Science.gov

Sample records for air-gas mixture khitinsoderzhashchie

  1. Small-scale AFBC hot air gas turbine power cycle

    SciTech Connect

    Ashworth, R.A.; Keener, H.M.; Hall, A.W.

    1995-12-31

    The Energy and Environmental Research Corporation (EER), the Ohio Agricultural Research and Development Center (OARDC), the Will-Burt Company (W-B) and the US Department of Energy (DOE) have successfully developed and completed pilot plant tests on a small scale atmospheric fluidized bed combustion (AFBC) system. This system can be used to generate electricity, and/or hot water, steam. Following successful pilot plant operation, commercial demonstration will take place at Cedar Lane Farms (CLF), near Wooster, Ohio. The system demonstration will be completed by the end of 1995. The project is being funded through a cooperative effort between the DOE, EER, W-B, OARDC, CLF and the Ohio Coal Development Office (OCDO). The small scale AFBC, has no internal heat transfer surfaces in the fluid bed proper. Combining the combustor with a hot air gas turbine (HAGT) for electrical power generation, can give a relatively high overall system thermal efficiency. Using a novel method of recovering waste heat from the gas turbine, a gross heat rate of 13,500 Btu/kWhr ({approximately}25% efficiency) can be achieved for a small 1.5 MW{sub e} plant. A low technology industrial recuperation type gas turbine is used that operates with an inlet blade temperature of 1,450 F and a compression ratio of 3.9:1. The AFBC-HAGT technology can be used to generate power for remote rural communities to replace diesel generators, or can be used for small industrial co-generation applications.

  2. Coaxial twin-fluid atomization with pattern air gas streams

    NASA Astrophysics Data System (ADS)

    Hei Ng, Chin; Aliseda, Alberto

    2010-11-01

    Coaxial twin-fluid atomization has numerous industrial applications, most notably fuel injection and spray coating. In the coating process of pharmaceutical tablets, the coaxial atomizing air stream is accompanied by two diametrically opposed side jets that impinge on the liquid/gas coaxial jets at an angle to produce an elliptical shape of the spray's cross section. Our study focuses on the influence of these side jets on the break up process and on the droplet velocity and diameter distribution along the cross section. The ultimate goal is to predict the size distribution and volume flux per unit area in the spray. With this predictive model, an optimal atomizing air/pattern air ratio can be found to achieve the desired coating result. This model is also crucial in scaling up the laboratory setup to production level. We have performed experiments with different atomized liquids, such as water and glycerine-water mixtures, that allow us to establish the effect of liquid viscosity, through the Ohnesorge number, in the spray characteristics. The gas Reynolds number of our experiments ranges from 9000 to 18000 and the Weber number ranges from 400 to 1600. We will present the effect of pattern air in terms of the resulting droplets size, droplet number density and velocity at various distances downstream of the nozzle where the effect of pattern air is significant.

  3. Small-scale AFBC-hot air gas turbine power cycle

    SciTech Connect

    Ashworth, R.C.; Keener, H.M.; Hall, A.W.

    1995-02-01

    The Energy and Environmental Research Corporation (EER), the Ohio Agricultural Research and Development Center (OARDC), the Will-Burt Company (W-B) and the U.S. Department of Energy (DOE) have successfully developed and completed pilot plant tests on a small scale atmospheric fluidized bed combustion (AFBC) system. This system can be used to generate electricity, and/or hot water, steam. Following successful pilot plant operation, commercial demonstration will take place at Cedar Lane Farms (CLF), near Wooster, Ohio. The system demonstration will be completed by the end of 1995. The project is being funded through a cooperative effort between the DOE, EER, W-B, OARDC, CLF and the Ohio Coal Development Office (OCDO). The small scale AFBC, has no internal heat transfer surfaces in the fluid bed proper. Combining the combustor with a hot air gas turbine (HAGT) for electrical power generation, can give a relatively high overall system thermal efficiency. Using a novel method of recovering waste heat from the gas turbine, a gross heat rate of 13,500 Btu/kWhr ({approximately}25% efficiency) can be achieved for a small 1.5 MW, plant. A low technology industrial recuperation type gas turbine is used that operates with an inlet blade temperature of 1450{degrees}F and a compression ratio of 3.9:1. The AFBC-HAGT technology can be used to generate power for remote rural communities to replace diesel generators, or can be used for small industrial co-generation applications.

  4. An atmospheric air gas-liquid diffuse discharge excited by bipolar nanosecond pulse in quartz container used for water sterilization

    NASA Astrophysics Data System (ADS)

    Wang, Sen; Yang, De-Zheng; Wang, Wen-Chun; Zhang, Shuai; Liu, Zhi-Jie; Tang, Kai; Song, Ying

    2013-12-01

    In this Letter, we report that the air gas-liquid diffuse discharge plasma excited by bipolar nanosecond pulse in quartz container with different bottom structures at atmospheric pressure. Optical diagnostic measurements show that bountiful chemically and biologically active species, which are beneficial for effective sterilization in some areas, are produced. Such diffuse plasmas are then used to treat drinking water containing the common microorganisms (Candida albicans and Escherichia coli). It is found that these plasmas can sterilize the microorganisms efficiently.

  5. Combustion characteristics of pulverized coal and air/gas premixed flame in a double swirl combustor

    SciTech Connect

    Kamal, M.M.

    2009-07-01

    An experimental work was performed to investigate the co-firing of pulverized coal and premixed gas/air streams in a double swirl combustor. The results showed that the NOx emissions are affected by the relative rates of thermal NOx formation and destruction via the pyrolysis of the fuel-N species in high temperature fuel-rich zones. Various burner designs were tested in order to vary the temperature history and the residence time across both coal and gas flames inside the furnace. It was found that by injecting the coal with a gas/air mixture as a combined central jet surrounded by a swirled air stream, a double flame envelope develops with high temperature fuel-rich conditions in between the two reaction zones such that the pyrolysis reactions to N{sub 2} are accelerated. A further reduction in the minimum NOx emissions, as well as in the minimum CO concentrations, was reported for the case where the coal particles are fed with the gas/air mixture in the region between the two swirled air streams. On the other hand, allocating the gas/air mixture around the swirled air-coal combustion zone provides an earlier contact with air and retards the NOx reduction mechanism in such a way that the elevated temperatures around the coal particles allow higher overall NOx emissions. The downstream impingement of opposing air jets was found more efficient than the impinging of particle non-laden premixed flames for effective NOx reduction. In both cases, there is an upstream flow from the stagnation region to the coal primary combustion region, but with the case of air impingement, the hot fuel-rich zone develops earlier. The optimum configuration was found by impinging all jets of air and coal-gas/air mixtures that pronounced minimum NOx and CO concentrations of 310 and 480ppm, respectively.

  6. Experimental investigation of deflagration to detonation transition in hydrocarbon-air gaseous mixtures

    SciTech Connect

    Smirnov, N.N.; Tyurnikov, M.V.

    1995-03-01

    The paper presents the results of investigation of deflagration to detonation transition in gas mixtures with exothermic chemical reaction using the experimental method of nonintrusive diagnostics of the process. Schlieren photochronography in the optical sections in different places of the tube is performed using the laser as a source of light. Experimental results of visualization of the transition process in hydrocarbon-air gas mixtures show several different flow patterns: (1) The detonation wave originates in the flame zone. (2) The detonation wave originates between the flame zone and primary shock wave. (3) The secondary combustion zone originates between primary shock and the flame and causes the detonation. (4) Spontaneous flame occurs that leads to the combustion to detonation transition. The influence of the flame zone on the originating strong detonation wave is noticed.

  7. 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).

  8. SEPARATION OF FLUID MIXTURES

    DOEpatents

    Lipscomb, R.; Craig, A.; Labrow, S.; Dunn, J.F.

    1958-10-28

    An apparatus is presented for separating gaseous mixtures by selectively freezing a constituent of the mixture and subsequently separating the frozen gas. The gas mixture is passed through a cylinder fltted with a cooling jacket, causing one gas to freeze on the walls of the cylinder. A set of scraper blades are provided in the interior of the cyllnder, and as the blades oscillate, the frozen gas is scraped to the bottom of the cylinder. Means are provided for the frozen material to pass into a heating chamber where it is vaporized and the product gas collected.

  9. Kinematic separation of mixtures

    SciTech Connect

    Goldshtik, M.; Husain, H.S.; Hussain, F. )

    1992-06-15

    A phenomenon of spontaneous separation of components in an initially uniform fluid mixture is found experimentally. A qualitative explanation of the effect is proposed in terms of nonparallel streamlines in the medium.

  10. Condensate Mixtures and Tunneling

    SciTech Connect

    Timmermans, E.

    1998-09-14

    The experimental study of condensate mixtures is a particularly exciting application of the recently developed atomic-trap Bose-Einstein condensate (BEC) technology: such multiple condensates represent the first laboratory systems of distinguishable boson superfluid mixtures. In addition, as the authors point out in this paper, the possibility of inter-condensate tunneling greatly enhances the richness of the condensate mixture physics. Not only does tunneling give rise to the oscillating particle currents between condensates of different chemical potentials, such as those studied extensively in the condensed matter Josephson junction experiments, it also affects the near-equilibrium dynamics and stability of the condensate mixtures. In particular, the stabilizing influence of tunneling with respect to spatial separation (phase separation) could be of considerable practical importance to the atomic trap systems. Furthermore, the creation of mixtures of atomic and molecular condensates could introduce a novel type of tunneling process, involving the conversion of a pair of atomic condensate bosons into a single molecular condensate boson. The static description of condensate mixtures with such type of pair tunneling suggests the possibility of observing dilute condensates with the liquid-like property of a self-determined density.

  11. Experimental study of wood downdraft gasification for an improved producer gas quality through an innovative two-stage air and premixed air/gas supply approach.

    PubMed

    Jaojaruek, Kitipong; Jarungthammachote, Sompop; Gratuito, Maria Kathrina B; Wongsuwan, Hataitep; Homhual, Suwan

    2011-04-01

    This study conducted experiments on three different downdraft gasification approaches: single stage, conventional two-stage, and an innovative two-stage air and premixed air/gas supply approach. The innovative two-stage approach has two nozzle locations, one for air supply at combustion zone and the other located at the pyrolysis zone for supplying the premixed gas (air and producer gas). The producer gas is partially bypassed to mix with air and supplied to burn at the pyrolysis zone. The result shows that producer gas quality generated by the innovative two-stage approach improved as compared to conventional two-stage. The higher heating value (HHV) increased from 5.4 to 6.5 MJ/Nm(3). Tar content in producer gas reduced to less than 45 mg/Nm(3). With this approach, gas can be fed directly to an internal combustion engine. Furthermore, the gasification thermal efficiency also improved by approximately 14%. The approach gave double benefits on gas qualities and energy savings. PMID:21292477

  12. 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...

  13. Combustion of Gaseous Mixtures

    NASA Technical Reports Server (NTRS)

    Duchene, R

    1932-01-01

    This report not only presents matters of practical importance in the classification of engine fuels, for which other means have proved inadequate, but also makes a few suggestions. It confirms the results of Withrow and Boyd which localize the explosive wave in the last portions of the mixture burned. This being the case, it may be assumed that the greater the normal combustion, the less the energy developed in the explosive form. In order to combat the detonation, it is therefore necessary to try to render the normal combustion swift and complete, as produced in carbureted mixtures containing benzene (benzol), in which the flame propagation, beginning at the spark, yields a progressive and pronounced darkening on the photographic film.

  14. 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.

  15. Evaluating Whole Chemical Mixtures and Sufficient Similarity

    EPA Science Inventory

    This powerpoint presentation supports apresentation describing dose-response assessment for complex chemical mixtures including deriving reference doses for mixtures evaluating sufficient similarity among chemical mixtures.

  16. Toxicological evaluation of chemical mixtures.

    PubMed

    Feron, V J; Groten, J P

    2002-06-01

    This paper addresses major developments in the safety evaluation of chemical mixtures during the past 15 years, reviews today's state of the art of mixture toxicology, and discusses challenges ahead. Well-thought-out tailor-made mechanistic and empirical designs for studying the toxicity of mixtures have gradually substituted trial-and-error approaches, improving the insight into the testability of joint action and interaction of constituents of mixtures. The acquired knowledge has successfully been used to evaluate the safety of combined exposures and complex mixtures such as, for example, the atmosphere at hazardous waste sites, drinking water disinfection by-products, natural flavouring complexes, and the combined intake of food additives. To consolidate the scientific foundation of mixture toxicology, studies are in progress to revisit the biological concepts and mathematics underlying formulas for low-dose extrapolation and risk assessment of chemical mixtures. Conspicuous developments include the production of new computer programs applicable to mixture research (CombiTool, BioMol, Reaction Network Modelling), the application of functional genomics and proteomics to mixture studies, the use of nano-optochemical sensors for in vivo imaging of physiological processes in cells, and the application of optical sensor micro- and nano-arrays for complex sample analysis. Clearly, the input of theoretical biologists, biomathematicians and bioengineers in mixture toxicology is essential for the development of this challenging branch of toxicology into a scientific subdiscipline of full value. PMID:11983277

  17. 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

  18. Stabilizer for fuel mixtures

    SciTech Connect

    Abe, M.; Moriyama, N.; Yamamura, M.

    1981-02-24

    A stabilizer for fuel mixtures of finely divided coal and fuel oil is composed of an active ingredient, a non-ionic surface active agent consisting of a block copolymer represented by the following general formula (I): R/sub 1/O-(C/sub 2/H/sup 4/O)l-(C/sub 3/H/sup 6/O)m-(C/sub 2/H/sup 4/O)n-R/sub 2/ (I) wherein r/sub 1/ and r/sub 2/ stand for a hydrogen atom or an alklyl group having 1 to 6 carbon atoms, the mole number (L+n) of added ethylene oxide is in the range of from 30 to 300, the mole number (M) of added propylene oxide is in the range of from 15 to 80, and the content of ethylene oxide in the whole molecule is 40 to 85% by weight.

  19. 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

  20. 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

  1. Thermophysical Properties of Hydrocarbon Mixtures

    National Institute of Standards and Technology Data Gateway

    SRD 4 NIST Thermophysical Properties of Hydrocarbon Mixtures (PC database for purchase)   Interactive computer program for predicting thermodynamic and transport properties of pure fluids and fluid mixtures containing up to 20 components. The components are selected from a database of 196 components, mostly hydrocarbons.

  2. Thermobaric investigation of coal mixtures

    SciTech Connect

    Kosinskii, V.A.

    1983-01-01

    An examination of the dynamics of gas emission during the heating in vacuo of different grades of Donbass coal included a study of binary and ternary mixtures of these coals. Discrete gas emission was established at temperatures depending principally on the ratio of coals within the mixtures. The data obtained could be used as a basis for commercial processes.

  3. Latent classiness and other mixtures.

    PubMed

    Neale, Michael C

    2014-05-01

    The aim of this article is to laud Lindon Eaves' role in the development of mixture modeling in genetic studies. The specification of models for mixture distributions was very much in its infancy when Professor Eaves implemented it in his own FORTRAN programs, and extended it to data collected from relatives such as twins. It was his collaboration with the author of this article which led to the first implementation of mixture distribution modeling in a general-purpose structural equation modeling program, Mx, resulting in a 1996 article on linkage analysis in Behavior Genetics. Today, the popularity of these methods continues to grow, encompassing methods for genetic association, latent class analysis, growth curve mixture modeling, factor mixture modeling, regime switching, marginal maximum likelihood, genotype by environment interaction, variance component twin modeling in the absence of zygosity information, and many others. This primarily historical article concludes with some consideration of some possible future developments. PMID:24477932

  4. Latent Classiness and Other Mixtures

    PubMed Central

    Neale, Michael C.

    2014-01-01

    The aim of this article is to laud Lindon Eaves’ role in the development of mixture modeling in genetic studies. The specification of models for mixture distributions was very much in its infancy when Professor Eaves implemented it in his own FORTRAN programs, and extended it to data collected from relatives such as twins. It was his collaboration with the author of this article which led to the first implementation of mixture distribution modeling in a general-purpose structural equation modeling program, Mx, resulting in a 1996 article on linkage analysis in Behavior Genetics. Today, the popularity of these methods continues to grow, encompassing methods for genetic association, latent class analysis, growth curve mixture modeling, factor mixture modeling, regime switching, marginal maximum likelihood, genotype by environment interaction, variance component twin modeling in the absence of zygosity information, and many others. This primarily historical article concludes with some consideration of some possible future developments. PMID:24477932

  5. Thermobaric investigations of coal mixtures

    SciTech Connect

    Kosinskii, V.A.

    1983-01-01

    The dynamics of the evolution of gas when coals of various types from the Donbass and binary and ternary mixtures of them are heated have been studied. The discrete nature of the evolution of gas has been established, the temperature intervals of which depend primarily on the ratio of the coals in the mixtures. The possibility of using the results obtained in determining rational schemes for the industrial processing of coals is suggested.

  6. Ionization coefficients in gas mixtures

    NASA Astrophysics Data System (ADS)

    Marić, D.; Šašić, O.; Jovanović, J.; Radmilović-Rađenović, M.; Petrović, Z. Lj.

    2007-03-01

    We have tested the application of the common E/N ( E—electric field, N—gas number density) or Wieland approximation [Van Brunt, R.J., 1987. Common parametrizations of electron transport, collision cross section, and dielectric strength data for binary gas mixtures. J. Appl. Phys. 61 (5), 1773-1787.] and the common mean energy (CME) combination of the data for pure gases to obtain ionization coefficients for mixtures. Test calculations were made for Ar-CH4, Ar-N2, He-Xe and CH4-N2 mixtures. Standard combination procedure gives poor results in general, due to the fact that the electron energy distribution is considerably different in mixtures and in individual gases at the same values of E/N. The CME method may be used for mixtures of gases with ionization coefficients that do not differ by more than two orders of magnitude which is better than any other technique that was proposed [Marić, D., Radmilović-Rađenović, M., Petrović, Z.Lj., 2005. On parametrization and mixture laws for electron ionization coefficients. Eur. Phys. J. D 35, 313-321.].

  7. Calculation of gas temperature at the outlet of the combustion chamber and in the air-gas channel of a gas-turbine unit by data of acceptance tests in accordance with ISO

    NASA Astrophysics Data System (ADS)

    Kostyuk, A. G.; Karpunin, A. P.

    2016-01-01

    This article describes a high accuracy method enabling performance of the calculation of real values of the initial temperature of a gas turbine unit (GTU), i.e., the gas temperature at the outlet of the combustion chamber, in a situation where manufacturers do not disclose this information. The features of the definition of the initial temperature of the GTU according to ISO standards were analyzed. It is noted that the true temperatures for high-temperature GTUs is significantly higher than values determined according to ISO standards. A computational procedure for the determination of gas temperatures in the air-gas channel of the gas turbine and cooling air consumptions over blade rims is proposed. As starting equations, the heat balance equation and the flow mixing equation for the combustion chamber are assumed. Results of acceptance GTU tests according to ISO standards and statistical dependencies of required cooling air consumptions on the gas temperature and the blade metal are also used for calculations. An example of the calculation is given for one of the units. Using a developed computer program, the temperatures in the air-gas channel of certain GTUs are calculated, taking into account their design features. These calculations are performed on the previously published procedure for the detailed calculation of the cooled gas turbine subject to additional losses arising because of the presence of the cooling system. The accuracy of calculations by the computer program is confirmed by conducting verification calculations for the GTU of the Mitsubishi Comp. and comparing results with published data of the company. Calculation data for temperatures were compared with the experimental data and the characteristics of the GTU, and the error of the proposed method is estimated.

  8. 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

  9. Bayesian Kernel Mixtures for Counts.

    PubMed

    Canale, Antonio; Dunson, David B

    2011-12-01

    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

  10. 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…

  11. Landfilling ash/sludge mixtures

    SciTech Connect

    Benoit, J.; Eighmy, T.T.; Crannell, B.S.

    1999-10-01

    The geotechnical properties of a mixture of municipal solid waste incinerator bottom ash and municipal wastewater treatment plant sludge was investigated for a proposed ash/sludge secure landfill. The components as well as mixtures ranging from 10:1 to 5:1 (ash:sludge, by volume) were evaluated, where appropriate, for a number of geotechnical index and mechanical properties including particle size, water content, specific gravity, density-moisture relationships, shear strength, and compressibility. The results from a compactibility study and stability analysis of the proposed landfill were used to help approve a landfill codisposal concept; a full-scale facility was constructed and is currently operating successfully.

  12. Estimating proportions of materials using mixture models

    NASA Technical Reports Server (NTRS)

    Heydorn, R. P.; Basu, R.

    1983-01-01

    An approach to proportion estimation based on the notion of a mixture model, appropriate parametric forms for a mixture model that appears to fit observed remotely sensed data, methods for estimating the parameters in these models, methods for labelling proportion determination from the mixture model, and methods which use the mixture model estimates as auxiliary variable values in some proportion estimation schemes are addressed.

