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Sample records for chemical mixtures international

  1. Toxicology of chemical mixtures: International perspective

    NARCIS (Netherlands)

    Feron, V.J.; Cassee, F.R.; Groten, J.P.

    1998-01-01

    This paper reviews major activities outside the United States on human health issues related to chemical mixtures. In Europe an international study group on combination effects has been formed and has started by defining synergism and antagonism. Successful research programs in Europe include the de

  2. International issues on human health effects of exposure to chemical mixtures.

    Science.gov (United States)

    Feron, Victor J; Cassee, Flemming R; Groten, John P; van Vliet, Petronella W; van Zorge, Job A

    2002-12-01

    In this article, we highlight new developments and recent studies concerning adverse human health effects related to chemical mixtures. One group of activities comprises the development of a new computer program for analyzing mixture studies and a mathematical model as a basis for combination rules that predict the toxicity of mixtures. Other new activities in the area of experimental studies are the application of gene expression technologies in mixture research, and pattern recognition as a tool in safety evaluation of complex mixtures. A "bottom-up" approach for chemosensory detection of mixtures has recently been presented. Other topics include a method for the safety evaluation of natural flavoring complexes, and an evaluation of the possible health effects of the simultaneous intake of food additives. Examples of issues related to mixtures of airborne chemicals are potential interaction of fine particles and gaseous pollutants in ambient air, nasal cancer associated with inhaled chemical mixtures, and the recommendation of a limit value for volatile organic compounds. Topics of a more strategic nature include studies concerning the public health effects of large airports, and the development of criteria for a harmonized classification of chemical mixtures. This overview illustrates that strategies to tackle the safety evaluation of combined exposures and complex mixtures as well as models facilitating the interpretation of findings in the context of risk assessment of mixtures have become increasingly important. It is true that exposure of humans to chemical mixtures is the rule rather than the exception, and therefore health risk assessments should focus on mixtures and not on single chemicals. It is also true, however, that humans have learned to cope with exposure to huge numbers of chemicals simultaneously (food, water, air, soil, and consumer products). Therefore, in view of limited resources for toxicological research, the focus in toxicology should be

  3. Toxicological evaluation of chemical mixtures

    NARCIS (Netherlands)

    Feron, V.J.; Groten, J.P.

    2002-01-01

    This paper addresses major developments in the safety evaluation of chemical mixtures during the past 15 years, reviews today's state of the art of mixture toxicology, and discusses challenges ahead. Well-thought-out tailor-made mechanistic and empirical designs for studying the toxicity of mixtures

  4. Flows and chemical reactions in homogeneous mixtures

    CERN Document Server

    Prud'homme, Roger

    2013-01-01

    Flows with chemical reactions can occur in various fields such as combustion, process engineering, aeronautics, the atmospheric environment and aquatics. The examples of application chosen in this book mainly concern homogeneous reactive mixtures that can occur in propellers within the fields of process engineering and combustion: - propagation of sound and monodimensional flows in nozzles, which may include disequilibria of the internal modes of the energy of molecules; - ideal chemical reactors, stabilization of their steady operation points in the homogeneous case of a perfect mixture and c

  5. Continuum thermodynamics of chemically reacting fluid mixtures

    CERN Document Server

    Bothe, Dieter

    2014-01-01

    We consider viscous and heat conducting mixtures of molecularly miscible chemical species forming a fluid in which the constituents can undergo chemical reactions. Assuming a common temperature for all components, a first main aim is the derivation of a closed system of partial mass and partial momentum balances plus a common balance of internal energy. This is achieved by careful exploitation of the entropy principle which, in particular, requires appropriate definitions of absolute temperature and chemical potentials based on an adequate definition of thermal energy that excludes diffusive contributions. The latter is crucial in order to obtain a closure framework for the interaction forces between the different species. The interaction forces split into a thermo-mechanical and a chemical part, where the former turns out to be symmetric if binary interactions are assumed. In the non-reactive case, this leads to a system of Navier-Stokes type sub-systems, coupled by interspecies friction forces. For chemical...

  6. Existing chemicals: international activities.

    Science.gov (United States)

    Purchase, J F

    1989-01-01

    The standards of care used in the protection of the health and safety of people exposed to chemicals has increased dramatically in the last decade. Standards imposed by regulation and those adopted by industry have required a greater level of knowledge about the hazards of chemicals. In the E.E.C., the 6th amendment of the dangerous substances directive imposed the requirement that al new chemicals should be tested according to prescribed programme before introduction on to the market. The development of a European inventory of existing chemicals was an integral part of the 6th amendment. It has now become clear that increased standards of care referred to above must be applied to the chemicals on the inventory list. There is, however, a considerable amount of activity already under way in various international agencies. The OECD Chemicals Programme has been involved in considering the problem of existing chemicals for some time, and is producing a priority list and action programme. The International Programme on Chemical Safety produces international chemical safety cards, health and safety guides and environmental health criteria documents. The international register of potentially toxic compounds (part of UNEP) has prepared chemical data profiles on 990 compounds. The International Agency for Research on Cancer prepared monographs on the carcinogenic risk of chemicals to man. So far 42 volumes have been prepared covering about 900 substances. IARC and IPCS also prepare periodic reports on ongoing research on carcinogenicity or toxicity (respectively) of chemicals. The chemical industry through ECETOC (the European Chemical Industry Ecology and Toxicology Centre) has mounted a major initiative on existing chemicals. Comprehensive reviews of the toxicity of selected chemicals are published (Joint Assessment of Commodity Chemicals). In its technical report no. 30 ECETOC lists reviews and evaluations by major national and international organisations, which provides

  7. Mixture toxicity of PBT-like chemicals

    DEFF Research Database (Denmark)

    Syberg, Kristian; Dai, Lina; Ramskov, Tina;

    beyond that of the individual components. Firstly, the effects of three chemicals with PBT-like properties (acetyl cedrene, pyrene and triclosan) was examined on the freshwater snail, Potamopyrgus antipodarum. Secondly, mixture bioaccumulation of the same three chemicals were assessed experimentally...

  8. Chemical mixtures: considering the evolution of toxicology and chemical assessment.

    Science.gov (United States)

    Monosson, Emily

    2005-04-01

    The assessment of chemical mixtures is a complex topic for toxicologists, regulators, and the public. In this article the linkage between the science of toxicology and the needs of governmental regulatory agencies in the United States is explored through an overview of environmental regulations enacted over the past century and a brief history of modern toxicology. One of the goals of this overview is to encourage both regulators and scientists to consider the benefits and limitations of this science-regulatory relationship as they tackle existing issues such as chemical mixtures. It is clear that a) over the past 100 years chemical regulation and toxicologic research, have in large part, shared a common emphasis on characterization and regulation of individual chemicals. But chemical mixtures have been, and continue to be, evaluated at hazardous waste sites around the United States. For this reason the current U.S. Environmental Protection Agency guidelines for chemical mixtures assessment are also reviewed. These guidelines highlight the current practice of mixtures assessment, which relies primarily on the existing single-chemical database. It is also clear that b) the science and assessment of chemical mixtures are moving forward through the combined efforts of regulatory agencies and scientists from a broad range of disciplines, including toxicology. Because toxicology is at this exciting crossroads, particular attention should be paid to the forces (e.g., public demands, regulatory needs, funding, academic interests) that both promote and limit the growth of this expanding discipline.

  9. Flows and chemical reactions in heterogeneous mixtures

    CERN Document Server

    Prud'homme, Roger

    2014-01-01

    This book - a sequel of previous publications 'Flows and Chemical Reactions' and 'Chemical Reactions in Flows and Homogeneous Mixtures' - is devoted to flows with chemical reactions in heterogeneous environments.  Heterogeneous media in this volume include interfaces and lines. They may be the site of radiation. Each type of flow is the subject of a chapter in this volume. We consider first, in Chapter 1, the question of the generation of environments biphasic individuals: dusty gas, mist, bubble flow.  Chapter 2 is devoted to the study at the mesoscopic scale: particle-fluid exchange of mom

  10. Quasi-chemical approximation for polyatomic mixtures

    CERN Document Server

    Dávila, M V; Matoz-Fernandez, D A; Ramirez-Pastor, A J

    2016-01-01

    The statistical thermodynamics of binary mixtures of polyatomic species was developed on a generalization in the spirit of the lattice-gas model and the quasi-chemical approximation (QCA). The new theoretical framework is obtained by combining: (i) the exact analytical expression for the partition function of non-interacting mixtures of linear $k$-mers and $l$-mers (species occupying $k$ sites and $l$ sites, respectively) adsorbed in one dimension, and its extension to higher dimensions; and (ii) a generalization of the classical QCA for multicomponent adsorbates and multisite-occupancy adsorption. The process is analyzed through the partial adsorption isotherms corresponding to both species of the mixture. Comparisons with analytical data from Bragg-Williams approximation (BWA) and Monte Carlo simulations are performed in order to test the validity of the theoretical model. Even though a good fitting is obtained from BWA, it is found that QCA provides a more accurate description of the phenomenon of adsorpti...

  11. Spinodal decomposition of chemically reactive binary mixtures

    Science.gov (United States)

    Lamorgese, A.; Mauri, R.

    2016-08-01

    We simulate the influence of a reversible isomerization reaction on the phase segregation process occurring after spinodal decomposition of a deeply quenched regular binary mixture, restricting attention to systems wherein material transport occurs solely by diffusion. Our theoretical approach follows a diffuse-interface model of partially miscible binary mixtures wherein the coupling between reaction and diffusion is addressed within the frame of nonequilibrium thermodynamics, leading to a linear dependence of the reaction rate on the chemical affinity. Ultimately, the rate for an elementary reaction depends on the local part of the chemical potential difference since reaction is an inherently local phenomenon. Based on two-dimensional simulation results, we express the competition between segregation and reaction as a function of the Damköhler number. For a phase-separating mixture with components having different physical properties, a skewed phase diagram leads, at large times, to a system converging to a single-phase equilibrium state, corresponding to the absolute minimum of the Gibbs free energy. This conclusion continues to hold for the critical phase separation of an ideally perfectly symmetric binary mixture, where the choice of final equilibrium state at large times depends on the initial mean concentration being slightly larger or less than the critical concentration.

  12. Chemometrics as a tool to analyse complex chemical mixtures

    DEFF Research Database (Denmark)

    Christensen, J. H.

    Chemical characterisation of contaminant mixtures is important for environmental forensics and risk assessment. The great challenge in future research lies in develop- ing suitable, rapid, reliable and objective methods for analysis of the composition of complex chemical mixtures. This thesis...

  13. 21 CFR 1310.12 - Exempt chemical mixtures.

    Science.gov (United States)

    2010-04-01

    ... § 1310.13 affects the criminal liability for illegal possession, distribution, exportation, or importation of listed chemicals contained in the exempt chemical mixture or the civil liability for...

  14. Health and environmental effects of complex chemical mixtures: proceedings

    Energy Technology Data Exchange (ETDEWEB)

    1985-01-01

    The Office of Health and Environmental Research (OHER) of the Department of Energy supports a broad long-term research program on human health and environmental effects from potential exposure to energy-related complex chemical mixtures. The program seeks basic mechanistic data on the effects of complex mixtures at the cellular, molecular, and whole animal levels to aid in predicting human health effects and seeks ecological data on biological and physical transformations in the mixtures, concentrations of the mixtures in various compartments of the environment, and potential routes for human exposure to these mixtures (e.g., food chain). On June 17-18, 1985, OHER held its First Annual Technical Meeting on the Complex Chemical Mixtures Program in Chicago, IL. The primary purpose of the meeting was to enable principal investigators to report the research status and accomplishments of ongoing complex chemical mixture studies supported by OHER. To help focus future research directions round table discussions were conducted.

  15. Safety evaluation of chemical mixtures and combinations of chemical and non-chemical stressors

    NARCIS (Netherlands)

    Jonker, D.; Freidig, A.P.; Groten, J.P.; Hollander, A.E.M.de; Stierum, R.H.; Woutersen, R.A.; Feron, V.J.

    2004-01-01

    Recent developments in hazard identification and risk assessment of chemical mixtures are reviewed. Empirical, descriptive approaches to study and characterize the toxicity of mixtures have dominated during the past two decades, but an increasing number of mechanistic approaches have made their entr

  16. 21 CFR 1310.13 - Exemption of chemical mixtures; application.

    Science.gov (United States)

    2010-04-01

    ...-listed chemicals); or (ii) If a group of mixtures, the concentration range for the listed chemical and a listing of all non-listed chemicals with respective concentration ranges. (5) (i) The chemical and... file written comments on or objections to the order. If any comments or objections raise...

  17. Tools and perspectives for assessing chemical mixtures and multiple stressors

    DEFF Research Database (Denmark)

    Løkke, Hans; Ragas, Ad M. J.; Holmstrup, Martin

    2013-01-01

    The present paper summarizes the most important insights and findings of the EU NoMiracle project with a focus on (1) risk assessment of chemical mixtures, (2) combinations of chemical and natural stressors, and (3) the receptor-oriented approach in cumulative risk assessment. The project aimed a...... is suggested. The results are discussed in the light of recent developments in risk assessment of mixtures and multiple stressors....

  18. Thyroid disrupting chemicals: Mechanisms and mixtures

    Science.gov (United States)

    Environmental contaminants are known to act as thyroid disrupting chemicals (TDCs). Broadly defined, TDCs are xenobiotics that alter the structure or function of the thyroid gland, alter regulatory enzymes associated with thyroid hormone (TH) homeostasis, or change circulating o...

  19. Threshold of Toxicological Concern (TTC) and Mixture Effects of Chemicals

    OpenAIRE

    Wennermark, Henrik

    2014-01-01

    The threshold of toxicological concern (TTC) has been proposed as a novel tool in the risk assessment of chemicals, which based on knowledge of chemical structure, can set safe-levels without the necessity of performing expensive and time consuming animal toxicity experiments. However, questions have been raised whether the TTC approach, in a sufficient manner, are capable of setting safe thresholds in the context of chemicals mixture effects. This is the subject for this project. The current...

  20. Mixtures of Estrogenic Chemicals Enhance Vitellogenic Response in Sea Bass

    OpenAIRE

    Correia, AD; Freitas, S.; Scholze, M; Gonçalves, J; Booij, P.; Lamoree, MH; Mañanós, E; Reis-Henriques, MA

    2007-01-01

    BACKGROUND: The potential impact of natural and synthetic estrogens on aquatic ecosystems has attracted considerable attention because it is currently accepted that their joint effects are more severe when they are present in mixtures. Although it is well-known that they occur as mixtures in the marine environment, there is little information about the combined effects of estrogenic chemicals on marine biota. OBJECTIVE: In 14-day tests with juvenile sea bass, we analyzed singly and in combina...

  1. Effect of Gas Mixture Composition on the Parameters of an Internal Combustion Engine

    Directory of Open Access Journals (Sweden)

    Andrej Chríbik

    2012-01-01

    Full Text Available This paper deals with the use of the internal combustion piston engine, which is a drive unit for micro-cogeneration units. The introduction is a brief statement of the nature of gas mixture compositions that are useful for the purposes of combustion engines, together with the basic physical and chemical properties relevant to the burning of this gas mixture. Specifically, we will discuss low-energy gases (syngases and mixtures of natural gas with hydrogen. The second section describes the conversion of the Lombardini LGW 702 combustion engine that is necessary for these types of combustion gases. Before the experimental measurements, a simulation in the Lotus Engine simulation program was carried out to make a preliminary assessment of the impact on the performance of an internal combustion engine. The last section of the paper presents the experimental results of partial measurements of the performance and emission parameters of an internal combustion engine powered by alternative fuels.

  2. Statistically designed experiments to screen chemical mixtures for possible interactions

    NARCIS (Netherlands)

    Groten, J.P.; Tajima, O.; Feron, V.J.; Schoen, E.D.

    1998-01-01

    For the accurate analysis of possible interactive effects of chemicals in a defined mixture, statistical designs are necessary to develop clear and manageable experiments. For instance, factorial designs have been successfully used to detect two-factor interactions. Particularly useful for this purp

  3. Towards decomposition of live chemical agents by pyrotechnic mixtures

    NARCIS (Netherlands)

    Bouma, R.H.B.; Noort, D.

    2012-01-01

    The aim of this study is to contribute to improved EOD neutralisation techniques against improvised explosive devices (IEDs) containing chemical agents. The decomposition of dimethyl methylphosphonate (DMMP) when exposed to a burning aluminum/potassium nitrate pyrotechnic mixture is studied experime

  4. Optimization of Internal Thermally Coupled Distillation Columns of Nonideal Mixture

    Institute of Scientific and Technical Information of China (English)

    刘兴高; 徐用懋; 钱积新

    2001-01-01

    Internal thermally coupled distillation column(ITCDIC) is a frontier in energy saving distillation research. In this paper, the optimal assessment on the energy saving and the operating cost for ITCDIC of nonideal mixture is explored. An evaluating method is proposed, and the pertinent optimization model is then derived. The ethanol-water system is studied as an illustrative example. The optimization results show that the maximum energy saving in ITCDIC process is about 35% and the maximum operating cost saving in ITCDIC process is about 30%,as compared with a conventional distillation column(CDIC) under the minimum reflux ratio operating; the optimal operating pressure of the rectifying section is found to be around 0.25 MPa; the effects of the feed composition,operating pressure and the heat transfer rate on operation are also found and analyzed. It is revealed that ITCDIC process possesses high energy saving potential and promising economical prospect.

  5. Thermodynamic Analysis of Chemically Reacting Mixtures and Their Kinetics: Example of a Mixture of Three Isomers.

    Science.gov (United States)

    Pekař, Miloslav

    2016-10-18

    Thermodynamics provides consequences of and restrictions on chemically reacting mixtures, particularly their kinetics, which have not been fully explored. Herein, a comprehensive thermodynamic analysis is illustrated for a reacting mixture of three isomers. The rate equation is first derived on the basis of the results of nonequilibrium continuum thermodynamics of linear fluids, and is then subjected to the requirement of consistency with entropic inequality (the second law). This consistency test involves the correct representation of the reaction rate as a function of affinities. It is shown that entropic inequality restricts the signs or values of coefficients in the constitutive equations for reaction rates/rate constants. The use of reverse rate constants and the identification of thermodynamic and kinetic equilibrium constants are not necessary in this approach. Although the presented thermodynamic analysis works only for independent reactions, the rates of dependent reactions are not excluded from having effects on kinetics. It is shown that the rates of dependent reactions are combined from the rates of independent reactions differently than dependent reactions are combined from independent reactions. The results are compared to the classical mass-action rate equations, and new restrictions on the values of the classical rate constants are derived.

  6. General multi-group macroscopic modeling for thermo-chemical non-equilibrium gas mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yen, E-mail: yen.liu@nasa.gov; Vinokur, Marcel [NASA Ames Research Center, Moffett Field, California 94035 (United States); Panesi, Marco; Sahai, Amal [University of Illinois, Urbana-Champaign, Illinois 61801 (United States)

    2015-04-07

    This paper opens a new door to macroscopic modeling for thermal and chemical non-equilibrium. In a game-changing approach, we discard conventional theories and practices stemming from the separation of internal energy modes and the Landau-Teller relaxation equation. Instead, we solve the fundamental microscopic equations in their moment forms but seek only optimum representations for the microscopic state distribution function that provides converged and time accurate solutions for certain macroscopic quantities at all times. The modeling makes no ad hoc assumptions or simplifications at the microscopic level and includes all possible collisional and radiative processes; it therefore retains all non-equilibrium fluid physics. We formulate the thermal and chemical non-equilibrium macroscopic equations and rate coefficients in a coupled and unified fashion for gases undergoing completely general transitions. All collisional partners can have internal structures and can change their internal energy states after transitions. The model is based on the reconstruction of the state distribution function. The internal energy space is subdivided into multiple groups in order to better describe non-equilibrium state distributions. The logarithm of the distribution function in each group is expressed as a power series in internal energy based on the maximum entropy principle. The method of weighted residuals is applied to the microscopic equations to obtain macroscopic moment equations and rate coefficients succinctly to any order. The model’s accuracy depends only on the assumed expression of the state distribution function and the number of groups used and can be self-checked for accuracy and convergence. We show that the macroscopic internal energy transfer, similar to mass and momentum transfers, occurs through nonlinear collisional processes and is not a simple relaxation process described by, e.g., the Landau-Teller equation. Unlike the classical vibrational energy

  7. General multi-group macroscopic modeling for thermo-chemical non-equilibrium gas mixtures

    Science.gov (United States)

    Liu, Yen; Panesi, Marco; Sahai, Amal; Vinokur, Marcel

    2015-04-01

    This paper opens a new door to macroscopic modeling for thermal and chemical non-equilibrium. In a game-changing approach, we discard conventional theories and practices stemming from the separation of internal energy modes and the Landau-Teller relaxation equation. Instead, we solve the fundamental microscopic equations in their moment forms but seek only optimum representations for the microscopic state distribution function that provides converged and time accurate solutions for certain macroscopic quantities at all times. The modeling makes no ad hoc assumptions or simplifications at the microscopic level and includes all possible collisional and radiative processes; it therefore retains all non-equilibrium fluid physics. We formulate the thermal and chemical non-equilibrium macroscopic equations and rate coefficients in a coupled and unified fashion for gases undergoing completely general transitions. All collisional partners can have internal structures and can change their internal energy states after transitions. The model is based on the reconstruction of the state distribution function. The internal energy space is subdivided into multiple groups in order to better describe non-equilibrium state distributions. The logarithm of the distribution function in each group is expressed as a power series in internal energy based on the maximum entropy principle. The method of weighted residuals is applied to the microscopic equations to obtain macroscopic moment equations and rate coefficients succinctly to any order. The model's accuracy depends only on the assumed expression of the state distribution function and the number of groups used and can be self-checked for accuracy and convergence. We show that the macroscopic internal energy transfer, similar to mass and momentum transfers, occurs through nonlinear collisional processes and is not a simple relaxation process described by, e.g., the Landau-Teller equation. Unlike the classical vibrational energy

  8. 40 CFR 799.5025 - Testing consent orders for mixtures without Chemical Abstracts Service Registry Numbers.

    Science.gov (United States)

    2010-07-01

    ... without Chemical Abstracts Service Registry Numbers. 799.5025 Section 799.5025 Protection of Environment... orders for mixtures without Chemical Abstracts Service Registry Numbers. This section sets forth a list of mixtures (with no Chemical Abstracts Service Registry Numbers) which are the subject of...

  9. Hygroscopic behavior of multicomponent organic aerosols and their internal mixtures with ammonium sulfate

    Directory of Open Access Journals (Sweden)

    B. Jing

    2015-08-01

    Full Text Available Water soluble organic compounds (WSOCs are important components of organics in the atmospheric fine particulate matter. Although WSOCs play an important role in the hygroscopicity of aerosols, water uptake behavior of internally mixed WSOC aerosols remains limited characterization. Here, the hygroscopic properties of single component such as levoglucosan, oxalic acid, malonic acid, succinic acid and phthalic acid and multicomponent WSOC aerosols mainly involving oxalic acid are investigated with the hygroscopicity tandem differential mobility analyzer (HTDMA. The coexisting hygroscopic species including levoglucosan, malonic acid and phthalic acid have strong influence on the hygroscopic growth and phase behavior of oxalic acid, even suppress its crystallization completely. The interactions between oxalic acid and levoglucosan are confirmed by infrared spectra. The discrepancies between measured growth factors and predictions from Extended Aerosol Inorganics Model (E-AIM with UNIFAC method and Zdanovskii–Stokes–Robinson (ZSR approach increase at medium and high relative humidity (RH assuming oxalic acid in a solid state. For the internal mixture of oxalic acid with levoglucosan or succinic acid, there is enhanced water uptake at high RH due to positive chemical interactions between solutes. Organic mixture has more complex effect on the hygroscopicity of ammonium sulfate than single species. Although hygroscopic species such as levoglucosan accounts for a small fraction in the multicomponent aerosols, they may still strongly influence the hygroscopic behavior of ammonium sulfate by changing phase state of oxalic acid which plays the role of "intermediate" species. Considering the abundance of oxalic acid in the atmospheric aerosols, its mixtures with hygroscopic species may significantly promote water uptake under high RH conditions and thus affect the cloud condensation nuclei (CCN activity, optical properties and chemical reactivity of

  10. Review of the toxicity of chemical mixtures: Theory, policy, and regulatory practice.

    Science.gov (United States)

    McCarty, L S; Borgert, C J

    2006-07-01

    An analysis of current mixture theory, policy, and practice was conducted by examining standard reference texts, regulatory guidance documents, and journal articles. Although this literature contains useful theoretical concepts, clear definitions of most terminology, and well developed protocols for study design and statistical analysis, no general theoretical basis for the mechanisms and interactions of mixture toxicity could be discerned. There is also a poor understanding of the relationship between exposure-based and internal received dose metrics. This confounds data interpretation and limits reliable determinations of the nature and extent of additivity. The absence of any generally accepted classification scheme for either modes/mechanisms of toxic action or of mechanisms of toxicity interactions is problematic as it produces a cycle in which research and policy are interdependent and mutually limiting. Current regulatory guidance depends heavily on determination of toxicological similarity concluded from the presence of a few prominent constituents, assumed from a common toxicological effect, or presumed from an alleged similar toxic mode/mechanism. Additivity, or the lack of it, is largely based on extrapolation of existing knowledge for single chemicals in this context. Thus, regulatory risk assessment protocols lack authoritative theoretical underpinnings, creating substantial uncertainty. Development of comprehensive classification schemes for modes/mechanisms of toxic action and mechanisms of interaction is needed to ensure a sound theoretical foundation for mixture-related regulatory activity and provide a firm basis for iterative hypothesis development and experimental testing.

  11. Performance Characteristic of Cold Recycled Mixture with Asphalt Emulsion and Chemical Additives

    Directory of Open Access Journals (Sweden)

    Shaowen Du

    2015-01-01

    Full Text Available Three types of chemical additives were used to modify asphalt emulsion recycled mixture. These chemical additives include composite Portland cement (CPC, hydrated lime (HL, and a combination of hydrated lime and ground-granulated blast-furnace slag (GGBF. The influence of different additives on the recycled mixture performance was investigated by volumetric and strength tests, moisture susceptibility test, rutting resistance test, and low temperature bending test. To better understand its performance characteristic, the microstructure images of the recycled mixture were observed by environmental scanning electron microscope (ESEM. Test results demonstrate that the performance improvement of the emulsion recycled mixture depends on the types and content of chemical additives. Several recommendations are presented for the selection of chemical materials. Based on ESEM image analysis, the interface bonding mechanism is proposed to explain the performance characteristic of the recycled mixture with asphalt emulsion and cementitious materials.

  12. Software for analysis of chemical mixtures--composition, occurrence, distribution, and possible toxicity

    Science.gov (United States)

    Scott, Jonathon C.; Skach, Kenneth A.; Toccalino, Patricia L.

    2013-01-01

    The composition, occurrence, distribution, and possible toxicity of chemical mixtures in the environment are research concerns of the U.S. Geological Survey and others. The presence of specific chemical mixtures may serve as indicators of natural phenomena or human-caused events. Chemical mixtures may also have ecological, industrial, geochemical, or toxicological effects. Chemical-mixture occurrences vary by analyte composition and concentration. Four related computer programs have been developed by the National Water-Quality Assessment Program of the U.S. Geological Survey for research of chemical-mixture compositions, occurrences, distributions, and possible toxicities. The compositions and occurrences are identified for the user-supplied data, and therefore the resultant counts are constrained by the user’s choices for the selection of chemicals, reporting limits for the analytical methods, spatial coverage, and time span for the data supplied. The distribution of chemical mixtures may be spatial, temporal, and (or) related to some other variable, such as chemical usage. Possible toxicities optionally are estimated from user-supplied benchmark data. The software for the analysis of chemical mixtures described in this report is designed to work with chemical-analysis data files retrieved from the U.S. Geological Survey National Water Information System but can also be used with appropriately formatted data from other sources. Installation and usage of the mixture software are documented. This mixture software was designed to function with minimal changes on a variety of computer-operating systems. To obtain the software described herein and other U.S. Geological Survey software, visit http://water.usgs.gov/software/.

  13. Modelling of associating mixtures for applications in the oil & gas and chemical industries

    DEFF Research Database (Denmark)

    Kontogeorgis, Georgios; Folas, Georgios; Muro Sunè, Nuria

    2007-01-01

    -alcohol (glycol)-alkanes and certain acid and amine-containing mixtures. Recent results include glycol-aromatic hydrocarbons including multiphase, multicomponent equilibria and gas hydrate calculations in combination with the van der Waals-Platteeuw model. This article will outline some new applications...... of the model of relevance to the petroleum and chemical industries: high pressure vapor-liquid and liquid-liquid equilibrium in alcohol-containing mixtures, mixtures with gas hydrate inhibitors and mixtures with polar and hydrogen bonding chemicals including organic acids. Some comparisons with conventional...

  14. Mixture

    Directory of Open Access Journals (Sweden)

    Silva-Aguilar Martín

    2011-01-01

    Full Text Available Metals are ubiquitous pollutants present as mixtures. In particular, mixture of arsenic-cadmium-lead is among the leading toxic agents detected in the environment. These metals have carcinogenic and cell-transforming potential. In this study, we used a two step cell transformation model, to determine the role of oxidative stress in transformation induced by a mixture of arsenic-cadmium-lead. Oxidative damage and antioxidant response were determined. Metal mixture treatment induces the increase of damage markers and the antioxidant response. Loss of cell viability and increased transforming potential were observed during the promotion phase. This finding correlated significantly with generation of reactive oxygen species. Cotreatment with N-acetyl-cysteine induces effect on the transforming capacity; while a diminution was found in initiation, in promotion phase a total block of the transforming capacity was observed. Our results suggest that oxidative stress generated by metal mixture plays an important role only in promotion phase promoting transforming capacity.

  15. Overview of human health and chemical mixtures: problems facing developing countries.

    OpenAIRE

    2002-01-01

    In developing countries, chemical mixtures within the vicinity of small-scale enterprises, smelters, mines, agricultural areas, toxic waste disposal sites, etc., often present a health hazard to the populations within those vicinities. Therefore, in these countries, there is a need to study the toxicological effects of mixtures of metals, pesticides, and organic compounds. However, the study of mixtures containing substances such as DDT (dichlorodiphenyltrichloroethane, an insecticide banned ...

  16. Automatic NMR-based identification of chemical reaction types in mixtures of co-occurring reactions.

    Science.gov (United States)

    Latino, Diogo A R S; Aires-de-Sousa, João

    2014-01-01

    The combination of chemoinformatics approaches with NMR techniques and the increasing availability of data allow the resolution of problems far beyond the original application of NMR in structure elucidation/verification. The diversity of applications can range from process monitoring, metabolic profiling, authentication of products, to quality control. An application related to the automatic analysis of complex mixtures concerns mixtures of chemical reactions. We encoded mixtures of chemical reactions with the difference between the (1)H NMR spectra of the products and the reactants. All the signals arising from all the reactants of the co-occurring reactions were taken together (a simulated spectrum of the mixture of reactants) and the same was done for products. The difference spectrum is taken as the representation of the mixture of chemical reactions. A data set of 181 chemical reactions was used, each reaction manually assigned to one of 6 types. From this dataset, we simulated mixtures where two reactions of different types would occur simultaneously. Automatic learning methods were trained to classify the reactions occurring in a mixture from the (1)H NMR-based descriptor of the mixture. Unsupervised learning methods (self-organizing maps) produced a reasonable clustering of the mixtures by reaction type, and allowed the correct classification of 80% and 63% of the mixtures in two independent test sets of different similarity to the training set. With random forests (RF), the percentage of correct classifications was increased to 99% and 80% for the same test sets. The RF probability associated to the predictions yielded a robust indication of their reliability. This study demonstrates the possibility of applying machine learning methods to automatically identify types of co-occurring chemical reactions from NMR data. Using no explicit structural information about the reactions participants, reaction elucidation is performed without structure elucidation of

  17. A Method for Quantitative Analysis of Chemical Mixtures with THz Time Domain Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zeng-Yan; JI Te; YU Xiao-Han; XIAO Ti-Qiao; XU Hong-Jie

    2006-01-01

    @@ A method for analysing chemical mixtures quantitatively with terahertz time domain spectroscopy is proposed.The experimental results demonstrate the feasibility of this technique. Transmission coefficient of THz wave at the sample surface is taken into account to improve the analytic precision. Isomer mixtures are chosen as the experimental samples. Compared to similar techniques, the analytic precision could be improved evidently in this method.

  18. Solutions of the chemical kinetic equations for initially inhomogeneous mixtures.

    Science.gov (United States)

    Hilst, G. R.

    1973-01-01

    Following the recent discussions by O'Brien (1971) and Donaldson and Hilst (1972) of the effects of inhomogeneous mixing and turbulent diffusion on simple chemical reaction rates, the present report provides a more extensive analysis of when inhomogeneous mixing has a significant effect on chemical reaction rates. The analysis is then extended to the development of an approximate chemical sub-model which provides much improved predictions of chemical reaction rates over a wide range of inhomogeneities and pathological distributions of the concentrations of the reacting chemical species. In particular, the development of an approximate representation of the third-order correlations of the joint concentration fluctuations permits closure of the chemical sub-model at the level of the second-order moments of these fluctuations and the mean concentrations.

  19. MIXTURES OF THYROID DISRUPTING CHEMICALS: TESTING ADDITIVITY OF HEPATIC INDUCERS AND THYROID PEROXIDASE INHIBITORS.

    Science.gov (United States)

    Humans are exposed to chemical mixtures via diet, occupation, and the environment. Previous data demonstrated that low doses of polycyclic halogenated aromatic hydrocarbons (PHAHs) acting through similar mechanisms result in an additive reduction of thyroxine (T4). If xenobioti...

  20. Chemical equilibrium in high pressure molecular fluid mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, M.S.

    1993-09-01

    The N{sub atoms}PT Monte Carlo simulation method has been reformulated to incorporate multiple species and chemical reactions with changes in total number of molecules. While maintaining a constant number of each type of atom, the number of molecules is changed by turning on and off the interactions of any particular position with other molecules. Chemical reactions are allowed as a correlated move of atoms to differnt molecular locations. Equilibrium chemical composition is determined as an average over the simulation along with equation of state quantities. A large set of simulations has been made with the system N{sub 2} + O{sub 2} {rightleftharpoons} NO covering a wide range in P and T. Both Hugoniot states and the CJ point have been determined and are shown to be sensitive to the potentials between unlike species.

  1. Booknotes: Chemical Research Faculties: An International Directory

    Science.gov (United States)

    Kauffman, George B.

    1997-08-01

    American Chemical Society: Washington, DC, 1996. xlv + 1248 pp. 22.1x28.2 cm. ISBN 0-8412-3301-2. $199.95 (hb). This comprehensive source of information on research in chemistry and chemistry-related areas conducted by faculty members worldwide in institutions that grant advanced degrees gives the same type of information on an international scale that the ACS Directory of Graduate Research (DGR) (Kauffman, G. B. J. Chem. Educ. 1996, 73, A136) provides for United States and Canadian institutions. Designed to give users sufficient information to locate a colleague, whether known to them or not, by country, academic institution, or name, this new, updated, partially rearranged third edition of Chemical Research Faculties (CRF) contains more than an additional 75 percent of the volume of information in the second (1988) edition (Kauffman, G. B. J. Chem. Educ. 1989, 66, A48). It contains data on 17,370 faculty members (compared to 11,500 in the second edition), with one or two recent representative publications, from 2,182 institutions (compared to 1,922 in the second edition) in 113 countries arranged alphabetically from Afghanistan to Zimbabwe. A minor shortcoming compared to the last edition is the deletion of the index of faculty by research subjects, which, as a contributing editor to several journals, I found useful in locating possible referees with specific areas of expertise.

  2. Perfluorononanoic acid in combination with 14 chemicals exerts low-dose mixture effects in rats

    DEFF Research Database (Denmark)

    Hadrup, Niels; Pedersen, Mikael; Skov, Kasper;

    2016-01-01

    Humans are simultaneously exposed to several chemicals that act jointly to induce mixture effects. At doses close to or higher than no-observed adverse effect levels, chemicals usually act additively in experimental studies. However, we are lacking knowledge on the importance of exposure to compl...

  3. 40 CFR 370.14 - How do I report mixtures containing hazardous chemicals?

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 27 2010-07-01 2010-07-01 false How do I report mixtures containing hazardous chemicals? 370.14 Section 370.14 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SUPERFUND, EMERGENCY PLANNING, AND COMMUNITY RIGHT-TO-KNOW PROGRAMS HAZARDOUS CHEMICAL REPORTING: COMMUNITY RIGHT-TO-KNOW Who Must Comply...

  4. A generalized physiologically-based toxicokinetic modeling system for chemical mixtures containing metals

    Directory of Open Access Journals (Sweden)

    Isukapalli Sastry S

    2010-06-01

    Full Text Available Abstract Background Humans are routinely and concurrently exposed to multiple toxic chemicals, including various metals and organics, often at levels that can cause adverse and potentially synergistic effects. However, toxicokinetic modeling studies of exposures to these chemicals are typically performed on a single chemical basis. Furthermore, the attributes of available models for individual chemicals are commonly estimated specifically for the compound studied. As a result, the available models usually have parameters and even structures that are not consistent or compatible across the range of chemicals of concern. This fact precludes the systematic consideration of synergistic effects, and may also lead to inconsistencies in calculations of co-occurring exposures and corresponding risks. There is a need, therefore, for a consistent modeling framework that would allow the systematic study of cumulative risks from complex mixtures of contaminants. Methods A Generalized Toxicokinetic Modeling system for Mixtures (GTMM was developed and evaluated with case studies. The GTMM is physiologically-based and uses a consistent, chemical-independent physiological description for integrating widely varying toxicokinetic models. It is modular and can be directly "mapped" to individual toxicokinetic models, while maintaining physiological consistency across different chemicals. Interaction effects of complex mixtures can be directly incorporated into the GTMM. Conclusions The application of GTMM to different individual metals and metal compounds showed that it explains available observational data as well as replicates the results from models that have been optimized for individual chemicals. The GTMM also made it feasible to model toxicokinetics of complex, interacting mixtures of multiple metals and nonmetals in humans, based on available literature information. The GTMM provides a central component in the development of a "source

  5. Chemical constituents of marijuana: the complex mixture of natural cannabinoids.

    Science.gov (United States)

    Elsohly, Mahmoud A; Slade, Desmond

    2005-12-22

    The cannabis plant (Cannabis sativa L.) and products thereof (such as marijuana, hashish and hash oil) have a long history of use both as a medicinal agent and intoxicant. Over the last few years there have been an active debate regarding the medicinal aspects of cannabis. Currently cannabis products are classified as Schedule I drugs under the Drug Enforcement Administration (DEA) Controlled Substances act, which means that the drug is only available for human use as an investigational drug. In addition to the social aspects of the use of the drug and its abuse potential, the issue of approving it as a medicine is further complicated by the complexity of the chemical make up of the plant. This manuscript discusses the chemical constituents of the plant with particular emphasis on the cannabinoids as the class of compounds responsible for the drug's psychological properties.

  6. Overview of human health and chemical mixtures: problems facing developing countries.

    Science.gov (United States)

    Yáñ ez, Leticia; Ortiz, Deogracias; Calderón, Jaqueline; Batres, Lilia; Carrizales, Leticia; Mejía, Jesús; Martínez, Lourdes; García-Nieto, Edelmira; Díaz-Barriga, Fernando

    2002-01-01

    In developing countries, chemical mixtures within the vicinity of small-scale enterprises, smelters, mines, agricultural areas, toxic waste disposal sites, etc., often present a health hazard to the populations within those vicinities. Therefore, in these countries, there is a need to study the toxicological effects of mixtures of metals, pesticides, and organic compounds. However, the study of mixtures containing substances such as DDT (dichlorodiphenyltrichloroethane, an insecticide banned in developed nations), and mixtures containing contaminants such as fluoride (of concern only in developing countries) merit special attention. Although the studies may have to take into account simultaneous exposures to metals and organic compounds, there is also a need to consider the interaction between chemicals and other specific factors such as nutritional conditions, alcoholism, smoking, infectious diseases, and ethnicity. PMID:12634117

  7. Perinatal exposure to mixtures of anti-androgenic chemicals causes proliferative lesions in rat prostate

    DEFF Research Database (Denmark)

    Boberg, Julie; Johansson, Hanna Katarina Lilith; Hadrup, Niels

    2015-01-01

    BACKGROUND: Elevated levels of endogenous or exogenous estrogens during fetal life can induce permanent disturbances in prostate growth and predispose to precancerous lesions. Recent studies have indicated that also early anti-androgen exposure may affect prostate cancer risk. METHODS: We examined...... disrupters relevant for human exposure was found to elicit persistent effects on the rat prostate following perinatal exposure, suggesting that human perinatal exposure to environmental chemicals may increase the risk of prostate cancer later in life. Prostate....... the influence of perinatal exposure to mixtures of anti-androgenic and estrogenic chemicals on prostate development. Wistar rats were exposed from gestation day 7 to postnatal day 22 to a mixture of 8 anti-androgenic compounds (AAMix), a mixture of four estrogenic compounds (EMix), or paracetamol or a mixture...

  8. Assessing the carcinogenic potential of low-dose exposures to chemical mixtures in the environment: the challenge ahead

    Science.gov (United States)

    Goodson, William H.; Lowe, Leroy; Carpenter, David O.; Gilbertson, Michael; Manaf Ali, Abdul; Lopez de Cerain Salsamendi, Adela; Lasfar, Ahmed; Carnero, Amancio; Azqueta, Amaya; Amedei, Amedeo; Charles, Amelia K.; Collins, Andrew R.; Ward, Andrew; Salzberg, Anna C.; Colacci, Anna Maria; Olsen, Ann-Karin; Berg, Arthur; Barclay, Barry J.; Zhou, Binhua P.; Blanco-Aparicio, Carmen; Baglole, Carolyn J.; Dong, Chenfang; Mondello, Chiara; Hsu, Chia-Wen; Naus, Christian C.; Yedjou, Clement; Curran, Colleen S.; Laird, Dale W.; Koch, Daniel C.; Carlin, Danielle J.; Felsher, Dean W.; Roy, Debasish; Brown, Dustin G.; Ratovitski, Edward; Ryan, Elizabeth P.; Corsini, Emanuela; Rojas, Emilio; Moon, Eun-Yi; Laconi, Ezio; Marongiu, Fabio; Al-Mulla, Fahd; Chiaradonna, Ferdinando; Darroudi, Firouz; Martin, Francis L.; Van Schooten, Frederik J.; Goldberg, Gary S.; Wagemaker, Gerard; Nangami, Gladys N.; Calaf, Gloria M.; Williams, Graeme P.; Wolf, Gregory T.; Koppen, Gudrun; Brunborg, Gunnar; Lyerly, H. Kim; Krishnan, Harini; Ab Hamid, Hasiah; Yasaei, Hemad; Sone, Hideko; Kondoh, Hiroshi; Salem, Hosni K.; Hsu, Hsue-Yin; Park, Hyun Ho; Koturbash, Igor; Miousse, Isabelle R.; Scovassi, A.Ivana; Klaunig, James E.; Vondráček, Jan; Raju, Jayadev; Roman, Jesse; Wise, John Pierce; Whitfield, Jonathan R.; Woodrick, Jordan; Christopher, Joseph A.; Ochieng, Josiah; Martinez-Leal, Juan Fernando; Weisz, Judith; Kravchenko, Julia; Sun, Jun; Prudhomme, Kalan R.; Narayanan, Kannan Badri; Cohen-Solal, Karine A.; Moorwood, Kim; Gonzalez, Laetitia; Soucek, Laura; Jian, Le; D’Abronzo, Leandro S.; Lin, Liang-Tzung; Li, Lin; Gulliver, Linda; McCawley, Lisa J.; Memeo, Lorenzo; Vermeulen, Louis; Leyns, Luc; Zhang, Luoping; Valverde, Mahara; Khatami, Mahin; Romano, Maria Fiammetta; Chapellier, Marion; Williams, Marc A.; Wade, Mark; Manjili, Masoud H.; Lleonart, Matilde E.; Xia, Menghang; Gonzalez Guzman, Michael J.; Karamouzis, Michalis V.; Kirsch-Volders, Micheline; Vaccari, Monica; Kuemmerle, Nancy B.; Singh, Neetu; Cruickshanks, Nichola; Kleinstreuer, Nicole; van Larebeke, Nik; Ahmed, Nuzhat; Ogunkua, Olugbemiga; Krishnakumar, P.K.; Vadgama, Pankaj; Marignani, Paola A.; Ghosh, Paramita M.; Ostrosky-Wegman, Patricia; Thompson, Patricia A.; Dent, Paul; Heneberg, Petr; Darbre, Philippa; Leung, Po Sing; Nangia-Makker, Pratima; Cheng, Qiang (Shawn); Robey, R.Brooks; Al-Temaimi, Rabeah; Roy, Rabindra; Andrade-Vieira, Rafaela; Sinha, Ranjeet K.; Mehta, Rekha; Vento, Renza; Di Fiore, Riccardo; Ponce-Cusi, Richard; Dornetshuber-Fleiss, Rita; Nahta, Rita; Castellino, Robert C.; Palorini, Roberta; Hamid, Roslida A.; Langie, Sabine A.S.; Eltom, Sakina E.; Brooks, Samira A.; Ryeom, Sandra; Wise, Sandra S.; Bay, Sarah N.; Harris, Shelley A.; Papagerakis, Silvana; Romano, Simona; Pavanello, Sofia; Eriksson, Staffan; Forte, Stefano; Casey, Stephanie C.; Luanpitpong, Sudjit; Lee, Tae-Jin; Otsuki, Takemi; Chen, Tao; Massfelder, Thierry; Sanderson, Thomas; Guarnieri, Tiziana; Hultman, Tove; Dormoy, Valérian; Odero-Marah, Valerie; Sabbisetti, Venkata; Maguer-Satta, Veronique; Rathmell, W.Kimryn; Engström, Wilhelm; Decker, William K.; Bisson, William H.; Rojanasakul, Yon; Luqmani, Yunus; Chen, Zhenbang; Hu, Zhiwei

    2015-01-01

    Lifestyle factors are responsible for a considerable portion of cancer incidence worldwide, but credible estimates from the World Health Organization and the International Agency for Research on Cancer (IARC) suggest that the fraction of cancers attributable to toxic environmental exposures is between 7% and 19%. To explore the hypothesis that low-dose exposures to mixtures of chemicals in the environment may be combining to contribute to environmental carcinogenesis, we reviewed 11 hallmark phenotypes of cancer, multiple priority target sites for disruption in each area and prototypical chemical disruptors for all targets, this included dose-response characterizations, evidence of low-dose effects and cross-hallmark effects for all targets and chemicals. In total, 85 examples of chemicals were reviewed for actions on key pathways/mechanisms related to carcinogenesis. Only 15% (13/85) were found to have evidence of a dose-response threshold, whereas 59% (50/85) exerted low-dose effects. No dose-response information was found for the remaining 26% (22/85). Our analysis suggests that the cumulative effects of individual (non-carcinogenic) chemicals acting on different pathways, and a variety of related systems, organs, tissues and cells could plausibly conspire to produce carcinogenic synergies. Additional basic research on carcinogenesis and research focused on low-dose effects of chemical mixtures needs to be rigorously pursued before the merits of this hypothesis can be further advanced. However, the structure of the World Health Organization International Programme on Chemical Safety ‘Mode of Action’ framework should be revisited as it has inherent weaknesses that are not fully aligned with our current understanding of cancer biology. PMID:26106142

  9. Study of sensory diversity and redundancy to encode for chemical mixtures

    Science.gov (United States)

    Gutiérrez-Gálvez, Agustín; Fernandez, Luis; Marco, Santiago

    2011-09-01

    Inspired by sensory diversity and redundancy at the olfactory epithelium, we have built a large chemical sensor array based on commercial MOX sensors. Different sensor families along with temperature modulation accounts for sensory diversity, whereas sensors of the same family combined with different load resistors provide redundancy to the system. To study the encoding of odor mixtures, a data collection consisting on the response of the array to 3 binary mixtures of ethanol, acetone, and butanone with 18 different concentration ratios is obtained.

  10. Chemical contaminants on DOE lands and selection of contaminant mixtures for subsurface science research

    Energy Technology Data Exchange (ETDEWEB)

    Riley, R.G.; Zachara, J.M. [Pacific Northwest Lab., Richland, WA (United States)

    1992-04-01

    This report identifies individual contaminants and contaminant mixtures that have been measured in the ground at 91 waste sites at 18 US Department of Energy (DOE) facilities within the weapons complex. The inventory of chemicals and mixtures was used to identify generic chemical mixtures to be used by DOE`s Subsurface Science Program in basic research on the subsurface geochemical and microbiological behavior of mixed contaminants (DOE 1990a and b). The generic mixtures contain specific radionuclides, metals, organic ligands, organic solvents, fuel hydrocarbons, and polychlorinated biphenyls (PCBs) in various binary and ternary combinations. The mixtures are representative of in-ground contaminant associations at DOE facilities that are likely to exhibit complex geochemical behavior as a result of intercontaminant reactions and/or microbiologic activity stimulated by organic substances. Use of the generic mixtures will focus research on important mixed contaminants that are likely to be long-term problems at DOE sites and that will require cleanup or remediation. The report provides information on the frequency of associations among different chemicals and compound classes at DOE waste sites that require remediation.

  11. Chemical contaminants on DOE lands and selection of contaminant mixtures for subsurface science research

    Energy Technology Data Exchange (ETDEWEB)

    Riley, R.G.; Zachara, J.M. (Pacific Northwest Lab., Richland, WA (United States))

    1992-04-01

    This report identifies individual contaminants and contaminant mixtures that have been measured in the ground at 91 waste sites at 18 US Department of Energy (DOE) facilities within the weapons complex. The inventory of chemicals and mixtures was used to identify generic chemical mixtures to be used by DOE's Subsurface Science Program in basic research on the subsurface geochemical and microbiological behavior of mixed contaminants (DOE 1990a and b). The generic mixtures contain specific radionuclides, metals, organic ligands, organic solvents, fuel hydrocarbons, and polychlorinated biphenyls (PCBs) in various binary and ternary combinations. The mixtures are representative of in-ground contaminant associations at DOE facilities that are likely to exhibit complex geochemical behavior as a result of intercontaminant reactions and/or microbiologic activity stimulated by organic substances. Use of the generic mixtures will focus research on important mixed contaminants that are likely to be long-term problems at DOE sites and that will require cleanup or remediation. The report provides information on the frequency of associations among different chemicals and compound classes at DOE waste sites that require remediation.

  12. Mixtures of environmentally relevant endocrine disrupting chemicals affect mammary gland development in female and male rats.

    Science.gov (United States)

    Mandrup, Karen Riiber; Johansson, Hanna Katarina Lilith; Boberg, Julie; Pedersen, Anne Stilling; Mortensen, Mette Sidsel; Jørgensen, Jennifer Solgaard; Vinggaard, Anne Marie; Hass, Ulla

    2015-07-01

    Estrogenic chemicals are able to alter mammary gland development in female rodents, but little is known on the effects of anti-androgens and mixtures of endocrine disrupting chemicals (EDCs) with dissimilar modes of action. Pregnant rat dams were exposed during gestation and lactation to mixtures of environmentally relevant EDCs with estrogenic, anti-androgenic or dissimilar modes of action (TotalMix) of 100-, 200- or 450-fold high end human intake estimates. Mammary glands of prepubertal and adult female and male offspring were examined. Oestrogens increased mammary outgrowth in prepubertal females and the mRNA level of matrix metalloproteinase-3, which may be a potential biomarker for increased outgrowth. Mixtures of EDCs gave rise to ductal hyperplasia in adult males. Adult female mammary glands of the TotalMix group showed morphological changes possibly reflecting increased prolactin levels. In conclusion both estrogenic and anti-androgenic chemicals given during foetal life and lactation affected mammary glands in the offspring.

  13. Should the scope of human mixture risk assessment span legislative/regulatory silos for chemicals?

    Science.gov (United States)

    Evans, Richard M; Martin, Olwenn V; Faust, Michael; Kortenkamp, Andreas

    2016-02-01

    Current chemicals regulation operates almost exclusively on a chemical-by-chemical basis, however there is concern that this approach may not be sufficiently protective if two or more chemicals have the same toxic effect. Humans are indisputably exposed to more than one chemical at a time, for example to the multiple chemicals found in food, air and drinking water, and in household and consumer products, and in cosmetics. Assessment of cumulative risk to human health and/or the environment from multiple chemicals and routes can be done in a mixture risk assessment (MRA). Whilst there is a broad consensus on the basic science of mixture toxicology, the path to regulatory implementation of MRA within chemical risk assessment is less clear. In this discussion piece we pose an open question: should the scope of human MRA cross legislative remits or 'silos'? We define silos as, for instance, legislation that defines risk assessment practice for a subset of chemicals, usually on the basis of substance/product, media or process orientation. Currently any form of legal mandate for human MRA in the EU is limited to only a few pieces of legislation. We describe two lines of evidence, illustrated with selected examples, that are particularly pertinent to this question: 1) evidence that mixture effects have been shown for chemicals regulated in different silos and 2) evidence that humans are co-exposed to chemicals from different silos. We substantiate the position that, because there is no reason why chemicals allocated to specific regulatory silos would have non-overlapping risk profiles, then there is also no reason to expect that MRA limited only to chemicals within one silo can fully capture the risk that may be present to human consumers. Finally, we discuss possible options for implementation of MRA and we hope to prompt wider discussion of this issue.

  14. 40 CFR 799.5000 - Testing consent orders for substances and mixtures with Chemical Abstract Service Registry Numbers.

    Science.gov (United States)

    2010-07-01

    ... and mixtures with Chemical Abstract Service Registry Numbers. 799.5000 Section 799.5000 Protection of... Testing consent orders for substances and mixtures with Chemical Abstract Service Registry Numbers. This... adopted under 40 CFR part 790. Listed below in Chemical Abstract Service (CAS) Registry Number order...

  15. Insights into synergistic interactions in binary mixtures of chemical permeation enhancers for transdermal drug delivery.

    Science.gov (United States)

    Karande, Pankaj; Jain, Amit; Mitragotri, Samir

    2006-09-28

    Chemical permeation enhancers (CPEs) are known to increase skin permeability to therapeutic drugs. Single chemicals, however, offer limited enhancements of skin permeability. Mixtures of chemicals can overcome this limitation owing to their synergistic interactions. However, identification of potent mixtures of chemicals requires screening of a large number of formulations. Discovery of CPE mixtures can be significantly accelerated by identifying patterns that occur in the existing data on CPEs. In this study, we systematically mine through a huge database on skin permeabilizing effect of over 4000 binary formulations generated by high throughput screening and extract general principles that govern the effect of binary combinations of chemicals on skin's barrier properties. Potencies and synergies of these formulations are analyzed to identify the role played by the formulation composition and chemistry. The analysis reveals several intuitive but some largely non-intuitive trends. For example, formulations made from enhancer mixtures are most potent when participating moieties are present in nearly equal fractions. Methyl pyrrolidone, a small molecule, is particularly effective in forming potent and synergistic enhancer formulations, and zwitterionic surfactants are more likely to feature in potent enhancers. Simple but invaluable rules like these will provide guiding principles for designing libraries to further speed up the formulation discovery process.

  16. Disentangling the developmental and neurobehavioural effects of perinatal exposure to a chemical mixture found in blood of Arctic populations: differential toxicity of mixture components

    Energy Technology Data Exchange (ETDEWEB)

    Bowers, W.; Nakai, J.; Yagminas, A.; Chu, I.; Moir, D. [Health Canada (Canada)

    2004-09-15

    The current study was designed to evaluate the neurobehavioral effects of perinatal exposure to a chemical mixture that is based on relative concentrations of persistent organic pollutants found in the blood of Canadian Arctic populations and contains 14 PCB congeners, 12 organochlorine pesticides and methyl mercury. This study compared the effects of the complete mixture with the effects of three major components of the mixture (the PCB component, the organochlorine pesticide component, and the methyl mercury component). By examining a range of neurobehavioural functions over development we also determine if specific neurobehavioural disturbances produced by the mixture can be attributed to components of the mixture and if neurobehavioural effects produced by components of the mixture are altered by concurrent exposure to other components in the mixture. Ninety-two nulliparious female Sprague-Dawley rats served as subjects.

  17. Reacting gas mixtures in the state-to-state approach: The chemical reaction rates

    Energy Technology Data Exchange (ETDEWEB)

    Kustova, Elena V. [Department of Mathematics and Mechanics, Saint Petersburg State University, 198504 Universitetskiy pr., 28, Saint Petersburg (Russian Federation); Kremer, Gilberto M. [Departamento de Física, Universidade Federal do Paraná, Caixa Postal 19044, 81531-980 Curitiba (Brazil)

    2014-12-09

    In this work chemically reacting mixtures of viscous flows are analyzed within the framework of Boltzmann equation. By applying a modified Chapman-Enskog method to the system of Boltzmann equations general expressions for the rates of chemical reactions and vibrational energy transitions are determined as functions of two thermodynamic forces: the velocity divergence and the affinity. As an application chemically reacting mixtures of N{sub 2} across a shock wave are studied, where the first lowest vibrational states are taken into account. Here we consider only the contributions from the first four single quantum vibrational-translational energy transitions. It is shown that the contribution to the chemical reaction rate related to the affinity is much larger than that of the velocity divergence.

  18. Reacting gas mixtures in the state-to-state approach: The chemical reaction rates

    Science.gov (United States)

    Kustova, Elena V.; Kremer, Gilberto M.

    2014-12-01

    In this work chemically reacting mixtures of viscous flows are analyzed within the framework of Boltzmann equation. By applying a modified Chapman-Enskog method to the system of Boltzmann equations general expressions for the rates of chemical reactions and vibrational energy transitions are determined as functions of two thermodynamic forces: the velocity divergence and the affinity. As an application chemically reacting mixtures of N2 across a shock wave are studied, where the first lowest vibrational states are taken into account. Here we consider only the contributions from the first four single quantum vibrational-translational energy transitions. It is shown that the contribution to the chemical reaction rate related to the affinity is much larger than that of the velocity divergence.

  19. Chemical mixture toxicology: from descriptive to mechanistic, and going on to in silico toxicology.

    Science.gov (United States)

    Yang, Raymond S H; El-Masri, Hisham A; Thomas, Russell S; Dobrev, Ivan D; Dennison, James E; Bae, Dong-Soon; Campain, Julie A; Liao, Kai H; Reisfeld, Brad; Andersen, Melvin E; Mumtaz, Moiz

    2004-11-01

    Because of the pioneering vision of certain leaders in the biomedical field, the last two decades witnessed rapid advances in the area of chemical mixture toxicology. Earlier studies utilized conventional toxicology protocol and methods, and they were mainly descriptive in nature. Two good examples might be the parallel series of studies conducted by the U.S. National Toxicology Program and TNO in The Netherlands, respectively. As a natural course of progression, more and more sophistication was incorporated into the toxicology studies of chemical mixtures. Thus, at least the following seven areas of scientific achievements in chemical mixture toxicology are evident in the literature: (a) the application of better and more robust statistical methods; (b) the exploration and incorporation of mechanistic bases for toxicological interactions; (c) the application of physiologically based pharmacokinetic/pharmacodynamic (PBPK/PD) modeling; (d) the studies on more complex chemical mixtures; (e) the use of science-based risk assessment approaches; (f) the utilization of functional genomics; and (g) the application of technology. Examples are given for the discussion of each of these areas. Two important concepts emerged from these studies and they are: (1) dose-dependent toxicologic interactions; and (2) "interaction thresholds". Looking into the future, one of the most challenging areas in chemical mixture research is finding the answer to the question "when one tries to characterize the health effects of chemical mixtures, how does one deal with the infinite number of combination of chemicals, and other possible stressors?" Undoubtedly, there will be many answers from different groups of researchers. Our answer, however, is first to focus on the finite (biological processes) rather than the infinite (combinations of chemical mixtures and multiple stressors). The idea is that once we know a normal biological process(es), all stimuli and insults from external stressors

  20. On the formation of new ignition kernels in the chemically active dispersed mixtures

    Science.gov (United States)

    Ivanov, M. F.; Kiverin, A. D.

    2015-11-01

    The specific features of the combustion waves propagating through the channels filled with chemically active gaseous mixture and non-uniformly suspended micro particles are studied numerically. It is shown that the heat radiated by the hot products, absorbed by the micro particles and then transferred to the environmental fresh mixture can be the source of new ignition kernels in the regions of particles' clusters. Herewith the spatial distribution of the particles determines the features of combustion regimes arising in these kernels. One can highlight the multi-kernel ignition in the polydisperse mixtures and ignition of the combustion regimes with shocks and detonation formation in the mixtures with pronounced gradients of microparticles concentration.

  1. Additive mixture effects of estrogenic chemicals in human cell-based assays can be influenced by inclusion of chemicals with differing effect profiles.

    Directory of Open Access Journals (Sweden)

    Richard Mark Evans

    Full Text Available A growing body of experimental evidence indicates that the in vitro effects of mixtures of estrogenic chemicals can be well predicted from the estrogenicity of their components by the concentration addition (CA concept. However, some studies have observed small deviations from CA. Factors affecting the presence or observation of deviations could include: the type of chemical tested; number of mixture components; mixture design; and assay choice. We designed mixture experiments that address these factors, using mixtures with high numbers of components, chemicals from diverse chemical groups, assays with different in vitro endpoints and different mixture designs and ratios. Firstly, the effects of mixtures composed of up to 17 estrogenic chemicals were examined using estrogenicity assays with reporter-gene (ERLUX and cell proliferation (ESCREEN endpoints. Two mixture designs were used: 1 a 'balanced' design with components present in proportion to a common effect concentration (e.g. an EC(10 and 2 a 'non-balanced' design with components in proportion to potential human tissue concentrations. Secondly, the individual and simultaneous ability of 16 potential modulator chemicals (each with minimal estrogenicity to influence the assay outcome produced by a reference mixture of estrogenic chemicals was examined. Test chemicals included plasticizers, phthalates, metals, PCBs, phytoestrogens, PAHs, heterocyclic amines, antioxidants, UV filters, musks, PBDEs and parabens. In all the scenarios tested, the CA concept provided a good prediction of mixture effects. Modulation studies revealed that chemicals possessing minimal estrogenicity themselves could reduce (negatively modulate the effect of a mixture of estrogenic chemicals. Whether the type of modulation we observed occurs in practice most likely depends on the chemical concentrations involved, and better information is required on likely human tissue concentrations of estrogens and of potential

  2. AGONISTIC SENSORY EFFECTS OF AIRBORNE CHEMICALS IN MIXTURES: ODOR, NASAL PUNGENCY, AND EYE IRRITATION

    Science.gov (United States)

    Threshold responses of odor, nasal pungency (irritation), and eye irritation were measured for single chemicals (1-propanol, 1-hexanol, ethyl acetate, heptyl acetate, 2-pentanone, 2-heptanone, toluene, ethyl benzene, and propyl benzene) and mixtures of them (two three-component m...

  3. Spectral analysis of the light scattered from a chemically relaxing fluid: A ternary mixture

    NARCIS (Netherlands)

    Carle, D.L.; Laidlaw, W.G.; Lekkerkerker, H.N.W.

    1974-01-01

    The spectral distribution of light scattered by a ternary fluid mixture containing two chemically reactive species and one nonreactive species is considered and a normal mode analysis is carried out for a range of k-values for which the pressure fluctuations are decoupled from those in entropy and c

  4. Enhancing the chemical mixture methodology in emergency preparedness and consequence assessment analysis.

    Science.gov (United States)

    Yu, Xiao-Ying; Glantz, Clifford S; Yao, Juan; He, Hua; Petrocchi, Achille J; Craig, Douglas K; Ciolek, John T; Booth, Alexander E

    2013-11-16

    Emergency preparedness personnel at U.S. Department of Energy (DOE) facilities use the chemical mixture methodology (CMM) to estimate the potential health impacts to workers and the public from the unintended airborne release of chemical mixtures. The CMM uses a Hazard Index (HI) for each chemical in a mixture to compare a chemical's concentration at a receptor location to an appropriate concentration limit for that chemical. This limit is typically based on Protection Action Criteria (PAC) values developed and published by the DOE. As a first cut, the CMM sums the HIs for all the chemicals in a mixture to conservatively estimate their combined health impact. A cumulative HI>1.0 represents a concentration exceeding the concentration limit and indicates the potential for adverse health effects. Next, Health Code Numbers (HCNs) are used to identify the target organ systems that may be impacted by exposure to each chemical in a mixture. The sum of the HIs for the maximally impacted target organ system is used to provide a refined, though still conservative, estimate of the potential for adverse health effects from exposure to the chemical mixture. This paper explores approaches to enhance the effectiveness of the CMM by using HCN weighting factors. A series of 24 case studies have been defined to evaluate both the existing CMM and three new approaches for improving the CMM. The first approach uses a set of HCN weighting factors that are applied based on the priority ranking of the HCNs for each chemical. The second approach uses weighting factors based on the priority rankings of the HCNs established for a given type of concentration limit. The third approach uses weighting factors that are based on the exposure route used to derive PAC values and a priority ranking of the HCNs (the same ranking as used in the second approach). Initial testing indicates that applying weighting factors increases the effectiveness of the CMM in general, though care must be taken to

  5. Overview of international programmes on the assessment of existing chemicals

    NARCIS (Netherlands)

    Wezel AP van; CSR

    1999-01-01

    This overview presents the major international programmes in which assessment of chemicals takes place. The appendix lists the chemicals assessed in the various programmes and sites the planning for the coming years. The overlap with the Dutch policy on chemicals is also overviewed.

  6. From single chemicals to mixtures--reproductive effects of levonorgestrel and ethinylestradiol on the fathead minnow.

    Science.gov (United States)

    Runnalls, Tamsin J; Beresford, Nicola; Kugathas, Subramaniam; Margiotta-Casaluci, Luigi; Scholze, Martin; Scott, Alexander P; Sumpter, John P

    2015-12-01

    The aquatic environment is polluted with thousands of chemicals. It is currently unclear which of these pose a significant threat to aquatic biota. The typical exposure scenario is now represented by a widespread blanket of contamination composed of myriads of individual pollutants-each typically present at a low concentration. The synthetic steroids, 17α-ethinylestradiol and levonorgestrel, have been widely reported to be present in the aquatic environment in the low ng to sub-ng/l range. They are widely used in contraceptive formulations, both individually and in combination. Our research employed the fathead minnow (Pimephales promelas) 21 day 'pair-breeding' assay to assess reproductive output when pairs of fish were exposed to the single chemicals at low environmentally relevant concentrations, and then to a binary mixture of them. A variety of endpoints were assessed, including egg production, which was inhibited in a concentration-dependent manner by both the individual chemicals and the mixture. Significant, sex specific effects were also seen with both chemicals, at differing levels of biological organisation. Plasma concentrations of EE2 and levonorgestrel were predicted and in the case of levonorgestrel measured, and compared with the human therapeutic plasma concentrations (Read-Across approach) to support the interpretation of the results. A novel quantitative method was developed for the data analysis, which ensured a suitable endpoint for the comparative mixture assessment. This approach compares the reproductive performance from individual pairs of fish during chemical exposure to its pre-treatment performance. The responses from the empirical mixture study were compared to predictions derived from the single substance data. We hypothesised combined responses which were best described by the concept of concentration addition, and found no clear indications against this additivity expectation. However, the effect profiles support the current

  7. Toxicogenomic responses in rainbow trout (Oncorhynchus mykiss) hepatocytes exposed to model chemicals and a synthetic mixture

    Energy Technology Data Exchange (ETDEWEB)

    Finne, E.F. [Norwegian Institute for Water Research, Gaustadalleen 21, N-0349 Oslo (Norway) and University of Oslo, Department of Biology, P.O. Box 1066, Blindern, N-0316 Oslo (Norway)]. E-mail: eivind.finne@niva.no; Cooper, G.A. [Centre for Biomedical Research, University of Victoria, BC V8P5C2 (Canada); Koop, B.F. [Centre for Biomedical Research, University of Victoria, BC V8P5C2 (Canada); Hylland, K. [Norwegian Institute for Water Research, Gaustadalleen 21, N-0349 Oslo (Norway); University of Oslo, Department of Biology, P.O. Box 1066, Blindern, N-0316 Oslo (Norway); Tollefsen, K.E. [Norwegian Institute for Water Research, Gaustadalleen 21, N-0349 Oslo (Norway)

    2007-03-10

    As more salmon gene expression data has become available, the cDNA microarray platform has emerged as an appealing alternative in ecotoxicological screening of single chemicals and environmental samples relevant to the aquatic environment. This study was performed to validate biomarker gene responses of in vitro cultured rainbow trout (Oncorhynchus mykiss) hepatocytes exposed to model chemicals, and to investigate effects of mixture toxicity in a synthetic mixture. Chemicals used for 24 h single chemical- and mixture exposures were 10 nM 17{alpha}-ethinylestradiol (EE2), 0.75 nM 2,3,7,8-tetrachloro-di-benzodioxin (TCDD), 100 {mu}M paraquat (PQ) and 0.75 {mu}M 4-nitroquinoline-1-oxide (NQO). RNA was isolated from exposed cells, DNAse treated and quality controlled before cDNA synthesis, fluorescent labelling and hybridisation to a 16k salmonid microarray. The salmonid 16k cDNA array identified differential gene expression predictive of exposure, which could be verified by quantitative real time PCR. More precisely, the responses of biomarker genes such as cytochrome p4501A and UDP-glucuronosyl transferase to TCDD exposure, glutathione reductase and gammaglutamyl cysteine synthetase to paraquat exposure, as well as vitellogenin and vitelline envelope protein to EE2 exposure validated the use of microarray applied to RNA extracted from in vitro exposed hepatocytes. The mutagenic compound NQO did not result in any change in gene expression. Results from exposure to a synthetic mixture of the same four chemicals, using identical concentrations as for single chemical exposures, revealed combined effects that were not predicted by results for individual chemicals alone. In general, the response of exposure to this mixture led to an average loss of approximately 60% of the transcriptomic signature found for single chemical exposure. The present findings show that microarray analyses may contribute to our mechanistic understanding of single contaminant mode of action as

  8. Enhancing the Benefit of the Chemical Mixture Methodology: A Report on Methodology Testing and Potential Approaches for Improving Performance

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Xiao-Ying; Yao, Juan; He, Hua; Glantz, Clifford S.; Booth, Alexander E.

