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1

Separation of organic azeotropic mixtures by pervaporation  

SciTech Connect

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.

Baker, R.W.

1991-12-01

2

Separation of organic azeotropic mixtures by pervaporation. Final technical report  

SciTech Connect

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.

Baker, R.W.

1991-12-01

3

Separation of Azeotropic Mixtures in Closed Batch Distillation Arrangements  

E-print Network

Separation of Azeotropic Mixtures in Closed Batch Distillation Arrangements S. Skouras and S, Norway SCOPE OF THE PROJECT ·How can we separate ternary mixtures in closed batch distillation-up period is required, followed by a heteroazeotropic distillation step (Figure 3) Modified: The separation

Skogestad, Sigurd

4

Analysis of Closed Multivessel Batch Distillation of Ternary Azeotropic Mixtures  

E-print Network

Analysis of Closed Multivessel Batch Distillation of Ternary Azeotropic Mixtures using Elementary) diagrams like distillation lines and isotherms maps may be used in analysis of the closed (total reflux) multivessel batch distillation column. An indirect level control strategy is implemented that eliminates

Skogestad, Sigurd

5

Anthracene + Pyrene Solid Mixtures: Eutectic and Azeotropic Character  

PubMed Central

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

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

2010-01-01

6

Performance evaluation of two azeotropic refrigerant mixtures of HFC134a with R-290 (propane) and R-600a (isobutane)  

Microsoft Academic Search

The reduction in chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC) production and the scheduled phase-out of these ozone-depleting refrigerants require the development and determination of environmentally safe refrigerants for use in heat pumps, water chillers, air conditioners, and refrigerators. This paper presents a performance evaluation of a generic heat pump with two azeotropic refrigerant mixtures of HFC-134a (1,1,1,2-tetrachloroethane) with R-290 (propane) and

M. S. Kim; W. J. Mulroy; D. A. Didion

1994-01-01

7

Performance evaluation of two azeotropic refrigerant mixtures of HFC-134a with R-290 (propane) and R-600a (isobutane)  

SciTech Connect

The reduction in chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC) production and the scheduled phase-out of these ozone-depleting refrigerants require the development and determination of environmentally safe refrigerants for use in heat pumps, water chillers, air conditioners, and refrigerators. This paper presents a performance evaluation of a generic heat pump with two azeotropic refrigerant mixtures of HFC-134a (1,1,1,2-tetrachloroethane) with R-290 (propane) and R-600a (isobutane); R-290/134a (45/55 by mass percentage) and R-134a/600a (80/20 by mass percentage). The performance characteristics of the azeotropes were compared with pure CFC-12, HFC-134a, HCFC-22, and R-290 at the high temperature cooling and heating conditions including those using liquid-line/suction-line heat exchange. The coefficient of performance of R-290/134a is lower than that of HCFC-22 and R-290, and R-134a/600a shows higher coefficient of performance than CFC-12 and HFC-134a. The capacity for R-290/134a is higher than that for HCFC-22 and R-290, and R-134a/600a exhibits higher system capacity than CFC-12 and HFC-134a. Experimental results show that the discharge temperatures of the studied azeotropic mixtures are lower than those of the pure refrigerants, CFC-12 and HCFC-22.

Kim, M.S.; Mulroy, W.J.; Didion, D.A. (National Inst. of Standards and Technology, Gaithersburg, MD (United States). Building and Fire Research Lab.)

1994-06-01

8

SIMULATION OF NON-AZEOTROPIC REFRIGERANT MIXTURES FOR USE IN A DUAL-CIRCUIT REFRIGERATOR/FREEZER WITH COUNTERCURRENT HEAT EXCHANGES  

EPA Science Inventory

The paper discusses a refrigerator/freezer (RF) system that has two complete and independent refrigeration cycles for the two compartments. It uses a non-azeotropic refrigerant mixture (NARM) in each cycle and countercurrent heat exchangers throughout. This RF is housed in a stan...

9

Recovery of organic carbon from atmospheric particulate matter using soxhlet extraction with the benzene/methanol azeotrope  

SciTech Connect

The extraction efficiency of the benzene/methanol azeotrope for organic carbon in atmospheric particulate matter was determined using a carbon types analyzer and also radio-labeled tracers and liquid scintillation spectroscopy. A twenty-four hour Soxhlet extraction with the azeotrope extracts 76 percent of the organic carbon, 15 percent of the elemental carbon, and 61 percent of the total carbon. Nonpolar and moderately polar organic compounds such as dotriacontane, benzo(a)pyrene, and stearic acid are extracted with 95 percent recovery. Highly polar oxygenated species such as succinic acid are extracted with an efficiency of 82 percent. The Soxhlet extractor was more efficient than ultrasonication for the extraction of highly polar species.

Barkenbus, B.D.; Griest, W.H.; Huntzicker, J.J.; Heyerdahl, E.K.; MacDougall, C.S.

1983-01-01

10

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

NASA Astrophysics Data System (ADS)

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

Liu, Xin

1996-11-01

11

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

PubMed

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

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

2015-04-01

12

Supercritical separation process for complex organic mixtures  

DOEpatents

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.

Chum, Helena L. (Arvada, CO); Filardo, Giuseppe (Palermo, IT)

1990-01-01

13

Azeotropic Distillation as a Technique for Emulsion Size Reduction  

E-print Network

Azeotropic Distillation as a Technique for Emulsion Size Reduction Taylor Emanuelle Sweet 2013 Prism/PCCM #12;Overview -Intro- What is Microfluidics? What is Heterogeneous Azeotropic Distillation microns in size and use Binary Heterogeneous Azeotropic Distillation to shrink droplets to 5-10 microns

Petta, Jason

14

Secondary organic aerosol from biogenic volatile organic compound mixtures  

NASA Astrophysics Data System (ADS)

The secondary organic aerosol (SOA) yields from the ozonolysis of a Siberian fir needle oil (SFNO), a Canadian fir needle oil (CFNO), and several SOA precursor mixtures containing reactive and non-reactive volatile organic compounds (VOCs) were investigated. The use of precursor mixtures more completely describes the atmosphere where many VOCs exist. The addition of non-reactive VOCs such as bornyl acetate, camphene, and borneol had very little to no effect on SOA yields. The oxidation of VOC mixtures with VOC mass percentages similar to the SFNO produced SOA yields that became more similar to the SOA yield from SFNO as the complexity and concentration of VOCs within the mixture became more similar to overall SFNO composition. The SOA yield produced by the oxidation of CFNO was within the error of the SOA yield produced by the oxidation of SFNO at a similar VOC concentration. The SOA yields from SFNO were modeled using the volatility basis set (VBS), which predicts the SOA yields for a given mass concentration of mixtures containing similar VOCs.

Hatfield, Meagan L.; Huff Hartz, Kara E.

2011-04-01

15

Azeotropy in the natural and synthetic refrigerant mixtures  

Microsoft Academic Search

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

Sergey Artemenko; Victor Mazur

2007-01-01

16

Calculation of a double reactive azeotrope using stochastic optimization approaches  

NASA Astrophysics Data System (ADS)

An homogeneous reactive azeotrope is a thermodynamic coexistence condition of two phases under chemical and phase equilibrium, where compositions of both phases (in the Ung-Doherty sense) are equal. This kind of nonlinear phenomenon arises from real world situations and has applications in chemical and petrochemical industries. The modeling of reactive azeotrope calculation is represented by a nonlinear algebraic system with phase equilibrium, chemical equilibrium and azeotropy equations. This nonlinear system can exhibit more than one solution, corresponding to a double reactive azeotrope. The robust calculation of reactive azeotropes can be conducted by several approaches, such as interval-Newton/generalized bisection algorithms and hybrid stochastic-deterministic frameworks. In this paper, we investigate the numerical aspects of the calculation of reactive azeotropes using two metaheuristics: the Luus-Jaakola adaptive random search and the Firefly algorithm. Moreover, we present results for a system (with industrial interest) with more than one azeotrope, the system isobutene/methanol/methyl-tert-butyl-ether (MTBE). We present convergence patterns for both algorithms, illustrating - in a bidimensional subdomain - the identification of reactive azeotropes. A strategy for calculation of multiple roots in nonlinear systems is also applied. The results indicate that both algorithms are suitable and robust when applied to reactive azeotrope calculations for this "challenging" nonlinear system.

Mendes Platt, Gustavo; Pinheiro Domingos, Roberto; Oliveira de Andrade, Matheus

2013-02-01

17

EFFECTS IN HUMANS OF A VOLATILE ORGANIC COMPOUND MIXTURE: SENSORY  

EPA Science Inventory

Time-course actions for symptoms of the sick building syndrome were derived from 66 healthy males exposed to clean air and a volatile organic (VOC) mixture in separate sessions. he mixture contained 22 VOCs (25 mg/m3 total concentration) commonly found air-borne in new or recentl...

18

Flammability of gas mixtures containing volatile organic compounds and hydrogen  

Microsoft Academic Search

An experimental program was conducted to evaluate the accuracy of some current methods for predicting the flammability of gas mixtures containing hydrogen and flammable or nonflammable volatile organic compounds (VOCs) in air. The specific VOCs tested were toluene, 1,2-dichloroethane, 2-butanone, and carbon tetrachloride. The lower flammability limits (LFLs) of gas mixtures containing equal molar quantities of the components were determined

Kevin J. Liekhus; Isaac A. Zlochower; Kenneth L. Cashdollar; Sinisa M. Djordjevic; Cindy A. Loehr

2000-01-01

19

PREDICTIONS OF AZEOTROPES FORMED FROM FLUORINATED ETHERS, ETHANES, AND PROPANES  

EPA Science Inventory

The paper discusses an evaluation of the potential for azeotrope formation and performance for fluorinated ethers, ethanes, and propanes. (NOTE: The synthesis of new non-chlorinated refrigerants expands the base of alternatives for replacing ozone-depleting chlorofluorocarbons (O...

20

Lateral organization of complex lipid mixtures from multiscale modeling  

PubMed Central

The organizational properties of complex lipid mixtures can give rise to functionally important structures in cell membranes. In model membranes, ternary lipid-cholesterol (CHOL) mixtures are often used as representative systems to investigate the formation and stabilization of localized structural domains (“rafts”). In this work, we describe a self-consistent mean-field model that builds on molecular dynamics simulations to incorporate multiple lipid components and to investigate the lateral organization of such mixtures. The model predictions reveal regions of bimodal order on ternary plots that are in good agreement with experiment. Specifically, we have applied the model to ternary mixtures composed of dioleoylphosphatidylcholine:18:0 sphingomyelin:CHOL. This work provides insight into the specific intermolecular interactions that drive the formation of localized domains in these mixtures. The model makes use of molecular dynamics simulations to extract interaction parameters and to provide chain configuration order parameter libraries. PMID:20151760

Tumaneng, Paul W.; Pandit, Sagar A.; Zhao, Guijun; Scott, H. L.

2010-01-01

21

Estimation of Interfacial Tension between Organic Liquid Mixtures and Water  

SciTech Connect

Knowledge of IFT values for chemical mixtures helps guide the design and analysis of various processes, including NAPL remediation with surfactants or alcohol flushing, enhanced oil recovery, and chemical separation technologies, yet available literature values are sparse. A comprehensive comparison of thermodynamic and empirical models for estimating interfacial tension (IFT) of organic chemical mixtures with water is conducted, mainly focusing on chlorinated organic compounds for 14 ternary, three quaternary, and one quinary systems. Emphasis is placed on novel results for systems with three and four organic chemical compounds, and for systems with composite organic compounds like lard oil and mineral oil. Seven models are evaluated: the ideal and nonideal monolayer models (MLID and MLNID), the ideal and nonideal mutual solubility models (MSID and MSNID), an empirical model for ternary systems (EM), a linear mixing model based on mole fractions (LMMM), and a newly developed linear mixing model based on volume fractions of organic mixtures (LMMV) for higher order systems. The two ideal models (MLID and MSID) fit ternary systems of chlorinated organic compounds without surface active compounds relatively well. However, both ideal models did not perform well for the mixtures containing a surface active compound. However, for these systems, both the MLNID and MSNID models matched the IFT data well. It is shown that the MLNID model with a surface coverage value (0.00341 mmol/m2) obtained in this study can practically be used for chlorinated organic compounds. The LMMM results in poorer estimates of the IFT as the difference in IFT values of individual organic compounds in a mixture increases. The EM, with two fitting parameters, provided accurate results for all 14 ternary systems including composite organic compounds. The new LMMV method for quaternary and higher component systems was successfully tested. This study shows that the LMMV may be able to be used for higher component systems and it can be easily incorporated into compositional multiphase flow models using only parameters from ternary systems.

Yoon, Hongkyu; Oostrom, Martinus; Werth, Charles J.

2009-10-15

22

A Novel Azeotropic Mixture for Solvent Extraction of Edible Oils  

Microsoft Academic Search

Hexane, the common solvent for extraction of edible oils from seeds is no more considered safe due to the presence of solvent in oil and also solvent vapour, a hazardous air pollutant. We have carried out the experiments with bahera (Terminalia bellerica Roxb) and flax seed (Linum usitatissimum ) oil as these oils are highly used in food for their

D. Bera; D. Lahiri; Antonella De Leonardis; K. B. De; A. Nag

23

Method for removing organic liquids from aqueous solutions and mixtures  

DOEpatents

A method for removing organic liquids from aqueous solutions and mixtures. The method employs any porous material preferably in granular form and having small pores and a large specific surface area, that is hydrophobic so that liquid water does not readily wet its surface. In this method, organics, especially organic solvents that mix with and are more volatile than water, are separated from aqueous solution by preferentially evaporating across the liquid/solid boundary formed at the surfaces of the hydrophobic porous materials. Also, organic solvents that are immiscible with water, preferentially wet the surfaces of the hydrophobic material and are drawn within the porous materials by capillary action.

Hrubesh, Lawrence W.; Coronado, Paul R.; Dow, Jerome P.

2004-03-23

24

Supporting Information Chemical Analysis of Complex Organic Mixtures Using Reactive  

E-print Network

Supporting Information Chemical Analysis of Complex Organic Mixtures Using Reactive Nanospray, PTFE) ring supported membranes of 47 mm diameter (Whatman, Inc.) using a rotating Micro- Orifice Uniform Deposit Impactor (MOUDI), model 110R (MSP, Inc). Collected LSOA material was distributed evenly

Nizkorodov, Sergey

25

ACUTE TOXICITY OF ORGANIC CHEMICAL MIXTURES TO THE FATHEAD MINNOW  

EPA Science Inventory

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

26

ATR spectra on boundary with mixture containing organic substances  

NASA Astrophysics Data System (ADS)

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

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

2005-02-01

27

Self-Organizing Maps, Vector Quantization, and Mixture Modeling  

E-print Network

|Self-organizing maps are popular algorithms for unsupervised learning and data visualization. Exploiting the link between vector quantization and mixture modeling, we derive EM algorithms for self-organizing maps with and without missing values. We compare self-organizing maps with the elastic-net approach and explain why the former is better suited for the visualization of high-dimensional data. Several extensions and improvements are discussed. As an illustration we apply a self-organizing map based on a multinomial distribution to market basket analysis. I. Introduction Self-organizing maps are popular tools for clustering and visualization of high-dimensional data [1], [2]. The wellknown Kohonen learning algorithm can be interpreted as a variant of vector quantization with additional lateral interactions [3], [4]. The addition of lateral interaction between units introduces a sense of topology, such that neighboring units represent inputs that are close together in input space [...

2001-01-01

28

Health and environmental research on complex organic mixtures: Proceedings  

SciTech Connect

During the preceding decade, numerous studies involving chemists, biologists, environmental scientists, industrial hygienists and engineers were conducted to assess the potential harmful effects of various complex organic mixtures. As a result, a substantial health and environmental database had been developed on combustion products, coal conversion materials (liquefaction and gasification), shale oils, petroleum, solid wastes, dredging spoils, materials from biomass, and other organic materials. Selection of the symposium topic reflected a desire to evaluate results of studies on materials from energy-related and industrial activities that could cause potential occupational problems or enter the environment. The symposium was organized to review and summarize the chemical, biomedical, and environmental database on complex organic mixtures. The program also provided a forum to identify future health and environmental research needs, coordinate present and future health and environmental research with technology development, and identify ways to mitigate problems associated with the release of energy-related materials to the environment. Individual papers were processed separately for the data base.

Gray, R.H.; Chess, E.K.; Mellinger, P.J.; Riley, R.G.; Springer, D.L. (eds.)

1987-01-01

29

Exposure of humans to a volatile organic mixture. 2. Sensory  

SciTech Connect

Time-course functions for symptoms of the sick building syndrome were derived from 66 healthy males exposed to clean air and a volatile organic compound (VOC) mixture in separate sessions. The mixture contained 22 VOCs (25 mg/cu m total concentration) commonly found air-borne in new or recently renovated buildings. Subjects rated the intensity of perceived irritation, odor, and other variables before and twice during 2.75 hr exposure periods. Eye and throat irritation, headache, and drowsiness increased or showed no evidence of adaptation during exposure, whereas odor intensity decreased by 30%. These results indicate that irritation intensity and other symptoms are not related in any simple fashion to odor intensity, suggesting that the symptoms may not be a psychosomatic response to detection of an aversive odor. Instead, subthreshold levels of VOCs may interact additively or hyperadditively and stimulate trigeminal nerve receptors.

Hudnell, H.K.; Otto, D.A.; House, D.E.; Molhave, L.

1992-01-01

30

Predicting flammability of gas mixtures containing volatile organic compounds  

SciTech Connect

One requirement regarding the transportation of transuranic (TRU) radioactive waste containers currently limits the total concentration of potentially flammable volatile organic compounds (VOCs) and flammable gases in the headspace of the waste container. Typical VOCs observed in the drums include aromatic hydrocarbons, ketones, alcohols, cyclohexane, as well as chlorinated hydrocarbons (alkanes and alkenes). Flammable gases, such as hydrogen and methane, may be generated in the containers by radiation-induced decomposition (radiolysis) of water and hydrocarbon waste forms. An experimental program was initiated to identify an accurate means for predicting flammability for gas mixtures containing one or more of the following species: hydrogen, carbon tetrachloride, 1,2-dichloroethane, toluene, or 2-butanone. The lower flammability limits (LFL) of gas mixtures containing equimolar quantity for each species were determined in a 19-liter laboratory flammability chamber using a strong spark ignition source. The group factor contribution method was determined to be more accurate than the LeChatelier method for estimating the LFL for these gas mixtures.

Liekhus, K. [Lockheed Martin Idaho Technologies Co., Idaho Falls, ID (United States). Idaho National Engineering and Environmental Lab.; Zlochower, I. [National Inst. for Occupational Safety and Health, Pittsburgh, PA (United States). Pittsburgh Research Lab.; Djordjevic, S.; Loehr, C. [Benchmark Environmental, Albuquerque, NM (United States)

1997-12-31

31

How will Primary and Secondary Organic Mixtures Impact CCN?  

NASA Astrophysics Data System (ADS)

As organic particles age, they may enhance their ability to uptake water, activate and form cloud droplets. These particles that activate are called cloud condensation nuclei (CCN). Understanding the chemical and thermodynamic properties that control CCN activity and droplet growth is necessary for constraining impacts on the hydrological cycle and uncertainties from the aerosol indirect effect. In particular, quantifying the effects of changes in partitioning and aging are important for predicting CCN concentrations. In our study we investigate changes in the CCN activity of biogenic secondary organic aerosol (SOA) modified by the presence of two anthropogenic two types of primary organic aerosol (POA) that are emitted by anthropogenic sources; POA from a flash vaporized mixture of motor-oil and fuel and POA emitted by a diesel engine. The aerosol are sampled from a 12 meter-cubed chamber and an Aerodyne quadrapole aerosol mass spectrometer (Q-AMS) measures changes in aerosol chemical composition and a continuous flow thermal gradient CCN counter measures CCN activity at different instrument supersaturations. We present the CCN activity of alpha-pinene SOA, motor-oil fuel and diesel exhaust POA and their subsequent mixtures. Alpha-pinene SOA is moderately CCN active and the POA that contain lubricating oil components are significantly less active. CCN measurements are compared with mass spectra to identify correlations in the data sets. CCN concentrations are predicted using Q-AMS chemical composition data; particle time of flight data is used to infer the aerosol mixing state and size-resolved CCN predictions are compared to measurements. The assumption that CCN properties are additive is tested by applying CCN properties of individual species to data from mixing experiments.

Asa-Awuku, A. A.; Donahue, N. M.; Robinson, A. L.

2009-12-01

32

SOIL SORPTION OF VOLATILE AND SEMIVOLATILE ORGANIC COMPOUNDS IN A MIXTURE  

EPA Science Inventory

Studies were conducted to evaluate lipophilicity as a predictor sorption for a mixture of organic compounds with high vapor pressures commonly present at hazardous waste sites. Sorption partition coefficients (Kp) for the mixture of 16 volatile and semivolatile ...

33

The effect of azeotropism on combustion characteristics of blended fuel pool fire.  

PubMed

The effect of azeotropism on combustion characteristics of blended fuel pool fire was experimentally studied in an open fire test space of State Key Laboratory of Fire Science. A 30 cm × 30 cm square pool filled with n-heptane and ethanol blended fuel was employed. Flame images, burning rate and temperature distribution were collected and recorded in the whole combustion process. Results show that azeotropism obviously dominates the combustion behavior of n-heptane/ethanol blended fuel pool fire. The combustion process after ignition exhibits four typical stages: initial development, azeotropic burning, single-component burning and decay stage. Azeotropism appears when temperature of fuel surface reaches azeotropic point and blended fuel burns at azeotropic ratio. Compared with individual pure fuel, the effect of azeotropism on main fire parameters, such as flame height, burning rate, flame puffing frequency and centerline temperature were analyzed. Burning rate and centerline temperature of blended fuel are higher than that of individual pure fuel respectively at azeotropic burning stage, and flame puffing frequency follows the empirical formula between Strouhal and Froude number for pure fuel. PMID:24632362

Ding, Yanming; Wang, Changjian; Lu, Shouxiang

2014-04-30

34

Dividing wall columns for heterogeneous azeotropic distillation Quang-Khoa Le1  

E-print Network

Dividing wall columns for heterogeneous azeotropic distillation Quang-Khoa Le1 , Ivar J. Halvorsen2 of this work is to implement heterogeneous azeotropic distillation schemes in a dividing wall column (DWC distillation, Petlyuk arrangement, energy saving. 1. Introduction Distillation is one of the most energy

Skogestad, Sigurd

35

Control of Meloidogyne incognita Using Mixtures of Organic Acids  

PubMed Central

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

Seo, Yunhee; Kim, Young Ho

2014-01-01

36

Control of Meloidogyne incognita Using Mixtures of Organic Acids.  

PubMed

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

Seo, Yunhee; Kim, Young Ho

2014-12-01

37

SOIL SORPTION OF VOLATILE AND SEMIVOLATILE ORGANIC COMPOUNDS IN A MIXTURE  

EPA Science Inventory

Studies were conducted to evaluate lipophilicity as a predictor of sorption for a mixture of organic compounds with high vapor pressures commonly present at hazardous waste sites. orption partition coefficients (Kp) for the mixture of 16 volatile and semivolatile organic compound...

38

Application of the Firefly and Luus-Jaakola algorithms in the calculation of a double reactive azeotrope  

NASA Astrophysics Data System (ADS)

The calculation of reactive azeotropes is an important task in the preliminary design and simulation of reactive distillation columns. Classically, homogeneous nonreactive azeotropes are vapor-liquid coexistence conditions where phase compositions are equal. For homogeneous reactive azeotropes, simultaneous phase and chemical equilibria occur concomitantly with equality of compositions (in the Ung-Doherty transformed space). The modeling of reactive azeotrope calculation is represented by a nonlinear algebraic system with phase equilibrium, chemical equilibrium and azeotropy equations. This nonlinear system can exhibit more than one solution, corresponding to a double reactive azeotrope. In a previous paper (Platt et al 2013 J. Phys.: Conf. Ser. 410 012020), we investigated some numerical aspects of the calculation of reactive azeotropes in the isobutene + methanol + methyl-tert-butyl-ether (with two reactive azeotropes) system using two metaheuristics: the Luus-Jaakola adaptive random search and the Firefly algorithm. Here, we use a hybrid structure (stochastic + deterministic) in order to produce accurate results for both azeotropes. After identifying the neighborhood of the reactive azeotrope, the nonlinear algebraic system is solved using Newton's method. The results indicate that using metaheuristics and some techniques devoted to the calculation of multiple minima allows both azeotropic coordinates in this reactive system to be obtains. In this sense, we provide a comprehensive analysis of a useful framework devoted to solving nonlinear systems, particularly in phase equilibrium problems.

Mendes Platt, Gustavo; Pinheiro Domingos, Roberto; Oliveira de Andrade, Matheus

2014-01-01

39

Supercritical extraction of organic mixtures from soil-water slurries  

E-print Network

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

Green, Lynda Ann

1994-01-01

40

Membrane permeation process for dehydration of organic liquid mixtures using sulfonated ion-exchange polyalkene membranes  

DOEpatents

A membrane permeation process for dehydrating a mixture of organic liquids, such as alcohols or close boiling, heat sensitive mixtures. The process comprises causing a component of the mixture to selectively sorb into one side of sulfonated ion-exchange polyalkene (e.g., polyethylene) membranes and selectively diffuse or flow therethrough, and then desorbing the component into a gas or liquid phase on the other side of the membranes.

Cabasso, Israel (131 Buckingham Ave., Syracuse, NY 13210); Korngold, Emmanuel (P.O. Box 1025, Beer-Sheva 84110, IL)

1988-01-01

41

Processes of Heat Transfer in Rheologically Unstable Mixtures of Organic Origin  

NASA Astrophysics Data System (ADS)

The dependence of the coefficient of heat transfer from the heat-exchange surface to a rheologically unstable organic mixture on the thermohydrodynamic state of the mixture and its prehistory has been established. A method for multivariant investigation of the process of heat transfer in compound organic mixtures has been proposed; this method makes it possible to evaluate the character and peculiarities of change in the rheological structure of the mixture as functions of the thermohydrodynamic conditions of its treatment. The possibility of evaluating the intensity of heat transfer in a biotechnological system for production of energy carriers at the step of its designing by multivariant investigation of the heat-transfer intensity in rheologically unstable organic mixtures with account of their prehistory has been shown.

Tkachenko, S. I.; Pishenina, N. V.; Rumyantseva, T. Yu.

2014-05-01

42

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

EPA Science Inventory

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

43

Parameters for the Pyrolysis of Organic Material - Perchlorate Mixtures  

NASA Astrophysics Data System (ADS)

The ESA-lead Mars rover ExoMars (launch in 2018) will carry a suit of instruments, one of the in-struments is the Mars Organic Molecule Analyzer MOMA. Organic material in the Martian soil will be either pyrolyzed at temperatures of up to 1000°C and separated by gas chromatography or volatilized with the help of an UV-laser. A mass spectrometer will be the detector for both methods. Chlorinated organics have been detected in pyroly-sis GC-MS experiments on Mars two times. The first time during the Viking mission in 1976 and a second time with the Sample Analysis on Mars (SAM) in-strument onboard the Curiosity rover in 2012. [1] [2] The presence of perchlorates found by the Phoenix mission in 2008 [3] lead to the discovery that organic molecules not only get oxidized during pyrolysis, but also chlorinated organic compounds can be pro-duced. [4] The parameters used for pyrolysis and the sample composition especially the distribution of organics and perchlorates within the sample and the concentrations of organics and perchlorate have a huge influence on the products created. It is possible to change the condi-tions of the pyrolysis by spatially separating the organ-ics from the perchlorates that the chloromethanes get the major product of the pyrolysis. This might help to understand the results of the (SAM) instrument yield-ing mono-, di- and trichloromethane and a chlorinated 4-hydrocarbon molecule. References: [1] Biemann K et al. (1977) JGR, 82, 4641-4658. [2] Grotzinger J. P et al. (2011) AGU Fall Meeting U13A-01 [3] Hecht M. H., et al. (2009) Science, 325 64-67. [4] Steininger H., Goesmann F., Goetz W. (2011) Planet. & Space Sci., 71, 9-17. Acknowledgments: This work was funded by DLR (FKZ 50QX1001)

Steininger, Harald; Goesmann, Fred; Goetz, Walter

2013-04-01

44

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

EPA Science Inventory

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

45

DESIGNING FIXED-BED ADSORBERS TO REMOVE MIXTURES OF ORGANICS.  

EPA Science Inventory

A liquid-phase granular activated carbon (GAC) pilot plant and a full-scale GAC adsorber were designed, built, and operated in order to evaluate their performance for treating a groundwater contaminated with several volatile and synthetic organic chemicals. Several empty bed con...

46

EXPOSURE OF HUMANS TO VOLATILE ORGANIC MIXTURE. III. INFLAMMATORY RESPONSE  

EPA Science Inventory

A set of symptoms has been described during the past two decades which has been called the "sick building syndrome." hese symptoms include eye, nose, and throat irritation; headache; mental fatigue; and respiratory distress. t is likely that volatile organic compounds (VOC) prese...

47

Mass transfer characteristics in a large-scale slurry bubble column reactor with organic liquid mixtures  

Microsoft Academic Search

The mass transfer coefficients (kLa) and bubbles size distribution were measured in a large-scale (0.316-m inside diameter, 2.8-m high) slurry bubble column reactor (SBCR) for H2, CO, N2 and CH4 in two organic liquid mixtures (Isopar-M and a hexanes mixture) in the presence and absence of two solids (iron oxides catalyst and glass beads) in a wide range of pressure

Arsam Behkish; Zhuowu Men; Juan R. Inga; Badie I. Morsi

2002-01-01

48

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

SciTech Connect

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

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

1998-07-01

49

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

50

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

SciTech Connect

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

MARUSICH, R.M.

2006-07-10

51

Azeotropic distillation assisted fabrication of silver nanocages and their catalytic property for reduction of 4-nitrophenol.  

PubMed

Monodisperse silver nanocages (AgNCs) with specific interiors were successfully synthesized by an azeotropic distillation (AD) assisted method and exhibited excellent catalytic activities for reduction of 4-nitrophenol (4-NP) into 4-aminophenol (4-AP) due to the unique hollow morphology and small thickness of the silver shell. PMID:25421649

Min, Jianzhong; Wang, Fei; Cai, Yunliang; Liang, Shuai; Zhang, Zhenwei; Jiang, Xingmao

2015-01-14

52

Exposure of humans to a volatile organic mixture. 1. Behavioral assessment  

SciTech Connect

Exposure to a low-level mixture of volatile organic compounds, typical of those found in new buildings, has been reported to impair neurobehavioral function in persons who have experienced sick building syndrome (SBS). Sixty-six healthy young males who had no history of chemical sensitivity were exposed for 2.75 h to a complex mixture of volatile organic compounds at 0 and 25 mg/cu m. Even though subjects reported more fatigue and more mental confusion following exposure to volatile organic compounds than to clean air, performance on 13 neurobehavioral tests was not affected. Practice or learning effects were observed if administration of many behavioral tests were repeated. Further studies are needed to clarify the relationship of exposure to volatile organic chemicals, neurobehavioral performance, and subject characteristics, e.g., age, gender, and chemical sensitivity.

Otto, D.A.; Hudnell, H.K.; House, D.E.; Moelhave, L.; Counts, W.

1991-01-01

53

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

ERIC Educational Resources Information Center

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

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

2007-01-01

54

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

EPA Science Inventory

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

55

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

PubMed Central

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

Mazurek, Monica A

2002-01-01

56

MIXTURE EFFECTS IN THE CATALYTIC OXIDATION OF VOCS (VOLATILE ORGANIC COMPOUNDS) IN AIR  

EPA Science Inventory

The report gives results of a study of the deep oxidation of organic mixtures over a heterogeneous catalyst in an attempt to explain earlier observations concerning the apparent inhibition or enhancement of destruction of some components to establish a scientific basis for the de...

57

Improved AIOMFAC model parameterisation of the temperature dependence of activity coefficients for aqueous organic mixtures  

NASA Astrophysics Data System (ADS)

This study presents a new, improved parameterisation of the temperature dependence of activity coefficients in the AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients) model applicable for aqueous as well as water-free organic solutions. For electrolyte-free organic and organic-water mixtures the AIOMFAC model uses a group-contribution approach based on UNIFAC (UNIversal quasi-chemical Functional-group Activity Coefficients). This group-contribution approach explicitly accounts for interactions among organic functional groups and between organic functional groups and water. The previous AIOMFAC version uses a simple parameterisation of the temperature dependence of activity coefficients, aimed to be applicable in the temperature range from ~275 to ~400 K. With the goal to improve the description of a wide variety of organic compounds found in atmospheric aerosols, we extend the AIOMFAC parameterisation for the functional groups carboxyl, hydroxyl, ketone, aldehyde, ether, ester, alkyl, aromatic carbon-alcohol, and aromatic hydrocarbon to atmospherically relevant low temperatures with the introduction of a new temperature dependence parameterisation. The improved temperature dependence parameterisation is derived from classical thermodynamic theory by describing effects from changes in molar enthalpy and heat capacity of a multicomponent system. Thermodynamic equilibrium data of aqueous organic and water-free organic mixtures from the literature are carefully assessed and complemented with new measurements to establish a comprehensive database, covering a wide temperature range (~190 to ~440 K) for many of the functional group combinations considered. Different experimental data types and their processing for the estimation of AIOMFAC model parameters are discussed. The new AIOMFAC parameterisation for the temperature dependence of activity coefficients from low to high temperatures shows an overall improvement of 25% in comparison to the previous model version. The new parameterisation of AIOMFAC agrees well with a large number of experimental datasets and enables the calculation of activity coefficients of a wide variety of different aqueous/water-free organic solutions down to the low temperatures present in the upper troposphere.

Ganbavale, G.; Zuend, A.; Marcolli, C.; Peter, T.

2014-06-01

58

Adsorption and desorption of mixtures of organic vapors on beaded activated carbon.  

