pathways for the sonolytic degradation of 2-chlorobiphenyl, in which the hydroxyl radical concentration is estimated to be 1 × 10 10mol/L.

  1. Hazardous Chemicals

    Centers for Disease Control (CDC) Podcasts

    2007-04-10

    Chemicals are a part of our daily lives, providing many products and modern conveniences. With more than three decades of experience, The Centers for Disease Control and Prevention (CDC) has been in the forefront of efforts to protect and assess people's exposure to environmental and hazardous chemicals. This report provides information about hazardous chemicals and useful tips on how to protect you and your family from harmful exposure.  Created: 4/10/2007 by CDC National Center for Environmental Health.   Date Released: 4/13/2007.

  2. Redox regulation of insulin degradation by insulin-degrading enzyme.

    Directory of Open Access Journals (Sweden)

    Crystal M Cordes

    Full Text Available Insulin-degrading enzyme (IDE is a thiol sensitive peptidase that degrades insulin and amyloid β, and has been linked to type 2 diabetes mellitus and Alzheimer's disease. We examined the thiol sensitivity of IDE using S-nitrosoglutathione, reduced glutathione, and oxidized glutathione to distinguish the effects of nitric oxide from that of the redox state. The in vitro activity of IDE was studied using either partially purified cytosolic enzyme from male Sprague-Dawley rats, or purified rat recombinant enzyme. We confirm that nitric oxide inhibits the degrading activity of IDE, and that it affects proteasome activity through this interaction with IDE, but does not affect the proteasome directly. Oxidized glutathione inhibits IDE through glutathionylation, which was reversible by dithiothreitol but not by ascorbic acid. Reduced glutathione had no effect on IDE, but reacted with partially degraded insulin to disrupt its disulfide bonds and accelerate its breakdown to trichloroacetic acid soluble fragments. Our results demonstrate the sensitivity of insulin degradation by IDE to the redox environment and suggest another mechanism by which the cell's oxidation state may contribute to the development of, and the link between, type 2 diabetes and Alzheimer's disease.

  3. Degradation of Silicone Encapsulants in CPV Optics: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Miller, David C.; Tappan, Ian A.; Cai, Can; Dauskardt, Reinhold H.

    2016-07-01

    High efficiency multijunction solar cells in terrestrial concentrator photovoltaic (CPV) modules are becoming an increasingly cost effective and viable option in utility scale power generation. As with other utility scale photovoltaics, CPV modules need to guarantee operational lifetimes of at least 25 years. The reliability of optical elements in CPV modules poses a unique materials challenge due to the increased UV irradiance and enhanced temperature cycling associated with concentrated solar flux. The polymeric and thin film materials used in the optical elements are especially susceptible to UV damage, diurnal temperature cycling and active chemical species from the environment. We used fracture mechanics approaches to study the degradation modes including: the adhesion between the encapsulant and the cell or secondary optical element; and the cohesion of the encapsulant itself. Understanding the underlying mechanisms of materials degradation under elevated stress conditions is critical for commercialization of CPV technology and can offer unique insights into degradation modes in similar encapsulants used in other photovoltaic modules.

  4. Glow Discharge Induced Hydroxyl Radical Degradation of 2-Naphthylamine

    Science.gov (United States)

    Lu, Quanfang; Yu, Jie; Gao, Jinzhang; Yang, Wu

    2005-06-01

    In an aqueous solution, normal electrolysis at high voltages switches over spontaneously to glow discharge electrolysis and gives rise to hydroxyl radical, hydrogen peroxide, and aqueous electron, as well as several other active species. Hydroxyl radical directly attacks organic contaminants to make them oxidized. In the present paper, 2-naphthylamine is eventually degraded into hydrogen carbonate and carbon dioxide. The degradation process is analyzed by using an Ultraviolet (UV) absorption spectrum, high-performance liquid chromatography (HPLC) and chemical oxygen demand (COD). It is demonstrated that 2-naphthylamine (c0 =30 mg·l-1) is completely converted within 2h at 30°C and 600 V by glow discharge electrolysis, and the degradation is strongly dependent upon the presence of ferrous ions. COD is ascended in the absence of ferrous ions and descended in the presence of them.

  5. Controlling of degradation effects in radiation processing of polymers

    International Nuclear Information System (INIS)

    Radiation induced degradation technology is a new and promising application of ionizing radiation to develop viscose, pulp, paper, food preservation, pharmaceutical production, and natural bioactive agents industries. Controlling the degree of degradation, uniform molecular weight distribution, saving achieved in the chemicals (used in conventional methods) on a cost basis, and environmentally friendly process are the beneficial effects of using radiation technology in these industries. However, for some development countries such technology is not economic. Therefore, a great effort should be done to reduce the cost required for such technologies. One of the principle factors for reducing the cost is achieving the degradation at low irradiation doses. This not only reduces the cost of radiation but also improve the quality of the end use products. The end product of irradiated natural products such as carboxymethylcellulose and chitosan alginate may be used as food additive or benefited in agricultural purposes. (author)

  6. Monitoring automotive oil degradation: analytical tools and onboard sensing technologies.

    Science.gov (United States)

    Mujahid, Adnan; Dickert, Franz L

    2012-09-01

    Engine oil experiences a number of thermal and oxidative phases that yield acidic products in the matrix consequently leading to degradation of the base oil. Generally, oil oxidation is a complex process and difficult to elucidate; however, the degradation pathways can be defined for almost every type of oil because they mainly depend on the mechanical status and operating conditions. The exact time of oil change is nonetheless difficult to predict, but it is of great interest from an economic and ecological point of view. In order to make a quick and accurate decision about oil changes, onboard assessment of oil quality is highly desirable. For this purpose, a variety of physical and chemical sensors have been proposed along with spectroscopic strategies. We present a critical review of all these approaches and of recent developments to analyze the exact lifetime of automotive engine oil. Apart from their potential for degradation monitoring, their limitations and future perspectives have also been investigated.

  7. Factors involved in mechanical fatigue degradation of dental resin composites.

    Science.gov (United States)

    Lohbauer, U; Belli, R; Ferracane, J L

    2013-07-01

    The design of clinical trials allows for limited insights into the fatigue processes occurring in resin composites and the factors involved therein. In vitro studies, in contrast, can fundamentally narrow study interests to focus on particular degradation mechanisms and, to date, represent the major contributors to the state of knowledge on the subject. These studies show that microstructural features are important in determining strength and fracture toughness, whereas fatigue resistance is mainly related to the susceptibility of the matrix and the filler/matrix interface to mechanical and chemical degradation. In this review, we focus on fracture mechanisms occurring during fatigue, on the methods used to assess them, and on additional phenomena involved in the degradation of initial mechanical properties of resin composites.

  8. Monitoring automotive oil degradation: analytical tools and onboard sensing technologies.

    Science.gov (United States)

    Mujahid, Adnan; Dickert, Franz L

    2012-09-01

    Engine oil experiences a number of thermal and oxidative phases that yield acidic products in the matrix consequently leading to degradation of the base oil. Generally, oil oxidation is a complex process and difficult to elucidate; however, the degradation pathways can be defined for almost every type of oil because they mainly depend on the mechanical status and operating conditions. The exact time of oil change is nonetheless difficult to predict, but it is of great interest from an economic and ecological point of view. In order to make a quick and accurate decision about oil changes, onboard assessment of oil quality is highly desirable. For this purpose, a variety of physical and chemical sensors have been proposed along with spectroscopic strategies. We present a critical review of all these approaches and of recent developments to analyze the exact lifetime of automotive engine oil. Apart from their potential for degradation monitoring, their limitations and future perspectives have also been investigated. PMID:22752447

  9. Degradation of Thiamethoxam in aqueous solution by ozonation: Influencing factors, intermediates, degradation mechanism and toxicity assessment.

    Science.gov (United States)

    Zhao, Qinghua; Ge, Yanan; Zuo, Peng; Shi, Dong; Jia, Shouhua

    2016-03-01

    This paper focuses on the degradation of Thiamethoxam (THIA) in aqueous solution by ozonation. Four influencing factors: pH, THIA initial concentration, ozone concentration and temperature were investigated in order to optimize the conditions, and pH showed the greatest impact; the removal efficiency reached up to 71.19% under the condition of pH 5-11, THIA initial concentration 50-300 mg L(-1), the ozone concentration 10-22.5 mg L(-1) at 293-308 K after 90 min. Four main intermediates were separated and identified and the possible degradation mechanism was proposed. The luminous intensity of photobacteria and the chemical oxygen demand (COD) were measured to assess the changes of toxicity and mineralization in ozonation process, and results showed that the inhibition rate decreased by 60% and 76% of COD was removed after 180 min with the THIA initial concentration was 200 mg L(-1). Our study powerfully demonstrates that the degradation of THIA in aqueous solution by ozonation is a promising technology.

  10. Degradation of methyl bromide in anaerobic sediments

    Science.gov (United States)

    Oremland, R.S.; Miller, L.G.; Strohmaler, F.E.

    1994-01-01

    Methyl bromide (MeBr) was anaerobically degraded in saltmarsh sediments after reaction with sulfide. The product of this nucleophilic substitution reaction was methanethiol, which underwent further chemical and bacterial reactions to form dimethyl sulfide. These two gases appeared transiently during sediment incubations because they were metabolized by methanogenic and sulfate-reducing bacteria. A second, less significant reaction of MeBr was the exchange with chloride, forming methyl chloride, which was also susceptible to attack by sulfide. Incubation of 14C-labeled methyl iodide as an analogue of MeBr resulted in the formation of 14CH4 and 14CO2 and also indicated that sulfate-reducing bacteria as well as methanogens metabolized the methylated sulfur intermediates. These results suggest that exposed sediments with abundant free sulfide, such as coastal salt-marshes, may constitute a sink for atmospheric MeBr.

  11. Coastal environmental degradation in Sri Lanka

    Energy Technology Data Exchange (ETDEWEB)

    Patabendi, P. [Partners for Sustainable Development, Hewagama, Kaduwela (Sri Lanka)

    2000-07-01

    The economic importance of Sri Lanka's coastal area has increased with rapid urbanization and the development of commercial harbours. The growth on this small island has resulted in unmistakable signs of environmental stress which manifests itself in the loss of natural forest cover, water pollution, degradation of rural lands and increased levels of air, water and solid waste pollution. The population is projected to reach 25 million by 2030. This will create an unprecedented demand for food, fibre energy, developable land and other natural resources. Pollution and competition for resources has already degraded about half of the shoreline which put sustainable economic development and environmental values at risk. It is estimated that 25,000 metric tonnes of waste is thrown into the oceanic waters each year. The pollutants include oil, garbage and chemicals from industries. In addition, 60 per cent of the sewage from the city of Colombo is dumped into the sea. Coral mining which supplies 90 per cent of the lime for the construction industry is leading to the destruction of reefs serving as natural barriers against tidal waves. In 1996, the government of Sri Lanka began a plan for coast erosion management in which community participation plays a vital role. A coastal conservation education project for school children is set to begin in the near future. 6 refs., 1 tab.

  12. Photocatalytic degradation of synthetic dye under sunlight

    Directory of Open Access Journals (Sweden)

    Mijin Dušan

    2007-01-01

    Full Text Available Synthetic dyes are widely used in the textile industry. Dye pollutants from the textile industry are an important source of environmental contamination. The majority of these dyes are toxic, mostly non-biodegradable and also resistant to decomposition by physico-chemical methods. Among new oxidation methods or "advanced oxidation processes", heterogeneous photocatalysis appears as an emerging destructive technology leading to the total mineralization of many organic pollutants. CI Basic Yellow 28 (BY28, commonly used as a textile dye, could be photocatalytically degraded using TiU2 as catalyst under sunlight. The effect of some parameters such as the initial catalyst concentration, initial dye concentration, initial NaCl and Na2CO3 concentrations, pH, H2O2 and type of catalyst on the degradation rate of BY28 was examined in details. The presence of NaCl and Na2CO3 led to inhibition of the photodegradation process. The highest photodegradation rate was observed at high pH, while the rate was the lowest at low pH. Increase of the initial H2O2 concentration increased the initial BY28 photodegradation efficiency. ZnO was a better catalyst than TiO2 at low dye concentrations.

  13. Microbial-influenced cement degradation: Literature review

    International Nuclear Information System (INIS)

    The Nuclear Regulatory Commission stipulates that disposed low-level radioactive waste (LLW) be stabilized. Because of apparent ease of use and normal structural integrity, cement has been widely used as a binder to solidify LLW. However, the resulting waste forms are sometimes susceptible to failure due to the actions of waste constituents, stress, and environment. This report reviews literature which addresses the effect of microbiologically influenced chemical attack on cement-solidified LLW. Groups of microorganisms are identified, which are capable of metabolically converting organic and inorganic substrates into organic and mineral acids. Such acids aggressively react with concrete and can ultimately lead to structural failure. Mechanisms inherent in microbial-influenced degradation of cement-based material are the focus of this report. This report provides sufficient evidence of the potential for microbial-influenced deterioration of cement-solidified LLW to justify the enumeration of the conditions necessary to support the microbiological growth and population expansion, as well as the development of appropriate tests necessary to determine the resistance of cement-solidified LLW to microbiological-induced degradation that could impact the stability of the waste form

  14. Photocatalytic degradation of 2,4-dinitrophenol

    International Nuclear Information System (INIS)

    Contamination of the food supply from agricultural waste is an increasing concern worldwide. Numerous hazardous chemicals enter the environment from various industrial sources daily. Many of these pollutants, including 2,4-dinitrophenol (2,4-DNP), are water soluble, toxic, and not easily biodegradable. The solar photocatalytic degradation of 2,4-DNP was investigated in a solution of titanium dioxide (TiO2) that was prepared to be an optically clear aqueous solution of nanosized particles of TiO2. In order to achieve optimal efficiency of the photodegradation, the effects of light intensity and pH were conducted. All experiments were carried out in a batch mode. At a pH of 8, maximum removal of 70% of 2,4-DNP was achieved within 7 h of irradiation time. The nearly homogeneous solution of 5.8 nm TiO2 particles, size determined by XDS, were very effective in the photocatalytic degradation of 2,4-DNP

  15. γ-ray degradation of chitosan to prepare water-soluble oligomers

    International Nuclear Information System (INIS)

    Water-soluble chitosan oligomers with different molecular weight were prepared by a γ-ray degradation method. Effects of irradiation conditions on the chitosan degradation, molecular weight of the irradiated chitosan and yield of the water-soluble products were studied. Gd value of the chitosan radiation degradiation was calculated, and mechanisms of the degradation were discussed. Gel permeation chromatography, Fourier transform infrared spectroscopy and ultraviolet-visible spectrometry (UV-VIS) were applied to characterized and analyzed the degradation products. The results indicated that molecular weight of the degraded chitosan decreased remarkably and its chemical structure changed. It was considered that OH radical is vital to the radiation degradation of chitosan. (authors)

  16. Degradation of Synthetic Dyes by Laccases – A Mini-Review

    Directory of Open Access Journals (Sweden)

    Legerská Barbora

    2016-06-01

    Full Text Available Laccases provide a promising future as a tool to be used in the field of biodegradation of synthetic dyes with different chemical structures. These enzymes are able to oxidize a wide range of phenolic substrates without the presence of additional co-factors. Laccases have been confirmed for their potential of synthetic dye degradation from wastewater and degradation products of these enzymatic reactions become less toxic than selected dyes. This study discusses the potential of laccase enzymes as agents for laccase-catalyzed degradation in terms of biodegradation efficiency of synthetic dyes, specifically: azo dyes, triphenylmethane, indigo and anthraquinone dyes. Review also summarizes the laccase-catalyzed degradation mechanisms of the selected synthetic dyes, as well as the degradation products and the toxicity of the dyes and their degradation products.

  17. Chemical Peels

    Science.gov (United States)

    ... pills, who subsequently become pregnant or have a history of brownish facial discoloration. Scarring Reactivation of cold sores What can I expect after having a chemical peel? All peels require some follow-up care: ...

  18. Unnecessary Chemicals

    Science.gov (United States)

    Johnson, Anita

    1978-01-01

    Discusses the health hazards resulting from chemical additions of many common products such as cough syrups, food dyes, and cosmetics. Steps being taken to protect consumers from these health hazards are included. (MDR)

  19. Sono-catalytic degradation of organic compounds

    International Nuclear Information System (INIS)

    Unlike aqueous effluents from the PUREX process, aqueous effluents from advanced separation processes developed to separate the minor actinides (Am, Cm) contain organic reagents in large amounts. To minimize the impact of these organic compounds on the next steps of the process, and to respect standard discharges, it is necessary to develop new techniques of degradation of organic compounds. Sono-chemistry appears as a very promising solution to eliminate organic species in aqueous nuclear effluents. Indeed, the propagation of an ultrasonic wave in a liquid medium induces the appearance of cavitation bubbles which will quickly grow and implode, causing local conditions and extreme temperatures and pressures. Each cavitation bubble can then be considered as a microreactor at high temperature and high pressure able to destroy organic molecules without the addition of specific reagents. The first studies on the effect of ultrasonic frequency on sono-luminescence and sono-lysis of formic acid have shown that the degradation of formic acid occurs at the bubble/liquid interface. The most striking difference between low-frequency and high-frequency ultrasound is that the sono-lysis of HCOOH at high ultrasonic frequencies initiates secondary reactions not observed at 20 kHz. However, despite a much higher sono-chemical activity at high frequency, highly concentrated carboxylic acids in the aqueous effluents from advanced separation processes cannot be destroyed by ultrasound alone. To increase the efficiency of sono-chemical reactions, the addition of supported platinum catalysts has been studied. In these conditions, an increase of the kinetics of destruction of carboxylic acids such as oxalic acid is observed. (author)

  20. Compendium of photovoltaic degradation rates: Photovoltaic degradation rates

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, Dirk C. [National Renewable Energy Laboratory (NREL), 15013 Denver West Parkway Golden CO 80401 USA; Kurtz, Sarah R. [National Renewable Energy Laboratory (NREL), 15013 Denver West Parkway Golden CO 80401 USA; VanSant, Kaitlyn [Colorado School of Mines, 1500 Illinois Street Golden CO 8040 USA; Newmiller, Jeff [DNV GL, 2420 Camino Ramon, Suite 300 San Ramon CA 95483 USA

    2016-02-07

    Published data on photovoltaic (PV) degradation measurements were aggregated and re-examined. The subject has seen an increased interest in recent years resulting in more than 11 000 degradation rates in almost 200 studies from 40 different countries. As studies have grown in number and size, we found an impact from sampling bias attributable to size and accuracy. Because of the correlational nature of this study we examined the data in several ways to minimize this bias. We found median degradation for x-Si technologies in the 0.5-0.6%/year range with the mean in the 0.8-0.9%/year range. Hetero-interface technology (HIT) and microcrystalline silicon (..mu..c-Si) technologies, although not as plentiful, exhibit degradation around 1%/year and resemble thin-film products more closely than x-Si. Several studies showing low degradation for copper indium gallium selenide (CIGS) have emerged. Higher degradation for cadmium telluride (CdTe) has been reported, but these findings could reflect a convolution of less accurate studies and longer stabilization periods for some products. Significant deviations for beginning-of-life measurements with respect to nameplate rating have been documented over the last 35 years. Therefore, degradation rates that use nameplate rating as reference may be significantly impacted. Studies that used nameplate rating as reference but used solar simulators showed less variation than similar studies using outdoor measurements, even when accounting for different climates. This could be associated with confounding effects of measurement uncertainty and soiling that take place outdoors. Hotter climates and mounting configurations that lead to sustained higher temperatures may lead to higher degradation in some, but not all, products. Wear-out non-linearities for the worst performing modules have been documented in a few select studies that took multiple measurements of an ensemble of modules during the lifetime of the system. However, the majority

  1. Degradación física y química de dos suelos del cordón hortícola platense: Alternativas de tratamiento Physical and chemical degradation of two horticultural soils of La Plata: Alternative treatment

    Directory of Open Access Journals (Sweden)

    Ricardo Andreau

    2012-12-01

    uso en un invernáculo con 14 años de antigüedad productiva.Horticultural and floricultural in greenhouse production requires intensive management with irrigation, fertilization and permanent tillage. This leads to irreversible soil degradation. Among the problems are those derived by sodicity, salinity, presence of toxic vegetables and loss of organic matter and physical fertility. Objectives: a assess the impact of intensive greenhouse production of different chemical and physicochemical properties in two soils of the area during 21 years, b analyze the effect of the application of different organic and chemical amendments on chemical, physical and physical-chemical variables on a Vertic Argiudol soil representative of the region with 14 years of continuous use in greenhouses, in order to select quality indicators. Soils: Serie Arturo Seguí. Antecedents: 0-21 years of cultivation under cover. Analysis: soil (pH, electrical conductivity (CE, RAS, easily oxidizable organic carbon (COT and particulate carbon (Cp, total N (Nt, extractable P, NO3-, apparent density (Dap, porosity (P, structural stability (DMP, water irrigation (CE, cations and anions, organic fertilizers (organic matter, pH, Na, humidity. Corrective treatments: T0 (witness, T1 (rice shell + gypsum + sulphur, T2 (compost + gypsum + sulphur, T3 (chicken bed (Cp + gypsum + sulphur, T4 (gypsum , T5 (sulphur, T6 (gypsum + sulphur. A progressive deterioration of the productive qualities of the soil was confirmed due to the linear increase of pH and sodicity curvilinear (RAS and salinity (CE, curvilinear decrease of COT and extractable P increases irregularly, very high in some cases. Treatments with rice shell and chicken bed, both gypsum and sulfur addition, were the most effective for the control of the loss of organic matter (COT, Cp and related physical properties (DMP, P, Dap affected by use in a greenhouse for 14 years.

