Sample records for organic azeotropic mixtures

  1. Separation of organic azeotropic mixtures by pervaporation

    SciTech Connect

    Baker, R.W.

    1991-12-01

    Distillation is a commonly used separation technique in the petroleum refining and chemical processing industries. However, there are a number of potential separations involving azetropic and close-boiling organic mixtures that cannot be separated efficiently by distillation. Pervaporation is a membrane-based process that uses selective permeation through membranes to separate liquid mixtures. Because the separation process is not affected by the relative volatility of the mixture components being separated, pervaporation can be used to separate azetropes and close-boiling mixtures. Our results showed that pervaporation membranes can be used to separate azeotropic mixtures efficiently, a result that is not achievable with simple distillation. The membranes were 5--10 times more permeable to one of the components of the mixture, concentrating it in the permeate stream. For example, the membrane was 10 times more permeable to ethanol than methyl ethyl ketone, producing 60% ethanol permeate from an azeotropic mixture of ethanol and methyl ethyl ketone containing 18% ethanol. For the ethyl acetate/water mixture, the membranes showed a very high selectivity to water (> 300) and the permeate was 50--100 times enriched in water relative to the feed. The membranes had permeate fluxes on the order of 0.1--1 kg/m{sup 2}{center dot}h in the operating range of 55--70{degrees}C. Higher fluxes were obtained by increasing the operating temperature.

  2. Separation of organic azeotropic mixtures by pervaporation. Final technical report

    SciTech Connect

    Baker, R.W.

    1991-12-01

    Distillation is a commonly used separation technique in the petroleum refining and chemical processing industries. However, there are a number of potential separations involving azetropic and close-boiling organic mixtures that cannot be separated efficiently by distillation. Pervaporation is a membrane-based process that uses selective permeation through membranes to separate liquid mixtures. Because the separation process is not affected by the relative volatility of the mixture components being separated, pervaporation can be used to separate azetropes and close-boiling mixtures. Our results showed that pervaporation membranes can be used to separate azeotropic mixtures efficiently, a result that is not achievable with simple distillation. The membranes were 5--10 times more permeable to one of the components of the mixture, concentrating it in the permeate stream. For example, the membrane was 10 times more permeable to ethanol than methyl ethyl ketone, producing 60% ethanol permeate from an azeotropic mixture of ethanol and methyl ethyl ketone containing 18% ethanol. For the ethyl acetate/water mixture, the membranes showed a very high selectivity to water (> 300) and the permeate was 50--100 times enriched in water relative to the feed. The membranes had permeate fluxes on the order of 0.1--1 kg/m{sup 2}{center_dot}h in the operating range of 55--70{degrees}C. Higher fluxes were obtained by increasing the operating temperature.

  3. Near azeotropic mixture substitute

    NASA Technical Reports Server (NTRS)

    Jones, Jack A. (Inventor)

    1996-01-01

    The present invention comprises a refrigerant mixture consisting of a first mole fraction of 1,1,1,2-tetrafluoroethane (R134a) and a second mole fraction of a component selected from the group consisting of a mixture of CHClFCF.sub.3 (R124) and CH.sub.3 CClF.sub.2 (R142b); a mixture of CHF.sub.2 CH.sub.3 (R152a) and CHClFCF.sub.3 (R124); a mixture of CHF.sub.2 CH.sub.3 (R152a) and CH.sub.3 CClF.sub.2 (R142b); and a mixture of CHClFCF.sub.3 (R124), CH.sub.3 CClF.sub.2 (R142b) and CHF.sub.2 CH.sub.3 (R152a).

  4. Separation of n-hexane–ethyl acetate mixtures by azeotropic batch distillation with heterogeneous entrainers

    Microsoft Academic Search

    I. Rodriguez-Donis; J. Acosta-Esquijarosa; V. Gerbaud; E. Pardillo-Fondevila; X. Joulia

    2005-01-01

    In this article, a systematic study of the separation of the n-hexane–ethyl acetate mixture with an entrainer by heterogeneous azeotropic batch distillation is performed. Based upon the thermodynamic behaviour of the ternary mixtures, potential entrainers partially miscible with one or two original azeotropic components are chosen. In all cases, the entrainer adds a heterogeneous binary or ternary azeotrope that is

  5. Near azeotropic mixture substitute for dichlorodifluoromethane

    NASA Technical Reports Server (NTRS)

    Jones, Jack A. (Inventor)

    1998-01-01

    A refrigerant and a process of formulating thereof that consists of a mixture of a first mole fraction of CH.sub.2 FCF.sub.3 and a second mole fraction of a component selected from the group consisting of a mixture of CHClFCF.sub.3 and CH.sub.3 CClF.sub.2 ; a mixture of CHF.sub.2 CH.sub.3 and CH.sub.3 CClF.sub.2 ; and a mixture of CHClFCF.sub.3, CH.sub.3 CClF.sub.2 and CHF.sub.2 CH.sub.3.

  6. Near azeotropic mixture substitute for dichlorodifluoromethane

    NASA Technical Reports Server (NTRS)

    Jones, Jack A. (Inventor)

    1996-01-01

    The present invention comprises a refrigerant mixture having two halocarbon components. The first component is present in a mole fraction of about 0.7 to less than 1.0 while the second component is present in a mole fraction of more than 0.0 to about 0.3. The first component is CH.sub.2 FCF.sub.3. The second component can be CHClFCF.sub.3, CH.sub.3 CClF.sub.2, a mixture of CHClFCF.sub.3 and CH.sub.3 CClF.sub.2, a mixture of CHF.sub.2 CH.sub.3 and CHClFCF.sub.3, a mixture of CHF.sub.2 CH.sub.3 and CH.sub.3 CClF.sub.2, or a mixture of CHClFCF.sub.3, CH.sub.3 CClF.sub.2 and CHF.sub.2 CH.sub.3. The preferred embodiment of this invention comprises about 0.7 to less than 1.0 mole fraction CH.sub.2 FCF.sub.3, and more than 0.0 to about 0.3 mole fraction of a mixture of CHClFCF.sub.3 and CH.sub.3 CClF.sub.2. The most preferred embodiment of this invention comprises about 0.7 to less than 1.0 mole fraction CH.sub.2 FCF.sub.3 and more than 0.0 to about 0.3 mole fraction CH.sub.3 CClF.sub.2. The resulting refrigerant has a vapor pressure close to-that of CF.sub.2 Cl.sub.2, a nearly constant vapor pressure with evaporation, and is substantially less damaging to the Earth's ozone layer than CF.sub.2 Cl.sub.2.

  7. Anthracene + Pyrene Solid Mixtures: Eutectic and Azeotropic Character

    PubMed Central

    Rice, James W.; Fu, Jinxia; Suuberg, Eric M.

    2010-01-01

    To better characterize the thermodynamic behavior of a binary polycyclic aromatic hydrocarbon mixture, thermochemical and vapor pressure experiments were used to examine the phase behavior of the anthracene (1) + pyrene (2) system. A solid-liquid phase diagram was mapped for the mixture. A eutectic point occurs at 404 K at x1 = 0.22. A model based on eutectic formation can be used to predict the enthalpy of fusion associated with the mixture. For mixtures that contain x1 < 0.90, the enthalpy of fusion is near that of pure pyrene. This and X-ray diffraction results indicate that mixtures of anthracene and pyrene have pyrene-like crystal structures and energetics until the composition nears that of pure anthracene. Solid-vapor equilibrium studies show that mixtures of anthracene and pyrene form solid azeotropes at x1 of 0.03 and 0.14. Additionally, mixtures at x1 = 0.99 sublime at the vapor pressure of pure anthracene, suggesting that anthracene behavior is not significantly influenced by x2 = 0.01 in the crystal structure. PMID:21116474

  8. Boiling Heat Transfer and Pressure Drop of Non-Azeotropic Mixtures Inside a Horizontal Grooved Tube

    NASA Astrophysics Data System (ADS)

    Kajikawa, Satoru; Ayukawa, Kyozo; Sogo, Motosuke; Okita, Yuji

    The evaporation of HCFC141b, HFC152a and HFC23, and non-azeotropic refrigerant mixture used at the very low temperature refrigeration system is experimentally studied in a horizontal spirally grooved tube with corrugation. The experiments were conducted at 0.03 to 0.47MPa of boiling pressure, 100 kg/(m2s) of mass flux, 1 to 15 kW/ m2 of heat flux, -26 to 21 °C of refrigerant temperature and 11.4 mm of average inner diameter. It is concluded that boiling heat transfer coefficients of single-refrigerant are higher than these of non-azeotropic refrigerant mixture. And dimensionless correlation of the heat transfer coefficirnts, i.e. Lockhart-Martinelli parameters agreed with equation (10) within the limit of ±40 percent. Pressure drops of these refrigerant mixture depend on its liquid density and flow pattern.

  9. Pressure swing distillation for separation of homogeneous azeotropic mixtures in a mass- and heat- integrated column system: operation performance

    Microsoft Academic Search

    Jens-Uwe Repke; Andreas Klein; F. Forner; Gunter Wozny

    2004-01-01

    The separation of a homogeneous azeotropic mixture using pressure swing distillation process is deficient investigated, therefore industrial applications are limited. The dynamic behaviour of a heat- and mass-integrated pressure swing distillation column system to separate an acetonitrile\\/water mixture is analysed. Different control structures are developed and compared by using a rigorous dynamic model written in gProms®. A first validation of

  10. Evaluation of non-azeotropic mixtures containing HFOs as potential refrigerants in refrigeration and high-temperature heat pump systems

    Microsoft Academic Search

    ShengJun Zhang; HuaiXin Wang; Tao Guo

    2010-01-01

    With the increasing environmental concern on global warming, hydrofluoro-olefin (HFOs), possessing low GWP, has attracted\\u000a great attention of many researchers recently. In this study, non-azeotropic mixtures composed of HFOs (HFO-1234yf, HFO-1234ze(z),\\u000a HFO-1234ze(e) and HFO-1234zf) are developed to substitute for HFC-134a and CFC-114 in air-conditioning and high-temperature\\u000a heat pump systems, respectively. The cycle performances were evaluated by an improved theoretical cycle

  11. Electroosmotic Membrane Pump for the separation of water from azeotropic mixtures. Technical progress report, Phase 1

    SciTech Connect

    Lundstrom, J.E.

    1986-03-01

    The Electroosmotic Membrane (EOM) Pump is proposed as a process for saving energy during the separation of azeotropes of alcohol and water. The process is electrically driven and removes water from the process stream through ion-selective membranes by electroosmosis. A laboratory-scale Model Cell was constructed to test the EOM pump concept using commercially available ion exchange membranes. Tests were performed with the Model Cell at various (1) alcohol-water compositions, (2) feed molalities of lithium chloride and lithium bromide in water, (3) stack temperatures, and (4) other operating conditions, such as stack configuration and membrane thickness. As part of the integration of the EOM pump and distillation processes, the effect of salt injection into the reflux line of the distillation column was studied. A conclusion of the study is that the overhead composition can be substantially enriched in alcohol to essentially anhydrous alcohol with salt addition.

  12. azeotropic batch distillation with heterogeneous en trainers

    Microsoft Academic Search

    I. Rodriguez-Donis; J. Acosta-Esquijarosa; V. Gerbaud; E. Pardillo-Fondevila

    In this article, a systematic study of the separati on of the n-hexane - ethyl acetate mixture with an entrainer by heterogeneous azeotropic batch distillation is performed. Based upon the thermodynamic behaviour of the ternary mixtures, potential entrainers partially miscible with one or two original azeotropic compon ents are chosen. In all cases, the entrainer adds a heterogeneous binary or

  13. Two-Phase Flow and Energy Transfer of a Non-Azeotropic Mixture, R-407c, in a Micro-Fin Tube

    NASA Astrophysics Data System (ADS)

    Liu, Xin

    1996-11-01

    This study is to determine experimentally the two-phase flow and energy transfer characteristics of a non-azeotropic refrigerant mixture, R-407c (nominal composition: 23% R-32, 25% R-125, and 52% R-134a). R-407c is a fluid with zero ozone depletion potential and one of several alternatives to currently widely used pure refrigerant HCFC-22. As a non-azeotrope, R-407c has distinctly different characteristics from pure fluids. The phase change of a non-azeotrope under constant pressure does not proceed at a constant temperature but rather over a range of temperature. In addition, the momentum, energy transfer, and mass transfer processes are closely linked. The vapor-liquid interfacial mass transfer rate limits the evaporation or condensation rate, and in turns limits the energy transfer rate. The experiments are conducted in a test apparatus with a fluid sampling port to monitor the composition change of the mixture. The test section consists of six horizontal identical passes, constructed as double tube heat exchangers. Each pass is about 2.2 m long and are connected in order by 7.6 cm radius U-bends. The heated or cooled section of each pass is shorter than the pass length and is 1.8 meter long. The inner (mixture) tube of the test section is a nominal 3/8" inch (9.5 mm) copper tube of 0.348 mm wall thickness with 72 axial fins of 0.185 mm height on its inner surface. The apex angle of the fins is 15 deg. and the helix angle is 0. The annulus-side water, serving as heat source (evaporating mode) or heat sink (condensing mode), flows through the annular space between inner and outer tubes. The tests are conducted at 100 deg F dew point temperature and mass flux from 192,000 to 818,000 lb/hr-ft^2 for condensing, and 50 deg F dew point and mass flux from 70,000 to 394,000 lb/hr-ft^2 for evaporating. The experimental results show that, compared to R-22, two-phase flow frictional pressure gradients of R-407c are about 10% less than R-22. Due to the mass transfer resistance, its condensing coefficients are 15% to 30% lower and its evaporating coefficients are about 20% lower, relative to R-22.

  14. Heat Transfer and Pressure Drop for Flow Boiling of Non-Azeotropic Refrigerant Mixtures of HFC-32/HFC-125/HFC-134a and HFC-32/HFC-134a in Horizontal Tubes

    NASA Astrophysics Data System (ADS)

    Mori, Hideo; Yoshida, Suguru; Ohishi, Katsumi

    Experiments were performed on heat transfer and pressure drop for flow boiling of two non-azeotropic refrigerant mixtures of HFC-32/HFC-125/HFC-134a and HFC-32/HFC-134a at respectively certain compositions,which are expected to be alternatives to HCFC-22,in horizontal smooth and internally,spirally grooved tubes. Almost the same local heat transfer coefficients were obtained for both the mixtures in each tube. In the smooth tube,in the region where nucleate boiling contributes substantially to the heat transfer,the heat transfer coefficients for the mixtures were reduced down to about two-thirds of the value for HCFC-22,due to the effect of a mass transfer resistance on the heat transfer,while they were approximately equal to those for HCFC-22 in the forced convection dominated region. With the grooved tube,the heat transfer was enhanced over the smooth tube,but the enhancement was smaller than that for HCFC-22. In both the tubes,frictional pressure drops for the binary mixture were generally a few to 20 percent higher than those for the ternary mixture and the pure refrigerant,corresponding to the difference in the vapor density.

  15. Understanding the azeotropic diethyl carbonate-water mixture by structural and energetic characterization of DEC(H2O)(n) heteroclusters.

    PubMed

    Ripoll, Juan D; Mejía, Sol M; Mills, Matthew J L; Villa, Aída L

    2015-04-01

    Diethyl carbonate (DEC) is an oxygenated fuel additive. During its synthesis through a promising green process, a DEC-water azeotrope is formed, which decreases DEC production efficiency in the gas phase. Molecular information about this system is scarce but could be of benefit in understanding (and potentially improving) the synthetic process. Therefore, we report a detailed computational study of the conformers of DEC, and their microsolvation with up to four water molecules, with the goal of understanding the observed 1:3 DEC:H2O molar ratio. The most stable DEC conformers (with mutual energy differences < 1.5 kcal mol(-1)) contribute to the energetic and structural properties of the complexes. An exhaustive stochastic exploration of each potential energy surface of DEC-(H2O)n, (where n?=?1, 2, 3, 4) heteroclusters discovered 3, 8, 7, and 4 heterodimers, heterotrimers, heterotetramers, and heteropentamers, respectively, at the MP2/6-311++G(d,p) level of theory. DEC conformers and energies of the most stable structures at each heterocluster size were refined using CCSD(T)/6-311++G(d,p). Energy decomposition, electron density topology, and cooperative effects analyses were carried out to determine the relationship between the geometrical features of the heteroclusters and the non-covalent interaction types responsible for their stabilization. Our findings show that electrostatic and exchange energies are responsible for heterocluster stabilization, and also suggest a mutual weakening among hydrogen bonds when more than three water molecules are present. All described results are complementary and suggest a structural and energetic explanation at the molecular level for the experimental molar ratio of 1:3 (DEC:H2O) for the DEC-water azeotrope. PMID:25786831

  16. Pressure Swing Batch Distillation for Homogeneous Azeotropic Separation

    Microsoft Academic Search

    J.-U. Repke; A. Klein; D. Bogle; G. Wozny

    2007-01-01

    The separation of the homogeneous azeotropic mixture acetonitrile\\/water by pressure swing distillation (PSD) is considered. In this work, the PSD is operated as a discontinuous (batch) process and two basic batch modes, regular and inverted, are investigated. The processes are analysed and a rigorous dynamic model for both batch PSD processes is formulated. The model takes a cold and empty

  17. Homogeneous azeotropic pressure swing distillation: Continuous and batch process

    Microsoft Academic Search

    Jens-Uwe Repke; Andreas Klein

    2005-01-01

    The separation of a binary homogeneous azeotropic mixture using pressure swing distillation will be analysed on the example of acetonitrile\\/water. Two different processes are considered: the continuous heat- and mass-integrated process and the inverted batch process. For both processes a model is developed and experimental data are given. In the paper the potential of the pressure swing distillation for the

  18. Separation of Azeotropic Dimethylcarbonate\\/Methanol Mixtures by Pervaporation: Sorption and Diffusion Behaviors in the Pure and Nano Silica Filled PDMS Membranes

    Microsoft Academic Search

    Lei Wang; Xiaolong Han; Jiding Li; Xia Zhan; Jian Chen

    2011-01-01

    In this paper, polydimethylsiloxane and hydrophobic nano-silica filled polydimethylsiloxane membranes were prepared and employed in dimethylcarbonate (DMC) removing from DMC\\/methanol mixture via pervaporation. The sorption and diffusion behavior of the binary molecule were discussed separately to provide qualitative estimation of the PV performance in both membranes. Compared with polydimethylsiloxane membrane, hydrophobic nano-silica filled polydimethylsiloxane membranes had a little lower sorption

  19. Supercritical separation process for complex organic mixtures

    DOEpatents

    Chum, H.L.; Filardo, G.

    1990-10-23

    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 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. 1 fig.

  20. Homogeneous azeotropic distillation in an energy- and mass-integrated pressure swing column system

    Microsoft Academic Search

    Jens-Uwe Repke; Andreas Klein; Florian Forner

    2004-01-01

    The separation of a homogeneous azeotropic mixture using the pressure swing distillation process is insufficient researched and therefore industrial applications are limited. The process performance of a heat- and mass-integrated pressure swing distillation column system to separate an acetonitril\\/water mixture is analysed in the scope of this paper. Different control structures are developed and compared by using a rigorous dynamic

  1. Azeotropic distillation in a middle vessel batch column. 1: Model formulation and linear separation boundaries

    Microsoft Academic Search

    Weiyang Cheong; Paul I. Barton

    1999-01-01

    A mathematical model for the middle vessel batch distillation column (MVC) is developed using the concept of warped time analysis and used to study the qualitative dynamics of the MVC when it is used to separate multicomponent azeotropic mixtures. A limiting analysis is then developed for a MVC with an infinite number of trays, operated under infinite reflux\\/reboil ratios, under

  2. Azeotropic distillation in a middle vessel batch column. 2: Nonlinear separation boundaries

    SciTech Connect

    Cheong, W.; Barton, P.I. [Massachusetts Inst. of Tech., Cambridge, MA (United States)] [Massachusetts Inst. of Tech., Cambridge, MA (United States)

    1999-04-01

    On the basis of the analytical tools developed for the middle vessel column (MVC) operated under limiting conditions, analysis of the qualitative dynamics of the MVC in separating an azeotropic mixture is extended to the more realistic case in which the separation boundaries are nonlinear. The differences between batch stripper pot composition boundaries and batch rectifier pot composition being able to cross these pot composition boundaries. On the basis of these insights, operating procedures are developed in which ternary azeotropic mixtures of acetone, benzene, and chloroform can be separated into their constituent pure components, a separation not achievable with either the batch stripper or the batch rectifier. The operating procedures suggested for separating the ternary azeotropic mixture of acetone, benzene, and chloroform in the MVC are then shown to be the time analogues of sequences of continuous distillation columns that achieve the same separation. On the basis of this space-time analogy, further analogies are developed between the MVC and a continuous column, and it is postulated that many complex separations currently achieved with sequences of continuous columns can also be achieved with a single MVC. Thus, the MVC represents the ultimate multipurpose solvent recovery technology, as it can handle, in a batch multipurpose mode. separations that will otherwise require a dedicated continuous distillation sequence. Finally, the characteristics of perfect MVC batch entrainers, which allow the complete separation of any azeotrope into its constituent pure components in a single MVC, are discussed.

  3. Concentration of light organic compounds from dilute aqueous solutions by adsorption on bound silicalite

    E-print Network

    Flores, Kathryn Louise

    1989-01-01

    . 6 '7o ethanol at atmospheric pressure. Azeotropic, extractive and vacuum distillation techniques have been developed to purify mixtures beyond the azeotropic concentration. 2. 1. 1 Azeotropic Distillation Azeotropic distillation uses a, solvent... for several entrainers. Benzene, pentane and diethyl ether were the entrainers considered. s Pentane was found to consume less energy in the dehydration of azeotropic ethanol than either benzene or diethyl ether. 2. 1. 2 Extractive Distillation A solvent...

  4. Azeotropy in the natural and synthetic refrigerant mixtures

    Microsoft Academic Search

    Sergey Artemenko; Victor Mazur

    2007-01-01

    A novel approach for the prediction of azeotrope formation in a mixture that does not require vapour–liquid equilibrium calculations is developed. The method employs neural networks and global phase diagram methodologies to correlate azeotropic data for binary mixtures based only on critical properties and acentric factor of the individual components in refrigerant mixtures. Analytical expressions to predict azeotropy and double

  5. Fabrication of alumina nanofibers by precipitation reaction combined with heterogeneous azeotropic distillation process

    Microsoft Academic Search

    Xun Liu; Zhiguo Wu; Tianyou Peng; Ping Cai; Hongjin Lv; Wenlong Lian

    2009-01-01

    ?-Alumina nanofibers have been prepared from a precipitation reaction between aluminum ammonium sulfate and Baker's salt solutions followed by a heterogeneous azeotropic distillation process with N-butanol and calcination at 1173K. Experimental results indicate that the terminal pH value of the reaction mixture should be kept at 7.00–8.00 in order to obtain ?-Al2O3 nanofibers. The resulting spherical aluminum hydrate precipitates are

  6. (CH3)3SiCl/SiCl4 azeotrope grows superhydrophobic nanofilaments.

    PubMed

    Gao, Lichao; McCarthy, Thomas J

    2008-01-15

    We describe the vapor-phase reaction (at room temperature and 40-45% relative humidity) of silicon wafers with the azeotropic mixture of trimethylchlorosilane and tetrachlorosilane. Water contact angle analysis indicates that surfaces become nearly perfectly hydrophobic (thetaA/thetaR > or =176 degrees/> or =176 degrees) after 2 min of reaction. SEM analysis at various reaction times shows the growth of nanofilaments with diameters of approximately 30 nm. X-ray photoelectron spectroscopy of oxidized titanium surfaces that were exposed to the azeotrope vapor indicates that the product is derived from a approximately 10:1 ratio of SiCl4 and (CH3)3SiCl. A mechanism for filament growth is proposed. PMID:18088148

  7. Engineering Organic/inorganic hybrids comprise a mixture of oxide

    E-print Network

    Chemical Engineering Abstract Organic/inorganic hybrids comprise a mixture of oxide particles examine the current status of using organic/inorganic hybrids in fabrication of solid oxide fuel cells of potential applications in coatings, fuel cells, solar cells, and sensors. Organic amino (-NH2) silane

  8. Acoustic properties of organic acid mixtures in water

    NASA Technical Reports Server (NTRS)

    Macavei, I.; Petrisor, V.; Auslaender, D.

    1974-01-01

    The variation of the rate of propagation of ultrasounds in organic acid mixtures in water points to structural changes caused by interactions that take place under conditions of thermal agitation, at different acid concentrations. At the same time, a difference is found in the changes in velocity as a function of the length of the carbon chain of the acids in the mixture as a result of their effect on the groups of water molecules associated by hydrogen bonds.

  9. ACUTE TOXICITY OF ORGANIC CHEMICAL MIXTURES TO THE FATHEAD MINNOW

    EPA Science Inventory

    The acute joint toxicity of industrial organic chemicals to the fathead minnow was determined for binary and equitoxic multiple chemical mixtures. Results from binary tests were used to define isobole diagrams. The degree of joint toxic action was determined among 27 chemicals fr...

  10. Separation of Liquid Mixtures by Pervaporation

    Microsoft Academic Search

    B. D. Gupta; A. K. Mukherjee

    1990-01-01

    Separation of various mixtures, especially liquid mixtures, is a very necessary unit operation in industry. A large number of such techniques are available, such as distillation, adsorption, liquid-liquid extraction, and fractional crystalization [l]. The development of this type of technology became necessary to effect separation of azeotropic liquid mixtures. For liquid mixtures having components with similar boiling ranges, however, such

  11. ATR spectra on boundary with mixture containing organic substances

    NASA Astrophysics Data System (ADS)

    Schelokov, R. V.; Yatsishen, V. V.

    2005-02-01

    The problem of not destroying diagnostics and dosing of radiation at laser therapy is one of important in medicine. Therefore the purpose of our work is development of method ATR for diagnostics and researches in biomedicine. In this work as objects of consideration were: a mixture of nicotine with water, a mixture of an ascorbic acid with water and surface lesions of an eye cornea by a herpes virus. Results of our consideration are the ATR spectra defined at different concentration of organic substances and virions.

  12. Practical residue curve map analysis applied to solvent recovery in non-ideal binary mixtures by batch distillation processes

    Microsoft Academic Search

    Vincent Gerbaud; Joulia Xavier; Rodriguez-Donis Ivonne; Baudouin Olivier; Rosemain Olivier; Vacher Alain; Castelain Pierre

    2006-01-01

    Batch distillation inherent advantages have initiated recent search for process feasibility rules enabling the separation of azeotropic or difficult zeotropic binary mixtures thanks to the addition of an entrainer. A systematic procedure enabling to find suitable process and eventually suitable entrainer for the separation of zeotropic or azeotropic binary mixture is described. It brings together into practical use batch distillation

  13. Azeotropic distillation in a middle vessel batch column. 3: Model validation

    SciTech Connect

    Cheong, W.; Barton, P.I. [Massachusetts Inst. of Tech., Cambridge, MA (United States)] [Massachusetts Inst. of Tech., Cambridge, MA (United States)

    1999-04-01

    A dimensional time model of the middle vessel batch distillation column (MVC) is developed in the ABACUSS process modeling environment, and simulations are conducted to validate the theoretical insights developed for the operation of the MVC based on a warped time model of the MVC. The qualitative dynamics of the MVC operated in the presence of linear separation boundaries are validated via simulations conducted on the ternary azeotropic mixture of acetone, chloroform, and methanol. It is also shown via simulation that the separation results obtained from a column with significant but reasonable amounts of holdup on the trays are not significantly different from a column in which holdup in the trays is assumed to be negligible. Theoretical operating policies for separating the azeotrope of acetone and chloroform using benzene as a batch entrainer are also validated using the ABACUSS model. Finally, the authors explore the advantages and disadvantages of different feasible operating policies for separating a mixture of acetone, benzene, and chloroform completely into its constituent pure components.

  14. Adsorbate shape selectivity: Separation of the HF/134a azeotrope over carbogenic molecular sieve

    SciTech Connect

    Hong, A.; Mariwala, R.K.; Kane, M.S.; Foley, H.C. [Univ. of Delaware, Nework, DE (United States)

    1995-03-01

    Experimental evidence is provided for adsorptive shape selectivity in the separation of the azeotrope between HF and 1,1,1,2-tetrafluoroethane (134a) over pyrolyzed poly(furfuryl alcohol)-derived carbogenic molecular sieve (PPFA-CMS). The separation can be accomplished over coconut charcoal or Carbosieve G on the basis of the differences in the extent of equilibrium adsorption of HF and 134a. On these adsorbents 134a is more strongly bound than HF, thus it elutes much more slowly from the bed. The heat of adsorption for 134a in the vicinity of 200 C on Carbosieve G is {approximately}8.8 kcal/mol. In contrast, when the same azeotropic mixture is separated over PPFA-CMS prepared at 500 C, 134a is not adsorbed. As a result 134a elutes from the bed first, followed by HF. The reversal is brought about by the narrower pore size and pore size distribution of the PPFA-CMS versus that for Carbosieve G. Thus the separation over PPFA-CMS is an example of adsorbate shape selectivity and represents a limiting case of kinetic separation.

  15. Azeotropic Distillation as a Technique for Emulsion Size Reduction

    E-print Network

    Petta, Jason

    : A solvent with HA Boiling point with water Heptane or Hexane Low vapor pressure viscosifying oil Distillation setup/ process -Found the Heterogeneous Azeotropic Distillation Boiling points for Water% Solvent Initial Size(µm) Size after one hour(µm) Boiling point Range (°C) 25% PB320 Span 80 75% hex. 28

  16. Adsorption and desorption of binary mixtures of volatile organic contaminants on soil

    E-print Network

    Guo, Yang

    1995-01-01

    BET type 11 isotherms, which indicates multilayer adsorption on soil. The heats of adsorption indicate physical adsorption. Competitive adsorption of organic mixtures on soil was assessed by measuring the adsorption equilibria of binary mixtures...

  17. Toxicity assessment of organic contaminants: evaluation of mixture effects in model industrial mixtures using 2n full factorial design.

    PubMed

    Parvez, Shahid; Venkataraman, Chandra; Mukherji, Suparna

    2008-10-01

    Toxic organic chemicals present in industrial effluents were screened to design mixtures for examining the significant main and interaction effects among mixture components. A set of five four-component mixtures was selected by examining effluents from organic chemical, textile-dye, pulp-paper and petroleum refinery industries. The screening was based on their discharge, solubility, toxicity and volatility. A 2(n) full factorial approach was used in designing the mixtures, containing components at two dose levels, EC(10)(-) and EC(40)(+). Each mixture resulted in 16 combinations. Mixture toxicity was measured using the Vibrio fischeri bioluminescence inhibition assay. The main effects and binary, ternary and quaternary interaction effects were determined and the significance of effects was evaluated using normal order score and multifactor ANOVA. The organic chemicals retained after screening included, acetaldehyde, aniline, n-butanol, p-cresol, catechol, ethylbenzene, naphthalene, phenol, 1,2,4 trimethylbenzene and o-xylene. In all mixtures, the magnitude of main effects was more significant than the interaction effects. The trend in the main effect of components in any mixture was affected by the trends in the physico-chemical properties of the components, i.e., partition coefficient, molecular size and polarity. In some mixtures, a component with significantly higher concentration and significantly lower toxicity was found to depict a relatively high main effect, as observed for acetaldehyde in mixture I and n-butanol in mixture III. Normal order score approach failed to identify the significant interaction effects that could be identified using multifactor ANOVA. In general, the binary interactions were more significant than the ternary and quaternary interactions. PMID:18789476

  18. Control of Meloidogyne incognita Using Mixtures of Organic Acids.

    PubMed

    Seo, Yunhee; Kim, Young Ho

    2014-12-01

    This study sought to control the root-knot nematode (RKN) Meloidogyne incognita using benign organo-chemicals. Second-stage juveniles (J2) of RKN were exposed to dilutions (1.0%, 0.5%, 0.2%, and 0.1%) of acetic acid (AA), lactic acid (LA), and their mixtures (MX). The nematode bodies were disrupted severely and moderately by vacuolations in 0.5% of MX and single organic acids, respectively, suggesting toxicity of MX may be higher than AA and LA. The mortality of J2 was 100% at all concentrations of AA and MX and only at 1.0% and 0.5% of LA, which lowered slightly at 0.2% and greatly at 0.1% of LA. This suggests the nematicidal activity of MX may be mostly derived from AA together with supplementary LA toxicity. MX was applied to chili pepper plants inoculated with about 1,000 J2, for which root-knot gall formations and plant growths were examined 4 weeks after inoculation. The root gall formation was completely inhibited by 0.5% MX and standard and double concentrations of fosthiazate; and inhibited 92.9% and 57.1% by 0.2% and 0.1% MX, respectively. Shoot height, shoot weight, and root weight were not significantly (P ? 0.05) different among all treatments and the untreated and non-inoculated controls. All of these results suggest that the mixture of the organic acids may have a potential to be developed as an eco-friendly nematode control agent that needs to be supported by the more nematode control experiments in fields. PMID:25506312

  19. Control of Meloidogyne incognita Using Mixtures of Organic Acids

    PubMed Central

    Seo, Yunhee; Kim, Young Ho

    2014-01-01

    This study sought to control the root-knot nematode (RKN) Meloidogyne incognita using benign organo-chemicals. Second-stage juveniles (J2) of RKN were exposed to dilutions (1.0%, 0.5%, 0.2%, and 0.1%) of acetic acid (AA), lactic acid (LA), and their mixtures (MX). The nematode bodies were disrupted severely and moderately by vacuolations in 0.5% of MX and single organic acids, respectively, suggesting toxicity of MX may be higher than AA and LA. The mortality of J2 was 100% at all concentrations of AA and MX and only at 1.0% and 0.5% of LA, which lowered slightly at 0.2% and greatly at 0.1% of LA. This suggests the nematicidal activity of MX may be mostly derived from AA together with supplementary LA toxicity. MX was applied to chili pepper plants inoculated with about 1,000 J2, for which root-knot gall formations and plant growths were examined 4 weeks after inoculation. The root gall formation was completely inhibited by 0.5% MX and standard and double concentrations of fosthiazate; and inhibited 92.9% and 57.1% by 0.2% and 0.1% MX, respectively. Shoot height, shoot weight, and root weight were not significantly (P ? 0.05) different among all treatments and the untreated and non-inoculated controls. All of these results suggest that the mixture of the organic acids may have a potential to be developed as an eco-friendly nematode control agent that needs to be supported by the more nematode control experiments in fields. PMID:25506312

  20. Bruges, Belgium Self Organization in Mixture Densities of

    E-print Network

    Kurimo, Mikko

    state is a unique mixture of the Gaussian densities. The mixture densities are trained by segmental Typewriter'' [3] and its later developments have several years been a test bench for the SOM and LVQ algo

  1. Kolbe electrolysis of mixtures of aliphatic organic acids

    SciTech Connect

    Levy, P.F.; Cheng, L.K.; Sanderson, J.E.

    1984-04-01

    Kolbe electrolysis of mixtures of n-butanoic with n-hexanoic acid and propranoic with n-hexanoic acid have been performed in aqueous solution at a smooth platinum anode. Typically, hexane production by the oxidation of butanoic acid, or butane production from propanoic acid, in aqueous solution is not observed to exceed a few percent In the current work, significant increases of these products were observed. In addition, a substantial fraction of the remaining C/sub 3/ or C/sub 4/ acids reacted were converted to mixed alkane dimers with hexanoic acid. These results are interpreted by a model in which n-hexanoic acid and its various oxidation products form a lipophilic layer at the anode surface which provides an environment where further oxidation to carbonium ions is disfavored. This model has been suggested previously to explain pressure effects on Kolbe electrolysis. This observation supports the feasibility of producing mixed linear alkanes for use as fuels and chemicals from mixed organic acids which may be produced by anaerobic fermentation of organic matter.

  2. Behavioural evaluation of workers exposed to mixtures of organic solvents.

    PubMed

    Maizlish, N A; Langolf, G D; Whitehead, L W; Fine, L J; Albers, J W; Goldberg, J; Smith, P

    1985-09-01

    Reports from Scandinavia have suggested behavioural impairment among long term workers exposed to solvents below regulatory standards. A cross sectional study of behavioural performance was conducted among printers and spray painters exposed to mixtures of organic solvents to replicate the Scandinavian studies and to examine dose-response relationships. Eligible subjects consisted of 640 hourly workers from four midwestern United States companies. Of these, 269 responded to requests to participate and 240 were selected for study based on restrictions for age, sex, education, and other potentially confounding variables. The subjects tested had been employed on average for six years. Each subject completed an occupational history, underwent a medical examination, and completed a battery of behavioural tests. These included the Fitts law psychomotor task, the Stroop colour-word test, the Sternberg short term memory scanning test, the short term memory span test, and the continuous recognition memory test. Solvent exposure for each subject was defined as an exposed or non-exposed category based on a plant industrial hygiene walk-through and the concentration of solvents based on an analysis of full shift personal air samples by gas chromatography. The first definition was used to maintain consistency with Scandinavian studies, but the second was considered to be more accurate. The average full shift solvent concentration was 302 ppm for the printing plant workers and 6-13 ppm for the workers at other plants. Isopropanol and hexane were the major components, compared with toluene in Scandinavian studies. Performance on behavioural tests was analysed using multiple linear regression with solvent concentration as an independent variable. Other relevant demographic variables were also considered for inclusion. No significant (p greater than 0.05) relation between solvent concentration and impairment on any of the 10 behavioural variables was observed after controlling for confounding variables. Exposed/non-exposed comparisons showed a significantly poorer digit span among those exposed, but this has not been generally reported in the Scandinavian studies. The medical examination showed no abnormalities of clinical significance. The inability to replicate the findings of the Scandinavian studies could have been due to the shortness of the duration of workers' exposure, the type of solvents in the mixtures, use of different behavioural tests, or to selection factors. PMID:3876109

  3. Preparation and characterization of nanoscale Y-TZP powder by heterogeneous azeotropic distillation

    Microsoft Academic Search

    Haibo Qiu; Lian Gao; Chude Feng; Jingkun Guo; Dongsheng Yan

    1995-01-01

    A heterogeneous azeotropic distillation process was effectively used to dehydrate hydrous zirconia and therefore prevent the formation of hard agglomerates in the preparation of nanoscale zirconia powder. The mechanism of azeotropic distillation to prevent hard agglomerate from forming was studied by investigating the interaction of hydrous zirconia with n-butanol. The prepared powder was sintered to 99.5% of theoretical density by

  4. Fouling and cleaning of RO membranes fouled by mixtures of organic foulants simulating wastewater effluent

    Microsoft Academic Search

    Wui Seng Ang; Alberto Tiraferri; Kai Loon Chen; Menachem Elimelech

    2011-01-01

    The fouling and subsequent cleaning of RO membranes fouled by a mixture of organic foulants simulating wastewater effluent has been systematically investigated. The organic foulants investigated included alginate, bovine serum albumin (BSA), Suwannee River natural organic matter, and octanoic acid, representing, respectively, polysaccharides, proteins, humic substances, and fatty acids, which are ubiquitous in effluent organic matter. After establishing the fouling

  5. Retention capacity of an organic bio-mixture against different mixtures of fungicides used in vineyards

    Microsoft Academic Search

    Elga Monaci; Laura Coppola; Cristiano Casucci; Piero Perucci; Costantino Vischetti

    2009-01-01

    A laboratory experiment was carried out to test the efficiency of a bio-mixture made up of pruning residues at two (PR2) and five (PR5) years of composting and wheat straw (STW) in the biological cleaning of water contaminated by different mixtures of fungicides usually employed in vineyards. The experiment was conducted and reproduced at a scale of 1:100 of operating

  6. Supercritical extraction of organic mixtures from soil-water slurries

    E-print Network

    Green, Lynda Ann

    1994-01-01

    Supercritical C02was used to extract orgamc rruxtures from soil-water slurries. The extent of extraction and the equilibrium distribution of the mixture and of the individual components were determined. A single stage batch vessel was used...

  7. PROCEDURES FOR DERIVING EQUILIBRIUM PARTITIONING BENCHMARKS (ESBS) FOR THE PROTECTION OF BENTHIC ORGANISM: PAH MIXTURES

    EPA Science Inventory

    This equilibrium partitioning sediment benchmark (ESB) document describes procedures to derive concentrations of PAH mixtures in sediment which are protective of the presence of benthic organisms. The equilibrium partitioning (EqP) approach was chosen because it accounts for t...

  8. Solubilities of hydrophobic compounds in aqueous-organic solvent mixtures.

    PubMed

    Nyssen, G A; Miller, E T; Glass, T F; Quinn, C R; Underwood, J; Wilson, D J

    1987-07-01

    Solubilities of several hydrophobic organic substances (paradichlorobenzene, endrin, naphthalene, and dibutyl phthalate) in aqueous solutions containing up to 0.10 mole fraction of common alcohols and ketones, were measured by gas chromatography. The solubilities are significantly increased by the alcohols and ketones. The results are interpreted in terms of the association of n molecules of alcohol or ketone with each hydrophobic organic molecule. Values of n and the equilibrium constant for this association are reported for each hydrophobic organic-alcohol and organic-ketone combination. The implications of these results for the disposal of toxic wastes by landfilling is discussed. PMID:24254096

  9. Isothermal vapor–liquid equilibria for mixtures of 4-methoxyphenol, catechol, and p-cresol

    Microsoft Academic Search

    Shou-Ming Hwang; Ming-Jer Lee; Ho-mu Lin

    2000-01-01

    Isothermal vapor–liquid equilibrium data are measured with a static apparatus for the binary and ternary mixtures composed of 4-methoxyphenol, catechol (1,2-dihydroxybenzene ), and p-cresol (4-methylphenol) at temperatures ranging from 423.15 to 453.15K. While minimum pressure azeotropes are exhibited in 4-methoxyphenol+catechol, no azeotropes are found in the rest of the systems. The new binary data are correlated with the Wilson, the

  10. Nature and prevalence of non-additive toxic effects in industrially relevant mixtures of organic chemicals.

    PubMed

    Parvez, Shahid; Venkataraman, Chandra; Mukherji, Suparna

    2009-06-01

    The concentration addition (CA) and the independent action (IA) models are widely used for predicting mixture toxicity based on its composition and individual component dose-response profiles. However, the prediction based on these models may be inaccurate due to interaction among mixture components. In this work, the nature and prevalence of non-additive effects were explored for binary, ternary and quaternary mixtures composed of hydrophobic organic compounds (HOCs). The toxicity of each individual component and mixture was determined using the Vibrio fischeri bioluminescence inhibition assay. For each combination of chemicals specified by the 2(n) factorial design, the percent deviation of the predicted toxic effect from the measured value was used to characterize mixtures as synergistic (positive deviation) and antagonistic (negative deviation). An arbitrary classification scheme was proposed based on the magnitude of deviation (d) as: additive (< or =10%, class-I) and moderately (10< d < or =30 %, class-II), highly (30< d < or =50%, class-III) and very highly (>50%, class-IV) antagonistic/synergistic. Naphthalene, n-butanol, o-xylene, catechol and p-cresol led to synergism in mixtures while 1, 2, 4-trimethylbenzene and 1, 3-dimethylnaphthalene contributed to antagonism. Most of the mixtures depicted additive or antagonistic effect. Synergism was prominent in some of the mixtures, such as, pulp and paper, textile dyes, and a mixture composed of polynuclear aromatic hydrocarbons. The organic chemical industry mixture depicted the highest abundance of antagonism and least synergism. Mixture toxicity was found to depend on partition coefficient, molecular connectivity index and relative concentration of the components. PMID:19344929

  11. Azeotropic distillation in a middle vessel batch column. 1: Model formulation and linear separation boundaries

    SciTech Connect

    Cheong, W.; Barton, P.I. [Massachusetts Inst. of Tech., Cambridge, MA (United States)] [Massachusetts Inst. of Tech., Cambridge, MA (United States)

    1999-04-01

    A mathematical model for the middle vessel batch distillation column (MVC) is developed using the concept of warped time analysis and used to study the qualitative dynamics of the MVC when it is used to separate multicomponent azeotropic mixtures. A limiting analysis is then developed for a MVC with an infinite number of trays, operated under infinite reflux/reboil ratios, under the assumption of linear separation boundaries. It is determined that, under limiting conditions, the distillate product drawn from the MVC is given by the {alpha} limit set of the MVC still pot composition, while the bottoms product drawn from the MVC is given by the {omega} limit set of the MVC still pot composition. The net product composition is determined by taking a convex combination of the two products. The notions of steering the still pot composition, the vector cone of possible motion for the still pot composition, and the equivalency of the MVC to the combined operation of a batch rectifier and a stripper are also explored. The definition of batch distillation regions for the MVC operated at a given value of the middle vessel parameter {lambda}, and the bifurcation of these regions with the variation of {lambda}, are investigated. Lastly, a mathematical model incorporating the concept of warped time is developed for a multivessel column. The MVC can be viewed as a specific case of the multivessel column.

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

    EPA Science Inventory

    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...

  13. ODOR AND IRRITATION EFFECTS OF A VOLATILE ORGANIC COMPOUND MIXTURE

    EPA Science Inventory

    Human exposure to volatile organic compounds elicits a variety ofsymptoms, many of which are thought to be mediated by the olfactoryand trigeminal systems. his report describes evidence indicatingthat perceived odor intensity diminishes during prolonged exposure,whearas irritatin...

  14. Passivity and breakdown of carbon steel in organic solvent mixtures of propylene carbonate and dimethoxyethane

    SciTech Connect

    Shifler, D.A. [Naval Surface Warfare Center, West Bethesda, MD (United States). Carderock Div.; Kruger, J. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Materials Science and Engineering; Moran, P.J. [Naval Academy, Annapolis, MD (United States). Dept. of Mechanical Engineering

    1998-07-01

    The passivity and breakdown of passivity of 1018 carbon steel in propylene carbonate (PC) and 1,2-dimethoxyethane (DME) mixtures with 0.5 molar lithium hexafluoroarsenate supporting electrolyte were examined via several electrochemical and surface analytical methods. The PC-DME/0.5 M LiAsF{sub 6} mixtures ranged from 10 to 90 mol % PC. The results from the PC/DME mixtures were compared to passivating mechanisms found in pure PC and DME solutions. In PC-rich mixtures, the breakdown of passivity occurred near the oxidation potentials of either organic solvent. Premature breakdown of the carbon steel in PC-DME mixtures occurred at sulfide inclusions as was observed earlier in PC/0.5 M LiAsF{sub 6} solutions although passive films attempted to form at these inclusion sites in mixtures containing at least 10 mol % DME. As the DME content increased in the PC-DME mixtures, the passive films formed on bare steel surfaces possessed an increasing polymer film character. In 50 and 70 mol % DME solutions nonprotective polymer films were formed. The nonprotective nature of these films indicated that PC passivation mechanisms competed and interfered with the DME mechanism of electropolymerized film formation. Only in 10 mol % PC-90 mol % DME mixtures were protective electropolymerized films formed on 1018 carbon steel.

  15. FLY ASH ORGANIC BYPRODUCT MIXTURE AS SOIL AMENDMENTS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Greenhouse studies were conducted to assess the potential of fly ash-organic waste co-disposal to enhance crop production. Two pot experiments, one using Sorghum Sudangrass (Sorghum vulgaris) and other using Collard greens (Brassica olreraceae) were conducted under greenhouse conditions. In addition...

  16. Dependences between the boiling point of binary aqueous-organic mixtures and their composition

    NASA Astrophysics Data System (ADS)

    Preobrazhenskii, M. P.; Rudakov, O. B.

    2015-01-01

    The optimum three-parametric regression basis set that reflects the properties of permutation symmetry and takes into account the specificity of isobars of aqueous-organic mixtures is constructed. The optimum algorithm for the calculation of the regression parameters of the boiling point isobars is proposed. The parameters are calculated for a series of systems. The accuracy of the method proposed for the regression description of the dependence of the boiling point of binary aqueous-organic mixtures on the composition is determined by empirical inaccuracies and is sufficient for the most part of practical applications. Methods for increasing the accuracy of the regression description of equilibrium homogeneous systems are formulated.

  17. ACTION CONCENTRATION FOR MIXTURES OF VOLATILE ORGANIC COMPOUNDS (VOC) & METHANE & HYDROGEN

    SciTech Connect

    MARUSICH, R.M.

    2006-07-10

    Waste containers may contain volatile organic compounds (VOCs), methane, hydrogen and possibly propane. These constituents may occur individually or in mixtures. Determining if a waste container contains a flammable concentration of flammable gases and vapors (from VOCs) is important to the safety of the handling, repackaging and shipping activities. This report provides the basis for determining the flammability of mixtures of flammable gases and vapors. The concentration of a mixture that is at the lowest flammability limit for that mixture is called the action concentration. The action concentration can be determined using total VOC concentrations or actual concentration of each individual VOC. The concentrations of hydrogen and methane are included with the total VOC or individual VOC concentration to determine the action concentration. Concentrations below this point are not flammable. Waste containers with gas/vapor concentrations at or above the action concentration are considered flammable.

  18. PRENEOPLASTIC TRANSFORMATION OF RESPIRATORY EPITHELIAL CELLS BY COMPLEX ORGANIC MIXTURES IN A CLONAL ASSAY

    EPA Science Inventory

    In the study complex organic mixtures that were extracts of particulate emissions from 3 heating sources were tested for the presence of agents that induce preneoplastic transformation of rat tracheal epithelial (RTE) cells in an in vitro clonal assay. The samples were derived fr...

  19. Molecular identification of organic compounds in atmospheric complex mixtures and relationship to atmospheric chemistry and sources.

    PubMed Central

    Mazurek, Monica A

    2002-01-01

    This article describes a chemical characterization approach for complex organic compound mixtures associated with fine atmospheric particles of diameters less than 2.5 m (PM2.5). It relates molecular- and bulk-level chemical characteristics of the complex mixture to atmospheric chemistry and to emission sources. Overall, the analytical approach describes the organic complex mixtures in terms of a chemical mass balance (CMB). Here, the complex mixture is related to a bulk elemental measurement (total carbon) and is broken down systematically into functional groups and molecular compositions. The CMB and molecular-level information can be used to understand the sources of the atmospheric fine particles through conversion of chromatographic data and by incorporation into receptor-based CMB models. Once described and quantified within a mass balance framework, the chemical profiles for aerosol organic matter can be applied to existing air quality issues. Examples include understanding health effects of PM2.5 and defining and controlling key sources of anthropogenic fine particles. Overall, the organic aerosol compositional data provide chemical information needed for effective PM2.5 management. PMID:12634131

  20. Lanolin-derived lipid mixtures mimic closely the lipid composition and organization of vernix caseosa lipids

    Microsoft Academic Search

    Robert Rissmann; Marion H. M. Oudshoorn; Elise Kocks; Wim E. Hennink; Maria Ponec; Joke A. Bouwstra

    2008-01-01

    The aim of the present study was to use semi-synthetic lipid mixtures to mimic the complex lipid composition, organization and thermotropic behaviour of vernix caseosa (VC) lipids. As VC shows multiple protecting and barrier supporting properties before and after birth, it is suggested that a VC substitute could be an innovative barrier cream for barrier deficient skin. Lanolin was selected

  1. A New Reverse Wormlike Micellar System: Mixtures of Bile Salt and Lecithin in Organic Liquids

    E-print Network

    Raghavan, Srinivasa

    A New Reverse Wormlike Micellar System: Mixtures of Bile Salt and Lecithin in Organic Liquids Shih amounts to solutions of the phospholipid lecithin. Previous recipes for reverse wormlike micelles have and promote the longitudinal aggregation of lecithin molecules into reverse micellar chains. The formation

  2. Optical Properties of Fluorescent Mixtures: Comparing Quantum Dots to Organic Dyes

    ERIC Educational Resources Information Center

    Hutchins, Benjamin M.; Morgan, Thomas T.; Ucak-Astarlioglu, Mine G.; Wlilliams, Mary Elizabeth

    2007-01-01

    The study describes and compares the size-dependent optical properties of organic dyes with those of semiconductor nanocrystals or quantum dots (QDs). The analysis shows that mixtures of QDs contain emission colors that are sum of the individual QD components.

  3. Adsorptive Drying of Organic Liquids- An Update 

    E-print Network

    Joshi, S.; Humphrey, J. L.; Fair, J. R.

    1986-01-01

    Removal of small amounts of water from organic liquids is normally handled by adsorption or by azeotropic distillation. The latter method is well documented and analysis or design is straightforward so long as the ...