PubMed

In this study, adsorption and desorption of mixtures of organic compounds commonly emitted from automotive painting operations were experimentally studied. A mixture of two alkanes and a mixture of eight organic compounds were adsorbed onto beaded activated carbon (BAC) and then thermally desorbed under nitrogen. Following both adsorption and regeneration, samples of the BAC were chemically extracted. Gas chromatography-mass spectrometry (GC-MS) was used to quantify the compounds in the adsorption and desorption gas streams and in the BAC extracts. In general, for both adsorbate mixtures, competitive adsorption resulted in displacing low boiling point compounds by high boiling point compounds during adsorption. In addition to boiling point, adsorbate structure and functionality affected adsorption dynamics. High boiling point compounds such as n-decane and 2,2-dimethylpropylbenzene were not completely desorbed after three hours regeneration at 288 °C indicating that these two compounds contributed to heel accumulation on the BAC. Additional compounds not present in the mixtures were detected in the extract of regenerated BAC possibly due to decomposition or other reactions during regeneration. Closure analysis based on breakthrough curves, solvent extraction of BAC and mass balance on the reactor provided consistent results of the amount of adsorbates on the BAC after adsorption and/or regeneration. PMID:22742925

Wang, Haiyan; Jahandar Lashaki, Masoud; Fayaz, Mohammadreza; Hashisho, Zaher; Philips, John H; Anderson, James E; Nichols, Mark

2012-08-01

59

Comparison of activity coefficient models for atmospheric aerosols containing mixtures of electrolytes, organics, and water  

NASA Astrophysics Data System (ADS)

Atmospheric aerosols generally comprise a mixture of electrolytes, organic compounds, and water. Determining the gas-particle distribution of volatile compounds, including water, requires equilibrium or mass transfer calculations, at the heart of which are models for the activity coefficients of the particle-phase components. We evaluate here the performance of four recent activity coefficient models developed for electrolyte/organic/water mixtures typical of atmospheric aerosols. Two of the models, the CSB model [Clegg, S.L., Seinfeld, J.H., Brimblecombe, P., 2001. Thermodynamic modelling of aqueous aerosols containing electrolytes and dissolved organic compounds. Journal of Aerosol Science 32, 713-738] and the aerosol diameter dependent equilibrium model (ADDEM) [Topping, D.O., McFiggans, G.B., Coe, H., 2005. A curved multi-component aerosol hygroscopicity model framework: part 2—including organic compounds. Atmospheric Chemistry and Physics 5, 1223-1242] treat ion-water and organic-water interactions but do not include ion-organic interactions; these can be referred to as "decoupled" models. The other two models, reparameterized Ming and Russell model 2005 [Raatikainen, T., Laaksonen, A., 2005. Application of several activity coefficient models to water-organic-electrolyte aerosols of atmospheric interest. Atmospheric Chemistry and Physics 5, 2475-2495] and X-UNIFAC.3 [Erdakos, G.B., Change, E.I., Pandow, J.F., Seinfeld, J.H., 2006. Prediction of activity coefficients in liquid aerosol particles containing organic compounds, dissolved inorganic salts, and water—Part 3: Organic compounds, water, and ionic constituents by consideration of short-, mid-, and long-range effects using X-UNIFAC.3. Atmospheric Environment 40, 6437-6452], include ion-organic interactions; these are referred to as "coupled" models. We address the question—Does the inclusion of a treatment of ion-organic interactions substantially improve the performance of the coupled models over that of the decoupled models? Performance is judged by the extent to which each model is able to reproduce experimental water activity data for mixtures of organic acids (malonic, succinic, glutaric, citric, maleic, and malic acids) and inorganic electrolytes (NaCl and (NH 4) 2SO 4). It is found, based on the comparisons reported here, that the decoupled models perform as well as, and in some cases better than, the coupled models. Since such activity coefficient models are likely to continue to be developed in the future and because we consider here only a limited set of organic compounds, the current study should be viewed as an interim assessment. The scarcity of experimental data for mixtures of atmospheric relevance remains a limitation for testing activity coefficient models.

Tong, Chinghang; Clegg, Simon L.; Seinfeld, John H.

60

Effect of gamma irradiation on a PCB mixture in organic solvent  

SciTech Connect

Gamma irradiation is a food preservation process that can alter the relative proportions of PCB congeners in a PCB mixture. The objectives of this study were two fold. First, to assess the effects of small doses of gamma irradiation on the PCB mixture profile in various organic solvents used as model systems for PCB residues in food irradiated with gamma rays. Second, to investigate the fate of some toxic congeners such as congener 77, 126 and 169 (according to Ballschmiter nomenclature) and some of their toxic mono-ortho substituted congeners.

Lepine, F. (Armand-Frappier Institute, Laval, Quebec (Canada)); Masse, R. (Institut National de la Recherche Scientifique, Pointe-Claire, Quebec (Canada))

1990-04-01

61

Modeling the surface tension of complex, reactive organic-inorganic mixtures  

NASA Astrophysics Data System (ADS)

Atmospheric aerosols can contain thousands of organic compounds which impact aerosol surface tension, affecting aerosol properties such as heterogeneous reactivity, ice nucleation, and cloud droplet formation. We present new experimental data for the surface tension of complex, reactive organic-inorganic aqueous mixtures mimicking tropospheric aerosols. Each solution contained 2-6 organic compounds, including methylglyoxal, glyoxal, formaldehyde, acetaldehyde, oxalic acid, succinic acid, leucine, alanine, glycine, and serine, with and without ammonium sulfate. We test two semi-empirical surface tension models and find that most reactive, complex, aqueous organic mixtures which do not contain salt are well described by a weighted Szyszkowski-Langmuir (S-L) model which was first presented by Henning et al. (2005). Two approaches for modeling the effects of salt were tested: (1) the Tuckermann approach (an extension of the Henning model with an additional explicit salt term), and (2) a new implicit method proposed here which employs experimental surface tension data obtained for each organic species in the presence of salt used with the Henning model. We recommend the use of method (2) for surface tension modeling of aerosol systems because the Henning model (using data obtained from organic-inorganic systems) and Tuckermann approach provide similar modeling results and goodness-of-fit (?2) values, yet the Henning model is a simpler and more physical approach to modeling the effects of salt, requiring less empirically determined parameters.

Schwier, A. N.; Viglione, G. A.; Li, Z.; McNeill, V. Faye

2013-11-01

62

Modeling the surface tension of complex, reactive organic-inorganic mixtures  

NASA Astrophysics Data System (ADS)

Atmospheric aerosols can contain thousands of organic compounds which impact aerosol surface tension, affecting aerosol properties such as cloud condensation nuclei (CCN) ability. We present new experimental data for the surface tension of complex, reactive organic-inorganic aqueous mixtures mimicking tropospheric aerosols. Each solution contained 2-6 organic compounds, including methylglyoxal, glyoxal, formaldehyde, acetaldehyde, oxalic acid, succinic acid, leucine, alanine, glycine, and serine, with and without ammonium sulfate. We test two surface tension models and find that most reactive, complex, aqueous organic mixtures which do not contain salt are well-described by a weighted Szyszkowski-Langmuir (S-L) model which was first presented by Henning et al. (2005). Two approaches for modeling the effects of salt were tested: (1) the Tuckermann approach (an extension of the Henning model with an additional explicit salt term), and (2) a new implicit method proposed here which employs experimental surface tension data obtained for each organic species in the presence of salt used with the Henning model. We recommend the use of method (2) for surface tension modeling because the Henning model (using data obtained from organic-inorganic systems) and Tuckermann approach provide similar modeling fits and goodness of fit (?2) values, yet the Henning model is a simpler and more physical approach to modeling the effects of salt, requiring less empirically determined parameters.

Schwier, A. N.; Viglione, G. A.; Li, Z.; McNeill, V. F.

2013-01-01

63

Pervaporation performance of a composite bacterial cellulose membrane: dehydration of binary aqueous–organic mixtures  

Microsoft Academic Search

Summary  \\u000a Acetobacter xylinum (Gluconacetobacter xylinus) is a bacterium that produces extracellular cellulose under static culture conditions. The highly reticulated cellulose matrix\\u000a along with the entrapped cellulose-forming bacteria is commonly referred to as a pellicle. The processed bacterial cellulose\\u000a membrane\\/film was modified into a composite bacterial cellulose membrane (CBCM) for pervaporation separation of aqueous–organic\\u000a mixtures. The CBCM was prepared by coating

K. V. Ramana; K. Ganesan; Lokendra Singh

2006-01-01

64

Separation and molecular-level segregation of complex alkane mixtures in metal-organic frameworks.  

PubMed

In this computational work we explore metal-organic frameworks (MOFs) for separating alkanes according to the degree of branching. We show that the structure MOF-1 shows an adsorption hierarchy for a 13-component light naphtha mixture precisely as desired for increasing the research octane number of gasoline. In addition we report an unusual molecular-level segregation of molecules based on their degree of branching. PMID:18651737

Dubbeldam, David; Galvin, Casey J; Walton, Krista S; Ellis, Donald E; Snurr, Randall Q

2008-08-20

65

Ceramic-supported polymer membranes for pervaporation of binary organic\\/organic mixtures  

Microsoft Academic Search

Asymmetric tubular alumina-supported poly(vinyl acetate) (PVAc) and poly(vinyl pyrrolidone) (PVP) membranes were created and characterized by pervaporation separation of binary mixtures of methanol and methyl tert-butyl ether (MTBE). The active separation layer was created by free-radical graft polymerization of PVAc and PVP onto a vinylsilane-modified alumina substrate with an average native pore diameter of 50Å. The separation layer consisted of

Wayne Yoshida; Yoram Cohen

2003-01-01

66

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

SciTech Connect

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

Kujawski, W.

2000-01-01

67

Synthesis and characteristics of nanocrystalline YSZ powder by polyethylene glycol assisted coprecipitation combined with azeotropic-distillation process and its electrical conductivity  

Microsoft Academic Search

Nanoscale 8 mol% yttria stabilized zirconia (YSZ) powders were prepared by polyethylene glycol (PEG-1540) assisted coprecipitation coupling with azeotropic distillation drying process. The role of PEG and azeotropic-distillation on the morphology and particle size of YSZ was studied. Thermogravimetry and X-ray diffraction results showed that azeotropic-distillation could reduce the formation temperature of YSZ phase. X-ray patterns of the YSZ powders

Hong-Chang Yao; Xian-Wei Wang; Hao Dong; Rui-Rui Pei; Jian-She Wang; Zhong-Jun Li

2011-01-01

68

Microbial detection of mutagenic nitro-organic compounds in filtrates of coal fly ash  

SciTech Connect

The presence of mutagenic nitro-organic compounds on coal fly ash was indicated by the greatly reduced microbial mutagenicity of the ash filtrates with nitroreductase-deficient strains of Salmonella typhimurium compared to their corresponding parental strains. Addition of the liver S-9 microsomal enzyme preparation significantly increased the mutagenic activities of the ash extracts. Extracts of fly ash mutagens were prepared with horse serum, dimethyl sulfoxide, or azeotropic benzene/methanol mixture. The data were normalized to net revertants per 10/sup 8/ Salmonella typhimurium cells per milligram of ash used. This normalization procedure is essential for interpretation of comparative results. Both four-way and three-way analyses of variance were used to simultaneously evaluate the differences between solvent extracts, fly ash mutagen, S-9 activation, and nitroreductase-deficient strains and their parental strains. Of the three extraction systems tested, benzene/methanol azeotropic mixture was generally found to have the highest extraction power, and horse serum was the lowest. The results show that overall 87.5% (+/- 1.8 SE) of the mutagenic activity of the fly ash was associated with nitro-organic compounds.

Wei, C. (Univ. of California, Davis); Raabe, O.G.; Rosenblatt, L.S.

1982-01-01

69

Energy transfer studies in binary laser dye mixtures in organically modified silicates  

NASA Astrophysics Data System (ADS)

Energy transfer of binary dye mixture (Rhodamine110, as donor, and Oxizine1and/or Nile blue as acceptors) doped in organically modified silicates (ORMOSILs) matrix has been studied. The energy transfer process from donor molecules to acceptor molecules in the final bulk samples has been observed spectrally. Some of energy transfer parameters have been determined as a function of acceptor concentration. Stern-Volmer relation of energy transfer has been proved and the dominant mechanism of the energy transfer of dye mixture doped in such matrices has been determined. The results show that the emission properties of acceptor molecules (Ox1 and Nb) can be enhanced using the dye mixing recipe in sol-gel matrices.

Al-Maliki, Firas J.

2014-08-01

70

Secondary organic aerosol formation from ozone reactions with single terpenoids and terpenoid mixtures  

NASA Astrophysics Data System (ADS)

Ozone reacts with indoor-emitted terpenoids to form secondary organic aerosol (SOA). Most SOA research has focused on ozone reactions with single terpenoids or with consumer products, and this paper reports the results from an investigation of SOA formation from ozone reactions with both single terpenoids and mixtures of D-limonene, ?-pinene, and ?-terpineol. Transient experiments were conducted at low (25 ppb) and high (100 ppb) initial concentrations of ozone. The three terpenoids were tested singly and in combinations in a manner that controlled for their different reaction rates with ozone. The SOA formation was assessed by examining the evolution in time of the resulting number size-distributions and estimates of the mass concentrations. The results suggest that at higher ozone and terpenoid concentrations, SOA number formation follows a linear trend as a function of the initial rate of reaction. This finding was valid for both single terpenoids and mixtures. Generally speaking, higher ozone and terpenoid concentrations also led to larger geometric mean diameters and smaller geometric standard deviations of fitted lognormal distributions of the formed SOA. By assuming a density, mass concentrations were also assessed and did not follow as consistent of a trend. At low ozone concentration conditions, reactions with only D-limonene yielded the largest number concentrations of any experiment, even more than experiments with mixtures containing D-limonene and much higher overall terpenoid concentrations. This finding was not seen for high ozone concentrations. These experiments demonstrate quantifiable trends for SOA forming reactions of ozone and mixtures, and this work provides a framework for expanding these results to more complex mixtures and consumer products.

Waring, Michael S.; Wells, J. Raymond; Siegel, Jeffrey A.

2011-08-01

71

Plasmas and Polymers, Vol. 5, Nos. 3/4, 2000 Synthesis of Organic Compounds from Mixtures of  

E-print Network

Plasmas and Polymers, Vol. 5, Nos. 3/4, 2000 Synthesis of Organic Compounds from Mixtures gases; polymer films; dielectric-barrier discharge; organic synthesis. 1. INTRODUCTION The first hydrocarbons and oxygenated organic compounds). The macro-kinetics of the basic chemical pathways of the system

Greifswald, Ernst-Moritz-Arndt-Universität

72

Improved AIOMFAC model parameterisation of the temperature dependence of activity coefficients for aqueous organic mixtures  

NASA Astrophysics Data System (ADS)

This study presents a new, improved parameterisation of the temperature dependence of activity coefficients in the AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients) model applicable for aqueous as well as water-free organic solutions. For electrolyte-free organic and organic-water mixtures the AIOMFAC model uses a group-contribution approach based on UNIFAC (UNIversal quasi-chemical Functional-group Activity Coefficients). This group-contribution approach explicitly accounts for interactions among organic functional groups and between organic functional groups and water. The previous AIOMFAC version uses a simple parameterisation of the temperature dependence of activity coefficients, aimed to be applicable in the temperature range from ~ 275 to ~ 400 K. With the goal to improve the description of a wide variety of organic compounds found in atmospheric aerosols, we extend the AIOMFAC parameterisation for the functional groups carboxyl, hydroxyl, ketone, aldehyde, ether, ester, alkyl, aromatic carbon-alcohol, and aromatic hydrocarbon to atmospherically relevant low temperatures. To this end we introduce a new parameterisation for the temperature dependence. The improved temperature dependence parameterisation is derived from classical thermodynamic theory by describing effects from changes in molar enthalpy and heat capacity of a multi-component system. Thermodynamic equilibrium data of aqueous organic and water-free organic mixtures from the literature are carefully assessed and complemented with new measurements to establish a comprehensive database, covering a wide temperature range (~ 190 to ~ 440 K) for many of the functional group combinations considered. Different experimental data types and their processing for the estimation of AIOMFAC model parameters are discussed. The new AIOMFAC parameterisation for the temperature dependence of activity coefficients from low to high temperatures shows an overall improvement of 28% in comparison to the previous model version, when both versions are compared to our database of experimentally determined activity coefficients and related thermodynamic data. When comparing the previous and new AIOMFAC model parameterisations to the subsets of experimental data with all temperatures below 274 K or all temperatures above 322 K (i.e. outside a 25 K margin of the reference temperature of 298 K), applying the new parameterisation leads to 37% improvement in each of the two temperature ranges considered. The new parameterisation of AIOMFAC agrees well with a large number of experimental data sets. Larger model-measurement discrepancies were found particularly for some of the systems containing multi-functional organic compounds. The affected systems were typically also poorly represented at room temperature and further improvements will be necessary to achieve better performance of AIOMFAC in these cases (assuming the experimental data are reliable). The performance of the AIOMFAC parameterisation is typically better for systems containing relatively small organic compounds and larger deviations may occur in mixtures where molecules of high structural complexity such as highly oxygenated compounds or molecules of high molecular mass (e.g. oligomers) prevail. Nevertheless, the new parameterisation enables the calculation of activity coefficients for a wide variety of different aqueous/water-free organic solutions down to the low temperatures present in the upper troposphere.

Ganbavale, G.; Zuend, A.; Marcolli, C.; Peter, T.

2015-01-01

73

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

EPA Science Inventory

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

74

Organic tank safety project: Preliminary results of energetics and thermal behavior studies of model organic nitrate and/or nitrite mixtures and a simulated organic waste  

SciTech Connect

As a result of years of production and recovery of nuclear defense materials and subsequent waste management at the Hanford Site, organic-bearing radioactive high-level wastes (HLW) are currently stored in large (up to 3. ML) single-shell storage tanks (SSTs). Because these wastes contain both fuels (organics) and the oxidants nitrate and nitrite, rapid energetic reactions at certain conditions could occur. In support of Westinghouse Hanford Company`s (WHC) efforts to ensure continued safe storage of these organic- and oxidant-bearing wastes and to define the conditions necessary for reactions to occur, we measured the thermal sensitivities and thermochemical and thermokinetic properties of mixtures of selected organics and sodium nitrate and/or nitrite and a simulated Hanford organic-bearing waste using thermoanalytical technologies. These thermoanalytical technologies are used by chemical reactivity hazards evaluation organizations within the chemical industry to assess chemical reaction hazards.

Scheele, R.D.; Sell, R.L.; Sobolik, J.L.; Burger, L.L.

1995-08-01

75

Analysis of organic solvents and liquid mixtures using a fiber-tip evaporation sensor  

NASA Astrophysics Data System (ADS)

The instantaneous size and rate of evaporation of pendant liquid droplets placed on the cleaved facet of a standard fiber are reconstructed based on reflected optical power. Using the evaporation dynamics, the relative contents of ethanol in ethanol-water binary mixtures are assessed with 1% precision and different blends of methanol in gasoline are properly recognized. The latter application, in particular, is significant for the use of alternative fuels in the automotive sector. Also, ten organic solvents are identified based on their evaporation from a fiber facet coated with a hydrophobic, selfassembled monolayer.

Preter, Eyal; Donlagic, Denis; Artel, Vlada; Katims, Rachel A.; Sukenik, Chaim N.; Zadok, Avi

2014-05-01

76

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

Microsoft Academic Search

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

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

2010-01-01

77

Spectral editing of organic mixtures into pure components using NMR spectroscopy and ultraviscous solvents.  

PubMed

A general technique is described that permits the extraction of a complete 1H NMR spectrum for components in organosoluble mixtures. The approach should find a wide range of applications considering that pure component spectra can be generated without the need for physical separation. This technique is especially significant for synthetic organic chemistry and the pharmaceutical industry due to the potential to isolate a product spectrum even in the presence of overlapping starting materials, byproducts, or degradation products. A viscous oil-based solvent system that can be temperature-manipulated from essentially a solid at one extreme to a freely flowing liquid at the other is employed. The system contains no protons and is miscible with common organic solvents. Through careful control of the temperature and thus solvent viscosity, the behavior of small molecules moves from the positive to the extreme of the negative NOE regime. Under such conditions, all protons in a molecule correlate with all other protons as propagation by spin diffusion becomes highly efficient, behavior normally only observed with rigid macromolecules in conventional solvents. Therefore, as long as one proton (or carbon signal in hybrid experiments) is resolved for a component in a mixture, the entire proton spectrum for that molecule can be cleanly extracted from a 2D NOESY spectrum (or from selective 1D NOE-based analogues). Preliminary results are highly encouraging, indicating that the approach may be feasible for a wide range of molecules and mixtures; however, in practice the exact types of structures, combinations of structures, and range of concentrations that can be cleanly extracted will become evident as the technique becomes better established. PMID:18052233

Simpson, André J; Woods, Gwen; Mehrzad, Omid

2008-01-01

78

Characterization of secondary organic aerosol generated from ozonolysis of ?-pinene mixtures  

NASA Astrophysics Data System (ADS)

In the atmosphere, multiple volatile organic compounds (VOCs) co-exist, and they can be oxidized concurrently and generate secondary organic aerosol (SOA). In this work, SOA is formed by the oxidation (in presence of excess ozone) of mixtures containing ?-pinene and other VOCs. The VOC mixtures were made so their composition approached a commercially-available ?-pinene-based essential oil, Siberian fir needle oil. The SOA products were sampled using filters, solvent extracted and analyzed by gas chromatography/mass spectrometry with trimethylsilyl derivatization. The individual product yields for SOA generated from ?-pinene changed upon the addition of other VOCs. An increase in concentration of non-reactive VOCs (bornyl acetate, camphene, and borneol) lead to a decrease in individual product yields of characteristic ?-pinene SOA products. Although these experiments were carried out under higher VOC and ozone concentrations in comparison to the atmosphere, this work suggests that the role of non-reactive VOCs should be explored in SOA products formation.

Amin, Hardik S.; Hatfield, Meagan L.; Huff Hartz, Kara E.

2013-03-01

79

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

PubMed Central

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

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

2003-01-01

80

Effect of Exposure to a Mixture of Organic Solvents on Hearing Thresholds in Petrochemical Industry Workers  

PubMed Central

Introduction: Hearing loss is one of the most common occupational diseases. In most workplaces, workers are exposed to noise and solvents simultaneously, so the potential risk of hearing loss due to solvents may be attributed to noise. In this study we aimed to assess the effect of exposure to mixed aromatic solvents on hearing in the absence of exposure to hazardous noise. Materials and Methods: In a cross-sectional study, 99 workers from the petrochemical industry with exposure to a mixture of organic solvents whose noise exposure was lower than 85 dBA were compared with 100 un-exposed controls. After measuring sound pressure level and mean concentration of each solvent in the workplace, pure-tone-audiometry was performed and the two groups were compared in terms of high-frequency and low-frequency hearing loss. T-tests and Chi-square tests were used to compare the two groups. Results: The mean hearing threshold at all frequencies among petrochemical workers was normal (below 25 dB). We did not observe any significant association between solvent exposure and high-frequency or low-frequency hearing loss. Conclusion: This study showed that temporary exposure (less than 4 years) to a mixture of organic solvents, without exposure to noise, does not affect workers’ hearing threshold in audiometry tests. PMID:25320701

Loukzadeh, Ziba; Shojaoddiny-Ardekani, Ahmad; Mehrparvar, Amir Houshang; Yazdi, Zohreh; Mollasadeghi, Abolfazl

2014-01-01

81

Ionic equilibria in aqueous organic solvent mixtures the dissociation constants of acids and salts in tetrahydrofuran\\/water mixtures  

Microsoft Academic Search

The dissociation constants of several acids (perchloric, hydrochloric, phosphoric, acetic and benzoic acids) and of some sodium salts (chloride, acetate and benzoate) have been conductometrically determined in tetrahydrofuran\\/water mixtures up to a 90% of tetrahydrofuran in volume. The results demonstrate that conductometry can be successfully applied to determine the dissociation constants of salts and moderately weak and strong acids in

Urmas Muinasmaa; Clara Ràfols; Elisabeth Bosch; Martí Rosés

1997-01-01

82

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

PubMed

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

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

2015-02-01

83

IUPAC-NIST Solubility Data Series. 99. Solubility of Benzoic Acid and Substituted Benzoic Acids in Both Neat Organic Solvents and Organic Solvent Mixtures  

NASA Astrophysics Data System (ADS)

Solubility data are compiled and reviewed for benzoic acid and 63 substituted benzoic acids dissolved in neat organic solvents and well-defined binary and ternary organic solvent mixtures. The compiled solubility data were retrieved from the published chemical and pharmaceutical literature covering the period from 1900 to the beginning of 2013.

Acree, William E.

2013-09-01

84

Li+ solvation in pure, binary and ternary mixtures of organic carbonate electrolytes  

E-print Network

Classical molecular dynamics (MD) simulations and quantum chemical density functional theory (DFT) calculations have been employed in the present study to investigate the solvation of lithium cations in pure organic carbonate solvents (ethylene carbonate (EC), propylene carbonate (PC) and dimethyl carbonate (DMC)) and their binary (EC-DMC, 1:1 molar composition) and ternary (EC-DMC-PC, 1:1:3 molar composition) mixtures. The results obtained by both methods indicate that the formation of complexes with four solvent molecules around Li+, exhibiting a strong local tetrahedral order, is the most favorable. However, the molecular dynamics simulations have revealed the existence of significant structural heterogeneities, extending up to a length scale which is more than five times the size of the first coordination shell radius. Due to these significant structural fluctuations in the bulk liquid phases, the use of larger size clusters in DFT calculations has been suggested. Contrary to the findings of the DFT calcu...

Skarmoutsos, Ioannis; Vetere, Valentina; Mossa, Stefano

2014-01-01

85

Extraction of betulin, trimyristin, eugenol and carnosic acid using water-organic solvent mixtures.  

PubMed

A solvent system consisting of ethyl acetate, ethyl alcohol and water, in the volume ratio of 4.5:4.5:1, was developed and used to extract, at room temperature, betulin from white birch bark and antioxidants from spices (rosemary, thyme, sage, and oregano) and white oak chips. In addition, under reflux conditions, trimyristin was extracted from nutmeg using the same solvent system, and eugenol from olives was extracted using a mixture of salt water and ethyl acetate. The protocol demonstrates the use of water in organic solvents to extract natural products from plants. Measurement of the free-radical scavenging activity using by 2,2-diphenyl-1-picrylhydrazyl (DPPH) indicated that the extraction of plant material using ethyl acetate, ethyl alcohol and water (4.5:4.5:1, v/v/v) was exhaustive when carried out at room temperature for 96 h. PMID:22864237

Lugemwa, Fulgentius N

2012-01-01

86

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

87

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

PubMed

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

Siebielska, Izabela; Side?ko, Robert

2015-05-01

88

Determination of single photon ionization cross sections for quantitative analysis of complex organic mixtures.  

PubMed

Soft single photon ionization (SPI)-time-of-flight mass spectrometry (TOFMS) is well suited for fast and comprehensive analysis of complex organic gas mixtures, which has been demonstrated in various applications. This work describes a calibration scheme for SPI, which enables quantification of a large number of compounds by only calibrating one compound of choice, in this case benzene. Photoionization cross sections of 22 substances were determined and related to the yield of benzene. These substances included six alkanes (pentane, hexane, heptane, octane, nonane, decane), three alkenes (propene, butane, pentene), two alkynes (propyne, butyne), two dienes (butadiene, isoprene), five monoaromatic species (benzene, toluene, xylene, styrene, monochlorobenzene) and NO. The cross sections of organic compounds differ by about one order of magnitude but the photoionization properties of compounds belonging to one compound class are rather similar. Therefore, the scheme can also be used for an approximate quantification of compound classes. This is demonstrated by a fast characterization and pattern recognition of two gasoline samples with different origins (Germany and South Africa) and a diesel sample (Germany). The on-line capability of the technique and the scheme is demonstrated by quantitatively monitoring and comparing the cold engine start of four vehicles: a gasoline passenger car, a diesel van, a motorbike and a two-stroke scooter. PMID:17874081

Adam, Thomas; Zimmermann, Ralf

2007-11-01

89

A recyclable catalyst for asymmetric transfer hydrogenation with a formic acid-triethylamine mixture in ionic liquid.  

PubMed

A novel task-specific ionic ligand with an imidazolium salt moiety was synthesized, and its catalytic ability and recyclability for asymmetric transfer hydrogenation of acetophenone derivatives with a formic acid-triethylamine azeotropic mixture in an ionic liquid [bmim][PF6] was examined. PMID:15846424

Kawasaki, Ikuo; Tsunoda, Kazuya; Tsuji, Tomoko; Yamaguchi, Tomoko; Shibuta, Hiroki; Uchida, Nozomi; Yamashita, Masayuki; Ohta, Shunsaku

2005-04-28

90

Sorption of phenol on cellulose from binary aqueous-organic mixtures  

Microsoft Academic Search

Sorption of phenol on cellulose from water-dimethyl sulfoxide and water-acetonitrile mixtures was studied. Different shape\\u000a of the isotherms of phenol sorption form these mixtures is due to different character of phenol solvation in different concentration\\u000a regions of water-dimethyl sulfoxide and water-acetonitrile mixtures.

M. I. Voronova; D. A. Kuznetsov; A. G. Zakharov

2008-01-01

91

Biofiltration of a mixture of volatile organic compounds on granular activated carbon.  

PubMed

The performance of a biofilter packed with Active Carbon (AC) was evaluated. The effluent (alcohol, ketones, esters, aromatic and chlorinated compounds) treated was a representative mixture of most common industrial emissions. To achieve a better knowledge of multicomponent adsorption mechanisms, and to underline the interest of inoculating AC, a control abiotic humidified filter had been operated in the same conditions as the biofilter. For a load of 110 g VOC m(-3) AC h(-1), after 55 days of operation, the removal efficiency was higher in the biotic than in the abiotic filter (85% vs 55%, respectively). Moreover, in the biofilter, at steady state, the elimination of all compounds was almost complete except for chlorinated compounds and p-xylene (removal efficiency of 25% and 64%, respectively). The microbial colonization of AC involved a decrease of the adsorption sites accessibility and enhanced the treatment of VOCs (volatile organic compounds) having a lower affinity for activated carbon. Moreover, while aromatic compounds and MIBK were eliminated along the overall height of the biofilter, pollutants with reduced affinity for AC, such as methanol, acetone, and halogenated compounds were only treated on the second half of the reactor. Thus, the affinity for activated carbon was an important parameter controlling the biodegradation process. Nevertheless, the use of AC as packing material in biofilters treating complex mixtures of VOCs is limited. Actually, similar removal efficiency could be reached, in the same conditions, for a biofilter packed with granular peat. Furthermore, for the biofilter packed with AC, the column height necessary to remove biodegradable compounds, with reduced affinity for the support, was important. PMID:12800142

Aizpuru, A; Malhautier, L; Roux, J C; Fanlo, J L

2003-08-20

92

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

Microsoft Academic Search

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

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

2009-01-01

93

A tube-in-tube water\\/zeotropic mixture condenser: design procedure against experimental data  

Microsoft Academic Search

The object of the present paper is related to the design of condensers for the non-azeotropic mixtures of refrigerants. The high temperature glide mixture R-125\\/236ea at three different compositions (0.30\\/0.70, 0.46\\/0.54, 0.64\\/0.36 by mass) was tested during condensation inside a 2 m long smooth horizontal tube-in-tube exchanger. The superheated vapour entering the tube is first cooled and then condensed against

A. Cavallini; G. Censi; D. Del Col; L. Doretti; G. A. Longo; L. Rossetto

2002-01-01

94

Simultaneous determination of mixtures of organic acids or bases based on the differences in the titration spectra  

Microsoft Academic Search

Based on the differences in titration spectra, mixtures of organic acids with similar pKa were determined simultaneously. Principal component regression calibration was used for the evaluation of titration spectra. The effects of differences in pKa and sampling interval of pH on accuracy were studied in detail. Combining precipitation and the acid–base reaction of organic acid, precipitation–acid–base titrimetry is proposed. The

Zhongliang Zhu; Tonghua Li; Peisheng Cong; Zifeng Deng

1999-01-01

95

COMPARISON OF SORPTION ENERGTICS FOR HYDROPHOBIC ORGANIC CHEMICALS BY SYNTHETIC AND NATURAL SORBENTS FROM METHANOL/WATER SOLVENT MIXTURES  

EPA Science Inventory

Reversed-phase liquid chromatography (RPLC) was used to investigate the thermodynamics and mechanisms of hydrophobic organic chemical (HOC) retention from methanol/water solvent mixtures. The enthalpy-entropy compensation model was used to infer that the hydro- phobic sorptive me...

96

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

EPA Science Inventory

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

97

COMPARISON OF SORPTION ENERGETICS FOR HYDROPHOBIC ORGANIC CHEMICALS BY SYNTHETIC AND NATURAL SORBENTS FROM METHANOL/WATER SOLVENT MIXTURES  

EPA Science Inventory

Reversed-phase liquid chromatography (RPLC) was used to investigate the thermodynamics and mechanisms of hydrophobic organic chemical (HOC) retention from methanol/water solvent mixtures. he enthalpy-entropy compensation model was used to infer that the hydrophobic sorptive mecha...

98

Pervaporative dehydration characteristics of an ethanol/water azeotrope through various chitosan membranes.  

PubMed

The permeation and separation characteristics of an ethanol/water azeotrope through chitosan membranes of different molecular weights and degrees of deacetylation during pervaporation were investigated. The normalized permeation rate decreased with increasing molecular weight up to 90 kDa, but at over 90 kDa, the rate increased. On the other hand, the water/ethanol selectivity increased with increasing molecular weight up to 90 kDa but decreased at over 90 kDa. With increasing degree of deacetylation, the water/ethanol permselectivity increased significantly, but the normalized permeation rate decreased. The characteristics of chitosan membranes are discussed based on their chemical and physical structures such as the contact angle, density, degree of swelling, and glass transition temperature. PMID:25662680

Uragami, Tadashi; Saito, Tomoyuki; Miyata, Takashi

2015-04-20

99

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

PubMed

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

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

2014-05-01

100

The Method for Investigating the Structurization of Water-Organic Mixtures  

NASA Astrophysics Data System (ADS)

The investigation of the properties of micellar systems is of great practical importance, since the microheterogeneous structure, in particular, of aqueous-organic solutions can be used to create reaction centers with designed properties, which will make it possible to increase the efficiency of processes associated with the intramolecular conversion of the electronic excitation energy of a molecule. In the present paper, model systems to stimulate chemical reactions are the spatial-temporal structures (STS) formed as a result of photophysical and photochemical reactions, whose time characteristics are highly sensitive to a change in the solvent compositions. The STS evolution processes are slow and the structures formed have macroscopic sizes, which makes the system under consideration a convenient object for experimental studies. The spectral and time characteristics of the spatial-temporal structures luminescing when exposed to UV radiation in aqueous alcohol solutions of anthraquinone are investigated experimentally depending on the volume content of alcohol in a mixture. It is shown that the microheterogeneous structure of aqueous alcohol solutions considerably influences the behavior of the dissipative structures formed.

Karitskaya, S.

2013-12-01

101

Condensation of Non-Azeotropic Refrigerant Blends of R114 and R113 in a Horizontal Annulus with an Enhanced Inner Tube  

NASA Astrophysics Data System (ADS)

Experiments were performed to study the flow characteristics and heat transfer during condensation of non-azeotropic refrigerant blends (NARBs) of R114 and R113 in the annulus of a horizontal double tube. The inner tube was a 19.1mm o.d. corrugated tube with soldered wire fins on the outer surface. The outer tube was a 29.9mm i.d. smooth tube. Experiments were performed at two vapor mass fractions of R114 at the test section inlet of 0.23 and 0.36. The mass velocity of the test fluids ranged from 50 to 200kg/m2·s. The frictional pressure gradient data were correlated fairly well by an empirical equation for condensation of pure R11 and R113 reported in a previous paper. The double tube showed a significant heat transfer enhancement over a smooth tube value. The heat transfer coefficient for NARBs was considerably smaller than that for pure R113. The decrease was more significant for a low mass velocity. A dimensionless correlation for the vapor phase mass transfer coefficient was derived, where the dimensionless parameters for forced convection condensation from a vapor-gas mixture flowing normal to a cylinder was extended to the case of NARBs.

Nozu, Shigeru; Honda, Hiroshi; Aoyama, Tohru; Shibukuwa, Ken-Ichi

102

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

EPA Science Inventory

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

103

Transmission geometry laser desorption atmospheric pressure photochemical ionization mass spectrometry for analysis of complex organic mixtures.  

