Sample records for liquid-phase activity coefficients

  1. Liquid-phase Mutual Diffusion Coefficients for Heavy Oil + Light Hydrocarbon Mixtures

    Microsoft Academic Search

    X. Zhang; J. M. Shaw

    2007-01-01

    Liquid-phase mutual diffusion coefficients are a key parameter in reservoir simulation models related to both primary production and envisioned secondary recovery processes for heavy oil and bitumen. The measurement of liquid-phase mutual diffusion coefficients in bitumen and heavy oil + light hydrocarbon or gas mixtures present numerous experimental and data analysis challenges due to the viscosity and opacity of the

  2. Liquid phase deposition of hemoglobin/SDS/TiO2 hybrid film preserving photoelectrochemical activity.

    PubMed

    Wang, Rui; Zhang, Jingdong; Hu, Yonggang

    2011-04-01

    This work demonstrates that liquid phase deposition (LPD) technique provides a novel approach to the immobilization of hemoglobin (Hb) in TiO(2) film for studying the direct electron transfer of Hb. Using the LPD process, a hybrid film composed of Hb, TiO(2) and sodium dodecylsulfonate (SDS) is successfully prepared on the electrode surface. The surface morphology of as-deposited Hb/SDS/TiO(2) film shows a flower-like structure. The cyclic voltammetric measurement indicates that the LPD hybrid film facilitates the electron transfer of Hb, which yields a pair of redox peaks prior to the characteristic voltammetric peaks of TiO(2). Due to the electrocatalytic activity of Hb towards H(2)O(2), the Hb/SDS/TiO(2) hybrid LPD film can be utilized as an H(2)O(2) sensor, showing a sensitive response linearly proportional to the concentration of H(2)O(2) in the range of 5.0×10(-7)-4.0×10(-5) mol/L. At the same time, the Hb/SDS/TiO(2) hybrid film preserves the photoelectrochemical activity of TiO(2). The photovoltaic effect on the electrochemical behavior of Hb/SDS/TiO(2) film is observed after long-time UV irradiation on the film, which could improve the calibration sensitivity for H(2)O(2). PMID:21334986

  3. Carbon nanofibers supported nickel catalyst for liquid phase hydrogenation of benzene with high activity and selectivity

    Microsoft Academic Search

    Pingle Liu; Huan Xie; Shirong Tan; Kuiyi You; Nailiang Wang; He’an Luo

    2009-01-01

    Carbon nanofibers (CNFs) prepared by catalytic decomposition of ethylene are used as support for nickel. The CNF support displays\\u000a a mean diameter of 50–60 nm, lengths up to several tens of micrometers, as highlighted by TEM. The nickel particles have a\\u000a size distribution from 10 to 20 nm of diameter. This novel Ni\\/CNFs catalyst displays good catalytic properties in liquid phase\\u000a hydrogenation

  4. 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)

  5. Approach to In- Situ Producing Reinforcing Phase Within an Active-Transient Liquid Phase Bond Seam for Aluminum Matrix Composite

    NASA Astrophysics Data System (ADS)

    Zhang, Guifeng; Liao, Xianjin; Chen, Bo; Zhang, Linjie; Zhang, Jianxun

    2015-06-01

    To optimize the braze composition design route for aluminum matrix composite, the feasibility of in situ producing reinforcing phase within the transient liquid phase bond seam matrix, by adding active melting point increaser (MPI, e.g., Ti) together with general melting point depressant (MPD, e.g., Cu) into the interlayer, was demonstrated. For SiC p /A356 composite, by comparing the wettability, joint microstructure, joint shear strength, and fracture path for the developed Al-19Cu-1Ti, Al-19Cu, Al-33Cu-1Ti, Al-33Cu (wt pct), and commercial Cu foils as interlayer, the feasibility of in situ producing reinforcing phase within the bond seam by adding Ti was demonstrated. Especially for Al-19Cu-1Ti active braze, small and dispersed ternary aluminide of Al-Si-Ti phase was obtained within the bond seam as in situ reinforcement, leading to a favorable fracture path within SiC p /A356, not along the initial interface or within the bond seam. For the formation mechanism of the in situ reinforcing phase of MPI-containing intermetallic compound within the bond seam, a model of repeating concentration-precipitation-termination-engulfment during isothermal solidification is proposed.

  6. Liquid-phase adsorption of dyes and phenols using pinewood-based activated carbons

    Microsoft Academic Search

    Ru-Ling Tseng; Feng-Chin Wu; Ruey-Shin Juang

    2003-01-01

    Physical properties of activated carbons prepared from pinewood at different activation times (0.5, 1.5, 2.7, and 4.0 h) in steam at 900°C were studied. The adsorption equilibria and kinetics of three dyes and three phenols (phenol, 3-chlorophenol, and o-cresol) from aqueous solutions on such carbons were then examined at 30°C. The adsorption isotherms of phenols could be well fitted by

  7. Chromium removal from flocculation effluent of liquid-phase oil-based drill-cuttings using powdered activated carbon

    Microsoft Academic Search

    M. J. Ayotamuno; R. N. Okparanma; S. O. T. Ogaji; S. D. Probert

    2007-01-01

    The practice of injecting the flocculation effluent of liquid-phase oil-based drill-cuttings (LP-OBDCs) into the ground is a popular current disposal-option for this type of drilling waste in Nigeria. Unfortunately, this practice leads to environmental degradation because this flocculation effluent contains high concentrations of chromium (Cr6+), which is a heavy-metal pollutant. Consequently, it is recommended that the flocculation effluent be treated

  8. Analysis of the structural interaction of electrically active heterogeneous finely dispersed systems at the interfaces between the solid and liquid phases

    NASA Astrophysics Data System (ADS)

    Shcherbachenko, L. A.; Maksimova, N. T.; Baryshnikov, S. S.; Karnakov, V. A.; Marchuk, S. D.; Ezhova, L. I.

    2011-07-01

    Strong electrical forces have been revealed in electrically active heterogeneous finely dispersed systems at the interfaces between the solid and liquid phases. It has been established that these forces give rise to gradients of the potential of an internal self-electric field that can provide circulation of electric currents in the systems under investigation. It has been found that, in these systems, there arises a double electric layer that represents a new structuring phase, which is characteristic of electrically active systems only. The mechanism of formation of a double electric layer includes electrocontact interaction between the surfaces of two heterogeneous liquid and solid polar dielectrics.

  9. Preparation of activated carbons from unburnt coal in bottom ash with KOH activation for liquid-phase adsorption

    Microsoft Academic Search

    Feng-Chin Wu; Pin-Hsueh Wu; Ru-Ling Tseng; Ruey-Shin Juang

    2010-01-01

    In this work, unburnt coal (UC) in bottom ash from coal-fired power plants was soaked in KOH solution and activated for 1 h at 780 °C. The yield of activated carbons varied from 47.8 to 54.8% when the KOH\\/UC weight ratio changed from 2 to 4. Pore properties of these activated carbons including the BET surface area, pore volume, pore size distribution,

  10. Liquid-phase growth of platinum nanoparticles on molybdenum trioxide nanosheets: an enhanced catalyst with intrinsic peroxidase-like catalytic activity

    NASA Astrophysics Data System (ADS)

    Wang, Yixian; Zhang, Xiao; Luo, Zhimin; Huang, Xiao; Tan, Chaoliang; Li, Hai; Zheng, Bing; Li, Bing; Huang, Ying; Yang, Jian; Zong, Yun; Ying, Yibin; Zhang, Hua

    2014-10-01

    A facile method for the synthesis of metal nanostructure-decorated two-dimensional (2D) semiconductor nanosheets was developed. The solution-processable molybdenum trioxide (MoO3) nanosheet was used as a template for direct liquid-phase growth of platinum nanoparticles (Pt NPs) under ambient conditions. Results show that the Pt NPs with sizes of 1-3 nm were uniformly grown on the MoO3 surface. Importantly, the Pt-MoO3 hybrid nanomaterial exhibits an enhanced peroxidase-like catalytic activity compared to the MoO3 nanosheet, Pt NPs, and their physical mixture under the same conditions. As a proof-of-concept application, the Pt-MoO3 hybrid nanomaterial was used as a high-efficiency peroxidase-mimic for ultrasensitive colorimetric detection of glucose in serum samples. This work provides a promising strategy for design and development of biomimetic catalysts by smart assembly of different dimensional nanomaterials.A facile method for the synthesis of metal nanostructure-decorated two-dimensional (2D) semiconductor nanosheets was developed. The solution-processable molybdenum trioxide (MoO3) nanosheet was used as a template for direct liquid-phase growth of platinum nanoparticles (Pt NPs) under ambient conditions. Results show that the Pt NPs with sizes of 1-3 nm were uniformly grown on the MoO3 surface. Importantly, the Pt-MoO3 hybrid nanomaterial exhibits an enhanced peroxidase-like catalytic activity compared to the MoO3 nanosheet, Pt NPs, and their physical mixture under the same conditions. As a proof-of-concept application, the Pt-MoO3 hybrid nanomaterial was used as a high-efficiency peroxidase-mimic for ultrasensitive colorimetric detection of glucose in serum samples. This work provides a promising strategy for design and development of biomimetic catalysts by smart assembly of different dimensional nanomaterials. Electronic supplementary information (ESI) available: Experimental details, Fig. S1-S9, and Tables S1 and S2 as mentioned in the text. See DOI: 10.1039/c4nr04115a

  11. Activation energy of liquid-phase hydrogenation of 1-hexyne over transition metals at elevated hydrogen pressures

    SciTech Connect

    Sokol'skii, D.V.; Ualikhanova, A.

    1983-02-20

    The apparent activation energies of hydrogenation of 1-hexyne in presence of transition metals are in the range 16-51 kJ/mole and depend on the nature of the metal, the support, and the solvent. The activation energies of hydrogenation of 1-hexyne in presence of transition elements are not altered significantly when the reaction order with respect to hydrogen changes from one to zero.

  12. 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.

  13. Composition of Coexisting Liquid Phases Determined by Rayleigh Interferometry

    E-print Network

    Annunziata, Onofrio

    polymers [4]. Thus, we utilize Rayleigh interfer- ometry for determination of the PEG and PVA compositionsComposition of Coexisting Liquid Phases Determined by Rayleigh Interferometry Alessandro Molisso for the determination of composition of ternary aqueous mixtures. The effect of cross-term diffusion coefficients

  14. Liquid phase chromatography on microchips.

    PubMed

    Kutter, Jörg P

    2012-01-20

    Over the past twenty years, the field of microfluidics has emerged providing one of the main enabling technologies to realize miniaturized chemical analysis systems, often referred to as micro-Total Analysis Systems (uTAS), or, more generally, Lab-on-a-Chip Systems (LOC) [1,2]. While microfluidics was driven forward a lot from the engineering side, especially with respect to ink jet and dispensing technology, the initial push and interest from the analytical chemistry community was through the desire to develop miniaturized sensors, detectors, and, very early on, separation systems. The initial almost explosive development of, in particular, chromatographic separation systems on microchips, has, however, slowed down in recent years. This review takes a closer, critical look at how liquid phase chromatography has been implemented in miniaturized formats over the past several years, what is important to keep in mind when developing or working with separations in a miniaturized format, and what challenges and pitfalls remain. PMID:22071425

  15. Overview of reactors for liquid phase Fischer–Tropsch synthesis

    Microsoft Academic Search

    Burtron H. Davis

    2002-01-01

    The following overview is divided roughly into three sections. The first section covers the period from the late 1920s when the first liquid phase synthesis was first conducted until about 1960 when the interest in Fischer–Tropsch synthesis (FTS) declined because of the renewed view of an abundance of petroleum at a low price. The second period includes the activity that

  16. Transient liquid phase ceramic bonding

    DOEpatents

    Glaeser, Andreas M. (Berkeley, CA)

    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.

  17. Infinite dilution activity coefficients in chemical, environmental and biochemical engineering

    Microsoft Academic Search

    S. I. Sandler

    1996-01-01

    Here we briefly review several methods by which infinite dilution activity coefficients can be obtained, and then consider how such data can be used. In particular, we examine the accuracy of predictions of vapor-liquid equilibria over the complete concentration range, and over a range of temperatures based on infinite dilution activity coefficient data at a single temperature. Next, we review

  18. 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.

  19. Liquid-phase sintering of ceramics

    SciTech Connect

    Marion, J.E.; Hsueh, C.H.; Evans, A.G.

    1987-10-01

    Expressions for the sintering rate in liquid-phase sintering are derived for coupled-interface dissolution and liquid-phase diffusion. The analysis reveals the important role of stress gradients in the grain boundary phase and also shows that such gradients cannot be supplied by liquid-phase flow. Stress-supporting structure in the grain boundary phase is thus implied. The probable existence of such structure is revealed by diffuse dark-field scattering studies, using transmission electron microscopy, on partially sintered alumina/anorthite bodies.

  20. Liquid phase sintering in microgravity

    NASA Astrophysics Data System (ADS)

    Smith, J.; Lundquist, C.; Riley, M.; Robinson, R.

    Liquid Phase Sintering (LPS) experiments have been conducted on four suborbital rockets, six Space Shuttle missions and two missions to the Mir Space Station by our research group. These missions began in 1989, spanning over 10 years. This paper will overview the many separate and interesting research and technical challenges faced in these missions and review the many published models developed to date by our group. The principle finding is that microgravity materials made using typical liquid phase sintering approaches are inferior to those made on earth. This results from pressing the green, presintered compact from their constituent powders, Fe and Co base materials with a Cu additive phase, producing composites that have solid volume fractions of 70-80%, with the balance either vacuum filled pores or entrapped gas. During LPS, the compact is processed above the melting point of the additive phase, producing a three-phase system. On earth, the entrapped gas is rapidly eliminated, and particle rearrangement is principally by buoyancy driven convection. In microgravity, this is not the case. In microgravity systems, all three phases exist concurrently, and the gas phase is not eliminated by buoyancy driven convection. Instead, the gas phase alters the free energy of the composite producing a variety of transport processes not typically seen in the earth based experiments, a positive result. Microgravity experiments slow down the typically fast acting rearrangement phase, permitting detailed study of the rapid processes taking place on earth in the first few seconds to minutes of LPS. Results from space processing have lead to a reconsideration of unit gravity models during the rearrangement stage. It has lead to a new model to explain the initiation of pore metamorphosis in LPS sample processed in microgravity, where pore breakup, coalescence and filling were found. Diffusion controlled grain growth in mutually soluble alloy phase systems, such as Co-Cu, was observed for the first time and a shrinking core model developed that successfully modeled this aspect of grain growth. In the absence of gravity, the grain coarsening model should follow the Lifshitz-Slyozov and Wagner (LSW) theory. Our extensive analysis of over 200 samples has shown that, contrary to expectation, there was an enhancement in particle coarsening with a decrease in the volume fraction of solid. The agglomerated microstructures exhibited a higher grain growth constant consistent with their higher 3D coordination number. Though buoyancy driven convection is eliminated, Brownian motion is not and becomes dominate in microgravity. This driving force leads to agglomeration and the need to use the Lifshitz-Slyozov Encounter Modified (LSEM) model to correctly model the results. Many papers on these phenomena h ve appeared in the literature and will be summarized anda presented along with a discussion of systems and subsystems needed to successfully conduct high temperature microgravity research on the fundamental mechanisms associated with LPS.

  1. Structure analysis of turbulent liquid phase by POD and LSE techniques

    SciTech Connect

    Munir, S., E-mail: shahzad-munir@comsats.edu.pk; Muthuvalu, M. S.; Siddiqui, M. I. [Department of Fundamental and Applied Science, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak Darul Ridzuan (Malaysia); Heikal, M. R., E-mail: morgan.heikal@petronas.com.my; Aziz, A. Rashid A., E-mail: morgan.heikal@petronas.com.my [Department of Mechanical Engineering, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak Darul Ridzuan (Malaysia)

    2014-10-24

    In this paper, vortical structures and turbulence characteristics of liquid phase in both single liquid phase and two-phase slug flow in pipes were studied. Two dimensional velocity vector fields of liquid phase were obtained by Particle image velocimetry (PIV). Two cases were considered one single phase liquid flow at 80 l/m and second slug flow by introducing gas at 60 l/m while keeping liquid flow rate same. Proper orthogonal decomposition (POD) and Linear stochastic estimation techniques were used for the extraction of coherent structures and analysis of turbulence in liquid phase for both cases. POD has successfully revealed large energy containing structures. The time dependent POD spatial mode coefficients oscillate with high frequency for high mode numbers. The energy distribution of spatial modes was also achieved. LSE has pointed out the coherent structured for both cases and the reconstructed velocity fields are in well agreement with the instantaneous velocity fields.

  2. Structure analysis of turbulent liquid phase by POD and LSE techniques

    NASA Astrophysics Data System (ADS)

    Munir, S.; Heikal, M. R.; Aziz, A. Rashid A.; Muthuvalu, M. S.; Siddiqui, M. I.

    2014-10-01

    In this paper, vortical structures and turbulence characteristics of liquid phase in both single liquid phase and two-phase slug flow in pipes were studied. Two dimensional velocity vector fields of liquid phase were obtained by Particle image velocimetry (PIV). Two cases were considered one single phase liquid flow at 80 l/m and second slug flow by introducing gas at 60 l/m while keeping liquid flow rate same. Proper orthogonal decomposition (POD) and Linear stochastic estimation techniques were used for the extraction of coherent structures and analysis of turbulence in liquid phase for both cases. POD has successfully revealed large energy containing structures. The time dependent POD spatial mode coefficients oscillate with high frequency for high mode numbers. The energy distribution of spatial modes was also achieved. LSE has pointed out the coherent structured for both cases and the reconstructed velocity fields are in well agreement with the instantaneous velocity fields.

  3. Liquid-phase oxidation of propylene to propylene glycol acetates over Pd\\/C and Pt?Pd\\/C: Effect of platinum on catalyst activity and metal dispersity

    Microsoft Academic Search

    A. V. Karandin; E. V. Gusevskaya; V. A. Likholobov; E. M. Moroz; V. I. Zaikovskii

    1992-01-01

    Kinetics of oxidation of propylene to propylene glycol and its acetates in acetic acid solutions of lithium nitrate over Pd\\/C and Pd?Pt\\/C catalysts has been studied. Catalysts were investigated using X-ray phase analysis and electron microscopy. Platinum introduction into catalyst increases the metal dispersity and the catalyst stability but produces no effect on the nature of surface sites active in

  4. 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.

  5. 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.

  6. Binary Solid-Liquid Phase Equilibria

    ERIC Educational Resources Information Center

    Ellison, Herbert R.

    1978-01-01

    Indicates some of the information that may be obtained from a binary solid-liquid phase equilibria experiment and a method to write a computer program that will plot an ideal phase diagram to which the experimental results may be compared. (Author/CP)

  7. CONTINENTAL LIQUID-PHASE STRATUS CLOUDS AT SGP: METEOROLOGICAL INFLUENCES AND RELATIONSHIP TO ADIABACITY

    E-print Network

    CONTINENTAL LIQUID-PHASE STRATUS CLOUDS AT SGP: METEOROLOGICAL INFLUENCES AND RELATIONSHIP clouds observed over SGP appear to be substantially influenced by micrometeorological conditions of aerosol light scattering coefficient with cloud-drop effective radius [Kim et al., JGR, 2003], although

  8. Infinite dilution activity coefficient measurements by inert gas stripping method

    Microsoft Academic Search

    Piia Haimi; Petri Uusi-Kyyny; Juha-Pekka Pokki; Juhani Aittamaa; Kari I. Keskinen

    2006-01-01

    The values of activity coefficients at infinite dilution (??) are of especially significance in the reliable design of thermal separation processes producing pure compounds. The ?? has been determined for six branched ethers and four sulfur compounds in water using the dilutor technique. The measurements were carried out in the temperature range from 288 to 333K.

  9. Infinite dilution activity coefficients and Henry's law coefficients of some priority water pollutants determined by a relative gas chromatographic method

    SciTech Connect

    Tse, G.; Orbey, H.; Sandler, S.I. (Univ. of Delaware, Newark, DE (United States))

    1992-10-01

    A simple, fast relative measurement method based on gas chromatography developed recently has been used to determine the infinite dilution activity coefficients and Henry's law coefficients in water of some priority pollutants. The authors show that this simple method can be used to obtain accurate data quite rapidly, which is especially valuable for screening studies. Further, the infinite dilution activity coefficient and Henry's law coefficient data reported here can be useful for directly estimating environmentally important properties such as solubilities in water, multimedia partitioning, and octanol-water partition coefficients. 8 refs., 1 tab.

  10. LIQUID PHASE SINTERED METAL MATRIX COMPOSITE MATERIALS

    Microsoft Academic Search

    S. J. Yankee; G. M. Janowski; B. J. Pletka

    1990-01-01

    Iron-base and aluminum-base composite materials reinforced with various ceramic particulates have been fabricated via powder metallurgy and liquid phase sintering. The advantage of this manufacturing route is that conventional powder metallurgy processing equipment can be used to fabricate metal matrix\\/ceramic composites. Furthermore, this approach makes it possible to manufacture these composites to near-net-shape. A number of matrix\\/ceramic combinations have been

  11. Predicting liquid-phase thermodynamic properties using COSMO-SAC

    NASA Astrophysics Data System (ADS)

    Burnett, Russell I.

    Predicting thermodynamic properties of liquids remains a significant challenge in both academia and industry. This is because molecules in the liquid phase are relatively close together but are not arranged in an ordered structure. The COSMO-SAC model uses quantum and statistical mechanics to predict the thermodynamic properties of liquids. In this thesis, a variety of efforts have been made to improve the accuracy of this model. The most successful of these involves the inclusion of dispersion interactions in mixture calculations, which reduces the average prediction error for activity coefficients by over 30%. It has also been demonstrated that the misfit energy—the traditional interaction energy used in all known COSMO-based models—is limited in its ability to model intermolecular interactions. A variety of attempts to improve the electrostatics of the model have been made, but these have had little effect on the overall accuracy. These include use of an expanded hydrogen bonding description, use of an alternate molecular surface construction method, and incorporation of three-dimensional considerations. These results, coupled with the observed improvement obtained from including dispersion interactions, suggest that the greatest weakness in the model is the handling of electrodynamics (how molecules polarize one another), and that future efforts to improve the model should target this area. In addition, the model has been parameterized for the ADF density functional software package, thus making it available to a wider audience. Results are approximately equivalent to those obtained with DMol3, the only package for which a published parameterization was previously available. Of significance, the ADF implementation allows one of the adjustable model parameters to be eliminated. Also, a correlation was found between experimental liquid volumes and the quantum-based molecular volumes employed in COSMO-SAC. This eliminates the need to provide experimental volumes to the model. Finally, a Windows-based graphical user interface for COSMO-SAC has been developed. This expands the availability of the model to anyone with only a general familiarity with thermodynamics. Without this, use is restricted to those with an in-depth knowledge of quantum mechanics, statistical mechanics and computer programming.

  12. Characterization of methylene blue\\/TiO 2 hybrid thin films prepared by the liquid phase deposition (LPD) method: Application for fabrication of light-activated colorimetric oxygen indicators

    Microsoft Academic Search

    David Gutiérrez-Tauste; Xavier Domènech; Nieves Casañ-Pastor; José A. Ayllón

    2007-01-01

    Methylene blue (MB)\\/TiO2 hybrid nanocomposite material has been successfully deposited on both bare glass and indium tin oxide (ITO) covered glass by the liquid phase deposition (LPD) technique. LPD method is applied to one-step hybrid dye\\/TiO2 deposition. An optimized amount of MB is added to the fluoride titania precursor aqueous solution in order to entrap this dye within the growing

  13. TheLiquidPhase: Countercurrent Chromatography

    NSDL National Science Digital Library

    TheLiquidPhase is a community portal, or wiki, dedicated to the proliferation of knowledge and good technique in countercurrent chromatography (CCC). It has been organized to help prospective users of CCC learn about its potential and to provide a virtual meeting place for discussions among experienced users of the technique. There are pages explaining CCC, how to get started, and describing a typical setup; sections devoted to solvent systems, modes of operation, and CCC chromatograms; an undergraduate chemistry lab experiment using CCC; lists of manufacturers and distributors; a bibliography, and an alphabetical index.

  14. THE ACTIVITY COEFFICIENTS OF ALKALI METAL NITRATES AND PERCHLORATES IN DILUTE AQUEOUS SOLUTIONS AT 25 FROM DIFFUSION COEFFICIENTS

    Microsoft Academic Search

    H. S. Harned; J. A. Shropshire

    1958-01-01

    The diffusion coefficients of lithium and cesium nitrates have been ; measured at 25 deg over a concentration range from 0.003 to 0.015 molar. From ; these data, the activity coefficients of these electrolytes have been compated at ; low concentrations. Similar calculations have been carried cat for lithium and ; potassium perchlorates and potassium nitrate solutions and the results

  15. Activity and Activity Coefficient of Iron Oxides in the Liquid FeO-Fe2O3-CaO-SiO2 Slag Systems at Intermediate Oxygen Partial Pressures

    NASA Astrophysics Data System (ADS)

    Henao, Hector M.; Itagaki, Kimio

    2007-10-01

    At present, there is a scarcity of data on the activities of iron oxides in the FeO-Fe2O3-CaO-SiO2 slag system at intermediate oxygen partial pressures and temperatures relevant to sulfide smelting and nonferrous metallurgy. The present study provides relevant data at temperatures between 1573 and 1673 K and partial pressures of oxygen between 10-9 and 10-4 atm. The experiments were carried out by equilibrating the slag in a CO-CO2 gas mixture in a platinum crucible, after which the phases of all the experimental samples, including the platinum foil, were analyzed by electron probe microanalysis (EPMA). Where only liquid phase or liquid phase and tridymite (SiO2) were observed, wet chemical analysis was used to determine the ratio of (mass pct Fe2+)/(mass pct Fe3+). Activity and activity coefficients for FeO (liquid) and FeO1.33 (solid) were calculated. Tendencies of the effect of the (CaO/SiO2) ratio, temperature, and oxygen partial pressure on these thermochemical quantities are discussed in this article.

  16. Commercial-Scale Demonstration of the Liquid Phase Methanol (LPMEOH(TM)) Process

    SciTech Connect

    None

    1997-06-30

    The Liquid Phase Methanol (LPMEOHTM) Demonstration Project at Kingsport, Tennessee, is a $213.7 million cooperative agreement between the U.S. Department of Energy (DOE) and Air Products Liquid Phase Conversion Company, L.P. (the Partnership). Air Products and Chemicals, Inc. (Air Products) and Eastman Chemical Company (Eastman) formed the Partnership to execute the Demonstration Project. The LPMEOIYM Process Demonstration Unit was built at a site located at the Eastman complex in Kingsport. During this quarter, comments from the DOE on the Topical Report "Economic Analysis - LPMEOHTM Process as an Add-on to IGCC for Coproduction" were received. A recommendation to continue with design verification testing for the coproduction of dimethyl ether (DIME) and methanol was made. DME design verification testing studies show the liquid phase DME (LPDME) process will have a significant economic advantage for the coproduction of DME for local markets. An LPDME catalyst system with reasonable long-term activity and stability is being developed. A recommendation document summarizing catalyst targets, experimental results, and the corresponding economics for a commercially successful LPDME catalyst was issued on 30 June 1997. The off-site, product-use test plan was updated in June of 1997. During this quarter, Acurex Environmental Corporation and Air Products screened proposals for this task by the likelihood of the projects to proceed and the timing for the initial methanol requirement. Eight sites from the list have met these criteria. The formal submission of the eight projects for review and concurrence by the DOE will be made during the next reporting period. The site paving and final painting were completed in May of 1997. Start-up activities were completed during the reporting period, and the initial methanol production from the demonstration unit occurred on 02 April 1997. The first extended stable operation at the nameplate capacity of 80,000 gallons per day (260 tons per day) took place on 06 April 1997. Pressure drop and resistance coefficient across the gas sparger at the bottom of the reactor increased over this initial operating period. The demonstration unit was shut down from 08 May -17 June 1997 as part of a scheduled complex outage for the Kingsport site. During this outage, the gas sparger was removed, cleaned, and reinstalled. After completion of other maintenance activities, the demonstration unit was restarted, and maintained stable operation through the remainder of the reporting period. Again, the gas sparger showed an increase in pressure drop and resistance since the restart, although not as rapidly as during the April-May operation. Fresh oil was introduced online for the first time to a new flush connection on the gas inlet line to the reactov the flush lowered the pressure drop by 1 psi. However, the effects were temporary, and the sparger resistance coefficient continued to increase. Additional flushing with both fresh oil and entrained slurry recovered in the cyclone and secondary oil knock-out drum will be attempted in order to stabilize the sparger resistance coefficient.

  17. An investigation of current controlled liquid phase epitaxial growth of III-V compounds

    Microsoft Academic Search

    A. Abul-Fadl

    1976-01-01

    The Peltier cooling and Peltier coefficients of n-type GaAs and n-type InP were measured by passing an electrical current through the GaAs-Ga and InP-In solid-melt interface, respectively, in a vertical liquid phase epitaxy system. Application of a steady-state heat transfer analysis yielded the following values for the Peltier coefficients of GaAs and InP: the coefficient for (II)GaAs is between 0.141

  18. Causes for deactivation in the liquid phase methanol synthesis catalyst

    SciTech Connect

    Lee, S. [Univ. of Akron, OH (United States); Kulik, C.J. [Electric Power Research Inst., Palo Alto, CA (United States)

    1994-12-31

    The commercial methanol synthesis catalyst in its unreduced form of CuO/ZnO/Al{sub 2}O{sub 3} must be reduced for the synthesis reaction to take place. Once the catalyst is fully activated via insitu reduction process, the catalyst is susceptible to various sources of deactivation. For the successful development of the liquid phase methanol synthesis process, the following problems with the catalyst deactivation, both internal and external, had to be solved: (a) poisoning by sulfur and carbonyls, (b) local spots and exothermic heat of reaction, (c) carbon fouling, (d) attrition, (e) leaching of catalyst ingredients, (f) thermal aging, and (g) crystallite size growth via hydrothermal synthesis. Both the symptoms and remedies of the above issues are discussed with experimental data and verification. This paper not only provides valuable information regarding the catalytic chemistry of methanol synthesis, but also elucidates the importance of catalytic process engineering in the development of a commercial catalytic reaction process.

  19. Aqueous Solubilities, Infinite Dilution Activity Coefficients and Octanol–Water Partition Coefficients of Tricyclic Analogs of Acyclovir

    Microsoft Academic Search

    W. Zielenkiewicz; B. Golankiewicz; G. L. Perlovich; M. Ko?bia?

    1999-01-01

    Solubilities of tricyclic analogs of acyclovir have been determined in water at 25, 35, and 45°C and in octanol, water-saturated octanol, and octanol-saturated water at 25°C. Octanol-water partition coefficients were determined at 25°C. Melting temperatures and molar enthalpies of fusion were measured. Activity coefficients in water, octanol, and in aqueous octanol solutions were determined and are discussed. The effect of

  20. Liquid phase methanol LaPorte process development unit: Modification, operation, and support studies

    SciTech Connect

    Not Available

    1991-02-02

    This report consists of Detailed Data Acquisition Sheets for Runs E-6 and E-7 for Task 2.2 of the Modification, Operation, and Support Studies of the Liquid Phase Methanol Laporte Process Development Unit. (Task 2.2: Alternate Catalyst Run E-6 and Catalyst Activity Maintenance Run E-7).

  1. Measurements of Peltier cooling at a Ga-GaAs interface using a liquid-phase epitaxy system

    Microsoft Academic Search

    E. K. Stefanakos; A. Abul-Fadl; M. D. Workman

    1975-01-01

    The Peltier coefficient of n-type GaAs was measured by passing an electrical current through the GaAs-Ga solid-liquid interface in a vertical liquid-phase epitaxy (LPE) system. Application of a steady-state heat-transfer analysis yielded values for the Peltier coefficient of 0.141 to 0.203 V in the 530–830 °C temperature range. From the study of measurements of Peltier cooling as a function of

  2. Measurements of Peltier cooling at a Ga-GaAs interface using a liquid-phase epitaxy system

    Microsoft Academic Search

    E. K. Stefanakos; A. Abul-Fadl; M. D. Workman

    1975-01-01

    The Peltier coefficient of n-type GaAs was measured by passing an electrical current through the GaAs-Ga solid-liquid interface in a vertical liquid-phase epitaxy (LPE) system. Application of a steady-state heat-transfer analysis yielded values for the Peltier coefficient of 0.141 to 0.203 V in the 530-830 °C temperature range. From the study of measurements of Peltier cooling as a function of

  3. Transfer having a coupling coefficient higher than its active material

    NASA Technical Reports Server (NTRS)

    Lesieutre, George A. (Inventor); Davis, Christopher L. (Inventor)

    2001-01-01

    A coupling coefficient is a measure of the effectiveness with which a shape-changing material (or a device employing such a material) converts the energy in an imposed signal to useful mechanical energy. Device coupling coefficients are properties of the device and, although related to the material coupling coefficients, are generally different from them. This invention describes a class of devices wherein the apparent coupling coefficient can, in principle, approach 1.0, corresponding to perfect electromechanical energy conversion. The key feature of this class of devices is the use of destabilizing mechanical pre-loads to counter inherent stiffness. The approach is illustrated for piezoelectric and thermoelectrically actuated devices. The invention provides a way to simultaneously increase both displacement and force, distinguishing it from alternatives such as motion amplification, and allows transducer designers to achieve substantial performance gains for actuator and sensor devices.

  4. 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)

  5. Transient liquid phase bonding of intermetallics

    NASA Astrophysics Data System (ADS)

    Guan, Yimin

    The present work was undertaken to examine the applicability of transient liquid phase bonding to structural intermetallics. This research was based on an investigation of the mechanisms governing microstructural development in the joint and adjacent substrates during the joining process. The bonding systems investigated included polycrystalline NiAl/Cu/Ni, polycrystalline NiAl/Cu/superalloys (Martin-Marietta (MM)-247, Inconel (IN) 718 and Nimonic 90), single-crystal NiAl (with 1.5 at % Hf) joined to MM-247 using different filler metals (Cu foil, powder filler metal and electro-plated thin Cu film), and martensitic NiAl joined with martensitic NiTi using Cu foil and specially designed powder filler metals. In polycrystalline NiAl/Cu/Ni bonds, the mechanism of isothermal solidification is considered. Changes in the microstructure of the bond centerline due to element redistribution are discussed. The precipitation of both L1sb2 type gammasp' and B2 type beta phase at the joint centerline is investigated. The formation of martensitic L1sb0 type NiAl is also examined. The mechanical properties of the joints are investigated using shear strength and microhardness tests. In TLP bonding of polycrystalline NiAl with MM-247, both the epitaxial growth of the beta phase NiAl into the joint and the formation of non-epitaxial beta-phase layers are considered. The formation of second-phases, including the gammasp' phase, carbides, and sigma-phase intermetallics is also examined. Bond-line and adjacent substrate microstructures for the NiAl/Cu/MM-247 bonds are correlated with joint mechanical properties determined by room temperature shear testing. Single-crystal NiAl (1.5 at % Hf)/Cu/MM-247 joints are examined and compared with polycrystalline NiAl/Cu/MM247 joints. The effect of Hf on the microstructure of joints is investigated. The influence of different filler metals (i.e., wide-gap powder filler metal and electro-plated thin film filler metal) on the joining process is also considered. In TLP bonding of martensitic NiAl with martensitic NiTi, the formation Ti depletion region was observed while using Cu foil as the filler metal. Alternative filler metals were successfully used to solve this problem. According to the experimental results, standard TLP bonding models cannot be applied to the bonding systems in this research. The influence of second phase formation on TLP models is discussed.

  6. Graphene via sonication assisted liquid-phase exfoliation.

    PubMed

    Ciesielski, Artur; Samorì, Paolo

    2014-01-01

    Graphene, the 2D form of carbon based material existing as a single layer of atoms arranged in a honeycomb lattice, has set the science and technology sectors alight with interest in the last decade in view of its astounding electrical and thermal properties, combined with its mechanical stiffness, strength and elasticity. Two distinct strategies have been undertaken for graphene production, i.e. the bottom-up and the top-down. The former relies on the generation of graphene from suitably designed molecular building blocks undergoing chemical reaction to form covalently linked 2D networks. The latter occurs via exfoliation of graphite into graphene. Bottom-up techniques, based on the organic syntheses starting from small molecular modules, when performed in liquid media, are both size limited, because macromolecules become more and more insoluble with increasing size, and suffer from the occurrence of side reactions with increasing molecular weight. Because of these reasons such a synthesis has been performed more and more on a solid (ideally catalytically active) surface. Substrate-based growth of single layers can be done also by chemical vapor deposition (CVD) or via reduction of silicon carbide, which unfortunately relies on the ability to follow a narrow thermodynamic path. Top-down approaches can be accomplished under different environmental conditions. Alongside the mechanical cleavage based on the scotch tape approach, liquid-phase exfoliation (LPE) methods are becoming more and more interesting because they are extremely versatile, potentially up-scalable, and can be used to deposit graphene in a variety of environments and on different substrates not available using mechanical cleavage or growth methods. Interestingly, LPE can be applied to produce different layered systems exhibiting different compositions such as BN, MoS2, WS2, NbSe2, and TaS2, thereby enabling the tuning of numerous physico-chemical properties of the material. Furthermore, LPE can be employed to produce graphene-based composites or films, which are key components for many applications, such as thin-film transistors, conductive transparent electrodes for indium tin oxide replacement, e.g. in light-emitting diodes, or photovoltaics. In this review, we highlight the recent progress that has led to successful production of high quality graphene by means of LPE of graphite. In particular, we discuss the mechanisms of exfoliation and methods that are employed for graphene characterization. We then describe a variety of successful liquid-phase exfoliation methods by categorizing them into two major classes, i.e. surfactant-free and surfactant-assisted LPE. Furthermore, exfoliation in aqueous and organic solutions is presented and discussed separately. PMID:24002478

  7. Measurement of gas/water uptake coefficients for trace gases active in the marine environment

    SciTech Connect

    Davidovits, P. (Boston Coll., Chestnut Hill, MA (United States). Dept. of Chemistry); Worsnop, D.W.; Zahniser, M.S.; Kolb, C.E. (Aerodyne Research, Inc., Billerica, MA (United States). Center for Chemical and Environmental Physics)

    1992-02-01

    Ocean produced reduced sulfur compounds including dimethylsulfide (DMS), hydrogen sulfide (H{sub 2}S), carbon disulfide (CS{sub 2}), methyl mercaptan (CH{sub 3}CH) and carbonyl sulfide (OCS) deliver a sulfur burden to the atmosphere which is roughly equal to sulfur oxides produced by fossil fuel combustion. These species and their oxidation products dimethyl sulfoxide (DMSO), dimethyl sulfone (DMSO{sub 2}) and methane sulfonic acid (MSA) dominate aerosol and CCN production in clean marine air. Furthermore, oxidation of reduced sulfur species will be strongly influenced by NO{sub x}/O{sub 3} chemistry in marine atmospheres. The multiphase chemical processes for these species must be understood in order to study the evolving role of combustion produced sulfur oxides over the oceans. We have measured the chemical and physical parameters affecting the uptake of reduced sulfur compounds, their oxidation products, ozone, and nitrogen oxides by the ocean's surface, and marine clouds, fogs, and aerosols. These parameters include: gas/surface mass accommodation coefficients; physical and chemically modified (effective) Henry's law constants; and surface and liquid phase reaction constants. These parameters are critical to understanding both the interaction of gaseous trace species with cloud and fog droplets and the deposition of trace gaseous species to dew covered, fresh water and marine surfaces.

  8. Feature and Mechanisms of Layer Growth in Liquid Phase Epitaxy of Semiconductor Materials

    Microsoft Academic Search

    M. Konuma

    \\u000a Liquid phase epitaxy (LPE) has been applied for growing mainly semiconductor materials [1, 2]. It may be required, when electrical and crystallographic quality of wafers which are cut from bulk crystals is not good\\u000a enough for making active devices directly on wafers, to grow same materials as substrates but better quality on wafers (homoepitaxy). Epitaxial growth can be also applied

  9. Limiting activity coefficients and gas-liquid partition coefficients of various solutes in piperidinium ionic liquids: measurements and LSER calculations.

    PubMed

    Paduszy?ski, Kamil; Doma?ska, Urszula

    2011-06-30

    This paper is a continuation of our systematic investigations on piperidinium ionic liquids and presents new data on activity coefficients at infinite dilution for 43 solutes: linear and branched alkanes, cycloalkanes, alkenes, alkynes, benzene, alkylbenzenes, alcohols, water, thiophene, tetrahyrdofuran (THF), methyl tert-butyl ether (MTBE), linear ethers, acetone, and linear ketones in the ionic liquid 1-butyl-1-methyl-piperidinium bis(trifluoromethylsulfonyl)imide, [BMPIP][NTf2]. The data were determined by gas-liquid chromatography (GLC) at temperatures from 308.15 to 358.15 K. These values were compared to those previously published for the bis-(trifluoromethylsulfonyl)imide-based ionic liquids. The partial molar excess enthalpies ?H1(E,?) and entropies ?S1(E,?) at infinite dilution were calculated from the experimental ?13(?) values obtained over the temperature range. The values of the selectivities for different separation problems were calculated from ?13(?) and compared to literature values for N-methyl-2-pyrrolidinone (NMP), sulfolane, and additional ionic liquids. Experimental limiting activity coefficients were used to calculate gas-IL partition coefficients of solutes, K(L). The modeling with specific linear solvation energy relationship (LSER) equations was performed for data obtained in this work and those reported earlier for 1-butyl-1-methylpiperidinium thiocyanate, [BMPIP][SCN]. PMID:21634373

  10. Liquid-Phase Processing of Barium Titanate Thin Films

    NASA Astrophysics Data System (ADS)

    Harris, David Thomas

    Processing of thin films introduces strict limits on the thermal budget due to substrate stability and thermal expansion mismatch stresses. Barium titanate serves as a model system for the difficulty in producing high quality thin films because of sensitivity to stress, scale, and crystal quality. Thermal budget restriction leads to reduced crystal quality, density, and grain growth, depressing ferroelectric and nonlinear dielectric properties. Processing of barium titanate is typically performed at temperatures hundreds of degrees above compatibility with metalized substrates. In particular integration with silicon and other low thermal expansion substrates is desirable for reductions in costs and wider availability of technologies. In bulk metal and ceramic systems, sintering behavior has been encouraged by the addition of a liquid forming second phase, improving kinetics and promoting densification and grain growth at lower temperatures. This approach is also widespread in the multilayer ceramic capacitor industry. However only limited exploration of flux processing with refractory thin films has been performed despite offering improved dielectric properties for barium titanate films at lower temperatures. This dissertation explores physical vapor deposition of barium titanate thin films with addition of liquid forming fluxes. Flux systems studied include BaO-B2O3, Bi2O3-BaB2O 4, BaO-V2O5, CuO-BaO-B2O3, and BaO-B2O3 modified by Al, Si, V, and Li. Additions of BaO-B2O3 leads to densification and an increase in average grain size from 50 nm to over 300 nm after annealing at 900 °C. The ability to tune permittivity of the material improved from 20% to 70%. Development of high quality films enables engineering of ferroelectric phase stability using residual thermal expansion mismatch in polycrystalline films. The observed shifts to TC match thermodynamic calculations, expected strain from the thermal expansion coefficients, as well as x-ray diffract measurements . Our system exhibits flux-film-substrate interactions that can lead to dramatic changes to the microstructure. This effect is especially pronounced onc -sapphire, with Al diffusion from the substrate leading to formation of an epitaxial BaAl2O4 second phase at the substrate-film interface. The formation of this second phase in the presence of a liquid phase seeds {111} twins that drive abnormal grain growth. The orientation of the sapphire substrate determines the BaAl2O 4 morphology, enabling control the abnormal grain growth behavior. CuO additions leads to significant grain growth at 900 °C, with average grain size approaching 500 nm. The orthorhombic-tetragonal phase transition is clearly observable in temperature dependent measurements and both linear and nonlinear dielectric properties are improved. All films containing CuO are susceptible to aging. A number of other systems were investigated for efficacy at temperatures below 900 °C. Pulsed laser deposition was used to study flux + BaTiO 3 targets, layered flux films, and in situ liquids. RF-magnetron sputtering using a dual-gun approach was used to explore integration on flexible foils with Ba1-xSrxTiO3. Many of these systems were based on the BaO-B2O3 system, which has proven effective in thin films, multilayer ceramic capacitors, and bulk ceramics. Modifiers allow tailoring of the microstructure at 900 °C, however no compositions were found, and no reports exist in the open literature, that provide significant grain growth or densification below 900 °C. Liquid phase fluxes offer a promising path forward for low temperature processing of barium titanate, with the ultimate goal of integration with metalized silicon substrates. This work demonstrates significant improvements to dielectric properties and the necessity of understanding interactions in the film-flux-substrate system.

  11. Radial and axial dispersion of the liquid phase within a KATAPAK-S ® structure: experiments vs. CFD simulations

    Microsoft Academic Search

    J. M van Baten; J. Ellenberger; R. Krishna

    2001-01-01

    The radial, and axial, liquid-phase dispersion within the catalytically packed criss-crossing sandwich structures of KATAPAK-S has been studied experimentally with the use of computational fluid dynamics (CFD). The KATAPAK-S structure has excellent radial dispersion characteristics. The radial dispersion coefficient in such structures is about one order of magnitude higher than that for conventional packed (trickle) beds. The CFD simulations of

  12. Commercial-Scale Demonstration of the Liquid Phase Methanol (LPMEOH(TM)) Process

    SciTech Connect

    None

    1996-12-31

    The Liquid Phase Methanol (LPMEOH(TM)) Demonstration Project at Kingsport, Tennessee, is a $213.7 million cooperative agreement between the U.S. Department of Energy (DOE) and Air Products Liquid Phase Conversion Company, L.P. (the Partnership). The LPMEOIWM Process Demonstration Unit is being built at a site located at the Eastman Chemical Company (Eastman) complex in Kingsport. During this quarter, the Cooperative Agreement was modified (Mod AO11) on 8 October 1996, authorizing the transition born Budget Period No. 2 (Design and Construction) to the . final Budget Period (Commissioning, Start-up, and Operation), A draft Topical Report on Process Economics Studies concludes that methanol coproduction with integrated gasification combined cycle (IGCC) electric power utilizing the LPMEOW process technology, will be competitive in serving local market needs. Planning for a proof-of- concept test run of the liquid phase dimethyl ether (DME) process at the LaPorte Alternative Fuels Development Unit (AFDU) was recommended; and a deeision to proceed is pending. Construction (Task 2.2) is 97'Mo complete, asof31 December 1996. Completion of pipe pressure testing has taken longer than expected. This will delay completion of construction by about three weeks. Commissioning activities (Task 2.3) commenced in mid-October of 1996, and the demonstration unit is scheduled to be mechanically complete on 24 January 1997.

  13. Commercial-Scale Demonstration of the Liquid Phase Methanol (LPMEOH(TM)) Process

    SciTech Connect

    None

    1997-09-30

    The Liquid Phase Methanol (LPMEOH) Demonstration Project at Kingsport, Tennessee, is a $213.7 million cooperative agreement between the U.S. Department of Energy (DOE) and Air Products Liquid Phase Conversion Company, L.P. (the Partnership). Ak Products and Chemicals, Inc. (Air Products) and Eastman Chemical Company (Eastman) formed the Partnership to execute the Demonstration Project. The LPMEOITM Process Demonstration Unit was built at a site located at the Eastman complex in Kingsport. During this reporting period, DOE accepted the recommendation to continue with dimethyl ether (DME) design verification testing (DVT). DME design verification testing studies show the liquid phase DME (LPDME) process will have a significant economic advantage for the coproduction of DME for local markets. An LPDME catalyst system with reasonable long-term activity and stzibility is being developed. Planning for a proof-of-concept test run at the LaPorte Alternative Fuels Development Unit (AFDU) was recommended. DOE issued a letter dated 31 July 1997 accepting the recommendation to continue design verification testing. In order to allow for scale-up of the manufacturing technique for the dehydration catalyst from the pilot plant to the commercial scale, the time required to produce the catalyst to the AFDU has slipped. The new estimated delivery date is 01 June 1998.

  14. High purity liquid phase epitaxial gallium arsenide nuclear radiation detector

    Microsoft Academic Search

    Dimitri Alexiev; K. S. A. Butcher

    1992-01-01

    Surface barrier radiation detector made from high purity liquid phase epitaxial gallium arsenide wafers have been operated as X- and gamma-ray detectors at various operating temperatures. Low energy isotopes are resolved including 241Am at 40°C and the higher gamma energies of 235U at -80°C.

