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1

Near azeotropic mixture substitute  

NASA Technical Reports Server (NTRS)

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

Jones, Jack A. (Inventor)

1996-01-01

2

Nearly Azeotropic Mixtures To Replace Refrigerant 12  

NASA Technical Reports Server (NTRS)

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

Jones, Jack A.

1992-01-01

3

Pervaporation and vapor permeation at the azeotropic point or in the vicinity of the LLE boundary phases of organic\\/aqueous mixtures  

Microsoft Academic Search

Pervaporation and vapor permeation experiments have been performed in order to investigate separately the effect of feed density and concentration on the material transport from the bulk feed to the bulk permeate. Measurements have been carried out for the azeotropic mixtures ethanol\\/water, 1,4-dioxane\\/water and 2-propanol\\/water at 333 and 353 K using a hydrophilic PVA\\/PAN-composite-membrane. In particular the influence of the

M. S. Schehlmann; E. Wiedemann; R. N. Lichtenthaler

1995-01-01

4

Near azeotropic mixture substitute for dichlorodifluoromethane  

NASA Technical Reports Server (NTRS)

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

Jones, Jack A. (Inventor)

1998-01-01

5

Near azeotropic mixture substitute for dichlorodifluoromethane  

NASA Technical Reports Server (NTRS)

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

Jones, Jack A. (Inventor)

1996-01-01

6

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.

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

2010-01-01

7

Addition of an azeotropic ETBE\\/ethanol mixture in eurosuper-type gasolines  

Microsoft Academic Search

This study proposes an azeotropic ETBE\\/ethanol mixture as a possible oxygenated additive for the formulation of eurosuper-type gasolines. Two eurosuper gasolines with different chemical compositions and well defined characteristics of density, volatility and octane numbers are used. Gasoline formulations containing azeotropic mixtures display an intermediary behavior between that of ETBE (ethyl tert-butyl ether) and ethanol in gasoline blends. Formulations containing

Eliana Weber de Menezes; Renato Cataluña; Dimitrios Samios; Rosângela da Silva

2006-01-01

8

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

NASA Astrophysics Data System (ADS)

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

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

9

Efficiency of vapor compression heat pumps based on non-azeotropic refrigerant mixtures  

NASA Astrophysics Data System (ADS)

The work presents the results of cycle computation for vapor compression pumps based on ozone-safe mixed refrigerants. Non-azeotropic binary refrugerants R32/R152a (30/70) and R32/R134a (30/70) were considere as working substances. Properties of non-azeotropic refrigerants were calculated according to the additivity method of thermodynamic functions and method of Lemmon and Jacobsen. Deviations in the values of thermophysical properties obtained with two methods have been determined. It is shown that at the use of nonazeotropic mixture R32/R152a (30/70), energy conversion ratio increases by 2.2-3.6 % compared with the results for R32/R134a (30/70) at temperature difference between the processes of boiling and condensation from 28 to 53 °C.

Mezentseva, N. N.

2011-06-01

10

Separation of azeotropic mixture using modified PVA membrane  

Microsoft Academic Search

Polyvinyl alcohol (PVA) membrane (4wt.%) was modified by lithium chloride (0.05–0.2wt.%) to investigate the effect of addition of alkali salt on separation of water–isopropyl alcohol mixture. The surface of casted membranes was subsequently cross-linked by exposure to low-pressure nitrogen plasma. The separation performance of modified membrane was analyzed by pervaporation technique at 25°C, showing improvement in the flux and the

D. J. Upadhyay; N. V. Bhat

2005-01-01

11

Heat transfer in pool boiling of binary and ternary non-azeotropic mixtures  

NASA Astrophysics Data System (ADS)

Heat transfer coefficients in nucleate pool boiling of binary and ternary non-azeotropic hydrocarbon mixtures were obtained experimentally using a vertical electrically heated cylindrical carbon steel surface at atmospheric pressure with several surface roughness. The fluids used were Methanol/1-Pentanol and Methanol/1-Pentanol/1,2-Propandiol at constant 1,2-Propandiol mole fraction of 30%. Heat fluxes were varied in the range 25-235 kW/m2. The cylindrical heater surface was polished to an average surface roughness of 0.2 ?m, and sandblasted yielding surface roughness of 2.98 and 4.35 ?m, respectively. The experimental results were compared to available prediction correlations, indicating that the correlations based on the boiling range are in better qualitative agreement than correlations based on the phase envelope. Increasing surface roughness resulted in an increase in the heat transfer coefficient, and the effect was observed to be dependent on the heat flux and fluid composition.

Nahra, Ziad; Næss, Erling

2009-05-01

12

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

Microsoft Academic Search

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.

Xin Liu

1996-01-01

13

Performance of Pentaborane, Pentaborane - JP-4 Fuel Mixtures, and Trimethylborate Azeotrope Fuel in a Full-Scale Turbojet Engine  

NASA Technical Reports Server (NTRS)

This report summarizes the full-scale engine tests of pentaborane, pentaborane - JP-4 fuel mixtures, and trimethylborate azeotrope fuel. The tests were conducted in a full-scale turbojet engine at a simulated altitude of 50,000 feet and Mach number of 0.08. Engine speeds were 90 to 100 percent of rated speed. Pentaborane reduced the the specific fuel consumption to two-thirds that of JP-4 fuel. However, because boron oxide collected in the engine, the performance deteriorated with continued operation of pentaborane in each of the short-duration tests reported.

Breitwiesser, Roland; Useller, James W.

1956-01-01

14

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...

15

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

16

Experimental Determination of Forced Convection Evaporative Heat Transfer Coefficients for Non-Azeotropic Refrigerant Mixtures.  

National Technical Information Service (NTIS)

A number of experiments were conducted in the 1960's to determine the two phase heat transfer coefficient, h TP of pure refrigerants. Recently energy conservation requirements spurred interest in nonazeotropic refrigerant mixtures, because such mixtures c...

D. Didion H. Ross R. Radermacher

1983-01-01

17

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

18

Variation of Azeotropic Composition and Temperature with Pressure  

ERIC Educational Resources Information Center

Describes an undergraduate physical chemistry experiment in which an azeotropic mixture is studied using the vapor pressures of the components as functions of temperature and the azeotropic composition and temperature at one pressure. Discusses in detail the mathematical treatment of obtained thermodynamic data. (MLH)

Gibbard, H. Frank; Emptage, Michael R.

1975-01-01

19

Experimental and theoretical study on flow condensation with non-azeotropic refrigerant mixtures of R32\\/R134a  

Microsoft Academic Search

Experiments on flow condensation have been conducted with both pure R32, R134a and their mixtures inside a tube (10 m long, 6 mm ID), with a mass flux of 131–369 kg m?2s?1 and average condensation temperature of 23–40°C. The experimental heat transfer coefficients are compared with those predicted from correlations. The maximum mean heat transfer coefficient reduction (from a linear

D. W Shao; E Granryd

1998-01-01

20

Synthesis of azeotropic batch distillation separation systems  

SciTech Connect

The sequencing of batch distillation systems, in particular batch distillation columns, can be complicated by the existence of azeotropes in the mixture. These azeotropes can form batch distillation regions where, depending on the initial feed to the batch column, the types of feasible products and separations are limited. It is very important that these distillation regions are known while attempting to synthesize sequences of batch columns so infeasible designs can be eliminated early on in the design phase. The distillation regions also give information regarding the feasible products that can be obtained when the mixture is separated by using a variety of batch column configurations. The authors will show how a tool for finding the batch distillation regions of a particular mixture can be used in the synthesis of batch distillation column sequences. These sequences are determined by the initial feed composition to the separation network. The network of all possible sequences will be generated by using state-task networks when batch rectifying, stripping, middle vessel, and extractive middle vessel columns are allowed. The authors do not determine which sequence is the best, as the best sequence will depend on the particular application to which one is applying the algorithms. They show an example problem for illustration of this technique.

Safrit, B.T. [Eastman Chemical Co., Kingsport, TN (United States)] [Eastman Chemical Co., Kingsport, TN (United States); Westerberg, A.W. [Carnegie Mellon Univ., Pittsburgh, PA (United States)] [Carnegie Mellon Univ., Pittsburgh, PA (United States)

1997-05-01

21

Study to determine the existence of an azeotropic R-22 `drop-in` substitute  

SciTech Connect

The reduction in chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC) production and the scheduled phase-out of these ozone depleting refrigerants requires the development and determination of environmentally safe refrigerants for use in heat pumps, water chillers, air conditioners, and refrigerators. Azeotropic mixtures are attractive as alternative refrigerants because they behave very nearly as pure materials. A simple correlative scheme that allows one to judge whether or not an azeotrope is likely in a binary refrigerant mixture is discussed. This paper presents laboratory and computer simulation model evaluation of two of the azeotropic refrigerant mixtures which are identified, HFC-134a (1,1,1,2-tetrafluoroethane) with R-C290 (Propane) and HFC-134a with R-600a (Isobutane), in a generic heat pump apparatus. A third azeotropes mixture, HFC-134a with R-C290 (Cyclopropane) is examined by computer simulation only.

Kim, M.S.; Morrison, G.; Mulroy, W.J.; Didion, D.A.

1996-03-01

22

Solubility of organic mixtures in water  

SciTech Connect

The solubilities of several chlorobenzenes and other mixtures in water have been determined. The results varied with the phase of the solute mixture and the hydrophilicity of the components and were interpreted through activity coefficients calculated by the UNIFAC equation. It was found that mixtures of structurally related hydrophobic liquids were near ideal in the organic phase; in the aqueous phase activity coefficient of a component was unaffected by the presence of consolutes. Increasing hydrophilicity of the solutes lead to deviations from ideality in the organic phase, but these could be largely accounted for by the UNIFAC equation. For mixtures of solids which did not interact, the components tended to behave independently of one another, and their solubilities were approximately additive. The behavior of mixtures of liquids and solids was intermediate between that of liquid mixtures and that of mixtures of solids. The application of these results to the toxicity of organic mixtures in water is discussed.

Banerjee, S.

1984-08-01

23

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

24

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 C and a pressure of at least about 1,500 psi. The separation solution is then contacted with the organic mixtures while maintaining the temperature and pressure as above until the mixtures and solution reach equilibrium to extract the preselected low molecular weight components from the organic mixtures. Finally, the entrainer/extracted components portion of the equilibrium mixture is isolated from the separation solution. 1 fig.

Chum, H.L.; Filardo, G.

1990-10-23

25

RELIABLE COMPUTATION OF HOMOGENEOUS AZEOTROPES. (R824731)  

EPA Science Inventory

Abstract It is important to determine the existence and composition of homogeneous azeotropes in the analysis of phase behavior and in the synthesis and design of separation systems, from both theoretical and practical standpoints. A new method for reliably locating an...

26

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

27

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

28

PERVAPORATIVE REMOVAL OF VOLATILE ORGANIC COMPOUNDS FROM MULTICOMPONENT AQUEOUS MIXTURES  

Microsoft Academic Search

The present study concerns with the separation of binary and ternary water–organics mixtures by pervaporation using different organophilic membranes (i.e., PERVAP-1060—polydimethylsiloxane, PERVAP-1070—zeolite filled polydimethylsiloxane, PEBAX-4033—polyether block amide). The following binary and ternary liquid mixtures were investigated: water–methyl acetate; water–ethyl acetate; water–butyl acetate, water–methyl t-butyl ether (MTBE), and water–methanol–MTBE. The organic components of these mixtures can be found in the wastewaters

Wojciech Kujawski; Renata Roszak

2002-01-01

29

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...

30

SECONDARY ORGANIC AEROSOL FORMATION FROM MIXTURES OF BIOGENIC HYDROCARBONS  

EPA Science Inventory

In this work the influence of hydrocarbon mixtures on the overall Secondary Organic Aerosol yield is investigated. Photochemical reaction experiments were conducted using mixtures of a-pinene, isoprene and propene in the presence of NOx. Results of the experiments show...

31

Predicting microbial toxicity of nonuniform multicomponent mixtures of organic chemicals  

SciTech Connect

Three schemes proposed in the literature for analyzing joint toxic effects of multicomponent mixtures on fish, namely the additivity index (AI), the mixture toxicity index (MTI), and the similarity parameter ({lambda}) are evaluated in this study for microbial toxicity. A new approach is proposed to establish acceptance limits for the similarity parameter, {lambda}, based on experimental errors and uncertainties. Quantitative structure activity relationship (QSAR) techniques are then used to develop a model to predict the concentrations of components in mixtures that would jointly cause 50% inhibition of microbial respiration. The application of this approach is demonstrated on the experimental toxicity data of six eight-component organic chemical mixtures on microorganisms.

Peace, J. [Phelps Dodge Tyrone Inc., Tyrone, NM (United States); Daniel, D.; Nirmalakhandan, N.; Egemen, E. [New Mexico State Univ., Las Cruces, NM (United States)

1997-04-01

32

Acoustic properties of organic acid mixtures in water  

NASA Technical Reports Server (NTRS)

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

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

1974-01-01

33

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...

34

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

SciTech Connect

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

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

1995-03-01

35

Biodegradation of trace levels of a complex organic pollutant mixture.  

PubMed

Three bacterial isolates with the ability to grow on a model mixture of ground water contaminants were obtained from a sewage works for treatment of industrial effluents, and from heavily and intermediately contaminated ground. The mixture consisted of benzene, toluene, o-xylene, nitrobenzene, 1,4-dichlorobenzene, o-cresol, naphthalene, tetrachloromethane and trichloroethylene, at concentrations ranging from 150 to 600 micrograms/l (2.1 mg/l in total). A supplement of 50 mg/l phenol was added to support growth and batch cultures were adapted for 6 weeks. Preliminary assays to check for degradative ability and toxicological assessments of the compounds using oxygen uptake rates were undertaken. Each isolate exhibited a different extent of degradation for the compounds. In 18 h incubation, from an initial figure of 1,966 micrograms/l (not including the primary substrate) the highest remaining total organic carbon of 800 micrograms/l was for the isolate from activated sludge. The effect of the organic compounds upon oxygen uptake rate was less marked for the micro-organisms from heavily polluted ground. As far as bioremediation of groundwater is concerned, the combination of both chemical structure variety and extremely low concentrations of individual chemicals in the mixture under investigation, make the present report relevant to many environmental problems. PMID:8078413

Limbert, E S; Betts, W B

1994-01-01

36

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

37

Flammability limits of fuel/fluorocarbon azeotropes  

SciTech Connect

Both Dehn and Thorne have intimated that flash point (FP) measurements could be used to define the gas-phase flammability limits of fire and retardant vapor mixtures above the surface of heated retardant containing flammable liquids. However, it was found that ignitable mixtures exist above the liquid surface, where the concentration of the agent in the fluid is well beyond the limiting concentrating for inerting of alcohol fires. Clearly this anomaly results from diffusion competition of air and liquid vapor mixture at the position of the ignitor, as influenced by the design of the experimental apparatus. The authors are skeptical about the need or worth of attempting to define flammability limits using FP data, especially since unknown variables control the response. More important is to define the concentration of liquid phase retardant that will affect gas phase inerting. Thus, it is necessary to continue practical testing of retardant-containing liquids for their effectiveness in mitigating possible accidents, e.g., the next phase of this work will assess the effectiveness of halocarbons to inert high-pressure alcohol/agent leaks impinging on both electrical and flame ignition sources.

Alvares, N.J.; Hammond, P.R.; Foote, K.; Ford, H.W. Jr.

1981-02-10

38

THERMODYNAMIC EVALUATION OF PREDICTED FLUORINATED ETHER, ETHANE, AND PROPANE AZEOTROPES  

EPA Science Inventory

The paper gives results of thermodynamic analyses, using basic thermophysical property data, to evaluate seven predicted fluorinated ether, ethane, and propane azeotropes: E125/RC270, E125/R134a, E143a/R134, R134a/E143a, E143a/ R152a, R134/R245cb, and R245cb/R227ea. he performanc...

39

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 ...

40

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 30cm×30cm 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

41

Solubility, sorption, and transport of hydrophobic organic chemicals in complex mixtures. Environmental research brief  

Microsoft Academic Search

Environmental contamination problems commonly involve wastes consisting of complex mixtures of chemicals. The behavior of these mixtures has not been well understood because the primary chemodynamic properties of organic chemicals have usually been characterized in aqueous solutions which are simple in composition relative to many waste mixtures found at or near disposal\\/spill sites. The research summarized in the report focuses

P. S. C. Rao; L. S. Lee; A. L. Wood

1991-01-01

42

Quantitative Analysis of MR Brain Image Sequences by Adaptive Self-Organizing Finite Mixtures  

Microsoft Academic Search

This paper presents an adaptive structure self-organizing finite mixture network for quantification of magnetic resonance (MR) brain image sequences. We present justification for the use of standard finite normal mixture model for MR images and formulate image quantification as a distribution learning problem. The finite mixture network parameters are updated such that the relative entropy between the true and estimated

Yue Wang; Tülay Adali; Chi-ming Lau; Sun-yuan Kung

1998-01-01

43

Comparative study of two phase flow boiling of refrigerant mixtures and pure refrigerants inside enhanced surface tubing  

SciTech Connect

In this paper, the characteristics of two phase flow boiling of pure refrigerant; R-22 as well as non-azeotropic refrigerant mixtures R-22/R-114 and R-22/R-152a inside horizontal enhanced surface tubing is presented. Correlations were proposed to predict the heat transfer characteristics of non-azeotropic refrigerant mixture flow boiling inside enhanced surface tubing. In addition, it was found that the enhancement of the heat transfer coefficient is dependent on the mixture components and their concentrations.

Sami, S.M.; Schnotale, J. (Mechanical Engineering, School of Engineering, Univ. of Moncton, Moncton, New Brunswick E1A 3E9 (CA))

1992-01-01

44

Mixtures of organic macrocycles for applications in solar cell devices  

Microsoft Academic Search

In this paper we present spectroscopic and photoelectric studies of two families of macrocycles and their mixtures: phthalocyanines and naphthalocyanines complexed with various ions. The dyes are characterized by significant light absorption and each dye absorbs in a different spectral region and covers only a part of the solar light spectrum. The use of t he dyes mixture extends the

A. Boguta; D. Wróbel; T. J. Hoffmann; P. Mazurkiewicz

2003-01-01

45

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...

46

Mixtures  

NSDL National Science Digital Library

Mixtures allows exploration of percents through two piles of colored and uncolored chips. The user must decide how many chips to color to create the desired percentage of colored chips compared to the total pile. Mixtures is one of the Interactivate assessment explorers.

47

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

48

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

49

Performance of a new refrigeration cycle using refrigerant mixture R32\\/R134a for residential air-conditioner applications  

Microsoft Academic Search

In this paper, a new refrigeration cycle (NRC) using the binary non-azeotropic refrigerant mixture R32\\/R134a is presented, which can be an alternative refrigeration cycle applied in residential air-conditioner. In the NRC, refrigerant circuit of the evaporator is separated into two branches. Because the non-azeotropic mixture has the characteristic of temperature glide, an important benefit of such configuration is that the

Jianyong Chen; Jianlin Yu

2008-01-01

50

Mixture Effects in the Catalytic Oxidation of VOCs (Volatile Organic Compounds) in Air.  

National Technical Information Service (NTIS)

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 sc...

S. Gangwal K. Ramanathan P. Caffrey M. Mullins J. Spivey

1988-01-01

51

Imidazolium-organic solvent mixtures as electrolytes for lithium batteries  

Microsoft Academic Search

?-Butyrolactone (BL) has been mixed to the room temperature ionic liquid (RTIL) 1-butyl 3-methyl-imidazolium tetrafluoroborate (BMIBF4) (ratio: 3\\/2, v\\/v) in the presence of lithium tetrafluoroborate (LiBF4) for use as electrolyte in lithium-ion batteries. This mixture exhibits a larger thermal stability than the reference electrolyte EC\\/DEC\\/DMC (2\\/2\\/1)+LiPF6 (1M) and can be considered as a new RTIL as no free BL molecules

A. Chagnes; M. Diaw; B. Carré; P. Willmann; D. Lemordant

2005-01-01

52

Modeling and Computation of Thermodynamic Equilibrium for Mixtures of Inorganic and Organic Species  

NASA Astrophysics Data System (ADS)

A series of modules has been developed in the atmospheric modeling community to predict the phase transition, crystallization and evaporation of inorganic aerosols. Modules for the computation of the thermodynamics of pure organic-containing aerosols have been developed more recently; however, the modeling of aerosols containing mixtures of inorganic and organic compounds has gathered less attention. We present here a model (UHAERO), that is flexible, efficient and rigorously computes the thermodynamic equilibrium of atmospheric particles containing inorganic and organic compounds. It is applied first to mixtures of inorganic electrolytes and dicarboxylic acids, and then to thermodynamic equilibria including crystallization and liquid-liquid phase separation. The model does not rely on any a priori specification of the phases present in certain atmospheric conditions. The multicomponent phase equilibrium for a closed organic aerosol system at constant temperature and pressure and for specified feeds is the solution to the equilibrium problem arising from the constrained minimization of the Gibbs free energy. For mixtures of inorganic electrolytes and dissociated organics, organic salts appear at equilibrium in the aqueous phase. In the general case, liquid-liquid phase separations happen and electrolytes dissociate in both aqueous and organic liquid phases. The Gibbs free energy is modeled by the UNIFAC model for the organic compounds, the PSC model for the inorganic constituents and a Pitzer model for interactions. The difficulty comes from the accurate estimation of interactions in the modeling of the activity coefficients. An accurate and efficient method for the computation of the minimum of energy is used to compute phase diagrams for mixtures of inorganic and organic species. Numerical results show the efficiency of the model for mixtures of inorganic electrolytes and organic acids, which make it suitable for insertion in global three-dimensional air quality models. Preliminary results for mixtures of inorganic and organic species are presented and exhibit the influence of liquid phase separation on the salt cristallyzation.

Caboussat, A.; Amundson, N. R.; He, J.; Martynenko, A. V.; Seinfeld, J. H.

2007-05-01

53

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...

54

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...

55

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...

56

Sensory Eye Irritation in Humans Exposed to Mixtures of Volatile Organic Compounds  

Microsoft Academic Search

Eight subjects participated in a controlled eyes-only exposure study of human sensory irritation in ocular mucosal tissue. The authors investigated dose-response properties and the additive effects of three mixtures of volatile organic compounds. The dose-response relationships for these mixtures showed increases in response intensity as concentration increased. Replication of exposure did not result in significantly different dose- response relationships. Moreover,

Anne Hempel-Jørgensen; Sren K. Kjærgaard; Lars Mølhave; Kenneth H. Hudnell

1999-01-01

57

Organic and conventional management of mixtures of wheat and spring cereals  

Microsoft Academic Search

Cereal mixtures may provide both organic and conventional producers with a more sustainable approach in reducing weed pressure,\\u000a crop rotation flexibility, improved yield stability, buffering against pests and diseases, minimizing soil variability and\\u000a increasing animal feed value. We examined the response of small grain mixtures containing wheat, oats, barley and triticale\\u000a to varying degrees of natural competition and environmental stress

A. H. E. E. Kaut; H. E. Mason; A. Navabi; J. T. O’Donovan; D. Spaner

2008-01-01

58

Ionization constants for very weak organic acids in aqueous solution and apparent ionization constants for water in aqueous organic mixtures  

Microsoft Academic Search

A potentiometric method using a glass electrode has been applied to determination of apparent ionization constants for water in binary mixtures of water with tetrahydrofuran, methanol, 1,3-propanediol, glycerol, sucrose, and glucose at 25°C. Further calculations with these apparent ionization constants, which are now based explicitly on the previously implicit assumption that ionization of the organic component is negligible compared to

Earl M. Woolley; Jay Tomkins; Loren G. Hepler

1972-01-01

59

Effect of dissolved inorganic salts on the isothermal vapor–liquid equilibrium of the propionic acid–water mixture  

Microsoft Academic Search

Propionic acid–water is one of the minimum boiling point azeotropic binary mixtures. Alteration of the vapor–liquid equilibrium (VLE) by addition of inorganic salts is of interest, since it allows bypassing the azeotropic point due to salt-in and salt-out effects. The effect of NaCl, NH4Cl, CaCl2, and AlCl3 at salt concentrations of 1 m and the effect of NaCl molality (0.5–3

Fawzi Banat; Sameer Al-Asheh; Jana Simandl

2002-01-01

60

Reentrant conformation transition in poly( N, N-dimethylacrylamide) hydrogels in water–organic solvent mixtures  

Microsoft Academic Search

Conformational changes in poly(N,N-dimethylacrylamide) (PDMA) networks swollen in aqueous solutions of organic solvents are studied both experimentally and theoretically. PDMA hydrogels of various charge densities were prepared by free-radical crosslinking copolymerization. Swelling behavior of the hydrogels was investigated in aqueous organic solvent mixtures as functions of solvent species and the concentration. With increasing volume fraction ? of acetone, tetrahydrofuran, or

Nermin Orakdogen; Oguz Okay

2006-01-01

61

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

62

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.

Mazurek, Monica A

2002-01-01

63

Fourier transform Raman spectral measurements of powdered quaternary mixtures of organic compounds  

Microsoft Academic Search

Fourier transform Raman spectra of eight mixtures of four organic solids, namely dicyandiamide, melamine, acetamide and urea were measured. Matrices formed from these spectra were first subjected to singular value decomposition to obtain the right singular vectors. The right singular vectors were then subjected to blind source separation using band-target entropy minimization (BTEM), thus no a priori information (i.e. involving

Chilukoti Srilakshmi; Effendi Widjaja; Bruce G. Anderson; Marc Garland

2007-01-01

64

Experimental investigation of conventional control strategies for a heterogeneous azeotropic distillation column  

Microsoft Academic Search

In this work, a laboratory scale sieve plate distillation column was constructed to investigate the conventional control strategies of an isopropyl alcohol (IPA), cyclohexane (CyH) and water (H2O) heterogeneous azeotropic distillation column. Steady state process analysis showed that the optimal operation point should be located at a critical reflux, a transition point at which the distillation path switches from a

I-L Chien; C. J Wang; D. S. H Wong; C.-H Lee; S.-H Cheng; R. F Shih; W. T Liu; C. S Tsai

2000-01-01

65

Determination of benzene and toluene in soils and plant material by azeotropic distillation  

SciTech Connect

The suspected dumping of gasoline near a garden resulted in the need for a method that would measure trace amounts of benzene and toluene in both soil and plant samples. In this report the authors show that a method involving methanolic extraction and azeotropic distillation is a highly sensitive technique that eliminated the contamination of the GC column by non-volatile material.

Kozloski, R.P.

1985-01-01

66

Coupling reaction and azeotropic distillation for the synthesis of glycerol carbonate from glycerol and dimethyl carbonate  

Microsoft Academic Search

A new process, coupling reaction and azeotropic distillation was proposed for the synthesis of glycerol carbonate (GC) from glycerol (G) and dimethyl carbonate (DMC). The bench scale experimental investigation was systematically conducted for this new process. With calcium oxide (CaO) as the solid catalyst, the high yield of glycerol carbonate can be obtained at a low molar ratio of dimethyl

Jiabo Li; Tao Wang

2010-01-01

67

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

68

Fact or artifact: the representativeness of ESI-MS for complex natural organic mixtures.  

PubMed

Because mass spectrometers provide their own dispersion and resolution of analytes, electrospray ionization mass spectrometry (ESI-MS) has become a workhorse for the characterization of complex mixtures from aerosols to crude oil. Unfortunately, ESI mass spectra commonly contain multimers, adducts and fragments. For the characterization of complex mixtures of unknown initial composition, this presents a significant concern. Mixed-multimer formation could potentially lead to results that bare no resemblance to the original mixture. Conversely, ESI-MS has continually reflected subtle differences between natural organic matter mixtures that are in agreement with prediction or theory. Knowing the real limitations of the technique is therefore critical to avoiding both over-interpretation and unwarranted skepticism. Here, data were collected on four mass spectrometers under a battery of conditions. Results indicate that formation of unrepresentative ions cannot entirely be ruled out, but non-covalent multimers do not appear to make a major contribution to typical natural organic matter spectra based on collision-induced dissociation results. Multimers also appear notably reduced when a cooling gas is present in the accumulation region of the mass spectrometer. For less complex mixtures, the choice of spray solvent can make a difference, but generally spectrum cleanliness (i.e. representativeness) comes at the price of increased selectivity. PMID:24719347

Novotny, Nicole R; Capley, Erin N; Stenson, Alexandra C

2014-04-01

69

The viscosities and densities of selected organic compounds and mixtures of interest in coal liquefaction studies  

NASA Astrophysics Data System (ADS)

Experimental measurements are presented for the density and viscosity of selected organic compounds and mixtures at ambient pressure (0.083 MPa) and at temperatures of 298, 318, 338, and 358 K. The compounds studied were decalin, 1-methylnaphthalene, tetralin, m-xylene, tetrahydrofuran, thiophene, quinoline 2,6-lutidine, and m-cresol. Measurements were also made on three mixtures of the compounds decalin, 1-methylnaphthalene, tetralin, m-xylene, and m-cresol. The experimental results are compared with predictions made using a modified corresponding states procedure called TRAPP. The density predictions for the individual compounds and mixtures are good in all cases. For the viscosity, however, the predictions are in reasonable agreement with experiment only for nonassociating compounds and mixtures at reduced densities less than 3. These results suggest that TRAPP may prove very useful as a screening test to distinguish between nonassociating and highly associating mixtures. Such a test would be extremely useful when dealing with mixtures of unknown composition, such as coal liquids.

