Science.gov

Sample records for chemical absorption-biological reduction

  1. A Biophysicochemical Model for NO Removal by the Chemical Absorption-Biological Reduction Integrated Process.

    PubMed

    Zhao, Jingkai; Xia, Yinfeng; Li, Meifang; Li, Sujing; Li, Wei; Zhang, Shihan

    2016-08-16

    The chemical absorption-biological reduction (CABR) integrated process is regarded as a promising technology for NOx removal from flue gas. To advance the scale-up of the CABR process, a mathematic model based on mass transfer with reaction in the gas, liquid, and biofilm was developed to simulate and predict the NOx removal by the CABR system in a biotrickling filter. The developed model was validated by the experimental results and subsequently was used to predict the system performance under different operating conditions, such as NO and O2 concentration and gas and liquid flow rate. NO distribution in the gas phase along the biotrickling filter was also modeled and predicted. On the basis of the modeling results, the liquid flow rate and total iron concentration were optimized to achieve >90% NO removal efficiency. Furthermore, sensitivity analysis of the model revealed that the performance of the CABR process was controlled by the bioreduction activity of Fe(III)EDTA. This work will provide the guideline for the design and operation of the CABR process in the industrial application. PMID:27442232

  2. Evaluation of microbial reduction of Fe(III)EDTA in a chemical absorption-biological reduction integrated NOx removal system

    SciTech Connect

    Wei Li; Cheng-Zhi Wu; Shi-Han Zhang; Ke Shao; Yao Shi

    2007-01-15

    A chemical absorption-biological reduction integrated process can be used to remove nitrogen oxides (NOx) from flue gas. In such a process, nitric oxide (NO) can be effectively absorbed by the ferrous chelate of ethylenediaminetetraacetate (Fe(II)EDTA) to form Fe(II)EDTA-NO, which can be biologically regenerated by denitrifying bacteria. However, in the course of these processes, part of the Fe(II)EDTA is also oxidized to Fe(III)EDTA. The reduction of Fe(III)EDTA to Fe(II)EDTA depends on the activity of iron-reducing bacteria in the system. Therefore, the effectiveness of the system relies on how to effectively bioreduce Fe(III)EDTA and Fe(II)EDTA-NO in the system. In this paper, a strain identified as Escherichia coli FR-2 (iron-reducing bacterium) was used to investigate the reduction rate of Fe(III)EDTA. The experimental results indicate that Fe(II)EDTA-NO and Fe(II)EDTA in the system can inhibit both the FR-2 cell growth and thus affect the Fe(III)EDTA reduction. The FR-2 cell growth rate and Fe(III)EDTA reduction rate decreased with increasing Fe(II)EDTA-NO and Fe(II)EDTA concentration in the solution. When the concentration of Fe(II)EDTA-NO reached 3.7 mM, the FR-2 cell growth almost stopped. A mathematical model was developed to explain the cell growth and inhibition kinetics. The predicted results are close to the experimental data and provide a preliminary evaluation of the kinetics of the biologically mediated reactions necessary to regenerate the spent scrubber solution. 33 refs., 7 figs., 2 tabs.

  3. NOx removal from simulated flue gas by chemical absorption-biological reduction integrated approach in a biofilter

    SciTech Connect

    Shi-Han Zhang; Ling-Lin Cai; Xu-Hong Mi; Jin-Lin Jiang; Wei Li

    2008-05-15

    A chemical absorption-biological reduction integrated approach, which combines the advantages of both the chemical and biological technologies, is employed to achieve the removal of nitrogen monoxide (NO) from the simulated flue gas. The biological reduction of NO to nitrogen gas (N{sub 2}) and regeneration of the absorbent Fe(II)EDTA (EDTA:ethylenediaminetetraacetate) take place under thermophilic conditions (50 {+-} 0.5{sup o}C). The performance of a laboratory-scale biofilter was investigated for treating NOx gas in this study. Shock loading studies were performed to ascertain the response of the biofilter to fluctuations of inlet loading rates (0.48-28.68 g NO m{sup 3} h{sup -1}). A maximum elimination capacity (18.78 g NO m{sup 3} h{sup -1}) was achieved at a loading rate of 28.68 g NO m{sup 3} h{sup -1} and maintained 5 h operation at the steady state. Additionally, the effect of certain gaseous compounds (e.g., O{sub 2} and SO{sub 2}) on the NO removal was also investigated. A mathematical model was developed to describe the system performance. The model has been able to predict experimental results for different inlet NO concentrations. In summary, both theoretical prediction and experimental investigation confirm that biofilter can achieve high removal rate for NO in high inlet concentrations under both steady and transient states. 21 refs., 9 figs.

  4. Pathway of FeEDTA transformation and its impact on performance of NOx removal in a chemical absorption-biological reduction integrated process.

    PubMed

    Li, Wei; Zhao, Jingkai; Zhang, Lei; Xia, Yinfeng; Liu, Nan; Li, Sujing; Zhang, Shihan

    2016-01-01

    A novel chemical absorption-biological reduction (CABR) integrated process, employing ferrous ethylenediaminetetraacetate (Fe(II)EDTA) as a solvent, is deemed as a potential option for NOx removal from the flue gas. Previous work showed that the Fe(II)EDTA concentration was critical for the NOx removal in the CABR process. In this work, the pathway of FeEDTA (Fe(III)/Fe(II)-EDTA) transformation was investigated to assess its impact on the NOx removal in a biofilter. Experimental results revealed that the FeEDTA transformation involved iron precipitation and EDTA degradation. X-ray photoelectron spectroscopy analysis confirmed the iron was precipitated in the form of Fe(OH)3. The iron mass balance analysis showed 44.2% of the added iron was precipitated. The EDTA degradation facilitated the iron precipitation. Besides chemical oxidation, EDTA biodegradation occurred in the biofilter. The addition of extra EDTA helped recover the iron from the precipitation. The transformation of FeEDTA did not retard the NO removal. In addition, EDTA rather than the iron concentration determined the NO removal efficiency.

  5. Pathway of FeEDTA transformation and its impact on performance of NOx removal in a chemical absorption-biological reduction integrated process

    PubMed Central

    Li, Wei; Zhao, Jingkai; Zhang, Lei; Xia, Yinfeng; Liu, Nan; Li, Sujing; Zhang, Shihan

    2016-01-01

    A novel chemical absorption-biological reduction (CABR) integrated process, employing ferrous ethylenediaminetetraacetate (Fe(II)EDTA) as a solvent, is deemed as a potential option for NOx removal from the flue gas. Previous work showed that the Fe(II)EDTA concentration was critical for the NOx removal in the CABR process. In this work, the pathway of FeEDTA (Fe(III)/Fe(II)-EDTA) transformation was investigated to assess its impact on the NOx removal in a biofilter. Experimental results revealed that the FeEDTA transformation involved iron precipitation and EDTA degradation. X-ray photoelectron spectroscopy analysis confirmed the iron was precipitated in the form of Fe(OH)3. The iron mass balance analysis showed 44.2% of the added iron was precipitated. The EDTA degradation facilitated the iron precipitation. Besides chemical oxidation, EDTA biodegradation occurred in the biofilter. The addition of extra EDTA helped recover the iron from the precipitation. The transformation of FeEDTA did not retard the NO removal. In addition, EDTA rather than the iron concentration determined the NO removal efficiency. PMID:26743930

  6. Reduction of chemical reaction models

    NASA Technical Reports Server (NTRS)

    Frenklach, Michael

    1991-01-01

    An attempt is made to reconcile the different terminologies pertaining to reduction of chemical reaction models. The approaches considered include global modeling, response modeling, detailed reduction, chemical lumping, and statistical lumping. The advantages and drawbacks of each of these methods are pointed out.

  7. Current advances of integrated processes combining chemical absorption and biological reduction for NO x removal from flue gas.

    PubMed

    Zhang, Shihan; Chen, Han; Xia, Yinfeng; Liu, Nan; Lu, Bi-Hong; Li, Wei

    2014-10-01

    Anthropogenic nitrogen oxides (NO x ) emitted from the fossil-fuel-fired power plants cause adverse environmental issues such as acid rain, urban ozone smoke, and photochemical smog. A novel chemical absorption-biological reduction (CABR) integrated process under development is regarded as a promising alternative to the conventional selective catalytic reduction processes for NO x removal from the flue gas because it is economic and environmentally friendly. CABR process employs ferrous ethylenediaminetetraacetate [Fe(II)EDTA] as a solvent to absorb the NO x following microbial denitrification of NO x to harmless nitrogen gas. Meanwhile, the absorbent Fe(II)EDTA is biologically regenerated to sustain the adequate NO x removal. Compared with conventional denitrification process, CABR not only enhances the mass transfer of NO from gas to liquid phase but also minimize the impact of oxygen on the microorganisms. This review provides the current advances of the development of the CABR process for NO x removal from the flue gas.

  8. CoPt nanoparticles by chemical reduction

    NASA Astrophysics Data System (ADS)

    Wang, H. L.; Zhang, Y.; Huang, Y.; Zeng, Q.; Hadjipanayis, George C.

    2004-05-01

    CoPt nanoparticles with a size of 1-2nm were synthesized by chemical reduction using the solvents of water and alcohol. A phase transformation from the originally disordered face centered cubic (FCC) structure to an ordered face centered tetragonal L10 structure occurred after annealing, which results in the coercivity up to 9kOe because of the high anisotropy of the tetragonal phase (K~2-4×107erg/cm3) (Philos. Mag. 13 (1966) 567; IEEE Trans. Magn. 20 (1984) 1625). HREM images of as-grow Co48Pt52 shows the single-crystalline FCC structure with the shape of columnar and spherical.

  9. Current advances of integrated processes combining chemical absorption and biological reduction for NO x removal from flue gas.

    PubMed

    Zhang, Shihan; Chen, Han; Xia, Yinfeng; Liu, Nan; Lu, Bi-Hong; Li, Wei

    2014-10-01

    Anthropogenic nitrogen oxides (NO x ) emitted from the fossil-fuel-fired power plants cause adverse environmental issues such as acid rain, urban ozone smoke, and photochemical smog. A novel chemical absorption-biological reduction (CABR) integrated process under development is regarded as a promising alternative to the conventional selective catalytic reduction processes for NO x removal from the flue gas because it is economic and environmentally friendly. CABR process employs ferrous ethylenediaminetetraacetate [Fe(II)EDTA] as a solvent to absorb the NO x following microbial denitrification of NO x to harmless nitrogen gas. Meanwhile, the absorbent Fe(II)EDTA is biologically regenerated to sustain the adequate NO x removal. Compared with conventional denitrification process, CABR not only enhances the mass transfer of NO from gas to liquid phase but also minimize the impact of oxygen on the microorganisms. This review provides the current advances of the development of the CABR process for NO x removal from the flue gas. PMID:25149446

  10. Source reduction from chemical plants using on-line optimization

    SciTech Connect

    Zhang, Z.; Pike, R.W.; Hertwig, T.A.

    1995-12-01

    An effective approach for source reduction in chemical plants has been demonstrated using on-line optimization with flowsheeting (ASPEN PLUS) for process optimization and parameter estimation and the Tjao-Biegler algorithm implemented in a mathematical programming language (GAMS/MINOS) for data reconciliation and gross error detection. Results for a Monsanto sulfuric acid plant with a Bailey distributed control system showed a 25% reduction in the sulfur dioxide emissions and a 17% improvement in the profit over the current operating conditions. Details of the methods used are described.

  11. The subtle business of model reduction for stochastic chemical kinetics.

    PubMed

    Gillespie, Dan T; Cao, Yang; Sanft, Kevin R; Petzold, Linda R

    2009-02-14

    This paper addresses the problem of simplifying chemical reaction networks by adroitly reducing the number of reaction channels and chemical species. The analysis adopts a discrete-stochastic point of view and focuses on the model reaction set S(1)<=>S(2)-->S(3), whose simplicity allows all the mathematics to be done exactly. The advantages and disadvantages of replacing this reaction set with a single S(3)-producing reaction are analyzed quantitatively using novel criteria for measuring simulation accuracy and simulation efficiency. It is shown that in all cases in which such a model reduction can be accomplished accurately and with a significant gain in simulation efficiency, a procedure called the slow-scale stochastic simulation algorithm provides a robust and theoretically transparent way of implementing the reduction.

  12. Ultralow Concentration Mercury Treatment Using Chemical Reduction and Air Stripping

    SciTech Connect

    Looney, B.B.

    2001-05-21

    Field, laboratory and engineering data confirmed the efficacy of chemical reduction and air stripping as an ultralow concentration mercury treatment concept for water containing Hg(II). The simple process consists of dosing the water with low levels of stannous chloride (Sn(II)) to cover the mercury to Hg degrees. This mercury species can easily be removed from the water by air stripping or sparging.

  13. Reduction of chemical reaction networks through delay distributions.

    PubMed

    Barrio, Manuel; Leier, André; Marquez-Lago, Tatiana T

    2013-03-14

    Accurate modelling and simulation of dynamic cellular events require two main ingredients: an adequate description of key chemical reactions and simulation of such chemical events in reasonable time spans. Quite logically, posing the right model is a crucial step for any endeavour in Computational Biology. However, more often than not, it is the associated computational costs which actually limit our capabilities of representing complex cellular behaviour. In this paper, we propose a methodology aimed at representing chains of chemical reactions by much simpler, reduced models. The abridgement is achieved by generation of model-specific delay distribution functions, consecutively fed to a delay stochastic simulation algorithm. We show how such delay distributions can be analytically described whenever the system is solely composed of consecutive first-order reactions, with or without additional "backward" bypass reactions, yielding an exact reduction. For models including other types of monomolecular reactions (constitutive synthesis, degradation, or "forward" bypass reactions), we discuss why one must adopt a numerical approach for its accurate stochastic representation, and propose two alternatives for this. In these cases, the accuracy depends on the respective numerical sample size. Our model reduction methodology yields significantly lower computational costs while retaining accuracy. Quite naturally, computational costs increase alongside network size and separation of time scales. Thus, we expect our model reduction methodologies to significantly decrease computational costs in these instances. We anticipate the use of delays in model reduction will greatly alleviate some of the current restrictions in simulating large sets of chemical reactions, largely applicable in pharmaceutical and biological research.

  14. Reduction of chemical reaction networks through delay distributions

    NASA Astrophysics Data System (ADS)

    Barrio, Manuel; Leier, André; Marquez-Lago, Tatiana T.

    2013-03-01

    Accurate modelling and simulation of dynamic cellular events require two main ingredients: an adequate description of key chemical reactions and simulation of such chemical events in reasonable time spans. Quite logically, posing the right model is a crucial step for any endeavour in Computational Biology. However, more often than not, it is the associated computational costs which actually limit our capabilities of representing complex cellular behaviour. In this paper, we propose a methodology aimed at representing chains of chemical reactions by much simpler, reduced models. The abridgement is achieved by generation of model-specific delay distribution functions, consecutively fed to a delay stochastic simulation algorithm. We show how such delay distributions can be analytically described whenever the system is solely composed of consecutive first-order reactions, with or without additional "backward" bypass reactions, yielding an exact reduction. For models including other types of monomolecular reactions (constitutive synthesis, degradation, or "forward" bypass reactions), we discuss why one must adopt a numerical approach for its accurate stochastic representation, and propose two alternatives for this. In these cases, the accuracy depends on the respective numerical sample size. Our model reduction methodology yields significantly lower computational costs while retaining accuracy. Quite naturally, computational costs increase alongside network size and separation of time scales. Thus, we expect our model reduction methodologies to significantly decrease computational costs in these instances. We anticipate the use of delays in model reduction will greatly alleviate some of the current restrictions in simulating large sets of chemical reactions, largely applicable in pharmaceutical and biological research.

  15. Fermentation, fractionation and purification of streptokinase by chemical reduction method

    PubMed Central

    Karimi, Z; Babashamsi, M; Asgarani, E; Niakan, M; Salimi, A

    2011-01-01

    Background and Objectives Streptokinase is used clinically as an intravenous thrombolytic agent for the treatment of acute myocardial infarction and is commonly prepared from cultures of Streptococcus equisimilis strain H46A. The objective of the present study was the production of streptokinase from strain H46A and purification by chemical reduction method. Materials and Methods The rate of streptokinase production evaluated under the effect of changes on some fermentation factors. Moreover, due to the specific structure of streptokinase, a chemical reduction method employed for the purification of streptokinase from the fermentation broth. The H46A strain of group C streptococcus, was grown in a fermentor. The proper pH adjusted with NaOH under glucose feeding in an optimum temperature. The supernatant of the fermentation product was sterilized by filtration and concentrated by ultrafiltration. The pH of the concentrate was adjusted, cooled, and precipitated by methanol. Protein solution was reduced with dithiothreitol (DTT). Impurities settled down by aldrithiol-2 and the biological activity of supernatant containing streptokinase was determined. Results In the fed –batch culture, the rate of streptokinase production increased over two times as compared with the batch culture and the impurities were effectively separated from streptokinase by reduction method. Conclusion Improvements in SK production are due to a decrease in lag phase period and increase in the growth rate of logarithmic phase. The methods of purification often result in unacceptable losses of streptokinase, but the chemical reduction method give high yield of streptokinase and is easy to perform it. PMID:22347582

  16. Chemical labeling of carbohydrates by oxidation and sodium borohydride reduction.

    PubMed

    Fukuda, M

    2001-05-01

    This unit describes a collection of methods for chemical labeling of carbohydrates (free oligosaccharides or oligosaccharides conjugated to proteins, peptides, or lipids) by oxidation followed by reduction or by direct reduction. Oligosaccharides can be labeled with either radioisotopes or nonradioactive fluorescent molecules. These labelings allow one to follow the oligosaccharides during chromatography and in cells if labeled by fluorescent molecules. Selective oxidation with mild periodate followed by reduction with tritiated sodium borohydride results in selective radiolabeling of sialic acid residues on oligosaccharides or glycoproteins. Alternatively, treatment of samples with galactose oxidase results in oxidation of galactose or N-acetylgalactosamine residues at nonreducing termini, rendering these residues susceptible to labeling with NaB[3H]4. Oxidized glycoconjugates can also be labeled using the fluorescent probe lucifer yellow CH. Free oligosaccharides can be labeled by reduction with NaB[3H]4. An additional protocol describes the release and simultaneous labeling of O-glycan oligosaccharides by alkaline beta-elimination in the presence of NaB[3H]4.

  17. The enzymatic and chemical reduction of extended biliverdins.

    PubMed

    Frydman, R B; Bari, S; Tomaro, M L; Frydman, B

    1990-08-31

    The substrate specificity of rat liver biliverdin reductase was probed using helical and extended biliverdins. The former were the ZZZ-all-syn biliverdins IX alpha and IX gamma, and the latter were the 5Z-syn, 10Z-syn, 15Z-anti; 5Z-anti, 10E-anti, 15E-anti biliverdins. It was found that the reduction rates of the biliverdins increased with the progressive stretching of their conformations. The most extended biliverdin was reduced at a higher rate than biliverdin IX alpha. The chemical reduction rates to bilirubins followed a similar pattern. Nucleophilic addition of 2-mercaptoethanol to the C10 methine was also favored in the extended biliverdins. PMID:2393401

  18. A chemical reduction approach to the synthesis of copper nanoparticles

    NASA Astrophysics Data System (ADS)

    Khan, Ayesha; Rashid, Audil; Younas, Rafia; Chong, Ren

    2016-11-01

    Development of improved methods for the synthesis of copper nanoparticles is of high priority for the advancement of material science and technology. Herein, starch-protected zero-valent copper (Cu) nanoparticles have been successfully synthesized by a novel facile route. The method is based on the chemical reduction in aqueous copper salt using ascorbic acid as reducing agent at low temperature (80 °C). X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy measurements were taken to investigate the size, structure and composition of synthesized Cu nanocrystals, respectively. Average crystallite size of Cu nanocrystals calculated from the major diffraction peaks using the Scherrer formula is about 28.73 nm. It is expected that the outcomes of the study take us a step closer toward designing rational strategies for the synthesis of nascent Cu nanoparticles without inert gas protection.

  19. Chemical oxygen demand reduction in coffee wastewater through chemical flocculation and advanced oxidation processes.

    PubMed

    Zayas Pérez, Teresa; Geissler, Gunther; Hernandez, Fernando

    2007-01-01

    The removal of the natural organic matter present in coffee processing wastewater through chemical coagulation-flocculation and advanced oxidation processes (AOP) had been studied. The effectiveness of the removal of natural organic matter using commercial flocculants and UV/H2O2, UV/O3 and UV/H2O2/O3 processes was determined under acidic conditions. For each of these processes, different operational conditions were explored to optimize the treatment efficiency of the coffee wastewater. Coffee wastewater is characterized by a high chemical oxygen demand (COD) and low total suspended solids. The outcomes of coffee wastewater treatment using coagulation-flocculation and photodegradation processes were assessed in terms of reduction of COD, color, and turbidity. It was found that a reduction in COD of 67% could be realized when the coffee wastewater was treated by chemical coagulation-flocculation with lime and coagulant T-1. When coffee wastewater was treated by coagulation-flocculation in combination with UV/H2O2, a COD reduction of 86% was achieved, although only after prolonged UV irradiation. Of the three advanced oxidation processes considered, UV/H2O2, UV/O3 and UV/H2O2/O3, we found that the treatment with UV/H2O2/O3 was the most effective, with an efficiency of color, turbidity and further COD removal of 87%, when applied to the flocculated coffee wastewater.

  20. Order Reduction of the Chemical Master Equation via Balanced Realisation

    PubMed Central

    López-Caamal, Fernando; Marquez-Lago, Tatiana T.

    2014-01-01

    We consider a Markov process in continuous time with a finite number of discrete states. The time-dependent probabilities of being in any state of the Markov chain are governed by a set of ordinary differential equations, whose dimension might be large even for trivial systems. Here, we derive a reduced ODE set that accurately approximates the probabilities of subspaces of interest with a known error bound. Our methodology is based on model reduction by balanced truncation and can be considerably more computationally efficient than solving the chemical master equation directly. We show the applicability of our method by analysing stochastic chemical reactions. First, we obtain a reduced order model for the infinitesimal generator of a Markov chain that models a reversible, monomolecular reaction. Later, we obtain a reduced order model for a catalytic conversion of substrate to a product (a so-called Michaelis-Menten mechanism), and compare its dynamics with a rapid equilibrium approximation method. For this example, we highlight the savings on the computational load obtained by means of the reduced-order model. Furthermore, we revisit the substrate catalytic conversion by obtaining a lower-order model that approximates the probability of having predefined ranges of product molecules. In such an example, we obtain an approximation of the output of a model with 5151 states by a reduced model with 16 states. Finally, we obtain a reduced-order model of the Brusselator. PMID:25121581

  1. Order reduction of the chemical master equation via balanced realisation.

    PubMed

    López-Caamal, Fernando; Marquez-Lago, Tatiana T

    2014-01-01

    We consider a Markov process in continuous time with a finite number of discrete states. The time-dependent probabilities of being in any state of the Markov chain are governed by a set of ordinary differential equations, whose dimension might be large even for trivial systems. Here, we derive a reduced ODE set that accurately approximates the probabilities of subspaces of interest with a known error bound. Our methodology is based on model reduction by balanced truncation and can be considerably more computationally efficient than solving the chemical master equation directly. We show the applicability of our method by analysing stochastic chemical reactions. First, we obtain a reduced order model for the infinitesimal generator of a Markov chain that models a reversible, monomolecular reaction. Later, we obtain a reduced order model for a catalytic conversion of substrate to a product (a so-called Michaelis-Menten mechanism), and compare its dynamics with a rapid equilibrium approximation method. For this example, we highlight the savings on the computational load obtained by means of the reduced-order model. Furthermore, we revisit the substrate catalytic conversion by obtaining a lower-order model that approximates the probability of having predefined ranges of product molecules. In such an example, we obtain an approximation of the output of a model with 5151 states by a reduced model with 16 states. Finally, we obtain a reduced-order model of the Brusselator. PMID:25121581

  2. Order reduction of the chemical master equation via balanced realisation.

    PubMed

    López-Caamal, Fernando; Marquez-Lago, Tatiana T

    2014-01-01

    We consider a Markov process in continuous time with a finite number of discrete states. The time-dependent probabilities of being in any state of the Markov chain are governed by a set of ordinary differential equations, whose dimension might be large even for trivial systems. Here, we derive a reduced ODE set that accurately approximates the probabilities of subspaces of interest with a known error bound. Our methodology is based on model reduction by balanced truncation and can be considerably more computationally efficient than solving the chemical master equation directly. We show the applicability of our method by analysing stochastic chemical reactions. First, we obtain a reduced order model for the infinitesimal generator of a Markov chain that models a reversible, monomolecular reaction. Later, we obtain a reduced order model for a catalytic conversion of substrate to a product (a so-called Michaelis-Menten mechanism), and compare its dynamics with a rapid equilibrium approximation method. For this example, we highlight the savings on the computational load obtained by means of the reduced-order model. Furthermore, we revisit the substrate catalytic conversion by obtaining a lower-order model that approximates the probability of having predefined ranges of product molecules. In such an example, we obtain an approximation of the output of a model with 5151 states by a reduced model with 16 states. Finally, we obtain a reduced-order model of the Brusselator.

  3. The Use of Chemical Probes for the Characterization of the Predominant Abiotic Reductants in Anaerobic Sediments

    EPA Science Inventory

    Identifying the predominant chemical reductants and pathways for electron transfer in anaerobic systems is paramount to the development of environmental fate models that incorporate pathways for abiotic reductive transformations. Currently, such models do not exist. In this chapt...

  4. Less is Better. Laboratory Chemical Management for Waste Reduction.

    ERIC Educational Resources Information Center

    American Chemical Society, Washington, DC.

    An objective of the American Chemical Society is to promote alternatives to landfilling for the disposal of laboratory chemical wastes. One method is to reduce the amount of chemicals that become wastes. This is the basis for the "less is better" philosophy. This bulletin discusses various techniques involved in purchasing control, inventory…

  5. Model reduction for stochastic chemical systems with abundant species.

    PubMed

    Smith, Stephen; Cianci, Claudia; Grima, Ramon

    2015-12-01

    Biochemical processes typically involve many chemical species, some in abundance and some in low molecule numbers. We first identify the rate constant limits under which the concentrations of a given set of species will tend to infinity (the abundant species) while the concentrations of all other species remains constant (the non-abundant species). Subsequently, we prove that, in this limit, the fluctuations in the molecule numbers of non-abundant species are accurately described by a hybrid stochastic description consisting of a chemical master equation coupled to deterministic rate equations. This is a reduced description when compared to the conventional chemical master equation which describes the fluctuations in both abundant and non-abundant species. We show that the reduced master equation can be solved exactly for a number of biochemical networks involving gene expression and enzyme catalysis, whose conventional chemical master equation description is analytically impenetrable. We use the linear noise approximation to obtain approximate expressions for the difference between the variance of fluctuations in the non-abundant species as predicted by the hybrid approach and by the conventional chemical master equation. Furthermore, we show that surprisingly, irrespective of any separation in the mean molecule numbers of various species, the conventional and hybrid master equations exactly agree for a class of chemical systems.

  6. Model reduction for stochastic chemical systems with abundant species

    SciTech Connect

    Smith, Stephen; Cianci, Claudia; Grima, Ramon

    2015-12-07

    Biochemical processes typically involve many chemical species, some in abundance and some in low molecule numbers. We first identify the rate constant limits under which the concentrations of a given set of species will tend to infinity (the abundant species) while the concentrations of all other species remains constant (the non-abundant species). Subsequently, we prove that, in this limit, the fluctuations in the molecule numbers of non-abundant species are accurately described by a hybrid stochastic description consisting of a chemical master equation coupled to deterministic rate equations. This is a reduced description when compared to the conventional chemical master equation which describes the fluctuations in both abundant and non-abundant species. We show that the reduced master equation can be solved exactly for a number of biochemical networks involving gene expression and enzyme catalysis, whose conventional chemical master equation description is analytically impenetrable. We use the linear noise approximation to obtain approximate expressions for the difference between the variance of fluctuations in the non-abundant species as predicted by the hybrid approach and by the conventional chemical master equation. Furthermore, we show that surprisingly, irrespective of any separation in the mean molecule numbers of various species, the conventional and hybrid master equations exactly agree for a class of chemical systems.

  7. Model reduction for stochastic chemical systems with abundant species

    NASA Astrophysics Data System (ADS)

    Smith, Stephen; Cianci, Claudia; Grima, Ramon

    2015-12-01

    Biochemical processes typically involve many chemical species, some in abundance and some in low molecule numbers. We first identify the rate constant limits under which the concentrations of a given set of species will tend to infinity (the abundant species) while the concentrations of all other species remains constant (the non-abundant species). Subsequently, we prove that, in this limit, the fluctuations in the molecule numbers of non-abundant species are accurately described by a hybrid stochastic description consisting of a chemical master equation coupled to deterministic rate equations. This is a reduced description when compared to the conventional chemical master equation which describes the fluctuations in both abundant and non-abundant species. We show that the reduced master equation can be solved exactly for a number of biochemical networks involving gene expression and enzyme catalysis, whose conventional chemical master equation description is analytically impenetrable. We use the linear noise approximation to obtain approximate expressions for the difference between the variance of fluctuations in the non-abundant species as predicted by the hybrid approach and by the conventional chemical master equation. Furthermore, we show that surprisingly, irrespective of any separation in the mean molecule numbers of various species, the conventional and hybrid master equations exactly agree for a class of chemical systems.

  8. IN-SITU CHEMICAL OXIDATION - DNAPL MASS REDUCTION TECHNOLOGY

    EPA Science Inventory

    In-situ chemical oxidation (ISCO) is a rapidly developing technology used at hazardous waste sites where oxidants and complimentary reagents are injected into the subsurface to transform organic contaminants into less toxic byproducts. This technology is being used at new sites ...

  9. A POLLUTION REDUCTION METHODOLOGY FOR CHEMICAL PROCESS SIMULATORS

    EPA Science Inventory

    A pollution minimization methodology was developed for chemical process design using computer simulation. It is based on a pollution balance that at steady state is used to define a pollution index with units of mass of pollution per mass of products. The pollution balance has be...

  10. TRACI - THE TOOL FOR THE REDUCTION AND ASSESSMENT OF CHEMICAL AND OTHER ENVIRONMENTAL IMPACTS

    EPA Science Inventory

    TRACI, The Tool for the Reduction and Assessment of Chemical and other environmental Impacts, is described along with its history, the underlying research, methodologies, and insights within individual impact categories. TRACI facilitates the characterization of stressors that ma...

  11. GREENER CHEMICAL PROCESS DESIGN ALTERNATIVES ARE REVEALED USING THE WASTE REDUCTION DECISION SUPPORT SYSTEM (WAR DSS)

    EPA Science Inventory

    The Waste Reduction Decision Support System (WAR DSS) is a Java-based software product providing comprehensive modeling of potential adverse environmental impacts (PEI) predicted to result from newly designed or redesigned chemical manufacturing processes. The purpose of this so...

  12. Chemical reduction of europium(III) in hydrochloric acid

    SciTech Connect

    Atanasyants, A.G.; Gurinov, Yu.S.; Sofenina, E.V.

    1988-07-10

    The authors have devised a method for use at set pH and temperature, in which the volume of hydrogen produced is recorded and samples are taken for europium(II) analysis. The solution is poured into a glass cell with a thermostatic jacket; argon is passed through a capillary tube 2 for 0.5 h before the reduction is started, with the bubbling rate determined from the change in level in a burette. This burette is also used to record the hydrogen volume. The europium(II) concentration is determined by titration with potassium dichromate by a standard method. Europium is reduced by zinc in acid solution. The zinc consumption in hydrogen production can be reduced by operating at pH 2-3, with the precipitant introduced after the reaction starts.

  13. In-Situ Chemical Reduction and Oxidation of VOCs in Groundwater: Groundwater Treatability Studies

    NASA Technical Reports Server (NTRS)

    Keith, Amy; Glasgow, Jason; McCaleh, Rececca C. (Technical Monitor)

    2001-01-01

    This paper presents NASA Marshall Space Flight Center's treatability studies for volatile organic compounds in groundwater. In-Situ groundwater treatment technologies include: 1) Chemical Reduction(Ferox); 2) Chemical Oxidation (Fenton Reagents, Permanganate, and Persulfate); and 3) Thermal (Dynamic Underground Stripping, Six-Phase Heating). This paper is presented in viewgraph form.

  14. Reduction of Microbial and Chemical Contaminants in Water Using POU/POE & Mobile Treatment Technologies

    EPA Science Inventory

    POU/POE may be a cost-effective option for reductions of a particular chemical to achieve water quality compliance under certain situations and given restrictions. Proactive consumers seeking to reduce exposure to potential pathogens, trace chemicals, and nanoparticles not curre...

  15. Chemical reduction of individual graphene oxide sheets as revealed by electrostatic force microscopy.

    PubMed

    Kulkarni, Dhaval D; Kim, Songkil; Chyasnavichyus, Marius; Hu, Kesong; Fedorov, Andrei G; Tsukruk, Vladimir V

    2014-05-01

    We report continuous monitoring of heterogeneously distributed oxygenated functionalities on the entire surface of the individual graphene oxide flake during the chemical reduction process. The charge densities over the surface with mixed oxidized and graphitic domains were observed for the same flake after a step-by-step chemical reduction process using electrostatic force microscopy. Quantitative analysis revealed heavily oxidized nanoscale domains (50-100 nm across) on the graphene oxide surface and a complex reduction mechanism involving leaching of sharp oxidized asperities from the surface followed by gradual thinning and formation of uniformly mixed oxidized and graphitic domains across the entire flake.

  16. In situ chemical reduction of aquifer sediments: enhancement of reactive iron phases and TCE dechlorination.

    PubMed

    Szecsody, Jim E; Fruchter, Jonathan S; Williams, Mark D; Vermeul, Vince R; Sklarew, Debbie

    2004-09-01

    In situ chemical reduction of aquifer sediments is currently being used for chromate and TCE remediation by forming a permeable reactive barrier. The chemical and physical processes that occur during abiotic reduction of natural sediments during flow by sodium dithionite were investigated. In different aquifer sediments, 10-22% of amorphous and crystalline FeIII-oxides were dissolved/reduced, which produced primarily adsorbed FeII, and some siderite. Sediment oxidation showed predominantly one FeII phase, with a second phase being oxidized more slowly. The sediment reduction rate (3.3 h batch half-life) was chemically controlled (58 kJ mol(-1)), with some additional diffusion control during reduction in sediment columns (8.0 h half-life). It was necessary to maintain neutral to high pH to maintain reduction efficiency and prevent iron mobilization, as reduction generated H+. Sequential extractions on reduced sediment showed that adsorbed ferrous iron controlled TCE reactivity. The mass and rate of field-scale reduction of aquifer sediments were generally predicted with laboratory data using a single reduction reaction.

  17. Safety in the Chemical Laboratory--Chemical Management: A Method for Waste Reduction.

    ERIC Educational Resources Information Center

    Pine, Stanley H.

    1984-01-01

    Discusses methods for reducing or eliminating waste disposal problems in the chemistry laboratory, considering both economic and environmental aspects of the problems. Proposes inventory control, shared use, solvent recycling, zero effluent, and various means of disposing of chemicals. (JM)

  18. Recovery of Cu(II) by chemical reduction using sodium dithionite.

    PubMed

    Chou, Yi-Hsuan; Yu, Jui-Hsuan; Liang, Yang-Min; Wang, Pin-Jan; Li, Chi-Wang; Chen, Shiao-Shing

    2015-12-01

    Wastewaters containing Cu(II) along with ligands are ubiquitous in various industrial sectors. Efficacy of treatment processes for copper removal, especially precipitation, is greatly debilitated by ligands. Chemical reduction being commonly employed for production of metal nanoparticles has also been used for removing copper. Addition of ammonia was reported to be essential for improving copper reduction efficiency by increasing copper solubility at alkaline pH values. In this study, chemical reduction was employed to treat ligand-containing wastewater, exploiting the fact that ligands and metals are coexisted in many wastewaters. Result shows that copper ions were removed by either reduction or precipitation mechanisms depending on pH, type of ligands, and mixing condition. Complete copper reduction/removal was achieved under optimal condition. The lowest removal efficiency observed at pH 9.0 for ammonia system is due to formation of nano-sized particles, which are readily to pass through 0.45μm filter used for sample pretreatment before copper analysis. Instead of producing metallic copper, cuprous and copper oxide are identified in the samples collected from ammonia system and EDTA system, respectively. Re-oxidation of metallic copper particles by atmospheric oxygen during sample handling or incomplete reduction of Cu(II) ions during reduction process might be the cause. Finally, reduction process was applied to treat real wastewater, achieving complete removal of copper but only 10% of nickel. PMID:26210323

  19. Photochemical reduction of CO{sub 2} to fuels and chemicals

    SciTech Connect

    DuBois, D.; Eisenberg, R.; Fujita, E.

    1996-09-01

    Photochemical reduction of CO{sub 2} represents a potentially useful approach to developing a sustainable source of carbon-based chemicals, fuels, and materials. In this report the present status of photochemical CO{sub 2} reduction is assessed, areas that need to be better understood for advancement are identified, and approaches to overcoming barriers are suggested. Because of the interdisciplinary nature of this field, assessments of three closely interrelated areas are given including integrated photochemical systems for catalytic CO{sub 2} reduction, thermal catalytic CO{sub 2} reactions, and electrochemical CO{sub 2} reduction. The report concludes with a summary and assessment of potential impacts of this area on chemical and energy technologies.

  20. Reduction study of oxidized two-dimensional graphene-based materials by chemical and thermal reduction methods

    NASA Astrophysics Data System (ADS)

    Douglas, Amber M.

    Graphene is a two-dimensional (2D) sp2-hybridized carbon-based material possessing properties which include high electrical conductivity, ballistic thermal conductivity, tensile strength exceeding that of steel, high flexural strength, optical transparency, and the ability to adsorb and desorb atoms and molecules. Due to the characteristics of said material, graphene is a candidate for applications in integrated circuits, electrochromic devices, transparent conducting electrodes, desalination, solar cells, thermal management materials, polymer nanocomposites, and biosensors. Despite the above mentioned properties and possible applications, very few technologies have been commercialized utilizing graphene due to the high cost associated with the production of graphene. Therefore, a great deal of effort and research has been performed to produce a material that provides similar properties, reduced graphene oxide due (RGO) to the ease of commercial scaling of the production processes. This material is typically prepared through the oxidation of graphite in an aqueous media to graphene oxide (GO) followed by reduction to yield RGO. Although this material has been extensively studied, there is a lack of consistency in the scientific community regarding the analysis of the resulting RGO material. In this dissertation, a study of the reduction methods for GO and an alternate 2D carbon-based material, humic acid (HA), followed by analysis of the materials using Raman spectroscopy and Energy Dispersive X-ray Spectroscopy (EDS). Means of reduction will include chemical and thermal methods. Characterization of the material has been carried out on both before and after reduction.

  1. Reduction and solution of the chemical master equation using time scale separation and finite state projection.

    PubMed

    Peles, Slaven; Munsky, Brian; Khammash, Mustafa

    2006-11-28

    The dynamics of chemical reaction networks often takes place on widely differing time scales--from the order of nanoseconds to the order of several days. This is particularly true for gene regulatory networks, which are modeled by chemical kinetics. Multiple time scales in mathematical models often lead to serious computational difficulties, such as numerical stiffness in the case of differential equations or excessively redundant Monte Carlo simulations in the case of stochastic processes. We present a model reduction method for study of stochastic chemical kinetic systems that takes advantage of multiple time scales. The method applies to finite projections of the chemical master equation and allows for effective time scale separation of the system dynamics. We implement this method in a novel numerical algorithm that exploits the time scale separation to achieve model order reductions while enabling error checking and control. We illustrate the efficiency of our method in several examples motivated by recent developments in gene regulatory networks.

  2. Iron Isotope Fractionation Reveals Structural Change upon Microbial and Chemical Reduction of Nontronite NAu-1

    NASA Astrophysics Data System (ADS)

    Liu, K.; Wu, L.; Shi, B.; Smeaton, C. M.; Li, W.; Beard, B. L.; Johnson, C.; Roden, E. E.; Van Cappellen, P.

    2015-12-01

    Iron (Fe) isotope fractionations were determined during reduction of structural Fe(III) in nontronite NAu-1 biologically by Shewanella oneidensis MR-1 and Geobacter sulfurreducens PCA and chemically by dithionite. ~10% reduction was achieved in biological reactors, with similar reduction extents obtained by dithionite. We hypothesize that two stages occurred in our reactors. Firstly, reduction started from edge sites of clays and the produced Fe(II) partially remained in situ and partially was released into solution. Next aqueous Fe(II) adsorbed onto basal planes. The basal sorbed Fe(II) then undergoes electron transfer and atom exchange (ETAE) with octahedral Fe(III) in clays, with the most negative fractionation factor Δ56Febasal Fe(II)-structural Fe(III)of -1.7‰ when basal sorption reached a threshold value. Secondly, when the most reactive Fe(III) was exhausted, bioreduction significantly slowed down and chemical reduction was able to achieve 24% due to diffusion of small size dithionite. Importantly, no ETAE occurred between basal Fe(II) and structural Fe(III) due to blockage of pathways by collapsed clay layers. This two-stage process in our reduction experiments is distinctive from abiotic exchange experiments by mixing aqueous Fe(II) and NAu-1, where no structural change of clay would block ETAE between basal Fe(II) and structural Fe(III). The separation of reduction sites (clay edges) and sorption sites (basal planes) is unique to clay minerals with layered structure. In contrast, reduction and sorption occur on the same sites on the surfaces of Fe oxyhydroxides, where reduction does not induce structure change. Thus, the Fe isotope fractionations are the same for reduction and abiotic exchange experiments for Fe oxides. Our study reveals important changes in electron transfer and atom exchange pathways upon reduction of clay minerals by dissimilatory Fe reducing bacteria, which is prevalent in anoxic soils and sediments.

  3. ECO LOGIC INTERNATIONAL GAS-PHASE CHEMICAL REDUCTION PROCESS - THE THERMAL DESORPTION UNIT - APPLICATIONS ANALYSIS REPORT

    EPA Science Inventory

    ELI ECO Logic International, Inc.'s Thermal Desorption Unit (TDU) is specifically designed for use with Eco Logic's Gas Phase Chemical Reduction Process. The technology uses an externally heated bath of molten tin in a hydrogen atmosphere to desorb hazardous organic compounds fro...

  4. A MIXED CHEMICAL REDUCTANT FOR TREATING HEXAVALENT CHROMIUM IN A CHROMITE ORE PROCESSING SOLID WASTE

    EPA Science Inventory

    We evaluated a method for delivering ferrous iron into the subsurface to enhance chemical reduction of Cr(VI) in a chromite ore processing solid waste (COPSW). The COPSW is characterized by high pH (8.5 -11.5), high Cr(VI) concentrations in the solid phase (up to 550 mg kg-1) and...

  5. Abiotic reduction reactions of anthropogenic organic chemicals in anaerobic systems: A critical review

    NASA Astrophysics Data System (ADS)

    Macalady, Donald L.; Tratnyek, Paul G.; Grundl, Timothy J.

    1986-02-01

    This review is predicated upon the need for a detailed process-level understanding of factors influencing the reduction of anthropogenic organic chemicals in natural aquatic systems. In particular, abiotic reductions of anthropogenic organic chemicals are reviewed. The most important reductive reaction is alkyl dehalogenation (replacement of chloride with hydrogen) which occurs in organisms, sediments, sewage sludge, and reduced iron porphyrin model systems. An abiotic mechanism involving a free radical intermediate has been proposed. The abstraction of vicinal dihalides (also termed dehalogenation) is another reduction that may have an abiotic component in natural systems. Reductive dehalogenation of aryl halides has recently been reported and further study of this reaction is needed. Several other degradation reactions of organohalides that occur in anaerobic environments are mentioned, the most important of which is dehydrohalogenation. The reduction of nitro groups to amines has also been thoroughly studied. The reactions can occur abiotically, and are affected by the redox conditions of the experimental system. However, a relationship between nitro-reduction rate and measured redox potential has not been clearly established. Reductive dealkylation of the N- and O-heteroatom of hydrocarbon pollutants has been observed but not investigated in detail. Azo compounds can be reduced to their hydrazo derivatives and a thorough study of this reaction indicates that it can be caused by extracellular electron transfer agents. Quinone-hydroquinone couples are important reactive groups in humic materials and similar structures in resazurin and indigo carmine make them useful as models for environmental redox conditions. The interconversion of sulfones, sulfoxides, and sulfides is a redox process and is implicated in the degradation of several pesticides though the reactions need more study. Two reductive heterocyclic cleavage reactions are also mentioned. Finally, several

  6. Anaerobic baffled reactor coupled with chemical precipitation for treatment and toxicity reduction of industrial wastewater.

    PubMed

    Laohaprapanona, Sawanya; Marquesa, Marcia; Hogland, William

    2014-01-01

    This study describes the reduction of soluble chemical oxygen demand (CODs) and the removal of dissolved organic carbon (DOC), formaldehyde (FA) and nitrogen from highly polluted wastewater generated during cleaning procedures in wood floor manufacturing using a laboratory-scale biological anaerobic baffled reactor followed by chemical precipitation using MgCI2 .6H20 + Na2HPO4. By increasing the hydraulic retention time from 2.5 to 3.7 and 5 days, the reduction rates of FA, DOC and CODs of nearly 100%, 90% and 83%, respectively, were achieved. When the Mg:N:P molar ratio in the chemical treatment was changed from 1:1:1 to 1.3:1:1.3 at pH 8, the NH4+ removal rate increased from 80% to 98%. Biologically and chemically treated wastewater had no toxic effects on Vibrio fischeri and Artemia salina whereas chemically treated wastewater inhibited germination of Lactuca sativa owing to a high salt content. Regardless of the high conductivity of the treated wastewater, combined biological and chemical treatment was found to be effective for the removal of the organic load and nitrogen, and to be simple to operate and to maintain. A combined process such as that investigated could be useful for on-site treatment of low volumes of highly polluted wastewater generated by the wood floor and wood furniture industries, for which there is no suitable on-site treatment option available today.

  7. Development Of Chemical Reduction And Air Stripping Processes To Remove Mercury From Wastewater

    SciTech Connect

    Jackson, Dennis G.; Looney, Brian B.; Craig, Robert R.; Thompson, Martha C.; Kmetz, Thomas F.

    2013-07-10

    This study evaluates the removal of mercury from wastewater using chemical reduction and air stripping using a full-scale treatment system at the Savannah River Site. The existing water treatment system utilizes air stripping as the unit operation to remove organic compounds from groundwater that also contains mercury (C ~ 250 ng/L). The baseline air stripping process was ineffective in removing mercury and the water exceeded a proposed limit of 51 ng/L. To test an enhancement to the existing treatment modality a continuous dose of reducing agent was injected for 6-hours at the inlet of the air stripper. This action resulted in the chemical reduction of mercury to Hg(0), a species that is removable with the existing unit operation. During the injection period a 94% decrease in concentration was observed and the effluent satisfied proposed limits. The process was optimized over a 2-day period by sequentially evaluating dose rates ranging from 0.64X to 297X stoichiometry. A minimum dose of 16X stoichiometry was necessary to initiate the reduction reaction that facilitated the mercury removal. Competing electron acceptors likely inhibited the reaction at the lower 1 doses, which prevented removal by air stripping. These results indicate that chemical reduction coupled with air stripping can effectively treat large-volumes of water to emerging part per trillion regulatory standards for mercury.

  8. Fundamental limits on gas-phase chemical reduction of NOx in a plasma

    SciTech Connect

    Penetrante, B.M.; Hsiao, M.C.; Merritt, B.T.; Vogtlin, G.E.

    1997-12-31

    In the plasma, the electrons do not react directly with the NOx molecules. The electrons collide mainly with the background gas molecules like N{sub 2}, O{sub 2} and H{sub 2}O. Electron impact on these molecules result partly in dissociation reactions that produce reactive species like N, O and OH. The NOx in the engine exhaust gas initially consist mostly of NO. The ground state nitrogen atom, N, is the only species that could lead to the chemical reduction of NO to N{sub 2}. The O radical oxidizes NO to NO{sub 2} leaving the same amount of NOx. The OH radical converts NO{sub 2} to nitric acid. Acid products in the plasma can easily get adsorbed on surfaces in the plasma reactor and in the pipes. When undetected, the absence of these oxidation products can often be mistaken for chemical reduction of NOx. In this paper the authors will examine the gas-phase chemical reduction of NOx. They will show that under the best conditions, the plasma can chemically reduce 1.6 grams of NOx per brake-horsepower-hour [g(NOx)/bhp-hr] when 5% of the engine output energy is delivered to the plasma.

  9. Performance of two swine manure treatment systems on chemical composition and on the reduction of pathogens.

    PubMed

    Viancelli, A; Kunz, A; Steinmetz, R L R; Kich, J D; Souza, C K; Canal, C W; Coldebella, A; Esteves, P A; Barardi, C R M

    2013-01-01

    Swine effluents must be correctly handled to avoid negative environmental impacts. In this study, the profiles of two swine manure treatment systems were evaluated: a solid-liquid separation step, followed by an anaerobic reactor, and an aerobic step (System 1); and a biodigester followed by serial lagoons (System 2). Both systems were described by the assessment of chemical, bacterial and viral parameters. The results showed that in System 1, there was reduction of chemicals (COD, phosphorus, total Kjeldhal nitrogen - TKN - and NH(3)), total coliforms and Escherichia coli; however, the same reduction was not observed for Salmonella sp. Viral particles were significantly reduced but not totally eliminated from the effluent. In System 2, there was a reduction of chemicals, bacteria and viruses with no detection of Salmonella sp., circovirus, parvovirus, and torque teno virus in the effluent. The chemical results indicate that the treated effluent can be reused for cleaning swine facilities. However, the microbiological results show a need of additional treatment to achieve a complete inactivation for cases when direct contact with animals is required.

  10. Synthesis of cuprous oxide nanocomposite electrodes by room-temperature chemical partial reduction.

    PubMed

    Park, Kyung-Soo; Seo, Seung-Deok; Jin, Yun-Ho; Lee, Seung-Hun; Shim, Hyun-Woo; Lee, Du-Hee; Kim, Dong-Wan

    2011-10-01

    We demonstrate a template-free synthetic approach for the preparation of a highly conductive Cu/Cu(2)O nanocomposite electrode by a chemical reduction process. Cu(2)O octahedra were prepared through chemical dehydrogenation of as-synthesized Cu(OH)(2) nanowire precursors. To provide a sufficiently electron-conducting network, the Cu(2)O particles were transformed into Cu/Cu(2)O nanocomposites by an intentional reduction process. The Cu/Cu(2)O nanocomposite electrodes showed enhanced cycling performance compared to Cu(2)O particles. Furthermore, their rate capabilities were superior to those of their mechanically mixed Cu/Cu(2)O counterparts. This enhanced electrochemical performance of the hybrid Cu/Cu(2)O nanocomposites was ascribed to the formation of homogeneous nanostructures, offering an efficient electron-transport path provided by the presence of highly dispersed Cu nanoparticles. PMID:21850303

  11. Solid-phase reduction of Cr2O3 under chemical catalytic conditions

    NASA Astrophysics Data System (ADS)

    Simonov, V. K.; Grishin, A. M.

    2016-06-01

    The kinetics of the solid-phase reduction of Cr2O3 with carbon under chemical catalytic action on the reacting system is studied. A significant intensification of the process in the presence of small amounts of potassium and sodium salts is established. The concepts of the catalyst action mechanism are considered and experimentally substantiated. Manufacture of iron-chromium master alloys with a restricted content of carbon can be organized at low temperatures, and they can be used in steelmaking.

  12. Sulfa Drugs Inhibit Sepiapterin Reduction and Chemical Redox Cycling by Sepiapterin Reductase

    PubMed Central

    Yang, Shaojun; Jan, Yi-Hua; Mishin, Vladimir; Richardson, Jason R.; Hossain, Muhammad M.; Heindel, Ned D.; Heck, Diane E.; Laskin, Debra L.

    2015-01-01

    Sepiapterin reductase (SPR) catalyzes the reduction of sepiapterin to dihydrobiopterin (BH2), the precursor for tetrahydrobiopterin (BH4), a cofactor critical for nitric oxide biosynthesis and alkylglycerol and aromatic amino acid metabolism. SPR also mediates chemical redox cycling, catalyzing one-electron reduction of redox-active chemicals, including quinones and bipyridinium herbicides (e.g., menadione, 9,10-phenanthrenequinone, and diquat); rapid reaction of the reduced radicals with molecular oxygen generates reactive oxygen species (ROS). Using recombinant human SPR, sulfonamide- and sulfonylurea-based sulfa drugs were found to be potent noncompetitive inhibitors of both sepiapterin reduction and redox cycling. The most potent inhibitors of sepiapterin reduction (IC50s = 31–180 nM) were sulfasalazine, sulfathiazole, sulfapyridine, sulfamethoxazole, and chlorpropamide. Higher concentrations of the sulfa drugs (IC50s = 0.37–19.4 μM) were required to inhibit redox cycling, presumably because of distinct mechanisms of sepiapterin reduction and redox cycling. In PC12 cells, which generate catecholamine and monoamine neurotransmitters via BH4-dependent amino acid hydroxylases, sulfa drugs inhibited both BH2/BH4 biosynthesis and redox cycling mediated by SPR. Inhibition of BH2/BH4 resulted in decreased production of dopamine and dopamine metabolites, 3,4-dihydroxyphenylacetic acid and homovanillic acid, and 5-hydroxytryptamine. Sulfathiazole (200 μM) markedly suppressed neurotransmitter production, an effect reversed by BH4. These data suggest that SPR and BH4-dependent enzymes, are “off-targets” of sulfa drugs, which may underlie their untoward effects. The ability of the sulfa drugs to inhibit redox cycling may ameliorate ROS-mediated toxicity generated by redox active drugs and chemicals, contributing to their anti-inflammatory activity. PMID:25550200

  13. Sulfa drugs inhibit sepiapterin reduction and chemical redox cycling by sepiapterin reductase.

    PubMed

    Yang, Shaojun; Jan, Yi-Hua; Mishin, Vladimir; Richardson, Jason R; Hossain, Muhammad M; Heindel, Ned D; Heck, Diane E; Laskin, Debra L; Laskin, Jeffrey D

    2015-03-01

    Sepiapterin reductase (SPR) catalyzes the reduction of sepiapterin to dihydrobiopterin (BH2), the precursor for tetrahydrobiopterin (BH4), a cofactor critical for nitric oxide biosynthesis and alkylglycerol and aromatic amino acid metabolism. SPR also mediates chemical redox cycling, catalyzing one-electron reduction of redox-active chemicals, including quinones and bipyridinium herbicides (e.g., menadione, 9,10-phenanthrenequinone, and diquat); rapid reaction of the reduced radicals with molecular oxygen generates reactive oxygen species (ROS). Using recombinant human SPR, sulfonamide- and sulfonylurea-based sulfa drugs were found to be potent noncompetitive inhibitors of both sepiapterin reduction and redox cycling. The most potent inhibitors of sepiapterin reduction (IC50s = 31-180 nM) were sulfasalazine, sulfathiazole, sulfapyridine, sulfamethoxazole, and chlorpropamide. Higher concentrations of the sulfa drugs (IC50s = 0.37-19.4 μM) were required to inhibit redox cycling, presumably because of distinct mechanisms of sepiapterin reduction and redox cycling. In PC12 cells, which generate catecholamine and monoamine neurotransmitters via BH4-dependent amino acid hydroxylases, sulfa drugs inhibited both BH2/BH4 biosynthesis and redox cycling mediated by SPR. Inhibition of BH2/BH4 resulted in decreased production of dopamine and dopamine metabolites, 3,4-dihydroxyphenylacetic acid and homovanillic acid, and 5-hydroxytryptamine. Sulfathiazole (200 μM) markedly suppressed neurotransmitter production, an effect reversed by BH4. These data suggest that SPR and BH4-dependent enzymes, are "off-targets" of sulfa drugs, which may underlie their untoward effects. The ability of the sulfa drugs to inhibit redox cycling may ameliorate ROS-mediated toxicity generated by redox active drugs and chemicals, contributing to their anti-inflammatory activity.

  14. Sulfa drugs inhibit sepiapterin reduction and chemical redox cycling by sepiapterin reductase.

    PubMed

    Yang, Shaojun; Jan, Yi-Hua; Mishin, Vladimir; Richardson, Jason R; Hossain, Muhammad M; Heindel, Ned D; Heck, Diane E; Laskin, Debra L; Laskin, Jeffrey D

    2015-03-01

    Sepiapterin reductase (SPR) catalyzes the reduction of sepiapterin to dihydrobiopterin (BH2), the precursor for tetrahydrobiopterin (BH4), a cofactor critical for nitric oxide biosynthesis and alkylglycerol and aromatic amino acid metabolism. SPR also mediates chemical redox cycling, catalyzing one-electron reduction of redox-active chemicals, including quinones and bipyridinium herbicides (e.g., menadione, 9,10-phenanthrenequinone, and diquat); rapid reaction of the reduced radicals with molecular oxygen generates reactive oxygen species (ROS). Using recombinant human SPR, sulfonamide- and sulfonylurea-based sulfa drugs were found to be potent noncompetitive inhibitors of both sepiapterin reduction and redox cycling. The most potent inhibitors of sepiapterin reduction (IC50s = 31-180 nM) were sulfasalazine, sulfathiazole, sulfapyridine, sulfamethoxazole, and chlorpropamide. Higher concentrations of the sulfa drugs (IC50s = 0.37-19.4 μM) were required to inhibit redox cycling, presumably because of distinct mechanisms of sepiapterin reduction and redox cycling. In PC12 cells, which generate catecholamine and monoamine neurotransmitters via BH4-dependent amino acid hydroxylases, sulfa drugs inhibited both BH2/BH4 biosynthesis and redox cycling mediated by SPR. Inhibition of BH2/BH4 resulted in decreased production of dopamine and dopamine metabolites, 3,4-dihydroxyphenylacetic acid and homovanillic acid, and 5-hydroxytryptamine. Sulfathiazole (200 μM) markedly suppressed neurotransmitter production, an effect reversed by BH4. These data suggest that SPR and BH4-dependent enzymes, are "off-targets" of sulfa drugs, which may underlie their untoward effects. The ability of the sulfa drugs to inhibit redox cycling may ameliorate ROS-mediated toxicity generated by redox active drugs and chemicals, contributing to their anti-inflammatory activity. PMID:25550200

  15. Prospective life cycle assessment of graphene production by ultrasonication and chemical reduction.

    PubMed

    Arvidsson, Rickard; Kushnir, Duncan; Sandén, Björn A; Molander, Sverker

    2014-04-15

    One promising future bulk application of graphene is as composite additive. Therefore, we compare two production routes for in-solution graphene using a cradle-to-gate lifecycle assessment focusing on potential differences in energy use, blue water footprint, human toxicity, and ecotoxicity. The data used for the assessment is based on information in scientific papers and patents. Considering the prospective nature of this study, environmental impacts from background systems such as energy production were not included. The production routes are either based on ultrasonication or chemical reduction. The results show that the ultrasonication route has lower energy and water use, but higher human and ecotoxicity impacts, compared to the chemical reduction route. However, a sensitivity analysis showed that solvent recovery in the ultrasonication process gives lower impacts for all included impact categories. The sensitivity analysis also showed that solvent recovery is important to lower the blue water footprint of the chemical reduction route as well. The results demonstrate the possibility to conduct a life cycle assessment study based mainly on information from patents and scientific articles, enabling prospective life cycle assessment studies of products at early stages of technological development.

  16. Are sulfur isotope ratios sufficient to determine the antiquity of sulfate reduction. [implications for chemical evolution

    NASA Technical Reports Server (NTRS)

    Ashendorf, D.

    1980-01-01

    Possible limitations on the use of sulfur isotope ratios in sedimentary sulfides to infer the evolution of microbial sulfate reduction are discussed. Current knowledge of the ways in which stable sulfur isotope ratios are altered by chemical and biological processes is examined, with attention given to the marine sulfur cycle involving various microbial populations, and sulfur reduction processes, and it is noted that satisfactory explanations of sulfur isotope ratios observed in live organisms and in sediments are not yet available. It is furthermore pointed out that all members of the same genus of sulfate reducing bacteria do not always fractionate sulfur to the same extent, that the extent of sulfur fractionation by many sulfate-reducing organisms has not yet been determined, and that inorganic processes can also affect sulfur isotope fractionation values. The information currently available is thus concluded to be insufficient to determine the time of initial appearance of biological sulfate reduction.

  17. Ultralow Level Mercury Treatment Using Chemical Reduction and Air Stripping: Scoping Report

    SciTech Connect

    Looney, B.B.

    2000-08-18

    Data collected during the first stage of a Savannah River Technology Center (SRTC) Strategic Research and Development Project confirmed the efficacy of chemical reduction and air stripping/sparging as an ultralow level mercury treatment concept for waters containing Hg(II). The process consists of dosing the water with low levels of stannous chloride to convert the mercury to Hg. This form of mercury can easily be removed from the water by air stripping or sparging. Samples of Savannah River Site (SRS) groundwater containing approximately 130 ng/L of total mercury (as Hg(II)) were used for the study. In undosed samples, sparging removed 0 percent of the initial mercury. In the dosed samples, all of the removals were greater than 94 percent, except in one water type at one dose. This sample, which was saturated with dissolved oxygen, showed a 63 percent reduction in mercury following treatment at the lowest dose. Following dosing at minimally effective levels and sparging, treated water contained less than 10 ng/L total mercury. In general, the data indicate that the reduction of mercury is highly favored and that stannous chloride reagent efficiently targets the Hg(II) contaminant in the presence of competing reactions. Based on the results, the authors estimated that the costs of implementing and operating an ultralow level mercury treatment process based on chemical reduction and stripping/sparging are 10 percent to 20 percent of traditional treatment technologies.

  18. Influence of physical and chemical aquifer heterogeneity on nitrate reduction processes by numerical simulations

    NASA Astrophysics Data System (ADS)

    Kalbacher, T.; Jang, E.; He, W.; Savoy, H.; Schueth, C.; Kolditz, O.

    2015-12-01

    Nitrate reduction reactions, as one of the most important redox reactions in a subsurface system, are strongly influenced by various heterogeneity factors which influence transport of chemical species and spatial distribution of redox substances and consequently have an effect on overall nitrate reduction capacity. In this presented work, the influence of two heterogeneity factors, spatially heterogeneity of hydrological parameters versus spatial heterogeneity of geochemical reactive substances distribution, are discussed with a focus on nitrate transport and redox transformation processes. For this purpose, a coupling interface OGS#IPhreeqc is employed. This code combines Finite-Element groundwater flow and multi-species transport code of OpenGeoSys (OGS) with the IPhreeqc module of open source geochemical solver PHREEQC. The resulting coupled model is applied for simulation of nitrate reduction processes with a series of hypothetical aquifer systems, built using exponentially-correlated log-normal distributed hydraulic conductivity and reactive substances. The spatially heterogeneous aquifer system is realized by a RandomFields package using a statistical program R. Results show that the heterogeneous hydraulics conductivity field has larger impact on nitrate reduction capacity than heterogeneous reactive substances distribution. Moreover, nitrate reduction capacity can be increased by enhanced mixing in heterogeneous hydraulic conductivity field however its overall reduction capacity has gradually decreased as a degree of heterogeneity has increased since accessibility of the chemical species by the reactive substances may be limited. These results support that appropriate characterization of the variance of hydraulic conductivity within the aquifer is important to predict contaminant fate and transport and quantify the impact of uncertainty on numerical groundwater simulation.