  15. Chemical Liquid Phase Deposition of Thin Aluminum Oxide Films

    Microsoft Academic Search

    Jie Sun; Yingchun Sun

    2007-01-01

    Thin aluminum oxide films were deposited by a new and simple physicochemical method called chemical liquid phase deposition (CLD) on semiconductor materials. Aluminum sulfate with crystallized water and sodium bicarbonate were used as precursors for film growth, and the control of the system pH value played an important role in this experiment. The growth rate is 12 nm\\/h at room

  16. Recent Advances in the Liquid?Phase Synthesis of Metal Nanostructures with Controlled Shape and Size for Catalysis

    Microsoft Academic Search

    Natalia Semagina

    2009-01-01

    Recent advances in the liquid?phase synthesis of metal nanostructures of different sizes and shapes are reviewed regarding their catalytic properties. The controlled synthesis of nanostructures is based on the colloid chemistry techniques in the solution, which use organic nanoreactors and a variety of stabilizers. Their catalytic activity and selectivity depend on the particle's shape and size, as shown for Suzuki

  17. Activity coefficients at infinite dilution of alkanes and alkenes in 1-alkyl-3-methylimidazolium tetrafluoroborate

    Microsoft Academic Search

    Matthias Bahlmann; Silke Nebig; Jürgen Gmehling

    2009-01-01

    For the measurement of limiting activity coefficients different techniques are available. In this work the activity coefficients at infinite dilution ?i? of alkanes and alkenes in the ionic liquids 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM]+[BF4]? and 1-hexyl-3-methylimidazolium tetrafluoroborate [HMIM]+[BF4]? from 303.15K to 353.15K were measured with the help of the dilutor technique. The new data were compared with already published experimental data measured

  18. Microstructure evolution and densification of alumina in liquid phase sintering

    NASA Astrophysics Data System (ADS)

    Dong, Weimin

    The microstructure evolution and densification of alumina during liquid phase sintering were quantified. Quantification included the evolution of pore-size distribution, the redistribution of liquid phase, the densification kinetics, and the fraction of closed and open pores. The results revealed that the small and large pores were filled simultaneously. This is inconsistent with Shaw's model in which liquid fills preferentially the smaller low-coordination-number pores in order to reach a low-energy configuration. The results also recommended that the pressure build-up of the trapped gases in pores due to the closure of open pores might have a significantly negative contribution to the driving force, and consequently cause the termination of the densification of alumina. To demonstrate whether the trapped gases played an important role in the microstructure evolution and the densification of alumina during liquid phase sintering, the following two experiments have been conducted. First, alumina preforms containing artificial pores were penetrated by glass. The results indicated that the trapped gases in pores had a considerable influence on the pore filling process, and ultimately caused the termination of the densification of the alumina preforms. Second, alumina compacts containing different amount of glass were sintered in vacuum. The alumina compact containing 20 vol. % reached full density during vacuum sintering, indicating that the pressure build-up of the trapped gases in pores was the main factor causing the termination of the densification of alumina in the final stage of liquid phase sintering. The limiting relative densities of compacts were calculated theoretically on the basis of a comprehensive analysis of the variation of the capillary pressure and gas pressure in pores with pore size and pore number. The capillary pressure and gas pressure in alumina compact during liquid phase sintering were analyzed on the basis of the above theoretical models and the obtained quantitative experiment data. The calculated compressive pressure at particle contacts decreased significantly during the final stage of sintering due to the large increase of the gas pressure in the closed pores as the number of the closed pores and their size decreased. The derived time exponent of linear shrinkage from the decreasing compressive pressure at particle contacts and a modified Kingery's contact flattening model was consistent with the value obtained from the experimentally measured relative densities. These results indicated that the pressure build-up of the trapped gases in the compact was primarily responsible for the inhibited densification of the alumina compact in the final stage of liquid phase sintering.

  19. A single-component liquid-phase hydrogen storage material.

    PubMed

    Luo, Wei; Campbell, Patrick G; Zakharov, Lev N; Liu, Shih-Yuan

    2011-12-01

    The current state-of-the-art for hydrogen storage is compressed H(2) at 700 bar. The development of a liquid-phase hydrogen storage material has the potential to take advantage of the existing liquid-based distribution infrastructure. We describe a liquid-phase hydrogen storage material that is a liquid under ambient conditions (i.e., at 20 °C and 1 atm pressure), air- and moisture-stable, and recyclable; releases H(2) controllably and cleanly at temperatures below or at the proton exchange membrane fuel cell waste-heat temperature of 80 °C; utilizes catalysts that are cheap and abundant for H(2) desorption; features reasonable gravimetric and volumetric storage capacity; and does not undergo a phase change upon H(2) desorption. PMID:22070729

  20. Quantitative Evaluation of Colloidal Stability of Antibody Solutions using PEG-Induced Liquid-Liquid Phase Separation

    E-print Network

    Benedek, George B.

    pathways including crystallization, colloidal aggregation, and liquid-liquid phase separation (LLPS) can. KEYWORDS: antibody, PEG, liquid-liquid phase separation, colloidal stability, binding energy 1 of protein condensation such as crystallization, aggregation, gelation, and liquid-liquid phase separation

  1. Activity Coefficient Derivatives of Ternary Systems Based on Scatchard's Neutral Electrolyte description

    SciTech Connect

    Miller, D G

    2007-05-16

    Activity coefficient derivatives with respect to molality are presented for the Scatchard Neutral Electrolyte description of a ternary common-ion electrolyte system. These quantities are needed for the calculation of 'diffusion Onsager coefficients' and in turn for tests of the Onsager Reciprocal Relations in diffusion. The usually-omitted b{sub 23} term is included. The direct SNE binary approximations and a further approximation are discussed. Binary evaluation strategies other than constant ionic strength are considered.

  2. 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.

  3. Liquid-phase separation in glass-forming systems

    Microsoft Academic Search

    P. F. James

    1975-01-01

    This review is concerned with the process of liquid-phase separation in glass-forming systems. In the first part a general account of phase equilibria is presented together with a discussion of the thermodynamic behaviour of systems exhibiting liquid-liquid immiscibility. The estimation of free energies from phase-boundary data and the location of the spinodal boundary are briefly considered. The origin of immiscibility

  4. Solid + liquid phase equilibria in the hydroxylammonium nitrate + water system

    Microsoft Academic Search

    Johanne I. Artman; J. Bevan Ott

    1989-01-01

    The binary solid + liquid phase diagram has been measured for the water + hydroxylammonium nitrate (HAN) system. The phase diagram is a simple eutectic type with the eutectic at 231.5 K (41.7°C) and a mole fraction HAN of 0.281 (wt fraction HAN - 0.676).The enthalpy of fusion of the HAN was determined from the solid + liquid results to

  5. Oxidation Protection of Uranium Nitride Fuel using Liquid Phase Sintering

    SciTech Connect

    Dr. Paul A. Lessing

    2012-03-01

    Two methods are proposed to increase the oxidation resistance of uranium nitride (UN) nuclear fuel. These paths are: (1) Addition of USi{sub x} (e.g. U3Si2) to UN nitride powder, followed by liquid phase sintering, and (2) 'alloying' UN nitride with various compounds (followed by densification via Spark Plasma Sintering or Liquid Phase Sintering) that will greatly increase oxidation resistance. The advantages (high thermal conductivity, very high melting point, and high density) of nitride fuel have long been recognized. The sodium cooled BR-10 reactor in Russia operated for 18 years on uranium nitride fuel (UN was used as the driver fuel for two core loads). However, the potential advantages (large power up-grade, increased cycle lengths, possible high burn-ups) as a Light Water Reactor (LWR) fuel are offset by uranium nitride's extremely low oxidation resistance (UN powders oxidize in air and UN pellets decompose in hot water). Innovative research is proposed to solve this problem and thereby provide an accident tolerant LWR fuel that would resist water leaks and high temperature steam oxidation/spalling during an accident. It is proposed that we investigate two methods to increase the oxidation resistance of UN: (1) Addition of USi{sub x} (e.g. U{sub 3}Si{sub 2}) to UN nitride powder, followed by liquid phase sintering, and (2) 'alloying' UN nitride with compounds (followed by densification via Spark Plasma Sintering) that will greatly increase oxidation resistance.

  6. Accelerometer signal-based human activity recognition using augmented autoregressive model coefficients and artificial neural nets.

    PubMed

    Khan, A M; Lee, Y K; Kim, T S

    2008-01-01

    Automatic recognition of human activities is one of the important and challenging research areas in proactive and ubiquitous computing. In this work, we present some preliminary results of recognizing human activities using augmented features extracted from the activity signals measured using a single triaxial accelerometer sensor and artificial neural nets. The features include autoregressive (AR) modeling coefficients of activity signals, signal magnitude areas (SMA), and title angles (TA). We have recognized four human activities using AR coefficients (ARC) only, ARC with SMA, and ARC with SMA and TA. With the last augmented features, we have achieved the recognition rate above 99% for all four activities including lying, standing, walking, and running. With our proposed technique, real time recognition of some human activities is possible. PMID:19163882

  7. Synthesis of dimethyl ether and alternative fuels in the liquid phase from coal-derived synthesis gas. Final technical report

    SciTech Connect

    Not Available

    1993-02-01

    Through the mid-1980s, Air Products has brought the liquid phase approach to a number of other synthesis gas reactions where effective heat management is a key issue. In 1989, in response to DOE`s PRDA No. DE-RA22-88PC88805, Air Products proposed a research and development program entitled ``Synthesis of Dimethyl Ether and Alternative Fuels in the Liquid Phase from Coal Derived Syngas.`` The proposal aimed at extending the LPMEOH experience to convert coal-derived synthesis gas to other useful fuels and chemicals. The work proposed included development of a novel one-step synthesis of dimethyl ether (DME) from syngas, and exploration of other liquid phase synthesis of alternative fuel directly from syngas. The one-step DME process, conceived in 1986 at Air Products as a means of increasing syngas conversion to liquid products, envisioned the concept of converting product methanol in situ to DME in a single reactor. The slurry reactor based liquid phase technology is ideally suited for such an application, since the second reaction (methanol to DME) can be accomplished by adding a second catalyst with dehydration activity to the methanol producing reactor. An area of exploration for other alternative fuels directly from syngas was single-step slurry phase synthesis of hydrocarbons via methanol and DME as intermediates. Other possibilities included the direct synthesis of mixed alcohols and mixed ethers in a slurry reactor.

  8. Methodology for using prompt gamma activation analysis to measure the binary diffusion coefficient of a gas in a porous medium

    E-print Network

    Deinert, Mark

    Methodology for using prompt gamma activation analysis to measure the binary diffusion coefficient to determine the binary diffusion coefficients of a gas in a porous system. Argon diffusion experiments were- suring the binary diffusion coefficient of a gas in a geological med- ium using prompt gamma activation

  9. A Robust Computational Method for Coupled Liquid-liquid Phase Separation and Gas-particle Partitioning Predictions of Multicomponent Aerosols

    NASA Astrophysics Data System (ADS)

    Zuend, A.; Di Stefano, A.

    2014-12-01

    Providing efficient and reliable model predictions for the partitioning of atmospheric aerosol components between different phases (gas, liquids, solids) is a challenging problem. The partitioning of water, various semivolatile organic components, inorganic acids, bases, and salts, depends simultaneously on the chemical properties and interaction effects among all constituents of a gas + aerosol system. The effects of hygroscopic particle growth on the water contents and physical states of potentially two or more liquid and/or solid aerosol phases in turn may significantly affect multiphase chemistry, the direct effect of aerosols on climate, and the ability of specific particles to act as cloud condensation or ice nuclei. Considering the presence of a liquid-liquid phase separation in aerosol particles, which typically leads to one phase being enriched in rather hydrophobic compounds and the other phase enriched in water and dissolved electrolytes, adds a high degree of complexity to the goal of predicting the gas-particle partitioning of all components. Coupled gas-particle partitioning and phase separation methods are required to correctly account for the phase behaviour of aerosols exposed to varying environmental conditions, such as changes to relative humidity. We present new theoretical insights and a substantially improved algorithm for the reliable prediction of gas-particle partitioning at thermodynamic equilibrium based on the Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) model. We introduce a new approach for the accurate prediction of the phase distribution of multiple inorganic ions between two liquid phases, constrained by charge balance, and the coupling of the liquid-liquid equilibrium model to a robust gas-particle partitioning algorithm. Such coupled models are useful for exploring the range of environmental conditions leading to complete or incomplete miscibility of aerosol constituents which will affect other particle properties, such as the viscosity of aerosol phases. The method has been applied successfully to the calculation of gas-liquid-liquid-solid equilibria used for the prediction of aerosol hygroscopicity (humidity cycles) in comparison to laboratory experiments on aerosol water uptake and phase behaviour.

  10. Activity coefficients of microquantities of lanthanides and actinides in nitric acid solutions

    SciTech Connect

    Vlasov, V.S.; Rozen, A.M.

    1988-09-01

    We carried out calculations on the basis of the Zdanovskii-Mikulin rule. The radii of the ions of the actinides americium and curium(III) (0.099 nm) are closest to the radius of the neodymium ion (0.0995 nm), and the radius of the californium ion (0.0976 nm) is closest to the radius of the promethium ion (0.0979 nm). It may accordingly be assumed that the activity coefficients of americium and curium are approximately equal to the activity coefficients of neodymium and that the values for californium are approximately equal to the values for promethium.

  11. Liquid phase hydrogenation of furfural to furfuryl alcohol over the Fe-promoted NiB amorphous alloy catalysts

    Microsoft Academic Search

    Hexing Li; Hongshan Luo; Li Zhuang; Weilin Dai; Minghua Qiao

    2003-01-01

    The ultrafine Fe-doped Ni-B amorphous catalyst (Ni-Fe-B) was prepared by reducing mixed FeCl3 and NiCl2 with KBH4 in aqueous solution. At suitable Fe-content (?Fe), the Ni-Fe-B amorphous catalyst exhibited much higher activity than the corresponding undoped Ni-B in the liquid phase hydrogenation of furfural (FFR) to furfuryl alcohol (FFA). With the increase of ?Fe, the activity first increased and then

  12. Predicting chromium (VI) adsorption rate in the treatment of liquid-phase oil-based drill cuttings

    Microsoft Academic Search

    Reuben N. Okparanma; Miebaka J. Ayotamuno

    2008-01-01

    The adsorption rate of chromium (VI) on commercial activated carbon during the treatment of the flocculation effluent of liquid-phase oil-based drill-cuttings has been investigated in terms of contact time and initial chromium (VI) ion concentration. Homogenizing 1 g of the activated carbon with 100 ml of the flocculation effluent of known initial concentrations (1.25 ? 6.25 mg\\/l, in turn) in

  13. Finite Temperature Transport in a Non-Fermi Liquid Phase of a Quadratic Semimetal

    NASA Astrophysics Data System (ADS)

    Dumitrescu, Philipp

    2015-03-01

    We study finite temperature transport in the Luttinger-Abrikosov-Beneslavskii phase - an interacting, scale invariant, non-Fermi liquid phase found in quadratic semimetals which has been recently suggested to be realized in strongly correlated pyrochlore iridate systems. We develop a kinetic equation formalism to describe the d.c. transport properties, which are dominated by collisions, and consider the shear viscosity ? as a model transport coefficient. The ratio of shear viscosity to entropy density ? / s is a measure of the strength of interaction between the excitations of a quantum fluid. As a consequence of the quantum critical nature of the system, ? / s is a universal number and we find it to be consistent with a bound proposed from gauge-gravity duality.

  14. Temperature Dependent Raman Studies on Liquid Phase Exfoliated MoS2

    NASA Astrophysics Data System (ADS)

    Connolly, Mitchell; Winchester, Andrew; Hale, Peter; Dani, Keshav M.; Talapatra, Saikat; Nanophysics Lab, Department of Physics, Southern Illinois University-Carbondale, USA Team; Femtosecond Spectroscopy Unit, Okinawa Institute of Science; Technology, Japan Team

    2014-03-01

    We investigate on the temperature dependence of in-plane E12g and out-of-plane A1g Raman modes of few-layer MoS2 prepared using the liquid-phase exfoliation method. Structural characterization performed after exfoliation using transmission electron microscopy (TEM) indicate the resultant material contains small, submicron size, few-layer flakes. Raman measurements indicating material thickness of 6 layers or fewer were observed at room temperature using a 532 nm laser line (E12g =381.4 cm-1 and A1g =405.8 cm-1). The Raman peak shifts indicate a linear dependence on temperature within the range 293 K to 77 K. The measured temperature coefficients of E12g and A1g modes will be presented and compared with other similar experimental/theoretical data available.

  15. Molecular interactions in 1-butanol + IL solutions by measuring and modeling activity coefficients.

    PubMed

    Nann, Alexander; Mündges, Jan; Held, Christoph; Verevkin, Sergey P; Sadowski, Gabriele

    2013-03-21

    Molecular interactions in 1-butanol + ionic liquid (IL) solutions have been investigated by measuring and modeling activity-coefficient data. The activity coefficients in binary solutions containing 1-butanol and an IL were determined experimentally: the ILs studied were 1-decyl-3-methyl-imidazolium tetracyanoborate ([Im10.1](+)[tcb](-)), 4-decyl-4-methyl-morpholinium tetracyanoborate ([Mo10.1](+)[tcb](-)), 1-decyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide ([Im10.1](+)[ntf2](-)), and 4-decyl-4-methyl-morpholinium bis(trifluoromethylsulfonyl)imide ([Mo10.1](+)[ntf2](-)). The methods used to determine the activity coefficients included vapor-pressure osmometry, headspace-gas chromatography, and gas-liquid chromatography. The results from all of these techniques were combined to obtain activity-coefficient data over the entire IL concentration range, and the ion-specific interactions of the ILs investigated were identified with 1-butanol. The highest (1-butanol)-IL interactions of the ILs considered in this work were found for [Im10.1](+)[tcb](-); thus, [Im10.1](+)[tcb](-) showed the highest affinity for 1-butanol in a binary mixture. The experimental data were modeled with the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT). PC-SAFT was able to accurately describe the pure IL and (1-butanol)-IL data. Moreover, the model was shown to be predictive and extrapolative with respect to concentration and temperature. PMID:23473581

  16. Extending the Diffuse Layer Model of Surface Acidity Behavior: III. Estimating Bound Site Activity Coefficients

    EPA Science Inventory

    Although detailed thermodynamic analyses of the 2-pK diffuse layer surface complexation model generally specify bound site activity coefficients for the purpose of accounting for those non-ideal excess free energies contributing to bound site electrochemical potentials, in applic...

  17. Environmental information volume: Liquid Phase Methanol (LPMEOH{trademark}) project

    SciTech Connect

    NONE

    1996-05-01

    The purpose of this project is to demonstrate the commercial viability of the Liquid Phase Methanol Process using coal-derived synthesis gas, a mixture of hydrogen and carbon monoxide. This report describes the proposed actions, alternative to the proposed action, the existing environment at the coal gasification plant at Kingsport, Tennessee, environmental impacts, regulatory requirements, offsite fuel testing, and DME addition to methanol production. Appendices include the air permit application, solid waste permits, water permit, existing air permits, agency correspondence, and Eastman and Air Products literature.

  18. Liquid phase synthesis of copper indium diselenide nanoparticles

    SciTech Connect

    Jakhmola, Priyanka; Agarwal, Garima; Jha, Prafulla K.; Bhatnagar, S. P. [Department of Physics, MaharajaKrishnakumar Sinhji, Bhavnagar University, Bhavnagar-364001 (India)

    2014-04-24

    Nanoparticles of Copper Indium diselenide (CuInSe{sub 2}), belongs to I-III-VI{sub 2} family has been synthesized via liquid phase route using ethylenediamine as a solvent. Characterization of as-grown particles is done by XRD, HRTEM, DLS, optical microscopy and UV-Vis spectroscopy. X-ray diffraction pattern confirmed that the CuInSe2 nanoparticles obtained reveals chalcopyrite structure. Particle size evaluated from dynamic light scattering of as grown particle possessing radius of 90 nm. The bandgap of 1.05eV is obtained from UV-Vis spectrum which will applicable to the solar cell devices.

  19. Vapors-liquid phase separator. [infrared telescope heat sink

    NASA Technical Reports Server (NTRS)

    Frederking, T. H. K.; Brown, G. S.; Chuang, C.; Kamioka, Y.; Kim, Y. I.; Lee, J. M.; Yuan, S. W. K.

    1980-01-01

    The use of porous plugs, mostly with in the form of passive devices with constant area were considered as vapor-liquid phase separators for helium 2 storage vessels under reduced gravity. The incorporation of components with variable cross sectional area as a method of flow rate modification was also investigated. A particular device which uses a shutter-type system for area variation was designed and constructed. This system successfully permitted flor rate changes of up to plus or minus 60% from its mean value.

  20. Porous Liquid Phases for Indented Colloids with Depletion Interactions

    NASA Astrophysics Data System (ADS)

    Ashton, Douglas J.; Jack, Robert L.; Wilding, Nigel B.

    2015-06-01

    We study indented spherical colloids, interacting via depletion forces. These systems exhibit liquid-vapor phase transitions whose properties are determined by a combination of strong "lock-and-key" bonds and weaker nonspecific interactions. As the propensity for lock-and-key binding increases, the critical point moves to significantly lower density, and the coexisting phases change their structure. In particular, the liquid phase is porous, exhibiting large percolating voids. The properties of this system depend strongly on the topological structure of an underlying bond network: we comment on the implications of this fact for the assembly of equilibrium states with controlled porous structures.

  1. Heterogeneous liquid phase synthesis of 3,4-dihydropyrimidine-2(1H)-ones using aluminated mesoporous silica

    Microsoft Academic Search

    Amit Dubey; Braja Gopal Mishra; Divya Sachdev; M. Sowmiya

    2008-01-01

    Aluminated mesoporous silica (Al-SBA-15) with different amounts of Al contents were synthesized and used for the synthesis\\u000a of 3,4-dihydropyrimidine-2(1H)-ones in the liquid phase, as well as under microwave conditions. The catalytic activity results\\u000a showed very high conversion and yields of the products over many substituted aromatic aldehydes.

  2. Infinite dilution activity coefficient and vapour liquid equilibrium measurements for dimethylsulphide and tetrahydrothiophene with hydrocarbons

    Microsoft Academic Search

    Piia Haimi; Petri Uusi-Kyyny; Juha-Pekka Pokki; Ville Alopaeus

    2010-01-01

    The activity coefficients at infinite dilution (??) of dimethylsulphide (DMS) in four hydrocarbon solvents were measured using the dilutor technique at temperatures between 288K and 303K. The four hydrocarbons were hexane, 1-hexene, 2,2,4-trimethylpentane and 2,4,4-trimethyl-1-pentene. The dilutor technique is based on the stripping of the highly diluted solute, i.e. DMS, by a constant flow of inert gas. The gas composition

  3. Flash flow pyrolysis: mimicking flash vacuum pyrolysis in a high-temperature/high-pressure liquid-phase microreactor environment.

    PubMed

    Cantillo, David; Sheibani, Hassan; Kappe, C Oliver

    2012-03-01

    Flash vacuum pyrolysis (FVP) is a gas-phase continuous-flow technique where a substrate is sublimed through a hot quartz tube under high vacuum at temperatures of 400-1100 °C. Thermal activation occurs mainly by molecule-wall collisions with contact times in the region of milliseconds. As a preparative method, FVP is used mainly to induce intramolecular high-temperature transformations leading to products that cannot easily be obtained by other methods. It is demonstrated herein that liquid-phase high-temperature/high-pressure (high-T/p) microreactor conditions (160-350 °C, 90-180 bar) employing near- or supercritical fluids as reaction media can mimic the results obtained using preparative gas-phase FVP protocols. The high-T/p liquid-phase "flash flow pyrolysis" (FFP) technique was applied to the thermolysis of Meldrum's acid derivatives, pyrrole-2,3-diones, and pyrrole-2-carboxylic esters, producing the expected target heterocycles in high yields with residence times between 10 s and 10 min. The exact control over flow rate (and thus residence time) using the liquid-phase FFP method allows a tuning of reaction selectivities not easily achievable using FVP. Since the solution-phase FFP method does not require the substrate to be volatile any more--a major limitation in classical FVP--the transformations become readily scalable, allowing higher productivities and space-time yields compared with gas-phase protocols. Differential scanning calorimetry measurements and extensive DFT calculations provided essential information on pyrolysis energy barriers and the involved reaction mechanisms. A correlation between computed activation energies and experimental gas-phase FVP (molecule-wall collisions) and liquid-phase FFP (molecule-molecule collisions) pyrolysis temperatures was derived. PMID:22321044

  4. Measurement of activity coefficients at infinite dilution for acetonitrile, water, limonene, limonene epoxide and their binary pairs

    Microsoft Academic Search

    Rolando Barrera Zapata; Aída Luz Villa; Consuelo Montes de Correa

    2009-01-01

    Activity coefficients at infinite dilution were determined for binary pairs of acetonitrile, water, limonene and limonene epoxide at room temperature using the dilutor technique (inert gas stripping) in a home-made dilutor apparatus. The activity coefficients were predicted with the Aspen Plus software using the Dortmund-modified UNIFAC contribution method. Values predicted by software simulations are in good agreement with experimental data.

  5. Predicting the activity coefficients of free-solvent for concentrated globular protein solutions using independently determined physical parameters.

    PubMed

    McBride, Devin W; Rodgers, Victor G J

    2013-01-01

    The activity coefficient is largely considered an empirical parameter that was traditionally introduced to correct the non-ideality observed in thermodynamic systems such as osmotic pressure. Here, the activity coefficient of free-solvent is related to physically realistic parameters and a mathematical expression is developed to directly predict the activity coefficients of free-solvent, for aqueous protein solutions up to near-saturation concentrations. The model is based on the free-solvent model, which has previously been shown to provide excellent prediction of the osmotic pressure of concentrated and crowded globular proteins in aqueous solutions up to near-saturation concentrations. Thus, this model uses only the independently determined, physically realizable quantities: mole fraction, solvent accessible surface area, and ion binding, in its prediction. Predictions are presented for the activity coefficients of free-solvent for near-saturated protein solutions containing either bovine serum albumin or hemoglobin. As a verification step, the predictability of the model for the activity coefficient of sucrose solutions was evaluated. The predicted activity coefficients of free-solvent are compared to the calculated activity coefficients of free-solvent based on osmotic pressure data. It is observed that the predicted activity coefficients are increasingly dependent on the solute-solvent parameters as the protein concentration increases to near-saturation concentrations. PMID:24324733

  6. Measurement of gas/water uptake coefficients for trace gases active in the marine environment. [Annual report

    SciTech Connect

    Davidovits, P. [Boston Coll., Chestnut Hill, MA (United States). Dept. of Chemistry; Worsnop, D.W.; Zahniser, M.S.; Kolb, C.E. [Aerodyne Research, Inc., Billerica, MA (United States). Center for Chemical and Environmental Physics

    1992-02-01

    Ocean produced reduced sulfur compounds including dimethylsulfide (DMS), hydrogen sulfide (H{sub 2}S), carbon disulfide (CS{sub 2}), methyl mercaptan (CH{sub 3}CH) and carbonyl sulfide (OCS) deliver a sulfur burden to the atmosphere which is roughly equal to sulfur oxides produced by fossil fuel combustion. These species and their oxidation products dimethyl sulfoxide (DMSO), dimethyl sulfone (DMSO{sub 2}) and methane sulfonic acid (MSA) dominate aerosol and CCN production in clean marine air. Furthermore, oxidation of reduced sulfur species will be strongly influenced by NO{sub x}/O{sub 3} chemistry in marine atmospheres. The multiphase chemical processes for these species must be understood in order to study the evolving role of combustion produced sulfur oxides over the oceans. We have measured the chemical and physical parameters affecting the uptake of reduced sulfur compounds, their oxidation products, ozone, and nitrogen oxides by the ocean`s surface, and marine clouds, fogs, and aerosols. These parameters include: gas/surface mass accommodation coefficients; physical and chemically modified (effective) Henry`s law constants; and surface and liquid phase reaction constants. These parameters are critical to understanding both the interaction of gaseous trace species with cloud and fog droplets and the deposition of trace gaseous species to dew covered, fresh water and marine surfaces.

  7. Spike detection in human muscle sympathetic nerve activity using the kurtosis of stationary wavelet transform coefficients

    PubMed Central

    Brychta, Robert J.; Shiavi, Richard; Robertson, David; Diedrich, André

    2007-01-01

    The accurate assessment of autonomic sympathetic function is important in the diagnosis and study of various autonomic and cardiovascular disorders. Sympathetic function in humans can be assessed by recording the muscle sympathetic nerve activity, which is characterized by synchronous neuronal discharges separated by periods of neural silence dominated by colored Gaussian noise. The raw nerve activity is generally rectified, integrated, and quantified using the integrated burst rate or area. We propose an alternative quantification involving spike detection using a two-stage stationary wavelet transform (SWT) de-noising method. The SWT coefficients are first separated into noise-related and burst-related coefficients on the basis of their local kurtosis. The noise-related coefficients are then used to establish a threshold to identify spikes within the bursts. This method demonstrated better detection performance than an unsupervised amplitude discriminator and similar wavelet-based methods when confronted with simulated data of varying burst rate and signal to noise ratio. Additional validation on data acquired during a graded head-up tilt protocol revealed a strong correlation between the mean spike rate and the mean integrate burst rate (r = 0.85) and burst area rate (r = 0.91). In conclusion, the kurtosis-based wavelet de-noising technique is a potentially useful method of studying sympathetic nerve activity in humans. PMID:17083982

  8. 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

  9. Fluoride waveguide lasers grown by liquid phase epitaxy

    NASA Astrophysics Data System (ADS)

    Starecki, Florent; Bolaños, Western; Brasse, Gurvan; Benayad, Abdelmjid; Doualan, Jean-Louis; Braud, Alain; Moncorgé, Richard; Camy, Patrice

    2013-03-01

    High optical quality rare-earth-doped LiYF4 (YLF) epitaxial layers were grown on pure YLF substrates by liquid phase epitaxy (LPE). Thulium, praseodymium and ytterbium YLF crystalline waveguides co-doped with gadolinium and/or lutetium were obtained. Spectroscopic and optical characterization of these rare-earth doped waveguides are reported. Internal propagation losses as low as 0.11 dB/cm were measured on the Tm:YLF waveguide and the overall spectroscopic characteristics of the epitaxial layers were found to be comparable to bulk crystals. Laser operation was achieved at 1.87 ?m in the Tm3+ doped YLF planar waveguide with a very good efficiency of 76% with respect to the pump power. Lasing was also demonstrated in a Pr3+ doped YLF waveguide in the red and orange regions and in a Yb3+:YLF planar waveguide at 1020 nm and 994 nm.

  10. Microstructure development and solid state reactions during liquid phase sintering

    SciTech Connect

    Yokoi, Hitoshi [NGK Spark Plug Co., Ltd., Aichi (Japan); Kingery, W.D. [Univ. of Arizona, Tucson, AZ (United States)

    1996-12-31

    Microstructure development during heating of alumina powders coated with precursors of various metal oxides has been examined. EM studies revealed that the alumina particle surfaces act as sites for heterogeneous nucleation. The solid solution between alumina and titania after the nucleation of rutile on the surface of alumina resulted in sintering rate enhancement, while the slow self-diffusion characteristics of zirconia resulted in {open_quotes}droplets{close_quotes} on the surface of alumina which impeded the grain boundary migration. The final structure of the alumina simultaneously doped with cupric oxide and titania or bismuth oxide and titania was reached in the presence of a liquid phase but large shrinkage occurred before the liquid formed. It was concluded that when a solid state reaction takes place between a matrix phase and a second phase or between second phases during heating, matter transfer is faster and thereby, the sintering is accelerated.

  11. Correlation and prediction of partition coefficient using nonrandom two-liquid segment activity coefficient model for solvent system selection in counter-current chromatography separation.

    PubMed

    Ren, Da-Bing; Yang, Zhao-Hui; Liang, Yi-Zeng; Ding, Qiong; Chen, Chen; Ouyang, Mei-Lan

    2013-08-01

    Selection of a suitable solvent system is the first and foremost step for a successful counter-current chromatography (CCC) separation. In this paper, a thermodynamic model, nonrandom two-liquid segment activity coefficient model (NRTL-SAC) which uses four types of conceptual segments to describe the effective surface interactions for each solvent and solute molecule, was employed to correlate and predict the partition coefficients (K) of a given compound in a specific solvent system. Then a suitable solvent system was selected according to the predicted partition coefficients. Three solvent system families, heptane/methanol/water, heptane/ethyl acetate/methanol/water (Arizona) and hexane/ethyl acetate/methanol/water, and several solutes were selected to investigate the effectiveness of the NRTL-SAC model for predicting the partition coefficients. Comparison between experimental results and predicted results showed that the NRTL-SAC model is of potential for estimating the K value of a given compound. Also a practical separation case on magnolol and honokiol suggests the NRTL-SAC model is effective, reliable and practical for the purpose of predicting partition coefficients and selecting a suitable solvent system for CCC separation. PMID:23806351

  12. Toward a complete description of nucleation and growth in liquid-liquid phase separation

    E-print Network

    Paris-Sud XI, Université de

    Toward a complete description of nucleation and growth in liquid-liquid phase separation Short separation mechanism of a binary liquid mixture off-critically quenched in its miscibility gap is nucleation separates in two phases. This liquid-liquid phase separation gives the opportunity to observe the pathway

  13. Ultrafast dynamics of the laser-induced solid-to-liquid phase transition in aluminum

    E-print Network

    Mazur, Eric

    for aluminum by optical exper- iments that demonstrated transition of the optical properties from solid properties during the solid-to-liquid phase transition in aluminum agree with the results obtained to the conclusion that the laser-induced, solid-to-liquid phase transition in aluminum is a thermal process. #12

  14. Bacterial 16S rRNA\\/rDNA Profiling in the Liquid Phase of Human Saliva

    Microsoft Academic Search

    F. Gu; Y. Li; C. Zhou; D. T. W. Wong; C. M. Ho; F. Qi; W. Shi

    2009-01-01

    Human saliva can be separated by centrifugation into cell pellet and cell-free supernatant, which are called cellu- lar phase and liquid phase in this study. While it is well documented that the cellular phase of saliva contains hundreds of oral bacteria species, little is known whether the liquid phase of saliva contains any information related to oral microbiota. In this

  15. Sulfonation of Methane Direct Liquid-Phase Sulfonation of Methane to

    E-print Network

    Bell, Alexis T.

    Sulfonation of Methane Direct Liquid-Phase Sulfonation of Methane to Methanesulfonic Acid by SO3- radical initiator to sulfonate methane with SO3 in fuming sulfuric acid.[6] However, even with a methane that methane will undergo liquid-phase sulfonation with 30 wt% SO3 in sulfuric acid to form MSA, using metal

  16. Mathematical Modeling and Experimental Investigations of Isothermal Solidification during Transient Liquid Phase Bonding of Nickel

    E-print Network

    Medraj, Mamoun

    Liquid Phase Bonding of Nickel Superalloys M. A. Arafin1, a , M. Medraj1, b , D. P. Turner2, c and P Liquid Phase Bonding, Nickel Superalloys. Abstract. Mathematical model, based on Fick's second law with nickel based brazing filler alloy BNi-2. Experimental investigations were carried out in the range

  17. Critical interlayer thickness for transient liquid phase bonding in the CuSn system

    E-print Network

    Zok, Frank

    Critical interlayer thickness for transient liquid phase bonding in the Cu­Sn system N.S. Bosco, F during transient liquid phase (TLP) bonding in the Cu­Sn system. Such pores are a consequence of the growth and subsequent contact of Cu6Sn5 intermetallic grains on the two surfaces to be bonded, prior

  18. Glass and liquid phase diagram of a polyamorphic monatomic system

    NASA Astrophysics Data System (ADS)

    Reisman, Shaina; Giovambattista, Nicolas

    2013-02-01

    We perform out-of-equilibrium molecular dynamics (MD) simulations of a monatomic system with Fermi-Jagla (FJ) pair potential interactions. This model system exhibits polyamorphism both in the liquid and glass state. The two liquids, low-density (LDL) and high-density liquid (HDL), are accessible in equilibrium MD simulations and can form two glasses, low-density (LDA) and high-density amorphous (HDA) solid, upon isobaric cooling. The FJ model exhibits many of the anomalous properties observed in water and other polyamorphic liquids and thus, it is an excellent model system to explore qualitatively the thermodynamic properties of such substances. The liquid phase behavior of the FJ model system has been previously characterized. In this work, we focus on the glass behavior of the FJ system. Specifically, we perform systematic isothermal compression and decompression simulations of LDA and HDA at different temperatures and determine "phase diagrams" for the glass state; these phase diagrams varying with the compression/decompression rate used. We obtain the LDA-to-HDA and HDA-to-LDA transition pressure loci, PLDA-HDA(T) and PHDA-LDA(T), respectively. In addition, the compression-induced amorphization line, at which the low-pressure crystal (LPC) transforms to HDA, PLPC-HDA(T), is determined. As originally proposed by Poole et al. [Phys. Rev. E 48, 4605 (1993)], 10.1103/PhysRevE.48.4605 simulations suggest that the PLDA-HDA(T) and PHDA-LDA(T) loci are extensions of the LDL-to-HDL and HDL-to-LDL spinodal lines into the glass domain. Interestingly, our simulations indicate that the PLPC-HDA(T) locus is an extension, into the glass domain, of the LPC metastability limit relative to the liquid. We discuss the effects of compression/decompression rates on the behavior of the PLDA-HDA(T), PHDA-LDA(T), PLPC-HDA(T) loci. The competition between glass polyamorphism and crystallization is also addressed. At our "fast rate," crystallization can be partially suppressed and the glass phase diagram can be related directly with the liquid phase diagram. However, at our "slow rate," crystallization cannot be prevented at intermediate temperatures, within the glass region. In these cases, multiple crystal-crystal transformations are found upon compression/decompression (polymorphism).

  19. Microstructural control of silicon carbide via liquid phase sintering

    NASA Astrophysics Data System (ADS)

    Mrotek, Sharon Robinson

    Silicon carbide ceramics with various microstructures were fabricated by controlling the amount and composition of a Y2O3-Al 2O3 liquid phase, crystallographic phase of the starting powders, trace impurities in those powders, and time and temperature of sintering and post- sintering heat-treatments. Alpha and beta SiC "seeds" were used to control grain growth during sintering. The grain size distribution and aspect ratio of the grains were determined through microstructural analysis of polished and etched samples. TEM was used in conjunction with EDS to determine the distribution of the sintering aids in the grains and the grain boundaries. Additionally, the final phase content of the samples was determined via x-ray diffraction. The fracture toughness and hardness were measured to evaluate the relative effects of the microstructural variations on the mechanical properties. Alpha silicon carbide samples exhibited a fine grained, equiaxed microstructure. Under appropriate conditions, samples prepared from beta-SiC powders underwent a phase transformation to alpha-SiC accompanied by the growth of elongated platelet grains. The addition of alpha seeds to the beta powder reduced the size of the platelets compared to unseeded samples of the same composition. If the beta to alpha phase transformation did not occur, the beta samples developed an equiaxed microstructure. The grain size of all samples decreased with increasing amounts of sintering additives. The beta to alpha phase transformation, required to obtain an elongated grain microstructure, was catalyzed by the presence of sufficient amounts of aluminum. If insufficient Al impurity was present in the powder, purposeful additions of Al metal could induce the phase transformation. Examination of the sintering progression over time indicated that the phase transformation occurred late in the sintering process and appeared to occur via a solution/reprecipitation mechanism. Post-sintering heat treatments were also used to encourage the beta to alpha phase transformation. However, the heat treatments were accompanied by high weight loss and volatilization of significant amounts of alumina from the liquid phase. Since fracture toughness was a function of the final grain morphology, the formation of large interlocking platelets was critical in obtaining the desired high toughness values.

  20. Hyperdoping silicon with selenium: solid vs. liquid phase epitaxy

    PubMed Central

    Zhou, Shengqiang; Liu, Fang; Prucnal, S.; Gao, Kun; Khalid, M.; Baehtz, C.; Posselt, M.; Skorupa, W.; Helm, M.

    2015-01-01

    Chalcogen-hyperdoped silicon shows potential applications in silicon-based infrared photodetectors and intermediate band solar cells. Due to the low solid solubility limits of chalcogen elements in silicon, these materials were previously realized by femtosecond or nanosecond laser annealing of implanted silicon or bare silicon in certain background gases. The high energy density deposited on the silicon surface leads to a liquid phase and the fast recrystallization velocity allows trapping of chalcogen into the silicon matrix. However, this method encounters the problem of surface segregation. In this paper, we propose a solid phase processing by flash-lamp annealing in the millisecond range, which is in between the conventional rapid thermal annealing and pulsed laser annealing. Flash lamp annealed selenium-implanted silicon shows a substitutional fraction of ~ 70% with an implanted concentration up to 2.3%. The resistivity is lower and the carrier mobility is higher than those of nanosecond pulsed laser annealed samples. Our results show that flash-lamp annealing is superior to laser annealing in preventing surface segregation and in allowing scalability. PMID:25660096

  1. Preparation of carbon blacks by liquid phase plasma (LPP) process.

    PubMed

    Yun, Kang-Seop; Kim, Bo-Ra; Kang, Woo-Seung; Jung, Sang-Chul; Myung, Seung-Taek; Kim, Sun-Jae

    2013-11-01

    In this study, carbon black nanoparticles were synthesized by Liquid Phase Plasma (LPP) technique; plasma generated in the organic solvent of benzene at 4.9 kV with the pulse frequency of 15 kHz and width of 5 micros transformed the carbon atoms in the solvent into carbon blacks by oxidation and reduction reactions. Graphite phase was found to be introduced into the carbon blacks without any additional processes due to the characteristics of LPP process, resulting in a higher G/D ratio of 0.92, compared to 0.83 of commercial Ketjen carbon blacks. For the performance improvement, heat treatment was employed and its parameters such as temperature and duration time were optimized in relation to the crystallinity and specific surface area of the carbon blacks. Carbon blacks heat treated at 450 degrees C in the air for 20 min were measured to have the discharge capacity of 1750 mAh/g and irreversible charging and discharging capacity ratio of 52.6%. PMID:24245259

  2. Liquid phase deposition synthesis of hexagonal molybdenum trioxide thin films

    SciTech Connect

    Deki, Shigehito; Beleke, Alexis Bienvenu; Kotani, Yuki [Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokko, Nada, Kobe 657-8501 (Japan); Mizuhata, Minoru, E-mail: mizuhata@kobe-u.ac.j [Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokko, Nada, Kobe 657-8501 (Japan)

    2009-09-15

    Hexagonal molybdenum trioxide thin films with good crystallinity and high purity have been fabricated by the liquid phase deposition (LPD) technique using molybdic acid (H{sub 2}MoO{sub 4}) dissolved in 2.82% hydrofluoric acid (HF) and H{sub 3}BO{sub 3} as precursors. The crystal was found to belong to a hexagonal hydrate system MoO{sub 3}.nH{sub 2}O (napprox0.56). The unit cell lattice parameters are a=10.651 A, c=3.725 A and V=365.997 A{sup 3}. Scanning electron microscope (SEM) images of the as-deposited samples showed well-shaped hexagonal rods nuclei that grew and where the amount increased with increase in reaction time. X-ray photon electron spectroscopy (XPS) spectra showed a Gaussian shape of the doublet of Mo 3d core level, indicating the presence of Mo{sup 6+} oxidation state in the deposited films. The deposited films exhibited an electrochromic behavior by lithium intercalation and deintercalation, which resulted in coloration and bleaching of the film. Upon dehydration at about 450 deg. C, the hexagonal MoO{sub 3}.nH{sub 2}O was transformed into the thermodynamically stable orthorhombic phase. - Abstract: SEM photograph of typical h-MoO{sub 3}.nH{sub 2}O thin film nuclei obtained after 36 h at 40 deg. C by the LPD method. Display Omitted

  3. Hyperdoping silicon with selenium: solid vs. liquid phase epitaxy

    NASA Astrophysics Data System (ADS)

    Zhou, Shengqiang; Liu, Fang; Prucnal, S.; Gao, Kun; Khalid, M.; Baehtz, C.; Posselt, M.; Skorupa, W.; Helm, M.

    2015-02-01

    Chalcogen-hyperdoped silicon shows potential applications in silicon-based infrared photodetectors and intermediate band solar cells. Due to the low solid solubility limits of chalcogen elements in silicon, these materials were previously realized by femtosecond or nanosecond laser annealing of implanted silicon or bare silicon in certain background gases. The high energy density deposited on the silicon surface leads to a liquid phase and the fast recrystallization velocity allows trapping of chalcogen into the silicon matrix. However, this method encounters the problem of surface segregation. In this paper, we propose a solid phase processing by flash-lamp annealing in the millisecond range, which is in between the conventional rapid thermal annealing and pulsed laser annealing. Flash lamp annealed selenium-implanted silicon shows a substitutional fraction of ~ 70% with an implanted concentration up to 2.3%. The resistivity is lower and the carrier mobility is higher than those of nanosecond pulsed laser annealed samples. Our results show that flash-lamp annealing is superior to laser annealing in preventing surface segregation and in allowing scalability.

  4. Liquid phase deposition of silica: Thin films, colloids and fullerenes

    NASA Astrophysics Data System (ADS)

    Whitsitt, Elizabeth A.

    Little research has been done to explore liquid phase deposition (LPD) of silica on non-planar substrates. This thesis proves that the seeded growth of silica colloids from fullerene and surfactant micelles is possible via LPD, as is the coating of individual single walled carbon nanotubes (SWNTs) and carbon fibers. Working on the premise that a molecular growth mechanism (versus colloidal/gel deposition) is valid for LPD, nanostructured substrates and specific chemical functional groups should act as "seeds," or templates, for silica growth. Seeded growth is confirmed by reactions of the growth solution with a range of surfactants and with materials with distinctive surface moieties. LPD promises lower production costs and environmental impact as compared to present methods of coating technology, because it is an inherently simple process, using low temperatures and inexpensive air-stable reactants. Silica is ubiquitous in materials science. Its applications range from thixotropic additives for paint to gate dielectrics in the semiconductor industry. Nano-structured coatings and thin films are integral in today's electronics industry and will become more vital as the size of electronics shrinks. With the incorporation of nanoparticles in future devices, the ability to deposit quality coatings with finely tuned properties becomes paramount. The methods developed herein have applications in fabricating insulators for use in the future molecular scale electronics industry. Additionally, these silica nanoparticles have applications as templates for use in photonics and fuel cell membrane production and lend strength and durability to composites.

  5. Liquid-phase synthesis of cobalt oxide nanoparticles.

    PubMed

    Sinkó, Katalin; Szabó, Géza; Zrínyi, Miklós

    2011-05-01

    Various liquid-phase syntheses of CoO and Co3O4 nanoparticles have been studied. The experiments focus on two synthesis routes: the coprecipitation and the sol-gel methods combined with thermal decomposition. The effect of synthesis route, the type of precursors (cobalt nitrate/chloride) and precipitation agent (carbonate, hydroxide, oxalic acid, and ammonia), the chemical compositions, pH, application of surfactants (PDMS, Triton X-100, NaDS, NaDBS, TTAB, ethyl acetate, citric acid), and the heat treatments on the properties of particles were investigated. The particle size and distribution have been determined by dynamic light scattering (DLS). The phases and the morphology of products have been analysed by XRD and SEM. The coprecipitation technique is less able to shape the particles than sol-gel technique. PDMS can be applied efficiently as surfactant in preparation methods. The finest particles (around 85 nm) with narrow polydispersity (70-100 nm) and spherical shape could be achieved by using sol-gel technique in medium of 1-propanol and ethyl acetate. PMID:21780416

  6. Analysis of liquid-phase chemical detection using guided shear horizontal-surface acoustic wave sensors.

    PubMed

    Li, Zhonghui; Jones, Yolanda; Hossenlopp, Jeanne; Cernosek, Richard; Josse, Fabien

    2005-07-15

    Direct chemical sensing in liquid environments using polymer-guided shear horizontal surface acoustic wave sensor platforms on 36 degrees rotated Y-cut LiTaO3 is investigated. Design considerations for optimizing these devices for liquid-phase detection are systematically explored. Two different sensor geometries are experimentally and theoretically analyzed. Dual delay line devices are used with a reference line coated with poly (methyl methacrylate) (PMMA) and a sensing line coated with a chemically sensitive polymer, which acts as both a guiding layer and a sensing layer or with a PMMA waveguide and a chemically sensitive polymer. Results show the three-layer model provides higher sensitivity than the four-layer model. Contributions from mass loading and coating viscoelasticity changes to the sensor response are evaluated, taking into account the added mass, swelling, and plasticization. Chemically sensitive polymers are investigated in the detection of low concentrations (1-60 ppm) of toluene, ethylbenzene, and xylenes in water. A low-ppb level detection limit is estimated from the present experimental measurements. Sensor properties are investigated by varying the sensor geometries, coating thickness combinations, coating properties, and curing temperature for operation in liquid environments. Partition coefficients for polymer-aqueous analyte pairs are used to explain the observed trend in sensitivity for the polymers PMMA, poly(isobutylene), poly(epichlorohydrin), and poly(ethyl acrylate) used in this work. PMID:16013878

  7. Supercritical phenomenon of hydrogen beyond the liquid–liquid phase transition

    NASA Astrophysics Data System (ADS)

    Li, Renzhong; Chen, Ji; Li, Xinzheng; Wang, Enge; Xu, Limei

    2015-06-01

    Using ab initio molecular dynamics simulation, we investigate the supercritical phenomenon associated with the liquid–liquid phase transition of hydrogen by studying the isothermal response functions, such as electric conductivity, molecular dissociation coefficient and isothermal compressibility, with respect to pressure. We find that, along each isotherm in the supercritical region, each of these response functions shows a maximum, the location of which is different for different response functions. As temperature decreases, the loci of these maxima asymptotically converge to a line of zero ordering field, known as the Widom line along which the magnitude of the response function maxima becomes larger and larger until it diverges as the critical point is approached. Thus, our study provides a possible way to locate the liquid–liquid critical point of hydrogen from the supercritical region at lower pressures. It also indicates that the supercritical phonomenon near the critical point of hydrogen is a rather general feature of second-order phase transition, it is not only true for classical systems with weak interactions but also true for highly condensed system with strong inter-atomic interactions.

  8. Liquid Phase Micro-Extraction of Linear Alkylbenzene Sulfonate Anionic Surfactants in Aqueous Samples

    PubMed Central

    Larsson, Niklas; Otrembska, Paulina; Villar, Mercedes; Jönsson, Jan Åke

    2011-01-01

    Hollow fiber liquid phase micro-extraction (LPME) of linear alkylbenzene sulfonates (LAS) from aqueous samples was studied. Ion pair extraction of C10, C11, C12 and C13 homologues was facilitated with trihexylamine as ion-pairing agent, using di-n-hexylether as solvent for the supported liquid membrane (SLM). Effects of extraction time, acceptor buffer concentration, stirring speed, sample volume, NaCl and humic acids were studied. At 10–50 ?g L?1 linear R2-coefficients were 0.99 for C10 and C11 and 0.96 for C12. RSD was typically ?15%. Three observations were especially made. Firstly, LPME for these analytes was unusually slow with maximum enrichment observed after 15–24 h (depending on sample volume). Secondly, the enrichment depended on LAS sample concentration with 35–150 times enrichment below ?150 ?g L?1 and 1850–4400 times enrichment at 1 mg L?1. Thirdly, lower homologues were enriched more than higher homologues at low sample concentrations, with reversed conditions at higher concentrations. These observations may be due to the fact that LAS and the amine counter ion themselves influence the mass transfer at the water-SLM interface. The observations on LPME of LAS may aid in LPME application to other compounds with surfactant properties or in surfactant enhanced membrane extraction of other compounds. PMID:24957870

  9. Equilibrium partial pressures and mean activity and osmotic coefficients of 0-100% nitric acid as a function of temperature

    Microsoft Academic Search

    Simon L. Clegg; Peter. Brimblecombe

    1990-01-01

    Rational activity and osmotic coefficients and Henry's law constants K{sub Hx} (for the reaction HNO{sub 3(g)} = H{sup +}{sub (aq)} + NOâ⁻{sub (aq)}), given as functions of temperature, enable p(HâO) and p(HNOâ) to be calculated from -60 to 120°C, 0-100% HNOâ. Apparent molal enthalpies, heat capacities, and activity coefficients (derived from electromotive force (emf), freezing point, and partial pressure data)

  10. A new method for multicomponent activity coefficients of electrolytes in aqueous atmospheric aerosols

    NASA Astrophysics Data System (ADS)

    Zaveri, Rahul A.; Easter, Richard C.; Wexler, Anthony S.