PubMed

We present laser desorption atmospheric pressure photochemical ionization mass spectrometry (LD/APPCI MS) for rapid throughput analysis of complex organic mixtures, without the need for matrix, electric discharge, secondary electrospray, or solvents/vaporizers. Analytes dried on a microscope slide are vaporized in transmission geometry by a laser beam aligned with the atmospheric pressure inlet of the mass spectrometer. The laser beam initiates a cascade of reactions in the region between the glass slide and MS inlet, leading to generation of reagent ions for chemical ionization of vaporized analyte. Positive analyte ions are generated predominantly by proton transfer, charge exchange, and hydride abstraction, whereas negative ions are generated by electron capture or proton transfer reactions, enabling simultaneous analysis of saturated, unsaturated, and heteroatom-containing hydrocarbons. The absence of matrix interference renders LD/APPCI MS particularly useful for analysis of small molecules (<2000 Da) such as those present in petroleum crude oil and petroleum deposits. [M + H](+) and M(+•) dominate the positive-ion mass spectra for olefins and polyaromatic hydrocarbons, whereas saturated hydrocarbons are observed mainly as [M - H](+) and/or M(+•). Heteroatom-containing hydrocarbons are observed predominantly as [M + H](+). [M - H](-) and M(-•) are the dominant negative ions observed for analytes of lower gas-phase basicity or higher electron affinity than O2. The source was coupled with a 9.4 T Fourier transform ion cyclotron resonance mass spectrometer (FTICR MS) to resolve and identify thousands of peaks from Athabasca bitumen heavy vacuum gas oil distillates (400-425 and 500-538 °C), enabling simultaneous characterization of their polar and nonpolar composition. We also applied LD/APPCI FTICR MS for rapid analysis of sodium and calcium naphthenate deposits with little to no sample pretreatment to provide mass spectral fingerprints that enable reliable compositional characterization. PMID:25347814

Nyadong, Leonard; Mapolelo, Mmilili M; Hendrickson, Christopher L; Rodgers, Ryan P; Marshall, Alan G

2014-11-18

104

Soil surface colonization by phototrophic indigenous organisms, in two contrasted soils treated by formulated maize herbicide mixtures.  

PubMed

Soil phototrophic microorganisms, contributors to soil health and food webs, share their particular metabolism with plants. Current agricultural practices employ mixtures of pesticides to ensure the crops yields and can potentially impair these non-target organisms. However despite this environmental reality, studies dealing the susceptibility of phototrophic microorganisms to pesticide mixtures are scarce. We designed a 3 months microcosm study to assess the ecotoxicity of realistic herbicide mixtures of formulated S-metolachlor (Dual Gold Safeneur(®)), mesotrione (Callisto(®)) and nicosulfuron (Milagro(®)) on phototrophic communities of two soils (Limagne vertisol and Versailles luvisol). The soils presented different colonizing communities, with diatoms and chlorophyceae dominating communities in Limagne soil and cyanobacteria and bryophyta communities in Versailles soil. The results highlighted the strong impairment of Dual Gold Safeneur(®) treated microcosms on the biomass and the composition of both soil phototrophic communities, with no resilience after a delay of 3 months. This study also excluded any significant mixture effect on these organisms for Callisto(®) and Milagro(®) herbicides. We strongly recommend carrying on extensive soil studies on S-metolachlor and its commercial formulations, in order to reconsider its use from an ecotoxicological point of view. PMID:25129149

Joly, Pierre; Misson, Benjamin; Perrière, Fanny; Bonnemoy, Frédérique; Joly, Muriel; Donnadieu-Bernard, Florence; Aguer, Jean-Pierre; Bohatier, Jacques; Mallet, Clarisse

2014-11-01

105

Real-Time Synthesis of 3D Animations by Learning Parametric Gaussians Using Self-Organizing Mixture Networks  

Microsoft Academic Search

In this paper, we present a novel real-time approach to synthesizing 3D character animations of required style by adjusting\\u000a a few parameters or scratching mouse cursor. Our approach regards learning captured 3D human motions as parametric Gaussians\\u000a by the self-organizing mixture network (SOMN). The learned model describes motions under the control of a vector variable\\u000a called the style variable, and

Yi Wang; Hujun Yin; Li-zhu Zhou; Zhi-qiang Liu

2006-01-01

106

Esterification activity and conformation studies of Burkholderia cepacia lipase in conventional organic solvents, ionic liquids and their co-solvent mixture media  

Microsoft Academic Search

In this work, experiments were carried out to evaluate the esterification activity and conformation of lipase from Burkholderia cepacia in the selected conventional organic solvents, ionic liquids and their co-solvent mixture media. The results revealed that the activity of esterification of B. cepacia lipase was mostly highest in co-solvent mixture of ionic liquids–organic solvents, followed by conventional organic solvents and

Shaotao Pan; Xue Liu; Yadong Xie; Yuyin Yi; Chong Li; Yunjun Yan; Yun Liu

2010-01-01

107

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

SciTech Connect

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

Charles J Werth; Albert J Valocchi, Hongkyu Yoon

2011-05-21

108

Screening Metal-Organic Frameworks by Analysis of Transient Breakthrough of Gas Mixtures in a Fixed Bed Adsorber  

SciTech Connect

Metal–organic frameworks (MOFs) offer considerable potential for separating a variety of mixtures that are important in applications such as CO? capture and H? purification. In view of the vast number of MOFs that have been synthesized, there is a need for a reliable procedure for comparing screening and ranking MOFs with regard to their anticipated performance in pressure swing adsorption (PSA) units. For this purpose, the most commonly used metrics are the adsorption selectivity and the working capacity. Here, we suggest an additional metric for comparing MOFs that is based on the analysis of the transient response of an adsorber to a step input of a gaseous mixture. For a chosen purity of the gaseous mixture exiting from the adsorber, a dimensionless breakthrough time ?{sub break} can be defined and determined; this metric determines the frequency of required regeneration and influences the productivity of a PSA unit. The values of ?{sub break} are dictated both by selectivity and by capacity metrics .By performing transient adsorber calculations for separation of CO?/H?, CO?/CH?, CH?/H?, and CO?/CH?/H? mixtures, we compare the values of ?break to highlight some important advantages of MOFs over conventionally used adsorbents such as zeolite NaX. For a given separation duty, such comparisons provide a more realistic ranking of MOFs than afforded by either selectivity or capacity metrics alone. We conclude that breakthrough calculations can provide an essential tool for screening MOFs.

Krishna, Rajamani [Van‘t Hoff Inst. for Molecular Sciences, Univ. of Amsterdam (Netherlands); Long, Jeffrey R. [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)

2011-07-07

109

Measurement of the Soret coefficients in organic/water mixtures by thermal lens spectrometry  

NASA Astrophysics Data System (ADS)

In this work we utilize an alternative optical method based on thermal lens spectroscopy for characterizing the thermal diffusion in binary liquid mixtures. In this method, the thermal lens and the Soret signals are separated by a time interval to determine the Soret coefficients. As a demonstrative experiment, the Soret coefficients of isopropanol/water and acetone/water mixtures have been measured using that variant. Our results were compared with the recently published experimental and theoretical calculations and very good agreement was achieved.

Cabrera, Humberto; Cordido, Flaminio; Velásquez, Ana; Moreno, Pablo; Sira, Eloy; López-Rivera, Santos A.

2013-04-01

110

Separation of dilute organic\\/water mixtures with asymmetric poly(vinylidene fluoride) membranes  

Microsoft Academic Search

An in-depth investigation of integral asymmetric poly(vinylidene fluoride) (PVDF) membranes has been carried out for the extraction of polar and non-polar organic compounds from dilute organic-in-water feed solutions. Membrane performance for low and high-boiling non-polar organic feed components was excellent, with separation factors as high as 4900 and high organic transmembrane fluxes. Polar organic feed components such as ethanol and

K. Jian; P. N. Pintauro; R. Ponangi

1996-01-01

111

Neurological and neurophysiological examinations of workers occupationally exposed to organic solvent mixtures used in the paint and varnish production.  

PubMed

The aim of this work was to examine the nervous system of workers chronically exposed to mixtures of organic solvent at concentrations within or slightly exceeding the MAC values, used in the manufacture of paints and lacquers. The tests were performed on a group of 175 people, 107 men aged 22-59 (x = 41.25), and 68 women aged 20-55 (x = 38.62). The period of employment was x = 17.34 years and cumulative dose index 16.97 for males; for females, the corresponding values were x = 14.75 and x = 11.42, respectively. The control group included 175 people (107 men and 68 women) not exposed to chemicals matched according to sex, age, and work shift distribution. The neurological examinations included subjective and objective examinations of the nervous system, electroencephalographic (EEG) and visual evoked potential (VEP) evaluations. The assessment of organic solvent exposure was performed according to the method described in PN89/Z-04008/07, and the solvent mixtures were shown to contain xylenes, ethyltoluenes, trimethylbenzenes, propylbenzene, ethylbenzene, toluene, aliphatic hydrocarbons and the components of painter's naphtha. The most frequent complaints among the exposed males included headache, vertigo, concentration difficulties, sleep disorders, sleepiness during the day, increased emotional irritability, mood swings with a tendency to anxiety. The objective neurological examinations did not reveal organic lesions in the central or peripheral nervous systems. Generalised and paroxysmal changes were most common recordings in the abnormal EEG. VEP examinations revealed abnormalities, primarily in the latency of the response evoked. The results of this study suggest that exposures to concentrations within MAC values, or below 1.5 of the MAC values of organic solvents mixtures used in the manufacture of paints and lacquers produce subclinical health effect in the nervous system. PMID:8972166

Indulski, J A; Si?czuk-Walczak, H; Szymczak, M; Weso?owski, W

1996-01-01

112

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

EPA Science Inventory

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

113

Binary Mixtures of Permanganate and Chlorinated Volatile Organic Compounds in Groundwater Samples: Sample Preservation and Analysis  

EPA Science Inventory

Ground water samples collected at sites where in-situ chemical oxidation (ISCO) has been deployed may contain binary mixtures of ground water contaminants and permanganate (MnO4-), an oxidant injected into the subsurface to destroy the contaminant. Commingling of the oxidant and ...

114

Antagonistic interactions of an arsenic-containing mixture in a multiple organ carcinogenicity bioassay  

Microsoft Academic Search

Inorganic arsenic (As), 1,2-dichloroethane (DCE), vinyl chloride (VC) and trichloroethylene (TCE) are frequently identified as groundwater contaminants near hazardous waste disposal sites. While the carcinogenicity of each of these chemicals has been extensively studied individually, little information exists regarding their carcinogenic potential in combination. Therefore, we investigated the carcinogenic promoting potential of chemical mixtures containing arsenic, DCE, VC and TCE

Wendy A Pott; Stephen A Benjamin; Raymond S. H Yang

1998-01-01

115

The influence of cellulose complexite swelling on its protolytic properties in aqueous-organic mixtures  

NASA Astrophysics Data System (ADS)

The swellability of cellulose complexite containing hydroxamic acid and amidoxime groups and its matrix (grafted copolymer of cellulose and polyacrylonitrle) in variable-composition water-methanol and water-dimethylsulfoxide mixtures was studied by pH metry, refractometry, and atomic absorption spectroscopy over the pH range 5.30 12.87 corresponding to the dissociation of the functional groups of fibers. The solvation characteristics of fibers, including specific volume, degree of sorption, and interphase distribution coefficients of mixture components, were determined experimentally. The Gibbs energies of sample swelling and the dissociation constants of complexite groups were calculated taking into account the contribution of the solvation parameter. The suggestion was made that the acid properties of the polymer were determined by the predominant influence of the specific solvation of its matrix caused by the formation of H-bonds in complexite-solvent systems.

Miroshnik, L. V.; Korovnikova, N. I.; Aleksandrov, A. V.; Dubyna, A. M.

2008-09-01

116

Benchmark values for the Soret, thermal diffusion and diffusion coefficients of three binary organic liquid mixtures  

Microsoft Academic Search

With the aim of providing reliable benchmark values, we have measured the Soret, diffusion and thermal diffusion coefficients of the three binary mixtures of dodecane, isobutylbenzene and 1,2,3,4 tetrahydronaphthalene for a concentration of 50 wt% at a temperature of 25°C. The experimental techniques applied by the five participating laboratories are transient holographic gratings, annular and parallelepipedic thermogravitational columns, and vertical

J. K. Platten; M. M. Bou-Ali; P. Costesèque; J. F. Dutrieux; W. Köhler; C. Leppla; S. Wiegand; G. Wittko

2003-01-01

117

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

PubMed

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

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

2015-04-01

118

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

E-print Network

THE EFFECT OF HUMIDITY ON THE COLLECTION EFFICIENCIES OF TWO MONITORING METHODS WHEN EXPOSED TO A MIXTURE OF ORGANIC SOLVENTS A Thesis by LORI ANN RUSHLOW Submitted to the Office of Graduate Studies of Texas A&M University in partial... by LORI ANN RUSHLOW Approved as to style and content by: zc ar B. Ko e (Chair of Committ e) ohn P. Wagn (Member) K. Bennett (Head of Department) oy W. Han Jr. (Member) August 1989 ABSTRACT The Effect of Humidity on the Collection Efficiencies...

Rushlow, Lori Ann

1989-01-01

119

Evaporation-free inverted organic photovoltaics using a mixture of silver nanoparticle ink formulations for solution-processed top electrodes  

NASA Astrophysics Data System (ADS)

We report an investigation of inkjet-printed silver (Ag) nanoparticle inks combined with a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) formulation for solution-processed top electrodes in inverted organic photovoltaics (OPVs) employing the poly(3-hexylthiopehene):phenyl-C61-butyric acid methyl ester material system. We propose a suitable mixture of Ag nanoparticle inks to control the printability and electrical conductivity of the solution-processed top electrode. Based on the proposed solution-processed hole-selective contact, a power conversion efficiency in the range of 3% is reported for evaporation-free inverted OPVs.

Georgiou, Efthymios; Savva, Achilleas; Neophytou, Marios; Hermerschmidt, Felix; Demosthenous, Tasos; Choulis, Stelios A.

2014-12-01

120

Role of solvent selectivity in the equilibrium surface composition of monolayers formed from a solution containing mixtures of organic thiols.  

PubMed

We have developed a simple model to quantify the effect of solvent selectivity on the surface composition of two-component self-assembled monolayers formed from solutions containing mixtures of organic thiols. The coarse-grained molecular model incorporates the relevant intermolecular interactions in the solution and monolayer to yield an expression for the free energy of monolayer formation. Minimization of the free energy results in a simple and analytically tractable expression for the monolayer composition as a function of solvent selectivity (defined as the difference in the Flory-type interaction parameters of the two organic thiols in the solution) and the degree of incompatibility between the adsorbate molecules. A comparison of our theory to experiments on the formation of two-component self-assembled monolayers from solution indicates that the coarse-grained molecular model captures the trends in the experimental data quite well. PMID:20565086

Oyerokun, Folusho T; Vaia, Richard A; Maguire, John F; Farmer, Barry L

2010-07-20

121

Kinetic determination of organic vapor mixtures with single piezoelectric quartz crystal sensor using artificial neural networks.  

PubMed

A single piezoelectric quartz crystal coated with one kind of crown ether was applied to the simultaneous determination of binary acid and amine vapor mixtures. From the adsorption and desorption curves of analytes, which were somewhat different in shape, frequency shifts from ten time windows were taken as inputs for artificial neural networks (ANN). Prediction results were satisfactory for ANN in both sample sets. The average relative errors, for formic acid and acrylic acid were 5%, for n-butylamine and aniline, they were 3% with ANN respectively. The effects of number of neurons in the hidden layer of ANN on the performance of the network are also discussed. PMID:18966826

Xing, W L; He, X W

1997-06-01

122

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

123

Photonic Crystal Based Sensor for Organic Solvents and for Solvent-Water Mixtures  

PubMed Central

Monodisperse polystyrene nanoparticles with a diameter of 173 nm were incorporated into a polydimethylsiloxane matrix where they display an iridescent color that can be attributed to the photonic crystal effect. The film is of violet color if placed in plain water, but turns to red in the presence of the non-polar solvent n-hexane. Several solvents were studied in some detail. We show that such films are capable of monitoring the water content of ethanol/water mixtures, where only 1% (v/v) of water leads to a shift of the peak wavelength of reflected light by 5 nm. The method also can be applied to determine, both visually and instrumentally, the fraction of methanol in ethanol/methanol mixtures. Here, a fraction of 1% of methanol (v/v) results in a wavelength shift of 2 nm. The reflected wavelength is not influenced by temperature changes nor impeded by photobleaching. The signal changes are fully reversible and response times are <1 s. PMID:23235441

Fenzl, Christoph; Hirsch, Thomas; Wolfbeis, Otto S.

2012-01-01

124

EXPOSURE OF HUMANS TO A VOLATILE ORGANIC MIXTURE: I. BEHAVIORAL ASSESSMENT  

EPA Science Inventory

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

125

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

DOEpatents

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

Pekala, Richard W. (Pleasant Hill, CA)

1996-01-01

126

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

DOEpatents

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

Pekala, Richard W. (Pleasant Hill, CA)

1995-01-01

127

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

DOEpatents

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

Pekala, Richard W. (Pleasant Hill, CA)

1998-04-28

128

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

DOEpatents

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

Pekala, R.W.

1996-09-17

129

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

DOEpatents

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

Pekala, R.W.

1998-04-28

130

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

DOEpatents

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

Pekala, R.W.

1995-12-19

131

Testing secondary organic aerosol models using smog chamber data for complex precursor mixtures: influence of precursor volatility and molecular structure  

NASA Astrophysics Data System (ADS)

We use secondary organic aerosol (SOA) production data from an ensemble of unburned fuels measured in a smog chamber to test various SOA formation models. The evaluation considered data from 11 different fuels including gasoline, multiple diesels, and various jet fuels. The fuels are complex mixtures of species; they span a wide range of volatility and molecular structure to provide a challenging test for the SOA models. We evaluated three different versions of the SOA model used in the Community Multiscale Air Quality (CMAQ) model. The simplest and most widely used version of that model only accounts for the volatile species (species with less than or equal to 12 carbons) in the fuels. It had very little skill in predicting the observed SOA formation (R2 = 0.04, fractional error = 108%). Incorporating all of the lower-volatility fuel species (species with more than 12 carbons) into the standard CMAQ SOA model did not improve model performance significantly. Both versions of the CMAQ SOA model over-predicted SOA formation from a synthetic jet fuel and under-predicted SOA formation from diesels because of an overly simplistic representation of the SOA formation from alkanes that did not account for the effects of molecular size and structure. An extended version of the CMAQ SOA model that accounted for all organics and the influence of molecular size and structure of alkanes reproduced the experimental data. This underscores the importance of accounting for all low-volatility organics and information on alkane molecular size and structure in SOA models. We also investigated fitting an SOA model based solely on the volatility of the precursor mixture to the experimental data. This model could describe the observed SOA formation with relatively few free parameters, demonstrating the importance of precursor volatility for SOA formation. The exceptions were exotic fuels such as synthetic jet fuel that expose the central assumption of the volatility-dependent model that most emissions consist of complex mixtures with similar distribution of molecular classes. Despite its shortcomings, SOA formation as a function of volatility may be sufficient for modeling SOA formation in chemical transport models.

Jathar, S. H.; Donahue, N. M.; Adams, P. J.; Robinson, A. L.

2014-06-01

132

KINETICS AND SELECTIVITY OF DEEP CATALYTIC OXIDATION OF VOLATILE ORGANIC COMPOUND MIXTURES  

EPA Science Inventory

The paper gives results of a fundamental study of low-temperature deep (complete) oxidation of n-hexane, benzene, and ethyl-acetate over a 0.1% Pt, 3% Ni/gamma-AL203 catalyst. (NOTE: Deep catalytic combustion of volatile organic compounds--VOCs--is emerging as an important emissi...

133

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

EPA Science Inventory

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

134

SOLUBILITY OF ORGANIC BIOCIDES IN SUPERCRITICAL CO2 AND CO2+ COSOLVENT MIXTURES  

EPA Science Inventory

Solubilities of four organic biocides in supercritical carbon dioxide (Sc-CO2) were measured using a dynamic flowr apparatus over a pressure range of 10 to 30 MPa and temperature of 35-80 degrees C. The biocides studied were: Amical-48 (diiodomethyl p-tolyl sulfone), chlorothalo...

135

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

NASA Astrophysics Data System (ADS)

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

Francisca, Franco M.; Montoro, Marcos A.

2012-05-01

136

Thermodynamic functions, freezing transition, and phase diagram of dense carbon-oxygen mixtures in white dwarfs  

SciTech Connect

Equations of state for dense carbon-oxygen (C-O) binary-ionic mixtures (BIM's) appropriate to the interiors of white dwarfs are investigated through Monte Carlo simulations, by solution of relevant integral equations andvariational calculations in the density-functional formalism. It is thereby shown that the internal energies of the C-O BIM solids and fluids both obey precisely the linear mixing formulas. We then present an accurate calculation of the phase diagram associated with freezing transitions in such BIM materials, resulting in a novel prediction of an azeotropic diagram. Discontinuities of the mass density across the azeotropic phase boundaries areevaluated numerically for application to a study of white-dwarf evolution.

Iyetomi, H.; Ogata, S.; Ichimaru, S.

1989-07-01

137

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

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

138

Simulation of nonazeotropic refrigerant mixtures for use in a dual-circuit refrigerator\\/freezer with countercurrent heat exchanges  

Microsoft Academic Search

The paper discusses the simulation of Non-azeotropic Refrigerant Mixtures (NARMs) for use in a dual-circuit refrigerator\\/freezer (RF) with countercurrent heat exchangers. The simulated RF has two complete and independent refrigeration cycles for its two compartments. It uses a NARM in each cycle and countercurrent heat exchangers throughout. In a standard cabinet, the RF is simulated to provide energy savings of

J. C. Bare; C. L. Gage; R. Radermacher; D. S. Jung

1992-01-01

139

Simulation of nonazeotropic refrigerant mixtures for use in a dual-circuit refrigerator\\/freezer with countercurrent heat exchangers  

Microsoft Academic Search

The paper discusses a refrigerator\\/freezer (RF) system that has two complete and independent refrigeration cycles for the two compartments. It uses a non-azeotropic refrigerant mixture (NARM) in each cycle and countercurrent heat exchangers throughout. In a standard cabinet, this RF appears to provide energy savings of 24%, compared to current U.S. RF designs. The NARMs modeled with the best performance

J. C. Bare; C. L. Gage; R. Radermacher; D. Jung

1991-01-01

140

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

SciTech Connect

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

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

1992-01-01

141

Thermodynamics of Multicomponent PAH Mixtures and Development of Tar-Like Behavior  

PubMed Central

This study explores the solid/liquid phase behavior of mixtures of polycyclic aromatic hydrocarbons (PAHs), exploring the transition from non-ideal solid mixtures to a relatively ideal liquid behavior characteristic of “tars”. PAH mixtures have been studied using differential scanning calorimetry, melting point analysis and Knudsen effusion. Mixtures of anthracene, pyrene and fluoranthene show behavior that is consistent with other binary PAH mixtures; that is, the initially solid mixture exhibits a significant melting point depression, relative to the pure components, and in a certain range of composition, solid azeotrope behavior on vaporization. As the number of distinct PAH species is increased (by adding in benzo[a]pyrene, phenanthrene, fluorene and chrysene) this behavior gradually gives way to liquid phase character at even room temperature, and the vaporization behavior approaches that crudely predictable from ideal mixture theory. PMID:21442010

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

2011-01-01

142

Esterification activity and conformation studies of Burkholderia cepacia lipase in conventional organic solvents, ionic liquids and their co-solvent mixture media.  

PubMed

In this work, experiments were carried out to evaluate the esterification activity and conformation of lipase from Burkholderia cepacia in the selected conventional organic solvents, ionic liquids and their co-solvent mixture media. The results revealed that the activity of esterification of B. cepacia lipase was mostly highest in co-solvent mixture of ionic liquids-organic solvents, followed by conventional organic solvents and ionic liquids. Hence, co-solvent mixture was a high-effective strategy to enhance the activity of B. cepacia lipase for non-aqueous enzymology reaction. Conformational studies via circular dichroism spectroscopy indicated that the secondary structure of B. cepacia lipase was variant in the above-mentioned media, especially the content of alpha-helix, which was probably responsible for lipase activity difference. PMID:20713309

Pan, Shaotao; Liu, Xue; Xie, Yadong; Yi, Yuyin; Li, Chong; Yan, Yunjun; Liu, Yun

2010-12-01

143

Pervaporation of organic\\/water mixtures through B-ZSM-5 zeolite membranes on monolith supports  

Microsoft Academic Search

High-quality, boron-substituted ZSM-5 zeolite membranes were prepared on Al2O3-coated SiC multi-channel monolith supports. Monoliths have larger surface to volume ratios than tubular supports and are more practical for large-scale applications. Two types of supports with 66 channels (2mm×2mm, 10.6cm2surfaceareacm?3) and 22 channels (4mm×4mm, 7.2cm2cm?3) were used. The membranes effectively removed alcohols and acetone from 5wt.% organic\\/water binary feeds by pervaporation

Travis C Bowen; Halil Kalipcilar; John L Falconer; Richard D Noble

2003-01-01

144

Adsorption of aqueous organic mixtures on a chiral stationary phase with bound antibiotic eremomycin.  

PubMed

The adsorption of two typical hydro-organic mobile phases, with methanol and acetonitrile as the organic component, on an antibiotic based chiral stationary phase (CSP) Nautilus-E was studied by the minor perturbation method. In both cases, the excess adsorption of water was positive over a wide range of concentrations from 0 to ?75 or 90 mol% for MeOH or MeCN containing mobile phases, respectively. Such hydrophilic properties of the CSP were attributed to multiple polar functional groups of the chiral ligand and to the residual silanol groups of the silica support. The adsorbed phase was found to be thinner for H?O-MeOH (?1.1?) and thicker for H?O-MeCN (?9.4?). The measurements of the column hold-up volume by different methods allowed us to suggest a model of the adsorbed phase consisting of the volume between bound chiral selectors inaccessible to large size molecules and of the stagnant layer of the mobile phase adsorbed on the external surface of the chiral selectors. PMID:25182859

Nikitina, Yuliya K; Ali, Imran; Asnin, Leonid D

2014-10-10

145

Subsurface interactions of actinide species and microorganisms : implications for the bioremediation of actinide-organic mixtures.  

SciTech Connect

By reviewing how microorganisms interact with actinides in subsurface environments, we assess how bioremediation controls the fate of actinides. Actinides often are co-contaminants with strong organic chelators, chlorinated solvents, and fuel hydrocarbons. Bioremediation can immobilize the actinides, biodegrade the co-contaminants, or both. Actinides at the IV oxidation state are the least soluble, and microorganisms accelerate precipitation by altering the actinide's oxidation state or its speciation. We describe how microorganisms directly oxidize or reduce actinides and how microbiological reactions that biodegrade strong organic chelators, alter the pH, and consume or produce precipitating anions strongly affect actinide speciation and, therefore, mobility. We explain why inhibition caused by chemical or radiolytic toxicities uniquely affects microbial reactions. Due to the complex interactions of the microbiological and chemical phenomena, mathematical modeling is an essential tool for research on and application of bioremediation involving co-contamination with actinides. We describe the development of mathematical models that link microbiological and geochemical reactions. Throughout, we identify the key research needs.

Banaszak, J.E.; Reed, D.T.; Rittmann, B.E.

1999-02-12

146

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

E-print Network

.7�104 Glyoxal in 3.1 M (NH4)2SO4 78.5 0.009 ± 14 -0.012 ± 19 Methylglyoxal 72.5 0.025 ± 3.6�10-3 2.99 ± 1.25 ** Methylglyoxal in 3.1 M (NH4)2SO4 78.5 0.018 ± 8�10-4 140 ± 34 Alanine 72.5 0.014 ± 2.7�10-2 5.99 ± 17.4 Alanine using Eqn. (5). Organic k Acetaldehyde -0.36 ± 0.02 Methylglyoxal -2.34 ± 0.05 Alanine 1.04 ± 0

Meskhidze, Nicholas

147

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

PubMed

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

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

2013-03-15

148

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

149

Evaluation of the effects of a mixture of organic acids and duration of storage on the survival of salmonella on Turkey carcasses.  

PubMed

Samples from turkey carcasses previously inoculated with Salmonella Enteritidis 33/66 were subjected to the effect of various mixtures of equal parts of organic acid solutions (acetic, ascorbic, citric, lactic, and tartaric acids). The first part of the study concerned analysis of the influence of the mixtures of organic acids over 15 or 30 min on Salmonella Enteritidis on turkey carcasses. Turkey breast samples were inoculated with Salmonella Enteritidis at 3.7, 2.7, 1.7, 0.7, and 0.07 log CFU. The antibacterial effectiveness of the organic acids differed depending on the initial population of Salmonella on the turkey carcasses. Salmonella was most sensitive to mixtures of equal parts of 1% ascorbic, 1% citric, and 1% tartaric acids. The second part of the study involved determining the influence the organic acid mixtures had on survival of Salmonella Enteritidis on turkey meat stored at 4°C for 2, 4, or 6 days. The level of Salmonella was determined using a most-probable-number method. Salmonella Enteritidis was inoculated into a nutrient broth, incubated at 37°C for 24 h, and then added to the diluent in which the turkey breast samples were immersed for 5 min. The initial Salmonella level of the control samples of turkey breast following immersion was determined in each analysis. After storage at 4°C, turkey samples were transferred to the organic acid solutions for 15 min. Stainless steel templates were used to swab 50 cm(2) of the turkey breast samples. During storage at 4°C, the Salmonella level in the meat samples decreased. The largest decrease occurred at 4°C after 6 days with equal parts of 1% acetic acid, 1% lactic acid, and 1% tartaric acid. Thus, treatment of raw turkey breasts with a mixture of organic acids is a promising option for reducing the risk of the presence of Salmonella. PMID:25719885

Miko?ajczyk, Anita

2015-03-01

150

Detailed chemical characterization of unresolved complex mixtures in atmospheric organics: Insights into emission sources, atmospheric processing, and secondary organic aerosol formation  

NASA Astrophysics Data System (ADS)

Recent studies suggest that semivolatile organic compounds (SVOCs) are important precursors to secondary organic aerosol (SOA) in urban atmospheres. However, knowledge of the chemical composition of SVOCs is limited by current analytical techniques, which are typically unable to resolve a large number of constitutional isomers. Using a combination of gas chromatography and soft photoionization mass spectrometry, we characterize the unresolved complex mixture (UCM) of semivolatile aliphatic hydrocarbons observed in Pasadena, California (~16 km NE of downtown Los Angeles), and Bakersfield, California, during the California Research at the Nexus of Air Quality and Climate Change 2010. To the authors' knowledge, this work represents the most detailed characterization of the UCM in atmospheric samples to date. Knowledge of molecular structures, including carbon number, alkyl branching, and number of rings, provides important constraints on the rate of atmospheric processing, as the relative amounts of branched and linear alkanes are shown to be a function of integrated exposure to hydroxyl radicals. Emissions of semivolatile branched alkanes from fossil fuel-related sources are up to an order of magnitude higher than those of linear alkanes, and the gas-phase OH rate constants of branched alkanes are ~30% higher than their linear isomers. Based on a box model considering gas/particle partitioning, emissions, and reaction rates, semivolatile branched alkanes are expected to play a more important role than linear alkanes in the photooxidation of the UCM and subsequent transformations into SOA. Detailed speciation of semivolatile compounds therefore provides essential understanding of SOA sources and formation processes in urban areas.

Chan, Arthur W. H.; Isaacman, Gabriel; Wilson, Kevin R.; Worton, David R.; Ruehl, Christopher R.; Nah, Theodora; Gentner, Drew R.; Dallmann, Timothy R.; Kirchstetter, Thomas W.; Harley, Robert A.; Gilman, Jessica B.; Kuster, William C.; Gouw, Joost A.; Offenberg, John H.; Kleindienst, Tadeusz E.; Lin, Ying H.; Rubitschun, Caitlin L.; Surratt, Jason D.; Hayes, Patrick L.; Jimenez, Jose L.; Goldstein, Allen H.

2013-06-01

151

Impact of aerosol liquid water on secondary organic aerosol yields of irradiated toluene\\/propylene\\/NO x \\/(NH 4) 2SO 4\\/air mixtures  

Microsoft Academic Search

Laboratory experiments were conducted to assess whether the presence of liquid water on pre-existing submicron ammonium sulfate aerosols affects yields of condensible organic compounds. Toluene\\/propylene\\/NOx\\/air mixtures were irradiated in the presence of submicron ammonium sulfate aerosol for a series of relative humidities and ammonium sulfate concentrations, generating aerosols containing organic and inorganic constituents with liquid water concentrations ranging from 4

E. O. Edney; D. J. Driscoll; R. E. Speer; W. S. Weathers; T. E. Kleindienst; W. Li; D. F. Smith

2000-01-01

152

Hydrophobic treatment of organics against glass employing nonequilibrium atmospheric pressure pulsed plasmas with a mixture of CF4 and N2 gases  

Microsoft Academic Search

A hydrophobic organics surface selectively against glass was realized by employing nonequilibrium atmospheric-pressure pulsed plasmas with a mixture of CF4 and N2 gases. The organic surface was drastically altered to have a high hydrophobicity, while the glass surface itself remained hydrophilic after the plasma treatment with the addition of a small amount of CF4 to the N2 gas. After 100

Hirotoshi Inui; Keigo Takeda; Kenji Ishikawa; Takuya Yara; Tsuyoshi Uehara; Makoto Sekine; Masaru Hori

2011-01-01

153

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

Microsoft Academic Search

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

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

2001-01-01

154

Entropic separations of mixtures of aromatics by selective face-to-face molecular stacking in one-dimensional channels of metal-organic frameworks and zeolites.  

PubMed

Separation of challenging mixtures using metal-organic frameworks can be achieved by an entropy-driven mechanism, where one of the components can arrange into a "face-to-face" stacking, thus reducing its "footprint" and reaching a higher saturation loading. PMID:25504615

Torres-Knoop, Ariana; Balestra, Salvador R G; Krishna, Rajamani; Calero, Sofía; Dubbeldam, David

2015-02-23

155

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

NASA Astrophysics Data System (ADS)

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

Sanchez, Tim

156

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

SciTech Connect

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

Usula, M.; Marincola, F. Cesare; Porcedda, S. [Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Cagliari, S.S. 554 Bivio Sestu, 09042 Monserrato (Italy)] [Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Cagliari, S.S. 554 Bivio Sestu, 09042 Monserrato (Italy); Mocci, F., E-mail: fmocci@unica.it [Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Cagliari, S.S. 554 Bivio Sestu, 09042 Monserrato (Italy); Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm (Sweden); Gontrani, L., E-mail: lorenzo.gontrani@gmail.com [CNR – Istituto di Struttura della Materia, Area della Ricerca di Roma Tor Vergata, Via del Fosso del Cavaliere 100, I-00133 Roma (Italy); Dipartimento di Chimica, Università di Roma “La Sapienza,” P.le Aldo Moro 5, I-00185 Roma (Italy); Caminiti, R. [Dipartimento di Chimica, Università di Roma “La Sapienza,” P.le Aldo Moro 5, I-00185 Roma (Italy)] [Dipartimento di Chimica, Università di Roma “La Sapienza,” P.le Aldo Moro 5, I-00185 Roma (Italy)

2014-03-28

157

Factors associated with sources, transport, and fate of volatile organic compounds and their mixtures in aquifers of the United States  

USGS Publications Warehouse

Factors associated with sources, transport, and fate of volatile organic compounds (VOCs) in groundwater from aquifers throughout the United States were evaluated using statistical methods. Samples were collected from 1631 wells throughout the conterminous United States between 1996 and 2002 as part of the National Water-Quality Assessment (NAWQA) Program of the U.S. Geological Survey. Water samples from wells completed in aquifers used to supply drinking water were analyzed for more than 50 VOCs. Wells were primarily rural domestic water supplies (1184), followed by public water supplies (216); the remaining wells (231) supplied a variety of uses. The median well depth was 50 meters. Age-date information shows that about 60% of the samples had a fraction of water recharged after 1953. Chloroform, toluene, 1,2,4-trimethylbenzene, and perchloroethene were some of the frequently detected VOCs. Concentrations generally were less than 1 ??g/L. Source factors include, in order of importance, general land-use activity, septic/sewer density, and sites where large concentrations of VOCs are potentially released, such as leaking underground storage tanks. About 10% of all samples had VOC mixtures that were associated with concentrated sources; 20% were associated with dispersed sources. Important transport factors included well/screen depth, precipitation/groundwater recharge, air temperature, and various soil characteristics. Dissolved oxygen was strongly associated with VOCs and represents the fate of many VOCs in groundwater. Well type (domestic or public water supply) was also an important explanatory factor. Results of multiple analyses show the importance of (1) accounting for both dispersed and concentrated sources of VOCs, (2) measuring dissolved oxygen when sampling wells to help explain the fate of VOCs, and (3) limiting the type of wells sampled in monitoring networks to avoid unnecessary variance in the data, or controlling for this variance during data analysis.