  19. Removal of PCBs in contaminated soils by means of chemical reduction and advanced oxidation processes.

    PubMed

    Rybnikova, V; Usman, M; Hanna, K

    2016-09-01

    Although the chemical reduction and advanced oxidation processes have been widely used individually, very few studies have assessed the combined reduction/oxidation approach for soil remediation. In the present study, experiments were performed in spiked sand and historically contaminated soil by using four synthetic nanoparticles (Fe(0), Fe/Ni, Fe3O4, Fe3 - x Ni x O4). These nanoparticles were tested firstly for reductive transformation of polychlorinated biphenyls (PCBs) and then employed as catalysts to promote chemical oxidation reactions (H2O2 or persulfate). Obtained results indicated that bimetallic nanoparticles Fe/Ni showed the highest efficiency in reduction of PCB28 and PCB118 in spiked sand (97 and 79 %, respectively), whereas magnetite (Fe3O4) exhibited a high catalytic stability during the combined reduction/oxidation approach. In chemical oxidation, persulfate showed higher PCB degradation extent than hydrogen peroxide. As expected, the degradation efficiency was found to be limited in historically contaminated soil, where only Fe(0) and Fe/Ni particles exhibited reductive capability towards PCBs (13 and 18 %). In oxidation step, the highest degradation extents were obtained in presence of Fe(0) and Fe/Ni (18-19 %). The increase in particle and oxidant doses improved the efficiency of treatment, but overall degradation extents did not exceed 30 %, suggesting that only a small part of PCBs in soil was available for reaction with catalyst and/or oxidant. The use of organic solvent or cyclodextrin to improve the PCB availability in soil did not enhance degradation efficiency, underscoring the strong impact of soil matrix. Moreover, a better PCB degradation was observed in sand spiked with extractable organic matter separated from contaminated soil. In contrast to fractions with higher particle size (250-500 and <500 μm), no PCB degradation was observed in the finest fraction (≤250 μm) having higher organic matter content. These findings

  20. Strategies for emission reduction of air pollutants produced from a chemical plant.

    PubMed

    Lee, Byeong-Kyu; Cho, Sung-Woong

    2003-01-01

    Various air pollution control (APC) techniques were employed in order to reduce emissions of air pollutants produced from chemical plants, which have many different chemical production facilities. For an emission reduction of acid gases, this study employed a method to improve solubility of pollutants by decreasing the operating temperature of the scrubbers, increasing the surface area for effective contact of gas and liquid, and modifying processes in the acid scrubbers. To reduce emission of both amines and acid gases, pollutant gas components were first separated, then condensation and/or acid scrubbing, depending on the chemical and physical properties of pollutant components, were used. To reduce emission of solvents, condensation and activated carbon adsorption were employed. To reduce emission of a mixture gases containing acid gases and solvents, the mixed gases were passed into the first condenser, the acid scrubber, the second condenser, and the activated carbon adsorption tower in sequence. As a strategy to reduce emission of pollutants at the source, this study also employed the simple pollution prevention concept of modification of the previously operating APC control device. Finally, air emissions of pollutants produced from the chemical plants were much more reduced by applying proper APC methods, depending upon the types (physical or chemical properties) and the specific emission situations of pollutants. PMID:12447574

  1. Efficient parametric analysis of the chemical master equation through model order reduction

    PubMed Central

    2012-01-01

    Background Stochastic biochemical reaction networks are commonly modelled by the chemical master equation, and can be simulated as first order linear differential equations through a finite state projection. Due to the very high state space dimension of these equations, numerical simulations are computationally expensive. This is a particular problem for analysis tasks requiring repeated simulations for different parameter values. Such tasks are computationally expensive to the point of infeasibility with the chemical master equation. Results In this article, we apply parametric model order reduction techniques in order to construct accurate low-dimensional parametric models of the chemical master equation. These surrogate models can be used in various parametric analysis task such as identifiability analysis, parameter estimation, or sensitivity analysis. As biological examples, we consider two models for gene regulation networks, a bistable switch and a network displaying stochastic oscillations. Conclusions The results show that the parametric model reduction yields efficient models of stochastic biochemical reaction networks, and that these models can be useful for systems biology applications involving parametric analysis problems such as parameter exploration, optimization, estimation or sensitivity analysis. PMID:22748204

  2. An efficient error-propagation-based reduction method for large chemical kinetic mechanisms

    SciTech Connect

    Pepiot-Desjardins, P.; Pitsch, H.

    2008-07-15

    Production rates obtained from a detailed chemical mechanism are analyzed in order to quantify the coupling between the various species and reactions involved. These interactions can be represented by a directed relation graph. A geometric error propagation strategy applied to this graph accurately identifies the dependencies of specified targets and creates a set of increasingly simplified kinetic schemes containing only the chemical paths deemed the most important for the targets. An integrity check is performed concurrently with the reduction process to avoid truncated chemical paths and mass accumulation in intermediate species. The quality of a given skeletal model is assessed through the magnitude of the errors introduced in the target predictions. The applied error evaluation is variable-dependent and unambiguous for unsteady problems. The technique yields overall monotonically increasing errors, and the smallest skeletal mechanism that satisfies a user-defined error tolerance over a selected domain of applicability is readily obtained. An additional module based on life-time analysis identifies a set of species that can be modeled accurately by quasi-steady state relations. An application of the reduction procedure is presented for autoignition using a large iso-octane mechanism. The whole process is automatic, is fast, has moderate CPU and memory requirements, and compares favorably to other existing techniques. (author)

  3. Synthesis of Hierarchical Nanoporous Microstructures via the Kirkendall Effect in Chemical Reduction Process.

    PubMed

    Gao, Ling; Pang, Chao; He, Dafang; Shen, Liming; Gupta, Arunava; Bao, Ningzhong

    2015-01-01

    A series of novel hierarchical nanoporous microstructures have been synthesized through one-step chemical reduction of micron size Cu2O and Co3O4 particles. By controlling the reduction time, non-porous Cu2O microcubes sequentially transform to nanoporous Cu/Cu2O/Cu dented cubic composites and hollow eightling-like Cu microparticles. The mechanism involved in the complex structural evolution is explained based on oxygen diffusion and Kirkendall effect. The nanoporous Cu/Cu2O/Cu dented cubic composites exhibit superior electrochemical performance as compared to solid Cu2O microcubes. The reduction of nonporous Co3O4 also exhibits a uniform sequential reduction process from nonporous Co3O4 to porous Co3O4/CoO composites, porous CoO, porous CoO/Co composites, and porous foam-like Co particles. Nanoscale channels originate from the particle surface and eventually develop inside the entire product, resulting in porous foam-like Co microparticles. The Kirkendall effect is believed to facilitate the formation of porous structures in both processes. PMID:26552845

  4. Synthesis of Hierarchical Nanoporous Microstructures via the Kirkendall Effect in Chemical Reduction Process

    PubMed Central

    Gao, Ling; Pang, Chao; He, Dafang; Shen, Liming; Gupta, Arunava; Bao, Ningzhong

    2015-01-01

    A series of novel hierarchical nanoporous microstructures have been synthesized through one-step chemical reduction of micron size Cu2O and Co3O4 particles. By controlling the reduction time, non-porous Cu2O microcubes sequentially transform to nanoporous Cu/Cu2O/Cu dented cubic composites and hollow eightling-like Cu microparticles. The mechanism involved in the complex structural evolution is explained based on oxygen diffusion and Kirkendall effect. The nanoporous Cu/Cu2O/Cu dented cubic composites exhibit superior electrochemical performance as compared to solid Cu2O microcubes. The reduction of nonporous Co3O4 also exhibits a uniform sequential reduction process from nonporous Co3O4 to porous Co3O4/CoO composites, porous CoO, porous CoO/Co composites, and porous foam-like Co particles. Nanoscale channels originate from the particle surface and eventually develop inside the entire product, resulting in porous foam-like Co microparticles. The Kirkendall effect is believed to facilitate the formation of porous structures in both processes. PMID:26552845

  5. Synthesis of Hierarchical Nanoporous Microstructures via the Kirkendall Effect in Chemical Reduction Process

    NASA Astrophysics Data System (ADS)

    Gao, Ling; Pang, Chao; He, Dafang; Shen, Liming; Gupta, Arunava; Bao, Ningzhong

    2015-11-01

    A series of novel hierarchical nanoporous microstructures have been synthesized through one-step chemical reduction of micron size Cu2O and Co3O4 particles. By controlling the reduction time, non-porous Cu2O microcubes sequentially transform to nanoporous Cu/Cu2O/Cu dented cubic composites and hollow eightling-like Cu microparticles. The mechanism involved in the complex structural evolution is explained based on oxygen diffusion and Kirkendall effect. The nanoporous Cu/Cu2O/Cu dented cubic composites exhibit superior electrochemical performance as compared to solid Cu2O microcubes. The reduction of nonporous Co3O4 also exhibits a uniform sequential reduction process from nonporous Co3O4 to porous Co3O4/CoO composites, porous CoO, porous CoO/Co composites, and porous foam-like Co particles. Nanoscale channels originate from the particle surface and eventually develop inside the entire product, resulting in porous foam-like Co microparticles. The Kirkendall effect is believed to facilitate the formation of porous structures in both processes.

  6. Chemical and hemolytic properties of sphingolipids modified by ozonolysis and reduction.

    PubMed

    Uemura, K; Hara, A; Taketomi, T

    1976-06-01

    Various sphingolipids were chemically modified in their sphingosine base by ozonolysis and reduction. The derivatives obtained from Forssman globoside, globoside I, galactosyl ceramide, and sphingomyelin were purified and all were found to be hemolytic. The presence of cholesterol could inhibit this activity. The simultaneous cleavage at a double bond in the fatty acid as well as in the sphingosine of Forssman globoside resulted in the formation of a more polar compound with no detectable hemolytic activity. The haptenic reactivity was retained after ozonolysis and reduction of Forssman globoside, as shown by precipitin line formation in agar gel with appropriate antibodies. The results indicate that this modification procedure may be useful in studies of the physiological and immunological properties of sphingolipids.

  7. Synthesis and spectroscopic characterization of gold nanobipyramids prepared by a chemical reduction method

    NASA Astrophysics Data System (ADS)

    Thanh Ngo, Vo Ke; Phat Huynh, Trong; Giang Nguyen, Dang; Phuong Uyen Nguyen, Hoang; Lam, Quang Vinh; Dat Huynh, Thanh

    2015-12-01

    Gold nanobipyramids (NBPs) have attracted much attention because they have potential for applications in smart sensing devices, such as medical diagnostic equippments. This is due to the fact that they show more advantageous plasmonic properties than other gold nanostructures. We describe a chemical reduction method for synthesizing NBPs using conventional heating with ascorbic acid reduction and cetyltrimethylamonium bromide (CTAB) + AgNO3 as capping agents. The product was characterized by ultraviolet-visible spectroscopy (UV-vis), Fourier transmission infrared spectroscopy (FTIR), transmission electron microscopy (TEM), x-ray powder diffraction (XRD). The results showed that gold nanoparticles were formed with bipyramid shape (tip-to-tip distance of 88.4 ± 9.4 nm and base length of 29.9 ± 3.2 nm) and face-centered-cubic crystalline structure. Optimum parameters for preparation of NBPs are also found.

  8. Synthesis of high magnetization Fe and FeCo nanoparticles by high temperature chemical reduction

    SciTech Connect

    Kandapallil, B; Colborn, RE; Bonitatibus, PJ; Johnson, F

    2015-03-15

    Fe and FeCo ferromagnetic nanoparticles in the 5-10 nm size regimes featuring high magnetization were synthesized using a modified chemical reduction method. The structure and morphology of these nanoparticles were confirmed by XRD and TOM analysis. These small, monodisperse and phase pure nanoparticles exhibited magnetic saturation of 210 emu/g (Fe) and 220 emu/g (Fe+Co) for Fe and FeCo nanoparticles respectively. The magnetization was found to be dependent on the temperature at which the reducing agent was introduced. (C) 2014 Elsevier B.V. All rights reserved,

  9. Reduction of WO 3 to nano-WC by thermo-chemical reaction route

    NASA Astrophysics Data System (ADS)

    Kumar, Akshay; Singh, K.; Pandey, O. P.

    2009-02-01

    Thermo-chemical reaction route has been used to synthesize WC-nanoparticles from WO 3. Two different carbon sources are used to study the effect of these sources on synthesis. The as-prepared samples are characterized by using X-ray diffraction (XRD), differential thermal analyzer (DTA), thermo-gravimetric analysis (TGA) and transmission electron microscope (TEM). The results indicate that reduction of WO 3 to WC takes place by the adsorption of carbon at the surface of WO 3 forming porous structure at the defect sites through which carbon diffuses. As the concentration of adsorbed carbon increases the growth of carbon nanotube starts from this site which ultimately gets converted to carbon nano-fibers of higher chemical activity.

  10. Plasma-Chemical Hybrid NOx Reduction System for Commercial Cogeneration Boiler

    NASA Astrophysics Data System (ADS)

    Kuroki, Tomoyuki; Fujishima, Hidekatsu; Okubo, Masaaki

    Operation tests of the smoke-tube boiler emission NOx treatment plant which consists of a plasma ozonizer using a pressure swing adsorption (PSA) oxygen generator and silent discharge for indirect NO oxidation and a Na2SO3 chemical scrubber are carried out for cogeneration boilers which uses a city gas and heavy oil as a fuel based on our proposed plasma-chemical hybrid NOx reduction principle. It is clear that amount of NO removed is almost same as the amount of corresponding O3 concentration to oxidize NO regardless of fuels and flow rates of flue gas. After the relation between oxidation-reduction potential (ORP) and the NOx removal efficiency is obtained, continuous operation tests of this plant are performed. For gas firing boiler emission, the NO complete removal and the decrease in NOx from 32 ppm to 3 ppm are achieved for 300 min by keeping -30 mV of ORP. For the treatment of heavy oil boiler emission, the decrease in NOx from 90 ppm to less than 25 ppm is maintained for 250 min. It is demonstrated that the high NOx removal performance can be maintained for a long time by keeping the optimum value of ORP.

  11. Recovery of metallic copper by integrated chemical reduction and high gradient magnetic separation.

    PubMed

    Wu, Wan-I; Panchangam, Sri Chandana; Wu, Chung-Hsin; Hong, Andy P K; Lin, Cheng-Fang

    2011-01-01

    The recovery of metals from waste effluents is necessary for pollution prevention and sustainable practice. High gradient magnetic separation (HGMS) is seen as a viable method. We investigated the capture of valence copper from aqueous copper ion by HGMS in combination with a chemical reduction process. When a copper solution (3.9 or 15.6 mM) was exposed to excess of dithionite (mole ratio of 1:3) in the presence of ammonia (mole ratio of 4) and amended with MnCl2 (2.5 g/L) and the mixture passed through a flow reactor under a strong magnetic field (10000 Gauss), valence copper was obtained and captured in the reactor with well over 95% yields. The chemical reduction reactions were unaffected by the presence of MnCl2 while the amount of MnCl2 (0, 20 and 32 mM) has significantly varied the copper recovery efficiency, especially in the case of high initial copper ion concentration (15.6 mM). Formation of MnO2 flocs was found to have a detrimental effect on copper removal efficiency. The HGMS method offers a tool of resource recovery for copper from waste effluents.

  12. IF-WS{sub 2} nanoparticles size design and synthesis via chemical reduction

    SciTech Connect

    Ghoreishi, S.M.; Meshkat, S.S.; Dadkhah, A.A.

    2010-05-15

    An innovative synthesis of inorganic fullerene-like disulfide tungsten (IF-WS{sub 2}) nanoparticles was developed using a chemical reduction reaction in a horizontal quartz reactor. In this process, first tungsten trisulfide (WS{sub 3}) was formed via a chemical reaction of tetra thiotungstate ammonium ((NH{sub 4}){sub 2}WS{sub 4}), polyethylene glycol (PEG), and hydrochloric acid (HCl) at ambient temperature and pressure. Subsequently, WS{sub 3} was reacted with hydrogen (H{sub 2}) at high temperature (1173-1373 K) in a quartz tube. The produced WS{sub 2} nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDAX), and transmission electron microscopy (TEM). The characterization results indicated that the high-purity (100%) IF-WS{sub 2} nanoparticles were produced. Moreover, addition of surfactant (PEG) and higher operating temperature (1173-1373 K) decreased the particles agglomeration, and consequently led to the reduction of average diameter of WS{sub 2} particles in the range of 50-78 nm. The developed method is simple, environmentally compatible, and cost-effective in contrast to the conventional techniques.

  13. Visible light Cr(VI) reduction and organic chemical oxidation by TiO2 photocatalysis.

    PubMed

    Sun, Bo; Reddy, Ettireddy P; Smirniotis, Panagiotis G

    2005-08-15

    Here we report the simultaneous Cr(VI) reduction and 4-chlorophenol (4-CP) oxidation in water under visible light (wavelength > 400 nm) using commercial Degussa P25 TiO2. This remarkable observation was attributed to a synergistic effect among TiO2, Cr(VI), and 4-CP. It is well known that TiO2 alone cannot remove either 4-CP or Cr(VI) efficiently under visible light. Moreover, the interaction between Cr(VI) and 4-CP is minimal if not negligible. However, we found that the combination of TiO2, Cr(VI), and 4-CP together can enable efficient Cr(VI) reduction and 4-CP oxidation under visible light. The specific roles of the three ingredients in the synergistic system were studied parametrically. It was found that optimal concentrations of Cr(VI) and TiO2 exist for the Cr(VI) reduction and 4-CP oxidation. Cr(VI) was compared experimentally with other metals such as Cu(ll), Fe(lll), Mn(IV), Ce(IV), and V(V). Among all these metal ions, only Cr(VI) promotes the photocatalytic oxidation of 4-CP. The amount of 4-CP removed was directly related to the initial concentration of Cr(VI). The system was also tested with four other chemicals (aniline, salicylic acid, formic acid, and diethyl phosphoramidate). We found that the same phenomenon occurred for organics containing acid and/or phenolic groups. Cr(VI) was reduced at the same time as the organic chemicals being oxidized during photoreaction under visible light. The synergistic effect was also found with pure anatase TiO2 and rutile TiO2. This study demonstrates a possible economical way for environmental cleanup under visible light.

  14. Reduction of chemical oxygen demand of industrial wastes using subcritical water oxidation

    SciTech Connect

    Lin, J.C.; Chang, C.J. )

    1992-10-01

    If wastes have strong toxicity, high organic content, and a deep hue, they are difficult to handle in the waste disposal. It is very practical that waste of this kind is treated by Subcritical Water Oxidation (SWO). In our work, caprolactum (CPL) waste, purged from a petrochemical plant, and dyeing waste, purged from a textile plant, were individually treated by a semi-batch SWO process. Within a one-hour treatment, Chemical Oxygen Demand (COD) reduction reached 89% for CPL waste (6.90 MPa, 260[degree]C) and 95% for dyeing waste (6.90 MPa, 240[degree]C). There is also a great improvement in hue, especially for the dyeing waste. When CPL wastewater was treated by the SWO process using a chromium metal powder as a catalyst, COD reduction improved further under the same operating conditions. A kinetic model was used to illustrate the oxidation mechanism and the effectiveness of the catalyst. The oxygen concentration in the effluent showed that oxygen consumption corresponded to COD reduction. With the monitoring of concentrations of total soluble chromium in the effluent, a suitable reaction period could be found in order to meet the standard of the Environmental Protection Agency (EPA). 12 refs., 11 figs., 2 tabs.

  15. Bridging organometallics and quantum chemical topology: Understanding electronic relocalisation during palladium-catalyzed reductive elimination.

    PubMed

    de Courcy, Benoit; Derat, Etienne; Piquemal, Jean-Philip

    2015-06-01

    This article proposes to bridge two fields, namely organometallics and quantum chemical topology. To do so, Palladium-catalyzed reductive elimination is studied. Such reaction is a classical elementary step in organometallic chemistry, where the directionality of electrons delocalization is not well understood. New computational evidences highlighting the accepted mechanism are proposed following a strategy coupling quantum theory of atoms in molecules and electron localization function topological analyses and enabling an extended quantification of donated/back-donated electrons fluxes along reaction paths going beyond the usual Dewar-Chatt-Duncanson model. Indeed, if the ligands coordination mode (phosphine, carbene) is commonly described as dative, it appears that ligands lone pairs stay centered on ligands as electrons are shared between metal and ligand with strong delocalization toward the latter. Overall, through strong trans effects coming from the carbon involved in the reductive elimination, palladium delocalizes its valence electrons not only toward phosphines but interestingly also toward the carbene. As back-donation increases during reductive elimination, one of the reaction key components is the palladium ligands ability to accept electrons. The rationalization of such electronic phenomena gives new directions for the design of palladium-catalyzed systems. PMID:25899703

  16. Bridging organometallics and quantum chemical topology: Understanding electronic relocalisation during palladium-catalyzed reductive elimination.

    PubMed

    de Courcy, Benoit; Derat, Etienne; Piquemal, Jean-Philip

    2015-06-01

    This article proposes to bridge two fields, namely organometallics and quantum chemical topology. To do so, Palladium-catalyzed reductive elimination is studied. Such reaction is a classical elementary step in organometallic chemistry, where the directionality of electrons delocalization is not well understood. New computational evidences highlighting the accepted mechanism are proposed following a strategy coupling quantum theory of atoms in molecules and electron localization function topological analyses and enabling an extended quantification of donated/back-donated electrons fluxes along reaction paths going beyond the usual Dewar-Chatt-Duncanson model. Indeed, if the ligands coordination mode (phosphine, carbene) is commonly described as dative, it appears that ligands lone pairs stay centered on ligands as electrons are shared between metal and ligand with strong delocalization toward the latter. Overall, through strong trans effects coming from the carbon involved in the reductive elimination, palladium delocalizes its valence electrons not only toward phosphines but interestingly also toward the carbene. As back-donation increases during reductive elimination, one of the reaction key components is the palladium ligands ability to accept electrons. The rationalization of such electronic phenomena gives new directions for the design of palladium-catalyzed systems.

  17. In situ observation of reduction kinetics and 2D mapping of chemical state for heterogeneous reduction in iron-ore sinters

    NASA Astrophysics Data System (ADS)

    Kimura, M.; Murao, R.; Ohta, N.; Noami, K.; Uemura, Y.; Niwa, Y.; Kimijima, K.; Takeichi, Y.; Nitani, H.

    2016-05-01

    Iron-ore sinters constitute the major component of the iron-bearing burden in blast furnaces, and the mechanism of their reduction is one of the key processes in iron making. The heterogeneous reduction of sintered oxides was investigated by the combination of X-ray fluorescence and absorption fine structure, X-ray diffraction, and computed tomography. Two - dimensional mapping of the chemical states (CSs) was performed. The iron CSs FeIII, FeII, and Fe0 exhibited a heterogeneous distribution in a reduced sinter. The reduction started near micro pores, at iron-oxide grains rather than calcium-ferrite ones. The heterogeneous reduction among grains in a sinter may cause the formation of micro cracks. These results provide fundamental insights into heterogeneous reduction schemes for iron-ore sinters.

  18. Dimensional reduction of the master equation for stochastic chemical networks: The reduced-multiplane method.

    PubMed

    Barzel, Baruch; Biham, Ofer; Kupferman, Raz; Lipshtat, Azi; Zait, Amir

    2010-08-01

    Chemical reaction networks which exhibit strong fluctuations are common in microscopic systems in which reactants appear in low copy numbers. The analysis of these networks requires stochastic methods, which come in two forms: direct integration of the master equation and Monte Carlo simulations. The master equation becomes infeasible for large networks because the number of equations increases exponentially with the number of reactive species. Monte Carlo methods, which are more efficient in integrating over the exponentially large phase space, also become impractical due to the large amounts of noisy data that need to be stored and analyzed. The recently introduced multiplane method [A. Lipshtat and O. Biham, Phys. Rev. Lett. 93, 170601 (2004)] is an efficient framework for the stochastic analysis of large reaction networks. It is a dimensional reduction method, based on the master equation, which provides a dramatic reduction in the number of equations without compromising the accuracy of the results. The reduction is achieved by breaking the network into a set of maximal fully connected subnetworks (maximal cliques). A separate master equation is written for the reduced probability distribution associated with each clique, with suitable coupling terms between them. This method is highly efficient in the case of sparse networks, in which the maximal cliques tend to be small. However, in dense networks some of the cliques may be rather large and the dimensional reduction is not as effective. Furthermore, the derivation of the multiplane equations from the master equation is tedious and difficult. Here we present the reduced-multiplane method in which the maximal cliques are broken down to the fundamental two-vertex cliques. The number of equations is further reduced, making the method highly efficient even for dense networks. Moreover, the equations take a simpler form, which can be easily constructed using a diagrammatic procedure, for any desired network

  19. Distinguishing solid bitumens formed by thermochemical sulfate reduction and thermal chemical alteration

    USGS Publications Warehouse

    Kelemen, S.R.; Walters, C.C.; Kwiatek, P.J.; Afeworki, M.; Sansone, M.; Freund, H.; Pottorf, R.J.; Machel, H.G.; Zhang, T.; Ellis, G.S.; Tang, Y.; Peters, K.E.

    2008-01-01

    Insoluble solid bitumens are organic residues that can form by the thermal chemical alteration (TCA) or thermochemical sulfate reduction (TSR) of migrated petroleum. TCA may actually encompass several low temperature processes, such as biodegradation and asphaltene precipitation, followed by thermal alteration. TSR is an abiotic redox reaction where petroleum is oxidized by sulfate. It is difficult to distinguish solid bitumens associated with TCA of petroleum from those associated with TSR when both processes occur at relatively high temperature. The focus of the present work was to characterize solid bitumen samples associated with TCA or TSR using X-ray photoelectron spectroscopy (XPS). XPS is a surface analysis conducted on either isolated or in situ (>25 ??m diameter) solid bitumen that can provide the relative abundance and chemical speciation of carbon, organic and inorganic heteroatoms (NSO). In this study, naturally occurring solid bitumens from three locations, Nisku Fm. Brazeau River area (TSR-related), LaBarge Field Madison Fm. (TSR-related), and the Alaskan Brooks range (TCA-related), are compared to organic solids generated during laboratory simulation of the TSR and TCA processes. The abundance and chemical nature of organic nitrogen and sulfur in solid bitumens can be understood in terms of the nature of (1) petroleum precursor molecules, (2) the concentration of nitrogen by way of thermal stress and (3) the mode of sulfur incorporation. TCA solid bitumens originate from polar materials that are initially rich in sulfur and nitrogen. Aromaticity and nitrogen increase as thermal stress cleaves aliphatic moieties and condensation reactions take place. Organic sulfur in TCA organic solids remains fairly constant with increasing maturation (3.5 to ???17 sulfur per 100 carbons) into aromatic structures and to the low levels of nitrogen in their hydrocarbon precursors. Hence, XPS results provide organic chemical composition information that helps to

  20. Synthesis of Cu core Ag shell nanoparticles using chemical reduction method

    NASA Astrophysics Data System (ADS)

    Chinh Trinh, Dung; Dung Dang, Thi My; Khanh Huynh, Kim; Fribourg-Blanc, Eric; Chien Dang, Mau

    2015-01-01

    A simple chemical reduction method is used to prepare colloidal bimetallic Cu-Ag core-shell (Cu@Ag) nanoparticles. Polyvinyl pyrrolidone (PVP) was used as capping agent, and ascorbic acid (C6H8O6) and sodium borohydride (NaBH4) were used as reducing agents. The obtained Cu@Ag nanoparticles were characterized by powder x-ray diffraction (XRD), transmission electron microscopy (TEM) and UV-vis spectrophotometry. The influence of [Ag]/[Cu] molar ratios on the formation of Ag coatings on the Cu particles was investigated. From the TEM results we found that the ratio [Ag+]/[Cu2+] = 0.2 is the best for the stability of Cu@Ag nanoparticles with an average size of 22 nm. It is also found out that adding ammonium hydroxide (NH4OH) makes the obtained Cu@Ag nanoparticles more stable over time when pure deionized water is used as solvent.

  1. Dissociative electron transfer in polychlorinated aromatics. Reduction potentials from convolution analysis and quantum chemical calculations.

    PubMed

    Romańczyk, Piotr P; Rotko, Grzegorz; Kurek, Stefan S

    2016-08-10

    Formal potentials of the first reduction leading to dechlorination in dimethylformamide were obtained from convolution analysis of voltammetric data and confirmed by quantum chemical calculations for a series of polychlorinated benzenes: hexachlorobenzene (-2.02 V vs. Fc(+)/Fc), pentachloroanisole (-2.14 V), and 2,4-dichlorophenoxy- and 2,4,5-trichlorophenoxyacetic acids (-2.35 V and -2.34 V, respectively). The key parameters required to calculate the reduction potential, electron affinity and/or C-Cl bond dissociation energy, were computed at both DFT-D and CCSD(T)-F12 levels. Comparison of the obtained gas-phase energies and redox potentials with experiment enabled us to verify the relative energetics and the performance of various implicit solvent models. Good agreement with the experiment was achieved for redox potentials computed at the DFT-D level, but only for the stepwise mechanism owing to the error compensation. For the concerted electron transfer/C-Cl bond cleavage process, the application of a high level coupled cluster method is required. Quantum chemical calculations have also demonstrated the significant role of the π*ring and σ*C-Cl orbital mixing. It brings about the stabilisation of the non-planar, C2v-symmetric C6Cl6˙(-) radical anion, explains the experimentally observed low energy barrier and the transfer coefficient close to 0.5 for C6Cl5OCH3 in an electron transfer process followed by immediate C-Cl bond cleavage in solution, and an increase in the probability of dechlorination of di- and trichlorophenoxyacetic acids due to substantial population of the vibrational excited states corresponding to the out-of-plane C-Cl bending at ambient temperatures.

  2. Dissociative electron transfer in polychlorinated aromatics. Reduction potentials from convolution analysis and quantum chemical calculations.

    PubMed

    Romańczyk, Piotr P; Rotko, Grzegorz; Kurek, Stefan S

    2016-08-10

    Formal potentials of the first reduction leading to dechlorination in dimethylformamide were obtained from convolution analysis of voltammetric data and confirmed by quantum chemical calculations for a series of polychlorinated benzenes: hexachlorobenzene (-2.02 V vs. Fc(+)/Fc), pentachloroanisole (-2.14 V), and 2,4-dichlorophenoxy- and 2,4,5-trichlorophenoxyacetic acids (-2.35 V and -2.34 V, respectively). The key parameters required to calculate the reduction potential, electron affinity and/or C-Cl bond dissociation energy, were computed at both DFT-D and CCSD(T)-F12 levels. Comparison of the obtained gas-phase energies and redox potentials with experiment enabled us to verify the relative energetics and the performance of various implicit solvent models. Good agreement with the experiment was achieved for redox potentials computed at the DFT-D level, but only for the stepwise mechanism owing to the error compensation. For the concerted electron transfer/C-Cl bond cleavage process, the application of a high level coupled cluster method is required. Quantum chemical calculations have also demonstrated the significant role of the π*ring and σ*C-Cl orbital mixing. It brings about the stabilisation of the non-planar, C2v-symmetric C6Cl6˙(-) radical anion, explains the experimentally observed low energy barrier and the transfer coefficient close to 0.5 for C6Cl5OCH3 in an electron transfer process followed by immediate C-Cl bond cleavage in solution, and an increase in the probability of dechlorination of di- and trichlorophenoxyacetic acids due to substantial population of the vibrational excited states corresponding to the out-of-plane C-Cl bending at ambient temperatures. PMID:27477334

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

    NASA Astrophysics Data System (ADS)

    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.

  4. Uranium and thorium hydride complexes as multielectron reductants: a combined neutron diffraction and quantum chemical study.

    PubMed

    Grant, Daniel J; Stewart, Timothy J; Bau, Robert; Miller, Kevin A; Mason, Sax A; Gutmann, Matthias; McIntyre, Garry J; Gagliardi, Laura; Evans, William J

    2012-03-19

    The unusual uranium reaction system in which uranium(4+) and uranium(3+) hydrides interconvert by formal bimetallic reductive elimination and oxidative addition reactions, [(C(5)Me(5))(2)UH(2)](2) (1) ⇌ [(C(5)Me(5))(2)UH](2) (2) + H(2), was studied by employing multiconfigurational quantum chemical and density functional theory methods. 1 can act as a formal four-electron reductant, releasing H(2) gas as the byproduct of four H(2)/H(-) redox couples. The calculated structures for both reactants and products are in good agreement with the X-ray diffraction data on 2 and 1 and the neutron diffraction data on 1 obtained under H(2) pressure as part of this study. The interconversion of the uranium(4+) and uranium(3+) hydride species was calculated to be near thermoneutral (~-2 kcal/mol). Comparison with the unknown thorium analogue, [(C(5)Me(5))(2)ThH](2), shows that the thorium(4+) to thorium(3+) hydride interconversion reaction is endothermic by 26 kcal/mol.

  5. pH effect on the aggregation of silver nanoparticles synthesized by chemical reduction

    NASA Astrophysics Data System (ADS)

    Alqadi, M. K.; Abo Noqtah, O. A.; Alzoubi, F. Y.; Alzouby, J.; Aljarrah, K.

    2014-01-01

    Silver colloidal nanoparticles were prepared according to the chemical reduction method in which the ascorbic acid was used as a reducing agent and sodium citrate as a stabilizing agent. The absorption spectra of all prepared samples obtained using the UV-Vis spectrophotometer showed a surface plasmon peak at a wavelength of about 420 nm. The size of the silver nanoparticles was controlled by changing the pH values of the reaction system. At high pH, smaller size silver nanoparticles were obtained compared to low pH values. This difference can be attributed to the difference in the reduction rate of the precursor. In addition to the inverse proportionality between the size and the pH value it is clear that increasing the pH value enables us to obtain spherical nanoparticles while at low pH, rods and triangular particle shapes were formed. Poor balance between nucleation and growth processes could be the cause of this result.

  6. Synthesis and characterization of silver/talc nanocomposites using the wet chemical reduction method.

    PubMed

    Shameli, Kamyar; Ahmad, Mansor Bin; Yunus, Wan Zin Wan; Ibrahim, Nor Azowa; Darroudi, Majid

    2010-10-05

    In this study, silver nanoparticles (Ag-NPs) were synthesized using the wet chemical reduction method on the external surface layer of talc mineral as a solid support. Silver nitrate and sodium borohydride were used as the silver precursor and reducing agent in talc. The talc was suspended in aqueous AgNO(3) solution. After the absorption of Ag(+) on the surface, the ions were reduced with NaBH(4). The interlamellar space limits were without many changes (d(s) = 9.34-9.19 A(º)); therefore, Ag-NPs formed on the exterior surface of talc, with d(ave) = 7.60-13.11 nm in diameter. The properties of Ag/talc nanocomposites (Ag/talc-NCs) and the diameters of the Ag-NPs prepared in this way depended on the primary AgNO(3) concentration. The prepared Ag-NPs were characterized by ultraviolet-visible spectroscopy, powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and Fourier transform infrared. These Ag/talc-NCs may have potential applications in the chemical and biological industries.

  7. Chemical noise reduction via mass spectrometry and ion/ion charge inversion: amino acids.

    PubMed

    Hassell, Kerry M; LeBlanc, Yves C; McLuckey, Scott A

    2011-05-01

    Charge inversion ion/ion reactions can provide a significant reduction in chemical noise associated with mass spectra derived from complex mixtures for species composed of both acidic and basic sites, provided the ions derived from the matrix largely undergo neutralization. Amino acids constitute an important class of amphoteric compounds that undergo relatively efficient charge inversion. Precipitated plasma constitutes a relatively complex biological matrix that yields detectable signals at essentially every mass-to-charge value over a wide range. This chemical noise can be dramatically reduced using multiply charged reagent ions that can invert the charge of species amenable to the transfer of multiple charges upon a single interaction and by detecting product ions of opposite polarity. The principle is illustrated here with amino acids present in precipitated plasma subjected to ionization in the positive mode, reaction with anions derived from negative nanoelectrospray ionization of poly (amido amine) dendrimer generation 3.5, and mass analysis in the negative ion mode. PMID:21456599

  8. Microwave enhanced chemical reduction process for nitrite-containing wastewater treatment using sulfaminic acid.

    PubMed

    Li, Nan; Wang, Peng; Liu, Qingsong; Cao, Hailei

    2010-01-01

    High-concentration nitrite-containing wastewater that presents extreme toxicity to human health and organisms is difficult to be treated using traditional biological process. In this study, a novel microwave-enhanced chemical reduction process (MECRP) using sulfaminic acid (SA) was proposed as a new manner to treat such type of wastewater. Based on lab-scale experiments, it was shown that 75%-80% nitrite (NO2-) could be removed within time as short as 4 min under 50 W microwave irradiation in pH range 5-10 when molar ratio of SA to nitrite (SA/NO2-) was 0.8. Pilot-scale investigations demonstrated that MECRP was able to achieve nitrite and chemical oxygen demand (COD) removal with efficiency up to 80% and 20%, respectively under operating conditions of SA concentration 80 kg/m3, SA/NO2- ratio 0.8, microwave power 3.4 kW, and stirring time 3 min. Five-day biological oxygen demand (BOD5)/COD value of treated effluent after MECRP was increased from 0.05 to 0.36 (by 620%), which clearly suggested a considerable improvement of biodegradability for subsequent biological treatment. This study provided a demonstration of using microwave irradiation to enhance reaction between SA and nitrite in a short time, in which nitrite in wastewater was completely converted into nitrogen gas without leaving any sludge and secondary pollutants. PMID:20397387

  9. Dimensional reduction of the master equation for stochastic chemical networks: The reduced-multiplane method

    NASA Astrophysics Data System (ADS)

    Barzel, Baruch; Biham, Ofer; Kupferman, Raz; Lipshtat, Azi; Zait, Amir

    2010-08-01

    Chemical reaction networks which exhibit strong fluctuations are common in microscopic systems in which reactants appear in low copy numbers. The analysis of these networks requires stochastic methods, which come in two forms: direct integration of the master equation and Monte Carlo simulations. The master equation becomes infeasible for large networks because the number of equations increases exponentially with the number of reactive species. Monte Carlo methods, which are more efficient in integrating over the exponentially large phase space, also become impractical due to the large amounts of noisy data that need to be stored and analyzed. The recently introduced multiplane method [A. Lipshtat and O. Biham, Phys. Rev. Lett. 93, 170601 (2004)10.1103/PhysRevLett.93.170601] is an efficient framework for the stochastic analysis of large reaction networks. It is a dimensional reduction method, based on the master equation, which provides a dramatic reduction in the number of equations without compromising the accuracy of the results. The reduction is achieved by breaking the network into a set of maximal fully connected subnetworks (maximal cliques). A separate master equation is written for the reduced probability distribution associated with each clique, with suitable coupling terms between them. This method is highly efficient in the case of sparse networks, in which the maximal cliques tend to be small. However, in dense networks some of the cliques may be rather large and the dimensional reduction is not as effective. Furthermore, the derivation of the multiplane equations from the master equation is tedious and difficult. Here we present the reduced-multiplane method in which the maximal cliques are broken down to the fundamental two-vertex cliques. The number of equations is further reduced, making the method highly efficient even for dense networks. Moreover, the equations take a simpler form, which can be easily constructed using a diagrammatic procedure

  10. The invariant constrained equilibrium edge preimage curve method for the dimension reduction of chemical kinetics

    NASA Astrophysics Data System (ADS)

    Ren, Zhuyin; Pope, Stephen B.; Vladimirsky, Alexander; Guckenheimer, John M.

    2006-03-01

    This work addresses the construction and use of low-dimensional invariant manifolds to simplify complex chemical kinetics. Typically, chemical kinetic systems have a wide range of time scales. As a consequence, reaction trajectories rapidly approach a hierarchy of attracting manifolds of decreasing dimension in the full composition space. In previous research, several different methods have been proposed to identify these low-dimensional attracting manifolds. Here we propose a new method based on an invariant constrained equilibrium edge (ICE) manifold. This manifold (of dimension nr) is generated by the reaction trajectories emanating from its (nr-1)-dimensional edge, on which the composition is in a constrained equilibrium state. A reasonable choice of the nr represented variables (e.g., nr "major" species) ensures that there exists a unique point on the ICE manifold corresponding to each realizable value of the represented variables. The process of identifying this point is referred to as species reconstruction. A second contribution of this work is a local method of species reconstruction, called ICE-PIC, which is based on the ICE manifold and uses preimage curves (PICs). The ICE-PIC method is local in the sense that species reconstruction can be performed without generating the whole of the manifold (or a significant portion thereof). The ICE-PIC method is the first approach that locally determines points on a low-dimensional invariant manifold, and its application to high-dimensional chemical systems is straightforward. The "inputs" to the method are the detailed kinetic mechanism and the chosen reduced representation (e.g., some major species). The ICE-PIC method is illustrated and demonstrated using an idealized H2/O system with six chemical species. It is then tested and compared to three other dimension-reduction methods for the test case of a one-dimensional premixed laminar flame of stoichiometric hydrogen/air, which is described by a detailed mechanism

  11. Reduction of hexavalent chromium by fasted and fed human gastric fluid. I. Chemical reduction and mitigation of mutagenicity.

    PubMed

    De Flora, Silvio; Camoirano, Anna; Micale, Rosanna T; La Maestra, Sebastiano; Savarino, Vincenzo; Zentilin, Patrizia; Marabotto, Elisa; Suh, Mina; Proctor, Deborah M

    2016-09-01

    Evaluation of the reducing capacity of human gastric fluid from healthy individuals, under fasted and fed conditions, is critical for assessing the cancer hazard posed by ingested hexavalent chromium [Cr(VI)] and for developing quantitative physiologically-based pharmacokinetic models used in risk assessment. In the present study, the patterns of Cr(VI) reduction were evaluated in 16 paired pre- and post-meal gastric fluid samples collected from 8 healthy volunteers. Human gastric fluid was effective both in reducing Cr(VI), as measured by using the s-diphenylcarbazide colorimetric method, and in attenuating mutagenicity in the Ames test. The mean (±SE) Cr(VI)-reducing ability of post-meal samples (20.4±2.6μgCr(VI)/mL gastric fluid) was significantly higher than that of pre-meal samples (10.2±2.3μgCr(VI)/mL gastric fluid). When using the mutagenicity assay, the decrease of mutagenicity produced by pre-meal and post-meal samples corresponded to reduction of 13.3±1.9 and 25.6±2.8μgCr(VI)/mL gastric fluid, respectively. These data are comparable to parallel results conducted by using speciated isotope dilution mass spectrometry. Cr(VI) reduction was rapid, with >70% of total reduction occurring within 1min and 98% of reduction is achieved within 30min with post-meal gastric fluid at pH2.0. pH dependence was observed with decreasing Cr(VI) reducing capacity at higher pH. Attenuation of the mutagenic response is consistent with the lack of DNA damage observed in the gastrointestinal tract of rodents following administration of ≤180ppm Cr(VI) for up to 90days in drinking water. Quantifying Cr(VI) reduction kinetics in the human gastrointestinal tract is necessary for assessing the potential hazards posed by Cr(VI) in drinking water. PMID:27404458

  12. Flow Alteration and Chemical Reduction: Air Stripping to Lessen Subsurface Discharges of Mercury to Surface Water

    NASA Astrophysics Data System (ADS)

    Brooks, S. C.; Bogle, M.; Liang, L.; Miller, C. L.; Peterson, M.; Southworth, G. R.; Spalding, B. P.

    2009-12-01

    process water. Greater than 90% of the mercury in that discharge was converted to the highly volatile dissolved Hg(0) by dechlorinating the streamflow with ascorbic acid and then treating it with a near stoichiometric concentration of the chemical reductant stannous chloride. Preliminary engineering evaluations indicate that once converted to Hg(0), mercury in the stream discharge could be removed by in-situ air stripping at the discharge point or perhaps within the enclosed stormdrain network upstream. If chemical reduction:air stripping was eventualy able to remove 80% or more of Hg from water, input to the stream from that source could be lowered from 6 - 8 g/d to 1 - 2 g/d. Together, these two strategies have the potential to eliminate much of the remaining dissolved Hg input to the creek.

  13. Simultaneous nitrate reduction and acetaminophen oxidation using the continuous-flow chemical-less VUV process as an integrated advanced oxidation and reduction process.

    PubMed

    Moussavi, Gholamreza; Shekoohiyan, Sakine

    2016-11-15

    This work was aimed at investigating the performance of the continuous-flow VUV photoreactor as a novel chemical-less advanced process for simultaneously oxidizing acetaminophen (ACT) as a model of pharmaceuticals and reducing nitrate in a single reactor. Solution pH was an important parameter affecting the performance of VUV; the highest ACT oxidation and nitrate reduction attained at solution pH between 6 and 8. The ACT was oxidized mainly by HO while the aqueous electrons were the main working agents in the reduction of nitrate. The performance of VUV photoreactor improved with the increase of hydraulic retention time (HRT); the complete degradation of ACT and ∼99% reduction of nitrate with 100% N2 selectivity achieved at HRT of 80min. The VUV effluent concentrations of nitrite and ammonium at HRT of 80min were below the drinking water standards. The real water sample contaminated with the ACT and nitrate was efficiently treated in the VUV photoreactor. Therefore, the VUV photoreactor is a chemical-less advanced process in which both advanced oxidation and advanced reduction reactions are accomplished. This unique feature possesses VUV photoreactor as a promising method of treating water contaminated with both pharmaceutical and nitrate. PMID:27434736

  14. Simultaneous nitrate reduction and acetaminophen oxidation using the continuous-flow chemical-less VUV process as an integrated advanced oxidation and reduction process.

    PubMed

    Moussavi, Gholamreza; Shekoohiyan, Sakine

    2016-11-15

    This work was aimed at investigating the performance of the continuous-flow VUV photoreactor as a novel chemical-less advanced process for simultaneously oxidizing acetaminophen (ACT) as a model of pharmaceuticals and reducing nitrate in a single reactor. Solution pH was an important parameter affecting the performance of VUV; the highest ACT oxidation and nitrate reduction attained at solution pH between 6 and 8. The ACT was oxidized mainly by HO while the aqueous electrons were the main working agents in the reduction of nitrate. The performance of VUV photoreactor improved with the increase of hydraulic retention time (HRT); the complete degradation of ACT and ∼99% reduction of nitrate with 100% N2 selectivity achieved at HRT of 80min. The VUV effluent concentrations of nitrite and ammonium at HRT of 80min were below the drinking water standards. The real water sample contaminated with the ACT and nitrate was efficiently treated in the VUV photoreactor. Therefore, the VUV photoreactor is a chemical-less advanced process in which both advanced oxidation and advanced reduction reactions are accomplished. This unique feature possesses VUV photoreactor as a promising method of treating water contaminated with both pharmaceutical and nitrate.

  15. Deposition of silver nanoparticles on multiwalled carbon nanotubes by chemical reduction process and their antimicrobial effects

    NASA Astrophysics Data System (ADS)

    Haider, Adawiya J.; Thamir, Amin D.; Ahmed, Duha S.; Mohammad, M. R.

    2016-07-01

    In this paper, the functionalization of raw-MWCNTs involves oxidation reaction using concentrated acid mixture of HNO3:H2SO4 (1:3), via ultrasonic bath (170 W, 50 kHz) to obtain functional groups. Then Ag nanoparticles are decorated the outside over the surface of functionalized MWCNTs using a chemical reduction process resulting in the formation of(Ag/ MWCNTs) hybrid material. The results showed that outer diameter functionalized F-MWCNTs andAg nanoparticles size was about (11-80) nm and (10 to 25) nm, respectively using TEM and HRTEM. The crystallographic structure of MWCNTs using X-ray diffraction (XRD) analysis proved diffraction peaks at 38.1°, 44.3°, 64.7° and 77.4° degrees namely, Ag (111), Ag (200), Ag (220), and Ag (311) of the face-centered cubic lattice of Ag, respectively, excepting the peak at 2θ =25.6°, which correspond to the (0 0 2) reflection of the MWNTs are corresponding to Ag/MWNTs. The antimicrobial activities of Ag/MWCNTs hybrid using plate count method showed that decreasing a large number of bacteria colonies of E. coli and S. aureu with increasing the hybrid concentrations after incubation for 24h in shaker incubator with percentage of inhibition approaching 100%.

  16. Magnetite Fe3O4 nanoparticles synthesis by wet chemical reduction and their characterization

    NASA Astrophysics Data System (ADS)

    Chaki, S. H.; Malek, Tasmira J.; Chaudhary, M. D.; Tailor, J. P.; Deshpande, M. P.

    2015-09-01

    The authors report the synthesis of Fe3O4 nanoparticles by wet chemical reduction technique at ambient temperature and its characterization. Ferric chloride hexa-hydrate (FeCl3 · 6H2O) and sodium boro-hydrate (NaBH4) were used for synthesis of Fe3O4 nanoparticles at ambient temperature. The elemental composition of the synthesized Fe3O4 nanoparticles was determined by energy dispersive analysis of x-rays technique. The x-ray diffraction (XRD) technique was used for structural characterization of the nanoparticles. The crystallite size of the nanoparticles was determined using XRD data employing Scherrer’s formula and Hall-Williamson’s plot. Surface morphology of as-synthesized Fe3O4 nanoparticles was studied by scanning electron microscopy. High resolution transmission electron microscopy analysis of the as-synthesized Fe3O4 nanoparticles showed narrow range of particles size distribution. The optical absorption of the synthesized Fe3O4 nanoparticles was studied by UV-vis-NIR spectroscopy. The as-synthesized nanoparticles were analyzed by Fourier transform infrared spectroscopy technique for absorption band study in the infrared region. The magnetic properties of the as-synthesized Fe3O4 nanoparticles were evaluated by vibrating sample magnetometer technique. The thermal stability of the as-synthesized Fe3O4 nanoparticles was studied by thermogravimetric technique. The obtained results are elaborated and discussed in details in this paper.

  17. Chemical evaluation of odor reduction by soil injection of animal manure.

    PubMed

    Feilberg Tavs Nyord, Anders; Hansen, Martin Nørregaard; Lindholst, Sabine

    2011-01-01

    Field application of animal manure is a major cause of odor nuisance in the local environment. Therefore, there is a need for methods for measuring the effect of technologies for reducing odor after manure application. In this work, chemical methods were used to identify key odorants from field application of pig manure based on experiments with surface application by trailing hoses and soil injection. Results from three consecutive years of field trials with full-scale equipment are reported. Methods applied were: membrane inlet mass spectrometry (MIMS), proton-transfer-reaction mass spectrometry (PTR-MS), gold-film hydrogen sulfide (H₂S) detection, all performed on site, and thermal desorption gas chromatography with mass spectrometry (TD-GC/MS) based on laboratory analyses of field samples. Samples were collected from a static flux chamber often used for obtaining samples for dynamic olfactometry. While all methods were capable of detecting relevant odorants, PTR-MS gave the most comprehensive results. Based on odor threshold values, 4-methylphenol, H₂S, and methanethiol are suggested as key odorants. Significant odorant reductions by soil injection were consistently observed in all trials. The flux chamber technique was demonstrated to be associated with critical errors due to compound instabilities in the chamber. This was most apparent for H₂S, on a time scale of a few minutes, and on a longer time scale for methanethiol.

  18. SITE PROGRAM DEMONSTRATION ECO LOGIC INTERNATIONAL GAS-PHASE CHEMICAL REDUCTION PROCESS, BAY CITY, MICHIGAN TECHNOLOGY EVALUATION REPORT

    EPA Science Inventory

    The SITE Program funded a field demonstration to evaluate the Eco Logic Gas-Phase Chemical Reduction Process developed by ELI Eco Logic International Inc. (ELI), Ontario, Canada. The Demonstration took place at the Middleground Landfill in Bay City, Michigan using landfill wa...

  19. TRACI THE TOOL FOR THE REDUCTION AND ASSESSMENT OF CHEMICAL AND OTHER ENVIRONMENTAL IMPACTS - VERSION 2 CHANGES

    EPA Science Inventory

    The Tool for the Reduction and Assessment of Chemical and other environmental Impacts (TRACI) was developed to allow the quantification of environmental impacts for a variety of impact categories which are necessary for a comprehensive impact assessment. See Figure 1. TRACI is c...

  20. TRACI 2.0 - The Tool for the Reduction and Assessment of Chemical and other environmental Impacts

    EPA Science Inventory

    TRACI 2.0, the Tool for the Reduction and Assessment of Chemical and other environmental Impacts 2.0, has been expanded and developed for sustainability metrics, life cycle impact assessment, industrial ecology, and process design impact assessment for developing increasingly sus...

  1. Estimating the One-Electron Reduction Potential for Vanadium (V) by Chemical Techniques: An Experiment for General Chemistry.

    ERIC Educational Resources Information Center

    Wentworth, R. A. D.

    1985-01-01

    Describes an experiment which requires only qualitative observations, is suitable for general chemistry students, prompts an understanding of thermodynamic spontaneity, gives chemical meaning to electrode potentials, requires non-electrochemical equipment, and allows estimates of the standard potential for the reduction of Vanadium (V) to V (IV).…

  2. The effect of chemical treatment on reduction of aflatoxins and ochratoxin A in black and white pepper during washing.

    PubMed

    Jalili, M; Jinap, S; Son, R

    2011-04-01

    The effect of 18 different chemicals, which included acidic compounds (sulfuric acid, chloridric acid, phosphoric acid, benzoic acid, citric acid, acetic acid), alkaline compounds (ammonia, sodium bicarbonate, sodium hydroxide, potassium hydroxide, calcium hydroxide), salts (acetate ammonium, sodium bisulfite, sodium hydrosulfite, sodium chloride, sodium sulfate) and oxidising agents (hydrogen peroxide, sodium hypochlorite), on the reduction of aflatoxins B(1), B(2), G(1) and G(2) and ochratoxin A (OTA) was investigated in black and white pepper. OTA and aflatoxins were determined using HPLC after immunoaffinity column clean-up. Almost all of the applied chemicals showed a significant degree of reduction on mycotoxins (p < 0.05). The lowest and highest reduction of aflatoxin B(1), which is the most dangerous aflatoxin, was 20.5% ± 2.7% using benzoic acid and 54.5% ± 2.7% using sodium hydroxide. There was no significant difference between black and white peppers (p < 0.05). PMID:21416415

  3. Photochemical modeling in California with two chemical mechanisms: model intercomparison and response to emission reductions.

    PubMed

    Cai, Chenxia; Kelly, James T; Avise, Jeremy C; Kaduwela, Ajith P; Stockwell, William R

    2011-05-01

    An updated version of the Statewide Air Pollution Research Center (SAPRC) chemical mechanism (SAPRC07C) was implemented into the Community Multiscale Air Quality (CMAQ) version 4.6. CMAQ simulations using SAPRC07C and the previously released version, SAPRC99, were performed and compared for an episode during July-August, 2000. Ozone (O3) predictions of the SAPRC07C simulation are generally lower than those of the SAPRC99 simulation in the key areas of central and southern California, especially in areas where modeled concentrations are greater than the federal 8-hr O3 standard of 75 parts per billion (ppb) and/or when the volatile organic compound (VOC)/nitrogen oxides (NOx) ratio is less than 13. The relative changes of ozone production efficiency (OPE) against the VOC/NOx ratio at 46 sites indicate that the OPE is reduced in SAPRC07C compared with SAPRC99 at most sites by as much as approximately 22%. The SAPRC99 and SAPRC07C mechanisms respond similarly to 20% reductions in anthropogenic VOC emissions. The response of the mechanisms to 20% NOx emissions reductions can be grouped into three cases. In case 1, in which both mechanisms show a decrease in daily maximum 8-hr O3 concentration with decreasing NOx emissions, the O3 decrease in SAPRC07C is smaller. In case 2, in which both mechanisms show an increase in O3 with decreasing NOx emissions, the O3 increase is larger in SAPRC07C. In case 3, SAPRC07C simulates an increase in O3 in response to reduced NOx emissions whereas SAPRC99 simulates a decrease in O3 for the same region. As a result, the areas where NOx controls would be disbeneficial are spatially expanded in SAPRC07C. Although the results presented here are valuable for understanding differences in predictions and model response for SAPRC99 and SAPRC07C, the study did not evaluate the impact of mechanism differences in the context of the U.S. Environmental Protection Agency's guidance for using numerical models in demonstrating air quality attainment

  4. Photochemical modeling in California with two chemical mechanisms: model intercomparison and response to emission reductions.

    PubMed

    Cai, Chenxia; Kelly, James T; Avise, Jeremy C; Kaduwela, Ajith P; Stockwell, William R

    2011-05-01

    An updated version of the Statewide Air Pollution Research Center (SAPRC) chemical mechanism (SAPRC07C) was implemented into the Community Multiscale Air Quality (CMAQ) version 4.6. CMAQ simulations using SAPRC07C and the previously released version, SAPRC99, were performed and compared for an episode during July-August, 2000. Ozone (O3) predictions of the SAPRC07C simulation are generally lower than those of the SAPRC99 simulation in the key areas of central and southern California, especially in areas where modeled concentrations are greater than the federal 8-hr O3 standard of 75 parts per billion (ppb) and/or when the volatile organic compound (VOC)/nitrogen oxides (NOx) ratio is less than 13. The relative changes of ozone production efficiency (OPE) against the VOC/NOx ratio at 46 sites indicate that the OPE is reduced in SAPRC07C compared with SAPRC99 at most sites by as much as approximately 22%. The SAPRC99 and SAPRC07C mechanisms respond similarly to 20% reductions in anthropogenic VOC emissions. The response of the mechanisms to 20% NOx emissions reductions can be grouped into three cases. In case 1, in which both mechanisms show a decrease in daily maximum 8-hr O3 concentration with decreasing NOx emissions, the O3 decrease in SAPRC07C is smaller. In case 2, in which both mechanisms show an increase in O3 with decreasing NOx emissions, the O3 increase is larger in SAPRC07C. In case 3, SAPRC07C simulates an increase in O3 in response to reduced NOx emissions whereas SAPRC99 simulates a decrease in O3 for the same region. As a result, the areas where NOx controls would be disbeneficial are spatially expanded in SAPRC07C. Although the results presented here are valuable for understanding differences in predictions and model response for SAPRC99 and SAPRC07C, the study did not evaluate the impact of mechanism differences in the context of the U.S. Environmental Protection Agency's guidance for using numerical models in demonstrating air quality attainment

  5. Model reduction and temperature uniformity control for rapid thermal chemical vapor deposition reactors

    NASA Astrophysics Data System (ADS)

    Theodoropoulou, Artemis-Georgia

    The consideration of Rapid Thermal Processing (RTP) in semiconductor manufacturing has recently been increasing. As a result, control of RTP systems has become of great importance since it is expected to help in addressing uniformity problems that, so far, have been obstructing the acceptance of the method. The spatial distribution appearing in RTP models necessitates the use of model reduction in order to obtain models of a size suitable for use in control algorithms. This dissertation addresses model reduction as well as control issues for RTP systems. A model of a three-zone Rapid Thermal Chemical Vapor Deposition (RTCVD) system is developed to study the effects of spatial wafer temperature patterns on polysilicon deposition uniformity. A sequence of simulated runs is performed, varying the lamp power profiles so that different wafer temperature modes are excited. The dominant spatial wafer thermal modes are extracted via Proper Orthogonal Decomposition and subsequently used as a set of trial functions to represent both the wafer temperature and deposition thickness. A collocation formulation of Galerkin's method is used to discretize the original modeling equations, giving a low-order model which loses little of the original, high-order model's fidelity. We make use of the excellent predictive capabilities of the reduced model to optimize power inputs to the lamp banks to achieve a desired polysilicon deposition thickness at the end of a run with minimal deposition spatial nonuniformity. Since the results illustrate that the optimization procedure benefits from the use of the reduced-order model, we further utilize the reduced order model for real time Model Based Control. The feedback controller is designed using the Internal Model Control (IMC) structure especially modified to handle systems described by ordinary differential and algebraic equations. The IMC controller is obtained using optimal control theory on singular arcs extended for multi input systems

  6. Direct chemical reduction of neptunium oxide to neptunium metal using calcium and calcium chloride

    NASA Astrophysics Data System (ADS)

    Squires, Leah N.; Lessing, Paul

    2016-04-01

    A process of direct reduction of neptunium oxide to neptunium metal using calcium metal as the reducing agent is discussed. After reduction of the oxide to metal, the metal is separated by density from the other components of the reaction mixture and can be easily removed upon cooling. The direct reduction technique consistently produces high purity (98%-99% pure) neptunium metal.

  7. Characterization of solid bitumens originating from thermal chemical alteration and thermochemical sulfate reduction

    NASA Astrophysics Data System (ADS)

    Kelemen, Simon R.; Walters, Clifford C.; Kwiatek, Peter J.; Freund, Howard; Afeworki, Mobae; Sansone, Michael; Lamberti, William A.; Pottorf, Robert J.; Machel, Hans G.; Peters, Kenneth E.; Bolin, Trudy

    2010-09-01

    Solid bitumen can arise from several reservoir processes acting on migrated petroleum. Insoluble solid organic residues can form by oxidative processes associated with thermochemical sulfate reduction (TSR) as well as by thermal chemical alteration (TCA) of petroleum. TCA may follow non-thermal processes, such as biodegradation and asphaltene precipitation, that produce viscous fluids enriched in polar compounds that are then altered into solid bitumens. It is difficult to distinguish solid bitumen formed by TCA from TSR since both processes occur under relatively high temperatures. The focus of the present work is to characterize solid bitumen samples associated with TSR- or TCA-processes using a combination of solid-state X-ray Photoelectron Spectroscopy (XPS), Sulfur X-ray Absorption Near Edge Structure Spectroscopy (S-XANES), and 13C NMR. Naturally occurring solid bitumens from three locations, Nisku Formation, Brazeau River area (TSR-related); La Barge Field, Madison Formation (TSR-related); and, the Alaskan North Slope, Brooks Range (TCA-related), are compared to solid bitumens generated in laboratory simulations of TSR and TCA. The chemical nature of solid bitumens with respect to organic nitrogen and sulfur can be understood in terms of (1) the nature of hydrocarbon precursor molecules, (2) the mode of sulfur incorporation, and (3) their concentration during thermal stress. TSR-solid bitumen is highly aromatic, sulfur-rich, and nitrogen-poor. These heteroatom distributions are attributed to the ability of TSR to incorporate copious amounts of inorganic sulfur (S/C atomic ratio >0.035) into aromatic structures and to initial low levels of nitrogen in the unaltered petroleum. In contrast, TCA-solid bitumen is derived from polar materials that are initially rich in sulfur and nitrogen. Aromaticity and nitrogen increase as thermal stress cleaves aliphatic moieties and condensation reactions take place. TCA-bitumens from the Brooks Range have <75% aromatic

  8. Chemical Kinetic and Molecular Genetic Study of Selenium Oxyanion Reduction by Enterobactor cloacae SLD1a-1

    SciTech Connect

    Ma,J.; Kobayashi, D.; Yee, N.