    2005-01-01

    Three-dimensional models of atmospheric inorganic aerosols need accurate and computationally efficient parameterizations of activity coefficients of various electrolytes in multicomponent aqueous solutions. In this paper, we extend the Taylor's series expansion mixing rule used by C. Wagner in 1952 for estimating activity coefficients in dilute alloy solutions to aqueous electrolyte solutions at any concentration. The resulting method, called the multicomponent Taylor expansion method (MTEM), estimates the mean activity coefficient of an electrolyte in a multicomponent solution on the basis of its values in binary solutions of all the electrolytes present in the mixture at the solution water activity aw, assuming aw is equal to the ambient relative humidity. MTEM is applied here for atmospheric aerosol systems containing H+, NH4+, Na+, Ca2+, SO42-, HSO4-, NO3-, and Cl- ions. The aerosol water content is calculated using the Zdanovskii-Stokes-Robinson (ZSR) method. For self-consistency, most of the MTEM and ZSR parameters are derived using the comprehensive Pitzer-Simonson-Clegg model at 298.15 K and are valid for an aw range of 0.2-0.97. Because CaSO4 is sparingly soluble, it is treated as a solid in the model over the entire aw range. MTEM is evaluated for several multicomponent systems representing various continental and marine aerosols and is contrasted against the mixing rule of C. L. Kusik and H. P. Meissner and of L. A. Bromley and the newer approach of S. Metzger and colleagues. Predictions of MTEM are found to be generally within a factor of 0.8-1.25 of the comprehensive Pitzer-Simonson-Clegg model and are shown to be significantly more accurate than predictions of the other three methods. MTEM also yields a noniterative solution of the bisulfate ion dissociation in sulfate-rich systems: a major computational advantage over other ionic-strength-based methods that require an iterative solution. CPU time requirements of MTEM relative to other methods for sulfate-poor and sulfate-rich systems are also discussed.

  11. Great Plains ASPEN Model Development: binary interaction parameters and activity coefficient parameters. Final report

    SciTech Connect

    Stern, S.S.; Millman, M.C.; Kirman, J.J.; Nwogu, D.

    1984-12-01

    The simulation of the various sections of the Great Plains Coal Gasification Plant involves modelling vapor-liquid equilibria and liquid-liquid equilibria that are highly nonideal. The Peng-Robinson equation of state, modified for water, was used in the simulation of most of the process sections. Interaction parameters established by regression of literature data, using ASPEN's DRS system, along with interaction parameter values found in the literature, became the database for the simulation. In two of the sections, the Oxygen Plant and the TEG drying of the product SNG, activity coefficient models were used because they gave a better prediction of the phase equilibrium. For the Rectisol unit, which removes hydrogen sulfide from the gas, parameters available from a DOE sponsored contract, Tristate, were used, after verification, for the ASPEN modified version of the RKS. The phases that were predicted using these parameters were checked against literature data and, in most cases, the liquid mole fractions of carbon dioxide predicted by the correlation were within 10% of those reported. A model that would predict phase equilibrium, based on the ionization of Lewis acids and bases and salts, would have been an ideal choice for simulation of the Stretford and Phosam flowsheets. However, only limited temperature dependent liquid activity coefficients data are available in the literature for the ionic species found in the Stretford and Phosam solutions, from which correlation parameters could be obtained by regression. Also, only the flash model can handle this type of calculation; therefore, it was used only to a limited extent in the simulation of the Stretford Unit Absorber. 118 references.

  12. Transient liquid-phase infiltration of a powder-metal skeleton

    E-print Network

    Lorenz, Adam Michael, 1974-

    2002-01-01

    Transient Liquid-Phase Infiltration (TLI) is a new method for densifying a powder-metal skeleton that produces a final part of homogeneous composition without significant dimensional change, unlike traditional infiltration ...

  13. Compositional effects on the liquid-phase sintering of praseodymium oxide-based zinc oxide varistors

    SciTech Connect

    Alles, A.B.; Puskas, R.; Callahan, G.; Burdick, V.L. (Alfred Univ., NY (United States). New York State Coll. of Ceramics)

    1993-08-01

    The influence of the formation of eutectic liquid phases during sintering of the ternary varistor system ZnO-Pr[sub 6]O[sub 11]-Co[sub 3]O[sub 4] was studied. The temperature at which the samples were observed to be liquid-phase sintered was found to depend on the nominal batch composition. The appearance of the liquid phase had a significant effect on the final microstructure as well as on the electrical properties of the varistors. Small additions of ZrO[sub 2], purposely added or resoluting from ball-mill contamination, were found to affect moderately the properties of the liquid phases observed in this system.

  14. Mathematical Modeling and Numerical Simulation of Liquid-Solid and Solid-Liquid Phase Change

    E-print Network

    Joy, Aaron

    2013-08-31

    This thesis presents numerical simulations of liquid-solid and solid-liquid phase change processes using mathematical models in Lagrangian and Eulerian descriptions. The mathematical models are derived by assuming a smooth interface (or transition...

  15. Use of free silicon in liquid phase sintering of silicon nitrides and sialons

    DOEpatents

    Raj, Rishi (Ithaca, NY); Baik, Sunggi (Ithaca, NY)

    1985-11-12

    This invention relates to the production of improved high density nitrogen based ceramics by liquid-phase densification of silicon nitride or a compound of silicon-nitrogen-oxygen-metal, e.g. a sialon. In the process and compositions of the invention minor amounts of finely divided silicon are employed together with the conventional liquid phase producing additives to enhance the densification of the resultant ceramic.

  16. Use of free silicon in liquid phase sintering of silicon nitrides and sialons

    DOEpatents

    Raj, R.; Baik, S.

    1985-11-12

    This invention relates to the production of improved high density nitrogen based ceramics by liquid-phase densification of silicon nitride or a compound of silicon-nitrogen-oxygen-metal, e.g. a sialon. In the process and compositions of the invention minor amounts of finely divided silicon are employed together with the conventional liquid phase producing additives to enhance the densification of the resultant ceramic. 4 figs.

  17. Direct observation of liquid-phase sintering in the system tungsten carbide-cobalt

    Microsoft Academic Search

    Leonard Froschauer; Richard M. Fulrath

    1976-01-01

    The hot-stage of a scanning electron microscope has been used to observe liquid-phase sintering in the system tungsten carbide-cobalt.\\u000a Densification behaviour and the mechanism for the first, fast stage of sintering have been determined; the influence of particle\\u000a size and the amount of liquid phase has been investigated. In all samples the densification kinetics is that of a rearrangement\\u000a process;

  18. Liquid-phase deposition of single-phase alpha-copper-indium-diselenide

    Microsoft Academic Search

    J. Cowen; L. Lucas; F. Ernst; P. Pirouz; A. Hepp; S. Bailey

    2005-01-01

    Based on the first complete Cu–In–Se phase diagram, which was recently established, we propose a new method for making single-phase copper-indium-diselenide (CuInSe2) films for high-specific-power photovoltaic applications: “liquid-phase deposition.” Contrary to established methods, in particular physical vapor deposition, liquid-phase deposition operates close to thermodynamic equilibrium and should therefore yield films with a smaller concentration of defects and better photovoltaic performance.

  19. Ultrasound promoted catalytic liquid-phase dehydrogenation of isopropanol for Isopropanol-Acetone-Hydrogen chemical heat pump.

    PubMed

    Xu, Min; Xin, Fang; Li, Xunfeng; Huai, Xiulan; Liu, Hui

    2015-03-01

    The apparent kinetic of the ultrasound assisted liquid-phase dehydrogenation of isopropanol over Raney nickel catalyst was determined in the temperature range of 346-353 K. Comparison of the effects of ultrasound and mechanical agitation on the isopropanol dehydrogenation was investigated. The ultrasound assisted dehydrogenation rate was significantly improved when relatively high power density was used. Moreover, the Isopropanol-Acetone-Hydrogen chemical heat pump (IAH-CHP) with ultrasound irradiation, in which the endothermic reaction is exposure to ultrasound, was proposed. A mathematical model was established to evaluate its energy performance in term of the coefficient of performance (COP) and the exergy efficiency, into which the apparent kinetic obtained in this work was incorporated. The operating performances between IAH-CHP with ultrasound and mechanical agitation were compared. The results indicated that the superiority of the IAH-CHP system with ultrasound was present even if more than 50% of the power of the ultrasound equipment was lost. PMID:25246094

  20. Transient liquid phase bonding of ferritic oxide dispersion strengthened alloys

    NASA Astrophysics Data System (ADS)

    Krishnardula, Venu Gopal

    2006-04-01

    Oxide dispersion strengthened (ODS) alloys possess excellent properties including resistance to oxidation, corrosion, creep and thermal fatigue. In addition, ferritic ODS alloys exhibit resistance to void swelling and are of particular interest to the nuclear industry. The present study involves the joining of fuel cans to end caps that will be utilized in the nuclear industry. Mechanically alloyed (MA) ODS alloys possess coarse columnar grain structure strengthened with nanosize yttria dispersoids. In that past, fusion welding techniques resulted in microstructural disruption leading to poor joints. This work investigated joining of two ferritic MA ODS alloys, MA956 and PM2000, using; (a) Transient liquid phase (TLP) bonding and (b) Solid-state diffusion bonding. TLP bonds were prepared with MA956 and PM2000 in the unrecrystallized and recrystallized conditions using electron beam physical vapor deposited (EBPVD) boron thin films as interlayers. The use of thin interlayers reduced the amount of substrate dissolution and minimized the bondline microstructural disruption. Different bond orientations were also investigated. Successful bonds with better microstructural continuity were obtained when substrates were joined in the unrecrystallized condition followed by post bond recrystallization heat treatment with the substrate faying surface aligned along the working (extrusion or rolling) direction than when substrates were aligned perpendicular to the working direction. This was attributed to the number of yttria stringers cut by the bondline, which is less when the substrate faying surface is lying parallel to the working direction than when the substrate faying surface is lying perpendicular to the working direction. Solid-state diffusion bonding was conducted using MA956 and PM2000 in the unrecrystallized and recrystallized conditions. Bonding occurred only when an unrecrystallized substrate was involved. Bonding occurred at unusually low stresses. This may be attributed to the grain boundary diffusion, owing to submicron grain size of the unrecrystallized substrates. Post bond heat treatment was conducted in order to induce recrystallization in the bonds. Room temperature mechanical testing was conducted on the bonds and the bulk. Bond shear strengths and tensile strengths of up to 80% and 110% of bulk, respectively, were obtained. Defects in the bulk material such as porosity and unwanted fine grain formation were observed. Pore formation at the bondline during post bond heat treatment seems to decrease the bond strength. These defects were attributed to prior thermomechanical history of the materials.

  1. Dynamic changes of integrated backscatter, attenuation coefficient and bubble activities during high-intensity focused ultrasound (HIFU) treatment.

    PubMed

    Zhang, Siyuan; Wan, Mingxi; Zhong, Hui; Xu, Cheng; Liao, Zhenzhong; Liu, Huanqing; Wang, Supin

    2009-11-01

    This paper simultaneously investigated the transient characteristics of integrated backscatter (IBS), attenuation coefficient and bubble activities as time traces before, during and after HIFU treatment, with different HIFU parameters (acoustic power and duty cycle) in both transparent tissue-mimicking phantoms and freshly excised bovine livers. These dynamic changes of acoustic parameters and bubble activities were correlated with the visualization of lesion development selected from photos, conventional B-mode ultrasound images and differential IBS images over the whole procedure of HIFU treatment. Two-dimensional radiofrequency (RF) data were acquired by a modified diagnostic ultrasound scanner to estimate the changes of mean IBS and attenuation coefficient averaged in the lesion region, and to construct the differential IBS images and B-mode ultrasound images simultaneously. Bubble activities over the whole procedure of HIFU treatment were investigated by the passive cavitation detection (PCD) method and the changes in subharmonic and broadband noise were correlated with the transient characteristics of IBS and attenuation coefficient. When HIFU was switched on, IBS and attenuation coefficient increased with the appearance of bubble clouds in the B-mode and differential IBS image. At the same time, the level of subharmonic and broadband noise rose abruptly. Then, there was an initial decrease in the attenuation coefficient, followed by an increase when at lower HIFU power. As the lesion appeared, IBS and attenuation coefficient both increased rapidly to a value twice that of normal. Then the changes in IBS and attenuation coefficient showed more complex patterns, but still showed a slower trend of increases with lesion development. Violent bubble activities were visible in the gel and were evident as strongly echogenic regions in the differential IBS images and B-mode images simultaneously. This was detected by a dramatic high level of subharmonic and broadband noise at the same time. These bubble activities caused fluctuations in IBS and attenuation coefficient during HIFU treatment. After HIFU, IBS and attenuation coefficient decreased gradually accompanied by the fadeout of bright hyperechoic spot in the B-mode and differential IBS image, but were still higher than normal when they were stable. The increases of IBS and attenuation coefficient were greater when using higher acoustic power or a higher duty cycle of the therapeutic emission. These experiments indicated that the bubble activities had the dominant effects on the transient characteristics of IBS and attenuation. This should be taken into consideration when using the dynamic acoustic-property changes for the potentially real-time monitoring imaging of HIFU treatment. PMID:19716225

  2. Activity coefficients of actinide and rare-earth chlorides in molten LiCl/KCl eutectic salt

    SciTech Connect

    Bechtel, T.B.; Storvick, T.S. [Univ. of Missouri, Columbia, MO (United States). Dept. of Chemical Engineering] [Univ. of Missouri, Columbia, MO (United States). Dept. of Chemical Engineering

    1999-04-01

    Using a numerical Gibbs free-energy minimization technique, the activity coefficients of actinide and rare-earth chlorides in molten LiCl/KCl eutectic at 450 C have been calculated. Laboratory tests of an electrochemical process for separating actinide metals from rare-earth metals in LiCl/KCl solvent at 450 C provided experimental concentration and cathode potential data. The generalized expansion by Wohl was used to express the concentration dependence of the excess Gibbs free energy. The activity coefficients were expressed in terms of the Wohl volume and interaction energy parameters. The Wohl parameters for the activity coefficient expansions were obtained by minimizing the total Gibbs free energy expressed in terms of the experimental mole fractions. This thermodynamic model will be valuable for process design and scale-up calculations.

  3. Biodegradation of 4-chlorophenol by acclimated and unacclimated activated sludge-Evaluation of biokinetic coefficients

    SciTech Connect

    Sahinkaya, Erkan [Department of Environmental Engineering, Middle East Technical University, Inonu Bulvari, 06531 Ankara (Turkey); Dilek, Filiz B. [Department of Environmental Engineering, Middle East Technical University, Inonu Bulvari, 06531 Ankara (Turkey)]. E-mail: fdilek@metu.edu.tr

    2005-10-01

    Unacclimated and acclimated activated sludges were examined for their ability to degrade 4-CP (4-chlorophenol) in the presence and absence of a readily growing substrate using aerobic batch reactors. The effects of 4-CP on the {mu} (specific growth rate), COD removal efficiency, Y (yield coefficient), and q (specific substrate utilization rate) were investigated. It was observed that the toxicity of 4-CP on the culture decreased remarkably after acclimation. For example, the IC{sub 50} value on the basis of {mu} was found to increase from 130 to 218mg/L with the acclimation of the culture. Although an increase in 4-CP concentration up to 300mg/L has no adverse effect on the COD removal efficiency of the acclimated culture, a considerable decrease was observed in the case of an unacclimated culture. Although 4-CP removal was not observed with an unacclimated culture, almost complete removal was achieved with the acclimated culture, up to 300mg/L. The Haldane kinetic model adequately predicted the biodegradation of 4-CP and the kinetic constants obtained were q{sub m}=41.17mg/(gMLVSSh), K{sub s}=1.104mg/L, and K{sub i}=194.4mg/L. The degradation of 4-CP led to formation of 5-chloro-2-hydroxymuconic semialdehyde, which was further metabolized, indicating complete degradation of 4-CP via a meta-cleavage pathway.

  4. Differential liquid phase proteomic analysis of the effect of selenium supplementation in LNCaP cells.

    PubMed

    Roveri, Antonella; Vitale, Maria Pia; Serain, Elena; Zaccarin, Mattia; Mauri, Pierluigi; Di Silvestre, Dario; De Palma, Antonella; Gion, Massimo; Toppo, Stefano; Maiorino, Matilde; Ursini, Fulvio

    2008-04-01

    The effect of 100 nM sodium selenite supplementation was studied on LNCaP cells by a proteomic approach, on ProteomeLab PF 2D platform. Proteins were separated by liquid phase bi-dimensional chromatography and analyzed by pair-wise alignment of peaks to detect those differentially expressed. Differential expression threshold was set at a twice difference level and proteins matching this criterion were identified by MALDI-TOF and confirmed by ESI-ion trap MS/MS. Not all differentially expressed proteins found by PF 2D could be identified by MS analysis, the sensitivity of which emerging as the limiting factor. Thus, only the most abundant proteins, differently expressed following selenium supplementation, were identified. We positively showed an increase of expression of thioredoxin reductase 1, enolase 1, phosphoglycerate mutase 1, glyceraldehyde-3-phosphate dehydrogenase, heterogeneous nuclear ribonucleoprotein A2/B1, isoform A2, Ras-GTPase-activating protein SH3-domain-binding protein and Keratin 18 and a decrease of expression of peroxiredoxin 1 and heat shock protein 70, protein 8, isoform 1. Results are consistent, at least in part, with the less oxidant environment brought about by the synthesis of Se-dependent peroxidases, keeping low the steady-state concentration of hydrogen peroxide. PMID:18329347

  5. Partial transient liquid phase diffusion bonding of Zircaloy-4 to stabilized austenitic stainless steel 321

    SciTech Connect

    Atabaki, M. Mazar, E-mail: m.mazaratabaki@gmail.com [Department of Materials Engineering, Faculty of Mechanical Engineering, University Technology Malaysia, 81310 (Malaysia); Hanzaei, A. Talebi [Department of Metallurgy and Materials Engineering, Faculty of Engineering, University of Tehran (Iran, Islamic Republic of)

    2010-10-15

    An innovative method was applied for bonding Zircaloy-4 to stabilized austenitic stainless steel 321 using an active titanium interlayer. Specimens were joined by a partial transient liquid phase diffusion bonding method in a vacuum furnace at different temperatures under 1 MPa dynamic pressure of contact. The influence of different bonding temperatures on the microstructure, microindentation hardness, joint strength and interlayer thickness has been studied. The diffusion of Fe, Cr, Ni and Zr has been investigated by scanning electron microscopy and energy dispersive spectroscopy elemental analyses. Results showed that control of the heating and cooling rate and 20 min soaking at 1223 K produces a perfect joint. However, solid-state diffusion of the melting point depressant elements into the joint metal causes the solid/liquid interface to advance until the joint is solidified. The tensile strength of all the bonded specimens was found around 480-670 MPa. Energy dispersive spectroscopy studies indicated that the melting occurred along the interface of the bonded specimens as a result of the transfer of atoms between the interlayer and the matrix during bonding. This technique provides a reliable method of bonding zirconium alloy to stainless steel.

  6. Water Detritiation: Better SCK-CEN Catalysts for Liquid Phase Catalytic Exchange

    SciTech Connect

    Bruggeman, Aime; Braet, Johan; Vanderbiesen, Sven [SCK-CEN (Belgium)

    2005-07-15

    A technically and economically sound technology for water detritiation is mandatory for the future of fusion. This technology is expected to be based on water electrolysis and Liquid Phase Catalytic Exchange (LPCE). LPCE requires an efficient hydrophobic catalyst. SCK-CEN invented and developed such a catalyst in the past, which is prepared by depositing platinum on an activated charcoal carrier and mixing it with polytetrafluorethylene as a hydrophobic material. In combination with an appropriate wettable packing, different batches of this catalyst performed very well during years of extensive testing, allowing us to develop the ELEX process for water detritiation at inland reprocessing plants. Recently we succeeded in reproducing this catalyst and preparing a slightly different but clearly ameliorated type. By extrapolation these new results would allow us to obtain, at 40 deg. C and under typical but conservative operating conditions, a decontamination factor of 10000 with a column of less than 3 meters long. Such performances would make this catalyst an excellent candidate for application at JET or ITER. To confirm the performances of our improved catalyst for a longer period of time and in a longer column, we are now starting experiments in a newly built installation and we are collaborating with ICSI, Romania.

  7. Rapid destruction of the rhodamine B using TiO2 photocatalyst in the liquid phase plasma

    PubMed Central

    2013-01-01

    Background Rhodamine B (RhB) is widely used as a colorant in textiles and food stuffs, and is also a well-known water tracer fluorescent. It is harmful to human beings and animals, and causes irritation of the skin, eyes and respiratory tract. The carcinogenicity, reproductive and developmental toxicity, neurotoxicity and chronic toxicity toward humans and animals have been experimentally proven. RhB cannot be effectively removed by biological treatment due to the slow kinetics. Therefore, RhB is chosen as a model pollutant for liquid phase plasma (LPP) treatment in the present investigation. Results This paper presents experimental results for the bleaching of RhB from aqueous solutions in the presence of TiO2 photocatalyst with LPP system. Properties of generated plasma were investigated by optical emission spectroscopy methods. The results of electrical-discharge degradation of RhB showed that the decomposition rate increased with the applied voltage, pulse width, and frequency. The oxygen gas addition to reactant solution increases the degradation rate by active oxygen species. The RhB decomposition rate was shown to increase with the TiO2 particle dosage. Conclusion This work presents the conclusions on the photocatalytic oxidation of RhB, as a function of plasma conditions, oxygen gas bubbling as well as TiO2 particle dosage. We knew that using the liquid phase plasma system with TiO2 photocatalyst at high speed we could remove the organic matter in the water. PMID:24041151

  8. Solid-liquid phase equilibrium for binary Lennard-Jones mixtures

    NASA Astrophysics Data System (ADS)

    Hitchcock, Monica R.; Hall, Carol K.

    1999-06-01

    Solid-liquid phase diagrams are calculated for binary mixtures of Lennard-Jones spheres using Monte Carlo simulation and the Gibbs-Duhem integration technique of Kofke. We calculate solid-liquid phase diagrams for the model Lennard-Jones mixtures: argon-methane, krypton-methane, and argon-krypton, and compare our simulation results with experimental data and with Cottin and Monson's recent cell theory predictions. The Lennard-Jones model simulation results and the cell theory predictions show qualitative agreement with the experimental phase diagrams. One of the mixtures, argon-krypton, has a different phase diagram than its hard-sphere counterpart, suggesting that attractive interactions are an important consideration in determining solid-liquid phase behavior. We then systematically explore Lennard-Jones parameter space to investigate how solid-liquid phase diagrams change as a function of the Lennard-Jones diameter ratio, ?11/?22, and well-depth ratio, ?11/?22. This culminates in an estimate of the boundaries separating the regions of solid solution, azeotrope, and eutectic solid-liquid phase behavior in the space spanned by ?11/?22 and ?11/?22 for the case ?11/?22<0.85.

  9. Gamma-ray spectra of hexane in gas phase and liquid phase

    E-print Network

    Xiaoguang Ma; Feng Wang

    2012-11-01

    Theoretical gamma-ray spectra of molecule hexane have been calculated and compared with the experimental results in both gas (Surko et al, 1997) and liquid (Kerr et al, 1965) phases. The present study reveals that in gas phase not all valence electrons of hexane exhibit the same probability to annihilate a positron. Only the positrophilic electrons in the valence space dominate the gamma-ray spectra, which are in good agreement with the gas phase measurement. When hexane is confined in liquid phase, however, the intermolecular interactions ultimately eliminate the free molecular orientation and selectivity for the positrophilic electrons in the gas phase. As a result, the gamma-ray spectra of hexane become an averaged contribution from all valence electrons, which is again in agreement with liquid phase measurement. The roles of the positrophilic electrons in annihilation process for gas and liquid phases of hexane have been recognized for the first time in the present study.

  10. Biofilm thickness measurement using an ultrasound method in a liquid phase.

    PubMed

    Maurício, R; Dias, C J; Jubilado, N; Santana, F

    2013-10-01

    In this report, the development of an online, noninvasive, measurement method of the biofilm thickness in a liquid phase is presented. The method is based in the analysis of the ultrasound wave pulse-echo behavior in a liquid phase reproducing the real reactor conditions. It does not imply the removal of the biomass from the support or any kind of intervention in the support (pipes) to detect and perform the measurements (non-invasiveness). The developed method allows for its sensor to be easily and quickly mounted and unmounted in any location along a pipe or reactor wall. Finally, this method is an important innovation because it allows the thickness measurement of a biofilm, in liquid phase conditions that can be used in monitoring programs, to help in scheduling cleaning actions to remove the unwanted biofilm, in several application areas, namely in potable water supply pipes. PMID:23494195

  11. Commercial-Scale Demonstration of the Liquid Phase Methanol (LPMEOH) Process

    SciTech Connect

    None

    1998-12-21

    he Liquid Phase Methanol (LPMEOW) Demonstration Project at Kingsport Tennessee, is a $213.7 million cooperative agreement between the U.S. Department of Energy (DOE) and Air Products Liquid Phase Conversion Company, L.P. (the Partnership) to produce methanol from coal-derived synthesis gas (syngas). Air Products and Chemicals, Inc. (Air Products) and Eastman Chemical Company (Eastman) formed the Partnership to execute the Demonstration Project. The LPMEOEP Process Demonstration Unit was built at a site located at the Eastman coal-to-chemicals complex in Kingsport. The LPMEOHW Demonstration Facility completed its first year of operation on 02 April 1998. The LPMEOW Demonstration Facility also completed the longest continuous operating run (65 days) on 21 April 1998. Catalyst activity, as defined by the ratio of the rate constant at any point in time to the rate constant for freshly reduced catalyst (as determined in the laboratory autoclave), was monitored throughout the reporting period. During a six-week test at a reactor temperature of 225oC and Balanced Gas flowrate of 700 KSCFH, the rate of decline in catalyst activity was steady at 0.29-0.36% per day. During a second one-month test at a reactor temperature of 220oC and a Balanced Gas flowrate of 550-600 KSCFH, the rate of decline in catalyst activity was 0.4% per day, which matched the pefiorrnance at 225"C, as well as the 4-month proof-of-concept run at the LaPorte AFDU in 1988/89. Beginning on 08 May 1998, the LPMEOW Reactor temperature was increased to 235oC, which was the operating temperature tier the December 1997 restart with the fresh charge of catalyst (50'Yo of design loading). The flowrate of the primary syngas feed stream (Balanced Gas) was also increased to 700-750 KSCFH. During two stable operating periods between 08 May and 09 June 1998, the average catalyst deactivation rate was 0.8% per day. Due to the scatter of the statistical analysis of the results, this test was extended to better quanti& the catalyst aging behavior. During the reporting perio~ two batches of fresh catalyst were activated and transferred to the reactor (on 02 April and 20 June 1998). The weight of catalyst in the LPMEOW Reactor has reached 80% of the design value. At the end of the reporting period, a step-change in the pressure-drop profile within the LPMEOW Reactor and an increase in the pressure of the steam system which provides cooling to the LPMEOW Reactor were observed. No change in the calculated activity of the catalyst was detected during either of these transients. These parameters will be monitored closely for any additional changes.

  12. Activity Coefficients of HCl in the HCl + NH4Cl + H2O Systems at 298.15 and 313.15 K

    E-print Network

    Zhang, Luzheng

    Activity Coefficients of HCl in the HCl + NH4Cl + H2O Systems at 298.15 and 313.15 K Xiaoyan Ji electrolyte solution added continuously, the mean activity coefficients of HCl in the HCl + NH4Cl + H2O system. The activity coefficients of HCl in the HCl + NH4Cl + H2O system were measured experimentally at (293.15, 298

  13. Primitive model electrolytes. A comparison of the HNC approximation for the activity coefficient with Monte Carlo data

    E-print Network

    E. Gutiérrez-Valladares; M. Luksic; B. Millán-Malo; B. Hribar-Lee; V. Vlachy

    2012-02-20

    Accuracy of the mean activity coefficient expression (Hansen-Vieillefosse-Belloni equation), valid within the hypernetted chain (HNC) approximation, was tested in a wide concentration range against new Monte Carlo (MC) data for +1:-1 and +2:-2 primitive model electrolytes. The expression has an advantage that the excess chemical potential can be obtained directly, without invoking the time consuming Gibbs-Duhem calculation. We found the HNC results for the mean activity coefficient to be in good agreement with the machine calculations performed for the same model. In addition, the thermodynamic consistency of the HNC approximation was tested. The mean activity coefficients, calculated via the Gibbs-Duhem equation, seem to follow the MC data slightly better than the Hansen-Vieillefosse-Belloni expression. For completeness of the calculation, the HNC excess internal energies and osmotic coefficients are also presented. These results are compared with the calculations based on other theories commonly used to describe electrolyte solutions, such as the mean spherical approximation, Pitzer's extension of the Debye-H\\"uckel theory, and the Debye-H\\"uckel limiting law.

  14. Practical solid and liquid phase markers for studying gastric emptying in man

    SciTech Connect

    Thomforde, G.M.; Brown, M.L.; Malagelada, J.R.

    1985-03-01

    This paper presents a method used to evaluate solid and liquid phase markers for radionuclide gastric emptying studies. The authors conducted in vitro and in vivo comparative experiments employing several radiolabeled markers. Among the solid phase markers tested, Tc-99m-sulfur colloid in vivo-labeled liver and I-131-fiber performed optimally. However, Tc-99M sulfur colloid in scrambled egg showed very acceptable performance and it is significantly easier to prepare. Among liquid phase markers, they found In-111-DTPA stabilized with 1% albumin to be a good agent and appropriate for dual isotope emptying studies.

  15. Purification of inkjet ink from water using liquid phase, electric discharge polymerization and cellulosic membrane filtration.

    PubMed

    Jordan, Alexander T; Hsieh, Jeffery S; Lee, Daniel T

    2013-01-01

    A method to separate inkjet ink from water was developed using a liquid phase, electric discharge process. The liquid phase, electric discharge process with filtration or sedimentation was shown to remove 97% of inkjet ink from solutions containing between 0.1-0.8 g/L and was consistent over a range of treatment conditions. Additionally, particle size analysis of treated allyl alcohol and treated propanol confirmed the electric discharge treatment has a polymerization mechanism, and small molecule analysis of treated methanol using gas chromatography and mass spectroscopy confirmed the mechanism was free radical initiated polymerization. PMID:24225106

  16. Liquid Phase 3D Printing for Quickly Manufacturing Metal Objects with Low Melting Point Alloy Ink

    E-print Network

    Lei Wang; Jing Liu

    2014-02-25

    Conventional 3D printings are generally time-consuming and printable metal inks are rather limited. From an alternative way, we proposed a liquid phase 3D printing for quickly making metal objects. Through introducing metal alloys whose melting point is slightly above room temperature as printing inks, several representative structures spanning from one, two and three dimension to more complex patterns were demonstrated to be quickly fabricated. Compared with the air cooling in a conventional 3D printing, the liquid-phase-manufacturing offers a much higher cooling rate and thus significantly improves the speed in fabricating metal objects. This unique strategy also efficiently prevents the liquid metal inks from air oxidation which is hard to avoid otherwise in an ordinary 3D printing. Several key physical factors (like properties of the cooling fluid, injection speed and needle diameter, types and properties of the printing ink, etc.) were disclosed which would evidently affect the printing quality. In addition, a basic route to make future liquid phase 3D printer incorporated with both syringe pump and needle arrays was also suggested. The liquid phase 3D printing method, which owns potential values not available in a conventional modality, opens an efficient way for quickly making metal objects in the coming time.

  17. Solid and liquid phase equilibria in mixtures of N, N-dimethylacetamide with chlorinated hydrocarbons

    Microsoft Academic Search

    Guanquan Che; Wenlie Peng; Biao Che

    1997-01-01

    IN refs. [I, 21, we studied the solid and liquid phase equilibria in mixtures of tetrachloromethane with oxygen and nitrogen-containing compounds, intermolecular interactions with the formation of solid molecular addition compounds. The nitrogen atom linking with three carbon atoms is a strong electron donorr2], so is N, N-dimethylacetamide (DMA) . The chlorine atoms in chlorinated hydrocarbons are electron acceptors. DMA

  18. Effects of composition and sintering time on liquid phase sintered Co-Cu samples in microgravity

    Microsoft Academic Search

    Yubin He; Saiyin Ye; J. Naser; J. Chiang; J. E. Smith

    2000-01-01

    Twelve Co-Cu powder compact samples with different liquid volume fractions were processed during microgravity liquid phase sintering on a suborbital sounding rocket and three Space Shuttle missions. The processing times ranged from 2.5 minutes to 66 minutes. The samples exhibited dimension stability after sintering. Microstructural evolutions such as densification, dihedral angle, contact per grain and grain growth rates, indicated a

  19. Separation of Liquid Phases in Giant Vesicles of Ternary Mixtures of Phospholipids and Cholesterol

    Microsoft Academic Search

    Sarah L. Veatch; Sarah L. Keller

    2003-01-01

    We use fluorescence microscopy to directly observe liquid phases in giant unilamellar vesicles. We find that a long list of ternary mixtures of high melting temperature (saturated) lipids, low melting temperature (usually unsaturated) lipids, and cholesterol produce liquid domains. For one model mixture in particular, DPPC\\/DOPC\\/Chol, we have mapped phase boundaries for the full ternary system. For this mixture we

  20. Simplified thermodynamic functions for vapor-liquid phase separation and fountain effect pumps

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

    He-4 fluid handling devices near 2 K require novel components for non-Newtonian fluid transport in He II. Related sizing of devices has to be based on appropriate thermophysical property functions. The present paper presents simplified equilibrium state functions for porous media components which serve as vapor-liquid phase separators and fountain effect pumps.

  1. Characterization of Thermal Properties and Interface Development in Cu-In Liquid Phase

    E-print Network

    Collins, Gary S.

    Characterization of Thermal Properties and Interface Development in Cu-In Liquid Phase Sintered method for measuring thermal transmission properties for sample geometry and under vacuum ·Determine number DMR-1062898 and Intel Corporation. ApparatusObjectives ·Measure the effective thermal resistance

  2. Determination of Atmospheric Hydroxyl Radical by Liquid Phase Scrubbing and High Performance Liquid Chromatography

    Microsoft Academic Search

    Xiaohui Chen

    1995-01-01

    A new in situ method for determining atmospheric hydroxyl radical (OH) was developed. This method is based on liquid phase scrubbing technique and high performance liquid chromatography (LPS-HPLC). The sampling system employs glass bubblers to trap atmospheric OH into a buffered solution containing the chemical probe, salicylic acid (o-hydroxybenzoic acid, OHBA). The reaction of OHBA with OH produces a stable

  3. Degradation of phenol in water using a gas–liquid phase pulsed discharge plasma reactor

    Microsoft Academic Search

    Jie Li; Masayuki Sato; Takayuki Ohshima

    2007-01-01

    In this paper, a gas–liquid phase pulsed discharge plasma reactor was used to dispose phenol in aqueous solutions. The effect of pulsed peak voltage and energy, solution conductivity, solution pH, and additive gas varieties on degradation efficiency of phenol was reviewed in the research. The observed results showed that degradation efficiency of phenol increased with the increase of pulsed peak

  4. Dynamic digital speckle interferometry applied to optical diagnosis of gas-liquid phase change

    Microsoft Academic Search

    Yaozu Song; Hongling Zhang; Wei Zhang; Tianfeng Jiao

    2001-01-01

    In this paper, a Dynamic Digital Speckle Interferometry (DDSI) applied to optical diagnosis of gas-liquid phase change is proposed. The basic principle and experimental system of the DDSI are presented. This technology of flow optical diagnosis has the following three main advantages. First, DDSI uses a CCD camera as record device of a specklegram and a microcomputer, which processes the

  5. Transient liquid phase diffusion bonding and associated recrystallization phenomenon when joining ODS ferritic superalloys

    Microsoft Academic Search

    T. I. Khan; E. R. Wallach

    1996-01-01

    Oxide dispersion strengthened (ODS) ferritic superalloys attribute their excellent intermediate and high temperature creep resistant properties to the distribution of an inert oxide, Y2O3 within highly directional and elongated grains. Careful selection of joining techniques is, therefore, of utmost importance so that the parent metal microstructure is not disrupted and is continuous across the bond line. Transient liquid phase (TLP)

  6. Comparison of solid and liquid-phase bioassays using ecoscores to assess1 contaminated soils2

    E-print Network

    Paris-Sud XI, Université de

    1 Comparison of solid and liquid-phase bioassays using ecoscores to assess1 contaminated soils2 3 on aqueous and solid phases of contaminated soils were compared,18 belonging to a wide array of trophic) 2974-2981" DOI : 10.1016/j.envpol.2011.04.028 #12;2 four coke factory soils contaminated mainly

  7. New catalytic liquid-phase ammoxidation approach to the preparation of niacin (vitamin B3).

    PubMed

    Raja, Robert; Adams, Richard D; Blom, Douglas A; Pearl, William C; Gianotti, Enrica; Thomas, John Meurig

    2009-07-01

    New highly dispersed bimetallic nanoscale catalysts based on rhenium combined with antimony or bismuth have been shown to be highly effective for the ammoxidation of 3-picoline to nicotinonitrile (precursor for vitamin B3) under mild conditions in the liquid phase. PMID:19462987

  8. Direct applications of stabilized methanol from the liquid phase methanol (LPMEOH) process

    Microsoft Academic Search

    B. L. Bhatt; E. C. Heydorn; P. J. A. Tijm; R. M. Kornosky

    1999-01-01

    The Liquid Phase Methanol (LPMEOH) process uses a slurry bubble column reactor to convert synthesis (syngas) gas to methanol. Because of its superior heat management, the process can directly utilize the carbon monoxide (CO)-rich syngas characteristic of the gasification of coal, petroleum coke, residual oil, wastes, or other hydrocarbon feedstocks. When added to an integrated gasification combined cycle (IGCC) power

  9. Role of thermosolutal convection in liquid phase electroepitaxial growth of gallium arsenide

    Microsoft Academic Search

    N. Djilali; Z. Qin; S. Dost

    1995-01-01

    This article investigates the effect of thermosolutal convection in liquid phase electroepitaxial (LPEE) growth of GaAs through a two-dimensional numerical simulation model. The model accounts for heat transfer and electric current distribution with Peltier and Joule effects, diffusive and convective mass transport including the effect of electromigration, and fluid flow coupled with temperature and concentration fields. Simulations are performed for

  10. Examination of microstructural liquid phase behavior during heat treatment of doped -- lead telluride thermoelectric materials

    NASA Astrophysics Data System (ADS)

    Langan, Sean McCoy

    Thermoelectric materials offer a potentially valuable source of energy by converting a temperature gradient to electricity. Recent progress in alloying, doping, and nanostructuring these materials has increased their figure of merit, bringing this technology closer to widespread use. However, the costs associated with processing and questions about fatigue reliability during long-term use could slow the development process. Liquid phase microstructure shapes are critical for sintering; further understanding of these shapes could potentially be used to improve mechanical response and lower overall processing costs. Here we review our progress with respect to the microstructure development of the material depending on heat treatment and composition. Thermoelectric materials made up of a PbTe/Ag2Te system were produced by heat treatments aimed at producing a liquid phase in the material. These samples were then examined through scanning electron microscopy, in an attempt to better understand the microstructure and track the liquid phase. This study was met with mixed results. While the process outlined does seem to produce faster sintering than undoped samples, full densification was not achieved. Furthermore, though the silver telluride was identified in the sample through the use of backscattering detection and EDS, the desired accuracy in finding the liquid phase was not achieved. However, the silver telluride was found to penetrate the grain boundaries, create secondary phases and form nano-precipitates, a development that is extremely promising as these features could all scatter phonons and raise the figure of merit of the material.

  11. Stefan problem for a finite liquid phase and its application to laser or electron beam welding

    Microsoft Academic Search

    Tadashi Kasuya; Nobuyuki Shimoda

    1997-01-01

    An exact solution of a heat conduction problem with the effect of latent heat of solidification (Stefan problem) is derived. The solution of the one dimensional Stefan problem for a finite liquid phase initially existing in a semi-infinite body is applied to evaluate temperature fields produced by laser or electron beam welding. The solution of the model has not been

  12. Diffusional effects on the various stages of liquid-phase sintering in microgravity

    Microsoft Academic Search

    Saiyin Ye

    2002-01-01

    A metal powder compact endures dramatic changes in its microstructures and properties during the three stages of liquid phase sintering, such as solid dissolution, solid solution formation, Ostwald ripening, and particle agglomeration. All these changes are restricted by the rate of diffusion and gravity induced convection. Under the microgravity environment, the effect of diffusion is much more significant and its

  13. Temporal and spatial characterization of turbulent structures in liquid phase using POD technique

    NASA Astrophysics Data System (ADS)

    Munir, S.; Heikal, M. R.; Aziz, A. Rashid A.; Muthuvalu, M. S.; Siddiqui, M. I.

    2015-05-01

    The temporal and spatial structures of turbulent liquid phase (water) in pipelines were investigated. Two cases were considered one single liquid phase flow at 80 l/m, second slugy part of slug flow by introducing gas (compressed air) at 60 l/m while keeping liquid flow rate same. Particle image velocimetry (PIV) was used for quantitative measurement of two-dimensional instantaneous velocity of liquid phase. The overall effect of coherent structures on the dynamics of flow in liquid phase for both cases were studied by proper orthogonal decomposition (POD). POD technique was able to identify the structures and characterize them. Spatial and temporal modes were achieved for both cases. The dynamics of flow structure were quite changed with the introduction of gas phase for case II. For case I, the first two spatial modes contained 40% of the energy while for case II only first spatial contained the maximum energy. FFT analysis of temporal modes showed that the first temporal mode for case I has frequency 4.617 while for case II the first temporal mode has frequency 4.64Hz.

  14. Next generation materials for thermal interface and high density energy storage applications via liquid phase sintering

    Microsoft Academic Search

    J. Liu; P. Rottman; S. Dutta; P. Kumar; R. Raj; M. Renavikar; I. Dutta

    2009-01-01

    With the continuing increase in power dissipation requirements of electronic devices, there is a need to develop new thermal interface materials (TIM) with much higher thermal conductivity (K) than that available from conventional TIMs. Recently, liquid phase sintering (LPS) has been proposed as a new paradigm for designing next generation composite-solder TIMs with a radically different microstructure from those of

  15. Radiation hardness of fluorinated oxides prepared by liquid phase deposition method following rapid thermal oxidation

    Microsoft Academic Search

    Wei-Shin Lu; Jenq-Shiuh Chou; Si-Chen Lee; Jenn-Gwo Hwu

    1994-01-01

    Liquid phase deposition (LPD following rapid thermal oxidation 2 RTO) is proposed as a method to obtain the fluorinated gate oxides. The radiation effect on these fluorinated oxides prepared by various sequences is studied. It was experimentally observed that all the fluorinated gate oxides are more radiation hard than the rapid thermal oxide (control oxide). Interestingly, the amount of fluorine

  16. Reliable fluorinated thin gate oxides prepared by liquid phase deposition following rapid thermal process

    Microsoft Academic Search

    Wei-Shin Lu; Jenn-Gwo Hwu

    1996-01-01

    A reliable fluorinated thin gate oxide prepared by liquid phase deposition (LPD) following rapid thermal oxidation (RTO) in O2 or nitridation (RTN) in N2O ambient was reported. Fluorine (F) atoms incorporated into the oxides during LPD process are found to be helpful to the improvement of oxide quality. It is observed that these fluorinated gate oxides show good properties in

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

    SciTech Connect

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

    2012-07-30

    A large fraction of submicron atmospheric particles contains both organic material and inorganic salts. As the relative humidity cycles in the atmosphere, 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 semi-volatile organic compounds, the scattering and absorption of solar radiation, and the uptake of reactive gas species on atmospheric particles will be affected, with important implications for climate predictions. The actual occurrence of these types of phase transitions 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 observe the coexistence of two non-crystalline phases in particles generated from real-world samples collected on multiple days in Atlanta, Georgia, and in particles generated in the laboratory using atmospheric conditions. These results reveal that atmospheric particles can undergo liquid-liquid phase separations. Using a box model, we show that liquid-liquid phase separation can result in increased concentrations of gas-phase NO3 and N2O5 in the Atlanta region, due to decreased particle uptake of N2O5.

  18. Ionic liquid-based liquid phase microextraction with direct injection for capillary electrophoresis.

    PubMed

    Breadmore, Michael C

    2011-03-11

    Liquid-liquid microextraction using the water immiscible ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, EMIM NtfO?, for the concentration and cleanup of basic compounds for analysis by CE has been investigated. Using an electrolyte comprising 1 mol/L alanine and 3 mol/L acetic acid, EMIM NtfO? could be directly injected into the capillary after liquid phase extraction. Using the basic dye chryisoidine, sensitivity enhancements approaching 1000-fold were obtained by mixing 20 ?L of EMIM NtfO? with 1500 ?L of aqueous sample, leaving only 5 ?L of the undissolved ionic liquid which was used for injection into the CE. Lower more repeatable enhancement factors of 200-fold were obtained with slightly larger initial 25 ?L volumes of EMIM NtfO? due to the larger residual volume of ionic liquid which made handling easier. This could be extended to basic pharmaceuticals, and the extraction of clozapine and its two active metabolites, nor-clozapine and clozapine-N-oxide, was demonstrated from urine with enrichment factors greater than 100 obtained. Handling of potentially more dangerous samples, such as serum, through in-vial extraction of clozapine and its metabolites and direct injection of the ionic liquid layer was also demonstrated with enhancements in sensitivity of 80. Limits of detection from 3 to 11 ?g/L and 6 to 55 ?g/L were obtained from urine and serum, respectively, which are sufficiently low to be useful for the determination of these pharmaceuticals clinically for therapeutic drug monitoring and for forensic toxicology. PMID:21277579

  19. Liquid phase methanol LaPorte process development unit: Modification, operation, and support studies

    SciTech Connect

    Not Available

    1990-11-09

    As part of the liquid phase methanol process development program the present study evaluated adsorptive schemes to remove catalyst poisons from coal gas at pilot scale. In addition to a lab test with coal gas from Coolwater, two field tests were performed at Great Plains with live coal gas. In the lab with Coolwater, gas iron carbonyl, carbonyl sulfide,and hydrogen sulfide were effectively removed from the coal gas. The capacities of H-Y zeolite and BPL carbon for Fe(CO){sub 5} agreed well with the previous bench scale results at similar CO{sub 2} partial pressure. COS appeared to be chemisorbed on FCA carbon; its capacity was non-regenerable by hot nitrogen purge. A Cu/Zn catalyst, used to remove H{sub 2}S adsorptively, worked adequately. With the adsorption system on-line, a downstream methanol catalyst showed stable activity for 120 hours of operation. In the two field tests, it was demonstrated that the Great Plains (GP) syngas could be treated by adsorption for LPMEOH process. The catalyst deactivation observed in the first field test was much improved in the second field test after regular (every three days) regeneration of the adsorbents was practiced. The absorption system, which was designed for the removal of iron/nickel carbonyls, hydrogen/carbonyl sulfide and hydrochloric acid, needed to be modified to accommodate other unexpected impurities, such as acetonitrile and ethylene which were observed during both field tests. A lab test with a simulated GP gas indicated that low CO{sub 2} content (0.5%) in the GP gas does not cause catalyst deactivation. Adjusting the CO{sub 2} content of the feed to 5% by CO{sub 2} addition, increased methanol productivity by 40% in both the lab and the second field test. 6 refs., 25 figs., 14 tabs.

  20. Liquid-phase pulsed laser ablation and electrophoretic deposition for chalcopyrite thin-film solar cell application.

    PubMed

    Guo, Wei; Liu, Bing

    2012-12-01

    We report ligand-free synthesis of colloidal metallic nanoparticles using liquid-phase pulsed laser ablation, and electrophoretic deposition of the nanoparticles for fabrication of Cu(In,Ga)Se(2) (CIGS) thin film solar cells. First, colloidal metallic nanoparticles of Cu-In and Cu-Ga alloys are produced by pulsed laser ablation in common organic solvents without using stabilizing ligands. The nanoparticles are examined for phase, composition, and electrical surface charging and charge modulation mechanisms. Metallic precursor thin films with high purity and precise composition are produced by electrophoretic deposition of the colloids without transferring to another solvent and without using binders. Finally, we demonstrate fabrication of CIGS solar cells on Mo sheet substrates with an (active area) energy conversion efficiency up to 7.37%. PMID:23206317

  1. Extraterrestrial material analysis: loss of amino acids during liquid-phase acid hydrolysis

    NASA Astrophysics Data System (ADS)

    Buch, Arnaud; Brault, Amaury; Szopa, Cyril; Freissinet, Caroline

    2015-04-01

    Searching for building blocks of life in extraterrestrial material is a way to learn more about how life could have appeared on Earth. With this aim, liquid-phase acid hydrolysis has been used, since at least 1970 , in order to extract amino acids and other organic molecules from extraterrestrial materials (e.g. meteorites, lunar fines) or Earth analogues (e.g. Atacama desert soil). This procedure involves drastic conditions such as heating samples in 6N HCl for 24 h, either under inert atmosphere/vacuum, or air. Analysis of the hydrolyzed part of the sample should give its total (free plus bound) amino acid content. The present work deals with the influence of the 6N HCl hydrolysis on amino acid degradation. Our experiments have been performed on a standard solution of 17 amino acids. After liquid-phase acid hydrolysis (6N HCl) under argon atmosphere (24 h at 100°C), the liquid phase was evaporated and the dry residue was derivatized with N-Methyl-N-(t-butyldimethylsilyl)trifluoroacetamide (MTBSTFA) and dimethylformamide (DMF), followed by gas chromatography-mass spectrometry analysis. After comparison with derivatized amino acids from the standard solution, a significant reduction of the chromatographic peak areas was observed for most of the amino acids after liquid-phase acid hydrolysis. Furthermore, the same loss pattern was observed when the amino acids were exposed to cold 6N HCl for a short amount of time. The least affected amino acid, i.e. glycine, was found to be 73,93% percent less abundant compared to the non-hydrolyzed standard, while the most affected, i.e. histidine, was not found in the chromatograms after hydrolysis. Our experiments thereby indicate that liquid-phase acid hydrolysis, even under inert atmosphere, leads to a partial or total loss of all of the 17 amino acids present in the standard solution, and that a quick cold contact with 6N HCl is sufficient to lead to a loss of amino acids. Therefore, in the literature, the reported increase of the total quantity of amino acids after acid hydrolysis, due to the formation/release of amino acids during the whole water extraction / liquid-phase acid hydrolysis, could have hidden a loss of amino acids. Thus, in extraterrestrial material studies involving liquid-phase acid hydrolysis, the quantities of total amino acids may have been underestimated.