    2012-01-01

    Extensive testing shows that the current version of the Chemical Mixture Methodology (CMM) is meeting its intended mission to provide conservative estimates of the health effects from exposure to airborne chemical mixtures. However, the current version of the CMM could benefit from several enhancements that are designed to improve its application of Health Code Numbers (HCNs) and employ weighting factors to reduce over conservatism.

  9. Adaptive stress response pathways induced by environmental mixtures of bioaccumulative chemicals in dugongs.

    Science.gov (United States)

    Jin, Ling; Gaus, Caroline; Escher, Beate I

    2015-06-02

    To address the poorly understood mixture effects of chemicals in the marine mammal dugong, we coupled equilibrium-based passive sampling in blubber to a range of in vitro bioassays for screening mixtures of bioaccumulative chemicals. The modes of action included early effect indicators along important toxicity pathways, such as induction of xenobiotic metabolism, and some integrative indicators downstream of the molecular initiating event, such as adaptive stress responses. Activation of aryl hydrocarbon receptor (AhR) and Nrf2-mediated oxidative stress response were found to be the most prominent effects, while the p53-mediated DNA damage response and NF-κB-mediated response to inflammation were not significantly affected. Although polychlorinated dibenzo-p-dioxins (PCDDs) quantified in the samples accounted for the majority of AhR-mediated activity, PCDDs explained less than 5% of the total oxidative stress response, despite their known ability to activate this pathway. Altered oxidative stress response was observed with both individual chemicals and blubber extracts subject to metabolic activation by rat liver S9 fraction. Metabolic activation resulted in both enhanced and reduced toxicity, suggesting the relevance and utility of incorporating metabolic enzymes into in vitro bioassays. Our approach provides a first insight into the burden of toxicologically relevant bioaccumulative chemical mixtures in dugongs and can be applied to lipid tissue of other wildlife species.

  10. Chemical mixtures and environmental effects: a pilot study to assess ecological exposure and effects in streams

    Science.gov (United States)

    Buxton, Herbert T.; Reilly, Timothy J.; Kuivila, Kathryn M.; Kolpin, Dana W.; Bradley, Paul M.; Villeneuve, Daniel L.; Mills, Marc A.

    2015-01-01

    Assessment and management of the risks of exposure to complex chemical mixtures in streams are priorities for human and environmental health organizations around the world. The current lack of information on the composition and variability of environmental mixtures and a limited understanding of their combined effects are fundamental obstacles to timely identification and prevention of adverse human and ecological effects of exposure. This report describes the design of a field-based study of the composition and biological activity of chemical mixtures in U.S. stream waters affected by a wide range of human activities and contaminant sources. The study is a collaborative effort by the U.S. Geological Survey and the U.S. Environmental Protection Agency. Scientists sampled 38 streams spanning 24 States and Puerto Rico. Thirty-four of the sites were located in watersheds impacted by multiple contaminant sources, including industrial and municipal wastewater discharges, crop and animal agricultural runoff, urban runoff, and other point and nonpoint contaminant sources. The remaining four sites were minimally development reference watersheds. All samples underwent comprehensive chemical and biological characterization, including sensitive and specific direct analysis for over 700 dissolved organic and inorganic chemicals and field parameters, identification of unknown contaminants (environmental diagnostics), and a variety of bioassays to evaluate biological activity and toxicity.

  11. Quantification of chemical mixture interactions modulating dermal absorption using a multiple membrane fiber array.

    Science.gov (United States)

    Baynes, Ronald E; Xia, Xin Rui; Imran, Mudassar; Riviere, Jim E

    2008-03-01

    Dermal exposures to chemical mixtures can potentially increase or decrease systemic bioavailability of toxicants in the mixture. Changes in dermal permeability can be attributed to changes in physicochemical interactions between the mixture, the skin, and the solute of interest. These physicochemical interactions can be described as changes in system coefficients associated with molecular descriptors described by Abraham's linear solvation energy relationship (LSER). This study evaluated the effects of chemical mixtures containing either a solvent (ethanol) or a surfactant (sodium lauryl sulfate, SLS) on solute permeability and partitioning by quantifying changes in system coefficients in skin and a three-membrane-coated fiber (MCF) system, respectively. Regression analysis demonstrated that changes in system coefficients in skin were strongly correlated ( R2 = 0.89-0.98) to changes in system coefficients in the three-membrane MCF array with mixtures containing either 1% SLS or 50% ethanol. The PDMS fiber appeared to play a significant role (R2 = 0.84-0.85) in the MCF array in predicting changes in solute permeability, while the WAX fiber appeared to contribute less (R2 = 0.59-0.77) to the array than the other two fibers. On the basis of changes in system coefficients that are part of a LSER, these experiments were able to link physicochemical interactions in the MCF with those interactions in skin when either system is exposed to 1% SLS or 50% ethanol. These experiments further demonstrated the utility of a MCF array to adequately predict changes in dermal permeability when skin is exposed to mixtures containing either a surfactant or a solvent and provide some insight into the nature of the physiochemical interactions that modulate dermal absorptions.

  12. Gene expression profiles in rainbow trout, Onchorynchus mykiss, exposed to a simple chemical mixture.

    Science.gov (United States)

    Hook, Sharon E; Skillman, Ann D; Gopalan, Banu; Small, Jack A; Schultz, Irvin R

    2008-03-01

    Among proposed uses for microarrays in environmental toxiciology is the identification of key contributors to toxicity within a mixture. However, it remains uncertain whether the transcriptomic profiles resulting from exposure to a mixture have patterns of altered gene expression that contain identifiable contributions from each toxicant component. We exposed isogenic rainbow trout Onchorynchus mykiss, to sublethal levels of ethynylestradiol, 2,2,4,4-tetrabromodiphenyl ether, and chromium VI or to a mixture of all three toxicants Fluorescently labeled complementary DNA (cDNA) were generated and hybridized against a commercially available Salmonid array spotted with 16,000 cDNAs. Data were analyzed using analysis of variance (p<0.05) with a Benjamani-Hochberg multiple test correction (Genespring [Agilent] software package) to identify up and downregulated genes. Gene clustering patterns that can be used as "expression signatures" were determined using hierarchical cluster analysis. The gene ontology terms associated with significantly altered genes were also used to identify functional groups that were associated with toxicant exposure. Cross-ontological analytics approach was used to assign functional annotations to genes with "unknown" function. Our analysis indicates that transcriptomic profiles resulting from the mixture exposure resemble those of the individual contaminant exposures, but are not a simple additive list. However, patterns of altered genes representative of each component of the mixture are clearly discernible, and the functional classes of genes altered represent the individual components of the mixture. These findings indicate that the use of microarrays to identify transcriptomic profiles may aid in the identification of key stressors within a chemical mixture, ultimately improving environmental assessment.

  13. Toxicity of a hazardous chemical mixture in the planarian, Dugesia dorotocephala

    Energy Technology Data Exchange (ETDEWEB)

    Ramsdell, H.S.; Matthews, C.M. [Colorado State Univ., Ft. Collins, CO (United States)

    1995-12-31

    The responses of the planarian, Dugesia dorotocephala to toxic chemical mixtures representative of water contaminants associated with hazardous waste sites have been studied in laboratory experiments. These free-living flatworms are readily maintained under laboratory conditions and are a useful invertebrate model for toxicology studies. Their widespread occurrence also makes them potentially useful for environmental studies. Mature asexual Dugesia dorotocephala were exposed for 14 days to mixtures of seven contaminants frequently detected in water at hazardous waste sites. The complete 1X mixture contained both metals (As, 3.1 ppm; Cr, 0.7 ppm; Pb, 3.7 ppm) and organics (chloroform, 1.5 ppm; benzene, 5.0 ppm; phenol, 3.4 ppm; trichloroethylene, 3.8 ppm). Groups of planaria were treated with the complete mixture at 0.1X, 1X and 10X concentrations. Additional groups were exposed to the metals-only or organics-only submixtures, also at 0.1X, 1X and 10X concentrations. Treatment solutions were renewed daily. Suppression of fissioning was observed in all of the 1X and 10X treatment groups. Significant mortality occurred only in the 10X complete and 1 0X metals-only treatments. It appears that the toxic effects of the complete mixture are primarily associated with the metal components.

  14. Viscous-shock-layer solutions for turbulent flow of radiating gas mixtures in chemical equilibrium

    Science.gov (United States)

    Anderson, E. C.; Moss, J. N.

    1975-01-01

    The viscous-shock-layer equations for hypersonic laminar and turbulent flows of radiating or nonradiating gas mixtures in chemical equilibrium are presented for two-dimensional and axially-symmetric flow fields. Solutions were obtained using an implicit finite-difference scheme and results are presented for hypersonic flow over spherically-blunted cone configurations at freestream conditions representative of entry into the atmosphere of Venus. These data are compared with solutions obtained using other methods of analysis.

  15. Viscous shock layer solutions for turbulent flow of radiating gas mixtures in chemical equilibrium

    Science.gov (United States)

    Anderson, E. C.; Moss, J. N.

    1975-01-01

    The viscous shock layer equations for hypersonic laminar and turbulent flows of radiating or nonradiating gas mixtures in chemical equilibrium are presented for two-dimensional and axially symmetric flow fields. Solutions are obtained using an implicit finite difference scheme and results are presented for hypersonic flow over spherically blunted cone configurations at free stream conditions representative of entry into the atmosphere of Venus. These data are compared with solutions obtained using other methods of analysis.

  16. p53 induction and cell viability modulation by genotoxic individual chemicals and mixtures.

    Science.gov (United States)

    Di Paolo, Carolina; Müller, Yvonne; Thalmann, Beat; Hollert, Henner; Seiler, Thomas-Benjamin

    2017-03-16

    The binding of the p53 tumor suppression protein to DNA response elements after genotoxic stress can be quantified by cell-based reporter gene assays as a DNA damage endpoint. Currently, bioassay evaluation of environmental samples requires further knowledge on p53 induction by chemical mixtures and on cytotoxicity interference with p53 induction analysis for proper interpretation of results. We investigated the effects of genotoxic pharmaceuticals (actinomycin D, cyclophosphamide) and nitroaromatic compounds (4-nitroquinoline 1-oxide, 3-nitrobenzanthrone) on p53 induction and cell viability using a reporter gene and a colorimetric assay, respectively. Individual exposures were conducted in the absence or presence of metabolic activation system, while binary and tertiary mixtures were tested in its absence only. Cell viability reduction tended to present direct correlation with p53 induction, and induction peaks occurred mainly at chemical concentrations causing cell viability below 80%. Mixtures presented in general good agreement between predicted and measured p53 induction factors at lower concentrations, while higher chemical concentrations gave lower values than expected. Cytotoxicity evaluation supported the selection of concentration ranges for the p53 assay and the interpretation of its results. The often used 80% viability threshold as a basis to select the maximum test concentration for cell-based assays was not adequate for p53 induction assessment. Instead, concentrations causing up to 50% cell viability reduction should be evaluated in order to identify the lowest observed effect concentration and peak values following meaningful p53 induction.

  17. Human toxicology of chemical mixtures toxic consequences beyond the impact of one-component product and environmental exposures

    CERN Document Server

    Zeliger, Harold I

    2011-01-01

    In this important reference work, Zeliger catalogs the known effects of chemical mixtures on the human body and also proposes a framework for understanding and predicting their actions in terms of lipophile (fat soluble)/hydrophile (water soluble) interactions. The author's focus is on illnesses that ensue following exposures to mixtures of chemicals that cannot be attributed to any one component of the mixture. In the first part the mechanisms of chemical absorption at a molecular and macromolecular level are explained, as well as the body's methods of defending itself against xenobiotic intrusion. Part II examines the sources of the chemicals discussed, looking at air and water pollution, food additives, pharmaceuticals, etc. Part III, which includes numerous case studies, examines specific effects of particular mixtures on particular body systems and organs and presents a theoretical framework for predicting what the effects of uncharacterized mixtures might be. Part IV covers regulatory requirements and t...

  18. The synergistic toxicity of the multiple chemical mixtures: implications for risk assessment in the terrestrial environment.

    Science.gov (United States)

    Chen, Chen; Wang, Yanhua; Qian, Yongzhong; Zhao, Xueping; Wang, Qiang

    2015-04-01

    The combined toxicity of five insecticides (chlorpyrifos, avermectin, imidacloprid, λ-cyhalothrin, and phoxim), two herbicides (atrazine and butachlor) and a heavy metal (cadmium) has been examined with the earthworm acute toxicity test. Toxicological interactions of these chemicals in four, five, six, seven, and eight-component mixtures were studied using the combination-index (CI) equation method. In four-component and five-component mixtures, the synergistic effects predominated at lower effect levels, while the patterns of interactions found in six, seven, and eight-component mixtures displayed synergism. The λ-CY+IMI+BUT+ATR+CPF+PHO combination displayed the most strongly synergistic interaction, with CI values ranging from 0.09 to 0.15. The nature of the interaction changes with the effect level and the relevance of synergistic effects increase with the complexity of the mixture. The CI method was compared with the classical models of concentration addition (CA) and independent action (IA) and we found that the CI method could accurately predict the combined toxicity. The predicted synergism resulted from co-existence of the pesticides and the heavy metal especially at low effect levels may have important implications in risk assessment for the real terrestrial environment.

  19. Cellular RNA is chemically modified by exposure to air pollution mixtures.

    Science.gov (United States)

    Baldridge, Kevin C; Zavala, Jose; Surratt, Jason; Sexton, Kenneth G; Contreras, Lydia M

    2015-01-01

    RNAs are more susceptible to modifications than DNA, and chemical modifications in RNA have an effect on their structure and function. This study aimed to characterize chemical effects on total RNA in human A549 lung cells after exposure to elevated levels of major secondary air pollutants commonly found in urban locations, including ozone (O3), acrolein (ACR) and methacrolein (MACR). Enzyme-linked immunosorbent assays (ELISA) were used to measure levels of interleukin (IL)-8 in the growth media and 8-oxoguanine (8OG) levels in total cellular RNA, and lactate dehydrogenase (LDH) in the growth media was measured by a coupled enzymatic assay. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to measure levels of microRNA 10b (miR-10b). The study found that 1-h exposure to all tested pollutant mixtures consistently caused significant increases in the levels of 8OG in total RNA. In the case of 4 ppm O3 exposures, measured levels of IL-8, LDH and miR-10b each showed consistent trends between two independent trials, but varied among these three targets. After 1-h exposures to an ACR+MACR mixture, measured levels of IL-8, LDH and miR-10b showed variable results. For mixtures of O3+ACR+MACR, IL-8 measurements showed no change; miR-10b and LDH showed variable results. The results indicate that short-term high-concentration exposures to air pollution can cause RNA chemical modifications. Chemical modifications in RNAs could represent more consistent markers of cellular stress relative to other inflammation markers, such as IL-8 and LDH, and provide a new biomarker endpoint for mechanistic studies in toxicity of air pollution exposure.

  20. Directed transport in a ratchet with internal and chemical freedoms

    Energy Technology Data Exchange (ETDEWEB)

    Dittrich, T., E-mail: tdittrich@unal.edu.co [Departamento de Fisica, Universidad Nacional de Colombia, Bogota D.C. (Colombia); CeiBA-Complejidad, Bogota D.C. (Colombia); Naranjo, N.A. [Departamento de Fisica, Universidad Nacional de Colombia, Bogota D.C. (Colombia); CeiBA-Complejidad, Bogota D.C. (Colombia)

    2010-10-05

    Graphical abstract: Directed currents in a ratchet including a chemical freedom that provides energy input and an internal freedom modeled as a functional mode of a motor molecule show a direct relation to the structure of the underlying attaractor, limit cycle or chaotic, as reflected in their dependence on the coupling between external and chemical degrees of freedom. - Abstract: We consider mechanisms of directed current in a ratchet model comprising, besides the external freedom where transport occurs, a chemical freedom that replaces the familiar external driving by an autonomous dynamics providing energy input, and an internal freedom representing a functional mode of a motor molecule. The dependence of the current on various parameters is studied in numerical simulations of our model. In particular, we point out the role of the internal freedom as a buffer between energy input and output of mechanical work that allows a temporary storage of injected energy and can contribute to the efficiency of current generation.

  1. Summer 2012 Testing and Analysis of the Chemical Mixture Methodology -- Part I

    Energy Technology Data Exchange (ETDEWEB)

    Glantz, Clifford S.; Yu, Xiao-Ying; Coggin, Rebekah L.; Ponder, Lashaundra A.; Booth, Alexander E.; Petrocchi, Achille J.; Horn, Sarah M.; Yao, Juan

    2012-07-01

    This report presents the key findings made by the Chemical Mixture Methodology (CMM) project team during the first stage of their summer 2012 testing and analysis of the CMM. The study focused on answering the following questions: o What is the percentage of the chemicals in the CMM Rev 27 database associated with each Health Code Number (HCN)? How does this result influence the relative importance of acute HCNs and chronic HCNs in the CMM data set? o What is the benefit of using the HCN-based approach? Which Modes of Action and Target Organ Effects tend to be important in determining the HCN-based Hazard Index (HI) for a chemical mixture? o What are some of the potential issues associated with the current HCN-based approach? What are the opportunities for improving the performance and/or technical defensibility of the HCN-based approach? How would those improvements increase the benefit of using the HCN-based approach? o What is the Target Organ System Effect approach and how can it be used to improve upon the current HCN-based approach? How does the benefits users would derive from using the Target Organ System Approach compare to the benefits available from the current HCN-based approach?

  2. Chemical Oxidation of Complex PAH Mixtures by Base-activated Sodium Persulfate

    Science.gov (United States)

    Hauswirth, S.; Miller, C. T.

    2013-12-01

    In situ chemical oxidation (ISCO) is an attractive approach for the remediation of recalcitrant soil and groundwater contaminants. One oxidant that has received significant recent attention is sodium persulfate, which has several advantages, including a relatively long lifetime in porous media, the ability to destroy a wide-range of chemical contaminants, and a high oxidation potential. In this study, we investigated the chemical mechanisms associated with base-activated persulfate oxidation of polycyclic aromatic hydrocarbons (PAHs) and assessed the applicability of persulfate to the remediation of porous media contaminated with non-aqueous phase liquid (NAPL) PAH mixtures. Batch experiments were conducted to determine the oxidation kinetics for individual PAH compounds, synthetic PAH mixtures, and manufactured gas plant (MGP) tars. Additional experiments were conducted with added surfactants (Triton X-100, Triton X-45, and Tween 80) to increase PAH mass transfer from the NAPL to the aqueous phase, and with radical scavengers (ethanol and tert-butyl alcohol) to identify the reactive species responsible for degradation. Degradation of total PAHs in the NAPL experiments was as high as 70%. The addition of surfactant increased initial PAH degradation rates, but also greatly increased the rate of base consumption, thereby reducing the overall fraction degraded. The degradation of individual PAHs within the NAPLs varied significantly, with the masses of some compounds remaining largely unchanged. The results of the radical scavenger and single PAH experiments suggest that the observed pattern of degradation in PAH mixtures is the result of a combination of mass transfer considerations and competition for radical species.

  3. Application of the cubic-plus-association equation of state to mixtures with polar chemicals and high pressures

    DEFF Research Database (Denmark)

    Folas, Georgios; Kontogeorgis, Georgios; Michelsen, Michael Locht

    2006-01-01

    was given to low pressures and liquid-liquid equilibria. In this work, CPA is applied to two classes of mixtures containing polar chemicals for which high-pressure data are available: acetone-containing systems and dimethyl ether mixtures. They are of both scientific and industrial importance. Moreover, CPA...... is applied to high-pressure solid-liquid equilibria (SLE) for alcohol-alkane mixtures. In the case of acetone-hydrocarbon mixtures, satisfactory results are achieved if acetone is allowed to self-associate. Satisfactory high-pressure acetone-water vapor-liquid equilibrium (VLE) is obtained, comparable...

  4. Characterization of Dimethylsulfoxide / Glycerol Mixtures: A Binary Solvent System for the Study of "Friction-Dependent" Chemical Reactivity

    CERN Document Server

    Angulo, Gonzalo; Gerecke, Mario; Grampp, Günter; Jeannerat, Damien; Milkiewicz, Jadwiga; Mitrev, Yavor; Radzewicz, Czesław; Rosspeintner, Arnulf; Vauthey, Eric; Wnuk, Paweł

    2016-01-01

    The properties of binary mixtures of dimethylsulfoxide and glycerol, measured by several techniques, are reported. Special attention is given to those properties contributing or affecting chemical reactions. In this respect the investigated mixture behaves as a relatively simple solvent and it is especially well suited for studies on the influence of viscosity in chemical reactivity. This is due to the relative invariance of the dielectric properties of the mixture. However, special caution must be taken with specific solvation, as the hydrogen-bonding properties of the solvent changes with the molar fraction of glycerol.

  5. Separation of americium and curium from complex chemical and radiochemical mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Bochkarev, V.A.; Martynov, N.P.; Slivin, V.G.; Trikanov, A.E.; Fedyaeva, N.V.

    1988-11-01

    This work describes a method for separation and radiochemical purification of nanogram levels of americium and curium from complex chemical and radiochemical mixtures containing tens of milligrams of elements such as aluminum, iron, magnesium, calcium, barium, titanium, potassium, and others, microgram levels of uranium, neptunium, and plutonium, and fission products. Extraction coefficients of americium and curium from these elements are measured. The separation from the macrocomponents was carried out by extraction of americium and curium with butyric acid in the presence of sulfosalicylic acid. Uranium, neptunium, and plutonium were separated from hydrochloric acid solutions, while the rare earth elements were separated from lithium chloride solutions using a column of anion exchange resin AV-17. Alpha measurements were carried out on americium and curium deposited electrolytically on tantalum cathodes. The chemical yield of americium and curium was identical of greater than or equal to 94%, separation time approx. 8 h.

  6. Chemical Discrimination in Turbulent Gas Mixtures with MOX Sensors Validated by Gas Chromatography-Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    Jordi Fonollosa

    2014-10-01

    Full Text Available Chemical detection systems based on chemo-resistive sensors usually include a gas chamber to control the sample air flow and to minimize turbulence. However, such a kind of experimental setup does not reproduce the gas concentration fluctuations observed in natural environments and destroys the spatio-temporal information contained in gas plumes. Aiming at reproducing more realistic environments, we utilize a wind tunnel with two independent gas sources that get naturally mixed along a turbulent flow. For the first time, chemo-resistive gas sensors are exposed to dynamic gas mixtures generated with several concentration levels at the sources. Moreover, the ground truth of gas concentrations at the sensor location was estimated by means of gas chromatography-mass spectrometry. We used a support vector machine as a tool to show that chemo-resistive transduction can be utilized to reliably identify chemical components in dynamic turbulent mixtures, as long as sufficient gas concentration coverage is used. We show that in open sampling systems, training the classifiers only on high concentrations of gases produces less effective classification and that it is important to calibrate the classification method with data at low gas concentrations to achieve optimal performance.

  7. Chemical discrimination in turbulent gas mixtures with MOX sensors validated by gas chromatography-mass spectrometry.

    Science.gov (United States)

    Fonollosa, Jordi; Rodríguez-Luján, Irene; Trincavelli, Marco; Vergara, Alexander; Huerta, Ramón

    2014-10-16

    Chemical detection systems based on chemo-resistive sensors usually include a gas chamber to control the sample air flow and to minimize turbulence. However, such a kind of experimental setup does not reproduce the gas concentration fluctuations observed in natural environments and destroys the spatio-temporal information contained in gas plumes. Aiming at reproducing more realistic environments, we utilize a wind tunnel with two independent gas sources that get naturally mixed along a turbulent flow. For the first time, chemo-resistive gas sensors are exposed to dynamic gas mixtures generated with several concentration levels at the sources. Moreover, the ground truth of gas concentrations at the sensor location was estimated by means of gas chromatography-mass spectrometry. We used a support vector machine as a tool to show that chemo-resistive transduction can be utilized to reliably identify chemical components in dynamic turbulent mixtures, as long as sufficient gas concentration coverage is used. We show that in open sampling systems, training the classifiers only on high concentrations of gases produces less effective classification and that it is important to calibrate the classification method with data at low gas concentrations to achieve optimal performance.

  8. Allium-test as a tool for toxicity testing of environmental radioactive-chemical mixtures

    Science.gov (United States)

    Oudalova, A. A.; Geras’kin, S. A.; Dikareva, N. S.; Pyatkova, S. V.

    2017-01-01

    Bioassay-based approaches have been propagated to assess toxicity of unknown mixtures of environmental contaminants, but it was rarely applied in cases of chemicals with radionuclides combinations. Two Allium-test studies were performed to assess environmental impact from potential sources of combined radioactive-chemical pollution. Study sites were located at nuclear waste storage facilities in European and in Far-Eastern parts of Russia. As environmental media under impact, waters from monitor wells and nearby water bodies were tested. Concentrations of some chemicals and radionuclides in the samples collected enhanced the permitted limits. Cytogenetic and cytotoxic effects were used as biological endpoints, namely, frequency and spectrum of chromosome aberrations and mitotic abnormalities in anatelophase cells as well as mitotic activity in Allium root tips. Sample points were revealed where waters have an enhanced mutagenic potential. The findings obtained could be used to optimize monitoring system and advance decision making on management and rehabilitation of industrial sites. The Allium-test could be recommended and applied as an effective tool for toxicity testing in case of combined contamination of environmental compartments with radionuclides and chemical compounds.

  9. Directed transport in a ratchet with internal and chemical freedoms

    CERN Document Server

    Dittrich, Thomas

    2010-01-01

    We consider mechanisms of directed transport in a ratchet model comprising, besides the external freedom where transport occurs, a chemical freedom that replaces the familiar external driving by an autonomous dynamics providing energy input, and an internal freedom representing a functional mode of a motor molecule. The dependence of the current on various parameters is studied in numerical simulations of our model. In particular, we point out the role of the internal freedom as a buffer between energy input and output of mechanical work that allows a temporary storage of injected energy and can contribute to the efficiency of current generation.

  10. Conversion of Hazardous Motor Vehicle Used Tire and Polystyrene Waste Plastic Mixture into useful Chemical Products

    Directory of Open Access Journals (Sweden)

    Moinuddin Sarker

    2014-02-01

    Full Text Available Motor vehicle used tire and polystyrene waste plastic mixture into fuel recovery using thermal degradation process in laboratory batch process. Motor vehicle used tire and polystyrene waste plastic was use 75 gm by weight. Motor vehicle tire was 25 gm and polystyrene waste plastic was 50 gm. In presence of oxygen experiment was performed under laboratory fume hood. Thermal degradation temperature range was 100 - 420 oC and experiment run time was 5 hours. Product fuel density is 0.84 gm/ml and liquid fuel conversion rate was 54.93 %. Fuel was analysis by GC/MS and compounds are present aliphatic group, aromatic group, alcoholic group, oxygen content and nitrogen content.Fuel can use refinery process as a refinery feed.Keywords: Tire, polystyrene, conversion, chemical product, vehicle, hydrocarbon

  11. Quasi-chemical approach for adsorption of mixtures with non-additive lateral interactions

    Science.gov (United States)

    Pinto, O. A.; Pasinetti, P. M.; Ramirez-Pastor, A. J.

    2017-01-01

    The statistical thermodynamics of binary mixtures with non-additive lateral interactions was developed on a generalization in the spirit of the lattice-gas model and the classical quasi-chemical approximation (QCA). The traditional assumption of a strictly pairwise additive nearest-neighbors interaction is replaced by a more general one, namely that the bond linking a certain atom with any of its neighbors depends considerably on how many of them are actually present (or absent) on the sites in the first coordination shell of the atom. The total and partial adsorption isotherms are given for both attractive and repulsive lateral interactions between the adsorbed species. Interesting behaviors are observed and discussed in terms of the low-temperature phases formed in the system. Comparisons with Monte Carlo simulations are performed in order to test the validity of the theoretical model.

  12. Chemical synthesis and characterization of highly soluble conducting polyaniline in the mixtures of common solvents

    Directory of Open Access Journals (Sweden)

    Zeghioud Hichem

    2015-01-01

    Full Text Available This work presents the synthesis and characterization of soluble and conducting polyaniline PANI-PIA according to chemical polymerization route. This polymerization pathway leads to the formation of poly(itaconic acid doped polyaniline salts, which are highly soluble in a number of mixtures between organic common polar solvents and water, the solubility reaches 4 mg mL-1. The effect of synthesis parameters such as doping level on the conductivity and the study of solubility and other properties of the resulting PANI salts were also undertaken. The maximum of conductivity was found equal to 2.48×10-4 S cm-1 for fully protonated PANI-EB. In addition, various characterizations of the synthesized materials were also done with the help of viscosity measurements, UV-vis spectroscopy, XRD, FTIR and finally TGA for the thermal properties behaviour.

  13. Ignition of a lean PRF/air mixture under RCCI/SCCI conditions: Chemical aspects

    KAUST Repository

    Luong, Minh Bau

    2016-10-10

    Chemical aspects of the ignition of a primary reference fuel (PRF)/air mixture under reactivity controlled compression ignition (RCCI) and stratified charge compression ignition (SCCI) conditions are investigated by analyzing two-dimensional direct numerical simulation (DNS) data with chemical explosive mode (CEM) analysis. CEMA is adopted to provide fundamental insights into the ignition process by identifying controlling species and elementary reactions at different locations and times. It is found that at the first ignition delay, low-temperature chemistry (LTC) represented by the isomerization of alkylperoxy radical, chain branching reactions of keto-hydroperoxide, and H-atom abstraction of n-heptane is predominant for both RCCI and SCCI combustion. In addition, explosion index and participation index analyses together with conditional means on temperature verify that low-temperature heat release (LTHR) from local mixtures with relatively-high n-heptane concentration occurs more intensively in RCCI combustion than in SCCI combustion, which ultimately advances the overall RCCI combustion and distributes its heat release rate over time. It is also found that at the onset of the main combustion, high-temperature heat release (HTHR) occurs primarily in thin deflagrations where temperature, CO, and OH are found to be the most important species for the combustion. The conversion reaction of CO to CO and hydrogen chemistry are identified as important reactions for HTHR. The overall RCCI/SCCI combustion can be understood by mapping the variation of 2-D RCCI/SCCI combustion in temperature space onto the temporal evolution of 0-D ignition.

  14. Using Mode of Action to Assess Health Risks from Mixtures of Chemical/Physical Agents

    Energy Technology Data Exchange (ETDEWEB)

    Bull, Richard J.; Lei, Xingye C.; Sasser, Lyle B.

    2003-01-20

    Interactions between tumor promoters with differing mechanisms of action were examined in male B6C3F1 mice treated with mixtures of dichloroacetate (DCA), trichloroacetate (TCA), and tetrachloride (CT), each of which acts by a different mode of action. Mice were initiated by vinyl carbamate (VC), and then promoted by DCA, TCA, CT, or the pair-wised combinations of the three compounds. The effect of each treatment or treatment combination on tumor number/animal and tumor size was individually assessed at 18, 24, 30 or 36 weeks of treatment. Dose-related increases in tumor size were observed with 20 & 50 mg/kg CT, but each produced equal number of tumors at 36 weeks with the main distinction being a decrease in tumor latency at the higher dose. Overall TCA treatment produced dose-related increases in tumor number at 36 weeks of treatment. Thus, the lower doses of CT and TCA treatments apparently affected tumor size rather than number. Results with DCA were not as clear as a true maximum tumor number was not clearly observed within the experimental period. Treatment of mice receiving a high dose of TCA (2 g/L of drinking water) combined with varying doses of DCA (0.1, 0.5 and 2 g/L) produced increased numbers of tumors at 24 weeks and 36 weeks. However, at 36 weeks of treatment DCA produced a dose-related decrease in the size of tumors promoted by TCA. The low dose of TCA (0.1 g/L) decreased the number of tumors produced by a high dose of DCA, however, higher doses of TCA produced the same number as observed with DCA alone. Since these two chemicals produce lesions with differing phenotypes, the combination would have been expected to be additive with respect to number, but this was obviously not the case. These data suggest that the induction of liver cancer from mixtures of solvents may have predictable outcomes. The major conclusion is that these interactions are generally no more than additive. It was most interesting to note that additivity was only observed when

  15. A simple procedure for estimating pseudo risk ratios from exposure to non-carcinogenic chemical mixtures.

    Science.gov (United States)

    Scinicariello, Franco; Portier, Christopher

    2016-03-01

    Non-cancer risk assessment traditionally assumes a threshold of effect, below which there is a negligible risk of an adverse effect. The Agency for Toxic Substances and Disease Registry derives health-based guidance values known as Minimal Risk Levels (MRLs) as estimates of the toxicity threshold for non-carcinogens. Although the definition of an MRL, as well as EPA reference dose values (RfD and RfC), is a level that corresponds to "negligible risk," they represent daily exposure doses or concentrations, not risks. We present a new approach to calculate the risk at exposure to specific doses for chemical mixtures, the assumption in this approach is to assign de minimis risk at the MRL. The assigned risk enables the estimation of parameters in an exponential model, providing a complete dose-response curve for each compound from the chosen point of departure to zero. We estimated parameters for 27 chemicals. The value of k, which determines the shape of the dose-response curve, was moderately insensitive to the choice of the risk at the MRL. The approach presented here allows for the calculation of a risk from a single substance or the combined risk from multiple chemical exposures in a community. The methodology is applicable from point of departure data derived from quantal data, such as data from benchmark dose analyses or from data that can be transformed into probabilities, such as lowest-observed-adverse-effect level. The individual risks are used to calculate risk ratios that can facilitate comparison and cost-benefit analyses of environmental contamination control strategies.

  16. [International Chemical Safety Cards: information source on hazards caused by chemical substances].

    Science.gov (United States)

    Pakulska, Daria; Czerczak, Sławomir

    2007-01-01

    International Chemical Safety Cards (ICSC) are produced by the International Programme on Chemical Safety (IPCS) in collaboration with the European Commission and various IPCS-participating institutions in different countries. ICSCs disseminate essential information on chemicals to promote their safe production, transport and use. Application of standard terminology along with relevant criteria facilitates the comparison of risk related to different chemicals, which makes the cards a successful hazard-communication tool. Translation of the cards into various languages all over the world reflects the range of their growing use. A multi-stage compilation of information contained in ICSCs, based on the most up-to-date world literature and professional databases, assures its reliability. Their concise form makes them easy in everyday use as a source of information on chemical safety. The range of information contained in ICSCs corresponds to that provided by Material Safety Data Sheets (MSDS), however, the former are more concise and simpler. Although ICSCs have no legal status they may complement a 16-point MSDSs and help in the implementation of labeling and classification of chemicals according to the Globally Harmonized System.

  17. Biological and chemical reactivity and phosphorus forms of buffalo manure compost, vermicompost and their mixture with biochar.

    Science.gov (United States)

    Ngo, Phuong-Thi; Rumpel, Cornelia; Ngo, Quoc-Anh; Alexis, Marie; Velásquez Vargas, Gabriela; Mora Gil, Maria de la Luz; Dang, Dinh-Kim; Jouquet, Pascal

    2013-11-01

    This study characterized the carbon and phosphorus composition of buffalo manure, its compost and vermicompost and investigated if presence of bamboo biochar has an effect on their chemical and biological reactivity. The four substrates were characterized for chemical and biochemical composition and P forms. The biological stability of the four substrates and their mixtures were determined during an incubation experiment. Their chemical reactivity was analyzed after acid dichromate oxidation. Biological reactivity of these substrates was related to their soluble organic matter content, which decreased in the order buffalo manure>compost>vermicompost. Phosphorus was labile in all organic substrates and composting transformed organic P into plant available P. The presence of biochar led to a protection of organic matter against chemical oxidation and changed their susceptibility to biological degradation, suggesting that biochar could increase the carbon sequestration potential of compost, vermicompost and manure, when applied in mixture.

  18. Analysis of Environmental Chemical Mixtures and Non-Hodgkin Lymphoma Risk in the NCI-SEER NHL Study

    Science.gov (United States)

    Czarnota, Jenna; Gennings, Chris; Colt, Joanne S.; De Roos, Anneclaire J.; Cerhan, James R.; Severson, Richard K.; Hartge, Patricia; Ward, Mary H.

    2015-01-01

    Background There are several suspected environmental risk factors for non-Hodgkin lymphoma (NHL). The associations between NHL and environmental chemical exposures have typically been evaluated for individual chemicals (i.e., one-by-one). Objectives We determined the association between a mixture of 27 correlated chemicals measured in house dust and NHL risk. Methods We conducted a population-based case–control study of NHL in four National Cancer Institute–Surveillance, Epidemiology, and End Results centers—Detroit, Michigan; Iowa; Los Angeles County, California; and Seattle, Washington—from 1998 to 2000. We used weighted quantile sum (WQS) regression to model the association of a mixture of chemicals and risk of NHL. The WQS index was a sum of weighted quartiles for 5 polychlorinated biphenyls (PCBs), 7 polycyclic aromatic hydrocarbons (PAHs), and 15 pesticides. We estimated chemical mixture weights and effects for study sites combined and for each site individually, and also for histologic subtypes of NHL. Results The WQS index was statistically significantly associated with NHL overall [odds ratio (OR) = 1.30; 95% CI: 1.08, 1.56; p = 0.006; for one quartile increase] and in the study sites of Detroit (OR = 1.71; 95% CI: 1.02, 2.92; p = 0.045), Los Angeles (OR = 1.44; 95% CI: 1.00, 2.08; p = 0.049), and Iowa (OR = 1.76; 95% CI: 1.23, 2.53; p = 0.002). The index was marginally statistically significant in Seattle (OR = 1.39; 95% CI: 0.97, 1.99; p = 0.071). The most highly weighted chemicals for predicting risk overall were PCB congener 180 and propoxur. Highly weighted chemicals varied by study site; PCBs were more highly weighted in Detroit, and pesticides were more highly weighted in Iowa. Conclusions An index of chemical mixtures was significantly associated with NHL. Our results show the importance of evaluating chemical mixtures when studying cancer risk. Citation Czarnota J, Gennings C, Colt JS, De Roos AJ, Cerhan JR, Severson RK, Hartge P, Ward MH

  19. Juvenile Male Rats Exposed to a Low-Dose Mixture of Twenty-Seven Environmental Chemicals Display Adverse Health Effects

    DEFF Research Database (Denmark)

    Hadrup, Niels; Svingen, Terje; Egebjerg, Karen Mandrup;

    2016-01-01

    of 27 chemicals administered orally to juvenile male rats for three months could leave a pathophysiological footprint. The mixture contained metals, perfluorinated compounds, PCB, dioxins, pesticides, heterocyclic amines, phthalate, PAHs and others, with a combined dose of 0.16 (Low dose), 0.47 (Mid...

  20. Subtleties of human exposure and response to chemical mixtures from spills.

    Science.gov (United States)

    Phetxumphou, Katherine; Dietrich, Andrea M; Shanaiah, Narasimhamurthy; Smiley, Elizabeth; Gallagher, Daniel L

    2016-07-01

    Worldwide, chemical spills degrade drinking water quality and threaten human health through ingestion and inhalation. Spills are often mixtures of chemicals; thus, understanding the interaction of chemical and biological properties of the major and minor components is critical to assessing human exposure. The crude (4-methylcyclohexyl)methanol (MCHM) spill provides an opportunity to assess such subtleties. This research determined the relative amounts, volatilization, and biological odor properties of minor components cis- and trans-methyl-4-methylcyclohexanecarboxylate (MMCHC) isomers and major components cis- and trans-4-MCHM, then compared properties and human exposure differences among them. (1)H nuclear magnetic resonance and chromatography revealed that the minor MMCHC isomers were about 1% of the major MCHM isomers. At typical showering temperature of 40 °C, Henry's law constants were 1.50 × 10(-2) and 2.23 × 10(-2) for cis- and trans-MMCHC, respectively, which is 20-50 fold higher than for 4-MCHM isomers. The odor thresholds were 1.83 and 0.02 ppb-v air for cis- and trans-MMCHC, which were both described as predominantly sweet. These data are compared to the higher 120 ppb-v air and 0.06 ppb-v odor thresholds for cis- and trans-4-MCHM, for which the trans-isomer had a dominant licorice descriptor. Application of a shower model demonstrated that while MMCHC isomers are only about 1% of the MCHM isomers, during showering, the MMCHC isomers are 13.8% by volume (16.3% by mass) because of their higher volatility. Trans-4-MCHM contributed about 82% of the odor because of higher volatility and lower odor threshold, trans-MMCHC, which represents 0.3% of the mass, contributed 18% of the odor. This study, with its unique human sensory component to assess exposure, reaffirmed that hazard assessment must not be based solely on relative concentration, but also consider the chemical fate, transport, and biological properties to determine the actual levels of

  1. International comparison of criteria for evaluating sensitization of PRTR-designated chemical substances.

    Science.gov (United States)

    Murakami, Tomoe; Oyama, Tsunehiro; Isse, Toyohi; Ogawa, Masanori; Sugie, Takuya; Kawamoto, Toshihiro

    2007-03-01

    In this study, we aim to compare the criteria for sensitizers among national organizations in various countries and international organizations, and to specify whether each Pollutant Release and Transfer Register (PRTR)-designated chemical substance is a sensitizer by each organization. The definition of sensitizing chemicals and the designation of respective sensitizers according to the PRTR law, Japan Society for Occupational Health (JSOH), American Conference of Governmental Industrial Hygienists (ACGIH), European Union (EU), and Deutsche Forschungsgemeinshaft (DFG) were studied. Of the 435 PRTR-designated chemical substances, 15 are listed as sensitizers according to the PRTR law, 16 as sensitizers of the airway and 21 as sensitizers of the skin by JSOH, 12 as sensitizers (no discrimination) by ACGIH, 19 (airway) and 85 (skin) by EU, and 15 (airway) and 43 (skin) by DFG. Only 9 substances were designated as sensitizers by all these organizations. The variation in the designation of sensitizers is accounted for by the differences in the classification criteria and grouping of chemical substances. JSOH limits the definition of sensitizers to substances that induce allergic reactions in humans and uses only human data. Other organizations utilize not only human evidence but also appropriate animal tests. In addition, EU designates an isocyanate as a sensitizer except those for which there is evidence showing that they do not cause respiratory sensitivity. The worldwide enforcement of the globally harmonized system (GHS) of classification and labeling of chemicals could promote not only the consistent designation of sensitizers among national and international organizations, but also the development of testing guidelines and classification criteria for mixtures.

  2. Probabilistic Health Risk Assessment of Chemical Mixtures: Importance of Travel Times and Connectivity

    Science.gov (United States)

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

    2014-05-01

    Subsurface contamination cases giving rise to groundwater pollutions are extensively found in all industrialized countries. Under this pressure, risk assessment methods play an important role in population protection by (1) quantifying the potential impact on human health of an aquifer contamination and (2) helping and driving decisions of groundwater-resource managers. Many reactive components such as chlorinated solvents or nitrates potentially experience attenuation processes under common geochemical conditions. This represents an attractive and extensively used remediation solution but leads often to the production of by-products before to reach a harmless chemical form. This renders mixtures of contaminants a common issue for groundwater resources managers. In this case, the threat posed by these contaminants to human health at a given sensitive location greatly depends on the competition between reactive and advective-dispersive characteristic times. However, hydraulic properties of the aquifer are known to be spatially variable, which can lead to the formation of preferential flow channels and fast contamination pathways. Therefore, the uncertainty on the spatial distribution of the aquifer properties controlling the plume travel time may then play a particular role in the human health risk assessment of chemical mixtures. We investigate here the risk related to a multispecies system in response to different degrees of heterogeneity of the hydraulic conductivity (K or Y =ln(K)). This work focuses on a Perchloroethylene (PCE) contamination problem followed by the sequential first-order production/biodegradation of its daughter species Trichloroethylene (TCE), Dichloroethylene (DCE) and Vinyl Chlorine (VC). For this specific case, VC is known to be a highly toxic contaminant. By performing numerical experiments, we evaluate transport through three-dimensional mildly (σY 2=1.0) and highly (σY 2=4.0) heterogeneous aquifers. Uncertainty on the hydraulic

  3. Stabilization of heavy oil-water emulsions using a bio/chemical emulsifier mixture

    Energy Technology Data Exchange (ETDEWEB)

    Farahbakhsh, A.; Taghizadeh, M.; Movagharnejad, K. [Chemical Engineering Department, Babol University of Technology, Babol (Iran, Islamic Republic of); Yakhchali, B. [National Institute of Genetic Engineering and Biotechnology, Tehran (Iran, Islamic Republic of)

    2011-11-15

    In this study, the viscosity reduction of heavy oil has been investigated through the formation of oil-water emulsion using a bio/chemical emulsifier mixture. Four bioemulsifiers from indigenous Rhodococcus ergthropolis and Bacillus licheniformis strains were used to stabilize a highly-viscous oil-in-water emulsion. The Taguchi method with an L{sub 9} orthogonal array design was used to investigate the effect of various control factors on the formation of the oil/water emulsions. An emulsion with lowest viscosity was formed using ACO4 strain. The substantial stability of the oil-in-water emulsion allows the heavy oil to be transported practically over long distances or remain stationary for a considerable period of time prior to utilization. As the result of Taguchi analysis, the temperature and concentration of the emulsifier had a significant influence on viscosity reduction of the emulsion. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Atmospheric pressure chemical ionization Fourier transform ion cyclotron resonance mass spectrometry for complex thiophenic mixture analysis

    KAUST Repository

    Hourani, Nadim

    2013-10-01

    Rationale Polycyclic aromatic sulfur heterocycles (PASHs) are detrimental species for refining processes in petroleum industry. Current mass spectrometric Methods that determine their composition are often preceded by derivatization and dopant addition approaches. Different ionization Methods have different impact on the molecular assignment of complex PASHs. The analysis of such species under atmospheric pressure chemical ionization (APCI) is still considered limited due to uncontrolled ion generation with low- and high-mass PASHs. Methods The ionization behavior of a model mixture of five selected PASH standards was investigated using an APCI source with nitrogen as the reagent gas. A complex thiophenic fraction was separated from a vacuum gas oil (VGO) and injected using the same method. The samples were analyzed using Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS). RESULTS PASH model analytes were successfully ionized and mainly [M + H]+ ions were produced. The same ionization pattern was observed for the real thiophenic sample. It was found that S1 class species were the major sulfur-containing species found in the VGO sample. These species indicated the presence of alkylated benzothiophenic (BT), dibenzothiophenic (DBT) and benzonaphthothiophenic (BNT) series that were detected by APCI-FTICR MS. CONCLUSIONS This study provides an established APCI-FTICR MS method for the analysis of complex PASHs. PASHs were detected without using any derivatization and without fragmentation. The method can be used for the analysis of S-containing crude oil samples. © 2013 John Wiley & Sons, Ltd.

  5. Physico-chemical properties of chars obtained in the co-pyrolysis of waste mixtures.

    Science.gov (United States)

    Bernardo, M; Lapa, N; Gonçalves, M; Mendes, B; Pinto, F; Fonseca, I; Lopes, H

    2012-06-15

    The present work aims to perform a multistep upgrading of chars obtained in the co-pyrolysis of PE, PP and PS plastic wastes, pine biomass and used tires. The quality of the upgraded chars was evaluated by measuring some of their physico-chemical properties in order to assess their valorisation as adsorbents' precursors. The crude chars were submitted to a sequential solvent extraction with organic solvents of increasing polarity (hexane, mixture 1:1 v/v hexane:acetone and acetone) followed by an acidic demineralization procedure with 1M HCl solution. The results obtained showed that the upgrading treatment allow the recovery of 63-81% of the pyrolysis oils trapped in the crude chars and a reduction in the char's ash content in the range of 64-86%. The textural and adsorption properties of the upgraded chars were evaluated and the results indicate that the chars are mainly mesoporous and macroporous materials, with adsorption capacities in the range of 3.59-22.2 mg/g for the methylene blue dye. The upgrading treatment allowed to obtain carbonaceous materials with quality to be reused as adsorbents or as precursors for activated carbon.

  6. Model-based experimental design for assessing effects of mixtures of chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Baas, Jan, E-mail: jan.baas@falw.vu.n [Vrije Universiteit of Amsterdam, Dept of Theoretical Biology, De Boelelaan 1085, 1081 HV Amsterdam (Netherlands); Stefanowicz, Anna M., E-mail: anna.stefanowicz@uj.edu.p [Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, 30-387 Krakow (Poland); Klimek, Beata, E-mail: beata.klimek@uj.edu.p [Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, 30-387 Krakow (Poland); Laskowski, Ryszard, E-mail: ryszard.laskowski@uj.edu.p [Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, 30-387 Krakow (Poland); Kooijman, Sebastiaan A.L.M., E-mail: bas@bio.vu.n [Vrije Universiteit of Amsterdam, Dept of Theoretical Biology, De Boelelaan 1085, 1081 HV Amsterdam (Netherlands)

    2010-01-15

    We exposed flour beetles (Tribolium castaneum) to a mixture of four poly aromatic hydrocarbons (PAHs). The experimental setup was chosen such that the emphasis was on assessing partial effects. We interpreted the effects of the mixture by a process-based model, with a threshold concentration for effects on survival. The behavior of the threshold concentration was one of the key features of this research. We showed that the threshold concentration is shared by toxicants with the same mode of action, which gives a mechanistic explanation for the observation that toxic effects in mixtures may occur in concentration ranges where the individual components do not show effects. Our approach gives reliable predictions of partial effects on survival and allows for a reduction of experimental effort in assessing effects of mixtures, extrapolations to other mixtures, other points in time, or in a wider perspective to other organisms. - We show a mechanistic approach to assess effects of mixtures in low concentrations.

  7. Physical-chemical characteristics of an eco-friendly binder using ternary mixture of industrial wastes

    Directory of Open Access Journals (Sweden)

    Nguyen, Hoang-Anh

    2015-09-01

    Full Text Available This study explores the physical-chemical characteristics of paste and mortar with an eco-friendly binder named as SFC cement, produced by a ternary mixture of industrial waste materials of ground granulated blast furnace slag (S, Class F fly ash (FFA, and circulating fluidized bed combustion fly ash (CFA. To trigger the hydration, the CFA, which acted as an alkaline-sulfate activator, was added to the blended mixture of slag and FFA. The water to binder ratio (W/B, curing regime, and FFA addition significantly affected the engineering performances and shrinkage/expansion of the SFC pastes and mortars. The SFC mortars had higher workability than that of ordinary Portland cement (OPC. With similar workability, the SFC mortars had compressive strengths and expansions comparable to OPC mortars. The main hydration products of the hardened SFC cement were ettringite (AFt and C-S-H/C-A-S-H. The transformation of the AFt to the monosulfates was observed as the hydration time increased.Este trabajo estudia las características fisicoquímicas de pastas y morteros con un ligante eco-amigable llamado cemento SFC, producido por una mezcla ternaria de materiales a partir de residuos industriales tales como escorias granuladas de alto horno (S, ceniza volante clase F (FFA, y cenizas volantes de combustión en lecho fluidizado circulante (CFA. Para desencadenar la hidratación, el CFA que actuó como un activador alcalino-sulfato se añadió a la mezcla combinada de escoria y FFA. La relación de agua/ligante (W/B, el tipo de curado, y la adición de FFA afectaron significativamente a las prestaciones mecánicas así como a la retracción/expansión de pastas y morteros de SFC. Los morteros SFC presentaron una trabajabilidad mayor que los correspondientes de cemento de Portland (OPC. Con una trabajabilidad similar, los morteros SFC presentaron resistencias mecánicas y expansión comparables a los morteros de OPC. Los principales productos de hidratación del

  8. Genotoxic and hematological effects in children exposed to a chemical mixture in a petrochemical area in Mexico.

    Science.gov (United States)

    Pelallo-Martínez, Nadia Azenet; Batres-Esquivel, Lilia; Carrizales-Yáñez, Leticia; Díaz-Barriga, Fernando Martínez

    2014-07-01

    Children living in Coatzacoalcos, Veracruz, and in nearby surrounding areas are exposed to a mixture of pollutants from different sources. Previous studies in the area have reported genotoxic and haematotoxic compounds, such as lead (Pb), benzene, toluene, and polycyclic aromatic hydrocarbons (PAHs), in environmental and biological samples. The final toxic effects of these compounds are unknown because the toxic behaviour of each compound is modified when in a complex mixture. This is the first study on the exposure and effect of chemical mixtures on children who live near a petrochemical area. The aim of this study was to evaluate genotoxicity and haematological effects in children environmentally exposed to such mixtures and to determine whether the final effect was modified by the composition of the mixture composition. Biomarkers of exposure to Pb, benzene, toluene, and PAHs were quantified in urine and blood samples of 102 children. DNA damage was evaluated using comet assay, and haematological parameters were determined. Our results show that Pb and toluene did not surpass the exposure guidelines; the exposure was similar in all three localities (Allenede, Mundo Nuevo, and López Mateos). In contrast, exposure to PAHs was observed at three levels of exposure: low, medium, and high. The most severe effects of these mixtures were strictly related to coexposure to high levels of PAHs.

  9. Theory and simulations for hard-disk models of binary mixtures of molecules with internal degrees of freedom

    DEFF Research Database (Denmark)

    Fraser, Diane P.; Zuckermann, Martin J.; Mouritsen, Ole G.

    1991-01-01

    by the method in the case of a binary mixture, and results are presented for varying disk-size ratios and degeneracies. The results are also compared with the predictions of the extended scaled-particle theory. Applications of the model are discussed in relation to lipid monolayers spread on air......A two-dimensional Monte Carlo simulation method based on the NpT ensemble and the Voronoi tesselation, which was previously developed for single-species hard-disk systems, is extended, along with a version of scaled-particle theory, to many-component mixtures. These systems are unusual in the sense...... that their composition is not fixed, but rather determined by a set of internal degeneracies assigned to the differently sized hard disks, where the larger disks have the higher degeneracies. Such systems are models of monolayers of molecules with internal degrees of freedom. The combined set of translational...

  10. Study of the Internal Mechanical response of an asphalt mixture by 3-D Discrete Element Modeling

    DEFF Research Database (Denmark)

    Feng, Huan; Pettinari, Matteo; Hofko, Bernhard

    2015-01-01

    for all the distinct elements. The dynamic modulus and phase angle from uniaxial complex modulus tests of the asphalt mixtures in the laboratory have been collected. A macro-scale Burger’s model was first established and the input parameters of Burger’s contact model were calibrated by fitting......In this paper the viscoelastic behavior of asphalt mixture was investigated by employing a three-dimensional Discrete Element Method (DEM). The cylinder model was filled with cubic array of spheres with a specified radius, and was considered as a whole mixture with uniform contact properties...... with the lab test data of the complex modulus of the asphalt mixture. The Burger’s contact model parameters are usually calibrated for each frequency. While in this research a constant set of Burger’s parameters has been calibrated and used for all the test frequencies, the calibration procedure...

  11. Transport of heavy metals and chemical compatibility of hydraulic conductivity of a compacted sand-bentonite mixture

    Directory of Open Access Journals (Sweden)

    Nanthanit Charoenthaisong

    2008-03-01

    Full Text Available Clayey soils are usually used as barrier material in landfill liners because of its low hydraulic conductivity and high sorption capacity. Bentonite, which consists mainly of montmorillonite, has a high cation exchange capacity resulting in a high retention capacity of heavy metals. Sand is a permeable material but its hydraulic conductivity decreases significantly when mixed with bentonite. However, using a sand-bentonite mixture as landfill liners is questionable, because the hydraulic conductivity of the sand-bentonite mixture may increase when permeated with heavy metal solutions, which are normally found in landfill leachates. In this paper, transport of heavy metals through a compacted sand-bentonite mixture and its chemical compatibility were studied through the batch adsorption test, the column test, and the hydraulic conductivity test.Experimental results indicate that the sorption capacity of the bentonite, ranked in descending order, was Cr3+, Pb2+, Cd2+, Zn2+, and Ni2+, respectively. The diffusion coefficients of the sand-bentonite mixture were in the order of 10-5 cm2/s and the retardation factors were 130, 115, 111, and 90 for Pb2+, Ni2+, Zn2+, and Cd2+, respectively. The hydraulic conductivity of thesand-bentonite mixture was only compatible with a chromium solution having a concentration not greater than 0.001 M.

  12. Screening Estrogenic Activities of Chemicals or Mixtures In Vivo Using Transgenic (cyp19a1b-GFP) Zebrafish Embryos

    OpenAIRE

    François Brion; Yann Le Page; Benjamin Piccini; Olivier Cardoso; Sok-Keng Tong; Bon-chu Chung; Olivier Kah

    2012-01-01

    International audience; The tg(cyp19a1b-GFP) transgenic zebrafish expresses GFP (green fluorescent protein) under the control of the cyp19a1b gene, encoding brain aromatase. This gene has two major characteristics: (i) it is only expressed in radial glial progenitors in the brain of fish and (ii) it is exquisitely sensitive to estrogens. Based on these properties, we demonstrate that natural or synthetic hormones (alone or in binary mixture), including androgens or progestagens, and industria...

  13. Determinants of Exposure to Fragranced Product Chemical Mixtures in a Sample of Twins

    Directory of Open Access Journals (Sweden)

    Matthew O. Gribble

    2015-01-01

    Full Text Available Fragranced product chemical mixtures may be relevant for environmental health, but little is known about exposure. We analyzed results from an olfactory challenge with the synthetic musk fragrance 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethyl-cyclopento-γ-2-benzopyran (HHCB, and a questionnaire about attitudes toward chemical safety and use of fragranced products, in a sample of 140 white and 17 black twin pairs attending a festival in Ohio. Data for each product were analyzed using robust ordered logistic regressions with random intercepts for “twin pair” and “sharing address with twin”, and fixed effects for sex, age, education, and “ever being bothered by fragrances”. Due to the small number of black participants, models were restricted to white participants except when examining racial differences. Overall patterns of association were summarized across product-types through random-effects meta-analysis. Principal components analysis was used to summarize clustering of product use. The dominant axis of variability in fragranced product use was “more vs. less”, followed by a distinction between household cleaning products and personal care products. Overall, males used fragranced products less frequently than females (adjusted proportionate odds ratio 0.55, 95% confidence interval 0.33, 0.93. This disparity was driven by personal care products (0.42, 95% CI: 0.19, 0.96, rather than household cleaning products (0.79, 95% CI: 0.49, 1.25 and was particularly evident for body lotion (0.12, 95% CI: 0.05, 0.27. Overall usage differed by age (0.64, 95% CI: 0.43, 0.95 but only hand soap and shampoo products differed significantly. “Ever being bothered by fragrance” had no overall association (0.92, 95% CI: 0.65, 1.30 but was associated with laundry detergent use (0.46, 95% CI: 0.23, 0.93. Similarly, black vs. white differences on average were not significant (1.34, 95% CI: 0.55, 3.28 but there were apparent differences in use of

  14. Influence of Wetting and Mass Transfer Properties of Organic Chemical Mixtures in Vadose Zone Materials on Groundwater Contamination by Nonaqueous Phase Liquids

    Energy Technology Data Exchange (ETDEWEB)

    Charles J Werth; Albert J Valocchi, Hongkyu Yoon

    2011-05-21

    Previous studies have found that organic acids, organic bases, and detergent-like chemicals change surface wettability. The wastewater and NAPL mixtures discharged at the Hanford site contain such chemicals, and their proportions likely change over time due to reaction-facilitated aging. The specific objectives of this work were to (1) determine the effect of organic chemical mixtures on surface wettability, (2) determine the effect of organic chemical mixtures on CCl4 volatilization rates from NAPL, and (3) accurately determine the migration, entrapment, and volatilization of organic chemical mixtures. Five tasks were proposed to achieve the project objectives. These are to (1) prepare representative batches of fresh and aged NAPL-wastewater mixtures, (2) to measure interfacial tension, contact angle, and capillary pressure-saturation profiles for the same mixtures, (3) to measure interphase mass transfer rates for the same mixtures using micromodels, (4) to measure multiphase flow and interphase mass transfer in large flow cell experiments, all using the same mixtures, and (5) to modify the multiphase flow simulator STOMP in order to account for updated P-S and interphase mass transfer relationships, and to simulate the impact of CCl4 in the vadose zone on groundwater contamination. Results and findings from these tasks and summarized in the attached final report.

  15. Chemical and thermal stability of refrigerant-lubricant mixtures with metals

    Energy Technology Data Exchange (ETDEWEB)

    Huttenlocher, D.F.

    1992-10-09

    This report presents the results of a sealed tube stability study on twenty-one refrigerant-lubricant mixtures selected from the following groupings: HFCs R-32, R-125, R-134, R-134a, R-143a, and R-152a with one or more lubricants selected from among three pentaerythritol esters and three polyalkylene glycols. All lubricants were carefully predried to 25 ppm or less moisture content. HCFCs R-22, R-123, R-124, and R-142b, as well as CFC R-11, with one or more lubricants selected from among two mineral oils and one alkylbenzene fluid. Bach test mixture was aged at three temperature levels.

  16. Chemical and thermal stability of refrigerant-lubricant mixtures with metals. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Huttenlocher, D.F.

    1992-10-09

    This report presents the results of a sealed tube stability study on twenty-one refrigerant-lubricant mixtures selected from the following groupings: HFCs R-32, R-125, R-134, R-134a, R-143a, and R-152a with one or more lubricants selected from among three pentaerythritol esters and three polyalkylene glycols. All lubricants were carefully predried to 25 ppm or less moisture content. HCFCs R-22, R-123, R-124, and R-142b, as well as CFC R-11, with one or more lubricants selected from among two mineral oils and one alkylbenzene fluid. Bach test mixture was aged at three temperature levels.

  17. Richard Rufus's theory of mixture: a medieval explanation of chemical combination.

    Science.gov (United States)

    Weisberg, Michael; Wood, Rega

    2003-05-01

    Richard Rufus of Cornwall offered a novel solution to the problem of mixture raised by Aristotle. The puzzle is that mixts or mixed bodies (blood, flesh, wood, etc.) seem to be unexplainable through logic, even though the world is full of them. Rufus's contribution to this long-standing theoretical debate is the development of a modal interpretation of certain Averroistic doctrines. Rufus's account, which posits that the elemental forms in a mixt are in accidental potential, avoids many of the problems that plagued non-atomistic medieval theories of mixture. This paper is an initial examination of Rufus' account.

  18. Demonstration of a rapidly-swept external cavity quantum cascade laser for rapid and sensitive quantification of chemical mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Brumfield, Brian E.; Taubman, Matthew S.; Phillips, Mark C.

    2016-02-13

    A rapidly-swept external cavity quantum cascade laser (ECQCL) system for fast open-path quantification of multiple chemicals and mixtures is presented. The ECQCL system is swept over its entire tuning range (>100 cm-1) at frequencies up to 200 Hz. At 200 Hz the wavelength tuning rate and spectral resolution are 2x104 cm-1/sec and < 0.2 cm-1, respectively. The capability of the current system to quantify changes in chemical concentrations on millesecond timescales is demonstrated at atmospheric pressure using an open-path multi-pass cell. The detection limits for chemicals ranged from ppb to ppm levels depending on the absorption cross-section.

  19. Passive dosing of polycyclic aromatic hydrocarbon (PAH) mixtures to terrestrial springtails: Linking mixture toxicity to chemical activities, equilibrium lipid concentrations, and toxic units

    DEFF Research Database (Denmark)

    Schmidt, Stine Nørgaard; Holmstrup, Martin; Smith, Kilian E. C.

    2013-01-01

    In the present study, a 7-day mixture toxicity experiment with the terrestrial springtail Folsomia candida was conducted, and the effects linked to three different mixture exposure parameters. Passive dosing from silicone was applied to tightly control exposure levels and compositions of 12 mixture...... exposure in terms of both level and composition, while ∑a, ∑Clipid eq., and ∑TU allowed baseline toxicity to be linked to mixture exposure....

  20. SOLUBILITY, SORPTION AND TRANSPORT OF HYDROPHOBIC ORGANIC CHEMICALS IN COMPLEX MIXTURES

    Science.gov (United States)

    The research summarized in this report focuses on the effects which organic cosolvents have on the sorption and mobility of organic contaminants. This work was initiated In an effort to improve our understanding of the environmental consequences associated with complex mixtur...

  1. Identifying changes in chemical, interfacial and foam properties of ß-lactoglobulin–sodium dodecyl sulphate mixtures

    NARCIS (Netherlands)

    Lech, F.J.; Steltenpool, P.; Meinders, M.B.J.; Sforza, S.; Gruppen, H.; Wierenga, P.A.

    2014-01-01

    Techno-functional properties of proteins, such as foam stability, can be affected by the presence of low-molecular-weight surfactants. In order to understand and control the foam properties of such protein–surfactant mixtures, a thorough characterization of foam and interfacial properties needs to b

  2. Conversion of the chemical concentration of odorous mixtures into odour concentration and odour intensity: a comparison of methods

    CERN Document Server

    Wu, C; Zhao, P; Piringer, M; Schauberger, G

    2015-01-01

    Continuous odour measurements both of emissions as well as ambient concentrations are seldom realised, mainly because of their high costs. They are therefore often substituted by concentration measurements of odorous substances. Then a conversion of the chemical concentrations C (mg m-3) into odour concentrations COD (ouE m-3) and odour intensities OI is necessary. Four methods to convert the concentrations of single substances to the odour concentrations and odour intensities of an odorous mixture are investigated: (1) direct use of measured concentrations, (2) the sum of the odour activity value SOAV, (3) the sum of the odour intensities SOI, and (4) the equivalent odour concentration EOC, as a new method. The methods are evaluated with olfactometric measurements of seven substances as well as their mixtures. The results indicate that the SOI and EOC conversion methods deliver reliable values. These methods use not only the odour threshold concentration but also the slope of the Weber-Fechner law to include...

  3. An Assessment of the Model of Concentration Addition for Predicting the Estrogenic Activity of Chemical Mixtures in Wastewater Treatment Works Effluents

    OpenAIRE

    Thorpe, Karen L.; Gross-Sorokin, Melanie; Johnson, Ian; Brighty, Geoff; Tyler, Charles R.

    2005-01-01

    The effects of simple mixtures of chemicals, with similar mechanisms of action, can be predicted using the concentration addition model (CA). The ability of this model to predict the estrogenic effects of more complex mixtures such as effluent discharges, however, has yet to be established. Effluents from 43 U.K. wastewater treatment works were analyzed for the presence of the principal estrogenic chemical contaminants, estradiol, estrone, ethinylestradiol, and nonylphenol. The measured conce...

  4. Chemical Equilibrium Mixture Computations for Energetic Material Combustion in Closed Vessels

    Science.gov (United States)

    2004-12-01

    are used with well-known equations of state stemming from Redlich , Kwong and Soave (RKS); Benedict, Webb, Rubin, Starling and Han (BWRSH); Becker...mixture of numerous imperfect gases and compressible liquid and solid species with phase transitions for closed-vessel applications . This code minimizes...solid species. The benefits of the computational methods in providing accurate pre- dictions for the applications mentioned previously de- pend

  5. Finding a needle in a chemical haystack: tip-enhanced Raman scattering for studying carbon nanotubes mixtures

    Science.gov (United States)

    Chan, K. L. Andrew; Kazarian, Sergei G.

    2010-11-01

    Tip-enhanced Raman scattering (TERS) has emerged as a powerful analytical tool for measuring chemical images with nanometre spatial resolution. In this paper, the application of TERS to study differentiation of single-walled carbon nanotubes (SWCNTs) with 14 nm spatial resolution is demonstrated by the measurement of a mixture of two different types of SWCNTs as the model sample. The results demonstrate that TERS is a viable tool for the detection and localization of different SWCNTs and amorphous carbon in mixed SWCNTs based on the spectral differences in the radial breathing mode and the D bands.

  6. Finding a needle in a chemical haystack: tip-enhanced Raman scattering for studying carbon nanotubes mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Chan, K L Andrew; Kazarian, Sergei G, E-mail: s.kazarian@imperial.ac.uk [Department of Chemical Engineering, Imperial College London, SW7 2AZ (United Kingdom)

    2010-11-05

    Tip-enhanced Raman scattering (TERS) has emerged as a powerful analytical tool for measuring chemical images with nanometre spatial resolution. In this paper, the application of TERS to study differentiation of single-walled carbon nanotubes (SWCNTs) with 14 nm spatial resolution is demonstrated by the measurement of a mixture of two different types of SWCNTs as the model sample. The results demonstrate that TERS is a viable tool for the detection and localization of different SWCNTs and amorphous carbon in mixed SWCNTs based on the spectral differences in the radial breathing mode and the D bands.

  7. Quantitative NMR spectroscopy of complex technical mixtures using a virtual reference: chemical equilibria and reaction kinetics of formaldehyde-water-1,3,5-trioxane.

    Science.gov (United States)

    Maiwald, Michael; Grützner, Thomas; Ströfer, Eckhard; Hasse, Hans

    2006-07-01

    Quantitative 1H NMR spectroscopy was used to study chemical equilibria and reaction kinetics of both the formation and decomposition of 1,3,5-trioxane in aqueous formaldehyde solutions. The reaction was homogeneously catalyzed with up to 0.10 g g(-1) sulfuric acid at temperatures between 360 and 383 K so that most of the experiments had to be carried out pressurized. The studied mixtures were complex due to the formation of methylene glycol and poly(oxymethylene) glycols in aqueous formaldehyde and the presence of considerable amounts of ionized species. Most common internal standards are decomposed by the hot sulfuric acid and external standards were not applicable using the flow NMR probe or pressurizable NMR sample tubes. Therefore, for the quantification of the small trioxane signals, a novel procedure was applied, in which electronically generated NMR signals were used as highly stable Virtual References (VR). The NMR decoupler channel with wave-form generator was used as the source of the reference signal, which was irradiated into the probe using the lock coil. Details on the experimental procedure are presented. It is shown that the presented method yields reliable quantitative reaction data for the complex studied mixtures.

