These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

Separation of organic azeotropic mixtures by pervaporation  

SciTech Connect

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

Baker, R.W.

1991-12-01

2

Separation of organic azeotropic mixtures by pervaporation. Final technical report  

SciTech Connect

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

Baker, R.W.

1991-12-01

3

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

4

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

5

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

6

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

7

Gas viscosities of azeotropic mixtures of the halogenated hydrocarbons R500, R502, and R503  

Microsoft Academic Search

Gas viscosities of azeotropic mixtures R500 (dichlorodifluoromethane (R12)-1, 1-difluoroethane (R152a)), R 502 (chlorodifluoromethane (R22)-chloropentafluoroethane (R115)), and R503 (chlorotrifluoromethane (R13)-trifluoromethane (R23)) were measured with an oscillating disk viscometer of the Maxwell type at 273.15-423.15 K up to 7.5 MPa. Two empirical equations for the viscosities were obtained; one is for the atmospheric viscosities as a function of temperature, and the other

Mitsuo Takahashi; Chiaki Yokoyama; Shinji Takahashi

1988-01-01

8

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

9

Analysis of Closed Multivessel Batch Distillation of Ternary Azeotropic Mixtures  

E-print Network

the need for pre­calculated vessel holdups and makes the closed operating policy flexible and simple with a condenser vessel for sep­ aration of (ideal) binary mixtures. Kiva et al. (1988) ex­ tended this idea operation. TC TC Reboiler Vessel Condenser D Middle 3 2 1 2 1 x + 1 2 B x F 1 N N N D x x x x M x M B N

Skogestad, Sigurd

10

Gas viscosities of azeotropic mixtures of the halogenated hydrocarbons R500, R502, and R503  

SciTech Connect

Gas viscosities of azeotropic mixtures R500 (dichlorodifluoromethane (R12)-1, 1-difluoroethane (R152a)), R 502 (chlorodifluoromethane (R22)-chloropentafluoroethane (R115)), and R503 (chlorotrifluoromethane (R13)-trifluoromethane (R23)) were measured with an oscillating disk viscometer of the Maxwell type at 273.15-423.15 K up to 7.5 MPa. Two empirical equations for the viscosities were obtained; one is for the atmospheric viscosities as a function of temperature, and the other is for the viscosities in the whole range of the present measurement as a function of temperature and density.

Takahashi, M.; Yokoyama, C.; Takahashi, S.

1988-07-01

11

Experimental investigation of moderately high temperature water source heat pump with non-azeotropic refrigerant mixtures  

Microsoft Academic Search

Experimental investigations were carried out on non-azeotropic refrigerant mixtures, named M1A (mass fraction of 20%R152a and 80%R245fa), M1B (mass fraction of 37% R152a and 63%R245fa) and M1C (mass fraction of 50%R152a and 50%R245fa), based on a water-to-water heat pump system in the condensing temperature range of 70–90°C with a cycle temperature lift of 45°C. Performance of R245fa was tested for

Shengjun Zhang; Huaixin Wang; Tao Guo

2010-01-01

12

Modeling of a heat pump charged with a non-azeotropic refrigerant mixture  

NASA Astrophysics Data System (ADS)

An analysis of the vapor compression cycle and the main components of an air-to-air heat pump charged with a binary non-azeotropic mixture has been performed for steady-state operation. The general heat pump simulation model HPBI has been formulated which is based on independent, analytical models of system components and the logic linking them together. The logic of the program requires an iterative solution of refrigerant pressure and enthalpy balances, and refrigerant mixture and individual mixture component mass inventories. The modeling effort emphasis was on the local thermodynamic phenomena which were described by fundamental heat transfer equations and equation of state relationships among material properties. In the compressor model several refrigerant locations were identified and the processes taking place between these locations accounted for all significant heat and pressure losses.

Domanski, P.

1986-01-01

13

Performance of a residential heat pump operating with a non-azeotropic binary refrigerant mixture - an interim report. [R22 vs non-azeotropic binary mixture of R13B1 and R152a  

Microsoft Academic Search

This report presents results of laboratory measurement of the performance change of a substantially unmodified residential heat pump designed for R22 when charged with a non-azeotropic, binary mixture of R13B1 and R152a. Results are presented for various sizes of fixed expansion devices. The effect of gliding temperature in the saturation zone was found to be small. The effect of composition

D. Didion; W. Mulroy

1984-01-01

14

Observation of vapor bubble of non-azeotropic binary mixture in microgravity with a two-wavelength interferometer  

SciTech Connect

Although non-azeotropic mixtures are considered to be promising working fluids in advanced energy conversion systems, the primary technical problems in the heat transfer degradation in phase change processes cause economical handicap to wide-spread applications. The boiling behavior of mixtures still remains a number of basic questions being not answered yet, and the present authors believe that the most essential information for the boiling process in non-azeotropic mixtures is how temperature and concentration profiles are developed around the bubbles. The present study attempts at understanding fundamental heat and mass transfer mechanisms in nucleate pool boiling of non-azeotropic binary mixtures, and with the knowledge to develop a passive boiling heat transfer enhancement eventually. To this end, the authors have employed microgravity environment for rather detailed observation around vapor bubbles in the course of boiling inception and bubble growth. A two-wavelength Mach-Zehnder interferometer has been developed, which withstands mechanical shock caused by gravity change from very low gravity of the order of 10{sup {minus}5} g to relatively high gravity of approximately 8 g exposed during deceleration period. A series of experiments on single vapor bubbles for CFC113 single component and CFC12/CFC112 non-azeotropic binary mixture have been conducted under a high quality microgravity conditions available in 10-second free-fall facility of Japan Microgravity Center (JAMIC). The results for single component liquid showed a strong influence due to Marangoni effect caused by the temperature profile around the bubble. The results for non-azeotropic binary mixture showed, however, considerably different behavior from single component liquid. Both temperature and concentration profiles around a single vapor bubble were evaluated from the interferograms. The temperature and concentration layers established around the bubbles were nearly one order of magnitude larger than those predicted by thermal diffusion and mass diffusion. The temperature and concentration profiles evaluated from the present experiments suggest the role of Marangoni effects due to both concentration profile and temperature profile around the bubble interface.

Abe, Yoshiyuki; Iwasaki, Akira

1999-07-01

15

Separation of organic–organic mixtures by pervaporation—a review  

Microsoft Academic Search

Separation of organic–organic mixtures using membrane separation techniques is being investigated extensively owing to its great importance in chemical and petrochemical industries. Pervaporation is today considered as a basic unit operation for separation of organic–organic liquid mixtures because of its efficiency in separating azeotropic and close-boiling mixtures, isomers and heat-sensitive compounds. Membranes used for separating the four major categories of

B Smitha; D Suhanya; S Sridhar; M Ramakrishna

2004-01-01

16

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...

17

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

SciTech Connect

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

Lundstrom, J.E.

1986-03-01

18

Performance of a residential heat pump operating with a non-azeotropic binary refrigerant mixture - an interim report. [R22 vs non-azeotropic binary mixture of R13B1 and R152a  

SciTech Connect

This report presents results of laboratory measurement of the performance change of a substantially unmodified residential heat pump designed for R22 when charged with a non-azeotropic, binary mixture of R13B1 and R152a. Results are presented for various sizes of fixed expansion devices. The effect of gliding temperature in the saturation zone was found to be small. The effect of composition shift by flash distillation in the accumulator was found to measurably improve low temperature heating performance. There appears to be an inherent trade-off when operating an unmodified heat pump with mixtures so as to increase capacity at lower temperatures. This trade-off is that as the evaporator pressure decreases and refrigerant begins to flood through to the accumulator and thus allowing the composition shift to occur, the subcooling on the high pressure side also decreases causing a decrease in the available latent enthalpy difference. A possible solution to this problem might be to increase the amount of initial charge. This would cause on increase in head pressures which could be a problem in the cooling mode. A possible solution to this excessive head pressure problem would be to incorporate a receiver in the system in the branch line just ahead of the expansion device for the outdoor coil. Thus, when this coil is acting as an evaporator (i.e., heating mode) the stored refrigerant would be released into the circulating system allowing for more composition shift to occur. Such a solution will be pursued as one of the items of study during the next phase of this project. 9 refs., 11 figs., 1 tab.

Didion, D.; Mulroy, W.

1984-01-01

19

Advanced vapor compression heat pump cycle utilizing non-azeotropic working fluid mixtures  

Microsoft Academic Search

A method of transferring heat from a first fluid having a temperature T⁠to a second fluid having a temperature Tâ, when the temperature Tâ is greater than the temperature T⁠is described comprising: providing a third fluid, comprising a mixture of a higher boiling component and a lower boiling component, having a temperature T\\/sub A\\/, T\\/sub A\\/ being less

Radermacher

1988-01-01

20

Thermodynamic performance limit and evaporator design considerations for NARM-based domestic refrigerator-freeze systems. Rept. for Aug 89-May 90. [Non-Azeotropic Refrigerant Mixtures  

SciTech Connect

The paper gives results of an investigation of non-azeotropic refrigerant mixtures (NARMs) for a two-temperature-level heat exchange process found in a domestic refrigerator-freezer. Ideal (constant air temperature) heat exchange processes are assumed. The results allow the effects of intercooling between the evaporator refrigerant stream and the condenser outlet stream to be examined systematically. Three refrigerant pairs, R22/R142b, R22/R123, and R32/R142b, were studied, but the results for only R22/R123 are presented because of its unique temperature glide curvature. Practical implementation of a Lorenz cycle constrains evaporator design. An evaporator module design is presented which meets the NARM system constraints.

Smith, M.K.; Heun, M.C.; Crawford, R.R.; Newell, T.A.

1990-01-01

21

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

22

Estimation of the entropy of vaporization at the normal boiling point for azeotropic mixtures containing water, alcohol or acetic acid  

Microsoft Academic Search

The entropy of vaporization at the normal boiling point has been estimated for binary and ternary azotropic mixtures containing water, alcohol or acetic acid. For this purpose, the Lee–Kesler correlation, developed originally for pure substances, is used with the appropriate mixing rules to estimate the heat of vaporization of the mixtures. Estimations for the entropy of vaporization of the 97

Ya?ar Demirel

1999-01-01

23

Azeotropic data for binary and ternary systems at moderate pressures  

SciTech Connect

For the synthesis and design of distillation columns the knowledge of azeotropic points is most important. Therefore, a computerized data bank for azeotropic data has been established at the University of Oldenburg to supplement the existing mixture information stored in the Dortmund Data Bank. To check questionable literature data and to extend the contents of the computerized data bank, more than 500 azeotropic and zeotropic data for binary and ternary systems have been measured up to pressures of 3.5 bar with the help of a wire band column. A total of 38 binary azeotropic and zeotropic data for various ethers (MTBE, TAME, TAEE, ETBE, IPTBE) with different alcohols have already been published (Gmehling et al., 1995). A total of 273 binary and 28 ternary azeotropic and zeotropic data are reported in this paper.

Gmehling, J.; Boelts, R. [Univ. Oldenburg (Germany)] [Univ. Oldenburg (Germany)

1996-03-01

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

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

26

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...

27

Potential Energy Savings by Using Alternative Technologies for the Separation of Fluid Mixtures  

E-print Network

) and dehydration. TEXAS AT AUSTIN In the most commonly used pro accomplished by distillation cess both steps (Figure 1) [2J. are The dehydration step is done using an organic entrainer to "break" the azeotrope and allow production of anhydrous ethanol... of ethanol is in the production of gasohol, which is a mixture of gasoline and ethanol. Some processing advantages are present to reduce the energyrequi rements for production of gasohol. Three alternatives appear to offer the best possibilities...

Bravo, J. L.

28

The Influence of Distillation Conditions on the Azeotropic Composition  

NASA Astrophysics Data System (ADS)

The thermodynamic conditions that determine the presence of an azeotrope in a binary solution are developed and analyzed together with the criteria that define if the azeotrope has a maximum or minimum boiling point at constant pressure. It is shown that using simple models for describing vapor-liquid equilibria and vapor pressure data of the pure components it is possible to determine rather accurately how the azeotropic point will shift if the distillation is carried out at a different pressure or temperature. Examples are given on the use of the proposed method; these can be used as classroom material.

Wisniak, Jaime

1998-11-01

29

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

EPA Science Inventory

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

30

Lateral organization of complex lipid mixtures from multiscale modeling  

PubMed Central

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

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

2010-01-01

31

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

32

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...

33

Analysis of Closed Multivessel Batch Distillation of Ternary Azeotropic Mixtures  

E-print Network

. An indirect level control strategy is implemented that eliminates the need for pre-calculated vessel holdups- posed a closed (total reflux) operation of the conventional batch distillation column with a condenser Condenser D Middle 3 2 1 2 1 x + 12B xF 1N N N D x x x x M xM B N Figure 1: Steadystate compositionprofile

Skogestad, Sigurd

34

ATR spectra on boundary with mixture containing organic substances  

NASA Astrophysics Data System (ADS)

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

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

2005-02-01

35

Azeotropic Distillation as a Technique for Emulsion Size Reduction  

E-print Network

: A solvent with HA Boiling point with water Heptane or Hexane Low vapor pressure viscosifying oil Distillation setup/ process -Found the Heterogeneous Azeotropic Distillation Boiling points for Water on microscope - Took several images at different time points - Took pictures in color also to see what was water

Petta, Jason

36

Experimental study of multiple steady states in homogeneous azeotropic distillation  

Microsoft Academic Search

Bekiaris et al. (1993) explained the existence of multiple steady states in homogeneous ternary azeotropic distillation, on the basis of the analysis of the case of infinite reflux and infinite column length (infinite number of trays). They showed that the predictions of multiple steady states for such infinite columns have relevant implications for columns of finite length operated at finite

T. E. Guettinger; Cornelius Dorn; Manfred Morari

1997-01-01

37

How will Primary and Secondary Organic Mixtures Impact CCN?  

NASA Astrophysics Data System (ADS)

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

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

2009-12-01

38

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 ...

39

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...

40

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

41

Control of Meloidogyne incognita Using Mixtures of Organic Acids  

PubMed Central

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

Seo, Yunhee; Kim, Young Ho

2014-01-01

42

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...

43

On protein denaturation in aqueous-organic mixtures but not in pure organic solvents  

SciTech Connect

FTIR spectroscopy was used to quantitatively assess the secondary structure of proteins in aqueous-organic mixtures ranging from pure water to a pure solvent. For every such solution/suspension, the {alpha}-helix content of the protein was independently calculated from the amide I and III spectral regions (which gave essentially identical results). In all cases studied (two unrelated enzymic proteins-lysozyme and subtilisin; three dissimilar water-miscible solvents-acetonitrile, tetrahydrofuran, and 1-propanol), the protein secondary structure was much more native-like in pure organic solvents than in most water-solvent mixtures, e.g., 60% (v/v) organic solvents. In fact, placing lyophilized (or crystalline) proteins in the anhydrous solvents tested had no appreciable effect on the {alpha}-helix content, whereas the latter declined markedly in the 60% (v/v) solvents. This behavior was found to be kinetically controlled, i.e., to be due to inherent restrictions on protein conformational mobility in anhydrous, in contrast to aqueous-organic, media. 34 refs., 3 figs., 2 tabs.

Griebenow, K.; Klibanov, A.M. [Massachusetts Inst. of Technology, Cambridge, MA (United States)] [Massachusetts Inst. of Technology, Cambridge, MA (United States)

1996-11-27

44

Processes of Heat Transfer in Rheologically Unstable Mixtures of Organic Origin  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

45

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

EPA Science Inventory

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

46

Parameters for the Pyrolysis of Organic Material - Perchlorate Mixtures  

NASA Astrophysics Data System (ADS)

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

Steininger, Harald; Goesmann, Fred; Goetz, Walter

2013-04-01

47

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...

48

[Rapid detection of chlorinated organic mixture by laser Raman spectroscopy].  

PubMed

In order to realize the rapid, nondestructive detection of organic compounds, a two-dimensional analysis method based on technology of laser Raman spectroscopy was proposed. The results show that using 532 nm laser as excitation light source, the observation of 236.2, 348.9, 449.4 and 513.6 cm(-1), the four vibrational Raman spectra, and the intensity ratio of 6.4 : 1.7: 9.4 : 1.0 can determine the existence of tetrachloroethylene. The observation of 707.5, 1 087.9, 1 175.8 and 3 078.6 cm(-1), the four vibrational Raman spectra, and the intensity ratio of 9.6 : 6.4 : 1.0 : 3.9 can determine the existence of chlorobenzene. In other words, that through the comprehensive study of spectral lines and intensity ratio of some spectral lines, the presence of organic compounds in the mixed solution can be determined quickly. In the aspect of quantitative analysis, using multi-spectral analysis combined with least square fitting method can improve the reliability of the measurement, The accuracy of sample concentration was 98.4%. This spectral measurement method is a potential tool for organic component identification and concentration analysis which has a prosperous application prospects. PMID:25269297

Ma, Jing

2014-07-01

49

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

50

Interfacial tension of chlorinated aliphatic DNAPL mixtures as a function of organic phase composition.  

PubMed

This research evaluates the ability of three models to predict the organic liquid-water interfacial tension (IFT) of chlorinated aliphatic hydrocarbon mixtures that are dense nonaqueous-phase liquids (DNAPLs). Prediction of the IFT is relevantto quantify processes such as DNAPL trapping in soil pores and kinetic interphase mass transfer. Three models are evaluated: the Fu et al. method (FU) [Fu, J.; Buqiang, L.; Zihao, W. Chem. Eng. Sci. 1986,41 (10), 2673-2679]; a modified version of the Apostoluk and Szymanowski method (AS) [Apostoluk, W.; Szymanowski, J. Solvent Extr. Ion Exch. 1996, 14 (4), 635-651], and a simple linear ideal mixing theory (LIMT). The FU and AS methods require knowledge of NAPL-phase mole fractions and mutual solubilities. The LIMT method requires the pure organic liquid IFT and DNAPL-phase mole fraction as model input. Forty chlorinated DNAPL mixtures were used. The mixtures include two-, three-, and four-component DNAPL mixtures of tetrachloroethylene, trichloroethylene, 1,2-cis-dichloroethylene, 1,2-trans-dichloroethylene, and carbon tetrachloride. Measured IFTvaries nearlylinearlywith DNAPL-phase mole fraction for the all the DNAPL mixtures except those that include 1,2-DCE. The FU and LIMT models generally provided acceptable results for all mixtures. The FU model yielded an average relative error in the predicted IFT of 6.4%, while the LIMT model exhibited an average error of 9.3%. The AS method exhibited an average error of 16.4%. PMID:11944683

Seo, Hyeyoung Sophia; McCray, John E

2002-03-15

51

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

SciTech Connect

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

MARUSICH, R.M.

2006-07-10

52

Liquid-liquid phase separation in atmospheric aerosol particles: dependence on organic functionalities and mixture complexity  

NASA Astrophysics Data System (ADS)

In the troposphere, aerosol particles undergo phase transitions such as deliquescence and efflorescence during humidity cycles (Marcolli and Krieger, 2006). In addition, interactions between organic and inorganic compounds lead to liquid-liquid phase separation (LLPS) (Ciobanu et al., 2009). Recent studies on a limited number of model systems have shown that oxygen-to-carbon ratios (O:C) of the organic aerosol fraction might be a good predictor for LLPS in mixed organic/ammonium sulfate (AS) particles (Bertram et al., 2011; Song et al., 2011). However, in order to corroborate this hypothesis experiments with an organic fraction that consists of a higher number of components with different O:C ratios and functional groups are needed. In order to determine the influence of O:C ratio, the specific organic functionalities and the mixture complexity on LLPS, we subjected organic/AS particles deposited on a hydrophobically coated substrate to relative humidity (RH) cycles and observed phase changes using optical microscopy and micro-Raman spectroscopy. To determine the influence of mixture complexity, we mixed together up to 10 organic compounds. We also prepared mixtures that were rich in different types of functional groups like polyols, aromatics and dicarboxylic acids which were identified from field measurements. We screened for a miscibility gap by varying the organic-to-inorganic ratio from 2:1 to 1:6. AS in the investigated single particles effloresced at 27 - 50 %RH and deliquesced at 72 - 79 %RH during humidity cycles. The occurrence of LLPS is determined to a high degree by the O:C of the organics: there was no LLPS for mixtures with O:C > 0.8 and there was always LLPS for mixtures with O:C < 0.57. In the range in between, we observed a dependence on the specific functional groups: a high share of aromatic functionalities shifts the range of O:C for which LLPS occurs to lower values. A correlation was also found for the onset RH of LLPS as a function of O:C. We did not find any dependence of LLPS on the complexity of the mixture. Overall, the RH range of coexistence of two liquid phases depends in first place on the O:C ratio of the particles and in second place also on the specific organic functionalities.

Song, M.; Marcolli, C.; Krieger, U. K.; Zuend, A.; Peter, T.

2012-04-01

53

The Impact of Organic Aerosol Mixtures on Hygroscopicity: Comparison between Measurements and UNIFAC Model  

NASA Astrophysics Data System (ADS)

The presence of anthropogenic organic compounds in aerosols has the potential to contribute to global climate change by altering the hygroscopic behavior of cloud condensation nuclei. Dicarboxylic acids, including malonic, glutaric, and succinic acids, are among the more frequently measured water-soluble organic compounds in atmospheric aerosols. For solutions containing single or mixed inorganic species, aerosol water uptake has been most commonly modeled using the ZSR method. This approach has also been utilized for solutions containing mixtures of inorganics and organics. For solutions containing a single organic species, the UNIFAC or a modified UNIFAC model has been used, and the features it includes also allow it potentially to be utilized for mixtures. However, there is a dearth of experimental data involving the hygroscopic behavior of organic solution mixtures. In this study, water vapor pressure was measured at 12 C over aqueous bulk solutions containing dicarboxylic acids, using both a quadrupole mass spectrometer and a Baratron pressure transducer. The water uptake of malonic and glutaric acids showed good agreement with limited previous measurements reported in the literature that used an electrodynamic balance (EDB) or bulk solution method. Our experimental measurements of water uptake for malonic and glutaric acids also agreed to within 1% of the predictions using Peng's modified UNIFAC model (Environ. Sci. Technol, 35, 4495-4501, 2001). However, water vapor pressure measurements for solutions containing 50:50 molar mixtures of malonic and glutaric acids were not consistent with predictions using Peng's modified UNIFAC model for mixtures. In the modified UNIFAC model, this mixture of malonic/glutaric acids was predicted to fall roughly midway between the hygroscopicity of the two individual organics. In our measurements, malonic acid exerted the dominant influence in determining the overall water vapor pressure, so that the water uptake of the mixed solution closely followed that of malonic acid. This led to a greater water uptake than what was predicted by the modified UNIFAC model for mixtures. For mixtures of malonic and succinic acids, we added 0.3mol of succinic acid to 1, 3, and 5 mol/l of malonic acid solution. The modified UNIFAC model predicted an additional amount of water uptake due to addition of succinic acid that was essentially the same, regardless of the concentration of malonic acid. However, for our measurements, the influence of the succinic acid on water uptake was negligible for 1 and 3mol/l of malonic acid solutions. In contrast, the 5 mol/l malonic acid solution showed a significant increase in water uptake when 0.3mol of succinic acid was added.

Lee, J.; Hildemann, L.

2011-12-01

54

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

PubMed Central

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

Mazurek, Monica A

2002-01-01

55

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

EPA Science Inventory

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

56

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

57

Thermal Response Of TXV-controlled Heat Pump Systems Operating With Refrigerant Mixtures  

Microsoft Academic Search

Research into the possibility of using azeotropic and nonazeotropic refrigerant mixtures in heat pump systems has gained enormous popularity in the past feu decades. Uhile past studies have investigated the increase in system capacity from using refrigerant blends, these studies have neglected to discuss the problems associated uith metering such mixtures, especially in the case of the nonazeotropic pairs. It

Lawrence R. Grzyll; John J. Silvestri; Isaac Schantz

1990-01-01

58

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

PubMed

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

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

2015-01-14

59

Abatement of mixture of volatile organic compounds (VOCs) in a catalytic non-thermal plasma reactor.  

PubMed

Total oxidation of mixture of dilute volatile organic compounds was carried out in a dielectric barrier discharge reactor with various transition metal oxide catalysts integrated in-plasma. The experimental results indicated the best removal efficiencies in the presence of metal oxide catalysts, especially MnO(x), whose activity was further improved with AgO(x) deposition. It was confirmed water vapor improves the efficiency of the plasma reactor, probably due to the formation of hydroxyl species, whereas, in situ decomposition of ozone on the catalyst surface may lead to nascent oxygen. It may be concluded that non-thermal plasma approach is beneficial for the removal of mixture of volatile organic compounds than individual VOCs, probably due to the formation of reactive intermediates like aldehydes, peroxides, etc. PMID:22975253

Karuppiah, J; Reddy, E Linga; Reddy, P Manoj Kumar; Ramaraju, B; Karvembu, R; Subrahmanyam, Ch

2012-10-30

60

Hydroxyl group determination in high molecular weight alcohols and complex organic mixtures  

Microsoft Academic Search

Acetylation of complex organic mixtures and high mol wt alcohols is inconsistent by existing procedures because of sample\\u000a insolubility. By choosing a suitable mixed paraffin-ethyl acetate solvent to bring about nearly instantaneous solu-tion, and\\u000a utilizing the known catalysis property of perchloric acid, acetylation is quantitative in 10 min or less at room temp. The\\u000a effect of per-chloric acid concn on

D. E. Jordan

1964-01-01

61

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

PubMed

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

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

2008-08-20

62

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

Microsoft Academic Search

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

S. M. Sami

2010-01-01

63

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

SciTech Connect

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

Kujawski, W.