    2007-01-01

    Microbial processes play an important role in the redox transformations of toxic selenium oxyanions. In this study, we employed chemical kinetic and molecular genetic techniques to investigate the mechanisms of Se(IV) and Se(VI) reduction by the facultative anaerobe Enterobacter cloacae SLD1a-1. The rates of microbial selenium oxyanion reduction were measured as a function of initial selenium oxyanion concentration (0-1.0 mM) and temperature (10-40 C), and mutagenesis studies were performed to identify the genes involved in the selenium oxyanion reduction pathway. The results indicate that Se(IV) reduction is significantly more rapid than the reduction of Se(VI). The kinetics of the reduction reactions were successfully quantified using the Michaelis-Menten kinetic equation. Both the rates of Se(VI) and Se(IV) reduction displayed strong temperature-dependence with Ea values of 121 and 71.2 kJ/mol, respectively. X-ray absorption near-edge spectra collected for the precipitates formed by Se(VI) and Se(IV) reduction confirmed the formation of Se(0). A miniTn5 transposon mutant of E. cloacae SLD1a-1 was isolated that had lost the ability to reduce Se(VI) but was not affected in Se(IV) reduction activity. Nucleotide sequence analysis revealed the transposon was inserted within a tatC gene, which encodes for a central protein in the twin arginine translocation system. Complementation by the wild-type tatC sequence restored the ability of mutant strains to reduce Se(VI). The results suggest that Se(VI) reduction activity is dependent on enzyme export across the cytoplasmic membrane and that reduction of Se(VI) and Se(IV) are catalyzed by different enzymatic systems.

  9. Plasma chemical reduction of model corrosion brass layers prepared in soil

    NASA Astrophysics Data System (ADS)

    Radkova, Lucie; Mikova, Petra; Prikryl, Radek; Krcma, Frantisek

    2016-08-01

    The brass plates of (50 × 10 × 1) mm3 were prepared with model corrosion layer because the real archaeological artifacts could be damaged during the method optimization. Samples corroded naturally more than 2 years in the soil. Excavated samples were treated in the low pressure (150 Pa) quartz glass plasma reactor (90 cm long and 9.5 cm in diameter) which was surrounded by two external copper electrodes supplied by radio-frequency generator (13.56 MHz). The experiments were carried out in a hydrogen-argon gas mixture at mass flows of 30 sccm for hydrogen and 20 sccm for argon for 90 min. The plasma power was 100, 200, 300 and 400 W in continuous and pulsed mode. Maximum sample temperature was set at 120 °C. The whole process was monitored by optical emission spectroscopy and the obtained data were used to calculate the relative intensity of OH radicals and rotational temperature. The results showed that the higher power had the greater maximum intensity of the OH radicals and rapidly degraded the corrosion layer. Corrosion layer was not completely removed during the reduction, but due to the reactions which occur in the plasma corrosion layer became brittle and after plasma chemical treatment can be removed easily. Finally, the SEM-EDX analysis of the surface composition confirmed removal of chlorine and oxygen from the corrosion products layers. Contribution to the topical issue "6th Central European Symposium on Plasma Chemistry (CESPC-6)", edited by Nicolas Gherardi, Ester Marotta and Cristina Paradisi

  10. Recovery of Cu(II) by chemical reduction using sodium dithionite: effect of pH and ligands.

    PubMed

    Chou, Yi-Hsuan; Yu, Jui-Hsuan; Liang, Yang-Min; Wang, Pin-Jan; Li, Chi-Wang; Chen, Shiao-Shing

    2015-01-01

    Wastewaters containing Cu(II) and ligands are ubiquitous in various industrial sectors, and efficacy of copper removal processes, especially precipitation, is greatly compromised by ligands. Chemical reduction, being commonly employed for production of metal nanoparticles, is also effective for metal removal. Adjustment of pH and addition of ligands are important to control the particle size in metallic nanoparticle production. Exploiting the fact that ligands and metals coexist in many wastewaters, chemical reduction was employed to treat ligand-containing wastewater in this study. The experimental result shows that depending on pH, type of ligands, and copper:ligand molar ratio, copper could be removed by either the reduction or precipitation mechanism. Almost complete copper removal could be achieved by the reduction mechanism under optimal condition for solutions containing either EDTA (ethylenediaminetetraacetic acid) or citrate ligands. For solutions containing ammonia, depending on pH and Cu:ammonia molar ratio, copper was removed by both precipitation and reduction mechanisms. At pH of 9.0, formation of nano-sized particles, which readily pass through a 0.45 μm filter used for sample pretreatment before residual copper analysis, results in the lowest copper removal efficiency. Both cuprous oxide and metallic copper are identified in the solids produced, and the possible explanations are provided. PMID:26606104

  11. Synthesis of silver nanoparticles by chemical reduction at various fraction of MSA and their structure characterization

    NASA Astrophysics Data System (ADS)

    Diantoro, Markus; Fitrianingsih, Rina; Mufti, Nandang; Fuad, Abdulloh

    2014-03-01

    Nanosilver is currently one of the most common engineered nanomaterials and is used in many applications that lead to the release of silver nanoparticles and silver ions into aqueous systems. Nanosilver also possesses enhanced antimicrobial activity and bioavailability that may less environmental risk compared with other manufactured nanomaterials. Described in this research are the synthesis of silver nanoparticle produced by chemical reduction from silver nitrate (AgNO3) solution. As a reducing agent, Sodium Borohydride (NaBH4) was used and mercaptosuccinic Acid (MSA) as stabilizer to prevent the nanoparticle from aglomerating. It was also used two kinds of solvent, they are water and methanol. In typical experiment MSA was dissolve in methanol with a number of variation of molarity i.e. 0,03 M, 0,06 M, 0,12 M, 0,15 M, and the mixture was kept under vigorous stirring in an ice bath. A solution of silver nitrate of 340 mg in 6,792 ml water was added. A freshly prepared aqueous solution of sodium borohydride (756,6 mL in 100 mL of water) was added drop wisely. The solution was kept for half an hour for stirring and were allowed to settle down in methanol. The obtained samples then characterized by means of x-ray diffractometer, and scanning electron microscopy, as well as transmission electron microscopy to obtain their structures of silver nanoparticles, morphology, and sizes. It is shown that diameter of silver nanoparticle sized about 24.3 nm (Ag@MSA 0.03 M), 20.4 nm (Ag@MSA 0.06 M), 16.8 nm (Ag@MSA 0.12 M), 16.9 nm (Ag@MSA 0.15 M) which was calculated by Scherrer formula by taking the FWHM from fitting to Gaussian. The phases and lattice parameter showed that there is no significant change in its volume by increasing molarity of stabilizer. In contrast, the size of particles is decreasing.

  12. Iron isotope fractionation by microbial iron reduction in modern chemically precipitated sediments

    NASA Astrophysics Data System (ADS)

    Roden, E. E.; Tangalos, G. E.; Beard, B. L.; Johnson, C. M.; Alpers, C. N.; Shelobolina, E. S.; Xu, H.; Konishi, H.

    2008-12-01

    Laboratory experiments have demonstrated that dissimilatory microbial iron oxide reduction (DIR) can produce Fe(II) phases that have low 56Fe/54Fe ratios similar to those found in Neoarchean and Paleoproterozoic banded iron formations (BIFs) and shales. Direct application of these experiments to BIF formation has been hindered by the lack of Fe isotope data from modern environments that are analogous to BIFs. Here we report Fe inventories and isotopic compositions for chemically precipitated sediments in the Spring Creek Arm of Keswick Reservoir (SCAKR) downstream of the Iron Mountain acid mine drainage site in northern California, USA. The high concentration of reactive Fe(III) (ca. 50-100 mmol of amorphous Fe(III) oxyhydroxides per liter of bulk sediment) allows dissimilatory iron-reducing bacteria (DIRB) to predominate over dissimilatory sulfate-reducing bacteria in sediment carbon metabolism, making the SCAKR a better analog for BIFs compared to modern marine environments. DIR has generated millimolar concentrations of aqueous Fe(II) (Fe(II)aq) in SCAKR sediments. The Fe(II)aq has lower 56Fe/54Fe values than bulk HCl-extractable Fe; δ56Fe values for bulk HCl-extractable Fe fall within the range previously defined for mafic- to intermediate-composition terrestrial igneous rocks, modern marine sediments, suspended river sediments, Proterozoic-Phanerozoic shales, loess, aerosols, and soils. After removal of pore fluid, sediment was reacted for 1 hr with 0.1M HCl to isolate solid-phase Fe(II) (Fe(II)s), which was likely a mixture of sorbed Fe(II) and amorphous surface-precipitated Fe(II) hydroxide. Subsequent 24-hr extraction with 0.5M HCl recovered amorphous Fe(III) oxide (Fe(III)am). Sediment incubation experiments with SCAKR sediment produced trends in in Fe isotopic fractionations between Fe(II)aq, Fe(II)s, and Fe(III)am analogous to those observed in situ. Collectively the data suggest an equilibrium 56Fe/54Fe isotope fractionation between Fe(II)aq and Fe

  13. Synthesis of silver nanoparticles by chemical reduction at various fraction of MSA and their structure characterization

    SciTech Connect

    Diantoro, Markus Fitrianingsih, Rina Mufti, Nandang Fuad, Abdulloh

    2014-03-24

    Nanosilver is currently one of the most common engineered nanomaterials and is used in many applications that lead to the release of silver nanoparticles and silver ions into aqueous systems. Nanosilver also possesses enhanced antimicrobial activity and bioavailability that may less environmental risk compared with other manufactured nanomaterials. Described in this research are the synthesis of silver nanoparticle produced by chemical reduction from silver nitrate (AgNO{sub 3}) solution. As a reducing agent, Sodium Borohydride (NaBH{sub 4}) was used and mercaptosuccinic Acid (MSA) as stabilizer to prevent the nanoparticle from aglomerating. It was also used two kinds of solvent, they are water and methanol. In typical experiment MSA was dissolve in methanol with a number of variation of molarity i.e. 0,03 M, 0,06 M, 0,12 M, 0,15 M, and the mixture was kept under vigorous stirring in an ice bath. A solution of silver nitrate of 340 mg in 6,792 ml water was added. A freshly prepared aqueous solution of sodium borohydride (756,6 mL in 100 mL of water) was added drop wisely. The solution was kept for half an hour for stirring and were allowed to settle down in methanol. The obtained samples then characterized by means of x-ray diffractometer, and scanning electron microscopy, as well as transmission electron microscopy to obtain their structures of silver nanoparticles, morphology, and sizes. It is shown that diameter of silver nanoparticle sized about 24.3 nm (Ag@MSA 0.03 M), 20.4 nm (Ag@MSA 0.06 M), 16.8 nm (Ag@MSA 0.12 M), 16.9 nm (Ag@MSA 0.15 M) which was calculated by Scherrer formula by taking the FWHM from fitting to Gaussian. The phases and lattice parameter showed that there is no significant change in its volume by increasing molarity of stabilizer. In contrast, the size of particles is decreasing.

  14. Fast variance reduction for steady-state simulation and sensitivity analysis of stochastic chemical systems using shadow function estimators

    SciTech Connect

    Milias-Argeitis, Andreas Khammash, Mustafa; Lygeros, John

    2014-07-14

    We address the problem of estimating steady-state quantities associated to systems of stochastic chemical kinetics. In most cases of interest, these systems are analytically intractable, and one has to resort to computational methods to estimate stationary values of cost functions. In this work, we introduce a novel variance reduction algorithm for stochastic chemical kinetics, inspired by related methods in queueing theory, in particular the use of shadow functions. Using two numerical examples, we demonstrate the efficiency of the method for the calculation of steady-state parametric sensitivities and evaluate its performance in comparison to other estimation methods.

  15. New chemical insights using weakly supported voltammetry: the reductive cleavage of Aryl-Br bonds is reversible.

    PubMed

    Wang, Yijun; Barnes, Edward O; Compton, Richard G

    2012-10-22

    Cyclic voltammetry carried out at a wide range of supporting electrolyte concentrations and compositions can elucidate additional kinetic and mechanistic details of the electrochemical reduction of aryl halides. The cleavage of the C-Br bond is reversible, driven by H abstraction and the second electron transfer. This is a new chemical insight, as the cleavage of such bonds has usually been regarded as irreversible.

  16. Function of a landscape lake in the reduction of biotoxicity related to trace organic chemicals from reclaimed water.

    PubMed

    Ma, Xiaoyan Y; Wang, Xiaochang C; Wang, Donghong; Ngo, Huu Hao; Zhang, Qiuya; Wang, Yongkun; Dai, Dinan

    2016-11-15

    The storage of water in a landscape lake can act as a buffer zone between reclaimed water production and reuse, but there is still uncertainty about the variation of water quality and toxic effects during the open-storage process. In this study, long-term sample collection, chemical analyses and biotoxicity assessments were conducted on reclaimed water before and after open storage in a landscape lake. The organic contents, in terms of chemical oxygen demand and total organic carbon, were found to be slightly higher in the lake water than that in the reclaimed water, but substantial reduction of the total concentration of 52 trace organic chemicals was obtained and microorganism toxicity, phytotoxicity, aquatic vertebrate toxicity and genotoxicity, were significantly weakened after open storage. Furthermore, the total risk quotient (RQTotal) decreased from 5.12 (potential ecological risk level) in the reclaimed water to 0.18 (negligible ecological risk level) in the lake water. The removal of chlorpyrifos, dichlorphos and tetracycline was identified as the main reason for biotoxicity reduction after open storage. The seminatural environment of the landscape lake would have provided a favorable condition for the decay of toxic trace organic chemicals so that the stored water turned to be safer for further reuse. PMID:27475464

  17. Function of a landscape lake in the reduction of biotoxicity related to trace organic chemicals from reclaimed water.

    PubMed

    Ma, Xiaoyan Y; Wang, Xiaochang C; Wang, Donghong; Ngo, Huu Hao; Zhang, Qiuya; Wang, Yongkun; Dai, Dinan

    2016-11-15

    The storage of water in a landscape lake can act as a buffer zone between reclaimed water production and reuse, but there is still uncertainty about the variation of water quality and toxic effects during the open-storage process. In this study, long-term sample collection, chemical analyses and biotoxicity assessments were conducted on reclaimed water before and after open storage in a landscape lake. The organic contents, in terms of chemical oxygen demand and total organic carbon, were found to be slightly higher in the lake water than that in the reclaimed water, but substantial reduction of the total concentration of 52 trace organic chemicals was obtained and microorganism toxicity, phytotoxicity, aquatic vertebrate toxicity and genotoxicity, were significantly weakened after open storage. Furthermore, the total risk quotient (RQTotal) decreased from 5.12 (potential ecological risk level) in the reclaimed water to 0.18 (negligible ecological risk level) in the lake water. The removal of chlorpyrifos, dichlorphos and tetracycline was identified as the main reason for biotoxicity reduction after open storage. The seminatural environment of the landscape lake would have provided a favorable condition for the decay of toxic trace organic chemicals so that the stored water turned to be safer for further reuse.

  18. Reduction of Fe(III)EDTA(-) in a NO(x) scrubbing solution by magnetic Fe3O4-chitosan microspheres immobilized mixed culture of iron-reducing bacteria.

    PubMed

    Jing, Guohua; Zhou, Jin; Zhou, Zuoming; Lin, Tianming

    2012-03-01

    Magnetic Fe(3)O(4)-chitosan microspheres were prepared by co-precipitating of Fe(2+) and Fe(3+) ions with NaOH in the presence of chitosan. The saturated magnetization of the resulting material was 20.0 emu/g. Then these magnetic microspheres were employed to immobilize iron-reducing bacteria to improve the biological reduction of Fe(III)EDTA(-), which was one of the key steps in nitrogen oxides (NO(x)) removal by the integrated chemical absorption-biological reduction process. The immobilized bacteria performed well on Fe(III)EDTA(-) reduction than free bacteria, even under unfavorable pH and temperatures. Furthermore, the effects of NO(2)(-), NO(3)(-), SO(3)(-), and S(2-), the potential inhibition compounds in the scrubber solution, on the reduction of Fe(III)EDTA(-) by the immobilized and free bacteria were also studied. PMID:22281145

  19. Reduction of Salmonella on chicken meat and chicken skin by combined or sequential application of lytic bacteriophage with chemical antimicrobials.

    PubMed

    Sukumaran, Anuraj T; Nannapaneni, Rama; Kiess, Aaron; Sharma, Chander Shekhar

    2015-08-17

    The effectiveness of recently approved Salmonella lytic bacteriophage preparation (SalmoFresh™) in reducing Salmonella in vitro and on chicken breast fillets was examined in combination with lauric arginate (LAE) or cetylpyridinium chloride (CPC). In another experiment, a sequential spray application of this bacteriophage (phage) solution on Salmonella inoculated chicken skin after a 20s dip in chemical antimicrobials (LAE, CPC, peracetic acid, or chlorine) was also examined in reducing Salmonella counts on chicken skin. The application of phage in combination with CPC or LAE reduced S. Typhimurium, S. Heidelberg, and S. Enteritidis up to 5 log units in vitro at 4 °C. On chicken breast fillets, phage in combination with CPC or LAE resulted in significant (p<0.05) reductions of Salmonella ranging from 0.5 to 1.3 log CFU/g as compared to control up to 7 days of refrigerated storage. When phage was applied sequentially with chemical antimicrobials, all the treatments resulted in significant reductions of Salmonella. The application of chlorine (30 ppm) and PAA (400 ppm) followed by phage spray (10(9)PFU/ml) resulted in highest Salmonella reductions of 1.6-1.7 and 2.2-2.5l og CFU/cm(2), respectively. In conclusion, the surface applications of phage in combination with LAE or CPC significantly reduced Salmonella counts on chicken breast fillets. However, higher reductions in Salmonella counts were achieved on chicken skin by the sequential application of chemical antimicrobials followed by phage spray. The sequential application of chlorine, PAA, and phage can provide additional hurdles to reduce Salmonella on fresh poultry carcasses or cut up parts.

  20. Reduction of Salmonella on chicken meat and chicken skin by combined or sequential application of lytic bacteriophage with chemical antimicrobials.

    PubMed

    Sukumaran, Anuraj T; Nannapaneni, Rama; Kiess, Aaron; Sharma, Chander Shekhar

    2015-08-17

    The effectiveness of recently approved Salmonella lytic bacteriophage preparation (SalmoFresh™) in reducing Salmonella in vitro and on chicken breast fillets was examined in combination with lauric arginate (LAE) or cetylpyridinium chloride (CPC). In another experiment, a sequential spray application of this bacteriophage (phage) solution on Salmonella inoculated chicken skin after a 20s dip in chemical antimicrobials (LAE, CPC, peracetic acid, or chlorine) was also examined in reducing Salmonella counts on chicken skin. The application of phage in combination with CPC or LAE reduced S. Typhimurium, S. Heidelberg, and S. Enteritidis up to 5 log units in vitro at 4 °C. On chicken breast fillets, phage in combination with CPC or LAE resulted in significant (p<0.05) reductions of Salmonella ranging from 0.5 to 1.3 log CFU/g as compared to control up to 7 days of refrigerated storage. When phage was applied sequentially with chemical antimicrobials, all the treatments resulted in significant reductions of Salmonella. The application of chlorine (30 ppm) and PAA (400 ppm) followed by phage spray (10(9)PFU/ml) resulted in highest Salmonella reductions of 1.6-1.7 and 2.2-2.5l og CFU/cm(2), respectively. In conclusion, the surface applications of phage in combination with LAE or CPC significantly reduced Salmonella counts on chicken breast fillets. However, higher reductions in Salmonella counts were achieved on chicken skin by the sequential application of chemical antimicrobials followed by phage spray. The sequential application of chlorine, PAA, and phage can provide additional hurdles to reduce Salmonella on fresh poultry carcasses or cut up parts. PMID:25950852

  1. DNAPL mass transfer and permeability reduction during in situ chemical oxidation with permanganate

    NASA Astrophysics Data System (ADS)

    Li, X. David; Schwartz, Franklin W.

    2004-03-01

    This study utilized a series of laboratory experiments to examine the DNAPL mass removal rate and permeability reduction during ISCO using permanganate (MnO4-). Results show that MnO4- oxidation is effective in removing residual DNAPL from a porous medium. The DNAPL mass removal rate correlated positively with both the hydraulic stress and the oxidant load. A power relationship model of DNAPL mass removal under ISCO was proposed. Results also show that oxidation by-products CO2(g) and Mn oxide can cause pore plugging and flow by-passing. The reduction in hydraulic conductivity due to the Mn oxide precipitates was quantified. Hydraulic conductivity reduction as high as 80% was observed for oxidizing a small quantity of TCE.

  2. Integration of polyelectrolyte enhanced ultrafiltration and chemical reduction for metal-containing wastewater treatment and metal recovery.

    PubMed

    Yu, Jui-Hsuan; Chou, Yi-Hsuan; Liang, Yang-Min; Li, Chi-Wang

    2015-01-01

    Chemical reduction was firstly employed to treat synthetic wastewaters of various compositions prepared to simulate the retentate stream of polyelectrolyte enhanced ultrafiltration (PEUF). With fixed Cu:polyethylenimine (PEI) monomer:dithionite molar ratio, increasing copper concentration increases copper removal efficiency. Under fixed Cu:dithionite molar ratio and fixed Cu concentration, increasing PEI monomer:copper molar ratio decreases copper removal efficiency. The formation of nano-sized copper particles, which readily pass through 0.45 μm filter used for sample pretreatment before residual copper analysis, might be the reason behind the decreasing copper removal efficiency observed. Particle size analysis shows that the size of copper particles, which are formed through reduction reaction, increases with decreasing pH value and increasing reaction time. As ultrafiltration is capable of removing these nano-sized particles, integration of chemical reduction and PEUF is proposed to simultaneously achieve regeneration of polyelectrolyte and recovery of copper in one process. Results show that the proposed process could achieve almost complete copper removal without being affected by reaction pH. PMID:26398024

  3. Applying the Philosophical Concept of Reduction to the Chemistry of Water: Implications for Chemical Education

    ERIC Educational Resources Information Center

    Erduran, Sibel

    2005-01-01

    Even though philosophical themes in science education have been advocated for several decades, little attention has been paid to how these themes can be contextualized in the teaching of a particular domain of science. The purpose of this paper is to provide an example theoretical framework for applying a philosophical theme, reduction, in…

  4. Highly Stable and Tunable Chemical Doping of Multilayer WS2 Field Effect Transistor: Reduction in Contact Resistance.

    PubMed

    Khalil, Hafiz M W; Khan, Muhammad Farooq; Eom, Jonghwa; Noh, Hwayong

    2015-10-28

    The development of low resistance contacts to 2D transition-metal dichalcogenides (TMDs) is still a big challenge for the future generation field effect transistors (FETs) and optoelectronic devices. Here, we report a chemical doping technique to achieve low contact resistance by keeping the intrinsic properties of few layers WS2. The transfer length method has been used to investigate the effect of chemical doping on contact resistance. After doping, the contact resistance (Rc) of multilayer (ML) WS2 has been reduced to 0.9 kΩ·μm. The significant reduction of the Rc is mainly due to the high electron doping density, thus a reduction in Schottky barrier height, which limits the device performance. The threshold voltage of ML-WS2 FETs confirms a negative shift upon the chemical doping, as further confirmed from the positions of E(1)2g and A1g peaks in Raman spectra. The n-doped samples possess a high drain current of 65 μA/μm, with an on/off ratio of 1.05 × 10(6) and a field effect mobility of 34.7 cm(2)/(V·s) at room temperature. Furthermore, the photoelectric properties of doped WS2 flakes were also measured under deep ultraviolet light. The potential of using LiF doping in contact engineering of TMDs opens new ways to improve the device performance.

  5. Highly Stable and Tunable Chemical Doping of Multilayer WS2 Field Effect Transistor: Reduction in Contact Resistance.

    PubMed

    Khalil, Hafiz M W; Khan, Muhammad Farooq; Eom, Jonghwa; Noh, Hwayong

    2015-10-28

    The development of low resistance contacts to 2D transition-metal dichalcogenides (TMDs) is still a big challenge for the future generation field effect transistors (FETs) and optoelectronic devices. Here, we report a chemical doping technique to achieve low contact resistance by keeping the intrinsic properties of few layers WS2. The transfer length method has been used to investigate the effect of chemical doping on contact resistance. After doping, the contact resistance (Rc) of multilayer (ML) WS2 has been reduced to 0.9 kΩ·μm. The significant reduction of the Rc is mainly due to the high electron doping density, thus a reduction in Schottky barrier height, which limits the device performance. The threshold voltage of ML-WS2 FETs confirms a negative shift upon the chemical doping, as further confirmed from the positions of E(1)2g and A1g peaks in Raman spectra. The n-doped samples possess a high drain current of 65 μA/μm, with an on/off ratio of 1.05 × 10(6) and a field effect mobility of 34.7 cm(2)/(V·s) at room temperature. Furthermore, the photoelectric properties of doped WS2 flakes were also measured under deep ultraviolet light. The potential of using LiF doping in contact engineering of TMDs opens new ways to improve the device performance. PMID:26434774

  6. Chemical methods for reduction of the transfer of radionuclides to farm animals in semi-natural environments.

    PubMed

    Hove, K

    1993-09-24

    The same chemicals can be used for reduction of radionuclide transfer to animals whether kept on farms or grazing in semi-natural and natural habitats. However, different techniques are required for administration of the active compounds. Dairy ruminants may be treated effectively by inclusion of chemicals in supplemental concentrates. Practical experience gained after the Chernobyl accident has shown that both clay minerals and hexacyanoferrates are effective in preventing high radiocaesium levels in animal products. Chemicals such as bentonite clays and CaCO3, used for reduction of 137Cs and 90Sr transfer respectively, must be fed in hectogram quantities and are only practical for dairy animals in semi-natural ecosystems. Salt licks and sustained release boli with hexacyanoferrates as caesium binders have been developed and used successfully after the Chernobyl accident for meat producing cattle, sheep and reindeer which graze freely for extended periods. Daily doses of 25-300 mg in sheep and 250-2000 mg in cows reduces 137Cs accumulation 2-10-fold. Binders for 90Sr have not been tested in grazing animals. Stable iodine could be provided in salt licks and indwelling rumen boli at rates required to block radioiodine uptake by the thyroid gland. Boli and salt licks are highly cost effective in reducing doses to man when compared to interdiction of food from farm animals. PMID:8248770

  7. Reduction of Cr(VI) to Cr(III) in Artificially-Contaminated Soil using Chemical Reagents

    NASA Astrophysics Data System (ADS)

    Kostarelos, Konstantinos; Rao, Ennio; Reale, Daniela

    2010-05-01

    The presence of hexavalent chromium (CrVI) in soil is an environmental concern due to its effect on human health. The concern arises from the leaching and the seepage of Cr(VI) from soil to groundwater. A remediation approach that has been studied in the literature is that of reducing the hexavalent chromium to its trivalent form using a chemical reagent, namely ferrous sulfate heptahydrate (FeSO4.7H20). In this study, we compared performance of ferrous sulfate heptahydrate to sodium thiosulfate (Na2S2O3), a less costly reductant. The means of measuring the performance of the reductants is the US EPA's Toxicity Characteristic Leaching Procedure (TCLP), which states that the total chromium release from the soil must be less than 5 ppm. Because this treatment approach is pH sensitive and thus, susceptible to acid rain effects, it was studied with the intention that it be coupled with a stabilization/fixation approach so as to provide a second level of treatment; i.e., it is not intended to be the stand-alone treatment approach. In this study, the reductants were initially used to treat a contaminated, artificial soil and allowed to cure for varying time periods to determine the minimum curing time. Contaminated artificial soil were then prepared using the same percentage of white sand, kaolinite clay and potassium chromate and varying amount of water as a function of the humidity of the specimens in order to illucidate the effect of moisture on the reductant performance. Finally, the reductant (either ferrous sulfate heptahydrate or sodium thiosulfate) was added in varying doses to determine the best ratio Cr/reagent dose. Chromium release from the soil was evaluated with a modified Toxicity Characteristic Leaching Procedure (TCLP) test after allowing the samples to cure. Results indicated that chromium(VI) released from the specimens was less than 5 ppm for the samples treated with either ferrous sulfate heptahydrate (99.9% of reduction) and sodium thiosulfate (98

  8. Reduction of Allowed Inventory When Chemicals are Located in Close Proximity with Explosives

    SciTech Connect

    Chong, Y P; Nguyen, S N

    2006-09-27

    The objective of this report is to determine the allowed inventory of chemicals stored in the same bay, building or magazine, i.e., in close proximity, with high explosives (HE) that would, in the event of an accident, result in acceptable risks to colocated workers and the public.

  9. ECO LOGIC INTERNATIONAL GAS-PHASE CHEMICAL REDUCTION PROCESS - THE REACTOR SYSTEM - APPLICATIONS ANALYSIS REPORT

    EPA Science Inventory

    The ELI Eco Logic International Inc. (Eco Logic) process thermally separates organics, then chemically reduces them in a hydrogen atmosphere, converting them to a reformed gas that consists of light hydrocarbons and water. A scrubber treats the reformed gas to remove hydrogen chl...

  10. The Reduction of Microbial and Chemical Contaminants with Selected POU/POE Systems

    EPA Science Inventory

    Centralized drinking water treatment and distribution alone may not always be the most practical or cost-effective option. Also, some consumers seeking a proactive measure to reduce exposure to pathogens and chemicals not currently monitored or regulated might consider employing...

  11. Moisture-induced solid state instabilities in α-chymotrypsin and their reduction through chemical glycosylation

    PubMed Central

    2010-01-01

    Background Protein instability remains the main factor limiting the development of protein therapeutics. The fragile nature (structurally and chemically) of proteins makes them susceptible to detrimental events during processing, storage, and delivery. To overcome this, proteins are often formulated in the solid-state which combines superior stability properties with reduced operational costs. Nevertheless, solid protein pharmaceuticals can also suffer from instability problems due to moisture sorption. Chemical protein glycosylation has evolved into an important tool to overcome several instability issues associated with proteins. Herein, we employed chemical glycosylation to stabilize a solid-state protein formulation against moisture-induced deterioration in the lyophilized state. Results First, we investigated the consequences of moisture sorption on the stability and structural conformation of the model enzyme α-chymotrypsin (α-CT) under controlled humidity conditions. Results showed that α-CT aggregates and inactivates as a function of increased relative humidity (RH). Furthermore, α-CT loses its native secondary and tertiary structure rapidly at increasing RH. In addition, H/D exchange studies revealed that α-CT structural dynamics increased at increasing RH. The magnitude of the structural changes in tendency parallels the solid-state instability data (i.e., formation of buffer-insoluble aggregates, inactivation, and loss of native conformation upon reconstitution). To determine if these moisture-induced instability issues could be ameliorated by chemical glycosylation we proceeded to modify our model protein with chemically activated glycans of differing lengths (lactose and dextran (10 kDa)). The various glycoconjugates showed a marked decrease in aggregation and an increase in residual activity after incubation. These stabilization effects were found to be independent of the glycan size. Conclusion Water sorption leads to aggregation, inactivation

  12. Features in chemical kinetics. I. Signatures of self-emerging dimensional reduction from a general format of the evolution law.

    PubMed

    Nicolini, Paolo; Frezzato, Diego

    2013-06-21

    Simplification of chemical kinetics description through dimensional reduction is particularly important to achieve an accurate numerical treatment of complex reacting systems, especially when stiff kinetics are considered and a comprehensive picture of the evolving system is required. To this aim several tools have been proposed in the past decades, such as sensitivity analysis, lumping approaches, and exploitation of time scales separation. In addition, there are methods based on the existence of the so-called slow manifolds, which are hyper-surfaces of lower dimension than the one of the whole phase-space and in whose neighborhood the slow evolution occurs after an initial fast transient. On the other hand, all tools contain to some extent a degree of subjectivity which seems to be irremovable. With reference to macroscopic and spatially homogeneous reacting systems under isothermal conditions, in this work we shall adopt a phenomenological approach to let self-emerge the dimensional reduction from the mathematical structure of the evolution law. By transforming the original system of polynomial differential equations, which describes the chemical evolution, into a universal quadratic format, and making a direct inspection of the high-order time-derivatives of the new dynamic variables, we then formulate a conjecture which leads to the concept of an "attractiveness" region in the phase-space where a well-defined state-dependent rate function ω has the simple evolution ω[over dot]=-ω(2) along any trajectory up to the stationary state. This constitutes, by itself, a drastic dimensional reduction from a system of N-dimensional equations (being N the number of chemical species) to a one-dimensional and universal evolution law for such a characteristic rate. Step-by-step numerical inspections on model kinetic schemes are presented. In the companion paper [P. Nicolini and D. Frezzato, J. Chem. Phys. 138, 234102 (2013)] this outcome will be naturally related to the

  13. Features in chemical kinetics. I. Signatures of self-emerging dimensional reduction from a general format of the evolution law

    NASA Astrophysics Data System (ADS)

    Nicolini, Paolo; Frezzato, Diego

    2013-06-01

    Simplification of chemical kinetics description through dimensional reduction is particularly important to achieve an accurate numerical treatment of complex reacting systems, especially when stiff kinetics are considered and a comprehensive picture of the evolving system is required. To this aim several tools have been proposed in the past decades, such as sensitivity analysis, lumping approaches, and exploitation of time scales separation. In addition, there are methods based on the existence of the so-called slow manifolds, which are hyper-surfaces of lower dimension than the one of the whole phase-space and in whose neighborhood the slow evolution occurs after an initial fast transient. On the other hand, all tools contain to some extent a degree of subjectivity which seems to be irremovable. With reference to macroscopic and spatially homogeneous reacting systems under isothermal conditions, in this work we shall adopt a phenomenological approach to let self-emerge the dimensional reduction from the mathematical structure of the evolution law. By transforming the original system of polynomial differential equations, which describes the chemical evolution, into a universal quadratic format, and making a direct inspection of the high-order time-derivatives of the new dynamic variables, we then formulate a conjecture which leads to the concept of an "attractiveness" region in the phase-space where a well-defined state-dependent rate function ω has the simple evolution dot{ω }= - ω ^2 along any trajectory up to the stationary state. This constitutes, by itself, a drastic dimensional reduction from a system of N-dimensional equations (being N the number of chemical species) to a one-dimensional and universal evolution law for such a characteristic rate. Step-by-step numerical inspections on model kinetic schemes are presented. In the companion paper [P. Nicolini and D. Frezzato, J. Chem. Phys. 138, 234102 (2013)], 10.1063/1.4809593 this outcome will be naturally

  14. Chemical Fouling Reduction of a Submersible Steel Spectrophotometer in Estuarine Environments Using a Sacrificial Zinc Anode.

    PubMed

    Tait, Zachary S; Thompson, Megan; Stubbins, Aron

    2015-07-01

    The availability of in situ spectrophotometers, such as the S::CAN spectro::lyser, has expanded the possibilities for high-frequency water quality data collection. However, biological and chemical fouling can degrade the performance of in situ spectrophotometers, especially in saline environments with rapid flow rates. A complex freshwater washing system has been previously designed to reduce chemical fouling for the S::CAN spectro::lyser spectrophotometer. In the current study, we present a simpler, cheaper alternative: the attachment of a sacrificial zinc anode. Results are presented detailing the S::CAN spectro::lyser performance with and without the addition of the sacrificial anode. Attachment of the zinc anode provided efficient corrosion protection during 2-wk deployments in a highly dynamic (average tidal range, 2.5 m) saline tidal saltmarsh creek at Groves Creek, Skidaway Institute of Oceanography, Savannah, GA.

  15. Permanent reduction of dissipation in nanomechanical Si resonators by chemical surface protection.

    PubMed

    Tao, Y; Navaretti, P; Hauert, R; Grob, U; Poggio, M; C L Degen

    2015-11-20

    We report on mechanical dissipation measurements carried out on thin (∼100 nm), single-crystal silicon cantilevers with varying chemical surface termination. We find that the 1-2 nm-thick native oxide layer of silicon contributes about 85% to the friction of the mechanical resonance. We show that the mechanical friction is proportional to the thickness of the oxide layer and that it crucially depends on oxide formation conditions. We further demonstrate that chemical surface protection by nitridation, liquid-phase hydrosilylation, or gas-phase hydrosilylation can inhibit rapid oxide formation in air and results in a permanent improvement of the mechanical quality factor between three- and five-fold. This improvement extends to cryogenic temperatures. Presented recipes can be directly integrated with standard cleanroom processes and may be especially beneficial for ultrasensitive nanomechanical force- and mass sensors, including silicon cantilevers, membranes, or nanowires.

  16. Permanent reduction of dissipation in nanomechanical Si resonators by chemical surface protection

    NASA Astrophysics Data System (ADS)

    Tao, Y.; Navaretti, P.; Hauert, R.; Grob, U.; Poggio, M.; Degen, C. L.

    2015-11-01

    We report on mechanical dissipation measurements carried out on thin (˜100 nm), single-crystal silicon cantilevers with varying chemical surface termination. We find that the 1-2 nm-thick native oxide layer of silicon contributes about 85% to the friction of the mechanical resonance. We show that the mechanical friction is proportional to the thickness of the oxide layer and that it crucially depends on oxide formation conditions. We further demonstrate that chemical surface protection by nitridation, liquid-phase hydrosilylation, or gas-phase hydrosilylation can inhibit rapid oxide formation in air and results in a permanent improvement of the mechanical quality factor between three- and five-fold. This improvement extends to cryogenic temperatures. Presented recipes can be directly integrated with standard cleanroom processes and may be especially beneficial for ultrasensitive nanomechanical force- and mass sensors, including silicon cantilevers, membranes, or nanowires.

  17. Chemical Fouling Reduction of a Submersible Steel Spectrophotometer in Estuarine Environments Using a Sacrificial Zinc Anode.

    PubMed

    Tait, Zachary S; Thompson, Megan; Stubbins, Aron

    2015-07-01

    The availability of in situ spectrophotometers, such as the S::CAN spectro::lyser, has expanded the possibilities for high-frequency water quality data collection. However, biological and chemical fouling can degrade the performance of in situ spectrophotometers, especially in saline environments with rapid flow rates. A complex freshwater washing system has been previously designed to reduce chemical fouling for the S::CAN spectro::lyser spectrophotometer. In the current study, we present a simpler, cheaper alternative: the attachment of a sacrificial zinc anode. Results are presented detailing the S::CAN spectro::lyser performance with and without the addition of the sacrificial anode. Attachment of the zinc anode provided efficient corrosion protection during 2-wk deployments in a highly dynamic (average tidal range, 2.5 m) saline tidal saltmarsh creek at Groves Creek, Skidaway Institute of Oceanography, Savannah, GA. PMID:26437114

  18. Electrochemical and Structural Study of a Chemically Dealloyed PtCu Oxygen Reduction Catalyst

    PubMed Central

    Dutta, Indrajit; Carpenter, Michael K; Balogh, Michael P; Ziegelbauer, Joseph M; Moylan, Thomas E; Atwan, Mohammed H; Irish, Nicholas P

    2013-01-01

    A carbon-supported, dealloyed platinum-copper (Pt-Cu) oxygen reduction catalyst was prepared using a multi-step synthetic procedure. Material produced at each step was characterized using high angle annular dark field scanning transmission electron microscopy (HAADF-STEM), electron energy loss spectroscopy (EELS) mapping, x-ray absorption spectroscopy (XAS), x-ray diffraction (XRD), and cyclic voltammetry (CV), and its oxygen reduction reaction (ORR) activity was measured by a thin-film rotating disk electrode (TF-RDE) technique. The initial synthetic step, a co-reduction of metal salts, produced a range of poorly crystalline Pt, Cu, and Pt-Cu alloy nanoparticles that nevertheless exhibited good ORR activity. Annealing this material alloyed the metals and increased particle size and crystallinity. TEM shows the annealed catalyst to include particles of various sizes, large (>25 nm), medium (12–25 nm), and small (<12 nm). Most of the small and medium-sized particles exhibited a partial or complete coreshell (Cu-rich core and Pt shell) structure with the smaller particles typically having more complete shells. The appearance of Pt shells after annealing indicates that they are formed by a thermal diffusion mechanism. Although the specific activity of the catalyst material was more than doubled by annealing, the concomitant decrease in Pt surface area resulted in a drop in its mass activity. Subsequent dealloying of the catalyst by acid treatment to partially remove the copper increased the Pt surface area by changing the morphology of the large and some medium particles to a “Swiss cheese” type structure having many voids. The smaller particles retained their core-shell structure. The specific activity of the catalyst material was little reduced by dealloying, but its mass activity was more than doubled due to the increase in surface area. The possible origins of these results are discussed in this report. PMID:23807900

  19. Tool for the Reduction and Assessment of Chemical and Other Environmental Impacts (TRACI) TRACI version 2.1 User’s Guide

    EPA Science Inventory

    TRACI 2.1 (the Tool for the Reduction and Assessment of Chemical and other environmental Impacts) has been developed for sustainability metrics, life cycle impact assessment, industrial ecology, and process design impact assessment for developing increasingly sustainable products...

  20. Biological reduction of TNT as part of a combined biological-chemical procedure for mineralization.

    PubMed

    Kröger, Mario; Schumacher, Martina E; Risse, Heike; Fels, Gregor

    2004-08-01

    The explosive 2,4,6-trinitrotoluene (TNT), one of the most abundant and persistent contaminants at former armament factories and military sites, was cometabolically reduced by sludge (mixed culture) from a sewage plant in order to facilitate mineralization in a subsequent photochemical treatment. Under aerobic conditions, the main reduction products were aminodinitrotoluenes (ADNTs). A greater amount of the nitroaromatics (ca. 30%) was adsorbed by the sludge as was shown by a complete balance of the process using 14C-TNT. Under anaerobic conditions, TNT was further converted into ADNTs and diaminonitrotoluenes (DANTs) while only negligible adsorption to the sludge occured.

  1. Reduction of the chemical master equation for gene regulatory networks using proper generalized decompositions.

    PubMed

    Ammar, Amine; Cueto, Elías; Chinesta, Francisco

    2012-09-01

    The numerical solution of the chemical master equation (CME) governing gene regulatory networks and cell signaling processes remains a challenging task owing to its complexity, exponentially growing with the number of species involved. Although most of the existing techniques rely on the use of Monte Carlo-like techniques, we present here a new technique based on the approximation of the unknown variable (the probability of having a particular chemical state) in terms of a finite sum of separable functions. In this framework, the complexity of the CME grows only linearly with the number of state space dimensions. This technique generalizes the so-called Hartree approximation, by using terms as needed in the finite sums decomposition for ensuring convergence. But noteworthy, the ease of the approximation allows for an easy treatment of unknown parameters (as is frequently the case when modeling gene regulatory networks, for instance). These unknown parameters can be considered as new space dimensions. In this way, the proposed method provides solutions for any value of the unknown parameters (within some interval of arbitrary size) in one execution of the program.

  2. Functional fixedness and functional reduction as common sense reasonings in chemical equilibrium and in geometry and polarity of molecules

    NASA Astrophysics Data System (ADS)

    Furió, C.; Calatayud, M. L.; Bárcenas, S. L.; Padilla, O. M.

    2000-09-01

    Many of the learning difficulties in the specific domain of chemistry are found not only in the ideas already possessed by students but in the strategic and procedural knowledge that is characteristic of everyday thinking. These defects in procedural knowledge have been described as functional fixedness and functional reduction. This article assesses the procedural difficulties of students (grade 12 and first and third year of university) based on common sense reasoning in two areas of chemistry: chemical equilibrium and geometry and polarity of molecules. In the first area, the theme of external factors affecting equilibria (temperature and concentration change) was selected because the explanations given by the students could be analyzed easily. The existence of a functional fixedness where Le Chatelier's principle was almost exclusively applied by rote could be observed, with this being the cause of the incorrect responses given to the proposed items. Functional fixedness of the Lewis structure also led to an incorrect prediction of molecular geometry. When molecular geometry was correctly determined by the students, it seemed that other methodological or procedural difficulties appeared when the task was to determine molecular polarity. The students showed a tendency, in many cases, to reduce the factors affecting molecular polarity in two possible ways: (a) assuming that polarity depends only on shape (geometric functional reduction) or (b) assuming that molecular polarity depends only on the polarity of bonds (bonding functional reduction).

  3. Kinetics of the chemical reduction of nitrate by zero-valent iron.

    PubMed

    Rodríguez-Maroto, J M; García-Herruzo, F; García-Rubio, A; Gómez-Lahoz, C; Vereda-Alonso, C

    2009-02-01

    The use of reactive barriers is one of the preferred remediation technologies for the remediation of groundwater contamination. An adequate design of these barriers requires the understanding of the kinetics of the reaction between the target contaminant and the solid phase in the barrier. A study of the kinetics between metallic iron and aqueous nitrate is presented in this paper. Published literature regarding this reaction indicates that researchers are far from a consensus about the mechanism of this reaction. This paper presents the results obtained from experiments performed at different constant pH values and iron dosages, together with a mathematical analysis of the kinetic results. We have found that an Eley-Rideal kinetic model yields a good explanation of the relatively complicated dependence between rate of nitrate reduction and the pH value of the solution.

  4. Electrochemical and Structural Study of a Chemically Dealloyed PtCu Oxygen Reduction Catalyst

    SciTech Connect

    Dutta, Indrajit; Carpenter, Michael K.; Balogh, Michael P.; Ziegelbauer, Joseph M.; Moylan, Thomas E.; Atwan, Mohammed H.; Irish, Nicholas P.

    2010-10-22

    A carbon-supported, dealloyed platinum-copper (Pt-Cu) oxygen reduction catalyst was prepared using a multistep synthetic procedure. Material produced at each step was characterized using high-angle annular dark-field scanning transmission electron microscopy, electron energy loss spectroscopy mapping, X-ray absorption spectroscopy, X-ray diffraction, and cyclic voltammetry, and its oxygen reduction reaction (ORR) activity was measured by a thin-film rotating disk electrode technique. The initial synthetic step, a coreduction of metal salts, produced a range of poorly crystalline Pt, Cu, and Pt-Cu alloy nanoparticles that nevertheless exhibited good ORR activity. Annealing this material alloyed the metals and increased particle size and crystallinity. Transmission electron microscopy shows the annealed catalyst to include particles of various sizes, large (>25 nm), medium (12-25 nm), and small (<12 nm). Most of the small and medium-sized particles exhibited a partial or complete core-shell (Cu-rich core and Pt shell) structure with the smaller particles typically having more complete shells. The appearance of Pt shells after annealing indicates that they are formed by a thermal diffusion mechanism. Although the specific activity of the catalyst material was more than doubled by annealing, the concomitant decrease in Pt surface area resulted in a drop in its mass activity. Subsequent dealloying of the catalyst by acid treatment to partially remove the copper increased the Pt surface area by changing the morphology of the large and some medium particles to a 'Swiss cheese' type structure having many voids. The smaller particles retained their core-shell structure. The specific activity of the catalyst material was little reduced by dealloying, but its mass activity was more than doubled due to the increase in surface area. The possible origins of these results are discussed in this report.

  5. Magnetic properties of FeCo alloy nanoparticles synthesized through instant chemical reduction

    NASA Astrophysics Data System (ADS)

    Karipoth, Prakash; Thirumurugan, Arun; Velaga, Srihari; Greneche, Jean-Marc; Justin Joseyphus, R.

    2016-09-01

    The chemical synthesis of shape and composition controlled Fe based binary alloys has been challenging due to the highly oxidizing nature of Fe. Here, we report the physical properties of flower-like Fe50Co50 nanoparticles prepared by a unique polyol process based on the addition of precursors at the elevated temperature. The magnetic properties are correlated through synchrotron radiation based X-ray diffraction and 57Fe Mössbauer spectrometry. Transmission electron microscopy analysis exposed the flower-like morphology of the FeCo particles. The FeCo nanoparticles showed a coercivity of 440 Oe, attributed to the shape anisotropy of the flower-like shape. Room temperature Mössbauer investigation revealed hyperfine fields of 34.9 and 36.7 T, suggesting two different Fe environments in the disordered state. Mössbauer analysis also showed the presence of superparamagnetic Fe-oxide with a relative fraction of 17%.

  6. IN-SITU CHEMICAL STABILIZATION OF METALS AND RADIONUCLIDES THROUGH ENHANCED ANAEROBIC REDUCTIVE PRECIPITATION

    SciTech Connect

    Christopher C. Lutes; Angela Frizzell, PG; Todd A. Thornton; James M. Harrington

    2003-08-01

    The objective of this NETL sponsored bench-scale study was to demonstrate the efficacy of enhanced anaerobic reductive precipitation (EARP) technology for precipitating uranium using samples from contaminated groundwater at the Fernald Closure Project (FCP) in Cincinnati, Ohio. EARP enhances the natural biological reactions in the groundwater through addition of food grade substrates (typically molasses) to drive the oxidative-reductive potential of the groundwater to a lower, more reduced state, thereby precipitating uranium from solution. In order for this in-situ technology to be successful in the long term, the precipitated uranium must not be re-dissolved at an unacceptable rate once groundwater geochemical conditions return to their pretreatment, aerobic state. The approach for this study is based on the premise that redissolution of precipitated uranium will be slowed by several mechanisms including the presence of iron sulfide precipitates and coatings, and sorption onto fresh iron oxides. A bench-scale study of the technology was performed using columns packed with site soil and subjected to a continuous flow of uranium-contaminated site groundwater (476 {micro}g/L). The ''treated'' column received a steady stream of dilute food grade molasses injected into the contaminated influent. Upon attainment of a consistently reducing environment and demonstrated removal of uranium, an iron sulfate amendment was added along with the molasses in the influent solution. After a month long period of iron addition, the treatments were halted, and uncontaminated, aerobic, unamended water was introduced to the treated column to assess rebound of uranium concentrations. In the first two months of treatment, the uranium concentration in the treated column decreased to the clean-up level (30 {micro}g/L) or below, and remained there for the remainder of the treatment period. A brief period of resolubilization of uranium was observed as the treated column returned to aerobic

  7. Photomask defect tracing, analysis, and reduction with chemically amplified resist process

    NASA Astrophysics Data System (ADS)

    Lin, Cheng-ming; Lai, Rick; Huang, W. H.; Wang, B. C.; Chen, C. Y.; Kung, C. H.; Yoo, Chue-San; Chen, Jieh-Jang; Lee, Sheng-Cha

    2003-08-01

    The features of optical proximity correction are becoming very aggressive as production technology migrates into 90nm/130 nm regime. The complicated optical proximity correction (OPC) patterns often result in un-repairable defects, a major yield loss mechanisms in a mask production line. Defect control is increasingly important. A methodology for identifying defect sources and reduction is demonstrated in this paper. The mechanisms and causes of defect formation could be determined with corresponding process step on the strength of sequence inspections. The cause of half-etched opaque defect on negative CAR process was found from PR fragment contamination of e-beam exposure step. After clean-up of e-beam chamber, yield was increased over 20%. Big pinhole defect and contact of AttPSM positive process was found on ADI step. The possible cause was poor CAR adhesion. These two type defects were decreased by modification of developing recipe, special on rinse step. Design experiment with Taguchi method was used to optimize the interactive recipe of plasma descum and rinse step on developing step of implanted layer. Average defect density was decreased from 0.99 to 0.27, and percentage of zero defect rate has been increased from 29.5 to 63.3%.

  8. Reduction of Contaminants (Physical, Chemical, and Microbial) in Domestic Wastewater through Hybrid Constructed Wetland.

    PubMed

    Sehar, Shama; Aamir, Rabia; Naz, Iffat; Ali, Naeem; Ahmed, Safia

    2013-01-01

    The current research was focused mainly on the designing and construction of efficient laboratory scale hybrid constructed wetland (HCW) for the treatment of domestic wastewater. Parameters like COD, BOD5, PO4, SO4, NO3, NO2, and pathogenic indicator microbes were monitored after hydraulic retention time (HRT) of 4, 8, 12, 16, and 20 days. Treatment efficiency of HCW kept on increasing with the increase in hydraulic retention time. Maximum efficiency of HCW was observed with a 20-day HRT, that is, 97.55, 97.5, 89.35, 80.75, 96.04, 91.52, and 98.6% reduction from the zero time value for COD, BOD5, PO4, SO4, NO3, NO2, and fecal coliforms, respectively. After 20 days' time, the treated water was free of almost all nutrients and microbial pollutants. Hence, increasing hydraulic retention time was found to ameliorate the operational competence of HCW. Thus HCW can serve as a promising technology for wastewater treatment and can be scaled up for small communities in the developing countries.

  9. Reduction of Contaminants (Physical, Chemical, and Microbial) in Domestic Wastewater through Hybrid Constructed Wetland

    PubMed Central

    Sehar, Shama; Aamir, Rabia; Naz, Iffat; Ali, Naeem; Ahmed, Safia

    2013-01-01

    The current research was focused mainly on the designing and construction of efficient laboratory scale hybrid constructed wetland (HCW) for the treatment of domestic wastewater. Parameters like COD, BOD5, PO4, SO4, NO3, NO2, and pathogenic indicator microbes were monitored after hydraulic retention time (HRT) of 4, 8, 12, 16, and 20 days. Treatment efficiency of HCW kept on increasing with the increase in hydraulic retention time. Maximum efficiency of HCW was observed with a 20-day HRT, that is, 97.55, 97.5, 89.35, 80.75, 96.04, 91.52, and 98.6% reduction from the zero time value for COD, BOD5, PO4, SO4, NO3, NO2, and fecal coliforms, respectively. After 20 days' time, the treated water was free of almost all nutrients and microbial pollutants. Hence, increasing hydraulic retention time was found to ameliorate the operational competence of HCW. Thus HCW can serve as a promising technology for wastewater treatment and can be scaled up for small communities in the developing countries. PMID:23724336

  10. Synthesis of reduced graphene oxide (rGO) via chemical reduction

    SciTech Connect

    Thakur, Alpana Rangra, V. S.; Kumar, Sunil

    2015-05-15

    Natural flake Graphite was used as the starting material for the graphene synthesis. In the first step flake graphite was treated with oxidizing agents under vigorous conditions to obtain graphite oxide. Layered graphite oxide decorated with oxygen has large inter-layer distance leading easy exfoliation into single sheets by ultrasonication giving graphene oxide. In the last step exfoliated graphene oxide sheets were reduced slowly with the help of reducing agent to obtain fine powder which is labeled as reduced graphene oxide (rGO). This rGO was further characterized by X-Ray Diffraction (XRD), Scanning Tunneling Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy techniques. XRD pattern shows peaks corresponding to (002) graphitic lattice planes indicating the formation of network of sp{sup 2} like carbon structure. SEM images show the ultrathin, wrinkled, paper-like morphology of graphene sheets. IR study shows that the graphite has been oxidized to graphite oxide with the presence of various absorption bands confirming the presence of oxidizing groups. The FTIR spectrum of rGO shows no sharp peaks confirming the efficient reduction of rGO. The Raman spectrum shows disorder in the graphene sheets.

  11. Quantifying the value of information for uncertainty reduction in chemical EOR modeling

    NASA Astrophysics Data System (ADS)

    Leray, Sarah; Yeates, Christopher; Douarche, Frédéric; Roggero, Frédéric

    2016-04-01

    Reservoir modeling is a powerful tool to assess the technical and economic feasibility of chemical Enhanced Oil Recovery methods such as the joint injection of surfactant and polymer. Laboratory recovery experiments are usually undertaken on cores to understand recovery mechanisms and to estimate properties, that will be further used to build large scale models. To capture the different processes involved in chemical EOR, models are described by a large number of parameters which are basically only partially constrained by recovery experiments and additional characterizations, mainly because of cost and time restrictions or limited representativeness. Among the most uncertain properties, features the surfactant adsorption which cannot be straightforwardly derived from bulk or simplified dynamic measurements (e.g. single phase dynamic adsorption experiments). It is unfortunately critical for the economics of the process. Identifying the most informative observations (e.g. saturation scans, pressure differential, surfactant production, oil recovery) is of primary interest to compensate deficiency of some characterizations and improve models robustness and their predictive capability. Building a consistent set of recovery experiments that will allow to seize recovery mechanisms is critical as well. To address these inverse methodology issues, we create a synthetic numerical model with a well-defined set of parameter values, considered to be our reference case. This choice of model is based on a similar real data set and a broad literature review. It consists of a water-wet sandstone subject to typical surfactant-polymer injections. We first study the effect of a salinity gradient injected after a surfactant-polymer slug, as it is known to significantly improve oil recovery. We show that reaching optimal conditions of salinity gradient is a fragile balance between surfactant desorption and interfacial tension increase. This high dependence on surfactant adsorption

  12. Kondo effect in Co{sub x}Cu{sub 1-x} granular alloys prepared by chemical reduction method

    SciTech Connect

    Dhara, Susmita Chowdhury, Rajeswari Roy; Bandyopadhyay, Bilwadal

    2015-06-24

    Nanostructured CoCu granular alloys Co{sub x}Cu{sub 1-x} (x ≤ 0.3) have been prepared by chemical reduction method using NaBH{sub 4} as a reducing agent. Electronic transport properties are studied in the temperature range 4-300 K. Resistance exhibits a metallic behavior below room temperature and draws a minimum near 20 K in all the samples except in Co{sub 0.3}Cu{sub 0.7}. This low temperature resistivity minimum diminishes with applied magnetic field. There is also a logarithmic temperature dependence of resistivity at temperatures below 20 K. This phenomenon indicates a Kondo-like scattering mechanism involving magnetic Co impurity spin clusters in Cu host.

  13. Three Dimensional P-doped Graphene Synthesized by Eco-Friendly Chemical Vapor Deposition for Oxygen Reduction Reactions.

    PubMed

    Li, Xiaoguang; Qiu, Yunfeng; Hu, Ping An

    2016-06-01

    Heteroatom doping provides possibilities for changing the electronic properties of graphene. Three Dimensional P-doped graphene (3DPG) was fabricated via chemical vapor deposition (CVD) using nickel foam as template and triphenylphosphine (TPP) as C and P sources simultaneously without using toxic organic solvent as carrier liquid. The invasion of P atoms into graphene networks make them non-electroneutral and consequently favor the adsorption of oxygen and O-O bond cleavage due to the charge polarization increase of the P-C bond. Thus, the as-prepared 3DPG served as an efficient electrocatalyst for oxygen reduction reaction (ORR). Additionally, the 3D porous structure is favorable for the mass transfer of electrolytes ions, hence 3DPG exhibit better electrocatalytic activity, long-term stability, and tolerance to crossover effect of methanol than pristine 3D graphene and Pt/C for ORR.

  14. Response Behaviour of a Hydrogen Sensor Based on Ionic Conducting Polymer-metal Interfaces Prepared by the Chemical Reduction Method

    PubMed Central

    Sakthivel, Mariappan; Weppner, Werner

    2006-01-01

    A solid-state amperometric hydrogen sensor based on a protonated Nafion membrane and catalytic active electrode operating at room temperature was fabricated and tested. Ionic conducting polymer-metal electrode interfaces were prepared chemically by using the impregnation-reduction method. The polymer membrane was impregnated with tetra-ammine platinum chloride hydrate and the metal ions were subsequently reduced by using either sodium tetrahydroborate or potassium tetrahydroborate. The hydrogen sensing characteristics with air as reference gas is reported. The sensors were capable of detecting hydrogen concentrations from 10 ppm to 10% in nitrogen. The response time was in the range of 10-30 s and a stable linear current output was observed. The thin Pt films were characterized by XRD, Infrared Spectroscopy, Optical Microscopy, Atomic Force Microscopy, Scanning Electron Microscopy and EDAX.

  15. Efficiency of some soil bacteria for chemical oxygen demand reduction of synthetic chlorsulfuron solutions under agiated culture conditions.

    PubMed

    Erguven, G O; Yildirim, N

    2016-01-01

    This study searches the efficiency of certain soil bacteria on chemical oxygen demand (COD) reduction of synthetic chlorsulfuron solutions under agitated culture conditions. It also aims to determine the turbidity of liquid culture medium with chlorsulfuron during bacterial incubation for 120 hours. As a result the highest and lowest COD removal efficiency of bacteria was determined for Bacillus simplex as 94% and for Micrococcus luteus as 70%, respectively at the end of the 96th hour. It was found that COD removal efficiency showed certain differences depend on the bacterial species. It was also observed that B. simplex had the highest COD removal efficiency and it was a suitable bacterium species for bioremediation of a chlorsulfuron contaminated soils. PMID:27262810

  16. Determination of decimal reduction time (D value) of chemical agents used in hospitals for disinfection purposes

    PubMed Central

    Mazzola, Priscila Gava; Penna, Thereza Christina Vessoni; da S Martins, Alzira M

    2003-01-01

    Background Prior to the selection of disinfectants for low, intermediate and high (sterilizing) levels, the decimal reduction time, D-value, for the most common and persistent bacteria identified at a health care facility should be determined. Methods The D-value was determined by inoculating 100 mL of disinfecting solution with 1 mL of a bacterial suspension (104 – 105 CFU/mL for vegetative and spore forms). At regular intervals, 1 mL aliquots of this mixture were transferred to 8 mL of growth media containing a neutralizing agent, and incubated at optimal conditions for the microorganism. Results The highest D-values for various bacteria were determined for the following solutions: (i) 0.1% sodium dichloroisocyanurate (pH 7.0) – E. coli and A. calcoaceticus (D = 5.9 min); (ii) sodium hypochlorite (pH 7.0) at 0.025% for B. stearothermophilus (D = 24 min), E. coli and E. cloacae (D = 7.5 min); at 0.05% for B. stearothermophilus (D = 9.4 min) and E. coli (D = 6.1 min) and 0.1% for B. stearothermophilus (D = 3.5 min) and B. subtilis (D = 3.2 min); (iii) 2.0% glutaraldehyde (pH 7.4) – B. stearothermophilus, B. subtilis (D = 25 min) and E. coli (D = 7.1 min); (iv) 0.5% formaldehyde (pH 6.5) – B. subtilis (D = 11.8 min), B. stearothermophilus (D = 10.9 min) and A. calcoaceticus (D = 5.2 min); (v) 2.0% chlorhexidine (pH 6.2) – B. stearothermophilus (D = 9.1 min), and at 0.4% for E. cloacae (D = 8.3 min); (vi) 1.0% Minncare® (peracetic acid and hydrogen peroxide, pH 2.3) – B. stearothermophilus (D = 9.1 min) and E. coli (D = 6.7 min). Conclusions The suspension studies were an indication of the disinfectant efficacy on a surface. The data in this study reflect the formulations used and may vary from product to product. The expected effectiveness from the studied formulations showed that the tested agents can be recommended for surface disinfection as stated in present guidelines and emphasizes the importance and need to develop routine and novel programs to

  17. Synthesis and characterization of silver/montmorillonite/chitosan bionanocomposites by chemical reduction method and their antibacterial activity.

    PubMed

    Shameli, Kamyar; Bin Ahmad, Mansor; Zargar, Mohsen; Yunus, Wan Md Zin Wan; Ibrahim, Nor Azowa; Shabanzadeh, Parvaneh; Moghaddam, Mansour Ghaffari

    2011-01-01

    Silver nanoparticles (AgNPs) of a small size were successfully synthesized using the wet chemical reduction method into the lamellar space layer of montmorillonite/chitosan (MMT/Cts) as an organomodified mineral solid support in the absence of any heat treatment. AgNO3, MMT, Cts, and NaBH4 were used as the silver precursor, the solid support, the natural polymeric stabilizer, and the chemical reduction agent, respectively. MMT was suspended in aqueous AgNO3/Cts solution. The interlamellar space limits were changed (d-spacing = 1.24-1.54 nm); therefore, AgNPs formed on the interlayer and external surface of MMT/Cts with d-average = 6.28-9.84 nm diameter. Characterizations were done using different methods, ie, ultraviolet-visible spectroscopy, powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray fluorescence spectrometry, and Fourier transform infrared spectroscopy. Silver/montmorillonite/chitosan bionanocomposite (Ag/MMT/Cts BNC) systems were examined. The antibacterial activity of AgNPs in MMT/Cts was investigated against Gram-positive bacteria, ie, Staphylococcus aureus and methicillin-resistant S. aureus and Gram-negative bacteria, ie, Escherichia coli, E. coli O157:H7, and Pseudomonas aeruginosa by the disc diffusion method using Mueller Hinton agar at different sizes of AgNPs. All of the synthesized Ag/MMT/Cts BNCs were found to have high antibacterial activity. These results show that Ag/MMT/Cts BNCs can be useful in different biological research and biomedical applications, including surgical devices and drug delivery vehicles.