  2. Third-order gas-liquid phase transition and the nature of Andrews critical Tian Ma and Shouhong Wang

    E-print Network

    Wang, Shouhong

    Third-order gas-liquid phase transition and the nature of Andrews critical point Tian Ma-order gas-liquid phase transition and the nature of Andrews critical point Tian Ma1 and Shouhong Wang2 1 is to study the nature of the Andrews critical point in the gas-liquid transition in a physical

  3. Computer simulations of liquid silica: Equation of state and liquid-liquid phase transition Ivan Saika-Voivod,1

    E-print Network

    Sciortino, Francesco

    phase separation, in which two liquids of distinct chemical composition coexist, are com- mon the onset of liquid­liquid phase separation has been determined 13 , as well as a character- istic patternComputer simulations of liquid silica: Equation of state and liquid-liquid phase transition Ivan

  4. Binary Solid-Liquid Phase Diagram of Phenol and t-Butanol: An Undergraduate Physical Chemistry Experiment

    ERIC Educational Resources Information Center

    Xu, Xinhua; Wang, Xiaogang; Wu, Meifen

    2014-01-01

    The determination of the solid-liquid phase diagram of a binary system is always used as an experiment in the undergraduate physical chemistry laboratory courses. However, most phase diagrams investigated in the lab are simple eutectic ones, despite the fact that complex binary solid-liquid phase diagrams are more common. In this article, the…

  5. In situ evaluation of supersolidus liquid phase sintering phenomena of stainless steel 316L: Densification and distortion

    Microsoft Academic Search

    Ravi Bollina

    2005-01-01

    Supersolidus liquid phase sintering (SLPS) is a variant of liquid phase sintering. In SLPS, prealloyed powders are heated between the solidus and liquidus temperature of the alloy. This thesis focuses on processing of stainless steel 316L via SLPS by adding boron. Various amounts of boron were added to study the effect of boron on densification and distortion. The sintering window

  6. Mixture distribution and flame propagation in a heavy-duty liquid petroleum gas engine with liquid phase injection

    Microsoft Academic Search

    S Oh; C Bae

    2004-01-01

    Enhanced mixture preparation by liquid phase injection on to the port could promote the application of liquefied petroleum gas (LPG) in spark ignition (SI) engines. Mixture distribution and flame propagation of the liquid phase LPG injection (LPLI) engine with a large bore size were investigated in a single-cylinder optical engine which had optical accesses through both sides of the cylinder

  7. Activity coefficients at infinite dilution measurements for organic solutes and water in the ionic liquid 1-ethyl-3-methylimidazolium tetracyanoborate

    Microsoft Academic Search

    Urszula Doma?ska; Marta Królikowska; William E. Acree; Gary A. Baker

    2011-01-01

    The activity coefficients at infinite dilution, ?13?, for 36 solutes, including alkanes, cycloalkanes, alkenes, alkynes, aromatic hydrocarbons, alcohols, thiophene, tetrahydrofuran, ethers, acetone, and water, in the ionic liquid 1-ethyl-3-methylimidazolium tetracyanoborate, [EMIM][TCB], were determined by gas–liquid chromatography at temperatures from 298.15K to 358.15K. These values are compared to those previously published for selected solutes in the same ionic liquid. The values

  8. Liquid-liquid Phase Separation in Aerosols: Model Predictions, Laboratory and Field Observations

    NASA Astrophysics Data System (ADS)

    Zuend, A.; Seinfeld, J.

    2012-12-01

    Atmospheric aerosol particles composed of a variety of organic compounds, water, and dissolved inorganic ions exhibit changes in water content, phase state and mixing properties in response to variations in relative humidity (RH) and temperature of the environment. Liquid-liquid phase separation may occur in partially liquid aerosol particles as a consequence of changes in composition, most prominently water content. A liquid-liquid phase separation manifests the presence of limited miscibility among the solution constituents indicating significant non-ideality in the condensed phase, which is caused by unfavorable interactions between water molecules, inorganic ions, and organic compounds; especially in the presence of rather hydrophobic organics with low O:C atomic ratios. An increasing number of laboratory experiments and thermodynamic modeling studies suggest that liquid-liquid phase separation is expected to be present over a wide range of RH for typical organic:inorganic ratios of aged tropospheric aerosol. Recent data from field observations in the Los Angeles basin and other ambient observations, including droplet experiments from filter sample extracts, provide evidence for the presence of phase separations in ambient aerosol particles. We present an overview on liquid-liquid phase separation related to aerosols and organic-inorganic model systems based on thermodynamic theory, detailed calculations, laboratory experiments, and indirect evidence from field observations. There are several potentially important impacts of liquid-liquid phase separation on the distribution of semivolatile organic and inorganic compounds, the equilibration timescale of gas-particle partitioning, and consequences for particle-phase chemistry. We discuss important aspects related to the computational challenges and costs of predicting and representing phase separations in detailed physicochemical models and present a new algorithm designed for complex systems of many components.

  9. Simultaneous reconstruction of emission activity and attenuation coefficient distribution from TOF data, acquired with external transmission source.

    PubMed

    Panin, V Y; Aykac, M; Casey, M E

    2013-06-01

    The simultaneous PET data reconstruction of emission activity and attenuation coefficient distribution is presented, where the attenuation image is constrained by exploiting an external transmission source. Data are acquired in time-of-flight (TOF) mode, allowing in principle for separation of emission and transmission data. Nevertheless, here all data are reconstructed at once, eliminating the need to trace the position of the transmission source in sinogram space. Contamination of emission data by the transmission source and vice versa is naturally modeled. Attenuated emission activity data also provide additional information about object attenuation coefficient values. The algorithm alternates between attenuation and emission activity image updates. We also proposed a method of estimation of spatial scatter distribution from the transmission source by incorporating knowledge about the expected range of attenuation map values. The reconstruction of experimental data from the Siemens mCT scanner suggests that simultaneous reconstruction improves attenuation map image quality, as compared to when data are separated. In the presented example, the attenuation map image noise was reduced and non-uniformity artifacts that occurred due to scatter estimation were suppressed. On the other hand, the use of transmission data stabilizes attenuation coefficient distribution reconstruction from TOF emission data alone. The example of improving emission images by refining a CT-based patient attenuation map is presented, revealing potential benefits of simultaneous CT and PET data reconstruction. PMID:23648397

  10. Liquid phase epitaxial growth of GaAs

    SciTech Connect

    Wynne, D I [Univ. of California, Berkeley, CA (United States). Materials Science and Mineral Engineering

    1997-10-01

    Research into new semiconductor materials for measurement of electromagnetic radiation over a wide range of energies has been an active field for several decades. There is a strong desire to identify and develop new materials which can lead to improved detectors. Such devices are expected to solve problems that cannot be solved using the semiconductor materials and device structures which have been traditionally used for radiation detection. In order for a detector which is subjected to some type of irradiation to respond, the radiation must undergo an interaction with the detector. The net result of the radiation interaction in a broad category of detectors is the generation of mobile electric charge carriers (electrons and/or holes) within the detector active volume. This charge is collected at the detector contacts and it forms the basic electrical signal. Typically, the collection of the charge is accomplished through the imposition of an electric field within the detector which causes the positive and/or negative charges created by the radiation to flow in opposite directions to the contacts. For the material to serve as a good radiation detector, a large fraction (preferably 100%) of all carriers created by the interacting incident radiation must be collected. Charge trapping by deep level impurities and structural defects can seriously degrade detector performance. The focus of this thesis is on far infrared and X-ray detection. In X-ray detector applications of p-I-n diodes, the object is to measure accurately the energy distribution of the incident radiation quanta. One important property of such detectors is their ability to measure the energy of individual incident photons with high energy resolution.

  11. Liquid phase epitaxial growth and characterization of germanium far infrared blocked impurity band detectors

    SciTech Connect

    Bandaru, Jordana

    2001-05-12

    Germanium Blocked Impurity Band (BIB) detectors require a high purity blocking layer (< 10{sup 13} cm{sup -3}) approximately 1 mm thick grown on a heavily doped active layer ({approx} 10{sup 16} cm{sup -3}) approximately 20 mm thick. Epilayers were grown using liquid phase epitaxy (LPE) of germanium out of lead solution. The effects of the crystallographic orientation of the germanium substrate on LPE growth modes were explored. Growth was studied on substrates oriented by Laue x-ray diffraction between 0.02{sup o} and 10{sup o} from the {l_brace}111{r_brace} toward the {l_brace}100{r_brace}. Terrace growth was observed, with increasing terrace height for larger misorientation angles. It was found that the purity of the blocking layer was limited by the presence of phosphorus in the lead solvent. Unintentionally doped Ge layers contained {approx}10{sup 15} cm{sup -3} phosphorus as determined by Hall effect measurements and Photothermal Ionization Spectroscopy (PTIS). Lead purification by vacuum distillation and dilution reduced the phosphorus concentration in the layers to {approx} 10{sup 14} cm{sup -3} but further reduction was not observed with successive distillation runs. The graphite distillation and growth components as an additional phosphorus source cannot be ruled out. Antimony ({approx}10{sup 16} cm{sup -3}) was used as a dopant for the active BIB layer. A reduction in the donor binding energy due to impurity banding was observed by variable temperature Hall effect measurements. A BIB detector fabricated from an Sb-doped Ge layer grown on a pure substrate showed a low energy photoconductive onset ({approx}6 meV). Spreading resistance measurements on doped layers revealed a nonuniform dopant distribution with Sb pile-up at the layer surface, which must be removed by chemomechanical polishing. Sb diffusion into the pure substrate was observed by Secondary Ion Mass Spectroscopy (SIMS) for epilayers grown at 650 C. The Sb concentration at the interface dropped by an order of magnitude over {approx} 1.5 {micro}m. Layers grown at 550 C did not show significant Sb diffusion. Sn doped In{sub 2}O{sub 3} (ITO) was studied for use in far infrared transparent low temperature contacts for BIB arrays. It was found that {approx}100 nm of ITO deposited on Ge remains electrically conducting at 4 K and is {approx}90% transparent in the far infrared. ITO should be suitable for passivating contacts to Ge BIB arrays.

  12. Effect of Titanium Addition on the Thermal Properties of Diamond/Cu-Ti Composites Fabricated by Pressureless Liquid-Phase Sintering Technique

    PubMed Central

    Chung, Chih-Yu; Chu, Chao-Hung; Lee, Mu-Tse; Lin, Chun-Ming; Lin, Su-Jien

    2014-01-01

    In this study, minor-addition elements such as Si, Co, Cr, W, Mo, and Ti were added to matrix to improve the wettability between the diamonds and Cu matrix. The pressureless liquid-phase sintering technique adopted in this study provides a low-cost method for producing diamond/Cu composites with high potential for industrial mass production. Thermal properties of the diamond/Cu-Ti composites fabricated by pressureless liquid-phase sintering at 1373?K with variation in Ti contents were thoroughly investigated. XRD and TEM analysis show that TiC layer formed in the interface between Cu and diamond. The composites exhibited thermal conductivity as high as 620?W/m·K for 50?vol% diamond/Cu-0.6? at % Ti composite with diamond particle size of 300?µm. This value comes up to 85% of the thermal conductivity calculated by the Hasselman and Johnson (H-J) theoretical analysis. Under these conditions, a suitable coefficient of thermal expansion of 6.9?ppm/K was obtained. PMID:24715816

  13. Effect of titanium addition on the thermal properties of diamond/cu-ti composites fabricated by pressureless liquid-phase sintering technique.

    PubMed

    Chung, Chih-Yu; Chu, Chao-Hung; Lee, Mu-Tse; Lin, Chun-Ming; Lin, Su-Jien

    2014-01-01

    In this study, minor-addition elements such as Si, Co, Cr, W, Mo, and Ti were added to matrix to improve the wettability between the diamonds and Cu matrix. The pressureless liquid-phase sintering technique adopted in this study provides a low-cost method for producing diamond/Cu composites with high potential for industrial mass production. Thermal properties of the diamond/Cu-Ti composites fabricated by pressureless liquid-phase sintering at 1373 K with variation in Ti contents were thoroughly investigated. XRD and TEM analysis show that TiC layer formed in the interface between Cu and diamond. The composites exhibited thermal conductivity as high as 620 W/m · K for 50 vol% diamond/Cu-0.6 at % Ti composite with diamond particle size of 300 µm. This value comes up to 85% of the thermal conductivity calculated by the Hasselman and Johnson (H-J) theoretical analysis. Under these conditions, a suitable coefficient of thermal expansion of 6.9 ppm/K was obtained. PMID:24715816

  14. Liquid Phase 3D Printing for Quickly Manufacturing Metal Objects with Low Melting Point Alloy Ink

    E-print Network

    Wang, Lei

    2014-01-01

    Conventional 3D printings are generally time-consuming and printable metal inks are rather limited. From an alternative way, we proposed a liquid phase 3D printing for quickly making metal objects. Through introducing metal alloys whose melting point is slightly above room temperature as printing inks, several representative structures spanning from one, two and three dimension to more complex patterns were demonstrated to be quickly fabricated. Compared with the air cooling in a conventional 3D printing, the liquid-phase-manufacturing offers a much higher cooling rate and thus significantly improves the speed in fabricating metal objects. This unique strategy also efficiently prevents the liquid metal inks from air oxidation which is hard to avoid otherwise in an ordinary 3D printing. Several key physical factors (like properties of the cooling fluid, injection speed and needle diameter, types and properties of the printing ink, etc.) were disclosed which would evidently affect the printing quality. In addit...

  15. On the electrostrictive mechanism of nanosecond-pulsed breakdown in liquid phase

    NASA Astrophysics Data System (ADS)

    Seepersad, Yohan; Pekker, Mikhail; Shneider, Mikhail N.; Dobrynin, Danil; Fridman, Alexander

    2013-04-01

    In this study we have studied the initial stage of the nanosecond-pulsed discharge development in liquid phase. Modelling predicts that in the case of fast rising strong nonhomogeneous electric fields in the vicinity of high-voltage pin electrode a region saturated with nanoscale non-uniformities may be developed. This phenomenon is attributed to the electrostriction mechanisms and may be used to explain development of breakdown in liquid phase. In this work, schlieren method was used in order to demonstrate formation of negative pressure region in liquids with different dielectric permittivity constants: water, ethanol and ethanol-water mixture. It is shown that this density perturbation, formed at the raising edge of the high-voltage pulse, is followed by a generation of a shock wave propagating with the speed of sound away from the electrode, with negative pressure behind it.

  16. Stable non-Fermi liquid phase of itinerant spin-orbit coupled ferromagnets

    NASA Astrophysics Data System (ADS)

    Bahri, Yasaman; Potter, Andrew

    2015-03-01

    Direct coupling between gapless bosons and a Fermi surface results in the destruction of Landau quasiparticles and a breakdown of Fermi liquid theory. Such a non-Fermi liquid phase arises in spin-orbit coupled ferromagnets with spontaneously broken continuous symmetries due to strong coupling between rotational Goldstone modes and itinerant electrons. These systems provide an experimentally accessible context for studying non-Fermi liquid physics. Possible examples include low-density Rashba coupled electron gases, which have a natural tendency towards spontaneous ferromagnetism, or topological insulator surface states with proximity-induced ferromagnetism. Crucially, unlike the related case of a spontaneous nematic distortion of the Fermi surface, for which the non-Fermi liquid regime is expected to be masked by a superconducting dome, we show that the non-Fermi liquid phase in spin-orbit coupled ferromagnets is stable.

  17. Transient liquid phase bonding of a third generation gamma-titanium aluminum alloy: Gamma Met PX

    Microsoft Academic Search

    Daniel A. Butts

    2005-01-01

    The research work presented here discusses transient liquid phase (TLP) bonding of a current (i.e. third) generation gamma-TiAl alloy known as Gamma Met PX (GMPX). Effective implementation of GMPX in service is likely to require fabrication of complicated geometries for which a high performance metallurgical joining technique must be developed. Although a number of joining processes have been investigated, all

  18. The liquid-liquid phase transition in silicon revealed by snapshots of valence electrons

    PubMed Central

    Beye, Martin; Sorgenfrei, Florian; Schlotter, William F.; Wurth, Wilfried; Föhlisch, Alexander

    2010-01-01

    The basis for the anomalies of water is still mysterious. Quite generally tetrahedrally coordinated systems, also silicon, show similar thermodynamic behavior but lack—like water—a thorough explanation. Proposed models—controversially discussed—explain the anomalies as a remainder of a first-order phase transition between high and low density liquid phases, buried deeply in the “no man’s land”—a part of the supercooled liquid region where rapid crystallization prohibits any experimental access. Other explanations doubt the existence of the phase transition and its first-order nature. Here, we provide experimental evidence for the first-order-phase transition in silicon. With ultrashort optical pulses of femtosecond duration we instantaneously heat the electronic system of silicon while the atomic structure as defined by the much heavier nuclear system remains initially unchanged. Only on a picosecond time scale the energy is transferred into the atomic lattice providing the energy to drive the phase transitions. With femtosecond X-ray pulses from FLASH, the free-electron laser at Hamburg, we follow the evolution of the valence electronic structure during this process. As the relevant phases are easily distinguishable in their electronic structure, we track how silicon melts into the low-density-liquid phase while a second phase transition into the high-density-liquid phase only occurs after the latent heat for the first-order phase transition has been transferred to the atomic structure. Proving the existence of the liquid-liquid phase transition in silicon, the hypothesized liquid-liquid scenario for water is strongly supported. PMID:20805512

  19. Smart dielectrics of fluorinated silicon glass prepared by liquid phase deposition method

    Microsoft Academic Search

    Ching-Fa Yeh; Tien-Fu Chen; Yueh-Chuan Lee; Chien-Hung Liu; Shyue-Shyh Lin

    2001-01-01

    Fluorinated silicon glass (FSG) film prepared by using liquid-phase deposition (LPD) is very potential for use as a smart dielectric owing to its high fluorine concentration (8.6 at %), low dielectric constant (3.46), low stress (43 Mpa), low leakage current density (4.6E-9 A\\/cm2 at 2 MV\\/cm) and low deposition temperature (room temperature). By affecting the physicochemical properties and the electrical

  20. High dielectric constant nickel-doped titanium oxide films prepared by liquid-phase deposition

    NASA Astrophysics Data System (ADS)

    Lee, Ming-Kwei; Yen, Chih-Feng; Fan, Cho-Han

    2014-09-01

    The electrical characteristics of nickel-doped titanium oxide films prepared by liquid-phase deposition on p-type (100) silicon substrate were investigated. The aqueous solutions of ammonium hexafluorotitanate and boric acid were used as precursors for the growth of titanium oxide films and the dielectric constant is 29. The dielectric constant can be improved to 94 by nickel doping at the thermal annealing at 700 °C in nitrous oxide.

  1. Space cryogenics components based on the thermomechanical effect - Vapor-liquid phase separation

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

    Applications of the thermomechanical effect has been qualified including incorporation in large-scale space systems in the area of vapor-liquid phase separation (VLPS). The theory of the porous-plug phase separator is developed for the limit of a high thermal impedance of the solid-state grains. Extensions of the theory of nonlinear turbulent flow are presented based on experimental results.

  2. Experimental study of solid–liquid phase change in a spiral thermal energy storage unit

    Microsoft Academic Search

    J Banaszek; R Domañski; M Rebow; F El-Sagier

    1999-01-01

    A new idea on the use of a vertical spiral heat exchanger in a latent heat thermal energy storage system is analyzed experimentally. In this context, two important subjects are addressed. The first one is the temporal behavior of a phase change medium undergoing a non-isothermal solid–liquid phase change transition during its two-side heating or cooling by a working fluid

  3. Transient liquid phase bonding of ferritic oxide-dispersion-strengthened alloys

    Microsoft Academic Search

    Venu G. Krishnardula; Nofrijon I. Sofyan; William F. Gale; Jeffrey W. Fergus

    2006-01-01

    Joining of two ferritic oxide-dispersion-strengthened (ODS) alloys, MA956 and PM2000, using transient liquid phase (TLP) bonding\\u000a is discussed. Thin-film boron coatings of different thicknesses were used as interlayers and different bond orientations with\\u000a substrates cut along and normal to the direction of extrusion were studied, with postbond heat treatment and microscopic evaluation\\u000a of the bonds. Microstructural continuity was achieved in

  4. The kinetics of low-temperature liquid phase epitaxy in the Zn-Cd-Te system

    Microsoft Academic Search

    P. P. Moskvin; L. V. Rashkovetskii; F. F. Sizov

    2010-01-01

    The kinetic corrections for the supersaturation of the initial liquid phase providing the preparation of Zn\\u000a x\\u000a Cd1 ? x\\u000a Te solid solution layers at low deposition temperatures (500–600°C) were found. The results of kinetic modeling were in satisfactory\\u000a agreement with the experimental data. It was shown that the inclusion of corrections for supersaturation of the initial liquid\\u000a phase to

  5. A method of removing metal ions from silicate glasses for recycling by liquid-phase deposition

    Microsoft Academic Search

    Tetsuya Homma

    2001-01-01

    A method of removing metal ions from silicate glasses for recycling was studied. This method utilizes a liquid-phase deposition (LPD) technique using a hydrofluosilicic acid (H2SiF6) aqueous solution supersaturated with silica. Silicate glass powder prepared from a glass bottle was dissolved in aqueous hydrofluoric acid (HF) solution. The fluorinated silicon oxide (SiOF) separated from the H2SiF6, and then an LPD-SiOF

  6. Time dependent simulations of the growth of III–V crystals by the liquid phase electroepitaxy

    Microsoft Academic Search

    Zbigniew R. Zytkiewicz; Pawel Strak; Stanislaw Krukowski

    2011-01-01

    Results of time dependent simulations of growth of bulk binary III–V crystals by current controlled liquid phase electroepitaxy (LPEE) are reported using GaAs as an example. Without any electrical current the LPEE system is isothermal, kept at 1073K, thus no growth occurs. The electric current density of 10A\\/cm2 leads to ohmic heating of the entire system, Peltier cooling of the

  7. Hollow fiber-liquid-phase microextraction of fungicides from orange juices

    Microsoft Academic Search

    Francisco Barahona; Astrid Gjelstad; Stig Pedersen-Bjergaard; Knut Einar Rasmussen

    2010-01-01

    Liquid-phase microextraction (LPME) based on polypropylene hollow fibers was evaluated for the extraction of the post-harvest fungicides thiabendazole (TBZ), carbendazim (CBZ) and imazalil (IMZ) from orange juices. Direct LPME was performed without any sample pretreatment prior to the extraction, using a simple home-built equipment. A volume of 500?L of 840mM NaOH was added to 3mL of orange juice in order

  8. Solid-liquid phase diagrams for binary metallic alloys: Adjustable interatomic potentials

    Microsoft Academic Search

    H.-S. Nam; M. I. Mendelev; D. J. Srolovitz

    2007-01-01

    We develop an approach to determining Lennard-Jones embedded-atom method potentials for alloys and use these to determine the solid-liquid phase diagrams for binary metallic alloys using Kofke's Gibbs-Duhem integration technique combined with semigrand canonical Monte Carlo simulations. We demonstrate that it is possible to produce a wide range of experimentally observed binary phase diagrams (with no intermetallic phases) by reference

  9. Solid-liquid phase diagrams for binary metallic alloys: Adjustable interatomic potentials

    Microsoft Academic Search

    H.-S. Nam; M. I. Mendelev; D. J. Srolovitz

    2007-01-01

    We develop a new approach to determining LJ-EAM potentials for alloys and use\\u000athese to determine the solid-liquid phase diagrams for binary metallic alloys\\u000ausing Kofke's Gibbs-Duhem integration technique combined with semigrand\\u000acanonical Monte Carlo simulations. We demonstrate that it is possible to\\u000aproduce a wide-range of experimentally observed binary phase diagrams (with no\\u000aintermetallic phases) by reference to the

  10. Liquid phase sintering of an AA2014-based composite prepared from an elemental powder mixture

    Microsoft Academic Search

    J. Zhou; J. Duszczyk

    1999-01-01

    The AA2014 alloy reinforced with 10 vol% SiC particles has been prepared from elemental powders blended with the ceramic particles, instead of using a pre-alloyed atomized powder as the matrix material. Of critical importance in taking this uncommon processing route is liquid-phase sintering to transform the initial free aluminum and copper powder particles into the a-Al and the T-phase, thereby

  11. Fabrication of particle dispersed inert matrix fuel based on liquid phase sintered SiC

    Microsoft Academic Search

    D. Pavlyuchkov; R. H. Baney; J. S. Tulenko; H. J. Seifert

    2011-01-01

    In the present work, liquid phase sintered SiC (LPS-SiC) was proposed as an inert matrix for the particle dispersed inert matrix fuel (IMF). The fuel particles containing plutonium and minor actinides were substituted with pure yttria stabilized zirconia beads. The LPS-SiC matrix was produced from the initial mixtures prepared using submicron sized alpha-SiC powder and oxide additives Al2O3, Y2O3 in

  12. Fabrication of particle dispersed inert matrix fuel based on liquid phase sintered SiC

    Microsoft Academic Search

    D. Pavlyuchkov; R. H. Baney; J. S. Tulenko; H. J. Seifert

    2011-01-01

    In the present work, liquid phase sintered SiC (LPS-SiC) was proposed as an inert matrix for the particle dispersed inert matrix fuel (IMF). The fuel particles containing plutonium and minor actinides were substituted with pure yttria stabilized zirconia beads. The LPS-SiC matrix was produced from the initial mixtures prepared using submicron sized ?-SiC powder and oxide additives Al2O3, Y2O3 in

  13. Microporous hydrophobic hollow fiber modules for gas-liquid phase separation in microgravity

    Microsoft Academic Search

    Gary Noyes

    1993-01-01

    Gas-liquid interphase mass transfer operations, such as gas-liquid phase separation, gas absorption into liquid or dissolved gas separation from liquid, gas humidification and drying via liquid contact, and evaporative cooling are readily accomplished on the Earth with settling\\/spray chambers, packed towers, or bubble columns. This paper reports on gas-water mass transfer tests performed utilizing microporous hydrophobic Hollow Fiber Modules (HFMs)

  14. On the size dependences of the crystal-liquid phase transition parameters

    NASA Astrophysics Data System (ADS)

    Magomedov, M. N.

    2014-05-01

    A comparatively simple method is proposed for calculating the size dependences of the latent heat, volume jumps, and the interfacial surface energy for the crystal-liquid phase transition proceeding from the results of experiments (real or computer) on determining size dependences of the melting point and the crystallization temperature. The method is tested on the basis of computer simulation data for copper, gold, aluminum, and nickel nanoparticles and experimental data for tin.

  15. Solid-liquid phase equilibria of benzene + 2-methyl-2-propanol system under high pressures

    Microsoft Academic Search

    K. Nagaoka; T. Makita

    1988-01-01

    Solid-liquid phase equilibria of the benzene + 2-methyl-2-propanol system have been investigated at temperatures from 278 to 323 K and pressures up to 300 MPa using a high-pressure optical vessel. The uncertainties of the measurements of temperature, pressure and composition are within ±0.1 K, ±0.5 MPa, and ±0.001 mole fraction, respectively. The freezing pressure at a constant composition increases monotonously

  16. Counteraction of particulate segregation during transient liquid-phase bonding of aluminium-based MMC material

    Microsoft Academic Search

    Z. Li; Y. Zhou; T. H. North

    1995-01-01

    Particle segregation during transient liquid-phase bonding of aluminium-based metal matrix composite material using copper filler metal was investigated. Segregation was promoted by the slow movement of the solid-liquid interface during isothermal solidification and alumina particles with diameters less than 30 ?m were segregated when the copper foil thickness exceeded 5 and 15 ?m for the base metals examined. When bonding

  17. Optical properties of fluorinated silicon oxide films by liquid phase deposition for optical waveguides

    Microsoft Academic Search

    Tetsuya Homma; Atsushi Satoh; Seiji Okada; Masahiro Itoh; Masaki Yamaguchi; Hideo Takahashi

    1998-01-01

    Optical properties of fluorinated silicon oxide (SiOF) films for optical waveguide in optoelectronic devices were investigated. The SiOF films are formed at 25°C by a liquid phase deposition (LPD) technique using a supersaturated hydrofluosilicic acid (H2SiF 6) aqueous solution. Two main absorption peaks corresponding to Si-O and Si-F bonds were observed at the wavenumbers of 1090 and 930 cm-1 in

  18. Soot and liquid-phase fuel distributions in a newly designed optically accessible DI diesel engine

    NASA Astrophysics Data System (ADS)

    Dec, J. E.; Espey, C.

    1993-10-01

    Two-dimensional (2-D) laser-sheet imaging has been used to examine the soot and liquid-phase fuel distributions in a newly designed, optically accessible, direct-injection diesel engine of the heavy-duty size class. The design of this engine preserves the intake port geometry and basic dimensions of a Cummins N-series production engine. It also includes several unique features to provide considerable optical access. Liquid-phase fuel and soot distribution studies were conducted at a medium speed (1,200 rpm) using a Cummins closed-nozzle fuel injector. The scattering was used to obtain planar images of the liquid-phase fuel distribution. These images show that the leading edge of the liquid-phase portion of the fuel jet reaches a maximum length of 24 mm, which is about half the combustion bowl radius for this engine. Beyond this point virtually all the fuel has vaporized. Soot distribution measurements were made at a high load condition using three imaging diagnostics: natural flame luminosity, 2-D laser-induced incandescence, and 2-D elastic scattering. This investigation showed that the soot distribution in the combusting fuel jet develops through three stages. First, just after the onset of luminous combustion, soot particles are small and nearly uniformly distributed throughout the luminous region of the fuel jet. Second, after about 2 crank angle degrees a pattern develops of a higher soot concentration of larger sized particles in the head vortex region of the jet and a lower soot concentration of smaller sized particles upstream toward the injector. Third, after fuel injection ends, both the soot concentration and soot particle size increase rapidly in the upstream portion of the fuel jet.

  19. Deposition of gold nanoparticles on liquid phase epitaxy grown garnet films and Faraday rotation enhancement

    NASA Astrophysics Data System (ADS)

    Lang, G. S.; Bowen, D.; Krafft, C.; Mayergoyz, I. D.

    2013-05-01

    Plasmon resonance induced Faraday rotation enhancement in liquid phase epitaxy grown garnet films with gold nanoparticles on their surfaces is discussed. Experimental results are presented, which reveal stronger Faraday rotation enhancement for gold nanoparticles obtained by the annealing of thicker gold films evaporated on garnet film surfaces. This stronger Faraday rotation enhancement can be attributed to larger dimensions and separations of gold nanoparticles, which increase the extent of penetration of plasmon resonance induced electric fields into garnet films.

  20. Liquid phase thermochemical energy conversion systems - An application of Diels-Alder chemistry

    Microsoft Academic Search

    T. G. Lenz; L. S. Hegedus; J. D. Vaughan

    1982-01-01

    A method of thermochemical energy conversion, transport, and storage research involving moderate and low temperature liquid phase systems employing Diels-Alder cycloaddition chemistry is described. Proposed as a heat storage system for solar and industrial waste heat, the system involves the meeting, in a reactor, of energy-depleted and energy-rich fluids. The poor fluid gains energy and goes through a chemical, endothermic

  1. Use of the two-liquid phase concept to exploit kinetically controlled multistep biocatalysis.

    PubMed

    Bühler, Bruno; Bollhalder, Irene; Hauer, Bernhard; Witholt, Bernard; Schmid, Andreas

    2003-03-20

    The two-liquid phase concept was used to develop a whole cell biocatalytic system for the efficient multistep oxidation of pseudocumene to 3,4-dimethylbenzaldehyde. Recombinant Escherichia coli cells were employed to express the Pseudomonas putida genes encoding xylene monooxygenase, which catalyzes the multistep oxygenation of one methyl group of toluene and xylenes to corresponding alcohols, aldehydes, and acids. A fed-batch based two-liquid phase bioconversion was established with bis(2-ethylhexyl)- phthalate as organic carrier solvent and a phase ratio of 0.5; the product formation pattern, the impact of the nutrient feeding strategy, and the partitioning behavior of the reactants were studied. On the basis of the favorable conditions provided by the two-liquid phase system, engineering of the initial pseudocumene concentration allowed exploiting the complex kinetics of the multistep reaction for the exclusive production of 3,4-dimethyl- benzaldehyde. Further oxidation of the product to 3,4-dimethylbenzoic acid could be inhibited by suitable concentrations of pseudocumene or 3,4-dimethylbenzyl alcohol. The optimized biotransformation setup includes a completely defined medium with high iron content and a nutrient feeding strategy that avoids severe glucose limitation as well as high inhibitory glucose levels. Using such a system on a 2-liter scale, we were able to produce, within 14.5 h, 30 g of 3,4-dimethylbenzaldehyde as predominant reactant in the organic phase and reached a maximal productivity of 1.6 g per liter liquid volume per hour. The present study implicates that the two-liquid phase concept is an efficient tool to exploit the kinetics of multistep biotransformations in general. PMID:12529882

  2. Eutectic mixed monolayers in equilibrium with phospholipid-bilayers and triolein-liquid phase.

    PubMed Central

    Handa, T; Saito, H; Miyajima, K

    1993-01-01

    Triolein (TO) and phospholipids (egg yolk phosphatidylcholine, egg yolk phosphatidylethanolamine, and bovine brain phosphatidylserine) had low mutual solubilities and separated into the TO-liquid phase and phospholipid-bilayers. Spreading pressures of the TO-phospholipid mixture (i.e., surface pressures of the mixed monolayer in equilibrium with the phase-separating lipid mixture) at the air/saline interface were independent of the lipid composition. On the other hand, collapse pressures of the mixed monolayer of TO and phospholipid (i.e., surface pressures of the mixed monolayer in equilibrium with the TO-liquid phase) at the interface changed with the monolayer composition and were lower than the spreading pressure. The experimental data indicated the spreading and collapse pressures as offering a phase diagram for the presence of equilibrium between the mixed monolayer, the phospholipid-bilayers and the TO-liquid phase. The diagram showed that TO and the phospholipids were miscible in the mixed monolayer, forming an eutectic mixed monolayer. When the mixed monolayer initially had the eutectic composition, no collapse of the monolayer was detected until the surface pressure reached the value of the spreading pressure. No specific complex between TO and the phospholipid is required to explain the stability and collapse of the mixed monolayers. The bulk immiscibility of the lipids elucidated by the spreading pressure-measurements, immediately leads to the phase behaviors observed. PMID:8369406

  3. Balance of optical, structural, and electrical properties of textured liquid phase crystallized Si solar cells

    NASA Astrophysics Data System (ADS)

    Preidel, V.; Amkreutz, D.; Haschke, J.; Wollgarten, M.; Rech, B.; Becker, C.

    2015-06-01

    Liquid phase crystallized Si thin-film solar cells on nanoimprint textured glass substrates exhibiting two characteristic, but distinct different surface structures are presented. The impact of the substrate texture on light absorption, the structural Si material properties, and the resulting solar cell performance is analyzed. A pronounced periodic substrate texture with a vertical feature size of about 1 ?m enables excellent light scattering and light trapping. However, it also gives rise to an enhanced Si crystal defect formation deteriorating the solar cell performance. In contrast, a random pattern with a low surface roughness of 45 nm allows for the growth of Si thin films being comparable to Si layers on planar reference substrates. Amorphous Si/crystalline Si heterojunction solar cells fabricated on the low-roughness texture exhibit a maximum open circuit voltage of 616 mV and internal quantum efficiency peak values exceeding 90%, resulting in an efficiency potential of 13.2%. This demonstrates that high quality crystalline Si thin films can be realized on nanoimprint patterned glass substrates by liquid phase crystallization inspiring the implementation of tailor-made nanophotonic light harvesting concepts into future liquid phase crystallized Si thin film solar cells on glass.

  4. Liquid-phase and solid-phase microwave irradiations for reduction of graphite oxide

    NASA Astrophysics Data System (ADS)

    Zhao, Na; Wen, Chen-Yu; Zhang, David Wei; Wu, Dong-Ping; Zhang, Zhi-Bin; Zhang, Shi-Li

    2014-12-01

    In this paper, two microwave irradiation methods: (i) liquid-phase microwave irradiation (MWI) reduction of graphite oxide suspension dissolved in de-ionized water and N, N-dimethylformamide, respectively, and (ii) solid-phase MWI reduction of graphite oxide powder have been successfully carried out to reduce graphite oxide. The reduced graphene oxide products are thoroughly characterized by scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectral analysis, Raman spectroscopy, UV-Vis absorption spectral analysis, and four-point probe conductivity measurements. The results show that both methods can efficiently remove the oxygen-containing functional groups attached to the graphite layers, though the solid-phase MWI reduction method can obtain far more efficiently a higher quality-reduced graphene oxide with fewer defects. The I(D)/I(G) ratio of the solid-phase MWI sample is as low as 0.46, which is only half of that of the liquid-phase MWI samples. The electrical conductivity of the reduced graphene oxide by the solid method reaches 747.9 S/m, which is about 25 times higher than that made by the liquid-phase method.

  5. Equilibrium partial pressures and mean activity and osmotic coefficients of 0-100% nitric acid as a function of temperature

    SciTech Connect

    Clegg, S.L. (Plymouth Marine Laboratory (England)); Brimblecombe, P. (Univ. of East Anglia, Norwich (England))

    1990-06-28

    Rational activity and osmotic coefficients and Henry's law constants K{sub Hx} (for the reaction HNO{sub 3(g)} = H{sup +}{sub (aq)} + NO{sub 3}{sup {minus}}{sub (aq)}), given as functions of temperature, enable p(H{sub 2}O) and p(HNO{sub 3}) to be calculated from {minus}60 to 120{degree}C, 0-100% HNO{sub 3}. Apparent molal enthalpies, heat capacities, and activity coefficients (derived from electromotive force (emf), freezing point, and partial pressure data) are represented with the use of the species-interaction models of Pitzer. Equations for the partial molal functions are given. The Henry's law constant is evaluated from p(HNO{sub 3}) data at 298.15 K, tabulated heats of formation, and heat capacities. Calculated p(H{sub 2}O) and p(HNO{sub 3}) over the entire concentration range agree with available data over 5 orders of magnitude of p(H{sub 2}O) and 7 orders of magnitude of p(HNO{sub 3}).

  6. A Microfluidic System for the Continuous Recycling of Unmodified Homogeneous Palladium Catalysts through Liquid/Liquid Phase Separation

    E-print Network

    Li, Pengfei

    A prototype microflow system for the continuous recycling of homogeneous catalysts through liquid/liquid phase separation was developed and its effectiveness demonstrated in a challenging palladium-catalyzed hydroxylation ...

  7. On Implicit Active Constraints in Linear Semi-Infinite Programs with Unbounded Coefficients

    SciTech Connect

    Goberna, M. A., E-mail: mgoberna@ua.es [Alicante University, Dep. of Statistics and Operations Research (Spain); Lancho, G. A., E-mail: lanchoga@mixteco.utm.mx [Universidad Tecnologica de Mixteca, Instituto de Fisica y Matematicas (Mexico); Todorov, M. I., E-mail: maxim.todorov@udlap.mx [UDLA, Dep. of Physics and Mathematics (Mexico); Vera de Serio, V. N., E-mail: vvera@uncu.edu.ar [Universidad Nacional de Cuyo, Facultad de Ciencias Economicas, Instituto de Ciencias Basicas (Argentina)

    2011-04-15

    The concept of implicit active constraints at a given point provides useful local information about the solution set of linear semi-infinite systems and about the optimal set in linear semi-infinite programming provided the set of gradient vectors of the constraints is bounded, commonly under the additional assumption that there exists some strong Slater point. This paper shows that the mentioned global boundedness condition can be replaced by a weaker local condition (LUB) based on locally active constraints (active in a ball of small radius whose center is some nominal point), providing geometric information about the solution set and Karush-Kuhn-Tucker type conditions for the optimal solution to be strongly unique. The maintaining of the latter property under sufficiently small perturbations of all the data is also analyzed, giving a characterization of its stability with respect to these perturbations in terms of the strong Slater condition, the so-called Extended-Nuernberger condition, and the LUB condition.

  8. Activity coefficients at infinite dilution for hydrocarbons in furfuryl alcohol at T=(278.15 and 298.15) K, determined by g.l.c

    Microsoft Academic Search

    Marta K. Koz?owska; Trevor M. Letcher; Urszula Doma?ska

    2004-01-01

    The potential of the polar solvent, furfuryl alcohol, as a solvent in the separation of aromatics from aliphatics and other hydrocarbons, has been investigated by measuring activity coefficients at infinite dilution. The activity coefficients at infinite dilution for some alkanes, cycloalkanes, alkenes, alkynes and benzene in furfuryl alcohol have been determined by g.l.c. at T=(278.15 and 298.15) K. The method

  9. Fluid Phase Equilibria 178 (2001) 259270 Mean activity coefficients in the NaClNH4HCO3H2O

    E-print Network

    Zhang, Luzheng

    2001-01-01

    Fluid Phase Equilibria 178 (2001) 259­270 Mean activity coefficients in the NaCl­NH4HCO3­H2O system The mean activity coefficients of NaCl in the NaCl­NH4HCO3­H2O system, measured by an electrochemical cell), the electromotive force (emf) method tends to be selected for the determination [2]. As far as the NaCl­NH4HCO3­H2O

  10. Ethers from ethanol. 1: Equilibrium thermodynamic analysis of the liquid-phase ethyl tert-butyl ether reaction

    Microsoft Academic Search

    Kyle L. Jensen; Ravindra Datta

    1995-01-01

    The equilibrium-limited liquid-phase synthesis of ethyl tert-butyl ether (ETBE) from the combination of ethanol and isobutylene over an ion-exchange resin catalyst, typically Amberlyst 15, is a reaction of considerable industrial importance now. An equilibrium constant relationship is developed here for the liquid-phase ETBE reaction by following three alternative thermodynamic pathways and critically evaluating the resulting expressions. The final theoretical expression

  11. Fuel effect on the liquid-phase penetration of an evaporating spray under transient diesel-like conditions

    Microsoft Academic Search

    J. V. Pastor; J. M. García-Oliver; J.-G. Nerva; B. Giménez

    2011-01-01

    Measurements of the maximum liquid-phase penetration have been performed injecting five different fuels through a single-hole nozzle in an optical engine under a large set of thermodynamic and injection conditions. The focus of this paper is twofold. First, it intends to study fuel physical properties on liquid-phase fuel penetration. The choice made on Fischer–Tropsch diesel (FTD) and biodiesel fuels has

  12. Preparation and performance of form-stable polyethylene glycol\\/silicon dioxide composites as solid–liquid phase change materials

    Microsoft Academic Search

    Weilong Wang; Xiaoxi Yang; Yutang Fang; Jing Ding

    2009-01-01

    This work mainly involved the preparation and characterization of form-stable polyethylene glycol (PEG)\\/silicon dioxide (SiO2) composite as a novel solid–liquid phase change material (PCM). In this study, the polyethylene glycol\\/silicon dioxide composites as form-stable, solid–liquid phase change material (PCM) was prepared. In this new material, the polyethylene glycol acts as the latent heat storage material and silicon dioxide serves as

  13. A versatile and compact experimental apparatus for the on-line spectroscopic study of liquid-phase heterogeneous catalytic systems

    Microsoft Academic Search

    Feng Gao; Kim Poi Ng; Chuanzhao Li; Karl I. Krummel; Ayman D. Allian; Marc Garland

    2006-01-01

    A versatile and compact experimental system is described for the study of fine-chemistry liquid-phase heterogeneous catalysis. The general experimental system consists of a stirred tank (25–100 mL), pump, tubular reactor, spectrometer(s), and injection block for liquid-phase perturbations, all in a closed-recycling configuration. The basic designs of the in-house-constructed components are provided. The system was characterized with respect to gas–liquid mass

  14. Prediction of Self-Diffusion Coefficients of Fluids Based on Friction and Free Volume Theories

    NASA Astrophysics Data System (ADS)

    Zhong, Qiu; Yang, Liping; Tao, Ye; Luo, Caiyun; Xu, Zijun; Xi, Tonggeng

    2015-05-01

    With a combination of friction and free volume theories, a new equation for calculating the self-diffusion coefficient is presented based on molecular dynamics simulation data in the literature. The equation could be applied to calculate the self-diffusion coefficient of real fluids in the gas or liquid phase. The equation was used to calculate the self-diffusion coefficients of 18 substances. The absolute average relative deviation was 13.79 %.

  15. Thermodynamic Relationships for Bulk Crystalline and Liquid Phases in the Phase-Field Crystal Model

    E-print Network

    Victor W. L. Chan; Nirand Pisutha-Arnond; Katsuyo Thornton

    2015-02-06

    We present thermodynamic relationships between the free energy of the phase-field crystal (PFC) model and thermodynamic state variables for bulk phases under hydrostatic pressure. This relationship is derived based on the thermodynamic formalism for crystalline solids of Larch\\'e and Cahn [Larch\\'e and Cahn, Acta Metallurgica, Vol. 21, 1051 (1973)]. We apply the relationship to examine the thermodynamic processes associated with varying the input parameters of the PFC model: temperature, lattice spacing, and the average value of the PFC order parameter, $\\bar{n}$. The equilibrium conditions between bulk crystalline solid and liquid phases are imposed on the thermodynamic relationships for the PFC model to obtain a procedure for determining solid-liquid phase coexistence. The resulting procedure is found to be in agreement with the method commonly used in the PFC community, justifying the use of the common-tangent construction to determine solid-liquid phase coexistence in the PFC model. Finally, we apply the procedure to an eighth-order-fit (EOF) PFC model that has been parameterized to body-centered-cubic ($bcc$) Fe [Jaatinen et al., Physical Review E 80, 031602 (2009)] to demonstrate the procedure as well as to develop physical intuition about the PFC input parameters. We demonstrate that the EOF-PFC model parameterization does not predict stable $bcc$ structures with positive vacancy densities. This result suggests an alternative parameterization of the PFC model, which requires the primary peak position of the two-body direct correlation function to shift as a function of $\\bar{n}$.

  16. Optoacoustic detection of a kinetic-cooling effect in the liquid phase.

    PubMed

    Park, S M; Shin, K B

    1995-11-20

    A kinetic-cooling effect in the liquid phase has been observed by the use of pulsed optoacoustic spectroscopy. The magnitude of the optoacoustic signal in an aqueous Eu(3+) solution, as measured from the absorption of pulsed light, was found to decrease when the excitation-laser wavelength was tuned to the transition from the thermally excited (7)F(1) state to the upper electronic (5)D(0) state of Eu(3+) ion. This anomalous optoacoustic phenomenon is attributed to the kinetic-cooling effect. PMID:21060642

  17. Mössbauer characterization of joints of steel pieces in transient liquid phase bonding experiences

    NASA Astrophysics Data System (ADS)

    di Luozzo, N.; Martínez Stenger, P. F.; Canal, J. P.; Fontana, M. R.; Arcondo, B.

    2011-11-01

    Joining of seamless, low carbon, steel tubes were performed by means of Transient Liquid Phase Bonding process employing a foil of Fe-Si-B metallic glass as filler material. The influence of the main parameters of the process was evaluated: temperature, holding time, pressure and post weld heat treatment. Powder samples were obtained from the joint of tubes and characterized employing Mössbauer Spectroscopy in transmission geometry. The sampling was performed both in tubes successfully welded and in those which show joint defects. The results obtained are correlated with the obtained microstructure and the diffusion of Si and B during the process.

  18. 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).

  19. Pinball liquid phase from Hund's coupling in frustrated transition-metal oxides

    NASA Astrophysics Data System (ADS)

    Ralko, Arnaud; Merino, Jaime; Fratini, Simone

    2015-04-01

    The interplay of nonlocal Coulomb repulsion and Hund's coupling in the d -orbital manifold in frustrated triangular lattices is analyzed by a multiband extended Hubbard model. We find a rich phase diagram with several competing phases, including a robust pinball liquid phase, which is an unconventional metal characterized by threefold charge order, bad metallic behavior, and the emergence of high-spin local moments. Our results naturally explain the anomalous charge-ordered metallic state observed in the triangular layered compound AgNiO2. The potential relevance to other triangular transition-metal oxides is discussed.

  20. Low temperature liquid-phase sintering in the magnesium aluminosilicate glass - alumina system

    NASA Astrophysics Data System (ADS)

    Nakajima, Akira

    This study was carried out to obtain a fundamental understanding of the process conditions and strategies for lowering liquid phase sintering temperatures. Alumina coated with 9 vol% of a ternary eutectic glass in the MgO-Alsb2Osb3-SiOsb2 (MAS) was used as the model system. Homogeneous coating of the glass was ensured by using a sol-gel coating technique. Sintering behavior of the glass coated alumina was investigated over a temperature range of 1400sp°C-1460sp°C. Mullite and spinel or sapphirine crystallized from the MAS liquid during sintering. The formation of spinel was observed at the interface between the liquid and alumina, whereas mullite was found to homogeneously crystallize in the liquid. The rate of glass crystallization was enhanced by finer powder. The time at which crystallization rate became significant corresponded to the onset of the decrease of densification rate at the temperature. Attaining a balance of these two competing phenomena at the sintering temperature is proposed as an additional criteria for successful liquid phase sintering at low temperatures. Additional experiments revealed that this balance is not easy to control in the case of bimodal powder mixture, and that homogeneous distribution of liquid at the initial stage is essential for the control of this balance. Densification kinetics and crystallization behavior of 0.2 mum alumina coated with boron or sodium doped glass in the MAS system were also investigated at 1400sp°C and 1460sp°C. Doping the Alsb2Osb3-MAS glass system is effective for liquid phase sintering of alumina at 1400sp°C. The balance between densification and crystallization for the alumina coated with MAS glass was altered by the addition of boron and sodium. However, the mechanisms by which boron and sodium improve the sintering kinetics are different. From the experimentally obtained result, the ratio of the densification rate to crystallization rate was calculated. Using theoretically determined equations and the analysis of above mentioned ratio, strategies to lower the temperature of liquid phase sintering was proposed.