  13. Uphill diffusion in multicomponent mixtures.

    PubMed

    Krishna, Rajamani

    2015-05-21

    Molecular diffusion is an omnipresent phenomena that is important in a wide variety of contexts in chemical, physical, and biological processes. In the majority of cases, the diffusion process can be adequately described by Fick's law that postulates a linear relationship between the flux of any species and its own concentration gradient. Most commonly, a component diffuses down the concentration gradient. The major objective of this review is to highlight a very wide variety of situations that cause the uphill transport of one constituent in the mixture. Uphill diffusion may occur in multicomponent mixtures in which the diffusion flux of any species is strongly coupled to that of its partner species. Such coupling effects often arise from strong thermodynamic non-idealities. For a quantitative description we need to use chemical potential gradients as driving forces. The transport of ionic species in aqueous solutions is coupled with its partner ions because of the electro-neutrality constraints; such constraints may accelerate or decelerate a specific ion. When uphill diffusion occurs, we observe transient overshoots during equilibration; the equilibration process follows serpentine trajectories in composition space. For mixtures of liquids, alloys, ceramics and glasses the serpentine trajectories could cause entry into meta-stable composition zones; such entry could result in phenomena such as spinodal decomposition, spontaneous emulsification, and the Ouzo effect. For distillation of multicomponent mixtures that form azeotropes, uphill diffusion may allow crossing of distillation boundaries that are normally forbidden. For mixture separations with microporous adsorbents, uphill diffusion can cause supra-equilibrium loadings to be achieved during transient uptake within crystals; this allows the possibility of over-riding adsorption equilibrium for achieving difficult separations. PMID:25761383

  14. Spinodal decomposition in binary mixtures

    NASA Astrophysics Data System (ADS)

    Mauri, Roberto; Shinnar, Reuel; Triantafyllou, George

    1996-03-01

    We study the early stage of the phase separation of a binary mixture far from its critical point of demixing. Whenever the mixture of two mutually repulsive species is quenched to a temperature below its critical point of miscibility, the effect of the enthalpic repulsive force prevails upon the entropic tendency to mix, so that the system eventually separates itno two coexisting phases. We have developed a highly nonlinear model, in close analogy with the linear theory of Cahn and Hilliard, where a generalized free energy is defined in terms of two parameters ψ and a, the first describing the equilibrium composition of the two phases, ad the second denoting a characteristic length scale that is inversely proportional to the equilibrium surface tension. The linear stability analysis predicts that any perturbation of the initial mixture composition with wave number k smaller than √2ψ /a will grow exponentially in time, with a maximum growth corresponding to kmax= √ψ /a. A numerical solution of the equation shows that nonlinear effects saturate the exponential growth, and that the concentraiton distribution tends to a steady state, peroidic profile with wavelength λ=2πa/ √ψ corresponding to the fastest growing mode of the linear regime. The main result of our theoretical model is that this steady state does not depend on the form of the initial perturbation to the homogeneous composition profile.

  15. 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.

  16. 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...

  17. Uncertainty in Mixtures and Cumulative Risk Assessment

    EPA Science Inventory

    Humans and environmental species are rarely exposed to single chemicals. These chemicals typically affect multiple tissues through multiple modes of action, which may depend on the dose. Mixtures risk assessment may employ dose response information from the mixture of interest,...

  18. 14 CFR 27.1147 - Mixture controls.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Mixture controls. 27.1147 Section 27.1147... STANDARDS: NORMAL CATEGORY ROTORCRAFT Powerplant Powerplant Controls and Accessories § 27.1147 Mixture controls. If there are mixture controls, each engine must have a separate control and the controls must...

  19. 14 CFR 23.1147 - Mixture controls.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Mixture controls. 23.1147 Section 23.1147... STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Powerplant Powerplant Controls and Accessories § 23.1147 Mixture controls. (a) If there are mixture controls, each engine must have a...

  20. 14 CFR 29.1147 - Mixture controls.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Mixture controls. 29.1147 Section 29.1147... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Powerplant Controls and Accessories § 29.1147 Mixture controls. (a) If there are mixture controls, each engine must have a separate control, and the...

  1. 14 CFR 25.1147 - Mixture controls.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Mixture controls. 25.1147 Section 25.1147... STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Powerplant Controls and Accessories § 25.1147 Mixture controls. (a) If there are mixture controls, each engine must have a separate control. The controls must...

  2. 14 CFR 23.1147 - Mixture controls.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Mixture controls. 23.1147 Section 23.1147... STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Powerplant Powerplant Controls and Accessories § 23.1147 Mixture controls. (a) If there are mixture controls, each engine must have a...

  3. Investigations of reversible thermochromic mixtures

    NASA Astrophysics Data System (ADS)

    MacLaren, Douglas C.

    Three-component organic thermochromic systems have potential applications in reversible, rewritable thermal printing. In principle, such mixtures could maintain a coloured or non-coloured state at ambient temperature depending on their thermal treatment. These systems generally consist of a functional dye (1--3 mol%), a weakly acidic colour developer (5--25 mol%), and a high-melting organic solvent (75--90 mol%). Colour development occurs at the fusion temperature of the mixture, which triggers the interaction of the dye and developer. Slow cooling of the melt results in an equilibrium state with low colour density, whereas rapid cooling of the melt results in a metastable state with high colour density. The metastable state can be decoloured by heating to an intermediate decolourisation temperature at which the coloured state becomes unstable. Barriers to the widespread use of reversible, rewritable thermochromic materials include problems with colour contrast, colour stability, and decolourisation rates. Development is hindered by a lack of detailed knowledge of the interactions between components in these systems. In this study the developer-dye and developer-solvent interactions were examined for an archetypal dye/developer/solvent thermochromic system. Vibrational spectroscopy, NMR, and thermal analysis were used to examine compounds formed in developer/dye and developer/solvent binary mixtures. Rewritable thermochromic properties such as metastable colour density, equilibrium colour density, and decolourisation rates were examined and discussed in terms of the thermodynamics of the developer/dye and developer/solvent interactions. Observed thermochromic properties are shown to be strongly correlated to a competition between the dye and the solvent for interaction with the developer. Increasing the attractive interaction between the solvent and developer results in enhanced rewritable thermochromic properties.

  4. Mixture Models for Dependent Observations

    NASA Technical Reports Server (NTRS)

    Peters, C.

    1983-01-01

    Parametric mixture models appropriate for data presented in homogeneous blocks of varying sizes from several unidentified source populations are considered. For most applications, the data elements within each block are dependent. Models are proposed for multivariate normal data incorporating two types of dependence, exchangeability of elements within blocks, and a Markov structure for blocks. The consequences of assuming exchangeability, when in fact the Markov structure holds, are explored. Computational problems for each model are considered, and results of a simple test of the exchangeability hypothesis for LANDSAT data are presented.

  5. Effect of Cement on Emulsified Asphalt Mixtures

    NASA Astrophysics Data System (ADS)

    Oruc, Seref; Celik, Fazil; Akpinar, M. Vefa

    2007-10-01

    Emulsified asphalt mixtures have environmental, economical, and logistical advantages over hot mixtures. However, they have attracted little attention as structural layers due to their inadequate performance and susceptibility to early life damage by rainfall. The objective of this article is to provide an improved insight into how the mechanical properties of emulsion mixtures may be improved and to determine the influence of cement on emulsified asphalt mixtures. Laboratory tests on strength, temperature susceptibility, water damage, creep and permanent deformation were implemented to evaluate the mechanical properties of emulsified asphalt mixtures. The test results showed that mechanical properties of emulsified asphalt mixtures have significantly improved with Portland cement addition. This experimental study suggested that cement modified asphalt emulsion mixtures might be an alternate way of a structural layer material in pavement.

  6. 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.

  7. Mixture distributions in human genetics research.

    PubMed

    Schork, N J; Allison, D B; Thiel, B

    1996-06-01

    The use of mixture distributions in genetics research dates back to at least the late 1800s when Karl Pearson applied them in an analysis of crab morphometry. Pearson's use of normal mixture distributions to model the mixing of different species of crab (or 'families' of crab as he referred to them) within a defined geographic area motivated further use of mixture distributions in genetics research settings, and ultimately led to their development and recognition as intuitive modelling devices for the effects of underlying genes on quantitative phenotypic (i.e. trait) expression. In addition, mixture distributions are now used routinely to model or accommodate the genetic heterogeneity thought to underlie many human diseases. Specific applications of mixture distribution models in contemporary human genetics research are, in fact, too numerous to count. Despite this long, consistent and arguably illustrious history of use, little mention of mixture distributions in genetics research is made in many recent reviews on mixture models. This review attempts to rectify this by providing insight into the role that mixture distributions play in contemporary human genetics research. Tables providing examples from the literature that describe applications of mixture models in human genetics research are offered as a way of acquainting the interested reader with relevant studies. In addition, some of the more problematic aspects of the use of mixture models in genetics research are outlined and addressed. PMID:8817796

  8. 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

  9. Performance-based asphalt mixture design methodology

    NASA Astrophysics Data System (ADS)

    Ali, Al-Hosain Mansour

    Today, several State D.O.T.s are being investigating the use of tire rubber with local conventional materials. Several of the ongoing investigations identified potential benefits from the use of these materials, including improvements in material properties and performance. One of the major problems is being associated with the transferability of asphalt rubber technology without appropriately considering the effects of the variety of conventional materials on mixture behavior and performance. Typically, the design of these mixtures is being adapted to the physical properties of the conventional materials by using the empirical Marshall mixture design and without considering fundamental mixture behavior and performance. Use of design criteria related to the most common modes of failure for asphalt mixtures, such as rutting, fatigue cracking, and low temperature thermal cracking have to be developed and used for identifying the "best mixture," in term of performance, for the specific local materials and loading conditions. The main objective of this study was the development of a mixture design methodology that considers mixture behavior and performance. In order to achieve this objective a laboratory investigation able to evaluate mixture properties that can be related to mixture performance, (in terms of rutting, low temperature cracking, moisture damage and fatigue), and simulating the actual field loading conditions that the material is being exposed to, was conducted. The results proved that the inclusion of rubber into asphalt mixtures improved physical characteristics such as elasticity, flexibility, rebound, aging properties, increased fatigue resistance, and reduced rutting potential. The possibility of coupling the traditional Marshall mix design method with parameters related to mixture behavior and performance was investigated. Also, the SHRP SUPERPAVE mix design methodology was reviewed and considered in this study for the development of an integrated

  10. Thermodynamic Calculations for Complex Chemical Mixtures

    NASA Technical Reports Server (NTRS)

    Mcbride, B. J.

    1986-01-01

    General computer program, CECTRP, developed for calculation of thermodynamic properties of complex mixtures with option to calculate transport properties of these mixtures. Free-energy minimization technique used in equilibrium calculation. Rigorous equations used in transport calculations. Program calculates equilibrium compositions and corresponding thermodynamic and transport properties of mixtures. CECTRP accommodates up to 24 reactants, 20 elements, and 600 products, 400 of which are condensed. Written in FORTRAN IV for any large computer system.

  11. Toxicology of chemical mixtures: international perspective.

    PubMed Central

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

    1998-01-01

    This paper reviews major activities outside the United States on human health issues related to chemical mixtures. In Europe an international study group on combination effects has been formed and has started by defining synergism and antagonism. Successful research programs in Europe include the development and application of statistically designed experiments combined with multivariate data analysis and modeling in vitro and in vivo studies on a wide variety of chemicals such as petroleum hydrocarbons, aldehydes, food contaminants, industrial solvents, and mycotoxins. Other major activities focus on the development of safety evaluation strategies for mixtures such as the use of toxic equivalence factors or alternatives such as the question-and-answer approach, fractionation followed by recombination of the mixture in combination with a mixture design, and quantitative structure-activity relationship analysis combined with lumping analysis and physiologically based pharmacokinetic/pharmacodynamic modeling for studying complex mixtures. A scheme for hazard identification and risk assessment of complex mixtures and a consistent way to generate total volatile organic compound values for indoor air have also been developed. Examples of other activities are carcinogenicity studies on complex mixtures (petroleum middle distillates, foundry fumes, pesticides, heterocyclic amines, diesel exhaust, solid particles), neurotoxicity studies of mixtures of solvents alone or in combination with exposure to physical factors, and toxicity studies of outdoor air pollutants, focusing on particulates. Outside the United States, toxicologists and regulators clearly have a growing interest in the toxicology and risk assessment of chemical mixtures. PMID:9860882

  12. Cluster kinetics model for mixtures of glassformers.

    PubMed

    Brenskelle, Lisa A; McCoy, Benjamin J

    2007-10-14

    For glassformers we propose a binary mixture relation for parameters in a cluster kinetics model previously shown to represent pure compound data for viscosity and dielectric relaxation as functions of either temperature or pressure. The model parameters are based on activation energies and activation volumes for cluster association-dissociation processes. With the mixture parameters, we calculated dielectric relaxation times and compared the results to experimental values for binary mixtures. Mixtures of sorbitol and glycerol (seven compositions), sorbitol and xylitol (three compositions), and polychloroepihydrin and polyvinylmethylether (three compositions) were studied. PMID:17935407

  13. 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.

  14. Cluster kinetics model for mixtures of glassformers

    NASA Astrophysics Data System (ADS)

    Brenskelle, Lisa A.; McCoy, Benjamin J.

    2007-10-01

    For glassformers we propose a binary mixture relation for parameters in a cluster kinetics model previously shown to represent pure compound data for viscosity and dielectric relaxation as functions of either temperature or pressure. The model parameters are based on activation energies and activation volumes for cluster association-dissociation processes. With the mixture parameters, we calculated dielectric relaxation times and compared the results to experimental values for binary mixtures. Mixtures of sorbitol and glycerol (seven compositions), sorbitol and xylitol (three compositions), and polychloroepihydrin and polyvinylmethylether (three compositions) were studied.

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

    SciTech Connect

    Teuschler, Linda K.

    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.

  16. Simulation of mixture microstructures via particle packing models and their direct comparison with real mixtures

    NASA Astrophysics Data System (ADS)

    Gulliver, Eric A.

    The objective of this thesis to identify and develop techniques providing direct comparison between simulated and real packed particle mixture microstructures containing submicron-sized particles. This entailed devising techniques for simulating powder mixtures, producing real mixtures with known powder characteristics, sectioning real mixtures, interrogating mixture cross-sections, evaluating and quantifying the mixture interrogation process and for comparing interrogation results between mixtures. A drop and roll-type particle-packing model was used to generate simulations of random mixtures. The simulated mixtures were then evaluated to establish that they were not segregated and free from gross defects. A powder processing protocol was established to provide real mixtures for direct comparison and for use in evaluating the simulation. The powder processing protocol was designed to minimize differences between measured particle size distributions and the particle size distributions in the mixture. A sectioning technique was developed that was capable of producing distortion free cross-sections of fine scale particulate mixtures. Tessellation analysis was used to interrogate mixture cross sections and statistical quality control charts were used to evaluate different types of tessellation analysis and to establish the importance of differences between simulated and real mixtures. The particle-packing program generated crescent shaped pores below large particles but realistic looking mixture microstructures otherwise. Focused ion beam milling was the only technique capable of sectioning particle compacts in a manner suitable for stereological analysis. Johnson-Mehl and Voronoi tessellation of the same cross-sections produced tessellation tiles with different the-area populations. Control charts analysis showed Johnson-Mehl tessellation measurements are superior to Voronoi tessellation measurements for detecting variations in mixture microstructure, such as altered

  17. Time-dependence in mixture toxicity prediction

    PubMed Central

    Dawson, Douglas A.; Allen, Erin M.G.; Allen, Joshua L.; Baumann, Hannah J.; Bensinger, Heather M.; Genco, Nicole; Guinn, Daphne; Hull, Michael W.; Il'Giovine, Zachary J.; Kaminski, Chelsea M.; Peyton, Jennifer R.; Schultz, T. Wayne; Pöch, Gerald

    2014-01-01

    The value of time-dependent toxicity (TDT) data in predicting mixture toxicity was examined. Single chemical (A and B) and mixture (A + B) toxicity tests using Microtox® were conducted with inhibition of bioluminescence (Vibrio fischeri) being quantified after 15, 30 and 45-min of exposure. Single chemical and mixture tests for 25 sham (A1:A2) and 125 true (A:B) combinations had a minimum of seven duplicated concentrations with a duplicated control treatment for each test. Concentration/response (x/y) data were fitted to sigmoid curves using the five-parameter logistic minus one parameter (5PL-1P) function, from which slope, EC25, EC50, EC75, asymmetry, maximum effect, and r2 values were obtained for each chemical and mixture at each exposure duration. Toxicity data were used to calculate percentage-based TDT values for each individual chemical and mixture of each combination. Predicted TDT values for each mixture were calculated by averaging the TDT values of the individual components and regressed against the observed TDT values obtained in testing, resulting in strong correlations for both sham (r2 = 0.989, n = 25) and true mixtures (r2 = 0.944, n = 125). Additionally, regression analyses confirmed that observed mixture TDT values calculated for the 50% effect level were somewhat better correlated with predicted mixture TDT values than at the 25 and 75% effect levels. Single chemical and mixture TDT values were classified into five levels in order to discern trends. The results suggested that the ability to predict mixture TDT by averaging the TDT of the single agents was modestly reduced when one agent of the combination had a positive TDT value and the other had a minimal or negative TDT value. PMID:25446331

  18. Ultracentrifuge for separating fluid mixtures

    DOEpatents

    Lowry, Ralph A.

    1976-01-01

    1. A centrifuge for the separation of fluid mixtures having light and heavy fractions comprising a cylindrical rotor, disc type end-plugs closing the ends of the rotor, means for mounting said rotor for rotation about its cylindrical axis, a housing member enclosing the rotor, a vacuum chamber in said housing about the central portion of the rotor, a collection chamber at each end of the housing, the innermost side of which is substantially formed by the outer face of the end-plug, means for preventing flow of the fluid from the collection chambers to said vacuum chamber, at least one of said end-plugs having a plurality of holes therethrough communicating between the collection chamber adjacent thereto and the inside of the rotor to induce countercurrent flow of the fluid in the centrifuge, means for feeding fluid to be processed into the centrifuge, means communicating with the collection chambers to extract the light and heavy separated fractions of the fluid, and means for rotating the rotor.

  19. 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.

  20. 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.

  1. Gas mixtures for spark gap closing switches

    DOEpatents

    Christophorou, Loucas G.; McCorkle, Dennis L.; Hunter, Scott R.

    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.

  2. Strategies for toxicological evaluation of mixtures.

    PubMed

    Eide, I

    1996-01-01

    Different strategies for the toxicological evaluation of mixtures are presented. The purpose is to determine the effects of each component (variable) in the mixture, and possible interactions between variables. The examples presented have 3-5 predictor variables and 1-3 responses, and are based on statistical experimental design, multivariate data analysis and modelling. The following examples are presented: (1) inhalation experiments with synthetic vapour mixtures of hydrocarbons formulated by means of mixture design at different vapour concentrations (the experimental) region covers both partial and complete evaporation of the liquid mixtures); (2) combination of refinery streams for fuel blending by means of mixture design with constraints, followed by engine tests and determination of exhaust particles; (3) fractionation of organic extracts of diesel exhaust particles, and recombination of the extracts by means of mixture design, followed by mutagenicity testing of the recombined extracts in the Ames Salmonella assay; (4) spiking complex mixtures with individual compounds using factorial design, and subsequent mutagenicity testing. The data obtained from these four examples were analysed by means of Projections to Latent Structures (PLS). The effects of each variable and possible interactions, were quantified by means of PLS regression coefficients. Furthermore, the empirical models obtained were evaluated by means of correlation coefficients, cross validation and predictions. PMID:9119328

  3. 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...

  4. The Potential of Growth Mixture Modelling

    ERIC Educational Resources Information Center

    Muthen, Bengt

    2006-01-01

    The authors of the paper on growth mixture modelling (GMM) give a description of GMM and related techniques as applied to antisocial behaviour. They bring up the important issue of choice of model within the general framework of mixture modelling, especially the choice between latent class growth analysis (LCGA) techniques developed by Nagin and…

  5. Laser kinetic processes in dye mixtures

    SciTech Connect

    Lei Jie; Fu Honglang

    1988-11-01

    Radiation from rhodamine 6G+cresyl violet and rhodamine B+cresyl violet dye mixtures in ethyl alcohol pumped by N/sub 2/ laser light were studied. The rate constants of resonant transfer in the mixtures were determined. The radiative transfer processes are discussed.

  6. THE RECOVERY OF URANIUM FROM GAS MIXTURE

    DOEpatents

    Jury, S.H.

    1964-03-17

    A method of separating uranium from a mixture of uranium hexafluoride and other gases is described that comprises bringing the mixture into contact with anhydrous calcium sulfate to preferentially absorb the uranium hexafluoride on the sulfate. The calcium sulfate is then leached with a selective solvent for the adsorbed uranium. (AEC)

  7. Mixture Modeling of Individual Learning Curves

    ERIC Educational Resources Information Center

    Streeter, Matthew

    2015-01-01

    We show that student learning can be accurately modeled using a mixture of learning curves, each of which specifies error probability as a function of time. This approach generalizes Knowledge Tracing [7], which can be viewed as a mixture model in which the learning curves are step functions. We show that this generality yields order-of-magnitude…

  8. 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.