  18. Synthesis and characterization of silver/montmorillonite/chitosan bionanocomposites by chemical reduction method and their antibacterial activity

    PubMed Central

    Shameli, Kamyar; Ahmad, Mansor Bin; Zargar, Mohsen; Yunus, Wan Md Zin Wan; Ibrahim, Nor Azowa; Shabanzadeh, Parvaneh; Moghaddam, Mansour Ghaffari

    2011-01-01

    Silver nanoparticles (AgNPs) of a small size were successfully synthesized using the wet chemical reduction method into the lamellar space layer of montmorillonite/chitosan (MMT/Cts) as an organomodified mineral solid support in the absence of any heat treatment. AgNO3, MMT, Cts, and NaBH4 were used as the silver precursor, the solid support, the natural polymeric stabilizer, and the chemical reduction agent, respectively. MMT was suspended in aqueous AgNO3/Cts solution. The interlamellar space limits were changed (d-spacing = 1.24–1.54 nm); therefore, AgNPs formed on the interlayer and external surface of MMT/Cts with d-average = 6.28–9.84 nm diameter. Characterizations were done using different methods, ie, ultraviolet-visible spectroscopy, powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray fluorescence spectrometry, and Fourier transform infrared spectroscopy. Silver/montmorillonite/chitosan bionanocomposite (Ag/MMT/Cts BNC) systems were examined. The antibacterial activity of AgNPs in MMT/Cts was investigated against Gram-positive bacteria, ie, Staphylococcus aureus and methicillin-resistant S. aureus and Gram-negative bacteria, ie, Escherichia coli, E. coli O157:H7, and Pseudomonas aeruginosa by the disc diffusion method using Mueller Hinton agar at different sizes of AgNPs. All of the synthesized Ag/MMT/Cts BNCs were found to have high antibacterial activity. These results show that Ag/MMT/Cts BNCs can be useful in different biological research and biomedical applications, including surgical devices and drug delivery vehicles. PMID:21499424

  19. Chemical and Microbial Characterization of North Slope Viscous Oils to Assess Viscosity Reduction and Enhanced Recovery

    SciTech Connect

    Shirish Patil; Abhijit Dandekar; Mary Beth Leigh

    2008-12-31

    A large proportion of Alaska North Slope (ANS) oil exists in the form of viscous deposits, which cannot be produced entirely using conventional methods. Microbially enhanced oil recovery (MEOR) is a promising approach for improving oil recovery for viscous deposits. MEOR can be achieved using either ex situ approaches such as flooding with microbial biosurfactants or injection of exogenous surfactant-producing microbes into the reservoir, or by in situ approaches such as biostimulation of indigenous surfactant-producing microbes in the oil. Experimental work was performed to analyze the potential application of MEOR to the ANS oil fields through both ex situ and in situ approaches. A microbial formulation containing a known biosurfactant-producing strain of Bacillus licheniformis was developed in order to simulate MEOR. Coreflooding experiments were performed to simulate MEOR and quantify the incremental oil recovery. Properties like viscosity, density, and chemical composition of oil were monitored to propose a mechanism for oil recovery. The microbial formulation significantly increased incremental oil recovery, and molecular biological analyses indicated that the strain survived during the shut-in period. The indigenous microflora of ANS heavy oils was investigated to characterize the microbial communities and test for surfactant producers that are potentially useful for biostimulation. Bacteria that reduce the surface tension of aqueous media were isolated from one of the five ANS oils (Milne Point) and from rock oiled by the Exxon Valdez oil spill (EVOS), and may prove valuable for ex situ MEOR strategies. The total bacterial community composition of the six different oils was evaluated using molecular genetic tools, which revealed that each oil tested possessed a unique fingerprint indicating a diverse bacterial community and varied assemblages. Collectively we have demonstrated that there is potential for in situ and ex situ MEOR of ANS oils. Future work

  20. Effects of regional reductions in sulphur deposition on the chemical and biological recovery of lakes within Killarney Park, Ontario, Canada.

    PubMed

    Snucins, E; Gunn, J; Keller, B; Dixit, S; Hindar, A; Henriksen, A

    2001-01-01

    The lakes in Killarney Provincial Park, located 40-60 km southwest of Sudbury, Ontario, were some of the first lakes in North America to be acidified by atmospheric pollutants. Acidification affected thousands of fish and invertebrate populations in dozens of lakes. Since the 1970's, water quality has improved in response to atmospheric pollution reductions and some lakes have already recovered to approximately their pre-industrial pH levels, as inferred from diatom microfossils in lake sediments. Since the 1970's, fish species richness has not changed substantially, but zooplankton species richness has increased in acidified lakes. The critical sulphur load, the amount of SO2-derived acid deposition that can occur while still maintaining suitable water quality, was estimated to be exceeded in 38% of the park area in 1997. Depending on which of four possible North American emission control scenarios (CLR = currently legislated reduction; CLR + 25%; CLR + 50%; CLR + 75%) is achieved by 2010, the projected critical loads will be exceeded in about 0-30% of the park area in the future. There are many factors that can affect biological recovery rates of damaged lakes, but it is expected that biological recovery will lag considerably behind observed chemical recovery rates.

  1. Direct growth of tellurium nanorod arrays on Pt/FTO/glass through a surfactant-assisted chemical reduction.

    PubMed

    Liu, Hongmei; Zeng, Boming; Jia, Falong

    2011-07-29

    Uniform tellurium nanorod arrays (TNA) have been successfully deposited directly on Pt/FTO (F-doped SnO(2))/glass substrate through a facile surfactant-assisted approach, which involved chemical reduction of TeO(3)(2-) ions by hydrazine hydrate. The whole synthesis process is highly repeatable and performed simply by immersing the Pt/FTO/glass in the solution for a certain time. During the growth of TNA, Pt catalyzed the reduction of TeO(3)(2-) ions by hydrazine hydrate and Te nanoparticles were deposited firmly on the substrate at first. Then, under the regulation of the surfactant (cetyltrimethylammonium bromide, CTAB), the deposited Te grew into nanorod arrays and adhered firmly to the substrate. Similar Te nanorod arrays could also grow on a Pd substrate which has the same catalytic performance as that of Pt. The as-synthesized TNA could be used as a good template to synthesize platinum-and gold-coated nanorods through convenient galvanic replacement. As a demonstration of potential application, the gold/tellurium nanorods showed uniform surface-enhanced Raman scattering (SERS) using rhodamine 6G (Rh6G) as the analyte. This approach provides a simple route for the growth of standing Te nanorods on a substrate, which may be used for the synthesis of other standing one-dimensional materials through a similar mechanism. PMID:21719969

  2. Direct growth of tellurium nanorod arrays on Pt/FTO/glass through a surfactant-assisted chemical reduction

    NASA Astrophysics Data System (ADS)

    Liu, Hongmei; Zeng, Boming; Jia, Falong

    2011-07-01

    Uniform tellurium nanorod arrays (TNA) have been successfully deposited directly on Pt/FTO (F-doped SnO2)/glass substrate through a facile surfactant-assisted approach, which involved chemical reduction of TeO32 - ions by hydrazine hydrate. The whole synthesis process is highly repeatable and performed simply by immersing the Pt/FTO/glass in the solution for a certain time. During the growth of TNA, Pt catalyzed the reduction of TeO32 - ions by hydrazine hydrate and Te nanoparticles were deposited firmly on the substrate at first. Then, under the regulation of the surfactant (cetyltrimethylammonium bromide, CTAB), the deposited Te grew into nanorod arrays and adhered firmly to the substrate. Similar Te nanorod arrays could also grow on a Pd substrate which has the same catalytic performance as that of Pt. The as-synthesized TNA could be used as a good template to synthesize platinum-and gold-coated nanorods through convenient galvanic replacement. As a demonstration of potential application, the gold/tellurium nanorods showed uniform surface-enhanced Raman scattering (SERS) using rhodamine 6G (Rh6G) as the analyte. This approach provides a simple route for the growth of standing Te nanorods on a substrate, which may be used for the synthesis of other standing one-dimensional materials through a similar mechanism.

  3. Organic reactions for the electrochemical and photochemical production of chemical fuels from CO2--The reduction chemistry of carboxylic acids and derivatives as bent CO2 surrogates.

    PubMed

    Luca, Oana R; Fenwick, Aidan Q

    2015-11-01

    The present review covers organic transformations involved in the reduction of CO2 to chemical fuels. In particular, we focus on reactions of CO2 with organic molecules to yield carboxylic acid derivatives as a first step in CO2 reduction reaction sequences. These biomimetic initial steps create opportunities for tandem electrochemical/chemical reductions. We draw parallels between long-standing knowledge of CO2 reactivity from organic chemistry, organocatalysis, surface science and electrocatalysis. We point out some possible non-faradaic chemical reactions that may contribute to product distributions in the production of solar fuels from CO2. These reactions may be accelerated by thermal effects such as resistive heating and illumination.

  4. Study of Impacts of Arctic Sea Ice Reduction on Atmospheric Chemical Processes - The BROMEX 2012 Field Campaign

    NASA Astrophysics Data System (ADS)

    Nghiem, S. V.

    2012-12-01

    Arctic perennial sea ice has decreased drastically in the last decade and still remained low in spring 2012 as observed from scatterometer datasets acquired by QuikSCAT and Oceansat-2 satellites. In particular, the thinner, weaker, and saltier seasonal sea ice has dominated over the perennial ice in the Chukchi Sea and Beaufort Sea. To investigate impacts of sea ice reduction on atmospheric chemical processes, we conducted the BRomine, Ozone, and Mercury EXperiment in (BROMEX) in March-April 2012 around Barrow, extending out to a large region offshore and inland. Here we present overview results from BROMEX, which was successfully carried out by about 30 scientists, researchers, and field workers from multiple international institutions. For BROMEX, we coordinated and collected satellite data, including a number of near-real-time products, from multiple satellite instruments including MODIS, AMSR-E, GOME-2, SCIAMACHY, OMI, RADARSAT-2, Envisat ASAR, TanDEM-X, SMOS, CryoSat-2, and Oceansat-2. Over the BROMEX field region, we made measurements and collected sea ice, snow, ocean, and air samples for physical, meteorological, chemical, biological, and acoustic studies. A helicopter was used to deploy chemical and meteorological buoys in the Chukchi Sea and the Beaufort Sea. Measurements were also made with airborne sensors across sea ice, leads, lagoon, and tundra along various flight patterns of the ALAR aircraft. Furthermore, we coordinated with the NASA IceBridge P3 aircraft to collect surface temperature, surface height, snow depth, and ice thickness measurements. We set up and maintained field sites on sea ice and in the tundra to measure bromine, ozone, mercury, and other chemical species. Moreover, we obtained temperature data from many different types of temperature sensors for temperature accuracy assessment to identify potential issues that might cause errors or biases in temperature measurements. An enormous amount of in-situ snow and ice data was collected

  5. NITRO-HYDROLYSIS: AN ENERGY EFFICIENT SOURCE REDUCTION AND CHEMICAL PRODUCTION PROCESS FOR WASTEWATER TREATMENT PLANT BIOSOLIDS

    SciTech Connect

    Klasson, KT

    2003-03-10

    The nitro-hydrolysis process has been demonstrated in the laboratory in batch tests on one municipal waste stream. This project was designed to take the next step toward commercialization for both industrial and municipal wastewater treatment facility (WWTF) by demonstrating the feasibility of the process on a small scale. In addition, a 1-lb/hr continuous treatment system was constructed at University of Tennessee to treat the Kuwahee WWTF (Knoxville, TN) sludge in future work. The nitro-hydrolysis work was conducted at University of Tennessee in the Chemical Engineering Department and the gas and liquid analysis were performed at Oak Ridge National Laboratory. Nitro-hydrolysis of sludge proved a very efficient way of reducing sludge volume, producing a treated solution which contained unreacted solids (probably inorganics such as sand and silt) that settled quickly. Formic acid was one of the main organic acid products of reaction when larger quantities of nitric acid were used in the nitrolysis. When less nitric acid was used formic acid was initially produced but was later consumed in the reactions. The other major organic acid produced was acetic acid which doubled in concentration during the reaction when larger quantities of nitric acid were used. Propionic acid and butyric acid were not produced or consumed in these experiments. It is projected that the commercial use of nitro-hydrolysis at municipal wastewater treatment plants alone would result in a total estimated energy savings of greater than 20 trillion Btu/yr. A net reduction of 415,000 metric tons of biosolids per year would be realized and an estimated annual cost reduction of $122M/yr.

  6. Improving subjective pattern recognition in chemical senses through reduction of nonlinear effects in evaluation of sparse data

    NASA Astrophysics Data System (ADS)

    Assadi, Amir H.; Rasouli, Firooz; Wrenn, Susan E.; Subbiah, M.

    2002-11-01

    Artificial neural network models are typically useful in pattern recognition and extraction of important features in large data sets. These models are implemented in a wide variety of contexts and with diverse type of input-output data. The underlying mathematics of supervised training of neural networks is ultimately tied to the ability to approximate the nonlinearities that are inherent in network"s generalization ability. The quality and availability of sufficient data points for training and validation play a key role in the generalization ability of the network. A potential domain of applications of neural networks is in analysis of subjective data, such as in consumer science, affective neuroscience and perception of chemical senses. In applications of ANN to subjective data, it is common to rely on knowledge of the science and context for data acquisition, for instance as a priori probabilities in the Bayesian framework. In this paper, we discuss the circumstances that create challenges for success of neural network models for subjective data analysis, such as sparseness of data and cost of acquisition of additional samples. In particular, in the case of affect and perception of chemical senses, we suggest that inherent ambiguity of subjective responses could be offset by a combination of human-machine expert. We propose a method of pre- and post-processing for blind analysis of data that that relies on heuristics from human performance in interpretation of data. In particular, we offer an information-theoretic smoothing (ITS) algorithm that optimizes that geometric visualization of multi-dimensional data and improves human interpretation of the input-output view of neural network implementations. The pre- and post-processing algorithms and ITS are unsupervised. Finally, we discuss the details of an example of blind data analysis from actual taste-smell subjective data, and demonstrate the usefulness of PCA in reduction of dimensionality, as well as ITS.

  7. Red blood cells donate electrons to methylene blue mediated chemical reduction of methemoglobin compartmentalized in liposomes in blood.

    PubMed

    Sakai, Hiromi; Li, Bing; Lim, Wei Lee; Iga, Yumika

    2014-07-16

    Electron-energy-rich coenzymes in cells, NADH and NADPH, are re-energized repeatedly through the Embden-Meyerhof and pentose-phosphate glycolytic pathways, respectively. This study demonstrates extraction of their electron energies in red blood cells (RBCs) for in vivo extracellular chemical reactions using an electron mediator shuttling across the biomembrane. Hemoglobin-vesicles (HbVs) are an artificial oxygen carrier encapsulating purified and concentrated Hb solution in liposomes. Because of the absence of a metHb-reducing enzymatic system in HbV, HbO2 gradually autoxidizes to form metHb. Wistar rats received HbV suspension (10 mL/kg body weight) intravenously. At the metHb level of around 50%, methylene blue [MB(+); 3,7-bis(dimethylamino)phenothiazinium chloride] was injected. The level of metHb quickly decreased to around 16% in 40 min, remaining for more than 5 h. In vitro mixing of HbV/MB(+) with RBCs recreated the in vivo metHb reduction, but not with plasma. NAD(P)H levels in RBCs decreased after metHb reduction. The addition of glucose facilitated metHb reduction. Liposome-encapsulated NAD(P)H, a model of RBC, reduced metHb in HbV in the presence of MB(+). These results indicate that (i) NAD(P)H in RBCs reacts with MB(+) to convert it to leukomethylene blue (MBH); (ii) MB(+) and MBH shuttle freely between RBC and HbV across the hydrophobic lipid membranes; and (iii) MBH is transferred into HbV and reduces metHb in HbV. Four other electron mediators with appropriate redox potentials appeared to be as effective as MB(+) was, indicating the possibility for further optimization of electron mediators. We established an indirect enzymatic metHb reducing system for HbV using unlimited endogenous electrons created in RBCs in combination with an effective electron mediator that prolongs the functional lifespan of HbV in blood circulation.

  8. Application of integrated ozone and granular activated carbon for decolorization and chemical oxygen demand reduction of vinasse from alcohol distilleries.

    PubMed

    Hadavifar, Mojtaba; Younesi, Habibollah; Zinatizadeh, Ali Akbar; Mahdad, Faezeh; Li, Qin; Ghasemi, Zahra

    2016-04-01

    This study investigates the treatment of the distilleries vinasse using a hybrid process integrating ozone oxidation and granular activated carbons (GAC) in both batch and continuous operation mode. The batch-process studies have been carried out to optimize initial influent pH, GAC doses, the effect of the ozone (O3) and hydrogen peroxide (H2O2) concentrations on chemical oxygen demand (COD) and color removal of the distilleries vinasse. The continuous process was carried out on GAC and ozone treatment alone as well as the hybrid process comb both methods to investigate the synergism effectiveness of the two methods for distilleries vinasse COD reduction and color removal. In a continuous process, the Yan model described the experimental data better than the Thomas model. The efficiency of ozonation of the distilleries vinasse was more effective for color removal (74.4%) than COD removal (25%). O3/H2O2 process was not considerably more effective on COD and color removal. Moreover, O3/GAC process affected negatively on the removal efficiency by reducing COD and color from distilleries vinasse. The negative effect decreased by increasing pH value of the influent. PMID:26789200

  9. Sulfur and ash reduction potential and selected chemical and physical properties of United States coals. [Contains glossary

    SciTech Connect

    Cavallaro, J.A.; Deurbrouck, A.W.; Killmeyer, R.P.; Fuchs, W. . Coal Preparation Div.); Jacobsen, P.S. )

    1991-02-01

    This report presents the washability and comprehensive characterization results of 184 raw coal channel samples, including anthracite, bituminous and lignite coals, collected from the Central Region of the United States. This is the second of a three volume report on the coals of the United States. All the data are presented in six appendices. Statistical techniques and definitions are presented in Appendix A, and a glossary of terms is presented in Appendix B. The complete washability data and an in-depth characterization of each sample are presented alphabetically by state in Appendix C. In Appendix D, a statistical evaluation is given for the composited washability data, selected chemical and physical properties and washability data interpolated at various levels of Btu recovery. This presentation is shown by state, section, and region where four or more samples were collected. Appendix E presents coalbed codes and names for the Central Region coals. Graphical summations are presented by state, section and region showing the effects of crushing on impurity reductions, and the distribution of raw and clean coal samples meeting various levels of SO{sub 2} emissions. 35 figs., 5 tabs.

  10. Magnetic and electromagnetic properties of composites of iron oxide and Co-B alloy prepared by chemical reduction

    NASA Astrophysics Data System (ADS)

    Li, XueAi; Han, XiJiang; Du, YunChen; Xu, Ping

    2011-01-01

    Magnetic and electromagnetic properties were investigated on the composites of iron oxide and Co-B alloy, which were prepared by a modified chemical reduction method. The composites are characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDXA), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometry (VSM). The complex electromagnetic parameters (permittivity ɛr= ɛr'+j ɛr″ and permeability μr= μr'+j μr″) of paraffin mixed composite samples (paraffin:composites=1:1 in mass ratio) were measured in the frequency range 2-18 GHz by vector network analyzer. The measured real part ( ɛr') and imaginary part ( ɛr″) of the relative permittivity show two resonant peaks in the range of 2-18 GHz. The imaginary parts of relative permeability ( μr″) of all samples exhibited one broad resonant peak over the 2-8 GHz range. The μr″ of samples with higher molar ratio of Co to Fe (C and D) shows negative values within 13-18 GHz, which exhibit resonant and antiresonant permeabilities simultaneously. Calculation results indicated that the reflection loss values of the composites and paraffin wax mixtures are less than -10 dB with frequency width of about 6 GHz at the matching thickness.

  11. Synthesis and characterization of novel bactericidal Cu/HPMC BNCs using chemical reduction method for food packaging.

    PubMed

    Ebrahimiasl, Saeideh; Rajabpour, Ataollah

    2015-09-01

    In this research copper nanoparticles (Cu NPs) were incorporated in the biodegradable hydroxypropyl methylcellulose (HPMC) matrix using the simple and low cost chemical reduction method for application as food packaging material. The properties of Cu/HPMC bionanocomposites (BNCs) were studied as a function of the CuSO4 concentration. Surface morphology of the film was investigated by scanning electron microscopy. Mechanical analysis and water vapor barrier properties of HPMC/Cu nanocomposites were analyzed. It was observed that mechanical and water vapor barrier properties of the films were improved by the concentration of CuSO4. The antibacterial activity of HPMC/Cu thin films were evaluated based on the diameter of inhibition zone in a disk diffusion test against Gram positive bacteria, ie, Streptococus A., S. epidermidis, S.aureus , B.cereus and Gram negative bacteria, ie, E. coli, E. faecalis, Salmonella, P. aeruginosa using Mueller Hinton agar at different concentration of CuSO4. The results revealed a greater bactericidal effectiveness for nanocomposite films containing 5 % of CuSO4. Packages prepared from HPMC/Cu nanocomposite films were used for meat packaging. The films were filled with meat and then stored at 4 °C. Microbial stability of the meat was evaluated after 3, 7, 10 and 15 days of storage. The results showed that microbial growth rate significantly reduced as a result of using this nanocomposite packaging material.

  12. Influence of Sn on the magnetic ordering of Ni-Sn alloy synthesized using chemical reduction method

    NASA Astrophysics Data System (ADS)

    Dhanapal, K.; Narayanan, V.; Stephen, A.

    2016-05-01

    The Ni-Sn alloy was synthesized using borohydride assisted chemical reduction method. The composition of the synthesized alloy was determined using atomic absorption spectroscopy which revealed that the observed composition of Sn is high when compared to the initial composition. The ultrafine particles are clearly observed from field emission scanning electron microscope for all the sample. The X-ray diffraction measurement confirmed that the as-synthesized samples are of amorphous like nature while the samples annealed at 773 K showed crystalline nature. The Fourier transform infrared spectroscopy confirmed metallic bond stretching in the alloy samples. The crystallization and phase transition temperature was observed from differential scanning calorimetry. The shift in the crystallization temperature of Ni with increasing percentage of Sn was observed. The vibrating sample magnetometer was employed to understand the magnetic behavior of the Ni-Sn alloy. As-synthesized alloy samples showed paramagnetic nature while the annealed ones exhibit the soft ferromagnetic, antiferromagnetic and paramagnetic nature. The saturation magnetization value and magnetic ordering in the Ni-Sn alloys depend on the percentage of Sn present in the alloy.

  13. Application of integrated ozone and granular activated carbon for decolorization and chemical oxygen demand reduction of vinasse from alcohol distilleries.

    PubMed

    Hadavifar, Mojtaba; Younesi, Habibollah; Zinatizadeh, Ali Akbar; Mahdad, Faezeh; Li, Qin; Ghasemi, Zahra

    2016-04-01

    This study investigates the treatment of the distilleries vinasse using a hybrid process integrating ozone oxidation and granular activated carbons (GAC) in both batch and continuous operation mode. The batch-process studies have been carried out to optimize initial influent pH, GAC doses, the effect of the ozone (O3) and hydrogen peroxide (H2O2) concentrations on chemical oxygen demand (COD) and color removal of the distilleries vinasse. The continuous process was carried out on GAC and ozone treatment alone as well as the hybrid process comb both methods to investigate the synergism effectiveness of the two methods for distilleries vinasse COD reduction and color removal. In a continuous process, the Yan model described the experimental data better than the Thomas model. The efficiency of ozonation of the distilleries vinasse was more effective for color removal (74.4%) than COD removal (25%). O3/H2O2 process was not considerably more effective on COD and color removal. Moreover, O3/GAC process affected negatively on the removal efficiency by reducing COD and color from distilleries vinasse. The negative effect decreased by increasing pH value of the influent.

  14. A Facile Chemical Reduction of Graphene-Oxide Using p-Toluene Sulfonic Acid and Fabrication of Reduced Graphene-Oxide Film.

    PubMed

    Vengatesan, M R; Shen, Tian-Zi; Alagar, M; Song, Jang-Kun

    2016-01-01

    We report a cost effective and easy chemical reduction method for exfoliated individual graphene oxide (GO) and GO paper using p-toluene sulfonic acid (PTSA) under mild conditions. Raman spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), X-ray photon spectroscopy (XPS), thermo gravimetric analysis (TGA) and transmission electron microscopy (TEM) analysis were performed to investigate the quality of GO reduction. Data resulting from the spectral analysis suggest that the reduction method using PTSA is an efficient method to remove oxygen functionalities in the GO and also as an alternative to commonly used reducing agents. We also fabricated chemically reduced GO (RGO) film from GO film using this method. The RGO film exhibits an electrical conductivity of about 10587 Sm⁻¹. These results suggest that this method is very useful for the reduction of GO and GO film or paper using PTSA in a solution process for flexible electronics due to its facile, efficient and cost-effective features. PMID:27398462

  15. Wet chemical synthesis of intermetallic Pt3Zn nanocrystals via weak reduction reaction together with UPD process and their excellent electrocatalytic performances

    NASA Astrophysics Data System (ADS)

    Chen, Qiaoli; Zhang, Jiawei; Jia, Yanyan; Jiang, Zhiyuan; Xie, Zhaoxiong; Zheng, Lansun

    2014-05-01

    Platinum based alloy nanocrystals are promising catalysts for a variety of important practical process. However, it remains a great challenge to synthesize platinum-based intermetallic compound nanocrystals with well-defined surface structures. In this communication, taking the synthesis of concave cubic intermetallic Pt3Zn nanocrystals with {hk0} facets as an example, we proposed a new synthesis strategy for intermetallic compounds by reduction of noble metal precursors via a slow reduction process and reduction of transition metal ions via an underpotential deposition (UPD) process in wet chemical synthesis. The as-prepared intermetallic Pt3Zn nanocrystals exhibited superior CO poisoning tolerance and high electro-catalytic activity in both methanol and formic acid oxidation reactions in comparison with solid solution Pt3Zn nanocrystals and Pt/C.Platinum based alloy nanocrystals are promising catalysts for a variety of important practical process. However, it remains a great challenge to synthesize platinum-based intermetallic compound nanocrystals with well-defined surface structures. In this communication, taking the synthesis of concave cubic intermetallic Pt3Zn nanocrystals with {hk0} facets as an example, we proposed a new synthesis strategy for intermetallic compounds by reduction of noble metal precursors via a slow reduction process and reduction of transition metal ions via an underpotential deposition (UPD) process in wet chemical synthesis. The as-prepared intermetallic Pt3Zn nanocrystals exhibited superior CO poisoning tolerance and high electro-catalytic activity in both methanol and formic acid oxidation reactions in comparison with solid solution Pt3Zn nanocrystals and Pt/C. Electronic supplementary information (ESI) available: Additional characterization data. See DOI: 10.1039/c4nr00313f

  16. Chemical and biological reduction of Mn (III)-pyrophosphate complexes: Potential importance of dissolved Mn (III) as an environmental oxidant

    NASA Astrophysics Data System (ADS)

    Kostka, Joel E.; Luther, George W., III; Nealson, Kenneth H.

    1995-03-01

    Dissolved Mn (III) is a strong oxidant which could play an important role in the biogeochemistry of aquatic environments, but little is known about this form of Mn. Mn(III) was shown to form a stable complex with pyrophosphate which is easily measured by uv-vis spectrophotometry. The Mn(III)-pyrophosphate complex was produced at concentrations of 5 μM to 10 mM Mn at neutral pH. Inorganic electron donors, Fe(II) and sulfide, abiotically reduced Mn(III)-pyrophosphate in seconds with a stoichiometry of 1:1 and near 1:2 reductant:Mn (III), respectively. Shewanella putrefaciens strain MR-1 catalyzed the reduction of Mn(III)-pyrophosphate with formate or lactate as electron donors. Reduction of Mn(III) catalyzed by MR-1 was inhibited under aerobic conditions but only slightly under anaerobic conditions upon addition of the alternate electron acceptor, nitrate. MR-1 catalyzed reduction was also inhibited by metabolic inhibitors including formaldehyde, tetrachlorosalicylanilide (TCS), carbonyl cyanide m-chlorophenylhydrazone (CCCP), 2- n-heptyl-4-hydroxyquinoline N-oxide (HQNO), but not antimycin A. When formate or lactate served as electron donor for Mn(III) reduction, carbon oxidation to CO 2 was coupled to the respiration of Mn (III). Using the incorporation of 3H-leucine into the TCA-insoluble fraction of culture extracts, it was shown that Mn (III) reduction was coupled to protein synthesis in MR-1. These data indicate that Mn (III) complexes may be produced under conditions found in aquatic environments and that the reduction of Mn(III) can be coupled to the cycling of Fe, S, and C.

  17. Selective recovery of pure copper nanopowder from indium-tin-oxide etching wastewater by various wet chemical reduction process: Understanding their chemistry and comparisons of sustainable valorization processes.

    PubMed

    Swain, Basudev; Mishra, Chinmayee; Hong, Hyun Seon; Cho, Sung-Soo

    2016-05-01

    Sustainable valorization processes for selective recovery of pure copper nanopowder from Indium-Tin-Oxide (ITO) etching wastewater by various wet chemical reduction processes, their chemistry has been investigated and compared. After the indium recovery by solvent extraction from ITO etching wastewater, the same is also an environmental challenge, needs to be treated before disposal. After the indium recovery, ITO etching wastewater contains 6.11kg/m(3) of copper and 1.35kg/m(3) of aluminum, pH of the solution is very low converging to 0 and contain a significant amount of chlorine in the media. In this study, pure copper nanopowder was recovered using various reducing reagents by wet chemical reduction and characterized. Different reducing agents like a metallic, an inorganic acid and an organic acid were used to understand reduction behavior of copper in the presence of aluminum in a strong chloride medium of the ITO etching wastewater. The effect of a polymer surfactant Polyvinylpyrrolidone (PVP), which was included to prevent aggregation, to provide dispersion stability and control the size of copper nanopowder was investigated and compared. The developed copper nanopowder recovery techniques are techno-economical feasible processes for commercial production of copper nanopowder in the range of 100-500nm size from the reported facilities through a one-pot synthesis. By all the process reported pure copper nanopowder can be recovered with>99% efficiency. After the copper recovery, copper concentration in the wastewater reduced to acceptable limit recommended by WHO for wastewater disposal. The process is not only beneficial for recycling of copper, but also helps to address environment challenged posed by ITO etching wastewater. From a complex wastewater, synthesis of pure copper nanopowder using various wet chemical reduction route and their comparison is the novelty of this recovery process. PMID:26918838

  18. Selective recovery of pure copper nanopowder from indium-tin-oxide etching wastewater by various wet chemical reduction process: Understanding their chemistry and comparisons of sustainable valorization processes.

    PubMed

    Swain, Basudev; Mishra, Chinmayee; Hong, Hyun Seon; Cho, Sung-Soo

    2016-05-01

    Sustainable valorization processes for selective recovery of pure copper nanopowder from Indium-Tin-Oxide (ITO) etching wastewater by various wet chemical reduction processes, their chemistry has been investigated and compared. After the indium recovery by solvent extraction from ITO etching wastewater, the same is also an environmental challenge, needs to be treated before disposal. After the indium recovery, ITO etching wastewater contains 6.11kg/m(3) of copper and 1.35kg/m(3) of aluminum, pH of the solution is very low converging to 0 and contain a significant amount of chlorine in the media. In this study, pure copper nanopowder was recovered using various reducing reagents by wet chemical reduction and characterized. Different reducing agents like a metallic, an inorganic acid and an organic acid were used to understand reduction behavior of copper in the presence of aluminum in a strong chloride medium of the ITO etching wastewater. The effect of a polymer surfactant Polyvinylpyrrolidone (PVP), which was included to prevent aggregation, to provide dispersion stability and control the size of copper nanopowder was investigated and compared. The developed copper nanopowder recovery techniques are techno-economical feasible processes for commercial production of copper nanopowder in the range of 100-500nm size from the reported facilities through a one-pot synthesis. By all the process reported pure copper nanopowder can be recovered with>99% efficiency. After the copper recovery, copper concentration in the wastewater reduced to acceptable limit recommended by WHO for wastewater disposal. The process is not only beneficial for recycling of copper, but also helps to address environment challenged posed by ITO etching wastewater. From a complex wastewater, synthesis of pure copper nanopowder using various wet chemical reduction route and their comparison is the novelty of this recovery process.

  19. Sulfidation of Nano Zerovalent Iron (nZVI) for Improved Selectivity During In-Situ Chemical Reduction (ISCR).

    PubMed

    Fan, Dimin; O'Brien Johnson, Graham; Tratnyek, Paul G; Johnson, Richard L

    2016-09-01

    The high reactivity of nano zerovalent iron (nZVI) leads to inefficient treatment due to competition with various natural reductant demand (NRD) processes, especially the reduction of water to hydrogen. Here we show that this limitation can be alleviated by sulfidation (i.e., modification by reducing sulfur compounds). nZVI synthesized on carboxylmethylcelluose (CMC-nZVI) was sulfidated with either sulfide or dithionite. The reactivity of the resulting materials was examined with three complementary assays: (i) direct measurement of hydrogen production, (ii) reduction of a colorimetric redox probe (indigo disulfonate, I2S), and (iii) dechlorination of trichloroethylene (TCE). The results indicate that sulfidation at S/Fe molar ratios of ≥0.3, effectively eliminates reaction with water, but retains significant reactivity with TCE. However, sulfidation with sulfide leaves most of the nZVI as Fe(0), whereas dithionite converts a majority of the nZVI to FeS (thus consuming much of the reducing capacity originally provided by the Fe(0)). Simplified numerical models show that the reduction kinetics of I2S and TCE are mainly dependent on the initial reducing equivalents and that the TCE reduction rate is affected by the aging of FeS. Overall, the results suggest that pretreatment of nZVI with reducing sulfur compounds could result in substantial improvement in nZVI selectivity. PMID:27454131

  20. Waste Reduction Assistance Program (WRAP) on-site consultation audit report: Plastic bottle making/chemical manufacturing

    SciTech Connect

    1988-06-01

    The information contained herein is intended to be general guidance for the facility described in the report and the industry as a whole. It is the product of approximately 6 to 8 hours of on-site consultation with the facility owner. The focus of the report is waste management and waste reduction, not regulatory compliance. Regulatory issues mentioned are discussed only insofar as they impinge on management issues related to hazardous waste management and waste reduction, and are not part of a comprehensive discussion about all pertinent regulation requirements.

  1. Direct deposition of gold nanoplates and porous platinum on substrates through solvent-free chemical reduction of metal precursors with ethylene glycol vapor.

    PubMed

    Cho, Swee Jen; Mei, Xiaoguang; Ouyang, Jianyong

    2012-12-01

    Deposition of nanostructured metals on substrates is important for the fundamental study and practical application, such as in optics and catalysis. In this paper, we report the deposition of gold (Au) nanoplates and porous platinum (Pt) structures on substrates through solvent-free chemical reductions of chloroauric acid (HAuCl(4)) and chloroplatinic acid (H(2)PtCl(6)) with ethylene glycol (EG) vapor at temperatures below 200 °C. The process includes two steps. The first step is the formation of a thin layer of a metal precursor on substrates by coating solution of a metal precursor. The thin metal precursor layer is subsequently dried by annealing. The second step is the chemical reduction of the metal precursor with EG vapor at 160 or 180 °C in the absence of solvent. Both the Au and Pt nanostructures deposited by this method have good adhesion to substrates, but they have different morphologies. The Au nanostructures appear as separate two-dimensional islands on the substrates, and up to 70% of them can be triangular nanoplates with the (111) crystal plane as the basal plane. In contrast, the reduction of H(2)PtCl(6) gives rise to a 3-dimensional porous Pt structure on substrates. The different morphologies of nanostructured Au and Pt are tentatively related to the different surface energies of Au and Pt.

  2. Functional Fixedness and Functional Reduction as Common Sense Reasonings in Chemical Equilibrium and in Geometry and Polarity of Molecules.

    ERIC Educational Resources Information Center

    Furio, C.; Calatayud, M. L.; Barcenas, S. L.; Padilla, O. M.

    2000-01-01

    Focuses on learning difficulties in procedural knowledge, and assesses the procedural difficulties of grade 12 and first- and third-year university students based on common sense reasoning in two areas of chemistry--chemical equilibrium and geometry, and polarity of molecules. (Contains 55 references.) (Author/YDS)

  3. Coupling of chemical kinetics, gas dynamics, and charged particle kinetics models for the analysis of NO reduction from flue gases

    SciTech Connect

    Eichwald, O.; Yousfi, M.; Hennad, A.; Benabdessadok, M.D.

    1997-11-01

    A chemical kinetics model is developed to analyze the time evolution of the different main species involved in a flue gas initially stressed by a pulsed corona discharge at the atmospheric pressure and including N{sub 2}, O{sub 2}, H{sub 2}O, and CO{sub 2} with a few ppm of NO. The present chemical kinetics model is coupled to a gas dynamics model used to analyze the radial expansion of the gas in the ionized channel created during the discharge phase. It is also meant to analyze the gas heating due to the Joule effect. This chemical kinetics model is also coupled to charged particle kinetics models based on a Boltzmann equation model to calculate the electron-molecule reaction coefficients in the flue gas and on a Monte Carlo code to estimate the energy and momentum transfer terms relative to ion-molecule collisions which are the input data for the gas dynamics model. It is shown, in particular, that the evolution of the radicals and the oxides is substantially affected by the gas temperature rise (from the initial value of 300 K up to 750 K near the anode) thus emphasizing the present coupling between gas dynamics, charged particle, and chemical kinetics models. {copyright} {ital 1997 American Institute of Physics.}

  4. Coupling of chemical kinetics, gas dynamics, and charged particle kinetics models for the analysis of NO reduction from flue gases

    NASA Astrophysics Data System (ADS)

    Eichwald, O.; Yousfi, M.; Hennad, A.; Benabdessadok, M. D.

    1997-11-01

    A chemical kinetics model is developed to analyze the time evolution of the different main species involved in a flue gas initially stressed by a pulsed corona discharge at the atmospheric pressure and including N2, O2, H2O, and CO2 with a few ppm of NO. The present chemical kinetics model is coupled to a gas dynamics model used to analyze the radial expansion of the gas in the ionized channel created during the discharge phase. It is also meant to analyze the gas heating due to the Joule effect. This chemical kinetics model is also coupled to charged particle kinetics models based on a Boltzmann equation model to calculate the electron-molecule reaction coefficients in the flue gas and on a Monte Carlo code to estimate the energy and momentum transfer terms relative to ion-molecule collisions which are the input data for the gas dynamics model. It is shown, in particular, that the evolution of the radicals and the oxides is substantially affected by the gas temperature rise (from the initial value of 300 K up to 750 K near the anode) thus emphasizing the present coupling between gas dynamics, charged particle, and chemical kinetics models.

  5. Preparation of Pt-Ru@ polypyrrole-MWNT catalysts by gamma-irradiation and chemical reduction and their adsorption capacity for CO.

    PubMed

    Bae, Hyoung-Bong; Oh, Sang-Hyub; Woo, Jin-Chun; Choi, Seong-Ho

    2010-10-01

    With the objective to prepare electrocatalysts with high efficiency, the Pt-Ru@PPy-MWNT catalysts were prepared by different approaches. First, the polypyrrole (PPy) as anchoring materials was coated on the surface of multi walled carbon nanotubes (MWNT) by in situ polymerization. Subsequently, Pt-Ru nanoparticles were deposited onto PPy-MWNT composite by different methods like the reduction of metal ions by gamma-irradiation and chemical reduction using formaldehyde as reducing agent assisted with stirring of magnetic bar, and assisted with microwave irradiation, and assisted with ultrasonic irradiation, in order to prepare electrocatalyst for fuel cell. The catalytic efficiency of Pt-Ru@PPy-MWNT catalyst was examined for CO stripping. PMID:21137821

  6. On the Theory of Oxidation-Reduction Reactions Involving Electron Transfer. V. Comparison and Properties of Electrochemical and Chemical Rate Constants

    DOE R&D Accomplishments Database

    Marcus, R. A.

    1962-01-01

    Using a theory of electron transfers which takes cognizance of reorganization of the medium outside the inner coordination shell and of changes of bond lengths inside it, relations between electrochemical and related chemical rate constants are deduced and compared with the experimental data. A correlation is found, without the use of arbitrary parameters. Effects of weak complexes with added electrolytes are included under specified conditions. The deductions offer a way of coordinating a variety of data in the two fields, internally as well as with each those in another. For example, the rate of oxidation or reduction of a series of related reactants by one reagent is correlated with that of another and with that of the corresponding electrochemical oxidation-reduction reaction, under certain specified conditions. These correlations may also provide a test for distinguishing an electron from an atom transfer mechanism. (auth)

  7. Single-step treatment of 2,4-dinitrotoluene via zero-valent metal reduction and chemical oxidation.

    PubMed

    Thomas, J Mathew; Hernandez, Rafael; Kuo, Chiang-Hai

    2008-06-30

    Many nitroaromatic compounds (NACs) are considered toxic and potential carcinogens. The purpose of this study was to develop an integrated reductive/oxidative process for treating NACs contaminated waters. The process consists of the combination of zero-valent iron and an ozonation based treatment technique. Corrosion promoters are added to the contaminated water to minimize passivation of the metallic species. Water contaminated with 2,4-dinitrotoluene (DNT) was treated with the integrated process using a recirculated batch reactor. It was demonstrated that addition of corrosion promoters to the contaminated water enhances the reduction of 2,4-DNT with zero-valent iron. The addition of corrosion promoters resulted in 62% decrease in 2,4-DNT concentration to 2,4-diaminotoluene. The data shows that iron reduced the 2,4-DNT and ozone oxidized these products resulting in a 73% removal of TOC and a 96% decrease in 2,4-DNT concentration.

  8. Reduction of Large Detailed Chemical Kinetic Mechanisms for Autoignition Using Joint Analyses of Reaction Rates and Sensitivities

    SciTech Connect

    Saylam, A; Ribaucour, M; Pitz, W J; Minetti, R

    2006-11-29

    A new technique of reduction of detailed mechanisms for autoignition, which is based on two analysis methods is described. An analysis of reaction rates is coupled to an analysis of reaction sensitivity for the detection of redundant reactions. Thresholds associated with the two analyses have a great influence on the size and efficiency of the reduced mechanism. Rules of selection of the thresholds are defined. The reduction technique has been successfully applied to detailed autoignition mechanisms of two reference hydrocarbons: n-heptane and iso-octane. The efficiency of the technique and the ability of the reduced mechanisms to reproduce well the results generated by the full mechanism are discussed. A speedup of calculations by a factor of 5.9 for n-heptane mechanism and by a factor of 16.7 for iso-octane mechanism is obtained without losing accuracy of the prediction of autoignition delay times and concentrations of intermediate species.

  9. One-pot wet-chemical co-reduction synthesis of bimetallic gold-platinum nanochains supported on reduced graphene oxide with enhanced electrocatalytic activity

    NASA Astrophysics Data System (ADS)

    Chen, De-Jun; Zhang, Qian-Li; Feng, Jin-Xia; Ju, Ke-Jian; Wang, Ai-Jun; Wei, Jie; Feng, Jiu-Ju

    2015-08-01

    In this work, a simple, rapid and facile one-pot wet-chemical co-reduction method is developed for synthesis of bimetallic Au-Pt alloyed nanochains supported on reduced graphene oxide (Au-Pt NCs/RGO), in which caffeine is acted as a capping agent and a structure-directing agent, while no any seed, template, surfactant or polymer involved. The as-prepared nanocomposites display enlarged electrochemical active surface area, significantly enhanced catalytic activity and better stability for methanol and ethylene glycol oxidation, compared with commercial Pt-C (Pt 50 wt%), PtRu-C (Pt 30 wt% and Ru 15 wt%) and Pt black.

  10. Interplay between grain size reduction, chemical reaction, and shear localization in lower crustal rocks: a case study from Archaean Bundelkhand Craton, North-Central India

    NASA Astrophysics Data System (ADS)

    Bhandari, Ankit; Nasipuri, Pritam; Saha, Lopamudra; Pati, Jayanta Kumar; Sarkar, Saheli; Purohit, Rohan

    2016-04-01

    Weakening of the rocks is pronounced during the formation of shear zone. Crustal scale shear zones at the plate boundary develop due to grain size reduction, either by mechanical breakdown of minerals or by the development of new minerals due to change in pressure (P) - temperature (T) conditions. In either of the mechanisms for grain size reduction, the Gibb's free energy of the system should be minimum in value to stabilize the mineral.In this contribution, we have studied the deformation mechanism and P-T conditions from acrustal scale shear zone, in the North Central Part of Archaean Bundelkhand Craton. In the Archaean Buldelkhand craton, tens of kilometre wide E-W trending shear zone developed in the sodic-potassic granite. The undeformed rock (protolith) is characterized by euhedral to subhedral sodic feldspar (XAb =0.80) and subordinate quartz, whereas the deformed rock is characterized by the development of extremely deformed feldspar and quartz associated with chlorite. The onset of the strain localization and shear zone formation in the proto-mylonite has been accompanied by developing brittle fractures in the euhedral feldspar grains. In contrast to the brittle deformation in feldspar, quartz grains are characterized by development of small bulges around the grain boundary. Chlorite develops at the fractures in the feldspar that are indicative of fluid infiltration in the proto-mylonite.In the extremely deformed samples (ultramylonite) grain size reduction occurs by bulging recrystallization in quartz. Flow stress obtained from grain size analysis of quartz indicates that the palaeo-stress varies from ~44-46 MPa in proto-mylonite to ~ 61-63 MPa in Ultra-mylonite. Mineral chemical analysis of undeformed feldspar grains in the protolith and mylonite indicate significant changes in the chemical composition that leads to minimum Gibbs energy. Also the presence of chlorite indicates hydration reaction, which has reduced the chemical energy of the system

  11. Comparative analysis on the effects of diesel particulate filter and selective catalytic reduction systems on a wide spectrum of chemical species emissions.

    PubMed

    Liu, Z Gerald; Berg, Devin R; Swor, Thaddeus A; Schauer, James J

    2008-08-15

    Two methods, diesel particulate filter (DPF) and selective catalytic reduction (SCR) systems,for controlling diesel emissions have become widely used, either independently or together, for meeting increasingly stringent emissions regulations worldwide. Each of these systems is designed for the reduction of primary pollutant emissions including particulate matter (PM) for DPF and nitrogen oxides (NOx) for SCR. However, there have been growing concerns regarding the secondary reactions that these aftertreatment systems may promote, involving unregulated species emissions. This study was performed to gain an understanding of the effects that these aftertreatment systems may have on the emission levels of a wide spectrum of chemical species found in diesel engine exhaust. Samples were extracted using a source dilution sampling system designed to collect exhaust samples representative of real-world emissions. Testing was conducted on a heavy-duty diesel engine with no aftertreatment devices to establish a baseline measurement and also on the same engine equipped first with a DPF system and then a SCR system. Each of the samples was analyzed for a wide variety of chemical species, including elemental and organic carbon, metals, ions, n-alkanes, aldehydes, and polycyclic aromatic hydrocarbons, in addition to the primary pollutants, due to the potential risks they pose to the environment and public health. The results show that the DPF and SCR systems were capable of substantially reducing PM and NOx emissions, respectively. Further, each of the systems significantly reduced the emission levels of the unregulated chemical species, while the notable formation of new chemical species was not observed. It is expected that a combination of the two systems in some future engine applications would reduce both primary and secondary emissions significantly.

  12. Reduction on the anaerobic biological activity inhibition caused by heavy metals and sulphates in effluents through chemical precipitation with soda and lime.

    PubMed

    Alves, L de Carvalho; Cammarota, M C; De França, F P

    2006-12-01

    The School of Chemistry Environmental Technology Laboratory generates 43.4 1 of effluent with low pH (0.7) and high contents of COD (1908 mgO2 l(-1)), phenol (132.1 mg l(-1)), sulfate (36700 mg l(-1)) and heavy metals (28.2 mg Hg l(-1); 82.1 mg Cr(total) l(-1); 30.8 mg Cu l(-1); 57.4 mg Fe(total) l(-1); 16.2 mg Al l(-1)) weekly. These data show that this effluent presents high toxicity for biological treatment, with a physical-chemical step being necessary before a biological step. Preliminary studies showed that the most toxic constituents of the effluent were sulfate, phenol and total chromium. In this work, a chemical precipitation step with sodium hydroxide or lime was evaluated for the toxicity reduction on anaerobic microbial consortium. These experiments were carried out with increasing concentrations of alkalis in the effluent in order to obtain pH initial values of 8-12. Similar results were obtained for COD (15-28%), turbidity (95-98%), phenol (13-24%) and total chromium (99.8-99.9%) removals in each condition studied with soda or lime. Sulfate was only removed by precipitation with lime, obtaining reductions from 84 to 88%. The toxicity on the anaerobic sludge was studied employing specific methanogenic activity (SMA) analysis of raw and treated effluent (after chemical precipitation step). The SMA experiments showed that chemical precipitation at pH 8 reduces the toxic effect of the effluent on anaerobic microbial consortium three times (with soda) and thirteen times (with lime). These results indicate that precipitation with lime is more efficient at toxicity removal, however the produced sludge volume is around two times higher than that produced with soda.

  13. Reduction on the anaerobic biological activity inhibition caused by heavy metals and sulphates in effluents through chemical precipitation with soda and lime.

    PubMed

    Alves, L de Carvalho; Cammarota, M C; De França, F P

    2006-12-01

    The School of Chemistry Environmental Technology Laboratory generates 43.4 1 of effluent with low pH (0.7) and high contents of COD (1908 mgO2 l(-1)), phenol (132.1 mg l(-1)), sulfate (36700 mg l(-1)) and heavy metals (28.2 mg Hg l(-1); 82.1 mg Cr(total) l(-1); 30.8 mg Cu l(-1); 57.4 mg Fe(total) l(-1); 16.2 mg Al l(-1)) weekly. These data show that this effluent presents high toxicity for biological treatment, with a physical-chemical step being necessary before a biological step. Preliminary studies showed that the most toxic constituents of the effluent were sulfate, phenol and total chromium. In this work, a chemical precipitation step with sodium hydroxide or lime was evaluated for the toxicity reduction on anaerobic microbial consortium. These experiments were carried out with increasing concentrations of alkalis in the effluent in order to obtain pH initial values of 8-12. Similar results were obtained for COD (15-28%), turbidity (95-98%), phenol (13-24%) and total chromium (99.8-99.9%) removals in each condition studied with soda or lime. Sulfate was only removed by precipitation with lime, obtaining reductions from 84 to 88%. The toxicity on the anaerobic sludge was studied employing specific methanogenic activity (SMA) analysis of raw and treated effluent (after chemical precipitation step). The SMA experiments showed that chemical precipitation at pH 8 reduces the toxic effect of the effluent on anaerobic microbial consortium three times (with soda) and thirteen times (with lime). These results indicate that precipitation with lime is more efficient at toxicity removal, however the produced sludge volume is around two times higher than that produced with soda. PMID:17285944

  14. Solutia: Massachusetts Chemical Manufacturer Uses SECURE Methodology to Identify Potential Reductions in Utility and Process Energy Consumption

    SciTech Connect

    2005-07-01

    This case study prepared for the U.S. Department of Energy's Industrial Technologies Program describes a plant-wide energy assessment conducted at the Solutia Inc. chemical production facility in Springfield, Massachusetts. Solutia manufactures polymers, intermediates, and chemicals for a variety of products. The assessment focused on finding ways to reduce the plant's use of steam, electricity, compressed air, and water. If the company were to implement all the recommendations that came out of the assessment, its total annual energy savings could be about 9.6 million kWh for electricity and more than 338,000 MBtu for natural gas. Annual cost savings could amount to nearly $3.3 million.

  15. Low-Temperature Chemical Vapor Deposition Synthesis of Pt-Co Alloyed Nanoparticles with Enhanced Oxygen Reduction Reaction Catalysis.

    PubMed

    Choi, Dong Sung; Robertson, Alex W; Warner, Jamie H; Kim, Sang Ouk; Kim, Heeyeon

    2016-09-01

    Novel Pt-Co alloyed nanocatalysts are generated via chemical vapor deposition-assisted facile one-pot synthesis. The method guarantees highly monodisperse Pt-Co alloy nanoparticles with precise control of metallic compositions within 1 at%. A significant features is that a perfectly alloyed single-crystal structure is obtained at temperatures as low as 500 °C, which is much lower than conventional alloying temperatures.

  16. Sorption and toxicity reduction of pharmaceutically active compounds and endocrine disrupting chemicals in the presence of colloidal humic acid.

    PubMed

    Kim, Injeong; Kim, Hyo-Dong; Jeong, Tae-Yong; Kim, Sang Don

    2016-01-01

    This study investigated the toxicity changes and sorption of pharmaceuticals and endocrine disrupters in the presence of humic acid (HA). For the sorption experiment, a dead end filtration (DEF) system was used to separate bound and free-form target compounds. An algae growth inhibition test and E-screen assay were conducted to estimate the toxic effect of pharmaceutically active compounds (PhACs) and endocrine disrupting chemicals (EDCs), respectively. The permeate concentration was confirmed using liquid chromatography-mass spectrometry. In the sorption test, we observed significant sorption of PhACs and EDCs on colloidal HA, except for sulfamethoxazole (SMX). The values of log KCOC derived from DEF determinations ranged from 4.40 to 5.03. The removal efficiency varied with the HA concentration and the target chemical properties. Tetracycline and 4-octylphenol showed the highest sorption or removal efficiency (≈50%), even at 5 mg C/L HA. The algal growth inhibition of PhACs and the estrogenic effects of EDCs were significantly decreased in proportion to HA concentrations, except for SMX. In addition, the chemical analysis results showed a positive relationship with the bioassay results. Consequently, the sorption of PhACs and EDCs onto colloidal HA should be emphasized in natural environments because it significantly reduces bioavailable concentrations and toxicity to aquatic organisms. PMID:27533865

  17. Three-dimensional assemblies of graphene prepared by a novel chemical reduction-induced self-assembly method.

    PubMed

    Zhang, Lianbin; Chen, Guoying; Hedhili, Mohamed Nejib; Zhang, Hongnan; Wang, Peng

    2012-11-21

    In this study, three-dimensional (3D) graphene assemblies are prepared from graphene oxide (GO) by a facile in situ reduction-assembly method, using a novel, low-cost, and environment-friendly reducing medium which is a combination of oxalic acid (OA) and sodium iodide (NaI). It is demonstrated that the combination of a reducing acid, OA, and NaI is indispensable for effective reduction of GO in the current study and this unique combination (1) allows for tunable control over the volume of the thus-prepared graphene assemblies and (2) enables 3D graphene assemblies to be prepared from the GO suspension with a wide range of concentrations (0.1 to 4.5 mg mL(-1)). To the best of our knowledge, the GO concentration of 0.1 mg mL(-1) is the lowest GO concentration ever reported for preparation of 3D graphene assemblies. The thus-prepared 3D graphene assemblies exhibit low density, highly porous structures, and electrically conducting properties. As a proof of concept, we show that by infiltrating a responsive polymer of polydimethylsiloxane (PDMS) into the as-resulted 3D conducting network of graphene, a conducting composite is obtained, which can be used as a sensing device for differentiating organic solvents with different polarity.

  18. Photoelectrocatalytic reduction of CO2 into chemicals using Pt-modified reduced graphene oxide combined with Pt-modified TiO2 nanotubes.

    PubMed

    Cheng, Jun; Zhang, Meng; Wu, Gai; Wang, Xin; Zhou, Junhu; Cen, Kefa

    2014-06-17

    The photoelectrocatalytic (PEC) reduction of CO2 into high-value chemicals is beneficial in alleviating global warming and advancing a low-carbon economy. In this work, Pt-modified reduced graphene oxide (Pt-RGO) and Pt-modified TiO2 nanotubes (Pt-TNT) were combined as cathode and photoanode catalysts, respectively, to form a PEC reactor for converting CO2 into valuable chemicals. XRD, XPS, TEM, AFM, and SEM were employed to characterize the microstructures of the Pt-RGO and Pt-TNT catalysts. Reduction products, such as C2H5OH and CH3COOH, were obtained from CO2 under band gap illumination and biased voltage. A combined liquid product generation rate (CH3OH, C2H5OH, HCOOH, and CH3COOH) of approximately 600 nmol/(h·cm(2)) was observed. Carbon atom conversion rate reached 1,130 nmol/(h·cm(2)), which were much higher than those achieved using Pt-modified carbon nanotubes and platinum carbon as cathode catalysts. PMID:24846604

  19. Capacity of a newly isolated fungus Pleurotus eryngii from Tunceli, Ovacik for chemical oxygen demand reduction and biodecolorization of Azo-Dye Congo Red.

    PubMed

    Yildirim, N; Gonen, U

    2015-06-07

    Biodecolorization of Congo red dye in both agar—plate and agitated liquid culture mediums by newly isolated white rot fungus Pleurotus eryngii has been studied. This fungus isolated from Tunceli—Ovacik province of Turkey. We have also examined the chemical oxygen demand reduction after decolorization under agitated liquid culture medium. For agar plate screening the decolorization capacity of P. eryngii, growth and decolorization halos were determined on saboroud dextrose agar (SDA) plates containing 0.05, 0.1, 0.5, 1 and 2 g/l of Congo red. P. eryngii showed certain decolorization capacities and was able to decolorize all studied concentrations of Congo red, but not to the same extent. Our results indicated that the new isolate P. eryngii had maximum decolorization (87% at 100 mg/l initial dye concentration) and chemical oxygen demand reduction (82% at 25 mg/l initial dye concentration) activities after 7 days under agitated submerged culture conditions. This new isolate could be an effective bioremediation tool for treatment of Congo red containing textile wastewater.

  20. Evaluation of sludge reduction by an environmentally friendly chemical uncoupler in a pilot-scale anaerobic/anoxic/oxic process.

    PubMed

    Guo, Xuesong; Yang, Jianming; Liang, Yuan; Liu, Junxin; Xiao, Benyi

    2014-03-01

    An environmentally friendly chemical, tetrakis(hydroxymethyl)phosphonium sulfate (THPS), was used as a metabolic uncoupler to reduce sludge production in a pilot-scale anaerobic/anoxic/oxic process. The results show that the addition of THPS (1.08-1.86 mL/m(3) influent) in the sludge return section could reduce waste activated sludge by about 22.5 %, and decrease the sludge yield by about 14.7 % at the end of a run. At the same time, the addition of THPS slightly lowered the removal of chemical oxygen demand (COD), soluble COD and NH4 (+)-N, and slightly improved removal of total nitrogen. The effects of THPS addition on two characteristics of activated sludge in oxic tank are discussed in detail and the results suggest that the settleability of sludge was reduced by addition of THPS, while the specific oxygen uptake rate was increased. Molecular biology analysis shows that the addition of THPS had little effect on the microbial communities of sludge.

  1. Three-dimensional assemblies of graphene prepared by a novel chemical reduction-induced self-assembly method

    NASA Astrophysics Data System (ADS)

    Zhang, Lianbin; Chen, Guoying; Hedhili, Mohamed Nejib; Zhang, Hongnan; Wang, Peng

    2012-10-01

    In this study, three-dimensional (3D) graphene assemblies are prepared from graphene oxide (GO) by a facile in situ reduction-assembly method, using a novel, low-cost, and environment-friendly reducing medium which is a combination of oxalic acid (OA) and sodium iodide (NaI). It is demonstrated that the combination of a reducing acid, OA, and NaI is indispensable for effective reduction of GO in the current study and this unique combination (1) allows for tunable control over the volume of the thus-prepared graphene assemblies and (2) enables 3D graphene assemblies to be prepared from the GO suspension with a wide range of concentrations (0.1 to 4.5 mg mL-1). To the best of our knowledge, the GO concentration of 0.1 mg mL-1 is the lowest GO concentration ever reported for preparation of 3D graphene assemblies. The thus-prepared 3D graphene assemblies exhibit low density, highly porous structures, and electrically conducting properties. As a proof of concept, we show that by infiltrating a responsive polymer of polydimethylsiloxane (PDMS) into the as-resulted 3D conducting network of graphene, a conducting composite is obtained, which can be used as a sensing device for differentiating organic solvents with different polarity.In this study, three-dimensional (3D) graphene assemblies are prepared from graphene oxide (GO) by a facile in situ reduction-assembly method, using a novel, low-cost, and environment-friendly reducing medium which is a combination of oxalic acid (OA) and sodium iodide (NaI). It is demonstrated that the combination of a reducing acid, OA, and NaI is indispensable for effective reduction of GO in the current study and this unique combination (1) allows for tunable control over the volume of the thus-prepared graphene assemblies and (2) enables 3D graphene assemblies to be prepared from the GO suspension with a wide range of concentrations (0.1 to 4.5 mg mL-1). To the best of our knowledge, the GO concentration of 0.1 mg mL-1 is the lowest GO

  2. Chemical exposure reduction: Factors impacting on South African herbicide sprayers' personal protective equipment compliance and high risk work practices.

    PubMed

    Andrade-Rivas, Federico; Rother, Hanna-Andrea

    2015-10-01

    The high exposure risks of workers to herbicides in low- and middle-income countries is an important public health concern because of the potential resulting negative impacts on workers' health. This study investigated workers' personal protective equipment (PPE) compliance as a risk mitigation measure; particularly workers who apply herbicides for Working for Water (WfW) - a South African invasive alien vegetation control programme. The study aim was to understand workers' low PPE compliance by analysing their risk perceptions of herbicide use, working conditions and socio-cultural context. Research methods included ethnographic observations, informal interviews, visual media, questionnaires and a focus group. Study results indicated that low PPE compliance persists despite workers' awareness of herbicide exposure risks and as a result of the influence from workers' socio-cultural context (i.e. gender dynamics and social status), herbicide risk perceptions and working conditions (i.e. environmental and logistical). Interestingly, teams comprised of mostly women had the highest compliance rate. These findings highlighted that given the complexity of PPE compliance, especially in countries with several economic and social constraints, exposure reduction interventions should not rely solely on PPE use promotion. Instead, other control strategies requiring less worker input for effectiveness should be implemented, such as elimination and substitution of highly hazardous pesticides, and altering application methods. PMID:26093240

  3. Chemical exposure reduction: Factors impacting on South African herbicide sprayers' personal protective equipment compliance and high risk work practices.

    PubMed

    Andrade-Rivas, Federico; Rother, Hanna-Andrea

    2015-10-01

    The high exposure risks of workers to herbicides in low- and middle-income countries is an important public health concern because of the potential resulting negative impacts on workers' health. This study investigated workers' personal protective equipment (PPE) compliance as a risk mitigation measure; particularly workers who apply herbicides for Working for Water (WfW) - a South African invasive alien vegetation control programme. The study aim was to understand workers' low PPE compliance by analysing their risk perceptions of herbicide use, working conditions and socio-cultural context. Research methods included ethnographic observations, informal interviews, visual media, questionnaires and a focus group. Study results indicated that low PPE compliance persists despite workers' awareness of herbicide exposure risks and as a result of the influence from workers' socio-cultural context (i.e. gender dynamics and social status), herbicide risk perceptions and working conditions (i.e. environmental and logistical). Interestingly, teams comprised of mostly women had the highest compliance rate. These findings highlighted that given the complexity of PPE compliance, especially in countries with several economic and social constraints, exposure reduction interventions should not rely solely on PPE use promotion. Instead, other control strategies requiring less worker input for effectiveness should be implemented, such as elimination and substitution of highly hazardous pesticides, and altering application methods.