  8. Immunomodulation of Mytilus hemocytes by individual estrogenic chemicals and environmentally relevant mixtures of estrogens: in vitro and in vivo studies.

    Science.gov (United States)

    Canesi, Laura; Lorusso, Lucia Cecilia; Ciacci, Caterina; Betti, Michele; Rocchi, Marco; Pojana, Giulio; Marcomini, Antonio

    2007-02-15

    Endocrine disrupting compounds (EDCs) are almost ubiquitous in the aquatic environment. In the marine bivalve Mytilus the natural estrogen 17beta-estradiol (E2) and different EDCs have been recently demonstrated to affect the function of the immune cells, the hemocytes. The effects were Tamoxifen-sensitive and were mediated by rapid modulation of kinase-mediated transduction pathways. In this work we compared the in vitro effects of individual estrogenic chemicals (E2, EE: 17alpha-ethynyl estradiol; MES: mestranol; NP: nonylphenol; NP1EC: nonylphenol monoethoxylate carboxylate; BPA: bisphenol A; BP: benzophenone) on hemocyte parameters: lysosomal membrane stability (LMS), phagocytosis, lysozyme release. LMS was the most sensitive effect parameter, showing a decreasing trend at increasing concentrations of estrogens. EC50 values obtained from LMS data were utilized to calculate the estradiol equivalency factor (EEF) for each compound; these EEFs allowed for an estimation of the estrogenic potential of a synthetic mixture with a composition very similar to that previously found in waters of the Venice lagoon. Concentrated mixtures significantly affected hemocyte parameters in vitro and the effects were prevented by Tamoxifen. Significant effects of the mixture were also observed in vivo, at longer exposure times and at concentrations comparable with environmental exposure levels. The results indicate that Mytilus immune parameters can be suitably utilized to evaluate the estrogenic potential of environmental samples.

  9. THYROID DISRUPTING CHEMICALS: CHALLENGES IN ASSESSING NEUROTOXIC RISK FROM ENVIRONMENTAL MIXTURES.

    Science.gov (United States)

    Environmental contaminants are known to act as thyroid disrupting chemicals (TDCs). Broadly defined, TDCs are xenobiotics that alter the structure or function of the thyroid gland, alter regulatory enzymes associated with thyroid hormone (TH) homeostasis, or change circulating o...

  10. Chemical and physical effects induced by heavy cosmic ray analogues on frozen methanol and water ice mixtures

    Science.gov (United States)

    de Barros, A. L. F.; da Silveira, E. F.; Rothard, H.; Langlinay, T.; Boduch, P.

    2014-09-01

    The chemical and physical effects induced by fast heavy-ion irradiation on a frozen mixture of methanol (CH3OH) and water (H2O) at 15 K are analysed. The laboratory experiment described here simulates the energy transfer processes that occur when cosmic rays bombard this particular ice mixture and helps to elucidate the understanding of the radiolysis of ices occurring in interstellar medium grains, at the surfaces of comets, and on icy Solar system bodies. Infrared spectroscopy (FTIR) was used before and during irradiation with a 40 MeV 58Ni11+ ion beam to determine the variation of the main absorption bands of methanol, water and products. In particular, the radiolysis of CH3OH:H2O (1:1) mixture leads to the formation of H2CO, CH4, CO, CO2, HCO and HCOOCH3. Their formation and dissociation cross-sections are determined. H2CO, CH4 and HCOOCH3 molecules have relatively high destruction cross-sections of around 9 × 10-13 cm2. Furthermore, atomic carbon, oxygen and hydrogen budgets are determined and used to verify the stoichiometry of the most abundant molecular species formed. Temperature effects are compared with irradiation effects, and the spectra of samples warmed-up to different temperatures are compared with those of the irradiated CH3OH:H2O mixtures. As an astrophysical application, the CH3OH:H2O dissociation cross-sections due to other ion beam projectiles and energies are predicted assuming validity of the Se3/2 power law; calculation of the integrated dissociation rates confirms the importance of nickel and some other heavy-ion constituents of cosmic rays in astrochemistry.

  11. Comparison of diamond growth with different gas mixtures in microwave plasma asssited chemical vapor deposition (MWCVD

    Directory of Open Access Journals (Sweden)

    Corat Evaldo J.

    2003-01-01

    Full Text Available In this work we study the influence of oxygen addition to several halocarbon-hydrogen gas systems. Diamond growth have been performed in a high power density MWCVD reactor built in our laboratory. The growth experiments are monitored by argon actinometry as a reference to plasma temperature and atomic hydrogen production, and by mass spectrometry to compare the exhaust gas composition. Atomic hydrogen actinometry revealed that the halogen presence in the gas phase is responsible for a considerable increase of atomic hydrogen concentration in the gas phase. Mass spectrometry shows similar results for all gas mixtures tested. Growth studies with oxygen addition to CF4/H2, CCl4/H2, CCl2F2/H2 and CH3Cl/H2 reveals that oxygen increases the carbon solubility in the gas phase but no better diamond growth conditions were found. Halogens are not, per se, eligible for diamond growth. All the possible advantages, as the higher production of atomic hydrogen, have been suppressed by the low carbon solubility in the gas phase, even when oxygen is added. The diamond growth with small amount of CF4 added to CH4/H2 mixture is not aggressive to the apparatus but brings several advantages to the process.

  12. Endocrine-disrupting chemicals and oil and natural gas operations: Potential environmental contamination and recommendations to assess complex environmental mixtures

    Science.gov (United States)

    Kassotis, Christopher D.; Tillitt, Donald E.; Lin, Chung-Ho; McElroy, Jane A.; Nagel, Susan C.

    2015-01-01

    Background: Hydraulic fracturing technologies, developed over the last 65 years, have only recently been combined with horizontal drilling to unlock oil and gas reserves previously deemed inaccessible. While these technologies have dramatically increased domestic oil and natural gas production, they have also raised concerns for the potential contamination of local water supplies with the approximately 1,000 chemicals used throughout the process, including many known or suspected endocrine-disrupting chemicals.Objectives: We discuss the need for an endocrine component to health assessments for drilling-dense regions in the context of hormonal and anti-hormonal activities for chemicals used.Methods: We discuss the literature on 1) surface and ground water contamination by oil and gas extraction operations, and 2) potential human exposure, particularly in context of the total hormonal and anti-hormonal activities present in surface and ground water from natural and anthropogenic sources, with initial analytical results and critical knowledge gaps discussed.Discussion: In light of the potential for environmental release of oil and gas chemicals that can disrupt hormone receptor systems, we recommend methods for assessing complex hormonally active environmental mixtures.Conclusions: We describe a need for an endocrine-centric component for overall health assessments and provide supporting information that using this may help explain reported adverse health trends as well as help develop recommendations for environmental impact assessments and monitoring programs.

  13. Investigation of shock-induced and shock-assisted chemical reactions in molybdenum-silicon powder mixtures

    Science.gov (United States)

    Vandersall, Kevin Stewart

    1999-10-01

    In this research, chemical reactions occurring in molybdenum and silicon powder mixtures under "shock-induced" (those occurring during the high-pressure shock state) and "shock-assisted" (those occurring subsequent to the shock event, but due to bulk temperature increases) conditions were investigated. Differences in the densities and yield strengths of the two constituents, in addition to the large heat of reaction associated with molybdenum disilicide (MoSi2) formation can lead to shock-induced as well as shock-assisted reactions, which make this an ideal system to delineate the kinetics and mechanisms of reactions occurring in shock-compressed powder mixtures. Shock recovery experiments performed on Mo + 2 Si powder mixtures employing cylindrical implosion geometry showed thermally initiated reactions. A mixed phase eutectic type microstructure of MoSi2 and Mo 5Si3, resulting from reaction occurring due to melting of both reactants, was observed in axial regions of the cylindrical compacts. In regions surrounding the mach stem, melting of only silicon and reaction occurring via dissolution and re-precipitation forming MoSi2 spherules surrounding molybdenum particles in a melted and solidified silicon matrix was observed. The planar pressure shock recovery geometry showed a single phase MoSi2, microstructure formed due to a solid-state pressure-induced reaction process. The time-resolved instrumented experiments were performed using a single stage gas gun in the velocity range of 500 m/s to 1 km/s, and employed poly-vinyl di-flouride (PVDF) stress gauges placed at the front and rear surfaces of the powder to determine the crush strength, densification history, and reaction initiation threshold conditions. Time-resolved experiments performed on ˜58% dense Mo + 2 Si powder mixtures at input stresses less than 4 GPa, showed characteristics of powder densification and dispersed propagated wave stress profiles with rise time >˜40 nanoseconds. At input stress between

  14. Hygroscopic properties of potassium chloride and its internal mixtures with organic compounds relevant to biomass burning aerosol particles

    Science.gov (United States)

    Jing, Bo; Peng, Chao; Wang, Yidan; Liu, Qifan; Tong, Shengrui; Zhang, Yunhong; Ge, Maofa

    2017-01-01

    While water uptake of aerosols exerts considerable impacts on climate, the effects of aerosol composition and potential interactions between species on hygroscopicity of atmospheric particles have not been fully characterized. The water uptake behaviors of potassium chloride and its internal mixtures with water soluble organic compounds (WSOCs) related to biomass burning aerosols including oxalic acid, levoglucosan and humic acid at different mass ratios were investigated using a hygroscopicity tandem differential mobility analyzer (HTDMA). Deliquescence points of KCl/organic mixtures were observed to occur at lower RH values and over a broader RH range eventually disappearing at high organic mass fractions. This leads to substantial under-prediction of water uptake at intermediate RH. Large discrepancies for water content between model predictions and measurements were observed for KCl aerosols with 75 wt% oxalic acid content, which is likely due to the formation of less hygroscopic potassium oxalate from interactions between KCl and oxalic acid without taken into account in the model methods. Our results also indicate strong influence of levoglucosan on hygroscopic behaviors of multicomponent mixed particles. These findings are important in further understanding the role of interactions between WSOCs and inorganic salt on hygroscopic behaviors and environmental effects of atmospheric particles. PMID:28240258

  15. Numerical simulation of nanosecond pulsed DBD in lean methane-air mixture for typical conditions in internal engines

    Science.gov (United States)

    Takana, Hidemasa; Nishiyama, Hideya

    2014-06-01

    Detailed two-dimensional numerical simulations of a high energy loading nanosecond dc pulse DBD in a lean methane-air mixture were conducted for plasma-assisted combustion by integrating individual models of plasma chemistry, photoionization and energy loading. The DBD streamer propagation process with radical productions was clarified at 10 atm and 600 K as under the condition of actual internal engines at ignition. Energy is loaded to the streamer first by the formation of plasma channel and then ceased due to the self-shielding effect. Because of the inversed electric field in a discharge space during decrease in applied voltage, energy is loaded to the discharge again. It was found that higher energy is loaded to the DBD streamer for larger dielectric constant even at lower applied voltage, and higher number density of oxygen radical is produced at almost the same radical production efficiency.

  16. Symposium introduction: the first joint American Chemical Society Agricultural and Food Chemistry Division and the American Chemical Society International Chemical Sciences Chapter in Thailand

    Science.gov (United States)

    The American Chemical Society (ACS) Agricultural and Food Chemistry Division (AGFD) and the ACS International Chemical Sciences Chapter in Thailand (ICSCT) worked together to stage the “1st Joint ACS AGFD - ACS ICSCT Symposium on Agricultural and Food Chemistry,” which was held in Bangkok, Thailand ...

  17. Risk managment of complex aquifers contaminated by chemical mixtures : numerical tools and human health risk assessment

    OpenAIRE

    Henri, Christopher

    2015-01-01

    Human impact on groundwater resources has led to a rapid growth of social concerns worldwide owing to an increasing presence of toxic chemicals released in the subsurface. Risk assessment provides the scientific tool needed to quantify the actual thread that these potential hazards pose to human health. Specifically, risk analysis enables decision makers to answer: What can happen? How likely is it to happen? What can be the consequences? Risk assessment is in this context essential. However,...

  18. The Toxicology of Chemical Mixtures Risk Assessment for Human and Ecological Receptors

    Science.gov (United States)

    2005-10-01

    AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR’S ACRONYM(S) kir Force Materiel Command*** HEPB kir Force Research Laboratory iuman Effectiveness... cancer slope factor) as are used for individual chemicals, so the calculations are relatively simple and familiar (U.S. EPA, 2000). Of course, the same...skin painting assays served as the short term assay; human lung cancer epidemiological data were available for roofing tar and coke oven emissions

  19. Long-term presence of tree species but not chemical diversity affect litter mixture effects on decomposition in a neotropical rainforest.

    Science.gov (United States)

    Barantal, Sandra; Roy, Jacques; Fromin, Nathalie; Schimann, Heidy; Hättenschwiler, Stephan

    2011-09-01

    Plant litter diversity effects on decomposition rates are frequently reported, but with a strong bias towards temperate ecosystems. Altered decomposition and nutrient recycling with changing litter diversity may be particularly important in tree species-rich tropical rainforests on nutrient-poor soils. Using 28 different mixtures of leaf litter from 16 Amazonian rainforest tree species, we tested the hypothesis that litter mixture effects on decomposition increase with increasing functional litter diversity. Litter mixtures and all single litter species were exposed in the field for 9 months using custom-made microcosms with soil fauna access. In order to test the hypothesis that the long-term presence of tree species contributing to the litter mixtures increases mixture effects on decomposition, microcosms were installed in a plantation at sites including the respective tree species composition and in a nearby natural forest where these tree species are absent. We found that mixture decomposition deviated from predictions based on single species, with predominantly synergistic effects. Functional litter diversity, defined as either richness, evenness, or divergence based on a wide range of chemical traits, did not explain the observed litter mixture effects. However, synergistic effects in litter mixtures increased with the long-term presence of tree species contributing to these mixtures as the home field advantage hypothesis assumes. Our data suggest that complementarity effects on mixed litter decomposition may emerge through long-term interactions between aboveground and belowground biota.

  20. BEHAVIOR OF SURFACTANT MIXTURES AT SOLID/LIQUID AND OIL/LIQUID INTERFACES IN CHEMICAL FLOODING SYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    Prof. P. Somasundaran

    2003-03-31

    The aim of the project is to develop a knowledge base to help with the design of enhanced process for mobilizing and extracting untrapped oil. We emphasize on evaluating novel surfactant mixtures and on obtaining optimum combinations of the surfactants in chemical flooding EOR process. An understanding of the micellar shape and size is crucial since these physical properties directly determine the crude oil removal efficiency. Analytical ultracentrifugation experiments were used to test the multi-micelle model proposed earlier and formulate the relationships between mixed micelle formation and the surfactant structure. Information on partial specific volume of surfactants and their mixtures is required to treat analytical ultracentrifuge data. In the last report, it was noted that the partial specific volumes of the sugar-based surfactants obtained experimentally did not agree with those from theoretical calculations. A scrutiny of partial specific volumes of the four sugar-based surfactants revealed that conformational changes upon micelle formation are responsible for the large deviation. From sedimentation equilibrium experiments, two types of micelles were identified for the nonionic polyethylene surfactant and its mixtures with the sugar-based surfactant, dodecyl maltoside. The average aggregation numbers of n-dodecyl-{beta}-D-maltoside and nonyl phenol ethoxylated decyl ether agreed with those reported in literature using other techniques. Our study displayed, for the first time, that small micelles might coexist with large micelles at high concentrations due to unique structures of the surfactant although classical thermodynamic theory supports only one type of micelle. Initial dynamic light scattering results support the results for the same mixed surfactant system from analytical ultracentrifuge equilibrium technique. The implication of this finding lies in the fact that efficiency of oil recovery will be improved due to the large micellar size, its

  1. Numerical simulation of CO2 separation from gas mixtures in membrane modules: Effect of chemical absorbent

    Directory of Open Access Journals (Sweden)

    Seyed Mohammad Reza Razavi

    2016-01-01

    Full Text Available In this study, a mathematical model is proposed for prediction of CO2 absorption from N2/CO2 mixture by potassium threonate in a hollow-fiber membrane contactor (HFMC. CFD technique using numerical method of finite element was applied to solve the governing equations of model. Effect of different factors on CO2 absorption was analyzed and for investigation of absorbent type effect, functioning of potassium threonate was compared with diethanolamine (DEA. Axial and radial diffusion can be described with the two dimensional model established in this work. The obtained simulation results were compared with the reported experimental data to ensure accuracy of the model predictions. Comparison of model results with experimental data revealed that the developed model can well predict CO2 capture by potassium threonate in HFMCs. Increment of absorbent flow rate and concentration eventuate in enhancement of CO2 absorption. On the other hand, capture of CO2 will be reduced with increment of gas flow rate. According to the model results, potassium threonate can be considered as a more efficient absorbent as compared with DEA.

  2. Adsorption of polyelectrolytes and polyelectrolytes-surfactant mixtures at surfaces: a physico-chemical approach to a cosmetic challenge.

    Science.gov (United States)

    Llamas, Sara; Guzmán, Eduardo; Ortega, Francisco; Baghdadli, Nawel; Cazeneuve, Colette; Rubio, Ramón G; Luengo, Gustavo S

    2015-08-01

    The use of polymer and polymer - surfactant mixtures for designing and developing textile and personal care cosmetic formulations is associated with various physico-chemical aspects, e.g. detergency and conditioning in the case of hair or wool, that determine their correct performances in preserving and improving the appearance and properties of the surface where they are applied. In this work, special attention is paid to the systems combining polycations and negatively charged surfactants. The paper introduces the hair surface and presents a comprehensive review of the adsorption properties of these systems at solid-water interfaces mimicking the negative charge and surface energy of hair. These model surfaces include mixtures of thiols that confer various charge densities to the surface. The kinetics and factors that govern the adsorption are discussed from the angle of those used in shampoos and conditioners developed by the cosmetic industry. Finally, systems able to adsorb onto negatively charged surfaces regardless of the anionic character are presented, opening new ways of depositing conditioning polymers onto keratin substrates such as hair.

  3. The capric and lauric acid mixture with chemical additives as latent heat storage materials for cooling application

    Energy Technology Data Exchange (ETDEWEB)

    Roxas-Dimaano, M.N. [University of Santo Tomas, Manila (Philippines). Research Center for the Natural Sciences; Watanabe, T. [Tokyo Institute of Technology (Japan). Research Laboratory for Nuclear Reactors

    2002-09-01

    The mixture of capric acid and lauric acid (C-L acid), with the respective mole composition of 65% and 35%, is a potential phase change material (PCM). Its melting point of 18.0{sup o}C, however, is considered high for cooling application of thermal energy storage. The thermophysical and heat transfer characteristics of the C-L acid with some organic additives are investigated. Compatibility of C-L acid combinations with additives in different proportions and their melting characteristics are analyzed using the differential scanning calorimeter (DSC). Among the chemical additives, methyl salicylate, eugenol, and cineole presented the relevant melting characteristics. The individual heat transfer behavior and thermal storage performance of 0.1 mole fraction of these additives in the C-L acid mixture are evaluated. The radial and axial temperature distribution during charging and discharging at different concentrations of selected PCM combinations are experimentally determined employing a vertical cylindrical shell and tube heat exchanger. The methyl salicylate in the C-L acid provided the most effective additive in the C-L acid. It demonstrated the least melting band width aimed at lowering the melting point of the C-L acid with the highest heat of fusion value with relatively comparable rate of heat transfer. Furthermore, the thermal performance based on the total amount of transferred energy and their rates, established the PCM's latent heat storage capability. (author)

  4. A DFT based equilibrium study of a chemical mixture Tachyhydrite and their lower hydrates for long term heat storage

    Science.gov (United States)

    Pathak, A. D.; Nedea, S. V.; Zondag, H. A.; Rindt, C. C. M.; Smeulders, D. M. J.

    2016-09-01

    Chloride based salt hydrates are promising materials for seasonal heat storage. However, hydrolysis, a side reaction, deteriorates, their cycle stability. To improve the kinetics and durability, we have investigated the optimum operating conditions of a chemical mixture of CaCl2 and MgCl2 hydrates. In this study, we apply a GGA-DFT to gain insight into the various hydrates of CaMg2Cl6. We have obtained the structural properties, atomic charges and vibrational frequencies of CaMg2Cl6 hydrates. The entropic contribution and the enthalpy change are quantified from ground state energy and harmonic frequencies. Subsequently, the change in the Gibbs free energy of thermolysis was obtained under a wide range of temperature and pressure. The equilibrium product concentration of thermolysis can be used to design the seasonal heat storage system under different operating conditions.

  5. The response of the polarized Fermi mixture to an artificial vector potential: The interaction strength and imbalance chemical potential effects

    Science.gov (United States)

    Ebrahimian, N.; Safiee, Z.

    2017-03-01

    We consider a polarized Fermi mixture (with normal-superfluid phase separation), subjected to artificial vector potential. We concentrate on the BCS regime with various interaction strengths and numerically obtain the polarisability of the system. We obtain the functional dependence of the polarisability of the system on frequency and the relevant physical parameters, namely the interaction strength, the mass ratio, the average and imbalance chemical potentials. Also, we find the special frequency (ωs), for which the rate of the response of system to the potential is changed and the cut-off frequency (ωcutoff), for which the response starts to become infinity. We investigate the behavior of the curves of polarisability versus proper physical parameters for ω physical parameters. Finally, the system's response can be controlled by relevant physical parameters, such as interaction strength.

  6. A probe on the intermolecular forces in diisopropyl ether-n-butyric acid mixture by dielectric, FTIR studies and quantum chemical calculations.

    Science.gov (United States)

    Arivazhagan, G; Shanmugam, R; Elangovan, A

    2013-03-15

    The results of FTIR spectral measurement on equimolar diisopropyl ether-butyric acid binary mixture and quantum chemical calculations on the complex molecule have been presented. Dielectric studies have been carried out on the binary mixture over the entire composition range and at four different temperatures 303 K, 308 K, 313 K and 318 K. n-Butyric acid seems to prefer less polar ether to interact with it. It appears that the usual interpretation of variation of static dielectric constant and positive deviation of excess permittivity from ideal mixture behavior needs to be relooked.

  7. General baseline toxicity QSAR for nonpolar, polar and ionisable chemicals and their mixtures in the bioluminescence inhibition assay with Aliivibrio fischeri.

    Science.gov (United States)

    Escher, Beate I; Baumer, Andreas; Bittermann, Kai; Henneberger, Luise; König, Maria; Kühnert, Christin; Klüver, Nils

    2017-02-15

    The Microtox assay, a bioluminescence inhibition assay with the marine bacterium Aliivibrio fischeri, is one of the most popular bioassays for assessing the cytotoxicity of organic chemicals, mixtures and environmental samples. Most environmental chemicals act as baseline toxicants in this short-term screening assay, which is typically run with only 30 min of exposure duration. Numerous Quantitative Structure-Activity Relationships (QSARs) exist for the Microtox assay for nonpolar and polar narcosis. However, typical water pollutants, which have highly diverse structures covering a wide range of hydrophobicity and speciation from neutral to anionic and cationic, are often outside the applicability domain of these QSARs. To include all types of environmentally relevant organic pollutants we developed a general baseline toxicity QSAR using liposome-water distribution ratios as descriptors. Previous limitations in availability of experimental liposome-water partition constants were overcome by reliable prediction models based on polyparameter linear free energy relationships for neutral chemicals and the COSMOmic model for charged chemicals. With this QSAR and targeted mixture experiments we could demonstrate that ionisable chemicals fall in the applicability domain. Most investigated water pollutants acted as baseline toxicants in this bioassay, with the few outliers identified as uncouplers or reactive toxicants. The main limitation of the Microtox assay is that chemicals with a high melting point and/or high hydrophobicity were outside of the applicability domain because of their low water solubility. We quantitatively derived a solubility cut-off but also demonstrated with mixture experiments that chemicals inactive on their own can contribute to mixture toxicity, which is highly relevant for complex environmental mixtures, where these chemicals may be present at concentrations below the solubility cut-off.

  8. World War I, international participation and reorganisation of the Japanese chemical community.

    Science.gov (United States)

    Kikuchi, Yoshiyuki

    2011-07-01

    What kind of "war" did Japanese chemists fight during World War I, and what impact did their experiences have on Japanese chemistry in its aftermath? By focusing on the role of Jōji Sakurai (1858-1939), this paper attempts to answer these questions by looking at the drastic changes in the international relationships of the Japanese chemical community caused by the war. It examines how the Japanese National Research Council was established in 1920 as part of the International Research Council, a product of the reconfiguration of international scientific powers triggered by World War I. This paper argues that Sakurai advocated the establishment of the National Research Council after the American model of wartime mobilisation of science, coordinated fractured Japanese chemical communities for international functions, and facilitated Japan's participation and increased influence in international scientific associations such as the International Union of Pure and Applied Chemistry, established in 1919.

  9. Kinetics of physico-chemical processes during intensive mechanical processing of ZnO-MnO{sub 2} powder mixture

    Energy Technology Data Exchange (ETDEWEB)

    Kakazey, M.; Vlasova, M.; Dominguez-Patino, M. [CIICAp-Universidad Autonoma del Estado de Morelos, Cuernavaca (Mexico); Juarez-Arellano, E.A., E-mail: eajuarez@unpa.edu.mx [Universidad del Papaloapan, Tuxtepec, Oaxaca (Mexico); Bykov, A. [Institute for Problems of Materials Science of NASU, Kyiv (Ukraine); Leon, I. [CIQ-Universidad Autonoma del Estado de Morelos, Cuernavaca (Mexico); Siqueiros-Diaz, A. [FCQI-Universidad Autonoma del Estado de Morelos, Cuernavaca (Mexico)

    2011-10-15

    Experimental results of electron paramagnetic resonance spectra, X-ray diffraction, scanning electron microscopy and infrared spectroscopy demonstrate that the kinetic of the physical and chemical processes that takes place during prolonged intensive mechanical processing (MP, 03120min) of powder mixtures of 50%wt ZnO+50%wt MnO{sub 2} can be described as a three stage process. (1) 030min, particles destruction, formation of superficial defects, fast increment of sample average temperature (from 290 to {approx}600K) and annealing of defects with the lowest energy of activation E{sub ac}. (2) 30390min, further particle destruction, slow increment of sample average temperature (from {approx}600 to {approx}700K), formation and growth of a very disordered layer of {beta}-MnO{sub 2} around ZnO particles, dehydration of MnO{sub 2}, formation of solid solution of Mn{sup 2+} ions in ZnO, formation of nano-quasiamorphous states in the ZnO-MnO{sub 2} mixture and onset of the formation of the ZnMnO{sub 3} phase. (3) 3903120min, the sample average temperature remains constant ({approx}700K), the reaction is completed and the spinel ZnMnO{sub 3} phase with a unit cell a=8.431(1) A and space group Fd3-barm is the only phase present in the sample. No ferromagnetism at room temperature was detected in this study. - Highlights: > The kinetics during mechanical processing of ZnO-MnO{sub 2} samples is a three stage process. > First stage, reduction of crystallites size and accumulation of defects. > Second stage, nano-quasiamorphous states formation and onset of the ZnMnO{sub 3} phase. > Third stage, complete reaction to the spinel ZnMnO{sub 3} phase.

  10. BEHAVIOR OF SURFACTANT MIXTURES AT SOLID/LIQUID AND OIL/LIQUID INTERFACES IN CHEMICAL FLOODING SYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    P. Somasundaran

    2004-11-20

    The aim of the project is to develop a knowledge base to help the design of enhanced processes for mobilizing and extracting untrapped oil. We emphasize evaluation of novel surfactant mixtures and obtaining optimum combinations of the surfactants for efficient chemical flooding EOR processes. In this regard, an understanding of the aggregate shape, size and structure is crucial since these properties govern the crude oil removal efficiency. During the three-year period, the adsorption and aggregation behavior of sugar-based surfactants and their mixtures with other types of surfactants have been studied. Sugar-based surfactants are made from renewable resources, nontoxic and biodegradable. They are miscible with water and oil. These environmentally benign surfactants feature high surface activity, good salinity, calcium and temperature tolerance, and unique adsorption behavior. They possess the characteristics required for oil flooding surfactants and have the potential for replacing currently used surfactants in oil recovery. A novel analytical ultracentrifugation technique has been successfully employed for the first time, to characterize the aggregate species present in mixed micellar solution due to its powerful ability to separate particles based on their size and shape and monitor them simultaneously. Analytical ultracentrifugation offers an unprecedented opportunity to obtain important information on mixed micelles, structure-performance relationship for different surfactant aggregates in solution and their role in interfacial processes. Initial sedimentation velocity investigations were conducted using nonyl phenol ethoxylated decyl ether (NP-10) to choose the best analytical protocol, calculate the partial specific volume and obtain information on sedimentation coefficient, aggregation mass of micelles. Four softwares: OptimaTM XL-A/XL-I data analysis software, DCDT+, Svedberg and SEDFIT, were compared for the analysis of sedimentation velocity

  11. BEHAVIOR OF SURFACTANT MIXTURE AT SOLID/LIQUID AND OIL/LIQUID INTERFACE IN CHEMICAL FLOODING SYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    Prof. P. Somasundaran

    2002-03-01

    The aim of the project is to develop and evaluate efficient novel surfactant mixtures for enhanced oil recovery. Preliminary ultra-filtration tests suggest that two kinds of micelles may exist in binary surfactant mixtures at different concentrations. Due to the important role played in interfacial processes by micelles as determined by their structures, focus of the current work is on the delineation of the relationship between such aggregate structures and chemical compositions of the surfactants. A novel analytical centrifuge application is explored to generate information on structures of different surfactants aggregates. In this report, optical systems, typical output of the analytical ultracentrifuge results and four basic experiments are discussed. Initial sedimentation velocity investigations were conducted using nonyl phenol ethoxylated decyl ether (NP-10) to choose the best analytical protocol, calculate the partial specific volume and obtain information on sedimentation coefficient, aggregation mass of micelles. The partial specific volume was calculated to be 0.920. Four softwares: Optima{trademark} XL-A/XL-I data analysis software, DCDT+, Svedberg and SEDFIT, were compared for the analysis of sedimentation velocity experimental data. The sedimentation coefficient and aggregation number of NP-10 micelles obtained using the first three softwares at 25 C are 209, 127, and 111, respectively. The last one is closest to the result from Light Scattering. The reason for the differences in numbers obtained using the three softwares is discussed. Based on these tests, Svedberg and SEDFIT analysis are chosen for further studies. This approach using the analytical ultracentrifugation offers an unprecedented opportunity now to obtain important information on mixed micelles and their role in interfacial processes.

  12. Design Concepts for Co-Production of Power, Fuels & Chemicals Via Coal/Biomass Mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Rao, A. D.; Chen, Q.; Samuelsen, G. S.

    2012-09-30

    The overall goal of the program is to develop design concepts, incorporating advanced technologies in areas such as oxygen production, feed systems, gas cleanup, component separations and gas turbines, for integrated and economically viable coal and biomass fed gasification facilities equipped with carbon capture and storage for the following scenarios: (i) coproduction of power along with hydrogen, (ii) coproduction of power along with fuels, (iii) coproduction of power along with petrochemicals, and (iv) coproduction of power along with agricultural chemicals. To achieve this goal, specifically the following objectives are met in this proposed project: (i) identify advanced technology options and innovative preliminary design concepts that synergistically integrate plant subsections, (ii) develop steady state system simulations to predict plant efficiency and environmental signature, (iii) develop plant cost estimates by capacity factoring major subsystems or by major equipment items where required, and then capital, operating and maintenance cost estimates, and (iv) perform techno- economic analyses for the above described coproduction facilities. Thermal efficiencies for the electricity only cases with 90% carbon capture are 38.26% and 36.76% (HHV basis) with the bituminous and the lignite feedstocks respectively. For the coproduction cases (where 50% of the energy exported is in the form of electricity), the electrical efficiency, as expected, is highest for the hydrogen coproduction cases while lowest for the higher alcohols (ethanol) coproduction cases. The electrical efficiencies for Fischer-Tropsch coproduction cases are slightly higher than those for the methanol coproduction cases but it should be noted that the methanol (as well as the higher alcohol) coproduction cases produce the finished coproduct while the Fischer-Tropsch coproduction cases produce a coproduct that requires further processing in a refinery. The cross comparison of the thermal

  13. Methanol Droplet Extinction in Oxygen/Carbon-dioxide/Nitrogen Mixtures in Microgravity: Results from the International Space Station Experiments

    Science.gov (United States)

    Nayagam, Vedha; Dietrich, Daniel L.; Ferkul, Paul V.; Hicks, Michael C.; Williams, Forman A.

    2012-01-01

    Motivated by the need to understand the flammability limits of condensed-phase fuels in microgravity, isolated single droplet combustion experiments were carried out in the Combustion Integrated Rack Facility onboard the International Space Station. Experimental observations of methanol droplet combustion and extinction in oxygen/carbon-dioxide/nitrogen mixtures at 0.7 and 1 atmospheric pressure in quiescent microgravity environment are reported for initial droplet diameters varying between 2 mm to 4 mm in this study.The ambient oxygen concentration was systematically lowered from test to test so as to approach the limiting oxygen index (LOI) at fixed ambient pressure. At one atmosphere pressure, ignition and some burning were observed for an oxygen concentration of 13% with the rest being nitrogen. In addition, measured droplet burning rates, flame stand-off ratios, and extinction diameters are presented for varying concentrations of oxygen and diluents. Simplified theoretical models are presented to explain the observed variations in extinction diameter and flame stand-off ratios.

  14. Mixture effects at very low doses with combinations of anti-androgenic pesticides, antioxidants, industrial pollutant and chemicals used in personal care products

    Energy Technology Data Exchange (ETDEWEB)

    Orton, Frances; Ermler, Sibylle; Kugathas, Subramaniam [Institute for the Environment, Brunel University, Kingston Lane, Uxbridge UB8 3PH (United Kingdom); Rosivatz, Erika [Institute of Chemical Biology, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom); Scholze, Martin [Institute for the Environment, Brunel University, Kingston Lane, Uxbridge UB8 3PH (United Kingdom); Kortenkamp, Andreas, E-mail: andreas.kortenkamp@brunel.ac.uk [Institute for the Environment, Brunel University, Kingston Lane, Uxbridge UB8 3PH (United Kingdom)

    2014-08-01

    Many xenobiotics have been identified as in vitro androgen receptor (AR) antagonists, but information about their ability to produce combined effects at low concentrations is missing. Such data can reveal whether joint effects at the receptor are induced at low levels and may support the prioritisation of in vivo evaluations and provide orientations for the grouping of anti-androgens in cumulative risk assessment. Combinations of 30 AR antagonists from a wide range of sources and exposure routes (pesticides, antioxidants, parabens, UV-filters, synthetic musks, bisphenol-A, benzo(a)pyrene, perfluorooctane sulfonate and pentabromodiphenyl ether) were tested using a reporter gene assay (MDA-kb2). Chemicals were combined at three mixture ratios, equivalent to single components' effect concentrations that inhibit the action of dihydrotesterone by 1%, 10% or 20%. Concentration addition (CA) and independent action were used to calculate additivity expectations. We observed complete suppression of dihydrotestosterone effects when chemicals were combined at individual concentrations eliciting 1%, 10% or 20% AR antagonistic effect. Due to the large number of mixture components, the combined AR antagonistic effects occurred at very low concentrations of individual mixture components. CA slightly underestimated the combined effects at all mixture ratios. In conclusion, large numbers of AR antagonists from a wide variety of sources and exposure routes have the ability of acting together at the receptor to produce joint effects at very low concentrations. Significant mixture effects are observed when chemicals are combined at concentrations that individually do not induce observable AR antagonistic effects. Cumulative risk assessment for AR antagonists should apply grouping criteria based on effects where data are available, rather than on criteria of chemical similarity. - Highlights: • Mixtures of AR antagonists at low individual concentrations cause complete inhibition

  15. Orientation of sustainable management of chemical company with international activity

    Directory of Open Access Journals (Sweden)

    Valéria da Veiga Dias

    2013-04-01

    Full Text Available The search for new business possibilities, either through international activities and capture niche markets appear as a distinct trend among organizations that target growth. For this growing number of organizations intent on investing in new issues related to values such as citizenship, ethics and environmental concerns. There is the adoption of a more responsive to the community or even the acceptance of responsibility for the impacts of their production processes, inserting themselves in what was initially called the Social Responsibility within the business context and developed the concept of Elkington (1998 generated a discussion about a new movement that was called a sustainable paradigm. It was observed generally that sustainable management is still very close to supporting tools and not as part of the construction of corporate strategy although it is possible to realize that they seek a greater involvement in this direction when they start to review their strategies. This question can be perceived at different levels between the companies, but which shows the issue is the lack of direct indicators for investment and sustainable return. Sustainable management proved to be a source of opportunity for overseas business for the companies studied, as preparation for work with environmental legislation, global requirements, raw materials and environmentally friendly processes organizations prepared to market in the global sphere, and Brazil note that the innovative products for their production process and / or alternative raw material still do not get the spotlight. Acting in a sustainable manner enables the development of strategies agreed with conscious posture and changes in cultural terms in general, which can create new opportunities for those who can keep up with the global business scenario.

  16. PACKAGE (Plasma Analysis, Chemical Kinetics and Generator Efficiency): a computer program for the calculation of partial chemical equilibrium/partial chemical rate controlled composition of multiphased mixtures under one dimensional steady flow

    Energy Technology Data Exchange (ETDEWEB)

    Yousefian, V.; Weinberg, M.H.; Haimes, R.

    1980-02-01

    The NASA CEC Code was the starting point for PACKAGE, whose function is to evaluate the composition of a multiphase combustion product mixture under the following chemical conditions: (1) total equilibrium with pure condensed species; (2) total equilibrium with ideal liquid solution; (3) partial equilibrium/partial finite rate chemistry; and (4) fully finite rate chemistry. The last three conditions were developed to treat the evolution of complex mixtures such as coal combustion products. The thermodynamic variable pairs considered are either pressure (P) and enthalpy, P and entropy, at P and temperature. Minimization of Gibbs free energy is used. This report gives detailed discussions of formulation and input/output information used in the code. Sample problems are given. The code development, description, and current programming constraints are discussed. (DLC)

  17. Chemical and structural analysis of enhanced biochars: thermally treated mixtures of biochar, chicken litter, clay and minerals.

    Science.gov (United States)

    Lin, Y; Munroe, P; Joseph, S; Ziolkowski, A; van Zwieten, L; Kimber, S; Rust, J

    2013-03-01

    In this study biochar mixtures comprising a Jarrah-based biochar, chicken litter (CL), clay and other minerals were thermally treated, via torrefaction, at moderate temperatures (180 and 220 °C). The objectives of this treatment were to reduce N losses from CL during processing and to determine the effect of both the type of added clay and the torrefaction temperature on the structural and chemical properties of the final product, termed as an enhanced biochar (EB). Detailed characterisation indicated that the EBs contained high concentrations of plant available nutrients. Both the nutrient content and plant availability were affected by torrefaction temperature. The higher temperature (220 °C) promoted the greater decomposition of organic matter in the CL and dissociated labile carbon from the Jarrah-based biochar, which produced a higher concentration of dissolved organic carbon (DOC). This DOC may assist to solubilise mineral P, and may also react with both clay and minerals to block active sites for P adsorption. This subsequently resulted in higher concentrations of plant available P. Nitrogen loss was minimised, with up to 73% of the initial total N contained in the feedstock remaining in the final EB. However, N availability was affected by both torrefaction temperature and the nature of the clay minerals added.

  18. Screening estrogenic activities of chemicals or mixtures in vivo using transgenic (cyp19a1b-GFP zebrafish embryos.

    Directory of Open Access Journals (Sweden)

    François Brion

    Full Text Available The tg(cyp19a1b-GFP transgenic zebrafish expresses GFP (green fluorescent protein under the control of the cyp19a1b gene, encoding brain aromatase. This gene has two major characteristics: (i it is only expressed in radial glial progenitors in the brain of fish and (ii it is exquisitely sensitive to estrogens. Based on these properties, we demonstrate that natural or synthetic hormones (alone or in binary mixture, including androgens or progestagens, and industrial chemicals induce a concentration-dependent GFP expression in radial glial progenitors. As GFP expression can be quantified by in vivo imaging, this model presents a very powerful tool to screen and characterize compounds potentially acting as estrogen mimics either directly or after metabolization by the zebrafish embryo. This study also shows that radial glial cells that act as stem cells are direct targets for a large panel of endocrine disruptors, calling for more attention regarding the impact of environmental estrogens and/or certain pharmaceuticals on brain development. Altogether these data identify this in vivo bioassay as an interesting alternative to detect estrogen mimics in hazard and risk assessment perspective.

  19. Screening estrogenic activities of chemicals or mixtures in vivo using transgenic (cyp19a1b-GFP) zebrafish embryos.

    Science.gov (United States)

    Brion, François; Le Page, Yann; Piccini, Benjamin; Cardoso, Olivier; Tong, Sok-Keng; Chung, Bon-chu; Kah, Olivier

    2012-01-01

    The tg(cyp19a1b-GFP) transgenic zebrafish expresses GFP (green fluorescent protein) under the control of the cyp19a1b gene, encoding brain aromatase. This gene has two major characteristics: (i) it is only expressed in radial glial progenitors in the brain of fish and (ii) it is exquisitely sensitive to estrogens. Based on these properties, we demonstrate that natural or synthetic hormones (alone or in binary mixture), including androgens or progestagens, and industrial chemicals induce a concentration-dependent GFP expression in radial glial progenitors. As GFP expression can be quantified by in vivo imaging, this model presents a very powerful tool to screen and characterize compounds potentially acting as estrogen mimics either directly or after metabolization by the zebrafish embryo. This study also shows that radial glial cells that act as stem cells are direct targets for a large panel of endocrine disruptors, calling for more attention regarding the impact of environmental estrogens and/or certain pharmaceuticals on brain development. Altogether these data identify this in vivo bioassay as an interesting alternative to detect estrogen mimics in hazard and risk assessment perspective.

  20. Prediction of mixture toxicity from the hormesis of a single chemical: A case study of combinations of antibiotics and quorum-sensing inhibitors with gram-negative bacteria.

    Science.gov (United States)

    Wang, Ting; Wang, Dali; Lin, Zhifen; An, Qingqing; Yin, Chunsheng; Huang, Qinghui

    2016-05-01

    The 50% effect level of a single chemical in the real environment is almost impossible to determine at the low exposure concentration, and the prediction of the concentration of a mixture at the 50% effect level from the concentration of a single chemical at the low effect level is even more difficult. The current literature does not address this problem. Thus, to determine solutions for this question, single/mixture chronic toxicities of sulfonamides (SAs) and quorum-sensing inhibitors (QSIs) were determined using Gram-negative bacteria (Vibrio fischeri and E. coli.) and Gram-positive bacteria (B. subtilis) as the target organisms. The results showed that the joint effects of SAs and QSIs were primarily antagonistic responses. In addition, the toxicity mechanisms of mixtures of SAs and QSIs were investigated further, and the results revealed that the chronic joint effects were primarily an antagonistic response due to the QSI competing against acyl-homoserine lactones (AHL) for luxR in V. fischeri and SdiA in E. coli generated by the SAs, leading to negative effects exerted by the QSI-luxR or QSI-SdiA complexes on luxI in V. fischeri or FtsZ in E. coli. This phenomenon eventually weakened the stimulatory effect caused by the SAs. Based on the mixture toxicity mechanism, the relationship between the mixture toxicity and the simulation effect was formulated.

  1. Using molecular docking between organic chemicals and lipid membrane to revise the well known octanol-water partition coefficient of the mixture.

    Science.gov (United States)

    Wang, Ting; Zhou, Xianghong; Wang, Dali; Yin, Daqiang; Lin, Zhifen

    2012-07-01

    The octanol-water partition coefficient of a mixture has been widely used to predict the baseline toxicity of non-polar narcotic chemical mixtures, since toxic effects are usually generated by multiple mixtures. However, it remains unclear whether the validity of log Kowmix can be demonstrated, because experimental methods cannot be used to determine this parameter. The invalidity and the further revision of log Kowmix were therefore studied by using molecular docking between non-polar narcotic chemicals and lipid membrane (E(binding)). The results show E(binding) is a feasible substitute parameter for log Kow because their relationship is linear. Based on a molecular docking and QSAR model, a new calculated method of log Kowmix was proposed as follows: log(Kowmix)=∑x(i)log Kowi. Comparison of this new method with the established methods demonstrates the invalidity of the latter, and therefore the former is suggested to be used to calculate the log Kowmix of organic chemical mixtures.

  2. Toxicity of proton-metal mixtures in the field: Linking stream macroinvertebrate species diversity to chemical speciation and bioavailability

    Energy Technology Data Exchange (ETDEWEB)

    Stockdale, Anthony [Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LA1 4AP (United Kingdom); Tipping, Edward, E-mail: et@ceh.ac.uk [Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LA1 4AP (United Kingdom); Lofts, Stephen [Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LA1 4AP (United Kingdom); Ormerod, Stephen J. [Catchment Research Group, Cardiff School of Biosciences, Cardiff University, Cardiff CF10 3US (United Kingdom); Clements, William H. [Department of Fish, Wildlife, and Conservation Biology, Colorado State University, Fort Collins, CO 80523 (United States); Blust, Ronny [Ecophysiology, Biochemistry and Toxicology Group, Department of Biology, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp (Belgium)

    2010-10-01

    Understanding metal and proton toxicity under field conditions requires consideration of the complex nature of chemicals in mixtures. Here, we demonstrate a novel method that relates streamwater concentrations of cationic metallic species and protons to a field ecological index of biodiversity. The model WHAM-F{sub TOX} postulates that cation binding sites of aquatic macroinvertebrates can be represented by the functional groups of natural organic matter (humic acid), as described by the Windermere Humic Aqueous Model (WHAM6), and supporting field evidence is presented. We define a toxicity function (F{sub TOX}) by summing the products: (amount of invertebrate-bound cation) x (cation-specific toxicity coefficient, {alpha}{sub i}). Species richness data for Ephemeroptera, Plecoptera and Trichoptera (EPT), are then described with a lower threshold of F{sub TOX}, below which all organisms are present and toxic effects are absent, and an upper threshold above which organisms are absent. Between the thresholds the number of species declines linearly with F{sub TOX}. We parameterised the model with chemistry and EPT data for low-order streamwaters affected by acid deposition and/or abandoned mines, representing a total of 412 sites across three continents. The fitting made use of quantile regression, to take into account reduced species richness caused by (unknown) factors other than cation toxicity. Parameters were derived for the four most common or abundant cations, with values of {alpha}{sub i} following the sequence (increasing toxicity) H{sup +} < Al < Zn < Cu. For waters affected mainly by H{sup +} and Al, F{sub TOX} shows a steady decline with increasing pH, crossing the lower threshold near to pH 7. Competition effects among cations mean that toxicity due to Cu and Zn is rare at lower pH values, and occurs mostly between pH 6 and 8.

  3. Adverse Reproductive and Developmental Health Outcomes Following Prenatal Exposure to a Hydraulic Fracturing Chemical Mixture in Female C57Bl/6 Mice.

    Science.gov (United States)

    Kassotis, Christopher D; Bromfield, John J; Klemp, Kara C; Meng, Chun-Xia; Wolfe, Andrew; Zoeller, R Thomas; Balise, Victoria D; Isiguzo, Chiamaka J; Tillitt, Donald E; Nagel, Susan C

    2016-09-01

    Unconventional oil and gas operations using hydraulic fracturing can contaminate surface and groundwater with endocrine-disrupting chemicals. We have previously shown that 23 of 24 commonly used hydraulic fracturing chemicals can activate or inhibit the estrogen, androgen, glucocorticoid, progesterone, and/or thyroid receptors in a human endometrial cancer cell reporter gene assay and that mixtures can behave synergistically, additively, or antagonistically on these receptors. In the current study, pregnant female C57Bl/6 dams were exposed to a mixture of 23 commonly used unconventional oil and gas chemicals at approximately 3, 30, 300, and 3000 μg/kg·d, flutamide at 50 mg/kg·d, or a 0.2% ethanol control vehicle via their drinking water from gestational day 11 through birth. This prenatal exposure to oil and gas operation chemicals suppressed pituitary hormone concentrations across experimental groups (prolactin, LH, FSH, and others), increased body weights, altered uterine and ovary weights, increased heart weights and collagen deposition, disrupted folliculogenesis, and other adverse health effects. This work suggests potential adverse developmental and reproductive health outcomes in humans and animals exposed to these oil and gas operation chemicals, with adverse outcomes observed even in the lowest dose group tested, equivalent to concentrations reported in drinking water sources. These endpoints suggest potential impacts on fertility, as previously observed in the male siblings, which require careful assessment in future studies.

  4. Chemical potential and internal energy of the noninteracting Fermi gas in fractional-dimensional space

    Indian Academy of Sciences (India)

    S Panda; B K Panda

    2010-09-01

    Chemical potential and internal energy of a noninteracting Fermi gas at low temperature are evaluated using the Sommerfeld method in the fractional-dimensional space. When temperature increases, the chemical potential decreases below the Fermi energy for any dimension equal to 2 and above due to the small entropy, while it increases above the Fermi energy for dimensions below 2 as a result of high entropy. The ranges of validity of the truncated series expansions of these quantities are extended from low to intermediate temperature regime as well as from high to relatively low density regime by using the Pad ́e approximant technique.

  5. Mixture risk assessment: a case study of Monsanto experiences.

    Science.gov (United States)

    Nair, R S; Dudek, B R; Grothe, D R; Johannsen, F R; Lamb, I C; Martens, M A; Sherman, J H; Stevens, M W

    1996-01-01

    Monsanto employs several pragmatic approaches for evaluating the toxicity of mixtures. These approaches are similar to those recommended by many national and international agencies. When conducting hazard and risk assessments, priority is always given to using data collected directly on the mixture of concern. To provide an example of the first tier of evaluation, actual data on acute respiratory irritation studies on mixtures were evaluated to determine whether the principle of additivity was applicable to the mixture evaluated. If actual data on the mixture are unavailable, extrapolation across similar mixtures is considered. Because many formulations are quite similar in composition, the toxicity data from one mixture can be extended to a closely related mixture in a scientifically justifiable manner. An example of a family of products where such extrapolations have been made is presented to exemplify this second approach. Lastly, if data on similar mixtures are unavailable, data on component fractions are used to predict the toxicity of the mixture. In this third approach, process knowledge and scientific judgement are used to determine how the known toxicological properties of the individual fractions affect toxicity of the mixture. Three examples of plant effluents where toxicological data on fractions were used to predict the toxicity of the mixture are discussed. The results of the analysis are used to discuss the predictive value of each of the above mentioned toxicological approaches for evaluating chemical mixtures.

  6. Use of pruned computational neural networks for processing the response of oscillating chemical reactions with a view to analyzing nonlinear multicomponent mixtures.

    Science.gov (United States)

    Hervás, C; Toledo, R; Silva, M

    2001-01-01

    The suitability of pruned computational neural networks (CNNs) for resolving nonlinear multicomponent systems involving synergistic effects by use of oscillating chemical reaction-based methods implemented using the analyte pulse perturbation technique is demonstrated. The CNN input data used for this purpose are estimates provided by the Levenberg-Marquardt method in the form of a three-parameter Gaussian curve associated with the singular profile obtained when the oscillating system is perturbed by an analyte mixture. The performance of the proposed method was assessed by applying it to the resolution of mixtures of pyrogallol and gallic acid based on their perturbating effect on a classical oscillating chemical system, viz. the Belousov-Zhabotinskyi reaction. A straightforward network topology (3:3:2, with 18 connections after pruning) allowed the resolution of mixtures of the two analytes in concentration ratios from 1:7 to 6:2 with a standard error of prediction for the testing set of 4.01 and 8.98% for pyrogallol and gallic acid, respectively. The reduced dimensions of the selected CNN architecture allowed a mathematical transformation of the input vector into the output one that can be easily implemented via software. Finally, the suitability of response surface analysis as an alternative to CNNs was also tested. The results were poor (relative errors were high), which confirms that properly selected pruned CNNs are effective tools for solving the analytical problem addressed in this work.

  7. International Frameworks Dealing with Human Risk Assessment of Combined Exposure to Multiple Chemicals

    Directory of Open Access Journals (Sweden)

    European Food Safety Authority

    2013-07-01

    Full Text Available The development of harmonised terminology and frameworks for the human risk assessment of combined exposure to multiple chemicals (“chemical mixtures” is an important area for EFSA and a number of activities have already been undertaken, i.e. in the fields of pesticides and contaminants. The first step prior to a risk assessment of combined exposure to multiple chemicals is problem formulation defining the relevant exposure, hazard and population to be considered. In practice, risk assessment of multiple chemicals is conducted using a tiered approach for exposure assessment, hazard assessment and risk characterisation. Higher tiers require increasing knowledge about the group of chemicals under assessment and the tiers can range from tier 0 (default values, data poor situation to tier 3 (full probabilistic models. This scientific report reviews the terminology, methodologies and frameworks developed by national and international agencies for the human risk assessment of combined exposure to multiple chemicals and provides recommendations for future activities at EFSA in this area.

  8. The substitution of hazardous chemicals in the international context - Opportunity for promoting sustainable chemistry

    DEFF Research Database (Denmark)

    Weber, R.; Lissner, L.; Fantke, Peter

    in particular in developing and transition countries do not know about more sustainable and green alternatives for a chemical in a particular application. Methodologies and tools are, hence, needed for the communication and dissemination of information on more sustainable alternatives. The substitution...... and phase-out of hazardous chemicals, such as persistent organic pollutants (POPs), on international level like under the Stockholm Convention, might provide one promising mechanism to mainstream more sustainable and greener chemicals and other alternative solutions aiming at eliminating or at least......-Phase-Out a publication has been developed compiling information on POPs-phase out and alternatives. In the conclusions and recommendation of this document “Sustainable and Green Chemistry” is highlighted as a guiding principle for alternatives assessment. This could be an entry point of Sustainable Chemistry...

  9. BEHAVIOR OF SURFACTANT MIXTURES AT SOLID/LIQUID AND OIL/LIQUID INTERFACES IN CHEMICAL FLOODING SYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    Prof. P. Somasundaran

    2002-09-30

    The aim of the project is to develop and evaluate efficient novel surfactant mixtures for enhanced oil recovery. Surfactant loss by adsorption or precipitation depends to a great extent on the type of surfactant complexes and aggregates formed. Such information as well as techniques to generate the information is lacking currently particularly for surfactant mixtures and surfactant/polymer systems. A novel analytical centrifuge application is explored during the last period to generate information on structures-performance relationship for different surfactant aggregates in solution and, in turn, at interfaces. To use analytical untracentrifuge for surfactant mixtures, information on partial specific volumes of single surfactants and their mixtures is required. Towards this purpose, surface tension and density measurements were performed to determine critical micellar concentrations (cmc), partial specific volumes of n-dodecyl-{beta}-Dmaltoside (DM), nonyl phenol ethoxylated decyl ether (NP-10) and their 1:1 mixtures at 25 C. Durchschlag's theoretical calculation method was adopted to calculate the partial specific volumes. Effects of temperature and mixing, as well as methods used for estimation on micellization and partial specific volumes were studied during the current period. Surface tension results revealed no interaction between the two surfactants in mixed micelles. Partial specific volume measurements also indicated no interaction in mixed micelles. Maximum adsorption density, area per molecule and free energy of micellization were also calculated. Partial specific volumes were estimated by two experimental methods: d{sub {rho}}/dc and V{sub {sigma}}. The difference between the results of using the two methods is within 0.5% deviation. It was found that the partial specific volume is concentration dependent and sensitive to changes in temperature. The information generated in this study will be used for the study of surfactant aggregate mass

  10. An in vivo animal study assessing long-term changes in hypothalamic cytokines following perinatal exposure to a chemical mixture based on Arctic maternal body burden

    Directory of Open Access Journals (Sweden)

    Li Nanqin

    2011-07-01

    Full Text Available Abstract Background The geographic distribution of environmental toxins is generally not uniform, with certain northern regions showing a particularly high concentration of pesticides, heavy metals and persistent organic pollutants. For instance, Northern Canadians are exposed to high levels of persistent organic pollutants like polychlorinated biphenyls (PCB, organochlorine pesticides (OCs and methylmercury (MeHg, primarily through country foods. Previous studies have reported associations between neuronal pathology and exposure to such toxins. The present investigation assessed whether perinatal exposure (gestation and lactation of rats to a chemical mixture (27 constituents comprised of PCBs, OCs and MeHg based on Arctic maternal exposure profiles at concentrations near human exposure levels, would affect brain levels of several inflammatory cytokines Methods Rats were dosed during gestation and lactation and cytokine levels were measured in the brains of offspring at five months of age. Hypothalamic cytokine protein levels were measured with a suspension-based array system and differences were determined using ANOVA and post hoc statistical tests. Results The early life PCB treatment alone significantly elevated hypothalamic interleukin-6 (IL-6 levels in rats at five months of age to a degree comparable to that of the entire chemical mixture. Similarly, the full mixture (and to a lesser degree PCBs alone elevated levels of the pro-inflammatory cytokine, IL-1b, as well as the anti-inflammatory cytokine, IL-10. The full mixture of chemicals also moderately increased (in an additive fashion hypothalamic levels of the pro-inflammatory cytokines, IL-12 and tumor necrosis factor (TNF-α. Challenge with bacterial endotoxin at adulthood generally increased hypothalamic levels to such a degree that differences between the perinatally treated chemical groups were no longer detectable. Conclusions These data suggest that exposure at critical

  11. Heat transfer and pressure drop performance of smooth and internally finned tubes with oil and refrigerant 22 mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Schlager, L.M. (Indiana-Purdue Univ., Ft. Wayne, IN (US)); Pate, M.B. (Iowa State Univ., Ames, IA (US)); Bergles, A.E. (Rensselaer Polytechnic Inst., Troy, NY (US))

    1989-01-01

    The overall performance of a smooth tube and two augmented tubes is compared by using an enhancement performance ratio, defined as the ratio of heat transfer enhancement to pressure drop increase. The augmented tubes are compared to the smooth tube with pure R-22 and with mixtures of R-22 plus 150-or 300-SUS naphthenic mineral oil. Additionally, the performance of all three tubes with refrigerant-oil mixtures is compared to performance of the same tube with pure refrigerant. Various oil concentrations up to 5% by weight were tested and mass flux was varied from 92,000 to 294,000 lb/h{circle dot}ft{sup 2} (125 to 400 kg/m{sup 2}{circle dot}s). Nominal evaporation conditions were 37{degrees}F(3{degrees}C) with inlet and outlet qualities of 15% and 85%, respectively. The condensation conditions were 105{degrees}F (41{degrees}C) with inlet and outlet qualities of 85% and 15%, respectively. The enhancement performance ratio of the micro-fin tube is consistently higher than that of the low-fin tube with either pure refrigerant or refrigerant-oil mixtures. With pure refrigerant, the enhancement performance ratio of the augmented tubes is generally greater than unity, indicating improved performance relative to a smooth tube.

  12. The Effect of Molecular Conformation on the Accuracy of Theoretical (1)H and (13)C Chemical Shifts Calculated by Ab Initio Methods for Metabolic Mixture Analysis.

    Science.gov (United States)

    Chikayama, Eisuke; Shimbo, Yudai; Komatsu, Keiko; Kikuchi, Jun

    2016-04-14

    NMR spectroscopy is a powerful method for analyzing metabolic mixtures. The information obtained from an NMR spectrum is in the form of physical parameters, such as chemical shifts, and construction of databases for many metabolites will be useful for data interpretation. To increase the accuracy of theoretical chemical shifts for development of a database for a variety of metabolites, the effects of sets of conformations (structural ensembles) and the levels of theory on computations of theoretical chemical shifts were systematically investigated for a set of 29 small molecules in the present study. For each of the 29 compounds, 101 structures were generated by classical molecular dynamics at 298.15 K, and then theoretical chemical shifts for 164 (1)H and 123 (13)C atoms were calculated by ab initio quantum chemical methods. Six levels of theory were used by pairing Hartree-Fock, B3LYP (density functional theory), or second order Møller-Plesset perturbation with 6-31G or aug-cc-pVDZ basis set. The six average fluctuations in the (1)H chemical shift were ±0.63, ± 0.59, ± 0.70, ± 0.62, ± 0.75, and ±0.66 ppm for the structural ensembles, and the six average errors were ±0.34, ± 0.27, ± 0.32, ± 0.25, ± 0.32, and ±0.25 ppm. The results showed that chemical shift fluctuations with changes in the conformation because of molecular motion were larger than the differences between computed and experimental chemical shifts for all six levels of theory. In conclusion, selection of an appropriate structural ensemble should be performed before theoretical chemical shift calculations for development of an accurate database for a variety of metabolites.

  13. Differentiation of Chemical Components in a Binary Solvent Vapor Mixture Using Carbon/Polymer Composite-Based Chemiresistors

    Energy Technology Data Exchange (ETDEWEB)

    Patel, Sanjay V.; Jenkins, Mark W.; Hughes, Robert C.; Yelton, W. Graham; Ricco, Antonio J.

    1999-07-19

    We demonstrate a ''universal solvent sensor'' constructed from a small array of carbon/polymer composite chemiresistors that respond to solvents spanning a wide range of Hildebrand volubility parameters. Conductive carbon particles provide electrical continuity in these composite films. When the polymer matrix absorbs solvent vapors, the composite film swells, the average separation between carbon particles increases, and an increase in film resistance results, as some of the conduction pathways are broken. The adverse effects of contact resistance at high solvent concentrations are reported. Solvent vapors including isooctane, ethanol, dlisopropyhnethylphosphonate (DIMP), and water are correctly identified (''classified'') using three chemiresistors, their composite coatings chosen to span the full range of volubility parameters. With the same three sensors, binary mixtures of solvent vapor and water vapor are correctly classified, following classification, two sensors suffice to determine the concentrations of both vapor components. Polyethylene vinylacetate and polyvinyl alcohol (PVA) are two such polymers that are used to classify binary mixtures of DIMP with water vapor; the PVA/carbon-particle-composite films are sensitive to less than 0.25{degree}A relative humidity. The Sandia-developed VERI (Visual-Empirical Region of Influence) technique is used as a method of pattern recognition to classify the solvents and mixtures and to distinguish them from water vapor. In many cases, the response of a given composite sensing film to a binary mixture deviates significantly from the sum of the responses to the isolated vapor components at the same concentrations. While these nonlinearities pose significant difficulty for (primarily) linear methods such as principal components analysis, VERI handles both linear and nonlinear data with equal ease. In the present study the maximum speciation accuracy is achieved by an array

  14. Final report on international comparison EURO.QM-S5/1166: Carbon dioxide mixtures in nitrogen

    Science.gov (United States)

    Dias, Florbela A.; Baptista, Gonçalo; Rakowska, Agata; Chye, Teo Chin; Beng Keat, Teo; Cieciora, Darek; Augusto, Cristiane; Lin, Tsai-Yin; Niederhauser, Bernhard; Fükö, Judit; Sinweeruthai, Ratirat; Johri, Prabha; Akcadag, Fatma; Tarhan, Tanil; van der Veen, Adriaan M. H.; van Wijk, Janneke

    2013-01-01

    This supplementary comparison is designed to test the capabilities of the participants to measure and certify carbon dioxide in nitrogen, and to provide supporting evidence for the CMCs of institutes for carbon dioxide. Indeed this comparison aims to demonstrate the capabilities of IPQ in the production of primary gas mixtures of carbon dioxide in nitrogen and for the participant laboratories to demonstrate their capabilities on certifying primary gas mixtures of percent levels of carbon dioxide in nitrogen. Moreover, a number of NMIs had already participated in the key comparison CCQM-K52, but in a lower range. This EURAMET comparison offers an opportunity to the laboratories to submit CMC in a higher range. In this comparison the laboratories analysed the gas mixtures that are gravimetrically produced and analyzed by IPQ. Each cylinder had its own reference value calculated from the gravimetric preparation. The pressure in the cylinders was approximately 10 MPa; aluminum cylinders of 5 dm3 nominal volume were used. This comparison provides evidence in support of CMCs for carbon dioxide within the range of 1.0 × 10-2 mol/mol to 20.0 × 10-2 mol/mol in a nitrogen/air balance. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by EURAMET, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  15. Assessing the carcinogenic potential of low-dose exposures to chemical mixtures in the environment: focus on the cancer hallmark of tumor angiogenesis.

    Science.gov (United States)

    Hu, Zhiwei; Brooks, Samira A; Dormoy, Valérian; Hsu, Chia-Wen; Hsu, Hsue-Yin; Lin, Liang-Tzung; Massfelder, Thierry; Rathmell, W Kimryn; Xia, Menghang; Al-Mulla, Fahd; Al-Temaimi, Rabeah; Amedei, Amedeo; Brown, Dustin G; Prudhomme, Kalan R; Colacci, Annamaria; Hamid, Roslida A; Mondello, Chiara; Raju, Jayadev; Ryan, Elizabeth P; Woodrick, Jordan; Scovassi, A Ivana; Singh, Neetu; Vaccari, Monica; Roy, Rabindra; Forte, Stefano; Memeo, Lorenzo; Salem, Hosni K; Lowe, Leroy; Jensen, Lasse; Bisson, William H; Kleinstreuer, Nicole

    2015-06-01

    One of the important 'hallmarks' of cancer is angiogenesis, which is the process of formation of new blood vessels that are necessary for tumor expansion, invasion and metastasis. Under normal physiological conditions, angiogenesis is well balanced and controlled by endogenous proangiogenic factors and antiangiogenic factors. However, factors produced by cancer cells, cancer stem cells and other cell types in the tumor stroma can disrupt the balance so that the tumor microenvironment favors tumor angiogenesis. These factors include vascular endothelial growth factor, endothelial tissue factor and other membrane bound receptors that mediate multiple intracellular signaling pathways that contribute to tumor angiogenesis. Though environmental exposures to certain chemicals have been found to initiate and promote tumor development, the role of these exposures (particularly to low doses of multiple substances), is largely unknown in relation to tumor angiogenesis. This review summarizes the evidence of the role of environmental chemical bioactivity and exposure in tumor angiogenesis and carcinogenesis. We identify a number of ubiquitous (prototypical) chemicals with disruptive potential that may warrant further investigation given their selectivity for high-throughput screening assay targets associated with proangiogenic pathways. We also consider the cross-hallmark relationships of a number of important angiogenic pathway targets with other cancer hallmarks and we make recommendations for future research. Understanding of the role of low-dose exposure of chemicals with disruptive potential could help us refine our approach to cancer risk assessment, and may ultimately aid in preventing cancer by reducing or eliminating exposures to synergistic mixtures of chemicals with carcinogenic potential.

  16. Proceedings of the frst joint american chemical society agricultural and food chemistry division – american chemical society international chemical sciences chapter in Thailand symposium on agricultural and food chemistry

    Science.gov (United States)

    This Proceedings is a compilation of papers from contributed oral and poster presentations presented at the first joint symposium organized by the American Chemical Society Agricultural and Food Chemistry Division and the American Chemical Society International Chemical Sciences Chapter in Thailand ...

  17. Assessing occupational exposure to chemicals in an international epidemiological study of brain tumours.

    Science.gov (United States)

    van Tongeren, Martie; Kincl, Laurel; Richardson, Lesley; Benke, Geza; Figuerola, Jordi; Kauppinen, Timo; Lakhani, Ramzan; Lavoué, Jérôme; McLean, Dave; Plato, Nils; Cardis, Elisabeth

    2013-06-01

    The INTEROCC project is a multi-centre case-control study investigating the risk of developing brain cancer due to occupational chemical and electromagnetic field exposures. To estimate chemical exposures, the Finnish Job Exposure Matrix (FINJEM) was modified to improve its performance in the INTEROCC study and to address some of its limitations, resulting in the development of the INTEROCC JEM. An international team of occupational hygienists developed a crosswalk between the Finnish occupational codes used in FINJEM and the International Standard Classification of Occupations 1968 (ISCO68). For ISCO68 codes linked to multiple Finnish codes, weighted means of the exposure estimates were calculated. Similarly, multiple ISCO68 codes linked to a single Finnish code with evidence of heterogeneous exposure were refined. One of the key time periods in FINJEM (1960-1984) was split into two periods (1960-1974 and 1975-1984). Benzene exposure estimates in early periods were modified upwards. The internal consistency of hydrocarbon exposures and exposures to engine exhaust fumes was improved. Finally, exposure to polycyclic aromatic hydrocarbon and benzo(a)pyrene was modified to include the contribution from second-hand smoke. The crosswalk ensured that the FINJEM exposure estimates could be applied to the INTEROCC study subjects. The modifications generally resulted in an increased prevalence of exposure to chemical agents. This increased prevalence of exposure was not restricted to the lowest categories of cumulative exposure, but was seen across all levels for some agents. Although this work has produced a JEM with important improvements compared to FINJEM, further improvements are possible with the expansion of agents and additional external data.

  18. Chemical imaging techniques for the analysis of complex mixtures: New application to the characterization of ritual matters on African wooden statuettes

    Energy Technology Data Exchange (ETDEWEB)

    Mazel, Vincent [Centre de Recherche et de Restauration des musees de France (C2RMF), CNRS UMR 171, Palais du Louvre, Porte des Lions 14, quai Francois Mitterrand, 75001 Paris (France); Richardin, Pascale [Centre de Recherche et de Restauration des musees de France (C2RMF), CNRS UMR 171, Palais du Louvre, Porte des Lions 14, quai Francois Mitterrand, 75001 Paris (France)]. E-mail: pascale.richardin@culture.gouv.fr; Touboul, David [Laboratoire de Spectrometrie de Masse, Institut de Chimie des Substances Naturelles, CNRS UPR 2301, Avenue de la Terrasse, 91198 Gif-sur-Yvette (France); Brunelle, Alain [Laboratoire de Spectrometrie de Masse, Institut de Chimie des Substances Naturelles, CNRS UPR 2301, Avenue de la Terrasse, 91198 Gif-sur-Yvette (France); Walter, Philippe [Centre de Recherche et de Restauration des musees de France (C2RMF), CNRS UMR 171, Palais du Louvre, Porte des Lions 14, quai Francois Mitterrand, 75001 Paris (France); Laprevote, Olivier [Laboratoire de Spectrometrie de Masse, Institut de Chimie des Substances Naturelles, CNRS UPR 2301, Avenue de la Terrasse, 91198 Gif-sur-Yvette (France)

    2006-06-07

    Chemical imaging techniques, based on the combination of microscopy and spectroscopy, are well suited to study both the composition and the spatial organization of heterogeneous complex mixtures of organic and mineral matter. Time-of-flight secondary ion mass spectrometry (ToF-SIMS), followed by scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX) and Fourier transform infrared microscopy (FTIR microscopy) have been applied to non-destructive analysis of micro-samplings of ritual matters deposited on the surface of African wooden statuettes. With a very careful preparation, using ultramicrotomy on embedded samples, it was possible to perform successively all the measurements on a single fragment. Comparison and superposition of the different chemical images, obtained on a sample from a significant actual artefact, have allowed us to identify minerals (clays, quartz and calcium carbonate), proteins, starch, urate salts and lipids and to map their spatial distribution.

