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Sample records for non-aqueous phase liquids

  1. Non-Aqueous Phase Liquid Calculator

    Energy Science and Technology Software Center (ESTSC)

    2004-02-19

    Non-Aqueous Phase Liquid or "NPAL" is a term that most environmental professionals are familiar with because NAPL has been recognized in the literature as a significant source of groundwater contamination. There are two types of NAPL: DNAPL and LNAPL. DNAPL is a ‘dense’ non-aqueous phase liquid. In this context, dense means having a density greater than water (1.0 kg/L). Trichloroethylene (TCE) and tetrachioroethylene (PCE) are examples of DNAPL compounds. A compound that is heaver thanmore » water means this type of NAPL will sink in an aquifer. Conversely, LNAPL is a ‘light’ non-aqueous phase liquid with a density less than water, and will float on top of the aquifer. Examples of LNAPL’s are benzene and toluene. LNAPL or DNAPL often manifest as a complex, multi-component mixture of organic compounds that can occur in environmental media. Complex multi-component mixtures distributed in soil pore-air, pore-water, soil particles and in free phase complicate residual saturation of single and multi component NAPL compounds in soil samples. The model output also includes estimates of the NAPL mass and volume and other physical and chemical properties that may be useful for characterization, modeling, and remedial system design and operation. The discovery of NAPL in the aquifer usually leads to a focused characterization for possible sources of NAPL in the vadose zone using a variety of innovative technologies and characterization methods. Often, the analytical data will indicated the presence of NAPL, yet, the NAPL will go unrecognized. Failure to recognize the NAPL can be attributed to the complicated processes of inter-media transfer or a general lack of knowledge about the physical characteristics of complex organic mixtures in environmental samples.« less

  2. Non-aqueous phase liquid spreading during soil vapor extraction

    NASA Astrophysics Data System (ADS)

    Kneafsey, Timothy J.; Hunt, James R.

    2004-02-01

    Many non-aqueous phase liquids (NAPLs) are expected to spread at the air-water interface, particularly under non-equilibrium conditions. In the vadose zone, this spreading should increase the surface area for mass transfer and the efficiency of volatile NAPL recovery by soil vapor extraction (SVE). Observations of spreading on water wet surfaces led to a conceptual model of oil spreading vertically above a NAPL pool in the vadose zone. Analysis of this model predicts that spreading can enhance the SVE contaminant recovery compared to conditions where the liquid does not spread. Experiments were conducted with spreading volatile oils hexane and heptane in wet porous media and capillary tubes, where spreading was observed at the scale of centimeters. Within porous medium columns up to a meter in height containing stagnant gas, spreading was less than ten centimeters and did not contribute significantly to hexane volatilization. Water film thinning and oil film pinning may have prevented significant oil film spreading, and thus did not enhance SVE at the scale of a meter. The experiments performed indicate that volatile oil spreading at the field scale is unlikely to contribute significantly to the efficiency of SVE.

  3. Method and device for removing a non-aqueous phase liquid from a groundwater system

    DOEpatents

    Looney, Brian B.; Rossabi, Joseph; Riha, Brian D.

    2002-01-01

    A device for removing a non-aqueous phase liquid from a groundwater system includes a generally cylindrical push-rod defining an internal recess therein. The push-rod includes first and second end portions and an external liquid collection surface. A liquid collection member is detachably connected to the push-rod at one of the first and second end portions thereof. The method of the present invention for removing a non-aqueous phase liquid from a contaminated groundwater system includes providing a lance including an external hydrophobic liquid collection surface, an internal recess, and a collection chamber at the bottom end thereof. The lance is extended into the groundwater system such that the top end thereof remains above the ground surface. The liquid is then allowed to collect on the liquid collection surface, and flow downwardly by gravity into the collection chamber to be pumped upwardly through the internal recess in the lance.

  4. Containment and recovery of a light non-aqueous phase liquid plume at a woodtreating facility

    SciTech Connect

    Crouse, D.; Powell, G.; Hawthorn, S.; Weinstock, S.

    1997-12-31

    A woodtreating site in Montana used a formulation (product) of 5 percent pentachlorophenol and 95 percent diesel fuel as a carrier liquid to pressure treat lumber. Through years of operations approximately 378,500 liters of this light non-aqueous phase liquid (LNAPL) product spilled onto the ground and soaked into the groundwater. A plume of this LNAPL product flowed in a northerly direction toward a stream located approximately 410 meters from the pressure treatment building. A 271-meter long high density polyethylene (HDPE) containment cutoff barrier wall was installed 15 meters from the stream to capture, contain, and prevent the product from migrating off site. This barrier was extended to a depth of 3.7 meters below ground surface and allowed the groundwater to flow beneath it. Ten product recovery wells, each with a dual-phase pumping system, were installed within the plume, and a groundwater model was completed to indicate how the plume would be contained by generating a cone of influence at each recovery well. The model indicated that the recovery wells and cutoff barrier wall would contain the plume and prevent further migration. To date, nearly 3{1/2} year`s later, approximately 106,000 liters of product have been recovered.

  5. Modeling metabolic reductive dechlorination in dense non-aqueous phase liquid source-zones

    NASA Astrophysics Data System (ADS)

    Christ, John A.; Abriola, Linda M.

    2007-06-01

    Recent laboratory experimental evidence has suggested that bioremediation may be an attractive management strategy for dense non-aqueous phase liquid (DNAPL) source-zones. In particular, metabolic reductive dechlorination has been shown to reduce aqueous phase chlorinated ethene contaminant concentrations and enhance DNAPL dissolution, reducing source longevity. Transitioning this technology from the laboratory to the field will be facilitated by tools capable of simulating bioenhanced dissolution. This work presents a mathematical model for metabolic reductive dechlorination in a macroscale two-phase (aqueous-organic) environment. The model is implemented through adaptation of an existing multi-phase compositional simulator, which has been modified to incorporate eight chemical components and four microbial populations: a fermentative population, two dechlorinating populations, and a competitor population (e.g., methanogens). Monod kinetics, modified to incorporate electron donor thresholds, electron acceptor competition, and competitor inhibition, are used to simulate microbial growth and component degradation. The developed model is numerically verified and demonstrated through comparisons with published column-scale dechlorination data. Dechlorination kinetics, electron donor concentrations, and DNAPL saturation and distribution are all found to affect the extent of dissolution enhancement, with enhancements ranging from 1.0 to ˜1.9. Comparison of simulation results with those from a simplified analytic modeling approach suggest that the analytical model may tend to over-predict dissolution enhancement and fail to account for the transient nature of dissolution enhancement, leading to significant (70%) under-prediction of source longevity.

  6. Push pull partitioning tracer tests using radon-222 to quantify non-aqueous phase liquid contamination

    NASA Astrophysics Data System (ADS)

    Davis, B. M.; Istok, J. D.; Semprini, L.

    2002-09-01

    Naturally occurring radon in groundwater can be used as an in situ partitioning tracer for locating and quantifying non-aqueous phase liquid (NAPL) contamination in the subsurface. When combined with the single-well, push-pull test, this methodology has the potential to provide a low-cost alternative to inter-well partitioning tracer tests. During a push-pull test, a known volume of test solution (radon-free water containing a conservative tracer) is first injected ("pushed") into a well; flow is then reversed and the test solution/groundwater mixture is extracted ("pulled") from the same well. In the presence of NAPL radon transport is retarded relative to the conservative tracer. Assuming linear equilibrium partitioning, retardation factors for radon can be used to estimate NAPL saturations. The utility of this methodology was evaluated in laboratory and field settings. Laboratory push-pull tests were conducted in both non-contaminated and trichloroethene NAPL (TCE)-contaminated sediment. The methodology was then applied in wells located in non-contaminated and light non-aqueous phase liquid (LNAPL)-contaminated portions of an aquifer at a former petroleum refinery. The method of temporal moments and an approximate analytical solution to the governing transport equations were used to interpret breakthrough curves and estimate radon retardation factors; estimated retardation factors were then used to calculate TCE saturations. Numerical simulations were used to further investigate the behavior of the breakthrough curves. The laboratory and field push-pull tests demonstrated that radon retardation does occur in the presence of TCE and LNAPL and that radon retardation can be used to calculate TCE saturations. Laboratory injection-phase test results in TCE-contaminated sediment yielded radon retardation factors ranging from 1.1 to 1.5, resulting in calculated TCE saturations ranging from 0.2 to 0.9%. Laboratory extraction-phase test results in the same sediment

  7. Infiltration characteristics of non-aqueous phase liquids in undisturbed loessal soil cores.

    PubMed

    Wang, Yunqiang; Shao, Ming'an

    2009-01-01

    The widespread contamination of soils and aquifers by non-aqueous phase liquids (NAPL), such as crude oil, poses serious environmental and health hazards globally. Understanding the infiltration characteristics of NAPL in soil is crucial in mitigating or remediating soil contamination. The infiltration characteristics of crude and diesel oils into undisturbed loessal soil cores, collected in polymethyl methacrylate cylindrical columns, were investigated under a constant fluid head (3 cm) of either crude oil or diesel oil. The infiltration rate of both crude and diesel oils decreased exponentially as wetting depth increased with time. Soil core size and bulk density both had significant effects on NAPL infiltration through the undisturbed soil cores; a smaller core size or a greater bulk density could reduce oil penetration to depth. Compacting soil in areas susceptible to oil spills may be an effective stratage to reduce contamination. The infiltration of NAPL into soil cores was spatially anisotropic and heterogeneous, thus recording the data at four points on the soil core is a good stratage to improve the accuracy of experimental results. Our results revealed that crude and diesel oils, rather than their components, have a practical value for remediation of contaminated loessal soils. PMID:19999998

  8. Recovery of light, non-aqueous phase liquid from porous media: laboratory experiments and model validation

    NASA Astrophysics Data System (ADS)

    Waddill, Dan W.; Parker, Jack C.

    1997-07-01

    Laboratory experiments were conducted to measure flow of a light, non-aqueous phase liquid (LNAPL or simply "oil") in porous media. The objective of these experiments was to measure oil recovery as influenced by hysteresis, the oil-water capillary fringe, and an oil seepage face. Oil was infiltrated and allowed to redistribute across the horizontal length of a two-dimensional tank filled with medium sand. The first experiment involved oil recovery without water pumping, while the second experiment involved oil recovery with water pumping to increase the gradient toward the recovery well. Observed oil recovery compared favorably with the predictions of a numerical model (ARMOS). A dual-energy gamma radiation attenuation system monitored oil and water saturations throughout the experiments, while hydrophobic tensiometers measured the location of the air-oil table (Z ao). The experimental distribution of oil saturations suggested the need to incorporate an oil-water capillary fringe in the calculation of oil trapping in the saturated zone. Measurements of Z ao indicated that hysteresis influenced the liquid saturation-pressure relationships. When the effects of hysteresis were incorporated into the model, predicted and measured values of Z ao came into agreement, especially at early times during the recovery process. Experimental data also suggested the presence of an oil seepage face at the pumping well, but model results were not sensitive to this factor. Oil saturation measurements at later times suggested that the oil may have experienced delayed yield, an effect that was not modeled explicitly. A sensitivity analysis revealed that oil recovery predictions were most affected by horizontal hydraulic conductivity, fluid scaling parameters βao and βow, and van Genuchten α, n, and Sm. Overall, the numerical model appeared to match measured data for oil saturation, pressure, and recovery under two sets of boundary conditions.

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

    SciTech Connect

    Rucker, G

    2006-09-22

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

  10. Test plan for Geo-Cleanse{reg_sign} demonstration (in situ destruction of dense non-aqueous phase liquid (DNAPL))

    SciTech Connect

    Jerome, K.M.; Looney, B.B.; Accorsi, F.; Dingens, M.; Wilson, J.T.

    1996-09-01

    Soils and groundwater beneath an abandoned process sewer line in the A/M Area of the Savannah River Site (SRS) contain elevated levels of volatile organic compounds, specifically trichloroethylene (TCE) and tetrachloroethylene (PCE), two common chlorinated solvents. These compounds have low aqueous solubilities, thus when released to the subsurface in sufficient quantity, tend to exist as immiscible fluids or nonaqueous phase liquids (NAPLs). Because chlorinated solvents are also denser than water, they are referred to by the acronym DNAPLs, or dense non-aqueous phase liquids. Technologies targeted at the efficient characterization or removal of DNAPL are not currently proven. For example, most DNAPL studies rely on traditional soil and water sampling and the fortuitous observation of immiscible solvent. Once DNAPL is identified, soil excavation (which is only applicable to small contained spill sites) is the only proven cleanup method. New cleanup approaches based on destruction of DNAPL either in situ or ex situ have been proposed and tested at the pilot scale. The proposed demonstration, as described in this report will evaluate the applicability to DNAPL plumes of a technology proven for in situ destruction of light non-aqueous phase liquids (LNAPLs) such as oils.

  11. Removal of non aqueous phase liquid liquid (NAPL) from a loam soil monitored by time domain reflectometry (TDR) technique

    NASA Astrophysics Data System (ADS)

    comegna, alessandro; coppola, Antonio; dragonetti, giovanna; ajeel, ali; saeed, ali; sommella, angelo

    2016-04-01

    Non-aqueous phase liquids (NAPLs) are compounds with low or no solubility with water. These compounds, due to the several human activities, can be accidentally introduced in the soil system and thus constitute a serious geo-environmental problem, given the toxicity level and the high mobility. The remediation of contaminated soil sites requires knowledge of the contaminant distribution in the soil profile and groundwater. Methods commonly used to characterize contaminated sites are coring, soil sampling and the installation of monitoring wells for the collection of groundwater samples. The main objective of the present research is to explore the potential application of time domain reflectometry (TDR) technique in order to evaluate the effect of contaminant removal in a loam soil, initially contaminated with NAPL and then flushed with different washing solutions. The experimental setup consist of: i) a Techtronix cable tester; ii) a three-wire TDR probe with wave guides 14.5 cm long inserted vertically into the soil samples; iii) a testing cell of 8 cm in diameter and 15 cm high; iv) a peristaltic pump for upward injection of washing solution. In laboratory, soil samples were oven dried at 105°C and passed through a 2 mm sieve. Known quantities of soil and NAPL (corn oil, a non-volatile and non-toxic organic compound) were mixed in order to obtain soil samples with different degrees of contamination. Once a soil sample was prepared, it was repacked into a plastic cylinder and then placed into the testing cell. An upward injection of washing solution was supplied to the contaminated sample with a rate q=1.5 cm3/min, which corresponds to a darcian velocity v=6.0 cm/h. The out coming fluid, from the soil column was collected, then the washing solution and oil was separated. Finally both the amount of oil that was remediated and the dielectric permittivity (measured via TDR) of the contaminated soil sample were recorded. Data collected were employed to implement a

  12. Cryogenic Coring and Magnetic Resonance Imaging for Quantification of Non-Aqueous Phase Liquids in Unconsolidated Soils

    NASA Astrophysics Data System (ADS)

    Kiaalhosseini, S.; Sale, T. C.; Watson, A. T.; Kohn, B. D.; Johnson, R. L.; Blotevogel, J.

    2014-12-01

    A novel approach of combining cryogenic coring of sediments with magnetic resonance imaging (MRI) of frozen soil cores is reported. Cryogenic coring has the potential to preserve critical properties of soil cores including the distribution of pore fluids. MRI can provide information on the qualitative and quantitative spatial distribution of non-aqueous phase liquid (NAPL) contaminants within the cores. Initial results of field-scale cryogenic coring indicated that injecting liquid nitrogen through a cooling coil around a soil core (6.3 cm diameter and 75 cm long) could freeze the core below the water table (water table at 7.2 m) in less than 15 minutes. MRI scanning of soil cores contaminated with trichloroethene (TCE) NAPL indicated that keeping the cores frozen at -20°C can suppress the competing MRI signals of water-bound hydrogen. Comparison of known and measured TCE NAPL saturation using MRI in spiked frozen soil samples showed close agreement. The results confirm the ability of cryogenic coring to prevent redistribution of pore fluids during sample withdrawal and storage. The results of MRI illustrate the ability of this method to discriminate between water and TCE in frozen cores, thus allowing for a sensitive spatial analysis of contaminant distribution. Overall, this novel combined approach has the potential to lower the cost of site investigation while providing an improved basis for site characterization and management.

  13. Detection of non-aqueous phase liquid contamination by SH-TE seismoelectrics: A computational feasibility study

    NASA Astrophysics Data System (ADS)

    Munch, Federico D.; Zyserman, Fabio I.

    2016-07-01

    In this work we propose a one dimensional numerical study of the seismoelectric signals produced in a fresh water aquifer contaminated by either light or dense non-aqueous phase liquids ((L/D)NAPLs), considering a pure SH-wave seismic source. We investigate the nature of the electromagnetic response generated at media interfaces, the so called Interface Response (IR), by comparing it with the electromagnetic field generated by a current sheet; wherefrom we are able to interpret that the source of the IR behaves as an electric current flowing along the interface, differently to what happens when the IR is originated by the action of a P-wave, where electric charge accumulation generates an electric dipole. We perform a parametric study to analyze how the presence of contaminants affects the IR, resorting to an effective media approach to compute mechanical and electromagnetic properties, and considering three different effective fluid-saturation dependent electrokinetic coupling coefficient models. We observe, as expected, that porosity plays an important role in the amplitude of the IRs. When considering different NAPL saturations, significant effects on the IRs are only seen when the thickness of the contaminated layer is above a threshold value, which depends on the present contaminant and the considered effective electrokinetic coupling coefficient model.

  14. Partitioning of non-ionic surfactants between water and non-aqueous phase liquids (NAPLs) of chlorinated organics

    NASA Astrophysics Data System (ADS)

    KANG, S.; Jeong, H. Y.

    2013-12-01

    Due to the hydrophobic nature, chlorinated organic compounds penetrate soil and groundwater to form non-aqueous phase liquids (NAPLs). At the sites contaminated with such NAPLs, thus, surfactants are applied to increase the aqueous solubility of chlorinated organics via micellar solubilization. However, a portion of surfactants can be partitioned into NAPL phases by forming reverse micelles within them. Consequently, lesser amounts of surfactants are available for the micellar solubilization of chlorinated organics in the aqueous phase. In this study, we investigated the partitioning behavior of non-ionic surfactants (Tween 20, Tween 40, Tween 80, and Triton X-100) between water and a NAPL phase consisting of tetrachloroethylene (PCE), trichloroethylene (TCE), or chloroform (CF). According to the experimental results, the partitioning of surfactants in the water-NAPL systems was found to follow linear or Langmuir-type isotherms. Regardless of type of surfactants, the partitioning loss of surfactants into NAPLs became greater with the more hydrophilic (i.e., the lower water-NAPL interfacial tension) chlorinated organics: PCE < TCE < CF. Notably, the partitioning of all Tween surfactants into the NAPLs consisting of the least hydrophilic PCE was minimal. The partitioning behavior among different surfactants was somewhat complicated. The partitioning extent into CF-NAPLs increased in the order of Tween 20 < Tween 40 < Tween 80 << Triton X-100, suggesting that the greater partitioning occurred with the more hydrophobic (i.e., the lower hydrophilic-lipophilic balance, HLB) surfactant. Consistent with this postulation, the surfactant partitioning into PCE-NAPLs showed the similar trend. In case of TCE-NAPLs, however, the more hydrophobic Tween 40 was partitioned to a less extent than Tween 20. Therefore, the specific interaction of a NAPL-surfactant pair as well as their individual properties should be considered when selecting an effective surfactant for the remediation

  15. Using radon as environmental tracer for the assessment of subsurface Non-Aqueous Phase Liquid (NAPL) contamination - A review

    NASA Astrophysics Data System (ADS)

    Schubert, M.

    2015-05-01

    The radioactive noble gas radon has an ambivalent nature: on the one hand is it of main concern with regard to radiation protection, on the other hand can it be applied as powerful tracer tool in various fields of applied geosciences. Due to its omnipresence in nature, its chemical and physical properties, and its uncomplicated detectability radon fulfils all requirements for being used as environmental tracer. This application is discussed in the paper with focus on the use of radon as tracer for subsurface contamination with Non-Aqueous Phase Liquids (NAPL). After a short introduction in the ambivalence and ubiquitous presence of radon in nature, the theoretical background of its suitability as NAPL tracer is summarized. Finally three potential applications are discussed. Background information and practical examples are given for (i) the investigation of residual NAPL contamination in soils, (ii) the investigation of residual NAPL contamination in aquifers and (iii) the monitoring of the remediation of dissolved NAPL contamination in groundwater. The presented information reveals that radon is an ideal tracer for the assessment of a wide range of subsurface NAPL contamination. Still, its application is not without restrictions. Problems may occur due to mineralogical heterogeneity of the soil or aquifer matrix. Furthermore, local changes in the permeability of the subsurface may be associated with preferential groundwater or soil gas flow paths bypassing isolated sub-domains of an investigated NAPL source zone. Moreover, NAPL aging may result in alterations in the composition of a complex NAPL mixture thus giving rise to significant changes of the radon partition coefficient between NAPL and water or soil gas. However, since radon shows a strong affinity to NAPLs in general, semi-quantitative results will always be possible.

  16. Effect of Humic Acid on Migration, Distribution and Remediation of Dense Non-aqueous Phase Liquids: A laboratory investigation

    NASA Astrophysics Data System (ADS)

    Cheng, Z.; Wu, J.; Xu, H.; Gao, Y.

    2014-12-01

    Over the last decades, dense non-aqueous phase liquids (DNAPLs) contamination in the subsurface increases with the rapid development of oil industry and becomes the focus of many studies. The migration, distribution and remediation efficiency of DNAPLs in the subsurface environment are greatly affected by the solution chemistry besides the physical heterogeneities of aquifers. Humic acid (HA), which is ubiquitous in natural environments, is a surface active substance exhibiting solubility enhancement behavior for hydrophobic organic compounds such as DNAPLs. Here we reported a laboratory investigation to study the effects of HA on the infiltration, immobilization and subsequent recovery of DNAPL in porous media. Tetrachloroethylene (PCE) was selected as the representative DNAPL in this study. Two-dimensional (2-D) sandbox experiments were conducted to investigate the effects of different HA concentrations on the transport, distribution of PCE and the remediation of PCE using surfactant (Tween 80) flushing in a saturated porous media system. The surfactant flushing of PCE was performed after the PCE transport and distribution had reached equilibrium. A light transmission visualization method with charge-coupled device (CCD) camera was adopted to visualize PCE distribution and quantify its saturation. In addition, the experiments were also designed to gather data for the validation of multiphase flow models. Effluent samples were collected to determine dissolved PCE concentrations. PCE solubilization and PCE-water interfacial tension were experimentally determined in aqueous solutions of varying HA concentrations. The experimental results showed that the presence of HA can have a dramatic impact on PCE flow and entrapment, and significantly improved the recovery of PCE during surfactant enhanced aquifer remediation (SEAR). The findings are of use for better understanding of the migration and entrapment of DNAPLs and developing of SEAR technology.

  17. Refinement of the Kansas City Plant site conceptual model with respect to dense non-aqueous phase liquids (DNAPL)

    SciTech Connect

    Korte, N.E.; Hall, S.C.; Baker, J.L.

    1995-10-01

    This document presents a refinement of the site conceptual model with respect to dense non-aqueous phase liquid (DNAPL) at the US Department of Energy Kansas City Plant (KCP). This refinement was prompted by a review of the literature and the results of a limited study that was conducted to evaluate whether pools of DNAPL were present in contaminated locations at the KCP. The field study relied on the micropurge method of sample collection. This method has been demonstrated as a successful approach for obtaining discrete samples within a limited aquifer zone. Samples were collected at five locations across 5-ft well screens located at the base of the alluvial aquifer at the KCP. The hypothesis was that if pools of DNAPL were present, the dissolved concentration would increase with depth. Four wells with highly contaminated groundwater were selected for the test. Three of the wells were located in areas where DNAPL was suspected, and one where no DNAPL was believed to be present. The results demonstrated no discernible pattern with depth for the four wells tested. A review of the data in light of the available technical literature suggests that the fine-grained nature of the aquifer materials precludes the formation of pools. Instead, DNAPL is trapped as discontinuous ganglia that are probably widespread throughout the aquifer. The discontinuous nature of the DNAPL distribution prevents the collection of groundwater samples with concentrations approaching saturation. Furthermore, the results indicate that attempts to remediate the aquifer with conventional approaches will not result in restoration to pristine conditions because the tortuous groundwater flow paths will inhibit the efficiency of fluid-flow-based treatments.

  18. Dissolution of dense non-aqueous phase liquids in vertical fractures: effect of finger residuals and dead-end pools.

    PubMed

    Yang, Zhibing; Niemi, Auli; Fagerlund, Fritjof; Illangasekare, Tissa; Detwiler, Russell L

    2013-06-01

    Understanding the dissolution behavior of dense non-aqueous phase liquids (DNAPLs) in rock fractures under different entrapment conditions is important for remediation activities and any related predictive modeling. This study investigates DNAPL dissolution in variable aperture fractures under two important entrapment configurations, namely, entrapped residual blobs from gravity fingering and pooling in a dead-end fracture. We performed a physical dissolution experiment of residual DNAPL blobs in a vertical analog fracture using light transmission techniques. A high-resolution mechanistic (physically-based) numerical model has been developed which is shown to excellently reproduce the experimentally observed DNAPL dissolution. We subsequently applied the model to simulate dissolution of the residual blobs under different water flushing velocities. The simulated relationship between the Sherwood number Sh and Peclet number Pe could be well fitted with a simple power-law function (Sh=1.43Pe⁰·⁴³). To investigate mass transfer from dead-end pools, another type of trapping in rock fractures, entrapment and dissolution of DNAPL in a vertical dead-end fracture was simulated. As the entrapped pool dissolves, the depth of the interface between the DNAPL and the flowing water increases linearly with decreasing DNAPL saturation. The interfacial area remains more or less constant as DNAPL saturation decreases, unlike in the case of residual DNAPL blobs. The decreasing depth of the contact interface changes the flow field and causes decreasing water flow velocity above the top of the DNAPL pool, suggesting the dependence of the mass transfer rate on the depth of the interface, or alternatively, the remaining mass percentage in the fracture. Simulation results show that the resultant Sherwood number Sh is significantly smaller than in the case of residual blobs for any given Peclet number, indicating slower mass transfer. The results also show that the Sh can be well

  19. The effect of spontaneous gas expansion and mobilization on the aqueous-phase concentrations above a dense non-aqueous phase liquid pool

    NASA Astrophysics Data System (ADS)

    Mumford, Kevin G.; Smith, James E.; Dickson, Sarah E.

    2010-04-01

    The spontaneous expansion and mobilization of discontinuous gas above dense non-aqueous-phase liquid (DNAPL) pools can affect the aqueous-phase concentrations of the DNAPL constituents above the pool. The results of an intermediate-scale, two-dimensional flow cell experiment showed that the discontinuous gas flow produced by spontaneous expansion, driven by the partitioning of 1,1,1-TCA from the surface of a DNAPL pool, resulted in detectable aqueous-phase concentrations of 1,1,1-TCA well above the pool surface. In comparison to a conventional model for DNAPL pool dissolution in the absence of a discontinuous gas phase, these concentrations were greater than expected, and were present at greater than expected elevations. Additionally, this study showed that the discontinuous gas flow produced transient behavior in the aqueous-phase concentrations, where the elevated concentrations occurred as short-term, pulse-like events. These results suggest that the spontaneous expansion and mobilization of discontinuous gas in DNAPL source zones could lead to the misdiagnosis of source zone architecture using aqueous concentration data, and that the transient nature of the elevated concentrations could further complicate the difficult task of source zone characterization.

  20. Comparison of iso-eluotropic mobile phases at different temperatures for the separation of triacylglycerols in Non-Aqueous Reversed Phase Liquid Chromatography.

    PubMed

    Hmida, Dorra; Abderrabba, Manef; Tchapla, Alain; Héron, Sylvie; Moussa, Fathi

    2015-05-15

    Triacylglycerols (TAGs) are a large class of neutral lipids that naturally occur in both plant and animal oils and fats. Their analyses in Non-Aqueous Reversed Phase Liquid Chromatography (NARP) require a mixture of weak solvent (mostly acetonitrile) and strong solvent. In the present work, we have established eluotropic solvent strength scale of several binary mobile phases on C18 bonded silica at different temperatures (acetonitrile/methylene chloride, acetonitrile/acetone, acetonitrile/ethyl acetate, acetonitrile/propan-2-ol, and acetonitrile/butan-1-ol at 25°C, 43°C, 63°C and 85°C); it is based on the methylene selectivity and the use of homologous series. We show that this scale is well suited to the TAGs analysis. The analysis of nine seed oils (Aleurites fordii, Calophyllum inophyllum, Glycina max, Olea europea, Orbignya olifeira, Pinus koraiensis, Pistacia lentiscus, Punica granatum and Ribes nigrum) in iso-eluotropic conditions leads to propose unambiguously the couple MeCN/BuOH at 25°C as the best system to separate TAGs. The use of butanol, as strong solvent, provides very good TAGs congeners separations and avoids the use of chlorinated solvents which gave to this day the best separations. PMID:25855317

  1. Ultra resolution chemical fingerprinting of dense non-aqueous phase liquids from manufactured gas plants by reversed phase comprehensive two-dimensional gas chromatography.

    PubMed

    McGregor, Laura A; Gauchotte-Lindsay, Caroline; Daéid, Niamh Nic; Thomas, Russell; Daly, Paddy; Kalin, Robert M

    2011-07-22

    Ultra resolution chemical fingerprinting of dense non-aqueous phase liquids (DNAPLs) from former manufactured gas plants (FMGPs) was investigated using comprehensive two-dimensional gas chromatography coupled with time of flight mass spectrometry (GC×GC TOFMS). Reversed phase GC×GC (i.e. a polar primary column coupled to a non-polar secondary column) was found to significantly improve the separation of polycyclic aromatic hydrocarbons (PAHs) and their alkylated homologues. Sample extraction and cleanup was performed simultaneously using accelerated solvent extraction (ASE), with recovery rates between 76% and 97%, allowing fast, efficient extraction with minimal solvent consumption. Principal component analysis (PCA) of the GC×GC data was performed in an attempt to differentiate between twelve DNAPLs based on their chemical composition. Correlations were discovered between DNAPL composition and historic manufacturing processes used at different FMGP sites. Traditional chemical fingerprinting methods generally follow a tiered approach with sample analysis on several different instruments. We propose ultra resolution chemical fingerprinting as a fast, accurate and precise method of obtaining more chemical information than traditional tiered approaches while using only a single analytical technique. PMID:21652041

  2. Laboratory characterization of non-aqueous phase liquid/tracer interaction in support of a vadose zone partitioning interwell tracer test

    NASA Astrophysics Data System (ADS)

    Deeds, Neil E.; McKinney, Daene C.; Pope, Gary A.

    2000-01-01

    Contaminant characterization is important for successful remediation of non-aqueous phase liquids (NAPLs) in the unsaturated zone. A partitioning interwell tracer test (PITT) can provide a good estimate of average subsurface NAPL saturations. Screening experiments were completed in the laboratory to evaluate several gas tracers for a PITT study to be completed in the vadose zone at Kirtland Air Force Base in Albuquerque, NM. Four perfluorocarbon tracers were found to be suitable for this PITT. Further laboratory column studies were completed using contaminated field soil to measure the partition coefficients between the tracers and the NAPL. The results from the column studies showed that the air/NAPL tracer partition coefficients ranged from 8.8±0.6 to 71±3. This range of partition coefficients is suitable for detection of NAPL saturations in the field of 0.002 to 0.14.

  3. Processes controlling the migration and biodegradation of Non-aqueous phase liquids (NAPLs) within fractured rocks in the vadose zone FY97 annual report

    SciTech Connect

    Geller, J.T.; Holman, Hoi-Ying; Conrad, M.

    1998-02-01

    Subsurface contamination from volatile organic compounds (VOCs) has been found at many Department of Energy (DOE), Department of Defense (DoD) and industrial sites due to the widespread use of organic solvents and hydrocarbon fuels. At ambient pressures and temperatures in the shallow subsurface, these substances are liquids that are immiscible with water; hence they are commonly designated as non-aqueous phase liquids (NAPLs). At some DOE sites, NAPLs are the presumed source of groundwater contamination in fractured rocks, such as basalts (at Hanford and Idaho National Engineering and Environmental Laboratory (INEEL)), shales (Oak Ridge Y-12 Plant), and welded tuffs (Los Alamos National Laboratory (LANL)). The flow, transport and biodegradation processes controlling NAPL behavior in the vadose zone must be understood in order to establish the possible extent of contamination, the risk to groundwater supplies, and appropriate remediation action. This is particularly important in and sites with deep water tables (such as at Hanford, INEEL and LANL). In fractured rock aquifers, NAPL migration is likely to be dominated by the highly permeable pathways provided by rock fractures and joints. Two- and three-phase fluid phases may be present in vadose zone fractures, including NAPL-gas, NAPL-water (in regions of perched water) and NAPL-water-gas.