  9. Prediction of viscosity of dense fluid mixtures

    NASA Astrophysics Data System (ADS)

    Royal, Damian D.; Vesovic, Velisa; Trusler, J. P. Martin; Wakeham, William. A.

    The Vesovic-Wakeham (VW) method of predicting the viscosity of dense fluid mixtures has been improved by implementing new mixing rules based on the rigid sphere formalism. The proposed mixing rules are based on both Lebowitz's solution of the Percus-Yevick equation and on the Carnahan-Starling equation. The predictions of the modified VW method have been compared with experimental viscosity data for a number of diverse fluid mixtures: natural gas, hexane + hheptane, hexane + octane, cyclopentane + toluene, and a ternary mixture of hydrofluorocarbons (R32 + R125 + R134a). The results indicate that the proposed improvements make possible the extension of the original VW method to liquid mixtures and to mixtures containing polar species, while retaining its original accuracy.

  10. Supercritical separation process for complex organic mixtures

    DOEpatents

    Chum, Helena L.; Filardo, Giuseppe

    1990-01-01

    A process is disclosed for separating low molecular weight components from complex aqueous organic mixtures. The process includes preparing a separation solution of supercritical carbon dioxide with an effective amount of an entrainer to modify the solvation power of the supercritical carbon dioxide and extract preselected low molecular weight components. The separation solution is maintained at a temperature of at least about 70.degree. C. and a pressure of at least about 1,500 psi. The separation solution is then contacted with the organic mixtures while maintaining the temperature and pressure as above until the mixtures and solution reach equilibrium to extract the preselected low molecular weight components from the organic mixtures. Finally, the entrainer/extracted components portion of the equilibrium mixture is isolated from the separation solution.

  11. 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.

  12. Relativistic mixtures of charged and uncharged particles

    NASA Astrophysics Data System (ADS)

    Kremer, Gilberto M.

    2014-01-01

    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.

  13. Mixture of Skewed α-Stable Distributions

    NASA Astrophysics Data System (ADS)

    Shojaei, S. R. Hosseini; Nassiri, V.; Mohammadian, Gh. R.; Mohammadpour, A.

    2011-03-01

    Expectation maximization (EM) algorithm and the Bayesian techniques are two approaches for statistical inference of mixture models [3, 4]. By noting the advantages of the Bayesian methods, practitioners prefer them. However, implementing Markov chain Monte Carlo algorithms can be very complicated for stable distributions, due to the non-analytic density or distribution function formulas. In this paper, we introduce a new class of mixture of heavy-tailed distributions, called mixture of skewed stable distributions. Skewed stable distributions belongs to the exponential family and they have analytic density representation. It is shown that skewed stable distributions dominate skew stable distribution functions and they can be used to model heavy-tailed data. The class of skewed stable distributions has an analytic representation for its density function and the Bayesian inference can be done similar to the exponential family of distributions. Finally, mixture of skewed stable distributions are compared to the mixture of stable distributions through a simulations study.

  14. Environmental complex mixture toxicity assessment.

    PubMed Central

    Gardner, H S; Brennan, L M; Toussaint, M W; Rosencrance, A B; Boncavage-Hennessey, E M; Wolfe, M J

    1998-01-01

    Trichloroethylene (TCE) was found as a contaminant in the well supplying water to an aquatic testing laboratory. The groundwater was routinely screened by a commercial laboratory for volatile and semivolatile compounds, metals, herbicides, pesticides, and polychlorinated biphenyls using U.S. Environmental Protection Agency methods. Although TCE was the only reportable peak on the gas chromatograph, with average concentrations of 0.200 mg/l, other small peaks were also present, indicating the possibility that the contamination was not limited to TCE alone. A chronic 6-month carcinogenicity assay was conducted on-site in a biomonitoring trailer, using the Japanese medaka fish (Oryzias latipes) in an initiation-promotion protocol, with diethylnitrosamine (DEN) as the initiator and the TCE-contaminated groundwater as a promoter. Study results indicated no evidence of carcinogenic potential of the groundwater without initiation. There was, however, a tumor-promotional effect of the groundwater after DEN initiation. A follow-up laboratory study was conducted using reagent grade TCE added to carbon-filtered groundwater to simulate TCE concentrations comparable to those found in the contaminated groundwater. Study results indicated no promotional effects of TCE. These studies emphasize the necessity for on-site bioassays to assess potential environmental hazards. In this instance, chemical analysis of the groundwater identified TCE as the only reportable contaminant, but other compounds present below reportable limits were noted and may have had a synergistic effect on tumor promotion observed with the groundwater exposure. Laboratory toxicity testing of single compounds can produce toxicity data specific to that compound for that species but cannot take into account the possible toxic effects of mixtures of compounds. Images Figure 2 PMID:9860885

  15. Foaming of mixtures of pure hydrocarbons

    NASA Technical Reports Server (NTRS)

    Robinson, J. V.; Woods, W. W.

    1950-01-01

    Mixtures of pure liquid hydrocarbons are capable of foaming. Nine hydrocarbons were mixed in pairs, in all possible combinations, and four proportions of each combination. These mixtures were sealed in glass tubes, and the foaming was tested by shaking. Mixtures of aliphatic with other aliphatic hydrocarbons, or of alkyl benzenes with other alkyl benzenes, did not foam. Mixtures of aliphatic hydrocarbons with alkyl benzenes did foam. The proportions of the mixtures greatly affected the foaming, the maximum foaming of 12 of 20 pairs being at the composition 20 percent aliphatic hydrocarbon, 80 percent alkyl benzene. Six seconds was the maximum foam lifetime of any of these mixtures. Aeroshell 120 lubricating oil was fractionated into 52 fractions and a residue by extraction with acetone in a fractionating extractor. The index of refraction, foam lifetime, color, and viscosity of these fractions were measured. Low viscosity and high index fractions were extracted first. The viscosity of the fractions extracted rose and the index decreased as fractionation proceeded. Foam lifetimes and color were lowest in the middle fractions. Significance is attached to the observation that none of the foam lifetimes of the fractions or residue is as high as the foam lifetime of the original Aeroshell, indicating that the foaming is not due to a particular foaming constituent, but rather to the entire mixture.

  16. Estrogenic activity of UV filter mixtures.

    PubMed

    Kunz, Petra Y; Fent, Karl

    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 hERalpha agonists, for their estrogenic activity in equieffective mixtures in a recombinant yeast assay carrying the human estrogen receptor alpha (hERalpha). 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 (CA) and independent action (IA) model. Most binary mixtures comprising of pure hERalpha 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 hERalpha 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. PMID:17027055

  17. Estrogenic activity of UV filter mixtures

    SciTech Connect

    Kunz, Petra Y. . E-mail: petra.kunz@fhnw.ch; Fent, Karl . 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. Viscosity of multicomponent partially ionized gas mixtures

    NASA Astrophysics Data System (ADS)

    Armaly, B. F.; Sutton, K.

    1980-07-01

    An approximate method is proposed for predicting the viscosity of partially ionized gas mixtures. This technique expresses the viscosity of a mixture in terms of the viscosities of the individual pure components, is simple in form, and does not require large computer run times or storage. Thus, the technique is suitable for use with complex flowfields and heat-transfer calculations. Results for gas mixtures which are representative of the atmospheres of Jupiter, Earth, and Venus, are presented and it is shown that the results compare favorably with detailed kinetic-theory analyses.

  19. APPARATUS FOR HANDLING MIXTURES OF SOLID MATERIALS

    DOEpatents

    Hubbell, J.P.

    1959-08-25

    An apparatus is described for handling either a mixture of finely subdivided materials or a single material requiring a compacting action thereon preparatory to a chemical reducing process carried out in a crucible container. The apparatus is designed to deposit a mixture of dust-forming solid materials in a container while confining the materials against escape into the surrounding atmosphere. A movable filling tube, having a compacting member, is connected to the container and to a covered hopper receiving the mixture of materials. The filling tube is capable of reciprocating in the container and their relative positions are dependent upon the pressure established upon the material by the compacting member.

  20. Nearly Azeotropic Mixtures To Replace Refrigerant 12

    NASA Technical Reports Server (NTRS)

    Jones, Jack A.

    1992-01-01

    Number of nearly azeotropic fluid mixtures have saturation pressures similar to Refrigerant 12 while being about 2 percent as damaging to ozone layer. Five mixtures of R134a, R152a, R124, and R142b have low boiling-point spreads, low toxicity, and low ozone-damaging capability, are nonflammable, and more compatible with conventional oils than R134a. Pressure of combinations nearly equal to R12, and mixtures may be good "drop-in substitutes". Overall composition not altered by leakage. Usable in commercial, automotive, and household refrigerators and air conditioners.

  1. Solidification phenomena of binary organic mixtures

    NASA Technical Reports Server (NTRS)

    Chang, K.

    1982-01-01

    The coalescence rates and motion of liquid bubbles in binary organic mixtures were studied. Several factors such as temperature gradient, composition gradient, interfacial tension, and densities of the two phases play important roles in separation of phases of immiscible liquids. An attempt was made to study the effect of initial compositions on separation rates of well-dispersed organic mixtures at different temperatures and, ultimately, on the homogeneity of solidification of the immiscible binary organic liquids. These organic mixtures serve as models for metallic pseudo binary systems under study. Two specific systems were investigated: ethyl salicylate - diethyl glycol and succinonitrile - water.

  2. Quantiles for Finite Mixtures of Normal Distributions

    ERIC Educational Resources Information Center

    Rahman, Mezbahur; Rahman, Rumanur; Pearson, Larry M.

    2006-01-01

    Quantiles for finite mixtures of normal distributions are computed. The difference between a linear combination of independent normal random variables and a linear combination of independent normal densities is emphasized. (Contains 3 tables and 1 figure.)

  3. Transcriptional responses to complex mixtures - A review

    EPA Science Inventory

    Exposure of people to hazardous compounds is primarily through complex environmental mixtures, those that occur through media such as air, soil, water, food, cigarette smoke, and combustion emissions. Microarray technology offers the ability to query the entire genome after expos...

  4. Assessing exposures to inhaled complex mixtures.

    PubMed Central

    Leaderer, B P; Lioy, P J; Spengler, J D

    1993-01-01

    In the course of daily activities, individuals spend varying amounts of time in different spaces where they are exposed to a complex mixture of gas, vapor, and particulate contaminants. The term complex is used in this paper to refer to binary mixtures as well as truly complex mixtures of three or more constituents. The diversity of the environments where pollution may occur, the number of pollutants that may be present, and the nature of the activity in the environment combine to pose a challenge to investigators of the health effects of air pollutants. This article discusses several methods of measuring or assessing exposure to complex mixture air contaminants that include time-activity assessments, personal monitoring, biomarkers of exposure, and microenvironmental models that can be employed singly or in combination in a protocol for exposure assessment. The use of nested designs, involving more intensive data collection from samples or subjects, is also considered. PMID:8206025

  5. Isolation of alkaline mutagens from complex mixtures

    SciTech Connect

    Ho, C.H.; Guerin, M.R.; Clark, B.R.; Rao, T.K.; Epler, J.L.

    1981-05-01

    A method for the preparative-scale enrichment of alkaline mutagens from complex natural and anthropogenic mixtures is described. Mutagenic alkaline fractions were isolated from cigarette smoke, crude petroleum, and petroleum substitutes derived from coal and shale.

  6. 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

  7. Predicting skin permeability from complex chemical mixtures

    SciTech Connect

    Riviere, Jim E. . E-mail: Jim_Riviere@ncsu.edu; 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 {sub p} = c + mMF + a{sigma}{alpha} {sub 2} {sup H} + b{sigma}{beta} {sub 2} {sup H} + s{pi} {sub 2} {sup H} + rR {sub 2} + vV {sub x} where {sigma}{alpha} {sub 2} {sup H} is the hydrogen-bond donor acidity, {sigma}{beta} {sub 2} {sup H} is the hydrogen-bond acceptor basicity, {pi} {sub 2} {sup H} is the dipolarity/polarizability, R {sub 2} represents the excess molar refractivity, and V {sub 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 {sub 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, R{sup 2} for absorption was 0.62. With the MF, correlations increased up to 0.78. Parameters correlated to the MF include refractive

  8. Structure and dynamics of biphasic colloidal mixtures.

    PubMed

    Mohraz, Ali; Weeks, Eric R; Lewis, Jennifer A

    2008-06-01

    We investigate the structure and dynamics of biphasic colloidal mixtures composed of coexisting attractive and repulsive microspheres by confocal microscopy. Attractive gels formed in the presence of repulsive microspheres are more spatially homogeneous and, on average, are both more locally tenuous and have fewer large voids than their unary counterparts. The repulsive microspheres within these mixtures display heterogeneous dynamics, with some species exhibiting freely diffusive Brownian motion while others are trapped within the gel network during aggregation. PMID:18643205

  9. Iron (III)/multiacrylate-based holographic mixtures

    NASA Astrophysics Data System (ADS)

    Lucchetta, D. E.; Nucara, L.; Criante, L.; Simoni, F.; Boni, A.; Xu, Ji-Hua; Bizzarri, R.; Castagna, R.

    2013-11-01

    We propose an holographic mixture, based on a nonconventional photoinitiator mixed with an acrylate monomer, in which high resolution thick holographic gratings are written. The used mixture that preferably works at UV and Blue-visible wavelengths shows many interesting features, such as high post-polymerization transparency, high writing resolution, and high angular selectivity. The information is permanently storable. Standard experimental techniques have been used to characterize the physical properties of the written gratings.

  10. Flash evaporation of liquid monomer particle mixture

    DOEpatents

    Affinito, John D.; Darab, John G.; Gross, Mark E.

    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.

  11. Thermodynamics of wax precipitation in petroleum mixtures

    SciTech Connect

    Firoozabadi, A.; Lira-Galeana, C.L.; Prausnitz, J.M.

    1995-12-01

    A thermodynamic framework is developed for calculating wax precipitation in petroleum mixtures over a wide temperature range. The framework assumes that the precipitated wax consists of several solid phases; each solid-phase is described as a pure component or pseudocomponent which does not mix with other solid phases. Liquid-phase properties are obtained from an equation of state. Calculated wax precipitation data are in excellent agreement with experimental results for binary and multicomponent hydrocarbon mixtures, including petroleum.

  12. Thermodynamics of wax precipitation in petroleum mixtures

    SciTech Connect

    Lira-Galeana, C.; Firoozabadi, A.; Prausnitz, J.M. |

    1996-01-01

    A thermodynamic framework is developed for calculating wax precipitation in petroleum mixtures over a wide temperature range. The framework uses the experimentally supported assumption that precipitated wax consists of several solid phases; each solid phase is described as a pure component or pseudocomponent that does not mix with other solid phases. Liquid-phase properties are obtained from an equation of state. Calculated wax-precipitation data are in excellent agreement with experimental results for binary and multicomponent hydrocarbon mixtures, including petroleum.

  13. 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.

  14. Diffusion method of seperating gaseous mixtures

    DOEpatents

    Pontius, Rex B.

    1976-01-01

    A method of effecting a relatively large change in the relative concentrations of the components of a gaseous mixture by diffusion which comprises separating the mixture into heavier and lighter portions according to major fraction mass recycle procedure, further separating the heavier portions into still heavier subportions according to a major fraction mass recycle procedure, and further separating the lighter portions into still lighter subportions according to a major fraction equilibrium recycle procedure.

  15. Homogeneous cooling of mixtures of particle shapes

    NASA Astrophysics Data System (ADS)

    Hidalgo, R. C.; Serero, D.; Pöschel, T.

    2016-07-01

    In this work, we examine theoretically the cooling dynamics of binary mixtures of spheres and rods. To this end, we introduce a generalized mean field analytical theory, which describes the free cooling behavior of the mixture. The relevant characteristic time scale for the cooling process is derived, depending on the mixture composition and the aspect ratio of the rods. We simulate mixtures of spherocylinders and spheres using a molecular dynamics algorithm implemented on graphics processing unit (GPU) architecture. We systematically study mixtures composed of spheres and rods with several aspect ratios and varying the mixture composition. A homogeneous cooling state, where the time dependence of the system's intensive variables occurs only through a global granular temperature, is identified. We find cooling dynamics in excellent agreement with Haff's law, when using an adequate time scale. Using the scaling properties of the homogeneous cooling dynamics, we estimated numerically the efficiency of the energy interchange between rotational and translational degrees of freedom for collisions between spheres and rods.

  16. Relationship inference based on DNA mixtures.

    PubMed

    Kaur, Navreet; Bouzga, Mariam M; Dørum, Guro; Egeland, Thore

    2016-03-01

    Today, there exists a number of tools for solving kinship cases. But what happens when information comes from a mixture? DNA mixtures are in general rarely seen in kinship cases, but in a case presented to the Norwegian Institute of Public Health, sample DNA was obtained after a rape case that resulted in an unwanted pregnancy and abortion. The only available DNA from the fetus came in form of a mixture with the mother, and it was of interest to find the father of the fetus. The mother (the victim), however, refused to give her reference data and so commonly used methods for paternity testing were no longer applicable. As this case illustrates, kinship cases involving mixtures and missing reference profiles do occur and make the use of existing methods rather inconvenient. We here present statistical methods that may handle general relationship inference based on DNA mixtures. The basic idea is that likelihood calculations for mixtures can be decomposed into a series of kinship problems. This formulation of the problem facilitates the use of kinship software. We present the freely available R package relMix which extends on the R version of Familias. Complicating factors like mutations, silent alleles, and θ-correction are then easily handled for quite general family relationships, and are included in the statistical methods we develop in this paper. The methods and their implementations are exemplified on the data from the rape case. PMID:26541994

  17. Phase equilibria for complex fluid mixtures

    SciTech Connect

    Prausnitz, J.M.

    1983-04-01

    After defining complex mixtures, attention is given to the canonical procedure used for the thermodynamics of fluid mixtures: first, we establish a suitable, idealized reference system and then we establish a perturbation (or excess function) which corrects the idealized system for real behavior. For complex mixtures containing identified components (e.g. alcohols, ketones, water) discussion is directed at possible techniques for extending to complex mixtures our conventional experience with reference systems and perturbations for simple mixtures. Possible extensions include generalization of the quasi-chemical approximation (local compositions) and superposition of chemical equilibria (association and solvation) on a physical equation of state. For complex mixtures containing unidentified components (e.g. coal-derived fluids), a possible experimental method is suggested for characterization; conventional procedures can then be used to calculate phase equilibria using the concept of pseudocomponents whose properties are given by the characterization data. Finally, as an alternative to the pseudocomponent method, a brief introduction is given to phase-equilibrium calculations using continuous thermodynamics.

  18. Novel anisole mixture and gasoline containing the same

    DOEpatents

    Singerman, Gary M.

    1982-01-26

    A novel anisole mixture containing anisole and a mixture of alkyl anisoles and liquid hydrocarbon fuels containing said novel anisole mixture in an amount sufficient to increase the octane number of said liquid fuel composition.

  19. 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.

  20. Deconvolution of spectra for intimate mixtures

    NASA Technical Reports Server (NTRS)

    Mustard, John F.; Pieters, Carle M.; Pratt, Stephen F.

    1987-01-01

    Visible to near infrared reflectance spectra of macroscopic mixtures have been shown to be linear combinations of the reflections of the pure mineral components in the mixture. However, for microscopic mixtures the mixing systematics are in general nonlinear. The systematics may be linearized by conversion of reflectance to single scattering albedo (w), where the equations which relate reflectance to w depend on the method of data collection. Several proposed mixing models may be used to estimate mineral abundances from the reflectance spectra of intimate mixtures. These models are summarized and a revised model is presented. A noniterative (linear) least squares approach was used for curve fitting and the data, measured as bi-directional reflectance with incidence and emergence angles of 30 and 0 deg were converted to w by a simplified version of Hapke's equation for bi-directional reflectance. This model was tested with two mixture series composed of 45 to 75 micron particles: an anorthite-enstatite series and an olivine-magnetite series. The data indicate that the simplified Hapke's equation may be used to convolve reflectance spectra into mineral abundances if appropriate endmembers are known or derived from other techniques. For surfaces that contain a significant component of very low albedo material, a somewhat modified version of this technique will need to be developed. Since the abundances are calculated using a noniterative approach, the application of this method is especially efficient for large spectral data sets, such as those produced by mapping spectrometers.

  1. Predicting phase behavior in multicomponent mixtures.

    PubMed

    Jacobs, William M; Frenkel, Daan

    2013-07-14

    Mixtures with a large number of components can undergo phase transitions of a hybrid character, with both condensation and demixing contributions. We describe a robust Monte Carlo simulation method for calculating phase coexistence in multicomponent mixtures. We use this approach to study the phase behavior of lattice models of multicomponent mixtures with strongly varying pair interactions. Such a system can be thought of as a simplified model of the cytosol, with both specific and nonspecific interactions. We show that mapping a multicomponent mixture onto an approximately equivalent one-component system yields both upper and lower bounds on the maximum solute volume fraction of a stable, homogeneous phase. By following the minimum excess-free-energy path from the dilute phase free-energy minimum, we predict the difference in composition between the condensed and dilute phases at the boundary of the homogeneous phase. We find that this "direction" of phase separation rarely aligns with the dominant direction of density fluctuations in the dilute phase. We also show that demixing transitions tend to lower the maximum solute volume fraction at which the homogeneous phase is stable. By considering statistical ensembles of mixtures with random interactions, we show that the demixing contribution to phase separation is self-averaging and dependent only on the mean and variance of the distribution of interactions. PMID:23862930

  2. Relativistic mixtures of charged and uncharged particles

    SciTech Connect

    Kremer, Gilberto M.