  19. Chemical reaction rates and non-equilibrium pressure of reacting gas mixtures in the state-to-state approach

    Science.gov (United States)

    Kustova, Elena V.; Kremer, Gilberto M.

    2014-12-01

    Viscous gas flows with vibrational relaxation and chemical reactions in the state-to-state approach are analyzed. A modified Chapman-Enskog method is used for the determination of chemical reaction and vibrational transition rates and non-equilibrium pressure. Constitutive equations depend on the thermodynamic forces: velocity divergence and chemical reaction/transition affinity. As an application, N2 flow with vibrational relaxation across a shock wave is investigated. Two distinct processes occur behind the shock: for small values of the distance the affinity is large and vibrational relaxation is in its initial stage; for large distances the affinity is small and the chemical reaction is in its final stage. The affinity contributes more to the transition rate than the velocity divergence and the effect of these two contributions are more important for small distances from the shock front. For the non-equilibrium pressure, the term associated with the bulk viscosity increases by a small amount the hydrostatic pressure.

  20. Internal Domains of Natural Porous Media Revealed: Critical Locations for Transport, Storage, and Chemical Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Zachara, John M.; Brantley, Susan L.; Chorover, Jon D.; Ewing, Robert P.; Kerisit, Sebastien N.; Liu, Chongxuan; Perfect, E.; Rother, Gernot; Stack, Andrew G.

    2016-03-16

    Internal pore domains exist within rocks, lithic fragments, subsurface sediments and soil aggregates. These domains, which we term internal domains in porous media (IDPM), contain a significant fraction of their porosity as nanopores, dominate the reactive surface area of diverse porous media types, and are important locations for chemical reactivity and hydrocarbon storage. Traditionally difficult to interrogate, advances in instrumentation and imaging methods are providing new insights on the physical structures and chemical attributes of IDPM. In this review we: discuss analytical methods to characterize IDPM, evaluate what has been learned about their size distributions, connectivity, and extended structures; determine whether they exhibit unique chemical reactivity; and assess potential for their inclusion in reactive transport models. Three key findings are noteworthy. 1) A combination of methods now allows complete characterization of the porosity spectrum of natural materials and its connectivity; while imaging microscopies are providing three dimensional representations of the interconnected pore network. 2) Chemical reactivity in pores <10 nm is expected to be different from micro and macropores, yet research performed to date is inconclusive on the nature, direction, and magnitude of effect. 3) Existing continuum reactive transport models treat IDPM as a sub-grid feature with average, empirical, scale-dependent parameters; and are not formulated to include detailed information on pore networks. Overall we find that IDPM are key features controlling hydrocarbon release from shales in hydrofracking systems, organic matter stabilization and recalcitrance in soil, weathering and soil formation, and long term inorganic and organic contaminant behavior in the vadose zone and groundwater. We conclude with an assessment of impactful research opportunities to advance understanding of IDPM, and to incorporate their important effects in reactive transport models

  1. Quantitative analysis of liver GST-P foci promoted by a chemical mixture of hexachlorobenzene and PCB 126: implication of size-dependent cellular growth kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Yasong [Colorado State University, Quantitative and Computational Toxicology Group, Department of Environmental and Radiological Health Sciences, Fort Collins, CO (United States); Translational Pharmacology Group, PDM, Pfizer Inc, Groton, CT (United States); Lohitnavy, Manupat; Lohitnavy, Ornrat; Eickman, Elizabeth; Gerjevic, Lisa; Yang, Raymond S.H. [Colorado State University, Quantitative and Computational Toxicology Group, Department of Environmental and Radiological Health Sciences, Fort Collins, CO (United States); Reddy, Micaela [DMPK Group, Preclinical Sciences, Roche Palo Alto LLC, CA (United States); Ashley, Amanda [Colorado State University, Department of Cell and Molecular Biology, Fort Collins, CO (United States); Xu, Yihua [University of Wisconsin, McArdle Laboratory for Cancer Research, Madison, WI (United States); Conolly, Rory B. [USEPA, National Center for Computational Toxicology, Research Triangle Park, NC (United States)

    2008-02-15

    The objectives of this study were twofold: (1) evaluating the carcinogenic potential of the mixture of two persistent environmental pollutants, hexachlorobenzene (HCB) and 3,3',4,4',5-pentachlorobiphenyl (PCB 126), in an initiation-promotion bioassay involving the development of {pi} glutathione S-transferase (GST-P) liver foci, and (2) analyzing the GST-P foci data using a biologically-based computer model (i.e., clonal growth model) with an emphasis on the effect of focal size on the growth kinetics of initiated cells. The 8-week bioassay involved a series of treatments of initiator, two-thirds partial hepatectomy, and daily oral gavage of the mixture of two doses in male F344 rats. The mixture treatment significantly increased liver GST-P foci development, indicating carcinogenic potential of this mixture. Our clonal growth model was developed to simulate the appearance and development of initiated GST-P cells in the liver over time. In the model, the initiated cells were partitioned into two subpopulations with the same division rate but different death rates. Each subpopulation was further categorized into single cells, mini- (2-11 cells), medium- (12-399 cells), and large-foci (>399 cells) with different growth kinetics. Our modeling suggested that the growth of GST-P foci is size-dependent; in general, the larger the foci, the higher the rate constants of division and death. In addition, the modeling implied that the two doses promoted foci development in different manners even though the experimental foci data appeared to be similar between the two doses. This study further illustrated how clonal growth modeling may facilitate our understanding in chemical carcinogenic process. (orig.)

  2. An assessment of the model of concentration addition for predicting the estrogenic activity of chemical mixtures in wastewater treatment works effluents.

    Science.gov (United States)

    Thorpe, Karen L; Gross-Sorokin, Melanie; Johnson, Ian; Brighty, Geoff; Tyler, Charles R

    2006-04-01

    The effects of simple mixtures of chemicals, with similar mechanisms of action, can be predicted using the concentration addition model (CA). The ability of this model to predict the estrogenic effects of more complex mixtures such as effluent discharges, however, has yet to be established. Effluents from 43 U.K. wastewater treatment works were analyzed for the presence of the principal estrogenic chemical contaminants, estradiol, estrone, ethinylestradiol, and nonylphenol. The measured concentrations were used to predict the estrogenic activity of each effluent, employing the model of CA, based on the relative potencies of the individual chemicals in an in vitro recombinant yeast estrogen screen (rYES) and a short-term (14-day) in vivo rainbow trout vitellogenin induction assay. Based on the measured concentrations of the four chemicals in the effluents and their relative potencies in each assay, the calculated in vitro and in vivo responses compared well and ranged between 3.5 and 87 ng/L of estradiol equivalents (E2 EQ) for the different effluents. In the rYES, however, the measured E2 EQ concentrations in the effluents ranged between 0.65 and 43 ng E2 EQ/L, and they varied against those predicted by the CA model. Deviations in the estimation of the estrogenic potency of the effluents by the CA model, compared with the measured responses in the rYES, are likely to have resulted from inaccuracies associated with the measurement of the chemicals in the extracts derived from the complex effluents. Such deviations could also result as a consequence of interactions between chemicals present in the extracts that disrupted the activation of the estrogen response elements in the rYES. E2 EQ concentrations derived from the vitellogenic response in fathead minnows exposed to a series of effluent dilutions were highly comparable with the E2 EQ concentrations derived from assessments of the estrogenic potency of these dilutions in the rYES. Together these data support the

  3. Chemical reaction rates and non-equilibrium pressure of reacting gas mixtures in the state-to-state approach

    Energy Technology Data Exchange (ETDEWEB)

    Kustova, Elena V., E-mail: e.kustova@spbu.ru [Department of Mathematics and Mechanics, Saint Petersburg State University, 198504 Universitetskiy pr. 28, Saint Petersburg (Russian Federation); Kremer, Gilberto M., E-mail: kremer@fisica.ufpr.br [Departamento de Física, Universidade Federal do Paraná, Caixa Postal 19044, 81531-980 Curitiba (Brazil)

    2014-12-05

    Highlights: • State-to-state approach for coupled vibrational relaxation and chemical reactions. • Self-consistent model for rates of non-equilibrium reactions and energy transitions. • In viscous flows mass action law is violated. • Cross coupling between reaction rates and non-equilibrium pressure in viscous flow. • Results allow implementing the state-to-state approach for viscous flow simulations. - Abstract: Viscous gas flows with vibrational relaxation and chemical reactions in the state-to-state approach are analyzed. A modified Chapman–Enskog method is used for the determination of chemical reaction and vibrational transition rates and non-equilibrium pressure. Constitutive equations depend on the thermodynamic forces: velocity divergence and chemical reaction/transition affinity. As an application, N{sub 2} flow with vibrational relaxation across a shock wave is investigated. Two distinct processes occur behind the shock: for small values of the distance the affinity is large and vibrational relaxation is in its initial stage; for large distances the affinity is small and the chemical reaction is in its final stage. The affinity contributes more to the transition rate than the velocity divergence and the effect of these two contributions are more important for small distances from the shock front. For the non-equilibrium pressure, the term associated with the bulk viscosity increases by a small amount the hydrostatic pressure.

  4. High sensitivity stand-off detection and quantification of chemical mixtures using an active coherent laser spectrometer (ACLaS)

    Science.gov (United States)

    MacLeod, Neil A.; Weidmann, Damien

    2016-05-01

    High sensitivity detection, identification and quantification of chemicals in a stand-off configuration is a highly sought after capability across the security and defense sector. Specific applications include assessing the presence of explosive related materials, poisonous or toxic chemical agents, and narcotics. Real world field deployment of an operational stand-off system is challenging due to stringent requirements: high detection sensitivity, stand-off ranges from centimeters to hundreds of meters, eye-safe invisible light, near real-time response and a wide chemical versatility encompassing both vapor and condensed phase chemicals. Additionally, field deployment requires a compact, rugged, power efficient, and cost-effective design. To address these demanding requirements, we have developed the concept of Active Coherent Laser Spectrometer (ACLaS), which can be also described as a middle infrared hyperspectral coherent lidar. Combined with robust spectral unmixing algorithms, inherited from retrievals of information from high-resolution spectral data generated by satellitebased spectrometers, ACLaS has been demonstrated to fulfil the above-mentioned needs. ACLaS prototypes have been so far developed using quantum cascade lasers (QCL) and interband cascade lasers (ICL) to exploit the fast frequency tuning capability of these solid state sources. Using distributed feedback (DFB) QCL, demonstration and performance analysis were carried out on narrow-band absorbing chemicals (N2O, H2O, H2O2, CH4, C2H2 and C2H6) at stand-off distances up to 50 m using realistic non cooperative targets such as wood, painted metal, and bricks. Using more widely tunable external cavity QCL, ACLaS has also been demonstrated on broadband absorbing chemicals (dichloroethane, HFC134a, ethylene glycol dinitrate and 4-nitroacetanilide solid) and on complex samples mixing narrow-band and broadband absorbers together in a realistic atmospheric background.

  5. Chemical Composition of Aerosol Particles Emitted by a Passenger Car Engine Fueled by Ethanol/Gasoline Mixtures

    Science.gov (United States)

    Medrano, J. M.; Gross, D. S.; Dutcher, D. D.; Drayton, M.; Kittelson, D.; McMurry, P.

    2007-12-01

    With concerns of national security, climate change, and human health, many people have called for oil independence for the United States and for the creation of alternative fuels. Ethanol has been widely praised as a viable alternative to petroleum-based fuels, due to the fact that it can be produced locally. A great deal of work has been done to characterize the energy balance of ethanol production versus consumption, but there have been fewer studies of the environmental and health impacts of emissions from combustion of ethanol/gasoline mixtures such as those burned in the modern vehicle fleet. To study the particulate emissions from such fuels, different ethanol/gasoline fuel mixtures with 0, 20, 40, and 85% ethanol were burned in a dynamometer-mounted automobile engine. The engine exhaust was diluted and sampled with two aerosol Time-of-Flight Mass Spectrometers (TSI 3800 ATOFMS), sampling different particle size ranges (50-500 nm and 150-3000 nm, respectively), to measure size and composition of the emitted aerosol particles. A variety of other aerosol characterization techniques were also employed to determine the size distribution of the aerosol particles, the mass emission rate from the engine, and the concentration of polycyclic aromatic hydrocarbons (PAHs) and elemental carbon (EC) in the particle emissions. Here we will focus on results from the ATOFMS, which provides us with a particle size and mass spectra - for both negative and positive ions - for each particle that is sampled. Particles being emitted were found to contain primarily PAHs, elemental carbon (EC), nitrates, and sulfates. Particles were analyzed to investigate trends in particle composition as a function of fuel ethanol content, particle size, and for the types of particles emitted. A trend in particle type as a function of fuel ethanol content was evident in smaller particles, and trends in composition as a function of particle size were visible across the entire size range sampled.

  6. The use of superoxide mixtures as air-revitalization chemicals in hyperbaric, self-contained, closed-circuit breathing apparatus

    Science.gov (United States)

    Wood, P. C.; Wydeven, T.

    1985-01-01

    In portable breathing apparatus applications at 1 atm, potassium superoxide (KO2) has exhibited low-utilization efficiency of the available oxygen (O2) and diminished carbon dioxide-(CO2) scrubbing capacity caused by the formation of a fused, hydrated-hydroxide/carbonate product coating on the superoxide granules. In earlier work, it was discovered that granules fabricated from an intimate mixture of KO2 and calcium superoxide, Ca(O2)2, did not exhibit formation of a fused product coating and the utilization efficiency with respect to both O2 release and CO2 absorption was superior to KO2 granules when both types of granules were reacted with humidified CO2 under identified conditions. In the work described here, single pellets of KO2, KO2/Ca(O2), mixtures and commercially available KO2 tables and granules were reacted with a flow of humidified CO2 in helium at 1- and 10-atm total pressure and at an initial temperature of 40 C. In the 1-atm flow tests, the reaction rates and utilization efficiency of the KO2/Ca(O2)2 pellets were markedly superior to the KO2 pellets, tablets, and granules when the samples were reacted under identical conditions. However, at 10 atm, the rates of O2 release and CO2 absorption, as well as the utilization efficiencies of all the superoxide samples, were one-third to one-eighth of the values observed at 1 atm. The decrease in reaction performance at 10 atm compared to that at 1 atm has been attributed principally to the lower bulk diffusivity of the CO2 and H2O reactants in helium at the higher pressure and secondarily to the moderation of the reaction temperature caused by the higher heat capacity of the 10-atm helium.

  7. Spectral properties of mixtures of montmorillonite and dark grains - Implications for remote sensing minerals containing chemically and physically adsorbed water

    Science.gov (United States)

    Clark, R. N.

    1983-01-01

    The spectral properties from 0.4 to 3 microns of montmorillonite plus dark carbon grains (called opaques) of various sizes are studied as a function of the weight fraction of opaques present. The reflectance level and band depths of the 1.4-, 1.9-, 2.2-, and 2.8-micron water and/or OH absorption features are analyzed using derived empirical relationships and scattering theory. It is found that the absorption band depths and reflectance level are a very nonlinear function of the weight fraction of opaques present but can be predicted in many cases by simple scattering theory. The 2.8-micron bound water fundamental band is the most difficult absorption feature to suppress. The overtone absorptions are suppressed a greater amount than the fundamental but are still apparent even when 10-20 wt pct opaques are present. The relationships observed and the simple scattering theory presented show that quantitative compositional remote sensing studies are feasible for surfaces containing complex mineral mixtures.

  8. Investigation of Spark Ignition and Autoignition in Methane and Air Using Computational Fluid Dynamics and Chemical Reaction Kinetics. A numerical Study of Ignition Processes in Internal Combustion Engines

    Energy Technology Data Exchange (ETDEWEB)

    Nordrik, R.

    1993-12-01

    The processes in the combustion chamber of internal combustion engines have received increased attention in recent years because their efficiencies are important both economically and environmentally. This doctoral thesis studies the ignition phenomena by means of numerical simulation methods. The fundamental physical relations include flow field conservation equations, thermodynamics, chemical reaction kinetics, transport properties and spark modelling. Special attention is given to the inclusion of chemical kinetics in the flow field equations. Using his No Transport of Radicals Concept method, the author reduces the computational efforts by neglecting the transport of selected intermediate species. The method is validated by comparison with flame propagation data. A computational method is described and used to simulate spark ignition in laminar premixed methane-air mixtures and the autoignition process of a methane bubble surrounded by hot air. The spark ignition simulation agrees well with experimental results from the literature. The autoignition simulation identifies the importance of diffusive and chemical processes acting together. The ignition delay times exceed the experimental values found in the literature for premixed ignition delay, presumably because of the mixing process and lack of information on low temperature reactions in the skeletal kinetic mechanism. Transient turbulent methane jet autoignition is simulated by means of the KIVA-II code. Turbulent combustion is modelled by the Eddy Dissipation Concept. 90 refs., 81 figs., 3 tabs.

  9. Reducing CO{sub 2} emissions of internally heat-integrated distillation columns for separation of close boiling mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Gadalla, M. [Departament d' Engingeria Quimica, Universitat Rovira i Virgili, Paisos Catalans 26, 43007 Tarragona (Spain); Olujic, I.; Rijke, A. de; Jansens, P.J. [Laboratory for Process Equipment, TU Delft, Leeghwaterstraat 44, 2628 CA Delft (Netherlands)

    2006-10-15

    A model developed originally for crude oil distillation units has been applied to a standalone internally heat integrated distillation column (HIDiC) to evaluate emissions levels and to generate design options for direct carbon dioxide emissions reduction. Simulations indicate that for propylene-propane separation, an ideal (no reboiler) HIDiC enables a reduction in emissions of 83% and of 36%, compared to conventional and heat pump alternatives, respectively. Integrating a turbine to drive the compressor, in conjunction with a suitable fuel is the key to the minimization of the emissions associated with the operation of a HIDiC. Importantly, while substantial emission reductions are achieved, the process economics are improved. (author)

  10. Modelling the influence of inulin as a fat substitute in comminuted meat products on their physico-chemical characteristics and eating quality using a mixture design approach.

    Science.gov (United States)

    Keenan, Derek F; Resconi, Virginia C; Kerry, Joseph P; Hamill, Ruth M

    2014-03-01

    The effects of fat substitution using two commercial inulin products on the physico-chemical properties and eating quality of a comminuted meat product (breakfast sausage) were modelled using a specialised response surface experiment specially developed for mixtures. 17 treatments were assigned representing a different substitution level for fat with inulin. Sausages were formulated to contain pork shoulder, back fat/inulin, water, rusk and seasoning (44.3, 18.7, 27.5, 7 and 2.5% w/w). Composition, sensory, instrumental texture and colour characteristics were assessed. Fructan analysis showed that inulin was unaffected by heat or processing treatments. Models showed increasing inulin inclusions decreased cook loss (pinulin concentration, with panellists also scoring products containing inulin as less tender (pinulin to deliver a prebiotic health effect.

  11. Controlled chemical modification of the internal surface of photonic crystal fibers for application as biosensitive elements

    Science.gov (United States)

    Pidenko, Sergey A.; Burmistrova, Natalia A.; Pidenko, Pavel S.; Shuvalov, Andrey A.; Chibrova, Anastasiya A.; Skibina, Yulia S.; Goryacheva, Irina Y.

    2016-10-01

    Photonic crystal fibers (PCF) are one of the most promising materials for creation of constructive elements for bio-, drug and contaminant sensing based on unique optical properties of the PCF as effective nanosized optical signal collectors. In order to provide efficient and controllable binding of biomolecules, the internal surface of glass hollow core photonic crystal fibers (HC-PCF) has been chemically modified with silanol groups and functionalized with (3-aminopropyl) triethoxysilane (APTES). The shift of local maxima in the HC-PCF transmission spectrum has been selected as a signal for estimating the amount of silanol groups on the HC-PCF inner surface. The relationship between amount of silanol groups on the HC-PCF inner surface and efficiency of following APTES functionalization has been evaluated. Covalent binding of horseradish peroxidase (chosen as a model protein) on functionalized PCF inner surface has been performed successively, thus verifying the possibility of creating a biosensitive element.

  12. The role of NH3 and hydrocarbon mixtures in GaN pseudo-halide CVD: a quantum chemical study.

    Science.gov (United States)

    Gadzhiev, Oleg B; Sennikov, Peter G; Petrov, Alexander I; Kachel, Krzysztof; Golka, Sebastian; Gogova, Daniela; Siche, Dietmar

    2014-11-01

    The prospects of a control for a novel gallium nitride pseudo-halide vapor phase epitaxy (PHVPE) with HCN were thoroughly analyzed for hydrocarbons-NH3-Ga gas phase on the basis of quantum chemical investigation with DFT (B3LYP, B3LYP with D3 empirical correction on dispersion interaction) and ab-initio (CASSCF, coupled clusters, and multireference configuration interaction including MRCI+Q) methods. The computational screening of reactions for different hydrocarbons (CH4, C2H6, C3H8, C2H4, and C2H2) as readily available carbon precursors for HCN formation, potential chemical transport agents, and for controlled carbon doping of deposited GaN was carried out with the B3LYP method in conjunction with basis sets up to aug-cc-pVTZ. The gas phase intermediates for the reactions in the Ga-hydrocarbon systems were predicted at different theory levels. The located π-complexes Ga…C2H2 and Ga…C2H4 were studied to determine a probable catalytic activity in reactions with NH3. A limited influence of the carbon-containing atmosphere was exhibited for the carbon doping of GaN crystal in the conventional GaN chemical vapor deposition (CVD) process with hydrocarbons injected in the gas phase. Our results provide a basis for experimental studies of GaN crystal growth with C2H4 and C2H2 as auxiliary carbon reagents for the Ga-NH3 and Ga-C-NH3 CVD systems and prerequisites for reactor design to enhance and control the PHVPE process through the HCN synthesis.

  13. Mixtures and interactions

    NARCIS (Netherlands)

    Groten, J.P.

    2000-01-01

    Drinking water can be considered as a complex mixture that consists of tens, hundreds or thousands of chemicals of which the composition is qualitatively and quantitatively not fully known. From a public health point of view it is most relevant to answer the question of whether chemicals in drinking

  14. Influence of pressure and temperature on the physico-chemical properties of mobile phase mixtures commonly used in high-performance liquid chromatography.

    Science.gov (United States)

    Billen, Jeroen; Broeckhoven, Ken; Liekens, Anuschka; Choikhet, Konstantin; Rozing, Gerard; Desmet, Gert

    2008-11-07

    To fulfil the increasing demand for faster and more complex separations, modern HPLC separations are performed at ever higher pressures and temperatures. Under these operating conditions, it is no longer possible to safely assume the mobile phase fluid properties to be invariable of the governing pressures and temperatures, without this resulting in significantly deficient results. A detailed insight in the influence of pressure and temperature on the physico-chemical properties of the most commonly used liquid mobile phases: water-methanol and water-acetonitrile mixtures, therefore becomes very timely. Viscosity, isothermal compressibility and density were measured for pressures up to 1000 bar and temperatures up to 100 degrees C for the entire range of water-methanol and water-acetonitrile mixtures. The paper reports on two different viscosity values: apparent and real viscosities. The apparent viscosities represent the apparent flow resistance under high pressure referred to by the flow rates measured at atmospheric pressure. They are of great practical use, because the flow rates at atmospheric pressure are commonly stable and more easily measurable in a chromatographic setup. The real viscosities are those complying with the physical definition of viscosity and they are important from a fundamental point of view. By measuring the isothermal compressibility, the actual volumetric flow rates at elevated pressures and temperatures can be calculated. The viscosities corresponding to these flow rates are the real viscosities of the solvent under the given elevated pressure and temperature. The measurements agree very well with existing literature data, which mainly focus on pure water, methanol and acetonitrile and are only available for a limited range of temperatures and pressures. As a consequence, the physico-chemical properties reported on in this paper provide a significant extension to the range of data available, hereby providing useful data to practical as

  15. Shock-induced chemical reactions in titanium-silicon powder mixtures of different morphologies: Time-resolved pressure measurements and materials analysis

    Science.gov (United States)

    Thadhani, N. N.; Graham, R. A.; Royal, T.; Dunbar, E.; Anderson, M. U.; Holman, G. T.

    1997-08-01

    The response of porous titanium (Ti) and silicon (Si) powder mixtures with small, medium, and coarse particle morphologies is studied under high-pressure shock loading, employing postshock materials analysis as well as nanosecond, time-resolved pressure measurements. The objective of the work was to provide an experimental basis for development of models describing shock-induced solid-state chemistry. The time-resolved measurements of stress pulses obtained with piezoelectric polymer (poly-vinyl-di-flouride) pressure gauges provided extraordinary sensitivity for determination of rate-dependent shock processes. Both techniques showed clear evidence for shock-induced chemical reactions in medium-morphology powders, while fine and coarse powders showed no evidence for reaction. It was observed that the medium-morphology mixtures experience simultaneous plastic deformation of both Ti and Si particles. Fine morphology powders show particle agglomeration, while coarse Si powders undergo extensive fracture and entrapment within the plastically deformed Ti; such processes decrease the propensity for initiation of shock-induced reactions. The change of deformation mode between fracture and plastic deformation in Si powders of different morphologies is a particularly critical observation. Such a behavior reveals the overriding influence of the shock-induced, viscoplastic deformation and fracture response, which controls the mechanochemical nature of shock-induced solid-state chemistry. The present work in conjunction with our prior studies, demonstrates that the initiation of chemical reactions in shock compression of powders is controlled by solid-state mechanochemical processes, and cannot be qualitatively or quantitatively described by thermochemical models.

  16. Mixture Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Piepel, Gregory F.

    2007-12-01

    A mixture experiment involves combining two or more components in various proportions or amounts and then measuring one or more responses for the resulting end products. Other factors that affect the response(s), such as process variables and/or the total amount of the mixture, may also be studied in the experiment. A mixture experiment design specifies the combinations of mixture components and other experimental factors (if any) to be studied and the response variable(s) to be measured. Mixture experiment data analyses are then used to achieve the desired goals, which may include (i) understanding the effects of components and other factors on the response(s), (ii) identifying components and other factors with significant and nonsignificant effects on the response(s), (iii) developing models for predicting the response(s) as functions of the mixture components and any other factors, and (iv) developing end-products with desired values and uncertainties of the response(s). Given a mixture experiment problem, a practitioner must consider the possible approaches for designing the experiment and analyzing the data, and then select the approach best suited to the problem. Eight possible approaches include 1) component proportions, 2) mathematically independent variables, 3) slack variable, 4) mixture amount, 5) component amounts, 6) mixture process variable, 7) mixture of mixtures, and 8) multi-factor mixture. The article provides an overview of the mixture experiment designs, models, and data analyses for these approaches.

  17. Methods used for testing toxicity of industrial chemicals and the need of their international unification.

    Science.gov (United States)

    Vyskocil, A; Tusl, M

    1989-01-01

    The work presented here provides a demonstration of approaches in testing chemical substances in the world, comparison of various guidelines, shows differences in them with the aim to unify them as much as possible and thus to achieve their international comparability. First chapter includes a comparison of American and European approaches to Good Laboratory Practice (GLP). Some parts of American GLP seem to be specific for the USA only and thus they are not suitable for application on the international level where countries having different systems of government and various levels of their economy would have to observe them. GLP published in OECD and ECETOC guidelines seem to be most beneficial for needs of socialist countries. OECD, EEC, EPA/FIFRA, EPA/TSCA, Japan/MAFF and UK/HSC guidelines are compared in subsequent chapters and recommendations given by ECETOC and the authors of this work for unification of the guidelines are presented as well. Some parts of OECD guidelines are specified in detail there especially those which are most suitable for CMEA countries. Differences or supplements contained in CMEA recommendations are presented in the end of each chapter. Acute, subchronic and chronic toxicity tests were compared as well as carcinogenicity, combined carcinogenicity/chronic toxicity studies and reproductive toxicity tests.

  18. Comparison of NIR chemical imaging with conventional NIR, Raman and ATR-IR spectroscopy for quantification of furosemide crystal polymorphs in ternary powder mixtures.

    Science.gov (United States)

    Schönbichler, S A; Bittner, L K H; Weiss, A K H; Griesser, U J; Pallua, J D; Huck, C W

    2013-08-01

    The aim of this study was to evaluate the ability of near-infrared chemical imaging (NIR-CI), near-infrared (NIR), Raman and attenuated-total-reflectance infrared (ATR-IR) spectroscopy to quantify three polymorphic forms (I, II, III) of furosemide in ternary powder mixtures. For this purpose, partial least-squares (PLS) regression models were developed, and different data preprocessing algorithms such as normalization, standard normal variate (SNV), multiplicative scatter correction (MSC) and 1st to 3rd derivatives were applied to reduce the influence of systematic disturbances. The performance of the methods was evaluated by comparison of the standard error of cross-validation (SECV), R(2), and the ratio performance deviation (RPD). Limits of detection (LOD) and limits of quantification (LOQ) of all methods were determined. For NIR-CI, a SECVcorr-spec and a SECVsingle-pixel corrected were calculated to assess the loss of accuracy by taking advantage of the spatial information. NIR-CI showed a SECVcorr-spec (SECVsingle-pixel corrected) of 2.82% (3.71%), 3.49% (4.65%), and 4.10% (5.06%) for form I, II, III. NIR had a SECV of 2.98%, 3.62%, and 2.75%, and Raman reached 3.25%, 3.08%, and 3.18%. The SECV of the ATR-IR models were 7.46%, 7.18%, and 12.08%. This study proves that NIR-CI, NIR, and Raman are well suited to quantify forms I-III of furosemide in ternary mixtures. Because of the pressure-dependent conversion of form II to form I, ATR-IR was found to be less appropriate for an accurate quantification of the mixtures. In this study, the capability of NIR-CI for the quantification of polymorphic ternary mixtures was compared with conventional spectroscopic techniques for the first time. For this purpose, a new way of spectra selection was chosen, and two kinds of SECVs were calculated to achieve a better comparability of NIR-CI to NIR, Raman, and ATR-IR.

  19. On Modeling the Response of Synovial Fluid: Unsteady Flow of a Shear-Thinning, Chemically-Reacting Fluid Mixture

    CERN Document Server

    Bridges, Craig; Rajagopal, K R

    2010-01-01

    We study the flow of a shear-thinning, chemically-reacting fluid that could be used to model the flow of the synovial fluid. The actual geometry where the flow of the synovial fluid takes place is very complicated, and therefore the governing equations are not amenable to simple mathematical analysis. In order to understand the response of the model, we choose to study the flow in a simple geometry. While the flow domain is not a geometry relevant to the flow of the synovial fluid in the human body it yet provides a flow which can be used to assess the efficacy of different models that have been proposed to describe synovial fluids. We study the flow in the annular region between two cylinders, one of which is undergoing unsteady oscillations about their common axis, in order to understand the quintessential behavioral characteristics of the synovial fluid. We use the three models suggested by Hron et al. [ J. Hron, J. M\\'{a}lek, P. Pust\\v{e}jovsk\\'{a}, K. R. Rajagopal, On concentration dependent shear-thinni...

  20. Chemical kinetic study of the oxidation of a biodiesel-bioethanol surrogate fuel: methyl octanoate-ethanol mixtures.

    Science.gov (United States)

    Togbé, C; May-Carle, J-B; Dayma, G; Dagaut, P

    2010-03-25

    There is a growing interest for using bioethanol-biodiesel fuel blends in diesel engines but no kinetic data and model for their combustion were available. Therefore, the kinetics of oxidation of a biodiesel-bioethanol surrogate fuel (methyl octanoate-ethanol) was studied experimentally in a jet-stirred reactor at 10 atm and constant residence time, over the temperature range 560-1160 K, and for several equivalence ratios (0.5-2). Concentration profiles of reactants, stable intermediates, and final products were obtained by probe sampling followed by online FTIR, and off-line gas chromatography analyses. The oxidation of this fuel in these conditions was modeled using a detailed chemical kinetic reaction mechanism consisting of 4592 reversible reactions and 1087 species. The proposed kinetic reaction mechanism yielded a good representation of the kinetics of oxidation of this biodiesel-bioethanol surrogate under the JSR conditions. The modeling was used to delineate the reactions triggering the low-temperature oxidation of ethanol important for diesel engine applications.

  1. [Dissemination of the Japanese version of the International Chemical Safety Card (ICSC) on the World Wide Web (WWW)].

    Science.gov (United States)

    Yamamoto, M; Yokote, N; Morita, M; Nakano, T; Ishikawa, K; Kaminuma, T

    1997-01-01

    ge of the Japanese version of the International Chemical Safety Cards (ICSC). We prepared the Japanese text files of ICSC, converted them into HTML files and also prepared the dictionary database for the retrieval system, using programs which we developed. These programs shortened the time of work remarkably. 2D- and 3D-structures of chemicals were also incorporated in each ICSC page. Approximately 900 ICSCs in Japanese are provided at the moment on the homepage.

  2. 76 FR 68809 - Bureau of International Security and Nonproliferation; Termination of Chemical and Biological...

    Science.gov (United States)

    2011-11-07

    ... Nonproliferation; Termination of Chemical and Biological Weapons (CBW) Proliferation Sanctions Against a Foreign... CONTACT: Pamela K. Durham, Office of Missile, Biological, and Chemical Nonproliferation, Bureau of... government, project, or entity in its efforts to acquire chemical or biological weapons capability:...

  3. Solubilidade de micronutrientes contidos em formulações de fertilizantes, em extratores químicos Micronutrient solubility in fertilizer mixtures by chemical extractors

    Directory of Open Access Journals (Sweden)

    J. C. Alcarde

    2003-04-01

    Full Text Available A legislação brasileira adota o teor total para a garantia dos micronutrientes em fertilizantes. Isso permite a utilização de subprodutos de várias origens, baratos, mas que nem sempre apresentam os micronutrientes em formas disponíveis às plantas. Estudou-se a solubilidade dos micronutrientes em formulações de fertilizantes, utilizando os extratores água e soluções de ácido cítrico 20 g L-1 e citrato neutro de amônio (1 + 9, já usados na avaliação de matérias-primas. Os resultados foram semelhantes, tanto na avaliação das formulações como de matérias-primas, isto é, a solução de ácido cítrico a 20 g L-1 possibilita avaliar, com mais segurança, o conteúdo de micronutrientes em formulações de fertilizantes, representando uma alternativa para o teor total, que não é um critério adequado, do ponto de vista agronômico, para avaliar os micronutrientes contidos em fertilizantes.In Brazilian legislation, the control for micronutrient concentrations in mineral fertilizers considers the total content. As a consequence, low-cost by-products and even industrial residues are generally used as a source for micronutrients, despite their low availability to plants. To evaluate fertilizer solubilities, water, citric acid 20 g L-1, and neutral ammonium citrate (1 + 9 extracting solutions were applied to mixtures containing micronutrients. The same study was realized for micronutrient sources. Results were similar for both sources and mixtures. Citric acid solution 20 g L-1 was the most promising option to evaluate micronutrient contents in fertilizer mixtures. From the agronomic point of view, the total content is an inadequate criterion for the determination of micronutrient contents in chemical fertilizers.

  4. Using biological and physico-chemical test methods to assess the role of concrete mixture design in resistance to microbially induced corrosion

    Science.gov (United States)

    House, Mitchell Wayne

    Concrete is the most widely used material for construction of wastewater collection, storage, and treatment infrastructure. The chemical and physical characteristics of hydrated portland cement make it susceptible to degradation under highly acidic conditions. As a result, some concrete wastewater infrastructure may be susceptible to a multi-stage degradation process known as microbially induced corrosion, or MIC. MIC begins with the production of aqueous hydrogen sulfide (H2S(aq)) by anaerobic sulfate reducing bacteria present below the waterline. H2S(aq) partitions to the gas phase where it is oxidized to sulfuric acid by the aerobic sulfur oxidizing bacteria Thiobacillus that resides on concrete surfaces above the waterline. Sulfuric acid then attacks the cement paste portion of the concrete matrix through decalcification of calcium hydroxide and calcium silica hydrate coupled with the formation of expansive corrosion products. The attack proceeds inward resulting in reduced service life and potential failure of the concrete structure. There are several challenges associated with assessing a concrete's susceptibility to MIC. First, no standard laboratory tests exist to assess concrete resistance to MIC. Straightforward reproduction of MIC in the laboratory is complicated by the use of microorganisms and hydrogen sulfide gas. Physico-chemical tests simulating MIC by immersing concrete specimens in sulfuric acid offer a convenient alternative, but do not accurately capture the damage mechanisms associated with biological corrosion. Comparison of results between research studies is difficult due to discrepancies that can arise in experimental methods even if current ASTM standards are followed. This thesis presents two experimental methods to evaluate concrete resistance to MIC: one biological and one physico-chemical. Efforts are made to address the critical aspects of each testing method currently absent in the literature. The first method presented is a new test

  5. The JaCVAM international validation study on the in vivo comet assay: Selection of test chemicals.

    Science.gov (United States)

    Morita, Takeshi; Uno, Yoshifumi; Honma, Masamitsu; Kojima, Hajime; Hayashi, Makoto; Tice, Raymond R; Corvi, Raffaella; Schechtman, Leonard

    2015-07-01

    The Japanese Center for the Validation of Alternative Methods (JaCVAM) sponsored an international prevalidation and validation study of the in vivo rat alkaline pH comet assay. The main objective of the study was to assess the sensitivity and specificity of the assay for correctly identifying genotoxic carcinogens, as compared with the traditional rat liver unscheduled DNA synthesis assay. Based on existing carcinogenicity and genotoxicity data and chemical class information, 90 chemicals were identified as primary candidates for use in the validation study. From these 90 chemicals, 46 secondary candidates and then 40 final chemicals were selected based on a sufficiency of carcinogenic and genotoxic data, differences in chemical class or genotoxic or carcinogenic mode of action (MOA), availability, price, and ease of handling. These 40 chemicals included 19 genotoxic carcinogens, 6 genotoxic non-carcinogens, 7 non-genotoxic carcinogens and 8 non-genotoxic non-carcinogens. "Genotoxicity" was defined as positive in the Ames mutagenicity test or in one of the standard in vivo genotoxicity tests (primarily the erythrocyte micronucleus assay). These chemicals covered various chemicals classes, MOAs, and genotoxicity profiles and were considered to be suitable for the purpose of the validation study. General principles of chemical selection for validation studies are discussed.

  6. Adsorption of Dimethyldodecylamine Oxide and Its Mixtures with Triton X-100 at the Hydrophilic Silica/Water Interface Studied Using Total Internal Reflection Raman Spectroscopy.

    Science.gov (United States)

    Ngo, Dien; Baldelli, Steven

    2016-12-08

    Adsorption of dimethyldodecylamine oxide (DDAO) and its mixtures with Triton X-100 (TX-100) at the hydrophilic silica/water interface has been studied using total internal reflection (TIR) Raman spectroscopy and target factor analysis (TFA). The use of a linear vibrational spectroscopic technique helps obtain information on molecular behavior, adsorbed amount, and conformational order of surfactant molecules at the interface. The results obtained from polarized Raman measurements of pure DDAO show insignificant changes in the orientation and conformational order of surface molecules as a function of DDAO bulk concentrations. The adsorption isotherm of pure DDAO shows a change in the structure of the adsorbed layer at concentrations close to the critical micelle concentration (cmc). TFA reveals that, for a low concentration of DDAO (0.30 mM in this study), adsorption of both DDAO and TX-100 in the mixed surfactants was enhanced at low TX-100 concentrations. The synergistic effect is dominant at low concentrations of TX-100, with enhanced adsorption of both surfactants. Although competitive adsorption is effective at high concentrations of TX-100, the presence of a small amount of DDAO at the interface still enhances TX-100 adsorption. When DDAO concentrations are increased to 1.00 mM, TX-100 replaces DDAO molecules on the surface when TX-100 concentration is increased.

  7. Atmospheric pressure laser-induced acoustic desorption chemical ionization Fourier transform ion cyclotron resonance mass spectrometry for the analysis of complex mixtures.

    Science.gov (United States)

    Nyadong, Leonard; McKenna, Amy M; Hendrickson, Christopher L; Rodgers, Ryan P; Marshall, Alan G

    2011-03-01

    We present a novel nonresonant laser-based matrix-free atmospheric pressure ionization technique, atmospheric pressure laser-induced acoustic desorption chemical ionization (AP/LIAD-CI). The technique decouples analyte desorption from subsequent ionization by reagent ions generated from a corona discharge initiated in ambient air or in the presence of vaporized toluene as a CI dopant at room temperature. Analyte desorption is initiated by a shock wave induced in a titanium foil coated with electrosprayed sample, irradiated from the rear side by high-energy laser pulses. The technique enables facile and independent optimization of the analyte desorption, ionization, and sampling events, for coupling to any mass analyzer with an AP interface. Moreover, the generated analyte ions are efficiently thermalized by collisions with atmospheric gases, thereby reducing fragmentation. We have coupled AP/LIAD-CI to ultrahigh-resolution FT-ICR MS to generate predominantly [M + H](+) or M(+•) ions to resolve and identify thousands of elemental compositions from organic mixtures as complex as petroleum crude oil distillates. Finally, we have optimized the AP/LIAD CI process and investigated ionization mechanisms by systematic variation of placement of the sample, placement of the corona discharge needle, discharge current, gas flow rate, and inclusion of toluene as a dopant.

  8. Thermal Modification of a-SiC:H Films Deposited by Plasma Enhanced Chemical Vapour Deposition from CH4+SiH4 Mixtures

    Institute of Scientific and Technical Information of China (English)

    刘玉学; 王宁会; 刘益春; 申德振; 范希武; 李灵燮

    2001-01-01

    The effects of thermal annealing on photoluminescence (PL) and structural properties of a-Si1-xCx :H films deposited by plasma enhanced chemical vapour deposition from CH4+SiH4 mixtures are studied by using infrared, PL and transmittance-reflectance spectra. In a-SiC:H network, high-temperature annealing gives rise to the effusion of hydrogen from strongly bonded hydrogen in SiH, SiH2, (SiH2)n, SiCHn and CHn configurations and the break of weak C-C, Si-Si and C-Si bonds. A structural rearrangement will occur, which causes a significant correlation of the position and intensity of the PL signal with the annealing temperature. The redshift of the PL peak is related to the destruction of the confining power of barriers. However, the PL intensity does not have a significant correlation with the annealing temperature for a C-rich a-SiC:H network, which refers to the formation of π-bond cluster as increasing carbon content. It is indicated that the thermal stability of C-rich a-Si1-xCx:H films is better than that of Si-like a-Si1-xCx :H films.

  9. A Methodological Approach to Assessing the Health Impact of Environmental Chemical Mixtures: PCBs and Hypertension in the National Health and Nutrition Examination Survey

    Directory of Open Access Journals (Sweden)

    Paul White

    2011-11-01

    Full Text Available We describe an approach to examine the association between exposure to chemical mixtures and a health outcome, using as our case study polychlorinated biphenyls (PCBs and hypertension. The association between serum PCB and hypertension among participants in the 1999–2004 National Health and Nutrition Examination Survey was examined. First, unconditional multivariate logistic regression was used to estimate odds ratios and associated 95% confidence intervals. Next, correlation and multicollinearity among PCB congeners was evaluated, and clustering analyses performed to determine groups of related congeners. Finally, a weighted sum was constructed to represent the relative importance of each congener in relation to hypertension risk. PCB serum concentrations varied by demographic characteristics, and were on average higher among those with hypertension. Logistic regression results showed mixed findings by congener and class. Further analyses identified groupings of correlated PCBs. Using a weighted sum approach to equalize different ranges and potencies, PCBs 66, 101, 118, 128 and 187 were significantly associated with increased risk of hypertension. Epidemiologic data were used to demonstrate an approach to evaluating the association between a complex environmental exposure and health outcome. The complexity of analyzing a large number of related exposures, where each may have different potency and range, are addressed in the context of the association between hypertension risk and exposure to PCBs.

  10. A methodological approach to assessing the health impact of environmental chemical mixtures: PCBs and hypertension in the National Health and Nutrition Examination Survey.

    Science.gov (United States)

    Yorita Christensen, Krista L; White, Paul

    2011-11-01

    We describe an approach to examine the association between exposure to chemical mixtures and a health outcome, using as our case study polychlorinated biphenyls (PCBs) and hypertension. The association between serum PCB and hypertension among participants in the 1999-2004 National Health and Nutrition Examination Survey was examined. First, unconditional multivariate logistic regression was used to estimate odds ratios and associated 95% confidence intervals. Next, correlation and multicollinearity among PCB congeners was evaluated, and clustering analyses performed to determine groups of related congeners. Finally, a weighted sum was constructed to represent the relative importance of each congener in relation to hypertension risk. PCB serum concentrations varied by demographic characteristics, and were on average higher among those with hypertension. Logistic regression results showed mixed findings by congener and class. Further analyses identified groupings of correlated PCBs. Using a weighted sum approach to equalize different ranges and potencies, PCBs 66, 101, 118, 128 and 187 were significantly associated with increased risk of hypertension. Epidemiologic data were used to demonstrate an approach to evaluating the association between a complex environmental exposure and health outcome. The complexity of analyzing a large number of related exposures, where each may have different potency and range, are addressed in the context of the association between hypertension risk and exposure to PCBs.

  11. International Research Project on the Effects of Chemical Ageing of Polymers on Performance Properties: Chemical and Thermal Analysis

    Science.gov (United States)

    Bulluck, J. W.; Rushing, R. A.

    1996-01-01

    Work during the past six months has included significant research in several areas aimed at further clarification of the aging and chemical failure mechanism of thermoplastics (PVDF or Tefzel) pipes. Among the areas investigated were the crystallinity changes associated with both the Coflon and Tefzel after various simulated environmental exposures using X-ray diffraction analysis. We have found that significant changes in polymer crystallinity levels occur as a function of the exposures. These crystallinity changes may have important consequences on the fracture, fatigue, tensile, and chemical resistance of the materials. We have also noted small changes in the molecular weight distribution. Again these changes may result in variations in the mechanical and chemical properties in the material. We conducted numerous analytical studies with methods including X-ray Diffraction, Gel Permeation Chromatography, Fourier Transform Infrared Spectroscopy, Ultra- Violet Scanning Analysis, GC/Mass Spectrometry, Differential Scanning Calorimetry and Thermomechanical Analysis. In the ultra-violet analysis we noted the presence of an absorption band indicative of triene formation. We investigated a number of aged samples of both Tefzel and Coflon that were forwarded from MERL. We also cast films at SWT and subjected these films to a refluxing methanol 1% ethylene diamine solution. An updated literature search was conducted using Dialog and DROLLS to identify any new papers that may have been published in the open literature since the start of this project. The updated literature search and abstracts are contained in the Appendix section of this report.

  12. Chemical and Physical Characteristics of Cocopeat-Based Media Mixtures and Their Effects on the Growth and Development of Celosia cristata

    Directory of Open Access Journals (Sweden)

    Yahya Awang

    2009-01-01

    Full Text Available Problem statement: Cocopeat is considered as a good growing media component with acceptable pH, electrical conductivity and other chemical attributes but it has been recognized to have high water holding capacity which causes poor air-water relationship, leading to low aeration within the medium, thus affecting the oxygen diffusion to the roots. Incorporation of coarser materials into cocopeat could improve the aeration status of the media. Approach: Selected chemical and physical characteristics of five types of growing media comprising of (v/v 100% cocopeat, 70% cocopeat: 30% burnt rice hull, 70% cocopeat: 30% perlite, 70% cocopeat: 30% kenaf core fiber and 40% cocopeat: 60% kenaf core fiber were determined and their suitability as growing media was tested using Celosia cristata. Data on pH, Electrical Conductivity (EC and various aspects of air-water relationships of the media, as well on growth and flowering of test plant and leaf nutrient contents were collected. Results: Initial pH for 100% cocopeat and 70% cocopeat: 30% kenaf core fiber was higher than the other media but the values were eventually similar by the end of the study. The bulk density and EC of media containing burnt rice hull was markedly higher than the other media (0.12 g cm3 and 0.48 mS cm-1, respectively. Media comprising of 70% cocopeat: 30% burnt rice hull and 70% cocopeat: 30% perlite contained higher air content. The former held the highest volume of available water. Incorporation of burnt rice hull and perlite into cocopeat increased water absorption ability of the media which reached saturation earlier than the other media. Addition of burnt rice hull (30%, perlite (30% and kenaf core fiber (30% to cocopeat elevated the Air-Filled Porosity (AFP of the media. The growth and flowering of Celosia cristata were the greatest when grown in a mixture of 70% cocopeat: 30% burnt rice hull and perhaps linked with a good balance

  13. Perception of trigeminal mixtures.

    Science.gov (United States)

    Filiou, Renée-Pier; Lepore, Franco; Bryant, Bruce; Lundström, Johan N; Frasnelli, Johannes

    2015-01-01

    The trigeminal system is a chemical sense allowing for the perception of chemosensory information in our environment. However, contrary to smell and taste, we lack a thorough understanding of the trigeminal processing of mixtures. We, therefore, investigated trigeminal perception using mixtures of 3 relatively receptor-specific agonists together with one control odor in different proportions to determine basic perceptual dimensions of trigeminal perception. We found that 4 main dimensions were linked to trigeminal perception: sensations of intensity, warmth, coldness, and pain. We subsequently investigated perception of binary mixtures of trigeminal stimuli by means of these 4 perceptual dimensions using different concentrations of a cooling stimulus (eucalyptol) mixed with a stimulus that evokes warmth perception (cinnamaldehyde). To determine if sensory interactions are mainly of central or peripheral origin, we presented stimuli in a physical "mixture" or as a "combination" presented separately to individual nostrils. Results showed that mixtures generally yielded higher ratings than combinations on the trigeminal dimensions "intensity," "warm," and "painful," whereas combinations yielded higher ratings than mixtures on the trigeminal dimension "cold." These results suggest dimension-specific interactions in the perception of trigeminal mixtures, which may be explained by particular interactions that may take place on peripheral or central levels.

  14. The selective conversion of glutamic acid in amino acid mixtures using glutamate decarboxylase--a means of separating amino acids for synthesizing biobased chemicals.

    Science.gov (United States)

    Teng, Yinglai; Scott, Elinor L; Sanders, Johan P M

    2014-01-01

    Amino acids (AAs) derived from hydrolysis of protein rest streams are interesting feedstocks for the chemical industry due to their functionality. However, separation of AAs is required before they can be used for further applications. Electrodialysis may be applied to separate AAs, but its efficiency is limited when separating AAs with similar isoelectric points. To aid the separation, specific conversion of an AA to a useful product with different charge behavior to the remaining compounds is desired. Here the separation of L-aspartic acid (Asp) and L-glutamic acid (Glu) was studied. L-Glutamate α-decarboxylase (GAD, Type I, EC 4.1.1.15) was applied to specifically convert Glu into γ-aminobutyric acid (GABA). GABA has a different charge behavior from Asp therefore allowing a potential separation by electrodialysis. Competitive inhibition and reduced operational stability caused by Asp could be eliminated by maintaining a sufficiently high concentration of Glu. Immobilization of GAD does not reduce the enzyme's initial activity. However, the operational stability was slightly reduced. An initial study on the reaction operating in a continuous mode was performed using a column reactor packed with immobilized GAD. As the reaction mixture was only passed once through the reactor, the conversion of Glu was lower than expected. To complete the conversion of Glu, the stream containing Asp and unreacted Glu might be recirculated back to the reactor after GABA has been removed. Overall, the reaction by GAD is specific to Glu and can be applied to aid the electrodialysis separation of Asp and Glu.

  15. Proceedings of the 3. International conference on waste management in the chemical and petrochemical industries. Volume 1 and 2.

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Francisco F.; Pereira Filho, Francisco A.; Almeida, Sergio A.S. [eds.

    1993-12-31

    To produce without pollution is today a mandate for the preservation of our society. To produce cleaner means to conserve energy and natural resources, to reduce the use of toxic substances, to invest in the evolution of products and production processes towards a minimum of residues. The Third International Conference on Waste Minimization in the Chemical and Petrochemical Industries addresses these challenging questions regarding waste minimization

  16. A Demonstration of the Uncertainty in Predicting the Estrogenic Activity of Individual Chemicals and Mixtures From an In Vitro Estrogen Receptor Transcriptional Activation Assay (T47D-KBluc) to the In Vivo Uterotrophic Assay Using Oral Exposure.

    Science.gov (United States)

    Conley, Justin M; Hannas, Bethany R; Furr, Johnathan R; Wilson, Vickie S; Gray, L Earl

    2016-10-01

    In vitro estrogen receptor assays are valuable tools for identifying environmental samples and chemicals that display estrogenic activity. However, in vitro potency cannot necessarily be extrapolated to estimates of in vivo potency because in vitro assays are currently unable to fully account for absorption, distribution, metabolism, and excretion. To explore this issue, we calculated relative potency factors (RPF), using 17α-ethinyl estradiol (EE2) as the reference compound, for several chemicals and mixtures in the T47D-KBluc estrogen receptor transactivation assay. In vitro RPFs were used to predict rat oral uterotrophic assay responses for these chemicals and mixtures. EE2, 17β-estradiol (E2), benzyl-butyl phthalate (BBP), bisphenol-A (BPA), bisphenol-AF (BPAF), bisphenol-C (BPC), bisphenol-S (BPS), and methoxychlor (MET) were tested individually, while BPS + MET, BPAF + MET, and BPAF + BPC + BPS + EE2 + MET were tested as equipotent mixtures. In vivo ED50 values for BPA, BPAF, and BPC were accurately predicted using in vitro data; however, E2 was less potent than predicted, BBP was a false positive, and BPS and MET were 76.6 and 368.3-fold more active in vivo than predicted from the in vitro potency, respectively. Further, mixture ED50 values were more accurately predicted by the dose addition model using individual chemical in vivo uterotrophic data (0.7-1.5-fold difference from observed) than in vitro data (1.4-86.8-fold). Overall, these data illustrate the potential for both underestimating and overestimating in vivo potency from predictions made with in vitro data for compounds that undergo substantial disposition following oral administration. Accounting for aspects of toxicokinetics, notably metabolism, in in vitro models will be necessary for accurate in vitro-to-in vivo extrapolations.

  17. EVALUATION REPORT SCIENCE APPLICATIONS INTERNATIONAL CORPORATION S-CAD CHEMICAL AGENT DETECTION SYSTEM

    Science.gov (United States)

    The USEPA's National Homeland Security Research Center (NHSRC)Technology Testing and Evaluation Program (TTEP) is carrying out performance tests on homeland security technologies. Under TTEP, Battelle recently evaluated the performance of the Science Applications International Co...

  18. Numerical investigation of biogas diffusion flames characteristics under several operation conditions in counter-flow configuration with an emphasis on thermal and chemical effects of CO2 in the fuel mixture

    Science.gov (United States)

    Mameri, A.; Tabet, F.; Hadef, A.

    2017-03-01

    This study addresses the influence of several operating conditions (composition and ambient pressure) on biogas diffusion flame structure and NO emissions with particular attention on thermal and chemical effect of CO2. The biogas flame is modeled by a counter flow diffusion flame and analyzed in mixture fraction space using flamelet approach. The GRI Mech-3.0 mechanism that involves 53 species and 325 reactions is adopted for the oxidation chemistry. It has been observed that flame properties are very sensitive to biogas composition and pressure. CO2 addition decreases flame temperature by both thermal and chemical effects. Added CO2 may participate in chemical reaction due to thermal dissociation (chemical effect). Excessively supplied CO2 plays the role of pure diluent (thermal effect). The ambient pressure rise increases temperature and reduces flame thickness, radiation losses and dissociation amount. At high pressure, recombination reactions coupled with chain carrier radicals reduction, diminishes NO mass fraction.

  19. Laboratory measurements of selected optical, physical, chemical, and remote-sensing properties of five water mixtures containing Calvert clay and a nonfluorescing dye

    Science.gov (United States)

    Usry, J. W.; Whitlock, C. H.; Poole, L. R.; Witte, W. G., Jr.

    1981-01-01

    Total suspended solids concentrations ranged from 6.1 ppm to 24.3 ppm and sizes ranged between 1.5 micrometers and 10 micrometers with the most frequently occurring size less than 2 micrometers. Iron concentration was less than 1 percent of the total suspended solids. Nonfluorescing dye concentrations of the two mixtures were 20 ppm and 40 ppm. Attenuation coefficient for the five mixtures ranged from 4.8/m to 21.3/m. Variations in volume scattering function with phase angle were typical. Variations in attenuation and absorption coefficient with wavelength were similar for the mixtures without the dye. Attenuation coefficient of the mixtures with the dye increased for wavelengths less than 600 nm due to the dye's strong absorption peak near 500 nm. Reflectance increased as the concentration of Calvert clay increased and peaked near 600 nm. The nonfluorescent dye decreased the magnitude of the peak, but had practically no effect on the variation for wavelengths greater than 640 nm. At wavelengths less than 600 nm, the spectral variations of the mixtures with the dye were significantly different from those mixtures without the dye.

  20. The properties of the mixture of beef tallow and rapeseed oil with a high content of tallow after chemical and enzymatic interesterification

    Directory of Open Access Journals (Sweden)

    Gruczynska, Eliza

    2005-12-01

    Full Text Available A mixture of beef tallow with rapeseed oil (3:1 wt/wt was interesterified using sodium metoxide or immobilized lipases from Rhizomucor miehei (Lipozyme IM and Candida antarctica (Novozym 435 as catalysts. Chemical interesterifications were carried out at 60 and 90 ºC for 0.5 and 1.5 h using 0.4, 0.6 and 1.0 wt-% CH3ONa. Depending on the catalyst used enzymatic interesterifications were carried out at 60 ºC for 8 h (Lipozyme IM or at 80 ºC for 4 h (Novozym 435. The catalysts doses were kept constant (8 % but the water content in catalysts varied from 2 to 10 %. The starting mixture and the interesterified products were separated by column chromatography into a pure triacylglycerol fraction and a non-triacylglycerol fraction, which contained free fatty acids, mono- and diacylglycerols. It was found that the concentrations of free fatty acids and partial acylglycerols increased after interesterification. The slip melting points and solid fat contents of the triacylglycerol fractions isolated from interesterified fats were lower when compared with nonesterified blends. The sn-2 and sn-1,3 distributions of fatty acids in the triacylglycerol fractions before and after interesterification were determined.These distributions were random after chemical interesterification and near random when Novozym 435 was used. When Lipozyme IM was used, the fatty acid composition at the sn-2 position remained practically unchanged compared with the starting blend. The interesterified fats and isolated triacylglycerols had reduced oxidative stability, as assessed by Rancimat induction times. The addition of 0.02 % of BHA or BHT to the interesterified fats improved their stabilitie.Una mezcla de sebo con aceite de colza (3:1 p/p fue interesterificada usando metóxido de sodio y lipasas inmovilizadas de Rhizomucor miehei (Lipozyme IM and Candida antarctica (Novozym 435 como catalizadores. La interesterificación química se llevó a cabo a 60 ºC y 90

  1. Ultrasonic Investigations of Molecular Interaction in Binary Mixtures of Benzyl Benzoate with Acetonitrile and Benzonitrile

    Directory of Open Access Journals (Sweden)

    N. Jaya Madhuri

    2011-01-01

    Full Text Available Ultrasonic velocity, density and viscosity have been measured in the binary mixtures of benzyl benzoate with acetonitrile, benzonitrile at three temperatures 30, 40 and 50 °C. From the experimental data, thermodynamic parameters like adiabatic compressibility, internal pressure, enthalpy, activation energy etc., were computed and the molecular interactions were predicted based on the variation of excess parameters in the mixture. Also theoretical evaluation of velocities was made employing the standard theories. CFT and NOMOTO were found to have an edge. All the three mixtures have shown out strong intermolecular interactions between the unlike molecules and endothermic type of chemical reaction.

  2. Evidence from pharmacology and pathophysiology suggests that chemicals with dissimilar mechanisms of action could be of bigger concern in the toxicological risk assessment of chemical mixtures than chemicals with a similar mechanism of action

    DEFF Research Database (Denmark)

    Hadrup, Niels

    2014-01-01

    mechanisms of action, similar modes of action or with common target organs. In the European Union, efforts are currently being made to subgroup chemicals according to this need. However, it remains to be determined whether this is the best strategy to obtain data for risk assessment. In conditions...... such as cancer or HIV, it is generally recognised that pharmacological combination therapy targeting different mechanisms of action is more effective than a strategy where only one mechanism is targeted. Moreover, in diseases such as acute myocardial infarction and congestive heart failure, several organ systems...

  3. CHEMICALS

    CERN Multimedia

    Medical Service

    2002-01-01

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

  4. Morphoanatomical characterization and chemical study of the internal portion of the stem bark of Sambucus australis Cham. & Schltdl

    Directory of Open Access Journals (Sweden)

    G.C. ALERICO

    2016-01-01

    Full Text Available ABSTRACT The internal part of the stem bark of this species is used to produce a homemade ointment in some regions of the state of Rio Grande do Sul. The purpose of this study is to characterize the morphoanatomy and identify the compounds present in the internal part of the stem bark of S. australis through chemical and histochemical methods. In addition, the best extraction conditions for the sample were determined. It was possible to quantify the rutin and total phenolic compounds, as well as define the Soxhlet method with an 80% hydroethanolic solution as the best method for extracting these compounds from the bark of the species. The portion of the stem bark that is popularly used could also be determined. Based on the results, new studies will be performed in order to identify other characteristics of the species and the possible reasons that sustain its traditional use.

  5. Towards consistent and reliable Dutch and international energy statistics for the chemical industry

    NARCIS (Netherlands)

    Neelis, M.L.; Pouwelse, J.W.

    2008-01-01

    Consistent and reliable energy statistics are of vital importance for proper monitoring of energy-efficiency policies. In recent studies, irregularities have been reported in the Dutch energy statistics for the chemical industry. We studied in depth the company data that form the basis of the energy

  6. Internal rotation potential and structure of six fluorine substituted nitrobenzenes studied by microwave spectroscopy supported by quantum chemical calculations

    DEFF Research Database (Denmark)

    Larsen, Niels Wessel; Nielsen, Ole Vesterlund

    2014-01-01

    Microwave spectra of the vibrational ground state and several torsionally excited states were used to investigate the internal rotation potential and the structure of six fluorine substituted nitrobenzenes: 3-fluoro- and 4-fluoronitrobenzene were planar molecules just as nitrobenzene whereas 2....... For the planar molecules and for 2,4,6-trifluoronitrobenzene V 2 and V4 were determined using assumptions about V 6 based on the quantum chemical calculations. For all non-planar molecules tunnelling through the lower of the two barriers was observed as a splitting of the torsional energy levels. © 2014 Elsevier...

  7. Inspection relief for BWR internal components with noble metal chemical application (NMCA)

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, J.A. [Exelom Corp., Clinton Power Station, Clinton, IL (United States); Pathania, R.S. [EPRI, Palo Alto, CA (United States)

    2001-07-01

    The BWRVIP has developed methods to verify effectiveness of NMCA for mitigation of intergranular stress corrosion cracking (IGSCC). One of the major problems in demonstrating the effectiveness of NMCA inside the reactor vessel is the difficulty of measuring the electrochemical driving force of IGSCC of the various reactor internal components. Many plants do not have direct ECP measurements available at pertinent locations such as the lower plenum. Even those plants that do have direct measurements available recognize that such local measurements may not be representative of all potentially susceptible component surfaces. Therefore, it is desirable to develop valid supplementary techniques that do not depend exclusively on direct measurements of the ECP at specific locations to reliably demonstrate NMCA effectiveness. This paper describes the verification methods developed by the BWRVIP and reports on an industry survey which shows how extensively these recommendations are being implemented. Furthermore, the effectiveness of NMCA is dependent upon the uniform application and the durability of the catalytic surface. Results are provided from the durability monitor at the Duane Arnold Energy Center (DAEC) NMCA demonstration project. Based on the crack growth modeling and radiolysis results, a vessel internals inspection program can be developed based on Factors of Improvement (FOIs) for plants that have implemented NMCA. The FOI calculated for each internal component based on crack growth modeling results can be applied to revise the internals inspection interval established in the various BWRVIP inspection and evaluation (I and E) documents. For an example, this paper discusses revisions to the inspection intervals for recirculation piping welds. (author)

  8. Analysis of physical-chemical processes governing SSME internal fluid flows

    Science.gov (United States)

    Singhal, A. K.; Owens, S. F.; Mukerjee, T.; Prakash, C.; Przekwas, A. J.; Kannapel, M.

    1985-01-01

    The basic issues concerning the physical chemical processes of the Space Shuttle Main Engine are discussed. The objectives being to supply the general purpose CFD code PHOENICS and the associated interactive graphics package - GRAFFIC; to demonstrate code usage on SSME related problems; to perform computations and analyses of problems relevant to current and future SSME's; and to participate in the development of new physical models of various processes present in SSME components. These objectives are discussed in detail.

  9. Benzylammonium Thermometer Ions: Internal Energies of Ions Formed by Low Temperature Plasma and Atmospheric Pressure Chemical Ionization.

    Science.gov (United States)

    Stephens, Edward R; Dumlao, Morphy; Xiao, Dan; Zhang, Daming; Donald, William A

    2015-12-01

    The extent of internal energy deposition upon ion formation by low temperature plasma and atmospheric pressure chemical ionization was investigated using novel benzylammonium thermometer ions. C-N heterolytic bond dissociation enthalpies of nine 4-substituted benzylammoniums were calculated using CAM-B3LYP/6-311++G(d,p), which was significantly more accurate than B3LYP/6-311++G(d,p), MP2/6-311++G(d,p), and CBS-QB3 for calculating the enthalpies of 20 heterolytic dissociation reactions that were used to benchmark theory. All 4-substituted benzylammonium thermometer ions fragmented by a single pathway with comparable dissociation entropies, except 4-nitrobenzylammonium. Overall, the extent of energy deposition into ions formed by low temperature plasma was significantly lower than those formed by atmospheric pressure chemical ionization under these conditions. Because benzylamines are volatile, this new suite of thermometer ions should be useful for investigating the extent of internal energy deposition during ion formation for a wide range of ionization methods, including plasma, spray and laser desorption-based techniques. Graphical Abstract ᅟ.

  10. A New Solar Chemical Reactor with an Internally Circulating Fluidized bed for Direct Irradiation of Reacting Particles

    Energy Technology Data Exchange (ETDEWEB)

    Kodama, T.; Enomoto, S.; Hatamachi, T.; Gokon, N.

    2006-07-01

    Solar thermochemical processes require the development of a high temperature solar reactor operating at 1000-1500 degree celsius, such as solar gasification of coal and the thermal reduction of metal oxides as part of a two-step water splitting cycle. Direct solar energy absorption by reacting particles of coal or metal oxides provides efficient heat transfer directly to the reaction site. The present paper describes a new type of the windowed solar chemical reactor directly illuminating reacting particles in an internally circulating fluidized bed. The reactor body is made of stainless steel having a quartz window on the top as aperture. A draft tube is centrally inserted in the fluidized bed region. Gases such as steam, CO2, or N2 are introduced into the draft tube and annulus regions in the bed separately. The concentrated solar radiation passes downwards TROUGH the window and directly heats the internally circulating fluidized bed of reacting particles. The prototype reactor was constructed in a laboratory scale and demonstrated on CO2 gasification of coal coke using solar-simulated, concentrated visible light from sun-simulator as the energy source. About 12% of the maximum chemical storage efficiency was obtained by the solar-simulated gasification of the coke. This new reactor will be also applied for a two-step water splitting cycle using redox metal-oxide particles. (Author)

  11. Internalization of bacterial pathogens in tomatoes and their control by selected chemicals.

    Science.gov (United States)

    Ibarra-Sánchez, L S; Alvarado-Casillas, S; Rodríguez-García, M O; Martínez-Gonzáles, N E; Castillo, A

    2004-07-01

    The effect of different washing or sanitizing agents was compared for preventing or reducing surface and internal contamination of tomatoes by Salmonella Typhimurium and Escherichia coli O157:H7. The tomatoes were inoculated by dipping them in a bacterial suspension containing approximately 6.0 log CFU/ml of each pathogen and then rinsing them with tap water, hypochlorite solution (250 mg/liter), or lactic acid solution (2%, wt/vol). All treatments were applied by dipping or spraying, and solutions were applied at 5, 25, 35, and 55 degrees C. With the exception of the lactic acid dip at 5 degrees C, all treatments reduced both pathogens on the surfaces of the tomatoes by at least 2.9 cycles. No significantly different results were obtained (P > 0.05) with the dipping and spraying techniques. For internalized pathogens, the mean counts for tomatoes treated with water alone or with chlorine ranged from 0.8 to 2.1 log CFU/g. In contrast, after lactic acid spray treatment, all core samples of tomatoes tested negative for Salmonella Typhimurium and, except for one sample with a low but detectable count, all samples tested negative for E. coli O157:H7 with a plate count method. When the absence of pathogens was verified by an enrichment method, Salmonella was not recovered from any samples, whereas two of four samples tested positive for E. coli O157:H7 even though the counts were negative. Few cells of internalized pathogens were able to survive in the center of the tomato during storage at room temperature (25 to 28 degrees C). The average superficial pH of tomatoes treated with tap water, chlorine, or lactic acid was 4.9 to 5.2, 4.1 to 4.3, and 2.5, respectively (P tomatoes treated with different sanitizers. The general practice in the tomato industry is to wash the tomatoes in chlorinated water. However, chlorine is rapidly degraded by organic matter usually present in produce. Therefore, lactic acid sprays may be a more effective alternative for decontaminating

  12. International consensus model for comparative assessment of chemical emissions in LCA

    DEFF Research Database (Denmark)

    Hauschild, Michael Zwicky; Bachmann, Till M.; Huijbregts, Mark A.J.;

    2008-01-01

    but as complex as needed) and transparent consensus model, USEtox, was created producing characterisation factors that fall within the range of factors from the harmonised existing characterisation models. The USEtox model together with factors for several thousand substances are currently under review to form......Under the UNEP-SETAC Life Cycle Initiative the six most commonly used characterisation models for toxic impacts from chemicals were compared and harmonised through a sequence of workshops removing differences which were unintentional or unnecessary. A parsimonious (as simple as possible...