  4. Methods of analysis for complex organic aerosol mixtures from urban emission sources of particulate carbon

    SciTech Connect

    Mazurek, M.A. (Brookhaven National Lab., Upton, NY (USA)); Hildemann, L.M. (Stanford Univ., CA (USA). Dept. of Civil Engineering); Cass, G.R.; Rogge, W.F. (California Inst. of Tech., Pasadena, CA (USA). Dept. of Environmental Engineering Science); Simoneit, B.R.T. (Oregon State Univ., Corvallis, OR (USA). Coll. of Oceanography)

    1990-04-01

    Extractable organic compounds having between 6 to 40 carbon atoms comprise an important mass fraction of the fine particulate matter samples from major urban emission sources. Depending on the emission source type, this solvent-soluble fraction accounts for <20% to 100% of the total organic aerosol mass, as measured by quantitative high-resolution has chromatography (HRGC) with flame ionization detection. In addition to total extract quantitation, HRGC can be applied to further analyses of the mass distributions of elutable organics present in the complex aerosol extract mixtures, thus generating profiles that serve as fingerprints'' for the sources of interest. This HRGC analytical method is applied to emission source samples that contain between 7 to 12,000 {mu}g/filter organic carbon. It is shown to be a sensitive technique for analysis of carbonaceous aerosol extract mixtures having diverse mass loadings and species distributions. This study describes the analytical chemical methods that have been applied to: the construction of chemical mass balances based on the mass of fine organic aerosol emitted for major urban sources of particulate carbon; and the generation of discrete emission source chemical profiles derived from chromatographic characteristics of the organic aerosol components. 21 refs., 1 fig., 2 tabs.

  5. Energy and exergy analysis of new refrigerant mixtures in an Organic Rankine Cycle for low temperature power generation

    Microsoft Academic Search

    S. M. Sami

    2010-01-01

    This paper presents and discusses the performance of environmentally-friendly refrigerant mixtures in an Organic Rankine Cycle (ORC) for power generation. The performance has been compared at low and medium waste heat temperatures to other organic and non-organic fluids.The refrigerant mixtures boil at extremely low temperatures and are capable of efficiently capturing waste heat at temperatures less than 27°C (80°F). The

  6. Pervaporative removal of organics from water using hydrophobic membranes. Binary mixtures

    SciTech Connect

    Kujawski, W.

    2000-01-01

    Results of pervaporation experiments are presented for the separation of several polar and nonpolar organic solvents from their aqueous solutions. Three membranes were evaluated: a polydimethylsiloxane (PERVAP-1060) membrane, a PDMS ZSM-5 zeolite filled (PERVAP-1070) membrane, and a poly(ether-block-amide) (PEBAX-4033) membrane. The effect of feed composition on flux and selectivity was also investigated. Performance parameters of a given membrane depended both on the kind of the organic solvent and the feed composition. The PERVAP-1070 membrane exhibited the highest selectivity with a separation factor over 900 in contact with a water-butyl acetate mixture. Polar solvents like methanol were also preferentially separated from aqueous solutions, but the separation factors were close to those obtained from liquid-vapor equilibria data. Permeate fluxes of organics increased with increasing feed concentration. Synergetic effects between water and organics fluxes were also observed.

  7. Annual and seasonal changes in production and composition of grazed clover-grass mixtures in organic farming

    Microsoft Academic Search

    Eeva Kuusela

    2004-01-01

    A grazed field experiment based on a randomised block design was conducted in Eastern Finland to evaluate the potential of alsike clover (Trifoliun hybridum L.), red clover (Trifolium pratense L.) and white clover (Trifolium repens L.) to support herbage production from clover-grass mixtures under organic farming practices. The effect of seed mixture (alsike clover, red clover, white clover, white and

  8. Laboratory appraisal of organic carbon changes in mixtures made with different inorganic wastes.

    PubMed

    Arbestain, M Camps; Ibargoitia, M L; Madinabeitia, Z; Gil, M V; Virgel, S; Morán, A; Pereira, R Calvelo; Macías, F

    2009-12-01

    Mixtures of organic and inorganic wastes were incubated to examine the changes in organic C (OC) contents. An anaerobic sludge and a CaO-treated aerobic sludge, with OC concentrations of 235 and 129 gkg(-1), were used. The inorganic wastes used - referred to as "conditioners" - were shot blasting scrap, fettling, Linz-Donawitz slag, foundry sand (FS), and fly ash from wood bark combustion (FA). The total OC (TOC) and KMnO(4)(-) oxidized OC were determined. DTA-TGA profiles and FTIR spectra were also obtained. Mixtures made with the FS contained significantly lower (P<0.05) amounts of TOC (45 gkg(-1)) than the rest of mixtures, which was attributed to the non-existence of reactive surfaces in the conditioner and the increased aeration induced by this material. Those made with FA contained significantly higher (P<0.05) amounts of TOC (170 gkg(-1)), which was attributed to: (i) the addition of an extra source of C - black carbon (BC) - in the FA, and (ii) the inhibition of mineralization from the compounds present in this conditioner (e.g., amorphous aluminosilicates, BC). The results highlight the importance of the characteristics of the conditioners on the fate of the OM originating from the sludges. PMID:19632821

  9. Enabling the identification, quantification, and characterization of organics in complex mixtures to understand atmospheric aerosols

    NASA Astrophysics Data System (ADS)

    Isaacman, Gabriel Avram

    Particles in the atmosphere are known to have negative health effects and important but highly uncertain impacts on global and regional climate. A majority of this particulate matter is formed through atmospheric oxidation of naturally and anthropogenically emitted gases to yield highly oxygenated secondary organic aerosol (SOA), an amalgamation of thousands of individual chemical compounds. However, comprehensive analysis of SOA composition has been stymied by its complexity and lack of available measurement techniques. In this work, novel instrumentation, analysis methods, and conceptual frameworks are introduced for chemically characterizing atmospherically relevant mixtures and ambient aerosols, providing a fundamentally new level of detailed knowledge on their structures, chemical properties, and identification of their components. This chemical information is used to gain insights into the formation, transformation and oxidation of organic aerosols. Biogenic and anthropogenic mixtures are observed in this work to yield incredible complexity upon oxidation, producing over 100 separable compounds from a single precursor. As a first step toward unraveling this complexity, a method was developed for measuring the polarity and volatility of individual compounds in a complex mixture using two-dimensional gas chromatography, which is demonstrated in Chapter 2 for describing the oxidation of SOA formed from a biogenic compound (longifolene: C15H24). Several major products and tens of substantial minor products were produced, but none could be identified by traditional methods or have ever been isolated and studied in the laboratory. A major realization of this work was that soft ionization mass spectrometry could be used to identify the molecular mass and formula of these unidentified compounds, a major step toward a comprehensive description of complex mixtures. This was achieved by coupling gas chromatography to high resolution time-of-flight mass spectrometry with vacuum ultraviolet (VUV) photo-ionization. Chapters 3 and 4 describe this new analytical technique and its initial application to determine the structures of unknown compounds and formerly unresolvable mixtures, including a complete description of the chemical composition of two common petroleum products related to anthropogenic emissions: diesel fuel and motor oil. The distribution of hydrocarbon isomers in these mixtures - found to be mostly of branched, cyclic, and saturated -- is described with unprecedented detail. Instead of measuring average bulk aerosol properties, the methods developed and applied in this work directly measure the polarity, volatility, and structure of individual components to allow a mechanistic understanding of oxidation processes. Novel characterizations of these complex mixtures are used to elucidate the role of structure and functionality in particle-phase oxidation, including in Chapter 4 the first measurements of relative reaction rates in a complex hydrocarbon particle. Molecular structure is observed to influence particle-phase oxidation in unexpected and important ways, with cyclization decreasing reaction rates by ~30% and branching increasing reaction rates by ~20-50%. The observed structural dependence is proposed to result in compositional changes in anthropogenic organic aerosol downwind of urban areas, which has been confirmed in subsequent work by applying the techniques described here. Measurement of organic aerosol components is extended to ambient environments through the development of instrumentation with the unprecedented capability to measure hourly concentrations and gas/particle partitioning of individual highly oxygenated organic compounds in the atmosphere. Chapters 5 and 6 describe development of new procedures and hardware for the calibration and analysis of oxygenates using the Semi-Volatile Thermal desorption Aerosol Gas chromatograph (SV-TAG), a custom instrument for in situ quantification of gas- and particle-phase organic compounds in the atmosphere. High time resolution measurement of oxygenated com

  10. Technical Note: Dissolved organic matter fluorescence - a finite mixture approach to deconvolve excitation-emission matrices

    NASA Astrophysics Data System (ADS)

    Butturini, A.; Ejarque, E.

    2013-09-01

    The analysis of the shape of excitation-emission matrices (EEMs) is a relevant tool for exploring the origin, transport and fate of dissolved organic matter (DOM) in aquatic ecosystems. Within this context, the decomposition of EEMs is acquiring a notable relevance. A simple mathematical algorithm that automatically deconvolves individual EEMs is described, creating new possibilities for the comparison of DOM fluorescence properties and EEMs that are very different from each other. A mixture model approach is adopted to decompose complex surfaces into sub-peaks. The laplacian operator and the Nelder-Mead optimisation algorithm are implemented to individuate and automatically locate potential peaks in the EEM landscape. The EEMs of a simple artificial mixture of fluorophores and DOM samples collected in a Mediterranean river are used to describe the model application and to illustrate a strategy that optimises the search for the optimal output.

  11. PROCEDURES FOR THE DERIVATION OF EQUILIBRIUM PARTITIONING SEDIMENT BENCHMARKS (ESBS) FOR THE PROTECTION OF BENTHIC ORGANISMS: PAH MIXTURES

    EPA Science Inventory

    This equilibrium partitioning sediment benchmark (ESB) document describes procedures to derive concentrations of PAH mixtures in sediment which are protective of the presence of benthic organisms. The equilibrium partitioning (EqP) approach was chosen because it accounts for the ...

  12. Natural Mixtures of Persistent Organic Pollutants (POP) Increase Weight Gain, Advance Puberty, and Induce Changes in Gene Expression Associated with Steroid Hormones and Obesity in Female Zebrafish

    Microsoft Academic Search

    Jan L. Lyche; Rasoul Nourizadeh-Lillabadi; Camilla Almaas; Benedicte Stavik; Vidar Berg; Janneche Utne Skåre; Peter Alestrøm; Erik Ropstad

    2010-01-01

    In the present study, developmental and reproductive effects of lifelong exposure to environmental relevant concentrations of two natural mixtures of persistent organic pollutants (POP) were investigated using classical and molecular methods in a controlled zebrafish model. The mixtures used were extracted from burbot (Lota lota) liver originating from freshwater systems in Norway: one mixture with high levels and one mixture

  13. Spectroscopic characterization of organic matter of a soil and vinasse mixture during aerobic or anaerobic incubation

    SciTech Connect

    Doelsch, Emmanuel [CIRAD, Environmental Risks of Recycling Research Unit, Aix-en-Provence, F-13545 (France)], E-mail: doelsch@cirad.fr; Masion, Armand [CEREGE, Aix-Marseille University, CNRS, CDF, IRD, Europole Mediterraneen de L'Arbois, BP 80, 13545 Aix-en-Provence (France); Cazevieille, Patrick [CIRAD Environmental Risks of Recycling Research Unit, TA 70/01, Avenue Agropolis, F-34 398, Montpellier Cedex 5 (France); Condom, Nicolas [29 bd Louis Blanc, F-34000 Montpellier (France)

    2009-06-15

    Mineralization potentials are often used to classify organic wastes. These methods involve measuring CO{sub 2} production during batch experiments, so variations in chemical compounds are not addressed. Moreover, the physicochemical conditions are not monitored during the reactions. The present study was designed to address these deficiencies. Incubations of a mixture of soil and waste (vinasse at 20% dry matter from a fermentation industry) were conducted in aerobic and anaerobic conditions, and liquid samples obtained by centrifugation were collected at 2 h, 1 d and 28 d. Dissolved organic carbon (DOC) patterns highlighted that: there was a 'soil effect' which increased organic matter (OM) degradation in all conditions compared to vinasse incubated alone; and OM degradation was faster under aerobic conditions since 500 mg kg{sup -1} of C remained after aerobic incubation, as compared to 4000 mg kg{sup -1} at the end of the anaerobic incubation period. No changes were detected by Fourier transform infrared spectroscopy (FTIR) between 2 h and 1 d incubation. At 28 days incubation, the FTIR signal of the aerobic samples was deeply modified, thus confirming the high OM degradation. Under anaerobic conditions, the main polysaccharide contributions ({nu}(C-O)) disappeared at 1000 and 1200 cm{sup -1}, as also confirmed by the {sup 13}C NMR findings. Under aerobic incubation, a 50% decrease in the polysaccharide proportion was observed. Under anaerobic conditions, significant chemical modifications of the organic fraction were detected, namely formation of low molecular weight organic acids.

  14. Spectroscopic characterization of organic matter of a soil and vinasse mixture during aerobic or anaerobic incubation.

    PubMed

    Doelsch, Emmanuel; Masion, Armand; Cazevieille, Patrick; Condom, Nicolas

    2009-06-01

    Mineralization potentials are often used to classify organic wastes. These methods involve measuring CO(2) production during batch experiments, so variations in chemical compounds are not addressed. Moreover, the physicochemical conditions are not monitored during the reactions. The present study was designed to address these deficiencies. Incubations of a mixture of soil and waste (vinasse at 20% dry matter from a fermentation industry) were conducted in aerobic and anaerobic conditions, and liquid samples obtained by centrifugation were collected at 2h, 1d and 28 d. Dissolved organic carbon (DOC) patterns highlighted that: there was a "soil effect" which increased organic matter (OM) degradation in all conditions compared to vinasse incubated alone; and OM degradation was faster under aerobic conditions since 500 mgkg(-1) of C remained after aerobic incubation, as compared to 4000 mgkg(-1) at the end of the anaerobic incubation period. No changes were detected by Fourier transform infrared spectroscopy (FTIR) between 2h and 1d incubation. At 28 days incubation, the FTIR signal of the aerobic samples was deeply modified, thus confirming the high OM degradation. Under anaerobic conditions, the main polysaccharide contributions (nu(C-O)) disappeared at 1000 and 1200 cm(-1), as also confirmed by the (13)C NMR findings. Under aerobic incubation, a 50% decrease in the polysaccharide proportion was observed. Under anaerobic conditions, significant chemical modifications of the organic fraction were detected, namely formation of low molecular weight organic acids. PMID:19157830

  15. Solvation of Nucleosides in Aqueous Mixtures of Organic Solvents: Relevance to DNA Open Basepairs

    PubMed Central

    Ababneh, Anas M.; Large, C. C.; Georghiou, S.

    2003-01-01

    Toward the goal of understanding how open basepairs in DNA interact with their heterogeneous environment, we have studied the steady-state intrinsic fluorescence properties of the purine and pyrimidine deoxynucleosides in organic solvents in the presence of small amounts of water. The organic solvents used in the present study were: n-butanol, acetonitrile, methanol, n-propanol, isopropanol, and isobutanol. For n-butanol and acetonitrile, which have a high degree of amphiphilicity and weak hydrogen bonding ability, respectively, the fluorescence spectral properties of the purines are found to depend on the sequence of steps in which the aqueous mixtures were formed. By contrast, no such dependence was observed in the mixtures with any of the other solvents used in the present study. Moreover, no such dependence was observed for the pyrimidines. These findings suggest that the final solvation network around the purines is dependent on the nature of the environment to which they were initially exposed. This would tend to present an impediment to the closing of AT or GC basepairs in DNA that become open as a result of structural fluctuations, DNA bending, or protein-DNA interactions. PMID:12885656

  16. Evaluation of the nephrotoxicity of complex mixtures containing organics and metals: advantages and disadvantages of the use of real-world complex mixtures.

    PubMed

    Simmons, J E; Yang, R S; Berman, E

    1995-02-01

    As part of a multidisciplinary health effects study, the nephrotoxicity of complex industrial waste mixtures was assessed. Adult, male Fischer 344 rats were gavaged with samples of complex industrial waste and nephrotoxicity evaluated 24 hr later. Of the 10 tested samples, 4 produced increased absolute or relative kidney weight, or both, coupled with a statistically significant alteration in at least one of the measured serum parameters (urea nitrogen (BUN), creatinine (CREAT), and BUN/CREAT ratio). Although the waste samples had been analyzed for a number of organic chemicals and 7 of the 10 samples were analyzed also for 12 elemental metals and metalloids, their nephrotoxicity was not readily predicted from the partial chemical characterization data. Because the chemical form or speciation of the metals was unknown, it was not possible to estimate their contribution to the observed biological response. Various experimental approaches, including use of real-world complex mixtures, chemically defined synthetic mixtures, and simple mixtures, will be necessary to adequately determine the potential human health risk from exposure to complex chemical mixtures. PMID:7621803

  17. Decrease in the abundance and viability of oceanic phytoplankton due to trace levels of complex mixtures of organic pollutants.

    PubMed

    Echeveste, Pedro; Dachs, Jordi; Berrojalbiz, Naiara; Agustí, Susana

    2010-09-01

    Long range atmospheric transport and deposition is a significant introduction pathway of organic pollutants to remote oceanic regions, leading to their subsequent accumulation in marine organisms. Persistent organic pollutants (POPs) bioconcentrate in planktonic food webs and these exert a biogeochemical control on the regional and global cycling of POPs. Therefore, an important issue is to determine whether the anthropogenic chemical perturbation of the biosphere introduced by the myriad of organic pollutants present in seawater influences phytoplankton abundance and productivity. The results reported here from five sets of experiments performed in the NE Atlantic Ocean show that there is a toxic effect induced by trace levels of complex mixtures of organic pollutants on phytoplankton oceanic communities. The levels of single pollutant, such as phenanthrene and pyrene, at which lethality of phytoplankton is observed are high in comparison to field levels. Complex mixtures of organic pollutants, however, have an important toxic effect on phytoplankton abundances, viability and concentrations of Chlorophyll a at pollutant concentrations 20-40 folds those found in the open ocean. The toxicity of these complex mixtures of organic pollutants exceeds by 10(3) times the toxicity expected for a single pollutant. Therefore, our results point out the need for a systematic investigation of the influence of complex mixtures of organic hydrophobic pollutants to oceanic phytoplankton communities, a perturbation not accounted for on previous assessments of anthropogenic pressures in the marine environment. PMID:20673958

  18. A mixture of environmental organic contaminants in lake sediments affects hatching from Daphnia resting eggs.

    PubMed

    Möst, Markus; Chiaia-Hernandez, Aurea C; Frey, Martin P; Hollender, Juliane; Spaak, Piet

    2015-02-01

    Despite the relevance of resting eggs for ecology and evolution of many aquatic organisms and their exposure to contaminants accumulating in sediments, ecotoxicological studies using resting eggs are vastly underrepresented. The authors established a method to perform exposure assays with resting eggs produced by the Daphnia longispina species complex, key species in large lake ecosystems. A mixture of organic contaminants previously detected in sediments of Lake Greifensee was selected to test the potential effect of organic contaminants present in sediments on the hatching process. Resting eggs were exposed to a mix of 10 chemicals, which included corrosion inhibitors, biocides, pesticides, and personal care products, for a period of 15?d. Using an automated counting software, the authors found a significant increase in hatching success in the exposed resting eggs compared with controls. Such an effect has not yet been reported from ecotoxicological assays with resting eggs. Possible mechanistic explanations as well as the potential implications on the ecology and evolution of aquatic species that rely on a resting egg banks are discussed. Observed increased mortality and developmental abnormalities for hatchlings in the exposure treatments can be explained by toxic contaminant concentrations. The results of the present study highlight the need for additional studies assessing the effects of organic contaminants on resting egg banks and aquatic ecosystems. PMID:25394187

  19. Can highly hydrophobic organic substances cause aquatic baseline toxicity and can they contribute to mixture toxicity?

    PubMed

    Mayer, Philipp; Reichenberg, Fredrik

    2006-10-01

    Effect concentrations for aquatic baseline toxicity generally decrease with increasing log octanol-water partition co-efficient (Kow) values of up to 5 to 6, whereas less is known about the baseline toxicity of organic chemicals with log Kow values above 6. A physicochemical analysis of the dissolution process for organic chemicals was combined with reported baseline toxicity data, leading to the following conclusions. First, no absolute hydrophobicity cutoff exists for baseline toxicity at a log Kow value of 6, because aquatic baseline toxicity for fish and algae was observed for chemicals with log Kow values greater than 6.5 and with effect concentrations less than 10 microg/L. Second, the baseline toxicity of hydrophobic organic substances was exerted at a relatively constant chemical activity of 0.01 to 0.1. Finally, organic chemicals with high melting points cannot provide sufficient chemical activity to exert baseline toxicity when considered as individual, pure chemicals. However, such substances are still expected to contribute to baseline toxicity when part of a complex mixture. PMID:17022404

  20. Adsorbate shape selectivity: Separation of the HF\\/134a azeotrope over carbogenic molecular sieve

    Microsoft Academic Search

    Allan Hong; Ravindra K. Mariwala; Michael S. Kane; Henry C. Foley

    1995-01-01

    Experimental evidence is provided for adsorptive shape selectivity in the separation of the azeotrope between HF and 1,1,1,2-tetrafluoroethane (134a) over pyrolyzed poly(furfuryl alcohol)-derived carbogenic molecular sieve (PPFA-CMS). The separation can be accomplished over coconut charcoal or Carbosieve G on the basis of the differences in the extent of equilibrium adsorption of HF and 134a. On these adsorbents 134a is more

  1. Improved electrolytes for Li-ion batteries: Mixtures of ionic liquid and organic electrolyte with enhanced safety and electrochemical performance

    Microsoft Academic Search

    A. Guerfi; M. Dontigny; P. Charest; M. Petitclerc; M. Lagacé; A. Vijh; K. Zaghib

    2010-01-01

    Physical and electrochemical characteristics of Li-ion battery systems based on LiFePO4 cathodes and graphite anodes with mixture electrolytes were investigated. The mixed electrolytes are based on an ionic liquid (IL), and organic solvents used in commercial batteries. We investigated a range of compositions to determine an optimum conductivity and non-flammability of the mixed electrolyte. This led us to examine mixtures

  2. Complex Singular Points of the Tie-Line Vector Field Diagrams of Ternary Mixtures

    Microsoft Academic Search

    L. A. Serafimov; T. V. Chelyuskina

    2005-01-01

    Complex singular points of the tie-line vector field diagrams of liquid-vapor ternary systems are considered in terms of the theory of stationary vector fields and bifurcation theory. These complex singular points are found to be tangential azeotropic points of different orders, which play a decisive role in transformations of the diagrams of heterogeneous mixtures.

  3. Neurobehavioral and sensory irritant effects of controlled exposure to a complex mixture of volatile organic compounds

    SciTech Connect

    Otto, D.; Molhave, L.; Rose, G.; Hudnell, H.K.; House, D. (Environmental Protection Agency, Research Triangle Park, NC (USA))

    1990-11-01

    Subjective reactions of discomfort, impaired air quality, irritation of mucosal membranes, and impaired memory have been reported in chemically sensitive subjects during exposure to volatile organic compounds (VOCs) found in new buildings. Sixty-six normal healthy male subjects aged 18-39 were exposed for 2.75 hr to a complex VOC mixture at 0 and 25 mg/m3. Each subject completed control and exposure sessions at one-week intervals in counterbalanced order. Measurements included comfort ratings of eye, nose and throat irritation, symptom questionnaire and computerized behavioral tests. Subjects found the odor of VOCs unpleasantly strong and reported that VOC exposure degraded air quality, increased headache and produced general discomfort. VOC exposure did not affect performance on any behavioral tests.

  4. Neurotoxic effects of controlled exposure to a complex mixture of volatile organic compounds. Final report

    SciTech Connect

    Otto, D.A.; Molhave, L.; Hudnell, H.K.; Goldstein, G.; O'Neil, J.

    1990-03-01

    Subjective reactions of discomfort, impaired air quality, irritation of mucosal membranes, and impaired memory have been reported in chemically sensitive subjects during exposure to volatile organic compounds (VOCs) found in new buildings. 66 normal healthy male subjects aged 18-39 were exposed for 2.75 hrs to a complex VOC mixture at O and 25 mg/cu m. Each subject completed control and exposure sessions at one week intervals in counterbalanced order. Measurements included comfort ratings of eye, nose and throat irritation, symptom questionnaire and computerized behavioral tests. Subjects found the odor of VOCs unpleasant and strong and reported that VOC exposure degraded air quality, increased headache and produced general discomfort. VOC exposure did not affect performance on any behavioral tests. Results indicate that subjective reactions to VOCs are not limited to chemically sensitive individuals since the study population is a subgroup that is probably least likely to be affected by chemical exposure.

  5. Laser fluorimetry of mixtures of polyatomic organic compounds using artificial neural networks

    SciTech Connect

    Dolenko, S A [D.V. Skobel'tsyn Institute of Nuclear Physics, M.V. Lomonosov Moscow State University, Moscow (Russian Federation); Gerdova, I V; Dolenko, T A; Fadeev, V V [Department of Physics, M.V. Lomonosov Moscow State University, Moscow (Russian Federation)

    2001-09-30

    New possibilities of laser fluorimetry offered by the use of algorithms for solving inverse problems based on artificial neural networks are demonstrated. A two-component mixture of polyatomic organic compounds is analysed by three methods of laser fluorimetry: a direct analysis of the fluorescence band, the kinetic fluorimetry (when durations of the laser pulse and the detector gate pulse are comparable with the fluorescence lifetimes or exceed them), and the saturation fluorimetry. The numerical experiments showed that the use of artificial neural networks in these methods provides a high practical stability of the solution of inverse problems and ensures a high sensitivity and a high accuracy of determining the contribution of components to fluorescence and of measuring molecular photophysical parameters, which can be used for the identification of components. (laser applications and other topics in quantum electronics)

  6. Technical Note: Dissolved organic matter fluorescence - a finite mixture approach to deconvolve excitation-emission matrices

    NASA Astrophysics Data System (ADS)

    Butturini, A.; Ejarque, E.

    2013-03-01

    The analysis of the shape of excitation-emission matrices (EEMs) is a relevant tool for exploring the origin, transport and fate of dissolved organic matter (DOM) in aquatic ecosystems. Within this context, the decomposition of EEMs is acquiring a notable relevance. A simple mathematical algorithm that automatically deconvolves single EEM is described, creating new possibilities for the comparison of DOM fluorescence properties and EEMs that are very different from each other. A mixture model approach is adopted to decompose complex surfaces into sub-peaks. The laplacian operator and the Nelder-Mead optimization algorithm are implemented to individuate and automatically locate potential peaks in the EEM landscape. A small heterogeneous data set of 21 EEMs from a human-impacted Mediterranean river is used to describe the model application and to illustrate a strategy that optimises the search for the optimal output.

  7. Polychlorinated biphenyl concentration changes in sewage sludge and organic municipal waste mixtures during composting and anaerobic digestion.

    PubMed

    Siebielska, Izabela; Side?ko, Robert

    2015-05-01

    We determined the changes in polychlorinated biphenyl (PCB) concentrations in a mixture of sewage sludge and the organic fraction of municipal waste during composting and during anaerobic digestion. The processes were carried out on a laboratory scale. The PCBs were analyzed in the waste samples using gas chromatography-mass spectrometry. We evaluated the rates at which the PCB concentrations decreased during composting and during anaerobic digestion and compared the PCB degradation kinetics during these processes. The most important conclusion of this work is that anaerobic digestion is much more effective than composting at removing PCBs from a mixture of sewage sludge and the organic fraction of municipal waste. PMID:25618191

  8. The shock synthesis of complex organics from impacts into cometary analogue mixtures

    NASA Astrophysics Data System (ADS)

    Price, M.; Wozniakiewicz, P.; Cole, M.; Martins, Z.; Burchell, M.

    2014-07-01

    Introduction: If amino acids are required for the evolution of life, what was their source? Many different theories abound as to the source of amino acids on the early Earth including exogenous delivery from comets/asteroids (for example, glycine was found recently on comet Wild-2 [1]), formation in the protoplanetary nebula [2], or UV catalysed reactions of gases [3]. An alternative explanation is that amino acids can be shock-synthesised during the impact on an icy body onto a rocky body (or, equivalently, the impact of rocky body onto an icy surface). This theory is supported by computer simulations [4] and by very recent experimental data, which demonstrated the formation of simple (including abiotic) amino acids from shocks into ice mixtures mimicking the composition of comets and the surfaces of the icy Jovian and Saturnian satellites. Although the results from these experiments are fundamentally important, the yield of synthesised amino acids was low (nano-grams of material), complicating their detection and identification. In order to increase the collected yield of complex organics, and aid in their detection and identification, we have implemented a new collection technique within our hypervelocity impact facility. Experimental Methodology: Figure 1A) shows a low-resolution high-speed photograph of an impact plasma generated from an impact of a stainless-steel sphere into a mixture of water, CO_{2}, ammonia, and methanol ices. The plasma has an intense blue colour, and lasted for < 1 msec (the frame-rate of the camera). It is during and within this flash that complex organics are most likely synthesised, and thus to maximise the collection of these materials, we have implemented a new collection mechanism. Figure 1B) shows the prototype collection mechanism. Here an aluminium cold-plate (˜150 K) is placed in front of the target holder containing the ice mixtures. The plate has a central hole which allows the projectile to pass through to impact the ice mix. The plate also has two brass holders (Fig. 1C) which contain 10-mm diameter discs of high purity, sterilised gold foil (also at low temperature). During the impact, the plasma will condense onto the cold surfaces of the gold foil. One of the gold foils is pointed directly at the ice mixture, the other is pointed backwards into the gun's target chamber (and thus acts as a control). The gold discs can then be removed (Fig. 1D) and mounted onto stubs for analyses using Raman spectroscopy, SEM-EDX, GC-MS as required. Preliminary Results: Several trial shots have been performed using this system and residues have been found. The initial analysis of these residues is now underway and the results will be presented at the conference. If successful, this collection and analysis methodology will greatly speed up the number of experiments that can be done, allowing us to explore a large parameter space and determine the efficiency of shock syntheses of complex organics as a function of impact speed (peak shock pressure) and target composition.

  9. Transcriptional Regulation in Liver and Testis Associated with Developmental and Reproductive Effects in Male Zebrafish Exposed to Natural Mixtures of Persistent Organic Pollutants (POP)

    Microsoft Academic Search

    Rasoul Nourizadeh-Lillabadi; Jan L. Lyche; Camilla Almaas; Benedicte Stavik; S. Jannicke Moe; Mona Aleksandersen; Vidar Berg; Kjetill S. Jakobsen; Nils Chr. Stenseth; Janneche Utne Skåre; Peter Alestrøm; Erik Ropstad

    2009-01-01

    Persistent organic pollutants (POP) occur as mixtures in nature and it is difficult to predict the toxicity of such mixtures based on knowledge about toxicity and mechanisms of action for single compounds. The present knowledge on the combined toxic effects and modes of actions of exposure to mixtures is limited. Thus, the scientifically based hazard and risk assessment of POP

  10. A COMPARISON OF THE LETHAL AND SUBLETHAL TOXICITY OF ORGANIC CHEMICAL MIXTURES TO THE FATHEAD MINNOW (PIMEPHALES PROMELAS)

    EPA Science Inventory

    The joint toxic effects of known binary and multiple organic chemical mixtures to the fathead minnow (Pimephales promelas) were defined at both the 96-h 50% lethal effect concentration (LC50) and sublethal (32-d growth) response levels for toxicants with a narcosis I, narcosis II...

  11. Neither azeotropic drying, nor base nor other additives: a minimalist approach to (18)F-labeling.

    PubMed

    Richarz, R; Krapf, P; Zarrad, F; Urusova, E A; Neumaier, B; Zlatopolskiy, B D

    2014-10-28

    A novel, efficient, time-saving and reliable radiolabeling procedure via nucleophilic substitution with [(18)F]fluoride is described. Different radiolabeled aliphatic and aromatic compounds were prepared in high radiochemical yields simply by heating of quaternary anilinium, diaryliodonium and triarylsulfonium [(18)F]fluorides in suitable solvents. The latter were obtained via direct elution of (18)F(-) from an anion exchange resin with alcoholic solutions of onium precursors. Neither azeotropic evaporation of water, nor a base, nor any other additives like cryptands or crown ethers were necessary. Due to its simplicity this method should be highly suitable for automated radiosyntheses, especially in microfluidic devices. PMID:25190038

  12. Modeling competitive adsorption of mixtures of volatile organic compounds in a fixed-bed of beaded activated carbon.

    PubMed

    Tefera, Dereje Tamiru; Hashisho, Zaher; Philips, John H; Anderson, James E; Nichols, Mark

    2014-05-01

    A two-dimensional mathematical model was developed to study competitive adsorption of n-component mixtures in a fixed-bed adsorber. The model consists of an isotherm equation to predict adsorption equilibria of n-component volatile organic compounds (VOCs) mixture from single component isotherm data, and a dynamic adsorption model, the macroscopic mass, energy and momentum conservation equations, to simulate the competitive adsorption of the n-components onto a fixed-bed of adsorbent. The model was validated with experimentally measured data of competitive adsorption of binary and eight-component VOCs mixtures onto beaded activated carbon (BAC). The mean relative absolute error (MRAE) was used to compare the modeled and measured breakthrough profiles as well as the amounts of adsorbates adsorbed. For the binary and eight-component mixtures, the MRAE of the breakthrough profiles was 13 and 12%, respectively, whereas, the MRAE of the adsorbed amounts was 1 and 2%, respectively. These data show that the model provides accurate prediction of competitive adsorption of multicomponent VOCs mixtures and the competitive adsorption isotherm equation is able to accurately predict equilibrium adsorption of VOCs mixtures. PMID:24670053

  13. Thermodynamics of Mixtures Containing Organic Carbonates. Part XV. Application of the Kirkwood-Buff Theory to the Study of Interactions in Liquid Mixtures Containing Dialkyl Carbonates and Alkanes, Benzene, CCl 4 or 1-Alkanols

    Microsoft Academic Search

    Juan Antonio González; Ismael Mozo; S. Villa; Nicolás Riesco; Isaías García de la Fuente; José Carlos Cobos

    2006-01-01

    Binary liquid mixtures containing a dialkyl carbonate (dimethyl or diethyl carbonate) and organic solvents such as alkanes, benzene, CCl4, or 1-alkanols were studied within the framework of the Kirkwood-Buff formalism. The Kirkwood-Buff integrals, linear coefficients of preferential solvation and local mole fractions were calculated. Results were interpreted assuming that the mixtures with alkanes or 1-alkanols are not random mixtures, which

  14. Secondary organic aerosol formation from photooxidation of a mixture of dimethyl sulfide and isoprene

    NASA Astrophysics Data System (ADS)

    Chen, Tianyi; Jang, Myoseon

    2012-01-01

    Secondary organic aerosol (SOA) created from the photooxidation of a mixture of isoprene and dimethyl sulfide (DMS) was studied at different NO x concentrations (40-220 ppb) and humidities (12%, 42% and 80%) using a Teflon film indoor chamber. To study the effect of isoprene on DMS products, the major DMS photooxidation products, such as sulfuric acid, methanesulfonic acid (MSA) and methanesulfinic acid (MSIA), were quantified in both the presence and the absence of isoprene using a Particle-Into-Liquid-Sampler coupled with Ion Chromatography (PILS-IC). The resulting PILS-IC data showed that the DMS aerosol yield significantly decreased due to the photooxidation of isoprene. A 35.2% DMS aerosol yield reduction was observed due to 800 ppb isoprene in 185 ppb NO x and 140 ppb DMS. Among the aerosol-phase DMS oxidation products, MSA was the most sensitive to the presence of isoprene (e.g., 46% reduction). The DMS aerosol product analysis indicates that isoprene oxidation affects the pathways of MSA formation on the aerosol surface. Using a new approach that implements an Organic Carbon (OC) analyzer, the isoprene SOA yield ( Yiso) in the DMS/isoprene/NO x system was also estimated. The OC data showed that Yiso increased significantly with DMS compared to the Yiso without DMS. For example, Yiso with 80 ppb NO x and 840 ppb isoprene was increased by 124.6% due to 100 ppb DMS at RH = 42%. Our study suggests that the heterogeneous reactions of isoprene oxidation products with the highly acidic products (e.g., MSA and sulfuric acid) from DMS photooxidation can considerably contribute to the Yiso increase.

  15. Pervaporation separation of ethyl acetate–ethanol binary mixtures using polydimethylsiloxane membranes

    Microsoft Academic Search

    A. Hasano?lu; Y. Salt; S. Kele?er; S. Özkan; S. Dinçer

    2005-01-01

    Pervaporation separation of azeotrope forming ethyl acetate–ethanol mixtures was investigated by using a selfmade polydimethylsiloxane (PDMS) membrane. Sorption, desorption and pervaporation experiments for ethyl acetate–ethanol mixture with different concentrations were conducted at 30, 40 and 50°C. The effect of process parameters such as feed concentration and temperature on flux and selectivity is discussed. Equilibrium curves are determined by vapor–liquid equilibrium

  16. Evidences of nonideal mixing in poly(ethylene glycol)/organic solvent mixtures by Brillouin scattering.

    PubMed

    Pochylski, M; Aliotta, F; B?aszczak, Z; Gapi?ski, J

    2006-01-12

    The concentration dependence of the hypersonic properties of solutions of poly(ethylene glycol) of mean molecular mass 600 g/mol (PEG600) in benzene and toluene has been investigated by Brillouin scattering. The two solvents are very similar in structure and chemical properties, but while benzene is nonpolar, toluene possess a modest dipole. In both solvents a high-frequency relaxation process has been observed at high concentrations which has been assigned to conformational rearrangements of the polymeric chains, triggered by reorientation of the side groups. In both cases, the concentration dependence of the adiabatic compressibility deviates significantly from linearity, indicating the existence of nonideal mixing phenomena driven by aggregation processes taking place in the systems. However, there is no temperature dependence for solutions of PEG600 in benzene; on the contrary, the results obtained for solutions of PEG600 in toluene are noticeably dependent on the temperature. The comparison of the experimental data with the results of previous experiments on similar systems allows a general picture for weakly interacting mixtures of hydrogen-bonded systems and organic solvents to be developed. In particular, in the presence of a nonpolar solvent molecule the local structure of the mixture is dominated by solute self-association processes and any resulting solute-solvent correlation is barely induced by excluded volume effects. At high enough dilution the self-aggregation of solute molecules produces a variety of new local topologies that cannot be observed in bulk solute, and as a consequence, the concentration evolution of the system is too rich to be described in terms of a linear combination of a few components over the whole concentration range. The situation seems to be simpler for the polar toluene solvent molecules, where a three-component model seems able to fit the experimental concentration dependence of the hypersonic velocity. This result is interpreted to imply that the interaction between the solvent dipoles and the active sites of the solute produces a relatively stable heterocoordination, while the relevance of self-association is partially reduced. PMID:16471559

  17. RESPONSE OF PORTABLE VOC (VOLATILE ORGANIC COMPOUNDS) ANALYZERS TO CHEMICAL MIXTURES

    EPA Science Inventory

    The report gives the responses of two types of portable VOC analyzers (Century Systems OVA-108 and Bacharach TLV Sniffer), calibrated with methane and used to measure a variety of chemical vapor mixtures. Instrument response data for both binary and ternary mixtures of selected c...

  18. Assessment of oxidative DNA damage formation by organic complex mixtures from airborne particles PM(10).

    PubMed

    Gábelová, Alena; Valovicová, Zuzana; Lábaj, Juraj; Bacová, Gabriela; Binková, Blanka; Farmer, Peter B

    2007-07-01

    The free radical generating activity of airborne particulate matter (PM(10)) has been proposed as a primary mechanism in biological activity of ambient air pollution. In an effort to determine the impact of the complex mixtures of extractable organic matter (EOM) from airborne particles on oxidative damage to DNA, the level of 8-oxo-2'-deoxyguanosine (8-oxodG), the most prevalent and stable oxidative lesion, was measured in the human metabolically competent cell line Hep G2. Cultured cells were exposed to equivalent EOM concentrations (5-150microg/ml) and oxidative DNA damage was analyzed using a modified single cell gel electrophoresis (SCGE), which involves the incubation of whole cell DNA with repair specific DNA endonuclease, which cleaves oxidized DNA at the sites of 8-oxodG. EOMs were extracted from PM(10) collected daily (24h intervals) in three European cities: Prague (Czech Republic, two monitoring sites, Libus and Smíchov), Kosice (Slovak Republic) and Sofia (Bulgaria) during 3-month sampling periods in the winter and summer seasons. No substantial time- and dose-dependent increase of oxidative DNA lesions was detected in EOM-treated cells with the exception of the EOM collected at the monitoring site Kosice, summer sampling. In this case, 2h cell exposure to EOM resulted in a slight but significant increase of oxidative DNA damage at three from total of six concentrations. The mean 8-oxodG values at these concentrations ranged from 15.3 to 26.1 per 10(6) nucleotides with a value 3.5 per 10(6) nucleotides in untreated cells. B[a]P, the positive control, induced a variable but insignificant increase of oxidative DNA damage in Hep G2 cell (approximately 1.6-fold increase over control value). Based on these data we believe that EOM samples extracted from airborne particle PM(10) play probably only a marginal role in oxidative stress generation and oxidative lesion formation to DNA. However, adsorbed organic compounds can undergo various interactions (additive or synergistic) with other PM components or physical factors (UV-A radiation) and in this way they might enhance/multiply the adverse health effects of air pollution. PMID:17403525

  19. Survey of Binary Azeotropes as Physical Chemistry Lab Experiments with Attention to Cost, Safety, and the Environment

    Microsoft Academic Search

    Robert J. Glinski; Christopher W. Smith; Jason B. Cooke

    1999-01-01

    A survey is presented of possible binary azeotropic systems suitable for study in an undergraduate physical chemistry laboratory. From a range of sources, a list has been compiled of the most acceptable systems on the basis of health, safety, waste disposal, and practicability concerns. More than 80 systems were reviewed. For comparison purposes, the list was reduced to a table

  20. Nitrate Anion Recognition in Organic-Aqueous Solvent Mixtures by a Bis(triazolium)acridine-Containing [2]Rotaxane.

    PubMed

    Martí-Centelles, Vicente; Beer, Paul D

    2015-06-22

    The synthesis of a novel [2]rotaxane host system containing a bis(triazolium)acridine-based axle component is reported. (1) H?NMR anion-binding titrations reveal that the rotaxane is able to recognise selectively the NO3 (-) anion over a range of more basic oxoanions (AcO(-) , HCO3 (-) and H2 PO4 (-) ) in a competitive organic-aqueous solvent mixture. PMID:25925564

  1. Vapor–liquid equilibria of novel chemicals and their mixtures as R-22 alternatives

    Microsoft Academic Search

    Ismail Kul; Darryl D DesMarteau; Adolph L Beyerlein

    2000-01-01

    Vapor–liquid equilibrium (VLE) vapor pressures are reported for binary mixtures; octafluoromethylethylether+1,1-difluoroethane (RE218\\/R152a), trifluoromethylpentafluorosulfur(VI)+1,1-difluoroethane (CF3SF5\\/R152a), hexafluorodimethylthioether+1,1,1,2-tetrafluoroethane (CF3SCF3\\/R134a), and pentafluorodimethylether+1,1,1-trifluorodimethylether (RE125\\/RE143a). The mixtures; (RE218\\/R152a), (CF3SF5\\/R152a), and (CF3SCF3\\/R134a) form minimum boiling azeotropes with the normal boiling points; 237.9K (?35.3°C), 239.7K (?33.5°C), and 243.0K (?30.2°C), respectively, and gas–liquid critical temperatures of 353.3K (80.1°C), 365.7K (92.5°C) and 368.2K (95.0°C), respectively. The azeotropic mixtures have sufficiently

  2. Global phase behavior of supercritical water – environmentally significant organic chemicals mixtures

    Microsoft Academic Search

    SERGEY V. ARTEMENKO; VICTOR A. MAZUR

    \\u000a Recent developments of the global phase equilibria studies of binary mixtures provide some basic ideas of how the required\\u000a methods can be developed based on global phase diagrams for visualization of the phase behavior of mixtures. The mapping of\\u000a the global equilibrium surface in the parameter space of the equation of state (EoS) model provides the most comprehensive\\u000a system of

  3. Catalytic oxidation of volatile organic compounds (VOCs) mixture (isopropanol\\/ o-xylene) on zeolite catalysts

    Microsoft Academic Search

    R. Beauchet; P. Magnoux; J. Mijoin

    2007-01-01

    The catalytic oxidation of isopropanol and o-xylene alone and in mixture was investigated over basic zeolites (CsX and NaX) and an acidic zeolite (HY). For a given temperature, the conversion of VOCs mixture into CO2 increases with the basicity of the zeolite. Results show that VOCs are oxidized through a basic mechanism over NaX, and through an acidic mechanism over

  4. Journal of the Korean Physical Society, Vol. 42, No. 1, January 2003, pp. 162166 Self-Organized Patterns in Mixtures of Microtubules and Motor Proteins

    E-print Network

    Kahng, Byungnam

    -Organized Patterns in Mixtures of Microtubules and Motor Proteins Jeenu Kim School of Physics and Center occurring in mixtures of microtubules and molec- ular motors and their density profiles. By separately in the motion of bound motors, we develop a continuum equation for the dynamics of motor and microtubule

  5. In vitro steroidogenic effects of mixtures of persistent organic pollutants (POPs) extracted from burbot ( Lota lota) caught in two Norwegian lakes

    Microsoft Academic Search

    Karin E. Zimmer; Mauricio Montaño; Ingrid Olsaker; Ellen Dahl; Vidar Berg; Camilla Karlsson; Albertinka J. Murk; Janneche U. Skaare; Erik Ropstad; Steven Verhaegen

    2011-01-01

    This study investigated the effects of two mixtures of persistent organic pollutants (POPs) on steroidogenesis in the H295R cell line. The two mixtures were obtained from the livers of burbot (Lota lota) caught in two Norwegian lakes (Mjøsa and Losna) with different contaminant profiles. Steroid hormone levels in the cell culture medium and mRNA levels of 16 genes involved in

  6. Microporous metal-organic framework with dual functionalities for highly efficient removal of acetylene from ethylene/acetylene mixtures.

    PubMed

    Hu, Tong-Liang; Wang, Hailong; Li, Bin; Krishna, Rajamani; Wu, Hui; Zhou, Wei; Zhao, Yunfeng; Han, Yu; Wang, Xue; Zhu, Weidong; Yao, Zizhu; Xiang, Shengchang; Chen, Banglin

    2015-01-01

    The removal of acetylene from ethylene/acetylene mixtures containing 1% acetylene is a technologically very important, but highly challenging task. Current removal approaches include the partial hydrogenation over a noble metal catalyst and the solvent extraction of cracked olefins, both of which are cost and energy consumptive. Here we report a microporous metal-organic framework in which the suitable pore/cage spaces preferentially take up much more acetylene than ethylene while the functional amine groups on the pore/cage surfaces further enforce their interactions with acetylene molecules, leading to its superior performance for this separation. The single X-ray diffraction studies, temperature dependent gas sorption isotherms, simulated and experimental column breakthrough curves and molecular simulation studies collaboratively support the claim, underlying the potential of this material for the industrial usage of the removal of acetylene from ethylene/acetylene mixtures containing 1% acetylene at room temperature through the cost- and energy-efficient adsorption separation process. PMID:26041691

  7. Microporous metal–organic framework with dual functionalities for highly efficient removal of acetylene from ethylene/acetylene mixtures

    PubMed Central

    Hu, Tong-Liang; Wang, Hailong; Li, Bin; Krishna, Rajamani; Wu, Hui; Zhou, Wei; Zhao, Yunfeng; Han, Yu; Wang, Xue; Zhu, Weidong; Yao, Zizhu; Xiang, Shengchang; Chen, Banglin

    2015-01-01

    The removal of acetylene from ethylene/acetylene mixtures containing 1% acetylene is a technologically very important, but highly challenging task. Current removal approaches include the partial hydrogenation over a noble metal catalyst and the solvent extraction of cracked olefins, both of which are cost and energy consumptive. Here we report a microporous metal–organic framework in which the suitable pore/cage spaces preferentially take up much more acetylene than ethylene while the functional amine groups on the pore/cage surfaces further enforce their interactions with acetylene molecules, leading to its superior performance for this separation. The single X-ray diffraction studies, temperature dependent gas sorption isotherms, simulated and experimental column breakthrough curves and molecular simulation studies collaboratively support the claim, underlying the potential of this material for the industrial usage of the removal of acetylene from ethylene/acetylene mixtures containing 1% acetylene at room temperature through the cost- and energy-efficient adsorption separation process. PMID:26041691

  8. Pervaporation Separation of Water-Ethanol Mixtures Using Organic-Inorganic Nanocomposite Membranes

    EPA Science Inventory

    Preyssler type heteropolyacid viz., H14[NaP5W30O110] incorporated chitosan nanocomposite membranes (NCMs) were prepared by solution casting, characterized using a variety of techniques and employed in the pervaporation separation of water-ethanol mixtures as a function of feed wa...

  9. In vitro steroidogenic effects of mixtures of persistent organic pollutants (POPs) extracted from burbot (Lota lota) caught in two Norwegian lakes.

    PubMed

    Zimmer, Karin E; Montaño, Mauricio; Olsaker, Ingrid; Dahl, Ellen; Berg, Vidar; Karlsson, Camilla; Murk, Albertinka J; Skaare, Janneche U; Ropstad, Erik; Verhaegen, Steven

    2011-05-01

    This study investigated the effects of two mixtures of persistent organic pollutants (POPs) on steroidogenesis in the H295R cell line. The two mixtures were obtained from the livers of burbot (Lota lota) caught in two Norwegian lakes (Mjøsa and Losna) with different contaminant profiles. Steroid hormone levels in the cell culture medium and mRNA levels of 16 genes involved in steroidogenesis were investigated. The crude Lake Mjøsa extract had to be diluted ten times more than the Lake Losna extract in order to prevent cytotoxicity. The ten times diluted Lake Mjøsa mixture had higher levels of DDT and derivates (?DDTs, 1.7 times) and brominated flame retardants (?BDEs and HBCD, 15-25 times) than the Lake Losna mixture, which, on the other hand, had higher concentrations of ?PCBs (1.5 times higher) and also of HCB, ?HCH isomers and ?chlordane isomers (5-20 times higher). In the cell culture media, only cortisol levels were increased at the highest exposure concentration to the Lake Mjøsa mixture, while both cortisol and estradiol levels were increased following exposure to the two highest Lake Losna mixture exposure concentrations. Testosterone levels decreased only at the highest exposure concentration of the Lake Losna mixture. Multivariate models suggested that ?PCBs, and to a lesser extent ?DDTs, were responsible for the cortisol responses, while estradiol and testosterone alterations were best explained by HCB and ?PCBs, respectively. Exposure to the mixtures generally increased mRNA levels, with smaller effects exerted by the Lake Mjøsa mixture than the Lake Losna mixture. It was concluded that both mixtures affected steroidogenesis in the H295R cells. Small differences in mixture composition, rather than the high content of brominated flame retardants in the Lake Mjøsa mixture, were suggested to be the most probable reason for the apparent differences in potencies of the two mixtures. PMID:21420147

  10. Menstrual disturbances and hormonal changes in women workers exposed to a mixture of organic solvents in a pharmaceutical company

    PubMed Central

    Hassani, Somayeh; Namvar, Mohamad; Ghoreishvandi, Maryam; Attarchi, Mirsaeed; Golabadi, Majid; Seyedmehdi, Seyed Mohammad; Khodarahmian, Mahshad

    2014-01-01

    Background: Chemicals are among risk factors that can affect women's reproductive system. This study is aimed to investigate the association of occupational exposure to a mixture of organic solvents with menstruation disturbances and hormonal changes among female workers. Methods: Female workers of a pharmaceutical company were divided into three groups of non-exposed, lowexposed and highly-exposed to a mixture of organic solvents (formaldehyde, phenol, N-hexane, and chloroform) based on workplace measurements. Menstrual disturbances (in terms of short cycles, long cycles, irregular cycles, and bleeding or spotting between periods) and mean of hormone levels (including follicle stimulating hormone, luteinizing hormone, thyroid stimulating hormone, prolactin, estrogen and progesterone levels) were compared between these three groups. For investigating associations, logistic regression was performed. Results: Our study showed that mean length of cycles, duration of bleeding, and amount of flow and also prevalence of long cycles, irregular cycles, and bleeding or spotting between periods were higher in exposed groups (p?0.05). Odds ratio for prevalence of menstrual disturbances in the low exposure group and high exposure group were 9.69 (p=0.001) and 3.40 (p=0.002) respectively compared to the reference group. Estrogen and progesterone levels were not affected (p> 0.05), but other hormones levels were significantly disturbed in the exposed groups compared with the non-exposed group (p=0.001). Conclusion: Occupational exposure to the mixture of organic solvents may be associated with the increase of menstrual disorders and hormonal changes in female workers. Based on our findings, periodic evaluation of reproductive system of female workers in pharmaceutical companies is recommended. PMID:25695014

  11. Hazardous and Corrosive Gas Production in the Radiolysis of Water/Organic Mixtures in Model TRU Waste

    SciTech Connect

    LaVerne, Jay A.