  2. Atrazine and its metabolites degradation in mineral salts medium and soil using an enrichment culture.

    Science.gov (United States)

    Kumar, Anup; Singh, Neera

    2016-03-01

    An atrazine-degrading enrichment culture was used to study degradation of atrazine metabolites viz. hydroxyatrazine, deethylatrazine, and deisopropylatrazine in mineral salts medium. Results suggested that the enrichment culture was able to degrade only hydroxyatrazine, and it was used as the sole source of carbon and nitrogen. Hydroxyatrazine degradation slowed down when sucrose and/or ammonium hydrogen phosphate were supplemented as the additional sources of carbon and nitrogen, respectively. The enrichment culture could degrade high concentrations of atrazine (up to 110 μg/mL) in mineral salts medium, and neutral pH was optimum for atrazine degradation. Further, except in an acidic soil, enrichment culture was able to degrade atrazine in three soil types having different physico-chemical properties. Raising the pH of acidic soil to neutral or alkaline enabled the enrichment culture to degrade atrazine suggesting that acidic pH inhibited atrazine-degrading ability. The study suggested that the enrichment culture can be successfully utilized to achieve complete degradation of atrazine and its persistent metabolite hydroxyatrazine in the contaminated soil and water.

  3. Electron Spin Resonance Study of Fuel Cell Polymer Membrane Degradation

    Institute of Scientific and Technical Information of China (English)

    Alexander Panchenko; Elena Aleksandrova; Emil Roduner

    2005-01-01

    @@ 1Introduction The long term stability of the membrane is an important factor limiting the fuel cell lifetime. During extended use the membrane degrades, probably via reaction with hydroxyl and superoxide radicals which are regular intermediates of the oxygen reduction at the cathode. Only extremely stable membranes can withstand the aggressive chemical and physical environment in an operating fuel cell. Within a given set of operating conditions, intrinsic chemical and mechanical properties of the membrane as well as its water content impact its durability dramatically.

  4. Controlled degradation pattern of hydroxyapatite/calcium carbonate composite microspheres.

    Science.gov (United States)

    Yang, Ning; Zhong, Qiwei; Zhou, Ying; Kundu, Subhas C; Yao, Juming; Cai, Yurong

    2016-06-01

    Hydroxyapatite (HAP) is widely used in clinic due to its good biocompatibility and osteoconductivity except for its slow degradation speed. In the present study, spherical calcium carbonate (CaCO3 ) is fabricated in the presence of silk protein sericin, which is transmuted into HAP microsphere in phosphate solution with the assistance of microwave irradiation. The effect of reaction conditions on the conversion of CaCO3 is investigated including reaction time, chemical composition of phosphate solution, and microwave power to get a series of HAP/CaCO3 composites. The degradation property of the composites is evaluated in vitro. Results show the degradation speed of the composite with higher HAP content is slower. The degradation rate of the composite could be changed effectively by modulating the proportion of HAP and CaCO3 . This work provides a feasible method for the preparation of spherical HAP/CaCO3 composite with controllable degradability. The composite thus obtained may be an ideal material for bone tissue engineering application. Microsc. Res. Tech. 79:518-524, 2016. © 2016 Wiley Periodicals, Inc. PMID:27037606

  5. Degradation of transuranic-contaminated wastes under geological isolation conditions

    International Nuclear Information System (INIS)

    Results of extensive experimental studies on the degradation of existing defense transuranic-contaminated (TRU) wastes are presented. Environmental conditions for waste degradation are representative of deep geological isolation of TRU wastes in a bedded-salt repository, as anticipated for the proposed Waste Isolation Pilot Plant in southeastern New Mexico. TRU-contaminated waste matrices investigated include cellulosics, plastics, rubbers, mixed organic composite, bitumen, a developmental concrete-TRU ash matrix, mild steel, and inorganic process sludges. Degradation mechanisms studied were alpha radiolysis, microbial action, thermal decomposition and dewatering, and chemical corrosion. Experimental variables are waste composition, alpha-contamination level, temperature, pressure, time, water or brine content, aerobic or anaerobic conditions, etc. Results of waste degradation are presented in terms of gas generation rates, gas compositions, container corrosion rates, effectiveness of anti-corrosion coatings, microbial formation and degradation of chelating agents. Based on experimental results, the relative quantities of gas generated by individual mechanisms acting on the organic matrix wastes can be ranked as follows: (1) microbial action, (2) thermal decomposition (at 400C and higher), (3) alpha radiolysis, and (4) corrosion. Corrosion of metallic waste canisters and realistic bedded-salt repository conditions was determined not to have a significant effect on potential waste retrievability. The technical data provided in these studies are used in assessments to determine whether existing forms of TRU wastes are acceptable for safe geological isolation. (author)

  6. Effects of organic degradation products on the sorption of actinides

    International Nuclear Information System (INIS)

    Previous work has shown that products from the chemical degradation of cellulosic matter can significantly reduce sorption of uranium(VI) and plutonium(IV) on geological materials. Uranium(IV) batch sorption experiments have now been performed to study the effect of organic degradation products in a reducing environment. Thorium(IV) sorption has also been studied since thorium is an important radioelement in its own right and has potential use as a simulant for other tetravalent actinides. Sorption onto London clay, Caithness flagstones and St. Bees sandstone was investigated. Experimental conditions were chosen to simulate both those expected close to cementitious repository (pH ∝ 11) and at the edge of the zone of migration of the alkaline plume (pH ∝ 8). Work was carried out with both authentic degradation products and with gluconate, acting as a well-characterized simulant for cellulosic degradation products. The results show that the presence of organic species can cause a reduction in sorption. This is especially so in the presence of a high concentration of gluconate ions, but the reduction is significantly less with authentic degradation products. (orig.)

  7. DEGRADATION OF TEXTILE DYES BY WHITE ROT BASIDIOMYCETES

    Directory of Open Access Journals (Sweden)

    B.P. PARMAR, P.N. MERVANA B.R.M. VYAS*

    2014-12-01

    Full Text Available ABSTRACT: Dyes released by the textile industries pose a threat to environmental quality. Ligninolytic white-rot basidiomycetes can effectively degrade colored effluents and conventional dyes. White-rot fungi produce various isoforms of extracellular oxidases including laccase, Mn peroxidase and lignin peroxidase (LiP, which are involved in the degradation of lignin in their natural lignocellulosic substrates.  The textile industry, by far the most avid user of synthetic dyes, is in need of eco-efficient solutions for its colored effluents. White rot basidiomycetous fungi comprise the only group of organisms known to completely degrade lignin. Ligninolytic enzymes have potential applications in a large number of fields, including the chemical, fuel, food, agricultural, paper, textile, cosmetic industrial sectors and more. This ligninolytic system of white-rot fungi is also directly involved in the degradation of various xenobiotic compounds apart from textile dyes. Their capacities to remove xenobiotic substances make them a useful tool for bioremediation purposes. This paper reviews involvement of ligninolytic enzymes of white rot basidiomycetes in the degradation of textiles dyes and xenobiotic compounds for their industrial and biotechnological applications.

  8. Degradation Kinetics of Petroleum Contaminants in Soil-Water Systems

    Institute of Scientific and Technical Information of China (English)

    ZHENG Xilai; WANG Bingchen; LI Yuying; XIA Wenxiang

    2004-01-01

    On the basis of site investigation and sample collection of petroleum contaminants in the soil-water-crop system in the Shenyang-Fushun sewage irrigation area, the physical-chemical-biological compositions of the unsaturated zone is analyzed systematically in this paper. At the same time, the degradation kinetics of residual and aqueous oils is determined through biodegradation tests. The studies show that dominant microorganisms have been formed in the soils after long-term sewage irrigation. The microorganisms mainly include bacteria, and a few of fungus and actinomycetes.After a 110-days' biodegradation test, the degradation rate of residual oil is 9.74%-10.63%, while the degradation rate of aqueous oil reaches 62.43%. This indicates that the degradation rate of low-carbon aqueous oil is higher than that of highcarbon residual oil. In addition, although microbial degradation of petroleum contaminants in soils is suitable to the firstorder kinetics equation, the half-lives of aqueous oil, No. 20 heavy diesel and residual oil in the surface soils (L2-1, S1-1 and X1-1) are 1732 h, 3465 h and 17325 h, respectively.

  9. Degradation of formaldehyde in anaerobic sequencing batch biofilm reactor (ASBBR)

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, N.S. [Laboratorio de Processos Biologicos (LPB), Departamento de Hidraulica e Saneamento, Escola de Engenharia de Sao Carlos (EESC), Universidade de Sao Paulo - USP, Engenharia Ambiental, Bloco 4-F, Av. Joao Dagnone, 1100 Santa Angelina, 13.563-120 Sao Carlos, SP (Brazil); Zaiat, M. [Laboratorio de Processos Biologicos (LPB), Departamento de Hidraulica e Saneamento, Escola de Engenharia de Sao Carlos (EESC), Universidade de Sao Paulo - USP, Engenharia Ambiental, Bloco 4-F, Av. Joao Dagnone, 1100 Santa Angelina, 13.563-120 Sao Carlos, SP (Brazil)], E-mail: zaiat@sc.usp.br

    2009-04-30

    The present study evaluated the degradation of formaldehyde in a bench-scale anaerobic sequencing batch reactor, which contained biomass immobilized in polyurethane foam matrices. The reactor was operated for 212 days at 35 deg. C with 8 h sequential cycles, under different affluent formaldehyde concentrations ranging from 31.6 to 1104.4 mg/L (formaldehyde loading rates from 0.08 to 2.78 kg/m{sup 3} day). The results indicate excellent reactor stability and over 99% efficiency in formaldehyde removal, with average effluent formaldehyde concentration of 3.6 {+-} 1.7 mg/L. Formaldehyde degradation rates increased from 204.9 to 698.3 mg/L h as the initial concentration of formaldehyde was increased from around 100 to around 1100 mg/L. However, accumulation of organic matter was observed in the effluent (chemical oxygen demand (COD) values above 500 mg/L) due to the presence of non-degraded organic acids, especially acetic and propionic acids. This observation poses an important question regarding the anaerobic route of formaldehyde degradation, which might differ substantially from that reported in the literature. The anaerobic degradation pathway can be associated with the formation of long-chain oligomers from formaldehyde. Such long- or short-chain polymers are probably the precursors of organic acid formation by means of acidogenic anaerobic microorganisms.

  10. Generic Degraded Congiguration Probability Analysis for DOE Codisposal Waste Package

    Energy Technology Data Exchange (ETDEWEB)

    S.F.A. Deng; M. Saglam; L.J. Gratton

    2001-05-23

    In accordance with the technical work plan, ''Technical Work Plan For: Department of Energy Spent Nuclear Fuel Work Packages'' (CRWMS M&O 2000c), this Analysis/Model Report (AMR) is developed for the purpose of screening out degraded configurations for U.S. Department of Energy (DOE) spent nuclear fuel (SNF) types. It performs the degraded configuration parameter and probability evaluations of the overall methodology specified in the ''Disposal Criticality Analysis Methodology Topical Report'' (YMP 2000, Section 3) to qualifying configurations. Degradation analyses are performed to assess realizable parameter ranges and physical regimes for configurations. Probability calculations are then performed for configurations characterized by k{sub eff} in excess of the Critical Limit (CL). The scope of this document is to develop a generic set of screening criteria or models to screen out degraded configurations having potential for exceeding a criticality limit. The developed screening criteria include arguments based on physical/chemical processes and probability calculations and apply to DOE SNF types when codisposed with the high-level waste (HLW) glass inside a waste package. The degradation takes place inside the waste package and is long after repository licensing has expired. The emphasis of this AMR is on degraded configuration screening and the probability analysis is one of the approaches used for screening. The intended use of the model is to apply the developed screening criteria to each DOE SNF type following the completion of the degraded mode criticality analysis internal to the waste package.

  11. Clad Degradation - FEPs Screening Arguments

    Energy Technology Data Exchange (ETDEWEB)

    E. Siegmann

    2004-03-17

    The purpose of this report is to document the screening of the cladding degradation features, events, and processes (FEPs) for commercial spent nuclear fuel (CSNF). This report also addresses the effect of some FEPs on both the cladding and the CSNF, DSNF, and HLW waste forms where it was considered appropriate to address the effects on both materials together. This report summarizes the work of others to screen clad degradation FEPs in a manner consistent with, and used in, the Total System Performance Assessment-License Application (TSPA-LA). This document was prepared according to ''Technical Work Plan for Waste Form Degradation Modeling, Testing, and Analyses in Support of LA'' (BSC 2004a [DIRS 167796]).

  12. Photocatalytic degradation investigation of dicofol

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Photocatalytic degradation of dicofol was investigated on TiO2 nano particles(TiO2-NPs)under UV light irradiation.It was shown that dicofol could be completely degraded into inorganic chloride ion under the condition of 0.25 mg/mL TiO2-NPs,2 h irradiation of 400 W high pressure mercury lamp with a wavelength of 365 nm and air at a rate of 100 mL/min.The effects of the experimental conditions,including the amount of TiO2-NPs,irradiation time and the intensity of light,were studied.The apparent photodegradation rate constant was 0.167/min under the optimal condition.The photocatalytic degradation mechanism of dicofol was also discussed.

  13. Radiation degradation of silk protein

    Energy Technology Data Exchange (ETDEWEB)

    Pewlong, W.; Sudatis, B. [Office of Atomic Energy for Peace, Bangkok (Thailand); Takeshita, Hidefumi; Yoshii, Fumio; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    2000-03-01

    Silk fibroin fiber from the domesticated silkworm Bombyx mori was irradiated using an electron beam accelerator to investigate the application of the radiation degradation technique as a means to solubilize fibroin. The irradiation caused a significant degradation of the fiber. The tensile strength of fibroin fiber irradiated up to 2500 kGy decreased rapidly with increasing dose. The presence of oxygen in the irradiation atmosphere enhanced degradation of the tensile strength. The solubilization of irradiated fibroin fiber was evaluated using the following three kinds of solutions: a calcium chloride solution(CaCl{sub 2}/C{sub 2}H{sub 5}OH/H{sub 2}O=1:2:8 in mole ratio), a hydrochloric acid (0.5 N) and a distilled water. Dissolution of fibroin fiber into these solutions was significantly enhanced by irradiation. Especially, an appreciable amount of water soluble proteins was extracted by a distilled water. (author)

  14. Clad Degradation - FEPs Screening Arguments

    International Nuclear Information System (INIS)

    The purpose of this report is to document the screening of the cladding degradation features, events, and processes (FEPs) for commercial spent nuclear fuel (CSNF). This report also addresses the effect of some FEPs on both the cladding and the CSNF, DSNF, and HLW waste forms where it was considered appropriate to address the effects on both materials together. This report summarizes the work of others to screen clad degradation FEPs in a manner consistent with, and used in, the Total System Performance Assessment-License Application (TSPA-LA). This document was prepared according to ''Technical Work Plan for Waste Form Degradation Modeling, Testing, and Analyses in Support of LA'' (BSC 2004a [DIRS 167796])

  15. The Science of Battery Degradation

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, John P. [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Materials Physics; El Gabaly Marquez, Farid [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Materials Physics; McCarty, Kevin [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Materials Physics; Sugar, Joshua Daniel [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Materials Physics; Talin, Alec A. [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Materials Physics; Fenton, Kyle R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Power Sources Design and Development; Nagasubramanian, Ganesan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Power Sources Design and Development; Harris, Charles Thomas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Nanosystems Synthesis/Analysis; Jungjohann, Katherine Leigh [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Nanosystems Synthesis/Analysis; Hayden, Carl C. [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Combustion Chemistry Dept.; Kliewer, Christopher Jesse [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Combustion Chemistry Dept.; Hudak, Nicholas S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Power Sources Research and Development; Leung, Kevin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Nanostructure Physics; McDaniel, Anthony H. [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Hydrogen and Combustion Technology; Tenney, Craig M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Chemical and Biological Systems; Zavadil, Kevin R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Materials Lab.