  4. Retention behaviour of ceramides in sub-critical fluid chromatography in comparison with non-aqueous reversed-phase liquid chromatography.

    PubMed

    Gaudin, K; Lesellier, E; Chaminade, P; Ferrier, D; Baillet, A; Tchapla, A

    2000-06-23

    This study was devoted to the development of an analytical method for ceramide analysis in packed subcritical fluid chromatography (pSubFC). Monofunctional grafted silica support was found to be more suitable for ceramide analysis. Five Kromasil columns were coupled and the parameters, temperature, pressure and percentage of organic modifier in CO2 were optimised, considering selectivity and analysis time. The final conditions were 31 degrees C, 6% of methanol (MeOH) and 13 MPa. In these conditions the selectivity for structural differences (methylene group, unsaturation or two different bases) were studied. As classically observed, the methylene selectivity decreased with the increase of the eluotropic strength. Moreover, unlike in non-aqueous reversed-phase liquid chromatography (NARP-LC), adding a further unsaturation and two further methylene groups on ceramide results to an increase of retention in pSubFC. Moreover, this last technique allowed to separate ceramides with the same total number of carbons containing unsaturated fatty acids, when the distribution of carbon number of the two chain is very different. These results had enabled to plot retention chart in order to predict ceramide structure in view to identify additional ceramide. This retention chart was finally compared with the one already obtained in NARP-LC. PMID:10910215

  5. Postcolumn fluorescence as an alternative to evaporative light scattering detection for ceramide analysis with gradient elution in non-aqueous reversed-phase liquid chromatography.

    PubMed

    Zhou, J Y; Chaminade, P; Gaudin, K; Prognon, P; Baillet, A; Ferrier, D

    1999-10-22

    Ceramide analysis was developed with gradient elution in non-aqueous reversed-phase liquid chromatography with evaporative light scattering detection (ELSD) or postcolumn fluorescence detection. Fluorescence detection (excitation, 360 nm; emission, 425 nm) after postcolumn formation of mixed assemblies between eluted ceramides and 1,6-diphenyl-1,3,5-hexatriene was developed. In comparison with ELSD, fluorescence detection allows a better detection of the minor species ceramide from ceramide type III (commercial mixture of non-hydroxy fatty acid-sphingosine) and appears to be more sensitive for quantitation of ceramides at low concentrations. The fluorescence response is linear over a wide range of injected amount of ceramide III (expressed as stearoyl-phytosphingosine): 10 ng to 1000 ng. The response of ELSD is non linear but can be linearized in double logarithmic coordinates for calculations over a narrow range, e.g. between 10 to 350 ng ceramide III injected. The lower quantitation limits of these two detectors are similar: 5 ng ceramide III was injected. PMID:10563420

  6. Motile Geobacter dechlorinators migrate into a model source zone of trichloroethene dense non-aqueous phase liquid: Experimental evaluation and modeling

    NASA Astrophysics Data System (ADS)

    Philips, Jo; Miroshnikov, Alexey; Haest, Pieter Jan; Springael, Dirk; Smolders, Erik

    2014-12-01

    Microbial migration towards a trichloroethene (TCE) dense non-aqueous phase liquid (DNAPL) could facilitate the bioaugmentation of TCE DNAPL source zones. This study characterized the motility of the Geobacter dechlorinators in a TCE to cis-dichloroethene dechlorinating KB-1™ subculture. No chemotaxis towards or away from TCE was found using an agarose in-plug bridge method. A second experiment placed an inoculated aqueous layer on top of a sterile sand layer and showed that Geobacter migrated several centimeters in the sand layer in just 7 days. A random motility coefficient for Geobacter in water of 0.24 ± 0.02 cm2·day- 1 was fitted. A third experiment used a diffusion-cell setup with a 5.5 cm central sand layer separating a DNAPL from an aqueous top layer as a model source zone to examine the effect of random motility on TCE DNAPL dissolution. With top layer inoculation, Geobacter quickly colonized the sand layer, thereby enhancing the initial TCE DNAPL dissolution flux. After 19 days, the DNAPL dissolution enhancement was only 24% lower than with an homogenous inoculation of the sand layer. A diffusion-motility model was developed to describe dechlorination and migration in the diffusion-cells. This model suggested that the fast colonization of the sand layer by Geobacter was due to the combination of random motility and growth on TCE.

  7. The influence of a non-aqueous phase liquid (NAPL) and chemical oxidant application on perfluoroalkyl acid (PFAA) fate and transport.

    PubMed

    McKenzie, Erica R; Siegrist, Robert L; McCray, John E; Higgins, Christopher P

    2016-04-01

    One dimensional column experiments were conducted using saturated porous media containing residual trichloroethylene (TCE) to understand the effects of non-aqueous phase liquids (NAPLs) and chemical oxidation on perfluoroalkyl acid (PFAA) fate and transport. Observed retardation factors and data from supporting batch studies suggested that TCE provides additional sorption capacity that can increase PFAA retardation (i.e., decreased mobility), though the mechanisms remain unclear. Treatment with persulfate activated with FeCl2 and citric acid, catalyzed hydrogen peroxide (CHP), or permanganate did not result in oxidative transformations of PFAAs. However, impacts on PFAA sorption were apparent, and enhanced sorption was substantial in the persulfate-treated columns. In contrast, PFAA transport was accelerated in permanganate- and CHP-treated columns. Ultimately, PFAA transport in NAPL contaminated groundwater is likely influenced by porous media properties, NAPL characteristics, and water quality properties, each of which can change due to chemical oxidant treatment. For contaminated sites for which ISCO is a viable treatment option, changes to PFAA transport and the implications thereof should be included as a component of the remediation evaluation and selection process. PMID:26854608

  8. Influence of non-aqueous phase liquid configuration on induced polarization parameters: Conceptual models applied to a time-domain field case study

    NASA Astrophysics Data System (ADS)

    Johansson, Sara; Fiandaca, Gianluca; Dahlin, Torleif

    2015-12-01

    Resistivity and induced polarization (IP) measurements on soil contaminated with non-aqueous phase liquids (NAPLs) show a great variety in results in previous research. Several laboratory studies have suggested that the presence of NAPLs in soil samples generally decrease the magnitude of the IP-effect, while others have indicated the opposite. A number of conceptual models have been proposed suggesting that NAPLs can alter the pore space in different ways, e.g. by coating the grain surfaces and thus inhibiting grain polarization, or by changing the pore throat size and thus affecting the membrane polarization mechanism. The main aim of this paper is to review previously published conceptual models and to introduce some new concepts of possible residual NAPL configurations in the pore space. Time domain induced polarization measurements were performed at a NAPL contaminated field site, and the data were inverted using the Constant Phase Angle (CPA) model and the Cole-Cole model respectively. No significant phase anomalies were observed in the source area of the contamination when the CPA inverted profiles were compared with soil sampling results of free-phase contaminant concentrations. However, relatively strong phase and normalized phase anomalies appeared next to the source area, where residual free-phase presence could be expected according to the chemical data. We conclude that depending on the NAPL configuration, different spectral IP responses can be expected. In previous research, the NAPL configurations in different samples or field sites are often unknown, and this may to some extent explain why different results have been achieved by different authors. In our field case, we believe that the NAPL forms a more or less continuous phase in the pore space of the source zone leading to an absence of IP anomalies. The increase in phase and normalized phase angle observed next to the source zone is interpreted as a degradation zone. The ongoing biodegradation

  9. Evaluating Dense Non-Aqueous Phase Liquid Dissolution and Chemical Oxidation in a three-dimensional, bench-scale fracture network

    NASA Astrophysics Data System (ADS)

    Christensen, K.; McCray, J. E.; Schaefer, C.

    2011-12-01

    Dense non-aqueous phase liquid (DNAPL) present in fractured bedrock settings at residual saturation introduces remediation challenges that are dramatically different from porous media settings. Evaluating DNAPL distribution in a field-scale setting is generally impractical, yet DNAPL distribution plays a critical role in the DNAPL dissolution kinetics. This research uses a three-dimensional (3-D), bench-scale network comprised of low-porosity, fractured sandstone to evaluate the dissolution kinetics of tetrachloroethylene (PCE) DNAPL at residual saturation. DNAPL dissolution kinetics were evaluated during ambient groundwater conditions as well as during in situ chemical oxidation (ISCO) in the 3-D fractured sandstone experiment. DNAPL dissolution in the fracture network was evaluated and described using an effective parameter, the bulk mass transfer coefficient (KL). Results from dissolution experiments revealed a positive, statistically significant correlation between KL with DNAPL-water interfacial area and KL with DNAPL saturation. Results of ISCO experiments with potassium permanganate (KMnO4) determined that the formation of reaction products (manganese dioxides and carbon dioxide) likely altered the primary flow paths and decreased effectiveness of the ISCO application in the fracture network. The formation of reaction products was believed to cause flow bypassing and reduce the DNAPL-oxidant contact, which reduced mass transfer rates. The effectiveness of ISCO was improved (over dissolution alone) if the ISCO application was discontinued after an initial period of effective mass removal. The findings of this research indicate that DNAPL dissolution and oxidation effectiveness in a fracture network setting are not directly correlated to aperture size, which was unexpected, but appear to be primarily impacted by flow path variability and heterogeneous DNAPL distribution.

  10. Characterisation of dense non-aqueous phase liquids of coal tar using comprehensive two-dimensional gas chromatography coupled with time of flight mass spectrometry.

    NASA Astrophysics Data System (ADS)

    Gauchotte-Lindsay, Caroline; McGregor, Laura; Richards, Phil; Kerr, Stephanie; Glenn, Aliyssa; Thomas, Russell; Kalin, Robert

    2013-04-01

    Comprehensive two-dimensional gas chromatography (GCxGC) is a recently developed analytical technique in which two capillary columns with different stationary phases are placed in series enabling planar resolution of the analytes. The resolution power of GCxGC is one order of magnitude higher than that of one dimension gas chromatography. Because of its high resolution capacity, the use of GCxGC for complex environmental samples such as crude oils, petroleum derivatives and polychlorinated biphenyls mixtures has rapidly grown in recent years. We developed a one-step method for the forensic analysis of coal tar dense non-aqueous phase liquids (DNAPLs) from former manufactured gas plant (FMGP) sites. Coal tar is the by-product of the gasification of coal for heating and lighting and it is composed of thousands of organic and inorganic compounds. Before the boom of natural gases and oils, most towns and cities had one or several manufactured gas plants that have, in many cases, left a devastating environmental print due to coal tar contamination. The fate of coal tar DNAPLs, which can persist in the environment for more than a hundred years, is therefore of crucial interest. The presented analytical method consists of a unique clean-up/ extraction stage by pressurized liquid extraction and a single analysis of its organic chemical composition using GCxGC coupled with time of flight mass spectrometry (TOFMS). The chemical fingerprinting is further improved by derivatisation by N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) of the tar compounds containing -OH functions such as alcohols and carboxylic acids. We present here how, using the logical order of elution in GCxGC-TOFMS system, 1) the identification of never before observed -OH containing compounds is possible and 2) the isomeric selectivity of an oxidation reaction on a DNAPL sample can be revealed. Using samples collected at various FMGP sites, we demonstrate how this GCxGC method enables the simultaneous

  11. An environmental screening model to assess the consequences to soil and groundwater from railroad-tank-car spills of light non-aqueous phase liquids.

    PubMed

    Yoon, Hongkyu; Werth, Charles J; Barkan, Christopher P L; Schaeffer, David J; Anand, Pooja

    2009-06-15

    North American railroads transport a wide variety of chemicals, chemical mixtures and solutions in railroad tank cars. In the event of an accident, these materials may be spilled and impact the environment. Among the chemicals commonly transported are a number of light non-aqueous phase liquids (LNAPLs). If these are spilled they can contaminate soil and groundwater and result in costly cleanups. Railroads need a means of objectively assessing the relative risk to the environment due to spills of these different materials. Environmental models are often used to determine the extent of contamination, and the associated environmental risks. For LNAPL spills, these models must account for NAPL infiltration and redistribution, NAPL dissolution and volatilization, and remediation systems such as pump and treat. This study presents the development and application of an environmental screening model to assess NAPL infiltration and redistribution in soils and groundwater, and to assess groundwater cleanup time using a pumping system. Model simulations use parameters and conditions representing LNAPL releases from railroad tank cars. To take into account unique features of railroad-tank-car spill sites, the hydrocarbon spill screening model (HSSM), which assumes a circular surface spill area and a circular NAPL lens, was modified to account for a rectangular spill area and corresponding lens shape at the groundwater table, as well as the effects of excavation and NAPL evaporation to the atmosphere. The modified HSSM was first used to simulate NAPL infiltration and redistribution. A NAPL dissolution and groundwater transport module, and a pumping system module were then implemented and used to simulate the effects of chemical properties, excavation, and free NAPL removal on NAPL redistribution and cleanup time. The amount of NAPL that reached the groundwater table was greater in coarse sand with high permeability than in fine sand or silt with lower permeabilities

  12. Non-aqueous-phase fluids in heterogeneous aquifers -- experimental study

    SciTech Connect

    Illangasekare, T.H.; Yates, D.N.; Armbruster, E.J. III.

    1995-08-01

    Understanding of flow and entrapment of non-aqueous-phase liquids (NAPLs) in aquifers contaminated with organic chemicals is important in the effective design of recovery and remediation schemes. Soil heterogeneities play a significant role in the physical behavior of these chemicals. An experimental facility consisting of a large soil tank (lysimeter) and a dual-gamma spectroscopy system for fluid saturation measurements was developed to simulate and monitor plume migration in water-table aquifers after chemical spills. Experimental techniques and results form a preliminary set of experiments conducted in unsaturated and saturated soils under homogeneous and heterogeneous conditions are presented. the effects of the layered homogeneities were pronounced in modifying the migration pattern and velocity of the plume. Pockets of coarse sand placed across the path of the plume resulted in the soil acting as a light NAPL trap. A fine-sand pocket acted as a barrier. Qualitative and quantitative data generated in the type of experiments presented in this paper can be used to validate multiphase flow models.

  13. Non-aqueous emulsions stabilized by block copolymers: application to liquid disinfectant-filled elastomeric films.

    PubMed

    Riess, Gérard; Cheymol, André; Hoerner, Pierre; Krikorian, Raffi

    2004-05-20

    The emulsifying and stabilization efficiency of polybutadiene-b-poly(ethylene oxide) and poly(ter butylstyrene)-poly(ethylene oxide) diblock copolymers is examined in non-aqueous emulsions. These emulsions are formed by a dispersion of polyethylene glycol mixed with a cationic surfactant acting as a biocide, in a continuous phase of a thermoplastic elastomer (SEBS) dissolved in methylcyclohexane. Emulsions with controlled droplet size and excellent stability could be obtained, which by solvent evaporation lead to elastomeric films containing droplets of confined disinfecting liquids. PMID:15072927

  14. Alkyl-bis(imidazolium) salts: a new amphiphile platform that forms thermotropic and non-aqueous lyotropic bicontinuous cubic phases

    SciTech Connect

    Robertson, LA; Schenkel, MR; Wiesenauer, BR; Gin, DL

    2013-01-01

    New ionic amphiphiles with a hexyl-bridged bis(imidazolium) headgroup; Br-, BF4-, or Tf2N- anions; and a long n-alkyl tail can form thermotropic bicontinuous cubic liquid crystal phases in neat form and/or lyotropic bicontinuous cubic phases with several non-aqueous solvents or water.

  15. Making non-aqueous high internal phase pickering emulsions: influence of added polymer and selective drying.

    PubMed

    Cai, Dongyu; Thijssen, Job H T; Clegg, Paul S

    2014-06-25

    We report the first example of a non-aqueous (oil-in-oil) Pickering high internal phase emulsion (HIPE) stabilized by chemically modified fumed silica. In this case, a 75 vol % ethylene carbonate (EC)-rich internal phase is emulsified in 25 vol % p-xylene (xylene)-rich continuous phase using interfacial nanoparticles. It is revealed that no phase inversion takes place during the HIPE formation process when using the appropriate wettability of solid particles. Incorporating polystyrene (PS) into xylene enables one-step formation of PS-filled HIPEs in place of a multi-step polymerization of the continuous phase. We observe that the size of droplets changes with the addition of PS, and we associate this with the change in the viscosity of the continuous xylene-rich phase. Drying the pure HIPE results in the selective removal of xylene and coalescence of EC-rich droplets. With the PS in the xylene-rich continuous phase, we show that EC-rich droplets can be retained even though the xylene is evaporated off, and a new semi-solid composite containing both liquid phase and solid phase is formed via this non-aqueous Pickering-HIPE template. PMID:24865657

  16. Partition behavior of surfactants, butanol, and salt during application of density-modified displacement of dense non-aqueous phase liquids.

    PubMed

    Damrongsiri, S; Tongcumpou, C; Sabatini, D A

    2013-03-15

    Density-modified displacement (DMD) is a recent approach for removal of trapped dense NAPL (DNAPL). In this study, butanol and surfactant are contacted with the DNAPL to both reduce the density as well as release the trapped DNAPL (perchloroethylene: PCE). The objective of the study was to determine the distribution of each component (e.g., butanol, surfactant, water, PCE) between the original aqueous and PCE phases during the application of DMD. The results indicated that the presence of the surfactant increased the amount of n-butanol required to make the NAPL phase reach its desired density. In addition, water and anionic surfactant were found to partition along with the BuOH into the PCE phase. The water also found partitioned to reverse micelles in the modified phase. Addition of salt was seen to increase partitioning of surfactant to BuOH containing PCE phase. Subsequently, a large amount of water was solubilized into reverse micelles which lead to significantly increase in volume of the PCE phase. This work thus demonstrates the role of each component and the implications for the operation design of an aquifer treatment using the DMD technique. PMID:23385206

  17. Effects of capillary pressure and use of polymer solutions on dense, non-aqueous-phase liquid retention and mobilization in a rough-walled fracture

    SciTech Connect

    Longino, B.L.; Kueper, B.H. . Dept. of Civil Engineering)

    1999-07-15

    In this laboratory study, perchloroethylene (PCE) was permitted to migrate through a horizontal rough-walled limestone fracture under controlled conditions to assess fracture retention capacity. Retention of immiscible-phase PCE in the absence of an applied wetting-phase hydraulic gradient varied between 11% and 26% of the fracture volume. A portion of this residual could be removed through water flooding; however, even at the maximum applied hydraulic gradient of 1.0, residual PCE remained in the fracture. The observed correlation of reduced residual saturation with capillary number (N[sub c]) demonstrated that this rough-walled fracture exhibited behavior similar to that of a porous medium under water-flooding conditions. For a given hydraulic gradient, polymer-enhanced floods (using xanthan gum) were not as successful as conventional water flooding at removing residual from the fracture. The traditional form of the capillary number became an increasingly poor predictor of mobilization behavior as the viscosity of the displacing phase was increased. Incorporation of ([mu][sub w]/[mu][sub nw])[sup [minus]0.5] into the traditional capillary number provided a more appropriate dimensionless group with which to correlate residual PCE saturation in the fracture as [mu][sub w] increased.

  18. Processes controlling the migration and biodegradation of non-aqueous phase liquids (NAPLs) within fractured rocks in the vadose zone. FY96 annual report

    SciTech Connect

    Geller, J.T.; Holman, H.Y.; Conrad, M.; Pruess, K.; Hunter-Cevera, J.C.; Su, G.

    1997-02-01

    This project investigates both flow dynamics and microbial processes affecting NAPLs in fractured rock in a closely coupled, integrated manner. The objective is to develop a qualitative and quantitative understanding of the behavior of two and three immiscible fluid phases, microbial transformation and/or degradation, and to provide a scientific basis for field investigations, site characterization, and remedial action for NAPL contamination in fractured rocks. To achieve this, the program combines laboratory and theoretical investigations, coupled with the evaluation of conditions at relevant field sites. This report summarizes the work accomplished since inception of the project in April 1996.

  19. Improving the treatment of non-aqueous phase TCE in low permeability zones with permanganate.

    PubMed

    Chokejaroenrat, Chanat; Comfort, Steve; Sakulthaew, Chainarong; Dvorak, Bruce

    2014-03-15

    Treating dense non-aqueous phase liquids (DNAPLs) embedded in low permeability zones (LPZs) is a particularly challenging issue for injection-based remedial treatments. Our objective was to improve the sweeping efficiency of permanganate (MnO4(-)) into LPZs to treat high concentrations of TCE. This was accomplished by conducting transport experiments that quantified the penetration of various permanganate flooding solutions into a LPZ that was spiked with non-aqueous phase (14)C-TCE. The treatments we evaluated included permanganate paired with: (i) a shear-thinning polymer (xanthan); (ii) stabilization aids that minimized MnO2 rind formation and (iii) a phase-transfer catalyst. In addition, we quantified the ability of these flooding solutions to improve TCE destruction under batch conditions by developing miniature LPZ cylinders that were spiked with (14)C-TCE. Transport experiments showed that MnO4(-) alone was inefficient in penetrating the LPZ and reacting with non-aqueous phase TCE, due to a distinct and large MnO2 rind that inhibited the TCE from further oxidant contact. By including xanthan with MnO4(-), the sweeping efficiency increased (90%) but rind formation was still evident. By including the stabilization aid, sodium hexametaphosphate (SHMP) with xanthan, permanganate penetrated 100% of the LPZ, no rind was observed, and the percentage of TCE oxidized increased. Batch experiments using LPZ cylinders allowed longer contact times between the flooding solutions and the DNAPL and results showed that SHMP+MnO4(-) improved TCE destruction by ∼16% over MnO4(-) alone (56.5% vs. 40.1%). These results support combining permanganate with SHMP or SHMP and xanthan as a means of treating high concentrations of TCE in low permeable zones. PMID:24491441

  20. Modelling of ceramide interactions with porous graphite carbon in non-aqueous liquid chromatography.

    PubMed

    West, C; Cilpa, G; Gaudin, K; Chaminade, P; Lesellier, E

    2005-09-16

    Interactions of solutes on porous graphitic carbon (PGC) with non-aqueous mobile phases are studied by the linear solvation energy relationship (LSER). Studies have been carried out with eight binary mixtures composed of a weak solvent (acetonitrile or methanol) and a strong solvent (tetrahydrofuran, n-butanol, CH2Cl2, 1,1,2-trichloro-2,2,1-trifluoroethane). The systematic analysis of a set of test compounds was performed for each solvent mixture in isocratic mode (50:50). The results were compared to those obtained on PGC with hydro-organic liquids and supercritical fluids. They were then correlated with the observed retention behaviour of lipid compounds, more particularly ceramides. PMID:16130700

  1. Growth and development in inert non-aqueous liquids. [of higher plants

    NASA Technical Reports Server (NTRS)

    Siegel, S. M.

    1974-01-01

    A preview is presented of the survival and growth capabilities of higher plants in non-aqueous, inert liquids. The two media which were used are mineral (white) oil and fluorochemical inert liquid FC-75. Both liquids dissolve oxygen and carbon dioxide readily, but are insoluble in water. Consequently, plants submerged in these liquids are capable of gas exchange with the atmosphere, but possess a water impermeable coating the dimensions of which are determined by the size of the liquid holding container. In a sense, growing plants in a tank of mineral oil imparts on them a cuticle. Plants plus prescribed volumes of water were innoculated into mineral oil. Organisms with minimal water supplied could then be observed. Also, submersed plants covered with an oil slick were shown to be capable of growth in dessicating atmospheres.

  2. Expanded separation technique for chlorophyll metabolites in Oriental tobacco leaf using non aqueous reversed phase chromatography.

    PubMed

    Ishida, Naoyuki

    2011-08-26

    An improved separation method for chlorophyll metabolites in Oriental tobacco leaf was developed. While Oriental leaf still gives the green color even after the curing process, little attention has been paid to the detailed composition of the remaining green pigments. This study aimed to identify the green pigments using non aqueous reversed phase chromatography (NARPC). To this end, liquid chromatograph (LC) equipped with a photo diode array detector (DAD) and an atmospheric pressure chemical ionization/mass spectrometer (APCI/MSD) was selected, because it is useful for detecting low polar non-volatile compounds giving green color such as pheophytin a. Identification was based on the wavelength spectrum, mass spectrum and retention time, comparing the analytes in Oriental leaf with the commercially available and synthesized components. Consequently, several chlorophyll metabolites such as hydroxypheophytin a, solanesyl pheophorbide a and solanesyl hydroxypheophorbide a were newly identified, in addition to typical green pigments such as chlorophyll a and pheophytin a. Chlorophyll metabolites bound to solanesol were considered the tobacco specific components. NARPC expanded the number of detectable low polar chlorophyll metabolites in Oriental tobacco leaf. PMID:21782189

  3. Eluotropic strength in non-aqueous liquid chromatography with porous graphitic carbon.

    PubMed

    Gaudin, Karen; Chaminade, Pierre; Baillet, Arlette

    2002-10-11

    Porous graphitic carbon is an attractive packing for the chromatographic analysis of highly hydrocarbonaceous compounds with non-aqueous mobile phase. An eluotropic-strength scale of 10 pure organic solvents was established using the methylene selectivity from the fatty acid methyl ester homologous series (chain length between 18 and 31 carbon atoms). Eight binary mobile phases combining a weak solvent: methanol or acetonitrile with a strong solvent: toluene, chloroform, dichloromethane or tetrahydrofuran at different volume fractions phi of strong solvents (ranging from 0.3 to 1.0) were tested and their eluotropic strengths were then compared with those of pure solvents. The curves of the eluotropic strength versus the volume fraction of the strong solvent followed two different trends: linear or curved. The knowledge of the pure solvent strength is not sufficient to predict the eluotropic strength of solvent in the mixture. Then modelling of the eluotropic strength for binary mobile phases was envisaged in order to provide a prediction tool. This model was assessed for the establishment of the composition of eight iso-eluotropic mobile phases. Good assessment was found except in the case of toluene with acetonitrile where the difference between the predicted and the real value was the highest. PMID:12437164

  4. Ion transport properties of magnesium bromide/dimethyl sulfoxide non-aqueous liquid electrolyte

    PubMed Central

    Sheha, E.

    2015-01-01

    Nonaqueous liquid electrolyte system based dimethyl sulfoxide DMSO and magnesium bromide (MgBr2) is synthesized via ‘Solvent-in-Salt’ method for the application in magnesium battery. Optimized composition of MgBr2/DMSO electrolyte exhibits high ionic conductivity of 10−2 S/cm at ambient temperature. This study discusses different concentrations from 0 to 5.4 M of magnesium salt, representing low, intermediate and high concentrations of magnesium salt which are examined in frequency dependence conductivity studies. The temperature dependent conductivity measurements have also been carried out to compute activation energy (Ea) by least square linear fitting of Arrhenius plot: ‘log σ − 1/T. The transport number of Mg2+ ion determined by means of a combination of d.c. and a.c. techniques is ∼0.7. A prototype cell was constructed using nonaqueous liquid electrolyte with Mg anode and graphite cathode. The Mg/graphite cell shows promising cycling. PMID:26843967

  5. New methods and materials for solid phase extraction and high performance liquid chromatography

    SciTech Connect

    Dumont, P.J.

    1996-04-23

    This paper describes methods for solid phase extraction and high performance liquid chromatography (HPLC). The following are described: Effects of Resin Sulfonation on the Retention of Polar Organic Compounds in Solid Phase Extraction; Ion-Chromatographic Separation of Alkali Metals In Non-Aqueous Solvents; Cation-Exchange Chromatography in Non-Aqueous Solvents; and Silicalite As a Stationary Phase For HPLC.

  6. Non-Aqueous Capillary Electrophoresis

    NASA Astrophysics Data System (ADS)

    Szumski, Michał; Buszewski, Bogusław

    Non-aqueous capillary electrophoresis and capillary electrochromatography are special variants of these techniques. Here, organic solvents or their mixtures with or without dissolved electrolytes are used as separation buffer or mobile phase, respectively. The most important features of non-aqueous systems are: better solubility of more hydrophobic ionic substances (many natural products) than in water, much less current and Joule heating allows for using highly concentrated buffers and/or larger capillary internal diameters, polar interactions are enhanced in organic solvents which is often highly advantageous in chiral separation systems. This chapter presents most frequently used solvents, their properties, as well as shows pH* scale which is often used in non-aqueous systems.

  7. Bioenhanced dissolution of dense non-aqueous phase of trichloroethylene as affected by iron reducing conditions: model systems and environmental samples.

    PubMed

    Paul, Laiby; Smolders, Erik

    2015-01-01

    The anaerobic biotransformation of trichloroethylene (TCE) can be affected by competing electron acceptors such as Fe (III). This study assessed the role of Fe (III) reduction on the bioenhanced dissolution of TCE dense non-aqueous phase liquid (DNAPL). Columns were set up as 1-D diffusion cells consisting of a lower DNAPL layer, a layer with an aquifer substratum and an upper water layer that is regularly refreshed. The substrata used were either inert sand or sand coated with 2-line ferrihydrite (HFO) or two environmental Fe (III) containing samples. The columns were inoculated with KB-1 and were repeatedly fed with formate. In none of the diffusion cells, vinyl chloride or ethene was detected while dissolved and extractable Fe (II) increased strongly during 60 d of incubation. The cis-DCE concentration peaked at 4.0 cm from the DNAPL (inert sand) while it was at 3.4 cm (sand+HFO), 1.7 cm and 2.5 cm (environmental samples). The TCE concentration gradients near the DNAPL indicate that the DNAPL dissolution rate was larger than that in an abiotic cell by factors 1.3 (inert sand), 1.0 (sand+HFO) and 2.2 (both environmental samples). This results show that high bioavailable Fe (III) in HFO reduces the TCE degradation by competitive Fe (III) reduction, yielding lower bioenhanced dissolution. However, Fe (III) reduction in environmental samples was not reducing TCE degradation and the dissolution factor was even larger than that of inert sand. It is speculated that physical factors, e.g. micro-niches in the environmental samples protect microorganisms from toxic concentrations of TCE. PMID:25460750

  8. Literature search for the non-aqueous separation of zinc from fuel rod cladding. [After dissolution in liquid metal

    SciTech Connect

    Sandvig, R. L.; Dyer, S. J.; Lambert, G. A.; Baldwin, C. E.

    1980-06-21

    This report reviews the literature of processes for the nonaqueous separation of zinc from dissolved fuel assembly cladding. The processes considered were distillation, pyrochemical processing, and electrorefining. The last two techniques were only qualitatively surveyed while the first, distillation, was surveyed in detail. A survey of available literature from 1908 through 1978 on the distillation of zinc was performed. The literature search indicated that a zinc recovery rate in excess of 95% is possible; however, technical problems exist because of the high temperatures required and the corrosive nature of liquid zinc. The report includes a bibliography of the surveyed literature and a computer simulation of vapor pressures in binary systems. 129 references.

  9. In-Situ Characterization of Dense Non-Aqueous Phase Liquids Using Partitioning Tracers

    SciTech Connect

    Gary A. Pope; Daene C. McKinney; Akhil Datta Gupta; Richard E. Jackson; Minquan Jin

    2000-03-20

    Majors advances have been made during the past three years in our research on interwell partitioning tracers tests (PITTs). These advances include (1) progress on the inverse problem of how to estimate the three-dimensional distribution of NAPL in aquifers from the tracer data, (2) the first ever partitioning tracer experiments in dual porosity media, (3) the first modeling of partitioning tracers in dual porosity media (4) experiments with complex NAPLs such as coal tar, (5) the development of an accurate and simple method to predict partition coefficients using the equivalent alkane carbon number approach, (6) partitioning tracer experiments in large model aquifers with permeability layers, (7) the first ever analysis of partitioning tracer data to estimate the change in composition of a NAPL before and after remediation (8) the first ever analysis of partitioning tracer data after a field demonstration of surfactant foam to remediate NAPL and (9) experiments at elevated temperatures .