Squillace, P.J.; Moran, M.J.

2007-01-01

158

The use of growth and behavioral endpoints to assess the effects of pesticide mixtures upon aquatic organisms.  

PubMed

Aquatic communities are often subject to complex contaminant mixtures, usually at sublethal concentrations, that can cause long-term detrimental effects. Chemicals within mixtures can effectively interact, resulting in synergism, antagonism or additivity. We investigated the tertiary mixture effects of two pyrethroids, lambda-cyhalothrin and permethrin, and the organophosphate chlorpyrifos, evaluating sublethal endpoints; immobility and growth, on Chironomus dilutus in 10-day exposures. We utilized a toxic units (TU) approach, based on median lethal concentrations (LC50) for each compound. The concepts of independent action and concentration addition were used to compare predicted mixture toxicity to observed mixture toxicity. Increased immobility resulted from mixture concentrations ?1 TU (7.45 ng/L lambda-cyhalothrin × 24.90 ng/L permethrin × 129.70 ng/L chlorpyrifos), and single pesticides concentrations ?0.25 TU (5.50 ng/L lambda-cyhalothrin, 24.23 ng/L permethrin, 90.92 ng/L chlorpyrifos, respectively). Growth was inhibited by pesticide mixtures ?0.125 TU (1.04 ng/L lambda-cyhalothrin × 3.15 ng/L permethrin × 15.47 ng/L chlorpyrifos), and singly by lambda-cyhalothrin ?0.25 TU (5.50 ng/L), and permethrin ?0.167 TU (18.21 ng/L). The no observed effect concentrations (NOEC) for immobility and growth, for both mixture and single-pyrethroid exposure, were up to 8.0 and 12.0 times respectively lower than the corresponding NOEC for survival. The median effective concentrations (EC50) for growth (mixture and single-pyrethroid exposure) were up to 7.0 times lower than the respective LC50. This study reinforces that the integration of sublethal endpoints in monitoring efforts is powerful in discerning toxic effects that would otherwise be missed by solely utilizing traditional toxicity assessments. PMID:25630500

Hasenbein, Simone; Lawler, Sharon P; Geist, Juergen; Connon, Richard E

2015-05-01

159

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

SciTech Connect

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

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

1996-07-01

160

Effect of operating variables on the gas holdup in a large-scale slurry bubble column reactor operating with an organic liquid mixture  

Microsoft Academic Search

The effects of gas velocity, system pressure, and catalyst loading on gas holdup of Hâ, Nâ, CO, and CHâ in an organic mixture of hexanes were investigated in a 0.316 m diameter, 2.8 m height slurry bubble column reactor operating with a commercial Fischer-Tropsch iron-based catalyst. The data were obtained in the churn-turbulent flow regime with catalyst loading up to

Juan R. Inga; Badie I. Morsi

1999-01-01

161

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

PubMed

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

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

2003-03-15

162

A Combined Kinetic and Volatility Basis Set Approach to Model Secondary Organic Aerosol from Toluene and Diesel Exhaust/Meat Cooking Mixtures  

NASA Astrophysics Data System (ADS)

Secondary organic aerosol (SOA) is simulated for 6 outdoor smog chamber experiments using a SOA model based on a kinetic chemical mechanism in conjunction with a volatility basis set (VBS) approach. The experiments include toluene, a non-SOA-forming hydrocarbon mixture, diesel exhaust or meat cooking emissions and NOx, and are performed under varying conditions of relative humidity. SOA formation from toluene is modeled using a condensed kinetic aromatic mechanism that includes partitioning of lumped semi-volatile products in particle organic-phase and incorporates particle aqueous-phase chemistry to describe uptake of glyoxal and methylglyoxal. Modeling using the kinetic mechanism alone, along with primary organic aerosol (POA) from diesel exhaust (DE) /meat cooking (MC) fails to simulate the rapid SOA formation at the beginning hours of the experiments. Inclusion of a VBS approach with the kinetic mechanism to characterize the emissions and chemistry of complex mixture of intermediate volatility organic compounds (IVOCs) from DE/MC, substantially improves SOA predictions when compared with observed data. The VBS model includes photochemical aging of IVOCs and evaporation of POA after dilution. The relative contribution of SOA mass from DE/MC is as high as 95% in the morning, but substantially decreases after mid-afternoon. For high humidity experiments, aqueous-phase SOA fraction dominates the total SOA mass at the end of the day (approximately 50%). In summary, the combined kinetic and VBS approach provides a new and improved framework to semi-explicitly model SOA from VOC precursors in conjunction with a VBS approach that can be used on complex emission mixtures comprised with hundreds of individual chemical species.

Parikh, H. M.; Carlton, A. G.; Zhang, H.; Kamens, R.; Vizuete, W.

2011-12-01

163

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

EPA Science Inventory

This study was designed to define the degree of concentration addition found for mixtures of certain xenobiotics that are thought to act through a similar or different mode of toxic action for the acute mortality and sublethal growth toxicity endpoints, and for a freshwater fish ...

164

Organic matter characteristics in boreal forest soils under stands of silver birch, Norway spruce, and Norway spruce with a mixture of silver birch  

NASA Astrophysics Data System (ADS)

The aim was to study how tree species and a tree species mixture affect microbial C and N transformations and two major plant secondary compound groups, terpenes and phenolic compounds in soil. The study site was a tree-species experiment in middle-eastern part of Finland containing plots of 43-year-old silver birch, Norway spruce and Norway spruce with a mixture of silver birch (22 and 37 % birch of the total stem number). Soil was podzol and humus type mor. Samples were taken from the organic layer. C and N in the microbial biomass, rates of C mineralization (CO2 evolution), net N mineralization and nitrification, and concentrations of total water-soluble phenolic compounds, condensed tannins and different kind of terpenes were measured. Amounts of C and N in the microbial biomass and the rates of C mineralization and net N mineralization were all lower under spruce than birch, and particularly net N mineralization was stimulated by birch mixture. Concentrations of total water-soluble phenolic compounds were on a similar level, irrespective of tree species. However, there were less low-molecular-weight phenolics and more high-molecular-weight phenolics under spruce than birch. Concentrations of condensed tannins and both sesqui- and diterpenes were all higher under spruce than birch but the concentrations of triterpenes were similar in all soils. The difference between tree species was greatest with monoterpenes which were measured from both organic layer and soil atmosphere: high concentrations under spruce and negligible under birch. Birch mixture tended to decrease the concentrations of condensed tannins and mono-, sesqui- and diterpenes.

Smolander, A.; Kitunen, V.

2012-04-01

165

IN-SITU REMOVAL OF ARSENIC FROM GROUNDWATERS BY USING PERMEABLE REACTIVE BARRIERS OF ORGANIC MATTER\\/LIMESTONE MIXTURES  

Microsoft Academic Search

In this study, two different mixtures of municipal compost, limestone and zero-valent iron were assessed in two column experiments on acid rock treatment. The effluent solution was systematically analysed throughout the experiments and precipitates from both columns were withdrawn for scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffractometry were analyzed. Results showed that waters were cleaned of metals, arsenic

O. Gibert; J. de Pablo; J-L Cortina; C. Ayora; J. Cam

166

Combustibility and ignitability of mixtures of high-calorific metal powders and organic substances with the formula C x H y O z  

Microsoft Academic Search

1.Thermochemical calculations have shown that interaction between organic substances with the formula CxHyOz and magnesium or aluminum powder in accordance with the equation zMg+CxHyOz=zMgO+xC+yH2\\/2, when “z” and “x” are similar in value, is accompanied by the release of a large amount of heat (more than 1.5 kcal\\/g).2.The combustibility and ignitability of mixtures of magnesium, AM alloy, and aluminum powders with

V. V. Gorbunov; V. G. Khromov; A. A. Shidlovskii

1968-01-01

167

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

EPA Science Inventory

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

168

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

PubMed

Sourdough lactic acid bacteria, cultivated in wheat flour hydrolysate, produced antimould compounds. The antimould activity varied greatly among the strains and was mainly detected within obligately heterofermentative Lactobacillus spp. Among these, Lb. sanfrancisco CB1 had the largest spectrum. It inhibited moulds related to bread spoilage such as Fusarium, Penicillium, Aspergillus and Monilia. A mixture of acetic, caproic, formic, propionic, butyric and n-valeric acids, acting in a synergistic way, was responsible for the antimould activity. Caproic acid played a key role in inhibiting mould growth. PMID:9763693

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

1998-08-01

169

Mixture Experiments  

SciTech Connect

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

Piepel, Gregory F.

2007-12-01

170

ASSESSING THE INTERACTIONS OF ORGANIC COMPOUNDS DURING BIODEGRADATION OF COMPLEX WASTE MIXTURES BY NATURALLY OCCURRING BACTERIAL ASSEMBLAGES  

EPA Science Inventory

Selected organic chemicals were tested to determine the minimum concentrations at which complete inhibition of microbial degradative processes occurred. omplete inhibition did not occur at less than 2 g/L phenols 10 g/L toluene or n-butanol, and 100 g/L acetone, benzene or methan...

171

Olive orchard amended with two experimental olive mill wastes mixtures: Effects on soil organic carbon, plant growth and yield  

Microsoft Academic Search

Amendments of olive orchard soil with two different preparations of olive mill solid waste (OMWMs) at the rate of 9tonha?1 per year for five years in two different plots were compared with an industry standard soil amendment using urea. Both the OMWMs amendments showed significant increases in total organic carbon and humic substances in soil of approximately 40% and 58%,

Roberto Altieri; Alessandro Esposito

2008-01-01

172

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

PubMed

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

Kim, Minhee; Han, Junho; Hyun, Seunghun

2013-09-01

173

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

SciTech Connect

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

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

2011-01-01

174

Determination of the H isotopic composition of individual components in fine-scale mixtures of organic matter and phyllosilicates with the nanoscale secondary ion mass spectrometry.  

PubMed

When organic matter is mixed on a nanometer scale with clay minerals, the individual D/H ratios of the two H-bearing phases cannot be directly measured even with the nominal spatial resolution of nanoscale secondary ion mass spectrometry (NanoSIMS, 50-100 nm). To overcome this limitation, a new analytical protocol is proposed based on the deconvolution of the D(-)/H(-) and (16)OD(-)/(16)OH(-) ionic ratios measured by NanoSIMS. Indeed, since the yields of H(-) and (16)OH(-) are different for organics and clays, it should be theoretically possible to determine the mixing ratio of these two components in the area analyzed by the ion probe. Using organics with different D/H ratios, the interdependence of the D(-)/H(-) and (16)OD(-)/(16)OH(-) ionic ratios was determined in pure samples. Then using the H(-) and (16)OH(-) yields and the isotopic ratios measured on pure organic matter and clays, the expected D(-)/H(-) and (16)OD(-)/(16)OH(-) variations as a function of the mixing proportions were determined. These numerical predictions are consistent with measurements on laboratory prepared mixtures of D-rich organic matter and D-poor phyllosilicates, validating both the proposed experimental protocol and its use for meteorites. With an improvement of the precision of the ionic ratios by a factor of 10, it should possible to expend this protocol to samples having natural terrestrial D/H variations. Such an improvement could be attainable with the development of synthetic deuterated reference samples. PMID:23121456

Piani, Laurette; Remusat, Laurent; Robert, François

2012-12-01

175

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

Microsoft Academic Search

We are developing silent discharge plasma (SDP) oxidation technology as an alternative to incineration and as a post-incinerator treatment process for hazardous organic wastes. As an alternative to incineration, SDP apparatus has been coupled to a high-temperature packed-bed reactor, the plasma apparatus serving as a second stage for treating gaseous effluent from the packed bed. As a post- incinerator treatment

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

1992-01-01

176

Dynamics of carbon and nitrogen in a mixture of polycyclic aromatic hydrocarbons contaminated soil amended with organic residues.  

PubMed

Contamination of soil with polycyclic aromatic hydrocarbons (PAHs) through oil spills occurs frequently in Mexico. PAHs are highly resistant to degradation and restoration of these contaminated soils might be achieved by applying readily available organic material. A clayey soil was contaminated in the laboratory with different forms of PAHs, i.e. phenanthrene, anthracene and benzo(a)pyrene, and amended with maize or biosolids while production of carbon dioxide (CO2), dynamics of ammonia (NH4-), nitrate (NO3-) and PAHs were monitored. The largest CO2 production rate was found in soil added with maize and biosolids and the lowest in the unamended soil. The concentration of PAHs added to the sterilized soil did not change significantly over time and addition of organic material had no significant effect on it. The concentration of PAHs in unsterilized soil decreased sharply in the first weeks independent of addition of organic material and changes were small thereafter. After 100 days, 77% of benzo(a)pyrene was removed from soil, but 91% and 93% of phenanthrene and anthracene, respectively was removed. It was concluded that the autochthonous microbial population degraded phenanthrene, anthracene and benzo(a)pyrene, but neither biosolids nor maize accelerated the decomposition of PAHs or affected their residual concentration. PMID:17879847

Rivera-Espinoza, Y; Dendooven, L

2007-08-01

177

Separating Mixtures  

NSDL National Science Digital Library

Students learn how to classify materials as mixtures, elements or compounds and identify the properties of each type. The concept of separation of mixtures is also introduced since nearly every element or compound is found naturally in an impure state such as a mixture of two or more substances, and it is common that chemical engineers use separation techniques to separate mixtures into their individual components. For example, the separation of crude oil into purified hydrocarbons such as natural gas, gasoline, diesel, jet fuel and/or lubricants.

National Science Foundation GK-12 and Research Experience for Teachers (RET) Programs,

178

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

PubMed Central

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

2011-01-01

179

Liquid thermal conductivity of binary mixtures of difluoromethane (R32) and pentafluoroethane (R125)  

SciTech Connect

The thermal conductivities of refrigerant mixtures of difluoromethane (R32) and pentafluoroethane (R125) in the liquid phase are presented. The thermal conductivities were measured with the transient hot-wire method with one bare platinum wire. The experiments were conducted in the temperature range of 233--323 K and in the pressure range of 2--20 MPa. An empirical equation to describe the thermal conductivity of a near-azeotropic mixture, R32 + R125, is provided based on the measured 168 thermal conductivity data as a function of temperature and pressure. The dependence of thermal conductivity on the composition at different temperatures and pressures is also presented. The uncertainty of the measurements is estimated to be {+-}2%.

Ro, S.T.; Kim, M.S.; Jeong, S.U. [Seoul National Univ. (Korea, Republic of). Dept. of Mechanical Engineering

1997-07-01

180

Chiral mixtures  

NASA Astrophysics Data System (ADS)

An index evaluating the amount of chirality of a mixture of colored random variables is defined. Properties are established. Extreme chiral mixtures are characterized and examples are given. Connections between chirality, Wasserstein distances, and least squares Procrustes methods are pointed out.

Petitjean, Michel

2002-08-01

181

Mixtures and Solutions  

NSDL National Science Digital Library

Through three lessons and their four associated activities, students are introduced to concepts related to mixtures and solutions. Students consider how mixtures and solutions—and atoms and molecules—can influence new technologies developed by engineers. To begin, students explore the fundamentals of atoms and their structures. The building blocks of matter (protons, electrons, neutrons) are covered in detail. The next lesson examines the properties of elements and the periodic table—one method of organization for the elements. The concepts of physical and chemical properties are also reviewed. Finally, the last lesson introduces the properties of mixtures and solutions. A comparison of different mixtures and solutions, their properties and their separation qualities are explored.

Integrated Teaching and Learning Program,

182

Establishing a measure of reproducibility of ultrahigh-resolution mass spectra for complex mixtures of natural organic matter.  

PubMed

This study describes a method for evaluating the reproducibility of replicate mass spectra acquired for complex natural organic matter (NOM) samples analyzed by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry, with regard to both peak detection and peak magnitude. Because studies of NOM characterization utilize not only the emergence and disappearance of peaks but also changes in relative peak magnitude, it is important to establish that the differences between samples are significantly larger than those between sample replicates. Here, a method is developed for correcting strict signal-to-noise thresholds, along with a new scheme for assessing the reproducibility of peak magnitudes. Furthermore, a systematic approach for discerning when the comparison of samples by the presence or absence of peaks is appropriate and when it is necessary to compare based on the relative magnitude of the peaks is presented. A variety of 10 different types of NOM samples are analyzed in duplicate or triplicate instrumental injections or experimental extractions. A framework for these procedures is provided, and acceptable reproducibility levels are recommended. PMID:23075323

Sleighter, Rachel L; Chen, Hongmei; Wozniak, Andrew S; Willoughby, Amanda S; Caricasole, Paolo; Hatcher, Patrick G

2012-11-01

183

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

Microsoft Academic Search

Previous research has shown that the solubilities of dicarboxylic acids in certain electron-donor solvents are substantially increased in the presence of water. Information on solubilities, liquid-liquid equilibria and maximum-boiling ternary azeotropes was screened so as to identify other systems where codissolved water appears to enhance solvation of organic solutes in solvents. Several carboxylic acids, an alcohol, diols, and phenols were

Jane H. Lee; Vincent Van Brunt; C. Judson King

1994-01-01

184

Cooperative effect of temperature and linker functionality on CO2 capture from industrial gas mixtures in metal-organic frameworks: a combined experimental and molecular simulation study.  

PubMed

In this work, the cooperative effect of temperature and linker functionality on CO(2) capture in metal-organic frameworks (MOFs) was investigated using experimental measurements in combination with molecular simulations. To do this, four MOFs with identical topology but different functional groups on the linkers and three important CO(2)-containing industrial gas mixtures were adopted. The interplay between linker functionality and temperature was analyzed in terms of CO(2) storage capacity, adsorption selectivity, working capacity of CO(2) in temperature swing adsorption (TSA) processes, as well as sorbent selection parameter (S(ssp)). The results show that the effect of linker functionality on CO(2) capture performance in the MOFs is strongly interconnected with temperature: up to moderate pressures, the lower the temperature, the larger the effect of the functional groups. Furthermore, the modification of a MOF by introducing more complex functional groups can not only improve the affinity of framework for CO(2), but also reduce the free volume, and thus may contribute negatively to CO(2) capture capability when the packing effect is obvious. Therefore, when we design a new MOF for a certain CO(2) capture process operated at a certain temperature, the MOF should be designed to have maximized affinity for CO(2) but with a negligible or small effect caused by the reduction of free volume at that temperature and the corresponding operating pressure. PMID:22241397

Zhang, Wenjuan; Huang, Hongliang; Zhong, Chongli; Liu, Dahuan

2012-02-21

185

Large outdoor chamber experiments and computer simulations: (I) Secondary organic aerosol formation from the oxidation of a mixture of d-limonene and ?-pinene  

NASA Astrophysics Data System (ADS)

This work merges kinetic models for ?-pinene and d-limonene which were individually developed to predict secondary organic aerosol (SOA) formation from these compounds. Three major changes in the d-limonene and ?-pinene combined mechanism were made. First, radical-radical reactions were integrated so that radicals formed from both individual mechanisms all reacted with each other. Second, all SOA model species from both compounds were used to calculate semi-volatile partitioning for new semi-volatiles formed in the gas phase. Third particle phase reactions for particle phase ?-pinene and d-limonene aldehydes, carboxylic acids, etc. were integrated. Experiments with mixtures of ?-pinene and d-limonene, nitric oxide (NO), nitrogen dioxide (NO 2), and diurnal natural sunlight were carried out in a dual 270 m 3 outdoor Teflon film chamber located in Pittsboro, NC. The model closely simulated the behavior and timing for ?-pinene, d-limonene, NO, NO 2, O 3 and SOA. Model sensitivities were tested with respect to effects of d-limonene/?-pinene ratios, initial hydrocarbon to NO x (HC 0/NO x) ratios, temperature, and light intensity. The results showed that SOA yield ( YSOA) was very sensitive to initial d-limonene/?-pinene ratio and temperature. The model was also used to simulate remote atmospheric SOA conditions that hypothetically could result from diurnal emissions of ?-pinene, d-limonene and NO x. We observed that the volatility of the simulated SOA material on the aging aerosol decreased with time, and this was consistent with chamber observations. Of additional importance was that our simulation did not show a loss of SOA during the daytime and this was consistent with observed measurements.

Li, Qianfeng; Hu, Di; Leungsakul, Sirakarn; Kamens, Richard M.

186

Modeling secondary organic aerosol formation from xylene and aromatic mixtures using a dynamic partitioning approach incorporating particle aqueous-phase chemistry (II)  

NASA Astrophysics Data System (ADS)

Formation of secondary organic aerosol (SOA) is simulated for 14 outdoor smog chamber experiments using condensed gas-phase regulatory mechanisms and a new SOA framework. This framework is based on empirical parameterizations of independent chamber experiments and includes role of glyoxal and methylglyoxal in formation of particle aqueous-phase. To evaluate for regulatory applications, the chamber experiments include an urban non-SOA VOC mixture and NOx, with either injections of o/p-xylenes or toluene. The experiments are performed under varying conditions of relative humidity (RH) and in the presence of low initial background seed. Gas-particle partitioning of semi-volatile products into particle organic-phase is modeled using a dynamic partitioning approach with reactive uptake coefficient as the principal transport and kinetic parameter. Aqueous-phase SOA is predicted using formulations that describe the irreversible loss of both glyoxal and methylglyoxal to particle aqueous-phase. The predicted SOA mass in the new framework is evaluated using two regulatory gas-phase mechanisms - CB05 or SAPRC07 and, two regulatory parameterization schemes to predict semi-volatile product formation - an Odum-type two-product model and volatility basis-set (VBS). Predictions from the new SOA framework reproduce SOA mass within the uncertainty range of observations, irrespective of the choice of gas-phase mechanism and SOA parameterization scheme (root mean square error [RMSE] range of 0.18-3.08 ?g m-3). Further, model results suggest strong possibility of dominance of bulk-process under low seed conditions and surface-uptake process under high seed for aqueous-phase SOA formation. Sensitivity analysis to the hygroscopic nature of aqueous-phase SOA indicates an uncertainty of a factor of 2 in bulk-process and surface-uptake rates. In summary, the results strongly point to considering mass-transfer and kinetic limitations in regulatory air quality models at low ambient seed concentrations and highlight the importance of aqueous-phase SOA for aromatics under high-RH conditions.

Parikh, Harshal M.; Carlton, Annmarie G.; Zhou, Yang; Zhang, Haofei; Kamens, Richard M.; Vizuete, William

2012-09-01

187

Density functional theory of freezing for binary mixtures of 2D superparamagnetic colloids  

NASA Astrophysics Data System (ADS)

Density functional theory of freezing is used to study the phase diagram of a binary mixture of superparamagnetic colloidal particles in two dimensions. The particles interact via a purely repulsive potential that scales as the inverse cube of the inter-particle separation. This corresponds to a magnetic dipole interaction where the dipoles are induced by an external magnetic field applied normal to the plane. The pair correlation functions needed as input information in the density functional theory are calculated by the hypernetted chain integral equation closure. Considering the freezing into a disordered triangular solid phase, a spindle phase diagram is found for the susceptibility ratio 0.9 of the species, which changes to an azeotrope at a ratio 0.8. A eutectic-like phase diagram with an intervening solid phase emerges for the susceptibility ratio 0.7. The results are verifiable in real-space experiments on superparamagnetic colloids in external magnetic fields.

Mukherjee, Manjori; Mishra, Pankaj; Löwen, Hartmut

2014-11-01

188

Density functional theory of freezing for binary mixtures of 2D superparamagnetic colloids.  

PubMed

Density functional theory of freezing is used to study the phase diagram of a binary mixture of superparamagnetic colloidal particles in two dimensions. The particles interact via a purely repulsive potential that scales as the inverse cube of the inter-particle separation. This corresponds to a magnetic dipole interaction where the dipoles are induced by an external magnetic field applied normal to the plane. The pair correlation functions needed as input information in the density functional theory are calculated by the hypernetted chain integral equation closure. Considering the freezing into a disordered triangular solid phase, a spindle phase diagram is found for the susceptibility ratio 0.9 of the species, which changes to an azeotrope at a ratio 0.8. A eutectic-like phase diagram with an intervening solid phase emerges for the susceptibility ratio 0.7. The results are verifiable in real-space experiments on superparamagnetic colloids in external magnetic fields. PMID:25287741

Mukherjee, Manjori; Mishra, Pankaj; Löwen, Hartmut

2014-11-19

189

Detecting Specific Populations in Mixtures  

Microsoft Academic Search

Mixed stock analysis (MSA) estimates the relative contributions of distinct populations in a mixture of organisms. Increasingly,\\u000a MSA is used to judge the presence or absence of specific populations in specific mixture samples. This is commonly done by\\u000a inspecting the bootstrap confidence interval of the contribution of interest. This method has a number of statistical deficiencies,\\u000a including almost zero power

Joel Howard Reynolds; William David Templin

2004-01-01

190

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

Microsoft Academic Search

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

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

2006-01-01

191

Effect of Electrolyte and Temperature on Volatile Organic Compounds Removal from Wastewater Using Aqueous Surfactant Two-Phase System of Cationic and Anionic Surfactant Mixtures  

Microsoft Academic Search

Benzene, toluene, ethylbenzene, and xylene are frequently observed contaminants in industrial wastewaters causing concerns about environmental and health effects. An aqueous surfactant two-phase (ASTP) extraction system using mixtures of cationic and anionic surfactants have been shown to be a promising surfactant-based separation technique to concentrate solutes such as proteins and dyes from aqueous solution. A phase separation of a surfactant

Punjaporn Weschayanwiwat; Duanghathai Krutlert; John F. Scamehorn

2009-01-01

192

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

Microsoft Academic Search

In this study, two mixtures of municipal compost, limestone and, optionally, zero-valent iron were assessed in two column\\u000a experiments on acid mine treatment. The effluent solution was systematically analysed throughout the experiment and precipitates\\u000a from both columns were withdrawn for scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffractometry\\u000a analysis and, from the column containing zero-valent iron, solid digestion and sequential

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

2010-01-01

193

Simulation of nonazeotropic refrigerant mixtures for use in a dual-circuit refrigerator/freezer with countercurrent heat exchangers  

SciTech Connect

The paper discusses a refrigerator/freezer (RF) system that has two complete and independent refrigeration cycles for the two compartments. It uses a non-azeotropic refrigerant mixture (NARM) in each cycle and countercurrent heat exchangers throughout. In a standard cabinet, this RF appears to provide energy savings of 24%, compared to current U.S. RF designs. The NARMs modeled with the best performance included R-32/-152a, R-22/-142b, and R-32/-142b. An 18% improvement can be expected from the dual-circuit system using R-12 alone, and an additional 6% improvement can be gained by replacing R-12 with the selected NARMs in countercurrent heat exchangers. The advantages of the system include greatly reduced energy consumption, easy temperature and humidity control for each compartment, no humidity or odors transferred between compartments, and increased time between defrost cycles.

Bare, J.C.; Gage, C.L.; Radermacher, R.; Jung, D.

1991-01-01

194

Organics.  

ERIC Educational Resources Information Center

Presents water analysis literature for 1978. This review is concerned with organics, and it covers: (1) detergents and surfactants; (2) aliphatic and aromatic hydrocarbons; (3) pesticides and chlorinated hydrocarbons; and (4) naturally occurring organics. A list of 208 references is also presented. (HM)

Chian, Edward S. K.; DeWalle, Foppe B.

1978-01-01

195

Influence of catalyticity of a porous medium on the concentration limit of filtration combustion of a water-organic mixture in a reversible flow reactor  

NASA Astrophysics Data System (ADS)

The problem on oxidation purification of water in a reversible flow reactor with the use of a catalyst has been studied by numerical methods. We have made comparative studies of the concentration limits of mixture combustion attained in inert and catalytic porous media reactors at varied values of the liquid flow rate, the reactor length, the heat loss coefficient, and the size of the packed bed. It has been established that the use of a catalyst leads to an insignificant decrease in the concentration limit: 11.6% against 13.4% (adiabatic case) and 12.5% against 13.9% (standard insulation).

Dobrego, K. V.; Koznacheev, I. A.

2012-09-01

196

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

SciTech Connect

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

Stephen M Bajorek; J. Schnelle

2002-05-01

197

CHEMICAL MIXTURES: CONSEQUENCES FOR WATER QUALITY  

EPA Science Inventory

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

198

Hand-held gas chromatography-ion mobility spectrometry for on-site analysis of complex organic mixtures in air or vapors over waste sites  

SciTech Connect

The strengths of Ion mobility spectrometry (IMS) are low detection limits, a wide range of application, and simplicity of design and operation. The gentle ionization processes used in IMS impart a measure of selectivity to its response. However, atmospheric pressure chemical ionization with compounds of comparable proton affinities leads to mobility spectra for which interpretive and predictive models do not exist. An alternative approach for the analysis of complex mixtures with IMS is the use of a separation device such as a gas chromatograph (GC) as an inlet. Results suggest that an IMS cell temperature of ca. 150{degrees} to 175{degrees}C provided mobility spectra with suitable spectral detail without the complications of ion-molecule clusters or fragmentation. Significant fluctuation in peak heights were observed over a 30 day test period. Neural network pattern identification techniques were applied to data obtained at room temperature and at 150{degrees}. Results showed that spectral variables within compound classes as insufficient to distinguish related compounds when mobility data was obtained using the commercial room temperature IMS cell. Similar but less severe difficulty was encountered using the 150{degrees} data. 5 refs., 3 figs., 2 tabs.

Bell, S.C. (Los Alamos National Lab., NM (USA)); Eiceman, G.A. (New Mexico State Univ., Las Cruces, NM (USA). Dept. of Chemistry)

1991-01-01

199

Biological degradation of a mixture of municipal wastewater and organic garbage leachate in expanded bed anaerobic reactors and a zeolite filter.  

PubMed

Municipal wastewater was amended with organic garbage leachates at a concentration around 700 mgCOD(soluble)/L and fed to three different anaerobic systems to compare their performance: a down flow fluidized bed (DFFB), an expanded granular sludge bed (EGSB) and a zeolite-packed anaerobic filter reactor (ZPF). The DFFB and EGSB reactors were operated at HRT of 6 and 4 h and the ZPF reactor at 12 and 36 h. Organic loads rate for the DFFB reactor were 2.3+/-0.9 and 4.8+/-1.8 gCOD/L.d, with removal efficiencies around 40% and a methane productivity of 0.2+/-0.03 L/L(reactor).d. For the EGSB reactor, organic loads tested were 2.1+/-0.9 and 4.3+/-1.3 gCOD/L.d, removal efficiencies attained were of 77.6+/-12.7% and 84.4+/-4.9%, respectively at both conditions and total suspended solids were removed in 54.6+/-19.3%, while methane productivity at 4 h HRT was of 1.29+/-0.4 L/L(reactor).d. The ZPF reactor was operated at lower organic loading rates, 1.4+/-0.27 and 0.42+/-0.13 gCOD/L.d and attained removal efficiencies of 48+/-18% and 83+/-8%, respectively, reaching a methane productivity of 0.21+/-0.09 and 0.12+/-0.04 L/L(reactor).d, 83+/-8.0% of total suspended solids were retained in the reactor and as HRT was increased ammonium concentrations increased in 39%. Specific methanogenic activity in all systems was around 0.2 gCOD-CH(4)/gVSS d. PMID:19237766

Castilla, P; Aguilar, L; Escamilla, M; Silva, B; Milán, Z; Monroy, O; Meraz, M

2009-01-01

200

Mixtures Research at NIEHS: An Evolving Program  

PubMed Central

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

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

2014-01-01

201

The Mixtures Lab  

NSDL National Science Digital Library

The representation illustrates the separation of mixtures using physical properties. The interactive simulation allows "lab attendants" to separate mixtures using virtual tools. Separation mechanisms are chosen based upon substances' physical properties, and findings are recorded in a chart.

202

Element, Mixture, Compound  

NSDL National Science Digital Library

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

National Science Foundation GK-12 and Research Experience for Teachers (RET) Programs,

203

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

204

Remediation of the effect of adding cyanides on an algal/bacterial treatment of a mixture of organic pollutants in a continuous photobioreactor.  

PubMed

The effect of inorganic pollutants on the treatment of organic pollutants using algal/bacterial microcosm was investigated in a continuous photobioreactor. The microcosm was composed of Chlorella vulgaris MM1 and Pseudomonas MT1 and was able to efficiently treat artificial waste-water contaminated with 6.4 salicylate and 2.2 mM phenol at a hydraulic retention time of 4 days. No negative effect was recorded when the waste-water was supplemented with 1.6 mM thiocyanate; however, the treatment efficiency severely deteriorated when the system was challenged with 0.74 mM cyanide. Addition of 2 g NaHCO3 l(-1) did not improve the efficiency of the treatment. Toxicity of the pollutants to the alga was cyanide > thiocyanate > phenol > salicylate. The high toxicity of the waste-water was eliminated either by a 25-fold dilution or by photocatalytic pre-treatment which allowed the subsequent efficient biological treatment. PMID:24930096

Essam, Tamer; ElRakaiby, Marwa; Agha, Azza

2014-09-01

205

First direct observation of secondary organic aerosol formation during cloud condensation-evaporation cycles in isoprene photo-oxidation reacting mixtures (CUMULUS project)  

NASA Astrophysics Data System (ADS)

Several field observations, laboratory and model studies suggest a potentially important role of cloud droplets in forming additional secondary organic aerosol (SOA) (Sorooshian et al., 2007; Altieri et al., 2008; Couvidat et al., 2013). While this SOAaq hypothesis seems to be robust and is considered quite established, so far, no direct observations of such a process have been provided. Recently a consortium of five laboratories has joined theirs efforts in a series of experimental simulation experiments to try to bring a direct confirmation of this hypothesis: the CUMULUS project (CloUd MULtiphase chemistry of organic compoUndS in the troposphere). The aim of the present work is to study SOA formation from isoprene photo-oxidation during cloud condensation-evaporation cycles. The chemistry occurring in the gaseous, particulate and aqueous phases, and the exchange between these phases were investigated through an original multiphase approach in a simulation chamber. Experiments were performed in the CESAM chamber (Wang et al., 2011) which was designed to investigate multiphase processes under realistic actinic flux, and accurate control of both temperature and relative humidity. A protocol was designed to generate cloud events in the simulation chamber, it has allowed us to generate clouds lasting for ca. 10 minutes in the presence of light and many clouds could be generated in a single experiment. Connected to the chamber, a large panel of instruments was used to monitor the gas-phase and the particulate phase during experiments. Gas-phase composition was analyzed in-situ via a Fourier Transform Infrared Spectrometer (FTIR) and a Proton Transfer Reaction Mass Spectrometer (PTR-TOF-MS) as well as NOx and O3 analyzers. A Scanning Mobility Particle Sizer (SMPS) measured dried SOA size distributions and total concentrations inside the chamber. An Aerodyne High Resolution Time-Of-Flight Aerosol Mass Spectrometer (HR-TOF-AMS) was also used to investigate aerosol composition. Cloud droplets size distributions were measured by a white light Optical Particle Counter (OPC). In each experiment, around 800 ppb of isoprene was injected in the chamber together with HONO under dry conditions before irradiation. In all experiments, the impact of the cloud generation on the gaseous and particulate phases has been highlighted, suggesting a significant production of SOA from isoprene photo-oxidation by interactions with cloud droplets. The overall results in additional SOA mass production, the dynamic of its mass concentration and some insight of its chemical composition will be presented. Altieri, K. et al. (2008). Atmospheric Environment 42(7): 1476-1490. Couvidat, F. et al. (2013). Environmental Science & Technology 47(2): 914-922. Sorooshian, A. et al. (2007). Environmental Science & Technology 41(13): 4647-4654. Wang, J. et al. (2011). Atmospheric Measurement Techniques 4(11): 2465-2494.