    2015-01-01

    This report documents work that was performed under the Laboratory Directed Research and Development project, Science of Battery Degradation. The focus of this work was on the creation of new experimental and theoretical approaches to understand atomistic mechanisms of degradation in battery electrodes that result in loss of electrical energy storage capacity. Several unique approaches were developed during the course of the project, including the invention of a technique based on ultramicrotoming to cross-section commercial scale battery electrodes, the demonstration of scanning transmission x-ray microscopy (STXM) to probe lithium transport mechanisms within Li-ion battery electrodes, the creation of in-situ liquid cells to observe electrochemical reactions in real-time using both transmission electron microscopy (TEM) and STXM, the creation of an in-situ optical cell utilizing Raman spectroscopy and the application of the cell for analyzing redox flow batteries, the invention of an approach for performing ab initio simulation of electrochemical reactions under potential control and its application for the study of electrolyte degradation, and the development of an electrochemical entropy technique combined with x-ray based structural measurements for understanding origins of battery degradation. These approaches led to a number of scientific discoveries. Using STXM we learned that lithium iron phosphate battery cathodes display unexpected behavior during lithiation wherein lithium transport is controlled by nucleation of a lithiated phase, leading to high heterogeneity in lithium content at each particle and a surprising invariance of local current density with the overall electrode charging current. We discovered using in-situ transmission electron microscopy that there is a size limit to lithiation of silicon anode particles above which particle fracture controls electrode degradation. From electrochemical entropy measurements, we discovered that entropy

  16. Bacterial degradation of fungicide captan.

    Science.gov (United States)

    Megadi, Veena B; Tallur, Preeti N; Mulla, Sikandar I; Ninnekar, Harichandra Z

    2010-12-22

    The phthalimide fungicide captan has been widely used to control plant pathogenic fungi. A strain of Bacillus circulans utilized the fungicide captan as sole source of carbon and energy. The organism degraded captan by a pathway involving its initial hydrolysis to yield cis-1,2,3,6-tetrahydrophthalimide, a compound without fungicidal activity. The formation of this compound was confirmed by HPLC, IR, NMR, and mass spectral analysis. The results also revealed that cis-1,2,3,6-tetrahydrophthalimide was further degraded to o-phthalic acid by a protocatechuate pathway. These findings indicated that there was a complete mineralization of fungicide captan by B. circulans.

  17. The Science of Battery Degradation.

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, John P; Fenton, Kyle R [Sandia National Laboratories, Albuquerque, NM; El Gabaly Marquez, Farid; Harris, Charles Thomas [Sandia National Laboratories, Albuquerque, NM; Hayden, Carl C.; Hudak, Nicholas [Sandia National Laboratories, Albuquerque, NM; Jungjohann, Katherine Leigh [Sandia National Laboratories, Albuquerque, NM; Kliewer, Christopher Jesse; Leung, Kevin [Sandia National Laboratories, Albuquerque, NM; McDaniel, Anthony H.; Nagasubramanian, Ganesan [Sandia National Laboratories, Albuquerque, NM; Sugar, Joshua Daniel; Talin, Albert Alec; Tenney, Craig M [Sandia National Laboratories, Albuquerque, NM; Zavadil, Kevin R. [Sandia National Laboratories, Albuquerque, NM

    2015-01-01

    This report documents work that was performed under the Laboratory Directed Research and Development project, Science of Battery Degradation. The focus of this work was on the creation of new experimental and theoretical approaches to understand atomistic mechanisms of degradation in battery electrodes that result in loss of electrical energy storage capacity. Several unique approaches were developed during the course of the project, including the invention of a technique based on ultramicrotoming to cross-section commercial scale battery electrodes, the demonstration of scanning transmission x-ray microscopy (STXM) to probe lithium transport mechanisms within Li-ion battery electrodes, the creation of in-situ liquid cells to observe electrochemical reactions in real-time using both transmission electron microscopy (TEM) and STXM, the creation of an in-situ optical cell utilizing Raman spectroscopy and the application of the cell for analyzing redox flow batteries, the invention of an approach for performing ab initio simulation of electrochemical reactions under potential control and its application for the study of electrolyte degradation, and the development of an electrochemical entropy technique combined with x-ray based structural measurements for understanding origins of battery degradation. These approaches led to a number of scientific discoveries. Using STXM we learned that lithium iron phosphate battery cathodes display unexpected behavior during lithiation wherein lithium transport is controlled by nucleation of a lithiated phase, leading to high heterogeneity in lithium content at each particle and a surprising invariance of local current density with the overall electrode charging current. We discovered using in-situ transmission electron microscopy that there is a size limit to lithiation of silicon anode particles above which particle fracture controls electrode degradation. From electrochemical entropy measurements, we discovered that entropy

  18. Operationalizing measurement of forest degradation

    DEFF Research Database (Denmark)

    Dons, Klaus; Smith-Hall, Carsten; Meilby, Henrik;

    2015-01-01

    Quantification of forest degradation in monitoring and reporting as well as in historic baselines is among the most challenging tasks in national REDD+ strategies. However, a recently introduced option is to base monitoring systems on subnational conditions such as prevalent degradation activities...... settlements and remote forest with nearly closed canopies. Supervised classification and adaptive thresholding were applied on a pansharpened QuickBird (QB) image to detect kiln burn marks (KBMs). Supervised classification showed reasonable detection accuracy in the remote forest site only, while adaptive...

  19. Biodegradation of high molecular weight lignin under sulfate reducing conditions: lignin degradability and degradation by-products.

    OpenAIRE

    Ko, Jae-Jung; Shimizu, Yoshihisa; Ikeda, Kazuhiro; Kim, Seog-Ku; Park, Chul-Hwi; MATSUI, Saburo

    2009-01-01

    This study is designed to investigate the biodegradation of high molecular weight (HMW) lignin under sulfate reducing conditions. With a continuously mesophilic operated reactor in the presence of co-substrates of cellulose, the changes in HMW lignin concentration and chemical structure were analyzed. The acid precipitable polymeric lignin (APPL) and lignin monomers, which are known as degradation by-products, were isolated and detected. The results showed that HMW lignin decreased and showed...

  20. Degradation of 2,6-dichlorobenzonitrile and 2,6-dichlorobenzamide in groundwater sedimentary deposits and topsoil

    OpenAIRE

    Pukkila, Veera

    2015-01-01

    The worldwide use of pesticides (herbicides, insecticides, and fungisides) currently amounts to 2.4 billion kilos. Only a small proportion of pesticides actually reach the target organism, whereas the majority becomes a potent contaminant that threatens the environment and humans. Microbes, present everywhere in the environment, have the ability to degrade many kinds of man-made chemical compounds, xenobiotics. By studying the degrading microbes and the optimal conditions for microbial degrad...

  1. Optimizing Chemical Sensor Array Sizes

    International Nuclear Information System (INIS)

    Optimal selection of array sensors for a chemical sensing application is a nontrivial task. It is commonly believed that ''more is better'' when choosing the number of sensors required to achieve good chemical selectivity. However, cost and system complexity issues point towards the choice of small arrays. A quantitative array optimization is carried out to explore the selectivity of arrays of partially-selective chemical sensors as a function of array size. It is shown that modest numbers (dozens) of target analytes are completely distinguished with a range of arrays sizes. However, the array selectivity and the robustness against sensor sensitivity variability are significantly degraded if the array size is increased above a certain number of sensors, so that relatively small arrays provide the best performance. The results also suggest that data analyses for very large arrays of partially-selective sensors will be optimized by separately anal yzing small sensor subsets

  2. Formaldehyde degradation by catalytic oxidation.

    OpenAIRE

    Shirey, W N; Hall, T. A.; Hanel, E; Sansone, E B

    1981-01-01

    Formaldehyde used for the disinfection of a laminar-flow biological safety cabinet was oxidatively degraded by using a catalyst. This technique reduced the formaldehyde concentration in the cabinet from about 5,000 to about 45 mg/m3 in 8 h. This technique should prove useful in other applications.

  3. Degradable polyethylene: fantasy or reality.

    Science.gov (United States)

    Roy, Prasun K; Hakkarainen, Minna; Varma, Indra K; Albertsson, Ann-Christine

    2011-05-15

    Plastic waste disposal is one of the serious environmental issues being tackled by our society today. Polyethylene, particularly in packaging films, has received criticism as it tends to accumulate over a period of time, leaving behind an undesirable visual footprint. Degradable polyethylene, which would enter the eco-cycle harmlessly through biodegradation would be a desirable solution to this problem. However, the "degradable polyethylene" which is presently being promoted as an environmentally friendly alternative to the nondegradable counterpart, does not seem to meet this criterion. This article reviews the state of the art on the aspect of degradability of polyethylene containing pro-oxidants, and more importantly the effect these polymers could have on the environment in the long run. On exposure to heat, light, and oxygen, these polymers disintegrate into small fragments, thereby reducing or increasing the visual presence. However, these fragments can remain in the environment for prolonged time periods. This article also outlines important questions, particularly in terms of time scale of complete degradation, environmental fate of the polymer residues, and possible accumulation of toxins, the answers to which need to be established prior to accepting these polymers as environmentally benign alternatives to their nondegradable equivalents. It appears from the existing literature that our search for biodegradable polyethylene has not yet been realized. PMID:21495645

  4. Photoelectrocatalytic degradation of Rose Bengal

    Institute of Scientific and Technical Information of China (English)

    LIU Hui-ling; ZHOU Ding; LI Xiang-zhong; YUE Ping-tao

    2003-01-01

    An innovative photoelectrode, TiO2/Ti mesh electrode, was prepared by galvanostaticanodisation. The morphology and the crystalline texture of the TiO2 film on mesh electrode were examined by scanning electronic microscopy and Raman spectroscopy respectively. The examination results indicated that the structure and properties of the film depended on anodisation rate, and the anatase was the dominant component under the controlled experimental conditions. Degradation of Rose Bengal(RB) in photocatalytic(PC) and photoelectrocatalytic(PEC) reaction was investigated, the results demonstrated that electric biasing could improve the efficiency of photocatalytic reaction. The measurement results of TOC in photoelectrocatalytic degradation showed that the mineralisation of RB was complete relatively. The comparison between the degradation efficiency of RB in PEC process and that in aqueous TiO2 dispersion was conducted. The results showed that the apparent first-order rate constant of RB degradation in PEC process was larger than that in aqueous dispersion with 0.1%-0.3% TiO2 powder, but was smaller than that in aqueous dispersion with 1.0% TiO2.

  5. Environmental Degradation of Solar Reflectors

    Science.gov (United States)

    Bouquet, F. L.

    1985-01-01

    Report presents results of study of atmospheric degradation of large solar reflectors for power generators. Three general types of reflective surfaces investigated. Report also describes computer buildup and removal (by rain and dew) of contamination from reflectors. Data used to determine effects of soil buildup and best method and frequency of washing at various geographic locations.

  6. Chemical Mahjong

    Science.gov (United States)

    Cossairt, Travis J.; Grubbs, W. Tandy

    2011-01-01

    An open-access, Web-based mnemonic game is described whereby introductory chemistry knowledge is tested using mahjong solitaire game play. Several tile sets and board layouts are included that are themed upon different chemical topics. Introductory tile sets can be selected that prompt the player to match element names to symbols and metric…

  7. Chemical Peels

    Science.gov (United States)

    ... resources Meet our partners Español Donate Diseases and treatments Acne and rosacea Bumps and growths Color problems Contagious skin diseases ... Chemical peels public SPOT Skin Cancer™ Diseases and treatments Acne and rosacea Bumps and growths Color problems Contagious skin diseases ...

  8. Chemical pressure

    OpenAIRE

    Hauser, Andreas; Amstutz, Nahid; Delahaye, Sandra; Sadki, Asmaâ; Schenker, Sabine; Sieber, Regula; Zerara, Mohamed

    2002-01-01

    The physical and photophysical properties of three classic transition metal complexes, namely [Fe(bpy)3]2+, [Ru(bpy)3]2+, and [Co(bpy)3]2+, can be tuned by doping them into a variety of inert crystalline host lattices. The underlying guest-host interactions are discussed in terms of a chemical pressure.

  9. Chemical dispersants

    NARCIS (Netherlands)

    Rahsepar, Shokouhalsadat; Smit, Martijn P.J.; Murk, Albertinka J.; Rijnaarts, Huub H.M.; Langenhoff, Alette A.M.

    2016-01-01

    Chemical dispersants were used in response to the Deepwater Horizon oil spill in the Gulf of Mexico, both at the sea surface and the wellhead. Their effect on oil biodegradation is unclear, as studies showed both inhibition and enhancement. This study addresses the effect of Corexit on oil biodeg

  10. Modeling chlorophenols degradation in sequencing batch reactors with instantaneous feed-effect of 2,4-DCP presence on 4-CP degradation kinetics.

    Science.gov (United States)

    Sahinkaya, Erkan; Dilek, Filiz B

    2007-08-01

    Two instantaneously fed sequencing batch reactors (SBRs), one receiving 4-chlorophenol (4-CP) (SBR4) only and one receiving mixture of 4-CP and 2,4-dichlorophenol (2,4-DCP) (SBRM), were operated with increasing chlorophenols concentrations in the feed. Complete degradation of chlorophenols and high-Chemical oxygen demand (COD) removal efficiencies were observed throughout the reactors operation. Only a fraction of biomass (competent biomass) was thought to be responsible for the degradation of chlorophenols due to required unique metabolic pathways. Haldane model developed based on competent biomass concentration fitted reasonably well to the experimental data at different feed chlorophenols concentrations. The presence of 2,4-DCP competitively inhibited 4-CP degradation and its degradation began only after complete removal of 2,4-DCP. Based on the experimental results, the 4-CP degrader's fraction in SBRM was estimated to be higher than that in SBR4 since 2,4-DCP degraders were also capable of degrading 4-CP due to similarity in the degradation pathways of both compounds. PMID:17091347

  11. Modeling chlorophenols degradation in sequencing batch reactors with instantaneous feed-effect of 2,4-DCP presence on 4-CP degradation kinetics.

    Science.gov (United States)

    Sahinkaya, Erkan; Dilek, Filiz B

    2007-08-01

    Two instantaneously fed sequencing batch reactors (SBRs), one receiving 4-chlorophenol (4-CP) (SBR4) only and one receiving mixture of 4-CP and 2,4-dichlorophenol (2,4-DCP) (SBRM), were operated with increasing chlorophenols concentrations in the feed. Complete degradation of chlorophenols and high-Chemical oxygen demand (COD) removal efficiencies were observed throughout the reactors operation. Only a fraction of biomass (competent biomass) was thought to be responsible for the degradation of chlorophenols due to required unique metabolic pathways. Haldane model developed based on competent biomass concentration fitted reasonably well to the experimental data at different feed chlorophenols concentrations. The presence of 2,4-DCP competitively inhibited 4-CP degradation and its degradation began only after complete removal of 2,4-DCP. Based on the experimental results, the 4-CP degrader's fraction in SBRM was estimated to be higher than that in SBR4 since 2,4-DCP degraders were also capable of degrading 4-CP due to similarity in the degradation pathways of both compounds.

  12. Chemical Analyses of Silicon Aerogel Samples

    CERN Document Server

    van der Werf, I; De Leo, R; Marrone, S

    2008-01-01

    After five years of operating, two Aerogel counters: A1 and A2, taking data in Hall A at Jefferson Lab, suffered a loss of performance. In this note possible causes of degradation have been studied. In particular, various chemical and physical analyses have been carried out on several Aerogel tiles and on adhesive tape in order to reveal the presence of contaminants.

  13. Interfacial Degradation of Planar Lead Halide Perovskite Solar Cells.

    Science.gov (United States)

    Guerrero, Antonio; You, Jingbi; Aranda, Clara; Kang, Yong Soo; Garcia-Belmonte, Germà; Zhou, Huanping; Bisquert, Juan; Yang, Yang

    2016-01-26

    The stability of perovskite solar cells is one of the major challenges for this technology to reach commercialization, with water believed to be the major degradation source. In this work, a range of devices containing different cathode metal contacts in the configuration ITO/PEDOT:PSS/MAPbI3/PCBM/Metal are fully electrically characterized before and after degradation caused by steady illumination during 4 h that induces a dramatic reduction in power conversion efficiency from values of 12 to 1.8%. We show that a decrease in performance and generation of the S-shape is associated with chemical degradation of the metal contact. Alternatively, use of Cr2O3/Cr as the contact enhances the stability, but modification of the energetic profile during steady illumination takes place, significantly reducing the performance. Several techniques including capacitance-voltage, X-ray diffraction, and optical absorption results suggest that the properties of the bulk perovskite layer are little affected in the device degradation process. Capacitance-voltage and impedance spectroscopy results show that the electrical properties of the cathode contact are being modified by generation of a dipole at the cathode that causes a large shift of the flat-band potential that modifies the interfacial energy barrier and impedes efficient extraction of electrons. Ionic movement in the perovskite layer changes the energy profile close to the contacts, modifying the energy level stabilization at the cathode. These results provide insights into the degradation mechanisms of perovskite solar cells and highlight the importance to further study the use of protecting layers to avoid the chemical reactivity of the perovskite with the external contacts. PMID:26679510

  14. Cinética de degradação da matéria orgânica de biossólidos após aplicação no solo e relação com a composição química inicial Degradation kinetics of biosolids organic matter after soil application and its relationship with initial chemical composition

    Directory of Open Access Journals (Sweden)

    Cristiano Alberto de Andrade

    2006-01-01

    after soil application, in relation to the initial organic matter (OM chemical composition of the residue. Four biosolids and sewage sludge compost differentiated by being originated from different waste systems and/or sludge stabilization process and/or chemical conditioning to dehydration and/or additional treatment to adequate the residue for agricultural application were used. Biosolids degradation was determinated in a experiment done to quantify CO2 emitted from Oxisol samples incubated with biosolids in a dose correspondent to 40 t ha¹. The degradation rates of biosolids organic matter were between 5% - 22%. In general, the biosolids organic matter decomposition was described by a two-stage equation of chemical kinetics: the first stage showed high decomposition velocity and organic compounds exhausted in few days (2 to 20 days; whereas the second stage had a reduced decomposition velocity in comparison to the first phase, and a relative increase of mineralized carbon (³ 65% of total degraded carbon during all incubation period. Gross protein, expressed as organic residue content, was the parameter better correlated with biosolids degradation rate at the end of 70 days of incubation (r = 0.999 e Prob. > t lower than 10-4, its utilization being prospective to biosolids organic matter degradation after addition to soils. Protein pool participation increased with incubation time, indicating that in the beginning of the experiment more labile organic compounds worked as carbon and energy sources for the edafic microbiota.

  15. Fast degradation of dyes in water using manganese-oxide-coated diatomite for environmental remediation

    Science.gov (United States)

    Dang, Trung-Dung; Banerjee, Arghya Narayan; Tran, Quang-Tung; Roy, Sudipta

    2016-11-01

    By a simple wet-chemical procedure using a permanganate in the acidic medium, diatomite coated with amorphous manganese oxide nanoparticles was synthesized. The structural, microstructural and morphological characterizations of the as-synthesized catalysts confirmed the nanostructure of MnO2 and its stabilization on the support - diatomite. The highly efficient and rapid degradation of methylene blue and methyl orange over synthesized MnO2 coated Diatomite has been carried out. The results revealed considerably faster degradation of the dyes against the previously reported data. The proposed mechanism of the dye-degradation is considered to be a combinatorial effect of chemical, physicochemical and physical processes. Therefore, the fabricated catalysts have potential application in waste water treatment, and pollution degradation for environmental remediation.

  16. Exploring the planetary boundary for chemical pollution

    DEFF Research Database (Denmark)

    Diamond, Miriam L.; de Wit, Cynthia A.; Molander, Sverker;

    2015-01-01

    forward, at this point single or multiple PBCPs are challenging to operationalize due to the extremely large number of commercial chemicals or mixtures of chemicals that cause myriad adverse effects to innumerable species and ecosystems, and the complex linkages between emissions, environmental......Rockström et al. (2009a, 2009b) have warned that humanity must reduce anthropogenic impacts defined by nine planetary boundaries if "unacceptable global change" is to be avoided. Chemical pollution was identified as one of those boundaries for which continued impacts could erode the resilience...... of ecosystems and humanity. The central concept of the planetary boundary (or boundaries) for chemical pollution (PBCP or PBCPs) is that the Earth has a finite assimilative capacity for chemical pollution, which includes persistent, as well as readily degradable chemicals released at local to regional scales...