Oshmyansky, Y.; Hanley, H. J. M.; Ely, J. F.; Kidnay, A. J.

1986-05-01

70

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.

71

Laboratory measurements of the oxidation kinetics of organic aerosol mixtures using a relative rate constants approach  

NASA Astrophysics Data System (ADS)

Organic aerosols in the atmosphere are exposed to oxidants, but the oxidation kinetics are largely unknown. We investigate the decay of organic species in laboratory-generated organic aerosols exposed to atmospherically relevant ozone concentrations in a smog chamber. The experiments were conducted using five different organic aerosols, varying in complexity from three to twelve components. These mixtures include alkenoic acids, alkanoic acids, alkanedioic acids, n-alkanes, and sterols and are designed to simulate meat cooking emissions. A relative rate constants approach was used to compare reaction rates of individual organic species and to compare the reaction rates of the aerosol species to gas phase tracers. Significant decay was observed for all species (except for the n-alkanes) in at least one of the experimental systems. By relating the decomposition of condensed phase alkenoic acids to gas phase alkenes, we show that the reaction rate constants of oleic acid and palmitoleic acid evolve as the aerosol is processed, decreasing by a factor of ˜10 over the course of a 4-hour experiment. The decay rate constants of cholesterol, oleic acid, and palmitic acid all depend strongly on aerosol composition, with more than an order of magnitude change in the effective rate constants depending on mixture composition. Effects of aerosol composition are likely to be even more significant in atmospheric aerosol, where particle compositions are highly variable. The data presented here indicate these mixture effects are complicated, making it difficult to extrapolate from simple laboratory systems to atmospherically relevant conditions.

Huff Hartz, Kara E.; Weitkamp, Emily A.; Sage, Amy M.; Donahue, Neil M.; Robinson, Allen L.

2007-02-01

72

Evidence for liquid-like and nonideal behavior of a mixture of organic aerosol components  

PubMed Central

The condensation, evaporation, and repartitioning of semivolatile organic compounds (SVOCs) in the atmosphere depends both on the phase of condensed material and the effective condensed phase vapor pressures of the SVOCs. Although direct measurements of vapor pressures of individual SVOCs exist, there are limited measurements of how the properties of a given compound changes in mixtures of multiple components that exist in the atmosphere. Here, the evaporation behavior of mixtures of dicarboxylic acids, which are common atmospheric aerosol constituents, is investigated. These measurements demonstrate that complex mixtures of the individually solid organic compounds take on liquid-like properties. Additionally, the vapor pressures of individual components show strong, identity-dependent deviations from ideality (i.e., Raoult's Law), with the vapor pressures of the smaller, more volatile compounds decreased significantly in the mixtures. The addition of an inorganic compound (NaNO3) further influences the nonideal behavior, again in a compound-specific manner. These results suggest that nonideal behavior of particle-phase compounds influences the abundances of organic aerosol observed in the atmosphere and in the laboratory.

Cappa, Christopher D.; Lovejoy, Edward R.; Ravishankara, A. R.

2008-01-01

73

Prediction of two phase flow condensation of pure and refrigerant mixtures on enhanced surface tubing  

SciTech Connect

In this paper, the heat transfer characteristics of two phase flow condensation of pure refrigerants, as well as non-azeotropic refrigerant mixtures R-22/R-114 and R-22/R-152a, on horizontal enhances surface tubing is presented. Results showed that the enhancement of the heat transfer depends on the mixture components and their concentrations.

Sami, S.M.; Schnotale, J. (Mechanical Engineering School of Engineering, Univ. of Moncton, Moncton, New Brunswick E1A 3E9 (CA))

1992-03-01

74

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

75

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

76

Assessment of time to pregnancy and spontaneous abortion status following occupational exposure to organic solvents mixture  

Microsoft Academic Search

Purpose  Due to increasing usage of chemicals in various industries, occupational exposure of women with these materials is unavoidable.\\u000a Nowadays, some studies indicate adverse effects of exposure to these chemicals, especially organic solvents on the reproductive\\u000a system of females. This study aimed to assess the relationship between spontaneous abortion and occupational exposure to organic\\u000a solvents mixture in pharmaceutical industry.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  This study

Mir Saeed Attarchi; Monir Ashouri; Yasser Labbafinejad; Saber Mohammadi

77

POTENTIAL OF NON - AZEOTROPIC REFRIGERANT MIXTURE AS WORKING REFRIGERANT IN HOT WATER HEAT PUMPS  

Microsoft Academic Search

Industry is only using 20% of the heat subtracted from fossil fuels. The other 80% is released to the surroundings leading to an increase in the global warming effect. In contrast to this, the output of a heat pump is always more than the input, it delivers up to 67% energy savings, has less pollution than conventional heating methods and

FJ Smit

78

Experimental investigation of optimal conventional control strategy for a heterogeneous azeotropic distillation column  

Microsoft Academic Search

In this work, a laboratory scale sieve plate distillation column was constructed to investigate the optimum conventional control strategy of an isopropyl alcohol(IPA), cyclohexane(CyH) and water(H20) heterogeneous azeotropic distillation column. Steady state process analysis showed that the optimal operation point should be located at a critical reflux, a transition point at which the distillation path switches from a route that

R. F. Shih; W. T. Liu; C. S. Tsai; C.-H. Lee; S.-H. Cheng

1999-01-01

79

Implementation of Ethanol Dehydration Using Dividing-Wall Heterogeneous Azeotropic Distillation Column  

Microsoft Academic Search

In this article, the design and optimization procedures of a dividing-wall column for heterogeneous azeotropic distillation (DWC-A) using cyclohexane as an entrainer for ethanol dehydration are investigated. The proposed procedures can detect the optimal values of the design variables and thereby guarantee the minimum energy requirements, which is related to the minimum CO2 emissions and the lowest total annual cost

Lan-Yi Sun; Xing-Wu Chang; Cai-Xia Qi; Qing-Song Li

2011-01-01

80

Separation of benzene\\/cyclohexane mixtures by pervaporation using PEBA membranes  

Microsoft Academic Search

Separation of the benzene\\/cyclohexane mixture is industrially significant. The aim of the study is to disrupt the azeotropic behaviour of the benzene\\/cyclohexane mixtures by pervaporation using Pebax membranes. To overcome the difficulty of the separation benzene\\/cyclohexane mixtures by conventional techniques, pervaporation should be used. For this purpose, sorption and pervaporation of benzene\\/cyclohexane mixtures was studied by using different grades of

Ahmet E. Yildirim; Nilufer Durmaz Hilmioglu; Sema Tulbentci

2008-01-01

81

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

82

Formation of secondary organic aerosol from irradiated ?-pinene\\/toluene\\/NOx mixtures and the effect of isoprene and sulfur dioxide  

Microsoft Academic Search

Secondary organic aerosol (SOA) was generated by irradiating a series of ?-pinene\\/toluene\\/NOx mixtures in the absence and presence of isoprene or sulfur dioxide. The purpose of the experiment was to evaluate the extent to which chemical perturbations to this base-case (?-pinene\\/toluene) mixture led to changes in the gas-phase chemistry which strongly influences mass and composition of SOA and secondary organic

Mohammed Jaoui; Edward O. Edney; Tadeusz E. Kleindienst; Michael Lewandowski; John H. Offenberg; Jason D. Surratt; John H. Seinfeld

2008-01-01

83

Prediction of excess molar volumes of binary mixtures of organic compounds from refractive indices  

Microsoft Academic Search

The excess molar volumes of 51 binary mixtures containing diverse groups of organic compounds: alcohols (methanol, ethanol,\\u000a propan-1-ol, butan-1-ol, pentan-1-ol, hexan-1-ol, and heptan-1-ol), (cyclo-) alkanes (hexane, heptane, octane, nonane, decane,\\u000a undecane, dodecane, and cyclohexane), esters (diethyl carbonate and ethyl chloroacetate), aromatics (o-xylene, m-xylene, p-xylene, and ethylbenzene), ketones (acetone), and ethers (anisole), were predicted from the refractive index data, using\\u000a three

Ivona R. Radovi?; Mirjana Lj. Kijev?anin; Marijan Z. Gabrijel; Slobodan P. Šerbanovi?; Bojan D. Djordjevi?

2008-01-01

84

Rotational Diffusion of Organic Solutes in 1-Methyl-3-octylimidazolium Tetrafluoroborate-Diethylene Glycol Mixtures: Influence of Organic Solvent on the Organized Structure of the Ionic Liquid.  

PubMed

Rotational diffusion of two structurally similar organic solutes, 9-phenylanthracene (9-PA) and rhodamine 110 (R110), has been investigated in 1-methyl-3-octylimidazolium tetrafluoroborate-diethylene glycol ([MOIM][BF4]-DEG) mixtures to understand the influence of organic solvent on the organized structure of the ionic liquid. The reorientation times (?r) of nonpolar and charged solutes have been measured as a function of viscosity (?) by changing the temperature (T) as well as the composition of the ionic liquid-organic solvent mixture. These results when analyzed using the Stokes-Einstein-Debye (SED) hydrodynamic theory follow the relationship ?r = A(?/T)(n), where A is the ratio of hydrodynamic volume of the solute to Boltzmann constant. However, in neat [MOIM][BF4] and up to 0.4 mole fraction of DEG (xDEG), significant deviations from the SED hydrodynamic theory have been noticed with n being much less than unity. As xDEG is increased further, the parameters A and n increase considerably for both solutes, and their rotational diffusion follows the predictions of the SED hydrodynamic theory. It has also been observed that the trends in the variation of ?r with ?/T for 9-PA and R110 are not similar. These observations have been rationalized by taking into consideration the organized structure of the ionic liquid, which gradually becomes homogeneous at the microscopic level with the addition of the organic solvent. PMID:24802052

Prabhu, Sugosh R; Dutt, G B

2014-05-22

85

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

PubMed

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

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

2009-06-01

86

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

SciTech Connect

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

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

2009-06-15

87

Clinical neurological findings among car painters exposed to a mixture of organic solvents.  

PubMed

A full clinical neurological examination was used to study the possible effects of long-term exposure to low concentrations of mixtures of organic solvents on the nervous system. The exposed group consisted of 102 male car painters and the referents of 102 age- and sex-matched locomotive engineers and assistants. The psychoorganic syndrome, a decrease in the sense of light touch and pain, and an increase in the vibration threshold were more frequent among the car painters than among the referents, and the observed differences of these frequencies were statistically significant. The sense of vibration had been affected in the lower extremities of 65 of the 102 car painters and in 25 of the referents. Sensory functions seem to be the most vulnerable part of the nervous system of workers chronically exposed to different organic solvents. PMID:6247761

Husman, K; Karli, P

1980-03-01

88

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

89

Slow desorption mechanisms of volatile organic chemical mixtures in soil and sediment micropores.  

PubMed

Desorption profiles of trichloroethylene (TCE), tetrachloroethylene (PCE), and a TCE-PCE mixture were measured for three natural solids and four zeolites. Initial sorbed mass (Mi) in slow desorbing sites of natural solids and in micropores of zeolites were obtained from desorption profiles. In natural solids, Mi increases with recalcitrant organic matter content. In zeolites, Mi generally increases with decreasing micropore width and increasing micropore hydrophobicity, but the effect of hydrophobicity is stronger. In both natural solids and zeolites, competition between TCE and PCE causes Mi for each sorbate in the mixture to be less than or similar to that for each sorbate alone. Zeolite results indicate that micropore width affects this competition more than micropore hydrophobicity for the solids examined. Desorption in all solids was simulated with the radial diffusion model, either alone or coupled with the advection-dispersion equation when necessary; diffusion rate constants (D/R2) were obtained. In natural solids, mean values of D/R2 increase with decreasing recalcitrant organic matter content. In zeolites, values of D/R2 generally increase with increasing micropore width, while they are a weak function of hydrophobicity. In both natural solids and zeolites, competition between TCE and PCE causes D/R2 for each sorbate in the mixture to generally be larger than that for each sorbate alone. Zeolite results indicate that the effects of competition on D/R2 generally decrease with decreasing micropore width for the solids examined; a trend with micropore hydrophobicity is not apparent. For the three natural solids and four zeolites examined in this study, the similar effects of competition between TCE and PCE on values of Mi and D/R2 and the overlapping range of D/R2 values support the hypothesis that diffusion through hydrophobic micropores affects and may control slow mass transfer processes in the recalcitrant organic matter of natural solids. These results contribute to the fundamental understanding of slow mass transfer processes in natural solids, and they indicate that characterization of micropore width and polarity may be necessary to predict organic chemical transport and fate. PMID:14750718

Li, Jun; Werth, Charles J

2004-01-15

90

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

91

Secondary organic aerosol formation from xylenes and mixtures of toluene and xylenes in an atmospheric urban hydrocarbon mixture: Water and particle seed effects (II)  

NASA Astrophysics Data System (ADS)

Secondary organic aerosol (SOA) formation from the photooxidation of o-, p-xylene, and toluene with xylene mixtures was investigated in the UNC dual outdoor smog chambers. Experiments were performed with different initial background aerosol concentrations and levels of relative humidity (RH) in the environment of an eleven component mixture of non-SOA-forming dilute urban hydrocarbon mixture, oxides of nitrogen and sunlight. Post-nucleation was observed in most of the experiments in the 14-20 nm range except under the conditions with high background aerosol (>5 ?g m -3) and with low o-xylene concentrations (<0.092 ppmv). The SOA yields of o-xylene varied from 0.8% to 6.5% depending on the RH and initial seed concentrations. p-Xylene had a lower SOA yield compared with o-xylene and the yields in experiments with toluene and xylene mixtures ranged from 1.1% to 10.3%. SOA yield was found to be positively correlated with the particle water (H 2Op) content. A new condensed aromatic kinetic mechanism employing uptake of organics in H 2Op as a key parameter was applied to all the experiments and the simulations showed reasonable fits to the observed data.

Zhou, Yang; Zhang, Haofei; Parikh, Harshal M.; Chen, Eric H.; Rattanavaraha, Weruka; Rosen, Elias P.; Wang, Wenxing; Kamens, Richard M.

2011-07-01

92

Dielectric behavior of DNA in water-organic co-solvent mixtures.  

PubMed

The radiowave dielectric dispersions of DNA in different water-organic co-solvent mixtures have been measured in the frequency range from 100 kHz to 100 MHz, where the polarization mechanism is generally attributed to the confinement of counterions within some specific lengths, either along tangential or perpendicular to the polyion chain. The dielectric dispersions have been analyzed on the basis of two partially different dielectric models, a continuum counterion fluctuation model proposed by Mandel and a discrete charged site model, proposed by Minakata. The influence of the quality of the solvent on the dielectric parameters has been investigated in water-methanol and water-glycerol mixtures at different composition, by varying the permittivity (m) and the viscosity eta of the solvent phase. The analysis of the dielectric spectra in solvents where electrostatic and hydrodynamic interactions vary with the solvent composition suggests that both the two models are able, in principle, to account for the observed high-frequency dielectric behavior. However, while some certain assumptions are necessary about the polyion structure within the Mandel model, no structural prerequisite is needed within the Minakata model, where the polarization mechanism invoked considers a radial counterion exchange with the outer medium, which is largely independent of the local polyion conformation. PMID:16380204

Bonincontro, A; Cametti, C; Nardiello, B; Marchetti, S; Onori, G

2006-04-20

93

Molecular dynamics simulation studies on ethane and acetylene mixture in CuBTC metal organic framework  

NASA Astrophysics Data System (ADS)

Molecular Dynamics (MD) simulation studies have been carried out on the mixture containing ethane and acetylene molecules in 1:1 ratio at various concentrations of each species in CuBTC metal organic framework (MOF). MOFs are important class of materials which are tremendously useful for applications such as gas storage and separation. They have complex structure consisting of pore and pockets connected by windows. Results obtained from MD simulation showed that the self diffusivity of the ethane increases with the concentration while it decreases in case of acetylene. Correlation effects are responsible for this kind of phenomena. Pair distribution function showed the strong peaks at higher correlation length indicating the complex crystalline structure of the host matrix. We have also obtained the velocity auto correlation function (VACF) and velocity cross correlation functions (VCCF) at each studied concentration and found that the contribution from VCCF is almost negligible at lower concentration. Since the transport properties of mixture also depend on the mutual diffusivity and distinct diffusivity besides the self diffusivity, attempt has been made to quantify both the diffusivities. In the present system, at lower concentration, contribution to the mutual diffusivity comes from self diffusivities of species alone and distinct diffusivity contributes only at higher concentration.

Prabhudesai, S. A.; Sharma, V. K.; Mitra, S.; Mukhopadhyay, R.

2014-04-01

94

Freezing of binary hard-sphere mixtures into disordered crystals: a density functional approach  

Microsoft Academic Search

The density functional theory of freezing is extended to the crystallisation of multicomponent systems into substitutional solid solutions. The formalism is applied to the case of binary mixtures of hard spheres. As the ratio of diameters alpha = sigma 1\\/ sigma 2 is lowered, the fluid-solid phase diagram evolves from a spindle shape (1> alpha >0.94) into an azeotropic diagram

J. L. Barrat; M. Baus; J. P. Hansen

1987-01-01

95

Selection of ionic liquids for the extraction of aromatic hydrocarbons from aromatic\\/aliphatic mixtures  

Microsoft Academic Search

The separation of aromatic hydrocarbons (benzene, toluene, ethyl benzene and xylenes) from C4 to C10 aliphatic hydrocarbon mixtures is challenging since these hydrocarbons have boiling points in a close range and several combinations form azeotropes. In this work, we investigated the separation of toluene from heptane by extraction with ionic liquids.Several ionic liquids are suitable for extraction of toluene from

G. Wytze Meindersma; André B. de Haan

2005-01-01

96

Do stable nanobubbles exist in mixtures of organic solvents and water?  

PubMed

Several recent papers have described the existence of stable nanobubbles in bulk, which is surprising given that the high curvature of these bubbles is expected to place such bubbles under a high pressure and therefore lead to rapid dissolution. Here, we investigate the possible existence of nanobubbles in mixtures of water plus an organic solvent using both static and dynamic light scattering and infrared spectroscopy. The mixing of solvents was designed to introduce nanobubbles into bulk solution via supersaturation of the solution. The solutions scatter light for a long period (days) after mixing, which is consistent with the formation of nanoscale objects, but we show that these scattering objects originate from water-insoluble impurities in the organic solvents. Our results are inconsistent with the presence of gas nanobubbles in bulk solution: Degassing the solutions, either before or after mixing, has a minimal effect on the scattering, and purification of the organic solvent before mixing reduces the scattering after mixing. Therefore, previous reports of nanobubbles based on scattering experiments should be reconsidered with the hypothesis that the scattering objects are not actually gaseous. PMID:20438095

Häbich, Annette; Ducker, William; Dunstan, Dave E; Zhang, Xuehua

2010-05-27

97

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

SciTech Connect

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

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

1990-03-01

98

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

SciTech Connect

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

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

1990-11-01

99

Atmospheric pressure photoionization proton transfer for complex organic mixtures investigated by fourier transform ion cyclotron resonance mass spectrometry  

Microsoft Academic Search

To further clarify the role of dopant solvent in proton transfer in atmospheric pressure photoionization (APPI), we employ\\u000a ultrahigh-resolution FT-ICR mass analysis to identify M+•, [M+H]+, [M-H]?, and [M+D]+ species in toluene or perdeuterotoluene for an equimolar mixture of five pyrrolic and pyridinic nitrogen heterocyclic model\\u000a compounds, as well as for a complex organic mixture (Canadian Athabasca bitumen middle distillate).

Jeremiah M. Purcell; Christopher L. Hendrickson; Ryan P. Rodgers; Alan G. Marshall

2007-01-01

100

Rapid removal of selected volatile organic compounds from gaseous mixtures using a new dispersive vapor extraction technique: A feasibility study  

Microsoft Academic Search

A new dispersive vapor extraction (DVE) technique for rapid removal of selected volatile organic compounds (VOCs) from gaseous mixtures was investigated. In this technique, less than 1.0mL of a volatile solvent was vaporized for 8min in a 250-mL flask containing a gaseous mixture. The flask was then cooled under running tap water for 2–3min to induce condensation of the vapor

E. S. Farrell; G. E. Pacey

2010-01-01

101

Solubility, Sorption and Transport of Hydrophobic Organic Chemicals in Complex Mixtures. Environmental Research Brief.  

National Technical Information Service (NTIS)

Environmental contamination problems commonly involve Wastes consisting of complex mixtures of chemicals. The behavior of these mixtures has not been well understood because the primary chemodynamic properties (e.g. Solubility, sorption, transport) of org...

A. Lee A. L. Wood L. S. Rao

1991-01-01

102

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

Microsoft Academic Search

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

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

1999-01-01

103

IUPAC-NIST Solubility Data Series. 98. Solubility of Polycyclic Aromatic Hydrocarbons in Pure and Organic Solvent Mixtures: Revised and Updated. Part 2. Ternary Solvent Mixtures  

NASA Astrophysics Data System (ADS)

This work updates Vols. 54, 58, and 59 in the IUPAC Solubility Data Series and presents solubility data for polycyclic aromatic hydrocarbon solutes dissolved in ternary organic solvent mixtures. Published solubility data for anthracene, phenanthrene, and pyrene that appeared in the primary literature between 1995 to the end of 2011 are compiled and critically evaluated. Experimental solubility data for 119 different solute-ternary solvent systems are included in the volume. Solubility data published prior to 1995 were contained in three earlier volumes (Vols. 54, 58, and 59) and are not repeated here.

Acree, William E.

2013-03-01

104

IUPAC-NIST Solubility Data Series. 98. Solubility of Polycyclic Aromatic Hydrocarbons in Pure and Organic Solvent Mixtures: Revised and Updated. Part 1. Binary Solvent Mixtures  

NASA Astrophysics Data System (ADS)

This work updates Vols. 54, 58, and 59 in the IUPAC Solubility Data Series and presents solubility data for polycyclic aromatic hydrocarbon solutes dissolved in binary organic solvent mixtures. Published solubility data for anthracene, naphthalene, phenanthrene, phenothiazine, and pyrene that appeared in the primary literature between 1995 to the end of 2011 are compiled and critically evaluated. Experimental solubility data for 360 different solute-binary solvent systems are included in the volume. Solubility data published prior to 1995 were contained in three earlier volumes (Vols. 54, 58, and 59) and are not repeated in this volume.

Acree, William E.

2013-03-01

105

SOA formation in a photoreactor from a mixture of organic gases and HONO for different experimental conditions  

Microsoft Academic Search

Smog chambers have been extensively used to investigate the chemical routes of oxidation reactions for several organic gases. In this study we present the results of a set of experiments performed in the EUPHORE photoreactor to analyze SOA formation from a mixture of four organic gases related to anthropogenic emissions (1,3,5-trimethylbenzene, o-xylene, octane and toluene) with an oxidant under different

Marta G. Vivanco; Manuel Santiago; Adela Martínez-Tarifa; Esther Borrás; Milagros Ródenas; Cristina García-Diego; Miguel Sánchez

2011-01-01

106

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...

107

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...

108

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

109

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

NASA Astrophysics Data System (ADS)

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

Chen, Tianyi; Jang, Myoseon

2012-01-01

110

Human reactions to a mixture of indoor air volatile organic compounds  

NASA Astrophysics Data System (ADS)

A controlled experimental study of human reactions to a mixture of 22 volatile organic compounds often found in indoor air was performed in a climate chamber. Twenty-one healthy subjects were compared with a group of 14 subjects suffering from the 'sick building syndrome' (SBS subjects), i.e. having symptoms related to the indoor environment (irritated mucous membranes, headache, etc.) as defined by WHO in 1982. In groups of 4 these subjects were exposed during two successive periods to either 0 and 0 mg m -3, 25 and 0 mg m -3, or 0 and 25 mg m -3; 25 mg m -3 is equivalent to the highest concentrations expected in a new building. The study was double blinded, and a latin square design was used to balance out effects of day in the week and season. Both groups reacted subjectively to the air reporting worse odor, worse indoor air quality as defined by the subject, and more irritated mucous membranes in eye, throat and nose than in the clean environment. A tendency to a stronger response was seen among the SBS subjects. Objective measures indicated among others an exposure related reduction in lung function among SBS subjects. Both groups had an increased number of polymorphonuclear leucocytes in tear fluid as a result of exposure. This was not seen for nasal secretions. Psychological performance tests indicated an exposure related diminished ability to learn. In conclusion, the experiment indicates that exposure to volatile organic compounds in low concentrations as seen in new houses causes both subjective complaints and objective signs in normal healty subjects; but more so in subjects from the sick building syndrome.

Kjærgaard, Søren K.; Mølhave, Lars; Pedersen, Ole F.

111

Respirometric evaluation of a mixture of organic chemicals with different biodegradation kinetics.  

PubMed

The study evaluated the biodegradation characteristics of a mixture of organics with different biodegradation characteristics in an integrated chemical plant effluent. The wastewater had a total chemical oxygen demand (COD) content of 12,800mg/L, mostly soluble and 93% biodegradable. The evaluation was based on respirometry, and mainly consisted on model calibration and interpretation of the oxygen uptake rate data, which exhibited an original and specific profile with a sequence of two peaks and three plateaus. A specific model was defined for this purpose, which identified four different biodegradable COD components with significantly different process kinetics. The major fraction accounting for 57% of the total biodegradable COD in the wastewater had to be hydrolyzed before biodegradation with a low hydrolysis rate of 1.3day(-1). The analysis of the experimental data showed that the oxygen utilization started with a delayed response after substrate addition. The delayed logarithmic phase could be characterized by a Haldane type of inhibition kinetics. PMID:18439757

Cokgor, Emine Ubay; Insel, Güçlü; Aydin, Egemen; Orhon, Derin

2009-01-15

112

Secondary organic aerosol formation from toluene in an atmospheric hydrocarbon mixture: Water and particle seed effects  

NASA Astrophysics Data System (ADS)

Atmospherically relevant secondary organic aerosol (SOA) concentrations from toluene, in an urban hydrocarbon environment, with oxides of nitrogen in natural sunlight, were studied in a large outdoor chamber with different initial humidity and types of initial seed aerosols. Ammonium sulfate particles (38 ?g m -3) in the presence of an atmospheric hydrocarbon mixture and NOx in sunlight under a dry atmosphere (%RH = 6 to 10%) show reduced SOA formation when compared to similar gas phase conditions with lower ammonium sulfate (7 ?g m -3) and higher relative humidities (%RH 40 to 90%). No post particle nucleation (particles in the 6 to 10 nm range) was observed in either seeded system. When initial background particles levels were below 0.5 ?g m -3 particle nucleation was observed. A new condensed aromatic kinetic chemical mechanism was developed to simulate experimental data. A particle water phase was highly related to SOA formation. Reasonable fits to the gas and total SOA concentrations emphasize the important impact of different initial particle seed levels and particle phase water when simulating SOA formation from aromatic compounds like toluene.

Kamens, Richard M.; Zhang, Haofei; Chen, Eric H.; Zhou, Yang; Parikh, Harshal M.; Wilson, Rebecca L.; Galloway, Katherine E.; Rosen, Elias P.

2011-04-01

113

Exposure of humans to a volatile organic mixture. 3. Inflammatory response  

SciTech Connect

A set of symptoms has been described during the past two decades that has been called the sick building syndrome. These symptoms include eye, nose, and throat irritation; headache; mental fatigue; and respiratory distress. It is likely that the volatile organic compounds (VOCs) present in synthetic materials used in homes and office buildings contribute to these symptoms. However, there have been very few studies in which humans have been exposed to known amounts of VOCs under carefully controlled conditions. In the study, 14 subjects were exposed to a mixture of VOCs (25 mg/sq meter total hydrocarbon) that is representative of what is found in new homes and office buildings. Because irritations of the nose and throat are symptoms often associated with the upper respiratory tract and may result from an inflammatory response in the upper airways, the authors used nasal lavage to monitor neutrophil (PMN) influx into the nasal passages following exposure to VOCs. There were statistically significant increases in PMNs, both immediately after a 4-h exposure to VOCs and 18 h later.

Koren, H.S.; Graham, D.E.; Devlin, R.B.

1992-01-01

114

Phase Transitions and Spatial Organization in Nanoparticle-Block Copolymer Mixtures  

NASA Astrophysics Data System (ADS)

Introducing nanoparticles into nanostructured block copolymer phases can dramatically influence the polymer host. Computer simulations [Balazs et al., PRL, 89, 155503 (2002)] suggest inclusions can actually trigger transitions from one polymer phase to another. Simultaneously, the nanoparticles can be organized into complex superstructures, giving composite materials with novel mechanical, electrical and optical properties. Potential applications include catalysts, selective membranes and optical filters. We have developed a first principles theory predicting polymer phases and nanoparticle distributions. We find modification by nanoinclusions of the free energy of stretched polymer domains in lamellar, cylindrical or spherical geometries triggers structural changes and determines particle distributions. Our framework builds on Semenov's description of AB copolymers in the strongly stretched limit by incorporating nanoinclusions. Energy favors segregation into particle-rich regions, while entropy favors particle mixing into the energetically preferred block, say A. When entropy wins (small particles), an A-core cylindrical-to-lamellar phase transition is induced. Interestingly, large particles by contrast microphase separate into copolymer domains (analogous to Semenov's conclusions for homopolymer-copolymer mixtures) triggering reverse phase transitions (e.g. lamellar to A-core cylindrical). We present our results as a complete phase diagram.