Brégonzio-Rozier, Lola; Siekmann, Frank; Giorio, Chiara; Temime-Roussel, Brice; Pangui, Edouard; Morales, Sébastien; Ravier, Sylvain; Monod, Anne; Doussin, Jean-François

2014-05-01

206

Mixture or Solution?  

NSDL National Science Digital Library

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

steve burns

2011-10-09

207

We study the continuous extractive distillation of minimum and maximum boiling azeotropic mixtures A-B with a heavy or a light entrainer E, intending to assess its feasibility based on thermodynamic insights.  

E-print Network

#12;#12;Abstract We study the continuous extractive distillation of minimum and maximum boiling on operating parameters: distillate product purity and recovery, reflux ratio R and entrainer ­ feed flow rate. For the 1.0-2 class both A and B can be distillated. For one of them there exists a maximum entrainer - feed

Mailhes, Corinne

208

Organs to go ...  

NSDL National Science Digital Library

In this activity the students design an experiment to investigate the storage of an organ before a transplant operation is performed. Essentially, the students create a "slush" type mixture to store the organ.

Sheryl Burris Deets (Belleville West High School REV)

1995-06-30

209

Assessment of solid reactive mixtures for the development of biological permeable reactive barriers  

Microsoft Academic Search

Solid reactive mixtures were tested as filling material for the development of biological permeable reactive barriers for the treatment of heavy metals contaminated waters. Mixture selection was performed by taking into account the different mechanisms operating in sulphate and cadmium removal with particular attention to bioprecipitation and sorption onto the organic matrices in the mixtures. Suspensions of eight reactive mixtures

Francesca Pagnanelli; Carolina Cruz Viggi; Sara Mainelli; Luigi Toro

2009-01-01

210

Method of extracting iodine from liquid mixtures of iodine, water and hydrogen iodide  

DOEpatents

The components of a liquid mixture consisting essentially of HI, water and at least about 50 w/o iodine are separated in a countercurrent extraction zone by treating with phosphoric acid containing at least about 90 w/o H.sub.3 PO.sub.4. The bottom stream from the extraction zone is substantially completely molten iodine, and the overhead stream contains water, HI, H.sub.3 PO.sub.4 and a small fraction of the amount of original iodine. When the water and HI are present in near-azeotropic proportions, there is particular advantage in feeding the overhead stream to an extractive distillation zone wherein it is treated with additional concentrated phosphoric acid to create an anhydrous HI vapor stream and bottoms which contain at least about 85 w/o H.sub.3 PO.sub.4. Concentration of these bottoms provides phosphoric acid infeed for both the countercurrent extraction zone and for the extractive distillation zone.

Mysels, Karol J. (La Jolla, CA)

1979-01-01

211

Messin' with Mixtures  

NSDL National Science Digital Library

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

2014-09-18

212

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

PubMed

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

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

2014-07-11

213

Perception of trigeminal mixtures.  

PubMed

The trigeminal system is a chemical sense allowing for the perception of chemosensory information in our environment. However, contrary to smell and taste, we lack a thorough understanding of the trigeminal processing of mixtures. We, therefore, investigated trigeminal perception using mixtures of 3 relatively receptor-specific agonists together with one control odor in different proportions to determine basic perceptual dimensions of trigeminal perception. We found that 4 main dimensions were linked to trigeminal perception: sensations of intensity, warmth, coldness, and pain. We subsequently investigated perception of binary mixtures of trigeminal stimuli by means of these 4 perceptual dimensions using different concentrations of a cooling stimulus (eucalyptol) mixed with a stimulus that evokes warmth perception (cinnamaldehyde). To determine if sensory interactions are mainly of central or peripheral origin, we presented stimuli in a physical "mixture" or as a "combination" presented separately to individual nostrils. Results showed that mixtures generally yielded higher ratings than combinations on the trigeminal dimensions "intensity," "warm," and "painful," whereas combinations yielded higher ratings than mixtures on the trigeminal dimension "cold." These results suggest dimension-specific interactions in the perception of trigeminal mixtures, which may be explained by particular interactions that may take place on peripheral or central levels. PMID:25500807

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

2015-01-01

214

Kinematic separation of mixtures  

SciTech Connect

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.

Goldshtik, M.; Husain, H.S.; Hussain, F. (Department of Mechanical Engineering, University of Houston, Houston, Texas 77204-4792 (United States))

1992-06-15

215

Separating a Mixture  

NSDL National Science Digital Library

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

Perkins School for the Blind

2012-07-12

216

Home Connections: Demystifying Mixtures  

NSDL National Science Digital Library

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

Kathleen Damonte

2003-10-01

217

Condensate Mixtures and Tunneling  

SciTech Connect

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.

Timmermans, E.

1998-09-14

218

Flexible and Robust Bayesian Classification by Finite Mixture Models  

E-print Network

by a weighted sum of mixture distributions. In general, finite Gaussian mixture models (FGM) are used. However [6] in order to improve the density estimates of FGM. In this paper, we extend its use to FTM. This paper is organized as follows. In Section 2, FGM and FTM are recalled. In Section 3, the use

Rattray, Magnus

219

Mixture toxicity and tissue interactions of Cd, Cu, Pb and Zn in earthworms ( Oligochaeta) in laboratory and field soils: A critical evaluation of data  

Microsoft Academic Search

Soil organisms inhabiting contaminated field sites are usually exposed to mixtures of toxicants. In such mixtures, toxicants can interact to express enhanced or weakened toxicity. Therefore, mixture effects should be considered in risk assessment methods for polluted soils. Data on mixture toxicity to soil organisms are scarce, however. In this paper, data on sublethal toxicity and tissue concentrations of Cd,

L. Weltje

1998-01-01

220

Simulation of nonazeotropic refrigerant mixtures for use in a dual-circuit refrigerator/freezer with countercurrent heat exchanges  

SciTech Connect

The paper discusses the simulation of Non-azeotropic Refrigerant Mixtures (NARMs) for use in a dual-circuit refrigerator/freezer (RF) with countercurrent heat exchangers. The simulated RF has two complete and independent refrigeration cycles for its two compartments. It uses a NARM in each cycle and countercurrent heat exchangers throughout. In a standard cabinet, the RF is simulated to provide energy savings of 24 percent compared to current U.S. RF designs. The NARMs modeled with the best performance are R-32/-152a, R-32/-142b, and R-22/-142b. An 18 percent improvement can be expected from the dual-circuit system using R-12 alone, and an additional 6 percent improvement can be gained by replacing R-12 with the selected NARMs in countercurrent heat exchangers. Advantages of the system include greatly reduced energy consumption, easy temperature and humidity control for each compartment, no humidity or odors transferred between compartments, and increased time between defrost cycles. Disadvantages include additional hardware requirements, compressor size, and the difficulties of using a NARM.

Bare, J.C.; Gage, C.L.; Radermacher, R.; Jung, D.S.

1992-01-01

221

Separating gaseous isotope mixtures  

Microsoft Academic Search

A process is described for separating gaseous isotope mixtures having the general molecular composition X\\/sub n1\\/\\/sup (1)\\/ X\\/sub n2\\/\\/sup (2)\\/...X\\/sub ni\\/\\/sup (i)\\/, where a constituent X\\/sup (k)\\/ can be replaced by an isotope anti X--\\/sup (k)\\/ by irradiation with laser light.

Rosenberger

1977-01-01

222

Lab Investigation Mixture Separation  

NSDL National Science Digital Library

This is a lab that is designed to have students write a lab procedure and separate out mixture of substances with different properties. It is also a good introduction to the different lab equipment that they will be using through out the year.

223

Mass spectrometer mixture calibrations  

Microsoft Academic Search

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

Hicks

1986-01-01

224

POTENTIAL EMISSIONS OF HAZARDOUS ORGANIC COMPOUNDS FROM SEWAGE SLUDGE INCINERATION  

EPA Science Inventory

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

225

Combustion of Gaseous Mixtures  

NASA Technical Reports Server (NTRS)

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.

Duchene, R

1932-01-01

226

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

EPA Science Inventory

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

227

Challenges in Regulating Pesticide Mixtures  

Microsoft Academic Search

This paper introduces the field of mixture toxicity and the challenges in regulating pesticide mixtures. Even though pesticides are unique chemical stressors designed to have biological activity that can affect a number of nontarget species, they are intentionally placed into the environment in large quantities. Currently, methods and terminology for evaluating mixture toxicity are poorly established. The most common approach

Michael Lydy; Jason Belden; Craig Wheelock; Bruce Hammock; Debra Denton

2004-01-01

228

Physicochemical properties of formaldehyde-ice-dust mixtures  

Microsoft Academic Search

One of the spectacular surprises of the recent spacecraft encounters with the comet Halley was the discovery of complex organic molecules associated with dust grains in the coma, namely the CHON particles. Formaldehyde oligomers were identified as a constituent of the complex mixture that constitutes the organic component of the dust. These oligomers when end-capped with water are observed in

D. C. Boice; D. W. Naegeli; W. F. Huebner

1989-01-01

229

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

PubMed Central

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

Rice, James W.; Suuberg, Eric M.

2010-01-01

230

Equilibrium phase diagrams and water absorption properties of aqueous mixtures of malonic acid and inorganic salts  

Microsoft Academic Search

Tropospheric aerosols are usually complex mixtures of inorganic and organic components. Although the thermodynamic properties of inorganic aerosols have been widely studied, the effect of organics on such properties is still under discussion. Solubility in water, water activity of aqueous solutions, deliquescence relative humidity (DRH), eutonic composition, and eutonic DRH were determined for bulk mixtures of malonic acid with ammonium

D. Salcedo; G. Salgado-Olea

2006-01-01

231

Oxidative particle mixtures for groundwater treatment  

DOEpatents

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.

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

2000-01-01

232

Biogeochemistry of two types of permeable reactive barriers, organic carbon and iron-bearing organic carbon for mine drainage treatment: Column experiments  

Microsoft Academic Search

Permeable reactive barriers (PRBs) are an alternative technology to treat mine drainage containing sulfate and heavy metals. Two column experiments were conducted to assess the suitability of an organic carbon (OC) based reactive mixture and an Fe0-bearing organic carbon (FeOC) based reactive mixture, under controlled groundwater flow conditions. The organic carbon mixture contains about 30% (volume) organic carbon (composted leaf

Qiang Guo; David W. Blowes

2009-01-01

233

Toxicological approaches to complex mixtures.  

PubMed Central

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

Mauderly, J L

1993-01-01

234

Predicted mixture toxic pressure relates to observed fraction of benthic macrofauna species impacted by contaminant mixtures.  

PubMed

Species sensitivity distributions (SSDs) quantify fractions of species potentially affected in contaminated environmental compartments using test species sensitivity data. The present study quantitatively describes associations between predicted and observed ecological impacts of contaminant mixtures, based on monitoring data of benthic macroinvertebrates. Local mixture toxic pressures (multisubstance potentially affected fraction of species [msPAF]) were quantified based on measured concentrations of 45 compounds (eight metals, 16 chlorinated organics, mineral oil, 16 polycyclic aromatic hydrocarbons, four polychlorinated biphenyls), using acute as well as chronic 50%-effective concentration-based SSD-modeling combined with bioavailability and mixture modeling. Acute and chronic toxic pressures were closely related. Generalized linear models (GLMs) were derived to describe taxon abundances as functions of environmental variables (including acute toxic pressure). Acute toxic pressure ranged from 0 to 42% and was related to abundance for 74% of the taxa. Habitat-abundance curves were generated using the GLMs and Monte Carlo simulation. Predicted abundances for the taxa were associated with acute mixture toxic pressure in various ways: negative, positive, and optimum abundance changes occurred. Acute toxic pressure (msPAF) was associated almost 1:1 with the observed fraction of taxa exhibiting an abundance reduction of 50% or more. The findings imply that an increase of mixture toxic pressure associates to increased ecological impacts in the field. This finding is important, given the societal relevance of SSD model outputs in environmental policies. PMID:22729941

Posthuma, Leo; de Zwart, Dick

2012-09-01

235

Continuous dielectrophoretic separation of cell mixtures.  

PubMed

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

Pohl, H A; Kaler, K

1979-03-01

236

Mixtures of functionalized colloids on substrates  

NASA Astrophysics Data System (ADS)

Patchy particles are a class of colloids with functionalized surfaces. Through surface functionalization, the strength and directionality of the colloidal interactions are tunable allowing control over coordination of the particle. Exquisite equilibrium phase diagrams of mixtures of coordination two and three have been reported. However, the kinetics of self-organization and the feasibility of the predicted structures are still largely unexplored. Here, we study the irreversible aggregation of these mixtures on a substrate, for different fractions of two-patch particles. Two mechanisms of mass transport are compared: diffusion and advection. In the diffusive case, an optimal fraction is found that maximizes the density of the aggregate. By contrast, for advective transport, the density decreases monotonically with the fraction of two-patch colloids, in line with the behavior of the liquid density on the spinodal of the equilibrium phase diagram.

Dias, C. S.; Araújo, N. A. M.; Telo da Gama, M. M.

2013-10-01

237

Organic Vegetable Organic Vegetable  

E-print Network

Organic Vegetable Production Organic Vegetable Production Organic Vegetable Production ID-316 #12. #12;Organic Vegetable Production TABLE OF CONTENTS: Introduction ..........................................11 Organic Insect Management (Table 3) ............13 Organic Disease Management (Table 4

238

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

ERIC Educational Resources Information Center

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

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

1989-01-01

239

Surface tensions of solutions containing dicarboxylic acid mixtures  

NASA Astrophysics Data System (ADS)

Organic solutes tend to lower the surface tension of cloud condensation nuclei, allowing them to more readily activate. The surface tension of various dicarboxylic acid aerosol mixtures was measured at 20 °C using the Wilhelmy plate method. At lower concentrations, the surface tension of a solution with equi-molar mixtures of dicarboxylic acids closely followed that of a solution with the most surface-active organic component alone. Measurements of surface tension for these mixtures were lower than predictions using Henning's model and the modified Szyszkowski equation, by ?1-2%. The calculated maximum surface excess (?max) and inverse Langmuir adsorption coefficient (?) from the modified Szyszkowski equation were both larger than measured values for 6 of the 7 mixtures tested. Accounting for the reduction in surface tension in the Köhler equation reduced the critical saturation ratio for these multi-component mixtures - changes were negligible for dry diameters of 0.1 and 0.5 ?m, but a reduction from 1.0068 to 1.0063 was seen for the 4-dicarboxylic acid mixture with a dry diameter of 0.05 ?m.

Lee, Jae Young; Hildemann, Lynn M.

2014-06-01

240

COMPLEX MIXTURES AND GROUNDWATER QUALITY  

EPA Science Inventory

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

241

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.

242

Identification and evaluation of pyrethroid insecticide mixtures in urban sediments.  

PubMed

Organochlorine, organophosphorous, and pyrethroid insecticides frequently have been detected together as mixtures in stream sediments. To simplify mixture analyses, additive toxic responses usually are assumed but rarely are confirmed, especially for compounds with similar modes of action. The first objective of the present study was to screen a database of 24 different pesticides and 94 urban-stream sediment samples collected throughout central and northern California (USA) to identify compounds and partial mixtures that dominated sample toxicity to Hyalella azteca. Pyrethroids and chlorpyrifos were the most toxicologically relevant compounds in terms of detection frequency, contribution to overall sample toxicity, and co-occurrence in the most common mixture patterns. Organochlorine insecticides were the least toxicologically relevant compounds, with only a small percentage of samples exceeding predefined screening values. The second objective was to confirm that mixtures of type I and type II pyrethroids display additive responses. Ten-day sediment toxicity tests of binary pesticide mixtures were conducted using H. azteca as the test organism. Observed dose-response curves were compared to those predicted from concentration-addition and independent-action models. Model deviation ratios (MDRs) were calculated at the median effect level to quantify the magnitudes of deviation between observed and predicted curves. Whereas the concentration-addition model adequately predicted toxicity for all the pyrethroid mixtures (MDRs within a factor of two), dose-response values deviated from additivity enough to warrant further investigation. PMID:19245272

Trimble, Andrew J; Weston, Donald P; Belden, Jason B; Lydy, Michael J

2009-08-01

243

Bridging environmental mixtures and toxic effects  

PubMed Central

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

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

2012-01-01

244

A review on the separation of benzene\\/cyclohexane mixtures by pervaporation processes  

Microsoft Academic Search

Separation of benzene (Bz) and cyclohexane (Chx) is one of the most challenging processes in the chemical industry. On account of the only 0.6°C difference in volatilities of the two components, conventional distillation processes are not practical. Azeotropic distillation and extractive distillation, on the other hand, although feasible and in use in many industries, are accompanied by high capital and

J. P. Garcia Villaluenga; A. Tabe-Mohammadi

2000-01-01

245

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

PubMed

The fate and biological effects of chemical mixtures in the environment are receiving increased attention from the scientific and regulatory communities. Understanding the behavior and toxicity of metal mixtures poses unique challenges for incorporating metal-specific concepts and approaches, such as bioavailability and metal speciation, in multiple-metal exposures. To avoid the use of oversimplified approaches to assess the toxicity of metal mixtures, a collaborative 2-yr research project and multistakeholder group workshop were conducted to examine and evaluate available higher-tiered chemical speciation-based metal mixtures modeling approaches. The Metal Mixture Modeling Evaluation project and workshop achieved 3 important objectives related to modeling and interpretation of biological effects of metal mixtures: 1) bioavailability models calibrated for single-metal exposures can be integrated to assess mixture scenarios; 2) the available modeling approaches perform consistently well for various metal combinations, organisms, and endpoints; and 3) several technical advancements have been identified that should be incorporated into speciation models and environmental risk assessments for metals. Environ Toxicol Chem 2015;34:721-725. © 2015 SETAC. PMID:25809105

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

2015-04-01

246

Equilibrium phase diagrams and water absorption properties of aqueous mixtures of malonic acid and inorganic salts.  

NASA Astrophysics Data System (ADS)

Tropospheric aerosols are usually complex mixtures of inorganic and organic components. Although the thermodynamic properties of inorganic aerosols have been widely studied, the effect of organics on such properties is still under discussion. Solubility in water, water activity of aqueous solutions, deliquescence relative humidity (DRH), eutonic composition, and eutonic DRH were determined for bulk mixtures of malonic acid with ammonium sulfate, ammonium bisulfate, and ammonium nitrate at 25oC over the full range of composition (from 0 wt% to the solubility limit of the mixture components). The data was used to construct equilibrium phase diagrams, which show the phase of the mixtures as a function of total composition, dry mixture composition, water content, and ambient relative humidity. Measured water activity of liquid solutions was compared with an extended Zdanovskii-Stokes-Robinson (ZSR) expression, which then was used to predict water absorption of the mixtures.

Salcedo, D.; Salgado-Olea, G.

2006-12-01

247

Modeling and analysis of personal exposures to VOC mixtures using copulas.  

PubMed

Environmental exposures typically involve mixtures of pollutants, which must be understood to evaluate cumulative risks, that is, the likelihood of adverse health effects arising from two or more chemicals. This study uses several powerful techniques to characterize dependency structures of mixture components in personal exposure measurements of volatile organic compounds (VOCs) with aims of advancing the understanding of environmental mixtures, improving the ability to model mixture components in a statistically valid manner, and demonstrating broadly applicable techniques. We first describe characteristics of mixtures and introduce several terms, including the mixture fraction which represents a mixture component's share of the total concentration of the mixture. Next, using VOC exposure data collected in the Relationship of Indoor Outdoor and Personal Air (RIOPA) study, mixtures are identified using positive matrix factorization (PMF) and by toxicological mode of action. Dependency structures of mixture components are examined using mixture fractions and modeled using copulas, which address dependencies of multiple variables across the entire distribution. Five candidate copulas (Gaussian, t, Gumbel, Clayton, and Frank) are evaluated, and the performance of fitted models was evaluated using simulation and mixture fractions. Cumulative cancer risks are calculated for mixtures, and results from copulas and multivariate lognormal models are compared to risks calculated using the observed data. Results obtained using the RIOPA dataset showed four VOC mixtures, representing gasoline vapor, vehicle exhaust, chlorinated solvents and disinfection by-products, and cleaning products and odorants. Often, a single compound dominated the mixture, however, mixture fractions were generally heterogeneous in that the VOC composition of the mixture changed with concentration. Three mixtures were identified by mode of action, representing VOCs associated with hematopoietic, liver and renal tumors. Estimated lifetime cumulative cancer risks exceeded 10(-3) for about 10% of RIOPA participants. Factors affecting the likelihood of high concentration mixtures included city, participant ethnicity, and house air exchange rates. The dependency structures of the VOC mixtures fitted Gumbel (two mixtures) and t (four mixtures) copulas, types that emphasize tail dependencies. Significantly, the copulas reproduced both risk predictions and exposure fractions with a high degree of accuracy, and performed better than multivariate lognormal distributions. Copulas may be the method of choice for VOC mixtures, particularly for the highest exposures or extreme events, cases that poorly fit lognormal distributions and that represent the greatest risks. PMID:24333991

Su, Feng-Chiao; Mukherjee, Bhramar; Batterman, Stuart

2014-02-01

248

Some results on Gaussian mixtures  

NASA Astrophysics Data System (ADS)

We investigate Gaussian mixtures with independent components, whose parameters are numerically estimated. A decomposition of a Gaussian mixture is presented when the components have a common variance. We introduce a shifted and scaled t-Student distribution as an approximation for the distribution of Gaussian mixtures when their components have a common mean and develop a hypothesis test for testing the equality of the components means. Finally, we analyse the fitness of the approximate model to the logarithmic daily returns of the Portuguese stock index PSI-20.

Felgueiras, Miguel; Santos, Rui; Martins, João Paulo

2014-10-01

249

VOCs, Pesticides, Nitrate, and Their Mixtures in Groundwater Used for  

E-print Network

VOCs, Pesticides, Nitrate, and Their Mixtures in Groundwater Used for Drinking Water in the United areas. For each sample, as many as 60 volatile organic compounds (VOCs), 83 pesticides, and nitrate were to have an anthropogenic origin. VOCs were detected more frequently (44%) than pesticides (38

250

Room temperature ionic liquids and their mixtures—a review  

Microsoft Academic Search

Room temperature ionic liquids are salts that are liquid at room temperature and their use as catalysts and catalytic support has been studied extensively. They are also being considered as “green solvents” for various separation processes. Recent measurements reported on the properties of pure ionic liquids and their mixtures, including gas and liquid solubility in common organic solvents will be

K. N Marsh; J. A Boxall; R Lichtenthaler

2004-01-01

251

Formulation of Environmentally Sound Waste Mixtures for Land Application  

Microsoft Academic Search

Major impediments to the land application of coal combustion byproducts (fly ash) for crop fertilization have been the presence of heavy metals and their relatively low and imbalanced essential nutrient concentration. Although nutrient deficiencies, in particular N, P, and K, may be readily augmented by adding organic wastes such as sewage sludge and animal manure, the indiscriminate application of mixtures

Arnold W. Schumann; Malcolm E. Sumner

2004-01-01

252

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

DOEpatents

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

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

1995-09-26

253

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

DOEpatents

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

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

1995-01-01

254

Gene expression responses in male fathead minnows exposed to binary mixtures of an estrogen and antiestrogen  

Microsoft Academic Search

BACKGROUND: Aquatic organisms are continuously exposed to complex mixtures of chemicals, many of which can interfere with their endocrine system, resulting in impaired reproduction, development or survival, among others. In order to analyze the effects and mechanisms of action of estrogen\\/anti-estrogen mixtures, we exposed male fathead minnows (Pimephales promelas) for 48 hours via the water to 2, 5, 10, and

Natàlia Garcia-Reyero; Kevin J Kroll; Li Liu; Edward F Orlando; Karen H Watanabe; María S Sepúlveda; Daniel L Villeneuve; Edward J Perkins; Gerald T Ankley; Nancy D Denslow

2009-01-01

255

Separating mixtures by exploiting molecular packing effects in microporous materials.  

PubMed

We examine mixture separations with microporous adsorbents such as zeolites, metal-organic frameworks (MOFs) and zeolitic imidazolate frameworks (ZIFs), operating under conditions close to pore saturation. Pore saturation is realized, for example, when separating bulk liquid phase mixtures of polar compounds such as water, alcohols and ketones. For the operating conditions used in industrial practice, pore saturation is also attained in separations of hydrocarbon mixtures such as xylene isomers and hexane isomers. Separations under pore saturation conditions are strongly influenced by differences in the saturation capacities of the constituent species; the adsorption is often in favor of the component with the higher saturation capacity. Effective separations are achieved by exploiting differences in the efficiency with which molecules pack within the ordered crystalline porous materials. For mixtures of chain alcohols, the shorter alcohol can be preferentially adsorbed because of its higher saturation capacity. With hydrophilic adsorbents, water can be selectively adsorbed from water-alcohol mixtures. For separations of o-xylene-m-xylene-p-xylene mixtures, the pore dimensions of MOFs can be tailored in such a manner as to allow optimal packing of the isomer that needs to be adsorbed preferentially. Subtle configurational differences between linear and branched alkane isomers result in significantly different packing efficiencies within the pore topology of MFI, AFI, ATS, and CFI zeolites. A common characteristic feature of most separations that are reliant on molecular packing effects is that adsorption and intra-crystalline diffusion are synergistic; this enhances the separation efficiencies in fixed bed adsorbers. PMID:25377790

Krishna, Rajamani

2015-01-01

256

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

Microsoft Academic Search

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

T. Baars

2002-01-01

257

Two stage carbon dioxide and methane (ethane) separation  

Microsoft Academic Search

A mixture of carbon dioxide (COâ) and ethane derived from a prior separation stage or recovery process is separated in 2 distillation columns. A first distillation of a COâ-ethane mixture forms an ethane-COâ azeotrope at a first pressure. The azeotropic mixture then is transferred to a second distillation column operated at a different pressure. The pressure difference between the 2

Styring; R. E. Jr

1982-01-01

258

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

DOEpatents

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

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

2011-01-04

259

Gene Expression Responses in Male Fathead Minnows Exposed to Binary Mixtures of an Estrogen and Antiestrogen  

EPA Science Inventory

Aquatic organisms are continuously exposed to complex mixtures of chemicals, many of which can interfere with their endocrine system, resulting in impaired reproduction, development or survival, among others. In order to analyze the effects and mechanisms of action of estrogen...

260

PREDICTION OF THE SOLUBILITY OF HYDROPHOBIC COMPOUNDS IN NONIDEAL SOLVENT MIXTURES  

EPA Science Inventory

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

261

PREDICTION OF THE SOLUBILITY OF HYDROPHOBIC COMPOUNDS IN NONIDEAL SOLVENT MIXTURES  

EPA Science Inventory

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

262

Olfactory discrimination of complex mixtures of amino acids by the black bullhead Ameiurus melas.  

PubMed

On the basis of previous findings of behavioural discrimination of amino acids and on the knowledge of electrophysiology of the catfish (genera Ictalurus and Ameiurus) olfactory organs, behavioural experiments that investigated olfactory discrimination of amino acid mixtures were carried out on the black bullhead Ameiurus melas. Repeated presentations of food-rewarded mixtures released increased swimming activity measured by counting the number of turns >90° within 90 s of stimulus addition. Non-rewarded amino acids and their mixtures released little swimming activity, indicating that A. melas discriminated between the conditioned and the non-conditioned stimuli. Two questions of mixture discrimination were addressed: (1) Are A. melas able to detect components within simple and complex amino acid mixtures? (2) What are the smallest differences between two complex mixtures that A. melas can detect? Three and 13 component mixtures tested were composed primarily of equipotent amino acids [determined by equal electroolfactogram (EOG) amplitude] that contained L-Cys at ×100 the equipotent concentration. Ameiurus melas initially perceived the ternary amino acid mixture as its more stimulatory component alone [i.e. cysteine (Cys)], whereas the conditioned 13 component mixture containing the more stimulatory L-Cys was perceived immediately as different from L-Cys alone. The results indicate that components of ternary mixtures are detectable by A. melas but not those of more complex mixtures. To test for the smallest detectable differences in composition between similar multimixtures, all mixture components were equipotent. Initially, A. melas were unable to discriminate the mixtures of six amino acids from the conditioned mixtures of seven amino acids, whereas they discriminated immediately the mixtures of four and five amino acids from the conditioned mixture. Experience with dissimilar mixtures enabled the A. melas to start discriminating the seven-component conditioned mixture from its six-component counterparts. After fewer than five training trials, A. melas discriminated the mixtures of nine and 10 amino acids from a conditioned mixture of 12 equipotent amino acids; however, irrespective of the number of training trials, A. melas were unable to discriminate the 12 component mixture from its 11 component counterparts. PMID:21722109

Valentincic, T; Miklavc, P; Kralj, S; Zgonik, V

2011-07-01

263

Organic waste disposal system  

Microsoft Academic Search

Organic waste material is pneumatically transported within air and mixed therewith by swirling flow through an annular ejector passage of varying radial width into a reaction flow passage of an eductor nozzle section receiving the output plume of a plasma torch for initiating therein thermal gasification of the waste mixture. The plasma torch plume projects from the eductor section into

E. E. Nolting; J. Colfield; R. Richard; S. Peterson

1997-01-01

264

Tutorial on mixture models (2) Christian Hennig  

E-print Network

Tutorial on mixture models (2) Christian Hennig September 2, 2009 Christian Hennig Tutorial-means and the fixed partition model Agglomerative hierarchical methods Christian Hennig Tutorial on mixture models (2 effects Mixtures of generalised linear models Christian Hennig Tutorial on mixture models (2) #12;Guide

Hennig, Christian

265

Bayesian Kernel Mixtures for Counts.  

PubMed

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

Canale, Antonio; Dunson, David B

2011-12-01

266

Blind Identification of Overcomplete MixturEs of sources (BIOME)  

Microsoft Academic Search

The problem of Blind Identification of linear mixtures of independent random processes is known to be related to the diagonalization of some tensors. This problem is posed here in terms of a non-conventional joint approximate diagonalization of several matrices. In fact, a congruent transform is applied to each of these matrices, the left transform being rectangular full rank, and the

Laurent Albera; Anne Ferréol; Pierre Comon; Pascal Chevalier

2004-01-01

267

Unrestricted Mixture Models for Class Identification in Growth Mixture Modeling  

ERIC Educational Resources Information Center

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…

Liu, Min; Hancock, Gregory R.

2014-01-01

268

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

PubMed Central

In this article, we highlight new developments and recent studies concerning adverse human health effects related to chemical mixtures. One group of activities comprises the development of a new computer program for analyzing mixture studies and a mathematical model as a basis for combination rules that predict the toxicity of mixtures. Other new activities in the area of experimental studies are the application of gene expression technologies in mixture research, and pattern recognition as a tool in safety evaluation of complex mixtures. A "bottom-up" approach for chemosensory detection of mixtures has recently been presented. Other topics include a method for the safety evaluation of natural flavoring complexes, and an evaluation of the possible health effects of the simultaneous intake of food additives. Examples of issues related to mixtures of airborne chemicals are potential interaction of fine particles and gaseous pollutants in ambient air, nasal cancer associated with inhaled chemical mixtures, and the recommendation of a limit value for volatile organic compounds. Topics of a more strategic nature include studies concerning the public health effects of large airports, and the development of criteria for a harmonized classification of chemical mixtures. This overview illustrates that strategies to tackle the safety evaluation of combined exposures and complex mixtures as well as models facilitating the interpretation of findings in the context of risk assessment of mixtures have become increasingly important. It is true that exposure of humans to chemical mixtures is the rule rather than the exception, and therefore health risk assessments should focus on mixtures and not on single chemicals. It is also true, however, that humans have learned to cope with exposure to huge numbers of chemicals simultaneously (food, water, air, soil, and consumer products). Therefore, in view of limited resources for toxicological research, the focus in toxicology should be on priority mixtures--priority being determined by (estimated) health risk (= toxicity and exposure). PMID:12634116

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

2002-01-01

269

Simultaneous De Novo Identification of Molecules in Chemical Mixtures by Doubly Indirect Covariance NMR Spectroscopy  

PubMed Central

The detailed characterization of complex molecular mixtures plays a key role in many areas of modern Chemistry. Here we report a novel NMR spectroscopic method that deconvolutes a complex mixture of organic molecules simultaneously into individual components and depicts their chemical structure without requiring physical separation of the components. Doubly indirect covariance spectroscopy is introduced and applied to 2D 13C-1H HSQC and 2D 1H-1H COSY spectra, which results in a 13C-13C 2D spectrum with unprecedented high resolution. This reconstituted spectrum is indeed a carbon-connectivity map that can be directly analyzed with basic graph theory to obtain the skeletal structures of individual mixture components or their fragments. The method is demonstrated for a model mixture and a natural product mixture extracted from cancer cells. Its suitability for automation makes this approach attractive for the analysis of a broad range of mixtures of natural or synthetic products. PMID:21062057

Zhang, Fengli; Bruschweiler-Li, Lei; Brüschweiler, Rafael

2010-01-01

270

Mixture Segregation within Sonoluminescence Bubbles  

Microsoft Academic Search

This paper concerns a relaxation of the assumption of uniform mixture composition in the interior of sonoluminescence bubbles. Intense temperature and pressure gradients within the bubble drive relative mass diffusion which overwhelms diffusion driven by concentration gradients. This thermal and pressure diffusion results in a robust compositional inhomogeneity in the bubble which lasts several orders of magnitude longer than the

Brian D. Storey; Andrew J. Szeri

1999-01-01

271

Bayesian Hierarchical Mixtures of Experts  

Microsoft Academic Search

The Hierarchical Mixture of Experts (HME) is a well-known tree-structured model for regres- sion and classification, based on soft probabilis- tic splits of the input space. In its original for- mulation its parameters are determined by maxi- mum likelihood, which is prone to severe over- fitting, including singularities in the likelihood function. Furthermore the maximum likelihood framework offers no natural

Christopher M. Bishop; Markus Svensén

2003-01-01

272

Mixtures of (Constrained) Ultrametric Trees.  

ERIC Educational Resources Information Center

Presents a method for the estimation of ultrametric trees calibrated on subjects' pairwise proximity judgments of stimuli, capturing subject heterogeneity using a finite mixture formulation. An empirical example from published data shows the ability to deal with external constraints on the tree topology. (Author/SLD)

Wedel, Michel; DeSarbo, Wayne S.