    2005-06-01

    Experiments in combination with diffusion-kinetic modeling incorporating track structure simulations are used to examine the radiation chemistry of aqueous systems containing chlorinated hydrocarbons. Irradiations with both Co-60 gamma rays and alpha particles are employed in order to simulate typical mixed radiation environments encountered in waste management. The goal is to determine fundamental mechanisms, kinetics, and yields for the formation of potentially explosive gases and corrosive agents, such as H2 and HCl, respectively, in the radiolysis of water-organic mixtures. The radiation chemical systems studied are found throughout the DOE portfolio and are important in radioactive waste remediation and management.

  12. High resolution mass spectroscopy for the characterization of complex, fossil organic mixtures

    SciTech Connect

    Winans, R.E.; Haas, G.W.; Kim, Y.L.; Hunt, J.E. [Argonne National Lab., IL (United States)

    1995-12-31

    The nature of molecules with heteroatom functionality in the Argonne Premium Coal Samples and petroleum samples is being explored using high resolution mass spectrometry (HRMS). Both desorption electron impact and desorption chemical ionization (DCI) are used to sample the mixtures. Structural information is obtained from tandem MS experiments using high resolution to select the ions to fragment. The first DCI HRMS spectra of complex mixtures will be shown. Quantitative aspects and the method for obtaining precise mass measurements in chemical ionization will be discussed. Molecular weight distribution determined by DCI are similar to those determined by laser desorption and field ionization mass spectrometry with very little ion intensity observed at greater than 1000 Daltons. Results will be correlated with other techniques such as NMR, XPS, and XANES.

  13. Composition dependent structural organization in trihexyl(tetradecyl)phosphonium chloride ionic liquid-methanol mixtures.

    PubMed

    Gupta, Aditya; Sharma, Shobha; Kashyap, Hemant K

    2015-04-01

    This article reports results from the molecular dynamics simulations on the structural arrangement of the ions and molecules in the mixtures of trihexyl(tetradecyl)phosphonium chloride ([P666,14 (+)][Cl(-)]) ionic liquid (IL) and methanol (MeOH) over the entire composition range. Effects of composition on the charge and polarity orderings have been investigated via computation of X-ray scattering structure function, S(q), and by using a partitioning scheme proposed for such multi-component mixtures. Except for the neat methanol liquid, the total S(q) shows two peaks in its intermolecular region for all the mole-fractions. The lowest q peak is dominated primarily by anion-anion, cation-anion, and methanol-anion correlations. Our results signify that the methanol bulk structure, which predominantly has short-distance characteristic correlations and is governed by polar group of methanol, is retained for xIL ? 0.1. Then, the mixture goes through gradual structural changes from methanol-like to the IL-like for 0.1 < xIL ? 0.7. The dipolar interaction between methanol molecules weakens in this range, and the structural landscape of the mixture is steered by strong ion-ion, anion-methanol, and nonpolar interactions. The IL-like structural arrangement is virtually recovered for xIL > 0.7. At all the compositions studied, while the cation head groups are predominantly solvated by anions and subsequently by methanol molecules, the polar hydroxyl group of methanol is preferentially solvated by the anions. The radial distribution functions of selected pair of atomic species have also confirmed these observations. PMID:25854249

  14. Preparation and Characterization of Inorganic Silica-Organic Polymer Mixture Based C 16 Capillary Monolithic Column

    Microsoft Academic Search

    Yuan-Chao WANG; Qiong WU; Ying-Zhi JIN; Jin-Hua LIU

    2010-01-01

    A novel inorganic silica-organic polymer mixed-based capillary electrochromatography monolithic column was prepared by using precursor 3-(trimethoxysilyl) propyl methacrylate with double-functional group hydrolysis\\/polycondensation in acidic aqueous solution, followed by double-bond co-polymerization with organic monomer hexadecyl mathacrylate under the thermal initiated condition, and the combination of preparation of silica-based monolithic column and organic polymer monolithic column was suggested. A simple operation of

  15. Greenhouse gas production in mixtures of soil with composted and noncomposted biochars is governed by char-associated organic compounds.

    PubMed

    Borchard, Nils; Spokas, Kurt; Prost, Katharina; Siemens, Jan

    2014-05-01

    Biochar application to soil has the potential to increase soil productivity while reducing anthropogenic greenhouse gas (GHG) emissions to the atmosphere. However, techniques for conditioning this material for maximizing its effects as a soil amendment require elucidation. We examined changes of organic matter associated with two biochars after 175 d of composting and the resulting effects on GHG emissions during a 150-d incubation period. Composting decreased the amount of organic compounds that could be thermally released from the biochars and affected their molecular nature. These thermally desorbable organic compounds from initial biochars likely stimulated the oxidation of CH and inhibited the production of NO in soil-biochar mixtures. However, these reductions of GHG emissions disappeared together with thermally desorbable organic compounds after the composting of chars. Instead, addition of composted gasification coke and charcoal stimulated the formation of CH and increased NO emissions by 45 to 56%. Nitrous oxide emissions equaled 20% of the total amount of N added with composted biochars, suggesting that organic compounds and N sorbed by the chars during composting fueled GHG production. The transient nature of the suppression of CH and NO production challenges the long-term GHG mitigation potential of biochar in soil. PMID:25602826

  16. Condensation Heat Transfer Inside Smooth Horizontal Tubes for R-22 and R-32\\/125 Mixture

    Microsoft Academic Search

    M. S. Chitti; N. K. Anand

    1996-01-01

    Regionally averaged heat transfer coefficients (h) for forced convective condensation inside smooth horizontal tubes were experimentally determined for an R-32\\/125 azeotropic mixture (50% by mass). A twophase test loop was built and calibrated using R-22. The refrigerant was condensed in a 6.1 m (20 ft.) long, 8 mm (0.315 inch) ID copper tube by water in the annulus of a

  17. Molecular composition of aged secondary organic aerosol generated from a mixture of biogenic volatile compounds using ultrahigh resolution mass spectrometry

    NASA Astrophysics Data System (ADS)

    Kourtchev, I.; Doussin, J.-F.; Giorio, C.; Mahon, B.; Wilson, E. M.; Maurin, N.; Pangui, E.; Venables, D. S.; Wenger, J. C.; Kalberer, M.

    2015-02-01

    Field observations over the past decade indicate that a significant fraction of organic aerosol in remote areas may contain highly oxidised molecules. Aerosol processing or further oxidation (ageing) of organic aerosol has been suggested to be responsible for their formation through heterogeneous uptake of oxidants and multigenerational oxidation of vapours by OH radicals. In this study we investigated the influence of several ageing processes on the molecular composition of secondary organic aerosols (SOA) using direct infusion and liquid chromatography ultrahigh resolution mass spectrometry. SOA was formed in simulation chamber experiments from ozonolysis of a mixture of four biogenic volatile organic compounds (BVOC): ?-pinene, ?-pinene, ?3-carene and isoprene. The SOA was subsequently aged under three different sets of conditions: in the dark in the presence of residual ozone, with UV irradiation and OH radicals, and using UV light only. Among all studied conditions, only OH radical-initiated ageing was found to influence the molecular composition of the aerosol and showed an increase in carbon oxidation state (OSC) and elemental O/C ratios of the SOA components. None of the ageing processes produced an observable effect on the oligomers formed from ozonolysis of the BVOC mixture, which were found to be equally abundant in both "fresh" and "aged" SOA. Additional experiments using ?-pinene as the sole precursor demonstrated that oligomers are an important group of compounds in SOA produced from both ozonolysis and OH radical-initiated oxidation processes; however, a completely different set of oligomers is formed under these two oxidation regimes. SOA from the OH radical-initiated ?-pinene oxidation had a significantly higher overall OSC and O/C compared to that from pure ozonolysis experiments confirming that the OH radical reaction is more likely to be responsible for the occurrence of highly oxidised species in ambient biogenic SOA.

  18. Time Dependence of Blood Concentrations during and after Exposure to a Mixture of Volatile Organic Compounds

    Microsoft Academic Search

    David L. Ashley; James D. Prah

    1997-01-01

    Volatile organic compounds constitute a group of important environmental pollutants that have been associated with the constellation of symptoms known as sick building syndrome. An understanding of the kinetics of uptake and elimination of volatile organic compounds is important for the proper interpretation of the internal dose concentrations of people exposed to these compounds. Blood concentrations measured before, during, and

  19. High resolution mass spectrometry for the characterization of complex, fossil organic mixtures

    SciTech Connect

    Winans, R.E.; Haas, G.W.; Kim, Y.L.; Hunt, J.E. [Argonne National Lab., IL (United States)

    1995-12-31

    The nature of molecules with heteroatom functionality in the pyridine, extracts of the Argonne Premium Coal Samples is being explored using high resolution mass spectrometry (FIRMS), with desorption chemical ionization (DCI). Structural information is obtained from tandem MS experiments using high resolution to select the ions to fragment. The first DCIHRMS spectra of complex mixtures are shown. Molecular weight distribution determined by DO are similar to those determined by laser desorption and field ionization mass spectrometry with very little ion intensity observed at greater than 1000 Daltons. Results are correlated with other techniques such as NMR, XPS, and XANES.

  20. Renal and hepatotoxic alterations in adult mice on inhalation of specific mixture of organic solvents.

    PubMed

    Vaghasia, Ketan K; Bhavyata, Kalariya; Linzbuoy, George; Hyacinth, Highland N

    2013-05-01

    This study was aimed at investigating alterations in renal and hepatic toxicity induced by exposing to a combination of three solvents, namely, benzene, toluene and xylene in adult mice. The mice were divided into three groups (control, low-dose-treated (450 ppm) and high-dose (675 ppm) groups) using randomization methods. The treated groups were exposed to vapours of a mixture of benzene, toluene and xylene at doses of 450 and 675 ppm, for 6 h day(-1) for a short-term of 7-day exposure period. The study revealed that the solvent exposure resulted in an increase in the weight of liver and kidney as compared to the control. Biochemical analyses indicated a significant decline in the activities of superoxide dismutase and catalase in both the treated groups, with concomitant increase in lipid peroxidation. Liver aminotransferases (alanine aminotransferase and aspartate aminotransferase) were elevated with significant alterations in the levels of protein, creatinine and cholesterol in these tissues upon solvent exposure. Correlated with these changes, serum thyroid hormones T3 and T4 were also significantly altered. This study, therefore, demonstrates that inhalation of vapours from the solvent mixture resulted in significant dose-dependent biochemical and functional changes in the vital tissues (liver and kidney) studied. The study has specific relevance since humans are increasingly being exposed to such solvents due to increased industrial use in such combinations. PMID:23637306

  1. NEUROTOXIC EFFECTS OF CONTROLLED EXPOSURE TO A COMPLEX MIXTURE OF VOLATILE ORGANIC COMPOUNDS

    EPA Science Inventory

    Subjective reactions of discomfort, impaired air quality, irritation of mucosal membranes, and impaired memory have been reported in chemically sensitive subjects during exposure to volatile organic compounds (VOC's) found in new buildings. 6 normal healthy male subjects aged 18-...

  2. Organic carbon aerogels from the sol-gel polymerization of phenolic-furfural mixtures

    DOEpatents

    Pekala, R.W.

    1998-04-28

    The sol-gel polymerization of a phenolic-furfural mixture in dilute solution leads to a highly cross-linked network that can be supercritically dried to form a high surface area foam. These porous materials have cell/pore sizes {<=}1000 {angstrom}, and although they are dark brown in color, they can be classified as a new type of aerogel. The phenolic-furfural aerogel can be pyrolyzed in an inert atmosphere at 1050 C to produce carbon aerogels. This new aerogel may be used for thermal insulation, chromatographic packing, water filtration, ion-exchange, and carbon electrodes for energy storage devices, such as batteries and double-layer capacitors. 8 figs.

  3. Organic aerogels from the sol-gel polymerization of phenolic-furfural mixtures

    DOEpatents

    Pekala, Richard W. (Pleasant Hill, CA)

    1996-01-01

    The sol-gel polymerization of a phenolic-furfural mixture in dilute solution leads to a highly cross-linked network that can be supercritically dried to form a high surface area foam. These porous materials have cell/pore sizes .ltoreq.1000.ANG., and although they are dark brown in color, they can be classified as a new type of aerogel. The phenolic-furfural aerogel can be pyrolyzed in an inert atmosphere at 1050.degree. C. to produce carbon aerogels. This new aerogel may be used for thermal insulation, chromatographic packing, water filtration, ion-exchange, and carbon electrodes for energy storage devices, such as batteries and double-layer capacitors.

  4. Organic aerogels from the sol-gel polymerization of phenolic-furfural mixtures

    DOEpatents

    Pekala, Richard W. (Pleasant Hill, CA)

    1995-01-01

    The sol-gel polymerization of a phenolic-furfural mixture in dilute solution leads to a highly cross-linked network that can be supercritically dried to form a high surface area foam. These porous materials have cell/pore sizes.ltoreq.1000.ANG., and although they are dark brown in color, they can be classified as a new type of aerogel. The phenolic-furfural aerogel can be pyrolyzed in an inert atmosphere at 1050.degree. C. to produce carbon aerogels. This new aerogel may be used for thermal insulation, chromatographic packing, water filtration, ion-exchange, and carbon electrodes for energy storage devices, such as batteries and double-layer capacitors.

  5. Organic aerogels from the sol-gel polymerization of phenolic-furfural mixtures

    DOEpatents

    Pekala, R.W.

    1995-12-19

    The sol-gel polymerization of a phenolic-furfural mixture in dilute solution leads to a highly cross-linked network that can be supercritically dried to form a high surface area foam. These porous materials have cell/pore sizes{<=}1000{angstrom}, and although they are dark brown in color, they can be classified as a new type of aerogel. The phenolic-furfural aerogel can be pyrolyzed in an inert atmosphere at 1050 C to produce carbon aerogels. This new aerogel may be used for thermal insulation, chromatographic packing, water filtration, ion-exchange, and carbon electrodes for energy storage devices, such as batteries and double-layer capacitors. 8 figs.

  6. Organic aerogels from the sol-gel polymerization of phenolic-furfural mixtures

    DOEpatents

    Pekala, R.W.

    1996-09-17

    The sol-gel polymerization of a phenolic-furfural mixture in dilute solution leads to a highly cross-linked network that can be supercritically dried to form a high surface area foam. These porous materials have cell/pore sizes {<=}1,000{angstrom}, and although they are dark brown in color, they can be classified as a new type of aerogel. The phenolic-furfural aerogel can be pyrolyzed in an inert atmosphere at 1,050 C to produce carbon aerogels. This new aerogel may be used for thermal insulation, chromatographic packing, water filtration, ion-exchange, and carbon electrodes for energy storage devices, such as batteries and double-layer capacitors. 8 figs.

  7. A NEW MASS SPECTROMETRIC TECHNIQUE FOR IDENTIFYING TRACE-LEVEL ORGANIC COMPOUNDS IN COMPLEX MIXTURES

    EPA Science Inventory

    Most organic compounds are not found in mass spectral libraries and cannot be easily identified from low resolution mass spectra. Ion Composition Elucidation (ICE) utilizes selected ion recording with a double focusing mass spectrometer in a new way to determine exact mas...

  8. Nitric acid-organic mixtures surveyed for use in separation by anion exchange methods

    NASA Technical Reports Server (NTRS)

    Bloomquist, C. A. A.; Faris, J. P.; Stewart, D. C.

    1968-01-01

    Column elution-spectrographic analysis technique compares certain solvents directly to the methanol system, using inert rare earths instead of actinides. Distribution ratios for americium between 90 percent solvent, 10 percent 5 M nitric acid and Dowex 1 nitrate form resin for a large group of organics miscible in water was determined.

  9. Measuring the dielectric properties of soil-organic mixtures using coaxial impedance dielectric reflectometry

    NASA Astrophysics Data System (ADS)

    Francisca, Franco M.; Montoro, Marcos A.

    2012-05-01

    Contamination of soils with non-aqueous phase liquids (NAPLs) is frequently produced by accidental spills and storage tanks or pipes leakage. The main goals dealing with soil and groundwater contamination include determining the extension of the affected zone, monitoring the contaminant plume and quantifying the pollution degree. The objective of this work is to evaluate the potential of dielectric permittivity measurements to detect the presence of NAPLs in sands. Tested samples were fine, medium, coarse and silty sand with different volumetric contents of water and paraffin oil. The dielectric permittivity was measured by means of a Coaxial Impedance Dielectric Reflectometry method in specimens with either known fluid content or at different stages during immiscible displacement tests. A simplified method was developed to quantify the amount of oil from dielectric permittivity measurements and effective mixture media models. Obtained results showed that groundwater contamination with NAPL and the monitoring of immiscible fluid displacement in saturated porous media can be clearly identified from dielectric measurements. Finally, very accurate results can be obtained when computing the contamination degree with the proposed method in comparison with the real volumetric content of NAPL (r2 > 90%).

  10. Nonthermal plasma alternative to the incineration of hazardous organic wastes. [Mixtures containing oil and trichloroethylene, carbon tetrachloride and trichloroethane

    SciTech Connect

    Rosocha, L.A.; McCulla, W.H.; Anderson, G.K.; Coogan, J.J.; Kang, M.; Tennant, R.A.; Wantuck, P.J.

    1992-01-01

    We are developing silent discharge plasma (SDP) oxidation technology as an alternative to incineration and as a post-incinerator treatment process for hazardous organic wastes. As an alternative to incineration, SDP apparatus has been coupled to a high-temperature packed-bed reactor, the plasma apparatus serving as a second stage for treating gaseous effluent from the packed bed. As a post- incinerator treatment process, SDP apparatus has been evaluated using a prepared gaseous feed containing hazardous organic compounds which are expected to be found in the machining fluids (trichloroethylene (TCE), carbon tetrachloride (CCl{sub 4}), and trichloroethane (TCA)). In typical tests with the packed-bed reactor alone, we have treated mixtures containing oil and several per cent TCE, TCA, or CCl{sub 4} removing the chlorocarbons to levels of ppm-order for TCA and to order {approximately}100 ppb for TCE and CCl{sub 4}, as measured in the gaseous effluent. In representative stand-alone tests with the SDP reactor, we have removed TCE in the gaseous influent from 1,000 ppm concentrations to around 100 ppb in the gaseous effluent (CCl{sub 4} appears to be more treatment-resistant). The measured figures of merit for the SDP reactor (electrical energy per mass of removed chemical) are 10's of kW-hr/kg for >>99% removal of TCE and 100's of kW-hr/kg for 90% removal of CCl{sub 4}, both being non-optimized cases in terms of waste concentration, carrier gas composition, water content, flow rate, and electrical power. Using combined packed- bed/SDP reactors on chlorocarbon/oil mixtures, several per cent chlorocarbon concentrations have been removed to well below the 100-ppb level overall. We envision eventual reductions to levels of {approximately}10 ppb or less.

  11. Evaluations of an Enhanced Total Hydrocarbon Analyzer With Complex Mixtures of Volatile Organic Compounds

    NASA Technical Reports Server (NTRS)

    Cross, John H.; Limero, Thomas F.; James, John T.; Breach, James; Hinton, Mark

    1995-01-01

    From the earliest manned missions, the volatile organic compound (VOC) content of spacecraft air has been a concern because of a much greater potential for contamination than air in most terrestrial settings. First, the volume of air is small compared to the mass of man- made materials comprising the interior furnishings of the spacecraft. These man-made materials offgas VOCs trapped during manufacture. Second, the nitrogen fraction of the air is recycled. Any VOCs not scrubbed out with charcoal filters or aqueous condensate (mainly water expired by the crew) will accumulate in the air. Third, the crew emits metabolic VOCs. Fourth, experimental payloads can also offgas or accidentally release a VOC; in fact a major organic constituent of the atmosphere is the disinfectant isopropanol released from swabs used in medical experiments.

  12. Enhanced solubilization of a metal-organic contaminant mixture (Pb, Sr, Zn, and perchloroethylene) by cyclodextrin.

    PubMed

    Skold, Magnus E; Thyne, Geoffrey D; Drexler, John W; Macalady, Donald L; McCray, John E

    2008-12-01

    Prior work has suggested that (carboxymethyl)-beta-cyclodextrin (CMCD) is capable of simultaneously enhancing the solubility of organics and metals, but sparse experimental data and no theoretical models have been published on this process. Preciously, a geochemical model for metal complexation by CMCD was formulated using PHREEQC on the basis of conditional stability constants measured in experiments using single-metal salts. In this study, the model is expanded to simultaneous metal and organic (perchloroethylene, PCE) complexation by CMCD. Experiments to verify the application of the formulation to mixed-waste systems were performed using solutions containing multiple metal ions (Pb, Sr, and Zn) and in a separate experiment introducing PCE with multiple metal ions. These experimental results show simultaneous solubility enhancement of metals and PCE. For solutions up to about 50 g/L CMCD, the model accurately predicted the simultaneous solubility enhancement for PCE, Pb, and Zn, while the difference between the measured and predicted Sr concentrations was accurate to within 15%. At CMCD concentrations greater than 50 g/L, the observed metal solubilities were greater than predicted (10% for Pb and Zn), probably due to the difficulty in accurately representing the activity and the effect on the ionic strength of functional groups on large organic molecules at higher concentrations. PMID:19192820

  13. Methods of analysis for complex organic aerosol mixtures from urban emission sources of particulate carbon

    SciTech Connect

    Mazurek, M.A. (Brookhaven National Lab., Upton, NY (United States)); Hildemann, L.M. (Stanford Univ., CA (United States). Dept. of Civil Engineering); Cass, G.R.; Rogge, W.F. (California Inst. of Tech., Pasadena, CA (United States)); Simoneit, B.R.T. (Oregon State Univ., Corvallis, OR (United States). Coll. of Oceanography)

    1990-10-01

    Organic aerosols comprise approximately 30% by mass of the total fine particulate matter present in urban atmospheres. The chemical composition of such aerosols is complex and reflects input from multiple sources of primary emissions to the atmosphere, as well as from secondary production of carbonaceous aerosol species via photochemical reactions. To identify discrete sources of fine carbonaceous particles in urban atmospheres, analytical methods must reconcile both bulk chemical and molecular properties of the total carbonaceous aerosol fraction. This paper presents an overview of the analytical protocol developed and used in a study of the major sources of fine carbon particles emitted to an urban atmosphere. 23 refs., 1 fig., 2 tabs.

  14. Supplemental Information to "Modeling the surface tension of complex, reactive organic-inorganic mixtures"

    E-print Network

    Meskhidze, Nicholas

    (kg H2O (mol C)-1 ) * Acetaldehyde 72.5 0.003 ± 2.1×10-3 1281 ± 4450 * Acetaldehyde in 3.1 M (NH4)2SO4 using Eqn. (5). Organic k Acetaldehyde -0.36 ± 0.02 Methylglyoxal -2.34 ± 0.05 Alanine 1.04 ± 0.92 ± 0.10 Formaldehyde -0.31 ± 0.02 Glyoxal 0.07 ± 0.04 #12;Figure S1. 0.05 M acetaldehyde with varying

  15. A chromatographic method to analyze products from photo-oxidation of anthropogenic and biogenic mixtures of volatile organic compounds in smog chambers.

    PubMed

    Pindado Jiménez, Oscar; Pérez Pastor, Rosa M; Vivanco, Marta G; Santiago Aladro, Manuel

    2013-03-15

    A method for quantifying secondary organic aerosol compounds (SOA) and water soluble secondary organic aerosol compounds (WSOA) produced from photo-oxidation of complex mixtures of volatile organic compounds (VOCs) in smog chambers by gas chromatography/mass spectrometry (GC/MS) has been developed. This method employs a double extraction with water and methanol jointly to a double derivatization with N,O-bis (trimethylsilil) trifluoroacetamide (BSTFA) and O-(2,3,4,5,6)-pentafluorobenzyl-hydroxylamine hydrochloride (PFBHA) followed by an analysis performed by GC/MS. The analytical procedure complements other methodologies because it can analyze SOA and WSOA compounds simultaneously at trace levels. As application, the methodology was employed to quantify the organic composition of aerosols formed in a smog chamber as a result of photo-oxidation of two different mixtures of volatile organic compounds: an anthropogenic mixture and a biogenic mixture. The analytical method allowed us to quantify up to 17 SOA compounds at levels higher than 20 ng m(-3) with reasonable recovery and a precision below 11%. Values found for applicability, selectivity, linearity, precision, recovery, detection limit, quantification limit and sensitivity demonstrated that the methodology can be satisfactorily applied to quantify SOA and WSOA. PMID:23598091

  16. Computer simulation of solid-liquid coexistence in binary hard sphere mixtures

    NASA Astrophysics Data System (ADS)

    Kranendonk, W. G. T.; Frenkel, D.

    We present the results of a computer simulation study of the solid-liquid coexistence of a binary hard sphere mixture for diameter ratios in the range 0·85 ? ?a ? 1>·00. For the solid phase we only consider substitutionally disordered FCC and HCP crystals. For 0·9425 < ? < 1·00 we find a solid-liquid coexistence curve of the 'spindle' type. For ? = 0·9425 this becomes an azeotropic and for ? = 0·875 a eutectic diagram. We compare these results with the predictions of the density functional theory of Barrat, Baus and Hansen. We observe that the density functional theory accurately predicts the point where the spindle diagram transforms into an azeotrope. However, the density functional theory differs from the simulation results on a number of counts. The greatest differences between computer simulations and theory are that the changeover from an azeotropic to a eutectic diagram is found to occur at ? = 0·875, rather than at the predicted value of ? = 0·92, that the density difference between the solid and the liquid at liquid-solid coexistence is found to have a minimum as a function of the mole fraction of the large spheres, while density functional theory predicts a maximum, and finally that the solubility of large spheres in a solid mixture of small spheres is much larger than predicted.

  17. The Challenge of Peat Substitution in Organic Seedling Production: Optimization of Growing Media Formulation through Mixture Design and Response Surface Analysis

    PubMed Central

    Ceglie, Francesco Giovanni; Bustamante, Maria Angeles; Ben Amara, Mouna; Tittarelli, Fabio

    2015-01-01

    Peat replacement is an increasing demand in containerized and transplant production, due to the environmental constraints associated to peat use. However, despite the wide information concerning the use of alternative materials as substrates, it is very complex to establish the best materials and mixtures. This work evaluates the use of mixture design and surface response methodology in a peat substitution experiment using two alternative materials (green compost and palm fibre trunk waste) for transplant production of tomato (Lycopersicon esculentum Mill.); melon, (Cucumis melo L.); and lettuce (Lactuca sativa L.) in organic farming conditions. In general, the substrates showed suitable properties for their use in seedling production, showing the best plant response the mixture of 20% green compost, 39% palm fibre and 31% peat. The mixture design and applied response surface methodology has shown to be an useful approach to optimize substrate formulations in peat substitution experiments to standardize plant responses. PMID:26070163

  18. Exergoeconomic analysis and optimization of an evaporator for a binary mixture of fluids in an organic Rankine cycle

    NASA Astrophysics Data System (ADS)

    Li, You-Rong; Du, Mei-Tang; Wang, Jian-Ning

    2012-12-01

    This paper focuses on the research of an evaporator with a binary mixture of organic working fluids in the organic Rankine cycle. Exergoeconomic analysis and performance optimization were performed based on the first and second laws of thermodynamics, and the exergoeconomic theory. The annual total cost per unit heat transfer rate was introduced as the objective function. In this model, the exergy loss cost caused by the heat transfer irreversibility and the capital cost were taken into account; however, the exergy loss due to the frictional pressure drops, heat dissipation to surroundings, and the flow imbalance were neglected. The variation laws of the annual total cost with respect to the number of transfer units and the temperature ratios were presented. Optimal design parameters that minimize the objective function had been obtained, and the effects of some important dimensionless parameters on the optimal performances had also been discussed for three types of evaporator flow arrangements. In addition, optimal design parameters of evaporators were compared with those of condensers.

  19. Kinetics of organic molecules in pulsed plasmas of nitrogen or N2/O2 mixtures at near atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Pasquiers, S.; Blin-Simiand, N.; Magne, L.

    2013-12-01

    In plasmas of atmospheric gases, the kinetics of some aliphatic organic molecules belonging to the hydrocarbons (propene, propane), aldehydes (acetaldehyde) and ketones (acetone) families were studied using a photo-triggered discharge (homogeneous plasma). It was shown that quenchings of N2 metastable states, A\\,^{3}\\Sigma_{u}^{+} and the group of singlets a'\\,^{1}\\Sigma_{u}^{-} , a 1?g and w 1?u, are important processes for the decomposition of such molecules. It plays a fundamental role in the nitrogen plasma, but it is also present in air. At low temperature, the oxidation reactions by the oxygen atom or by the hydroxyl radical are not always sufficiently effective to induce an increase of the molecule decomposition when oxygen is added to the nitrogen/organic mixture. For most cases, quenching processes appear purely dissociative. However, recent results obtained for propene lead to the conclusion that a non-dissociative exit route could exist. The quenching of the singlet states induces a break of the double bound C = O for the acetaldehyde and acetone molecules. Some kinetic analogies appear between filamentary and homogeneous plasmas, which could be very useful to get a comprehensive understanding of the physico-chemical processes in dielectric barriers or corona discharges used for various applications.

  20. Schiff base ligands and their transition metal complexes in the mixtures of ionic liquid + organic solvent: a thermodynamic study.

    PubMed

    Shekaari, Hemayat; Kazempour, Amir; Khoshalhan, Maryam

    2015-01-21

    Schiff bases and their metal complexes in the mixtures of ionic liquid (IL) + organic solvent have shown great potential in attractive oxidation catalytic processes. The efficiency of such a process is strongly dependent on the various molecular interactions occurring between components. Thermodynamic properties of these systems can provide valuable information about structural interactions. Therefore, in this work, the interactions of the IL 1-hexyl-3-methylimidazolium chloride ([HMIm]Cl) with Schiff bases in organic solvents were studied through the measurements of density, viscosity, and electrical conductivity. The effect of solvent on the interactions was examined by the solutions of IL + BPIC Schiff base + solvent (C2H6O-C3H8O-C4H10O). Moreover, the influence of Schiff base ligand and Schiff base complex structures was probed by the solutions of IL + DMA + ligand (salcn/salpr/salen) and IL + DMA + complex (VO(3-OMe-salen)/VO(salophen)/VO(salen)), respectively. Using the experimental data, some important thermodynamic properties, such as standard partial molar volume (V(0)(?,IL)), experimental slope (Sv), viscosity B-coefficient, solvation number (B/V(0)(?,IL) and limiting molar conductivity (?0) were calculated and discussed in terms of solute-solvent (IL-DMF/alcohol) and solute-cosolute (IL-Schiff base) interactions. PMID:25482659

  1. The Effect of Circuiting Arrangement on the Thermal Performance of Refrigeration Mixtures in Tube-and-Fin Condensing Heat Exchangers

    Microsoft Academic Search

    D. T. Chen; J. C. Conklin

    1999-01-01

    For the pure or azeotropic refrigerants typically used in;\\u000apresent air conditioning and refrigeration applications, the;\\u000arefrigerant changes phase at a constant temperature. Thus, the;\\u000arefrigerant circuiting arrangement such as crossfiow,;\\u000acounterfiow, or cross-counterflow, has no effect on the thermal;\\u000aperformance. For zeotropic refrigerant mixtures, however, the;\\u000aphase-change occurs over a temperature range, or \\

  2. Accumulation and effects of natural mixtures of persistent organic pollutants (POP) in Zebrafish after two generations of exposure.

    PubMed

    Berg, Vidar; Lyche, Jan L; Karlsson, Camilla; Stavik, Benedicte; Nourizadeh-Lillabadi, Rasoul; Hårdnes, Nina; Skaare, Janneche Utne; Alestrøm, Peter; Lie, Elisabeth; Ropstad, Erik

    2011-01-01

    Effects of exposure to environmentally realistic mixtures of persistent organic pollutants (POP) harvested from aquatic ecosystems in Norway were studied in an in vivo zebrafish model. POP were extracted from burbot (Lota lota) liver from two separate lakes, Lake Losna and Lake Mjøsa, and exposed to zebrafish through the diet in a two-generation study. Effects on survival, growth, sex ratio, and timing of puberty were investigated. In addition, the biomarkers 7-ethoxyresorufin O-deethylase (EROD) and vitellogenin (Vtg) were measured. The ratios of contaminant levels in extracts collected from Lake Mjøsa:Lake Losna were 6, 10, and 270 for polychlorinated biphenyls (PCB), dichlorodiphenyltrichloroethanes (DDT), and polybrominated diphenyl ethers (PBDE), respectively. The concentration range of POP measured in zebrafish was lower than in burbot originating from Lake Mjøsa, but comparable to concentrations previously reported in humans and wildlife. The results showed that exposure to environmentally realistic mixtures of POP exerted a negative effect on survival of fish in both generations. The marked drop in survival during 9-20 days post fertilization (dpf) suggested that this period may be a critical window for development. In both generations an earlier onset of puberty was observed and a higher proportion of males than females was noted in exposed fish compared to controls. Suprising effects of exposure were found on body weight. In the first generation (F(0)), body weight was significantly higher in both exposure groups compared to controls, while in the next generation (F(1)) the same exposures were associated with a decrease in body weight. Zebrafish exposed to relatively low quantities of POP showed a significant induction of biomarkers (EROD and Vtg), while fish exposed to higher exposure doses did not demonstrate induction. PMID:21391088

  3. Secondary Organic Aerosol Formation from the Photooxidation of Complex Hydrocarbon Mixtures: Composition, effect of SO2, and Relevance to Ambient Aerosol

    Microsoft Academic Search

    J. D. Surratt; S. Gao; E. Knipping; E. Edgerton; M. Shahgoli; J. H. Seinfeld; E. Edney; T. Kleindiesnt; M. Lewandowski; J. Offenberg; M. Jaoui

    2005-01-01

    Secondary organic aerosol (SOA) formation from single hydrocarbon precursors is commonly studied in smog chamber experiments to obtain SOA yield and organic composition data. However, very few complex air mixture experiments have been conducted to simulate possible conditions in ambient atmospheres. A six-phase experiment involving various combinations of alpha-pinene, toluene, isoprene, and SO2 were irradiated in the EPA's dynamic smog

  4. Nitrogen transformation during organic waste composting by the Rutgers system and its effects on pH, EC and maturity of the composting mixtures

    Microsoft Academic Search

    M. A. Sánchez-Monedero; A. Roig; C. Paredes; M. P. Bernal

    2001-01-01

    The evolution of the different forms of nitrogen during the composting of several wastes was studied, as well as its relation to the pH, electrical conductivity and parameters of maturity of the composts obtained. Four mixtures were prepared from different organic materials: sewage sludge, municipal solid waste, brewery sludge, sorghum bagasse, cotton waste and pine bark. The evolution of the

  5. Formation of Secondary Organic Aerosol from Irradiated a -Pinene/Tolueme/NOx Mixtures and the Effect of Isoprene and Sulfur Dioxide

    EPA Science Inventory

    Secondary organic aerosol (SOA) was generated by irradiating a series of a-pinene/toluene/NOx mixtures in the absence and presence of isoprene or sulfur dioxide. The purpose of the experiment was to evaluate the extent to which chemical perturbations to this base-case (a-pinene/...

  6. Ionic liquids and deep eutectic mixtures: sustainable solvents for extraction processes.

    PubMed

    Pena-Pereira, Francisco; Namie?nik, Jacek

    2014-07-01

    In recent years, ionic liquids and deep eutectic mixtures have demonstrated great potential in extraction processes relevant to several scientific and technological activities. This review focuses on the applicability of these sustainable solvents in a variety of extraction techniques, including but not limited to liquid- and solid-phase (micro) extraction, microwave-assisted extraction, ultrasound-assisted extraction and pressurized liquid extraction. Selected applications of ionic liquids and deep eutectic mixtures on analytical method development, removal of environmental pollutants, selective isolation, and recovery of target compounds, purification of fuels, and azeotrope breaking are described and discussed. PMID:24811900

  7. CONTRIBUTIONS OF TOLUENE AND ¿ -PINENE TO SOA FORMED IN AN IRRADIATED TOLUENE/¿-PINENE/NOX/AIR MIXTURE: COMPARISON OF RESULTS USING 14C CONTENT AND SOA ORGANIC TRACER METHODS

    EPA Science Inventory

    An organic tracer method, recently proposed for estimating individual contributions of toluene and a-pinene to secondary organic aerosol (SOA) formation, was evaluated by conducting a laboratory study where a binary hydrocarbon mixture, containing the anthropogenic aromatic hydro...

  8. Evaluation of the COSHH Essentials Model with a Mixture of Organic Chemicals at a Medium-Sized Paint Producer

    PubMed Central

    Lee, Eun Gyung; Slaven, James; Bowen, Russell B.; Harper, Martin

    2011-01-01

    The Control of Substances Hazardous to Health (COSHH) Essentials model was evaluated using full-shift exposure measurements of five chemical components in a mixture [acetone, ethylbenzene, methyl ethyl ketone, toluene, and xylenes] at a medium-sized plant producing paint materials. Two tasks, batch-making and bucket-washing, were examined. Varying levels of control were already established in both tasks and the average exposures of individual chemicals were considerably lower than the regulatory and advisory 8-h standards. The average exposure fractions using the additive mixture formula were also less than unity (batch-making: 0.25, bucket-washing: 0.56) indicating the mixture of chemicals did not exceed the combined occupational exposure limit (OEL). The paper version of the COSHH Essentials model was used to calculate a predicted exposure range (PER) for each chemical according to different levels of control. The estimated PERs of the tested chemicals for both tasks did not show consistent agreement with exposure measurements when the comparison was made for each control method and this is believed to be because of the considerably different volatilities of the chemicals. Given the combination of health hazard and exposure potential components, the COSHH Essentials model recommended a control approach ‘special advice’ for both tasks, based on the potential reproductive hazard ascribed to toluene. This would not have been the same conclusion if some other chemical had been substituted (for example styrene, which has the same threshold limit value as toluene). Nevertheless, it was special advice, which had led to the combination of hygienic procedures in place at this plant. The probability of the combined exposure fractions exceeding unity was 0.0002 for the batch-making task indicating that the employees performing this task were most likely well protected below the OELs. Although the employees involved in the bucket-washing task had greater potential to exceed the threshold limit value of the mixture (P > 1 = 0.2375), the expected personal exposure after adjusting for the assigned protection factor for the respirators in use would be considerably lower (P > 1 = 0.0161). Thus, our findings suggested that the COSHH essentials model worked reasonably well for the volatile organic chemicals at the plant. However, it was difficult to override the reproductive hazard even though it was meant to be possible in principle. Further, it became apparent that an input of existing controls, which is not possible in the web-based model, may have allowed the model be more widely applicable. The experience of using the web-based COSHH Essentials model generated some suggestions to provide a more user-friendly tool to the model users who do not have expertise in occupational hygiene. PMID:21047985

  9. Self-Organization in Active Cytoskeletal Mixtures: Cilia-like Beating of Microtubule Bundles and Spontaneous Bulk Mixing

    NASA Astrophysics Data System (ADS)

    Sanchez, Tim

    This thesis discusses circularization and supercoiling of actin biofilaments, as well as the various examples of self-organization observed in a simple non-equilibrium system of microtubules, motor clusters, and a depletion agent (PEG). When the ends of an actin filament approach each other, annealing can occur, resulting in the assumption of a circular conformation. In order to facilitate this experimentally, we dramatically reduce the space available for the ends to explore by confining the filaments to a quasi-2D region. This is accomplished through the use of a depletion attraction. In addition to the pronounced effects of this topological ring constraint on the statistical fluctuations of the filaments, we also observe a spontaneous supercoiling transition in fluorescently labeled actin rings that is directly driven by illumination. To better understand this transition in natural twist, we investigate real-time twist of a filament trapped between two beads, held by optical traps. The main focus of this graduate work was on the behavior of non-equilibrium in vitro mixtures of microtubules, kinesin motor clusters, and a depletion agent. We observed several striking and distinct examples of self-organization on near-macroscopic length scales, due to the interactions of very simple components. First we investigate the driving mechanism behind the beating of biological cilia and flagella, and find that this beating functionality can be reproduced in our vastly simpler system. This occurs only when minimalist components are reconstituted: motors, biofilaments, elastic links to hold the filaments together, and a basal attachment. Beyond the cooperativity of the motors to produce oscillatory beating in individual bundles, we also observe that active bundles in close proximity can synchronize their beating to produce stable, periodic metachronal waves that propagate along the bundle array. By changing only the length distribution of the microtubules in our system, we find that basal attachments at the chamber edge no longer form. Rather, bundles become unstable and interact in bulk by merging, extending, buckling, breaking, and recombining. These interactions lead to the emergence of a steady-state bulk mixing process that causes the super-diffusive transport of tracer particles and enhanced mixing of fluid. This mixing bears some resemblance to other mixing processes, including the biological example of cytoplasmic streaming. Finally, we show that a qualitatively new example of self-organization occurs when these active mixtures are put into water droplets in oil-water emulsions. The MT bundles migrate to the oil-water interface, forming a 2D active nematic. This active nematic exhibits a host of emergent properties, including the unbinding of +1/2 and -1/2 nematic defects from each other. The internal stresses of these active nematics also cause droplets to be self-propelled, leading to the possibility of studying a system of spherical swimmers, where new examples of self-organized behavior may occur.

  10. Abiotic synthesis of high-molecular-weight organics from an inorganic gas mixture of carbon monoxide, ammonia, and water by 3 MeV proton irradiation

    NASA Astrophysics Data System (ADS)

    Takano, Yoshinori; Ohashi, Akihiro; Kaneko, Takeo; Kobayashi, Kensei

    2004-02-01

    The abiotic formation of high-molecular-weight organics from an inorganic gas mixture of carbon monoxide, ammonia, and water as a result of 3 MeV proton irradiation from a Van de Graaff accelerator was experimentally verified. The inorganic gas mixture was simulated for representative of interstellar medium. The irradiation products included amino acid (AA) precursors, and the molecular weight distribution ranged from several hundred to a maximum of 3000 Da. Both proteinous and nonproteinous AAs were detected after acid hydrolysis. Thus, the primary irradiation products were not free AA analogs, but were AA precursors having high molecular weight. The present results have significant implications regarding the extraterrestrial origins of AA precursors, such as meteoritic organic compounds and the organic composition of interstellar dust particles.

  11. The structural organization of N-methyl-2-pyrrolidone + water mixtures: A densitometry, x-ray diffraction, and molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Usula, M.; Mocci, F.; Marincola, F. Cesare; Porcedda, S.; Gontrani, L.; Caminiti, R.

    2014-03-01

    A combined approach of molecular dynamics simulations, wide angle X-ray scattering experiments, and density measurements was employed to study the structural properties of N-methyl-2-pyrrolidone (NMP) + water mixtures over the whole concentration range. Remarkably, a very good agreement between computed and experimental densities and diffraction patterns was achieved, especially if the effect of the mixture composition on NMP charges is taken into account. Analysis of the intermolecular organization, as revealed by the radial and spatial distribution functions of relevant solvent atoms, nicely explained the density maximum observed experimentally.

  12. Influence of Seeding Ratio, Planting Date, and Termination Date on Rye-Hairy Vetch Cover Crop Mixture Performance under Organic Management.

    PubMed

    Lawson, Andrew; Cogger, Craig; Bary, Andy; Fortuna, Ann-Marie

    2015-01-01

    Cover crop benefits include nitrogen accumulation and retention, weed suppression, organic matter maintenance, and reduced erosion. Organic farmers need region-specific information on winter cover crop performance to effectively integrate cover crops into their crop rotations. Our research objective was to compare cover crop seeding mixtures, planting dates, and termination dates on performance of rye (Secale cereale L.) and hairy vetch (Vicia villosa Roth) monocultures and mixtures in the maritime Pacific Northwest USA. The study included four seed mixtures (100% hairy vetch, 25% rye-75% hairy vetch, 50% rye-50% hairy vetch, and 100% rye by seed weight), two planting dates, and two termination dates, using a split-split plot design with four replications over six years. Measurements included winter ground cover; stand composition; cover crop biomass, N concentration, and N uptake; and June soil NO3--N. Rye planted in mid-September and terminated in late April averaged 5.1 Mg ha-1 biomass, whereas mixtures averaged 4.1 Mg ha-1 and hairy vetch 2.3 Mg ha-1. Delaying planting by 2.5 weeks reduced average winter ground cover by 65%, biomass by 50%, and cover crop N accumulation by 40%. Similar reductions in biomass and N accumulation occurred for late March termination, compared with late April termination. Mixtures had less annual biomass variability than rye. Mixtures accumulated 103 kg ha-1 N and had mean C:N ratio <17:1 when planted in mid-September and terminated in late April. June soil NO3--N (0 to 30 cm depth) averaged 62 kg ha-1 for rye, 97 kg ha-1 for the mixtures, and 119 kg ha-1 for hairy vetch. Weeds comprised less of the mixtures biomass (20% weeds by weight at termination) compared with the monocultures (29%). Cover crop mixtures provided a balance between biomass accumulation and N concentration, more consistent biomass over the six-year study, and were more effective at reducing winter weeds compared with monocultures. PMID:26080008

  13. Influence of Seeding Ratio, Planting Date, and Termination Date on Rye-Hairy Vetch Cover Crop Mixture Performance under Organic Management

    PubMed Central

    Lawson, Andrew; Cogger, Craig; Bary, Andy; Fortuna, Ann-Marie

    2015-01-01

    Cover crop benefits include nitrogen accumulation and retention, weed suppression, organic matter maintenance, and reduced erosion. Organic farmers need region-specific information on winter cover crop performance to effectively integrate cover crops into their crop rotations. Our research objective was to compare cover crop seeding mixtures, planting dates, and termination dates on performance of rye (Secale cereale L.) and hairy vetch (Vicia villosa Roth) monocultures and mixtures in the maritime Pacific Northwest USA. The study included four seed mixtures (100% hairy vetch, 25% rye-75% hairy vetch, 50% rye-50% hairy vetch, and 100% rye by seed weight), two planting dates, and two termination dates, using a split-split plot design with four replications over six years. Measurements included winter ground cover; stand composition; cover crop biomass, N concentration, and N uptake; and June soil NO3--N. Rye planted in mid-September and terminated in late April averaged 5.1 Mg ha-1 biomass, whereas mixtures averaged 4.1 Mg ha-1 and hairy vetch 2.3 Mg ha-1. Delaying planting by 2.5 weeks reduced average winter ground cover by 65%, biomass by 50%, and cover crop N accumulation by 40%. Similar reductions in biomass and N accumulation occurred for late March termination, compared with late April termination. Mixtures had less annual biomass variability than rye. Mixtures accumulated 103 kg ha-1 N and had mean C:N ratio <17:1 when planted in mid-September and terminated in late April. June soil NO3--N (0 to 30 cm depth) averaged 62 kg ha-1 for rye, 97 kg ha-1 for the mixtures, and 119 kg ha-1 for hairy vetch. Weeds comprised less of the mixtures biomass (20% weeds by weight at termination) compared with the monocultures (29%). Cover crop mixtures provided a balance between biomass accumulation and N concentration, more consistent biomass over the six-year study, and were more effective at reducing winter weeds compared with monocultures. PMID:26080008

  14. Natural mixtures of persistent organic pollutants (POPs) suppress ovarian follicle development, liver vitellogenin immunostaining and hepatocyte proliferation in female zebrafish (Danio rerio).

    PubMed

    Kraugerud, Marianne; Doughty, Richard William; Lyche, Jan L; Berg, Vidar; Tremoen, Nina H; Alestrøm, Peter; Aleksandersen, Mona; Ropstad, Erik

    2012-07-15

    Persistent organic pollutants such as polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and dichlorodiphenyltrichloroethane (DDT) are present in high concentrations in livers of burbot (Lota lota) in Lake Mjøsa, Norway. In order to assess effects of such pollutants on fish gonadal morphology, female zebrafish were exposed in two generations by food to mixtures of pollutants extracted from livers of burbot from Lake Mjøsa (high and low dose) and Lake Losna, which represents background pollution, and compared to a control group. Ovarian follicle counts detected a significant decrease in late vitellogenic follicle stages in fish exposed to the Losna and the high concentrations of Mjøsa mixtures in fish from the first generation. In addition, proliferation of granulosa cells, visualized by immunohistochemistry against proliferating cell nuclear antigen (PCNA), was decreased in all exposure groups in either early or late vitellogenic follicle stages compared to control. This was accompanied by increased apoptosis of granulosa cells. There was a decrease in proliferation of liver hepatocytes with exposure to both Mjøsa mixtures. In addition, immunopositivity for vitellogenin in the liver was significantly lower in the Mjøsa high group than in the control group. When analysing effects of parental exposure, fish with parents exposed to Mjøsa high mixture had significantly higher numbers of perinucleolar follicles than fish with control parents. We conclude that long-term exposure of a real-life mixture of pollutants containing high- and background levels of chemicals supress ovarian follicle development, liver vitellogenin immunostaining intensity and hepatocyte proliferation in the zebrafish model. PMID:22459409

  15. Ignitability of Spray Clouds of Organic Solvents, Solvent\\/Water Mixtures, and Water-Based Paints by Electric Sparks, Arcs, and Open Flames

    Microsoft Academic Search

    Ulrich von Pidoll

    2008-01-01

    The ignitability of spray clouds of organic solvents, solvent\\/water mixtures, and water-based paints by electric discharges and open flames was investigated under worst-case conditions that typically apply to electrostatic paint spraying. More than 200 substances were sprayed with a high-rotation bell spraying device. Rotation speed, substance throughput, and shaping air were optimized in order to achieve an individual ignition optimum

  16. Mixtures of ionic liquid and organic carbonate as electrolyte with improved safety and performance for rechargeable lithium batteries

    Microsoft Academic Search

    R.-S. Kühnel; N. Böckenfeld; S. Passerini; M. Winter; A. Balducci

    2011-01-01

    In this paper we report the results of physical–chemical and electrochemical investigations performed on ternary mixtures of the room temperature ionic liquid (IL) N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR14TFSI), propylene carbonate (PC), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as electrolyte for lithium-ion batteries. The thermal stability, ionic conductivity, viscosity and electrochemical stability windows of all considered mixtures were investigated and compared with those of electrolytes

  17. Densities and vapor-liquid equilibria in binary mixtures formed by propyl methanoate + ethanol, + propan-1-ol, and + butan-1-ol at 160.0 kPa

    SciTech Connect

    Falcon, J.; Ortega, J.; Gonzalez, E. [Escuela Superior de Ingenieros Industriales, Las Palmas (Spain). Laboratorio de Termodinamica y Fisicoquimica] [Escuela Superior de Ingenieros Industriales, Las Palmas (Spain). Laboratorio de Termodinamica y Fisicoquimica

    1996-07-01

    Densities and excess volumes were determined at 298.15 K for propyl methanoate + ethanol, + propan-1-ol, and + butan-1-ol. The results of those quantities were then correlated to get the concentrations of vapor-liquid equilibrium obtained isobarically at 160 kPa for the same mixtures. Two mixtures show azeotropes: for propyl methanoate (1) + ethanol (2), x{sub 1} = 0.443 at T = 358.7 K; and for propyl methanoate (1) + propan-1-ol (2), x{sub 1} = 0.762 at T = 368.2 K. The mixtures are thermodynamically consistent, and the predictions made using several group-contribution models are satisfactory.

  18. Theoretical analysis for condensation heat transfer of binary refrigerant mixtures with annular flow in horizontal mini-tubes

    NASA Astrophysics Data System (ADS)

    Zhang, Hui-Yong; Li, Jun-Ming; Sun, Ji-Liang; Wang, Bu-Xuan

    2015-06-01

    A theoretical model is developed for condensation heat transfer of binary refrigerant mixtures in mini-tubes with diameter about 1.0 mm. Condensation heat transfer of R410A and R32/R134a mixtures at different mass fluxes and saturated temperatures are analyzed, assuming that the phase flow pattern is annular flow. The results indicate that there exists a maximum interface temperature at the beginning of condensation process for azeotropic and zeotropic mixtures and the corresponding vapor quality to the maximum value increases with mass flux. The effects of mass flux, heat flux, surface tension and tube diameter are analyzed. As expected, the condensation heat transfer coefficients increase with mass flux and vapor quality, and increase faster in high vapor quality region. It is found that the effects of heat flux and surface tension are not so obvious as that of tube diameter. The characteristics of condensation heat transfer of zeotropic mixtures are consistent to those of azeotropic refrigerant mixtures. The condensation heat transfer coefficients increase with the concentration of the less volatile component in binary mixtures.