  4. P, T-dependence of the thermoelectric power of minerals; relations to chemical differentiation, hydration, oxidation and reduction

    NASA Astrophysics Data System (ADS)

    Schloessin, H. H.

    1982-07-01

    The thermoelectric power (T.E.P.) or Seebeck effect of minerals is best characterized by the fact that a great many of the Earth's important minerals are semiconducting oxides. Outside the very active research area concerned with oxide semiconductors there have been few determinations of the T.E.P. of minerals, let alone their P, T-dependence. Most minerals have low electrical conductivities and relatively high thermal conductivities, and despite very high Seebeck voltages, are thus generally rather inefficient T.E.P. generators. Measurements of the T.E.P. tie in well with studies of the electrical conductivity, thermal conductivity, optical absorption, and diffusion. They provide significant information on the charge carrier concentrations, type of conduction mechanism, band structure, and phonon scattering. Junctions capable of generating T.E.P. include those between materials of different chemical composition, different content and concentration of impurities and defects, different crystal structure or orientation, different states of stress and strain, and reactive junctions or chains of junctions. Considering the local balance of flux of heat and other forms of energy through any of the conduction channels we may visualize as traversing the minerals in the mantle, surely, the conduction channels must involve all of the different types of heterogeneous junctions between minerals. We are, therefore, interested to investigate to what extent, in channels or media subjected to gradients of temperature, electric potential, concentration of chemical constituents and stress or strain, the heat flux density is not identical with the total energy flux density. Measurements of the Seebeck coefficient ( S = d E/d T) and preliminary interpretations are discussed with reference to: (1) a simple oxide relative to Pt (corundum); (2) a complex oxide relative to Pt (garnet, almandite); (3) a couple formed of two oxides (corundum-almandite); (4) a couple formed of two minerals

  5. Reduction of carbon dioxide gas formation at the anode of a direct methanol fuel cell using chemically enhanced solubility

    NASA Astrophysics Data System (ADS)

    Lundin, Michael D.; McCready, Mark J.

    The production of CO 2 gas at the DMFC anode leads to dramatic increases in pumping power requirements and reduced power output because of mass transfer limitations as bubble trains form in the channels of larger stacks. Experimental observations taken in a 5 cm 2 DMFC test cell operated at 60 °C, 1 atm, and with a methanol/water fuel flow rates of 5-10 cm 3 min -1 indicate that the rate of bubble formation can be reduced by increasing the fuel flow because more liquid is available for the CO 2 to dissolve in. Further observations indicate that KOH and LiOH added to the fuel eliminates CO 2 gas formation in situ at low concentrations because of the greatly increased solubility that results. A mathematical model for the volumetric rate of CO 2 gas production that includes effects of temperature and solubility is developed and extended to include the effects of hydroxide ions in solution. The model is used to predict the onset location of gas formation in the flow field as well as the void fraction at any point in the flow field. Predictions from the model agree very well with our experiments. Model predictions explain differences in the initial location of bubble formation for fuel solutions pre-saturated with CO 2 as opposed to CO 2-free solutions. Experiments with KOH and LiOH added to fuel solutions confirm the validity of the model extension that includes solubility that is enhanced by chemical reaction. Experiments with LiOH, KOH, and ammonium hydroxide show that the long-term durability of standard Pt-Ru/Nafion ®/Pt membrane electrode assemblies is compromised because of the presence of lithium, potassium, and ammonium cations that interact with the Nafion ® membrane and result in increasing the ohmic limitations of the polymer electrolyte membrane. Experiments with Ca(OH) 2, while reducing gas formation, precipitate the product CaCO 3 out of solution too rapidly for downstream filtering, blocking channels in the flow field.

  6. Removal of pollutants and reduction of bio-toxicity in a full scale chemical coagulation and reverse osmosis leachate treatment system.

    PubMed

    Theepharaksapan, S; Chiemchaisri, C; Chiemchaisri, W; Yamamoto, K

    2011-05-01

    Removals of pollutants and toxic organic compounds and reduction in bio-toxicity of leachate along an operating full-scale leachate treatment system utilizing chemical coagulation, sand filtration, microfiltration (MF) and reverse osmosis (RO) membrane were evaluated. High pollutant removals were achieved mainly by coagulation and sand filtration. Major toxic organic pollutants, i.e. DEHP, DBP and bisphenol A were removed by 100%, 99.6% and 98.0%. Acute toxicity test using water flea, Nile Tilapia and common carp and genotoxicity (Comet assay) were conducted to determine toxicity reduction in leachate along the treatment. Ammonia was found to be the main acute toxic compounds in leachate as determined by LC(50) but the effect of organic substances was also observed. DNA damage in fish exposed to diluted raw leachate (10% of LC(50)) was found to be 8.9-24.3% and it was subsequently decreased along the treatment. Correlation between pollutants and its bio-toxicity was established using multivariable analyses.

  7. Microbial reduction by two chemical-mechanical protocols in primary teeth with pulp necrosis and periradicular lesion - an in vivo study.

    PubMed

    Triches, Thaisa Cezária; de Figueiredo, Luciene Cristina; Feres, Magda; de Freitas, Sérgio Fernando Torres; Zimmermann, Gláucia Santos; Cordeiro, Mabel Mariela Rodríguez

    2014-01-01

    The objective of this study was to determine the efficacy of chemical-mechanical procedures of two endodontic protocols for septic content reduction of root canals from primary teeth with pulp necrosis and periradicular lesion. Twenty-four primary root canals with pulp necrosis and periradicular lesion were divided into two treatment groups (n=12): multiple-visit and single-visit protocols. Samples were collected using sterile paper points before and after endodontic cleaning followed by microbiological identification through checkerboard DNA-DNA hybridization. Statistical analysis was performed using Proportion Test for score=0 comparing the findings before and after treatment for each group (Wilcoxon's test) as well as the differences in scores between protocols (Mann-Whitney's test) (p<0.05). Data were expressed as prevalence (presence or absence) and estimate of the average count (x10(5) cells) of each species. Differences in proportions of score=0 prior to treatment were non-significant (p=0.415), demonstrating equivalence between groups. A significant increase in score=0 was detected after treatment for both groups (p<0.0001). Single-visit protocol achieved a significantly greater reduction in mean scoring following endodontic treatment (p=0.024). Both protocols were capable of significantly reducing septic content in root canals of primary teeth with periradicular lesion. Moreover, single-visit protocol showed greater efficacy in reducing endodontic infection.

  8. Photo and Chemical Reduction of Copper onto Anatase-Type TiO2 Nanoparticles with Enhanced Surface Hydroxyl Groups as Efficient Visible Light Photocatalysts.

    PubMed

    Eskandarloo, Hamed; Badiei, Alireza; Behnajady, Mohammad A; Mohammadi Ziarani, Ghodsi

    2015-01-01

    In this study, the photocatalytic efficiency of anatase-type TiO2 nanoparticles synthesized using the sol-gel low-temperature method, were enhanced by a combined process of copper reduction and surface hydroxyl groups enhancement. UV-light-assisted photo and NaBH4 -assisted chemical reduction methods were used for deposition of copper onto TiO2. The surface hydroxyl groups of TiO2 were enhanced with the assistance of NaOH modification. The prepared catalysts were immobilized on glass plates and used as the fixed-bed systems for the removal of phenazopyridine as a model drug contaminant under visible light irradiation. NaOH-modified Cu/TiO2 nanoparticles demonstrated higher photocatalytic efficiency than that of pure TiO2 due to the extending of the charge carriers lifetime and enhancement of the adsorption capacity of TiO2 toward phenazopyridine. The relationship of structure and performance of prepared nanoparticles has been established by using various techniques, such as XRD, XPS, TEM, EDX, XRF, TGA, DRS and PL. The effects of preparation variables, including copper content, reducing agents rate (NaBH4 concentration and UV light intensity) and NaOH concentration were investigated on the photocatalytic efficiency of NaOH-modified Cu/TiO2 nanoparticles.

  9. Reduction of Surrogates for Escherichia coli O157:H7 and Salmonella during the Production of Nonintact Beef Products by Chemical Antimicrobial Interventions.

    PubMed

    Ulbrich, Carson J; Lucia, Lisa M; Arnold, Ashley N; Taylor, T Matthew; Savell, Jeffrey W; Gehring, Kerri B

    2015-05-01

    The efficacy of chemical antimicrobials for controlling Escherichia coli O157:H7 and Salmonella during production of marinated nonintact beef products was evaluated using nonpathogenic surrogates. Boneless beef strip loins were inoculated with either approximately 5.8 or 1.9 log CFU/cm(2) (high and low inoculation levels, respectively) of nonpathogenic rifampin-resistant E. coli. Inoculated strip loins were chilled at 2°C for 24 h, vacuum packaged, and aged for 7 to 24 days at 2°C. After aging, strip loins received no treatment (control) or one of five antimicrobial spray treatments: 2.5% L-lactic acid (pH 2.6), 5.0% L-lactic acid (pH 2.4), 1,050 ppm of acidified sodium chlorite (pH 2.8), 205 ppm of peroxyacetic acid (pH 5.2), or tap water (pH 8.6). Mean application temperatures were 53, 26, 20, and 18°C for lactic acid, water, peroxyacetic acid, and acidified sodium chlorite treatments, respectively. Treated and control strip loins were vacuum tumbled in a commercial marinade. Samples were collected throughout the experiment to track the effects of antimicrobial treatment and processing on inoculated surrogates. For high-inoculation strip loins, the 5.0% L-lactic acid treatment was most effective for reducing surrogates on meat surfaces before marination, producing a 2.6-log mean reduction. Peroxyacetic acid treatment resulted in the greatest reduction of surface-located surrogate microorganisms in marinated product. Water treatment resulted in greater internalization of surrogate microorganisms compared with the control, as determined by enumeration of surrogates from cored samples. Producers of nonintact beef products should focus on use of validated antimicrobial sprays that maximize microbial reduction and minimize internalization of surface bacteria into the finished product.

  10. Kinetics of the reduction of hematite (Fe{sub 2}O{sub 3}) by methane (CH{sub 4}) during chemical looping combustion: A global mechanism

    SciTech Connect

    Monazam, Esmail R; Breault, Ronald W; Siriwardane, Ranjani; Richards, George; Carpenter, Stephen

    2013-10-01

    Chemical-looping combustion (CLC) has emerged as a promising technology for fossil fuel combustion which produces a sequestration ready concentrated CO{sub 2} stream in power production. A CLC system is composed with two reactors, an air and a fuel reactor. An oxygen carrier such as hematite (94%Fe{sub 2}O{sub 3}) circulates between the reactors, which transfers the oxygen necessary for the fuel combustion from the air to the fuel. An important issue for the CLC process is the selection of metal oxide as oxygen carrier, since it must retain its reactivity through many cycles. The primary objective of this work is to develop a global mechanism with respective kinetics rate parameters such that CFD simulations can be performed for large systems. In this study, thermogravimetric analysis (TGA) of the reduction of hematite (Fe{sub 2}O{sub 3}) in a continuous stream of CH{sub 4} (15, 20, and 35%) was conducted at temperatures ranging from 700 to 825{degrees}C over ten reduction cycles. The mass spectroscopy analysis of product gas indicated the presence of CO{sub 2} and H{sub 2}O at the early stage of reaction and H{sub 2} and CO at the final stage of reactions. A kinetic model based on two parallel reactions, 1) first-order irreversible rate kinetics and 2) Avrami equation describing nucleation and growth processes, was applied to the reduction data. It was found, that the reaction rates for both reactions increase with, both, temperature and the methane concentration in inlet gas.

  11. Reduction of Surrogates for Escherichia coli O157:H7 and Salmonella during the Production of Nonintact Beef Products by Chemical Antimicrobial Interventions.

    PubMed

    Ulbrich, Carson J; Lucia, Lisa M; Arnold, Ashley N; Taylor, T Matthew; Savell, Jeffrey W; Gehring, Kerri B

    2015-05-01

    The efficacy of chemical antimicrobials for controlling Escherichia coli O157:H7 and Salmonella during production of marinated nonintact beef products was evaluated using nonpathogenic surrogates. Boneless beef strip loins were inoculated with either approximately 5.8 or 1.9 log CFU/cm(2) (high and low inoculation levels, respectively) of nonpathogenic rifampin-resistant E. coli. Inoculated strip loins were chilled at 2°C for 24 h, vacuum packaged, and aged for 7 to 24 days at 2°C. After aging, strip loins received no treatment (control) or one of five antimicrobial spray treatments: 2.5% L-lactic acid (pH 2.6), 5.0% L-lactic acid (pH 2.4), 1,050 ppm of acidified sodium chlorite (pH 2.8), 205 ppm of peroxyacetic acid (pH 5.2), or tap water (pH 8.6). Mean application temperatures were 53, 26, 20, and 18°C for lactic acid, water, peroxyacetic acid, and acidified sodium chlorite treatments, respectively. Treated and control strip loins were vacuum tumbled in a commercial marinade. Samples were collected throughout the experiment to track the effects of antimicrobial treatment and processing on inoculated surrogates. For high-inoculation strip loins, the 5.0% L-lactic acid treatment was most effective for reducing surrogates on meat surfaces before marination, producing a 2.6-log mean reduction. Peroxyacetic acid treatment resulted in the greatest reduction of surface-located surrogate microorganisms in marinated product. Water treatment resulted in greater internalization of surrogate microorganisms compared with the control, as determined by enumeration of surrogates from cored samples. Producers of nonintact beef products should focus on use of validated antimicrobial sprays that maximize microbial reduction and minimize internalization of surface bacteria into the finished product. PMID:25951381

  12. Low-temperature selective catalytic reduction of NO with NH3 over nanoflaky MnOx on carbon nanotubes in situ prepared via a chemical bath deposition route

    NASA Astrophysics Data System (ADS)

    Fang, Cheng; Zhang, Dengsong; Cai, Sixiang; Zhang, Lei; Huang, Lei; Li, Hongrui; Maitarad, Phornphimon; Shi, Liyi; Gao, Ruihua; Zhang, Jianping

    2013-09-01

    Nanoflaky MnOx on carbon nanotubes (nf-MnOx@CNTs) was in situ synthesized by a facile chemical bath deposition route for low-temperature selective catalytic reduction (SCR) of NO with NH3. This catalyst was mainly characterized by the techniques of X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), N2 adsorption-desorption analysis, X-ray photoelectron spectroscopy (XPS), H2 temperature-programmed reduction (H2-TPR) and NH3 temperature-programmed desorption (NH3-TPD). The SEM, TEM, XRD results and N2 adsorption-desorption analysis indicated that the CNTs were surrounded by nanoflaky MnOx and the obtained catalyst exhibited a large surface area as well. Compared with the MnOx/CNT and MnOx/TiO2 catalysts prepared by an impregnation method, the nf-MnOx@CNTs presented better NH3-SCR activity at low temperature and a more extensive operating temperature window. The XPS results showed that a higher atomic concentration of Mn4+ and more chemisorbed oxygen species existed on the surface of CNTs for nf-MnOx@CNTs. The H2-TPR and NH3-TPD results demonstrated that the nf-MnOx@CNTs possessed stronger reducing ability, more acid sites and stronger acid strength than the other two catalysts. Based on the above mentioned favourable properties, the nf-MnOx@CNT catalyst has an excellent performance in the low-temperature SCR of NO to N2 with NH3. In addition, the nf-MnOx@CNT catalyst also presented favourable stability and H2O resistance.Nanoflaky MnOx on carbon nanotubes (nf-MnOx@CNTs) was in situ synthesized by a facile chemical bath deposition route for low-temperature selective catalytic reduction (SCR) of NO with NH3. This catalyst was mainly characterized by the techniques of X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), N2 adsorption-desorption analysis, X-ray photoelectron spectroscopy (XPS), H2 temperature-programmed reduction (H2-TPR) and NH3 temperature

  13. Low-temperature selective catalytic reduction of NO with NH₃ over nanoflaky MnOx on carbon nanotubes in situ prepared via a chemical bath deposition route.

    PubMed

    Fang, Cheng; Zhang, Dengsong; Cai, Sixiang; Zhang, Lei; Huang, Lei; Li, Hongrui; Maitarad, Phornphimon; Shi, Liyi; Gao, Ruihua; Zhang, Jianping

    2013-10-01

    Nanoflaky MnO(x) on carbon nanotubes (nf-MnO(x)@CNTs) was in situ synthesized by a facile chemical bath deposition route for low-temperature selective catalytic reduction (SCR) of NO with NH₃. This catalyst was mainly characterized by the techniques of X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), N₂ adsorption-desorption analysis, X-ray photoelectron spectroscopy (XPS), H₂ temperature-programmed reduction (H₂-TPR) and NH₃ temperature-programmed desorption (NH₃-TPD). The SEM, TEM, XRD results and N₂ adsorption-desorption analysis indicated that the CNTs were surrounded by nanoflaky MnO(x) and the obtained catalyst exhibited a large surface area as well. Compared with the MnO(x)/CNT and MnO(x)/TiO₂ catalysts prepared by an impregnation method, the nf-MnO(x)@CNTs presented better NH₃-SCR activity at low temperature and a more extensive operating temperature window. The XPS results showed that a higher atomic concentration of Mn(4+) and more chemisorbed oxygen species existed on the surface of CNTs for nf-MnO(x)@CNTs. The H₂-TPR and NH₃-TPD results demonstrated that the nf-MnO(x)@CNTs possessed stronger reducing ability, more acid sites and stronger acid strength than the other two catalysts. Based on the above mentioned favourable properties, the nf-MnO(x)@CNT catalyst has an excellent performance in the low-temperature SCR of NO to N₂ with NH₃. In addition, the nf-MnO(x)@CNT catalyst also presented favourable stability and H₂O resistance.

  14. Photo-chemical reduction of iodate (IO3-) in sea-water leading to the emission of iodine (I2) in the atmosphere

    NASA Astrophysics Data System (ADS)

    Kumar, R.

    2013-12-01

    Iodine exists in open seawaters mainly in the inorganic forms iodate (IO3-) and iodide (I-). While the concentration of IO3- predominates in deep water, I- concentrations increase toward the surface. The primary precursor for iodine oxide particle (IOP) formation in the coastal marine boundary layer (MBL) is iodine (I2) originating from exposed macroalgae. In contrast, recent field measurements of IO above the open ocean suggest that biogenic organic-iodine emissions cannot account for the observed levels. Thus, the alternative mechanisms include the reduction of IO3- to I- in seawater which in turn is converted to, and emitted as I2 to the atmosphere which may contribute to observed levels of I2 in the MBL. In this study a series of laboratory investigations of the photo-chemical reduction of iodate (IO3-) to both aqueous iodide (I-) and a bound, soluble iodinated organic form have been conducted to investigate three potentially important processes likely to participate in the recycling of I2 from seawater in the presence of sunlight: (i) the role of dissolved organic materials (i.e. humic acid), (ii) the effect of salinity (Cl- concentration) and (iii) deposition and uptake of O3. The experiments involved the initial photolysis of IO3- solutions with either humic acid or Cl- added. The formation of I- in solution (due to IO3- reduction) was detected using time-resolved UV-Vis spectroscopy. Oxidation of iodide ions to I2 formation in the solutions and release to the gas-phase was confirmed indirectly by the detection of iodine oxide particles (IOPs) generated by the photo-oxidation of the gas-phase I2 released from solution using a coupled differential mobility analyser (DMA) and Faraday cup electrometer (FCE) system. The results indicate a constant fraction of ~ 20% of reduced iodate is in the form free iodide (I-) and by difference, ~ 80% of reduced iodate is most likely in an iodinated humic acid. Iodine (I2) is emitted by the uptake of ozone on iodide (I

  15. Sodium Borohydride Reduction of Aqueous Silver-Iron-Nickel Solutions: a Chemical Route to Synthesis of Low Thermal Expansion-High Conductivity Ag-Invar Alloys

    NASA Astrophysics Data System (ADS)

    Sterling, E. A.; Stolk, J.; Hafford, L.; Gross, M.

    2009-07-01

    Thermal management is a critical concern in the design and performance of electronics systems. If heat extraction and thermal expansion are not properly addressed, the thermal mismatch among dissimilar materials may give rise to high thermal stresses or interfacial shear strains, and ultimately to premature system failure. In this article, we present a chemical synthesis process that yields Ag-Invar (64Fe-36Ni) alloys with a range of attractive properties for thermal management applications. Sodium borohydride reduction of an aqueous Ag-Fe-Ni metal salt solution produces nanocrystalline powders, and conventional powder processing converts this powder to fine-grained alloys. The samples are characterized by X-ray diffraction (XRD), scanning electron microscopy, thermomechanical analysis, and electrical conductivity measurements; thermal conductivity is estimated using the Wiedemann-Franz law. Sintering of Ag-Fe-Ni powders leads to the formation of two-phase silver-Invar alloys with low coefficients of thermal expansion (CTEs) and relatively high electrical conductivities. A sample of 50Ag-50Invar exhibits a CTE of 8.76 μm/(m· °C) and an estimated thermal conductivity of 236 W/(m·K). The Ag-Invar alloys offer thermodynamic stability and tailorable properties, and they may help address the need for improved packaging materials.

  16. Chemical speciation of PM emissions from heavy-duty diesel vehicles equipped with diesel particulate filter (DPF) and selective catalytic reduction (SCR) retrofits

    NASA Astrophysics Data System (ADS)

    Biswas, Subhasis; Verma, Vishal; Schauer, James J.; Sioutas, Constantinos

    Four heavy-duty diesel vehicles (HDDVs) in six retrofitted configurations (CRT ®, V-SCRT ®, Z-SCRT ®, Horizon, DPX and CCRT ®) and a baseline vehicle operating without after--treatment were tested under cruise (50 mph), transient UDDS and idle driving modes. As a continuation of the work by Biswas et al. [Biswas, S., Hu, S., Verma, V., Herner, J., Robertson, W.J., Ayala, A., Sioutas, C., 2008. Physical properties of particulate matter (PM) from late model heavy-duty diesel vehicles operating with advanced emission control technologies. Atmospheric Environment 42, 5622-5634.] on particle physical parameters, this paper focuses on PM chemical characteristics (Total carbon [TC], Elemental carbon [EC], Organic Carbon [OC], ions and water-soluble organic carbon [WSOC]) for cruise and UDDS cycles only. Size-resolved PM collected by MOUDI-Nano-MOUDI was analyzed for TC, EC and OC and ions (such as sulfate, nitrate, ammonium, potassium, sodium and phosphate), while Teflon coated glass fiber filters from a high volume sampler were extracted to determine WSOC. The introduction of retrofits reduced PM mass emissions over 90% in cruise and 95% in UDDS. Similarly, significant reductions in the emission of major chemical constituents (TC, OC and EC) were achieved. Sulfate dominated PM composition in vehicle configurations (V-SCRT ®-UDDS, Z-SCRT ®-Cruise, CRT ® and DPX) with considerable nucleation mode and TC was predominant for configurations with less (Z-SCRT ®-UDDS) or insignificant (CCRT ®, Horizon) nucleation. The transient operation increases EC emissions, consistent with its higher accumulation PM mode content. In general, solubility of organic carbon is higher (average ˜5 times) for retrofitted vehicles than the baseline vehicle. The retrofitted vehicles with catalyzed filters (DPX, CCRT ®) had decreased OC solubility (WSOC/OC: 8-25%) unlike those with uncatalyzed filters (SCRT ®s, Horizon; WSOC/OC ˜ 60-100%). Ammonium was present predominantly in the

  17. Use of HPLC/UPLC-spectrophotometry for detection of formazan in in vitro Reconstructed human Tissue (RhT)-based test methods employing the MTT-reduction assay to expand their applicability to strongly coloured test chemicals.

    PubMed

    Alépée, N; Barroso, J; De Smedt, A; De Wever, B; Hibatallah, J; Klaric, M; Mewes, K R; Millet, M; Pfannenbecker, U; Tailhardat, M; Templier, M; McNamee, P

    2015-06-01

    A number of in vitro test methods using Reconstructed human Tissues (RhT) are regulatory accepted for evaluation of skin corrosion/irritation. In such methods, test chemical corrosion/irritation potential is determined by measuring tissue viability using the photometric MTT-reduction assay. A known limitation of this assay is possible interference of strongly coloured test chemicals with measurement of formazan by absorbance (OD). To address this, Cosmetics Europe evaluated use of HPLC/UPLC-spectrophotometry as an alternative formazan measurement system. Using the approach recommended by the FDA guidance for validation of bio-analytical methods, three independent laboratories established and qualified their HPLC/UPLC-spectrophotometry systems to reproducibly measure formazan from tissue extracts. Up to 26 chemicals were then tested in RhT test systems for eye/skin irritation and skin corrosion. Results support that: (1) HPLC/UPLC-spectrophotometry formazan measurement is highly reproducible; (2) formazan measurement by HPLC/UPLC-spectrophotometry and OD gave almost identical tissue viabilities for test chemicals not exhibiting colour interference nor direct MTT reduction; (3) independent of the test system used, HPLC/UPLC-spectrophotometry can measure formazan for strongly coloured test chemicals when this is not possible by absorbance only. It is therefore recommended that HPLC/UPLC-spectrophotometry to measure formazan be included in the procedures of in vitro RhT-based test methods, irrespective of the test system used and the toxicity endpoint evaluated to extend the applicability of these test methods to strongly coloured chemicals.

  18. IN SITU CHEMICAL REDUCTION OF CR(VI) IN GROUNDWATER USING A COMBINATION OF FERROUS SULFATE AND SODIUM DITHIONITE: A FIELD INVESTIGATION

    EPA Science Inventory

    A field pilot test was conducted to evaluate the effectiveness of a FeSO4 + Na2S2O4 reductant solution blend for in situ saturated zone treatment of dissolved-phase Cr(VI) at the former Macalloy Corporation site in Charleston, SC. The reductant blend was injected into the path o...

  19. Impact of reaction parameters on the chemical profile of 3,4-methylenedioxymethamphetamine synthesized via reductive amination: target analysis based on GC-qMS compared to non-targeted analysis based on GC×GC-TOF-MS.

    PubMed

    Schäffer, M; Dieckmann, S; Pütz, M; Kohles, T; Pyell, U; Zimmermann, R

    2013-12-10

    The most common clandestine manufacturing procedure for the ecstasy derivative 3,4-methylenedioxymethamphetamine (MDMA), is the reductive amination of piperonylmethylketone (PMK) via platinum(IV) oxide/hydrogen. Deviations of the reaction conditions during the synthesis may result in different chemical profiles of the products. The chemical analysis of these profiles is an important objective for forensic drug intelligence. In this work we studied the impact of a systematic variation of the hydrogenation time, the reaction temperature and the precursor batch on the resulting organic chemical profiles of the MDMA bases and MDMA hydrochlorides. Target analysis was based on a gas chromatography mass spectrometry (GC-MS) method which was harmonized during the European project CHAMP.(2) In addition, samples were analyzed by comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC×GC-TOFMS) and subjected to non-targeted data analysis for a comprehensive analysis of the complete profiles. The reaction temperature, followed by the used precursor batch, revealed the highest impact on the chemical profile. The effect on individual impurity compounds is discussed in detail. With respect to the interpretation of the data, the profiles were compared to the profiles of MDMA samples obtained by reductive amination using sodium borohydride ("cold method") and aluminium/mercury amalgam as alternative reducing agents. Non-targeted analysis revealed that the discrimination according to the synthetic route and the batch of precursor used for the synthesis strongly depends on the selected target compounds.

  20. Use of HPLC/UPLC-spectrophotometry for detection of formazan in in vitro Reconstructed human Tissue (RhT)-based test methods employing the MTT-reduction assay to expand their applicability to strongly coloured test chemicals.

    PubMed

    Alépée, N; Barroso, J; De Smedt, A; De Wever, B; Hibatallah, J; Klaric, M; Mewes, K R; Millet, M; Pfannenbecker, U; Tailhardat, M; Templier, M; McNamee, P

    2015-06-01

    A number of in vitro test methods using Reconstructed human Tissues (RhT) are regulatory accepted for evaluation of skin corrosion/irritation. In such methods, test chemical corrosion/irritation potential is determined by measuring tissue viability using the photometric MTT-reduction assay. A known limitation of this assay is possible interference of strongly coloured test chemicals with measurement of formazan by absorbance (OD). To address this, Cosmetics Europe evaluated use of HPLC/UPLC-spectrophotometry as an alternative formazan measurement system. Using the approach recommended by the FDA guidance for validation of bio-analytical methods, three independent laboratories established and qualified their HPLC/UPLC-spectrophotometry systems to reproducibly measure formazan from tissue extracts. Up to 26 chemicals were then tested in RhT test systems for eye/skin irritation and skin corrosion. Results support that: (1) HPLC/UPLC-spectrophotometry formazan measurement is highly reproducible; (2) formazan measurement by HPLC/UPLC-spectrophotometry and OD gave almost identical tissue viabilities for test chemicals not exhibiting colour interference nor direct MTT reduction; (3) independent of the test system used, HPLC/UPLC-spectrophotometry can measure formazan for strongly coloured test chemicals when this is not possible by absorbance only. It is therefore recommended that HPLC/UPLC-spectrophotometry to measure formazan be included in the procedures of in vitro RhT-based test methods, irrespective of the test system used and the toxicity endpoint evaluated to extend the applicability of these test methods to strongly coloured chemicals. PMID:25701760

  1. N2O production in the Fe(II)(EDTA)-NO reduction process: the effects of carbon source and pH.

    PubMed

    Chen, Jun; Wang, Lei; Zheng, Ji; Chen, Jianmeng

    2015-07-01

    Chemical absorption-biological reduction (BioDeNOx), which uses Fe(II)(EDTA) as a complexing agent for promoting the mass transfer efficiency of NO from gas to water, is a promising technology for removing nitric oxide (NO) from flue gases. The carbon source and pH are important parameters for Fe(II)(EDTA)-NO (the production of absorption) reduction and N2O emissions from BioDeNOx systems. Batch tests were performed to evaluate the effects of four different carbon sources (i.e., methanol, ethanol, sodium acetate, and glucose) on Fe(II)(EDTA)-NO reduction and N2O emissions at an initial pH of 7.2 ± 0.2. The removal efficiency of Fe(II)(EDTA)-NO was 93.9%, with a theoretical rate of 0.77 mmol L(-1) h(-1) after 24 h of operation. The highest N2O production was 0.025 mmol L(-1) after 3 h when glucose was used as the carbon source. The capacities of the carbon sources to enhance the activity of the Fe(II)(EDTA)-NO reductase enzyme decreased in the following order based on the C/N ratio: glucose > ethanol > sodium acetate > methanol. Over the investigated pH range of 5.5-8.5, the Fe(II)(EDTA)-NO removal efficiency was highest at a pH of 7.5, with a theoretical rate of 0.88 mmol L(-1) h(-1). However, the N2O production was lowest at a pH of 8.5. The primary effect of pH on denitrification resulted from the inhibition of nosZ in acidic conditions.

  2. Screening of the chemical reactivity of three different graphite sources using the formation of reductively alkylated graphene as a model reaction.

    PubMed

    Knirsch, Kathrin C; Englert, Jan M; Dotzer, Christoph; Hauke, Frank; Hirsch, Andreas

    2013-11-28

    Reductive alkylation of three graphite starting materials G(flake), G(powder), and G(spherical) reveals pronounced differences in the obtained covalently functionalized graphene with respect to the degree of functionalization, exfoliation efficiency and product homogeneity, as demonstrated by statistical Raman microscopy (SRM), TGA/MS, IR-spectroscopy and solubility behavior.

  3. A COMPARATIVE RISK REDUCTION ANALYSIS OF THE OFFICE OF SOLID WASTE'S WASTE MINIMIZATION PRIORITY CHEMICALS INITIATIVE USING THE 3MRA MULTIMEDIA MODELING SYSTEM

    EPA Science Inventory

    A study was initiated by the EPA/ORD National Exposure Research Lab (NERL) in FY05 to quantify risk reduction resulting from this national EPA initiative to reduce WMPC disposal. Using the 3MRA modeling system, which was recommended for use by the EPA Science Advisory Board for ...

  4. Effect of natural Bayah zeolite particle size reduction to physico-chemical properties and absortion against potassium permanganate (KMnO4)

    NASA Astrophysics Data System (ADS)

    Widayanti, Siti Mariana; Syamsu, Khaswar; Warsiki, Endang; Yuliani, Sri

    2016-02-01

    Recently, researches on nanotechnology have been developed very rapid, as well as the utilization of nano-zeolites. Nano-sized material has several advantages which are expanding absorptive surfaces so it will enhance the material absorption and shorten the absorption time. Zeolite as a KMnO4 binder, has been widely recognized for its ability to extend the shelf life of vegetables and fruits. This study was conducted to determine zeolites physico-chemical characters from different particle size and the effect on KMnO4 absorption. Potassium permanganate (KMnO4) is a strong oxidizer for reducing the quantity of ethylene in storage process of fresh horticultural products. The treatment consisted of (1) different length of milling time (10, 20, 30, 40, and 60 minutes) and (2) the duration of chemical activation with 1 N KOH solution. Physical and chemical characters of zeolite were analyzed using BET, PSA, XRD and SEM. The research design was randomized design. The result implied that milling time was significantly affecting the zeolite particle size, material surface area, and the size of pore diameter and volume. Milling treatment for 40 minutes produced higher zeolite surface area and pore volume than other treatments. While the duration of chemical activation using 1 N KOH solution gives different effect on zeolite absorption to KMnO4 solution. Milling time for 60 minutes and activated for 48 hours has higher initial adsorption than other treatments.

  5. Studies of chemical reduction of Fe(III)*EDTA in an SO{sub 2}/NO{sub x} aqueous scrubber system

    SciTech Connect

    Li, W.; Keener, T.C.; Mendelsohn, M.; Harkness, J.B.L.; Livengood, C.D.

    1996-03-01

    Ferrous*EDTA has been found to be an effective scrubbing agent for nitric oxide gas. A major process problem is oxidation of the iron to the ferric species, leading to a significant decrease in NO{sub x}-removal capability. Argonne National Laboratory discovered a class of organic compounds that, when used with ferrous*EDTA in a sodium carbonate chemistry, could maintain high levels of NO{sub x} removal. However, those antioxidant/reducing agents (A/R) are not effective in a lime-based chemistry. In recent reports, it has been found that ascorbic acid and related compounds are capable of maintaining stable NO{sub x} removals of about 50% (compared with about 15% without the agent) in a lime-based FGD chemistry with Fe(II)*EDTA. It is believed that the improved performance of Fe(II)*EDTA is due to the catalytic action of ascorbate in the Fe(III)*EDTA reduction system, where Fe(III)*EDTA is reduced by ascorbate and oxidized ascorbate is then reduced back to the ascorbate by sulfite/bisulfite anions, which come from the dissolution of SO{sub 2} in the flue gas. In the present work, the kinetics of the reduction of ferric chelate by ascorbate and reduction of oxidized ascorbate by sulfite/bisulfite anions at a typical flue-gas scrubber-system operating temperature ({approximately}55 C) have been determined.

  6. Reductive activation in periplasmic nitrate reductase involves chemical modifications of the Mo-cofactor beyond the first coordination sphere of the metal ion.

    PubMed

    Jacques, Julien G J; Fourmond, Vincent; Arnoux, Pascal; Sabaty, Monique; Etienne, Emilien; Grosse, Sandrine; Biaso, Frédéric; Bertrand, Patrick; Pignol, David; Léger, Christophe; Guigliarelli, Bruno; Burlat, Bénédicte

    2014-02-01

    In Rhodobacter sphaeroides periplasmic nitrate reductase NapAB, the major Mo(V) form (the "high g" species) in air-purified samples is inactive and requires reduction to irreversibly convert into a catalytically competent form (Fourmond et al., J. Phys. Chem., 2008). In the present work, we study the kinetics of the activation process by combining EPR spectroscopy and direct electrochemistry. Upon reduction, the Mo (V) "high g" resting EPR signal slowly decays while the other redox centers of the protein are rapidly reduced, which we interpret as a slow and gated (or coupled) intramolecular electron transfer between the [4Fe-4S] center and the Mo cofactor in the inactive enzyme. Besides, we detect spin-spin interactions between the Mo(V) ion and the [4Fe-4S](1+) cluster which are modified upon activation of the enzyme, while the EPR signatures associated to the Mo cofactor remain almost unchanged. This shows that the activation process, which modifies the exchange coupling pathway between the Mo and the [4Fe-4S](1+) centers, occurs further away than in the first coordination sphere of the Mo ion. Relying on structural data and studies on Mo-pyranopterin and models, we propose a molecular mechanism of activation which involves the pyranopterin moiety of the molybdenum cofactor that is proximal to the [4Fe-4S] cluster. The mechanism implies both the cyclization of the pyran ring and the reduction of the oxidized pterin to give the competent tricyclic tetrahydropyranopterin form.

  7. Chemical Reduction of Nd 1.85 Ce 0.15 CuO 4− δ Powders in Supercritical Sodium Ammonia Solutions

    DOE PAGES

    Dias, Yasmin; Wang, Hui; Zhou, Haiqing; Lin, Feng; Lan, Yucheng

    2015-01-01

    Nd 1.85 Ce 0.15 CuO 4− δ powders are chemically reduced in supercritical sodium ammonia solutions from room temperature to 350°C. The crystallographic structure of the reduced powders is investigated from Rietveld refinement of X-ray powder diffraction. The atomic positions are maintained constant within experimental errors while temperature factors of all atoms increase significantly after the chemical treatments, especially of Nd/Ce atoms. The ammonothermally reduced Nd 1.85 Ce 0.15 CuO 4− δ powders show diamagnetic below 24 K which is contributed to the lower oxygen content and higher temperature factors of atoms in the treated compound.more » The ammonothermal method paves a new way to reduce oxides in supercritical solutions near room temperature.« less

  8. Evolution of the Structure and Chemical State of Pd Nanoparticles During the in Situ Catalytic Reduction of NO with H2

    SciTech Connect

    K Paredis; L Ono; F Behafarid; Z Zhang; J Yang; A Frenkel; B Roldan Cuenya

    2011-12-31

    An in-depth understanding of the fundamental structure of catalysts during operation is indispensable for tailoring future efficient and selective catalysts. We report the evolution of the structure and oxidation state of ZrO{sub 2}-supported Pd nanocatalysts (5 nm) during the in situ reduction of NO with H{sub 2} using X-ray absorption fine-structure spectroscopy and X-ray photoelectron spectroscopy. Prior to the onset of the reaction ({le}120 C), a NO-induced redispersion of our initial metallic Pd nanoparticles over the ZrO{sub 2} support was observed, and Pd{sup {delta}+} species were detected. This process parallels the high production of N{sub 2}O observed at the onset of the reaction (>120 C), while at higher temperatures ({ge}150 C) the selectivity shifts mainly toward N{sub 2} ({approx}80%). Concomitant with the onset of N{sub 2} production, the Pd atoms aggregate again into large (6.5 nm) metallic Pd nanoparticles, which were found to constitute the active phase for the H{sub 2}-reduction of NO. Throughout the entire reaction cycle, the formation and stabilization of PdO{sub x} was not detected. Our results highlight the importance of in situ reactivity studies to unravel the microscopic processes governing catalytic reactivity.

  9. Hydrogen production from the steam-iron process with direct reduction of iron oxide by chemical looping combustion of coal char

    SciTech Connect

    Jing-biao Yang; Ning-sheng Cai; Zhen-shan Li

    2008-07-15

    Experimental results performed with a fluidized-bed reactor supported the feasibility of the three processes including direct reduction of iron oxide by char, H{sub 2} production by the steam-iron process, and the oxidation of Fe{sub 3}O{sub 4} resulting from the steam-iron process to the original Fe{sub 2}O{sub 3} by air. Chars resulting from a Chinese lignite loaded with K{sub 2}CO{sub 3} were used successfully as a reducing material, leading to the reduction of Fe{sub 2}O{sub 3} to FeO and Fe for the steam-iron process, which was confirmed by both the off-gases concentrations and X-ray diffractometer analysis. The reduction of Fe{sub 2}O{sub 3} by K-10-char at 1073 K is desirable from the perspective of the carbon conversion rate and high concentration of CO{sub 2}. The carbon in char was completely converted to CO{sub 2} when the mass ratio of Fe{sub 2}O{sub 3}/K-10-char was increased to 10/0.3. The oxidation rate of K-10-char by Fe{sub 2}O{sub 3} without a gasifying agent was comparable to the K-10-char steam gasification rate. The fractions of FeO and Fe in the reduced residue were 43 and 57%, respectively, in the case of 3 g of Fe{sub 2}O{sub 3} and 0.5 g of K-10-char, which was verified by the total H{sub 2} yield equaling 1000 mL/g K-10-char from the steam-iron process. The time that it took to achieve complete oxidation of Fe{sub 3}O{sub 4} to Fe{sub 2}O{sub 3} by air with an 8.7% O{sub 2} concentration at 1073 K was about 15 min. 53 refs., 19 figs., 5 tabs.

  10. Development and Application of Computational/In Vitro Toxicological Methods for Chemical Hazard Risk Reduction of New Materials for Advanced Weapon Systems

    NASA Technical Reports Server (NTRS)

    Frazier, John M.; Mattie, D. R.; Hussain, Saber; Pachter, Ruth; Boatz, Jerry; Hawkins, T. W.

    2000-01-01

    The development of quantitative structure-activity relationship (QSAR) is essential for reducing the chemical hazards of new weapon systems. The current collaboration between HEST (toxicology research and testing), MLPJ (computational chemistry) and PRS (computational chemistry, new propellant synthesis) is focusing R&D efforts on basic research goals that will rapidly transition to useful products for propellant development. Computational methods are being investigated that will assist in forecasting cellular toxicological end-points. Models developed from these chemical structure-toxicity relationships are useful for the prediction of the toxicological endpoints of new related compounds. Research is focusing on the evaluation tools to be used for the discovery of such relationships and the development of models of the mechanisms of action. Combinations of computational chemistry techniques, in vitro toxicity methods, and statistical correlations, will be employed to develop and explore potential predictive relationships; results for series of molecular systems that demonstrate the viability of this approach are reported. A number of hydrazine salts have been synthesized for evaluation. Computational chemistry methods are being used to elucidate the mechanism of action of these salts. Toxicity endpoints such as viability (LDH) and changes in enzyme activity (glutahoione peroxidase and catalase) are being experimentally measured as indicators of cellular damage. Extrapolation from computational/in vitro studies to human toxicity, is the ultimate goal. The product of this program will be a predictive tool to assist in the development of new, less toxic propellants.

  11. Termination of light-water reactor core-melt accidents with a chemical core catcher: the core-melt source reduction system (COMSORS)

    SciTech Connect

    Forsberg, C.W.; Parker, G.W.; Rudolph, J.C.; Osborne-Lee, I.W.; Kenton, M.A.

    1996-09-01

    The Core-Melt Source Reduction System (COMSORS) is a new approach to terminate light-water reactor core melt accidents and ensure containment integrity. A special dissolution glass is placed under the reactor vessel. If core debris is released onto the glass, the glass melts and the debris dissolves into the molten glass, thus creating a homogeneous molten glass. The molten glass, with dissolved core debris, spreads into a wide pool, distributing the heat for removal by radiation to the reactor cavity above or by transfer to water on top of the molten glass. Expected equilibrium glass temperatures are approximately 600 degrees C. The creation of a low-temperature, homogeneous molten glass with known geometry permits cooling of the glass without threatening containment integrity. This report describes the technology, initial experiments to measure key glass properties, and modeling of COMSORS operations.

  12. Direct determination of arsenic in soil samples by fast pyrolysis-chemical vapor generation using sodium formate as a reductant followed by nondispersive atomic fluorescence spectrometry

    NASA Astrophysics Data System (ADS)

    Duan, Xuchuan; Zhang, Jingya; Bu, Fanlong

    2015-09-01

    This new study shows for the first time that sodium formate can react with trace arsenic to form volatile species via fast pyrolysis - chemical vapor generation. We found that the presence of thiourea greatly enhanced the generation efficiency and eliminated the interference of copper. We studied the reaction temperature, the volume of sodium formate, the reaction acidity, and the carried argon rate using nondispersive atomic fluorescence spectrometry. Under optimal conditions of T = 500 °C, the volumes of 30% sodium formate and 10% thiourea were 0.2 ml and 0.05 ml, respectively. The carrier argon rate was 300 ml min- 1 and the detection limit and precision of arsenic were 0.39 ng and 3.25%, respectively. The amount of arsenic in soil can be directly determined by adding trace amount of hydrochloric acid as a decomposition reagent without any sample pretreatment. The method was successfully applied to determine trace amount of arsenic in two soil-certified reference materials (GBW07453 and GBW07450), and the results were found to be in agreement with certified reference values.

  13. Chemical Domino Demonstration

    NASA Astrophysics Data System (ADS)

    Alexander, M. Dale

    1998-04-01

    The Chemical Domino Demonstration is both educational and entertaining. It provides an excellent means for a review of chemical concepts at the conclusion of a general chemistry course. This demonstration consists of a number of different chemical reactions occurring in sequence in a Rube Goldberg-type apparatus. These reactions include the reduction of water by an active metal, the oxidation of a moderately active metal by an acid, reduction of metallic ions by a metal of greater activity, acid-base neutralization reactions in solution monitored with indicators, a gas-phase acid-base neutralization reaction, decomposition of a compound, precipitation of an insoluble salt, substitution reactions of coordination complexes, and pyrotechnic oxidation-reduction reactions including a hypergolic oxidation-reduction reaction, an intramolecular oxidation-reduction reaction, and the combustion of a flammable gas.

  14. Oxidation, Reduction, and Deoxygenation

    NASA Astrophysics Data System (ADS)

    Madsen, Robert

    In this chapter, methods for oxidation, reduction, and deoxygenation of carbohydrates are presented. In most cases, the reactions have been used on aldoses and their derivatives including glycosides, uronic acids, glycals, and other unsaturated monosaccharides. A number of reactions have also been applied to aldonolactones. The methods include both chemical and enzymatic procedures and some of these can be applied for regioselective transformation of unprotected or partially protected carbohydrates.

  15. Industrial Waste Reduction Program

    SciTech Connect

    Not Available

    1991-10-24

    US industry generates over 12 billion tons of wastes each year. These wastes consist of undesirable by-products of industrial production that are discarded into our environment. Energy is an integral part of these wastes; it is found in the embodied energy of industrial feedstocks not optimally used, in the energy content of the wastes themselves, and in the energy needed to transport, treat, and dispose of wastes. Estimates of the potential energy savings from reducing industrial wastes range from three to four quadrillion Btu per year -- enough to meet the annual energy needs of 30 million American homes. This document presents a plan for the Industrial Waste Reduction Program, which has been designed to help achieve national goals for energy efficiency and waste minimization. The objective of the program is to improve the energy efficiency of industrial processes through cost-effective waste reduction. The initial program focus is on waste reduction opportunities in the production and use of chemicals, due to the significant amount of energy used in these activities and the large amounts of hazardous and toxic wastes they generate. The chemical industry will be the initial subject of a series of waste reduction opportunity assessments conducted as part of the program. Assessments of other industries and waste problems will follow.

  16. Examination of surface phenomena of V₂O₅ loaded on new nanostructured TiO₂ prepared by chemical vapor condensation for enhanced NH₃-based selective catalytic reduction (SCR) at low temperatures.

    PubMed

    Cha, Woojoon; Yun, Seong-Taek; Jurng, Jongsoo

    2014-09-01

    In this article, we describe the investigation and surface characterization of a chemical vapor condensation (CVC)-TiO2 support material used in a V2O5/TiO2 catalyst for enhanced selective catalytic reduction (SCR) activity and confirm the mechanism of surface reactions. On the basis of previous studies and comparison with a commercial TiO2 catalyst, we examine four fundamental questions: first, the reason for increased surface V(4+) ion concentrations; second, the origin of the increase in surface acid sites; third, a basis for synergistic influences on improvements in SCR activity; and fourth, a reason for improved catalytic activity at low reaction temperatures. In this study, we have cited the result of SCR with NH3 activity for removing NOx and analyzed data using the reported result and data from previous studies on V2O5/CVC-TiO2 for the SCR catalyst. In order to determine the properties of suitable CVC-TiO2 surfaces for efficient SCR catalysis at low temperatures, CVC-TiO2 specimens were prepared and characterized using techniques such as XRD, BET, HR-TEM, XPS, FT-IR, NH3-TPD, photoluminescence (PL) spectroscopy, H2-TPR, and cyclic voltammetry. The results obtained for the CVC-TiO2 materials were also compared with those of commercial TiO2. PMID:25045767

  17. Examination of surface phenomena of V₂O₅ loaded on new nanostructured TiO₂ prepared by chemical vapor condensation for enhanced NH₃-based selective catalytic reduction (SCR) at low temperatures.

    PubMed

    Cha, Woojoon; Yun, Seong-Taek; Jurng, Jongsoo

    2014-09-01

    In this article, we describe the investigation and surface characterization of a chemical vapor condensation (CVC)-TiO2 support material used in a V2O5/TiO2 catalyst for enhanced selective catalytic reduction (SCR) activity and confirm the mechanism of surface reactions. On the basis of previous studies and comparison with a commercial TiO2 catalyst, we examine four fundamental questions: first, the reason for increased surface V(4+) ion concentrations; second, the origin of the increase in surface acid sites; third, a basis for synergistic influences on improvements in SCR activity; and fourth, a reason for improved catalytic activity at low reaction temperatures. In this study, we have cited the result of SCR with NH3 activity for removing NOx and analyzed data using the reported result and data from previous studies on V2O5/CVC-TiO2 for the SCR catalyst. In order to determine the properties of suitable CVC-TiO2 surfaces for efficient SCR catalysis at low temperatures, CVC-TiO2 specimens were prepared and characterized using techniques such as XRD, BET, HR-TEM, XPS, FT-IR, NH3-TPD, photoluminescence (PL) spectroscopy, H2-TPR, and cyclic voltammetry. The results obtained for the CVC-TiO2 materials were also compared with those of commercial TiO2.

  18. Waste Reduction.

    ERIC Educational Resources Information Center

    Bray, Marilyn; And Others

    1996-01-01

    Presents activities that focus on waste reduction in the school and community. The ideas are divided into grade level categories. Sample activities include Techno-Trash, where children use tools to take apart broken appliances or car parts, then reassemble them or build new creations. Activities are suggested for areas including language arts and…

  19. Nitrate reduction

    DOEpatents

    Dziewinski, Jacek J.; Marczak, Stanislaw

    2000-01-01

    Nitrates are reduced to nitrogen gas by contacting the nitrates with a metal to reduce the nitrates to nitrites which are then contacted with an amide to produce nitrogen and carbon dioxide or acid anions which can be released to the atmosphere. Minor amounts of metal catalysts can be useful in the reduction of the nitrates to nitrites. Metal salts which are formed can be treated electrochemically to recover the metals.

  20. Selective reduction.

    PubMed

    Evans, Mark I; Krivchenia, Eric L; Gelber, Shari E; Wapner, Ronald J

    2003-03-01

    Multifetal pregnancy reduction continues to be controversial. Attitudes about MFPR have not, in our experience, followed a simple "pro-choice/pro-life" dichotomy. As far back as the mid to late 1980s, opinions about the subject were varied. Even then, when much less was known about the subject, opinions did not always parallel the usual pro-choice/theological boundaries. We believe that the real debate over the next 5 to 10 years will not be whether or not MFPR should be performed with triplets or more. The fact is that MFPR does improve those outcomes. A serious debate will emerge over whether or not it is appropriate to offer MFPR routinely for twins, even natural ones, for whom the outcome is commonly considered "good enough." Our data suggest that reduction of twins to a singleton improves the outcome of the remaining fetus. No consensus on appropriateness of routine 2-1 reductions is ever likely to emerge. The ethical issues surrounding MFPR will always be controversial. Over the years, much has been written on the subject. Opinions will always vary from outraged condemnation to complete acceptance. No short paragraph could do justice to the subject other than to state that most proponents do not believe this is a frivolous procedure but do believe in the principle of proportionality ie, therapy to achieve the most good for the least harm). Over the past 15 years, MFPR has become a well-established and integral part of infertility therapy and attempts to deal with the sequelae of aggressive infertility management. In the mid 1980s, the risks and benefits of the procedure could only be guessed. We now have clear and precise data on the risks and benefits of the procedure and an understanding that the risks increase substantially with the starting and finishing number of fetuses in multifetal pregnancies. The collaborative loss rate numbers (ie, 4.5% for triplets, 8% for quadruplets. 11% for quintuplets, and 15% for sextuplets or more) seem reasonable to present

  1. Modern Chemical Technology, Volume 5.

    ERIC Educational Resources Information Center

    Pecsok, Robert L., Ed.; Chapman, Kenneth, Ed.

    This volume contains chapters 26-31 for the American Chemical Society (ACS) "Modern Chemical Technology" (ChemTeC) instructional material intended to prepare chemical technologists. Chapter 26 reviews oxidation and reduction, including applications in titrations with potassium permanganate and iodometry. Coordination compounds are described in the…

  2. Chemical exchange program analysis.

    SciTech Connect

    Waffelaert, Pascale

    2007-09-01

    unneeded chemicals and the amount spent on new purchases, but will also avoid disposal costs. If SNL/NM were to realize a 5 percent reduction in chemical inventory and a 10 percent reduction in disposal of unused chemicals the total savings would be $189, 200 per year.

  3. The Industrial Reduction of Aromatic Nitro Compounds.

    ERIC Educational Resources Information Center

    Gilbert, G.

    1980-01-01

    Describes methods for enriching an A-level chemistry course with a series of chemical company visits. The rationale is discussed for an emphasis of the visits on the industrial reduction of aromatic nitro compounds. (CS)

  4. Some Early Usages of Chemical Terms

    ERIC Educational Resources Information Center

    Oldroyd, D. R.

    1973-01-01

    Discusses the origins of such chemical terms as substance, element, analysis, synthesis, compounds, mixture, organic,'' affinity, oxidation, reduction, acid, base, and salt for the purpose of providing a background to facilitate student's understanding of chemical terminology. (CC)

  5. REPEATED REDUCTIVE AND OXIDATIVE TREATMENTS ON GRANULAR ACTIVATED CARBON

    EPA Science Inventory

    Fenton oxidation and Fenton oxidation preceded by reduction solutions were applied to granular activated carbon (GAC) to chemically regenerate the adsorbent. No adsorbate was present on the GAC so physicochemical effects from chemically aggressive regeneration of the carbon coul...

  6. Sterol synthesis. A novel reductive rearrangement of an alpha,beta-unsaturated steroidal epoxide; a new chemical synthesis of 5alpha-cholest-8(14)-en-3beta, 15alpha-diol.

    PubMed

    Parish, E J; Schroepfer, G J

    1977-04-01

    Reduction of 3beta-benzoyloxy-14alpha,15alpha-epoxy-5alpha-cholest-7-ene with either lithium triethylboro-hydride or lithium aluminum hydride (4 molar excess) gave 5-alpha-cholest-8(14)-en-3beta,15alpha-diol in high yield. Reduction of the epoxy ester with lithium triethylborodeuteride or lithium aluminum deuteride (4 molar excess) gave [7alpha-2-H]-5alpha-cholest-8(14)-en-3beta,15alpha-diol. Reduction of 2beta-benzoyloxy-14alpha,15alpha-epoxy-5alpha-cholest-7-ene with a large excess (24 molar excess) of lithium aluminum hydride gave, in addition to the expected 5alpha-cholest-8(14)-en-3beta,15alpha-diol, a significant yield (33%) of 5alpha-cholest-8(14)-en-3beta-o1. Reduction of the epoxy ester with a large excess (24 molar excess) of lithium aluminum deuteride gave [7alpha-2H]-5alpha-cholest-8(14)-en-3beta,15alpha-diol and 5alpha-cholest-8(14)-en-3beta-o1 which contained two atoms of stably bound deuterium. PMID:858170

  7. Chemical repair activity of free radical scavenger edaravone: reduction reactions with dGMP hydroxyl radical adducts and suppression of base lesions and AP sites on irradiated plasmid DNA.

    PubMed

    Hata, Kuniki; Urushibara, Ayumi; Yamashita, Shinichi; Lin, Mingzhang; Muroya, Yusa; Shikazono, Naoya; Yokoya, Akinari; Fu, Haiying; Katsumura, Yosuke

    2015-01-01

    Reactions of edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one) with deoxyguanosine monophosphate (dGMP) hydroxyl radical adducts were investigated by pulse radiolysis technique. Edaravone was found to reduce the dGMP hydroxyl radical adducts through electron transfer reactions. The rate constants of the reactions were greater than 4 × 10(8) dm(3) mol(-1) s(-1) and similar to those of the reactions of ascorbic acid, which is a representative antioxidant. Yields of single-strand breaks, base lesions, and abasic sites produced in pUC18 plasmid DNA by gamma ray irradiation in the presence of low concentrations (10-1000 μmol dm(-3)) of edaravone were also quantified, and the chemical repair activity of edaravone was estimated by a method recently developed by the authors. By comparing suppression efficiencies to the induction of each DNA lesion, it was found that base lesions and abasic sites were suppressed by the chemical repair activity of edaravone, although the suppression of single-strand breaks was not very effective. This phenomenon was attributed to the chemical repair activity of edaravone toward base lesions and abasic sites. However, the chemical repair activity of edaravone for base lesions was lower than that of ascorbic acid.

  8. Interactions between Biological and Abiotic Pathways in the Reduction of Chlorinated Solvents

    EPA Science Inventory

    While biologically mediated reductive dechlorination continues to be a significant focus of chlorinated solvent remediation, there has been an increased interest in abiotic reductive processes for the remediation of chlorinated solvents. In situ chemical reduction (ISCR) uses zer...

  9. Dissimilatory perchlorate reduction: a review.

    PubMed

    Bardiya, Nirmala; Bae, Jae-Ho

    2011-05-20

    In the United States anthropogenic activities are mainly responsible for the wide spread perchlorate contamination of drinking water, surface water, groundwater, and soil. Even at microgram levels, perchlorate causes toxicity to flora and fauna and affects growth, metabolism and reproduction in humans and animals. Reports of antithyroid effects of perchlorate and its detection in common food items have raised serious public health concerns, leading to extensive decontamination efforts in recent years. Several physico-chemical removal and biological decontamination processes are being developed. Although promising, ion exchange is a non-selective and incomplete process as it merely transfers perchlorate from water to the resin. The perchlorate-laden spent resins (perchlorate 200-500 mg L(-1)) require regeneration resulting in production of concentrated brine (6-12% NaCl) or caustic waste streams. On the contrary, biological reduction completely degrades perchlorate into O(2) and innocuous Cl(-). High reduction potential of ClO(4)(-)/Cl(-) (E° =∼ 1.28 V) and ClO(3)(-)/Cl(-) pairs (E° =1.03 V) makes these contaminants thermodynamically ideal e(-) acceptors for microbial reduction. In recent years unique dissimilatory perchlorate reducing bacteria have been isolated and detailed studies pertaining to their microbiological, biochemical, genetics and phylogenetic aspects have been undertaken which is the subject of this review article while the various physico-chemical removal and biological reduction processes have been reviewed by others.

  10. Flavin reduction activates Drosophila cryptochrome

    PubMed Central

    Vaidya, Anand T.; Top, Deniz; Manahan, Craig C.; Tokuda, Joshua M.; Zhang, Sheng; Pollack, Lois; Young, Michael W.; Crane, Brian R.

    2013-01-01

    Entrainment of circadian rhythms in higher organisms relies on light-sensing proteins that communicate to cellular oscillators composed of delayed transcriptional feedback loops. The principal photoreceptor of the fly circadian clock, Drosophila cryptochrome (dCRY), contains a C-terminal tail (CTT) helix that binds beside a FAD cofactor and is essential for light signaling. Light reduces the dCRY FAD to an anionic semiquinone (ASQ) radical and increases CTT proteolytic susceptibility but does not lead to CTT chemical modification. Additional changes in proteolytic sensitivity and small-angle X-ray scattering define a conformational response of the protein to light that centers at the CTT but also involves regions remote from the flavin center. Reduction of the flavin is kinetically coupled to CTT rearrangement. Chemical reduction to either the ASQ or the fully reduced hydroquinone state produces the same conformational response as does light. The oscillator protein Timeless (TIM) contains a sequence similar to the CTT; the corresponding peptide binds dCRY in light and protects the flavin from oxidation. However, TIM mutants therein still undergo dCRY-mediated degradation. Thus, photoreduction to the ASQ releases the dCRY CTT and promotes binding to at least one region of TIM. Flavin reduction by either light or cellular reductants may be a general mechanism of CRY activation. PMID:24297896

  11. Lithium Ethylene Dicarbonate Identified as the Primary Product ofChemical and Electrochemical Reduction of EC in EC:EMC/1.2M LiPF6Electrolyte

    SciTech Connect

    Zhuang, Guorong V.; Xu, Kang; Yang, Hui; Jow, T. Richard; RossJr., Philip N.

    2005-05-11

    Lithium ethylene dicarbonate (CH2OCO2Li)2 was chemically synthesized and its Fourier Transform Infrared (FTIR) spectrum was obtained and compared with that of surface films formed on Ni after cyclic voltammetry (CV) in 1.2M lithium hexafluorophosphate(LiPF6)/ethylene carbonate (EC): ethyl methyl carbonate (EMC) (3:7, w/w) electrolyte and on metallic lithium cleaved in-situ in the same electrolyte. By comparison of IR experimental spectra with that of the synthesized compound, we established that the title compound is the predominant surface species in both instances. Detailed analysis of the IR spectrum utilizing quantum chemical (Hartree-Fock) calculations indicates that intermolecular association through O...Li...O interactions is very important in this compound. It is likely that the title compound in passivation layer has a highly associated structure, but the exact intermolecular conformation could not be established based on analysis of the IR spectrum.

  12. Dissolution and reduction of magnetite by bacteria

    NASA Technical Reports Server (NTRS)

    Kostka, J. E.; Nealson, K. H.

    1995-01-01

    Magnetite (Fe3O4) is an iron oxide of mixed oxidation state [Fe(II), Fe(III)] that contributes largely to geomagnetism and plays a significant role in diagenesis in marine and freshwater sediments. Magnetic data are the primary evidence for ocean floor spreading and accurate interpretation of the sedimentary magnetic record depends on an understanding of the conditions under which magnetite is stable. Though chemical reduction of magnetite by dissolved sulfide is well known, biological reduction has not been considered likely based upon thermodynamic considerations. This study shows that marine and freshwater strains of the bacterium Shewanella putrefaciens are capable of the rapid dissolution and reduction of magnetite, converting millimolar amounts to soluble Fe(II)in a few days at room temperature. Conditions under which magnetite reduction is optimal (pH 5-6, 22-37 degrees C) are consistent with an enzymatic process and not with simple chemical reduction. Magnetite reduction requires viable cells and cell contact, and it appears to be coupled to electron transport and growth. In a minimal medium with formate or lactate as the electron donor, more than 10 times the amount of magnetite was reduced over no carbon controls. These data suggest that magnetite reduction is coupled to carbon metabolism in S. putrefaciens. Bacterial reduction rates of magnetite are of the same order of magnitude as those estimated for reduction by sulfide. If such remobilization of magnetite occurs in nature, it could have a major impact on sediment magnetism and diagenesis.