  13. Human exposure to unconventional natural gas development: A public health demonstration of periodic high exposure to chemical mixtures in ambient air.

    Science.gov (United States)

    Brown, David R; Lewis, Celia; Weinberger, Beth I

    2015-01-01

    Directional drilling and hydraulic fracturing of shale gas and oil bring industrial activity into close proximity to residences, schools, daycare centers and places where people spend their time. Multiple gas production sources can be sited near residences. Health care providers evaluating patient health need to know the chemicals present, the emissions from different sites and the intensity and frequency of the exposures. This research describes a hypothetical case study designed to provide a basic model that demonstrates the direct effect of weather on exposure patterns of particulate matter smaller than 2.5 microns (PM2.5) and volatile organic chemicals (VOCs). Because emissions from unconventional natural gas development (UNGD) sites are variable, a short term exposure profile is proposed that determines 6-hour assessments of emissions estimates, a time scale needed to assist physicians in the evaluation of individual exposures. The hypothetical case is based on observed conditions in shale gas development in Washington County, Pennsylvania, and on estimated emissions from facilities during gas development and production. An air exposure screening model was applied to determine the ambient concentration of VOCs and PM2.5 at different 6-hour periods of the day and night. Hourly wind speed, wind direction and cloud cover data from Pittsburgh International Airport were used to calculate the expected exposures. Fourteen months of daily observations were modeled. Higher than yearly average source terms were used to predict health impacts at periods when emissions are high. The frequency and intensity of exposures to PM2.5 and VOCs at a residence surrounded by three UNGD facilities was determined. The findings show that peak PM2.5 and VOC exposures occurred 83 times over the course of 14 months of well development. Among the stages of well development, the drilling, flaring and finishing, and gas production stages produced higher intensity exposures than the

  14. Application of laser induced electron impact ionization to the deposition chemistry in the hot-wire chemical vapor deposition process with SiH4-NH3 gas mixtures.

    Science.gov (United States)

    Eustergerling, Brett; Hèden, Martin; Shi, Yujun

    2007-11-01

    The application of a laser-induced electron impact (LIEI) ionization source in studying the gas-phase chemistry of the SiH(4)/NH(3) hot-wire chemical vapor deposition (HWCVD) system has been investigated. The LIEI source is achieved by directing an unfocused laser beam containing both 118 nm (10.5 eV) vacuum ultraviolet (VUV) and 355 nm UV radiations to the repeller plate in a time-of-flight mass spectrometer. Comparison of the LIEI source with the conventional 118 nm VUV single-photon ionization (SPI) method has demonstrated that the intensities of the chemical species with ionization potentials (IP) above 10.5 eV, e.g., H(2), N(2) and He, have been significantly enhanced with the incorporation of the LIEI source. It is found that the SPI source due to the 118 nm VUV light coexists in the LIEI source. This allows simultaneous observations of parent ions with enhanced intensity from VUV SPI and their "fingerprint" fragmentation ions from LIEI. It is, therefore, an effective tool to diagnose the gas-phase chemical species involved with both NH(3) and SiH(4) in the HWCVD reactor. In using the LIEI source to SiH(4), NH(3) and their mixtures, it has been shown that the NH(3) decomposition is suppressed with the addition of SiH(4) molecules. Examination of the NH(3) decomposition percentage and the time to reach the N(2) and H(2) steady-state intensities for various NH(3)/SiH(4) mixtures suggests that the extent of the suppression is enhanced with more SiH(4) content in the mixture. With increasing filament temperatures, the negative effect of SiH(4) becomes less important.

  15. On the predictive capabilities of CPA for applications in the chemical industry: Mulficomponent mixtures containing methyl-methacrylate, dimethyl-ether or acetic acid

    DEFF Research Database (Denmark)

    Tsivintzelis, Ioannis; Kontogeorgis, Georgios

    2014-01-01

    with acetic acid, esters, ethers and alcohols, and in this case for water-acetic acid the CPA-Huron Vidal (CPA-HV) version of the model is used. For the latter binary mixture, new CPA-HV binary parameter sets are estimated using, among others, data for activity coefficients at infinite dilutions. The modeling...... for the acetic acid-water system for which different parameter sets at different temperatures can be recommended. Even with the use of CPA-HV mixing rules, modeling of the acetic acid-water system with few interaction parameters remains a challenging task. Excellent simultaneous VLE and LLE correlation...... is obtained for complex systems such as aqueous mixtures with ethers and esters. The multicomponent results are, with a few exceptions, very satisfactory, especially for the vapor-liquid equilibrium cases. For the demanding aqueous acetic acid-water containing systems, one parameter set is recommended...

  16. Modeling of chemical processes in the low pressure capacitive RF discharges in a mixture of Ar/C2H2

    CERN Document Server

    Ariskin, D A; Alexandrov, A L; Bogaerts, A; Peeters, F M

    2008-01-01

    We study the properties of a capacitive 13.56 MHz discharge properties with a mixture of Ar/C2H2 taking into account the plasmochemistry and growth of heavy hydrocarbons. A hybrid model was developed to combine the kinetic description for electron motion and the fluid approach for negative and positive ions transport and plasmochemical processes. A significant change of plasma parameters related to injection of 5.8% portion of acetylene in argon was observed and analyzed. We found that the electronegativity of the mixture is about 30%. The densities of negatively and positively charged heavy hydrocarbons are sufficiently large to be precursors for the formation of nanoparticles in the discharge volume.

  17. Characterization of diesel oil mixtures with soy oil used for activation of engines of internal combustion; Caracterizacao de misturas de oleo diesel com oleo de soja reutilizado para acionamento de motores de combustao interna

    Energy Technology Data Exchange (ETDEWEB)

    Siqueira, Wagner da Cunha; Fernandes, Haroldo Carlos; Teixiera, Mauri Martins; Abrahao, Selma Alves; Leite, Daniel Mariano [Universidade de Vicosa, (DEA/UFV), MG (Brazil). Dept. de Engenharia Agricola], Emails: wagner.siqueira@ufv.br, haroldo@ufv.br, mauri@ufv.br, selma.abrahao@ufv.br, daniel.mariano@ufv.br

    2011-07-01

    Alternative energy sources have been studied in several countries, with emphasis on ways of obtaining and using more efficient. The objective of this work to evaluate and characterize mixtures of diesel oil (DO) with soybean oil reused (OSR), the ratios of 0, 25, 50, 75, and 100% of OSR in relation to specific gravity index viscosity and calorific value. To determine the specific gravity was used beaker, thermometer and a balance for each mixture was adjusted a regression model to estimate the bulk density as a function of temperature (25 to 90 deg C). We analyzed the viscosity of the mixtures using an orifice-type viscometer Saybolt, through regression analysis models were fit to estimate the viscosity as a function of temperature, heating the OSR 100% from 40 to 90 deg C decreased by up 90.4% to its viscosity. The tests were performed calorimetric using a bomb calorimeter determines the calorific value , the variation in calorific value followed a descending order with respect to OD with the increasing content of OSR. The OSR is efficient for use in internal combustion engines in small proportions. (author)

  18. 化学衍生-溶剂结晶法从植物甾醇混合组分中分离豆甾醇%Separation of stigmasterol from phytosterol mixture by chemical derivatization and solvent crystallization

    Institute of Scientific and Technical Information of China (English)

    杨建洪; 杨顺楷; 曾辉; 吴中柳

    2012-01-01

    To develop a process for the separation of stigmasterol from phytosterol mixture by chemical derivatization and solvent crystallization. Its performance procedure, including acetylation, bromization, debromination, and saponification of phytosterol mixture, and crystallization with solvent, was used at the gramme level on a test bench. The yield of stigmasterol is 6. 9% and the recovery rate is 45. 7%. The phytosterol mixture was separated by the method. This illustrate that the method was feasible and suitable for a pilot run.%采用化学衍生和溶剂结晶法,建立起一条从植物甾醇混合组分分离豆甾醇的技术途径.通过对植物甾醇的乙酰化,溴化-脱溴和皂化反应,并结合相应试样的重结晶操作以分离豆甾醇.利用此方法从植物甾醇混合组分分离豆甾醇,其产率为6.9%,回收率45.7%,具有生物工业应用潜力.

  19. Automated Chemical Analysis of Internally Mixed Aerosol Particles Using X-ray Spectromicroscopy at the Carbon K-Edge

    Energy Technology Data Exchange (ETDEWEB)

    Gilles, Mary K; Moffet, R.C.; Henn, T.; Laskin, A.

    2011-01-20

    We have developed an automated data analysis method for atmospheric particles using scanning transmission X-ray microscopy coupled with near edge X-ray fine structure spectroscopy (STXM/NEXAFS). This method is applied to complex internally mixed submicrometer particles containing organic and inorganic material. Several algorithms were developed to exploit NEXAFS spectral features in the energy range from 278 to 320 eV for quantitative mapping of the spatial distribution of elemental carbon, organic carbon, potassium, and noncarbonaceous elements in particles of mixed composition. This energy range encompasses the carbon K-edge and potassium L2 and L3 edges. STXM/NEXAFS maps of different chemical components were complemented with a subsequent analysis using elemental maps obtained by scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM/EDX). We demonstrate the application of the automated mapping algorithms for data analysis and the statistical classification of particles.

  20. Detailed Chemical Characterization of Unresolved Complex Mixtures (UCM) inAtmospheric Organics: Insights into Emission Sources, Atmospheric Processing andSecondary Organic Aerosol Formation

    Science.gov (United States)

    Recent studies suggest that semivolatile organic compounds (SVOCs) are important precursors to secondary organic aerosol (SOA) in urban atmospheres. However, knowledge of the chemical composition of SVOCs is limited by current analytical techniques, which are typically unable to...

  1. Chemical and microbiological assessments of the multi mixture treated by gamma radiation; Avaliacao quimica e microbiologica da multimistura tratada por irradiacao gama

    Energy Technology Data Exchange (ETDEWEB)

    Goncalves, Cinthia Graciele

    2008-07-01

    In Brazil, the multi mixture have being used since the eighties as an alternative against severe infantile malnutrition of the poorest population. However, its use is still reason of controversies mainly due to: the presence of anti nutritional factors, the microbiological quality and the nutritional value. Considering the routine use of multi mixture in the region, this work aimed to evaluate samples of multi mixture were collected in the metropolitan area of the City of Belo Horizonte/MG for determining the anti nutritional factors (phytic and oxalic acids), the microbiological quality, the centesimal and mineral composition, and still the induced effect in these factors of the gamma radiation. For the analyses, the samples passed by the process of gamma irradiation at doses of: 2, 4, 6, 8 and 10 kGy and then were evaluated anti nutritional factors (phytic acid and oxalic), the microbiological quality (yeasts and molds, Salmonella, Coagulase positive Staphylococcus, Bacillus cereus, coliform to 45 deg C) to full percentage (moisture, ash, proteins, carbohydrates and lipids) and the efficiency of the method of Paramagnetic Electronic Resonance (EPR) in the detection of irradiated samples. The mineral composition of the samples was carried out by the irradiation by Neutronic Activation. The methods used were searched in literature. The obtained results suggest that the concentration of the phytic and oxalic acids can not be appropriated for the children with severe nutritional deficit and that it would be necessary additional control in their daily ingestion due to the absorption of essential minerals. In general the samples had presented acceptable microbiological quality for consumption, except by one of it. The data of the centesimal and mineral composition, in the usually recommended portions, showed lower concentration than recommended for children. Any significant alteration in phytic and oxalic acids as well as in the centesimal composition were detected

  2. Catalyst mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Masel, Richard I.; Rosen, Brian A.

    2017-02-14

    Catalysts that include at least one catalytically active element and one helper catalyst can be used to increase the rate or lower the overpotential of chemical reactions. The helper catalyst can simultaneously act as a director molecule, suppressing undesired reactions and thus increasing selectivity toward the desired reaction. These catalysts can be useful for a variety of chemical reactions including, in particular, the electrochemical conversion of CO.sub.2 or formic acid. The catalysts can also suppress H.sub.2 evolution, permitting electrochemical cell operation at potentials below RHE. Chemical processes and devices using the catalysts are also disclosed, including processes to produce CO, OH.sup.-, HCO.sup.-, H.sub.2CO, (HCO.sub.2).sup.-, H.sub.2CO.sub.2, CH.sub.3OH, CH.sub.4, C.sub.2H.sub.4, CH.sub.3CH.sub.2OH, CH.sub.3COO.sup.-, CH.sub.3COOH, C.sub.2H.sub.6, O.sub.2, H.sub.2, (COOH).sub.2, or (COO.sup.-).sub.2, and a specific device, namely, a CO.sub.2 sensor.

  3. Hard-sphere kinetic models for inert and reactive mixtures

    Science.gov (United States)

    Polewczak, Jacek

    2016-10-01

    I consider stochastic variants of a simple reacting sphere (SRS) kinetic model (Xystris and Dahler 1978 J. Chem. Phys. 68 387-401, Qin and Dahler 1995 J. Chem. Phys. 103 725-50, Dahler and Qin 2003 J. Chem. Phys. 118 8396-404) for dense reacting mixtures. In contrast to the line-of-center models of chemical reactive models, in the SRS kinetic model, the microscopic reversibility (detailed balance) can be easily shown to be satisfied, and thus all mathematical aspects of the model can be fully justified. In the SRS model, the molecules behave as if they were single mass points with two internal states. Collisions may alter the internal states of the molecules, and this occurs when the kinetic energy associated with the reactive motion exceeds the activation energy. Reactive and non-reactive collision events are considered to be hard sphere-like. I consider a four component mixture A, B, A *, B *, in which the chemical reactions are of the type A+B\\rightleftharpoons {{A}\\ast}+{{B}\\ast} , with A * and B * being distinct species from A and B. This work extends the joined works with George Stell to the kinetic models of dense inert and reactive mixtures. The idea of introducing smearing-type effect in the collisional process results in a new class of stochastic kinetic models for both inert and reactive mixtures. In this paper the important new mathematical properties of such systems of kinetic equations are proven. The new results for stochastic revised Enskog system for inert mixtures are also provided.

  4. 40 CFR 721.5769 - Mixture of nitrated alkylated phenols.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Mixture of nitrated alkylated phenols... Substances § 721.5769 Mixture of nitrated alkylated phenols. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as a mixture of nitrated alkylated...

  5. EFFECTS OF SIMPLIFIED CHEMICAL KINETIC MODEL ON THE MICRO-FLAME STRUCTURE AND TEMPERATURE OF THE LEAN PREMIXED METHANE-AIR MIXTURES

    Directory of Open Access Journals (Sweden)

    JUNJIE CHEN

    2015-07-01

    Full Text Available The effect of simplified chemical kinetic model on the micro-flame structure, central axis and wall temperatures were investigated with different one-step global chemical kinetic mechanisms following Mantel, Duterque and Fernández-Tarrazo models. Numerical investigations of the premixed methane-air flame in the micro-channel and lean conditions were carried out to compare and analyze the effect of the comprehensive chemical kinetic mechanisms. The results indicate that one-step global chemical kinetic mechanism affects both the micro-flame shape and the combustion temperature. Among three simulation models, Mantel model allows a stable micro-flame with a bamboo shoot form, which anchor at the inlet. Duterque model gives a stable elongated micro-flame with a considerable ignition delay, and a dead zone with fluid accumulation is observed at the entrance, which may explain the very high combustion temperature and the fast reaction rate obtained, despite the micro-flame development presents a very hot spot and causes a broadening of the combustion zone. Fernández-Tarrazo model results in a rapid extinction and doesn't seem to take all the kinetic behavior into account for the appropriate micro-combustion simulations.

  6. NiO-ScSZ and Ni 0.9Mg 0.1O-ScSZ-based anodes under internal dry reforming of simulated biogas mixtures

    Science.gov (United States)

    Shiratori, Y.; Sasaki, K.

    Solid oxide fuel cells (SOFCs) with NiO-ScSZ and Ni 0.9Mg 0.1O-ScSZ-based anodes were operated by directly feeding a fuel mixture of CH 4, CO 2 and N 2 (CH 4 to CO 2 ratio of 3:2). Stable operation under constant current load (200 mA cm -2) was achieved with a NiO-ScSZ type anode during 200 h operating hours at 900 °C. Less stable operation occurred with a Ni 0.9Mg 0.1O-ScSZ type anode. In the case of SOFC with Ni 0.9Mg 0.1O-ScSZ as the anode, the methane reforming activity was higher than that with NiO-ScSZ. This was explained by change in the microstructure promoting reforming reactions. However, the addition of MgO resulted in degradation of electrochemical performance due to increase in ohmic resistance of the anode material during operation.

  7. Toxicity of environmental chemicals and their mixtures to selected aquatic organisms. Behaviour, development and biochemistry; Toxizitaet von Umweltchemikalien und deren Mischungen auf ausgewaehlte aquatische Organismen. Verhalten, Entwicklung und Biochemie

    Energy Technology Data Exchange (ETDEWEB)

    Kienle, Cornelia

    2009-04-28

    , relevant and sensitive parameters for the different research topics/questions in the present work, and can also be recommended to be used to analyse interspecific interactions. To judge on the effects of pollutants on aquatic organisms in the environment, abiotic parameters as well as mixtures of pollutants should be included. Additionally, biochemical measurements as well as behavioural tests are important, to adequately assess the toxicity of pollutants. Therefore, for an integrated understanding of the effects of chemicals on aquatic organisms, a battery of different methods as well as more realistic exposure scenarios should be taken into account. (orig.)

  8. Contaminant mixtures and repoductive health: Developmental toxicity effects in rats after mixed exposure to environmentally relevant endocrine disrupting chemicals, with focus on effects in females

    DEFF Research Database (Denmark)

    Jacobsen, Pernille Rosenskjold; Christiansen, Sofie; Hass, Ulla

    disorders or later onset adult diseases. However, experimental evidence on the effects of developmental exposure to environmentally relevant endocrine disrupting chemicals in females has been missing attention. Since chemical exposure can affect female reproductive development it is important to investigate......Background: In toxicological testing, effects of endocrine disrupters are in most cases more thoroughly investigated in males than in females. In males the hypothesis of testicu lar dysgenesis syndrome (TDS) proposes that there is a common origin in fetal life of the increase in frequency observed...... in later years of for example incidence of boys born with hypospadias and young men with low semen quality in the human male population. Furthermore, it has been observed in animal studies that exposure during fetal life to endocrine disrupters may lead to similar adverse reproductive effects. It has been...

  9. Statistical mechanics of dilute liquid mixtures of He3 in He4

    Science.gov (United States)

    Jackson, H. W.

    1982-01-01

    The Woo-Tan-Massey quantum-mechanical theory of dilute mixtures of He-3 in liquid He-4 is extended to incorporate superfluid flow. Then statistical-mechanical principles are employed to find explicit formulas for thermodyanmic and hydrodynamic properties of mixtures, such as internal energy, free energy, entropy, pressure, chemical potential, and normal-fluid and superfluid densities. This paper is the first in a planned series that applies methods originally developed for pure liquid He-4 to dilute mixtures as a means of establishing a comprehensive theory that includes a theoretical bridge between a microscopic description of the mixtures and a hydrodynamic two-fluid model. Ultimately effects of applied electric and magnetic fields on dilute solutions are also planned to be treated.

  10. [Variations in the internal pressure of the pneumatic cuffs of endotracheal tubes according to their contents and the anesthetic mixtures used. Experimental study].

    Science.gov (United States)

    de Santos, P; Castillo, J; Bogdanovich, A; Nalda, M A

    1989-01-01

    With the purpose of measuring pressure changes in the pneumatic cuffs of endotracheal tubes when the composition of the mixture of gases used for ventilation had to change for the same content, we designed a model of artificial respiration that consisted of a tube with a low pressure pneumatic cuff measuring 8.5 mm in inner diameter introduced in a replica of a human trachea, adjusted to two anesthetic bags. The cuff valve was connected to a pressure transducer by a three-ended stopcock and, after aspiration of its content, it was inflated with air, saline or nitrous oxide and oxygen at 60% up to a basal pressure of 20 mmHg. The tube was connected to a respirator adjusted to inflate 10 l/min at a rate of 15 insufflations/min of: oxygen 100% for 5 minutes, then nitrous oxide and oxygen at 60% for 30 minutes and oxygen 100% again for 15 minutes. When inflating the pneumatic cuff with air and ventilating with nitrous oxide and oxygen at 60%, its pressure reached a maximum mean value of 58 mmHg (190% with respect to base values). When insufflating with saline and ventilating in the same conditions, pressure reached a maximum mean value of 33 mmHg (65% with respect to base values). When the pneumatic cuff was inflated with nitrous oxide and oxygen at 60%, important changes in pressure were observed when the characteristics of the inspired gases were modified. We conclude that some method for monitoring pneumatic cuff pressure should be systematized.

  11. Adsorption and chemical reaction of gaseous mixtures of hydrogen chloride and water on aluminum oxide and application to solid-propellant rocket exhaust clouds

    Science.gov (United States)

    Cofer, W. R., III; Pellett, G. L.

    1978-01-01

    Hydrogen chloride (HCl) and aluminum oxide (Al2O3) are major exhaust products of solid rocket motors (SRM). Samples of calcination-produced alumina were exposed to continuously flowing mixtures of gaseous HCl/H2O in nitrogen. Transient sorption rates, as well as maximum sorptive capacities, were found to be largely controlled by specific surface area for samples of alpha, theta, and gamma alumina. Sorption rates for small samples were characterized linearly with an empirical relationship that accounted for specific area and logarithmic time. Chemisorption occurred on all aluminas studied and appeared to form from the sorption of about a 2/5 HCl-to-H2O mole ratio. The chemisorbed phase was predominantly water soluble, yielding chloride/aluminum III ion mole ratios of about 3.3/1 suggestive of dissolved surface chlorides and/or oxychlorides. Isopiestic experiments in hydrochloric acid indicated that dissolution of alumina led to an increase in water-vapor pressure. Dissolution in aqueous SRM acid aerosol droplets, therefore, might be expected to promote evaporation.

  12. Influences of Mixture Composition on Waste Heat Recovery System for Vehicle Internal Combustion Engine%混合工质对车用内燃机余热回收系统的影响

    Institute of Scientific and Technical Information of China (English)

    周启顺; 杨凯; 张红光

    2014-01-01

    通过试验对1台标定功率为280 kW的车用内燃机全工况范围内排气能量的变化规律进行了分析,设计了一套有机朗肯循环余热回收系统,研究了车用内燃机不同工况下有机朗肯循环余热回收系统的工作性能。以典型干工质R245fa和典型湿工质R152a为组元,配制了3种不同类型的非共沸混合工质,研究了变浓度非共沸混合工质对车用内燃机有机朗肯循环余热回收系统性能的影响。研究结果表明,随着车用内燃机转速和扭矩的增加,有机朗肯循环余热回收系统的净输出功率、余热回收效率及所需的非共沸混合工质的质量流量均逐渐增加;R152a含量最高的非共沸混合工质性能最优。%The exhaust energy of 280 kW vehicle internal combustion engine in the whole conditions was analyzed by the ex-periment .A set of organic Rankine cycle system was designed and its working performance was analyzed under different engine operating conditions .Based on R245fa dry substance and R152a wet substance ,three zeotropic mixtures were prepared .The influence of zeotropic mixtures with different composition on the organic Rankine cycle waste heat recovery system performance was investigated .The results showed that the net power output ,waste heat recovery efficiency and required zerotropic mixture mass flow of organic Rankine cycle system increased gradually with the increase of engine speed and torque .The performance of zeotropic mixture containing the highest content of R152a was optimal .

  13. The Gaia-ESO Survey: the chemical structure of the Galactic discs from the first internal data release

    CERN Document Server

    Mikolaitis, Š; Recio-Blanco, A; de Laverny, P; Prieto, C Allende; Kordopatis, G; Tautvaišiene, G; Romano, D; Gilmore, G; Randich, S; Feltzing, S; Micela, G; Vallenari, A; Alfaro, E J; Bensby, T; Bragaglia, A; Flaccomio, E; Lanzafame, A C; Pancino, E; Smiljanic, R; Bergemann, M; Carraro, G; Costado, M T; Damiani, F; Hourihane, A; Jofré, P; Lardo, C; Magrini, L; Maiorca, E; Morbidelli, L; Sbordone, L; Sousa, S G; Worley, C C; Zaggia, S

    2014-01-01

    Most high-resolution spectroscopic studies of the Galactic discs were mostly confined to objects in the solar vicinity. Here we aim at enlarging the volume in which individual chemical abundances are used to characterise both discs, using the first internal data release of the Gaia-ESO survey. We derive and discuss the abundances of eight elements (Mg, Al, Si, Ca, Ti, Fe, Cr, Ni, and Y). The trends of these elemental abundances with iron are very similar to those in the solar neighbourhood. We find a natural division between alpha-rich and alpha-poor stars, best seen in the bimodality of the [Mg/M] distributions in bins of metallicity, which we attribute to thick- and thin-disc sequences, respectively. With the possible exception of Al, the observed dispersion around the trends is well described by the expected errors, leaving little room for astrophysical dispersion. Using previously derived distances from Recio-Blanco et al. (2014b), we further find that the thick-disc is more extended vertically and is mor...

  14. Mixture Density Mercer Kernels

    Data.gov (United States)

    National Aeronautics and Space Administration — We present a method of generating Mercer Kernels from an ensemble of probabilistic mixture models, where each mixture model is generated from a Bayesian mixture...

  15. Determination of polycyclic aromatic hydrocarbons in fractions in asphalt mixtures using liquid chromatography coupled to mass spectrometry with atmospheric pressure chemical ionization.

    Science.gov (United States)

    Nascimento, Paulo Cicero; Gobo, Luciana Assis; Bohrer, Denise; Carvalho, Leandro Machado; Cravo, Margareth Coutinho; Leite, Leni Figueiredo Mathias

    2015-07-01

    An analytical method using liquid chromatography coupled to mass spectrometry with atmospheric pressure chemical ionization for the determination of polycyclic aromatic hydrocarbons in asphalt fractions has been developed. The 14 compounds determined, characterized by having two or more condensed aromatic rings, are expected to be present in asphalt and are considered carcinogenic and mutagenic. The parameters of the atmospheric pressure chemical ionization interface were optimized to obtain the highest possible sensitivity for all of the compounds. The limits of detection ranged from 0.5 to 346.5 μg/L and the limits of quantification ranged from 1.7 to 1550 μg/L. The method was validated against a diesel particulate extract standard reference material (NIST SRM 1975), and the obtained concentrations agreed with the certified values. The method was applied to asphalt samples after its fractionation according to ASTM D4124 and the method of Green. The concentrations of the seven polycyclic aromatic hydrocarbons quantified in the sample ranged from 0.86 mg/kg for benzo[ghi]perylene to 98.32 mg/kg for fluorene.

  16. Ultrafiltration of a polymer-electrolyte mixture

    NARCIS (Netherlands)

    Vonk, P; Noordman, T.R; Schippers, D; Tilstra, B; Wesselingh, J.A

    1997-01-01

    We present a mathematical model to describe the ultrafiltration behaviour of polymer-electrolyte mixtures. The model combines the proper thermodynamic forces (pressure, chemical potential and electrical potential differences) with multicomponent diffusion theory. The model is verified with experimen

  17. Determination of oxygen and nitrogen derivatives of polycyclic aromatic hydrocarbons in fractions of asphalt mixtures using liquid chromatography coupled to mass spectrometry with atmospheric pressure chemical ionization.

    Science.gov (United States)

    Nascimento, Paulo Cicero; Gobo, Luciana Assis; Bohrer, Denise; Carvalho, Leandro Machado; Cravo, Margareth Coutinho; Leite, Leni Figueiredo Mathias

    2015-12-01

    Liquid chromatography coupled to mass spectrometry with atmospheric pressure chemical ionization was used for the determination of polycyclic aromatic hydrocarbon derivatives, the oxygenated polycyclic aromatic hydrocarbons and nitrated polycyclic aromatic hydrocarbons, formed in asphalt fractions. Two different methods have been developed for the determination of five oxygenated and seven nitrated polycyclic aromatic hydrocarbons that are characterized by having two or more condensed aromatic rings and present mutagenic and carcinogenic properties. The parameters of the atmospheric pressure chemical ionization interface were optimized to obtain the highest possible sensitivity for all compounds. The detection limits of the methods ranged from 0.1 to 57.3 μg/L for nitrated and from 0.1 to 6.6 μg/L for oxygenated derivatives. The limits of quantification were in the range of 4.6-191 μg/L for nitrated and 0.3-8.9 μg/L for oxygenated derivatives. The methods were validated against a diesel particulate extract standard reference material (National Institute of Standards and Technology SRM 1975), and the obtained concentrations (two nitrated derivatives) agreed with the certified values. The methods were applied in the analysis of asphalt samples after their fractionation into asphaltenes and maltenes, according to American Society for Testing and Material D4124, where the maltenic fraction was further separated into its basic, acidic, and neutral parts following the method of Green. Only two nitrated derivatives were found in the asphalt sample, quinoline and 2-nitrofluorene, with concentrations of 9.26 and 2146 mg/kg, respectively, whereas no oxygenated derivatives were detected.

  18. Clinical Observation on Chemical Damage of Nephron and the Preventive and Therapeutic Effects of Baoshen Mixture (保肾合剂)on It

    Institute of Scientific and Technical Information of China (English)

    SONG Ting-ting; JIANG Yu-hua; LAN Xiao-zhu

    2007-01-01

    Objective: To observe the change of nephron damaged by chemotherapy and to evaluate the effect of Baoshen Mixture (保肾合剂, BSM) in protecting and treating damaged nephrons.Methods: Four hundred tumor patients with normal renal function and ready to receive chemotherapy were randomly assigned to two groups. Both groups received one cycle of chemotherapy program of 28-30 days with conventional hydratization, alkalization and chloridization. To the 200 cases in the treated group BSM was given orally thrice a day, 150 mL every time for 15 successive days and the other 200 cases in the control group were treated by chemotherapy alone. The clinical efficacy was compared after treatment, and the changed condition of damaged nephrons were monitored dynamically and compared at different time points (the 3rd, 7th, 14th and 21st day after chemotherapy)by measuring the micro-globulin β2 (β2-MG), albumin (AIb) and immunoglobulin G (IgG) levels in urine with radioimmunoassay (RIA). Results: (1) The effective rates in the treated group at the 4 time points of observation were all higher than those in the control group respectively (P<0.05 or P<0.01); (2)Less occurrence of abnormal β2-M, AIb and IgG levels on the 14th and 21st day in the treated group took place compared to that in the control group (P<0.01); (3) Urinary levels of β2-MG, AIb and IgG reached the peak on the 7th day in both groups, and then, they came down gradually and returned to the normal level on the 21 st day. However, comparison between the two groups showed that all the three parameters in the treated group on day 3, 14 and 21 were lower than the respective one at the corresponding time points in the control group (P<0.05 or P<0.01). Conclusion: The chemotherapy damage on nephron is regular in time, and reversible when treated suitably. TCM shows a marked effect in protecting and treating the damage on nephron caused by chemotherapy.

  19. Synergistic Stabilization of High Internal Phase Pickering Emulsions by a Mixture of Nanoparticle and Polymer%粒子与聚合物协同稳定高内相Pickering乳液

    Institute of Scientific and Technical Information of China (English)

    邹声文; 王朝阳; 魏增江; 刘浩; 童真

    2012-01-01

    选用二氧化硅纳米粒子(H30)和聚(乳酸-羟基乙酸)共聚物(PLGA)为复合稳定剂,成功制备出内相体积分数高达90%的高内相Pickering乳液.对照实验表明:单独用H30粒子作稳定剂,内相体积分数上限为75%;单独用PLGA作稳定剂,发生严重相分离,不能形成乳液.无机纳米粒子与聚合物之间的协同作用在制备高内相乳液的过程中起到了关键作用.因此,使用无机粒子和聚合物作为混合稳定剂制备高内相乳液是一种新型而有效的方法.%In this paper,we have prepared high internal phase Pickering emulsions(Pickering HIPEs) with internal phase volume fraction 90% which are stabilized by a mixture of silica nanoparticles(H30) and poly(L-lactide-co-glycolide)(PLGA).HIPEs with an internal phase volume not more than 75% could be prepared solely by H30 nanoparticles.Using PLGA as stabilizer,phase separation takes place and stable emulsions are not formed.Synergistic interaction between H30 particles and PLGA molecules plays an im-portant part in preparation of HIPEs.Using inorganic particles and polymer as co-stabilizer will be a new and effective method to prepare HIPEs.

  20. Performance evaluation of small scale internal combustion engine with mixtures for diesel oil-palm oil; Avaliacao do desempenho do motor de combustao interna de pequeno porte com misturas oleo diesel - oleo de dende

    Energy Technology Data Exchange (ETDEWEB)

    Seye, Omar; Souza, Rubem Cesar Rodrigues [Universidade Federal do Amazonas (CDEAM/UFAM), Manaus, AM (Brazil). Centro de Desenvolvimento Energetico Amazonico], Emails: Seye62omar@yahoo.com, rcsouza@internext.com.br

    2006-07-01

    This work aims at the performance evaluation of the Cummins 4B -3.9, an internal combustion engine of maximum power 75 hp (56.6 kW) for small scale power generation, burning different mixtures of diesel fuel and palm oil. The palm oil in nature is mixed manually, what unfortunately will influence the engine performance as it hinders the combustion. The test protocol will include the biodiesel, later on. The emissions were assessed for several proportions of mixture diesel/palm oil covering the strip from 0 to 20% and the results were compared to the engine performance when it operates with diesel only. The motor is coupled to a dynamometer, whose operation consists of the acceleration and deceleration of water in order to simulate the effect of a load being applied to the motor. The system is controlled by the software LT commander that allows the start up and the shutdown of the engine from the screen of the computer that also monitors the following parameters as speed of rotation of the motor (RPM), applied torque (N-m), potency (hp), temperature of the lubricating oil, temperature of the water in the entrance and exit of the motor, and temperature of the environment (deg C), pressures of the lubricating oil and of opening of the injector (mBar). While a flow meter coupled to the piping measures the consumption of fuel, the gas analyzer ECHO Line 6000 it monitors the concentration and temperature of carbon monoxide (CO) (ppm), nitric oxide (NO) (ppm), nitrogen dioxide (NO{sub 2}), (ppm), sulfur dioxide (SO{sub 2}) (ppm) and Oxygen (O{sub 2}) (%) in the exhaust gases. This equipment also determines the combustion parameters as excess of air and the efficiency. The technical results present the efficiency variation, the pressure of the fuel, monoxide carbon, NOx emissions, Oxygen content in the exhaust gases, for the different mixture proportions. Furthermore, the results of economic viability show generation cost values of US$ 135,66/MWh for the motor operating

  1. International Conference on Harmonisation; guidance on Q6A specifications: test procedures and acceptance criteria for new drug substances and new drug products: chemical substances. Notice.

    Science.gov (United States)

    2000-12-29

    The Food and Drug Administration (FDA) is publishing a guidance entitled "Q6A Specifications: Test Procedures and Acceptance Criteria for New Drug Substances and New Drug Products: Chemical Substances." The guidance was prepared under the auspices of the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH). The guidance describes or provides recommendations concerning the selection of test procedures and the setting and justification of acceptance criteria for new chemical drug substances and new drug products produced from them. The guidance is intended to assist in the establishment of a single set of global specifications for new drug substances and new drug products.

  2. Hypolipidaemic effect of vegetable and cereal dietary mixtures from Egyptian sources

    Energy Technology Data Exchange (ETDEWEB)

    Rashed, M. M.; Shallan, M.; Mohamed, D. A.; Fouda, K.; Hanna, L. M.

    2010-07-01

    Hyperlipidaemia is a predominant risk factor for atherosclerosis and associated cardiovascular diseases (CVD). The international guidelines issued by the World Health Organization recommend a reduction in dietary saturated fat and cholesterol intake as a means to prevent hypercholesterolemia and CVD; however, only limited data are available on the benefits of vegetable consumption on CVD risk factors. The aim of this study was to prepare two powder mixtures containing vegetables and cereals and to evaluate their effect in hyperlipidaemic rats. The first mixture was prepared from whole wheat, cabbage, parsley and pepper, while the second mixture was prepared from whole wheat, red beet root, parsley and pepper. Whole wheat was used as a source of dietary fiber, while cabbage and beetroot were used as sources of glucosinolates (GLS) and betalains respectively as well as dietary fiber. The chemical compositions of these mixtures were determined. The safety of these mixtures was also evaluated by examining liver and kidney functions. The chemical compositions of the powder mixtures revealed that mixtures (1) and (2) contain 19.1% and 13.3% protein, 2.1% and 2.5 % fat, 69.6% and 77.5% carbohydrates, 1.8% and 1.2% crude fibers, 7.4% and 5.5% ash and 18.3% and 16.8% dietary fibers respectively. Vitamin E was 7.4 and 4.5 mg/100g in mixtures (1) and (2) respectively. {beta}-carotene was 830 and 786{mu}g/100g in mixtures (1) and (2) respectively. Total phenolic compounds were 1910 and 1710 mg as gallic acid equivalents/100g in mixtures (1) and (2) respectively. The results of the animal experiment showed a non-significant reduction in final body weight and body weight gain in rats fed the control diet containing mixture (1) or (2) when compared with different groups. Rats fed the control diet containing mixture (1) or (2) showed a significant reduction in plasma total lipids, T-Ch, LDL-Ch, TG and the ratio of T-Ch /HDLCh in different degrees, while HDL-Ch increased

  3. The ECVAM international validation study on in vitro tests for acute skin irritation: selection of test chemicals.

    Science.gov (United States)

    Eskes, Chantra; Cole, Thomas; Hoffmann, Sebastian; Worth, Andrew; Cockshott, Amanda; Gerner, Ingrid; Zuang, Valérie

    2007-12-01

    The ECVAM-funded skin irritation validation study (SIVS) was initiated in 2003, with the aim to evaluate whether the EpiDerm, EPISKIN and the SIFT alternative methods were able to reliably identify skin irritant and non-irritant chemicals, and could therefore be candidates for replacing the rabbit Draize test for skin irritation. The primary goal of the study was to evaluate the predictive capacity of the assays with regard to the EU classification system, which employs the risk phrases, "R38", for skin irritants, and "no label" for non-irritants. A secondary objective was the retrospective analysis of the data, to assess whether the in vitro tests would be able to discriminate between strong irritants (category 2), mild irritants (category 3) and non-irritants (no category), as defined by the OECD and United Nations proposal for a Globally Harmonised System (GHS) for the classification and labelling of dermal irritancy. A Chemicals Selection Sub-Committee (CSSC) was appointed to identify test chemicals to be used in the SIVS, for which existing, high quality in vivo data were available, with which to correlate the in vitro measurements. Since chemicals from the European Centre for the Ecotoxicology and Toxicology of Chemicals (ECETOC) database of reference chemicals for skin irritation/skin corrosion had been extensively used in preceding studies, the CSSC made use of novel sources for potential test chemicals. The first source of chemicals screened was the New Chemicals Database (NCD), which is the central archive within the EU notification scheme for 'new' commercial chemicals. Data registered in the NCD originate from standard assays, submitted in compliance with the legislation which regulates the marketing of industrial chemicals, and are subject to quality assurance by the competent authorities of the EU Member States. In addition, to obtain 'existing' chemicals which were readily available from major manufacturing and/or distribution sources, additional

  4. Pheromones and signature mixtures: defining species-wide signals and variable cues for identity in both invertebrates and vertebrates.

    Science.gov (United States)

    Wyatt, Tristram D

    2010-10-01

    Pheromones have been found in species in almost every part of the animal kingdom, including mammals. Pheromones (a molecule or defined combination of molecules) are species-wide signals which elicit innate responses (though responses can be conditional on development as well as context, experience, and internal state). In contrast, signature mixtures, in invertebrates and vertebrates, are variable subsets of molecules of an animal's chemical profile which are learnt by other animals, allowing them to distinguish individuals or colonies. All signature mixtures, and almost all pheromones, whatever the size of molecules, are detected by olfaction (as defined by receptor families and glomerular processing), in mammals by the main olfactory system or vomeronasal system or both. There is convergence on a glomerular organization of olfaction. The processing of all signature mixtures, and most pheromones, is combinatorial across a number of glomeruli, even for some sex pheromones which appear to have 'labeled lines'. Narrowly specific pheromone receptors are found, but are not a prerequisite for a molecule to be a pheromone. A small minority of pheromones act directly on target tissues (allohormone pheromones) or are detected by non-glomerular chemoreceptors, such as taste. The proposed definitions for pheromone and signature mixture are based on the heuristic value of separating these kinds of chemical information. In contrast to a species-wide pheromone, there is no single signature mixture to find, as signature mixtures are a 'receiver-side' phenomenon and it is the differences in signature mixtures which allow animals to distinguish each other.

  5. 随机取向内外混合凝聚粒子辐射特性%Radiative properties of internal/external mixture of agglomerates in random orientation

    Institute of Scientific and Technical Information of China (English)

    类成新; 吴振森; 冯东太

    2013-01-01

    The discrete dipole approximation method was used to compute the radiative characteristic parameters including the optical cross-sections, single-scattering albedo and asymmetrical parameter for a variety of mixed agglomerates in different mixing states at a visible wavelength 0.55μm. It is shown that the influence of the mixing states on the asymmetrical parameter is very great, and that on the scattering cross section and single-scattering albedo is heavy, while that on the absorption and extinction cross sections is not obvious. The influence of mixing patterns on the asymmetrical parameter, scattering cross section and single-scattering albedo is becoming more obvious with the increase of the size of agglomerates. The mixture ratios has an obvious effect on the radiative characteristic quantities of agglomerates in internal and external mixing states, and the effect varies with the monomer diameters, and number of monomers in the agglomerates. The scattering cross-sections of external mixture of agglomerates are larger than those of their internally mixed counterparts, but the single-scattering albedo decreases accordingly at the same mixture ratios.%采用离散偶极子近似方法对随机取向混合凝聚粒子在内外混合状态下的光学截面、单次散射反照率以及非对称因子等辐射特性参量进行了数值计算,详细讨论了混合方式、混合比等因素对混合凝聚粒子辐射特性的影响。研究表明,混合凝聚粒子的混合方式对非对称因子的影响非常大,对散射截面和单次散射反照率的影响比较大,但是对吸收和消光截面的影响不明显。随着凝聚粒子中基本粒子粒径和数量的增大,非对称因子、散射截面以及单次散射反照率受混合方式的影响变得愈加明显。此外,混合比的变化对不同混合状态下的凝聚粒子的辐射特性参量均存在不同程度的影响,并且此影响随着基本粒子粒径和数量的变

  6. Optimal mixture experiments

    CERN Document Server

    Sinha, B K; Pal, Manisha; Das, P

    2014-01-01

    The book dwells mainly on the optimality aspects of mixture designs. As mixture models are a special case of regression models, a general discussion on regression designs has been presented, which includes topics like continuous designs, de la Garza phenomenon, Loewner order domination, Equivalence theorems for different optimality criteria and standard optimality results for single variable polynomial regression and multivariate linear and quadratic regression models. This is followed by a review of the available literature on estimation of parameters in mixture models. Based on recent research findings, the volume also introduces optimal mixture designs for estimation of optimum mixing proportions in different mixture models, which include Scheffé’s quadratic model, Darroch-Waller model, log- contrast model, mixture-amount models, random coefficient models and multi-response model.  Robust mixture designs and mixture designs in blocks have been also reviewed. Moreover, some applications of mixture desig...

  7. Commandant’s International Technical Series. Volume 9. International Regulations on the Prevention of Pollution from Ships Carrying Hazardous Chemicals in Bulk.

    Science.gov (United States)

    1985-12-01

    8217- line draining and stripping or blowing arrangements; and - quantity and pressure of nitrogen or air required for line blowing if applicable. LA-- . MEPC...response to resolution 15 of the International Confecence on Marine Polution , 1973, the Marine Environment Protection Committee at its twenty-second...content of these spaces should be maintained below 2%. Portable sampling equipment is satisfactory. * 15.8.19 In no case should air be allowed to

  8. Simultaneous and selective decarboxylation of L-serine and deamination of L-phenylalanine in an amino acid mixture--a means of separating amino acids for synthesizing biobased chemicals.

    Science.gov (United States)

    Teng, Yinglai; Scott, Elinor L; Witte-van Dijk, Susan C M; Sanders, Johan P M

    2016-01-25

    Amino acids (AAs) obtained from the hydrolysis of biomass-derived proteins are interesting feedstocks for the chemical industry. They can be prepared from the byproduct of biofuel production and agricultural wastes. They are rich in functionalities needed in petrochemicals, providing the opportunity to save energy, reagents, and process steps. However, their separation is required before they can be applied for further applications. Electrodialysis (ED) is a promising separation method, but its efficiency needs to be improved when separating AAs with similar isoelectric points. Thus, specific conversions are required to form product with different charges. Here we studied the enzymatic conversions which can be used as a means to aid the ED separation of neutral AAs. A model mixture containing L-serine, L-phenylalanine and L-methionine was used. The reactions of L-serine decarboxylase and L-phenylalanine ammonia-lyase were employed to specifically convert serine and phenylalanine into ethanolamine and trans-cinnamic acid. At the isoelectric point of methionine (pH 5.74), the charge of ethanolamine and trans-cinnamic acid are +1 and -1, therefore facilitating potential separation into three different streams by electrodialysis. Here the enzyme kinetics, specificity, inhibition and the operational stabilities were studied, showing that both enzymes can be applied simultaneously to aid the ED separation of neutral AAs.

  9. Predicted no effect concentration derivation as a significant source of variability in environmental hazard assessments of chemicals in aquatic systems: an international analysis.

    Science.gov (United States)

    Hahn, Thorsten; Diamond, Jerry; Dobson, Stuart; Howe, Paul; Kielhorn, Janet; Koennecker, Gustav; Lee-Steere, Chris; Mangelsdorf, Inge; Schneider, Uwe; Sugaya, Yoshio; Taylor, Ken; Dam, Rick Van; Stauber, Jenny L

    2014-01-01

    Environmental hazard assessments for chemicals are carried out to define an environmentally "safe" level at which, theoretically, the chemical will not negatively affect any exposed biota. Despite this common goal, the methodologies in use are very diverse across different countries and jurisdictions. This becomes particularly obvious when international scientists work together on documents with global scope, e.g., in the World Health Organization (WHO) International Program on Chemical Safety. In this article, we present a study that describes the extent of such variability and analyze the reasons that lead to different outcomes in deriving a "safe level" (termed the predicted no effect concentration [PNEC] throughout this article). For this purpose, we chose 5 chemicals to represent well-known substances for which sufficient high-quality aquatic effects data were available: ethylene glycol, trichloroethylene, nonylphenol, hexachlorobenzene, and copper (Cu). From these data, 2 data sets for each chemical were compiled: the full data set, that contained all information from selected peer-review sources, and the base data set, a subsample of the full set simulating limited data. Scientists from the European Union (EU), United States, Canada, Japan, and Australia independently carried out hazard assessments for each of these chemicals using the same data sets. Their reasoning for key study selection, use of assessment factors, or use of probabilistic methods was comprehensively documented. The observed variation in the PNECs for all chemicals was up to 3 orders of magnitude, and this was not simply due to obvious factors such as the size of the data set or the methodology used. Rather, this was due to individual decisions of the assessors within the scope of the methodology used, especially key study selection, acute versus chronic definitions, and size of assessment factors. Awareness of these factors, together with transparency of the decision-making process, would

  10. Low temperature asphalt mixtures

    OpenAIRE

    Modrijan, Damjan

    2006-01-01

    This thesis presents the problem of manufacturing and building in the asphalt mixtures produced by the classical hot procedure and the possibility of manufacturing low temperature asphalt mixtures.We will see the main advantages of low temperature asphalt mixtures prepared with bitumen with organic addition Sasobit and compare it to the classical asphalt mixtures. The advantages and disadvantages of that are valued in the practical example in the conclusion.

  11. Exposure to Pb, Cd, and As mixtures potentiates the production of oxidative stress precursors: 30-day, 90-day, and 180-day drinking water studies in rats.

    Science.gov (United States)

    Whittaker, Margaret H; Wang, Gensheng; Chen, Xue-Qing; Lipsky, Michael; Smith, Donald; Gwiazda, Roberto; Fowler, Bruce A

    2011-07-15

    Exposure to chemical mixtures is a common and important determinant of toxicity and is of particular concern due to their appearance in sources of drinking water. Despite this, few in vivo mixture studies have been conducted to date to understand the health impact of chemical mixtures compared to single chemicals. Interactive effects of lead (Pb), cadmium (Cd) and arsenic (As) were evaluated in 30-, 90-, and 180-day factorial design drinking water studies in rats designed to test the hypothesis that ingestion of such mixtures at individual component Lowest-Observed-Effect-Levels (LOELs) results in increased levels of the pro-oxidant delta aminolevulinic acid (ALA), iron, and copper. LOEL levels of Pb, Cd, and As mixtures resulted in the increased presence of mediators of oxidative stress such as ALA, copper, and iron. ALA increases were followed by statistically significant increases in kidney copper in the 90- and 180-day studies. Statistical evidence of interaction was identified for six biologically relevant variables: blood delta aminolevulinic acid dehydratase (ALAD), kidney ALAD, urinary ALA, urinary iron, kidney iron, and kidney copper. The current investigations underscore the importance of considering interactive effects that common toxic agents such as Pb, Cd, and As may have upon one another at low-dose levels. The interactions between known toxic trace elements at biologically relevant concentrations shown here demonstrate a clear need to rigorously review methods by which national/international agencies assess health risks of chemicals, since exposures may commonly occur as complex mixtures.

  12. Liquids and liquid mixtures

    CERN Document Server

    Rowlinson, J S; Baldwin, J E; Buckingham, A D; Danishefsky, S

    2013-01-01

    Liquids and Liquid Mixtures, Third Edition explores the equilibrium properties of liquids and liquid mixtures and relates them to the properties of the constituent molecules using the methods of statistical thermodynamics. Topics covered include the critical state, fluid mixtures at high pressures, and the statistical thermodynamics of fluids and mixtures. This book consists of eight chapters and begins with an overview of the liquid state and the thermodynamic properties of liquids and liquid mixtures, including vapor pressure and heat capacities. The discussion then turns to the thermodynami

  13. Electrochemical study of chemical properties in ethanolamine and its mixtures with water; Etude electrochimique de proprietes chimiques dans l'ethanolamine et ses melanges avec l'eau

    Energy Technology Data Exchange (ETDEWEB)

    Grall, M. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1964-12-01

    This work is concerned with the study of acid-base reactions and of complex formation in ethanolamine and its mixtures with water. The ionic product of the solvent has been determined by an electro-chemical study of the H{sup +}/H{sub 2} system. The reduction curves for ethanolamine-water mixtures, for different acidities, have made it possible to follow the variations in the size of the pH domain as a function of the composition of the solvent. The form of this variation has been explained on the basis of the dielectric constant and the solvation of the proton by the ethanolamine. In the second part, the electrochemical systems of mercury have been studied by anodic polarography. In order to establish a parallel between the acid-base reactions and complex formation reactions, we have studied the stability of Hg (CN){sub 2} in water-ethanolamine mixtures. It has been possible to deduce the law for the variation of pK{sub c} with solvent composition. The representative graph of this function passes through a minimum for a proportion of about 50 per cent of ethanolamine as in the case of acids. This variation has been explained by the predominating influence of {epsilon} for ethanolamine propositions of over 50 per cent and by that of the solvation of Hg{sup 2+} for proportions of under 50 per cent. (author) [French] Ce travail porte sur l'etude des reactions acides-bases et de formation de complexes dans l'ethanolamine et ses melanges avec l'eau. Le produit ionique du solvant a pu etre determine par l'etude electro-chimique du systeme H{sup +}/H{sub 2}. Les courbes de reduction des melanges ethanolamine-eau, pour des acidites variables, ont permis de suivre les variations de l'etendue du domaine de pH, en fonction de la composition du solvant. L'allure de cette variation a ete expliquee en faisant intervenir la constante dielectrique et la solvatation du proton par l'ethanolamine. Dans une deuxieme partie, les systemes

  14. [Harmonization with international approaches to guidance documents on methods of assessment of the mutagenic properties of chemical environmental factors].

    Science.gov (United States)

    Zhurkov, V S; Sycheva, L P; Ingel', F I; Akhal'tseva, L V; Iurchenko, V V

    2013-01-01

    Evaluation of mutagenic activity--an indispensable element of the toxicological characteristics of chemicals in their hygienic regulation. In the article there is performed an analysis of the adopted in the Organization for Economic Cooperation and Development (OECD) and in Russia guidance documents on methods of assessment of the mutagenic properties of chemicals. In the OECD there are 17 manuals, each of which describes a single method, in Russia there were approved five guidance documents for specific groups of chemicals (drugs, pesticides, nanomaterials, substances normalized in the water and the air), which represent the basic and auxiliary methods of testing mutagens. Basic methods aimed to the evaluation of gene, chromosomal and genomic mutations include: assessment of gene mutations in bacteria, methods for estimating mutations in cell cultures of human and mammals in vitro, methods for inspecting mutations in somatic and germ cells of mammals in vivo. Analysis of Russian documents shows that the protocols of basic tests of assessment of the mutagenic activity are close to the protocols of the OECD. It is necessary to publish guidance documents on tests of assessment of the mutagenic activity of chemicals harmonized with the OECD documents.

  15. Novel Folding Large-Scale Optical Switch Matrix with Total Internal Reflection Mirrors on Silicon-on-Insulator by Anisotropy Chemical Etching

    Institute of Scientific and Technical Information of China (English)

    LIU Jing-Wei; YU Jin-Zhong; CHEN Shao-Wu

    2005-01-01

    A compact optical switch matrix was designed, in which light circuits were folded by total internal reflective (TIR) mirrors. Two key elements, 2 × 2 switch and TIR mirror, have been fabricated on silicon-on-insulator wafer by anisotropy chemical etching. The 2 × 2 switch showed very low power consumption of 140mW and avery high speed of 8 ± 1 μs. An improved design for the TIR mirror was developed, and the fabricated mirror with smooth and vertical reflective facet showed low excess loss of 0.7 ± 0.3 dB at 1.55μm.

  16. An approach based on ultrahigh performance liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry allowing the quantification of both individual phytosteryl and phytostanyl fatty acid esters in complex mixtures.

    Science.gov (United States)

    Scholz, Birgit; Menzel, Nicole; Lander, Vera; Engel, Karl-Heinz

    2016-01-15

    A method for the analysis of both individual phytosteryl and phytostanyl fatty acid esters in complex mixtures was established. The approach was based on a previously not described combination of three elements: (i) the formation of [M-FA+H](+) fragment ions via APCI (atmospheric pressure chemical ionization), (ii) a highly efficient UHPLC-based separation on a 1.7 μ C8 column, previously established for phytostanyl fatty acid esters, allowing the distinction of individual fatty acid esters sharing the same sterol/stanol nucleus and of isotope peaks of phytosteryl fatty acid esters and corresponding phytostanyl fatty acid esters based on these [M-FA+H](+) fragment ions, and (iii) the adjustment of the APCI conditions allowing the differential APCI-MS-SIM (single ion monitoring) detection of phytostanyl esters of linoleic and linolenic acid based on their distinct formation of a [M+H](+) ion. The usefulness of the methodology was demonstrated by the analysis of a commercially available enriched margarine. Two runs per sample allowed the quantification of 35 target analytes; the total amounts of esters were between 124.7 and 125.3g/kg, being in good agreement with the labelled 125 g/kg. Validation data were elaborated for 35 individual fatty acid esters of sitosterol, campesterol, brassicasterol, stigmasterol, sitostanol and campestanol. Recovery rates ranged from 95 to 106%; the coefficients of variation were consistently quantification of both individual phytosteryl and phytostanyl fatty acid esters and thus closes an analytical gap related to this class of health-relevant food constituents.

  17. Systems and methods for removing components of a gas mixture

    Science.gov (United States)

    None

    2016-09-06

    A system for removing components of a gaseous mixture is provided comprising: a reactor fluid containing vessel having conduits extending therefrom, aqueous fluid within the reactor, the fluid containing a ligand and a metal, and at least one reactive surface within the vessel coupled to a power source. A method for removing a component from a gaseous mixture is provided comprising exposing the gaseous mixture to a fluid containing a ligand and a reactive metal, the exposing chemically binding the component of the gaseous mixture to the ligand. A method of capturing a component of a gaseous mixture is provided comprising: exposing the gaseous mixture to a fluid containing a ligand and a reactive metal, the exposing chemically binding the component of the gaseous mixture to the ligand, altering the oxidation state of the metal, the altering unbinding the component from the ligand, and capturing the component.

  18. Laser-assisted one-pot fabrication of calcium phosphate-based submicrospheres with internally crystallized magnetite nanoparticles through chemical precipitation.

    Science.gov (United States)

    Nakamura, Maki; Oyane, Ayako; Sakamaki, Ikuko; Ishikawa, Yoshie; Shimizu, Yoshiki; Kawaguchi, Kenji

    2015-04-14

    In this paper, we have further developed our simple (one-pot) and rapid (short irradiation time) laser fabrication process of submicrometer spheres composed of amorphous calcium iron phosphate. In our previous process, laser irradiation was applied to a calcium phosphate (CaP) reaction mixture supplemented with ferric ions (Fe(3+)) as a light-absorbing agent. Because the intention of the present study was to fabricate magnetite-encapsulated CaP-based submicrometer spheres, ferrous ions (Fe(2+)) were used as a light-absorbing agent rather than ferric ions. The ferrous ions served as a light-absorbing agent and facilitated the fabrication of submicrometer and micrometer spheres of amorphous calcium iron phosphate. The sphere formation and growth were better promoted by the use of ferrous ions as compared with the use of ferric ions. The chemical composition of the spheres was controllable through adjustment of the experimental conditions. By the addition of sodium hydroxide to the CaP reaction mixture supplemented with ferrous ions, fabrication of CaP-based magnetic submicrometer spheres was successfully achieved. Numerous magnetite and wüstite nanoparticles were coprecipitated or segregated into the CaP-based spherical amorphous matrix via light-material interaction during the CaP precipitation process. The magnetic properties of the magnetite and wüstite formed in the CaP-based spheres were investigated by magnetization measurements. The present process and the resulting CaP-based spheres are expected to have great potential for biomedical applications.

  19. Fracture Toughness, Mechanical Property, And Chemical Characterization Of A Critical Modification To The NASA SLS Solid Booster Internal Material System

    Science.gov (United States)

    Pancoast, Justin; Garrett, William; Moe, Gulia

    2015-01-01

    A modified propellant-liner-insulation (PLI) bondline in the Space Launch System (SLS) solid rocket booster required characterization for flight certification. The chemical changes to the PLI bondline and the required additional processing have been correlated to mechanical responses of the materials across the bondline. Mechanical properties testing and analyses included fracture toughness, tensile, and shear tests. Chemical properties testing and analyses included Fourier transform infrared (FTIR) spectroscopy, cross-link density, high-performance liquid chromatography (HPLC), gas chromatography (GC), gel permeation chromatography (GPC), and wave dispersion X-ray fluorescence (WDXRF). The testing identified the presence of the expected new materials and found the functional bondline performance of the new PLI system was not significantly changed from the old system.

  20. Reduced chemical reaction mechanisms: experimental and HCCI modelling investigations of autoignition processes of iso-octane in internal combustion engines

    OpenAIRE

    Machrafi, Hatim; Lombaert, K.; Cavadias, S; Guibert, P.; Amouroux, J

    2005-01-01

    A semi-reduced (70 species, 210 reactions) and a skeletal (27 species, 29 reactions) chemical reaction mechanism for iso-octane are constructed from a semi-detailed iso-octane mechanism (84 species, 412 reactions) of the Chalmers University of Technology in Sweden. The construction of the reduced mechanisms is performed by using reduction methods such as the quasi-steady-state assumption and the partial equilibrium assumption. The obtained reduced iso-octane mechanisms show, at the mentioned ...

  1. An international network (PlaNet) to evaluate a human placental testing platform for chemicals safety testing in pregnancy

    DEFF Research Database (Denmark)

    Brownbill, Paul; Chernyavsky, Igor; Bottalico, Barbara;

    2016-01-01

    in pregnancy and how ex vivo and in vitro human placental models might be advanced to reproducible human placental test systems (HPTSs), refining a weight of evidence to the guidance given around compound risk assessment during pregnancy. The placental pharmacokinetics of xenobiotic transfer, dysregulated...... placental function in pregnancy-related pathologies and influx/efflux transporter polymorphisms are a few caveats that could be addressed by HPTSs, not the specific focus of current mammalian reproductive toxicology systems. An international consortium, “PlaNet”, will bridge academia, industry...... and regulators to consider screen ability and standardisation issues surrounding these models, with proven reproducibility for introduction into industrial and clinical practice....

  2. Comparison of chemical washing and physical cell-disruption approaches to assess the surface adsorption and internalization of cadmium by Cupriavidus metallidurans CH34

    Energy Technology Data Exchange (ETDEWEB)

    Desaunay, Aurélien; Martins, Jean M.F., E-mail: jean.martins@ujf-grenoble.fr

    2014-05-01

    Highlights: • Subcellular distribution of cadmium in Cupriavidus metallidurans CH34 cells. • Comparison of a chemical (EDTA washing) and a physical method (physical disruption). • EDTA washings strongly overestimated membrane-bound Cd concentrations. • The physical method revealed surprisingly over 80% of Cd internalization in the cells. • Metal biosorption by bacteria cannot be considered as a surface complexation process. - Abstract: Bacterial biosorption of heavy metals is often considered as a surface complexation process, without considering other retention compartments than cell walls. Although this approach gives a good description of the global biosorption process, it hardly permits the prediction of the fate of biosorbed metals in the environment. This study examines the subcellular distribution of cadmium (Cd) in the metal-tolerant bacterium Cupriavidus metallidurans CH34 through the comparison of an indirect chemical method (washing cells with EDTA) and a direct physical method (physical disruption of cells). The chemical washing approach presented strong experimental biases leading to the overestimation of washed amount of Cd, supposedly bound to cell membranes. On the contrary, the physical disruption approach gave reproducible and robust results of Cd subcellular distribution. Unexpectedly, these results showed that over 80% of passively biosorbed Cd is internalized in the cytoplasm. In disagreement with the common concept of surface complexation of metals onto bacteria the cell wall was poorly reactive to Cd. Our results indicate that metal sorption onto bacterial surfaces is only a first step in metal management by bacteria and open new perspectives on metal biosorption by bacteria in the environment, with implications for soil bioremediation or facilitated transport of metals by bacteria.

  3. D-OPTIMAL EXPERIMENTAL DESIGNS TO TEST FOR DEPARTURE FROM ADDITIVITY IN A FIXED-RATIO RAY MIXTURE.

    Science.gov (United States)

    Risk assessors are becoming increasingly aware of the importance of assessing interactions between chemicals in a mixture. Most traditional designs for evaluating interactions are prohibitive when the number of chemicals in the mixture is large. However, evaluation of interacti...

  4. Swelling of Superabsorbent Poly(Sodium-Acrylate Acrylamide) Hydrogels and Influence of Chemical Structure on Internally Cured Mortar

    Science.gov (United States)

    Krafcik, Matthew J.; Erk, Kendra A.

    Superabsorbent hydrogel particles show promise as internal curing agents for high performance concrete (HPC). These gels can absorb and release large volumes of water and offer a solution to the problem of self-dessication in HPC. However, the gels are sensitive to ions naturally present in concrete. This research connects swelling behavior with gel-ion interactions to optimize hydrogel performance for internal curing, reducing the chance of early-age cracking and increasing the durability of HPC. Four different hydrogels of poly(sodium-acrylate acrylamide) are synthesized and characterized with swelling tests in different salt solutions. Depending on solution pH, ionic character, and gel composition, diffrerent swelling behaviors are observed. As weight percent of acrylic acid increases, gels demonstrate higher swelling ratios in reverse osmosis water, but showed substantially decreased swelling when aqueous cations are present. Additionally, in multivalent cation solutions, overshoot peaks are present, whereby the gels have a peak swelling ratio but then deswell. Multivalent cations interact with deprotonated carboxylic acid groups, constricting the gel and expelling water. Mortar containing hydrogels showed reduced autogenous shrinkage and increased relative humidity.

  5. Detailed Chemical Abundances in NGC 5824: Another Metal-Poor Globular Cluster with Internal Heavy Element Abundance Variations

    CERN Document Server

    Roederer, Ian U; Bailey, John I; Spencer, Meghin; Crane, Jeffrey D; Shectman, Stephen A

    2015-01-01

    We present radial velocities, stellar parameters, and detailed abundances of 39 elements derived from high-resolution spectroscopic observations of red giant stars in the luminous, metal-poor globular cluster NGC 5824. We observe 26 stars in NGC 5824 using the Michigan/Magellan Fiber System (M2FS) and two stars using the Magellan Inamori Kyocera Echelle (MIKE) spectrograph. We derive a mean metallicity of [Fe/H]=-1.94+/-0.02 (statistical) +/-0.10 (systematic). The metallicity dispersion of this sample of stars, 0.08 dex, is in agreement with previous work and does not exceed the expected observational errors. Previous work suggested an internal metallicity spread only when fainter samples of stars were considered, so we cannot exclude the possibility of an intrinsic metallicity dispersion in NGC 5824. The M2FS spectra reveal a large internal dispersion in [Mg/Fe], 0.28 dex, which is found in a few other luminous, metal-poor clusters. [Mg/Fe] is correlated with [O/Fe] and anti-correlated with [Na/Fe] and [Al/F...

  6. Endocrine disrupting chemicals

    DEFF Research Database (Denmark)

    Mandrup, Karen

    BACKGROUND: Endocrine disrupting chemicals (EDCs) may contribute to reproductive changes in boys in the Western world, however, less is known about influence of EDCs in women. The incidence of precocious breast development is increasing in USA and Europe and mammary gland development has been...... suggested as particularly sensitive to endocrine disruption. Mammary gland examination in toxicological studies may be useful for improving knowledge on possible influences of EDCs on human mammary glands and also be useful for detection of endocrine disrupting effects of chemicals as part of safety testing...... and genistein, a mixture of phytoestrogens, and a mixture of environmentally relevant estrogenic EDCs of various origins. Moreover, mixtures of antiandrogenic chemicals were investigated. These include a mixture of pesticides and a mixture of environmentally relevant anti-androgenic EDCs of various origins...

  7. Realistic environmental mixtures of micropollutants in surface, drinking, and recycled water: herbicides dominate the mixture toxicity toward algae.

    Science.gov (United States)

    Tang, Janet Y M; Escher, Beate I

    2014-06-01

    Mixture toxicity studies with herbicides have focused on a few priority components that are most likely to cause environmental impacts, and experimental mixtures were often designed as equipotent mixtures; however, real-world mixtures are made up of chemicals with different modes of toxic action at arbitrary concentration ratios. The toxicological significance of environmentally realistic mixtures has only been scarcely studied. Few studies have simultaneously compared the mixture effect of water samples with designed reference mixtures comprised of the ratios of analytically detected concentrations in toxicity tests. In the present study, the authors address the effect of herbicides and other chemicals on inhibition of photosynthesis and algal growth rate. The authors tested water samples including secondary treated wastewater effluent, recycled water, drinking water, and storm water in the combined algae assay. The detected chemicals were mixed in the concentration ratios detected, and the biological effects of the water samples were compared with the designed mixtures of individual detected chemicals to quantify the fraction of effect caused by unknown chemicals. The results showed that herbicides dominated the algal toxicity in these environmentally realistic mixtures, and the contribution by the non-herbicides was negligible. A 2-stage model, which used concentration addition within the groups of herbicides and non-herbicides followed by the model of independent action to predict the mixture effect of the two groups, could predict the experimental mixture toxicity effectively, but the concentration addition model for herbicides was robust and sufficient for complex mixtures. Therefore, the authors used the bioanalytical equivalency concept to derive effect-based trigger values for algal toxicity for monitoring water quality in recycled and surface water. All water samples tested would be compliant with the proposed trigger values associated with the

  8. Supercritical Water Mixture (SCWM) Experiment

    Science.gov (United States)

    Hicks, Michael C.; Hegde, Uday G.

    2012-01-01

    The subject presentation, entitled, Supercritical Water Mixture (SCWM) Experiment, was presented at the International Space Station (ISS) Increment 33/34 Science Symposium. This presentation provides an overview of an international collaboration between NASA and CNES to study the behavior of a dilute aqueous solution of Na2SO4 (5% w) at near-critical conditions. The Supercritical Water Mixture (SCWM) investigation, serves as important precursor work for subsequent Supercritical Water Oxidation (SCWO) experiments. The SCWM investigation will be performed in DECLICs High Temperature Insert (HTI) for the purpose of studying critical fluid phenomena at high temperatures and pressures. The HTI includes a completely sealed and integrated test cell (i.e., Sample Cell Unit SCU) that will contain approximately 0.3 ml of the aqueous test solution. During the sequence of tests, scheduled to be performed in FY13, temperatures and pressures will be elevated to critical conditions (i.e., Tc = 374C and Pc = 22 MPa) in order to observe salt precipitation, precipitate agglomeration and precipitate transport in the presence of a temperature gradient without the influences of gravitational forces. This presentation provides an overview of the motivation for this work, a description of the DECLIC HTI hardware, the proposed test sequences, and a brief discussion of the scientific research objectives.