  10. VISUALIZATION AND SIMULATION OF NON-AQUEOUS PHASE LIQUIDS SOLUBILIZATION IN PORE NETWORKS

    EPA Science Inventory

    The design of in-situ remediation of contaminated soils is mostly based on a description at the macroscopic scale using a averaged quantities. These cannot address issues at the pore and pore network scales. In this paper, visualization experiments and numerical simulations in ...

  11. DEMONSTRATION OF STEAM HEATING FOR REMEDIATION OF DENSE NON-AQUEOUS PHASE LIQUID (DNAPL)

    EPA Science Inventory

    Several technologies were used to evaluate their performances in removing the source of DNAPL, chlorinated solvents, such as trichloroethylene (TCE), from Launch Complex 34, Cape Canaveral Air Station. This project evaluated steam injection as a remediation technology.

  12. EXPERIMENTAL EVALUATION OF TWO SHARP FRONT MODELS FOR VADOSE ZONE NON-AQUEOUS PHASE LIQUID TRANSPORT

    EPA Science Inventory

    Recent research efforts on the transport of immiscible organic wastes in subsurface the development of numerical models of various levels of sophistication. Systems have focused on the site characterization data needed to obtain. However, in real field applications, the model p...

  13. SYNTHESIS REPORT ON FIVE DENSE, NONAQUEOUS-PHASE LIQUID (DNAPL) REMEDIATION PROJECTS

    EPA Science Inventory

    Dense non-aqueous phase liquid (DNAPL) poses a difficult problem for subsurface remediation because it serves as a continuing source to dissolved phase ground water contamination and is difficult to remove from interstitial pore space or bedrock fractures in the subsurface. Numer...

  14. LIGHT NONAQUEOUS PHASE LIQUIDS

    EPA Science Inventory

    Nonaqueous phase liquids (NAPLS) are hydrocarbons that exist as a separate, immiscible phase when in contact with water and/or air. ifferences in the physical and chemical properties of water and NAPL result in the formation of a physical interface between the liquids which preve...

  15. Aquitard contaminant storage and flux resulting from dense nonaqueous phase liquid source zone dissolution and remediation

    EPA Science Inventory

    A one-dimensional diffusion model was used to investigate the effects of dense non-aqueous phase liquid (DNAPL) source zone dissolution and remediation on the storage and release of contaminants from aquitards. Source zone dissolution was represented by a power-law source depleti...

  16. Non-aqueous electrochemical cell

    SciTech Connect

    Blomgren, G.E.; Kronenberg, M.L.

    1983-08-23

    The invention relates to the use in a non-aqueous electrochemical cell of an electrolyte comprising a solute dissolved in a solvent which is an oxyhalide of an element of Group V or Group VI of the Periodic Table. The oxyhalide solvent serves the dual function of acting as the solvent for the electrolyte salt and as the active cathode depolarizer of the cell.

  17. Non-aqueous electrochemical cell

    SciTech Connect

    Blomgren, G.E.; Kronenberg, M.L.

    1984-04-24

    The invention relates to the use in a non-aqueous electrochemical cell of a conductive electrolyte comprising an ionizing solute dissolved in a mixture of a selected halide of an element of Group IV to Group VI of the Periodic Table and a cosolvent. The selected halide serves the dual function of acting as a solvent for the solute and as the active cathode depolarizer of the cell.

  18. Organic non-aqueous cation-based redox flow batteries

    DOEpatents

    Jansen, Andrew N.; Vaughey, John T.; Chen, Zonghai; Zhang, Lu; Brushett, Fikile R.

    2016-03-29

    The present invention provides a non-aqueous redox flow battery comprising a negative electrode immersed in a non-aqueous liquid negative electrolyte, a positive electrode immersed in a non-aqueous liquid positive electrolyte, and a cation-permeable separator (e.g., a porous membrane, film, sheet, or panel) between the negative electrolyte from the positive electrolyte. During charging and discharging, the electrolytes are circulated over their respective electrodes. The electrolytes each comprise an electrolyte salt (e.g., a lithium or sodium salt), a transition-metal free redox reactant, and optionally an electrochemically stable organic solvent. Each redox reactant is selected from an organic compound comprising a conjugated unsaturated moiety, a boron cluster compound, and a combination thereof. The organic redox reactant of the positive electrolyte is selected to have a higher redox potential than the redox reactant of the negative electrolyte.

  19. Non-aqueous Isorefractive Pickering Emulsions.

    PubMed

    Thompson, Kate L; Lane, Jacob A; Derry, Matthew J; Armes, Steven P

    2015-04-21

    Non-aqueous Pickering emulsions of 16-240 μm diameter have been prepared using diblock copolymer worms with ethylene glycol as the droplet phase and an n-alkane as the continuous phase. Initial studies using n-dodecane resulted in stable emulsions that were significantly less turbid than conventional water-in-oil emulsions. This is attributed to the rather similar refractive indices of the latter two phases. By utilizing n-tetradecane as an alternative oil that almost precisely matches the refractive index of ethylene glycol, almost isorefractive ethylene glycol-in-n-tetradecane Pickering emulsions can be prepared. The droplet diameter and transparency of such emulsions can be systematically varied by adjusting the worm copolymer concentration. PMID:25844544

  20. Non-aqueous Isorefractive Pickering Emulsions

    PubMed Central

    2015-01-01

    Non-aqueous Pickering emulsions of 16–240 μm diameter have been prepared using diblock copolymer worms with ethylene glycol as the droplet phase and an n-alkane as the continuous phase. Initial studies using n-dodecane resulted in stable emulsions that were significantly less turbid than conventional water-in-oil emulsions. This is attributed to the rather similar refractive indices of the latter two phases. By utilizing n-tetradecane as an alternative oil that almost precisely matches the refractive index of ethylene glycol, almost isorefractive ethylene glycol-in-n-tetradecane Pickering emulsions can be prepared. The droplet diameter and transparency of such emulsions can be systematically varied by adjusting the worm copolymer concentration. PMID:25844544

  1. Review on mechanisms and continuum models of multi-phase transport phenomena in porous structures of non-aqueous Li-Air batteries

    NASA Astrophysics Data System (ADS)

    Yuan, Jinliang; Yu, Jong-Sung; Sundén, Bengt

    2015-03-01

    During recent years intensive research activities involving both experimental and modeling approaches have appeared for different aspects of Lithium-air (Li-air) battery. Multi-phase transport phenomena including dissolved oxygen and lithium ions (Li+) in the liquid electrolyte, as well as electrons in the solid materials, are strongly coupled with the porous structures and various reactions, particularly the solid product grown in the porous cathode during battery discharge. Understanding the mechanisms of transport phenomena and accurate evaluation of effective transport properties are significant for improving the battery capacities and design, especially at high rate conditions. In this paper, the transport governing equations commonly used for macroscopic continuum models at porous-average level are outlined and highlighted, with a purpose to provide a general overview of the validity and the limitation of these approaches. The most often used models in the open literature are reviewed and discussed focusing on the effective properties involving tortuosity factors, solid product morphologies, as well as effects on the void space clogging, surface area reduction and passivation. Comments and suggestions are also provided for better understanding of multi-phase transport phenomena and implementation of the detailed models for solid product generation and morphology growth in Li-air battery cathodes.

  2. Ionic liquids as electrolytes for non-aqueous solutions electrochemical supercapacitors in a temperature range of 20 °C-80 °C

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Tsay, Ken; Bock, Christina; Zhang, Jiujun

    2016-08-01

    To increase the operating temperature of the supercapacitors (SCs) without compromising their high cycle-life, several typical fluoro- and non-fluoro containing ionic liquids (EMI-mesylate, EMI-hydrogen sulfate, PP13-triflate, PP13-TFSI, and EMI-TFSI, as shown in Fig. 1) are studied as the electrolytes to prepare organic solutions for SC performance measurements using a two-electrode cell. Both cyclic voltammograms and charge/discharge curves at various temperatures such as 20, 40, 60 and 80 °C are collected. At 60 °C, the increased performance order in both rating and cyclability measurements are found to be as follows: 1) EMI-hydrogen sulfate < PP13-TFSI < EMI-mesylate < PP13-triflate < EMI-TFSI for rating; and 2) EMI-hydrogen sulfate < EMI-mesylate < PP13-Triflate < PP13-TFSI < EMI-TFSI for life-time. The fluoro-containing group of ILs, i.e., PP13-Triflate, PP13-TFSI and EMI-TFSI can give a specific capacitance between 100 and 170 F/g for various scan rates for a conventional carbon electrode, and an extended lifetime test of 10, 000 cycles with a capacitance degradation of less than 10%, indicating that these two ion liquids can be used for SC electrolytes operated at high temperature.

  3. Effects of a Protic Ionic Liquid on the Reaction Pathway during Non-Aqueous Sol–Gel Synthesis of Silica: A Raman Spectroscopic Investigation

    PubMed Central

    Martinelli, Anna

    2014-01-01

    The reaction pathway during the formation of silica via a two-component “non-aqueou” sol-gel synthesis is studied by in situ time-resolved Raman spectroscopy. This synthetic route is followed with and without the addition of the protic ionic liquid 1-ethylimidazolium bis(trifluoromethanesulfonyl)imide (C2HImTFSI) in order to investigate its effect on the reaction pathway. We demonstrate that Raman spectroscopy is suitable to discriminate between different silica intermediates, which are produced and consumed at different rates with respect to the point of gelation. We find that half-way to gelation monomers and shorter chains are the most abundant silica species, while the formation of silica rings strongly correlates to the sol-to-gel transition. Thus, curling up of linear chains is here proposed as a plausible mechanism for the formation of small rings. These in turn act as nucleation sites for the condensation of larger rings and thus the formation of the open and polymeric silica network. We find that the protic ionic liquid does not change the reaction pathway per se, but accelerates the cyclization process, intermediated by the faster inclusion of monomeric species. PMID:24743891

  4. In-situ characterization of dense non-aqueous phase liquids uUsing partitioning tracers. 1998 annual progress report

    SciTech Connect

    Pope, G.A.

    1998-06-01

    'Major advances have been made during the past year in research on interwell partitioning tracers tests (PITTs). These advances include: (1) progress on the inverse problem of how to estimate the three-dimensional distribution of NAPL in aquifers from the tracer data, (2) the first ever partitioning tracer experiments in dual porosity media, (3) the first modeling of partitioning tracers in dual porosity media, (4) experiments with complex NAPLs such as coal tar, (5) the development of an accurate and simple method to predict partition coefficients using the equivalent alkane carbon number approach, (6) partitioning tracer experiments in large model aquifers with permeability layers, (7) the first ever analysis of partitioning tracer data to estimate the change in composition of a NAPL before and after remediation, (8) the first ever analysis of partitioning tracer data after a field demonstration of surfactant foam to remediate NAPL, and (9) experiments at elevated temperatures. The authors have developed a new analytic approach that has several advantages over existing approaches for inversion of tracer data. First, the technique utilizes an extremely efficient three-dimensional multiphase streamline simulator as a forward model. Second, the parameter sensitivities are formulated in terms of one-dimensional integrals of analytic functions along the streamlines. Thus, the computation of sensitivities for all model parameters requires only a single simulation run to construct the velocity field and generate the streamlines. The inversion of tracer data is then performed using a two-step iterative linearization that involves first lining-up the breakthrough times at the producing wells and then matching the production history. Their approach follows from an analogy between streamlines and ray tracing in seismology. The inverse method is analogous to seismic waveform inversion and thus, allows them to utilize efficient methods from geophysical imaging. The new approach has been applied for estimating permeability distribution based on conservative tracer tests (D.W. Vasco and A. Datta-Gupta: ``Asymptotic Solutions for Solute Transport: A Formalism for Tracer Tomography,'''' Submitted to Water Resources Research, December 1997), and is currently being extended for analysis of partitioning tracer data.'

  5. Hot air injection for removal of dense, non-aqueous-phase liquid contaminants from low-permeability soils

    SciTech Connect

    Payne, F.C.

    1996-08-01

    The performance of soil vapor extraction systems for the recovery of volatile and semi-volatile organic compounds is potentially enhanced by the injection of heated air to increase soil temperatures. The soil temperature increase is expected to improve soil vapor extraction (SVE) performance by increasing target compound vapor pressures and by increasing soil permeability through drying. The vapor pressure increase due to temperature rise relieves the vapor pressure limit on the feasibility of soil vapor extraction. However, the system still requires an air flow through the soil system to deliver heat and to recover mobilized contaminants. Although the soil permeability can be increased through drying, very low permeability soils and low permeability soils adjacent to high permeability air flow pathways will be treated slowly, if at all. AR thermal enhancement methods face this limitation. Heated air injection offers advantages relative to other thermal techniques, including low capital and operation costs. Heated air injection is at a disadvantage relative to other thermal techniques due to the low heat capacity of air. To be effective, heated air injection requires that higher air flows be established than for steam injection or radio frequency heating. Heated air injection is not economically feasible for the stratified soil system developed as a standard test for this document. This is due to the inability to restrict heated air flow to the clay stratum when a low-resistance air flow pathway is available in the adjoining sand. However, the technology should be especially attractive, both technically and economically, for low-volatile contaminant recovery from relatively homogeneous soil formations. 16 refs., 2 tabs.

  6. Electric field induced birefringence in non-aqueous dispersions of mineral nanorods.

    PubMed

    de la Cotte, Alexis; Merzeau, Pascal; Kim, Jong Wook; Lahlil, Khalid; Boilot, Jean-Pierre; Gacoin, Thierry; Grelet, Eric

    2015-09-01

    Lanthanum phosphate (LaPO4) nanorods dispersed in the non-aqueous solvent of ethylene glycol form a system exhibiting large intrinsic birefringence, high colloidal stability and the ability to self-organize into liquid crystalline phases. In order to probe the electro-optical response of these rod dispersions we study here the electric-field-induced birefringence, also called Kerr effect, for a concentrated isotropic liquid state with an in-plane a.c. sinusoidal electric field, in conditions of directly applied (electrodes in contact with the sample) or externally applied (electrodes outside the sample cell) fields. Performing an analysis of the electric polarizability of our rod-like particles in the framework of Maxwell-Wagner-O'Konski theory, we account quantitatively for the coupling between the induced steady-state birefringence and the electric field as a function of the voltage frequency for both sample geometries. The switching time of this non-aqueous transparent system has been measured, and combined with its high Kerr coefficients and its features of optically isotropic "off-state" and athermal phase behavior, this represents a promising proof-of-concept for the integration of anisotropic nanoparticle suspensions into a new generation of electro-optical devices. PMID:26189711

  7. PHASE CHANGE LIQUIDS

    SciTech Connect

    Susan S. Sorini; John F. Schabron

    2006-03-01

    Work is being performed to develop a new shipping system for frozen environmental samples (or other materials) that uses an optimal phase change liquid (PCL) formulation and an insulated shipping container with an on-board digital temperature data logger to provide a history of the temperature profile within the container during shipment. In previous work, several PCL formulations with temperatures of fusion ranging from approximately -14 to -20 C were prepared and evaluated. Both temperature of fusion and heat of fusion of the formulations were measured, and an optimal PCL formulation was selected. The PCL was frozen in plastic bags and tested for its temperature profile in a cooler using a digital temperature data logger. This testing showed that the PCL formulation can maintain freezer temperatures (< -7 to -20 C) for an extended period, such as the time for shipping samples by overnight courier. The results of the experiments described in this report provide significant information for use in developing an integrated freezer system that uses a PCL formulation to maintain freezer temperatures in coolers for shipping environmental samples to the laboratory. Experimental results show the importance of the type of cooler used in the system and that use of an insulating material within the cooler improves the performance of the freezer system. A new optimal PCL formulation for use in the system has been determined. The new formulation has been shown to maintain temperatures at < -7 to -20 C for 47 hours in an insulated cooler system containing soil samples. These results are very promising for developing the new technology.

  8. Calculation of Hamaker constants in non-aqueous fluid media

    SciTech Connect

    BELL,NELSON S.; DIMOS,DUANE B.

    2000-05-09

    Calculations of the Hamaker constants representing the van der Waals interactions between conductor, resistor and dielectric materials are performed using Lifshitz theory. The calculation of the parameters for the Ninham-Parsegian relationship for several non-aqueous liquids has been derived based on literature dielectric data. Discussion of the role of van der Waals forces in the dispersion of particles is given for understanding paste formulation. Experimental measurements of viscosity are presented to show the role of dispersant truncation of attractive van der Waals forces.

  9. Inorganic rechargeable non-aqueous cell

    SciTech Connect

    Bowden, William L.; Dey, Arabinda N.

    1985-05-07

    A totally inorganic non-aqueous rechargeable cell having an alkali or alkaline earth metal anode such as of lithium, a sulfur dioxide containing electrolyte and a discharging metal halide cathode, such as of CuCl.sub.2, CuBr.sub.2 and the like with said metal halide being substantially totally insoluble in SO.sub.2 and admixed with a conductive carbon material.

  10. Liquid-Phase Adsorption Fundamentals.

    ERIC Educational Resources Information Center

    Cooney, David O.

    1987-01-01

    Describes an experiment developed and used in the unit operations laboratory course at the University of Wyoming. Involves the liquid-phase adsorption of an organic compound from aqueous solution on activated carbon, and is relevant to adsorption processes in general. (TW)

  11. Liquid liquid phase transition in Stillinger Weber silicon

    NASA Astrophysics Data System (ADS)

    Beaucage, Philippe; Mousseau, Normand

    2005-04-01

    It was recently demonstrated that Stillinger-Weber silicon undergoes a liquid-liquid first-order phase transition deep into the supercooled region (Sastry and Angell 2003 Nat. Mater. 2 739). Here we study the effects of perturbations on this phase transition. We show that the order of the liquid-liquid transition changes with negative pressure. We also find that the liquid-liquid transition disappears when the three-body term of the potential is strengthened by as little as 5%. This implies that the details of the potential could affect strongly the nature and even the existence of the liquid-liquid phase.

  12. NON-AQUEOUS DISSOLUTION OF MASSIVE PLUTONIUM

    DOEpatents

    Reavis, J.G.; Leary, J.A.; Walsh, K.A.

    1959-05-12

    A method is presented for obtaining non-aqueous solutions or plutonium from massive forms of the metal. In the present invention massive plutonium is added to a salt melt consisting of 10 to 40 weight per cent of sodium chloride and the balance zinc chloride. The plutonium reacts at about 800 deg C with the zinc chloride to form a salt bath of plutonium trichloride, sodium chloride, and metallic zinc. The zinc is separated from the salt melt by forcing the molten mixture through a Pyrex filter.

  13. BEHAVIOR OF NON-AQUEOUS PHASE LIQUIDS IN FRACTURED POROUS MEDIA UNDER TWO-PHASE FLOW CONDITIONS. (R825689C080)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  14. Liquid-phase chromatography detector

    DOEpatents

    Voigtman, Edward G.; Winefordner, James D.; Jurgensen, Arthur R.

    1983-01-01

    A liquid-phase chromatography detector comprising a flow cell having an inlet tubular conduit for receiving a liquid chromatographic effluent and discharging it as a flowing columnar stream onto a vertically adjustable receiving surface spaced apart from and located vertically below and in close proximity to the discharge end of the tubular conduit; a receiver adapted to receive liquid overflowing from the receiving surface; an exit conduit for continuously removing liquid from the receiver; a light source for focussing fluorescence-producing light pulses on the flowing columnar stream as it passes from the outlet of the conduit to the receiving surface and a fluorescence detector to detect the produced fluorescence; a source of light pulse for producing acoustic waves in the columnar stream as it passes from the conduit outlet to the receiving surface; and a piezoelectric transducer adapted to detect those waves; and a source of bias voltage applied to the inlet tubular conduit and adapted to produce ionization of the liquid flowing through the flow cell so as to produce photocurrents therein and an electrical system to detect and record the photocurrents. This system is useful in separating and detecting individual chemical compounds from mixtures thereof.

  15. Liquid-phase chromatography detector

    DOEpatents

    Voigtman, E.G.; Winefordner, J.D.; Jurgensen, A.R.

    1983-11-08

    A liquid-phase chromatography detector comprises a flow cell having an inlet tubular conduit for receiving a liquid chromatographic effluent and discharging it as a flowing columnar stream onto a vertically adjustable receiving surface spaced apart from and located vertically below and in close proximity to the discharge end of the tubular conduit; a receiver adapted to receive liquid overflowing from the receiving surface; an exit conduit for continuously removing liquid from the receiver; a light source for focusing fluorescence-producing light pulses on the flowing columnar stream as it passes from the outlet of the conduit to the receiving surface and a fluorescence detector to detect the produced fluorescence; a source of light pulse for producing acoustic waves in the columnar stream as it passes from the conduit outlet to the receiving surface; and a piezoelectric transducer adapted to detect those waves; and a source of bias voltage applied to the inlet tubular conduit and adapted to produce ionization of the liquid flowing through the flow cell so as to produce photocurrents therein and an electrical system to detect and record the photocurrents. This system is useful in separating and detecting individual chemical compounds from mixtures thereof. 5 figs.

  16. Models for a liquid-liquid phase transition

    NASA Astrophysics Data System (ADS)

    Buldyrev, S. V.; Franzese, G.; Giovambattista, N.; Malescio, G.; Sadr-Lahijany, M. R.; Scala, A.; Skibinsky, A.; Stanley, H. E.

    2002-02-01

    We use molecular dynamics simulations to study two- and three-dimensional models with the isotropic double-step potential which in addition to the hard core has a repulsive soft core of larger radius. Our results indicate that the presence of two characteristic repulsive distances (hard core and soft core) is sufficient to explain liquid anomalies and a liquid-liquid phase transition, but these two phenomena may occur independently. Thus liquid-liquid transitions may exist in systems like liquid metals, regardless of the presence of the density anomaly. For 2D, we propose a model with a specific set of hard core and soft core parameters, that qualitatively reproduces the phase diagram and anomalies of liquid water. We identify two solid phases: a square crystal (high density phase), and a triangular crystal (low density phase) and discuss the relation between the anomalies of liquid and the polymorphism of the solid. Similarly to real water, our 2D system may have the second critical point in the metastable liquid phase beyond the freezing line. In 3D, we find several sets of parameters for which two fluid-fluid phase transition lines exist: the first line between gas and liquid and the second line between high-density liquid (HDL) and low-density liquid (LDL). In all cases, the LDL phase shows no density anomaly in 3D. We relate the absence of the density anomaly with the positive slope of the LDL-HDL phase transition line.

  17. Field test of high molecular weight alcohol flushing for subsurface nonaqueous phase liquid remediation

    NASA Astrophysics Data System (ADS)

    Falta, Ronald W.; Lee, Cindy M.; Brame, Scott E.; Roeder, Eberhard; Coates, John T.; Wright, Charles; Wood, A. Lynn; Enfield, Carl G.

    1999-07-01

    A pilot scale field test of non-aqueous phase liquid (NAPL) removal using high molecular weight alcohols was conducted at Operable Unit 1, Hill Air Force Base, Utah. Petroleum hydrocarbons and spent solvents were disposed of in chemical disposal pits at this site, and these materials are now present in the subsurface in the form of a light non-aqueous phase liquid (LNAPL). This LNAPL is a complex mixture of aromatic and aliphatic hydrocarbons, chlorinated solvents, and other compounds. The field experiment was performed in a 5 m by 3 m confined test cell, formed by driving interlocking sheet pile walls through the contaminated zone into an underlying clay. The test involved the injection and extraction of about four pore volumes (1 pore volume=7000 L) of a mixture of 80% tert-butanol and 15% n-hexanol. The contaminants were removed by a combination of NAPL mobilization and enhanced dissolution, and the results of postflood soil coring indicate better than 90% removal of the more soluble contaminants (trichloroethane, toluene, ethylbenzene, xylenes, trimethylbenzene, naphthalene) and 70-80% removal of less soluble compounds (decane and undecane). The results of preflood and postflood NAPL partitioning tracer tests show nearly 80% removal of the total NAPL content from the test cell. The field data suggest that a somewhat higher level of removal could be achieved with a longer alcohol injection.

  18. Novel Detection Method of Liquid-Liquid Phase Separation

    NASA Astrophysics Data System (ADS)

    Kato, Hitoshi; Katayanagi, Hideki; Koga, Yoshikata; Nishikawa, Keiko

    2004-12-01

    A novel method of determining a liquid-liquid phase boundary was developed. This method is based on our discovery that a nascent low-density phase is attracted to the center of a Rankine vortex at the onset of phase separation. Thus a liquid-liquid phase boundary is detected easily, rapidly, and accurately. The phase diagrams of the ternary systems NaCl-H2O-1-propanol and NaCl-H2O-1-butanol were obtained by this method. The results matched well with literature values.

  19. Mixed Stationary Liquid Phases for Gas-Liquid Chromatography.

    ERIC Educational Resources Information Center

    Koury, Albert M.; Parcher, Jon F.

    1979-01-01

    Describes a laboratory technique for use in an undergraduate instrumental analysis course that, using the interpretation of window diagrams, prepares a mixed liquid phase column for gas-liquid chromatography. A detailed procedure is provided. (BT)

  20. Spontaneous liquid-liquid phase separation of water.

    PubMed

    Yagasaki, Takuma; Matsumoto, Masakazu; Tanaka, Hideki

    2014-02-01

    We report a molecular dynamics simulation demonstrating a fast spontaneous liquid-liquid phase separation of water and a subsequent slow crystallization to ice. It is found that supercooled water separates rapidly into low- and high-density domains so as to reduce the surface energy in the rectangular simulation cell at certain thermodynamic states. The liquid-liquid phase separation, which is about two orders of magnitude faster than the crystallization, suggests a possibility to observe this phenomenon experimentally. PMID:25353404

  1. Liquid Phase Miscibility Gap Materials

    NASA Technical Reports Server (NTRS)

    Gelles, S. H.; Markworth, A. J.

    1985-01-01

    The manner in which the microstructural features of liquid-phase miscibility gap alloys develop was determined. This will allow control of the microstructures and the resultant properties of these alloys. The long-duration low gravity afforded by the shuttle will allow experiments supporting this research to be conducted with minimal interference from buoyancy effects and gravitationally driven convection currents. Ground base studies were conducted on Al-In, Cu-Pb, and Te-Tl alloys to determine the effect of cooling rate, composition, and interfacial energies on the phase separation and solidification processes that influence the development of microstructure in these alloys. Isothermal and directional cooling experiments and simulations are conducted. The ground based activities are used as a technological base from which flight experiments formulated and to which these flight experiments are compared.

  2. Transient liquid phase ceramic bonding

    DOEpatents

    Glaeser, Andreas M.

    1994-01-01

    Ceramics are joined to themselves or to metals using a transient liquid phase method employing three layers, one of which is a refractory metal, ceramic or alloy. The refractory layer is placed between two metal layers, each of which has a lower melting point than the refractory layer. The three layers are pressed between the two articles to be bonded to form an assembly. The assembly is heated to a bonding temperature at which the refractory layer remains solid, but the two metal layers melt to form a liquid. The refractory layer reacts with the surrounding liquid and a single solid bonding layer is eventually formed. The layers may be designed to react completely with each other and form refractory intermetallic bonding layers. Impurities incorporated into the refractory metal may react with the metal layers to form refractory compounds. Another method for joining ceramic articles employs a ceramic interlayer sandwiched between two metal layers. In alternative embodiments, the metal layers may include sublayers. A method is also provided for joining two ceramic articles using a single interlayer. An alternate bonding method provides a refractory-metal oxide interlayer placed adjacent to a strong oxide former. Aluminum or aluminum alloys are joined together using metal interlayers.

  3. Non-aqueous metathesis as a general approach to prepare nanodispersed materials: Case study of scheelites

    SciTech Connect

    Afanasiev, Pavel

    2015-09-15

    A general approach to the preparation of inorganic nanoparticles is proposed, using metathesis of precursor salts in non-aqueous liquids. Nanoparticles of scheelites AMO{sub 4} (A=Ba, Sr, Ca; M=Mo, W), were obtained with a quantitative yield. Precipitations in formamide, N-methylformamide, propylene carbonate, DMSO and polyols often provide narrow particle size distributions. Advantageous morphology was explained by strong ionic association in non-aqueous solvents, leading to slow nucleation and negligible Ostwald ripening. Mean particle size below 10 nm and high specific surface areas were obtained for several Ca(Sr)Mo(W)O{sub 4} materials, making them promising for applications as adsorbents or catalysts. Zeta-potential of scheelites in aqueous suspensions showed negative values in a wide range of pH. Systematic study of optical properties demonstrated variation of optical gap in the sequences W>Mo and Ba>Sr>Ca. The observed trends were reproduced by DFT calculations. No quantum confinement effect was observed for small particles, though the surface states induce low-energy features in the optical spectra. - Graphical abstract: Scheelites AMO{sub 4} (A=Ca, Sr, Ba; M=Mo, W) were prepared in various non-aqueous liquids with high specific surface areas and narrow size distributions. The optical gap of scheelites changes in the series Canon-aqueous liquids. • Narrow size distributions explained by ionic association in non-aqueous media. • Nanoparticles of less than 10 nm size and highest ever specific surface areas were obtained. • Optical gap of scheelites changes in the series Ca

  4. Non-aqueous cleaning solvent substitution

    NASA Technical Reports Server (NTRS)

    Meier, Gerald J.

    1994-01-01

    A variety of environmental, safety, and health concerns exist over use of chlorinated and fluorinated cleaning solvents. Sandia National Laboratories, Lawrence Livermore National Laboratories, and the Kansas City Division of AlliedSignal have combined efforts to focus on finding alternative cleaning solvents and processes which are effective, environmentally safe, and compliant with local, state, and federal regulations. An alternative solvent has been identified, qualified, and implemented into production of complex electronic assemblies, where aqueous and semi-aqueous cleaning processes are not allowed. Extensive compatibility studies were performed with components, piece-parts, and materials. Electrical testing and accelerated aging were used to screen for detrimental, long-term effects. A terpene, d-limonene, was selected as the solvent of choice, and it was found to be compatible with the components and materials tested. A brief history of the overall project will be presented, along with representative cleaning efficiency results, compatibility results, and residual solvent data. The electronics industry is constantly searching for proven methods and environmentally-safe materials to use in manufacturing processes. The information in this presentation will provide another option to consider on future projects for applications requiring high levels of quality, reliability, and cleanliness from non-aqueous cleaning processes.

  5. Non-aqueous cleaning solvent substitution

    SciTech Connect

    Meier, G.J.

    1994-01-01

    A variety of environmental, safety, and health concerns exist over use of chlorinated and fluorinated cleaning solvents. Sandia National Laboratories, Lawrence Livermore National Laboratories, and the Kansas City Division of Allied Signal have combined efforts to focus on finding alternative cleaning solvents and processes which are effective, environmentally safe, and compliant with local, state, and federal regulations. An alternative solvent has been identified, qualified, and implemented into production of complex electronic assemblies, where aqueous and semi-aqueous cleaning processes are not allowed. Extensive compatibility studies were performed with components, piece-parts, and materials. Electrical testing and accelerated aging were used to screen for detrimental, long-term effects. A terpene, d-limonene, has been selected as the solvent of choice, and has been found to be compatible with the components and materials tested. A brief history of the overall project will be presented, along with representative cleaning efficiency results, compatibility results, and residual solvent data. The electronics industry is constantly searching for proven methods and environmentally safe materials to use in manufacturing processes. The information in this presentation will provide another option to consider on future projects for applications requiring high levels of quality, reliability, and cleanliness from non-aqueous cleaning processes.

  6. Improved physical stability and injectability of non-aqueous in situ PLGA microparticle forming emulsions.

    PubMed

    Voigt, M; Koerber, M; Bodmeier, R

    2012-09-15

    The goal of this study was to obtain physically stable non-aqueous in situ forming microparticle (ISM) emulsions capable of forming biodegradable microparticles upon injection. ISM emulsions consist of a biocompatible organic PLGA solution dispersed in a continuous oil phase prepared in a two-syringe/connector system prior to administration. A variety of parenteral approved excipients were tested for a stability-enhancing effect and possible stabilization mechanisms evaluated. Glycerol monostearate (GMS) showed superior stabilizing potential prolonging the emulsion stability from a few minutes to more than 12h. Flow behavior analysis, differential scanning calorimetry, polarized light- and Cryo-electron microscopy revealed, that the stabilization was caused by an immediate, more than 5-fold viscosity increase in the continuous phase after emulsification and by a stabilized interface through a liquid crystalline GMS layer around the polymer solution droplets. Despite the viscosity increase the injectability of the stabilized ISM emulsion was improved by about 30% compared to the corresponding highly viscous PLGA solution (in situ implant) due to a pronounced shear thinning of the GMS containing oil phase. The injectability improvement allows a faster administration or enables the use of thinner needles and hence reduced patient discomfort. PMID:22677417

  7. Liquid phase sintering of silicon carbide

    DOEpatents

    Cutler, R.A.; Virkar, A.V.; Hurford, A.C.