  1. Hyphenating liquid phase separation techniques with mass spectrometry: on-line or off-line.

    PubMed

    Edwards, Emma; thomas-Oates, Jane

    2005-01-01

    The advantages of hyphenating analytical separation techniques to mass spectrometers have been recognised since the 1970s. The first attempts to couple liquid phase separations to mass spectrometry(MS) were problematic, but the development of electrospray ionisation (ES) in 1984 facilitated the production of routinely used, commercial interfaces. This review considers the most recent major developments in hyphenating liquid chromatographic and electrophoretic separations to mass spectrometry, and considers the role the post genomic sciences have played in driving them. It also considers why, despite all of the advances in hyphenation, the future appears to hold a major role for off-line analysis. PMID:15685782

  2. 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.

  3. Assessment of odor activity value coefficient and odor contribution based on binary interaction effects in waste disposal plant

    NASA Astrophysics Data System (ADS)

    Wu, Chuandong; Liu, Jiemin; Yan, Luchun; Chen, Haiying; Shao, Huiqi; Meng, Tian

    2015-02-01

    Odor activity value (OAV) has been widely used for the assessment of odor pollution from various sources. However, little attention has been paid to the extreme OAV variation and potential inaccuracies of odor contribution assessment caused by odor interaction effects. The objective of this study is to assess the odor interaction effect for precise assessment of odor contribution. In this paper, samples were collected from a food waste disposal plant, and analyzed by instrumental and olfactory method to conclude odorants' occurrence and OAV. Then odor activity value coefficient (?) was first proposed to evaluate the type and the level of binary interaction effects based on determination of OAV variation. By multiplying OAV and ?, odor activity factor (OAF) was used to reflect the real OAV. Correlation between the sum of OAF and odor concentration reached 80.0 ± 5.7%, which was 10 times higher than the sum of OAV used before. Results showed that hydrogen sulfide contributed most (annual average 66.4 ± 15.8%) to odor pollution in the waste disposal plant. However, as odor intensity of samples in summer rising, odor contribution of trimethylamine increased to 48.3 ± 3.7% by the strong synergistic interaction effect, while odor contribution of phenol decreased to 0.1 ± 0.02% for the increasing antagonistic interaction effect.

  4. Estimation of excess energies and activity coefficients for the penternary Ni-Cr-Co-Al-Mo system and its subsystems

    NASA Astrophysics Data System (ADS)

    Dogan, A.; Arslan, H.; Dogan, T.

    2015-06-01

    Using different prediction methods, such as the General Solution Model of Kohler and Muggianu, the excess energy and activities of molybdenum for the sections of the phase diagram for the penternary Ni-Cr-Co-Al-Mo system with mole ratios xNi/ xMo = 1, xCr/ xMo = 1, xCo/ xMo = 1, and xAl/ xMo = r = 0.5 and 1, were thermodynamically investigated at a temperature of 2000 K, whereas the excess energy and activities of Bi for the section corresponding to the ternary Bi-Ga-Sb system with mole ratio xGa/ xSb = 1/9 were thermodynamically investigated at a temperature of 1073 K. In the case of r = 0.5 and 1 in the alloys Ni-Cr-Co-Al-Mo, a positive deviation in the activity coefficient was revealed, as molybdenum content increased. Moreover, in the calculations performed in Chou's GSM model, the obtained values for excess Gibbs energies are negative in the whole concentration range of bismuth at 1073 K and exhibit the minimum of about -2.2 kJ/mol at the mole ratio xGa/ xSb = 1/9 in the alloy Bi-Ga-Sb.

  5. Electro-thermal treatment of high concentration ammonia in water by gaseous oxidation in liquid phase (GOLP).

    PubMed

    Cao, Limei; Yang, Ji; Jia, Jinping

    2010-06-01

    Gaseous oxidation in liquid phase (GOLP) process was proposed to degrade high concentration ammonium in water. The innovative concept behind the reactor design is that the monocrystalline silicon chip coated with catalyst could be heated instantaneously by direct current, which will gasify the surrounding ammonium solution and later catalytically convert it to harmless N(2). It is found out that Co(3)O(4) instead of Co(2)O(3) is the active catalytic component in the GOLP process and it coats the silicon chip evenly with nut-shell particle. The experimental results reveal that the GOLP process could degrade high concentration NH(4)(+) efficiently, in which when the current was 10A, the reactor could remove almost 98% NH(4)(+) after 2h treatment, at the initial concentration 1810mgL(-1). The overall GOLP process for de-nitrification could be presumed to have two steps: (1) the gasification of liquid around catalyst; and (2) catalytic conversion of NH(4)(+) to N(2), which is experimentally demonstrated by Ion Chromatography data. Also, the influences of current and pH were investigated to optimize the operating parameters for the GOLP reactor, and the preliminary energy consumption analysis based on lab data was provided for future reference. These results show that the GOLP process will be able to sustain without extra energy input theoretically if the ammonia concentration is higher than 1.48%. PMID:20462628

  6. Liquid-phase methanation/shift process development. First quarterly progress report, September 1-November 30, 1980

    SciTech Connect

    Not Available

    1981-01-20

    This program is a continuation of the Liquid Phase Methanation/Shift Program (EX-76-C-01-2036) which was completed on November 30, 1978. One of its primary goals is to study the rates of carbon formation during methanation over a wide range of process conditions and determine the effect of the carbon deposition on catalyst activity and selectivity. The second goal is to perform an engineering design of a hydrodynamic cold-flow unit of scale equivalent to the LPM/S pilot plant reactor for evaluation of the 3-phase reaction system hydrodynamics. Work to date has concentrated on the first task - Rates of Carbon Formation. The existing reaction units and analytical system have been refurbished and calibrated. Five nickel-based methanation catalysts were chosen as representative of the types available commercially. Carrier materials for the catalysts are alumina, kieselguhr and calcium aluminate. Nickel contents vary from 35 to 60% Ni. The first experimental scan, 100 hours - without steam, has been successfully completed. The second scan is in progress, 300 hours - without steam. Samples of both spent and virgin reduced catalysts have been sent out for analysis.

  7. Solar-chemical energy conversion via reversible liquid phase Diels-Alder reactions. Final technical report

    SciTech Connect

    Lenz, T.G.; Hegedus, L.S.; Vaughan, J.D.

    1983-05-01

    Thermochemical energy conversion at moderate or low temperature (< about 400/sup 0/C) employing liquid phase components throughout a cycle is suggested as a promising concept for high-efficiency conversion of solar energy to a convenient chemical form. In particular, we propose liquid phase Diels-Alder cycloaddition chemistry as an important class of reversible reactions for such low or moderate temperature thermochemical energy conversion systems. One of the important attributes of thermally driven Diels-Alder reactions is their concerted mechanism, with consequent high yields and efficiencies relative to liquid photochemical systems. Since the systems we propose involve organic species, with thermal stability concerns about 400/sup 0/C, it is important to demonstrate equilibrium shift capability for the highly energetic reactions sought. We have therefore carried out experimental studies with model liquid Diels-Alder systems that clearly demonstrate the degree of control over equilibrium available through substituent entropy effects. These results are of importance as regards subsequent systematic identification of Diels-Alder reactions having ideal thermochemical and physical properties.

  8. Laser-assisted metal deposition from liquid-phase precursors on polymers

    NASA Astrophysics Data System (ADS)

    Kordás, K.; Békési, J.; Vajtai, R.; Nánai, L.; Leppävuori, S.; Uusimäki, A.; Bali, K.; George, Thomas F.; Galbács, G.; Ignácz, F.; Moilanen, P.

    2001-03-01

    In this work, a short review is presented for results utilizing the technique of laser-assisted metallization of dielectrics. Experimental efforts and results related to the metal (palladium (Pd), copper (Cu) and silver (Ag)) deposition on polymeric materials (polyimide (PI), mylar) are reported. These polymers and metals are chosen due to their growing importance in the rapidly-developing microelectronics packaging industry. The method of laser-induced chemical liquid-phase deposition (LCLD) offers many advantages compared to other techniques such as laser-induced forward transfer (LIFT), pulsed-laser deposition (PLD) and laser-assisted chemical vapor-phase deposition (LCVD). The LCLD is time and cost effective because vacuum tools and special pre-treatments are not required. The consumed chemicals used in precursors are non-harmful and easy to handle due to the liquid phase. For the optimal physical and chemical properties of deposits, the laser and solution parameters are varied. XeCl and KrF excimer and Ar + lasers are employed for executing the palladium, Ag and/or Cu formation on the polymer substrates. Chemical and physical analyses of the formed metal patterns are performed by EDX, XRD, FESEM, SEM, resistance and adhesion measurements.

  9. Liquid-Liquid Phase Separation of a Monoclonal Antibody and Nonmonotonic Influence of Hofmeister Anions

    PubMed Central

    Mason, Bruce D.; Zhang-van Enk, Jian; Zhang, Le; Remmele, Richard L.; Zhang, Jifeng

    2010-01-01

    Liquid-liquid phase separation was studied for a monoclonal antibody in the monovalent salt solutions of KF, KCl, and KSCN under different pH conditions. A modified Carnahan-Starling hard-sphere model was utilized to fit the experimental data, establish the liquid-liquid coexistence curve, and determine antibody-antibody interactions in the form of Tc (critical temperature) under the different solution conditions. The liquid-liquid phase separation revealed the complex relationships between antibody-antibody interactions and different solution conditions, such as pH, ionic strength, and the type of anion. At pH 7.1, close to the pI of the antibody, a decrease of Tc versus ionic strength was observed at low salt conditions, suggesting that the protein-protein interactions became less attractive. At a pH value below the pI of the antibody, a nonmonotonic relationship of Tc versus ionic strength was apparent: initially as the ionic strength increased, protein-protein interactions became more attractive with the effectiveness of the anions following the inverse Hofmeister series; then the interactions became less attractive following the direct Hofmeister series. This nonmonotonic relationship may be explained by combining the charge neutralization by the anions, perhaps with the ion-correlation force for polarizable anions, and their preferential interactions with the antibody. PMID:21112304

  10. Liquid-liquid phase separation of a monoclonal antibody and nonmonotonic influence of Hofmeister anions.

    PubMed

    Mason, Bruce D; Zhang-van Enk, Jian; Zhang, Le; Remmele, Richard L; Zhang, Jifeng

    2010-12-01

    Liquid-liquid phase separation was studied for a monoclonal antibody in the monovalent salt solutions of KF, KCl, and KSCN under different pH conditions. A modified Carnahan-Starling hard-sphere model was utilized to fit the experimental data, establish the liquid-liquid coexistence curve, and determine antibody-antibody interactions in the form of T(c) (critical temperature) under the different solution conditions. The liquid-liquid phase separation revealed the complex relationships between antibody-antibody interactions and different solution conditions, such as pH, ionic strength, and the type of anion. At pH 7.1, close to the pI of the antibody, a decrease of T(c) versus ionic strength was observed at low salt conditions, suggesting that the protein-protein interactions became less attractive. At a pH value below the pI of the antibody, a nonmonotonic relationship of T(c) versus ionic strength was apparent: initially as the ionic strength increased, protein-protein interactions became more attractive with the effectiveness of the anions following the inverse Hofmeister series; then the interactions became less attractive following the direct Hofmeister series. This nonmonotonic relationship may be explained by combining the charge neutralization by the anions, perhaps with the ion-correlation force for polarizable anions, and their preferential interactions with the antibody. PMID:21112304

  11. Liquid-phase study of ozone inactivation of Venezuelan equine encephalomyelitis virus.

    PubMed

    Akey, D H; Walton, T E

    1985-10-01

    Ozone, in a liquid-phase application, was evaluated as a residue-free viral inactivant that may be suitable for use in an arboviral research laboratory. Commonly used sterilizing agents may leave trace residues, be flammable or explosive, and require lengthy periods for gases or residues to dissipate after decontamination of equipment such as biological safety cabinets. Complete liquid-phase inactivation of Venezuelan equine encephalomyelitis virus was attained at 0.025 mg of ozone per liter within 45 min of exposure. The inactivation of 10(6.5) median cell culture infective doses (CCID50 of Venezuelan equine encephalomyelitis virus per milliliter represented a reduction of 99.99997% of the viral particles from the control levels of 10(7.25-7.5) CCID50/ml. A dose-response relationship was demonstrated. Analysis by polynomial regression of the logarithmic values for both ozone concentrations and percent reduction of viral titers had a highly significant r2 of 0.8 (F = 63.6; df = 1, 16). These results, together with those of Akey (J. Econ. Entomol. 75:387-392, 1982) on the use of ozone to kill a winged arboviral vector, indicate that ozone is a promising candidate as a sterilizing agent in some applications for biological safety cabinets and other equipment used in vector studies with arboviruses. PMID:4083884

  12. 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.

  13. 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.

  14. Liquid Phase Sintered Ceramic Bone Scaffolds by Combined Laser and Furnace

    PubMed Central

    Feng, Pei; Deng, Youwen; Duan, Songlin; Gao, Chengde; Shuai, Cijun; Peng, Shuping

    2014-01-01

    Fabrication of mechanically competent bioactive scaffolds is a great challenge in bone tissue engineering. In this paper, ?-tricalcium phosphate (?-TCP) scaffolds were successfully fabricated by selective laser sintering combined with furnace sintering. Bioglass 45S5 was introduced in the process as liquid phase in order to improve the mechanical and biological properties. The results showed that sintering of ?-TCP with the bioglass revealed some features of liquid phase sintering. The optimum amount of 45S5 was 5 wt %. At this point, the scaffolds were densified without defects. The fracture toughness, compressive strength and stiffness were 1.67 MPam1/2, 21.32 MPa and 264.32 MPa, respectively. Bone like apatite layer was formed and the stimulation for apatite formation was increased with increase in 45S5 content after soaking in simulated body fluid, which indicated that 45S5 could improve the bioactivity. Furthermore, MG-63 cells adhered and spread well, and proliferated with increase in the culture time. PMID:25196598

  15. Transient-pressure analysis in geothermal steam reservoirs with an immobile vaporizing liquid phase

    USGS Publications Warehouse

    Moench, A.F.; Atkinson, P.G.

    1978-01-01

    A finite-difference model for the radial horizontal flow of steam through a porous medium is used to evaluate transient-pressure behavior in the presence of an immobile vaporizing or condensing liquid phase. Graphs of pressure drawdown and buildup in terms of dimensionless pressure and time are obtained for a well discharging steam at a constant mass flow rate for a specified time. The assumptions are made that the steam is in local thermal equilibrium with the reservoir rocks, that temperature changes are due only to phase change, and that effects of vapor-pressure lowering are negligible. Computations show that when a vaporizing liquid phase is present the pressure drawdown exhibits behavior similar to that observed in noncondensable gas reservoirs, but delayed in time. A theoretical analysis allows for the computation of this delay and demonstrates that it is independent of flow geometry. The response that occurs upon pressure buildup is markedly different from that in a noncondensable gas system. This result may provide a diagnostic tool for establishing the existence of phase-change phenomena within a reservoir. ?? 1979.

  16. Mid-infrared photoconductive properties of heavily Bi-doped PbTe p-n homojunction diode grown by liquid-phase epitaxy

    NASA Astrophysics Data System (ADS)

    Yasuda, Arata; Suto, Ken; Takahashi, Yatsuhiro; Nishizawa, Jun-ichi

    2014-11-01

    We fabricated a heavily Bi-doped (xBi ? 2 × 1019 cm-3) PbTe p-n homojunction diode that detects mid-infrared wavelengths by the temperature difference method (TDM) under controlled vapor pressure (CVP) liquid phase epitaxy (LPE). The photocurrent density produced by the heavily Bi-doped diode sample is approximately 20 times and 3 times greater than that produced by an undoped and heavily In-doped sample, respectively. By varying the ambient temperature from 15 K to 225 K, the detectable wavelength is tunable from 6.18 ?m to 4.20 ?m. The peak shift of the detectable wavelength is shorter in the heavily Bi-doped sample than in the undoped sample, consistent with our previously proposed model, in which Bi-Bi nearest donor-acceptor pairs are formed in the heavily Bi-doped PbTe liquid phase epitaxial layer. Current-voltage (I-V) measurements of the heavily Bi-doped diode sample under infrared exposure at 77 K indicated a likely leak in the dark current, arising from the deeper levels. From the dark I-V measurements, the activation energy of the deep level was estimated as 0.067 eV, close to the energy of the deep Tl-doped PbTe acceptor layer. We conclude that the deep level originates from the Tl-doped p-type epitaxial layer.

  17. Distribution Coefficient of Copper in Different Soils from Egypt and Greece

    Microsoft Academic Search

    Sabry M. Shaheen; C. D. Tsadilas; T. Mitsibonas; M. Tzouvalekas

    2009-01-01

    Distribution coefficient (Kd) indicates the capability of a soil to retain a solute and consequently its distribution between solid and liquid phase. The purpose of this study was to determine copper (Cu) Kd values of different soils to evaluate their ability to retain it and control its mobility and therefore availability. Eleven surface soil samples varying widely in their origin

  18. Pumice-supported Pd-Pt bimetallic catalysts: Synthesis, structural characterization, and liquid-phase hydrogenation of 1,3-cyclooctadiene

    SciTech Connect

    Deganello, G.; Duca, D.; Liotta, L.F.; Martorana, A.; Venezia, M. [Istituto di Chimica e Technologia dei Prodotti Naturali del CNR, Palermo (Italy)] [Istituto di Chimica e Technologia dei Prodotti Naturali del CNR, Palermo (Italy); Benedetti, A.; Fagherazz, G. [Universita di Venezia, Venice (Italy)] [Universita di Venezia, Venice (Italy)

    1995-01-01

    A series of pumice-supported palladium-platinum bimetallic catalysts were prepared and investigated by X-ray scattering (WAXS and SAXS) and XPS techniques. An alloy Pd-Pt was formed. The less abundant metal was found to segregate to the surface. The catalysts were tested in the liquid-phase hydrogenation of 1,3-cyclooctadiene to cyclooctene, and compared with similarly prepared pumice-supported palladium and platinum catalysts and other supported Pd-Pt catalysts reported in the literature. The addition of platinum reduces the activity and the selectivity of the palladium catalysts. Differences between the activity of these pumice-supported catalysts and the activity of previously described Pd and Pd-Pt catalysts on other supports, are attributed to the presence, in the latter, of diffusional processes. 50 refs., 4 figs. 2 tabs.

  19. Theory of liquid-phase sintering: Model experiments on the tungsten-nickel-copper heavy-alloy system

    SciTech Connect

    Farooq, S.

    1988-01-01

    In most industrially important liquid-phase-sintering systems, like cemented carbides and tungsten heavy alloys, there is considerable deviation from theory. This deviation from classic behavior is related to heating rate, intersolubility of the base in the additive, and initial additive homogeneity. Thus, inclusion of these features into an updated liquid-phase-sintering theory provides better prediction of densification and microstructural coarsening. A computer model of liquid-phase sintering was developed; the factors included in this model are heating rate, particle size, solubility, and additive homogeneity. Coupled with this computer simulation were experimental observations using the tungsten-nickel-copper system. This system provides a spectrum of solubilities representative of common liquid-phase sintering systems. The experiments were designed to illustrate the shortcomings of previous theories of liquid-phase sintering, and to verify the predictions of the theoretical model developed. Results show that the departure from classic theory increases with slow heating rate, high solubility of the base in the additive, and high initial additive homogeneity.

  20. Template-assisted mineral formation via an amorphous liquid phase precursor route

    NASA Astrophysics Data System (ADS)

    Amos, Fairland F.

    The search for alternative routes to synthesize inorganic materials has led to the biomimetic route of producing ceramics. In this method, materials are manufactured at ambient temperatures and in aqueous solutions with soluble additives and insoluble matrix, similar to the biological strategy for the formation of minerals by living organisms. Using this approach, an anionic polypeptide additive was used to induce an amorphous liquid-phase precursor to either calcium carbonate or calcium phosphate. This precursor was then templated on either organic or inorganic substrates. Non-equilibrium morphologies, such as two-dimensional calcium carbonate films, one-dimensional calcium carbonate mesostructures and "molten" calcium phosphate spherulites were produced, which are not typical of the traditional (additive-free) solution grown crystals in the laboratory. In the study of calcium carbonate, the amorphous calcium carbonate mineral formed via the liquid-phase precursor, either underwent a dissolution-recrystallization event or a pseudo-solid-state transformation to produce different morphologies and polymorphs of the mineral. Discrete or aggregate calcite crystals were formed via the dissolution of the amorphous phase to allow the reprecipitation of the stable crystal. Non-equilibrium morphologies, e.g., films, mesotubules and mesowires were templated using organic and inorganic substrates and compartments. These structures were generated via an amorphous solid to crystalline solid transformation. Single crystalline tablets and mesowires of aragonite, which are reported to be found only in nature as skeletal structures of marine organisms, such as mollusk nacre and echinoderm teeth, were successfully synthesized. These biomimetic structures were grown via the polymer-induced liquid-phase precursor route in the presence of magnesium. Only low magnesium-bearing calcite was formed in the absence of the polymer. A similar approach of using a polymeric additive was implemented in calcium phosphate. Spherulitic crystals and films, seemingly formed from a molten state, were produced. These structures served as nucleating surfaces for the radial formation of calcium oxalate minerals. The composite calcium phosphate-calcium oxalate assemblies are similar to the core-shell structures found in certain kidney stones.

  1. Accurate measurements of infinite dilution activity coefficients using gas chromatography with static-wall-coated open-tubular columns.

    PubMed

    Xu, Qianqian; Su, Baogen; Luo, Xinyi; Xing, Huabin; Bao, Zongbi; Yang, Qiwei; Yang, Yiwen; Ren, Qilong

    2012-11-01

    Wall-coated open-tubular (WCOT) columns provide higher column efficiency and lower solute interfacial adsorption effect than packed columns. However, previous efforts used to measure the infinite dilution activity coefficient (?(?)) via a chromatographic technique have used packed columns, because the low carrier gas flow rate (U) and the small stationary phase amount (n(2)) in WCOT columns raise large errors. By rationally revising the ?(?)-calculation equation for static-wall-coated open-tubular column, we observed that U and n(2) are not necessarily needed and the resulting error could be reduced, and WCOT column gas chromatography subsequently became a superior method for the accurate ?(?) determination. In this study, we validate our revised ?(?)-calculation equation by measuring ?(?) in an ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate system, in which 55 organic compounds covering a wide range of functional groups were used as probe solutes and their ?(?) values in the ionic liquid were determined at 40.0, 50.0, and 60.0 °C. Experimental error analysis shows that our revised equation remarkably reduces the error compared to the common ?(?)-calculation equation. Our data is consistent with previously reported values obtained via other techniques, which further proves the credibility of our revised equation. The accurately determined ?(?) values can be directly used to calculate the partial molar excess enthalpy, selectivity, and capacity, which will benefit for the rapid screening of solvents (especially ionic liquids) in separation approaches. PMID:23039405

  2. EFFECTS OF COVAPORS ON ADSORPTION RATE COEFFICIENTS OF ORGANIC VAPORS ADSORBED ONTO ACTIVATED CARBON FROM FLOWING AIR

    SciTech Connect

    G. WOOD

    2000-12-01

    Published breakthrough time, adsorption rate, and capacity data for components of organic vapor mixtures adsorbed from flows through fixed activated carbon beds have been analyzed. Capacities (as stoichiometric centers of constant pattern breakthrough curves) yielded stoichiometric times {tau}, which are useful for determining elution orders of mixture components. We also calculated adsorption rate coefficients k{sub v} of the Wheeler (or, more general Reaction Kinetic) breakthrough curve equation, when not reported, from breakthrough times and {tau}. Ninety-five k{sub v} (in mixture)/ k{sub v} (single vapor) ratios at similar vapor concentrations were calculated and averaged for elution order categories. For 43 first-eluting vapors the average ratio (1.07) was statistically no different (0.21 standard deviation) than unity, so that we recommend using the single-vapor k{sub v} for such. Forty-seven second-eluting vapor ratios averaged 0.85 (0.24 standard deviation), also not significantly different from unity; however, other evidence and considerations lead us recommend using k{sub v} (in mixture) = 0.85 k{sub v} (single vapor). Five third- and fourth-eluting vapors gave an average of 0.56 (0.16 standard deviation) for a recommended k{sub v} (in mixture) = 0.56 k{sub v} (single vapor) for such.

  3. Linear solvation energy relationship of the limiting partition coefficient of organic solutes between water and activated carbon

    USGS Publications Warehouse

    Luehrs, Dean C.; Hickey, James P.; Nilsen, Peter E.; Godbole, K.A.; Rogers, Tony N.

    1995-01-01

    A linear solvation energy relationship has been found for 353 values of the limiting adsorption coefficients of diverse chemicals:? log K = ?0.37 + 0.0341Vi ? 1.07? + D + 0.65P with R = 0.951, s = 0.51, n = 353, and F = 818.0, where Vi is the intrinsic molar volume; ? is a measure of the hydrogen bond acceptor strength of the solute; D is an index parameter for the research group which includes the effects of the different types of carbon used, the temperature, and the length of time allowed for the adsorption equilibrium to be established; and P is an index parameter for the flatness of the molecule. P is defined to be unity if there is an aromatic system in the molecule or if there is a double bond or series of conjugated double bonds with no more that one non-hydrogen atom beyond the double bond and zero otherwise. A slightly better fit is obtained if the two-thirds power of Vi is used as a measure of the surface area in place of the volume term:? log K = ?1.75 + 0.227V2/3 ? 1.10? + D + 0.60P with R = 0.954, s = 0.49, n = 353, and F = 895.39. This is the first quantitative measure of the effect of the shape of the molecule on its tendency to be adsorbed on activated carbon.

  4. Quantitative Apparent Diffusion Coefficient Measurements Obtained by 3-Tesla MRI Are Correlated with Biomarkers of Bladder Cancer Proliferative Activity

    PubMed Central

    Sevcenco, Sabina; Haitel, Andrea; Ponhold, Lothar; Susani, Martin; Fajkovic, Harun; Shariat, Shahrokh F.; Hiess, Manuela; Spick, Claudio; Szarvas, Tibor; Baltzer, Pascal A. T.

    2014-01-01

    Purpose To investigate the association between Apparent Diffusion Coefficient (ADC) values and cell cycle and proliferative biomarkers (p53, p21, Ki67,) in order to establish its potential role as a noninvasive biomarker for prediction of cell cycle, proliferative activity and biological aggressiveness in bladder cancer. Materials and Methods Patients with bladder cancer who underwent 3,0 Tesla DW-MRI of the bladder before TUR-B or radical cystectomy were eligible for this prospective IRB-approved study. Histological specimen were immunohistochemically stained for the following markers: p53, p21 and ki67. Two board-certified uropathologists reviewed the specimens blinded to DW-MRI results. Histological grade and T-stage were classified according to the WHO 2004 and the 2009 TNM classification, respectively. Nonparametric univariate and multivariate statistics including correlation, logistic regression and ROC analysis were applied. Results Muscle invasive bladder cancer was histologically confirmed in 10 out of 41 patients. All examined tissue biomarkers were significantly correlated with ADC values (p<0.05, respectively). Based on multivariate analysis, p53 and ADC are both independent prognostic factors for muscle invasiveness of bladder cancer (>/?=?T2). (p?=?0.013 and p?=?0.018). Conclusion ADC values are associated with cell cycle and proliferative biomarkers and do thereby reflect invasive and proliferative potential in bladder cancer. ADC and p53 are both independent prognostic factors for muscle invasiveness in bladder cancer. PMID:25202965

  5. Limiting activity coefficients of aqueous flavour systems at 298 K by the group contribution solvation (GCS) model

    NASA Astrophysics Data System (ADS)

    Nanu, Diana E.; de Loos, Theodoor W.

    In this work a new approach for using the GCS model is applied to predict the infinite dilution activity coefficients, ??, for aroma compounds in water. It involves the use of a better expression for the combinatorial contribution to ??, and a different treatment of the values of the ?-scaling factors used in the cavity size definition in the quantum chemical solvation calculations. The ? values for each functional group in the solvation calculations in water are optimized based on few experimental data of ??. The present approach is applied for describing aqueous systems of n-alkanols and methyl-ketones. The results discussed here show that the predicted ?? values are within the experimental accuracy for most of the compounds, and are more accurate than predictions using the classical UNIFAC-type group contribution models. Furthermore, a simple group contribution approach was developed based on quantum-computed quantities, which makes it possible to extend the applicability of the model without expensive quantum calculations. It is shown that such an approach is able to describe ?? well, even for larger systems.

  6. Spectroscopic-ellipsometric study of native oxide removal by liquid phase HF process.

    PubMed

    Kurhekar, Anil Sudhakar; Apte, Prakash R

    2013-02-22

    Ex situ spectroscopic ellipsometry (SE) measurements have been employed to investigate the effect of liquid-phase hydrofluoric acid (HF) cleaning on Si<100> surfaces for microelectromechanical systems application. The hydrogen terminated (H-terminated) Si surface was realized as an equivalent dielectric layer, and SE measurements are performed. The SE analyses indicate that after a 20-s 100:5 HF dip with rinse, the Si (100) surface was passivated by the hydrogen termination and remained chemically stable. Roughness of the HF-etched bare Si (100) surface was observed and analyzed by the ex-situ SE. Evidence for desorption of the H-terminated Si surface layer is studied using Fourier transform infrared spectroscopy and ellipsometry, and discussed. This piece of work explains the usage of an ex situ, non-destructive technique capable of showing state of passivation, the H-termination of Si<100> surfaces. PMID:24619506

  7. Liquid-phase thermodynamics and structures in the Cu-Nb binary system

    NASA Astrophysics Data System (ADS)

    Zhang, Liang; Martinez, Enrique; Caro, Alfredo; Liu, Xiang-Yang; Demkowicz, Michael J.

    2013-03-01

    An embedded atom method (EAM) interatomic potential is constructed to reproduce the main topological features of the experimental equilibrium phase diagram of the Cu-Nb system in both solid and liquid states. The potential is fitted to composition-dependent enthalpies of mixing for bcc and fcc random solid solutions obtained from first-principles calculations at 0 K. Compared with two other EAM Cu-Nb potentials in the literature, the phase diagram of the current potential shows better agreement with the experimental phase diagram. Our potential predicts that the Cu-Nb liquid phase at equilibrium is compositionally patterned over lengths of about 2.3 nm. The newly constructed potential may be used to study the effect of liquid thermodynamics and structure on properties of binary systems, such as radiation-induced mixing.

  8. Possible chiral spin-liquid phase in noncentrosymmetric RBaCo4O7

    NASA Astrophysics Data System (ADS)

    Khalyavin, D. D.; Manuel, P.; Chapon, L. C.

    2012-06-01

    Based on a symmetry approach, we propose a possible explanation of the weak ferromagnetic component recently observed in YBaCo3FeO7 [M. Valldor , Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.84.224426 84, 224426 (2011)] and other isostructural compounds in the high-temperature spin-liquid phase. Due to the polar nature of their crystal structure, a coupling between time-odd scalar spin chirality which we suggest as the primary order parameter and macroscopic magnetization is possible as follows from the general form of the appropriate free-energy invariant. The deduced pseudoproper coupling between both physical quantities provides a unique possibility to study the critical behavior of the chiral order parameter.

  9. Harnessing the liquid-phase exfoliation of graphene using aliphatic compounds: a supramolecular approach.

    PubMed

    Ciesielski, Artur; Haar, Sébastien; El Gemayel, Mirella; Yang, Huafeng; Clough, Joseph; Melinte, Georgian; Gobbi, Marco; Orgiu, Emanuele; Nardi, Marco V; Ligorio, Giovanni; Palermo, Vincenzo; Koch, Norbert; Ersen, Ovidiu; Casiraghi, Cinzia; Samorì, Paolo

    2014-09-22

    The technological exploitation of the extraordinary properties of graphene relies on the ability to achieve full control over the production of a high-quality material and its processing by up-scalable approaches in order to fabricate large-area films with single-layer or a few atomic-layer thickness, which might be integrated in working devices. A simple method is reported for producing homogenous dispersions of unfunctionalized and non-oxidized graphene nanosheets in N-methyl-2-pyrrolidone (NMP) by using simple molecular modules, which act as dispersion-stabilizing compounds during the liquid-phase exfoliation (LPE) process, leading to an increase in the concentration of graphene in dispersions. The LPE-processed graphene dispersion was shown to be a conductive ink. This approach opens up new avenues for the technological applications of this graphene ink as low-cost electrodes and conducting nanocomposite for electronics. PMID:25044532

  10. Liquid-phase exfoliation of expanded graphites into graphene nanoplatelets using amphiphilic organic molecules.

    PubMed

    Park, Ji Sun; Yu, Lan; Lee, Churl Seung; Shin, Kwonwoo; Han, Jong Hun

    2014-03-01

    Graphenes with a two-dimensional lattice of carbons have been widely employed in diverse applications owing to their excellent electrical, thermal, mechanical, and gas-barrier properties. However, the frequently-used reduced graphene oxide (rGO), which is synthesized from natural graphites by strong oxidation and subsequent reduction via highly toxic components, exhibits imperfect characteristics because of remaining defect sites on its basal planes. Therefore, in this work, we present a convenient way to prepare graphene nanoplatelets (GNPs) with minimized defect sites on their basal planes employing liquid-phase exfoliation of edge-functionalized expanded graphites (EGs) with amphiphilic organic molecules. Exfoliated GNPs revealed approximately sub-7-nm-thickness and showed stable dispersibility in an organic media during 9 months. Furthermore, spray-coated GNP films presented homogeneously stacked morphologies without noticeable agglomerations. PMID:24407700

  11. Soft liquid phase adsorption for fabrication of organic semiconductor films on wettability patterned surfaces.

    PubMed

    Watanabe, Satoshi; Akiyoshi, Yuri; Matsumoto, Mutsuyoshi

    2014-01-01

    We report a soft liquid-phase adsorption (SLPA) technique for the fabrication of organic semiconductor films on wettability-patterned substrates using toluene/water emulsions. Wettability-patterned substrates were obtained by the UV-ozone treatment of self-assembled monolayers of silane coupling agents on glass plates using a metal mask. Organic semiconductor polymer films were formed selectively on the hydrophobic part of the wettability-patterned substrates. The thickness of the films fabricated by the SLPA technique is significantly larger than that of the films fabricated by dip-coating and spin-coating techniques. The film thickness can be controlled by adjusting the volume ratio of toluene to water, immersion angle, immersion temperature, and immersion time. The SLPA technique allows for the direct production of organic semiconductor films on wettability-patterned substrates with minimized material consumption and reduced number of fabrication steps. PMID:25296571

  12. Surface Specularity as an Indicator of Shock-induced Solid-liquid Phase Transitions in Tin

    SciTech Connect

    G. D. Stevens, S. S. Lutz, B. R. Marshall, W.D. Turley, et al.

    2007-12-01

    When highly polished metal surfaces melt upon release after shock loading, they exhibit features that suggest significant surface changes accompany the phase transition. The reflection of light from such surfaces changes from specular (pre-shock) to diffuse upon melting. Typical of this phenomenon is the loss of signal light in velocity interferometer system for any reflector (VISAR) measurements, which usually occurs at pressures high enough to melt the free surface. Unlike many other potential material phase-sensitive diagnostics (e.g., reflectometry, conductivity), that show relatively small (1%-10%) changes, the specularity of reflection provides a more sensitive and definitive (>10x) indication of the solid-liquid phase transition. Data will be presented that support the hypothesis that specularity changes indicate melt in a way that can be measured easily and unambiguously.

  13. Solid-liquid phase coexistence of alkali nitrates from molecular dynamics simulations.

    SciTech Connect

    Jayaraman, Saivenkataraman

    2010-03-01

    Alkali nitrate eutectic mixtures are finding application as industrial heat transfer fluids in concentrated solar power generation systems. An important property for such applications is the melting point, or phase coexistence temperature. We have computed melting points for lithium, sodium and potassium nitrate from molecular dynamics simulations using a recently developed method, which uses thermodynamic integration to compute the free energy difference between the solid and liquid phases. The computed melting point for NaNO3 was within 15K of its experimental value, while for LiNO3 and KNO3, the computed melting points were within 100K of the experimental values [4]. We are currently extending the approach to calculate melting temperatures for binary mixtures of lithium and sodium nitrate.

  14. Growth and characterization of liquid phase epitaxially grown spinel ferrite films

    NASA Astrophysics Data System (ADS)

    Vanderstraten, P. J. M.

    1980-11-01

    The characteristics of ferrimagnetic and ferromagnetic materials are reviewed with particular emphasis on the uniaxial magnetic anisotropy which may be presented in liquid phase epitaxy (LPE) grown in spinel ferrite films. The properties of spinel ferrites are explored and the preparation of substrates for the growth of ferrite films are considered. The LPE growth procedure as well as methods for characterizing film thickness and film lattice parameters, composition, and saturation magnetization are described as well as magnetic anisotropies, the magnetic domain configuration and uniaxial anisotropy. The growth of indium substituted magnesium ferrite films, LPE growth of lithium-ferrite-alluminate films, LPE growth of copper ferrite films, stress induced anisotropy in LPE grown Ni(Fe, Al)204 films, and the LPE growth of Mn, Ni, and Al-substituted copper ferrite films are discussed.

  15. Methods for sulfate removal in liquid-phase catalytic hydrothermal gasification of biomass

    DOEpatents

    Elliott, Douglas C; Oyler, James

    2013-12-17

    Processing of wet biomass feedstock by liquid-phase catalytic hydrothermal gasification must address catalyst fouling and poisoning. One solution can involve heating the wet biomass with a heating unit to a pre-treatment temperature sufficient for organic constituents in the feedstock to decompose, for precipitates of inorganic wastes to form, for preheating the wet feedstock in preparation for subsequent removal of soluble sulfate contaminants, or combinations thereof. Processing further includes reacting the soluble sulfate contaminants with cations present in the feedstock material to yield a sulfate-containing precipitate and separating the inorganic precipitates and/or the sulfate-containing precipitates out of the wet feedstock. Having removed much of the inorganic wastes and the sulfate contaminants that can cause poisoning and fouling, the wet biomass feedstock can be exposed to the heterogenous catalyst for gasification.

  16. Micromechanics of deformation in porous liquid phase sintered alumina under hertzian contact

    SciTech Connect

    DIGIOVANNI,ANTHONY A.; CHAN,HELEN M.; HARMER,MARTIN P.; NIED,HERMAN F.

    2000-05-15

    A series of fine-grained porous alumina samples, with and without a liquid phase, were fabricated in compositions matched closely to commercially available alumina used as a microelectronic substrates. Hertzian indentation on monolithic specimens of the glass-containing samples produced a greater quasi-ductile stress-strain response compared to that observed in the pure alumina. Maximum residual indentation depths, determined from surface profilometry, correlated with the stress-strain results. Moreover, microstructural observations from bonded interface specimens revealed significantly more damage in the form of microcracking and under extreme loading, pore collapse, in the glass-containing specimens. The absence of the typical twin faulting mechanism observed for larger-grained alumina suggests that the damage mechanism for quasi-ductility in these fine-grained porous alumina derived from the pores acting as a stress concentrator and the grain boundary glass phase providing a weak path for short crack propagation.

  17. Spectroscopic-ellipsometric study of native oxide removal by liquid phase HF process

    PubMed Central

    Kurhekar, Anil Sudhakar; Apte, Prakash R

    2014-01-01

    Ex situ spectroscopic ellipsometry (SE) measurements have been employed to investigate the effect of liquid-phase hydrofluoric acid (HF) cleaning on Si<100> surfaces for microelectromechanical systems application. The hydrogen terminated (H-terminated) Si surface was realized as an equivalent dielectric layer, and SE measurements are performed. The SE analyses indicate that after a 20-s 100:5 HF dip with rinse, the Si (100) surface was passivated by the hydrogen termination and remained chemically stable. Roughness of the HF-etched bare Si (100) surface was observed and analyzed by the ex-situ SE. Evidence for desorption of the H-terminated Si surface layer is studied using Fourier transform infrared spectroscopy and ellipsometry, and discussed. This piece of work explains the usage of an ex situ, non-destructive technique capable of showing state of passivation, the H-termination of Si<100> surfaces. PMID:24619506

  18. Liquid phase oxidation for InGaP/GaAs HBT passivation

    NASA Astrophysics Data System (ADS)

    Sze, Po-Wen; Lee, Kuan-Wei; Huang, Jian-Jiun; Yang, Nan-Ying; Wang, Yeong-Her

    2006-08-01

    Native oxide films grown near room temperature by liquid phase oxidation (LPO) on p+-GaAs, n-InGaAs and n-InGaP are investigated. Their applications to heterojunction bipolar transistors (HBTs) are also demonstrated and characterized. With the LPO as surface passivation, the dc current gain ? of the HBT devices increases sevenfold in low collector current regimes, and it also shows wider collector regimes from 8.3 × 10-11 A to 0.1 A. In addition, a larger breakdown voltage and lower surface recombination current can be obtained. This provides the possibility of promising implementations in low-power electronics and communication applications. Comparisons between devices with LPO passivation and those with sulfur treatment on the InGaP/GaAs HBTs are also discussed.

  19. Liquid Phase - Pulsed Laser Ablation: A route to fabricate different carbon nanostructures

    NASA Astrophysics Data System (ADS)

    Al-Hamaoy, Ahmed; Chikarakara, Evans; Jawad, Hussein; Gupta, Kapil; Kumar, Dinesh; Rao, M. S. Ramachandra; Krishnamurthy, Satheesh; Morshed, Muhammad; Fox, Eoin; Brougham, Dermot; He, Xiaoyun; Vázquez, Mercedes; Brabazon, Dermot

    2014-05-01

    Carbon nanostructures in various forms and sizes, and with different speciation properties have been prepared from graphite by Liquid Phase - Pulsed Laser Ablation (LP-PLA) using a high frequency Nd:YAG laser. High energy densities and pulse repetition frequencies of up to 10 kHz were used in this ablation process to produce carbon nanomaterials with unique chemical structures. Dynamic Light Scattering (DLS), micro-Raman and High-Resolution Transmission Electron Microscopy (HRTEM) were used to confirm the size distribution, morphology, chemical bonding, and crystallinity of these nanostructures. This article demonstrates how the fabrication process affects measured characteristics of the produced carbon nanomaterials. The obtained particle properties have potential use for various applications including biochemical speciation applications.

  20. Construction materials for reaction unit in the liquid-phase synthesis of propylene oxide

    SciTech Connect

    Zaritskii, V.I.D.

    1987-09-01

    The main components of the reaction medium in equipment for the synthesis of propylene oxide by liquid-phase oxidation of gaseous propylene with peracetic acid are propylene, peracetic acid, ethyl acetate, acetic acid, propylene oxide, carbon dioxide, oxygen, methane, and propylene glycol acetates. The operating conditions of the equipment and content of the main components of the medium are shown. Results are given for the investigation of the corrosion behavior of 12Kh18N10T, 10Kh17N13M2T, 08Kh22N6T, and 08Kh21N6M2T steels, AD0 and AD1 aluminum, and VT1-0 titanium. VSt3 carbon steel was tested for comparison.

  1. Diffusion Coefficients and Viscosities of CO2 + H2O, CO2 + CH3OH, NH3 + H2O, and NH3 + CH3OH Liquid Mixtures

    Microsoft Academic Search

    Marco J. W. Frank; Johannes A. M. Kuipers; Swaaij van W. P. M

    1996-01-01

    To evaluate quantitatively the results of gas-liquid absorption experiments, accurate liquid-phase diffusion coefficients and viscosities are needed. In this paper experimental values of these quantities will be reported for the binary systems carbon dioxide + water, carbon dioxide + methanol, ammonia + water, and ammonia + methanol. The diffusion coefficients have been measured using the Taylor-Aris dispersion method, and the

  2. Diffusion coefficients and viscosities of COâ + HâO, COâ + CHâOH, NHâ + HâO, and NHâ + CHâOH liquid mixtures

    Microsoft Academic Search

    M. J. W. Frank; J. A. M. Kuipers; W. P. M. van Swaaij

    1996-01-01

    To evaluate quantitatively the results of gas-liquid absorption experiments, accurate liquid-phase diffusion coefficients and viscosities are needed. In this paper experimental values of these quantities will be reported for the binary systems carbon dioxide + water, carbon dioxide + methanol, ammonia + water, and ammonia + methanol. The diffusion coefficients have been measured using the Taylor-Aris dispersion method, and the

  3. Catalytic activity of Cu\\/MgO in liquid phase oxidation of cumene

    Microsoft Academic Search

    Shuai Xu; Chongpin Huang; Jie Zhang; Biaohua Chen

    2009-01-01

    Cumene was oxidized with air as the oxidant and Cu\\/MgO as the catalyst. Cu\\/MgO with different compositions was prepared by\\u000a co-precipitation and then characterized by X-ray diffraction (XRD), H2-temperature programmed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS). The characterization results showed that CuO dispersed on MgO well in the\\u000a cases that the Cu content in Cu\\/MgO was 1% by molar.

  4. Kalman filter for updating the coefficients of regression models. A case study from an activated sludge waste-water treatment plant

    Microsoft Academic Search

    Pekka Teppola; Satu-Pia Mujunen; Pentti Minkkinen

    1999-01-01

    A Kalman filter was developed to overcome the problems caused by process drifting. Different types of models were used to predict response variables of an activated sludge waste-water treatment plant. These models were constructed using MLR, PCR, and PLS. The MLR-type regression coefficients were calculated for both the PCR and PLS models. After that, the Kalman filter was used to

  5. Molecular Simulation of Henry's Constant at Vapor-Liquid and Liquid-Liquid Phase Richard J. Sadus

    E-print Network

    Molecular Simulation of Henry's Constant at Vapor-Liquid and Liquid-Liquid Phase Boundaries Richard to determine Henry's constant from the residual chemical potential at infinite dilution at the vapor-liquid coexistence. 1. Introduction Henry's constant is a well-known measure of a solute's solubility in a particular

  6. Leveraging the ambipolar transport in polymeric field-effect transistors via blending with liquid-phase exfoliated graphene.

    PubMed

    El Gemayel, Mirella; Haar, Sébastien; Liscio, Fabiola; Schlierf, Andrea; Melinte, Georgian; Milita, Silvia; Ersen, Ovidiu; Ciesielski, Artur; Palermo, Vincenzo; Samorì, Paolo

    2014-07-23

    Enhancement in the ambipolar behavior of field-effect transistors based on an n-type polymer, P(NDI2OD-T2), is obtained by co-deposition with liquid-phase exfoliated graphene. This approach provides a prospective pathway for the application of graphene-based nanocomposites for logic circuits. PMID:24862253

  7. Liquid phase-enabled reaction of AleGa and AleGaeIneSn alloys with water

    E-print Network

    Woodall, Jerry M.

    Liquid phase-enabled reaction of AleGa and AleGaeIneSn alloys with water Jeffrey T. Ziebarth aGaeIneSn alloys is investigated as a means to utilize the chemical potential energy of Al to split water for the production of H2. Al in bulk quantities of these alloys participates in a heterogeneous reaction with water

  8. Influence of ultrasound power on the alkylation of phenylacetonitrile under solid-liquid phase transfer catalysis conditions

    Microsoft Academic Search

    Richard Guilet; Jacques Berlan; Olivier Louisnard; Jacques Schwartzentruber

    1998-01-01

    The influence of ultrasound power on the C-alkylation of phenylacetonitrile by ethyl bromide was studied under solid-liquid phase transfer catalysis in the presence of potassium hydroxide and tetrabutylammonium hydrogenosulfate. Experimental results are reported on the influence of the ultrasonic power on the yields. The optimum efficiency of ultrasound is determined and the way in which ultrasound power may affect the

  9. Effect of liquid phase composition on the microstructure and properties of (W,Ti)C cemented carbide cutting tools

    E-print Network

    Hong, Soon Hyung

    Effect of liquid phase composition on the microstructure and properties of (W,Ti)C cemented carbide: Received 15 July 2007 Accepted 4 April 2008 Keywords: (W,Ti)C Cemented carbides Microstructure Hardness Magnetic properties a b s t r a c t The microstructure and properties of (W,Ti)C cemented carbides

  10. Transient liquid phase bonding of Inconel 718 and Inconel 625 with BNi-2: Modeling and experimental investigations

    Microsoft Academic Search

    M. A. Arafin; M. Medraj; D. P. Turner; P. Bocher

    2007-01-01

    In this study, a combination of direct experimentation and computational modeling approach was used to predict the time required to complete isothermal solidification during the transient liquid phase bonding of Inconel 718 and 625 superalloys, two most commonly used superalloys in aero-engine hot section components, with nickel based filler alloy, BNi-2. However, unlike conventional modeling, the diffusion of solute atoms

  11. Transient Liquid Phase Diffusion Bonding of Magnesium Alloy (Mg-AZ31) to Titanium Alloy (Ti-6Al-4V)

    NASA Astrophysics Data System (ADS)

    Atieh, Anas Mahmoud

    The magnesium alloy Mg-AZ31 and titanium alloy Ti-6Al-4V have physical characteristics and mechanical properties that makes it attractive for a wide range of engineering applications in the aerospace and automotive industries. However, the differences in melting temperature and coefficient of thermal expansion hinder the use of traditional fusion welding techniques. Transient liquid phase (TLP) bonding of magnesium alloy Mg-AZ31 and titanium alloy Ti-6Al- 4V was performed and different interlayer types and configurations were used to facilitate joint formation. The joining of these alloys using Ni foils was successful at a bonding temperature of 515°C, bonding pressure 0.2 MPa, for bonding time of 5 minutes. At the Ni/Mg-AZ31 bond interface, the formation of a eutectic liquid between Mg and Ni was observed. The formation of Mg2Ni and Mg3AlNi2 were identified along the bond interface resulting in an isothermally solidified joint. At the Ni/Ti-6Al-4V interface, the solid-state diffusion process results in joint formation. The use of double Ni-Cu sandwich joint resulted in further enhancement in joint formation and this produced joints with greater shear strength values. The configuration of Mg-AZ31/Cu- Ni/Ti-6Al-4V or Mg-AZ31/Ni-Cu/Ti-6Al-4V influence the mechanism of bonding and the type of intermetallics formed within the joint. The application of thin Ni electrodeposited coatings resulted in further enhancements of joint quality due to better surface-to-surface contact and a reduction in the formation of intermetallics at the joint. The effect of Cu nano-particles in the coatings was found to decrease the eutectic zone width and this resulted in an increase the shear strength of the joints. The highest shear strength of 69 MPa was possible with bonds made using coatings containing Cu nano-particle dispersion.