Kim, Jaeup

2005-03-01

115

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

116

Fundamental measure density functional theory studies on the freezing of binary hard-sphere and Lennard-Jones mixtures  

SciTech Connect

Free energies and correlation functions of liquid and solid hard-sphere (HS) mixtures are calculated using the fundamental measure density functional theory. Using the thermodynamic perturbation theory the free energies of solid and liquid Lennard-Jones (LJ) mixtures are obtained from correlation functions of HS systems within a single theoretical approach. The resulting azeotrope- and spindle-type solid-liquid phase diagrams of HS and LJ binary mixtures are in good agreement with the corresponding ones from computer simulations.

Warshavsky, Vadim B.; Song, Xueyu

2008-07-18

117

A Heat Pump Operating with a Mixture of Fluids (Pompe a Chaleur Fonctionnant avec un Melange de Fluides).  

National Technical Information Service (NTIS)

The coefficient of performance of a heat pump system comprising an external heat exchange medium may be increased if a non-azeotropic mixture of hydrocarbons or Freons as working fluid is used so that it vaporizes or condenses with a change in temperature...

A. Rojey C. Meyer B. Choffe J. Jacq L. Asselineau

1980-01-01

118

Characteristics of adsorption phase with water/organic mixtures at a surface of activated carbons possessing intraparticle and textural porosities  

NASA Astrophysics Data System (ADS)

The behaviour of water and water/organic mixtures adsorbed onto activated microporous carbons or a carbon adsorbent with narrow intraparticle micropores and broad mesopores and macropores between nanoparticles was studied using low-temperature adsorption method and 1H NMR spectroscopy with layer-by-layer freezing-out of liquids at 190-273 K. These investigations revealed concentration-dependent effects of benzene, DMSO, acetone, chloroform, methane and acetonitrile on the characteristics of adsorbed water and the influence of this water on the interfacial behaviour of adsorbed organics. The influence of organics causes the structural and energetic differentiations of adsorbed water. The latter can be displaced by organics from micropores into broader pores and/or form mixture with polar solvents in meso and macropores. Freezing of adsorbed water can affect the adsorbent structure because ice crystallites have a larger size than that of liquid water droplets that lead to changes in the behaviour of adsorbed water/organic mixtures observed by the 1H NMR and adsorption methods.

Gun'ko, V. M.; Turov, V. V.; Kozynchenko, O. P.; Palijczuk, D.; Szmigielski, R.; Kerus, S. V.; Borysenko, M. V.; Pakhlov, E. M.; Gorbik, P. P.

2008-03-01

119

Isobaric Vapor-Liquid Equilibrium Data for Binary Mixture of 2-Methyltetrahydrofuran and  

Microsoft Academic Search

Isobaric vapor-liquid equilibrium measurements are reported for binary mixture of 2-Methyltetrahydrofuran and Cumene at 97.3 kPa. The data were obtained using a vapor recirculating type (modified Othmer's) equilibrium still. The mixture shows slight negative deviation from ideality. The system does not form an azeotrope. The experimental data obtained in this study are thermodynamically consistent according to the Herington test. The

V. K. Rattan; Baljinder K. Gill; Seema Kapoor

2008-01-01

120

Heat transfer and pressure drop characteristics of HFC quaternary refrigerant mixtures inside horizontal enhanced surface tubing  

Microsoft Academic Search

Heat transfer characteristics of two-phase flow condensation and boiling of quaternary (four components) refrigerant mixtures, on air\\/refrigerant horizontal enhanced surface tubing are presented, discussed and compared to other refrigerants proposed as substitutes for CFC-502, such as R-507 and R-407B. Heat transfer characteristics, such as average heat transfer coefficients, as well as pressure drops of ternary azeotropic refrigerant mixtures, flow condensation

S. M. Sami; B. Song

1996-01-01

121

Design and Synthesis Procedure for Homogeneous and Heterogeneous Azeotropic Distillations: Annual Report for Period March 1, 1986 to February 29, 1987.  

National Technical Information Service (NTIS)

The column sequencing problem for heterogeneous azeotropic distillation is investigated. It is shown that residue curve maps play an important role in interpreting the behavior of these systems. Classes of residue curve maps which give rise to feasible co...

M. F. Doherty

1986-01-01

122

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

123

Structural features of polymer adsorbent LiChrolut EN and interfacial behavior of water and water/organic mixtures.  

PubMed

The structural and adsorption characteristics of polymer adsorbent LiChrolut EN and the behavior of adsorbed water and water/organic mixtures were studied using adsorption, microcalorimetry, transmission and scanning electron microscopy, mass spectrometry, infrared spectroscopy, 1H NMR spectroscopy with layer-by-layer freezing-out of liquids (190-273 K), and thermally stimulated depolarization current method (90-265 K). This adsorbent is characterized by large specific surface area (approximately 1500 m2/g) and pore volume (0.83 cm3/g) with a major contribution of narrow pores (R<10 nm) of a complicated shape (long hysteresis loop is in nitrogen adsorption-desorption isotherm). The adsorbent includes aromatic and aliphatic structures and oxygen-containing functionalities and can effectively adsorb organics and water/organic mixtures. On co-adsorption of water and organics (dimethyl sulfoxide, chloroform, methane), there is a weak influence of one on another adsorbate due to their poor mixing in pores. Weakly polar chloroform displaces a fraction of water from narrow pores. These effects can explain high efficiency of the adsorbent in solid-phase extraction of organics from aqueous solutions. The influence of structural features of several carbon and polymer adsorbents on adsorbed nitrogen, water and water/organics is compared on the basis of the adsorption and 1H NMR data. PMID:18440015

Gun'ko, V M; Turov, V V; Zarko, V I; Nychiporuk, Y M; Goncharuk, E V; Pakhlov, E M; Yurchenko, G R; Kulik, T V; Palyanytsya, B B; Borodavka, T V; Krupskaya, T V; Leboda, R; Skubiszewska-Zieba, J; Osovskii, V D; Ptushinskii, Y G; Turov, A V

2008-07-01

124

Phase behaviour of deionized binary mixtures of charged colloidal spheres  

NASA Astrophysics Data System (ADS)

We review recent work on the phase behaviour of binary charged sphere mixtures as a function of particle concentration and composition. Both size ratios ? and charge ratios ? are varied over a wide range. Unlike the case for hard spheres, the long-ranged Coulomb interaction stabilizes the crystal phase at low particle concentrations and shifts the occurrence of amorphous solids to particle concentrations considerably larger than the freezing concentration. Depending on ? and ?, we observe upper azeotrope, spindle, lower azeotrope and eutectic types of phase diagrams, all known well from metal systems. Most solids are of body centred cubic structure. Occasionally stoichiometric compounds are formed at large particle concentrations. For very low ?, entropic effects dominate and induce a fluid-fluid phase separation. Since for charged spheres the charge ratio ? is also decisive for the type of phase diagram, future experiments with charge variable silica spheres are suggested.

Lorenz, Nina J.; Schöpe, Hans Joachim; Reiber, Holger; Palberg, Thomas; Wette, Patrick; Klassen, Ina; Holland-Moritz, Dirk; Herlach, Dieter; Okubo, Tsuneo

2009-11-01

125

Phase behaviour of deionized binary mixtures of charged colloidal spheres.  

PubMed

We review recent work on the phase behaviour of binary charged sphere mixtures as a function of particle concentration and composition. Both size ratios ? and charge ratios ? are varied over a wide range. Unlike the case for hard spheres, the long-ranged Coulomb interaction stabilizes the crystal phase at low particle concentrations and shifts the occurrence of amorphous solids to particle concentrations considerably larger than the freezing concentration. Depending on ? and ?, we observe upper azeotrope, spindle, lower azeotrope and eutectic types of phase diagrams, all known well from metal systems. Most solids are of body centred cubic structure. Occasionally stoichiometric compounds are formed at large particle concentrations. For very low ?, entropic effects dominate and induce a fluid-fluid phase separation. Since for charged spheres the charge ratio ? is also decisive for the type of phase diagram, future experiments with charge variable silica spheres are suggested. PMID:21715880

Lorenz, Nina J; Schöpe, Hans Joachim; Reiber, Holger; Palberg, Thomas; Wette, Patrick; Klassen, Ina; Holland-Moritz, Dirk; Herlach, Dieter; Okubo, Tsuneo

2009-11-18

126

Competitive anion transport in desalting of mixtures of organic acids by batch electrodialysis.  

SciTech Connect

Desalting and separation of binary and quaternary acid mixtures via batch electrodialysis are investigated in this article. A monoselective cation exchange membrane and either a non-selective or a monoselective anion exchange membrane are employed in the electrodialysis stack. The effects of current density and composition of the initial feed of the electrodialysis stack (employing a non-selective anion exchange membrane) on its performance are studied in experiments involving mixtures of acetic and succinic acids. The effect of the type of the anion exchange membrane on the process performance is examined in desalting experiments involving a mixture of acetic, formic, lactic, and succinic acids. The trends observed in the experiments are interpreted in terms of species-specific parameters (such as molar concentration, charge on ionic species, molecular weight, degree of ionization, and ionic equivalent conductivity) and characteristics of anion exchange membrane used.

Moon, P. J.; Parulekar, S. J.; Tsai, S.-P.; Energy Systems; Illinois Inst. of Tech.

1998-04-01

127

Iodometric microdetermination of organic oxidants and ozone: resolution of mixtures by kinetic colorimetry  

Microsoft Academic Search

A basic technique of kinetic colorimetry was developed for determining oxidants in mixtures. An appropriate reagent to produce a slowly developed color was added. Components were resolved graphically using a plot of logarithm of undeveloped color (maximum absorbance minus that at given time) vs. reaction time. Iodometric microdeterminations were thus made of liquid dilutions of various oxidants. This technique was

B. E. Saltzman; Nathan Gilbert

1959-01-01

128

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 ...

129

Complex mixture analysis of organic compounds in green coffee bean extract by two-dimensional NMR spectroscopy.  

PubMed

A complex mixture analysis by one- and two-dimensional nuclear magnetic resonance (NMR) spectroscopy was carried out for the first time for the identification and quantification of organic compounds in green coffee bean extract (GCBE). A combination of (1)H-(1)H DQF-COSY, (1)H-(13)C HSQC, and (1)H-(13)C CT-HMBC two-dimensional sequences was used, and 16 compounds were identified. In particular, three isomers of caffeoylquinic acid were identified in the complex mixture without any separation. In addition, GCBE components were quantified by the integration of carbon signals by use of a relaxation reagent and an inverse-gated decoupling method without a nuclear Overhauser effect. This NMR methodology provides detailed information about the kinds and amounts of GCBE components, and in our study, the chemical makeup of GCBE was clarified by the NMR results. PMID:20818806

Wei, Feifei; Furihata, Kazuo; Hu, Fangyu; Miyakawa, Takuya; Tanokura, Masaru

2010-11-01

130

Isobaric Vapor-Liquid Equilibrium of Binary Mixture of Methyl Acetate with Isopropylbenzene at 97.3 kPa  

Microsoft Academic Search

Isobaric vapor-liquid equilibrium measurements are reported for the binary mixture of Methyl acetate and Isopropylbenzene at 97.3 kPa. The measurements have been performed using a vapor recirculating type (modified Othmer's) equilibrium still. The mixture shows positive deviation from ideality and does not form an azeotrope. The activity coefficients have been calculated taking into consideration the vapor phase nonideality. The data

Seema Kapoor; Baljinder K. Gill; V. K. Rattan

2008-01-01

131

Flow boiling heat transfer coefficients at cryogenic temperatures for multi-component refrigerant mixtures of nitrogen-hydrocarbons  

NASA Astrophysics Data System (ADS)

The recuperative heat exchanger governs the overall performance of the mixed refrigerant Joule-Thomson cryocooler. In these heat exchangers, the non-azeotropic refrigerant mixture of nitrogen-hydrocarbons undergoes boiling and condensation simultaneously at cryogenic temperature. Hence, the design of such heat exchanger is crucial. However, due to lack of empirical correlations to predict two-phase heat transfer coefficients of multi-component mixtures at low temperature, the design of such heat exchanger is difficult.

Ardhapurkar, P. M.; Sridharan, Arunkumar; Atrey, M. D.

2014-01-01

132

Carcinogenesis, metabolism and DNA-binding studies of complex organic mixtures  

Microsoft Academic Search

Studies were conducted to determine the skin-tumor-initiating activity of complex mixtures of synfuel derivation. Data from previous studies indicated that solvent refined coal (SRC)-II heavy distillate (HD; boiling range, 550 to > 850°F) produced skin tumors in mice and that most of the carcinogenic activity occurred in materials boiling above 750°F. Two of the highest-boiling fractions (i.e., 800 to 850°F

D. L. Springer; D. D. Mahlum; R. B. Westerberg; K. L. Hopkins; M. E. Frazier; D. W. Later; W. C. Weimer

1984-01-01

133

PROCEDURES FOR DERIVING EQUILIBRIUM PARTITIONING SEDIMENT BENCHMARKS (ESBS) FOR THE PROTECTION OF BENTHIC ORGANISMS: METALS MIXTURES (CADMIUM, COPPER, LEAD, NICKEL, SILVER, AND ZINC)  

EPA Science Inventory

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

134

Titan in a Fume Hood: Room-Temperature Simulation of a Titan Evaporite Playa Using a Multi-Component Mixture of Organic Compounds  

NASA Astrophysics Data System (ADS)

A multi-component mixture of organic compounds in heptanes was evaporated to simulate the formation of an evaporite playa on Titan. The deposition sequence of the analog materials and their implications for Titan geology will be presented.

Malaska, M.; Radebaugh, J.; Barnes, J.; Mitchell, K.

2012-03-01

135

Laboratory investigation of thermal degradation of a mixture of hazardous organic compounds. 1  

SciTech Connect

In this report, the effect of oxygen concentration on the thermal stability of the components of a mixture of carbon tetrachloride, monochlorobenzene, 1,1,2-trichloro-,1,2,2-trifluoroethane (Freon 113 (Du Pont)), trichloroethylene, and toluene and the formation of thermal reaction products is examined. Thermal decomposition studies were conducted in atmospheres in which combustion oxygen was in excess, stoichiometric, and absent (pyrolysis). The components were also run individually in atmospheres with stoichiometric and excess oxygen. Results indicate that decreasing oxygen concentration increased the stability of the mixture components except Freon 113 and carbon tetrachloride. Furthermore, with the exception of Freon 113, each component was less stable in the mixture as compared to pure compound data. The stability of Freon 113 remained unchanged regardless of reaction atmosphere. It was found that the number and complexity of thermal reaction products increased with decreasing oxygen concentration. In all cases, products ranged from simple chlorinated aliphatics to complex polynuclear aromatics. 18 references, 7 figures, 2 tables.

Graham, J.L.; Hall, D.L.; Dellinger, B.

1986-07-01

136

Parameterization of thermal properties of aging secondary organic aerosol produced by photo-oxidation of selected terpene mixtures.  

PubMed

Formation and evolution of secondary organic aerosols (SOA) from biogenic VOCs influences the Earth's radiative balance. We have examined the photo-oxidation and aging of boreal terpene mixtures in the SAPHIR simulation chamber. Changes in thermal properties and chemical composition, deduced from mass spectrometric measurements, were providing information on the aging of biogenic SOA produced under ambient solar conditions. Effects of precursor mixture, concentration, and photochemical oxidation levels (OH exposure) were evaluated. OH exposure was found to be the major driver in the long term photochemical transformations, i.e., reaction times of several hours up to days, of SOA and its thermal properties, whereas the initial concentrations and terpenoid mixtures had only minor influence. The volatility distributions were parametrized using a sigmoidal function to determine TVFR0.5 (the temperature yielding a 50% particle volume fraction remaining) and the steepness of the volatility distribution. TVFR0.5 increased by 0.3 ± 0.1% (ca. 1 K), while the steepness increased by 0.9 ± 0.3% per hour of 1 × 10(6) cm(-3) OH exposure. Thus, aging reduces volatility and increases homogeneity of the vapor pressure distribution, presumably because highly volatile fractions become increasingly susceptible to gas phase oxidation, while less volatile fractions are less reactive with gas phase OH. PMID:24810838

Emanuelsson, Eva U; Mentel, Thomas F; Watne, Agot K; Spindler, Christian; Bohn, Birger; Brauers, Theo; Dorn, Hans-Peter; Hallquist, Asa M; Häseler, Rolf; Kiendler-Scharr, Astrid; Müller, Klaus-Peter; Pleijel, Håkan; Rohrer, Franz; Rubach, Florian; Schlosser, Eric; Tillmann, Ralf; Hallquist, Mattias

2014-06-01

137

Atmospheric pressure photoionization proton transfer for complex organic mixtures investigated by fourier transform ion cyclotron resonance mass spectrometry.  

PubMed

To further clarify the role of dopant solvent in proton transfer in atmospheric pressure photoionization (APPI), we employ ultrahigh-resolution FT-ICR mass analysis to identify M(+*), [M + H](+), [M - H](-), and [M + D](+) species in toluene or perdeuterotoluene for an equimolar mixture of five pyrrolic and pyridinic nitrogen heterocyclic model compounds, as well as for a complex organic mixture (Canadian Athabasca bitumen middle distillate). In the petroleum sample, the protons in the [M + H](+) species originate primarily from other components of the mixture itself, rather than from the toluene dopant. In contrast to electrospray ionization, in which basic (e.g., pyridinic) species protonate to form [M + H](+) positive ions and acidic (e.g., pyrrolic) species deprotonate to form [M - H](-) negative ions, APPI generates ions from both basic and acidic species in a single positive-ion mass spectrum. Ultrahigh-resolution mass analysis (in this work, m/Deltam(50%) = 500,000, in which Deltam(50%) is the mass spectral peak full width at half-maximum peak height) is needed to distinguish various close mass doublets: (13)C versus (12)CH (4.5 mDa), (13)CH versus (12)CD (2.9 mDa), and H(2) versus D (1.5 mDa). PMID:17689097

Purcell, Jeremiah M; Hendrickson, Christopher L; Rodgers, Ryan P; Marshall, Alan G

2007-09-01

138

EVALUATION OF THE NEPHROTOXICITY OF COMPLEX MIXTURES CONTAINING ORGANICS AND METALS: ADVANTAGES AND DISADVANTAGES OF THE USE OF REAL-WORLD COMPLEX MIXTURES  

EPA Science Inventory

The nephrotoxicity of complex industrial waste mixtures and a chemically-characterized synthetic chemical mixture are described and reviewed, respectively. dult, male F-344 rats were gavaged with samples of complex industrial waste and nephrotoxicity evaluated 24 hr later. of the...

139

Prediction of Molecular Separation of Polar-Apolar Mixtures on Heterogeneous Metal-Organic Frameworks: HKUST-1.  

PubMed

Due to the combination of metal ions and organic linkers and the presence of different types of cages and channels, metal-organic frameworks often possess a large structural and chemical heterogeneity, complicating their adsorption behavior, especially for polar-apolar adsorbate mixtures. By allocating isotherms to individual subunits in the structure, the ideal adsorbed solution theory (IAST) can be adjusted to cope with this heterogeneity. The binary adsorption of methanol and n-hexane on HKUST-1 is analyzed using this segregated IAST (SIAST) approach and offers a significant improvement over the standard IAST model predictions. It identifies the various HKUST-1 cages to have a pronounced polar or apolar adsorptive behavior. PMID:24914819

Van Assche, Tom R C; Duerinck, Tim; Van der Perre, Stijn; Baron, Gino V; Denayer, Joeri F M

2014-07-01

140

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

PubMed

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

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

2013-05-01

141

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.

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

2012-01-01

142

Laboratory Formation of Carbonaceous Particles in Dilute Gas Mixtures of Organic Molecules  

Microsoft Academic Search

Particles of various organic compositions have been observed in the atmospheres of the outer planets, their satellites, and comets. Infrared (IR) spectral features reveal the presence of these particles in the outer planetary system, especially Titan. ``CHON\\

R. J. Cody

1998-01-01

143

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-...

144

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

EPA Science Inventory

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

145

Solubilities of families of heterocyclic polynuclear aromatics in organic solvents and their mixtures  

SciTech Connect

The solubilities of anthracene, acridine, xanthene, thioxanthene, carbazole, dibenzofuran, and dibenzothiophene have been experimentally determined in benzene, cyclohexane, thiophene, and pyridine from ambient temperature to approximately 440 K. The results have been correlated using the classical equation for solid-liquid solubility to obtain the experimental activity coefficient of the solute in the solvent. These experimental activity coefficients have been regressed, using three common solution models, to find the binary interaction parameters needed in those models. The solubilities of biphenyl, dibenzofuran, and dibenzothiophene have been experimentally determined in five binary mixtures of the solvents. The experimental activity coefficients have been found and compared to the values predicted by the four solution models, using the binary interaction parameters obtained from the solubilities in the pure solvents and solvent-solvent binary interaction parameters obtained from literature vapor-liquid equilibria data. The effect of substituting various heteroatoms into the ring structure has been discussed.

Coon, J.E.; Sediawan, W.B.; Auwaerter, J.E.; McLaughlin, E.

1988-06-01

146

Slow Relaxation Mode in Mixtures of Water and Organic Molecules:  Supramolecular Structures or Nanobubbles?  

Microsoft Academic Search

Aqueous solutions of tetrahydrofuran, ethanol, urea, and R-cyclodextrin were studied by a combination of static and dynamic laser light scattering (LLS). In textbooks, these small organic molecules are soluble in water so that there should be no observable large structures or density fluctuation in either static or dynamic LLS. However, a slow mode has been consistently observed in these aqueous

Fan Jin; Jing Ye; Liangzhi Hong; Hiufung Lam; Chi Wu

2007-01-01

147

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

148

Pervaporative Removal of Organics from Water Using Hydrophobic Membranes. Binary Mixtures  

Microsoft Academic Search

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

WOJCIECH KUJAWSKI

2000-01-01

149

Experimental study of the heat transfer characteristics of refrigerant mixture R-22/R-114 in the annulus of enhanced surface tubing  

SciTech Connect

In this paper an experimental study of heat transfer characteristics of refrigerant mixture R-22/R-114 in the annuli of a horizontal enhanced surface tubing evaporator is presented. The enhanced surface tubing data showed a significant enhancement of the heat transfer compared to an equivalent smooth tube depending on the mixture's components and their concentrations. Correlations were proposed to predict the average heat transfer coefficients of R-22/R114 non-azeotropic refrigerant moisture flow boiling inside enhanced surface tubing.

Sami, S.M.; Duong, T.N. (Mechanical Engineering, School of Engineering, Univ. of Moncton, Moncton, New Brunswick E1A 3E9 (CA))

1991-07-01

150

Secondary Organic Aerosol Formation in Aerosol Water by Photochemical Reactions of Gaseous Mixture of Monoterpene and Hydrogen Peroxide  

NASA Astrophysics Data System (ADS)

There exist large uncertainties in model predictions for climate change and regional air quality. It could be caused by incomplete integration of secondary organic aerosol (SOA) formation in atmospheric chemical models. Recent laboratory studies have found SOA formation through chemical reactions on aerosol surface and in aerosol water. Water soluble organics formed by photochemical degradation of biogenic organics including isoprene and anthropogenic aromatics are predicted to form substantial amount of SOA through the newly found pathways. Although SOA formation in bulk aqueous solution was reported for laboratory experiments of various precursors (e.g., water soluble carbonyls and phenols), little is known for SOA formation in real aerosol water. In this study, photochemical reactions of the gaseous mixture of monoterpene and hydrogen peroxide were examined to investigate SOA formation through reactions in real aerosol phase water. SOA formation was conducted using a flow tube reactor (ID 30 cm x L 150 cm, FEP) and a smog chamber using FEP film in the presence of dry and wet seed particles. Acidity and chemical composition of seed aerosol were also controlled as important parameters influencing SOA formation. Particle size distribution and aerosol composition were analyzed to account for differences in SOA formation mechanisms and yields for dry and wet particles. The differences might be mainly associated with SOA formation in aerosol phase water. This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (No. 2011-0000221).

Lim, H.; Yi, S.; Park, J.; Cho, H.; Jung, K.

2011-12-01

151

Molecular dynamics investigation of the self-diffusion of binary mixture diffusion in the metal-organic framework Zn(tbip) accounting for framework flexibility  

Microsoft Academic Search

The self-diffusion of three equimolar mixtures in the metal-organic framework Zn(tbip) has been investigated by molecular dynamics simulations. The simulations take due account of lattice flexibility. The diffusional characteristics are discussed in relation to molecule properties and lattice geometry. The results show that Zn(tbip) may be a useful material for separating methane\\/ethane and CO2\\/ethane mixtures at low concentrations, and CO2\\/methanol

K. Seehamart; C. Chmelik; R. Krishna; S. Fritzsche

2011-01-01

152

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

153

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

SciTech Connect

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

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

1990-10-01

154

Coarsening and self-organization in dilute diblock copolymer melts and mixtures  

NASA Astrophysics Data System (ADS)

This paper explores the evolution of a sharp interface model for phase separation of copolymers in the limit of low volume fraction. Particles both exchange material as in usual Ostwald ripening, and migrate because of an effectively repulsive nonlocal energetic term. Coarsening via mass diffusion only occurs while particle radii are small, and they eventually approach a finite equilibrium size. Migration, on the other hand, is responsible for producing self-organized patterns. We construct approximations based upon an ansatz of spherical particles similar to the classical LSW theory to derive finite dimensional dynamics for particle positions and radii. For large systems, kinetic-type equations which describe the evolution of a probability density are constructed. For systems larger than the screening length, we obtain an analog of the homogenization result of Niethammer & Otto [B. Niethammer, F. Otto, Ostwald ripening: The screening length revisited, Calc. Var. Partial Differential Equations 13-1 (2001) 33-68]. A separation of timescales between particle growth and migration allows for a variational characterization of spatially inhomogeneous quasi-equilibrium states.

Glasner, Karl; Choksi, Rustum

2009-07-01

155

Hygroscopicity of Amine Secondary Aerosol - Mixtures of Organic and Inorganic Components  

NASA Astrophysics Data System (ADS)

Aliphatic amines are emitted from both biogenic and anthropogenic sources and contribute to the formation of secondary aerosol in reactions with atmospheric radicals. However, the cloud condensation nuclei (CCN) ability of amine aerosol has not been explored yet. Here, we study the hygroscopicity of aerosol formed from three aliphatic amines (trimethylamine, diethylamine and butylamine) in the UCR environmental chamber. Amines can react with NO3, a dominant night time oxidant in acid-base and/or oxidation reactions. The mass fraction of organic and inorganic components of formed aerosol was measured by Particle-into-Liquid Sampler coupled to dual ion chromatographs (PILS-ICs) and Scanning Mobility Particle Sizer (SMPS). CCN counter was used to measure the water-uptake ability of these particles. Significantly high hygroscopicity (?>0.3) was observed for aerosols formed from diethylamine and butylamine with NO3 radicals, which comprised >40% inorganic salt. Compared with amines oxidized by hydroxyl radicals, the presence of aminium salts formed in acid-base reactions greatly improved CCN activity of NO3-initiated aerosol. The effect of water vapor on the formation of aminium salts and aerosol hygroscopicity was also studied. Our results will significantly impact the estimation and role of amines in atmospheric chemistry and global climate models.

Tang, X.; Cocker, D. R.; Purvis-Roberts, K.; Asa-Awuku, A. A.

2012-12-01

156

Solubility of hydrophobic surfactant proteins in organic solvent/water mixtures. Structural studies on SP-B and SP-C in aqueous organic solvents and lipids.  

PubMed

The solubility of hydrophobic pulmonary surfactant proteins in different organic solvents and organic solvent/water combinations has been analyzed. Three organic solvents have been selected: methanol (MetOH), acetonitrile (ACN) and trifluoroethanol (TFE). Porcine SP-B showed very similar calculated secondary structure when dissolved in methanol, 60% ACN or 70% TFE and reconstituted in lysophosphatidylcholine (LPC) micelles or dipalmitoylphosphatidylcholine (DPPC) vesicles, as deduced from circular dichroism studies. SP-B was calculated to possess around 45% of alpha-helix in all these systems. The fluorescence emission spectrum of SP-B has been also characterized in aqueous solvents and lipids. It always showed a splitting of the tryptophan contribution into two components with different emission maxima. SP-C had a very different structure in 80% ACN or 70% TFE. While alpha-helix was the main secondary structure of SP-C in ACN/water mixtures--around 50%--, it had almost exclusively beta-structure when dissolved in 70% TFE. The CD spectrum of SP-C in TFE showed dependence on the protein concentration, suggesting that protein-protein interactions could be important in this beta-conformation. SP-C reconstituted in LPC micelles or DPPC vesicles had a CD spectrum qualitatively similar to that one in aqueous ACN, with a dominant alpha-helical structure. The alpha-helical content of SP-C in micelles of LPC and vesicles of DPPC, 60 and 70%, respectively, was calculated to be higher than the alpha-helical content of the protein dissolved in any aqueous organic solvent. PMID:8323965

Pérez-Gil, J; Cruz, A; Casals, C

1993-07-01

157

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

NASA Astrophysics Data System (ADS)

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 and variational 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 are evaluated numerically for application to a study of white-dwarf evolution.