  19. Natural mixtures of persistent organic pollutants (POP) increase weight gain, advance puberty, and induce changes in gene expression associated with steroid hormones and obesity in female zebrafish.

    PubMed

    Lyche, Jan L; Nourizadeh-Lillabadi, Rasoul; Almaas, Camilla; Stavik, Benedicte; Berg, Vidar; Skåre, Janneche Utne; Alestrøm, Peter; Ropstad, Erik

    2010-01-01

    In the present study, developmental and reproductive effects of lifelong exposure to environmental relevant concentrations of two natural mixtures of persistent organic pollutants (POP) were investigated using classical and molecular methods in a controlled zebrafish model. The mixtures used were extracted from burbot (Lota lota) liver originating from freshwater systems in Norway: one mixture with high levels and one mixture with background levels of polybrominated diphenyl ethers (PBDE), polychlorinated biphenyls (PCB), and dichlorodiphenyltrichloroethane metabolites (DDT). The concentration of POP measured in the zebrafish ranged from levels detected in wild fish from Lake Mjøsa to concentrations reported in human and wildlife populations, indicating that the experimental fish were exposed to concentrations comparable with wild fish. Phenotypic effects observed in both exposure groups included earlier onset of puberty, increased male/female sex ratio, and differences in body weight at 5 mo of age. Interestingly, genome-wide transcription profiling showed changes in regulation of genes involved in endocrine signaling and growth. The transcriptomics changes include key regulator genes for steroid hormone functions (ncoa3), and growth (c/ebp, ncoa3). The effects observed in the experimental zebrafish model raise the question whether chemical pollution represents a risk to reproductive health of wild fish inhabitating the freshwater system. PMID:20526952

  20. Transcriptional regulation in liver and testis associated with developmental and reproductive effects in male zebrafish exposed to natural mixtures of persistent organic pollutants (POP).

    PubMed

    Nourizadeh-Lillabadi, Rasoul; Lyche, Jan L; Almaas, Camilla; Stavik, Benedicte; Moe, S Jannicke; Aleksandersen, Mona; Berg, Vidar; Jakobsen, Kjetill S; Stenseth, Nils Chr; Skåre, Janneche Utne; Alestrøm, Peter; Ropstad, Erik

    2009-01-01

    Persistent organic pollutants (POP) occur as mixtures in nature and it is difficult to predict the toxicity of such mixtures based on knowledge about toxicity and mechanisms of action for single compounds. The present knowledge on the combined toxic effects and modes of actions of exposure to mixtures is limited. Thus, the scientifically based hazard and risk assessment of POP requires analytical and toxicological data from studies with environmental mixtures of POP. The application of genome wide transcription profiling in toxicology, in combination with classical endpoints, will improve the current understanding of the mechanisms of toxic processes. Furthermore, gene expression data may be useful in establishing new hypothesis and discovering new biomarkers for known toxicity as well as not yet recognized toxicity endpoints. In the present study, developmental and reproductive effects of lifelong exposure to environmental relevant concentrations of two natural mixtures of POP were investigated using classical and molecular methods in a controlled zebrafish model. The mixtures used were extracted from burbot (Lota lota) liver originating from freshwater systems in Norway: one mixture with high levels and one mixture with background levels of polybrominated diphenyl ethers (PBD), polychlorinated biphenyls (PCB), and DDT. The concentration of POP in the zebrafish ranged from levels detected in wild fish from Lake Mjøsa, to concentrations reported in human and wildlife populations. Phenotypic effects observed in both exposure groups included (1) reduced survival, (2) earlier onset of puberty, (3) increased male/female sex ratio, and (4) differences in body weight at 5 mo of age. Interestingly, genome-wide transcription profiling showed changes in regulation of genes involved in endocrine signaling and growth. The transcriptomics changes included (1) key regulator genes for steroid and thyroid hormone functions (cga, ncoa3), (2) insulin signaling and metabolic homeostasis (pik3r1, pfkfb3, ptb1), and (3) p53 activation (mdm4). The effects observed in the experimental zebrafish model raise the question of whether chemical pollution represents a risk to the reproductive health of wild fish inhabiting the freshwater system. PMID:19184727

  1. 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Polymer induced multiphase generation in water/organic solvent mixtures.

    E-print Network

    Loh, Watson

    PEO A B Polymer induced multiphase generation in water/organic solvent mixtures. Strategies towards the beginning of this century,1 that ternary mixtures of water and certain pairs of polymers of the polymers. The same phenomenon has been observed when some inorganic salts, like alkaline sulfates

  2. Correlating solubility parameters and solvatochromic parameters with the self-assembly of poly(3-hexylthiophene) in mixtures of organic solvents

    NASA Astrophysics Data System (ADS)

    Gordon, Madeleine; Boucher, David

    2015-03-01

    We have studied the assembly and crystallinity of poly(3-hexylthiophene) (P3HT) (Mn ~ 28.2 kDa, regioregularity > 96 %, PDI ~ 1.3) in >100 binary solvent mixtures using UV-Vis absorption spectroscopy, and it is clear that the identity of the poor solvent used to drive aggregation has a significant impact on the structural order and crystallinity of the P3HT aggregates in solution. Here we report our findings using Hansen solubility parameters (HSPs), specifically the solubility distance vector, Ra, and the Kamlet-Taft solvatochromic parameters of the solvent mixtures to better understand the dominant solvent forces driving the self assembly of P3HT. We find that the directionality of the Ra vector provides a better measure of the crystallinity of the P3HT assemblies formed in the solvent mixtures than does the magnitude of the Ra vector. Our analysis of the Kamlet-Taft (?, ?, ?*) and ET(30) solvatochromic parameters reveals that the ? parameter correlates best with the crystallinity of P3HT and that, in general, assemblies having higher structural order are formed in solvent mixtures with lower values of ?.

  3. Activity coefficient at infinite dilution, azeotropic data, excess enthalpies and solid–liquid-equilibria for binary systems of alkanes and aromatics with esters

    Microsoft Academic Search

    Eileen Collinet; Jürgen Gmehling

    2005-01-01

    Binary azeotropic data have been measured at different pressures for ethyl acetate+heptane, methyl acetate+heptane, isopropyl acetate+hexane and isopropyl acetate+heptane by means of a wire band column. Additionally activity coefficients at infinite dilution have been determined for ethyl acetate and isopropyl acetate in decane and dodecane in the temperature range between 303.15 and 333.15K with the help of the dilutor technique.

  4. Vapour–liquid equilibria, azeotropic data, excess enthalpies, activity coefficients at infinite dilution and solid–liquid equilibria for binary alcohol–ketone systems

    Microsoft Academic Search

    Rima Abbas; Jürgen Gmehling

    2008-01-01

    Isothermal vapour–liquid equilibria (VLE), solid–liquid equilibria and excess enthalpies have been measured for the systems cyclohexanone+cyclohexanol and 2-octanone+1-hexanol. Additionally in this paper binary azeotropic data at different pressures for 1-pentanol+2-heptanone and 1-hexanol+2-octanone have been determined with the help of a wire band column. Furthermore activity coefficients at infinite dilution for methanol, ethanol, 1-butanol and 1-propanol in 2-octanone at different temperatures

  5. Adsorption of a binary gas mixture which laterally interacts on a random heterogeneous surface

    SciTech Connect

    Ritter, J.A.

    1992-01-01

    Analytical expressions for the adsorption of a binary gas mixture which laterally interacts on a heterogeneous surface are developed. The lateral interactions are of the Bragg-Williams type and the surface heterogeneity is modeled via a random distribution of sites described by a uniform distribution of Henry's Law constants. The parametric study shows that complex phase behavior can be predicted, including azeotropes and sigmoidal shaped X-Y diagrams. Also, this model may be useful for modeling and designing adsorption processes as it requires few iterations to simultaneously solve the implicit and coupled algebraic expressions.

  6. Two-Phase Flow of Two HFC Refrigerant Mixtures Through Short Tube Orifices, Draft Final Report 

    E-print Network

    Payne, W. V.; O'Neal, D. L.

    1994-01-01

    for the ternary zeotrope and binary near-azeotrope were calculated based upon thermodynamic property data supplied by the refrigerant manufacturers. EPA Task 1 Drafl Report, Page No. 16 Table 2.2: Description of the Data Acquisition Sensor Channels. Channel... temperatures 95?F (35.0?C), 110?F (43.3"C), and 125?F (51.7"C) were selected for both the ternary and binary refrigerants. The corresponding upstream saturation pressures for the ternary mixture were 22 1 psia (1524.kPa), 27 1 psia (1870 kPa), and 329 psia...

  7. Decrease in the abundance and viability of oceanic phytoplankton due to trace levels of complex mixtures of organic pollutants

    Microsoft Academic Search

    Pedro Echeveste; Jordi Dachs; Naiara Berrojalbiz; Susana Agustí

    2010-01-01

    Long range atmospheric transport and deposition is a significant introduction pathway of organic pollutants to remote oceanic regions, leading to their subsequent accumulation in marine organisms. Persistent organic pollutants (POPs) bioconcentrate in planktonic food webs and these exert a biogeochemical control on the regional and global cycling of POPs. Therefore, an important issue is to determine whether the anthropogenic chemical

  8. Antimould activity of sourdough lactic acid bacteria: identification of a mixture of organic acids produced by Lactobacillus sanfrancisco CB1

    Microsoft Academic Search

    A. Corsetti; M. Gobbetti; J. Rossi; P. Damiani

    1998-01-01

    Sourdough lactic acid bacteria, cultivated in wheat flour hydrolysate, produced antimould compounds. The antimould activity\\u000a varied greatly among the strains and was mainly detected within obligately heterofermentative Lactobacillus spp. Among these, Lb. sanfrancisco CB1 had the largest spectrum. It inhibited moulds related to bread spoilage such as Fusarium, Penicillium, Aspergillus and Monilia. A mixture of acetic, caproic, formic, propionic, butyric

  9. Secondary Organic Aerosol Formation from the Photooxidation of Complex Hydrocarbon Mixtures: Composition, effect of SO2, and Relevance to Ambient Aerosol

    NASA Astrophysics Data System (ADS)

    Surratt, J. D.; Gao, S.; Knipping, E.; Edgerton, E.; Shahgoli, M.; Seinfeld, J. H.; Edney, E.; Kleindiesnt, T.; Lewandowski, M.; Offenberg, J.; Jaoui, M.

    2005-12-01

    Secondary organic aerosol (SOA) formation from single hydrocarbon precursors is commonly studied in smog chamber experiments to obtain SOA yield and organic composition data. However, very few complex air mixture experiments have been conducted to simulate possible conditions in ambient atmospheres. A six-phase experiment involving various combinations of alpha-pinene, toluene, isoprene, and SO2 were irradiated in the EPA's dynamic smog chamber at the National Exposure Research Laboratory in Raleigh, NC. Glass fiber filters and impactor plates were collected for each phase of the experiment to identify and quantify the nature of the SOA composition. The following suite of analytical techniques analyzed the resultant polar organic compounds and the high molecular weight species: liquid chromatography-electrospray ionization (ESI)-mass spectrometry, gas chromatography-mass spectrometry, ESI-ion trap mass spectrometry, matrix assisted laser desorption (MALDI)-time of flight mass spectrometry, and high-resolution mass spectrometry. When SO2 is present in the chamber, increases in the gravimetric aerosol mass concentration and in the abundance of polar organic compounds are observed, likely suggesting an acid catalysis effect stemming from the conversion of SO2 to H2SO4 that condenses onto aerosol formed. The addition of isoprene to a alpha-pinene/toluene mixture is found to lower the amount of aerosol produced and is also found to lower the abundance of organic compounds identified by the various analytical techniques. Lastly, many of the polar organic compounds identified and quantified here are also seen in the Southeastern Aerosol Research and Characterization (SEARCH) network during the summer of 2004. In particular, a sulfur and nitrogen containing organic species (MW = 295 gmol) is found to be the most abundant polar organic species identified in this field study (~28 % on average of the total identified organic mass). This species is also detected in the chamber experiment only when alpha-pinene and SO2 are both present in the chamber, suggesting that this abundant species is likely formed from monoterpene photooxidation. High-resolution mass spectrometry suggests the molecular formula for this species is C10H16NO7S.

  10. Deposition and characterization of organic polymer thin films using a dielectric barrier discharge with different C2Hm/N2 (m = 2, 4, 6) gas mixtures

    NASA Astrophysics Data System (ADS)

    Chandrashekaraiah, Thejaswini Halethimmanahally; Bogdanowicz, Robert; Danilov, Vladimir; Schäfer, Jan; Meichsner, Jürgen; Hippler, Rainer

    2015-06-01

    Organic polymer thin films have been deposited on Si(100) and aluminum coated glass substrates by a dielectric barrier discharge (DBD) operated at medium pressure using different C2H m /N2 ( m = 2, 4, 6) gas mixtures. The deposited films were characterized by various spectroscopic techniques. Fourier transform infrared reflection absorption spectroscopy (FT-IRRAS) revealed the chemical functional groups present in the films. The surface chemical compositions have been derived from X-ray photo electron spectroscopy (XPS). FT-IRRAS and XPS show the presence of sp, s p 2 and s p 3 bonds of carbon and nitrogen. Various functional groups such as NH containing, saturated and unsaturated alkyl groups have been identified. Thin films obtained from C2H2/N2 and C2H4/N2 gas mixtures revealed a higher N/C ratio when compared to thin films obtained from C2H6/N2. Thickness, refractive index and extinction coefficient were evaluated by spectroscopic ellipsometry (SE). Significant differences between the films obtained with different gas mixtures are observed.

  11. Deposition and characterization of organic polymer thin films using a dielectric barrier discharge with different C2Hm/N2 (m = 2, 4, 6) gas mixtures

    NASA Astrophysics Data System (ADS)

    Halethimmanahally Chandrashekaraiah, Thejaswini; Bogdanowicz, Robert; Danilov, Vladimir; Schäfer, Jan; Meichsner, Jürgen; Hippler, Rainer

    2015-06-01

    Organic polymer thin films have been deposited on Si(100) and aluminum coated glass substrates by a dielectric barrier discharge (DBD) operated at medium pressure using different C2Hm/N2 (m = 2, 4, 6) gas mixtures. The deposited films were characterized by various spectroscopic techniques. Fourier transform infrared reflection absorption spectroscopy (FT-IRRAS) revealed the chemical functional groups present in the films. The surface chemical compositions have been derived from X-ray photo electron spectroscopy (XPS). FT-IRRAS and XPS show the presence of sp, sp2 and sp3 bonds of carbon and nitrogen. Various functional groups such as NH containing, saturated and unsaturated alkyl groups have been identified. Thin films obtained from C2H2/N2 and C2H4/N2 gas mixtures revealed a higher N/C ratio when compared to thin films obtained from C2H6/N2. Thickness, refractive index and extinction coefficient were evaluated by spectroscopic ellipsometry (SE). Significant differences between the films obtained with different gas mixtures are observed.

  12. Efficiency of methods for Karl Fischer determination of water in oils based on oven evaporation and azeotropic distillation.

    PubMed

    Larsson, William; Jalbert, Jocelyn; Gilbert, Roland; Cedergren, Anders

    2003-03-15

    The efficiency of azeotropic distillation and oven evaporation techniques for trace determination of water in oils has recently been questioned by the National Institute of Standards and Technology (NIST), on the basis of measurements of the residual water found after the extraction step. The results were obtained by volumetric Karl Fischer (KF) titration in a medium containing a large excess of chloroform (> or = 65%), a proposed prerequisite to ensure complete release of water from the oil matrix. In this work, the extent of this residual water was studied by means of a direct zero-current potentiometric technique using a KF medium containing more than 80% chloroform, which is well above the concentration recommended by NIST. A procedure is described that makes it possible to correct the results for dilution errors as well as for chemical interference effects caused by the oil matrix. The corrected values were found to be in the range of 0.6-1.5 ppm, which should be compared with the 12-34 ppm (uncorrected values) reported by NIST for the same oils. From this, it is concluded that the volumetric KF method used by NIST gives results that are much too high. PMID:12659179

  13. The effect of humidity on the collection efficiencies of two monitoring methods when exposed to a mixture of organic solvents

    E-print Network

    Rushlow, Lori Ann

    1989-01-01

    for a period of time prior to the introduction of an organic solvent vapor. Charcoal tubes and passive dosimeters were exposed to three levels of humidity and three solvent concentrations. The samplers were exposed to a zero concentration... of the Exposure Chamber. . 22 Comparison of the Acetone Results for Charcoal Tubes and OVMs. 44 Page 3M 3500 Organic Vapor Monitor with Cover. . . 18 Figure 5 Comparison of the Toluene Results for Charcoal Tubes and OVMs. 45 INTRODUCTION Industrial hygiene...

  14. A predictive method for crude oil volatile organic compounds emission from soil: evaporation and diffusion behavior investigation of binary gas mixtures.

    PubMed

    Wang, Haijing; Fischer, Thomas; Wieprecht, Wolfgang; Möller, Detlev

    2015-05-01

    Due to their mobility and toxicity, crude oil volatile organic compounds (VOCs) are representative components for oil pipeline contaminated sites detection. Therefore, contaminated location risk assessment, with airborne light detection and ranging (LIDAR) survey, in particular, requires ground-based determinative methods for oil VOCs, the interaction between oil VOCs and soil, and information on how they diffuse from underground into atmosphere. First, we developed a method for determination of crude oil VOC binary mixtures (take n-pentane and n-hexane as examples), taking synergistic effects of VOC mixtures on polydimethylsiloxane (PDMS) solid-phase microextraction (SPME) fibers into consideration. Using this method, we further aim to extract VOCs from small volumes, for example, from soil pores, using a custom-made sampling device for nondestructive SPME fiber intrusion, and to study VOC transport through heterogeneous porous media. Second, specific surface Brunauer-Emmett-Teller (BET) analysis was conducted and used for estimation of VOC isotherm parameters in soil. Finally, two models were fitted for VOC emission prediction, and the results were compared to the experimental emission results. It was found that free diffusion mode worked well, and an empirical correction factor seems to be needed for the other model to adapt to our condition for single and binary systems. PMID:25572270

  15. Anion exchange of organic carboxylate by soils responsible for positive Km-fc relationship from methanol mixture.

    PubMed

    Kim, Minhee; Han, Junho; Hyun, Seunghun

    2013-09-01

    The cosolvency model was not applicable for predicting the sorption of organic carboxylic acids. The reason of inapplicability was investigated by analyzing the solubility (Sm) and sorption (Km) of benzoic acid, 2,4-dichlorophenoxyacetic acid (2,4-D), and 2,4,6-trichlorophenol (2,4,6-TCP). The Sm and Km by two iron-rich soils was measured as a function of methanol volume fraction (fc), electrolyte compositions, and pH(app). For 2,4,6-TCP, the Km of both neutral and anion species was well-explainable by the cosolvency model, exemplifying the knowledge of cosolvency power (?) being sufficient to describe its sorption. However, for benzoic acid and 2,4-D, the Km of organic anions increased with fc, illustrating the organic carboxylate to be responsible for the deviation. The Sm of organic anions was not affected by the ionic valence (Ca(2+) vs. K(+)) of liquid phase. Among hydrophilic quantities of the 2,4-D sorption, the fraction of anion exchange increased with fc while the fraction of Ca-bridge decreased in the same range. Adding solvent in soil-water system is likely to render soil surface charge more positive, fortifying the anion exchange, but opposing the formation of Ca-bridging. Therefore, it can be concluded that the positive Km-fc relationship is due to the anion exchange of organic carboxylate with positively charged soil surface, whose contribution is >50% of overall sorption at solvent-free system and becomes greater with fc up to 82%. PMID:23732008

  16. Hydrophobic treatment of organics against glass employing nonequilibrium atmospheric pressure pulsed plasmas with a mixture of CF{sub 4} and N{sub 2} gases

    SciTech Connect

    Inui, Hirotoshi; Takeda, Keigo; Ishikawa, Kenji; Sekine, Makoto; Hori, Masaru [Department of Electrical Engineering and Computer Science, Nagoya University, Aichi 464-8603 (Japan); Yara, Takuya; Uehara, Tsuyoshi [Sekisui Chemical Co., Ltd., Kyoto 601-8105 (Japan)

    2011-01-01

    A hydrophobic organics surface selectively against glass was realized by employing nonequilibrium atmospheric-pressure pulsed plasmas with a mixture of CF{sub 4} and N{sub 2} gases. The organic surface was drastically altered to have a high hydrophobicity, while the glass surface itself remained hydrophilic after the plasma treatment with the addition of a small amount of CF{sub 4} to the N{sub 2} gas. After 100 CF{sub 4}/N{sub 2} plasma treatments, no thin film deposition was observed on the organic material. To investigate the characteristics of the CF{sub 4}/N{sub 2} plasma, the exhaust gas from the plasma was measured by using ion attachment mass spectroscopy (IAMS). The IAMS spectrum indicated that the amounts of CF{sub 3} and F radicals were increased drastically with increasing addition of CF{sub 4}. A mechanism of the selective surface modification was clarified on a result of surface chemical bonding with the gas phase.

  17. A case study on co-exposure to a mixture of organic solvents in a Tunisian adhesive-producing company

    PubMed Central

    2011-01-01

    Objectives to assess environmental and biological monitoring of exposure to organic solvents in a glue-manufacturing company in Sfax, Tunisia. Methods Exposure of volunteer workers, in the solvented glue-work-stations, in the control laboratory and in the storage rooms of the finished products, was assessed through indoor-air and urine measurements. Informed consent of the workers was obtained. Results and discussion The exposure indexes were found with high values in the solvented workshop as well as in the control laboratory and were respectively, 8.40 and 3.12. These indexes were also correlated with hexane and toluene indoor air concentrations. As to urine, the obtained results for the 2,5-hexandione and hippuric acid, metabolites of hexane and toluene, respectively, were in accord with the indoor-air measurements, with an average of 0.46 mg/l and 1240 mg/g of creatinine. Conclusion This study assessed for the first time biological exposure to organic solvents used in Tunisian adhesive industries. Although values are likely to underestimate true exposure levels, some figures exceed European and American occupational exposure guidelines. PMID:22082240

  18. Greening pharmaceutical applications of liquid chromatography through using propylene carbonate-ethanol mixtures instead of acetonitrile as organic modifier in the mobile phases.

    PubMed

    Tache, Florentin; Udrescu, Stefan; Albu, Florin; Mic?le, Florina; Medvedovici, Andrei

    2013-03-01

    Substitution of acetonitrile (ACN) as organic modifier in mobile phases for liquid chromatography by mixtures of propylene carbonate (PC) and ethanol (EtOH) may be considered a greener approach for pharmaceutical applications. Such a replacement is achievable without any major compromise in terms of elution order, chromatographic retention, efficiency and peak symmetry. This has been equally demonstrated for reverse phase (RP), ion pair formation (IP) and hydrophilic interaction liquid chromatography (HILIC) separation modes. The impact on the sensitivity induced by the replacement between these organic solvents is discussed for UV-vis and mass spectrometric detection. A comparison between Van Deemter plots obtained under elution conditions based on ACN and PC/EtOH is presented. The alternative elution modes were also compared in terms of thermodynamic parameters, such as standard enthalpy (?H?) and entropic contributions to the partition between the mobile and the stationary phases, for some model compounds. Van't Hoff plots demonstrated that differences between the thermodynamic parameters are minor when shifting from ACN/water to PC/EtOH/water elution on an octadecyl chemically modified silicagel stationary phase. As long as large volume injection (LVI) of diluents non-miscible with the mobile phase is a recently developed topic having a high potential of greening the sample preparation procedures through elimination of the solvent evaporation stage, this feature was also assessed in the case of ACN replacement by PC/EtOH. PMID:23277155

  19. Annual and seasonal changes in mineral contents (Ca, Mg, P, K and Na) of grazed clover-grass mixtures in organic farming

    Microsoft Academic Search

    Eeva Kuusela

    2006-01-01

    A grazed field experiment was established in 1995 to evaluate alsike clover ( Trifoliun hybridum L.), red clover (Trifolium pratense L.) and white clover (Trifolium repens L.) in clover-grass mixtures under or- ganic farming practices. In this study the effect of seed mixture (alsike clover, red clover, white clover, white and alsike clover or grass mixture), year (1997, 1998) and

  20. Preyssler type heteropolyacid-incorporated highly water-selective sodium alginate-based inorganic–organic hybrid membranes for pervaporation dehydration of ethanol

    Microsoft Academic Search

    Veeresh T. Magalad; Amit R. Supale; Sanjeev P. Maradur; Gavisiddappa S. Gokavi; Tejraj M. Aminabhavi

    2010-01-01

    Sodium alginate (NaAlg) hybrid membranes containing 6, 8 and 10wt.% of Preyssler type heteropolyacid H14[NaP5W30O110] (HPA) were prepared and characterized by FTIR, SEM, TGA, DSC, UTM and contact angle measurements. Hybrid membranes were more hydrophilic than pristine NaAlg membrane and exhibited increased pervaporation separation index (PSI) for selectively separating water from the azeotropic mixture (4wt.% water+96wt.% ethanol) with ethanol. The

  1. Aggregation behavior of sodium lauryl ether sulfate with a positively bicharged organic salt and effects of the mixture on fluorescent properties of conjugated polyelectrolytes.

    PubMed

    Tang, Yongqiang; Liu, Zhang; Zhu, Linyi; Han, Yuchun; Wang, Yilin

    2015-02-24

    The aggregation behavior of anionic single-chain surfactant sodium lauryl ether sulfate containing three ether groups (SLE3S) with positively bicharged organic salt 1,2-bis(2-benzylammoniumethoxy)ethane dichloride (BEO) has been investigated in aqueous solution, and the effects of the BEO/SLE3S aggregate transitions on the fluorescent properties of anionic conjugated polyelectrolyte MPS-PPV with a larger molecular weight and cationic conjugated oligoelectrolyte DAB have been evaluated. Without BEO, SLE3S does not affect the fluorescent properties of MPS-PPV and only affects the fluorescent properties of DAB at a higher SLE3S concentration. With the addition of BEO, SLE3S and BEO form gemini-like surfactant (SLE3S)2-BEO. When the BEO/SLE3S molar ratio is fixed at 0.25, with increasing the BEO/SLE3S concentration, the BEO/SLE3S mixture forms large, loosely arranged aggregates and then transforms to closely packed spherical aggregates and finally to long thread-like micelles. The photoluminescence (PL) intensity of MPS-PPV varies with the morphologies of the BEO/SLE3S aggregates, while the PL intensity of DAB is almost independent of the aggregate morphologies. The results demonstrate that gemini-like surfactants formed through intermolecular interactions can effectively adjust the fluorescent properties of conjugated polyelectrolytes. PMID:25641198

  2. A Digital Variable-Angle Rolling-Ball Viscometer for Measurement of Viscosity, Density, and Bubble-Point Pressure of CO2 and Organic Liquid Mixtures

    NASA Astrophysics Data System (ADS)

    Sato, Yoshiyuki; Yoshioka, Hiroki; Aikawa, Shohei; Smith, Richard Lee

    2010-10-01

    A new apparatus was developed for measuring the viscosity, density, and bubble-point pressure of CO2 and organic liquid mixtures. The apparatus is based on the rolling-ball principle and consists of a computer-controlled stepper motor that rotates a high-pressure cell that is equipped with a sapphire window, a movable piston, and a position-sensing device. Design of the high-pressure cell was made such that compositions could be determined by mass. The viscosity was determined by sensing the speed of a rolling ball, and the density was determined by sensing the position of the piston with a linear-variable differential transformer. Bubble-point pressures were measured with the synthetic method. The viscosity and density of octane and decane were measured, and the average deviations of these properties compared with reliable literature values were 1.1 % and 0.15 %, respectively. The viscosity and density of CO2 + tetrahydrofuran system were measured at a temperature of 60 °C, a pressure of 10.2 MPa, and CO2 mole fractions up to 0.3. Bubble-point pressures for the CO2 + tetrahydrofuran system were in good agreement with literature data.

  3. Transfers of Colloidal Silica from Water into Organic Solvents of Intermediate Polarities

    Microsoft Academic Search

    Abdeslam Kasseh; Erlend Keh

    1998-01-01

    Dispersions of discrete metal-oxide submicroparticles in organic solvents of medium polarities are uneasy to generate and weakly documented. We address this topic along two general methods focusing on silica. Successive transfers of colloidal particles from water inton-propanol and then into 1,2-dichloroethane by azeotropic distillation yield a stable organosol. The particles are found to be propanol-coated by surface esterification to the

  4. A Thermodynamic Property Model for R-125/143a Mixtures Based on a New Cubic Equation of State

    NASA Astrophysics Data System (ADS)

    Zhang, Heng-Liang; Tada, Satoru; Waranabe, Koichi

    The binary mixture of two hydrofluorocarbons, R-125 and R-143a, behaves almost like an azeotrope and has been considered as a promising refrigerant to substitute R-502. In this paper, we present a thermodynamic property model for the R-125/143a system, which was developed on the basis of a new cubic equation of state proposed in our previous publications. The essential thermodynamic properties such as PVTx properties, vapor-liquid equilibrium, enthalpy, entropy, isobaric specific heat, and speed of sound are well represented simultaneously by the new model in the entire fluid-phase of theR-125/143a system including the pure components.The model is valid for any composition with thermodynamic consistency to cover a range broad enough for refrigeration engineering applications. A pressure-enthalpy diagram for the R-125/143a mixture with 50 mass% R-125 is also presented.

  5. Organic

    NSDL National Science Digital Library

    Quiz questions from the organic chemistry question bank provide students with an excellent opportunity to review key concepts.. The Organic topic focuses on the basics of organic chemistry that are taught in general chemistry.

  6. Markedly enhancing lipase-catalyzed synthesis of nucleoside drugs' ester by using a mixture system containing organic solvents and ionic liquid.

    PubMed

    Liu, Bo Kai; Wang, Na; Chen, Zhi Chun; Wu, Qi; Lin, Xian Fu

    2006-07-15

    Eightfold higher yields and three times faster reaction rates were achieved by means of using a mixture solvent system composed of 90% acetone and 10% [BMIM]BF4 in the lipase-catalyzed regioselective synthesis of polymerizable ester of nucleoside drugs. PMID:16682199

  7. Mixture design and multivariate analysis in mixture research.

    PubMed

    Eide, I; Johnsen, H G

    1998-12-01

    Mixture design has been used to identify possible interactions between mutagens in a mixture. In this paper the use of mixture design in multidimensional isobolographic studies is introduced. Mutagenicity of individual nitro-polycyclic aromatic hydrocarbons (PAH) was evaluated is an organic extract of diesel exhaust particles (DEPs). The particles were extracted with dichloromethane (DCM). After replacing DCM with dimethyl sulfoxide, the extract was spiked with three individual nitro-PAH: 1-nitropyrene, 2-nitrofluorene, and 1,8-dinitropyrene. The nitro-PAH were added separately and in various combinations to the extract to determine the effects of each variable and to identify possible interactions between the individual nitro-PAH and between the nitro-PAH and the extract. The composition of the mixtures was determined by mixture design (linear axial normal) with four variables (the DEP extract and the three nitro-PAH, giving 8 different mixtures plus a triplicate centerpoint, i.e., a total of 11. The design supports a model with linear and interaction (product) terms. Two different approaches were used: traditional mixture design within a well-defined range on the linear part of the dose-response curves and an isobolographic mixture design with equipotent doses of each variable. The mixtures were tested for mutagenicity in the Ames assay using the TA98 strain of Salmonella typhimurium. The data were analyzed with projections to latent structures (PLS). The three individual nitro-PAH and the DEP extract acted additively in the Ames test. The use of mixture design either within a well-defined range of the linear part on the dose-response curve or with equipotent doses saves experiments and reduces the possibility of false interaction terms in situations with dose additivity or response additivity. PMID:9860895

  8. Mixture design and multivariate analysis in mixture research.

    PubMed Central

    Eide, I; Johnsen, H G

    1998-01-01

    Mixture design has been used to identify possible interactions between mutagens in a mixture. In this paper the use of mixture design in multidimensional isobolographic studies is introduced. Mutagenicity of individual nitro-polycyclic aromatic hydrocarbons (PAH) was evaluated is an organic extract of diesel exhaust particles (DEPs). The particles were extracted with dichloromethane (DCM). After replacing DCM with dimethyl sulfoxide, the extract was spiked with three individual nitro-PAH: 1-nitropyrene, 2-nitrofluorene, and 1,8-dinitropyrene. The nitro-PAH were added separately and in various combinations to the extract to determine the effects of each variable and to identify possible interactions between the individual nitro-PAH and between the nitro-PAH and the extract. The composition of the mixtures was determined by mixture design (linear axial normal) with four variables (the DEP extract and the three nitro-PAH, giving 8 different mixtures plus a triplicate centerpoint, i.e., a total of 11. The design supports a model with linear and interaction (product) terms. Two different approaches were used: traditional mixture design within a well-defined range on the linear part of the dose-response curves and an isobolographic mixture design with equipotent doses of each variable. The mixtures were tested for mutagenicity in the Ames assay using the TA98 strain of Salmonella typhimurium. The data were analyzed with projections to latent structures (PLS). The three individual nitro-PAH and the DEP extract acted additively in the Ames test. The use of mixture design either within a well-defined range of the linear part on the dose-response curve or with equipotent doses saves experiments and reduces the possibility of false interaction terms in situations with dose additivity or response additivity. Images Figure 1 Figure 2 PMID:9860895

  9. Absence of lateral phase segregation in fatty acid-based catanionic mixtures.

    PubMed

    Michina, Youlia; Carrière, David; Charpentier, Thibault; Brito, Rodrigo; Marques, Eduardo F; Douliez, Jean-Paul; Zemb, Thomas

    2010-02-11

    Mixtures of ionic surfactants of opposite charge ("catanionic" mixtures) show strongly nonideal behaviors, for example, in terms of evolution of surface tension, critical micelle concentration, or morphology with respect to composition in each surfactant. In several catanionic systems, it has been proposed that the interaction between both surfactants is so strong that lateral phase segregation occurs within bilayers, with crystallites of preferential composition demixing from the excess of the other surfactant. Here, we investigate the temperature-composition phase diagram of the myristic acid/cetyltrimethylammonium mixtures. Combining microcalorimetry, X-ray diffusion, and solid-state deuterium NMR, we demonstrate that no separation is observed in the gel (L(beta)) state. The catanionic mixtures therefore behave like two-dimensional solid solutions with a negative azeotrope: the existence of a composition at which a maximum in melting temperature is observed does not imply the existence of a preferential crystal of this composition, but results from the preferential attraction between unlike amphiphilic molecules. Additionally, this study reveals the presence of a so-called intermediate phase, that is, a phase that shows dynamic properties intermediate between that of the L(beta) and the L(alpha) phases. PMID:20073496

  10. Generation of sub-ppb level vapor phase mixtures of biogenic volatile organic compounds from liquid phase standards and stepwise characterization of their volatilization properties by thermal desorption-gas chromatography-mass spectrometry.

    PubMed

    Iqbal, Mohammad Asif; Kim, Ki-Hyun

    2014-12-19

    In the analysis of biogenic volatile organic compounds (BVOCs) in ambient air, preparation of a sub-ppb level standard is an important factor. This task is very challenging as most BVOCs (e.g., monoterpenes) are highly volatile and reactive in nature. As a means to produce sub-ppb gaseous standards for BVOCs, we investigated the dynamic headspace (HS) extraction technique through which their vapors are generated from a liquid standard (mixture of 10 BVOCs: (1) ?-pinene, (2) ?-pinene, (3) 3-carene, (4) myrcene, (5) ?-phellandrene, (6) ?-terpinene, (7) R-limonene, (8) ?-terpinene, (9) p-cymene, and (10) Camphene) spiked into a chamber-style impinger. The quantification of BVOCs was made by collection on multiple-bed sorbent tubes (STs) and subsequent analysis by thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). Using this approach, sub-ppb level mixtures of gaseous BVOCs were generated at different sweep cycles. The mean concentrations of 10 BVOCs generated from the most stable conditions (i.e., in the third sweep cycle) varied in the range of 0.37±0.05 to 7.27±0.86ppb depending on the initial concentration of liquid standard spiked into the system. The reproducibility of the gaseous BVOCs generated as mixture standards, if expressed in terms of relative standard error using the concentration datasets acquired under stable conditions, ranged from 1.64 (?-phellandrene) to 9.67% (R-limonene). PMID:25464998

  11. In situ removal of arsenic from groundwater by using permeable reactive barriers of organic matter/limestone/zero-valent iron mixtures.

    PubMed

    Gibert, O; de Pablo, J; Cortina, J-L; Ayora, C

    2010-08-01

    In this study, two mixtures of municipal compost, limestone and, optionally, zero-valent iron were assessed in two column experiments on acid mine treatment. The effluent solution was systematically analysed throughout the experiment and precipitates from both columns were withdrawn for scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffractometry analysis and, from the column containing zero-valent iron, solid digestion and sequential extraction analysis. The results showed that waters were cleaned of arsenic, metals and acidity, but chemical and morphological analysis suggested that metal removal was not due predominantly to biogenic sulphide generation but to pH increase, i.e. metal (oxy)hydroxide and carbonate precipitation. Retained arsenic and metal removal were clearly associated to co-precipitation with and/or sorption on iron and aluminum (oxy)hydroxides. An improvement on the arsenic removal efficiency was achieved when the filling mixture contained zero-valent iron. Values of arsenic concentrations were then always below 10 microg/L. PMID:20387094

  12. IDENTIFICATION AND EXPERIMENTAL DATABASE FOR BINARY AND MULTICOMPONENT MIXTURES WITH POTENTIAL FOR INCREASING OVERALL CYCLE EFFICIENCY

    SciTech Connect

    Stephen M Bajorek; J. Schnelle

    2002-05-01

    This report describes an experimental investigation designed to identify binary and multicomponent mixture systems that may be for increasing the overall efficiency of a coal fired unit by extracting heat from flue gases. While ammonia-water mixtures have shown promise for increasing cycle efficiencies in a Kalina cycle, the costs and associated range of thermal conditions involved in a heat recovery system may prohibit its use in a relatively low temperature heat recovery system. This investigation considered commercially available non-azeotropic binary mixtures with a boiling range applicable to a flue gas initially at 477.6 K (400 F) and developed an experimental database of boiling heat transfer coefficients for those mixtures. In addition to their potential as working fluids for increasing cycle efficiency, cost, ease of handling, toxicity, and environmental concerns were considered in selection of the mixture systems to be examined experimentally. Based on this review, water-glycol systems were identified as good candidates. However, previous investigations of mixture boiling have focused on aqueous hydrocarbon mixtures, where water is the heaviest component. There have been few studies of water-glycol systems, and those that do exist have investigated boiling on plain surfaces only. In water-glycol systems, water is the light component, which makes these systems unique compared to those that have been previously examined. This report examines several water-glycol systems, and documents a database of experimental heat transfer coefficients for these systems. In addition, this investigation also examines the effect of an enhanced surface on pool boiling in water-glycol mixtures, by comparing boiling on a smooth surface to boiling on a Turbo IIIB. The experimental apparatus, test sections, and the experimental procedures are described. The mixture systems tested included water-propylene glycol, water-ethylene glycol, and water-diethylene glycol. All experimental data were obtained at atmospheric pressure with the test section oriented horizontally. The effect of subcooling in pool boiling of mixtures is another area that has received limited attention. Therefore, experimental data were obtained for the water-propylene glycol and water-ethylene glycol systems for subcoolings ranging from 0 to 30 C. The experimental data showed that boiling heat transfer coefficients were found to have significant degradation due to the mixture effect for each of the water-glycol systems examined. This result is consistent with previous studies which examined water-hydrocarbon mixtures with large boiling ranges. The Turbo BIII surface was found to significantly increase heat transfer in each mixture and pure component in comparison to that for the smooth surface.

  13. Solid-liquid phase equilibrium for binary Lennard-Jones mixtures

    NASA Astrophysics Data System (ADS)

    Hitchcock, Monica R.; Hall, Carol K.

    1999-06-01

    Solid-liquid phase diagrams are calculated for binary mixtures of Lennard-Jones spheres using Monte Carlo simulation and the Gibbs-Duhem integration technique of Kofke. We calculate solid-liquid phase diagrams for the model Lennard-Jones mixtures: argon-methane, krypton-methane, and argon-krypton, and compare our simulation results with experimental data and with Cottin and Monson's recent cell theory predictions. The Lennard-Jones model simulation results and the cell theory predictions show qualitative agreement with the experimental phase diagrams. One of the mixtures, argon-krypton, has a different phase diagram than its hard-sphere counterpart, suggesting that attractive interactions are an important consideration in determining solid-liquid phase behavior. We then systematically explore Lennard-Jones parameter space to investigate how solid-liquid phase diagrams change as a function of the Lennard-Jones diameter ratio, ?11/?22, and well-depth ratio, ?11/?22. This culminates in an estimate of the boundaries separating the regions of solid solution, azeotrope, and eutectic solid-liquid phase behavior in the space spanned by ?11/?22 and ?11/?22 for the case ?11/?22<0.85.

  14. Enhanced photocatalytic activity of TiO 2 nanofibers and their flexible composite films: Decomposition of organic dyes and efficient H 2 generation from ethanol-water mixtures

    Microsoft Academic Search

    Ming-Chung Wu; András Sápi; Anna Avila; Mária Szabó; Jussi Hiltunen; Mika Huuhtanen; Géza Tóth; Ákos Kukovecz; Zoltán Kónya; Riitta Keiski; Wei-Fang Su; Heli Jantunen; Krisztián Kordás

    2011-01-01

    TiO2 nanofibers decorated with Pt and Pd nanoparticles have been synthesized and studied in various photocatalytic processes.\\u000a Excellent photocatalytic behavior in the decomposition of organic dyes in water, degradation of organic stains on the surface\\u000a of flexible freestanding cellulose\\/catalyst composite films and in generation of hydrogen from ethanol using both suspended\\u000a and immobilized catalysts are demonstrated. The performance of the

  15. CHEMICAL MIXTURES: CONSEQUENCES FOR WATER QUALITY

    EPA Science Inventory

    Chemicals have the potential to occur as mixtures in sediment, as well as bioaccumulate in aquatic organisms, sometimes resulting in adverse toxicological effects. Presently, assessments of contaminated sediment are based upon single chemical toxicological studies with the assump...

  16. Amino Acid Synthesis from CO-N2 and CO-N2-H2 Gas Mixtures Via Complex Organic Compounds

    NASA Astrophysics Data System (ADS)

    Miyakawa, S.; Kobayashi, K.; Sawaoka, A. B.

    1999-01-01

    Reaction among hydrogen cyanide (HCN), formaldehyde (H2CO) and ammonia (NH3) are generally considered an important reaction in amino acid synthesis by electric discharge. Precursors of glycine and aspartic acid were, however, synthesized by adding water to metastable complex compounds produced by quenching a CO-N2 high-temperature plasma. In order to investigate effects of water remaining in an experimental vacuum chamber, optical emission spectroscopic and mass spectrometric measurements were conducted with CO-N2 and CO-N2-H2 gas mixtures. Although residual hydrogen atoms were detected in the CO-N2 experiment, the amount of them was much less than that in the CO-N2-H2 experiment

  17. organism

    Microsoft Academic Search

    RICHARD E. MICHOD

    The fitness of any evolutionary unit can be understood in terms of its two basic com- ponents: fecundity (reproduction) and viability (survival). Trade-offs between these fitness com- ponents drive the evolution of life-history traits in extant multicellular organisms. We argue that these trade-offs gain special significance during the transition from unicellular to multicellular life. In particular, the evolution of germ-soma

  18. Prediction of the phase behavior of acetonitrile and methanol with ab initio pair potentials. II. The mixture

    NASA Astrophysics Data System (ADS)

    Sum, Amadeu K.; Sandler, Stanley I.; Bukowski, Robert; Szalewicz, Krzysztof

    2002-05-01

    The comprehensive study of the ab initio pair potentials and prediction of properties for acetonitrile and methanol [J. Chem. Phys. 116, 7627 (2002), preceding paper] is extended to examine the vapor-liquid equilibria of their mixture. An ab initio pair interaction potential is developed for the acetonitrile-methanol interaction consistent with the pure component pair potentials using symmetry-adapted perturbation theory with a double zeta quality basis set including bond functions. Interaction energies were calculated for a large number of configurations to obtain a good representation of the potential energy surface, and employed to develop a site-site pair interaction potential. The ab initio pair potentials for the like and unlike interactions were then used in Gibbs ensemble Monte Carlo simulations to predict the phase behavior of the acetonitrile-methanol mixture. Simulations were performed to determine the phase boundary of the mixture, and although the predicted equilibrium concentrations are not in perfect agreement with experimental measurements, the predicted and measured phase boundaries are similar, including the occurrence of an azeotrope in close agreement with experiment. This prediction of mixture phase behavior is the first reported using ab initio potentials for both like and unlike interactions without the use of any combining rule.

  19. To the problem of self-assembly of mixtures of inorganic and organic phases under the sol-gel process conditions

    Microsoft Academic Search

    B. B. Troitskii; A. A. Babin; M. A. Lopatin; Yu. A. Mamaev; V. N. Denisova; M. A. Novikova; L. V. Khokhlova

    2008-01-01

    Under the sol-gel process conditions in the presence of citric, maleic, and phthalic acids and dioctyl phthalate spontaneous\\u000a microseparation of inorganic and organic phases with the formation of transparent in the visible spectral region film coatings\\u000a on glass is observed. The modified EISA method was proposed for the preparation of antireflecting coatings based on nanoporous\\u000a silica with the low refractive

  20. Mixtures Research at NIEHS: An Evolving Program

    PubMed Central

    Rider, Cynthia V; Carlin, Danielle J; DeVito, Micheal J; Thompson, Claudia L; Walker, Nigel J

    2014-01-01

    The National Institute of Environmental Health Sciences (NIEHS) has a rich history in evaluating the toxicity of mixtures. The types of mixtures assessed by the Division of the National Toxicology Program (DNTP) and the extramural community (through the Division of Extramural Research and Training (DERT)) have included a broad range of chemicals and toxicants, with each study having a unique set of questions and design considerations. Some examples of the types of mixtures studied include: groundwater contaminants, pesticides/fertilizers, dioxin-like chemicals (assessing the toxic equivalency approach), drug combinations, air pollution, metals, polycyclic aromatic hydrocarbons, technical mixtures (e.g. pentachlorophenol, flame retardants), and mixed entities (e.g. herbals, asbestos). These endeavors have provided excellent data on the toxicity of specific mixtures and have been informative to the human health risk assessment process in general (e.g. providing data on low dose exposures to environmental chemicals). However, the mixtures research effort at NIEHS, to date, has been driven by test article nominations to the DNTP or by investigator-initiated research through DERT. Recently, the NIEHS has embarked upon an effort to coordinate mixtures research across both intramural and extramural divisions in order to maximize mixtures research results. A path forward for NIEHS mixtures research will be based on feedback from a Request for Information (RFI) designed to gather up-to-date views on the knowledge gaps and roadblocks to evaluating mixtures and performing cumulative risk assessment, and a workshop organized to bring together mixtures experts from risk assessment, exposure science, biology, epidemiology, and statistics. The future of mixtures research at NIEHS will include projects from nominations to DNTP, studies by extramural investigators, and collaborations across government agencies that address high-priority questions in the field of mixtures research. PMID:23146757

  1. Optimal design and experimental validation of a simulated moving bed chromatography for continuous recovery of formic acid in a model mixture of three organic acids from Actinobacillus bacteria fermentation.

    PubMed

    Park, Chanhun; Nam, Hee-Geun; Lee, Ki Bong; Mun, Sungyong

    2014-10-24

    The economically-efficient separation of formic acid from acetic acid and succinic acid has been a key issue in the production of formic acid with the Actinobacillus bacteria fermentation. To address this issue, an optimal three-zone simulated moving bed (SMB) chromatography for continuous separation of formic acid from acetic acid and succinic acid was developed in this study. As a first step for this task, the adsorption isotherm and mass-transfer parameters of each organic acid on the qualified adsorbent (Amberchrom-CG300C) were determined through a series of multiple frontal experiments. The determined parameters were then used in optimizing the SMB process for the considered separation. During such optimization, the additional investigation for selecting a proper SMB port configuration, which could be more advantageous for attaining better process performances, was carried out between two possible configurations. It was found that if the properly selected port configuration was adopted in the SMB of interest, the throughout and the formic-acid product concentration could be increased by 82% and 181% respectively. Finally, the optimized SMB process based on the properly selected port configuration was tested experimentally using a self-assembled SMB unit with three zones. The SMB experimental results and the relevant computer simulation verified that the developed process in this study was successful in continuous recovery of formic acid from a ternary organic-acid mixture of interest with high throughput, high purity, high yield, and high product concentration. PMID:25240652

  2. Element, Mixture, Compound

    NSDL National Science Digital Library

    2014-09-18

    Students gain a better understanding of the different types of materials as pure substances and mixtures and learn to distinguish between homogeneous and heterogeneous mixtures by discussing an assortment of example materials they use and encounter in their daily lives.

  3. Separation of methanol from methylesters by vapour permeation: experiences of industrial applications

    Microsoft Academic Search

    Eva Maus; Hartmut E. A. Brüschke

    2002-01-01

    Separation of water from its mixtures with organic liquids, especially from those with which it forms azeotropes by means of pervaporation and vapour permeation. has matured during the past 10 years to a state-of-the-art technology. The processes are applied in industrial plants worldwide for the dehydration of binary mixtures of light alcohols such as ethanol or isopropanol, esters such as

  4. New model that describes adsorption of laterally interacting gas mixtures on random heterogeneous surfaces. 2: Correlation of complex binary and prediction of multicomponent adsorption equilibria

    SciTech Connect

    Al-Muhtaseb, S.A.; Ritter, J.A.

    1999-10-26

    The model developed in part 1 of this series for correlating single component and rather ideal binary adsorption equilibria demonstrated a remarkable ability for correlating complex binary adsorption equilibria, including adsorption azeotropes and sigmoidal-shaped x-y diagrams, using a single binary fitting parameter. This model was also extended successfully for predicting multicomponent adsorption equilibria on a heterogeneous adsorbent surface with a uniform distribution of Henry's law constant using single component adsorption isotherm parameters, along with one binary fitting parameter from each of the binary pairs in the multicomponent mixture. Overall, the results from this new model generally showed a marked improvement in the correlation of binary and prediction of multicomponent adsorption equilibria compared to that obtained with the multicomponent Langmuir model, which used only single component isotherm parameters, and compared to that obtained with two-dimensional fluid and loading ratio correlation models that also utilized binary fitting parameters.

  5. Mixture or Solution?

    NSDL National Science Digital Library

    steve burns

    2011-10-09

    Textbook definition: "Mixtures are formed simply by blending two or more substances together in some random proportion without chemically changing the individual substances in the mixture." Mixtures can then be broken down into homogeneous and heterogeneous. A homogeneous mixture is called a solution: salt or sugar and water, air (solution of gases). These have a constant composition throughout the solution. A heterogeneous mixture would be: salt with sugar (no water), water with gasoline or oil, salt with sand. These have areas with differing compositions (you could usually see the separation of the two things).

  6. Correlation of refrigerant mass flow rate through adiabatic capillary tubes using mixture refrigerant carbondioxide and ethane for low temperature applications

    NASA Astrophysics Data System (ADS)

    Nasruddin, Syaka, Darwin R. B.; Alhamid, M. Idrus

    2012-06-01

    Various binary mixtures of carbon dioxide and hydrocarbons, especially propane or ethane, as alternative natural refrigerants to Chlorofluorocarbons (CFCs) or Hydro fluorocarbons (HFCs) are presented in this paper. Their environmental performance is friendly, with an ozone depletion potential (ODP) of zero and Global-warming potential (GWP) smaller than 20. The capillary tube performance for the alternative refrigerant HFC HCand mixed refrigerants have been widely studied. However, studies that discuss the performance of the capillary tube to a mixture of natural refrigerants, in particular a mixture of azeotrope carbon dioxide and ethane is still undeveloped. A method of empirical correlation to determine the mass flow rate and pipe length has an important role in the design of the capillary tube for industrial refrigeration. Based on the variables that effect the rate of mass flow of refrigerant in the capillary tube, the Buckingham Pi theorem formulated eight non-dimensional parameters to be developed into an empirical equations correlation. Furthermore, non-linear regression analysis used to determine the co-efficiency and exponent of this empirical correlation based on experimental verification of the results database.