    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. Coal-water mixture fuel burner

    DOEpatents

    Brown, T.D.; Reehl, D.P.; Walbert, G.F.

    1985-04-29

    The present invention represents an improvement over the prior art by providing a rotating cup burner arrangement for use with a coal-water mixture fuel which applies a thin, uniform sheet of fuel onto the inner surface of the rotating cup, inhibits the collection of unburned fuel on the inner surface of the cup, reduces the slurry to a collection of fine particles upon discharge from the rotating cup, and further atomizes the fuel as it enters the combustion chamber by subjecting it to the high shear force of a high velocity air flow. Accordingly, it is an object of the present invention to provide for improved combustion of a coal-water mixture fuel. It is another object of the present invention to provide an arrangement for introducing a coal-water mixture fuel into a combustion chamber in a manner which provides improved flame control and stability, more efficient combustion of the hydrocarbon fuel, and continuous, reliable burner operation. Yet another object of the present invention is to provide for the continuous, sustained combustion of a coal-water mixture fuel without the need for a secondary combustion source such as natural gas or a liquid hydrocarbon fuel. Still another object of the present invention is to provide a burner arrangement capable of accommodating a coal-water mixture fuel having a wide range of rheological and combustion characteristics in providing for its efficient combustion. 7 figs.

  4. Mixture models for distance sampling detection functions.

    PubMed

    Miller, David L; Thomas, Len

    2015-01-01

    We present a new class of models for the detection function in distance sampling surveys of wildlife populations, based on finite mixtures of simple parametric key functions such as the half-normal. The models share many of the features of the widely-used "key function plus series adjustment" (K+A) formulation: they are flexible, produce plausible shapes with a small number of parameters, allow incorporation of covariates in addition to distance and can be fitted using maximum likelihood. One important advantage over the K+A approach is that the mixtures are automatically monotonic non-increasing and non-negative, so constrained optimization is not required to ensure distance sampling assumptions are honoured. We compare the mixture formulation to the K+A approach using simulations to evaluate its applicability in a wide set of challenging situations. We also re-analyze four previously problematic real-world case studies. We find mixtures outperform K+A methods in many cases, particularly spiked line transect data (i.e., where detectability drops rapidly at small distances) and larger sample sizes. We recommend that current standard model selection methods for distance sampling detection functions are extended to include mixture models in the candidate set. PMID:25793744

  5. 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. The first author acknowledges financial support from National Counsel of Technological and Scientific Development (CNPq) and German Academic Exchange Service (DAAD).

  6. Two-fluid theory and thermodynamic properties of liquid mixtures. Application to hard-sphere mixtures

    PubMed Central

    Brandani, V.; Prausnitz, J. M.

    1982-01-01

    This paper is the second of three describing a two-fluid theory of binary liquid mixtures. The general theory presented in the preceding paper is used to derive a model for calculating thermodynamic properties of hard-sphere mixtures. Calculations indicate that desirable boundary conditions are satisfied. PMID:16593220

  7. Detailed Kinetic Modeling of Gasoline Surrogate Mixtures

    SciTech Connect

    Mehl, M; Curran, H J; Pitz, W J; Westbrook, C K

    2009-03-09

    Real fuels are complex mixtures of thousands of hydrocarbon compounds including linear and branched paraffins, naphthenes, olefins and aromatics. It is generally agreed that their behavior can be effectively reproduced by simpler fuel surrogates containing a limited number of components. In this work, a recently revised version of the kinetic model by the authors is used to analyze the combustion behavior of several components relevant to gasoline surrogate formulation. Particular attention is devoted to linear and branched saturated hydrocarbons (PRF mixtures), olefins (1-hexene) and aromatics (toluene). Model predictions for pure components, binary mixtures and multi-component gasoline surrogates are compared with recent experimental information collected in rapid compression machine, shock tube and jet stirred reactors covering a wide range of conditions pertinent to internal combustion engines. Simulation results are discussed focusing attention on the mixing effects of the fuel components.

  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. Mixtures of planetary ices at extreme conditions.

    PubMed

    Lee, Mal-Soon; Scandolo, Sandro

    2011-01-01

    The interiors of Neptune and Uranus are believed to be primarily composed of a fluid mixture of methane and water. The mixture is subjected to pressures up to several hundred gigapascal, causing the ionization of water. Laboratory and simulation studies so far have focused on the properties of the individual components. Here we show, using first-principle molecular dynamic simulations, that the properties of the mixed fluid are qualitatively different with respect to those of its components at the same conditions. We observe a pressure-induced softening of the methane-water intermolecular repulsion that points to an enhancement of mixing under extreme conditions. Ionized water causes the progressive ionization of methane and the mixture becomes electronically conductive at milder conditions than pure water, indicating that the planetary magnetic field of Uranus and Neptune may originate at shallower depths than currently assumed. PMID:21304514

  10. Ignition limits of mixtures containing carbon monoxide

    SciTech Connect

    El'natanov, A.I.; Andreeva, N.V.; Strizhevskii, I.I.

    1983-05-01

    Much attention is being given to methods of production of carbon monoxide because of the need for savings of hydrocarbon feedstocks for industrial synthesis. Besides the traditional method of production of carbon monoxide (coal gasification), it can also be extracted from industrial discharges, which contain oxygen and other gases. For safe technological recovery processes it is necessary to know the ignition limits of mixtures which contain carbon monoxide, oxygen and an inert gas. The available data are quite limited: the ignition limits of mixtures of carbon monoxide with air or oxygen and also with air in which part of the nitrogen has been replaced by carbon dioxide. For this reason, a study was undertaken of the ignition limits of mixtures of carbon monoxide and air with carbon dioxide and argon - as substances having quite varied heat value - over a broad range.

  11. Mutation spectra of complex environmental mixtures

    SciTech Connect

    DeMarini, D.M.

    1997-10-01

    Bioassay-directed chemical analysis of complex environmental mixtures has indicated that much of the genotoxic activity of mixtures is due to the presence of one or a few classes or chemicals within the mixture. We have extended this observation to the molecular level by using colony probe hybridization and PCR/DNA sequence analysis to determine the mutation spectra of {approximately}8,000 revertants induced by a variety of complex mixtures and their chemical fractions in TA100 and TA98 of Salmonella. For urban air, >80% of mutagenic activity was due to a base/neutral fraction that contained primarily PAHs. The mutation spectrum induced by unfractionated urban air was not significantly different from that produced by a model PAH, B(a)P. The mutation spectrum induced by organic extracts of chlorinated drinking water were similar to those produced by the chlorinated furanone MX, which accounted for {approximately}20% of the mutagenic activity of the samples. The base/neutral fraction of municipal waste incinerator emissions accounted for the primary class of mutations induced by the emissions, and a polar neutral fraction accounted for the secondary class of mutations induced by the emissions. The primary class of mutations induced by cigarette smoke condensate in TA100 (GC {yields} TA) is also the primary class of mutations in the p53 gene of lung tumors of cigarette smokers. These results confirm at the molecular level that the mutations induced by a complex mixture reflect the dominance of one or a few classes of chemicals within the mixture.

  12. 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.

  13. Transcriptional responses to complex mixtures: a review.

    PubMed

    Sen, Banalata; Mahadevan, Brinda; DeMarini, David M

    2007-01-01

    Exposure of people to hazardous compounds is primarily through complex environmental mixtures, those that occur through media such as air, soil, water, food, cigarette smoke, and combustion emissions. Microarray technology offers the ability to query the entire genome after exposure to such an array of compounds, permitting a characterization of the biological effects of such exposures. This review summarizes the published literature on the transcriptional profiles resulting from exposure of cells or organisms to complex environmental mixtures such as cigarette smoke, diesel emissions, urban air, motorcycle exhaust, carbon black, jet fuel, and metal ore and fumes. The majority of the mixtures generally up-regulate gene expression, with heme oxygenase 1 and CYP1A1 being up-regulated by all of the mixtures. Most of the mixtures altered the expression of genes involved in oxidative stress response (OH-1, metallothioneins), immune/inflammation response (IL-1b, protein kinase), xenobiotic metabolism (CYP1A1, CYP1B1), coagulation and fibrinolysis (plasminogen activator/inhibitor), proto-oncogenes (FUS1, JUN), heat-shock response (HSP60, HSP70), DNA repair (PCNA, GADD45), structural unit of condensed DNA (Crf15Orf16, DUSP 15), and extracellular matrix degradation (MMP1, 8, 9, 11, 12). Genes involved in aldehyde metabolism, such as ALDH3, appeared to be uniquely modulated by cigarette smoke. Cigarette smoke-exposed populations have been successfully distinguished from control nonexposed populations based on the expression pattern of a subset of genes, thereby demonstrating the utility of this approach in identifying biomarkers of exposure and susceptibility. The analysis of gene-expression data at the pathway and functional level, along with a systems biology approach, will provide a more comprehensive insight into the biological effects of complex mixtures and will improve risk assessment of the same. We suggest critical components of study design and reporting that will

  14. Thermophysical Properties of Fluids and Fluid Mixtures

    SciTech Connect

    Sengers, Jan V.; Anisimov, Mikhail A.

    2004-05-03

    The major goal of the project was to study the effect of critical fluctuations on the thermophysical properties and phase behavior of fluids and fluid mixtures. Long-range fluctuations appear because of the presence of critical phase transitions. A global theory of critical fluctuations was developed and applied to represent thermodynamic properties and transport properties of molecular fluids and fluid mixtures. In the second phase of the project, the theory was extended to deal with critical fluctuations in complex fluids such as polymer solutions and electrolyte solutions. The theoretical predictions have been confirmed by computer simulations and by light-scattering experiments. Fluctuations in fluids in nonequilibrium states have also been investigated.

  15. Thermal conductivity of partially ionized gas mixtures

    NASA Astrophysics Data System (ADS)

    Armaly, B. F.; Sutton, K.

    1981-06-01

    A method is proposed for predicting the translational component of the thermal conductivity of partially ionized gas mixtures. It is approximate but simple in form and offers a significant improvement over commonly utilized approximations. It does not require large computer run times nor storage, thus it is suitable for use with complex flow fields and heat transfer calculations. Results for gas mixtures which are representative of the atmosphere of Jupiter, Earth, and Venus are presented and they compare favorably with results from detailed kinetic theory analyses.

  16. Paternity testing that involves a DNA mixture.

    PubMed

    Mortera, Julia; Vecchiotti, Carla; Zoppis, Silvia; Merigioli, Sara

    2016-07-01

    Here we analyse a complex disputed paternity case, where the DNA of the putative father was extracted from his corpse that had been inhumed for over 20 years. This DNA was contaminated and appears to be a mixture of at least two individuals. Furthermore, the mother's DNA was not available. The DNA mixture was analysed so as to predict the most probable genotypes of each contributor. The major contributor's profile was then used to compute the likelihood ratio for paternity. We also show how to take into account a dropout allele and the possibility of mutation in paternity testing. PMID:27017109

  17. Productivity, botanical composition, and nutritive value of commercial pasture mixtures

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pastures in the northeastern USA often are planted to mixtures of grasses and legumes. There is limited public sector information on the performance of commercial forage mixtures. We evaluated a range of commercial pasture mixtures to determine if the number of species in a mixture affected yield an...

  18. 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...

  19. 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.

  20. 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.

  1. A Skew-Normal Mixture Regression Model

    ERIC Educational Resources Information Center

    Liu, Min; Lin, Tsung-I

    2014-01-01

    A challenge associated with traditional mixture regression models (MRMs), which rest on the assumption of normally distributed errors, is determining the number of unobserved groups. Specifically, even slight deviations from normality can lead to the detection of spurious classes. The current work aims to (a) examine how sensitive the commonly…

  2. The Coffee-Milk Mixture Problem Revisited

    ERIC Educational Resources Information Center

    Marion, Charles F.

    2015-01-01

    This analysis of a problem that is frequently posed at professional development workshops, in print, and on the Web--the coffee-milk mixture riddle--illustrates the timeless advice of George Pólya's masterpiece on problem solving in mathematics, "How to Solve It." In his book, Pólya recommends that problems previously solved and put…

  3. Phase separations in a copolymer copolymer mixture

    NASA Astrophysics Data System (ADS)

    Zhang, Jin-Jun; Jin, Guojun; Ma, Yuqiang

    2006-01-01

    We propose a three-order-parameter model to study the phase separations in a diblock copolymer-diblock copolymer mixture. The cell dynamical simulations provide rich information about the phase evolution and structural formation, especially the appearance of onion-rings. The parametric dependence and physical reason for the domain growth of onion-rings are discussed.

  4. 2,4-/2,6-Dinitrotoluene mixture

    Integrated Risk Information System (IRIS)

    2,4 - / 2,6 - Dinitrotoluene mixture ; no CASRN Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncar

  5. Bayesian mixture analysis for metagenomic community profiling

    PubMed Central

    Morfopoulou, Sofia; Plagnol, Vincent

    2015-01-01

    Motivation: Deep sequencing of clinical samples is now an established tool for the detection of infectious pathogens, with direct medical applications. The large amount of data generated produces an opportunity to detect species even at very low levels, provided that computational tools can effectively profile the relevant metagenomic communities. Data interpretation is complicated by the fact that short sequencing reads can match multiple organisms and by the lack of completeness of existing databases, in particular for viral pathogens. Here we present metaMix, a Bayesian mixture model framework for resolving complex metagenomic mixtures. We show that the use of parallel Monte Carlo Markov chains for the exploration of the species space enables the identification of the set of species most likely to contribute to the mixture. Results: We demonstrate the greater accuracy of metaMix compared with relevant methods, particularly for profiling complex communities consisting of several related species. We designed metaMix specifically for the analysis of deep transcriptome sequencing datasets, with a focus on viral pathogen detection; however, the principles are generally applicable to all types of metagenomic mixtures. Availability and implementation: metaMix is implemented as a user friendly R package, freely available on CRAN: http://cran.r-project.org/web/packages/metaMix Contact: sofia.morfopoulou.10@ucl.ac.uk Supplementary information: Supplementary data are available at Bionformatics online. PMID:26002885

  6. Improved 02/H2 Gas Mixture Sensor

    NASA Technical Reports Server (NTRS)

    Moulthrop, L. C.

    1983-01-01

    Monitor of mixture concentrations uses catalyzed and uncatalyzed temperature probe. Sensor includes Pt-catalyzed temperature probe mounted in line with similar uncatalyzed temperature probe. Use of common temperature probes and standard, flareless, high-pressure tubefittings resulted in design conductive to installation in almost any system. Suitable for use in regenerative fuel cells, life-support systems, and other closed systems.

  7. Mixtures with relatives and linked markers.

    PubMed

    Dørum, Guro; Kling, Daniel; Tillmar, Andreas; Vigeland, Magnus Dehli; Egeland, Thore

    2016-05-01

    Mixture DNA profiles commonly appear in forensic genetics, and a large number of statistical methods and software are available for such cases. However, most of the literature concerns mixtures where the contributors are assumed unrelated and the genetic markers are unlinked. In this paper, we consider mixtures of linked markers and related contributors. If no relationships are involved, linkage can be ignored. While unlinked markers can be treated independently, linkage introduces dependencies. The use of linked markers presents statistical and computational challenges, but may also lead to a considerable increase in power since the number of markers available is much larger if we do not require the markers to be unlinked. In addition, some cases that cannot be solved with an unlimited number of unlinked autosomal markers can be solved with linked markers. We focus on two special cases of linked markers: pairs of linked autosomal markers and X-chromosomal markers. A framework is presented for calculation of likelihood ratios for mixtures with general relationships and with linkage between any number of markers. Finally, we explore the effect of linkage disequilibrium, also called allelic association, on the likelihood ratio. PMID:26614310

  8. 40 CFR 721.9540 - Polysulfide mixture.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... reporting. (1) The chemical substance identified generically as a polysulfide mixture (PMN P-93-1043) is... activities. Requirements as specified in § 721.80(p) (153,000 kg). (iii) Release to water. Requirements as.... Recordkeeping requirements specified in § 721.125 (a), (b), (c), (f), (g), (h), (i), (k) are applicable...

  9. 40 CFR 721.9540 - Polysulfide mixture.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... reporting. (1) The chemical substance identified generically as a polysulfide mixture (PMN P-93-1043) is... activities. Requirements as specified in § 721.80(p) (153,000 kg). (iii) Release to water. Requirements as.... Recordkeeping requirements specified in § 721.125 (a), (b), (c), (f), (g), (h), (i), (k) are applicable...

  10. 40 CFR 721.9540 - Polysulfide mixture.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... reporting. (1) The chemical substance identified generically as a polysulfide mixture (PMN P-93-1043) is... activities. Requirements as specified in § 721.80(p) (153,000 kg). (iii) Release to water. Requirements as.... Recordkeeping requirements specified in § 721.125 (a), (b), (c), (f), (g), (h), (i), (k) are applicable...

  11. 40 CFR 721.9540 - Polysulfide mixture.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... reporting. (1) The chemical substance identified generically as a polysulfide mixture (PMN P-93-1043) is... activities. Requirements as specified in § 721.80(p) (153,000 kg). (iii) Release to water. Requirements as.... Recordkeeping requirements specified in § 721.125 (a), (b), (c), (f), (g), (h), (i), (k) are applicable...

  12. 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.

  13. 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.

  14. 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.

  15. Modeling the chemistry of complex petroleum mixtures.

    PubMed Central

    Quann, R J

    1998-01-01

    Determining the complete molecular composition of petroleum and its refined products is not feasible with current analytical techniques because of the astronomical number of molecular components. Modeling the composition and behavior of such complex mixtures in refinery processes has accordingly evolved along a simplifying concept called lumping. Lumping reduces the complexity of the problem to a manageable form by grouping the entire set of molecular components into a handful of lumps. This traditional approach does not have a molecular basis and therefore excludes important aspects of process chemistry and molecular property fundamentals from the model's formulation. A new approach called structure-oriented lumping has been developed to model the composition and chemistry of complex mixtures at a molecular level. The central concept is to represent an individual molecular or a set of closely related isomers as a mathematical construct of certain specific and repeating structural groups. A complex mixture such as petroleum can then be represented as thousands of distinct molecular components, each having a mathematical identity. This enables the automated construction of large complex reaction networks with tens of thousands of specific reactions for simulating the chemistry of complex mixtures. Further, the method provides a convenient framework for incorporating molecular physical property correlations, existing group contribution methods, molecular thermodynamic properties, and the structure--activity relationships of chemical kinetics in the development of models. PMID:9860903

  16. Oxidative transformation of phenols in aqueous mixtures.

    PubMed

    Gianfreda, L; Sannino, F; Rao, M A; Bollag, J M

    2003-07-01

    The transformation by an oxidoreductase (a laccase from Rhus vernificera) of a mixture of four phenols (catechol, methylcatechol, m-tyrosol and hydroxytyrosol) that simulates a typical wastewater derived from an olive oil factory was investigated. Results achieved in this study confirm that laccase-mediated transformation of phenols depends on the nature and the initial concentration of the involved phenol, the time course of the reaction, and mainly, on the complexity of the phenolic incubation mixture. Actually, the four phenols each have a completely different response to enzyme action both in terms of quantitative and kinetic transformation. For example, after 24-h incubation, methylcatechol was completely removed, whereas 30% of untransformed hydroxytyrosol and catechol and more than 65% of m-tyrosol were still present in the reaction mixture. A reduction of enzyme activity occurred for all phenols after enzymatic oxidation. No correspondence between phenol transformation and disappearance of enzymatic activity was observed, thus suggesting that different mechanisms are probably involved in the laccase-mediated transformation of the four phenols. The behavior of phenols became more complex when an increasing number of phenols was present in the reaction mixture, and even more so when different concentrations of phenols were used. Competitive effects may arise when more than one phenol is present in the reaction solution and interacts with the enzyme. PMID:14509708

  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. 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...

  19. Oxidative particle mixtures for groundwater treatment

    DOEpatents

    Siegrist, Robert L.; Murdoch, Lawrence C.

    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.

  20. Superconductor precursor mixtures made by precipitation method

    DOEpatents

    Bunker, Bruce C.; Lamppa, Diana L.; Voigt, James A.

    1989-01-01

    Method and apparatus for preparing highly pure homogeneous precursor powder mixtures for metal oxide superconductive ceramics. The mixes are prepared by instantaneous precipitation from stoichiometric solutions of metal salts such as nitrates at controlled pH's within the 9 to 12 range, by addition of solutions of non-complexing pyrolyzable cations, such as alkyammonium and carbonate ions.