1998-01-01

273

Weakly interacting colloid polymer mixtures  

NASA Astrophysics Data System (ADS)

This thesis explores the physics of weakly interacting colloid-polymer mixtures. Colloid-polymer mixtures can consist of two kinds of interactions; depletion and adsorption. Both interactions can lead to colloidal aggregation and formation of space spanning gels that can bear stress. Depending on the range of the attractive interaction, depletion gels bear stress by two mechanisms; bond-stretching and bond-bending. Gels formed with long-range interactions bear stress by bond-stretching while gels formed with short-range interactions bear stress by bond-bending. Rheological measurements of the elastic plateau modulus G'p and confocal microscopy measurements of the response of the gel to thermal fluctuations support this hypothesis. The phase behavior of the depletion aggregates is also profoundly influenced by the range of the interaction potential. A simple kinetic model that compares time scales of aggregation and bond break-up quantitatively explains the phase behavior for different ranges of the interaction potential. For the case of adsorption, the equilibrium phase of the colloid polymer mixture at rest is that of a Newtonian fluid. However, for certain ratios of colloid and polymer, the system can form a gel on application of shear. The gels that are formed are transient in nature, and revert back to the fluid state over a time scale of minutes to days. We find that the colloid polymer mixtures form "shake-gels" when the surface of the colloid is unsaturated with polymer. Shear causes the polymer to elongate and bridge between different colloidal particles, forming aggregates that eventually span space. When the polymer completely coats the surface of the particles, there is no longer shear-induced gelation as the polymer acts like a steric barrier. Therefore, we conclude that changing the polymer dimensions has a profound influence on the bulk properties of the colloidal aggregates that are formed in colloid-polymer mixtures.

Prasad, Vikram

274

Combined toxicity of pesticide mixtures on green algae and photobacteria.  

PubMed

Different organisms have diverse responses to the same chemicals or mixtures. In this paper, we selected the green algae Chlorella pyrenoidosa (C. pyrenoidosa) and photobacteria Vibrio qinghaiensis sp.-Q67 (V. qinghaiensis) as target organisms and determined the toxicities of six pesticides, including three herbicides (simetryn, bromacil and hexazinone), two fungicides (dodine and metalaxyl) and one insecticide (propoxur), and their mixtures by using the microplate toxicity analysis. The toxicities of three herbicides to C. pyrenoidosa are much higher than those to V. qinghaiensis, and the toxicities of metalaxyl and propoxur to V. qinghaiensis are higher than those to C. pyrenoidosa, while the toxicity of dodine to C. pyrenoidosa is similar to those to V. qinghaiensis. Using the concentration addition as an additive reference model, the binary pesticide mixtures exhibited different toxicity interactions, i.e., displayed antagonism to C. pyrenoidosa but synergism to V. qinghaiensis. However, the toxicities of the multi-component mixtures of more than two components are additive and can be predicted by the concentration addition model. PMID:23816361

Liu, Shu-Shen; Wang, Cheng-Lin; Zhang, Jin; Zhu, Xiang-Wei; Li, Wei-Ying

2013-09-01

275

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

Microsoft Academic Search

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

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

1998-01-01

276

Plasma polymerization of an ethylene-nitrogen gas mixture  

NASA Technical Reports Server (NTRS)

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

Hudis, M.; Wydeven, T.

1975-01-01

277

DESIGNING FIXED-BED ADSORBERS TO REMOVE MIXTURES OF ORGANICS  

EPA Science Inventory

A liquid-phase granular activated carbon (GAC) pilot plant and a full-scale GAG adsorber were designed, built, and operated in order to evaluate their performance for treating a groundwater contaminated with several volatile and synthetic organicchemicals. everal empty bed contac...

278

Separation and IR Analysis of a Mixture of Organic Compounds.  

ERIC Educational Resources Information Center

Presents an experiment which includes fractional distillation with gas-liquid chromatography (GLC) and infrared analysis. Objectives are to introduce students to fractional distillation and analysis of each fraction by GLC, to induce them to decide if each fraction is sufficient for infrared analysis, and to identify unknowns. (Author/JN)

Thompson, Evan M.; Almy, John

1982-01-01

279

Analysis of Analgesic Mixtures: An Organic Chemistry Experiment.  

ERIC Educational Resources Information Center

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

Martin, Ned H.

1981-01-01

280

Mixtures  

NSDL National Science Digital Library

In this activity, students add balls, either colored or not, to two different piles then combine the piles to see the resulting percent of colored balls. Students can also change modes so that they must provide the right quantity of balls to make a resulting amount and percent. This activity allows students to explore percents and the idea of a weighted average. This activity includes supplemental materials, including background information about the topics covered, a description of how to use the application, and exploration questions for use with the java applet.

2010-01-01

281

Local fluctuations in solution mixtures  

PubMed Central

An extension of the traditional Kirkwood-Buff (KB) theory of solutions is outlined which provides additional fluctuating quantities that can be used to characterize and probe the behavior of solution mixtures. Particle-energy and energy-energy fluctuations for local regions of any multicomponent solution are expressed in terms of experimentally obtainable quantities, thereby supplementing the usual particle-particle fluctuations provided by the established KB inversion approach. The expressions are then used to analyze experimental data for pure water over a range of temperatures and pressures, a variety of pure liquids, and three binary solution mixtures – methanol and water, benzene and methanol, and aqueous sodium chloride. In addition to providing information on local properties of solutions it is argued that the particle-energy and energy-energy fluctuations can also be used to test and refine solute and solvent force fields for use in computer simulation studies. PMID:21806137

Ploetz, Elizabeth A.; Smith, Paul E.

2011-01-01

282

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...

283

Variable mixture ratio performance through nitrogen augmentation  

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

284

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

PubMed

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

Cowin, Stephen C; Cardoso, Luis

2012-01-01

285

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

PubMed Central

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

Cowin, Stephen C.; Cardoso, Luis

2011-01-01

286

Improved Stability of Solid Mixture Nanoparticles  

E-print Network

to be synthesized in the future #12;Block Copolymer Stabilized Solid Mixtures Nanoparticles Ibuprofen + Retinoic Pure active, inert Physical mixture #12;Ibuprofen Retinoic Acid Needle Crystal Structure Powder #12;Ibuprofen Retinoic Acid Mixture Precipitated Ibuprofen, Dialyzed Precipitated Retinoic Acid, Dialyzed #12

Petta, Jason

287

SOLVENT EXTRACTION OF ORGANIC WATER POLLUTANTS  

EPA Science Inventory

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

288

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

PubMed

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

Abdullah, N; Chin, N L

2010-11-01

289

Method of photocatalytic conversion of C-H organics  

DOEpatents

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

Camaioni, Donald M. (Richland, WA); Lilga, Michael A. (Richland, WA)

1998-01-01

290

Method of photocatalytic conversion of C-H organics  

DOEpatents

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

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

1998-01-13

291

Application of Solvents Mixtures Based on Tributylphosphate for Selective Extraction-Sorption Concentrating of Phenol and Guayacol  

Microsoft Academic Search

The influence of polysorb on the quantitative characteristics of stationary extraction for phenol and guayacol with mixtures of tributylphosphate (TBP) and organic solvents of different classes (distribution coefficients, synergecity) was studied. Solvation numbers and constants of entering of TBP into mixed solvates were calculated both for extraction and extraction-sorption systems. Comparative study of selectivity for a mixture of extracting agents

Ya. I. Korenman; A. T. Alymova; I. V. Vatutina

2000-01-01

292

EXPERIMENTAL AND MODELING STUDY OF THE AUTOIGNITION OF 1-HEXENE / ISO-OCTANE MIXTURES AT LOW TEMPERATURE  

E-print Network

]. The effect of the addition of toluene to the oxidation of alkanes has been investigated in the case of n classes of organic compounds. The major part of the studies published on mixture oxidation concerns for its oxidation have been proposed [1, 3, 4]. In the case of paraffin/ether mixtures, the autoignition

Paris-Sud XI, Université de

293

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

PubMed Central

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

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

2002-01-01

294

Effect of Cement on Emulsified Asphalt Mixtures  

NASA Astrophysics Data System (ADS)

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.

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

2007-10-01

295

Solidification of a binary mixture  

NASA Technical Reports Server (NTRS)

The time dependent concentration and temperature profiles of a finite layer of a binary mixture are investigated during solidification. The coupled time dependent Stefan problem is solved numerically using an implicit finite differencing algorithm with the method of lines. Specifically, the temporal operator is approximated via an implicit finite difference operator resulting in a coupled set of ordinary differential equations for the spatial distribution of the temperature and concentration for each time. Since the resulting differential equations set form a boundary value problem with matching conditions at an unknown spatial point, the method of invariant imbedding is used for its solution.

Antar, B. N.

1982-01-01

296

Organic waste disposal system  

SciTech Connect

Organic waste material is pneumatically transported within air and mixed therewith by swirling flow through an annular ejector passage of varying radial width into a reaction flow passage of an eductor nozzle section receiving the output plume of a plasma torch for initiating therein thermal gasification of the waste mixture. The plasma torch plume projects from the eductor section into a diffuser section within which thermal gasification is continued before discharge of gasified waste.

Nolting, E.E.; Colfield, J.; Richard, R.; Peterson, S.

1997-12-31

297

Supercritical Water Mixture (SCWM) Experiment  

NASA Technical Reports Server (NTRS)

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.

Hicks, Michael C.; Hegde, Uday G.

2012-01-01

298

Accelerated Hazards Mixture Cure Model  

PubMed Central

We propose a new cure model for survival data with a surviving or cure fraction. The new model is a mixture cure model where the covariate effects on the proportion of cure and the distribution of the failure time of uncured patients are separately modeled. Unlike the existing mixture cure models, the new model allows covariate effects on the failure time distribution of uncured patients to be negligible at time zero and to increase as time goes by. Such a model is particularly useful in some cancer treatments when the treat effect increases gradually from zero, and the existing models usually cannot handle this situation properly. We develop a rank based semiparametric estimation method to obtain the maximum likelihood estimates of the parameters in the model. We compare it with existing models and methods via a simulation study, and apply the model to a breast cancer data set. The numerical studies show that the new model provides a useful addition to the cure model literature. PMID:19697127

Zhang, Jiajia; Peng, Yingwei

2010-01-01

299

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

EPA Science Inventory

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

300

Sludge organics bioavailability  

SciTech Connect

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

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

1991-01-01

301

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

SciTech Connect

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

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

1992-04-01

302

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

SciTech Connect

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

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

1992-04-01

303

Mixture distributions in human genetics research.  

PubMed

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

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

1996-06-01

304

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

SciTech Connect

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

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

2009-05-01

305

Two stage carbon dioxide and methane (ethane) separation  

SciTech Connect

A mixture of carbon dioxide (CO/sub 2/) and ethane derived from a prior separation stage or recovery process is separated in 2 distillation columns. A first distillation of a CO/sub 2/-ethane mixture forms an ethane-CO/sub 2/ azeotrope at a first pressure. The azeotropic mixture then is transferred to a second distillation column operated at a different pressure. The pressure difference between the 2 columns is at least 150 psi and is sufficient to allow further distillation of the azeotrope so that additional separation is obtained. The relative concentrations of CO/sub 2/ and ethane in an azeotropic mixture depend on the pressure at which the azeotrope was formed. Increasing the distillation pressure causes the azeotrope point to move toward the right side of a phase diagram. Decreasing the distillation pressure causes the azeotrope point to move to the left. When the concentration of CO/sub 2/ in the original ethane-CO/sub 2/ mixture is less than the concentration of CO/sub 2/ in the azeotropic mixture formed in the first distillation column, preferably the pressure in the second stage distillation column will be at least 150 psi less than the pressure in the first stage distillation column and vice versa. 3 claims. (Also related to U.S. 12/28/79 (Appl. 108,204))

Styring, R.E.Jr

1982-09-28

306

Decompression in diving with gas mixtures (J. Riba) 1/22 Decompression in diving with gas mixtures  

E-print Network

Decompression in diving with gas mixtures (J. Riba) 1/22 Decompression in diving with gas mixtures;Decompression in diving with gas mixtures (J. Riba) 2/22 ÍNDICE Acronims..............................................................................5 2.2 Decompression mixtures

Riba Sagarra, Jaume

307

Gas Separation Using Organic-Vapor-Resistent Membranes In Conjunctin With Organic-Vapor-Selective Membranes  

Microsoft Academic Search

A process for treating a gas mixture containing at least an organic compound gas or vapor and a second gas, such as natural gas, refinery off-gas or air. The process uses two sequential membrane separation steps, one using membrane selective for the organic compound over the second gas, the other selective for the second gas over the organic vapor. The

Richard W. Baker; Ingo Pinnau; Zhenjie He; Andre R. Da Costa; Ramin Daniels; Karl D. Amo; Johannes G. Wijmans

2003-01-01

308

Separating Mixtures: How We Concentrate Natural Materials  

NSDL National Science Digital Library

This activity involves separating mixtures of minerals on the basis of their physical properties. Students are shown a piece of granite and see that it is clearly a mixture. Students will try to devise ways of separating some simple mixtures and then see how some of the same methods are used to separate real minerals from mixtures. Students will discover that many useful materials are found as part of mixtures. For example, salt is found in underground deposits mixed with sand and clay. The mixture is called rock salt. Minerals are chemicals found naturally in the Earth and many of them are very useful. To get at the useful minerals, we usually have to separate them from less-useful material which are often called gangue (pronounced gang) by miners.

309

Engineering preliminaries to obtain reproducible mixtures of atelocollagen and polysaccharides.  

PubMed

The critical stage in producing blends of biomacromolecules consists in the mixing of component solutions to generate homogenous diluted colloidal systems. Simple experimental investigations allow the establishment of the design rules of recipes and the procedures for preparing homogenous and compositionally reproducible mixtures. Starting from purified solutions of atelocollagen, hyaluronan and native gellan, having as low as possible inorganic salts content, initial binary and ternary mixtures can be prepared up to a total dry matter content of 0.150 g/dL, in no co-precipitating conditions. Two pH manipulation ways are feasible for homogenous mixing: (i) unbuffered prior correction at pH 5.5, and (ii) "rigid" buffering at pH 9.0, using organic species. Atelocollagen including co-precipitates can be obtained in the presence of one or both polysaccharides, preferably in pH domains far from the isoelectric point of scleroprotein. A critical behavior has been observed in mixtures containing gellan, due to its macromolecular dissimilarities compared with atelocollagen. In optimal binary mixtures, the coordinates of threshold points on the phase diagrams are 0.028% w/w atelocollagen/0.025% w/w hyaluronan, and 0.022% w/w atelocollagen/0.020% w/w gellan. Uni- or bi-phasic ternary systems having equilibrated ratios of co-precipitated components can be prepared starting from initial mixtures containing up to 0.032 g/dL atelocollagen, associated with, for example, 0.040 g/dL hyaluronan and 0.008 g/dL gellan, following the first pH manipulation way. PMID:23498265

Lefter, Cristina-Mihaela; Maier, Stelian Sergiu; Maier, Vasilica; Popa, Marcel; Desbrieres, Jacques

2013-05-01

310

Organic synthesis in experimental impact shocks.  

PubMed

Laboratory simulations of shocks created with a high-energy laser demonstrate that the efficacy of organic production depends on the molecular, not just the elemental composition of the shocked gas. In a methane-rich mixture that simulates a low-temperature equilibrium mixture of cometary material, hydrogen cyanide and acetylene were produced with yields of 5 x 10(17) molecules per joule. Repeated shocking of the methane-rich mixture produced amine groups, suggesting the possible synthesis of amino acids. No organic molecules were produced in a carbon dioxide-rich mixture, which is at odds with thermodynamic equilibrium approaches to shock chemistry and has implications for the modeling of shock-produced organic molecules on early Earth. PMID:9103191

McKay, C P; Borucki, W J

1997-04-18

311

Organic synthesis in experimental impact shocks  

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

312

Performance-based asphalt mixture design methodology  

NASA Astrophysics Data System (ADS)

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 performance based design procedure. Finally, the developed guidelines with easy-to-use flow charts for the integrated mix design methodology are presented.

Ali, Al-Hosain Mansour

313

Metal Mixtures Modeling Evaluation project: 1. Background.  

PubMed

Despite more than 5 decades of aquatic toxicity tests conducted with metal mixtures, there is still a need to understand how metals interact in mixtures and to predict their toxicity more accurately than what is currently done. The present study provides a background for understanding the terminology, regulatory framework, qualitative and quantitative concepts, experimental approaches, and visualization and data-analysis methods for chemical mixtures, with an emphasis on bioavailability and metal-metal interactions in mixtures of waterborne metals. In addition, a Monte Carlo-type randomization statistical approach to test for nonadditive toxicity is presented, and an example with a binary-metal toxicity data set demonstrates the challenge involved in inferring statistically significant nonadditive toxicity. This background sets the stage for the toxicity results, data analyses, and bioavailability models related to metal mixtures that are described in the remaining articles in this special section from the Metal Mixture Modeling Evaluation project and workshop. It is concluded that although qualitative terminology such as additive and nonadditive toxicity can be useful to convey general concepts, failure to expand beyond that limited perspective could impede progress in understanding and predicting metal mixture toxicity. Instead of focusing on whether a given metal mixture causes additive or nonadditive toxicity, effort should be directed to develop models that can accurately predict the toxicity of metal mixtures. Environ Toxicol Chem 2015;34:726-740. © 2014 SETAC. PMID:25353683

Meyer, Joseph S; Farley, Kevin J; Garman, Emily R

2015-04-01

314

DETERMINATION AND QUANTIFICATION OF NON-AQUEOUS PHASE LIQUID MIXTURES IN ENVIRONMENTAL MEDIA  

SciTech Connect

It is important to recognize the presence of Non-Aqueous Phase Liquids (NAPLs) in soils at a waste site in order to design and construct a successful remediation system. NAPLs often manifest as a complex, multi-component mixture of organic compounds that can occur in environmental media, such as vadose zone soil, where the mixture will partition and equilibrate with soil particles, pore vapor, and pore water. Complex organic mixtures can greatly complicate the determination and quantification of NAPL in soil due to inter-media transfer. NAPL thresholds can also change because of mixture physical properties and can disguise the presence of NAPL. A unique analytical method and copyrighted software have been developed at the Department of Energy's Savannah River Site that facilitates solution of this problem. The analytical method uses a classic chemistry approach and applies the principals of solubility limit theory, Raoult's Law, and equilibrium chemistry to derive an accurate estimation of NAPL presence and quantity. The method is unique because it calculates an exact result that is mass balanced for each physical state, chemical mixture component, and mixture characteristics. The method is also unique because the solution can be calculated on both a wet weight and dry weight basis--a factor which is often overlooked. The software includes physical parameters for 300 chemicals in a database that self-loads into the model to save time. The method accommodates up to 20 different chemicals in a multi-component mixture analysis. A robust data display is generated including important parameters of the components and mixture including: NAPL thresholds for individual chemical components within the mixture, mass distribution in soil for each physical state, molar fractions, density, vapor pressure, solubility, mass balance, media concentrations, residual saturation, and modest graphing capabilities. This method and software are power tools to simplify otherwise tedious calculations and eliminate guesswork for site characterizations.

Rucker, G

2006-09-22

315

COMPLEX MIXTURES AND GROUND WATER QUALITY  

EPA Science Inventory

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

316

Analysis of Ultrasonic Velocities in Hydrocarbon Mixtures  

E-print Network

Analysis of Ultrasonic Velocities in Hydrocarbon Mixtures James G. Berryman Lawrence Livermore National Laboratory P. O. Box 808 L­202 Livermore, CA 94551­9900 #12; Abstract Ultrasonic velocity data of measurements on ultrasonic velocities of liquid hydrocarbons and mixtures. They found that their data

317

Method for separating isotopes from gaseous mixtures  

Microsoft Academic Search

To separate isotopes from a gaseous mixture containing isotopes and a chemical reaction partner, the reaction between the partner and the isotope to be separated can be directed by a laser beam having a narrow band of wavelengths molecularly exciting the isotope to be separated. To maximize such an effect, the gaseous mixture is held inside of a laser cavity

H. J. Niemann; E. Schuster; A. Kersting

1978-01-01

318

Method of separating isotopes from gaseous mixtures  

Microsoft Academic Search

Separation of isotopes from a gaseous mixture of substances containing the isotopes by incorporating supplemental gas and adiabatically expanding at an expansion ratio and starting temperature to cool the mixture and effect condensation of at least a portion of the supplemental gas. Laser radiation is applied to effect selective excitation of one isotope component with selective retention of the non-excited

K. Gregorius; K. Janner; A. Kersting; H. Niemann; E. Schuster

1982-01-01

319

Efficient Separation of Convolutive Image Mixtures  

Microsoft Academic Search

Convolutive mixtures of images are common in photography of semi-reflections. They also occur in microscopy and tomography. Their formation process involves focusing on an object layer, over which defo- cused layers are superimposed. Blind source separation (BSS) of convolu- tive image mixtures by direct optimization of mutual information is very complex and suffers from local minima. Thus, we devise an

Sarit Shwartz; Yoav Y. Schechner; Michael Zibulevsky

2006-01-01

320

Gas mixtures for spark gap closing switches  

DOEpatents

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.

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

1987-02-20

321

Probabilistic expert systems for DNA mixture profiling  

Microsoft Academic Search

We show how probabilistic expert systems can be used to structure and solve complex cases of forensic identification involving DNA traces that might be mixtures of several DNA profiles. In particular, this approach can readily handle cases where the number of contributors to the mixture cannot be regarded as known in advance. The flexible modularity of the networks used also

J. Mortera; A. P. Dawid; S. L. Lauritzen

2003-01-01

322

Mixture product design using latent variable methods  

Microsoft Academic Search

This thesis investigates the use of latent variable methods for the analysis, design and optimization of mixture processes. These strategies simultaneously take into account the selection of raw materials, the selection of the ratios in which to blend them and the selection of process conditions used to manufacture them. ^ The thesis consists of five main chapters: (i) mixture-property PLS

Koji Muteki

2006-01-01

323

Laser kinetic processes in dye mixtures  

SciTech Connect

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.

Lei Jie; Fu Honglang

1988-11-01

324

Process Dissociation and Mixture Signal Detection Theory  

ERIC Educational Resources Information Center

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

DeCarlo, Lawrence T.

2008-01-01

325

Separation of gas mixtures by centrifugation  

NASA Technical Reports Server (NTRS)

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.

Park, C.; Love, W. L.

1972-01-01

326

Transport coefficients of multicomponent gas mixtures  

Microsoft Academic Search

General expressions for the transport coefficients of multicomponent gas mixture have been written in a form where the computations for a given N-component gas mixture and for any order can be done on the computer without feeding the explicit expressions for the matrix elements. (General expressions, available in literature earlier, require seperate computer programs for each order of calculation.) These

Kuldip Singh; A. K. Dham; S. C. Gupta

1989-01-01

327

Diffusion method of seperating gaseous mixtures  

Microsoft Academic Search

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

Rex B

1976-01-01

328

PATTERN CLUSTERING BY MULTIVARIATE MIXTURE ANALYSIS  

Microsoft Academic Search

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

JOHN H. WOLFE

1970-01-01

329

The Potential of Growth Mixture Modelling  

ERIC Educational Resources Information Center

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…

Muthen, Bengt

2006-01-01

330

Gaussian Mixture Models Introducing Latent Variables  

E-print Network

Sampling from the GMM To sample from the GMM, we can first generate a value for z from the marginal #12;Gaussian Mixture Models Sampling Sampling from the GMM To sample from the GMM, we can first;Gaussian Mixture Models Sampling Sampling from the GMM To sample from the GMM, we can first generate

Corso, Jason J.

331

Size-dependent assemblies of nanoparticle mixtures in thin films.  

PubMed

Hybrid nanoparticle (NP) arrays based on particles of different sizes and chemistries are highly desirable to obtain tunable properties for nanodevices. A simple approach to control the spatial organization of NP mixtures within supramolecular frameworks based on NP size has been developed. By varying the ratio of the NP size to the periodicity of the block-copolymer-based supramolecule, a range of hybrid NP assemblies in thin films, ranging from 1D chains to 2D lattices and 3D arrays and networks of NPs, can be readily generated. PMID:23327718

Kao, Joseph; Bai, Peter; Lucas, J Matthew; Alivisatos, A Paul; Xu, Ting

2013-02-01

332

Environmental quality standards for mixtures: a case study with a herbicide mixture tested in outdoor mesocosms.  

PubMed

Traces of pesticides are frequently detected in surface waters. As a consequence, specific environmental quality criteria (EQS) for a set of single pesticides in surface waters were defined by the environmental authorities in several countries. In this context, the aim of this study was to investigate if the sum of the five percentile hazard concentration (?HC(5-95 percent), meaning that 5 percent of the aquatic assemblage remains affected considering a 95 percent confidence interval) of three herbicides with the same mode of action derived from a species sensitivity distribution based on acute toxicity data (EC(50) values) of the most sensitive taxonomic group is a suitable EQS for surface water addressing the occurrence of herbicide mixtures as common exposure scenario. Therefore, an outdoor mesocosm study was performed with three replicates per treatment for a period of 173 days. Results demonstrated that a constant long-term exposure over 35 days to the HC(5-95 percent) of a mixture of three PSII inhibitors did not lead to adverse effects on the aquatic community in this field mesocosm study. Neither adverse effects on very sensitive functional endpoints such as photosynthesis measurements of algae and macrophytes nor adverse effects on structural endpoints such as abundance data and species composition were determined. In contrast and as a positive control, the HC(30) treatment affected statistically significant all investigated endpoints and it was demonstrated that the PSII inhibitors acted additive on various level of organization (Knauert et al., 2008). This study is filling the gap that no empirical evidence is published indicating that the chronic exposure at the HC(5-95 percent) estimate is leading to no adverse effects for the aquatic community and is therefore a suitable EQS for surface waters in the agriculture landscape. PMID:23273621

Knauer, Katja; Hommen, Udo

2013-03-01

333

Thermodiffusion Coefficient for Binary Liquid Hydrocarbon Mixtures  

NASA Astrophysics Data System (ADS)

In this work, the thermogravitational technique has been used to determine the thermodiffusion coefficient of 18 binary mixtures of normal alkanes formed with the n-octadecane as the densest component and mixed with normal alkanes from n-pentane to n-tridecane in two series of experimental tests (nine binary mixtures with mass fraction c = 0.5 and nine binary mixtures with molar fraction x = 0.5 in each component for each mixture). The measurement of the steady separation of these mixtures in the thermogravitational column, as well as their corresponding thermophysical properties, has been determined at the average temperature of 25°C. The main result shows a linear dependency of the thermodiffusion coefficient on the relative density difference, and this in both series of experimental tests (mass and molar fraction equal to 0.5).

Blanco, P.; Bou-Ali, M. M.; Platten, J. K.; Madariaga, J. A.; Urteaga, P.; Santamaría, C.

2007-09-01

334

Mixing - Simulating Mixture Problems with Beads  

NSDL National Science Digital Library

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

2011-01-01

335

Relativistic mixtures of charged and uncharged particles  

NASA Astrophysics Data System (ADS)

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.

Kremer, Gilberto M.

2014-01-01

336

Prediction of viscosity of dense fluid mixtures  

NASA Astrophysics Data System (ADS)

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.

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

337

Picosecond reorientational dynamics of polar dye probes in binary aqueous mixtures  

NASA Astrophysics Data System (ADS)

Picosecond time dependent fluorescence method has been used to measure the rotational reorientation times (?r) of three kinds of dye probes—oxazine 720 (a monocation), nile red (neutral but polar), and resorufin (a monoanion)—in a series of binary mixtures of water-amides, water-dipolar aprotics, and water-alcohols at 298 K. Most of the binary mixtures are characterized by the fact that at a particular composition (between 25% to 40% of the organic solvent in water), the viscosity (?) of the solution reaches a maximum value that is higher than the viscosities of the two solvents. As a consequence, the viscosity profile of the solution as a function of the organic solvent exhibits a bivaluedness, the extent of which is more, if the liquids are nearly isoviscous. The dielectric properties of the solution also change across the composition range. All the dyes show a near linear behavior of ?r vs ? in formamide-water, N-methylformamide-water, and methanol-water mixtures. A dual-valued profile for ?r vs ? is obtained for the cation oxazine 720 in the three dipolar aprotic mixtures (N, N-dimethylformamide-water, N, N-dimethylacetamide-water, and dimethylsulphoxide-water), with the rotational reorientation times being higher in the organic solvent-rich zone, compared to the corresponding isoviscous point in the water-rich zone. However, the anion resorufin shows a bivalued profile of ?r vs ? only in dimethylsulphoxide-water mixtures, while the neutral nile red shows a linear behavior in all the dipolar-aprotic water mixtures. A hook-type profile of ?r vs ? is seen for the anion resorufin in ethanol-, 1-propanol-, and 2-propanol-water mixtures and for the cation oxazine 720 in 1-propanol- and 2-propanol-water mixtures; but nile red shows no departure from linear behavior even in alcohol-water mixtures. The rotational dynamics of the cation oxazine 720 in dipolar aprotic-water mixtures is explained in terms of solvation since the dielectric friction is minimal in these solutions. While the concept of dielectric friction model seems to be adequate to understand the nonhydrodynamic behavior of the oxazine 720, the additional contribution due to solvation effects has to be necessarily taken into account to explain the rotational dynamics of the anion resorufin in alcohol-water mixtures.

Dutt, G. B.; Doraiswamy, S.

1992-02-01

338

ODE Constrained Mixture Modelling: A Method for Unraveling Subpopulation Structures and Dynamics  

PubMed Central

Functional cell-to-cell variability is ubiquitous in multicellular organisms as well as bacterial populations. Even genetically identical cells of the same cell type can respond differently to identical stimuli. Methods have been developed to analyse heterogeneous populations, e.g., mixture models and stochastic population models. The available methods are, however, either incapable of simultaneously analysing different experimental conditions or are computationally demanding and difficult to apply. Furthermore, they do not account for biological information available in the literature. To overcome disadvantages of existing methods, we combine mixture models and ordinary differential equation (ODE) models. The ODE models provide a mechanistic description of the underlying processes while mixture models provide an easy way to capture variability. In a simulation study, we show that the class of ODE constrained mixture models can unravel the subpopulation structure and determine the sources of cell-to-cell variability. In addition, the method provides reliable estimates for kinetic rates and subpopulation characteristics. We use ODE constrained mixture modelling to study NGF-induced Erk1/2 phosphorylation in primary sensory neurones, a process relevant in inflammatory and neuropathic pain. We propose a mechanistic pathway model for this process and reconstructed static and dynamical subpopulation characteristics across experimental conditions. We validate the model predictions experimentally, which verifies the capabilities of ODE constrained mixture models. These results illustrate that ODE constrained mixture models can reveal novel mechanistic insights and possess a high sensitivity. PMID:24992156

Hasenauer, Jan; Hasenauer, Christine; Hucho, Tim; Theis, Fabian J.

2014-01-01

339

Ionic liquid/water mixtures: from hostility to conciliation.  

PubMed

Water was originally inimical to ionic liquids (ILs) especially in the analysis of their detailed properties. Various data on the properties of ILs indicate that there are two ways to design functions of ionic liquids. The first is to change the structure of component ions, to provide "task-specific ILs". The second is to mix ILs with other components, such as other ILs, organic solvents or water. Mixing makes it easy to control the properties of the solution. In this strategy, water is now a very important partner. Below, we summarise our recent results on the properties of IL/water mixtures. Stable phase separation is an effective method in some separation processes. Conversely, a dynamic phase change between a homogeneous mixture and separation of phases is important in many fields. Analysis of the relation between phase behaviour and the hydration state of the component ions indicates that the pattern of phase separation is governed by the hydrophilicity of the ions. Sufficiently hydrophilic ions yielded ILs that are miscible with water, and hydrophobic ions gave stable phase separation with water. ILs composed of hydrophobic but hydrated ions undergo a dynamic phase change between a homogeneous mixture and separate phases according to temperature. ILs having more than seven water molecules per ion pair undergo this phase transition. These dynamic phase changes are considered, with some examples, and application is made to the separation of water-soluble proteins. PMID:22683915

Kohno, Yuki; Ohno, Hiroyuki

2012-07-21

340

Genotoxicity of complex mixtures: CHO cell mutagenicity assay  

SciTech Connect

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

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

1985-02-01

341

Analysis and Control of Heteroazeotropic Batch Distillation  

E-print Network

Analysis and Control of Heteroazeotropic Batch Distillation S. Skouras and S. Skogestad Dept.interscience.wiley.com). The separation of close-boiling and azeotropic mixtures by heterogeneous azeotropic distillation is addressed. The results show that heteroazeotropic batch distillation exhibits substantial flexibility. The column profile

Skogestad, Sigurd

342

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

EPA Science Inventory

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

343

Environmental complex mixture toxicity assessment.  

PubMed

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. PMID:9860885

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

1998-12-01

344

Reproducibility of binary-mixture toxicity studies.  

PubMed

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

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

2007-01-01

345

Estrogenic activity of UV filter mixtures  

SciTech Connect

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.

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

2006-11-15

346

Viscosity of Mixtures of ?-Tocopherol Acetate + Mesitylene  

NASA Astrophysics Data System (ADS)

The paper presents results of the share viscosity measurements performed as a function of temperature and concentration for mixtures of ?-tocopherol acetate (vitamine E acetate) and mesitylene, two liquids of essentially different viscosity (four order of magnitude difference at 280 K). The viscosity/ temperature dependence for pure ?-tocopherol acetate as well as for the mixtures studied can be well described with the Vogel-Fulcher-Tammann equation. The viscosities of the mixtures exhibit a strong negative deviation from the rule of additive dependence on concentration and for increasing temperature the maximum value of the deviation shows an exponential decreasing.

Szwajczaka, El?bieta; Stagraczy?ski, Ryszard; Herba, Henryk; ?wiergielb, Jolanta; Jad?yn, Jan

2009-08-01

347

Biodegradation of chlorinated aliphatic hydrocarbon mixtures in a single-pass packed-bed reactor  

Microsoft Academic Search

Aliphatic chlorinated compounds, such as trichloroethylene (TCE) and tetrachloroethylene (PCE), are major contaminants of\\u000a ground water. A single-pass packed-bed bioreactor was utilized to study the biodegradation of organic waste mixtures consisting\\u000a of PCE, TCE, and other short-chain chlorinated organics. The bioreactor consisted of two 1960-mL glass columns joined in a\\u000a series. One column was packed with sand containing a microbial

L. W. Lackey; T. J. Phelps; P. R. Bienkowski; D. C. White

1993-01-01

348

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

NASA Technical Reports Server (NTRS)

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

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

1969-01-01

349

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

Microsoft Academic Search

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

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

2011-01-01

350

Production of microspheres of thorium oxide, uranium oxide and plutonium oxide and their mixtures containing carbon  

Microsoft Academic Search

A process is desclosed for the production of microspheres of thorium oxide, uranium oxide or plutonium oxide and mixtures thereof, containing carbon. The microspheres are prepared by first forming an aqueous alkaline solution of a salt of said metals which will precipitate to a solid form in a concentrated alkaline medium together with an alkaline polymerizable organic monomer and carbon,

G. Bezzi; A. Facchini; G. Martignani; M. Pastore

1980-01-01

351

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

Microsoft Academic Search

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

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

2009-01-01

352

Changes in the rheological properties of mixtures of water-soluble cellulose ethers under mechanical treatment  

Microsoft Academic Search

Aqueous solutions of cellulose ethers and their mixtures are widely used in various technological processes. It is often desirable to achieve such a structural organization of a solution that the technologically necessary viscosity of the solution occurs at the minimum possible polymer concentration. One of the methods for thickening polysaccharide solutions is their mechanical treatment in various apparatuses. In this

R. F. Ganiev; O. V. Alekseeva; O. V. Rozhkova; V. A. Padokhin; Ya. A. Anikin

2007-01-01

353

Novel anisole mixture and gasoline containing the same  

DOEpatents

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.

Singerman, Gary M. (Monroeville, PA)

1982-01-26

354

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

DOEpatents

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

Janikowski, Stuart K. (Idaho Falls, ID)

2000-01-01

355

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...

356

Lattice Boltzmann model for binary mixtures.  