  13. Dissolution and reduction of magnetite by bacteria.

    PubMed

    Kostka, J E; Nealson, K H

    1995-10-01

    Magnetite (Fe3O4) is an iron oxide of mixed oxidation state [Fe(II), Fe(III)] that contributes largely to geomagnetism and plays a significant role in diagenesis in marine and freshwater sediments. Magnetic data are the primary evidence for ocean floor spreading and accurate interpretation of the sedimentary magnetic record depends on an understanding of the conditions under which magnetite is stable. Though chemical reduction of magnetite by dissolved sulfide is well known, biological reduction has not been considered likely based upon thermodynamic considerations. This study shows that marine and freshwater strains of the bacterium Shewanella putrefaciens are capable of the rapid dissolution and reduction of magnetite, converting millimolar amounts to soluble Fe(II)in a few days at room temperature. Conditions under which magnetite reduction is optimal (pH 5-6, 22-37 degrees C) are consistent with an enzymatic process and not with simple chemical reduction. Magnetite reduction requires viable cells and cell contact, and it appears to be coupled to electron transport and growth. In a minimal medium with formate or lactate as the electron donor, more than 10 times the amount of magnetite was reduced over no carbon controls. These data suggest that magnetite reduction is coupled to carbon metabolism in S. putrefaciens. Bacterial reduction rates of magnetite are of the same order of magnitude as those estimated for reduction by sulfide. If such remobilization of magnetite occurs in nature, it could have a major impact on sediment magnetism and diagenesis. PMID:11539843

  14. Chemically rechargeable battery

    NASA Technical Reports Server (NTRS)

    Graf, James E. (Inventor); Rowlette, John J. (Inventor)

    1984-01-01

    Batteries (50) containing oxidized, discharged metal electrodes such as an iron-air battery are charged by removing and storing electrolyte in a reservoir (98), pumping fluid reductant such as formalin (aqueous formaldehyde) from a storage tank (106) into the battery in contact with the surfaces of the electrodes. After sufficient iron hydroxide has been reduced to iron, the spent reductant is drained, the electrodes rinsed with water from rinse tank (102) and then the electrolyte in the reservoir (106) is returned to the battery. The battery can be slowly electrically charged when in overnight storage but can be quickly charged in about 10 minutes by the chemical procedure of the invention.

  15. A Virtual Aluminum Reduction Cell

    NASA Astrophysics Data System (ADS)

    Zhang, Hongliang; Zhou, Chenn Q.; Wu, Bing; Li, Jie

    2013-11-01

    The most important component in the aluminum industry is the aluminum reduction cell; it has received considerable interests and resources to conduct research to improve its productivity and energy efficiency. The current study focused on the integration of numerical simulation data and virtual reality technology to create a scientifically and practically realistic virtual aluminum reduction cell by presenting complex cell structures and physical-chemical phenomena. The multiphysical field simulation models were first built and solved in ANSYS software (ANSYS Inc., Canonsburg, PA, USA). Then, the methodology of combining the simulation results with virtual reality was introduced, and a virtual aluminum reduction cell was created. The demonstration showed that a computer-based world could be created in which people who are not analysis experts can see the detailed cell structure in a context that they can understand easily. With the application of the virtual aluminum reduction cell, even people who are familiar with aluminum reduction cell operations can gain insights that make it possible to understand the root causes of observed problems and plan design changes in much less time.

  16. Chemical Reactors.

    ERIC Educational Resources Information Center

    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)

  17. Chemical sensor

    NASA Technical Reports Server (NTRS)

    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.

  18. [Chemical weapons and chemical terrorism].

    PubMed

    Nakamura, Katsumi

    2005-10-01

    Chemical Weapons are kind of Weapons of Mass Destruction (WMD). They were used large quantities in WWI. Historically, large quantities usage like WWI was not recorded, but small usage has appeared now and then. Chemical weapons are so called "Nuclear weapon for poor countrys" because it's very easy to produce/possession being possible. They are categorized (1) Nerve Agents, (2) Blister Agents, (3) Cyanide (blood) Agents, (4) Pulmonary Agents, (5) Incapacitating Agents (6) Tear Agents from the viewpoint of human body interaction. In 1997 the Chemical Weapons Convention has taken effect. It prohibits chemical weapons development/production, and Organization for the Prohibition of Chemical Weapons (OPCW) verification regime contributes to the chemical weapons disposal. But possibility of possession/use of weapons of mass destruction by terrorist group represented in one by Matsumoto and Tokyo Subway Sarin Attack, So new chemical terrorism countermeasures are necessary.

  19. Chemical microsensors

    DOEpatents

    Li, DeQuan; Swanson, Basil I.

    1995-01-01

    An article of manufacture is provided including a substrate having an oxide surface layer and a selective thin film of a cyclodextrin derivative chemically bound upon said substrate, said film is adapted for the inclusion of a selected organic compound therewith. Such an article can be either a chemical sensor capable of detecting a resultant mass change from inclusion of the selected organic compound or a chemical separator capable of reversibly selectively separating a selected organic compound.

  20. Drastic reduction in the surface recombination velocity of crystalline silicon passivated with catalytic chemical vapor deposited SiN{sub x} films by introducing phosphorous catalytic-doped layer

    SciTech Connect

    Thi, Trinh Cham Koyama, Koichi; Ohdaira, Keisuke; Matsumura, Hideki

    2014-07-28

    We improve the passivation property of n-type crystalline silicon (c-Si) surface passivated with a catalytic chemical vapor deposited (Cat-CVD) Si nitride (SiN{sub x}) film by inserting a phosphorous (P)-doped layer formed by exposing c-Si surface to P radicals generated by the catalytic cracking of PH{sub 3} molecules (Cat-doping). An extremely low surface recombination velocity (SRV) of 2 cm/s can be achieved for 2.5 Ω cm n-type (100) floating-zone Si wafers passivated with SiN{sub x}/P Cat-doped layers, both prepared in Cat-CVD systems. Compared with the case of only SiN{sub x} passivated layers, SRV decreases from 5 cm/s to 2 cm/s. The decrease in SRV is the result of field effect created by activated P atoms (donors) in a shallow P Cat-doped layer. Annealing process plays an important role in improving the passivation quality of SiN{sub x} films. The outstanding results obtained imply that SiN{sub x}/P Cat-doped layers can be used as promising passivation layers in high-efficiency n-type c-Si solar cells.

  1. MCNP variance reduction overview

    SciTech Connect

    Hendricks, J.S.; Booth, T.E.

    1985-01-01

    The MCNP code is rich in variance reduction features. Standard variance reduction methods found in most Monte Carlo codes are available as well as a number of methods unique to MCNP. We discuss the variance reduction features presently in MCNP as well as new ones under study for possible inclusion in future versions of the code.

  2. Chemical sensors

    DOEpatents

    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.

  3. Chemical Peels

    MedlinePlus

    ... the complications or potential side effects of a chemical peel? Temporary or permanent change in skin color, particularly for women on birth control pills, who subsequently become pregnant or have a history of brownish facial ... after having a chemical peel? All peels require some follow-up care: ...

  4. Chemical preconcentrator

    DOEpatents

    Manginell, Ronald P.; Frye-Mason, Gregory C.

    2001-01-01

    A chemical preconcentrator is disclosed with applications to chemical sensing and analysis. The preconcentrator can be formed by depositing a resistive heating element (e.g. platinum) over a membrane (e.g. silicon nitride) suspended above a substrate. A coating of a sorptive material (e.g. a microporous hydrophobic sol-gel coating or a polymer coating) is formed on the suspended membrane proximate to the heating element to selective sorb one or more chemical species of interest over a time period, thereby concentrating the chemical species in the sorptive material. Upon heating the sorptive material with the resistive heating element, the sorbed chemical species are released for detection and analysis in a relatively high concentration and over a relatively short time period. The sorptive material can be made to selectively sorb particular chemical species of interest while not substantially sorbing other chemical species not of interest. The present invention has applications for use in forming high-sensitivity, rapid-response miniaturized chemical analysis systems (e.g. a "chem lab on a chip").

  5. Chemical sensors

    DOEpatents

    Lowell, Jr., James R.; Edlund, David J.; Friesen, Dwayne T.; Rayfield, George W.

    1991-01-01

    Sensors responsive to small changes in the concentration of chemical species are disclosed, comprising (a) a mechanochemically responsive polymeric film capable of expansion or contraction in response to a change in its chemical environment, operatively coupled to (b) a transducer capable of directly converting said expansion or contraction to a measurable electrical response.

  6. Chemical Emergencies

    MedlinePlus

    ... agents such as sarin and VX. Many hazardous chemicals are used in industry - for example, chlorine, ammonia, and benzene. Some can be made from everyday items such as household cleaners. Although there are no guarantees of safety during a chemical emergency, you can take actions to protect yourself. ...

  7. Chemical threats.

    PubMed

    Fry, Donald E

    2006-06-01

    The use of chemical agents as military weapons has been recognized for many centuries but reached the most feared and publicized level during World War I. Considerable political effort has been exercised in the twentieth century to restrict military strategies with chemicals. However, considerable concern currently exists that chemical weapons may be used as agents in civilian terrorism. The distribution of acetaminophen tablets contaminated with potassium cyanide and the release of sarin in the Tokyo sub-way system show that larger-scale deployment of chemical agents can be a reality. This reality makes it necessary for civilian disaster-planning strategies to incorporate an understanding of chemical agents, their effects, and the necessary treatment.

  8. Optimizing parallel reduction operations

    SciTech Connect

    Denton, S.M.

    1995-06-01

    A parallel program consists of sets of concurrent and sequential tasks. Often, a reduction (such as array sum) sequentially combines values produced by a parallel computation. Because reductions occur so frequently in otherwise parallel programs, they are good candidates for optimization. Since reductions may introduce dependencies, most languages separate computation and reduction. The Sisal functional language is unique in that reduction is a natural consequence of loop expressions; the parallelism is implicit in the language. Unfortunately, the original language supports only seven reduction operations. To generalize these expressions, the Sisal 90 definition adds user-defined reductions at the language level. Applicable optimizations depend upon the mathematical properties of the reduction. Compilation and execution speed, synchronization overhead, memory use and maximum size influence the final implementation. This paper (1) Defines reduction syntax and compares with traditional concurrent methods; (2) Defines classes of reduction operations; (3) Develops analysis of classes for optimized concurrency; (4) Incorporates reductions into Sisal 1.2 and Sisal 90; (5) Evaluates performance and size of the implementations.

  9. Regeneration of anion exchange resins by catalyzed electrochemical reduction

    DOEpatents

    Gu, Baohua; Brown, Gilbert M.

    2002-01-01

    Anion exchange resins sorbed with perchlorate may be regenerated by a combination of chemical reduction of perchlorate to chloride using a reducing agent and an electrochemical reduction of the oxidized reducing agent. Transitional metals including Ti, Re, and V are preferred chemical reagents for the reduction of perchlorate to chloride. Complexing agents such as oxalate are used to prevent the precipitation of the oxidized Ti(IV) species, and ethyl alcohol may be added to accelerate the reduction kinetics of perchlorate. The regeneration may be performed by continuously recycling the regenerating solution through the resin bed and an electrochemical cell so that the secondary waste generation is minimized.

  10. Cost Reduction Incentive Awards. 1981 Winners.

    ERIC Educational Resources Information Center

    National Association of College and University Business Officers, Washington, DC.

    Brief descriptions of 47 college programs recognized for awards in the National Association of College and University Officers/U. S. Steel Foundation Cost Reduction Incentive Awards Program are given. They include awards for: shower stall repair; chemical waste exchange; vibrating alarms for hearing-imparied; self-funding insurance consortium;…

  11. Chemical simulation of greywater.

    PubMed

    Abed, Suhail Najem; Scholz, Miklas

    2016-01-01

    Sustainable water resources management attracts considerable attention in today's world. Recycling and reuse of both wastewater and greywater are becoming more attractive. The strategy is to protect ecosystem services by balancing the withdrawal of water and the disposal of wastewater. In the present study, a timely and novel synthetic greywater composition has been proposed with respect to the composition of heavy metals, nutrients and organic matter. The change in water quality of the synthetic greywater due to increasing storage time was monitored to evaluate the stability of the proposed chemical formula. The new greywater is prepared artificially using analytical-grade chemicals to simulate either low (LC) or high (HC) pollutant concentrations. The characteristics of the synthetic greywater were tested (just before starting the experiment, after two days and a week of storage under real weather conditions) and compared to those reported for real greywater. Test results for both synthetic greywater types showed great similarities with the physiochemical properties of published findings concerning real greywater. Furthermore, the synthetic greywater is relatively stable in terms of its characteristics for different storage periods. However, there was a significant (p < .05) reduction in 5-day biochemical oxygen demand (BOD5) for both low (LC) and high (HC) concentrations of greywater after two days of storage with reductions of 62% and 55%, respectively. A significant (p < .05) change was also noted for the reduction (70%) of nitrate-nitrogen (NO3-N) concerning HC greywater after seven days of storage. PMID:26745659

  12. Chemical simulation of greywater.

    PubMed

    Abed, Suhail Najem; Scholz, Miklas

    2016-01-01

    Sustainable water resources management attracts considerable attention in today's world. Recycling and reuse of both wastewater and greywater are becoming more attractive. The strategy is to protect ecosystem services by balancing the withdrawal of water and the disposal of wastewater. In the present study, a timely and novel synthetic greywater composition has been proposed with respect to the composition of heavy metals, nutrients and organic matter. The change in water quality of the synthetic greywater due to increasing storage time was monitored to evaluate the stability of the proposed chemical formula. The new greywater is prepared artificially using analytical-grade chemicals to simulate either low (LC) or high (HC) pollutant concentrations. The characteristics of the synthetic greywater were tested (just before starting the experiment, after two days and a week of storage under real weather conditions) and compared to those reported for real greywater. Test results for both synthetic greywater types showed great similarities with the physiochemical properties of published findings concerning real greywater. Furthermore, the synthetic greywater is relatively stable in terms of its characteristics for different storage periods. However, there was a significant (p < .05) reduction in 5-day biochemical oxygen demand (BOD5) for both low (LC) and high (HC) concentrations of greywater after two days of storage with reductions of 62% and 55%, respectively. A significant (p < .05) change was also noted for the reduction (70%) of nitrate-nitrogen (NO3-N) concerning HC greywater after seven days of storage.

  13. Chemical peeling.

    PubMed

    Forte, R; Hack, J; Jackson, I T

    1993-01-01

    This article explores the wide range of chemical facial peels, which include phenol, trichloroacetic acid, and alpha-hydroxy acids. The application of these substances will be described in addition to the contraindications to this type of treatment.

  14. Unnecessary Chemicals

    ERIC Educational Resources Information Center

    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)

  15. Chemical sensors

    DOEpatents

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

    1992-06-09

    Sensors responsive to small changes in the concentration of chemical species are disclosed, comprising a mechanicochemically responsive polymeric film capable of expansion or contraction in response to a change in its chemical environment, either operatively coupled to a transducer capable of directly converting the expansion or contraction to a measurable electrical or optical response, or adhered to a second inert polymeric strip, or doped with a conductive material. 12 figs.

  16. Chemical sensors

    DOEpatents

    Lowell, Jr., James R.; Edlund, David J.; Friesen, Dwayne T.; Rayfield, George W.

    1992-01-01

    Sensors responsive to small changes in the concentration of chemical species are disclosed, comprising a mechanicochemically responsive polymeric film capable of expansion or contraction in response to a change in its chemical environment, either operatively coupled to a transducer capable of directly converting the expansion or contraction to a measurable electrical or optical response, or adhered to a second inert polymeric strip, or doped with a conductive material.

  17. Chemical processing of lunar materials

    NASA Technical Reports Server (NTRS)

    Criswell, D. R.; Waldron, R. D.

    1979-01-01

    The paper highlights recent work on the general problem of processing lunar materials. The discussion covers lunar source materials, refined products, motivations for using lunar materials, and general considerations for a lunar or space processing plant. Attention is given to chemical processing through various techniques, including electrolysis of molten silicates, carbothermic/silicothermic reduction, carbo-chlorination process, NaOH basic-leach process, and HF acid-leach process. Several options for chemical processing of lunar materials are well within the state of the art of applied chemistry and chemical engineering to begin development based on the extensive knowledge of lunar materials.

  18. Collaborating for Multi-Scale Chemical Science

    SciTech Connect

    William H. Green

    2006-07-14

    Advanced model reduction methods were developed and integrated into the CMCS multiscale chemical science simulation software. The new technologies were used to simulate HCCI engines and burner flames with exceptional fidelity.

  19. Drag reduction in nature

    NASA Technical Reports Server (NTRS)

    Bushnell, D. M.; Moore, K. J.

    1991-01-01

    Recent studies on the drag-reducing shapes, structures, and behaviors of swimming and flying animals are reviewed, with an emphasis on potential analogs in vehicle design. Consideration is given to form drag reduction (turbulent flow, vortex generation, mass transfer, and adaptations for body-intersection regions), skin-friction drag reduction (polymers, surfactants, and bubbles as surface 'additives'), reduction of the drag due to lift, drag-reduction studies on porpoises, and drag-reducing animal behavior (e.g., leaping out of the water by porpoises). The need for further research is stressed.

  20. 75 FR 60430 - Federal Advisory Committee; Threat Reduction Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-30

    ... technology security, combating weapons of mass destruction (WMD), chemical and biological defense, the future... level briefings on WMD threats, the Defense Threat Reduction Agency, and the status of the...

  1. 40 CFR 716.50 - Reporting physical and chemical properties.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Reporting physical and chemical... chemical properties. Studies of physical and chemical properties must be reported under this subpart if...) Degradation by chemical mechanisms—hydrolytic, reductive, and oxidative. (j) Degradation by...

  2. Chemical sensors

    SciTech Connect

    Hubbard, C.W.; Gordon, R.L.

    1987-05-01

    The revolution in analytical chemistry promised by recent developments in the field of chemical sensors has potential for significant positive impact on both research and production activities conducted by and for the Department of Energy. Analyses which were, in the past, performed only with a roomful of expensive equipment can now be performed with miniature solid-state electronic devices or small optical probes. Progress in the development of chemical sensors has been rapid, and the field is currently growing at a great rate. In accordance, Pacific Northwest Laboratory initiated a survey of recent literature so that contributors to active programs in research on analytical methods could be made aware of principles and applications of this new technology. This report presents the results of that survey. The sensors discussed here are divided into three types: micro solid-state devices, optical sensors, and piezoelectric crystal devices. The report is divided into three corresponding sections. The first section, ''Micro Solid-State Devices,'' discusses the design, operation, and application of electronic sensors that are produced in much the same way as standard solid-state electronic devices. The second section, ''Optrodes,'' covers the design and operation of chemical sensors that use fiber optics to detect chemically induced changes in optical properties. The final section, ''Piezoelectric Crystal Detectors,'' discusses two types of chemical sensors that depend on the changes in the properties of an oscillating piezoelectric crystal to detect the presence of certain materials. Advantages and disadvantages of each type of sensor are summarized in each section.

  3. Lithium metal reduction of plutonium oxide to produce plutonium metal

    DOEpatents

    Coops, Melvin S.

    1992-01-01

    A method is described for the chemical reduction of plutonium oxides to plutonium metal by the use of pure lithium metal. Lithium metal is used to reduce plutonium oxide to alpha plutonium metal (alpha-Pu). The lithium oxide by-product is reclaimed by sublimation and converted to the chloride salt, and after electrolysis, is removed as lithium metal. Zinc may be used as a solvent metal to improve thermodynamics of the reduction reaction at lower temperatures. Lithium metal reduction enables plutonium oxide reduction without the production of huge quantities of CaO--CaCl.sub.2 residues normally produced in conventional direct oxide reduction processes.

  4. Chemical networks

    NASA Astrophysics Data System (ADS)

    Thi, Wing-Fai

    2015-09-01

    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 on-going research subject is finding new paths to synthesize species either in the gas-phase or on grain surfaces. Specific formation routes for water or carbon monoxide are discussed in more details. 13th Lecture of the Summer School "Protoplanetary Disks: Theory and Modelling Meet Observations"

  5. Principles of harm reduction. Harm Reduction Coalition.

    PubMed

    1998-06-01

    Harm reduction is a set of practical strategies used for working with drug users to help them choose behaviors that are less risky. The harm reduction approach accepts that illicit drug use occurs, and encourages input from drug users in designing programs and services to help educate themselves. Drug use is a complex problem related to poverty, class, racism, social isolation, and discrimination, and calls for non-judgmental, non-coercive services for the drug using population. Federal money for drug interventions is more often spent on incarcerations and prosecutions, than on education, research, prevention, or treatment. Public policy changes, such as teaching drug users how to lower their risks, may reduce the number of deaths and HIV transmissions among drug users and their partners.

  6. Microbial reductive dehalogenation.

    PubMed Central

    Mohn, W W; Tiedje, J M

    1992-01-01

    A wide variety of compounds can be biodegraded via reductive removal of halogen substituents. This process can degrade toxic pollutants, some of which are not known to be biodegraded by any other means. Reductive dehalogenation of aromatic compounds has been found primarily in undefined, syntrophic anaerobic communities. We discuss ecological and physiological principles which appear to be important in these communities and evaluate how widely applicable these principles are. Anaerobic communities that catalyze reductive dehalogenation appear to differ in many respects. A large number of pure cultures which catalyze reductive dehalogenation of aliphatic compounds are known, in contrast to only a few organisms which catalyze reductive dehalogenation of aromatic compounds. Desulfomonile tiedjei DCB-1 is an anaerobe which dehalogenates aromatic compounds and is physiologically and morphologically unusual in a number of respects, including the ability to exploit reductive dehalogenation for energy metabolism. When possible, we use D. tiedjei as a model to understand dehalogenating organisms in the above-mentioned undefined systems. Aerobes use reductive dehalogenation for substrates which are resistant to known mechanisms of oxidative attack. Reductive dehalogenation, especially of aliphatic compounds, has recently been found in cell-free systems. These systems give us an insight into how and why microorganisms catalyze this activity. In some cases transition metal complexes serve as catalysts, whereas in other cases, particularly with aromatic substrates, the catalysts appear to be enzymes. Images PMID:1406492

  7. Intelligent Data Reduction (IDARE)

    NASA Technical Reports Server (NTRS)

    Brady, D. Michael; Ford, Donnie R.

    1990-01-01

    A description of the Intelligent Data Reduction (IDARE) expert system and an IDARE user's manual are given. IDARE is a data reduction system with the addition of a user profile infrastructure. The system was tested on a nickel-cadmium battery testbed. Information is given on installing, loading, maintaining the IDARE system.

  8. Reduction of Dissolved Oxygen at a Copper Rotating Disc Electrode

    ERIC Educational Resources Information Center

    Kear, Gareth; Albarran, Carlos Ponce-de-Leon; Walsh, Frank C.

    2005-01-01

    Undergraduates from chemical engineering, applied chemistry, and environmental science courses, together with first-year postgraduate research students in electrochemical technology, are provided with an experiment that demonstrates the reduction of dissolved oxygen in aerated seawater at 25°C. Oxygen reduction is examined using linear sweep…

  9. Pathogen reduction in human plasma using an ultrashort pulsed laser

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pathogen reduction is an ideal approach to ensure the continued safety of the blood supply against emerging pathogens. However, the currently licensed pathogen reduction techniques are ineffective against non-enveloped viruses, and they introduce chemicals with concerns of side effects which prevent...

  10. INCORPORATING ENVIRONMENTAL AND ECONOMIC CONSIDERATIONS INTO PROCESS DESIGN: THE WASTE REDUCTION (WAR) ALGORITHM

    EPA Science Inventory

    A general theory known as the WAste Reduction (WASR) algorithm has been developed to describe the flow and the generation of potential environmental impact through a chemical process. This theory integrates environmental impact assessment into chemical process design Potential en...

  11. WORKSHOP ON MONITORING OXIDATION-REDUCTION PROCESSES FOR GROUND-WATER RESTORATION

    EPA Science Inventory

    Redox conditions are among the most important parameters for controlling contaminant transport and fate in ground-water systems. Oxidation-reduction (redox) reactions mediate the chemical behavior of both inorganic and organic chemical constituents by affecting solubility, rea...

  12. Chemical Mahjong

    ERIC Educational Resources Information Center

    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…

  13. Delicious Chemicals.

    ERIC Educational Resources Information Center

    Barry, Dana M.

    This paper presents an approach to chemistry and nutrition that focuses on food items that people consider delicious. Information is organized according to three categories of food chemicals that provide energy to the human body: (1) fats and oils; (2) carbohydrates; and (3) proteins. Minerals, vitamins, and additives are also discussed along with…

  14. Chemical Indicators.

    ERIC Educational Resources Information Center

    Prombain, Dorothy R.; And Others

    This science sourcebook was written for intermediate grade teachers to provide guidance in teaching a specially developed unit on chemical indicators. Directions and suggestions for guiding student science activities are given. Some of the activities concern soil testing, crystals, and household powders such as sugar and salt. A list of necessary…

  15. Chemical Education Conference Caters to Varied Audience.

    ERIC Educational Resources Information Center

    Worthy, Ward

    1986-01-01

    Reports on the 9th Biennial Conference on Chemical Education sponsored by the American Chemical Society. The conference theme: "Chemistry: Learning, Instructing, Presenting," was addressed by numerous sessions. Highlighted were presentations calling for an increase in process-oriented chemistry teaching, reduction of "science anxiety," and the…

  16. Microbial reduction of uranium

    USGS Publications Warehouse

    Lovley, D.R.; Phillips, E.J.P.; Gorby, Y.A.; Landa, E.R.

    1991-01-01

    REDUCTION of the soluble, oxidized form of uranium, U(VI), to insoluble U(IV) is an important mechanism for the immobilization of uranium in aquatic sediments and for the formation of some uranium ores1-10. U(VI) reduction has generally been regarded as an abiological reaction in which sulphide, molecular hydrogen or organic compounds function as the reductant1,2,5,11. Microbial involvement in U(VI) reduction has been considered to be limited to indirect effects, such as microbial metabolism providing the reduced compounds for abiological U(VI) reduction and microbial cell walls providing a surface to stimulate abiological U(VI) reduction1,12,13. We report here, however, that dissimilatory Fe(III)-reducing microorganisms can obtain energy for growth by electron transport to U(VI). This novel form of microbial metabolism can be much faster than commonly cited abiological mechanisms for U(VI) reduction. Not only do these findings expand the known potential terminal electron acceptors for microbial energy transduction, they offer a likely explanation for the deposition of uranium in aquatic sediments and aquifers, and suggest a method for biological remediation of environments contaminated with uranium.

  17. Chemical reduction of phosphate on the primitive earth.

    PubMed

    Glindemann, D; De Graaf, R M; Schwartz, A W

    1999-12-01

    If phosphorus played a role in the origin of life, some means of concentrating micromolar levels of phosphate (derived from the calcium phosphate mineral apatite), must first have been available. Here we show that simulated (mini)lightning discharges in model prebiotic atmospheres, including only minimally reducing ones, reduce orthophosphates, including apatite, to produce substantial yields of phosphite. Electrical discharges associated with volcanic eruptions could have provided a particularly suitable environment for this process. Production of relatively soluble and reactive phosphite salts could have supplied a pathway by which the first phosphorus atoms were incorporated into (pre)biological systems. PMID:10666740

  18. Ultralow Level Mercury Treatment Using Chemical Reduction and Air Stripping

    SciTech Connect

    Looney, B.B.

    2001-02-23

    The overall objective of this work is to develop a reasonable and cost-effective approach to meet the emerging mercury standards, especially for high volume outfalls with concentrations below the drinking water standard.

  19. Large Scale Reduction of Graphite Oxide Project

    NASA Technical Reports Server (NTRS)

    Calle, Carlos; Mackey, Paul; Falker, John; Zeitlin, Nancy

    2015-01-01

    This project seeks to develop an optical method to reduce graphite oxide into graphene efficiently and in larger formats than currently available. Current reduction methods are expensive, time-consuming or restricted to small, limited formats. Graphene has potential uses in ultracapacitors, energy storage, solar cells, flexible and light-weight circuits, touch screens, and chemical sensors. In addition, graphite oxide is a sustainable material that can be produced from any form of carbon, making this method environmentally friendly and adaptable for in-situ reduction.

  20. Reduction of astrometric plates

    NASA Technical Reports Server (NTRS)

    Stock, J.

    1984-01-01

    A rapid and accurate method for the reduction of comet or asteroid plates is described. Projection equations, scale length correction, rotation of coordinates, linearization, the search for additional reference stars, and the final solution are examined.

  1. Active noise reduction

    NASA Astrophysics Data System (ADS)

    Carter, J.

    1984-01-01

    Active Noise Reduction (ANR) techniques, singly and in combination with passive hearing protectors, offer the potential for increased sound protection, enhanced voice communications and improved wearability features for personnel exposed to unacceptable noise conditions. An enhanced closed loop active noise reduction system was miniaturized and incorporated into a standard Air Force flight helmet (HGU-26/P). This report describes the theory of design and operation, prototype configuration and operation, and electroacoustic performance and specifications for the ANR system. This system is theoretically capable of producing in excess of 30 decibels of active noise reduction. Electroacoustic measurements on a flat plate coupler demonstrated approximately 20 decibels of active noise reduction with the prototype unit. A performance evaluation of the integrated ANR unit will be conducted under laboratory and field conditions by government personnel to determine the feasibility of the system for use in military applications.

  2. Quantization of Algebraic Reduction

    SciTech Connect

    Sniatycki, Jeodrzej

    2007-11-14

    For a Poisson algebra obtained by algebraic reduction of symmetries of a quantizable system we develop an analogue of geometric quantization based on the quantization structure of the original system.

  3. Experimental reduction of lunar mare soil and volcanic glass

    NASA Technical Reports Server (NTRS)

    Allen, Carlton C.; Morris, Richard V.; Mckay, David S.

    1994-01-01

    We have reduced high-titanium lunar mare soil and iron-rich lunar volcanic glass with hydrogen at temperatures of 900-1100 C. Ilmenite is the most reactive phase in the soil, exhibiting rapid and complete reduction at all temperatures. Ferrous iron in the glass is extensively reduced concurrent with partial crystallization. In both samples pyroxene and olivine undergo partial reduction along with chemical and mineralogical modifications. High-temperature reduction provides insight into the optical and chemical effects of lunar soil maturation, and places constraints on models of that process. Mare soil and volcanic glass are attractive feedstocks for lunar oxygen production, with achievable yields of 2-5 wt%.

  4. Structural basis of enzymatic benzene ring reduction.

    PubMed

    Weinert, Tobias; Huwiler, Simona G; Kung, Johannes W; Weidenweber, Sina; Hellwig, Petra; Stärk, Hans-Joachim; Biskup, Till; Weber, Stefan; Cotelesage, Julien J H; George, Graham N; Ermler, Ulrich; Boll, Matthias

    2015-08-01

    In chemical synthesis, the widely used Birch reduction of aromatic compounds to cyclic dienes requires alkali metals in ammonia as extremely low-potential electron donors. An analogous reaction is catalyzed by benzoyl-coenzyme A reductases (BCRs) that have a key role in the globally important bacterial degradation of aromatic compounds at anoxic sites. Because of the lack of structural information, the catalytic mechanism of enzymatic benzene ring reduction remained obscure. Here, we present the structural characterization of a dearomatizing BCR containing an unprecedented tungsten cofactor that transfers electrons to the benzene ring in an aprotic cavity. Substrate binding induces proton transfer from the bulk solvent to the active site by expelling a Zn(2+) that is crucial for active site encapsulation. Our results shed light on the structural basis of an electron transfer process at the negative redox potential limit in biology. They open the door for biological or biomimetic alternatives to a basic chemical synthetic tool.

  5. Pathogen reduction in human plasma using an ultrashort pulsed laser.

    PubMed

    Tsen, Shaw-Wei D; Kingsley, David H; Kibler, Karen; Jacobs, Bert; Sizemore, Sara; Vaiana, Sara M; Anderson, Jeanne; Tsen, Kong-Thon; Achilefu, Samuel

    2014-01-01

    Pathogen reduction is a viable approach to ensure the continued safety of the blood supply against emerging pathogens. However, the currently licensed pathogen reduction techniques are ineffective against non-enveloped viruses such as hepatitis A virus, and they introduce chemicals with concerns of side effects which prevent their widespread use. In this report, we demonstrate the inactivation of both enveloped and non-enveloped viruses in human plasma using a novel chemical-free method, a visible ultrashort pulsed laser. We found that laser treatment resulted in 2-log, 1-log, and 3-log reductions in human immunodeficiency virus, hepatitis A virus, and murine cytomegalovirus in human plasma, respectively. Laser-treated plasma showed ≥70% retention for most coagulation factors tested. Furthermore, laser treatment did not alter the structure of a model coagulation factor, fibrinogen. Ultrashort pulsed lasers are a promising new method for chemical-free, broad-spectrum pathogen reduction in human plasma.

  6. Physical chemistry of carbothermic reduction of alumina

    SciTech Connect

    Frank, Robert A.

    1985-09-01

    Production of aluminium, by means of carbothermic reduction of alumina, is discussed. By employing a solvent metal bath to absorb the alumina metal, carbothermic reduction of alumina was accomplished at temperatures 300/degree/C lower than the temperatures reported in the literature. Reduction occurred without the formation of intermediate compounds and without the high volatilization of aluminum bearing species. Reduction of alumina immersed in a solvent bath appeared to be rate limited by chemical reaction control. The rates seemed to be a function of the activity of aluminum in the solvent metal bath. Reduction of alumina particles, above the surface of the bath, seemed to occur via vapor transport with carbon in the particles or in the crucible walls. Mass transport in the gas phase appeared to be rate limiting. The rates seemed to be a function of the distance separating the alumina and carbon sources. With both submerged alumina and alumina particles, increasing the surface area of the alumina increased the rate of reduction. 58 refs., 65 figs., 9 tabs.

  7. Decontamination of metals using chemical etching

    DOEpatents

    Lerch, Ronald E.; Partridge, Jerry A.

    1980-01-01

    The invention relates to chemical etching process for reclaiming contaminated equipment wherein a reduction-oxidation system is included in a solution of nitric acid to contact the metal to be decontaminated and effect reduction of the reduction-oxidation system, and includes disposing a pair of electrodes in the reduced solution to permit passage of an electrical current between said electrodes and effect oxidation of the reduction-oxidation system to thereby regenerate the solution and provide decontaminated equipment that is essentially radioactive contamination-free.

  8. Method for producing chemical energy

    DOEpatents

    Jorgensen, Betty S.; Danen, Wayne C.

    2004-09-21

    Fluoroalkylsilane-coated metal particles having a central metal core, a buffer layer surrounding the core, and a fluoroalkylsilane layer attached to the buffer layer are prepared by combining a chemically reactive fluoroalkylsilane compound with an oxide coated metal particle having a hydroxylated surface. The resulting fluoroalkylsilane layer that coats the particles provides them with excellent resistance to aging. The particles can be blended with oxidant particles to form energetic powder that releases chemical energy when the buffer layer is physically disrupted so that the reductant metal core can react with the oxidant.

  9. Industrial Waste Reduction Program. Program plan

    SciTech Connect

    Not Available

    1991-10-24

    US industry generates over 12 billion tons of wastes each year. These wastes consist of undesirable by-products of industrial production that are discarded into our environment. Energy is an integral part of these wastes; it is found in the embodied energy of industrial feedstocks not optimally used, in the energy content of the wastes themselves, and in the energy needed to transport, treat, and dispose of wastes. Estimates of the potential energy savings from reducing industrial wastes range from three to four quadrillion Btu per year -- enough to meet the annual energy needs of 30 million American homes. This document presents a plan for the Industrial Waste Reduction Program, which has been designed to help achieve national goals for energy efficiency and waste minimization. The objective of the program is to improve the energy efficiency of industrial processes through cost-effective waste reduction. The initial program focus is on waste reduction opportunities in the production and use of chemicals, due to the significant amount of energy used in these activities and the large amounts of hazardous and toxic wastes they generate. The chemical industry will be the initial subject of a series of waste reduction opportunity assessments conducted as part of the program. Assessments of other industries and waste problems will follow.

  10. AMBER data reduction

    NASA Astrophysics Data System (ADS)

    Tatulli, E.; Duvert, G.

    2007-10-01

    This course describes the data reduction process of the AMBER instrument, the three beam-recombiner of the very large telescope interferometer (VLTI). In body of this paper, we develop its principles from a theoretical point of view and we illustrate the main points with examples taken from the practical AMBER data reduction session given during school. The detailed practical application making use of the ESO gasgano tool is then presented. In this lecture, we particularly emphasize what the AMBER data reduction process is (i) a fit of the interferogram in the detector plane, (ii) using an a priori calibration of the instrument, where (iii) the complex visibility of the source is estimated from a least-square determination of a linear inverse problem, and where (iv) the derived AMBER observables are the squared visibility, the closure phase, and the spectral differential phase.

  11. Protecting reproductive health and the environment: toxics use reduction.

    PubMed Central

    Geiser, K

    1993-01-01

    Toxics use reduction is a new chemical hazard management approach that has emerged in several state laws over the past years. While toxics use reduction has been promoted as a means of preventing environmental pollution, little thought has been given to its adoption as a means of managing reproductive hazards. This paper provides illustrations of use reduction approaches to conventionally recognized reproductive and developmental toxicants. These approaches will require the opening of a new dialogue between industrial designers and process managers and those most concerned about reproductive health. Several different strategies are proposed that might be adopted into state programs for promoting reduction in the use of reproductive and developmental toxicants. PMID:8243394

  12. Delay reduction: current status.

    PubMed

    Fantino, E; Preston, R A; Dunn, R

    1993-07-01

    Delay-reduction theory states that the effectiveness of a stimulus as a conditioned reinforcer may be predicted most accurately by the reduction in time to primary reinforcement correlated with its onset. We review support for the theory and then discuss two new types of experiments that assess it. One compares models of choice in situations wherein the less preferred outcome is made more accessible; the other investigates whether frequency of conditioned reinforcement affects choice beyond the effect exerted by frequency of primary reinforcement.

  13. REDUCTIONS WITHOUT REGRET: SUMMARY

    SciTech Connect

    Swegle, J.; Tincher, D.

    2013-09-16

    This paper briefly summarizes the series in which we consider the possibilities for losing, or compromising, key capabilities of the U.S. nuclear force in the face of modernization and reductions. The first of the three papers takes an historical perspective, considering capabilities that were eliminated in past force reductions. The second paper is our attempt to define the needed capabilities looking forward in the context of the current framework for force modernization and the current picture of the evolving challenges of deterrence and assurance. The third paper then provides an example for each of our undesirable outcomes: the creation of roach motels, box canyons, and wrong turns.

  14. Discrete reductive perturbation technique

    SciTech Connect

    Levi, Decio; Petrera, Matteo

    2006-04-15

    We expand a partial difference equation (P{delta}E) on multiple lattices and obtain the P{delta}E which governs its far field behavior. The perturbative-reductive approach is here performed on well-known nonlinear P{delta}Es, both integrable and nonintegrable. We study the cases of the lattice modified Korteweg-de Vries (mKdV) equation, the Hietarinta equation, the lattice Volterra-Kac-Van Moerbeke equation and a nonintegrable lattice KdV equation. Such reductions allow us to obtain many new P{delta}Es of the nonlinear Schroedinger type.

  15. Chemical locomotion.

    PubMed

    Paxton, Walter F; Sundararajan, Shakuntala; Mallouk, Thomas E; Sen, Ayusman

    2006-08-18

    Research into the autonomous motion of artificial nano- and microscale objects provides basic principles to explore possible applications, such as self-assembly of superstructures, roving sensors, and drug delivery. Although the systems described have unique propulsion mechanisms, motility in each case is made possible by the conversion of locally available chemical energy into mechanical energy. The use of catalysts onboard can afford nondissipative systems that are capable of directed motion. Key to the design of nano- and micromotors is the asymmetric placement of the catalyst: its placement in an environment containing a suitable substrate translates into non-uniform consumption of the substrate and distribution of reaction products, which results in the motility of the object. These same principles are exploited in nature to effect autonomous motion.

  16. Financing Class Size Reduction

    ERIC Educational Resources Information Center

    Achilles, C. M.

    2005-01-01

    Class size reduction has been shown to, among other things, improve academic achievement for all students and particularly for low-income and minority students. With the No Child Left Behind Act's heavy emphasis on scientifically based research, adequate yearly progress, and disaggregated results, one wonders why all children aren't enrolled in…

  17. Propulsion system noise reduction

    NASA Technical Reports Server (NTRS)

    Feiler, C. E.; Heidelberg, L. J.; Karchmer, A. M.; Lansing, D. L.; Miller, B. A.; Rice, E. J.

    1975-01-01

    The progress in propulsion system noise reduction is reviewed. The noise technology areas discussed include: fan noise; advances in suppression including conventional acoustic treatment, high Mach number inlets, and wing shielding; engine core noise; flap noise from both under-the-wing and over-the-wing powered-lift systems; supersonic jet noise suppression; and the NASA program in noise prediction.

  18. Exercise and Fat Reduction.

    ERIC Educational Resources Information Center

    Clarke, H. Harrison, Ed.

    1975-01-01

    This document analyzes the problems encountered by the obese individual and the effects of regular exercise on weight loss and fat reduction. Part one compares the psychological traits of obese children with age groups of normal weight and discusses the organic disorders and social attitudes which plague the overweight individual. Part two states…

  19. Imino Transfer Hydrogenation Reductions.

    PubMed

    Wills, Martin

    2016-04-01

    This review contains a summary of recent developments in the transfer hydrogenation of C=N bonds, with a particularly focus on reports from within the last 10 years and asymmetric transformations. However, earlier work in the area is also discussed in order to provide context for the more recent results described. I focus strongly on the Ru/TsDPEN class of asymmetric transfer hydrogenation reactions originally reported by Noyori et al., together with examples of their applications, particularly to medically valuable target molecules. The recent developments in the area of highly active imine-reduction catalysts, notably those based on iridium, are also described in some detail. I discuss diastereoselective reduction methods as a route to the synthesis of chiral amines using transfer hydrogenation. The recent development of a methodology for positioning reduction complexes within chiral proteins, permitting the generation of asymmetric reduction products through a directed modification of the protein environment in a controlled manner, is also discussed. PMID:27573139

  20. Nagel on reduction.

    PubMed

    Sarkar, Sahotra

    2015-10-01

    This paper attempts a critical reappraisal of Nagel's (1961, 1970) model of reduction taking into account both traditional criticisms and recent defenses. This model treats reduction as a type of explanation in which a reduced theory is explained by a reducing theory after their relevant representational items have been suitably connected. In accordance with the deductive-nomological model, the explanation is supposed to consist of a logical deduction. Nagel was a pluralist about both the logical form of the connections between the reduced and reducing theories (which could be conditionals or biconditionals) and their epistemological status (as analytic connections, conventions, or synthetic claims). This paper defends Nagel's pluralism on both counts and, in the process, argues that the multiple realizability objection to reductionism is misplaced. It also argues that the Nagel model correctly characterizes reduction as a type of explanation. However, it notes that logical deduction must be replaced by a broader class of inferential techniques that allow for different types of approximation. Whereas Nagel (1970), in contrast to his earlier position (1961), recognized the relevance of approximation, he did not realize its full import for the model. Throughout the paper two case studies are used to illustrate the arguments: the putative reduction of classical thermodynamics to the kinetic theory of matter and that of classical genetics to molecular biology.

  1. Intracellular chromium reduction.

    PubMed

    Arslan, P; Beltrame, M; Tomasi, A

    1987-10-22

    Two steps are involved in the uptake of Cr(VI): (1) the diffusion of the anion CrO4(2-) through a facilitated transport system, presumably the non-specific anion carrier and (2) the intracellular reduction of Cr(VI) to Cr(III). The intracellular reduction of Cr(VI), keeping the cytoplasmic concentration of Cr(VI) low, facilitates accumulation of chromate from extracellular medium into the cell. In the present paper, a direct demonstration of intracellular chromium reduction is provided by means of electron paramagnetic (spin) resonance (EPR) spectroscopy. Incubation of metabolically active rat thymocytes with chromate originates a signal which can be attributed to a paramagnetic species of chromium, Cr(V) or Cr(III). The EPR signal is originated by intracellular reduction of chromium since: (1) it is observed only when cells are incubated with chromate, (2) it is present even after extensive washings of the cells in a chromium-free medium; (3) it is abolished when cells are incubated with drugs able to reduce the glutathione pool, i.e., diethylmaleate or phorone; and (4) it is abolished when cells are incubated in the presence of a specific inhibitor of the anion carrier, 4-acetamido-4'-isothiocyanatostilbene-2-2'-disulfonic acid. PMID:2820507

  2. Nagel on reduction.

    PubMed

    Sarkar, Sahotra

    2015-10-01

    This paper attempts a critical reappraisal of Nagel's (1961, 1970) model of reduction taking into account both traditional criticisms and recent defenses. This model treats reduction as a type of explanation in which a reduced theory is explained by a reducing theory after their relevant representational items have been suitably connected. In accordance with the deductive-nomological model, the explanation is supposed to consist of a logical deduction. Nagel was a pluralist about both the logical form of the connections between the reduced and reducing theories (which could be conditionals or biconditionals) and their epistemological status (as analytic connections, conventions, or synthetic claims). This paper defends Nagel's pluralism on both counts and, in the process, argues that the multiple realizability objection to reductionism is misplaced. It also argues that the Nagel model correctly characterizes reduction as a type of explanation. However, it notes that logical deduction must be replaced by a broader class of inferential techniques that allow for different types of approximation. Whereas Nagel (1970), in contrast to his earlier position (1961), recognized the relevance of approximation, he did not realize its full import for the model. Throughout the paper two case studies are used to illustrate the arguments: the putative reduction of classical thermodynamics to the kinetic theory of matter and that of classical genetics to molecular biology. PMID:26386529

  3. Teaching Reductive Thinking

    ERIC Educational Resources Information Center

    Armoni, Michal; Gal-Ezer, Judith

    2005-01-01

    When dealing with a complex problem, solving it by reduction to simpler problems, or problems for which the solution is already known, is a common method in mathematics and other scientific disciplines, as in computer science and, specifically, in the field of computability. However, when teaching computational models (as part of computability)…

  4. Energy analysis of thermal, chemical, and metallurgical processes

    SciTech Connect

    Szargut, J.; Morris, D.R.; Steward, F.R.

    1988-01-01

    This book consists of the following chapters: The exergy concept and exergy losses; Calculation of exergy; Physical and chemical exergy of typical substances; Exergy analysis of typical thermal and chemical processes; Cumulative exergy consumption and cumulative degree of perfection; Reduction of external exergy losses; Exergy analysis of major thermal and chemical processes; Thermoeconomic applications of exergy; and Ecological applications of exergy.

  5. Chemical properties of mendelevium

    SciTech Connect

    Hulet, E.K.

    1980-11-01

    Even with the most intense ion beams and the largest available quantities of target isotope, about 10/sup 6/ atoms at a time is all the Md that can be produced for chemical studies. This lack of sufficient sample size coupled with the very short lifetimes of the few atoms produced has severely restricted the gathering and the broadness of our knowledge concerning the properties of Md and the heavier elements. To illustrate, the literature contains a mere eleven references to the chemical studies of Md, and none of these deal with bulk properties associated with the element bound in solid phases. Some of these findings are: Md was found to be more volatile than other actinide metals which lead to the belief that it is divalent in the metallic state; separation of Md from the other actinides can be accomplished either by reduction of Md/sup 3 +/ to the divalent state or by chromatographic separations with Md remaining in the tripositive state; extraction of Md/sup 2 +/ with bis(2-ethylhexyl)phosphoric acid is much poorer than the extraction of the neighboring tripositive actinides; attempts to oxidize Md/sup 3 +/ with sodium bismuthate failed to show any evidence for Md/sup 4 +/; reduction potential of Md/sup 3 +/ was found to be close to -0.1 volt; Md/sup 3 +/ can be reduced to Md(Hg) by sodium amalgams and by electrolysis; the electrochemical behavior of Md is very similar to that of Fm and can be summarized in the equation, Md/sup 2 +/ + 2e/sup -/ = Md(Hg) and E/sup 0/ = -1.50 V.; and Md cannot be reduced to a monovalent ion with Sm/sup 2 +/.

  6. Porosity reduction in Monterey Formation, California

    SciTech Connect

    Compton, J.S.

    1987-05-01

    Porosity and grain density were determined for different lithologies from throughout a 1.2-km thick section of the Monterey and Sisquoc formations in the Santa Maria basin area, California. Porosity reduction by physical and chemical compaction in the predominantly siliceous sediment is controlled largely by the bulk sediment composition and silica phase transformations. Physical compaction of sediment grains from increasing overburden pressure is responsible for most of the gradual porosity reduction with increasing burial depth in opal-A siliceous ooze and diatomite. The porous, incompressible diatom frustule maintains a high porosity relative to clayey and calcareous sediment. Therefore, a positive correlation exists between porosity and biogenic silica (diatom) content of the sediment. During the opal-A to opal-CT silica phase transformation, solution of the porous diatom frustule and precipitation of cryptocrystalline opal-CT results in a porosity reduction that roughly correlates with the biogenic silica content of the sediment. Local porosity reduction occurs in pore-filling dolomite and chert nodules. Dry bulk density as well as porosity reduction tend to increase with sediment depth. Dolomite and organic matter have the most significant influence on the bulk density because of their respective high and low density. The maximum burial depth of the uplifted and eroded section is estimated by overlapping the porosity-depth relation of average deep-sea siliceous ooze.

  7. Oxidation-reduction capacities of aquifer solids

    SciTech Connect

    Barcelona, M.J.; Holm, T.R.

    1991-01-01

    Oxidation-reduction processes play a major role in the mobility, transport, and fate of inorganic and organic chemical constituents in natural waters. Therefore, the manipulation of redox conditions in natural and treated water systems is assumed to be a common option for the control of contaminant concentrations. Measurements of the oxidation (i.e., of aqueous Cr(2+)) and reduction (i.e., of aqueous Cr2O7(2-) and H2O2) capacities of aquifer solids and groundwater have been made on samples from a sand-and-gravel aquifer. The groundwater contributed less than 1% of the system oxidation or reduction poising capacity. Reduction capacities averaged 0.095, 0.111, and 0.136 mequiv/g of dry solids for oxic, transitional, and reducing Eh conditions, respectively. Measured oxidation capacities averaged 0.4 mequiv/g of dry solids over the range of redox intensity conditions. These capacities represent considerable resistance to the adjustment of redox conditions even at uncontaminated sites. Hydrogen peroxide reduction by aquifer solid samples proceeds rapidly relative to microbially mediated decomposition. The study indicates the need for closer scrutiny of the predictability and cost effectiveness of attempts to manipulate redox conditions in poorly poised aquifer systems.

  8. Energy Savings from Industrial Water Reductions

    SciTech Connect

    Rao, Prakash; McKane, Aimee; de Fontaine, Andre

    2015-08-03

    Although it is widely recognized that reducing freshwater consumption is of critical importance, generating interest in industrial water reduction programs can be hindered for a variety of reasons. These include the low cost of water, greater focus on water use in other sectors such as the agriculture and residential sectors, high levels of unbilled and/or unregulated self-supplied water use in industry, and lack of water metering and tracking capabilities at industrial facilities. However, there are many additional components to the resource savings associated with reducing site water use beyond the water savings alone, such as reductions in energy consumption, greenhouse gas emissions, treatment chemicals, and impact on the local watershed. Understanding and quantifying these additional resource savings can expand the community of businesses, NGOs, government agencies, and researchers with a vested interest in water reduction. This paper will develop a methodology for evaluating the embedded energy consumption associated with water use at an industrial facility. The methodology developed will use available data and references to evaluate the energy consumption associated with water supply and wastewater treatment outside of a facility’s fence line for various water sources. It will also include a framework for evaluating the energy consumption associated with water use within a facility’s fence line. The methodology will develop a more complete picture of the total resource savings associated with water reduction efforts and allow industrial water reduction programs to assess the energy and CO2 savings associated with their efforts.

  9. Reduction/Transformation Operators

    2006-09-01

    RTOp (reduction/transformation operators) is a collection of C++ software that provides the basic mechanism for implementinig vector operations in a flexible and efficient manner. This is the main interface utilized by Thyra to allow for the specification of specific vector reduction and/or transformation operations. The RTOp package contains three different types of software. (a) a small number of interoperability interfaces. (b) support software including code for the parallel SPMD mode based on only Teuchos::Comm(and notmore » MPl directly(, and (c) a library of pre-implemented RTOp subclasses for everything from simple AXPYs and norms, to more specialized vector operations. RTOp allows an algorithm developer to implement their own RTOp subclasses in a way that is independent from any specific serial, parallel, out-of-core or other type of vector implementation. RTOp is a required package by Thyra and MOOCHO. (c)« less

  10. Tensor sufficient dimension reduction

    PubMed Central

    Zhong, Wenxuan; Xing, Xin; Suslick, Kenneth

    2015-01-01

    Tensor is a multiway array. With the rapid development of science and technology in the past decades, large amount of tensor observations are routinely collected, processed, and stored in many scientific researches and commercial activities nowadays. The colorimetric sensor array (CSA) data is such an example. Driven by the need to address data analysis challenges that arise in CSA data, we propose a tensor dimension reduction model, a model assuming the nonlinear dependence between a response and a projection of all the tensor predictors. The tensor dimension reduction models are estimated in a sequential iterative fashion. The proposed method is applied to a CSA data collected for 150 pathogenic bacteria coming from 10 bacterial species and 14 bacteria from one control species. Empirical performance demonstrates that our proposed method can greatly improve the sensitivity and specificity of the CSA technique. PMID:26594304

  11. Injury reduction at Fermilab

    SciTech Connect

    Griffing, Bill; /Fermilab

    2005-06-01

    In a recent DOE Program Review, Fermilab's director presented results of the laboratory's effort to reduce the injury rate over the last decade. The results, shown in the figure below, reveal a consistent and dramatic downward trend in OSHA recordable injuries at Fermilab. The High Energy Physics Program Office has asked Fermilab to report in detail on how the laboratory has achieved the reduction. In fact, the reduction in the injury rate reflects a change in safety culture at Fermilab, which has evolved slowly over this period, due to a series of events, both planned and unplanned. This paper attempts to describe those significant events and analyze how each of them has shaped the safety culture that, in turn, has reduced the rate of injury at Fermilab to its current value.

  12. Chemical Looping Combustion Kinetics

    SciTech Connect

    Edward Eyring; Gabor Konya

    2009-03-31

    One of the most promising methods of capturing CO{sub 2} emitted by coal-fired power plants for subsequent sequestration is chemical looping combustion (CLC). A powdered metal oxide such as NiO transfers oxygen directly to a fuel in a fuel reactor at high temperatures with no air present. Heat, water, and CO{sub 2} are released, and after H{sub 2}O condensation the CO{sub 2} (undiluted by N{sub 2}) is ready for sequestration, whereas the nickel metal is ready for reoxidation in the air reactor. In principle, these processes can be repeated endlessly with the original nickel metal/nickel oxide participating in a loop that admits fuel and rejects ash, heat, and water. Our project accumulated kinetic rate data at high temperatures and elevated pressures for the metal oxide reduction step and for the metal reoxidation step. These data will be used in computational modeling of CLC on the laboratory scale and presumably later on the plant scale. The oxygen carrier on which the research at Utah is focused is CuO/Cu{sub 2}O rather than nickel oxide because the copper system lends itself to use with solid fuels in an alternative to CLC called 'chemical looping with oxygen uncoupling' (CLOU).

  13. Reduction of astrographic catalogues

    NASA Technical Reports Server (NTRS)

    Stock, J.; Prugna, F. D.; Cova, J.

    1984-01-01

    An automatic program for the reduction of overlapping Carte du Ciel plates is described. The projection and transformation equations are given and the RAA subprogram flow is outlined. The program was applied to two different sets of data, namely to nine overlapping plates of the Cape Zone of the CdC, and to fifteen plates taken with the CIDA-refractor of the open cluster Tr10.

  14. Aluminum reduction cell electrode

    DOEpatents

    Goodnow, Warren H.; Payne, John R.

    1982-01-01

    The invention is directed to cathode modules comprised of refractory hard metal materials, such as TiB.sub.2, for an electrolytic cell for the reduction of alumina wherein the modules may be installed and replaced during operation of the cell and wherein the structure of the cathode modules is such that the refractory hard metal materials are not subjected to externally applied forces or rigid constraints.

  15. Emissions reductions strategies

    SciTech Connect

    Sirois, R.H.

    1996-12-31

    This paper consists of the series of viewgraphs used by the author during his presentation. They tabulate nitrogen oxide reduction techniques, technical evaluation of NOx control techniques, critical system design parameters for SNCR processes, major concerns for SCR retrofit applications, integrating technologies, sulfur dioxide control for a coal fired power plant, heavy metals on US EPA`s HAPs list, and mercury emissions. Other slides show flow charts of some of these processes, as well as diagrams of equipment.

  16. [Aware and cooperative reduction].

    PubMed

    Tambone, V; Ghilardi, G

    2012-01-01

    The aim of this work is to address the question of reduction in the scientific method, to evaluate its legitimacy as well as its pro and contra from an epistemological point of view. In the first paragraph we classify some kinds of reductionism, analysing their presuppositions and epistemological status and showing some examples of scientific reduction. The presentation includes a classificatory table that shows some of the different forms of biological reductionism. In the second paragraph we study the epistemology of science starting from its modern beginning: the Vienna Circle, focusing on the meaning of methodological reductionism. What did it mean for science to define itself mainly as method, which effects did this new concept of science have on methodology and what kind of problems did this movement bring about. In the third paragraph we examine the reactions triggered by methodological reductionism, we analyze the theoretical consistency of these answers, trying to offer a balanced view. We show how complexity can be seen as a paradigm of the anti-reductionism effort, and we study its epistemological basis. In the fourth paragraph we outline our operative proposal: the reduction that is both aware and cooperative. We point out the main reasons why science cannot avoid being reductive in some way, and therefore how we need to deal with this feature in order to prevent it to degenerate into reductionism. We show some examples of this new proposal taken from the practical realm and from literature, where it is possible to discern the spirit of this alternative methodology. PMID:22964706

  17. Aluminum reduction cell electrode

    DOEpatents

    Goodnow, W.H.; Payne, J.R.

    1982-09-14

    The invention is directed to cathode modules comprised of refractory hard metal materials, such as TiB[sub 2], for an electrolytic cell for the reduction of alumina wherein the modules may be installed and replaced during operation of the cell and wherein the structure of the cathode modules is such that the refractory hard metal materials are not subjected to externally applied forces or rigid constraints. 9 figs.

  18. Television noise reduction device

    NASA Technical Reports Server (NTRS)

    Gordon, B. L.; Stamps, J. C. (Inventor)

    1975-01-01

    A noise reduction system that divides the color video signal into its luminance and chrominance components is reported. The luminance component of a given frame is summed with the luminance component of at least one preceding frame which was stored on a disc recorder. The summation is carried out so as to achieve a signal amplitude equivalent to that of the original signal. The averaged luminance signal is then recombined with the chrominance signal to achieve a noise-reduced television signal.

  19. Somatic reduction in cycads.

    PubMed

    Storey, W B

    1968-02-01

    Recurrent somatic reduction is a normal ontogenetic process in apogeotropic roots of cycads, which develop into dichotomously branching coralloid masses. The reduced cells make up part of a ring of differentiated cortical tissue lying midway between the pericycle and the epidermis; they serve as fillers among the large cells and become charged with slime. The differentiated tissue is colonized by a species of blue-green algae.

  20. Thermochemical nitrate reduction

    SciTech Connect

    Cox, J.L.; Lilga, M.A.; Hallen, R.T.

    1992-09-01

    A series of preliminary experiments was conducted directed at thermochemically converting nitrate to nitrogen and water. Nitrates are a major constituent of the waste stored in the underground tanks on the Hanford Site, and the characteristics and effects of nitrate compounds on stabilization techniques must be considered before permanent disposal operations begin. For the thermochemical reduction experiments, six reducing agents (ammonia, formate, urea, glucose, methane, and hydrogen) were mixed separately with {approximately}3 wt% NO{sub 3}{sup {minus}} solutions in a buffered aqueous solution at high pH (13); ammonia and formate were also mixed at low pH (4). Reactions were conducted in an aqueous solution in a batch reactor at temperatures of 200{degrees}C to 350{degrees}C and pressures of 600 to 2800 psig. Both gas and liquid samples were analyzed. The specific components analyzed were nitrate, nitrite, nitrous oxide, nitrogen, and ammonia. Results of experimental runs showed the following order of nitrate reduction of the six reducing agents in basic solution: formate > glucose > urea > hydrogen > ammonia {approx} methane. Airnmonia was more effective under acidic conditions than basic conditions. Formate was also effective under acidic conditions. A more thorough, fundamental study appears warranted to provide additional data on the mechanism of nitrate reduction. Furthermore, an expanded data base and engineering feasibility study could be used to evaluate conversion conditions for promising reducing agents in more detail and identify new reducing agents with improved performance characteristics.

  1. Uranium Reduction by Clostridia

    SciTech Connect

    Francis, A.J.; Dodge, Cleveland J.; Gillow, Jeffrey B.

    2006-04-05

    The FRC groundwater and sediment contain significant concentrations of U and Tc and are dominated by low pH, and high nitrate and Al concentrations where dissimilatory metal reducing bacterial activity may be limited. The presence of Clostridia in Area 3 at the FRC site has been confirmed and their ability to reduce uranium under site conditions will be determined. Although the phenomenon of uranium reduction by Clostridia has been firmly established, the molecular mechanisms underlying such a reaction are not very clear. The authors are exploring the hypothesis that U(VI) reduction occurs through hydrogenases and other enzymes (Matin and Francis). Fundamental knowledge of metal reduction using Clostridia will allow us to exploit naturally occurring processes to attenuate radionuclide and metal contaminants in situ in the subsurface. The outline for this report are as follows: (1) Growth of Clostridium sp. under normal culture conditions; (2) Fate of metals and radionuclides in the presence of Clostridia; (3) Bioreduction of uranium associated with nitrate, citrate, and lepidocrocite; and (4) Utilization of Clostridium sp. for immobilization of uranium at the FRC Area 3 site.

  2. Chemical information science coverage in Chemical Abstracts.

    PubMed

    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.

  3. Diversity of Contaminant Reduction Reactions by Zero-Valent Iron: Role of the Reductate

    SciTech Connect

    Miehr, R; Tratnyek, Paul G.; Bandstra, J; Scherer, Michelle; Alowitz, M; Bylaska, Eric J.