Iyetomi, Hiroshi; Ogata, Shuji; Ichimaru, Setsuo

1989-07-01

158

A Comparison of delO18 Composition of Water Extracted from Suction Lysimeters, Centrifugation, and Azeotropic Distillation  

NASA Astrophysics Data System (ADS)

Concentration of delO18 in water samples extracted by suction lysimeters is compared to samples obtained by methods of centrifugation and azeotropic distillation. Intact soil cores (30 cm diameter by 40 cm height) were extracted from two different sites. Site 1 was rapid infiltration basin number 50, near Altamonte Springs in Seminole County, Florida on properties belonging to the Walt Disney World Resort Complex. Site 2 was the Missouri Management System Evaluation Area (MSEA) near Centralia in Boone County, Missouri. The delO18 water was analyzed on a mass spectrophotometer. Potassium Bromide (KBr) was also used as a tracer and analyzed by ion chromatography. A portion of the data obtained was modeled using CXTFIT. Water collected by centrifugation and azeotropic distillation data were about 2-5% more negative than that collected by suction lysimeter values from the Florida (sandy) soil and about 5-7 % more negative from the Missouri (well structured clay) soil. Results indicate that the majority of soil water in well structured soil is strongly bound to soil grain surfaces and is not easily sampled by suction lysimeters. Also, it is plausible that evaporation caused some delO18 enrichment in the suction lysimeters. Suction lysimeters preferentially sampled water held at lower matric potentials, which may not represent total soil water. In cases where a sufficient volume of water has passed through the soil profile and displaced all previous pore water, suction lysimeters will however collect a representative sample of all the water at that depth interval. It is suggested that for stable isotope studies monitoring precipitation and soil water, suction lysimeters be installed at shallow depths (10 cm). Samples should also be coordinated with precipitation events. The CXTFIT program worked well for Florida soils (a more homogeneous sand), but gave poor performance for Missouri soils (well structured clays) except for deeper depths where clay structure was less variable. The data also suggest that each extraction method samples a separate component of soil-pore water. Consequently, centrifugation can be used with good success, particularly for efficient sampling of large areas. Azeotropic distillation is more appropriate when strict qualitative and quantitative data for desorption, desorption, and various types of kinetic studies are needed.

Figueroa, A.; Tindall, J. A.; Friedel, M. J.

2005-12-01

159

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

160

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

161

Influence of the organic component on the geometry and stability of Dy(III) complexes with benzoic and aminobenzoic acids in water-80 vol % DMSO (DMFA) mixtures  

SciTech Connect

The stability and structure of dysprosium (III) benzoate and aminobenzoate complexes are estimated pH-metrically and magnetooptically in water and water-80 vol% DMSO (DMFA) mixtures. The factors responsible for the structural and stability changes that take place upon transition from water to water-organic solvents are discussed.

Kondrashina, Y.G.; Mustafina, A.R.; Devyatov, F.V. [Arbuzov Institute of Organic and Physical Chemistry, Tatarstan (Russian Federation)] [and others

1995-07-01

162

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

EPA Science Inventory

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

163

Effects of a mixture of organisms, Lactobacillus acidophilus or Streptococcus faecalis on cholesterol metabolism in rats fed on a fat- and cholesterol-enriched diet.  

PubMed

The effect of a mixture of organisms (a probiotic mixture) comprising Bacillus, Lactobacillus, Streptococcus, Clostridium, Saccharomyces and Candida (10(7-8) colony-forming units/g rice bran of each component) on lipid metabolism was compared with that of L. acidophilus and that of S. faecalis. There were four treatment groups: rice bran (control), the mixture of organisms, L. acidophilus or S. faecalis (30 g/kg) were given to rats in a fat- and cholesterol-enriched diet for 4 weeks. The serum total cholesterol concentration of the group fed on the mixture of organisms was reduced by 15-33% compared with the other groups at the end of the 4-week feeding period (P < 0.05). This group also had a lower hepatic cholesterol concentration (36-44%) than the two single-bacteria groups (P < 0.05). 3-Hydroxy-3-methylglutaryl-Co A reductase (NADPH; EC 1.1.1.34) activities of the mixed-organism and L. acidophilus groups were significantly lower (61-63%) than those of the other groups (P < 0.05); the activity of the S. faecalis group was also significantly lower (42%) than that of the control group (P < 0.05). The faecal cholesterol and bile acid concentrations of the mixed-organism group increased compared with those of the L. acidophilus and S. faecalis groups (P < 0.05). The capacity of the mixed-organism cells to bind bile salt in vitro was significantly higher (approximately 50%) than that of the single-bacteria cells (P < 0.05). On the other hand, cholesterol micelle formation for the mixed-organism cells was significantly (approximately 9%) lower than that of the single-bacteria cells (P < 0.05). These results indicate that the mixture of organisms decreased the synthesis of cholesterol in the liver and increased the loss of steroids from the intestine, in rats. Thus, the mixture of organisms had a hypocholesterolaemic role. PMID:9014654

Fukushima, M; Nakano, M

1996-12-01

164

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

165

Quantitative structure-activity relationships and mixture toxicity of organic chemicals in Photobacterium phosphoreum: the Microtox test  

SciTech Connect

Quantitative structure-activity relationships were calculated for the inhibition of bioluminescence of Photobacterium phosphoreum by 22 nonreactive organic chemicals. The inhibition was measured using the Microtox test and correlated with the partition coefficient between n-octanol and water (Poct), molar refractivity (MR), and molar volume (MW/d). At log Poct less than 1 and greater than 3, deviations from linearity were observed. Introduction of MR and MW/d improved the quality of the relationships. The influences of MR or MW/d may be related with an interaction of the tested chemicals to the enzyme system which produces the light emission. The sensitivity of the Microtox test to the 22 tested compounds is comparable to a 14-day acute mortality test with guppies for chemicals with log Poct less than 4. The inhibition of bioluminescence by a mixture of the tested compounds was slightly less than was expected in case of concentration addition. The Microtox test can give a good estimate of the total aspecific minimum toxicity of polluted waters. When rather lipophilic compounds or pollutants with more specific modes of action are present, this test will underestimate the toxicity to other aquatic life.

Hermens, J.; Busser, F.; Leeuwangh, P.; Musch, A.

1985-02-01

166

Effects of mixtures of persistent organic pollutants (POPs) derived from cod liver oil on H295R steroidogenesis.  

PubMed

Crude cod liver oil and liver oil supplements are consumed as a source of vitamin A, D and polyunsaturated fatty acids; during winter and early pregnancy. Crude cod liver oil however constitutes a considerable source of persistent organic pollutants (POPs). This paper aimed at characterizing and quantifying the influence of POP mixtures extracted from three different steps in the cod liver oil industrial process on hormone production and the expression of steroidogenesis-related genes in H295R cells. Exposure to extracts from crude cod liver oil and from its industrial waste increased progesterone (P4), cortisol (Cort), testosterone (T) and estradiol (E2) production; and among others, the expression of MC2R, CYP11B1 and HSD3B2 genes. Observed effects after exposure to pharmaceutical cod liver oil extract were considerably lower. The type of effects on gene expression and hormone production were similar to those induced by forskolin and PCBs, the latter being the major contaminants within the extracts. Additional research is required to further unveil the mechanisms behind the observed steroidogenic effects and to assess whether the potential risk might outweigh the potential benefits of crude and processed cod liver oil consumption. PMID:21722693

Montaño, M; Zimmer, K E; Dahl, E; Berg, V; Olsaker, I; Skaare, J U; Murk, A J; Ropstad, E; Verhaegen, S

2011-09-01

167

Organic chemistry of NH3 and HCN induced by an atmospheric abnormal glow discharge in N2-CH4 mixtures  

NASA Astrophysics Data System (ADS)

The formation of the chemical products produced in an atmospheric glow discharge fed by a N2-CH4 gas mixture has been studied using Fourier Transform InfraRed (FTIR) and Optical Emission Spectrometry (OES). The measurements were carried out in a flowing regime at ambient temperature and pressure with CH4 concentrations ranging from 0.5% to 2%. In the recorded emission spectra the lines of the second positive system CN system and the first negative system of N2 were found to be the most intensive but atomic H?, H?, and C (247 nm) lines were also observed. FTIR-measurements revealed HCN and NH3 to be the major products of the plasma with traces of C2H2. These same molecules have been detected in Titan's atmosphere and the present experiments may provide some novel insights into the chemical and physical mechanisms prevalent in Titan's atmosphere with these smaller species believed to be the precursors of heavier organic species in Titan's atmosphere and on its surface.

Horvath, G.; Krcma, F.; Polachova, L.; Klohnova, K.; Mason, N. J.; Zahoran, M.; Matejcik, S.

2011-01-01

168

Response of portable VOC (volatile organic compounds) analyzers to chemical mixtures. Final report Dec 80-May 81  

SciTech Connect

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 chemicals are presented. Various empirical models were evaluated to determine an appropriate method of estimating mixture concentration based on instrument response. The evaluation concluded that the instrument response for a mixture falls between the responses expected for the pure compounds in the mixture. Thus, an interpolation or weighted average model can be used to predict the response for mixtures based on known responses for individual chemicals. Both linear and logarithmic weighted average models are applied to the data and presented with estimates of accuracy. In general, these models predicted the instrument response to within 30% of the observed value.

DuBose, D.A.; Brown, G.E.; Harris, G.E.

1981-06-01

169

Tube Radial Distribution Phenomenon with a Two-phase Separation Solution of a Fluorocarbon and Hydrocarbon Organic Solvent Mixture in a Capillary Tube and Metal Compounds Separation.  

PubMed

A fluorocarbon and hydrocarbon organic solvent mixture is known as a temperature-induced phase-separation solution. When a mixed solution of tetradecafluorohexane as a fluorocarbon organic solvent and hexane as a hydrocarbon organic solvent (e.g., 71:29 volume ratio) was delivered in a capillary tube that was controlled at 10°C, the tube radial distribution phenomenon (TRDP) of the solvents was clearly observed through fluorescence images of the dye, perylene, dissolved in the mixed solution. The homogeneous mixed solution (single phase) changed to a heterogeneous solution (two phases) with inner tetradecafluorohexane and outer hexane phases in the tube under laminar flow conditions, generating the dynamic liquid-liquid interface. We also tried to apply TRDP to a separation technique for metal compounds. A model analyte mixture, copper(II) and hematin, was separated through the capillary tube, and detected with a chemiluminescence detector in this order within 4 min. PMID:24919675

Kitaguchi, Koichi; Hanamura, Naoya; Murata, Masaharu; Hashimoto, Masahiko; Tsukagoshi, Kazuhiko

2014-01-01

170

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

NASA Astrophysics Data System (ADS)

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

2014-03-01

171

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

EPA Science Inventory

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

172

Application of Steam Flushing to Removal of a DNAPL Mixture of Volatile and Very Low Volatility Organic Compounds  

Microsoft Academic Search

A laboratory study was performed to assess the effectiveness of steam flushing for removal of a dense nonaqueous phase liquid (DNAPL) mixture of monochlorobenzene (MCB) and DDT. MCB has a boiling point of 131 C, while DDT has a melting point of approximately 110 C, but is soluble in MCB. In the study 600 mL of a MCB-DDT DNAPL mixture

B. E. Sleep; Z. Zhang

2009-01-01

173

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

174

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

PubMed

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 different forms of nitrogen during composting depended on the material which supplied the nitrogen to the mixtures and the organic matter (OM) degradation rate during composting. The greatest concentration of ammonium was observed during the first weeks of composting, coinciding with the most intense period of OM degradation, and ammonium then decreased gradually to reach final values of below 0.04%. The use of urea as a nitrogen source in the mixtures led to high ammonium levels during the first weeks as a result of its rapid hydrolysis. The nitrification process began only when the temperature of the mixtures had dropped below 40 degrees C and its intensity depended on the quantity of ammonium present when the process began. The highest concentrations of NO3-N were always produced at the end of maturation, reaching values of 0.52%, 0.53%, 0.12% and 0.20% in the four mixtures studied. Nitrogen losses during composting depended on the materials used and on the pH values of the mixtures. Mixtures with the highest lignocellulose content showed the lowest losses (below 25%), while those containing municipal solid waste lost more than 40% of the initial content. Statistically significant correlations at a high probability level were found between the NO3-N concentration and pH and electrical conductivity. confirming that nitrification was responsible for the falling pH values and increasing electrical conductivity. The ratio of NH4-N and NO3-N concentrations was shown to be a clear indicator of the maturity of the mixtures during composting, the final values of 0.08, 0.04, 0,16 and 0.11 for the four mixtures being equal to, or below the maximum value established as a maturity index in other materials. PMID:11341692

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

2001-07-01

175

Pervaporative separation of ethanol\\/water azeotrope using a novel chitosan-impregnated bacterial cellulose membrane and chitosan–poly(vinyl alcohol) blends  

Microsoft Academic Search

The pervaporative (PV) performance with respect to the separation of ethanol\\/water (EtOH\\/H2O) azeotrope was assessed for a bacterial cellulose membrane (BCM) impregnated with chitosan (CTSN), designated as CTSN–BCM. The PV potential of CTSN–BCM was compared with that of parent polymers and also with the blends of CTSN with poly(vinyl alcohol) (PVA). The blends and CTSN–BCM were characterized using spectroscopic and

Vinita Dubey; Lokesh Kumar Pandey; Chhaya Saxena

2005-01-01

176

Isobaric vapor–liquid equilibrium for the binary mixtures of nonane with cyclohexane, toluene, m-xylene, or p-xylene at 101.3 kPa  

Microsoft Academic Search

The isobaric vapor–liquid equilibrium (VLE) data were determined, by using a recirculation type apparatus, for the binary mixtures of nonane with cyclohexane, toluene, m-xylene, or p-xylene at 101.3kPa. All the data passed the thermodynamic consistency test and no azeotrope was formed in the investigated binary systems. While nonane+p-xylene were found to behave as near ideal systems, nonane+cyclohexane, nonane+toluene, and nonane+m-xylene

Bhupender S. Gupta; Ming-Jer Lee

177

Isobaric vapor–liquid equilibrium for binary mixtures of 1-hexene + n-hexane and cyclohexane + cyclohexene at 30, 60 and 101.3 kPa  

Microsoft Academic Search

Consistent vapor–liquid equilibria (VLE) data were determined for the binary systems 1-hexene+n-hexane and cyclohexane+cyclohexene at 30, 60 and 101.3kPa, with the purpose of studying the influence of the pressure in the separation of these binary mixtures. The two systems show a small positive deviation from ideality and do not present an azeotrope. VLE data for the binary systems have been

Beatriz Marrufo; Antonio Aucejo; Margarita Sanchotello; Sonia Loras

2009-01-01

178

External electron ionization 7 T Fourier transform ion cyclotron resonance mass spectrometer for resolution and identification of volatile organic mixtures  

Microsoft Academic Search

An external electron ionization (EI) source has been interfaced to a 7 T Fourier transform ion cyclotron resonance mass spectrometer and tested for volatile complex mixture analysis. A new Sulfinert®-deactivated inlet system provides continuous stable sample flow to the EI source, leading to stable ion signal (±10% deviation) for 2 h from a 200 nL mixture of 15 n-alkylbenzenes. Ultrahigh-mass

Jinmei Fu; Jeremiah M Purcell; John P. Quinn; Tanner M. Schaub; Christopher L. Hendrickson; Ryan P. Rodgers; Alan G. Marshall

2006-01-01

179

External electron ionization 7 T Fourier transform ion cyclotron resonance mass spectrometer for resolution and identification of volatile organic mixtures  

Microsoft Academic Search

An external electron ionization (EI) source has been interfaced to a 7 T Fourier transform ion cyclotron resonance mass spectrometer and tested for volatile complex mixture analysis. A new Sulfinert®-deactivated inlet system provides continuous stable sample flow to the EI source, leading to stable ion signal (+\\/-10% deviation) for 2 h from a 200 nL mixture of 15 n-alkylbenzenes. Ultrahigh-mass

Jinmei Fu; Jeremiah M. Purcell; John P. Quinn; Tanner M. Schaub; Christopher L. Hendrickson; Ryan P. Rodgers; Alan G. Marshall

2006-01-01

180

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

Microsoft Academic Search

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

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

2011-01-01

181

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

Microsoft Academic Search

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

Ulrich von Pidoll

2008-01-01

182

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

183

Morphology-dependent exciton emission and energy transfer in fluorene-polymer-related fluorescent and phosphorescent composite films spin cast from a mixture of two dissimilar organic solvents  

SciTech Connect

We report morphology-dependent exciton emission and energy transfer in fluorene-conjugated polymer poly(9,9-dioctylfluorenyl-2,7-diyl)-related fluorescent and phosphorescent materials by using a mixture of two dissimilar organic solvents for spin-cast film formation. The electron microscopic characterizations revealed that the mixture of a high-boiling-point orthodichlorobenzene and a low-boiling-point chloroform results in a formation of both crystalline and amorphous morphological structures in fluorene-conjugated polymers. The UV-visible absorption and photoluminescence studies indicated that the low-energy crystalline phase domains, randomly distributed in the continuous high-energy amorphous phase, function as potential quantum wells. As a consequence, the mixture of two dissimilar organic solvents significantly affects the exciton emission from fluorescent fluorene-conjugated polymer and the energy transfer in phosphorescent composite of fluorene polymer and iridium complex molecules, presenting a pathway to control fluorescent and phosphorescent processes in polymer light-emitting materials.

Wu, Yue [University of Tennessee, Knoxville (UTK); Hu, Bin [University of Tennessee, Knoxville (UTK); Howe, Jane Y [ORNL

2005-01-01

184

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 ...

185

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

186

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

187

The improvement of polyaniline glucose biosensor stability using enzyme immobilization from water–organic mixtures with a high content of organic solvent  

Microsoft Academic Search

Immobilization of a glucose oxidase (GOD) into Nafion membranes is proposed by suspending the enzyme in a water–ethanol mixture with a high (>90%) ethanol content, mixing with the polyelectrolyte solution, and drying at the target surface. Since Nafion was deposited from its real solution without excessive dissolving with water, the resulting membranes were more uniform and stable. The enzyme suspension

Lilia V Lukachova; Arkady A Karyakin; Elena E Karyakina; Lo Gorton

1997-01-01

188

Two-phase flow heat transfer of binary mixtures inside enhanced surface tubing  

SciTech Connect

The primary heat transfer parameters such as coefficient of heat transfer and pressure drop observed during condensation of binary azeotropic refrigerant mixtures R-41Oa (R25/R32: 50/50), and R-507 (R125/R143a: 50/50) are presented in this paper. Experiments showed that for Reynolds numbers higher than 4.2 E06, R-410a appears to have greater heat transfer rates more than the other blends under investigation. Furthermore, it is quite evident from this data that R-507 has the highest pressure drop among the refrigerants under investigation.

Sami, S.M.; Poirier, B. [Univ. of Moncton, New Brunswick (Canada)] [Univ. of Moncton, New Brunswick (Canada)

1998-08-01

189

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...

190

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

Microsoft Academic Search

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

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

1998-01-01

191

Molecular organization and aggregation in Langmuir and Langmuir-Blodgett films of azo dye/liquid crystal mixtures  

NASA Astrophysics Data System (ADS)

A study of azo dye/liquid crystal mixtures in monolayers formed at air-water (Langmuir films) and air-solid substrate (Langmuir-Blodgett films) interfaces was performed. Three azo dyes with various molecular structure and two liquid crystal materials: 4-octyl-4'-cyanobiphenyl (8CB) and trans-4-octyl(4'-cyanophenyl)-cyclohexane (8PCH) were used. The morphology of Langmuir films was monitored by means of a Brewster angle microscope (BAM). Moreover, a surface pressure and electronic absorption spectra of the monolayer spread on the water surface of dye/liquid crystal mixtures as a function of a mean molecular area were simultaneously recorded. In addition, the absorption for Langmuir-Blodgett films deposited on quartz plates was measured. Information about intermolecular interactions in the mixtures of the nonamphiphilic dye and the liquid crystal with polar terminal group was obtained. Conclusions about the formation of self-aggregates between dye molecules have been drawn. The influence of the dye molecular structure and its concentration on aggregates’ geometry was found.

Inglot, K.; Marty?ski, T.; Bauman, D.

2009-06-01

192

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

NASA Astrophysics Data System (ADS)

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

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

2005-12-01

193

Integrating effects of stressors across levels of biological organization: examples using organophosphorus insecticide mixtures in field-level exposures  

Microsoft Academic Search

An important uncertainty often identified inecological risk assessment is the lack of ecologicalconnectivity between endpoints measured across themany levels of biological organization within anecosystem. In the present study, we address thisissue by quantitatively linking acetylcholinesterase(AChE) activity, a common biomarker of exposure toorganophosphorus (OP) insecticides, with endpoints athigher levels of biological organization in fish andinvertebrates, and to assess the utility of

P. K. Sibley; M. J. Chappel; T. K. George; K. R. Solomon; K. Liber

2000-01-01

194

EFFICIENCY OF THREE REACTIVE MIXTURES OF ORGANIC WASTES FOR THE TREATMENT OF HIGHLY CONTAMINATED ACID MINE DRAINAGE  

Microsoft Academic Search

Passive bioreactors involving sulphate-reducing bacteria (SRB) are a reasonable alternative technology for acid mine drainage (AMD) treatment. To be effective, they need a biodegradable organic carbon source and a favourable biogeochemical environment. However, long-term performance can be limited by the bioavailability of organic carbon. The study intended to find the key parameters that link substrate composition with its biodegradability and

C. Neculita; G. J. Zagury; B. Bussière

195

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 solutionsâand atoms and moleculesâcan 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 tableâone 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

196

Role of organic additives on non-aqueous tape casting of SiAlON ceramics  

Microsoft Academic Search

Suspensions consisting of precursor ?\\/? SiAlON forming powders, azeotropic solvent mixture of 60MEK\\/40E, dispersant, binder, and plasticizer were optimized for tape casting by rheological measurements and tape properties. Sodium tripolyphosphate (STPP) was introduced as a dispersant for low temperature applications of ?\\/?-SiAlONs. Optimum STPP amount was determined as 0.012g\\/m2 (of the particle surface) for stable ?\\/?-SiAlON suspensions. Different amounts of

Ali Ceylan; Ender Suvaci; Hasan Mandal

2011-01-01

197

IUPAC-NIST Solubility Data Series. 102. Solubility of Nonsteroidal Anti-inflammatory Drugs (NSAIDs) in Neat Organic Solvents and Organic Solvent Mixtures  

NASA Astrophysics Data System (ADS)

Solubility data are compiled and reviewed for 33 nonsteroidal anti-inflammatory drugs dissolved in neat organic solvents and in well-defined binary and ternary organic solvents. The compiled solubility data were retrieved primarily from the chemical and pharmaceutical literature covering the period from 1980 to the beginning of 2014.

Acree, William E.

2014-06-01

198

Application of Steam Flushing to Removal of a DNAPL Mixture of Volatile and Very Low Volatility Organic Compounds  

NASA Astrophysics Data System (ADS)

A laboratory study was performed to assess the effectiveness of steam flushing for removal of a dense nonaqueous phase liquid (DNAPL) mixture of monochlorobenzene (MCB) and DDT. MCB has a boiling point of 131 C, while DDT has a melting point of approximately 110 C, but is soluble in MCB. In the study 600 mL of a MCB-DDT DNAPL mixture was injected into a medium sand layer above a capillary barrier (silt) in a cell of dimension 110 cm long by 60 cm high by 10 cm thick. After the DNAPL became immobilized as a pool on the capillary barrier steam was flushed through the system at an inlet temperature of 135 C and a pressure of 100 kPa, to represent removal of DNAPL from approximately 10 m below the water table. Approximately 3.5 pore volumes of steam (as condensate) were flushed through the DNAPL zone above the capillary barrier over an 11 hour period. Temperatures in the DNAPL zone exceeded the melting point of pure DDT and reached the boiling point of MCB. Initial DNAPL removal was due to hydraulic displacement (as indicated by DNAPL composition close to the source DNAPL composition), followed by primarily MCB removal by steam distillation. A total of 255 mL of DNAPL was recovered. Soil sampling following steam flushing showed levels of both MCB and DDT remaining in the original DNAPL zone that were consistent with the presence of DNAPL. Significant levels of MCB and DDT were also found below the capillary barrier, indicating that downward movement of MCB and DDT occurred, likely due to desaturation of the capillary barrier during steam flushing. In addition, heating to temperatures associated with significant depths below the water table enhances the mobility of the MCB-DDT DNAPL by reducing the DNAPL viscosity and preventing the solidification of DDT that might otherwise occur with MCB removal.

Sleep, B. E.; Zhang, Z.

2009-05-01

199

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

200

Use of Anion Exchange Resin and Acidic-Organic Mixtures in the Separation of Na, Cs and Ba.  

National Technical Information Service (NTIS)

A systematic study was carried out on the adsorption of Na, Cs and Ba on Dowex 1x8 from various concentrations of hydrochloric and nitric acid solutions. The addition of water-miscible organic solvents to the acidic solutions was found to increase the Ksu...

R. Shabana H. Ruf

1977-01-01

201

GAC ADSORPTION OF A MIXTURE OF NATURAL ORGANIC MATTER AND VOCS IN THE PRESENCE AND ABSENCE OF MOLECULAR OXYGEN  

EPA Science Inventory

In an attempt to determine the effects of molecular oxygen on activated carbon adsorption modeling; isotherms, microcolumns, and pilot-columns are completed in the presence and absence of molecular oxygen. he results show that in oxic conditions, natural organic matter has a high...

202

IUPAC-NIST Solubility Data Series. 98. Solubility of Polycyclic Aromatic Hydrocarbons in Pure and Organic Solvent Mixtures--Revised and Updated. Part 3. Neat Organic Solvents  

NASA Astrophysics Data System (ADS)

This work updates Vols. 54, 58, and 59 in the IUPAC Solubility Data Series and presents solubility data for polycyclic aromatic hydrocarbon solutes dissolved in neat organic solvents. Published solubility data for acenaphthene, anthracene, biphenyl, carbazole, dibenzofuran, dibenzothiophene, fluoranthene, fluorene, naphthalene, phenanthrene, phenothiazine, pyrene, thianthrene, and xanthene that appeared in the primary literature from 1995 to the end of 2011 are compiled and critically evaluated. Experimental solubility data for more than 550 different solute-organic solvent systems are included. Solubility data published prior to 1995 were contained in three earlier volumes (Vols. 54, 58, and 59) and are not repeated in this volume.

Acree, William E.

2013-03-01

203

Double-lift absorption refrigeration cycles driven by low–temperature heat sources using organic fluid mixtures as working pairs  

Microsoft Academic Search

At present, much interest is being shown in absorption refrigeration cycles driven by low temperature heat sources, such as solar energy or low-grade waste-heat. Double-lift absorption cycles working with ammonia-water have been recommended for refrigeration applications which require cold at 0°C and which are activated by waste heat between 70 and 100°C. This paper discusses the potential of the organic

M. Medrano; M. Bourouis; A. Coronas

2001-01-01

204

Sources and ages of dissolved organic matter in peatland streams: evidence from chemistry mixture modelling and radiocarbon data  

Microsoft Academic Search

Monitoring data over the period 1994–2007 were analysed for three streams (Cottage Hill Sike, CHS; Rough Sike, RS; Trout Beck,\\u000a TB) draining blanket peat underlain by glacial clay and limestone-rich sub-strata at Moor House (Northern England). Dissolved\\u000a organic carbon concentration, [DOC], showed complex relationships with both discharge and calcium concentration, [Ca]. A model\\u000a based on [Ca] was constructed to simulate

E. Tipping; M. F. Billett; C. L. Bryant; S. Buckingham; S. A. Thacker

2010-01-01

205

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

206

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

207

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

PubMed

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

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

2013-03-01

208

Co3(HCOO)6 microporous metal-organic framework membrane for separation of CO2/CH4 mixtures.  