2000-01-01

64

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

65

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

66

Chemical Analysis of Complex Organic Mixtures Using Reactive Nanospray Desorption Electrospray Ionization Mass Spectrometry  

SciTech Connect

Reactive nanospray desorption electrospray ionization (nano-DESI) combined with high-resolution mass spectrometry was utilized for the analysis of secondary organic aerosol produced through ozonolysis of limonene (LSOA). Previous studies showed that LSOA constituents are multifunctional compounds containing aldehyde and ketone groups. In this study, we used the selectivity of the Girard T (GT) reagent towards carbonyl compounds to examine the utility of reactive nano-DESI for the analysis of complex organic mixtures. In these experiments, 1-100 {micro}M GT solution was used as a working solvent for reactive nano-DESI analysis. Abundant products of a single addition of GT to LSOA constituents were observed at GT concentrations in excess of 10 {micro}M. We found that LSOA compounds with 18-20 carbon atoms (dimers) and 27-30 carbon atoms (trimers) react with GT through a simple addition reaction resulting in formation of the carbinolamine derivative. In contrast, reactions of GT with monomeric species result in formation of both the carbinolamine and the hydrazone derivatives. In addition, several monomers did not react with GT on the timescale of our experiment. These molecules were characterized by relatively high values of the double bond equivalent (DBE) and low oxygen content. Furthermore, because addition of a charged GT tag to a neutral molecule eliminates the discrimination against the low proton affinity compounds in the ionization process, reactive nano-DESI analysis enables quantification of individual compounds in the complex mixture. For example, we were able to estimate for the first time the amounts of dimers and trimers in the LSOA mixture. Specifically, we found that the most abundant LSOA dimer was detected at ca. 0.5 pg level and the total amount of dimers and trimers in the analyzed sample was just around 11 pg. Our results indicate that reactive nano-DESI is a valuable approach for examining the presence of specific functional groups and quantification of compounds possessing these groups in complex mixtures.

Laskin, Julia; Eckert, Peter A.; Roach, Patrick J.; Heath, Brandi S.; Nizkorodov, Sergey A.; Laskin, Alexander

2012-08-21

67

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

EPA Science Inventory

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

68

Mixture effects on horizontal convective boiling heat transfer  

Microsoft Academic Search

Mixture effects were studied in horizontal convective heat transfer for both nonazeotropic, R22\\/R114, and azeotropic, R12\\/R152a, mixtures. A test facility was designed, constructed, and operated to simulate evaporators in heat pump and refrigeration systems. More than 3000 local two-phase heat transfer coefficients were obtained under steady state condition for annular flow at a reduced pressure of 0.08. The ranges of

1988-01-01

69

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

70

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

PubMed

Despite the relevance of resting eggs for ecology and evolution of many aquatic organisms and their exposure to contaminants accumulating in sediments, ecotoxicological studies using resting eggs are vastly underrepresented. The authors established a method to perform exposure assays with resting eggs produced by the Daphnia longispina species complex, key species in large lake ecosystems. A mixture of organic contaminants previously detected in sediments of Lake Greifensee was selected to test the potential effect of organic contaminants present in sediments on the hatching process. Resting eggs were exposed to a mix of 10 chemicals, which included corrosion inhibitors, biocides, pesticides, and personal care products, for a period of 15?d. Using an automated counting software, the authors found a significant increase in hatching success in the exposed resting eggs compared with controls. Such an effect has not yet been reported from ecotoxicological assays with resting eggs. Possible mechanistic explanations as well as the potential implications on the ecology and evolution of aquatic species that rely on a resting egg banks are discussed. Observed increased mortality and developmental abnormalities for hatchlings in the exposure treatments can be explained by toxic contaminant concentrations. The results of the present study highlight the need for additional studies assessing the effects of organic contaminants on resting egg banks and aquatic ecosystems. Environ Toxicol Chem 2014;9999:1-8. © 2014 SETAC. PMID:25394187

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

2015-02-01

71

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

PubMed

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

Lugemwa, Fulgentius N

2012-01-01

72

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

73

Synergistic Disruption of External Male Sex Organ Development by a Mixture of Four Antiandrogens  

PubMed Central

Background By disrupting the action of androgens during gestation, certain chemicals present in food, consumer products, and the environment can induce irreversible demasculinization and malformations of sex organs among male offspring. However, the consequences of simultaneous exposure to such chemicals are not well described, especially when they exert their actions by differing molecular mechanisms. Objectives To fill this gap, we investigated the effects of mixtures of a widely used plasticizer, di(2-ethylhexyl) phthalate (DEHP); two fungicides present in food, vinclozolin and prochloraz; and a pharmaceutical, finasteride, on landmarks of male sexual development in the rat, including changes in anogenital distance (AGD), retained nipples, sex organ weights, and malformations of genitalia. These chemicals were chosen because they disrupt androgen action with differing mechanisms of action. Results Strikingly, the effect of combined exposure to the selected chemicals on malformations of external sex organs was synergistic, and the observed responses were greater than would be predicted from the toxicities of the individual chemicals. In relation to other hallmarks of disrupted male sexual development, including changes in AGD, retained nipples, and sex organ weights, the combined effects were dose additive. When the four chemicals were combined at doses equal to no observed adverse effect levels estimated for nipple retention, significant reductions in AGD were observed in male offspring. Conclusions Because unhindered androgen action is essential for human male development in fetal life, these findings are highly relevant to human risk assessment. Evaluations that ignore the possibility of combination effects may lead to considerable underestimations of risks associated with exposures to chemicals that disrupt male sexual differentiation. PMID:20049201

Christiansen, Sofie; Scholze, Martin; Dalgaard, Majken; Vinggaard, Anne Marie; Axelstad, Marta; Kortenkamp, Andreas; Hass, Ulla

2009-01-01

74

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

PubMed

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

Adam, Thomas; Zimmermann, Ralf

2007-11-01

75

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

PubMed

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

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

2003-08-20

76

A neurological evaluation of workers exposed to mixtures of organic solvents.  

PubMed Central

Workers with long term exposure to mixtures of organic solvents below regulatory limits have been reported to experience mild, but clinically detectable, sensory or sensorimotor polyneuropathies. In conjuction with a cross sectional study of behavioural performance a clinical neurological evaluation was conducted among printers and spray painters to examine dose response relations. All 240 subjects completed an occupational history and symptom questionnaire and underwent a clinical neurological examination. On average, subjects had been employed on their current job for six years. Classification of solvent exposure for each subject was based on exposed versus non-exposed job titles and observations during an industrial hygiene walk-through or on the measured concentration of solvents in full shift personal air samples. The average full shift solvent concentration was 302 ppm for printing plant workers and 6-13 ppm for workers at other plants. Isopropanol and hexane were the major constituents. Neurological abnormalities consistent with mild polyneuropathy were found in 16% of subjects; none was clinically significant. Exposed/non-exposed comparisons showed slightly higher frequency of symptoms in the exposed subjects which was not related to solvent level. Subjects categorised as exposed during the walk- through survey also had poorer vibratory sensation measured at the foot and diminished ankle reflexes. In multiple linear regression models, however, controlling for age, sex, alcohol intake, and examiner, no significant (p less than 0.05) relation was found between solvent concentration and poor neurological function except for two point discrimination measured at the foot. This investigation has not provided evidence for dose related adverse neurological effects from exposure to moderately low levels of solvent mixtures for a relatively short duration, although this may be due to the shortness of exposure duration, the type of solvent exposure, or to selection factors. PMID:3814530

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

1987-01-01

77

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...

78

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...

79

Alterations in lung function due to mixtures of organic solvents used in floor laying.  

PubMed

To determine the short-term and long-term effects of organic solvents on the respiratory tract, 26 male floorlayers exposed to organic solvents were compared with 36 persons unexposed to such substances. The investigation primarily included a detailed history, determination of solvent concentration in the air inhaled by the workers, long-term ECG during the entire shift and lung-function test (vital capacity, forced expiratory volume in one second, flow volume curve) as well as non-specific bronchial inhalation challenge using a 3% acetylcholine aerosol before and after the shift. The floorlayers were primarily subjected to inhalative exposure to adhesives containing mixtures of toluene, petroleum hydrocarbons, ethyl acetate, methanol and acetone or one of these substances alone. This frequently resulted in short-term value limit excesses, especially in the MAK value (standardised threshold concentration in Germany) for toluene, which is a prime component of neoprene glue. Of the 26 floorlayers, 6 complained of breathlessness and coughing, whereas 13 suffered from nasal discharge and blockage--symptoms closely related to work. The smokers in this group showed a decline in lung function during the shift--especially in the forced expiratory volume in 1 s (FEV1)--as compared with the non-smokers in this group and the persons in the control group. This probably due to the combination of noxious substances. A strong correlation between occupational age and changes in lung function was observed: the occupationally youngest workers demonstrated the highest decrease in values during the course of the shift. There was no evidence of either obstructive or restrictive respiratory disorders or of marked deviation from the European Community for Coal and Steel (ECCS) references.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1856023

Angerer, P; Marstaller, H; Bahemann-Hoffmeister, A; Römmelt, H; Höppe, P; Kessel, R

1991-01-01

80

Energy efficient membrane processes for the separation of organic liquids: Part 1: Final report, September 28, 1982--December 31, 1986  

SciTech Connect

The potential usefulness of two membrane processes, namely, pervaporation and perstraction, for separating azeotropic mixtures of aromatic and aliphatic hydrocarbons was studied theoretically and experimentally. A third membrane process, osmotic phase-separation, was investigated experimentally. The separation of an azeotropic mixture of benzene and cyclohexane was used as an example. Part II of this report will discuss membrane processes for the separation of alcohol/water mixtures. Mathematical models of pervaporation and perstraction were developed for computer simulations of the processes. The perstraction model presented herein is the first of its kind. Additionally, the energy requirements and capital investments costs for the separation of an azeotropic benzene/cyclohexane mixture were determined and compared with those for extractive distillation. 31 refs., 64 figs., 19 tabs.

Cabasso, I.; Acharya, H.R.; Korngold, E.; Liu, Z.; Stern, S.A.; Li, W.; Makenzie, T.; Poda, E.

1987-10-01

81

A reactive distillation process for a cascade and azeotropic reaction system: Carbonylation of ethanol with dimethyl carbonate  

Microsoft Academic Search

Modelling and simulation of the reactive distillation column have been carried out for the carbonylation process of ethanol with dimethyl carbonate (DMC) producing diethyl carbonate (DEC). As it includes three azeotropes and two cascade reversible reactions with an undesired intermediate, methyl-and-ethyl carbonate (MEC), the reactive distillation is ideally appropriate. Calculations via a robust transient method reveal that a complete DMC

Hu-Ping Luo; Wen-De Xiao

2001-01-01

82

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

83

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

EPA Science Inventory

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

84

Toxicity to Eisenia andrei and Folsomia candida of a metal mixture applied to soil directly or via an organic matrix.  

PubMed

Regulatory limits for chemicals and ecological risk assessment are usually based on the effects of single compounds, not taking into account mixture effects. The ecotoxicity of metal-contaminated sludge may, however, not only be due to its metal content. Both the sludge matrix and the presence of other toxicants may mitigate or promote metal toxicity. To test this assumption, the toxicity of soils recently amended with an industrial sludge predominantly contaminated with chromium, copper, nickel, and zinc and soils freshly spiked with the same mixture of metals was evaluated through earthworm (Eisenia andrei) and collembolan (Folsomia candida) reproduction tests. The sludge was less toxic than the spiked metal mixture for E. andrei but more toxic for F. candida. Results obtained for the earthworms suggest a decrease in metal bioavailability promoted by the high organic matter content of the sludge. The higher toxicity of the sludge for F. candida was probably due to the additive toxic effect of other pollutants. PMID:21683441

Natal-da-Luz, T; Ojeda, G; Pratas, J; Van Gestel, C A M; Sousa, J P

2011-09-01

85

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

PubMed

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

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

2014-11-18

86

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

PubMed

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

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

2014-11-01

87

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

PubMed

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

Uragami, Tadashi; Saito, Tomoyuki; Miyata, Takashi

2015-04-20

88

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

Microsoft Academic Search

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

Ismail Kul; Darryl D DesMarteau; Adolph L Beyerlein

2000-01-01

89

Adsorption and separation of binary mixtures in a metal-organic framework Cu-BTC: A computational study  

Microsoft Academic Search

Grand canonical Monte Carlo simulations were conducted to systematically evaluate the adsorption separation of three binary mixtures, CO2\\/CO, C2H4\\/CO2, and C2H4\\/C2H6, in a metal-organic framework Cu-BTC at room temperature. The simulated results showed that Cu-BTC could be potentially used for the purification of carbon monoxide, capture of carbon dioxide and separation of olefin\\/paraffin. The topology structure of the side pockets

Sanyue Wang; Qingyuan Yang; Chongli Zhong

2008-01-01

90

Nanostructural organization in carbon disulfide\\/ionic liquid mixtures: Molecular dynamics simulations and optical Kerr effect spectroscopy  

Microsoft Academic Search

In this paper, the nanostructural organization and subpicosecond intermolecular dynamics in the mixtures of CS2 and the room temperature ionic liquid (IL) 1-pentyl-3-methylimidazolium bis{(trifluoromethane)sulfonyl}amide ([C5mim][NTf2]) were studied as a function of concentration using molecular dynamics (MD) simulations and optical heterodyne-detected Raman-induced Kerr effect spectroscopy. At low CS2 concentrations (=10 mol.% CS2\\/IL), the MD simulations show aggregation of the CS2 molecules.

Peng Yang; Gregory A. Voth; Dong Xiao; Larry G. Hines; Richard A. Bartsch; Edward L. Quitevis

2011-01-01

91

Nanostructural organization in carbon disulfide?ionic liquid mixtures: Molecular dynamics simulations and optical Kerr effect spectroscopy  

Microsoft Academic Search

In this paper, the nanostructural organization and subpicosecond intermolecular dynamics in the mixtures of CS2 and the room temperature ionic liquid (IL) 1-pentyl-3-methylimidazolium bis{(trifluoromethane)sulfonyl}amide ([C5mim][NTf2]) were studied as a function of concentration using molecular dynamics (MD) simulations and optical heterodyne-detected Raman-induced Kerr effect spectroscopy. At low CS2 concentrations (<10 mol.% CS2?IL), the MD simulations indicate that the CS2 molecules are

Peng Yang; Gregory A. Voth; Dong Xiao; Larry G. Hines Jr; Richard A. Bartsch; Edward L. Quitevis

2011-01-01

92

Microbial degradation kinetics of volatile organic compound mixtures in a biofilter.  

E-print Network

??Biofiltration degradation kinetics of an aldehyde mixture containing hexanal, 2-methylbutanal, and 3-methylbutanal was investigated using a bench-scale, synthetic medium based biofilter. The adsorption capacity of… (more)

Wang, Li

2006-01-01

93

Suppression of sourness: A comparative study involving mixtures of organic acids and sugars  

Microsoft Academic Search

The degree of sourness suppression of perceptually equisour levels of citric, lactic, and malic acids by equal molar and weight\\u000a amounts of sucrose, fructose, and glucose was determined in binary mixtures. Equisour acid levels were obtained by magnitude\\u000a estimation. Mixture intensity ratings were collected on a categorical scale, using trained panelists. In general, equal sugar\\u000a molarities and weights did not

Lotika Savant; Mina R. McDaniel

2004-01-01

94

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

95

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

SciTech Connect

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

Charles J Werth; Albert J Valocchi, Hongkyu Yoon

2011-05-21

96

Vapor–liquid equilibria for binary and ternary mixtures of ethanol, 2-butanone, and 2,2,4-trimethylpentane at 101.3 kPa  

Microsoft Academic Search

Vapor–liquid equilibrium (VLE) at 101.3kPa have been determined for the ternary system ethanol+2-butanone+2,2,4-trimethylpentane (isooctane) and its constituent binary systems: ethanol+2,2,4-trimethylpentane, ethanol+2-butanone, and 2-butanone+2,2,4-trimethylpentane. Minimum boiling azeotropes were observed for all these binary systems. No azeotropic behavior was found for the ternary system. Thermodynamic consistency tests were performed for all VLE data. The activity coefficients of the binary mixtures were satisfactorily

Chao-Cheng Wen; Chein-Hsiun Tu

2007-01-01

97

(Vapour + liquid) equilibria for binary and ternary mixtures of 2-propanol, tetrahydropyran, and 2,2,4-trimethylpentane at P = 101.3 kPa  

Microsoft Academic Search

(Vapour+liquid) equilibrium (VLE) at P=101.3kPa have been determined for a ternary system (2-propanol+tetrahydropyran+2,2,4-trimethylpentane) and its constituent binary systems (2-propanol+tetrahydropyran, 2-propanol+2,2,4-trimethylpentane), and (tetrahydropyran+2,2,4-trimethylpentane). Analysis of VLE data reveals that two binary systems (2-propanol+tetrahydropyran) and (2-propanol+2,2,4-trimethylpentane) have a minimum boiling azeotrope. No azeotrope was found for the ternary system. The activity coefficients of liquid mixtures were obtained from the modified Raoult’s law

Dun-Yi Lin; Chein-Hsiun Tu

98

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

Microsoft Academic Search

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

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

2011-01-01

99

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

EPA Science Inventory

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

100

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

E-print Network

Received in revised form 2 May 2011 Accepted 3 May 2011 Keywords: Indoor chemistry Ozone D-limonene a reactions with both single terpenoids and mixtures of D-limonene, a-pinene, and a-terpineol. Transient concentration conditions, reactions with only D-limonene yielded the largest number concentrations of any

Siegel, Jeffrey

101

Newly developed ceramic membranes for dehydration and separation of organic mixtures by pervaporation  

Microsoft Academic Search

Polymeric pervaporation membranes sometimes show great variety in performance when they are alternately used for different solvent mixtures. In addition, membrane stability in time is a problem in case of some solvents. Therefore, newly developed ceramic silica membranes with a “dense” top layer were tested for pervaporation. In dehydration of the lower alcohols methanol, ethanol and 2-propanol selectivities of 400,

Robert W. van Gemert; F. Petrus Cuperus

1995-01-01

102

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 ...

103

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...

104

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

PubMed Central

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

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

2014-01-01

105

Mechanisms of action of two different natural mixtures of persistent organic pollutants (POPs) in ovarian follicles.  

PubMed

The present work investigated the effects of two different natural mixtures on aryl hydrocarbon receptor (AhR) and oestrogen receptor (ER)beta protein levels, as well as on the activity of cytochrome P450 (CYP) 1A1 and CYP2B. Consequently, the authors observed the effects of these mixtures on gonadotropine-stimulated steroid secretion by ovarian follicles. The natural mixtures that were studied were 'Mjosa' extracted from burbot liver, which contains a high level of PBDEs, and 'Marine mix', extracted from Atlantic cod liver, which contains a high level of polychlorinated biphenyls (PCBs). Follicular cells were exposed in vitro to 'Marine mix' and 'Mjosa mix' at doses of 3.6 and 1.4 microg ml(-1), respectively. Media were collected and used for steroid analysis and cell viability assays. Cells were used to estimate aromatase activity (CYP19), AhR and ER protein levels, and CYP1A1 and CYP2B1 activity. Western blot analysis indicated down-regulation of AhR by 'Marine mix' and down-regulation of ERbeta by Mjosa mix. Up-regulation of CYP1A1 expression and activity were seen following treatment with Marine mix, but not Mjosa mix. Increased CYP2B1 activity was noted after treatment with both 'Marine mix' and Mjosa mix. Both mixtures increased luteinizing hormone (LH)-stimulated progesterone and testosterone secretion, follicle-stimulating hormone (FSH)-stimulated oestradiol secretion, and CYP19 activity. These results suggest that: (1) 'Marine mix' is a mixed-type CYP inducer; (2) 'Mjosa mix' is an inducer of ERbeta and CYP2B; and (3) both 'Marine mix' and 'Mjosa mix' stimulate aromatase activity as a consequence of oestradiol secretion through activation of CYP19. PMID:19219750

Gregoraszczuk, E L; Ptak, A; Skaare, J U; Mularz, K; Chmielowiec, A; Wojtowicz, A; Ropstad, E

2009-01-01

106

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

107

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

PubMed

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

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

2011-05-01

108

Correlation between free-volume properties and pervaporative flux of polyurethane-zeolite composites on organic solvent mixtures.  

PubMed

Micron-sized zeolite particles were incorporated into a polyurethane (PU) matrix to prepare ethylbenzene-selective membranes. The resulting composite membranes were used in the pervaporation (PV) of ethylbenzene/styrene (EB/ST) mixtures. The sorption, diffusion, and PV permeation behaviors as a result of zeolite addition were elucidated. Zeolite is less chemically compatible with organic solvents than PU and the PU-zeolite composites, which exhibited suppressed solvent solubilities compared with pristine PU. However, these membranes favor EB transport by diffusion selectivity. The diffusivity and permeation flux increases in parallel with the enlarged radius of the free-volume hole size (R(4) increasing from 3.46 to 3.64 Å using positron annihilation lifetime spectroscopy analysis) by increasing the zeolite content from 0 to 23%. The enlarged free volume at a zeolite loading of 23% promoted pure solvent diffusivities by 10% higher than that of the unfilled film. During the PV operation on the EB/ST mixture, a significant diffusion-coupling was observed, and the permeant diffusion coefficients from the binary mixture exceeded the pure solvent diffusivity. The permeation flux was greatly improved (up to 0.72 kg/m(2)·h) by zeolite addition without any detrimental effect on the separation efficiency. PMID:21375225

Lue, Shingjiang Jessie; Su, I-Ming; Lee, Da-Tung; Chen, Hsin-Yi; Shih, Chao-Ming; Hu, Chien-Chieh; Jean, Y C; Lai, Juin-Yih

2011-03-31

109

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

PubMed

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

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

2014-05-01

110

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

PubMed Central

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

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

2012-01-01

111

Photonic crystal based sensor for organic solvents and for solvent-water mixtures.  

PubMed

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

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

2012-01-01

112

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-...

113

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-...

114

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

DOEpatents

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

Pekala, R.W.

1998-04-28

115

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

DOEpatents

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

Pekala, Richard W. (Pleasant Hill, CA)

1995-01-01

116

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

DOEpatents

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

Pekala, Richard W. (Pleasant Hill, CA)

1996-01-01

117

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

DOEpatents

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

Pekala, R.W.

1995-12-19

118

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

DOEpatents

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

Pekala, Richard W. (Pleasant Hill, CA)

1998-04-28

119

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

DOEpatents

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

Pekala, R.W.

1996-09-17

120

Higher-Order Mass Defect Analysis for Mass Spectra of Complex Organic Mixtures  

SciTech Connect

Higher-order mass defect analysis is introduced as a unique formula assignment and visualization method for the analysis of complex mass spectra. This approach is an extension of the concepts of Kendrick mass transformation widely used for identification of homologous compounds differing only by a number of base units (e.g., CH2, H2, O, CH2O, etc.) in complex mixtures. We present an iterative renormalization routine for defining higher order homologous series and multidimensional clustering of mass spectral features. This approach greatly simplifies visualization of complex mass spectra and increases the number of chemical formulae that can be confidently assigned for given mass accuracy. The potential for using higher-order mass defects for data reduction and visualization is shown. Higher-order mass defect analysis is described and demonstrated through third-order analysis of a de-isotoped high-resolution mass spectrum of crude oil containing nearly 13,000 peaks.

Roach, Patrick J.; Laskin, Julia; Laskin, Alexander

2011-06-15

121

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

122

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

EPA Science Inventory

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

123

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

EPA Science Inventory

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

124

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

NASA Technical Reports Server (NTRS)

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

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

1968-01-01

125

Nanostructural organization in carbon disulfide?ionic liquid mixtures: molecular dynamics simulations and optical Kerr effect spectroscopy.  

PubMed

In this paper, the nanostructural organization and subpicosecond intermolecular dynamics in the mixtures of CS(2) and the room temperature ionic liquid (IL) 1-pentyl-3-methylimidazolium bis{(trifluoromethane)sulfonyl}amide ([C(5)mim][NTf(2)]) were studied as a function of concentration using molecular dynamics (MD) simulations and optical heterodyne-detected Raman-induced Kerr effect spectroscopy. At low CS(2) concentrations (<10 mol.% CS(2)/IL), the MD simulations indicate that the CS(2) molecules are localized in the nonpolar domains. In contrast, at higher concentrations (?10 mol.% CS(2)/IL), the MD simulations show aggregation of the CS(2) molecules. The optical Kerr effect (OKE) spectra of the mixtures are interpreted in terms of an additivity model with the components arising from the subpicosecond dynamics of CS(2) and the IL. Comparison of the CS(2)-component with the OKE spectra of CS(2) in alkane solvents is consistent with CS(2) mainly being localized in the nonpolar domains, even at high CS(2) concentrations, and the local CS(2) concentration being higher than the bulk CS(2) concentration. PMID:21787008

Yang, Peng; Voth, Gregory A; Xiao, Dong; Hines, Larry G; Bartsch, Richard A; Quitevis, Edward L

2011-07-21

126

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

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

127

Linear-to-Volcanic Response in a Self-Organizing Driven Fluid Mixture by an Interacting Lattice Gas Computer Simulation  

NASA Astrophysics Data System (ADS)

A computer simulation model is used to study the transport, flow, and self-organizing morphology in a multi-component fluid mixture. We consider a mixture of two immiscible components (A, B) driven by a hydrostatic pressure bias from a source (reservoir) at the bottom on a cubic lattice. Mobile particles (A, B - representing heavier gas hydrate/sediment particles and fluid) in equal number are distributed randomly on half of the lattice sites initially where a site cannot be occupied by more than one particle. The empty (pore) sites can act as a component of an effective medium. A set of interactions among these constituents is considered in addition to excluded volume hard-core interaction. The hydrostatic pressure bias (H) is implemented probabilistically to drive particles (A, B) against gravity. We use the Metropolis algorithm to move these particles stochastically. Periodic boundary conditions are used along the transverse directions while the longitudinal ends (top and bottom) are open. Thus, particles can escape from the top or bottom; however, they can enter the lattice only from the source at the bottom in this model. The probability of release of constituents (A, B) depend on their current relative concentrations in the lattice. Particles flow, re-distribute, and their concentrations change as the simulation proceeds. The flux rate of particle flow becomes constant and the morphology become stable in the long time steady-state limit. We observe a variety of self-organized structures, which exhibit dense phase at the bottom and dilute (gaseous) phase on the top with a bi-continuous phase in between. The flux rate (j) shows linear response at low hydrostatic bias but is different for constituents (A, B) with different molecular weight. The response becomes non-linear in high-bias regime; there it diverges (essentially erupts) for higher molecular weight components while it decreases for the lighter component.