    2004-01-01

    The reactions of 8 model contaminants with 9 types of granular Fe(0) were studied in batch experiments using consistent experimental conditions. The model contaminants (herein referred to as reductates because they were reduced by the iron metal) included cations (Cu2+), anions (CrO42-; NO3-; and 5,5,7,7-indigotetrasulfonate), and neutral species (2-chloroacetophenone; 2,4,6-trinitrotoluene; carbon tetrachloride; and trichloroethene). The diversity of this range of reductates offers a uniquely broad perspective on the reactivity of Fe(0). Rate constants for disappearance of the reductates vary over as much as 4 orders of magnitude for particular reductates (due to differences in the 9 types of iron) but differences among the reductates were even larger, ranging over almost 7 orders of magnitude. Various ways of summarizing the data all suggest that relative reactivities with Fe(0) varies in the order: Cu2, I4S > 2CAP, TNT > CT, Cr6 > TCE > NO3. Although the reductate h as the largest effect on disappearance kinetics, more subtle differences in reactivity due to the type of Fe(0) suggests that removal of Cr6 and NO3 (the inorganic anions) involves adsorption to oxides on the Fe(0), whereas the disappearance kinetics of all other types of reductants is favored by reduction on comparatively oxide-free metal. Correlation analysis of the disappearance rate constants using descriptors of the reductates calculated by molecular modeling (energies of the lowest unoccupied molecular orbitals, LUMO, highest occupied molecular orbitals, HOMO, and HOMO-LUMO gaps) showed that reactivities generally increase with decreasing ELUMO and increasing EGAP (and, therefore, increasing chemical hardness h).

  4. Chromium isotopes as indicators of hexavalent chromium reduction

    SciTech Connect

    Johnson, Thomas M.

    2012-03-20

    This is the final report for a university research project which advanced development of a new technology for identifying chemical reduction of hexavalent chromium contamination in groundwater systems. Reduction renders mobile and toxic hexavalent chromium immobile and less toxic. The new method uses stable isotope ratio measurements, which are made using multicollector ICP-mass spectrometry. The main objectives of this project were completed during the project period and two peer-reviewed articles were published to disseminate the information gained.

  5. Forecasting for energy and chemical decision analysis

    SciTech Connect

    Cazalet, E.G.

    1984-08-01

    This paper focuses on uncertainty and bias in forecasts used for major energy and chemical investment decisions. Probability methods for characterizing uncertainty in the forecast are reviewed. Sources of forecasting bias are classified based on the results of relevant psychology research. Examples are drawn from the energy and chemical industry to illustrate the value of explicit characterization of uncertainty and reduction of bias in forecasts.

  6. Reduction of turbomachinery noise

    NASA Technical Reports Server (NTRS)

    Waitz, Ian A. (Inventor); Brookfield, John M. (Inventor); Sell, Julian (Inventor); Hayden, Belva J. (Inventor); Ingard, K. Uno (Inventor)

    1999-01-01

    In the invention, propagating broad band and tonal acoustic components of noise characteristic of interaction of a turbomachine blade wake, produced by a turbomachine blade as the blade rotates, with a turbomachine component downstream of the rotating blade, are reduced. This is accomplished by injection of fluid into the blade wake through a port in the rotor blade. The mass flow rate of the fluid injected into the blade wake is selected to reduce the momentum deficit of the wake to correspondingly increase the time-mean velocity of the wake and decrease the turbulent velocity fluctuations of the wake. With this fluid injection, reduction of both propagating broad band and tonal acoustic components of noise produced by interaction of the blade wake with a turbomachine component downstream of the rotating blade is achieved. In a further noise reduction technique, boundary layer fluid is suctioned into the turbomachine blade through a suction port on the side of the blade that is characterized as the relatively low-pressure blade side. As with the fluid injection technique, the mass flow rate of the fluid suctioned into the blade is here selected to reduce the momentum deficit of the wake to correspondingly increase the time-mean velocity of the wake and decrease the turbulent velocity fluctuations of the wake; reduction of both propagating broad band and tonal acoustic components of noise produced by interaction of the blade wake with a turbomachine component downstream of the rotating blade is achieved with this suction technique. Blowing and suction techniques are also provided in the invention for reducing noise associated with the wake produced by fluid flow around a stationary blade upstream of a rotating turbomachine.

  7. Electrolytic oxide reduction system

    DOEpatents

    Wiedmeyer, Stanley G; Barnes, Laurel A; Williamson, Mark A; Willit, James L; Berger, John F

    2015-04-28

    An electrolytic oxide reduction system according to a non-limiting embodiment of the present invention may include a plurality of anode assemblies, a plurality of cathode assemblies, and a lift system configured to engage the anode and cathode assemblies. The cathode assemblies may be alternately arranged with the anode assemblies such that each cathode assembly is flanked by two anode assemblies. The lift system may be configured to selectively engage the anode and cathode assemblies so as to allow the simultaneous lifting of any combination of the anode and cathode assemblies (whether adjacent or non-adjacent).

  8. Reductive Desulfurization of Dibenzyldisulfide

    PubMed Central

    Miller, Kathleen W.

    1992-01-01

    Dibenzyldisulfide was reductively degraded by a methanogenic mixed culture derived from a sewage digestor. Toluene was produced with benzyl mercaptan as an intermediate in sulfur-limited medium. Toluene production was strictly associated with biological activity; however, the reducing agent for the culture medium, Ti(III), was partially responsible for production of benzyl mercaptan. Sulfide was not detected. Additions of sodium sulfide did not inhibit toluene production. Additions of 2-bromoethane sulfonic acid prevented methanogenesis but did not adversely affect toluene yields. PMID:16348733

  9. NSF grant reductions

    NASA Astrophysics Data System (ADS)

    Jones, R.

    Many National Science Foundation grants will be reduced this year as a result of a provision in H.R. 3299. The provision stems from disagreement between the Congress and the administration on how to make budget deficit cuts required by the Gramm-Rudman-Hollings budget law. An agreement was made to cut $4.55 billion through a reduction in discretionary spending, by what amounts to 1.4% across-the-board. The cuts will affect all discretionary federal domestic and defense programs.

  10. Aluminum reduction cell electrode

    DOEpatents

    Payne, John R.

    1983-09-20

    The invention is directed to an anode-cathode structure for an electrolytic cell for the reduction of alumina wherein the structure is comprised of a carbon anode assembly which straddles a wedge-shaped refractory hard metal cathode assembly having steeply sloped cathodic surfaces, each cathodic surface being paired in essentially parallel planar relationship with an anode surface. The anode-cathode structure not only takes into account the structural weakness of refractory hard metal materials but also permits the changing of the RHM assembly during operation of the cell. Further, the anode-cathode structure enhances the removal of anode gas from the interpolar gap between the anode and cathode surfaces.

  11. Perchlorate reduction by microbes inhabiting oil reservoirs

    NASA Astrophysics Data System (ADS)

    Liebensteiner, Martin; Stams, Alfons; Lomans, Bart

    2014-05-01

    Microbial perchlorate and chlorate reduction is a unique type of anaerobic respiration as during reduction of (per)chlorate chlorite is formed, which is then split into chloride and molecular oxygen. In recent years it was demonstrated that (per)chlorate-reducing bacteria may employ oxygenase-dependent pathways for the degradation of aromatic and aliphatic hydrocarbons. These findings suggested that (per)chlorate may be used as oxygen-releasing compound in anoxic environments that contain hydrocarbons, such as polluted soil sites and oil reservoirs. We started to study perchlorate reduction by microbes possibly inhabiting oil reservoirs. One of the organisms studied was Archaeoglobus fulgidus. This extremely thermophilic archaeon is known as a major contributor to souring in hot oil reservoirs. A. fulgidus turned out to be able to use perchlorate as terminal electron acceptor for growth with lactate (Liebensteiner et al 2013). Genome based physiological experiments indicated that A. fulgidus possesses a novel perchlorate reduction pathway. Perchlorate is first reduced to chlorite, but chlorite is not split into chloride and molecular oxygen as occurs in bacteria. Rather, chlorite reacts chemically with sulfide, forming oxidized sulfur compounds, which are reduced to sulfide in the electron transport chain by the archaeon. The dependence of perchlorate reduction on sulfur compounds could be shown. The implications of our findings as novel strategy for microbiological enhanced oil recovery and for souring mitigation are discussed. Liebensteiner MG, Pinkse MWH, Schaap PJ, Stams AJM and Lomans BP (2013) Archaeal (per)chlorate reduction at high temperature, a matter of abiotic-biotic reactions. Science 340: 85-87

  12. Reduction operators of Burgers equation

    PubMed Central

    Pocheketa, Oleksandr A.; Popovych, Roman O.

    2013-01-01

    The solution of the problem on reduction operators and nonclassical reductions of the Burgers equation is systematically treated and completed. A new proof of the theorem on the special “no-go” case of regular reduction operators is presented, and the representation of the coefficients of operators in terms of solutions of the initial equation is constructed for this case. All possible nonclassical reductions of the Burgers equation to single ordinary differential equations are exhaustively described. Any Lie reduction of the Burgers equation proves to be equivalent via the Hopf–Cole transformation to a parameterized family of Lie reductions of the linear heat equation. PMID:23576819

  13. Cooperative Threat Reduction: Cooperation Threat Reduction Program Liquid Propellant Disposition Project

    NASA Astrophysics Data System (ADS)

    2002-09-01

    This audit is one in a series of audits the Deputy Secretary of Defense requested. As part of the Cooperative Threat Reduction (CTR) Program, DoD agreed to assist the Russian Federation in disposing of its liquid rocket propellant. Public Law 102-228 (section 2551 NOTE, title 22, United States Code), the Soviet Nuclear Threat Reduction Act of 1991 designates DoD as the executive agent for the CTR Program. Specific objectives of the act are to destroy chemical, nuclear, and other weapons; transport, store, disable, and safeguard weapons in connection with their destruction; and establish verifiable safeguards against proliferation of weapons of mass destruction. The Office of the Assistant Secretary of Defense (International Security Policy), under the Office of the Under Secretary of Defense for Policy, develops, coordinates, and oversees implementation of policy for the CTR Program. The CTR Directorate, Defense Threat Reduction Agency operates the program.

  14. Chemical Sensing for Buried Landmines - Fundamental Processes Influencing Trace Chemical Detection

    SciTech Connect

    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. Cyclone reduction of taconite. Final report

    SciTech Connect

    Taylor, P.R.; Bartlett, R.W.; Abdel-latif, M.A.; Hou, X.; Kumar, P.

    1995-05-01

    A cyclone reactor system for the partial reduction and melting of taconite concentrate fines has been engineered, designed and operated. A non-transferred arc plasma torch was employed as a heat source. Taconite fines, carbon monoxide, and carbon dioxide were fed axially into the reactor, while the plasma gas was introduced tangentially into the cyclone. The average reactor temperature was maintained at above 1400{degrees}C, and reduction experiments were performed under various conditions. The influence of the following parameters on the reduction of taconite was investigated experimentally; carbon monoxide to carbon dioxide inlet feed ratio, carbon monoxide inlet partial pressure, and average reactor temperature. The interactions of the graphite lining with carbon dioxide and taconite were also studied. An attempt was made to characterize the flow behavior of the molten product within the cyclone. The results suggest that the system may approach a plug flow reactor, with little back mixing. Finally, a fundamental mathematical model was developed. The model describes the flow dynamics of gases and solid particles in a cyclone reactor, energy exchange, mass transfer, and the chemical kinetics associated with cyclone smelting of taconite concentrate fines. The influence of the various parameters on the reduction and melting of taconite particles was evaluated theoretically.

  16. Dimension reduction and source identification for multispecies groundwater contamination.

    PubMed

    Duffy, C J; Brandes, D

    2001-03-01

    Assessment of chemical contamination at large industrial complexes with long and sometimes unknown histories of operation represents a challenging environmental problem. The spatial and temporal complexity of the contaminant may be due to changes in production processes, differences in the chemical transport, and the physical heterogeneity of the soil and aquifer materials. Traditional mapping techniques are of limited value for sites where dozens of chemicals with diverse transport characteristics may be scattered over large spatial areas without documentation of disposal histories. In this context, a site with a long and largely undocumented disposal history of shallow groundwater contamination is examined using principal component analysis (PCA). The dominant chemical groups and chemical "modes" at the site were identified. PCA results indicate that five primary and three transition chemical groups can be identified in the space of the first three eigenvectors of the correlation matrix, which account for 61% of the total variance of the data. These groups represent a significant reduction in the dimension of the original data (116 chemicals). It is shown that each group represents a class of chemicals with similar chemo-dynamic properties and/or environmental response. Finally, the groups are mapped back onto the site map to infer delineation of contaminant source areas for each class of compounds. The approach serves as a preliminary step in subsurface characterization, and a data reduction strategy for source identification, subsurface modeling and remediation planning.

  17. Islam and harm reduction.

    PubMed

    Kamarulzaman, A; Saifuddeen, S M

    2010-03-01

    Although drugs are haram and therefore prohibited in Islam, illicit drug use is widespread in many Islamic countries throughout the world. In the last several years increased prevalence of this problem has been observed in many of these countries which has in turn led to increasing injecting drug use driven HIV/AIDS epidemic across the Islamic world. Whilst some countries have recently responded to the threat through the implementation of harm reduction programmes, many others have been slow to respond. In Islam, The Quran and the Prophetic traditions or the Sunnah are the central sources of references for the laws and principles that guide the Muslims' way of life and by which policies and guidelines for responses including that of contemporary social and health problems can be derived. The preservation and protection of the dignity of man, and steering mankind away from harm and destruction are central to the teachings of Islam. When viewed through the Islamic principles of the preservation and protection of the faith, life, intellect, progeny and wealth, harm reduction programmes are permissible and in fact provide a practical solution to a problem that could result in far greater damage to the society at large if left unaddressed.

  18. Microbial reduction of iodate

    USGS Publications Warehouse

    Councell, T.B.; Landa, E.R.; Lovley, D.R.

    1997-01-01

    The different oxidation species of iodine have markedly different sorption properties. Hence, changes in iodine redox states can greatly affect the mobility of iodine in the environment. Although a major microbial role has been suggested in the past to account for these redox changes, little has been done to elucidate the responsible microorganisms or the mechanisms involved. In the work presented here, direct microbial reduction of iodate was demonstrated with anaerobic cell suspensions of the sulfate reducing bacterium Desulfovibrio desulfuricans which reduced 96% of an initial 100 ??M iodate to iodide at pH 7 in 30 mM NaHCO3 buffer, whereas anaerobic cell suspensions of the dissimilatory Fe(III)-reducing bacterium Shewanella putrefaciens were unable to reduce iodate in 30 mM NaHCO3 buffer (pH 7). Both D. desulfuricans and S. putrefaciens were able to reduce iodate at pH 7 in 10 mM HEPES buffer. Both soluble ferrous iron and sulfide, as well as iron monosulfide (FeS) were shown to abiologically reduce iodate to iodide. These results indicate that ferric iron and/or sulfate reducing bacteria are capable of mediating both direct, enzymatic, as well as abiotic reduction of iodate in natural anaerobic environments. These microbially mediated reactions may be important factors in the fate and transport of 129I in natural systems.

  19. Harm Reduction From Below

    PubMed Central

    Van Schipstal, Inge; Berning, Moritz; Murray, Hayley

    2016-01-01

    This article focuses on how recreational drug users in the Netherlands and in online communities navigate the risks and reduce the harms they associate with psychoactive drug use. To do so, we examined the protective practices they invent, use, and share with their immediate peers and with larger drug experimenting communities online. The labor involved in protective practices and that which ultimately informs harm reduction from below follows three interrelated trajectories: (1) the handling and sharing of drugs to facilitate hassle-free drug use, (2) creating pleasant and friendly spaces that we highlight under the practices of drug use attunements, and (3) the seeking and sharing of information in practices to spread the good high. We focus not only on users’ concerns but also on how these concerns shape their approach to drugs, what young people do to navigate uncertainties, and how they reach out to and create different sources of knowledge to minimize adversities and to improve highs. Harm reduction from below, we argue, can best be seen in the practices of sharing around drug use and in the caring for the larger community of drug-using peers. PMID:27721525

  20. Core Noise Reduction

    NASA Technical Reports Server (NTRS)

    Hultgren, Lennart S.

    2011-01-01

    This presentation is a technical summary of and outlook for NASA-internal and NASA-sponsored external research on core (combustor and turbine) noise funded by the Fundamental Aeronautics Program Subsonic Fixed Wing (SFW) Project. Sections of the presentation cover: the SFW system-level noise metrics for the 2015, 2020, and 2025 timeframes; turbofan design trends and their aeroacoustic implications; the emerging importance of core noise and its relevance to the SFW Reduce-Perceived-Noise Technical Challenge; and the current research activities in the core noise area. Recent work1 on the turbine-transmission loss of combustor noise is briefly described, two2,3 new NRA efforts in the core-noise area are outlined, and an effort to develop CMC-based acoustic liners for broadband noise reduction suitable for turbofan-core application is delineated. The NASA Fundamental Aeronautics Program has the principal objective of overcoming today's national challenges in air transportation. The reduction of aircraft noise is critical to enabling the anticipated large increase in future air traffic. The Subsonic Fixed Wing Project's Reduce-Perceived-Noise Technical Challenge aims to develop concepts and technologies to dramatically reduce the perceived aircraft noise outside of airport boundaries.

  1. Process simulation of aluminum reduction cells

    SciTech Connect

    Tabsh, I.; Dupuis, M.; Gomes, A.

    1996-10-01

    A program was developed to model the dynamic behavior of an aluminum reduction cell. The program simulates the physical process by solving the heat and mass balance equations that characterize the behavior of eleven chemical species in the system. It also models operational events (such as metal tapping, anode change, etc.) and the process control logic including various alumina feeding policies and anode effect quenching. The program is a PC based Windows{reg_sign} application that takes full advantage of the Windows user interface. This paper describes the implementation of the process model and the control logic. Various results using the simulation are compared to measured data.

  2. Adaptive deployment of model reductions for tau-leaping simulation

    NASA Astrophysics Data System (ADS)

    Wu, Sheng; Fu, Jin; Petzold, Linda R.

    2015-05-01

    Multiple time scales in cellular chemical reaction systems often render the tau-leaping algorithm inefficient. Various model reductions have been proposed to accelerate tau-leaping simulations. However, these are often identified and deployed manually, requiring expert knowledge. This is time-consuming and prone to error. In previous work, we proposed a methodology for automatic identification and validation of model reduction opportunities for tau-leaping simulation. Here, we show how the model reductions can be automatically and adaptively deployed during the time course of a simulation. For multiscale systems, this can result in substantial speedups.

  3. Adaptive deployment of model reductions for tau-leaping simulation

    PubMed Central

    Fu, Jin; Petzold, Linda R.

    2015-01-01

    Multiple time scales in cellular chemical reaction systems often render the tau-leaping algorithm inefficient. Various model reductions have been proposed to accelerate tau-leaping simulations. However, these are often identified and deployed manually, requiring expert knowledge. This is time-consuming and prone to error. In previous work, we proposed a methodology for automatic identification and validation of model reduction opportunities for tau-leaping simulation. Here, we show how the model reductions can be automatically and adaptively deployed during the time course of a simulation. For multiscale systems, this can result in substantial speedups. PMID:26026435

  4. Adaptive deployment of model reductions for tau-leaping simulation.

    PubMed

    Wu, Sheng; Fu, Jin; Petzold, Linda R

    2015-05-28

    Multiple time scales in cellular chemical reaction systems often render the tau-leaping algorithm inefficient. Various model reductions have been proposed to accelerate tau-leaping simulations. However, these are often identified and deployed manually, requiring expert knowledge. This is time-consuming and prone to error. In previous work, we proposed a methodology for automatic identification and validation of model reduction opportunities for tau-leaping simulation. Here, we show how the model reductions can be automatically and adaptively deployed during the time course of a simulation. For multiscale systems, this can result in substantial speedups.

  5. Chemical Ecology: Chemical Communication in Nature.

    ERIC Educational Resources Information Center

    Wood, William F.

    1983-01-01

    Substances that deliver chemical messages between same/different species are called semiochemicals. Surveyed are three types of semiochemicals (pheromones, allomones, and kairomones), types of organisms involved, and specific chemicals used to carry the various kinds of messages. (JN)

  6. Reductant injection and mixing system

    DOEpatents

    Reeves, Matt; Henry, Cary A.; Ruth, Michael J.

    2016-02-16

    A gaseous reductant injection and mixing system is described herein. The system includes an injector for injecting a gaseous reductant into an exhaust gas stream, and a mixer attached to a surface of the injector. The injector includes a plurality of apertures through which the gaseous reductant is injected into an exhaust gas stream. The mixer includes a plurality of fluid deflecting elements.

  7. Active noise reduction

    NASA Astrophysics Data System (ADS)

    Geyer, Carolyn R.

    Active noise reduction (ANR) techniques are described with reference to their application to crewmembers during aircraft operation to enhance productivity and safety. ANR concepts and theory are explained, and the development of protective ANR systems for direct implementation are described. Sound attenuation testing was conducted to study the feasibility of aircraft-powered ANR systems, and the positive results spurred their development for compatibility with flight helmets. The Helmets Limited ANR system uses a bypass mode at times of limited available power and complements the use of passive sound attenuation. Subjective testing results show that the device is effective, and a planned program of intensive evaluation is discussed. The aircraft that require an ANR system are listed, and key areas of implementation include battery power and the combination of ANR circuitry and helmet oxygen masks. It is suggested that ANR techniques can positively impact the efficiency and performance of crewmembers in high-noise-level aircraft.

  8. Hazardous solvent source reduction

    SciTech Connect

    Callahan, M.S.; Green, B.

    1995-09-01

    This book is written for the managers, production leaders, and operations staff tasked with the job of eliminating hazardous cleaning solvents from their workplace. Information regarding the location, evaluation, and implementation of environmentally preferred cleaning technologies is offered for a broad range of applications. These include: removal of grease and grime from a piece of equipment during maintenance, cleaning small parts before assembly, defluxing printed circuit boards and assemblies, and stripping paint from field vehicles and aircraft. Moving beyond the limits of source reduction alone, this book provides complete information on the planning, staffing, and execution of a pollution prevention program, alternative and in-use cleaner testing, waste recycling and treatment, air emission control, replacement system design, and system economics. For the environmental specialist, this book helps to bridge the gap between regulatory requirements and shop-floor constraints.

  9. Aircraft engine pollution reduction.

    NASA Technical Reports Server (NTRS)

    Rudey, R. A.

    1972-01-01

    The effect of engine operation on the types and levels of the major aircraft engine pollutants is described and the major factors governing the formation of these pollutants during the burning of hydrocarbon fuel are discussed. Methods which are being explored to reduce these pollutants are discussed and their application to several experimental research programs are pointed out. Results showing significant reductions in the levels of carbon monoxide, unburned hydrocarbons, and oxides of nitrogen obtained from experimental combustion research programs are presented and discussed to point out potential application to aircraft engines. An experimental program designed to develop and demonstrate these and other advanced, low pollution combustor design methods is described. Results that have been obtained to date indicate considerable promise for reducing advanced engine exhaust pollutants to levels significantly below current engines.

  10. Aluminum reduction cell electrode

    DOEpatents

    Payne, J.R.

    1983-09-20

    The invention is directed to an anode-cathode structure for an electrolytic cell for the reduction of alumina wherein the structure is comprised of a carbon anode assembly which straddles a wedge-shaped refractory hard metal cathode assembly having steeply sloped cathodic surfaces, each cathodic surface being paired in essentially parallel planar relationship with an anode surface. The anode-cathode structure not only takes into account the structural weakness of refractory hard metal materials but also permits the changing of the RHM assembly during operation of the cell. Further, the anode-cathode structure enhances the removal of anode gas from the interpolar gap between the anode and cathode surfaces. 10 figs.

  11. The Chemical Engineer in the Chemical Industry.

    ERIC Educational Resources Information Center

    Zabicky, Jacob

    1986-01-01

    Describes a course for third- or fourth-year chemical engineering students designed to acquaint them with the chemical industry. The course deals with productivity, characteristics of the chemical industry, sources of information, industrial intelligence, research and development, patent law, technology transfer, and quality control. (TW)

  12. Dose Reduction Techniques

    SciTech Connect

    WAGGONER, L.O.

    2000-05-16

    As radiation safety specialists, one of the things we are required to do is evaluate tools, equipment, materials and work practices and decide whether the use of these products or work practices will reduce radiation dose or risk to the environment. There is a tendency for many workers that work with radioactive material to accomplish radiological work the same way they have always done it rather than look for new technology or change their work practices. New technology is being developed all the time that can make radiological work easier and result in less radiation dose to the worker or reduce the possibility that contamination will be spread to the environment. As we discuss the various tools and techniques that reduce radiation dose, keep in mind that the radiological controls should be reasonable. We can not always get the dose to zero, so we must try to accomplish the work efficiently and cost-effectively. There are times we may have to accept there is only so much you can do. The goal is to do the smart things that protect the worker but do not hinder him while the task is being accomplished. In addition, we should not demand that large amounts of money be spent for equipment that has marginal value in order to save a few millirem. We have broken the handout into sections that should simplify the presentation. Time, distance, shielding, and source reduction are methods used to reduce dose and are covered in Part I on work execution. We then look at operational considerations, radiological design parameters, and discuss the characteristics of personnel who deal with ALARA. This handout should give you an overview of what it takes to have an effective dose reduction program.

  13. Effect of nitrate on microbial perchlorate reduction

    NASA Astrophysics Data System (ADS)

    Sun, Y.; Coates, J. D.

    2007-12-01

    Over the last decade perchlorate has been recognized as an important emerging water contaminant that poses a significant public health threat. Because of its chemical stability, low ionic charge density, and significant water solubility microbial remediation has been identified as the most feasible method for its in situ attenuation. Our previous studies have demonstrated that dissimilatory perchlorate reducing bacteria (DPRB) capable of the respiratory reduction of perchlorate into innocuous chloride are ubiquitous in soil and sedimentary environments. As part of their metabolism these organisms reduce perchlorate to chlorite which is subsequently dismutated into chloride and molecular oxygen. These initial steps are mediated by the perchlorate reductase and chlorite dismutase enzymes respectively. Previously we found that the activity of these organisms is dependent on the presence of molybdenum and is inhibited by the presence of oxygen and to different extents nitrate. However, to date, there is little understanding of the mechanisms involved in the regulation of perchlorate reduction by oxygen and nitrate. As a continuation of our studies into the factors that control DPRB activity we investigated these regulatory mechanisms in more detail as a model organism, Dechloromonas aromatica strain RCB, transitions from aerobic metabolism through nitrate reduction to perchlorate reduction. In series of growth transition studies where both nitrate and perchlorate were present, preference for nitrate to perchlorate was observed regardless of the nitrate to perchlorate ratio. Even when the organism was pre-grown anaerobically in perchlorate, nitrate was reduced prior to perchlorate. Using non-growth washed cell suspension, perchlorate- grown D. aromatica was capable of reducing both perchlorate and nitrate concomitantly suggesting the preferentially utilization of nitrate was not a result of enzyme functionality. To elucidate the mechanism for preferential utilization of

  14. Characterization study of polycrystalline tin oxide surfaces before and after reduction in CO

    NASA Technical Reports Server (NTRS)

    Drawdy, Jean E.; Hoflund, Gar B.; Davidson, Mark R.; Schryer, David R.

    1990-01-01

    Polycrystalline tin oxide surfaces have been examined before and after reduction in 40 Torr of CO at 100 and 175 C using Auger electron spectroscopy (AES), electron spectroscopy for chemical analysis (ESCA), ion scattering spectroscopy (ISS) and electron stimulated desorption (ESD). The changes in the surface composition and chemical states of the surface species generally are subtle for the reductive conditions used. However, significant changes do occur with regard to the amounts and the chemical forms of the hydrogen-containing species remaining after both the 100 and 175 C reductions.

  15. Testing and evaluation of eight decontamination chemicals

    SciTech Connect

    Demmer, R.

    1994-09-01

    This report covers experimental work comparing eight different decontamination chemicals. Seven of these chemicals have some novelty, or are not currently in use at the ICPP. The eighth is a common ICPP decontamination reagent used as a baseline for effective comparison. Decontamination factors, waste generation values, and corrosion rates are tabulated for these chemicals. Recommendations are given for effective methods of non-sodium or low-sodium decontamination chemicals. The two most effective chemical for decontamination found in these test were a dilute hydrofluoric and nitric acid (HF/HNO{sub 3}) mixture and a fluoroboric acid solution. The fluoroboric acid solution (1 molar) was by far the most effective decontamination reagent, but suffered the problem of generating significant final calcine volume. The HF/HNO{sub 3} solution performed a very good decontamination of the SIMCON coupons while generating only small amounts of calcine volume. Concentration variables were also tested, and optimized for these two solutions. Several oxidation/reduction decon chemical systems were also tested. These systems were similar to the TURCO 4502 and TURCO 4521 solutions used for general decontamination at the ICPP. A low sodium alternative, nitric acid/potassium permanganate, to the ``high sodium`` TURCO 4502 was tested extensively, optimized and recommended for general ICPP use. A reductive chemical solution, oxalic acid/nitric acid was also shown to have significant advantages.

  16. Acrylic Tanks for Stunning Chemical Demonstrations

    ERIC Educational Resources Information Center

    Mirholm, Alexander; Ellervik, Ulf

    2009-01-01

    We describe the use of acrylic tanks (400 x 450 x 27 mm) for visualization of chemical demonstrations in aqueous solutions. Examples of well-suited demonstrations are oscillating reactions, pH indicators, photochemical reduction of Lauth's violet, and chemoluminiscent reactions. (Contains 1 figure.)

  17. Microfluidic chemical reaction circuits

    DOEpatents

    Lee, Chung-cheng; Sui, Guodong; Elizarov, Arkadij; Kolb, Hartmuth C.; Huang, Jiang; Heath, James R.; Phelps, Michael E.; Quake, Stephen R.; Tseng, Hsian-rong; Wyatt, Paul; Daridon, Antoine

    2012-06-26

    New microfluidic devices, useful for carrying out chemical reactions, are provided. The devices are adapted for on-chip solvent exchange, chemical processes requiring multiple chemical reactions, and rapid concentration of reagents.

  18. Reduction of patulin during apple juice clarification.

    PubMed

    Bissessur, J; Permaul, K; Odhav, B

    2001-08-01

    Patulin is a mycotoxin produced by a number of molds involved in fruit spoilage. This compound is carcinogenic and teratogenic. Various methods are currently used to reduce the levels of patulin in apple juice, namely, charcoal treatment, chemical preservation (sulfur dioxide), gamma irradiation, fermentation, and trimming of fungus-infected apples. Many of these processes are expensive and time-consuming. Therefore, there is a need to find a convenient and economical process to control patulin levels. This study was undertaken to evaluate the effectiveness of several clarification processes for the reduction of patulin. Clarification was carried out on a laboratory scale. Apple pulp was spiked with patulin, pressed, and clarified using four different processes, namely, fining with bentonite, enzyme (pectinase) treatment, paper filtration, and centrifugation. Patulin was recovered from the clarified juice by liquid-liquid extraction, and solid-phase chromatography was used for sample clean-up prior to analysis by high-performance liquid chromatography (HPLC). The minimum detectable limit using HPLC was 20 microg/liter. Pressing followed by centrifugation resulted in an average toxin reduction of 89%. Total toxin reduction using filtration, enzyme treatment, and fining were 70, 73, and 77%, respectively. Patulin reduction was due to the binding of the toxin to solid substrates that was verified by analyzing the clarified juice as well as the filter cake, pellet, and sediment. The combined concentrations correlated to the spiked concentration. These results reveal that clarification was successful in the reduction of patulin levels in apple juice. However, clarification resulted in high levels of patulin in the pressed pulp after filtration and centrifugation, and this could be harmful if they are used as animal feeds.

  19. Inhibition of microbial arsenate reduction by phosphate.

    PubMed

    Slaughter, Deanne C; Macur, Richard E; Inskeep, William P

    2012-03-20

    The ratio of arsenite (As(III)) to arsenate (As(V)) in soils and natural waters is often controlled by the activity of As-transforming microorganisms. Phosphate is a chemical analog to As(V) and, consequently, may competitively inhibit microbial uptake and enzymatic binding of As(V), thus preventing its reduction to the more toxic, mobile, and bioavailable form - As(III). Five As-transforming bacteria isolated either from As-treated soil columns or from As-impacted soils were used to evaluate the effects of phosphate on As(V) reduction and As(III) oxidation. Cultures were initially spiked with various P:As ratios, incubated for approximately 48 h, and analyzed periodically for As(V) and As(III) concentration. Arsenate reduction was inhibited at high P:As ratios and completely suppressed at elevated levels of phosphate (500 and 1,000 μM; P inhibition constant (K(i))∼20-100 μM). While high P:As ratios effectively shut down microbial As(V) reduction, the expression of the arsenate reductase gene (arsC) was not inhibited under these conditions in the As(V)-reducing isolate, Agrobacterium tumefaciens str. 5B. Further, high phosphate ameliorated As(V)-induced cell growth inhibition caused by high (1mM) As pressure. These results indicate that phosphate may inhibit As(V) reduction by impeding As(V) uptake by the cell via phosphate transport systems or by competitively binding to the active site of ArsC. PMID:21741807

  20. Spectroscopic chemical analysis methods and apparatus

    NASA Technical Reports Server (NTRS)

    Hug, William F. (Inventor); Reid, Ray D. (Inventor)

    2010-01-01

    Spectroscopic chemical analysis methods and apparatus are disclosed which employ deep ultraviolet (e.g. in the 200 nm to 300 nm spectral range) electron beam pumped wide bandgap semiconductor lasers, incoherent wide bandgap semiconductor light emitting devices, and hollow cathode metal ion lasers to perform non-contact, non-invasive detection of unknown chemical analytes. These deep ultraviolet sources enable dramatic size, weight and power consumption reductions of chemical analysis instruments. Chemical analysis instruments employed in some embodiments include capillary and gel plane electrophoresis, capillary electrochromatography, high performance liquid chromatography, flow cytometry, flow cells for liquids and aerosols, and surface detection instruments. In some embodiments, Raman spectroscopic detection methods and apparatus use ultra-narrow-band angle tuning filters, acousto-optic tuning filters, and temperature tuned filters to enable ultra-miniature analyzers for chemical identification. In some embodiments Raman analysis is conducted simultaneously with native fluorescence spectroscopy to provide high levels of sensitivity and specificity in the same instrument.

  1. Spectroscopic chemical analysis methods and apparatus

    NASA Technical Reports Server (NTRS)

    Hug, William F. (Inventor); Reid, Ray D. (Inventor)

    2009-01-01

    Spectroscopic chemical analysis methods and apparatus are disclosed which employ deep ultraviolet (e.g. in the 200 nm to 300 nm spectral range) electron beam pumped wide bandgap semiconductor lasers, incoherent wide bandgap semiconductor light emitting devices, and hollow cathode metal ion lasers to perform non-contact, non-invasive detection of unknown chemical analytes. These deep ultraviolet sources enable dramatic size, weight and power consumption reductions of chemical analysis instruments. Chemical analysis instruments employed in some embodiments include capillary and gel plane electrophoresis, capillary electrochromatography, high performance liquid chromatography, flow cytometry, flow cells for liquids and aerosols, and surface detection instruments. In some embodiments, Raman spectroscopic detection methods and apparatus use ultra-narrow-band angle tuning filters, acousto-optic tuning filters, and temperature tuned filters to enable ultra-miniature analyzers for chemical identification. In some embodiments Raman analysis is conducted simultaneously with native fluorescence spectroscopy to provide high levels of sensitivity and specificity in the same instrument.

  2. Chemical Management System

    1998-10-30

    CMS provides an inventory of all chemicals on order or being held in the laboratory, to provide a specific location for all chemical containers, to ensure that health and safety regulatory codes are being upheld, and to provide PNNL staff with hazardous chemical information to better manage their inventories. CMS is comprised of five major modules: 1) chemical purchasing, 2) chemical inventory, 3) chemical names, properties, and hazard groups, 4) reporting, and 5) system administration.

  3. Nature's chemicals and synthetic chemicals: Comparative toxicology

    SciTech Connect

    Ames, B.N.; Profet, M.; Gold, L.S. )

    1990-10-01

    The toxicology of synthetic chemicals is compared to that of natural chemicals, which represent the vast bulk of the chemicals to which humans are exposed. It is argued that animals have a broad array of inducible general defenses to combat the changing array of toxic chemicals in plant food (nature's pesticides) and that these defenses are effective against both natural and synthetic toxins. Synthetic toxins such as dioxin are compared to natural chemicals, such as indole carbinol (in broccoli) and ethanol. Trade-offs between synthetic and natural pesticides are discussed. The finding that in high-dose tests, a high proportion of both natural and synthetic chemicals are carcinogens, mutagens, teratogens, and clastogens (30-50{percent} for each group) undermines current regulatory efforts to protect public health from synthetic chemicals based on these tests.

  4. Nature's chemicals and synthetic chemicals: comparative toxicology.

    PubMed Central

    Ames, B N; Profet, M; Gold, L S

    1990-01-01

    The toxicology of synthetic chemicals is compared to that of natural chemicals, which represent the vast bulk of the chemicals to which humans are exposed. It is argued that animals have a broad array of inducible general defenses to combat the changing array of toxic chemicals in plant food (nature's pesticides) and that these defenses are effective against both natural and synthetic toxins. Synthetic toxins such as dioxin are compared to natural chemicals, such as indole carbinol (in broccoli) and ethanol. Trade-offs between synthetic and natural pesticides are discussed. The finding that in high-dose tests, a high proportion of both natural and synthetic chemicals are carcinogens, mutagens, teratogens, and clastogens (30-50% for each group) undermines current regulatory efforts to protect public health from synthetic chemicals based on these tests. PMID:2217211

  5. 78 FR 33096 - Agency Forms Undergoing Paperwork Reduction Act Review

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-03

    ... HUMAN SERVICES Centers for Disease Control and Prevention Agency Forms Undergoing Paperwork Reduction Act Review The Centers for Disease Control and Prevention (CDC) publishes a list of information... days of this notice. Proposed Project Spectrum of Flavoring Chemical-Related Lung...

  6. Environmental Optimization Using the WAste Reduction Algorithm (WAR)

    EPA Science Inventory

    Traditionally chemical process designs were optimized using purely economic measures such as rate of return. EPA scientists developed the WAste Reduction algorithm (WAR) so that environmental impacts of designs could easily be evaluated. The goal of WAR is to reduce environme...

  7. Chemical Industry Corrosion Management

    SciTech Connect

    2003-02-01

    Improved Corrosion Management Could Provide Significant Cost and Energy Savings for the Chemical Industry. In the chemical industry, corrosion is often responsible for significant shutdown and maintenance costs.

  8. Setting goals for drug policy: harm reduction or use reduction?

    PubMed

    Caulkins, J P; Reuter, P

    1997-09-01

    Historically, United States drug policy has focused on use reduction; harm reduction is a prominent alternative. This paper aims to provoke and inform more debate about the relative merits of these two. Since harm is not necessarily proportional to use, use reduction and harm reduction differ. Both terms are somewhat ambiguous; precisely defining them clarifies thinking and policy implications. Measures associated with use reduction goals are poor; those associated with harm reduction are even worse. National goals influence the many decentralized individuals who collectively make drug policy; clearly enunciating goals makes some policy choices transparent and goals serve a variety of purposes besides guiding programmatic decisions. We recommend that the overall objective be to minimize the total harm associated with drug production, distribution, consumption and control. Reducing use should be seen as a principal means of attaining that end.

  9. Size reduction machine

    SciTech Connect

    Fricke, V.

    1999-12-15

    The Size Reduction Machine (SRM) is a mobile platform capable of shearing various shapes and types of metal components at a variety of elevations. This shearing activity can be performed without direct physical movement and placement of the shear head by the operator. The base unit is manually moved and roughly aligned to each cut location. The base contains the electronics: hydraulic pumps, servos, and actuators needed to move the shear-positioning arm. The movable arm allows the shear head to have six axes of movement and to cut to within 4 inches of a wall surface. The unit has a slick electrostatic capture coating to assist in external decontamination. Internal contamination of the unit is controlled by a high-efficiency particulate air (HEPA) filter on the cooling inlet fan. The unit is compact enough to access areas through a 36-inch standard door opening. This paper is an Innovative Technology Summary Report designed to provide potential users with the information they need to quickly determine if a technology would apply to a particular environmental management problem. They also are designed for readers who may recommend that a technology be considered by prospective users.

  10. Automatic identification of model reductions for discrete stochastic simulation

    NASA Astrophysics Data System (ADS)

    Wu, Sheng; Fu, Jin; Li, Hong; Petzold, Linda

    2012-07-01

    Multiple time scales in cellular chemical reaction systems present a challenge for the efficiency of stochastic simulation. Numerous model reductions have been proposed to accelerate the simulation of chemically reacting systems by exploiting time scale separation. However, these are often identified and deployed manually, requiring expert knowledge. This is time-consuming, prone to error, and opportunities for model reduction may be missed, particularly for large models. We propose an automatic model analysis algorithm using an adaptively weighted Petri net to dynamically identify opportunities for model reductions for both the stochastic simulation algorithm and tau-leaping simulation, with no requirement of expert knowledge input. Results are presented to demonstrate the utility and effectiveness of this approach.

  11. Reduction of uranium hexafluoride to tetrafluoride by using the hydrogen atoms

    NASA Astrophysics Data System (ADS)

    Aleksandrov, B. P.; Gordon, E. B.; Ivanov, A. V.; Kotov, A. A.; Smirnov, V. E.

    2016-09-01

    We consider the reduction of UF6 to UF4 by chemical reaction with hydrogen atoms originated in the powerful chemical generator. The principal design of such a chemical convertor is described. The results of the mathematical modeling of the thermodynamics and kinetics of the UF6 to UF4 reduction process are analyzed. The few options for the hydrogen atom generator design are proposed. A layout of the experimental setup with the chemical reactor is presented. The high efficiency together with the ability of the process scaling without loss of its efficiency makes this approach to the uranium hexafluoride depletion into tetrafluoride promising for its application in the industry.

  12. Reduction of bromate by granular activated carbon

    SciTech Connect

    Kirisits, M.J.; Snoeyink, V.L.; Kruithof, J.C.

    1998-07-01

    Ozonation of waters containing bromide can lead to the formation of bromate, a probable human carcinogen. Since bromate will be regulated at 10 {micro}g/L by the Stage 1 Disinfectants/Disinfection By-Products Rule, there is considerable interest in finding a suitable method of bromate reduction. Granular activated carbon (GAC) can be used to chemically reduce bromate to bromide, but interference from organic matter and anions present in natural water render this process inefficient. In an effort to improve bromate reduction by GAC, several modifications were made to the GAC filtration process. The use of a biologically active carbon (BAC) filter ahead of a fresh GAC filter with and without preozonation, to remove the biodegradable organic matter, did not substantially improve the bromate removal of the GAC filter. The use of the BAC filter for biological bromate reduction proved to be the most encouraging experiment. By lowering the dissolved oxygen in the influent to the BAC from 8.0 mg/L to 2.0 mg/L, the percent bromate removal increased from 42% to 61%.

  13. Topical fat reduction.

    PubMed

    Greenway, F L; Bray, G A; Heber, D

    1995-11-01

    The fat on women's thighs is more difficult to mobilize due to increased alpha-2 adrenergic receptor activity induced by estrogen. Lipolysis can be initiated through adipocyte receptor stimulation (beta adrenergic) or inhibition (adenosine or alpha-2 adrenergic) or by inhibition of phosphodiesterase. Since many women desire regional thigh fat loss, a series of clinical trials were initiated using one thigh as a double-blinded control. Trial #1: Five overweight women had injections of isoproterenol at intervals around the thigh three times a week for 4 weeks with diet and walking. Trial #2: Five overweight woman had ointment containing forskolin, yohimbine and aminophylline applied to the thigh five times a week for 4 weeks after hypertonic warm soaks with a diet and walking. Trial #3: Eighteen overweight women were divided into three groups of six and trial #2 was repeated with each agent alone vs. placebo using forskolin, yohimbine or aminophylline in separate ointments. Trial #4: Thirty overweight women had 10% aminophylline ointment applied to the thigh five times a week for 6 weeks with diet and walking. Chemistry panel, theophylline level and patch testing were performed. Trial #5: Twelve women had trial #4 repeated with 2% aminophylline cream without a diet or walking. Trial #6: Trial #5 was repeated with 0.5% aminophylline cream. All trials except yohimbine ointment gave significantly more girth loss from the treated thigh (p < 0.05 to p < 0.001). Chemistry panel showed no toxicity. Theophylline was undetectable and patch testing was negative. We conclude that topical fat reduction for women's thighs can be achieved without diet or exercise. PMID:8697059

  14. Model reduction for flexible structures

    NASA Technical Reports Server (NTRS)

    Gawronski, Wodek; Juang, Jer-Nan

    1990-01-01

    Several conditions for a near-optimal reduction of general dynamic systems are presented focusing on the reduction in balanced and modal coordinates. It is shown that model and balanced reductions give very different results for the flexible structure with closely-spaced natural frequencies. In general, balanced reduction is found to give better results. A robust model reduction technique was developed to study the sensitivity of modeling error to variations in the damping of a structure. New concepts of grammians defined over a finite time and/or a frequency interval are proposed including computational procedures for evaluating them. Application of the model reduction technique to these grammians is considered to lead to a near-optimal reduced model which closely reproduces the full system output in the time and/or frequency interval.

  15. Graphite Oxide: Structure, Reduction and Applications

    NASA Astrophysics Data System (ADS)

    Gao, Wei

    This thesis proposes a modified structure model for graphite oxide (GO), an important precursor in graphene chemistry, develops a new strategy to convert GO back to graphene-like structure, and demonstrates its possible applications in both water purification and supercapacitor technologies. GO, a nontraditional compound first obtained from graphite oxidation over 150 years ago, is now becoming an important player in the production of graphene-based materials, which has high technological relevance. GO structure and reduction have been vigorously investigated, but its precise chemical structure still remains obscure, and the complete restoration of the sp2 carbon lattice has not yet been achieved. In our work, solid state 13C NMR (MAS) analysis offered a piece of evidence for five or six-membered ring lactol structure existing in GO that had never been assigned before, leading to a modified Lerf-Klinowski model for GO. A three-step reduction strategy, involving sodium borohydride (NaBH4), sulfuric acid, and high temperature thermal annealing, described in the thesis, successfully reduced GO back to chemically converted graphene (CCG) with the lowest heteroatom abundance among all those previously reported. In addition to the chemical significance of graphene/CCG production, GO and its derivatives were used as novel adsorbents in water purification. GO-coated sand showed higher retention than ordinary sand for both Rhodamine B and mercuric ion (Hg2+) contaminants in water. Further functionalization of GO with thiophenol resulted in better adsorption capacity toward Hg2+ than that of activated carbon. In addition, free-standing films of GO were treated and reduced with a CO 2 laser beam into different conductive reduced GO (RGO) patterns, and directly used as supercapacitor devices which showed good cyclic stability and energy storage capacities comparable to that of existing thin film ultracapacitors. GO turned out to be a solid electrolyte with anisotropic proton

  16. The chemical life(1).

    PubMed

    Hodges, Nathan

    2015-01-01

    You write this narrative autoethnography to open up a conversation about our chemical lives. You go through your day with chemical mindfulness, questioning taken-for-granted ideas about natural and artificial, healthy and unhealthy, dependency and addiction, trying to understand the chemical messages we consume through the experiences of everyday life. You reflect on how messages about chemicals influence and structure our lives and why some chemicals are celebrated and some are condemned. Using a second-person narrative voice, you show how the personal is relational and the chemical is cultural. You write because you seek a connection, a chemical bond. PMID:24905820

  17. The chemical life(1).

    PubMed

    Hodges, Nathan

    2015-01-01

    You write this narrative autoethnography to open up a conversation about our chemical lives. You go through your day with chemical mindfulness, questioning taken-for-granted ideas about natural and artificial, healthy and unhealthy, dependency and addiction, trying to understand the chemical messages we consume through the experiences of everyday life. You reflect on how messages about chemicals influence and structure our lives and why some chemicals are celebrated and some are condemned. Using a second-person narrative voice, you show how the personal is relational and the chemical is cultural. You write because you seek a connection, a chemical bond.

  18. Emerging Community Noise Reduction Approaches

    NASA Technical Reports Server (NTRS)

    Envia, Edmane

    2012-01-01

    An overview of the current NASA research portfolio in the area of aircraft noise reduction is presented. The emphasis of the research described herein is on meeting the aggressive near- and mid-term national goals for reducing aircraft noise emissions, which NASA internal studies have shown to be feasible using noise reduction technologies currently being developed in-house or in partnership with NASA s industry and academic partners. While NASA has an active research effort in airframe noise reduction, this overview focuses on propulsion noise reduction only.

  19. Cochlear implant optimized noise reduction.

    PubMed

    Mauger, Stefan J; Arora, Komal; Dawson, Pam W

    2012-12-01

    Noise-reduction methods have provided significant improvements in speech perception for cochlear implant recipients, where only quality improvements have been found in hearing aid recipients. Recent psychoacoustic studies have suggested changes to noise-reduction techniques specifically for cochlear implants, due to differences between hearing aid recipient and cochlear implant recipient hearing. An optimized noise-reduction method was developed with significantly increased temporal smoothing of the signal-to-noise ratio estimate and a more aggressive gain function compared to current noise-reduction methods. This optimized noise-reduction algorithm was tested with 12 cochlear implant recipients over four test sessions. Speech perception was assessed through speech in noise tests with three noise types; speech-weighted noise, 20-talker babble and 4-talker babble. A significant speech perception improvement using optimized noise reduction over standard processing was found in babble noise and speech-weighted noise and over a current noise-reduction method in speech-weighted noise. Speech perception in quiet was not degraded. Listening quality testing for noise annoyance and overall preference found significant improvements over the standard processing and over a current noise-reduction method in speech-weighted and babble noise types. This optimized method has shown significant speech perception and quality improvements compared to the standard processing and a current noise-reduction method.

  20. PINS chemical identification software

    DOEpatents

    Caffrey, Augustine J.; Krebs, Kennth M.

    2004-09-14

    An apparatus and method for identifying a chemical compound. A neutron source delivers neutrons into the chemical compound. The nuclei of chemical elements constituting the chemical compound emit gamma rays upon interaction with the neutrons. The gamma rays are characteristic of the chemical elements constituting the chemical compound. A spectrum of the gamma rays is generated having a detection count and an energy scale. The energy scale is calibrated by comparing peaks in the spectrum to energies of pre-selected chemical elements in the spectrum. A least-squares fit completes the calibration. The chemical elements constituting the chemical compound can be readily determined, which then allows for identification of the chemical compound.

  1. Optimising resources by reduction: the FRAME Reduction Committee.

    PubMed

    Vaughan, Sylvia

    2004-06-01

    The Fund for the Replacement of Animals in Medical Experiments (FRAME) Reduction Committee, formed in 1998, comprises experienced professionals in the fields of statistics, experimental design, animal welfare and alternatives. The committee undertakes projects designed to contribute to reduction by addressing the implementation of recommendations made at an European Centre for the Validation of Alternative Methods (ECVAM) workshop on reducing the use of laboratory animals. The use of improved experimental design and statistical analysis techniques are key means of achieving reduction. Literature surveys have shown that there is scope for improvement in these areas. Projects include organising workshops that explain how these techniques can be used to achieve reduction, the creation of guidelines for journal editors and the compilation of a directory of training material on experimental design and statistical analysis. The first FRAME Reduction Committee international symposium will be held in October 2002. PMID:23577468

  2. Concerted reactions of polynuclear metalloenzymes and their functional chemical models

    NASA Astrophysics Data System (ADS)

    Dzhabiev, T. S.; Shilov, A. E.

    2011-03-01

    The mechanisms of the many-electron oxidation of water by a chemical model of the manganese oxidase cofactor in photosynthesis photosystem II (manganese(IV) clusters) and nitrogen reduction in chemical models of nitrogenase cofactor (vanadium(II) and molybdenum(III) clusters) were considered. The hypothesis was suggested according to which polynuclear enzyme cofactors and their functional chemical models performed two important functions, catalyzed noncomplementary processes and effected many-substrate concerted reactions with decreased activation energies.

  3. Further weight reduction of applications in long glass reinforced polymers

    NASA Astrophysics Data System (ADS)

    Yanev, A.; Schijve, W.; Martin, C.; Brands, D.

    2014-05-01

    Long glass reinforced materials are broadly used in the automotive industry due to their good mechanical performance, competitive price and options for functional integration in order to reduce weight. With rapidly changing environmental requirements, a demand for further weight reduction is growing constantly. Designs in LGF-PP can bring light weight solutions in combination with system cost improvement. There are quite some possibilities for applying weight reduction technologies nowadays. These technologies have to be evaluated based on weight reduction potential, but also on mechanical performance of the end application, where the latter is often the key to success. Different weight reduction technologies are applied to SABIC®STAMAX{trade mark, serif} material, a long glass fiber reinforced polypropylene (LGF-PP), in order to investigate and define best application performance. These techniques include: chemical foaming, physical foaming and thin wall applications. Results from this research will be presented, giving a guideline for your development.

  4. Green Rust Reduction of Chromium Part 2: Comparison of Heterogeneous and Homogeneous Chromate Reduction

    SciTech Connect

    Wander, Matthew C.; Schoonen, Martin A.

    2010-10-07

    White and green rusts are the active chemical reagents of buried scrap iron pollutant remediation. In this work, a comparison of the initial electron-transfer step for the reduction of CrO{sub 4}{sup -2} by Fe{sub (aq)}{sup 2+} and Fe(OH){sub 2}(s) is presented. Using hybrid density functional theory and Hartree-Fock cluster calculations for the aqueous reaction, the rate constant for the homogeneous reduction of chromium by ferrous iron was determined to be 5 x 10{sup -2} M{sup -1} s{sup -1} for the initial electron transfer. Using a combination of Hartree-Fock slab and cluster calculations for the heterogeneous reaction, the initial electron transfer for the heterogeneous reduction of chromium by ferrous iron was determined to be 1 x 10{sup 2} s{sup -1}. The difference in rates is driven by the respective free energies of reaction: 33.4 vs -653.2 kJ/mol. This computational result is apparently the opposite of what has been observed experimentally, but further analysis suggests that these results are fully convergent with experiment. The experimental heterogeneous rate is limited by surface passivation from slow intersheet electron transfer, while the aqueous reaction may be an autocatalytic heterogeneous reaction involving the iron oxyhydroxide product. As a result, it is possible to produce a clear model of the pollutant reduction reaction sequence for these two reactants.

  5. Noise Reduction by Signal Accumulation

    ERIC Educational Resources Information Center

    Kraftmakher, Yaakov

    2006-01-01

    The aim of this paper is to show how the noise reduction by signal accumulation can be accomplished with a data acquisition system. This topic can be used for student projects. In many cases, the noise reduction is an unavoidable part of experimentation. Several techniques are known for this purpose, and among them the signal accumulation is the…

  6. Reduction-Fired Seedpod Bowls.

    ERIC Educational Resources Information Center

    Beyke, Rod

    2001-01-01

    Focuses on a reduction-firing process with an aim of producing high-quality blackware similar to the black-on-black pottery of Maria Martinez and other American Indian potters. Includes a lesson on creating reduction-fired seedpod bowls, lists of instructional resources and materials, and the objectives and evaluation. (CMK)

  7. The reduction of NO{sub x} by HNCO

    SciTech Connect

    Brown, N.J.; Garay, J.

    1992-10-01

    A chemical mechanism for the reduction of NO{sub x} by HNCO has been constructed to model NO{sub x} reduction in exhausts typical of natural gas combustion with the addition of radical boosters (fuel). Variables considered were the initial concentrations of NO, NO{sub 2}, CO, O{sub 2}, CH{sub 4}, H{sub 2}, and HNCO as well as initial temperatures. The chemical model was validated by comparing results with earlier model calculations of Miller and Bowman and with the experiments of Caton and Siebers and Lyon and Cole. Agreement with experiments was satisfactory. The reduction chemistry must be preceded by thermal ignition chemistry which generates radicals. The lowest temperature for which ignition occurs is the optimum temperature for reduction and defines the beginning of the temperature window. Reduction was not achieved for the ``natural gas exhaust`` for a reasonable residence time. Additional H{sub 2} added to the exhaust mixture enhanced reduction, but the addition of CO and CH{sub 4} did not. Under some conditions the computed sensitivity coefficient for nitrogen species and temperature exhibited self-similarity. Four reaction paths were identified which controlled the fate of the NO: the conversion of NO to NO{sub 2} via HO{sub 2}, the conversion of NO{sub 2} to NO via reaction with H or O, the reduction of NO via NCO, and the reduction of NO from reactions with NH{sub i} species. The relative importance of the four was determined by the initial conditions.

  8. Electrohydrodynamic atomization (EHDA) assisted wet chemical synthesis of nickel nanoparticles

    SciTech Connect

    Barzegar Vishlaghi, M.; Farzalipour Tabriz, M.; Mohammad Moradi, O.

    2012-07-15

    Highlights: ► Electrohydrodynamic atomization (EHDA) assisted chemical synthesis of nickel nanoparticles is reported. ► Substituting water with non-aqueous media prevents the formation of nickel hydroxide. ► Size of particles decreased from 10 to 20 nm down to 2–4 nm by using multi-jet mode. ► Synthesized nanoparticles have diffraction patterns similar to amorphous materials. -- Abstract: In this study nickel nanoparticles were prepared via chemical reduction of nickel acetate using sodium borohydride using electrohydrodynamic atomization (EHDA) technique. This technique was used to spray a finely dispersed aerosol of nickel precursor solution into the reductive bath. Obtained particles were characterized by means of X-ray diffraction (XRD), UV–Visible spectroscopy, and transmission electron microscopy (TEM). Results confirmed the formation of nickel nanoparticles and showed that applying EHDA technique to chemical reduction method results in producing smaller particles with narrower size distribution in comparison with conventional reductive precipitation method.

  9. Nitrite reduction in Veillonella alcalescens.

    PubMed Central

    Yordy, D M; Delwiche, E A

    1979-01-01

    Nitrite reduction was examined in Veillonella alcalescens C-1, and obligate anaerobe with an ATP-yielding nitrate-reducing system. Hydrogen donors for nitrite reduction included hydrosulfite, hydrogen gas, and pyruvate, but not pyridine nucleotides, in the presnece or absence of flavins. Pyruvate-linked nitrite reduction was not inhibited by 4,4,4-trifluoro-1-(2-thienyl) 1,3-butanedione, dicoumarol, or 2-heptyl-4-hydroxy-quinoline-N-oxide. The noninvolvement of membrane-bound factors was supported by the fact that 100% of pyruvate-linked activity remained in the soluble fraction after fractionation of crude extracts by ultracentrifugation. Using DEAE-cellulose column chromatography, however, the participation of ferredoxin in nitrite reduction was demonstrated. The product of nitrite reduction appeared to be ammonia, as determined from H2-to-NO2- ratios. Nitrite reductase was induced by nitrate or nitrite and was repressed by increased levels of reduced nitrogenous compounds. PMID:422515

  10. Ultrafiltration Membrane Module Virus Reduction at Different Fluxes, and with a Cut Fiber

    EPA Science Inventory

    NSF International evaluated The Dow Chemical Company SFD-2880 UF membrane module for MS2 reduction at four different fluxes, and also with and without a cut fiber, to compare MS2 log reduction under the different scenarios. All tests were conducted in accordance with the U.S. En...

  11. DRAG REDUCTION WITH SUPERHYDROPHOBIC RIBLETS

    SciTech Connect

    Barbier, Charlotte N; D'Urso, Brian R; Jenner, Elliot

    2012-01-01

    Samples combining riblets and superhydrophobic surfaces are fabricated at University of Pittsburgh and their drag reduction properties are studied at the Center for Nanophase Materials Sciences (CNMS) in Oak Ridge National Laboratory with a commercial cone-and-plate rheometer. In parallel to the experiments, numerical simulations are performed in order to estimate the slip length at high rotational speed. For each sample, a drag reduction of at least 5% is observed in both laminar and turbulent regime. At low rotational speed, drag reduction up to 30% is observed with a 1 mm deep grooved sample. As the rotational speed increases, a secondary flow develops causing a slight decrease in drag reductions. However, drag reduction above 15% is still observed for the large grooved samples. In the turbulent regime, the 100 microns grooved sample becomes more efficient than the other samples in drag reduction and manages to sustain a drag reduction above 15%. Using the simulations, the slip length of the 100 micron grooved sample is estimated to be slightly above 100 micron in the turbulent regime.

  12. Technologies for Aircraft Noise Reduction

    NASA Technical Reports Server (NTRS)

    Huff, Dennis L.

    2006-01-01

    Technologies for aircraft noise reduction have been developed by NASA over the past 15 years through the Advanced Subsonic Technology (AST) Noise Reduction Program and the Quiet Aircraft Technology (QAT) project. This presentation summarizes highlights from these programs and anticipated noise reduction benefits for communities surrounding airports. Historical progress in noise reduction and technologies available for future aircraft/engine development are identified. Technologies address aircraft/engine components including fans, exhaust nozzles, landing gear, and flap systems. New "chevron" nozzles have been developed and implemented on several aircraft in production today that provide significant jet noise reduction. New engines using Ultra-High Bypass (UHB) ratios are projected to provide about 10 EPNdB (Effective Perceived Noise Level in decibels) engine noise reduction relative to the average fleet that was flying in 1997. Audio files are embedded in the presentation that estimate the sound levels for a 35,000 pound thrust engine for takeoff and approach power conditions. The predictions are based on actual model scale data that was obtained by NASA. Finally, conceptual pictures are shown that look toward future aircraft/propulsion systems that might be used to obtain further noise reduction.

  13. Personal Chemical Exposure informatics

    EPA Science Inventory

    Chemical Exposure science is the study of human contact with chemicals (from manufacturing facilities, everyday products, waste) occurring in their environments and advances knowledge of the mechanisms and dynamics of events that cause or prevent adverse health outcomes. (adapted...

  14. Floor Chemical Basics.

    ERIC Educational Resources Information Center

    Shaw, Richard

    1998-01-01

    Discusses the issues to consider when selecting floor-care chemicals, including the floor-finish systems for hard-surface floors and the care of carpeted floors. Provides thoughts on cleaning chemical usage and environmental awareness. (GR)

  15. Chemicals Industry Vision

    SciTech Connect

    none,

    1996-12-01

    Chemical industry leaders articulated a long-term vision for the industry, its markets, and its technology in the groundbreaking 1996 document Technology Vision 2020 - The U.S. Chemical Industry. (PDF 310 KB).

  16. Tobacco and chemicals (image)

    MedlinePlus

    Some of the chemicals associated with tobacco smoke include ammonia, carbon dioxide, carbon monoxide, propane, methane, acetone, hydrogen cyanide and various carcinogens. Other chemicals that are associated with chewing ...

  17. Capacitive chemical sensor

    DOEpatents

    Manginell, Ronald P; Moorman, Matthew W; Wheeler, David R

    2014-05-27

    A microfabricated capacitive chemical sensor can be used as an autonomous chemical sensor or as an analyte-sensitive chemical preconcentrator in a larger microanalytical system. The capacitive chemical sensor detects changes in sensing film dielectric properties, such as the dielectric constant, conductivity, or dimensionality. These changes result from the interaction of a target analyte with the sensing film. This capability provides a low-power, self-heating chemical sensor suitable for remote and unattended sensing applications. The capacitive chemical sensor also enables a smart, analyte-sensitive chemical preconcentrator. After sorption of the sample by the sensing film, the film can be rapidly heated to release the sample for further analysis. Therefore, the capacitive chemical sensor can optimize the sample collection time prior to release to enable the rapid and accurate analysis of analytes by a microanalytical system.

  18. Chemical Transformation Simulator

    EPA Science Inventory

    The Chemical Transformation Simulator (CTS) is a web-based, high-throughput screening tool that automates the calculation and collection of physicochemical properties for an organic chemical of interest and its predicted products resulting from transformations in environmental sy...