  17. Transport and degradation of propylene glycol in the vadose zone: model development and sensitivity analysis.

    Science.gov (United States)

    Schotanus, D; Meeussen, J C L; Lissner, H; van der Ploeg, M J; Wehrer, M; Totsche, K U; van der Zee, S E A T M

    2014-01-01

    Transport and degradation of de-icing chemical (containing propylene glycol, PG) in the vadose zone were studied with a lysimeter experiment and a model, in which transient water flow, kinetic degradation of PG and soil chemistry were combined. The lysimeter experiment indicated that aerobic as well as anaerobic degradation occurs in the vadose zone. Therefore, the model included both types of degradation, which was made possible by assuming advection-controlled (mobile) and diffusion-controlled (immobile) zones. In the mobile zone, oxygen can be transported by diffusion in the gas phase. The immobile zone is always water-saturated, and oxygen only diffuses slowly in the water phase. Therefore, the model is designed in a way that the redox potential can decrease when PG is degraded, and thus, anaerobic degradation can occur. In our model, manganese oxide (MnO2, which is present in the soil) and NO3- (applied to enhance biodegradation) can be used as electron acceptors for anaerobic degradation. The application of NO3- does not result in a lower leaching of PG nor in a slower depletion of MnO2. The thickness of the snowcover influences the leached fraction of PG, as with a high infiltration rate, transport is fast, there is less time for degradation and thus more PG will leach. The model showed that, in this soil, the effect of the water flow dominates over the effect of the degradation parameters on the leaching at a 1-m depth. PMID:24002660

  18. Detailed modeling of the atmospheric degradation mechanism of very-short lived brominated species

    OpenAIRE

    G. Krysztofiak; Catoire, Valéry; Poulet, G.; Marécal, V.; Pirre, Michel; Louis, F.; Canneaux, S.; B. Josse

    2012-01-01

    International audience Detailed chemical reaction schemes for the atmospheric degradations of the very short-lived species (VSLS) bromoform (CHBr3) and dibromomethane (CH2Br2) have been established. These degradation schemes have been implemented in the meteorological/tracer transport model CATT-BRAMS used in the present case as pseudo one-dimensional model with chemistry of CH4, CO, HOx, NOx, NOy and Ox. They include the main possible reactions of the intermediate brominated peroxy radica...

  19. PHOTOCATALYTIC DEGRADATION OF WASTE WATER ON. THIN FILMS OF TiO2

    Institute of Scientific and Technical Information of China (English)

    Wu Zhenghuang

    2001-01-01

    The degradation of organic phosphorous pesticide waste water using thin films of TiO2, which was prepared in an atmospheric vertical chemical vapor deposition system, was studied. The results show that the wafer material for coating TiO2, the photocatalytic time, the TiO2 crystal phase, the pH value and the concentration of pesticides in waste water influence the degradation rate. These facts indicate some potential for photocatalytic treatment of waste water by utilizing sunlight.

  20. Investigation on the Degradation Mechanism of Pressure Reducing Orifice of Nuclear Power Plant

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sun-ki; Lee, Sang-guk; Park, Sung-gun [Korea Electric Power Research Institute, Daejeon (Korea, Republic of)

    2007-07-01

    During the nuclear power plant periodical inspection, crack was detected at the pressure reducing orifice down stream in the Chemical and Volume Control System (CVCS). Damage is serious at the orifice outlet. This Paper examined the degradation mechanism of reduce pressure orifice of CVCS by the measuring vibration and frequency analysis, internal flow pattern analysis. Results show that the degradation of the pressure reducing orifice was caused cavitation, and suggest design improvement plan for damage prevention.

  1. Partial discharge energy and electrical tree volume degraded in epoxy resin

    OpenAIRE

    R. Schurch, S. M. Rowland and R. S. Bradley

    2015-01-01

    Electrical trees are hollow artifacts resembling botanical trees generated in high electrical fields, and are a form of polymeric insulation degradation. Most models assume partial discharges, which accompany tree growth, are the cause of material degradation, and so understanding the energy associated with discharges and the energy of vaporization of the material chemical constituents is critical. In this study the volume of trees has been determined through an X-ray Computed Tomography tech...

  2. Thermal degradation of PVC: A review.

    Science.gov (United States)

    Yu, Jie; Sun, Lushi; Ma, Chuan; Qiao, Yu; Yao, Hong

    2016-02-01

    This review summarized various chemical recycling methods for PVC, such as pyrolysis, catalytic dechlorination and hydrothermal treatment, with a view to solving the problem of energy crisis and the impact of environmental degradation of PVC. Emphasis was paid on the recent progress on the pyrolysis of PVC, including co-pyrolysis of PVC with biomass/coal and other plastics, catalytic dechlorination of raw PVC or Cl-containing oil and hydrothermal treatment using subcritical and supercritical water. Understanding the advantage and disadvantage of these treatment methods can be beneficial for treating PVC properly. The dehydrochlorination of PVC mainly happed at low temperature of 250-320°C. The process of PVC dehydrochlorination can catalyze and accelerate the biomass pyrolysis. The intermediates from dehydrochlorination stage of PVC can increase char yield of co-pyrolysis of PVC with PP/PE/PS. For the catalytic degradation and dechlorination of PVC, metal oxides catalysts mainly acted as adsorbents for the evolved HCl or as inhibitors of HCl formation depending on their basicity, while zeolites and noble metal catalysts can produce lighter oil, depending the total number of acid sites and the number of accessible acidic sites. For hydrothermal treatment, PVC decomposed through three stages. In the first region (T<250°C), PVC went through dehydrochlorination to form polyene; in the second region (250°C

  3. Biodegradation of degradable plastic polyethylene by phanerochaete and streptomyces species.

    Science.gov (United States)

    Lee, B; Pometto, A L; Fratzke, A; Bailey, T B

    1991-03-01

    The ability of lignin-degrading microorganisms to attack degradable plastics was investigated in pure shake flask culture studies. The degradable plastic used in this study was produced commercially by using the Archer-Daniels-Midland POLYCLEAN masterbatch and contained pro-oxidant and 6% starch. The known lignin-degrading bacteria Streptomyces viridosporus T7A, S. badius 252, and S. setonii 75Vi2 and fungus Phanerochaete chrysosporium were used. Pro-oxidant activity was accelerated by placing a sheet of plastic into a drying oven at 70 degrees C under atmospheric pressure and air for 0, 4, 8, 12, 16, or 20 days. The effect of 2-, 4-, and 8-week longwave UV irradiation at 365 nm on plastic biodegradability was also investigated. For shake flask cultures, plastics were chemically disinfected and incubated-shaken at 125 rpm at 37 degrees C in 0.6% yeast extract medium (pH 7.1) for Streptomyces spp. and at 30 degrees C for the fungus in 3% malt extract medium (pH 4.5) for 4 weeks along with an uninoculated control for each treatment. Weight loss data were inconclusive because of cell mass accumulation. For almost every 70 degrees C heat-treated film, the Streptomyces spp. demonstrated a further reduction in percent elongation and polyethylene molecular weight average when compared with the corresponding uninoculated control. Significant (P degradation by the fungus was observed. To our knowledge, this is the first report demonstrating bacterial degradation of these oxidized polyethylenes in pure culture. PMID:16348434

  4. Detection of the spectroscopic signatures of explosives and their degradation products

    Science.gov (United States)

    Florian, Vivian; Cabanzo, Andrea; Baez, Bibiana; Correa, Sandra; Irrazabal, Maik; Briano, Julio G.; Castro, Miguel E.; Hernandez-Rivera, Samuel P.

    2005-06-01

    Detection and removal of antipersonnel and antitank landmines is a great challenge and a worldwide enviromental and humanitarian problem. Sensors tuned on the spectroscopic signature of the chemicals released from mines are a potential solution. Enviromental factors (temperature, relative humidity, rainfall precipitation, wind, sun irradiation, pressure, etc.) as well as soil characteristics (water content, compaction, porosity, chemical composition, particle size distribution, topography, vegetation, etc), have a direct impact on the fate and transport of the chemicals released from landmines. Chemicals such as TNT, DNT and their degradation products, are semi-volatile, and somewhat soluble in water. Also, they may adsorb strongly to soil particles, and are susceptible to degradation by microorganisms, light, or chemical agents. Here we show an experimental procedure to quantify the effect of the above variables on the spectroscopic signature. A number of soil tanks under controlled conditions are used to study the effect of temperature, water content, relative humidity and light radiation.

  5. Degradation kinetics and mechanisms of phenol in photo-Fenton process

    Institute of Scientific and Technical Information of China (English)

    何锋; 雷乐成

    2004-01-01

    Phenol degradation in photochemically enhanced Fenton process was investigated in this work. UV-VIS spectra of phenol degradation showed the difference between photo-Fenton process and UV/H2O2, which is a typical hydroxyl radical process. A possible pathway diagram for phenol degradation in photo-Fenton process was proposed, and a mathematical model for chemical oxygen demand (COD) removal was developed. Operating parameters such as dosage of H2O2 and ferrous ions, pH, suitable carrier gas were found to impact the removal of COD significantly. The results and analysis of kinetic parameters calculated from the kinetic model showed that complex degradation of phenol was the main pathway for removal of COD; while hydroxyl radicals acted weakly in the photo-Fenton degradation of phenol.

  6. Enhanced degradation of metalaxyl in agricultural soils of São Paulo State, Brazil

    Directory of Open Access Journals (Sweden)

    Papini Solange

    2001-01-01

    Full Text Available This work investigated the effect of repeated applications on enhanced degradation of metalaxyl in two different agricultural soils used for cultivation of orange and lemon from Casa Branca and Itapetininga districts of São Paulo State, Brazil. Soil samples were collected from areas repeatedly treated with commercial ridomil 50GR for six successive years, and from other areas never exposed to this fungicide. At the laboratory, soil samples received a 14C-metalaxyl solution and its degradation was studied through radiometric techniques to measure biomineralization and recovery of extractable- and soil-bound products. Enhanced degradation was verified only in one soil, although partial degradation and mineralization of the fungicide were detected in both soils. The different rates and patterns of metalaxyl degradation in the soils were probably due to their different physical, chemical, and biological characteristics.

  7. The degradation, antioxidant and antimutagenic activity of the mucilage polysaccharide from Dioscorea opposita.

    Science.gov (United States)

    Zhang, Zhongshan; Wang, Xiaomei; Liu, Chongbin; Li, Jingfen

    2016-10-01

    The mucilage polysaccharide was extracted from Dioscorea opposita in cold water and then degraded in two reagents hydrogen peroxide and ascorbic acid. Three low-molecular-weight-samples were prepared, and their antioxidant and antimutagenic activity were investigated. Chemical composition analysis indicated that the degradation action was in a concentration dependent manner. Total sugars content of three degraded samples were significantly higher than raw sample. The uronic acid content in the degraded sample LP3 was significantly higher than other samples. LP3 processed the higher scavenging effect on hydroxyl and superoxide radicals than other two degraded samples because of its lower molecular weight and more uronic acid. LP3 processed the excellent antimutagenic activity and higher anti-lipid peroxidation in garlic roots. There maybe a certain relationship between the two activities. The present results indicated this mucilage could be a potential candidate of the natural antimutagen. PMID:27312633

  8. The influence of the environment on the degradation of polylactides and their composites

    Directory of Open Access Journals (Sweden)

    J. Chłopek

    2010-11-01

    Full Text Available Purpose: The aim of this paper was to determine the influence of environment on degradation process of polylactide-based materials assigned for the implementation in medical implants and short-life products. The hydrolytic degradation, the biodegradation and the degradation under in vivo conditions were determined for the polylactide (PLA, the lactide and glycolide copolymer (PGLA and the composites modified by hydroxyapatite particles, carbon fibres and natural fibres (hemp, jute.Design/methodology/approach: The degradation was analyzed on the basis of the changes occurring in the environment (such as those in pH fluids, the changes of the mass and resistance of the examined materials, as well as the structural infrared analyses.Findings: It was stated that the degradation time depends on the type of the environment with which the material is in contact. In the water environment, the degradation is faster than in the presence of a compost, and in the Ringer fluid, its speed is higher than in the artificial serum SBF. The in vitro observations focus mainly on the chemical interaction between the examined materials and the artificial environment. The degradation speed is dependent, among others, on the viscosity of the applied fluids and thus, their ability of penetration in the polymer’s structure and on the interfacial boundaries. In a living organism, the fundamental role is played by such processes as the protein adsorption, the cellular and tissue reactions, the body fluid flows and the charge exchanges, and thus, the degradation process is significantly faster than that under in vitro conditions.Practical implications: Result of this study can be used to elaborate the manufacturing method of implants with controlled resorption time and degradable short life time products like packages.Originality/value: In this paper effect of hydrolytic degradation, biodegradation and in vivo degradation on polymers’ and composites’ behaviour was

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

    International Nuclear Information System (INIS)

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

  10. Microstructural degradation in compound tubes

    Energy Technology Data Exchange (ETDEWEB)

    Salonen, J.; Auerkari, P. [VTT Manufacturing Technology, Espoo (Finland)

    1996-12-31

    In order to quantify microstructural degradation at high temperatures, samples of SA 210 / AISI 304 L compound tube material were annealed in the temperature range 540-720 deg C for 1 to 1 000 hours. The hardness of the annealed material was measured and the micro structure of the samples was investigated with optical and scanning electron microscopy. Microstructural degradation was characterised by the carbide structure in the ferritic-pearlitic base material and by the depth of decarburised and carburised zones of the compound tube interface. The observed changes were quantified in terms of their time and temperature dependence and diffusion coefficients of the process. The results can be used in estimating the extent of thermal exposure of high-temperature components after long-term service or after incidences of overheating. (orig.) (4 refs.)

  11. Environmental Degradation: Causes and Consequences

    OpenAIRE

    Swati Tyagi; Neelam Garg; Rajan Paudel

    2014-01-01

    The subject of environmental economics is at the forefront of the green debate: the environment can no longer be viewed as an entity separate from the economy. Environmental degradation is of many types and have many consequences. To address this challenge a number of studies have been conducted in both developing and developed countries applying different methods to capture health benefits from improved environmental quality. Minimizing exposure to environmental risk factors by enhancing air...

  12. Degradation of Methyldopa by Banana

    OpenAIRE

    Kiminori Mohri; Yoshihiro Uesawa

    2010-01-01

    Methyldopa, an antihypertensive, is a very close analogue of DOPA. Drug interaction accompanied by degradation in a banana juice mixture was reported for DOPA. However, the effect of banana on methyldopa has not been reported. Therefore, we have investigated the impact of banana juice on methyldopa. The drug and supernatant of banana pulp were mixed, and the mixture was observed for changes in color, drug concentration, and ultraviolet-visible absorption spectra at 30 °C. The originally clear...

  13. Strength Degradation of Gfrp Bars

    OpenAIRE

    Bhise, Vikrant Sudhakar

    2002-01-01

    The primary objective of this research was to examine the strength degradation of Glass Fiber Reinforced Polymer (GFRP) bars at high temperature and alkalinity and determine if an Arrhenius type relationship can be used as a means of projecting life. The work done includes a thorough literature review, experiments and development of strength prediction models. The experimental work involves exposure of GFRP bars incased in cement mortar to lime-water solution at 30, 45 and 57°C. Overall 100 ...

  14. On the Degradation Mechanism of Low-Voltage Underground Cable with Poly(Vinyl Chloride) Insulation

    Science.gov (United States)

    Tawancy, H. M.; Hassan, M.

    2016-06-01

    A study has been undertaken to determine the degradation mechanism leading to localized short-circuit failures of an underground low-voltage cable with PVC insulation. It is shown that that the insulation of outer sheath and conductor cores has been cracked by thermal degradation involving dehydrochlorination, oxidation, and loss of plasticizers leading to current leakage between the cores. Most evidence points out that overheating due to poor connection of copper wires as well as a chemically active soil has caused the observed degradation.

  15. [Study on continued degradation of BaP and its metabolites].

    Science.gov (United States)

    Zang, Shu-yan; Li, Pei-Jun; Zhou, Qi-xing; Wang, Xin; Lin, Gui-feng; Wang, Juan

    2006-12-01

    Two metabolites, cis-BP4, 5-dihydrodiol and cis-BP7, 8-dihydrodiol, were identified by high-performance liquid chromatography (HPLC) during the degradation of BaP by Bacillus-07 (BA-07). The two metabolites were hardly further metabolized for their toxicity to microorganism. To promote degradation of BaP and decrease accumulation of cis-BP4, 5-dihydrodiol and cis-BP7, 8-dihydrodiol, two methods (degradation only by BA-07, degradation by coupling the BA-07 and KMnO4) were compared. In addition, parameters of continued degradation of BaP and the two metabolites were optimized under the experiment conditions. The results showed that (1)the method of coupling the chemical oxidation and biodegradation (BA-07 and KMnO4) was better than only biodegradation (BA-07); (2) residue rate of cis-BP4, 5-dihydrodiol was higher than that of cis-BP7, 8-dihydrodiol when the samples were determined in the same time; (3)the effect of continued degradation was the best when the initial concentration of BaP was 40 microg/mL, pH value of the culture was 7.0, co-metabolic substrates was sodium succinate. Meanwhile, it was put forward that the method of coupling the chemical oxidation and biodegradation was effective on continued degradation of persistent organic contaminants in the environment.