PubMed

Continuous metal-organic framework-type Co(3)(HCOO)(6) intergrown films with a one-dimensional zigzag channel system and pore aperture of 5.5 Å are prepared by secondary growth on preseeded macroporous glass-frit disks and silicon wafers. The adsorption behavior of CO(2) or CH(4) single gases on the Co(3)(HCOO)(6) membrane is investigated by in situ IR spectroscopy. It is shown that the isosteric heats of adsorption for CO(2) (17.7 kJ mol(-1)) and CH(4) (14.4 kJ mol(-1)) do not vary with increasing amount of adsorbed gases. The higher value of isosteric heat for CO(2) is an indication of the stronger interaction between the CO(2) and the Co(3)(HCOO)(6) membrane. The Co(3)(HCOO)(6) membrane is studied by binary gas permeation of CO(2) and CH(4) at different temperatures (0, 25, and 60 °C). The membrane has CO(2)/CH(4) selectivity with a separation factor higher than 10, which is due to the unique structure and molecular sieving effect. Upon increasing the temperature from 0 to 60 °C, the preferred permeance of CO(2) over CH(4) is increased from 1.70×10(-6) to 2.09×10(-6) mol m(-2) s(-1) Pa(-1), while the separation factor for CO(2)/CH(4) shows a corresponding decrease from 15.95 to 10.37. The effective pore size of the Co(3)(HCOO)(6) material combined with the pore shape do not allow the two molecules to pass simultaneously, and once the CO(2) molecules are diffused in the micropores, the CH(4) is blocked. The supported Co(3)(HCOO)(6) membrane retains high mechanical stability after a number of thermal cycles. PMID:21922579

Zou, Xiaoqin; Zhang, Feng; Thomas, Sebastien; Zhu, Guangshan; Valtchev, Valentin; Mintova, Svetlana

2011-10-17

209

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

SciTech Connect

For the pure or azeotropic refrigerants typically used in present air conditioning and refrigeration applications, the refrigerant changes phase at a constant temperature. Thus, the refrigerant circuiting arrangement such as crossfiow, counterfiow, or cross-counterflow, has no effect on the thermal performance. For zeotropic refrigerant mixtures, however, the phase-change occurs over a temperature range, or "glide", and the refrigerant circuiting arrangement, or flow path through the heat exchanger, can affect the thermal performance of both the heat exchangers as well as the overall efficiency of the vapor compression cooling cycle. The effects of tsvo diflerent circuiting arrangements on the thermal performance of a zeotropic retligerant mixture and an almost azeotropic refrigerant mixture in a four-row cross-countertlow heat exchanger arrangement are reported here. The two condensers differ only in the manner of circuiting the refrigerant tubes, where one has refrigerant always flowing downward in the active heat transfer region ("identical order") and the other has refrigerant alternating flow direction in the active heat transfer region ("inverted order"). All other geometric parameters, such as bce are% fin louver geometry, refrigerant tube size and enhancement etc., are the same for both heat exchangers. One refrigerant mixture (R-41OA) un&rgoes a small temperature change ("low glide") during phase change, and the other retligerant mixture (a multi- component proprietary mixture) has a substantial temperature change ("high glide") of approximately 10"C during the phase change process. The overall thermal conductance, two-phase conductance, and pressure drop are presented. For the flow conditions of these tests, which are representative of resi&ntial cooling conditions, inverted order circuiting is more desirable than identical order. The potential thermal advantages of the i&ntical order arrangement for high-glide zeotropic refrigerant mixtures are negated by the increased parasitic refrigerant-side pressure drop utiortunately resulting from tkbrication requirements of the identical order circuiting.

Chen, D.T.; Conklin, J.C.

1999-03-15

210

The use of cyprinodont fish, Aphanius fasciatus, as a sentinel organism to detect complex genotoxic mixtures in the coastal lagoon ecosystem.  

PubMed

In the present work we aimed to standardise the alkaline comet assay with erythrocytes of the cyprinodont, Mediterranean Killifish, Aphanius fasciatus. The aims of the study were to explore the suitability of this fish to assess biomarkers of genotoxic effects and as a sentinel organism to detect complex genotoxic mixtures in coastal lagoon ecosystems. Following proper optimisation, the application and effectiveness of the comet assay in erythrocytes of A. fasciatus were tested by measuring the tail DNA (%) induced by (a) in vivo exposure of individual fish to X-rays (dose, 3Gy) and (b) following in vitro challenge of erythrocytes with restriction endonucleases Fok-I and Eco-RI, which selectively induce double-strand breaks with cohesive and blunt termini, respectively. Furthermore, in order to evaluate whether circulating fish blood contained actively proliferating cells that could influence the extent of DNA damage in control (untreated) fish, we measured the number of "comets" positive for 5-bromo-2'-deoxyuridine (BrdU) by the use of anti-BrdU antibody and immuno-histochemical methods. Both treatments (i.e. with X-rays and restriction endonucleases) induced statistically significant increases in tail DNA (%) values compared with the relevant untreated controls, indicating the effectiveness of the comet assay in the erythrocytes of A. fasciatus to detect different types of DNA lesions. Results from anti-BrdU antibody labelling of erythrocytes indicated a very low percentage (5%) of "comets" positive for BrdU. Following optimisation and validation of the assay under laboratory conditions, fish were collected in the Orbetello lagoon (Tuscany, Italy), considered to be a significantly polluted site. The results showed statistically significant increases for tail DNA (%) compared with corresponding values observed in erythrocytes of fish caught in the unpolluted reference site "Saline di Tarquinia". The effects of physico-chemical parameters of the water (i.e., salinity, pH and oxygen content) did not significantly influence the induction of DNA damage. These results indicate that the comet assay provides a reliable parameter and that A. fasciatus is a promising "sentinel organism" to detect the genotoxic impact of complex mixtures in coastal lagoon ecosystems. PMID:22222993

Mosesso, Pasquale; Angeletti, Dario; Pepe, Gaetano; Pretti, Carlo; Nascetti, Giuseppe; Bellacima, Raffaela; Cimmaruta, Roberta; Jha, Awadhesh N

2012-02-18

211

Heat transfer in nucleate boiling of R134a/R152a mixtures  

NASA Astrophysics Data System (ADS)

Heat transfer coefficients were measured on a horizontal platinum wire and converted to data on horizontal copper tubes. The measurements spanned a large region of pressures p* = p/pcrit = 0.05-0.50 and heat fluxes of q = 103-1.5 × 105 W/m2. The preparation of the test equipment is described. The effects of pressure and concentration on the heat transfer coefficients are shown. The mixture behaves very much like an azeotropic mixture; concentration has only a small effect, the heat transfer coefficients can be obtained from the heat transfer coefficients of the pure components according to their molar fractions. The conversion steps from wire- to tube-data are presented. A comparison of wire-data with correlations given in literature is shown. It renders good agreement.

Shi, Kehong; Spindler, Klaus; Hahne, Erich

2010-11-01

212

Microscopic observation of ordered colloids in sedimentation equilibrium and important role of Debye-screening length. VI. Organic solvent aqueous mixtures for heavy and monodisperse spheres (specific gravity=1.50)  

Microsoft Academic Search

A metallurgical microscope is used to directly observe the ordered structures of heavy and monodisperse polystyrene-type spheres (specific gravity=1.50) in sedimentation equilibrium and in organic solvent aqueous mixtures. Eight kinds of water miscible organic solvents, i.e., methanol, ethanol, propanol, 1,4-dioxane, ethylene glycol, propylene glycol, N-methylformamide (NMF), and N-methylacetamide (NMA) are used. The center-to-center interparticle distances (D) in the hexagonal ordering

Tsuneo Okubo

1988-01-01

213

Separating Mixtures  

NSDL National Science Digital Library

In this lesson the students will learn how to classify the materials as mixtures, elements and compounds and identify the properties of each group. Also the concept of separation of mixtures will be introduced to the students. Since barring a few exceptions, almost every element or compound is found naturally in an impure state such as a mixture of two or more substances. Many times the need to separate it into its individual components arises and chemical engineers use separation techniques to do this. Separation applications in the field of chemical engineering are very important. A good example is that of crude oil. Crude oil is a mixture of various hydrocarbons and is valuable in this natural form. Demand is greater, however, for the purified various hydrocarbons such as natural gases, gasoline, diesel, jet fuel, lubricating oils, asphalt, etc.

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

214

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

NASA Astrophysics Data System (ADS)

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

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

2010-10-01

215

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

216

Organic  

NSDL National Science Digital Library

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

2007-12-07

217

New and extended parameterization of the thermodynamic model AIOMFAC: calculation of activity coefficients for organic-inorganic mixtures containing carboxyl, hydroxyl, carbonyl, ether, ester, alkenyl, alkyl, and aromatic functional groups  

NASA Astrophysics Data System (ADS)

We present a new and considerably extended parameterization of the thermodynamic activity coefficient model AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients) at room temperature. AIOMFAC combines a Pitzer-like electrolyte solution model with a UNIFAC-based group-contribution approach and explicitly accounts for interactions between organic functional groups and inorganic ions. Such interactions constitute the salt-effect, may cause liquid-liquid phase separation, and affect the gas-particle partitioning of aerosols. The previous AIOMFAC version was parameterized for alkyl and hydroxyl functional groups of alcohols and polyols. With the goal to describe a wide variety of organic compounds found in atmospheric aerosols, we extend here the parameterization of AIOMFAC to include the functional groups carboxyl, hydroxyl, ketone, aldehyde, ether, ester, alkenyl, alkyl, aromatic carbon-alcohol, and aromatic hydrocarbon. Thermodynamic equilibrium data of organic-inorganic systems from the literature are critically assessed and complemented with new measurements to establish a comprehensive database. The database is used to determine simultaneously the AIOMFAC parameters describing interactions of organic functional groups with the ions H+, Li+, Na+, K+, NH4+, Mg2+, Ca2+, Cl-, Br-, NO3-, HSO4-, and SO42-. Detailed descriptions of different types of thermodynamic data, such as vapor-liquid, solid-liquid, and liquid-liquid equilibria, and their use for the model parameterization are provided. Issues regarding deficiencies of the database, types and uncertainties of experimental data, and limitations of the model, are discussed. The challenging parameter optimization problem is solved with a novel combination of powerful global minimization algorithms. A number of exemplary calculations for systems containing atmospherically relevant aerosol components are shown. Amongst others, we discuss aqueous mixtures of ammonium sulfate with dicarboxylic acids and with levoglucosan. Overall, the new parameterization of AIOMFAC agrees well with a large number of experimental datasets. However, due to various reasons, for certain mixtures important deviations can occur. The new parameterization makes AIOMFAC a versatile thermodynamic tool. It enables the calculation of activity coefficients of thousands of different organic compounds in organic-inorganic mixtures of numerous components. Models based on AIOMFAC can be used to compute deliquescence relative humidities, liquid-liquid phase separations, and gas-particle partitioning of multicomponent mixtures of relevance for atmospheric chemistry or in other scientific fields.

Zuend, A.; Marcolli, C.; Booth, A. M.; Lienhard, D. M.; Soonsin, V.; Krieger, U. K.; Topping, D. O.; McFiggans, G.; Peter, T.; Seinfeld, J. H.

2011-09-01

218

New and extended parameterization of the thermodynamic model AIOMFAC: calculation of activity coefficients for organic-inorganic mixtures containing carboxyl, hydroxyl, carbonyl, ether, ester, alkenyl, alkyl, and aromatic functional groups  

NASA Astrophysics Data System (ADS)

We present a new and considerably extended parameterization of the thermodynamic activity coefficient model AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients) at room temperature. AIOMFAC combines a Pitzer-like electrolyte solution model with a UNIFAC-based group-contribution approach and explicitly accounts for interactions between organic functional groups and inorganic ions. Such interactions constitute the salt-effect, may cause liquid-liquid phase separation, and affect the gas-particle partitioning of aerosols. The previous AIOMFAC version was parameterized for alkyl and hydroxyl functional groups of alcohols and polyols. With the goal to describe a wide variety of organic compounds found in atmospheric aerosols, we extend here the parameterization of AIOMFAC to include the functional groups carboxyl, hydroxyl, ketone, aldehyde, ether, ester, alkenyl, alkyl, aromatic carbon-alcohol, and aromatic hydrocarbon. Thermodynamic equilibrium data of organic-inorganic systems from the literature are critically assessed and complemented with new measurements to establish a comprehensive database. The database is used to determine simultaneously the AIOMFAC parameters describing interactions of organic functional groups with the ions H+, Li+, Na+, K+, NH4+, Mg2+, Ca2+, Cl-, Br-, NO3-, HSO4-, and SO42-. Detailed descriptions of different types of thermodynamic data, such as vapor-liquid, solid-liquid, and liquid-liquid equilibria, and their use for the model parameterization are provided. Issues regarding deficiencies of the database, types and uncertainties of experimental data, and limitations of the model, are discussed. The challenging parameter optimization problem is solved with a novel combination of powerful global minimization algorithms. A number of exemplary calculations for systems containing atmospherically relevant aerosol components are shown. Amongst others, we discuss aqueous mixtures of ammonium sulfate with dicarboxylic acids and with levoglucosan. Overall, the new parameterization of AIOMFAC agrees well with a large number of experimental datasets. However, due to various reasons, for certain mixtures important deviations can occur. The new parameterization makes AIOMFAC a versatile thermodynamic tool. It enables the calculation of activity coefficients of thousands of different organic compounds in organic-inorganic mixtures of numerous components. Models based on AIOMFAC can be used to compute deliquescence relative humidities, liquid-liquid phase separations, and gas-particle partitioning of multicomponent mixtures of relevance for atmospheric chemistry or in other scientific fields.

Zuend, A.; Marcolli, C.; Booth, A. M.; Lienhard, D. M.; Soonsin, V.; Krieger, U. K.; Topping, D. O.; McFiggans, G.; Peter, T.; Seinfeld, J. H.

2011-05-01

219

Organization.  

ERIC Educational Resources Information Center

This theme issue on organization provides an annotated listing of Web sites, CD-ROMs and software, videos, books, and other resources related to organization to be used with K-8 students. Sidebars discuss being organized to be a good student, organizational identities, and organizing an election. Suggests student activities relating to…

Online-Offline, 1999

1999-01-01

220

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

221

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

222

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

Microsoft Academic Search

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

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

2011-01-01

223

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

224

Development of more efficacious Tc-99m organ imaging agents for use in nuclear medicine by analytical characterization of radiopharmaceutical mixtures  

SciTech Connect

Capillary electrophoresis is being evaluated as a separation technique for analyzing Tc and Re diphosphonate radiopharmaceuticals. Advantages compared with currently used HPLC techniques include greater resolving power, smaller sample size and more rapid separations. Feasibility has been demonstrated with electropherograms obtained on a Re-HEDP sample. The Tc-PAA complexes in a radiopharmaceutical mixture were found to be unaffected by injection into a Sprague Dawley rat. This was determined by HPLC analysis of the rat's urine, which contained the same complexes as were in the injected sample. Proton NMR spectra have been obtained for samples of Tc-MDP and Re-MDP in order to provide structural information about these complexes. An in vivo sensor is being developed for a brain perfusion agent. Polymer coatings are being explored to extract the brain perfusion agent in order to enhance sensitivity for a microelectrode-based sensor. 4 refs., 2 figs.

Heineman, W.R.

1991-04-01

225

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

226

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

227

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

228

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...

229

Extraction of metal salts by mixtures of water-immiscible amines and organic acids (acid-base couple extractants); 2: Theoretical treatment and analysis  

SciTech Connect

A comprehensive discussion is provided for the complex system obtained on equilibrating an aqueous solution of a salt with an acid-base couple (ABC) extractant. These extractants were analyzed as a combination of a liquid cation exchanger and a liquid anion exchanger operating concurrently. The effect of the amine on the organic acid activity and the effect of the acid on the amine activity were compared to those of mineral bases and acids on single active component extractants. The available distribution and spectroscopic data, summarized in the previous article, are discussed.

Eyal, A.M.; Bressler, E. (Hebrew Univ., Jerusalem (Israel)); Kogan, L. (Israel Mining Industry, Haifa (Israel))

1994-05-01

230

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

231

Inhibition of Listeria monocytogenes in full- and low-sodium frankfurters at 4, 7, or 10°C using spray-dried mixtures of organic acid salts.  

PubMed

In meat processing, powdered ingredients are preferred to liquids because of ease of handling, mixing, and storing. This study was conducted to assess Listeria monocytogenes inhibition and the physicochemical and organoleptic characteristics of frankfurters that were prepared with organic acid salts as spray-dried powders (sodium lactate-sodium acetate, sodium lactate-sodium acetate-sodium diacetate, and potassium acetate-potassium diacetate) or liquids (sodium lactate, sodium lactate-sodium diacetate, potassium lactate, and potassium lactate-sodium diacetate). Full-sodium (1.8% salt) and low-sodium (1.0% salt) frankfurters were prepared according to 10 and 5 different formulations (n = 3), respectively, and were dip inoculated with a six-strain cocktail of L. monocytogenes (?4 log CFU/g). Populations of Listeria and mesophilic aerobic bacteria were quantified during storage at 4, 7, and 10°C for up to 90 days. Four powder and two liquid full-sodium formulations and one powder low-sodium formulation, all of which contained diacetate except for 1% sodium lactate-sodium acetate powder, completely inhibited Listeria growth at 4°C. However, Listeria grew in full-sodium formulations at 10°C and in low-sodium formulations at 7 and 10°C except for the formulation containing 0.8% potassium acetate-0.2% potassium diacetate powder. All formulations were similar in terms of water activity, cooking yield, moisture, and protein content. Sodium content and pH were affected by the concentrations of sodium and diacetate, respectively. Frankfurter appearance, texture, flavor, and overall acceptability were similar (P > 0.05) regardless of the formulation, except for flavor and overall acceptability of the low-sodium formulation containing potassium acetate-potassium diacetate. Based on these findings, cosprayed powders appear to be a viable alternative to current liquid inhibitors for control of Listeria in processed meats. PMID:23992500

Sansawat, Thanikarn; Zhang, Lei; Jeong, Jong Y; Xu, Yanyang; Hessell, Gerald W; Ryser, Elliot T; Harte, Janice B; Tempelman, Robert; Kang, Iksoon

2013-09-01

232

Mixtures research at NIEHS: an evolving program.  

PubMed

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

2013-11-16

233

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.

234

Experimental analysis of a window air conditioner with R-22 and zeotropic mixture of R-32/125/134a  

SciTech Connect

This study is the result of the cooperative research and development agreement (CRADA) between Oak Ridge National Laboratory and E.I. Du Pont De Nemours and Company, Inc., (CRADA No. 92-0161) for testing the use of heat exchangers as the evaporator and condenser in an air-conditioning rig. Heat exchangers at typical realistic operating conditions were tested with R-22 and with its potential replacement, a ternary mixture of R-32(30%)/R-125(10%)/R-134a(60%). A test rig was built that provided for operation of the low-temperature exchanger (evaporator) with flooded coils. The test results indicated that the performance of the evaporator heat exchanger using ternary mixture, in terms of cooling capacity, would be around 7.4% less than the performance using R-22. The cooling capacity for both refrigerants improved with flooded evaporator operation by 8.6% for R-22 and by 15% for ternary mixture. Compared with R-22 operation, operation with ternary mixture results in slightly higher compressor discharge pressure, lower compressor discharge temperature, slightly lower compressor power consumption, and a higher compressor high-low pressure ratio. Temperature glide for ternary mixture, for both evaporator and condenser, was clearly evident, but not as pronounced as expected because of the pressure drop (and thus the temperature drop) along the coils. Further improvement of the performance of ternary mixture is possible if the evaporator is arranged in a counter-cross-flow configuration to take advantage of the temperature glide. Current evaporator designs are mostly concurrent-cross-flow, which is more appropriate for single-component refrigerants or azeotropic refrigerant mixtures.

Mei, V.C.; Chen, F.C.; Carlstedt, J.; Hallden, D.

1995-08-01

235

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).

Burns, Steve

2011-10-09

236

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

237

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.

Integrated Teaching And Learning Program

238

Dehydrochlorination of plastic mixtures  

Microsoft Academic Search

Dehydrochlorination of plastic mixtures from domestic waste as well as from other chlorine containing mixtures such as electronic scrap is an essential reaction step in waste incineration, pyrolysis and chemical recycling of polymers. For designing pyrolysis procedures, controlled combustion processes and to control the emissions from incinerators, the behaviour of polymers in thermal decomposition with regard to decomposition products and

H Bockhorn; A Hornung; U Hornung; P Jakobströer; M Kraus

1999-01-01

239

Symmetric normal mixtures  

NASA Technical Reports Server (NTRS)

We consider mixture density estimation under the symmetry constraint x = Az for an orthogonal matrix A. This distributional constraint implies a corresponding constraint on the mixture parameters. Focusing on the gaussian case, we derive an expectation-maximization (EM) algorithm to enforce the constraint and show results for modeling of image feature vectors.

Turmon, Michael

2004-01-01

240

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

241

Tissue residue approach for chemical mixtures.  

PubMed

At the SETAC Pellston Workshop "The Tissue Residues Approach for Toxicity Assessment," held in June 2007, we discussed mixture toxicology in terms of the tissue residue approach (TRA). This article reviews the literature related to the TRA for mixtures of chemicals and recommends a practical, tiered approach that can be implemented in regulatory or risk assessment applications. As with the toxicity of individual chemicals, addressing mixture toxicity by means of the TRA has a number of significant advantages. Early work provided a theoretical basis and experimental data to support the use of TRA for mixtures; later work provided a field-based validation of the integration. However, subsequent development has been hindered by the lack of mixture toxicity data expressed in tissue or preferably target-site concentrations. We recommend a framework for addressing the toxicology of mixtures that integrates the TRA and mixture toxicology in a 3-tier approach. Tier I uses concentration addition (CA) to estimate the toxicity of mixtures regardless of the mechanism of action of the components. However, the common approach that uses a bioaccumulation factor (BAF) to predict TR from the exposure-water concentration for organics must be modified slightly for metals because, unlike organics, the BAF for a metal changes as 1) the aqueous exposure concentration changes, and 2) the concentration of other metals changes. In addition, total tissue residues of a metal are not a good predictor of toxicity, because some organisms store high concentrations of metals internally in detoxified forms. In tier I, if the combination of measured concentrations in the mixture exceeds that predicted to produce adverse effects or above-reference levels, it is necessary to proceed to tier II. Tier II is a mixed model that employs CA and independent action to estimate mixture toxicity. Tiers I and II estimate the toxicity of mixtures to individual species. In tier III, the TRA is integrated with the multisubstance potentially affected fraction (ms-PAF) method to derive TR levels that are protective of a selected percentage of species in aquatic communities (e.g., hazardous concentration for 5% of the species [HC5]). PMID:21184571

Dyer, Scott; St J Warne, Michael; Meyer, Joseph S; Leslie, Heather A; Escher, Beate I

2011-01-01

242

Development of More Efficacious Tc-99M Organ Imaging Agents for Use in Nuclear Medicine by Analytical Characterization of Radiopharmaceutical Mixtures. Progress Report, May 1, 1980-April 30, 1981.  

National Technical Information Service (NTIS)

High performance liquid chromatography (HPLC) was used to efficiently separate and detect the individual components in a radiopharmaceutical mixture. A procedure for separating Tc(NaBH sub 4 )HEDP radiopharmaceutical analogues by anion exchange HPLC with ...

W. R. Heineman E. A. Deutsch

1980-01-01

243

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

244

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.

Damonte, Kathleen

2003-10-01

245

Summary Report. Adsorption Kinetics of Mixture Systems on Activated Carbon Beds.  

National Technical Information Service (NTIS)

Adsorption phenomena in such fields as purification and separation of gases, recovery of industrial solvents and respiratory protection is concerned with mixtures. Understanding the adsorption kinetics of mixtures of organic vapors on activated carbon bed...

J. Wu O. Claesson I. Faengmark

2001-01-01

246

Development of more efficacious Tc-99m organ imaging agents for use in nuclear medicine by analytical characterization of radiopharmaceutical mixtures. Final report, May 1, 1983-August 31, 1986  

SciTech Connect

/sup 99m/Tc-diphosphonate agents are not pure chemical species, but rather are complicated, time dependent, mixtures of as yet unidentified components. These mixtures can be separated by high performance liquid chromatography and that the separated components have significantly different biodistributions. The distribution of components is very sensitive to formulation conditions, and thus the variable image quality observed in clinical situations is not at all surprising. The conditions of a formulation can be manipulated to favor production of various components, and thus the properties of the entire mixture can be made to approach the properties of that component with the optimal biodistribution. This chemical fact can be used to advantage in developing more effective diagnostic and therapeutic bone agents. 139 refs., 10 figs., 1 tab.

Heineman, W.R.

1986-08-01

247

Mixtures and Solutions  

NSDL National Science Digital Library

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

Blind, Perkins S.

2012-06-26

248

Development of More Efficacious /Sup 99M/Tc Organ Imaging Agents for Use in Nuclear Medicine by Analytical Characterization of Radiopharmaceutical Mixtures. Progress Report, May 1, 1983-January 1, 1986.  

National Technical Information Service (NTIS)

The formation of many different technetium complexes in the Tc(NaBH sub 4 )-HEDP, Tc(NaBH sub 4 )-MDP, and Tc(NaBH sub 4 )-DMAD systems has been clearly demonstrated by HPLC-separation of reaction mixtures. The dramatically different biodistributions exhi...

W. R. Heineman

1986-01-01

249

Development of More Efficacious TC-99M Organ Imaging Agents for Use in Nuclear Medicine by Analytical Characterization of Radiopharmaceutical Mixtures. Progress Report, May 1, 1983-April 1, 1984.  

National Technical Information Service (NTIS)

It has been demonstrated that formulation variables (pH, TcO sub 4- concentration, and ligand-to-metal ratio) influence the chromatographic distribution of the components of a Tc-hydroxyethylidene diphosphonate (HEDP) mixture prepared by the NaBH sub 4 re...

W. R. Heineman

1984-01-01

250

Development of more efficacious TC-99M organ imaging agents for use in nuclear medicine by analytical characterization of radiopharmaceutical mixtures. Progress report, May 1, 1983-April 1, 1984  

SciTech Connect

It has been demonstrated that formulation variables (pH, TcO/sub 4//sup -/ concentration, and ligand-to-metal ratio) influence the chromatographic distribution of the components of a Tc-hydroxyethylidene diphosphonate (HEDP) mixture prepared by the NaBH/sub 4/ reduction of TcO/sub 4//sup -/ in the presence of HEDP. The use of alternate reductants for TcO/sub 4//sup -/ (i.e., SnCl/sub 2/, and electrode) not only alters the relative proportion of the Tc-HEDP components formed, but produces new complexes not previously seen (based on chromatographic retention time data). Thus, a systematic evaluation has been undertaken of the SnCl/sub 2/ and electrochemical reduction preparations that is similar to that conducted for Tc(NaBH/sub 4/)-HEDP mixtures. High performance liquid chromatography with electrochemical detection has been utilized to separate components of a Tc(NaBH4)-methylene diphosphonate mixture. All Tc components of the mixture are reducible at a mercury electrode and hydrodynamic voltammetric data is being generated. Stripping chronocoulometry has been developed as a novel variation of anodic stripping voltammetry in order to increase precision in the analytical determination of TcO/sub 4//sup -/ in aqueous solution. Pilot studies to evaluate the operating parameters of /sup 99/Mo//sup 99m/Tc/ generators and to investigate two new diphosphonate ligands in the preparation of technetium skeletal imaging radiopharmaceutical analogs have been initiated.

Heineman, W.R.

1984-01-01

251

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

252

Formation of 2-methyl tetrols and 2-methylglyceric acid in secondary organic aerosol from laboratory irradiated isoprene\\/NO X \\/SO 2\\/air mixtures and their detection in ambient PM 2.5 samples collected in the eastern United States  

Microsoft Academic Search

Recent observations in ambient PM2.5 of 2-methylthreitol, 2-methylerythritol and 2-methylglyceric acid, proposed isoprene oxidation products, suggest the contribution of isoprene to SOA formation, long thought to be relatively unimportant, should be reexamined. To address this issue, an isoprene\\/NOX\\/air mixture was irradiated in a flow reactor smog chamber in both the absence and presence of SO2 to measure the SOA yield

E. O. Edney; T. E. Kleindienst; M. Jaoui; M. Lewandowski; J. H. Offenberg; W. Wang; M. Claeys

2005-01-01

253

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

254

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

255

Purification of gas mixtures  

Microsoft Academic Search

The invention concerns a process for the purification of a hydrogen-containing gas mixture comprising up to 45% by volume of hydrogen, together with carbon oxides, hydrogen cyanide and impurities including nitrogen oxides and\\/or oxygen. The process comprises passing the gas over a sulphur-resistant hydrogenation catalyst at a temperature of from 120 to 250\\/sup degrees\\/ C and at a pressure of

A. D. Engelbrecht; G. J. Houten

1982-01-01

256

Mutation spectra of complex environmental mixtures  

SciTech Connect

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

DeMarini, D.M. [EPA, Research Triangle Park, NC (United States)

1997-10-01

257

Environmental research brief: Complex mixtures and ground water quality. Report for October 1991October 1992  

Microsoft Academic Search

The occurrence of organic chemicals in soil and groundwater has become an issue of great interest and import. Concomitantly, research on the transport and fate of organic contaminants in subsurface environments has expanded greatly in recent years. However, the behavior of 'complex mixtures' is beginning to receive increased attention. Examples of pertinent problems involving complex mixtures include the transport of

Brusseau

1993-01-01

258

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.