    1989-05-09

    Liquid phase sintering is used to densify silicon carbide based ceramics using a compound comprising a rare earth oxide and aluminum oxide to form liquids at temperatures in excess of 1,600 C. The resulting sintered ceramic body has a density greater than 95% of its theoretical density and hardness in excess of 23 GPa. Boron and carbon are not needed to promote densification and silicon carbide powder with an average particle size of greater than one micron can be densified via the liquid phase process. The sintered ceramic bodies made by the present invention are fine grained and have secondary phases resulting from the liquid phase. 4 figs.

  8. Liquid phase sintering of silicon carbide

    DOEpatents

    Cutler, Raymond A.; Virkar, Anil V.; Hurford, Andrew C.

    1989-01-01

    Liquid phase sintering is used to densify silicon carbide based ceramics using a compound comprising a rare earth oxide and aluminum oxide to form liquids at temperatures in excess of 1600.degree. C. The resulting sintered ceramic body has a density greater than 95% of its theoretical density and hardness in excess of 23 GPa. Boron and carbon are not needed to promote densification and silicon carbide powder with an average particle size of greater than one micron can be densified via the liquid phase process. The sintered ceramic bodies made by the present invention are fine grained and have secondary phases resulting from the liquid phase.

  9. Liquid-phase combinatorial synthesis.

    PubMed Central

    Han, H; Wolfe, M M; Brenner, S; Janda, K D

    1995-01-01

    A concept termed liquid-phase combinatorial synthesis (LPCS) is described. The central feature of this methodology is that it combines the advantages that classic organic synthesis in solution offers with those that solid-phase synthesis can provide, through the application of a linear homogeneous polymer. To validate this concept two libraries were prepared, one of peptide and the second of nonpeptide origin. The peptide-based library was synthesized by a recursive deconvolution strategy [Erb, E., Janda, K. D. & Brenner, S. (1994) Proc. Natl. Acad. Sci. USA 91, 11422-11426] and several ligands were found within this library to bind a monoclonal antibody elicited against beta-endorphin. The non-peptide molecules synthesized were arylsulfonamides, a class of compounds of known clinical bactericidal efficacy. The results indicate that the reaction scope of LPCS should be general, and its value to multiple, high-throughput screening assays could be of particular merit, since multimilligram quantities of each library member can readily be attained. PMID:7541541

  10. Modeling liquid-liquid phase transitions and quasicrystal formation

    NASA Astrophysics Data System (ADS)

    Skibinsky, Anna

    In this thesis, studies which concern two different subjects related to phase transitions in fluids and crystalline solids are presented. Condensed matter formation, structure, and phase transitions are modeled using molecular dynamics simulations of simple discontinuous potentials with attractive and repulsive interactions. Novel phase diagrams are proposed for quasicrystals, crystals, and liquids. In the first part of the thesis, the formation of a quasicrystal in a two dimensional monodisperse system is investigated using molecular dynamics simulations of hard sphere particles interacting via a two-dimensional square-well potential. It is found that for certain values of the square-well parameters more than one stable crystalline phase can form. By quenching the liquid phase at a very low temperature, an amorphous phase is obtained. When this the amorphous phase is heated, a quasicrystalline structure with five-fold symmetry forms. From estimations of the Helmholtz potentials of the stable crystalline phases and of the quasicrystal, it is concluded that within a specific temperature range, the observed quasicrystal phase can be the stable phase. The second part of the thesis concerns a study of the liquid-liquid phase transition for a single-component system in three dimensions, interacting via an isotropic potential with a repulsive soft-core shoulder at short distance and an attractive well at an intermediate distance. The potential is similar to potentials used to describe such liquid systems as colloids, protein solutions, or liquid metals. It is shown that the phase diagram for such a potential can have two lines of first-order fluid-fluid phase transitions: one separating a gas and a low-density liquid (LDL), and another between the LDL and a high-density liquid (HDL). Both phase transition lines end in a critical point, a gas-LDL critical point and, depending on the potential parameters, either a gas-HDL critical point or a LDL-HDL critical point. A

  11. Operation with three liquid phases in a staged liquid-liquid contactor

    SciTech Connect

    Leonard, R.A.; Ziegler, A.A.; Wigeland, R.A.; Bane, R.W.; Steindler, M.J.

    1983-03-01

    Operation with three liquid phases was demonstrated in a staged liquid-liquid contactor. The possibility that three liquid phases could be handled in a liquid-liquid contactor normally used with two liquid phases was initially established using a laboratory batch test. Tht three liquid phases were obtained using a thorium flow sheet having high concentrations of both acid and thorium. To analyze the batch test, the concept of a dimensionless dispersion number for use with two liquid phases was extended so that it could be applied to three liquid phases. Based on the batch tests, continuous flow tests were run in a staged liquid-liquid contactor used for solvent extraction. A critical factor in the success of these tests was determining the position of the liquid-liquid interface in the contactor. Thus, a contactor was used which allows the position of the liquid-liquid interface to be adjusted. Actual three-phase operation was demonstrated using a 4-cm annular centrifugal contactor, albeit with a somewhat greater (3 to 4 vol. %) aqueous-phase contamination of the organic exit stream than normal (< 1 vol. %).

  12. Non-aqueous electrolytes for lithium-air batteries

    DOEpatents

    Amine, Khalil; Chen, Zonghai; Zhang, Zhengcheng

    2016-06-07

    A lithium-air cell includes a negative electrode; an air positive electrode; and a non-aqueous electrolyte which includes an anion receptor that may be represented by one or more of the formulas. ##STR00001##

  13. Advances in Non-Aqueous Chemistry

    ERIC Educational Resources Information Center

    Holliday, A. K.; Nicholls, D.

    1974-01-01

    A discussion concerning the choice of solvents for a chemical reaction is followed by an examination of the advantages of using liquid ammonia, oxide solvents, and molten salts as alternatives to water as a solvent. (DT)

  14. Randomized Grain Boundary Liquid Crystal Phase

    NASA Astrophysics Data System (ADS)

    Chen, D.; Wang, H.; Li, M.; Glaser, M.; Maclennan, J.; Clark, N.

    2012-02-01

    The formation of macroscopic, chiral domains, in the B4 and dark conglomerate phases, for example, is a feature of bent-core liquid crystals resulting from the interplay of chirality, molecular bend and molecular tilt. We report a new, chiral phase observed in a hockey stick-like liquid crystal molecule. This phase appears below a smectic A phase and cools to a crystal phase. TEM images of the free surface of the chiral phase show hundreds of randomly oriented smectic blocks several hundred nanometers in size, similar to those seen in the twist grain boundary (TGB) phase. However, in contrast to the TGB phase, these blocks are randomly oriented. The characteristic defects in this phase are revealed by freeze-fracture TEM images. We will show how these defects mediate the randomized orientation and discuss the intrinsic mechanism driving the formation of this phase. This work is supported by NSF MRSEC Grant DMR0820579 and NSF Grant DMR0606528.

  15. Phase behavior of ionic liquid crystals

    NASA Astrophysics Data System (ADS)

    Kondrat, S.; Bier, M.; Harnau, L.

    2010-05-01

    Bulk properties of ionic liquid crystals are investigated using density functional theory. The liquid crystal molecules are represented by ellipsoidal particles with charges located in their center or at their tails. Attractive interactions are taken into account in terms of the Gay-Berne pair potential. Rich phase diagrams involving vapor, isotropic and nematic liquid, as well as smectic phases are found. The dependence of the phase behavior on various parameters such as the length of the particles and the location of charges on the particles is studied.

  16. Generic mechanism for generating a liquid-liquid phase transition

    NASA Astrophysics Data System (ADS)

    Franzese, Giancarlo; Malescio, Gianpietro; Skibinsky, Anna; Buldyrev, Sergey V.; Stanley, H. Eugene

    2001-02-01

    Recent experimental results indicate that phosphorus-a single-component system-can have a high-density liquid (HDL) and a low-density liquid (LDL) phase. A first-order transition between two liquids of different densities is consistent with experimental data for a variety of materials, including single-component systems such as water, silica and carbon. Molecular dynamics simulations of very specific models for supercooled water, liquid carbon and supercooled silica predict a LDL-HDL critical point, but a coherent and general interpretation of the LDL-HDL transition is lacking. Here we show that the presence of a LDL and a HDL can be directly related to an interaction potential with an attractive part and two characteristic short-range repulsive distances. This kind of interaction is common to other single-component materials in the liquid state (in particular, liquid metals), and such potentials are often used to describe systems that exhibit a density anomaly. However, our results show that the LDL and HDL phases can occur in systems with no density anomaly. Our results therefore present an experimental challenge to uncover a liquid-liquid transition in systems like liquid metals, regardless of the presence of a density anomaly.

  17. Ion solvation in aqueous and non-aqueous solvents

    NASA Astrophysics Data System (ADS)

    Arslanargin, Ayse

    The thermodynamics of ion solvation is studied in both water and some organic solvents using computational and theoretical techniques. Free energy partitioning analysis is employed to explore the driving forces for ions interacting with the water liquid/vapor interface using optimized point charge models for the Na+ and I- ions and the extended simple point charge water model. The absolute hydration free energy is partitioned into cavity formation, attractive van der Waals, local electrostatic, and far-field electrostatic contributions. The bulk hydration free energy of the ions is computed first, followed by the free energy to insert the ions at the center of a water slab. Shifts of the ion free energies occur in the slab geometry are consistent with the extended simple point charge water model surface potential of the water liquid/vapor interface. Then the free energy profiles are examined for ion passage from the slab center to the dividing surface. The profiles show that, for the large chaotropic I- ion, the relatively flat total free energy profile results from the near cancellation of several large contributions. On the other hand, the small Na+ ion is repelled from the liquid/vapor interface mainly by the far field electrostatic term. The far-field electrostatic part of the free energy, largely due to the water liquid/vapor interface potential, has an important effect on ion distributions near the surface in the classical model. However, that the individual forms of the local and far-field electrostatic contributions are expected to be model dependent when comparing classical and quantum results. Non-aqueous solvents such as ethylene carbonate, and propylene carbonate are widely used as liquid electrolytes in electrochemical energy storage systems. The electrolyte structure affects the efficiency of the ion transport, and understanding the solvent structure is essential for battery performance enhancements. Free energy and enthalpy of solvation calculations

  18. Phase changes in liquid face seals

    NASA Technical Reports Server (NTRS)

    Hughes, W. F.

    1980-01-01

    Computer program predicts boiling (phase change) in liquid face seals. Program determines if and when boiling occurs, and calculates location of boiling interface, pressure and temperature profiles, and load.

  19. Correlation of three-liquid-phase equilibria involving ionic liquids.

    PubMed

    Rodríguez-Escontrela, I; Arce, A; Soto, A; Marcilla, A; Olaya, M M; Reyes-Labarta, J A

    2016-08-01

    The difficulty in achieving a good thermodynamic description of phase equilibria is finding a model that can be extended to a large variety of chemical families and conditions. This problem worsens in the case of systems containing more than two phases or involving complex compounds such as ionic liquids. However, there are interesting applications that involve multiphasic systems, and the promising features of ionic liquids suggest that they will play an important role in many future processes. In this work, for the first time, the simultaneous correlation of liquid-liquid and liquid-liquid-liquid equilibrium data for ternary systems involving ionic liquids has been carried out. To that end, the phase diagram of the water + [P6 6 6 14][DCA] + hexane system has been determined at 298.15 K and 323.15 K and atmospheric pressure. The importance of this system lies in the possibility of using the surface active ionic liquid to improve surfactant enhanced oil recovery methods. With those and previous measurements, thirteen sets of equilibrium data for water + ionic liquid + oil ternary systems have been correlated. The isoactivity equilibrium condition, using the NRTL model, and some pivotal strategies are proposed to correlate these complex systems. Good agreement has been found between experimental and calculated data in all the regions (one triphasic and two biphasic) of the diagrams. The geometric aspects related to the Gibbs energy of mixing function obtained using the model, together with the minor common tangent plane equilibrium condition, are valuable tools to check the consistency of the obtained correlation results. PMID:27427420

  20. Vapor-liquid phase separator studies

    NASA Technical Reports Server (NTRS)

    Yuan, S. W. K.; Lee, J. M.; Kim, Y. I.; Hepler, W. A.; Frederking, T. H. K.

    1983-01-01

    Porous plugs serve as both entropy rejection devices and phase separation components separating the vapor phase on the downstream side from liquid Helium 2 upstream. The liquid upstream is the cryo-reservoir fluid needed for equipment cooling by means of Helium 2, i.e Helium-4 below its lambda temperature in near-saturated states. The topics outlined are characteristic lengths, transport equations and plug results.

  1. Effect of gravity on liquid phase sintering

    NASA Technical Reports Server (NTRS)

    Mookherji, T.; Mcanelly, W. B.; Mckannan, E. C.

    1974-01-01

    The unique conditions offered by the earth orbital environment in material processing involving both solid and liquid phases, such as liquid phase sintering, were studied. An experimental development program involving both test and theoretical work was initiated. Experimental work using material combinations selected such that maximum information about the effect of gravity can be derived has been conducted. Wetting of the solid phase by the liquid during sintering is an important phenomenon in liquid phase sintering, and gravity has influence on both capillary phenomenon and density segregation; hence, material combinations were selected such that these two effects can be suitably studies. The experimental work is meant to form the basis for similar comparative work done under low-g conditions. The part of the model dealing with the capillary phenomenon, as related to liquid phase sintering and the effect of gravity on it, suggest that gravity will have negligible effect on the Bond number and that the cohesive force is dependent on both the amount of liquid phase and the angle of contact.

  2. Liquid-Liquid Phase Transition in Nanoconfined Silicon Carbide.

    PubMed

    Wu, Weikang; Zhang, Leining; Liu, Sida; Ren, Hongru; Zhou, Xuyan; Li, Hui

    2016-03-01

    We report theoretical evidence of a liquid-liquid phase transition (LLPT) in liquid silicon carbide under nanoslit confinement. The LLPT is characterized by layering transitions induced by confinement and pressure, accompanying the rapid change in density. During the layering transition, the proportional distribution of tetracoordinated and pentacoordinated structures exhibits remarkable change. The tricoordinated structures lead to the microphase separation between silicon (with the dominant tricoordinated, tetracoordinated, and pentacoordinated structures) and carbon (with the dominant tricoordinated structures) in the layer close to the walls. A strong layer separation between silicon atoms and carbon atoms is induced by strong wall-liquid forces. Importantly, the pressure confinement phase diagram with negative slopes for LLPT lines indicates that, under high pressure, the LLPT is mainly confinement-induced, but under low pressure, it becomes dominantly pressure-induced. PMID:26859609

  3. Solid-liquid phase transition in argon

    NASA Technical Reports Server (NTRS)

    Tsang, T.; Tang, H. T.

    1978-01-01

    Starting from the Lennard-Jones interatomic potential, a modified cell theory has been used to describe the solid-liquid phase transition in argon. The cell-size variations may be evaluated by a self-consistent condition. With the inclusion of cell-size variations, the transition temperature, the solid and liquid densities, and the liquid-phase radial-distribution functions have been calculated. These ab initio results are in satisfactory agreement with molecular-dynamics calculations as well as experimental data on argon.

  4. Comment on "Spontaneous liquid-liquid phase separation of water".

    PubMed

    Limmer, David T; Chandler, David

    2015-01-01

    Yagasaki et al. [Phys. Rev. E 89, 020301 (2014)] present results from a molecular dynamics trajectory illustrating coarsening of ice, which they interpret as evidence of transient coexistence between two distinct supercooled phases of liquid water. We point out that neither two distinct liquids nor criticality are demonstrated in this simulation study. Instead, the illustrated trajectory is consistent with coarsening behaviors analyzed and predicted in earlier work by others. PMID:25679744

  5. Liquid-phase compositions from vapor-phase analyses

    SciTech Connect

    Davis, W. Jr. ); Cochran, H.D. )

    1990-02-01

    Arsenic normally is not considered to be a contaminant. However, because arsenic was found in many cylinders of UF{sub 6}, including in corrosion products, a study was performed of the distribution of the two arsenic fluorides, AsF{sub 3} and AsF{sub 5}, between liquid and vapor phases. The results of the study pertain to condensation or vaporization of liquid UF{sub 6}. This study includes use of various experimental data plus many extrapolations necessitated by the meagerness of the experimental data. The results of this study provide additional support for the vapor-liquid equilibrium model of J.M. Prausnitz and his coworkers as a means of describing the distribution of various impurities between vapor and liquid phases of UF{sub 6}. Thus, it is concluded that AsF{sub 3} will tend to concentrate in the liquid phase but that the concentration of AsF{sub 5} in the vapor phase will exceed its liquid-phase concentration by a factor of about 7.5, which is in agreement with experimental data. Because the weight of the liquid phase in a condensation operation may be in the range of thousands of times that of the vapor phase, most of any AsF{sub 5} will be in the liquid phase in spite of this separation factor of 7.5. It may also be concluded that any arsenic fluorides fed into a uranium isotope separation plant will either travel with other low-molecular-weight gases or react with materials present in the plant. 25 refs., 3 figs., 6 tabs.

  6. Coexisting Liquid Phases Underlie Nucleolar Subcompartments.

    PubMed

    Feric, Marina; Vaidya, Nilesh; Harmon, Tyler S; Mitrea, Diana M; Zhu, Lian; Richardson, Tiffany M; Kriwacki, Richard W; Pappu, Rohit V; Brangwynne, Clifford P

    2016-06-16

    The nucleolus and other ribonucleoprotein (RNP) bodies are membrane-less organelles that appear to assemble through phase separation of their molecular components. However, many such RNP bodies contain internal subcompartments, and the mechanism of their formation remains unclear. Here, we combine in vivo and in vitro studies, together with computational modeling, to show that subcompartments within the nucleolus represent distinct, coexisting liquid phases. Consistent with their in vivo immiscibility, purified nucleolar proteins phase separate into droplets containing distinct non-coalescing phases that are remarkably similar to nucleoli in vivo. This layered droplet organization is caused by differences in the biophysical properties of the phases-particularly droplet surface tension-which arises from sequence-encoded features of their macromolecular components. These results suggest that phase separation can give rise to multilayered liquids that may facilitate sequential RNA processing reactions in a variety of RNP bodies. PAPERCLIP. PMID:27212236

  7. Existence of a liquid-liquid phase transition in methanol.

    PubMed

    Huš, Matej; Urbic, Tomaz

    2014-12-01

    A simple model is constructed to study the phase diagram and thermodynamic properties of methanol, which is described as a dimer of an apolar sphere mimicking the methyl group and a sphere with core-softened potential as the hydroxyl group. Performing classical Monte Carlo simulations, we obtained the phase diagram, showing a second critical point between two different liquid phases. Evaluating systems with a different number of particles, we extrapolate to infinite size in accordance with Ising universality class to obtain bulk values for critical temperature, pressure, and density. Strong evidence that the structure of the liquid changes upon transition from high- to low-density phase was provided. From the experimentally determined hydrogen bond strength and length in methanol and water, we propose where the second critical point of methanol should be. PMID:25615092

  8. Non-aqueous liquid compositions comprising ion exchange polymers

    DOEpatents

    Kim, Yu Seung; Lee, Kwan-Soo; Rockward, Tommy Q. T.

    2011-07-19

    Compositions, and methods of making thereof, comprising from about 1% to about 5% of a perfluorinated sulfonic acid ionomer or a hydrocarbon-based ionomer; and from about 95% to about 99% of a solvent, said solvent consisting essentially of a polyol; wherein said composition is substantially free of water and wherein said ionomer is uniformly dispersed in said solvent.

  9. Non-aqueous liquid compositions comprising ion exchange polymers

    DOEpatents

    Kim, Yu Seung; Lee, Kwan-Soo; Rockward, Tommy Q. T.

    2013-03-12

    Compositions, and methods of making thereof, comprising from about 1% to about 5% of a perfluorinated sulfonic acid ionomer or a hydrocarbon-based ionomer; and from about 95% to about 99% of a solvent, said solvent consisting essentially of a polyol; wherein said composition is substantially free of water and wherein said ionomer is uniformly dispersed in said solvent.

  10. Phase separation in transparent liquid-liquid miscibility gap systems

    NASA Technical Reports Server (NTRS)

    Gelles, S. H.; Bhat, B. N.; Laub, R. J.

    1979-01-01

    A program to be carried out on transparent liquid-phase miscibility gap materials was developed for the purpose of acquiring additional insight into the separation process occurring in these systems. The transparency feature allows the reaction to be viewed directly through light scattering and holographic methods.

  11. Liquid-Liquid phase transition in a single component system

    NASA Astrophysics Data System (ADS)

    Franzese, Giancarlo; Skibinsky, Anna; Buldyrev, Sergey; Stanley, H. Eugene

    2001-06-01

    Recent experimental results indicate that phosphorus, a single-component system, can have a high-density liquid (HDL) and a low-density liquid (LDL) phase. A first-order LDL-HDL transition line ending in a critical point is consistent with experimental data and Molecular Dynamics (MD) simulations for a variety of single-component systems such as water, silica and carbon, but a coherent and general interpretation of the LDL-HDL transition is lacking. By means of MD, we show that the LDL-HDL transition can be directly related to an interaction potential with an attractive part and with not one but `two' preferred short-range repulsive distances. This kind of interaction is common to other single-component materials in the liquid state, in particular liquid metals. For the fisrt time, we show that the LDL-HDL transition can occur in systems with no density anomaly, opening an experimental challenge to uncover a liquid-liquid transition in systems like liquid metals, regardless of the presence of the density anomaly.

  12. Phase separation kinetics in immiscible liquids

    NASA Technical Reports Server (NTRS)

    Sadoway, D. R.

    1986-01-01

    The kinetics of phase separation in the succinonitrile-water system are being investigated. Experiments involve initial physical mixing of the two immiscible liquids at a temperature above the consolute, decreasing the temperature into the miscibility gap, followed by imaging of the resultant microstructure as it evolves with time. Refractive index differences allow documentation of the changing microstructures by noninvasive optical techniques without the need to quench the liquid structures for analysis.

  13. Phase separation kinetics in immiscible liquids

    NASA Technical Reports Server (NTRS)

    Ng, Lee H.; Sadoway, Donald R.

    1987-01-01

    The kinetics of phase separation in the succinonitrile-water system are being investigated. Experiments involve initial physical mixing of the two immiscible liquids at a temperature above the consolute, decreasing the temperature into the miscibility gap, followed by iamging of the resultant microstructure as it evolves with time. Refractive index differences allow documentation of the changing microstructures by noninvasive optical techniques without the need to quench the liquid structures for analysis.

  14. Liquid crystal phase shifters for space applications

    NASA Astrophysics Data System (ADS)

    Woehrle, Christopher D.

    Space communication satellites have historically relied heavily on high gain gimbal dish antennas for performing communications. Reflector dish antennas lack flexibility in anti-jamming capabilities, and they tend to have a high risk associated to them given the need for mechanical mechanisms to beam steer. In recent years, a great amount of investment has been made into phased array antenna technologies. Phased arrays offer increased signal flexibility at reduced financial cost and in system risk. The problem with traditional phased arrays is the significant program cost and overall complexity added to the satellite by integrating antenna elements that require many dedicated components to properly perform adaptive beam steering. Several unique methods have been proposed to address the issues that plague traditional phase shifters slated for space applications. Proposed approaches range from complex mechanical switches (MEMS) and ferroelectric devices to more robust molecular changes. Nematic liquid crystals offer adaptive beam steering capabilities that traditional phased arrays have; however, with the added benefit of reduced system cost, complexity, and increased resilience to space environmental factors. The objective of the work presented is to investigate the feasibility of using nematic liquid crystals as a means of phase shifting individual phased array elements slated for space applications. Significant attention is paid to the survivability and performance of liquid crystal and associated materials in the space environment. Performance regarding thermal extremes and interactions with charged particles are the primary factors addressed.

  15. Polymorphism in glassy silicon: Inherited from liquid-liquid phase transition in supercooled liquid

    NASA Astrophysics Data System (ADS)

    Zhang, Shiliang; Wang, Li-Min; Zhang, Xinyu; Qi, Li; Zhang, Suhong; Ma, Mingzhen; Liu, Riping

    2015-02-01

    Combining molecular dynamics (MD) simulation and Voronoi polyhedral analyses, we discussed the microstructure evolution in liquid and glassy silicon during cooling by focusing on the fraction of various clusters. Liquid-liquid phase transition (LLPT) is detected in supercooled liquid silicon However, freezing the high-density liquid (HDL) to the glassy state is not achieved as the quenching rate goes up to 1014 K/s. The polyamorphism in glassy silicon is found to be mainly associated with low-density liquid (LDL).

  16. Polymorphism in glassy silicon: Inherited from liquid-liquid phase transition in supercooled liquid

    PubMed Central

    Zhang, Shiliang; Wang, Li-Min; Zhang, Xinyu; Qi, Li; Zhang, Suhong; Ma, Mingzhen; Liu, Riping

    2015-01-01

    Combining molecular dynamics (MD) simulation and Voronoi polyhedral analyses, we discussed the microstructure evolution in liquid and glassy silicon during cooling by focusing on the fraction of various clusters. Liquid-liquid phase transition (LLPT) is detected in supercooled liquid silicon However, freezing the high-density liquid (HDL) to the glassy state is not achieved as the quenching rate goes up to 1014 K/s. The polyamorphism in glassy silicon is found to be mainly associated with low-density liquid (LDL). PMID:25716054

  17. Liquid phase sintered compacts in space

    NASA Technical Reports Server (NTRS)

    Mookherji, T. K.; Mcanelly, W. B.

    1974-01-01

    A model that will explain the effect of gravity on liquid phase sintering was developed. Wetting characteristics and density segregation which are the two important phenomena in liquid phase sintering are considered in the model development. Experiments were conducted on some selected material combinations to study the gravity effects on liquid phase sintering, and to verify the validity of the model. It is concluded that: (1) The surface tension forces acting on solid particles in a one-g environment are not appreciably different from those anticipated in a 0.00001g/g sub 0 (or lower) environment. (2) The capillary forces are dependent on the contact angle, the quantity of the liquid phase, and the distance between solid particles. (3) The pores (i.e., bubbles) do not appear to be driven to the surface by gravity-produced buoyancy forces. (4) The length of time to produce the same degree of settling in a low-gravity environment will be increased significantly. (5) A low gravity environment would appear to offer a unique means of satisfactorily infiltrating a larger and/or complex shaped compact.

  18. Vapor-liquid phase separator permeability results

    NASA Technical Reports Server (NTRS)

    Yuan, S. W. K.; Frederking, T. H. K.

    1981-01-01

    Continued studies are described in the area of vapor-liquid phase separator work with emphasis on permeabilities of porous sintered plugs (stainless steel, nominal pore size 2 micrometer). The temperature dependence of the permeability has been evaluated in classical fluid using He-4 gas at atmospheric pressure and in He-2 on the basis of a modified, thermosmotic permeability of the normal fluid.

  19. DENSE NONAQUEOUS PHASE LIQUIDS -- A WORKSHOP SUMMARY

    EPA Science Inventory

    site characterization, and, therefore, DNAPL remediation, can be expected. Dense nonaqueous phase liquids (DNAPLs) in the subsurface are long-term sources of ground-water contamination, and may persist for centuries before dissolving completely in adjacent ground water. In respo...

  20. Centrifugal Liquid/Gas Separator With Phase Detectors

    NASA Technical Reports Server (NTRS)

    Schneider, Steven J.

    1994-01-01

    Centrifugal liquid/gas separator that includes phase (liquid or gas) detectors helps ensure exclusiveness of each phase at its assigned outlet. Acoustic sensors in centrifugal liquid/gas separator measure speeds of sound in nominally pure liquid and nominally pure gas at liquid and gas outlets respectively. When speed of sound is that of pure liquid or gas, valve opens to let liquid or gas flow out.

  1. Gravitational Role in Liquid Phase Sintering

    NASA Technical Reports Server (NTRS)

    Upadhyaya, Anish; Iacocca, Ronald G.; German, Randall M.

    1998-01-01

    To comprehensively understand the gravitational effects on the evolution of both the microstructure and the macrostructure during liquid phase sintering, W-Ni-Fe alloys with W content varying from 35 to 98 wt.% were sintered in microgravity. Compositions that slump during ground-based sintering also distort when sintered under microgravity. In ground-based sintering, low solid content alloys distort with a typical elephant-foot profile, while in microgravity, the compacts tend to spheroidize. This study shows that microstructural segregation occurs in both ground-based as well as microgravity sintering. In ground-based experiments, because of the density difference between the solid and the liquid phase, the solid content increases from top to the bottom of the sample. In microgravity, the solid content increases from periphery to the center of the samples. This study also shows that the pores during microgravity sintering act as a stable phase and attain anomalous shapes.

  2. Solid drop based liquid-phase microextraction.

    PubMed

    Ganjali, Mohammad Reza; Sobhi, Hamid Reza; Farahani, Hadi; Norouzi, Parviz; Dinarvand, Rassoul; Kashtiaray, Amir

    2010-04-16

    Solid drop based liquid-phase microextraction (SDLPME) is a novel sample preparation technique possessing obvious advantages of simple operation with a high pre-concentration factor, low cost and low consumption of organic solvent. SDLPME coupled with gas chromatography (GC), high-performance liquid chromatography (HPLC), and atomic absorption spectrometry (AAS) has been widely applied to the analyses of a different variety of samples. The basic principles, parameters affecting the extraction efficiency, and the latest applications of SDLPME are reviewed in this article. PMID:19962710

  3. Anion receptor compounds for non-aqueous electrolytes

    DOEpatents

    Lee, Hung Sui; Yang, Xiao-Oing; McBreen, James

    2000-09-19

    A new family of aza-ether based compounds including linear, multi-branched and aza-crown ethers is provided. When added to non-aqueous battery electrolytes, the new family of aza-ether based compounds acts as neutral receptors to complex the anion moiety of the electrolyte salt thereby increasing the conductivity and the transference number of LI.sup.+ ion in alkali metal batteries.

  4. Organic sulfur biodesulfurization status and non-aqueous biocatalysis

    SciTech Connect

    Finnerty, W.R.

    1993-12-31

    The use of microorganisms for biodesulfurization bioprocessing has attracted attention as a potential precombustion technology for reduction of the organosulfur content of high-sulfur fossil fuels. Several microorganisms have been reported as capable of reducing the organosulfur content of sulfur-containing heterocycles as well as high sulfur petroleum and coal in aqueous media. Currently, two microbial oxidative mechanisms are classified as carbon-targeted and sulfur-targeted reactions. The former results in hydroxylated products and do not address the removal of the sulfur atom without significant losses in fuel value. Sulfur-targeted reactions result in the loss of organosulfur and incorporation of oxygen into the final product(s). An alternative approach to water-based biodesulfurization technologies is non-aqueous biocatalysis. Non-aqueous biodesulfurization systems have been developed that convert sulfur-containing heterocycles to aromatic hydrocarbons and hydrogen sulfide under a hydrogen atmosphere. The development of functional biocatalysts that selectively abstract organosulfur in organic media such as dimethylformamide, tetrahydrofuran, and carbon tetrachloride offer numerous advantages in the bioprocessing of high-sulfur fossil fuels. The potential to couple non-aqueous biocatalysis with chemical catalysis to perform chemoenzymatic transformations offers new opportunities for the performance- and cost-effective bioprocessing of fossil fuels.

  5. Liquid-phase compositions from vapor-phase analyses

    SciTech Connect

    Davis, W. Jr.; Cochran, H.D.; Leitnaker, J.M.

    1989-09-01

    In the safe handling and processing of uranium hexafluoride (UF{sub 6}), it is often desirable to calculate vapor composition and pressure from known liquid composition and temperature. Furthermore, the ability to use analyses of equilibrium vapor-phase samples to calculate liquid-phase compositions would be economically advantageous to the International Atomic Energy Agency (IAEA) in its international safeguards program and to uranium enrichment operators. The latter technique is projected to save the IAEA on the order of $1500 or more per sample. Either type of calculation could be performed with a multicomponent vapor-liquid equilibrium (VLE) model if this model were shown to apply to UF{sub 6} and its common impurities. This report is concerned with the distribution of four potential impurities in UF{sub 6} between liquid and vapor phases. The impurities are carbon dioxide, sulfur hexafluoride, chloryl fluoride, and Freon-114 (CClF{sub 2}CClF{sub 2}). There are no binary equilibrium data on the first three of these impurities; hence, the VLE calculations are based entirely on the thermodynamic properties of the pure components. There are two sets of binary equilibrium data for the system Freon-114-UF{sub 6} that are analyzed in terms of the model of Prausnitz et al. Calculations based on these data are compared with those based solely on the thermodynamic properties of pure Freon-114 and pure UF{sub 6}. 23 refs., 3 figs., 5 tabs.