Pandey, R. B.; Gettrust, J. F.

2005-05-01

128

Interactions of Pb and Cd mixtures in the presence or absence of natural organic matter with the fish gill.  

PubMed

Metal gill binding and toxicity can be modeled using the concentration addition model, in which the toxic unit (TU) concept is used to determine if constituent metals are acting in a strictly additive, less than, or greater than additive fashion. To test this hypothesis, rainbow trout (Oncorhynchus mykiss) were exposed to a matrix of Pb plus Cd mixtures (nominal concentrations=0.75, 1.5, 2.25, 3.0 ?mol L(-1)), in the presence or absence of mainly terrigenous (allochthonous; 10 mg CL(-1)) natural organic matter (NOM), and metal-gill binding, and toxicity was quantified. Based on its greater affinity for metal-gill binding sites, Cd-gill binding was expected to exceed Pb-gill binding during metal mixture exposure, but this only occurred at the lowest metal concentrations (0.75 ?mol L(-1)); at higher concentrations Pb-gill binding was greater than Cd-gill binding. These unexpected observations were because Pb and Cd likely bind to different populations of high affinity, low capacity binding sites on the gill, which was borne out in subsequent attempts to mathematically model metal-gill interactions during metal-mixture exposure. The presence of an additional low affinity, high capacity population of Pb-gill binding sites also contributed to higher Pb-gill accumulation. Metal-gill interactions were complicated by NOM, which exacerbated toxicity during Cd-only exposure despite lowering Cd-gill accumulation. NOM also promoted Cd-gill binding in the presence of low-moderate concentrations of Pb (0.75 and 1.50 ?mol L(-1)). We suggest that direct interactions of Cd-NOM complexes with the gill, and increases in Cd bioavailability due to Pb outcompeting Cd for NOM-metal binding sites due to its greater affinity for such ligands, accounted for greater Cd-gill binding and toxicity. We conclude that interactions of Pb and Cd with the gill cannot be predicted using the concentration addition model, and that NOM is not universally protective against metal-gill binding and toxicity when fish are exposed to metal mixtures. PMID:22749195

Winter, Anna R; Playle, Richard C; George Dixon, D; Borgmann, Uwe; Wilkie, Michael P

2012-09-01

129

Dehydration of water-pyridine mixtures by pervaporation  

SciTech Connect

The pervaporation technique, in which the liquid feed mixture is maintained in contact with one side of a nonporous membrane and the permeate is continuously removed from the other side as a vapor, is one of the new methods to attain separation of azeotropic mixtures, structural isomers, or even to displace the equilibrium of chemical reactions. Several ion-exchange and neutral membranes were examined in the pervaporation of water-pyridine mixtures. Carboxylic and sulfonic ion-exchange membranes were used with hydrogen counterion and additionally with trimethylammonium, triethylammonium, and tributylammonium counterions. All membranes were selective to water, but the transport mode and selectivity properties of membranes were dependent on both the character of the ion-exchange group and the ionic form of the membrane. The results obtained suggest that pervaporation of water-pyridine mixtures could be used with standard distillation in the large-scale dehydration process of pyridine.

Kujawski, W. (N. Copernicus Univ., Torun (Poland) Centre National de la Recherche Scientifique-UA 494, Nancy (France)); Nguyen, T.Q.; Neel, J. (Centre National de la Recherche Scientifique-UA 494, Nancy (France))

1991-08-01

130

Adsorption of ethoxylated styrene oxide and polyacrylic acid and mixtures there of on organic pigment.  

PubMed

The adsorption of two polymeric surfactants on an organic pigment was investigated. As surfactants the anionic polyacrylic acid sodium salt (PANa, M(W)=15,000) and a non-ionic block copolymer surfactant based on styrene oxide (SO) and ethylene oxide (EO) (M(W)=1500) were used. The adsorption behavior was analyzed by size exclusion chromatography of the supernatant after centrifugation of the pigment dispersions. It was found that PANa has no affinity to the pigment, whereas SO-EO has a strong affinity to the pigment surface. Competitive adsorption of PANa and SO-EO was not observed. Addition of SO-EO yields stable dispersions. PMID:18771776

Wijting, W K; Laven, J; van Benthem, R A T M; de With, G

2008-11-01

131

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

SciTech Connect

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

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

1999-02-12

132

Mixture effects on horizontal convective boiling heat transfer  

SciTech Connect

Mixture effects were studied in horizontal convective heat transfer for both nonazeotropic, R22/R114, and azeotropic, R12/R152a, mixtures. A test facility was designed, constructed, and operated to simulate evaporators in heat pump and refrigeration systems. More than 3000 local two-phase heat transfer coefficients were obtained under steady state condition for annular flow at a reduced pressure of 0.08. The ranges of heat flux and mass flow rates were 10-45 kW/m{sup 2} and 16-46 g/s, equivalent to 250-720 kg/m{sup 2} s. The overall compositions of mixtures were 0, 23, 47, 77, and 100% R22 by mole for R22/R114 mixtures and 0, 21, 60 (Azeotrope), 89, and 100% R12 by mole for R12/R152a mixtures. The results indicated that there were two distinct heat transfer regions; partial boiling and convective evaporation. For a given heat and mass flux, nucleate boiling was suppressed at lower qualities for mixtures than for pure fluids. The unique phenomenon of loss of available superheat for mixtures caused nucleate boiling to be suppressed at lower qualities. An analytical study was performed to predict the transition quality by utilizing a theory of onset of nucleate boiling and phase equilibrium data. Local heat transfer coefficients for mixtures were as much as 36% lower than a weighted average of the pure components values in the convective region. The non-ideal variation of physical properties accounted for most of the heat transfer degradation.

Jung, D.

1988-01-01

133

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

Microsoft Academic Search

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

D. T. Chen; J. C. Conklin

1999-01-01

134

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

Microsoft Academic Search

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

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

1992-01-01

135

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

Microsoft Academic Search

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

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

1991-01-01

136

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

137

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

PubMed

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

Shekaari, Hemayat; Kazempour, Amir; Khoshalhan, Maryam

2015-01-21

138

A Bayesian mixture model relating dose to critical organs and functional complication in 3D conformal radiation therapy.  

PubMed

A goal of cancer radiation therapy is to deliver maximum dose to the target tumor while minimizing complications due to irradiation of critical organs. Technological advances in 3D conformal radiation therapy has allowed great strides in realizing this goal; however, complications may still arise. Critical organs may be adjacent to tumors or in the path of the radiation beam. Several mathematical models have been proposed that describe the relationship between dose and observed functional complication; however, only a few published studies have successfully fit these models to data using modern statistical methods which make efficient use of the data. One complication following radiation therapy of head and neck cancers is the patient's inability to produce saliva. Xerostomia (dry mouth) leads to high susceptibility to oral infection and dental caries and is, in general, unpleasant and an annoyance. We present a dose-damage-injury model that subsumes any of the various mathematical models relating dose to damage. The model is a nonlinear, longitudinal mixed effects model where the outcome (saliva flow rate) is modeled as a mixture of a Dirac measure at zero and a gamma distribution whose mean is a function of time and dose. Bayesian methods are used to estimate the relationship between dose delivered to the parotid glands and the observational outcome-saliva flow rate. A summary measure of the dose-damage relationship is modeled and assessed by a Bayesian chi(2) test for goodness-of-fit. PMID:15917377

Johnson, Timothy D; Taylor, Jeremy M G; Ten Haken, Randall K; Eisbruch, Avraham

2005-10-01

139

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

140

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

141

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

PubMed

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

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

2011-01-01

142

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

143

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

PubMed

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. PMID:18647030

Warshavsky, Vadim B; Song, Xueyu

2008-07-21

144

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

PubMed

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

Pena-Pereira, Francisco; Namie?nik, Jacek

2014-07-01

145

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

146

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...

147

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

SciTech Connect

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

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

2014-03-28

148

Thermodynamic and kinetic control of charged, amphiphilic triblock copolymer assembly via interaction with organic counterions in solvent mixtures  

NASA Astrophysics Data System (ADS)

Amphiphilic block copolymers, consisting of at least two types of monomers with different affinity to the dissolving solvent(s), have been recognized as a molecular building unit for their chemical tunability and design flexibility. Amphiphilic block copolymers with a chargeable block have structural features of polyelectrolytes, block copolymers and surfactants. The combination of these different features offers great flexibility for developing novel assembled morphologies at the nanoscale and outstanding ability to control and manipulate those morphologies. The nanostructures, formed from the spontaneous association of amphiphilic block copolymer in selective solvents, show promise for applications in nanotechnology and pharmaceuticals, including drug delivery, tissue engineering and bio-imaging. A basic knowledge of their modes of self-assembly and their correspondence to application-related properties is just now being developed and poses a considerable scientific challenge. The goal of this dissertation is to investigate the associative behavior of charged, amphiphilic block copolymers in solvent mixtures while in the presence of organic counterions. Self-assembly of poly (acrylic acid)- block-poly (methyl acrylate)-block-polystyrene (PAA- b-PMA-b-PS) triblock copolymers produces nanodomains in THF/water solution specifically through the interaction with organic counterions (polyamines). These assembled structures can include classic micelles (spheres, cylinders and vesicles), but, more importantly, include non-classic micelles (disks, toroids, branched micelles and segmented micelles). Each micelle structure is stable and reproducible at different assembly conditions. The assembled micellar structures depend on not only solution components (thermodynamics) but also mixing procedure and consequent self-assembly pathway (kinetics). The key factors that determine the thermodynamic interactions that partially define the assembled structures and the kinetic assembly process include THF/water ratio, PS block length, the type and amount of organic counterions, and the mixing pathway. Their formation mechanism has been investigated from three aspects: (i) the chain structure of organic counterions, including spacer length, chain hydrophobicity between ionizable groups and the number of ionizable groups (amine group); (ii) molecular structure of the triblock copolymer, including block length of polystyrene and chain architecture; (iii) relative variation of the components, such as different ratios of THF to water and the different ratios of amine groups to acid groups. The first example of a novel micelle formed was the toroidal micelle. The toroidal micelle morphology, which is theoretically predicted but rarely observed, has been produced by the self assembly of PAA99- b-PMA73-b-PS66 in combination with 2,2-(ethylenedioxy)diethylamine (EDDA) and mixed THF/H2O solvent. It was found that toroids can be constructed by two mechanisms: elimination of energetically unfavored cylindrical micelle endcaps or perforation of disk-like micelles. Three-fold junctions were formed as intermediate structures to facilitate toroidal formation from cylindrical micelles. In order to construct toroids from cylindrical micelles, three requirements must be met: lower bending modulus (flexibility of cylinders), selfattraction between cylinders, and extra endcapping energy originating from chain packing frustration. Extremely high energy spheres can also fuse into toroids. Disk-like micelles can transform into a toroidal morphology when cylindrical packing geometry was initiated along the rims of disk-like micelles via solvent mixing that eventually perforated the disk center. The toroidal morphology can be kinetically trapped by either ridding the system of organic solvent or chemically crosslinking the PAA corona with EDDA via addition of 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide methiodide (DPEM). The interaction of positively-charged, multivalent organic amines with the negatively-charged PAA corona plays a decisive role in the formatio

Cui, Honggang

2007-12-01

149

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

PubMed

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

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

2012-07-15

150

Energy efficient membrane processes for the separation of organic liquids: Part 3 (Supplement report): Final report, September 28, 1982--December 31, 1986  

SciTech Connect

In this supplemental report, two pilot plants are described. The first is air purge pervaporation (or air sweep pervaporation hollow fiber system) for the separation of azeotropic aqueous liquids. The second describes pilot plant construction and operation for the perstraction process. Several configurations for the air purge pervaporation process were studied and were shown to yield high purity products e.g., isopropanol from the azeotropic mixture with water was enriched to 99.9%. Parallel and U-module configuration were used and durability experiments up to 120 days were carried out successfully. The report describes the first successful low scale pilot plant unit and elements for perstraction process. The conclusion and outcome of this study are two fold. First, membrane systems in a pilot plant unit proved to be very efficient in upgrading nonpermeable components in a membrane system and especially when dealing with azeotropic mixtures. For example, more than 99% isopropanol can be produced from a feed liquid which is 88% i-PrOH (azeotropic mixture with water). The membrane system proved to be durable within the time limit of the experiments (120 days). Second, all parameters including the various configurations of the pilot plants (which are still being studied) are available for chemical, petroleum, and other US industries. 3 refs., 22 figs., 2 tabs.

Cabasso, I.; Acharya, H.R.; Korngold, E.; Liu, Z.; Stern, S.A.; Li, W.; Makenzie, T.; Poda, E.

1987-10-01

151

Water content of pyrolysis oil: Comparison between Karl Fischer titration, GC\\/MS-corrected azeotropic distillation and 1H NMR spectroscopy  

Microsoft Academic Search

Pyrolysis converts biomass waste mainly into pyrolysis oil, which is a possible source of renewable energy and\\/or value-added chemicals. A very important characteristic of pyrolysis oil is its water content. Karl Fischer titration and azeotropic distillation by the Dean-Stark method are two common techniques for water determination. In this study, the water content is determined for several pyrolysis oil samples

K. Smets; P. Adriaensens; J. Vandewijngaarden; M. Stals; T. Cornelissen; S. Schreurs; R. Carleer; J. Yperman

2011-01-01

152

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

PubMed

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

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

2010-01-01

153

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

PubMed

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

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

2009-01-01

154

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

155

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

156

The performance of a residential heat pump operating with a nonazeotropic binary refrigerant mixture  

NASA Astrophysics Data System (ADS)

Results of laboratory measurement of the performance change of a substantially unmodified residential heat pump designed for 222 when charged with a non azeotropic, binary mixture of R1381 and R152a is presented. Results are presented for various sizes of fixed expansion devices. The effect of gliding temperature in the saturation zone was found to be small. The effect of compositions shift by flash distillation in the accumulator was found to measurably improve low temperature heating performance. It was further observed that some system modification (such as the addition of a receiver) could have further enhanced this low temperature heating performance improvement.

Didion, D.; Mulroy, W.

157

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

PubMed

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

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

2003-03-15

158

Mixture effects of organic micropollutants present in water: towards the development of effect-based water quality trigger values for baseline toxicity.  

PubMed

In this study we propose for the first time an approach for the tentative derivation of effect-based water quality trigger values for an apical endpoint, the cytotoxicity measured by the bioluminescence inhibition in Vibrio fischeri. The trigger values were derived for the Australian Drinking Water Guideline and the Australian Guideline for Water Recycling as examples, but the algorithm can be adapted to any other set of guideline values. In the first step, a Quantitative Structure-Activity Relationship (QSAR) describing the 50% effect concentrations, EC50, was established using chemicals known to act according to the nonspecific mode of action of baseline toxicity. This QSAR described the effect of most of the chemicals in these guidelines satisfactorily, with the exception of antibiotics, which were more potent than predicted by the baseline toxicity QSAR. The mixture effect of 10-56 guideline chemicals mixed at various fixed concentration ratios (equipotent mixture ratios and ratios of the guideline values) was adequately described by concentration addition model of mixture toxicity. Ten water samples were then analysed and 5-64 regulated chemicals were detected (from a target list of over 200 chemicals). These detected chemicals were mixed in the ratios of concentrations detected and their mixture effect was predicted by concentration addition. Comparing the effect of these designed mixtures with the effect of the water samples, it became evident that less than 1% of effect could be explained by known chemicals, making it imperative to derive effect-based trigger values. The effect-based water quality trigger value, EBT-EC50, was calculated from the mixture effect concentration predicted for concentration-additive mixture effects of all chemicals in a given guideline divided by the sum of the guideline concentrations for individual components, and dividing by an extrapolation factor that accounts for the number of chemicals contained in the guidelines and for model uncertainties. While this concept was established using the example of Australian recycled water, it can be easily adapted to any other set of water quality guidelines for organic micropollutants. The cytotoxicity based trigger value cannot be used in isolation, it must be applied in conjunction with effect-based trigger values targeting critical specific modes of action such as estrogenicity or photosynthesis inhibition. PMID:23618317

Tang, Janet Y M; McCarty, Shane; Glenn, Eva; Neale, Peta A; Warne, Michel St J; Escher, Beate I

2013-06-15

159

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...

160

In vitro study on the effect of organic acids on Campylobacter jejuni/coli populations in mixtures of water and feed.  

PubMed

Gastroenteritis caused by Campylobacter spp. infection has been recognized as one of the important public health problems in the developed countries. Outbreaks mostly originate from the consumption of contaminated poultry or infected water. The aim of this study was to determine the bactericidal activity on Campylobacter spp. of organic acids individually and in combinations at different pH levels and times and to compare bactericidal activities with activities of commercially available products. Ten strains of Campylobacter spp. were added in a mixture of water with commercial broiler feed, separately adjusted by four acids: formic, acetic, propionic, and hydrochloric acids, into pH 4.0, 4.5, 5.0, and 5.5. A combination of three organic acids was used in two different formulation ratios: formic:acetic:propionic at 1:2:3 and 1:2:5, at pH 4.0, 4.5, 5.0, and 5.5. All organic acids showed the strongest bactericidal effect on Campylobacter at pH 4.0. In contrast, at pH 5.0 and 5.5, the bactericidal activity of the four acids was low. The combination of organic acids showed a synergistic bactericidal activity at pH 4.5. Interestingly, the effect of the combined organic acids was stronger than the commercial products. Morphological cell changes were studied by transmission electron microscopy to determine the effect of the organic acids on the cell structure of Campylobacter. Some loss of outer membranes of the bacteria could be found in treated groups. Therefore, it can be concluded that organic acids, individually or in combination, have a strong bactericidal effect on Campylobacter spp. Routine application of organic acids to the water supply on poultry farms could prevent or diminish Campylobacter transmission. PMID:12033410

Chaveerach, P; Keuzenkamp, D A; Urlings, H A P; Lipman, L J A; van Knapen, F

2002-05-01

161

Development of cellulose acetate propionate membrane for separation of ethanol and ethyl tert-butyl ether mixtures  

SciTech Connect

For pervaporation separation of ethanol and ethyl tert-butyl ether mixtures, a cellulose acetate propionate membrane was chosen as the experimental membrane because of its high selectivity and good mass fluxes. The properties of the membranes were evaluated by the pervaporation separation of mixtures of ethyl tert-butyl ether/ethanol and the sorption experiments. The experimental results showed that the selectivity and the permeates depend on the ethanol concentration in the feed and the experimental temperature. With increases of the ethanol weight fraction in the feed and the temperature, the total and partial mass fluxes increased. With respect to the temperature, ethanol mass flux obeys the Arrhenius equation. The selectivity of this membrane decreases as the temperature and the ethanol concentration in the feed increase. This membrane shows special characteristics at the azeotropic composition. In the vicinity of the azeotropic point, minimum values of ethanol concentration in the permeate and in sorption solution are obtained. The swelling ratios increase when temperature and the ethanol concentration in the feed are increasing. The ethanol concentration in the sorption solution is also influenced by the temperature and the mixture`s composition. When the temperature increases, the sorption selectivity of the membrane decreases.

Luo, G.S.; Niang, M.; Schaetzel, P. [Laboratoire D`Automatique et de Procedes, Caen (France)

1997-04-01

162

Mineral contributions to atrazine and alachlor sorption in soil mixtures of variable organic carbon and clay content  

NASA Astrophysics Data System (ADS)

A sediment mixing approach was taken to systematically vary the organic carbon (oc) and clay content (cm) of a suite of organic-poor, clay-rich sediments. Organic carbon content ranged from 3.2% to 0.4% and clay content ranged from 24% to 51%. Atrazine and alachlor were shown to sorb to both natural organic carbon and clay minerals. Partition coefficients to natural organic carbon ( Koc) were found to be 217 and 412 L/kg organic carbon for atrazine and alachlor, respectively. Partition coefficients to the clay fraction were found to be 3.5 and 4.9 L/kg clay for atrazine and alachlor, respectively. When expressed in terms of surface area, the partition coefficients to clay for atrazine and alachlor were 1.80·10 -5 and 2.51·10 -5 L/m 2 clay, respectively. Critical cm/oc ratios at which mineral phase sorption accounts for 50% of the total are defined. Implications for the modelling of herbicide movement in the subsurface if mineral phase sorption is ignored is discussed.

Grundl, Tim; Small, Greg

1993-09-01

163

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

164

Performance of innovative PU-foam and natural fiber-based composites for the biofiltration of a mixture of volatile organic compounds by a fungal biofilm.  

PubMed

The performance of perlite and two innovative carriers that consist of polyurethane (PU) chemically modified with starch; and polypropylene reinforced with agave fibers was evaluated in the biofiltration of a mixture of VOCs composed of hexane, toluene and methyl-ethyl-ketone. At a total organic loading rate of 145 gCm(-3)h(-1) the elimination capacities (ECs) obtained were 145, 24 and 96 gCm(-3)h(-1) for the biofilters packed with the PU, the reinforced polypropylene, and perlite, respectively. Specific maximum biodegradation rates of the mixture, in the biofilters, were 416 mgCg(protein)(-1)? h(-1) for the PU and 63 mgCg(protein)(-1)?h(-1) for perlite, which confirms the highest performance of the PU-composite. 18S rDNA analysis from the PU-biofilter revealed the presence of Fusarium solani in its sexual and asexual states, respectively. The modified PU carrier significantly reduced the start-up period of the biofilter and enhanced the EC of the VOCs. Thus, this study gives new alternatives in the field of packing materials synthesis, promoting the addition of easily biodegradable sources to enhance the performance of biofilters. PMID:22178276

Gutiérrez-Acosta, O B; Arriaga, S; Escobar-Barrios, V A; Casas-Flores, S; Almendarez-Camarillo, A

2012-01-30

165

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

E-print Network

ABSTRACT. Page DEDICATION. ACKNOWLEDGMENT vi TABLE OF CONTENTS vii LIST OF TABLES. . . LIST OF FIGURES. ix INTRODUCTION. LITERATURE REVIEW. Activated Carbon. Adsorption Theory Charcoal Tubes and Passive Dosimeters. Relative Humidity... agents is by sampling for contaminants. The use of solid adsorbents is one of the most important methods for monitoring harmful organic vapors in the workplace. ( The charcoal tube method (activated carbon adsorption- solvent desorption...

Rushlow, Lori Ann

1989-01-01

166

Photosynthetic based algal-bacterial combined treatment of mixtures of organic pollutants and CO2 mitigation in a continuous photobioreactor.  

PubMed

An algal-bacterial microcosm was synthetically constructed of Chlorella vulgaris MMl and Pseudomonas MTl. This microcosm was able to treat simulated wastewater supplemented with mixtures of phenol and pyridine up to 4.6 and 4.4 mM, respectively, in a continuous stirred tank bioreactor (CSTR) using photosynthetic oxygenation. Complete pollutant removal and detoxification and 82 % removal of introduced chemical oxygen demand (COD) were achieved at a hydraulic retention time (HRT) of 2.7 days. Increasing the influent load to 5.3 and 6.3 mM reduced the removal of phenol, pyridine and COD to 78, 21 and 59 %, respectively. Fertilization of the photobioreactor with 24 mM NaHCO3 restored the treatment and detoxification efficiencies. The system was able to additionally mitigate up to 72 mM NaHCO3 at the same HRT. Although the fertilization increased the system treatment efficiency, the settleability of the algal-bacterial microcosm was significantly reduced. When the photobioreactor was operated at HRT of 2.7 days in a 12/12 h of dark/light cycle, complete removal of 4.7 mM phenol was recorded but only 11 % of 5.7 mM pyridine was removed. The COD removal efficiency and CO2 mitigation were also reduced to 65 and 86 %, respectively, and the effluent retained significant toxicity where 73 % inhibition was recorded. Elongation of the illumination time to 48 h (HRT of 4 days at 12/12 h dark/light cycle) restored the treatment and detoxification efficiencies. PMID:23296918

Essam, Tamer; ElRakaiby, Marwa; Hashem, Abdelgawad

2013-06-01

167

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

PubMed Central

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

2011-01-01

168

Separating Mixtures  

NSDL National Science Digital Library

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

2014-09-18

169

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

170

Effect of mixture ratio, solids concentration and hydraulic retention time on the anaerobic digestion of the organic fraction of municipal solid waste.  

PubMed

This paper describes how the degradation of the organic fraction of municipal solid waste (OFMSW) is affected through codigestion with varying amounts of return activated sludge (RAS). Solid waste that had its inorganic fraction selectively removed was mixed with RAS in ratios of 100% OFMSW, 50% OFMSW/50% RAS, and 25% OFMSW/75% RAS. The total solids (TS) concentration was held at 8% and three anaerobic digester systems treating the mixtures were held (for the first run) at a total hydraulic retention time (HRT) of 28 days. Increasing amounts of RAS did not however improve the mixture's digestability, as indicated by little change and/or a drop in the main performance indices [including percentage volatile solids (VS) removal and specific gas production]. The optimum ratio in this research therefore appeared to be 100% OFMSW with an associated 85.1 ± 0.6% VS removal and 0.72 ± 0.01 L total gas g(- 1) VS. In the second run, the effect of increasing percentage of TS (8, 12% and 15%) at a system HRT of 28 days was observed to yield no improvement in the main performance indices (i.e. percentage VS removal and specific gas production). Finally, during the third run, variations in the total system HRT were investigated at an 8% TS, again using 100% OFMSW. Of the HRTs explored (23, 28 and 33 days), the longest HRT yielded the best performance overall, particularly in terms of specific gas production (0.77 ± 0.01 L total gas g(-1) VS). PMID:20142413

Fongsatitkul, Prayoon; Elefsiniotis, Panagiotis; Wareham, David G

2010-09-01

171

Effects of a Mixture of Volatile Organic Compounds on Total DNA and Gene Expression of Heat Shock Proteins in Drosophila melanogaster.  