  9. Two-microphone Separation of Speech Mixtures

    DEFF Research Database (Denmark)

    2006-01-01

    of Speech Mixtures," 2006, submited for journal publication. See also, [2] Michael Syskind Pedersen, DeLiang Wang, Jan Larsen and Ulrik Kjems: "Overcomplete Blind Source Separation by Combining ICA and Binary Time-Frequency Masking," in proceedings of IEEE International workshop on Machine Learning...

  10. Experiments with Mixtures Designs, Models, and the Analysis of Mixture Data

    CERN Document Server

    Cornell, John A

    2011-01-01

    The most comprehensive, single-volume guide to conducting experiments with mixtures"If one is involved, or heavily interested, in experiments on mixtures of ingredients, one must obtain this book. It is, as was the first edition, the definitive work."-Short Book Reviews (Publication of the International Statistical Institute)"The text contains many examples with worked solutions and with its extensive coverage of the subject matter will prove invaluable to those in the industrial and educational sectors whose work involves the design and analysis of mixture experiments."-Journal of the Royal S

  11. A sealing mixture

    Energy Technology Data Exchange (ETDEWEB)

    Khayrullin, S.R.; Firsov, I.A.; Ongoyev, V.M.; Shekhtman, E.N.; Taskarin, B.T.

    1983-01-01

    A plugging mixture is proposed which contains triethanolamine, caustic soda, water and an additive. It is distinguished by the fact that in order to reduce the cost of the mixture while preserving its operational qualities, it additionally contains clay powder and as the additive, ground limestone with the following component ratio in percent by mass: ground limestone, 50 to 60; triethanolamine, 0.1 to 0.15; caustic soda, 2 to 3; clay powder, 8 to 10 and water the remainder. The mixture is distinguished by the fact that the ground limestone has a specific surface of 2,000 to 3,000 square centimeters per gram.

  12. Factors that elevate the internal radionuclide and chemical retention, dose and health risks to infants and children in a radiological-nuclear emergency.

    Science.gov (United States)

    Richardson, Richard B

    2009-06-01

    The factors that influence the dose and risk to vulnerable population groups from exposure and internal uptake of chemicals are examined and, in particular, the radionuclides released in chemical, biological, radiological, nuclear and explosive events. The paper seeks to identify the areas that would benefit from further research. The intake and body burdens of carbon and calcium were assessed as surrogates for contaminants that either act like or bind to hydrocarbons (e.g. tritium and (14)C) or bone-seeking radionuclides (e.g. (90)Sr and (239)Pu). The shortest turnover times for such materials in the whole body were evaluated for the newborn: 11 d and 0.5 y for carbon and calcium, respectively. However, their biokinetic behaviour is complicated by a particularly high percentage of the gut-absorbed dietary intake of carbon (approximately 16%) and calcium (approximately 100%) that is incorporated into the soft tissue and skeleton of the growing neonate. The International Commission on Radiological Protection dose coefficients (Sv Bq(-1)) were examined for 14 radionuclides, including 9 of concern because of their potential use in radiological dispersal devices. The dose coefficients for a 3-month-old are greater than those for adults (2-56 times more for ingestion and 2-12 times for inhalation). The age-dependent dose and exposure assessment of contaminant intakes would improve by accounting for gender and growth where it is currently neglected. Health risk is evaluated as the product of the exposure and hazard factors, the latter being about 10-fold greater in infants than in adults. The exposure factor is also approximately 10-fold higher for ingestion by infants than by adults, and unity for inhalation varying with the contaminant. Qualitative and quantitative physiological and epidemiological evidence supports infants being more vulnerable to cancer and neurological deficit than older children.

  13. Strategies for Transferring Mixtures of Organic Contaminants from Aquatic Environments into Bioassays

    DEFF Research Database (Denmark)

    Jahnke, Annika; Mayer, Philipp; Schäfer, Sabine;

    2016-01-01

    Mixtures of organic contaminants are ubiquitous in the environment. Depending on their persistence and physicochemical properties, individual chemicals that make up the mixture partition and distribute within the environment and might then jointly elicit toxicological effects. For the assessment...

  14. Application of Biologically-Based Lumping To Investigate the Toxicological Interactions of a Complex Gasoline Mixture

    Science.gov (United States)

    People are often exposed to complex mixtures of environmental chemicals such as gasoline, tobacco smoke, water contaminants, or food additives. However, investigators have often considered complex mixtures as one lumped entity. Valuable information can be obtained from these exp...

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

    Science.gov (United States)

    Wotring, Virginia E

    2016-01-01

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

  16. Titan at the time of the Cassini spacecraft first flyby: a prediction for its origin, bulk chemical composition and internal physical structure

    CERN Document Server

    Prentice, A J R

    2006-01-01

    I report the results of a new set of calculations for the gravitational contraction of the proto-solar cloud to quantify the idea that Titan may be a captured moon of Saturn (Prentice 1981, 1984). It is proposed that Titan initially condensed as a secondary embryo in the same proto-solar gas ring from which the central solid core and gaseous envelope of Saturn were acquired. At the orbit of Saturn, the bulk chemical constituents of the condensate are rock (mass fraction 0.494), water ice (0.474), and graphite (0.032). The mean density is 1523 kg/m^3. Structural models for a frozen Titan yield a mean density of 2095 kg/m^3 (chemically homogeneous case) and 1904 kg/m^3 (fully differentiated 2-zone case). The agreement to one percent of the latter value with the observed mean density suggests that Titan is indeed a fully differentiated satellite. The value of C/MR^2 for this model is 0.316. It is predicted that Titan has no internal ocean or induced magnetic field but it may possess a small native dipole field o...

  17. Mixtures Equation Pilot Program to Reduce Animal Testing

    Science.gov (United States)

    EPA is announcing the start of a pilot program to evaluate the usefulness and acceptability of a mathematical tool (the GHS Mixtures Equation), which is used in the Globally Harmonized System of Classification and Labeling of Chemicals (GHS).

  18. Carcinogenicity of individual and a mixture of dioxin-like compounds in female Harlan Sprague Dawley rats

    Energy Technology Data Exchange (ETDEWEB)

    Walker, N.; Nyska, A. [National Institute of Environmental Health Sciences, Research Triangle Park, NC (United States); Crockett, P. [Constella Group, Research Triangle Park, NC (US)] (and others)

    2004-09-15

    The human health risk posed by exposure to persistent organochlorine pollutants (POPs), including polychlorinated-dioxins (PCDDs), -furans (PCDFs) and - biphenyls (PCBs), present in the food and the environment is one of widespread concern throughout the industrialized world. The dioxin Toxic Equivalency Factor (TEF) approach is currently the most feasible interim approach for assessing and managing the risk posed by exposure to mixtures of these compounds and has been formally adopted by regulatory bodies in many countries, the International Programme on Chemical Safety and the World Health Organization. The TEF methodology is a relative potency scheme that estimates the total exposure and biological effects of a mixture of chemicals based on a common mechanism of action involving an initial binding of the compound to the Aryl hydrocarbon receptor (AhR). An implicit assumption of the TEF methodology is that the combined risk of effects of the different congeners is dose additive. Therefore, the total dioxin toxic equivalents (TEQs) of a mixture of PCDDs, PCDFs, and PCBs may be estimated by the summation of the mass of each compound in the mixture after adjustment for its potency relative to that of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). While dose additivity is supported for certain mixtures for some biological endpoints in some experimental models, this has never been evaluated for cancer risk. Here we present a summary of four chronic rodent bioassay conducted by the National Toxicology Program (US Department of Health and Human Services) that evaluated the carcinogenicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 3.3',4,4',5- pentachlorobiphenyl (PCB126) and 2,3,4,7,8 pentachlorodibenzofuran (PeCDF) and a mixture of these three dioxin-like compounds in female Harlan Sprague Dawley rats. Data from these studies will be used to test the hypothesis of dose-additivity of carcinogenicity by a defined mixture of dioxin-like compounds.

  19. Chemical recognition software

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, J.S.; Trahan, M.W.; Nelson, W.E.; Hargis, P.H. Jr.; Tisone, G.C.

    1994-06-01

    We have developed a capability to make real time concentration measurements of individual chemicals in a complex mixture using a multispectral laser remote sensing system. Our chemical recognition and analysis software consists of three parts: (1) a rigorous multivariate analysis package for quantitative concentration and uncertainty estimates, (2) a genetic optimizer which customizes and tailors the multivariate algorithm for a particular application, and (3) an intelligent neural net chemical filter which pre-selects from the chemical database to find the appropriate candidate chemicals for quantitative analyses by the multivariate algorithms, as well as providing a quick-look concentration estimate and consistency check. Detailed simulations using both laboratory fluorescence data and computer synthesized spectra indicate that our software can make accurate concentration estimates from complex multicomponent mixtures, even when the mixture is noisy and contaminated with unknowns.

  20. Chemical recognition software

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, J.S.; Trahan, M.W.; Nelson, W.E.; Hargis, P.J. Jr.; Tisone, G.C.

    1994-12-01

    We have developed a capability to make real time concentration measurements of individual chemicals in a complex mixture using a multispectral laser remote sensing system. Our chemical recognition and analysis software consists of three parts: (1) a rigorous multivariate analysis package for quantitative concentration and uncertainty estimates, (2) a genetic optimizer which customizes and tailors the multivariate algorithm for a particular application, and (3) an intelligent neural net chemical filter which pre-selects from the chemical database to find the appropriate candidate chemicals for quantitative analyses by the multivariate algorithms, as well as providing a quick-look concentration estimate and consistency check. Detailed simulations using both laboratory fluorescence data and computer synthesized spectra indicate that our software can make accurate concentration estimates from complex multicomponent mixtures. even when the mixture is noisy and contaminated with unknowns.

  1. Computer simulation of rod-sphere mixtures

    CERN Document Server

    Antypov, D

    2003-01-01

    Results are presented from a series of simulations undertaken to investigate the effect of adding small spherical particles to a fluid of rods which would otherwise represent a liquid crystalline (LC) substance. Firstly, a bulk mixture of Hard Gaussian Overlap particles with an aspect ratio of 3:1 and hard spheres with diameters equal to the breadth of the rods is simulated at various sphere concentrations. Both mixing-demixing and isotropic-nematic transition are studied using Monte Carlo techniques. Secondly, the effect of adding Lennard-Jones particles to an LC system modelled using the well established Gay-Berne potential is investigated. These rod-sphere mixtures are simulated using both the original set of interaction parameters and a modified version of the rod-sphere potential proposed in this work. The subject of interest is the internal structure of the binary mixture and its dependence on density, temperature, concentration and various parameters characterising the intermolecular interactions. Both...

  2. Efficient radiative transfer in dust grain mixtures

    CERN Document Server

    Wolf, S

    2003-01-01

    The influence of a dust grain mixture consisting of spherical dust grains with different radii and/or chemical composition on the resulting temperature structure and spectral energy distribution of a circumstellar shell is investigated. The comparison with the results based on an approximation of dust grain parameters representing the mean optical properties of the corresponding dust grain mixture reveal that (1) the temperature dispersion of a real dust grain mixture decreases substantially with increasing optical depth, converging towards the temperature distribution resulting from the approximation of mean dust grain parameters, and (2) the resulting spectral energy distributions do not differ by more than 10% if >= 2^5 grain sizes are considered which justifies the mean parameter approximation and the many results obtained under its assumption so far. Nevertheless, the dust grain temperature dispersion at the inner boundary of a dust shell may amount to >>100K and has therefore to be considered in the cor...

  3. IGNITION IMPROVEMENT OF LEAN NATURAL GAS MIXTURES

    Energy Technology Data Exchange (ETDEWEB)

    Jason M. Keith

    2005-02-01

    This report describes work performed during a thirty month project which involves the production of dimethyl ether (DME) on-site for use as an ignition-improving additive in a compression-ignition natural gas engine. A single cylinder spark ignition engine was converted to compression ignition operation. The engine was then fully instrumented with a cylinder pressure transducer, crank shaft position sensor, airflow meter, natural gas mass flow sensor, and an exhaust temperature sensor. Finally, the engine was interfaced with a control system for pilot injection of DME. The engine testing is currently in progress. In addition, a one-pass process to form DME from natural gas was simulated with chemical processing software. Natural gas is reformed to synthesis gas (a mixture of hydrogen and carbon monoxide), converted into methanol, and finally to DME in three steps. Of additional benefit to the internal combustion engine, the offgas from the pilot process can be mixed with the main natural gas charge and is expected to improve engine performance. Furthermore, a one-pass pilot facility was constructed to produce 3.7 liters/hour (0.98 gallons/hour) DME from methanol in order to characterize the effluent DME solution and determine suitability for engine use. Successful production of DME led to an economic estimate of completing a full natural gas-to-DME pilot process. Additional experimental work in constructing a synthesis gas to methanol reactor is in progress. The overall recommendation from this work is that natural gas to DME is not a suitable pathway to improved natural gas engine performance. The major reasons are difficulties in handling DME for pilot injection and the large capital costs associated with DME production from natural gas.

  4. Chemical warfare in freshwater

    NARCIS (Netherlands)

    Mulderij, Gabi

    2006-01-01

    Aquatic macrophytes can excrete chemical substances into their enviroment and these compounds may inhibit the growth of phytoplankton. This process is defined as allelopathy: one organism has effects on another via the excretion of a (mixture of) chemical substance(s). With laboratory and field expe

  5. Occupational exposure to chemical and biological agents in the nonproduction departments of pulp, paper, and paper product mills: an international study.

    Science.gov (United States)

    Teschke, K; Ahrens, W; Andersen, A; Boffetta, P; Fincham, S; Finkelstein, M; Henneberger, P; Kauppinen, T; Kogevinas, M; Korhonen, K; Liss, G; Liukkonnen, T; Osvoll, P; Savela, A; Szadkowska-Stanczyk, I; Westberg, H; Widerkiewicz, K

    1999-01-01

    As part of an international epidemiological study of workers in the pulp and paper industry, previously unpublished exposure measurements were assembled in a database. This article describes 7293 measurements in nonproduction departments from 147 mills in 11 countries. The greatest variety of agents was measured in the maintenance, construction, and cleaning department, where high exposures to asbestos, chromium [VI] compounds, copper, mercury in urine, nitrogen dioxide, ozone, styrene, sulfur dioxide, trichloroethylene, and welding fumes were observed. Measurements in the storage, yard, loading, and shipping department indicated high exposures to asbestos, carbon monoxide, fungal spores, nitrogen oxides, sulfur dioxide, and total dust. The steam and power generation department had high exposures to methyl mercaptan, silica, and total dust. Measurements in process and effluent water treatment, laboratory and research, engineering, and office, administration, and cafeteria areas had few elevated exposures. Throughout the nonproduction departments, measurements of pulp-production chemicals such as chlorine and sulfur compounds tended to be low, with many below detection limits. There were some problems with the available data; in particular, detection limits were often not specified, and the data tended to be clustered in such a way that sources of exposure variability could not be distinguished. Despite these problems, the data provide new insight into the exposures of nonproduction pulp and paper industry personnel.

  6. Analytical processing of binary mixture information by olfactory bulb glomeruli.

    Directory of Open Access Journals (Sweden)

    Max L Fletcher

    Full Text Available Odors are rarely composed of a single compound, but rather contain a large and complex variety of chemical components. Often, these mixtures are perceived as having unique qualities that can be quite different than the combination of their components. In many cases, a majority of the components of a mixture cannot be individually identified. This synthetic processing of odor information suggests that individual component representations of the mixture must interact somewhere along the olfactory pathway. The anatomical nature of sensory neuron input into segregated glomeruli with the bulb suggests that initial input of odor information into the bulb is analytic. However, a large network of interneurons within the olfactory bulb could allow for mixture interactions via mechanisms such as lateral inhibition. Currently in mammals, it is unclear if postsynaptic mitral/tufted cell glomerular mixture responses reflect the analytical mixture input, or provide the initial basis for synthetic processing with the olfactory system. To address this, olfactory bulb glomerular binary mixture representations were compared to representations of each component using transgenic mice expressing the calcium indicator G-CaMP2 in olfactory bulb mitral/tufted cells. Overall, dorsal surface mixture representations showed little mixture interaction and often appeared as a simple combination of the component representations. Based on this, it is concluded that dorsal surface glomerular mixture representations remain largely analytical with nearly all component information preserved.

  7. Chemical Characterization and Toxicologic Evaluation of Airborne Mixtures. Tumorigenicity Studies of Diesel Fuel-2, Red Smoke Dye and Violet Smoke Dyes in the SENCAR Mouse Skin Tumorigenesis Bioassay System

    Science.gov (United States)

    1985-09-01

    nitrosamides, sulfonates, sultones, and ureas. The 32 chemicals listed in Table 1 include such well known chemical carcino- gens as aflatoxin BI, bis...direct or indirect carcinogen at a subthreshold dose and is essentially irreversible. The promotion phase requires repetitive treatments after...34by initiators of mouse skin tumorigenesis. Cancer Res. 29: 510-514. Hennings, H., B. Michael, and E. Patterson. 1978. Croton oil enhancement of skin

  8. Bioaccessibility assessment of patulin and ochratoxin A in cereal and fruit based baby foods using a harmonized in vitro digestion model: contribution for the risk assessment of chemical mixtures

    OpenAIRE

    Assunção, R.; Martins, C.; Leclerc Duarte, E.; Alvito, P.

    2015-01-01

    People, animals and the environment can be exposed to multiple chemicals at once from a variety of sources, but current risk assessment is usually carried out on one chemical substance at a time. Mycotoxins are fungal natural contaminants commonly found in a variety of foods including baby foods and have been found in cereal and fruit based baby foods. In human health risk assessment, ingestion of food is considered a major route of exposure to many contaminants including mycotoxins, although...

  9. Estimation of the acute inhalation hazards of chemicals based on route-to-route and local endpoint extrapolation: Experience from Bulk Maritime Transport

    NARCIS (Netherlands)

    Höfer, T.; James, D.; Syversen, T.; Bowmer, T.

    2011-01-01

    Data on acute lethal inhalation toxicity from animal studies are commonly required for assessing the hazards to human health of volatile, gaseous and dusty chemicals or their mixtures. The International Maritime Organisation (IMO) made the provision of acute inhalation toxicity data a mandatory requ

  10. Tandem mass spectrometry: analysis of complex mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Singleton, K.E.

    1985-01-01

    Applications of tandem mass spectrometry (MS/MS) for the analysis of complex mixtures results in increased specificity and selectivity by using a variety of reagent gases in both negative and positive ion modes. Natural isotopic abundance ratios were examined in both simple and complex mixtures using parent, daughter and neutral loss scans. MS/MS was also used to discover new compounds. Daughter scans were used to identify seven new alkaloids in a cactus species. Three of these alkaloids were novel compounds, and included the first simple, fully aromatic isoquinoline alkaloids reported in Cactaceae. MS/MS was used to characterize the chemical reaction products of coal in studies designed to probe its macromolecular structure. Negative ion chemical ionization was utilized to study reaction products resulting from the oxidation of coal. Possible structural units in the precursor coal were predicted based on the reaction products identified, aliphatic and aromatic acids and their anhydrides. The MS/MS method was also used to characterize reaction products resulting from coal liquefaction and/or extraction. These studies illustrate the types of problems for which MS/MS is useful. Emphasis has been placed on characterization of complex mixtures by selecting experimental parameters which enhance the information obtained. The value of using MS/MS in conjunction with other analytical techniques as well as the chemical pretreatment is demonstrated.

  11. Pointer Sentinel Mixture Models

    OpenAIRE

    Merity, Stephen; Xiong, Caiming; Bradbury, James; Socher, Richard

    2016-01-01

    Recent neural network sequence models with softmax classifiers have achieved their best language modeling performance only with very large hidden states and large vocabularies. Even then they struggle to predict rare or unseen words even if the context makes the prediction unambiguous. We introduce the pointer sentinel mixture architecture for neural sequence models which has the ability to either reproduce a word from the recent context or produce a word from a standard softmax classifier. O...

  12. Phase diagrams for an ideal gas mixture of fermionic atoms and bosonic molecules

    DEFF Research Database (Denmark)

    Williams, J. E.; Nygaard, Nicolai; Clark, C. W.

    2004-01-01

    We calculate the phase diagrams for a harmonically trapped ideal gas mixture of fermionic atoms and bosonic molecules in chemical and thermal equilibrium, where the internal energy of the molecules can be adjusted relative to that of the atoms by use of a tunable Feshbach resonance. We plot...... the molecule fraction and the fraction of Bose-condensed molecules as functions of the temperature and internal molecular energy. We show the paths traversed in the phase diagrams when the molecular energy is varied either suddenly or adiabatically. Our model calculation helps to interpret the adiabatic phase...... diagrams obtained in recent experiments on the Bose-Einstein condensation to Bardeen-Cooper-Schrieffer crossover, in which the condensate fraction is plotted as a function of the initial temperature of the Fermi gas measured before a sweep of the magnetic field through the resonance region....

  13. Lifetime of the internal reference oxygen sensor

    DEFF Research Database (Denmark)

    Hu, Qiang; Jacobsen, Torben; Hansen, Karin Vels;

    2013-01-01

    The internal reference oxygen sensor (IROS) based on a binary mixture of metal and its stoichiometric oxide is subject to leaks that result in consumption of the binary mixture. An IROS loses the functionality when the binary mixture is exhausted. Among the possible leak sources the electronic leak...

  14. Report on survey of international cooperation possibility on chemical CO2 fixation and utilization technology in FY 1997; 1997 nendo chosa hokokusho (kagakuteki CO2 koteika yuko riyo gijutsu ni kakawaru kokusai kyoryoku kanosei chosa)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    This survey focused on the end of the more promising companion and promoting the international cooperation on chemical CO2 fixation and utilization technology. As a result, the way of the carrying-forward of the international cooperation with more than one companion could be arranged beforehand. It led to getting an arrangement about a secrecy agreement respectively with Lurgi company and ABB company in Europe, and to providing a catalyst sample developed by RITE to implement an examination by the other party and to show related technical information. In addition, it concluded a cooperation agreement about a total system of the chemical CO2 fixation and utilization technology and methanol synthesis with ZSW. In Australia, negotiation about international cooperation with CSIRO which is a federal research organization and CRC (Cooperative Research Centre) for renewable energy has been started. The ideal circumstances are being ready for the chemical CO2 fixation project for which the international cooperation with the country where the natural energy is rich like Australia is essential when coming to practical use. To do alternating current with further high density in the following year it is desired to build a concrete study cooperation system. 1 fig., 4 tabs.

  15. Feasibility study of international cooperation on the chemical CO2 fixation and effective utilization technology in FY 1996; 1996 nendo kagakuteki CO2 koteika yuko riyo gijutsu ni kakawaru kokusai kyoryoku kanosei chosa

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-03-01

    In this survey, candidate organizations to cooperate internationally in the development of chemical CO2 fixation technologies have been selected, and possible forms of the cooperation each organization would participate in have been examined. The chemical CO2 fixation technology project of RITE (Research Institute of Innovation Technology for the Earth) involves the essential themes of CO2 separation membrane technology, catalytic hydrogenation reaction technology, and hydrogen production/supply technology, as well as the overall system. Through the arrangement, 19 international research institutes were selected as the potential candidates for international research cooperation. Either direct visit or questionnaire by mail was conducted to these institutes. The purposes of international cooperation in each of essential study theme are to review the possibility of improving technologies in each theme by introducing new technologies, and to review the possibilities of promoting practical implementation of chemical CO2 fixation system. The research institutes to be reviewed as partners for joint research are summarized. 10 figs., 16 tabs.

  16. Análisis Químico de Mezclas Biodiesel de Aceite de Cocina Usado y Diesel por Espectroscopia Infrarroja Chemical Analysis of Mixtures of Biodiesel from Used Cooking Oil and Diesel by Infrared Spectroscopy

    Directory of Open Access Journals (Sweden)

    Jennifer J Lafont

    2011-01-01

    Full Text Available Se propone un método eficiente para determinar los porcentajes óptimos de mezclas biodiesel de aceite usado y diesel, para uso automotor. El procedimiento consiste en recolección del aceite usado, limpieza de residuos, y obtención del biodiesel mediante una reacción de transesterificación, con diferentes proporciones molares metanol/aceite . Las muestras fueron analizadas por espectroscopia infrarroja. Se encontró que una proporción metanol/aceite de 1:8 presentó mayor rendimiento en la obtención de biodiesel. Los espectros de infrarrojo mostraron el incremento del máximo de carbonilo de los esteres metílicos al aumentar las concentraciones de biodiesel en las mezcla biodiesel+diesel. Se concluye que la técnica usada cumple con la ley de Beer-Lambert y es adecuada para cuantificar este tipo de mezclas.An efficient method to determine the optimum percentages of blends biodiesel from used oil and diesel for automotive use, is proposed. The procedure consists of recollection of used frying oil, residue cleaning and synthesis of biodiesel by a transesterification reaction with different molar proportions of methanol/oil. The samples were analyzed by infrared spectroscopy. It was found that a ratio methanol/oil of 1:8 showed higher performance in the production of biodiesel. The infrared spectra showed an increase in the carbonyl peak of the methyl esters with the increase of the concentration of biodiesel in the mixtures biodiesel+diesel. It is concluded that proposed technique complies with the Beer-Lambert law and it is a good method to quantify these types of mixtures.

  17. Essays on Finite Mixture Models

    NARCIS (Netherlands)

    A. van Dijk (Bram)

    2009-01-01

    textabstractFinite mixture distributions are a weighted average of a ¯nite number of distributions. The latter are usually called the mixture components. The weights are usually described by a multinomial distribution and are sometimes called mixing proportions. The mixture components may be the sam

  18. Mixtures of truncated basis functions

    DEFF Research Database (Denmark)

    Langseth, Helge; Nielsen, Thomas Dyhre; Rumí, Rafael

    2012-01-01

    In this paper we propose a framework, called mixtures of truncated basis functions (MoTBFs), for representing general hybrid Bayesian networks. The proposed framework generalizes both the mixture of truncated exponentials (MTEs) framework and the mixture of polynomials (MoPs) framework. Similar...

  19. Separating Underdetermined Convolutive Speech Mixtures

    DEFF Research Database (Denmark)

    Pedersen, Michael Syskind; Wang, DeLiang; Larsen, Jan

    2006-01-01

    a method for underdetermined blind source separation of convolutive mixtures. The proposed framework is applicable for separation of instantaneous as well as convolutive speech mixtures. It is possible to iteratively extract each speech signal from the mixture by combining blind source separation...

  20. Combustion of soybean oil and diesel mixtures for heating purposes

    Energy Technology Data Exchange (ETDEWEB)

    Guimaraes, Adriana Correa; Sanz, Jose Francisco [European University Miguel de Cervantes, Valladolid (Spain)], E-mail: acorrea@uemc.es; Hernandez, Salvador; Navas, Luis Manuel; Rodriguez, Elena; Ruiz, Gonzalo [University of Valladolid (Spain). Dept. of Agricultural and Forest Engineering; San Jose, Julio [University of Valladolid (Spain). Dept. of Energetic Engineering; Gomez, Jaime [University of Valladolid (Spain). Dept. of Communications and Signal Theory and Telematics Engineering

    2008-07-01

    Using blends of vegetable oils with petroleum derivates for heating purposes has several advantages over other energy application for vegetable oils. This paper presents the results of an investigation by use of soybean oil and diesel mixture as fuel for producing heat in conventional diesel installation. The paper is set out as follows: properties characterization of soybean oil as fuel and of diesel oil, as well as the mixture of both; selection of the mixture according to their physical chemical properties and how they adapt to conventional combustion installation; experimentation with the selected mixture, allowing the main combustion parameters to be measured; processing the collected data, values of combustion, efficiency and reduction of emissions. Conclusions show that the use of soybean oil and diesel mixture for producing heat energy in conventional equipment is feasible and beneficial for reduction emissions. (author)

  1. Cementitious barriers partnership concrete mixture characterization

    Energy Technology Data Exchange (ETDEWEB)

    Langton, C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Protiere, Yannick [SIMCO Technologies, Inc., Quebec (Canada)

    2014-12-01

    This report summarizes the characterization study performed on two concrete mixtures used for radioactive waste storage. Both mixtures were prepared with approximately 425 kg of binder. The testing protocol mostly focused on determining the transport properties of the mixtures; volume of permeable voids (porosity), diffusion coefficients, and water permeability were evaluated. Tests were performed after different curing durations. In order to obtain data on the statistical distribution of transport properties, the measurements after 2 years of curing were performed on 10+ samples. Overall, both mixtures exhibited very low tortuosities and permeabilities, a direct consequence of their low water-to-binder ratio and the use of supplementary cementitious materials. The data generated on 2-year old samples showed that porosity, tortuosity and permeability follow a normal distribution. Chloride ponding tests were also performed on test samples. They showed limited chloride ingress, in line with measured transport properties. These test results also showed that both materials react differently with chloride, a consequence of the differences in the binder chemical compositions.

  2. Concrete mixture characterization. Cementitious barriers partnership

    Energy Technology Data Exchange (ETDEWEB)

    Langton, C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Protiere, Yannick [SIMCO Technologies, Inc., Quebec (Canada)

    2014-12-01

    This report summarizes the characterization study performed on two concrete mixtures used for radioactive waste storage. Both mixtures were prepared with approximately 425 kg of binder. The testing protocol mostly focused on determining the transport properties of the mixtures; volume of permeable voids (porosity), diffusion coefficients, and water permeability were evaluated. Tests were performed after different curing durations. In order to obtain data on the statistical distribution of transport properties, the measurements after 2 years of curing were performed on 10+ samples. Overall, both mixtures exhibited very low tortuosities and permeabilities, a direct consequence of their low water-to-binder ratio and the use of supplementary cementitious materials. The data generated on 2-year old samples showed that porosity, tortuosity and permeability follow a normal distribution. Chloride ponding tests were also performed on test samples. They showed limited chloride ingress, in line with measured transport properties. These test results also showed that both materials react differently with chloride, a consequence of the differences in the binder chemical compositions.

  3. Chemical reaction and separation method

    NARCIS (Netherlands)

    Jansen, J.C.; Kapteijn, F.; Strous, S.A.

    2005-01-01

    The invention is directed to process for performing a chemical reaction in a reaction mixture, which reaction produces water as by-product, wherein the reaction mixture is in contact with a hydroxy sodalite membrane, through which water produced during the reaction is removed from the reaction mixtu

  4. Study on the Synthesis of Chemical Intermediate from the Mixture of o-Cresol, m-Cresol and p-Cresol%混合邻间对甲酚制备化工中间体的工艺研究

    Institute of Scientific and Technical Information of China (English)

    吴鸿宾

    2014-01-01

    以介孔分子筛为催化剂,催化烷基化混合邻间对甲酚制备6-叔丁基邻甲酚、6-叔丁基间甲酚、2-叔丁基对甲酚混合液,并精馏获得三种叔丁基甲酚纯品。考查了催化剂用量、异丁烯用量、反应温度等反应条件对烷基化反应的影响,确定了最佳工艺条件。结果表明,催化剂为三混甲酚用量的2.0%(质量),异丁烯用量与三混甲酚用量之比为1.05∶1(摩尔比),最佳反应温度为95℃的反应条件下,三混甲酚的总转化率达到96.25%以上,反应液中目标产品含量达94.67%,产品选择性可达98.36%。精馏后,6-叔丁基邻甲酚、6-叔丁基间甲酚、2-叔丁基对甲酚三种产品的质量含量分别为99.75%、99.57%、99.54%。整个工艺过程安全环保,成本低,能耗低,收益高。%The alkylation reaction of mixture of o-cresol,m-cresol and p-cresol catalyzed by mesoporous molecular sieve catalyst to 2-tert-butyl-o-cresol,6-tert-butyl-m-cresol and 2-tert-butyl-p-cresol was studied. The effects of reaction conditions,namely catalyst dosage,isobutene dosage and reaction temperature were investigated. The reaction conditions were determined. The experimental results showed that the conversion could reach 96.25%, the selectivity could reach 98.36 % under the reaction conditions of reaction: catalyst/the cresol mixture weight ratio of 2%, temperature 95℃. The process is safe and environmentally friendly with low cost and low energy consumption.

  5. Mixture Based Outlier Filtration

    Directory of Open Access Journals (Sweden)

    P. Pecherková

    2006-01-01

    Full Text Available Success/failure of adaptive control algorithms – especially those designed using the Linear Quadratic Gaussian criterion – depends on the quality of the process data used for model identification. One of the most harmful types of process data corruptions are outliers, i.e. ‘wrong data’ lying far away from the range of real data. The presence of outliers in the data negatively affects an estimation of the dynamics of the system. This effect is magnified when the outliers are grouped into blocks. In this paper, we propose an algorithm for outlier detection and removal. It is based on modelling the corrupted data by a two-component probabilistic mixture. The first component of the mixture models uncorrupted process data, while the second models outliers. When the outlier component is detected to be active, a prediction from the uncorrupted data component is computed and used as a reconstruction of the observed data. The resulting reconstruction filter is compared to standard methods on simulated and real data. The filter exhibits excellent properties, especially in the case of blocks of outliers. 

  6. RANS analyses on erosion behavior of density stratification consisted of helium–air mixture gas by a low momentum vertical buoyant jet in the PANDA test facility, the third international benchmark exercise (IBE-3)

    Energy Technology Data Exchange (ETDEWEB)

    Abe, Satoshi, E-mail: abe.satoshi@jaea.go.jp; Ishigaki, Masahiro; Sibamoto, Yasuteru; Yonomoto, Taisuke

    2015-08-15

    Highlights: . • The third international benchmark exercise (IBE-3) focused on density stratification erosion by a vertical buoyant jet in the reactor containment vessel. • Two types turbulence model modification were applied in order to accurately simulate the turbulence helium transportation in the density stratification. • The analysis result in case with turbulence model modification is good agreement with the experimental data. • There is a major difference of turbulence helium–mass transportation between in case with and without the turbulence model modification. - Abstract: Density stratification in the reactor containment vessel is an important phenomenon on an issue of hydrogen safety. The Japan Atomic Energy Agency (JAEA) has started the ROSA-SA project on containment thermal hydraulics. As a part of the activity, we participated in the third international CFD benchmark exercise (IBE-3) focused on density stratification erosion by a vertical buoyant jet in containment vessel. This paper shows our approach for the IBE-3, focusing on the turbulence transport phenomena in eroding the density stratification and introducing modified turbulence models for improvement of the CFD analyses. For this analysis, we modified the CFD code OpenFOAM by using two turbulence models; the Kato and Launder modification to estimate turbulent kinetic energy production around a stagnation point, and the Katsuki model to consider turbulence damping in density stratification. As a result, the modified code predicted well the experimental data. The importance of turbulence transport modeling is also discussed using the calculation results.

  7. Physical and chemical properties of binary mixture of N-butylpyridinium nitrate and alcohol%吡啶硝酸盐与醇二元混合体系物化性能研究

    Institute of Scientific and Technical Information of China (English)

    王建英; 梁丽亚; 昝昊搏; 胡永琪

    2012-01-01

    In this paper, MDY-2 electronic densitometer and Germany DCAT21 automatic surface tension meter are used to measure the density and surface tension over the whole concentration range (the molar fraction of ionic liquids in oganic solvents is 0~l) for the binary mixtures of ionic liquids N-butylpyridinium nitrate ([BuPy]NO3) and organic solvents such as metha-nol,ethanol and butanol at the temperature of 298. 15 K. The excess molar volumes VE and the surface tension deviations δγ of binary mixtures {[BuPy]NO3+CH3OH},{[BuPy]NO3+C2H5OH} and {[BuPy]NO3+C4H9OH} are determined. VE and δγ are fitted by using the Redlich-Kister equation. The results show that the excess molar volumes of binary mixtures of {[BuPy]NO3+CH3OH} and {[BuPy]NO3+C2H5()H} are negative over the whole composition range, while the VE of binary mixture {[BuPy]NO3 +C, H9OH} has positive values at low molar fraction of ionic liquid, passing through a maximum and then decreases and becomes negative, showing minimum at higher ionic liquid molar fractioa The surface tension deviations δr of {[BuPy]NO3 +CH3OH} systems are positive, but those of {[BuPy]NO3 +Cz H5OH} and {[BuPy]NO3 +G, H9OH} systems are negative over the entire molar fraction range. It seems that surface tension deviations δγ varys from positive to negative with the increase of alkyl chain length of alcohols.%采用MDY-2电子密度仪和德国DCAT21全自动表面张力仪,在298.15 K下测定了离子液体N-丁基吡啶硝酸盐(N-butylpyridinium nitrate,[BuPy]NO3)与有机溶剂甲醇、乙醇、正丁醇在全浓度范围内(离子液体在有机溶剂中的摩尔分数为0~1)的密度和表面张力,计算了二元体系{[BuPy]NO3+CH3OH},{[BuPy]NO3 +C2H5OH}和{[BuPy] NO3+C4H9OH}的超额摩尔体积VE和表面张力偏差δγ,分别利用Redlich-Kister方程对二元体系的超额摩尔体积VE和表面张力偏差δγ进行了拟合.结果表明:二元体系{[BuPy] NO3 +CH3 OH}和{[BuPy] NO3 +C2 H5 OH}的超额摩尔体积VE

  8. Microwaves in chemistry: Another way of heating reaction mixtures

    Science.gov (United States)

    Berlan, J.

    1995-04-01

    The question of a possible "microwave activation" of chemical reaction is discussed. In fact two cases should be distinguished: homogeneous or heterogeneous reaction mixtures. In homogeneous mixtures there are no (or very low) rate enhancements compared to a conventional heating, but some influence on chemioselectivity has been observed. These effects derive from fast and mass heating of microwaves, and probably, especially under reflux, from different boiling rates and/or overheating. With heterogeneous mixtures non conventional effects probably derive from mass heating and selective overheating. This is illustrated with several reactions: Diels-Alder, naphthalene sulphonation, preparation of cyanuric acid, hydrolysis of nitriles, transposition reaction on solid support.

  9. Novel mixture model for the representation of potential energy surfaces

    Science.gov (United States)

    Pham, Tien Lam; Kino, Hiori; Terakura, Kiyoyuki; Miyake, Takashi; Dam, Hieu Chi

    2016-10-01

    We demonstrate that knowledge of chemical physics on a materials system can be automatically extracted from first-principles calculations using a data mining technique; this information can then be utilized to construct a simple empirical atomic potential model. By using unsupervised learning of the generative Gaussian mixture model, physically meaningful patterns of atomic local chemical environments can be detected automatically. Based on the obtained information regarding these atomic patterns, we propose a chemical-structure-dependent linear mixture model for estimating the atomic potential energy. Our experiments show that the proposed mixture model significantly improves the accuracy of the prediction of the potential energy surface for complex systems that possess a large diversity in their local structures.

  10. Modeling and interpreting biological effects of mixtures in the environment: introduction to the metal mixture modeling evaluation project.

    Science.gov (United States)

    Van Genderen, Eric; Adams, William; Dwyer, Robert; Garman, Emily; Gorsuch, Joseph

    2015-04-01

    The fate and biological effects of chemical mixtures in the environment are receiving increased attention from the scientific and regulatory communities. Understanding the behavior and toxicity of metal mixtures poses unique challenges for incorporating metal-specific concepts and approaches, such as bioavailability and metal speciation, in multiple-metal exposures. To avoid the use of oversimplified approaches to assess the toxicity of metal mixtures, a collaborative 2-yr research project and multistakeholder group workshop were conducted to examine and evaluate available higher-tiered chemical speciation-based metal mixtures modeling approaches. The Metal Mixture Modeling Evaluation project and workshop achieved 3 important objectives related to modeling and interpretation of biological effects of metal mixtures: 1) bioavailability models calibrated for single-metal exposures can be integrated to assess mixture scenarios; 2) the available modeling approaches perform consistently well for various metal combinations, organisms, and endpoints; and 3) several technical advancements have been identified that should be incorporated into speciation models and environmental risk assessments for metals.

  11. Partitioning regularity of non-ionic organic mixtures in organic phase/water system

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The partitioning regularity of nonionic organic mixtures in organic phase/water system is revealed. The equation for calculating the partition coefficients of mixtures (KMD), together with the determination model, is derived from the equilibrium partitioning models (EPMs). Based on these derived equations, the KMD values of 20 mixtures conraining halogenated benzenes are obtained. The results show that stronger hydrophobicity of an individual chemical in the mixture results in the stronger hydrophobicity of the mixture and the greater the proportion of this chemical, the stronger the hydrophobicity of the mixture will be. This partitioning regularity is helpful to the study of the toxicity for mixtures and the environmental behavior, such as transfer or accumuiation, for mixed organic pollutants.``

  12. Protein mixtures: interactions and gelation

    OpenAIRE

    Ersch, C.

    2015-01-01

    Gelation is a ubiquitous process in the preparation of foods. As most foods are multi constituent mixtures, understanding gelation in mixtures is an important goal in food science. Here we presented a systematic investigation on the influence of molecular interactions on the gelation in protein mixtures. Gelatin gels with added globular protein and globular protein gels with added gelatin were analyzed for their gel microstructure and rheological properties. Mixed gels with altered microstruc...

  13. Dynamics of gas bubble growth in oil-refrigerant mixtures under isothermal decompression

    Energy Technology Data Exchange (ETDEWEB)

    Dias, Joao Paulo; Barbosa Junior, Jader R.; Prata, Alvaro T. [Federal University of Santa Catarina (UFSC), Florianopolis, SC (Brazil). Dept. of Mechanical Engineering], Emails: jpdias@polo.ufsc.br, jrb@polo.ufsc.br, prata@polo.ufsc.br

    2010-07-01

    This paper proposes a numerical model to predict the growth of gaseous refrigerant bubbles in oil-refrigerant mixtures with high contents of oil subjected to isothermal decompression. The model considers an Elementary Cell (EC) in which a spherical bubble is surrounded by a concentric and spherical liquid layer containing a limited amount of dissolved liquid refrigerant. The pressure reduction in the EC generates a concentration gradient at the bubble interface and the refrigerant is transported to the bubble by molecular diffusion. After a sufficiently long period of time, the concentration gradient in the liquid layer and the bubble internal pressure reach equilibrium and the bubble stops growing, having attained its stable radius. The equations of momentum and chemical species conservation for the liquid layer, and the mass balance at the bubble interface are solved via a coupled finite difference procedure to determine the bubble internal pressure, the refrigerant radial concentration distribution and the bubble growth rate. Numerical results obtained for a mixture of ISO VG10 ester oil and refrigerant HFC-134a showed that bubble growth dynamics depends on model parameters like the initial bubble radius, initial refrigerant concentration in the liquid layer, decompression rate and EC temperature. Despite its simplicity, the model showed to be a potential tool to predict bubble growth and foaming which may result from important phenomena occurring inside refrigeration compressors such as lubrication of sliding parts and refrigerant degassing from the oil stored in oil sump during compressor start-up. (author)

  14. Caracterização químico-nutricional de um isolado protéico de soro de leite, um hidrolisado de colágeno bovino e misturas dos dois produtos Chemical-nutritional characterization of a whey protein isolate, a bovine collagen hydrolysate and mixtures of the two products

    Directory of Open Access Journals (Sweden)

    Fabiane La Flor Ziegler

    2009-02-01

    Full Text Available OBJETIVO:Estudar química e nutricionalmente um isolado protéico de soro de leite bovino, um hidrolisado de colágeno bovino e misturas dos dois produtos visando elevado valor nutritivo e funcional. MÉTODOS: Realizaram-se análises da composição centesimal e do perfil de aminoácidos dos dois materiais protéicos, para cálculo da melhor adequação dos aminoácidos essenciais, com base no perfil recomendado pela Organização Mundial de Saúde. Os índices de valor nutritivo para o isolado de soro de leite, o hidrolisado de colágeno e as misturas foram determinados em ratos, a partir de ensaios de crescimento e de balanço de nitrogênio. Os resultados dos parâmetros nutricionais foram submetidos à análise de variância e ao teste de Tukey para a verificação de diferenças entre médias (pOBJECTIVE:The objective was the chemical and nutritional study of a bovine whey protein isolate, a bovine collagen hydrolysate and mixtures of the two products aiming at high nutritional and functional value. METHODS: Centesimal composition and amino acid analyses were performed on both proteinaceous materials for the calculation of an adequate amino acid profile based on the Food and Agriculture Organization/World Health Organization recommendation. The nutritive value indexes for the whey protein isolate, the collagen hydrolysate and mixtures of both proteins were determined in rats through growth assay and nitrogen balance. The experimental parameters from nutritional assays were submitted to analysis of variance and the Tukey test applied for differences among means (p<0.05. RESULTS: The whey protein isolate met all the requirements of the Food and Agriculture Organization/World Health Organization reference for essential amino acids while the collagen hydrolysate showed deficiency in all essential amino acids and complete absence of tryptophan. The casein showed higher efficiency than the whey isolate and mixtures of both proteins in promoting

  15. Spectrometric mixture analysis: An unexpected wrinkle

    Indian Academy of Sciences (India)

    Robert De Levie

    2009-09-01

    The spectrometric analysis of a mixture of two chemically and spectroscopically similar compounds is illustrated for the simultaneous spectrometric determination of caffeine and theobromine, the primary stimulants in coffee and tea, based on their ultraviolet absorbances. Their analysis indicates that such measurements may need an unexpectedly high precision to yield accurate answers, because of an artifact of inverse cancellation, in which a small noise or drift signal is misinterpreted in terms of a concentration difference. The computed sum of the concentrations is not affected.

  16. Fundamental combustion characteristics of lean hydrogen mixtures; Suiso kihaku kongoki no kisoteki nensho tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Barat, D.; Kido, H.; Nakahara, M.; Hashimoto, J. [Kyushu University, Fukuoka (Japan)

    1997-10-01

    One of the excellent combustion characteristics of hydrogen-air mixture is that its emission is free of CO2, but the problem of NOx remains, mainly caused by the high combustion temperature. Using leaner mixture and carrying out EGR are supposed to be effective methods to reduce NOx. In this study, to examine the effectiveness of the two methods, fundamental combustion characteristics of nitrogen added lean hydrogen mixtures were investigated by chemical equilibrium calculations and measurements of turbulent combustion characteristics. It is suggested that nitrogen added mixtures can achieve lower NOx combustion than lean mixtures, taking the combustion efficiency into consideration. 7 refs., 7 figs., 1 tab.

  17. 化学工业发展与化工过程强化的内在关系分析%Development of Chemical Industry and Chemical Process Intensification of Internal Relation

    Institute of Scientific and Technical Information of China (English)

    肖素光

    2013-01-01

    In recent years, with the in-depth study of chemistry, chemical industry has been rapid development of fast. Chemical industry in today's society applications continue to increase, is the development of future society mainstream industry. Industry development in addition to technical theory support, the production process is also very important. However, with the current environmental protection and energy saving of the mainstream of the world, the development of chemical industry still faces a challenge. The intensification of chemical engineering process, to a certain extent in the solution of chemical industry of high pollution, high energy consumption, high material consumption and abuse. Therefore, for the development of chemical industry, chemical process intensification will play a very big role in promoting. This article will focus on development of chemical industry and chemical strengthening inner relationship.%近年来,随着化学研究的不断深入,化学工业得以快速迅猛的发展。化学工业在当今社会应用领域不断加大,是未来社会发展的主流工业。行业发展除了需要技术理论的支持,对于其生产加工过程也是非常重要的。但是,伴随着当前环保节能的世界主流,化学工业发展还是面临着一定的挑战。化工过程强化,能够在一定程度上解决化学工业中高污染、高能耗以及高物耗等弊端。因此,对于化学工业发展而言,化工过程强化必然会起到非常大的推动作用。文章就将重点谈论化学工业发展与化工强化的内在关系。

  18. Evaporating Drops of Alkane Mixtures

    CERN Document Server

    Gu'ena, G; Poulard, C; Cazabat, Anne-Marie; Gu\\'{e}na, Geoffroy; Poulard, Christophe

    2005-01-01

    Alkane mixtures are model systems where the influence of surface tension gradients during the spreading and the evaporation of wetting drops can be easily studied. The surface tension gradients are mainly induced by concentration gradients, mass diffusion being a stabilising process. Depending on the relative concentration of the mixture, a rich pattern of behaviours is obtained.

  19. Thermophysical Properties of Hydrocarbon Mixtures

    Science.gov (United States)

    SRD 4 NIST Thermophysical Properties of Hydrocarbon Mixtures (PC database for purchase)   Interactive computer program for predicting thermodynamic and transport properties of pure fluids and fluid mixtures containing up to 20 components. The components are selected from a database of 196 components, mostly hydrocarbons.

  20. Evaporating Drops of Alkane Mixtures

    OpenAIRE

    Guéna, Geoffroy; Poulard, Christophe; Cazabat, Anne-Marie

    2005-01-01

    22 pages 9 figures; Alkane mixtures are model systems where the influence of surface tension gradients during the spreading and the evaporation of wetting drops can be easily studied. The surface tension gradients are mainly induced by concentration gradients, mass diffusion being a stabilising process. Depending on the relative concentration of the mixture, a rich pattern of behaviours is obtained.

  1. Protein mixtures: interactions and gelation

    NARCIS (Netherlands)

    Ersch, C.

    2015-01-01

    Gelation is a ubiquitous process in the preparation of foods. As most foods are multi constituent mixtures, understanding gelation in mixtures is an important goal in food science. Here we presented a systematic investigation on the influence of molecular interactions on the gelation in protein mixt

  2. Easy and flexible mixture distributions

    DEFF Research Database (Denmark)

    Fosgerau, Mogens; Mabit, Stefan L.

    2013-01-01

    We propose a method to generate flexible mixture distributions that are useful for estimating models such as the mixed logit model using simulation. The method is easy to implement, yet it can approximate essentially any mixture distribution. We test it with good results in a simulation study...

  3. EDCs Mixtures: A Stealthy Hazard for Human Health?

    Directory of Open Access Journals (Sweden)

    Edna Ribeiro

    2017-02-01

    Full Text Available Endocrine disrupting chemicals (EDCs are exogenous chemicals that may occur naturally (e.g., phytoestrogens, while others are industrial substances and plasticizers commonly utilized worldwide to which human exposure, particularly at low-doses, is omnipresent, persistent and occurs in complex mixtures. EDCs can interfere with/or mimic estrogenic hormones and, consequently, can simultaneously trigger diverse signaling pathways which result in diverse and divergent biological responses. Additionally, EDCs can also bioaccumulate in lipid compartments of the organism forming a mixed “body burden” of contaminants. Although the independent action of chemicals has been considered the main principle in EDCs mixture toxicity, recent studies have demonstrated that numerous effects cannot be predicted when analyzing single compounds independently. Co-exposure to these agents, particularly in critical windows of exposure, may induce hazardous health effects potentially associated with a complex “body burden” of different origins. Here, we performed an exhaustive review of the available literature regarding EDCs mixtures exposure, toxicity mechanisms and effects, particularly at the most vulnerable human life stages. Although the assessment of potential risks to human health due to exposure to EDCs mixtures is a major topic for consumer safety, information regarding effective mixtures effects is still scarce.

  4. Statistical mechanical theory of fluid mixtures

    Science.gov (United States)

    Zhao, Yueqiang; Wu, Zhengming; Liu, Weiwei

    2014-01-01

    A general statistical mechanical theory of fluid mixtures (liquid mixtures and gas mixtures) is developed based on the statistical mechanical expression of chemical potential of components in the grand canonical ensemble, which gives some new relationships between thermodynamic quantities (equilibrium ratio Ki, separation factor α and activity coefficient γi) and ensemble average potential energy u for one molecule. The statistical mechanical expressions of separation factor α and activity coefficient γi derived in this work make the fluid phase equilibrium calculations can be performed by molecular simulation simply and efficiently, or by the statistical thermodynamic approach (based on the saturated-vapor pressure of pure substance) that does not need microscopic intermolecular pair potential functions. The physical meaning of activity coefficient γi in the liquid phase is discussed in detail from a viewpoint of molecular thermodynamics. The calculated Vapor-Liquid Equilibrium (VLE) properties of argon-methane, methanol-water and n-hexane-benzene systems by this model fit well with experimental data in references, which indicates that this model is accurate and reliable in the prediction of VLE properties for small, large and strongly associating molecules; furthermore the statistical mechanical expressions of separation factor α and activity coefficient γi have good compatibility with classical thermodynamic equations and quantum mechanical COSMO-SAC approach.

  5. Determinação das composições físico-químicas de cachaças do sul de minas gerais e de suas misturas Determination of the physical-chemical composition of homemade cachaças produced in the South of Minas Gerais and their mixtures

    Directory of Open Access Journals (Sweden)

    Fernando José Vilela

    2007-08-01

    Full Text Available Este trabalho teve por objetivo a determinação da composição físico-química de cachaças artesanais produzidas no sul do Estado de Minas Gerais e suas misturas. Foram analisados os teores de etanol, acidez volátil, aldeídos, cobre, ésteres, álcoois superiores totais e metanol, além dos álcoois propanol-1, isobutanol e 3-metil-butanol-1. Os resultados apresentam o perfil peculiar desta bebida, que apresentou teores satisfatórios de álcoois superiores, ésteres e aldeídos. O teor de cobre apresenta-se como preocupante já que algumas amostras excederam o limite de 5 mg.L-1. A produção de misturas foi estudada e esta apresenta-se como uma alternativa viável ao produtor e cooperativas.The present study sought the physical-chemical composition of homemade cachaças produced in the south of the state Minas Gerais and of mixtures of the same cachaça samples. The ethanol, aldehyde, copper, higher alcohol, volatile acid and methanol concentrations were determined, in addition to the individual propanol, 2-methyl-1-propanol and 3-methyl-1-butanol concentrations. The results demonstrated the characteristic profile of this beverage, which presented satisfactory concentrations of higher alcohols, esters, and aldehydes. The copper concentrations of some samples exceeded the limit of 5 mg. L-1. The mixtures produced from some of the cachaça samples presented a viable alternative for the producers and cooperatives because the concentrations of the components were more adequate for exportation.

  6. CHEMICAL COMPOUNDS FOR METAL SHAPING

    Science.gov (United States)

    ALLOYS, *CHEMICAL MILLING, *METALS, *REFRACTORY MATERIALS, AIRCRAFT, ALUMINUM ALLOYS, CARBOXYMETHYLCELLULOSE , CHEMICALS, CHROMIUM ALLOYS, GELS, HEAT...RESISTANT ALLOYS, MATERIALS, MOLYBDENUM ALLOYS, NICKEL ALLOYS, NIOBIUM, POROUS MATERIALS, PROCESSING, PRODUCTION , SOLIDS, SOLUTIONS(MIXTURES), STAINLESS STEEL, STEEL, STRUCTURES, TANTALUM, TITANIUM ALLOYS, VANADIUM ALLOYS.

  7. Steady-state organization of binary mixtures by active impurities

    DEFF Research Database (Denmark)

    Sabra, Mads Christian; Gilhøj, Henriette; Mouritsen, Ole G.

    1998-01-01

    The structural reorganization of a phase-separated binary mixture in the presence of an annealed dilution of active impurities is studied by computer-simulation techniques via a simple two-dimensional lattice-gas model. The impurities, each of which has two internal states with different affinity...

  8. Sensitivity of Some Explosive/Brine Mixtures

    Science.gov (United States)

    1980-08-01

    concentration in brine mixtures. 3 Friction test results of brine mixtures. 10 4 Thermal test results of brine mixtures. 11 Li 71 - INTRODUCTION A...also carried out on these impact insensitive mixtures. Of the seven mixtures only the 15% M28-Comp. B sample passed the thermal test , since smoking

  9. Internal combustion engine

    Energy Technology Data Exchange (ETDEWEB)

    Helmich, M.J.; Hoagland, M.C.; Hubbard, R.L.; Schaub, F.S.

    1981-12-22

    A method of combusting natural gas fuel in a two cycle, turbocharged internal combustion engine substantially reduces the production of nitrogen-oxygen emissions. An improved turbocharger design provides increased air charging pressure, produces a controlled lean air/fuel mixture and lowers peak combustion temperatures. A jet cell ignition device ensures uniform, reliable ignition of the lean air/fuel mixture under all operating conditions and the lean air/fuel mixture in turn encourages complete fuel combustion and provides excellent combustion characteristics with methane, ethane and heavier paraffinic hydrocarbon fuels. These structural modifications and adjustment of other operating parameters combine to reduce nitric oxide (NO) and nitrogen dioxide (NO/sub 2/) emissions by as much as 75% while effecting only a negligible increase in fuel consumption.

  10. Estabilização química do subleito de estradas: influência do tempo decorrido entre a mistura e a compactação na resistência mecânica de misturas solo-RBI Grade 81 Chemical stabilization of road subgrade: influence of elapsed time between mixture and compaction on mechanical strength of soil-RBI Grade 81 mixtures

    Directory of Open Access Journals (Sweden)

    Tiago Pinto da Trindade

    2005-06-01

    Full Text Available Este artigo aborda o estudo da influência do tempo decorrido entre mistura e compactação na resistência mecânica de três solos da Zona da Mata Norte de Minas Gerais, Brasil, quando estabilizados com 4% de RBI Grade 81, em relação ao peso de solo seco. Um solo residual maduro (solo 1 e dois solos residuais jovens (solos 2 e 3 de gnáisse foram utilizados no presente estudo. O programa de ensaios de laboratório englobou: (i tempos decorridos entre mistura e compactação: 0, 4, 8 e 24 horas; (ii energia de compactação: Proctor Modificado; (iii período de cura das misturas: 7 dias; e (iv determinação da resistência mecânica: média de três determinações da resistência à compressão não-confinada. Os resultados desta pesquisa indicam que: (i o tempo decorrido entre mistura e compactação dos corpos-de-prova influenciou significativamente o parâmetro resistência à compressão não confinada das misturas; (ii 4 horas foi o tempo ótimo entre mistura e compactação para as misturas dos solos 1 e 2 com RBI Grade 81; e (iii no solo 3, foi observado um melhor resultado para a compactação imediatamente após a mistura.This paper describes the study of the influence of time between mixture and compaction in the mechanical strength of three soils from ";Zona da Mata Norte";, Minas Gerais, Brazil, stabilized with 4% of RBI Grade 81. One mature (soil 1 and two young (soils 2 and 3 gneiss residual soils were used throughout the study. The laboratory testing program consisted of the following steps: (i elapsed times between mixture and compaction: 0, 4, 8 and 24 hours; (ii mixture specimen compaction effort: Modified Proctor; (iii mixture specimen curing time: 7 days in acclimatized room; (iv determination of mechanical strength: average of three determinations of unconfined compression strength. The testing data supported that: (i the elapsed time between mixture and specimen compaction affected significantly the mixture mechanical

  11. Internal Active Thermal Control System (IATCS) Sodium Bicarbonate/Carbonate Buffer in an Open Aqueous Carbon Dioxide System and Corollary Electrochemical/Chemical Reactions Relative to System pH Changes

    Science.gov (United States)

    Stegman, Thomas W.; Wilson, Mark E.; Glasscock, Brad; Holt, Mike

    2014-01-01

    The International Space Station (ISS) Internal Active Thermal Control System (IATCS) experienced a number of chemical changes driven by system absorption of CO2 which altered the coolant’s pH. The natural effects of the decrease in pH from approximately 9.2 to less than 8.4 had immediate consequences on system corrosion rates and corrosion product interactions with specified coolant constituents. The alkalinity of the system was increased through the development and implementation of a carbonate/bicarbonate buffer that would increase coolant pH to 9.0 – 10.0 and maintain pH above 9.0 in the presence of ISS cabin concentrations of CO2 up to twenty times higher than ground concentrations. This paper defines how a carbonate/bicarbonate buffer works in an open carbon dioxide system and summarizes the analyses performed on the buffer for safe and effective application in the on-orbit system. The importance of the relationship between the cabin environment and the IATCS is demonstrated as the dominant factor in understanding the system chemistry and pH trends before and after addition of the carbonate/bicarbonate buffer. The paper also documents the corollary electrochemical and chemical reactions the system has experienced and the rationale for remediation of these effects with the addition of the carbonate/bicarbonate buffer.

  12. On the use of mixture toxicity assessment in REACH and the water framework directive

    DEFF Research Database (Denmark)

    Syberg, Kristian; Jensen, T.S.; Cedergreen, Nina;

    2009-01-01

      This review seeks to connect the scientific theory of mixture toxicity to its implementation within different regulatory frameworks. The aim is to demonstrate how mixture toxicity assessment can be more thoroughly integrated into the European chemical regulations, REACH and the Water Framework ...

  13. Evaluation on the process challenge device and internal chemical indicators used for the detection of steam sterilization%PCD批量检测与化学指示卡检测灭菌效果的比较

    Institute of Scientific and Technical Information of China (English)

    林娟; 王海花

    2012-01-01

    目的 比较PCD批量检测及包内化学指示卡在高压灭菌质量监控中的可靠性,为医院供应室灭菌质量监控提供参考.方法 利用批量检测系统PCD包内化学指示卡、生物指示卡3种质控方式对高压灭菌质量进行监控,记录数据并进行分析.结果 自2010年1月~2010年12月期间,该院供应室共灭菌405次,PCD检测化学指示卡405张,其中合格399张;405批次灭菌中共放置生物检测卡2430张,其中有效2419张.PCD检测合格的399批次中,生物监测卡(2394张)全部显示合格;PCD检测不合格的6个批次灭菌中,有8张生物检测卡显示灭菌失败.PCD检测合格的399批次中包内化学指示卡63840张,合格63019张,显示不合格731张,其中335张出现于玻璃器皿包中,396张出现于金属类包中,布类包中均未发现有不合格包内化学指示卡.结论 PCD批量检测对灭菌效果较包内化学指示卡的指示效果可靠,值得推广.%OBJECTIVE To evaluate the sterilization monitoring of Process Challenge Device and Internal chemical indicators, and to provide laboratory data for quality monitoring and management. METHODS Three methods were used for the sterilization monitoring at the same lime which included Process Challenge Device, Internal chemical indicators and bioindicators. The records were analyzed. RESULTS 405 sterilization happened during 2010. We got 405 biochemical indicators bom PCD of which 399 indicated success and 6 indicated failure. 2 430 bioindicators were used in the 405 sterilizations of which 2 419 indicated success. All of the 2 394 bioindicators gave the same result among the 399 successful sterilizations indicated by PCD and 8 bioindicators gave the failure result among the 6 failed sterilizations indicated by PCD. Among the 399 sterilization, 63 840 Internal chemical indicators were got of which 63 019 gave successful indication and the other 731 gave failed indication.396 failed Internal chemical indicators were from

  14. Analysis of asphalt mixtures on town roads

    OpenAIRE

    Glavica, Primož

    2006-01-01

    Asphalt mixtures are most commonly used composite for construction of top layers of different drive ways. By definition asphalt mixtures are composed of crushed rock, fill, bitumen and additives. Percentage of individual components wary according to the purpose asphalt mixture is to be used for. Asphalt mixtures must be capable of enduring different types of load. According to the type of load asphalt mixtures are divided into asphalt mixtures used for supporting layers and asp...

  15. Separation of gas mixtures by supported complexes

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, D.A.; Lilga, M.A.; Hallen, R.T.; Lyke, S.E.

    1986-08-01

    The goal of this program is to determine the feasibility of solvent-dissolved coordination complexes for the separation of gas mixtures under bench-scale conditions. In particular, mixtures such as low-Btu gas are examined for CO and H/sub 2/ separation. Two complexes, Pd/sub 2/(dpm)/sub 2/Br/sub 2/ and Ru(CO)/sub 2/(PPh/sub 3/)/sub 3/, were examined in a bench-scale apparatus for the separation of binary (CO-N/sub 2/ or H/sub 2/-N/sub 2/) and quinary (H/sub 2/, CO, CO/sub 2/, CH/sub 4/, and N/sub 2/) mixtures. The separation of CO-N/sub 2/ was enhanced by the presence of the palladium complex in the 1,1,2-trichloroethane (TCE) solvent, especially at high gas and low liquid rates. The five-component gas mixture separation with the palladium complex in TCE provided quite unexpected results based on physical solubility and chemical coordination. The complex retained CO, while the solvent retained CO/sub 2/, CH/sub 4/, and N/sub 2/ to varying degrees. This allowed the hydrogen content to be enhanced due to its low solubility in TCE and inertness to the complex. Thus, a one-step, hydrogen separation can be achieved from gas mixtures with compositions similar to that of oxygen-blown coal gas. A preliminary economic evaluation of hydrogen separation was made for a system based on the palladium complex. The palladium system has a separation cost of 50 to 60 cents/MSCF with an assumed capital investment of $1.60/MSCF of annual capacity charged at 30% per year. This assumes a 3 to 4 year life for the complex. Starting with a 90% hydrogen feed, PSA separation costs are in the range of 30 to 50 cents/MSCF. The ruthenium complex was not as successful for hydrogen or carbon monoxide separation due to unfavorable kinetics. The palladium complex was found to strip hydrogen gas from H/sub 2/S. The complex could be regenerated with mild oxidants which removed the sulfur as SO/sub 2/. 24 refs., 26 figs., 10 tabs.

  16. Advances in chemical physics

    CERN Document Server

    Rice, Stuart A

    2012-01-01

    The Advances in Chemical Physics series-the cutting edge of research in chemical physics The Advances in Chemical Physics series provides the chemical physics and physical chemistry fields with a forum for critical, authoritative evaluations of advances in every area of the discipline. Filled with cutting-edge research reported in a cohesive manner not found elsewhere in the literature, each volume of the Advances in Chemical Physics series presents contributions from internationally renowned chemists and serves as the perfect supplement to any advanced graduate class devoted to the study o

  17. Advances in chemical Physics

    CERN Document Server

    Rice, Stuart A

    2011-01-01

    The Advances in Chemical Physics series-the cutting edge of research in chemical physics The Advances in Chemical Physics series provides the chemical physics and physical chemistry fields with a forum for critical, authoritative evaluations of advances in every area of the discipline. Filled with cutting-edge research reported in a cohesive manner not found elsewhere in the literature, each volume of the Advances in Chemical Physics series offers contributions from internationally renowned chemists and serves as the perfect supplement to any advanced graduate class devoted to the study of che

  18. Advances in chemical physics

    CERN Document Server

    Rice, Stuart A

    2011-01-01

    The Advances in Chemical Physics series-the cutting edge of research in chemical physics The Advances in Chemical Physics series provides the chemical physics and physical chemistry fields with a forum for critical, authoritative evaluations of advances in every area of the discipline. Filled with cutting-edge research reported in a cohesive manner not found elsewhere in the literature, each volume of the Advances in Chemical Physics series offers contributions from internationally renowned chemists and serves as the perfect supplement to any advanced graduate class devoted to the study of che

  19. Characteristics of The Fillers Used for Realizing the Asphalt Mixtures in Romania

    Directory of Open Access Journals (Sweden)

    Irina-Mihaela Dămiean

    2005-01-01

    Full Text Available This paper presents the lab results for four types of filler used in producing the asphalt mixture in Romania, as well as other physical-chemical characteristics of a new type of filler, derivate of the grinding of the bituminous shists through a ball mill/crusher. Knowing these physical-chemical characteristics is crucial for asphalt mixtures due to the complex purpose of the filler.

  20. Analysis of functional effects of a mixture of five pesticides using a ray design.

    Science.gov (United States)

    Gennings, Chris; Carter, W Hans; Casey, Michelle; Moser, Virginia; Carchman, Richard; Simmons, Jane Ellen

    2004-11-01

    The protection of human health from the adverse effects of cumulative environmental exposure to chemical mixtures is an important issue. Of particular interest is the detection and characterization of interaction among chemicals in complex mixtures. Response surface methodology, often supported by factorial designs, is the classical statistical experimental approach. Fixed-ratio ray designs, which may include the use of single chemical data in addition to data along mixture ray(s), have been proposed as an alternative approach. Such designs permit a reduction in the amount of experimental effort when the region of interest can be restricted to exposure-relevant mixing ratios. A 'single chemicals required' (SCR) approach and a 'single chemicals not required' (SCNR) approach are both described. The methods are illustrated with a five-chemical mixture of organophosphorus pesticides-acephate (ACE), diazinon (DIA), chlorpyrifos (CPF), malathion (MAL) and dimethoate (DIM). Their relative proportions in the mixture were based on the relative dietary human exposure estimates of each chemical as projected by the U.S. EPA Dietary Exposure Evaluation Model (DEEM). Use of the SCR and SCNR methods for binary endpoints are demonstrated using a dichotomized gait score as an indication of toxicity. For both methods, the overall hypothesis of additivity was rejected, indicating significant departure from additivity when the five pesticides were combined at the specified mixing ratio. By comparison of the predicted response under additivity to the modeled response of the experimental mixture data this departure from additivity was characterized as synergy (greater than additive toxicity). To examine the influence of malathion in the mixture, it was removed from the five-pesticide mixture (full ray) and the remaining four chemicals (reduced ray) were combined at the same relative proportions used in the full fixed-ratio ray There was not a significant departure from additivity along

  1. Ammonia/Hydrogen Mixtures in an SI-Engine

    DEFF Research Database (Denmark)

    Mørch, Christian Sandersen; Bjerre, Andreas; Gøttrup, Morten Piil

    2011-01-01

    In recent years there has been increasing focus on using metal ammine complexes for ammonia storage. In this paper a fuel system for ammonia fuelled internal combustion engines using metal ammine complexes as ammonia storage is analyzed. The use of ammonia/hydrogen mixtures as an SI-engine fuel...... is investigated in the same context. Ammonia and hydrogen were introduced into the intake manifold of a CFR-engine. Series of experiments with varying excess air ratio and different ammonia to hydrogen ratios was conducted. This showed that a fuel mixture with 10 vol.% hydrogen performs best with respect...

  2. Inorganic salt mixtures as electrolyte media in fuel cells

    Science.gov (United States)

    Angell, Charles Austen (Inventor); Belieres, Jean-Philippe (Inventor); Francis-Gervasio, Dominic (Inventor)

    2012-01-01

    Fuel cell designs and techniques for converting chemical energy into electrical energy uses a fuel cell are disclosed. The designs and techniques include an anode to receive fuel, a cathode to receive oxygen, and an electrolyte chamber in the fuel cell, including an electrolyte medium, where the electrolyte medium includes an inorganic salt mixture in the fuel cell. The salt mixture includes pre-determined quantities of at least two salts chosen from a group consisting of ammonium trifluoromethanesulfonate, ammonium trifluoroacetate, and ammonium nitrate, to conduct charge from the anode to the cathode. The fuel cell includes an electrical circuit operatively coupled to the fuel cell to transport electrons from the cathode.