  6. Nanoparticles for Nonaqueous-phase liquids (NAPLs) Remediation

    NASA Astrophysics Data System (ADS)

    Jiemvarangkul, Pijit

    Nanotechnology has gained attention in various fields of science and engineering for more than decades. Many nanotechnologies using nanosorbents, nanosensors, and nanoparticles have been developed, studied, and used to solve environmental problems. This dissertation contributes to the applications of two types of nanoparticles: 1) using zero valent iron nanoparticle technology (nZVI) for treatment of groundwater contaminated by chlorinated hydrocarbons and study effect of polyelectrolyte polymers on enhancing the mobility of nZVI in porous media and 2) testing a new type of nanoparticle, nano-scale calcium peroxide (CaO2) particles (nano-peroxide); particles have been synthesized and preliminarily tests on their chemical properties and oxidizing reactions with petroleum hydrocarbons investigated. Trichloroethylene (TCE) is one of the high toxic, dense, non-aqueous phase liquids (DNAPLs) and it is one of the major problems of groundwater contamination. The direct reaction of nano-scale zerovalent iron (nZVI) particles and TCE liquid phase batch experiments shows that nZVI has capability to remove pure phase TCE and there is the reduction reaction occurred with reaction byproduct. Mass balance of nZVI-TCE reaction demonstrates that 7--9 % TCE mass was trapped in 1 g of nZVI sludge indicating that absorption occurred during the removal process confirming the absorption of TCE into nZVI sludge. The reaction and absorption abilities of nZVI are depended upon its surface areas. Increasing amount of nZVI reduces the space of batch experiment systems, so TCE removal efficiency of nZVI is decreased. These experiments show the practicability of using nZVI to directly remove TCE from contaminated groundwater. The transport of nanoscale zero-valent iron (nZVI) particles stabilized by three polyelectrolytes: polyvinyl alcohol-co-vinyl acetate-co-itaconic acid (PV3A), poly(acrylic acid) (PAA) and soy proteins were examined. The study shows the increase in nZVI mobility by

  7. Vapor-liquid phase separator studies

    NASA Technical Reports Server (NTRS)

    Yuan, S. W. K.; Hepler, W. A.; Frederking, T. H. K.

    1985-01-01

    A study of porous plug use for vapor-liquid phase seperation in spaceborne cryogenic systems was conducted. The three main topics addressed were: (1) the usefulness of porous media in designs that call for variable areas and flow rates; (2) the possibility of prediction of main parameters of porous plugs for a given material; and (3) prediction of all parameters of the plug, including secondary parameters.

  8. Phase Behavior of Perturbed Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Kralj, S.; Kutnjak, Z.; Lahajnar, G.; Svetec, M.

    We study theoretically the combined effect of confinement and randomness on LC phase transitions in orientational (isotropic-nematic) and translational (nematic-smectic A) degrees of ordering. We focus to cases where these transitions are of (very) weakly 1st order. An adequate experimental realisation is, e.g., 8CB liquid crystal confined to a Controlled-Pore Glass matrix. Based on universal responses of "hard" and "soft" continuum fields to distortions we derive how different mechanisms influence qualitative and quantitative characteristics of phase transitions under consideration.

  9. Liquid-phase electroepitaxy - Dopant segregation

    NASA Technical Reports Server (NTRS)

    Lagowski, J.; Jastrzebski, L.; Gatos, H. C.

    1980-01-01

    A theoretical model is presented which accounts for the dopant segregation in liquid-phase electroepitaxy in terms of dopant transport in the liquid phase (by electromigration and diffusion), the growth velocity, and the Peltier effect at the substrate-solution interface. The contribution of dopant electromigration to the magnitude of the effective segregation coefficient is dominant in the absence of convection; the contribution of the Peltier effect becomes significant only in the presence of pronounced convection. Quantitative expressions which relate the segregation coefficient to the growth parameters also permit the determination of the diffusion constant and electromigration mobility of the dopant in the liquid phase. The model was found to be in good agreement with the measured segregation characteristics of Sn in the electroepitaxial growth of GaAs from Ga-As solutions. For Sn in Ga-As solution at 900 C the diffusion constant was found to be 4 x 10 to the -5 sq cm/s and the electromigration velocity (toward the substrate with a positive polarity 2 x 10 to the -5 cm/s current density of 10 A/sq cm.

  10. Phase Segregation at the Liquid-Air Interface Prior to Liquid-Liquid Equilibrium.

    PubMed

    Bermúdez-Salguero, Carolina; Gracia-Fadrique, Jesús

    2015-08-13

    Binary systems with partial miscibility segregate into two liquid phases when their overall composition lies within the interval defined by the saturation points; out of this interval, there is one single phase, either solvent-rich or solute-rich. In most systems, in the one-phase regions, surface tension decreases with increasing solute concentration due to solute adsorption at the liquid-air interface. Therefore, the solute concentration at the surface is higher than in the bulk, leading to the hypothesis that phase segregation starts at the liquid-air interface with the formation of two surface phases, before the liquid-liquid equilibrium. This phenomenon is called surface segregation and is a step toward understanding liquid segregation at a molecular level and detailing the constitution of fluid interfaces. Surface segregation of aqueous binary systems of alkyl acetates with partial miscibility was theoretically demonstrated by means of a thermodynamic stability test based on energy minimization. Experimentally, the coexistence of two surface regions was verified through Brewster's angle microscopy. The observations were further interpreted with the aid of molecular dynamics simulations, which show the diffusion of the acetates from the bulk toward the liquid-air interface, where acetates aggregate into acetate-rich domains. PMID:26189700

  11. Phenyl boron-based compounds as anion receptors for non-aqueous battery electrolytes

    DOEpatents

    Lee, Hung Sui; Yang, Xiao-Qing; McBreen, James; Sun, Xuehui

    2002-01-01

    Novel fluorinated boronate-based compounds which act as anion receptors in non-aqueous battery electrolytes are provided. When added to non-aqueous battery electrolytes, the fluorinated boronate-based compounds of the invention enhance ionic conductivity and cation transference number of non-aqueous electrolytes. The fluorinated boronate-based anion receptors include different fluorinated alkyl and aryl groups.

  12. Liquid-liquid and liquid-solid phase separation and flocculation for a charged colloidal dispersion.

    PubMed

    Lai, S K; Wu, K L

    2002-10-01

    We model the intercolloidal interaction by a hard-sphere Yukawa repulsion to which is added the long-range van der Waals attraction. In comparison with the Derjaguin-Landau-Verwey-Overbeek repulsion, the Yukawa repulsion explicitly incorporates the spatial correlations between colloids and small ions. As a result, the repulsive part can be expressed analytically and has a coupling strength depending on the colloidal volume fraction. By use of this two-body potential of mean force and in conjunction with a second-order thermodynamic perturbation theory, we construct the colloidal Helmholtz free energy and use it to calculate the thermodynamic quantities, pressure and chemical potential, needed in the determination of the liquid-liquid and liquid-solid phase diagrams. We examine, in an aqueous charged colloidal dispersion, the effects of the Hamaker constant and particle size on the conformation of a stable liquid-liquid phase transition calculated with respect to the liquid-solid coexistence phases. We find that there exists a threshold Hamaker constant or particle size whose value demarcates the stable liquid-liquid coexistence phases from their metastable counterparts. Applying the same technique and using the energetic criterion, we extend our calculations to study the flocculation phenomenon in aqueous charged colloids. Here, we pay due attention to determining the loci of a stability curve stipulated for a given temperature T0, and obtain the parametric phase diagram of the Hamaker constant vs the coupling strength or, at given surface potential, the particle size. By imposing T0 to be the critical temperature T(c), i.e., setting k(B)T0 (=k(B)T(c)) equal to a reasonable potential barrier, we arrive at the stability curve that marks the irreversible/reversible phase transition. The interesting result is that there occurs a minimum size for the colloidal particles below (above) which the colloidal dispersion is driven to an irreversible (reversible) phase

  13. Liquid-Liquid Phase Separation of Oil Bodies from Seeds.

    PubMed

    Nykiforuk, Cory L

    2016-01-01

    Fundamentally, oil bodies are discrete storage organelles found in oilseeds, comprising a hydrophobic triacylglycerol core surrounded by a half-unit phospholipid membrane and an outer shell of specialized proteins known as oleosins. Oil bodies possess a number of attributes that were exploited by SemBioSys Genetics to isolate highly enriched fractions of oil bodies through liquid-liquid phase separation for a number of commercial applications. The current chapter provides a general guide for the isolation of oil bodies from Arabidopsis and/or safflower seed, from which protocols can be refined for different oilseed sources. For SemBioSys Genetic's recombinant technology, therapeutic proteins were covalently attached to oleosins or fused in-frame with ligands which bound oil bodies, facilitating their recovery to high levels of purity during "upstream processing" of transformed seed. Core to this technology was oil body isolation consisting of simple manipulation including homogenization of seeds to free the oil bodies, followed by the removal of insoluble fractions, and phase separation to recover the oil bodies. During oil body enrichment (an increase in oil body content concomitant with removal of impurities), a number of options and tips are provided to aid researchers in the manipulation and monitoring of these robust organelles. PMID:26614290

  14. Measurement of mass-transfer rates for surfactant-enhanced solubilization of nonaqueous phase liquids

    SciTech Connect

    Mayer, A.S.; Zhong, L.; Pope, G.A.

    1999-09-01

    Surfactant-enhanced solubilization of residual, non-aqueous-phase liquid (NAPL) contaminants is an emerging, subsurface remediation technology. The potential for nonequilibrium conditions is investigated for surfactant-enhanced solubilization of a NAPL, trichlorethylene (TCE), in a model porous medium. The surfactant formulation consists of an anionic surfactant, sodium dihexyl sulfosuccinate, an alcohol, and an electrolyte in aqueous solution. Batch solubilization experiments are conducted to assess the significant of chemical rate limitations. Surfactant flood experiments are conducted in packed columns with residual TCE. Mass-transfer rate coefficients are determined as a function of aqueous-phase pore velocity, NAPL volumetric fraction, and surfactant concentration. A correlation for predicting mass-transfer rate coefficients as a function of system properties is developed. The mass-transfer rate coefficients and correlation are obtained by fitting a transport simulator to the column effluent concentration results. Significant differences are found between the correlation developed here and correlations developed for other NAPL--surfactant systems. The correlation predicts near-linear dependences of mass-transfer rates on the NAPL volumetric fraction and pore velocity. Using the Damkohler number, the degree of nonequilibrium behavior in surfactant-enhanced NAPL solubilization is analyzed for a range of conditions. Nonequilibrium conditions are found to be significant at relatively low NAPL volumetric fractions.

  15. Blue-phase liquid crystal droplets

    PubMed Central

    Martínez-González, José A.; Zhou, Ye; Rahimi, Mohammad; Bukusoglu, Emre; Abbott, Nicholas L.; de Pablo, Juan J.

    2015-01-01

    Blue phases of liquid crystals represent unique ordered states of matter in which arrays of defects are organized into striking patterns. Most studies of blue phases to date have focused on bulk properties. In this work, we present a systematic study of blue phases confined into spherical droplets. It is found that, in addition to the so-called blue phases I and II, several new morphologies arise under confinement, with a complexity that increases with the chirality of the medium and with a nature that can be altered by surface anchoring. Through a combination of simulations and experiments, it is also found that one can control the wavelength at which blue-phase droplets absorb light by manipulating either their size or the strength of the anchoring, thereby providing a liquid–state analog of nanoparticles, where dimensions are used to control absorbance or emission. The results presented in this work also suggest that there are conditions where confinement increases the range of stability of blue phases, thereby providing intriguing prospects for applications. PMID:26460039

  16. Non-aqueous metathesis as a general approach to prepare nanodispersed materials: Case study of scheelites

    NASA Astrophysics Data System (ADS)

    Afanasiev, Pavel

    2015-09-01

    A general approach to the preparation of inorganic nanoparticles is proposed, using metathesis of precursor salts in non-aqueous liquids. Nanoparticles of scheelites AMO4 (A=Ba, Sr, Ca; M=Mo, W), were obtained with a quantitative yield. Precipitations in formamide, N-methylformamide, propylene carbonate, DMSO and polyols often provide narrow particle size distributions. Advantageous morphology was explained by strong ionic association in non-aqueous solvents, leading to slow nucleation and negligible Ostwald ripening. Mean particle size below 10 nm and high specific surface areas were obtained for several Ca(Sr)Mo(W)O4 materials, making them promising for applications as adsorbents or catalysts. Zeta-potential of scheelites in aqueous suspensions showed negative values in a wide range of pH. Systematic study of optical properties demonstrated variation of optical gap in the sequences W>Mo and Ba>Sr>Ca. The observed trends were reproduced by DFT calculations. No quantum confinement effect was observed for small particles, though the surface states induce low-energy features in the optical spectra.

  17. Non-aqueous electrolytes for lithium ion batteries

    SciTech Connect

    Chen, Zonghai; Amine, Khalil

    2015-11-12

    The present invention is generally related to electrolytes containing anion receptor additives to enhance the power capability of lithium-ion batteries. The anion receptor of the present invention is a Lewis acid that can help to dissolve LiF in the passivation films of lithium-ion batteries. Accordingly, one aspect the invention provides electrolytes comprising a lithium salt; a polar aprotic solvent; and an anion receptor additive; and wherein the electrolyte solution is substantially non-aqueous. Further there are provided electrochemical devices employing the electrolyte and methods of making the electrolyte.

  18. Wide Angle Liquid Crystal Optical Phased Array

    NASA Technical Reports Server (NTRS)

    Wang, Xing-Hua; Wang, Bin; Bos, Philip J.; Anderson, James E.; Pouch, John J.; Miranda, Felix A.; McManamon, Paul F.

    2004-01-01

    Accurate modeling of a high resolution, liquid crystal (LC) based, optical phased array (OPA) is shown. The simulation shows excellent agreement with a test 2-D LC OPA. The modeling method is extendable to cases where the array element size is close to the wavelength of light. The fringing fields of such a device are first studied, and subsequently reduced. This results in a device that demonstrates plus or minus 7.4 degrees of continuous beam steering at a wavelength of 1550 nm, and a diffraction efficiency (DE) higher than 72%.

  19. Liquid Crystal Phases of Semiflexible Polymers

    NASA Astrophysics Data System (ADS)

    Mackay, Ian; Sullivan, Don

    2012-02-01

    Liquid crystal polymers exhibit orientational order (nematic phase) and position order (smectic phase). Previous work on semiflexible polymers using self consistent field theory studied the isotropic-nematic and nematic-smectic transition for homogenous and diblock copolymers. The nematic phase is stabilized by excluded-volume effects between wormlike cylindrical segments. The smectic phase is further stabilized by excluded-volume effects between terminal end segments. Because models of semiflexible polymers include orientational degrees of freedom, in addition to the usual positional degrees of freedom, they are computationally more demanding to study. Spectral decomposition applied to segment orientations has previously been used to make computation feasible. However this method does not converge well for strongly ordered states, which arise in many real systems. I describe a Crank-Nicolson finite difference method applied to the orientations which is expected to converge well for highly ordered systems. This method also exhibits better numerical stability and accuracy and may thus serve as a better foundation for further studies of highly ordered systems. I also describe a modification to the spectral method which can compute the tilted Smectic C phase.

  20. Liquid-liquid phase transitions and water-like anomalies in liquids

    NASA Astrophysics Data System (ADS)

    Lascaris, Erik

    In this thesis we employ computer simulations and statistical physics to understand the origin of liquid-liquid phase transitions and their relationship with anomalies typical of liquid water. Compared with other liquids, water has many anomalies. For example the density anomaly: when water is cooled below 4 °C the density decreases rather than increases. This and other anomalies have also been found to occur in a few other one-component liquids, sometimes in conjunction with the existence of a liquid-liquid phase transition (LLPT) between a low-density liquid (LDL) and a high-density liquid (HDL). Using simple models we explain how these anomalies arise from the presence of two competing length scales. As a specific example we investigate the cut ramp potential, where we show the importance of "competition" in this context, and how one length scale can sometimes be zero. When there is a clear energetic preference for either LDL or HDL for all pressures and temperatures, then there is insufficient competition between the two liquid structures and no anomalies occur. From the simple models it also follows that anomalies can occur without the presence of a LLPT and vice versa. It remains therefore unclear if water has a LLPT that ends in a liquid-liquid critical point (LLCP), a hypothesis that was first proposed based on simulations of the ST2 water model. We confirm the existence of a LLCP in this model using finite size scaling and the Challa-Landau-Binder parameter, and show that the LLPT is not a liquid-crystal transition, as has recently been suggested. Previous research has indicated the possible existence of a LLCP in liquid silica. We perform a detailed analysis of two different silica models (WAC and BKS) at temperatures much lower than was previously simulated. Within the accessible temperature range we find no LLCP in either model, although in the case of WAC potential it is closely approached. We compare our results with those obtained for other

  1. Trichloroethene Reduction within a Nonaqueous Phase Liquid using Zero Valent Iron

    NASA Astrophysics Data System (ADS)

    Berge, N. D.; Ramsburg, C. A.

    2008-12-01

    The application of reactive slurries or suspensions (usually of reactive zero valent iron particles) is being considered for treatment of dense non-aqueous phase liquid (DNAPL) source zones. Effective treatment of NAPL source zones with reactive particles requires delivery of particles within the vicinity of the NAPL. To date, iron-mediated remediation technologies rely on the use of aqueous-based particle suspensions. When utilizing these aqueous-based suspensions of reactive iron particles, contaminant transformation is dependent on dissolution of contaminants from the DNAPL prior to reaction. The reliance upon dissolution kinetics may introduce a rate limitation during treatment of DNAPL source zones with aqueous-based reactive slurries. Incorporation of the reactive particles into the NAPL (i.e., reduction occurring within the NAPL) may alleviate any dissolution limitation associated with aqueous-based reactive slurries. This exploratory research evaluated the feasibility of creating iron-mediated TCE reduction within a NAPL. Emphasis was placed on elucidating the role of water in the reductive dechlorination process when it occurs within a NAPL. Batch experiments were conducted in 125 mL reactors containing iron particles and NAPLs of various composition under an argon atmosphere. For these proof-of-concept experiments, NAPL mixtures were designed to ensure initial TCE concentration was constant. Results suggest that iron-mediated reactions within chlorinated ethene DNAPLs are feasible, though the viability of controlling both the iron content and chemistry of DNAPL located within the subsurface remains unknown.

  2. Dense Nonaqueous Phase Liquids at Former Manufactured Gas Plants: Challenges to Modeling and Remediation

    PubMed Central

    Birak, P.S.; Miller, C.T.

    2008-01-01

    The remediation of dense non-aqueous phase liquids (DNAPLs) in porous media continues to be one of the most challenging problems facing environmental scientists and engineers. Of all the environmentally relevant DNAPLs, tars in the subsurface at former manufactured gas plants (FMGP’s) pose one of the biggest challenges due to their complex chemical composition and tendency to alter wettability. To further our understanding of these complex materials, we consulted historic documentation to evaluate the impact of gas manufacturing on the composition and physicochemical nature of the resulting tars. In the recent literature, most work to date has been focused in a relatively narrow portion of the expected range of tar materials, which has yielded a bias toward samples of relatively low viscosity and density. In this work, we consider the dissolution and movement of tars in the subsurface, models used to predict these phenomena, and approaches used for remediation. We also explore the open issues and detail important gaps in our fundamental understanding of these extraordinarily complex systems that must be resolved to reach a mature level of understanding. PMID:19176266

  3. On liquid phases in cometary nuclei

    NASA Astrophysics Data System (ADS)

    Miles, Richard; Faillace, George A.

    2012-06-01

    In this paper we review the relevant literature and investigate conditions likely to lead to melting of H2O ice, methanol (CH3OH) ice, ethane (C2H6) ice and other volatile ices in cometary nuclei. On the basis of a heat balance model which takes account of volatiles loss, we predict the formation of occasional aqueous and hydrocarbon liquid phases in subsurface regions at heliocentric distances, rh of 1-3 AU, and 5-12 AU, respectively. Low triple-point temperatures and low vapour pressures of C2H6, C3H8, and some higher-order alkanes and alkenes, favour liquid phase formation in cometary bodies at high rh. Microporosity and the formation of a stabilization crust occluding the escape of volatiles facilitate liquid-phase formation. Characteristics of the near-surface which favour subsurface melting include; low effective surface emissivity (at low rh), high amorphous carbon content, average pore sizes of ˜10 μm or less, presence of solutes (e.g. CH3OH), mixtures of C2-C6 hydrocarbons (for melting at high rh), diurnal thermal cycling, and slow rotation rate. Applying the principles of soil mechanics, capillary forces are shown to initiate pre-melting phenomena and subsequent melting, which is expected to impart considerable strength of ˜104 Pa in partially saturated layers, reducing porosity and permeability, enhancing thermal conductivity and heat transfer. Diurnal thermal cycling is expected to have a marked effect on the composition and distribution of H2O ice in the near-surface leading to frost heave-type phenomena even where little if any true melting occurs. Where melting does take place, capillary suction in the wetted zone has the potential to enhance heat transfer via capillary wetting in a low-gravity environment, and to modify surface topography creating relatively smooth flat-bottomed features, which have a tendency to be located within small depressions. An important aspect of the "wetted layer" model is the prediction that diurnal melt-freeze cycles

  4. Liquid phase stability under an extreme temperature gradient.

    PubMed

    Liang, Zhi; Sasikumar, Kiran; Keblinski, Pawel

    2013-11-27

    Using nonequilibrium molecular dynamics simulations, we subject bulk liquid to a very high-temperature gradient and observe a stable liquid phase with a local temperature well above the boiling point. Also, under this high-temperature gradient, the vapor phase exhibits condensation into a liquid at a temperature higher than the saturation temperature, indicating that the observed liquid stability is not caused by nucleation barrier kinetics. We show that, assuming local thermal equilibrium, the phase change can be understood from the thermodynamic analysis. The observed elevation of the boiling point is associated with the interplay between the "bulk" driving force for the phase change and surface tension of the liquid-vapor interface that suppresses the transformation. This phenomenon is analogous to that observed for liquids in confined geometries. In our study, however, a low-temperature liquid, rather than a solid, confines the high-temperature liquid. PMID:24329454

  5. Liquid Phase Stability Under an Extreme Temperature Gradient

    NASA Astrophysics Data System (ADS)

    Liang, Zhi; Sasikumar, Kiran; Keblinski, Pawel

    2013-11-01

    Using nonequilibrium molecular dynamics simulations, we subject bulk liquid to a very high-temperature gradient and observe a stable liquid phase with a local temperature well above the boiling point. Also, under this high-temperature gradient, the vapor phase exhibits condensation into a liquid at a temperature higher than the saturation temperature, indicating that the observed liquid stability is not caused by nucleation barrier kinetics. We show that, assuming local thermal equilibrium, the phase change can be understood from the thermodynamic analysis. The observed elevation of the boiling point is associated with the interplay between the “bulk” driving force for the phase change and surface tension of the liquid-vapor interface that suppresses the transformation. This phenomenon is analogous to that observed for liquids in confined geometries. In our study, however, a low-temperature liquid, rather than a solid, confines the high-temperature liquid.

  6. Stable liquid crystalline phases of colloidally dispersed exfoliated layered niobates.

    PubMed

    Nakato, Teruyuki; Miyamoto, Nobuyoshi; Harada, Akiko

    2004-01-01

    Colloidally dispersed niobium oxide nanosheets obtained by exfoliation of layered niobates HNb(3)O(8) and HTiNbO(5) formed stable liquid crystalline phases; their liquid crystallinity was dependent on the niobate species exfoliated. PMID:14737341

  7. Preparation of silver nanoparticles by a non-aqueous sol-gel process.

    PubMed

    Petit, Christophe T G; Alsulaiman, Muath S A; Lan, Rong; Mann, Gregory; Tao, Shanwen

    2013-08-01

    Using a non-aqueous sol-gel process with a direct calcination step in air after prior drying, silver nanoparticles with average size distribution ranging from 20 to 100 nm were synthesised. Studies in reduced atmosphere were also performed with mixed results, both in phase and particle size, as the samples were found to be mixed with an amorphous phase. In oxidising atmosphere, the temperature and dwelling time were found to be critical factors with the former playing a larger role than the latter. Optimally nanoparticles of silver are best prepared by direct calcination in air of the precursor gel at 250 degrees C for 1 hour. Compared to silver particles prepared by microemulsions, the particle size is larger due to the thermal treatment, which causes a growth of the silver particles. PMID:23882777

  8. Quantum Liquid Crystal Phases in Strongly Correlated Fermionic Systems

    ERIC Educational Resources Information Center

    Sun, Kai

    2009-01-01

    This thesis is devoted to the investigation of the quantum liquid crystal phases in strongly correlated electronic systems. Such phases are characterized by their partially broken spatial symmetries and are observed in various strongly correlated systems as being summarized in Chapter 1. Although quantum liquid crystal phases often involve…

  9. Non-aqueous polypyrrole colloids: Synthesis and characterization

    SciTech Connect

    Armes, S.P.; Aldissi, Mahmoud

    1989-01-01

    The preparation of sterically-stabilized polypyrrole colloids via a dispersion polymerization route in non-aqueous media is described for the first time. Pyrrole polymerization was achieved using FeCl/sub 3/ as an oxidant/dopant in organic solvents such as methyl acetate, methyl formate and propyl formate. Macroscopic precipitation was prevented by the use of poly (vinyl acetate) as a polymeric surfactant. Other surfactants, used successfully in aqueous media, were incompatible and consequently resulted in precipitation of polypyrrole. Several techniques were used for characterization of the dispersions including transmission and scanning electron microscopies (TEM and SEM), thermogravimetric analysis (TGA), velocity charge analysis and visible absorption spectroscopy. TEM indicated a polydisperse spherical morphology with a particle diameter in the range 100-300 nm. The compressed pellet conductivity of the dried dispersion was 0.1 S/cm. These dispersions are often compared with aqueous bulk polypyrrole and aqueous dispersions. 11 refs., 3 figs., 1 tab.

  10. Electric cell with a non-aqueous electrolyte

    SciTech Connect

    Brec, R.; Dugast, A.; Le Mehaute, A.

    1982-01-05

    A secondary electric cell is described which includes: a non-aqueous electrolyte, a negative electrode whose active material includes at least one alkali metal in contact with the electrolyte, and a positive electrode whose active material is suitable for intercalating the active material of the negative electrode, wherein said positive electrode includes an active compound or solid solution whose general formula is Mxx, RyX3 where: M is an element chosen from lead and tin; R is an element chosen from bismuth and antimony; and X is an element chosen from sulphur and selenium, with X having a value lying between 0 and 1 (Inclusive), and Y having a value lying between 0 and 2 (Inclusive). Such cells may be used in watches or pacemakers.

  11. Electric cell with a non-aqueous electrolyte

    SciTech Connect

    Le Blanc-Soreau, A.; Le Mehaute, A.; Rouxel, J.

    1982-03-02

    An electric cell with a non-aqueous electrolyte. The cell includes a positive electrode whose active material is suitable for inserting the negative active material dynamically, a negative electrode whose active material includes at least one alkali metal, and an electrolyte, wherein said positive electrode includes at least one compound whose general formula is mx4rntp, where M represents an element chosen from among silicon, germanium, tin and lead, X represents sulphur, selenium or tellurium, R and T represent an element chosen from among copper, silver, manganese, iron, cobalt and nickel, N being greater than or equal to 0 and less than or equal to 4, P being greater than or equal to 0 and less than or equal to 2. The invention is used in connection with button type electric cells.

  12. The Renaissance of Non-Aqueous Uranium Chemistry.

    PubMed

    Liddle, Stephen T

    2015-07-20

    Prior to the year 2000, non-aqueous uranium chemistry mainly involved metallocene and classical alkyl, amide, or alkoxide compounds as well as established carbene, imido, and oxo derivatives. Since then, there has been a resurgence of the area, and dramatic developments of supporting ligands and multiply bonded ligand types, small-molecule activation, and magnetism have been reported. This Review 1) introduces the reader to some of the specialist theories of the area, 2) covers all-important starting materials, 3) surveys contemporary ligand classes installed at uranium, including alkyl, aryl, arene, carbene, amide, imide, nitride, alkoxide, aryloxide, and oxo compounds, 4) describes advances in the area of single-molecule magnetism, and 5) summarizes the coordination and activation of small molecules, including carbon monoxide, carbon dioxide, nitric oxide, dinitrogen, white phosphorus, and alkanes. PMID:26079536

  13. Surfactant mediated liquid phase exfoliation of graphene

    NASA Astrophysics Data System (ADS)

    Narayan, Rekha; Kim, Sang Ouk

    2015-10-01

    Commercialization of graphene based applications inevitably requires cost effective mass production. From the early days of research on graphene, direct liquid phase exfoliation (LPE) of graphite has been considered as the most promising strategy to produce high-quality mono or few-layer graphene sheets in solvent dispersion forms. Substantial success has been achieved thus far in the LPE of graphene employing numerous solvent systems and suitable surfactants. This invited review article principally showcase the recent research progress as well as shortcomings of surfactant assisted LPE of graphene. In particular, a comprehensive assessment of the quality and yield of the graphene sheets produced by different categories of the surfactants are summarized. Future direction of LPE methods is also proposed for the eventual success of commercial applications.

  14. Replication Experiments in Microgravity Liquid Phase Sintering

    NASA Astrophysics Data System (ADS)

    German, Randall M.; Johnson, John L.

    2016-05-01

    Although considerable experience exists with sintering on Earth, the behavior under reduced gravity conditions is poorly understood. This study analyzes replica microgravity liquid phase sintering data for seven tungsten alloys (35 to 88 wt pct tungsten) sintered for three hold times (1, 180, or 600 minutes) at 1773 K (1500 °C) using 0.002 pct of standard gravity. Equivalent sintering is performed on Earth using the same heating cycles. Microgravity sintering results in a lower density and more shape distortion. For Earth-based sintering, minimized distortion is associated with low liquid contents to avoid solid settling and slumping. Distortion in microgravity sintering involves viscous spreading of the component at points of contact with the containment crucible. Distortion in microgravity is minimized by short hold times; long hold times allow progressive component reshaping toward a spherical shape. Microgravity sintering also exhibits pore coalescence into large, stable voids that cause component swelling. The microgravity sintering results show good replication in terms of mass change and sintered density. Distortion is scattered but statistically similar between the replica microgravity runs. However, subtle factors, not typically of concern on Earth, emerge to influence microgravity sintering, such that ground experiments do not provide a basis to predict microgravity behavior.

  15. Two-phase liquid-liquid flows generated by impinging liquid jets

    NASA Astrophysics Data System (ADS)

    Tsaoulidis, Dimitrios; Li, Qi; Angeli, Panagiota

    2015-11-01

    Two-phase flows in intensified small-scale systems find increasing applications in (bio)chemical analysis and synthesis, fuel cells, polymerisation, and separation processes (solvent extraction). Current nuclear spent fuel reprocessing separation technologies have been developed many decades ago and have not taken account recent advances on process intensification which can drive down plant size and economics. In this work, intensified impinging jets will be developed to create dispersions by bringing the two liquid phases into contact through opposing small channels. A systematic set of experiments has been undertaken, to investigate the hydrodynamic characteristics, to develop predictive models, and enable comparisons with other contactors. Drop size distribution and mixing intensity will be investigated for liquid-liquid mixtures as a function of various parameters using high speed imaging and conductivity probes.

  16. ANALYSIS OF A GAS-PHASE PARTITIONING TRACER TEST CONDUCTED THROUGH FRACTURED MEDIA

    EPA Science Inventory

    The gas-phase partitioning tracer method was used to estimate non-aqueous phase liquid (NAPL), water, and air saturations in the vadose zone at a chlorinated-solvent contaminated field site in Tucson, AZ. The tracer test was conducted in a fractured clay system that is the confin...