PubMed

The genotoxic effects of a mixture of 13 volatile organic compounds (VOCs) on total DNA profiles and the expression of heat shock proteins (HSPs) HSP26, HSP60, HSP70, and HSP83 in fruit fly tissues were examined. Drosophila melanogaster Oregon R(+), reared under controlled conditions on artificial diets, was treated with 13 VOCs commonly found in water at concentrations of 10, 20, 50, and 75 ppb for 1 and 5 days. Band changes were clearly detected in random amplified polymorphic DNA assay, especially at the 50- and 75-ppb exposure levels, for both treatment periods. In addition, there were clear differences in the band profiles of the treated and untreated flies with changes in the band intensity and the loss/appearance of bands. Although the genomic template stability (GTS) exhibited irregular changes at the first day, significant decreases in GTS were observed after 5 days of VOC application. The lowest GTS value (27.77 ± 1.96 %) was detected at the 75-ppb level after 5 days of the treatment. Quantitative real-time polymerase chain reaction analysis showed a significant increase in the relative expression of HSP26 and HSP60 after 1 and 5 days of the treatment, respectively. The expression of HSP70 increased significantly at all treatment concentrations and times. However, the greatest increase in expression level of HSP70 (4.2-fold) occurred at 20 ppb after 5 days of the treatment. HSP83 was the least affected by exposure to the VOCs. We conclude that trace levels of a mixture of VOCs can exert genotoxic effects on both total DNA and HSP levels in Drosophila. PMID:25352441

Doganlar, Oguzhan; Doganlar, Zeynep Banu

2015-02-01

172

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

173

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

SciTech Connect

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

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

1997-07-01

174

Mixtures and Solutions  

NSDL National Science Digital Library

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

Integrated Teaching and Learning Program,

175

A respirometric method for characterising the organic composition and biodegradation kinetics and the temperature influence on the biodegradation kinetics, for a mixture of sludge and bulking agent to be co-composted  

Microsoft Academic Search

A respirometric method was set up to study kinetics of biological reactions involved in the treatment of organic wastes––sludge mixed with pine barks––by composting. Oxygen consumption rates of this type of mixture were monitored during 10–20 days, using a 10 l respirometric cell kept at constant temperature and moisture. Oxygen consumption kinetics were modelled and organic matter composition was characterised

A. Tremier; A. de Guardia; C. Massiani; E. Paul; J. L. Martel

2005-01-01

176

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

177

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

178

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

NASA Astrophysics Data System (ADS)

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

Mukherjee, Manjori; Mishra, Pankaj; Löwen, Hartmut

2014-11-01

179

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

PubMed

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

Mukherjee, Manjori; Mishra, Pankaj; Löwen, Hartmut

2014-11-19

180

Horizontal-flow boiling heat transfer using refrigerant mixtures: Final report  

SciTech Connect

Mixture effects were studied on horizontal convective heat transfer for both nonazeotropic, R22/R114, and azeotropic, R12/R152a, mixtures. A test facility was designed, constructed, and operated to simulate evaporators in heat pump and refrigeration systems. More than 3000 local two-phase heat transfer coefficients were obtained under steady state condition for annular flow at a reduced pressure of 0.08. The results indicated that there were two distant heat transfer regions; partial boiling and convective evaporation. In the partial boiling region, heat transfer coefficients were strongly dependent upon heat flux; the heat flux dependence disappeared for high vapor qualities. A full suppression of nucleate boiling was observed for both pure and mixed refrigerants. For a given heat and mass flux, nucleate boiling was suppressed at lower qualities for mixtures than for pure fluids. The unique phenomenon of loss of available superheat for mixtures caused nucleate boiling to be suppressed at lower qualities. An analytical study was performed to predict the transition quality by utilizing a theory of onset of nuclear boiling and phase equilibrium data. The prediction agreed very well with the present data. 77 refs., 62 figs., 14 tabs.

Jung, D.S.; Didion, D.A.

1989-05-01

181

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

PubMed

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

Iqbal, Mohammad Asif; Kim, Ki-Hyun

2014-12-19

182

Sorption of organics and water on starch  

SciTech Connect

Starch is a well-established adsorption agent for drying ethanol. This work examines its potential for other gas-phase drying applications. Results from gas chromatography studies confirm that starch separates water from organic acids, alcohols, ketones, ethers, and aromatics, many of which form azeotropes with water. Trends in organics with respect to size and functional group show that the efficiency of this separation is related to both transport properties and strength of interaction between the organic components and starch. Small, polar molecules such as methanol and formic acid that have rapid mass-transfer characteristics and relatively strong interactions with starch are retained to a greater degree and are more difficult to separate from water than either compounds of higher molecular weight or decreased polarity. The large number of possible separations indicates that starch is a versatile material for use in sorbents for vapor-phase separations.

Westgate, P.J.; Ladisch, M.R. (Purdue Univ., West Lafayette, IN (United States). Lab. of Renewable Resources Engineering)

1993-08-01

183

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

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

184

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

185

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

186

Six interaction profiles for simple mixtures.  

PubMed

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 Mixtures). ATSDR also developed six interaction profiles for chemical mixtures. Two profiles were developed for persistent environmental chemicals that are often found in contaminated fish and also can be detected in human breast milk. The mixture included chlorinated dibenzo-p-dioxins, hexachlorobenzene, dichlorodiphenyl dichloroethane, methyl mercury, and polychlorinated biphenyls. Two profiles each were developed for mixtures of metals and mixtures of volatile organic chemicals (VOCs) that are frequently found at hazardous waste sites. The two metal profiles dealt with (a) lead, manganese, zinc, and copper; and (b) arsenic, cadmium, chromium, and lead; the two VOCs mixtures dealt with (a) 1,1,1-trichloroethane, 1,1-dichloroethane, trichloroethylene, and tetrachloroethylene; and (b) benzene, ethylbenzene, toluene, and xylenes (BTEX). Weight-of-evidence methodology was used to assess the joint toxic action for most of the mixtures. Physiologically based pharmacokinetic modeling was used for BTEX. In most cases, a target-organ toxicity dose modification of the hazard index approach is recommended for conducting exposure-based assessments of noncancer health hazards. PMID:12892681

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

2003-10-01

187

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

188

DETERMINATION OF 2-METHYL TETROLS AND 2-METHYLGLYCERIC ACID IN SECONDARY ORGANIC AEROSOL FROM LABORATORY IRRADIATED ISOPRENE/NO X/SO 2/AIR MIXTURES  

EPA Science Inventory

This presentation addresses recent work performed at EPA to evaluate the potential for the photooxidation of isoprene to produce secondary organic aerosol. Analysis of the samples for methyl tetrols and 2-methylglyceric acid were performed at EPA and the University of Antwerp. T...

189

Direct comparison of a covalently-linked dyad and a 1:1 mixture of tetrabenzoporphyrin and fullerene as organic photovoltaic materials.  

PubMed

A p-i-n organic photovoltaic cell with tetrabenzoporphyrin (BP), a BP-C?? dyad and PCBM for the p-, i- and n-layers, respectively, gave a better fill factor and power conversion efficiency than the corresponding p-i-n cell having a 1:1 blend film of BP and PCBM as the i-layer. PMID:24956974

Tamura, Yuto; Saeki, Hiroyuki; Hashizume, Junpei; Okazaki, Yukinori; Kuzuhara, Daiki; Suzuki, Mitsuharu; Aratani, Naoki; Yamada, Hiroko

2014-09-18

190

Crystallization using reverse micelles and water-in-oil microemulsion systems: the highly selective tool for the purification of organic compounds from complex mixtures.  

PubMed

The active pharmaceutical ingredient orlistat is usually manufactured using a semi-synthetic procedure, producing crude product and complex mixtures of highly related impurities with minimal side-chain structure variability. It is therefore crucial for the overall success of industrial/pharmaceutical application to develop an effective purification process. In this communication, we present the newly developed water-in-oil reversed micelles and microemulsion system-based crystallization process. Physiochemical properties of the presented crystallization media were varied through surfactants and water composition, and the impact on efficiency was measured through final variation of these two parameters. Using precisely defined properties of the dispersed water phase in crystallization media, a highly efficient separation process in terms of selectivity and yield was developed. Small-angle X-ray scattering, high-performance liquid chromatography, mass spectrometry, and scanning electron microscopy were used to monitor and analyze the separation processes and orlistat products obtained. Typical process characteristics, especially selectivity and yield in regard to reference examples, were compared and discussed. PMID:23161204

Kljajic, Alen; Bester-Rogac, Marija; Klobcar, Andrej; Zupet, Rok; Pejovnik, Stane

2013-02-01

191

Mixtures of quaternary ammonium compounds and anionic organic compounds in the aquatic environment: Elimination and biodegradability in the closed bottle test monitored by LC-MS/MS.  

PubMed

Quaternary ammonium compounds (QACs) are widely used as disinfectants, detergents and fabric softeners. Anionic detergents are one of the most widely used chemical substances. QACs and anionic surfactants can form ionic pairs. In the present study we investigated the biodegradability of QACs in the presence of different anionic surfactants. The biodegradability of three QACs, namely benzalkonium chloride (BAC), didecyldimethylammonium chloride (DDMAC) and ethacridine lactate (EL), when applied as single substances and in combination with anionic surfactants such as benzene sulfonic acid (BSA), LAS, naphthalene sulfonic acid (NSA) and sodium dodecylsulfonate (SDS) was studied applying the closed bottle test (CBT) [OECD 301D, 1992. Guidelines for Testing of Chemicals. Closed bottle test. Organisation of Economic Cooperation and Development, Paris] at a ratio of 1:1 (mol:mol). Biodegradation was monitored by measuring oxygen concentration in the test vessels with an oxygen electrode in accordance with international standard methods [ISO 5414, 1990. Water quality - determination of dissolved oxygen. In: German Standard Methods for the Examination of Water, Wastewater and Sludge. VCH Verlagsgesellschaft, Weinheim, New York, Basel Cambridge]. Primary elimination of the QACs and of LAS was monitored by LC-MS/MS. There was little biodegradability of the QACs as either single compounds or in the presence of organic counter ions. The biodegradability of the organic counter ions was lower in the presence of QACs as compared to the single substances. Primary elimination of the QACs by sorption took place. PMID:18439651

Sütterlin, H; Alexy, R; Coker, A; Kümmerer, K

2008-06-01

192

Mixtures Research at NIEHS: An Evolving Program  

PubMed Central

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

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

2014-01-01

193

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

PubMed

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

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

2014-10-24

194

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

195

Element, Mixture, Compound  

NSDL National Science Digital Library

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

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

196

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.

197

Occupational exposure to complex mixtures of volatile organic compounds in ambient air: desorption from activated charcoal using accelerated solvent extraction can replace carbon disulfide?  

PubMed

A desorption study of 57 volatile organic compounds (VOCs) has been conducted by use of accelerated solvent extraction (ASE) and gas chromatography-mass spectrometry. Different solvents were tested to extract activated charcoal tubes with the objective of replacing carbon disulfide, used in official methods, because of its highly toxic health and environmental effects. Extraction conditions, for example temperature and number of cycles, were investigated and optimized. The definitive extraction procedure selected was use of acetone at 150 °C and two consecutive extraction cycles at a pressure of 1,500 psi. Considering a sample volume of 0.005 Nm(3), corresponding to a sampling time of 8 h at a flow rate of 0.01 L min(-1), the method was validated over the concentration range 65-26,300 ?g Nm(-3). The lowest limit of quantification was 6 ?g Nm(-3), and recovery for the 93 % of analytes ranged from 65 to 102 %. For most of the compounds, relative standard deviations were less than 15 % for inter and intra-day precision. Uncertainty of measurement was also determined: the relative expanded uncertainty was always below 29.6 %, except for dichlorodifluoromethane. This work shows that use of friendlier solvent, for example acetone, coupled with use of ASE, can replace use of CS(2) for chemical removal of VOCs from activated charcoal. ASE has several advantages over traditional solvent-extraction methods, including shorter extraction time, minimum sample manipulation, high reproducibility, and less extraction discrimination. No loss of sensitivity occurs and there is also a salutary effect on bench workers' health and on the smell of laboratory air. PMID:22968683

Fabrizi, Giovanni; Fioretti, Marzia; Rocca, Lucia Mainero

2013-01-01

198

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

199

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

200

Mixtures and Solutions  

Microsoft Academic Search

\\u000a The world around us is made not of pure substances but of mixtures. The air is a mixture of dinitrogen and dioxygen and small amounts of other gases and vapors. The blood flowing through our\\u000a veins and arteries is a mixture of water and many thousands of other molecules. When we add salt, NaCl, to water and let it\\u000a dissolve

Predrag-Peter Ilich

201

Mixtures of ionic liquids.  

PubMed

Simple ionic liquids have long been held to be designer solvents, based upon the ability to independently vary their cations and anions. The formation of mixtures of ionic liquids increases this synthetic flexibility. We review the available literature of these ionic liquid mixtures to identify how their properties change and the possibility for their application. PMID:22890419

Niedermeyer, Heiko; Hallett, Jason P; Villar-Garcia, Ignacio J; Hunt, Patricia A; Welton, Tom

2012-12-01

202

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

203

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

204

Perception of trigeminal mixtures.  

PubMed

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

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

2015-01-01

205

SHORT-TERM BIOASSAYS IN THE ANALYSIS OF COMPLEX ENVIRONMENTAL MIXTURES V  

EPA Science Inventory

Topics presented in the book are: new chemical and biological methods in complex mixture research; molecular dosimetry as applied to complex mixtures; integrated in-situ monitoring; genotoxicology of aquatic organisms; atmospheric transportation processes in the production of gen...

206

Condensate Mixtures and Tunneling  

SciTech Connect

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

Timmermans, E.

1998-09-14

207

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

208

MIXTURES FEASIBILITY STUDY  

EPA Science Inventory

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

209

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

210

Energy efficient membrane processes for the separation of organic liquids: Part 2: Final report, September 28, 1982--December 31, 1986  

SciTech Connect

The present report demonstrates the use of membrane technology for dehydration processes concentrating on two examples: azeotropic separation of isopropanol-water, and separation of ethanol-water mixtures (starting at 84.5 wt. % ethanol where separation by distillation begins to be progressively more energy intensive). The principles of the membrane separation processes employed in such separations were discussed in Part I of the report. The advantage of the membrane processes is that they do not require the addition of a third component and separation is a continuous process. Pervaporation, perstraction, and air-sweep pervaporation were thoroughly studied for these separations. An urgent need for the identification of the appropriate membrane was realized. This study has revealed that ion-exchange membranes are suited for these separations. Results are discussed. 9 refs., 68 figs., 33 tabs.

Cabasso, I.; Acharya, H.R.; Korngold, E.; Liu, Z.; Stern, S.A.; Li, W.; Makenzie, T.; Poda, E.

1987-10-01

211

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

212

Effect of stirring on the safety of flammable liquid mixtures.  

PubMed

Flash point is the most important variable employed to characterize fire and explosion hazard of liquids. The models developed for predicting the flash point of partially miscible mixtures in the literature to date are all based on the assumption of liquid-liquid equilibrium. In real-world environments, however, the liquid-liquid equilibrium assumption does not always hold, such as the collection or accumulation of waste solvents without stirring, where complete stirring for a period of time is usually used to ensure the liquid phases being in equilibrium. This study investigated the effect of stirring on the flash-point behavior of binary partially miscible mixtures. Two series of partially miscible binary mixtures were employed to elucidate the effect of stirring. The first series was aqueous-organic mixtures, including water+1-butanol, water+2-butanol, water+isobutanol, water+1-pentanol, and water+octane; the second series was the mixtures of two flammable solvents, which included methanol+decane, methanol+2,2,4-trimethylpentane, and methanol+octane. Results reveal that for binary aqueous-organic solutions the flash-point values of unstirred mixtures were located between those of the completely stirred mixtures and those of the flammable component. Therefore, risk assessment could be done based on the flammable component flash-point value. However, for the assurance of safety, it is suggested to completely stir those mixtures before handling to reduce the risk. PMID:20116168

Liaw, Horng-Jang; Gerbaud, Vincent; Chen, Chan-Cheng; Shu, Chi-Min

2010-05-15

213

Protective slurry mixture  

SciTech Connect

A slurry mixture is described used in transferring porous catalyst particles from a catalyst reservoir at a temperature in the range of from room temperature to about 200/sup 0/F to a reactor site of higher temperature in the range of up to 1000/sup 0/F and lower pressure which mixture comprises a suspension of the porous catalyst particles in a carrier fluid wherein the critical temperature of the carrier fluid is above the temperature of the reactor site, the boiling point at atmospheric pressure of the carrier fluid is lower than the temperature of the reactor site and the critical pressure of the fluid is below the ambient pressure of the reactor site.

Chen, H.C.

1989-02-28

214

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

EPA Science Inventory

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

215

Transcriptional responses to complex mixtures: a review.  

PubMed

Exposure of people to hazardous compounds is primarily through complex environmental mixtures, those that occur through media such as air, soil, water, food, cigarette smoke, and combustion emissions. Microarray technology offers the ability to query the entire genome after exposure to such an array of compounds, permitting a characterization of the biological effects of such exposures. This review summarizes the published literature on the transcriptional profiles resulting from exposure of cells or organisms to complex environmental mixtures such as cigarette smoke, diesel emissions, urban air, motorcycle exhaust, carbon black, jet fuel, and metal ore and fumes. The majority of the mixtures generally up-regulate gene expression, with heme oxygenase 1 and CYP1A1 being up-regulated by all of the mixtures. Most of the mixtures altered the expression of genes involved in oxidative stress response (OH-1, metallothioneins), immune/inflammation response (IL-1b, protein kinase), xenobiotic metabolism (CYP1A1, CYP1B1), coagulation and fibrinolysis (plasminogen activator/inhibitor), proto-oncogenes (FUS1, JUN), heat-shock response (HSP60, HSP70), DNA repair (PCNA, GADD45), structural unit of condensed DNA (Crf15Orf16, DUSP 15), and extracellular matrix degradation (MMP1, 8, 9, 11, 12). Genes involved in aldehyde metabolism, such as ALDH3, appeared to be uniquely modulated by cigarette smoke. Cigarette smoke-exposed populations have been successfully distinguished from control nonexposed populations based on the expression pattern of a subset of genes, thereby demonstrating the utility of this approach in identifying biomarkers of exposure and susceptibility. The analysis of gene-expression data at the pathway and functional level, along with a systems biology approach, will provide a more comprehensive insight into the biological effects of complex mixtures and will improve risk assessment of the same. We suggest critical components of study design and reporting that will achieve this goal. PMID:17888717

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

2007-01-01

216

Oxidative particle mixtures for groundwater treatment  

DOEpatents

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

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

2000-01-01

217

Toxicological approaches to complex mixtures.  

PubMed Central

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

Mauderly, J L

1993-01-01

218

Zwanzig model of multi-component mixtures of biaxial particles: y3 theory re-visited  

NASA Astrophysics Data System (ADS)

The paper considers the thermodynamic and phase ordering properties of a multi-component Zwanzig mixture of hard rectangular biaxial parallelepipeds. An equation of state (EOS) is derived based on an estimate of the number of arrangements of the particles on a three- dimensional cubic lattice. The methodology is a generalization of the Flory-DiMarzio counting scheme, but, unlike previous work, this treatment is thermodynamically consistent. The results are independent of the order in which particles are placed on the lattice. By taking the limit of zero lattice spacing, a translationally continuous variant of the model (the off-lattice variant) is obtained. The EOS is identical to that obtained previously by a wide variety of different approaches. In the off-lattice limit, it corresponds to a third-level y-expansion and, in the case of a binary mixture of square platelets, it also corresponds to the EOS obtained from fundamental measure theory. On the lattice it is identical to the EOS obtained by retaining only complete stars in the virial expansion. The off-lattice theory is used to study binary mixtures of rods (R1 - R2) and binary mixtures of platelets (P1 - P2). The particles were uniaxial, of length (thickness) L and width D. The aspect ratios ?i = Li/Di of the components were kept constant (?1R = 15, ?1P = 1/15 and ?2R = 150, ?2P = 1/150), so the second virial coefficient of R1 was identical to P1 and similarly for R2 and P2. The volume ratio of particles 1 and 2, v1/v2, was then varied, with the constraints that viR = viP and ILM0001. Results on nematic-isotropic (N - I) phase coexistence at an infinite dilution of component 2, are qualitatively similar for rods and platelets. At small values of the ratio v1/v2, the addition of component 2 (i.e. a thin rod (e.g. a polymer) or a thin plate) results in the stabilization of the nematic phase. For larger values of v1/v2, however, this effect is reversed and the addition of component 2 destabilizes the nematic. For similar molecular volumes of the two components strong fractionation is observed: shorter rods and thicker platelets congregate in the isotropic phase. In general, the stabilization of the ordered phase and the fractionation between the phases are both weaker in the platelet mixtures. The calculated spinodal curves for isotropic-isotropic demixing are noticeably different between the R1 - R2 and the P1 - P2 systems. The platelet mixtures turn out to be stable with respect to de-mixing up to extremely high densities. The values of the consolute points for the R1 - R2 blends are remarkably similar to those obtained using the Parsons-Lee approximation for bi-disperse mixtures of freely rotating cylinders with similar aspect ratios [S. Varga. A. Galindo, G. Jackson, Mol. Phys., 101, 817 (2003)]. In a number of R1 - R2 mixtures, phase diagrams exhibiting both N - I equilibrium and I - I de-mixing were calculated. The latter is pre-empted by nematic ordering in all the cases studied. Calculations show the possible appearance of azeotropes in the N - I coexistence domain.

Sokolova, E. P.; Tumanyan, N. P.; Vlasov, A. Yu.; Masters, A. J.

219

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

220

Practical Bayesian Inference Using Mixtures of Mixtures Guoliang Cao  

E-print Network

analysis. 1. Introduction Key words: Dirichlet processes; Markov chain Monte Carlo; Mixtures of normal amplitude fluctuations of electrical potentials at synapses of human, and other animal nervous sys­ tems, though often the evidence suggests that a non­normal noise model, such as a mixture of a small number

West, Mike

221

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 323K. 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

222

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.

223

Dirichlet Mixtures in Text Modeling  

Microsoft Academic Search

Word rates in text vary according to global factors such as genre, topic, author, and expected readership (Church and Gale 1995). Models that summarize such global factors in text or at the document level, are called 'text models.' A finite mixture of Dirichlet distribution (Dirichlet Mixture or DM for short) was investigated as a new text model. When parameters of

Mikio Yamamoto; Kugatsu Sadamitsu

224

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...

225

COMPLEX MIXTURES AND GROUNDWATER QUALITY  

EPA Science Inventory

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

226

Bridging environmental mixtures and toxic effects  

PubMed Central

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

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

2012-01-01

227

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

228

Modeling and analysis of personal exposures to VOC mixtures using copulas  

PubMed Central

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

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

2014-01-01

229

Some results on Gaussian mixtures  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

230

ENZYMATIC HYDROLYSIS OF CLOVER-GRASS MIXTURES FOR ETHANOL  

E-print Network

ENZYMATIC HYDROLYSIS OF CLOVER- GRASS MIXTURES FOR ETHANOL PRODUCTION MARTÍN, C.1,2 , THOMSEN, M. H, Risø National Laboratory, P.O.Box 49, DK-4000 Roskilde, Denmark Clover (Trifolium repens L.)-grass.g. organic farming systems. Since clover and grass are rich in carbohydrates, mainly cellulose

231

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

E-print Network

of intensive current research. The effects of multicontaminant exposure on humans are uncertain, and additionalVOCs, Pesticides, Nitrate, and Their Mixtures in Groundwater Used for Drinking Water in the United areas. For each sample, as many as 60 volatile organic compounds (VOCs), 83 pesticides, and nitrate were

232

Predicting the toxicity of metal mixtures.  

PubMed

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

Balistrieri, Laurie S; Mebane, Christopher A

2014-01-01

233

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

DOEpatents

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

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

1995-01-01

234

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

DOEpatents

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

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

1995-09-26

235

14 CFR 23.1147 - Mixture controls.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Mixture controls. 23.1147 Section 23.1147 Aeronautics...CATEGORY AIRPLANES Powerplant Powerplant Controls and Accessories § 23.1147 Mixture controls. (a) If there are mixture...

2010-01-01

236

14 CFR 25.1147 - Mixture controls.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Mixture controls. 25.1147 Section 25.1147 Aeronautics...CATEGORY AIRPLANES Powerplant Powerplant Controls and Accessories § 25.1147 Mixture controls. (a) If there are mixture...

2010-01-01

237

14 CFR 23.1147 - Mixture controls.  

Code of Federal Regulations, 2011 CFR

...2011-01-01 2011-01-01 false Mixture controls. 23.1147 Section 23.1147 Aeronautics...CATEGORY AIRPLANES Powerplant Powerplant Controls and Accessories § 23.1147 Mixture controls. (a) If there are mixture...

2011-01-01

238

14 CFR 25.1147 - Mixture controls.  

Code of Federal Regulations, 2011 CFR

...2011-01-01 2011-01-01 false Mixture controls. 25.1147 Section 25.1147 Aeronautics...CATEGORY AIRPLANES Powerplant Powerplant Controls and Accessories § 25.1147 Mixture controls. (a) If there are mixture...