  19. Chemical Industry Bandwidth Study

    SciTech Connect

    none,

    2006-12-01

    The Chemical Bandwidth Study provides a snapshot of potentially recoverable energy losses during chemical manufacturing. The advantage of this study is the use of "exergy" analysis as a tool for pinpointing inefficiencies.

  20. Geometric Quantization and Foliation Reduction

    NASA Astrophysics Data System (ADS)

    Skerritt, Paul

    A standard question in the study of geometric quantization is whether symplectic reduction interacts nicely with the quantized theory, and in particular whether "quantization commutes with reduction." Guillemin and Sternberg first proposed this question, and answered it in the affirmative for the case of a free action of a compact Lie group on a compact Kahler manifold. Subsequent work has focused mainly on extending their proof to non-free actions and non-Kahler manifolds. For realistic physical examples, however, it is desirable to have a proof which also applies to non-compact symplectic manifolds. In this thesis we give a proof of the quantization-reduction problem for general symplectic manifolds. This is accomplished by working in a particular wavefunction representation, associated with a polarization that is in some sense compatible with reduction. While the polarized sections described by Guillemin and Sternberg are nonzero on a dense subset of the Kahler manifold, the ones considered here are distributional, having support only on regions of the phase space associated with certain quantized, or "admissible", values of momentum. We first propose a reduction procedure for the prequantum geometric structures that "covers" symplectic reduction, and demonstrate how both symplectic and prequantum reduction can be viewed as examples of foliation reduction. Consistency of prequantum reduction imposes the above-mentioned admissibility conditions on the quantized momenta, which can be seen as analogues of the Bohr-Wilson-Sommerfeld conditions for completely integrable systems. We then describe our reduction-compatible polarization, and demonstrate a one-to-one correspondence between polarized sections on the unreduced and reduced spaces. Finally, we describe a factorization of the reduced prequantum bundle, suggested by the structure of the underlying reduced symplectic manifold. This in turn induces a factorization of the space of polarized sections that agrees

  1. Fan Noise Reduction: An Overview

    NASA Technical Reports Server (NTRS)

    Envia, Edmane

    2001-01-01

    Fan noise reduction technologies developed as part of the engine noise reduction element of the Advanced Subsonic Technology Program are reviewed. Developments in low-noise fan stage design, swept and leaned outlet guide vanes, active noise control, fan flow management, and scarfed inlet are discussed. In each case, a description of the method is presented and, where available, representative results and general conclusions are discussed. The review concludes with a summary of the accomplishments of the AST-sponsored fan noise reduction research and a few thoughts on future work.

  2. Subsolidus reduction of lunar spinels.

    NASA Technical Reports Server (NTRS)

    Haggerty, S. E.

    1971-01-01

    Discussion of evidence that some lunar basalts must have exceeded the lower limit of crystallization oxygen fugacity (fO2) by several orders of magnitude. The evidence is based primarily on the decomposition of Cr-Al-ulvospinel, and is further supported in one case by the decomposition of olivine. The data suggest that some rocks have undergone intense nonequilibrium subsolidus reduction. The reduction phenomenon is widespread, and is considered to have developed either during initial deuteric cooling or as a result of a postcrystallization reduction event.

  3. Reduction of INTEC Analytical Radioactive Liquid Wastes

    SciTech Connect

    V. J. Johnson; J. S. Hu; A. G. Chambers

    1999-06-01

    This report details the evaluation of the reduction in radioactive liquid waste from the analytical laboratories sent to the Process Effluent Waste system (deep tanks). The contributors are the Analytical Laboratories Department (ALD), the Waste Operations Department, the laboratories at CPP-637, and natural run off. Other labs were contacted to learn the methods used and if any new technologies had emerged. A waste generation database was made from the current methods in used in the ALD. From this database, methods were targeted to reduce waste. Individuals were contacted on ways to reduce waste. The results are: a new method generating much less waste, several methods being handled differently, some cleaning processes being changed to reduce waste, and changes to reduce chemicals to waste.

  4. Reduction of INTEC Analytical Radioactive Liquid Waste

    SciTech Connect

    Johnson, Virgil James; Hu, Jian Sheng; Chambers, Andrea

    1999-06-01

    This report details the evaluation of the reduction in radioactive liquid waste from the analytical laboratories sent to the Process Effluent Waste system (deep tanks). The contributors are the Analytical Laboratories Department (ALD), the Waste Operations Department, the laboratories at CPP-637, and natural run off. Other labs were contacted to learn of methods used and if any new technologies had emerged. A waste generation database was made from the current methods in use in the ALD. From this database, methods were targeted to reduce waste. Individuals were contacted on ways to reduce waste. The results are: a new method generating much less waste, several methods being handled differently, some cleaning processes being changed to reduce waste, and changes to reduce chemicals to waste.

  5. Background reduction of a spherical gaseous detector

    SciTech Connect

    Fard, Ali Dastgheibi; Loaiza, Pia; Piquemal, Fabrice; Giomataris, Ioannis; Gray, David; Gros, Michel; Magnier, Patrick; Navick, Xavier-François

    2015-08-17

    The Spherical gaseous detector (or Spherical Proportional Counter, SPC) is a novel type of detector. It consists of a large spherical volume filled with gas, using a single detection readout channel. The detector allows 100 % detection efficiency. SEDINE is a low background version of SPC installed at the Laboratoire Souterrain de Modane (LSM) underground laboratory (4800 m.w.e) looking for rare events at very low energy threshold, below 100 eV. This work presents the details on the chemical cleaning to reduce internal {sup 210}Pb surface contamination on the copper vessel and the external radon reduction achieved via circulation of pure air inside anti-radon tent. It will be also show the radon measurement of pure gases (Ar, N, Ne, etc) which are used in the underground laboratory for the low background experiments.

  6. Background reduction of a spherical gaseous detector

    NASA Astrophysics Data System (ADS)

    Fard, Ali Dastgheibi; Loaiza, Pia; Piquemal, Fabrice; Giomataris, Ioannis; Gray, David; Gros, Michel; Magnier, Patrick; Navick, Xavier-François; Savvidis, Ilias

    2015-08-01

    The Spherical gaseous detector (or Spherical Proportional Counter, SPC) is a novel type of detector. It consists of a large spherical volume filled with gas, using a single detection readout channel. The detector allows 100 % detection efficiency. SEDINE is a low background version of SPC installed at the Laboratoire Souterrain de Modane (LSM) underground laboratory (4800 m.w.e) looking for rare events at very low energy threshold, below 100 eV. This work presents the details on the chemical cleaning to reduce internal 210Pb surface contamination on the copper vessel and the external radon reduction achieved via circulation of pure air inside anti-radon tent. It will be also show the radon measurement of pure gases (Ar, N, Ne, etc) which are used in the underground laboratory for the low background experiments.

  7. Computing Equilibrium Chemical Compositions

    NASA Technical Reports Server (NTRS)

    Mcbride, Bonnie J.; Gordon, Sanford

    1995-01-01

    Chemical Equilibrium With Transport Properties, 1993 (CET93) computer program provides data on chemical-equilibrium compositions. Aids calculation of thermodynamic properties of chemical systems. Information essential in design and analysis of such equipment as compressors, turbines, nozzles, engines, shock tubes, heat exchangers, and chemical-processing equipment. CET93/PC is version of CET93 specifically designed to run within 640K memory limit of MS-DOS operating system. CET93/PC written in FORTRAN.

  8. Chemicals for worldwide aquaculture

    USGS Publications Warehouse

    Schnick, R.A.

    1991-01-01

    Regulations and therapeutants or other safe chemicals that are approved or acceptable for use in the aquaculture industry in the US, Canada, Europe and Japan are presented, discussing also compounds that are unacceptable for aquaculture. Chemical use practices that could affect public health are considered and details given regarding efforts to increase the number of registered and acceptable chemicals.

  9. Toxicology and Chemical Safety.

    ERIC Educational Resources Information Center

    Hall, Stephen K.

    1983-01-01

    Topics addressed in this discussion of toxicology and chemical safety include routes of exposure, dose/response relationships, action of toxic substances, and effects of exposure to chemicals. Specific examples are used to illustrate the principles discussed. Suggests prudence in handling any chemicals, whether or not toxicity is known. (JN)

  10. Reductive Degradation: Versatile, Low Cost.

    ERIC Educational Resources Information Center

    Water and Sewage Works, 1979

    1979-01-01

    This article discusses the use of reductive degradation as an economical and effective treatment of chlorinated hydrocarbons. Comparisons with activated carbon treatment show lower capital equipment and treatment costs. (CS)

  11. Biological effects of ozone reduction

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The effects of increased UV radiation on the biosphere are described with ongoing research, and research areas that should be investigated. Some mention is also made of the potential climatic effects of ozone reduction on agriculture and the biosphere.

  12. Hydride Reduction by a Sodium Hydride–Iodide Composite

    PubMed Central

    Too, Pei Chui; Chan, Guo Hao; Tnay, Ya Lin

    2016-01-01

    Abstract Sodium hydride (NaH) is widely used as a Brønsted base in chemical synthesis and reacts with various Brønsted acids, whereas it rarely behaves as a reducing reagent through delivery of the hydride to polar π electrophiles. This study presents a series of reduction reactions of nitriles, amides, and imines as enabled by NaH in the presence of LiI or NaI. This remarkably simple protocol endows NaH with unprecedented and unique hydride‐donor chemical reactivity. PMID:26878823

  13. Fe Isotope Fractionation During Fe(III) Reduction to Fe(II)

    NASA Astrophysics Data System (ADS)

    Baker, E. A.; Greene, S.; Hardin, E. E.; Hodierne, C. E.; Rosenberg, A.; John, S.

    2014-12-01

    The redox chemistry of Fe(III) and Fe(II) is tied to a variety of earth processes, including biological, chemical, or photochemical reduction of Fe(III) to Fe(II). Each process may fractionate Fe isotopes, but the magnitudes of the kinetic isotope effects have not been greatly explored in laboratory conditions. Here, we present the isotopic fractionation of Fe during reduction experiments under a variety of experimental conditions including photochemical reduction of Fe(III) bound to EDTA or glucaric acid, and chemical reduction of Fe-EDTA by sodium dithionite, hydroxylamine hydrochloride, Mn(II), and ascorbic acid. A variety of temperatures and pHs were tested. In all experiments, Fe(III) bound to an organic ligand was reduced in the presence of ferrozine. Ferrozine binds with Fe(II), forming a purple complex which allows us to measure the extent of reaction. The absorbance of the experimental solutions was measured over time to determine the Fe(II)-ferrozine concentration and thus the reduction rate. After about 5% of the Fe(III) was reduced, Fe(III)-EDTA and Fe(II)-ferrozine were separated using a C-18 column to which Fe(II)-ferrozine binds. The Fe(II) was eluted and purified through anion exchange chromatography for analysis of δ56Fe by MC-ICPMS. Preliminary results show that temperature and pH both affect reduction rate. All chemical reductants tested reduce Fe(III) at a greater rate as temperature increases. The photochemical reductant EDTA reduces Fe(III) at a greater rate under more acidic conditions. Comparison of the two photochemical reductants shows that glucaric acid reduces Fe(III) significantly faster than EDTA. For chemical reduction, the magnitude of isotopic fractionation depends on the reductant used. Temperature and pH also affect the isotopic fractionation of Fe. Experiments using chemical reductants show that an increase in temperature at low temperatures produces lighter 56Fe ratios, while at high temperatures some reductants produce heavier

  14. 2dfdr: Data reduction software

    NASA Astrophysics Data System (ADS)

    AAO software Team

    2015-05-01

    2dfdr is an automatic data reduction pipeline dedicated to reducing multi-fibre spectroscopy data, with current implementations for AAOmega (fed by the 2dF, KOALA-IFU, SAMI Multi-IFU or older SPIRAL front-ends), HERMES, 2dF (spectrograph), 6dF, and FMOS. A graphical user interface is provided to control data reduction and allow inspection of the reduced spectra.

  15. Chromium reduction in Pseudomonas putida.

    PubMed Central

    Ishibashi, Y; Cervantes, C; Silver, S

    1990-01-01

    Reduction of hexavalent chromium (chromate) to less-toxic trivalent chromium was studied by using cell suspensions and cell-free supernatant fluids from Pseudomonas putida PRS2000. Chromate reductase activity was associated with soluble protein and not with the membrane fraction. The crude enzyme activity was heat labile and showed a Km of 40 microM CrO4(2-). Neither sulfate nor nitrate affected chromate reduction either in vitro or with intact cells. PMID:2389940

  16. Phosphine from rocks: mechanically driven phosphate reduction?

    PubMed

    Glindemann, Dietmar; Edwards, Marc; Morgenstern, Peter

    2005-11-01

    Natural rock and mineral samples released trace amounts of phosphine during dissolution in mineral acid. An order of magnitude more phosphine (average 1982 ng PH3 kg rock and maximum 6673 ng PH3/kg rock) is released from pulverized rock samples (basalt, gneiss, granite, clay, quartzitic pebbles, or marble). Phosphine was correlated to hardness and mechanical pulverization energy of the rocks. The yield of PH3 ranged from 0 to 0.01% of the total P content of the dissolved rock. Strong circumstantial evidence was gathered for reduction of phosphate in the rock via mechanochemical or "tribochemical" weathering at quartz and calcite/marble inclusions. Artificial reproduction of this mechanism by rubbing quartz rods coated with apatite-phosphate to the point of visible triboluminescence, led to detection of more than 70 000 ng/kg PH3 in the apatite. This reaction pathway may be considered a mechano-chemical analogue of phosphate reduction from lightning or electrical discharges and may contribute to phosphine production via tectonic forces and processing of rocks.

  17. Substance abuse and developments in harm reduction.

    PubMed

    Cheung, Y W

    2000-06-13

    A drug is a substance that produces a psychoactive, chemical or medicinal effect on the user. The psychoactive effect of mood-altering drugs is modulated by the user's perception of the risks of drug use, his or her ability to control drug use and the demographic, socioeconomic and cultural context. The ability to control drug use may vary along a continuum from compulsive use at one end to controlled use at the other. The "drug problem" has been socially constructed, and the presence of a moral panic has led to public support for the prohibitionist approach. The legalization approach has severely attacked the dominant prohibitionist approach but has failed to gain much support in society because of its extreme libertarian views. The harm reduction approach, which is based on public health principles, avoids the extremes of value-loaded judgements on drug use and focuses on the reduction of drug-related harm through pragmatic and low-threshold programs. This approach is likely to be important in tackling the drug problem in the 21st century.

  18. Substance abuse and developments in harm reduction

    PubMed Central

    Cheung, Y W

    2000-01-01

    A drug is a substance that produces a psychoactive, chemical or medicinal effect on the user. The psychoactive effect of mood-altering drugs is modulated by the user's perception of the risks of drug use, his or her ability to control drug use and the demographic, socioeconomic and cultural context. The ability to control drug use may vary along a continuum from compulsive use at one end to controlled use at the other. The "drug problem" has been socially constructed, and the presence of a moral panic has led to public support for the prohibitionist approach. The legalization approach has severely attacked the dominant prohibitionist approach but has failed to gain much support in society because of its extreme libertarian views. The harm reduction approach, which is based on public health principles, avoids the extremes of value-loaded judgements on drug use and focuses on the reduction of drug-related harm through pragmatic and low-threshold programs. This approach is likely to be important in tackling the drug problem in the 21st century. PMID:10870502

  19. Key factors influencing rates of heterotrophic sulfate reduction in hydrothermal massive sulfide deposits

    NASA Astrophysics Data System (ADS)

    Frank, K. L.; Rogers, D.; Girguis, P. R.

    2012-12-01

    Despite sulfate reduction's ubiquity in marine systems, relatively little is known about how environmental or ecological factors influence rates of sulfate reduction. While numerous studies have considered how sulfate reduction and methanogenesis compete for reductants in natural and human-made systems, less is known about how temperature or metabolite concentration, such as sulfate and sulfide concentrations, affects rates of sulfate reduction. Here we use a factorial experimental design to evaluate the effects of key variables on sulfate reduction kinetics in sulfide deposits recovered from hydrothermal vents in the Main Endeavor Field, Juan de Fuca ridge. Microbial sulfate reduction rates were measured by 35-S tracer techniques over a range of environmentally relevant chemical conditions (pH, H2S, SO42-, and organic carbon concentrations) and temperatures (4, 50 and 90°C). Maximum sulfate reduction rates were observed at 50°C, and sulfate reduction rates had significant positive correlations with increasing sulfide, pH and sulfate. However, sulfate reduction rates did not correlate to exogenous dissolved organic carbon, implicating exogenous hydrogen or endogenous organic matter as the reductant (or even sulfur disproportionation). This research presents an opportunity to better understand the key variables that influence the rates of microbial sulfate reduction in hydrothermal environments and provides a framework for modeling sulfate reduction in mid-ocean ridge systems.

  20. Chemical Synthesis of Proteins

    PubMed Central

    Nilsson, Bradley L.; Soellner, Matthew B.; Raines, Ronald T.

    2010-01-01

    Proteins have become accessible targets for chemical synthesis. The basic strategy is to use native chemical ligation, Staudinger ligation, or other orthogonal chemical reactions to couple synthetic peptides. The ligation reactions are compatible with a variety of solvents and proceed in solution or on a solid support. Chemical synthesis enables a level of control on protein composition that greatly exceeds that attainable with ribosome-mediated biosynthesis. Accordingly, the chemical synthesis of proteins is providing previously unattainable insight into the structure and function of proteins. PMID:15869385

  1. Chemical Kinetic Modeling of Hydrogen Combustion Limits

    SciTech Connect

    Pitz, W J; Westbrook, C K

    2008-04-02

    A detailed chemical kinetic model is used to explore the flammability and detonability of hydrogen mixtures. In the case of flammability, a detailed chemical kinetic mechanism for hydrogen is coupled to the CHEMKIN Premix code to compute premixed, laminar flame speeds. The detailed chemical kinetic model reproduces flame speeds in the literature over a range of equivalence ratios, pressures and reactant temperatures. A series of calculation were performed to assess the key parameters determining the flammability of hydrogen mixtures. Increased reactant temperature was found to greatly increase the flame speed and the flammability of the mixture. The effect of added diluents was assessed. Addition of water and carbon dioxide were found to reduce the flame speed and thus the flammability of a hydrogen mixture approximately equally well and much more than the addition of nitrogen. The detailed chemical kinetic model was used to explore the detonability of hydrogen mixtures. A Zeldovich-von Neumann-Doring (ZND) detonation model coupled with detailed chemical kinetics was used to model the detonation. The effectiveness on different diluents was assessed in reducing the detonability of a hydrogen mixture. Carbon dioxide was found to be most effective in reducing the detonability followed by water and nitrogen. The chemical action of chemical inhibitors on reducing the flammability of hydrogen mixtures is discussed. Bromine and organophosphorus inhibitors act through catalytic cycles that recombine H and OH radicals in the flame. The reduction in H and OH radicals reduces chain branching in the flame through the H + O{sub 2} = OH + O chain branching reaction. The reduction in chain branching and radical production reduces the flame speed and thus the flammability of the hydrogen mixture.

  2. Desynchronization of stochastically synchronized chemical oscillators

    SciTech Connect

    Snari, Razan; Tinsley, Mark R. E-mail: kshowalt@wvu.edu; Faramarzi, Sadegh; Showalter, Kenneth E-mail: kshowalt@wvu.edu; Wilson, Dan; Moehlis, Jeff; Netoff, Theoden Ivan

    2015-12-15

    Experimental and theoretical studies are presented on the design of perturbations that enhance desynchronization in populations of oscillators that are synchronized by periodic entrainment. A phase reduction approach is used to determine optimal perturbation timing based upon experimentally measured phase response curves. The effectiveness of the perturbation waveforms is tested experimentally in populations of periodically and stochastically synchronized chemical oscillators. The relevance of the approach to therapeutic methods for disrupting phase coherence in groups of stochastically synchronized neuronal oscillators is discussed.

  3. Chemical and Physical Properties of Tantalum Powder

    NASA Astrophysics Data System (ADS)

    Purushotham, Y.; Balaji, T.; Kumar, Arbind; Govindaiah, R.; Sharma, M. K.; Sethi, V. C.; Prakash, T. L.

    The present work is intended to produce capacitor grade Tantalum powder by sodium reduction of potassium tantalum fluoride prepared from an indigenous ore source. The powder has been characterized for its chemical and physical properties, and compared with the commercially available powders. It is found that indigenous powder has higher impurity levels which could, however, be reduced to acceptance limits. The average particle size is within the prescribed limits.

  4. Reductive dechlorination of the nitrogen heterocyclic herbicide picloram

    SciTech Connect

    Ramanand, K.; Nagarajan, A.; Suflita, J.M. )

    1993-07-01

    Halogenated heterocyclic chemicals are widely used for manufacture of pesticides, pharmaceuticals, dyes, and explosives. Often they are environmentally mobile and can contaminate ground water reserves. Picloram, a broad spectrum herbicide, has a half life in the soil of as long as 1 year. This paper reports on the reductive dehalogenation of picloram in anoxic freshwater sediments, though not when sulfate or nitrate was available as a terminal electron acceptor, and its subsequent conversion to an unidentified product. 25 refs., 4 figs, 1 tab.

  5. Consumer's Guide to Radon Reduction

    MedlinePlus

    ... menu Learn the Issues Air Chemicals and Toxics Climate Change Emergencies Greener Living Health and Safety Land and Cleanup Pesticides Waste Water Science & Technology Air Climate Change Ecosystems Health Land, Waste and Cleanup Pesticides Substances ...

  6. Rapid reduction of titanium dioxide nano-particles by reduction with a calcium reductant

    NASA Astrophysics Data System (ADS)

    Kikuchi, Tatsuya; Yoshida, Masumi; Matsuura, Shiki; Natsui, Shungo; Tsuji, Etsuji; Habazaki, Hiroki; Suzuki, Ryosuke O.

    2014-09-01

    Micro-, submicron-, and nano-scale titanium dioxide particles were reduced by reduction with a metallic calcium reductant in calcium chloride molten salt at 1173 K, and the reduction mechanism of the oxides by the calcium reductant was explored. These oxide particles, metallic calcium as a reducing agent, and calcium chloride as a molten salt were placed in a titanium crucible and heated under an argon atmosphere. Titanium dioxide was reduced to metallic titanium through a calcium titanate and lower titanium oxide, and the materials were sintered together to form a micro-porous titanium structure in molten salt at high temperature. The reduction rate of titanium dioxide was observed to increase with decreasing particle size; accordingly, the residual oxygen content in the reduced titanium decreases. The obtained micro-porous titanium appeared dark gray in color because of its low surface reflection. Micro-porous metallic titanium with a low oxygen content (0.42 wt%) and a large surface area (1.794 m2 g-1) can be successfully obtained by reduction under optimal conditions.

  7. Reduced chemical warfare agent sorption in polyurethane-painted surfaces via plasma-enhanced chemical vapor deposition of perfluoroalkanes.

    PubMed

    Gordon, Wesley O; Peterson, Gregory W; Durke, Erin M

    2015-04-01

    Perfluoralkalation via plasma chemical vapor deposition has been used to improve hydrophobicity of surfaces. We have investigated this technique to improve the resistance of commercial polyurethane coatings to chemicals, such as chemical warfare agents. The reported results indicate the surface treatment minimizes the spread of agent droplets and the sorption of agent into the coating. The improvement in resistance is likely due to reduction of the coating's surface free energy via fluorine incorporation, but may also have contributing effects from surface morphology changes. The data indicates that plasma-based surface modifications may have utility in improving chemical resistance of commercial coatings.

  8. Revealing the Origin of Activity in Nitrogen-Doped Nanocarbons towards Electrocatalytic Reduction of Carbon Dioxide.

    PubMed

    Xu, Junyuan; Kan, Yuhe; Huang, Rui; Zhang, Bingsen; Wang, Bolun; Wu, Kuang-Hsu; Lin, Yangming; Sun, Xiaoyan; Li, Qingfeng; Centi, Gabriele; Su, Dangsheng

    2016-05-23

    Carbon nanotubes (CNTs) are functionalized with nitrogen atoms for reduction of carbon dioxide (CO2 ). The investigation explores the origin of the catalyst's activity and the role of nitrogen chemical states therein. The catalysts show excellent performances, with about 90 % current efficiency for CO formation and stability over 60 hours. The Tafel analyses and density functional theory calculations suggest that the reduction of CO2 proceeds through an initial rate-determining transfer of one electron to CO2 , which leads to the formation of carbon dioxide radical anion (CO2 (.-) ). The initial reduction barrier is too high on pristine CNTs, resulting in a very high overpotentials at which the hydrogen evolution reaction dominates over CO2 reduction. The doped nitrogen atoms stabilize the radical anion, thereby lowering the initial reduction barrier and improving the intrinsic activity. The most efficient nitrogen chemical state for this reaction is quaternary nitrogen, followed by pyridinic and pyrrolic nitrogen.

  9. Toxicity reduction in industrial effluents

    SciTech Connect

    Lankford, P.W.; Eckenfelder, W.W.

    1990-01-01

    The toxicity of manufacturing wastewaters to fish and other aquatic organisms is now being used by state and federal regulators to monitor and restrict industrial wastewater discharges. As a result, there is a great need for guidance on the subject of aquatic toxicity reduction in the field of industrial water pollution control. This book is a comprehensive reference source on the testing protocols, comparative data, and treatment techniques for effective toxicity reduction. Included in this book are detailed chapters covering various methods for toxicity reduction, such as the removal of metals, aerobic biological treatment, stripping of volatile organics, and management of sludges from toxic wastewater treatment. The book features: a complete overview of the subject, including background material for newcomers to the field; a basic summary and comparison of alternate treatment procedures; the latest methods for the identification of toxic components that readers can use for testing in their own laboratories; a description of applicable technologies for toxicity reduction; actual data from the use of processes that allow readers to compare technologies; solids management requirements including handling and disposal; useful economic comparisons of technologies; and illustrative case studies that demonstrate the application of the latest toxicity reduction technology and data to specific situations. Eleven chapters are processed separately in the appropriate data bases.

  10. Turbulent drag reduction over air- and liquid- impregnated surfaces

    NASA Astrophysics Data System (ADS)

    Rosenberg, Brian J.; Van Buren, Tyler; Fu, Matthew K.; Smits, Alexander J.

    2016-01-01

    Results on turbulent skin friction reduction over air- and liquid-impregnated surfaces are presented for aqueous Taylor-Couette flow. The surfaces are fabricated by mechanically texturing the inner cylinder and chemically modifying the features to make them either non-wetting with respect to water (air-infused, or superhydrophobic case), or wetting with respect to an oil that is immiscible with water (liquid-infused case). The drag reduction, which remains fairly constant over the Reynolds number range tested (100 ≤ Reτ ≤ 140), is approximately 10% for the superhydrophobic surface and 14% for the best liquid-infused surface. Our results suggest that liquid-infused surfaces may enable robust drag reduction in high Reynolds number turbulent flows without the shortcomings associated with conventional superhydrophobic surfaces, namely, failure under conditions of high hydrodynamic pressure and turbulent flow fluctuations.

  11. The Characterisation of the Products of Reduction of Chinkombe Ilmenite

    NASA Astrophysics Data System (ADS)

    Afewu, K. I.; Mwalula, J. B.; Kaoma, J.

    1998-12-01

    The characterisation of iron-containing species in Chinkombe ilmenite and its reduction products was undertaken using Mössbauer Spectroscopic techniques. The ore was reduced by graphite in an inert atmosphere. The effects of such variables as quantity of reductant, temperature and preoxidation were investigated. The ore was completely reduced to alpha-iron and titanium dioxide with 20% carbon for a period of one hour at 1373 K. Chemical mechanisms are proposed for the reduction and oxidation of Chinkombe ilmenite. In the processing of ilmenite to obtain synthetic rutile, the ultimate desire is to separate the Fe phase from the TiO2. Mössbauer Spectroscopy has unambiguously confirmed the desired transformation of the iron phase according to thermodynamic predictions. The information gained would be used to choose the conditions of the reduction process. The alpha-iron could be separated physically or chemically from the completely reduced product mass to obtain synthetic titanium dioxide suitable for the paint industry.

  12. Toxic Chemical System (TCS)

    SciTech Connect

    Del Gandio, P.

    1994-09-01

    The Toxic Chemical System (TCS) will have the capacity to process chemical data, calculate chemical formulas, and format the data into the United States (US) Environmental Protection Agency (EPA) Toxic Chemical Release Inventory Reporting Form R of Section 313 of the Emergency Planning and Community Right-to-Know Act (EPCRA), hereafter be referred to as ``Form R.`` The filing of this form is required of all industries which manufacture, process or otherwise use any EPA listed chemicals in quantities in excess of their threshold planning quantities (TPQ). Facilities required to file the Form R must report the quantities of both routine and accidental releases of listed toxic chemicals on-site during the calendar year and the amount contained in waste products transferred off-site. This paper describes a specialized computer system designed for regulatory compliance.

  13. Hand chemical burns.

    PubMed

    Robinson, Elliot P; Chhabra, A Bobby

    2015-03-01

    There is a vast and ever-expanding variety of potentially harmful chemicals in the military, industrial, and domestic landscape. Chemical burns make up a small proportion of all skin burns, yet they can cause substantial morbidity and mortality. Additionally, the hand and upper extremity are the most frequently involved parts of the body in chemical burns, and therefore these injuries may lead to severe temporary or permanent loss of function. Despite this fact, discussion of the care of these injuries is sparse in the hand surgery literature. Although most chemical burns require only first response and wound care, some require the attention of a specialist for surgical debridement and, occasionally, skin coverage and reconstruction. Exposure to certain chemicals carries the risk of substantial systemic toxicity and even mortality. Understanding the difference between thermal and chemical burns, as well as special considerations for specific compounds, will improve patient treatment outcomes.

  14. Chemical substitution in the undergraduate chemistry curriculum

    NASA Astrophysics Data System (ADS)

    Brook, Bryan David

    A recommended method for source reduction of pollutants is chemical substitution, in which hazardous materials are substituted for less hazardous materials. Here lab experiments and demonstrations were designed using household chemicals. The advantages include easy accessibility to low cost materials and minimal waste in comparison to traditional experiments. Students also showed more interest in performing experiments using familiar products. A Handbook of Household Chemicals was created. Using chemicals in the Handbook, qualitative and quantitative experiments are described that only require simple equipment. In addition, chemicals are identified in a quantitative analysis experiment with applications for upper level classes. Experiments requiring the use of water condensers were modified using an ice cooled condenser. The condenser, developed in our laboratory, is useful for distillation and reflux experiments where running water is not practical. Finally, demonstrations were designed for an overhead projector to be used in large classrooms. The experiments and demos can be used in any secondary school, college or university. The laboratory exercises can also accompany long distance learning and Internet chemistry courses. Several experiments using consumer products have been incorporated into the Pennsylvania Department of Education Science In Motion project. The program provides a van equipped with instruments and chemicals to be taken to local schools. Overall, the experiments discussed here provide a safe and low-cost alternative to traditional experiments.

  15. Model reduction by manifold boundaries

    NASA Astrophysics Data System (ADS)

    Transtrum, Mark

    2015-03-01

    Mathemtical models of physical systems can be interpreted as manifolds of predictions embedded in the space of data. For models of complex systems with many parameters, the corresponding model manifold is very high-dimensional but often very thin. This ``low effective dimensionality'' has been described as a hyper-ribbon and is characteristic of systems exhibiting simple, emergent behavior. I discuss a new model reduction method, the manifold boundary approximation method, which constructs a series of models by iteratively approximating the high-dimensional, thin manifold by its boundary. This model reduction method unifies many different model reduction techniques, such as renormalization group and continuum limits, while greatly expanding the domain of tractable models. I demonstrate with a model of a complex signaling network from systems biology. The method produces a series of approximations which reveal how microscopic parameters are systematically ``compressed'' into a few macroscopic degrees of freedom, effectively building a bridge between the microscopic and the macroscopic descriptions.

  16. The voice use reduction program.

    PubMed

    van der Merwe, Anita

    2004-08-01

    The purpose of this article is to describe a structured behavior modification approach to the reduction of voice use by clients with voice disorders. The Voice Use Reduction (VUR) Program is conceptualized as part of a comprehensive approach to the treatment of voice. The VUR Program provides guidelines for the classification of voice use situations, the assignment of voice use units to different situations, and the calculation of the maximum number of units per day and per week in a severe, moderate, and low voice use reduction program. Two case examples are described to illustrate the application of the VUR Program. The results of an evaluation of the VUR Program by 10 female students who presented with vocal nodules and applied the program also are included.

  17. Microbial reduction of iron ore

    DOEpatents

    Hoffmann, M.R.; Arnold, R.G.; Stephanopoulos, G.

    1989-11-14

    A process is provided for reducing iron ore by treatment with microorganisms which comprises forming an aqueous mixture of iron ore, microorganisms operable for reducing the ferric iron of the iron ore to ferrous iron, and a substrate operable as an energy source for the microbial reduction; and maintaining the aqueous mixture for a period of time and under conditions operable to effect the reduction of the ore. Preferably the microorganism is Pseudomonas sp. 200 and the reduction conducted anaerobically with a domestic wastewater as the substrate. An aqueous solution containing soluble ferrous iron can be separated from the reacted mixture, treated with a base to precipitate ferrous hydroxide which can then be recovered as a concentrated slurry. 11 figs.

  18. Microbial reduction of iron ore

    DOEpatents

    Hoffmann, Michael R.; Arnold, Robert G.; Stephanopoulos, Gregory

    1989-01-01

    A process is provided for reducing iron ore by treatment with microorganisms which comprises forming an aqueous mixture of iron ore, microorganisms operable for reducing the ferric iron of the iron ore to ferrous iron, and a substrate operable as an energy source for the microbial reduction; and maintaining the aqueous mixture for a period of time and under conditions operable to effect the reduction of the ore. Preferably the microorganism is Pseudomonas sp. 200 and the reduction conducted anaerobically with a domestic wastewater as the substrate. An aqueous solution containing soluble ferrous iron can be separated from the reacted mixture, treated with a base to precipitate ferrous hydroxide which can then be recovered as a concentrated slurry.

  19. Bacterial manganese reduction and growth with manganese oxide as the sole electron acceptor

    NASA Technical Reports Server (NTRS)

    Myers, Charles R.; Nealson, Kenneth H.

    1988-01-01

    Microbes that couple growth to the reduction of manganese could play an important role in the biogeochemistry of certain anaerobic environments. Such a bacterium, Alteromonas putrefaciens MR-1, couples its growth to the reduction of manganese oxides only under anaerobic conditions. The characteristics of this reduction are consistent with a biological, and not an indirect chemical, reduction of manganese, which suggest that this bacterium uses manganic oxide as a terminal electron acceptor. It can also utilize a large number of other compounds as terminal electron acceptors; this versatility could provide a distinct advantage in environments where electron-acceptor concentrations may vary.

  20. Advanced Chemical Propulsion for Science Missions

    NASA Technical Reports Server (NTRS)

    Liou, Larry

    2008-01-01

    The advanced chemical propulsion technology area of NASA's In-Space Technology Project is investing in systems and components for increased performance and reduced cost of chemical propulsion technologies applicable to near-term science missions. Presently the primary investment in the advanced chemical propulsion technology area is in the AMBR high temperature storable bipropellant rocket engine. Scheduled to be available for flight development starting in year 2008, AMBR engine shows a 60 kg payload gain in an analysis for the Titan-Enceladus orbiter mission and a 33 percent manufacturing cost reduction over its baseline, state-of-the-art counterpart. Other technologies invested include the reliable lightweight tanks for propellant and the precision propellant management and mixture ratio control. Both technologies show significant mission benefit, can be applied to any liquid propulsion system, and upon completion of the efforts described in this paper, are at least in parts ready for flight infusion. Details of the technologies are discussed.

  1. Excimer laser chemical problems

    SciTech Connect

    Tennant, R.; Peterson, N.

    1982-01-01

    Techniques need to be developed to maintain XeF and XeCl laser performance over long periods of time without degradation resulting from chemical processes occurring within the laser. The dominant chemical issues include optical damage, corrosions of laser materials, gas contamination, and control of halogen concentration. Each of these issues are discussed and summarized. The methods of minimizing or controlling the chemical processes involved are presented.

  2. Chemical penetration enhancers.

    PubMed

    Newton, Stephen J

    2013-01-01

    Chemical penetration enhancers are utilized in topical preparations as a method for enhancing permeation of drugs across the skin. In particular, they are utilized for transdermal delivery of medications in an attempt to produce a systemic response, to avoid first-pass metabolism, and to decrease the gastrointestinal transit time observed with oral medications. A review of the selection of chemical penetration enhancers, their mechanism of action, the most common chemical penetration enhancers in each class, and alternatives will be discussed in detail.

  3. Uranium isotopes fingerprint biotic reduction

    SciTech Connect

    Stylo, Malgorzata; Neubert, Nadja; Wang, Yuheng; Monga, Nikhil; Romaniello, Stephen J.; Weyer, Stefan; Bernier-Latmani, Rizlan

    2015-04-20

    Knowledge of paleo-redox conditions in the Earth’s history provides a window into events that shaped the evolution of life on our planet. The role of microbial activity in paleo-redox processes remains unexplored due to the inability to discriminate biotic from abiotic redox transformations in the rock record. The ability to deconvolute these two processes would provide a means to identify environmental niches in which microbial activity was prevalent at a specific time in paleo-history and to correlate specific biogeochemical events with the corresponding microbial metabolism. Here, we demonstrate that the isotopic signature associated with microbial reduction of hexavalent uranium (U), i.e., the accumulation of the heavy isotope in the U(IV) phase, is readily distinguishable from that generated by abiotic uranium reduction in laboratory experiments. Thus, isotope signatures preserved in the geologic record through the reductive precipitation of uranium may provide the sought-after tool to probe for biotic processes. Because uranium is a common element in the Earth’s crust and a wide variety of metabolic groups of microorganisms catalyze the biological reduction of U(VI), this tool is applicable to a multiplicity of geological epochs and terrestrial environments. The findings of this study indicate that biological activity contributed to the formation of many authigenic U deposits, including sandstone U deposits of various ages, as well as modern, Cretaceous, and Archean black shales. In addition, engineered bioremediation activities also exhibit a biotic signature, suggesting that, although multiple pathways may be involved in the reduction, direct enzymatic reduction contributes substantially to the immobilization of uranium.

  4. Uranium isotopes fingerprint biotic reduction

    DOE PAGES

    Stylo, Malgorzata; Neubert, Nadja; Wang, Yuheng; Monga, Nikhil; Romaniello, Stephen J.; Weyer, Stefan; Bernier-Latmani, Rizlan

    2015-04-20

    Knowledge of paleo-redox conditions in the Earth’s history provides a window into events that shaped the evolution of life on our planet. The role of microbial activity in paleo-redox processes remains unexplored due to the inability to discriminate biotic from abiotic redox transformations in the rock record. The ability to deconvolute these two processes would provide a means to identify environmental niches in which microbial activity was prevalent at a specific time in paleo-history and to correlate specific biogeochemical events with the corresponding microbial metabolism. Here, we demonstrate that the isotopic signature associated with microbial reduction of hexavalent uranium (U),more » i.e., the accumulation of the heavy isotope in the U(IV) phase, is readily distinguishable from that generated by abiotic uranium reduction in laboratory experiments. Thus, isotope signatures preserved in the geologic record through the reductive precipitation of uranium may provide the sought-after tool to probe for biotic processes. Because uranium is a common element in the Earth’s crust and a wide variety of metabolic groups of microorganisms catalyze the biological reduction of U(VI), this tool is applicable to a multiplicity of geological epochs and terrestrial environments. The findings of this study indicate that biological activity contributed to the formation of many authigenic U deposits, including sandstone U deposits of various ages, as well as modern, Cretaceous, and Archean black shales. In addition, engineered bioremediation activities also exhibit a biotic signature, suggesting that, although multiple pathways may be involved in the reduction, direct enzymatic reduction contributes substantially to the immobilization of uranium.« less

  5. Uranium isotopes fingerprint biotic reduction.

    PubMed

    Stylo, Malgorzata; Neubert, Nadja; Wang, Yuheng; Monga, Nikhil; Romaniello, Stephen J; Weyer, Stefan; Bernier-Latmani, Rizlan

    2015-05-01

    Knowledge of paleo-redox conditions in the Earth's history provides a window into events that shaped the evolution of life on our planet. The role of microbial activity in paleo-redox processes remains unexplored due to the inability to discriminate biotic from abiotic redox transformations in the rock record. The ability to deconvolute these two processes would provide a means to identify environmental niches in which microbial activity was prevalent at a specific time in paleo-history and to correlate specific biogeochemical events with the corresponding microbial metabolism. Here, we demonstrate that the isotopic signature associated with microbial reduction of hexavalent uranium (U), i.e., the accumulation of the heavy isotope in the U(IV) phase, is readily distinguishable from that generated by abiotic uranium reduction in laboratory experiments. Thus, isotope signatures preserved in the geologic record through the reductive precipitation of uranium may provide the sought-after tool to probe for biotic processes. Because uranium is a common element in the Earth's crust and a wide variety of metabolic groups of microorganisms catalyze the biological reduction of U(VI), this tool is applicable to a multiplicity of geological epochs and terrestrial environments. The findings of this study indicate that biological activity contributed to the formation of many authigenic U deposits, including sandstone U deposits of various ages, as well as modern, Cretaceous, and Archean black shales. Additionally, engineered bioremediation activities also exhibit a biotic signature, suggesting that, although multiple pathways may be involved in the reduction, direct enzymatic reduction contributes substantially to the immobilization of uranium.

  6. Uranium isotopes fingerprint biotic reduction

    PubMed Central

    Stylo, Malgorzata; Neubert, Nadja; Wang, Yuheng; Monga, Nikhil; Romaniello, Stephen J.; Weyer, Stefan; Bernier-Latmani, Rizlan

    2015-01-01

    Knowledge of paleo-redox conditions in the Earth’s history provides a window into events that shaped the evolution of life on our planet. The role of microbial activity in paleo-redox processes remains unexplored due to the inability to discriminate biotic from abiotic redox transformations in the rock record. The ability to deconvolute these two processes would provide a means to identify environmental niches in which microbial activity was prevalent at a specific time in paleo-history and to correlate specific biogeochemical events with the corresponding microbial metabolism. Here, we demonstrate that the isotopic signature associated with microbial reduction of hexavalent uranium (U), i.e., the accumulation of the heavy isotope in the U(IV) phase, is readily distinguishable from that generated by abiotic uranium reduction in laboratory experiments. Thus, isotope signatures preserved in the geologic record through the reductive precipitation of uranium may provide the sought-after tool to probe for biotic processes. Because uranium is a common element in the Earth’s crust and a wide variety of metabolic groups of microorganisms catalyze the biological reduction of U(VI), this tool is applicable to a multiplicity of geological epochs and terrestrial environments. The findings of this study indicate that biological activity contributed to the formation of many authigenic U deposits, including sandstone U deposits of various ages, as well as modern, Cretaceous, and Archean black shales. Additionally, engineered bioremediation activities also exhibit a biotic signature, suggesting that, although multiple pathways may be involved in the reduction, direct enzymatic reduction contributes substantially to the immobilization of uranium. PMID:25902522

  7. Approximate method for stochastic chemical kinetics with two-time scales by chemical Langevin equations.

    PubMed

    Wu, Fuke; Tian, Tianhai; Rawlings, James B; Yin, George

    2016-05-01

    The frequently used reduction technique is based on the chemical master equation for stochastic chemical kinetics with two-time scales, which yields the modified stochastic simulation algorithm (SSA). For the chemical reaction processes involving a large number of molecular species and reactions, the collection of slow reactions may still include a large number of molecular species and reactions. Consequently, the SSA is still computationally expensive. Because the chemical Langevin equations (CLEs) can effectively work for a large number of molecular species and reactions, this paper develops a reduction method based on the CLE by the stochastic averaging principle developed in the work of Khasminskii and Yin [SIAM J. Appl. Math. 56, 1766-1793 (1996); ibid. 56, 1794-1819 (1996)] to average out the fast-reacting variables. This reduction method leads to a limit averaging system, which is an approximation of the slow reactions. Because in the stochastic chemical kinetics, the CLE is seen as the approximation of the SSA, the limit averaging system can be treated as the approximation of the slow reactions. As an application, we examine the reduction of computation complexity for the gene regulatory networks with two-time scales driven by intrinsic noise. For linear and nonlinear protein production functions, the simulations show that the sample average (expectation) of the limit averaging system is close to that of the slow-reaction process based on the SSA. It demonstrates that the limit averaging system is an efficient approximation of the slow-reaction process in the sense of the weak convergence. PMID:27155630

  8. Approximate method for stochastic chemical kinetics with two-time scales by chemical Langevin equations.

    PubMed

    Wu, Fuke; Tian, Tianhai; Rawlings, James B; Yin, George

    2016-05-01

    The frequently used reduction technique is based on the chemical master equation for stochastic chemical kinetics with two-time scales, which yields the modified stochastic simulation algorithm (SSA). For the chemical reaction processes involving a large number of molecular species and reactions, the collection of slow reactions may still include a large number of molecular species and reactions. Consequently, the SSA is still computationally expensive. Because the chemical Langevin equations (CLEs) can effectively work for a large number of molecular species and reactions, this paper develops a reduction method based on the CLE by the stochastic averaging principle developed in the work of Khasminskii and Yin [SIAM J. Appl. Math. 56, 1766-1793 (1996); ibid. 56, 1794-1819 (1996)] to average out the fast-reacting variables. This reduction method leads to a limit averaging system, which is an approximation of the slow reactions. Because in the stochastic chemical kinetics, the CLE is seen as the approximation of the SSA, the limit averaging system can be treated as the approximation of the slow reactions. As an application, we examine the reduction of computation complexity for the gene regulatory networks with two-time scales driven by intrinsic noise. For linear and nonlinear protein production functions, the simulations show that the sample average (expectation) of the limit averaging system is close to that of the slow-reaction process based on the SSA. It demonstrates that the limit averaging system is an efficient approximation of the slow-reaction process in the sense of the weak convergence.

  9. Approximate method for stochastic chemical kinetics with two-time scales by chemical Langevin equations

    NASA Astrophysics Data System (ADS)

    Wu, Fuke; Tian, Tianhai; Rawlings, James B.; Yin, George

    2016-05-01

    The frequently used reduction technique is based on the chemical master equation for stochastic chemical kinetics with two-time scales, which yields the modified stochastic simulation algorithm (SSA). For the chemical reaction processes involving a large number of molecular species and reactions, the collection of slow reactions may still include a large number of molecular species and reactions. Consequently, the SSA is still computationally expensive. Because the chemical Langevin equations (CLEs) can effectively work for a large number of molecular species and reactions, this paper develops a reduction method based on the CLE by the stochastic averaging principle developed in the work of Khasminskii and Yin [SIAM J. Appl. Math. 56, 1766-1793 (1996); ibid. 56, 1794-1819 (1996)] to average out the fast-reacting variables. This reduction method leads to a limit averaging system, which is an approximation of the slow reactions. Because in the stochastic chemical kinetics, the CLE is seen as the approximation of the SSA, the limit averaging system can be treated as the approximation of the slow reactions. As an application, we examine the reduction of computation complexity for the gene regulatory networks with two-time scales driven by intrinsic noise. For linear and nonlinear protein production functions, the simulations show that the sample average (expectation) of the limit averaging system is close to that of the slow-reaction process based on the SSA. It demonstrates that the limit averaging system is an efficient approximation of the slow-reaction process in the sense of the weak convergence.

  10. The chemical biology of hydropersulfides (RSSH): Chemical stability, reactivity and redox roles.

    PubMed

    Saund, Simran S; Sosa, Victor; Henriquez, Stephanie; Nguyen, Q Nhu N; Bianco, Christopher L; Soeda, Shuhei; Millikin, Robert; White, Corey; Le, Henry; Ono, Katsuhiko; Tantillo, Dean J; Kumagai, Yoshito; Akaike, Takaaki; Lin, Joseph; Fukuto, Jon M

    2015-12-15

    Recent reports indicate the ubiquitous prevalence of hydropersulfides (RSSH) in mammalian systems. The biological utility of these and related species is currently a matter of significant speculation. The function, lifetime and fate of hydropersulfides will be assuredly based on their chemical properties and reactivity. Thus, to serve as the basis for further mechanistic studies regarding hydropersulfide biology, some of the basic chemical properties/reactivity of hydropersulfides was studied. The nucleophilicity, electrophilicity and redox properties of hydropersulfides were examined under biological conditions. These studies indicate that hydropersulfides can be nucleophilic or electrophilic, depending on the pH (i.e. the protonation state) and can act as good one- and two-electron reductants. These diverse chemical properties in a single species make hydropersulfides chemically distinct from other, well-known sulfur containing biological species, giving them unique and potentially important biological function.

  11. Closed reduction of a fractured bone

    MedlinePlus

    Fracture reduction - closed ... pain medicine you receive. There may be new fractures that occur with the reduction. If the reduction ... BD, Jupiter JBl, Krettek C, Anderson PA. Closed fracture management. In: Browner BD, Jupiter JB, Krettek C, ...

  12. Chemically Layered Porous Solids

    NASA Technical Reports Server (NTRS)

    Koontz, Steve

    1991-01-01

    Aerogels and other porous solids in which surfaces of pores have chemical properties varying with depth below macroscopic surfaces prepared by sequences of chemical treatments. Porous glass or silica bead treated to make two depth zones having different chemical properties. Beads dropped along tube filled with flowing gas containing atomic oxygen, generated in microwave discharge. General class of materials treatable include oxides of aluminum, silicon, zirconium, tin, titanium, and nickel, and mixtures of these oxides. Potential uses of treated materials include chromatographic separations, membrane separations, controlled releases of chemicals, and catalysis.

  13. Field emission chemical sensor

    DOEpatents

    Panitz, J.A.

    1983-11-22

    A field emission chemical sensor for specific detection of a chemical entity in a sample includes a closed chamber enclosing two field emission electrode sets, each field emission electrode set comprising (a) an electron emitter electrode from which field emission electrons can be emitted when an effective voltage is connected to the electrode set; and (b) a collector electrode which will capture said electrons emitted from said emitter electrode. One of the electrode sets is passive to the chemical entity and the other is active thereto and has an active emitter electrode which will bind the chemical entity when contacted therewith.

  14. Apparatus for chemical synthesis

    DOEpatents

    Kong, Peter C.; Herring, J. Stephen; Grandy, Jon D.

    2011-05-10

    A method and apparatus for forming a chemical hydride is described and which includes a pseudo-plasma-electrolysis reactor which is operable to receive a solution capable of forming a chemical hydride and which further includes a cathode and a movable anode, and wherein the anode is moved into and out of fluidic, ohmic electrical contact with the solution capable of forming a chemical hydride and which further, when energized produces an oxygen plasma which facilitates the formation of a chemical hydride in the solution.

  15. Chemical Processing Manual

    NASA Technical Reports Server (NTRS)

    Beyerle, F. J.

    1972-01-01

    Chemical processes presented in this document include cleaning, pickling, surface finishes, chemical milling, plating, dry film lubricants, and polishing. All types of chemical processes applicable to aluminum, for example, are to be found in the aluminum alloy section. There is a separate section for each category of metallic alloy plus a section for non-metals, such as plastics. The refractories, super-alloys and titanium, are prime candidates for the space shuttle, therefore, the chemical processes applicable to these alloys are contained in individual sections of this manual.

  16. 310 Facility chemical specifications

    SciTech Connect

    Hagerty, K.J.

    1997-05-21

    The 300 area Treated Effluent Disposal Facility (TEDF) was designed and built to treat the waste water from the 300 area process sewer system. Several treatment technologies are employed to remove the trace quantities of contaminants in the stream, including iron coprecipitation, clarification, filtration, ion exchange, and ultra violet light/hydrogen peroxide oxidation of organics. The chemicals that will be utilized in the treatment process are hydrogen peroxide, sulfuric acid, sodium hydroxide, and ferric chloride. This document annotates the required chemical characteristics of TEDF bulk chemicals as well as the criteria that were used to establish these criteria. The chemical specifications in appendix B are generated from this information.

  17. 2008 world direct reduction statistics

    SciTech Connect

    2009-07-01

    This supplement discusses total direct reduced iron (DRI) production for 2007 and 2008 by process. Total 2008 production by MIDREX(reg sign) direct reduction process plants was over 39.8 million tons. The total of all coal-based processes was 17.6 million tons. Statistics for world DRI production are also given by region for 2007 and 2008 and by year (1970-2009). Capacity utilization for 2008 by process is given. World DRI production by region and by process is given for 1998-2008 and world DRI shipments are given from the 1970s to 2008. A list of world direct reduction plants is included.

  18. EDRS: Electronography Data Reduction System

    NASA Astrophysics Data System (ADS)

    Warren-Smith, Rodney F.; Berry, David S.

    2015-12-01

    The Electronography Data Reduction System (EDRS) reduces and analyzes large format astronomical images and was written to be used from within ASPIC (ascl:1510.006). In its original form it specialized in the reduction of electronographic data but was built around a set of utility programs which were widely applicable to astronomical images from other sources. The programs align and calibrate images, handle lists of (X,Y) positions, apply linear geometrical transformations and do some stellar photometry. This package is now obsolete.

  19. Regioselective electrochemical reduction of 2,4-dichlorobiphenyl - Distinct standard reduction potentials for carbon-chlorine bonds using convolution potential sweep voltammetry

    NASA Astrophysics Data System (ADS)

    Muthukrishnan, A.; Sangaranarayanan, M. V.; Boyarskiy, V. P.; Boyarskaya, I. A.

    2010-04-01

    The reductive cleavage of carbon-chlorine bonds in 2,4-dichlorobiphenyl (PCB-7) is investigated using the convolution potential sweep voltammetry and quantum chemical calculations. The potential dependence of the logarithmic rate constant is non-linear which indicates the validity of Marcus-Hush theory of quadratic activation-driving force relationship. The ortho-chlorine of the 2,4-dichlorobiphenyl gets reduced first as inferred from the quantum chemical calculations and bulk electrolysis. The standard reduction potentials pertaining to the ortho-chlorine of 2,4-dichlorobiphenyl and that corresponding to para chlorine of the 4-chlorobiphenyl have been estimated.

  20. Application of a New Selective Noncatalytic NO Reduction System to Diesel Exhaust

    NASA Astrophysics Data System (ADS)

    Nakanishi, Yasufumi; Gong, Joon Dugk; Yoshihara, Yoshinobu; Nishiwaki, Kazuie

    The chemical gas-phase reduction process used to reduce nitric oxide (NO) in diesel engine exhaust has been applied to a high-speed, light-duty diesel engine. The chemical gas-phase reduction process involves adding methylamine (CH3NH2) in water solution to the exhaust gas as an NO reduction agent. In this study, an experimental selective noncatalytic NO reduction system designed to be used with a diesel engine was applied to evaluate this technique for practical use. The NOx reduction ratio (RNOx) of methylamine processes with and without the installation of a particulate filter was investigated. Two different mixing chambers with different volumes and residence times (0.1s and 0.17s) were also tested. Longer residence times were required to achieve a given level of NOx reduction in unfiltered exhaust, suggesting that the presence of particulate matter inhibits NO reduction. For the standard residence time (0.1s), the process achieved 64% NO reduction in unfiltered diesel exhaust, which increased to 80% NO reduction when a particle filter was fitted to the system.

  1. Background Reduction in Cryogenic Detectors

    SciTech Connect

    Bauer, Daniel A.

    2005-09-08

    This paper discusses the background reduction and rejection strategy of the Cryogenic Dark Matter Search (CDMS) experiment. Recent measurements of background levels from CDMS II at Soudan are presented, along with estimates for future improvements in sensitivity expected for a proposed SuperCDMS experiment at SNOLAB.

  2. Poverty Reduction Begins with Children.

    ERIC Educational Resources Information Center

    United Nations Children's Fund, New York, NY.

    This report describes how children bear the brunt of poverty and explains why they are central to poverty reduction in developing nations. The report also illustrates UNICEF's support for the process of improving access to, and quality of, health care, education, water and sanitation, and child protection. It describes how the participation of the…

  3. Background reduction in cryogenic detectors

    SciTech Connect

    Bauer, Daniel A.; /Fermilab

    2005-04-01

    This paper discusses the background reduction and rejection strategy of the Cryogenic Dark Matter Search (CDMS) experiment. Recent measurements of background levels from CDMS II at Soudan are presented, along with estimates for future improvements in sensitivity expected for a proposed SuperCDMS experiment at SNOLAB.

  4. Gaseous reduction of laterite ores

    NASA Astrophysics Data System (ADS)

    Utigard, T.; Bergman, R. A.

    1993-04-01

    Lateritic nickel ores have been reduced under laboratory conditions. The reduction experiments were carried out at temperatures from 500 °C to 1100 °C in a horizontal tube furnace using various mixtures of H2 and CO2. The hydrogen evolution method was used to measure the degree of metallization of the reduced ore. It was found that the rate of reduction was very low at 500 °C but then increased rapidly upon heating the ore to 600 °C. The percent metallics increased with increasing H2 to CO2 ratios in the reducing gas. At temperatures between 600 °C and 1100 °C, a H2 to CO2 ratio of 3 leads to the formation of 5 to 6 pct metallics in the reduced calcine was shown. Heating the ore in air or nitrogen prior to reduction does not affect the degree of metallization. A H2 to CO2 ratio of at least 4 is required to obtain a ferronickel product analyzing 36 pct nickel if no further reduction is carried out during the subsequent smelting operation.

  5. Workforce Reductions. An Annotated Bibliography.

    ERIC Educational Resources Information Center

    Hickok, Thomas A.; Hickok, Thomas A.

    This report, which is based on a review of practitioner-oriented sources and scholarly journals, uses a three-part framework to organize annotated bibliographies that, together, list a total of 104 sources that provide the following three perspectives on work force reduction issues: organizational, organizational-individual relationship, and…

  6. Dimensional Reduction and Hadronic Processes

    SciTech Connect

    Signer, Adrian; Stoeckinger, Dominik

    2008-11-23

    We consider the application of regularization by dimensional reduction to NLO corrections of hadronic processes. The general collinear singularity structure is discussed, the origin of the regularization-scheme dependence is identified and transition rules to other regularization schemes are derived.

  7. Palladium Catalyzed Reduction of Nitrobenzene.

    ERIC Educational Resources Information Center

    Mangravite, John A.

    1983-01-01

    Compares two palladium (Pd/C) reducing systems to iron/tin-hydrochloric acid (Fe/HCl and Sn/HCl) reductions and suggests an efficient, clean, and inexpensive procedures for the conversion of nitrobenzene to aniline. Includes laboratory procedures used and discussion of typical results obtained. (JN)

  8. APPLICATION OF RADON REDUCTION METHODS

    EPA Science Inventory

    The document is intended to aid homeowners and contractors in diagnosing and solving indoor radon problems. It will also be useful to State and Federal regulatory officials and many other persons who provide advice on the selection, design and operation of radon reduction methods...

  9. Students Enjoy Chemical Sensation

    ERIC Educational Resources Information Center

    Barry, Dana M.; Kanematsu, Hideyuki

    2003-01-01

    This exciting new way of teaching high school/college chemistry combines music, visual aids, and chemical experiments in multi-sensory lessons that motivate students and provide them with meaningful learning experiences in science. The method, known as the Chemical Sensation Project, acknowledges that some individuals learn by seeing or hearing,…

  10. Chemical Process Synthesis.

    ERIC Educational Resources Information Center

    Siirola, J. J.

    1982-01-01

    Process synthesis is the specification of chemical and physical operations and the selection and interconnection of equipment to implement these operations to effect desired chemical processing transformations. Optimization and evolutionary and systematic generation process synthesis approaches are described. (Author/SK)

  11. Fundamentals of Chemical Processes.

    ERIC Educational Resources Information Center

    Moser, William R.

    1985-01-01

    Describes a course that provides students with a fundamental understanding of the chemical, catalytic, and engineering sciences related to the chemical reactions taking place in a variety of reactors of different configurations. Also describes the eight major lecture topics, course examinations, and term papers. The course schedule is included.…

  12. Chemical Reaction Problem Solving.

    ERIC Educational Resources Information Center

    Veal, William

    1999-01-01

    Discusses the role of chemical-equation problem solving in helping students predict reaction products. Methods for helping students learn this process must be taught to students and future teachers by using pedagogical skills within the content of chemistry. Emphasizes that solving chemical reactions should involve creative cognition where…

  13. Chemical Equation Balancing.

    ERIC Educational Resources Information Center

    Blakley, G. R.

    1982-01-01

    Reviews mathematical techniques for solving systems of homogeneous linear equations and demonstrates that the algebraic method of balancing chemical equations is a matter of solving a system of homogeneous linear equations. FORTRAN programs using this matrix method to chemical equation balancing are available from the author. (JN)

  14. Elemental Chemical Puzzlers

    ERIC Educational Resources Information Center

    Thomas, Nicholas C.

    2009-01-01

    This paper provides nine short chemically based puzzles or problems extensible for use with students from middle school to college. Some of these will strengthen students' recognition of individual elements and element names. Others require students to focus on the salient properties of given chemical elements.

  15. Difficult Decisions: Chemical Warfare.

    ERIC Educational Resources Information Center

    Slesnick, Irwin L.; Miller, John A.

    1988-01-01

    Gives the background history and chemistry of modern day chemical warfare from World War I to the present. Provides discussion questions to stimulate deeper thinking on the issue. Contains a discussion activity called "Can New Chemical Weapons Lead to Humane Warfare?" (CW)

  16. Chemicals in Everyday Life.

    ERIC Educational Resources Information Center

    Seymour, Raymond B.

    1987-01-01

    Discusses the dependencies of people on chemicals in various aspects of life. Describes some of the natural and synthetic chemicals currently used in food production, clothing, shelter, travel and exploration, sports and recreation, ventilation, heating and cooling, communications, decoration, sanitation, and education. (TW)

  17. Great Lakes: Chemical Monitoring

    ERIC Educational Resources Information Center

    Delfino, Joseph J.

    1976-01-01

    The Tenth Great Lakes Regional Meeting of the American Chemical Society met to assess current Chemical Research activity in the Great Lakes Basin, and addressed to the various aspects of the theme, Chemistry of the Great Lakes. Research areas reviewed included watershed studies, atmospheric and aquatic studies, and sediment studies. (BT)

  18. Chemicals and Allied Products.

    ERIC Educational Resources Information Center

    Nelson, R. F.; Hovious, J. C.

    1978-01-01

    Presents a literature review of wastes from chemical industry, covering publications of 1976-77. This review covers: (1) wastewater treatment by-product type; (2) biological, and physical/chemical treatments; and (3) source treatment. A list of 80 references is also presented. (HM)

  19. Microorganisms and Chemical Pollution

    ERIC Educational Resources Information Center

    Alexander, M.

    1973-01-01

    Discusses the importance of microorganisms in chemical pollution and pollution abatement. Selected chemical pollutants are chosen to illustrate that microorganisms synthesize hazardous substances from reasonably innocuous precursors, while others act as excellent environmental decontaminating agents by removing undesirable natural and synthetic…

  20. Chemical Compositions of Stars

    NASA Astrophysics Data System (ADS)

    Leckrone, D.; Murdin, P.

    2000-11-01

    In 1835, in a famously inaccurate forecast, the French philosopher Auguste Comte wrote of stars that, `We understand the possibility of determining their shapes, their distances, their sizes and their movements; whereas we would never know how to study by any means their chemical composition…'. At the close of the 20th century the accurate measurement of the abundances of the chemical elements in...