  17. Protein Phase Behavior in Aqueous Solutions: Crystallization, Liquid-Liquid Phase Separation, Gels, and Aggregates

    PubMed Central

    Dumetz, André C.; Chockla, Aaron M.; Kaler, Eric W.; Lenhoff, Abraham M.

    2008-01-01

    The aggregates and gels commonly observed during protein crystallization have generally been considered disordered phases without further characterization. Here their physical nature is addressed by investigating protein salting-out in ammonium sulfate and sodium chloride for six proteins (ovalbumin, ribonuclease A, soybean trypsin inhibitor, lysozyme, and β-lactoglobulin A and B) at 4°C, 23°C, and 37°C. When interpreted within the framework of a theoretical phase diagram obtained for colloidal particles displaying short-range attractive interactions, the results show that the formation of aggregates can be interpreted theoretically in terms of a gas-liquid phase separation for aggregates that are amorphous or gel-like. A notable additional feature is the existence of a second aggregation line observed for both ovalbumin and ribonuclease A in ammonium sulfate, interpreted theoretically as the spinodal. Further investigation of ovalbumin and lysozyme reveals that the formation of aggregates can be interpreted, in light of theoretical results from mode-coupling theory, as a kinetically trapped state or a gel phase that occurs through the intermediate of a gas-liquid phase separation. Despite the limitations of simple theoretical models of short-range attractive interactions, such as their inability to reproduce the effect of temperature, they provide a framework useful to describe the main features of protein phase behavior. PMID:18160663

  18. Liquid plasmonics: manipulating surface plasmon polaritons via phase transitions.

    PubMed

    Vivekchand, S R C; Engel, Clifford J; Lubin, Steven M; Blaber, Martin G; Zhou, Wei; Suh, Jae Yong; Schatz, George C; Odom, Teri W

    2012-08-01

    This paper reports the manipulation of surface plasmon polaritons (SPPs) in a liquid plasmonic metal by changing its physical phase. Dynamic properties were controlled by solid-to-liquid phase transitions in 1D Ga gratings that were fabricated using a simple molding process. Solid and liquid phases were found to exhibit different plasmonic properties, where light coupled to SPPs more efficiently in the liquid phase. We exploited the supercooling characteristics of Ga to access plasmonic properties associated with the liquid phase over a wider temperature range (up to 30 °C below the melting point of bulk Ga). Ab initio density functional theory-molecular dynamic calculations showed that the broadening of the solid-state electronic band structure was responsible for the superior plasmonic properties of the liquid metal. PMID:22823536

  19. Computer simulations of liquid silica: Equation of state and liquid-liquid phase transition

    NASA Astrophysics Data System (ADS)

    Saika-Voivod, Ivan; Sciortino, Francesco; Poole, Peter H.

    2001-01-01

    We conduct extensive molecular dynamics computer simulations of two models for liquid silica [the model of Woodcock, Angell and Cheeseman, J. Phys. Chem. 65, 1565 (1976); and that of van Beest, Kramer, and van Santen, Phys. Rev. Lett. 64, 1955 (1990)] to determine their thermodynamic properties at low temperature T across a wide density range. We find for both models a wide range of states in which isochores of the potential energy U are a linear function of T3/5, as recently proposed for simple liquids [Rosenfeld and P. Tarazona, Mol. Phys. 95, 141 (1998)]. We exploit this behavior to fit an accurate equation of state to our thermodynamic data. Extrapolation of this equation of state to low T predicts the occurrence of a liquid-liquid phase transition for both models. We conduct simulations in the region of the predicted phase transition, and confirm its existence by direct observation of phase separating droplets of atoms with distinct local density and coordination environments.

  20. Defects and order in liquid crystal phases

    NASA Astrophysics Data System (ADS)

    Jain, Shilpa

    This thesis investigates the partial destruction of ordering in liquid crystalline systems due to the influence of defects and thermal fluctuations. The systems under consideration are hexagonal columnar crystals with crystalline order perpendicular to the columns, and two-dimensional smectics with order perpendicular to the layers. We first study the possibility of reentrant melting of a hexagonal columnar crystal of flexible charged polymers at high enough densities. The Lindemann criterion is employed in determining the melting point. Lattice fluctuations are calculated in the Debye model, and an analogy with the Abrikosov vortex lattice in superconductors is exploited in estimating both the elastic constants of the hexagonal lattice, and the appropriate Lindemann constant. We also discuss the unusual functional integral describing the statistical mechanics of a single polymer in an Einstein cage model using the path-integral formulation. A crossover as a function of an external field along the column axis is discussed as well. Next, we study defects in a columnar crystal in the form of vacancy/interstitial loops or strings of vacancies and interstitials bounded by column "heads" and "tails". These defect strings are oriented by the columnar lattice and can change size and shape by movement of the ends and forming kinks along the length. Hence an analysis in terms of directed living polymers is appropriate to study their size and shape distribution, volume fraction, etc. If the entropy of transverse fluctuations overcomes the string line tension in the crystalline phase, a string proliferation transition occurs, leading to a "supersolid" phase with infinitely long vacancy or interstitial strings. We estimate the wandering entropy and examine the behaviour in the transition regime. We also calculate numerically the line tension of various species of vacancies and interstitials in a triangular lattice for power-law potentials as well as for a modified Bessel

  1. Coal-Face Fracture With A Two-Phase Liquid

    NASA Technical Reports Server (NTRS)

    Collins, E. R., Jr.

    1985-01-01

    In new method for mining coal without explosive, two-phase liquid such as CO2 and water, injected at high pressure into deeper ends of holes drilled in coal face. Liquid permeates coal seam through existing microfractures; as liquid seeps back toward face, pressure eventually drops below critical value at which dissolved gas flashvaporizes, breaking up coal.

  2. Encapsulated ionic liquids (ENILs): from continuous to discrete liquid phase.

    PubMed

    Palomar, Jose; Lemus, Jesus; Alonso-Morales, Noelia; Bedia, Jorge; Gilarranz, Miguel A; Rodriguez, Juan J

    2012-10-14

    Encapsulated ionic liquid (ENIL) material was developed, consisting of ionic liquid (IL) introduced into carbon submicrocapsules. ENILs contain >85% w/w of IL but discretized in submicroscopic encapsulated drops, drastically increasing the surface contact area with respect to the neat fluid. ENIL materials were here tested for gas separation processes, obtaining a drastic increase in mass transfer rate. PMID:22935733

  3. Liquid-Liquid Phase Transition and Glass Transition in a Monoatomic Model System

    PubMed Central

    Xu, Limei; Buldyrev, Sergey V.; Giovambattista, Nicolas; Stanley, H. Eugene

    2010-01-01

    We review our recent study on the polyamorphism of the liquid and glass states in a monatomic system, a two-scale spherical-symmetric Jagla model with both attractive and repulsive interactions. This potential with a parametrization for which crystallization can be avoided and both the glass transition and the liquid-liquid phase transition are clearly separated, displays water-like anomalies as well as polyamorphism in both liquid and glassy states, providing a unique opportunity to study the interplay between the liquid-liquid phase transition and the glass transition. Our study on a simple model may be useful in understanding recent studies of polyamorphism in metallic glasses. PMID:21614201

  4. Liquid Crystals: The Phase of the Future.

    ERIC Educational Resources Information Center

    Ondris-Crawford, Renate; And Others

    1992-01-01

    Liquid crystal displays are currently utilized to convey information via graphic displays. Presents experiments and explanations that employ the concept of liquid crystals to learn concepts related to the various states of matter, electric and magnetic forces, refraction of light, and optics. Discusses applications of liquid crystal technology.…

  5. ANALYSIS OF A GAS-PHASE PARTITIONING TRACER TEST CONDUCTED IN AN UNSATURATED FRACTURED-CLAY FORMATION

    EPA Science Inventory

    The gas-phase partitioning tracer method was used to estimate non-aqueous phase liquid (NAPL), water, and air saturations in the vadose zone at a chlorinated-solvent contaminated field site in Tucson, AZ. The tracer test was conducted in a fractured-clay system that is the confin...

  6. Images reveal that atmospheric particles can undergo liquid-liquid phase separations.

    PubMed

    You, Yuan; Renbaum-Wolff, Lindsay; Carreras-Sospedra, Marc; Hanna, Sarah J; Hiranuma, Naruki; Kamal, Saeid; Smith, Mackenzie L; Zhang, Xiaolu; Weber, Rodney J; Shilling, John E; Dabdub, Donald; Martin, Scot T; Bertram, Allan K

    2012-08-14

    A large fraction of submicron atmospheric aerosol particles contains both organic material and inorganic salts. As the relative humidity cycles in the atmosphere and the water content of the particles correspondingly changes, these mixed particles can undergo a range of phase transitions, possibly including liquid-liquid phase separation. If liquid-liquid phase separation occurs, the gas-particle partitioning of atmospheric semivolatile organic compounds, the scattering and absorption of solar radiation, and the reactive uptake of gas species on atmospheric particles may be affected, with important implications for climate predictions. The actual occurrence of liquid-liquid phase separation within individual atmospheric particles has been considered uncertain, in large part because of the absence of observations for real-world samples. Here, using optical and fluorescence microscopy, we present images that show the coexistence of two noncrystalline phases for real-world samples collected on multiple days in Atlanta, GA as well as for laboratory-generated samples under simulated atmospheric conditions. These results reveal that atmospheric particles can undergo liquid-liquid phase separations. To explore the implications of these findings, we carried out simulations of the Atlanta urban environment and found that liquid-liquid phase separation can result in increased concentrations of gas-phase NO(3) and N(2)O(5) due to decreased particle uptake of N(2)O(5). PMID:22847443

  7. Effects of Liquid-Phase Composition on Its Migration during Liquid-Phase Sintering of Cemented Carbide

    NASA Astrophysics Data System (ADS)

    Fan, Peng; Guo, Jun; Fang, Zhigang Zak; Prichard, Paul

    2009-08-01

    Functionally graded composite materials (FGM composites) with a gradient of matrix phase can offer improved properties. Liquid-phase sintering is one of the approaches for making such materials with a desired gradient of the matrix phase by controlling the redistribution of the liquid phase during sintering. The present study on cemented carbide, WC-Co, demonstrates that the composition of the liquid phase (cobalt phase) is one of the key factors controlling the liquid redistribution. The dependence of the final gradient of the cobalt phase after sintering on its own chemical composition profile is quantitatively established, enabling the design and manufacture of WC-Co with a cobalt-phase-volume gradient via predesigned gradients of carbon content in the system.

  8. Methods to control phase inversions and enhance mass transfer in liquid-liquid dispersions

    DOEpatents

    Tsouris, Constantinos; Dong, Junhang

    2002-01-01

    The present invention is directed to the effects of applied electric fields on liquid-liquid dispersions. In general, the present invention is directed to the control of phase inversions in liquid-liquid dispersions. Because of polarization and deformation effects, coalescence of aqueous drops is facilitated by the application of electric fields. As a result, with an increase in the applied voltage, the ambivalence region is narrowed and shifted toward higher volume fractions of the dispersed phase. This permits the invention to be used to ensure that the aqueous phase remains continuous, even at a high volume fraction of the organic phase. Additionally, the volume fraction of the organic phase may be increased without causing phase inversion, and may be used to correct a phase inversion which has already occurred. Finally, the invention may be used to enhance mass transfer rates from one phase to another through the use of phase inversions.

  9. Solid-liquid phase boundaries of lens protein solutions.

    PubMed Central

    Berland, C R; Thurston, G M; Kondo, M; Broide, M L; Pande, J; Ogun, O; Benedek, G B

    1992-01-01

    We report measurement of the solid-liquid phase boundary, or liquidus line, for aqueous solutions of three pure calf gamma-crystallin proteins: gamma II, gamma IIIa, and gamma IIIb. We also studied the liquidus line for solutions of native gamma IV-crystallin calf lens protein, which consists of 85% gamma IVa/15% gamma IVb. In all four proteins the liquidus phase boundaries lie higher in temperature than the previously determined liquid-liquid coexistence curves. Thus, over the range of concentration and temperature for which liquid-liquid phase separation occurs, the coexistence of a protein crystal phase with a protein liquid solution phase is thermodynamically stable relative to the metastable separated liquid phases. The location of the liquidus lines clearly divides these four crystallin proteins into two groups: those in which liquidus lines flatten at temperatures greater than 70 degrees C: gamma IIIa and gamma IV, and those in which liquidus lines flatten at temperatures less than 50 degrees C: gamma II and gamma IIIb. We have analyzed the form of the liquidus lines by using specific choices for the structures of the Gibbs free energy in solution and solid phases. By applying the thermodynamic conditions for equilibrium between the two phases to the resulting chemical potentials, we can estimate the temperature-dependent free energy change upon binding of protein and water into the solid phase. PMID:1741375

  10. Non-aqueous electrolyte for lithium-ion battery

    DOEpatents

    Amine, Khalil; Zhang, Lu; Zhang, Zhengcheng

    2016-01-26

    A substantially non-aqueous electrolyte solution includes an alkali metal salt, a polar aprotic solvent, and an organophosphorus compound of Formula IA, IB, or IC: ##STR00001## where R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are each independently hydrogen, halogen, alkyl, alkenyl, alkynyl, cycloalkyl, aryl, heterocyclyl, heteroaryl, alkoxy, alkenoxy, alkynoxy, cycloalkoxy, aryloxy, heterocyclyloxy, heteroaryloxy, siloxyl, silyl, or organophosphatyl; R.sup.5 and R.sup.6 are each independently alkyl, alkenyl, alkynyl, cycloalkyl, aryl, heterocyclyl, or heteroaryl; R.sup.7 is ##STR00002## and R.sup.8, R.sup.9 and R.sup.10 are each independently alkyl, cycloalkyl, aryl, heterocyclyl, or heteroaryl; provided that if the organophosphorus compound is of Formula IB, then at least one of R.sup.5, and R.sup.6 are other than hydrogen, alkyl, or alkenyl; and if the organophosphorus compound is of Formula IC, then the electrolyte solution does not include 4-methylene-1,3-dioxolan-2-one or 4,5-dimethylene-1,3-dioxolan-2-one.

  11. Structure of liquid phosphorus: A liquid-liquid phase transition via constant-pressure first-principles molecular dynamics

    NASA Astrophysics Data System (ADS)

    Morishita, Tetsuya

    2001-12-01

    Constant-pressure first-principles molecular dynamics simulations have been carried out to study structural phase transitions of liquid black phosphorus. By compressing the tetrahedral molecular liquid (a low-pressure phase), a structural phase transition from the molecular to polymeric liquid (a high-pressure phase) was successfully realized just as observed in the recent experiment by Katayama et al. [Nature 170 (2000) 403]. Structural properties in the polymeric liquid were investigated and it is found that the covalent p-state bonds are dominant within the first nearest neighbors of each atom. However, further compression of the polymeric liquid shows that the covalent bonding is weakened as pressure is increased. As a result, liquid phosphorus becomes similar to the simple liquid in which atoms form a close-packed structure at very high pressure.

  12. Phase behavior of lysozyme solutions in the liquid-liquid phase coexistence region at high hydrostatic pressures.

    PubMed

    Schulze, Julian; Möller, Johannes; Weine, Jonathan; Julius, Karin; König, Nico; Nase, Julia; Paulus, Michael; Tolan, Metin; Winter, Roland

    2016-05-25

    We present results from small-angle X-ray scattering and turbidity measurements on the effect of high hydrostatic pressure on the phase behavior of dense lysozyme solutions in the liquid-liquid phase separation region, and characterize the underlying intermolecular protein-protein interactions as a function of temperature and pressure under charge-screening conditions (0.5 M NaCl). A reentrant liquid-liquid phase separation region is observed at elevated pressures, which may originate in the pressure dependence of the solvent-mediated protein-protein interaction. A temperature-pressure-concentration phase diagram was constructed for highly concentrated lysozyme solutions over a wide range of temperatures, pressures and protein concentrations including the critical region of the liquid-liquid miscibility gap. PMID:27165990

  13. Comparing two tetraalkylammonium ionic liquids. I. Liquid phase structure

    NASA Astrophysics Data System (ADS)

    Lima, Thamires A.; Paschoal, Vitor H.; Faria, Luiz F. O.; Ribeiro, Mauro C. C.; Giles, Carlos

    2016-06-01

    X-ray scattering experiments at room temperature were performed for the ionic liquids n-butyl-trimethylammonium bis(trifluoromethanesulfonyl)imide, [N1114][NTf2], and methyl-tributylammonium bis(trifluoromethanesulfonyl)imide, [N1444][NTf2]. The peak in the diffraction data characteristic of charge ordering in [N1444][NTf2] is shifted to longer distances in comparison to [N1114][NTf2], but the peak characteristic of short-range correlations is shifted in [N1444][NTf2] to shorter distances. Molecular dynamics (MD) simulations were performed for these ionic liquids using force fields available from the literature, although with new sets of partial charges for [N1114]+ and [N1444]+ proposed in this work. The shifting of charge and adjacency peaks to opposite directions in these ionic liquids was found in the static structure factor, S(k), calculated by MD simulations. Despite differences in cation sizes, the MD simulations unravel that anions are allowed as close to [N1444]+ as to [N1114]+ because anions are located in between the angle formed by the butyl chains. The more asymmetric molecular structure of the [N1114]+ cation implies differences in partial structure factors calculated for atoms belonging to polar or non-polar parts of [N1114][NTf2], whereas polar and non-polar structure factors are essentially the same in [N1444][NTf2]. Results of this work shed light on controversies in the literature on the liquid structure of tetraalkylammonium based ionic liquids.

  14. Comparing two tetraalkylammonium ionic liquids. I. Liquid phase structure.

    PubMed

    Lima, Thamires A; Paschoal, Vitor H; Faria, Luiz F O; Ribeiro, Mauro C C; Giles, Carlos

    2016-06-14

    X-ray scattering experiments at room temperature were performed for the ionic liquids n-butyl-trimethylammonium bis(trifluoromethanesulfonyl)imide, [N1114][NTf2], and methyl-tributylammonium bis(trifluoromethanesulfonyl)imide, [N1444][NTf2]. The peak in the diffraction data characteristic of charge ordering in [N1444][NTf2] is shifted to longer distances in comparison to [N1114][NTf2], but the peak characteristic of short-range correlations is shifted in [N1444][NTf2] to shorter distances. Molecular dynamics (MD) simulations were performed for these ionic liquids using force fields available from the literature, although with new sets of partial charges for [N1114](+) and [N1444](+) proposed in this work. The shifting of charge and adjacency peaks to opposite directions in these ionic liquids was found in the static structure factor, S(k), calculated by MD simulations. Despite differences in cation sizes, the MD simulations unravel that anions are allowed as close to [N1444](+) as to [N1114](+) because anions are located in between the angle formed by the butyl chains. The more asymmetric molecular structure of the [N1114](+) cation implies differences in partial structure factors calculated for atoms belonging to polar or non-polar parts of [N1114][NTf2], whereas polar and non-polar structure factors are essentially the same in [N1444][NTf2]. Results of this work shed light on controversies in the literature on the liquid structure of tetraalkylammonium based ionic liquids. PMID:27306015

  15. Liquid-Phase Electroepitaxy of Semiconductors

    NASA Astrophysics Data System (ADS)

    Dost, Sadik

    The chapter presents a review of the growth of single-crystal bulk semiconductors by liquid-phase electroepitaxy (LPEE). Following a short introduction, early modeling and theoretical studies on LPEE are briefly introduced. Recent experimental results on LPEE growth of GaAs/GaInAs single crystals under a static applied magnetic field are discussed in detail. The results of three-dimensional numerical simulations carried out for LPEE growth of GaAs under various electric and magnetic field levels are presented. The effect of magnetic field nonuniformities is numerically examined. Crystal growth experiments show that the application of a static magnetic field in LPEE growth of GaAs increases the growth rate very significantly. A continuum model to predict such high growth rates is also presented. The introduction of a new electric mobility in the model, i.e., the electromagnetic mobility, allows accurate predictions of both the growth rate and the growth interface shape. Space limitation required the citation of a limited number of references related to LPEE [29.1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73]. For details of many aspects of the LPEE growth process and its historical developments, the reader is referred to these references and also others cited therein.

  16. Ferrofluid-based liquid-phase microextraction.

    PubMed

    Shi, Zhi-Guo; Zhang, Yufeng; Lee, Hian Kee

    2010-11-19

    A new mode of liquid-phase microextraction based on a ferrofluid has been developed. The ferrofluid was composed of silica-coated magnetic particles and 1-octanol as the extractant solvent. The 1-octanol was firmly confined within the silica-coated particles, preventing it from being lost during extraction. Sixteen polycyclic aromatic hydrocarbons (PAHs) were used as model compounds in the development and evaluation of the extraction procedure in combination with gas chromatography-mass spectrometry. Parameters affecting the extraction efficiency were investigated in detail. The optimal conditions were as follows: 20mL sample volume, 10mg of the silica-coated magnetic particles (28mg of ferrofluid), agitation at 20Hz, 20min extraction time, and 2min by sonication with 100μL acetonitrile as the final extraction solvent. Under optimal extraction conditions, enrichment factors ranging from 102- to 173-fold were obtained for the analytes. The limits of detection and the limits of quantification were in the range of 16.8 and 56.7pgmL(-1) and 0.06 and 0.19ngmL(-1), respectively. The linearities were between 0.5-100 and 1-100ngmL(-1) for different PAHs. As the ferrofluid can respond to and be attracted by a magnet, the extraction can be easily achieved by reciprocating movement of an external magnet that served to agitate the sample. No other devices were needed in this new approach of extraction. This new technique is affordable, efficient and convenient for microextraction, and offers portability for potential onsite extraction. PMID:20961552

  17. Liquid-Liquid Phase Transformation in Silicon: Evidence from First-Principles Molecular Dynamics Simulations

    NASA Astrophysics Data System (ADS)

    Jakse, N.; Pasturel, A.

    2007-11-01

    We report results of first principles molecular dynamics simulations that confirm early speculations on the presence of liquid-liquid phase transition in undercooled silicon. However, we find that structural and electronic properties of both low-density liquid (LDL) and high-density liquid (HDL) phases are quite different from those obtained by empirical calculations, the difference being more pronounced for the HDL phase. The discrepancy between quantum and classical simulations is attributed to the inability of empirical potentials to describe changes in chemical bonds induced by density and temperature variations.

  18. Phase Diagram Characterization Using Magnetic Beads as Liquid Carriers.

    PubMed

    Blumenschein, Nicholas; Han, Daewoo; Steckl, Andrew J

    2015-01-01

    Magnetic beads with ~1.9 µm average diameter were used to transport microliter volumes of liquids between contiguous liquid segments with a tube for the purpose of investigating phase change of those liquid segments. The magnetic beads were externally controlled using a magnet, allowing for the beads to bridge the air valve between the adjacent liquid segments. A hydrophobic coating was applied to the inner surface of the tube to enhance the separation between two liquid segments. The applied magnetic field formed an aggregate cluster of magnetic beads, capturing a certain liquid amount within the cluster that is referred to as carry-over volume. A fluorescent dye was added to one liquid segment, followed by a series of liquid transfers, which then changed the fluorescence intensity in the neighboring liquid segment. Based on the numerical analysis of the measured fluorescence intensity change, the carry-over volume per mass of magnetic beads has been found to be ~2 to 3 µl/mg. This small amount of liquid allowed for the use of comparatively small liquid segments of a couple hundred microliters, enhancing the feasibility of the device for a lab-in-tube approach. This technique of applying small compositional variation in a liquid volume was applied to analyzing the binary phase diagram between water and the surfactant C12E5 (pentaethylene glycol monododecyl ether), leading to quicker analysis with smaller sample volumes than conventional methods. PMID:26381055

  19. Transient-Liquid-Phase and Liquid-Film-Assisted Joining ofCeramics

    SciTech Connect

    Sugar, Joshua D.; McKeown, Joseph T.; Akashi, Takaya; Hong, SungM.; Nakashima, Kunihiko; Glaeser, Andreas M.

    2005-02-09

    Two joining methods, transient-liquid-phase (TLP) joining and liquid-film-assisted joining (LFAJ), have been used to bond alumina ceramics. Both methods rely on multilayer metallic interlayers designed to form thin liquid films at reduced temperatures. The liquid films either disappear by interdiffusion (TLP) or promote ceramic/metal interface formation and concurrent dewetting of the liquid film (LFAJ). Progress on extending the TLP method to lower temperatures by combining low-melting-point (<450 C) liquids and commercial reactive-metal brazes is described. Recent LFAJ work on joining alumina to niobium using copper films is presented.

  20. The effect of graphene on liquid-crystalline blue phases

    NASA Astrophysics Data System (ADS)

    Lavrič, M.; Tzitzios, V.; Kralj, S.; Cordoyiannis, G.; Lelidis, I.; Nounesis, G.; Georgakilas, V.; Amenitsch, H.; Zidanšek, A.; Kutnjak, Z.

    2013-09-01

    The stabilization of liquid-crystalline blue phases is recently attracting considerable interest because of the envisioned applications in fast optical displays and tunable photonic crystals. We report on the effect of surface-functionalized graphene nanosheets on the blue phase range of a chiral liquid crystal. Calorimetric and optical measurements, reproducible on heating and cooling, demonstrate that the resulting soft nanocomposite exhibits an increased blue phase temperature stability range for a minute concentration of dispersed graphene. The impact is stronger on the ordered, cubic structured blue phase I. These findings suggest that anisotropic nanoparticles may be of great usefulness for stabilizing blue phases.

  1. Ultra fast polymer network blue phase liquid crystals

    NASA Astrophysics Data System (ADS)

    Hussain, Zakir; Masutani, Akira; Danner, David; Pleis, Frank; Hollfelder, Nadine; Nelles, Gabriele; Kilickiran, Pinar

    2011-06-01

    Polymer-stabilization of blue phase liquid crystal systems within a host polymer network are reported, which enables ultrafast switching flexible displays. Our newly developed method to stabilize the blue phase in an existing polymer network (e.g., that of a polymer network liquid crystal; PNLC) has shown wide temperature stability and fast response speeds. Systems where the blue phase is stabilized in an already existing polymer network are attractive candidates for ultrafast LCDs. The technology also promises to be applied to flexible PNLC and/or polymer dispersed liquid crystal (PDLC) displays using plastic substrate such as polyethylene terephthalate (PET).

  2. A NEW TWO-PHASE FLOW AND TRANSPORT MODEL WITH INTERPHASE MASS EXCHANGE

    EPA Science Inventory

    The focus of this numerical investigation is on modelling the emplacement and subsequent removal, through dissolution, of a Denser-than-water Non-Aqueous Phase Liquid (DNAPL) in a saturated groundwater system. pecifically the model must address two flow and transport regimes. irs...

  3. Measurements of liquid-phase turbulence in gas-liquid two-phase flows using particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Zhou, Xinquan; Doup, Benjamin; Sun, Xiaodong

    2013-12-01

    Liquid-phase turbulence measurements were performed in an air-water two-phase flow loop with a circular test section of 50 mm inner diameter using a particle image velocimetry (PIV) system. An optical phase separation method--planar laser-induced fluorescence (PLIF) technique—which uses fluorescent particles and an optical filtration technique, was employed to separate the signals of the fluorescent seeding particles from those due to bubbles and other noises. An image pre-processing scheme was applied to the raw PIV images to remove the noise residuals that are not removed by the PLIF technique. In addition, four-sensor conductivity probes were adopted to measure the radial distribution of the void fraction. Two benchmark tests were performed: the first was a comparison of the PIV measurement results with those of similar flow conditions using thermal anemometry from previous studies; the second quantitatively compared the superficial liquid velocities calculated from the local liquid velocity and void fraction measurements with the global liquid flow rate measurements. The differences of the superficial liquid velocity obtained from the two measurements were bounded within ±7% for single-phase flows and two-phase bubbly flows with the area-average void fraction up to 18%. Furthermore, a preliminary uncertainty analysis was conducted to investigate the accuracy of the two-phase PIV measurements. The systematic uncertainties due to the circular pipe curvature effects, bubble surface reflection effects and other potential uncertainty sources of the PIV measurements were discussed. The purpose of this work is to facilitate the development of a measurement technique (PIV-PLIF) combined with image pre-processing for the liquid-phase turbulence in gas-liquid two-phase flows of relatively high void fractions. The high-resolution data set can be used to more thoroughly understand two-phase flow behavior, develop liquid-phase turbulence models, and assess high

  4. Electron-solid and electron-liquid phases in graphene

    NASA Astrophysics Data System (ADS)

    Knoester, M. E.; Papić, Z.; Morais Smith, C.

    2016-04-01

    We investigate the competition between electron-solid and quantum-liquid phases in graphene, which arise in partially filled Landau levels. The differences in the wave function describing the electrons in the presence of a perpendicular magnetic field in graphene with respect to the conventional semiconductors, such as GaAs, can be captured in a form factor which carries the Landau-level index. This leads to a quantitative difference in the electron-solid and -liquid energies. For the lowest Landau level, there is no difference in the wave function of relativistic and nonrelativistic systems. We compute the cohesive energy of the solid phase analytically using a Hartree-Fock Hamiltonian. The liquid energies are computed analytically as well as numerically, using exact diagonalization. We find that the liquid phase dominates in the n =1 Landau level, whereas the Wigner crystal and electron-bubble phases become more prominent in the n =2 and 3 Landau level.

  5. Activation of Immobilized Lipase in Non-Aqueous Systems by Hydrophobic Poly-DL-Tryptophan Tethers

    PubMed Central

    Schilke, Karl F.; Kelly, Christine

    2014-01-01

    Many industrially important reactions use immobilized enzymes in non-aqueous, organic systems, particularly for the production of chiral compounds such as pharmaceutical precursors. The addition of a spacer molecule (“tether”) between a supporting surface and enzyme often substantially improves the activity and stability of enzymes in aqueous solution. Most “long” linkers (e.g. polyethylene oxide derivatives) are relatively hydrophilic, improving the solubility of the linker-enzyme conjugate in polar environments, but this provides little benefit in non-polar environments such as organic solvents. We present a novel method for the covalent immobilization of enzymes on solid surfaces using a long, hydrophobic polytryptophan tether. Candida antarctica lipase B (CALB) was covalently immobilized on non-porous, functionalized 1-μm silica microspheres, with and without an intervening hydrophobic poly-DL-tryptophan tether (n ≈ 78). The polytryptophan-tethered enzyme exhibited 35 times greater esterification of n-propanol with lauric acid in the organic phase and five times the hydrolytic activity against pnitrophenol palmitate, compared to the activity of the same enzyme immobilized without tethers. In addition, the hydrophobic tethers caused the silica microspheres to disperse more readily in the organic phase, while the surface-immobilized control treatment was less lipophilic and quickly settled out of the organic phase when the suspensions were not vigorously mixed. PMID:18393315

  6. Apparatus for the premixed gas phase combustion of liquid fuels

    SciTech Connect

    Roffe, G.A.; Trucco, H.A.

    1981-04-21

    This invention relates to improvements in the art of liquid fuel combustion and, more particularly, concerns a method and apparatus for the controlled gasification of liquid fuels, the thorough premixing of the then gasified fuel with air and the subsequent gas-phase combustion of the mixture to produce a flame substantially free of soot, carbon monoxide, nitric oxide and unburned fuel.

  7. Solid–Liquid Phase Change Driven by Internal Heat Generation

    SciTech Connect

    John Crepeau; Ali s. Siahpush

    2012-07-01

    This article presents results of solid-liquid phase change, the Stefan Problem, where melting is driven internal heat generation, in a cylindrical geometry. The comparison between a quasi-static analytical solution for Stefan numbers less than one and numerical solutions shows good agreement. The computational results of phase change with internal heat generation show how convection cells form in the liquid region. A scale analysis of the same problem shows four distinct regions of the melting process.

  8. Diffusion mass transport in liquid phase epitaxial growth of semiconductors

    SciTech Connect

    Dost, S.; Qin, Z.; Kimura, M.

    1996-12-01

    A numerical simulation model for the mass transport occurring during the liquid phase epitaxial growth of AlGaAs is presented. The mass transport equations in the liquid and solid phases, and the relationships between concentrations and temperature obtained from the phase diagram constitute the governing equations. These equations together with appropriate interface and boundary conditions were solved numerically by the Finite Element Method. Numerical results show the importance of diffusion into the solid phase, affecting the composition of grown layers. Simulation results agree with experiments.