  3. 75 FR 53867 - Additions to Listing of Exempt Chemical Mixtures

    Science.gov (United States)

    2010-09-02

    ...% acetonitrile), dimethylformamide, ethylene glycol, isopropanol, methanol, methanol/water (50:50), methanol..., acetonitrile, acetonitrile: water (>= 50% acetonitrile), dimethylformamide, ethylene glycol, isopropanol...), dimethylformamide, ethylene glycol, isopropanol, methanol, methanol/water (50:50), methanol/dimethyl sulfoxide...

  4. 75 FR 37301 - Exempt Chemical Mixtures Containing Gamma-Butyrolactone

    Science.gov (United States)

    2010-06-29

    ...-Rape Drug Prohibition Act of 2000, on February 18, 2000. GBL and GHB induce a sense of euphoria and... GHB. For this reason, abusers or predators seeking to use GBL on their victims routinely substitute... recovered. After examination of the comments on the ANPRM and after weighing the risk of diversion,...

  5. Percutaneous Absorption of Chemical Mixtures Relevant to the Gulf War

    Science.gov (United States)

    2000-02-01

    Millennium version 32 software. A Waters SymmetryShield RP18 (3.5-micron, 4.6x150mm) column was used for the separations. The mobile phase consisted...Millennium version 32 software. A Waters SymmetryShield RP18 (3.5-micron, 4.6x15Omm) column was used for the separations. The mobile phase consisted

  6. Chemical Characterization and Toxicologic Evaluation of Airborne Mixtures

    Science.gov (United States)

    1981-04-01

    that had healed smoothly. One rat’s epiglottis was essen- tially absent, with only a small, smooth, raised ridge in its place. Two rats had small...all had laryn- geal edema. In two if these, the epiglottis was so severely eroded as to be hi almost absent. Three rats that survived for 14 days and...were killed had slight to moderate erosive lesions of the epiglottis . At the highest dose (8.46 mg/2 for 1 hour), six rats died by the end of exposure

  7. Revision of Import and Export Requirements for Controlled Substances, Listed Chemicals, and Tableting and Encapsulating Machines, Including Changes To Implement the International Trade Data System (ITDS); Revision of Reporting Requirements for Domestic Transactions in Listed Chemicals and Tableting and Encapsulating Machines; and Technical Amendments. Final rule.

    Science.gov (United States)

    2016-12-30

    The Drug Enforcement Administration is updating its regulations for the import and export of tableting and encapsulating machines, controlled substances, and listed chemicals, and its regulations relating to reports required for domestic transactions in listed chemicals, gamma-hydroxybutyric acid, and tableting and encapsulating machines. In accordance with Executive Order 13563, the Drug Enforcement Administration has reviewed its import and export regulations and reporting requirements for domestic transactions in listed chemicals (and gamma-hydroxybutyric acid) and tableting and encapsulating machines, and evaluated them for clarity, consistency, continued accuracy, and effectiveness. The amendments clarify certain policies and reflect current procedures and technological advancements. The amendments also allow for the implementation, as applicable to tableting and encapsulating machines, controlled substances, and listed chemicals, of the President's Executive Order 13659 on streamlining the export/import process and requiring the government-wide utilization of the International Trade Data System (ITDS). This rule additionally contains amendments that implement recent changes to the Controlled Substances Import and Export Act (CSIEA) for reexportation of controlled substances among members of the European Economic Area made by the Improving Regulatory Transparency for New Medical Therapies Act. The rule also includes additional substantive and technical and stylistic amendments.

  8. Evaluation of Program for International Student Assessment in Chemical Science Literacy%PISA对化学学科素养的测评

    Institute of Scientific and Technical Information of China (English)

    王艳

    2014-01-01

    本文结合具体案例介绍了PISA测评化学学科素养的特点,提出PISA试题在化学出题上,对创设情境的注重、互动性的问答方式以及开放性的评分方式都是鼓励学生应用知识、分析解决实际问题的好借鉴。%This article introduces the characteristic of the evaluation of scientific literacy of chemistry in the program for international student assessment (PISA) based on the specific case. And it proposed that PISA in designing questions, creating situations, paying attention to the way of interactive-interlocution, and opening the scoring method is the good example to encourage students to use knowledge to analyze and solve practical problems.

  9. Marangoni Convection in Binary Mixtures

    CERN Document Server

    Zhang, J; Oron, A; Behringer, Robert P.; Oron, Alexander; Zhang, Jie

    2006-01-01

    Marangoni instabilities in binary mixtures are different from those in pure liquids. In contrast to a large amount of experimental work on Marangoni convection in pure liquids, such experiments in binary mixtures are not available in the literature, to our knowledge. Using binary mixtures of sodium chloride/water, we have systematically investigated the pattern formation for a set of substrate temperatures and solute concentrations in an open system. The flow patterns evolve with time, driven by surface-tension fluctuations due to evaporation and the Soret effect, while the air-liquid interface does not deform. A shadowgraph method is used to follow the pattern formation in time. The patterns are mainly composed of polygons and rolls. The mean pattern size first decreases slightly, and then gradually increases during the evolution. Evaporation affects the pattern formation mainly at the early stage and the local evaporation rate tends to become spatially uniform at the film surface. The Soret effect becomes i...

  10. Mixtures of skewed Kalman filters

    KAUST Repository

    Kim, Hyoungmoon

    2014-01-01

    Normal state-space models are prevalent, but to increase the applicability of the Kalman filter, we propose mixtures of skewed, and extended skewed, Kalman filters. To do so, the closed skew-normal distribution is extended to a scale mixture class of closed skew-normal distributions. Some basic properties are derived and a class of closed skew. t distributions is obtained. Our suggested family of distributions is skewed and has heavy tails too, so it is appropriate for robust analysis. Our proposed special sequential Monte Carlo methods use a random mixture of the closed skew-normal distributions to approximate a target distribution. Hence it is possible to handle skewed and heavy tailed data simultaneously. These methods are illustrated with numerical experiments. © 2013 Elsevier Inc.

  11. Electrochemical concentration measurements for multianalyte mixtures in simulated electrorefiner salt

    Science.gov (United States)

    Rappleye, Devin Spencer

    The development of electroanalytical techniques in multianalyte molten salt mixtures, such as those found in used nuclear fuel electrorefiners, would enable in situ, real-time concentration measurements. Such measurements are beneficial for process monitoring, optimization and control, as well as for international safeguards and nuclear material accountancy. Electroanalytical work in molten salts has been limited to single-analyte mixtures with a few exceptions. This work builds upon the knowledge of molten salt electrochemistry by performing electrochemical measurements on molten eutectic LiCl-KCl salt mixture containing two analytes, developing techniques for quantitatively analyzing the measured signals even with an additional signal from another analyte, correlating signals to concentration and identifying improvements in experimental and analytical methodologies. (Abstract shortened by ProQuest.).

  12. Molecular Thermodynamics for Chemical Process Design

    Science.gov (United States)

    Prausnitz, J. M.

    1976-01-01

    Discusses that aspect of thermodynamics which is particularly important in chemical process design: the calculation of the equilibrium properties of fluid mixtures, especially as required in phase-separation operations. (MLH)

  13. Results of Section 4 Chemical Testing

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Toxic Substances Control Act (TSCA) requires that data be developed on the effect of chemical substances and mixtures on health and the environment. This data...

  14. Amaranth lunasin-like peptide internalizes into the cell nucleus and inhibits chemical carcinogen-induced transformation of NIH-3T3 cells.

    Science.gov (United States)

    Maldonado-Cervantes, Enrique; Jeong, Hyung Jin; León-Galván, Fabiola; Barrera-Pacheco, Alberto; De León-Rodríguez, Antonio; González de Mejia, Elvira; de Lumen, Ben O; Barba de la Rosa, Ana P

    2010-09-01

    Because an unbalanced diet is an important risk factor for several illnesses, interest has increased in finding novel health-promoting foods. Amaranth produces seeds that not only have substantial nutritional properties but that also contain phytochemical compounds as rutin and nicotiflorin and peptides with antihypertensive and anticarcinogenic activities. We report that a cancer-preventive peptide in amaranth has activities similar to those of soybean lunasin. The amaranth lunasin-like peptide, however, requires less time than the soybean lunasin to internalize into the nucleus of NIH-3T3 cells, and inhibits histone acetylation (H(3) and H(4) in a 70 and 77%, respectively). The amaranth lunasin-like peptide inhibited the transformation of NIH-3T3 cells to cancerous foci. The open reading frame (ORF) of amaranth lunasin corresponds to a bifunctional inhibitor/lipid-transfer protein (LTP). LTPs are a family of proteins that in plants are implicated in different functions, albeit all linked to developmental processes and biotic and abiotic stress resistance. Our results open new intriguing questions about the function of lunasin in plants and support that amaranth is a food alternative containing natural peptides with health-promoting benefits.

  15. Rationale and Methods for Archival Sampling and Analysis of Atmospheric Trace Chemical Contaminants On Board Mir and Recommendations for the International Space Station

    Science.gov (United States)

    Perry, J. L.; James, J. T.; Cole, H. E.; Limero, T. F.; Beck, S. W.

    1997-01-01

    Collection and analysis of spacecraft cabin air samples are necessary to assess the cabin air quality with respect to crew health. Both toxicology and engineering disciplines work together to achieve an acceptably clean cabin atmosphere. Toxicology is concerned with limiting the risk to crew health from chemical sources, setting exposure limits, and analyzing air samples to determine how well these limits are met. Engineering provides the means for minimizing the contribution of the various contaminant generating sources by providing active contamination control equipment on board spacecraft and adhering to a rigorous material selection and control program during the design and construction of the spacecraft. A review of the rationale and objectives for sampling spacecraft cabin atmospheres is provided. The presently-available sampling equipment and methods are reviewed along with the analytical chemistry methods employed to determine trace contaminant concentrations. These methods are compared and assessed with respect to actual cabin air quality monitoring needs. Recommendations are presented with respect to the basic sampling program necessary to ensure an acceptably clean spacecraft cabin atmosphere. Also, rationale and recommendations for expanding the scope of the basic monitoring program are discussed.

  16. Taylor dispersion analysis of mixtures.

    Science.gov (United States)

    Cottet, Hervé; Biron, Jean-Philippe; Martin, Michel

    2007-12-01

    Taylor dispersion analysis (TDA) is a fast and simple method for determining hydrodynamic radii. In the case of sample mixtures, TDA, as the other nonseparative methods, leads to an average diffusion coefficient on the different molecules constituting the mixture. We set in this work the equations giving, on a consistent basis, the average values obtained by TDA with detectors with linear response functions. These equations confronted TDA experiments of sample mixtures containing different proportions of a small molecule and a polymer standard. Very good agreement between theory and experiment was obtained. In a second part of this work, on the basis of monomodal or bimodal molar mass distributions of polymers, the different average diffusion coefficients corresponding to TDA were compared to the z-average diffusion coefficient (D(z)) obtained from dynamic light scattering (DLS) experiments and to the weight average diffusion coefficient (D(w)). This latter value is sometimes considered as the most representative of the sample mixture. From these results, it appears that, for monomodal distribution and relatively low polydispersity (I = 1.15), the average diffusion coefficient generally derived from TDA is very close to Dw. However, for highly polydisperse samples (e.g., bimodal polydisperse distributions), important differences could be obtained (up to 35% between TDA and D(w)). In all the cases, the average diffusion coefficient obtained by TDA for a mass concentration detector was closer to the Dw value than the z-average obtained by DLS.

  17. Direct regeneration of recycled cathode material mixture from scrapped LiFePO4 batteries

    Science.gov (United States)

    Li, Xuelei; Zhang, Jin; Song, Dawei; Song, Jishun; Zhang, Lianqi

    2017-03-01

    A new green recycling process (named as direct regeneration process) of cathode material mixture from scrapped LiFePO4 batteries is designed for the first time. Through this direct regeneration process, high purity cathode material mixture (LiFePO4 + acetylene black), anode material mixture (graphite + acetylene black) and other by-products (shell, Al foil, Cu foil and electrolyte solvent, etc.) are recycled from scrapped LiFePO4 batteries with high yield. Subsequently, recycled cathode material mixture without acid leaching is further directly regenerated with Li2CO3. Direct regeneration procedure of recycled cathode material mixture from 600 to 800 °C is investigated in detail. Cathode material mixture regenerated at 650 °C display excellent physical, chemical and electrochemical performances, which meet the reuse requirement for middle-end Li-ion batteries. The results indicate the green direct regeneration process with low-cost and high added-value is feasible.

  18. Lesson learned case study: What the history of ozone depelting chemical phaseout may teach us about how to approach international climate change policy

    Energy Technology Data Exchange (ETDEWEB)

    Younis, S.E. [Conceptual Engineering Group, Inc., Crofton, MD (United States); Verdonik, D.P. [Hughes Associates, Inc., Baltimore, MD (United States)

    1997-12-31

    The world approached the production phaseout of ozone depleting chemicals conservatively under the Vienna Convention. The initial tasks were to recognize the problem within the science field and make political leaders and people aware that the problem existed and was a real threat to environmental stability. Several years later, Meetings of the Parties to the Montreal Protocol to Protect the Stratospheric Ozone Layer began occurring regularly. Long term goals on production reduction levels of chlorofluorocarbons (CFCs) and halons were set. Rapid acceleration in production phaseout dates were implemented worldwide, impacting industry plans to research, develop, and implement replacements. The impacts were widespread from small cleaning processes to the defense of countries. The trials and tribulations that industries such as the foam, refrigeration, air conditioning, fire protection, and manufacturing industries have gone through to meet the accelerated challenges are great. This fight is not yet over. Alternatives have yet to be fully implemented, long term effects analysis are not yet completed, budgets have not caught up with the rapid phaseout, and supplies of ODCs are dwindling quickly, as well as increasing in cost at a rapid rate. This is being felt from car owner all the way up to the national defense of countries. The paper will briefly describe the historic events and developments that occurred to industry and the users, from a political, environmental, and business perspective. From this, valuable lessons can be learned and we can plan for the future well in advance, in order that we are not caught off guard again. A very real environmental problem exists with global climate change. This is being increasingly recognized by both political leaders and citizens alike. From what we have seen with ODC phaseout, we can potentially project what course the future.

  19. Hypolipidemic effect of vegetable and cereal dietary mixtures from Egyptian sources

    Directory of Open Access Journals (Sweden)

    Rashed, Magdy M.

    2010-09-01

    Full Text Available Hyperlipidemia is a predominant risk factor for atherosclerosis and associated cardiovascular diseases (CVD. The international guidelines issued by the World Health Organization recommend a reduction in dietary saturated fat and cholesterol intake as a means to prevent hypercholesterolemia and CVD; however, only limited data are available on the benefits of vegetable consumption on CVD risk factors. The aim of this study was to prepare two powder mixtures containing vegetables and cereals and to evaluate their effect in hyperlipidemic rats. The first mixture was prepared from whole wheat, cabbage, parsley and pepper, while the second mixture was prepared from whole wheat, red beet root, parsley and pepper. Whole wheat was used as a source of dietary fiber, while cabbage and beetroot were used as sources of glucosinolates (GLS and betalains respectively as well as dietary fiber. The chemical compositions of these mixtures were determined. The safety of these mixtures was also evaluated by examining liver and kidney functions. The chemical compositions of the powder mixtures revealed that mixtures (1 and (2 contain 19.1% and 13.3% protein, 2.1% and 2.5 % fat, 69.6% and 77.5% carbohydrates, 1.8% and 1.2% crude fibers, 7.4% and 5.5% ash and 18.3% and 16.8% dietary fibers respectively. Vitamin E was 7.4 and 4.5 mg/100g in mixtures (1 and (2 respectively. β-carotene was 830 and 786μg/100g in mixtures (1 and (2 respectively. Total phenolic compounds were 1910 and 1710 mg as gallic acid equivalents/100g in mixtures (1 and (2 respectively. The results of the animal experiment showed a non-significant reduction in final body weight and body weight gain in rats fed the control diet containing mixture (1 or (2 when compared with different groups. Rats fed the control diet containing mixture (1 or (2 showed a significant reduction in plasma total lipids, T-Ch, LDL-Ch, TG and the ratio of T-Ch /HDLCh in different degrees, while HDL-Ch increased

  20. Proteomics based compositional analysis of complex cellulase-hemicellulase mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Chundawat, Shishir P.; Lipton, Mary S.; Purvine, Samuel O.; Uppugundla, Nirmal; Gao, Dahai; Balan, Venkatesh; Dale, Bruce E.

    2011-10-07

    Efficient deconstruction of cellulosic biomass to fermentable sugars for fuel and chemical production is accomplished by a complex mixture of cellulases, hemicellulases and accessory enzymes (e.g., >50 extracellular proteins). Cellulolytic enzyme mixtures, produced industrially mostly using fungi like Trichoderma reesei, are poorly characterized in terms of their protein composition and its correlation to hydrolytic activity on cellulosic biomass. The secretomes of commercial glycosyl hydrolase producing microbes was explored using a proteomics approach with high-throughput quantification using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Here, we show that proteomics based spectral counting approach is a reasonably accurate and rapid analytical technique that can be used to determine protein composition of complex glycosyl hydrolase mixtures that also correlates with the specific activity of individual enzymes present within the mixture. For example, a strong linear correlation was seen between Avicelase activity and total cellobiohydrolase content. Reliable, quantitative and cheaper analytical methods that provide insight into the cellulosic biomass degrading fungal and bacterial secretomes would lead to further improvements towards commercialization of plant biomass derived fuels and chemicals.

  1. Enhance international competitive power in the chemical industry to meet challenges from economic globalization%提高化学工业国际竞争力迎接经济全球化的挑战

    Institute of Scientific and Technical Information of China (English)

    郭镇华; 李丹

    2001-01-01

    As is seen from the analysis of the development trends of chemical industry globalization,chemical enterprises need to enhance their international competitive power to meet new challenges from the globalization.Among others,improving innovation and management is the critical method.Three issues concerned include the analysis of the competitive environment in industrial sectors and enterprises,the use of the advanced methodology and the improvement on the information system.%通过分析化学工业全球化的发展趋势,指出化工企业必须提高其国际竞争力以迎接全球化带来的挑战。为了提高企业竞争力,改进创新能力和管理水平是主要途径。以下3方面应予以重点关注:分析竞争环境、使用先进方法和改进信息系统。

  2. Evaluation of Hydrated Lime Filler in Asphalt Mixtures

    Directory of Open Access Journals (Sweden)

    Mohammed Abbas Hasan Al-Jumaily

    2008-01-01

    Full Text Available Mineral filler is one of important materials and affecting on properties and quality of asphalt mixtures .There are different types of mineral filler depended on cost and quality , the matter encourages us to achieve this study to evaluate hydrated lime filler effects on properties of asphalt mixes related with strength and durability. Conventional asphaltic concrete mixtures with Portland cement and soft sandstone fillers and mixtures modified with hydrated lime were evaluated for their fundamental engineering properties as defined by Marshall properties , index of retained strength , indirect tensile strength , permanent deformation characteristics , and fatigue resistance .A typical dense graded mixture employed in construction of surface course pavement in Iraq in accordance with SCRB specifications was used .The materials used in this study included mineral aggregate materials (coarse and fine sizes were originally obtained from Najaf Sea quarries and two grades of asphalt cements produced from Daurah refinery which are D47 and D66 . The physical properties , stiffness modulus and chemical composition are evaluated for the recovered asphalt cement from prepared asphalt mixes containing various filler types .The paper results indicated that the addition of hydrated lime as mineral filler improved the permanent deformation characteristics and fatigue life and the use of hydrated lime will decrease the moisture susceptibility of the asphalt mixtures.

  3. Predicting toxicity of aromatic ternary mixtures to algae

    Institute of Scientific and Technical Information of China (English)

    LU GuangHua; WANG Chao; WANG PeiFang; YANG ChengZhi

    2009-01-01

    Aquatic ecosystems are often polluted with more than one type of contaminant, and information on the combined toxic effects of mixed pollutants on aquatic organisms is scarce at present. Acute toxicity of aromatic compounds and their ternary mixtures to the alga (Scenedesmus obliquus) was determined by the algae growth inhibition test. The median effective concentration (EC_(50)) value for a single aromatic compound and EC_(50mix) values for mixtures were obtained, the logarithm of n-octanol/water partition coefficient (logP_(mix)) and the frontier orbital energy gap (△E_(mix) for mixtures were calculated. Based on the quantitative structure-activity relationship model for single chemical toxicity log(1/EC_(50)) =0.426logP-1.150△E+12.61 (n=15, R~2=0.917 and Q~2=0.878), the following two-descriptor model was developed for the ternary mixture toxicity of aromatic compounds: log(1/EC_(50mix))=O.68210gP_(mix)-O.367△E_(mix)+ 4.971 (n=44, R~2-0.869 and Q~2=0.843). This model can be used to predict the combined toxicity of mixtures containing toxicants with different mechanisms of action.

  4. Application of mathematical statistics technology on internal quality control in chemical analysis laboratory%数理统计技术在化学分析实验室内部质量控制中的运用

    Institute of Scientific and Technical Information of China (English)

    郑卫东; 胡丹; 郑海峰

    2013-01-01

      Internal quality control procedures are established in the chemical analysis lab to ensure the con-sistently obtaining of accurate and reliable data. Mathematical statistics technology has been one of the main me-thods applied to internal quality control procedures. This paper analysed the difference of requirements and guides on mathematical statistics technology application in the lab’s internal quality control at home and abroad, and pointed out that related guides should be drafted as soon as possible. Series of application standards on mathematical statistics technology should be issued, and related publicity and training should been strengthened in our country.%  实验室建立内部质量控制体系以确保连续出具准确可靠的数据,数理统计技术是内部质量控制体系中使用的主要方法之一。本文分析了国际上著名组织在实验室内部质量控制中数理统计技术运用方面的要求和指南,并与国内的情况作了比较,提出我国应该尽快制定相关指南,出台系列数理统计技术在内部质量控制中的运用标准并加强相关的宣传、贯彻和培训。

  5. Chemical Emergencies

    Science.gov (United States)

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

  6. Experience in forming and core mixtures by Alphaset technology

    OpenAIRE

    I. Vasková; M. Smolková; J. Malik; Eperješi Š.

    2008-01-01

    Chemically bound mixtures have had the evolution effect upon the economical and quality aspects of the foundry operations since they presentation at the market. The higher output and significantly increased production efficiency of moulds and cores has lead to the material increase in the quality and profit of the foundries. It can be seen that in last several years the knowledge of bounds based on the organic resins has made enormous advances. The higher strength, improved properties under e...

  7. Molten fluoride mixtures as possible fission reactor fuels

    Energy Technology Data Exchange (ETDEWEB)

    Grimes, W.R.

    1978-01-01

    Molten mixtures of fluorides with UF/sub 4/ as a component have been used as combined fuel and primary heat transfer agent in experimental high-temperature reactors and have been proposed for use in breeders or converters of /sup 233/U from thorium. Such use places stringent and diverse demands upon the fluid fuel. A brief review of chemical behavior of molten fluorides is given to show some of their strengths and weaknesses for such service.

  8. HELLE: Health Effects of Low Level Exposures/ Gezondheidseffecten van lage blootstellingniveaus [International workshop: Influence of low level exposures to chemicals and radiation on human and ecological health

    Energy Technology Data Exchange (ETDEWEB)

    Schoten, Eert

    1998-11-26

    The Health Council is closely involved in establishing the scientific foundation of exposure limits for substances and radiation in order to protect public health. Through the years, the Council has contributed to the formulation of principles and procedures, both for carcinogenic and for noncarcinogenic agents. As a rule, the discussion with regard to the derivation of health-based recommended exposure limits centers around the appropriateness of extrapolation methods (What can be inferred from data on high exposure levels and on experimental animals?). Generally speaking, there is a lack of direct information on the health effects of low levels of exposure. Effects at these levels cannot usually be detected by means of traditional animal experiments or epidemiological research. The capacity of these analytical instruments to distinguish between ''signal'' and ''noise'' is inadequate in most cases. Annex B of this report contains a brief outline of the difficulties and the established methods for tackling this problem. In spite of this, the hope exists that the posited weak signals, if they are indeed present, can be detected by other means. The search will have to take place on a deeper level. In other words, effort must be made to discover what occurs at underlying levels of biological organization when organisms are exposed to low doses of radiation or substances. Molecular and cell biology provide various methods and techniques which give an insight into the processes within the cell. This results in an increase in the knowledge about the molecular and cellular effects of exposure to agents, or stated differently, the working mechanisms which form the basis of the health effects. Last year, the Health Council considered that the time was ripe to take stock of the state of knowledge in this field. To this end, an international working conference was held from 19 to 21 October 1997, entitled ''Health Effects of

  9. A four-step approach to evaluate mixtures for consistency with dose addition.

    Science.gov (United States)

    Hertzberg, Richard C; Pan, Yi; Li, Ruosha; Haber, Lynne T; Lyles, Robert H; Herr, David W; Moser, Virginia C; Simmons, Jane Ellen

    2013-11-16

    Mixture risk assessment is often hampered by the lack of dose-response information on the mixture being assessed, forcing reliance on component formulas such as dose addition. We present a four-step approach for evaluating chemical mixture data for consistency with dose addition for use in supporting a component based mixture risk assessment. Following the concepts in the U.S. EPA mixture risk guidance (U.S. EPA, 2000a,b), toxicological interaction for a defined mixture (all components known) is departure from a clearly articulated definition of component additivity. For the common approach of dose additivity, the EPA guidance identifies three desirable characteristics, foremost of which is that the component chemicals are toxicologically similar. The other two characteristics are empirical: the mixture components have toxic potencies that are fixed proportions of each other (throughout the dose range of interest), and the mixture dose term in the dose additive prediction formula, which we call the combined prediction model (CPM), can be represented by a linear combination of the component doses. A consequent property of the proportional toxic potencies is that the component chemicals must share a common dose-response model, where only the dose coefficients depend on the chemical components. A further consequence is that the mixture data must be described by the same mathematical function ("mixture model") as the components, but with a distinct coefficient for the total mixture dose. The mixture response is predicted from the component dose-response curves by using the dose additive CPM and the prediction is then compared with the observed mixture results. The four steps are to evaluate: (1) toxic proportionality by determining how well the CPM matches the single chemical models regarding mean and variance; (2) fit of the mixture model to the mixture data; (3) agreement between the mixture data and the CPM prediction; and (4) consistency between the CPM and the

  10. Binary mixtures of chiral gases

    CERN Document Server

    Presilla, Carlo

    2015-01-01

    A possible solution of the well known paradox of chiral molecules is based on the idea of spontaneous symmetry breaking. At low pressure the molecules are delocalized between the two minima of a given molecular potential while at higher pressure they become localized in one minimum due to the intermolecular dipole-dipole interactions. Evidence for such a phase transition is provided by measurements of the inversion spectrum of ammonia and deuterated ammonia at different pressures. In particular, at pressure greater than a critical value no inversion line is observed. These data are well accounted for by a model previously developed and recently extended to mixtures. In the present paper, we discuss the variation of the critical pressure in binary mixtures as a function of the fractions of the constituents.

  11. Atomistic Simulations of Bicelle Mixtures

    OpenAIRE

    Jiang, Yong; Wang, Hao; Kindt, James T.

    2010-01-01

    Mixtures of long- and short-tail phosphatidylcholine lipids are known to self-assemble into a variety of aggregates combining flat bilayerlike and curved micellelike features, commonly called bicelles. Atomistic simulations of bilayer ribbons and perforated bilayers containing dimyristoylphosphatidylcholine (DMPC, di-C14 tails) and dihexanoylphosphatidylcholine (DHPC, di-C6 tails) have been carried out to investigate the partitioning of these components between flat and curved microenvironmen...

  12. FRACTIONAL TRANSPORT OF SEDIMENT MIXTURES

    Institute of Scientific and Technical Information of China (English)

    Baosheng WU; Albert MOLINAS; Anping SHU

    2003-01-01

    A new method based on the Transport Capacity Fraction (TCF) concept is proposed to compute the fractional transport rates for nonuniform sediment mixtures in sand-bed channels. The TCF concept is derived from the understanding that the measurements and predictions of bed-material load are more accurate and reliable than the measurements and predictions of fractional loads. First the bed-material load is computed using an appropriate equation, then the fractional transport rates are determined by distributing the bed-material load into size groups through a transport capacity distribution function. For the computation of bed-material loads, the Aekers and White, Engelund and Hansen, and Yang equations are used in this study. Two new transport capacity distribution functions are developed for flows in sand-bed channels. The new expressions presented in this paper account for the sheltering and exposure effects that exist in mixtures. Comparisons with measured data show that the proposed method can significantly improve the predictions of fractional transport rates for nonuniform sediment mixtures.

  13. Mixture component effects on the in vitro dermal absorption of pentachlorophenol

    Energy Technology Data Exchange (ETDEWEB)

    Riviere, J.E.; Qiao, G.; Baynes, R.E.; Brooks, J.D. [Coll. of Veterinary Medicine, North Carolina State Univ., Raleigh, NC (United States); Mumtaz, M. [Agency for Toxic Substances and Disease Registry (ATSDR), Atlanta, GA (United States)

    2001-08-01

    Interactions between chemicals in a mixture and interactions of mixture components with the skin can significantly alter the rate and extent of percutaneous absorption, as well as the cutaneous disposition of a topically applied chemical. The predictive ability of dermal absorption models, and consequently the dermal risk assessment process, would be greatly improved by the elucidation and characterization of these interactions. Pentachlorophenol (PCP), a compound known to penetrate the skin readily, was used as a marker compound to examine mixture component effects using in vitro porcine skin models. PCP was administered in ethanol or in a 40% ethanol/60% water mixture or a 40% ethanol/60% water mixture containing either the rubefacient methyl nicotinate (MNA) or the surfactant sodium lauryl sulfate (SLS), or both MNA and SLS. Experiments were also conducted with {sup 14}C-labelled 3,3',4,4'-tetrachlorobiphenyl (TCB) and 3,3',4,4',5-pentachlorobiphenyl (PCB). Maximal PCP absorption was 14.12% of the applied dose from the mixture containing SLS, MNA, ethanol and water. However, when PCP was administered in ethanol only, absorption was only 1.12% of the applied dose. There were also qualitative differences among the absorption profiles for the different PCP mixtures. In contrast with the PCP results, absorption of TCB or PCB was negligible in perfused porcine skin, with only 0.14% of the applied TCB dose and 0.05% of the applied PCB dose being maximally absorbed. The low absorption levels for the PCB congeners precluded the identification of mixture component effects. These results suggest that dermal absorption estimates from a single chemical exposure may not reflect absorption seen after exposure as a chemical mixture and that absorption of both TCB and PCB are minimal in this model system. (orig.)

  14. 21 CFR 82.6 - Certifiable mixtures.

    Science.gov (United States)

    2010-04-01

    ... mixture is harmless and suitable for use therein; and (3) No diluent (except resins, natural gum, pectin... mixture is for external application to shell eggs, or for use in coloring a food specified in the...

  15. Effects of active pharmaceutical ingredients mixtures in mussel Mytilus galloprovincialis.

    Science.gov (United States)

    Gonzalez-Rey, M; Mattos, J J; Piazza, C E; Bainy, A C D; Bebianno, M J

    2014-08-01

    Active pharmaceutical ingredients (APIs) are emergent environmental contaminants widely detected in surface waters as result of incomplete waste water treatment plant (WWTP) removal processes and improper disposal. The assessment of potential effects of APIs on non-target organisms is still scarce since besides presenting multiple chemical structures, properties and modes of action, these compounds occur as complex mixtures. This study comprises a 15-day exposure of mussels Mytilus galloprovincialis to mixtures (at environmentally relevant nominal concentrations) of non-steroidal inflammatory drugs ibuprofen (IBU) and diclofenac (DCF) (250 ng L(-1) each) and selective serotonin reuptake inhibitor (SSRI) fluoxetine (FLX) (75 ng L(-1)) (MIX 1) along with the addition of classical pro-oxidant copper (Cu) (5 μg L(-1)) (MIX 2). The goals included the assessment of oxidative stress, neurotoxic and endocrine effects on this sentinel species applying both a multibiomarker and gene expression (here and later gene expression is taken as synonym to gene transcription, although it is acknowledged that it is also affected by, e.g. translation, and mRNA and protein stability) analysis approaches. The results revealed a swifter antioxidant response in digestive glands than in gills induced by MIX 1, nevertheless the presence of Cu in MIX 2 promoted a higher lipid peroxidation (LPO) induction. Neither mixture altered acetylcholinesterase (AChE) activity, while both triggered the formation of vitellogenin-like proteins in females confirming the xenoestrogenic effect of mixtures. All these results varied with respect to those obtained in previous single exposure essays. Moreover, RT-PCR analysis revealed a catalase (CAT) and CYP4Y1 gene expression down- and upregulation, respectively, with no significant changes in mRNA levels of genes encoding superoxide dismutase (SOD) and glutathione-S-transferase (GST). Finally, this study highlights variable tissue and time-specific biomarker

  16. Applied chemical engineering thermodynamics

    CERN Document Server

    Tassios, Dimitrios P

    1993-01-01

    Applied Chemical Engineering Thermodynamics provides the undergraduate and graduate student of chemical engineering with the basic knowledge, the methodology and the references he needs to apply it in industrial practice. Thus, in addition to the classical topics of the laws of thermodynamics,pure component and mixture thermodynamic properties as well as phase and chemical equilibria the reader will find: - history of thermodynamics - energy conservation - internmolecular forces and molecular thermodynamics - cubic equations of state - statistical mechanics. A great number of calculated problems with solutions and an appendix with numerous tables of numbers of practical importance are extremely helpful for applied calculations. The computer programs on the included disk help the student to become familiar with the typical methods used in industry for volumetric and vapor-liquid equilibria calculations.

  17. Potential Impacts of Spilled Hydraulic Fracturing Fluid Chemicals on Water Resources: Types, volumes, and physical-chemical properties of chemicals

    Science.gov (United States)

    Hydraulic fracturing (HF) fluid chemicals spilled on-site may impact drinking water resources. While chemicals generally make up <2% of the total injected fluid composition by mass, spills may have undiluted concentrations. HF fluids typically consist of a mixture of base flui...

  18. Strategies for Transferring Mixtures of Organic Contaminants from Aquatic Environments into Bioassays.

    Science.gov (United States)

    Jahnke, Annika; Mayer, Philipp; Schäfer, Sabine; Witt, Gesine; Haase, Nora; Escher, Beate I

    2016-06-07

    Mixtures of organic contaminants are ubiquitous in the environment. Depending on their persistence and physicochemical properties, individual chemicals that make up the mixture partition and distribute within the environment and might then jointly elicit toxicological effects. For the assessment and monitoring of such mixtures, a variety of cell-based in vitro and low-complexity in vivo bioassays based on algae, daphnids or fish embryos are available. A very important and sometimes unrecognized challenge is how to combine sampling, extraction and dosing to transfer the mixtures from the environment into bioassays, while conserving (or re-establishing) their chemical composition at adjustable levels for concentration-effect assessment. This article outlines various strategies for quantifiable transfer from environmental samples including water, sediment, and biota into bioassays using total extraction or polymer-based passive sampling combined with either solvent spiking or passive dosing.

  19. A modified UNIQUAC equation for mixtures containing self-associating compounds

    Directory of Open Access Journals (Sweden)

    P. A. Pessôa Filho

    2005-09-01

    Full Text Available The UNIQUAC model for the excess Gibbs energy is modified using chemical theory to account for chain-like association occurring in self-associating compounds such as alcohols. The equation considers the alcohol to be a mixture of clusters in chemical equilibrium. The UNIQUAC equation is used to model the behavior of the mixture of clusters, with size and surface parameters related to the number of alcohol molecules involved in their formation. The values of association enthalpy and entropy were obtained through fitting vapor pressure data. The model is used to correlate phase behavior of alcohol-hydrocarbon mixtures at low pressures, presenting excellent results in bubble point calculations. A further extension was made to allow for cross-association, the formation of a hydrogen bond between the molecules of an alcohol and an active solute. This extension was used to model alcohol-aromatic mixtures with equally good results.

  20. Fluctuating hydrodynamics of multi-species reactive mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharjee, Amit Kumar; Donev, Aleksandar [Courant Institute of Mathematical Sciences, New York University, 251 Mercer Street, New York, New York 10012 (United States); Balakrishnan, Kaushik [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, California 91109 (United States); Garcia, Alejandro L. [Department of Physics and Astronomy, San Jose State University, 1 Washington Square, San Jose, California 95192 (United States); Bell, John B. [Computational Research Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States)

    2015-06-14

    We formulate and study computationally the fluctuating compressible Navier-Stokes equations for reactive multi-species fluid mixtures. We contrast two different expressions for the covariance of the stochastic chemical production rate in the Langevin formulation of stochastic chemistry, and compare both of them to predictions of the chemical master equation for homogeneous well-mixed systems close to and far from thermodynamic equilibrium. We develop a numerical scheme for inhomogeneous reactive flows, based on our previous methods for non-reactive mixtures [Balakrishnan , Phys. Rev. E 89, 013017 (2014)]. We study the suppression of non-equilibrium long-ranged correlations of concentration fluctuations by chemical reactions, as well as the enhancement of pattern formation by spontaneous fluctuations. Good agreement with available theory demonstrates that the formulation is robust and a useful tool in the study of fluctuations in reactive multi-species fluids. At the same time, several problems with Langevin formulations of stochastic chemistry are identified, suggesting that future work should examine combining Langevin and master equation descriptions of hydrodynamic and chemical fluctuations.

  1. Concentration addition, independent action and generalized concentration addition models for mixture effect prediction of sex hormone synthesis in vitro

    DEFF Research Database (Denmark)

    Hadrup, Niels; Taxvig, Camilla; Pedersen, Mikael;

    2013-01-01

    , antagonism was observed for effects of Mixture 2 on this hormone. The mixtures contained chemicals exerting only limited maximal effects. This hampered prediction by the CA and IA models, whereas the GCA model could be used to predict a full dose response curve. Regarding effects on progesterone...

  2. Fiscal 1997 report on the results of the international standardization R and D. Measurement of ultra-micro chemical substances and measuring methods of hormone effects; 1997 nendo seika hokokusho kokusai hyojun soseigata kenkyu kaihatsu. Chobiryo kagaku busshitsu no keisoku horumon eikyo sayo sokuteiho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    Concerning the measurement system of ultra-micro hazardous chemical substances in the global environment, the paper examined the present situation of chemical substances such as dioxins, made an experimental study on the method to analyze dioxins in exhaust gas from an aspect of international consistency, and worked out a JIS draft. As to the standard measuring method of hormone effects of chemical substances, the paper developed the competitive bonding experiment system to measure bonding ability of chemical substances to homo sapiens estrogen receptor (ER). By measuring ER bonding ability of 78 kinds of chemical substances, the measuring method was developed. In the development of the assay system for detection of hormone-like compounds, the assay system with transfer activity via estrogen receptor as an index was established using cultured cells and yeast. Further, the development was made of a measuring method of receptor bonding activity of hormone-like substances. 33 refs., 151 figs., 66 tabs.

  3. Mixture toxicity of three toxicants with similar and dissimilar modes of action to Daphnia magna.

    Science.gov (United States)

    Syberg, Kristian; Elleby, Anders; Pedersen, Henrik; Cedergreen, Nina; Forbes, Valery E

    2008-03-01

    Mixture toxicity of similar- and dissimilar-acting toxicants can be predicted by the models concentration addition (CA) and independent action (IA) using single substance toxicity data. Knowledge of the toxicants mode of action is thus required in order to use the models. In order to test the predictive capability of the models, we conducted Daphnia magna 48 h immobilization experiments with three toxicants with known modes of action (dimethoate, pirimicarb and linear alkyl benzene sulfonate) singly, and in binary and ternary mixtures. Our results indicate that CA and IA predict binary mixtures of similar- and dissimilar-acting toxicants equally well. CA and IA also equally predicted the ternary mixture consisting of both similar- and dissimilar-acting chemicals. The paper discusses the concept of mode of action and the implications the definition of mode of action has on the choice of reference model for mixture toxicity studies.

  4. Combined toxicity of pesticide mixtures on green algae and photobacteria.

    Science.gov (United States)

    Liu, Shu-Shen; Wang, Cheng-Lin; Zhang, Jin; Zhu, Xiang-Wei; Li, Wei-Ying

    2013-09-01

    Different organisms have diverse responses to the same chemicals or mixtures. In this paper, we selected the green algae Chlorella pyrenoidosa (C. pyrenoidosa) and photobacteria Vibrio qinghaiensis sp.-Q67 (V. qinghaiensis) as target organisms and determined the toxicities of six pesticides, including three herbicides (simetryn, bromacil and hexazinone), two fungicides (dodine and metalaxyl) and one insecticide (propoxur), and their mixtures by using the microplate toxicity analysis. The toxicities of three herbicides to C. pyrenoidosa are much higher than those to V. qinghaiensis, and the toxicities of metalaxyl and propoxur to V. qinghaiensis are higher than those to C. pyrenoidosa, while the toxicity of dodine to C. pyrenoidosa is similar to those to V. qinghaiensis. Using the concentration addition as an additive reference model, the binary pesticide mixtures exhibited different toxicity interactions, i.e., displayed antagonism to C. pyrenoidosa but synergism to V. qinghaiensis. However, the toxicities of the multi-component mixtures of more than two components are additive and can be predicted by the concentration addition model.

  5. Shanxi Sanwei: Leading International Fine Chemical Company

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ Three big bouds Since its listing in Shenzhen Stock Exchange in 1997, Shanxi Sanwei has conducted financing in the stock market four times and raised a total of RMB1.2 billion. In 1997 around RMB320 million raised by the company in the first open circulation of its shares was used in technical renovation and capacity expansion includinga 20 000 t/a BDO project.

  6. Modeling mixtures of thyroid gland function disruptors in a vertebrate alternative model, the zebrafish eleutheroembryo

    Energy Technology Data Exchange (ETDEWEB)

    Thienpont, Benedicte; Barata, Carlos [Department of Environmental Chemistry, Institute of Environmental Assessment and Water Research (IDAEA, CSIC), Jordi Girona, 18-26, 08034 Barcelona (Spain); Raldúa, Demetrio, E-mail: drpqam@cid.csic.es [Department of Environmental Chemistry, Institute of Environmental Assessment and Water Research (IDAEA, CSIC), Jordi Girona, 18-26, 08034 Barcelona (Spain); Maladies Rares: Génétique et Métabolisme (MRGM), University of Bordeaux, EA 4576, F-33400 Talence (France)

    2013-06-01

    Maternal thyroxine (T4) plays an essential role in fetal brain development, and even mild and transitory deficits in free-T4 in pregnant women can produce irreversible neurological effects in their offspring. Women of childbearing age are daily exposed to mixtures of chemicals disrupting the thyroid gland function (TGFDs) through the diet, drinking water, air and pharmaceuticals, which has raised the highest concern for the potential additive or synergic effects on the development of mild hypothyroxinemia during early pregnancy. Recently we demonstrated that zebrafish eleutheroembryos provide a suitable alternative model for screening chemicals impairing the thyroid hormone synthesis. The present study used the intrafollicular T4-content (IT4C) of zebrafish eleutheroembryos as integrative endpoint for testing the hypotheses that the effect of mixtures of TGFDs with a similar mode of action [inhibition of thyroid peroxidase (TPO)] was well predicted by a concentration addition concept (CA) model, whereas the response addition concept (RA) model predicted better the effect of dissimilarly acting binary mixtures of TGFDs [TPO-inhibitors and sodium-iodide symporter (NIS)-inhibitors]. However, CA model provided better prediction of joint effects than RA in five out of the six tested mixtures. The exception being the mixture MMI (TPO-inhibitor)-KClO{sub 4} (NIS-inhibitor) dosed at a fixed ratio of EC{sub 10} that provided similar CA and RA predictions and hence it was difficult to get any conclusive result. There results support the phenomenological similarity criterion stating that the concept of concentration addition could be extended to mixture constituents having common apical endpoints or common adverse outcomes. - Highlights: • Potential synergic or additive effect of mixtures of chemicals on thyroid function. • Zebrafish as alternative model for testing the effect of mixtures of goitrogens. • Concentration addition seems to predict better the effect of

  7. The Kinetics of Enzyme Mixtures

    Directory of Open Access Journals (Sweden)

    Simon Brown

    2014-03-01

    Full Text Available Even purified enzyme preparations are often heterogeneous. For example, preparations of aspartate aminotransferase or cytochrome oxidase can consist of several different forms of the enzyme. For this reason we consider how different the kinetics of the reactions catalysed by a mixture of forms of an enzyme must be to provide some indication of the characteristics of the species present. Based on the standard Michaelis-Menten model, we show that if the Michaelis constants (Km of two isoforms differ by a factor of at least 20 the steady-state kinetics can be used to characterise the mixture. However, even if heterogeneity is reflected in the kinetic data, the proportions of the different forms of the enzyme cannot be estimated from the kinetic data alone. Consequently, the heterogeneity of enzyme preparations is rarely reflected in measurements of their steady-state kinetics unless the species present have significantly different kinetic properties. This has two implications: (1 it is difficult, but not impossible, to detect molecular heterogeneity using kinetic data and (2 even when it is possible, a considerable quantity of high quality data is required.

  8. Atomistic simulations of bicelle mixtures.

    Science.gov (United States)

    Jiang, Yong; Wang, Hao; Kindt, James T

    2010-06-16

    Mixtures of long- and short-tail phosphatidylcholine lipids are known to self-assemble into a variety of aggregates combining flat bilayerlike and curved micellelike features, commonly called bicelles. Atomistic simulations of bilayer ribbons and perforated bilayers containing dimyristoylphosphatidylcholine (DMPC, di-C(14) tails) and dihexanoylphosphatidylcholine (DHPC, di-C(6) tails) have been carried out to investigate the partitioning of these components between flat and curved microenvironments and the stabilization of the bilayer edge by DHPC. To approach equilibrium partitioning of lipids on an achievable simulation timescale, configuration-bias Monte Carlo mutation moves were used to allow individual lipids to change tail length within a semigrand-canonical ensemble. Since acceptance probabilities for direct transitions between DMPC and DHPC were negligible, a third component with intermediate tail length (didecanoylphosphatidylcholine, di-C(10) tails) was included at a low concentration to serve as an intermediate for transitions between DMPC and DHPC. Strong enrichment of DHPC is seen at ribbon and pore edges, with an excess linear density of approximately 3 nm(-1). The simulation model yields estimates for the onset of edge stability with increasing bilayer DHPC content between 5% and 15% DHPC at 300 K and between 7% and 17% DHPC at 323 K, higher than experimental estimates. Local structure and composition at points of close contact between pores suggest a possible mechanism for effective attractions between pores, providing a rationalization for the tendency of bicelle mixtures to aggregate into perforated vesicles and perforated sheets.

  9. Shock compression response of Ti+B reactive powder mixtures

    Science.gov (United States)

    Gonzales, M.; Gurumurthy, A.; Kennedy, G. B.; Gokhale, A. M.; Thadhani, N. N.

    2014-05-01

    The shock compression response of Ti+2B (1:2 Ti:B stoichiometric ratio) reactive powder mixtures at ~50% theoretical material density (TMD) is investigated for shock pressures up to 5 GPa to investigate the possible shock-induced chemical reactivity of this highly exothermic mixture. The shock adiabat is produced from instrumented parallel-plate gas-gun impact experiments on encapsulated powders using poly-vinylidene fluoride (PVDF) stress gauges to measure the input and propagated stresses and wave speed in the powder. The shock compression regime is probed from crush-up to full density and onward to assess the potential onset of a shock-induced chemical reaction event in the powder mixture. A series of two-dimensional continuum meso-scale simulations on validated simulated microstructures are performed to predict the shock compression response and identify the meso-scale mechanics that are essential for reaction. The suitability of the synthetic microstructural representations is evaluated by comparing the experimental and predicted pressure traces.

  10. Environment international law; Droit international de l`environnement

    Energy Technology Data Exchange (ETDEWEB)

    Lavieille, J.M.

    1998-12-31

    The characteristics of the environment international law are analyzed in a first part: nature, aim, history, stakes, sources and institutions. The content of the environment international law is analyzed in the second part: principles, conventions relative to the air, climates, marine and surface waters, soils, forests, nature conservation at a regional and global scale, chemical compounds and noxious wastes. (J.S.)

  11. Effect of Mixture Pressure and Equivalence Ratio on Detonation Cell Size for Hydrogen-Air Mixtures

    Science.gov (United States)

    2015-06-01

    EFFECT OF MIXTURE PRESSURE AND EQUIVALENCE RATIO ON DETONATION CELL SIZE FOR HYDROGEN -AIR MIXTURES...protection in the United States. AFIT-ENY-MS-15-J-045 EFFECT OF MIXTURE PRESSURE AND EQUIVALENCE RATIO ON DETONATION CELL SIZE FOR HYDROGEN -AIR...DISTRIBUTION UNLIMITED. AFIT-ENY-MS-15-J-045 EFFECT OF MIXTURE PRESSURE AND EQUIVALENCE RATIO ON DETONATION CELL SIZE FOR HYDROGEN -AIR MIXTURES

  12. Tortuous path chemical preconcentrator

    Science.gov (United States)

    Manginell, Ronald P.; Lewis, Patrick R.; Adkins, Douglas R.; Wheeler, David R.; Simonson, Robert J.

    2010-09-21

    A non-planar, tortuous path chemical preconcentrator has a high internal surface area having a heatable sorptive coating that can be used to selectively collect and concentrate one or more chemical species of interest from a fluid stream that can be rapidly released as a concentrated plug into an analytical or microanalytical chain for separation and detection. The non-planar chemical preconcentrator comprises a sorptive support structure having a tortuous flow path. The tortuosity provides repeated twists, turns, and bends to the flow, thereby increasing the interfacial contact between sample fluid stream and the sorptive material. The tortuous path also provides more opportunities for desorption and readsorption of volatile species. Further, the thermal efficiency of the tortuous path chemical preconcentrator is comparable or superior to the prior non-planar chemical preconcentrator. Finally, the tortuosity can be varied in different directions to optimize flow rates during the adsorption and desorption phases of operation of the preconcentrator.

  13. Transcriptional impact of organophosphate and metal mixtures on olfaction: Copper dominates the chlorpyrifos-induced response in adult zebrafish

    OpenAIRE

    Tilton, Fred A.; Tilton, Susan C.; Bammler, Theo K.; Beyer, Richard P; Stapleton, Patricia L.; Nathaniel L Scholz; Gallagher, Evan P.

    2011-01-01

    Chemical exposures in fish have been linked to loss of olfaction leading to an inability to detect predators and prey and decreased survival. However, the mechanisms underlying olfactory neurotoxicity are not well characterized, especially in environmental exposures which involve chemical mixtures. We used zebrafish to characterize olfactory transcriptional responses by two model olfactory inhibitors, the pesticide chlorpyrifos (CPF) and mixtures of CPF with the neurotoxic metal copper (Cu). ...

  14. Ultrasonic study on organic liquid and binary organic liquid mixtures by using Schaaffs' collision factor theory

    Institute of Scientific and Technical Information of China (English)

    Lu Yi-Gang; Dong Yan-Wu

    2006-01-01

    Based on Schaaff's collision factor theory (CFT) in liquids, the equations for nonlinear ultrasonic parameters in both organic liquid and binary organic liquid mixtures are deduced. The nonlinear ultrasonic parameters, including pressure coefficient, temperature coefficients of ultrasonic velocity, and nonlinear acoustic parameter B/A in both organic liquid and binary organic liquid mixtures, are evaluated for comparison with the measured results and data from other sources. The equations show that the coefficient of ultrasonic velocity and nonlinear acoustic parameter B/A are closely related to molecular interactions. These nonlinear ultrasonic parameters reflect some information of internal structure and outside status of the medium or mixtures. From the exponent of repulsive forces of the molecules,several thermodynamic parameters, pressure and temperature of the medium, the nonlinear ultrasonic parameters and ultrasonic nature of the medium can be evaluated. When evaluating and studying nonlinear acoustic parameter B/A of binary organic liquid mixtures, there is no need to know the nonlinear acoustic parameter B/A of the components.Obviously, the equation reveals the connection between the nonlinear ultrasonic nature and internal structure and outside status of the mixtures more directly and distinctly than traditional mixture law for B/A, e.g. Apfel's and Sehgal's laws for liquid binary mixtures.

  15. Internal and International Corruption

    Directory of Open Access Journals (Sweden)

    Dr.Sc. Mario Antinucci

    2015-06-01

    Full Text Available This subject, whence the name of this paper originates from, must be addressed with courage and intellectual integrity by all of us, the different parts of the civil society, the public institutions, the entrepreneurs and the legal professionals, the youth and the new generations. All the public policies of the European governments share the belief of a direct correlation between the criminal density connected to corruption of States political and economic protagonists and the lack of availability of investments on young talents, new generations, both in the entrepreneurial and in the professional fields. In most Member States, anticorruption policies have gained an increased prominence in government agendas and the financial crisis has drawn attention to the integrity and accountability of policy-makers. Most Member States that are currently in serious financial difficulties have acknowledged the seriousness of issues related to corruption and have created (or are planning anticorruption programs in order to deal with the risks deriving from this issue and with the diversion of public funds. In some Member States, the economic adjustment programs provide for explicit obligations related to anti-corruption policies. Even when not formally connected to adjustment programs, anticorruption policies complement the adjustment measures, especially in those countries in which corruption is a serious issue.  During the European Semester of economic policy coordination, recommendations for efficiently fighting corruption have been laid out; Among the most vulnerable sectors, urban development and building projects are certainly very exposed to corruption risks and to infiltration of internal and transnational organized crime.

  16. Thermodynamics of organic mixtures containing amines. VIII. Systems with quinoline

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, Juan Antonio [G.E.T.E.F., Grupo Especializado en Termodinamica de Equilibrio entre Fases, Departamento de Fisica Aplicada, Facultad de Ciencias, Universidad de Valladolid, E-47071 Valladolid (Spain)], E-mail: jagl@termo.uva.es; Domanska, Urszula; Zawadzki, Maciej [Physical Chemistry Division, Faculty of Chemistry, Warsaw University of Technology, 00-664 Warsaw (Poland)

    2008-08-15

    (Solid + liquid) equilibrium temperatures for mixtures containing quinoline and 1-dodecanol, 1-hexadecanol, or 1-octadecanol have been measured using a dynamic method. (Quinoline + benzene, +alkane, or +1-alkanol) systems were investigated using DISQUAC. The corresponding interaction parameters are reported. The model yields a good representation of molar excess Gibbs free energies, G{sup E}, molar excess enthalpies, H{sup E}, and of the (solid + liquid) equilibria, SLE. Interactional and structural effects were analysed comparing H{sup E} and the molar excess internal energy at constant volume, U{sub V}{sup E}. It was encountered that structural effects are very important in systems involving alkanes or 1-alkanols. Interactions between amine molecules are stronger in mixtures with quinoline than in those containing pyridine, which was ascribed to the higher polarizability of quinoline.

  17. Modelagem dos processos químicos em plasmas de misturas gasosas usadas na corrosão de silício. Parte 2: SF6 / O2 Modeling of the chemical processes in the plasma of gaseous mixtures used in the etching of silicon. Part 2: SF6 / O2

    Directory of Open Access Journals (Sweden)

    G. F. Bauerfeldt

    1998-02-01

    Full Text Available In this work, a numerical modeling analysis of the gas-phase decomposition of SF6 / O2 mixtures, in the presence of silicon, was performed. The relative importance of individual processes and the effect of the parameters' uncertainties were determined. The model was compared with experimental data for the plasma etching of silicon and with the calculated results for the CF4 / O2 system. In both systems the main etching agent is the fluorine atom and the concentration of the major species depends on the composition of the mixture. The etching rate is greater for SF6 / O2.

  18. The Hamilton principle for fluid binary mixtures with two temperatures

    CERN Document Server

    Gouin, Henri

    2009-01-01

    For binary mixtures of fluids without chemical reactions, but with components having different temperatures, the Hamilton principle of least action is able to produce the equation of motion for each component and a balance equation of the total heat exchange between components. In this nonconservative case, a Gibbs dynamical identity connecting the equations of momenta, masses, energy and heat exchange allows to deduce the balance equation of energy of the mixture. Due to the unknown exchange of heat between components, the number of obtained equations is less than the number of field variables. The second law of thermodynamics constrains the possible expression of a supplementary constitutive equation closing the system of equations. The exchange of energy between components produces an increasing rate of entropy and creates a dynamical pressure term associated with the difference of temperature between components. This new dynamical pressure term fits with the results obtained by classical thermodynamical a...

  19. Ionic liquids for separation of olefin-paraffin mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Sheng; Luo, Huimin; Huang, Jing-Fang

    2014-07-15

    The invention is directed to an ionic liquid comprising (i) a cationic portion containing a complex of a silver (I) ion and one or more neutral ligands selected from organoamides, organoamines, olefins, and organonitriles, and (ii) an anionic portion having the chemical formula ##STR00001## wherein m and n are independently 0 or an integer of 1 or above, and p is 0 or 1, provided that when p is 0, the group --N--SO.sub.2--(CF.sub.2).sub.nCF.sub.3 subtended by p is replaced with an oxide atom connected to the shown sulfur atom. The invention is also directed to a method for separating an olefin from an olefin-paraffin mixture by passing the mixture through a layer of the ionic liquid described above.

  20. An integral equation model for warm and hot dense mixtures

    CERN Document Server

    Starrett, C E; Daligault, J; Hamel, S

    2014-01-01

    In Starrett and Saumon [Phys. Rev. E 87, 013104 (2013)] a model for the calculation of electronic and ionic structures of warm and hot dense matter was described and validated. In that model the electronic structure of one "atom" in a plasma is determined using a density functional theory based average-atom (AA) model, and the ionic structure is determined by coupling the AA model to integral equations governing the fluid structure. That model was for plasmas with one nuclear species only. Here we extend it to treat plasmas with many nuclear species, i.e. mixtures, and apply it to a carbon-hydrogen mixture relevant to inertial confinement fusion experiments. Comparison of the predicted electronic and ionic structures with orbital-free and Kohn-Sham molecular dynamics simulations reveals excellent agreement wherever chemical bonding is not significant.

  1. Synthesis of Copper Nanoparticles Using Mixture of Allylamine and Polyallylamine

    Directory of Open Access Journals (Sweden)

    Rubén Sierra-Ávila

    2015-01-01

    Full Text Available Copper nanoparticles (Cu-NPs with sizes lower than 31 nm were prepared by wet chemical reduction using copper sulfate solution, hydrazine, and mixture of allylamine (AAm and polyallylamine (PAAm as stabilizing agents. The use of AAm/PAAm mixture leads to the formation of Cu and CuO nanoparticles. The resulting nanostructures were characterized by XRD, TGA, and TEM. The average particle diameters were determined by the Debye-Scherrer equation. Analysis by TGA, TEM, GS-MS, and 1HNMR reveals that synthesized NPs with AAm presented a coating with similar characteristics to NPs with PAAm, suggesting that AAm underwent polymerization during the synthesis. The synthesis of NPs using AAm could be a good alternative to reduce production costs.

  2. Differential effects of a complex organochlorine mixture on the proliferation of breast cancer cell lines

    Energy Technology Data Exchange (ETDEWEB)

    Aube, Michel, E-mail: 4aubem@videotron.ca [Axe de recherche en sante des populations et environnementale, Centre de recherche du Centre hospitalier universitaire de Quebec and Universite Laval, 2875 Boulevard Laurier, Edifice Delta 2, bureau 600, Quebec, QC, Canada G1V 2M2 (Canada); Larochelle, Christian, E-mail: christian.larochelle@inspq.qc.ca [Axe de recherche en sante des populations et environnementale, Centre de recherche du Centre hospitalier universitaire de Quebec and Universite Laval, 2875 Boulevard Laurier, Edifice Delta 2, bureau 600, Quebec, QC, Canada G1V 2M2 (Canada); Ayotte, Pierre, E-mail: pierre.ayotte@inspq.qc.ca [Axe de recherche en sante des populations et environnementale, Centre de recherche du Centre hospitalier universitaire de Quebec and Universite Laval, 2875 Boulevard Laurier, Edifice Delta 2, bureau 600, Quebec, QC, Canada G1V 2M2 (Canada); Laboratoire de Toxicologie, Institut national de sante publique du Quebec, 945 avenue Wolfe, Quebec, QC, Canada G1V 5B3 (Canada)

    2011-04-15

    Organochlorine compounds (OCs) are a group of persistent chemicals that accumulate in fatty tissues with age. Although OCs has been tested individually for their capacity to induce breast cancer cell proliferation, few studies examined the effect of complex mixtures that comprise compounds frequently detected in the serum of women. We constituted such an OC mixture containing 15 different components in environmentally relevant proportions and assessed its proliferative effects in four breast cancer cell lines (MCF-7, T47D, CAMA-1, MDAMB231) and in non-cancerous CV-1 cells. We also determined the capacity of the mixture to modulate cell cycle stage of breast cancer cells and to induce estrogenic and antiandrogenic effects using gene reporter assays. We observed that low concentrations of the mixture (100x10{sup 3} and 50x10{sup 3} dilutions) stimulated the proliferation of MCF-7 cells while higher concentrations (10x10{sup 3} and 5x10{sup 3} dilutions) had the opposite effect. In contrast, the mixture inhibited the proliferation of non-hormone-dependent cell lines. The mixture significantly increased the number of MCF-7 cells entering the S phase, an effect that was blocked by the antiestrogen ICI 182,780. Low concentrations of the mixture also caused an increase in CAMA-1 cell proliferation but only in the presence estradiol and dihydrotestosterone (p<0.05 at the 50x10{sup 3} dilution). DDT analogs and polychlorinated biphenyls all had the capacity to stimulate the proliferation of CAMA-1 cells in the presence of sex steroids. Reporter gene assays further revealed that the mixture and several of its constituents (DDT analogs, aldrin, dieldrin, {beta}-hexachlorocyclohexane, toxaphene) induced estrogenic effects, whereas the mixture and several components (DDT analogs, aldrin, dieldrin and PCBs) inhibited the androgen signaling pathway. Our results indicate that the complex OC mixture increases the proliferation of MCF-7 cells due to its estrogenic potential. The

  3. Afrikaner spirituality: A complex mixture

    Directory of Open Access Journals (Sweden)

    Erna Olivier

    2006-10-01

    Full Text Available The article argues that the perception that Afrikaner spirituality is and has always been founded mainly or only upon the Calvinistic tradition is a misconception. Nineteenth century Afrikaner spiritualism consisted of a mixture of theology, philosophy and a way of adapting to extreme living conditions. These factors, although with different contents, are also the determinant issues that made 21st century Afrikaner spirituality such a complex phenomenon. The article postulates that the Afrikaner nation’s current identity crisis can be resolved by closely looking at the different influences on the spirituality of the nation and by carefully guiding the people through the complex set of multiple choices to a fresh relation with Christ in a new found Christian identity to confirm our Christian foundation.

  4. Investigating swelling characteristics of mixtures for buffer materials by an improved arrangement

    Energy Technology Data Exchange (ETDEWEB)

    Ning-chien, Tung; Yi-lin, Jane [Ching Yun Univ., Dept. of Civil Engineering, Taiwan (China)

    2005-07-01

    The existence of Swelling Clay usually increases the difficulties in engineer base construction and safety, which gives a big challenge to civil engineers. The resulting problems include: effect of road surface obstruction and base structure destruction. Nevertheless, in some aspects, the swelling potential of the clay is still needed in order to utilize certain water absorption and retraction characteristics, so that the base structure has the ability to self-heal and to avoid expansion of structure gaps. Therefore, during the choice of materials, there is a requirement to evaluate the magnitude of the swelling force, in order to determine the needs for the engineering. Based on the sketch of swelling-force measurement suggested in International Journal of Rock Mechanics and Mining Science, Madsen (1999), a new set of equipment is designed to measure two characteristics of soil, swelling potential and swelling force, simultaneously. Meantime, the integration of a user friendly computer program equipped with multi-functions such as data retrieving, data analyzing and graphic plotting makes this equipment a completely automatic and precise measuring system. In the experiment, the swelling characteristics of various composite ratios of bentonite/ laterite/quartz sand mixtures were investigated to measure both swelling potential and force. The swelling force decrease by adding laterite and quartz sand to bentonite. And, this mixture could also satisfy the needs of the physical and chemical characteristics for buffer materials. Whereas this experiment is able to measure the swelling stress and strain directly, it could save time for 50 percent in comparison with the method mentioned in USBR-5707-89. The application of this equipment can decrease the usage of labor and man-made errors in a considerable amount, which will be a great help to research as well as practical purposes. In the fields of environmental and civil engineering, such invention also offers the

  5. CONSOLIDATION AND COMPACTION OF POWDER MIXTURES .1. BINARY-MIXTURES OF SAME PARTICLE-SIZE FRACTIONS OF DIFFERENT TYPES OF CRYSTALLINE LACTOSE

    NARCIS (Netherlands)

    RIEPMA, KA; LERK, CF; DEBOER, AH; BOLHUIS, GK; KUSSENDRAGER, KD

    1990-01-01

    Binary powder mixtures of four different types of crystalline lactose: alpha-lactose monohydrate, anhydrous alpha-lactose, roller-dried beta-lactose and crystalline beta-lactose, were compressed into tablets. The results showed a proportional intercorrelation of the crushing strength and internal sp

  6. Holographic Superfluidity in Imbalanced Mixtures

    CERN Document Server

    Erdmenger, Johanna; Kerner, Patrick; Ngo, Thanh Hai

    2011-01-01

    We construct superfluid black hole solutions with two chemical potentials. By analogy with QCD, the two chemical potentials correspond to the baryon and isospin symmetries, respectively. We consider two systems: the back-reacted U(2) Einstein-Yang-Mills theory in 4+1 dimensions and the 9+1-dimensional D3/D7 brane setup with two coincident D7-brane probes. In the D7-brane model, the identification of baryon and isospin chemical potential is explicit since the dual field theory is explicitly known. Studying the phase diagram, we find in both systems a quantum phase transition at a critical ratio of the two chemical potentials. However the quantum phase transition is different in the two systems: In the D3/D7 brane setup we always find a second order phase transition, while in the Einstein-Yang-Mills theory, depending on the strength of the back-reaction, we obtain a continuous or first order transition. We expect the continuous quantum phase transition to be BKT-like. We comment on the origin of this differing ...

  7. Toxicity of four antifouling biocides and their mixtures on the brine shrimp Artemia salina.

    Science.gov (United States)

    Koutsaftis, A; Aoyama, I

    2007-11-15

    Zinc pyrithione (ZPT), Copper pyrihione (CPT), Chlorothalonil and Diuron are four of the most widely used as alternative to tributlytin (TBT) antifouling biocides in boat paints. As most previous laboratory bioassays for these biocides have been conducted solely based on acute tests with a single compound, information on the possible combined toxicity of these common biocides to marine organisms are limited. In this study, the toxicity of binary (in several proportions), ternary and quaternary mixtures were evaluated using the brine shrimp Artemia salina as test organism. Mixture toxicities were studied using the concentration addition model (isobolograms and toxic unit summation), and the mixture toxicity index (MTI). The ZPT-CPT combination had a strictly synergistic effect which requires attention because the coexistence of ZPT and CPT in the marine environment, due to transchelation of ZPT, may occur. The binary mixtures of Diuron with the metal pyrithiones exhibited various interactive effects (synergistic, antagonistic or additive) depending on concentration ratios, whereas all binary mixtures that contained Chlorothalonil exhibited antagonistic effects. The different types of combined effects subsequent to proportion variation of binary mixtures underline the importance of the combined toxicity characterization for various ratios of concentrations. The four ternary mixtures tested, also exhibited various interactive effects, and the quaternary mixture exhibited synergism. The models applied were in agreement in most cases. The observed synergistic interactions underline the requirement to review water quality guidelines, which are likely underestimating the adverse combined effects of these chemicals.

  8. Shear Strength Characteristics of Coir Fibre Stabilised Stone Matrix Asphalt Mixtures

    Directory of Open Access Journals (Sweden)

    Bindu S

    2015-09-01

    Full Text Available The triaxial test measures the mix stability in the form of shear strength and gave better information for the prediction of field performance. The stresses acting on the laboratory specimen during the test simulate the state of stresses existing in the pavement. The Stone Matrix Asphalt mixtures (SMAwere investigated using triaxial shear strength testing at 50.8 mm/min ram rate loading at 60°C to investigate the effect of additive, coir fibre on the strength properties by varying  the percentages of fibre. SMA without fibre  is taken as the control mixture. The test was conducted at 0, 50, 75 and 100kPa confinements. The Mohr-Coulomb failure theory was used to analyze the test data and the analysis shows that the SMA stabilized mixtures had highest cohesion and shear strength as compared to the control mixture, but almost similar angle of internal friction value. The higher values of cohesion and shear strength can be associated to a fibre content of 0.3% and the percentage increase in cohesion is about 53% with respect to the control mixture. This shows that the mixture has greater resistance to shearing stresses than the control mixture. There is a trend that the strain at failure increases with increasing confinement pressure, indicating their stress dependent behaviour. The stress-strain curves indicate that the peak stress developed and the time of its occurrence is higher in stabilized mixtures when compared to those of the control mixture. For stabilized mixtures, it is observed that the shape change of the stress-strain curves is more gradual with increase in fibre content and brittle type failure does not seem to occur as in the case of control mixture.