  7. Carburetor mixture control apparatus

    SciTech Connect

    Dalke, A.E.

    1983-11-29

    A mixture control device is disclosed for automatically controlling the air to fuel mixture of a conventional carburetor involving a plurality of sloped radial vanes circumferentially located within the annulus formed by the booster venturi and the venturi tube. By inducing significant centrifugal motion in the air passing outside the booster venturi the problems associated with fuel to air mixture changes associated with changes in elevation and changes in seasonal temperatures are alleviated.

  8. Messin' with Mixtures

    NSDL National Science Digital Library

    2014-09-18

    In this activity, students investigate the properties of a heterogeneous mixture, trail mix, as if it were a contaminated soil sample near a construction site. This activity shows students that heterogeneous mixtures can be separated by physical means, and that when separated, all the parts will equal the whole.

  9. Evaluation of the stability of a mixture of volatile organic compounds on sorbents for the determination of emissions from indoor materials and products using thermal desorption/gas chromatography/mass spectrometry.

    PubMed

    Brown, Veronica M; Crump, Derrick R; Plant, Neil T; Pengelly, Ian

    2014-07-11

    The standard method for the determination of volatile organic compounds (VOCs) in indoor and test chamber air (ISO 16000-6:2011) specifies sampling onto the sorbent Tenax TA followed by analysis using thermal desorption/gas chromatography/mass spectrometry (TD/GC/MS). The informative Annex D to the standard suggests the use of multi-sorbent samplers to extend the volatility range of compounds which can be determined. The aim of this study was to investigate the storage performance of Tenax TA and two multi-sorbent tubes loaded with a mixture of nine VOCs of relevance for material emissions testing. The sorbent combinations tested were quartz wool/Tenax TA/Carbograph™ 5TD and quartz wool/Tenax TA/Carbopack™ X. A range of loading levels, loading conditions (humidities and air volume), storage times (1-4 weeks) and storage conditions (refrigerated and ambient) were investigated. Longer term storage trials (up to 1 year) were conducted with Tenax TA tubes to evaluate the stability of tubes used for proficiency testing (PT) of material emissions analyses. The storage performance of the multi-sorbent tubes tested was found to be equal to that for Tenax TA, with recoveries after 4 weeks storage of within about 10% of the amounts loaded. No consistent differences in recoveries were found for the different loading or storage conditions. The longer term storage trials also showed good recovery for these compounds, although two other compounds, hexanal and BHT, were found to be unstable when stored on Tenax TA. The results of this study provide confidence in the stability of nine analytes for up to 4 weeks on two multi-sorbent tubes for material emissions testing and the same compounds loaded on Tenax TA sorbent for a recently introduced PT scheme for material emissions testing. PMID:24877978

  10. Home Connections: Demystifying Mixtures

    NSDL National Science Digital Library

    Kathleen Damonte

    2003-10-01

    The subject of chemistry makes most people think of an elaborate laboratory, but investigating chemistry concepts does not require expensive equipment or chemicals. You can perform some of the same tests scientists do using materials in your home. One topic chemists study is mixtures and the substances that make them up. In this activity you will use a process called chromatography to find out what makes up a mixture you use often: black ink.

  11. Separating a Mixture

    NSDL National Science Digital Library

    2012-07-12

    This activity was designed for blind learners, but all types of learners can explore means of physically separating a mixture using dissolving, filtration, and evaporation. Separating a sand/salt mixture is a common experiment in physical science class that requires almost no adaptation for learners with visual impairments. This activity also provides experience in popular laboratory techniques of dissolving, filtration, and evaporation. In this activity, the learner will use filters and funnels to separate sand and salt.

  12. New developments in mixture toxicity parameters

    SciTech Connect

    Hermens, J.; Loon, W. van; Verhaar, H.; Leeuwen, K. van [Utrecht Univ. (Netherlands). Research Inst. of Toxicology

    1995-12-31

    The potential toxicological effects of complex organic mixtures in water are usually evaluated based on standard bioassays, chemical analyses or chemical assays such as Extractable Organic Halogen (EOX) content. There is a need for additional chemical and biochemical techniques which supply information on concentrations of chemicals and which can directly be translated into toxicological information. A major class of chemical pollutants in the environment consist out of baseline toxicity chemicals which act by narcosis. The major characteristic of effects (survival or growth inhibition) of mixtures of chemicals with baseline toxicity is that they are completely additive and occur at a fixed body burden. A parameter was recently developed which simulates bioaccumulation and which measures the total baseline toxicity of organic mixtures in water. The parameter is based on a simulation of bioconcentration and measurement of total molar concentrations via vapor pressure osmometry on a hydrophobic phase. In this presentation the results of the application of this procedure to effluents and surface water are presented. Moreover, the use of GC-MS as a technique for measuring total molar concentrations is presented. The results for total molar concentrations measured via vapor pressure osmometry and GS-MS are compared and both techniques essentially give the same answer. The application of the new approach in evaluating the effects of complex mixtures is discussed in the light of future developments.

  13. Organic electrolyte cell

    SciTech Connect

    Fujii, T.; Iijima, T.

    1986-08-26

    An organic electrolyte cell is described, which comprises a cathode using as an active material a mixture of copper oxide and chalcopyrite, an anode using as an active material lithium or a lithium base alloy, and an organic electrolyte comprising a salt dissolved in an organic solvent.

  14. POTENTIAL EMISSIONS OF HAZARDOUS ORGANIC COMPOUNDS FROM SEWAGE SLUDGE INCINERATION

    EPA Science Inventory

    Laboratory thermal decomposition studies were undertaken to evaluate potential organic emissions from sewage sludge incinerators. Precisely controlled thermal decomposition experiments were conducted on sludge spiked with mixtures of hazardous organic compounds, on the mixtures o...

  15. Mixtures and Solutions

    NSDL National Science Digital Library

    Perkins School for the Blind

    2012-06-26

    This activity was designed for blind learners, but all types of learners can use it to investigate heterogeneous and homogeneous mixtures and solutions, identify the differences, and explore the concepts of concentration and dilution. Learners with visual impairments as well as sighted learners will create both types of mixtures and solutions. Depending on the experience of the learners and the time available, this activity can be presented as three different activities or done sequentially. Materials can be edible, such as trail mix and powered drink mix, or nonedible, such as buttons.

  16. Structure and phase equilibria of mixtures of the complex salt hexadecyltrimethylammonium polymethacrylate, water and different oils

    Microsoft Academic Search

    Juliana Silva Bernardes; Watson Loh

    2008-01-01

    This work reports on phase diagrams for mixtures of a complex salt formed by a cationic surfactant and an oppositely charged polyelectrolyte, hexadecyltrimethylammonium polymethacrylate, in binary mixtures with water and in ternary mixtures containing water and organic solvents of different polarity (‘oils’): decanol, octanol, p-xylene and cyclohexane. The liquid crystalline structures formed were identified by small angle X-ray scattering measurements,

  17. Z .Fluid Phase Equilibria 150151 1998 151159 Thermal diffusion in alkane binary mixtures

    E-print Network

    Dysthe, Dag Kristian

    Z .Fluid Phase Equilibria 150­151 1998 151­159 Thermal diffusion in alkane binary mixtures the thermal conductivity and the thermal diffusion coefficient a in a methane-n-decane binary mixture in the in organic binary mixtures in order to give `experimental-like' data for the thermal diffusion factor

  18. MIXTURES FEASIBILITY STUDY

    EPA Science Inventory

    A number of studies have been conducted to address questions concerning the toxicity of "real world" mixtures of DBPs. These studies, which used either concentrates of drinking water or humic acid preparations treated with various disinfectants, were largely negative and had a nu...

  19. Mass spectrometer mixture calibrations

    Microsoft Academic Search

    Hicks

    1986-01-01

    Mass spectrometric analyses of hydrogen isotope mixtures can be difficult to make for a number of reasons. The most difficult problem is the possibility of confronting extremely great and extremely small relative mass differences in the same analysis. Commercial mass spectrometers are now available that can overcome these problems. The analytical capabilities and limitations of these instruments will be discussed.

  20. Pharmaceutical applications for catanionic mixtures.

    PubMed

    Bramer, Tobias; Dew, Noel; Edsman, Katarina

    2007-10-01

    Mixtures of oppositely charged surfactants, so called catanionic mixtures, are a growing area of research. These mixtures have been shown to form several different types of surfactant aggregates, such as micelles of various forms and sizes, and lamellar structures, such as vesicles. In this review, a short introduction to the field of catanionic mixtures is presented and the pharmaceutical possibilities offered by such mixtures are reviewed. There are several interesting ideas on how to apply catanionic mixtures to improve the delivery of, for example, drug compounds and DNA, or for HIV treatment. PMID:17910806

  1. EVALUATION OF THE JOINT TOXIC ACTION OF MIXTURES OF HALOACETIC ACIDS CONSTRUCTED USING ENVIRONMENTAL CONCENTRATION/EXPOSURE DATA

    EPA Science Inventory

    Disinfection byproducts (DBPs) are formed by reactions between chemicals used to disinfect water and organic compounds present in source water. The composition of DBP mixtures varies based on a number of factors, including treatment scenario, with different DBP mixtures contain...

  2. Genotoxicity of complex chemical mixtures

    E-print Network

    Phillips, Tracie Denise

    2009-05-15

    , distribution, metabolism or excretion of the components of a complex mixture. The research conducted for this dissertation has coupled chemical fractionation with in vitro and in vivo bioassays to assess the potential carcinogenic risk of complex mixtures. A...

  3. Hydrodynamic gas mixture separation

    SciTech Connect

    Stolyarov, A.A.

    1982-02-10

    The separation of gas mixtures is the basis of many chemical, petrochemical, and gas processes. Classical separation methods (absorption, adsorption, condensation, and freezing) require cumbersome and complex equipment. No adequate solution is provided by the cheapening and simplification of gas-processing apparatus and separation methods by hydration and diffusion. For example, an apparatus for extracting helium from natural gas by diffusion has a throughput of gas containing 0.45% helium of 117,000 m/sup 3//h and in the first stage has teflon membranes working at a pressure difference of 63.3x10/sup 5/ Pa of area 79,000 m/sup 2/, and the specific cost of the apparatus was 8500 dollars per m/sup 3//h of helium. Therefore, vigorous studies are being conducted on new ways of efficient separation of gas mixtures that are cheaper and simpler. Here we consider a novel method of physically essentially reversible separation of gas mixtures, which involves some features of single-phase supersonic flows.

  4. Theoretical interpretation of the effect of mixture composition on separation of liquids in polymers

    Microsoft Academic Search

    Morton Fels; Robert Y. M. Huang

    1971-01-01

    A theoretical interpretation for the permeation of binary organic liquid mixtures through polymer films is developed. The model is based on an extension of the free-volume theory for diffusion of organic substances in polymers and takes into account the effect of one component of the mixture on the diffusion of the other component. The calculated permeabilities are in reasonable agreement

  5. Thermodynamic study of (anthracene + benzo[a]pyrene) solid mixtures

    PubMed Central

    Rice, James W.; Suuberg, Eric M.

    2010-01-01

    To characterize better the thermodynamic behavior of a binary polycyclic aromatic hydrocarbon mixture, thermochemical and vapor pressure experiments were used to examine the phase behavior of the {anthracene (1) + benzo[a]pyrene (2)} system. A solid-liquid phase diagram was mapped for the mixture. A eutectic point occurs at x1 = 0.26. The eutectic mixture is an amorphous solid that lacks organized crystal structure and melts between T = (414 and 420) K. For mixtures that contain 0.10 < x1 < 0.90, the enthalpy of fusion is dominated by that of the eutectic. Solid-vapor equilibrium studies show that mixtures of anthracene and benzo[a]pyrene at x1 < 0.10 sublime at the vapor pressure of pure benzo[a]pyrene. These results suggest that the solid-vapor equilibrium of benzo[a]pyrene is not significantly influenced by moderate levels of anthracene in the crystal structure. PMID:20814451

  6. Oxidative particle mixtures for groundwater treatment

    DOEpatents

    Siegrist, Robert L. (Boulder, CO); Murdoch, Lawrence C. (Clemson, SC)

    2000-01-01

    The invention is a method and a composition of a mixture for degradation and immobilization of contaminants in soil and groundwater. The oxidative particle mixture and method includes providing a material having a minimal volume of free water, mixing at least one inorganic oxidative chemical in a granular form with a carrier fluid containing a fine grained inorganic hydrophilic compound and injecting the resulting mixture into the subsurface. The granular form of the inorganic oxidative chemical dissolves within the areas of injection, and the oxidative ions move by diffusion and/or advection, therefore extending the treatment zone over a wider area than the injection area. The organic contaminants in the soil and groundwater are degraded by the oxidative ions, which form solid byproducts that can sorb significant amounts of inorganic contaminants, metals, and radionuclides for in situ treatment and immobilization of contaminants. The method and composition of the oxidative particle mixture for long-term treatment and immobilization of contaminants in soil and groundwater provides for a reduction in toxicity of contaminants in a subsurface area of contamination without the need for continued injection of treatment material, or for movement of the contaminants, or without the need for continuous pumping of groundwater through the treatment zone, or removal of groundwater from the subsurface area of contamination.

  7. Organic waste converter

    Microsoft Academic Search

    Schlichting

    1981-01-01

    An airtight chamber insulated with an anti-corrosive coating allows the control of the heat and moisture content of organic wastes for rapid aerobic decomposition by naturally occurring thermal bacteria. Air is drawn into the chamber, over and through the organic waste and carbonaceous filler materials and is exhausted through an air scrubber. Agitation of the waste mixture is by means

  8. Toxicological approaches to complex mixtures.

    PubMed Central

    Mauderly, J L

    1993-01-01

    This paper reviews the role of toxicological studies in understanding the health effects of environmental exposures to mixtures. The approach taken is to review mixtures that have received the greatest emphasis from toxicology; major mixtures research programs; the toxicologist's view of mixtures and approaches to their study; and the complementary roles of toxicological, clinical, and epidemiological studies. Studies of tobacco smoke, engine exhaust, combustion products, and air pollutants comprise most of the past research on mixtures. Because of their great experimental control over subjects, exposures, and endpoints, toxicologists tend to consider a wider range of toxic interactions among mixture components and sequential exposures than is practical for human studies. The three fundamental experimental approaches used by toxicologists are integrative (studying the mixture as a whole), dissective (dissecting a mixture to determine causative constituents), and synthetic (studying interactions between agents in simple combinations). Toxicology provides information on potential hazards, mechanisms by which mixture constituents interact to cause effects, and exposure dose-effect relationships; but extrapolation from laboratory data to quantitative human health risks is problematic. Toxicological, clinical, and epidemiological approaches are complementary but are seldom coordinated. Fostering synergistic interactions among the disciplines in studying the risks from mixtures could be advantageous. PMID:7515806

  9. Continuous dielectrophoretic separation of cell mixtures.

    PubMed

    Pohl, H A; Kaler, K

    1979-03-01

    Use of stream-centered dielectrophoresis (1-4) produced continuous separations on three cell mixtures (1) Chorella vulgaris with Netrium digitus, (2) Ankistrodesmus falcatus with Staurastrum gracile, and (3) Saccharomyces cerevisiae with Netrium digitus. Maximal separations were obtained for these mixtures of live cells at 100 kHz, 600 kHz, and 2.0 MHz, respectively. The technique was restricted to a frequency range of 0.01-32 MHz, and to suspensions of low conductivity in which microorganisms such as these algae and yeast are tolerant. Extension, however, to cellular organisms requiring higher osmolarity is readily feasible through the use of nonionic solutes such as sucrose, mannose, glycine, etc. PMID:95165

  10. Separation of a Five-Component Mixture in the Microscale Laboratory.

    ERIC Educational Resources Information Center

    O'Hara-Mays, Ellen P.; Yuen, George U.

    1989-01-01

    Described is a microscale organic chemistry laboratory which involves the separation and purification of a mixture consisting of a strong organic acid, a weak organic acid, an organic base, and two neutral compounds. Reinforced are the basic principles of acid/base chemistry and the physical properties of the associated functional groups. (CW)

  11. Water-enhanced solvation of organic solutes in ketone and ester solvents

    SciTech Connect

    Lee, J.H.; Brunt, V. van; King, C.J. (Univ. of California, Berkeley, CA (United States). Dept. of Chemical Engineering Lawrence Berkeley Lab., CA (United States))

    1994-05-01

    Previous research has shown that the solubilities of dicarboxylic acids in certain electron-donor solvents are substantially increased in the presence of water. Information on solubilities, liquid-liquid equilibria and maximum-boiling ternary azeotropes was screened so as to identify other systems where codissolved water appears to enhance solvation of organic solutes in solvents. Several carboxylic acids, an alcohol, diols, and phenols were selected for examination as solutes in ketone and ester solvents. Effects of water upon solute solubilities and volatilities were measured. Results showed that water-enhanced solvation is greatest for carboxylic acids. Solute activity coefficients decreased by factors of 2--3, 6--8, and 7--10 due to the presence of water for mono-, di and tricarboxylic acids, respectively. Activity coefficients decreased by a factor of about 1.5 for ethanol and 1,2-propanediol as solutes. Water-enhanced solvation of phenols is small, when existent.

  12. Image Denoising Using Mixtures of Projected Gaussian Scale Mixtures

    E-print Network

    Pizurica, Aleksandra

    and have heavy tails [2], [3]. In literature, many wavelet-based image denoising methods have arisen1 Image Denoising Using Mixtures of Projected Gaussian Scale Mixtures Bart Goossens, Aleksandra, both visually and in PSNR compared to the current wavelet-based state-of-the-art denoising methods

  13. COMPLEX MIXTURES AND GROUNDWATER QUALITY

    EPA Science Inventory

    Experience has shown that many soil and ground-water contamination problems involve complex mixtures of chemicals. his manuscript identifies and discusses, in a generic sense, some of the important processes which must be considered when dealing with complex mixtures in the subsu...

  14. RISK ASSESSMENT OF COMPLEX MIXTURES

    EPA Science Inventory

    Quantitative carcinogenic assessment of complex mixtures is complicated by the variability of the mixtures. Different samples of effluents from the same source may vary in their carcinogenic potency. A multiplicative effect could be produced by the action of different fractions o...

  15. Development of more efficacious Tc-99m organ imaging agents for use in nuclear medicine by analytical characterization of radiopharmaceutical mixtures. Progress report, May 1, 1980-April 30, 1981. [/sup 99m/Tc(NaBH/sub 4/)HEDP

    SciTech Connect

    Heineman, W. R.; Deutsch, E. A.

    1980-12-01

    High performance liquid chromatography (HPLC) was used to efficiently separate and detect the individual components in a radiopharmaceutical mixture. A procedure for separating Tc(NaBH/sub 4/)HEDP radiopharmaceutical analogues by anion exchange HPLC with uv-visible and ..gamma.. detection was developed. Such preparations consist of as many as 7 Tc-containing components, the relative quantities of which are highly dependent on the conditions during preparation and subsequent handling. The in vivo distributions of 3 of the isolated Tc-HEDP species were evaluated as skeletal imaging agents in normal rats. The chromatographically separated Tc-HEDP components exhibit distinctly different biodistributions which are related to the chromatographic characteristics of the individual components. These same Tc-HEDP components were evaluated for uptake in myocardial infarcts using the isoproterenol-induced necrosis model in the rat. The relative uptake of the various components in the infarcted heart parallels the skeletal uptake. An optically transparent thin layer electrochemical flow cell was developed and characterized. This cell enables optical and electrochemical measurements to be made simultaneously on individual Tc-HEDP complexes as they elute from the HPLC. These results demonstrate the potential presence of numerous technetium complexes in radiopharmaceuticals and the efficacy of HPLC as a mode of separation and detection of these complexes. One particular component in the Tc(NaBH/sub 4/)HEDP radiopharmaceutical analogue is more effective than the others for both skeletal and myocardial infarct uptake. This is strongly suggestive that a more efficacious radiopharmaceutical would result from the administration of this single component.

  16. Method and compositions for the degradation of tributyl phosphate in chemical waste mixtures

    DOEpatents

    Stoner, Daphne L. (Idaho Falls, ID); Tien, Albert J. (Zurich, CH)

    1995-01-01

    A method and process for the degradation of tributyl phosphate in an organic waste mixture and a biologically pure, novel bacteria culture for accomplishing the same. A newly-discovered bacteria (a strain of Acinetobacter sp. ATCC 55587) is provided which is combined in a reactor vessel with a liquid waste mixture containing tributyl phosphate and one or more organic waste compounds capable of functioning as growth substrates for the bacteria. The bacteria is thereafter allowed to incubate within the waste mixture. As a result, the tributyl phosphate and organic compounds within the waste mixture are metabolized (degraded) by the bacteria, thereby eliminating such materials which are environmentally hazardous. In addition, the bacteria is capable of degrading waste mixtures containing high quantities of tributyl phosphate (e.g. up to about 1.0% by weight tributyl phosphate).

  17. Method and compositions for the degradation of tributyl phosphate in chemical waste mixtures

    DOEpatents

    Stoner, D.L.; Tien, A.J.

    1995-09-26

    A method and process are disclosed for the degradation of tributyl phosphate in an organic waste mixture and a biologically pure, novel bacteria culture for accomplishing the same. A newly-discovered bacteria (a strain of Acinetobacter sp. ATCC 55587) is provided which is combined in a reactor vessel with a liquid waste mixture containing tributyl phosphate and one or more organic waste compounds capable of functioning as growth substrates for the bacteria. The bacteria is thereafter allowed to incubate within the waste mixture. As a result, the tributyl phosphate and organic compounds within the waste mixture are metabolized (degraded) by the bacteria, thereby eliminating such materials which are environmentally hazardous. In addition, the bacteria is capable of degrading waste mixtures containing high quantities of tributyl phosphate (e.g. up to about 1.0% by weight tributyl phosphate). 6 figs.

  18. Liquefaction process for a hydrothermally treated waste mixture containing plastics

    Microsoft Academic Search

    Motoyuki Sugano; Akihiro Komatsu; Masanori Yamamoto; Mika Kumagai; Takayuki Shimizu; Katsumi Hirano; Kiyoshi Mashimo

    2009-01-01

    Most landfilled plastic waste is a mixture or is in the form of composites with incombustible wastes such as glass, metals,\\u000a and ceramics. After hydrothermal treatment, including a steam-explosion process, the separation of mixed waste (MW) into organic\\u000a and inorganic substances becomes easy. However, the effect of hydrothermal pretreatment on the subsequent liquefaction of\\u000a organic substances from MW is not

  19. Prediction of Asphalt Mixture Compactability from Mixture, Asphalt, and Aggregate Properties 

    E-print Network

    Muras, Andrew J.

    2010-07-14

    analysis of the correlation between HMA mixture properties and laboratory compaction parameters for the purpose of predicting compactability. Mixture property data were measured for a variety of mixtures; these mixtures were compacted in the laboratory...

  20. An engineered mutant, L307V of phenylalanine dehydrogenase from Bacillus sphaericus: high activity and stability in organic-aqueous solvent mixtures and utility for synthesis of non-natural l-amino acids

    Microsoft Academic Search

    Sihong Chen; Paul C. Engel

    2007-01-01

    A study of an engineered phenylalanine dehydrogenase (PheDH) mutant, L307V, from Bacillus sphaericus, catalysing the oxidation of l-phenylalanine (Phe) and five non-natural p-substituted derivatives (4-F\\/Cl\\/CH3\\/OCH3\\/NO2-l-Phe) in water-miscible organic solvents, methanol, ethanol and acetonitrile, is reported. Results showed that the enzyme still had high activity with 0.2mM 4-CH3\\/OCH3\\/NO2-l-Phe in 10% methanol. The kinetic parameters of the enzyme were determined with three

  1. Isobaric vapor–liquid equilibrium for binary and ternary mixtures of ethanol+2-methyl-2-propanol and 2-methylpentane+ethanol+2-methyl-2-propanol

    Microsoft Academic Search

    Antonio Aucejo; Sonia Loras; Rosa Muñoz; Luis Miguel Ordoñez

    1999-01-01

    Consistent vapor–liquid equilibrium data for the binary and ternary systems ethanol+2-methyl-2-propanol (TBA) and 2-methylpentane+ethanol+TBA are reported at 101.3 kPa. In the binary system, the results indicate a negative deviation from ideality and no azeotrope is present. The ternary system shows negative and positive deviations from ideality, does not present azeotrope, and is well predicted from binary data. The activity coefficients

  2. Simplex-centroid mixture formulation for optimised composting of kitchen waste

    Microsoft Academic Search

    N. Abdullah; N. L. Chin

    2010-01-01

    Composting is a good recycling method to fully utilise all the organic wastes present in kitchen waste due to its high nutritious matter within the waste. In this present study, the optimised mixture proportions of kitchen waste containing vegetable scraps (V), fish processing waste (F) and newspaper (N) or onion peels (O) were determined by applying the simplex-centroid mixture design

  3. Toxicity of a Complex Mixture of Atmospherically Transported Pesticides to Ceriodaphnia Dubia

    Microsoft Academic Search

    Tara K. George; Don Waite; Karsten Liber; Jim Sproull

    2003-01-01

    The presence of several anthropogenic chemicals has been documented in the atmosphere of the Canadian prairies. The deposition of these chemicals as a mixture is of importancesince little is known of the combined effects of these chemicalson aquatic organisms. This study was designed to evaluate theacute and chronic toxicity of a complex mixture of nineatmospherically transported pesticides to Ceriodaphniadubia. The

  4. An analytical evaluation of flammability limits of gaseous mixtures of combustible–oxidizer–diluent

    Microsoft Academic Search

    Yu. N. Shebeko; W. Fan; I. A. Bolodian; V. Yu. Navzenya

    2002-01-01

    This paper is aimed at the creation of new methods for the analytical evaluation of flammability limits of ternary gaseous mixtures of combustible–oxidizer–diluent. The physical nature of flammability limits is considered using some peculiarities of the chemical kinetics of combustion of gaseous organic substances in air. New features of lower flammability limits and compositions of mixtures near peak points of

  5. Experimental Investigation on High-pressure, High-temperature Viscosity of Gas Mixtures 

    E-print Network

    Davani, Ehsan

    2012-02-14

    of pure hydrocarbon gas, such as methane, ethane, propane and n-butane, and provided an organized database. Lee also used a 15 capillary tube viscometer and measured the viscosity of hydrocarbon gas mixtures (methane/propane, methane/butane...

  6. PREDICTION OF THE SOLUBILITY OF HYDROPHOBIC COMPOUNDS IN NONIDEAL SOLVENT MIXTURES

    EPA Science Inventory

    The solubility of hydrophobic organic chemicals (HOCs) in partially-miscible solvent mixtures was investigated. In agreement with previous findings, it was observed that there is a limited domain in which nonideality effects are important; appreciable concentrations of partially ...

  7. PREDICTION OF THE SOLUBILITY OF HYDROPHOBIC COMPOUNDS IN NONIDEAL SOLVENT MIXTURES

    EPA Science Inventory

    The solubility of hydrophobic organic chemicals (HOCs) in partially-miscible solvent mixtures was investigated. In agreement with previous findings, it was observed that there is a limited domain in which nonideality effects are important; appreciable concentrations of partially-...

  8. Gas adsorption and gas mixture separations using mixed-ligand MOF material

    DOEpatents

    Hupp, Joseph T. (Northfield, IL); Mulfort, Karen L. (Chicago, IL); Snurr, Randall Q. (Evanston, IL); Bae, Youn-Sang (Evanston, IL)

    2011-01-04

    A method of separating a mixture of carbon dioxiode and hydrocarbon gas using a mixed-ligand, metal-organic framework (MOF) material having metal ions coordinated to carboxylate ligands and pyridyl ligands.

  9. Seeking solutions to chemical mixtures challenges in public health.

    PubMed

    Mumtaz, M M; Rosa, C T De; Cibulas, W; Falk, H

    2004-11-01

    The Agency for Toxic Substances and Disease Registry (ATSDR) identifies people near hazardous waste sites who are at potential health risk because of their exposure to environmental chemicals. Nearly, 2000 chemicals have been associated with such sites. Residents of U.S. communities are potentially exposed to hazardous substances through air, soil, drinking water, and food. The agency has determined that more than 73 million people live within a 4-mile radius of waste sites. More than 14 million Americans live within 1 mile of a National Priorities List site, of which 11% are 7 years of age or younger, 12% are 64 years of age or older, 24% are women of childbearing age, and 25% are minorities. The lack of adequate environmental sampling and information on human exposures often restricts ATSDR's evaluation and assessment activities. Assessing human exposure with its attendant health risks and outcomes is complex because many populations have a wide range of reported illnesses, and generally exposures are to mixtures of chemicals. This prompted ATSDR to consider mixtures issues more in depth and to establish a formal mixtures assessment and research program in 1994. In this paper, we present an overview of the agency activities, the genesis, legislative mandates, and pertinence of the mixtures program including applied research and the development of methods for evaluating the impact of multiple-chemical exposure. On the basis of 20-year experience of evaluating and researching environmental chemical mixtures at waste sites, ATSDR convened the International Conference on Chemical Mixtures (ICCM) in 2002. The conference was supported by several federal agencies and scientific organizations and attended by international and national experts. The conference addressed broad topics such as prevalence of exposures to chemical mixtures, importance of interactions at environmentally relevant levels, validity of assuming additivity (dose or response) as default for mixtures assessment, and promising avenues in the three broad areas, viz., research, assessment, and computational tools. PMID:21782735

  10. Reconciling scientific approaches for organic farming research. Part I. Reflection on research methods in organic grassland and animal production at the Louis Bolk Institute, The Netherlands. Part II. Effects of manure types and white clover (Trifolium repens) cultivars on the productivity of grass-clover mixtures on a humid sandy soil

    Microsoft Academic Search

    T. Baars

    2002-01-01

    Part I<\\/strong> : Reflection on research methods in organic grassland and animal production at the Louis Bolk Institute, The NetherlandsKey words: organic agriculture, anthroposophy, methodology, research strategy, experiential science, multidisciplinary science, Goethean scienceThis dissertation focuses on the research question: what is peculiar to agricultural research when its purpose is to support the conscious development of organic agriculture? What approaches, designs

  11. Absorption of sound in liquids and liquid mixtures 

    E-print Network

    Musa, Raiq S

    1955-01-01

    with Burton's results and are nearly twice the 1947 Pinkerton values. Bette tested Hall's theory on ethyl alcohol and arrived at a value of 6 a/f that was half the experimental value. 2 This does not necessarily discredit Hall 's work since his cal... been observed in water mixtures of acetone by Willard and of ethyl alcohol by. Willis and by. Burton. Burton 10 11 also found peaks in water mixtures of several alcohols and other organic compounds but failed to observe a peak in those of methyl...

  12. Phase behavior of Ising mixtures.

    PubMed

    Fenz, W; Folk, R

    2005-04-01

    We present phase diagrams that were calculated both in mean-field theory and via Monte Carlo (MC) simulations for binary mixtures of a ferromagnetic Ising fluid and a nonmagnetic fluid (Ising mixtures) in the absence of an external field. We look at both the simple ideal Ising mixture, consisting of an ideal Ising fluid and a hard-sphere fluid, as well as at the general case with one component being a nonideal Ising fluid and the other a van der Waals fluid. It is shown that the mean-field phase diagram of the ideal Ising mixture in the limit of infinite pressure is identical to that of the Blume-Capel model for 3He-4He mixtures. The MC phase diagrams were obtained using the Gibbs ensemble, the cumulant intersection technique, and the multi-histogram re-weighting method, adapted to the semi-grand ensemble. The results are qualitatively compared with mean-field theory, and both types of tri-critical lines occurring there are verified in the computer simulations. PMID:15903723

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

    PubMed Central

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

    2002-01-01

    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 on priority mixtures--priority being determined by (estimated) health risk (= toxicity and exposure). PMID:12634116

  14. Charge transfer and doping at organic/organic interfaces

    NASA Astrophysics Data System (ADS)

    Peisert, H.; Knupfer, M.; Zhang, F.; Petr, A.; Dunsch, L.; Fink, J.

    2003-11-01

    We studied the electronic properties of technically relevant organic/organic interfaces using photoemission spectroscopy. Representatives of organic semiconductors from the family of the phthalocyanines were evaporated onto PEDOT:PSS [mixture of poly-3,4-ethylenedioxy-thiophene and polystyrenesulfonate] thin films, which are often applied as electrode material in organic semiconductor devices. Besides the formation of interface dipoles we observe energetic shifts of the electronic levels of the semiconductors, which are explained by a doping of the organic semiconductor near the interface due to a mixing of the two organic materials within the interface region.

  15. Bayesian Kernel Mixtures for Counts

    PubMed Central

    Canale, Antonio; Dunson, David B.

    2011-01-01

    Although Bayesian nonparametric mixture models for continuous data are well developed, there is a limited literature on related approaches for count data. A common strategy is to use a mixture of Poissons, which unfortunately is quite restrictive in not accounting for distributions having variance less than the mean. Other approaches include mixing multinomials, which requires finite support, and using a Dirichlet process prior with a Poisson base measure, which does not allow smooth deviations from the Poisson. As a broad class of alternative models, we propose to use nonparametric mixtures of rounded continuous kernels. An efficient Gibbs sampler is developed for posterior computation, and a simulation study is performed to assess performance. Focusing on the rounded Gaussian case, we generalize the modeling framework to account for multivariate count data, joint modeling with continuous and categorical variables, and other complications. The methods are illustrated through applications to a developmental toxicity study and marketing data. This article has supplementary material online. PMID:22523437

  16. Carbon mineralization from organic wastes at different composting stages during their incubation with soil

    Microsoft Academic Search

    M. P. Bernal; M. A. Sánchez-Monedero; C. Paredes; A. Roig

    1998-01-01

    The decomposition of seven different organic waste mixtures prepared with sewage sludges, animal manures, city refuse and industrial and plant residues, was studied during their aerobic incubation with soil. The waste mixtures were composted by the Rutgers static pile system, and four samples of each mixture were collected at various composting stages: the initial mixture, and samples taken during the

  17. Unrestricted Mixture Models for Class Identification in Growth Mixture Modeling

    ERIC Educational Resources Information Center

    Liu, Min; Hancock, Gregory R.

    2014-01-01

    Growth mixture modeling has gained much attention in applied and methodological social science research recently, but the selection of the number of latent classes for such models remains a challenging issue, especially when the assumption of proper model specification is violated. The current simulation study compared the performance of a linear…

  18. Genotoxicity of complex chemical mixtures 

    E-print Network

    Phillips, Tracie Denise

    2009-05-15

    .2.12 In Vivo Bioassays..................................................................68 2.2.12.1 DNA Adducts in Mice, Topical Application.........68 2.2.12.2 32P-postlabeling.....................................................69 2.3 Results... IN INFANT MALE MICE EXPOSED TO COMPLEX CHEMICAL MIXTURES........106 3.1 Introduction....................................................................................106 3.2 Materials and Methods...

  19. Philatelic Mixtures and Multimodal Densities

    Microsoft Academic Search

    Alan J. Izenman; Charles J. Sommer

    1988-01-01

    A century ago, postage stamps were printed on a deliberate mixture of different paper types, each having its own thickness characteristics due to poor quality control in paper manufacture. It was not unusual for different types of paper to be used for a single stamp issue, because ordinary white wove paper was often not readily available in quantities necessary for

  20. Plasma polymerization of an ethylene-nitrogen gas mixture

    NASA Technical Reports Server (NTRS)

    Hudis, M.; Wydeven, T.

    1975-01-01

    A procedure has been developed whereby nitrogen can be incorporated into an organic film from an ethylene-nitrogen gas mixture using an internal electrode capacitively coupled radio frequency reactor. The presence of nitrogen has been shown directly by infrared transmittance spectra and electron spectroscopic chemical analysis data, and further indirect evidence was provided by dielectric measurements and by the reverse osmosis properties of the film. Preparation of a nitrogen containing film did not require vapor from an organic nitrogen containing liquid monomer. Some control over the bonding and stoichiometry of the polymer film was provided by the added degree of freedom of the nitrogen partial pressure in the gas mixture. This new parameter strongly affected the dielectric properties of the plasma polymerized film and could affect the reverse osmosis behavior.

  1. Mixture theory-based poroelasticity as a model of interstitial tissue growth

    PubMed Central

    Cowin, Stephen C.; Cardoso, Luis

    2011-01-01

    This contribution presents an alternative approach to mixture theory-based poroelasticity by transferring some poroelastic concepts developed by Maurice Biot to mixture theory. These concepts are a larger RVE and the subRVE-RVE velocity average tensor, which Biot called the micro-macro velocity average tensor. This velocity average tensor is assumed here to depend upon the pore structure fabric. The formulation of mixture theory presented is directed toward the modeling of interstitial growth, that is to say changing mass and changing density of an organism. Traditional mixture theory considers constituents to be open systems, but the entire mixture is a closed system. In this development the mixture is also considered to be an open system as an alternative method of modeling growth. Growth is slow and accelerations are neglected in the applications. The velocity of a solid constituent is employed as the main reference velocity in preference to the mean velocity concept from the original formulation of mixture theory. The standard development of statements of the conservation principles and entropy inequality employed in mixture theory are modified to account for these kinematic changes and to allow for supplies of mass, momentum and energy to each constituent and to the mixture as a whole. The objective is to establish a basis for the development of constitutive equations for growth of tissues. PMID:22184481

  2. Analysis of Analgesic Mixtures: An Organic Chemistry Experiment.

    ERIC Educational Resources Information Center

    Martin, Ned H.

    1981-01-01

    Describes an experiment to analyze commercial analgesic preparations (pain relievers) by silica gel thin layer chromatography, followed by preparative (thick) layer chromatographic separation and spectroscopic analysis. Key difference from similar experiments is that students are responsible for devising suitable solvent systems for the thin layer…

  3. Supercritical extraction of organic mixtures from soil-water slurries 

    E-print Network

    Green, Lynda Ann

    1994-01-01

    reduction in carbon tetrachloride and a 60'io reduction in xylenes. The last stream was a simulated waste stream from an acrylonitrile manufacturing plant containing acrylonitrile, 10 acetonitrile, and water. A multipass extraction for this stream... resulted in a 99. 6ss reduction in acrylonitrile and a 99. 4'/s reduction in acetonitrile. Ghonasgi et al. (1991) studied the removal of benzene, phenol, p-chlorophenol, and m-cresol &om water using supercritical CO, as the solvent and reported...

  4. Implications of chemical mixtures in public health practice.

    PubMed

    de Rosa, C T; El-Masri, H A; Pohl, H; Cibulas, W; Mumtaz, M M

    2004-01-01

    The Agency for Toxic Substances and Disease Registry (ATSDR) is a federal public health agency that investigates and strives to prevent human health problems produced by exposure to toxic chemicals and their mixtures in the environment. Most human exposures involving toxic chemicals or mixtures are thought to originate from environmental and occupational sources; however, concurrent exposures are also likely from other sources, such as prescription and nonprescription drugs, indoor air pollutants, alcohol, and tobacco smoke. Thus, in evaluating the potential hazard following exposure to environmental mixtures, ATSDR not only considers the inherent joint toxicity of the mixture but also the influence of environmental, demographic, occupational, and lifestyle factors. To foster these goals, ATSDR has pursued a Mixtures Research and Assessment Program that consists of three component efforts: trend analysis, joint toxicity assessment, and experimental testing. Through trend analysis, ATSDR sets priorities for environmental mixtures of concern for which joint toxicity assessments are conducted as needed. If data are not available to conduct appropriate assessments, a research agenda is pursued through established extramural mechanisms. Ultimately, the data generated are used to support ATSDR's work at sites involving exposure to chemical mixtures. This pragmatic approach allows testable hypotheses or research needs to be identified and resolved and enhances our understanding of the mechanisms of joint toxicity. Several collaborative and cooperative efforts with national and international organizations such as the Toxicology and Nutrition Office, the Netherlands, and the Department of Energy are being pursued as part of these activities. ATSDR also develops guidance manuals to consistently and accurately apply current methodologies for the joint toxicity assessment of chemicals. Further, expert panels often are assembled to resolve outstanding scientific issues or obtain expert advice on pertinent issues. Recently, the need for studies on chemical mixtures has been proposed as one of the six priority areas the agency identified in its agenda for public health environmental research. This has been reinforced through the agency's close work with communities whose leaders have spoken passionately about their concern for information on exposures to chemical mixtures. The five other priority research areas the agency identified are exposure, susceptible populations, communities and tribal involvement, evaluation/surveillance of health effects, and health promotion/prevention. PMID:15371239

  5. SOLVENT EXTRACTION OF ORGANIC WATER POLLUTANTS

    EPA Science Inventory

    Based on experiments with model systems of known organic water pollutants and environmental samples, conclusions are reached concerning the best general solvent for extraction and the most appropriate methods for related manipulations. Chloroform, methylene chloride-ether mixture...

  6. CLUSTERING CRITERIA AND MULTIVARIATE NORMAL MIXTURES

    EPA Science Inventory

    New clustering criteria for use when a mixture of multivariate normal distributions is an appropriate model are presented. They are derived from maximum likelihood and Bayesian approaches corresponding to different assumptions about the covariance matrices of the mixture componen...

  7. Flexible Regression Modeling using Bayesian Nonparametric Mixtures

    E-print Network

    Lee, Herbie

    nonparametric mixture model for the joint distribution of response and covariates obtain full inference/distributions resulting in flexible inferences and more reliable predictions · Modeling utilizes Dirichlet processFlexible Regression Modeling using Bayesian Nonparametric Mixtures Athanasios Kottas Department

  8. Variable mixture ratio performance through nitrogen augmentation

    NASA Technical Reports Server (NTRS)

    Beichel, R.; Obrien, C. J.; Bair, E. K.

    1988-01-01

    High/variable mixture ratio O2/H2 candidate engine cycles are examined for earth-to-orbit vehicle application. Engine performance and power balance information are presented for the candidate cycles relative to chamber pressure, bulk density, and mixture ratio. Included in the cycle screening are concepts where a third fluid (liquid nitrogen) is used to achieve a variable mixture ratio over the trajectory from liftoff to earth orbit. The third fluid cycles offer a very low risk, fully reusable, low operation cost alternative to high/variable mixture ratio bipropellant cycles. Variable mixture ratio engines with extendible nozzle are slightly lower performing than a single mixture ratio engine (MR = 7:1) with extendible nozzle. Dual expander engines (MR = 7:1) have slightly better performance than the single mixture ratio engine. Dual fuel dual expander engines offer a 16 percent improvement over the single mixture ratio engine.

  9. Anisotropic Characterization of Asphalt Mixtures in Compression 

    E-print Network

    Zhang, Yuqing 1983-

    2012-10-08

    not been well addressed because of the complexity of asphalt mixtures. A comprehensive characterization of the asphalt mixtures in compression was accomplished by mechanistically modeling the inherent anisotropy, viscoelasticity, viscoplasticity...

  10. Entanglement teleportation via Bell Mixture

    E-print Network

    Ghosh, S; Roy, A; Sarkar, D; Sen, U; Ghosh, Sibasish; Kar, Guruprasad; Roy, Anirban; Sarkar, Debasis; Sen, Ujjwal

    2001-01-01

    We investigate the teleportation of the bipartite entangled states through two equally noisy quantum channels, namely mixture of Bell states. There is a particular mixed state channel for which all pure entanglement in a known Schmidt basis remain entangled after teleportation and it happens till the channel state remains entangled. Werner state channel lacks both these features. The relation of these noisy channels with violation of Bell's inequality and 2-E inequality is studied.

  11. Entanglement teleportation via Bell Mixture

    E-print Network

    Sibasish Ghosh; Guruprasad Kar; Anirban Roy; Debasis Sarkar; Ujjwal Sen

    2001-07-10

    We investigate the teleportation of the bipartite entangled states through two equally noisy quantum channels, namely mixture of Bell states. There is a particular mixed state channel for which all pure entanglement in a known Schmidt basis remain entangled after teleportation and it happens till the channel state remains entangled. Werner state channel lacks both these features. The relation of these noisy channels with violation of Bell's inequality and 2-E inequality is studied.

  12. Method of photocatalytic conversion of C-H organics

    DOEpatents

    Camaioni, D.M.; Lilga, M.A.

    1998-01-13

    The present invention is the addition of a semiconductor material and energy to the reaction mixture of organic, acid (for example, trifluoroacetate), and oxygen. A transition metal ion may be added to the reaction mixture. The semiconductor material converts energy to oxidants thereby promoting oxidation of the organic. Alternatively, using metal in combination with exposure to light may be used.

  13. Tutorial on mixture models (2) Christian Hennig

    E-print Network

    Hennig, Christian

    model-based clustering Using mclust (Gaussian mixtures) for aim of clustering. General attitude: models validation by visualisation Stability assessment Gaussian mixture models vs. other clustering methods k -2-10123 za[,1] za[,2] 0 10 20 30 40 50 -2-10123 zb[,1] zb[,2] Gaussian mixture ML is sensitive

  14. Simplex-centroid mixture formulation for optimised composting of kitchen waste.

    PubMed

    Abdullah, N; Chin, N L

    2010-11-01

    Composting is a good recycling method to fully utilise all the organic wastes present in kitchen waste due to its high nutritious matter within the waste. In this present study, the optimised mixture proportions of kitchen waste containing vegetable scraps (V), fish processing waste (F) and newspaper (N) or onion peels (O) were determined by applying the simplex-centroid mixture design method to achieve the desired initial moisture content and carbon-to-nitrogen (CN) ratio for effective composting process. The best mixture was at 48.5% V, 17.7% F and 33.7% N for blends with newspaper while for blends with onion peels, the mixture proportion was 44.0% V, 19.7% F and 36.2% O. The predicted responses from these mixture proportions fall in the acceptable limits of moisture content of 50% to 65% and CN ratio of 20-40 and were also validated experimentally. PMID:20624604

  15. Life-history responses of Daphnia magna Straus to binary mixtures of toxic substances: Pharmacological versus ecotoxicological modes of action

    Microsoft Academic Search

    Carlos Barata; Donald J. Baird; Antonio J. A. Nogueira; Ana Raquel Agra; Amadeu M. V. M. Soares

    2007-01-01

    Two prevailing theoretical models: concentration addition (CA) and independent action (IA), predict mixture toxicity on the basis of known toxicities of the mixture components. To date, both models have been in most occasions evaluated using unicellular in vivo responses or biochemical in vitro responses. However, when considering more complex models such as the whole organism physiology or life-history traits, the

  16. Lack of promotional effects of groundwater contaminant mixtures on the induction of preneoplastic foci in rat liver

    Microsoft Academic Search

    Stephen A. Benjamin; Raymond S. H. Yang; John D. Tessari; Laura W. Chubb; Michael D. Brown; Charles E. Dean; Thomas J. Keefe

    1999-01-01

    F344 rats were exposed to drinking water mixtures of seven of the most common groundwater contaminants associated with hazardous waste sites [arsenic, benzene, chloroform, chromium, lead, phenol, and trichloroethylene (TCE)] as the full mixture or submixtures of the organic and\\/or inorganic chemicals. The lowest concentrations (1×) of the individual chemicals were environmentally realistic and below what would be expected to

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

    PubMed Central

    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

  18. Acute toxicity of binary and ternary mixtures of Cd, Cu, and Zn to Daphnia magna.

    PubMed

    Meyer, Joseph S; Ranville, James F; Pontasch, Mandee; Gorsuch, Joseph W; Adams, William J

    2015-04-01

    Standard static-exposure acute lethality tests were conducted with Daphnia magna neonates exposed to binary or ternary mixtures of Cd, Cu, and Zn in moderately hard reconstituted water that contained 3?mg dissolved organic carbon/L added as Suwannee River fulvic acid. These experiments were conducted to test for additive toxicity (i.e., the response to the mixture can be predicted by combining the responses obtained in single-metal toxicity tests) or nonadditive toxicity (i.e., the response is less than or greater than additive). Based on total metal concentrations (>90% dissolved) the toxicity of the tested metal mixtures could be categorized into all 3 possible additivity categories: less-than-additive toxicity (e.g., Cd-Zn and Cd-Cu-Zn mixtures and Cd-Cu mixtures when Cu was titrated into Cd-containing waters), additive toxicity (e.g., some Cu-Zn mixtures), or more-than-additive toxicity (some Cu-Zn mixtures and Cd-Cu mixtures when Cd was titrated into Cu-containing waters). Exposing the organisms to a range of sublethal to supralethal concentrations of the titrated metal was especially helpful in identifying nonadditive interactions. Geochemical processes (e.g., metal-metal competition for binding to dissolved organic matter and/or the biotic ligand, and possibly supersaturation of exposure waters with the metals in some high-concentration exposures) can explain much of the observed metal-metal interactions. Therefore, bioavailability models that incorporate those geochemical (and possibly some physiological) processes might be able to predict metal mixture toxicity accurately. PMID:25336231

  19. Biofiltration Kinetics of a Gaseous Aldehyde Mixture Using a Synthetic Matrix

    Microsoft Academic Search

    Li Wang; Praveen Kolar; James R. Kastner; Brian Herner; Christian Dye; Kostantinos Eleftheriadis; Eleftheria Katsivela; Donald Martello; Natalie Pekney; Richard Anderson; Cliff Davidson; Philip Hopke; Eugene Kim; William Christensen; Nolan Mangelson; Delbert Eatough; Saqib Mukhtar; Atilla Mutlu; Sergio Capareda; Calvin Parnell; Andrew Rutter; Katy Hanford; Jaime Zwers; Anthony Perillo-Nicholas; James Schauer; Mark Olson; Paul Scott; Deborah Proctor; Yinka Afon; David Ervin; Yifang Zhu; David Fung; Nola Kennedy; William Hinds; Arantzazu Eiguren-Fernandez; David Stieb; Richard Burnett; Marc Smith-Doiron; Orly Brion; Hwashin Shin; Vanita Economou; Rich Cook; Vlad Isakov; Jawad Touma; William Benjey; James Thurman; Ellen Kinnee; Darrell Ensley

    2008-01-01

    Although aldehydes contribute to ozone and particulate matter formation, there has been little research on the biofiltration of these volatile organic compounds (VOCs), especially as mixtures. Biofiltration degradation kinetics of an aldehyde mixture containing hexanal, 2-methylbutanal (2-MB), and 3-methylbutanal (3-MB) was investigated using a bench-scale, synthetic, media-based biofilter. The adsorption capacity of the synthetic media for a model VOC, 3-methylbutanal,

  20. Morphology and crystallization kinetics in a mixture of low-molecular weight aliphatic amide and polylactide

    Microsoft Academic Search

    Joo Young Nam; Masami Okamoto; Hirotaka Okamoto; Mitsuru Nakano; Arimitsu Usuki; Masatoshi Matsuda

    2006-01-01

    Polylactide (PLA)\\/N,N-ethylenebis(12-hydroxystearamide) mixture was prepared by using melt extrusion. The detailed crystallization kinetics and morphology of neat PLA and a mixture were studied by using polarized optical microscopy, light scattering, differential scanning calorimetry, and wide-angle X-ray diffraction analyses. The overall crystallization rate and spherulitic texture of PLA were strongly influenced in presence of the organic additive. The overall crystallization rate

  1. TOXICOKINETIC INTERACTIONS AND SURVIVAL OF HYALELLA AZTECA EXPOSED TO BINARY MIXTURES OF CHLORPYRIFOS, DIELDRIN, AND METHYL MERCURY

    EPA Science Inventory

    Chemical mixture interactions of chlorpyrifos, dieldrin, and methyl mercury were evaluated in Hyalella azteca. Survival of adult and juvenile organisms was evaluated following exposure to individual chemicals and in binary combinations. Binary interactions of the model chemicals...

  2. Thermal conductivity of nanoparticle-fluid mixture.

    SciTech Connect

    Wang, X.; Xu, X.; Choi, S. U.-S.; Energy Technology; Purdue Univ.

    1999-10-01

    Effective thermal conductivity of mixtures of fluids and nanometer-size particles is measured by a steady-state parallel-plate method. The tested fluids contain two types of nanoparticles, Al{sub 2}O{sub 3} and CuO, dispersed in water, vacuum pump fluid, engine oil, and ethylene glycol. Experimental results show that the thermal conductivities of nanoparticle-fluid mixtures are higher than those of the base fluids. Using theoretical models of effective thermal conductivity of a mixture, we have demonstrated that the predicted thermal conductivities of nanoparticle-fluid mixtures are much lower than our measured data, indicating the deficiency in the existing models when used for nanoparticle-fluid mixtures. Possible mechanisms contributing to enhancement of the thermal conductivity of the mixtures are discussed. A more comprehensive theory is needed to fully explain the behavior of nanoparticle-fluid mixtures.