2011-01-01

239

Handbook of physical properties of liquids and gases - pure substances and mixtures. Second edition  

Microsoft Academic Search

Numerical physical property data is included for pure substances such as hydrogen, hydrogen compounds, metals, carbon compounds, hydrocarbons, organic compounds, nitrogen, ammonia, oxygen, sulfur dioxide, halogens, and monoatomic gases. Air, gas mixtures, solutions, liquid fuels, high-temperature heat transfer fluids, and oils are among the mixtures whose physical properties are included in this handbook. Binary gas diffusion coefficients at one atmosphere

Vargaftik

1975-01-01

240

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

Microsoft Academic Search

Acute toxicity of the bronchodilator saponin mixture isolated from Schefflera leucantha Viguier leaves was investigated in comparison with the methanol and the water extract of this plant. Oral doses of 5000mg\\/kg of the methanol extract, the water extract and the saponin mixture did not produce mortality or significant changes in the general behavior and gross appearance of internal organs of

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

2003-01-01

241

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

DOEpatents

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

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

2011-01-04

242

PREDICTION OF THE SOLUBILITY OF HYDROPHOBIC COMPOUNDS IN NONIDEAL SOLVENT MIXTURES  

EPA Science Inventory

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

243

PREDICTION OF THE SOLUBILITY OF HYDROPHOBIC COMPOUNDS IN NONIDEAL SOLVENT MIXTURES  

EPA Science Inventory

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

244

Absorption of sound in liquids and liquid mixtures  

E-print Network

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

Musa, Raiq S

1955-01-01

245

Estimating proportions of materials using mixture models  

NASA Technical Reports Server (NTRS)

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

Heydorn, R. P.; Basu, R.

1983-01-01

246

Designs for Mixture Experiments Involving Process Variables  

Microsoft Academic Search

Published procedures for mixture experimentation in the presence of process variables arc reviewed. Procedures which inscribe figures in the mixture space result in lower numbers of experiments but are limited because they do not permit full exploration of the mixture space. In this paper, alternative procedures which minimize the loss of the mixture space are presented. Eight cases representing all

Lynne B. Hare

1979-01-01

247

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

PubMed

Solid reactive mixtures were tested as filling material for the development of biological permeable reactive barriers for the treatment of heavy metals contaminated waters. Mixture selection was performed by taking into account the different mechanisms operating in sulphate and cadmium removal with particular attention to bioprecipitation and sorption onto the organic matrices in the mixtures. Suspensions of eight reactive mixtures were tested for sulphate removal (initial concentration 3 g L(-1)). Each mixture was made up of four main functional components: a mix of organic sources for bacterial growth, a neutralizing agent, a porous medium and zero-valent iron. The best mixture among the tested ones (M8: 6% leaves, 9% compost, 3% zero-valent iron, 30% silica sand, 30% perlite, 22% limestone) presented optimal conditions for SRB growth (pH 7.8 +/- 0.1; E(h)= -410 +/- 5 mV) and 83% sulphate removal in 22 days (25% due to bioreduction, 32% due to sorption onto compost and 20% onto leaves). M8 mixture allowed the complete abatement of cadmium with a significant contribution of sorption over bioprecipitation (6% Cd removal due to SRB activity). Sorption properties, characterised by potentiometric titrations and related modelling, were mainly due to carboxylic sites of organic components used in reactive mixtures. PMID:19505754

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

2009-10-30

248

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

249

An improved Gaussian mixture model  

NASA Astrophysics Data System (ADS)

An improved Gaussian mixture model is presented to substitute the typical method of Chris Stauffer which revealed its weakness in uncontrollability of the background constructing course and foreground mergence time as well as invalidation to the low duty background. By setting appropriate time parameters which meet the monitoring needs, the improved method effectively controls the estimates updating process of each background in Gaussian mixture model via layered attenuating the estimates and intensifying the recurrence events while requires almost the same computation. The simulation of traffic monitoring videos indicates that: this model has no scraps of provisionally staying objects, efficaciously picks up the low duty background.

Gong, Dayong; Wang, Zhihua

2013-03-01

250

Ultrasonic absorption in liquid mixtures  

E-print Network

and metnanol with water at a tempexatuxm o of 18 G aud a frequency of 12i7 mci For the ethanol-water mizture they found a strong peak in absorption at a concentration of approximately 804 alcohol by volume+ For the zzzthauo~tsr sdxture they reported ac... was deoreussd from 25 G to 0 Gx it seemed worthwhile to investigate the mixture at a still loser tem- perature. the naia oh)ective in stu~ the methanol-water mixture was sn attempt to find a maximum in the absorption at an intermediate concen tration...

Davis, James Madison

1954-01-01

251

Dipole oscillations in fermionic mixtures  

SciTech Connect

We study dipole oscillations in a general fermionic mixture. Starting from the Boltzmann equation, we classify the different solutions in the parameter space through the number of real eigenvalues of the small oscillations matrix. We discuss how this number can be computed using the Sturm algorithm and its relation with the properties of the Laplace transform of the experimental quantities. After considering two components in harmonic potentials having different trapping frequencies, we study dipole oscillations in three-component mixtures. Explicit computations are done for realistic experimental setups using the classical Boltzmann equation without intraspecies interactions. A brief discussion of the application of this classification to general collective oscillations is also presented.

Chiacchiera, S.; Macri, T.; Trombettoni, A. [Centro de Fisica Computacional, Department of Physics, University of Coimbra, P-3004-516, Coimbra (Portugal); SISSA and INFN, Sezione di Trieste, via Beirut 2/4, I-34151, Trieste (Italy)

2010-03-15

252

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

PubMed Central

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

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

2002-01-01

253

Si l ti f Eth l D h d ti 2013 9 23()  

E-print Network

point. Ethanol / Water System rMoleFractionofEthanol 0.3 0.4 0.5 0.6 0.7 0.8 0.9 Binary azeotropic.0 0.1 0.2 y p boiling point than any binary azeotrope #12;Separation of Azeotropic Mixture Shift mixtures, such as ethanol/water and IPA/water, can be separated into their pure components by distillation

Hong, Deog Ki

254

Entanglement teleportation via Bell Mixture  

Microsoft Academic Search

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

Sibasish Ghosh; Guruprasad Kar; Anirban Roy

255

Thermal Conductivities of Liquid Mixtures  

Microsoft Academic Search

This paper focuses on the empirical correlation of evaluated thermal conductivities of binary mixtures at different temperatures, the published correlations based on experimental thermal conductivities, the characterization properties for estimation at critical temperature, boiling point and critical volume for component 1, weight fraction for component 2, and thermal conductivity for components 1 and 2. Multiple regression analysis was used to

I. E. Maloka

2007-01-01

256

Centrifugal separation of a mixture  

Microsoft Academic Search

In this review, we shall present a survey about recent developments in the understanding of the separation of a mixture in a rotating vessel. Based on the first principles of fluid dynamics and earlier substantial results concerned with gravity settling, recently a great variety of investigations has been published for different centrifugal devices and ranges of parameters. We shall summarize

Uwe Schaflinger

1990-01-01

257

Heat and Gravitation. III. Mixtures  

E-print Network

The standard treatment of relativistic thermodynamics does not allow for a systematic treatment of mixtures. It is proposed that a formulation of thermodynamics as an action principle may be a suitable approach to adopt for a new investigation. This third paper of the series applies the action principle to a study of mixtures of ideal gases. The action for a mixture of ideal gases is the sum of the actions for the components, with an entropy that, in the absence of gravity, is determined by the Gibbs-Dalton hypothesis. Chemical reactions such as hydrogen dissociation are studied, with results that include the Saha equation and that are more complete than traditional treatments, especially so when gravitational effects are included. A mixture of two ideal gases is a system with two degrees of freedom and consequently it exhibits two kinds of sound. In the presence of gravity the Gibbs-Dalton hypothesis is modified to get results that agree with observation. The possibility of a parallel treatment of real gases is illustrated by an application to van der Waals gases. The overall conclusion is that experimental results serve to pin down the lagrangian in a very efficient manner. This leads to a convenient theoretical framework in which many dynamical problems can be studied.

Christian Fronsdal

2010-06-08

258

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

Microsoft Academic Search

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

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

1998-01-01

259

Weakly interacting colloid polymer mixtures  

NASA Astrophysics Data System (ADS)

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

Prasad, Vikram

260

Engineering Organic/inorganic hybrids comprise a mixture of oxide  

E-print Network

interactions. Our recent studies have revealed that the strength of acid-base interactions can be fine species on the C-H and N-H groups of the amino silica. Development of an effective and stable sorbent requires a fundamental understanding of CO2- O2-amine interactions. This presentation will review the basic

261

Analysis of Analgesic Mixtures: An Organic Chemistry Experiment.  

ERIC Educational Resources Information Center

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

Martin, Ned H.

1981-01-01

262

Moderate strength lightweight concrete from organic aquagel mixtures  

Microsoft Academic Search

The present study describes a new approach for making lightweight concrete that uses aquagels in the concrete formulation. Aquagels are semi-rigid gels that contain mostly water and a small amount of solids that act as the gelling agent. Aquagels were made using wheat starch, algin, agar and high amylose corn starch (HACS). Concrete samples were made using each of the

G. M Glenn; R. M Miller; W. J Orts

1998-01-01

263

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

264

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

265

Generalized Beta Mixtures of Gaussians  

PubMed Central

In recent years, a rich variety of shrinkage priors have been proposed that have great promise in addressing massive regression problems. In general, these new priors can be expressed as scale mixtures of normals, but have more complex forms and better properties than traditional Cauchy and double exponential priors. We first propose a new class of normal scale mixtures through a novel generalized beta distribution that encompasses many interesting priors as special cases. This encompassing framework should prove useful in comparing competing priors, considering properties and revealing close connections. We then develop a class of variational Bayes approximations through the new hierarchy presented that will scale more efficiently to the types of truly massive data sets that are now encountered routinely. PMID:25364213

Armagan, Artin; Dunson, David B.; Clyde, Merlise

2012-01-01

266

SOLVENT EXTRACTION OF ORGANIC WATER POLLUTANTS  

EPA Science Inventory

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

267

Variable mixture ratio performance through nitrogen augmentation  

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

268

Mixtures of Linear Subspaces for Face Detection  

Microsoft Academic Search

We present two methods using mixtures of linearsubspaces for face detection in gray level images. Onemethod uses a mixture of factor analyzers to concurrentlyperform clustering and, within each cluster,perform local dimensionality reduction. The parametersof the mixture model are estimated using anEM algorithm. A face is detected if the probabilityof an input sample is above a predened threshold.The other mixture of

Ming-hsuan Yang

1999-01-01

269

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

PubMed Central

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

Cowin, Stephen C.; Cardoso, Luis

2011-01-01

270

Improved Stability of Solid Mixture Nanoparticles  

E-print Network

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

Petta, Jason

271

Face Detection Using Mixtures of Linear Subspaces  

Microsoft Academic Search

We present two methods using mixtures of linear sub- spaces for face detection in gray level images. One method uses a mixture of factor analyzers to concurrently perform clustering and, within each cluster, perform local dimen- sionality reduction. The parameters of the mixture model are estimated using an EM algorithm. A face is detected if the probability of an input

Ming-hsuan Yang; Narendra Ahuja; David J. Kriegman

2000-01-01

272

Method of photocatalytic conversion of C-H organics  

DOEpatents

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

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

1998-01-01

273

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

274

Perturbation theory based equation of state for polar molecular fluids: II. Fluid mixtures  

NASA Astrophysics Data System (ADS)

The equation of state (EOS) for 98 pure organic and inorganic fluids formulated by Churakov and Gottschalk (2003) is extended to complex fluid mixtures. For the calculation of the thermodynamic properties of mixtures, theoretical combining rules from statistical mechanics are used. These mixing rules do not involve any empirical parameters. The properties of the fluid mixtures are directly derived from those of the pure constituents. As an example we show that the EOS describes accurately the thermodynamic relations in the H 2O-CO 2 binary at high pressures and temperatures. At subcritical conditions the EOS is able to reproduce accurately the phase relations within mixtures of non-polar fluids. In particular the EOS predicts phase separations within various fluid mixtures of polar and non-polar molecules.

Churakov, S. V.; Gottschalk, M.

2003-07-01

275

On the consistency of the maximum likelyhood estimate of normal mixture parameters for a sample with field structure  

NASA Technical Reports Server (NTRS)

General theorems concerning the strong consistency of the MLE of exponential mixture parameters are proved. These theorems imply the strong consistency of the MLE of normal mixture parameters when the data is organized into fields each of which is a random sample from one of the component normal distributions.

Peters, C.

1979-01-01

276

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

PubMed Central

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

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

2002-01-01

277

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

278

Effect of Cement on Emulsified Asphalt Mixtures  

NASA Astrophysics Data System (ADS)

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

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

2007-10-01

279

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

280

Delignification of wheat straw using a mixture of carboxylic acids and peroxoacids  

Microsoft Academic Search

Wheat straw was pulping by an Organosolv process using a mixture of acetic acid\\/formic acid\\/water (AA\\/FA\\/water). In order to make easier the bleaching step, it was possible to improve the delignification in an efficient and selective manner by using peroxoacids in acidic organic medium. First a solution of peroxoacids was synthesized by adding hydrogen peroxide in a mixture of acetic

Long Kham; Yves Le Bigot; Michel Delmas; Gérard Avignon

2005-01-01

281

Development and optimization of methodologies for analysis of complex hydrocarbon mixtures. Summary of progress, 1 January-31 August, 1980  

SciTech Connect

This progress report describes studies designed to explore and to clarify the a priori prediction of optimum conditions for the chromatographic separation of complex mixtures of organic compounds of significance to the Department of Energy.

Laub, R.J.

1980-01-01

282

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

SciTech Connect

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

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

1992-04-01

283

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

SciTech Connect

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

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

1992-04-01

284

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

SciTech Connect

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

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

2009-05-01

285

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

PubMed

The combination of chemoinformatics approaches with NMR techniques and the increasing availability of data allow the resolution of problems far beyond the original application of NMR in structure elucidation/verification. The diversity of applications can range from process monitoring, metabolic profiling, authentication of products, to quality control. An application related to the automatic analysis of complex mixtures concerns mixtures of chemical reactions. We encoded mixtures of chemical reactions with the difference between the (1)H NMR spectra of the products and the reactants. All the signals arising from all the reactants of the co-occurring reactions were taken together (a simulated spectrum of the mixture of reactants) and the same was done for products. The difference spectrum is taken as the representation of the mixture of chemical reactions. A data set of 181 chemical reactions was used, each reaction manually assigned to one of 6 types. From this dataset, we simulated mixtures where two reactions of different types would occur simultaneously. Automatic learning methods were trained to classify the reactions occurring in a mixture from the (1)H NMR-based descriptor of the mixture. Unsupervised learning methods (self-organizing maps) produced a reasonable clustering of the mixtures by reaction type, and allowed the correct classification of 80% and 63% of the mixtures in two independent test sets of different similarity to the training set. With random forests (RF), the percentage of correct classifications was increased to 99% and 80% for the same test sets. The RF probability associated to the predictions yielded a robust indication of their reliability. This study demonstrates the possibility of applying machine learning methods to automatically identify types of co-occurring chemical reactions from NMR data. Using no explicit structural information about the reactions participants, reaction elucidation is performed without structure elucidation of the molecules in the mixtures. PMID:24551112

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

2014-01-01

286

Mixture distributions in human genetics research.  

PubMed

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

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

1996-06-01

287

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

288

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.

289

Centrifugal separation of a mixture  

NASA Astrophysics Data System (ADS)

In this review, we shall present a survey about recent developments in the understanding of the separation of a mixture in a rotating vessel. Based on the first principles of fluid dynamics and earlier substantial results concerned with gravity settling, recently a great variety of investigations has been published for different centrifugal devices and ranges of parameters. We shall summarize the results and provide a general view about their validity and practical applications. Finally, we shall outline possibilities for further theoretical and experimental research that is stimulated by new phenomena. Even though the theoretical results are restricted to monodisperse, Newtonian suspensions, consisting of small spherical particles freely suspended in a clear fluid, and bulk settling, the results and the physical insight gained can be applied to many industrial problems like continuous separation and filtration in centrifuges.

Schaflinger, Uwe

1990-12-01

290

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

291

The Analysis of Ethnic Mixtures  

PubMed Central

Populations of ethnic mixtures can be useful in genetic studies. Admixture mapping, or mapping by admixture linkage disequilibrium (MALD), is specially developed for admixed populations and can supplement traditional genome-wide association analyses in the search for genetic variants underlying complex traits. Admixture mapping tests the association between a trait and locus-specific ancestries. The locus-specific ancestries are in linkage disequilibrium (LD) which is generated by the admixture process between genetically distinct ancestral populations. Because of highly correlated locus-specific ancestries, admixture mapping performs many fewer independent tests across the genome than current genome-wide association analysis. Therefore, admixture mapping can be more powerful because of the smaller penalty due to multiple tests. In this chapter, I introduce the theory behind admixture mapping and how we conduct the analysis in practice. PMID:22307714

Zhu, Xiaofeng

2013-01-01

292

Polymorphic changes in mixtures of confectionery fats  

Microsoft Academic Search

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

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

1976-01-01

293

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

PubMed

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

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

2009-01-01

294

Time-dependence in mixture toxicity prediction.  

PubMed

The value of time-dependent toxicity (TDT) data in predicting mixture toxicity was examined. Single chemical (A and B) and mixture (A+B) toxicity tests using Microtox(®) were conducted with inhibition of bioluminescence (Vibrio fischeri) being quantified after 15, 30 and 45-min of exposure. Single chemical and mixture tests for 25 sham (A1:A2) and 125 true (A:B) combinations had a minimum of seven duplicated concentrations with a duplicated control treatment for each test. Concentration/response (x/y) data were fitted to sigmoid curves using the five-parameter logistic minus one parameter (5PL-1P) function, from which slope, EC25, EC50, EC75, asymmetry, maximum effect, and r(2) values were obtained for each chemical and mixture at each exposure duration. Toxicity data were used to calculate percentage-based TDT values for each individual chemical and mixture of each combination. Predicted TDT values for each mixture were calculated by averaging the TDT values of the individual components and regressed against the observed TDT values obtained in testing, resulting in strong correlations for both sham (r(2)=0.989, n=25) and true mixtures (r(2)=0.944, n=125). Additionally, regression analyses confirmed that observed mixture TDT values calculated for the 50% effect level were somewhat better correlated with predicted mixture TDT values than at the 25 and 75% effect levels. Single chemical and mixture TDT values were classified into five levels in order to discern trends. The results suggested that the ability to predict mixture TDT by averaging the TDT of the single agents was modestly reduced when one agent of the combination had a positive TDT value and the other had a minimal or negative TDT value. PMID:25446331

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

2014-12-01

295

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

296

Separation of copper from aqueous sulfate solutions by mixtures of Cyanex 301 and LIX 984N.  

PubMed

The extraction equilibria of copper(II) with Cyanex 301, LIX 984N, and their mixtures have been investigated. Extraction was studied as a function of organic phase composition, sulfuric acid concentration, pH, temperature, initial copper concentration, mixing speed, and aqueous/organic volume ratio. Considerable synergistic enhancement has been observed in the extraction of Cu(2+) with mixtures of Cyanex 301 and LIX 984N. The results demonstrate that copper ion is extracted as CuRL(2)H with synergistic mixture. The thermodynamic parameter, enthalpy change (Delta H) of Cyanex 301, LIX 984N, and their mixtures have been determined and the endothermic process has been found. The synergistic enhancement factor of copper(II) with mixtures is higher at more acidic solutions, which suggests that it is a promising synergistic extraction system for the separation of copper(II) from more acidic medium. HCl was found to be more efficient for copper stripping from loaded synergistic mixtures. PMID:19135784

Fouad, E A

2009-07-30

297

Thermodynamic behavior of supercritical fluid mixtures  

Microsoft Academic Search

The recent surge of interest in supercritical extraction has brought the unusual properties of supercritical mixtures into the focus of attention. We discuss some of the properties of binary mixtures in a range around the gas-liquid critical line from the point of view of supercritical solubility. The general thermodynamic relationships that govern the enhancement of supercritical solubility are readily derived

J. M. H. Levelt Sengers; G. Morrison; G. Nielson; R. F. Chang; C. M. Everhart; H. J. M. Hauley; A. Cezairliyan

1986-01-01

298

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

299

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...

300

COMPLEX MIXTURES AND GROUND WATER QUALITY  

EPA Science Inventory

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

301

Probabilistic expert systems for DNA mixture profiling  

Microsoft Academic Search

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

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

2003-01-01

302

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

303

21 CFR 82.6 - Certifiable mixtures.  

Code of Federal Regulations, 2013 CFR

...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 quantity of not more...

2013-04-01

304

21 CFR 82.6 - Certifiable mixtures.  

Code of Federal Regulations, 2014 CFR

...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 quantity of not more...

2014-04-01

305

21 CFR 82.6 - Certifiable mixtures.  

Code of Federal Regulations, 2012 CFR

...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 quantity of not more...

2012-04-01

306

21 CFR 82.6 - Certifiable mixtures.  

Code of Federal Regulations, 2011 CFR

...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 quantity of not more...

2011-04-01

307

21 CFR 82.6 - Certifiable mixtures.  

Code of Federal Regulations, 2010 CFR

...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 quantity of not more...

2010-04-01

308

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

309

Estimation of quantum finite mixtures  

E-print Network

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.

J. I. de Vicente; J. Calsamiglia; R. Munoz-Tapia; E. Bagan

2010-02-01

310

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...

311

Prediction of viscosity of dense fluid mixtures  

NASA Astrophysics Data System (ADS)

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

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

312

Relativistic mixtures of charged and uncharged particles  

NASA Astrophysics Data System (ADS)

Mixtures of relativistic gases within the framework of Boltzmann equation are analyzed. Three systems are considered. The first one refers to a mixture of uncharged particles by using Grad's moment method, where the relativistic mixture is characterized by the moments of the distribution functions: particle four-flows, energy-momentum tensors, and third-order moment tensors. In the second Fick's law for a mixture of relativistic gases of non-disparate rest masses in a Schwarzschild metric are derived from an extension of Marle and McCormack model equations applied to a relativistic truncated Grad's distribution function, where it is shown the dependence of the diffusion coefficient on the gravitational potential. The third one consists in the derivation of the relativistic laws of Ohm and Fourier for a binary mixtures of electrons with protons and electrons with photons subjected to external electromagnetic fields and in presence of gravitational fields by using the Anderson and Witting model of the Boltzmann equation.

Kremer, Gilberto M.

2014-01-01

313

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

314

Ionic liquid/water mixtures: from hostility to conciliation.  

PubMed

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

Kohno, Yuki; Ohno, Hiroyuki

2012-07-21

315

Genotoxicity of complex mixtures: CHO cell mutagenicity assay  

SciTech Connect

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

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

1985-02-01

316

Correlating Thermal-Conductivity Data for Ternary Liquid Mixtures  

NASA Astrophysics Data System (ADS)

The performance of several semi-empirical expressions for correlating the temperature, pressure and composition dependence of the thermal conductivity (?) of pure organic liquids and mixtures was investigated. The temperature and pressure dependence is adequately represented by Chisholm approximants of order (1, 1) or (2, 1) with five and eight adjustable constants, respectively. The fully predictive Vredeveld equation uses mass fractions as the composition variable. It significantly underestimated ? values for the R32 + R125 + R134a ternary refrigerant system. Binary predictive models with one or two adjustable parameters include the quadratic Scheffé polynomial and its corresponding Padé approximant, the cubic “Margules” model and the theoretical Wassiljewa equation. It was found that the Padé (2, 2) approximant and the Wassiljewa equation satisfactorily correlated the extensive ternary mixture data published by Rowley and coworkers. Best results were obtained when the mole fraction was used as a composition variable. The predictive capability of the models was checked using the R32 + R125 + R134a ternary refrigerant system. Combining rules were used for cross parameters such that the temperature and pressure dependence was incorporated via the pure fluid properties. Model parameters were fixed using binary data alone. In this case, the quadratic Scheffé, Padé (2, 2), and Wassiljewa (with temperature- and pressure-independent parameters) all provided satisfactory predictions for ternary mixtures.

Focke, Walter W.

2008-08-01

317

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

SciTech Connect

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 oxygenated gasoline in the subsurface, the dissolution of diesel fuel and coal-tar, and the use of chemical agents such as surfactants or solvents to enhance the removal of contaminants by pump-and-treat remediation. A discussion of these few selected examples will serve to highlight some of the issues associated with complex mixtures, with a focus on potential groundwater contamination and remediation.

Brusseau, M.L.

1993-05-01

318

Reproducibility of binary-mixture toxicity studies.  

PubMed

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

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

2007-01-01

319

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

320

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

321

Separation of gas mixtures using Co(II) carborane-based porous coordination polymersw  

E-print Network

Separation of gas mixtures using Co(II) carborane-based porous coordination polymersw Youn-Sang Bae adsorption.1 Porous coordination polymers (PCPs), also referred to as metal­organic frameworks (MOFs collapse under harsh conditions.4 To this end, we recently introduced an example of Co(II) carborane-based

322

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

NASA Technical Reports Server (NTRS)

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

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

1969-01-01

323

ISOLATION OF ORGANIC WATER POLLUTANTS BY XAD RESINS AND CARBON  

EPA Science Inventory

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

324

Hierarchical Mixtures of Experts and the EM Algorithm  

E-print Network

We present a tree-structured architecture for supervised learning. The statistical model underlying the architecture is a hierarchical mixture model in which both the mixture coefficients and the mixture components are ...

Jordan, Michael I.

1993-08-01

325

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

326

Transcriptional responses indicate attenuated oxidative stress in the springtail Folsomia candida exposed to mixtures of cadmium and phenanthrene.  

PubMed

Since the 'omics revolution', the assessment of toxic chemical mixtures has incorporated approaches where phenotypic endpoints are connected to a mechanistic understanding of toxicity. In this study we determined the effect of binary mixtures of cadmium and phenanthrene on the reproduction of Folsomia candida and investigated the cellular mechanisms underlying this response. Mixture toxicity modeling showed an antagonistic deviation from concentration addition for reproduction effects of the mixtures. Subsequent transcriptional response analysis was done using five mixtures at the modeled 50 % effect level for reproduction. The transcription profiles of 86 high throughput RT-qPCR assays were studied by means of partial least squares regression analysis. The first and second principal components (PCs) were correlated with global responses to cadmium and phenanthrene, while correlations with the mixture treatments were found in the higher PCs. Specifically associated with the mixture treatments were a biotransformation phase II gene, four mitochondrial related genes and a gene involved in the biosynthesis of antioxidant selenoproteins. Membrane integrity related gene inductions were correlated with the single phenanthrene treatment but not with the mixtures. Immune and inflammatory response assays did not correlate with any of the mixtures. These results suggest moderated oxidative stress, a higher mitochondrial maintenance and less compromised membrane function in the mixture exposed samples compared to the separate cadmium or phenanthrene exposures. The antagonism found for inhibition of reproduction may partially originate from these differences. Mechanistic studies on mixture toxicity can ultimately aid risk assessment by defining relevant toxicity pathways in organisms exposed to real-world mixture exposures present in the field. PMID:23483327

de Boer, Muriel E; Ellers, Jacintha; van Gestel, Cornelis A M; den Dunnen, Johan T; van Straalen, Nico M; Roelofs, Dick

2013-05-01

327

Vortices in condensate mixtures Christophe Josserand  

E-print Network

su- perfluidity. Mixtures of Helium 4 and 3 (a Fermion) can remain liquid, although the spin effects in Helium 3 make the whole picture quite different, but certainly extremely interesting from the present

328

Industrial Utilization of Coal-Oil Mixtures  

E-print Network

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

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

1982-01-01

329

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...