PubMed

An a priori derivation of the lattice Boltzmann equations for binary mixtures is provided by discretizing the Boltzmann equations that govern the evolution of binary mixtures. The present model leads to a set of two-fluid hydrodynamic equations for the mixture. In existing models, employing the single-relaxation-time approximation, the viscosity and diffusion coefficients are coupled through the relaxation parameter tau, thus limited to unity Prandtl number and Schmidt number. In the present model the viscosity and diffusion coefficient are independently controlled by two relaxation parameters, thus enabling the modeling of mixtures with an arbitrary Schmidt number. The theoretical framework developed here can be readily applied to multiple-species mixing. PMID:12366175

Luo, Li-Shi; Girimaji, Sharath S

2002-09-01

357

Assessing exposures to inhaled complex mixtures.  

PubMed Central

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

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

1993-01-01

358

Uncertainty in Mixtures and Cumulative Risk Assessment  

EPA Science Inventory

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

359

Predicting skin permeability from complex chemical mixtures  

SciTech Connect

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 index, polarizability and log (1/Henry's Law Constant) of the mixture components. These factors should not be considered final as the focus of these studies was solely to determine if knowledge of the physical properties of a mixture would improve predicting skin permeability. Inclusion of multiple mixture factors should further improve predictability. The importance of these findings is that there is an approach whereby the effects of a mixture on dermal absorption of a penetrant of interest can be quantitated in a standard QSPeR model if physicochemical properties of the mixture are also incorporated.

Riviere, Jim E. [Center for Chemical Toxicology Research and Pharmacokinetics, 4700 Hillsborough Street, North Carolina State University, Raleigh, NC 27606 (United States)]. E-mail: Jim_Riviere@ncsu.edu; Brooks, James D. [Center for Chemical Toxicology Research and Pharmacokinetics, 4700 Hillsborough Street, North Carolina State University, Raleigh, NC 27606 (United States)

2005-10-15

360

Phase equilibria in quadrupolar fluid binary mixtures  

NASA Astrophysics Data System (ADS)

Phase equilibria in fluid binary mixtures of nonpolar-quadrupolar and quadrupolar-quadrupolar fluids are investigated using the perturbation scheme of Scalise et al. (1987). It is found that a molecular model with a Lennard-Jones function and a quadrupole-quadrupole interaction as the perturbing potential to the hard-sphere fluid reference system is able to predict the shape of the coexistence curves observed in He-N2, H2-N2, and Ne-N2 mixtures.

Scalise, O. H.; Gianotti, R. D.; Zarragoicoechea, G. J.; Rodriguez, A. E.

1988-07-01

361

Thermal conductivity of nanoparticle-fluid mixture  

Microsoft Academic Search

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

X. Wang; Xianfan Xu

1999-01-01

362

Flash evaporation of liquid monomer particle mixture  

DOEpatents

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.

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

1999-01-01

363

Flash evaporation of liquid monomer particle mixture  

DOEpatents

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.

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

1999-05-11

364

Speaker Verification Using Adapted Gaussian Mixture Models  

Microsoft Academic Search

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

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

2000-01-01

365

PVT measurements for five natural gas mixtures  

E-print Network

Major Subject: Chemical Engineering PVT MEASUREMENTS FOR FIVE NATURAL GAS MIXTURES A Thesis by PHILIP PARAYIL SIMON Approved as to style and content by: James C. Holste (Chair of Committee) Kenneth N. Marsh (Member) Randolph C. Wilhoit (Member...) Raymond W. Flumerfelt (Head of Department) August 1991 ABSTRACT PVT Measurements for Five Natural Gas Mixtures (August 1991) Philip Parayil Simon, B. Tech. , Indian Institute of Technology, Madras Chair of Advisory Committee: Dr. James C. Holste...

Simon, Philip Parayil

1991-01-01

366

(Gaussian Mixture Model : GMM) (Non-negative  

E-print Network

, , ( ) 1 4 2 [1] 4 20% " " [2] [3] [4] (Gaussian Mixture Model : GMM) [2] [5] (Non-dictionary [7] NMF NMF NMF 2 NMF 3 4 GMM NMF 5 2 NMF xl J j=1 ajhj,l = Ahl (1) xl l D aj j hj,l aj A = [a1 K s k = [x (k) 1 , . . . , x (k) Nk ] (4) s k Nk k Gaussian Mixture Model (GMM) p(x(k) n ) = Mk m=1

Takiguchi, Tetsuya

367

Phase equilibria for complex fluid mixtures  

SciTech Connect

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.

Prausnitz, J.M.

1983-04-01

368

Stability of supercooled binary liquid mixtures  

NASA Astrophysics Data System (ADS)

Recently, the supercooled Wahnström binary Lennard-Jones mixture was partially crystallized into MgZn2 phase crystals in lengthy molecular dynamics simulations. We present molecular dynamics simulations of a modified Kob-Andersen binary Lennard-Jones mixture that also crystallizes in lengthy simulations here, however, by forming pure fcc crystals of the majority component. The two findings motivate this paper that gives a general thermodynamic and kinetic treatment of the stability of supercooled binary mixtures, emphasizing the importance of negative mixing enthalpy whenever present. The theory is used to estimate the crystallization time in a Kob-Andersen mixture from the crystallization time in a series of related systems. At T =0.40 we estimate this time to be 5×107 time units (?0.1 ms). A new binary Lennard-Jones mixture is proposed that is not prone to crystallization and faster to simulate than the two standard binary Lennard-Jones mixtures. This is obtained by removing the like-particle attractions by switching to Weeks-Chandler-Andersen type potentials, while maintaining the unlike-particle attraction.

Toxvaerd, Søren; Pedersen, Ulf R.; Schrøder, Thomas B.; Dyre, Jeppe C.

2009-06-01

369

Destruction of volatile organic compounds via catalytic incineration (journal version)  

Microsoft Academic Search

This paper gives results of an investigation of the effect of catalytic incinerator design and operation on the destruction of specific volatile organic compounds (VOCs), both singly and in mixtures. A range of operating and design parameters were tested on a wide variety of compounds and compound mixtures. Conclusions of the study, presented here as applying only to the test

M. A. Palazzolo; B. A. Tichenor

1987-01-01

370

Destruction of volatile organic compounds via catalytic incineration  

Microsoft Academic Search

The paper gives results of an investigation of the effect of catalytic-incinerator design and operation the destruction of specific volatile organic compounds (VOCs), both singly and in mixtures. A range of operating and design parameters were tested on a wide variety of compounds and compound mixtures. Conclusions of the study, presented here as applying only to the test catalyst and

B. A. Tichenor; M. A. Palazzolo

1985-01-01

371

A novel method dependent only on the mixture information (MIM) for evaluating the toxicity of mixture.  

PubMed

Compound contamination and toxicity interaction necessitate the development of models that have an insight into the combined toxicity of chemicals. In this paper, a novel and simple model dependent only on the mixture information (MIM), was developed. Firstly, the concentration-response data of seven groups of binary and multi-component (pseudo-binary) mixtures with different mixture ratios to Vibrio qinghaiensis sp.-Q67 were determined using the microplate toxicity analysis. Then, a desirable non-linear function was selected to fit the data. It was found that there are good linear correlations between the location parameter (?) and mixture ratio (p) of a component and between the steepness (?) and p. Based on the correlations, a mixture toxicity model independent of pure component toxicity profiles was built. The model can be used to accurately estimate the toxicities of the seven groups of mixtures, which greatly simplified the predictive procedure of the combined toxicity. PMID:21531059

Zhang, Jin; Liu, Shu-Shen; Liu, Hai-Ling; Zhu, Xiang-Wei; Mi, Xiao-Juan

2011-07-01

372

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

373

A novel method dependent only on the mixture information (MIM) for evaluating the toxicity of mixture  

Microsoft Academic Search

Compound contamination and toxicity interaction necessitate the development of models that have an insight into the combined toxicity of chemicals. In this paper, a novel and simple model dependent only on the mixture information (MIM), was developed. Firstly, the concentration–response data of seven groups of binary and multi-component (pseudo-binary) mixtures with different mixture ratios to Vibrio qinghaiensis sp.-Q67 were determined

Jin Zhang; Shu-Shen Liu; Hai-Ling Liu; Xiang-Wei Zhu; Xiao-Juan Mi

2011-01-01

374

Evaluation of binary solvent mixtures for efficient monoacylglycerol production by continuous enzymatic glycerolysis.  

PubMed

This study was aimed at evaluating different binary solvent mixtures for efficient industrial monoacylglycerol (MAG) production by enzymatic glycerolysis. Of all investigated cases, the binary mixture of tert-butanol:tert-pentanol (TB:TP) 80:20 vol % was the most suitable organic medium for continuous enzymatic glycerolysis, ensuring high MAG formation in a short time, reasonable solvent price, and easy handling during distillation/condensation processing. A minimum solvent dosage of 44-54 wt % of the reaction mixture was necessary to achieve high MAG yields of 47-56 wt %, within 20 min. The melting and boiling points of the TB:TP mixture were estimated to be 7 and 85 degrees C, respectively, using thermodynamic models. These predictions were in good agreement with experimentally determined values. In spite of the high reaction efficiency in the binary TB:TP system, the mixture of glycerol and sunflower oil (containing 97.1% triacylglycerol) yielded surprisingly a liquid/liquid phase split behavior even at high temperatures (>80 degrees C). This in contrast to thermodynamic model calculations suggested full miscibility in all proportions. These findings suggest that enhanced reaction efficiency in organic solvent also depends upon aspects other than the system homogeneity such as reduced viscosity, reduced mass transfer limitations, and the accessibility of the substrate to the active site of the enzyme. PMID:16968070

Damstrup, Marianne L; Abildskov, Jens; Kiil, Søren; Jensen, Anker D; Sparsø, Flemming V; Xu, Xuebing

2006-09-20

375

ORGANIC CONTAMINANTS  

EPA Science Inventory

Organic pollutants may constitute the most widespread waste loadings into the waters of Lake Superior. There are essentially three categories of organic contaminants. The first grouping consists of those organic compounds that readily degrade biologically or chemically. The secon...

376

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

PubMed

A comparison of 4 metal-mixture toxicity models (that were based on the Biotic Ligand Model and WHAM-FTOX) was presented in the previous paper. In the present study, a streamlined version of the 4 models was developed and applied to multiple datasets and test conditions to examine key assumptions and calibration strategies that are crucial in modeling metal-mixture toxicity. Results show that: (i) a single binding site on or in the organism was a useful and oftentimes sufficient framework for predicting metal toxicity, (ii) a linear free energy relationship (LFER) for bidentate binding of metals and cations to the biotic ligand provided a good first estimate of binding coefficients, (iii) although adjustments in metal binding coefficients or adjustments in chemical potency factors can both be used in model calibration for single-metal exposures, changing metal binding coefficients or chemical potency factors had different effects on model predictions for metal mixtures, and (iv) selection of a mixture toxicity model (based on concentration addition or independent action) was important in predicting metal-mixture toxicity. In moving forward, efforts should focus on reducing uncertainties in model calibration, including development of better methods to characterize metal binding to toxicologically-active binding sites, conducting targeted exposure studies to advance the understanding of metal-mixture toxicity, and further developing LFERs and other tools to help constrain the model calibration. This article is protected by copyright. All rights reserved. PMID:25475765

Farley, Kevin J; Meyer, Joseph S

2014-12-01

377

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

PubMed

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

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

2015-02-11

378

Application of the electronic nose technique to differentiation between model mixtures with COPD markers.  

PubMed

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

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

2013-01-01

379

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

PubMed Central

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

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

2013-01-01

380

Deliquescence behavior of organic\\/ammonium sulfate aerosol  

Microsoft Academic Search

Received 15 January 2002; revised 16 May 2002; accepted 23 May 2002; published 8 October 2002. (1) Recent studies have shown that tropospheric aerosols composed of internal mixtures of organics with sulfates are quite common with the organic composing up to 50% of the particle mass. The influences of the organics on the chemical and physical properties of the aerosol

Sarah D. Brooks; Matthew E. Wise; Melinda Cushing; Margaret A. Tolbert

2002-01-01

381

EVALUATION OF CRYOGENIC TRAPPING AS A MEANS FOR COLLECTING ORGANIC COMPOUNDS IN AMBIENT AIR  

EPA Science Inventory

The methodology used in reduced temperature preconcentration of volatile organic compounds has been tested using a prototype automated gas chromatographic system. Mixtures of sixteen volatile organic compounds in humidified zero air were passed through a Nafion tube dryer and the...

382

Separations of cyclic, branched, and linear hydrocarbon mixtures through silicalite membranes  

SciTech Connect

Binary and ternary mixtures of organic vapors were separated at elevated temperatures with a silicalite zeolite membrane on a porous, tabular, alumina support. Linear alkanes, branched alkanes, aromatics, and saturated ring compounds were used as feeds, and permeances of pure compounds and mixtures were measured between 360 and 510 K. Pure compound permeances of the linear alkanes strongly decrease with increasing chain length, whereas the branched and cyclic compounds permeate at rates similar to those of n-hexane and n-heptane. Almost all permeances increase with increasing temperature. Mixtures of branched or cyclic molecules with small linear alkanes were readily separated with high selectivities (over 200 for n-hexane/benzene), even though the ratios of pure component permeances were small. The separation behavior is not due to molecular sieving but instead appears to be due to preferential adsorption (adsorption on external surface, pore entering, adsorption in pores) of one species, which prevents the other organics from adsorbing and transporting through the membrane. Mixtures of cyclic or branched molecules showed small or no separations. For all systems, separations factors decrease as temperature increases apparently because preferential adsorption becomes less important at elevated temperatures. For mixtures of benzene or methylyclohexane with 2,2,4-trimethylpentane and for mixtures of 2,2-dimethylbutane with 3-methylpentane, both compounds permeated at similar rates and no separations were obtained. Single-file transport in the zeolite channels is suspected to limit transport. The membranes have intercrystalline regions in parallel with the zeolite pores that may also permeate the organics.

Funke, H.H.; Argo, A.M.; Falconer, J.L.; Noble, R.D. [Univ. of Colorado, Boulder, CO (United States). Dept. of Chemical Engineering] [Univ. of Colorado, Boulder, CO (United States). Dept. of Chemical Engineering

1997-01-01

383

Behavior of complex mixtures in aquatic environments: a synthesis of PNL ecological research  

SciTech Connect

The term complex mixture has been recently applied to energy-related process streams, products and wastes that typically contain hundreds or thousands of individual organic compounds, like petroleum or synthetic fuel oils; but it is more generally applicable. A six-year program of ecological research has focused on four areas important to understanding the environmental behavior of complex mixtures: physicochemical variables, individual organism responses, ecosystems-level determinations, and metabolism. Of these areas, physicochemical variables and organism responses were intensively studied; system-level determinations and metabolism represent more recent directions. Chemical characterization was integrated throughout all areas of the program, and state-of-the-art methods were applied. 155 references, 35 figures, 4 tables.

Fickeisen, D.H.; Vaughan, B.E. (eds.)

1984-06-01

384

Metabolic changes of Vitis vinifera berries and leaves exposed to Bordeaux mixture.  

PubMed

Since the development of Bordeaux mixture in the late 1800's, copper-based fungicides have been widely used against grapevine (Vitis vinifera L.) diseases, mainly in organic but also in conventional viticulture; however their intensive use has raised phytotoxicity concerns. In this study, the composition of grape berries and leaves upon Bordeaux mixture treatment was investigated during the fructification season by a metabolomic approach. Four applications of Bordeaux mixture till 3 weeks before harvest were performed following the regular management practices of organic viticulture. Results showed that the copper-based treatment affected the content in sugars, organic acids, lipids and flavan-3-ols of grapes and leaves at specific developmental stages. Nonetheless, the levels of sucrose, glucose and fructose, and of tartaric and malic acids were not significantly affected in mature grapes. In contrast, a sharp decrease in free natural amino acids was observed, together with a reduction in protein content and in mineral nitrogen forms. The treatment with Bordeaux mixture increased by 7-fold the copper levels in tissue extracts from surface-washed mature berries. PMID:25022258

Martins, Viviana; Teixeira, António; Bassil, Elias; Blumwald, Eduardo; Gerós, Hernâni

2014-09-01

385

rH-metric controls and primary standardization in aqueous-organic media.  

PubMed

The rationale for the extension of the rH-metric standardization and measurements to aqueous-organic solvent mixtures is here introduced, and examples of establishment of the ranges of conventional rH-metric scales as well as primary standards rHs in some typical aqueous-organic solvent mixtures are described. PMID:12489260

Falciola, Luigi; Mussini, Patrizia R; Mussini, Torquato

2002-10-01

386

Deconvolution of spectra for intimate mixtures  

NASA Technical Reports Server (NTRS)

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.

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

1987-01-01

387

Mixture Models for Distance Sampling Detection Functions  

PubMed Central

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

Miller, David L.; Thomas, Len

2015-01-01

388

Coal-water mixture fuel burner  

DOEpatents

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.

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

1985-04-29

389

Bounded asymmetrical Student's-t mixture model.  

PubMed

The finite mixture model based on the Student's-t distribution, which is heavily tailed and more robust than the Gaussian mixture model (GMM), is a flexible and powerful tool to address many computer vision and pattern recognition problems. However, the Student's-t distribution is unbounded and symmetrical around its mean. In many applications, the observed data are digitalized and have bounded support. The distribution of the observed data usually has an asymmetric form. A new finite bounded asymmetrical Student's-t mixture model (BASMM), which includes the GMM and the Student's-t mixture model (SMM) as special cases, is presented in this paper. We propose an extension of the Student's-t distribution in this paper. This new distribution is sufficiently flexible to fit different shapes of observed data, such as non-Gaussian, nonsymmetric, and bounded support data. Another advantage of the proposed model is that each of its components can model the observed data with different bounded support regions. In order to estimate the model parameters, previous models represent the Student's-t distributions as an infinite mixture of scaled Gaussians. We propose an alternate approach in order to minimize the higher bound on the data negative log-likelihood function, and directly deal with the Student's-t distribution. As an application, our method has been applied to image segmentation with promising results. PMID:23893763

Nguyen, Thanh Minh; Wu, Q M Jonathan

2014-06-01

390

A cold energy mixture theory for the equation of state in solid and porous metal mixtures  

NASA Astrophysics Data System (ADS)

Porous or solid multi-component mixtures are ubiquitous in nature and extensively used as industrial materials such as multifunctional energetic structural materials (MESMs), metallic and ceramic powder for shock consolidation, and porous armor materials. In order to analyze the dynamic behavior of a particular solid or porous metal mixture in any given situation, a model is developed to calculate the Hugoniot data for solid or porous mixtures using only static thermodynamic properties of the components. The model applies the cold energy mixture theory to calculate the isotherm of the components to avoid temperature effects on the mixtures. The isobaric contribution from the thermodynamic equation of state is used to describe the porous material Hugoniot. Dynamic shock responses of solid or porous powder mixtures compacted by shock waves have been analyzed based on the mixture theory and Hugoniot for porous materials. The model is tested on both single-component porous materials such as aluminum 2024, copper, and iron; and on multi-component mixtures such as W/Cu, Fe/Ni, and Al/Ni. The theoretical calculations agree well with the corresponding experimental and simulation results. The present model produces satisfactory correlation with the experimentally obtained Hugoniot data for solid porous materials over a wide pressure range.

Zhang, X. F.; Qiao, L.; Shi, A. S.; Zhang, J.; Guan, Z. W.

2011-07-01

391

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...

392

Taste mixture interactions: Suppression, additivity, and the predominance of sweetness  

Microsoft Academic Search

Most of what is known about taste interactions has come from studies of binary mixtures. The primary goal of this study was to determine whether asymmetries in suppression between stimuli in binary mixtures predict the perception of tastes in more complex mixtures (e.g., ternary and quaternary mixtures). Also of interest was the longstanding question of whether overall taste intensity derives

Barry G. Green; Juyun Lim; Floor Osterhoff; Karen Blacher; Danielle Nachtigal

2010-01-01

393

Mixture autoregressive hidden Markov models for speech signals  

Microsoft Academic Search

In this paper a signal modeling technique based upon finite mixture autoregressive probabilistic functions of Markov chains is developed and applied to the problem of speech recognition, particularly speaker-independent recognition of isolated digits. Two types of mixture probability densities are investigated: finite mixtures of Gaussian autoregressive densities (GAM) and nearest-neighbor partitioned finite mixtures of Gaussian autoregressive densities (PGAM). In the

Biing-Hwang Juang; LAWRENCE R. RABINER

1985-01-01

394

Spectrofluorometric analysis of amino acid mixtures: Implications for future space missions  

NASA Astrophysics Data System (ADS)

Efficient detection of organic molecules is fundamental for the success of future life detection missions. Spectrofluorometric analysis is one of the many techniques that may be used to detect organic molecules in extraterrestrial settings. A particularly important class of organic molecules to target is the amino acids on which all terrestrial life depends. This study aims to identify the optimum fluorescence excitation and emission wavelengths for 17 amino acid standards to examine the effects of amino acid concentrations, mixtures and fluorescence quenching. The results and interpretations can guide the design and operation of life detection protocols on future space missions.

Chan, Hoi S.; Martins, Zita; Sephton, Mark A.

2012-01-01

395

Brief report on primary mixture preparation for precise CO observation  

NASA Astrophysics Data System (ADS)

Greenhouse gases (GHG) have been known as causing materials of the greenhouse effect. Because it is very important to reduce their emission, they has been paid attention since Kyoto protocol to the United Nations Framework Convention on Climate Change. Accurate observation data of ambient GHG are vital for the study of the relationship between GHGs and global warming, but it is not easy to quantify their mixing ratios owing to their globally and temporally tiny variation. For example, mixing ratio of carbon dioxide in the atmosphere, is reported to be growing by +1.7 ppm (parts per million)/year for recen 10 years according to GAW report. CO has contributed as an indicator in that an air mass is from source or background, although it lacks its traceability. CO is known to be emitted from industry, vehicle, and biomass burning. The atmospheric lifetime of CO varies from weeks to months depending on OH radical amount however ambient CO ranges from 50 nmol/mol to 300 nmol/mol at marine boundary, from 100 nmol/mol to 500 nmol/mol at city area. In order to monitor precisely CO at ambient, the World Meteorological Organization (WMO) requires its measurement capability of 2 nmol/mol uncertainty. For these reasons, it's necessary for the measurement results to be accurate and consistent among the assigned standards. . In order to prepare CO/air standard mixtures with an absolute scale we have studied several factors on gravimetry; purity analysis of CO and an artificial air and stability including unexpected contamination during preparation and adsorption on inner wall of cylinders. Currently we are going to present the preliminary results on the development of standard mixtures with ~ 300 nmol/mol. The mixtures were verified by comparing their amount with a Gas Chromatography / Electron Capture Detector (GC/FID) and cavity ring down spectrometer (CRDS). Analytical capability during comparison is within ± 2 ppb, which satisfies WMO DQO.

Lee, J.; Lee, J. B.; Moon, D. M.; Kim, J. S.

2012-04-01

396

Permeation of chemical protective clothing by three binary solvent mixtures  

SciTech Connect

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.

Mickelsen, R.L.; Roder, M.M.; Berardinelli, S.P.

1986-04-01

397

Mixtures of planetary ices at extreme conditions.  

PubMed

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

Lee, Mal-Soon; Scandolo, Sandro

2011-01-01

398

Detailed Kinetic Modeling of Gasoline Surrogate Mixtures  

SciTech Connect

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.

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

2009-03-09

399

Docosahexaenoic acid promotes micron scale liquid-ordered domains. A comparison study of docosahexaenoic versus oleic acid containing phosphatidylcholine in raft-like mixtures.  

PubMed

The understanding of the functional role of the lipid diversity in biological membranes is a major challenge. Lipid models have been developed to address this issue by using lipid mixtures generating liquid-ordered (Lo)/liquid-disordered (Ld) immiscibility. The present study examined mixtures comprising Egg sphingomyelin (SM), cholesterol (chol) and phosphatidylcholine (PC) either containing docosahexaenoic (PDPC) or oleic acid (POPC). The mixtures were examined in terms of their capability to induce phase separation at the micron- and nano-scales. Fluorescence microscopy, electron spin resonance (ESR), X-ray diffraction (XRD) and calorimetry methods were used to analyze the lateral organization of the mixtures. Fluorescence microscopy of giant vesicles could show that the temperature of the micron-scale Lo/Ld miscibility is higher for PDPC than for POPC ternary mixtures. At 37°C, no micron-scale Lo/Ld phase separation could be identified in the POPC containing mixtures while it was evident for PDPC. In contrast, a phase separation was distinguished for both PC mixtures by ESR and XRD, indicative that PDPC and POPC mixtures differed in micron vs nano domain organization. Compared to POPC, the higher line tension of the Lo domains observed in PDPC mixtures is assumed to result from the higher difference in Lo/Ld order parameter rather than hydrophobic mismatch. PMID:25767038

Georgieva, R; Chachaty, C; Hazarosova, R; Tessier, C; Nuss, P; Momchilova, A; Staneva, G

2015-06-01

400

Thermophysical Properties of Fluids and Fluid Mixtures  

SciTech Connect

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.

Sengers, Jan V.; Anisimov, Mikhail A.

2004-05-03

401

Rheology of Dense Granular Mixtures: Boundary Pressures  

NASA Astrophysics Data System (ADS)

Models for dense sheared granular materials indicate that their rheological properties depend on particle size, but the representative size for mixtures is not obvious. Here, we computationally study pressure on a boundary due to sheared granular mixtures to determine its dependence on particle size distribution. We find that the pressure does not depend monotonically on average particle size. Instead it has an additional dependence on a measure of the effective free volume per particle we adapt from an expression for packing of monosized particles near the jammed state.

Hill, K. M.; Yohannes, B.

2011-02-01

402

Diffusion in mercury-argon gas mixtures  

NASA Astrophysics Data System (ADS)

Ab initio quantum-mechanical calculations of potential of interactions U( R) are performed for Hg-Ar. Using equations from the molecular kinetic theory of rarefied gases, a new statistical correlation is found between data on the potential of interaction (molecular beams, molecular spectroscopy, and potential U( R)) and experimental data on the mutual diffusion coefficient (MDC) of mercury-argon gas mixtures. Calculated reference data on the MDC of mercury-argon gas mixtures in the temperature range of 300 to 600 K are offered as a possible standard for calibrating instruments that measure MDCs of liquid vapors and inert gases using the Stefan method.

Meshkov, V. V.; Popov, V. N.; Fokin, L. R.

2014-04-01

403

Instabilities in complex mixtures with a large number of components  

E-print Network

Inside living cells are complex mixtures of thousands of components. It is hopeless to try to characterise all the individual interactions in these mixtures. Thus, we develop a statistical approach to approximating them, and examine the conditions under which the mixtures phase separate. The approach approximates the matrix of second virial coefficients of the mixture by a random matrix, and determines the stability of the mixture from the spectrum of such random matrices.

Richard P. Sear; Jose A. Cuesta

2003-07-14

404

Prebiotic chemistry within a simple impacting icy mixture.  

PubMed

We present results of prebiotic organic synthesis in shock compressed mixtures of simple ices from quantum molecular dynamics (MD) simulations extended to close to equilibrium time scales. Given the likelihood of an inhospitable prebiotic atmosphere on early Earth, it is possible that impact processes of comets or other icy bodies were a source of prebiotic chemical compounds on the primitive planet. We observe that moderate shock pressures and temperatures within a CO2-rich icy mixture (36 GPa and 2800 K) produce a number of nitrogen containing heterocycles, which dissociate to form functionalized aromatic hydrocarbons upon expansion and cooling to ambient conditions. In contrast, higher shock conditions (48-60 GPa, 3700-4800 K) resulted in the synthesis of long carbon-chain molecules, CH4, and formaldehyde. All shock compression simulations at these conditions have produced significant quantities of simple C-N bonded compounds such as HCN, HNC, and HNCO upon expansion and cooling to ambient conditions. Our results elucidate a mechanism for impact synthesis of prebiotic molecules at realistic impact conditions that is independent of external constraints such as the presence of a catalyst, illuminating UV radiation, or pre-existing conditions on a planet. PMID:23639050

Goldman, Nir; Tamblyn, Isaac

2013-06-20

405

Dynamic responses of Bacteroides thetaiotaomicron during growth on glycan mixtures  

PubMed Central

Summary Bacteroides thetaiotaomicron (Bt) is a human colonic symbiont that degrades many different complex carbohydrates (glycans), the identities and amounts of which are likely to change frequently and abruptly from meal-to-meal. To understand how this organism reacts to dynamic growth conditions, we challenged it with a series of different glycan mixtures and measured responses involved in glycan catabolism. Our results demonstrate that individual Bt cells can simultaneously respond to multiple glycans and that responses to new glycans are extremely rapid. The presence of alternative carbohydrates does not alter response kinetics, but reduces expression of some glycan utilization genes as well as the cell’s sensitivity to glycans that are present in lower concentration. Growth in a mixture containing twelve different glycans revealed that Bt preferentially uses some before others. This metabolic hierarchy is not changed by prior exposure to lower priority glycans because re-introducing high priority substrates late in culture re-initiates repression of genes involved in degrading those with lower priority. At least some carbohydrate prioritization effects occur at the level of monosaccharide recognition. Our results provide insight into how a bacterial glycan generalist modifies its responses in dynamic glycan environments and provide essential knowledge to interpret related metabolic behavior in vivo. PMID:23646867

Rogers, Theresa E.; Pudlo, Nicholas A.; Koropatkin, Nicole M.; Bell, Joshua S. K.; Balasch, Monica Moya; Jasker, Kevin; Martens, Eric C.

2013-01-01

406

Dynamics of binary phase separation in liquid He-3-He-4 mixtures  

NASA Technical Reports Server (NTRS)

Binary phase-separation dynamics in liquid mixtures of He-3 and He-4 has been investigated near the tricritical point with laser-light scattering techniques. Rapid decompression of the mixtures results in quenches into the miscibility gap so that both the metastable and unstable (spinodal) regions can be probed. Quenches into the unstable region allowed measurements of the normalized dynamic structure factor S(k,t) that confirm the dynamical scaling hypotheses for spinodal decomposition. Measurements made for concentrations well away from the tricritical value show different behavior and suggest the presence of a spinodal boundary. Forward scattering intensities for shallow quenches probe nucleation phenomena and permit quantitative measurements of anomalous super-cooling as a function of quench rate. Comparisons with data in organic binary mixtures are given.

Hoffer, J. K.; Sinha, D. N.

1986-01-01

407

Differential viability of phosphoglucose isomerase allozyme genotypes of marine snails in nonionic detergent and crude oil-surfactant mixtures  

SciTech Connect

The effects of a nonionic detergent and of crude oil-detergent mixtures in aqueous solutions on the allozyme frequencies of phosphoglucose isomerase (Pgi) genotypes were tested in the Mediterranean marine gastropods Monodonta turbinata and M. turbiformis. Our results indicate differential survivorship of electrophoretical Pgi allozyme genotypes for both detergent alone and for crude oil-detergent mixtures. These results reflect the adaptive nature of some Pgi genotypes in these marine gastropods and seem inconsistent with the neutral theory of allozyme polymorphisms. Furthermore, these findings suggest that allozyme variants demonstrate a differential tolerance to these organic pollutants and can, therefore, be used as detectors of organic pollutants in the sea.

Lavie, B.; Nevo, E.; Zoller, U.

1984-10-01

408

MixtureTree Annotator: A Program for Automatic Colorization and Visual Annotation of MixtureTree  

PubMed Central

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

Chen, Shu-Chuan; Ogata, Aaron

2015-01-01

409

MixtureTree Annotator: A Program for Automatic Colorization and Visual Annotation of MixtureTree.  

PubMed

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

Chen, Shu-Chuan; Ogata, Aaron

2015-01-01

410

21 CFR 82.6 - Certifiable mixtures.  

Code of Federal Regulations, 2010 CFR

...coal-tar color used as an ingredient in mixing such batch is from a previously certified...such previous certification, except by mixing into such batch of mixture; (2...coal-tar color used as an ingredient in mixing such batch is from a previously...

2010-04-01

411

Aging effects on transformer oil mixtures  

Microsoft Academic Search

The authors present results of an extensive experimental study to investigate aging effects on transformer oil mixtures (TOMs). Accelerated aging was applied to TOM samples of different relative volumetric percentages using different doses of ?-irradiation. The electrical and physical properties of a variety of samples were measured, e.g., dielectric strength, dielectric loss, specific gravity, viscosity, and flash point. Also, a

M. Elshazly-Zaghloul; B. A. Badawy; A. El-Meligy

1990-01-01

412

A Poisson mixture model of discrete choice  

Microsoft Academic Search

In this paper, we introduce a new Poisson mixture model for count panel data where the underlying Poisson process intensity is determined endogenously by consumer latent utility maximization over a set of choice alternatives. This formulation accommodates the choice and count in a single random utility framework with desirable theoretical properties. Individual heterogeneity is introduced through a random coefficient scheme

Martin Burda; Matthew Harding; Jerry Hausman

2012-01-01

413

3B. Observed vs. predicted mixture INTRODUCTION  

E-print Network

moisture and temperature distributions in litter layers. We examine decomposition in northeastern forests of litter-mix experiments? MATERIALS AND METHODS Freshly senesced sugar maple and red oak leaf litter in mixtures of multiple litter types can differ from predictions based on components species decaying alone1

Jackson, Robert B.

414

Methods and systems for deacidizing gaseous mixtures  

DOEpatents

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.

Hu, Liang

2010-05-18

415

Design and Proportioning of Concrete Paving Mixtures  

E-print Network

Adapted from Hover Guide - Mixture design...? #12;Mix Design Requirements Materials Characteristics fl oz Adapted from Hover #12;Tentative Timetable Tentative TIMETABLE... March 08 ­ Develop framework/Consulting: Farid Hamad (Lane) Tom Vandam Pete Capon (Rieth Riley) Ken Hover Mark Brown (Zachry) Jay Shilstone

416

Binary ionic mixtures and a solvable model  

Microsoft Academic Search

The theory of solutions of McMillan and Mayer is applied to the jellium model of a binary ionic mixture: two species of charged particles, with charges e and Ze, immersed in a neutralizing background. The density rho2 of the particles of charge Ze is considered as small, and is used as an expansion parameter. The free energy, the pair distribution

B. Jancovici

1984-01-01

417

Superconductor precursor mixtures made by precipitation method  

DOEpatents

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.

Bunker, Bruce C. (Albuquerque, NM); Lamppa, Diana L. (Albuquerque, NM); Voigt, James A. (Albuquerque, NM)

1989-01-01

418

Putting Priors in Mixture Density Mercer Kernels  

Microsoft Academic Search

This paper presents a new methodology for automatic knowl- edge driven data mining based on the theory of Mercer Ker- nels, which are highly nonlinear symmetric positive denite mappings from the original image space to a very high, possibly innite dimensional feature space. We describe a new method called Mixture Density Mercer Kernels to learn kernel function directly from data,

Ashok N. Srivastava; Johann Schumann; Bernd Fischer; Mercer Kernels

419

Mixtures of Large Margin Nearest Neighbor Classifiers  

E-print Network

that learns a global Mahalanobis distance. We propose a mixture of such classifiers where a gating function structure as given by a covariance matrix S, one should use the Mahalanobis distance: DM = (xi - xj) M symmetric Mahalanobis matrix can be factorized as M = L L, where L is an e × d projection matrix and e d

Alpaydýn, Ethem

420

Machine Learning ! ! ! ! ! Srihari Mixture of Gaussians  

E-print Network

Machine Learning ! ! ! ! ! Srihari 1 Mixture of Gaussians Sargur Srihari srihari@cedar · Responsibility is associated with data point xn · Color using proportion of red, blue and green ink ­If for a data point it is colored red ­If for another point it has

421

Ternary gas mixture for diffuse discharge switch  

DOEpatents

A new diffuse discharge gas switch wherein a mixture of gases is used to take advantage of desirable properties of the respective gases. There is a conducting gas, an insulating gas, and a third gas that has low ionization energy resulting in a net increase in the number of electrons available to produce a current.