  16. Abundance of polymers degrading microorganisms in a sea-based solid waste disposal site.

    Science.gov (United States)

    Ishigaki, T; Sugano, W; Ike, M; Kawagoshi, Y; Fukunaga, I; Fujita, M

    2000-01-01

    In order to assess the degradability of plastics in solid waste disposal landfill sites, microbial populations capable of degrading five kinds of plastic-constituting polymers, poly epsilon-caprolactone (PCL), polylactic acid (PLA), polyethylene glycol (PEG), poly-beta-hydroxybutyrate (PHB) and cellulose acetate (CA), in a sea-based solid waste disposal site were investigated. Enumeration of aerobic and anaerobic polymers-degrading microorganisms (PDMs) was performed against to total 8 leachate samples, which were seasonally collected from the facultative pretreatment pond and the aerated lagoon. Both aerobic and anaerobic PDMs for natural polymers, PHB and CA, were found in all of the samples, while those for chemically-synthesized polymers, PCL, PLA and PEG, could not be always detected. In most cases, the ratios of the PHB- and CA-degraders to the heterotrophic bacterial population were more than 0.1%. On the other hand, the ratios of PCL-, PLA- and PEG-degraders were often much lower. These data indicate that the plastics degradation potential is commonly present in the studied disposal site, and that the degradation potential for plastics composed of chemically-synthesized polymers is inferior to that of natural polymers. Population sizes of the PDMs correlated to those of heterotrophic bacteria, and the counts of aerobic heterotrophic bacteria and PDMs in the aerated lagoon tended to be higher than those of anaerobic ones, indicating that the aeration of the leachate resulted in the activation of growth of whole aerobic microbial community including the PDMs. PMID:10957959

  17. A review of the gas diffusion layer in proton exchange membrane fuel cells: Durability and degradation

    International Nuclear Information System (INIS)

    Highlights: • This paper focuses on the evaluation of the durability characteristics of GDL. • GDL degradation can be categorized into mechanical and chemical degradation. • Standardized test protocols need to be established to evaluate GDL durability. - Abstract: For successful commercialization of a proton exchange membrane fuel cell, the durability requirement must be satisfied. The degradation of a proton exchange membrane fuel cell has been extensively studied, and a number of review papers investigating the durability issue have already been published. However, the gas diffusion layer has rarely been examined, even though it might be a key factor for managing mass transport and two-phase flow while mechanically supporting a membrane-electrode assembly and a bipolar plate. This paper reviews the published works on the durability of the gas diffusion layer of the proton exchange membrane fuel cell. The degradation of the gas diffusion layer can be divided into mechanical degradation, including the compression force effect, freeze/thaw cycle effect, dissolution effect, and erosion effect, and chemical degradation, which consists of the carbon corrosion effect. Following these categories, the methods of accelerated stress tests, the degradation mechanisms, and the influential factors are investigated along with various measurements of gas diffusion layer properties and cell performances

  18. PEM Degradation Investigation Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Dan Stevenson; Lee H Spangler

    2010-10-18

    This project conducted fundamental studies of PEM MEA degradation. Insights gained from these studies were disseminated to assist MEA manufacturers in understanding degradation mechanisms and work towards DOE 2010 fuel cell durability targets.

  19. Degradation of electrochromic film of amorphous tungsten oxide after coloration

    Science.gov (United States)

    Luo, Zhongkuan

    1992-11-01

    The degradation of the electrochromic film of a-WO3 was investigated from the equilibrium state of different driving voltage and the time dependent emf was also obtained in an open or short circuit of zero volts. Based on the mechanism of activation and the principal of chemical reaction kinetics, the correct definition of electrochromic memory was made and a relation of memory was obtained. It was also found that at the initial time of natural bleaching, the change rate of proton concentration in the film was also obtained. According to the mechanism of electrochromic memory, it was indicated that in the open circuit case, the theoretical reaction of the change rate of electric potential was in good agrement with the experimental results, and furthermore, the reaction constant was determined with the experimental data. In the short circuit case, there exist two effects on degradation, the short circuit current caused by the backward emf, and the oxidation of the colored film. The experimental data shows that, in the short circuit case, the degradation strongly depends on the short circuit current and the effect of chemical reaction can be neglected.

  20. Formulation, stability and degradation kinetics of intravenous cinnarizine lipid emulsion.

    Science.gov (United States)

    Shi, Shuai; Chen, Hao; Cui, Yue; Tang, Xing

    2009-05-21

    Cinnarizine was loaded in the lipid emulsion to develop an intravenous formulation with good physical and chemical stability. High-pressure homogenization was used to prepare the lipid emulsion. The factors influencing the stability of cinnarizine lipid emulsion, such as different drug loading methods, pH, temperature, sterilization methods and sterilization time were monitored by high-performance liquid chromatograph. The degradation of cinnarizine in aqueous solution and lipid emulsion both followed apparent first-order kinetics. A possible degradation mechanism was postulated by the bell-shaped pH-rate profile of cinnarizine. Localization of the drug in the interfacial lecithin layer significantly improved the chemical stability of cinnarizine and its stabilizing mechanism was thoroughly discussed and proved. The activation energy of cinnarizine in lipid emulsion was calculated to be 51.27 kJ/mol which was similar to that in aqueous solution. This indicates that the stabilizing effect of the drug carrier on cinnarizine was not an alteration of the degradation reaction. In addition, shelf-life of cinnarizine in lipid emulsion was estimated to be 1471.6 days at 4 degrees C, which is much longer compared with 19.8 days in aqueous solution. The final products were stable enough to resist a 121 degrees C rotating steam sterilization for 15 min. PMID:19429300

  1. Ozone degrades floral scent and reduces pollinator attraction to flowers.

    Science.gov (United States)

    Farré-Armengol, Gerard; Peñuelas, Josep; Li, Tao; Yli-Pirilä, Pasi; Filella, Iolanda; Llusia, Joan; Blande, James D

    2016-01-01

    In this work we analyzed the degradation of floral scent volatiles from Brassica nigra by reaction with ozone along a distance gradient and the consequences for pollinator attraction. For this purpose we used a reaction system comprising three reaction tubes in which we conducted measurements of floral volatiles using a proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF-MS) and GC-MS. We also tested the effects of floral scent degradation on the responses of the generalist pollinator Bombus terrestris. The chemical analyses revealed that supplementing air with ozone led to an increasing reduction in the concentrations of floral volatiles in air with distance from the volatile source. The results revealed different reactivities with ozone for different floral scent constituents, which emphasized that ozone exposure not only degrades floral scents, but also changes the ratios of compounds in a scent blend. Behavioural tests revealed that floral scent was reduced in its attractiveness to pollinators after it had been exposed to 120 ppb O3 over a 4.5 m distance. The combined results of chemical analyses and behavioural responses of pollinators strongly suggest that high ozone concentrations have significant negative impacts on pollination by reducing the distance over which floral olfactory signals can be detected by pollinators. PMID:26346807

  2. Fate of products of degradation processes: consequences for climatic change.

    Science.gov (United States)

    Slanina, J; ten Brink, H M; Khlystov, A

    1999-03-01

    The end products of atmospheric degradation are not only CO2 and H2O but also sulfate and nitrate depending on the chemical composition of the substances which are subject to degradation processes. Atmospheric degradation has thus a direct influence on the radiative balance of the earth not only due to formation of greenhouse gases but also of aerosols. Aerosols of a diameter of 0.1 to 2 micrometer, reflect short wave sunlight very efficiently leading to a radiative forcing which is estimated to be about -0.8 watt per m2 by IPCC. Aerosols also influence the radiative balance by way of cloud formation. If more aerosols are present, clouds are formed with more and smaller droplets and these clouds have a higher albedo and are more stable compared to clouds with larger droplets. Not only sulfate, but also nitrate and polar organic compounds, formed as intermediates in degradation processes, contribute to this direct and indirect aerosol effect. Estimates for the Netherlands indicate a direct effect of -4 watt m-2 and an indirect effect of as large as -5 watt m-2. About one third is caused by sulfates, one third by nitrates and last third by polar organic compounds. This large radiative forcing is obviously non-uniform and depends on local conditions. PMID:10070730

  3. Phototransformation of amlodipine: degradation kinetics and identification of its photoproducts.

    Science.gov (United States)

    Jakimska, Anna; Śliwka-Kaszyńska, Magdalena; Nagórski, Piotr; Namieśnik, Jacek; Kot-Wasik, Agata

    2014-01-01

    Nowadays, monitoring focuses on the primary compounds and does not include degradation products formed during various biological and chemical processes. Transformation products may have the same effects to human health and the environment or sometimes they can be more toxic than the parent compound. Unfortunately, knowledge about the formation of degradation products is still limited, however, can be very important for the environmental risk assessment. Firstly, the photodegradation kinetic of amlodipine was investigated in two experimental conditions: during the exposure to solar radiation and during the exposure to the light emitted by the xenon lamp. In all cases degradation of amlodipine followed a pseudo-first-order kinetics. In the next step, identification of transformation products of amlodipine formed during the exposure to xenon lamp irradiation was performed using ultra high performance liquid chromatography quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS). As a result sixteen photoproducts were identified, their structures were elucidated and ultimately the transformation pathway was proposed. Fifteen compounds (out of 16 photoproducts) were newly identified and reported here for the first time; some of those compounds were formed from the first photoproduct, amlodipine pyridine derivative. Several analytes were formed only in acidic or basic conditions. Furthermore, the occurrence of amlodipine and its identified degradation products was investigated in environmental waters. Only one out of 16 compounds was found in wastewater effluent. The possibility of the sorption of examined analytes to sewage sludge particles was discussed based on QSAR. PMID:25279815

  4. Landform Degradation and Slope Processes on Io: The Galileo View

    Science.gov (United States)

    Moore, Jeffrey M.; Sullivan, Robert J.; Chuang, Frank C.; Head, James W., III; McEwen, Alfred S.; Milazzo, Moses P.; Nixon, Brian E.; Pappalardo, Robert T.; Schenk, Paul M.; Turtle, Elizabeth P.; DeVincenzi, Donald (Technical Monitor)

    2001-01-01

    The Galileo mission has revealed remarkable evidence of mass movement and landform degradation on Io. We recognize four major slope types observed on a number of intermediate resolution (250 m/pixel) images and several additional textures on very high resolution (10 m/pixel) images. Slopes and scarps on Io often show evidence of erosion, seen in the simplest form as alcove-carving slumps and slides at all scales. Many of the mass movement deposits on Io are probably mostly the consequence of block release and brittle slope failure. Sputtering plays no significant role. Sapping as envisioned by McCauley et al. remains viable. We speculate that alcove-lined canyons seen in one observation and lobed deposits seen along the bases of scarps in several locations may reflect the plastic deformation and 'glacial' flow of interstitial volatiles (e.g., SO2) heated by locally high geothermal energy to mobilize the volatile. The appearance of some slopes and near-slope surface textures seen in very high resolution images is consistent with erosion from sublimation-degradation. However, a suitable volatile (e.g., H2S) that can sublimate fast enough to alter Io's youthful surface has not been identified. Disaggregation from chemical decomposition of solid S2O and other polysulfur oxides may conceivably operate on Io. This mechanism could degrade landforms in a manner that resembles degradation from sublimation, and at a rate that can compete with resurfacing.

  5. Cariogenic bacteria degrade dental resin composites and adhesives.

    Science.gov (United States)

    Bourbia, M; Ma, D; Cvitkovitch, D G; Santerre, J P; Finer, Y

    2013-11-01

    A major reason for dental resin composite restoration replacement is related to secondary caries promoted by acid production from bacteria including Streptococcus mutans (S. mutans). We hypothesized that S. mutans has esterase activities that degrade dental resin composites and adhesives. Standardized specimens of resin composite (Z250), total-etch (Scotchbond Multipurpose, SB), and self-etch (Easybond, EB) adhesives were incubated with S. mutans UA159 or uninoculated culture medium (control) for up to 30 days. Quantification of the BisGMA-derived biodegradation by-product, bishydroxy-propoxy-phenyl-propane (BisHPPP), was performed by high-performance liquid chromatography. Surface analysis of the specimens was performed by scanning electron microscopy (SEM). S. mutans was shown to have esterase activities in levels comparable with those found in human saliva. A trend of increasing BisHPPP release throughout the incubation period was observed for all materials and was more elevated in the presence of bacteria vs. control medium for EB and Z250, but not for SB (p < .05). SEM confirmed the increased degradation of all materials with S. mutans UA159 vs. control. S. mutans has esterase activities at levels that degrade resin composites and adhesives; degree of degradation was dependent on the material's chemical formulation. This finding suggests that the resin-dentin interface could be compromised by oral bacteria that contribute to the progression of secondary caries.

  6. Phototransformation of amlodipine: degradation kinetics and identification of its photoproducts.

    Directory of Open Access Journals (Sweden)

    Anna Jakimska

    Full Text Available Nowadays, monitoring focuses on the primary compounds and does not include degradation products formed during various biological and chemical processes. Transformation products may have the same effects to human health and the environment or sometimes they can be more toxic than the parent compound. Unfortunately, knowledge about the formation of degradation products is still limited, however, can be very important for the environmental risk assessment. Firstly, the photodegradation kinetic of amlodipine was investigated in two experimental conditions: during the exposure to solar radiation and during the exposure to the light emitted by the xenon lamp. In all cases degradation of amlodipine followed a pseudo-first-order kinetics. In the next step, identification of transformation products of amlodipine formed during the exposure to xenon lamp irradiation was performed using ultra high performance liquid chromatography quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS. As a result sixteen photoproducts were identified, their structures were elucidated and ultimately the transformation pathway was proposed. Fifteen compounds (out of 16 photoproducts were newly identified and reported here for the first time; some of those compounds were formed from the first photoproduct, amlodipine pyridine derivative. Several analytes were formed only in acidic or basic conditions. Furthermore, the occurrence of amlodipine and its identified degradation products was investigated in environmental waters. Only one out of 16 compounds was found in wastewater effluent. The possibility of the sorption of examined analytes to sewage sludge particles was discussed based on QSAR.

  7. Modeling Degradation in Solid Oxide Electrolysis Cells - Volume II

    Energy Technology Data Exchange (ETDEWEB)

    Manohar Motwani

    2011-09-01

    Idaho National Laboratory has an ongoing project to generate hydrogen from steam using solid oxide electrolysis cells (SOECs). To accomplish this, technical and degradation issues associated with the SOECs will need to be addressed. This report covers various approaches being pursued to model degradation issues in SOECs. An electrochemical model for degradation of SOECs is presented. The model is based on concepts in local thermodynamic equilibrium in systems otherwise in global thermodynamic non-equilibrium. It is shown that electronic conduction through the electrolyte, however small, must be taken into account for determining local oxygen chemical potential,, within the electrolyte. The within the electrolyte may lie out of bounds in relation to values at the electrodes in the electrolyzer mode. Under certain conditions, high pressures can develop in the electrolyte just near the oxygen electrode/electrolyte interface, leading to oxygen electrode delamination. These predictions are in accordance with the reported literature on the subject. Development of high pressures may be avoided by introducing some electronic conduction in the electrolyte. By combining equilibrium thermodynamics, non-equilibrium (diffusion) modeling, and first-principles, atomic scale calculations were performed to understand the degradation mechanisms and provide practical recommendations on how to inhibit and/or completely mitigate them.

  8. Chemical carcinogenesis

    Directory of Open Access Journals (Sweden)

    Paula A. Oliveira

    2007-12-01

    Full Text Available The use of chemical compounds benefits society in a number of ways. Pesticides, for instance, enable foodstuffs to be produced in sufficient quantities to satisfy the needs of millions of people, a condition that has led to an increase in levels of life expectancy. Yet, at times, these benefits are offset by certain disadvantages, notably the toxic side effects of the chemical compounds used. Exposure to these compounds can have varying effects, ranging from instant death to a gradual process of chemical carcinogenesis. There are three stages involved in chemical carcinogenesis. These are defined as initiation, promotion and progression. Each of these stages is characterised by morphological and biochemical modifications and result from genetic and/or epigenetic alterations. These genetic modifications include: mutations in genes that control cell proliferation, cell death and DNA repair - i.e. mutations in proto-oncogenes and tumour suppressing genes. The epigenetic factors, also considered as being non-genetic in character, can also contribute to carcinogenesis via epigenetic mechanisms which silence gene expression. The control of responses to carcinogenesis through the application of several chemical, biochemical and biological techniques facilitates the identification of those basic mechanisms involved in neoplasic development. Experimental assays with laboratory animals, epidemiological studies and quick tests enable the identification of carcinogenic compounds, the dissection of many aspects of carcinogenesis, and the establishment of effective strategies to prevent the cancer which results from exposure to chemicals.A sociedade obtém numerosos benefícios da utilização de compostos químicos. A aplicação dos pesticidas, por exemplo, permitiu obter alimento em quantidade suficiente para satisfazer as necessidades alimentares de milhões de pessoas, condição relacionada com o aumento da esperança de vida. Os benefícios estão, por

  9. Chlorophenol Degradation Coupled to Sulfate Reduction

    OpenAIRE

    Häggblom, M M; Young, L. Y.

    1991-01-01

    We studied chlorophenol degradation under sulfate-reducing conditions with an estuarine sediment inoculum. These cultures degraded 0.1 mM 2-, 3-, and 4-chlorophenol and 2,4-dichlorophenol within 120 to 220 days, but after refeeding with chlorophenols degradation took place in 40 days or less. Further refeeding greatly enhanced the rate of degradation. Sulfate consumption by the cultures corresponded to the stoichiometric values expected for complete oxidation of the chlorophenol to CO2. Forma...

  10. Degradation of Chlorophyll Luminescence in Plants

    International Nuclear Information System (INIS)

    The chlorophyll photoluminescence intensity degradation of Vallisneria spiralis L. water plant is studied. It is shown that the degradation curve is rather well described by a sum of two hyperbolic functions. The rate of intensity degradation reduces at low temperatures. At room temperature, a slow restoration of the luminescent system is observed after the irradiation has been ceased. No restoration is detected at the liquid nitrogen temperature. A simplified model which describes the luminescence degradation according to the quadratic law is suggested.

  11. Economics of land degradation in Eastern Africa

    OpenAIRE

    Kirui, Oliver Kiptoo; Mirzabaev, Alisher

    2014-01-01

    Land degradation remains a serious impediment to improving livelihoods in the Eastern Africa region. This working paper presents a general overview of the state and extent of land degradation in East Africa, explores its proximate and underlying drivers, identifies the land degradation hotspots in the region, and also discusses the productivity and poverty impacts of land degradation in the region. It is intended to serve as an exploratory tool for the ensuing more detailed quantitative analy...

  12. Biological degradation of petroleum hydrocarbons in the Northsea with special reference to component difficult to biodegrade and useful as key compounds for marine environmental monitoring by chemical analysis. Biologischer Abbau von Erdoelkohlenwasserstoffen in der Nordsee unter besonderer Beruecksichtigung von schwer abbaubaren Komponenten, die als Leitsubstanzen fuer die chemisch analytische Ueberwachung der Meeresumwelt dienen sollen

    Energy Technology Data Exchange (ETDEWEB)

    Bruns, K.; Gunkel, W. (Biologische Anstalt Helgoland (Germany, F.R.). Meeresstation); Dahlmann, G.; Theobald, N. (Deutsches Hydrographisches Inst., Hamburg (Germany, F.R.). Lab. Suelldorf)

    1989-01-01

    Supplemented degradation tests of petroleum by marine bacteria in batch culture were analysed by gas chromatography and combined gas chromatography and mass spectroscopy. The results show a variety of effects produced by the different nutrient salts concentrations and combinations with trace elements. The known supplementation of microbial oil degradation by nitrogen and phosphorus is greatly enhanced in its effectiveness by the addition of trace elements. Even those oil components which are known to be resistant to biodegradation, will be attacked when incubated with low concentrations of nitrogen and phosphorus (0.01 NP or P 4xN) and trace elements; pyrene and methyl dibenzothiophenes, for instance, were reduced by 40 to 50% after 6 week incubation. An optimal composition resulting in optimal biodegradation in any of the oils studied, was not found. The findings suggest that the biodegradation of specific petroleum hydrocarbons is determined by the composition and concentration of the supplementation used. (orig.).

  13. Chemical cosmology

    CERN Document Server

    Boeyens, Jan CA

    2010-01-01

    The composition of the most remote objects brought into view by the Hubble telescope can no longer be reconciled with the nucleogenesis of standard cosmology and the alternative explanation, in terms of the LAMBDA-Cold-Dark-Matter model, has no recognizable chemical basis. A more rational scheme, based on the chemistry and periodicity of atomic matter, opens up an exciting new interpretation of the cosmos in terms of projective geometry and general relativity. The response of atomic structure to environmental pressure predicts non-Doppler cosmical redshifts and equilibrium nucleogenesis by alp

  14. Chemical Sensing for Buried Landmines - Fundamental Processes Influencing Trace Chemical Detection

    Energy Technology Data Exchange (ETDEWEB)

    PHELAN, JAMES M.