  1. 21 CFR 82.6 - Certifiable mixtures.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... PROVISIONALLY LISTED COLORS AND SPECIFICATIONS General Provisions § 82.6 Certifiable mixtures. (a) A batch of a... and cosmetics, if: (1) Each coal-tar color used as an ingredient in mixing such batch is from a previously certified batch and such color has not changed in composition in any manner whatever since...

  2. Investigating Population Heterogeneity With Factor Mixture Models

    ERIC Educational Resources Information Center

    Lubke, Gitta H.; Muthen, Bengt

    2005-01-01

    Sources of population heterogeneity may or may not be observed. If the sources of heterogeneity are observed (e.g., gender), the sample can be split into groups and the data analyzed with methods for multiple groups. If the sources of population heterogeneity are unobserved, the data can be analyzed with latent class models. Factor mixture models…

  3. 14 CFR 25.1147 - Mixture controls.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    .... However, if there is a separate flight engineer station with a control panel, the controls need be... controls. (a) If there are mixture controls, each engine must have a separate control. The controls must be grouped and arranged to allow— (1) Separate control of each engine; and (2) Simultaneous control of...

  4. Spinodal decomposition of chemically reactive binary mixtures.

    PubMed

    Lamorgese, A; Mauri, R

    2016-08-01

    We simulate the influence of a reversible isomerization reaction on the phase segregation process occurring after spinodal decomposition of a deeply quenched regular binary mixture, restricting attention to systems wherein material transport occurs solely by diffusion. Our theoretical approach follows a diffuse-interface model of partially miscible binary mixtures wherein the coupling between reaction and diffusion is addressed within the frame of nonequilibrium thermodynamics, leading to a linear dependence of the reaction rate on the chemical affinity. Ultimately, the rate for an elementary reaction depends on the local part of the chemical potential difference since reaction is an inherently local phenomenon. Based on two-dimensional simulation results, we express the competition between segregation and reaction as a function of the Damköhler number. For a phase-separating mixture with components having different physical properties, a skewed phase diagram leads, at large times, to a system converging to a single-phase equilibrium state, corresponding to the absolute minimum of the Gibbs free energy. This conclusion continues to hold for the critical phase separation of an ideally perfectly symmetric binary mixture, where the choice of final equilibrium state at large times depends on the initial mean concentration being slightly larger or less than the critical concentration. PMID:27627358

  5. Spinodal decomposition of chemically reactive binary mixtures

    NASA Astrophysics Data System (ADS)

    Lamorgese, A.; Mauri, R.

    2016-08-01

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

  6. 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…

  7. MixtureTree annotator: a program for automatic colorization and visual annotation of MixtureTree.

    PubMed

    Chen, Shu-Chuan; Ogata, Aaron

    2015-01-01

    The MixtureTree Annotator, written in JAVA, allows the user to automatically color any phylogenetic tree in Newick format generated from any phylogeny reconstruction program and output the Nexus file. By providing the ability to automatically color the tree by sequence name, the MixtureTree Annotator provides a unique advantage over any other programs which perform a similar function. In addition, the MixtureTree Annotator is the only package that can efficiently annotate the output produced by MixtureTree with mutation information and coalescent time information. In order to visualize the resulting output file, a modified version of FigTree is used. Certain popular methods, which lack good built-in visualization tools, for example, MEGA, Mesquite, PHY-FI, TreeView, treeGraph and Geneious, may give results with human errors due to either manually adding colors to each node or with other limitations, for example only using color based on a number, such as branch length, or by taxonomy. In addition to allowing the user to automatically color any given Newick tree by sequence name, the MixtureTree Annotator is the only method that allows the user to automatically annotate the resulting tree created by the MixtureTree program. The MixtureTree Annotator is fast and easy-to-use, while still allowing the user full control over the coloring and annotating process. PMID:25826378

  8. Hyperspectral unmixing using macroscopic and microscopic mixture models

    NASA Astrophysics Data System (ADS)

    Close, Ryan; Gader, Paul; Wilson, Joseph

    2014-01-01

    Macroscopic and microscopic mixture models and algorithms for hyperspectral unmixing are presented. Unmixing algorithms are derived from an objective function. The objective function incorporates the linear mixture model for macroscopic unmixing and a nonlinear mixture model for microscopic unmixing. The nonlinear mixture model is derived from a bidirectional reflectance distribution function for microscopic mixtures. The algorithm is designed to unmix hyperspectral images composed of macroscopic or microscopic mixtures. The mixture types and abundances at each pixel can be estimated directly from the data without prior knowledge of mixture types. Endmembers can also be estimated. Results are presented using synthetic data sets of macroscopic and microscopic mixtures and using well-known, well-characterized laboratory data sets. The unmixing accuracy of this new physics-based algorithm is compared to linear methods and to results published for other nonlinear models. The proposed method achieves the best unmixing accuracy.

  9. 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.

  10. A note on the meaning of mixture viscosity using the classical continuum theories of mixtures

    SciTech Connect

    Massoudi, Mehrdad

    2008-07-01

    In this paper we provide a brief review of the basic equations for the flow of two linearly viscous fluids using the mixture theory equations given in Atkin and Craine [R.J. Atkin, R.E. Craine, Continuum theories of mixtures: applications, J. Inst. Math. Appl. 17 (1976) 153; R.J. Atkin, R.E. Craine, Continuum theories of mixtures: basic theory and historical development, Quart. J. Mech. Appl. Math. 29 (1976) 290]. We then look at certain principles (or more accurately assumptions) due to Truesdell [C. Truesdell, Sulle basi della thermomeccanica, Rand Lincei, Series 8 22 (1957) 33–38, and 158–166] and Adkins [J.E. Adkins, Non-linear diffusion, 1. Diffusion and flow of mixtures of fluids, Philos. Trans. Roy. Soc. London A 255 (1963) 607–633; J.E. Adkins, Non-linear diffusion, 2. Constitutive equations for mixtures of isotropic fluids, Philos. Trans. Roy. Soc. London A 255 (1963) 635–648] and show that if the ‘assumption of the limiting cases’ of Adkins is to hold, then a very specific structure on the material properties of the two fluids has to be imposed. This new hypothesis provides one such condition for this requirement. An attempt is made to derive a relationship for the mixture viscosity using these ideas.

  11. Polydispersity effects in colloid-polymer mixtures.

    PubMed

    Liddle, S M; Narayanan, T; Poon, W C K

    2011-05-18

    We study phase separation and transient gelation experimentally in a mixture consisting of polydisperse colloids (polydispersity: ≈ 6%) and non-adsorbing polymers, where the ratio of the average size of the polymer to that of the colloid is ≈ 0.062. Unlike what has been reported previously for mixtures with somewhat lower colloid polydispersity (≈ 5%), the addition of polymers does not expand the fluid-solid coexistence region. Instead, we find a region of fluid-solid coexistence which has an approximately constant width but an unexpected re-entrant shape. We detect the presence of a metastable gas-liquid binodal, which gives rise to two-stepped crystallization kinetics that can be rationalized as the effect of fractionation. Finally, we find that the separation into multiple coexisting solid phases at high colloid volume fractions predicted by equilibrium statistical mechanics is kinetically suppressed before the system reaches dynamical arrest. PMID:21525554

  12. Supervised and Unsupervised Classification Using Mixture Models

    NASA Astrophysics Data System (ADS)

    Girard, S.; Saracco, J.

    2016-05-01

    This chapter is dedicated to model-based supervised and unsupervised classification. Probability distributions are defined over possible labels as well as over the observations given the labels. To this end, the basic tools are the mixture models. This methodology yields a posterior distribution over the labels given the observations which allows to quantify the uncertainty of the classification. The role of Gaussian mixture models is emphasized leading to Linear Discriminant Analysis and Quadratic Discriminant Analysis methods. Some links with Fisher Discriminant Analysis and logistic regression are also established. The Expectation-Maximization algorithm is introduced and compared to the K-means clustering method. The methods are illustrated both on simulated datasets as well as on real datasets using the R software.

  13. Acoustic composition sensor for cryogenic gas mixtures

    NASA Technical Reports Server (NTRS)

    Shakkottai, P.; Kwack, E. Y.; Luchik, T. S.; Back, L. H.

    1991-01-01

    An acoustic sensor useful for the determination of the composition of a gaseous binary mixture in cryogenic liquid spills has been characterized. One version of the instrument traps a known mixture of helium and nitrogen at ambient temperature in a tube which is interrogated by sonic pulses to determine the speed of sound and hence the composition. Experimental data shows that this sensor is quite accurate. The second version uses two unconfined microphones which sense sound pulses. Experimental data acquired during mixing when liquid nitrogen is poured into a vessel of gaseous helium is presented. Data during transient cooling of the tubular sensor containing nitrogen when the sensor is dipped into liquid nitrogen and during transient warm-up when the sensor is withdrawn are also presented. This sensor is being developed for use in the mixing of liquid cryogens with gas evolution in the simulation of liquid hydrogen/liquid oxygen explosion hazards.

  14. Excess compressibility in binary liquid mixtures.

    PubMed

    Aliotta, F; Gapiński, 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

  15. Dusty Plasma Structures in Gas Mixtures

    SciTech Connect

    Popova, D. V.; Antipov, S. N.; Petrov, O. F.; Fortov, V. E.

    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.

  16. Mixtures of maximally entangled pure states

    NASA Astrophysics Data System (ADS)

    Flores, M. M.; Galapon, E. A.

    2016-09-01

    We study the conditions when mixtures of maximally entangled pure states remain entangled. We found that the resulting mixed state remains entangled when the number of entangled pure states to be mixed is less than or equal to the dimension of the pure states. For the latter case of mixing a number of pure states equal to their dimension, we found that the mixed state is entangled provided that the entangled pure states to be mixed are not equally weighted. We also found that one can restrict the set of pure states that one can mix from in order to ensure that the resulting mixed state is genuinely entangled. Also, we demonstrate how these results could be applied as a way to detect entanglement in mixtures of the entangled pure states with noise.

  17. Experience with coal-water mixtures

    SciTech Connect

    Uhrig, R.E.

    1983-06-01

    A demonstration of coal-water mixture at Florida Power and Light's Sanford plant was a technological success, but not without some difficulty. Extensive accumulation of melted ash, and atomizer wear, made the demonstration only marginal economically. Falling oil prices in 1981-82 made the conversion to COM even less attractive. Combustion tests on the suitability of several candidate coal mixtures concluded that the quantity and characteristics of the ash in the coal is the most important variable in predicting fuel performance. An examination of the characteristics of CWM with various coal-water ratios shows that the ''water penalty'' is not as severe as believed. Yet it is NOT a foregone conclusion that CWM fuels will be economical in the future.

  18. 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.

  19. 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.

  20. 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

  1. Embedded Electronic Nose for VOC Mixture Analysis

    SciTech Connect

    Botre, B.; Gharpure, D.; Shaligram, A.

    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.

  2. 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.

  3. 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.

  4. 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.

  5. Separation of mixtures in connected channels

    NASA Astrophysics Data System (ADS)

    Glukhov, A. F.; Demin, V. A.; Putin, G. F.

    2009-01-01

    The stationary modes of thermal convection of a binary mixture in connected channels of finite height were studied experimentally and theoretically. The effects of positive and negative thermal diffusion on the convection were examined. The ranges of parameters corresponding to the modes of soft and rigid initiation of convection were determined. Vertical distributions of the temperature and concentration fields were found for various values of the thermal diffusion parameter.

  6. Toxic responses of bivalves to metal mixtures

    SciTech Connect

    Mathew, P.; Menon, N.R. )

    1992-02-01

    Although there is a growing body of information on the toxicity of individual heavy metals to economically important on the toxicity of individual heavy metals to economically important species of bivalves, literature on the lethal toxicity of metal mixtures to bivalves under controlled conditions is rather limited. In the present investigation the toxic effects of combinations of copper - mercury and copper - mercury and copper - cadmium at lethal levels of two marine bivalve species, Perna indica and Donax incarnatus, have been delineated.

  7. Instability of a solidifying binary mixture

    NASA Technical Reports Server (NTRS)

    Antar, B. N.

    1982-01-01

    An analysis is performed on the stability of a solidifying binary mixture due to surface tension variation of the free liquid surface. The basic state solution is obtained numerically as a nonstationary function of time. Due to the time dependence of the basic state, the stability analysis is of the global type which utilizes a variational technique. Also due to the fact that the basic state is a complex function of both space and time, the stability analysis is performed through numerical means.

  8. Dynamic thermodiffusion model for binary liquid mixtures.

    PubMed

    Eslamian, Morteza; Saghir, M Ziad

    2009-07-01

    Following the nonequilibrium thermodynamics approach, we develop a dynamic model to emulate thermo-diffusion process and propose expressions for estimating the thermal diffusion factor in binary nonassociating liquid mixtures. Here, we correlate the net heat of transport in thermodiffusion with parameters, such as the mixture temperature and pressure, the size and shape of the molecules, and mobility of the components, because the molecules have to become activated before they can move. Based on this interpretation, the net heat of transport of each component can be somehow related to the viscosity and the activation energy of viscous flow of the same component defined in Eyring's reaction-rate theory [S. Glasstone, K. J. Laidler, and H. Eyring, (McGraw-Hill, New York, 1941)]. This modeling approach is different from that of Haase and Kempers, in which thermodiffusion is considered as a function of the thermostatic properties of the mixture such as enthalpy. In simulating thermodiffusion, by correlating the net heat of transport with the activation energy of viscous flow, effects of the above mentioned parameters are accounted for, to some extent of course. The model developed here along with Haase-Kempers and Drickamer-Firoozabadi models linked with the Peng-Robinson equation of sate are evaluated against the experimental data for several recent nonassociating binary mixtures at various temperatures, pressures, and concentrations. Although the model prediction is still not perfect, the model is simple and easy to use, physically justified, and predicts the experimental data very good and much better than the existing models. PMID:19658691

  9. Dynamic thermodiffusion model for binary liquid mixtures

    NASA Astrophysics Data System (ADS)

    Eslamian, Morteza; Saghir, M. Ziad

    2009-07-01

    Following the nonequilibrium thermodynamics approach, we develop a dynamic model to emulate thermo-diffusion process and propose expressions for estimating the thermal diffusion factor in binary nonassociating liquid mixtures. Here, we correlate the net heat of transport in thermodiffusion with parameters, such as the mixture temperature and pressure, the size and shape of the molecules, and mobility of the components, because the molecules have to become activated before they can move. Based on this interpretation, the net heat of transport of each component can be somehow related to the viscosity and the activation energy of viscous flow of the same component defined in Eyring’s reaction-rate theory [S. Glasstone, K. J. Laidler, and H. Eyring, The Theory of Rate Processes: The Kinetics of Chemical Reactions, Viscosity, Diffusion and Electrochemical Phenomena (McGraw-Hill, New York, 1941)]. This modeling approach is different from that of Haase and Kempers, in which thermodiffusion is considered as a function of the thermostatic properties of the mixture such as enthalpy. In simulating thermodiffusion, by correlating the net heat of transport with the activation energy of viscous flow, effects of the above mentioned parameters are accounted for, to some extent of course. The model developed here along with Haase-Kempers and Drickamer-Firoozabadi models linked with the Peng-Robinson equation of sate are evaluated against the experimental data for several recent nonassociating binary mixtures at various temperatures, pressures, and concentrations. Although the model prediction is still not perfect, the model is simple and easy to use, physically justified, and predicts the experimental data very good and much better than the existing models.

  10. Endocrine activity of mycotoxins and mycotoxin mixtures.

    PubMed

    Demaegdt, Heidi; Daminet, Britt; Evrard, Annick; Scippo, Marie-Louise; Muller, Marc; Pussemier, Luc; Callebaut, Alfons; Vandermeiren, Karine

    2016-10-01

    Reporter gene assays incorporating nuclear receptors (estrogen, androgen, thyroid β and PPARγ2) have been implemented to assess the endocrine activity of 13 mycotoxins and their mixtures. As expected, zearalenone and its metabolites α-zearalenol and β- zearalenol turned out to have the strongest estrogenic potency (EC50 8,7 10-10 ± 0,8; 3,1 10-11 ± 0,5 and 1,3 10-8 ± 0,3 M respectively). The metabolite of deoxynivalenol, 3-acetyl-deoxynivalenol also had estrogenic activity (EC50 3,8 10-7 ± 1,1 M). Furthermore, most of the mycotoxins (and their mixtures) showed anti-androgenic effects (15-acetyldeoxynivalenol, 3-acetyl-deoxynivalenol and α-zearalenol with potencies within one order of magnitude of that of the reference compound flutamide). In particular, deoxynivalenol and 15-acetyl-deoxynivalenol acted as antagonists for the PPARy2 receptor. When testing mixtures of mycotoxins on the same cell systems, we showed that most of the mixtures reacted as predicted by the concentration addition (CA) theory. Generally, the CA was within the 95% confidence interval of the observed ones, only minor deviations were detected. Although these reporter gene tests cannot be directly extrapolated in vivo, they can be the basis for further research. Especially the additive effects of ZEN and its metabolites are of importance and could have repercussions in vivo. PMID:27481073

  11. Population mixture model for nonlinear telomere dynamics

    NASA Astrophysics Data System (ADS)

    Itzkovitz, Shalev; Shlush, Liran I.; Gluck, Dan; Skorecki, Karl

    2008-12-01

    Telomeres are DNA repeats protecting chromosomal ends which shorten with each cell division, eventually leading to cessation of cell growth. We present a population mixture model that predicts an exponential decrease in telomere length with time. We analytically solve the dynamics of the telomere length distribution. The model provides an excellent fit to available telomere data and accounts for the previously unexplained observation of telomere elongation following stress and bone marrow transplantation, thereby providing insight into the nature of the telomere clock.

  12. Hierarchical similarity transformations between Gaussian mixtures.

    PubMed

    Rigas, George; Nikou, Christophoros; Goletsis, Yorgos; Fotiadis, Dimitrios I

    2013-11-01

    In this paper, we propose a method to estimate the density of a data space represented by a geometric transformation of an initial Gaussian mixture model. The geometric transformation is hierarchical, and it is decomposed into two steps. At first, the initial model is assumed to undergo a global similarity transformation modeled by translation, rotation, and scaling of the model components. Then, to increase the degrees of freedom of the model and allow it to capture fine data structures, each individual mixture component may be transformed by another, local similarity transformation, whose parameters are distinct for each component of the mixture. In addition, to constrain the order of magnitude of the local transformation (LT) with respect to the global transformation (GT), zero-mean Gaussian priors are imposed onto the local parameters. The estimation of both GT and LT parameters is obtained through the expectation maximization framework. Experiments on artificial data are conducted to evaluate the proposed model, with varying data dimensionality, number of model components, and transformation parameters. In addition, the method is evaluated using real data from a speech recognition task. The obtained results show a high model accuracy and demonstrate the potential application of the proposed method to similar classification problems. PMID:24808615

  13. Safety Testing of Ammonium Nitrate Based Mixtures

    NASA Astrophysics Data System (ADS)

    Phillips, Jason; Lappo, Karmen; Phelan, James; Peterson, Nathan; Gilbert, Don

    2013-06-01

    Ammonium nitrate (AN)/ammonium nitrate based explosives have a lengthy documented history of use by adversaries in acts of terror. While historical research has been conducted on AN-based explosive mixtures, it has primarily focused on detonation performance while varying the oxygen balance between the oxidizer and fuel components. Similarly, historical safety data on these materials is often lacking in pertinent details such as specific fuel type, particle size parameters, oxidizer form, etc. A variety of AN-based fuel-oxidizer mixtures were tested for small-scale sensitivity in preparation for large-scale testing. Current efforts focus on maintaining a zero oxygen-balance (a stoichiometric ratio for active chemical participants) while varying factors such as charge geometry, oxidizer form, particle size, and inert diluent ratios. Small-scale safety testing was conducted on various mixtures and fuels. It was found that ESD sensitivity is significantly affected by particle size, while this is less so for impact and friction. Thermal testing is in progress to evaluate hazards that may be experienced during large-scale testing.

  14. Individual biotransformation rates in chlorinated aliphatic mixtures

    SciTech Connect

    Hughes, J.B.; Parkin, G.F.

    1996-02-01

    Anaerobic biotransformation of chlorinated aliphatics has been widely studied over the past decade, and anaerobic bioremediation is considered a promising technique for restoration of contaminated aquifers. Studies using batch cultures and continuously fed attached-growth systems investigated the effect of mixtures of chlorinated aliphatics on the anaerobic biotransformation rates of individual components of the mixture. Dichloromethane (DCM), chloroform (CF), and 1,1,1-trichloroethane (TCA) were selected for study because of their frequent detection in groundwater. Biotransformation of CF and TCA occurred in all systems. When CF and TCA were fed together, transformation rates for both aliphatics were lower than when fed individually. DCM generally had minor to negligible effects on the transformation of CF and TCA, but in one case, it caused a slight but statistically significant decrease in TCA transformation (p = 0.05). DCM transformation was not observed when fed individually or in mixtures to batch resting cultures, so the effect of CF and TCA on DCM transformation could not be determined.