  3. Pervaporation of fluoroethanol\\/water and methacrylic acid\\/water mixtures through PVA composite membranes

    Microsoft Academic Search

    Sang-Man Ahn; Jong-Wook Ha; Jeong-Hoon Kim; Yong-Taek Lee; Soo-Bok Lee

    2005-01-01

    2,2,2-Trifluoroethyl methacrylate (TFEMA) is used in the preparation of functional water-repellent paints and optical fiber coating agents, and is manufactured by esterification of 2,2,2-trifluoroethanol (TFEA) and methacrylic acid (MA) via a dehydration process using azeotropic distillation. To substitute for the hazardous dehydration process, composite-type PVA pervaporation membranes were prepared using glutaraldehyde on a porous polyethersulfone support and their basic pervaporation

  4. Sludge organics bioavailability

    SciTech Connect

    Eiceman, G.E.; Bellin, C.A.; Ryan, J.A.; O'Connor, G.A.

    1991-01-01

    Concern over the bioavailability of toxic organics that can occur in municipal sludges threatens routine land application of sludge. Available data, however, show that concentrations of priority organics in normal sludges are low. Sludges applied at agronomic rates yield chemical concentrations in soil-sludge mixtures 50 to 100 fold lower. Plant uptake at these pollutant concentrations (and at much higher concentrations) is minimal. Chemicals are either (1) accumulated at extremely low levels (PCBs), (2) possibly accumulated, but then rapidly metabolized within plants to extremely low levels (DEHP), or (3) likely degraded so rapidly in soil that only minor contamination occurs (PCP and 2,4-DNP).

  5. Surface and Interfacial Properties of Nonaqueous-Phase Liquid Mixtures Released to the Subsurface at the Hanford Site

    SciTech Connect

    Nellis, Scott; Yoon, Hongkyu; Werth, Charlie; Oostrom, Martinus; Valocchi, Albert J.

    2009-05-01

    Surface and interfacial tensions that arise at the interface between different phases are key parameters affecting Nonaqueous Phase Liquid (NAPL) movement and redistribution in the vadose zone after spill events. In this study, the impact of major additive components on surface and interfacial tensions for organic mixtures and wastewater was investigated. Organic mixture and wastewater compositions are based upon carbon tetrachloride (CT) mixtures released at the Hanford site, where CT was discharged simultaneously with dibutyl butyl phosphonate (DBBP), tributyl phosphate (TBP), dibutyl phosphate (DBP), and a machining lard oil (LO). A considerable amount of wastewater consisting primarily of nitrates and metal salts was also discharged. The tension values measured in this study revealed that the addition of these additive components caused a significant lowering of the interfacial tension with water or wastewater and the surface tension of the wastewater phase in equilibrium with the organic mixtures, compared to pure CT, but had minimal effect on the surface tension of the NAPL itself. These results lead to large differences in spreading coefficients for several mixtures, where the additives caused both a higher (more spreading) initial spreading coefficient and a lower (less spreading) equilibrium spreading coefficient. This indicates that if these mixtures migrate into uncontaminated areas, they will tend to spread quickly, but form a higher residual NAPL saturation after equilibrium, as compared to pure CT. Over time, CT likely volatilizes more rapidly than other components in the originally disposed mixtures and the lard oil and phosphates would become more concentrated in the remaining NAPL, resulting in a lower interfacial tension for the mixture. Spreading coefficients are expected to increase and perhaps change the equilibrated organic mixtures from nonspreading to spreading in water-wetting porous media. These results show that the behavior of organic chemical mixtures should be accounted for in numerical flow and transport models.

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

    SciTech Connect

    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.

  7. Automatic NMR-Based Identification of Chemical Reaction Types in Mixtures of Co-Occurring Reactions

    PubMed Central

    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 1H 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 1H 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 the molecules in the mixtures. PMID:24551112

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

    PubMed

    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 the molecules in the mixtures. PMID:24551112

  9. Organic synthesis in experimental impact shocks

    NASA Technical Reports Server (NTRS)

    McKay, C. P.; Borucki, W. J.

    1997-01-01

    Laboratory simulations of shocks created with a high-energy laser demonstrate that the efficacy of organic production depends on the molecular, not just the elemental composition of the shocked gas. In a methane-rich mixture that simulates a low-temperature equilibrium mixture of cometary material, hydrogen cyanide and acetylene were produced with yields of 5 x 10(17) molecules per joule. Repeated shocking of the methane-rich mixture produced amine groups, suggesting the possible synthesis of amino acids. No organic molecules were produced in a carbon dioxide-rich mixture, which is at odds with thermodynamic equilibrium approaches to shock chemistry and has implications for the modeling of shock-produced organic molecules on early Earth.

  10. SIPCAn (Separation, Isolation, Purification, Characterization, and Analysis): A One-Term, Integrated Project for the Undergraduate Organic Laboratory

    ERIC Educational Resources Information Center

    Dintzner, Matthew R.; Kinzie, Charles R.; Pulkrabek, Kimberly A.; Arena, Anthony F.

    2011-01-01

    SIPCAn, an acronym for separation, isolation, purification, characterization, and analysis, is presented as a one-term, integrated project for the first-term undergraduate organic laboratory course. Students are assigned two mixtures of unknown organic compounds--a mixture of two liquid compounds and a mixture of two solid compounds--at the…

  11. Supercritical Water Mixture (SCWM) Experiment

    NASA Technical Reports Server (NTRS)

    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.

  12. Evaluating the similarity of complex drinking-water disinfection by-product mixtures: overview of the issues.

    PubMed

    Rice, Glenn E; Teuschler, Linda K; Bull, Richard J; Simmons, Jane E; Feder, Paul I

    2009-01-01

    Humans are exposed daily to complex mixtures of environmental chemical contaminants, which arise as releases from sources such as engineering procedures, degradation processes, and emissions from mobile or stationary sources. When dose-response data are available for the actual environmental mixture to which individuals are exposed (i.e., the mixture of concern), these data provide the best information for dose-response assessment of the mixture. When suitable data on the mixture itself are not available, surrogate data might be used from a sufficiently similar mixture or a group of similar mixtures. Consequently, the determination of whether the mixture of concern is "sufficiently similar" to a tested mixture or a group of tested mixtures is central to the use of whole mixture methods. This article provides an overview for a series of companion articles whose purpose is to develop a set of biostatistical, chemical, and toxicological criteria and approaches for evaluating the similarity of drinking-water disinfection by-product (DBPs) complex mixtures. Together, the five articles in this series serve as a case study whose techniques will be relevant to assessing similarity for other classes of complex mixtures of environmental chemicals. Schenck et al. (2009) describe the chemistry and mutagenicity of a set of DBP mixtures concentrated from five different drinking-water treatment plants. Bull et al. (2009a, 2009b) describe how the variables that impact the formation of DBP affect the chemical composition and, subsequently, the expected toxicity of the mixture. Feder et al. (2009a, 2009b) evaluate the similarity of DBP mixture concentrates by applying two biostatistical approaches, principal components analysis, and a nonparametric "bootstrap" analysis. Important factors for determining sufficient similarity of DBP mixtures found in this research include disinfectant used; source water characteristics, including the concentrations of bromide and total organic carbon; concentrations and proportions of individual DBPs with known toxicity data on the same endpoint; magnitude of the unidentified fraction of total organic halides; similar toxicity outcomes for whole mixture testing (e.g., mutagenicity); and summary chemical measures such as total trihalomethanes, total haloacetic acids, total haloacetonitriles, and the levels of bromide incorporation in the DBP classes. PMID:19267305

  13. Polymorphic changes in mixtures of confectionery fats

    Microsoft Academic Search

    N. V. Lovegren; M. S. Gray; R. O. Feuge

    1976-01-01

    The polymorphic behavior of mixtures of cocoa butter and high melting cocoa butter fraction with three types of confectionery\\u000a fats and mixtures of the confectionery fats with each other were investigated with a differential scanning calorimeter. The\\u000a confectionery fats were an interesterified-fractionated fat, a hydrogenated-fractionated fat, and a lauric acid fat. The lowered\\u000a melting point observed in mixtures of confectionery

  14. Deciding which chemical mixtures risk assessment methods work best for what mixtures

    SciTech Connect

    Teuschler, Linda K. [U.S. Environmental Protection Agency, Office of Research and Development, National Center for Environmental Assessment, 26 W. Martin Luther King Dr. (MS-A110), Cincinnati, OH 45268 (United States)], E-mail: teuschler.linda@epa.gov

    2007-09-01

    The most commonly used chemical mixtures risk assessment methods involve simple notions of additivity and toxicological similarity. Newer methods are emerging in response to the complexities of chemical mixture exposures and effects. Factors based on both science and policy drive decisions regarding whether to conduct a chemical mixtures risk assessment and, if so, which methods to employ. Scientific considerations are based on positive evidence of joint toxic action, elevated human exposure conditions or the potential for significant impacts on human health. Policy issues include legislative drivers that may mandate action even though adequate toxicity data on a specific mixture may not be available and risk assessment goals that impact the choice of risk assessment method to obtain the amount of health protection desired. This paper discusses three important concepts used to choose among available approaches for conducting a chemical mixtures risk assessment: (1) additive joint toxic action of mixture components; (2) toxicological interactions of mixture components; and (3) chemical composition of complex mixtures. It is proposed that scientific support for basic assumptions used in chemical mixtures risk assessment should be developed by expert panels, risk assessment methods experts, and laboratory toxicologists. This is imperative to further develop and refine quantitative methods and provide guidance on their appropriate applications. Risk assessors need scientific support for chemical mixtures risk assessment methods in the form of toxicological data on joint toxic action for high priority mixtures, statistical methods for analyzing dose-response for mixtures, and toxicological and statistical criteria for determining sufficient similarity of complex mixtures.

  15. Symmetrical mixtures in external fields

    NASA Astrophysics Data System (ADS)

    Materniak, S.; Patrykiejew, A.

    2013-07-01

    We have studied the behavior of symmetrical binary mixtures of Lennard-Jones particles in contact with strongly adsorbing walls using Monte Carlo simulation methods in the grand canonical and semi-grand canonical ensembles. Two types of the surface potential have been applied. The first depends on the distance from the surface only, while the second involves periodic modulations in the directions parallel to the wall. In the latter case, it has been assumed that the solid substrate is a fcc crystal with the surface being the (100) face. We have considered the systems in which the surface potential is strong enough to induce the layer-by-layer adsorption at low temperatures and discussed the interplay between the demixing transition and the structure of thin films for several systems characterized by different parameters describing the interactions in the system.

  16. Symmetrical mixtures in external fields.

    PubMed

    Materniak, S; Patrykiejew, A

    2013-07-01

    We have studied the behavior of symmetrical binary mixtures of Lennard-Jones particles in contact with strongly adsorbing walls using Monte Carlo simulation methods in the grand canonical and semi-grand canonical ensembles. Two types of the surface potential have been applied. The first depends on the distance from the surface only, while the second involves periodic modulations in the directions parallel to the wall. In the latter case, it has been assumed that the solid substrate is a fcc crystal with the surface being the (100) face. We have considered the systems in which the surface potential is strong enough to induce the layer-by-layer adsorption at low temperatures and discussed the interplay between the demixing transition and the structure of thin films for several systems characterized by different parameters describing the interactions in the system. PMID:23822318

  17. Laboratory simulation of organic grain mantles

    NASA Technical Reports Server (NTRS)

    Mendoza-Gomez, Celia X.; Greenberg, J. M.

    1993-01-01

    Laboratory simulations have been conducted of interstellar space conditions conducive to grain mantle evolution, including the photoproduction of a material which resembles the organic refractory mantle on interstellar grains. Upon analysis by various methods these organic refractory samples are noted to consist of a complex mixture of long, cross-linked chains, with a high probability of being aromatic carbon molecules.

  18. Model-Based Learning Using a Mixture of Mixtures of Gaussian and Uniform Distributions

    Microsoft Academic Search

    Ryan P. Browne; Paul D. McNicholas; Matthew D. Sparling

    2012-01-01

    We introduce a mixture model whereby each mixture component is itself a mixture of a multivariate Gaussian distribution and a multivariate uniform distribution. Although this model could be used for model-based clustering (model-based unsupervised learning) or model-based classification (model-based semi-supervised learning), we focus on the more general model-based classification framework. In this setting, we fit our mixture models to data

  19. Effects of Natural Organic Matter on Stability, Transport and Deposition of Engineered Nano-particles in Porous Media

    EPA Science Inventory

    The interaction of nano-particles and organic substances, like natural organic matter, could have significant influence on the fate, transport and bioavailability of toxic substances. Natural organic matter (NOM) is a mixture of chemically complex polyelectrolytes with varying m...

  20. SAR IMAGES AS MIXTURES OF GAUSSIAN MIXTURES Peter Orbanz and Joachim M. Buhmann

    E-print Network

    Columbia University

    SAR IMAGES AS MIXTURES OF GAUSSIAN MIXTURES Peter Orbanz and Joachim M. Buhmann Institute radar (SAR) images. 1. INTRODUCTION Image segmentation defines a fundamental problem in im- age analysis densities for SAR image processing), as well as bimodal densities. Unsuper- vised learning of mixture models

  1. Blind source separation ofmore sources than mixtures using generalized exponential mixture models

    Microsoft Academic Search

    Zhenwei Shia; Huanwen Tang; Wenyu Liu; Yiyuan Tang

    Blind source separation is discussed with more sources than mixtures in this paper. The blind separation technique includes two steps. The 1rst step is to estimate a mixing matrix, and the second is to estimate sources. Ifthe sources are sparse, the mixing matrix can be estimated by using the generalized exponential mixture model. The generalized exponential mixture model is a

  2. Organic Vegetable Organic Vegetable

    E-print Network

    .......................................6 Safety ................................................................6 Insect Management ...............................19 disease, and weed management. Information on other aspects of vegetable production may be found of management and time invested in developing the system, organic produce should bring a premium price compared

  3. TRANSLATED POISSON MIXTURE MODEL FOR STRATIFICATION LEARNING

    E-print Network

    TRANSLATED POISSON MIXTURE MODEL FOR STRATIFICATION LEARNING By Gloria Haro Gregory Randal for Stratification Learning Gloria Haro Dept. Teoria del Senyal i Comunicacions Universitat Polit`ecnica de Catalunya stratifications, that is, mixture of manifolds repre- senting different characteristics and complexities

  4. Applications of finite mixtures of regression models

    Microsoft Academic Search

    Bettina Gr; Wirtschaftsuniversitat Wien; Friedrich Leisch

    2006-01-01

    Package flexmix provides functionality for fitting finite mixtures of regression models. The available model class includes generalized linear models with varying and fixed effects for the component specific models and multinomial logit models for the concomitant variable models. This model class includes random intercept models where the random part is modelled by a finite mixture instead of a-priori selecting a

  5. On the quantitative genetics of mixture characters.

    PubMed

    Gianola, Daniel; Heringstad, Bjorg; Odegaard, Jorgen

    2006-08-01

    Finite mixture models are helpful for uncovering heterogeneity due to hidden structure. Quantitative genetics issues of continuous characters having a finite mixture of Gaussian components as statistical distribution are explored in this article. The partition of variance in a mixture, the covariance between relatives under the supposition of an additive genetic model, and the offspring-parent regression are derived. Formulas for assessing the effect of mass selection operating on a mixture are given. Expressions for the genetic and phenotypic correlations between mixture and Gaussian traits and between two mixture traits are presented. It is found that, if there is heterogeneity in a population at the genetic or environmental level, then genetic parameters based on theory treating distributions as homogeneous can lead to misleading interpretations. Some peculiarities of mixture characters are: heritability depends on the mean values of the component distributions, the offspring-parent regression is nonlinear, and genetic or phenotypic correlations cannot be interpreted devoid of the mixture proportions and of the parameters of the distributions mixed. PMID:16624917

  6. Modified asphalt mixtures resistance to permanent deformations

    Microsoft Academic Search

    Piotr Radziszewski

    2007-01-01

    Permanent deformations, primarily in the form of ruts, are one of the basic asphalt pavement damages impairing its service properties. Application of appropriate asphalt mixtures and binder modification are effective methods for improving asphalt courses resistance. While being manufactured, stored, fitted into a road pavement and during long term service, bitumen binders and asphalt mixtures are subject to continuous unfavourable

  7. Discrete Mixtures Models Stephane Hess, ETHZ

    E-print Network

    Bierlaire, Michel

    Discrete Mixtures Models Stephane Hess, ETHZ Michel Bierlaire, EPFL John W. Polak, Imperial College-17, 2006 #12;Swiss Transport Research Conference March 15-17, 2006 Discrete Mixtures Models Stephane Hess for Transport Studies ETHZ EPFL Imperial College Zürich Lausanne London stephane.hess@ivt.baug.ethz.ch michel

  8. Process Dissociation and Mixture Signal Detection Theory

    ERIC Educational Resources Information Center

    DeCarlo, Lawrence T.

    2008-01-01

    The process dissociation procedure was developed in an attempt to separate different processes involved in memory tasks. The procedure naturally lends itself to a formulation within a class of mixture signal detection models. The dual process model is shown to be a special case. The mixture signal detection model is applied to data from a widely…

  9. Mixtures of Gaussian Processes Volker Tresp

    E-print Network

    Tresp, Volker

    a Gaussian like- lihood model. GPR can be generalized by using likelihood models from the exponential familyMixtures of Gaussian Processes Volker Tresp Siemens AG, Corporate Technology, Department of Neural the mixture of Gaussian processes (MGP) model which is useful for applications in which the optimal bandwidth

  10. COMPLEX MIXTURES AND GROUND WATER QUALITY

    EPA Science Inventory

    Experience has shown that many soil and ground-water contamination problems involve complex mixtures of chemicals. his manuscript identifies and discusses, in a generic sense, some of the important processes which must be considered when dealing with complex mixtures in the subsu...

  11. Mixtures of Robust Probabilistic Principal Component Analyzers

    E-print Network

    Verleysen, Michel

    mixture of Gaussians is a particular instance of this more general model. 1 Introduction Principal is a heavy tailed generalization of the Gaussian distribution. Similarly, the robust probabilistic Gaussian distributions with Student-t distributions was already proposed in the context of finite mixture

  12. Bayesian Kernel Mixtures for Counts Antonio Canale

    E-print Network

    West, Mike

    . Fo- cusing on the rounded Gaussian case, we generalize the modeling framework to account process (DP) (Ferguson 1973, 1974) mixture of Gaussians kernels (Lo 1984; Escobar and West 1995) to obtain that consistent estimates are obtained. Similar results can be obtained for nonparametric mixtures of various non-Gaussian

  13. RENAL CANCER STUDIES OF DRINKING WATER MIXTURES

    EPA Science Inventory

    Current default risk assessments for chemical mixtures assume additivity of carcinogenic effects but this may under or over represent the actual biological response. A rodent model of hereditary renal cancer (Eker rat) was used to evaluate the carcinogenicity of a mixture of DBPs...

  14. PATTERN CLUSTERING BY MULTIVARIATE MIXTURE ANALYSIS

    Microsoft Academic Search

    JOHN H. WOLFE

    1970-01-01

    Cluster analysis is reformulated as a problem of estimating the para- meters of a mixture of multivariate distributions. The maximum-likelihood theory and numerical solution techniques are developed for a fairly general class of distributions. The theory is applied to mixtures of multivariate nor- mals (\\

  15. Separation of gas mixtures by centrifugation

    NASA Technical Reports Server (NTRS)

    Park, C.; Love, W. L.

    1972-01-01

    Magnetohydrodynamic (MHD) centrifuge utilizing electric currents and magnetic fields produces a magnetic force which develops supersonic rotational velocities in gas mixtures. Device is superior to ordinary centrifuges because rotation of gas mixture is produced by MHD force rather than mechanical means.

  16. Gas mixtures for spark gap closing switches

    DOEpatents

    Christophorou, L.G.; McCorkle, D.L.; Hunter, S.R.

    1987-02-20

    Gas mixtures for use in spark gap closing switches comprised of fluorocarbons and low molecular weight, inert buffer gases. To this can be added a third gas having a low ionization potential relative to the buffer gas. The gas mixtures presented possess properties that optimized the efficiency spark gap closing switches. 6 figs.

  17. Physicochemical Compatibility of Propofol-Lidocaine Mixture

    Microsoft Academic Search

    Yoko Masaki; Makoto Tanaka; Toshiaki Nishikawa

    2003-01-01

    To examine the physicochemical stability of combina- tions of propofol-lidocaine mixtures frequently used in clinical practice, we added lidocaine 5, 10, 20, or 40 mg to commercially available 1% propofol 20 mL. To assess chemical stability, propofol concentrations were deter- mined by gas chromatography assay for 24 h after prep- aration of the mixture. In addition, scanning electron microscopy was

  18. Groundwater phenomena and the theory of mixtures

    SciTech Connect

    Lee, D.W. (Oak Ridge National Lab., TN (USA)); Wineman, A.S. (Michigan Univ., Ann Arbor, MI (USA). Dept. of Mechanical Engineering and Applied Mechanics)

    1991-01-01

    The phenomena of groundwater motion and the recent developments in the Theory of Mixtures are reviewed. Comparisons of these results with those from classical theory are presented. Phenomena of interest that are not well explained are discussed and the potential of the Theory of Mixtures in addressing these phenomena is presented. 16 refs.

  19. Deer preference among various trace mineral mixtures

    E-print Network

    Gray, Matthew

    4/25/2009 1 Deer preference among various trace mineral mixtures Marcus Lashley FWF 512 University Implications #12;4/25/2009 2 JustificationJustification White-tailed deer herd characteristics are commonly estimated using infrared cameras Mineral mixtures can help attract deer to camera sites during summer

  20. Simplifying Mixture Models through Function Approximation

    E-print Network

    Kwok, James Tin-Yau

    that in many learning processes using mixture models (such as particle filtering [6] and non-parametric belief and reliable than using the KL-based distance measure. Moreover, the complexity of our algorithm is only linear-tree [8, 9], for acceleration. Recently, [5] proposes to reduce a large Gaussian mixture into a smaller

  1. Spark ignition of hydrogen-air mixture

    Microsoft Academic Search

    Ryo Ono; Tetsuji Oda

    2008-01-01

    The electrostatic ignition of hydrogen-air mixture is investigated. First, the minimum ignition energy (MIE) of the hydrogen-air mixture is measured using a capacitance spark discharge. The influences of the spark gap length, humidity, and the spark pulse duration on the MIE are studied. It is shown that the MIE is approximately constant when the relative humidity increases from 0% to

  2. Gas mixtures for spark gap closing switches

    DOEpatents

    Christophorou, Loucas G. (Oak Ridge, TN); McCorkle, Dennis L. (Knoxville, TN); Hunter, Scott R. (Oak Ridge, TN)

    1988-01-01

    Gas mixtures for use in spark gap closing switches comprised of fluorocarbons and low molecular weight, inert buffer gases. To this can be added a third gas having a low ionization potential relative to the buffer gas. The gas mixtures presented possess properties that optimized the efficiency spark gap closing switches.

  3. Organic chemistry on Titan

    NASA Technical Reports Server (NTRS)

    Chang, S.; Scattergood, T.; Aronowitz, S.; Flores, J.

    1979-01-01

    Features taken from various models of Titan's atmosphere are combined in a working composite model that provides environmental constraints within which different pathways for organic chemical synthesis are determined. Experimental results and theoretical modeling suggest that the organic chemistry of the satellite is dominated by two processes: photochemistry and energetic particle bombardment. Photochemical reactions of CH4 in the upper atmosphere can account for the presence of C2 hydrocarbons. Reactions initiated at various levels of the atmosphere by cosmic rays, Saturn 'wind', and solar wind particle bombardment of a CH4-N2 atmospheric mixture can account for the UV-visible absorbing stratospheric haze, the reddish appearance of the satellite, and some of the C2 hydrocarbons. In the lower atmosphere photochemical processes will be important if surface temperatures are sufficiently high for gaseous NH3 to exist. It is concluded that the surface of Titan may contain ancient or recent organic matter (or both) produced in the atmosphere.

  4. Editorial: Advances in Self-Organizing Maps The Self-Organizing Map (SOM) with its related extensions is the most popular artificial

    E-print Network

    Paris-Sud XI, Université de

    to superimposed stimulus patterns. This principle can be used for instance to model pointwise neural projections the equivalence between kernel self- organizing maps and self-organizing mixture density networks, an extension

  5. Mixing - Simulating Mixture Problems with Beads

    NSDL National Science Digital Library

    2011-01-01

    This activity, created by Arthur N. DiVito, Ph.D, simulates mixture problems by using red and white colored beads. Mixture A is 70% red, and mixture B is 40% red (as determined by weight). The students are asked to created a "solution" with a given weight whose concentration of red is between 40% and 70% using the above solutions. Students empirically verify the final "solution" has the proper percent of red beads by separating colors and weighing them separately. As the author mentions, many students have difficult with mixture problems because they don't understand percents well. This hands on activity gives a tangible representation of percents in addition to the overarching concepts needed to solve mixture problems.

  6. Genotoxicity of complex mixtures: CHO cell mutagenicity assay

    SciTech Connect

    Frazier, M.E.; Samuel, J.E.

    1985-02-01

    A Chinese hamster ovary (CHO) mammalian cell assay was used to evaluate the genotoxicity of complex mixtures (synthetic fuels). The genotoxicity (mutagenic potency) of the mixtures increased as the temperature of their boiling range increased. Most of the genotoxicity in the 750/sup 0/F+ boiling-range materials was associated with the neutral polycyclic aromatic hydrocarbon (PAH) fractions. Chemical analysis data indicate that the PAH fractions of high-boiling coal liquids contain a number of known chemical carcinogens, including five- and six-ring polyaromatics (e.g., benzo(a)pyrene) as well as four- and five-ring alkyl-substituted PAH (e.g., methylchrysene and dimethylbenzanthracenes); concentrations are a function of boiling point (bp). In vitro genotoxicity was also detected in fractions of nitrogen-containing polyaromatic compounds, as well as in those with aliphatics of hydroxy-containing PAH. Mutagenic activity of some fractions was detectable in the CHO assay in the absence of an exogenous metabolic activation system; in some instances, addition of exogenous enzymes and cofactors inhibited expression of the direct-acting mutagenic potential of the fraction. These data indicate that the organic matrix of the chemical fraction determines whether, and to what degree, various mutagens are expressed in the CHO assay. Therefore, the results of biological assays of these mixtures must be correlated with chemical analyses for proper interpretation of these data. 29 references, 16 figures, 4 tables.

  7. Biodegradability of chlorophenols and mixtures of chlorophenols in seawater

    SciTech Connect

    Lindgaard-Jorgensen, P.

    1989-04-01

    Laboratory studies using chemical concentrations comparable to those found in nature have provided considerable knowledge of microbial transformations in nature. Although the number of studies performed is increasing rapidly, the effects of low substrate levels on growth, enzyme induction, enzyme activity, and the use of mixtures of substrates have not yet been clarified. Likewise, studies at low concentrations in seawater are lacking. This paper describes a study of the rates of degradation of chlorophenols 4-chlor-2-methylphenol, 2,4-dichlorophenol (2,4-DCP), and 2,4,6-trichlorophenol at concentrations ranging from 2 to 18 micrograms/liter. The compounds were tested separately, in a mixture, and in waste water containing other organics. The obtained rates of 2,4-DCP in seawater were comparable to those found in fresh water. Also, the rates were in general agreement with a kinetic model proposed for degradation of chlorophenols. The rates of degradation of chlorophenols in the mixture were comparable to those found when tested separately. In the waste, very low rates were observed. It is suggested that this might be explained by a toxic effect, caused by other substances in the waste water, on the microorganisms considered to be active in degrading the chlorophenols at low concentrations.

  8. ICA MIXTURE MODELS FOR UNSUPERVISED CLASSIFICATION AND AUTOMATIC CONTEXT SWITCHING

    E-print Network

    Lee, Te-Won

    mixture model. We generalize the Gaussian mixture model by modeling each class with a mixture mixture model so that the clusters can have non­Gaussian structure. Performance on a standard classification accurately over stan­ dard Gaussian mixture models. We also show that the algorithm can be applied

  9. Method for destroying hazardous organics and other combustible materials in a subcritical/supercritical reactor

    DOEpatents

    Janikowski, Stuart K. (Idaho Falls, ID)

    2000-01-01

    A waste destruction method using a reactor vessel to combust and destroy organic and combustible waste, including the steps of introducing a supply of waste into the reactor vessel, introducing a supply of an oxidant into the reactor vessel to mix with the waste forming a waste and oxidant mixture, introducing a supply of water into the reactor vessel to mix with the waste and oxidant mixture forming a waste, water and oxidant mixture, reciprocatingly compressing the waste, water and oxidant mixture forming a compressed mixture, igniting the compressed mixture forming a exhaust gas, and venting the exhaust gas into the surrounding atmosphere.

  10. Unified Maxwell–Stefan description of binary mixture diffusion in micro- and meso-porous materials

    Microsoft Academic Search

    R. Krishna; J. M. van Baten

    2009-01-01

    The Maxwell–Stefan (M–S) formulation for binary mixture diffusion in micro-porous materials such as zeolites, metal organic frameworks (MOFs), and covalent organic frameworks (COFs), that have pore sizes typically smaller than 2nm, is formulated in a manner that is consistent with corresponding description for meso-porous systems. The M–S equations are set up in terms of species concentrations, ci, defined in terms

  11. Determinants of Whether or Not Mixtures of Disinfection By-Products are Similar

    Microsoft Academic Search

    Richard J. Bull; Glenn Rice; Linda K. Teuschler

    2009-01-01

    Reactive chemicals have been used to disinfect drinking waters for over a century. In the 1970s, it was first observed that the reaction of these chemicals with the natural organic matter (NOM) in source waters results in the production of variable, complex mixtures of disinfection by-products (DBP). Because limited toxicological and epidemiological data are available to assess potential human health

  12. Photocatalytic oxidation of 2-propanol\\/toluene binary mixtures at indoor air concentration levels

    Microsoft Academic Search

    Daniel Vildozo; Raquel Portela; Corinne Ferronato; Jean-Marc Chovelon

    2011-01-01

    Photocatalytic oxidation (PCO) technology has a great potential for indoor air purification. However, the presence of humidity and different concentrations of a variety of pollutants are critical parameters that must be addressed for indoor air cleaning applications. In this work, the photodegradation over a commercial air cleaning TiO2 filter of a mixture of two common volatile organic compounds (VOCs), 2-propanol

  13. Qualitative and quantitative analysis of mixtures of compounds containing both hydrogen and deuterium

    NASA Technical Reports Server (NTRS)

    Crespi, H. L.; Harkness, L.; Katz, J. J.; Norman, G.; Saur, W.

    1969-01-01

    Method allows qualitative and quantitative analysis of mixtures of partially deuterated compounds. Nuclear magnetic resonance spectroscopy determines location and amount of deuterium in organic compounds but not fully deuterated compounds. Mass spectroscopy can detect fully deuterated species but not the location.

  14. Toxaphene congeners differ from toxaphene mixtures in their dysmorphogenic effects on cultured rat embryos

    Microsoft Academic Search

    Cristina Calciu; Hing Man Chan; Stan Kubow

    1997-01-01

    The presence of persistent organic pollutants, including the pesticide toxaphene has been reported even in remote regions such as the Arctic and is becoming a health concern. The technical mixture of toxaphene contains over 800 different congeners. The numbers of prevalent congeners, however, decrease along the food chain. About 20 major congeners are found in fish, eight in marine mammals

  15. Use of straight vegetable oil mixtures of rape and camelina as on farm fuels in agriculture

    Microsoft Academic Search

    Hans Marten Paulsen; V. Wichmann; U. Schuemann; B. Richter

    2011-01-01

    Possibilities for using straight vegetable oil (SVO) from Camelina sativa (L.) Crantz (camelina or false flax) and its mixtures with Brassica napus (rape) SVO as fuel in adapted diesel engines are described with chemical parameters, measurements in a test engine and a field test in a tractor. Camelina as a crop is attracting attention in organic farming and is often

  16. Reproducibility of binary-mixture toxicity studies.

    PubMed

    Cedergreen, Nina; Kudsk, Per; Mathiassen, Solvejg Kopp; Sørensen, Helle; Streibig, Jens Carl

    2007-01-01

    Binary-mixture studies often are conducted with the aim of elucidating the effect of one specific chemical on the biological action of another. The results can be interpreted in relation to reference models by the use of response-surface analyses and isobolograms. The amount of data needed for these analyses is, however, extensive, and the experiments therefore rarely are repeated. In the present study, we investigate the reproducibility of isobole shapes of binary-mixture toxicity experiments in terms of deviation from the reference model of concentration addition (CA), dose-level dependence, and isobole asymmetry. We use data from four herbicide mixtures tested in three to five independent experiments on the aquatic test plant Lemna minor and the terrestrial plant Tripleurospermum inodorum. The results showed that the variation both within and among experiments was approximately half the size for the aquatic test system compared to the terrestrial system. As a consequence, a consistent deviation from CA could be obtained in three of four herbicide mixtures for L. minor, whereas this was only the case for one or two of the herbicide mixtures tested on T. inodorum. For one mixture on T. inodorum, both CA synergism and antagonism were detected. Dose-dependent effects could not be repeated consistently, just as the asymmetry found in some isoboles could not. The study emphasizes the importance of repeating mixture toxicity experiments, especially for test systems with large variability, and using caution when drawing biological conclusions from the test results. PMID:17269472

  17. Estrogenic activity of UV filter mixtures

    SciTech Connect

    Kunz, Petra Y. [University of Applied Sciences Northwestern Switzerland (FHNW), School of Life Sciences, Institute of Ecopreneurship, Gruendenstrasse 40, CH-4132 Muttenz (Switzerland) and University of Zuerich, Institute of Plant Biology, Limnology, CH-8802 Kilchberg (Switzerland)]. E-mail: petra.kunz@fhnw.ch; Fent, Karl [University of Applied Sciences Northwestern Switzerland (FHNW), School of Life Sciences, Institute of Ecopreneurship, Gruendenstrasse 40, CH-4132 Muttenz (Switzerland) and Swiss Federal Institute of Technology (ETH), Department of Environmental Sciences, CH-8092 Zurich (Switzerland)]. E-mail: karl.fent@bluewin.ch

    2006-11-15

    UV-absorbing chemicals (UV filters) are widely used for protection against UV radiation in sunscreens and in a variety of cosmetic products and materials. Depending on the breadth and factor of UV protection, they are added as single compounds or as a combination thereof. Some UV filters have estrogenic activity, but their activity and interactions in mixtures are largely unknown. In this work, we analyzed 8 commonly used UV filters, which are pure or partial hER{alpha} agonists, for their estrogenic activity in equieffective mixtures in a recombinant yeast assay carrying the human estrogen receptor alpha (hER{alpha}). Mixtures of two, four and eight UV filters alone, or in combination with 17 {beta} estradiol (E2), were assessed at different effect levels and no-observed-effect-concentrations (NOEC). Predictions of the joint effects of these mixtures were calculated by employing the concentration addition (Canada) and independent action (IA) model. Most binary mixtures comprising of pure hER{alpha} agonists showed a synergistic activity at all mixture combinations. Only in combination with benzophenone-1, antagonistic activity was observed at some effect levels. All mixtures of four or eight, pure or pure and partial hER{alpha} agonists, alone or including E2, showed synergistic activity at concentrations giving an increase of 10% of basal activity (BC10). This occurred even at concentrations that were at the NOEC level of each single compound. Hence, there were substantial mixture effects even though each UV filter was present at its NOEC level. These results show that significant interactions occur in UV filter mixtures, which is important for the hazard and risk assessments of these personal care products.

  18. Cosolvency and sorption of hydrophobic organic chemicals

    Microsoft Academic Search

    P. Suresh; C. Rao; L. S. Lee; R. Pinal

    1990-01-01

    Sorption of hydrophobic organic chemicals (HOCs) by two soils was measured from mixed solvents containing water plus completely miscible organic solvents (CMOSs) and partially miscible organic solvents (PMOSs). The utility of the log-linear cosolvency model for predicting HOC sorption from solvent mixtures was evaluated. Co-solvent effects of PMOSs on HOC solubility and sorption were compared. Nonpolar PMOSs (e.g., toluene, p-xylene,

  19. ISOLATION OF ORGANIC WATER POLLUTANTS BY XAD RESINS AND CARBON

    EPA Science Inventory

    The recovery efficiencies of XAD resins -2, -4, -7, and -8 and of resin mixtures were measured using distilled water samples containing 13 organic pollutants. An equal-weight mixture of XAD-4 and XAD-8 was most efficient. XAD-2 and XAD-4/8 were further tested and found effective ...

  20. Thermophobicity of liquids: Heats of transport in mixtures as pure component properties—The case of arbitrary concentration

    NASA Astrophysics Data System (ADS)

    Hartmann, S.; Wittko, G.; Schock, F.; Groß, W.; Lindner, F.; Köhler, W.; Morozov, K. I.

    2014-10-01

    We have measured Soret coefficients of a large number of binary mixtures of 23 different organic solvents. The present analysis is based on 77 equimolar mixtures and strongly supports the thermophobicity concept previously developed for the heats of transport of originally 10 different substances [S. Hartmann, G. Wittko, W. Köhler, K. I. Morozov, K. Albers, and G. Sadowski, Phys. Rev. Lett. 109, 065901 (2012)]. Among the investigated compounds, cis-decalin is the most thermophobic, hexane the most thermophilic one. In addition to the equimolar mixtures, we have also analyzed the composition dependence of the Soret coefficients and the heats of transport for 22 selected binary mixtures. Both the interpretation of the heats of transport in equimolar mixtures as pure component thermophobicities and the composition dependence of the Soret coefficient can be understood on the basis of the thermodiffusion theory developed by Morozov [Phys. Rev. E 79, 031204 (2009)], according to which the composition dependence is determined by the excess volume of mixing.

  1. Liquid-phase and vapor-phase dehydration of organic/water solutions

    DOEpatents

    Huang, Yu (Palo Alto, CA); Ly, Jennifer (San Jose, CA); Aldajani, Tiem (San Jose, CA); Baker, Richard W. (Palo Alto, CA)

    2011-08-23

    Processes for dehydrating an organic/water solution by pervaporation or vapor separation using fluorinated membranes. The processes are particularly useful for treating mixtures containing light organic components, such as ethanol, isopropanol or acetic acid.

  2. Industrial Utilization of Coal-Oil Mixtures

    E-print Network

    Dunn, J. E.; Hawkins, G. T.

    1982-01-01

    Coal-oil mixtures (COM) are receiving increasing interest as economical alternatives to residual fuel oil and natural gas used in heavy industrial and utility applications. Four basic approaches are currently employed in the manufacture of COM...

  3. Separation of gas mixtures including hydrogen

    SciTech Connect

    Krishnamurthy, R.; Lerner, S.L.; Shukla, Y.; Stokley, A.G.

    1993-08-10

    A process is described of separating a gas mixture comprising at least three components into three different fractions by pressure swing adsorption, comprising repeatedly performing a cycle including: passing said gas mixture sequentially through first and second adsorptive regions on each of which a second component of the mixture is more strongly adsorbed than a first component, but less strongly adsorbed than a third component; withdrawing a first fraction enriched in said first component from the downstream end of the second adsorptive region; stopping admission of the said gas mixture to the first adsorptive region; withdrawing a second fraction enriched in the second component from the downstream end of the first adsorptive region and from the upstream end of the second adsorptive region into a common pipeline; and withdrawing a third fraction enriched in the third component from the upstream end of the first adsorptive region.

  4. Binary mixture flammability characteristics for hazard assessment 

    E-print Network

    Vidal Vazquez, Migvia del C.

    2005-11-01

    calculations and UNIFAC, a theoretical model that does not require experimental binary interaction parameters, are employed in the mixture flash point predictions, which are validated with experimental data. MFPB is successfully predicted using the UNIFAC model...

  5. Analysis for Mixtures of Fluids Dissertation

    E-print Network

    Rauhut, Holger

    , such as plasma or mixtures of gases surrounding celestial bodies, blood and biological tissues, suspen- sions as the conservation of mass and the balance of momentum are stated separately for each of the components

  6. Uncertainty in Mixtures and Cumulative Risk Assessment

    EPA Science Inventory

    Uncertainty in Mixtures and Cumulative Risk Assessment JC Lipscomb and GE Rice U.S. Environmental Protection Agency, Office of Research and Development, National Center for Environmental Assessment, Cincinnati, Ohio, USA Humans and environmental species are rarely exposed to sing...

  7. Terahertz spectroscopy for quantifying refined oil mixtures.

    PubMed

    Li, Yi-nan; Li, Jian; Zeng, Zhou-mo; Li, Jie; Tian, Zhen; Wang, Wei-kui

    2012-08-20

    In this paper, the absorption coefficient spectra of samples prepared as mixtures of gasoline and diesel in different proportions are obtained by terahertz time-domain spectroscopy. To quantify the components of refined oil mixtures, a method is proposed to evaluate the best frequency band for regression analysis. With the data in this frequency band, dualistic linear regression fitting is used to determine the volume fraction of gasoline and diesel in the mixture based on the Beer-Lambert law. The minimum of regression fitting R-Square is 0.99967, and the mean error of fitted volume fraction of 97# gasoline is 4.3%. Results show that refined oil mixtures can be quantitatively analyzed through absorption coefficient spectra in terahertz frequency, which it has bright application prospects in the storage and transportation field for refined oil. PMID:22907017

  8. Industrial Utilization of Coal-Oil Mixtures 

    E-print Network

    Dunn, J. E.; Hawkins, G. T.

    1982-01-01

    Coal-oil mixtures (COM) are receiving increasing interest as economical alternatives to residual fuel oil and natural gas used in heavy industrial and utility applications. Four basic approaches are currently employed in the manufacture of COM...

  9. 14 CFR 23.1147 - Mixture controls.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...Simultaneous control of all engines. (2) The controls must require a separate and distinct operation to move the control toward lean or shut-off position. (b) For reciprocating single-engine airplanes, each manual engine mixture control must...

  10. Establishment of three permanent cover crop seed mixtures in Hungarian vineyards

    NASA Astrophysics Data System (ADS)

    Miglécz, Tamas; Valkó, Orsolya; Donkó, Ádám; Deák, Balázs; Török, Péter; Kelemen, András; Drexler, Dóra; Tóthmérész, Béla

    2015-04-01

    In organic vineyard farming sowing high diversity cover crop seed mixtures offers a great opportunity to overcome high-priority problems mitigating vineyard cultivation, such as gain erosion control, save soil fertility, improve soil microbial activity and control weeds. Furthermore, we can also improve the biodiversity and ecosystem services of vineyards. Mainly non-native or low diversity seed mixtures are used for cover cropping containing some grass, grain or Fabaceae species. We studied vegetation development after sowing native high-diversity seed mixtures in four vineyards in an on farm field trial. We compared the effects of 4 treatments: (i) Biocont-Ecowin mixture (12 species), (ii) Fabaceae mixture (9 species), (iii) Grass-forb mixture (16 species) and control (no seed sowing). Study sites were located in Tokaj wine region, East Hungary. Seed mixtures were sown in March, 2012. After sowing, we recorded the percentage cover of vascular plant species in the end of June 2012, 2013 and 2014 in altogether 80 permanent plots. In the first year the establishment and weed control of Biocont-Ecowin and Legume seed mixture was the best. For the second year in inter-rows sown with Grass-herb and Legume seed mixtures we detected decreasing weed cover scores, while in inter-rows sown with Biocont-Ecowin seed mixture and in control inter-rows we detected higher weed cover scores. In the third year we still detected lower weed cover scores in inter-rows sown with Grass-forb and Legume seed mixtures, however on several sites we also detected decreasing cover of sown species. All sown species were detected in our plots during the time of the study, however some species were present only with low cover scores or only in a few plots. Out of the sown species Lotus corniculatus, Medicago lupulina, Plantago lanceolata, Trifolium repens, T. pratense and Coronilla varia established the most successfully, and had high cover scores on most sites even in the second and third year. Our trial to develop species rich cover crops was successful. According to our findings sowing high-diversity seed mixtures in cover cropping offers a good opportunity to gain weed control.

  11. Acute and subacute toxicities of the saponin mixture isolated from Schefflera leucantha Viguier.

    PubMed

    Witthawaskul, P; Panthong, Ampai; Kanjanapothi, D; Taesothikul, T; Lertprasertsuke, N

    2003-11-01

    Acute toxicity of the bronchodilator saponin mixture isolated from Schefflera leucantha Viguier leaves was investigated in comparison with the methanol and the water extract of this plant. Oral doses of 5000 mg/kg of the methanol extract, the water extract and the saponin mixture did not produce mortality or significant changes in the general behavior and gross appearance of internal organs of rats. Subacute toxicity of the saponin mixture was evaluated with the dose of 1000 mg/kg, orally for 14 days. An extra group (satellite group) was given saponin mixture and kept for a further 14 days after treatment. All animals did not show signs of toxicity during the experimental period. Liver weights of the saponin-treated and the satellite male groups were higher whereas testis weight were lower than those of the control group which received distilled water. However, the histological examination of various organs revealed that there were no differences between the control and the treated rats. BUN, Cr, AST, ALT and ALP levels increased in saponin-receiving rats. It is possible that the saponin mixture directly impacts on the liver and the kidney functions. PMID:14522442

  12. Predicting skin permeability from complex chemical mixtures.

    PubMed

    Riviere, Jim E; Brooks, James D

    2005-10-15

    Occupational and environmental exposure to topical chemicals is usually in the form of complex chemical mixtures, yet risk assessment is based on experimentally derived data from individual chemical exposures from a single, usually aqueous vehicle, or from computed physiochemical properties. We present an approach using hybrid quantitative structure permeation relationships (QSPeR) models where absorption through porcine skin flow-through diffusion cells is well predicted using a QSPeR model describing the individual penetrants, coupled with a mixture factor (MF) that accounts for physicochemical properties of the vehicle/mixture components. The baseline equation is log k(p) = c + mMF + a sigma alpha2(H) + b sigma beta2(H) + s pi2(H) + rR2 + vV(x) where sigma alpha2(H) is the hydrogen-bond donor acidity, sigma beta2(H) is the hydrogen-bond acceptor basicity, pi2(H) is the dipolarity/polarizability, R2 represents the excess molar refractivity, and V(x) is the McGowan volume of the penetrants of interest; c, m, a, b, s, r, and v are strength coefficients coupling these descriptors to skin permeability (k(p)) of 12 penetrants (atrazine, chlorpyrifos, ethylparathion, fenthion, methylparathion, nonylphenol, rho-nitrophenol, pentachlorophenol, phenol, propazine, simazine, and triazine) in 24 mixtures. Mixtures consisted of full factorial combinations of vehicles (water, ethanol, propylene glycol) and additives (sodium lauryl sulfate, methyl nicotinate). An additional set of 4 penetrants (DEET, SDS, permethrin, ricinoleic acid) in different mixtures were included to assess applicability of this approach. This resulted in a dataset of 16 compounds administered in 344 treatment combinations. Across all exposures with no MF, R2 for absorption was 0.62. With the MF, correlations increased up to 0.78. Parameters correlated to the MF include refractive index, polarizability and log (1/Henry's Law Constant) of the mixture components. These factors should not be considered final as the focus of these studies was solely to determine if knowledge of the physical properties of a mixture would improve predicting skin permeability. Inclusion of multiple mixture factors should further improve predictability. The importance of these findings is that there is an approach whereby the effects of a mixture on dermal absorption of a penetrant of interest can be quantitated in a standard QSPeR model if physicochemical properties of the mixture are also incorporated. PMID:16183383

  13. Variational Theory of Mixtures in Continuum Mechanics

    E-print Network

    Boyer, Edmond

    Variational Theory of Mixtures in Continuum Mechanics Henri Gouin C.N.R.S. U.M.R. 6181 & Universit of fluid mixtures. PACS: 46.15.Cc; 47.51.+a; 47.55.-t; 64.75Cd. Email address: henri.gouin@univ-cezanne.fr (Henri Gouin). Preprint submitted to European Journal of Mechanics, B/Fluids, vol. 9, No 5, pp. 469

  14. Thermal conductivity of nanoparticle-fluid mixture

    Microsoft Academic Search

    X. Wang; Xianfan Xu

    1999-01-01

    Effective thermal conductivity of mixtures of fluids and nanometer-size particles is measured by a steady-state parallel-plate method. The tested fluids contain two types of nanoparticles, AlâOâ and CuO, dispersed in water, vacuum pump fluid, engine oil, and ethylene glycol. Experimental results show that the thermal conductivities of nanoparticle-fluid mixtures are higher than those of the base fluids. Using theoretical models

  15. A Gaussian mixture ensemble transform filter

    E-print Network

    Reich, Sebastian

    2011-01-01

    We generalize the popular ensemble Kalman filter to an ensemble transform filter where the prior distribution can take the form of a Gaussian mixture. The design of the filter is based on a continuous formulation of the Bayesian filter analysis step. We call the new filter algorithm the ensemble Gaussian mixture filter (EGMF). The EGMF is implemented for two simple test problems (Brownian dynamics in one dimension and a modified Lorenz-96 model).

  16. Infinite Generalized Gaussian Mixture Modeling and Applications

    Microsoft Academic Search

    Tarek Elguebaly; Nizar Bouguila

    \\u000a A fully Bayesian approach to analyze infinite multidimensional generalized Gaussian mixture models (IGGM) is developed in\\u000a this paper. The Bayesian framework is used to avoid model overfitting and the infinite assumption is adopted to avoid the\\u000a difficult problem of finding the right number of mixture components. The utility of the proposed approach is demonstrated\\u000a by applying it on texture classification

  17. Asbestos tailings as aggregates for asphalt mixture

    Microsoft Academic Search

    Xiaoming Liu; Linrong Xu

    2011-01-01

    To use many asbestos tailings collected in Ya-Lu highway, and to explore the feasibility of using asbestos tailings as aggregates\\u000a in common asphalt mixtures, and properties of some asphalt mixtures were evaluated as well. X-ray diffraction (XRD), X-ray\\u000a fluorescent (XRF), and atomic absorption spectrophotometry (AAS) were employed to determine the solid waste content of copper,\\u000a zinc, lead, and cadmium. Volume

  18. Speaker Verification Using Adapted Gaussian Mixture Models

    Microsoft Academic Search

    Douglas A. Reynolds; Thomas F. Quatieri; Robert B. Dunn

    2000-01-01

    Reynolds, Douglas A., Quatieri, Thomas F., and Dunn, Robert B., Speaker Verification Using Adapted Gaussian Mixture Models, Digital Signal Processing10(2000), 19–41.In this paper we describe the major elements of MIT Lincoln Laboratory's Gaussian mixture model (GMM)-based speaker verification system used successfully in several NIST Speaker Recognition Evaluations (SREs). The system is built around the likelihood ratio test for verification, using

  19. Separation of Convolutive Mixtures with Hybrid Sources

    Microsoft Academic Search

    Christine Servière

    2009-01-01

    We propose in this paper a unique method to separate sources that may have different statistical properties, in the case of\\u000a FIR convolutive mixtures. No constraint is necessary on the source statistics (i.i.d variables, Gaussian sources or temporally\\u000a correlated sources..), nor on the number of each type of sources. On the contrary of previous works, no assumption of overdetermined\\u000a mixtures

  20. Non-electrolyte viscous liquid mixtures 

    E-print Network

    Wakefield, Dawn Lee

    1982-01-01

    progress has been made in measuring some ternary and higher component systems, but again over limited temperature ranges. Results described in this thesis include reasons for the failure of previously proposed empirical and statistical mechanical..., for simple binary and ternary mixtures. Also, these equations are not readily extendable to higher component systems since it is not yet understood how intermolecular differences should be compensated for in the mixture viscosity value. The situation...

  1. Turbulent Combustion of Hydrogen–CO Mixtures

    Microsoft Academic Search

    Alexey A. Burluka; Ahmed M. T. El-Dein Hussin; Christopher G. W. Sheppard; Kexin Liu; Victoria Sanderson

    2011-01-01

    Laminar and turbulent burning velocities were measured in a closed-volume fan-stirred vessel for H2–CO mixtures using two independent methods of flame definition. It has been shown that the unsteady flame development is an\\u000a important factor and it needs to be taken into account for comparison of the burning rates obtained in different experiments.\\u000a For the atmospheric pressure flames, the mixtures

  2. Flash evaporation of liquid monomer particle mixture

    DOEpatents

    Affinito, J.D.; Darab, J.G.; Gross, M.E.