    2002-05-01

    Mine detection dogs have a demonstrated capability to locate hidden objects by trace chemical detection. Because of this capability, demining activities frequently employ mine detection dogs to locate individual buried landmines or for area reduction. The conditions appropriate for use of mine detection dogs are only beginning to emerge through diligent research that combines dog selection/training, the environmental conditions that impact landmine signature chemical vapors, and vapor sensing performance capability and reliability. This report seeks to address the fundamental soil-chemical interactions, driven by local weather history, that influence the availability of chemical for trace chemical detection. The processes evaluated include: landmine chemical emissions to the soil, chemical distribution in soils, chemical degradation in soils, and weather and chemical transport in soils. Simulation modeling is presented as a method to evaluate the complex interdependencies among these various processes and to establish conditions appropriate for trace chemical detection. Results from chemical analyses on soil samples obtained adjacent to landmines are presented and demonstrate the ultra-trace nature of these residues. Lastly, initial measurements of the vapor sensing performance of mine detection dogs demonstrates the extreme sensitivity of dogs in sensing landmine signature chemicals; however, reliability at these ultra-trace vapor concentrations still needs to be determined. Through this compilation, additional work is suggested that will fill in data gaps to improve the utility of trace chemical detection.

  15. Chemical compatibility of cartridge materials

    Science.gov (United States)

    Ambrose, Bryan; Wilcox, R. C.; Zee, R. H.

    1992-01-01

    The objectives were to determine the chemical compatibility of titanium-zirconium-molybdenum (TZM) with GaAs and CdZnTe, and Inconel with HgCdTe and HgZnTe. At the present time, no other studies regarding the compatibility of these crystal components and their respective cartridge materials have been performed. This study was to identify any possible problems between these materials to insure proper containment of possibly hazardous fumes during crystal growth experiments. In this study, the reaction zone between the materials was studied and the amount of degradation to the system was measured. Detailed results are presented.

  16. Applications and extensions of degradation modeling

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, F.; Subudhi, M.; Samanta, P.K. (Brookhaven National Lab., Upton, NY (United States)); Vesely, W.E. (Science Applications International Corp., Columbus, OH (United States))

    1991-01-01

    Component degradation modeling being developed to understand the aging process can have many applications with potential advantages. Previous work has focused on developing the basic concepts and mathematical development of a simple degradation model. Using this simple model, times of degradations and failures occurrences were analyzed for standby components to detect indications of aging and to infer the effectiveness of maintenance in preventing age-related degradations from transforming to failures. Degradation modeling approaches can have broader applications in aging studies and in this paper, we discuss some of the extensions and applications of degradation modeling. The application and extension of degradation modeling approaches, presented in this paper, cover two aspects: (1) application to a continuously operating component, and (2) extension of the approach to analyze degradation-failure rate relationship. The application of the modeling approach to a continuously operating component (namely, air compressors) shows the usefulness of this approach in studying aging effects and the role of maintenance in this type component. In this case, aging effects in air compressors are demonstrated by the increase in both the degradation and failure rate and the faster increase in the failure rate compared to the degradation rate shows the ineffectiveness of the existing maintenance practices. Degradation-failure rate relationship was analyzed using data from residual heat removal system pumps. A simple linear model with a time-lag between these two parameters was studied. The application in this case showed a time-lag of 2 years for degradations to affect failure occurrences. 2 refs.

  17. Applications and extensions of degradation modeling

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, F.; Subudhi, M.; Samanta, P.K. [Brookhaven National Lab., Upton, NY (United States); Vesely, W.E. [Science Applications International Corp., Columbus, OH (United States)

    1991-12-31

    Component degradation modeling being developed to understand the aging process can have many applications with potential advantages. Previous work has focused on developing the basic concepts and mathematical development of a simple degradation model. Using this simple model, times of degradations and failures occurrences were analyzed for standby components to detect indications of aging and to infer the effectiveness of maintenance in preventing age-related degradations from transforming to failures. Degradation modeling approaches can have broader applications in aging studies and in this paper, we discuss some of the extensions and applications of degradation modeling. The application and extension of degradation modeling approaches, presented in this paper, cover two aspects: (1) application to a continuously operating component, and (2) extension of the approach to analyze degradation-failure rate relationship. The application of the modeling approach to a continuously operating component (namely, air compressors) shows the usefulness of this approach in studying aging effects and the role of maintenance in this type component. In this case, aging effects in air compressors are demonstrated by the increase in both the degradation and failure rate and the faster increase in the failure rate compared to the degradation rate shows the ineffectiveness of the existing maintenance practices. Degradation-failure rate relationship was analyzed using data from residual heat removal system pumps. A simple linear model with a time-lag between these two parameters was studied. The application in this case showed a time-lag of 2 years for degradations to affect failure occurrences. 2 refs.

  18. Degradation analysis of thin film photovoltaic modules

    Energy Technology Data Exchange (ETDEWEB)

    Radue, C., E-mail: chantelle.radue@nmmu.ac.z [Department of Physics, PO Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa); Dyk, E.E. van [Department of Physics, PO Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa)

    2009-12-01

    Five thin film photovoltaic modules were deployed outdoors under open circuit conditions after a thorough indoor evaluation. Two technology types were investigated: amorphous silicon (a-Si:H) and copper indium gallium diselenide (CIGS). Two 14 W a-Si:H modules, labelled Si-1 and Si-2, were investigated. Both exhibited degradation, initially due to the well-known light-induced degradation described by Staebler and Wronski [Applied Physics Letters 31 (4) (1977) 292], and thereafter due to other degradation modes such as cell degradation. The various degradation modes contributing to the degradation of the a-Si:H modules will be discussed. The initial maximum power output (P{sub MAX}) of Si-1 was 9.92 W, with the initial light-induced degradation for Si-1 approx30% and a total degradation of approx42%. For Si-2 the initial P{sub MAX} was 7.93 W, with initial light-induced degradation of approx10% and a total degradation of approx17%. Three CIGS modules were investigated: two 20 W modules labelled CIGS-1 and CIGS-2, and a 40 W module labelled CIGS-3. CIGS-2 exhibited stable performance while CIGS-1 and CIGS-3 exhibited degradation. CIGS is known to be stable over long periods of time, and thus the possible reasons for the degradation of the two modules are discussed.

  19. Polylactide Degradation by an Amycolatopsis sp

    OpenAIRE

    Pranamuda, H.; Tokiwa, Y.; Tanaka, H.

    1997-01-01

    By applying the plate count and clear-zone methods, it was confirmed that polylactide (PLA)-degrading microorganisms are sparsely distributed in soil environments. An Amycolatopsis isolate was successfully isolated. Microbial degradation of PLA film was demonstrated; i.e., about 60% of the 100-mg film initially added was degraded by the strain after 14 days of liquid culture.

  20. Degradation analysis of thin film photovoltaic modules

    International Nuclear Information System (INIS)

    Five thin film photovoltaic modules were deployed outdoors under open circuit conditions after a thorough indoor evaluation. Two technology types were investigated: amorphous silicon (a-Si:H) and copper indium gallium diselenide (CIGS). Two 14 W a-Si:H modules, labelled Si-1 and Si-2, were investigated. Both exhibited degradation, initially due to the well-known light-induced degradation described by Staebler and Wronski [Applied Physics Letters 31 (4) (1977) 292], and thereafter due to other degradation modes such as cell degradation. The various degradation modes contributing to the degradation of the a-Si:H modules will be discussed. The initial maximum power output (PMAX) of Si-1 was 9.92 W, with the initial light-induced degradation for Si-1 ∼30% and a total degradation of ∼42%. For Si-2 the initial PMAX was 7.93 W, with initial light-induced degradation of ∼10% and a total degradation of ∼17%. Three CIGS modules were investigated: two 20 W modules labelled CIGS-1 and CIGS-2, and a 40 W module labelled CIGS-3. CIGS-2 exhibited stable performance while CIGS-1 and CIGS-3 exhibited degradation. CIGS is known to be stable over long periods of time, and thus the possible reasons for the degradation of the two modules are discussed.

  1. Nylon biodegradation by lignin-degrading fungi.

    OpenAIRE

    DEGUCHI, T; Kakezawa, M; Nishida, T.

    1997-01-01

    The biodegradation of nylon by lignin-degrading fungi was investigated. The fungus IZU-154 significantly degraded nylon-66 membrane under ligninolytic conditions. Nuclear magnetic resonance analysis showed that four end groups, CHO, NHCHO, CH3, and CONH2, were formed in the biodegraded nylon-66 membranes, suggesting that nylon-66 was degraded oxidatively.

  2. Isolation of a Pseudomonas Stutzeri strain that degrades1, 2, 4-trichlorobenzene and characterization of its degradative plasmid

    Institute of Scientific and Technical Information of China (English)

    Lei SONG; Hui WANG; Hanchang SHI; Hongying HU

    2008-01-01

    The genetic information encoding metabolic pathways for xenobiotic compounds in bacteria often resides on catabolic plasmids. The aim of the present work was to know the location of the genes for degrading 1, 2, 4-trichlorobenzen. In this paper a 1, 2, 4-trichlorobenzene-degrading strain THSL-1 was isolated from the soil of Tianjin Chemical Plant using 1, 2, 4-trichlorobenzene as the sole carbon source. The strain was identified as Pseudomonas stutzeri through morphologic survey and 16S rDNA sequence determination. A plasmid was discovered from strain THSL-1 by using the alkali lysis method. When the plasmid was transformed into E. coli. JM109 by the CaCl2 method, the transformant could grow using 1, 2, 4-trichlorobenzene as the sole carbon source and had the degradation function of 1, 2, 4-trichlorobenzene. Therefore, it could be deemed that the plasmid carried the degradative genes of 1, 2, 4-trichlorobenzene. The average size of the plasmid was finally determined to be 40.2 Kb using selectively three kinds of restricted inscribed enzymes (HindIII, BamHI, and XholI) for single cutting and double cutting the plasmid pTHSL-1, respectively.

  3. Chemical spectroscopy

    International Nuclear Information System (INIS)

    The purpose of chemical spectroscopy with neutrons is to utilize the dependence of neutron scattering cross-sections on isotope and on momentum transfer (which probes the spatial extent of the excitation) to understand fundamental and applied aspects of the dynamics of molecules and fluids. Chemical spectroscopy is divided into three energy ranges: vibrational spectroscopy, 25-500 MeV, for which much of the work is done on Be-filter analyzer instruments; low energy spectroscopy, less than 25 MeV; and high resolution spectroscopy, less than 1 MeV, which typically is performed on backscattering spectrometers. Representative examples of measurements of the Q-depenence of vibrational spectra, higher energy resolution as well as extension of the Q-range to lower values at high energy transfers, and provisions of higher sensitivities in vibrational spectroscopy are discussed. High resolution, high sensitivity, and polarization analysis studies in low energy spectroscopy are discussed. Applications of very high resolution spectroscopy are also discussed

  4. [It is imperative to stop environmental degradation].

    Science.gov (United States)

    Leff, E

    1990-01-01

    Environmental demography deals with socioenvironmental determinants of demographic processes. The fertility decline of recent years in Mexico is not associated with economic transformation, as the economic crisis, poverty, unemployment, and social inequality have been barely mitigated. Mexico is mainly urban: 51% of the population lived in cities with more than 100,000 inhabitants in 1990 taking an increasing toll on the environment. The metropolitan area of Mexico City has 50% of industrial production with 36,000 industrial plants, 2100 of all 5400 chemical plants, 22% of total population, and 25% of economically active population. There are 3 million cars. 11,000 tons of solid waste is generated daily (75% domestic and 25% industrial), and 5 million tons of contaminants are emitted annually. Sulphur, dioxide, nitrogen, ozone, and suspended particulate levels often exceed international standards. In the federal district more than 1000 squatter colonies are without drainage that affects 5 million people; and 30% of the population is without a sewage network. There are 35 cities with over 100,000 population that cannot meet their needs of drinking water with the result of a high level of gastrointestinal ailments, enteritis, diarrhea, rabies, and dengue fever caused by pathogenic microorganisms, the major cause of mortality. The degradation of the environment produces a pathological environmental emergency from chemical contamination of the air and from exposure to industrial emissions, to agrochemical products and toxic substances, to lead, insecticides, arsenic, and asbestos. Mexico has one of the highest levels of lead in the blood and DDT in mother's milk. In Mexico City lead concentration of 5 mg/cubic meter in the air, 20 mg/100 ml in maternal blood, and 13 mg/100 ml in the umbilical cord was detected associated with retardation of mental development in the 1st year of life and chronic lead poisoning. PMID:12158050

  5. Reduce land degradation, climate change and adaptation measures

    International Nuclear Information System (INIS)

    The land degradation and desertification are a serious threat to the sustainability of production food in many areas of the Earth. the methods ecosystems and the concomitant effects management of climate change are altering the processes physical, chemical and biological processes that regulate the complex balance of terrestrial ecosystems and soil particularly in areas climatically characterized by conditions arid, semi-arid and dry sub humid areas. The RIO + 20 Conference has recognized the risk of desertification and it proposed for the post 2015 agenda the goal of a world 'Land Degradation Neutral'.The challenge of adaptation to changes climate will require a greater involvement scientific research in support of conservation and use of natural resources both in Italy and in all contexts where the challenge of sustainability of development is more urgent.

  6. Glow Discharge Induced Hydroxyl Radical Degradation of 2-Naphthylamine

    Institute of Scientific and Technical Information of China (English)

    Lu Quanfang; Yu Jie; Gao Jinzhang; Yang Wu

    2005-01-01

    In an aqueous solution, normal electrolysis at high voltages switches over sponta-neously to glow discharge electrolysis and gives rise to hydroxyl radical, hydrogen peroxide, andaqueous electron, as well as several other active species. Hydroxyl radical directly attacks or-ganic contaminants to make them oxidized. In the present paper, 2-naphthylamine is eventuallydegraded into hydrogen carbonate and carbon dioxide. The degradation process is analyzed byusing an Ultraviolet (UV) absorption spectrum, high-performance liquid chromatography (HPLC)and chemical oxygen demand (COD). It is demonstrated that 2-naphthylamine (c0 =30 mg.1-1) iscompletely converted within 2h at 30℃ and 600 V by glow discharge electrolysis, and the degra-dation is strongly dependent upon the presence of ferrous ions. COD is ascended in the absenceof ferrous ions and descended in the presence of them.

  7. Geospatial tools for assessing land degradation in Budgam district, Kashmir Himalaya, India

    Science.gov (United States)

    Rashid, Mehnaz; Lone, Mahjoor Ahmad; Romshoo, Shakil Ahmad

    2011-06-01

    Land degradation reduces the ability of the land to perform many biophysical and chemical functions. The main aim of this study was to determine the status of land degradation in the Budgam area of Kashmir Himalaya using remote sensing and geographic information system. The satellite data together with other geospatial datasets were used to quantify different categories of land degradation. The results were validated in the field and an accuracy of 85% was observed. Land use/land cover of the study area was determined in order to know the effect of land use on the rate of land degradation. Normalized differential vegetation index (NDVI) and slope of the area were determined using LANDSAT-enhanced thematic mapper plus (ETM+) data, advanced space borne thermal emission and reflection radiometer, and digital elevation model along with other secondary data were analysed to create various thematic maps, viz., land use/land cover, geology, NDVI and slopes used in modelling land degradation in the Kashmir Himalayan region. The vegetation condition, elevation and land use/land cover information of the area were integrated to assess the land degradation scenario in the area using the ArcGIS `Spatial Analyst Module'. The results reveal that about 13.19% of the study area has undergone moderate to high degradation, whereas about 44.12% of the area has undergone slight degradation.

  8. Electrochemical Degradation of o-Chloronitrobenzene by Three-dimensional Electrodes

    Institute of Scientific and Technical Information of China (English)

    MENG Qing-han; WANG Jing; LIU Ling; CAO Bing

    2012-01-01

    Degradation of o-chloronitrobenzene wastewater was experimentally investigated at a three-dimensional electrode(TDE) with granular activated carbon as the particle electrode,graphite as the anode,and stainless steel plate as the cathode.The kinetic model of o-chloronitrobenzene degradation was studied,and the effects of pH,electrolysis time,particle electrode,electrolyte concentration,and initial concentration of the solution on degradation efficiency were investigated to determine the optimal operating conditions.The degradation of o-chloronitrobenzene by oxidation at the TDE was monitored by chemical oxygen demand(COD) measurements,UV-Vis absorption,and high performance liquid chromatography(HPLC).COD degradation by electrochemical degradation followed pseudo-first order kinetics with respect to the concentration of o-chloronitrobenzene solutions.Optimal reaction conditions included 15 g of activated carbon as the particle electrode,400 mg/L o-chloronitrobenzene solution containing 0.10 mol/L Na2SO4,pH=3,and 60 min of electrolysis.The UV-Vis absorption spectra and HPLC results illustrate that the benzene ring in o-chloronitrobenzene was rapidly broken down to form aliphatic substances through electrochemical degradation.COD degradation was approximately 98.5% at optimal conditions.

  9. Sonochemical degradation of naphthol blue black in water: Effect of operating parameters.

    Science.gov (United States)

    Ferkous, Hamza; Hamdaoui, Oualid; Merouani, Slimane

    2015-09-01

    In this work, the sonochemical degradation of naphthol blue black (NBB), an acidic diazo dye, in water was investigated. The effects of several operating parameters such as initial NBB concentration, acoustic intensity, ultrasonic frequency, nature of the dissolved gas and solution pH on the degradation of the dye were carried out. The obtained results showed that ultrasound completely destroyed NBB (5 mg L(-1)) after 45 min of sonication and most of the chemical oxygen demand was eliminated after 90 min of treatment. It was found that the initial rate of sonolytic degradation increased with increasing the initial NBB concentration. The fitting of the experimental data by a heterogeneous Langmuir-kinetics model showed that NBB degraded mainly at the interfacial region of the bubble by hydroxyl radical (OH) attack. The degradation rate of the dye increased substantially with increasing acoustic intensity in the range of 0.44-3.58 W cm(-2) and decreased with increasing frequency in the range of 585-1140 kHz. The rate of NBB degradation decreased in the order of Ar>air>N2. The significant degradation was achieved in acidic conditions (pH 2) where the initial degradation rate was 1.37 and 1.66 higher than those observed at pH 6 and pH 10, respectively. PMID:25843901

  10. Geospatial tools for assessing land degradation in Budgam district, Kashmir Himalaya, India

    Indian Academy of Sciences (India)

    Mehnaz Rashid; Mahjoor Ahmad Lone; Shakil Ahmad Romshoo

    2011-06-01

    Land degradation reduces the ability of the land to perform many biophysical and chemical functions. The main aim of this study was to determine the status of land degradation in the Budgam area of Kashmir Himalaya using remote sensing and geographic information system. The satellite data together with other geospatial datasets were used to quantify different categories of land degradation. The results were validated in the field and an accuracy of 85% was observed. Land use/land cover of the study area was determined in order to know the effect of land use on the rate of land degradation. Normalized differential vegetation index (NDVI) and slope of the area were determined using LANDSAT-enhanced thematic mapper plus (ETM+) data, advanced space-borne thermal emission and reflection radiometer, and digital elevation model along with other secondary data were analysed to create various thematic maps, viz., land use/land cover, geology, NDVI and slopes used in modelling land degradation in the Kashmir Himalayan region. The vegetation condition, elevation and land use/land cover information of the area were integrated to assess the land degradation scenario in the area using the ArcGIS ‘Spatial Analyst Module’. The results reveal that about 13.19% of the study area has undergone moderate to high degradation, whereas about 44.12% of the area has undergone slight degradation.