Mauderly, J L

1993-01-01

259

Pervaporation of dilute alcoholic mixtures using PDMS membrane  

Microsoft Academic Search

Pervaporation (PV) of methanol\\/water and ethanol\\/water mixtures through PDMS membrane was investigated using a PV cell (in laboratory scale). PDMS membrane is a well-known hydrophobic membrane for removing organics from aqueous mixtures. Experimental results were obtained at different initial alcohol (methanol and ethanol) concentrations (0.3–3wt%) and temperatures (30–50?C). Recirculation flow rate was kept constant at a value of 15.6l\\/h. Average

Toraj Mohammadi; Abdolreza Aroujalian; Ali Bakhshi

2005-01-01

260

Choice of basis mixtures for the prediction of vapor-liquid equilibria using the UNIFAC model  

SciTech Connect

A link was established between the accurate prediction of vapor-liquid equilibria and azeotropes using the UNIFAC group model and the choice of the basis information. The component activity coefficients are plotted as functions of composition for all the sets of data in each binary system. The activity coefficients at infinite dilution are determined as graphical extrapolations of these plots. The plot for the butanol-hydrocarbon system is shown. It is shown that azeotrope parameters can be used as the basis information to predict vapor-liquid equilibria for several sets of systems.

Kushner, T.M.; Fainburg, G.D.; Vitman, T.A.; Serafimov, L.A.

1988-07-01

261

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

262

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

263

Development of more efficacious Tc-99, organ imaging agents for use in nuclear medicine by analytical characterization of radiopharmaceutical mixtures: Progress report for period September 1, 1987-August 31, 1988  

SciTech Connect

The long-range objective of this research is the development of more efficacious technetium-99m radiopharmaceuticals for use as imaging agents in diagnostic nuclear medicine. These objectives are being met by the development of analytical techniques which are capable of separating radiopharmaceutical mixtures into their component technetium complexes for subsequent evaluation. Three areas have been investigated during the second year of this project. (1) A chromatographic procedure has been developed for the separation of technetium dicarboxypropane diphosphonate (DPD) complexes. Tc-DPD complexes have been isolated from radiopharmaceutical preparations. The concentration of each complex in the preparation varies significantly depending on the pH of the preparation, the concentration of technetium, the presence or absence of oxygen, and the time interval after preparation. A single Tc-DPD complex has been isolated which shows good skeletal uptake and rapid soft tissue clearance. (2) An HPLC procedure for analyzing urine for Tc-Diphosphonate complexes has been developed. A Tc-HEDP complexd injected into a dog was found to concentrate rapidly in the bladder in the same chemical form. (3) An HPLC technique for the determination of /sup 99m/TcO/sub 4//sup -/ in disphosphonate radiopharmaceuticals and biological samples has been developed. 15 refs., 2 figs.

Heineman, W.R.

1988-04-01

264

Development of more efficacious Tc-99m organ imaging agents for use in nuclear medicine by analytical characterization of radiopharmaceutical mixtures. Progress report, May 1, 1982-April 30, 1983  

SciTech Connect

A procedure based on high performance liquid chromatography (HPLC) has been developed for separating individual Tc-diphosphonate complexes in skeletal-imaging radiopharmaceuticals prepared by reduction of TcO/sub 4//sup -/ with NaBH/sub 4/ in the presence of methylene diphosphonate (MDP). Seven different Tc-MDP complexes have been detected and isolated in pure form. Significant differences in skeletal uptake and blood clearance are exhibited by the three complexes tested thus far by biodistribution studies in test animals. The relative quantities of these complexes present in a radiopharmaceutical preparation are dramatically influenced by the pH of the reaction mixture. Thus, control of pH is a simple means of forming in high yield the single, most efficacious Tc-MDP complex for skeletal imaginG. An HPLC method with electrochemical detection has been developed for the analytical determination of total TcO/sub 4//sup -/ (/sup 99m/Tc + /sup 99/Tc). Concentrations of TcO/sub 4//sup -/ as low as 9 x 10/sup -9/ M can be detected. The method is being evaluated for monitoring total TcO/sub 4//sup -/ in /sup 99/Mo//sup 99m/Tc generators.

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

1982-11-01

265

Development of more efficacious /sup 99m/Tc organ imaging agents for use in nuclear medicine by analytical characterization of radiopharmaceutical mixtures. Progress report, May 1, 1983-January 1, 1986  

SciTech Connect

The formation of many different technetium complexes in the Tc(NaBH4)-HEDP, Tc(NaBH4)-MDP, and Tc(NaBH4)-DMAD systems has been clearly demonstrated by HPLC-separation of reaction mixtures. The dramatically different biodistributions exhibited by the various complexes strongly suggests that an improved skeletal radiopharmaceutical would result if the single technetium complex which exhibits the optimum biodistribution properties is administered to the patient. The influence of pH, time, concentrations of TcO4 and ligand, and the nature of reductant on the relative amounts of the different complexes formed were investigated. Electrochemical reduction offers a means of possibly generating a desired complex in very high yield due to the precision with which redox potential can be controlled. Additionally, we have developed HPLC methods with uv and electrochemical detection for the determination of total TcO4 in eluents from the ZZMo//sup 99m/Tc radionuclide generator. The inadequacy of current theory to accurately predict total TcO4 in generator eluents was demonstrated in that the concentration of total TcO4 is a major factor determining the yield of individual Tc-diphosphonate complexes. Spectroelectrochemistry proved an effective technique to study the redox properties of Tc-complexes. 18 refs., 10 figs., 1 tab.

Heineman, W.R.

1986-01-01

266

Development of more efficacious Tc-99m organ imaging agents for use in nuclear medicine by analytical characterization of radiopharmaceutical mixtures: Progress report for period September 1, 1986-August 31, 1987  

SciTech Connect

The long-range objective of this research is the development of more efficacious technetium-99m radiopharmaceuticals for use as imaging agents in diagnostic nuclear medicine. The author developed analytical techniques that are capable of separating radiopharmaceutical mixtures into their component technetium complexes for subsequent evaluation. During this one-year period, a chromatographic procedure has been developed for the separation of technetium phosphonoacetic acid (PAA) complexes and five Tc-PAA complexes have been isolated from radiopharmaceutical preparations. The concentration of each complex in the preparation varies significantly depending on the pH of the preparation. Radiopharmaceutical preparations based on the ligand methylene diphosphonate (MDP) have been prepared by electrochemical reduction of TcO/sub 4//sup -/. The yields of different Tc-MDP complexes are affected by the potential applied to the electrochemical cell. The control of both potential and pH enables a specific Tc-MDP complex to be produced in purer form and higher yield than by chemical reduction. An EXAFS spectrum of a solution of chromatographically isolated Tc-HEDP (hydroxyethylidine diphosphonate) complex shows evidence for a Tc-Tc bond, which is supportive of the postulated oligomeric/polymeric nature of these complexes. 9 refs., 4 figs.

Heineman, W.R.

1987-06-01

267

Part 2: Limiting apparent molar volume of organic and inorganic 1:1 electrolytes in (water + ethylammonium nitrate) mixtures at 298 K – Thermodynamic approach using Bahe–Varela pseudo-lattice theory  

Microsoft Academic Search

Values of partial molar volumes at infinite dilution of 9 inorganic and 4 organic 1:1 electrolytes have been determined in (water+ethylammonium nitrate) (EAN) binary at 298.15K throughout the composition scale. Our theoretical analysis shows that the values of partial molar volumes at infinite dilution of a solute in a binary are linked to those of the partial molar volumes of

Sabbah Bouguerra; Ibrahim Bou Malham; Pierre Letellier; Alain Mayaffre; Mireille Turmine

2008-01-01

268

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

SciTech Connect

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

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

1980-12-01

269

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.

270

RISK ASSESSMENT OF COMPLEX MIXTURES  

EPA Science Inventory

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

271

Understanding Anthropogenic and Biogenic Primary and Secondary Aerosol Mixtures  

NASA Astrophysics Data System (ADS)

Atmospheric organic matter can constitute 20-70% of the total fine aerosol mass, yet much of its chemical composition is not well understood nor are the mechanisms via which these compounds form. Continental organic aerosol can be directly emitted as primary aerosol from combustion sources or formed in the atmosphere via secondary process with both biogenic and anthropogenic hydrocarbon precursors. In urban air masses, the mixture of anthropogenic primary emissions and secondary organic aerosol (SOA) is ubiquitous. Changes due to the mixing of the different organic chemical compositions can affect the oxidation state and ageing properties of particulates. Hence the change in state can consequently impact air quality, public health and regional climate. The mixing state and the affinity of primary emissions with SOA not well understood: very little is known about the properties of these mixtures. In this a study, SOA formed in the Carnegie Mellon University environmental smog chamber is mixed with diesel exhaust and motor oil aerosol. The objective is to combine two aerosol classes in an external mixture and to then watch the dynamics as well as total mass balance as the mixtures come to equilibrium, possibly forming a single, internal mixture. The SOA is formed from monoterpene and sesquiterpene precursors, specifically ?-pinene and ?- caryophyllene SOA formed via dark ozonlysis. Primary aerosol is injected into the chamber once the biogenic nucleation and growth has completed and the mixture is allowed to age for three to four hours. A suite of instruments characterize the changes in size, volatility, and chemical composition of the aerosol mixtures. Scanning Mobility Particle Sizers record changes in the size distribution before and after mixing. An Aerodyne High Resolution Time of Flight Aerosol Mass Spectrometer measures the change in mass spectra and the composition of separate size modes both before and after the mixing event, and a thermodenuder is used to characterize changes in mixed aerosol volatility.

Asa-Awuku, A.; Miracola, M.; Lee, B. D.; Kroll, J.; Pandis, S.; Robinson, A.; Donahue, N.

2008-12-01

272

Latent classiness and other mixtures.  

PubMed

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

Neale, Michael C

2014-05-01

273

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

274

Concentration fluctuations and collective properties in mixed liquid systems: Rayleigh-Brillouin spectra of tert-butyl alcohol/ 2,2'-dimethylbutane liquid mixture  

NASA Astrophysics Data System (ADS)

Rayleigh-Brillouin spectra have been measured in a range of temperatures and compositions of t-butyl alcohol/2,2'-dimethylbutane liquid mixture. The mixture mole fraction has been varied from pure alkane (xTBA=0) to pure alcohol (xTBA=1) at temperatures between 283 and 323 K. In the same composition and temperature ranges the authors also executed measurements of mass density, shear viscosity, and refractive index. From light scattering spectra the authors have extracted the hypersound velocities and adiabatic compressibilities and evaluated their excess values. Moreover, the authors attempted to evaluate the isothermal (40 °C) Landau-Placzek ratios at various mole fractions, but these values proved to be subject to significant errors due to great uncertainty in the central component intensity measurements. Thus, in discussing the results, this latter quantity was considered only from a qualitative point of view. These results highlight a nonideal behavior of the studied liquid mixture with a probable azeotropic composition around xTBA=0.7 due to formation of small clusters of hydrogen-bonded alcohol tetramers that are completely surrounded by solvent molecules and analogous or smaller clusters. These clusters, shaped as inverse micelles, offer their hydrophobic moiety towards the molecules that constitute the solvation shell, resulting in a low polarity solution structure that minimizes the solute-solvent interactions. Differences in thermal and compositional behavior of excess molar volumes and adiabatic compressibilities have been interpreted by attributing different weights to the solute-solvent interaction forces and to the hydrogen bond connectivity effects.

Cataliotti, Rosario Sergio; Palombo, Francesca; Paolantoni, Marco; Sassi, Poala; Raudino, Antonio

2007-01-01

275

Concentration fluctuations and collective properties in mixed liquid systems: Rayleigh-Brillouin spectra of tert-butyl alcohol/2,2'-dimethylbutane liquid mixture.  

PubMed

Rayleigh-Brillouin spectra have been measured in a range of temperatures and compositions of t-butyl alcohol/2,2(')-dimethylbutane liquid mixture. The mixture mole fraction has been varied from pure alkane (x(TBA)=0) to pure alcohol (x(TBA)=1) at temperatures between 283 and 323 K. In the same composition and temperature ranges the authors also executed measurements of mass density, shear viscosity, and refractive index. From light scattering spectra the authors have extracted the hypersound velocities and adiabatic compressibilities and evaluated their excess values. Moreover, the authors attempted to evaluate the isothermal (40 degrees C) Landau-Placzek ratios at various mole fractions, but these values proved to be subject to significant errors due to great uncertainty in the central component intensity measurements. Thus, in discussing the results, this latter quantity was considered only from a qualitative point of view. These results highlight a nonideal behavior of the studied liquid mixture with a probable azeotropic composition around x(TBA)=0.7 due to formation of small clusters of hydrogen-bonded alcohol tetramers that are completely surrounded by solvent molecules and analogous or smaller clusters. These clusters, shaped as inverse micelles, offer their hydrophobic moiety towards the molecules that constitute the solvation shell, resulting in a low polarity solution structure that minimizes the solute-solvent interactions. Differences in thermal and compositional behavior of excess molar volumes and adiabatic compressibilities have been interpreted by attributing different weights to the solute-solvent interaction forces and to the hydrogen bond connectivity effects. PMID:17286485

Cataliotti, Rosario Sergio; Palombo, Francesca; Paolantoni, Marco; Sassi, Poala; Raudino, Antonio

2007-01-28

276

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

Microsoft Academic Search

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

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

1999-01-01

277

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

278

Bridging environmental mixtures and toxic effects.  

PubMed

Biological Response Indicator Devices Gauging Environmental Stressors (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, OR, USA. Six sampling events were conducted in the summer and fall of 2009 and 2010. Passive sampling device extracts were analyzed for polycyclic aromatic hydrocarbon (PAH) compounds and screened for 1,201 chemicals of concern using deconvolution-reporting software. The developmental toxicity of the extracts was analyzed using the embryonic zebrafish bioassay. The BRIDGES tool 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 elucidated spatial and temporal trends in 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 the present study 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

2012-12-01

279

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.

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

2012-01-01

280

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

281

Complex mixtures: Hazard identification and risk assessment  

Microsoft Academic Search

Regarding risk evaluation of complex mixtures, the Working Group discussed the following topics: evaluation of the mixture as a whole, fractionation of the mixture, identification of the ‘top ten’ chemicals, and composite standards. It was concluded that no standard methodology for hazard identification and risk assessment of complex mixtures yet exists, but assessment of complex mixtures must proceed, using all

R. M. Fay; V. J. Feron

1996-01-01

282

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

283

TEA laser gas mixture optimization  

SciTech Connect

The topographical plot of an optimized parameter, such as pulse energy or peak power, on the gas mixture plane is presented as a useful aid in realizing optimum mixtures of helium, carbon dioxide, and nitrogen, for operation of CO/sub 2/ TEA lasers. A method for generating such a plot is discussed and an example is shown. The potential benefits of this graphical technique are also discussed.

Lipchak, W.M.; Luck, C.F.

1982-11-01

284

Evaluation of Superpave Mixtures Containing Hydrated Lime.  

National Technical Information Service (NTIS)

The use of hydrated lime in Hot-Mix Asphalt (HMA) mixtures can reduce permanent deformation, long-term aging, and moisture susceptibility of mixtures. In addition, hydrated lime increases the stiffness and fatigue resistance of mixtures. This study evalua...

A. Raghavendra L. N. Mohammad S. Cooper S. Kabir

2013-01-01

285

40 CFR 721.9540 - Polysulfide mixture.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Polysulfide mixture. 721.9540 Section 721...Chemical Substances § 721.9540 Polysulfide mixture. (a) Chemical substance...substance identified generically as a polysulfide mixture (PMN P-93-1043)...

2010-07-01

286

40 CFR 721.9540 - Polysulfide mixture.  

Code of Federal Regulations, 2010 CFR

...2009-07-01 2009-07-01 false Polysulfide mixture. 721.9540 Section 721...Chemical Substances § 721.9540 Polysulfide mixture. (a) Chemical substance...substance identified generically as a polysulfide mixture (PMN P-93-1043)...

2009-07-01

287

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

288

Nonlocal viscosity kernel of mixtures.  

PubMed

In this Brief Report we investigate the multiscale hydrodynamical response of a liquid as a function of mixture composition. This is done via a series of molecular dynamics simulations in which the wave-vector-dependent viscosity kernel is computed for three mixtures, each with 7-15 different compositions. We observe that the viscosity kernel is dependent on composition for simple atomic mixtures for all the wave vectors studied here; however, for a molecular mixture the kernel is independent of composition for large wave vectors. The deviation from ideal mixing is also studied. Here it is shown that the Lorentz-Berthelot interaction rule follows ideal mixing surprisingly well for a large range of wave vectors, whereas for both the Kob-Andersen and molecular mixtures large deviations are found. Furthermore, for the molecular system the deviation is wave-vector dependent such that there exists a characteristic correlation length scale at which the ideal mixing goes from underestimating to overestimating the viscosity. PMID:22463265

Smith, Ben; Hansen, J S; Todd, B D

2012-02-01

289

Combining Mixture Components for Clustering*  

PubMed Central

Model-based clustering consists of fitting a mixture model to data and identifying each cluster with one of its components. Multivariate normal distributions are typically used. The number of clusters is usually determined from the data, often using BIC. In practice, however, individual clusters can be poorly fitted by Gaussian distributions, and in that case model-based clustering tends to represent one non-Gaussian cluster by a mixture of two or more Gaussian distributions. If the number of mixture components is interpreted as the number of clusters, this can lead to overestimation of the number of clusters. This is because BIC selects the number of mixture components needed to provide a good approximation to the density, rather than the number of clusters as such. We propose first selecting the total number of Gaussian mixture components, K, using BIC and then combining them hierarchically according to an entropy criterion. This yields a unique soft clustering for each number of clusters less than or equal to K. These clusterings can be compared on substantive grounds, and we also describe an automatic way of selecting the number of clusters via a piecewise linear regression fit to the rescaled entropy plot. We illustrate the method with simulated data and a flow cytometry dataset. Supplemental Materials are available on the journal Web site and described at the end of the paper.

Baudry, Jean-Patrick; Raftery, Adrian E.; Celeux, Gilles; Lo, Kenneth; Gottardo, Raphael

2010-01-01

290

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

291

Bayesian Kernel Mixtures for Counts  

PubMed Central

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.

Canale, Antonio; Dunson, David B.

2011-01-01

292

PREDICTION OF MULTICOMPONENT ADSORPTION EQUILIBRIA IN BACKGROUND MIXTURES OF UNKNOWN COMPOSITION  

EPA Science Inventory

A technique has been developed to predict the adsorption equilibria of known organic solutes onto granular activated carbon (GAC) in mixtures of unknown composition. Ideal adsorbed solution theory (IAST) was used to describe the competitive interactions between adsorbates. Theore...

293

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...

294

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

2011-01-04

295

Prediction of Multicomponent Adsorption Equilibria in Background Mixtures of Unknown Composition.  

National Technical Information Service (NTIS)

A technique has been developed to predict the adsorption equilibria of known organic solutes onto granular activated carbon (GAC) in mixtures of unknown composition. Ideal adsorbed solution theory (IAST) was used to describe the competitive interactions b...

J. C. Crittenden P. Luft D. W. Hand

1985-01-01

296

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

297

The ageing of bordeaux mixture  

Microsoft Academic Search

Summary  Bordeaux mixture (5:5:50) prepared at room temperature (24°C.) contains a high initial concentration of copper in the aqueous\\u000a phase (4 to 7 mg. copper\\/litre). On keeping the mixture at 24°C. the copper content of the solution decreases, and in a few\\u000a days, attains a steady value of 0·47 mg. copper per litre.\\u000a \\u000a The changes in copper concentration of the aqueous

G. Narayan; B. Sanjiva Rao

1951-01-01

298

Gaussian-mixture umbrella sampling  

PubMed Central

We introduce the Gaussian-mixture umbrella sampling method (GAMUS), a biased molecular dynamics technique based on adaptive umbrella sampling that efficiently escapes free energy minima in multi-dimensional problems. The prior simulation data are reweighted with a maximum likelihood formulation, and the new approximate probability density is fit to a Gaussian-mixture model, augmented by information about the unsampled areas. The method can be used to identify free energy minima in multi-dimensional reaction coordinates. To illustrate GAMUS, we apply it to the alanine dipeptide (2D reaction coordinate) and tripeptide (4D reaction coordinate).

van der Vaart, Arjan; Karplus, Martin

2009-01-01

299

Self-Organizing Hidden Markov Models  

Microsoft Academic Search

\\u000a The self-organizing mixture models (SOMMs) were proposed as an expectation-maximization (EM) algorithm that yields topology\\u000a preserving maps of data based on probabilistic mixture models. Compared to self-organizing maps, the SOMM algorithm has a\\u000a clear interpretation: it maximizes the sum of data log likelihood and a penalty term that enforces self-organization. The\\u000a object of this paper is to extend the SOMM

Nobuhiko Yamaguchi

2010-01-01

300

Charge transfer and doping at organic/organic interfaces  

NASA Astrophysics Data System (ADS)

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

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

2003-11-01

301

FBST for Mixture Model Selection  

NASA Astrophysics Data System (ADS)

The Fully Bayesian Significance Test (FBST) is a coherent Bayesian significance test for sharp hypotheses. This paper proposes the FBST as a model selection tool for general mixture models, and compares its performance with Mclust, a model-based clustering software. The FBST robust performance strongly encourages further developments and investigations.

Lauretto, Marcelo S.; Stern, Julio M.

2005-11-01

302

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

303

Education: The Mixture as Before  

ERIC Educational Resources Information Center

"The Northian", a Canadian magazine for teachers in Indian, Eskimo and northern schools, was located in the University of Saskatchewan, Saskatoon. The article "Education: The Mixture as Before" was an examination of the educational trends across Canada in the wake of the Hall-Denis Report. The article sought to confront the educational…

Paskell, Anthony

1969-01-01

304

DIELECTRIC PROPERTIES OF TERPHENYL MIXTURES  

Microsoft Academic Search

The electrical properties of a mixture of terphenyls were measured. The ; data for dielectric constant at 1, 10. and 100 kc are summarized as a function of ; temperature over the range 375 to 675 deg F. The dipole moments of the terphenyl ; isomers are shown to be approximately zero and the induced polarizability is ; shown to

R. J. Sullivan; F. C. Silvey

1960-01-01

305

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

306

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...

307

Occupational neurotoxicology of organic solvents and solvent mixtures  

Microsoft Academic Search

The results of two field studies in painters and spray painters, the outcomes of examinations of workers with suspected work-related disease due to solvents, as well as data from an evaluation of an epidemiologic study in painters with confirmed occupational disease, are presented and discussed. The results of these studies and the experiences in occupational medicine in the Federal Republic

G TRIEBIG

1989-01-01

308

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).

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

2002-01-01

309

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

310

Purification of metal-organic framework materials  

DOEpatents

A method of purification of a solid mixture of a metal-organic framework (MOF) material and an unwanted second material by disposing the solid mixture in a liquid separation medium having a density that lies between those of the wanted MOF material and the unwanted material, whereby the solid mixture separates by density differences into a fraction of wanted MOF material and another fraction of unwanted material.

Farha, Omar K.; Hupp, Joseph T.

2012-12-04

311

Oxide mixtures for UV coatings  

NASA Astrophysics Data System (ADS)

In the past decades, efforts have been concentrated on reaching more laser resistant multilayers optical components in the Infrared (IR) range. New designs and materials have been investigated and among them binary or ternary oxide mixtures have revealed to be very profitable to improve the laser damage resistance of the coatings in the IR. The physical characteristics of such mixed materials are indeed tunable and the deposition process associated allows to obtain multilayers with smoother interfaces, which reduces considerably the damage threshold of the component. The present work is focused on the study of pure materials and their binary oxide mixtures in the UV range, using S-on-1 testing, for two different laser beam sizes. Samples resistance to multipulse irradiation is then compared for both beam sizes, extracting the data with a thermal model assuming nanometric inclusions. The fatigue effects of the set of sample have also been investigated, showing no clear trend of fatigue for all tested components.

Gouldieff, Céline; Wagner, Frank; Jensen, Lars; Mende, Mathias; Natoli, Jean-Yves; Ristau, Detlev

2012-11-01

312

Effective permittivity of dielectric mixtures  

NASA Technical Reports Server (NTRS)

General mixing formulas are derived for discrete scatterers immersed in a host medium. The inclusion particles are assumed to be ellipsoidal. The electric field inside the scatterers is determined by quasi-static analysis, assuming the diameter of the inclusion particles to be much smaller than one wavelength. The results are applicable to general multiphase mixtures, and the scattering ellipsoids of the different phases can have different sizes and arbitrary ellipticity distribution and axis orientation, i.e., the mixture may be isotropic or anisotropic. The resulting mixing formula is nonlinear and is suitable for iterative solutions. The formula contains a quantity called the apparent permittivity, and with different choices of this quantity, the result leads to the generalized Lorentz-Lorenz formula, the generalized Polder-van Santen formula, and the generalized coherent potential-quasicrystalline approximation formula. The results are applied to calculating the complex effective permittivity of dry and wet snow, and sea ice.

Sihvola, Ari H.; Kong, Jin AU

1988-01-01

313

Entanglement rules for random mixtures.  

PubMed

We discuss how two subparts of a randomly stirred scalar mixture interact to form the overall concentration distribution. We derive, in particular, the appropriate composition laws in the absence and presence of a strong correlation between the fields. The resulting concentration distributions compare favorably with several distinct experiments, illustrating the two limits. The initial relative spatial position of the subparts plays a crucial role on the nature of their subsequent entanglement. PMID:20867769

Duplat, J; Jouary, A; Villermaux, E

2010-07-16

314

High Pressure Thermodynamics of Mixtures  

Microsoft Academic Search

Abstract—In the present survey some important trends in the high pressure thermodynamics,of fluid mixtures of non-electrolytesare reviewed. First the pressure dependence,of excess functions such as the excess Gibbs energy GE, the excess enthalpy HE, the excess entropy SE and the excess heat capacity CE is discussed. It can be obtained from the knowledge,of the excess volume a function of pressure

G. M. Schneider

1976-01-01

315

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

316

Perfluoroolefin and perfluoroparaffin mixture and process for making same  

SciTech Connect

Straight chain perfluoroolefins compounds of medium length with terminal or double bonds and a minor proportion of trifluoromethyl side chains or mixtures of such perfluoroolefins with perfluoro paraffins of equal chain length and corresponding structure, the perfluoroolefins being present in the mixture in an amount of 40 to 70% are prepared. The compounds are valuable as highly reactive intermediate products in the production of surface active agents. The compounds are made by subjecting a highly fluorinated organic compound to degradation by means of a high energy radiation of a density of 0.3 to 3.0 w/cm2 effected in a radiation chamber which has been subjected to a preceding rinsing with an inert gas or with a monomeric highly fluorinated organic compound.

Dietrich, P.; Engler, G.; Ferse, A.; Grimm, H.; Gross, U.; Handte, D.; Lunkwitz, K.; Muller, U.; Prescher, D.; Schulze, J.

1980-09-30

317

Model Misspecification: Finite Mixture or Homogeneous?  

PubMed

A common problem in statistical modelling is to distinguish between finite mixture distribution and a homogeneous non-mixture distribution. Finite mixture models are widely used in practice and often mixtures of normal densities are indistinguishable from homogenous non-normal densities. This paper illustrates what happens when the EM algorithm for normal mixtures is applied to a distribution that is a homogeneous non-mixture distribution. In particular, a population-based EM algorithm for finite mixtures is introduced and applied directly to density functions instead of sample data. The population-based EM algorithm is used to find finite mixture approximations to common homogeneous distributions. An example regarding the nature of a placebo response in drug treated depressed subjects is used to illustrate ideas. PMID:18974843

Tarpey, Thaddeus; Yun, Dong; Petkova, Eva

2008-01-01

318

Water Solubility Behavior of Binary Hydrocarbon Mixtures.  

National Technical Information Service (NTIS)

The aqueous solubility equilibrium behavior of seven medium molecular weight, liquid, binary hydrocarbon mixtures has been determined at 20 C. Binary hydrocarbon mixtures containing structurally similar compounds exhibited ideal solution behavior, but dev...

D. R. Burris W. G. MacIntyre

1985-01-01

319

Treatability of Textile-Domestic Waste Mixtures.  

National Technical Information Service (NTIS)

Qualitative and quantitative treatability information was obtained on highly alkaline mixtures of textile and domestic waste without pH adjustment. Mixture ratios, detention time, rate of solids recycle, and temperature effects were investigated. The kine...

J. F. Judkins

1975-01-01

320

Temperature Rise of Mass Concrete Mixtures.  

National Technical Information Service (NTIS)

Temperature rise of 11 mixtures, six containing varying large amounts of pozzolan and small amounts of portland cement with chemical admixtures, was investigated. All concrete mixtures contained manufactured limestone fine aggregate and 6-in. maximum size...

W. O. Tynes

1968-01-01

321

Polymerized Crumb Rubber Modified Mixtures in Minnesota.  

National Technical Information Service (NTIS)

The objectives of the research program were to: (1) Define asphalt-rubber interactions; (2) Conduct a preliminary assessment of both laboratory tests and the resulting mixture properties of crumb rubber modified bituminous (CRM) mixtures; (3) Evaluate bot...