  15. Negative Binomial Process Count and Mixture Modeling.

    PubMed

    Zhou, Mingyuan; Carin, Lawrence

    2015-02-01

    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 an 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 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:26353243

  16. Tandem mass spectrometry: analysis of complex mixtures

    SciTech Connect

    Singleton, K.E.

    1985-01-01

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

  17. Familial searching on DNA mixtures with dropout.

    PubMed

    Slooten, K

    2016-05-01

    Familial searching, the act of searching a database for a relative of an unknown individual whose DNA profile has been obtained, is usually restricted to cases where the DNA profile of that person has been unambiguously determined. Therefore, it is normally applied only with a good quality single source profile as starting point. In this article we investigate the performance of the method if applied to mixtures with and without allelic dropout, when likelihood ratios are computed with a semi-continuous (binary) model. We show that mixtures with dropout do not necessarily perform worse than mixtures without, especially if some separation between the donors is possible due to their different dropout probabilities. The familial searching true and false positive rates of mixed profiles on 15 loci are in some cases better than those of single source profiles on 10 loci. Thus, the information loss due to the fact that the person of interest's DNA has been mixed with that of other, and is affected by dropout, can be less than the loss of information corresponding to having 5 fewer loci available for a single source trace. Profiles typed on 10 autosomal loci are often involved in familial searching casework since many databases, including the Dutch one, in part consist of such profiles. Therefore, from this point of view, there seems to be no objection to extend familial searching to mixed or degraded profiles. PMID:26905597

  18. Ethane-xenon mixtures under shock conditions

    SciTech Connect

    Magyar, Rudolph J.; Root, Seth; Mattsson, Thomas; Cochrane, Kyle Robert; Flicker, Dawn G.

    2015-04-22

    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. In order 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. Furthermore, 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.

  19. Crowding in polymer-nanoparticle mixtures.

    PubMed

    Denton, Alan R

    2014-01-01

    The cell nucleus is a highly crowded environment, filled with a multicomponent, polydisperse mixture of biopolymers and nuclear bodies dispersed in a viscous solvent. With volume fractions approaching 20%, excluded-volume interactions play a key role in determining the structure, dynamics, and function of macromolecules in vivo. Under such constraints, the ensembles of macromolecular conformations can differ substantially from those prevailing in dilute solutions. Crowding thus can affect protein and RNA folding, conformational stability, and reaction kinetics, as well as phase stability of macromolecular mixtures. From the perspective of soft matter physics, this chapter reviews recent studies on crowding in polymer-nanoparticle mixtures, seeking to demonstrate the utility of simple physical models for addressing challenging issues in cell biology. The focus is on applications of free-volume theory and Monte Carlo simulation, based on geometrical models of polymers as fluctuating spheres or ellipsoids. Ideal polymer coils respond to hard-sphere crowding agents by compactifying, reducing their radius of gyration, and becoming more spherical. At sufficiently high concentrations, polymers and crowders phase-separate. The goal of this review is to identify universal principles governing macromolecular crowding and to establish a general framework for future explorations of more realistic models that may include nonsteric (e.g., electrostatic) interactions. PMID:24380592

  20. Synergy in protein-osmolyte mixtures.

    PubMed

    Rösgen, Jörg

    2015-01-01

    Virtually all taxa use osmolytes to protect cells against biochemical stress. Osmolytes often occur in mixtures, such as the classical combination of urea with TMAO (trimethylamine N-oxide) in cartilaginous fish or the cocktail of at least six different osmolytes in the kidney. The concentration patterns of osmolyte mixtures found in vivo make it likely that synergy between them plays an important role. Using statistical mechanical n-component Kirkwood-Buff theory, we show from first principles that synergy in protein-osmolyte systems can arise from two separable sources: (1) mutual alteration of protein surface solvation and (2) effects mediated through bulk osmolyte chemical activities. We illustrate both effects in a four-component system with the experimental example of the unfolding of a notch ankyrin domain in urea-TMAO mixtures, which make urea a less effective denaturant and TMAO a more effective stabilizer. Protein surface effects are primarily responsible for this synergy. The specific patterns of surface solvation point to denatured state expansion as the main factor, as opposed to direct competition. PMID:25490052

  1. Ethane-xenon mixtures under shock conditions

    DOE PAGESBeta

    Magyar, Rudolph J.; Root, Seth; Mattsson, Thomas; Cochrane, Kyle Robert; Flicker, Dawn G.

    2015-04-22

    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. In order 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. Furthermore, themore » 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.« less

  2. Ethane-xenon mixtures under shock conditions

    NASA Astrophysics Data System (ADS)

    Flicker, Dawn; Magyar, Rudolph; Root, Seth; Cochrane, Kyle; Mattsson, Thomas

    2015-06-01

    Mixtures of light and heavy elements arise in inertial confinement fusion and planetary science. We present results on the physics of molecular scale mixing through a validation study of equation of state (EOS) properties. Density functional theory molecular dynamics (DFT/QMD) at elevated-temperature and pressure is used to obtain the properties of pure xenon, ethane, and various compressed mixture compositions along their principal Hugoniots. To validate the QMD simulations, we performed high-precision shock compression experiments using Sandia's Z-Machine. A bond tracking analysis of the simulations correlates the sharp rise in the Hugoniot curve with completion of dissociation in ethane. DFT-based simulation results compare well with experimental data and are used to provide insight into the dissociation as a function of mixture composition. Interestingly, we find that the compression ratio for complete dissociation is similar for ethane, Xe-ethane, polymethyl-pentene, and polystyrene, suggesting that a limiting compression exists for C-C bonded systems. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, Security Administration under contract DE-AC04-94AL85000.

  3. 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

  4. Computational Aspects of N-Mixture Models

    PubMed Central

    Dennis, Emily B; Morgan, Byron JT; Ridout, Martin S

    2015-01-01

    The N-mixture model is widely used to estimate the abundance of a population in the presence of unknown detection probability from only a set of counts subject to spatial and temporal replication (Royle, 2004, Biometrics 60, 105–115). We explain and exploit the equivalence of N-mixture and multivariate Poisson and negative-binomial models, which provides powerful new approaches for fitting these models. We show that particularly when detection probability and the number of sampling occasions are small, infinite estimates of abundance can arise. We propose a sample covariance as a diagnostic for this event, and demonstrate its good performance in the Poisson case. Infinite estimates may be missed in practice, due to numerical optimization procedures terminating at arbitrarily large values. It is shown that the use of a bound, K, for an infinite summation in the N-mixture likelihood can result in underestimation of abundance, so that default values of K in computer packages should be avoided. Instead we propose a simple automatic way to choose K. The methods are illustrated by analysis of data on Hermann's tortoise Testudo hermanni. PMID:25314629

  5. Generalized Mixture Models for Molecular Phylogenetic Estimation

    PubMed Central

    Evans, Jason; Sullivan, Jack

    2012-01-01

    The rapidly growing availability of multigene sequence data during the past decade has enabled phylogeny estimation at phylogenomic scales. However, dealing with evolutionary process heterogeneity across the genome becomes increasingly challenging. Here we develop a mixture model approach that uses reversible jump Markov chain Monte Carlo (MCMC) estimation to permit as many distinct models as the data require. Each additional model considered may be a fully parametrized general time-reversible model or any of its special cases. Furthermore, we expand the usual proposal mechanisms for topology changes to permit hard polytomies (i.e., zero-length internal branches). This new approach is implemented in the Crux software toolkit. We demonstrate the feasibility of using reversible jump MCMC on mixture models by reexamining a well-known 44-taxon mammalian data set comprising 22 concatenated genes. We are able to reproduce the results of the original analysis (with respect to bipartition support) when we make identical assumptions, but when we allow for polytomies and/or use data-driven mixture model estimation, we infer much lower bipartition support values for several key bipartitions. PMID:21873377

  6. Precursors in gas-liquid mixtures

    NASA Astrophysics Data System (ADS)

    Gasenko, V. G.; Gorelik, R. S.; Nakoryakov, V. E.; Timkin, L. S.

    2013-10-01

    Two types of precursors propagating at the speed of sound in a pure liquid have been revealed in the experiments on the evolution of pressure pulses in a gas-liquid mixture; at the same time, the main pressure pulse propagates at a low equilibrium speed of sound and its evolution is described by the Burgers-Korteweg-de Vries equation. The first high-frequency precursor is a complete analog of a classical Sommerfeld precursor, because the resonance dispersion equation for a bubble mixture coincides with that for insulators in the Lorentz model, and oscillates at a frequency close to the "plasma frequency." The second low-frequency precursor has been revealed in this work. The frequency of the low-frequency precursor is close to the resonance frequency of pulsations of bubbles, which is almost an order of magnitude lower than the frequency of the high-frequency precursor. The low-frequency precursor has a much larger amplitude of pulsations and smaller damping and is not described within the homogeneous model of the gas-liquid mixture. The observed phenomenon of low-frequency precursors has been explained within a simple heterogeneous model of a bubble liquid.

  7. Non-Genomic Effects of Xenoestrogen Mixtures

    PubMed Central

    Viñas, René; Jeng, Yow-Jiun; Watson, Cheryl S.

    2012-01-01

    Xenoestrogens (XEs) are chemicals derived from a variety of natural and anthropogenic sources that can interfere with endogenous estrogens by either mimicking or blocking their responses via non-genomic and/or genomic signaling mechanisms. Disruption of estrogens’ actions through the less-studied non-genomic pathway can alter such functional end points as cell proliferation, peptide hormone release, catecholamine transport, and apoptosis, among others. Studies of potentially adverse effects due to mixtures and to low doses of endocrine-disrupting chemicals have recently become more feasible, though few so far have included actions via the non-genomic pathway. Physiologic estrogens and XEs evoke non-monotonic dose responses, with different compounds having different patterns of actions dependent on concentration and time, making mixture assessments all the more challenging. In order to understand the spectrum of toxicities and their mechanisms, future work should focus on carefully studying individual and mixture components across a range of concentrations and cellular pathways in a variety of tissue types. PMID:23066391

  8. Statistical mechanical theory of fluid mixtures

    NASA Astrophysics Data System (ADS)

    Zhao, Yueqiang; Wu, Zhengming; Liu, Weiwei

    2014-01-01

    A general statistical mechanical theory of fluid mixtures (liquid mixtures and gas mixtures) is developed based on the statistical mechanical expression of chemical potential of components in the grand canonical ensemble, which gives some new relationships between thermodynamic quantities (equilibrium ratio Ki, separation factor α and activity coefficient γi) and ensemble average potential energy u for one molecule. The statistical mechanical expressions of separation factor α and activity coefficient γi derived in this work make the fluid phase equilibrium calculations can be performed by molecular simulation simply and efficiently, or by the statistical thermodynamic approach (based on the saturated-vapor pressure of pure substance) that does not need microscopic intermolecular pair potential functions. The physical meaning of activity coefficient γi in the liquid phase is discussed in detail from a viewpoint of molecular thermodynamics. The calculated Vapor-Liquid Equilibrium (VLE) properties of argon-methane, methanol-water and n-hexane-benzene systems by this model fit well with experimental data in references, which indicates that this model is accurate and reliable in the prediction of VLE properties for small, large and strongly associating molecules; furthermore the statistical mechanical expressions of separation factor α and activity coefficient γi have good compatibility with classical thermodynamic equations and quantum mechanical COSMO-SAC approach.

  9. Dual-water mixture fuel burner

    DOEpatents

    Brown, Thomas D.; Reehl, Douglas P.; Walbert, Gary F.

    1986-08-05

    A coal-water mixture (CWM) burner includes a conically shaped rotating cup into which fuel comprised of coal particles suspended in a slurry is introduced via a first, elongated inner tube coupled to a narrow first end portion of the cup. A second, elongated outer tube is coaxially positioned about the first tube and delivers steam to the narrow first end of the cup. The fuel delivery end of the inner first tube is provided with a helical slot on its lateral surface for directing the CWM onto the inner surface of the rotating cup in the form of a uniform, thin sheet which, under the influence of the cup's centrifugal force, flows toward a second, open, expanded end portion of the rotating cup positioned immediately adjacent to a combustion chamber. The steam delivered to the rotating cup wets its inner surface and inhibits the coal within the CWM from adhering to the rotating cup. A primary air source directs a high velocity air flow coaxially about the expanded discharge end of the rotating cup for applying a shear force to the CWM in atomizing the fuel mixture for improved combustion. A secondary air source directs secondary air into the combustion chamber adjacent to the outlet of the rotating cup at a desired pitch angle relative to the fuel mixture/steam flow to promote recirculation of hot combustion gases within the ignition zone for increased flame stability.

  10. Bridging environmental mixtures and toxic effects

    PubMed Central

    Allan, Sarah E.; Smith, Brian W.; Tanguay, Robert L.; Anderson, Kim A.

    2012-01-01

    BRIDGES is a bioanalytical tool that combines passive sampling with the embryonic zebrafish developmental toxicity bioassay to provide a quantitative measure of the toxicity of bioavailable complex mixtures. Passive sampling devices (PSDs), which sequester and concentrate bioavailable organic contaminants from the environment, were deployed in the Willamette and Columbia Rivers within and outside of the Portland Harbor Superfund site in Portland, Oregon. Six sampling events were conducted in the summer and fall of 2009 and 2010. PSD extracts were analyzed for polycyclic aromatic hydrocarbon (PAH) compounds and screened for 1201 chemicals of concern using deconvolution reporting software. The developmental toxicity of the extracts was analyzed using the embryonic zebrafish bioassay. BRIDGES provided site-specific, temporally resolved information about environmental contaminant mixtures and their toxicity. Multivariate modeling approaches were applied to paired chemical and toxic effects data sets to help unravel chemistry-toxicity associations. Modeling demonstrated a significant correlation between PAH concentrations and the toxicity of the samples and identified a subset of PAH analytes that were the most highly correlated with observed toxicity. Although this research highlights the complexity of discerning specific bioactive compounds in complex mixtures, it demonstrates methods for associating toxic effects with chemical characteristics of environmental samples. PMID:23001962

  11. 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.

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

    PubMed

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

    1996-01-01

    Monsanto employs several pragmatic approaches for evaluating the toxicity of mixtures. These approaches are similar to those recommended by many national and international agencies. When conducting hazard and risk assessments, priority is always given to using data collected directly on the mixture of concern. To provide an example of the first tier of evaluation, actual data on acute respiratory irritation studies on mixtures were evaluated to determine whether the principle of additivity was applicable to the mixture evaluated. If actual data on the mixture are unavailable, extrapolation across similar mixtures is considered. Because many formulations are quite similar in composition, the toxicity data from one mixture can be extended to a closely related mixture in a scientifically justifiable manner. An example of a family of products where such extrapolations have been made is presented to exemplify this second approach. Lastly, if data on similar mixtures are unavailable, data on component fractions are used to predict the toxicity of the mixture. In this third approach, process knowledge and scientific judgement are used to determine how the known toxicological properties of the individual fractions affect toxicity of the mixture. Three examples of plant effluents where toxicological data on fractions were used to predict the toxicity of the mixture are discussed. The results of the analysis are used to discuss the predictive value of each of the above mentioned toxicological approaches for evaluating chemical mixtures. PMID:9119327

  13. Separation of gas mixtures by supported complexes

    SciTech Connect

    Nelson, D.A.; Lilga, M.A.; Hallen, R.T.; Lyke, S.E.

    1986-08-01

    The goal of this program is to determine the feasibility of solvent-dissolved coordination complexes for the separation of gas mixtures under bench-scale conditions. In particular, mixtures such as low-Btu gas are examined for CO and H/sub 2/ separation. Two complexes, Pd/sub 2/(dpm)/sub 2/Br/sub 2/ and Ru(CO)/sub 2/(PPh/sub 3/)/sub 3/, were examined in a bench-scale apparatus for the separation of binary (CO-N/sub 2/ or H/sub 2/-N/sub 2/) and quinary (H/sub 2/, CO, CO/sub 2/, CH/sub 4/, and N/sub 2/) mixtures. The separation of CO-N/sub 2/ was enhanced by the presence of the palladium complex in the 1,1,2-trichloroethane (TCE) solvent, especially at high gas and low liquid rates. The five-component gas mixture separation with the palladium complex in TCE provided quite unexpected results based on physical solubility and chemical coordination. The complex retained CO, while the solvent retained CO/sub 2/, CH/sub 4/, and N/sub 2/ to varying degrees. This allowed the hydrogen content to be enhanced due to its low solubility in TCE and inertness to the complex. Thus, a one-step, hydrogen separation can be achieved from gas mixtures with compositions similar to that of oxygen-blown coal gas. A preliminary economic evaluation of hydrogen separation was made for a system based on the palladium complex. The palladium system has a separation cost of 50 to 60 cents/MSCF with an assumed capital investment of $1.60/MSCF of annual capacity charged at 30% per year. This assumes a 3 to 4 year life for the complex. Starting with a 90% hydrogen feed, PSA separation costs are in the range of 30 to 50 cents/MSCF. The ruthenium complex was not as successful for hydrogen or carbon monoxide separation due to unfavorable kinetics. The palladium complex was found to strip hydrogen gas from H/sub 2/S. The complex could be regenerated with mild oxidants which removed the sulfur as SO/sub 2/. 24 refs., 26 figs., 10 tabs.

  14. Complex mixtures, complex responses: Assessing pharmaceutical mixtures using field and laboratory approaches.

    PubMed

    Schoenfuss, Heiko L; Furlong, Edward T; Phillips, Pat J; Scott, Tia-Marie; Kolpin, Dana W; Cetkovic-Cvrlje, Marina; Lesteberg, Kelsey E; Rearick, Daniel C

    2016-04-01

    Pharmaceuticals are present in low concentrations (<100 ng/L) in most municipal wastewater effluents but may be elevated locally because of factors such as input from pharmaceutical formulation facilities. Using existing concentration data, the authors assessed pharmaceuticals in laboratory exposures of fathead minnows (Pimephales promelas) and added environmental complexity through effluent exposures. In the laboratory, larval and mature minnows were exposed to a simple opioid mixture (hydrocodone, methadone, and oxycodone), an opioid agonist (tramadol), a muscle relaxant (methocarbamol), a simple antidepressant mixture (fluoxetine, paroxetine, venlafaxine), a sleep aid (temazepam), or a complex mixture of all compounds. Larval minnow response to effluent exposure was not consistent. The 2010 exposures resulted in shorter exposed minnow larvae, whereas the larvae exposed in 2012 exhibited altered escape behavior. Mature minnows exhibited altered hepatosomatic indices, with the strongest effects in females and in mixture exposures. In addition, laboratory-exposed, mature male minnows exposed to all pharmaceuticals (except the selective serotonin reuptake inhibitor mixture) defended nest sites less rigorously than fish in the control group. Tramadol or antidepressant mixture exposure resulted in increased splenic T lymphocytes. Only male minnows exposed to whole effluent responded with increased plasma vitellogenin concentrations. Female minnows exposed to pharmaceuticals (except the opioid mixture) had larger livers, likely as a compensatory result of greater prominence of vacuoles in liver hepatocytes. The observed alteration of apical endpoints central to sustaining fish populations confirms that effluents containing waste streams from pharmaceutical formulation facilities can adversely impact fish populations but that the effects may not be temporally consistent. The present study highlights the importance of including diverse biological endpoints spanning

  15. Complex mixtures, complex responses: Assessing pharmaceutical mixtures using field and laboratory approaches

    USGS Publications Warehouse

    Schoenfuss, Heiko L.; Furlong, Edward T.; Phillips, Patrick J.; Scott, Tia-Marie; Kolpin, Dana W.; Cetkovic-Cvrlje, Marina; Lesteberg, Kelsey E.; Rearick, Daniel C.

    2016-01-01

    Pharmaceuticals are present in low concentrations (<100 ng/L) in most municipal wastewater effluents but may be elevated locally because of factors such as input from pharmaceutical formulation facilities. Using existing concentration data, the authors assessed pharmaceuticals in laboratory exposures of fathead minnows (Pimephales promelas) and added environmental complexity through effluent exposures. In the laboratory, larval and mature minnows were exposed to a simple opioid mixture (hydrocodone, methadone, and oxycodone), an opioid agonist (tramadol), a muscle relaxant (methocarbamol), a simple antidepressant mixture (fluoxetine, paroxetine, venlafaxine), a sleep aid (temazepam), or a complex mixture of all compounds. Larval minnow response to effluent exposure was not consistent. The 2010 exposures resulted in shorter exposed minnow larvae, whereas the larvae exposed in 2012 exhibited altered escape behavior. Mature minnows exhibited altered hepatosomatic indices, with the strongest effects in females and in mixture exposures. In addition, laboratory-exposed, mature male minnows exposed to all pharmaceuticals (except the selective serotonin reuptake inhibitor mixture) defended nest sites less rigorously than fish in the control group. Tramadol or antidepressant mixture exposure resulted in increased splenic T lymphocytes. Only male minnows exposed to whole effluent responded with increased plasma vitellogenin concentrations. Female minnows exposed to pharmaceuticals (except the opioid mixture) had larger livers, likely as a compensatory result of greater prominence of vacuoles in liver hepatocytes. The observed alteration of apical endpoints central to sustaining fish populations confirms that effluents containing waste streams from pharmaceutical formulation facilities can adversely impact fish populations but that the effects may not be temporally consistent. The present study highlights the importance of including diverse biological endpoints spanning

  16. REFLEAK: NIST Leak/Recharge Simulation Program for Refrigerant Mixtures

    National Institute of Standards and Technology Data Gateway

    SRD 73 NIST REFLEAK: NIST Leak/Recharge Simulation Program for Refrigerant Mixtures (PC database for purchase)   REFLEAK estimates composition changes of zeotropic mixtures in leak and recharge processes.