  12. Unraveling the behavior of the individual ionic activity coefficients on the basis of the balance of ion-ion and ion-water interactions

    E-print Network

    Mónika Valiskó; Dezs? Boda

    2014-09-15

    We investigate the individual activity coefficients of pure 1:1 and 2:1 electrolytes using our theory that is based on the competition of ion-ion (II) and ion-water (IW) interactions (Vincze et al., J. Chem. Phys. 133, 154507, 2010). The II term is computed from Grand Canonical Monte Carlo simulations on the basis of the implicit solvent model of electrolytes using hard sphere ions with Pauling radii. The IW term is computed on the basis of Born's treatment of solvation using experimental hydration free energies. The two terms are coupled through the concentration-dependent dielectric constant of the electrolyte. With this approach we are able to reproduce the nonmonotonic concentration dependence of the mean activity coefficient of pure electrolytes qualitatively without using adjustable parameters. In this paper, we show that the theory can provide valuable insight into the behavior of individual activity coefficients too. We compare our theoretical predictions against experimental data measured by electrochemical cells containing ion-specific electrodes. As in the case of the mean activity coefficients, we find good agreement for 2:1 electrolytes, while the accuracy of our model is worse for 1:1 systems. This deviation in accuracy is explained by the fact that the two competing terms (II and IW) are much larger in the 2:1 case so errors in the two separate terms have less effects. The difference of the excess chemical potentials of cations and anions (the ratio of activity coefficients) is determined by asymmetries in the properties of the two ions: charge, radius, and hydration free energies.

  13. SOLID-LIQUID PHASE TRANSFER CATALYZED SYNTHESIS OF CINNAMYL ACETATE-KINETICS AND ANALYSIS OF FACTORS AFFECTING THE REACTION IN A BATCH REACTOR

    EPA Science Inventory

    The use of solid-liquid phase transfer catalysis has an advantage of carrying out reaction between two immiscible substrates, one in solid phase and the other in liquid phase, with high selectivity and at relatively low temperatures. In this study we investigated the synthesis ci...

  14. In Situ Activation of Microcapsules

    NASA Technical Reports Server (NTRS)

    Morrison, Dennis R. (Inventor); Mosier, Benjamin (Inventor)

    2000-01-01

    Disclosed are microcapsules comprising a polymer shell enclosing two or more immiscible liquid phases in which a drug, or a prodrug and a drug activator are partitioned into separate phases. or prevented from diffusing out of the microcapsule by a liquid phase in which the drug is poorly soluble. Also disclosed are methods of using the microcapsules for in situ activation of drugs where upon exposure to an appropriate energy source the internal phases mix and the drug is activated in situ.

  15. Gas-particle partitioning of semi-volatile organics on organic aerosols using a predictive activity coefficient model: analysis of the effects of parameter choices on model performance

    NASA Astrophysics Data System (ADS)

    Chandramouli, Bharadwaj; Jang, Myoseon; Kamens, Richard M.

    The partitioning of a diverse set of semivolatile organic compounds (SOCs) on a variety of organic aerosols was studied using smog chamber experimental data. Existing data on the partitioning of SOCs on aerosols from wood combustion, diesel combustion, and the ?-pinene-O 3 reaction was augmented by carrying out smog chamber partitioning experiments on aerosols from meat cooking, and catalyzed and uncatalyzed gasoline engine exhaust. Model compositions for aerosols from meat cooking and gasoline combustion emissions were used to calculate activity coefficients for the SOCs in the organic aerosols and the Pankow absorptive gas/particle partitioning model was used to calculate the partitioning coefficient Kp and quantitate the predictive improvements of using the activity coefficient. The slope of the log K p vs. log p L0 correlation for partitioning on aerosols from meat cooking improved from -0.81 to -0.94 after incorporation of activity coefficients i? om. A stepwise regression analysis of the partitioning model revealed that for the data set used in this study, partitioning predictions on ?-pinene-O 3 secondary aerosol and wood combustion aerosol showed statistically significant improvement after incorporation of i? om, which can be attributed to their overall polarity. The partitioning model was sensitive to changes in aerosol composition when updated compositions for ?-pinene-O 3 aerosol and wood combustion aerosol were used. The octanol-air partitioning coefficient's ( KOA) effectiveness as a partitioning correlator over a variety of aerosol types was evaluated. The slope of the log K p- log K OA correlation was not constant over the aerosol types and SOCs used in the study and the use of KOA for partitioning correlations can potentially lead to significant deviations, especially for polar aerosols.

  16. Storing solar energy with liquid phase Diels-Alder reactions. Final report

    SciTech Connect

    Poling, B.E.

    1983-07-28

    At the beginning of this project, a preliminary study was completed that indicated the Diels-Alder reaction between maleic anhydride and 2 methyl furan had an energy storage capacity greater than water. During the last two years when this grant was in effect, three additional projects have been completed. First, an improved calorimetric techniques was developed for determination of the energy storage capacity of a reversible liquid phase chemical reaction. This technique confirmed the validity of the earlier results for the maleic anhydride-methyl furan reaction. Second, a technique was developed for characterizing solution nonidealities for mixtures in which reversible chemical reactions occur. It was found that for the maleic anhydride-2 methyl furan reaction, these non idealities could affect equilibrium compositions by nearly 40%. Third, drop calorimetry was used as a screening method to examine sixteen reactions for their potential as energy storage candidates. Of the sixteen examined, three (all involving maleic anhydride and substituted furan) showed an increased energy storage capacity due to reaction while the remaining thirteen showed no increase. In the following report, results of these three studies are summarized. Finally, a general summary of the status of energy storage by chemical reactions is presented.

  17. Preparation and Optical Properties of Spherical Inverse Opals by Liquid Phase Deposition Using Spherical Colloidal Crystals

    NASA Astrophysics Data System (ADS)

    Aoi, Y.; Tominaga, T.

    2013-03-01

    Titanium dioxide (TiO2) inverse opals in spherical shape were prepared by liquid phase deposition (LPD) using spherical colloidal crystals as templates. Spherical colloidal crystals were produced by ink-jet drying technique. Aqueous emulsion droplets that contain polystyrene latex particles were ejected into air and dried. Closely packed colloidal crystals with spherical shape were obtained. The obtained spherical colloidal crystals were used as templates for the LPD. The templates were dispersed in the deposition solution of the LPD, i.e. a mixed solution of ammonium hexafluorotitanate and boric acid and reacted for 4 h at 30 °C. After the LPD process, the interstitial spaces of the spherical colloidal crystals were completely filled with titanium oxide. Subsequent heat treatment resulted in removal of templates and spherical titanium dioxide inverse opals. The spherical shape of the template was retained. SEM observations indicated that the periodic ordered voids were surrounded by titanium dioxide. The optical reflectance spectra indicated that the optical properties of the spherical titanium dioxide inverse opals were due to Bragg diffractions from the ordered structure. Filling in the voids of the inverse opals with different solvents caused remarkable changes in the reflectance peak.

  18. Roaming-mediated ultrafast isomerization of geminal tri-bromides in the gas and liquid phases.

    PubMed

    Mereshchenko, Andrey S; Butaeva, Evgeniia V; Borin, Veniamin A; Eyzips, Anna; Tarnovsky, Alexander N

    2015-07-01

    'Roaming' is a new and unusual class of reaction mechanism that has recently been discovered in unimolecular dissociation reactions of isolated molecules in the gas phase. It is characterized by frustrated bond cleavage, after which the two incipient fragments 'roam' on a flat region of the potential energy surface before reacting with one another. Here, we provide evidence that supports roaming in the liquid phase. We are now able to explain previous solution-phase experiments by comparing them with new ultrafast transient absorption data showing the photoisomerization of gas-phase CHBr3. We see that, upon S0-S1 excitation, gas-phase CHBr3 isomerizes within 100?fs into the BrHCBr-Br species, which is identical to what has been observed in solution. Similar sub-100 fs isomerization is now also observed for BBr3 and PBr3 in solution upon S1 excitation. Quantum chemical simulations of XBr3 (X?=?B, P or CH) suggest that photochemical reactivity in all three cases studied is governed by S1/S0 conical intersections and can best be described as occurring through roaming-mediated pathways. PMID:26100804

  19. Processing and fabrication of mixed uranium/refractory metal carbide fuels with liquid-phase sintering

    NASA Astrophysics Data System (ADS)

    Knight, Travis W.; Anghaie, Samim

    2002-11-01

    Optimization of powder processing techniques were sought for the fabrication of single-phase, solid-solution mixed uranium/refractory metal carbide nuclear fuels - namely (U, Zr, Nb)C. These advanced, ultra-high temperature nuclear fuels have great potential for improved performance over graphite matrix, dispersed fuels tested in the Rover/NERVA program of the 1960s and early 1970s. Hypostoichiometric fuel samples with carbon-to-metal ratios of 0.98, uranium metal mole fractions of 5% and 10%, and porosities less than 5% were fabricated. These qualities should provide for the longest life and highest performance capability for these fuels. Study and optimization of processing methods were necessary to provide the quality assurance of samples for meaningful testing and assessment of performance for nuclear thermal propulsion applications. The processing parameters and benefits of enhanced sintering by uranium carbide liquid-phase sintering were established for the rapid and effective consolidation and formation of a solid-solution mixed carbide nuclear fuel.

  20. Advanced far infrared blocked impurity band detectors based on germanium liquid phase epitaxy

    SciTech Connect

    Olsen, C S [Lawrence Berkeley National Lab., CA (United States). Engineering Div.

    1998-05-01

    This research has shown that epilayers with residual impurity concentrations of 5 x 10{sup 13} cm{sup {minus}3} can be grown by producing the purest Pb available in the world. These epilayers have extremely low minority acceptor concentrations, which is ideal for fabrication of IR absorbing layers. The Pb LPE growth of Ge also has the advantageous property of gettering Cu from the epilayer and the substrate. Epilayers have been grown with intentional Sb doping for IR absorption on lightly doped substrates. This research has proven that properly working Ge BIB detectors can be fabricated from the liquid phase as long as pure enough solvents are available. The detectors have responded at proper wavelengths when reversed biased even though the response did not quite reach minimum wavenumbers. Optimization of the Sb doping concentration should further decrease the photoionization energy of these detectors. Ge BIB detectors have been fabricated that respond to 60 cm{sup {minus}1} with low responsivity. Through reduction of the minority residual impurities, detector performance has reached responsivities of 1 A/W. These detectors have exhibited quantum efficiency and NEP values that rival conventional photoconductors and are expected to provide a much more sensitive tool for new scientific discoveries in a number of fields, including solid state studies, astronomy, and cosmology.

  1. Analysis of Protein Glycosylation and Phosphorylation Using Liquid Phase Separation, Protein Microarray Technology, and Mass Spectrometry

    PubMed Central

    Zhao, Jia; Patwa, Tasneem H.; Pal, Manoj; Qiu, Weilian; Lubman, David M.

    2010-01-01

    Summary Protein glycosylation and phosphorylation are very common posttranslational modifications. The alteration of these modifications in cancer cells is closely related to the onset and progression of cancer and other disease states. In this protocol, strategies for monitoring the changes in protein glycosylation and phosphorylation in serum or tissue cells on a global scale and specifically characterizing these alterations are included. The technique is based on lectin affinity enrichment for glycoproteins, all liquid-phase two-dimensional fractionation, protein microarray, and mass spectrometry technology. Proteins are separated based on pI in the first dimension using chromatofocusing (CF) or liquid isoelectric focusing (IEF) followed by the second-dimension separation using nonporous silica RP-HPLC. Five lectins with different binding specificities to glycan structures are used for screening glycosylation patterns in human serum through a biotin–streptavidin system. Fluorescent phosphodyes and phosphospecific antibodies are employed to detect specific phosphorylated proteins in cell lines or human tissues. The purified proteins of interest are identified by peptide sequencing. Their modifications including glycosylation and phosphorylation could be further characterized by mass-spectrometry-based approaches. These strategies can be used in biological samples for large-scale glycoproteome/phosphoproteome screening as well as for individual protein modification analysis. PMID:19241043

  2. Investigating the solid-liquid phase transition of water nanofilms using the generalized replica exchange method

    SciTech Connect

    Lu, Qing [Division of Materials Science and Engineering, Boston University, Brookline, Massachusetts 02446 (United States); Kim, Jaegil; Straub, John E., E-mail: straub@bu.edu [Department of Chemistry, Boston University, Boston, Massachusetts 02215 (United States); Farrell, James D.; Wales, David J. [University Chemical Laboratories, Lensfield Road, Cambridge CB2 1EW (United Kingdom)

    2014-11-14

    The generalized Replica Exchange Method (gREM) was applied to study a solid-liquid phase transition in a nanoconfined bilayer water system using the monatomic water (mW) model. Exploiting optimally designed non-Boltzmann sampling weights with replica exchanges, gREM enables an effective sampling of configurations that are metastable or unstable in the canonical ensemble via successive unimodal energy distributions across phase transition regions, often characterized by S-loop or backbending in the statistical temperature. Extensive gREM simulations combined with Statistical Temperature Weighted Histogram Analysis Method (ST-WHAM) for nanoconfined mW water at various densities provide a comprehensive characterization of diverse thermodynamic and structural properties intrinsic to phase transitions. Graph representation of minimized structures of bilayer water systems determined by the basin-hopping global optimization revealed heterogeneous ice structures composed of pentagons, hexagons, and heptagons, consistent with an increasingly ordered solid phase with decreasing density. Apparent crossover from a first-order solid-liquid transition to a continuous one in nanoconfined mW water with increasing density of the system was observed in terms of a diminishing S-loop in the statistical temperature, smooth variation of internal energies and heat capacities, and a characteristic variation of lateral radial distribution functions, and transverse density profiles across transition regions.

  3. ac susceptibility measurement of magnetic markers in suspension for liquid phase immunoassay

    NASA Astrophysics Data System (ADS)

    Enpuku, K.; Tamai, Y.; Mitake, T.; Yoshida, T.; Matsuo, M.

    2010-08-01

    ac susceptibility measurement of magnetic markers in solution was performed for the liquid phase detection of biological targets. First, the properties of the magnetic markers were clarified, such as size distribution, frequency dependence of susceptibility, and field dependence of magnetization. Next, we demonstrated a detection method in which we used large polymer beads to immobilize and prolong the Brownian relaxation time of the bound markers. In this method, we could detect the bound markers by the decrease in the susceptibility that they displayed. Using this method, we detected biotin-conjugated polymer beads with avidin-coated Fe3O4 markers. Changes in susceptibility caused by the binding reaction between them were measured with a magnetoresistive sensor. A strong relationship was observed between the decrease in susceptibility and the number of polymer beads, which indicates that the bound markers were detected correctly without the use of the washing process called bound/free separation. The sensitivity of the system was estimated to be as high as 1.3×10-16 mol/ml in terms of the molecular-number concentration of the markers. The binding process was also discussed from the dependence of the signal on the incubation time.

  4. Liquid-liquid phase transition in quasi-two-dimensional supercooled silicon.

    PubMed

    Zhang, K; Li, H; Jiang, Y Y

    2014-09-01

    Anomalies of the local structural order in quasi-two-dimensional liquid silicon upon cooling are investigated. Results show that the appearance of the left subpeak in pair correlation functions is the signature of the liquid-liquid phase transition (LLPT). The structural origin of the LLPT is the formation of a crystal-like ordered structure with a short-range scale, which in turn forms the local well-organized paracrystalline region. Unlike in the bulk liquid silicon, the stages of the LLPT and liquid-solid phase transition (LSPT) in the quasi-two-dimensional liquid silicon do not overlap. The crystal-like ordered structures formed in the LLPT are precursors which are prepared for the subsequent LSPT. Also observed was a strong interconnection between the local well-organized paracrystalline region and the transition from the typical metal to the semimetal in the two-dimensional silicon. This study will aid in better understanding of the essential phase change in two-dimensional liquid silicon. PMID:25050842

  5. "Liquid-phase calcination" of colloidal mesoporous silica nanoparticles in high-boiling solvents.

    PubMed

    Cauda, Valentina; Argyo, Christian; Piercey, Davin G; Bein, Thomas

    2011-05-01

    We report on a novel high temperature liquid phase "calcination" method with trioctylphosphine oxide (TOPO), tri-n-octylamine (TOA), and squalene for removing the template and strengthening the silica network in colloidal mesoporous silica (CMS) nanoparticles. For such materials, the common calcination procedure in air would result in strong agglomeration, thus preventing their use in colloidal suspensions. The highest efficiency of the new approach is obtained by thermal calcination in TOPO at only 275 °C, as shown by an increasing degree of silica condensation, and the retention of the high colloidal stability of the CMS nanoparticles. Moreover, we also show the ability of the TOPO treatment to remove the template, thus saving a preparation step. The resulting CMS nanoparticles retain the ordered mesostructure, high porosity, and large surface area of the original mesoporous nanoparticles, while showing a much greater degree of silica condensation and high stability. The concept of "liquid calcination" represents a powerful general approach for the preparation of stable colloidal porous nanoparticles. PMID:21480591

  6. Roaming-mediated ultrafast isomerization of geminal tri-bromides in the gas and liquid phases

    NASA Astrophysics Data System (ADS)

    Mereshchenko, Andrey S.; Butaeva, Evgeniia V.; Borin, Veniamin A.; Eyzips, Anna; Tarnovsky, Alexander N.

    2015-07-01

    ‘Roaming’ is a new and unusual class of reaction mechanism that has recently been discovered in unimolecular dissociation reactions of isolated molecules in the gas phase. It is characterized by frustrated bond cleavage, after which the two incipient fragments ‘roam’ on a flat region of the potential energy surface before reacting with one another. Here, we provide evidence that supports roaming in the liquid phase. We are now able to explain previous solution-phase experiments by comparing them with new ultrafast transient absorption data showing the photoisomerization of gas-phase CHBr3. We see that, upon S0–S1 excitation, gas-phase CHBr3 isomerizes within 100?fs into the BrHCBr–Br species, which is identical to what has been observed in solution. Similar sub-100 fs isomerization is now also observed for BBr3 and PBr3 in solution upon S1 excitation. Quantum chemical simulations of XBr3 (X?=?B, P or CH) suggest that photochemical reactivity in all three cases studied is governed by S1/S0 conical intersections and can best be described as occurring through roaming-mediated pathways.

  7. Influence of cooling rate on the liquid-phase epitaxial growth of Zn 3P 2

    NASA Astrophysics Data System (ADS)

    Sudhakar, S.; Baskar, K.

    2008-05-01

    We report the liquid-phase epitaxial growth of Zn 3P 2 on InP (1 0 0) substrates by conventional horizontal sliding boat system using 100% In solvent. Different cooling rates of 0.2-1.0 °C/min have been adopted and the influence of supercooling on the properties of the grown epilayers is analyzed. The crystal structure and quality of the grown epilayers have been studied by X-ray diffraction and high-resolution X-ray rocking measurements, which revealed a good lattice matching between the epilayers and the substrate. The supercooling-induced morphologies and composition of the epilayers were studied by scanning electron microscopy and energy dispersive X-ray analysis. The growth rate has been calculated and found that there exists a linear dependence between the growth rate and the cooling rate. Hall measurements showed that the grown layers are unintentionally doped p-type with a carrier mobility as high as 450 cm 2/V s and a carrier concentration of 2.81×10 18 cm -3 for the layers grown from 6 °C supercooled melt from the cooling rate of 0.4 °C/min.

  8. Liquid phase epitaxial growth of II V semiconductor compound Zn3As2

    NASA Astrophysics Data System (ADS)

    Sudhakar, S.; Ganesh, V.; Sulania, Indra; Kulriya, Pawan K.; Baskar, K.

    2007-09-01

    We report the liquid phase epitaxial growth of Zn3As2 on InAs (1 1 0) substrates using 100% In solvent. The zinc concentration in the layers was varied by changing the zinc mole fraction in the growth melt from 3 × 10-3 to 15 × 10-3, keeping all other growth parameters constant. Layers grown with 3 × 10-3, 5 × 10-3 and 8 × 10-3 mole fractions of zinc seem to be polycrystalline, while layers grown with more than 8 × 10-3 mole fraction of zinc resulted in highly oriented and single crystalline material. Composition of the epilayers was confirmed by energy dispersive x-ray microanalysis. Scanning electron microscopy was used to determine the thickness of the epilayers and the growth rate was calculated. Furthermore it was found that a linear dependence exists between the growth rate and the zinc mole fraction in the growth melt. Atomic force microscopy results reveal that the smoothness of the epilayers improve when the zinc concentration in the epilayer approaches the stoichiometric value of Zn3 As2. Room temperature Hall measurements showed that the grown epilayers were unintentionally doped p-type with an increase in the carrier mobility and a decrease in the carrier concentration with respect to the increase in the zinc mole fraction in the growth melt.

  9. Modern Evaluation of Liquisolid Systems with Varying Amounts of Liquid Phase Prepared Using Two Different Methods

    PubMed Central

    Vetchý, David

    2015-01-01

    Liquisolid systems are an innovative dosage form used for enhancing dissolution rate and improving in vivo bioavailability of poorly soluble drugs. These formulations require specific evaluation methods for their quality assurance (e.g., evaluation of angle of slide, contact angle, or water absorption ratio). The presented study is focused on the preparation, modern in vitro testing, and evaluation of differences of liquisolid systems containing varying amounts of a drug in liquid state (polyethylene glycol 400 solution of rosuvastatin) in relation to an aluminometasilicate carrier (Neusilin US2). Liquisolid powders used for the formulation of final tablets were prepared using two different methods: simple blending and spraying of drug solution onto a carrier in fluid bed equipment. The obtained results imply that the amount of liquid phase in relation to carrier material had an effect on the hardness, friability, and disintegration of tablets, as well as their height. The use of spraying technique enhanced flow properties of the prepared mixtures, increased hardness values, decreased friability, and improved homogeneity of the final dosage form.

  10. Gas-Purged Headspace Liquid Phase Microextraction System for Determination of Volatile and Semivolatile Analytes

    PubMed Central

    Zhang, Meihua; Bi, Jinhu; Yang, Cui; Li, Donghao; Piao, Xiangfan

    2012-01-01

    In order to achieve rapid, automatic, and efficient extraction for trace chemicals from samples, a system of gas-purged headspace liquid phase microextraction (GP-HS-LPME) has been researched and developed based on the original HS-LPME technique. In this system, semiconductor condenser and heater, whose refrigerating and heating temperatures were controlled by microcontroller, were designed to cool the extraction solvent and to heat the sample, respectively. Besides, inert gas, whose gas flow rate was adjusted by mass flow controller, was continuously introduced into and discharged from the system. Under optimized parameters, extraction experiments were performed, respectively, using GP-HS-LPME system and original HS-LPME technique for enriching volatile and semivolatile target compounds from the same kind of sample of 15 PAHs standard mixture. GC-MS analysis results for the two experiments indicated that a higher enrichment factor was obtained from GP-HS-LPME. The enrichment results demonstrate that GP-HS-LPME system is potential in determination of volatile and semivolatile analytes from various kinds of samples. PMID:22448341

  11. Quasielastic neutron scattering measurements of n -butane in its crystalline, plastic, and liquid phases

    SciTech Connect

    Bradley, K.F. (Nuclear Engineering Department, Massachusetts Institute of Technology, Cambridge, Massachusetts (USA)); Chen, S. (Nuclear Engineering Department and Center for Materials Science Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts (USA)); Brun, T.O. (LANSCE, Los Alamos National Laboratory, Los Alamos, New Mexico (USA))

    1991-10-01

    We report here measurements of quasielastic neutron scattering from {ital n}-butane at temperatures of 90, 115, 125 and 190 K and in a momentum transfer range of 0.8--2.4 A{sup {minus}1}. These measurements confirm that between 115 and 125 K butane forms a plastic crystal in which the centers of mass of the butane molecules form a crystalline structure, but the individual molecules are free to rotate. At these two intermediate temperatures, there exists both an elastic peak, characteristic of a solid structure, and quasielastic components arising from the rotational motions of the butane molecules. At 90 K, the butane scatters neutrons only elastically, while at 190 K, the butane scatters neutrons only quasielastically. In both the plastic and the liquid phases, the presence of at least two quasielastic processes must be assumed in order to explain the measurements. In the plastic crystal, we associate a broad Lorentzian component with intramolecular reorientations about the central carbon--carbon bond and a second, relatively narrow, Lorentzian component with whole molecule rotations.

  12. Multi-colorimetric sensor array for detection of explosives in gas and liquid phase

    NASA Astrophysics Data System (ADS)

    Kostesha, N.; Alstrøm, T. S.; Johnsen, C.; Nielsen, K. A.; Jeppesen, J. O.; Larsen, J.; Boisen, A.; Jakobsen, M. H.

    2011-05-01

    In the framework of the research project "Xsense" at the Technical University of Denmark (DTU) we are developing a simple colorimetric sensor array which can be useful in detection of explosives like DNT, TATP, HMX, RDX and identification of reagents needed for making homemade explosives. The technology is based on an array of chemoselective compounds immobilized on a solid support. Upon exposure to the analyte in suspicion the colorimetric array changes color. Each chosen compound reacts chemo-selectively with analytes of interest. A change in a color signature indicates the presence of unknown explosives and volatile organic compounds (VOCs). We are working towards the selection of compounds that undergo color changes in the presence of explosives and VOCs, as well as the development of an immobilization method for the molecules. Digital imaging of the colorimetric array before and after exposure to the analytes creates a color difference map which gives a unique fingerprint for each explosive and VOCs. Such sensing technology can be used for screening relevant explosives in a complex background as well as to distinguish mixtures of volatile organic compounds distributed in gas and liquid phases. This sensor array is inexpensive, and can potentially be produced as single use disposable.

  13. Modern Evaluation of Liquisolid Systems with Varying Amounts of Liquid Phase Prepared Using Two Different Methods.

    PubMed

    Vraníková, Barbora; Gajdziok, Jan; Vetchý, David

    2015-01-01

    Liquisolid systems are an innovative dosage form used for enhancing dissolution rate and improving in vivo bioavailability of poorly soluble drugs. These formulations require specific evaluation methods for their quality assurance (e.g., evaluation of angle of slide, contact angle, or water absorption ratio). The presented study is focused on the preparation, modern in vitro testing, and evaluation of differences of liquisolid systems containing varying amounts of a drug in liquid state (polyethylene glycol 400 solution of rosuvastatin) in relation to an aluminometasilicate carrier (Neusilin US2). Liquisolid powders used for the formulation of final tablets were prepared using two different methods: simple blending and spraying of drug solution onto a carrier in fluid bed equipment. The obtained results imply that the amount of liquid phase in relation to carrier material had an effect on the hardness, friability, and disintegration of tablets, as well as their height. The use of spraying technique enhanced flow properties of the prepared mixtures, increased hardness values, decreased friability, and improved homogeneity of the final dosage form. PMID:26075249

  14. Dye Assisted-Optical Lithography of Polymers from Liquid-Phase

    NASA Astrophysics Data System (ADS)

    Sileshi, Redahegn; Taguenang, Jean-Mishel; Calzzani, Fernando; Kassu, Aschalew; Sharma, Anup

    2008-10-01

    There has been much recent interest in polymeric materials for holographic gratings in the field of information storage, wave guide coupling, and non linear optoelectronics. Polybutadiene which is synthetic rubber is biologically benign and used in making it attractive as a platform for biomolecular applications. NBD dye assisted optical Lithography of polybutadiene polymers from liquid phase is our main interest here .aqueous solution of NBD (NBD dissolved in distilled water having various concentration) is confined between two polybutadiene coated glass substrate. The aqueous solution is contact with the coated surface. The two glass substrates are separated by a spacer which provide enough space for the molecules to move and rearrange themselves. Interferometery of two coherent beams derived from the 488 nm Argon-ion laser excites the dye. Formation of the grating is due to the laser excited dye with a polymer on the substrate. Dependency of light diffraction efficiency on the concentration of the aqueous solutions as well as intensity of the laser will be investigated. The interesting phenomenon in this technique is following a short initial exposure the grating continues to grow for several time after the beam is blocked.

  15. Synthesis of structurally well-defined and liquid-phase-processable graphene nanoribbons

    NASA Astrophysics Data System (ADS)

    Narita, Akimitsu; Feng, Xinliang; Hernandez, Yenny; Jensen, Søren A.; Bonn, Mischa; Yang, Huafeng; Verzhbitskiy, Ivan A.; Casiraghi, Cinzia; Hansen, Michael Ryan; Koch, Amelie H. R.; Fytas, George; Ivasenko, Oleksandr; Li, Bing; Mali, Kunal S.; Balandina, Tatyana; Mahesh, Sankarapillai; de Feyter, Steven; Müllen, Klaus

    2014-02-01

    The properties of graphene nanoribbons (GNRs) make them good candidates for next-generation electronic materials. Whereas ‘top-down’ methods, such as the lithographical patterning of graphene and the unzipping of carbon nanotubes, give mixtures of different GNRs, structurally well-defined GNRs can be made using a ‘bottom-up’ organic synthesis approach through solution-mediated or surface-assisted cyclodehydrogenation reactions. Specifically, non-planar polyphenylene precursors were first ‘built up’ from small molecules, and then ‘graphitized’ and ‘planarized’ to yield GNRs. However, fabrication of processable and longitudinally well-extended GNRs has remained a major challenge. Here we report a bottom-up solution synthesis of long (>200 nm) liquid-phase-processable GNRs with a well-defined structure and a large optical bandgap of 1.88 eV. Self-assembled monolayers of GNRs can be observed by scanning probe microscopy, and non-contact time-resolved terahertz conductivity measurements reveal excellent charge-carrier mobility within individual GNRs. Such structurally well-defined GNRs may prove useful for fundamental studies of graphene nanostructures, as well as the development of GNR-based nanoelectronics.

  16. Disorder Induced Nonlinear Dynamics in the Vortex Liquid Phase of YBCO

    NASA Astrophysics Data System (ADS)

    Crabtree, George; Kwok, Wai-Kwong; Olsson, Robert; Karapetrov, Goran; Hofman, David; Paulius, Lisa; Moulton, William

    2000-03-01

    We report a new region of nonlinear I-V curves in the vortex liquid state of untwinned YBCO containing heavy ion induced line defects. Crystals irradiated with 1.4 GeV Pb ions to a dose matching field of 1000 G show a clear lower critical point at 4 T. Below the lower critical point there is a Bose glass transition from the vortex liquid to the solid. The lower critical point marks the changeover from the continuous Bose glass transition to the conventional first order melting of the lattice. A new region of nonlinear I-V curves occurs in the liquid phase just above the first order melting transition of the lattice. This nonlinear regime merges smoothly with the critical region surrounding the Bose glass transition below the lower critical point, and extends to at least 8 T. Systematic studies as a function of dose matching field suggest that the nonlinear region is correlated with a shift of the upper critical point by line defects. Work supported by DOE BES-MS, under contract #W-31-109-ENG-38 (GWC, WKK, RJO, LMP, DH), and by the NSF Science and Technology Center under contract #DMR20000(GK).

  17. CTU Optical probes for liquid phase detection in the 1000 MW steam turbine

    NASA Astrophysics Data System (ADS)

    Kolovratník, Michal; Bartoš, Ond?ej

    2015-05-01

    The aim of this paper is to introduce the measurement capacity of a new generation of CTU's optical probes to determine the liquid phase distribution in steam turbines and other energy systems. At the same time the paper presents the first part of the results concerning output wetness achieved through the use of experimental research performed with the probes in a new low pressure (LP) part of the steam turbine 1000MW in the Temelin nuclear power plant (ETE). Two different probes were used. A small size extinction probe with a diameter of 25mm which was developed for measuring in a wider range of turbines in comparison with the previous generation with a diameter of 50mm. The second probe used was a photogrammetric probe developed to observe the coarse droplets. This probe is still under development and this measurement was focused on verifying the capabilities of the probe. The data processing technique is presented together with yielded examples of the wetness distribution along the last blade of the 1000MW steam turbine. The experimental measurement was done in cooperation with Doosan Škoda Power s.r.o. (DSP).

  18. Microporous hydrophobic hollow fiber modules for gas-liquid phase separation in microgravity

    NASA Astrophysics Data System (ADS)

    Noyes, Gary

    Gas-liquid interphase mass transfer operations, such as gas-liquid phase separation, gas absorption into liquid or dissolved gas separation from liquid, gas humidification and drying via liquid contact, and evaporative cooling are readily accomplished on the Earth with settling/spray chambers, packed towers, or bubble columns. This paper reports on gas-water mass transfer tests performed utilizing microporous hydrophobic Hollow Fiber Modules (HFMs) of the type currently employed as blood oxygenators in heart-lung machines. In these HFMs, gases are transferrred to and from water or other hydrophilic liquids through the microporous fiber walls; liquid water does not enter the pores of the highly hydrophobic wall material. The experiments included air-water phase separation, absorption of oxygen and carbon dioxide into water and separation of these dissolved gases from water, air humidification and drying by contact with temperature-controlled water, and controlled evaporation of water into a vacuum. In each of these experiments, a small, light HFM sucessfully performed the mass tranfer function, with no leakage of liquid water through the porous walls of the hollow fibers, even with high pressure across the fiber wall for extended periods of time. These results demonstrate that gas-liquid mass transfer unit operations on hydrophilic liquids, implemented with microporous hydrophobic HFM technology, are ready for use in microgravity fluid processing systems.

  19. Redistribution of black carbon in aerosol particles undergoing liquid-liquid phase separation

    NASA Astrophysics Data System (ADS)

    Brunamonti, Simone; Krieger, Ulrich K.; Marcolli, Claudia; Peter, Thomas

    2015-04-01

    Atmospheric black carbon (BC) is a major anthropogenic greenhouse agent, yet substantial uncertainties obstruct understanding its radiative forcing. Particularly debated is the extent of the absorption enhancement by internally compared to externally mixed BC, which critically depends on the interior morphology of the BC-containing particles. Here we suggest that a currently unaccounted morphology, optically very different from the customary core-shell and volume-mixing assumptions, likely occurs in aerosol particles undergoing liquid-liquid phase separation (LLPS). Using Raman spectroscopy on micrometer-sized droplets, we show that LLPS of an organic/inorganic model system drives redistribution of BC into the outer (organic) phase of the host particle. This results in an inverted core-shell structure, in which a transparent aqueous core is surrounded by a BC-containing absorbing shell. Based on Mie theory calculations, we estimate that such a redistribution can reduce the absorption efficiency of internally-mixed BC aerosols by up to 25% compared to the volume-mixing approximation.

  20. Redistribution of black carbon in aerosol particles undergoing liquid-liquid phase separation

    NASA Astrophysics Data System (ADS)

    Brunamonti, S.; Krieger, U. K.; Marcolli, C.; Peter, T.

    2015-04-01

    Atmospheric black carbon (BC) is a major anthropogenic greenhouse agent, yet substantial uncertainties obstruct understanding its radiative forcing. Particularly debated is the extent of the absorption enhancement by internally compared to externally mixed BC, which critically depends on the interior morphology of the BC-containing particles. Here we suggest that a currently unaccounted morphology, optically very different from the customary core-shell and volume-mixing assumptions, likely occurs in aerosol particles undergoing liquid-liquid phase separation (LLPS). Using Raman spectroscopy on micrometer-sized droplets, we show that LLPS of an organic/inorganic model system drives redistribution of BC into the outer (organic) phase of the host particle. This results in an inverted core-shell structure, in which a transparent aqueous core is surrounded by a BC-containing absorbing shell. Based on Mie theory calculations, we estimate that such a redistribution can increase the absorption efficiency of internally mixed BC aerosols by up to 25% compared to the core-shell approximation.

  1. Transient liquid phase metallic bonding of an Inconel 718SPF superalloy

    SciTech Connect

    Yeh, M.S. [Chung-Hua Polytechnic Inst., Hsin-Chu (Taiwan, Province of China). Dept. of Mechanical Engineering; Chuang, T.H. [National Taiwan Univ., Taipei (Taiwan, Province of China). Inst. of Materials Science and Engineering

    1997-12-01

    The applicability of the transient liquid phase (TLP) metallic bonding method for joining fine-grained Inconel 718SPF{reg_sign} superalloy sheets by inserting a Ni-P or a Ni-Cr-P amorphous interlayer has been evaluated. The results show that a joint with uniform chemical composition could be obtained for the Inconel 718SPF superalloy with a Ni-P interlayer at 1,100 C for 8 h. When a Ni-Cr-P interlayer was used under the same metallic bonding conditions, the concentrations of nickel, iron and niobium in the bond region and in the base metal had a difference of more than 2 wt-%. This means that longer bonding time was required to homogenize the chemical compositions of bonds with a Ni-Cr-P interlayer. The joints with a Ni-P interlayer showed higher bond strength than did those with a Ni-Cr-P interlayer. Furthermore, many grain boundary precipitates were found.

  2. Kinetics of the aerobic biological degradation of shredded municipal solid waste in liquid phase.

    PubMed

    Liwarska-Bizukojc, Ewa; Bizukojc, Marcin; Ledakowicz, Stanislaw

    2002-04-01

    The organic fraction of municipal solid waste (OFMSW) should be utilised by means of biological methods. The biodegradation of solid wastes can be intensified owing to application of the bioreactors. Estimation of the optimum values of the organic load is one of the most important tasks for the aerobic biodegradation processes. The kinetic model of biological oxidation of the organic wastes has been presented in this paper. The experiments were carried out in batch 6-l working volume stirred tank bioreactors at constant temperature of 25 degrees C. Initial total solids have been at the levels of 15, 19, 34, 55 and 66 g l(-1). The kinetics of microbial decomposition of organic substances was described by means of an unstructured model. The satisfactory time courses for substrate chemical oxygen demand in the solid (CODs) and liquid phase (CODL) and biomass concentration (RNA) have been achieved. Also, the influence of the initial TS on the kinetics of the biodegradation process was investigated and the optimum value of initial TS for this type of processes was estimated at 34-55 g l(-1). PMID:12092587

  3. Preparation of fluorinated gate oxides by liquid phase deposition following rapid thermal oxidation

    NASA Astrophysics Data System (ADS)

    Lu, Wei-Shin; Hwu, Jenn-Gwo

    1995-06-01

    The fluorinated gate oxides grown by the method of liquid phase deposition (LPD) following rapid thermal oxidation (RTO) were studied in this work. Samples with and without aluminum are both investigated in the LPD process. It was found that the amount of F atoms decreases as the LPD oxide was treated subsequently by RTO treatment. For a given time of RTO, the longer the LPD time, the larger the amount of F contained in the gate oxides. But for a given time of LPD, the longer the RTO time, the smaller the amount of F contained in the gate oxides. It was found that the radiation induced oxide charge number density shift ?Not and the midgap interface trap density shift ?Ditm, and the oxide breakdown field Eox exhibit turnaround dependencies on the LPD growth time. In other words, they are dependent on the amount of F atoms incorporated into the gate oxide. Interestingly, it was found that for the gate oxides grown by the LPD process containing Al have better quality than the LPD without containing Al from the viewpoint of radiation hardness and electric breakdown field.

  4. Analysis of quinolones by voltage-assisted liquid-phase microextraction combined with LC-MS.

    PubMed

    Wang, Mi-Hung; Wang, Shu-Ping

    2012-03-01

    The method of liquid-phase microextraction assisted with voltage was developed and applied on determination of quinolones in water sample in this study. Both of the reproducibility and extraction time were improved with the aid of applying voltage. Four analytes in neutral state such as cinoxacin, oxolinic acid, nalidixic acid, and flumequine were extracted from a sample solution at pH 2.0, through a polypropylene hollow fiber which was immobilized with 2-octanone, and then into a 25 ?L of the acceptor phase of 40 mM borate buffer at pH 10.0 by applying voltage of 100 V. Subsequently, the acceptor solution was directly subjected to analysis by LC-MS. The performance of the method for four quinolones was also evaluated. Linearity was obtained in the range of 1.0-25.0 ng/mL with R(2) > 0.996. Limits of detection were below 0.6 ng/mL, and recoveries of water sample were ranged from 90.8 to 109.6%. PMID:22517642

  5. Liquid phase epitaxy of binary III-V nanocrystals in thin Si layers triggered by ion implantation and flash lamp annealing

    NASA Astrophysics Data System (ADS)

    Wutzler, Rene; Rebohle, Lars; Prucnal, Slawomir; Bregolin, Felipe L.; Hübner, Rene; Voelskow, Matthias; Helm, Manfred; Skorupa, Wolfgang

    2015-05-01

    The integration of III-V compound semiconductors in Si is a crucial step towards faster and smaller devices in future technologies. In this work, we investigate the formation process of III-V compound semiconductor nanocrystals, namely, GaAs, GaSb, and InP, by ion implantation and sub-second flash lamp annealing in a SiO2/Si/SiO2 layer stack on Si grown by plasma-enhanced chemical vapor deposition. Raman spectroscopy, Rutherford Backscattering spectrometry, and transmission electron microscopy were performed to identify the structural and optical properties of these structures. Raman spectra of the nanocomposites show typical phonon modes of the compound semiconductors. The formation process of the III-V compounds is found to be based on liquid phase epitaxy, and the model is extended to the case of an amorphous matrix without an epitaxial template from a Si substrate. It is shown that the particular segregation and diffusion coefficients of the implanted group-III and group-V ions in molten Si significantly determine the final appearance of the nanostructure and thus their suitability for potential applications.

  6. Determination of lewisite constituents in aqueous samples using hollow-fibre liquid-phase microextraction followed by gas chromatography-mass spectrometry.

    PubMed

    Cheh, M Y; Chua, H C; Hopkins, F B; Riches, J R; Timperley, C M; Lee, H S Nancy

    2014-08-01

    The applicability of hollow-fibre liquid-phase microextraction for extracting 2-chlorovinyldichloroarsine (lewisite 1), bis(2-chlorovinyl)chloroarsine (lewisite 2), tris(2-chlorovinyl)arsine (lewisite 3) and arsenic trichloride from aqueous samples is reported. Parameters affecting the extraction efficiency of these chemicals were optimised. These parameters included the type of derivatising agent, extraction solvent, derivatisation method, pH, ionic strength, stirring speed and extraction time. A linear range between 0.002 and 0.2 ?g/mL was established for the lewisites with good square regression coefficients (0.9955-0.9992). Good reproducibility with relative standard deviations (RSDs) from 8 to 10% was achieved. The limit of detection was 0.002 ?g/mL for the lewisites and 0.005 ?g/mL for arsenic trichloride (3:1 signal-to-noise ratio). The extraction method was validated with a proficiency test sample issued by the Organisation for the Prohibition of Chemical Weapons (OPCW). The rapidity and precision of the new method should help deter against the employment of lewisite as a chemical warfare agent: its use could be confirmed easily from analysis of aqueous samples. PMID:24633588

  7. Liquid Phase Sintering and Microwave Dielectric Properties of Ba(Mg1/3Ta2/3)O3 Ceramics

    NASA Astrophysics Data System (ADS)

    Huang, Cheng-Liang; Lin, Ruei-Jsung

    2002-02-01

    The effect of CuO addition on the microstructures and the microwave dielectric properties of barium magnesium tantalate Ba(Mg1/3Ta2/3)O3 ceramics has been investigated. It is found that low level-doping of CuO (up to 1 wt%) can significantly improve the density of the specimens and their microwave dielectric properties. The density of doped Ba(Mg1/3Ta2/3)O3 ceramics can be increased beyond 96% of its theoretical density by at sintering 1440°C due to the liquid phase effect of CuO addition observed by scanning electron microscopy. The second phase was not observed for ceramics with 0.25 to1 wt% CuO additions. The dielectric constant (\\varepsilonr) and temperature coefficient of resonant frequency (?f) were not significantly affected, while the nonloaded quality factors Q were effectively promoted by CuO addition. The \\varepsilonr value of 24.2, Q× f value of 173000 (at 10 GHz) and ?f value of 1.5 ppm/°C were obtained for Ba(Mg1/3Ta2/3)O3 ceramics with 0.5 wt% CuO addition sintered at 1470°C for 4 h.

  8. Infinite dilution activity coefficients for benzene and toluene in water and in aqueous solutions of the protein denaturants urea and guanidine hydrochloride

    Microsoft Academic Search

    Miguel Costas

    2000-01-01

    Experimental infinite dilution activity coefficients?1? for benzene and toluene in water and in aqueous solutions of two protein denaturants, urea and guanidine hydrochloride, are reported. The quantities were measured in the temperature range (273 to 323) K. Four denaturant concentrations were used from (0.5 to 5.0)mol · dm?3, covering the range where proteins undergo chemical denaturation. For both solutes in

  9. DETERMINATION OF ACTIVITY COEFFICIENTS USING A FLOW EMF METHOD. 2. NaCl-K2SO4-H2O SYSTEM

    E-print Network

    Zhang, Luzheng

    #12;DETERMINATION OF ACTIVITY COEFFICIENTS USING A FLOW EMF METHOD. 2. NaCl-K2SO4-H2O SYSTEM AT 298 electrolyte in mixed solvent rapidly. The EMF data for the ternary system NaCl(1)-K2SO4(2)-H2O(3) without aqueous solution with a common anion, NaCl-KCl-H2O system, at 298.15K [7]. In this work, the flow method

  10. Activity coefficient at infinite dilution, azeotropic data, excess enthalpies and solid–liquid-equilibria for binary systems of alkanes and aromatics with esters

    Microsoft Academic Search

    Eileen Collinet; Jürgen Gmehling

    2005-01-01

    Binary azeotropic data have been measured at different pressures for ethyl acetate+heptane, methyl acetate+heptane, isopropyl acetate+hexane and isopropyl acetate+heptane by means of a wire band column. Additionally activity coefficients at infinite dilution have been determined for ethyl acetate and isopropyl acetate in decane and dodecane in the temperature range between 303.15 and 333.15K with the help of the dilutor technique.

  11. Measurement of activity coefficients at infinite dilution in N-methyl-2-pyrrolidone and N-formylmorpholine and their mixtures with water using the dilutor technique

    Microsoft Academic Search

    Michael Krummen; Jürgen Gmehling

    2004-01-01

    With the help of the dilutor technique activity coefficients at infinite dilution have been measured for 24 solutes (alkanes, alkenes, cyclic hydrocarbons, aromatic hydrocarbons, ketones, ethers and alcohols) in N-methyl-2-pyrrolidone (NMP), N-formylmorpholine (NFM) and their mixtures with water in the temperature range between 303.15 and 333.15K (in a few cases for temperatures up to 423.15K). The influence of water on

  12. Vapour–liquid equilibria, azeotropic data, excess enthalpies, activity coefficients at infinite dilution and solid–liquid equilibria for binary alcohol–ketone systems

    Microsoft Academic Search

    Rima Abbas; Jürgen Gmehling

    2008-01-01

    Isothermal vapour–liquid equilibria (VLE), solid–liquid equilibria and excess enthalpies have been measured for the systems cyclohexanone+cyclohexanol and 2-octanone+1-hexanol. Additionally in this paper binary azeotropic data at different pressures for 1-pentanol+2-heptanone and 1-hexanol+2-octanone have been determined with the help of a wire band column. Furthermore activity coefficients at infinite dilution for methanol, ethanol, 1-butanol and 1-propanol in 2-octanone at different temperatures

  13. Contributions of additional group interaction parameters through limiting activity coefficient measurements on aliphatic alcohols, aromatic hydrocarbons, ketones and an ester in tetrahydroxyethylethylenediamine and tetraethylene pentamine

    Microsoft Academic Search

    S. M. Ashraf; M. Ramakrishna; D. H. L. Prasad; M. Bhagwanth Rao

    1999-01-01

    Gas chromatographic method has been used to measure the limiting activity coefficient of some aliphatic alcohols (ethanol, 1-propanol, 1-butanol and 1-pentanol), aromatic hydrocarbons (benzene, toluene, ethylbenzene, o-xylene and p-xylene), ketones (acetone and methylisobutylketone), ethylacetate and chlorobenzene in tetrahydroxyethylethylenediamine (THEEDA) and tetraethylpentamine (TEPA). The measurements involving THEEDA have been used to derive UNIFAC group interaction parameters for seven new pairs, while

  14. A Monte Carlo study of absorbed dose distributions in both the vapor and liquid phases of water by intermediate energy electrons based on different condensed-history transport schemes

    NASA Astrophysics Data System (ADS)

    Bousis, C.; Emfietzoglou, D.; Hadjidoukas, P.; Nikjoo, H.

    2008-07-01

    Monte Carlo transport calculations of dose point kernels (DPKs) and depth dose profiles (DDPs) in both the vapor and liquid phases of water are presented for electrons with initial energy between 10 keV and 1 MeV. The results are obtained by the MC4 code using three different implementations of the condensed-history technique for inelastic collisions, namely the continuous slowing down approximation, the mixed-simulation with ?-ray transport and the addition of straggling distributions for soft collisions derived from accurate relativistic Born cross sections. In all schemes, elastic collisions are simulated individually based on single-scattering cross sections. Electron transport below 10 keV is performed in an event-by-event mode. Differences on inelastic interactions between the vapor and liquid phase are treated explicitly using our recently developed dielectric response function which is supplemented by relativistic corrections and the transverse contribution. On the whole, the interaction coefficients used agree to better than ~5% with NIST/ICRU values. It is shown that condensed phase effects in both DPKs and DDPs practically vanish above 100 keV. The effect of ?-rays, although decreases with energy, is sizeable leading to more diffused distributions, especially for DPKs. The addition of straggling for soft collisions is practically inconsequential above a few hundred keV. An extensive benchmarking with other condensed-history codes is provided.

  15. Magnetic properties of liquid-phase sintered CoFe?O? for application in magnetoelastic and magnetoelectric transducers.