D. E. Newcomb M. Stroup-Gardiner J. R. Kim B. Allen J. Wattenhoffer-Spry

1994-01-01

322

Phase equilibria for complex fluid mixtures  

Microsoft Academic Search

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

J. M. Prausnitz

1983-01-01

323

21 CFR 82.6 - Certifiable mixtures.  

...mixture; (2) Each diluent in such batch of mixture is harmless and suitable for use therein; and (3) No diluent (except resins, natural gum, pectin and, in the case of mixtures which are aqueous solutions or aqueous pastes, sodium benzoate in a...

2014-04-01

324

Human Tracking with Mixtures of Trees  

Microsoft Academic Search

Tree-structured probabilistic models admit simple, fast in- ference. However, they are not well suited to phenomena such as occlusion, where multiple components of an object may disappear simultaneously. Mixtures of trees appear to address this problem, at the cost of representing a large mixture. We demonstrate an efficient and compact repre- sentation of this mixture, which admits simple learning and

Sergey Ioffe; David A. Forsyth

2001-01-01

325

Paraffin wax mixtures as phase change materials  

Microsoft Academic Search

Melting of the binary mixture system of tetradecane and hexadecane in Differential Scanning Calorimetry (DSC) cell has been investigated experimentally and numerically. Different concentrations of tetradecane–hexadecane paraffin mixture were studied. It is found that the phase change process of the binary mixture takes place over a temperature range and the temperature range depends on both the heating rate and the

T. Kousksou; A. Jamil; T. El Rhafiki; Y. Zeraouli

2010-01-01

326

Means for Burning Fuel-Air Mixtures.  

National Technical Information Service (NTIS)

Means are known for burning fuel-air mixtures in a dual-cavity combustion chamber of an internal combustion engine with external mixture formation by feeding the mixture from the primary chamber into a secondary chamber through a connecting passage and ig...

M. F. Chepovskii

1974-01-01

327

Explosive Mixtures Detonating at Low Velocity  

Microsoft Academic Search

Summary Same explosive mixtures detonating at a low velocity and not containing high explosives were experimentally investigated. As a system providing detonation capability, a mixture of ammonium nitrate and powdered aluminium was employed. Glass or urea-form- aldehyde resin beads or lead oxides were used to reduce detonation parameters. Detonation velocity and critical diameter were measured for mixtures differentiated in composition

Andrzej Maranda; Stanis?aw Cudzi?o

2001-01-01

328

Six interaction profiles for simple mixtures  

Microsoft Academic Search

The Agency for Toxic Substances and Disease Registry (ATSDR) has a program for chemical mixtures that encompasses research on chemical mixtures toxicity, health risk assessment, and development of innovative computational methods. ATSDR prepared a guidance document that instructs users on how to conduct health risk assessment on chemical mixtures (Guidance Manual for the Assessment of Joint Toxic Action of Chemical

Hana R Pohl; Nickolette Roney; Sharon Wilbur; Hugh Hansen; Christopher T De Rosa

2003-01-01

329

Deliquescence properties of mixed organic aerosols  

NASA Astrophysics Data System (ADS)

The water soluble organic component of the tropospheric aerosol consists of a complex mixture comprising mono- and di-acids, polyols, dialkyl ketones, polyphenols and polycarboxylic acids. Its impact on the light scattering, hygroscopicity, and phase transitions is of prime interest to determine the aerosol’s cloud forming and climatic properties. By now, only a minor part of the organic mass can be resolved into specific molecular compounds. A number of laboratory studies have investigated the influence of the organic fraction on aerosol properties often using one dicarboxylic acid as a representative model compound. Up to know, little attention was paid to the fact that the organics constitute a mixture. In contrast, in this study the organic fraction is represented by a mixture of dicarboxylic acids. Saturated aqueous solutions have been prepared in an iterative procedure: small portions of material were added until the solution was saturated with respect to each component. The water activity of these eutonic compositions has been determined revealing the following trend: the deliquescence relative humidity decreases continuously with increasing number of components. This result is viewed as a general trend that holds for the whole water soluble organic fraction. Therefore, one can conclude that a liquid solution as the stable physical state becomes increasingly favored the more components the mixture contains. In a second step, inorganic salts were added to the organic mixture. The aqueous solubility and deliquescence properties of these mixtures were investigated.

Marcolli, C.

2003-04-01

330

Modelling of water\\/organic vapor dehydration by glassy polymer membranes  

Microsoft Academic Search

Hydrophilic glassy polymers are suitable membranes for the dehydration of water\\/organic vapor mixtures. Vapor permeation is the predominant process for the dehydration of organic vapors employing glassy polymers. The permeation of vapor mixtures through this type of membrane is usually analyzed in terms of a dual-mode transport model which fails to predict well the separation behavior of a vapor mixture.

A. Salem; A. A. Ghoreyshi

2006-01-01

331

High Efficiency Organic Photovoltaic Cells Employing Hybridized Mixed Planar Heterojunctions.  

National Technical Information Service (NTIS)

A device is provided, having a first electrode, a second electrode, and a photoactive region disposed between the first electrode and the second electrode. The photoactive region includes a first organic layer comprising a mixture of an organic acceptor m...

B. P. Rand J. Xue S. Forrest S. Uchida

2004-01-01

332

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.

Cowin, Stephen C.; Cardoso, Luis

2011-01-01

333

The single substance and mixture toxicity of quinolones to the bioluminescent bacterium Vibrio fischeri  

Microsoft Academic Search

Quinolones are one of the most important group of synthetic antibiotics used in aquaculture. We studied the single substance and mixture toxicity of ten quinolones using a long term bioluminescence inhibition assay with the marine bacterium Vibrio fischeri as the test organism. All tested quinolones are highly toxic to the test organism with EC50 values ranging from 14 ?g\\/l for

T. Backhaus; M. Scholze; L. H. Grimme

2000-01-01

334

Degradation of mixtures of phenols using boron doped diamond electrodes for wastewater treatment  

Microsoft Academic Search

A model is proposed for describing the electrochemical oxidation of multicomponent mixtures of organic compounds, when significant mineralization (i.e., combustion to CO2) of the compounds occurs. This is known to be the case of the degradation of many organic compounds on boron doped diamond (BDD) and other new electrocatalytic materials used as anodes. The proposed model predicts the variation of

A. Morão; A. Lopes; M. T. Pessoa de Amorim; I. C. Gonçalves

2004-01-01

335

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

336

BBC Bitesize: Compounds and Mixtures  

NSDL National Science Digital Library

This animated tutorial for grades 6-9, published by the British Broadcasting Corporation, explores the molecular basis of compounds and mixtures. It is written in "bite-size" pieces so that adolescent learners can grasp the concepts more easily and connect information with prior knowledge. Each page is supplemented with audio narration and illustrations. Learners will try to fuse or separate elements, giving them insight into the bonding process without introducing advanced vocabulary. They will also view animations of filtration and evaporation. The tutorial ends with a brief quiz that allows students to self-test their understanding.

Bitesize, General C.

2011-06-27

337

Generating mixtures of spatial qubits  

NASA Astrophysics Data System (ADS)

In a recent letter [L. Neves, G. Lima, J.G. Aguirre Gómez, C.H. Monken, C. Saavedra, S. Pádua, Phys. Rev. Lett. 94 (2005) 100501], we presented a scheme for generating pure entangled states of spatial qudits ( D-dimensional quantum systems) by using the momentum transverse correlation of the parametric down-converted photons. In this work, we discuss a generalization of this process to enable the creation of mixed states. With the technique proposed we experimentally generated a mixture of two spatial qubits.

Lima, G.; Torres-Ruiz, F. A.; Neves, Leonardo; Delgado, A.; Saavedra, C.; Pádua, S.

2008-10-01

338

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

339

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) [Richland, WA; Lilga, Michael A. (Richland, WA) [Richland, WA

1998-01-01

340

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

341

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

342

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

343

Modeling biofiltration of VOC mixtures under steady-state conditions  

SciTech Connect

Treatment of air streams contaminated with binary volatile organic compound (VOC) mixtures in classical biofilters under steady-state conditions of operation was described with a general mathematical model. The model accounts for potential kinetic interactions among the pollutants, effects of oxygen availability on biodegradation, and biomass diversification in the filter bed. While the effects of oxygen were always taken into account, two distinct cases were considered for the experimental model validation. The first involves kinetic interactions, but no biomass differentiation, used for describing data from biofiltration of benzene/toluene mixtures. The second case assumes that each pollutant is treated by a different type of biomass. Each biomass type is assumed to form separate patches of biofilm on the solid packing material, thus kinetic interference does not occur. This model was used for describing biofiltration of ethanol/butanol mixtures. Experiments were performed with classical biofilters packed with mixtures of peat moss and perlite (2:3, volume:volume). The model equations were solved through the use of computer codes based on the fourth-order Runge-Kutta technique for the gas-phase mass balances and the method of orthogonal collocation for the concentration profiles in the biofilms. Good agreement between model predictions and experimental data was found in almost all cases. Oxygen was found to be extremely important in the case of polar VOCs (ethanol/butanol).

Baltzis, B.C. [New Jersey Inst. of Tech., Newark, NJ (United States); Wojdyla, S.M. [Merck and Co., Inc., Rahway, NJ (United States); Zarook, S.M. [King Fahd Univ. of Petroleum and Minerals, Dhahran (Saudi Arabia). Dept. of Chemical Engineering

1997-06-01

344

Maximum supercoolign in liquid /sup 3/He-/sup 4/He mixtures near the tricritical point  

SciTech Connect

Measurements of supercooling in liquid /sup 3/He-/sup 4/He mixtures near the tricritical point are presented. The reduced temperature range 0.001 < epsilon identical to (1 - T/T/sub t/) < 0.01 was investigated for three different rates of cooling using a pressure-quench technique. For epsilon < 0.012, the maximum supercooling was found to be a function of the cooling rate. Comparisons with data in organic binary mixtures are given.

Sinha, D.N.; Hoffer, J.K.

1984-01-01

345

Isobaric vapor–liquid equilibrium for binary and ternary mixtures of 2-methyl-2-propanol+methyl 1,1-dimethylpropyl ether+2,2,4-trimethylpentane  

Microsoft Academic Search

New consistent vapor–liquid equilibrium (VLE) data for the binary system methyl 1,1-dimethylpropyl ether (TAME)+2,2,4-trimethylpentane (isooctane) and the ternary system 2-methyl-2-propanol (TBA)+methyl 1,1-dimethylpropyl ether (TAME)+2,2,4-trimethylpentane (isooctane) are reported at 101.3kPa. In the binary system, the results indicate a positive deviation from ideality and no azeotrope is present. The ternary system presents a saddle point azeotrope that can be predicted from binary

Sonia Loras; Antonio Aucejo; Rosa Muñoz; Javier de la Torre

2000-01-01

346

Symmetrical mixtures in external fields.  

PubMed

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

Materniak, S; Patrykiejew, A

2013-07-01

347

Secondary avalanches in gas mixtures  

NASA Astrophysics Data System (ADS)

Avalanche development in gas-based detectors relies not only on direct ionisation but also on excitation of noble gas atoms. Some quencher molecules can be ionised when they collide with excited atoms, a process on which we reported earlier [1]. Alternatively, excited atoms can decay by photon emission. If these photons are insufficiently absorbed by the quencher, yet capable of ionising, then they may escape from the avalanche region and start secondary avalanches. This process, called photon feedback, leads to an over-exponential increase of the gas gain which limits the working range. In this paper, we derive photon feedback parameters from published gain measurements for several gas mixtures and fit these parameters in a model which describes their dependence on the quencher concentration and the pressure.

?ahin, Özkan; Tapan, ?lhan; Veenhof, Rob

2013-08-01

348

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.

349

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

PubMed Central

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

Latino, Diogo A. R. S.; Aires-de-Sousa, Joao

2014-01-01

350

Thermal decomposition of acetic anhydride-nitric acid mixtures.  

PubMed

The adoption of Ac2O/HNO3 mixtures for the nitration of organics or the preparation of nitric esters is not free from some risks of explosion. The behaviour of these mixtures at varying Ac2O/HNO3 molar ratios is studied by means of adiabatic and scanning calorimetry. A simplified kinetic model, based on two lumped reactions (one of which leads to the formation of tetranitromethane) is developed to simulate the thermal decomposition of the investigated system under adiabatic conditions. The use of this model allows satisfactory prediction of the temperature profiles in the reactor whereas calculated pressures are generally overestimated due to some model inadequacies to account for the absorption of gaseous decomposition products into the reacting solution. PMID:11827716

Andreozzi, Roberto; Marotta, Raffaele; Sanchirico, Roberto

2002-03-01

351

Fuzzy Gaussian mixture models for speaker recognition  

Microsoft Academic Search

Abstract The Gaussian mixture model (GMM) is an important application of statistical clustering to speaker ,recognition. A number,of prototypes,are generated,from the training feature vectors by representing,the feature space as a mixture of Gaussian distributions. Each prototype consists of a model parameter set including mean vector, covariance matrix and mixture weight. In fuzzy clustering, the fuzzy c-means (FCM) method is the

Dat Tran; Tu Van Le; Michael Wagner

1998-01-01

352

Joule-Thomson cooling with binary mixtures  

NASA Astrophysics Data System (ADS)

The possibility of achieving temperatures below that of liquid nitrogen for applications in miniature one-shot Joule-Thomson (J-T) coolers using a mixture of nitrogen and neon gases is discussed. An expression for the maximum inversion temperature of binary mixtures is derived. It is shown that it is possible to achieve temperatures near the triple point of nitrogen (63 K) with a mixture of neon and nitrogen.

Sreedhar, R.; Sreedhar, A. K.

1998-12-01

353

Limit of miscibility and nanophase separation in associated mixtures.  

PubMed

We present a detailed analysis of the mixing process in an associating system, the water-tert-butanol (2-methyl-2-propanol) mixture. Using molecular dynamics simulations, together with neutron, X-ray diffraction experiments, and pulsed gradient spin-echo NMR, we study the local structure and dynamic properties over the full concentration range, and thereby provide quantitative data that reveal relationships between local structure and macroscopic behavior. For an alcohol-rich mixture, diffraction patterns from both neutron and X-ray experiments exhibit a peak at low wavelength vector (q ? 0.7 Å(-1)) characteristic of supermolecular structures. On increasing the water content, this "prepeak" progressively flattens and shifts to low wave vector . We identify hydrogen bonds in the system as the driving force for the specific organization that appears in mixtures, and provide an analysis of the variation of the cluster size distribution with composition. We find that the sizes of local hydrogen-bonded clusters observed in alcohol-rich mixtures become larger as the mole fraction, x(w), of water is increased; a nanophase separation is seen for x(w) in the range 0.6-0.7. This corresponds to several changes in some macroscopic properties of the liquid mixture. Thus, we propose a microscopic description of the effect of water addition in alcohol, which is in agreement with both neutron diffraction pattern and mobility of water and alcohol species. In summary we present a full and comprehensive description of miscibility at its limit in an associated system. PMID:23937163

Artola, P A; Raihane, A; Crauste-Thibierge, C; Merlet, D; Emo, M; Alba-Simionesco, C; Rousseau, B

2013-08-22

354

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

355

Acid digestion of organic liquids  

Microsoft Academic Search

Laboratory studies on the destruction of liquid organic wastes by acid digestion are discussed. A variety of liquid waste types was tested, including those encountered in the nuclear industry as well as some organic liquids representative of non-nuclear industrial wastes. The liquids tested were vacuum pump oil, tri-n-butyl phosphate (TBP), normal paraffin hydrocarbon solvent (NPH), a mixture of 30 vol%

J. A. Partridge; G. P. Bosuego

1980-01-01

356

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

SciTech Connect

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

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

2007-09-01

357

Porous clay-organic composites: Potential substitutes for polystyrene foam  

Microsoft Academic Search

Porous clay-organic composites have been prepared by lyophylization of mixtures of clay and organic sols. They are shown to have properties applicable for packing and for use as insulating buffer material. The organics which have been used are all naturally reproduceable in the biosphere. The relations between the organic:clay ratio, the pore size and the mechanical properties have been studied

Shun-ichi Ohta; Hiromoto Nakazawa

1995-01-01

358

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

359

Estimation of quantum finite mixtures  

SciTech Connect

We consider the problem of determining the weights of a quantum ensemble. That is to say, given a quantum system that is in a set of possible known states according to an unknown probability law, we give strategies to estimate the individual probabilities, weights, or mixing proportions. Such strategies can be used to estimate the frequencies at which different independent signals are emitted by a source. They can also be used to estimate the weights of particular terms in a canonical decomposition of a quantum channel. The quality of these strategies is quantified by a covariance-type error matrix. According with this cost function, we give optimal strategies in both the single-shot and multiple-copy scenarios. The latter is also analyzed in the asymptotic limit of large number of copies. We give closed expressions of the error matrix for two-component quantum mixtures of qubit systems. The Fisher information plays an unusual role in the problem at hand, providing exact expressions of the minimum covariance matrix for any number of copies.

Vicente, J. I. de; Calsamiglia, J.; Munoz-Tapia, R.; Bagan, E. [Grup de Fisica Teorica, Facultat de Ciencies, Edifici Cn, Universitat Autonoma de Barcelona, E-08193 Bellaterra, Barcelona (Spain)

2010-01-15

360

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

ERIC Educational Resources Information Center

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

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

2011-01-01

361

Robust Cluster Analysis via Mixture Models  

Microsoft Academic Search

Finite mixture models are being increasingly used to model the distributions of a wide variety of random phenomena and to cluster data sets. In this paper, we focus on the use of normal mixture models to cluster data sets of continuous multivariate data. As normality based methods of estima- tion are not robust, we review the use of t component

Geoffrey J. McLachlan; Shu-Kay Ng; Richard Bean

362

Empirical profile mixture models for phylogenetic reconstruction  

Microsoft Academic Search

Motivation: Previous studies have shown that accounting for site- specific amino acid replacement patterns using mixtures of stationary probability profiles offers a promising approach for improving the robustness of phylogenetic reconstructions in the presence of satu- ration. However, such profile mixture models were introduced only in a Bayesian context, and are not yet available in a Maximum Like- lihood framework.

Le Si Quang; Olivier Gascuel; Nicolas Lartillot

2008-01-01

363

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

364

On the quantitative genetics of mixture characters.  

PubMed

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

Gianola, Daniel; Heringstad, Bjorg; Odegaard, Jorgen

2006-08-01

365

Modified asphalt mixtures resistance to permanent deformations  

Microsoft Academic Search

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

Piotr Radziszewski

2007-01-01

366

Performance investigation on new refrigerant mixture  

Microsoft Academic Search

this research presents a theoretical investigation on the performance of a vapour compression refrigerating system using different mixtures of Hydrocarbons and Hydrofluorocarbons refrigerants as a refrigerant. Genetic Algorithm method was used to solve a nonlinear constrained optimization problem for the selection of the best blend. The performance of new mixtures of Hydrocarbons and Hydrofluorocarbons refrigerants is compared with the performance

E. Khorshid; B. Alshriaan; A. Alsairafi; A. Alazemi; A. Alhaddad

2011-01-01

367

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.

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

1988-01-01

368

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

369

Mixtures of planetary ices at extreme conditions  

Microsoft Academic Search

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

Mal-Soon Lee; Sandro Scandolo

2011-01-01

370

Evaluating permanent deformation in asphalt rubber mixtures  

Microsoft Academic Search

Permanent deformation or rutting, one of the most important distresses in flexible pavements, has long been a problem in asphalt mixtures, mainly in countries with high temperatures such as Brazil. Throughout the years, researchers have used different test methods to estimate the rutting performance of asphalt mixtures. One of the alternatives to reduce permanent deformation in asphalt pavement layers is

Liseane P. T. L. Fontes; Glicério Trichês; Jorge C. Pais; Paulo A. A. Pereira

2010-01-01

371

RENAL CANCER STUDIES OF DRINKING WATER MIXTURES  

EPA Science Inventory

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

372

Oxidative particle mixtures for groundwater treatment  

Microsoft Academic Search

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

Robert L. Siegrist; Lawrence C. Murdoch

2000-01-01

373

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

374

Preferential solvation of acridine in binary mixtures  

NASA Astrophysics Data System (ADS)

Preferential solvation studies of acridine have been investigated using optical absorption technique. The preferential solvation parameter shows that in dimethyl formamide (DMF) + ethanol mixture, the acridine is preferentially solvated by ethanol in DMF rich region and by DMF in ethanol rich region. In the case of DMF + Carbon tetrachloride mixture acridine is preferentially solvated by DMF.

Umadevi, M.; Christy, A. Jegatha; Sudha, R. Helan; Rajkumar, Beulah J. M.; Ramakrishnan, V.

2008-12-01

375

Condensing from Vapor-Gas Mixtures.  

National Technical Information Service (NTIS)

Designing condensers for vapor-gas mixtures is far more complex than for vapors alone. This simplified design method eliminates the old trial-and-error procedures. Condensation of vapor from a vapor-gas mixture where the gas does not condense is quite dif...

F. Votta

1964-01-01

376

Thermal analysis of pyrotechnical mixtures, I  

Microsoft Academic Search

The author investigated a two-component pyrotechnical mixture used in the manufacture of delay detonators. Comparing the thermogravimetric, derivative thermogravimetric and differential thermal analysis curves of components with that of mixtures containing the components in different ratios, a relation has been found between the reaction rate and ratio. Initial temperature of reaction can be defined as well. Release of oxygen and

L. Sulacsik

1973-01-01

377

Two-Microphone Separation of Speech Mixtures  

Microsoft Academic Search

Separation of speech mixtures, often referred to as the cocktail party problem, has been studied for decades. In many source separation tasks, the separation method is limited by the assumption of at least as many sensors as sources. Further, many methods require that the number of signals within the recorded mixtures be known in advance. In many real-world applications, these

Michael Syskind Pedersen; Deliang Wang; Jan Larsen; Ulrik Kjems

2008-01-01

378

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

379

THE RECOVERY OF URANIUM FROM GAS MIXTURE  

Microsoft Academic Search

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

Jury

1964-01-01

380

Supervised dimensionality reduction using mixture models  

Microsoft Academic Search

Given a classication problem, our goal is to nd a low-dimensional linear transformation of the feature vectors which retains informa- tion needed to predict the class labels. We present a method based on maximum condi- tional likelihood estimation of mixture mod- els. Use of mixture models allows us to ap- proximate the distributions to any desired accuracy while use of

Sajama; Alon Orlitsky

2005-01-01

381

Dielectric Properties of a Nematic Binary Mixture  

Microsoft Academic Search

In this paper, a phase diagram is developed for the molar mixtures of nematic liquid crystals of 5CB and MBBA. In order to understand the interaction of the two systems, dielectric permittivities ˜? and ˜? were measured for mixtures of various concentrations. The usual assumption is that in the absence of chemical reactions the bulk physical properties add up as

Shila Garg; Tom Spears

2004-01-01

382

Literaturstudie und experimentelle Untersuchungen zur Bildung von organischen Iodverbindungen aus Alkan-Dampf/Luft-Gemischen mit Radioiod im Strahlenfeld. (Literature study and experimental investigations into the production of organic iodine compounds from alkane-vapour/air mixtures with radioiodine in the radiation field).  

National Technical Information Service (NTIS)

It was assumed in these investigations that these compounds originated in the gas phase by irradiation induced reactions with radioiodine. Alkane(methane, ethane, propane, n-butane) vapour/air mixtures were radiolysed with iodine in a Co-60 gamma source. ...

W. Leskopf S. Holl K. Bleier

1992-01-01

383

Evaluating virial coefficients for multicomponent mixtures: hard sphere mixtures and flexible chains  

Microsoft Academic Search

A new algorithm to compute the virial coefficients of multicomponent mixtures is proposed. The number of graphs that must be evaluated increases dramatically in a multicomponent mixture so that it becomes difficult to enumerate and compute all possible graphs. However, once all of them are known and evaluated, the virial coefficient of the mixture can be evaluated for any composition.

C. Vega

2000-01-01

384

Organic chemistry on Titan  

NASA Technical Reports Server (NTRS)

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

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

1979-01-01

385

Raman spectra of solid isotopic hydrogen mixtures  

NASA Astrophysics Data System (ADS)

Rotational and vibrational Raman spectra are investigated for mixtures of hydrogen isotopes in the solid phase. The S0(0) rotational Raman transitions are asymmetrically broadened in energy for each isotope in the mixture compared to their respective pure component transitions. The isotopic energy shift of S0(0) breaks the lattice symmetry and limits the roton hopping responsible for the well defined S0(0) triplet found in the pure component. The S0(0) line shapes of tritiated and nontritiated mixtures are nearly identical, and shows there is little effect from radiation damage. The vibrational Q1(J) lines are shifted to higher energy, and the Q1(1)/Q1(0) intensity ratio is decreased in the mixtures relative to the pure component. Both effects are due to a localization of the vibrons in mixtures.

Kozioziemski, B. J.; Collins, G. W.

2003-05-01

386

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

387

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

388

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

389

Identification and separation of the organic compounds in coal-gasification condensate waters  

SciTech Connect

A substantial fraction of the organic solutes in condensate waters from low-temperature coal-gasification processes are not identified by commonly employed analytical techniques, have low distribution coefficients (K/sub D/) into diisopropyl ether (DIPE) or methyl isobutyl ketone (MIBK), and are resistant to biological oxidation. These compounds represent an important wastewater treatment problem. Analytical techniques were developed to detect these polar compounds, the the liquid-liquid phase equilibria were measured with several solvents. A high-performance liquid chromatography (HPLC) technique was employed to analyze four condensate-water samples from a slagging fixed-bed gasifier. A novel sample-preparation technique, consisting of an azeotropic distillation with isopropanol, allowed identification of compounds in the HPLC eluant by combined gas chromatography and mass spectrometry. Solvents containing trioctyl phosphine oxide (TOPO) have high K/sub D/ values for phenol and dihydroxy benzenes. A fraction of the compounds which are not removed by MIBK may be Lewis acids, because some of them were extracted by the strong Lewis bases, TBP and TOPO.

Mohr, D.H. Jr.

1983-01-01

390

Assessing Cumulative Health Risks from Exposure to Environmental Mixtures--Three Fundamental Questions  

PubMed Central

Differential exposure to mixtures of environmental agents, including biological, chemical, physical, and psychosocial stressors, can contribute to increased vulnerability of human populations and ecologic systems. Cumulative risk assessment is a tool for organizing and analyzing information to evaluate the probability and seriousness of harmful effects caused by either simultaneous and/or sequential exposure to multiple environmental stressors. In this article we focus on elucidating key challenges that must be addressed to determine whether and to what degree differential exposure to environmental mixtures contributes to increased vulnerability of exposed populations. In particular, the emphasis is on examining three fundamental and interrelated questions that must be addressed as part of the process to assess cumulative risk: a) Which mixtures are most important from a public health perspective? and b) What is the nature (i.e., duration, frequency, timing) and magnitude (i.e., exposure concentration and dose) of relevant cumulative exposures for the population of interest? c) What is the mechanism (e.g., toxicokinetic or toxicodynamic) and consequence (e.g., additive, less than additive, more than additive) of the mixture’s interactive effects on exposed populations? The focus is primarily on human health effects from chemical mixtures, and the goal is to reinforce the need for improved assessment of cumulative exposure and better understanding of the biological mechanisms that determine toxicologic interactions among mixture constituents.

Sexton, Ken; Hattis, Dale

2007-01-01

391

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.

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

2014-01-01

392

Isobaric vapor–liquid equilibrium for ternary mixtures of ethanol and methylcyclohexane with 3-methylpentane and tert-butyl alcohol at 101.3 kPa  

Microsoft Academic Search

Consistent vapor–liquid equilibrium (VLE) data for the ternary systems 3-methylpentane+ethanol+methylcyclohexane and ethanol+tert-butyl alcohol (TBA)+methylcyclohexane are reported at 101.3kPa. The VLE data have been correlated by Wilson, UNIQUAC and NRTL equations. The ternary systems do not present azeotrope and are well predicted from binary interaction parameters.

María del Carmen Sánchez-Russinyol; Antonio Aucejo; Sonia Loras

2007-01-01

393

Effects of active pharmaceutical ingredients mixtures in mussel Mytilus galloprovincialis.  