Christophorou, Loucas G. (Oak Ridge, TN); Hunter, Scott R. (Oak Ridge, TN)

1988-01-01

422

Video Compressive Sensing Using Gaussian Mixture Models  

E-print Network

and segmentation [15, 16], as well as image denoising, inpainting and deblurring [17, 18]. Recent work has of temporal compression. Index Terms--Compressive sensing, Gaussian mixture model, online learning, coded- struct frames from a single coded exposure photograph. Reddy et al. [4] developed a programmable

Carin, Lawrence

423

Bayesian Inference on Mixtures of Distributions  

Microsoft Academic Search

This survey covers state-of-the-art Bayesian techniques for the estimation of mixtures. It complements the earlier Marin, Mengersen and Robert (2005) by studying new types of distributions, the multinomial, latent class and t distributions. It also exhibits closed form solutions for Bayesian inference in some discrete setups. Lastly, it sheds a new light on the computation of Bayes factors via the

Kate Lee; Jean-Michel Marin; Kerrie Mengersen

2008-01-01

424

Membrane potential in multi-ionic mixtures.  

PubMed

The membrane potential arising through charged porous membranes separating electrolyte mixtures at identical hydrostatic pressures but different concentrations was investigated theoretically by means of the steric, electric, and dielectric exclusion (SEDE) model. Transport phenomena were described through the Nernst-Planck formalism, while ion partitioning at the membrane/solution interfaces was accounted for by means of modified Donnan equations including steric and dielectric effects. The high concentration limit of the membrane potential depends on the mixture composition and the pore size as well. A specific feature of membrane potential in multi-ionic systems is the dependence at high concentration on the effective dielectric constant of the solution confined inside pores. Indeed, the effective dielectric constant inside pores does not affect the high concentration limit of the membrane potential in the case of single salt solutions. The low concentration limit of the membrane potential is independent of the mixture composition, the effective dielectric constant inside pores, and the pore radius, but it is ruled by counterions with the highest charge number. The membrane potential measured at high salt concentration with single salt solutions and electrolyte mixtures could be used to determine the pore size and the effective dielectric constant inside pores, respectively. This may constitute an alternative way for membrane characterization with the advantage of avoiding the need for additional rejection rate measurements. PMID:19518100

Lanteri, Y; Szymczyk, A; Fievet, P

2009-07-01

425

Dynamical behaviour of rotated granular mixtures  

NASA Astrophysics Data System (ADS)

We present a phenomenological model for the dynamics of granular mixtures in a rotating drum. We demonstrate that our model successfully captures many of the experimental features known in the context of this problem. The results presented here are supplementary to those presented in a detailed paper (S. Puri, H. Hayakawa, cond-mat/9901260).

Puri, Sanjay; Hayakawa, Hisao

1999-08-01

426

(Gaussian Mixture Model) HMM (Hidden Markov  

E-print Network

( ) 1 [1] GMM (Gaussian Mixture Model) [2] HMM (Hidden Markov Model) 2 2.1 HMM s h o n O(; n) H function GMM for each position using H^ S H HOH ,|Prmaxarg^ GMM for each position ... 30 50H ... Fig. 1 HMM transfer function using the clean speech HMM HH |^Prmaxarg^ H GMM for each position H^ ... 30 50 Fig. 2 ^H

Takiguchi, Tetsuya

427

Gaussian Mixture Model (GMM) Global Variance  

E-print Network

NMF ( ) 1 [1, 2] [3] Gaussian Mixture Model (GMM) [4] [5, 6] [7] GMM Global Variance Helander [8] Partial Least Squares (PLS) GMM [9] Eigen-Voice GMM (EV-GMM)[10, 11] Sparse Coding Non-negative Matrix) Hs (4) NMF ^Xt = (At Hs ). M (8) STRAIGHT NMF STRAIGHT STRAIGHT STRAIGHT 2.5 NMF NMF NMF 3 3.1 GMM

Takiguchi, Tetsuya

428

Mixture model analysis of DNA microarray images  

Microsoft Academic Search

In this paper, we propose a new methodology for anal- ysis of microarray images. First, a new gridding algorithm is pro- posed for determining the individual spots and their borders. Then, a Gaussian mixture model (GMM) approach is presented for the analysis of the individual spot images. The main advantages of the proposed methodology are modeling flexibility and adaptability to

Konstantinos Blekas; Nikolas P. Galatsanos; Aristidis Likas; Isaac E. Lagaris

2005-01-01

429

Tribocharging of Three-Component Powder Mixtures  

Microsoft Academic Search

Adhesion of charged toner particles used in electrophotography is dominated by electrostatic forces. In this paper we discuss a model which describes the process by which toner particles acquire their electrostatic charge, tribocharging.In previous papers, we have presented a model of tribocharging of two-component mixtures of powders based on the assumptions that: 1. The surface of each powder is populated

J. H. Anderson; Elizabeth Fox

1995-01-01

430

Gene Expression Clustering with Functional Mixture Models  

E-print Network

Gene Expression Clustering with Functional Mixture Models Darya Chudova, Department of Computer measured on a discrete time grid. The model is specifically tailored to gene expression time course data of the model, and apply the proposed approach to the set of cycling genes in yeast. The experiments show

Mjolsness, Eric

431

Acute toxicity of mixture of acetaminophen and ibuprofen to Green Neon Shrimp, Neocaridina denticulate.  

PubMed

In recent years, numerous studies have indicated that various long-term use drugs, such as antibiotics or analgesics, not only cannot be completely decomposed via sewage treatment but also exhibit biological toxicity if they enter the environment; thus, the release of these drugs into the environment can damage ecological systems. This study sought to investigate the acute toxicity of two commonly utilized analgesics, ibuprofen (IBU) and acetaminophen (APAP), to aquatic organisms after these drugs have entered the water. To address this objective, the acute toxicity (median lethal concentration, LC??, for a 96-h exposure) of IBU alone, APAP alone, and mixtures containing different ratios of IBU and APAP in green neon shrimp (Neocaridina denticulata) were measured. The results of four tests revealed that the 96-h LC?? values for IBU and APAP alone were 6.07 mg/L and 6.60 mg/L, respectively. The 96-h LC?? for a 1:1 mixture of IBU and APAP was 6.23 mg/L, and the toxicity of this mixture did not significantly differ from the toxicity of either drug alone (p<0.05). The experimental results for mixtures containing unequal ratios of IBU and APAP indicated that mixtures with high APAP concentrations and low IBU concentrations exhibited markedly greater toxicity in N. denticulata (LC??=4.78 mg/L) than APAP or IBU alone. However, mixtures with high IBU concentrations and low APAP concentrations exhibited lower toxicity in N. denticulata (LC??=6.78 mg/L) than IBU or APAP alone. This study demonstrated that different mixtures of IBU and APAP were associated with different toxic effects in green neon shrimp. PMID:24860956

Sung, Hung-Hung; Chiu, Yuh-Wen; Wang, Shu-Yin; Chen, Chien-Min; Huang, Da-Ji

2014-07-01

432

Monitoring and optimizing the co-composting of dewatered sludge: a mixture experimental design approach.  

PubMed

The management of dewatered wastewater sludge is a major issue worldwide. Sludge disposal to landfills is not sustainable and thus alternative treatment techniques are being sought. The objective of this work was to determine optimal mixing ratios of dewatered sludge with other organic amendments in order to maximize the degradability of the mixtures during composting. This objective was achieved using mixture experimental design principles. An additional objective was to study the impact of the initial C/N ratio and moisture contents on the co-composting process of dewatered sludge. The composting process was monitored through measurements of O(2) uptake rates, CO(2) evolution, temperature profile and solids reduction. Eight (8) runs were performed in 100 L insulated air-tight bioreactors under a dynamic air flow regime. The initial mixtures were prepared using dewatered wastewater sludge, mixed paper wastes, food wastes, tree branches and sawdust at various initial C/N ratios and moisture contents. According to empirical modeling, mixtures of sludge and food waste mixtures at 1:1 ratio (ww, wet weight) maximize degradability. Structural amendments should be maintained below 30% to reach thermophilic temperatures. The initial C/N ratio and initial moisture content of the mixture were not found to influence the decomposition process. The bio C/bio N ratio started from around 10, for all runs, decreased during the middle of the process and increased to up to 20 at the end of the process. The solid carbon reduction of the mixtures without the branches ranged from 28% to 62%, whilst solid N reductions ranged from 30% to 63%. Respiratory quotients had a decreasing trend throughout the composting process. PMID:21565440

Komilis, Dimitrios; Evangelou, Alexandros; Voudrias, Evangelos

2011-09-01

433

Organ Transplantation  

MedlinePLUS

... organs that can be transplanted include Heart Intestine Kidney Liver Lung Pancreas You often have to wait a long time for an organ transplant. Doctors must match donors to recipients to reduce the risk of transplant rejection. Rejection ...

434

Laminar Flame Speeds of Moist Syngas Mixtures  

SciTech Connect

This work experimentally investigates the effect of the presence of water vapor on the laminar flame speeds of moist syngas/air mixtures using the counterflow twin-flame configuration. The experimental results presented here are for fuel lean syngas mixtures with molar percentage of hydrogen in the hydrogen and carbon monoxide mixture varying from 5% to 100%, for an unburned mixture temperature of 323 K, and under atmospheric pressure. At a given equivalence ratio, the effect of varying amount of water vapor addition on the measured laminar flame speed is demonstrated. The experimental laminar flame speeds are also compared with computed values using chemical kinetic mechanisms reported in the literature. It is found that laminar flame speed varies non-monotonically with addition of water for the carbon monoxide rich mixtures. It first increases with increasing amount of water addition, reaches a maximum value, and then decreases. An integrated reaction path analysis is further conducted to understand the controlling mechanism responsible for the non-monotonic variation in laminar flame speed due to water addition. On the other hand, for higher values of H{sub 2}/CO ratio the laminar flame speed monotonically decreases with increasing water addition. It is shown that the competition between the chemical and thermal effects of water addition leads to the observed response. Furthermore, reaction rate sensitivity analysis as well as binary diffusion coefficient sensitivity analysis are conducted to identify the possible sources of discrepancy between the experimental and predicted values. The sensitivity results indicate that the reaction rate constant of H{sub 2} + OH = H{sub 2}O + H is worth revisiting and refinement of binary diffusion coefficient data of N{sub 2}–H{sub 2}O, N{sub 2}–H{sub 2}, and H{sub 2}–H{sub 2}O pairs can be considered.

Das, A. K.; Kumar, K.; Zhang, Z.; Sung, C. J.

2011-01-01

435

Mixtures of Chemical Pollutants at European Legislation Safety Concentrations: How Safe Are They?  

PubMed Central

The risk posed by complex chemical mixtures in the environment to wildlife and humans is increasingly debated, but has been rarely tested under environmentally relevant scenarios. To address this issue, two mixtures of 14 or 19 substances of concern (pesticides, pharmaceuticals, heavy metals, polyaromatic hydrocarbons, a surfactant, and a plasticizer), each present at its safety limit concentration imposed by the European legislation, were prepared and tested for their toxic effects. The effects of the mixtures were assessed in 35 bioassays, based on 11 organisms representing different trophic levels. A consortium of 16 laboratories was involved in performing the bioassays. The mixtures elicited quantifiable toxic effects on some of the test systems employed, including i) changes in marine microbial composition, ii) microalgae toxicity, iii) immobilization in the crustacean Daphnia magna, iv) fish embryo toxicity, v) impaired frog embryo development, and vi) increased expression on oxidative stress-linked reporter genes. Estrogenic activity close to regulatory safety limit concentrations was uncovered by receptor-binding assays. The results highlight the need of precautionary actions on the assessment of chemical mixtures even in cases where individual toxicants are present at seemingly harmless concentrations. PMID:24958932

Carvalho, Raquel N.; Arukwe, Augustine; Ait-Aissa, Selim; Bado-Nilles, Anne; Balzamo, Stefania; Baun, Anders; Belkin, Shimshon; Blaha, Ludek; Brion, François; Conti, Daniela; Creusot, Nicolas; Essig, Yona; Ferrero, Valentina E. V.; Flander-Putrle, Vesna; Fürhacker, Maria; Grillari-Voglauer, Regina; Hogstrand, Christer; Jonáš, Adam; Kharlyngdoh, Joubert B.; Loos, Robert; Lundebye, Anne-Katrine; Modig, Carina; Olsson, Per-Erik; Pillai, Smitha; Polak, Natasa; Potalivo, Monica; Sanchez, Wilfried; Schifferli, Andrea; Schirmer, Kristin; Sforzini, Susanna; Stürzenbaum, Stephen R.; Søfteland, Liv; Turk, Valentina; Viarengo, Aldo; Werner, Inge; Yagur-Kroll, Sharon; Zounková, Radka; Lettieri, Teresa

2014-01-01

436

Organic contaminants in mountains.  

PubMed

The study of organic contaminants at high altitudes is motivated by the potential risk that they pose to humans living in, or depending on resources derived from, mountains and to terrestrial and aquatic ecosystems in alpine areas. Mountains are also ideal settings to study contaminant transport and behavior along gradients of climate and surface cover. Information on organic contaminants in mountains is compiled from the literature and synthesized, with a focus on atmospheric transport and deposition, contaminant dynamics in alpine lakes and aquatic organisms, and concentration differences with altitude. Diurnal mountain winds, in connection with enhanced deposition at higher elevations caused by low temperatures and high precipitation rates, conspire to make mid-latitude mountains become convergence zones for selected persistent organic chemicals. In particular, the more volatile constituents of contaminant mixtures seem to become enriched, relative to the less volatile constituents at higher altitudes. For selected contaminants, concentration inversions (i.e., concentrations that increase with elevation) have been observed. A notable difference between cold trapping in high latitudes and high altitudes is the likely importance of precipitation. High rates of snow deposition in mid- and high-latitude mountains may lead to a large contaminant release during snowmelt. Regions above the tree line often have little capacity to retain the released contaminants, suggesting the potential for a highly dynamic contaminant fate situation during the snow-free season with significant revolatilization and runoff. The chemical and environmental factors that control the orographic cold trapping of organic contaminants should be examined further by measuring and comparatively interpreting concentration gradients along several mountain slopes with widely different characteristics. Future efforts should further focus on the bioaccumulation and potential effects of contaminants in the upper trophic levels of alpine food chains, on measuring more water-soluble, persistent organic contaminants, and on studying how climate change may affect contaminant dynamics in mountain settings. PMID:15707037

Daly, Gillian L; Wania, Frank

2005-01-15

437

Synergetic Antimicrobial Effects of Mixtures of Ethiopian Honeys and Ginger Powder Extracts on Standard and Resistant Clinical Bacteria Isolates  

PubMed Central

Purpose. To evaluate antimicrobial effects of mixtures of Ethiopian honeys and ginger rhizome powder extracts on Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922), Staphylococcus aureus (MRSA), Escherichia coli (R), and Klebsiella pneumoniae (R). Methods. Agar diffusion and broth assays were performed to determine susceptibility of these standard and resistant clinical bacteria isolates using honey-ginger powder extract mixtures. Results. Honey-ginger powder extract mixtures produced the highest mean inhibition (25.62?mm ± 2.55) compared to the use of honeys (21.63?mm ± 3.30) or ginger extracts (19.23?mm ± 3.42) individually. The ranges of inhibitions produced by honey-ginger extract mixtures on susceptible test organisms (26–30?mm) and resistant strains (range: 19–27?mm) were higher compared to 7–22?mm and 0–14?mm by standard antibiotic discs. Minimum inhibitory concentrations (MIC) of mixture of honeys-ginger extracts were 6.25% (0.625?v/mL) on the susceptible bacteria compared to 75% for resistant clinical isolates. Minimum bactericidal concentration (MBC) of honey-ginger extracts was 12.5% (0.125?g/mL) for all the test organisms. Conclusion. The result of this study showed that honey-ginger powder extract mixtures have the potential to serve as cheap source of antibacterial agents especially for the drug resistant bacteria strains. PMID:24772182

Ewnetu, Yalemwork; Lemma, Wossenseged; Birhane, Nega

2014-01-01

438

Investigation of organic systems by ion-photon spectroscopy  

NASA Astrophysics Data System (ADS)

We study spectral composition, quantum yield and spatial intensity distribution of radiation of excited particles, escaping from the surface of some organic dyes and their mixtures with lipids under bombardment by Ar+ ions. Essential influence of the method of target preparation from organic compounds on the yield of the excited particles is demonstrated. The processes resulting in formation of excited particles under ion bombardment of complex organic systems are specified. The model of interaction of lipids with organic dyes is proposed.

Afanas'eva, I. A.; Bobkov, V. V.; Gritsyna, V. V.; Shevchenko, D. I.

2011-06-01

439

Characterization of Interstellar Organic Molecules  

SciTech Connect

Understanding the origins of life has been one of the greatest dreams throughout history. It is now known that star-forming regions contain complex organic molecules, known as Polycyclic Aromatic Hydrocarbons (PAHs), each of which has particular infrared spectral characteristics. By understanding which PAH species are found in specific star-forming regions, we can better understand the biochemistry that takes place in interstellar clouds. Identifying and classifying PAHs is not an easy task: we can only observe a single superposition of PAH spectra at any given astrophysical site, with the PAH species perhaps numbering in the hundreds or even thousands. This is a challenging source separation problem since we have only one observation composed of numerous mixed sources. However, it is made easier with the help of a library of hundreds of PAH spectra. In order to separate PAH molecules from their mixture, we need to identify the specific species and their unique concentrations that would provide the given mixture. We develop a Bayesian approach for this problem where sources are separated from their mixture by Metropolis Hastings algorithm. Separated PAH concentrations are provided with their error bars, illustrating the uncertainties involved in the estimation process. The approach is demonstrated on synthetic spectral mixtures using spectral resolutions from the Infrared Space Observatory (ISO). Performance of the method is tested for different noise levels.

Gencaga, Deniz; Knuth, Kevin H. [University at Albany, Department of Physics, Albany, NY (United States); Carbon, Duane F. [NASA Ames Research Center, NASA Advanced Supercomputing Division, Moffett Field, CA (United States)

2008-11-06

440

Pyrolysis Mass Spectrometry of Complex Organic Materials.  

ERIC Educational Resources Information Center

Illustrates the state of the art in pyrolysis mass spectrometry techniques through applications in: (1) structural determination and quality control of synthetic polymers; (2) quantitative analysis of polymer mixtures; (3) classification and structural characterization of fossil organic matter; and (4) nonsupervised numerical extraction of…

Meuzelaar, Henk L. C.; And Others

1984-01-01

441

Solvent Selection Use dry ice/isopropanol for cooling baths  

E-print Network

for single- solvent systems, azeotropes, and solvent mixtures with >10°C difference in boiling point. Use, or for high-boiling liquids simply use air. Use Dry Column Vacuum Chromatography to purify large samples

Chan, Hue Sun

442

Assessment of nutrient availability from organic wastes use in agriculture. A review  

Microsoft Academic Search

Organic wastes are products which, firstly, are wastes and secondly contain organic compounds, i.e. organic C and N. Except for some special organic industrial by-products, these wastes, which are farmyard manure, poultry manure, pig and cattle slurries, sewage sludges, compost and mixtures of these by- products, are derived from living processes. Therefore they contain all elements that are found in

Jean-Claude Fardeau

443

Current Applications of Gas Chromatography\\/Mass Spectrometry in the Study of Organic Acids in Urine  

Microsoft Academic Search

Gas chromatography\\/mass spectrometry (GC\\/MS) is the most suitable technique for the diagnosis of disorders of organic acid metabolism, known as organic acidurias. They are inherited metabolic disorders that are characterized by an excessive amount of organic acids and their metabolites. Now in many clinical and diagnostic laboratories, automated, quantitative, and qualitative procedures for complex mixture analysis of urinary organic acids

Joanna Kauna-Czapli?ska

2011-01-01

444

Perceptual Interactions in Odour Mixtures: Odour Quality in Binary Mixtures of Woody and Fruity Wine Odorants  

Microsoft Academic Search

The qualitative perceptual interactions in three binary mixtures of wine odorants were studied: isoamyl acetate (fruity note)\\/ whisky lactone (woody note), ethyl butyrate (fruity note)\\/whisky lactone (woody note) and ethyl butyrate (fruity note)\\/guaiacol (woody note). For each binary mixture, the perceived quality and intensity of 24 stimuli (four supra-threshold concentration levels of each of the two compounds and their 16

Boriana Atanasova; Thierry Thomas-Danguin; Claire Chabanet; Dominique Langlois; Sophie Nicklaus; Patrick Etievant

2005-01-01

445

Laboratory evaluation of crumb rubber asphalt concrete mixtures using the concepts of SMA mixtures  

E-print Network

LABORATORY INVESTIGATION 35 Testing Program . Preparation of the Samples Preconditioning of the Test Specimens Testing of the Samples . V DISCUSSION OF TEST RESULTS AND PERFORMANCE EVALUATION 39 39 43 45 48 Resilient Modulus Indirect Tensile... Procedure 36 38 Page FIGURE 5. 1 Control and CRM Mixtures - AAMAS Chart for Resilient Modulus Vs. Temperature 50 FIGURE 5. 2 Indirect Tensile Strength and Strain Data for CRM and Control Mixtures @77F 53 FIGURE 5. 3 Indirect Tensile Strength...

Rebala, Somasekhar Reddy

1994-01-01

446

The development and application of the chemical mixture methodology in analysis of potential health impacts from airborne release in emergencies  

SciTech Connect

The Chemical Mixture Methodology (CMM) is used for emergency response and safety planning by the U.S. Department of Energy, its contractors, and other private and public sector organizations. The CMM estimates potential health impacts on individuals and their ability to take protective actions as a result of exposure to airborne chemical mixtures. They are based on the concentration of each chemical in the mixture at a designated receptor location, the protective action criteria (PAC) providing chemical-specific exposure limit values, and the health code numbers (HCNs) that identify the target organ groupings that may be impacted by exposure to each chemical in a mixture. The CMM has been significantly improved since its introduction more than 10 years ago. Major enhancements involve the expansion of the number of HCNs from 44 to 60 and inclusion of updated PAC values based on an improved development methodology and updates in the data used to derive the PAC values. Comparisons between the 1999 and 2009 versions of the CMM show potentially substantial changes in the assessment results for selected sets of chemical mixtures. In particular, the toxic mode hazard indices (HIs) and target organ HIs are based on more refined acute HCNs, thereby improving the quality of chemical consequence assessment, emergency planning, and emergency response decision making. Seven hypothetical chemical storage and processing scenarios are used to demonstrate how the CMM is applied in emergency planning and hazard assessment.

Yu, Xiao-Ying; Petrocchi, Achille J.; Craig, Douglas K.; Glantz, Clifford S.; Trott, Donna M.; Ciolek, John T.; Lu, Po-Yung; Bond, Jayne-Anne; Tuccinardi, Thomas E.; Bouslaugh, Philip R.

2010-07-15

447

Organ History  

NSDL National Science Digital Library

Developed and maintained by Professor James H. Cook at Birmingham - Southern College, this site is an online tutorial that offers an interesting and interactive perspective of that king of all instruments, the organ. The site is divided into three main sections: The Organ and How it Works, Organ History, and Geographical Tour. In the first section, visitors are taken through a basic description of an organ, which then continues into a discussion of the various parts of an organ, such as the keyboards, consoles, pipes, chests, cases, and chambers. The history section begins with the invention of what is commonly understood to be the first organ, the ktseibios, built by a Greek engineer working in the third century BCE. The final section takes visitors on a chronological tour of the organ and its development throughout a number of countries, including England, France, Germany, Italy, and the United States.

Cook, James H.

448

SORPTION AND TRANSPORT OF HYDROPHOBIC ORGANIC CHEMICALS IN AQUEOUS AND MIXED SOLVENT SYSTEMS: MODEL DEVELOPMENT AND PRELIMINARY EVALUATION  

EPA Science Inventory

A theoretical approach, based upon the assumption of predominance of solvophobic interactions, was formulated to quantitatively describe the sorption and transport of hydrophobic organic chemicals (HOC) from aqueous and aqueous-organic-solvent mixtures. In the theoretical approac...

449

EXTRACTION OF TITANIUM(IV) BY MIXTURES OF MONO AND DH(2-ETHYLHEXYL) PHOSPHORIC ACID ESTERS  

Microsoft Academic Search

Solvent extraction of titanium(IV) from hydrochloric acid solutions by mixtures of mono- and di-2-ethylhexyl phosphoric acid esters (MEHPA and DEHPA) has been investigated as a function of HC1 concentration in the aqueous phase and extractants concentration in the organic phaseIt was found that MEHPA extracts Ti, 3 orders of magnitude more efficiently than DEHPA. Efficiency of extraction by MEHPA does

Vladimir Kislik; Aharon Eyal

1993-01-01

450

Effects of biologically-active chemical mixtures on fish in a wastewater-impacted urban stream  

Microsoft Academic Search

Stream flow in urban aquatic ecosystems often is maintained by water-reclamation plant (WRP) effluents that contain mixtures of natural and anthropogenic chemicals that persist through the treatment processes. In effluent-impacted streams, aquatic organisms such as fish are continuously exposed to biologically-active chemicals throughout their life cycles. The North Shore Channel of the Chicago River (Chicago, Illinois) is part of an

Larry B. Barber; Gregory K. Brown; Todd G. Nettesheim; Elizabeth W. Murphy; Stephen E. Bartell; Heiko L. Schoenfuss

2011-01-01

451

Mutagenic activity of ultraviolet-irradiated mixtures of nitrogen dioxide and propene or butadiene  

Microsoft Academic Search

The mutagenic activities of mixtures of nitrogen dioxide and 1,3-butadiene or propene were investigated after uv-irradiation in a small, laboratory-bench scale flow-through gas exposure system. The tester organism was Salmonella typhimurium, principally strain TA100. The photoreaction products from 1,3-butadiene and nitrogen dioxide were more mutagenic than those from propene and nitrogen dioxide. Approximately 0.25 ppm butadiene, compared to 100 ppm

K. Victorin; M. Stahlberg

1989-01-01

452

Energy and exergy analysis of an efficient organic Rankine cycle for low temperature power generation  

Microsoft Academic Search

This paper presents and discusses the performance of an advanced Organic Rankine Cycle (ORC) using a heated chemical instead of steam as found in the typical Rankine Cycle. Chemicals used are the new quaternary refrigerant mixtures that are environmentally-friendly and have efficient thermodynamic properties at low and medium waste heat temperatures compared to other organic and non-organic fluids.This mixture boils

S. M. Sami

2008-01-01

453

Boson-boson mixtures and triplet correlations  

NASA Astrophysics Data System (ADS)

The hypernetted-chain formalism for boson-boson mixtures described by an extended Jastrow correlated wave function is derived, taking into account elementary diagrams and triplet correlations. The energy of an ideal boson 3He-4He mixture is computed for low values of the 3He concentration. The zero-3He-concentration limit provides a 3He chemical potential in good agreement with the experimental value, when a McMillan two-body correlation factor and the Lennard-Jones potential are adopted. If the Euler equations for the two-body correlation factors are solved in presence of triplet correlations, the agreement is again improved. At the experimental 4He equilibrium density, the 3He chemical potential turns out to be -2.58 K, to be compared with the experimental value, -2.79 K.

Fabrocini, A.; Polls, A.

1984-08-01

454

Heavy-light fermion mixtures at unitarity  

SciTech Connect

We investigate fermion pairing in the unitary regime for a mass ratio corresponding to a {sup 6}Li-{sup 40}K mixture using quantum Monte Carlo methods. The ground-state energy and the average light- and heavy-particle excitation spectrum for the unpolarized superfluid state are nearly independent of the mass ratio. In the majority light system, the polarized superfluid is close to the energy of a phase separated mixture of nearly fully polarized normal and unpolarized superfluid. For a majority of heavy particles, we find an energy minimum for a normal state with a ratio of {approx}3:1 heavy to light particles. A slight increase in attraction to k{sub F}a{approx}2.5 yields a ground state energy of nearly zero for this ratio. A cold unpolarized system in a harmonic trap at unitarity should phase separate into three regions, with a shell of unpolarized superfluid in the middle.

Gezerlis, Alexandros [Los Alamos National Laboratory; Carlson, Joseph [Los Alamos National Laboratory; Gandol, S [UNIV. ILL; Schmidt, E [ITALY

2009-01-01

455

Embedded Electronic Nose for VOC Mixture Analysis  

SciTech Connect

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.

Botre, B.; Gharpure, D.; Shaligram, A. [Department of Electronic Science, University of Pune, Pune: 411007 (India)

2009-05-23

456

UV sensors based on liquid crystals mixtures  

NASA Astrophysics Data System (ADS)

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.

Chanishvili, Andro; Petriashvili, Gia; Chilaya, Guram; Barberi, Riccardo; De Santo, Maria P.; Matranga, Mario A.; Ciuchi, F.

2006-04-01

457

NMRI Measurements of Flow of Granular Mixtures  

NASA Technical Reports Server (NTRS)

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.

Nakagawa, Masami; Waggoner, R. Allen; Fukushima, Eiichi

1996-01-01

458

Fluctuating hydrodynamics of multispecies reactive mixtures  

E-print Network

We formulate and study computationally the fluctuating compressible Navier-Stokes equations for reactive multi-species fluid mixtures. We contrast two different expressions for the covariance of the stochastic chemical production rate in the Langevin formulation of stochastic chemistry, and compare both of them to predictions of the chemical Master Equation for homogeneous well-mixed systems close to and far from thermodynamic equilibrium. We develop a numerical scheme for inhomogeneous reactive flows, based on our previous methods for non-reactive mixtures [K. Balakrishnan, A. L. Garcia, A. Donev and J. B. Bell, Phys. Rev. E 89:013017, 2014]. We study the suppression of non-equilibrium long-ranged correlations of concentration fluctuations by chemical reactions, as well as the enhancement of pattern formation by spontaneous fluctuations. Good agreement with available theory demonstrates that the formulation is robust and a useful tool in the study of fluctuations in reactive multi-species fluids. At the same...

Bhattacharjee, A K; Donev, A; Garcia, A L; Bell, J B

2015-01-01

459

Mixture Hidden Markov Models in Finance Research  

NASA Astrophysics Data System (ADS)

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.

Dias, José G.; Vermunt, Jeroen K.; Ramos, Sofia

460

Embedded Electronic Nose for VOC Mixture Analysis  

NASA Astrophysics Data System (ADS)

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.

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

2009-05-01

461

Comparison of species-rich cover crop mixtures in Hungarian vineyards  

NASA Astrophysics Data System (ADS)

In case of vine growing, agricultural practices of the past decades - as mechanical cultivation on steep vineyard slopes - can endanger the soil of vineyards. Moreover, climate change scenarios predict heavier rainstorms, which can also promote the degradation of the soil. These are some of the reasons why sustainable floor management plays an increasingly important role in viticulture recently. The use of cover crops in the inter-row has a special importance, especially on steep slopes and in case of organic farming to provide conditions for environmental friendly soil management. Species-rich cover crop seed mixtures may help to prevent erosion and create easier cultivation circumstances. Furthermore they have a positive effect on soil structure, soil fertility and ecosystem functions. However, it is important to find suitable seed mixtures for specific production sites, consisting ideally of native species from local provenance, adapted to the local climate/vine region/vineyard. Requirements for suitable cover crop species are as follows: they should save the soil from erosion and also from compaction caused by the movement of workers and machines, they should not compete significantly with the grapevines, or influence produce quality. We started to develop and apply several species-rich cover crop seed mixtures in spring 2012. During the experiments, three cover crop seed mixtures (Biocont-Ecovin mixture, mixture of legumes, mixture of grasses and herbs) were compared in vineyards of the Tokaj and Szekszárd vine regions of Hungary. Each mixture was sown in three consecutive inter-rows at each experimental site (all together 10 sites). Besides botanical measurements, yield, must quality, and pruning weight was studied in every treatment. The botanical survey showed that the following species of the mixtures established successfully and prospered during the years 2012 and 2013: Coronilla varia, Lotus corniculatus, Medicago lupulina, Onobrychis viciifolia, Plantago lanceolata, Trifolium pratense, Trifolium repens and Vicia sativa. We found that weed cover was lower in every treatment compared to the unsown control plots, thus, cover crops suppressed weeds of the inter-rows effectively. Most examined indices of grapevines were not significantly affected by the applied cover crop. However, the tendency of the results shows that in the drier climate of Hungary every second inter-row sowing is more preferable than consecutive cover-crop application, where erosion control is not essential. The opinion of the growers about the mixtures varied. The Biocont-Ecovin mixture was praised for its early aesthetic qualities, produced by Camelina sativa, Phacelia tanacetifolia and Sinapis alba. However, it was criticized for its non-native species, the foreign provenance of some seeds, and the height of the vegetation. The other two mixtures did not produce a spectacular flowering, but developed a lower canopy, and were praised for their native species content. Due to spring sowing the grass-herb mixture, containing a number of species with autumn germination, produced the lowest coverage among the tested mixtures in the first year. However, as predicted, it performed satisfactorily in the second year of the trial. The interest of the vine-growers underlines the importance of the topic for the Central-Eastern European region, thus further examination will be continued in 2014.

Donkó, Adam; Miglécz, Tamas; Valkó, Orsolya; Török, Peter; Deák, Balazs; Kelemen, Andras; Zanathy, Gabor; Drexler, Dora

2014-05-01

462

Electron Swarm Coefficients in – and – Mixtures  

Microsoft Academic Search

The electron swarm coefficients (i.e., drift velocity, longitudinal diffusion coefficient, and effective ionization coefficient) have been measured using a time-resolved pulsed Townsend technique in O2, N2, and CO2 and their mixtures CO2-N2 and CO2-O2, with CO2 shares of 20%, 50%, and 80%. Simultaneously, these swarm data have been calculated from an adequate multiterm solution of the Boltzmann equation, using previously

Mohammed Yousfi; Jaime de Urquijo; Antonio Juárez; Eduardo Basurto; Jose Luis Hernández-Ávila

2009-01-01

463

Dielectric relaxation of acetonitrile-water mixtures  

Microsoft Academic Search

The dielectric relaxation of acetonitrile-water mixtures is measured at 298.15 K. From the resulting complex permittivity spectra, two relaxation processes are found. The low-frequency process is attributed to water molecules that reside in a micro-phase of relatively stable clusters. The high-frequency process is attributed to both acetonitrile and water molecules in a second micro-phase. The divergence of the structure of

R. Jellema; J. Bulthuis; G. van der Zwan

1997-01-01

464

Instability of a solidifying binary mixture  

NASA Technical Reports Server (NTRS)

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.

Antar, B. N.

1982-01-01

465

Analysis of exponential decay curves of mixtures  

E-print Network

INTRODUCTION The object of this research was to determine the efficiency and accuracy of a method of analyzing exponential decay curves of radio- active mixtures by applying linear programming solutions to Prony's method. This research is an extension of a... programs were written to utilize the RAND X028 SIMPLEX subroutine and the CEIR LP/90 system in solving the problem. CHAPTER I I LINEAR PROGRAMMING The general linear programming problem is to minimize some linear objective function, subject to a set...

McGaughey, Robert Lee

1967-01-01

466

Shear viscosity of hadronic gas mixtures  

E-print Network

We investigate the effects of baryon chemical potential \\mu on the shear viscosity coefficient \\eta and the viscosity to entropy density ratio \\eta/s of a pion-nucleon gas mixture. We find that \\eta is an increasing function of T and \\mu, while the ratio \\eta/s turn