  17. 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.

  18. A stochastic approximation algorithm for estimating mixture proportions

    NASA Technical Reports Server (NTRS)

    Sparra, J.

    1976-01-01

    A stochastic approximation algorithm for estimating the proportions in a mixture of normal densities is presented. The algorithm is shown to converge to the true proportions in the case of a mixture of two normal densities.

  19. RESULTS OF IPCS COLLABORATIVE STUDY ON COMPLEX MIXTURES

    EPA Science Inventory

    The International Programme on Chemical Safety (IPCS) sponsored a collaborative study to examine the intra- and interlaboratory variation associated with the preparation and bioassay of complex chemical mixtures. The mixtures selected were National Institute of Standards and Tech...

  20. 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...

  1. Chemical Mixture Risk Assessment Additivity-Based Approaches

    EPA Science Inventory

    Powerpoint presentation includes additivity-based chemical mixture risk assessment methods. Basic concepts, theory and example calculations are included. Several slides discuss the use of "common adverse outcomes" in analyzing phthalate mixtures.

  2. Liquid class predictor for liquid handling of complex mixtures

    DOEpatents

    Seglke, Brent W.; Lekin, Timothy P.

    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.

  3. Noise and crossover exponents in conductor-insulator mixtures and superconductor-conductor mixtures

    SciTech Connect

    Tremblay, R.R. ); Albinet, G. ); Tremblay, A.S. )

    1992-01-01

    The resistance noise of random conductor-insulator mixtures is studied in the case where the insulators have a small but finite conductance. The conductance noise of superconductor-conductor mixtures is similarly studied when the superconductors have a small but finite resistance. The Migdal-Kadanoff renormalization-group calculations that lead to the appropriate linear and nonlinear scaling fields for these problems are discussed in detail. The corresponding homogeneity relations for the total noise are valid near the unstable percolation fixed point whatever the relative size of the microscopic noises. The exponents of the superconductor-conductor mixture appear naturally in the scaling form of the noise coming from the imperfect insulators. Analogously, the exponents of the conductor-insulator mixture enter in the scaling form of the noise coming from the imperfect superconductors in the superconductor-conductor problem. Monte Carlo simulations in two and three dimensions confirm that the scaling predictions are valid well beyond the domain of applicability of the Migdal-Kadanoff approach. For all multifractal moments and both types of mixtures, there is a single crossover exponent and a single correlation length associated with the ratio of the microscopic conductances.

  4. Mixture Rasch Models with Joint Maximum Likelihood Estimation

    ERIC Educational Resources Information Center

    Willse, John T.

    2011-01-01

    This research provides a demonstration of the utility of mixture Rasch models. Specifically, a model capable of estimating a mixture partial credit model using joint maximum likelihood is presented. Like the partial credit model, the mixture partial credit model has the beneficial feature of being appropriate for analysis of assessment data…

  5. ThermoData Engine Database - Pure Compounds and Binary Mixtures

    National Institute of Standards and Technology Data Gateway

    SRD 103b NIST ThermoData Engine Version 6.0 - Pure CompoThermoData Engine Database - Pure Compounds and Binary Mixtures (PC database for purchase)   This database contains property data for more than 21,000 pure compounds, 37,500 binary mixtures, 10,000 ternary mixtures, and 6,000 chemical reactions.

  6. 21 CFR 1310.13 - Exemption of chemical mixtures; application.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... any change in the quantitative or qualitative composition of a chemical mixture that has been granted... 21 Food and Drugs 9 2013-04-01 2013-04-01 false Exemption of chemical mixtures; application. 1310... REPORTS OF LISTED CHEMICALS AND CERTAIN MACHINES § 1310.13 Exemption of chemical mixtures; application....

  7. 21 CFR 1310.13 - Exemption of chemical mixtures; application.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... any change in the quantitative or qualitative composition of a chemical mixture that has been granted... 21 Food and Drugs 9 2014-04-01 2014-04-01 false Exemption of chemical mixtures; application. 1310... REPORTS OF LISTED CHEMICALS AND CERTAIN MACHINES § 1310.13 Exemption of chemical mixtures; application....

  8. 21 CFR 1310.13 - Exemption of chemical mixtures; application.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Exemption of chemical mixtures; application. 1310... REPORTS OF LISTED CHEMICALS AND CERTAIN MACHINES § 1310.13 Exemption of chemical mixtures; application. (a... application of all or any part of the Act a chemical mixture consisting of two or more chemical components,...

  9. 21 CFR 1310.13 - Exemption of chemical mixtures; application.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... any change in the quantitative or qualitative composition of a chemical mixture that has been granted... 21 Food and Drugs 9 2012-04-01 2012-04-01 false Exemption of chemical mixtures; application. 1310... REPORTS OF LISTED CHEMICALS AND CERTAIN MACHINES § 1310.13 Exemption of chemical mixtures; application....

  10. Toward the Rational Use of Exposure Information in Mixtures Toxicology

    EPA Science Inventory

    Of all the disciplines of toxicology, perhaps none is as dependent on exposure information as Mixtures Toxicology. Identifying real world mixtures and replicating them in the laboratory (or in silico) is critical to understanding their risks. Complex mixtures such as cigarett...

  11. 40 CFR 721.10676 - Aromatic hydrocarbon mixture (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Aromatic hydrocarbon mixture (generic... Specific Chemical Substances § 721.10676 Aromatic hydrocarbon mixture (generic). (a) Chemical substance and... hydrocarbon mixture (PMN P-12-551) is subject to reporting under this section for the significant new...

  12. 40 CFR 721.5769 - Mixture of nitrated alkylated phenols.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Mixture of nitrated alkylated phenols... Substances § 721.5769 Mixture of nitrated alkylated phenols. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as a mixture of nitrated alkylated...

  13. 40 CFR 721.5769 - Mixture of nitrated alkylated phenols.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Mixture of nitrated alkylated phenols... Substances § 721.5769 Mixture of nitrated alkylated phenols. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as a mixture of nitrated alkylated...

  14. 40 CFR 721.5769 - Mixture of nitrated alkylated phenols.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Mixture of nitrated alkylated phenols... Substances § 721.5769 Mixture of nitrated alkylated phenols. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as a mixture of nitrated alkylated...

  15. 40 CFR 721.5769 - Mixture of nitrated alkylated phenols.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Mixture of nitrated alkylated phenols... Substances § 721.5769 Mixture of nitrated alkylated phenols. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as a mixture of nitrated alkylated...

  16. 40 CFR 721.5769 - Mixture of nitrated alkylated phenols.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

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

  17. 21 CFR 1310.12 - Exempt chemical mixtures.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 9 2014-04-01 2014-04-01 false Exempt chemical mixtures. 1310.12 Section 1310.12 Food and Drugs DRUG ENFORCEMENT ADMINISTRATION, DEPARTMENT OF JUSTICE RECORDS AND REPORTS OF LISTED CHEMICALS AND CERTAIN MACHINES § 1310.12 Exempt chemical mixtures. (a) The chemical mixtures meeting the criteria in paragraphs (c) or (d) of...

  18. Reconstructing genome mixtures from partial adjacencies.

    PubMed

    Mahmoody, Ahmad; Kahn, Crystal L; Raphael, Benjamin J

    2012-01-01

    Many cancer genome sequencing efforts are underway with the goal of identifying the somatic mutations that drive cancer progression. A major difficulty in these studies is that tumors are typically heterogeneous, with individual cells in a tumor having different complements of somatic mutations. However, nearly all DNA sequencing technologies sequence DNA from multiple cells, thus resulting in measurement of mutations from a mixture of genomes. Genome rearrangements are a major class of somatic mutations in many tumors, and the novel adjacencies (i.e. breakpoints) resulting from these rearrangements are readily detected from DNA sequencing reads. However, the assignment of each rearrangement, or adjacency, to an individual cancer genome in the mixture is not known. Moreover, the quantity of DNA sequence reads may be insufficient to measure all rearrangements in all genomes in the tumor. Motivated by this application, we formulate the k-minimum completion problem (k-MCP). In this problem, we aim to reconstruct k genomes derived from a single reference genome, given partial information about the adjacencies present in the mixture of these genomes. We show that the 1-MCP is solvable in linear time in the cases where: (i) the measured, incomplete genome has a single circular or linear chromosome; (ii) there are no restrictions on the chromosomal content of the measured, incomplete genome. We also show that the k-MCP problem, for k ≥ 3 in general, and the 2-MCP problem with the double-cut-and-join (DCJ) distance are NP-complete, when there are no restriction on the chromosomal structure of the measured, incomplete genome. These results lay the foundation for future algorithmic studies of the k-MCP and the application of these algorithms to real cancer sequencing data. PMID:23282028

  19. Flory Theorem for Structurally Asymmetric Mixtures

    NASA Astrophysics Data System (ADS)

    Dobrynin, Andrey; Sun, Frank; Shirvanyants, David; Rubinstein, Gregory; Rubinstein, Michael; Sheiko, Sergei; Lee, Hyung-Il; Matyjaszewski, Krzysztof

    2008-03-01

    The generalization of the Flory theorem for structurally asymmetric mixtures was derived and tested by direct visualization of conformational transformations of brushlike macromolecules embedded in a melt of linear chains. Swelling of a brush molecule was shown to be controlled not only by the degree of polymerization of the surrounding linear chains, NB, but also by the degree of polymerization of the brush's side chains, N, which determines the structural asymmetry of the mixed species. The boundaries of the swelling region were established by scaling analysis as N^2

  20. Flory Theorem for Structurally Asymmetric Mixtures

    NASA Astrophysics Data System (ADS)

    Sun, Frank C.; Dobrynin, Andrey V.; Shirvanyants, David; Lee, Hyung-Il; Matyjaszewski, Krzysztof; Rubinstein, Gregory J.; Rubinstein, Michael; Sheiko, Sergei S.

    2007-09-01

    The generalization of the Flory theorem for structurally asymmetric mixtures was derived and tested by direct visualization of conformational transformations of brushlike macromolecules embedded in a melt of linear chains. Swelling of a brush molecule was shown to be controlled not only by the degree of polymerization (DP) of the surrounding linear chains, NB, but also by the DP of the brush’s side chains, N, which determines the structural asymmetry of the mixed species. The boundaries of the swelling region were established by scaling analysis as N2

  1. HDT mixtures treatment strategies by gas chromatography

    SciTech Connect

    Laquerbe, C.; Contreras, S.; Demoment, J.

    2008-07-15

    Gas phase chromatographic processes are of interest for the separation of hydrogen isotopes from an HDT mixture. For a certain quantity, they are very competitive and present several benefits. Nevertheless no active packing material allows to have simultaneously good enrichment performances for tritium production and high decontamination capabilities for HD gases. The influence of the packing material is first described in this article. Then two specific processes (TCAP and Reverse Chromatography), each well adapted to perform one target, are presented. Finally, the problematic to propose an optimized treatment scheme associating these two processes is formulated. (authors)

  2. Hydrodynamic modes of partially condensed Bose mixtures

    NASA Astrophysics Data System (ADS)

    Armaitis, J.; Stoof, H. T. C.; Duine, R. A.

    2015-04-01

    We generalize the Landau-Khalatnikov hydrodynamic theory for superfluid helium to two-component (binary) Bose mixtures at arbitrary temperatures. In particular, we include the spin-drag terms that correspond to viscous coupling between the clouds. Therefore, our theory not only describes the usual collective modes of the individual components, e.g., first and second sound, but also results in new collective modes, where both constituents participate. We study these modes in detail and present their dispersions using thermodynamic quantities obtained within the Popov approximation.

  3. Gaussian Mixture Model of Heart Rate Variability

    PubMed Central

    Costa, Tommaso; Boccignone, Giuseppe; Ferraro, Mario

    2012-01-01

    Heart rate variability (HRV) is an important measure of sympathetic and parasympathetic functions of the autonomic nervous system and a key indicator of cardiovascular condition. This paper proposes a novel method to investigate HRV, namely by modelling it as a linear combination of Gaussians. Results show that three Gaussians are enough to describe the stationary statistics of heart variability and to provide a straightforward interpretation of the HRV power spectrum. Comparisons have been made also with synthetic data generated from different physiologically based models showing the plausibility of the Gaussian mixture parameters. PMID:22666386

  4. Pycnonuclear reaction rates for binary ionic mixtures

    NASA Technical Reports Server (NTRS)

    Ichimaru, S.; Ogata, S.; Van Horn, H. M.

    1992-01-01

    Through a combination of compositional scaling arguments and examinations of Monte Carlo simulation results for the interparticle separations in binary-ionic mixture (BIM) solids, we have derived parameterized expressions for the BIM pycnonuclear rates as generalizations of those in one-component solids obtained previously by Salpeter and Van Horn and by Ogata et al. We have thereby discovered a catalyzing effect of the heavier elements, which enhances the rates of reactions among the lighter elements when the charge ratio exceeds a critical value of approximately 2.3.

  5. Computing Properties Of Chemical Mixtures At Equilibrium

    NASA Technical Reports Server (NTRS)

    Mcbride, B. J.; Gordon, S.

    1995-01-01

    Scientists and engineers need data on chemical equilibrium compositions to calculate theoretical thermodynamic properties of chemical systems. Information essential in design and analysis of such equipment as compressors, turbines, nozzles, engines, shock tubes, heat exchangers, and chemical-processing equipment. CET93 is general program that calculates chemical equilibrium compositions and properties of mixtures for any chemical system for which thermodynamic data are available. Includes thermodynamic data for more than 1,300 gaseous and condensed species and thermal-transport data for 151 gases. Written in FORTRAN 77.

  6. Flocculation settling characteristics of mud: sand mixtures

    NASA Astrophysics Data System (ADS)

    Manning, Andrew J.; Baugh, John V.; Spearman, Jeremy R.; Whitehouse, Richard J. S.

    2010-04-01

    When natural muds become mixed with sandy sediments in estuaries, it has a direct effect on the flocculation process and resultant sediment transport regime. Much research has been completed on the erosion and consolidation of mud/sand mixtures, but very little is known quantitatively about how mixed sediments interact whilst in suspension, particularly in terms of flocculation. This paper presents the settling velocity findings from a recent laboratory study which examined the flocculation dynamics for three different mud/sand mixtures at different concentrations (0.2-5 g.l-1) and turbulent shear stresses (0.06-0.9 Pa) in a mini-annular flume. The low intrusive video-based Laboratory Spectral Flocculation Characteristics instrument was used to determine floc/aggregate properties (e.g., size, settling velocity, density and mass) for each population. Settling data was assessed in terms of macrofloc (>160 μm) and microfloc (<160 μm) settling parameters: Wsmacro and Wsmicro, respectively. For pure muds, the macroflocs are regarded as the most dominant contributors to the total depositional flux. The parameterised settling data indicates that by adding more sand to a mud/sand mixture, the fall velocity of the macrofloc fraction slows and the settling velocity of microflocs quickens. Generally, a mainly sandy suspension comprising 25% mud and 75% sand (25M:75S), will produce resultant Wsmacro which are slower than Wsmicro. The quickest Wsmicro appears to consistently occur at a higher level of turbulent shear stress (τ ˜ 0.6 Pa) than both the macrofloc and microfloc fractions from suspensions of pure natural muds. Flocculation within a more cohesively dominant muddy-sand suspension (i.e., 75M:25S) produced macroflocs which fell at similar speeds (±10%) to pure mud suspensions at both low (200 mg l-1) and intermediate (1 g l-1) concentrations at all shear stress increments. Also, low sand content suspensions produced Wsmacro values that were faster than the Wsmicro

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

    PubMed

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

    2009-09-01

    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 field conditions. Commercial formulates of penconazole (PC), (RS)-1-[2-(2,4-dichlorophenyl)pentyl]-1H-1,2,4-triazole), dimetomorph (DM), (EZ)-4-[3-(4-chlorophenyl)-3-(3,4-dimethoxyphenyl)acryloyl]morpholine), azoxystrobin (AZ), (methyl (E)-2-{2-[6-(2-cyanophenoxy)pyrimidin-4-yloxy]phenyl}-3-methoxyacrylate), iprovalicarb (IP), (isopropyl 2-methyl-1-[(RS)-1-p-tolylethyl]carbamoyl-(S)-propylcarbamate), metalaxyl (MX), (methyl N-(methoxyacetyl)-N-(2,6-xylyl)-DL-alaninate), fludioxonil (FL), (4-(2,2-difluoro-1,3-benzodioxol-4-yl)-1H-pyrrole-3-carbonitrile) and cyprodinil (CY), (4-cyclopropyl-6-methyl-N-phenylpyrimidin-2-amine) were mixed in water and discharged into the bio-mixture following the time schedule of the treatments carried out in the grapevine in real field conditions. At each treatment, contaminated water with fungicides was circulated repeatedly through the bio-mixture to enhance the sorption of fungicides. In fact, it retained them between 98-100% with the exception of MX of which it was able to retain only 90.5%. The adsorption/desorption experiment showed that repeated circulation of water, instead of enhancing MX retention, can easily remove about 30% of MX already adsorbed by the bio-mixture. This finding suggests that water contaminated by very mobile pesticides should be discharged at the end of field treatments without re-circulating the water in order to avoid the release of pesticides weakly adsorbed on the bio-mixture. PMID:20183083

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

    SciTech Connect

    Not Available

    1985-01-01

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

  9. Fluid Latent Heat Storage Material Using Ethanol Water Mixture

    NASA Astrophysics Data System (ADS)

    Ohkubo, Hidetoshi; Yasunari, Yuki

    Ethanol water 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. With advances in low temperature technology in recent days, ethanol water mixture is attaching more and more attention as an environment-friendly coolant or as a thermal storage material. In the present study, we observed the crystallization process in the mixture and carried out experiments to evaluate fluidity of the mixture, with the objective of utilizing an ethanol water mixture as a coolant or a thermal energy storage material. Crystal formation and growing process within a minute droplet of a binary mixture was modeled. As a result, we found a novel method to produce a fluid latent heat storage material continuously and an apparent coefficient of viscosity show that rotational speed and solid phase fraction have a strong effect on the fluidity of the mixture.

  10. Prechamber initiation of detonation in gaseous mixtures

    NASA Astrophysics Data System (ADS)

    Bivol, G. Yu; Golovastov, S. V.; Golub, V. V.

    2015-11-01

    A process of deflagration-to-detonation transition in propane-butane-oxygen and acetylene-oxygen mixtures, in an open channel with a circular cross section with a diameter of 3 mm, was investigated experimentally. Detonation initiation was carried out by burning the mixture in the prechamber connected to the channel. The prechamber was considered as an extended source for the initiation of the detonation of a finite volume. To measure the velocity of a flame front, photodiodes, installed along the axis of the channel, were used. To determine the boundary conditions at the entrance to the channel, a piezoelectric pressure transducer was used. The influence of the dimensions of the prechamber, equivalence ratio and fuel on the pressure profile, and evolution of the flame front along the axis of the channel are presented. It was shown that, the dynamics of the flame front and shock waves in the channel can occur in different scenarios depending on the geometry of the prechamber and equivalence ratio. Two limit effects of the prechamber detonation initiation in the channel have been analyzed. The pre-detonation distances and the minimal energy of direct initiation of the detonation were determined.

  11. Transport and radiation in complex LTE mixtures

    NASA Astrophysics Data System (ADS)

    Janssen, Jesper; Peerenboom, Kim; Suijker, Jos; Gnybida, Mykhailo; van Dijk, Jan

    2014-10-01

    Complex LTE mixtures are for example encountered in re-entry, welding, spraying and lighting. These mixtures typically contain a rich chemistry in combination with large temperature gradients. LTE conditions are also interesting because they can aid in the validation of NLTE algorithms. An example is the calculation of transport properties. In this work a mercury free high intensity discharge lamp is considered. The investigation focusses on using salts like InI or SnI as a buffer species. By using these species a dominant background gas like mercury is no longer present. As a consequence the diffusion algorithms based on Fick's law are no longer applicable and the Stefan-Maxwell equations must be solved. This system of equations is modified with conservation rules to set a coldspot pressure for saturated species and enforce the mass dosage for unsaturated species. The radiative energy transport is taken into account by raytracing. Quantum mechanical simulations have been used to calculate the potential curves and the transition dipole moments for indium with iodine and tin with iodine. The results of these calculations have been used to predict the quasistatic broadening by iodine. The work was supported by the project SCHELP from the Belgium IWT (Project Number 110003) and the CATRENE SEEL Project (CA502).