  9. Gas-Liquid Flows and Phase Separation

    NASA Technical Reports Server (NTRS)

    McQuillen, John

    2004-01-01

    Common issues for space system designers include:Ability to Verify Performance in Normal Gravity prior to Deployment; System Stability; Phase Accumulation & Shedding; Phase Separation; Flow Distribution through Tees & Manifolds Boiling Crisis; Heat Transfer Coefficient; and Pressure Drop.The report concludes:Guidance similar to "A design that operates in a single phase is less complex than a design that has two-phase flow" is not always true considering the amount of effort spent on pressurizing, subcooling and phase separators to ensure single phase operation. While there is still much to learn about two-phase flow in reduced gravity, we have a good start. Focus now needs to be directed more towards system level problems .

  10. Design and optimization of disintegrating pellets of MCC by non-aqueous extrusion process using statistical tools.

    PubMed

    Gurram, Rajesh Kumar; Gandra, Suchithra; Shastri, Nalini R

    2016-03-10

    The objective of the study was to design and optimize a disintegrating pellet formulation of microcrystalline cellulose by non-aqueous extrusion process for a water sensitive drug using various statistical tools. Aspirin was used as a model drug. Disintegrating matrix pellets of aspirin using propylene glycol as a non-aqueous granulation liquid and croscarmellose as a disintegrant was developed. Plackett-Burman design was initially conducted to screen and identify the significant factors. Final optimization of formula was performed by response surface methodology using a central composite design. The critical attributes of the pellet dosage forms (dependent variables); disintegration time, sphericity and yield were predicted with adequate accuracy based on the regression model. Pareto charts and contour charts were studied to understand the influence of factors and predict the responses. A design space was constructed to meet the desirable targets of the responses in terms of disintegration time <5min, maximum yield, sphericity >0.95 and friability <1.7%. The optimized matrix pellets were enteric coated using Eudragit L 100. The drug release from the enteric coated pellets after 30min in the basic media was ~93% when compared to ~77% from the marketed pellets. The delayed release pellets stored at 25°C/60% RH were stable for a period of 10mo. In conclusion, it can be stated that the developed process for disintegrating pellets using non-aqueous granulating agents can be used as an alternative technique for various water sensitive drugs, circumventing the application of volatile organic solvents in conventional drug layering on inert cores. The scope of this study can be further extended to hydrophobic drugs, which may benefit from the rapid disintegration property and the use of various hydrophilic excipients used in the optimized pellet formulation to enhance dissolution and in turn improve bioavailability. PMID:26812204

  11. Comparison of liquid-phase and gas-phase pure thermal cracking on n-hexadecane

    SciTech Connect

    Wu, G.; Katsumura, Yosuke; Matsuura, Chihiro; Ishigure, Kenkichi; Kubo, Junichi

    1996-12-01

    Thermal cracking of n-hexadecane in the mild temperature (330--375 C) range has been investigated in liquid and gas phases. The kinetic data of liquid-phase cracking are shown to be very similar to those of gas-phase cracking. However, the pattern and distribution of the products are greatly phase dependent. In liquid-phase cracking, there is an equimolar distribution of n-alkane and 1-alkene products in the C{sub 3}--C{sub 13} range at low conversion; when the conversion is increased, more alkanes than alkenes are produced. To the contrary, more alkenes than alkanes are always determined in products from gas-phase cracking. Liquid-phase cracking gives a low selectivity of gas products and a high selectivity of addition compounds (C{sub 18}--C{sub 30}), whereas gas-phase cracking produces a large amount of gas products and no addition compounds. The phase dependence of products can be interpreted in terms of a low concentration of hexadecane, under which {beta}-scission occurs more preferentially than in liquid phase. Reaction mechanisms are suggested based on the product analysis to account for cracking behaviors of liquid-phase and gas-phase cracking.

  12. Liquid phase reaction-bonding of structural ceramics and composites

    SciTech Connect

    Chiang, Y.M. . Dept. of Materials Science and Engineering)

    1988-01-01

    Synthesis of ceramics via the reaction of a solid precursor with either a gas or liquid phase has a number of advantages compared to conventional sintering technology. These advantages are known for gas-phase processes. The authors have explored the potential for synthesizing high performance ceramics in the model system reaction-bonded silicon carbide, in which liquid silicon is used to infiltrate carbonaceous preforms. In this paper results are presented that illustrate the use of alloyed-melts to obtain dense silicon carbide composites with residual refractory silicide phases, such as MoSi/sub 2/, rather than the residual silicon phase which has heretofore limited high temperature properties. Infiltration processing considerations, such as the ultimate infiltration dimensions possible in the presence of simultaneous reaction, are discussed. Microstructure and mechanical properties characterization in the SIC-MoSi/sub 2/ system are presented. Other refractory ceramics systems to which liquid-phase reaction-bonding may be applied are discussed.

  13. The liquid to vapor phase transition in excited nuclei

    SciTech Connect

    Elliott, J.B.; Moretto, L.G.; Phair, L.; Wozniak, G.J.; Beaulieu, L.; Breuer, H.; Korteling, R.G.; Kwiatkowski, K.; Lefort, T.; Pienkowski, L.; Ruangma, A.; Viola, V.E.; Yennello, S.J.

    2001-05-08

    For many years it has been speculated that excited nuclei would undergo a liquid to vapor phase transition. For even longer, it has been known that clusterization in a vapor carries direct information on the liquid-vapor equilibrium according to Fisher's droplet model. Now the thermal component of the 8 GeV/c pion + 197 Au multifragmentation data of the ISiS Collaboration is shown to follow the scaling predicted by Fisher's model, thus providing the strongest evidence yet of the liquid to vapor phase transition.

  14. Structural crossover in a supercooled metallic liquid and the link to a liquid-to-liquid phase transition

    NASA Astrophysics Data System (ADS)

    Lan, S.; Blodgett, M.; Kelton, K. F.; Ma, J. L.; Fan, J.; Wang, X.-L.

    2016-05-01

    Time-resolved synchrotron measurements were carried out to capture the structure evolution of an electrostatically levitated metallic-glass-forming liquid during free cooling. The experimental data shows a crossover in the liquid structure at ˜1000 K, about 115 K below the melting temperature and 150 K above the crystallization temperature. The structure change is characterized by a dramatic growth in the extended-range order below the crossover temperature. Molecular dynamics simulations have identified that the growth of the extended-range order was due to an increased correlation between solute atoms. These results provide structural evidence for a liquid-to-liquid-phase-transition in the supercooled metallic liquid.

  15. Relationship between the liquid liquid phase transition and dynamic behaviour in the Jagla model

    NASA Astrophysics Data System (ADS)

    Xu, Limei; Ehrenberg, Isaac; Buldyrev, Sergey V.; Stanley, H. Eugene

    2006-09-01

    Using molecular dynamics simulations, we study a spherically symmetric 'two-scale' Jagla potential with both repulsive and attractive ramps. This potential displays a liquid-liquid phase transition with a positively sloped coexistence line ending at a critical point well above the equilibrium melting line. We study the dynamic behaviour in the vicinity of this liquid-liquid critical point. Below the critical point, we find that the dynamics in the more ordered high density liquid (HDL) are much slower then the dynamics in the less ordered low density liquid (LDL). Moreover, the behaviour of the diffusion constant and relaxation time in the HDL phase follows approximately an Arrhenius law, while in the LDL phase the slope of the Arrhenius fit increases upon cooling. Above the critical pressure, as we cool the system at constant pressure, the behaviour of the dynamics smoothly changes with temperature. It resembles the behaviour of the LDL at high temperatures and resembles the behaviour of the HDL at low temperatures. This dynamic crossover happens in the vicinity of the Widom line (the extension of the coexistence line into the one-phase region) which also has a positive slope. Our work suggests a possible general relation between a liquid-liquid phase transition and the change in dynamics.

  16. Green aspects, developments and perspectives of liquid phase microextraction techniques.

    PubMed

    Spietelun, Agata; Marcinkowski, Łukasz; de la Guardia, Miguel; Namieśnik, Jacek

    2014-02-01

    Determination of analytes at trace levels in complex samples (e.g. biological or contaminated water or soils) are often required for the environmental assessment and monitoring as well as for scientific research in the field of environmental pollution. A limited number of analytical techniques are sensitive enough for the direct determination of trace components in samples and, because of that, a preliminary step of the analyte isolation/enrichment prior to analysis is required in many cases. In this work the newest trends and innovations in liquid phase microextraction, like: single-drop microextraction (SDME), hollow fiber liquid-phase microextraction (HF-LPME), and dispersive liquid-liquid microextraction (DLLME) have been discussed, including their critical evaluation and possible application in analytical practice. The described modifications of extraction techniques deal with system miniaturization and/or automation, the use of ultrasound and physical agitation, and electrochemical methods. Particular attention was given to pro-ecological aspects therefore the possible use of novel, non-toxic extracting agents, inter alia, ionic liquids, coacervates, surfactant solutions and reverse micelles in the liquid phase microextraction techniques has been evaluated in depth. Also, new methodological solutions and the related instruments and devices for the efficient liquid phase micoextraction of analytes, which have found application at the stage of procedure prior to chromatographic determination, are presented. PMID:24401382

  17. Suppression of phase transitions in a confined rodlike liquid crystal.

    PubMed

    Grigoriadis, Christos; Duran, Hatice; Steinhart, Martin; Kappl, Michael; Butt, Hans-Jürgen; Floudas, George

    2011-11-22

    The nematic-to-isotropic, crystal-to-nematic, and supercooled liquid-to-glass temperatures are studied in the liquid crystal 4-pentyl-4'-cyanobiphenyl (5CB) confined in self-ordered nanoporous alumina. The nematic-to-isotropic and the crystal-to-nematic transition temperatures are reduced linearly with the inverse pore diameter. The finding that the crystalline phase is completely suppressed in pores having diameters of 35 nm and below yields an estimate of the critical nucleus size. The liquid-to-glass temperature is reduced in confinement as anticipated by the model of rotational diffusion within a cavity. These results provide the pertinent phase diagram for a confined liquid crystal and are of technological relevance for the design of liquid crystal-based devices with tunable optical, thermal, and dielectric properties. PMID:21974835

  18. Non-aqueous Electrode Processing and Construction of Lithium-ion Coin Cells.

    PubMed

    Stein, Malcolm; Chen, Chien-Fan; Robles, Daniel J; Rhodes, Christopher; Mukherjee, Partha P

    2016-01-01

    Research into new and improved materials to be utilized in lithium-ion batteries (LIB) necessitates an experimental counterpart to any computational analysis. Testing of lithium-ion batteries in an academic setting has taken on several forms, but at the most basic level lies the coin cell construction. In traditional LIB electrode preparation, a multi-phase slurry composed of active material, binder, and conductive additive is cast out onto a substrate. An electrode disc can then be punched from the dried sheet and used in the construction of a coin cell for electrochemical evaluation. Utilization of the potential of the active material in a battery is critically dependent on the microstructure of the electrode, as an appropriate distribution of the primary components are crucial to ensuring optimal electrical conductivity, porosity, and tortuosity, such that electrochemical and transport interaction is optimized. Processing steps ranging from the combination of dry powder, wet mixing, and drying can all critically affect multi-phase interactions that influence the microstructure formation. Electrochemical probing necessitates the construction of electrodes and coin cells with the utmost care and precision. This paper aims at providing a step-by-step guide of non-aqueous electrode processing and coin cell construction for lithium-ion batteries within an academic setting and with emphasis on deciphering the influence of drying and calendaring. PMID:26863503

  19. Liquid jet pumps for two-phase flows

    SciTech Connect

    Cunningham, R.G.

    1995-06-01

    Isothermal compression of a bubbly secondary fluid in a mixing-throat and diffuser is described by a one-dimensional flow model of a liquid-jet pump. Friction-loss coefficients used in the four equations may be determined experimentally, or taken from the literature. The model reduces to the liquid-jet gas compressor case if the secondary liquid is zero. Conversely, a zero secondary-gas flow reduces the liquid-jet gas and liquid (LJGL) model to that of the familiar liquid-jet liquid pump. A ``jet loss`` occurs in liquid-jet pumps if the nozzle tip is withdrawn from the entrance plane of the throat, and jet loss is included in the efficiency equations. Comparisons are made with published test data for liquid-jet liquid pumps and for liquid-jet gas compressors. The LJGL model is used to explore jet pump responses to two-phase secondary flows, nozzle-to-throat area ratio, and primary-jet velocity. The results are shown in terms of performance curves versus flow ratios. Predicted peak efficiencies are approximately 50 percent. Under sever operating conditions, LJGL pump performance curves exhibit maximum-flow ratios or cut-offs. Cut-offs occurs when two-phase secondary-flow steams attain sonic values at the entry of the mixing throat. A dimensionless number correlates flow-ratio cut-offs with pump geometry and operating conditions. Throat-entry choking of the secondary flow can be predicted, hence avoided, in designing jet pumps to hand two-phase fluids.

  20. Entropy Calculations for a Supercooled Liquid Crystalline Blue Phase

    ERIC Educational Resources Information Center

    Singh, U.

    2007-01-01

    We observed, using polarized light microscopy, the supercooling of the blue phase (BPI) of cholesteryl proprionate and measured the corresponding liquid crystalline phase transition temperatures. From these temperatures and additional published data we have provided, for the benefit of undergraduate physics students, a nontraditional example…

  1. Polarization-phase filtering of laser images of biological liquids

    NASA Astrophysics Data System (ADS)

    Ushenko, Yu. A.; Sidor, M.

    2013-06-01

    Our work is aimed at searching the possibilities to perform diagnostics and differentiation of structures inherent to liquid-crystal networks of blood plasma with various pathologies (health - breast cancer) by using the method to determine the coordinate distributions of phase shifts (phase maps) between orthogonal components of laser radiation amplitudes with the following statistical, fractal and singular analyses of these distributions.

  2. Low voltage blue phase liquid crystal for spatial light modulators.

    PubMed

    Peng, Fenglin; Lee, Yun-Han; Luo, Zhenyue; Wu, Shin-Tson

    2015-11-01

    We demonstrated a low-voltage polymer-stabilized blue phase liquid crystal (BPLC) for phase-only modulation with a liquid-crystal-on-silicon (LCoS). A new device configuration was developed, which allows the incident laser beam to traverse the BPLC layer four times before exiting the LCoS. As a result, the 2π phase change voltage is reduced to below 24 V in the visible region. The response time remains relatively fast (∼3  ms). The proposed device configuration enables widespread applications of BPLC spatial light modulators. PMID:26512528

  3. Fabrication of Janus droplets by evaporation driven liquid-liquid phase separation.

    PubMed

    Zhang, Qingquan; Xu, Meng; Liu, Xiaojun; Zhao, Wenfeng; Zong, Chenghua; Yu, Yang; Wang, Qi; Gai, Hongwei

    2016-04-11

    We present a universal and scalable method to fabricate Janus droplets based on evaporation driven liquid-liquid phase separation. In this work, the morphologies and chemical properties of separate parts of the Janus droplets can be flexibly regulated, and more complex Janus droplets (such as core-shell Janus droplets, ternary Janus droplets, and multiple Janus droplets) can be constructed easily. PMID:26983706

  4. Phase behavior and dynamics of a cholesteric liquid crystal

    SciTech Connect

    Roy, D.; Fragiadakis, D.; Roland, C. M.; Dabrowski, R.; Dziaduszek, J.; Urban, S.

    2014-02-21

    The synthesis, equation of state, phase diagram, and dielectric relaxation properties are reported for a new liquid crystal, 4{sup ′}-butyl-4-(2-methylbutoxy)azoxybenzene (4ABO5*), which exhibits a cholesteric phase at ambient temperature. The steepness of the intermolecular potential was characterized from the thermodynamic potential parameter, Γ = 4.3 ± 0.1 and the dynamic scaling exponent, γ = 3.5 ± 0.2. The difference between them is similar to that seen previously for nematic and smectic liquid crystals, with the near equivalence of Γ and γ consistent with the near constancy of the relaxation time of 4ABO5* at the cholesteric to isotropic phase transition (i.e., the clearing line). Thus, chirality does not cause deviations from the general relationship between thermodynamics and dynamics in the ordered phase of liquid crystals. The ionic conductivity of 4ABO5* shows strong coupling to the reorientational dynamics.

  5. Fast Method for Computing Chemical Potentials and Liquid-Liquid Phase Equilibria of Macromolecular Solutions.

    PubMed

    Qin, Sanbo; Zhou, Huan-Xiang

    2016-08-25

    Chemical potential is a fundamental property for determining thermodynamic equilibria involving exchange of molecules, such as between two phases of molecular systems. Previously, we developed the fast Fourier transform (FFT)-based method for Modeling Atomistic Protein-crowder interactions (FMAP) to calculate excess chemical potentials according to the Widom insertion. Intermolecular interaction energies were expressed as correlation functions and evaluated via FFT. Here, we extend this method to calculate liquid-liquid phase equilibria of macromolecular solutions. Chemical potentials are calculated by FMAP over a wide range of molecular densities, and the condition for coexistence of low- and high-density phases is determined by the Maxwell equal-area rule. When benchmarked on Lennard-Jones fluids, our method produces an accurate phase diagram at 18% of the computational cost of the current best method. Importantly, the gain in computational speed increases dramatically as the molecules become more complex, leading to many orders of magnitude in speed up for atomistically represented proteins. We demonstrate the power of FMAP by reporting the first results for the liquid-liquid coexistence curve of γII-crystallin represented at the all-atom level. Our method may thus open the door to accurate determination of phase equilibria for macromolecular mixtures such as protein-protein mixtures and protein-RNA mixtures, that are known to undergo liquid-liquid phase separation, both in vitro and in vivo. PMID:27327881

  6. Microgravity Studies of Liquid-Liquid Phase Transitions in Alumina-Yttria Melts

    NASA Technical Reports Server (NTRS)

    Guynes, Buddy (Technical Monitor); Weber, Richard; Nordine, Paul

    2004-01-01

    The scientific objective of this research is to increase the fundamental knowledge base for liquid- phase processing of technologically important oxide materials. The experimental objective is to define conditions and hardware requirements for microgravity flight experiments to test and expand the experimental hypotheses that: 1. Liquid phase transitions can occur in undercooled melts by a diffusionless process. 2. Onset of the liquid phase transition is accompanied by a large change in the temperature dependence of melt viscosity. Experiments on undercooled YAG (Y3A15012)- and rare earth oxide aluminate composition liquids demonstrated a large departure from an Arrhenian temperature dependence of viscosity. Liquid YAG is nearly inviscid at its 2240 K melting point. Glass fibers were pulled from melts undercooled by ca. 600 K indicating that the viscosity is on the order of 100 Pans (1000 Poise) at 1600 K. This value of viscosity is 500 times greater than that obtained by extrapolation of data for temperatures above the melting point of YAG. These results show that the liquids are extremely fragile and that the onset of the highly non-Arrhenian viscosity-temperature relationship occurs at a temperature considerably below the equilibrium melting point of the solid phases. Further results on undercooled alumina-yttria melts containing 23-42 mole % yttrium oxide indicate that a congruent liquid-liquid phase transition occurs in the undercooled liquids. The rates of transition are inconsistent with a diffusion-limited process. This research is directed to investigation of the scientifically interesting phenomena of polyamorphism and fragility in undercooled rare earth oxide aluminum oxide liquids. The results bear on the technologically important problem of producing high value rare earth-based optical materials.

  7. Micellar hexagonal phases in lyotropic liquid crystals

    NASA Astrophysics Data System (ADS)

    Amaral, L. Q.; Gulik, A.; Itri, R.; Mariani, P.

    1992-09-01

    The hexagonal cell parameter a of the system sodium dodecyl lauryl sulfate and water as a function of volume concentration cv in phase Hα shows the functional behavior expected for micelles of finite length: a~c-1/3v. The interpretation of x-ray data based on finite micelles leads to an alternative description of the hexagonal phase Hα: spherocylindrical micelles of constant radius with length that may grow along the range of the Hα phase. Results are compared with recent statistical-mechanical calculations for the isotropic I-Hα transition. The absence of diffraction in the direction perpendicular to the hexagonal plane is ascribed to polydispersity of micellar length, which also is a necessary condition for the occurrence of direct I-Hα transitions.

  8. Liquid and Solid Phases of 3He on Graphite

    NASA Astrophysics Data System (ADS)

    Gordillo, M. C.; Boronat, J.

    2016-04-01

    Recent heat-capacity experiments show quite unambiguously the existence of a liquid 3He phase adsorbed on graphite. This liquid is stable at an extremely low density, possibly one of the lowest found in nature. Previous theoretical calculations of the same system, and in strictly two dimensions, agree with the result that this liquid phase is not stable and the system is in the gas phase. We calculated the phase diagram of normal 3He adsorbed on graphite at T =0 using quantum Monte Carlo methods. Considering a fully corrugated substrate, we observe that at densities lower than 0.006 Å-2 the system is a very dilute gas that, at that density, is in equilibrium with a liquid of density 0.014 Å-2 . Our prediction matches very well the recent experimental findings on the same system. On the contrary, when a flat substrate is considered, no gas-liquid coexistence is found, in agreement with previous calculations. We also report results on the different solid structures, and on the corresponding phase transitions that appear at higher densities.

  9. CEC column behaviour of butyl and lauryl methacrylate monoliths prepared in non-aqueous media.

    PubMed

    Cantó-Mirapeix, Amparo; Herrero-Martínez, José M; Mongay-Fernández, Carlos; Simó-Alfonso, Ernesto F

    2009-02-01

    Polymeric monolithic stationary phases for capillary electrochromatography were prepared using two bulk monomers, butyl methacrylate (BMA) and lauryl methacrylate (LMA), by in situ polymerization in non-aqueous media. The effect of 1,4-butanediol/1-propanol ratio on porous properties was investigated separately for each monomer, keeping the proportion of monomers to pore-forming solvents fixed at 40:60 wt:wt. Also, mixtures of BMA and LMA at different 1,4-butanediol/1-propanol ratios were studied for tailoring the morphological features of the monolithic columns. The chromatographic performance of the different columns was evaluated by means of van Deemter plots of polycyclic aromatic hydrocarbons. Mercury-intrusion porosimetry, SEM, and nitrogen-adsorption measurements were also performed in order to understand their retention behaviour and porous properties. A comparison of these features was also performed for monoliths made with one bulk monomer (BMA or LMA) and with mixtures of both. These mixed monoliths showed satisfactory efficiencies and analysis times compared with those made with one bulk monomer; thus, the BMA-LMA monoliths constitute an attractive alternative to manipulate the electrochromatographic properties of methacrylate beds in CEC. PMID:19170053

  10. Nature of the first-order liquid-liquid phase transition in supercooled silicon

    NASA Astrophysics Data System (ADS)

    Zhao, G.; Yu, Y. J.; Tan, X. M.

    2015-08-01

    The first-order liquid-liquid phase transition in supercooled Si is revisited by long-time first-principle molecular dynamics simulations. As the focus of the present paper, its nature is revealed by analyzing the inherent structures of low-density liquid (LDL) and high-density liquid (HDL). Our results show that it is a transition between a sp3-hybridization LDL and a white-tin-like HDL. This uncovers the origin of the semimetal-metal transition accompanying it and also proves that HDL is the metastable extension of high temperature equilibrium liquid into the supercooled regime. The pressure-temperature diagram of supercooled Si thus can be regarded in some respects as shifted reflection of its crystalline phase diagram.

  11. Containerless Liquid-Phase Processing of Ceramic Materials

    NASA Technical Reports Server (NTRS)

    Weber, J. K. Richard (Principal Investigator); Nordine, Paul C.

    1996-01-01

    The present project builds on the results of research supported under a previous NASA grant to investigate containerless liquid-phase processing of molten ceramic materials. The research used an aero-acoustic levitator in combination with cw CO2 laser beam heating to achieve containerless melting, superheating, undercooling, and solidification of poorly-conducting solids and liquids. Experiments were performed on aluminum oxide, binary aluminum oxide-silicon dioxide materials, and oxide superconductors.

  12. Liquid-phase mixing of bipropellant doublets

    NASA Technical Reports Server (NTRS)

    Hoehn, F. W.; Rupe, J. H.; Sotter, J. G.

    1972-01-01

    Experimental results of unlike doublet mixing are correlated with an analytically derived equation predicting fluid cavitation. The correlation relates the minimum orifice pressure drop required to initiate cavitation, with the system back pressure, cold flow simulant vapor pressure, and the orifice flow discharge and contraction coefficients. Stream flow instabilities are also visually correlated with the onset of cavitation and orifice discharge coefficient measurements. The influence of cavitation on the characteristic phenomenon of hydraulic flip is observed for both circular and noncircular shaped orifices. For certain intermediate orifice lengths, some noncircular shapes are shown to produce more fully developed flows (shorter recovery lengths) and therefore a more cohesive jet, which in turn yields slightly higher cold flow mixing uniformities than circular shaped orifices of equal absolute length. The particular noncircular shaped elements evaluated are shown to be more sensitive to liquid stream misimpingement than the corresponding circular orifices.

  13. Microstructural development in transient liquid-phase bonding

    NASA Astrophysics Data System (ADS)

    Gale, W. F.; Wallach, E. R.

    1991-10-01

    The applicability of conventional models of the transient liquid-phase (TLP) bonding process to the joining of nickel using ternary Ni-Si-B insert metals is considered in this article. It is suggested that diffusion of boron out of the liquid and into the solid substrate before the equilibration of the liquid and solid phases can result in the development of significant boron concentrations in the substrate. This, in turn, leads to the precipitation of boride phases in the substrate during holding at bonding temperatures below the binary nickel-boron eutectic temperature. The formation of boride phases during holding at the bonding temperature is of importance, because first, it is not predicted by the standard models of the TLP process, and second, the borides are not removed by prolonged holding at the bonding temperature and therefore may influence the in-service properties of the joint. In contrast, when bonding above the binary nickel-boron eutectic temperature, localized liquation of the substrate takes place. This liquid region resolidifies following prolonged holding and does not result in the formation of persistent boride phases. Experimental support is presented for the formation of borides during bonding, and characterization of the boride phases formed in the substrate is described.

  14. The Molecular Structure of the Liquid Ordered Phase

    NASA Astrophysics Data System (ADS)

    Lyman, Edward

    2014-03-01

    Molecular dynamics simulations reveal substructures within the liquid-ordered phase of lipid bilayers. These substructures, identified in a 10 μsec all-atom trajectory of liquid-ordered/liquid-disordered coexistence (Lo/Ld) , are composed of saturated hydrocarbon chains packed with local hexagonal order, and separated by interstitial regions enriched in cholesterol and unsaturated chains. Lipid hydrocarbon chain order parameters calculated from the Lo phase are in excellent agreement with 2H NMR measurements; the local hexagonal packing is also consistent with 1H-MAS NMR spectra of the Lo phase, NMR diffusion experiments, and small angle X-ray- and neutron scattering. The balance of cholesterol-rich to local hexagonal order is proposed to control the partitioning of membrane components into the Lo regions. The latter have been frequently associated with formation of so-called rafts, platforms in the plasma membranes of cells that facilitate interaction between components of signaling pathways.

  15. Manipulating Liquids With Acoustic Radiation Pressure Phased Arrays

    NASA Technical Reports Server (NTRS)

    Oeftering, Richard C.

    1999-01-01

    High-intensity ultrasound waves can produce the effects of "Acoustic Radiation Pressure" (ARP) and "acoustic streaming." These effects can be used to propel liquid flows and to apply forces that can be used to move or manipulate floating objects or liquid surfaces. NASA's interest in ARP includes the remote-control agitation of liquids and the manipulation of bubbles and drops in liquid experiments and propellant systems. A high level of flexibility is attained by using a high-power acoustic phased array to generate, steer, and focus a beam of acoustic waves. This is called an Acoustic Radiation Pressure Phased Array, or ARPPA. In this approach, many acoustic transducer elements emit wavelets that converge into a single beam of sound waves. Electronically coordinating the timing, or "phase shift," of the acoustic waves makes it possible to form a beam with a predefined direction and focus. Therefore, a user can direct the ARP force at almost any desired point within a liquid volume. ARPPA lets experimenters manipulate objects anywhere in a test volume. This flexibility allow it to be used for multiple purposes, such as to agitate liquids, deploy and manipulate drops or bubbles, and even suppress sloshing in spacecraft propellant tanks.

  16. Rate Limited Diffusion and Dissolution of Multicomponent Nonaqueous Phase Liquids (NAPLs) and Effects on Mass Discharge in Groundwater

    NASA Astrophysics Data System (ADS)

    Padgett, M.; Tick, G.; Carroll, K. C.

    2014-12-01

    Remediation efforts and contaminant transport predictions generally neglect the complicated dissolution and transport behavior associated with multicomponent NAPL (Non-aqueous phase liquid) sources. Therefore, it is important to understand the diffusion and dissolution processes occurring in these multicomponent systems as a function of mole fraction, molecular similarity/dissimilarity, hydraulic, or nonideal factors. A series of laboratory scale NAPL-aqueous phase dissolution experiments were conducted to assess dissolution and intra-NAPL diffusion as a function of multicomponent NAPL composition (i.e. mole fraction) for both trichloroethene and toluene. These target compounds were selected as representative contaminants as they are commonly components of NAPL mixtures and they define both classes of NAPL (dense-DNAPL and light-LNAPL). Predetermined volumes of target NAPL were mixed with an insoluble n-hexadecane NAPL to create mixtures that vary by NAPL composition. The ideality of resulting target compound dissolution was evaluated by quantifying NAPL-phase activity coefficient through Raoult's Law analysis. The results show that dissolution from the NAPL mixtures behave ideally for mole fractions above 0.2. As the target compound fraction of the NAPL mixture get smaller, the dissolution behavior becomes increasingly more nonideal (i.e. greater NAPL-phase activity coefficients). Overall, the time-series batch experiments show that dissolution rates were consistent for various mole fraction ratios, indicating that intra-NAPL diffusion is not the rate-limiting control over aqueous concentrations or is not significantly controlled by NAPL composition-dependent factors. The results of this work will improve transport predictions, remediation design, and risk assessments especially for sites contaminated by complex NAPL mixtures.

  17. Liquid-liquid phase separation in supersaturated lysozyme solutions and associated precipitate formation/crystallization

    NASA Astrophysics Data System (ADS)

    Muschol, Martin; Rosenberger, Franz

    1997-08-01

    Using cloud point determinations, the phase boundaries (binodals) for metastable liquid-liquid (L-L) separation in supersaturated hen egg white lysozyme solutions with 3%, 5%, and 7% (w/v) NaCl at pH=4.5 and protein concentrations c between 40 and 400 mg/ml were determined. The critical temperature for the binodal increased approximately linearly with salt concentration. The coexisting liquid phases both remained supersaturated but differed widely in protein concentration. No salt repartitioning was observed between the initial and the two separated liquid phases. After the L-L separation, due to the presence of the high protein concentration phase, crystallization occurred much more rapidly than in the initial solution. At high initial protein concentrations, a metastable gel phase formed at temperatures above the liquid binodal. Both crystal nucleation and gel formation were accelerated in samples that had been cycled through the binodal. Solutions in the gel and L-L regions yielded various types of precipitates. Based on theoretical considerations, previous observations with other proteins, and our experimental results with lysozyme, a generic phase diagram for globular proteins is put forth. A limited region in the (T,c) plane favorable for the growth of protein single crystals is delineated.

  18. Liquid-Liquid Phase Separation in Supersaturated Lysozyme Solutions and Associated Precipitate Formation/Crystallization

    NASA Technical Reports Server (NTRS)

    Muschol, Martin; Rosenberger, Franz

    1997-01-01

    Using cloud point determinations, the phase boundaries (binodals) for metastable liquid-liquid (L-L) separation in supersaturated hen egg white lysozyme solutions with 3%, 5%, and 7% (wlv) NaCl at pH= 4.5 and protein concentrations c between 40 and 400 mg/ml were determined. The critical temperature for the binodal increased approximately linearly with salt concentration. The coexisting liquid phases both remained supersaturated but differed widely in protein concentration. No salt repartitioning was observed between the initial and the two separated liquid phases. After the L-L separation, due to the presence of the high protein concentration phase, crystallization occurred much more rapidly than in the initial solution. At high initial protein concentrations, a metastable gel phase formed at temperatures above the liquid binodal. Both crystal nucleation and gel formation were accelerated in samples that had been cycled through the binodal. Solutions in the gel and L-L regions yielded various types of precipitates. Based on theoretical considerations, previous observations with other proteins, and our experimental results with lysozyme, a generic phase diagram for globular proteins is put forth. A limited region in the (T,c) plane favorable for the growth of protein single crystals is delineated.