PubMed

Active pharmaceutical ingredients (APIs) are emergent environmental contaminants widely detected in surface waters as result of incomplete waste water treatment plant (WWTP) removal processes and improper disposal. The assessment of potential effects of APIs on non-target organisms is still scarce since besides presenting multiple chemical structures, properties and modes of action, these compounds occur as complex mixtures. This study comprises a 15-day exposure of mussels Mytilus galloprovincialis to mixtures (at environmentally relevant nominal concentrations) of non-steroidal inflammatory drugs ibuprofen (IBU) and diclofenac (DCF) (250ngL(-1) each) and selective serotonin reuptake inhibitor (SSRI) fluoxetine (FLX) (75ngL(-1)) (MIX 1) along with the addition of classical pro-oxidant copper (Cu) (5?gL(-1)) (MIX 2). The goals included the assessment of oxidative stress, neurotoxic and endocrine effects on this sentinel species applying both a multibiomarker and gene expression (here and later gene expression is taken as synonym to gene transcription, although it is acknowledged that it is also affected by, e.g. translation, and mRNA and protein stability) analysis approaches. The results revealed a swifter antioxidant response in digestive glands than in gills induced by MIX 1, nevertheless the presence of Cu in MIX 2 promoted a higher lipid peroxidation (LPO) induction. Neither mixture altered acetylcholinesterase (AChE) activity, while both triggered the formation of vitellogenin-like proteins in females confirming the xenoestrogenic effect of mixtures. All these results varied with respect to those obtained in previous single exposure essays. Moreover, RT-PCR analysis revealed a catalase (CAT) and CYP4Y1 gene expression down- and upregulation, respectively, with no significant changes in mRNA levels of genes encoding superoxide dismutase (SOD) and glutathione-S-transferase (GST). Finally, this study highlights variable tissue and time-specific biomarker responses and gene expression alterations, which along with several interactions between each mixture component on each biomarker confirm the susceptibility of mussels to API mixtures. PMID:24630142

Gonzalez-Rey, M; Mattos, J J; Piazza, C E; Bainy, A C D; Bebianno, M J

2014-08-01

394

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

395

Chemical mixtures in untreated water from public-supply wells in the U.S.--occurrence, composition, and potential toxicity.  

PubMed

Chemical mixtures are prevalent in groundwater used for public water supply, but little is known about their potential health effects. As part of a large-scale ambient groundwater study, we evaluated chemical mixtures across multiple chemical classes, and included more chemical contaminants than in previous studies of mixtures in public-supply wells. We (1) assessed the occurrence of chemical mixtures in untreated source-water samples from public-supply wells, (2) determined the composition of the most frequently occurring mixtures, and (3) characterized the potential toxicity of mixtures using a new screening approach. The U.S. Geological Survey collected one untreated water sample from each of 383 public wells distributed across 35 states, and analyzed the samples for as many as 91 chemical contaminants. Concentrations of mixture components were compared to individual human-health benchmarks; the potential toxicity of mixtures was characterized by addition of benchmark-normalized component concentrations. Most samples (84%) contained mixtures of two or more contaminants, each at concentrations greater than one-tenth of individual benchmarks. The chemical mixtures that most frequently occurred and had the greatest potential toxicity primarily were composed of trace elements (including arsenic, strontium, or uranium), radon, or nitrate. Herbicides, disinfection by-products, and solvents were the most common organic contaminants in mixtures. The sum of benchmark-normalized concentrations was greater than 1 for 58% of samples, suggesting that there could be potential for mixtures toxicity in more than half of the public-well samples. Our findings can be used to help set priorities for groundwater monitoring and suggest future research directions for drinking-water treatment studies and for toxicity assessments of chemical mixtures in water resources. PMID:22687436

Toccalino, Patricia L; Norman, Julia E; Scott, Jonathon C

2012-08-01

396

Mixture model clustering of binned uncertain data: the classification approach  

Microsoft Academic Search

Basing cluster analysis on Gaussian mixture models is a powerful approach. In this context, two commonly used maximum likelihood approaches have been proposed: the mixture approach and the classification approach. Loosely speaking, the mixture approach aims to maximize the likelihood over the mixture parameters, whereas the classification approach aims to maximize the likelihood over the mixture parameters and over the

H. Hamdan

2006-01-01

397

Kinetics of Phase Separation in Binary Mixtures  

NASA Astrophysics Data System (ADS)

We present numerical simulation results of the phase separation kinetics in three-dimensional symmetric binary fluid mixtures and binary solid mixtures. In the former system, our extensive molecular dynamics simulation is able to probe an extended period where the domain size grows linearly with time, leading to an unambiguous confirmation of the viscous hydrodynamic regime. On the other hand, for the binary solid mixture, we use Monte Carlo simulation with spin-exchange dynamics to verify the Lifshitz-Slyzov growth law. In spite of the differences in the growth mechanisms, the pair correlation functions and structure factors of the two systems overlap, indicating similarity in the morphologies during phase separation.

Ahmad, Shaista; Das, Subir K.; Puri, Sanjay

2013-03-01

398

Anomalies in some properties of powder mixtures.  

PubMed

Mixtures of lactose and paracetamol and of lactose and oxytetracycline exhibit anomalous properties. The mean particle sizes, tensile strengths and flow properties of the mixtures are not proportionally intermediate between those of the constituents. The results are ascribed to changes that occur in the packing arrangements of the particles. These changes could have practical consequences in monitoring the progress of a mixing operation by measuring apparent particle size and in controlling the properties of granules, capsules and tablets prepared from the mixtures. PMID:6749

Varthalis, S; Pilpel, N

1976-05-01

399

Hormesis in mixtures -- can it be predicted?  

PubMed

Binary mixture studies are well established for mixtures of pollutants, pesticides, or allelochemicals and sound statistical methods are available to evaluate the results in relation to reference models. The majority of mixture studies are conducted to investigate the effect of one compound on the inhibitory action of another. However, since stimulatory responses to low concentrations of chemicals are gaining increased attention and improved statistical models are available to describe this phenomenon of hormesis, scientists are challenged by the question of what will happen in the low concentration range when all or some of the chemicals in a mixture induce hormesis? Can the mixture effects still be predicted and can the size and concentration range of hormesis be predicted? The present study focused on binary mixtures with one or both compounds inducing hormesis and evaluated six data sets of root length of Lactuca sativa L. and areal growth of Lemna minor L., where substantial and reproducible hormetic responses to allelochemicals and herbicides have been found. Results showed that the concentration giving maximal growth stimulatory effects (M) and the concentration where the hormetic effect had vanished (LDS) could be predicted by the most-used reference model of concentration addition (CA), if the growth inhibitory concentrations (EC50) followed CA. In cases of deviations from CA at EC50, the maximum concentration M and the LDS concentration followed the same deviation patterns, which were described by curved isobole models. Thus, low concentration mixture effects as well as the concentration range of hormesis can be predicted applying available statistical models, if both mixture partners induce hormesis. Using monotonic concentration-response models instead of biphasic concentration-response models for the prediction of joint effects, thus ignoring hormesis, slightly overestimated the deviation from CA at EC20 and EC50, but did not alter the general conclusion of the mixture study in terms of deviation from the reference model. Mixture effects on the maximum stimulatory response were tested against the hypothesis of a linear change with mixture ratio by constructing 95% prediction intervals based on the single concentration-response curves. Four out of the six data sets evaluated followed the model of linear interpolation reasonably well, which suggested that the size of the hormetic growth stimulation can be roughly predicted in mixtures from knowledge of the concentration-response relationships of the individual chemicals. PMID:18640701

Belz, Regina G; Cedergreen, Nina; Sørensen, Helle

2008-10-01

400

Plasma jet ignition in turbulent lean mixtures  

SciTech Connect

In order to confirm quantitatively the performance and characteristics of the plasma jet ignition in turbulent lean mixtures, combustion tests were carried out in a disk-shaped combustion chamber with lean turbulent methane-air mixtures. In the tests, the governing parameters of the plasma jet ignition such as the plasma cavity size, the orifice diameter, and the discharge energy were varied. In this paper characteristic lifetime and a characteristic length of the plasma jet and an entrainment volume of the mixture into the plasma jet is defined theoretically and expressed by the parameters of the plasma jet ignition.

Murase, E.; Ono, S.; Hanada, K.; Nakahara, S.

1989-01-01

401

Mixture Models for Web Page Classification  

NASA Astrophysics Data System (ADS)

This paper presents a method for designing semi-supervised classifier trained on labeled and unlabeled instances. We explore the trade-off maximizing a generative likelihood of labeled and unlabeled data. Moreover, mixture models are an interesting and flexible model family. The different uses of mixture models include for example generative models and density estimation. This paper investigates semi-supervised learning of mixture models using a unified objective function taking both labeled and unlabeled data into account. We conducted experiments on the WebKB and 20NEWSGROUPS. The results show that unlabeled data results in improvement in classification accuracy over the supervised model.

JingHua, Bai; Xiao Xian, Zhang; ZhiXin, Li; XiaoPing, Li

402

Nucleate pool boiling of hydrocarbon mixtures  

SciTech Connect

The Schlunder method can be correctly used to predict boiling heat transfer coefficient of multicomponent hydrocarbon mixtures. The method was tested against experimental mixtures containing up to five components. The Stephan-Abdelsalam correlation can be used to calculate a ''pseudo-single component'' boiling heat transfer coefficient for a mixture using weighted properties. The effective temperature driving force term and the high mass flux correction term in the Schlunder formulation are empirically adjusted to improve the accuracy of prediction. Predictions of the Schlunder method are sensitive to the VLE calculations. The UNIFAC method is used in this study for reasons discussed in the paper.

Sardesai, R.G.; Palen, J.W.; Thome, J.

1986-01-01

403

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...

404

Organ Facts  

MedlinePLUS

... Lung Kidney Pancreas Kidney/Pancreas Liver Intestine Organ Facts Here you can find valuable information about organs ... Camps for kids Contacting my donor family Data Facts about living donation Financing a transplant Matching organs ...

405

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...

406

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

Microsoft Academic Search

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

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

1999-01-01

407

Organic constituents of carbonaceous chondrites.  

PubMed

From a brief discussion of forms of meteorite carbon it is concluded that almost all the carbon in the carbonaceous chondrites is present as organic matter. Attempts to extract and identify this organic matter are then reviewed. It is shown that only 25 per cent has been extracted and only about 5 per cent chemically characterized. Of this 5 per cent, most is a complex mixture of hydroxylated aromatic acids together with various hydrocarbons of the paraffin, naphthene and aromatic series. Small amounts of amino acids, sugars and fatty acids also are present. The possible chemical nature of the major fraction is discussed. It is suggested to be a mixture of high-molecular weight aromatic and hydrocarbon polymers. Possible sources of contamination of the meteorites are described and evidence indicating a general lack of organic contaminants is presented. It is concluded, that most of the organic constituents are indigenous to the meteorites and are extra terrestrial in origin. Synthetic processes for the compounds are mentioned and it is concluded that the organic material is probably of abiogenic origin. A brief review on studies of "organized elements" contained within the meteorites is presented. Difficulties of identification are discussed and photographs of some microstructures of several carbonaceous chondrites are presented. No final conclusion about the nature of these objects is possible, but some appear to be various indigenous organic and mineral structures, while others are terrestrial contaminants. PMID:11881656

Briggs, M H; Mamikunian, G

1964-01-01

408

Method for preparing a mixture of saccharides  

US Patent & Trademark Office Database

A method for preparing a mixture of fructose, glucose and compounds of the general formula GF.sub.n, wherein G is glucose and F is fructose and n is an integer. The mixture is recovered from plant tubers or roots by means of a method which does not involve any chemical modification of the components of the mixture. A juice or syrup comprising fructose, glucose, sucrose and oligosaccharides is subjected at one or more suitable steps to a physical separation process to reduce the amount of fructose, glucose and sucrose. The physical separation may be carried out by chromatography or nanofiltration or both. The mixture is suitable for use in foodstuffs and beverages for human beings and animals.

1993-10-19

409

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.

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

1993-01-01

410

Tests for Finite Mixtures of Distributions.  

National Technical Information Service (NTIS)

Derive and discuss properties of three approaches to test the hypothesis of finite proper mixtures of distributions. Two of them are compared for the case of two normal components against a single normal alternative. The third is investigated by simulatio...

C. F. Hsu

1977-01-01

411

Supercritical Fluid Extraction of Liquid Hydrocarbon Mixtures.  

National Technical Information Service (NTIS)

The thesis presents the results of a study on the separation of liquid hydrocarbon mixtures with various supercritical solvents. First a study on the separation of alkanes and aromatics has been made to identify whether supercritical solvents separate hyd...

A. B. de Haan

1991-01-01

412

Supercritical Fluid Extraction of Liquid Hydrocarbon Mixtures.  

National Technical Information Service (NTIS)

Results of a study on the separation of liquid hydrocarbon mixtures with various supercritical solvents are presented. The equipment and experimental procedure are discussed and the separation of high boiling alkanes and aromatics with supercritical carbo...

A. B. Dehaan

1991-01-01

413

Quantiles for Finite Mixtures of Normal Distributions  

ERIC Educational Resources Information Center

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

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

2006-01-01

414

Thermodynamical Inequalities, Reciprocal Relations and Mixtures.  

National Technical Information Service (NTIS)

A thermodynamical inequality is obtained for mixtures of interacting continua; it represents the analogue of a corresponding inequality for single phase media and is less restrictive than one proposed earlier. Also, the use of such inequalities in conjunc...

A. E. Green P. M. Naghdi

1989-01-01

415

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...

416

14 CFR 25.1147 - Mixture controls.  

Code of Federal Regulations, 2011 CFR

...Separate control of each engine; and (2) Simultaneous control of all engines. (b) Each intermediate position of the mixture controls that corresponds to a normal...if there is a separate flight engineer station with...

2014-01-01

417

14 CFR 23.1147 - Mixture controls.  

Code of Federal Regulations, 2011 CFR

...single-engine airplanes, each manual engine mixture control must be designed so that, if the control separates at the engine fuel metering device, the airplane is capable of continued safe flight and landing. [Doc. No....

2014-01-01

418

Fluctuating hydrodynamics of multispecies nonreactive mixtures.  

PubMed

In this paper we discuss the formulation of the fluctuating Navier-Stokes equations for multispecies, nonreactive fluids. In particular, we establish a form suitable for numerical solution of the resulting stochastic partial differential equations. An accurate and efficient numerical scheme, based on our previous methods for single species and binary mixtures, is presented and tested at equilibrium as well as for a variety of nonequilibrium problems. These include the study of giant nonequilibrium concentration fluctuations in a ternary mixture in the presence of a diffusion barrier, the triggering of a Rayleigh-Taylor instability by diffusion in a four-species mixture, as well as reverse diffusion in a ternary mixture. Good agreement with theory and experiment demonstrates that the formulation is robust and can serve as a useful tool in the study of thermal fluctuations for multispecies fluids. PMID:24580330

Balakrishnan, Kaushik; Garcia, Alejandro L; Donev, Aleksandar; Bell, John B

2014-01-01

419

Liquid viscosities of multi-component mixtures  

NASA Astrophysics Data System (ADS)

McAllister's theory of viscosity of liquid mixtures was modified in order to account for temperature dependencies different than that predicted by the Eyring model. By means of an Antoine type equation and restricting the interactions to three-bodied interactions in the single plane a more valid correlation technique was established for predicting the viscosities of the binary, ternary, and multi-component liquid mixtures. The resulting equation was tested with the experimentally obtained viscosity data of 41 binary and 16 ternary mixtures containing polar as well as nonpolar components. The improved version of the McAllister equation appears to be suited to represent viscosity data of binary and ternary mixtures than other equations that may be found in the literature.

Dizechi, M.

1980-03-01

420

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

421

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

Microsoft Academic Search

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

R. Krishna; J. M. van Baten

2009-01-01

422

Spectroscopic identification and quantitative analysis of binary mixtures using artificial neural networks.  

PubMed

This work deals with the application of artificial neural networks to two common problems in spectroscopy: the identification of distorted UV-visible spectra of a specific class of organic compounds, and the quantitative determination of single components in binary mixtures of these compounds. The examined species were six organic indicators, whose spectra are very similar to each other; the trained networks have proven to be very powerful in both applications. PMID:18966932

Ganadu, M L; Lubinu, G; Tilocca, A; Amendolia, S R

1997-10-01

423

Asbestos tailings as aggregates for asphalt mixture  

Microsoft Academic Search

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

Xiaoming Liu; Linrong Xu

2011-01-01

424

Health risk assessment of chemical mixtures  

SciTech Connect

This overview has briefly reviews the complexity of chemical mixtures, their sources, the relevance of exposure, the various interactions of chemical components, and new approaches for measuring exposure. Current quantitative risk assessment by linear extrapolation is inadequate in estimating risks. The new emerging methodology offers a scientific and realistic alternative in assessment of risks from various exposures to both natural and man-made chemical mixtures.

Witz, G.; Mehlman, M.A.

1987-07-01

425

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

426

Polymer thermophoresis in solvents and solvent mixtures  

Microsoft Academic Search

The thermophoresis of homopolymer chains dissolved in a pure non-electrolyte solvent or solvent mixture is theoretically examined. Thermophoresis is related to the temperature-dependent pressure gradient in the solvent layer surrounding the monomer units (mers). The gradient is produced by small changes in the solvent or solvent mixture density due to the mer-solvent interaction. The London-van der Waals interaction was considered

Martin E. Schimpf; Semen N. Semenov

2003-01-01

427

Viscosity Prediction for Natural Gas Mixtures  

Microsoft Academic Search

The viscosity of multicomponent natural gas-mixtures containing hydrocarbons (C1 through C7) is predicted by modifying a previously published dilute-gas viscosity model and extending its applicability to a wide range of temperature and pressure conditions including liquid and gas states. Nitrogen, oxygen, carbon dioxide, and helium are also included among components of mixtures for which published viscosity data are available. The

Z. Shan; R. T Jacobsen; S. G. Penoncello

2001-01-01

428

Flow Number as a Discriminating HMA Mixture Property, Brief.  

National Technical Information Service (NTIS)

This research was aimed to: (1) investigate the effect of changes in mixture composition on the flow number and rutting resistance of HMA mixtures from Wisconsin. (2) evaluate the rutting resistance of mixtures used at intersections. (3) recommend improve...

R. Bonaquist

2013-01-01

429

Computer Aided Statistical Analysis of Data from Mixture Experiments  

Microsoft Academic Search

Mixtures of ingredients occur often in both everyday and industrial settings. When forming a mixture, the concern is often how much of each ingredient should be added to create a mixture which is the \\

Chad Michael Schafer

1994-01-01

430

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

431

40 CFR 160.113 - Mixtures of substances with carriers.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Mixtures of substances with carriers. 160...Reference Substances § 160.113 Mixtures of substances with carriers. ...1) To determine the uniformity of the mixture and to determine, periodically,...

2013-07-01

432

40 CFR 792.113 - Mixtures of substances with carriers.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Mixtures of substances with carriers. 792...Reference Substances § 792.113 Mixtures of substances with carriers. ...1) To determine the uniformity of the mixture and to determine, periodically,...

2013-07-01

433

46 CFR 154.1735 - Methyl acetylene-propadiene mixture.  

Code of Federal Regulations, 2010 CFR

...2009-10-01 2009-10-01 false Methyl acetylene-propadiene mixture. 154.1735...Requirements § 154.1735 Methyl acetylene-propadiene mixture. (a) The composition of the methyl acetylene-propadiene mixture at loading...

2009-10-01

434

46 CFR 154.1735 - Methyl acetylene-propadiene mixture.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Methyl acetylene-propadiene mixture. 154.1735...Requirements § 154.1735 Methyl acetylene-propadiene mixture. (a) The composition of the methyl acetylene-propadiene mixture at loading...

2010-10-01

435

Predicting Asphalt Mixture Skid Resistance Based on Aggregate Characteristics.  

National Technical Information Service (NTIS)

The objective of this research project was to develop a method to determine the skid resistance of an asphalt mixture based on aggregate characteristics and gradation. Asphalt mixture slabs with different combinations of aggregate sources and mixture desi...

A. Chowdhury A. Rezaei E. Masad P. Harris

2009-01-01

436

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

437

[Use of enteral immune mixture in program of intensive care for acute parenchimal lung injury].  

PubMed

The article deals with a case of successful acute lung injure syndrome treatment. Patient received enteral nutritive treatment with balanced polysubstrate mixture--immune liquid additionally to antibacterial, infusion, respiratory and symptomatic therapy. The case shows that immune liquid corrects hypermetabolic syndrome and effects on decreasing of organs dysfunctions especially lung dysfunction. PMID:24341001

Iudakova, T N; Girsh, A O

2013-01-01

438

Effects of mixtures of oleic acid with chlorinated herbicides on Vibrio fischeri bacteria  

Microsoft Academic Search

Abbreviations: D, diuron; EC50, effective concentration,causing the inhibition of function fifty per cent; EDTA, ethylenediamine tetraacetic acid; FAs, fatty acids; M, monuron; OA, oleic acid; OP, organochlorine pollutants; POM, par- ticular organic matter The toxicity of chlorinated phenylurea herbicides and their mixtures with monoun- saturated oleic (fatty) acid, OA, to bioluminescence of Vibrio fischeri was investiga- ted. The EC50 of

A. Èetkauskaitë; J. Braþënaitë

439

Modeling of Drying of Gaseous Mixtures in TSA System with Fixed Bed of Solid Desiccants  

Microsoft Academic Search

A nonisothermal, nonequilibrium mathematical model was developed to theoretically analyze adsorptive drying of gaseous mixtures containing water and volatile organic compounds (VOCs). The analysis concerns a four-bed cyclic temperature swing adsorption (TSA) system. The two fixed beds are formed of silica gel primarily as the water vapor adsorbent. The other two consist of activated carbon as the adsorbent of the

J. Nastaj; B. Ambro?ek

2012-01-01

440

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

441

Effect of various gas mixtures on plasma cleaned ceramics. Final report. [Electronic components  

Microsoft Academic Search

Activated gas plasma cleaning efficiencies of various gas mixtures were studied for the preparation of ceramic parts. Differences in the ease of removal of organic residue are shown by Auger analyses for the various gases. A reduction in plasma process time is shown to be possible, and gases are compared with oxygen on the basis of cleaning efficiency. The plasma

1979-01-01

442

Chronic mixture toxicity study of Clophen A60 and diethyl phthalate in male rats  

Microsoft Academic Search

Chemical mixtures are an important area of research as individuals are exposed to low doses of persistent chemical agents known as environmental pollutants throughout their life time. Polychlorinated biphenyls (PCBs) and diethyl phthalate (DEP) are ubiquitous environmental pollutants that could be present in the same environmental compartment; hence organisms may get simultaneously exposed to both. Therefore, a study was undertaken

Contzen Pereira; Kranti Mapuskar; C. Vaman Rao

2008-01-01

443

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

444

Isobaric vapor–liquid equilibria of water–pyridine and water–pyridine–calcium chloride mixtures  

Microsoft Academic Search

Isobaric vapor–liquid equilibrium data at 705±1mmHg for the systems water–pyridine and water–pyridine–CaCl2 were obtained using the modified Othmer circulation still. The experimental data for the water–pyridine system exhibited an azeotropic point at a water composition of 75.0mol% and a temperature of 92.60°C. The isobaric salt-free binary data were compared with predicted vapor–liquid equilibrium (VLE) data using the UNIFAC model. Good

Fahmi A Abu Al-Rub; Ravindra Datta

2001-01-01

445

Chiral separation of lobeline and benzhexol by capillary electrophoresis using the reaction mixture of ?-cyclodextrin, phosphorous-pentoxide and l-glutamic acid as chiral selector  

Microsoft Academic Search

The reaction mixture of ?-cyclodextrin, phosphorous-pentoxide and l-glutamic acid was successfully used as chiral selector in capillary zone electrophoresis. The reaction process and the main properties of the reaction mixture was introduced in detail. The enantiomeric separation of lobeline and benzhexol were investigated. The chiral resolution was strongly influenced by the concentration of the reaction mixture, pH and the organic

Xiuli Lin; Guanbin Li; Wenqiang Jiang; Yongbao Chu; Pei Wu; Guan Yafeng

2001-01-01

446

Organic, Dude  

NSDL National Science Digital Library

The word organic has lots of meanings in everyday life. Organic vegetables are ones grown without pesticides and organic beef comes from cattle that haven't been given antibiotics. When it comes to chemistry, organic sometimes means something else, and you're about to find out what that is.

Robertson, William C.

2007-01-01

447

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

Microsoft Academic Search

In this paper we provide a brief review of the basic equations for the flow of two linearly viscous fluids using the mixture theory equations given in Atkin and Craine [R.J. Atkin, R.E. Craine, Continuum theories of mixtures: applications, J. Inst. Math. Appl. 17 (1976) 153; R.J. Atkin, R.E. Craine, Continuum theories of mixtures: basic theory and historical development, Quart.

Mehrdad Massoudi; Mehrdad

2008-01-01

448

Evaluating virial coeç cients for multicomponent mixtures: hard sphere mixtures andexible chains  

Microsoft Academic Search

A new algorithm to compute the virial coeÅ cients of multicomponent mixtures is proposed. The number of graphs that must be evaluated increases dramatically in a multicomponent mixture so that it becomes diÅ cult to enumerate and compute all possible graphs. However, once all of them are known and evaluated, the virial coeÅ cient of the mixture can be evaluated

C. VEGA

2000-01-01

449

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

450

Wet ashing of organic matter for the determination of antimony  

Microsoft Academic Search

The wet ashing of organic matter for Sb determination was investigated by using a radioactive tracer technique. Wet ashing with HNOâ + HClOâ mixtures leads to the formation of insoluble Sb compounds. All the Sb remains in solution when a HNOâ + HClOâ + HâSOâ mixture is used. The influence of the ashing vessel (glass and Teflon) and the oxidation

Sixto. Bajo; Ursula. Suter

1982-01-01

451

Molecular interactions in poly(ethylene glycol)-water mixtures at various temperatures: density and isentropic compressibility study.  

PubMed

The densities and sound velocities of mixtures of water with poly(ethylene glycol), poly(ethylene glycol) monomethylether, and poly(ethylene glycol) dimethylether with mean molar weights between 250 and 500 have been measured as a function of mixture composition and temperature between 10 and 40 degrees C. Isentropic compressibilities are derived from the data and are compared to those for the ethylene glycol/water system and for other organic solvent/water mixtures. Relative minima in the mixture volume to ideal volume ratio and in the dependence of the compressibility upon mixture composition are discussed in terms of the conformational variability of the chainlike oligomers, of hydrogen-bonded networks, and of water clusters between the oligomer chains. PMID:17262864

Hanke, Elke; Schulz, Ulrike; Kaatze, Udo

2007-03-12

452

High Efficiency Organic Photovoltaic Cells Employing Hybridized Mixed-Plannar Heterojunctions.  

National Technical Information Service (NTIS)

A device is provided, having a first electrode, a second electrode, and a photoactive region disposed between the first electrode and the second electrode. The photoactive region includes a first organic layer comprising a mixture of an organic acceptor m...

B. Rand J. Xue S. Uchida S. R. Forrest

2004-01-01

453

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

DOEpatents

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

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

2011-08-23

454

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...

455

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

456

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

457

Fluorescence spectroscopy of complex aromatic mixtures.  

PubMed

The contribution of two- to seven-ring polycyclic aromatic hydrocarbons (PAH) and of larger aromatic structures contained in complex PAH-laden mixtures collected in flames was evaluated by fluorescence spectroscopy. A composition procedure of the fluorescence spectra of individual PAHs, analyzed by gas chromatography/mass spectrometry (GC/MS) was applied for the evaluation of their contribution to the fluorescence spectra of PAH-laden mixtures. In this way, it was possible to put in evidence the contribution to the total fluorescence spectrum of high molecular weight aromatic species present in the PAH-laden mixtures and not detectable by GC/MS. Qualitative and quantitative interpretation of synchronous and conventional fluorescence spectra of PAH-laden mixtures formed in combustion processes was proposed. The composition procedure was showed to be reliable in the UV-visible region for samples dissolved in cyclohexane solutions, but failed in the UV region when the solvent contained heavy atoms, as in the case of dichloromethane. However, the heavy-atom solvent effect was not sufficient to explain the depression of the UV fluorescence signal. Energy transfer interaction between fluorene and other fluorescing PAHs was suggested to be also responsible for this effect on the basis of fluorescence studies performed on single PAHs and their mixtures in cyclohexane, methanol, and dichloromethane. PMID:15053681

Apicella, Barbara; Ciajolo, Anna; Tregrossi, Antonio

2004-04-01

458

Influence of clover species in mixtures with grasses on fatty acid composition of mixtures  

Microsoft Academic Search

White clover (WC, Trifolium repens L.) or red clover (RC, Trifolium pratense L.) was grown in mixture with grasses. Samples of the mixtures and pure clovers were taken during three cuts, and the fatty acids (FA) compositions were determined. The clover species had no significant effect on the individual FA contents of the leys (g kg -1 dry matter (DM)),

Langeland Å

459

Viscosities of nonelectrolyte liquid mixtures. III. Selected binary and quaternary mixtures  

NASA Astrophysics Data System (ADS)

This paper is the final in a series of three viscosity and density studies of pure n-alkanes and selected binary and quaternary mixtures. A standard U-tube viscometer was used for viscosity measurements, and a Pyrex flask-type pycnometer was used for density determinations. Results are given here for pure alkane and selected binary mixtures of n-tetradecane + n-octane, for selected quaternary mixtures of n-hexadecane + n-dodecane + n-decane + n-hexane, and for pure and selected quaternary mixtures of n-hexadecane + n-dodecane + n-nonane + n-heptane at 303.16 and 308.16 K. The principle of congruence was tested, as was the Grunberg and Nissan equation, as they have been shown to be useful as prediction techniques for other n-alkane binary mixtures. Comparisons were made between the two groups of quaternary alkane mixtures and the binary n-tetradecane + n-octane mixtures of the same “pseudo” composition to understand better the dependence of mixture viscosities on the composition parameter.

Wakefield, D. L.

1988-05-01

460

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

Microsoft Academic Search

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

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

2011-01-01