    1999-05-11

    The present invention is a method of making a first solid composite polymer layer. The method has the steps of (a) mixing a liquid monomer with particles substantially insoluble in the liquid monomer forming a monomer particle mixture; (b) flash evaporating the particle mixture and forming a composite vapor; and (c) continuously cryocondensing said composite vapor on a cool substrate and cross-linking the cryocondensed film thereby forming the polymer layer. 3 figs.

  3. Flash evaporation of liquid monomer particle mixture

    DOEpatents

    Affinito, John D. (Kennewick, WA); Darab, John G. (Richland, WA); Gross, Mark E. (Pasco, WA)

    1999-01-01

    The present invention is a method of making a first solid composite polymer layer. The method has the steps of (a) mixing a liquid monomer with particles substantially insoluble in the liquid monomer forming a monomer particle mixture; (b) flash evaporating the particle mixture and forming a composite vapor; and (c) continuously cryocondensing said composite vapor on a cool substrate and cross-linking the cryocondensed film thereby forming the polymer layer.

  4. Application of the Electronic Nose Technique to Differentiation between Model Mixtures with COPD Markers

    PubMed Central

    Dymerski, Tomasz; G?bicki, Jacek; Wi?niewska, Paulina; ?liwi?ska, Magdalena; Wardencki, Waldemar; Namie?nik, Jacek

    2013-01-01

    The paper presents the potential of an electronic nose technique in the field of fast diagnostics of patients suspected of Chronic Obstructive Pulmonary Disease (COPD). The investigations were performed using a simple electronic nose prototype equipped with a set of six semiconductor sensors manufactured by FIGARO Co. They were aimed at verification of a possibility of differentiation between model reference mixtures with potential COPD markers (N,N-dimethylformamide and N,N-dimethylacetamide). These mixtures contained volatile organic compounds (VOCs) such as acetone, isoprene, carbon disulphide, propan-2-ol, formamide, benzene, toluene, acetonitrile, acetic acid, dimethyl ether, dimethyl sulphide, acrolein, furan, propanol and pyridine, recognized as the components of exhaled air. The model reference mixtures were prepared at three concentration levels—10 ppb, 25 ppb, 50 ppb v/v—of each component, except for the COPD markers. Concentration of the COPD markers in the mixtures was from 0 ppb to 100 ppb v/v. Interpretation of the obtained data employed principal component analysis (PCA). The investigations revealed the usefulness of the electronic device only in the case when the concentration of the COPD markers was twice as high as the concentration of the remaining components of the mixture and for a limited number of basic mixture components. PMID:23591962

  5. Investigation on minimum ignition energy of mixtures of ?-pinene-benzene/air.

    PubMed

    Coudour, B; Chetehouna, K; Rudz, S; Gillard, P; Garo, J P

    2015-02-11

    Minimum ignition energies (MIE) of ?-pinene-benzene/air mixtures at a given temperature for different equivalence ratios and fuel proportions are experimented in this paper. We used a cylindrical chamber of combustion using a nanosecond pulse at 1,064 nm from a Q-switched Nd:YAG laser. Laser-induced spark ignitions were studied for two molar proportions of ?-pinene/benzene mixtures, respectively 20-80% and 50-50%. The effect of the equivalence ratio (?) has been investigated for 0.7, 0.9, 1.1 and 1.5 and ignition of fuel/air mixtures has been experimented for two different incident laser energies: 25 and 33 mJ. This study aims at observing the influence of different ?-pinene/benzene proportions on the flammability of the mixture to have further knowledge of the potential of biogenic volatile organic compounds (BVOCs) and smoke mixtures to influence forest fires, especially in the case of the accelerating forest fire phenomenon (AFF). Results of ignition probability and energy absorption are based on 400 laser shots for each studied fuel proportions. MIE results as functions of equivalence ratio compared to data of pure ?-pinene and pure benzene demonstrate that the presence of benzene in ?-pinene-air mixture tends to increase ignition probability and reduce MIE without depending strongly on the ?-pinene/benzene proportion. PMID:25464289

  6. Metal mixture modeling evaluation project: 3. Lessons learned and steps forward.

    PubMed

    Farley, Kevin J; Meyer, Joseph S

    2015-04-01

    A comparison of 4 metal mixture toxicity models (that were based on the biotic ligand model [BLM] and the Windermere humic aqueous model using the toxicity function [WHAM-FTOX ]) was presented in a previous paper. In the present study, a streamlined version of the 4 models was developed and applied to multiple data sets and test conditions to examine key assumptions and calibration strategies that are crucial in modeling metal mixture toxicity. Results show that 1) a single binding site on or in the organism was a useful and oftentimes sufficient framework for predicting metal toxicity; 2) a linear free energy relationship (LFER) for bidentate binding of metals and cations to the biotic ligand provided a good first estimate of binding coefficients; 3) although adjustments in metal binding coefficients or adjustments in chemical potency factors can both be used in model calibration for single-metal exposures, changing metal binding coefficients or chemical potency factors had different effects on model predictions for metal mixtures; and 4) selection of a mixture toxicity model (based on concentration addition or independent action) was important in predicting metal mixture toxicity. Moving forward, efforts should focus on reducing uncertainties in model calibration, including development of better methods to characterize metal binding to toxicologically active binding sites, conducting targeted exposure studies to advance the understanding of metal mixture toxicity, and further developing LFERs and other tools to help constrain the model calibration. PMID:25475765

  7. Toxicity of a complex mixture of atmospherically transported pesticides to Ceriodaphnia dubia.

    PubMed

    George, Tara K; Waite, Don; Liber, Karsten; Sproull, Jim

    2003-07-01

    The presence of several anthropogenic chemicals has been documented in the atmosphere of the Canadian prairies. The deposition of these chemicals as a mixture is of importance since little is known of the combined effects of these chemicals on aquatic organisms. This study was designed to evaluate the acute and chronic toxicity of a complex mixture of nine atmospherically transported pesticides to Ceriodaphnia dubia. The nine selected pesticides (bromoxynil, dicamba, 2,4-D, MCPA, triallate, trifluralin, pentachlorophenol, lindane, and 4,4'-DDT) were detected in appreciable quantities in dry atmospheric deposits. The concentration of each pesticide in the mixture was based on maximum measured daily dry deposition rates for central Canada, except for pentachlorophenol, which was estimated based on atmospheric concentrations. The 48-h LC50 estimate for C. dubia exposed to the pesticide mixture was 174.60 microg L(-1) (340 times the measured total dry deposition concentration). The estimated NOEC and LOEC for both survival and reproduction, as determined in the 7-d chronic toxicity test, were 51.3 (100 times) and 154 microg/L(-1) (300 times), respectively. A basic risk assessment, using the toxic unit approach, suggested that the toxicity of the pesticide mixture was mainly due to 4,4'-DDT. Overall, this atmospherically transported complex mixture of pesticides appears to pose a negligible toxicological risk to non-target aquatic invertebrates such as zooplankton. PMID:12841692

  8. Heterogeneous Batch Distillation Processes for Waste Solvent Recovery in Pharmaceutical Industry

    Microsoft Academic Search

    Ivonne Rodriguez-Donis; Vincent Gerbaud; Alien Arias-Barreto; Xavier Joulia

    2009-01-01

    A summary about our experiences in the introduction of heterogeneous entrainers in azeotropic and extractive batch distillation is presented in this work. Essential advantages of the application of heterogeneous entrainers are showed by rigorous simulation and experimental verification in a bench batch distillation column for separating several azeotropic mixtures such as acetonitrile — water, n hexane — ethyl acetate and

  9. A supercritical Rankine cycle using zeotropic mixture working fluids for the conversion of low-grade heat into power

    Microsoft Academic Search

    Huijuan Chen; D. Yogi Goswami; Muhammad M. Rahman; Elias K. Stefanakos

    2011-01-01

    A supercritical Rankine cycle using zeotropic mixture working fluids for the conversion of low-grade heat into power is proposed and analyzed in this paper. Unlike a conventional organic Rankine cycle, a supercritical Rankine cycle does not go through the two-phase region during the heating process. By adopting zeotropic mixtures as the working fluids, the condensation process also happens non-isothermally. Both

  10. Isobaric vapor–liquid equilibrium for binary mixtures of 2-methylpentane+ethanol and +2-methyl-2-propanol

    Microsoft Academic Search

    Antonio Aucejo; Sonia Loras; Rosa Muñoz; Luis Miguel Ordoñez

    1999-01-01

    Vapor–liquid equilibrium (VLE) data for the binary systems, 2-methylpentane+ethanol and 2-methylpentane+2-methyl-2-propanol (TBA), are reported at 101.3 kPa, including pure component vapor pressures. The systems deviate remarkably from ideal behaviour presenting one positive azeotrope. The activity coefficients and boiling points of the solutions were correlated with its composition by Wilson, UNIQUAC, NRTL, and Wisniak–Tamir equations.

  11. A constitutive theory of reacting electrolyte mixtures

    NASA Astrophysics Data System (ADS)

    Costa Reis, Martina; Wang, Yongqi; Bono Maurizio Sacchi Bassi, Adalberto

    2013-11-01

    A constitutive theory of reacting electrolyte mixtures is formulated. The intermolecular interactions among the constituents of the mixture are accounted for through additional freedom degrees to each constituent of the mixture. Balance equations for polar reacting continuum mixtures are accordingly formulated and a proper set of constitutive equations is derived with basis in the Müller-Liu formulation of the second law of thermodynamics. Moreover, the non-equilibrium and equilibrium responses of the reacting mixture are investigated in detail by emphasizing the inner and reactive structures of the medium. From the balance laws and constitutive relations, the effects of molecular structure of constituents upon the fluid flow are studied. It is also demonstrated that the local thermodynamic equilibrium state can be reached without imposing that the set of independent constitutive variables is time independent, neither spatially homogeneous nor null. The resulting constitutive relations presented throughout this work are of relevance to many practical applications, such as swelling of clays, developing of bio and polymeric membranes, and use of electrorheological fluids in industrial processes. A constitutive theory of reacting electrolyte mixtures is formulated. The intermolecular interactions among the constituents of the mixture are accounted for through additional freedom degrees to each constituent of the mixture. Balance equations for polar reacting continuum mixtures are accordingly formulated and a proper set of constitutive equations is derived with basis in the Müller-Liu formulation of the second law of thermodynamics. Moreover, the non-equilibrium and equilibrium responses of the reacting mixture are investigated in detail by emphasizing the inner and reactive structures of the medium. From the balance laws and constitutive relations, the effects of molecular structure of constituents upon the fluid flow are studied. It is also demonstrated that the local thermodynamic equilibrium state can be reached without imposing that the set of independent constitutive variables is time independent, neither spatially homogeneous nor null. The resulting constitutive relations presented throughout this work are of relevance to many practical applications, such as swelling of clays, developing of bio and polymeric membranes, and use of electrorheological fluids in industrial processes. The first author acknowledges financial support from National Counsel of Technological and Scientific Development (CNPq) and German Academic Exchange Service (DAAD).

  12. Use of electroluminescence of gas mixtures for optical data acquisition from wire chambers

    SciTech Connect

    Polyakov, V.A.; Rykalin, V.I.; Tskhadadze, E.G.

    1988-07-01

    The radiation spectra, electroluminescence light yields, and gas-amplification factors of mixtures of Ar and Ne with inorganic and organic admixtures in a wire chamber operating in the proportional and self-quenched streamer (SQS) modes are measured. Maximum light yields of 2 x 10/sup 7/ photons for mixtures of Ar + acetone + white spirit and 1.1 x 10/sup 7/ photons for Ar + CO/sub 2/ + ethanol + white spirit in the SQS mode are obtained. Three methods for optical data acquisition from wire chambers are tested. Best results are obtained when spectrum-shifting strips and fibers are placed behind the cathode planes of the chamber.

  13. Organic spintronics

    Microsoft Academic Search

    W. J. M. Naber; S. Faez; W. G. van der Wiel

    2007-01-01

    We review the emerging field of organic spintronics, where organic materials are applied as a medium to transport and control spin-polarized signals. The contacts for injecting and detecting spins are formed by ferromagnetic metals, oxides, or inorganic semiconductors. First, the basic concepts of spintronics and organic electronics are addressed, and phenomena which are in particular relevant for organic spintronics are

  14. Spectrophotometric and LC determination of two binary mixtures containing antihistamins

    Microsoft Academic Search

    Alaa El-Gindy; Samy Emara; Ahmed Mostafa

    2004-01-01

    Several methods are developed for the determination of two binary mixtures containing cyclizine hydrochloride with pyridoxine HCl (mixture (mix.) 1); and cinnarizine with piracetam (mix. 2). The resolution of the two binary mixtures has been accomplished by using numerical spectrophotometric methods as partial least squares (PLS-1) and principal component regression applied to UV spectra of the mixture and graphical spectrophotometric

  15. Mixture Models for Estimating Maximum Blood Flow Velocity

    E-print Network

    Marzban, Caren

    . Here, two generalizations are examined: 1) skewed gaussian and 2) non- gaussian mixture models. Both ultrasound data. The method was based on a gaussian mixture model for the distribution of blood flow. Mixture" blood flow velocity. But gaussian mixture models are restric- tive in that the distribution of blood

  16. Scalable Training of Mixture Models via Coresets Dan Feldman

    E-print Network

    Heaton, Thomas H.

    ? In this paper, we show how to construct coresets for mixtures of Gaussians and natural generalizations provide a good fit for the original data set. We show that, perhaps surprisingly, Gaussian mixtures admit consider the problem of training statistical mixture models, in particular mixtures of Gaussians and some

  17. CONTROLLED COMBUSTION OF LOW-QUALITY GAS MIXTURES

    Microsoft Academic Search

    Malinen Kaisu; Järvinen Mika; Saari Kari; Lampinen Markku; Fogelholm Carl-Johan; Riikonen Arto

    The objective of this work was to experimentally de termine the lowest levels of methane content in gas mixtures that would still en able controlled combustion using a commercial standard gas burner. A gas mixture is of low quality when it is uncertai n whether the mixture will ignite or maintain stable combustion. Such low-quality gas mixtures can typically include

  18. Mixture autoregressive hidden Markov models for speech signals

    Microsoft Academic Search

    Biing-Hwang Juang; LAWRENCE R. RABINER

    1985-01-01

    In this paper a signal modeling technique based upon finite mixture autoregressive probabilistic functions of Markov chains is developed and applied to the problem of speech recognition, particularly speaker-independent recognition of isolated digits. Two types of mixture probability densities are investigated: finite mixtures of Gaussian autoregressive densities (GAM) and nearest-neighbor partitioned finite mixtures of Gaussian autoregressive densities (PGAM). In the

  19. Interpreting simple STR mixtures using allele peak areas

    Microsoft Academic Search

    P. Gill; R. Sparkes; R. Pinchin; T. Clayton; J. Whitaker; J. Buckleton

    1998-01-01

    Although existing statistical models can interpret mixtures qualitatively based upon the alleles present, the use of automated sequencers opens the opportunity to take account of quantitative aspects embodied by the peak area. One step in understanding simple mixtures consisting of just two donors is to estimate the mixture ratio. This is relatively easy to do when four-allele mixtures are evident

  20. ADDITIVITY ASSESSMENT OF TRIHALOMETHANE MIXTURES BY PROPORTIONAL RESPONSE ADDITION

    EPA Science Inventory

    If additivity is known or assumed, the toxicity of a chemical mixture may be predicted from the dose response curves of the individual chemicals comprising the mixture. As single chemical data are abundant and mixture data sparse, mixture risk methods that utilize single chemical...

  1. Bounded asymmetrical Student's-t mixture model.

    PubMed

    Nguyen, Thanh Minh; Wu, Q M Jonathan

    2014-06-01

    The finite mixture model based on the Student's-t distribution, which is heavily tailed and more robust than the Gaussian mixture model (GMM), is a flexible and powerful tool to address many computer vision and pattern recognition problems. However, the Student's-t distribution is unbounded and symmetrical around its mean. In many applications, the observed data are digitalized and have bounded support. The distribution of the observed data usually has an asymmetric form. A new finite bounded asymmetrical Student's-t mixture model (BASMM), which includes the GMM and the Student's-t mixture model (SMM) as special cases, is presented in this paper. We propose an extension of the Student's-t distribution in this paper. This new distribution is sufficiently flexible to fit different shapes of observed data, such as non-Gaussian, nonsymmetric, and bounded support data. Another advantage of the proposed model is that each of its components can model the observed data with different bounded support regions. In order to estimate the model parameters, previous models represent the Student's-t distributions as an infinite mixture of scaled Gaussians. We propose an alternate approach in order to minimize the higher bound on the data negative log-likelihood function, and directly deal with the Student's-t distribution. As an application, our method has been applied to image segmentation with promising results. PMID:23893763

  2. Relativistic mixtures of charged and uncharged particles

    SciTech Connect

    Kremer, Gilberto M. [Departamento de Física, Universidade Federal do Paraná, Curitiba (Brazil)

    2014-01-14

    Mixtures of relativistic gases within the framework of Boltzmann equation are analyzed. Three systems are considered. The first one refers to a mixture of uncharged particles by using Grad’s moment method, where the relativistic mixture is characterized by the moments of the distribution functions: particle four-flows, energy-momentum tensors, and third-order moment tensors. In the second Fick’s law for a mixture of relativistic gases of non-disparate rest masses in a Schwarzschild metric are derived from an extension of Marle and McCormack model equations applied to a relativistic truncated Grad’s distribution function, where it is shown the dependence of the diffusion coefficient on the gravitational potential. The third one consists in the derivation of the relativistic laws of Ohm and Fourier for a binary mixtures of electrons with protons and electrons with photons subjected to external electromagnetic fields and in presence of gravitational fields by using the Anderson and Witting model of the Boltzmann equation.

  3. Synergy and other ineffective mixture risk definitions.

    SciTech Connect

    Hertzberg, R.; MacDonell, M.; Environmental Assessment

    2002-04-08

    A substantial effort has been spent over the past few decades to label toxicologic interaction outcomes as synergistic, antagonistic, or additive. Although useful in influencing the emotions of the public and the press, these labels have contributed fairly little to our understanding of joint toxic action. Part of the difficulty is that their underlying toxicological concepts are only defined for two chemical mixtures, while most environmental and occupational exposures are to mixtures of many more chemicals. Furthermore, the mathematical characterizations of synergism and antagonism are inextricably linked to the prevailing definition of 'no interaction,' instead of some intrinsic toxicological property. For example, the US EPA has selected dose addition as the no-interaction definition for mixture risk assessment, so that synergism would represent toxic effects that exceed those predicted from dose addition. For now, labels such as synergism are useful to regulatory agencies, both for qualitative indications of public health risk as well as numerical decision tools for mixture risk characterization. Efforts to quantify interaction designations for use in risk assessment formulas, however, are highly simplified and carry large uncertainties. Several research directions, such as pharmacokinetic measurements and models, and toxicogenomics, should promote significant improvements by providing multi-component data that will allow biologically based mathematical models of joint toxicity to replace these pairwise interaction labels in mixture risk assessment procedures.

  4. Permeation of chemical protective clothing by three binary solvent mixtures

    SciTech Connect

    Mickelsen, R.L.; Roder, M.M.; Berardinelli, S.P.

    1986-04-01

    An evaluation of glove materials against three different binary chemical mixtures selected from common industrial solvents was conducted. Changes in breakthrough time and permeation rate of the mixture components were evaluated as a function of the mixture composition. An increase in employee risk resulting from early mixture breakthrough time and enhanced mixture permeation rate over that of the pure chemicals was demonstrated. The permeation of a binary mixture through chemical protective clothing could not be predicted by the permeation results of the pure components. It is recommended that chemical protective clothing be tested for its permeation characteristics with the use of the chemical mixtures and conditions that reflect the work site exposure.

  5. The NACA mixture analyzer and its application to mixture-distribution measurement in flight

    NASA Technical Reports Server (NTRS)

    Gerrish, Harold C; Meem, J Lawrence, Jr; Scadron, Marvin D; Colnar, Anthony

    1947-01-01

    The NACA mixture analyzer was developed as a research instrument for the continuous indication of fuel-air ratios of aircraft engine installations throughout the range of engine operation. It has been evaluated by using it to measure the mixture distribution of a nine-cylinder radial aircraft engine in flight. The mixture distribution among the cylinders in flight was obtained at normal operating conditions for the engine at an altitude of 5000 feet. Some limited data was also obtained at an altitude of 20,000 feet. Results of these flight tests showed that the NACA mixture analyzer is a satisfactory and dependable instrument for continuous indication of the mixture in flight at all engine conditions regardless of altitude and temperature.

  6. Dynamics of binary phase separation in liquid He-3-He-4 mixtures

    NASA Technical Reports Server (NTRS)

    Hoffer, J. K.; Sinha, D. N.

    1986-01-01

    Binary phase-separation dynamics in liquid mixtures of He-3 and He-4 has been investigated near the tricritical point with laser-light scattering techniques. Rapid decompression of the mixtures results in quenches into the miscibility gap so that both the metastable and unstable (spinodal) regions can be probed. Quenches into the unstable region allowed measurements of the normalized dynamic structure factor S(k,t) that confirm the dynamical scaling hypotheses for spinodal decomposition. Measurements made for concentrations well away from the tricritical value show different behavior and suggest the presence of a spinodal boundary. Forward scattering intensities for shallow quenches probe nucleation phenomena and permit quantitative measurements of anomalous super-cooling as a function of quench rate. Comparisons with data in organic binary mixtures are given.

  7. Generalized competitive learning of gaussian mixture models.

    PubMed

    Lu, Zhiwu; Ip, Horace H S

    2009-08-01

    When fitting Gaussian mixtures to multivariate data, it is crucial to select the appropriate number of Gaussians, which is generally referred to as the model selection problem. Under regularization theory, we aim to solve this model selection problem through developing an entropy regularized likelihood (ERL) learning on Gaussian mixtures. We further present a gradient algorithm for this ERL learning. Through some theoretic analysis, we have shown a mechanism of generalized competitive learning that is inherent in the ERL learning, which can lead to automatic model selection on Gaussian mixtures and also make our ERL learning algorithm less sensitive to the initialization as compared to the standard expectation-maximization algorithm. The experiments on simulated data using our algorithm verified our theoretic analysis. Moreover, our ERL learning algorithm has been shown to outperform other competitive learning algorithms in the application of unsupervised image segmentation. PMID:19362913

  8. Ethane-xenon mixtures under shock conditions

    NASA Astrophysics Data System (ADS)

    Magyar, Rudolph J.; Root, Seth; Cochrane, Kyle; Mattsson, Thomas R.; Flicker, Dawn G.

    2015-04-01

    Mixtures of light elements with heavy elements are important in inertial confinement fusion. We explore the physics of molecular scale mixing through a validation study of equation of state (EOS) properties. Density functional theory molecular dynamics (DFT-MD) at elevated temperature and pressure is used to obtain the thermodynamic state properties of pure xenon, ethane, and various compressed mixture compositions along their principal Hugoniots. To validate these simulations, we have performed shock compression experiments using the Sandia Z-Machine. A bond tracking analysis correlates the sharp rise in the Hugoniot curve with the completion of dissociation in ethane. The DFT-based simulation results compare well with the experimental data along the principal Hugoniots and are used to provide insight into the dissociation and temperature along the Hugoniots as a function of mixture composition. Interestingly, we find that the compression ratio for complete dissociation is similar for several compositions suggesting a limiting compression for C-C bonded systems.

  9. Dry-Ice Bath Based on Ethylene Glycol Mixtures

    NASA Astrophysics Data System (ADS)

    Lee, Do W.; Jensen, Craig M.

    2000-05-01

    Bath mixtures of ethanol and ethylene glycol in dry ice produce sustainable constant temperatures over the range from -12 to -78 °C, which show a linear relationship between the bath temperature and the volume fraction of ethylene glycol. Our bath is less toxic than previously reported mixtures of ortho- and meta-xylene, and our mixture does not intractably solidify as will dry ice slurries of xylenes. Moreover, the cost of this mixture is less than that of the xylene mixtures.

  10. Differential viability of phosphoglucose isomerase allozyme genotypes of marine snails in nonionic detergent and crude oil-surfactant mixtures

    SciTech Connect

    Lavie, B.; Nevo, E.; Zoller, U.

    1984-10-01

    The effects of a nonionic detergent and of crude oil-detergent mixtures in aqueous solutions on the allozyme frequencies of phosphoglucose isomerase (Pgi) genotypes were tested in the Mediterranean marine gastropods Monodonta turbinata and M. turbiformis. Our results indicate differential survivorship of electrophoretical Pgi allozyme genotypes for both detergent alone and for crude oil-detergent mixtures. These results reflect the adaptive nature of some Pgi genotypes in these marine gastropods and seem inconsistent with the neutral theory of allozyme polymorphisms. Furthermore, these findings suggest that allozyme variants demonstrate a differential tolerance to these organic pollutants and can, therefore, be used as detectors of organic pollutants in the sea.

  11. Arc Lamp Dose Development Using Mixture Designs

    NASA Astrophysics Data System (ADS)

    Coffey, Tom

    2009-04-01

    The US Department of energy estimates that 25% of the commercial energy consumption and 12% of residential energy consumption is used for lighting in the US. The under-lying science of ceramic metal halide lamps continues to elude complete understanding. Because modeling efforts give an incomplete picture, ceramic metal halide lamp design is largely an experimental science. Mixture designs are a special family of designed experiments used to determine the correct proportions of the components in a multi-component blend. The use of a mixture design to determine the dose composition for a ceramic metal halide arc lamp will be presented.

  12. On Normal Variance-Mean Mixtures

    E-print Network

    Yu, Yaming

    2011-01-01

    Normal variance-mean mixtures encompass a large family of useful distributions such as the generalized hyperbolic distribution, which itself includes the Student t, Laplace, hyperbolic, normal inverse Gaussian, and variance gamma distributions as special cases. We study shape properties of normal variance-mean mixtures, in both the univariate and multivariate cases, and determine conditions for unimodality and log-concavity of the density functions. This leads to a short proof of the unimodality of all generalized hyperbolic densities. We also interpret such results in practical terms and discuss discrete analogues.

  13. A co-fermentation strategy to consume sugar mixtures effectively

    PubMed Central

    Eiteman, Mark A; Lee, Sarah A; Altman, Elliot

    2008-01-01

    We report a new approach for the simultaneous conversion of xylose and glucose sugar mixtures into products by fermentation. The process simultaneously uses two substrate-selective strains of Escherichia coli, one which is unable to consume glucose and one which is unable to consume xylose. The xylose-selective (glucose deficient) strain E. coli ZSC113 has mutations in the glk, ptsG and manZ genes while the glucose-selective (xylose deficient) strain E. coli ALS1008 has a mutation in the xylA gene. By combining these two strains in a single process, xylose and glucose are consumed more quickly than by a single-organism approach. Moreover, we demonstrate that the process is able to adapt to changing concentrations of these two sugars, and therefore holds promise for the conversion of variable sugar feed streams, such as lignocellulosic hydrolysates. PMID:18304345

  14. Simple finite mixture model to deconvolve excitation-emission matrices.

    NASA Astrophysics Data System (ADS)

    Butturini, Andrea

    2014-05-01

    Decomposition of EEMs is in important step in analysis of excitation-emission matrices (EEMs). This poster is based on a previous work (Butturini and Ejarque, Biogeosciences, 10, 5875-5887, doi:10.5194/bg-10-5875-2013, 2013) in which a simple mathematical algorithm that automatically deconvolves individual EEMs is described. A mixture model approach is adopted to decompose complex surfaces into asymmetric-Gaussian sub-peaks. The laplacian operator and the Nelder-Mead optimization algorithm are implemented to individuate and automatically locate potential peaks in the EEM landscape. The EEMs of dissolved organic matter samples collected in a Mediterranean river are used to describe the model application, and to illustrate a strategy that optimises the search for the optimal output.

  15. Roles of biomarkers in evaluating interactions among mixtures of lead, cadmium and arsenic

    SciTech Connect

    Wang Gensheng [Department of Experimental Radiation Oncology, U.T.M.D. Anderson Cancer Center, Houston, TX 77030 (United States)], E-mail: genwang@mdanderson.org; Fowler, Bruce A. [Division of Toxicology and Environmental Medicine, ATSDR, Atlanta, GA 30333 (United States)

    2008-11-15

    Human exposure to environmental chemicals is most correctly characterized as exposure to mixtures of these agents. The metals/metalloids, lead (Pb), cadmium (Cd), and arsenic (As), are among the leading toxic agents detected in the environment. Exposure to these elements, particularly at chronic low dose levels, is still a major public health concern. Concurrent exposure to Pb, Cd, or As may produce additive or synergistic interactions or even new effects that are not seen in single component exposures. Evaluating these interactions on a mechanistic basis is essential for risk assessment and management of metal/metalloid mixtures. This paper will review a number of individual studies that addressed interactions of these metals/metalloids in both experimental and human exposure studies with particular emphasis on biomarkers. In general, co-exposure to metal/metalloid mixtures produced more severe effects at both relatively high dose and low dose levels in a biomarker-specific manner. These effects were found to be mediated by dose, duration of exposure and genetic factors. While traditional endpoints, such as morphological changes and biochemical parameters for target organ toxicity, were effective measures for evaluating the toxicity of high dose metal/metalloid mixtures, biomarkers for oxidative stress, altered heme biosynthesis parameters, and stress proteins showed clear responses in evaluating toxicity of low dose metal/metalloid mixtures. Metallothionein, heat shock proteins, and glutathione are involved in regulating interactive effects of metal/metalloid mixtures at low dose levels. These findings suggest that further studies on interactions of these metal/metalloid mixtures utilizing biomarker endpoints are highly warranted.

  16. Leaching of Mixtures of Biochar and Fly Ash

    SciTech Connect

    Palumbo, Anthony Vito [ORNL] [ORNL; Porat, Iris [ORNL] [ORNL; Phillips, Jana Randolph [ORNL] [ORNL; Amonette, J. E. [Pacific Northwest National Laboratory (PNNL)] [Pacific Northwest National Laboratory (PNNL); Drake, Meghan M [ORNL] [ORNL; Brown, Steven D [ORNL] [ORNL; Schadt, Christopher Warren [ORNL] [ORNL

    2009-01-01

    Increasing atmospheric levels of greenhouse gases, especially CO2, and their effects on global temperature have led to interest in the possibility of carbon storage in terrestrial environments.2, 5, 6 Both the residual char from biomass pyrolysis7-9, 12 (biochar) and fly ash from coal combustion1, 13, 14 have the potential to significantly expand terrestrial sequestration options. Both biochar and fly ash also have potentially beneficial effects on soil properties. Fly ash has been shown to increase porosity, water-holding capacity, pH, conductivity, and dissolved SO42-, CO32-, Cl- and basic cations.10, 11, 16 Adding biochar to soil generally raises pH, increases total nitrogen and total phosphorous, encourages greater root development, improves cation exchange capacity and reduces available aluminum.3, 17 Combinations of these benefits likely lead to the observed increased yields for crops including corn and sugarcane.17 with biochar addition to soil. In addition, it has been found that soils with added biochar emit lower amounts of other greenhouse gases (methane and nitrous oxide) 8, 17 than do unammended soils. Biochar and fly ash amendments may be useful in promoting terrestrial carbon sequestration on currently underutilized and degraded lands. For example, about 1% of the US surface lands consist of previously mined lands or highway rights-of-way.18 Poorly managed lands could count for another 15% of US area. Biochar and fly ash amendments could increase productivity of these lands and increase carbon storage in the soil Previous results showed minimal leaching of organic carbon and metals from a variety of fly ashes.15 Here, we are examining the properties of mixtures of biochar, fly ash, and soil and evaluating leaching of organic carbon and metals from the mixtures.

  17. Mixtures of chemical pollutants at European legislation safety concentrations: how safe are they?

    PubMed

    Carvalho, Raquel N; Arukwe, Augustine; Ait-Aissa, Selim; Bado-Nilles, Anne; Balzamo, Stefania; Baun, Anders; Belkin, Shimshon; Blaha, Ludek; Brion, François; Conti, Daniela; Creusot, Nicolas; Essig, Yona; Ferrero, Valentina E V; Flander-Putrle, Vesna; Fürhacker, Maria; Grillari-Voglauer, Regina; Hogstrand, Christer; Jonáš, Adam; Kharlyngdoh, Joubert B; Loos, Robert; Lundebye, Anne-Katrine; Modig, Carina; Olsson, Per-Erik; Pillai, Smitha; Polak, Natasa; Potalivo, Monica; Sanchez, Wilfried; Schifferli, Andrea; Schirmer, Kristin; Sforzini, Susanna; Stürzenbaum, Stephen R; Søfteland, Liv; Turk, Valentina; Viarengo, Aldo; Werner, Inge; Yagur-Kroll, Sharon; Zounková, Radka; Lettieri, Teresa

    2014-09-01

    The risk posed by complex chemical mixtures in the environment to wildlife and humans is increasingly debated, but has been rarely tested under environmentally relevant scenarios. To address this issue, two mixtures of 14 or 19 substances of concern (pesticides, pharmaceuticals, heavy metals, polyaromatic hydrocarbons, a surfactant, and a plasticizer), each present at its safety limit concentration imposed by the European legislation, were prepared and tested for their toxic effects. The effects of the mixtures were assessed in 35 bioassays, based on 11 organisms representing different trophic levels. A consortium of 16 laboratories was involved in performing the bioassays. The mixtures elicited quantifiable toxic effects on some of the test systems employed, including i) changes in marine microbial composition, ii) microalgae toxicity, iii) immobilization in the crustacean Daphnia magna, iv) fish embryo toxicity, v) impaired frog embryo development, and vi) increased expression on oxidative stress-linked reporter genes. Estrogenic activity close to regulatory safety limit concentrations was uncovered by receptor-binding assays. The results highlight the need of precautionary actions on the assessment of chemical mixtures even in cases where individual toxicants are present at seemingly harmless concentrations. PMID:24958932

  18. Quantification of the joint effects of mixtures of hepatotoxic agents: evaluation of a theoretical model in mice

    SciTech Connect

    Shelton, D.W.; Weber, L.J.

    1981-10-01

    An approach previously developed for studying the effects of toxic mixtures on whole organism performances (i.e., growth, mortality) was evaluated to determine its applicability and limitations at the organ system level. The approach was tested by quantifying the hepatotoxic effects of carbon tetrachloride (CCl/sub 4/), monochlorobenzene (MCB), acetaminophen (ACET), and selected mixtures of these compounds in male albino CF-1 mice. Based upon parallel dose-response curves, concentration addition was predicted for the mixtures of both CCl/sub 4/ + MCB and CCl/sub 4/ + ACET. The actual dose-response relationship for each mixture was empirically determined and compared to the predicted curves. In the case of the CCl/sub 4/ + ACET mixture revealed a statistical difference between the observed and predicted curves. The joint effects for the mixture of CCl/sub 4/ + MCB is thus classified as concentration additive. The model proves to be adequate in predicting, classifying, and describing the joint effects of these hepatotoxicants.

  19. Tetramethylammonium hydroxide as a reagent for complex mixture analysis by negative ion electrospray ionization mass spectrometry.

    PubMed

    Lobodin, Vladislav V; Juyal, Priyanka; McKenna, Amy M; Rodgers, Ryan P; Marshall, Alan G

    2013-08-20

    Ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) enables the direct characterization of complex mixtures without prior fractionation. High mass resolution can distinguish peaks separated by as little as 1.1 mDa), and high mass accuracy enables assignment of elemental compositions in mixtures that contain tens of thousands of individual components (crude oil). Negative electrospray ionization (ESI) is particularly useful for the speciation of the most acidic petroleum components that are implicated in oil production and processing problems. Here, we replace conventional ammonium hydroxide by tetramethylammonium hydroxide (TMAH, a much stronger base, with higher solubility in toluene) to more uniformly deprotonate acidic components of complex mixtures by negative ESI FTICR MS. The detailed compositional analysis of four crude oils (light to heavy, from different geographical locations) reveals that TMAH reagent accesses 1.5-6 times as many elemental compositions, spanning a much wider range of chemical classes than does NH4OH. For example, TMAH reagent produces abundant negative electrosprayed ions from less acidic and neutral species that are in low abundance or absent with NH4OH reagent. More importantly, the increased compositional coverage of TMAH-modified solvent systems maintains, or even surpasses, the compositional information for the most acidic species. The method is not limited to petroleum-derived materials and could be applied to the analysis of dissolved organic matter, coal, lipids, and other naturally occurring compositionally complex organic mixtures. PMID:23919350

  20. A Colorful Solubility Exercise for Organic Chemistry

    ERIC Educational Resources Information Center

    Shugrue, Christopher R.; Mentzen, Hans H., II; Linton, Brian R.

    2015-01-01

    A discovery chemistry laboratory has been developed for the introductory organic chemistry student to investigate the concepts of polarity, miscibility, solubility, and density. The simple procedure takes advantage of the solubility of two colored dyes in a series of solvents or solvent mixtures, and the diffusion of colors can be easily…

  1. Performance characteristics of organic Rankine cycles

    Microsoft Academic Search

    J. P. Lamb

    1984-01-01

    The organic Rankine cycle is one of the most promising techniques for production of mechanical power from low temperature sources such as solar heated fluids, geothermal brines and industrial waste heat. A series of cycle performance calculations has been carried out for a broad range of working fluids including Refrigerant 12, isobutane, isopentane, propone, and toluene as well as mixtures

  2. Matching Organs

    MedlinePLUS

    ... hospitals and organ procurement organizations in a secure, real-time environment. Because UNet uses the Internet, it allows ... HONcode standard for trustworthy health information: verify here. Search only trustworthy HONcode health websites:

  3. Microwave heating of water-ethanol mixtures

    Microsoft Academic Search

    A. Paoli; A. Schiraldi

    1995-01-01

    The susceptibility of a given chemical compound shows to the microwave action can be described with the resulting heating rate, that depends on the distance from the irradiated surface, the extintion coefficient and heat capacity of the chemical compound considered.When a homogeneous mixture is subjected to microwave irradiation, the heating rate depends on the average values of the above parameters.

  4. Calculating Circulation Concentration of Zeotropic Refrigerant Mixtures

    Microsoft Academic Search

    J. Chen; H. Kruse

    1995-01-01

    The circulation concentration of a zeotropic refrigerant mixture may differ from the refrigerant bulk concentration in a vapor compression cycle. The difference, defined as “concentration shift,” is mainly caused by the differential holdup in two-phase regions and the differential solubility of the oil. In this paper the concentration shift caused by the differential holdup of the two-phase flow of liquid

  5. Theory of dynamic arrest in colloidal mixtures

    NASA Astrophysics Data System (ADS)

    Juárez-Maldonado, R.; Medina-Noyola, M.

    2008-05-01

    We present a first-principles theory of dynamic arrest in colloidal mixtures based on the multicomponent self-consistent generalized Langevin equation theory of colloid dynamics [M. A. Chávez-Rojo and M. Medina-Noyola, Phys. Rev. E 72, 031107 (2005); M. A. Chávez-Rojo and M. Medina-Noyola, Phys. Rev. E76, 039902 (2007)]. We illustrate its application with a description of dynamic arrest in two simple model colloidal mixtures: namely, hard-sphere and repulsive Yukawa binary mixtures. Our results include observation of the two patterns of dynamic arrest, one in which both species become simultaneously arrested and the other involving the sequential arrest of the two species. The latter case gives rise to mixed states in which one species is arrested while the other species remains mobile. We also derive the (”bifurcation” or fixed-point”) equations for the nonergodic parameters of the system, which takes the surprisingly simple form of a system of coupled equations for the localization length of the particles of each species. The solution of this system of equations indicates unambiguously which species is arrested (finite localization length) and which species remains ergodic (infinite localization length). As a result, we are able to draw the entire ergodic-nonergodic phase diagram of the binary hard-sphere mixture.

  6. Topic Analysis Using a Finite Mixture Model.

    ERIC Educational Resources Information Center

    Li, Hang; Yamanishi, Kenji

    2003-01-01

    Presents a single framework for conducting topic analysis that performs both topic identification and text segmentation. Key characteristics of the framework are: representing a topic by means of a cluster of words closely related to the topic; and employing a stochastic model, called a finite mixture model, to represent a word distribution within…

  7. Regularized Finite Mixture Models for Probability Trajectories

    ERIC Educational Resources Information Center

    Shedden, Kerby; Zucker, Robert A.

    2008-01-01

    Finite mixture models are widely used in the analysis of growth trajectory data to discover subgroups of individuals exhibiting similar patterns of behavior over time. In practice, trajectories are usually modeled as polynomials, which may fail to capture important features of the longitudinal pattern. Focusing on dichotomous response measures, we…

  8. Characterisation of stone matrix asphalt mixtures

    Microsoft Academic Search

    Laith Tashman; Brian Pearson

    2011-01-01

    This study applied conventional laboratory tests and advanced imaging techniques to experimentally verify the voids in coarse aggregate (VCA) method. Five stone matrix asphalt (SMA) mixtures designed to have different coarse aggregate skeletons were investigated to establish relationships between the VCA ratio, microstructure parameters and the mechanical response of SMA. X-ray CT and image analysis techniques were utilised to non-destructively

  9. Investigation into three-layered HMA mixtures

    Microsoft Academic Search

    Baoshan Huang; Guoqiang Li; Xiang Shu

    2006-01-01

    Hot-mix asphalt (HMA) mixtures consist of three phases: aggregate, asphalt binder (mastic) and air voids, of which the first two (aggregate and asphalt binder) provide the structure that withstands various kinds of loading.Due to the nature of high inhomogeneity between aggregate and asphalt binder, significant stress and strain concentration occurs at the interface between the two phases, which causes adverse

  10. Characterisation of stone matrix asphalt mixtures

    Microsoft Academic Search

    Laith Tashman; Brian Pearson

    2012-01-01

    This study applied conventional laboratory tests and advanced imaging techniques to experimentally verify the voids in coarse aggregate (VCA) method. Five stone matrix asphalt (SMA) mixtures designed to have different coarse aggregate skeletons were investigated to establish relationships between the VCA ratio, microstructure parameters and the mechanical response of SMA. X-ray CT and image analysis techniques were utilised to non-destructively

  11. Frontiers in thermoacoustic refrigeration and mixture separation

    E-print Network

    Frontiers in thermoacoustic refrigeration and mixture separation S. Backhaus1 , D. Geller2 , B a combustion-powered thermoacoustic natural gas liquefier, radioisotope and reactor-driven thermoacoustic engines for generating electrical power on spacecraft, and heat-driven thermoacoustic engines and engine

  12. The inverse Raman scattering in mixture

    Microsoft Academic Search

    P. Gadow; A. Lau; Ch. T. Thuy; H.-J. Weigmann; W. Werncke; K. Lenz; M. Pfeiffer

    1971-01-01

    We report here investigations of two-component mixtures by inverse Raman scattering. Concerning detectability best results are obtained using a model locked ruby laser and a ``one-cell arrangement''. Concentrations ranging from 1.0 to 0.005 mole\\/1 were detectable. Absorption lines are also observed in the fluorescence continuum of the dye cryptocyanine.

  13. Classification of Material Mixtures in Volume Data

    E-print Network

    Classification of Material Mixtures in Volume Data for Visualization and Modeling David H. Laidlaw Material classification is a key step in creating computer graphics models and images from volume data. We present a new algorithm for identifying the distribution of different material types in volu­ metric

  14. Classification of Material Mixtures in Volume Data

    E-print Network

    Classification of Material Mixtures in Volume Data for Visualization and Modeling David H. Laidlaw ¢¡¤£¦¥¨§©¤¥ Material classification is a key step in creating computer graphics models and images from volume data. We present a new algorithm for identifying the distribution of different material types in volu- metric

  15. Crystal Growth of Water Ethanol Mixture

    NASA Astrophysics Data System (ADS)

    Ohkubo, Hidetoshi; Matsumoto, Nakamichi; Ochiai, Jun-Ichi; Nakajima, Masahiro

    Water ethanol mixture has a liquidus line (or crystallizing line) and a solidus line (or melting line) that are separated, and therefore it can have both liquid and solid phases existing together. As a result, with advances in low temperature technology in recent days, water ethanol mixture is attracting more and more attention as an environment friendly coolant or as a thermal storage material. In this study, we investigated the mechanism of mushy crystal formation and the state of am ushy layer formed on ac ooling surface, with the objective of utilizing water ethanol mixture as ac oolant or at hermal energy storage material. Two types of experiments were done in this work in order to study the mechanisms of crystal formation and growth. In one experiment, we studied the mechanism of crystal formation within a minute droplet of water ethanol mixture, and in the other, the mechanism of the crystal growth in the mushy layer formed in a liquid pool in contact with a cooling surface.

  16. A review of semiparametric mixture models

    Microsoft Academic Search

    Bruce G. Lindsay; Mary L. Lesperance

    1995-01-01

    The literature on semiparametric mixture models has flourished over the last decade, both in applied and theoretical journals. In this paper, we review examples of important areas of application, and summarize some of the recent developments in maximum likelihood theory, including inference for the mixing distribution and the structural parameters. The theory and applications developed to date suggest that semiparametric

  17. Methods and systems for deacidizing gaseous mixtures

    DOEpatents

    Hu, Liang

    2010-05-18

    An improved process for deacidizing a gaseous mixture using phase enhanced gas-liquid absorption is described. The process utilizes a multiphasic absorbent that absorbs an acid gas at increased rate and leads to reduced overall energy costs for the deacidizing operation.

  18. Infinite Mixtures of Gaussian Process Experts

    Microsoft Academic Search

    Carl Edward Rasmussen; Zoubin Ghahramani

    2001-01-01

    We present an extension to the Mixture of Experts (ME) model, where the individual experts are Gaussian Process (GP) regression models. Us- ing an input-dependent adaptation of the Dirichlet Process, we imple- ment a gating network for an infinite number of Experts. Inference in this model may be done efficiently using a Markov Chain relying on Gibbs sampling. The model

  19. Dirichlet Process Mixtures of Generalized Linear Models

    Microsoft Academic Search

    Lauren A. Hannah; David M. Blei; Warren B. Powell

    2010-01-01

    We propose Dirichlet Process mixtures of Generalized Linear Models (DP-GLMs), a new method of nonparametric regression that accommodates continuous and categorical inputs, models a response variable locally by a generalized linear model. We give conditions for the existence and asymptotic unbiasedness of the DP-GLM regression mean function estimate; we then give a practical example for when those conditions hold. We

  20. The Generalized Gaussian Mixture Model Using ICA

    Microsoft Academic Search

    Te-won Lee; Michael S. Lewicki

    2000-01-01

    An extension of the Gaussian mixture model is presentedusing Independent Component Analysis (ICA)and the generalized Gaussian density model. The mixturemodel assumes that the observed data can be categorizedinto mutually exclusive classes whose componentsare generated by a linear combination of independentsources. The source densities are modeled bygeneralized Gaussians (Box and Tiao, 1973) that providea general method for modeling non-Gaussian statisticalstructure of

  1. Nonmonotonic Generalization Bias of Gaussian Mixture Models

    Microsoft Academic Search

    Shotaro Akaho; Hilbert J. Kappen

    2000-01-01

    Most theories of generalization performanceof learning tell us that the generalization bias, which is definedas the difference between an training error and angeneralization error, increases proportionally to the numberof modifiable parameters in average. The present paper,however, reports the case that the generalization biasof a Gaussian mixture model does not increase even if thesuperficial effective number of parameters increases, wherethe number

  2. Evaporation of Liquid Hydrocarbon Mixtures on Titan

    NASA Astrophysics Data System (ADS)

    Luspay-Kuti, Adrienn; Chevrier, V. F.; Rivera-Valentin, E. G.; Singh, S.; Roe, L. A.; Wagner, A.

    2013-10-01

    Besides Earth, Titan is the only other known planetary body with proven stable liquids on its surface. The hydrological cycle of these liquid hydrocarbon mixtures is critical in understanding Titan’s atmosphere and surface features. Evaporation of liquid surface bodies has been indirectly observed as shoreline changes from measurements by Cassini ISS and RADAR (Hayes et al. 2011, Icarus 211, 655-671; Turtle et al. 2011, Science 18, 1414-1417.), but the long seasons of Saturn strongly limit the time span of these observations and their validity over the course of an entire Titan year. Using a novel Titan simulation chamber, the evaporation rate of liquid methane and dissolved nitrogen mixture under Titan surface conditions was derived (Luspay-Kuti et al. 2012, GRL 39, L23203), which is especially applicable to low latitude transient liquids. Polar lakes, though, are expected to be composed of a variety of hydrocarbons, primarily a mixture of ethane and methane (e.g. Cordier et al. 2009, ApJL 707, L128-L131). Here we performed laboratory simulations of ethane-methane mixtures with varying mole fraction under conditions suitable for the polar regions of Titan. We will discuss results specifically addressing the evaporation behavior as the solution becomes increasingly ethane dominated, providing quantitative values for the evaporation rate at every step. These laboratory results are relevant to polar lakes, such as Ontario Lacus, and can shed light on their stability.

  3. Separation of binary protein mixtures by ultrafiltration

    Microsoft Academic Search

    Eiji Iritani; Yasuhito Mukai; Toshiro Murase

    1997-01-01

    Ultrafiltration of aqueous solutions of mixtures of bovine serum albumin(BSA) and egg white lysozyme was conducted using membranes which were almost completely retentive for BSA, but permeable for lysozyme, in order to investigate the factors influencing the filtration rate and the lysozyme rejection. The experimental data obtained in this study clearly demonstrate that the electrostatic interactions between dissimilar molecules may

  4. A Mixture Model for Clustering Ensembles

    Microsoft Academic Search

    Alexander P. Topchy; Anil K. Jain; William F. Punch

    2004-01-01

    Clustering ensembles have emerged as a powerful method for improving both the robustness and the stability of unsupervised classification solutions. However, finding a consensus clustering from multiple partitions is a difficult problem that can be approached from graph-based, combinatorial or statistical perspectives. We offer a probabilistic model of consensus using a finite mixture of multinomial distributions in a space of

  5. Audio source separation of convolutive mixtures

    Microsoft Academic Search

    Nikolaos Mitianoudis; Michael E. Davies

    2003-01-01

    The problem of separation of audio sources recorded in a real world situation is well established in modern literature. A method to solve this problem is Blind Source Separation (BSS) using Independent Compo- nent Analysis (ICA). The recording environment is usually modelled as convolutive. Previous research on ICA of instan- taneous mixtures provided solid background for the sepa- ration of

  6. TOXICOLOGY OF COMPLEX MIXTURES OF INDOOR AIR

    EPA Science Inventory

    This review focuses on strategies for assessing the toxicology of indoor air pollutant mixtures. hese strategies are illustrated by reviewing the current problems and approaches to the toxicology of indoor air pollutants from three indoor source categories which make a major cont...

  7. Theoretical Thermodynamics of Mixtures at High Pressures

    NASA Technical Reports Server (NTRS)

    Hubbard, W. B.

    1985-01-01

    The development of an understanding of the chemistry of mixtures of metallic hydrogen and abundant, higher-z material such as oxygen, carbon, etc., is important for understanding of fundamental processes of energy release, differentiation, and development of atmospheric abundances in the Jovian planets. It provides a significant theoretical base for the interpretation of atmospheric elemental abundances to be provided by atmospheric entry probes in coming years. Significant differences are found when non-perturbative approaches such as Thomas-Fermi-Dirac (TFD) theory are used. Mapping of the phase diagrams of such binary mixtures in the pressure range from approx. 10 Mbar to approx. 1000 Mbar, using results from three-dimensional TFD calculations is undertaken. Derivation of a general and flexible thermodynamic model for such binary mixtures in the relevant pressure range was facilitated by the following breakthrough: there exists an accurate nd fairly simple thermodynamic representation of a liquid two-component plasma (TCP) in which the Helmholtz free energy is represented as a suitable linear combination of terms dependent only on density and terms which depend only on the ion coupling parameter. It is found that the crystal energies of mixtures of H-He, H-C, and H-O can be satisfactorily reproduced by the same type of model, except that an effective, density-dependent ionic charge must be used in place of the actual total ionic charge.

  8. Selection of antifreeze moistener for ramming mixtures

    Microsoft Academic Search

    L. A. Babkina; Yu. A. Pirogov; P. Ya. Pustovar; L. N. Soloshenko; N. S. Shevtsov; A. D. Efimenko; R. N. Ishchenko; L. A. Inyushina

    1994-01-01

    It has been established that orthophosphoric acid, which is used as an antifreeze moistener in ramming mixtures for sand-blasting ramming of walls of steel-teeming ladles, can be replaced by an aqueous solution of sodium acetate, a waste product of the Kaluzhskii Integrated Works of Synthetic Aromatic Substances.