    PubMed

    de Brito, Vera Lúcia Othéro; Cunha, Stéphanie Alá; Lemos, Leonardo Violim; Nunes, Cristina Bormio

    2012-01-01

    Cobalt ferrite is a ferrimagnetic magnetostrictive ceramic that has potential application in magnetoelastic and magnetoelectric transducers. In this work, CoFe(2)O(4) was obtained using a conventional ceramic method and Bi(2)O(3) was used as additive in order to obtain liquid-phase sintered samples. Bi(2)O(3) was added to the ferrite in amounts ranging from 0.25 mol% to 0.45 mol% and samples were sintered at 900 °C and 950 °C. It was observed the presence of Bi-containing particles in the microstructure of the sintered samples and the magnetostriction results indicated microstructural anisotropy. It was verified that it is possible to get dense cobalt ferrites, liquid-phase sintered, with relative densities higher than 90% and with magnetostriction values very close to samples sintered without additives. PMID:23112589

  16. Ground-state and finite-temperature properties of spin liquid phase in the J1-J2 honeycomb model

    NASA Astrophysics Data System (ADS)

    Yu, Xiang-Long; Liu, Da-Yong; Li, Peng; Zou, Liang-Jian

    2014-05-01

    In this paper we analyze the groundstate and finite-temperature properties of a frustrated Heisenberg J1-J2 model on a honeycomb lattice by employing the Schwinger boson technique. The phase diagram and spin gap as functions of J2/J1 are presented, showing that the exotic spin liquid phase lies in 0.21liquid phase for further experiments.

  17. Reaction equilibria in the synthesis of 2-methoxy-2-methylbutane and 2-ethoxy-2-methylbutane in the liquid phase

    Microsoft Academic Search

    Liisa K. Rihko; Juha A. Linnekoski; A. Outi I. Krause

    1994-01-01

    Tertiary ethers are used as octane-enhancing components in gasoline. Equilibrium constants for the liquid-phase synthesis of 2-methoxy-2-methylbutane (TAME) and 2-ethoxy-20methylbutane (TAEE) were measured in the temperature range 323-363 K. The equilibria were studied using the alcohol\\/alkene mixture in various mole ratios and the respective ether as a reagent in a batch reactor. A commercial cation exchange resin (Amberlyst 16) was

  18. Identification of monoacyl- and monoalkylglycerols by gas-liquid chromatography-mass spectrometry using polar siloxane liquid phases

    Microsoft Academic Search

    J. J. Myher; L. Marai; A. Kuksis

    A comparative study was made of the spectra ob- tained after gas-liquid chromatography-mass spectrometry of the trimethylsilyl ethers of 1- and 2-monoacyl- and monoalkyl- glycerols. The glycerol derivatives were resolved on the basis of positional substitution and the degree of unsaturation on Silar- 5CP (a cyanopropylphenylsiloxane) liquid phase, and the peaks were examined in a Varian MAT CH-5 single-focusing mass

  19. Extracellular polymeric substances enhanced mass transfer of polycyclic aromatic hydrocarbons in the two-liquid-phase system for biodegradation

    Microsoft Academic Search

    Yinping Zhang; Fang Wang; Xinglun Yang; Chenggang Gu; Fredrick Orori Kengara; Qing Hong; Zhengyong Lv; Xin Jiang

    2011-01-01

    The objective was to elucidate the role of extracellular polymeric substances (EPS) in biodegradation of polycyclic aromatic\\u000a hydrocarbons in two-liquid-phase system (TLPs). Therefore, biodegradation of phenanthrene (PHE) was conducted in a typical\\u000a TLPs—silicone oil–water—with PHE-degrading bacteria capable of producing EPS, Sphingobium sp. PHE3 and Micrococcus sp. PHE9. The results showed that the presence of both strains enhanced mass transfer of

  20. Vibrational analysis of small species in the liquid phase by a combined density functional theory and polarizable continuum method

    Microsoft Academic Search

    A. L. Magalhães; A. S. Soares Pinto

    2003-01-01

    The vibrational frequencies of small organic molecules and inorganic ions were predicted both in vacuum and in the liquid phase at the B3LYP\\/6-311G++(d,p) level of theory, within the harmonic approximation. The solvent effect was introduced as an electrostatic influence of the bulk by means of the integral equation formalism of the polarizable continuum model. The results show that the application

  1. Enhancement of metal–semiconductor barrier height with superthin silicon dioxide films deposited on gallium arsenide by liquid phase deposition

    Microsoft Academic Search

    C. J. Huang

    2001-01-01

    This study presents a method for surface passivation using silicon dioxide (SiO2). The proposed method has shown great effectiveness on metal–semiconductor barrier height enhancement. A high quality SiO2 layer is developed via liquid phase deposition, a method which naturally leaves a doping-level fluorine residue in the SiO2. The addition of fluorine to enhance the Schottky barrier height (SBH) is first

  2. Enhancement of metal-semiconductor barrier height with superthin silicon dioxide films deposited on gallium arsenide by liquid phase deposition

    Microsoft Academic Search

    C. J. Huang

    2001-01-01

    This study presents a method for surface passivation using silicon dioxide (SiO2). The proposed method has shown great effectiveness on metal-semiconductor barrier height enhancement. A high quality SiO2 layer is developed via liquid phase deposition, a method which naturally leaves a doping-level fluorine residue in the SiO2. The addition of fluorine to enhance the Schottky barrier height (SBH) is first

  3. Synthesis of dimethyl ether and alternative fuels in the liquid phase from coal-derived synthesis gas

    Microsoft Academic Search

    1993-01-01

    As part of the DOE-sponsored contract Synthesis of Dimethyl Ether and Alternative Fuels in the Liquid Phase from Coal-Derived Syngas'' experimental evaluations of the one-step synthesis of alternative fuels were carried out. The objective of this work was to develop novel processes for converting coal-derived syngas to fuels or fuel additives. Building on a technology base acquired during the development

  4. Antireflection and SiO2 Surface Passivation by Liquid-Phase Chemistry for Efficient Black Silicon Solar Cells: Preprint

    Microsoft Academic Search

    H. C. Yuan; J. Oh; Y. Zhang; O. A. Kuznetsov; D. J. Flood; H. M. Branz

    2012-01-01

    We report solar cells with both black Si antireflection and SiO2 surface passivation provided by inexpensive liquid-phase chemistry, rather than by conventional vacuum-based techniques. Preliminary cell efficiency has reached 16.4%. Nanoporous black Si antireflection on crystalline Si by aqueous etching promises low surface reflection for high photon utilization, together with lower manufacturing cost compared to vacuum-based antireflection coating. Ag-nanoparticle-assisted black

  5. Influence of ultrasound power on the alkylation of phenylacetonitrile under solid-liquid phase transfer catalysis conditions.

    PubMed

    Guilet, R; Berlan, J; Louisnard, O; Schwartzentruber, J

    1998-03-01

    The influence of ultrasound power on the C-alkylation of phenylacetonitrile by ethyl bromide was studied under solid-liquid phase transfer catalysis in the presence of potassium hydroxide and tetrabutylammonium hydrogenosulfate. Experimental results are reported on the influence of the ultrasonic power on the yields. The optimum efficiency of ultrasounds is determined and the way in which ultrasound power may affect the yields is discussed. PMID:11270331

  6. Soot and liquid-phase fuel distributions in a newly designed optically accessible D.I. diesel engine

    SciTech Connect

    Dec, J.E. [Sandia National Labs., Livermore, CA (United States); Espey, C. [Pennsylvania State Univ., University Park, PA (United States)

    1993-10-01

    Two-dimensional (2-D) laser-sheet imaging has been used to examine the soot and liquid-phase fuel distributions in a newly designed, optically accessible, direct-injection Diesel engine of the heavy-duty size class. The design of this engine preserves the intake port geometry and basic dimensions of a Cummins N-series production engine. It also includes several unique features to provide considerable optical access. Liquid-phase fuel and soot distribution studies were conducted at a medium speed (1,200 rpm) using a Cummins closed-nozzle fuel injector. The scattering was used to obtain planar images of the liquid-phase fuel distribution. These images show that the leading edge of the liquid-phase portion of the fuel jet reaches a maximum length of 24 mm, which is about half the combustion bowl radius for this engine. Beyond this point virtually all the fuel has vaporized. Soot distribution measurements were made at a high load condition using three imaging diagnostics: natural flame luminosity, 2-D laser-induced incandescence, and 2-D elastic scattering. This investigation showed that the soot distribution in the combusting fuel jet develops through three stages. First, just after the onset of luminous combustion, soot particles are small and nearly uniformly distributed throughout the luminous region of the fuel jet. Second, after about 2 crank angle degrees a pattern develops of a higher soot concentration of larger sized particles in the head vortex region of the jet and a lower soot concentration of smaller sized particles upstream toward the injector. Third, after fuel injection ends, both the soot concentration and soot particle size increase rapidly in the upstream portion of the fuel jet.

  7. The Effects of Composition and Microstructure on the Thermal Conductivity of Liquid-Phase-Sintered W-Cu

    Microsoft Academic Search

    John L. Johnson; Seong Jin Park; Young-Sam Kwon; Randall M. German

    2010-01-01

    Liquid-phase sintering of high-purity, submicron, co-reduced W-15Cu powders at temperatures of 1463 to 1623 K (1190 to 1350 °C) produces W grain sizes ranging from 0.6 to 1.2 mum while maintaining less than 2 pct porosity. Measured thermal conductivities of 185 to 221 W\\/(m·K) are related to the grain size and contiguity, which ranged from 0.51 to 0.62. The effects

  8. Interfacial microstructure of partial transient liquid phase bonded Si 3N 4-to-Inconel 718 joints

    Microsoft Academic Search

    Jae Joong Kim; Jin-Woo Park; Thomas W. Eagar

    2003-01-01

    This work presents transmission electron microscopy (TEM) analysis of the interfacial microstructure in Si3N4-to-Inconel 718 joints with Ni interlayers produced by partial transient liquid phase bonding (PTLPB). Ti and Cu microfoils have been inserted between Si3N4 and the Ni interlayer and joining has been performed at lower temperatures than previous PTLPBs of Si3N4 with the same insert metals. The TEM

  9. Interphase boundary precipitation in liquid phase sintered W-Ni-Fe and W-Ni-Cu alloys

    Microsoft Academic Search

    1984-01-01

    The microstructure of liquid-phase sintered, tungsten-based heavy alloys comprises a continuous network of spheroidal tungsten\\u000a single crystals embedded in a ductile, fcc matrix phase, and the integrity of the tungsten-matrix interphase boundaries established\\u000a during processing is of major importance in determining the resultant mechanical properties. A serious potential source of\\u000a embrittlement in these systems involves the precipitation of a brittle

  10. A study of the transient liquid phase bonding process applied to a Ag\\/Cu\\/Ag sandwich joint

    Microsoft Academic Search

    Isaac Tuah-Poku; M. Dollar; T. B. Massalski

    1988-01-01

    Transient liquid phase (TLP) bonding is a process currently used for joining heat resistant alloys, for example nickel- and\\u000a cobalt-based superalloys. It involves the formation of a liquid layer between two adjoining pieces and the formation of a\\u000a solid bond as the liquid disappears during annealing at a suitable constant temperature. In the present study, a model Ag\\/Cu\\/Ag\\u000a sandwich joint

  11. Microstructural study of transient liquid phase bonded DD98 and K465 superalloys at high temperature

    SciTech Connect

    Liu Jide, E-mail: jdliu@imr.ac.cn; Jin Tao; Zhao Nairen; Wang Zhihui; Sun Xiaofeng; Guan Hengrong; Hu Zhuangqi

    2011-05-15

    Microstructure of a transient liquid phase (TLP) bonded joint between single crystal DD98 and polycrystalline K465 superalloys was investigated by scanning electron microscopy, transmission electron microscopy and X-ray diffraction techniques. After bonding at 1190 deg. C for 2 h, many phases formed in the centerline of the bonding zone due to an incompletely solidified liquid interlayer. There are script-like, tree-like and blocky compounds besides solid solution {gamma} phase in this region. The script-like phase is CrB boride that is rich in Cr, the tree-like compound rich in Ni is M{sub 23}B{sub 6} with FCC structure, and the blocky phase enriched in Ti, Ta, and Nb, is MC carbide that resulted from the interdiffusion of C atoms between dissimilar base metals. After TLP bonding, many blocky and fine M{sub 6}C particles rich in Cr and W appeared in the diffusion zone of the K465 side. A number of blocky and platelet M{sub 3}B{sub 2} borides rich in W, Cr and Mo precipitated in the diffusion zone of the DD98 side. - Research Highlights: {yields} DD98 and K465 alloy was TLP bonded. {yields} The microstructure changes of different parts were studied. {yields} CrB, M{sub 23}B{sub 6} and MC formed in the bonding zone. {yields} M{sub 6}C appeared in diffusion zone of K465 side and M{sub 3}B{sub 2} existed in diffusion zone of DD98 side.

  12. Liquid-phase processing of fast pyrolysis bio-oil using platinum/HZSM-5 catalyst

    NASA Astrophysics Data System (ADS)

    Santos, Bjorn Sanchez

    Recent developments in converting biomass to bio-chemicals and liquid fuels provide a promising sight to an emerging biofuels industry. Biomass can be converted to energy via thermochemical and biochemical pathways. Thermal degradation processes include liquefaction, gasification, and pyrolysis. Among these biomass technologies, pyrolysis (i.e. a thermochemical conversion process of any organic material in the absence of oxygen) has gained more attention because of its simplicity in design, construction and operation. This research study focuses on comparative assessment of two types of pyrolysis processes and catalytic upgrading of bio-oil for production of transportation fuel intermediates. Slow and fast pyrolysis processes were compared for their respective product yields and properties. Slow pyrolysis bio-oil displayed fossil fuel-like properties, although low yields limit the process making it uneconomically feasible. Fast pyrolysis, on the other hand, show high yields but produces relatively less quality bio-oil. Catalytic transformation of the high-boiling fraction (HBF) of the crude bio-oil from fast pyrolysis was therefore evaluated by performing liquid-phase reactions at moderate temperatures using Pt/HZSM-5 catalyst. High yields of upgraded bio-oils along with improved heating values and reduced oxygen contents were obtained at a reaction temperature of 200°C and ethanol/HBF ratio of 3:1. Better quality, however, was observed at 240 °C even though reaction temperature has no significant effect on coke deposition. The addition of ethanol in the feed has greatly attenuated coke deposition in the catalyst. Major reactions observed are esterification, catalytic cracking, and reforming. Overall mass and energy balances in the conversion of energy sorghum biomass to produce a liquid fuel intermediate obtained sixteen percent (16 wt.%) of the biomass ending up as liquid fuel intermediate, while containing 26% of its initial energy.

  13. Growth of (11n) oriented BCSCO films by liquid phase epitaxial method

    SciTech Connect

    Raina, K.K.; Pandey, R.K. [Center for Electronic Materials, Devices and Systems, Department of Electrical Engineering, Texas AM University, College Station, Texas 77843-3253 (United States)

    1997-03-01

    Films of BCSCO superconductor of the Bi{sub 2}CaSr{sub 2}Cu{sub 2}O{sub x} composition have been grown by the liquid phase epitaxy method (LPE) using a partially closed growth chamber. The films were grown on (110) NdGaO{sub 3} substrates by slow cooling under optimized conditions below the peritectic melting point (885{degree}C) of Bi{sub 2}CaSr{sub 2}Cu{sub 2}O{sub 8}. Optimization of parameters, such as seed rotation, soak of initial growth temperature and growth period results in the formation of the 2122 phase of BCSCO. XRD measurements show that the films grown on (110) NdGaO{sub 3} have a preferred (11n)-orientation. The best values of zero resistance transition (T{sub c0}) and critical current density ( J{sub c}) obtained for films grown on (110) NdGaO{sub 3} substrates are 87 K and 5.7{times}10{sup 4} A/cm{sup 2} (at 20 K), respectively. The films grown at rotation rates of less than 30 and more than 80 rpm are observed to be associated with a sub-phase in the Bi{sub 2}CaSr{sub 2}Cu{sub 2}O{sub 8} system. Electron microprobe analysis indicates the composition of this sub-phase to be Bi{sub 0.07}Ca{sub 0.93}Sr{sub 2}Cu{sub 5}O{sub 8}. Higher growth temperatures ({gt}860{degree}C) also encourage the formation of this phase. {copyright} {ital 1997 Materials Research Society.}

  14. Novel Approach to Space-survivable Polyimides: Liquid Phase Deposition of Titania Coating on Kapton

    NASA Astrophysics Data System (ADS)

    Gouzman, Irina; Gershevitz, Olga; Grossman, Eitan; Eliaz, Noam; Sukenik, Chaim N.

    2009-01-01

    Polyimides are widely used as spacecraft external surfaces materials. They are exposed to atomic oxygen (AO), which is the main constituent of a residual atmosphere at low Earth orbit (LEO) and should be protected from the space harsh environment. This work presents an innovative approach to applying a protective coating on Kapton polyimide using liquid-phase deposition (LPD) and shows its effectiveness in reduction of AO-induced surface erosion. Titania coatings, 100 nm thick, were deposited on Kapton films by LPD using an aqueous solution of a metal-fluoride complex and boric acid at near ambient conditions. Adherent, crack-free, coatings have been obtained by optimization of the deposition conditions, the substrate surface pre-treatment procedure and post-deposition drying. Characterization of the oxide coating included Atomic Force Microscopy (AFM) in tapping and nano-indentation modes, Environmental Scanning Electron Microscopy (ESEM), and X-ray Photoelectron Spectroscopy (XPS). The durability of the titania coating under AO attack was studied using a RF plasma based facility. Surface erosion was measured both gravimetrically and by in situ Quartz Crystal Microbalance (QCM) measurements of mass loss. A dramatic reduction in the erosion of titania-coated Kapton relative to uncoated Kapton was observed: the erosion yield was as low as 2% of that of uncoated Kapton after exposure to 4×1020 O-atoms?cm?2 of LEO equivalent AO fluence. In addition, the surface hardness of coated Kapton was improved both in the as-deposited titania coatings and in the AO-exposed titania films.

  15. Transient-liquid-phase (TLP) bonding of aluminum trioxide using niobium-based multilayer interlayers

    NASA Astrophysics Data System (ADS)

    Hong, Sung Moo

    Transient-liquid-phase (TLP) bonding was used to join high-strength, high-purity Al2O3 ceramic. This method uses a multilayer interlayer (B/A/B sandwich structure), which forms thin transient-liquid layers between the Al2O3 and the refractory core layer (A), then isothermally solidifies through a diffusive mechanism. The presence of thin liquid layers allow interfacial gaps and voids to be filled, while allowing bonding times comparable to those used for conventional brazing. It was shown that TLP bonding produces high-strength joints with re-melt temperatures that are significantly higher than the bonding temperatures used. This study explores the interrelationships between the processing conditions, fracture strengths of the joints, wetting behavior of the TLP, and the diffusion/isothermal solidification kinetics. In particular, when Ni/Nb/Ni interlayers were utilized, four-point bend tests revealed that the fracture strengths of the joints matched those of the monolithic Al2O3, even after a 5-min holding time at 1400°C, the bonding temperature. The resulting interlayer consists of >99% Nb, which has a melting point >2000°C. Sessile-drop wetting experiments revealed that the Ni-Nb liquid alloy formed during bonding exhibits relatively low contact angles (?90°) on Al2O3, which enables the formation of nearly flaw-free interfaces. An analytical diffusion calculation model was also used to describe the isothermal-solidification and homogenization kinetics, and will be used in future studies to aid new interlayer designs.

  16. Molecular Competition of C 7 and C 9 n-Alkanes in Vapor and Liquid-Phase Hydroconversion over Bifunctional Pt–USY Zeolite Catalysts

    Microsoft Academic Search

    Joeri F. M. Denayer; Bruno De Jonckheere; Myriam Hloch; Guy B. Marin; Gina Vanbutsele; Johan A. Martens; Gino V. Baron

    2002-01-01

    Molecular competition effects in the hydroconversion of an equimolar heptane\\/nonane mixture were studied in liquid-phase reaction conditions in a fixed-bed reactor filled with a Pt–ultrastable-Y (USY) catalyst. Liquid-phase conditions were attained by feeding the hydrocarbon mixture with hydrogen dissolved in it at 100 bar and 230°C. Comparative vapor-phase experiments were run at 230°C, a pressure of 4.5 bar, and a

  17. Co(II), Mn(II), and Cr(III) iminodiacetate complexes heterogenized on silica gel in the liquid-phase oxidation of cyclohexene

    SciTech Connect

    Berentsveig, V.V.; Barinova, T.V.; Lisichkin, G.V.; Nga, C.B.

    1985-06-01

    A study was carried out on the catalytic properties of Co(II), Mn(II), and Cr(III) iminodiacetate complexes heterogenized on silica gel. The liquid-phase oxidation of cyclohexene in the presence of these catalysts proceeds mainly by a heterogeneous-homogeneous radical chain methanism. Variation in the selectivity of this liquid-phase reaction is possible by changing the nature of the transition metal ion.

  18. Liquid-phase compositions from vapor-phase analyses: 3, Reanalysis of HF vapor-densities and of UFâ-HF liquid-vapor equilibria

    Microsoft Academic Search

    W. Jr. Davis; H. D. Cochran

    1986-01-01

    Currently, liquid-phase samples from uranium hexafluoride (UFâ) cylinders are used by all US Department of Energy enrichment facilities for determining the chemical content of cylinders - a requisite in the control and accountability of nuclear materials. Previously published reports note the economic incentive to use vapor-phase sampling for volatile impurities if the liquid-phase composition can be determined from analysis of

  19. Transient liquid phase bonding of a third generation gamma-titanium aluminum alloy: Gamma Met PX

    NASA Astrophysics Data System (ADS)

    Butts, Daniel A.

    The research work presented here discusses transient liquid phase (TLP) bonding of a current (i.e. third) generation gamma-TiAl alloy known as Gamma Met PX (GMPX). Effective implementation of GMPX in service is likely to require fabrication of complicated geometries for which a high performance metallurgical joining technique must be developed. Although a number of joining processes have been investigated, all have significant disadvantages that limit their ability to achieve sound joints. TLP bonding has proved to be a successful method of producing joints with microstructures and compositions similar to that of the bulk substrates. Hence, bonds with parent-like mechanical and oxidation properties are possible. The interlayer and bonding conditions employed for joining of GMPX were based on successful wide-gap TLP joining trials of an earlier generation cast gamma-TiAl alloy with a composition of Ti-48Al-2Cr-2Nb in atomic percent (abbreviated here to 48-2-2). A composite interlayer consisting of a 6:1 weight ratio (7 vol.% copper) of gas atomized 48-2-2 powders (-270 mesh) and pure copper powders (-325 mesh) was employed. When applied to GMPX, these interlayer ratio and bonding conditions produced undesirable microstructures and poor mechanical performance in as-bonded joints. Thus, modifications to the joining technique were required. Initially these modifications were based purely on empirical and phenomenological studies, however, detailed mechanistic studies of the underlying joining mechanisms were conducted to aid in selecting these modifications. Mechanisms such as diffusion, solubility and wettability of copper in/on GMPX and 48-2-2 bulk substrates were investigated and compared. A difference in solubility of copper in GMPX and 48-2-2 bulk substrates was attributed to (at least in part) to the observed differences in GMPX and 48-2-2 bonds. The copper solubility, at the bonding temperature, in the 48-2-2 and GMPX alloys was determined to be ˜2 at.% and ˜1 at.% respectively. To compensate for the lower copper solubility in GMPX, the copper content of the composite interlayer employed in GMPX bonds was reduced was reduced from an initial ratio of 6:1 to 50:1. GMPX TLP bonds employing a 50:1 weight ratio (1 vol.% copper) of Gamma Met plus copper powders produced joints with a microstructure and room temperature mechanical properties somewhat comparable to the bulk material after bonding. A subsequent post-bond heat treatment produced a bond-line with a microstructure and room temperature mechanical properties similar to those of the bulk material subjected to the same thermal cycle.

  20. Liquid-phase micro-extraction techniques in pesticide residue analysis.

    PubMed

    Lambropoulou, Dimitra A; Albanis, Triantafyllos A

    2007-03-10

    Modern trends in analytical chemistry are towards the simplification and miniaturization of sample preparation, as well as the minimization of organic solvent used. In view of this aspect, several novel micro-extraction techniques are being developed in order to reduce the analysis step, increase the sample throughput and to improve the quality and the sensitivity of analytical methods. One of the emerging techniques in this area is liquid-phase micro-extraction (LPME). It is a miniaturized implementation of conventional liquid/liquid extraction (LLE) in which only microliters of solvents are used instead of several hundred milliliters in LLE. It is quick, inexpensive and can be automated. In the last few years, LPME has been combined with liquid chromatography (LC) and capillary electrophoresis (CE), besides the generally used coupling to gas chromatography (GC), and has been applied to various matrices, including biological, environmental, and food samples. This work is aimed at providing an overview of the major developments of LPME, coupled with chromatography and CE, as reported in the literature. The paper will focus on the application of the technique to different matrices and the aim is to reveal the panorama of opportunities and to try to indicate the potential of LPME in pesticide analysis. A critical review of the first applications to pesticide analyses is presented in the main part of the manuscript. The optimization of LPME as well as advantages and disadvantages are discussed. It is concluded that, because of its high pre-concentration factor, LPME can be introduced with benefit into water analysis for several pesticide groups. In particular, the application of LPME to non-polar pesticides in environmental analysis appears to be promising. However, similar to other micro-extraction techniques, such as solid phase micro-extraction (SPME), serious limitations still remain when analyzing semi-solid and solid environmental, food or biological matrices and/or highly polar compounds. Thus, other pre-concentration techniques may be a good alternative if an analytical problem cannot be sufficiently dealt with LPME. PMID:17161462

  1. Hollow fiber-liquid-phase microextraction of fungicides from orange juices.

    PubMed

    Barahona, Francisco; Gjelstad, Astrid; Pedersen-Bjergaard, Stig; Rasmussen, Knut Einar

    2010-03-26

    Liquid-phase microextraction (LPME) based on polypropylene hollow fibers was evaluated for the extraction of the post-harvest fungicides thiabendazole (TBZ), carbendazim (CBZ) and imazalil (IMZ) from orange juices. Direct LPME was performed without any sample pretreatment prior to the extraction, using a simple home-built equipment. A volume of 500 microL of 840 mM NaOH was added to 3 mL of orange juice in order to compensate the acidity of the samples and to adjust pH into the alkaline region. Analytes were extracted in their neutral state through a supported liquid membrane (SLM) of 2-octanone into 20 microL of a stagnant aqueous solution of 10 mM HCl inside the lumen of the hollow fiber. Subsequently, the acceptor solution was directly subjected to analysis. Capillary electrophoresis (CE) was used during the optimization of the extraction procedure. Working under the optimized extraction conditions, LPME effectively extracted the analytes from different orange juices, regardless of different pH or solid material (pulp) present in the sample, with recoveries that ranged between 17.0 and 33.7%. The analytical performance of the method was evaluated by liquid chromatography coupled with mass spectrometry (LC/MS). This technique provided better sensitivity than CE and permitted the detection below the microg L(-1) level. The relative standard deviations of the recoveries (RSDs) ranged between 3.4 and 10.6%, which are acceptable values for a manual microextraction technique without any previous sample treatment, using a home-built equipment and working under non-equilibrium conditions (30 min extraction). Linearity was obtained in the range 0.1-10.0 microg L(-1), with r=0.999 and 0.998 for TBZ and IMZ, respectively. Limits of detection were below 0.1 microg L(-1) and are consistent with the maximum residue levels permitted for pesticides in drinking water, which is the most restrictive regulation applicable for these kinds of samples. It has been demonstrated the suitability of three-phase LPME for the extraction of pesticides from citrus juices, suppressing any pretreatment step such as filtration or removal of the solid material from the sample, that may potentially involve a loss of analyte. PMID:20181342

  2. Liquid phase sintered composite solders for next generation thermal interface applications

    NASA Astrophysics Data System (ADS)

    Liu, Jia

    It is undeniable that electronics are becoming increasingly powerful and that there is continual effort towards miniaturization of these devices and thus increasing heat generation requires a new paradigm in thermal interface materials (TIM) design. This work was aimed at optimizing the processing parameters and characterizing the performance of Cu-In composite solders produced by liquid phase sintering (LPS). These composites comprise a high-melting phase (HMP) such as Cu embedded in a matrix of a low-melting phase (LMP) such as In. Copper contributes to high thermal and electrical conductivity of composites, whereas the soft In matrix helps maintain high shear compliance. This combination of high electrical/thermal conductivities and high shear compliance makes these solders suitable for a range of next-generation thermal interface material (TIM) and interconnect (IC) applications. After considering a range of compositions, a solder with 60 volume percent In was found to possess the requisite combination of high compliance and high conductivity. During the study, interfacial engineering was introduced to slow down the reaction between Cu and In, and hence further improve the performance of composite solders. A dual interfacial layer consisting of Al 2O3 and Au was used to mitigate the reaction between Cu and In. A 1 nm Al2O3 layer was used as a diffusion barrier to prohibit the inter-diffusion between Cu and In, while a 20 nm Au layer was coated on top of the ceramic Al2O3 for wetting enhancement. The dual layer increased the thermal conductivity of the solder by a factor of ˜2 while reducing the yield strength to make the solder more compliant. The effects of particle size, shape and volume fraction was also studied, and a simple model was utilized to explain the trends in the mechanical and the thermal properties. The optimized Cu-In composite solders were further used to study the performance of solder joints. Mechanical properties under shear and joint thermal resistance were measured as a function of joint thickness, thermal excursion history, and different inter-layers between solder and Cu. Minimizing interfacial contact-resistance is desired, especially when the joint thickness becomes sub-millimeter, and hence role of inter-layer on the contact-resistance was studied.

  3. Effect of pressure profile on evaluation of volumetric mass transfer coefficient in k L a bioreactors

    Microsoft Academic Search

    Karel Petera; Pavel Ditl

    2000-01-01

    The volumetric mass transfer coefficient kLa is a very important parameter that plays an important role in bioreactor design. Numerous authors have reported that the use of simple models not taking into account the dispersion effects in the gas and\\/or liquid phase may cause a large error in kLa estimation. We have analysed the effect of another factor on kLa

  4. Systematic and practical solvent system selection strategy based on the nonrandom two-liquid segment activity coefficient model for real-life counter-current chromatography separation.

    PubMed

    Ren, Da-Bing; Yi, Lun-Zhao; Qin, Yan-Hua; Yun, Yong-Huan; Deng, Bai-Chuan; Lu, Hong-Mei; Chen, Xiao-Qing; Liang, Yi-Zeng

    2015-05-01

    Solvent system selection is the first step toward a successful counter-current chromatography (CCC) separation. This paper introduces a systematic and practical solvent system selection strategy based on the nonrandom two-liquid segment activity coefficient (NRTL-SAC) model, which is efficient in predicting the solute partition coefficient. Firstly, the application of the NRTL-SAC method was extended to the ethyl acetate/n-butanol/water and chloroform/methanol/water solvent system families. Moreover, the versatility and predictive capability of the NRTL-SAC method were investigated. The results indicate that the solute molecular parameters identified from hexane/ethyl acetate/methanol/water solvent system family are capable of predicting a large number of partition coefficients in several other different solvent system families. The NRTL-SAC strategy was further validated by successfully separating five components from Salvia plebeian R.Br. We therefore propose that NRTL-SAC is a promising high throughput method for rapid solvent system selection and highly adaptable to screen suitable solvent system for real-life CCC separation. PMID:25818557

  5. Determination of excess Gibbs free energy by the single-charging-integral approach. 2. Infinite dilution activity coefficients and related quantities

    SciTech Connect

    Chialvo, A.A. (Princeton Univ., NJ (United States))

    1991-08-22

    The recently proposed single-charging-integral method for the accurate determination of thermodynamic excess properties of mixtures via isobaric-isothermal molecular dynamics, is applied to the calculation of the infinite dilution activity coefficients, the ratio of pure component fugacities, and the ratio of Henry's constants of binary Lennard-Jones mixtures. An alternative coupling-parameter technique for the direct calculation of the infinite dilution quantities is also presented. Both these methods allow the calculation of individual contributions of any source of nonideality to the infinite dilution quantities, involve well-behaved charging integrands, and do not require the knowledge of pure component properties.

  6. Growth of Pb 1- xSn xTe ( x?0.12) epitaxial layers by temperature difference under controlled vapor pressure liquid-phase epitaxy

    NASA Astrophysics Data System (ADS)

    Nugraha, .; Tamura, Wataru; Itoh, Osamu; Suto, Ken; Nishizawa, Jun-ichi

    2000-10-01

    Pb 1- xSn xTe ( x?0.12) liquid-phase epitaxial layers have been grown by the temperature difference method under controlled vapor pressure (TDM-CVP) using Pb solvents on PbTe substrates at temperatures 490°C and 600°C. The grown layers are usually n-type, and the optimum Te vapor pressure where the carrier concentration becomes minimum is 3.1×10 -3> PTe>1.4×10 -3 Torr for Tg=600°C, and 3.1×10-5 >P Te>1.4×10-5 Torr for Tg=490°C. The activation energy of the optimum Te vapor pressure for Pb 1- xSn xTe ( x?0.12) is 2.38 eV, which is larger than the activation energy for PbTe, 2.12 eV. Two different types of etch pits are observed on Pb 1- xSn xTe ( x?0.12) layers. The density of the smaller size etch pits tends to become minimum at the optimum Te vapor pressure, while the larger size etch pits are dominantly observed at the vapor pressure region above the optimum vapor pressure. This tendency and lower electron mobility suggest defect aggregation taking place above the optimum vapor pressure.

  7. Liquid-phase methanation/shift process development. Final technical report, September 1, 1980-November 30, 1981

    SciTech Connect

    Not Available

    1982-05-12

    This final technical report covers the work performed between September 1, 1980 and November 30, 1981 relating to Chem Systems' Liquid Phase Methanation/Shift Process. A total of 44 runs were completed covering testing of five commercially available catalysts at 900/sup 0/F, 1000 psig and 10,000 h/sup -1/ VHSV. The shifted methanation feed gas consisted of 63% H/sub 2/, 19% CO, 2% CO/sub 2/ and 16% CH/sub 4/. To determine the effects of steam, twenty of the scans had 15% steam injected into the feed gas. Each test ran for 100, 300, 600 or 1200 hours with continuous effluent sampling and temperature profile monitoring. At each of the termination points, a catalyst sample was taken from the hot spot section of the bed for analysis. Carbon was deposited on the catalyst under the methanation conditions studied. The rate of carbon deposition was primarily a function of catalyst properties and not of the thermodynamics of the methanation reaction system. In spite of heavy carbon deposition, the catalytic behavior for these systems generally remains unaffected. Physical plugging of the catalyst bed is the limiting condition of the process and not catalyst deactivation. In this respect, a controlled oxidation of the carbon deposits is a viable method of extending catalyst life. The hydrodynamics and design of a cold-flow test unit for a three-phase, liquid-fluidized bed for Liquid Phase Methanation/Shift was evaluated. The cold-flow unit process design, equipment take-off lists, consruction cost and timing schedule are included. As a second potential application, the unit was designed for hydrodynamic studies of a liquid-entrained system for Liquid Phase Methanation/Shift.

  8. 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-fidelity codes for multi-phase flows.

  9. Sulfur mass-independent fractionation in liquid phase chemistry: UV photolysis of phenacylphenylsulfone as a case study

    NASA Astrophysics Data System (ADS)

    Kopf, Sebastian; Ono, Shuhei

    2012-05-01

    The sulfur isotope mass-independent fractionation (S-MIF) represents a distinct geochemical signature commonly observed in Archean rocks. Although S-MIF is generally thought to be exclusive to gas phase chemistry, several studies have suggested that liquid phase or heterogeneous chemistry may also produce S-MIF signatures. This study investigates the potential contribution of the poorly explored mass-independent effects from liquid phase sulfur chemistry. Our investigation focused on laboratory experiments of the UV photolysis of phenacylphenylsulfone as a model system. This system was chosen due to previous measurements of ?33S (not ?36S) by a low precision SO2 method indicating the occurrence of anomalous fractionation in 33S. The photolysis of PPS in micellar solution produced MIF of 33S in residual PPS ranging from depletion by -2.1‰ to enrichment by 6.4‰, with small mass-dependent fractionation of ?34S up to 2.1‰. While this magnitude of 33S anomaly is comparable to the range of values observed in Archean rocks, no anomaly in 36S was detected for the 32S-34S-36S system beyond analytical precision (0.19‰). These results confirm the anomalous fractionation to be caused most likely by magnetic isotope effects (MIE), affecting only the nuclear spin possessing 33S among the four stable isotopes of sulfur. The observed initial depletion of 33S in the reactant PPS was unexpected and suggests changing contributions of at least two spin-selective processes. The results of this study demonstrate that liquid phase processes, such as the photolysis of certain organic sulfur compounds, can produce anomalous 33S abundance.

  10. Characterization of transparent conducting p-type nickel oxide films grown by liquid phase deposition on glass

    NASA Astrophysics Data System (ADS)

    Lee, Ming-Kwei; Lai, Yen-Ting

    2013-02-01

    Transparent conducting nickel oxide (NiO) films were prepared by liquid phase deposition on glass. Saturated NiF2 and boric acid solutions were used as precursors. There was a growth delay time of 5 h and the growth rate was 34.3 nm per hour in the growth region. After annealing at 400 °C in air, the resistivity was improved from 4.85 × 103 ? cm to 7.5 × 10-1 ? cm, and the transmittance decreased from 91.85% to 66.49% at a wavelength of 550 nm, respectively.

  11. Liquid-phase polymer-based retention and coupled electrocatalytic oxidation to remove Arsenic in the presence of competitive species

    Microsoft Academic Search

    María del Carmen Aguirre; Bernabé L. Rivas; Carlos Peña; Luis Basaez

    The goal was to remove arsenate species in the presence of competitive anions by coupling of liquid-phase polymer-based retention,\\u000a LPR, a procedure based on the selective As(V) adsorption properties of cationic water-soluble polymers, with an electro-catalytic\\u000a oxidation process (EO) of As(III) into its more easily removable As(V). The electro-catalytic oxidation of As(III) to As(V)\\u000a was performed with an organic supporting

  12. Direct screening of ground water samples for fuel oxygenates by headspace liquid phase microextraction–gas chromatography

    Microsoft Academic Search

    Massoud Kaykhaii; Mohammad Reza Mirbaloochzahi

    2008-01-01

    The applicability of the headspace liquid phase microextraction and gas chromatography (HS-LPME\\/GC) for the expeditious and\\u000a reliable screening of 68 well water samples for selected fuel oxygenates compounds, viz. methyl tertiary-butyl ether (MTBE),\\u000a tertiary-amyl methyl ether (TAME), ethyl tertiary-butyl ether (ETBE) and n-butyl ethyl ether (n-BEE) has been evaluated. The method used 3 ?l of 1:1 benzyl alcohol\\/1-octanol as extraction solvent,

  13. Liquid-phase plasma synthesis of silicon quantum dots embedded in carbon matrix for lithium battery anodes

    SciTech Connect

    Wei, Ying [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou (China); College of Chemistry and Chemical Engineering, Bohai University, Jinzhou 121000 (China); Yu, Hang; Li, Haitao; Ming, Hai; Pan, Keming; Huang, Hui [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou (China); Liu, Yang, E-mail: yangl@suda.edu.cn [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou (China); Kang, Zhenhui, E-mail: zhkang@suda.edu.cn [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou (China)

    2013-10-15

    Graphical abstract: - Highlights: • Silicon quantum dots embedded in carbon matrix (SiQDs/C) were fabricated. • SiQDs/C exhibits excellent battery performance as anode materials with high specific capacity. • The good performance was attributed to the marriage of small sized SiQDs and carbon. - Abstract: Silicon quantum dots embedded in carbon matrix (SiQDs/C) nanocomposites were prepared by a novel liquid-phase plasma assisted synthetic process. The SiQDs/C nanocomposites were demonstrated to show high specific capacity, good cycling life and high coulmbic efficiency as anode materials for lithium-ion battery.

  14. Buoyant thermocapillary flow with nonuniform supra-heating. I - Liquid-phase behavior. II - Two-phase behavior

    NASA Astrophysics Data System (ADS)

    Schiller, David N.; Sirignano, William A.

    1992-03-01

    The present computational study of transient heat transfer and fluid flow in a circular pool of n-decane which is undergoing central radiative heating from above gives attention to the volumetric absorption of the radiation incident on the pool surface. The first part of this study notes that buoyancy influences the number and recirculation rates of the subsurface vortices by stabilizing hot subsurface fluid above the colder core fluid; this affects the liquid surface temperature profile and in turn governs the velocity profile that is due to thermocapillarity. In the second part, the effects of gas-liquid phase coupling, variable density and thermophysical properties, and vaporization are considered.

  15. Buoyant thermocapillary flow with nonuniform supra-heating. I - Liquid-phase behavior. II - Two-phase behavior

    NASA Technical Reports Server (NTRS)

    Schiller, David N.; Sirignano, William A.

    1992-01-01

    The present computational study of transient heat transfer and fluid flow in a circular pool of n-decane which is undergoing central radiative heating from above gives attention to the volumetric absorption of the radiation incident on the pool surface. The first part of this study notes that buoyancy influences the number and recirculation rates of the subsurface vortices by stabilizing hot subsurface fluid above the colder core fluid; this affects the liquid surface temperature profile and in turn governs the velocity profile that is due to thermocapillarity. In the second part, the effects of gas-liquid phase coupling, variable density and thermophysical properties, and vaporization are considered.

  16. The Effects of Composition and Microstructure on the Thermal Conductivity of Liquid-Phase-Sintered W-Cu

    Microsoft Academic Search

    John L. Johnson; Seong Jin Park; Young-Sam Kwon; Randall M. German

    2010-01-01

    Liquid-phase sintering of high-purity, submicron, co-reduced W-15Cu powders at temperatures of 1463 to 1623 K (1190 to 1350 °C)\\u000a produces W grain sizes ranging from 0.6 to 1.2 ?m while maintaining less than 2 pct porosity. Measured thermal conductivities of 185 to 221 W\\/(m·K) are related to the grain\\u000a size and contiguity, which ranged from 0.51 to 0.62. The effects of composition and microstructure on

  17. Development of liquid phase epitaxy-grown (Bi, Gd, Lu)-substituted thin-film iron garnets

    NASA Astrophysics Data System (ADS)

    Nistor, I.; Holthaus, C.; Mayergoyz, I. D.; Krafft, C.

    2006-04-01

    The liquid phase epitaxy growth of single-crystal iron garnet thin films of composition Gd3-x-yLuxBiyFe5-zGazO12 is discussed. The Bi, Lu, and Gd contents are identified for which the garnet films have in-plane magnetization as well as sufficiently large Faraday rotation and can be grown at relatively small melt undercooling temperatures. The results of extensive characterization of the magnetic and optical properties of these garnet films as a function of melt compositions and undercooling are reported.

  18. The electrochemical potential and ionic activity coefficients. A possible correction for Debye-Hückel and Maxwell-Boltzmann equations for dilute electrolyte equilibria.

    PubMed

    van der Weg, P B

    2009-11-15

    When the electrical contribution in the electrochemical potential of ionic species is reduced with a factor two from its traditional value, the ionic activity coefficients are closer to unity and need to account only for the short-range interactions at high concentrations. Such a change is needed to remove inconsistencies in the models and to comply with basic electrostatic principles. This will have serious implications, in many applications. For example, it will cause changes in many of the fundamental models that are used to explain measured data in the dilute range for the various disciplines that embrace classical electrochemistry. Examples are Debye-Hückel and Gouy-Chapman theories; Maxwell-Boltzmann distribution; Nernst theory; Donnan equilibrium, etc. These theories impact a wide range of observable phenomena such as activity coefficients of electrolytes, diffuse double layer capacitance, electrode potentials, membrane potentials, streaming potentials, electro-osmosis, flotation, sedimentation, corrosion, charged micellar behaviour, space-charge semiconductor behaviour, and electrical phenomena in biological tissue, e.g. membranes; cells; and nerves, etcetera. PMID:19656523

  19. Novel one-step headspace dynamic in-syringe liquid phase derivatization-extraction technique for the determination of aqueous aliphatic amines by liquid chromatography with fluorescence detection.

    PubMed

    Muniraj, Sarangapani; Shih, Hou-Kung; Chen, Ying-Fang; Hsiech, Chunming; Ponnusamy, Vinoth Kumar; Jen, Jen-Fon

    2013-06-28

    A novel one-step headspace (HS) dynamic in-syringe (DIS) based liquid-phase derivatization-extraction (LPDE) technique has been developed for the selective determination of two short-chain aliphatic amines (SCAAs) in aqueous samples using high performance liquid chromatography (HPLC) with fluorescence detection (FLD). Methylamine (MA) and dimethylamine (DMA) were selected as model compounds of SCAAs. In this method, a micro-syringe pre-filled with derivatizing reagent solution (9-fluorenylmethyl chloroformate) in the barrel was applied to achieve the simultaneous derivatization and extraction of two methylamines evolved from alkalized aqueous samples through the automated reciprocated movements of syringe plunger. After the derivatization-extraction process, the derivatized phase was directly injected into HPLC-FLD for analysis. Parameters influencing the evolution of methylamines and the HS-DIS-LPDE efficiency, including sample pH and temperature, sampling time, as well as the composition of derivatization reagent, reaction temperature, and frequency of reciprocated plunger movements, were thoroughly examined and optimized. Under optimal conditions, detections were linear in the range of 25-500?gL(-1) for MA and DMA with correlation coefficients all above 0.995. The limits of detection (based on S/N=3) were 5 and 19ngmL(-1) for MA and DMA, respectively. The applicability of the developed method was demonstrated for the determination of MA and DMA in real water samples without any prior cleanup of the sample. The present method provides a simple, selective, automated, low cost and eco-friendly procedure to determine aliphatic amines in aqueous samples. PMID:23591526

  20. Determination of ammonium in aqueous samples using new headspace dynamic in-syringe liquid-phase microextraction with in situ derivitazation coupled with liquid chromatography-fluorescence detection.

    PubMed

    Muniraj, Sarangapani; Yan, Cheing-Tong; Shih, Hou-Kung; Ponnusamy, Vinoth Kumar; Jen, Jen-Fon

    2012-11-19

    A new simultaneous derivatization and extraction method for the preconcentration of ammonia using new one-step headspace dynamic in-syringe liquid-phase microextraction with in situ derivatization was developed for the trace determination of ammonium in aqueous samples by liquid chromatography with fluorescence detection (LC-FLD). The acceptor phase (as derivatization reagent) containing o-phthaldehyde and sodium sulfite was held within a syringe barrel and immersed in the headspace of sample container. The gaseous ammonia from the alkalized aqueous sample formed a stable isoindole derivative with the acceptor phase inside the syringe barrel through the reciprocated movements of plunger. After derivatization-cum-extraction, the acceptor phase was directly injected into LC-FLD for analysis. Parameters affecting the ammonia evolution and the extraction/derivatization efficiency such as sample matrix, pH, temperature, sampling time, and the composition of derivatization reagent, reaction temperature, and frequency of reciprocated plunger, were studied thoroughly. Results indicated that the maximum extraction efficiency was obtained by using 100?L derivatization reagent in a 1-mL gastight syringe under 8 reciprocated movements of plunger per min to extract ammonia evolved from a 20mL alkalized aqueous solution at 70°C (preheated 4min) with 380rpm stirring for 8min. The detection was linear in the concentration range of 0.625-10?M with the correlation coefficient of 0.9967 and detection limit of 0.33?M (5.6ng mL(-1)) based on SN(-1)=3. The method was applied successfully to determine ammonium in real water samples without any prior cleanup of the samples, and has been proved to be a simple, sensitive, efficient and cost-effective procedure for trace ammonium determination in aqueous samples. PMID:23140954

  1. ERRORS IN APPLYING LOW ION-STRENGTH ACTIVITY COEFFICIENT ALGORITHMS TO HIGHER IONIC-STRENGTH AQUATIC MEDIA

    EPA Science Inventory

    The toxicological and regulatory communities are currently exploring the use of free-ion-activity- models as a means of reducing uncertainties in current methods for assessing metals bioavailabi- lity from contaminated aquatic media. While most practitioners would support the des...

  2. ERRORS IN APPLYING LOW IONIC-STRENGTH ACTIVITY COEFFICIENT ALGORITHMS TO HIGHER IONIC-STRENGTH AQUATIC MEDIA

    EPA Science Inventory

    The toxicological and regulatory communities are currently exploring the use of the free-ion-activity (FIA) model both alone and in conjunction with the biotic ligand model (BLM) as a means of reducing uncertainties in current methods for assessing metals bioavailability from aqu...