  12. Putting Priors in Mixture Density Mercer Kernels

    NASA Technical Reports Server (NTRS)

    Srivastava, Ashok N.; Schumann, Johann; Fischer, Bernd

    2004-01-01

    This paper presents a new methodology for automatic knowledge driven data mining based on the theory of Mercer Kernels, which are highly nonlinear symmetric positive definite mappings from the original image space to a very high, possibly infinite dimensional feature space. We describe a new method called Mixture Density Mercer Kernels to learn kernel function directly from data, rather than using predefined kernels. These data adaptive kernels can en- code prior knowledge in the kernel using a Bayesian formulation, thus allowing for physical information to be encoded in the model. We compare the results with existing algorithms on data from the Sloan Digital Sky Survey (SDSS). The code for these experiments has been generated with the AUTOBAYES tool, which automatically generates efficient and documented C/C++ code from abstract statistical model specifications. The core of the system is a schema library which contains template for learning and knowledge discovery algorithms like different versions of EM, or numeric optimization methods like conjugate gradient methods. The template instantiation is supported by symbolic- algebraic computations, which allows AUTOBAYES to find closed-form solutions and, where possible, to integrate them into the code. The results show that the Mixture Density Mercer-Kernel described here outperforms tree-based classification in distinguishing high-redshift galaxies from low- redshift galaxies by approximately 16% on test data, bagged trees by approximately 7%, and bagged trees built on a much larger sample of data by approximately 2%.

  13. Mutual diffusion in a binary isotopic mixture.

    PubMed

    Sharma, Raman; Tankeshwar, K

    2010-11-17

    The mass dependence of the mutual diffusion coefficient, in a binary equimolar mixture of Lennard-Jones fluids, is studied within Mori's memory function formalism. A phenomenological form of the memory function is used to study the time evolution of the self- and relative velocity correlation functions. The diffusion coefficients are calculated from the relevant velocity correlation functions using the Green-Kubo integral formula. Like the self-diffusion coefficient, the mutual diffusion coefficient is also found to be weakly dependent on the mass ratio. The present study shows that the minimum value that the mutual diffusion coefficient in an equimolar mixture of isotopic fluids can have is √(1/2) times the self-diffusion coefficient of any of the species when in isolation. Further, the contribution of the dynamic/distinct cross correlations to the mutual diffusion coefficient is found to be small and positive for the whole range of the mass ratio which is consistent with earlier molecular dynamics results. PMID:21339621

  14. Predicting the toxicity of metal mixtures.

    PubMed

    Balistrieri, Laurie S; Mebane, Christopher A

    2014-01-01

    The toxicity of single and multiple metal (Cd, Cu, Pb, and Zn) solutions to trout is predicted using an approach that combines calculations of: (1) solution speciation; (2) competition and accumulation of cations (H, Ca, Mg, Na, Cd, Cu, Pb, and Zn) on low abundance, high affinity and high abundance, low affinity biotic ligand sites; (3) a toxicity function that accounts for accumulation and potency of individual toxicants; and (4) biological response. The approach is evaluated by examining water composition from single metal toxicity tests of trout at 50% mortality, results of theoretical calculations of metal accumulation on fish gills and associated mortality for single, binary, ternary, and quaternary metal solutions, and predictions for a field site impacted by acid rock drainage. These evaluations indicate that toxicity of metal mixtures depends on the relative affinity and potency of toxicants for a given aquatic organism, suites of metals in the mixture, dissolved metal concentrations and ratios, and background solution composition (temperature, pH, and concentrations of major ions and dissolved organic carbon). A composite function that incorporates solution composition, affinity and competition of cations for two types of biotic ligand sites, and potencies of hydrogen and individual metals is proposed as a tool to evaluate potential toxicity of environmental solutions to trout. PMID:23973545

  15. Variational Inference for Watson Mixture Model.

    PubMed

    Taghia, Jalil; Leijon, Arne

    2016-09-01

    This paper addresses modelling data using the Watson distribution. The Watson distribution is one of the simplest distributions for analyzing axially symmetric data. This distribution has gained some attention in recent years due to its modeling capability. However, its Bayesian inference is fairly understudied due to difficulty in handling the normalization factor. Recent development of Markov chain Monte Carlo (MCMC) sampling methods can be applied for this purpose. However, these methods can be prohibitively slow for practical applications. A deterministic alternative is provided by variational methods that convert inference problems into optimization problems. In this paper, we present a variational inference for Watson mixture models. First, the variational framework is used to side-step the intractability arising from the coupling of latent states and parameters. Second, the variational free energy is further lower bounded in order to avoid intractable moment computation. The proposed approach provides a lower bound on the log marginal likelihood and retains distributional information over all parameters. Moreover, we show that it can regulate its own complexity by pruning unnecessary mixture components while avoiding over-fitting. We discuss potential applications of the modeling with Watson distributions in the problem of blind source separation, and clustering gene expression data sets. PMID:26571512

  16. Mixture Model For Overdispersion of Precipitation.

    NASA Astrophysics Data System (ADS)

    Katz, Richardw.; Zheng, Xiaogu

    1999-08-01

    Stochastic models fit to time series of daily precipitation amount generally ignore any year-to-year (i.e., low frequency) source of random variation, and such models are known to underestimate the interannual variance of monthly or seasonal total precipitation. To explicitly account for this `overdispersion' phenomenon, a mixture model is proposed. A hidden index, taking on one of two possible states, is assumed to exist (perhaps representing different modes of atmospheric circulation). To represent the intermittency of precipitation and the tendency of wet or dry spells to persist, a stochastic model known as a chain-dependent process is applied. The parameters of this stochastic model are permitted to vary conditionally on the hidden index.Data for one location in California (whose previous study motivated the present approach), as well as for another location in New Zealand, are analyzed. To estimate the parameters of a mixture of two conditional chain-dependent processes by maximum likelihood, the `expectation-maximization algorithm' is employed. It is demonstrated that this approach can either eliminate or greatly reduce the extent of the overdispersion phenomenon. Moreover, an attempt is made to relate the hidden indexes to observed features of atmospheric circulation. This approach to dealing with overdispersion is contrasted with the more prevalent alternative of fitting more complex stochastic models for high-frequency variations to time series of daily precipitation.

  17. Detonation and deflagration properties of pyrotechnic mixtures

    SciTech Connect

    Tanaka, Katsumi

    1996-07-01

    Theoretical calculation of detonation and deflagration properties of pyrotechnic mixtures have been performed including report charges and display charges. Calculation were performed with the KHT (Kihara-Hikta-Tanaka) code. KHT results are compared with a modified version of the TIGER code which allows calculation with 900 gaseous and 600 condensed product species at high pressure. Detonation properties computed by KHT and BKWS (Becker-Kistiakowskii-Wilson) give favorable agreement with experimental results of detonation velocity measurements. Hydrodynamic computation by one dimensional Lagrangian hydrodynamic code using the isentrope given by KHT constant volume explosion, indicated that experimental results for blast wave measurement for 30kg and 50kg of report charge were an incomplete reaction. Underwater detonation experiments with explosive charge of 25g, however, indicates a more energetic nature than the KHT prediction. This scale effect indicates complicated slow reactions and a number of condensed phase deflagration products of powder mixtures such as aluminum or titanium with oxidizers such as potassium perchlorate or nitrate salts as suggested by Hobbs et al.

  18. Liquid crystal-carbon nanotubes mixtures

    NASA Astrophysics Data System (ADS)

    Popa-Nita, V.; Kralj, S.

    2010-01-01

    The self-organizing properties of nematic liquid crystals (LCs) can be used to align carbon nanotubes (CNTs) dispersed in them. In the previous paper [P. van der Schoot, V. Popa-Nita, and S. Kralj, J. Phys. Chem. B 112, 4512 (2008)], we have considered the weak anchoring limit of the nematic LC molecules at the nanotube's surface, where the CNT alignment is caused by the anisotropic interfacial tension of the nanotubes in the nematic host fluid. In this paper, we present the theoretical results obtained for strong enough anchoring at the CNT-LC interface for which the nematic ordering around nanotube is apparently distorted. Consequently, relatively strong long-range and anisotropic interactions can emerge within the system. In order to get insight into the impact of LC ordering on the alignment of nanotubes we treat the two mixture components on the same footing and combine Landau-de Gennes free energy for the thermotropic ordering of the liquid crystal and Doi free energy for lyotropic nematic ordering of carbon nanotubes caused by their mutually excluded volume. The phase ordering of the binary mixture is analyzed as a function of the volume fraction of the carbon nanotubes, the strength of coupling, and the temperature. We find that the degree of ordering of the nanorods can be tuned by raising or lowering the temperature or by increasing or decreasing their concentration.

  19. Optical Properties of Thin Film Molecular Mixtures

    NASA Technical Reports Server (NTRS)

    Jaworske, Donald A.; Shumway, Dean A.; Lyons, Valerie (Technical Monitor)

    2002-01-01

    Thin films composed of molecular mixtures of metal and dielectric are being considered for use as solar selective coatings for a variety of space power applications. By controlling the degree of molecular mixing, the solar selective coatings can be tailored to have the combined properties of high solar absorptance, alpha, and low infrared emittance, epsilon. On orbit, these combined properties would simultaneously maximize the amount of solar energy captured by the coating and minimize the amount of thermal energy radiated. Mini-satellites equipped with solar collectors coated with these cermet coatings may utilize the captured heat energy to power a heat engine to generate electricity, or to power a thermal bus that directs heat to remote regions of the spacecraft. Early work in this area identified the theoretical boundary conditions needed to operate a Carnot cycle in space, including the need for a solar concentrator, a solar selective coating at the heat inlet of the engine, and a radiator. A solar concentrator that can concentrate sunlight by a factor of 100 is ideal. At lower values, the temperature of the solar absorbing surface becomes too low for efficient heat engine operation, and at higher values, cavity type heat receivers become attractive. In designing the solar selective coating, the wavelength region yielding high solar absorptance must be separated from the wavelength region yielding low infrared emittance by establishing a sharp transition in optical properties. In particular, a sharp transition in reflectance is desired in the infrared to achieve the desired optical performance. For a heat engine operating at 450C, a sharp transition at 1.8 micrometers is desired. The radiator completes the heat flow through the Carnot cycle. Additional work has been done supporting the use of molecular mixtures for terrestrial applications. Sputter deposition provides a means to apply coatings to the tubes that carry a working fluid at the focus of trough

  20. A numerical study of laminar flames propagating in stratified mixtures

    NASA Astrophysics Data System (ADS)

    Zhang, Jiacheng

    Numerical simulations are carried out to study the structure and speed of laminar flames propagating in compositionally and thermally stratified fuel-air mixtures. The study is motivated by the need to understand the physics of flame propagation in stratified-charge engines and model it. The specific question of interest in this work is: how does the structure and speed of the flame in the stratified mixture differ from that of the flame in a corresponding homogeneous mixture at the same equivalence ratio, temperature, and pressure? The studies are carried out in hydrogen-air, methane-air, and n-heptane-air mixtures. A 30-species 184-step skeletal mechanism is employed for methane oxidation, a 9-species 21-step mechanism for hydrogen oxidation, and a 37-species 56-step skeletal mechanism for n-heptane oxidation. Flame speed and structure are compared with corresponding values for homogeneous mixtures. For compositionally stratified mixtures, as shown in prior experimental work, the numerical results suggest that when the flame propagates from a richer mixture to a leaner mixture, the flame speed is faster than the corresponding speed in the homogeneous mixture. This is caused by enhanced diffusion of heat and species from the richer mixture to the leaner mixture. In fact, the effects become more pronounced in leaner mixtures. Not surprisingly, the stratification gradient influences the results with shallower gradients showing less effect. The controlling role that diffusion plays is further assessed and confirmed by studying the effect of a unity Lewis number assumption in the hydrogen/air mixtures. Furthermore, the effect of stratification becomes less important when using methane or n-heptane as fuel. The laminar flame speed in a thermally stratified mixture is similar to the laminar flame speed in homogeneous mixture at corresponding unburned temperature. Theoretical analysis is performed and the ratio of extra thermal diffusion rate to flame heat release rate

  1. Catalyst mixture for the catalytic reduction of nitrogen oxides in gaseous mixtures

    SciTech Connect

    Ginger, E.

    1981-03-24

    A physical mixture of a first and second catalyst is described. The first catalyst comprises copper or a copper compound, preferably copper sulfate supported on a porous carrier material. The second catalyst is a combination of metals or compounds thereof, preferably sulfates of vanadium and iron or tungsten and iron, also dispersed on a porous carrier material.

  2. Combined photobacterium toxicity of herbicide mixtures containing one insecticide.

    PubMed

    Liu, Shu-Shen; Song, Xiao-Qing; Liu, Hai-Ling; Zhang, Ya-Hui; Zhang, Jing

    2009-04-01

    To test whether the dose-addition (DA) model can predict the combined toxicity of the mixtures of herbicides that coexisted with insecticide(s), we selected five herbicides (simetryn, prometon, bromacil, velpar, and diquat) and one organophosphorus insecticide (dichlorvos) as the test components. The inhibition toxicities of the six pesticides as well as those of their mixtures to Vibrio qinghaiensis sp.-Q67 were determined by using the microplate toxicity test procedure. The dose-response curves (DRCs) between the observed inhibition toxicities and the doses of the pesticides or the mixtures were modeled by using the nonlinear least square fitting. It was shown that all dose-response relationships were effectively described by the Weibull function. To fully explore the combined toxicities of mixtures including various concentration compositions, we designed three equivalent-effect concentration ratio (EECR) mixtures and six uniform design concentration ratio (UDCR) mixtures. The combined toxicity of a mixture is identified by inspecting whether the DRC predicted by the dose addition (DA) or independent action (IA) locates in the 95% confidence interval of the DRC of the mixture. Furthermore, the possible reason for the three mixtures to depart from the DA action was the very high concentration ratio of diquat in the mixtures. PMID:19215957

  3. Processing of odor mixtures in the zebrafish olfactory bulb.

    PubMed

    Tabor, Rico; Yaksi, Emre; Weislogel, Jan-Marek; Friedrich, Rainer W

    2004-07-21

    Components of odor mixtures often are not perceived individually, suggesting that neural representations of mixtures are not simple combinations of the representations of the components. We studied odor responses to binary mixtures of amino acids and food extracts at different processing stages in the olfactory bulb (OB) of zebrafish. Odor-evoked input to the OB was measured by imaging Ca2+ signals in afferents to olfactory glomeruli. Activity patterns evoked by mixtures were predictable within narrow limits from the component patterns, indicating that mixture interactions in the peripheral olfactory system are weak. OB output neurons, the mitral cells (MCs), were recorded extra- and intracellularly and responded to odors with stimulus-dependent temporal firing rate modulations. Responses to mixtures of amino acids often were dominated by one of the component responses. Responses to mixtures of food extracts, in contrast, were more distinct from both component responses. These results show that mixture interactions can result from processing in the OB. Moreover, our data indicate that mixture interactions in the OB become more pronounced with increasing overlap of input activity patterns evoked by the components. Emerging from these results are rules of mixture interactions that may explain behavioral data and provide a basis for understanding the processing of natural odor stimuli in the OB. PMID:15269273

  4. Modified mixture of experts for diabetes diagnosis.

    PubMed

    Ubeyli, Elif Derya

    2009-08-01

    Diagnosis tasks are among the most interesting activities in which to implement intelligent systems. The major objective of the paper is to be a guide for the readers, who want to develop an automated decision support system for detection of diabetics and subjects having risk factors of diabetes. The purpose was to determine an optimum classification scheme with high diagnostic accuracy for this problem. Several different classification algorithms were tested and their performances in detection of diabetics were compared. The performance of the classification algorithms was illustrated on the Pima Indians diabetes data set. The present research demonstrated that the modified mixture of experts (MME) achieved diagnostic accuracies which were higher than that of the other automated diagnostic systems. PMID:19697696

  5. Coarsening in binary solid-liquid mixtures

    NASA Technical Reports Server (NTRS)

    Voorhees, P. W.

    1990-01-01

    A theory of Ostwald ripening has been developed for a solid-liquid mixture cosisting of a low volume fraction array of spherical solid particles in a liquid wherein the coarsening process proceeds via the transport of both heat and mass. It is found that the simultaneous transport of heat and mass during ripening does not alter the exponents of the temporal power laws governing the ripening process from their classical values but does alter the amplitudes of these power laws. The growth rate of the cube of the average particle radius, the rate constant, is found to depend both on the alloy solute concentration and the ratio of the thermal to solutal diffusivities. In most metallic systems, a large decrease in the rate constant can be expected with small additions of solute to a pure metal. Possible extensions of this theory to the analogous problem of ripening in isothermal ternary alloys are also discussed.

  6. CRITICALITY CURVES FOR PLUTONIUM HYDRAULIC FLUID MIXTURES

    SciTech Connect

    WITTEKIND WD

    2007-10-03

    This Calculation Note performs and documents MCNP criticality calculations for plutonium (100% {sup 239}Pu) hydraulic fluid mixtures. Spherical geometry was used for these generalized criticality safety calculations and three geometries of neutron reflection are: {sm_bullet}bare, {sm_bullet}1 inch of hydraulic fluid, or {sm_bullet}12 inches of hydraulic fluid. This document shows the critical volume and critical mass for various concentrations of plutonium in hydraulic fluid. Between 1 and 2 gallons of hydraulic fluid were discovered in the bottom of HA-23S. This HA-23S hydraulic fluid was reported by engineering to be Fyrquel 220. The hydraulic fluid in GLovebox HA-23S is Fyrquel 220 which contains phosphorus. Critical spherical geometry in air is calculated with 0 in., 1 in., or 12 inches hydraulic fluid reflection.

  7. A Fast Incremental Gaussian Mixture Model

    PubMed Central

    Pinto, Rafael Coimbra; Engel, Paulo Martins

    2015-01-01

    This work builds upon previous efforts in online incremental learning, namely the Incremental Gaussian Mixture Network (IGMN). The IGMN is capable of learning from data streams in a single-pass by improving its model after analyzing each data point and discarding it thereafter. Nevertheless, it suffers from the scalability point-of-view, due to its asymptotic time complexity of O(NKD3) for N data points, K Gaussian components and D dimensions, rendering it inadequate for high-dimensional data. In this work, we manage to reduce this complexity to O(NKD2) by deriving formulas for working directly with precision matrices instead of covariance matrices. The final result is a much faster and scalable algorithm which can be applied to high dimensional tasks. This is confirmed by applying the modified algorithm to high-dimensional classification datasets. PMID:26444880

  8. Study of superfluid Bose-Fermi mixture

    NASA Astrophysics Data System (ADS)

    Laurent, Sebastien; Delehaye, Marion; Jin, Shuwei; Pierce, Matthieu; Yefsah, Tarik; Chevy, Frederic; Salomon, Christophe

    2016-05-01

    Using fermionic and bosonic isotopes of lithium we produce and study ultracold Bose-Fermi mixtures. First in a low temperature counterflow experiment, we measure the critical velocity of the system in the BEC-BCS crossover. Around unitarity, we observe a remarkably high superfluid critical velocity which reaches the sound velocity of the strongly interacting Fermi gas. Second, when we increase the temperature of the system slightly above the superfluid transitions we observe an unexpected phase locking of the oscillations of the clouds induced by dissipation. Finally, as suggested in, we explore the nature of the superfluid phase when we impose a spin polarization in the situation where the mean field potential created by the bosons on the fermions tends to cancel out the trapping potential of the latter.

  9. Autoignition of adiabatically compressed combustible gas mixtures

    SciTech Connect

    Hu, H.; Keck, J.

    1987-01-01

    Measurements of explosion limits for fuel/air/diluent mixtures compressed by an expanding laminar flame have been made in a constant volume spherical bomb. The fuels studied to date range from butane to octane at fuel/air equivalence ratios from 0.8 to 1.3. The explosion pressures and temperatures range from 10 to 100 atm and 650 to 850 K. The pressure versus time curves show the behavior typical of the two-stage ignition process observed in rapid compression machines. A branched chain kinetic model has been developed to correlate the data. The model has been used to predict both the explosion limits measured in the current bomb experiments and ignition delays measured in prior rapid compression machine experiments. Good agreement between experiment and theory can be achieved with minor adjustment in published rate constants.

  10. Urea and deuterium mixtures at high pressures

    SciTech Connect

    Donnelly, M. Husband, R. J.; Frantzana, A. D.; Loveday, J. S.; Bull, C. L.; Klotz, S.

    2015-03-28

    Urea, like many network forming compounds, has long been known to form inclusion (guest-host) compounds. Unlike other network formers like water, urea is not known to form such inclusion compounds with simple molecules like hydrogen. Such compounds if they existed would be of interest both for the fundamental insight they provide into molecular bonding and as potential gas storage systems. Urea has been proposed as a potential hydrogen storage material [T. A. Strobel et al., Chem. Phys. Lett. 478, 97 (2009)]. Here, we report the results of high-pressure neutron diffraction studies of urea and D{sub 2} mixtures that indicate no inclusion compound forms up to 3.7 GPa.