  9. Inert gas: Vapor mixtures in thermoacoustics

    Microsoft Academic Search

    William Victor Slaton

    2001-01-01

    An analytic solution of sound propagation in wet-walled tubes with a temperature gradient will be presented. The tube contains an inert gas-vapor mixture with a thin layer of condensed vapor coating the tube wall. The vapor phase condenses and evaporates from this layer during an acoustic cycle. This phased evaporation and condensation modifies traditional energy density and wave number equations.

  10. Continuous Crystallization of Urea-Water Mixture

    NASA Astrophysics Data System (ADS)

    Hokamura, Taku; Ohkubo, Hidetoshi; Watanabe, Satoshi; Seki, Mitsuo; Murakoshi, Hiromichi

    Ice slurries have been used as environmentally-friendly secondary refrigerants. In addition to such ice slurries, aqueous solutions in slurry-state have also been put to practical use at temperatures below 0 oC. Urea-water mixture is a multi-component substance that has a eutectic point. If we can form a two-phase fluid substance by the liquid-solid phases at the eutectic point, it can be used as a fluid latent heat storage material, which will maintain the secondary refrigerant in a heat exchanger at constant temperature. In the present study, we propose a urea-water mixture as a novel functional thermal fluid that can be used as a fluid latent heat material. To demonstrate its feasibility, we first measured the latent heat and density of a urea-water mixture, and then used a counter-flow double tube heat exchanger to produce a liquid-solid two-phase flow of the urea-water mixture. This work demonstrates that it is possible to make a fluid latent heat storage material continuously from an aqueous solution at the eutectic point by flowing it through a double tube heat exchanger equipped with a stirrer.

  11. Mixtures of liquid-crystalline polymers

    Microsoft Academic Search

    P. Maïssa; P. Sixou

    1989-01-01

    A density-functional expansion method is used to derive the free energy of a polymer mixture. The expression obtained includes the entropy of mixing, the entropy of configuration of the chains and the interactions (both isotropic and anisotropic ones). The chains are modelled as interacting elastic lines (bend curvature). The method is very general, and we only focus our attention on

  12. Electronic energy transfer in rare gas mixtures

    Microsoft Academic Search

    A. Szoke; Y. Binur; R. Shuker; E. Zamir

    1974-01-01

    In a spectroscopic study carried out in this laboratory a new energy transfer mechanism from a noble gas molecule to an atom was identified. This transfer process is similar to the Penning ionization in the sense that it populates energy levels of a guest atom selectively within a certain range. A mixture of Ar:Xe was studied. This report discusses these

  13. Learning Mixtures of Ranking Models Pranjal Awasthi

    E-print Network

    Blum, Avrim

    Learning Mixtures of Ranking Models Pranjal Awasthi Princeton University pawashti probabilistic models for ranking data in a heteroge- neous population. The specific problem we study is learning algorithm is a novel use of tensor decomposition techniques to learn the top-k prefix in both the rankings

  14. Mixture segregation by an inertial cavitation bubble

    Microsoft Academic Search

    R. Grossier; O. Louisnard; Y. Vargas

    2007-01-01

    Pressure diffusion is a mass diffusion process forced by pressure gradients. It has the ability to segregate two species of a mixture, driving the densest species toward high pressure zones, but requires very large pressure gradients to become noticeable. An inertial cavitation bubble develops large pressure gradients in its vicinity, especially as the bubble rebounds at the end of its

  15. Segregation in granular binary mixtures: Thermal diffusion

    Microsoft Academic Search

    V. Garzó

    2006-01-01

    A solution of the inelastic Boltzmann equation that applies for strong dissipation and takes into account non-equipartition of energy is used to derive an explicit expression for the thermal diffusion factor. This parameter provides a criterion for segregation that involves all the parameters of the granular binary mixture (composition, masses, sizes, and coefficients of restitution). The present work is consistent

  16. Mixtures of Large Margin Nearest Neighbor Classifiers

    E-print Network

    Alpaydýn, Ethem

    that learns a global Mahalanobis distance. We propose a mixture of such classifiers where a gating function divides the input space into regions and a separate distance function is learned in each region in a lower structure as given by a covariance matrix S, one should use the Mahalanobis distance: DM = (xi - xj) M

  17. Instabilities in fermions and BEC mixtures

    Microsoft Academic Search

    Shan-Wen Tsai; Ryan M. Kalas; Eddy Timmermans

    2010-01-01

    We study instabilities in a mixture of interacting fermionic and bosonic ultra-cold atoms. We focus on BCS transitions of the fermions that can be generated from attractive interactions mediated by bosons that are in a BEC phase. We study the p-wave instability [1] for indistinguishable (single spin) fermions in detail, taking into account the dynamical part of the mediated interaction.

  18. Unbalanced fermion mixtures on an optical lattice

    Microsoft Academic Search

    Chuntai Shi; Tun Wang; Shan-Wen Tsai

    2011-01-01

    We study a two component fermion mixture on a square lattice. We describe such system by a Hubbard model wherein there is only on-site interaction between fermions of different species. Such a model can be realized by loading ultra cold fermions onto an optical lattice and by tuning the interaction strength via Feshbach resonance. We investigate the phase diagram of

  19. HEALTH RISK ASSESSMENT OF CHEMICAL MIXTURES

    EPA Science Inventory

    The implementation of Superfund requires a methodology for estimating health risk from multi-chemical contamination at ambient levels. Most often, the chemical composition of these mixtures is poorly characterized, exposure data are uncertain and toxicologic data on the known com...

  20. RELATIVE TOXICITY OF AIR POLLUTION MIXTURES

    EPA Science Inventory

    The proposed study will differentiate the health effects of components of multi-pollutant exposure mixtures. We expect to add to our understanding of the exposure- response relationship, the interaction between particulate matter and photochemical gases, and the extent to whic...

  1. Chemical Mixtures and Children’s Health

    PubMed Central

    Henn, Birgit Claus; Coull, Brent A.; Wright, Robert O.

    2014-01-01

    Purpose of Review Humans are routinely exposed to multiple chemicals simultaneously or sequentially. There is evidence that the toxicity of individual chemicals may depend on the presence of other chemicals. Studies on chemical mixtures are limited, however, due to lack of sufficient exposure data, limited statistical power, and difficulty in the interpretation of multi-dimensional interactions. This review summarizes the recent literature examining chemical mixtures and pediatric health outcomes, with an emphasis on metal mixtures. Recent Findings Several studies report significant interactions between metals in relation to pediatric health outcomes. Two prospective studies found interactive effects of early life lead and manganese exposures on cognition. In two different cohorts, interactions between lead and cadmium exposures were reported on reproductive hormone levels and on neurodevelopment. Effects of lead exposure on impulsive behavior and cognition were modified by mercury exposure in studies from Canada and Denmark. However, there is little consistency related to exposure indicators and statistical approaches for evaluating interaction. Summary Several studies suggest that metals interact to cause health effects that are different from exposure to each metal alone. Despite the nearly infinite number of possible chemical combinations, mixtures research represents real life exposure scenarios and warrants more attention, particularly in the context of uniquely vulnerable children. PMID:24535499

  2. Binary mixture flammability characteristics for hazard assessment

    E-print Network

    Vidal Vazquez, Migvia del C.

    2005-11-01

    ......................................................................42 4.1.4 Water ? 2-Propanol ......................................................................44 4.2 Flammable Mixtures ................................................................................46 4.2.1 Chlorobenzene - Aniline... ..............................................................46 4.2.2 Ethanol ? Aniline .........................................................................48 4.2.3 Octane ? Methanol .......................................................................50 4.2.4 Octane ? Ethanol...

  3. Thermodiffusion in binary and ternary nonpolar hydrocarbon + alcohol mixtures

    NASA Astrophysics Data System (ADS)

    Eslamian, Morteza; Saghir, M. Ziad

    2012-12-01

    Thermodiffusion in complex mixtures, such as associating, molten metal, and polymer mixtures is difficult to model usually owing to the occurrence of a sign change in the thermodiffusion coefficient when the mixture concentration and temperature change. A mixture comprised of a nonpolar hydrocarbon and an alcohol is a complex and highly non-ideal mixture. In this paper an existing binary non-equilibrium thermodynamics model (Eslamian and Saghir, Physical Review E 80, 061201, 2009) developed for aqueous mixtures of alcohols is examined against the experimental data of binary nonpolar hydrocarbon and alcohol mixtures. For ternary mixtures, non-equilibrium thermodynamic expressions developed by the authors for aqueous mixtures of alcohols (Eslamian and Saghir, Canadian Journal of Chemical Engineering, DOI 10.1002/cjce.20581) is used to predict thermodiffusion coefficients of ternary nonpolar hydrocarbon and alcohol mixtures. The rationale behind the sign change is elucidated and attributed to an anomalous change in the molecular structure and therefore viscosity of such mixtures. Model predictions of thermodiffusion coefficients of binary mixtures predict a sign change consistent with the experimental data although the model is still too primitive to capture all structural complexities. For instance, in the methanol-benzene mixture where the model predictions are poorest, the viscosity data show that when concentration varies, the mixture's molecular structure experiences a severe change twice, the first major change leading to a maximum in the thermodiffusion coefficient, whereas the second change causes a sign change.

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

    PubMed

    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. PMID:20680632

  5. Analysis of guest binary mixtures by tert-butylcalix[6]arene using host memory of previously bound guests.

    PubMed

    Safina, Goulnaz D; Ziganshin, Marat A; Gubaidullin, Aidar T; Gorbatchuk, Valery V

    2013-02-28

    A new principle of quantitative and qualitative analysis of binary organic mixtures is offered, which is based on an ability of calixarene receptor for specific polymorphic transitions related to the composition of the analyzed guest mixture. The ability of tert-butylcalix[6]arene to remember selectively some guests bound from headspace both of pure liquids and their binary mixtures is used. The image of guest mixture remains written in metastable polymorphs of host after partial or complete guest elimination from clathrates. The memory was read using differential scanning calorimetry as the enthalpy of exothermic polymorphic transition of host collapse. This enthalpy monotonously changes with the variation of guests' ratio in mixture, unlike the enthalpies of endothermic pseudopolymorphic transitions of guest release. So, the composition of volatile binary mixture can be estimated using only one receptor and only one its parameter even in absence of preferential binding from a binary mixture of guests. This is an example of a genuine molecular recognition. PMID:23329280

  6. Joint effects of heavy metal binary mixtures on seed germination, root and shoot growth, bacterial bioluminescence, and gene mutation.

    PubMed

    Kong, In Chul

    2013-05-01

    This investigation was to assess the joint effects of metal binary mixtures on seed germination, root and shoot growth, bacterial bioluminescence, and gene mutation based on the one toxic unit (1 TU) approach. Different sensitivities and orders of toxicity of metal mixtures were observed among the bioassays. In general, mostly additive or antagonistic effects were observed, while almost no synergistic effects by the binary metal mixtures in all bioassays. Therefore, the combined effects of heavy metals in the different bioassays were difficult to generalize since they were dependent on both chemical type and the organism used in each bioassay. However, these results indicate that a battery of bioassays with mixture chemicals as opposed to just a single assay with single metal is a better strategy for the bioassessment of environmental pollutants. PMID:24218818

  7. The development and application of the chemical mixture methodology in analysis of potential health impacts from airborne release in emergencies

    SciTech Connect

    Yu, Xiao-Ying; Petrocchi, Achille J.; Craig, Douglas K.; Glantz, Clifford S.; Trott, Donna M.; Ciolek, John T.; Lu, Po-Yung; Bond, Jayne-Anne; Tuccinardi, Thomas E.; Bouslaugh, Philip R.

    2010-07-15

    The Chemical Mixture Methodology (CMM) is used for emergency response and safety planning by the U.S. Department of Energy, its contractors, and other private and public sector organizations. The CMM estimates potential health impacts on individuals and their ability to take protective actions as a result of exposure to airborne chemical mixtures. They are based on the concentration of each chemical in the mixture at a designated receptor location, the protective action criteria (PAC) providing chemical-specific exposure limit values, and the health code numbers (HCNs) that identify the target organ groupings that may be impacted by exposure to each chemical in a mixture. The CMM has been significantly improved since its introduction more than 10 years ago. Major enhancements involve the expansion of the number of HCNs from 44 to 60 and inclusion of updated PAC values based on an improved development methodology and updates in the data used to derive the PAC values. Comparisons between the 1999 and 2009 versions of the CMM show potentially substantial changes in the assessment results for selected sets of chemical mixtures. In particular, the toxic mode hazard indices (HIs) and target organ HIs are based on more refined acute HCNs, thereby improving the quality of chemical consequence assessment, emergency planning, and emergency response decision making. Seven hypothetical chemical storage and processing scenarios are used to demonstrate how the CMM is applied in emergency planning and hazard assessment.

  8. Laminar Flame Speeds of Moist Syngas Mixtures

    SciTech Connect

    Das, A. K.; Kumar, K.; Zhang, Z.; Sung, C. J.

    2011-01-01

    This work experimentally investigates the effect of the presence of water vapor on the laminar flame speeds of moist syngas/air mixtures using the counterflow twin-flame configuration. The experimental results presented here are for fuel lean syngas mixtures with molar percentage of hydrogen in the hydrogen and carbon monoxide mixture varying from 5% to 100%, for an unburned mixture temperature of 323 K, and under atmospheric pressure. At a given equivalence ratio, the effect of varying amount of water vapor addition on the measured laminar flame speed is demonstrated. The experimental laminar flame speeds are also compared with computed values using chemical kinetic mechanisms reported in the literature. It is found that laminar flame speed varies non-monotonically with addition of water for the carbon monoxide rich mixtures. It first increases with increasing amount of water addition, reaches a maximum value, and then decreases. An integrated reaction path analysis is further conducted to understand the controlling mechanism responsible for the non-monotonic variation in laminar flame speed due to water addition. On the other hand, for higher values of H{sub 2}/CO ratio the laminar flame speed monotonically decreases with increasing water addition. It is shown that the competition between the chemical and thermal effects of water addition leads to the observed response. Furthermore, reaction rate sensitivity analysis as well as binary diffusion coefficient sensitivity analysis are conducted to identify the possible sources of discrepancy between the experimental and predicted values. The sensitivity results indicate that the reaction rate constant of H{sub 2} + OH = H{sub 2}O + H is worth revisiting and refinement of binary diffusion coefficient data of N{sub 2}–H{sub 2}O, N{sub 2}–H{sub 2}, and H{sub 2}–H{sub 2}O pairs can be considered.

  9. Laminar flame speeds of moist syngas mixtures

    SciTech Connect

    Das, Apurba K. [Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, OH 44106 (United States); Kumar, Kamal; Sung, Chih-Jen [Department of Mechanical Engineering, University of Connecticut, Storrs, CT 06269 (United States)

    2011-02-15

    This work experimentally investigates the effect of the presence of water vapor on the laminar flame speeds of moist syngas/air mixtures using the counterflow twin-flame configuration. The experimental results presented here are for fuel lean syngas mixtures with molar percentage of hydrogen in the hydrogen and carbon monoxide mixture varying from 5% to 100%, for an unburned mixture temperature of 323 K, and under atmospheric pressure. At a given equivalence ratio, the effect of varying amount of water vapor addition on the measured laminar flame speed is demonstrated. The experimental laminar flame speeds are also compared with computed values using chemical kinetic mechanisms reported in the literature. It is found that laminar flame speed varies non-monotonically with addition of water for the carbon monoxide rich mixtures. It first increases with increasing amount of water addition, reaches a maximum value, and then decreases. An integrated reaction path analysis is further conducted to understand the controlling mechanism responsible for the non-monotonic variation in laminar flame speed due to water addition. On the other hand, for higher values of H{sub 2}/CO ratio the laminar flame speed monotonically decreases with increasing water addition. It is shown that the competition between the chemical and thermal effects of water addition leads to the observed response. Furthermore, reaction rate sensitivity analysis as well as binary diffusion coefficient sensitivity analysis are conducted to identify the possible sources of discrepancy between the experimental and predicted values. The sensitivity results indicate that the reaction rate constant of H{sub 2}+OH = H{sub 2}O+H is worth revisiting and refinement of binary diffusion coefficient data of N{sub 2}-H{sub 2}O, N{sub 2}-H{sub 2}, and H{sub 2}-H{sub 2}O pairs can be considered. (author)

  10. Energy and exergy analysis of an efficient organic Rankine cycle for low temperature power generation

    Microsoft Academic Search

    S. M. Sami

    2008-01-01

    This paper presents and discusses the performance of an advanced Organic Rankine Cycle (ORC) using a heated chemical instead of steam as found in the typical Rankine Cycle. Chemicals used are the new quaternary refrigerant mixtures that are environmentally-friendly and have efficient thermodynamic properties at low and medium waste heat temperatures compared to other organic and non-organic fluids.This mixture boils

  11. Control of an azeotropic distillation process to acetonitrile production

    Microsoft Academic Search

    Ruiz Andrea Ruiz; Beltrán Nelson Borda; Leguizamón R. Alexander; R. Javier; L. Guevara; D. Ivan; C. Gil

    2011-01-01

    The goal of this work is to evaluate and to simulate an alternative way to produce acetonitrile by means of extractive distillation. This chemical substance is used in pharmaceutics, solvents, antibiotics, vitamin and insulin production, among others. The high demand of this product during several years ago has created the necessity of increasing 5% the industrial production. Therefore, it is

  12. Trajectory mixture density networks with multiple mixtures for acoustic-articulatory inversion 

    E-print Network

    Richmond, Korin

    We have previously proposed a trajectory model which is based on a mixture density network (MDN) trained with target variables augmented with dynamic features together with an algorithm for estimating maximum likelihood trajectories which respects...

  13. Laboratory evaluation of crumb rubber asphalt concrete mixtures using the concepts of SMA mixtures 

    E-print Network

    Rebala, Somasekhar Reddy

    1994-01-01

    the potential to significantly improve the resistance to fatigue and thermal cracking characteristics of asphalt concrete mixtures. The wet method appears to yield better performance regardless of the rubber particle size. Fine rubber would improve the fatigue...

  14. Organ History

    NSDL National Science Digital Library

    Cook, James H.

    Developed and maintained by Professor James H. Cook at Birmingham - Southern College, this site is an online tutorial that offers an interesting and interactive perspective of that king of all instruments, the organ. The site is divided into three main sections: The Organ and How it Works, Organ History, and Geographical Tour. In the first section, visitors are taken through a basic description of an organ, which then continues into a discussion of the various parts of an organ, such as the keyboards, consoles, pipes, chests, cases, and chambers. The history section begins with the invention of what is commonly understood to be the first organ, the ktseibios, built by a Greek engineer working in the third century BCE. The final section takes visitors on a chronological tour of the organ and its development throughout a number of countries, including England, France, Germany, Italy, and the United States.

  15. Treatment of a mixture of three pesticides by photo- and electro-Fenton processes

    Microsoft Academic Search

    Aida Kesraoui Abdessalem; Nizar Bellakhal; Nihal Oturan; Mohamed Dachraoui; Mehmet A. Oturan

    2010-01-01

    In the present work, a comparative study of a mixture of three pesticides (chlortoluron, carbofuran and bentazon) has been investigated by advanced oxidation processes such as photo-Fenton and electro-Fenton. These processes are based on the in situ production of hydroxyl radical, a highly strong oxidant, which allows the degradation of organic pollutants until their mineralization into CO2 and H2O. For

  16. Toxicity of mixtures of nephrotoxicants with similar or dissimilar mode of action

    Microsoft Academic Search

    D. Jonker; R. A. Woutersen; V. J. Feron

    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 through different modes of action, were administered simultaneously at their individual lowest-observed-nephrotoxic-effect level (LONEL), no-observed-nephrotoxic-effect level (NONEL) and

  17. Treatment of Benzene and n-Hexane Mixtures in Trickle-Bed Air Biofilters

    Microsoft Academic Search

    Ashraf Aly Hassan; George A. Sorial

    2011-01-01

    Trickle-bed air biofilters (TBABs) are suitable for treatment of hydrophilic volatile organic compounds, but they pose a challenge for hydrophobic compounds. Three laboratory-scale TBABs were used for the treatment of an airstream contaminated with different ratios of n-hexane and benzene mixtures. The ratios studied were 1:1, 2:1, and 1:3 n-hexane:benzene by volume. Each TBAB was operated at a pH of

  18. Modified Anopore™ hybrid membranes for the microfiltration of cellulose acid hydrolysis mixtures

    Microsoft Academic Search

    Yong-Hong Zhao; Daniel F. Shantz

    2011-01-01

    Three classes of nonfouling substances, poly[poly(ethylene glycol) methyl ether methacrylate] (POEM), poly(sulfobetaine methacrylate) (PSBMA), and perfluoroalkyl tagged poly(ethylene glycol) surfactants (fPEG) were covalently tethered onto the surface of Anopore™ membranes (nominal pore size 0.2?m) to form a series of organic–inorganic hybrid membranes. These membranes were then used for the microfiltration of cellulose acid hydrolysis mixtures. Flux recoveries of over 80%

  19. Model-based learning using a mixture of mixtures of Gaussian and uniform distributions.

    PubMed

    Browne, Ryan P; McNicholas, Paul D; Sparling, Matthew D

    2012-04-01

    We introduce a mixture model whereby each mixture component is itself a mixture of a multivariate Gaussian distribution and a multivariate uniform distribution. Although this model could be used for model-based clustering (model-based unsupervised learning) or model-based classification (model-based semi-supervised learning), we focus on the more general model-based classification framework. In this setting, we fit our mixture models to data where some of the observations have known group memberships and the goal is to predict the memberships of observations with unknown labels. We also present a density estimation example. A generalized expectation-maximization algorithm is used to estimate the parameters and thereby give classifications in this mixture of mixtures model. To simplify the model and the associated parameter estimation, we suggest holding some parameters fixed-this leads to the introduction of more parsimonious models. A simulation study is performed to illustrate how the model allows for bursts of probability and locally higher tails. Two further simulation studies illustrate how the model performs on data simulated from multivariate Gaussian distributions and on data from multivariate t-distributions. This novel approach is also applied to real data and the performance of our approach under the various restrictions is discussed. PMID:22383342

  20. Parental exposure to natural mixtures of POPs reduced embryo production and altered gene transcription in zebrafish embryos.

    PubMed

    Lyche, Jan L; Grze?, Irena M; Karlsson, Camilla; Nourizadeh-Lillabadi, Rasoul; Berg, Vidar; Kristoffersen, Anja B; Skåre, Janneche U; Alestrøm, Peter; Ropstad, Erik

    2013-01-15

    Determination of toxicity of complex mixtures has been proposed to be one of the most important challenges for modern toxicology. In this study we performed genome wide transcriptome profiling to assess potential toxicant induced changes in gene regulation in zebrafish embryos following parental exposure to two natural mixtures of persistent organic pollutants (POPs). The mixtures used were extracted from burbot (Lota lota) liver originating from two lakes (Lake Mjøsa and Lake Losna) belonging to the same freshwater system in Norway. The dominating groups of contaminants were polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane metabolites (DDTs). Because both mixtures used in the present study induced similar effects, it is likely that the same toxicants are involved. The Mjøsa mixture contains high levels of PBDEs while this group of pollutants is low in the Losna mixture. However, both mixtures contain substantial concentrations of PCB and DDT suggesting these contaminants as the predominant contributors to the toxicity observed. The observed effects included phenotypic traits, like embryo production and survival, and gene transcription changes corresponding with disease and biological functions such as cancer, reproductive system disease, cardiovascular disease, lipid and protein metabolism, small molecule biochemistry and cell cycle. The changes in gene transcription included genes regulated by HNF4A, insulin, LH, FSH and NF-?B which are known to be central regulators of endocrine signaling, metabolism, metabolic homeostasis, immune functions, cancer development and reproduction. The results suggest that relative low concentrations of the natural mixtures of POPs used in the present study might pose a threat to wild freshwater fish living in the lakes from which the POPs mixtures originated. PMID:23063069

  1. Effect on marine sediment nitrogen fluxes caused by organic matter enrichment with varying organic carbon structure and nitrogen content

    Microsoft Academic Search

    Ingela Dahllöf; Ida-Maja Karle

    2005-01-01

    Enrichments with five types of organic carbon, differing in nitrogen content and type of organic carbon, were made to a marine sediment in order to study effects on nitrogen fluxes. The enrichments used were Ulva lactuca, Ascophyllum nodosum, Zostera marina, Ceratium spp., lignin, and mixtures of U. lactuca and A. nodosum. Fluxes of ammonium, nitrate, and phosphate were measured in

  2. Scale Mixture Models with Applications to Bayesian Inference

    NASA Astrophysics Data System (ADS)

    Qin, Zhaohui S.; Damien, Paul; Walker, Stephen

    2003-11-01

    Scale mixtures of uniform distributions are used to model non-normal data in time series and econometrics in a Bayesian framework. Heteroscedastic and skewed data models are also tackled using scale mixture of uniform distributions.

  3. BIOASSAY OF COMPLEX MIXTURES OF INDOOR AIR POLLUTANTS

    EPA Science Inventory

    Indoor air pollution is a complex mixture of chemicals originating from outdoor air and indoor sources. oxicology studies of these mixtures are limited by difficulties in obtaining indoor air samples or appropriately simulated exposures. he concentration of pollutants from indoor...

  4. Separation of zirconium and hafnium by solvent extraction using mixture of TBP and Cyanex 923

    NASA Astrophysics Data System (ADS)

    Taghizadeh, M.; Ghanadi, M.; Zolfonoun, E.

    2011-05-01

    In this study, a new Zr/Hf separation procedure by solvent extraction is proposed. The method is based on using the mixture of TBP and Cyanex 923 as extractant in the organic phase. Several parameters including; TBP/Cyanex 923 volume ratio, extractant concentration in the organic phase, nitric acid and NaNO 3 concentration in aqueous phase have been investigated. The results demonstrate better condition respect to traditional TBP/HNO 3 process. Lower required acid concentration and more zirconium extraction are some advantages of the new separation process.

  5. Process to prepare stable trifluorostyrene containing compounds grafted to base polymers using a solvent/water mixture

    DOEpatents

    Roelofs, Mark Gerrit; Yang, Zhen-Yu; Han, Amy Qi

    2010-06-15

    A fluorinated ion exchange polymer is prepared by grafting at least one grafting monomer derived from trifluorostyrene on to at least one base polymer in a organic solvent/water mixture. These ion exchange polymers are useful in preparing catalyst coated membranes and membrane electrode assemblies used in fuel cells.

  6. Toxicokinetic interactions and survival of Hyalella azteca exposed to binary mixtures of chlorpyrifos, dieldrin, and methyl mercury

    Microsoft Academic Search

    Jeffery A Steevens; William H Benson

    2001-01-01

    Chemical mixture interactions of chlorpyrifos, dieldrin, and methyl mercury were evaluated in Hyalellaazteca. Survival of adult and juvenile organisms was evaluated following exposure to individual chemicals and in binary combinations. Binary interactions of the model chemicals on survival of adult and juvenile H.azteca were evaluated by concentration–response curve analysis as additive, synergistic, antagonistic, or independent. Chlorpyrifos and methyl mercury interacted

  7. Environmentally Realistic Mixtures of the Five Regulated Haloacetic Acids Exhibit Concentration-Dependent Departures from Dose Additivity

    EPA Science Inventory

    Disinfection of water decreases waterborne disease. Disinfection byproducts (DBPs) are formed by the reaction of oxidizing disinfectants with inorganic and organic materials in the source water. The U.S. EPA regulates five haloacetic acid (HAA) DBPs as a mixture. The objective ...

  8. NMRI Measurements of Flow of Granular Mixtures

    NASA Technical Reports Server (NTRS)

    Nakagawa, Masami; Waggoner, R. Allen; Fukushima, Eiichi

    1996-01-01

    We investigate complex 3D behavior of granular mixtures in shaking and shearing devices. NMRI can non-invasively measure concentration, velocity, and velocity fluctuations of flows of suitable particles. We investigate origins of wall-shear induced convection flow of single component particles by measuring the flow and fluctuating motion of particles near rough boundaries. We also investigate if a mixture of different size particles segregate into their own species under the influence of external shaking and shearing disturbances. These non-invasive measurements will reveal true nature of convecting flow properties and wall disturbance. For experiments in a reduced gravity environment, we will design a light weight NMR imager. The proof of principle development will prepare for the construction of a complete spaceborne system to perform experiments in space.

  9. Embedded Electronic Nose for VOC Mixture Analysis

    SciTech Connect

    Botre, B.; Gharpure, D.; Shaligram, A. [Department of Electronic Science, University of Pune, Pune: 411007 (India)

    2009-05-23

    This paper details the work done towards a low cost, small size, portable embedded electronic nose (e-nose) and its application for analysis of different VOC mixtures. The sensor array is composed of commercially available metal oxide semiconductor sensors by Figaro. The embedded E-nose consists of an ADuC831 and has an RS 232 interface for Desktop PC for higher level data collection and NN training. The ESP tool with database facility and multilayer perceptron neural network (MLP NN) is employed to interface the embedded hardware and to process the electronic nose signals before being classified. The use of embedded e-nose for the quantification of VOCs in mixtures is investigated.

  10. Hydraulic Transport of Ice-Water Mixtures

    NASA Astrophysics Data System (ADS)

    Fujita, Toshihiko

    When an ice thermal storage system is introduced into a district cooling system,the hydraulic ice transport system must have an advantage over a conventional water transport system in saving pipe sizes and pumping powers. Referring to the literature providing direct information on the hydraulic transport of ice-water mixtures,the author comments on the following subjects : •Definitions of an ice packing factor. • The capacity of heat transported with ice-water mixtures. • District distribution system. • Flow patterns in ice-water two-phase flow in straight pipes. • General expressions for pressure losses in solid-liquid two-phase flow. • The characteristics of pressure losses in ice-water two-phase flow. •Choking phenomena in channels.

  11. Dusty Plasma Structures in Gas Mixtures

    SciTech Connect

    Popova, D. V.; Antipov, S. N.; Petrov, O. F.; Fortov, V. E. [Joint Institute for High Temperatures, Russian Academy of Sciences, Izhorskaya Str. 13/19, build 2, 125412 Moscow (Russian Federation); Maiorov, S. A. [A. M. Prokhorov General Physics Institute, Russian Academy of Sciences, Vavilov Str. 38, 119991 Moscow (Russian Federation)

    2008-09-07

    The possibility of attainment of large Mach numbers is analyzed for the case of heavy ions drifting in a light gas. Under conditions of typical experiments with dust structures in plasmas, the use of the mixture of light and heavy gases is shown to make it possible to suppress the ion heating in the electric field and to form supersonic flows characterized by large Mach numbers. The drift of krypton ions in helium is considered as an example. Experiments with dc glow discharge at 1-10% of Kr show that the transition to the discharge in mixture leads to increase of interaction anisotropy and reinforcement of coupling of dust particles in the direction of ion drift. On the other hand, under certain conditions the phenomenon of abnormal 'heating' of dust particles was observed when the particles can obtain high kinetic energy which is several orders of magnitude higher than typical.

  12. UV sensors based on liquid crystals mixtures

    NASA Astrophysics Data System (ADS)

    Chanishvili, Andro; Petriashvili, Gia; Chilaya, Guram; Barberi, Riccardo; De Santo, Maria P.; Matranga, Mario A.; Ciuchi, F.

    2006-04-01

    The Erythemal Response Spectrum is a scientific expression that describes the sensitivity of the skin to the ultraviolet radiation. The skin sensitivity strongly depends on the UV wavelength: a long exposition to UV radiation causes erythema once a threshold dose has been exceeded. In the past years several devices have been developed in order to monitor the UV exposure, most of them are based on inorganic materials that are able to mimic the human skin behaviour under UV radiation. We present a new device based on liquid crystals technology. The sensor is based on a liquid crystalline mixture that absorbs photons at UV wavelength and emits them at a longer one. This system presents several innovative features: the absorption range of the mixture can be varied to be sensitive to different wavelengths, the luminescence intensity can be tuned, the system can be implemented on flexible devices.

  13. Excess compressibility in binary liquid mixtures.

    PubMed

    Aliotta, F; Gapi?ski, J; Pochylski, M; Ponterio, R C; Saija, F; Salvato, G

    2007-06-14

    Brillouin scattering experiments have been carried out on some mixtures of molecular liquids. From the measurement of the hypersonic velocities we have evaluated the adiabatic compressibility as a function of the volume fraction. We show how the quadratic form of the excess compressibility dependence on the solute volume fraction can be derived by simple statistical effects and does not imply any interaction among the components of the system other than excluded volume effects. This idea is supported by the comparison of the experimental results with a well-established prototype model, consisting of a binary mixture of hard spheres with a nonadditive interaction potential. This naive model turns out to be able to produce a very wide spectrum of structural and thermodynamic features depending on values of its parameters. An attempt has made to understand what kind of structural information can be gained through the analysis of the volume fraction dependence of the compressibility. PMID:17581064

  14. Mixture segregation by an inertial cavitation bubble.

    PubMed

    Grossier, R; Louisnard, O; Vargas, Y

    2007-04-01

    Pressure diffusion is a mass diffusion process forced by pressure gradients. It has the ability to segregate two species of a mixture, driving the densest species toward high pressure zones, but requires very large pressure gradients to become noticeable. An inertial cavitation bubble develops large pressure gradients in its vicinity, especially as the bubble rebounds at the end of its collapse, and it is therefore expected that a liquid mixture surrounding such a bubble would become segregated. Theory developed in an earlier paper shows that this is indeed the case for sufficiently large molecules or nano-particles. The main theoretical results are recalled and a possible implication of this segregation phenomenon on the well-known cavitation-enhanced crystals nucleation is proposed. PMID:17208505

  15. Spark ignition of hydrogen-air mixture

    NASA Astrophysics Data System (ADS)

    Ono, Ryo; Oda, Tetsuji

    2008-12-01

    The electrostatic ignition of hydrogen-air mixture is investigated. First, the minimum ignition energy (MIE) of the hydrogen-air mixture is measured using a capacitance spark discharge. The influences of the spark gap length, humidity, and the spark pulse duration on the MIE are studied. It is shown that the MIE is approximately constant when the relative humidity increases from 0% to 90% at room temperature, and that the MIE is approximately constant when the spark duration is varied from 5 ns to 1 ms. Next, the density of OH radicals and gas temperature in an incipient spark-ignited hydrogen(50%)-air flame are measured using laser-induced predissociation fluorescence (LIPF). The time evolutions of the OH density and the gas temperature are measured from 3 ?s to 200 ?s after ignition.

  16. Mixture Hidden Markov Models in Finance Research

    NASA Astrophysics Data System (ADS)

    Dias, José G.; Vermunt, Jeroen K.; Ramos, Sofia

    Finite mixture models have proven to be a powerful framework whenever unobserved heterogeneity cannot be ignored. We introduce in finance research the Mixture Hidden Markov Model (MHMM) that takes into account time and space heterogeneity simultaneously. This approach is flexible in the sense that it can deal with the specific features of financial time series data, such as asymmetry, kurtosis, and unobserved heterogeneity. This methodology is applied to model simultaneously 12 time series of Asian stock markets indexes. Because we selected a heterogeneous sample of countries including both developed and emerging countries, we expect that heterogeneity in market returns due to country idiosyncrasies will show up in the results. The best fitting model was the one with two clusters at country level with different dynamics between the two regimes.

  17. Finite Mixtures of Generalized Linear Regression Models

    Microsoft Academic Search

    Bettina Grün; Friedrich Leisch

    Finite mixture models have now been used for more than hundred years (Newcomb (1886), Pearson (1894)). They are a very popular\\u000a statistical modeling technique given that they constitute a flexible and-easily extensible model class for (1) approximating\\u000a general distribution functions in a semi-parametric way and (2) accounting for unobserved heterogeneity. The number of applications\\u000a has tremendously increased in the last

  18. Evaluation of mixtures efficiency in refrigerating systems

    Microsoft Academic Search

    A. Stegou-Sagia; N. Paignigiannis

    2005-01-01

    The use of many common refrigerants is under restriction or phase out because of their high ODP (ozone depletion potential) or GWP (global warming potential). The regulations on environmentally acceptable substances are different from country to country and are subject to frequent updates. In our article, the following mixtures are under consideration: R-401B, R-401C, R-402A, R-404A, R-406A, R-408A, R-409A, R-410A,

  19. Deformation of debris-ice mixtures

    NASA Astrophysics Data System (ADS)

    Moore, Peter L.

    2014-09-01

    Mixtures of rock debris and ice are common in high-latitude and high-altitude environments and are thought to be widespread elsewhere in our solar system. In the form of permafrost soils, glaciers, and rock glaciers, these debris-ice mixtures are often not static but slide and creep, generating many of the landforms and landscapes associated with the cryosphere. In this review, a broad range of field observations, theory, and experimental work relevant to the mechanical interactions between ice and rock debris are evaluated, with emphasis on the temperature and stress regimes common in terrestrial surface and near-surface environments. The first-order variables governing the deformation of debris-ice mixtures in these environments are debris concentration, particle size, temperature, solute concentration (salinity), and stress. A key observation from prior studies, consistent with expectations, is that debris-ice mixtures are usually more resistant to deformation at low temperatures than their pure end-member components. However, at temperatures closer to melting, the growth of unfrozen water films at ice-particle interfaces begins to reduce the strengthening effect and can even lead to profound weakening. Using existing quantitative relationships from theoretical and experimental work in permafrost engineering, ice mechanics, and glaciology combined with theory adapted from metallurgy and materials science, a simple constitutive framework is assembled that is capable of capturing most of the observed dynamics. This framework highlights the competition between the role of debris in impeding ice creep and the mitigating effects of unfrozen water at debris-ice interfaces.

  20. Tracking concept drifting with Gaussian mixture model

    Microsoft Academic Search

    Jun Wu; Xian-Sheng Hua; Bo Zhang

    2005-01-01

    This paper mainly addresses the issue of semantic concept drifting in temporal sequences, such as video streams, over an extended period of time. Gaussian Mixture Model (GMM) is applied to model the distribution of under-investigating data, which are supposed to arrive or be generated in batches over time. The up-to-date classifier, which tracks the drifting concept, is directly built on

  1. Dirichlet Process Mixtures of Generalized Linear Models

    Microsoft Academic Search

    Lauren A. Hannah; David M. Blei; Warren B. Powell

    2010-01-01

    We propose Dirichlet Process mixtures of Generalized Linear Models (DP-GLM),\\u000aa new method of nonparametric regression that accommodates continuous and\\u000acategorical inputs, and responses that can be modeled by a generalized linear\\u000amodel. We prove conditions for the asymptotic unbiasedness of the DP-GLM\\u000aregression mean function estimate. We also give examples for when those\\u000aconditions hold, including models for compactly

  2. Conformal Solution Theory: Hard-Sphere Mixtures

    Microsoft Academic Search

    Douglas Henderson; Peter J. Leonard

    1971-01-01

    Conformal solution theory is examined. It is suggested that most difficulties associated with previous applications of this theory arise from the use of concentration-independent reference fluids. For the particular case of a hard-sphere mixture, it is shown that if the reference fluid is chosen so as to make the first-order term in the theory vanish, good results are obtained.

  3. On Theories for Reacting Immiscible Mixtures

    SciTech Connect

    Drumheller, D.S.

    1998-11-05

    On some small scale each constituent of an immiscible mixture occupies a separate region of space. Given sufficient time and computing power, we could solve the continuum field equations and boundary conditions for this het erogenous system. This usually represents an enormously difficult task that is well beyond today's computational ca- pabilities. Mixture theories approximate this complex heterogeneous formulation with a set of field equations for an equivalent homoge- neous mat erial. In this work, we compare the theory for immiscible mixtures by Drumheller and Bedford with the theory of Passman, Nunziato, and Walsh. We describe the conditions under which these theories reduce to an equivalent formulation, and we also investigate the differences in their microinertial descriptions. Two variables play special roles in both theories. They are t he true material density and the volume fraction. Here we use a kinematical approach based on two new variables-t he true deformation gradient and the distention gradient. We show how the true deformation gra- dient is connected to the true material density and, in the absence of chemical reactions, the volume fraction is the inverse of the deter- minant of the distention gradient. However, when chemical reactions occur, the distention gradient and the volume fraction are not directly connected. We ako present a mixture model for a granuIar expIosive. This model is based upon the work of Baer and Nunziato, but our theory differs from their work in that we Present a three-dimension-al rnodd, `.. ` - - we cast the constitutive postulates in terms of the distention gradient rather than the volume fraction, and we incorporate elastic-plastic effects into the constitutive description of the solid granules.

  4. Shear viscosity of hadronic gas mixtures

    E-print Network

    K. Itakura; O. Morimatsu; H. Otomo

    2008-05-12

    We investigate the effects of baryon chemical potential \\mu on the shear viscosity coefficient \\eta and the viscosity to entropy density ratio \\eta/s of a pion-nucleon gas mixture. We find that \\eta is an increasing function of T and \\mu, while the ratio \\eta/s turns to a decreasing function in a wide region of T-\\mu plane. In the kinematical region we studied, the smallest value of \\eta/s is about 0.3.

  5. Adsorptive separation of propylene-propane mixtures

    Microsoft Academic Search

    H. Jaervelin; James R. Fair

    1993-01-01

    The separation of propylene-propane mixtures is of great commercial importance and is carried out by fractional distillation. It is claimed to be the most energy-intensive distillation practiced in the United States. The purpose of this paper is to describe experimental work that suggests a practical alternative to distillation for separating the C[sub 3] hydrocarbons: adsorption. As studied, the process involves

  6. PVT measurements for five natural gas mixtures 

    E-print Network

    Simon, Philip Parayil

    1991-01-01

    OF FIGURES . V11 LIST OF TABLES INTRODUCTION . EXPERIMENT Method Apparatus Data Analysis Sample 10 RESULTS AND DISCUSSIONS 12 CONCLUSIONS 26 LITERATURE CITED 27 APPENDIX A: THE COOLING SYSTEM 29 APPENDIX B: VOLUMETRIC DATA . . 35 TABLE... OF CONTENTS (Continued) Page APPENDIX C: VOLUMETRIC DATA FROM PREVIOUS WORK 47 APPENDIX D 53 VITA 54 LIST OF FIGURES Page Figure 1. Schematic of the Burnett apparatus. Figure 2. Compressibility factors for the Amarillo gas mixture. Figure 3...

  7. Flocculation settling characteristics of mud: sand mixtures

    Microsoft Academic Search

    Andrew J. Manning; John V. Baugh; Jeremy R. Spearman; Richard J. S. Whitehouse

    2010-01-01

    When natural muds become mixed with sandy sediments in estuaries, it has a direct effect on the flocculation process and resultant\\u000a sediment transport regime. Much research has been completed on the erosion and consolidation of mud\\/sand mixtures, but very\\u000a little is known quantitatively about how mixed sediments interact whilst in suspension, particularly in terms of flocculation.\\u000a This paper presents the

  8. Noble gas mixture hollow cathode lasers

    Microsoft Academic Search

    M. Jánossy; L. Csillag; Z. Donkó; K. Rózsa

    1993-01-01

    A review of noble gas mixture ion lasers operating cw in hollow cathode discharges is given. The basic properties of hollow\\u000a cathode discharges and the main principles of tube construction are described. For the He?Kr, He?Ar and He?Ne?Xe systems laser\\u000a transitions, excitation mechanisms, operation of the lasers and questions of lasers for practical use are discussed. The single\\u000a frequency operation

  9. Phase behaviour of colloid-polymer mixtures

    Microsoft Academic Search

    W. C. K. Poon; S. M. Ilett; P. N. Pusey

    1994-01-01

    Summary  We review the phase behaviour of mixtures of colloids and non-adsorbing polymers. The exclusion of polymer molecules from\\u000a overlapping «depletion zones» between two neighbouring colloidal particles results in an unbalanced osmotic pressure pushing\\u000a the particles together. This depletion potential is separately tunable in range and depth. Theory predicts that the resulting\\u000a phase behaviour is sensitive to ?=r\\u000a g\\/R, the ratio

  10. The structure of colloid-polymer mixtures

    E-print Network

    A. A. Louis; R. Finken; J-P. Hansen

    1999-04-15

    We investigate the structure of colloid-polymer mixtures by calculating the structure factors for the Asakura-Oosawa model in the PY approximation. We discuss the role of potential range, polymer concentration and polymer-polymer interactions on the colloid-colloid structure. Our results compare reasonably well with the recent experiments of Moussa\\"{i}d et. al. for small wavenumber $k$, but we find that the Hansen-Verlet freezing criterion is violated when the liquid phase becomes marginal.

  11. Segregation in granular binary mixtures: Thermal diffusion

    E-print Network

    Vicente Garzo

    2006-06-27

    A recent solution of the inelastic Boltzmann equation that applies for strong dissipation and takes into account non-equipartition of energy is used to derive an explicit expression for the thermal diffusion factor. This parameter provides a criterion for segregation that involves all the parameters of the granular binary mixture (composition, masses, sizes, and coefficients of restitution). The present work is consistent with recent experimental results and extends previous results obtained in the intruder limit case.

  12. Analysis of exponential decay curves of mixtures

    E-print Network

    McGaughey, Robert Lee

    1967-01-01

    . Tommy Cobb who kept me on the straight and narrow during those first few trying weeks, and to Richard "Hoot" Gibson for his help with LP/90. TABLE OF CONTENTS Acknowledgments List of Tables CHAPTER Page lil Introduction III IV Linear... INTRODUCTION The object of this research was to determine the efficiency and accuracy of a method of analyzing exponential decay curves of radio- active mixtures by applying linear programming solutions to Prony's method. This research is an extension of a...

  13. digestive mixture by 2H NMR

    Microsoft Academic Search

    Philip W. Westerman

    H nuclear magnetic resonance (NMR) spectra were obtained at 30.87 MHz for 8% (w\\/v) aqueous disper- sions of mixtures of bile salts (MBS), mixed intestinal lipids (MIL; myristic acid, monomyristoylglycerol, dimyristoylphos- phatidylcholine = 5:1:1), and cholesterol, in which a single lipid component is selectively 2H-labeled. Using the observa- tion that the time-averaged quadrupole splitting of a C2H3 group varies according

  14. Liquid class predictor for liquid handling of complex mixtures

    DOEpatents

    Seglke, Brent W. (San Ramon, CA); Lekin, Timothy P. (Livermore, CA)

    2008-12-09

    A method of establishing liquid classes of complex mixtures for liquid handling equipment. The mixtures are composed of components and the equipment has equipment parameters. The first step comprises preparing a response curve for the components. The next step comprises using the response curve to prepare a response indicator for the mixtures. The next step comprises deriving a model that relates the components and the mixtures to establish the liquid classes.

  15. A new phonetic tied-mixture model for efficient decoding

    Microsoft Academic Search

    Akinobu Lee; Tatsuya Kawahara; Kazuya Takeda; Kiyohiro Shikano

    2000-01-01

    A phonetic tied-mixture (PTM) model for efficient large vocabulary continuous speech recognition is presented. It is synthesized from context-independent phone models with 64 mixture components per state by assigning different mixture weights according to the shared states of triphones. Mixtures are then re-estimated for optimization. The model achieves a word error rate of 7.0% with a 20000-word dictation of newspaper

  16. Environmental Organizations

    NSDL National Science Digital Library

    This online reference list provides links to nine local and national environmental organizations that have Web sites rich in valuable biodiversity information. Where possible, it includes the following information for each: details about the organization's mission, knowledge base, and activities; the type of support offered, including educational materials, resource libraries, and classes/workshops; and mailing address and contact information. In addition, links to four Web directories are provided, which in turn have links to dozens of other organizations.

  17. Lethal body burdens of chlorophenols and mixtures of chlorophenols in an oligochaete worm, Lumbriculus variegatus

    SciTech Connect

    Kukkonen, J. [Univ. of Joensuu (Finland). Dept. of Biology

    1995-12-31

    The lethal body burdens (LBB) of a few chlorophenol congeners were measured in the oligochaete worm, Lumbriculus variegatus. LBB is defined as the concentration of the compound in the organism on molar basis to cause a death. Groups of 40 organisms were exposed to different chlorophenol concentrations in artificial soft freshwater to achieve differential mortality. Exposure times were either 24 hours or 48 hours. Besides exposures with individual congener, mixtures of chlorophenols were also tested. After each exposure, the surviving organisms were collected and the body burden of chlorophenols were measured by GC with electron capture detection. Only the surviving organisms were analyzed, because dead worms started to decay rather quickly. The analyzed tissue concentrations were actually lower than in surviving organisms. The trichlorophenols and pentachlorophenol have a LBB of 0.4--0.7 {micro}mol/g wet weight. The 2,6-dichlorophenol has a slightly higher LBB of 1.0--1.6 {micro}mol/g wet weight. The LBB of chlorophenol mixtures (two congeners at a time) were of the same, on molar basis, as individual congeners demonstrating fully additive toxicity. The lethal body burdens of 2,4,5-trichlorophenol and pentachlorophenol in Lumbriculus variegatus were the same for these water-only exposures as previously reported for these compounds in two different sediments. The use of lethal body burden approach in sediment toxicology is further discussed.

  18. Negative Binomial Process Count and Mixture Modeling.

    PubMed

    Zhou, Mingyuan; Carin, Lawrence

    2013-10-17

    The seemingly disjoint problems of count and mixture modeling are united under the negative binomial (NB) process. A gamma process is employed to model the rate measure of a Poisson process, whose normalization provides a random probability measure for mixture modeling and whose marginalization leads to a NB process for count modeling. A draw from the NB process consists of a Poisson distributed finite number of distinct atoms, each of which is associated with a logarithmic distributed number of data samples. We reveal relationships between various count- and mixture-modeling distributions distributions, and construct a Poisson-logarithmic bivariate distribution that connects the NB and Chinese restaurant table distributions. Fundamental properties of the models are developed, and we derive efficient Bayesian inference. It is shown that with augmentation and normalization, the NB process and gamma-NB process can be reduced to the Dirichlet process and hierarchical Dirichlet process, respectively. These relationships highlight theoretical, structural and computational advantages of the NB process. A variety of NB processes, including the beta-geometric, beta-NB, marked-beta-NB, marked-gamma-NB and zero-inflated-NB processes, with distinct sharing mechanisms, are also constructed. These models are applied to topic modeling, with connections made to existing algorithms under Poisson factor analysis. Example results show the importance of inferring both the NB dispersion and probability parameters. PMID:24144977

  19. Separation of gas mixtures by thermoacoustic waves.

    SciTech Connect

    Swift, G. W. (Gregory W.); Geller, D. A. (Drew A.)

    2001-01-01

    Imposing sound on a binary gas mixture in a duct separates the two gases along the acoustic-propagation axis. Mole-fraction differences as large as 10% and separation fluxes as high as 0.001 M-squared c, where M is Mach number and c is sound speed, are easily observed. We describe the accidental discovery of this phenomenon in a helium-xenon mixture, subsequent experiments with a helium-argon mixture, and theoretical developments. The phenomenon occurs because a thin layer of the gas adjacent to the wall is immobilized by viscosity while the rest of the gas moves back and forth with the wave, and the heat capacity of the wall holds this thin layer of the gas at constant temperature while the rest of the gas experiences temperature oscillations due to the wave's oscillating pressure. The oscillating temperature gradient causes the light and heavy atoms in the gas to take turns diffusing into and out of the immobilized layer, so that the oscillating motion of the wave outside the immobilized layer tends to carry light-enriched gas in one direction and heavy-enriched gas in the opposite direction. Experiment and theory are in very good agreement for the initial separation fluxes and the saturation mole-fraction differences.

  20. SEPARATION OF GAS MIXTURES BY THERMOACOUSTIC WAVES

    SciTech Connect

    G.W. SWIFT; D.A. GELLER; P.S. SPOOR

    2001-06-01

    Imposing sound on a binary gas mixture in a duct separates the two gases along the acoustic-propagation axis. Mole-fraction differences as large as 10% and separation fluxes as high as 0.001 M-squared c, where M is Mach number and c is sound speed, are easily observed. We describe the accidental discovery of this phenomenon in a helium-xenon mixture, subsequent experiments with a helium-argon mixture, and theoretical developments. The phenomenon occurs because a thin layer of the gas adjacent to the wall is immobilized by viscosity while the rest of the gas moves back and forth with the wave, and the heat capacity of the wall holds this thin layer of the gas at constant temperature while the rest of the gas experiences temperature oscillations due to the wave's oscillating pressure. The oscillating temperature gradient causes the light and heavy atoms in the gas to take turns diffusing into and out of the immobilized layer, so that the oscillating motion of the wave outside the immobilized layer tends to carry light-enriched gas in one direction and heavy-enriched gas in the opposite direction. Experiment and theory are in very good agreement for the initial separation fluxes and the saturation mole-fraction differences.