  11. Optical transmittance degradation in tapered fibers

    CERN Document Server

    Fujiwara, Masazumi; Takeuchi, Shigeki

    2012-01-01

    We investigated the cause of optical transmittance degradation in tapered fibers. Degradation commences immediately after fabrication and it eventually reduces the transmittance to almost zero. It is a major problem that limits applications of tapered fibers. We systematically investigated the effect of the dust-particle density and the humidity on the degradation dynamics. The results clearly show that the degradation is mostly due to dust particles and that it is not related to the humidity. In a dust free environment it is possible to preserve the transmittance with a degradation of less than the noise (+/- ?0.02) over 1 week.

  12. The effects and mode of action of biochar on the degradation of methyl isothiocyanate in soil.

    Science.gov (United States)

    Fang, Wensheng; Wang, Qiuxia; Han, Dawei; Liu, Pengfei; Huang, Bin; Yan, Dongdong; Ouyang, Canbin; Li, Yuan; Cao, Aocheng

    2016-09-15

    Biochar is used as a new type of fertilizer in agriculture; however, its effect on the fate of fumigants in soil is not fully understood. The objective of this study was to investigate the effects of biochar on methyl isothiocyanate (MITC) degradation in soil in laboratory incubation experiments, including the effects of biochar composition, amendment rate, moisture, temperature, soil sterilization and soil type. The dissipation pathways of MITC in biochars included adsorption and chemical degradation. The adsorption of MITC by biochars was positively correlated with the specific surface area (SSA) of the biochar. Biochar with a high SSA and low H/C value (such as biochar type BC-1) reduced MITC degradation in soil substantially; following BC-1 amendment, the degradation rate was 73.9% slower than in unamended soil. The degradation of MITC was positively correlated with the H/C value of biochar, and MITC degradation in soil increased 2.2-31.1 times following amendment with biochars with higher H/C values (e.g. biochar types BC-3-6). The biochar with the lowest organic matter and low H/C value did not affect the fate of MITC in soil. Biochars affect abiotic degradation processes more than biodegradation. When soil samples had a higher water content (>10%), higher temperature (40°C), and lower organic matter, the addition of BC-1 biochar reduced MITC degradation substantially; and this did not change significantly when the amendment rate increased. However, BC-4 biochar accelerated MITC degradation with increasing amendment rate, increasing temperature, and decreasing soil water content. The differences in degradation rates due to soil type were minimized by amendment with BC-4, but significant differences in BC-1. The results showed that the rational use of biochar has the potential to reduce MITC emission by accelerated degradation and adsorption. PMID:27177140

  13. Radiation degradation of spent butyl rubbers

    Science.gov (United States)

    Telnov, A. V.; Zavyalov, N. V.; Khokhlov, Yu. A.; Sitnikov, N. P.; Smetanin, M. L.; Tarantasov, V. P.; Shadrin, D. N.; Shorikov, I. V.; Liakumovich, A. L.; Miryasova, F. K.

    2002-03-01

    Radiation methods of materials modification applied in technological chains can have significant economical and ecological advantages as compared to the established chemical, thermal and mechanical methods. Each year the problems of nature resources economy through the use of production and consumption wastes acquire a more significant value, as it allows to solve also ecological issues along with economical ones. This is mostly acute in relation to polymeric systems based on saturated rubbers, for example butyl rubber (BR) used in the tyre industry, as due to their high resistance to the action of oxygen, ozone, solar radiation and bacteria, they contaminate the environment for rather a long period. At VNIIEF and KSPU experiments were carried out on application of electron beams with energy from 6 to 10 MeV for radiation destruction of spent rubber based on BR. The radiation-degraded material was tested for re-use in the formulation of initial diaphragm mixture, rubber mixture for producing rubberized fabric and roofing.

  14. Degradation of Green Polyethylene by Pleurotus ostreatus.

    Science.gov (United States)

    da Luz, José Maria Rodrigues; Paes, Sirlaine Albino; Ribeiro, Karla Veloso Gonçalves; Mendes, Igor Rodrigues; Kasuya, Maria Catarina Megumi

    2015-01-01

    We studied the biodegradation of green polyethylene (GP) by Pleurotus ostreatus. The GP was developed from renewable raw materials to help to reduce the emissions of greenhouse gases. However, little information regarding the biodegradation of GP discarded in the environment is available. P. ostreatus is a lignocellulolytic fungus that has been used in bioremediation processes for agroindustrial residues, pollutants, and recalcitrant compounds. Recently, we showed the potential of this fungus to degrade oxo-biodegradable polyethylene. GP plastic bags were exposed to sunlight for up to 120 days to induce the initial photodegradation of the polymers. After this period, no cracks, pits, or new functional groups in the structure of GP were observed. Fragments of these bags were used as the substrate for the growth of P. ostreatus. After 30 d of incubation, physical and chemical alterations in the structure of GP were observed. We conclude that the exposure of GP to sunlight and its subsequent incubation in the presence of P. ostreatus can decrease the half-life of GP and facilitate the mineralization of these polymers. PMID:26076188

  15. Degradation of Green Polyethylene by Pleurotus ostreatus.

    Directory of Open Access Journals (Sweden)

    José Maria Rodrigues da Luz

    Full Text Available We studied the biodegradation of green polyethylene (GP by Pleurotus ostreatus. The GP was developed from renewable raw materials to help to reduce the emissions of greenhouse gases. However, little information regarding the biodegradation of GP discarded in the environment is available. P. ostreatus is a lignocellulolytic fungus that has been used in bioremediation processes for agroindustrial residues, pollutants, and recalcitrant compounds. Recently, we showed the potential of this fungus to degrade oxo-biodegradable polyethylene. GP plastic bags were exposed to sunlight for up to 120 days to induce the initial photodegradation of the polymers. After this period, no cracks, pits, or new functional groups in the structure of GP were observed. Fragments of these bags were used as the substrate for the growth of P. ostreatus. After 30 d of incubation, physical and chemical alterations in the structure of GP were observed. We conclude that the exposure of GP to sunlight and its subsequent incubation in the presence of P. ostreatus can decrease the half-life of GP and facilitate the mineralization of these polymers.

  16. Transport and degradation of propyleneglycol and potassium acetate in the unsaturated zone

    Science.gov (United States)

    French, H. K.; Van der Zee, S. E. A. T. M.; Leijnse, A.

    2001-05-01

    De-icing chemicals used during the winter season are potential pollutants for the groundwater underneath the new main airport of Norway. Several field experiments examining the transport and degradation of propyleneglycol (PG), potassium acetate (KAc) and non-reactive tracers were performed in a lysimeter trench under natural snowmelting conditions. Chemicals were applied underneath the snow cover and the transport in a heterogeneous coarse sandy soil was examined by extracting soil water from 30 or 40 suction cups placed at five depths between 0.4 and 2.4 m depth. Transport and degradation was analysed by spatial moment calculations. The de-icing chemicals showed the same basic displacement as chemically inactive tracers, an initial fast transport during the melting period followed by a period of stagnation throughout the summer season. PG seemed to be displaced to greater depths compared to non-reactive tracer after the first application. However, computer simulations of transport and degradation in a heterogeneous unsaturated soil showed that decreasing degradation constants with depth can generate a downward movement of the centre of mass without any flow occurring in the system. Potassium acetate showed some adsorption, with calculated retardation factors of approximately 1.3 and 1.2. The degradation rate constant for PG was calculated to be 0.015 day -1 in 1994 and increased to 0.047 day -1 in the second application made in 1995. The degradation rate constant for acetate was estimated to be 0.02 day -1. Increased manganese concentrations seem to be a good indicator of degradation of PG and Ac.

  17. Starch-degrading polysaccharide monooxygenases.

    Science.gov (United States)

    Vu, Van V; Marletta, Michael A

    2016-07-01

    Polysaccharide degradation by hydrolytic enzymes glycoside hydrolases (GHs) is well known. More recently, polysaccharide monooxygenases (PMOs, also known as lytic PMOs or LPMOs) were found to oxidatively degrade various polysaccharides via a copper-dependent hydroxylation. PMOs were previously thought to be either GHs or carbohydrate binding modules (CBMs), and have been re-classified in carbohydrate active enzymes (CAZY) database as auxiliary activity (AA) families. These enzymes include cellulose-active fungal PMOs (AA9, formerly GH61), chitin- and cellulose-active bacterial PMOs (AA10, formerly CBM33), and chitin-active fungal PMOs (AA11). These PMOs significantly boost the activity of GHs under industrially relevant conditions, and thus have great potential in the biomass-based biofuel industry. PMOs that act on starch are the latest PMOs discovered (AA13), which has expanded our perspectives in PMOs studies and starch degradation. Starch-active PMOs have many common structural features and biochemical properties of the PMO superfamily, yet differ from other PMO families in several important aspects. These differences likely correlate, at least in part, to the differences in primary and higher order structures of starch and cellulose, and chitin. In this review we will discuss the discovery, structural features, biochemical and biophysical properties, and possible biological functions of starch-active PMOs, as well as their potential application in the biofuel, food, and other starch-based industries. Important questions regarding various aspects of starch-active PMOs and possible economical driving force for their future studies will also be highlighted. PMID:27170366

  18. Degrading and Detoxifying Industrial Waste Water using Bioremediation Approach

    Directory of Open Access Journals (Sweden)

    P. K. Agrawal

    2014-06-01

    Full Text Available Bioremediation uses various microorganisms to detoxify or degrade various harmful substances in the nature, particularly soil and water. In the proposed work, five species of micro-organisms were used to analyse their impact on various physico-chemical parameters of water. In the first attempt the actual physico chemical parameters of the collected sample water were noted down (Fresh sample parameters. Then the sample water was treated with micro-organisms (one at a time. The growth of microbes was noted carefully over 96 hours after inoculation. The physico chemical parameters were recorded again and were compared with the fresh sample parameters. The results were analysed for any change and on this basis an impact factor was developed. The study reveals all the selected microbes have a great capacity of degrading and simplifying the complex molecules into simpler ones. Bioremediative treatment further enhances this capacity and therefore this approach can be utilized on large scale to minimize pollution of water bodies.

  19. Managing livestock in degrading environments

    International Nuclear Information System (INIS)

    Degraded environments are both widespread (being found on all continents on earth) and diverse. They have been broadly classified as: irrigated (and rain-fed) farmland with elevated water tables causing salinity; rain-fed farmland with soil erosion, loss of organic matter, nutrient depletion and weed invasion; and degraded rangeland. This review considers all these but with a focus on the first two, and particularly addresses options for simultaneous improvement in livestock production and landscape health. There is evidence that responsible grazing is consistent with ecosystem benefits and resilient land use systems; exclusion from grazing may reduce diversity and create management complexity. Responsible grazing however will only prevail if the land owner or user receives a financial benefit in the process. Solutions need to be profitable. In the development and management of grazing systems, expectations need to be realistic. The prescriptive approach to livestock feeding based on the selection and cultivation of a small range of improved plant species to meet predetermined energy, protein and mineral requirements is inappropriate. Degraded landscapes are often associated with a high edaphic and climatic variability that is best suited to a diverse range of plant species in an assembly that will fluctuate over time and space. This diversity means that under some circumstances degraded land may contribute to reduced risk within a whole farm business. Simultaneous objectives for livestock and landscape improvement may or may not contribute to the return of the landscape to its original state. In some cases stable vegetation that provides some of the functional benefits of the original landscape, such as improved biodiversity and soil health, combined with production benefits is the best option available. This provides an opportunity to establish a range of objectives in vegetation management and design. In Australia, such an approach is leading to the development

  20. Permafrost degradation in West Greenland

    DEFF Research Database (Denmark)

    Foged, Niels Nielsen; Ingeman-Nielsen, Thomas

    2012-01-01

    and the first author has been involved since 1970 in engineering geology, geotechnical engineering and permafrost related studies for foundation construction and infrastructures in towns and communities mainly in West Greenland. We have since 2006 together with the Danish Meteorological Institute, Greenland...... Survey (ASIAQ) and the University of Alaska Fairbanks carried out the US NSF funded project ARC-0612533: Recent and future permafrost variability, retreat and degradation in Greenland and Alaska: An integrated approach. This contribution will present data and observations from the towns Ilulissat...

  1. Managing livestock in degrading environments

    International Nuclear Information System (INIS)

    While overgrazing is often blamed for environmental degradation, there is clear evidence that livestock are not inherently damaging to rangelands or farming landscapes, and, in fact, may be required for their sustained health and profitability. Moderate to heavy grazing has, in some cases created highly resilient and ecologically sound systems while under-grazing has resulted in dense woody growth and reduced species diversity. Conversion of rangelands into intensive crop/fodder production has also led to progressive loss of diversity, species connectivity and ability to recover. Well-managed livestock in either a grassland or mixed crop/livestock system offer a highly efficient method of increasing the production of high quality food with minimal environmental impact. Although an ecological case can be established for the continued use of livestock in degrading landscapes, the reality is, livestock will only be grazed responsibly if the owner receives a benefit from the process. Importantly, by providing a potentially profitable option, the revegetation of degraded or partly degraded landscapes may take place through the expenditure of private rather than public funding. Given the vastness of the landscapes in question and the urban priorities in the expenditure of public funds, significant progress is only likely if profitable solutions are available. This use of livestock may or may not contribute to the return of the landscape to its original state. In some cases stable vegetation that provides some of the functional benefits of the original landscape, combined with the productive benefits of a profitable livestock system may be the best option available. This then provides an opportunity to design a landscape based on a range of predetermined objectives which include both profit and ecosystem services. For example, in Western Australia, the revegetation of 10% of the 1 million ha of saline land with halophytic shrubs and salt tolerant forage has resulted in a

  2. Chemical intolerance

    DEFF Research Database (Denmark)

    Dantoft, Thomas Meinertz; Andersson, Linus; Nordin, Steven;

    2015-01-01

    are available, the presence of the condition can only be established in accordance to criteria definitions. Numerous modes of action have been suggested to explain CI, with the most commonly discussed theories involving the immune system, central nervous system, olfactory and respiratory systems as well...... chemical sensitivity (MCS). The symptoms reported by CI subjects are manifold, involving symptoms from multiple organs systems. In severe cases of CI, the condition can cause considerable life-style limitations with severe social, occupational and economic consequences. As no diagnostic tools for CI...... or offered health care solutions with limited or no effect, and they experience being met with mistrust and doubt by health care professionals, the social care system and by friends and relatives. Evidence-based treatment options are currently unavailable, however, a person-centered care model based...

  3. Single gene retrieval from thermally degraded DNA

    Indian Academy of Sciences (India)

    Lianwen Zhang; Lianwen Zhang

    2005-12-01

    To simulate single gene retrieval from ancient DNA, several related factors have been investigated. By monitoring a 889 bp polymerase chain reaction (PCR) product and genomic DNA degradation, we find that heat and oxygen (especially heat) are both crucial factors influencing DNA degradation. The heat influence, mainly represented by temperature and heating time, affects the DNA degradation via DNA depurination followed by cleavage of nearby phosphodiesters. The heating time influence is temperature-dependent. By reactive oxygen species (ROS) scavenging and 1,3-diphenyl-isobenzofuran (DPBF) bleaching experiments the influence of oxygen on DNA thermal degradation was shown to occur via a singlet oxygen pathway. A comparative study of the thermal degradation of cellular DNA and isolated DNA showed that cellular lipids can aggravate DNA thermal degradation. These results confirm the possibility of gene amplification from thermally degraded DNA. They can be used to evaluate the feasibility of the retrieval of single gene from ancient remains.

  4. Protease-degradable electrospun fibrous hydrogels

    Science.gov (United States)

    Wade, Ryan J.; Bassin, Ethan J.; Rodell, Christopher B.; Burdick, Jason A.

    2015-03-01

    Electrospun nanofibres are promising in biomedical applications to replicate features of the natural extracellular matrix (ECM). However, nearly all electrospun scaffolds are either non-degradable or degrade hydrolytically, whereas natural ECM degrades proteolytically, often through matrix metalloproteinases. Here we synthesize reactive macromers that contain protease-cleavable and fluorescent peptides and are able to form both isotropic hydrogels and electrospun fibrous hydrogels through a photoinitiated polymerization. These biomimetic scaffolds are susceptible to protease-mediated cleavage in vitro in a protease dose-dependent manner and in vivo in a subcutaneous mouse model using transdermal fluorescent imaging to monitor degradation. Importantly, materials containing an alternate and non-protease-cleavable peptide sequence are stable in both in vitro and in vivo settings. To illustrate the specificity in degradation, scaffolds with mixed fibre populations support selective fibre degradation based on individual fibre degradability. Overall, this represents a novel biomimetic approach to generate protease-sensitive fibrous scaffolds for biomedical applications.

  5. Airborne chemical contamination of a chemically amplified resist

    Science.gov (United States)

    MacDonald, Scott A.; Clecak, Nicholas J.; Wendt, H. R.; Willson, C. Grant; Snyder, Clinton D.; Knors, C. J.; Deyoe, N. B.; Maltabes, John G.; Morrow, James R.; McGuire, Anne E.; Holmes, Steven J.

    1991-06-01

    We have found that the performance of the t-BOC/onium salt resist system is severely degraded by vapor from organic bases. This effect is very pronounced and can be observed when the coated wafers stand for 15 minutes in air containing as little as 15 parts per billion (ppb) of an organic base. The observed effect, caused by this chemical contamination, depends on the tone of the resist system. For negative tone systems the UV exposure dose, required to obtain the correct linewidth, increases. While for the positive tone system, one observes the generation of a skin at the resist-air interface. Both effects are caused by the photogenerated acid being neutralized by the airborne organic base. There are a wide variety of commonly used materials which can liberate trace amounts of volatile amines and degrade resist performance. For example, fresh paint on a laboratory wall can exhibit this detrimental effect. These effects can be minimized by storing and processing the resist coated wafers in air that has passed through a specially designed, high efficiency carbon filter. The implementation of localized air filtration, to bathe the resist in chemically pure air, enabled this resist system to operate in a manufacturing environment at a rate of 100 wafers/hour.