330

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

331

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

332

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...

333

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

334

PVT measurements for five natural gas mixtures  

E-print Network

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

Simon, Philip Parayil

1991-01-01

335

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

336

Interfacial tension of a decomposed biopolymer mixture  

Microsoft Academic Search

Many biological systems as well as food products contain both proteins and polysaccharides, which are\\u000aoften thermodynamically incompatible. In this communication,measurementsare presented of the interfacial\\u000atension in a segregated polysaccharide\\/protein mixture. The interfacial tension is an important quantity\\u000ain determining the phase separation kinetics and the response to shear. As the protein\\/polysaccharide\\u000asystem, an aqueous gelatin\\/dextran mixture in 1.0 M

E. Scholten; R. Tuinier; R. H. Tromp; H. N. W. Lekkerkerker

2002-01-01

337

Predicting the viscosity of halogenated hydrocarbon mixtures  

Microsoft Academic Search

The viscosity of three refrigerant mixtures, namely R125–R134a, R152a–R134a and propane–R134a, has been evaluated by a prediction method based on kinetic theory. The method has no adjustable parameters and, in essence, relies upon knowledge of the viscosity of the pure components to predict the viscosity of a mixture by means of rigid-sphere formalism. The predictions have been compared with experimental

V. Vesovic

2002-01-01

338

Flash evaporation of liquid monomer particle mixture  

DOEpatents

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

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

1999-05-11

339

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

340

Speaker Verification Using Adapted Gaussian Mixture Models  

Microsoft Academic Search

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

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

2000-01-01

341

Estimating Location Parameters in a Mixture Model  

NASA Technical Reports Server (NTRS)

Mixture models of the form h = sum to M terms, one for each positive integer from 1 to N lambda sub j f (j) sub theta sub j where theta sub j is a translation parameter are considered. An approach is discussed which makes use of a Caratheodory theorem on the trigonometric moment problem to determine M and theta sub j j = 1,2,...,M. This theorem is also applied to show that translates of many common distributions lead to identifiable mixtures.

Heydorn, R. P.; Basu, R.

1983-01-01

342

Thermodynamics of wax precipitation in petroleum mixtures  

SciTech Connect

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

Firoozabadi, A.; Lira-Galeana, C.L. [Reservoir Engineering Research Institute, Palo Alto, CA (United States); Prausnitz, J.M. [Univ. of California, Berkeley, CA (United States)

1995-12-01

343

Thermodynamics of wax precipitation in petroleum mixtures  

SciTech Connect

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

Lira-Galeana, C.; Firoozabadi, A. [Reservoir Engineering Research Inst., Palo Alto, CA (United States)] [Reservoir Engineering Research Inst., Palo Alto, CA (United States); Prausnitz, J.M. [Univ. of California, Berkeley, CA (United States). Chemical Engineering Dept.] [Univ. of California, Berkeley, CA (United States). Chemical Engineering Dept.; [Lawrence Berkeley Lab., CA (United States). Chemical Sciences Div.

1996-01-01

344

Thermal conductivity of nanoparticle-fluid mixture  

Microsoft Academic Search

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

X. Wang; Xianfan Xu

1999-01-01

345

Toxicity evaluation of PAH mixtures using Microtox  

SciTech Connect

Polycyclic aromatic hydrocarbons (PAH) are produced from both natural and anthropogenic combustion processes. PAHs are known to be toxic and carcinogenic, are prevalent at many hazardous waste sites, and pose a potential risk to both ecological and human health. To date, few researchers have assessed the toxicity of polycyclic aromatic hydrocarbon (PAH) mixtures. The toxicity of chrysene, anthracene, pyrene, phenanthrene, fluoranthrene, acenaphthene, fluorene, and naphthalene were evaluated using Microtox, and acute toxicity assay that uses bioluminescent bacteria, Photobacterium phosphoreum, to measure toxicity. In this study, the toxicities of 2, 3, and 4 ring PAHs were determined for individual compounds. Synergistic or additive effects of PAH mixtures was assessed by comparing the toxicity of mixtures with that of pure compounds. Each PAH or mixture was evaluated at their respective water solubility concentrations, For individual PAHs tested, the toxicity of PAHs is inversely related to water solubility. Mixtures of two and three PAHs with disparate water solubilities resulted in synergistic interactions. Antagonistic interactions, a decrease in toxicity, were observed for mixtures of similar water solubilities.

Thompkins, J.; Guthrie, E.; Pfaender, F. [Univ. of North Carolina, Chapel Hill, NC (United States)

1995-12-31

346

Variational Theory of Mixtures in Continuum Mechanics  

E-print Network

In continuum mechanics, the equations of motion for mixtures are derived through the use of Hamilton's extended principle which regards the mixture as a collection of distinct continua. The internal energy is assumed to be a function of densities, entropies and successive spatial gradients of each constituent. We first write the equations of motion for each constituent of an inviscid miscible mixture of fluids without chemical reactions or diffusion. Our work leads to the equations of motion in an universal thermodynamic form in which interaction terms subject to constitutive laws, difficult to interpret physically, do not occur. For an internal energy function of densities, entropies and spatial gradients, an equation describing the barycentric motion of the constituents is obtained. The result is extended for dissipative mixtures and an equation of energy is obtained. A form of Clausius-Duhem's inequality which represents the second law of thermodynamics is deduced. In the particular case of compressible mixtures, the equations reproduce the classical results. Far from critical conditions, the interfaces between different phases in a mixture of fluids are layers with strong gradients of density and entropy. The surface tension of such interfaces is interpreted.

Henri Gouin

2008-07-28

347

Assessing the Biological Potency of Binary Mixtures of Environmental  

E-print Network

Assessing the Biological Potency of Binary Mixtures of Environmental Estrogens using Vitellogenin conducted to assess the in vivo potency of binary mixtures of estrogenic chemicals using plasma vitellogenin

Tyler, Charles

348

Organic spintronics  

Microsoft Academic Search

We review the emerging field of organic spintronics, where organic materials are applied as a medium to transport and control spin-polarized signals. The contacts for injecting and detecting spins are formed by ferromagnetic metals, oxides, or inorganic semiconductors. First, the basic concepts of spintronics and organic electronics are addressed, and phenomena which are in particular relevant for organic spintronics are

W. J. M. Naber; S. Faez; W. G. van der Wiel

2007-01-01

349

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

PubMed

Minimum ignition energies (MIE) of ?-pinene-benzene/air mixtures at a given temperature for different equivalence ratios and fuel proportions are experimented in this paper. We used a cylindrical chamber of combustion using a nanosecond pulse at 1064nm from a Q-switched Nd:YAG laser. Laser-induced spark ignitions were studied for two molar proportions of ?-pinene/benzene mixtures, respectively 20-80% and 50-50%. The effect of the equivalence ratio (?) has been investigated for 0.7, 0.9, 1.1 and 1.5 and ignition of fuel/air mixtures has been experimented for two different incident laser energies: 25 and 33mJ. This study aims at observing the influence of different ?-pinene/benzene proportions on the flammability of the mixture to have further knowledge of the potential of biogenic volatile organic compounds (BVOCs) and smoke mixtures to influence forest fires, especially in the case of the accelerating forest fire phenomenon (AFF). Results of ignition probability and energy absorption are based on 400 laser shots for each studied fuel proportions. MIE results as functions of equivalence ratio compared to data of pure ?-pinene and pure benzene demonstrate that the presence of benzene in ?-pinene-air mixture tends to increase ignition probability and reduce MIE without depending strongly on the ?-pinene/benzene proportion. PMID:25464289

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

2015-02-11

350

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

PubMed Central

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

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

2013-01-01

351

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

PubMed

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

Farley, Kevin J; Meyer, Joseph S

2014-12-01

352

Mixture modeling of microarray gene expression data  

PubMed Central

About 28% of genes appear to have an expression pattern that follows a mixture distribution. We use first- and second-order partial correlation coefficients to identify trios and quartets of non-sex-linked genes that are highly associated and that are also mixtures. We identified 18 trio and 35 quartet mixtures and evaluated their mixture distribution concordance. Concordance was defined as the proportion of observations that simultaneously fall in the component with the higher mean or simultaneously in the component with the lower mean based on their Bayesian posterior probabilities. These trios and quartets have a concordance rate greater than 80%. There are 33 genes involved in these trios and quartets. A factor analysis with varimax rotation identifies three gene groups based on their factor loadings. One group of 18 genes has a concordance rate of 56.7%, another group of 8 genes has a concordance rate of 60.8%, and a third group of 7 genes has a concordance rate of 69.6%. Each of these rates is highly significant, suggesting that there may be strong biological underpinnings for the mixture mechanisms of these genes. Bayesian factor screening confirms this hypothesis by identifying six single-nucleotide polymorphisms that are significantly associated with the expression phenotypes of the five most concordant genes in the first group. PMID:18466550

Yang, Yang; Tashman, Adam P; Lee, Jung Yeon; Yoon, Seungtai; Mao, Wenyang; Ahn, Kwangmi; Kim, Wonkuk; Mendell, Nancy R; Gordon, Derek; Finch, Stephen J

2007-01-01

353

Mixtures of Receiver Operating Characteristic Curves  

PubMed Central

Rationale and Objectives ROC curves are ubiquitous in the analysis of imaging metrics as markers of both diagnosis and prognosis. While empirical estimation of ROC curves remains the most popular method, there are several reasons to consider smooth estimates based on a parametric model. Materials and Methods A mixture model is considered for modeling the distribution of the marker in the diseased population motivated by the biological observation that there is more heterogeneity in the diseased population than there is in the normal one. It is shown that this model results in an analytically tractable ROC curve which is itself a mixture of ROC curves. Results The use of CK-BB isoenzyme in diagnosis of severe head trauma is used as an example. ROC curves are fit using the direct binormal method, ROCKIT and the Box-Cox transformation as well as the proposed mixture model. The mixture model generates an ROC curve that is much closer to the empirical one than the other methods considered. Conclusions Mixtures of ROC curves can be helpful in fitting smooth ROC curves in datasets where the diseased population has higher variability than can be explained by a single distribution. PMID:23643788

Gönen, Mithat

2014-01-01

354

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

355

Relativistic mixtures of charged and uncharged particles  

SciTech Connect

Mixtures of relativistic gases within the framework of Boltzmann equation are analyzed. Three systems are considered. The first one refers to a mixture of uncharged particles by using Grad’s moment method, where the relativistic mixture is characterized by the moments of the distribution functions: particle four-flows, energy-momentum tensors, and third-order moment tensors. In the second Fick’s law for a mixture of relativistic gases of non-disparate rest masses in a Schwarzschild metric are derived from an extension of Marle and McCormack model equations applied to a relativistic truncated Grad’s distribution function, where it is shown the dependence of the diffusion coefficient on the gravitational potential. The third one consists in the derivation of the relativistic laws of Ohm and Fourier for a binary mixtures of electrons with protons and electrons with photons subjected to external electromagnetic fields and in presence of gravitational fields by using the Anderson and Witting model of the Boltzmann equation.

Kremer, Gilberto M. [Departamento de Física, Universidade Federal do Paraná, Curitiba (Brazil)

2014-01-14

356

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

357

ADDITIVITY ASSESSMENT OF TRIHALOMETHANE MIXTURES BY PROPORTIONAL RESPONSE ADDITION  

EPA Science Inventory

If additivity is known or assumed, the toxicity of a chemical mixture may be predicted from the dose response curves of the individual chemicals comprising the mixture. As single chemical data are abundant and mixture data sparse, mixture risk methods that utilize single chemical...

358

Brief report on primary mixture preparation for precise CO observation  

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

359

Heat exchanger analysis for nonazeotropic refrigerant mixtures  

SciTech Connect

A fundamental method for analyzing heat exchangers using pure refrigerants and nonazeotropic refrigerant mixtures is presented. The method allows for calculation of heat and mass transfer between moist air and nonazeotropic refrigerant mixtures and predicts local parameters of air and mixtures. Both single and two phase refrigerants can be analyzed with this method. Algorithms for the use of this model are presented. Data and calculated thermal performance for two conventional types of air-side geometries are also presented. The algorithms to calculate thermal performance of heat exchangers can be used for either conventional or enhanced geometries. A comparison of crossflow, cross-counterflow, and counterflow heat exchangers is given. The algorithms are sufficient for design and development of equipment using pure and mixed refrigerants.

Poz, M.Y. [Russian Association of Engineers for Heating, Ventilation, Air Conditioning, Heat Supply and Building Thermal Physics (ABOK), Moscow (Russian Federation); Conklin, J.C. [Oak Ridge National Lab., TN (United States)

1994-02-01

360

Near critical phase behaviour of dilute mixtures  

NASA Astrophysics Data System (ADS)

Predictions of the limiting phase behaviour of dilute mixtures of n-decane, n-tetradecane, n-octadecane, and n-docosane with n-hexane in the highly compressible region close to the critical point of n-hexane are presented. The predictions are based on a classical Taylor expansion of the Helmholtz energy about the critical point of the solvent [1, 2] and make use of the measured critical properties of the dilute mixtures. The importance of the Krichevskii parameter as a key factor influencing the limiting phase behaviour of dilute mixtures is demonstrated in the case of infinite dilution partition coefficients as well as solute partial molar volumes, and the link to a statistical mechanical description is made.

Gude, Michael T.; Teja, Amyn S.

361

Generalized competitive learning of gaussian mixture models.  

PubMed

When fitting Gaussian mixtures to multivariate data, it is crucial to select the appropriate number of Gaussians, which is generally referred to as the model selection problem. Under regularization theory, we aim to solve this model selection problem through developing an entropy regularized likelihood (ERL) learning on Gaussian mixtures. We further present a gradient algorithm for this ERL learning. Through some theoretic analysis, we have shown a mechanism of generalized competitive learning that is inherent in the ERL learning, which can lead to automatic model selection on Gaussian mixtures and also make our ERL learning algorithm less sensitive to the initialization as compared to the standard expectation-maximization algorithm. The experiments on simulated data using our algorithm verified our theoretic analysis. Moreover, our ERL learning algorithm has been shown to outperform other competitive learning algorithms in the application of unsupervised image segmentation. PMID:19362913

Lu, Zhiwu; Ip, Horace H S

2009-08-01

362

Mixtures of planetary ices at extreme conditions.  

PubMed

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

Lee, Mal-Soon; Scandolo, Sandro

2011-01-01

363

Detailed Kinetic Modeling of Gasoline Surrogate Mixtures  

SciTech Connect

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

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

2009-03-09

364

Electrochemical destruction of organic acids  

SciTech Connect

An electrochemical process for removing organic acids from an aqueous waste stream has been characterized. Biological treatment of aqueous organic acid waste streams has been the typical means of degrading organic acids, and the resultant biosludge is landfilled. In the electrochemical approach, aqueous organic acids may be efficiently converted to useful fuel in a one or two electron process. The possible reactions occurring are outlined here. The electrolysis of the sodium salts of acetic, propionic, and butyric acids has been studied both as single component solutions and mixtures. The reaction products as well as relative rates of destruction of the acid salts were measured. The effect of experimental variables such as current density, temperature, and anode material on the current efficiency and product distribution was investigated. Electrode stability due to platinum corrosion was identified as the major limitation to the process.

Gendes, J.D.; Hartsough, D. [Electrosynthesis Co., Inc., Lancaster, NY (United States); Super, J.D. [DuPont Specialty Chemicals, Deepwater, NJ (United States)

1994-12-31

365

Diffusion in mercury-argon gas mixtures  

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

366

Thermophysical Properties of Fluids and Fluid Mixtures  

SciTech Connect

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

Sengers, Jan V.; Anisimov, Mikhail A.

2004-05-03

367

Organic Chemistry  

NSDL National Science Digital Library

R. H. Logan, an chemistry instructor at North Lake College, created this introduction to organic chemistry. The introduction covers a eight types of organic compounds, including Alkanes, Alkyl Halides, and Acyl Compounds (forthcoming); Conformational Analysis and Stereoisomerism; and Instrumental Analysis of Organic Compounds, as well an extensive lesson in general chemistry.

368

Monitoring oil-water mixture separation by time domain reflectometry  

NASA Astrophysics Data System (ADS)

Effective separation of water and oil is an essential part of petroleum production. Time domain reflectometry (TDR) can be used to profile the separation of hydrocarbon oil-water mixtures. In such two-component systems, metal electrodes will become oil-coated due to their affinity to oil. This coating layer will impact water content measurements. By combining the TDR signals from two probes in a novel configuration, the thickness of the oil layer on the electrodes can be estimated and its effect on the TDR measurements corrected for. The probes consist of two rods of different diameter and spacing to a common ground/guard electrode. The measurement principle is demonstrated using a light fuel oil and a thicker organic oil. The results indicate that oil and water levels can be monitored during separation if the metal electrode oil-coating effect is accounted for.

Bruvik, E. M.; Hjertaker, B. T.; Folgerø, K.; Meyer, S. K.

2012-12-01

369

A method and apparatus for destroying hazardous organics and other combustible materials in a subcritical/supercritical reactor  

SciTech Connect

A waste destruction method is described 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.

1997-12-01

370

Organ History  

NSDL National Science Digital Library

Developed and maintained by Professor James H. Cook at Birmingham - Southern College, this site is an online tutorial that offers an interesting and interactive perspective of that king of all instruments, the organ. The site is divided into three main sections: The Organ and How it Works, Organ History, and Geographical Tour. In the first section, visitors are taken through a basic description of an organ, which then continues into a discussion of the various parts of an organ, such as the keyboards, consoles, pipes, chests, cases, and chambers. The history section begins with the invention of what is commonly understood to be the first organ, the ktseibios, built by a Greek engineer working in the third century BCE. The final section takes visitors on a chronological tour of the organ and its development throughout a number of countries, including England, France, Germany, Italy, and the United States.

Cook, James H.

371

Natural hybrid organic–inorganic photovoltaic devices  

Microsoft Academic Search

Natural hybrid organic–inorganic photovoltaic devices based on TiO2 have been realized. Chlorophyll A (from anacystis nidulans algae), chlorophyll B (from spinach), carmic acid (from insect Coccus cacti L.), synthetic trans-?-carotene, natural fresh picked Morus nigra, and their mixtures have been used as an organic photo active layer to fabricate photovoltaic prototypes. In order to reduce the charge’s interfacial recombination, different thicknesses

Paola De Padova; Massimiliano Lucci; Bruno Olivieri; Claudio Quaresima; Sandro Priori; Roberto Francini; Antonio Grilli; Karol Hricovini; Ivan Davoli

2009-01-01

372

Polypropylene - asphalt mixtures for waterproofing membranes  

Microsoft Academic Search

In any field of polymer-asphalt mixtures application is extremely important to achieve a very good compatibility between the components in order to improve as much as possible the performances due to the polymer content. In the case of waterproofing membranes application this compatibility reduce, moreover, the amount of polymer required to obtain the best performances. Using the Colloidal Instability Index

P. Italia; E. Brandolese

1996-01-01

373

Optimization of endmembers for spectral mixture analysis  

Microsoft Academic Search

Linear spectral mixture analysis can be used to model the spectral variability in multi- or h yperspectral images and to relate the results to the physical abundance of surface constituents represented by the spectral endmembers. The most difficult step in. this analytical approach lies in the selection of spectral endmembers, which are chosen to represent surface components. A new approach

Stefanie Tompkins; John F. Mustard; Carle M. Pieters; Donald W. Forsyth

1997-01-01

374

Removal of COâ from gas mixtures  

Microsoft Academic Search

An improved, catalyzed process for the removal of COâ from gas mixtures is described using a solution containing 15-40% by weight of potassium carbonate in which the absorption efficiency is enhanced by the addition of sodium or potassium vanadate equivalent to 2 to 10% by weight of VâOâ and sodium or potassium borate equivalent to 1 to 10% by weight

Eickmeyer

1984-01-01

375

Modeling the chemistry of complex petroleum mixtures.  

PubMed

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

Quann, R J

1998-12-01

376

Mixture Models for Capture-Recapture Data  

E-print Network

between TheoryMixture Models between Theory and Applicationsand Applications" Rome, September 13, 2002 #12 such as age at diagnosis, gender, .. #12;... in more detail ID Source A Source B Source C Counting Sources 001 of development ... illustrated with 3 sources · modelling a multiway contingeny table · modelling the counting

Boehning, Dankmar

377

Non-equilibrium properties of hadronic mixtures  

Microsoft Academic Search

The equilibration of hot hadronic matter is studied in the framework of relativistic kinetic theory. Various non-equilibrium properties of a mixture comprised of pions, kaons and nucleons are calculated in the dilute limit for small deviations from local thermal equilibrium. Interactions between these constituents are specified through the empirical phase shifts. The properties calculated include the relaxation\\/collision times, momentum and

Madappa Prakash; Manju Prakash; Raju Venugopalan; Gerd Welke

1993-01-01

378

Theoretical Thermodynamics of Mixtures at High Pressures  

NASA Technical Reports Server (NTRS)

The development of an understanding of the chemistry of mixtures of metallic hydrogen and abundant, higher-z material such as oxygen, carbon, etc., is important for understanding of fundamental processes of energy release, differentiation, and development of atmospheric abundances in the Jovian planets. It provides a significant theoretical base for the interpretation of atmospheric elemental abundances to be provided by atmospheric entry probes in coming years. Significant differences are found when non-perturbative approaches such as Thomas-Fermi-Dirac (TFD) theory are used. Mapping of the phase diagrams of such binary mixtures in the pressure range from approx. 10 Mbar to approx. 1000 Mbar, using results from three-dimensional TFD calculations is undertaken. Derivation of a general and flexible thermodynamic model for such binary mixtures in the relevant pressure range was facilitated by the following breakthrough: there exists an accurate nd fairly simple thermodynamic representation of a liquid two-component plasma (TCP) in which the Helmholtz free energy is represented as a suitable linear combination of terms dependent only on density and terms which depend only on the ion coupling parameter. It is found that the crystal energies of mixtures of H-He, H-C, and H-O can be satisfactorily reproduced by the same type of model, except that an effective, density-dependent ionic charge must be used in place of the actual total ionic charge.

Hubbard, W. B.

1985-01-01

379

Classification of Material Mixtures in Volume Data  

E-print Network

to compute the relative proportion of each material in the voxels. Other classification methods have utilized.g. computational fluid dynamics (CFD) and finite element method (FEM) simulations. MRI is of particular interest the materials are mixed together. We extend this approach by deriving non­Gaussian ``mixture'' basis functions

380

Classification of Material Mixtures in Volume Data  

E-print Network

to compute the relative proportion of each material in the voxels. Other classification methods have utilized.g. computational fluid dynamics (CFD) and finite element method (FEM) simulations. MRI is of particular interest the materials are mixed together. We extend this approach by deriving non-Gaussian "mixture" basis functions. We

381

Extended Object Tracking Using Mixture Kalman Filtering  

E-print Network

, Bulgaria donka@bas.bg 2 Department of Communication Systems, Lancaster University, South Drive, Lancaster that the unknown shape parameters are defined over the discrete set of values, a data augmentation (DA) algorithm is basically an iterative procedure. In this paper we propose an alternative solution, using a mixture Kalman

Mihaylova, Lyudmila

382

Superconductor precursor mixtures made by precipitation method  

DOEpatents

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

Bunker, Bruce C. (Albuquerque, NM); Lamppa, Diana L. (Albuquerque, NM); Voigt, James A. (Albuquerque, NM)

1989-01-01

383

Video Compressive Sensing Using Gaussian Mixture Models  

E-print Network

1 Video Compressive Sensing Using Gaussian Mixture Models Jianbo Yang, Xin Yuan, Xuejun Liao) based algorithm is proposed for video reconstruction from temporally-compressed video measurements. The GMM is used to model spatio-temporal video patches, and the reconstruction can be efficiently computed

Carin, Lawrence

384

TOXICOLOGY OF COMPLEX MIXTURES OF INDOOR AIR  

EPA Science Inventory

This review focuses on strategies for assessing the toxicology of indoor air pollutant mixtures. hese strategies are illustrated by reviewing the current problems and approaches to the toxicology of indoor air pollutants from three indoor source categories which make a major cont...

385

Biosurfactant-enhanced solubilization of NAPL mixtures  

NASA Astrophysics Data System (ADS)

Remediation of nonaqueous phase liquids (NAPLs) by conventional pump-and-treat methods (i.e., water flushing) is generally considered to be ineffective due to low water solubilities of NAPLs and to mass-transfer constraints. Chemical flushing techniques, such as surfactant flushing, can greatly improve NAPL remediation primarily by increasing the apparent solubility of NAPL contaminants. NAPLs at hazardous waste sites are often complex mixtures. However, the equilibrium and nonequilibrium mass-transfer characteristics between NAPL mixtures and aqueous surfactant solutions are not well understood. This research investigates the equilibrium solubilization behavior of two- and three-component NAPL mixtures (containing akylbenzenes) in biosurfactant solutions. NAPL solubilization is found to be ideal in water (i.e., obeys Raoult's Law), while solubilization in biosurfactant solutions was observed to be nonideal. Specifically, the relatively hydrophobic compounds in the mixture experienced solubility enhancements that were greater than those predicted by ideal enhanced solubilization theory, while the solubility enhancements for the relatively hydrophilic compounds were less than predicted. The degree of nonideality is shown to be a nonlinear function of the NAPL-phase mole fraction. Empirical relationships based on the NAPL-phase mole fraction and/or micelle-aqueous partition coefficients measured in single-component NAPL systems are developed to estimate values for the multicomponent partition coefficients. Empirical relationships that incorporate both the NAPL-phase mole fraction and single-component partition coefficients yield much improved estimates for the multicomponent partition coefficient.