  19. Non-aqueous solution preparation of doped and undoped lixmnyoz

    DOEpatents

    Boyle, Timothy J.; Voigt, James A.

    1997-01-01

    A method for generation of phase-pure doped and undoped Li.sub.x Mn.sub.y O.sub.z precursors. The method of this invention uses organic solutions instead of aqueous solutions or nonsolution ball milling of dry powders to produce phase-pure precursors. These precursors can be used as cathodes for lithium-polymer electrolyte batteries. Dopants may be homogeneously incorporated to alter the characteristics of the powder.

  20. Effect of liquid viscosity on wave behavior in gas-liquid two-phase flow

    SciTech Connect

    Kondo, Yoshiyuki; Mori, Koji; Yagishita, Takuya; Nakabo, Akinobu

    1999-07-01

    Measurements of time-spatial distributions of liquid holdups for the vertical upward gas-liquid two-phase flow were carried out by using the supermultiple cross-sectional mean liquid holdup probes (S-CHOP) and the semi-supermultiple point-electrode probes (SS-PEP) in the wide range of superficial gas and liquid velocity, j{sub g} and j{sub {ell}}, and the liquid kinematic viscosities were {nu}{sub {ell}} = 1 x 10{sup {minus}6}, 10 x 10{sup {minus}6} and 20 x 10{sup {minus}6} m{sup 1}/s. The time-spatial maps of wave behavior and the interfacial profiles were presented. Close inspection of these results reveals that there also exist huge waves and disturbance waves in the higher liquid viscosity conditions. To clarify the characteristics of these waves, the wave-vein analysis and the cluster analysis by K-mean algorithm were applied. These methods distinguished huge wave and disturbance wave objectively. The appearance regions of liquid slug, huge wave, and disturbance wave for each liquid viscosity condition were presented and the effects of liquid viscosity on them were discussed. Furthermore, velocity, width and height of these waves were determined, and the effects of liquid viscosity on them were clarified.

  1. Adaptive optics fundus camera using a liquid crystal phase modulator

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Tatsuo; Nakazawa, Naoki; Bessho, Kenichiro; Kitaguchi, Yoshiyuki; Maeda, Naoyuki; Fujikado, Takashi; Mihashi, Toshifumi

    2008-05-01

    We have developed an adaptive optics (AO) fundus camera to obtain high resolution retinal images of eyes. We use a liquid crystal phase modulator to compensate the aberrations of the eye for better resolution and better contrast in the images. The liquid crystal phase modulator has a wider dynamic range to compensate aberrations than most mechanical deformable mirrors and its linear phase generation makes it easy to follow eye movements. The wavefront aberration was measured in real time with a sampling rate of 10 Hz and the closed loop system was operated at around 2 Hz. We developed software tools to align consecutively obtained images. From our experiments with three eyes, the aberrations of normal eyes were reduced to less than 0.1 μm (RMS) in less than three seconds by the liquid crystal phase modulator. We confirmed that this method was adequate for measuring eyes with large aberrations including keratoconic eyes. Finally, using the liquid crystal phase modulator, high resolution images of retinas could be obtained.

  2. A novel urea-functionalized surface-confined octadecylimidazolium ionic liquid silica stationary phase for reversed-phase liquid chromatography.

    PubMed

    Zhang, Mingliang; Tan, Ting; Li, Zhan; Gu, Tongnian; Chen, Jia; Qiu, Hongdeng

    2014-10-24

    One-pot synthesis of surface-confined ionic liquid functionalized silica spheres was proposed using N-(3-aminopropyl)imidazole, γ-isopropyltriethoxysilane and 1-bromooctadecane as starting materials. The surface modification of the silica spheres was successful with a high surface density of octadecylimidazolium, enabling the utilization of this new urea-functionalized ionic liquid-grafted silica material as stationary phase for high-performance liquid chromatography in reversed-phase mode. The long aliphatic chain combined with the multiple polar group embedded in the ligands imparted the new stationary phase fine selectivity towards PAH isomers and polar aromatics and higher affinity for phenolic compounds. The unique features of the new material, especially the effect of the urea group on the retention were elucidated by mathematic modeling. PMID:25249489

  3. Two-phase flow characteristics of liquid oxygen flow in low pressure liquid rocket engine

    NASA Astrophysics Data System (ADS)

    Cho, Namkyung; Kim, Seunghan; Kim, Youngmog; Jeong, Sangkwon; Jung, Jeheon

    2004-06-01

    In most cryogenic liquid rocket engines, liquid oxygen manifold and injector are not thermally insulated from room temperature environment for the purpose of reducing system complexity and weight. This feature of cryogenic liquid supply system results in the situation that liquid oxygen flow is vaporized especially in the vicinity of the manifold and the injector wall. The transient two-phase flow tendency is severe for low combustion pressure rocket engine without using turbo-pump. This paper focuses on the two-phase flow phenomena of liquid oxygen in low combustion pressure rocket engine. The KSR-III (Korea Sounding Rocket) engine test data is thoroughly analyzed to estimate the vapor fraction of liquid oxygen flow near the engine manifold and the injector. During the cold flow and the combustion tests of the KSR-III Engine, the static and dynamic pressures are measured at the engine inlet, the liquid oxygen manifold and the combustion chamber. The manifold outer wall and the inner wall temperatures are also measured. In this paper, we present the experimental investigation on the vapor generation, the vapor mass fraction, and the boiling characteristics of the liquid oxygen flow in the engine manifold and injector.

  4. Quantitative Chromatographic Determination of Dissolved Elemental Sulfur in the Non-aqueous Electrolyte for Lithium-Sulfur Batteries

    SciTech Connect

    Zheng, Dong; Yang, Xiao-Qing; Zhang, Xuran; Li, Chao; McKinnon, Meaghan E.; Sadok, Rachel G.; Qu, Deyu; Yu, Xiqian; Lee, Hung-Sui; Qu, Deyang

    2014-12-02

    A fast and reliable analytical method is reported for the quantitative determination of dissolved elemental sulfur in non-aqueous electrolytes for Li-S batteries. By using high performance liquid chromatography with a UV detector, the solubility of S in 12 different pure solvents and in 22 different electrolytes was determined. It was found that the solubility of elemental sulfur is dependent on the Lewis basicity, the polarity of solvents and the salt concentration in the electrolytes. In addition, the S content in the electrolyte recovered from a discharged Li-S battery was successfully determined by the proposed HPLC/UV method. Thus, the feasibility of the method to the online analysis for a Li-S battery is demonstrated. Interestingly, the S was found super-saturated in the electrolyte recovered from a discharged Li-S cell.

  5. Quantitative Chromatographic Determination of Dissolved Elemental Sulfur in the Non-aqueous Electrolyte for Lithium-Sulfur Batteries

    DOE PAGESBeta

    Zheng, Dong; Yang, Xiao-Qing; Zhang, Xuran; Li, Chao; McKinnon, Meaghan E.; Sadok, Rachel G.; Qu, Deyu; Yu, Xiqian; Lee, Hung-Sui; Qu, Deyang

    2014-12-02

    A fast and reliable analytical method is reported for the quantitative determination of dissolved elemental sulfur in non-aqueous electrolytes for Li-S batteries. By using high performance liquid chromatography with a UV detector, the solubility of S in 12 different pure solvents and in 22 different electrolytes was determined. It was found that the solubility of elemental sulfur is dependent on the Lewis basicity, the polarity of solvents and the salt concentration in the electrolytes. In addition, the S content in the electrolyte recovered from a discharged Li-S battery was successfully determined by the proposed HPLC/UV method. Thus, the feasibility ofmore » the method to the online analysis for a Li-S battery is demonstrated. Interestingly, the S was found super-saturated in the electrolyte recovered from a discharged Li-S cell.« less

  6. Intrinsic response of polymer liquid crystals in photochemical phase transition

    SciTech Connect

    Ikeda, Tomiki; Sasaki, Takeo; Kim, Haengboo )

    1991-01-24

    Time-resolved measurements were performed on the photochemically induced isothermal phase transition of polymer liquid crystals (PLC) with mesogenic side chains of phenyl benzoate (PAPB3) and cyanobiphenyl (PACB3) under conditions wherein the photochemical reaction of the doped photoresponsive molecule (4-butyl-4-{prime}-methoxyazobenzene, BMAB) was completed within {approximately} 10 ns, and the subsequent phase transition of the matrix PLC from nematic (N) to isotropic (I) state was followed by time-resolved measurements of the birefringence of the system. Formation of a sufficient amount of the cis isomer of BMAB with a single pulse of a laser lowered the N-I phase transition temperature of the mixture, inducing the N-I phase transition of PLCs isothermally in a time range of {approximately} 200 ms. This time range is comparable to that of low molecular weight liquid crystals, indicating that suppression in mobility of mesogens in PLCs does not affect significantly the thermodynamically controlled process.

  7. A model of liquid phase sintering by the homogenization

    NASA Astrophysics Data System (ADS)

    Pernin, Jean-Noël; Clementz, Philippe

    We study the first stage of liquid phase sintering, when the particles rearrangement due to capillary forces is over. We give the boundary value problem satisfied by the displacement field of points of the medium in the phase of elastic compression of solid particles, for given capillary forces acting as a density of external forces, by using the homogenization method and we characterize the mechanical behavior of this constrained medium from the material properties of each elementary components.

  8. Phase behavior and local structure of liquid crystalline polymers

    NASA Astrophysics Data System (ADS)

    Fynewever, Herb

    In this work we use a combination of theory and computer simulation to study the phase behavior of liquid crystalline polymers and the local structure of polymer melts. We review experimental and simulation evidence which shows that long and stiff molecules form orientationally ordered phases at packing fractions intermediate between the liquid and the solid. With the aid of a two-molecule simulation, we are able to apply Onsager's theory [Ann. N. Y. Acad. Sci. 51, 627 (1949)] for liquid crystal formation to flexible molecules without any additional approximations. Our results have a quantitative advantage over other theories in comparison with computer simulation data such as for the liquid-liquid crystal phase diagram. We also study the local structure of polymer melts using a two-molecule simulation to apply the density functional theories of Donley, Curro, and McCoy [J. Chem. Phys. 101 , 3205 (1994)1; and Yethiraj and Woodward [J. Chem. Phys 102 , 5499 (1995)]. The accuracy of these methods rivals that of integral equation theories in their predictions of local order. Further, the two-molecule simulation facilitates a more direct calculation of the equation of state via the monitoring of orientational correlations.

  9. On the phase-field modelling of a miscible liquid/liquid boundary.

    PubMed

    Xie, Ruilin; Vorobev, Anatoliy

    2016-02-15

    Mixing of miscible liquids is essential for numerous processes in industry and nature. Mixing, i.e. interpenetration of molecules through the liquid/liquid boundary, occurs via interfacial diffusion. Mixing can also involve externally or internally driven hydrodynamic flows, and can lead to deformation or disintegration of the liquid/liquid boundary. At the moment, the mixing dynamics remains poorly understood. The classical Fick's law, generally accepted for description of the diffusion process, does not explain the experimental observations, in particular, the recent experiments with dissolution of a liquid solute by a liquid solvent within a horizontal capillary (Stevar and Vorobev, 2012). We present the results of the numerical study aimed at development of an advanced model for the dissolution dynamics of liquid/liquid binary mixtures. The model is based on the phase-field (Cahn-Hilliard) approach that is used as a physics-based model for the thermo- and hydrodynamic evolution of binary mixtures. Within this approach, the diffusion flux is defined through the gradient of chemical potential, and, in particular, includes the effect of barodiffusion. The dynamic interfacial stresses at the miscible interface are also taken into account. The simulations showed that such an approach can accurately reproduce the shape of the solute/solvent boundary, and some aspects of the diffusion dynamics. Nevertheless, all experimentally-observed features of the diffusion motion of the solute/solvent boundary, were not reproduced. PMID:26609922

  10. Stretchable liquid-crystal blue-phase gels

    NASA Astrophysics Data System (ADS)

    Castles, F.; Morris, S. M.; Hung, J. M. C.; Qasim, M. M.; Wright, A. D.; Nosheen, S.; Choi, S. S.; Outram, B. I.; Elston, S. J.; Burgess, C.; Hill, L.; Wilkinson, T. D.; Coles, H. J.

    2014-08-01

    Liquid-crystalline polymers are materials of considerable scientific interest and technological value. An important subset of these materials exhibit rubber-like elasticity, combining the optical properties of liquid crystals with the mechanical properties of rubber. Moreover, they exhibit behaviour not seen in either type of material independently, and many of their properties depend crucially on the particular mesophase employed. Such stretchable liquid-crystalline polymers have previously been demonstrated in the nematic, chiral-nematic, and smectic mesophases. Here, we report the fabrication of a stretchable gel of blue phase I, which forms a self-assembled, three-dimensional photonic crystal that remains electro-optically switchable under a moderate applied voltage, and whose optical properties can be manipulated by an applied strain. We also find that, unlike its undistorted counterpart, a mechanically deformed blue phase exhibits a Pockels electro-optic effect, which sets out new theoretical challenges and possibilities for low-voltage electro-optic devices.

  11. Depositing spacing layers on magnetic film with liquid phase epitaxy

    NASA Technical Reports Server (NTRS)

    Moody, J. W.; Shaw, R. W.; Sanfort, R. M.

    1975-01-01

    Liquid phase epitaxy spacing layer is compatible with systems which are hard-bubble proofed by use of second magnetic garnet film as capping layer. Composite is superior in that: circuit fabrication time is reduced; adherence is superior; visibility is better; and, good match of thermal expansion coefficients is provided.

  12. Single-phase microemulsification of a complex light-nonaqueous-phase-liquid: Laboratory evaluation of several mixtures of surfactant/alcohol solutions

    SciTech Connect

    Rhue, R.D.; Rao, P.S.C.; Annable, M.D.

    1999-08-01

    A recent advance in conventional pump-and-treat technology for aquifer remediation involves the use of surfactant-alcohol mixtures that will form a clear, transparent, thermodynamically stable oil-in-water microemulsion on contact with a residual non-aqueous-phase-liquid (NAPL). An initial screening of 86 commercial-grade surfactants for aqueous solubility resulted in selection of 58 that were further tested in batch experiments to evaluate the capacity to solubilize a complex NAPL waste collected from a Superfund site (Operable Unit OU-1) at Hill AFB, UT. The selected group of 58 surfactants represented six classes of anionic, nine classes of nonionic, and one class of amphoteric surfactants. Batch studies on NAPL solubilization identified a number of surfactants suitable for use in the field demonstration phase of the project; a further criterion in surfactant selection was that the flushing solution had a viscosity <2 cp. The best surfactants among this group had HLB (hydrophilic-lipophilic balance) values between 12 and 13, and solubilized 10 to 20 g L{sup {minus}1} of the OU-1 NAPL when the surfactant concentration was 3%. Column tests using NAPL-coated glass beads showed that the more efficient surfactants could remove >90% of the NAPL after flushing with <10 pore volumes. Brij 97, an ethoxylated alcohol ether surfactant, showed a high capacity for solubilizing the OU-1 NAPL. In a column test using contaminated Hill AFB aquifer material, flushing with a mixture of 3% Brij 97 and 2.5% n-pentanol removed essentially all of the mass of nine target analytes in the NAPL after flushing with <10 pore volumes without mobilizing the NAPL or destabilizing aquifer colloids.

  13. pH Variance in Aerosols Undergoing Liquid-Liquid Phase Separation

    NASA Astrophysics Data System (ADS)

    Eddingsaas, N. C.; Dallemagne, M.; Huang, X.

    2014-12-01

    The water content of aerosols is largely governed by relative humidity (RH). As the relative humidity decreases, and thus the water content of aerosols, a number of processes occur including the shrinking of aerosols, the increase in concentration of components, and potentially the formation of liquid liquid phase separation (llps) due to the salting out of inorganic salts. The most ubiquitous salt in atmospheric aerosols is ammonium sulfate which results in many aerosols to be at least mildly acidic. However, during llps, the pH of the different phases is not necessarily the same. Many reactions that take place within atmospheric aerosols are acid catalyzed so a better understanding of the pH of the individual phases as well as the interface between the phases is important to understanding aerosol processing and aging. Through the use of pH sensitive dyes and confocal microscopy we have directly measured the pH of micron sized model aerosols during high RH where the aerosols are in a single phase, at intermediate while the aerosols are in llps, and low RH where the aerosols consist of one liquid phase and one solid phase. We will discuss the variation in RH during these different phase states in the presence and absence of excess sulfuric acid. We will also discuss how this variation in pH affects aging of aerosols.

  14. A novel non-aqueous aluminum sulfur battery

    NASA Astrophysics Data System (ADS)

    Cohn, Gil; Ma, Lin; Archer, Lynden A.

    2015-06-01

    An aluminum-sulfur battery comprised of a composite sulfur cathode, aluminum anode and an ionic liquid electrolyte of AlCl3/1-ethyl-3-methylimidazolium chloride is described. The electrochemical reduction of elemental sulfur has been studied in different molar ratios of the electrolyte, and aluminum tetrachloride ions have been identified at the electroactive ionic species. The Al/S battery exhibits a discharge voltage plateau of 1.1-1.2 V, with extremely high charge storage capacity of more than 1500 mAh g-1, relative to the mass of sulfur in the cathode. The energy density of the Al/S cell is estimated to be 1700 Wh kg-1 sulfur, which is competitive with the most attractive battery chemistries targeted for high-energy electrochemical storage. Characterization by means of SEM, XRD and XPS of the battery components reveal complete dissolution of sulfur-based discharge products to the electrolyte. The low cost, natural abundance and high volumetric energy density of both anode and cathode materials define a research path for new materials and cell designs for next-generation Al/S battery systems.

  15. Non aqueous electrolytes for lithium-sulfur dioxide batteries

    SciTech Connect

    Anantaraman, A.V.; Gardiner, C.L.

    1983-10-01

    Mixed organic solvent systems are of considerable interest for use in high energy density batteries. It has been observed that with a proper choice of solvents, one can achieve a drastic increase in cell performance-related properties such as dielectric constant, conductance, and viscosity. This paper presents a detailed investigation of the scope of mixed solvent systems with N-methyl pyrrolidinone (NMP) as the common solvent. Physical and thermodynamic properties such as density, viscosity, excess volume, and phase equilibria of mixed solvent systems with sulfur dioxide are studied, with a view to improving the performance and safety aspects of lithium/sulfur dioxide batteries.

  16. Liquid-liquid phase separation in heavy-metal fluoride glass

    SciTech Connect

    Suscavaye, M.J.; El-Bayoumi, O.H.

    1985-09-01

    The microstructure of heavy-metal fluoride glass of composition 28.5CdF/sub 2/. 5.0LiF.28.5AlF/sub 3/.38PbF/sub 2/ was investigated using scanning electron microscopy and energy-dispersive X-ray techniques. Liquid-liquid phase separation was observed in crucible-cooled glass samples. The volume fraction of the dispersed glass phase increased substantially as a result of heating the sample at 309/sup 0/C for 1 h.

  17. Liquid-gas phase transition in nuclear matter including strangeness

    SciTech Connect

    Wang, P.; Leinweber, D.B.; Williams, A.G.; Thomas, A.W.

    2004-11-01

    We apply the chiral SU(3) quark mean field model to study the properties of strange hadronic matter at finite temperature. The liquid-gas phase transition is studied as a function of the strangeness fraction. The pressure of the system cannot remain constant during the phase transition, since there are two independent conserved charges (baryon and strangeness number). In a range of temperatures around 15 MeV (precise values depending on the model used) the equation of state exhibits multiple bifurcates. The difference in the strangeness fraction f{sub s} between the liquid and gas phases is small when they coexist. The critical temperature of strange matter turns out to be a nontrivial function of the strangeness fraction.

  18. Anomalous properties and the liquid-liquid phase transition in gallium.

    PubMed

    Li, Renzhong; Sun, Gang; Xu, Limei

    2016-08-01

    A group of materials including water and silicon exhibit many anomalous behaviors, e.g., density anomaly and diffusivity anomaly (increase upon compression). These materials are hypothesized to have a liquid-liquid phase transition (LLPT) and the critical fluctuation in the vicinity of the liquid-liquid critical point is considered as the origin of different anomalies. Liquid gallium was also reported to have a LLPT, yet whether it shows similar water-like anomalies is not yet studied. Using molecular dynamics simulations on a modified embedded-atom model, we study the thermodynamic, dynamic, and structural properties of liquid gallium as well as its LLPT. We find that, similar to water-like materials predicted to have the LLPT, gallium also shows different anomalous behaviors (e.g., density anomaly, diffusivity anomaly, and structural anomaly). We also find that its thermodynamic and structural response functions are continuous and show maxima in the supercritical region, the loci of which asymptotically approach to the other and merge to the Widom line. These phenomena are consistent with the supercritical phenomenon in a category of materials with a liquid-liquid critical point, which could be common features in most materials with a LLPT. PMID:27497564

  19. Anomalous properties and the liquid-liquid phase transition in gallium

    NASA Astrophysics Data System (ADS)

    Li, Renzhong; Sun, Gang; Xu, Limei

    2016-08-01

    A group of materials including water and silicon exhibit many anomalous behaviors, e.g., density anomaly and diffusivity anomaly (increase upon compression). These materials are hypothesized to have a liquid-liquid phase transition (LLPT) and the critical fluctuation in the vicinity of the liquid-liquid critical point is considered as the origin of different anomalies. Liquid gallium was also reported to have a LLPT, yet whether it shows similar water-like anomalies is not yet studied. Using molecular dynamics simulations on a modified embedded-atom model, we study the thermodynamic, dynamic, and structural properties of liquid gallium as well as its LLPT. We find that, similar to water-like materials predicted to have the LLPT, gallium also shows different anomalous behaviors (e.g., density anomaly, diffusivity anomaly, and structural anomaly). We also find that its thermodynamic and structural response functions are continuous and show maxima in the supercritical region, the loci of which asymptotically approach to the other and merge to the Widom line. These phenomena are consistent with the supercritical phenomenon in a category of materials with a liquid-liquid critical point, which could be common features in most materials with a LLPT.

  20. Liquid-liquid phase separation of freely falling undercooled ternary Fe-Cu-Sn alloy

    PubMed Central

    Wang, W .L.; Wu, Y. H.; Li, L. H.; Zhai, W.; Zhang, X. M.; Wei, B.

    2015-01-01

    The active modulation and control of the liquid phase separation for high-temperature metallic systems are still challenging the development of advanced immiscible alloys. Here we present an attempt to manipulate the dynamic process of liquid-liquid phase separation for ternary Fe47.5Cu47.5Sn5 alloy. It was firstly dispersed into numerous droplets with 66 ~ 810 μm diameters and then highly undercooled and rapidly solidified under the containerless microgravity condition inside drop tube. 3-D phase field simulation was performed to explore the kinetic evolution of liquid phase separation. Through regulating the combined effects of undercooling level, phase separation time and Marangoni migration, three types of separation patterns were yielded: monotectic cell, core shell and dispersive structures. The two-layer core-shell morphology proved to be the most stable separation configuration owing to its lowest chemical potential. Whereas the monotectic cell and dispersive microstructures were both thermodynamically metastable transition states because of their highly active energy. The Sn solute partition profiles of Fe-rich core and Cu-rich shell in core-shell structures varied only slightly with cooling rate. PMID:26552711

  1. Liquid-liquid phase separation of freely falling undercooled ternary Fe-Cu-Sn alloy.

    PubMed

    Wang, W L; Wu, Y H; Li, L H; Zhai, W; Zhang, X M; Wei, B

    2015-01-01

    The active modulation and control of the liquid phase separation for high-temperature metallic systems are still challenging the development of advanced immiscible alloys. Here we present an attempt to manipulate the dynamic process of liquid-liquid phase separation for ternary Fe47.5Cu47.5Sn5 alloy. It was firstly dispersed into numerous droplets with 66 ~ 810 μm diameters and then highly undercooled and rapidly solidified under the containerless microgravity condition inside drop tube. 3-D phase field simulation was performed to explore the kinetic evolution of liquid phase separation. Through regulating the combined effects of undercooling level, phase separation time and Marangoni migration, three types of separation patterns were yielded: monotectic cell, core shell and dispersive structures. The two-layer core-shell morphology proved to be the most stable separation configuration owing to its lowest chemical potential. Whereas the monotectic cell and dispersive microstructures were both thermodynamically metastable transition states because of their highly active energy. The Sn solute partition profiles of Fe-rich core and Cu-rich shell in core-shell structures varied only slightly with cooling rate. PMID:26552711

  2. Liquid-liquid phase separation of freely falling undercooled ternary Fe-Cu-Sn alloy

    NASA Astrophysics Data System (ADS)

    Wang, W. L.; Wu, Y. H.; Li, L. H.; Zhai, W.; Zhang, X. M.; Wei, B.

    2015-11-01

    The active modulation and control of the liquid phase separation for high-temperature metallic systems are still challenging the development of advanced immiscible alloys. Here we present an attempt to manipulate the dynamic process of liquid-liquid phase separation for ternary Fe47.5Cu47.5Sn5 alloy. It was firstly dispersed into numerous droplets with 66 ~ 810 μm diameters and then highly undercooled and rapidly solidified under the containerless microgravity condition inside drop tube. 3-D phase field simulation was performed to explore the kinetic evolution of liquid phase separation. Through regulating the combined effects of undercooling level, phase separation time and Marangoni migration, three types of separation patterns were yielded: monotectic cell, core shell and dispersive structures. The two-layer core-shell morphology proved to be the most stable separation configuration owing to its lowest chemical potential. Whereas the monotectic cell and dispersive microstructures were both thermodynamically metastable transition states because of their highly active energy. The Sn solute partition profiles of Fe-rich core and Cu-rich shell in core-shell structures varied only slightly with cooling rate.

  3. Electrically tunable holographic polymer templated blue phase liquid crystal grating

    NASA Astrophysics Data System (ADS)

    He, Zheng-Hong; Chen, Chao-Ping; Zhu, Ji-Liang; Yuan, Ya-Chao; Li, Yan; Hu, Wei; Li, Xiao; Li, Hong-Jing; Lu, Jian-Gang; Su, Yi-Kai

    2015-06-01

    In this paper, we demonstrate an alternative approach to fabricating an electrically tunable holographic polymer templated blue phase liquid crystal grating. This grating is obtained by preforming a polymer template comprised of periodic fringes, and then refilling it with a blue phase liquid crystal. Compared with conventional holographic polymer dispersed liquid crystal gratings, our grating can remarkably reduce its switching voltage from 200 V to 43 V while maintaining a sub-millisecond response time. The holographic polymer templated blue phase liquid crystal (HPTBPLC) grating is free from electrode patterning, thus leading to a lower cost and more flexible applications. Project supported by the National Basic Research Program of China (Grant No. 2013CB328804), the National Natural Science Foundation of China (Grant No. 61307028), the Funds from the Science and Technology Commission of Shanghai Municipality (Grant Nos. 11JC1405300, 13ZR1420000, and 14ZR1422300), and the Fundamental Research Funds for the Central Universities, China (Grant No. XDJK 2011C047).

  4. Gravitational contributions to microstructural coarsening in liquid phase sintering

    NASA Technical Reports Server (NTRS)

    Kipphut, C. M.; Kishi, T.; Bose, A.; German, R. M.

    1987-01-01

    Preliminary experiments for determining the role of gravity in liquid phase sintering have been carried out. Tungsten heavy alloys were selected for this investigation because of the large density difference between solid and liquid, extensive interest in the alloys and considerable data on these alloys. By identifying and isolating the role that gravity plays in shape distortion and microstructural coarsening, further insight into the mechanisms of coarsening kinetics may be realized. Improvements in mechanical properties, shape complexity, and dimensional stability may be realized in the future from low gravity sintering.

  5. 4He glass phase: A model for liquid elements

    NASA Astrophysics Data System (ADS)

    Tournier, Robert F.; Bossy, Jacques

    2016-08-01

    The specific heat of liquid helium confined under pressure in nanoporous material and the formation, in these conditions, of a glass phase accompanied by latent heat are known. These properties are in good agreement with a recent model predicting, in liquid elements, the formation of ultrastable glass having universal thermodynamic properties. The third law of thermodynamics involves that the specific heat decreases at low temperatures and consequently the effective transition temperature of the glass increases up to the temperature where the frozen enthalpy becomes equal to the predicted value. The glass residual entropy is about 23.6% of the melting entropy.

  6. String theory, quantum phase transitions, and the emergent Fermi liquid.

    PubMed

    Cubrović, Mihailo; Zaanen, Jan; Schalm, Koenraad

    2009-07-24

    A central problem in quantum condensed matter physics is the critical theory governing the zero-temperature quantum phase transition between strongly renormalized Fermi liquids as found in heavy fermion intermetallics and possibly in high-critical temperature superconductors. We found that the mathematics of string theory is capable of describing such fermionic quantum critical states. Using the anti-de Sitter/conformal field theory correspondence to relate fermionic quantum critical fields to a gravitational problem, we computed the spectral functions of fermions in the field theory. By increasing the fermion density away from the relativistic quantum critical point, a state emerges with all the features of the Fermi liquid. PMID:19556462

  7. Thermal Vibrational Convection in a Two-phase Stratified Liquid

    NASA Technical Reports Server (NTRS)

    Chang, Qingming; Alexander, J. Iwan D.

    2007-01-01

    The response of a two-phase stratified liquid system subject to a vibration parallel to an imposed temperature gradient is analyzed using a hybrid thermal lattice Boltzmann method (HTLB). The vibrations considered correspond to sinusoidal translations of a rigid cavity at a fixed frequency. The layers are thermally and mechanically coupled. Interaction between gravity-induced and vibration-induced thermal convection is studied. The ability of applied vibration to enhance the flow, heat transfer and interface distortion is investigated. For the range of conditions investigated, the results reveal that the effect of vibrational Rayleigh number and vibrational frequency on a two-phase stratified fluid system is much different than that for a single-phase fluid system. Comparisons of the response of a two-phase stratified fluid system with a single-phase fluid system are discussed.

  8. Superfluid helium 2 liquid-vapor phase separation: Technology assessment

    NASA Technical Reports Server (NTRS)

    Lee, J. M.

    1984-01-01

    A literature survey of helium 2 liquid vapor phase separation is presented. Currently, two types of He 2 phase separators are being investigated: porous, sintered metal plugs and the active phase separator. The permeability K(P) shows consistency in porous plug geometric characterization. Both the heat and mass fluxes increase with K(P). Downstream pressure regulation to adjust for varying heat loads and both temperatures is possible. For large dynamic heat loads, the active phase separator shows a maximum heat rejection rate of up to 2 W and bath temperature stability of 0.1 mK. Porous plug phase separation performance should be investigated for application to SIRTF and, in particular, that plugs of from 10 to the minus ninth square centimeters to 10 to the minus eighth square centimeters in conjunction with downstream pressure regulation be studied.

  9. Elastic response and phase behavior in binary liquid crystal mixtures.

    PubMed

    Sidky, Hythem; Whitmer, Jonathan K

    2016-05-11

    Utilizing density-of-states simulations, we perform a full mapping of the phase behavior and elastic responses of binary liquid crystalline mixtures represented by the multicomponent Lebwohl-Lasher model. Our techniques are able to characterize the complete phase diagram, including nematic-nematic phase separation predicted by mean-field theories, but previously not observed in simulations. Mapping this phase diagram permits detailed study of elastic properties across the miscible nematic region. Importantly, we observe for the first time local phase separation and disordering driven by the application of small linear perturbations near the transition temperature and more significantly through nonlinear stresses. These findings are of key importance in systems of blended nematics which contain particulate inclusions, or are otherwise confined. PMID:27093188

  10. Induced smectic phases of stoichiometric liquid crystal mixtures.

    PubMed

    Sugisawa, Shin-Ya; Tabe, Yuka

    2016-03-16

    We revealed the detailed structures of induced smectic liquid crystal (LC) phases composed of a binary mixture of charge-transfer (CT) LC substances. Although neither of the constituents had highly ordered smectic phases, the mixture exhibited smectic-E (SmE) or smectic-B (SmB) phases when mixed at ratios of 1 : 1 and 2 : 3, respectively. The results of polarized optical microscopy, differential scanning calorimetry, X-ray diffraction, and infrared spectroscopy indicated that the induced smectic phases were stabilized by an exquisite balance between the CT interactions, dipolar interactions, and excluded volume effects. We proposed a possible model for the molecular arrangements in the SmE and SmB phases, which consistently explained the experimental results including the stoichiometric ratios. PMID:26898174