  6. The chemistry of death--Adipocere degradation in modern graveyards.

    Science.gov (United States)

    Fiedler, S; Berns, A E; Schwark, L; Woelk, A T; Graw, M

    2015-12-01

    The formation of adipocere slows further decomposition and preserves corpses for decades or even centuries. This resistance to degradation is a serious problem, especially with regard to the reuse of graves after regular resting times. We present results from an exhumation series in modern graveyards where coffins from water-saturated earth graves contained adipocere embedded in black humic material after resting times of about 30 years. Based on the assumption that this humic material resulted from in situ degradation of adipocere, its presence contradicts the commonly held opinion that adipocere decomposition only occurs under aerobic conditions. To test our hypothesis, we collected black humic material, adipocere as well as soil samples above and below coffins from representative graves (n=7). A comprehensive chemical analysis of the samples substantiated our in situ degradation theory. Element compositions and fatty acid mass spectra confirmed that the humic black material originated from the corpses. A van Krevelen diagram classified the excavated adipocere material as lipid, whereas the black humic material was closer to the carbohydrate region. Mass fragmentograms of the humic material revealed the presence of large amounts of saturated vs. unsaturated nC16 and nC18 fatty acids, which is typical for adipocere. In addition, the soil samples exhibited a lipid signature deriving primarily from plant waxes and root components (C20C32). Solid-state (13)C NMR spectra of adipocere displayed well-resolved signals of saturated aliphatic chains and a signal that corresponded to carboxylic acid groups. The NMR spectra of the black humic material revealed signals characteristic of long aliphatic chains. The intensities varied in relation to the state of degradation of the sample, as did the signals of oxidized aliphatic chains, acetals and ketals, aromatic structures, esters and amids. The analyses confirmed that the black humic material was indeed derived from

  7. [Photocatalytic Degradation of Perfluorooctanoic Acid by Pd-TiO2 Photocatalyst].

    Science.gov (United States)

    Liu, Qing; Yu, Ze-bin; Zhang, Rui-han; Li, Ming-jie; Chen, Ying; Wang, Li; Kuang, Yu; Zhang, Bo; Zhu, You-hui

    2015-06-01

    Perfluorooctanoic acid (PFOA) is a new persistent organic pollutant which has got global concern for its wide distribution, high bioaccumulation and strong biological toxicity. In present study, the photocatalytic degradation of PFOA using palladium doped TiO2 (Pd-TiO2) prepared by chemical reduction method was investigated. The photocatalysts were characterized by XRD, FESEM and UV-vis DRS and were used for PFOA degradation under 365 nm UV irradiation. The results indicated that the grain size of TiO2 was smaller while the specific surface area increased and the absorption of ultraviolet light also enhanced after using chemical reduction method, but all these changes had no influence on PFOA degradation. However, the degradation was significantly enhanced because of the deposition of Pd, the fluoride concentration of PFOA was 6.62 mg x L(-1) after 7 h irradiation which was 7.3 times higher than that of TiO2 (P25). Experiments with the addition of trapping agent and nitrogen indicated that *OH played an important role in PFOA degradation while the presence of O2 accelerated the degradation. The main intermediate products of photocatalytic degradation of PFOA were authenticated by an ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry systems (UPLC-QTOF-MS). The probable photocatalytic degradation mechanism involves h+ attacking the carboxyl of PFOA and resulting in decarboxylation. The produced *CnF(2n +1) was oxidized by *OH underwent defluorinetion to form shorter-chain perfluorinated carboxylic acids. The significant enhancement of PFOA degradation can be ascribed to the palladium deposits, acting as electron traps on the Pd-TiO2 surface, which facilitated the transfer of photogenerated electrons and retarded the accumulation of electrons.

  8. Degradation of CL-20 by white-rot fungi.

    Science.gov (United States)

    Fournier, Diane; Monteil-Rivera, Fanny; Halasz, Annamaria; Bhatt, Manish; Hawari, Jalal

    2006-03-01

    In previous studies, we found that the emerging energetic chemical, CL-20 (C6H6N12O12, 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane), can be degraded following its initial denitration using both aerobic and anaerobic bacteria. The C and N mass balances were not determined due to the absence of labeled starting compounds. The present study describes the degradation of the emerging contaminant by Phanerochaete chrysosporium using ring-labeled [15N]-CL-20 and [14C]-CL-20. Ligninolytic cultures degraded CL-20 with the release of nitrous oxide (N2O) in amounts corresponding to 45% of the nitrogen content of CL-20. When ring-labeled [15N]-CL-20 was used, both 14N14NO and 15N14NO were observed, likely produced from -NO2 and N-NO2, respectively. The incubation of uniformly labeled [14C]-CL-20 with fungi led to the production of 14CO2 (> 80%). Another ligninolytic fungus, Irpex lacteus, was also able to degrade CL-20, but as for P. chrysosporium, no early intermediates were observed. When CL-20 was incubated with manganese peroxidase (MnP), we detected an intermediate with a [M-H]- mass ion at 345 Da (or 351 and 349 Da when using ring-labeled and nitro-labeled [15N]-CL-20, respectively) matching a molecular formula of C6H6N10O8. The intermediate was thus tentatively identified as a doubly denitrated CL-20 product. The concomitant release of nitrite ions (NO2-) with CL-20 degradation by MnP also supported the occurrence of an initial denitration prior to cleavage and decomposition. PMID:16112713

  9. Anaerobic degradation of benzene by marine sulfate-reducing bacteria

    Science.gov (United States)

    Musat, Florin; Wilkes, Heinz; Musat, Niculina; Kuypers, Marcel; Widdel, Friedrich

    2010-05-01

    Benzene, the archetypal aromatic hydrocarbon is a common constituent of crude oil and oil-refined products. As such, it can enter the biosphere through natural oil seeps or as a consequence of exploitation of fossil fuel reservoirs. Benzene is chemically very stable, due to the stabilizing aromatic electron system and to the lack of functional groups. Although the anaerobic degradation of benzene has been reported under denitrifying, sulfate-reducing and methanogenic conditions, the microorganisms involved and the initial biochemical steps of degradation remain insufficiently understood. Using marine sediment from a Mediterranean lagoon a sulfate-reducing enrichment culture with benzene as the sole organic substrate was obtained. Application of 16S rRNA gene-based methods showed that the enrichment was dominated (more than 85% of total cells) by a distinct phylotype affiliated with a clade of Deltaproteobacteria that include degraders of other aromatic hydrocarbons, such as naphthalene, ethylbenzene and m-xylene. Using benzoate as a soluble substrate in agar dilution series, several pure cultures closely related to Desulfotignum spp. and Desulfosarcina spp. were isolated. None of these strains was able to utilize benzene as a substrate and hybridizations with specific oligonucleotide probes showed that they accounted for as much as 6% of the total cells. Incubations with 13C-labeled benzene followed by Halogen in situ Hybridization - Secondary Ion Mass Spectroscopy (HISH-SIMS) analysis showed that cells of the dominant phylotype were highly enriched in 13C, while the accompanying bacteria had little or no 13C incorporation. These results demonstrate that the dominant phylotype was indeed the apparent benzene degrader. Dense-cell suspensions of the enrichment culture did not show metabolic activity toward added phenol or toluene, suggesting that benzene degradation did not proceed through anaerobic hydroxylation or methylation. Instead, benzoate was identified in

  10. Geochemistry Model Validation Report: Material Degradation and Release Model

    Energy Technology Data Exchange (ETDEWEB)

    H. Stockman

    2001-09-28

    The purpose of this Analysis and Modeling Report (AMR) is to validate the Material Degradation and Release (MDR) model that predicts degradation and release of radionuclides from a degrading waste package (WP) in the potential monitored geologic repository at Yucca Mountain. This AMR is prepared according to ''Technical Work Plan for: Waste Package Design Description for LA'' (Ref. 17). The intended use of the MDR model is to estimate the long-term geochemical behavior of waste packages (WPs) containing U. S . Department of Energy (DOE) Spent Nuclear Fuel (SNF) codisposed with High Level Waste (HLW) glass, commercial SNF, and Immobilized Plutonium Ceramic (Pu-ceramic) codisposed with HLW glass. The model is intended to predict (1) the extent to which criticality control material, such as gadolinium (Gd), will remain in the WP after corrosion of the initial WP, (2) the extent to which fissile Pu and uranium (U) will be carried out of the degraded WP by infiltrating water, and (3) the chemical composition and amounts of minerals and other solids left in the WP. The results of the model are intended for use in criticality calculations. The scope of the model validation report is to (1) describe the MDR model, and (2) compare the modeling results with experimental studies. A test case based on a degrading Pu-ceramic WP is provided to help explain the model. This model does not directly feed the assessment of system performance. The output from this model is used by several other models, such as the configuration generator, criticality, and criticality consequence models, prior to the evaluation of system performance. This document has been prepared according to AP-3.10Q, ''Analyses and Models'' (Ref. 2), and prepared in accordance with the technical work plan (Ref. 17).

  11. Geochemistry Model Validation Report: Material Degradation and Release Model

    International Nuclear Information System (INIS)

    The purpose of this Analysis and Modeling Report (AMR) is to validate the Material Degradation and Release (MDR) model that predicts degradation and release of radionuclides from a degrading waste package (WP) in the potential monitored geologic repository at Yucca Mountain. This AMR is prepared according to ''Technical Work Plan for: Waste Package Design Description for LA'' (Ref. 17). The intended use of the MDR model is to estimate the long-term geochemical behavior of waste packages (WPs) containing U. S . Department of Energy (DOE) Spent Nuclear Fuel (SNF) codisposed with High Level Waste (HLW) glass, commercial SNF, and Immobilized Plutonium Ceramic (Pu-ceramic) codisposed with HLW glass. The model is intended to predict (1) the extent to which criticality control material, such as gadolinium (Gd), will remain in the WP after corrosion of the initial WP, (2) the extent to which fissile Pu and uranium (U) will be carried out of the degraded WP by infiltrating water, and (3) the chemical composition and amounts of minerals and other solids left in the WP. The results of the model are intended for use in criticality calculations. The scope of the model validation report is to (1) describe the MDR model, and (2) compare the modeling results with experimental studies. A test case based on a degrading Pu-ceramic WP is provided to help explain the model. This model does not directly feed the assessment of system performance. The output from this model is used by several other models, such as the configuration generator, criticality, and criticality consequence models, prior to the evaluation of system performance. This document has been prepared according to AP-3.10Q, ''Analyses and Models'' (Ref. 2), and prepared in accordance with the technical work plan (Ref. 17)

  12. An evaluation of a pilot-scale nonthermal plasma advanced oxidation process for trace organic compound degradation.

    Science.gov (United States)

    Gerrity, Daniel; Stanford, Benjamin D; Trenholm, Rebecca A; Snyder, Shane A

    2010-01-01

    This study evaluated a pilot-scale nonthermal plasma (NTP) advanced oxidation process (AOP) for the degradation of trace organic compounds such as pharmaceuticals and potential endocrine disrupting compounds (EDCs). The degradation of seven indicator compounds was monitored in tertiary-treated wastewater and spiked surface water to evaluate the effects of differing water qualities on process efficiency. The tests were also conducted in batch and single-pass modes to examine contaminant degradation rates and the remediation capabilities of the technology, respectively. Values for electrical energy per order (EEO) of magnitude degradation ranged from meprobamate) in wastewater. Changes in the bulk organic matter based on UV(254) absorbance and excitation-emission matrices (EEM) were also monitored and correlated to contaminant degradation. These results indicate that NTP may be a viable alternative to more common AOPs due to its comparable energy requirements for contaminant degradation and its ability to operate without any additional feed chemicals. PMID:19822343

  13. Environmental Degradation: Causes and Consequences

    Directory of Open Access Journals (Sweden)

    Swati Tyagi

    2014-08-01

    Full Text Available The subject of environmental economics is at the forefront of the green debate: the environment can no longer be viewed as an entity separate from the economy. Environmental degradation is of many types and have many consequences. To address this challenge a number of studies have been conducted in both developing and developed countries applying different methods to capture health benefits from improved environmental quality. Minimizing exposure to environmental risk factors by enhancing air quality and access to improved sources of drinking and bathing water, sanitation and clean energy is found to be associated with significant health benefits and can contribute significantly to the achievement of the Millennium Development Goals of environmental sustainability, health and development. In this paper, I describe the national and global causes and consequences of environmental degradation and social injustice. This paper provides a review of the literature on studies associated with reduced environmental risk and in particular focusing on reduced air pollution, enhanced water quality and climate change mitigation.

  14. Degradation of Acenaphthene by Ozone

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Objective To investigate the oxidation of acenaphthene (Ace), a polycyclic aromatic hydrocarbon (PAH) with a saturated C-C bond by ozone and to characterize the intermediate products of ozonation. Methods Ozone was generated from filtered dry oxygen by an ozone generator and continually bubbled into a reactor containing 1g/L Ace dissolved in an acetonitrile/water solvent mixture (90/10, v/v) at a rate of 0.5 mg/s. HPLC was used to analyze the Ace concentration. Total organic carbon (TOC) was used to measure the amount of water soluble organic compounds. GC-MS was used to identify the ozonized products. Oxygen uptake rate (OUR) of activated sludge was used to characterize the biodegradability of ozonized products. Results During the ozonation process, Ace was degraded, new organic compounds were produced and these intermediate products were difficult mineralize by ozone, with increasing TOC of soluble organics. The ozonized products were degraded by activated sludge more easily than Ace. Conclusion Ozonation decomposes the Ace and improves its biodegradability. The ozonation combined with biological treatment is probably an efficient and economical way to mineralize acenaphthene in wastewater.

  15. Land degradation in the Canyoles river watershed, Eastern Spain

    Science.gov (United States)

    Cerdà, A.; Gonzalez Peñaloza, F. A.; Imeson, A. C.; Gimenez Morera, A.

    2012-04-01

    areas on soil erosion and degradation processes. Special attention is being paid to the citrus plantations expansion at the Canyoles river watershed as it was found the increase in soil erosion is due to the chemically managed citrus orchards (Cerdà et al., 2009). The economic changes on the citrus orchards are also analized. This research is being conducted by the EU project "Land and Ecosystem Degradation and Desertification: Assessing the Fit of Responses" LEDDRA 243857 CONSORTIUM AGREEMENT . TR07 - VII PROGRAMA MARCO - ENERGÍA FP7-ENERGY-2007-2-TREN. - European Union FP7. ENV.2009 243857. The experimental setup within the citrus plantation is being supported by the the research project CGL2008-02879/BTE

  16. Ametryne degradation by ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Debora Cristina de; Mori, Manoel Nunes; Duarte, Celina Lopes [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)]. E-mails: deboracandrade@globo.com; mnmori@ipen.br; clduarte@ipen.br; Melo, Rita Paiva [Technological and Nuclear Institute (ITN), Sacavem (Portugal)]. E-mail: ritamelo@itn.pt

    2007-07-01

    Ametryne may be released to the environment during its manufacture, transport, storage, formulation and use as selective herbicide for the control of annual broadleaf and grass weeds. It is applied as an aqueous suspension for preemergence or post-directed applications on crops. Depending on the pesticide formulation and type of application, ametryne residues may be detectable in water, soil and on the surfaces for months or years. The herbicide used to this study was Ametryne (commercial name, Gesapax 500), commonly used on field crops and on corn and commercialized since 1975. Ametryne was analyzed by gas chromatography (GC Shimadzu 17A), after extraction with hexane/dichloromethane (1:1 v/v) solution. The calibration curve was obtained with a regression coefficient of 0.9871. In addition, the relative standard deviation was lower than 10%. The radiation-processing yield was evaluated by the destruction G-value (Gd) (Eq. 1), that is defined by the number of destroyed molecules by absorption of 100 eV of energy from ionizing radiation. Different concentrations of the herbicide (11.4 mol L{sup -1}; 22.7 mol L{sup -1}; 34.1 mol L{sup -1} and 45.5 mol L{sup -1}) were irradiated at the AECL 'Gammacell 220' {sup 60}Co source, with 1 kGy, 3 kGy, 6 kGy, 9 kGy, 12 kGy, 15 kGy and 30 kGy absorbed doses. After irradiation processing, the ametryne highest reduction rate occurs at low doses of radiation: at 6 kGy more than 85-90% of all ametryne compounds were removed. Two products of incomplete degradation of ametryne were identified as s-triazyne isomers. However, further work is needed in order to fully understand the ametryne degradation mechanisms the degradation yield of ametryne depends on its initial concentration and the process seems to be more efficient at higher concentrations. (author)

  17. Chemical information science coverage in Chemical Abstracts.

    Science.gov (United States)

    Wiggins, G

    1987-02-01

    For many years Chemical Abstracts has included in its coverage publications on chemical documentation or chemical information science. Although the bulk of those publications can be found in section 20 of Chemical Abstracts, many relevant articles were found scattered among 39 other sections of CA in 1984-1985. In addition to the scattering of references in CA, the comprehensiveness of Chemical Abstracts as a secondary source for chemical information science is called into question. Data are provided on the journals that contributed the most references on chemical information science and on the languages of publication of relevant articles.

  18. Cellulose degradation by oxidative enzymes

    Directory of Open Access Journals (Sweden)

    Maria Dimarogona

    2012-09-01

    Full Text Available Enzymatic degradation of plant biomass has attracted intensive research interest for the production of economically viable biofuels. Here we present an overview of the recent findings on biocatalysts implicated in the oxidative cleavage of cellulose, including polysaccharide monooxygenases (PMOs or LPMOs which stands for lytic PMOs, cellobiose dehydrogenases (CDHs and members of carbohydrate-binding module family 33 (CBM33. PMOs, a novel class of enzymes previously termed GH61s, boost the efficiency of common cellulases resulting in increased hydrolysis yields while lowering the protein loading needed. They act on the crystalline part of cellulose by generating oxidized and non-oxidized chain ends. An external electron donor is required for boosting the activity of PMOs. We discuss recent findings concerning their mechanism of action and identify issues and questions to be addressed in the future.

  19. The Degraded Poisson Wiretap Channel

    CERN Document Server

    Laourine, Amine

    2010-01-01

    Providing security guarantees for wireless communication is critically important for today's applications. While previous work in this area has concentrated on radio frequency (RF) channels, providing security guarantees for RF channels is inherently difficult because they are prone to rapid variations due small scale fading. Wireless optical communication, on the other hand, is inherently more secure than RF communication due to the intrinsic aspects of the signal propagation in the optical and near-optical frequency range. In this paper, secure communication over wireless optical links is examined by studying the secrecy capacity of a direct detection system. For the degraded Poisson wiretap channel, a closed-form expression of the secrecy capacity is given. A complete characterization of the general rate-equivocation region is also presented. For achievability, an optimal code is explicitly constructed by using the structured code designed by Wyner for the Poisson channel. The converse is proved in two dif...

  20. Bacterial Degradation of Aromatic Compounds

    Directory of Open Access Journals (Sweden)

    Qing X. Li

    2009-01-01

    Full Text Available Aromatic compounds are among the most prevalent and persistent pollutants in the environment. Petroleum-contaminated soil and sediment commonly contain a mixture of polycyclic aromatic hydrocarbons (PAHs and heterocyclic aromatics. Aromatics derived from industrial activities often have functional groups such as alkyls, halogens and nitro groups. Biodegradation is a major mechanism of removal of organic pollutants from a contaminated site. This review focuses on bacterial degradation pathways of selected aromatic compounds. Catabolic pathways of naphthalene, fluorene, phenanthrene, fluoranthene, pyrene, and benzo[a]pyrene are described in detail. Bacterial catabolism of the heterocycles dibenzofuran, carbazole, dibenzothiophene, and dibenzodioxin is discussed. Bacterial catabolism of alkylated PAHs is summarized, followed by a brief discussion of proteomics and metabolomics as powerful tools for elucidation of biodegradation mechanisms.