McCray, John E.; Bai, Guiyun; Maier, Raina M.; Brusseau, Mark L.

2001-03-01

386

HEALTH RISK ASSESSMENT OF CHEMICAL MIXTURES  

EPA Science Inventory

The implementation of Superfund requires a methodology for estimating health risk from multi-chemical contamination at ambient levels. Most often, the chemical composition of these mixtures is poorly characterized, exposure data are uncertain and toxicologic data on the known com...

387

Mixtures of Experts Estimate A Posteriori Probabilities  

E-print Network

overlaps are possible) and attributes expert networks to these di erent regions. The divideExpert 2 Figure1. Architecture of a mixture of experts network. Figure 1 shows the architecture of a ME network, consisting of three expert networks and one gating network both having access to the input vector

388

Bayesian Density Estimation and Inference Using Mixtures  

Microsoft Academic Search

We describe and illustrate Bayesian inference in models for density estimation using mixturesof Dirichlet processes. These models provide natural settings for density estimation,and are exemplified by special cases where data are modelled as a sample from mixtures ofnormal distributions. Efficient simulation methods are used to approximate various prior,posterior and predictive distributions. This allows for direct inference on a variety of

Michael D. Escobar; Mike West

1994-01-01

389

Analysis of exponential decay curves of mixtures  

E-print Network

of this research we can only conclude that Prony's method& with the modification herein, is not a satisfactory method for solving the problem of determining the components of a radio- active mixture of three elements. 1 Personal communication from Dr. Mario...

McGaughey, Robert Lee

2012-06-07

390

Characterisation of stone matrix asphalt mixtures  

Microsoft Academic Search

This study applied conventional laboratory tests and advanced imaging techniques to experimentally verify the voids in coarse aggregate (VCA) method. Five stone matrix asphalt (SMA) mixtures designed to have different coarse aggregate skeletons were investigated to establish relationships between the VCA ratio, microstructure parameters and the mechanical response of SMA. X-ray CT and image analysis techniques were utilised to non-destructively

Laith Tashman; Brian Pearson

2012-01-01

391

Characterisation of stone matrix asphalt mixtures  

Microsoft Academic Search

This study applied conventional laboratory tests and advanced imaging techniques to experimentally verify the voids in coarse aggregate (VCA) method. Five stone matrix asphalt (SMA) mixtures designed to have different coarse aggregate skeletons were investigated to establish relationships between the VCA ratio, microstructure parameters and the mechanical response of SMA. X-ray CT and image analysis techniques were utilised to non-destructively

Laith Tashman; Brian Pearson

2011-01-01

392

Automatic accent identification using Gaussian mixture models  

Microsoft Academic Search

It is well known that speaker variability caused by accent is an important factor in speech recognition. Some major accents in China are so different as to make this problem very severe. In this paper, we propose a Gaussian mixture model (GMM) based Mandarin accent identification method. In this method, a number of GMMs are trained to identify the most

Too Chen; Chao Huang; Eric Chang; Jingehan Wang

2001-01-01

393

A Skew-Normal Mixture Regression Model  

ERIC Educational Resources Information Center

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

Liu, Min; Lin, Tsung-I

2014-01-01

394

Mixture segregation by an inertial cavitation bubble  

Microsoft Academic Search

Pressure diffusion is a mass diffusion process forced by pressure gradients. It has the ability to segregate two species of a mixture, driving the densest species toward high pressure zones, but requires very large pressure gradients to become noticeable. An inertial cavitation bubble develops large pressure gradients in its vicinity, especially as the bubble rebounds at the end of its

R. Grossier; O. Louisnard; Y. Vargas

2007-01-01

395

Analysis of complex mixtures – Cigarette smoke  

Microsoft Academic Search

Mainstream cigarette smoke is a complex mixture that is inhaled into the respiratory system. The physical characteristics and chemical composition of mainstream smoke are reviewed and briefly compared with that of sidestream smoke. Special attention is paid to ageing effects and artifact formation during the sampling and testing of cigarette smoke, with specific examples of artifact formation during sampling discussed

Michael Borgerding; Hubert Klus

2005-01-01

396

Performance characteristics of organic Rankine cycles  

Microsoft Academic Search

The organic Rankine cycle is one of the most promising techniques for production of mechanical power from low temperature sources such as solar heated fluids, geothermal brines and industrial waste heat. A series of cycle performance calculations has been carried out for a broad range of working fluids including Refrigerant 12, isobutane, isopentane, propone, and toluene as well as mixtures

J. P. Lamb

1984-01-01

397

Influence of solvent on ion aggregation and transport in PY15TFSI ionic liquid-aprotic solvent mixtures.  

PubMed

Molecular dynamics (MD) simulations using a many-body polarizable APPLE&P force field have been performed on mixtures of the N-methyl-N-pentylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PY15TFSI) ionic liquid (IL) with three molecular solvents: propylene carbonate (PC), dimethyl carbonate (DMC), and acetonitrile (AN). The MD simulations predict density, viscosity, and ionic conductivity values that agree well with the experimental results. In the solvent-rich regime, the ionic conductivity of the PY15TFSI-AN mixtures was found to be significantly higher than the conductivity of the corresponding -PC and -DMC mixtures, despite the similar viscosity values obtained from both the MD simulations and experiments for the -DMC and -AN mixtures. The significantly lower conductivity of the PY15TFSI-DMC mixtures, as compared to those for PY15TFSI-AN, in the solvent-rich regime was attributed to the more extensive ion aggregation observed for the -DMC mixtures. The PY15TFSI-DMC mixtures present an interesting case where the addition of the organic solvent to the IL results in an increase in the cation-anion correlations, in contrast to what is found for the mixtures with PC and AN, where ion motion became increasingly uncorrelated with addition of solvent. A combination of pfg-NMR and conductivity measurements confirmed the MD simulation predictions. Further insight into the molecular interactions and properties was also obtained using the MD simulations by examining the solvent distribution in the IL-solvent mixtures and the mixture excess properties. PMID:23941158

Borodin, Oleg; Henderson, Wesley A; Fox, Eric T; Berman, Marc; Gobet, Mallory; Greenbaum, Steve

2013-09-12

398

Isolation of Acetobacterium sp. Strain AG, Which Reductively Debrominates Octa- and Pentabrominated Diphenyl Ether Technical Mixtures  

PubMed Central

Polybrominated diphenyl ethers (PBDEs) are a class of environmental pollutants that have been classified as persistent organic pollutants since 2009. In this study, a sediment-free enrichment culture (culture G) was found to reductively debrominate octa- and penta-BDE technical mixtures to less-brominated congeners (tetra-, tri-, and di-BDEs) via a para-dominant debromination pattern for the former and a strict para debromination pattern for the latter. Culture G could debrominate 96% of 280 nM PBDEs in an octa-BDE mixture to primarily tetra-BDEs in 21 weeks. Continuous transferring of culture G with octa-/penta-BDEs dissolved in n-nonane or trichloroethene (TCE) yielded two strains (Acetobacterium sp. strain AG and Dehalococcoides sp. strain DG) that retained debromination capabilities. In the presence of lactate but without TCE, strain AG could cometabolically debrominate 75% of 275 nM PBDEs in a penta-BDE mixture in 33 days. Strain AG shows 99% identity to its closest relative, Acetobacterium malicum. In contrast to strain AG, strain DG debrominated PBDEs only in the presence of TCE. In addition, 18 out of 19 unknown PBDE debromination products were successfully identified from octa- and penta-BDE mixtures and revealed, for the first time, a comprehensive microbial PBDE debromination pathway. As an acetogenic autotroph that rapidly debrominates octa- and penta-BDE technical mixtures, Acetobacterium sp. strain AG adds to the still-limited understanding of PBDE debromination by microorganisms. PMID:23204415

Ding, Chang; Chow, Wai Ling

2013-01-01

399

Mixtures of chemical pollutants at European legislation safety concentrations: how safe are they?  

PubMed

The risk posed by complex chemical mixtures in the environment to wildlife and humans is increasingly debated, but has been rarely tested under environmentally relevant scenarios. To address this issue, two mixtures of 14 or 19 substances of concern (pesticides, pharmaceuticals, heavy metals, polyaromatic hydrocarbons, a surfactant, and a plasticizer), each present at its safety limit concentration imposed by the European legislation, were prepared and tested for their toxic effects. The effects of the mixtures were assessed in 35 bioassays, based on 11 organisms representing different trophic levels. A consortium of 16 laboratories was involved in performing the bioassays. The mixtures elicited quantifiable toxic effects on some of the test systems employed, including i) changes in marine microbial composition, ii) microalgae toxicity, iii) immobilization in the crustacean Daphnia magna, iv) fish embryo toxicity, v) impaired frog embryo development, and vi) increased expression on oxidative stress-linked reporter genes. Estrogenic activity close to regulatory safety limit concentrations was uncovered by receptor-binding assays. The results highlight the need of precautionary actions on the assessment of chemical mixtures even in cases where individual toxicants are present at seemingly harmless concentrations. PMID:24958932

Carvalho, Raquel N; Arukwe, Augustine; Ait-Aissa, Selim; Bado-Nilles, Anne; Balzamo, Stefania; Baun, Anders; Belkin, Shimshon; Blaha, Ludek; Brion, François; Conti, Daniela; Creusot, Nicolas; Essig, Yona; Ferrero, Valentina E V; Flander-Putrle, Vesna; Fürhacker, Maria; Grillari-Voglauer, Regina; Hogstrand, Christer; Jonáš, Adam; Kharlyngdoh, Joubert B; Loos, Robert; Lundebye, Anne-Katrine; Modig, Carina; Olsson, Per-Erik; Pillai, Smitha; Polak, Natasa; Potalivo, Monica; Sanchez, Wilfried; Schifferli, Andrea; Schirmer, Kristin; Sforzini, Susanna; Stürzenbaum, Stephen R; Søfteland, Liv; Turk, Valentina; Viarengo, Aldo; Werner, Inge; Yagur-Kroll, Sharon; Zounková, Radka; Lettieri, Teresa

2014-09-01

400

Laminar Flame Speeds of Moist Syngas Mixtures  

SciTech Connect

This work experimentally investigates the effect of the presence of water vapor on the laminar flame speeds of moist syngas/air mixtures using the counterflow twin-flame configuration. The experimental results presented here are for fuel lean syngas mixtures with molar percentage of hydrogen in the hydrogen and carbon monoxide mixture varying from 5% to 100%, for an unburned mixture temperature of 323 K, and under atmospheric pressure. At a given equivalence ratio, the effect of varying amount of water vapor addition on the measured laminar flame speed is demonstrated. The experimental laminar flame speeds are also compared with computed values using chemical kinetic mechanisms reported in the literature. It is found that laminar flame speed varies non-monotonically with addition of water for the carbon monoxide rich mixtures. It first increases with increasing amount of water addition, reaches a maximum value, and then decreases. An integrated reaction path analysis is further conducted to understand the controlling mechanism responsible for the non-monotonic variation in laminar flame speed due to water addition. On the other hand, for higher values of H{sub 2}/CO ratio the laminar flame speed monotonically decreases with increasing water addition. It is shown that the competition between the chemical and thermal effects of water addition leads to the observed response. Furthermore, reaction rate sensitivity analysis as well as binary diffusion coefficient sensitivity analysis are conducted to identify the possible sources of discrepancy between the experimental and predicted values. The sensitivity results indicate that the reaction rate constant of H{sub 2} + OH = H{sub 2}O + H is worth revisiting and refinement of binary diffusion coefficient data of N{sub 2}–H{sub 2}O, N{sub 2}–H{sub 2}, and H{sub 2}–H{sub 2}O pairs can be considered.

Das, A. K.; Kumar, K.; Zhang, Z.; Sung, C. J.

2011-01-01

401

Ecotoxicity of paint mixtures: comparison between measured and calculated toxicity.  

PubMed

The aims of the current study were to test the validity of the concentration addition (CA) and independent action (IA) calculation methods for mixture toxicity as well as the REACH guidelines for mixture exposure scenarios for paint products. Based on ecotoxicity tests of nine anticorrosive paint mixtures and the nine substances that contributed to classification of the mixtures as hazardous for the aquatic environment, neither CA nor IA was found to be appropriate calculation methods, although CA calculations were conservative for half of the mixtures tested. The REACH mixture approach, based on "lead" substances, resulted in conservative predictions for three out of five mixtures and the "lead" substance corresponded to the substance contributing the most in the CA mixture calculations for four out of six mixtures. The use of paints as a matrix for toxicity testing required adaptation of test procedures, development of sample handling and chemical analysis methods. PMID:22892347

Gade, Anne Lill; Heiaas, Harald; Lillicrap, Adam; Hylland, Ketil

2012-10-01

402

Synergetic Antimicrobial Effects of Mixtures of Ethiopian Honeys and Ginger Powder Extracts on Standard and Resistant Clinical Bacteria Isolates  

PubMed Central

Purpose. To evaluate antimicrobial effects of mixtures of Ethiopian honeys and ginger rhizome powder extracts on Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922), Staphylococcus aureus (MRSA), Escherichia coli (R), and Klebsiella pneumoniae (R). Methods. Agar diffusion and broth assays were performed to determine susceptibility of these standard and resistant clinical bacteria isolates using honey-ginger powder extract mixtures. Results. Honey-ginger powder extract mixtures produced the highest mean inhibition (25.62?mm ± 2.55) compared to the use of honeys (21.63?mm ± 3.30) or ginger extracts (19.23?mm ± 3.42) individually. The ranges of inhibitions produced by honey-ginger extract mixtures on susceptible test organisms (26–30?mm) and resistant strains (range: 19–27?mm) were higher compared to 7–22?mm and 0–14?mm by standard antibiotic discs. Minimum inhibitory concentrations (MIC) of mixture of honeys-ginger extracts were 6.25% (0.625?v/mL) on the susceptible bacteria compared to 75% for resistant clinical isolates. Minimum bactericidal concentration (MBC) of honey-ginger extracts was 12.5% (0.125?g/mL) for all the test organisms. Conclusion. The result of this study showed that honey-ginger powder extract mixtures have the potential to serve as cheap source of antibacterial agents especially for the drug resistant bacteria strains. PMID:24772182

Ewnetu, Yalemwork; Lemma, Wossenseged; Birhane, Nega

2014-01-01

403

METHOD FOR TESTING THE AQUATIC TOXICITY OF SEDIMENT EXTRACTS FOR USE IN IDENTIFYING ORGANIC TOXICANTS IN SEDIMENTS  

EPA Science Inventory

Biologically-directed fractionation techniques are a fundamental tool for identifying the cause of toxicity in environmental samples, but few are available for studying mixtures of organic chemicals in aquatic sediments. This paper describes a method for extracting organic chemic...

404

Unusual solvatochromic absorbance probe behaviour within mixtures of poly(ethylene glycol)-400+ionic liquid, [bmim][Tf2N].  

PubMed

The potentially green solvents made up of ionic liquids (ILs) and poly(ethylene glycols) may have wide range of the applications in many chemical and biochemical fields. In the present work, solvatochromic absorbance probe behaviour is used to assess the physicochemical properties of the mixtures composed of PEG-400+IL, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [bmim][Tf2N]. Lowest energy intramolecular charge-transfer absorbance maxima of a betaine dye, i.e., E(T)(N), indicates the dipolarity/polarizability and/or hydrogen-bond donating (HBD) acidity of the [bmim][Tf2N]+PEG-400 mixtures to be even higher than that of neat [bmim][Tf2N], the solution component with higher dipolarity/polarizability and/or HBD acidity. Dipolarity/polarizability (?(?)) obtained separately from the electronic absorbance response of probe N,N-diethyl-4-nitroaniline, and the HBD acidity (?) of PEG-400+[bmim][Tf2N] mixtures are also observed to be anomalously high. A comparative study of the PEG+IL mixtures has also been done with PEG-400+molecular organic solvents (protic polar [methanol], aprotic polar [N,N-dimethylformamide], and non polar, [benzene]) mixtures, but these mixtures do not show this type of unusual behaviour. A four-parameter simplified combined nearly ideal binary solvent/Redlich-Kister (CNIBS/R-K) equation is shown to satisfactorily predict the solvatochromic parameters within PEG-400+different solvent mixtures. PMID:24280298

Ali, Anwar; Ali, Maroof; Malik, Nisar Ahmad; Uzair, Sahar

2014-01-01

405

Laboratory evaluation of crumb rubber asphalt concrete mixtures using the concepts of SMA mixtures  

E-print Network

the potential to significantly improve the resistance to fatigue and thermal cracking characteristics of asphalt concrete mixtures. The wet method appears to yield better performance regardless of the rubber particle size. Fine rubber would improve the fatigue...

Rebala, Somasekhar Reddy

1994-01-01

406

Environmental Organizations  

NSDL National Science Digital Library

This online reference list provides links to nine local and national environmental organizations that have Web sites rich in valuable biodiversity information. Where possible, it includes the following information for each: details about the organization's mission, knowledge base, and activities; the type of support offered, including educational materials, resource libraries, and classes/workshops; and mailing address and contact information. In addition, links to four Web directories are provided, which in turn have links to dozens of other organizations.

407

Multiple-technique analytical characterization of a mixture containing chemical-weapons simulant from a munition  

Microsoft Academic Search

An amber yellow organic liquid was found in a munition shell at Dugway Proving Grounds, UT, USA, that was likely used as a simulant of chemical weapons. The primary analytical techniques to characterize the mixture were gas chromatography–infrared detection–mass spectral detection (GC–IR–MS); liquid chromatography–mass spectrometry (LC–MS); nuclear magnetic resonance (NMR) using the nuclei 1H, 13C and 31P; and gas chromatography–atomic

William R Creasy; Barry R Williams; Kevin M Morrissey; Richard J O’Connor; H Dupont Durst

2000-01-01

408

Synthesis of maleic and pHthalic anhydrides from the mixture of cyclopentene and 1-pentene  

Microsoft Academic Search

The selective oxidations of cyclopentene, 1-pentene, and their mixture to maleic and phthalic anhydrides have been studied\\u000a to gain information on the total utilization of olefins of C5-fraction. The highest selectivities for maleic anhydride, a single major organic product, in individual oxidations of cyclopentene\\u000a and 1-pentene were obtained at complete or almost complete conversion, and then the main byproduct was

Young Ho Kim; Hyun Soo Yang

2000-01-01

409

Computational Study of the Self-Organization of Bidisperse Nanoparticles  

E-print Network

Computational Study of the Self-Organization of Bidisperse Nanoparticles Brooks D. Rabideau. In Final Form: July 14, 2004 We study computationally the self-organization of bidisperse mixtures of thiol these days. Self-assembly or "bottom up" methods of manufacture are being explored as an alternative means

410

CHEMICAL TRANSPORT FACILITATED BY COLLOIDAL-SIZED ORGANIC MOLECULES  

EPA Science Inventory

The fluid passing through the pores of soils and geologic materials is not just water with dissolved inorganic chemicals, but a complex mixture of organic and inorganic molecules. Large organic molecules such as humic and fulvic materials may impact the movement of contaminants. ...

411

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

PubMed

This study characterized the carbon and phosphorus composition of buffalo manure, its compost and vermicompost and investigated if presence of bamboo biochar has an effect on their chemical and biological reactivity. The four substrates were characterized for chemical and biochemical composition and P forms. The biological stability of the four substrates and their mixtures were determined during an incubation experiment. Their chemical reactivity was analyzed after acid dichromate oxidation. Biological reactivity of these substrates was related to their soluble organic matter content, which decreased in the order buffalo manure>compost>vermicompost. Phosphorus was labile in all organic substrates and composting transformed organic P into plant available P. The presence of biochar led to a protection of organic matter against chemical oxidation and changed their susceptibility to biological degradation, suggesting that biochar could increase the carbon sequestration potential of compost, vermicompost and manure, when applied in mixture. PMID:24071441

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

2013-11-01

412

High-speed mixture fraction imaging  

NASA Astrophysics Data System (ADS)

Advances in high-speed laser and camera technology have made scientific kHz repetition rate combustion and flow laser diagnostics feasible. While quantitative flow-field results have been shown to be possible via PIV, measuring scalars relevant to combustion such as mixture fraction, temperature and species concentrations is still a significant challenge. Tracer-LIF has proven to be a useful tool for imaging of mixture fraction. This paper highlights recent success at extending this technique for use at 9.5 kHz acquisition rate. The measurements are taken near the exit of an isothermal round jet seeded with acetone. Results taken at both maximum possible signal and a practical configuration for reacting flows are contrasted. Data are fully quantified and corrected for not only absorption, optical uniformity and laser pulse variation, but also for individual CMOS pixel offset and sensitivity.

Gordon, R. L.; Heeger, C.; Dreizler, A.

2009-09-01

413

Heavy-light fermion mixtures at unitarity  

SciTech Connect

We investigate fermion pairing in the unitary regime for a mass ratio corresponding to a {sup 6}Li-{sup 40}K mixture using quantum Monte Carlo methods. The ground-state energy and the average light- and heavy-particle excitation spectrum for the unpolarized superfluid state are nearly independent of the mass ratio. In the majority light system, the polarized superfluid is close to the energy of a phase separated mixture of nearly fully polarized normal and unpolarized superfluid. For a majority of heavy particles, we find an energy minimum for a normal state with a ratio of {approx}3:1 heavy to light particles. A slight increase in attraction to k{sub F}a{approx}2.5 yields a ground state energy of nearly zero for this ratio. A cold unpolarized system in a harmonic trap at unitarity should phase separate into three regions, with a shell of unpolarized superfluid in the middle.

Gezerlis, Alexandros [Los Alamos National Laboratory; Carlson, Joseph [Los Alamos National Laboratory; Gandol, S [UNIV. ILL; Schmidt, E [ITALY

2009-01-01

414

Heavy-Light Fermion Mixtures at Unitarity  

E-print Network

We investigate fermion pairing in the unitary regime for a mass ratio corresponding to a 6Li-40K mixture using Quantum Monte Carlo methods. The ground-state energy and the average light and heavy particle excitation spectrum for the unpolarized superfluid state are nearly independent of the mass ratio. In the majority light system, the polarized superfluid is close to the energy of a phase separated mixture of nearly fully polarized normal and unpolarized superfluid. For a majority of heavy particles, we find an energy minimum for a normal state with a ratio of ~ 3:1 heavy to light particles. A slight increase in attraction to kF*a ~ 2.5 yields a ground state energy of nearly zero for this ratio. A cold unpolarized system in a harmonic trap at unitarity should phase separate into three regions, with a shell of unpolarized superfluid in the middle.

Alexandros Gezerlis; S. Gandolfi; K. E. Schmidt; J. Carlson

2009-01-20

415

NMRI Measurements of Flow of Granular Mixtures  

NASA Technical Reports Server (NTRS)

We investigate complex 3D behavior of granular mixtures in shaking and shearing devices. NMRI can non-invasively measure concentration, velocity, and velocity fluctuations of flows of suitable particles. We investigate origins of wall-shear induced convection flow of single component particles by measuring the flow and fluctuating motion of particles near rough boundaries. We also investigate if a mixture of different size particles segregate into their own species under the influence of external shaking and shearing disturbances. These non-invasive measurements will reveal true nature of convecting flow properties and wall disturbance. For experiments in a reduced gravity environment, we will design a light weight NMR imager. The proof of principle development will prepare for the construction of a complete spaceborne system to perform experiments in space.

Nakagawa, Masami; Waggoner, R. Allen; Fukushima, Eiichi

1996-01-01

416

Embedded Electronic Nose for VOC Mixture Analysis  

SciTech Connect

This paper details the work done towards a low cost, small size, portable embedded electronic nose (e-nose) and its application for analysis of different VOC mixtures. The sensor array is composed of commercially available metal oxide semiconductor sensors by Figaro. The embedded E-nose consists of an ADuC831 and has an RS 232 interface for Desktop PC for higher level data collection and NN training. The ESP tool with database facility and multilayer perceptron neural network (MLP NN) is employed to interface the embedded hardware and to process the electronic nose signals before being classified. The use of embedded e-nose for the quantification of VOCs in mixtures is investigated.

Botre, B.; Gharpure, D.; Shaligram, A. [Department of Electronic Science, University of Pune, Pune: 411007 (India)

2009-05-23

417

Dusty Plasma Structures in Gas Mixtures  

SciTech Connect

The possibility of attainment of large Mach numbers is analyzed for the case of heavy ions drifting in a light gas. Under conditions of typical experiments with dust structures in plasmas, the use of the mixture of light and heavy gases is shown to make it possible to suppress the ion heating in the electric field and to form supersonic flows characterized by large Mach numbers. The drift of krypton ions in helium is considered as an example. Experiments with dc glow discharge at 1-10% of Kr show that the transition to the discharge in mixture leads to increase of interaction anisotropy and reinforcement of coupling of dust particles in the direction of ion drift. On the other hand, under certain conditions the phenomenon of abnormal 'heating' of dust particles was observed when the particles can obtain high kinetic energy which is several orders of magnitude higher than typical.

Popova, D. V.; Antipov, S. N.; Petrov, O. F.; Fortov, V. E. [Joint Institute for High Temperatures, Russian Academy of Sciences, Izhorskaya Str. 13/19, build 2, 125412 Moscow (Russian Federation); Maiorov, S. A. [A. M. Prokhorov General Physics Institute, Russian Academy of Sciences, Vavilov Str. 38, 119991 Moscow (Russian Federation)

2008-09-07

418

Mixture segregation by an inertial cavitation bubble.  