  9. Enantiomer Identification in Chiral Mixtures with Broadband Microwave Spectroscopy

    Science.gov (United States)

    Shubert, V. Alvin; Schmitz, David; Medcraft, Chris; Patterson, David; Doyle, John M.; Schnell, Melanie

    2014-06-01

    In nature and as products of chemical syntheses, chiral molecules often exist in mixtures with other chiral molecules. The analysis of these complex mixtures to identify the components, determine which enantiomers are present, and to measure the enantiomeric excesses (ee) is still one of the challenging but very important tasks of analytical chemistry. These analyses are required at every step of modern drug development, from candidate searches to production and regulation. We present here a new method of identifying individual enantiomers in mixtures of chiral molecules in the gas phase. It is based on broadband rotational spectroscopy and employs a sum or difference frequency generation three-wave mixing process that involves a closed cycle of three rotational transitions. The phase of the acquired signal bares the signature of the enantiomer (see figure), as it depends upon the combined quantity, μaμbμc, which is of opposite sign between members of an enantiomeric pair. Furthermore, because the signal amplitude is proportional to the ee, this technique allows for both determining which enantiomer is in excess and by how much. The high resolution of our technique allows us to perform molecule specific measurements of mixtures of chiral molecules with μaμbμc ≠ 0, even when the molecules are very similar (e.g. conformational isomers). We introduce the technique and present results on the analysis of mixtures of the terpenes, carvone, menthone, and carvomenthenol. D. Patterson, M. Schnell, J. M. Doyle, Nature. 497, 475-477, 2013 V. A. Shubert, D. Schmitz, D. Patterson, J. M. Doyle, M. Schnell, Ang. Chem. Int. Ed. 53, 1152-1155,2014

  10. Linking in Vitro Effects and Detected Organic Micropollutants in Surface Water Using Mixture-Toxicity Modeling.

    Science.gov (United States)

    Neale, Peta A; Ait-Aissa, Selim; Brack, Werner; Creusot, Nicolas; Denison, Michael S; Deutschmann, Björn; Hilscherová, Klára; Hollert, Henner; Krauss, Martin; Novák, Jiří; Schulze, Tobias; Seiler, Thomas-Benjamin; Serra, Helene; Shao, Ying; Escher, Beate I

    2015-12-15

    Surface water can contain countless organic micropollutants, and targeted chemical analysis alone may only detect a small fraction of the chemicals present. Consequently, bioanalytical tools can be applied complementary to chemical analysis to detect the effects of complex chemical mixtures. In this study, bioassays indicative of activation of the aryl hydrocarbon receptor (AhR), activation of the pregnane X receptor (PXR), activation of the estrogen receptor (ER), adaptive stress responses to oxidative stress (Nrf2), genotoxicity (p53) and inflammation (NF-κB) and the fish embryo toxicity test were applied along with chemical analysis to water extracts from the Danube River. Mixture-toxicity modeling was applied to determine the contribution of detected chemicals to the biological effect. Effect concentrations for between 0 to 13 detected chemicals could be found in the literature for the different bioassays. Detected chemicals explained less than 0.2% of the biological effect in the PXR activation, adaptive stress response, and fish embryo toxicity assays, while five chemicals explained up to 80% of ER activation, and three chemicals explained up to 71% of AhR activation. This study highlights the importance of fingerprinting the effects of detected chemicals.

  11. A numerical analysis of the effects of a stratified pre-mixture on homogeneous charge compression ignition combustion

    Energy Technology Data Exchange (ETDEWEB)

    Jamsran, Narankhuu; Lim, Ock Taeck [University of Ulsan, Ulsan (Korea, Republic of)

    2012-06-15

    We investigated the efficacy of fuel stratification in a pre-mixture of dimethyl ether (DME) and n-butane, which have different autoignition characteristics, for reducing the pressure rise rate (PRR) of homogeneous charge compression ignition engines. A new chemical reaction model was created by mixing DME and n-butane and compared with existing chemical reaction models to verify the effects observed. The maximum PRR depended on the mixture ratio. When DME was charged with stratification and n-butane was charged with homogeneity, the maximum PRR was the lowest among all the mixtures studied. Calculations were performed using CHEMKIN and modified using SENKIN software.

  12. Desempenho da mistura forrageira de aveia-preta mais azevém e atributos químicos do solo em função da aplicação de esterco líquido de suínos Performance of at and italian rye-grass mixture and soil chemical attributes as related to liquid swine manure application

    Directory of Open Access Journals (Sweden)

    Tangriani Simioni Assmann

    2007-12-01

    Full Text Available A produção de matéria seca de pastagens anuais de inverno normalmente é baixa em virtude da limitação de nutrientes disponíveis no solo, a qual pode ser corrigida com o uso de esterco líquido de suínos (ELS. Realizou-se um experimento, de maio a novembro de 2003, visando avaliar a eficiência do esterco líquido de suínos sobre a produção de matéria seca e N-cobertura vegetal da mistura de aveia e azevém, bem como sobre alguns atributos químicos de um Latossolo Vermelho distroférrico, nas camadas de 0-5, 5-10 e 10-20 cm. O delineamento experimental foi o de blocos ao acaso, com quatro repetições, sendo constituído por quatro tratamentos, 0, 20, 40 e 80 m³ ha-1 de ELS, aplicados aos 48 e aos 116 dias após emergência das culturas. A aplicação de 80 m³ ha-1 resultou em aumento de 34 % de matéria seca acumulada em relação à testemunha. À medida que as doses de ELS foram aplicadas, houve aumento dos teores de N mineral apenas na camada de solo de 0-5 cm de profundidade. A aplicação de ELS influenciou o aumento dos teores de K no solo apenas na camada de 0-5 cm de profundidade e provocou aumento no pH e diminuição do Al3+ trocável até 20 cm de profundidade. Houve aumento na quantidade de N na cobertura vegetal conforme as doses de ELS aplicadas, com acréscimo de 0,09 mg dm-3 para cada m³ de ELS aplicado.Dry matter production of winter annual pastures is usually low due to the limited soil nutrient availability, which can be amended by the use of liquid swine manure (LSM. This experiment, carried out from May to November 2003, aimed to evaluate the efficiency of LSM in the production and accumulation of dry matter, and N-leaf concentration of an oat/Italian rye grass mixture, as well as the effect on some chemical attributes of an Oxisol in the soil layers 0-5, 5-10 and 10-20 cm soil layers. The experiment was arranged in a complete randomized block design with four replications. The treatments were four LSM doses

  13. Stability assessment of gas mixtures containing terpenes at nominal 5 nmol/mol contained in treated aluminum gas cylinders.

    Science.gov (United States)

    Rhoderick, George C

    2010-10-01

    Studies of climate change increasingly recognize the diverse influences exerted by terpenes in the atmosphere, including roles in particulates, ozone formation, and their oxidizing potential. Measurements of key terpenes suggest atmospheric concentrations ranging from low pmol/mol (parts per trillion) to nmol/mol (parts per billion), depending on location and compound. To accurately establish concentration trends, assess the role of terpenes in atmospheric chemistry, and relate measurement records from many laboratories and researchers, it is essential to have good calibration standards. The feasibility of preparing well-characterized, stable gas cylinder standards for terpenes at the nmol/mol level is not yet well established. Several of the world's National Metrology Institutes (NMIs) are researching the feasibility of developing primary and secondary reference gas standards at the nmol/mol level for terpenes. The US NMI, the National Institute of Standards and Technology, has prepared several nmol/mol mixtures, in treated aluminum gas cylinders, containing terpenes in dry nitrogen at nominal 5 nmol/mol for stability studies. Overall, 11 terpenes were studied for stability. An initial gas mixture containing nine terpenes, one oxygenate, and six aromatic compounds, including benzene as an internal standard, was prepared. Results for four of the nine terpenes in this initial mixture indicate stability in these treated aluminum gas cylinders for over 6 months and project long term (years) stability. Interesting results were seen for beta-pinene, which when using a linear equation rate decline predicts that it will reach a zero concentration level at day 416. At the same time, increases in alpha-pinene, D: -limonene (R-(+)-limonene), and p-cymene were observed, including camphene, a terpene not prepared in the gas mixture, indicating a chemical transformation of beta-pinene to these species. Additional mixtures containing combination of either alpha-pinene, camphor

  14. International Relations:

    DEFF Research Database (Denmark)

    This is the textbook for the Open University module International Relations: Continuity and Change in Global Politics. Instead of leading with a succession of theoretical 'isms', the module structures its presentation of the subject around six teaching ‘blocks’, each of which explores a dilemma......, or dimension of variation. The dilemmas in question were chosen for the way they capture key themes in the field of International Studies (IR) as well as central aspects of the ‘international’ itself (ir). The six Blocks are: • Block 1: Co-operation or conflict? Introducing international relations • Block 2......: Flat or uneven? Change and transformation in the international system • Block 3: Just or unjust? Intervention and inequality in the international system • Block 4: Top-down or bottom-up? Governance in the international system • Block 5: Secure or insecure? Pursuing security in the international system...

  15. Shear viscosity of liquid mixtures Mass dependence

    CERN Document Server

    Kaushal, R

    2002-01-01

    Expressions for zeroth, second, and fourth sum rules of transverse stress autocorrelation function of two component fluid have been derived. These sum rules and Mori's memory function formalism have been used to study shear viscosity of Ar-Kr and isotopic mixtures. It has been found that theoretical result is in good agreement with the computer simulation result for the Ar-Kr mixture. The mass dependence of shear viscosity for different mole fraction shows that deviation from ideal linear model comes even from mass difference in two species of fluid mixture. At higher mass ratio shear viscosity of mixture is not explained by any of the emperical model.

  16. Single and mixture toxicity of pharmaceuticals and chlorophenols to freshwater algae Chlorella vulgaris.

    Science.gov (United States)

    Geiger, Elisabeth; Hornek-Gausterer, Romana; Saçan, Melek Türker

    2016-07-01

    Organisms in the aquatic environment are exposed to a variety of substances of numerous chemical classes. The unintentional co-occurrence of pharmaceuticals and other contaminants of emerging concern may pose risk to non-target organisms. In this study, individual and binary mixture toxicity experiments of selected pharmaceuticals (ibuprofen and ciprofloxacin) and chlorophenols (2.4-dichlorophenol (2,4-DCP) and 3-chlorophenol (3-CP)) have been performed with freshwater algae Chlorella vulgaris. All experiments have been carried out according to the 96-h algal growth inhibition test OECD No. 201. Binary mixture tests were conducted using proportions of the respective IC50s in terms of toxic unit (TU). The mixture concentration-response curve was compared to predicted effects based on both the concentration addition (CA) and the independent action (IA) model. Additionally, the Combination Index (CI)-isobologram equation method was used to assess toxicological interactions of the binary mixtures. All substances individually tested had a significant effect on C. vulgaris population density and revealed IC50 values ciprofloxacin>3-CP>ibuprofen. Generally, it can be concluded from this study that toxic mixture effects of all tested chemicals to C. vulgaris are higher than the individual effect of each mixture component. It could be demonstrated that IC50 values of the tested mixtures predominately lead to additive effects. The CA model is appropriate to estimate mixture toxicity, while the IA model tends to underestimate the joint effect. The CI-isobologram equation method predicted the mixtures accurately and elicited synergism at low effect levels for the majority of tested combinations.

  17. Vitellogenin induction by a mixture of steroidal estrogens in freshwater fishes and relevant risk assessment.

    Science.gov (United States)

    Zhang, Hui; Kong, Fan-Xiang; Wang, Shi-He; Yu, Yang; Zhang, Min

    2009-10-01

    The study method on combined effects of environmental contaminant mixture and ecological risk assessment was discussed. Batch tests were conducted to assess the in vivo potency of binary mixtures of estrogens using plasma vitellogenin concentrations in male crucian carp as the endpoint. The estrogenic potencies of 17beta-estradiol (E(2)) and 17alpha-ethynylestradiol (EE(2)) were determined following 14 day exposure to the individual chemicals and equipotent binary mixtures. A Nonlinear regression was obtained and 95% confidence limits of effect concentration were achieved using the bootstrap method. Concentration-response curve for fixed ratio binary mixtures of E(2) and EE(2) was compared with those for individual chemicals, using the biomathematical models of concentration addition (CA) and independent action (IA). A complete overlap was found for the CA predictions with the 95% confidence interval of the best-fit regression line of the observed responses, and the IA predictions was shown lower than the observations. The observed mixture effects were considerably higher than those of the hormone alone and far exceeded the 95% confidence interval of the estrogen regression lines. The predicted effects of binary mixtures at different mixture ratios indicated that the potential impact of components on mixture would depend predominantly on its concentration, the mixture ratio and its relative potency. Results suggested that E(2) and EE(2) acted together in an additive manner and the combined effects can be accurately predicted in whole range of exposure concentration by the models of CA and IA, the model of CA might be realistic, but more useful for ecological risk assessment.

  18. Simulation of mixture microstructures via particle packing models and their direct comparison with real mixtures

    Science.gov (United States)

    Gulliver, Eric A.

    The objective of this thesis to identify and develop techniques providing direct comparison between simulated and real packed particle mixture microstructures containing submicron-sized particles. This entailed devising techniques for simulating powder mixtures, producing real mixtures with known powder characteristics, sectioning real mixtures, interrogating mixture cross-sections, evaluating and quantifying the mixture interrogation process and for comparing interrogation results between mixtures. A drop and roll-type particle-packing model was used to generate simulations of random mixtures. The simulated mixtures were then evaluated to establish that they were not segregated and free from gross defects. A powder processing protocol was established to provide real mixtures for direct comparison and for use in evaluating the simulation. The powder processing protocol was designed to minimize differences between measured particle size distributions and the particle size distributions in the mixture. A sectioning technique was developed that was capable of producing distortion free cross-sections of fine scale particulate mixtures. Tessellation analysis was used to interrogate mixture cross sections and statistical quality control charts were used to evaluate different types of tessellation analysis and to establish the importance of differences between simulated and real mixtures. The particle-packing program generated crescent shaped pores below large particles but realistic looking mixture microstructures otherwise. Focused ion beam milling was the only technique capable of sectioning particle compacts in a manner suitable for stereological analysis. Johnson-Mehl and Voronoi tessellation of the same cross-sections produced tessellation tiles with different the-area populations. Control charts analysis showed Johnson-Mehl tessellation measurements are superior to Voronoi tessellation measurements for detecting variations in mixture microstructure, such as altered

  19. Thermodynamics of mixtures containing amines

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, Juan Antonio [G.E.T.E.F. Dpto Termodinamica y Fisica Aplicada, Facultad de Ciencias, Universidad de Valladolid, Valladolid 47071 (Spain)], E-mail: jagl@termo.uva.es; Mozo, Ismael; Garcia de la Fuente, Isaias; Cobos, Jose Carlos [G.E.T.E.F. Dpto Termodinamica y Fisica Aplicada, Facultad de Ciencias, Universidad de Valladolid, Valladolid 47071 (Spain); Riesco, Nicolas [Department of Chemical Engineering, Loughborough University, Loughborough, LE113TU Leicestershire (United Kingdom)

    2008-01-30

    Mixtures with dimethyl or trimethylpyridines and alkane, aromatic compound or 1-alkanol have been examined using different theories: DISQUAC, Flory, the concentration-concentration structure factor, S{sub CC}(0), or the Kirkwood-Buff formalism. DISQUAC represents fairly well the available experimental data, and improves theoretical calculations from Dortmund UNIFAC. Two important effects have been investigated: (i) the effect of increasing the number of methyl groups attached to the aromatic ring of the amine; (ii) the effect of modifying the position of the methyl groups in this ring. The molar excess enthalpy, H{sup E}, and the molar excess volume, V{sup E}, decrease in systems with alkane or methanol as follows: pyridine > 3-methylpyridine > 3,5-dimethylpyridine and pyridine > 2-methylpyridine > 2,4-dimethylpyridine > 2,4,6-trimethylpyridine, which has been attributed to a weakening of the amine-amine interactions in the same sequences. This is in agreement with the relative variation of the effective dipole moment, {mu}-bar, and of the differences between the boiling temperature of a pyridine base and that of the homomorphic alkane. For heptane solutions, the observed H{sup E} variation, H{sup E} (3,5-dimethylpyridine) > H{sup E} (2,4-dimethylpyridine) > H{sup E} (2,6-dimethylpyridine), is explained similarly. Calculations on the basis of the Flory model confirm that orientational effects become weaker in systems with alkane in the order: pyridine > methylpyridine > dimethylpyridine > trimethylpyridine. S{sub CC}(0) calculations show that steric effects increase with the number of CH{sub 3}- groups in the pyridine base, and that the steric effects exerted by methyl groups in positions 2 and 6 are higher than when they are placed in positions 3 and 5. The hydrogen bond energy in methanol mixtures is independent of the pyridine base, and it is estimated to be -35.2 kJ mol{sup -1}. Heterocoordination in these solutions is due in part to size effects. Their

  20. 40 CFR 799.5085 - Chemical testing requirements for certain high production volume chemicals.

    Science.gov (United States)

    2010-07-01

    ... (preferred species), rat, or Chinese hamster): 40 CFR 799.9538 OR Mammalian Erythrocyte Micronucleus Test (in... CHEMICAL SUBSTANCE AND MIXTURE TESTING REQUIREMENTS Multichemical Test Rules § 799.5085 Chemical testing... paragraph (j) of this section at any time from April 17, 2006 to the end of the test data...

  1. Additivity and Interactions in Ecotoxicity of Pollutant Mixtures: Some Patterns, Conclusions, and Open Questions

    Directory of Open Access Journals (Sweden)

    Ismael Rodea-Palomares

    2015-09-01

    Full Text Available Understanding the effects of exposure to chemical mixtures is a common goal of pharmacology and ecotoxicology. In risk assessment-oriented ecotoxicology, defining the scope of application of additivity models has received utmost attention in the last 20 years, since they potentially allow one to predict the effect of any chemical mixture relying on individual chemical information only. The gold standard for additivity in ecotoxicology has demonstrated to be Loewe additivity which originated the so-called Concentration Addition (CA additivity model. In pharmacology, the search for interactions or deviations from additivity (synergism and antagonism has similarly captured the attention of researchers over the last 20 years and has resulted in the definition and application of the Combination Index (CI Theorem. CI is based on Loewe additivity, but focused on the identification and quantification of synergism and antagonism. Despite additive models demonstrating a surprisingly good predictive power in chemical mixture risk assessment, concerns still exist due to the occurrence of unpredictable synergism or antagonism in certain experimental situations. In the present work, we summarize the parallel history of development of CA, IA, and CI models. We also summarize the applicability of these concepts in ecotoxicology and how their information may be integrated, as well as the possibility of prediction of synergism. Inside the box, the main question remaining is whether it is worthy to consider departures from additivity in mixture risk assessment and how to predict interactions among certain mixture components. Outside the box, the main question is whether the results observed under the experimental constraints imposed by fractional approaches are a de fide reflection of what it would be expected from chemical mixtures in real world circumstances.

  2. Chemical use

    Data.gov (United States)

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

  3. Chemical Reactors.

    Science.gov (United States)

    Kenney, C. N.

    1980-01-01

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

  4. Cytotoxicity of calcium enriched mixture cement compared with mineral trioxide aggregate and intermediate restorative material.

    Science.gov (United States)

    Mozayeni, Mohammad A; Milani, Amin S; Marvasti, Laleh A; Asgary, Saeed

    2012-08-01

    Calcium enriched mixture (CEM) cement has been recently invented by the last author. It is composed of calcium oxide, calcium phosphate, calcium silicate and calcium sulphate; however, it has a different chemical composition to mineral trioxide aggregate (MTA). The purpose of this ex vivo study was to investigate the cytotoxicity of CEM cement, and compare it with intermediate restorative material (IRM) and MTA. The materials were tested in fresh and set states on L929 fibroblasts to assess their cytotoxicity. The cell viability responses were evaluated with methyl-tetrazolium bromide assay and Elisa reader at 1, 24 and 168 h (7 days). The tested materials were eluted with L929 culture medium according to international standard organisation 109935 standard. Distilled water and culture medium served as positive and negative controls, respectively. Differences in cytotoxicity were evaluated by one-way anova and t-tests. The cytotoxicity of the materials was statistically different at the three time intervals (P IRM subgroups were the most cytotoxic root-end/dental material (P IRM because of lower cytotoxicity. CEM cement also has good biocompatibility as well as lower estimated cost to MTA and seems to be a promising dental material.

  5. Visualization of self-ignition regimes in hydrogen-air mixtures under shock waves focusing

    Science.gov (United States)

    Gelfand, Boris E.; Khomik, Sergei V.; Medvedev, Sergei P.; Groenig, Hans; Olivier, Herbert

    2001-04-01

    The investigation of self-ignition dynamics followed by combustion has an essential significance for the organization of working cycle in internal combustion engines. The parameters of the process are influenced by the geometry of reactive volume, specific features of the generation of heat release centers, as well as gas-dynamics consequences of the propagation of chemical reaction fronts (formation of the pressure and/or shock waves in reactive volume). Registration of explosive processes using pressure transducers does not provide sufficient information on the localization and dynamics of self-ignition centers. Also unacceptable are the standard radiation detectors due to distortions connected with scattering. Two variants of visualization of the phenomena accompanying self-ignition hydrogen-containing combustible mixtures now are used: (1) Cranz - Schardin spark chamber and (2) powerful laser light source and projection of the image to a film located inside the rotating mirror chamber. In the present work the results of the application of two above- mentioned variants of visualization for the self-ignition investigation are presented.

  6. Internally mixed soot, sulfates, and organic matter in aerosol particles from Mexico City

    Directory of Open Access Journals (Sweden)

    K. Adachi

    2008-05-01

    Full Text Available Soot particles are major aerosol constituents that result from emissions of burning of fossil fuel and biomass. Because they both absorb sunlight and contribute to cloud formation, they are an influence on climate on local, regional, and global scales. It is therefore important to evaluate their optical and hygroscopic properties and those effects on the radiation budget. Those properties commonly change through reaction with other particles or gases, resulting in complex internal mixtures. Using transmission electron microscopy, we measured ~8000 particles (25 samples with aerodynamic diameters from 0.05 to 0.3 μm that were collected in March 2006 from aircraft over Mexico City (MC and adjacent areas. More than 50% of the particles consist of internally mixed soot, organic matter, and sulfate. Imaging combined with chemical analysis of individual particles show that many are coated, consist of aggregates, or both. Coatings on soot particles can amplify their light absorption, and coagulation with sulfates changes their hygroscopic properties, resulting in shorter lifetime. Our results suggest that a mixture of materials from multiple sources such as vehicles, power plants, and biomass burning occurs in individual particles, thereby increasing their complexity. Through changes in their optical and hygroscopic properties, internally mixed soot particles have a greater effect on the regional climate than uncoated soot particles. Moreover, soot occurs in more than 60% of all particles in the MC plumes, suggesting its important role in the formation of secondary aerosol particles.

  7. Quantitative genetic activity graphical profiles for use in chemical evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Waters, M.D. [Environmental Protection Agency, Washington, DC (United States); Stack, H.F.; Garrett, N.E.; Jackson, M.A. [Environmental Health Research and Testing, Inc., Research Triangle Park, NC (United States)

    1990-12-31

    A graphic approach, terms a Genetic Activity Profile (GAP), was developed to display a matrix of data on the genetic and related effects of selected chemical agents. The profiles provide a visual overview of the quantitative (doses) and qualitative (test results) data for each chemical. Either the lowest effective dose or highest ineffective dose is recorded for each agent and bioassay. Up to 200 different test systems are represented across the GAP. Bioassay systems are organized according to the phylogeny of the test organisms and the end points of genetic activity. The methodology for producing and evaluating genetic activity profile was developed in collaboration with the International Agency for Research on Cancer (IARC). Data on individual chemicals were compiles by IARC and by the US Environmental Protection Agency (EPA). Data are available on 343 compounds selected from volumes 1-53 of the IARC Monographs and on 115 compounds identified as Superfund Priority Substances. Software to display the GAPs on an IBM-compatible personal computer is available from the authors. Structurally similar compounds frequently display qualitatively and quantitatively similar profiles of genetic activity. Through examination of the patterns of GAPs of pairs and groups of chemicals, it is possible to make more informed decisions regarding the selection of test batteries to be used in evaluation of chemical analogs. GAPs provided useful data for development of weight-of-evidence hazard ranking schemes. Also, some knowledge of the potential genetic activity of complex environmental mixtures may be gained from an assessment of the genetic activity profiles of component chemicals. The fundamental techniques and computer programs devised for the GAP database may be used to develop similar databases in other disciplines. 36 refs., 2 figs.

  8. Fibril assembly in whey protein mixtures

    NARCIS (Netherlands)

    Bolder, S.G.

    2007-01-01

    The objective of this thesis was to study fibril assembly in mixtures of whey proteins. The effect of the composition of the protein mixture on the structures and the resulting phase behaviour was investigated. The current work has shown that beta-lactoglobulin is responsible for the fibril assembly

  9. Robust classification using mixtures of dependency networks

    DEFF Research Database (Denmark)

    Gámez, José A.; Mateo, Juan L.; Nielsen, Thomas Dyhre

    2008-01-01

    -ups are often obtained at the expense of accuracy. In this paper we try to address this issue through the use of mixtures of dependency networks. To reduce learning time and improve robustness when dealing with data sparse classes, we outline methods for reusing calculations across mixture components. Finally...

  10. Two-microphone Separation of Speech Mixtures

    DEFF Research Database (Denmark)

    2006-01-01

    Matlab source code for underdetermined separation of instaneous speech mixtures. The algorithm is described in [1] Michael Syskind Pedersen, DeLiang Wang, Jan Larsen and Ulrik Kjems: ''Two-microphone Separation of Speech Mixtures,'' 2006, submitted for journal publoication. See also, [2] Michael...

  11. Supercritical separation process for complex organic mixtures

    Science.gov (United States)

    Chum, Helena L.; Filardo, Giuseppe

    1990-01-01

    A process is disclosed for separating low molecular weight components from complex aqueous organic mixtures. The process includes preparing a separation solution of supercritical carbon dioxide with an effective amount of an entrainer to modify the solvation power of the supercritical carbon dioxide and extract preselected low molecular weight components. The separation solution is maintained at a temperature of at least about 70.degree. C. and a pressure of at least about 1,500 psi. The separation solution is then contacted with the organic mixtures while maintaining the temperature and pressure as above until the mixtures and solution reach equilibrium to extract the preselected low molecular weight components from the organic mixtures. Finally, the entrainer/extracted components portion of the equilibrium mixture is isolated from the separation solution.

  12. Separating a water-propanol mixture using PDMS pervaporation membranes

    Directory of Open Access Journals (Sweden)

    Mahacine Amrani

    2010-04-01

    Full Text Available Recovering and purifying organic solvents during chemical and pharmaceutical synthesis has great economic and environmental importance. Water-alcohol mixture pervaporation was investigated using a pervaporation cell and hy-drophobic membranes. This work studied polydimethylsiloxane (PDMS membrane performance and hydrophobic membranes for removing propanol from aqueous mixtures. PDMS is recognised as being alcohol permselective du-ring pervaporation. It was also observed that water was transferred through a hydrophobic membrane as water’s molecular size is smaller than that of propanol. A laboratory-scale pervaporation unit was used for studying this membrane’s separation characteristics in terms of pervaporation flux and selectivity for feeds containing up to water mass and 30°C-50°C. Total propanol/water flux was observed to vary as operating temperature increased. Although PDMS membranes presented good characteristics for separating water/propanol mixtures, the separation factor and pervaporation flow decreased as water content in the feed increased. The tested membrane was found to be very e-fficient for water concentrations of less than 0.3, corresponding to total flux transfer maximum.

  13. Treating leachate mixture with anaerobic ammonium oxidation technology

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hong-guo; ZHOU Shao-qi

    2006-01-01

    Large amounts of ammonium and a low content of biodegradable chemical oxygen demand(COD) are contained in leachate from aged landfills, together with the effluent containing high concentration of nitric nitrogen after biochemical treatment.Treatment effect of anaerobic ammonium oxidation (anammox) process on the mixture of the leachate and its biochemical effluent was investigated. The results show that the average removal efficiencies of ammonium, nitric nitrogen and total nitrogen are 87.51%,74.95% and 79.59%, respectively, corresponding to the average ratio of removed nitric nitrogen to ammonium, i.e. 1.14 during the steady phase of anammox activity. The mean removal efficiency of COD is only 24.01% during the experimental period. The demand of total phosphorous for the anammox process is unobvious. Especially, the alkalinity and pH value of the effluent are close to those of the influent during the steady phase of anammox activity. In addition, it is demonstrated that the status of the anammox bioreactor can be indicated by the alkalinity and pH value during the course of the experiment. The anammox bioreactor has shown potential for nitrogen removal in the leachate mixture. However, COD and total phosphorous in the leachate mixture need further treatment for removal efficiencies of COD and total phosphorous are not good in the anammox bioreactor.

  14. Simulation study of water and sugar dynamics in supercooled mixtures

    Science.gov (United States)

    Molinero, Valeria; Cagin, Tahir; Goddard, William A.

    2003-03-01

    Water dynamics in concentrated carbohydrate solutions is of utmost importance in food and pharmaceutical technology, where low water mobility is desirable to slow down chemical degradation and preserve biomolecules. We have studied the microscopic mechanism of water diffusion in binary and polydisperse malto-oligosaccharides and water mixtures by means of molecular dynamics simulations. The computations were performed with a coarse grain model (M3B), derived from atomistic simulations of water and malto-oligosaccharides. The use of the M3B model permits simulations of the order of 0.1 microsecond, thus allowing us to explore water dynamics from the liquid to the deep supercooled regime. The dynamics of water confined in the sugar matrix is slowed down with respect to bulk water. We found that at low moisture content and low temperature, ranslational diffusion of water and glucose rotation proceed through a hopping-diffusion mechanism. Moreover, we found water mobility to be heterogeneous: there is a broad distribution of time scales for different water molecules in the mixtures. We discuss whether there is a relationship between the heterogeneous structure of these mixtures in the sub-nanometer scale and the heterogeneous dynamics of water molecules.

  15. HUMIFIED FRACTION OF ORGANIC MATTER DUE TO PLANT MIXTURE CULTIVATION

    Directory of Open Access Journals (Sweden)

    TONY JARBAS FERREIRA CUNHA

    2016-01-01

    Full Text Available The aim of this study was to assess the organic matter changes in quantity and quality, particularly of the humic fraction in the surface layer (0–20 cm, of a Typic Plinthustalf soil under different management of plant mixtures used as green manure for mango (Mangifera indica L. crops. The plant mixtures, which were seeded between rows of mango trees, were formed by two groups of leguminous and non-leguminous plants. Prior to sowing, seeds were combined in different proportions and compositions constituting the following treatments: 100% non-leguminous species (NL; 100% leguminous species (L; 75% L and 25% NL; 50% L and 50% NL; 25% L and 75% NL; and 100% spontaneous vegetation, considered a control. The plant mixtures that grew between rows of mango trees caused changes in the chemical composition of the soil organic matter, especially for the treatments 50% L and 50% NL and 25% L and 75% NL, which increased the content of humic substances in the soil organic matter. However, the treatment 25% L and 75% NL was best at minimising loss of total organic carbon from the soil. The humic acids studied have mostly aliphatic characteristics, showing large amounts of carboxylic and nitrogen groups and indicating that most of the organic carbon was formed by humic substances, with fulvic acid dominating among the alkali soluble fractions.

  16. Phenol and cresol mixture degradation by the yeast Trichosporon cutaneum.

    Science.gov (United States)

    Alexieva, Z; Gerginova, M; Manasiev, J; Zlateva, P; Shivarova, N; Krastanov, A

    2008-11-01

    Most industrial wastes contain different organic mixtures, making important the investigation on the microbial destruction of composite substrates. The capability of microbes to remove harmful chemicals from polluted environments strongly depends on the presence of other carbon and energy substrates. The effect of mixtures of phenol- and methyl-substituted phenols (o-, m-, p-cresol) on the growth behaviour and degradation capacity of Trichosporon cutaneum strain was investigated. The cell-free supernatants were analysed by HPLC. It was established that the presence of o-, m- and p- cresol has not prevented complete phenol assimilation but had significant delaying effect on the phenol degradation dynamics. The mutual influence of phenol and p-cresol was investigated. We developed the kinetic model on the basis of Haldane kinetics, which used model parameters from single-substrate experiments to predict the outcome of the two-substrate mixture experiment. The interaction coefficients indicating the degree to which phenol affects the biodegradation of p-cresol and vice versa were estimated. Quantitative estimation of interaction parameters is essential to facilitate the application of single or mixed cultures to the bio-treatment of hazardous compounds.

  17. A methodology to relate octane numbers of binary and ternary n-heptane, iso-octane and toluene mixtures with simulated ignition delay times

    KAUST Repository

    Badra, Jihad A.

    2015-08-11

    Predicting octane numbers (ON) of gasoline surrogate mixtures is of significant importance to the optimization and development of internal combustion (IC) engines. Most ON predictive tools utilize blending rules wherein measured octane numbers are fitted using linear or non-linear mixture fractions on a volumetric or molar basis. In this work, the octane numbers of various binary and ternary n-heptane/iso-octane/toluene blends, referred to as toluene primary reference fuel (TPRF) mixtures, are correlated with a fundamental chemical kinetic parameter, specifically, homogeneous gas-phase fuel/air ignition delay time. Ignition delay times for stoichiometric fuel/air mixtures are calculated at various constant volume conditions (835 K and 20 atm, 825 K and 25 atm, 850 K and 50 atm (research octane number RON-like) and 980 K and 45 atm (motor octane number MON-like)), and for variable volume profiles calculated from cooperative fuel research (CFR) engine pressure and temperature simulations. Compression ratio (or ON) dependent variable volume profile ignition delay times are investigated as well. The constant volume RON-like ignition delay times correlation with RON was the best amongst the other studied conditions. The variable volume ignition delay times condition correlates better with MON than the ignition delay times at the other tested conditions. The best correlation is achieved when using compression ratio dependent variable volume profiles to calculate the ignition delay times. Most of the predicted research octane numbers (RON) have uncertainties that are lower than the repeatability and reproducibility limits of the measurements. Motor octane number (MON) correlation generally has larger uncertainties than that of RON.

  18. Which chemicals drive biological effects in wastewater and recycled water?

    Science.gov (United States)

    Tang, Janet Y M; Busetti, Francesco; Charrois, Jeffrey W A; Escher, Beate I

    2014-09-01

    Removal of organic micropollutants from wastewater during secondary treatment followed by reverse osmosis and UV disinfection was evaluated by a combination of four in-vitro cell-based bioassays and chemical analysis of 299 organic compounds. Concentrations detected in recycled water were below the Australian Guidelines for Water Recycling. Thus the detected chemicals were considered not to pose any health risk. The detected pesticides in the wastewater treatment plant effluent and partially advanced treated water explained all observed effects on photosynthesis inhibition. In contrast, mixture toxicity experiments with designed mixtures containing all detected chemicals at their measured concentrations demonstrated that the known chemicals explained less than 3% of the observed cytotoxicity and less than 1% of the oxidative stress response. Pesticides followed by pharmaceuticals and personal care products dominated the observed mixture effects. The detected chemicals were not related to the observed genotoxicity. The large proportion of unknown toxicity calls for effect monitoring complementary to chemical monitoring.

  19. International indsats

    DEFF Research Database (Denmark)

    Sachs, Therese

    En analyse af Beredskabsstyrelsens internationale engagement og muligheder for international indsats fremover. Forslag til struktur logistisk og materielt samt til udvikling af personel-kompetencer......En analyse af Beredskabsstyrelsens internationale engagement og muligheder for international indsats fremover. Forslag til struktur logistisk og materielt samt til udvikling af personel-kompetencer...

  20. Kinetic Modeling of Gasoline Surrogate Components and Mixtures under Engine Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Mehl, M; Pitz, W J; Westbrook, C K; Curran, H J

    2010-01-11

    Real fuels are complex mixtures of thousands of hydrocarbon compounds including linear and branched paraffins, naphthenes, olefins and aromatics. It is generally agreed that their behavior can be effectively reproduced by simpler fuel surrogates containing a limited number of components. In this work, an improved version of the kinetic model by the authors is used to analyze the combustion behavior of several components relevant to gasoline surrogate formulation. Particular attention is devoted to linear and branched saturated hydrocarbons (PRF mixtures), olefins (1-hexene) and aromatics (toluene). Model predictions for pure components, binary mixtures and multicomponent gasoline surrogates are compared with recent experimental information collected in rapid compression machine, shock tube and jet stirred reactors covering a wide range of conditions pertinent to internal combustion engines (3-50 atm, 650-1200K, stoichiometric fuel/air mixtures). Simulation results are discussed focusing attention on the mixing effects of the fuel components.

  1. Combining Passive Sampling with Toxicological Characterization of Complex Mixtures of Pollutants from the Aquatic Environment.

    Science.gov (United States)

    Jahnke, Annika; Witt, Gesine; Schäfer, Sabine; Haase, Nora; Escher, Beate I

    2016-08-04

    The combination of polymer-based passive sampling to collect complex environmental mixtures of pollutants, the transfer of these mixtures into bioassays, and their related toxicological characterization is still in its infancy. However, this approach has considerable potential to improve environmental hazard and risk assessment for two reasons. First, the passive sampler collects a broad range of chemicals representing the fraction of compounds available for diffusion and (bio)uptake, excluding a large part of the matrix; thus, extensive sample cleanup which could discriminate certain compounds can be avoided. Second, the toxicological characterization of samples using bioassays is complementary to chemical (target) analysis within environmental monitoring because it captures all chemicals exerting the same mode of toxic action and acting jointly in mixtures, thus providing a comprehensive picture of their overall combined effects. The scientific literature describes a range of examples from the water phase where passive sampling is usually carried out in the kinetic uptake regime for most chemicals although some may already have reached equilibrium. The composition of the chemical mixture changes from the water phase to the passive sampling material because of kinetic effects and polymer/water partition coefficients which depend on the chemicals' hydrophobicity. In contrast, only a few applications in sediment and biota have been described, but amongst these some pioneering studies have demonstrated the feasibility and potential of this combined approach. This chapter gives an overview of what has been carried out in this research area, focusing on opportunities and challenges, and points out desirable future developments with a focus on the importance of choosing a suitable combination of sampling and dosing to transfer (or re-establish) the environmental mixture into the bioassay.

  2. Genotoxicity of mixtures of glyphosate and atrazine and their environmental transformation products before and after photoactivation.

    Science.gov (United States)

    Roustan, A; Aye, M; De Meo, M; Di Giorgio, C

    2014-08-01

    The photo-inducible cytogenetic toxicity of glyphosate, atrazine, aminomethyl phosphoric acid (AMPA), desethyl-atrazine (DEA), and their various mixtures was assessed by the in vitro micronucleus assay on CHO-K1 cells. Results demonstrated that the cytogenetic potentials of pesticides greatly depended on their physico-chemical environment. The mixture made with the four pesticides exhibited the most potent cytogenetic toxicity, which was 20-fold higher than those of the most active compound AMPA, and 100-fold increased after light-irradiation. Intracellular ROS assessment suggested the involvement of oxidative stress in the genotoxic impact of pesticides and pesticide mixtures. This study established that enhanced cytogenetic activities could be observed in pesticide mixtures containing glyphosate, atrazine, and their degradation products AMPA and DEA. It highlighted the importance of cocktail effects in environmental matrices, and pointed out the limits of usual testing strategies based on individual molecules, to efficiently estimate environmental risks.

  3. Microencapsulation of coco fatty acid mixture for thermal energy storage with phase change material

    Energy Technology Data Exchange (ETDEWEB)

    Ozonur, Y.; Mazman, M.; Paksoy, H.O.; Evilya, H. [Cukurova University, Adana (Turkey). Dept. of Chemistry

    2005-07-01

    Thermal energy storage systems provide several alternatives for efficient energy use and energy conservation. Microcapsules of natural coco fatty acid mixture were prepared to be used as phase change materials for thermal energy storage. The coacervation technique was used for the microencapsulation process. Several alternatives for the capsule wall material were tried. The microcapsules were characterized according to their geometric profiles, phase transition temperatures, mean particle sizes, chemical stabilities, and their thermal cycling. The diameters of microcapsules prepared in this study were about 1 mm. Coco fatty acid mixtures have kept their geometrical profiles even after 50 thermal cycles for melting and freezing operations in temperature range from 22 to 34{sup o}C. It was found that gelatin+gum Arabic mixture was the best wall material for microencapsulating coco fatty acid mixtures. (author)

  4. Synergistic Disruption of External Male Sex Organ Development by a Mixture of Four Antiandrogens

    DEFF Research Database (Denmark)

    Christiansen, Sofie; Scholze, Martin; Dalgaard, Majken;

    2009-01-01

    are not well described, especially when they exert their actions by differing molecular mechanisms. Objectives: To fill this gap, we investigated the effects of mixtures of a widely used plasticizer, di(2-ethylhexyl) phthalate (DEHP), two fungicides present in food, vinclozolin and prochloraz......By disrupting the action of androgens during gestation, certain chemicals present in food, consumer products and the environment can induce irreversible demasculinisation and malformations of sex organs among male offspring. However, the consequences of simultaneous exposure to such chemicals...

  5. On superfluidity of asymmetric mixture of fermions: How two wrongs make a right

    Science.gov (United States)

    Grigorenko, Ilya; Kezerashvili, Roman Ya.

    2016-10-01

    The existence and stability of the superfluid state in a mixture of two fermion species with different masses and chemical potentials is investigated with respect to the asymmetry between the species. It is found that the mass asymmetry between the two types of particles can be effectively compensated by the asymmetry in their chemical potentials, this way increasing the range of the parameters, which allow the superfluid state.

  6. Steady detonation waves via the Boltzmann equation for a reacting mixture

    CERN Document Server

    Conforto, F; Schürrer, F; Ziegler, I

    2003-01-01

    Based on the Boltzmann equation, the detonation problem is dealt with on a mesoscopic level. The model is based on the assumption that ahead of a shock an explosive gas mixture is in meta stable equilibrium. Starting from the Von Neumann point the chemical reaction, initiated by the pressure jump, proceeds until the chemical equilibrium is reached. Numerical solutions of the derived macroscopic equations as well as the corresponding Hugoniot diagrams which reveal the physical relevance of the mathematical model are provided.

  7. Characterizations of Some N-Substituted-salicylhydrazide in Mixtures by NMR Diffusion Ordered Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    张芳; 于贤勇; 陈忠; 林深; 刘世雄

    2003-01-01

    Several novel N-substituted-salicylhydrazide ligands, most of which are difficult to be purified or recrystallized so that their chemical configurations can not be confirmed by conventional NMR and/or X-ray diffraction techniques, were synthesized in this experiment, and their chemical configurations in mixture were analyzed and characterized by 2D NMR diffusion ordered spectroscopy (DOSY), a labor-saving virtual separation based on diffusion properties,together with several routine NMR techniques.

  8. International Specialization

    DEFF Research Database (Denmark)

    Kleindienst, Ingo; Geisler Asmussen, Christian; Hutzschenreuter, Thomas;

    2012-01-01

    Whether and how international diversification and cross-border arbitrage affects firm performance remains one of the major unresolved research questions in the strategy and international business literatures. We propose that knowing how much a firm has internationally diversified tells us very...... little about performance implications, if we do not know, and do not ask, how the firm has diversified. Therefore, building on the two broad arguments of operating flexibility and location-specific commitment, we develop a theoretical framework that focuses on the extent to which a firm's international...... arbitrage strategy is characterized by specialization versus replication and argue that these different strategies may have differential impact on profitability and risk reduction. Developing a sophisticated measure of international specialization and using a unique panel data set of 92 German MNEs to test...

  9. Toxicity of natural mixtures of organic pollutants in temperate and polar marine phytoplankton

    KAUST Repository

    Echeveste, Pedro

    2016-07-26

    Semivolatile and persistent organic pollutants (POPs) undergo atmospheric transport before being deposited to the oceans, where they partition to phytoplankton organic matter. The goal of this study was to determine the toxicity of naturally occurring complex mixtures of organic pollutants to temperate and polar phytoplankton communities from the Mediterranean Sea, the North East (NE) Atlantic, and Southern Oceans. The cell abundance of the different phytoplankton groups, chlorophyll a concentrations, viability of the cells, and growth and decay constants were monitored in response to addition of a range of concentrations of mixtures of organic pollutants obtained from seawater extracts. Almost all of the phytoplankton groups were significantly affected by the complex mixtures of non-polar and polar organic pollutants, with toxicity being greater for these mixtures than for single POPs or simple POP mixtures. Cocktails\\' toxicity arose at concentrations as low as tenfold the field oceanic levels, probably due to a higher chemical activity of the mixture than of simple POPs mixtures. Overall, smaller cells were the most affected, although Mediterranean picophytoplankton was significantly more tolerant to non-polar POPs than picophytoplankton from the Atlantic Ocean or the Bellingshausen Sea microphytoplankton. © 2016 Elsevier B.V.

  10. Symposium on Short-Term Genetic Bioassays in the Evaluation of Complex Environmental Mixtures

    CERN Document Server

    Sandhu, Shahbeg; Lewtas, Joellen; Claxton, Larry; Strauss, Gary; Nesnow, Stephen

    1985-01-01

    With this proceedings of the fourth symposium on complex mixtures, we continue to revise and extend our knowledge of genetic methods for the evaluation of chemical mixtures in the environment. The early chapters of this volume are devoted to new bioassay techniques that are directly applicable to the monitoring of environments contaminated with genotoxic chemicals. Microbiological methods have been further refined to meet the special needs of atmospheric monitoring so that very small samples may now be efficiently tested. New in situ methods utilizing green plants actually avoid many of the usual difficulties of sample collection and preparation and offer special advantages in monitoring wastewater, sludges, and hazardous wastes. Insects also are being employed very effectively in the evaluation of gaseous air pollutants in controlled laboratory investigations. Increased emphasis has been placed on a comprehensive assessment of the potential of complex mixtures t9 cause various kinds of genetic damage. New as...

  11. Opacity of Hot and Dense Plasmas of a Mixture using an Average-Atom Approach

    Institute of Scientific and Technical Information of China (English)

    袁建民

    2002-01-01

    An average-atom model is proposed to calculate the opacities of hot and dense plasmas of a mixture. A self-consistent scheme is used to reach the requirements of the same temperature and chemical potential for all kinds ofatoms in the mixtures, the same electron density at the boundaries between the atoms, and the electrical neutralitywithin each atomic sphere. The orbital energies and wavefunctions for the bound electrons are calculated withthe Dirac-Slater equations. The occupation numbers at each orbital of each kind of atom are determined by theFermi-Dirac distribution with the same chemical potential for all kinds of atoms. As an example, the opacity ofthe mixture of Au and Cd is calculated at a few temperatures and densities.

  12. The effect of charge motion on mixture preparation and ignition for spark ignition engines with homogeneous combustion processes. A report of the Institute forInternal Combustion Engines and Automotive Engineering, TU Vienna; Einfluss der Ladungsbewegung auf Gemischbildung und Entzuendung bei Otto-Motoren mit homogenen Brennverfahren. Bericht des Instituts fuer Verbrennungskraftmaschinen und Kraftfahrzeugbau der Technischen Universitaet Wien (IVK)

    Energy Technology Data Exchange (ETDEWEB)

    Geringer, B. (ed.); Lauer, T.

    2007-07-01

    The wish to go easy on global oil-resources and the compatibility of environment and traffic are subject of public interest. Therefore, measures must be taken for gasoline engines regarding fuel consumption and CO{sub 2}-emissions. The dethrottling of the intake system by means of residual gas recirculation is a well known measure to reduce the fuel consumption. However, high residual gas concentrations cause a delayed combustion and increased cyclic variations. The specific initiation of charge motion and turbulence in the combustion chamber accelerates and stabilizes the combustion and thus compensates the effects caused by high residual gas concentrations. Because of these complex interactions it is desirable to have the possibility to evaluate the residual gas tolerance of the combustion process at low-load engine operation already during the concept phase. Therefore, it was the aim of this study to develop a method based on numerical simulation that allows a prediction of the combustion stability margin for SI engines with homogeneous combustion for arbitrary in-cylinder flow. Investigations that were carried out with the CFD-method confirmed the acceleration of the combustion with increased turbulence. Further the supporting effect of charge motion on mixture preparation could be pointed out. However, combustion processes with highest swirl-numbers caused a vertical mixture stratification in the combustion chamber with lean mixture at the spark plug resulting in a lower residual gas tolerance. A threshold for a stable combustion could be determined by analyzing the properties of the cylinder charge by means of the flame theory method what further enabled the prediction of the residual gas tolerance of the combustion process and the potential to reduce the fuel consumption. A good correlation between the predicted values of the external residual gas recirculation rate and measurements at the engine test bench could be found. Although improvements of the

  13. Análise por cromatografia gasosa de BTEX nas emissões de motor de combustão interna alimentado com diesel e mistura diesel-biodiesel (B10 Analysis of BTEX in the emissions from an internal combustion engine burning diesel oil and diesel-biodiesel mixture (B10 by gas chromatography

    Directory of Open Access Journals (Sweden)

    Sérgio L. Ferreira

    2008-01-01

    Full Text Available This paper describes the procedures for analysing pollutant gases emitted by engines, such as volatile organic compounds (benzene, toluene, ethylbenzene, o-xylene, m-xylene and p-xylene by using high resolution gas chromatography (HRGC. For IC engine burning, in a broad sense, the use of the B10 mixture reduces drastically the emissions of aromatic compounds. Especially for benzene the reduction of concentrations occurs at the level of about 24.5%. Although a concentration value below 1 µg mL-1 has been obtained, this reduction is extremely significant since benzene is a carcinogenic compound.

  14. Complex prebiotic chemistry within a simple impacting icy mixture

    Science.gov (United States)

    Goldman, Nir

    2013-06-01

    We present results of prebiotic molecule synthesis in shock compressed mixtures of simple ices from quantum molecular dynamics (MD) simulations. Given the likelihood of a CO2-rich primitive atmosphere, it is possible that impact processes of comets or other icy bodies were partially responsible for the creation of prebiotic chemical compounds on early Earth. We have conducted simulations of the chemical reactivity within an oxidized astrophysical icy mixture to close to equilibrium using a density functional tight binding (DFTB) approach. We observe that moderate shock pressures and temperatures (35 GPa and 2800 K) produce a number of functionalized polycyclic aromatic hydrocarbons (PAHs), which remain intact upon expansion and cooling to lower conditions. At higher shock pressures and temperatures (48-62 GPa, 3700-4700 K), we observe the synthesis of a variety of short-lived, exotic C--C and C--N bonded oligomers which decompose upon expansion and cooling to form precursors to amino acids and other prebiotic compounds, such as long chain alkanes, HCN, CH4 and formaldehyde. Our results provide a mechanism for shock synthesis of prebiotic molecules at realistic impact conditions that is independent of external features such as the presence of a catalyst, illuminating UV radiation, or pre-existing conditions on a planet. This work was performed at LLNL under Contract DE-AC52-07NA27344, and was funded by the NASA Astrobiology program.

  15. Using the Mixture Rasch Model to Explore Knowledge Resources Students Invoke in Mathematic and Science Assessments

    Science.gov (United States)

    Zhang, Danhui; Orrill, Chandra; Campbell, Todd

    2015-01-01

    The purpose of this study was to investigate whether mixture Rasch models followed by qualitative item-by-item analysis of selected Programme for International Student Assessment (PISA) mathematics and science items offered insight into knowledge students invoke in mathematics and science separately and combined. The researchers administered an…

  16. Solvatochromic and Kinetic Response Models in (Ethyl Acetate + Chloroform or Methanol Solvent Mixtures

    Directory of Open Access Journals (Sweden)

    L. R. Vottero

    2000-03-01

    Full Text Available The present work analyzes the solvent effects upon the solvatochromic response models for a set of chemical probes and the kinetic response models for an aromatic nucleophilic substitution reaction, in binary mixtures in which both pure components are able to form intersolvent complexes by hydrogen bonding.

  17. Premature reproductive aging in female rats after developmental exposure to mixtures of endocrine disrupters

    DEFF Research Database (Denmark)

    Jacobsen, Pernille Rosenskjold; Petersen, Marta Axelstad; Christiansen, Sofie;

    2013-01-01

    of 13 estrogenic and anti-androgenic chemicals, including phthalates, pesticides, UV-filters, bisphenol A, butylparaben and paracetamol, and the mixture ratio was chosen to reflect high-end human intakes. Groups received combined exposures of 0,100, 150, 200 or 450 times high-end human intake levels...

  18. Stability of isooctane mixtures with 3-pentanone or biacetyl as fluorescence tracers in combustion experiments

    Science.gov (United States)

    Zhang, Rui; Bohac, Stanislav V.; Sick, Volker

    2006-01-01

    Evidence is presented in the literature that common fluorescence tracer/fuel mixtures used in engine experiments, 3-pentanone/isooctane and biacetyl/isooctane, may decompose during extended use and storage. Investigations presented here show that preferential evaporation of the tracer and not chemical decomposition is responsible for observed decreases in fluorescence signal strength in these experiments.

  19. ION COMPOSITION ELUCIDATION (ICE): A HIGH RESOLUTION MASS SPECTROMETRIC TECHNIQUE FOR IDENTIFYING COMPOUNDS IN COMPLEX MIXTURES

    Science.gov (United States)

    When tentatively identifying compounds in complex mixtures using mass spectral libraries, multiple matches or no plausible matches due to a high level of chemical noise or interferences can occur. Worse yet, most analytes are not in the libraries. In each case, Ion Composition El...

  20. Joint toxicity of mixtures of groups of organic aquatic pollutants to the guppy (Poecilia reticulata)

    NARCIS (Netherlands)

    Hermens, J.L.M.; Leeuwangh, Peter; Musch, Aalt

    1985-01-01

    In this study acute lethal concentrations (LC50) to the guppy (Poecilia reticulata) were determined for mixtures of 4 groups of aquatic pollutants. The groups were composed of 11 nonreactive, nonionized organic chemicals, 11 chloroanilines, 11 chlorophenols, and 9 reactive organic halides. Earlier s

  1. Toxicity of mixtures of nephrotoxicants with similar or dissimilar mode of action

    NARCIS (Netherlands)

    Jonker, D.; Woutersen, R.A.; Feron, V.J.

    1996-01-01

    The toxicity of mixtures of chemicals with the same target organ was examined in rats using nephrotoxicants with similar or dissimilar modes of action. In a 4-wk feeding study, lysinoalanine, mercuric chloride, hexachloro-1,3-butadiene and d-limonene, each affecting renal proximal tubular cells but

  2. On the mixture model for multiphase flow

    Energy Technology Data Exchange (ETDEWEB)

    Manninen, M.; Taivassalo, V. [VTT Energy, Espoo (Finland). Nuclear Energy; Kallio, S. [Aabo Akademi, Turku (Finland)

    1996-12-31

    Numerical flow simulation utilising a full multiphase model is impractical for a suspension possessing wide distributions in the particle size or density. Various approximations are usually made to simplify the computational task. In the simplest approach, the suspension is represented by a homogeneous single-phase system and the influence of the particles is taken into account in the values of the physical properties. This study concentrates on the derivation and closing of the model equations. The validity of the mixture model is also carefully analysed. Starting from the continuity and momentum equations written for each phase in a multiphase system, the field equations for the mixture are derived. The mixture equations largely resemble those for a single-phase flow but are represented in terms of the mixture density and velocity. The volume fraction for each dispersed phase is solved from a phase continuity equation. Various approaches applied in closing the mixture model equations are reviewed. An algebraic equation is derived for the velocity of a dispersed phase relative to the continuous phase. Simplifications made in calculating the relative velocity restrict the applicability of the mixture model to cases in which the particles reach the terminal velocity in a short time period compared to the characteristic time scale of the flow of the mixture. (75 refs.)

  3. Foaming of mixtures of pure hydrocarbons

    Science.gov (United States)

    Robinson, J. V.; Woods, W. W.

    1950-01-01

    Mixtures of pure liquid hydrocarbons are capable of foaming. Nine hydrocarbons were mixed in pairs, in all possible combinations, and four proportions of each combination. These mixtures were sealed in glass tubes, and the foaming was tested by shaking. Mixtures of aliphatic with other aliphatic hydrocarbons, or of alkyl benzenes with other alkyl benzenes, did not foam. Mixtures of aliphatic hydrocarbons with alkyl benzenes did foam. The proportions of the mixtures greatly affected the foaming, the maximum foaming of 12 of 20 pairs being at the composition 20 percent aliphatic hydrocarbon, 80 percent alkyl benzene. Six seconds was the maximum foam lifetime of any of these mixtures. Aeroshell 120 lubricating oil was fractionated into 52 fractions and a residue by extraction with acetone in a fractionating extractor. The index of refraction, foam lifetime, color, and viscosity of these fractions were measured. Low viscosity and high index fractions were extracted first. The viscosity of the fractions extracted rose and the index decreased as fractionation proceeded. Foam lifetimes and color were lowest in the middle fractions. Significance is attached to the observation that none of the foam lifetimes of the fractions or residue is as high as the foam lifetime of the original Aeroshell, indicating that the foaming is not due to a particular foaming constituent, but rather to the entire mixture.

  4. Sustainable Development in Chemical Fiber Industry

    Institute of Scientific and Technical Information of China (English)

    Flora Zhao

    2012-01-01

    The 18th China International Man-Made Fiber Conference (Xiaoshan 2012), themed on "How does Chemical Fiber Industry to Realize Sustainable Development against the Background of High-cost Era?", kicked off in Hangzhou on September 6th, 2012. More than 600 representatives from nearly 20 major chemical fiber manufacturing countries and regions all over the world were gathered together to discuss the sustainable development strategies of international chemical fiber industry in the context of the current compficated environment from different perspectives.

  5. Flows and chemical reactions in an electromagnetic field

    CERN Document Server

    Prud'homme, Roger

    2014-01-01

    This book - a sequel of previous publications 'Flows and Chemical Reactions', 'Chemical Reactions Flows in Homogeneous Mixtures' and 'Chemical Reactions and Flows in Heterogeneous Mixtures' - is devoted to flows with chemical reactions in the electromagnetic field. The first part, entitled basic equations, consists of four chapters. The first chapter provides an overview of the equations of electromagnetism in Minkowski spacetime. This presentation is extended to balance equations, first in homogeneous media unpolarized in the second chapter and homogeneous fluid medium polarized in the thir

  6. International Reports.

    Science.gov (United States)

    Valauskas, Edward J.; Stowe, Jennifer L.; Haycock, Ken; Dodd, Frances

    1998-01-01

    Presents three reports: International Federation of Library Associations and Institutions; Special Libraries Association; and Canadian library trends, focusing on information technology and access to information and rights and examining provincial libraries and library education. (PEN)

  7. International Health

    Science.gov (United States)

    ... create refugee populations with immediate and long-term health problems. Some of the major diseases currently affecting ... also an international problem which can affect people's health. Many countries and health organizations are working together ...

  8. Juris International

    CERN Document Server

    A database on international trade law aimed at lawyers and legal counsel in developing and transition economies. Juris International is a multilingual collection (English, Spanish, and French) of legal information on international trade. Juris International aims to facilitate and reduce the work involved in research for business lawyers, advisers and in-house counsel, and state organizations in developing nd transition economies, by providing access to texts which have often been difficult to obtain. Its objective is to gather a large quantity of basic information at one site (favoring complete legal texts), without the need to send for the information, and consequently without excessive communication costs for users who d benefit from an efficient and cheap telecommunications network.

  9. EFFECTS OF MIXTURES OF PHTHALATES, PESTICIDES AND TCDD ON SEXUAL DIFFERENTIATON IN RATS: A RISK FRAMEWORK BASED UPON DISRUPTION OF COMMON DEVELOPING SYSTEMS

    Science.gov (United States)

    Since humans are exposed to more than one chemical at a time, concern has arisen about the effects of mixtures of chemicals on human reproduction and development. We are conducting studies to determine the 1) classes of chemicals that disrupt sexual differentiation via different ...

  10. Screening of optimum proportion and field effect of mixtures of Bt engineering strain WG-001 and chemical insecticides against Plutella xylostella%Bt工程菌WG-001与化学杀虫剂复配最佳配方筛选及田间防效研究

    Institute of Scientific and Technical Information of China (English)

    张聪冲; 邱浩; 覃春华; 游红; 李建洪

    2011-01-01

    为了延缓小菜蛾Plutella xylostella(L.)抗药性的产生和发展,筛选Bt工程菌WG-001与化学杀虫剂的最佳复配配方,本研究采用浸叶法分别测定了Bt工程菌WG-001与茚虫威、丁醚脲和巴丹复配对小菜蛾的增效作用.结果表明,当Bt工程菌WG-001与茚虫威以有效成分之比为100.10:0.72复配时,增效作用最强,共毒系数为178.05.而Bt工程菌WG-001分别与丁醚脲和巴丹复配表现相加或拮抗作用.田间试验结果表明,Bt工程菌WG-001与茚虫威以100.10:0.72的有效成分之比进行复配后,药后7 d,500倍液对小菜蛾的平均防效为84.88%,显著优于Bt工程菌WG-001和茚虫威单用的平均防效.%The relative effectiveness of mixtures of the Bt strain WG-001 with the pesticides indoxacarb, diafenthiuron and cartap for controlling the diamondback moth ( DBM ) Plutella xylostella ( L. ) was determined using the leaf-dipping method. The results indicate that a 100.10:0.72 mixture of Bt strain WG-001 and indoxacarb was the most synergetic with a co-toxicity coefficient (CTC) of 178.05. Mixtures of Bt strain WG-001 with diafenthiuron or cartap had an additive or antagonistic action, respectively. Results of a field trial showed that the average control effect of a 500 times dilution of the Bt strain WG-001 and indoxacarb mixture was 84.88% 7 days after treatment, significantly higher than using either Bt WG-001 or indoxacarb separately ( P <0.05 ).

  11. Internal education

    OpenAIRE

    Anita Zagorc

    2016-01-01

    Research Question (RQ): The importance of internal trainings in an organization. Purpose: The purpose of research is to examine and present internal trainings in an organization and their contribution to greater success of an organization. The paper studies employee training in a company, how the organization itself looks after its employees during training, how trainings contribute to further development of organization and the advancement of knowledge for successful operation of organi...

  12. Biodegradation kinetics of select polycyclic aromatic hydrocarbon (PAH) mixtures by Sphingomonas paucimobilis EPA505.

    Science.gov (United States)

    Desai, Anuradha M; Autenrieth, Robin L; Dimitriou-Christidis, Petros; McDonald, Thomas J

    2008-04-01

    Many contaminated sites commonly have complex mixtures of polycyclic aromatic hydrocarbons (PAHs) whose individual microbial biodegradation may be altered in mixtures. Biodegradation kinetics for fluorene, naphthalene, 1,5-dimethylnaphthalene and 1-methylfluorene were evaluated in sole substrate, binary and ternary systems using Sphingomonas paucimobilis EPA505. The first order rate constants for fluorene, naphthalene, 1,5-dimethylnaphthalene, and 1-methylfluorene were comparable; yet Monod parameters were significantly different for the tested PAHs. S. paucimobilis completely degraded all the components in binary and ternary mixtures; however, the initial degradation rates of individual components decreased in the presence of competitive PAHs. Results from the mixture experiments indicate competitive interactions, demonstrated mathematically. The generated model appropriately predicted the biodegradation kinetics in mixtures using parameter estimates from the sole substrate experiments, validating the hypothesis of a common rate-determining step. Biodegradation kinetics in mixtures were affected by the affinity coefficients of the co-occurring PAHs and mixture composition. Experiments with equal concentrations of substrates demonstrated the effect of concentration on competitive inhibition. Ternary experiments with naphthalene, 1,5-dimethylnaphthalene and 1-methylfluorene revealed delayed degradation, where depletion of naphthalene and 1,5-dimethylnapthalene occurred rapidly only after the complete removal of 1-methylfluorene. The substrate interactions observed in mixtures require a multisubstrate model to account for simultaneous degradation of substrates. PAH contaminated sites are far more complex than even ternary mixtures; however these studies clearly demonstrate the effect that interactions can have on individual chemical kinetics. Consequently, predicting natural or enhanced degradation of PAHs cannot be based on single compound kinetics as this

  13. Gravimetric dilution of calibration gas mixtures (CO2, CO, and CH4 in He balance): Toward their uncertainty estimation

    Science.gov (United States)

    Budiman, Harry; Mulyana, Muhammad Rizky; Zuas, Oman

    2017-01-01

    Uncertainty estimation for the gravimetric dilution of four calibration gas mixtures [carbon dioxide (CO2), carbon monoxide (CO), and methane (CH4) in helium (He) Balance] have been carried out according to the International Organization for Standardization (ISO) of "Guide to the Expression of Uncertainty in Measurement". The uncertainty of the composition of gas mixtures was evaluated to measure the quality, reliability, and comparability of the prepared calibration gas mixtures. The analytical process for the uncertainty estimation is comprised of four main stages such as specification of measurand, identification, quantification of the relevant uncertainty sources, and combination of the individual uncertainty sources. In this study, important uncertainty sources including weighing, gas cylinder, component gas, certified calibration gas mixture (CCGM) added, and purity of the He balance were examined to estimate the final uncertainty of composition of diluted calibration gas mixtures. The results shows that the uncertainties of gravimetric dilution of the four calibration gas mixtures (CO2, CO, and CH4 in He Balance) were found in the range of 5.974% - 7.256% that were expressed as %relative of expanded uncertainty at 95% of confidence level (k=2). The major contribution of sources uncertainty to the final uncertainty arose from the uncertainty related to the certified calibration gas mixture (CCGM) which was the uncertainty value stated in the CCGM certificate. The verification of calibration gas mixtures composition shows that the gravimetric values of calibration gas mixtures were consistent with the results of measurement using gas chromatography flame ionization detector equipped by methanizer.

  14. The disentangling number for phylogenetic mixtures

    CERN Document Server

    Sullivant, Seth

    2011-01-01

    We provide a logarithmic upper bound for the disentangling number on unordered lists of leaf labeled trees. This results is useful for analyzing phylogenetic mixture models. The proof depends on interpreting multisets of trees as high dimensional contingency tables.

  15. Nitrocarburizing in ammonia-hydrocarbon gas mixtures

    DEFF Research Database (Denmark)

    Pedersen, Hanne; Christiansen, Thomas; Somers, Marcel A. J.

    2011-01-01

    The present work investigates the possibility of nitrocarburising in ammonia-acetylene-hydrogen and ammonia-propene-hydrogen gas mixtures, where unsaturated hydrocarbon gas is the carbon source during nitrocarburising. Consequently, nitrocarburising is carried out in a reducing atmosphere...

  16. Model structure selection in convolutive mixtures

    DEFF Research Database (Denmark)

    Dyrholm, Mads; Makeig, Scott; Hansen, Lars Kai

    2006-01-01

    The CICAAR algorithm (convolutive independent component analysis with an auto-regressive inverse model) allows separation of white (i.i.d) source signals from convolutive mixtures. We introduce a source color model as a simple extension to the CICAAR which allows for a more parsimoneous represent......The CICAAR algorithm (convolutive independent component analysis with an auto-regressive inverse model) allows separation of white (i.i.d) source signals from convolutive mixtures. We introduce a source color model as a simple extension to the CICAAR which allows for a more parsimoneous...... representation in many practical mixtures. The new filter-CICAAR allows Bayesian model selection and can help answer questions like: 'Are we actually dealing with a convolutive mixture?'. We try to answer this question for EEG data....

  17. Nitrocarburising in ammonia-hydrocarbon gas mixtures

    DEFF Research Database (Denmark)

    Pedersen, Hanne; Christiansen, Thomas; Somers, Marcel A. J.

    2010-01-01

    The present work investigates the possibility of nitrocarburising in ammonia-acetylene-hydrogen and ammoniapropene- hydrogen gas mixtures, where unsaturated hydrocarbon gas is the carbon source during nitrocarburising. Consequently, nitrocarburising is carried out in a reducing atmosphere...

  18. Model structure selection in convolutive mixtures

    DEFF Research Database (Denmark)

    Dyrholm, Mads; Makeig, S.; Hansen, Lars Kai

    2006-01-01

    The CICAAR algorithm (convolutive independent component analysis with an auto-regressive inverse model) allows separation of white (i.i.d) source signals from convolutive mixtures. We introduce a source color model as a simple extension to the CICAAR which allows for a more parsimonious represent......The CICAAR algorithm (convolutive independent component analysis with an auto-regressive inverse model) allows separation of white (i.i.d) source signals from convolutive mixtures. We introduce a source color model as a simple extension to the CICAAR which allows for a more parsimonious...... representation in many practical mixtures. The new filter-CICAAR allows Bayesian model selection and can help answer questions like: ’Are we actually dealing with a convolutive mixture?’. We try to answer this question for EEG data....

  19. Effects of binary mixtures of inducers (toluene analogs) and of metals on bioluminescence induction of a recombinant bioreporter strain.

    Science.gov (United States)

    Kong, In Chul

    2014-10-13

    This paper investigated the effects of binary mixtures of bioluminescence inducers (toluene, xylene isomers, m-toluate) and of metals (Cu, Cd, As(III), As(V), and Cr) on bioluminescence activity of recombinant (Pm-lux) strain KG1206. Different responses and sensitivities were observed depending on the types and concentrations of mixtures of inducers or metals. In the case of inducer mixtures, antagonistic and synergistic modes of action were observed, whereas metal mixtures showed all three modes of action. Antagonistic mode of action was most common for mixtures of indirect inducers, which showed bioluminescence ranging from 29% to 62% of theoretically expected effects (P(E)). On the other hand, synergistic mode of action was observed for mixtures of direct and indirect inducers, which showed bioluminescence between 141% and 243% of P(E). In the case of binary metal mixtures, bioluminescence activities were ranged from 62% to 75% and 113% to 164% of P(E) for antagonistic and synergistic modes of action, respectively (p-values 0.0001-0.038). Therefore, mixture effects could not be generalized since they were dependent on both the types and concentrations of chemicals, suggesting that biomonitoring may constitute a better strategy by investigating types and concentrations of mixture pollutants at contaminated sites.

  20. Fitting mixture distributions to phenylthiocarbamide (PTC) sensitivity.

    OpenAIRE

    Jones, P N; G.J. McLachlan

    1991-01-01

    A technique for fitting mixture distributions to phenylthiocarbamide (PTC) sensitivity is described. Under the assumptions of Hardy-Weinberg equilibrium, a mixture of three normal components is postulated for the observed distribution, with the mixing parameters corresponding to the proportions of the three genotypes associated with two alleles A and a acting at a single locus. The corresponding genotypes AA, Aa, and aa are then considered to have separate means and variances. This paper is c...