PubMed

Pressure diffusion is a mass diffusion process forced by pressure gradients. It has the ability to segregate two species of a mixture, driving the densest species toward high pressure zones, but requires very large pressure gradients to become noticeable. An inertial cavitation bubble develops large pressure gradients in its vicinity, especially as the bubble rebounds at the end of its collapse, and it is therefore expected that a liquid mixture surrounding such a bubble would become segregated. Theory developed in an earlier paper shows that this is indeed the case for sufficiently large molecules or nano-particles. The main theoretical results are recalled and a possible implication of this segregation phenomenon on the well-known cavitation-enhanced crystals nucleation is proposed. PMID:17208505

Grossier, R; Louisnard, O; Vargas, Y

2007-04-01

419

Comparison of species-rich cover crop mixtures in Hungarian vineyards  

NASA Astrophysics Data System (ADS)

In case of vine growing, agricultural practices of the past decades - as mechanical cultivation on steep vineyard slopes - can endanger the soil of vineyards. Moreover, climate change scenarios predict heavier rainstorms, which can also promote the degradation of the soil. These are some of the reasons why sustainable floor management plays an increasingly important role in viticulture recently. The use of cover crops in the inter-row has a special importance, especially on steep slopes and in case of organic farming to provide conditions for environmental friendly soil management. Species-rich cover crop seed mixtures may help to prevent erosion and create easier cultivation circumstances. Furthermore they have a positive effect on soil structure, soil fertility and ecosystem functions. However, it is important to find suitable seed mixtures for specific production sites, consisting ideally of native species from local provenance, adapted to the local climate/vine region/vineyard. Requirements for suitable cover crop species are as follows: they should save the soil from erosion and also from compaction caused by the movement of workers and machines, they should not compete significantly with the grapevines, or influence produce quality. We started to develop and apply several species-rich cover crop seed mixtures in spring 2012. During the experiments, three cover crop seed mixtures (Biocont-Ecovin mixture, mixture of legumes, mixture of grasses and herbs) were compared in vineyards of the Tokaj and Szekszárd vine regions of Hungary. Each mixture was sown in three consecutive inter-rows at each experimental site (all together 10 sites). Besides botanical measurements, yield, must quality, and pruning weight was studied in every treatment. The botanical survey showed that the following species of the mixtures established successfully and prospered during the years 2012 and 2013: Coronilla varia, Lotus corniculatus, Medicago lupulina, Onobrychis viciifolia, Plantago lanceolata, Trifolium pratense, Trifolium repens and Vicia sativa. We found that weed cover was lower in every treatment compared to the unsown control plots, thus, cover crops suppressed weeds of the inter-rows effectively. Most examined indices of grapevines were not significantly affected by the applied cover crop. However, the tendency of the results shows that in the drier climate of Hungary every second inter-row sowing is more preferable than consecutive cover-crop application, where erosion control is not essential. The opinion of the growers about the mixtures varied. The Biocont-Ecovin mixture was praised for its early aesthetic qualities, produced by Camelina sativa, Phacelia tanacetifolia and Sinapis alba. However, it was criticized for its non-native species, the foreign provenance of some seeds, and the height of the vegetation. The other two mixtures did not produce a spectacular flowering, but developed a lower canopy, and were praised for their native species content. Due to spring sowing the grass-herb mixture, containing a number of species with autumn germination, produced the lowest coverage among the tested mixtures in the first year. However, as predicted, it performed satisfactorily in the second year of the trial. The interest of the vine-growers underlines the importance of the topic for the Central-Eastern European region, thus further examination will be continued in 2014.

Donkó, Adam; Miglécz, Tamas; Valkó, Orsolya; Török, Peter; Deák, Balazs; Kelemen, Andras; Zanathy, Gabor; Drexler, Dora

2014-05-01

420

Leadership, Organizations  

E-print Network

Leadership, Policy & Organizations #12;2 At Peabody students have the opportunity to develop new College, in the Department of Leadership, Policy and Organizations (LPO). The faculty believes Patricia and Rodes Hart Chair, and Professor of Education Policy and Leadership, Ellen Goldring also serves

Palmeri, Thomas

421

Organ Systems  

NSDL National Science Digital Library

This "Organ Systems" module has five units of instruction that focus on the main classes of functions that a body must perform. Rather than just naming organs of the body and what they do, they present a perspective on the body as a coordinated group of systems that must do certain things correctly in order to survive and thrive.

Klemm, W. R.

2001-01-01

422

Model Organisms  

NSDL National Science Digital Library

A human is a complicated organism, and it is considered unethical to do many kinds of experiments on human subjects. For these reasons, biologists often use simpler âÃÂÃÂmodelâÃÂàorganisms that are easy to keep and manipulate in the laboratory. Despite ob

2009-04-14

423

Organizing Research.  

ERIC Educational Resources Information Center

Students are responsible for their own knowledge construction in student-centered, constructivist-learning environments. To be successful, students need tools, or organizers, to help explore relationships, organize information, and think critically. This article discusses and provides examples of presearch, search, interpretation, communication,…

Pappas, Marjorie L.

1997-01-01

424

Non-electrolyte viscous liquid mixtures  

E-print Network

rate theory approaches pioneered by Andrade, Frenkel, and Eyring. Examine viscosity rate equations beginning w1th Eyring (1937) to the present in order to focus on the strengths and weaknesses of the rate theory approach to correlating mixture vis...- cosities. Recent advances in statistical mechanical pro- cedures will be utilized in order to define categories of theoret1cal and empirical equations with respect to their functional dependence on chemical composition. Since neither statistical...

Wakefield, Dawn Lee

2012-06-07

425

Wire Counters with a New Gas Mixture  

Microsoft Academic Search

A multiwire chamber using a gas mixture of argon, isobutane and ¿-trichlorethane-1, 1, 1 (CH3.CCl3) has been successfully operated. Although this chamber does not operate in the proportional mode (i.e., pulse height is not a linear function of the primary ionization) we feel it has a substantial advantage over conventional proportional chambers especially when it is used to detect high

M. Atac

1972-01-01

426

Conformal Solution Theory: Hard-Sphere Mixtures  

Microsoft Academic Search

Conformal solution theory is examined. It is suggested that most difficulties associated with previous applications of this theory arise from the use of concentration-independent reference fluids. For the particular case of a hard-sphere mixture, it is shown that if the reference fluid is chosen so as to make the first-order term in the theory vanish, good results are obtained.

Douglas Henderson; Peter J. Leonard

1971-01-01

427

Population mixture model for nonlinear telomere dynamics  

NASA Astrophysics Data System (ADS)

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

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

2008-12-01

428

Toxic responses of bivalves to metal mixtures  

SciTech Connect

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

Mathew, P.; Menon, N.R. (Cochin Univ. of Science and Technology (India))

1992-02-01

429

Shear viscosity of hadronic gas mixtures  

E-print Network

We investigate the effects of baryon chemical potential \\mu on the shear viscosity coefficient \\eta and the viscosity to entropy density ratio \\eta/s of a pion-nucleon gas mixture. We find that \\eta is an increasing function of T and \\mu, while the ratio \\eta/s turns to a decreasing function in a wide region of T-\\mu plane. In the kinematical region we studied, the smallest value of \\eta/s is about 0.3.

K. Itakura; O. Morimatsu; H. Otomo

2008-05-12

430

Free wave propagation in binary gas mixtures  

Microsoft Academic Search

The problem concerning the propagation of free waves in binary mixtures of monatomic ideal gases is analyzed by using a kinetic model of the Boltzmann equation which is compatible with the two-fluid hydrodynamic theory. Comparison of the theoretical results with available experimental data shows that the two-fluid model equation can be used to describe the wave-vector dependence of the free

A. S. Fernandes; W. Marques Jr

2005-01-01

431

Thermal conductivities of ternary liquid mixtures  

SciTech Connect

A new, transient, hot-wire thermal conductivity cell has been constructed, calibrated against pure liquid toluene, and used to measure mixture thermal conductivity values in six ternary systems at 298 K and ambient pressure. These data have been used to test the accuracy of commonly used models/correlations that are both predictive in nature and extendable to multicomponent systems. For these six systems, the order of model accuracy was power law, local composition, LI, and ideal equations.

Rowley, R.L.; White, G.L.

1987-01-01

432

Dynamic thermodiffusion model for binary liquid mixtures  

NASA Astrophysics Data System (ADS)

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

Eslamian, Morteza; Saghir, M. Ziad

2009-07-01

433

Chemical Mixture Risk Assessment Additivity-Based Approaches  

EPA Science Inventory

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

434

BIOASSAY OF COMPLEX MIXTURES OF INDOOR AIR POLLUTANTS  

EPA Science Inventory

Indoor air pollution is a complex mixture of chemicals originating from outdoor air and indoor sources. oxicology studies of these mixtures are limited by difficulties in obtaining indoor air samples or appropriately simulated exposures. he concentration of pollutants from indoor...

435

A Simple Mixture Theory for ? Newtonian and Generalized Newtonian Constituents  

E-print Network

This work presents development of mathematical models based on conservation laws for a saturated mixture of ? homogeneous, isotropic, and incompressible constituents for isothermal flows. The constituents and the mixture ...

Powell, Michael Joseph

2012-08-31

436

RESULTS OF IPCS COLLABORATIVE STUDY ON COMPLEX MIXTURES  

EPA Science Inventory

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

437

40 CFR 160.113 - Mixtures of substances with carriers.  

Code of Federal Regulations, 2011 CFR

...test, control, or reference substance in the mixture. (2) When relevant to the conduct of the study, to determine the solubility of each test, control, or reference substance in the mixture by the testing facility or the sponsor before the...

2011-07-01

438

40 CFR 160.113 - Mixtures of substances with carriers.  

Code of Federal Regulations, 2012 CFR

...test, control, or reference substance in the mixture. (2) When relevant to the conduct of the study, to determine the solubility of each test, control, or reference substance in the mixture by the testing facility or the sponsor before the...

2012-07-01

439

40 CFR 160.113 - Mixtures of substances with carriers.  

Code of Federal Regulations, 2010 CFR

...test, control, or reference substance in the mixture. (2) When relevant to the conduct of the study, to determine the solubility of each test, control, or reference substance in the mixture by the testing facility or the sponsor before the...

2010-07-01

440

40 CFR 792.113 - Mixtures of substances with carriers.  

Code of Federal Regulations, 2013 CFR

...control, or reference substance in the mixture. (2) When relevant to the conduct of the experiment, to determine the solubility of each test, control, or reference substance in the mixture by the testing facility or the sponsor before the...

2013-07-01

441

40 CFR 792.113 - Mixtures of substances with carriers.  

Code of Federal Regulations, 2014 CFR

...control, or reference substance in the mixture. (2) When relevant to the conduct of the experiment, to determine the solubility of each test, control, or reference substance in the mixture by the testing facility or the sponsor before the...

2014-07-01

442

40 CFR 792.113 - Mixtures of substances with carriers.  

Code of Federal Regulations, 2012 CFR

...control, or reference substance in the mixture. (2) When relevant to the conduct of the experiment, to determine the solubility of each test, control, or reference substance in the mixture by the testing facility or the sponsor before the...

2012-07-01

443

40 CFR 792.113 - Mixtures of substances with carriers.  

Code of Federal Regulations, 2010 CFR

...control, or reference substance in the mixture. (2) When relevant to the conduct of the experiment, to determine the solubility of each test, control, or reference substance in the mixture by the testing facility or the sponsor before the...

2010-07-01

444

40 CFR 160.113 - Mixtures of substances with carriers.  

Code of Federal Regulations, 2014 CFR

...test, control, or reference substance in the mixture. (2) When relevant to the conduct of the study, to determine the solubility of each test, control, or reference substance in the mixture by the testing facility or the sponsor before the...

2014-07-01

445

40 CFR 160.113 - Mixtures of substances with carriers.  

Code of Federal Regulations, 2013 CFR

...test, control, or reference substance in the mixture. (2) When relevant to the conduct of the study, to determine the solubility of each test, control, or reference substance in the mixture by the testing facility or the sponsor before the...

2013-07-01

446

MIXTURES OF FINE-GRAINED MINERALS KAOLINITE AND CARBONATE GRAINS  

E-print Network

; Carman, 1937; White and Walton, 1937; German, 1989), while mixtures of rounded sand and platy mica grains without mica (Guimaraes, 2002). Mixtures of fine and coarse grains exhibit unique behavior, often related

Palomino, Angelica M.

447

21 CFR 1310.13 - Exemption of chemical mixtures; application.  

Code of Federal Regulations, 2010 CFR

... 2010-04-01 false Exemption of chemical mixtures; application. 1310.13...JUSTICE RECORDS AND REPORTS OF LISTED CHEMICALS AND CERTAIN MACHINES § 1310.13 Exemption of chemical mixtures; application. (a)...

2010-04-01

448

Estimation of generalized mixtures and its application in image segmentation  

Microsoft Academic Search

We introduce in this work the notion of a generalized mixture and propose some methods for estimating it, along with applications to unsupervised statistical image segmentation. A distribution mixture is said to be \\

Yves Delignon; Abdelwaheb Marzouki; Wojciech Pieczynski

1997-01-01

449

A stochastic approximation algorithm for estimating mixture proportions  

NASA Technical Reports Server (NTRS)

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

Sparra, J.

1976-01-01

450

REFLEAK: NIST Leak/Recharge Simulation Program for Refrigerant Mixtures  

National Institute of Standards and Technology Data Gateway

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

451

Phase behaviour of very asymmetric binary mixtures  

NASA Astrophysics Data System (ADS)

The phase behaviour of very asymmetric binary mixtures can be understood in terms of the depletion interaction. For hard particles this yields a narrow deep attractive well surrounding the hard core. Colloids with similar interaction potentials are known to destabilize the liquid, causing it to show a wide fluid-solid coexistence, and in extreme cases they exhibit an exotic solid-solid condensation. For a mixture this means that phase separation is not fluid-fluid, as previously thought, but normally fluid-solid, and if the asymmetry is very large, even solid-solid. We present in this work the result of devising a density functional theory for an infinitely asymmetric mixture of parallel hard cubes. This model is singular and undergoes a collapse in a close-packed solid (an extreme fluid-solid demixing). We avoid this collapse by introducing a small amount of polydispersity in the large particles; the resulting phase diagram shows the fluid-solid and solid-solid demixing scenarios described above.

Cuesta, José A.; Martínez-Ratón, Yuri

2000-02-01

452

Penalized maximum likelihood for multivariate Gaussian mixture  

NASA Astrophysics Data System (ADS)

In this paper, we first consider the parameter estimation of a multivariate random process distribution using multivariate Gaussian mixture law. The labels of the mixture are allowed to have a general probability law which gives the possibility to modelize a temporal structure of the process under study. We generalize the case of univariate Gaussian mixture in [1] to show that the likelihood is unbounded and goes to infinity when one of the covariance matrices approaches the boundary of singularity of the non negative definite matrices set. We characterize the parameter set of these singularities. As a solution to this degeneracy problem, we show that the penalization of the likelihood by an Inverse Wishart prior on covariance matrices results to a penalized or maximum a posteriori criterion which is bounded. Then, the existence of positive definite matrices optimizing this criterion can be guaranteed. We also show that with a modified EM procedure or with a Bayesian sampling scheme, we can constrain covariance matrices to belong to a particular subclass of covariance matrices. Finally, we study degeneracies in the source separation problem where the characterization of parameter singularity set is more complex. We show, however, that Inverse Wishart prior on covariance matrices eliminates the degeneracies in this case too.

Snoussi, Hichem; Mohammad-Djafari, Ali

2002-05-01

453

Dynamics of fluid mixtures in nanospaces.  

PubMed

A multicomponent extension of our recent theory of simple fluids [U. M. B. Marconi and S. Melchionna, J. Chem. Phys. 131, 014105 (2009)] is proposed to describe miscible and immiscible liquid mixtures under inhomogeneous, nonsteady conditions typical of confined fluid flows. We first derive from a microscopic level the evolution equations of the phase space distribution function of each component in terms of a set of self-consistent fields, representing both body forces and viscous forces (forces dependent on the density distributions in the fluid and on the velocity distributions). Second, we numerically solve the resulting governing equations by means of the lattice Boltzmann method, whose implementation contains novel features with respect to existing approaches. Our model incorporates hydrodynamic flow, diffusion, surface tension, and the possibility for global and local viscosity variations. We validate our model by studying the bulk viscosity dependence of the mixture on concentration, packing fraction, and size ratio. Finally, we consider inhomogeneous systems and study the dynamics of mixtures in slits of molecular thickness and relate structural and flow properties. PMID:21322672

Marconi, Umberto Marini Bettolo; Melchionna, Simone

2011-02-14

454

Tandem mass spectrometry: analysis of complex mixtures  

SciTech Connect

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

Singleton, K.E.

1985-01-01

455

Computational aspects of N-mixture models.  

PubMed

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

Dennis, Emily B; Morgan, Byron J T; Ridout, Martin S

2014-10-14

456

Dual-water mixture fuel burner  

DOEpatents

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

Brown, Thomas D. (Finleyville, PA); Reehl, Douglas P. (Pittsburgh, PA); Walbert, Gary F. (Library, PA)

1986-08-05

457

Negative Binomial Process Count and Mixture Modeling.  

PubMed

The seemingly disjoint problems of count and mixture modeling are united under the negative binomial (NB) process. A gamma process is employed to model the rate measure of a Poisson process, whose normalization provides a random probability measure for mixture modeling and whose marginalization leads to a NB process for count modeling. A draw from the NB process consists of a Poisson distributed finite number of distinct atoms, each of which is associated with a logarithmic distributed number of data samples. We reveal relationships between various count- and mixture-modeling distributions distributions, and construct a Poisson-logarithmic bivariate distribution that connects the NB and Chinese restaurant table distributions. Fundamental properties of the models are developed, and we derive efficient Bayesian inference. It is shown that with augmentation and normalization, the NB process and gamma-NB process can be reduced to the Dirichlet process and hierarchical Dirichlet process, respectively. These relationships highlight theoretical, structural and computational advantages of the NB process. A variety of NB processes, including the beta-geometric, beta-NB, marked-beta-NB, marked-gamma-NB and zero-inflated-NB processes, with distinct sharing mechanisms, are also constructed. These models are applied to topic modeling, with connections made to existing algorithms under Poisson factor analysis. Example results show the importance of inferring both the NB dispersion and probability parameters. PMID:24144977

Zhou, Mingyuan; Carin, Lawrence

2013-10-17

458

Synergy in Protein–Osmolyte Mixtures  

PubMed Central

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

2014-01-01

459

Efficient radiative transfer in dust grain mixtures  

E-print Network

The influence of a dust grain mixture consisting of spherical dust grains with different radii and/or chemical composition on the resulting temperature structure and spectral energy distribution of a circumstellar shell is investigated. The comparison with the results based on an approximation of dust grain parameters representing the mean optical properties of the corresponding dust grain mixture reveal that (1) the temperature dispersion of a real dust grain mixture decreases substantially with increasing optical depth, converging towards the temperature distribution resulting from the approximation of mean dust grain parameters, and (2) the resulting spectral energy distributions do not differ by more than 10% if >= 2^5 grain sizes are considered which justifies the mean parameter approximation and the many results obtained under its assumption so far. Nevertheless, the dust grain temperature dispersion at the inner boundary of a dust shell may amount to >>100K and has therefore to be considered in the correct simulation of, e.g., chemical networks. In order to study the additional influence of geometrical effects, a two-dimensional configuration -- the HH30 circumstellar disk -- was considered, using model parameters from Cotera et al. (2001) and Wood et al. (2002). A drastic inversion of the large to small grain temperature distribution was found within the inner approx. 1AU of the disk.

S. Wolf

2002-09-13

460

Addressing extrema and censoring in pollutant and exposure data using mixture of normal distributions  

PubMed Central

Background Volatile organic compounds (VOC), which include many hazardous chemicals, have been used extensively in personal, commercial and industrial products. Due to the variation in source emissions, differences in the settings and environmental conditions where exposures occur, and measurement issues, distributions of VOC concentrations can have multiple modes, heavy tails, and significant portions of data below the method detection limit (MDL). These issues challenge standard parametric distribution models needed to estimate the exposures, even after log-transformation of the data. Methods This paper considers mixture of distributions that can be directly applied to concentration and exposure data. Two types of mixture distributions are considered: the traditional finite mixture of normal distributions, and a semi-parametric Dirichlet process mixture (DPM) of normal distributions. Both methods are implemented for a sample data set obtained from the Relationship between Indoor, Outdoor and Personal Air (RIOPA) study. Performance is assessed based on goodness-of-fit criteria that compare the closeness of the density estimates with the empirical density based on data. The goodness-of-fit for the proposed density estimation methods are evaluated by a comprehensive simulation study. Results The finite mixture of normals and DPM of normals have superior performance when compared to the single normal distribution fitted to log-transformed exposure data. The advantages of using these mixture distributions are more pronounced when exposure data have heavy tails or a large fraction of data below the MDL. Distributions from the DPM provided slightly better fits than the finite mixture of normals. Additionally, the DPM method avoids certain convergence issues associated with the finite mixture of normals, and adaptively selects the number of components. Conclusions Compared to the finite mixture of normals, DPM of normals has advantages by characterizing uncertainty around the number of components, and by providing a formal assessment of uncertainty for all model parameters through the posterior distribution. The method adapts to a spectrum of departures from standard model assumptions and provides robust estimates of the exposure density even under censoring due to MDL. PMID:24348086

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

2013-01-01

461

Parental exposure to natural mixtures of POPs reduced embryo production and altered gene transcription in zebrafish embryos.  

PubMed

Determination of toxicity of complex mixtures has been proposed to be one of the most important challenges for modern toxicology. In this study we performed genome wide transcriptome profiling to assess potential toxicant induced changes in gene regulation in zebrafish embryos following parental exposure to two natural mixtures of persistent organic pollutants (POPs). The mixtures used were extracted from burbot (Lota lota) liver originating from two lakes (Lake Mjøsa and Lake Losna) belonging to the same freshwater system in Norway. The dominating groups of contaminants were polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane metabolites (DDTs). Because both mixtures used in the present study induced similar effects, it is likely that the same toxicants are involved. The Mjøsa mixture contains high levels of PBDEs while this group of pollutants is low in the Losna mixture. However, both mixtures contain substantial concentrations of PCB and DDT suggesting these contaminants as the predominant contributors to the toxicity observed. The observed effects included phenotypic traits, like embryo production and survival, and gene transcription changes corresponding with disease and biological functions such as cancer, reproductive system disease, cardiovascular disease, lipid and protein metabolism, small molecule biochemistry and cell cycle. The changes in gene transcription included genes regulated by HNF4A, insulin, LH, FSH and NF-?B which are known to be central regulators of endocrine signaling, metabolism, metabolic homeostasis, immune functions, cancer development and reproduction. The results suggest that relative low concentrations of the natural mixtures of POPs used in the present study might pose a threat to wild freshwater fish living in the lakes from which the POPs mixtures originated. PMID:23063069

Lyche, Jan L; Grze?, Irena M; Karlsson, Camilla; Nourizadeh-Lillabadi, Rasoul; Berg, Vidar; Kristoffersen, Anja B; Skåre, Janneche U; Alestrøm, Peter; Ropstad, Erik

2013-01-15

462

A new phonetic tied-mixture model for efficient decoding  

Microsoft Academic Search

A phonetic tied-mixture (PTM) model for efficient large vocabulary continuous speech recognition is presented. It is synthesized from context-independent phone models with 64 mixture components per state by assigning different mixture weights according to the shared states of triphones. Mixtures are then re-estimated for optimization. The model achieves a word error rate of 7.0% with a 20000-word dictation of newspaper

Akinobu Lee; Tatsuya Kawahara; Kazuya Takeda; Kiyohiro Shikano

2000-01-01

463

SORPTION OF 2,3,7,8-TETRACHLORODIBENZO-P-DIOXIN TO SOILS FROM WATER/METHANOL MIXTURES  

EPA Science Inventory

Sorption of 14C-labeled 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) to soils from water/methanol mixtures has been evaluated by batch shake testing. Uncontaminated soils from Times Beach, MO, were used in these experiments and ranged in fraction organic carbon (U...

464

SORPTION OF 2, 3, 7, 8-TETRACHLORODIBENZO-P-DIOXIN TO SOILS FROM WATER/METHANOL MIXTURES  

EPA Science Inventory

Sorption of 14 C-labeled 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCCD) to Soils from water/methanol mixtures has been evaluated by batch shake testing. ncontaminated soils from Times Beach, MO, were used in these experiments and ranged in fraction organic carbon (foc) from 0.0066 to...

465

Frontal polymerizations carried out in Deep-Eutectic mixtures providing both the monomers and the polymerization medium.  

PubMed

Deep Eutectic Solvents (DESs) based upon mixtures of Acrylic Acid (AA) or Methacrylic Acid (MAA) and Choline Chloride (CCl) demonstrated superior performance than regular organic solvents and even ionic liquids for frontal polymerizations (FPs). Full recovering of CCl after FP provided an interesting green character to the process. PMID:21455538

Mota-Morales, Josué D; Gutiérrez, María C; Sanchez, Isaac C; Luna-Bárcenas, Gabriel; del Monte, Francisco

2011-05-14

466

Environmentally Realistic Mixtures of the Five Regulated Haloacetic Acids Exhibit Concentration-Dependent Departures from Dose Additivity  

EPA Science Inventory

Disinfection of water decreases waterborne disease. Disinfection byproducts (DBPs) are formed by the reaction of oxidizing disinfectants with inorganic and organic materials in the source water. The U.S. EPA regulates five haloacetic acid (HAA) DBPs as a mixture. The objective ...

467

ORD'S FOUR LAB STUDY: TOXICOLOGICAL AND CHEMICAL EVALUATION OF COMPLEX MIXTURES OF DRINKING WATER DISINFECTION BY-PRODUCTS  

EPA Science Inventory

Disinfectants used in the production of drinking water react with naturally occurring organic and inorganic material in the source water to produce disinfection by-products (DBPs). Humans are exposed daily to a complex mixture of DBPs via oral, dermal, and inhalation routes. To ...

468