  3. Immunoassay of paralytic shellfish toxins by moving magnetic particles in a stationary liquid-phase lab-on-a-chip.

    PubMed

    Kim, Myoung-Ho; Choi, Suk-Jung

    2015-04-15

    In this study, we devised a stationary liquid-phase lab-on-a-chip (SLP LOC), which was operated by moving solid-phase magnetic particles in the stationary liquid phase. The SLP LOC consisted of a sample chamber to which a sample and reactants were added, a detection chamber containing enzyme substrate solution, and a narrow channel connecting the two chambers and filled with buffer. As a model system, competitive immunoassays of saxitoxin (STX), a paralytic shellfish toxin, were conducted in the SLP LOC using protein G-coupled magnetic particles (G-MPs) as the solid phase. Anti-STX antibodies, STX-horseradish peroxidase conjugate, G-MPs, and a STX sample were added to the sample chamber and reacted by shaking. While liquids were in the stationary state, G-MPs were transported from the sample chamber to the detection chamber by moving a magnet below the LOC. After incubation to allow the enzymatic reaction to occur, the absorbance of the detection chamber solution was found to be reciprocally related to the STX concentration of the sample. Thus, the SLP LOC may represent a novel, simple format for point-of-care testing applications of enzyme-linked immunosorbent assays by eliminating complicated liquid handling steps. PMID:25460894

  4. Migration of carbon nanotubes from liquid phase to vapor phase in the refrigerant-based nanofluid pool boiling.

    PubMed

    Peng, Hao; Ding, Guoliang; Hu, Haitao

    2011-01-01

    The migration characteristics of carbon nanotubes from liquid phase to vapor phase in the refrigerant-based nanofluid pool boiling were investigated experimentally. Four types of carbon nanotubes with the outside diameters from 15 to 80 nm and the lengths from 1.5 to 10 ?m were used in the experiments. The refrigerants include R113, R141b and n-pentane. The oil concentration is from 0 to 10 wt.%, the heat flux is from 10 to 100 kW·m-2, and the initial liquid-level height is from 1.3 to 3.4 cm. The experimental results indicate that the migration ratio of carbon nanotube increases with the increase of the outside diameter or the length of carbon nanotube. For the fixed type of carbon nanotube, the migration ratio decreases with the increase of the oil concentration or the heat flux, and increases with the increase of the initial liquid-level height. The migration ratio of carbon nanotube increases with the decrease of dynamic viscosity of refrigerant or the increase of liquid phase density of refrigerant. A model for predicting the migration ratio of carbon nanotubes in the refrigerant-based nanofluid pool boiling is proposed, and the predictions agree with 92% of the experimental data within a deviation of ±20%. PMID:21711730

  5. Migration of carbon nanotubes from liquid phase to vapor phase in the refrigerant-based nanofluid pool boiling

    PubMed Central

    2011-01-01

    The migration characteristics of carbon nanotubes from liquid phase to vapor phase in the refrigerant-based nanofluid pool boiling were investigated experimentally. Four types of carbon nanotubes with the outside diameters from 15 to 80 nm and the lengths from 1.5 to 10 ?m were used in the experiments. The refrigerants include R113, R141b and n-pentane. The oil concentration is from 0 to 10 wt.%, the heat flux is from 10 to 100 kW·m-2, and the initial liquid-level height is from 1.3 to 3.4 cm. The experimental results indicate that the migration ratio of carbon nanotube increases with the increase of the outside diameter or the length of carbon nanotube. For the fixed type of carbon nanotube, the migration ratio decreases with the increase of the oil concentration or the heat flux, and increases with the increase of the initial liquid-level height. The migration ratio of carbon nanotube increases with the decrease of dynamic viscosity of refrigerant or the increase of liquid phase density of refrigerant. A model for predicting the migration ratio of carbon nanotubes in the refrigerant-based nanofluid pool boiling is proposed, and the predictions agree with 92% of the experimental data within a deviation of ±20%. PMID:21711730

  6. Removal of dichloromethane from waste gases in one- and two-liquid-phase stirred tank bioreactors and biotrickling filters.

    PubMed

    Bailón, Laura; Nikolausz, Marcell; Kästner, Matthias; Veiga, María C; Kennes, Christian

    2009-01-01

    The removal of dichloromethane (DCM) from polluted air was studied both in biotrickling filters and in continuous stirred tank bioreactors, using either a single-liquid aqueous phase or a combination of an aqueous-organic liquid phase. The presence of the organic phase, i.e. silicone oil, at a volume ratio of 10% of the liquid phase, increased the maximum EC by about 25% in the BTF, reaching 200 gm(3)/h, and by as much as 300% in the CSTB, reaching 350 gm(3)/h. Based on data of chloride release in the aqueous phase and carbon dioxide production in the gas phase, complete dechlorination and mineralization of the pollutant could be confirmed. When applying shock loads, a more stable behaviour was observed in the presence of the organic phase. Generally, the completely mixed reactors were also more stable than the plug-flow biotrickling filters, irrespective of the presence of the organic phase. The use of molecular techniques allowed showing that the originally inoculated DCM-degrading Hyphomicrobium strains remained present, although not dominant, after long-term bioreactor operation. Different new bacterial populations did also appear in the systems, some of which were unable to degrade DCM. PMID:18945466

  7. Manganese oxide nanosheets and a 2D hybrid of graphene–manganese oxide nanosheets synthesized by liquid-phase exfoliation

    NASA Astrophysics Data System (ADS)

    Coelho, João; Mendoza-Sánchez, Beatriz; Pettersson, Henrik; Pokle, Anuj; McGuire, Eva K.; Long, Edmund; McKeon, Lorcan; Bell, Alan P.; Nicolosi, Valeria

    2015-06-01

    Manganese oxide nanosheets were synthesized using liquid-phase exfoliation that achieved suspensions in isopropanol (IPA) with concentrations of up to 0.45 mg ml?1. A study of solubility parameters showed that the exfoliation was optimum in N,N-dimethylformamide followed by IPA and diethylene glycol. IPA was the solvent of choice due to its environmentally friendly nature and ease of use for further processing. For the first time, a hybrid of graphene and manganese oxide nanosheets was synthesized using a single-step co-exfoliation process. The two-dimensional (2D) hybrid was synthesized in IPA suspensions with concentrations of up to 0.5 mg ml?1 and demonstrated stability against re-aggregation for up to six months. The co-exfoliation was found to be a energetically favorable process in which both solutes, graphene and manganese oxide nanosheets, exfoliate with an improved yield as compared to the single-solute exfoliation procedure. This work demonstrates the remarkable versatility of liquid-phase exfoliation with respect to the synthesis of hybrids with tailored properties, and it provides proof-of-concept ground work for further future investigation and exploitation of hybrids made of two or more 2D nanomaterials that have key complementary properties for various technological applications.

  8. The CPA Equation of State and an Activity Coefficient Model for Accurate Molar Enthalpy Calculations of Mixtures with Carbon Dioxide and Water/Brine

    E-print Network

    Myint, P C; Firoozabadi, A

    2015-01-01

    Thermodynamic property calculations of mixtures containing carbon dioxide (CO$_2$) and water, including brines, are essential in theoretical models of many natural and industrial processes. The properties of greatest practical interest are density, solubility, and enthalpy. Many models for density and solubility calculations have been presented in the literature, but there exists only one study, by Spycher and Pruess, that has compared theoretical molar enthalpy predictions with experimental data. In this report, we recommend two different models for enthalpy calculations: the CPA equation of state by Li and Firoozabadi, and the CO$_2$ activity coefficient model by Duan and Sun. We show that the CPA equation of state, which has been demonstrated to provide good agreement with density and solubility data, also accurately calculates molar enthalpies of pure CO$_2$, pure water, and both CO$_2$-rich and aqueous (H$_2$O-rich) mixtures of the two species. It is applicable to a wider range of conditions than the Spy...

  9. Diffusion coefficient anisotropy near the liquid-vapour interface for simple fluid

    NASA Astrophysics Data System (ADS)

    Lebovka, N. I.; Mank, V. V.

    1990-07-01

    The estimation of the translation diffusion-coefficient profiles D(z) near the liquid-vapour interface of a simple Lennard-Jones (LJ) fluid is done. The calculations are based on the Kirkwood-Rice model for the diffusion in fluids. The diffusion process is shown to reveal the anisotropic behaviour in the vicinity of the interface. In the liquid phase, the diffusion coefficient normal to the interface exceeds the parallel one, and the situation is vice versa in the vapour phase.

  10. Modeling of the Phase behavior of light (C2 & C3) olefins in liquid phase epoxidation systems and experimental determination of gas/liquid mass transfer coefficients

    E-print Network

    Ghanta, Madhav

    2008-01-01

    Conventional technologies for the selective epoxidation of olefins such as ethylene and propylene to form their corresponding epoxides are either non selective and/or produce much waste. A novel biphasic process for the ...

  11. Commercial-scale demonstration of the Liquid Phase Methanol (LPMEOH{trademark}) process. Technical progress report number 11, January 1--March 31, 1997

    SciTech Connect

    NONE

    1997-06-11

    During this quarter, the third draft of the Topical Report on Process Economics Studies was issued for review. A recommendation to continue with design verification testing on the coproduction of methanol and dimethyl ether (DME) was made. A liquid phase dimethyl ether (LPDME) catalyst system with reasonable long-term activity and stability is being developed, and a decision to proceed with a proof-of-concept test run at the LaPorte Alternative Fuels Development Unit (AFDU) is pending the release of a memo from Air Products on the catalyst targets and corresponding economics for a commercially successful LPDME catalyst. The off-site product-use test plan is to be updated in June of 1997. During this quarter, Air Products and Acurex Environmental Corporation continued developing the listing of product-use test participants who are involved in fuel cell, transportation, and stationary power plant applications. Start-up activities (Task 3.1) began during the reporting period, and coal-derived synthesis gas (syngas) was introduced to the demonstration unit. The recycle compressor was tested successfully on syngas at line pressure of 700 psig, and the reactor loop reached 220 C for carbonyl burnout. Iron carbonyl in the balanced gas feed remained below the 10 ppbv detection limit for all samples but one. Within the reactor loop, iron carbonyl levels peaked out near 200 ppbv after about 40 hours on-stream, before decreasing to between 10--20 ppbv at 160 hours on -stream. Nickel carbonyl measurements reached a peak of about 60 ppbv, and decreased at all sampling locations to below the 10 ppbv detection limit by 70 hours on-stream. Catalyst activation of the nine 2,250 lb batches required for the initial catalyst charge began and concluded. All batches met or slightly exceeded the theoretical maximum uptake of 2.82 SCF of reducing gas/lb catalyst.

  12. Modeling solubility, acid-base properties and activity coefficients of amoxicillin, ampicillin and (+)6-aminopenicillanic acid, in NaCl(aq) at different ionic strengths and temperatures.

    PubMed

    Crea, Francesco; Cucinotta, Daniela; De Stefano, Concetta; Milea, Demetrio; Sammartano, Silvio; Vianelli, Giuseppina

    2012-11-20

    The total solubility of three penicillin derivatives was determined, in pure water and NaCl aqueous solutions at different salt concentrations (from ?0.15 to 1.0 mol L(-1) for ampicillin and amoxicillin, and from ?0.05 to 2.0 mol L(-1) for (+)6-aminopenicillanic acid), using the shake-flask method for generating the saturated solutions, followed by potentiometric analysis. The knowledge of the pH of solubilization and of the protonation constants determined in the same experimental conditions, allowed us to calculate, by means of the mass balance equations, the solubility of the neutral species at different ionic strength values, to model its dependence on the salt concentration and to determine the corresponding values at infinite dilution. The salting parameter and the activity coefficients of the neutral species were calculated by the Setschenow equation. The protonation constants of ampicillin and amoxicillin, determined at different temperatures (from T=288.15 to 318.15K), from potentiometric and spectrophotometric measurements, were used to calculate, by means of the Van't Hoff equation, the temperature coefficients at different ionic strength values and the corresponding protonation entropies. The protonation enthalpies of the (+)6-aminopenicillanic acid were determined by isoperibol calorimetric titrations at T=298.15K and up to I=2.0 mol L(-1). The dependence of the protonation constants on ionic strength was modeled by means of the Debye-Hückel and SIT (Specific ion Interaction Theory) approaches, and the specific interaction parameters of the ionic species were determined. The hydrolysis of the ?-lactam ring was studied by spectrophotometric and H NMR investigations as a function of pH, ionic strength and time. Potentiometric measurements carried out on the hydrolyzed (+)6-aminopenicillanic acid allowed us to highlight that the opened and the closed ?-lactam forms of the (+)6-aminopenicillanic acid have quite different acid-base properties. An analysis of literature solubility, protonation constants, enthalpies and activity coefficients is reported too. PMID:22903046

  13. Novel synthesis of manganese and vanadium mixed oxide (V{sub 2}O{sub 5}/OMS-2) as an efficient and selective catalyst for the oxidation of alcohols in liquid phase

    SciTech Connect

    Mahdavi, Vahid, E-mail: v-mahdavi@araku.ac.ir; Soleimani, Shima

    2014-03-01

    Graphical abstract: Oxidation of various alcohols is studied in the liquid phase over new composite mixed oxide (V{sub 2}O{sub 5}/OMS-2) catalyst using tert-butyl hydroperoxide (TBHP). The activity of V{sub 2}O{sub 5}/OMS-2 samples was considerably increased with respect to OMS-2 catalyst and these samples are found to be suitable for the selective oxidation of alcohols. - Highlights: • V{sub 2}O{sub 5}/K-OMS-2 with different V/Mn molar ratios prepared by the impregnation method. • Oxidation of alcohols was studied in the liquid phase over V{sub 2}O{sub 5}/K-OMS-2 catalyst. • V{sub 2}O{sub 5}/K-OMS-2 catalyst had excellent activity for alcohol oxidation. • Benzyl alcohol oxidation using excess TBHP followed a pseudo-first order kinetic. • The selected catalyst was reused without significant loss of activity. - Abstract: This work reports the synthesis and characterization of mixed oxide vanadium–manganese V{sub 2}O{sub 5}/K-OMS-2 at various V/Mn molar ratios and prepared by the impregnation method. Characterization of these new composite materials was made by elemental analysis, BET, XRD, FT-IR, SEM and TEM techniques. Results of these analyses showed that vanadium impregnated samples contained mixed phases of cryptomelane and crystalline V{sub 2}O{sub 5} species. Oxidation of various alcohols was studied in the liquid phase over the V{sub 2}O{sub 5}/K-OMS-2 catalyst using tert-butyl hydroperoxide (TBHP) and H{sub 2}O{sub 2} as the oxidant. Activity of the V{sub 2}O{sub 5}/K-OMS-2 samples was increased considerably with respect to K-OMS-2 catalyst due to the interaction of manganese oxide and V{sub 2}O{sub 5}. The kinetic of benzyl alcohol oxidation using excess TBHP over V{sub 2}O{sub 5}/K-OMS-2 catalyst was investigated at different temperatures and a pseudo-first order reaction was determined with respect to benzyl alcohol. The effects of reaction time, oxidant/alcohol molar ratio, reaction temperature, solvents, catalyst recycling potential and leaching were investigated.

  14. Modeling, design, packing and experimental analysis of liquid-phase shear-horizontal surface acoustic wave sensors

    NASA Astrophysics Data System (ADS)

    Pollard, Thomas B

    Recent advances in microbiology, computational capabilities, and microelectromechanical-system fabrication techniques permit modeling, design, and fabrication of low-cost, miniature, sensitive and selective liquid-phase sensors and lab-on-a-chip systems. Such devices are expected to replace expensive, time-consuming, and bulky laboratory-based testing equipment. Potential applications for devices include: fluid characterization for material science and industry; chemical analysis in medicine and pharmacology; study of biological processes; food analysis; chemical kinetics analysis; and environmental monitoring. When combined with liquid-phase packaging, sensors based on surface-acoustic-wave (SAW) technology are considered strong candidates. For this reason such devices are focused on in this work; emphasis placed on device modeling and packaging for liquid-phase operation. Regarding modeling, topics considered include mode excitation efficiency of transducers; mode sensitivity based on guiding structure materials/geometries; and use of new piezoelectric materials. On packaging, topics considered include package interfacing with SAW devices, and minimization of packaging effects on device performance. In this work novel numerical models are theoretically developed and implemented to study propagation and transduction characteristics of sensor designs using wave/constitutive equations, Green's functions, and boundary/finite element methods. Using developed simulation tools that consider finite-thickness of all device electrodes, transduction efficiency for SAW transducers with neighboring uniform or periodic guiding electrodes is reported for the first time. Results indicate finite electrode thickness strongly affects efficiency. Using dense electrodes, efficiency is shown to approach 92% and 100% for uniform and periodic electrode guiding, respectively; yielding improved sensor detection limits. A numerical sensitivity analysis is presented targeting viscosity using uniform-electrode and shear-horizontal mode configurations on potassium-niobate, langasite, and quartz substrates. Optimum configurations are determined yielding maximum sensitivity. Results show mode propagation-loss and sensitivity to viscosity are correlated by a factor independent of substrate material. The analysis is useful for designing devices meeting sensitivity and signal level requirements. A novel, rapid and precise microfluidic chamber alignment/bonding method was developed for SAW platforms. The package is shown to have little effect on device performance and permits simple macrofluidic interfacing. Lastly, prototypes were designed, fabricated, and tested for viscosity and biosensor applications; results show ability to detect as low as 1% glycerol in water and surface-bound DNA crosslinking.

  15. Exploring the solid-liquid phase change of an adapted Dzugutov model using generalized replica exchange method.

    PubMed

    Lu, Qing; Kim, Jaegil; Straub, John E

    2012-07-26

    The generalized replica exchange method (gREM) is applied to simulate a solid-liquid phase change in an adapted Dzugutov model system. The idea of gREM is to incorporate the merit of sampling from a generalized ensemble into the replica exchange paradigm. The generalized ensemble weights are determined from effective temperatures tailored for this system, through an inverse mapping strategy. The ordered and disordered phases are smoothly joined together through a succession of unimodal energy distributions, providing a continuous transformation from an isotropic liquid into an amorphous solid phase under the given condition. The phase change temperature is determined by evaluation of various thermodynamic and structural order parameters. The increasing tendency for icosahedral local order under cooling is quantified using bond order parameters. The ergodic measure is used to demonstrate the advantage of gREM over the traditional temperature-based REM in sampling the phase change region. PMID:22452532

  16. Liquid-Phase Epitaxial Growth of ZnS, ZnSe and Their Mixed Compounds Using Te as Solvent

    NASA Astrophysics Data System (ADS)

    Nakamura, Hiroshi; Aoki, Masaharu

    1981-01-01

    Epitaxial layers of ZnS, ZnSe and their mixed compounds were grown on ZnS substrates by the liquid-phase epitaxial growth (LPE) method using Te as the solvent. The open-tube slide-boat technique was used, and a suitable starting temperature for growth was found to be 850°C for ZnS and 700-800°C for ZnSe. The ZnS epitaxial layers grown on {111}A and {111}B oriented ZnS substrates were thin (˜1 ?m) and smooth, had low, uniform Te concentrations (˜0.1 at.%) and were highly luminescent. The ZnSe epitaxial layers were relatively thick (10-30 ?m) and had fairly high Te concentrations (a few at.%). Various mixed compound ZnS1-xSex were also grown on ZnS substrates.

  17. Investigations on the undersaturated liquid phase epitaxial growth of Al xGa 1- xAs

    NASA Astrophysics Data System (ADS)

    Jeganathan, K.; Qhalid Fareed, R. S.; Baskar, K.; Ramasamy, P.; Kumar, J.

    Al xGa 1- xAs hetero-epitaxial layers have been realised from undersaturated Al/Ga/GaAs melt using liquid-phase epitaxy (LPE). We have not observed any change of layer thickness after a certain period of isothermal contact of GaAs(1 0 0) substrate with an undersaturated melt. Theoretically, we have demonstrated that a small change in the interfacial energy between the substrate and melt provides the driving force for Al xGa 1- xAs heteroepitaxial layers. AFM image reveals the atomic flat terraces running parallel to the (1 1 0) direction. The grading of aluminium composition from surface to interface has been confirmed using photoelectron spectroscopy. Details on the growth conditions and on the characterisation results are presented.

  18. Capillary electrophoresis determination of nonsteroidal anti-inflammatory drugs in wastewater using hollow fiber liquid-phase microextraction.

    PubMed

    Villar Navarro, Mercedes; Ramos Payán, María; Fernández-Torres, Rut; Bello-López, Miguel A; Callejón Mochón, Manuel; Guiráum Pérez, Alfonso

    2011-08-01

    The presence of pharmaceuticals in the environment due to growing worldwide consumption has become an important problem that requires analytical solutions. This paper describes a CE determination for several nonsteroidal anti-inflammatory drugs (ibuprofen, naproxen, ketoprofen, diclofenac, ketorolac, aceclofenac and salicylic acid) in environmental waters using hollow fiber membrane liquid-phase microextraction. The extraction was carried out using a polypropylene membrane supporting dihexyl ether and the electrophoretic separation was performed in acetate buffer (30?mM, pH 4) using ACN as the organic modifier. Detection limits between 0.25 and 0.86?ng/mL were obtained, respectively. The method could be applied to the direct determination of the seven anti-inflammatories in wastewaters, and five of them have been determined or detected in different urban wastewaters. PMID:23479790

  19. Effect of water presence on methyl tert-butyl ether and ethyl tert-butyl ether liquid-phase syntheses

    SciTech Connect

    Cunill, F.; Vila, M.; Izquierdo, J.F.; Iborra, M.; Tejero, J. (Univ. of Barcelona (Spain))

    1993-03-01

    Equilibrium constants for the liquid-phase synthesis of methyl tert-butyl ether (MTBE) and ethyl tert-butyl ether (ETBE) were determined experimentally in the temperature range 40-80 C, using an initial water percentage range in the alcohol of 1.4-5 wt%. The initial molar alcohol-isobutylene ratio varied from 0.8 to 1.44. Both systems behave nonideally, and the equilibrium constants found agree with those determined without initial water quoted in the literature. In experimental kinetic runs performed at 40 C, ETBE and MTBE production rates are strongly lowered by the initial water presence. This inhibitor effect disappears as water is converted into tert-butyl alcohol (TBA). The TBA equilibrium is reached faster than those of the ethers, and the residual water is rather small.

  20. Two methods for characterizing the electrical properties of InAsSb film grown by liquid phase epitaxy

    NASA Astrophysics Data System (ADS)

    Lv, Yingfei; Hu, Shuhong; Xu, Yonggang; Wang, Yang; Yu, Guolin; Dai, Ning

    2015-04-01

    High-quality InAs1-xSbx films with x=0.06 have been successfully grown on InAs (100) substrates by liquid phase epitaxy. Two methods are used to characterize the electrical properties of InAsSb film. One is to grow InAsSb epilayer on p-type InAs substrate, which, in combination with the n-type epilayer, forms a p-n junction to prevent the parallel conduction from the substrate. The other is that both the conductive InAs substrate and the dislocation layer between InAs and InAsSb are removed completely by chemical mechanical polishing method to get InAsSb film glued onto insulating sapphire substrate. The influence of conductive InAs substrate on the electrical properties of InAsSb film is eliminated effectively.

  1. Hollow-fiber liquid-phase microextraction combined with capillary electrophoresis for trace analysis of sulfonamide compounds.

    PubMed

    Tong, Fanghong; Zhang, Yang; Chen, Fang; Li, Ying; Ma, Guanhua; Chen, Yanping; Liu, Kun; Dong, Jiaming; Ye, Jiannong; Chu, Qingcui

    2013-12-30

    A hollow-fiber liquid-phase microextraction (HF-LPME) method has been developed for the preconcentration of trace sulfonamides in water samples. Six commonly used sulfonamides including sulfamethazine (SMZ), sulfamerazine (SMR), sulfadiazine (SDZ), sulfadimethoxine (SDM), sulfamethoxazole (SMX), and sulfathiazole (STZ) were determined by CE with electrochemical detection (CE-ED) after microextraction. Several factors that affect extraction efficiency, separation, and detection were investigated. Under the optimum conditions, above sulfonamide compounds could achieve baseline separation within 35min, exhibiting a linear calibration over three orders of magnitude (r(2)?0.998); the obtained enrichment factors were between 121 (for SDZ) and 996 (for SDM), and the LODs were in the range of 0.033-0.44ng/mL. The proposed HF-LPME/CE-ED method has been applied for the sensitive analyses of the real-world water samples with recoveries in the range of 75.1-109%. PMID:24269907

  2. Characterization of Transient Liquid-Phase Bonded Joints in a Copper-Beryllium Alloy with Silver-base Interlayer

    NASA Astrophysics Data System (ADS)

    Mazar Atabaki, M.

    2012-06-01

    Transient liquid-phase diffusion bonding was employed to join copper-beryllium alloy using three silver-base interlayers. The bonding process was carried out at different temperatures under argon and vacuum atmospheres for various hold times. Interfacial microstructures were examined by scanning electron microscopy. Microhardness, tensile, and fatigue tests were used for evaluating the mechanical properties. Maximum tensile strength of 156.45 MPa was obtained for bonds processed at 780 °C. Fatigue strength of bonds fabricated in vacuum was higher than those of bonds prepared in argon atmosphere. The diffusion of the main elements from the interlayers into the base metal was the main controlling factor pertaining to the microstructural evolution of the joint interface.

  3. Vulcanization reaction of squalene and S8 powder studied by Sulfur K-edge NEXAFS under liquid phase

    NASA Astrophysics Data System (ADS)

    Yagi, S.; Menjo, Y.; Tsukada, C.; Ogawa, S.; Kutluk, G.; Namatame, H.; Taniguchi, M.

    2015-03-01

    Vulcanized rubber materials are useful in our surroundings. However, detail structure and reaction are not revealed even in present. Since squalene molecule possesses some same properties compared with natural rubber, we have prepared the samples of vulcanized squalene at 140 °C for several hours. To understand the vulcanization reaction,sulfur K-edge NEXAFS measurements have been carried out for the vulcanized squalene under liquid phase with He-path system and fluorescence detection mode. Moreover, we have tried curve fitting analysis of NEXAFS spectra. The results indicate that the squalene has been vulcanized by the S8 molecule at 140 °C and the S8 molecule length is shortened from 8 to 5-6 after the vulcanization reaction.

  4. Multiplexed gas sensor based on heterogeneous metal oxide nanomaterial array enabled by localized liquid-phase reaction.

    PubMed

    Yang, Daejong; Fuadi, M Kasyful; Kang, Kyungnam; Kim, Donghwan; Li, Zhiyong; Park, Inkyu

    2015-05-20

    A novel method for the selective and localized synthesis of nanomaterials and their in situ integration based on serial combination of localized liquid-phase reaction has been developed for the fabrication of heterogeneous nanomaterial array. This method provides simple, fast and cost-effective fabrication process by using well-controlled thermal energy and therefore solves the challenging problems of assembly and integration of heterogeneous nanomaterial array in functional microelectronic devices. We have fabricated a parallel array of TiO2 nanotubes, CuO nanospikes, and ZnO nanowires, which exhibited adequate gas sensing response. Furthermore, we could approximately determine individual gas concentrations in a mixture gas consisting of 0-2 ppm of NO2 and 0-800 ppm of CO gas species by analyzing multiple data from an array of heterogeneous sensing nanomaterials. PMID:25902930

  5. Combination of hollow-fiber liquid-phase microextraction and capillary electrophoresis for pioglitazone and its main metabolites determination in rat liver microsomal fraction.

    PubMed

    Calixto, Leandro Augusto; Bonato, Pierina Sueli

    2013-03-01

    Pioglitazone (PGZ), a thiazolidinedione antidiabetic agent, is reported as a potent and selective activator of peroxisome proliferator-activated receptor ? (PPAR ?). This drug has been widely prescribed for the treatment of Type 2 diabetes mellitus. In this regard, this manuscript presents, for the first time, an alternative electrophoretic method for PGZ and its main metabolites determination in rat liver microsomal fraction. The electrophoretic analyses were performed using an uncoated fused-silica capillary of 50 ?m id, 48 cm in total length and 40 cm in effective length, and 50 mmol/L sodium phosphate buffer solution (pH 2.5). All experiments were carried out under the normal mode. The capillary temperature was set at 35°C and a constant voltage of +30 kV was applied during the analyses. Samples were introduced into the capillary by hydrodynamic injection (50 mbar, 15 s) and detection was performed at 190 nm. The sample preparation procedure, based on hollow-fiber liquid-phase microextraction, was optimized using multifactorial experiments. Next, the following optimal condition was established: sample agitation at 1500 rpm, extraction for 15 min, 0.01 mol/L hydrochloric acid as acceptor phase, 1-octanol as organic phase, and donor phase pH adjustment to 6.0. The method demonstrated LOQs of 200 ng/mL. Additionally, it was linear over the concentration range of 200-25,000 ng/mL for PGZ and 200-2000 ng/mL for the metabolites. Finally, the validated method was employed to study the in vitro metabolism of PGZ using rat liver microsomal fraction. PMID:23335111

  6. Normal spectral emissivity near 680 nm at melting and in the liquid phase for 18 metallic elements

    NASA Astrophysics Data System (ADS)

    Pottlacher, G.; Boboridis, K.; Cagran, C.; Hüpf, T.; Seifter, A.; Wilthan, B.

    2013-09-01

    Optical and thermophysical properties of pure metals at the melting point and in the liquid phase are of general interest for technological applications. This is especially true for those metals that are commonly applied. Many of these elements are used either in their pure form or as alloying components. Due to their widespread use in industry an ongoing need for new and more accurate data exists. Based on an ohmic pulse-heating apparatus, properties of conducting materials can be obtained from temperatures of about 1200 K, at which most metals are in the solid state, up to about 5000 K in the liquid state. To enable a fast and accurate temperature measurement over such a vast range, pyrometric temperature detection based on Planck's radiation law is employed. Furthermore, a microsecond-resolution ellipsometric device with no moving parts, called ?s-DOAP (Division-of-Amplitude-Photopolarimeter) as first described by Azzam [1], is applied to measure normal spectral emissivity close to the wavelength of the pyrometer (650 nm). In the present paper, measurements of normal spectral emissivity at 684.5 nm, obtained by means of the above-mentioned pulse-heating technique combined with a ?s-DOAP, are summarized for 18 metals, namely cobalt (Co), copper (Cu), gold (Au), hafnium (Hf-3%Zr), iron (Fe), iridium (Ir), molybdenum (Mo), nickel (Ni), niobium (Nb), palladium (Pd), platinum (Pt), rhenium (Re), silver (Ag), tantalum (Ta), titanium (Ti), tungsten (W), vanadium (V) and zirconium (Zr). The results are very important in order to eliminate uncertainties arising from the unknown behavior of emissivity at melting and in the liquid phase when investigating temperature-dependent thermophysical properties.

  7. Nanosecond Pulsed Discharges in Liquid Phase: Optical diagnostics of positive versus negative modes of initiation in water

    NASA Astrophysics Data System (ADS)

    Seepersad, Yohan; Fridman, Alexander; Dobrynin, Danil; Applied Physics Group Team

    2013-09-01

    Recent work on nanosecond pulsed discharges in liquids has shown the possibility of producing plasma directly in the liquid phase without bubble formation or heating of the liquid. Paramount to understanding the physical processes leading to this phenomenon is a thorough understanding of the way these discharges behave under various conditions. This work explores the development of nanosecond pulsed discharges in water, for both positively and negatively applied pulses in a pin-to-plane configuration. Time resolved nanosecond ICCD imaging is used to trace the development of the discharge for applied voltages up to 24 kV. From the results we are able to identify breakdown thresholds at which discharge is initiated for both modes. At voltages below the critical breakdown value, Schlieren and shadowgraphy techniques are used to investigate perturbations in the liquid layers near the electrode tip as a consequence of these fat rising pulses. Recent work on nanosecond pulsed discharges in liquids has shown the possibility of producing plasma directly in the liquid phase without bubble formation or heating of the liquid. Paramount to understanding the physical processes leading to this phenomenon is a thorough understanding of the way these discharges behave under various conditions. This work explores the development of nanosecond pulsed discharges in water, for both positively and negatively applied pulses in a pin-to-plane configuration. Time resolved nanosecond ICCD imaging is used to trace the development of the discharge for applied voltages up to 24 kV. From the results we are able to identify breakdown thresholds at which discharge is initiated for both modes. At voltages below the critical breakdown value, Schlieren and shadowgraphy techniques are used to investigate perturbations in the liquid layers near the electrode tip as a consequence of these fat rising pulses. This work was supported by Defense Advanced Research Projects Agency (grant #DARPA-BAA-11-31).

  8. Commercial-scale demonstration of the Liquid Phase Methanol process. Technical progress report number 8, April 1--June 30, 1996

    SciTech Connect

    NONE

    1996-12-31

    The project involves the construction of an 80,000 gallon per day (260 tons per day (TPD)) methanol unit utilizing coal-derived synthesis gas from Eastman`s integrated coal gasification facility. The new equipment consists of synthesis gas feed preparation and compression facilities, the liquid phase reactor and auxiliaries, product distillation facilities, and utilities. The technology to be demonstrated is the product of a cooperative development effort by Air Products and DOE in a program that started in 1981. Developed to enhance electric power generation using integrated gasification combined cycle (IGCC) technology, the LPMEOH{trademark} process is ideally suited for directly processing gases produced by modern-day coal gasifiers. Originally tested at a small (10 TPD), DOE-owned experimental unit in LaPorte, Texas, the technology provides several improvements essential for the economic coproduction of methanol and electricity directly from gasified coal. This liquid phase process suspends fine catalyst particles in an inert liquid, forming a slurry. The slurry dissipates the heat of the chemical reaction away from the catalyst surface, protecting the catalyst and allowing the methanol synthesis reaction to proceed at higher rates. At the Eastman complex, the technology is being integrated with existing coal-gasifiers. A carefully developed test plan will allow operations at Eastman to simulate electricity demand load-following in coal-based IGCC facilities. The operations will also demonstrate the enhanced stability and heat dissipation of the conversion process, its reliable on/off operation, and its ability to produce methanol as a clean liquid fuel without additional upgrading.

  9. Synthesis of dimethyl ether and alternative fuels in the liquid phase from coal-derived synthesis gas

    SciTech Connect

    Bhatt, B.L.

    1992-09-01

    As part of the DOE-sponsored contract for the Synthesis of Dimethyl Ether (DME) and Alternative Fuels in the Liquid Phase from Coal- Derived Syngas, the single-step, slurry phase DME synthesis process was developed. The development involved screening of catalyst systems, process variable studies, and catalyst life studies in two 300 ml stirred autoclaves. As a spin-off of the Liquid Phase Methanol (LPMEOH*) process, the new process significantly improves the syngas conversion efficiency of the LPMEOH process. This improvement can be achieved by replacing a portion of methanol catalyst with a dehydration catalyst in the reactor, resulting in the product methanol being converted to DME, thus avoiding the thermodynamic equilibrium constraint of the methanol reaction. Overall, this increases syngas conversion per-pass. The selectivity and productivity of DME and methanol are affected by the catalyst system employed as well as operating conditions. A preferred catalyst system, consisting of a physical mixture of a methanol catalyst and a gamma alumina, was identified. An improvement of about 50% in methanol equivalent productivity was achieved compared to the LPMEOH process. Results from the process variable study indicate that higher pressure and CO[sub 2] removal benefit the process significantly. Limited life studies performed on the preferred catalyst system suggest somewhat higher than expected deactivation rate for the methanol catalyst. Several DME/methanol mixtures were measured for their key properties as transportation fuels. With small amounts of DME added, significant improvements in both flash points and Reid Vapor Pressure (RVP) were observed over the corresponding values of methanol alone.

  10. Advance Digital Imaging Process for Tungsten Alloys Liquid-Phase Sintered in Microgravity W. B Goodwin, University of Tennessee, SURF 2009 Fellow

    E-print Network

    Li, Mo

    Advance Digital Imaging Process for Tungsten Alloys Liquid-Phase Sintered in Microgravity W. B boundary energy s-s through Young's equation given below. 2cos(/2)=s-s/s-l (1) The true 3D dihedral angle is to develop a digital image processing algorithm to rapidly detect and measure dihedral angles in binary

  11. MECHANISM OF INHIBITING EFFECT OF HYDROFLUORIC ACID IN FUMING NITRIC ACID ON LIQUID-PHASE CORROSION OF ALUMINUM AND STEEL ALLOYS

    Microsoft Academic Search

    D. M. Mason; J. B. Rittenhouse

    1958-01-01

    The inhibiting effect of hydrofluoric acid in fuming nitric acid on the ; liquid-phase corrosion of aluminum alloys and iron alloys is found to be ; dependent primarily on the formation of a tenacious insolable fluoride compound ; of aluminum or iron, respectively, on the surface of the metal. This mechanism ; is discussed in relation to: (1) solubility data

  12. Characterization of solar cells for space applications. Volume 14: Electrical characteristics of Hughes liquid phase epitaxy gallium arsenide solar cells as a function of intensity, temperature and irradiation

    NASA Technical Reports Server (NTRS)

    Anspaugh, B. E.; Downing, R. G.; Miyahira, T. F.; Weiss, R. S.

    1981-01-01

    Electrical characteristics of liquid phase epitaxy, P/N gallium aluminum arsenide solar cells are presented in graphical and tabular format as a function of solar illumination intensity and temperature. The solar cells were exposed to 1 MeV electron fluences of, respectively, 0, one hundred trillion, one quadrillion, and ten quadrillion e/sq cm.

  13. A dispersive scattering centers-based strategy for dramatically enhancing the photocatalytic efficiency of photocatalysts in liquid-phase photochemical processes: a case of Ag nanosheets.

    PubMed

    Liu, Chang; Kuang, Qin; Jin, Ming-Shang; Zhang, Jia-Wei; Han, Xi-Guang; Xie, Zhao-Xiong; Zheng, Lan-Sun

    2013-03-01

    A dispersive scattering centers-based strategy was proposed to enhance the photocatalytic efficiency of photocatalysts in liquid-phase photochemical processes. Photocatalytic efficiencies of the photocatalyst, Degussa P25, in water splitting and photodegradation were markedly enhanced by using Ag nanosheets as dispersive scattering centers. PMID:23364465

  14. Free energy surface of ST2 water near the liquid-liquid phase transition Peter H. Poole, Richard K. Bowles, Ivan Saika-Voivod, and Francesco Sciortino

    E-print Network

    Sciortino, Francesco

    Free energy surface of ST2 water near the liquid-liquid phase transition Peter H. Poole, Richard K://jcp.aip.org/about/rights_and_permissions #12;THE JOURNAL OF CHEMICAL PHYSICS 138, 034505 (2013) Free energy surface of ST2 water near umbrella sampling Monte Carlo simulations to evaluate the free energy surface of the ST2 model of water

  15. Extraction and preconcentration of ?-blockers in human urine for analysis with high performance liquid chromatography by means of carrier-mediated liquid phase microextraction

    Microsoft Academic Search

    Li Zhang; Xiaoli Su; Chenggong Zhang; Li Ouyang; Qingji Xie; Ming Ma; Shouzhuo Yao

    2010-01-01

    A novel method was developed for the analysis of four ?-blockers, namely sotalol, carteolol, bisoprolol, and propranolol, in human urine by coupling carrier-mediated liquid phase microextraction (CM-LPME) to high performance liquid chromatography (HPLC). By adding an appropriate carrier in organic phase, simultaneous extraction and enrichment of hydrophilic (sotalol, carteolol, and bisoprolol) and hydrophobic (propranolol) drugs were achieved. High enrichment factors

  16. Novel approaches to low temperature transient liquid phase bonding in the In-Sn/Cu and In-Sn-Bi/Cu systems

    E-print Network

    Fischer, David S., Ph. D. Massachusetts Institute of Technology

    2008-01-01

    A fluxless low temperature transient liquid phase (LTTLP) bonding process was studied as a method of producing Cu/Cu joints below 125°C and 75°C using interlayer alloys from the In-Sn and In-Sn-Bi systems. Using thermodynamic ...

  17. Regioselective biooxidation of (+)-valencene by recombinant E. coli expressing CYP109B1 from Bacillus subtilis in a two-liquid-phase system

    PubMed Central

    Girhard, Marco; Machida, Kazuhiro; Itoh, Masashi; Schmid, Rolf D; Arisawa, Akira; Urlacher, Vlada B

    2009-01-01

    Background (+)-Nootkatone (4) is a high added-value compound found in grapefruit juice. Allylic oxidation of the sesquiterpene (+)-valencene (1) provides an attractive route to this sought-after flavoring. So far, chemical methods to produce (+)-nootkatone (4) from (+)-valencene (1) involve unsafe toxic compounds, whereas several biotechnological approaches applied yield large amounts of undesirable byproducts. In the present work 125 cytochrome P450 enzymes from bacteria were tested for regioselective oxidation of (+)-valencene (1) at allylic C2-position to produce (+)-nootkatone (4) via cis- (2) or trans-nootkatol (3). The P450 activity was supported by the co-expression of putidaredoxin reductase (PdR) and putidaredoxin (Pdx) from Pseudomonas putida in Escherichia coli. Results Addressing the whole-cell system, the cytochrome CYP109B1 from Bacillus subtilis was found to catalyze the oxidation of (+)-valencene (1) yielding nootkatol (2 and 3) and (+)-nootkatone (4). However, when the in vivo biooxidation of (+)-valencene (1) with CYP109B1 was carried out in an aqueous milieu, a number of undesired multi-oxygenated products has also been observed accounting for approximately 35% of the total product. The formation of these byproducts was significantly reduced when aqueous-organic two-liquid-phase systems with four water immiscible organic solvents – isooctane, n-octane, dodecane or hexadecane – were set up, resulting in accumulation of nootkatol (2 and 3) and (+)-nootkatone (4) of up to 97% of the total product. The best productivity of 120 mg l-1 of desired products was achieved within 8 h in the system comprising 10% dodecane. Conclusion This study demonstrates that the identification of new P450s capable of producing valuable compounds can basically be achieved by screening of recombinant P450 libraries. The biphasic reaction system described in this work presents an attractive way for the production of (+)-nootkatone (4), as it is safe and can easily be controlled and scaled up. PMID:19591681

  18. ABIOTIC TRANSFORMATIONS OF TOXIC ORGANIC CHEMICALS IN THE LIQUID PHASE AND SEDIMENTS

    EPA Science Inventory

    Analyses of selected groundwater databases provide insight into the abiotic reaction conditions that occur in subsurface ecosystems. With this information it is possible to impose boundaries on the activity of selected chemical species in porous media and narrow the ranges of rea...

  19. Solid/Liquid phase diagram of the ammonium sulfate/succinic acid/water system.

    PubMed

    Pearson, Christian S; Beyer, Keith D

    2015-05-14

    We have studied the low-temperature phase diagram and water activities of the ammonium sulfate/succinic acid/water system using differential scanning calorimetry and infrared spectroscopy of thin films. Using the results from our experiments, we have mapped the solid/liquid ternary phase diagram, determined the water activities based on the freezing point depression, and determined the ice/succinic acid phase boundary as well as the ternary eutectic composition and temperature. We also compared our results to the predictions of the extended AIM aerosol thermodynamics model (E-AIM) and found good agreement for the ice melting points in the ice primary phase field of this system; however, differences were found with respect to succinic acid solubility temperatures. We also compared the results of this study with those of previous studies that we have published on ammonium sulfate/dicarboxylic acid/water systems. PMID:25431860

  20. LIQUID PHASE OXIDATION OF THIOPHENOL AND INDENE BY t-BUTYL HYDROPEROXIDE AND OXYGEN

    Microsoft Academic Search

    George W. Mushrush; John M. Watkinsa; Robert N. Hazlett; Dennis R. Hardy; Harold G. Eaton

    1988-01-01

    The tert-butyl hydroperoxide (tBHP) or oxygen initiated oxidation of thiophenol in the presence of the active olefin indene was examined in benzene at 120C. The reaction is kinetically complex, but it was possible to relate the product distribution to a few competing reactions. The product mix was determined for several reaction time periods. The product slate was similar for all

  1. Improved control of composition and electrical properties of liquid phase epitaxial (CdHg)Te layers

    Microsoft Academic Search

    M. G. Astles; N. Shaw; G. Blackmore; R. S. Hall

    1992-01-01

    Excellent compositional reproducibility, x value, and thickness are presently shown to be obtainable through the use of powdered HgTe as a source of Hg in an LPE growth sliding boat for Cd(x)Hg(1-x)Te production from Te-rich solutions at 460 C. SIMS analysis indicates that the In of the composition is 100-percent electrically active after Hg-rich annealing; the In dopant does not

  2. Preparation of Niobium-Doped Titanium Oxide Film by Liquid Phase Deposition

    Microsoft Academic Search

    Ming-Kwei Lee; Chung-Min Shih; Shih-Chang Fang; Hwei-Fu Tu; Chen-Lin Ho

    2007-01-01

    Niobium-doped amorphous titanium oxide film can be deposited on a Corning glass substrate using a mixture of ammonium hexafluorotitanate, boric acid, niobium oxide and ammonium hydrogen fluoride aqueous solutions. After thermal annealing, the nanocrystallite niobium-doped titanium oxide film can be obtained. The smaller crystallite size of nanocrystallite niobium-doped titanium oxide than that of undoped-titanium oxide benefits the catalytic activity for

  3. Biosorption of model pollutants in liquid phase on raw and modified rice husks

    NASA Astrophysics Data System (ADS)

    Toniazzo, L.; Fierro, V.; Braghiroli, F.; Amaral, G.; Celzard, A.

    2013-03-01

    We studied the application of rice husk (RH) as a biosorbent and we demonstrated that it can be employed for the treatment of dyeing wastewater streams. RH was obtained from Nile Delta (Egypt) and it was used as received, or after a chemical treatment using HNO3 or NaOH, or after conversion into activated carbon (RH-AC) using H3PO4 as activating agent. A commercial activated carbon GAC 830 provided by NORIT was also tested for comparison purposes. These materials were evaluated by adsorption of methylene blue (MB) with an initial concentration of 20 ppm in an aqueous solution at 30°C. The results showed that alkali-treated and RH-AC were the best sorbents. They got a nearly complete MB removal from water and they had better performance than GAC 830. Therefore, the use of RH for pollutant removal makes this method an environment-friendly option and an economically feasible alternative to treat industrial effluents.

  4. The CPA Equation of State and an Activity Coefficient Model for Accurate Molar Enthalpy Calculations of Mixtures with Carbon Dioxide and Water/Brine

    E-print Network

    P. C. Myint; Y. Hao; A. Firoozabadi

    2015-04-20

    Thermodynamic property calculations of mixtures containing carbon dioxide (CO$_2$) and water, including brines, are essential in theoretical models of many natural and industrial processes. The properties of greatest practical interest are density, solubility, and enthalpy. Many models for density and solubility calculations have been presented in the literature, but there exists only one study, by Spycher and Pruess, that has compared theoretical molar enthalpy predictions with experimental data. In this report, we recommend two different models for enthalpy calculations: the CPA equation of state by Li and Firoozabadi, and the CO$_2$ activity coefficient model by Duan and Sun. We show that the CPA equation of state, which has been demonstrated to provide good agreement with density and solubility data, also accurately calculates molar enthalpies of pure CO$_2$, pure water, and both CO$_2$-rich and aqueous (H$_2$O-rich) mixtures of the two species. It is applicable to a wider range of conditions than the Spycher and Pruess model. In aqueous sodium chloride (NaCl) mixtures, we show that Duan and Sun's model yields accurate results for the partial molar enthalpy of CO$_2$. It can be combined with another model for the brine enthalpy to calculate the molar enthalpy of H$_2$O-CO$_2$-NaCl mixtures. We conclude by explaining how the CPA equation of state may be modified to further improve agreement with experiments. This generalized CPA is the basis of our future work on this topic.

  5. In situ growth of capping-free magnetic iron oxide nanoparticles on liquid-phase exfoliated graphene

    NASA Astrophysics Data System (ADS)

    Tsoufis, T.; Syrgiannis, Z.; Akhtar, N.; Prato, M.; Katsaros, F.; Sideratou, Z.; Kouloumpis, A.; Gournis, D.; Rudolf, P.

    2015-05-01

    We report a facile approach for the in situ synthesis of very small iron oxide nanoparticles on the surface of high-quality graphene sheets. Our synthetic strategy involved the direct, liquid-phase exfoliation of highly crystalline graphite (avoiding any oxidation treatment) and the subsequent chemical functionalization of the graphene sheets via the well-established 1,3-dipolar cycloaddition reaction. The resulting graphene derivatives were employed for the immobilization of the nanoparticle precursor (Fe cations) at the introduced organic groups by a modified wet-impregnation method, followed by interaction with acetic acid vapours. The final graphene-iron oxide hybrid material was achieved by heating (calcination) in an inert atmosphere. Characterization by X-ray diffraction, transmission electron and atomic force microscopy, Raman and X-ray photoelectron spectroscopy gave evidence for the formation of rather small (<12 nm), spherical, magnetite-rich nanoparticles which were evenly distributed on the surface of few-layer (<1.2 nm thick) graphene. Due to the presence of the iron oxide nanoparticles, the hybrid material showed a superparamagnetic behaviour at room temperature.We report a facile approach for the in situ synthesis of very small iron oxide nanoparticles on the surface of high-quality graphene sheets. Our synthetic strategy involved the direct, liquid-phase exfoliation of highly crystalline graphite (avoiding any oxidation treatment) and the subsequent chemical functionalization of the graphene sheets via the well-established 1,3-dipolar cycloaddition reaction. The resulting graphene derivatives were employed for the immobilization of the nanoparticle precursor (Fe cations) at the introduced organic groups by a modified wet-impregnation method, followed by interaction with acetic acid vapours. The final graphene-iron oxide hybrid material was achieved by heating (calcination) in an inert atmosphere. Characterization by X-ray diffraction, transmission electron and atomic force microscopy, Raman and X-ray photoelectron spectroscopy gave evidence for the formation of rather small (<12 nm), spherical, magnetite-rich nanoparticles which were evenly distributed on the surface of few-layer (<1.2 nm thick) graphene. Due to the presence of the iron oxide nanoparticles, the hybrid material showed a superparamagnetic behaviour at room temperature. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr00765h

  6. In situ evaluation of supersolidus liquid phase sintering phenomena of stainless steel 316L: Densification and distortion

    NASA Astrophysics Data System (ADS)

    Bollina, Ravi

    Supersolidus liquid phase sintering (SLPS) is a variant of liquid phase sintering. In SLPS, prealloyed powders are heated between the solidus and liquidus temperature of the alloy. This thesis focuses on processing of stainless steel 316L via SLPS by adding boron. Various amounts of boron were added to study the effect of boron on densification and distortion. The sintering window for water atomized 316L with 0.2% boron ranges from 1430 to 1435°C and 1225 to 1245°C for water atomized 316L with 0.8% boron. The rate of change of liquid content with temperature dVL/dt decreases from 1.5%/°C to 0.1%/°C for in increase in boron content from 0 to 0.8%, giving a wider range and better control during sintering. Further; effect of boron on mechanical properties and corrosion properties was researched. It was possible to achieve tensile strength of 476+/-21 MPa and an yield strength of 250+/-5 MPa with an elongation of 15+/-2 % in water atomized 316L with 0.8% boron. Fracture analysis indicates the presence of a brittle boride phase along the grain boundary causing intergranular fracture resulting in poor ductility. The crux of this thesis discusses the evolution of apparent viscosity and its relation to the microstructure. Beam bending viscometry was successfully used to evaluate the in situ apparent viscosity evolution of water atomized 316L with 0.2 and 0.8% boron additions. The apparent viscosity drops from 174 GPa.s at 1200°C to 4 GPa.s at 1275°C with increasing fractional liquid coverage in the water atomized 316L with 0.8% boron. The apparent viscosity calculated from bending beam and was used as an input into a finite element model (FEM) derived from constitutive equations and gives an excellent, fit between simulation and experiment. The densification behavior of boron doped stainless steel was modelled using Master Sintering Curve (MSC) (based on work of sintering) for the first time. It is proven that MSC can be used to identify change in densification rate upon liquid formation during SLPS.

  7. Plasmas in Multiphase Media: Bubble Enhanced Discharges in Liquids and Plasma/Liquid Phase Boundaries

    SciTech Connect

    Kushner, Mark Jay [University of Michigan] [University of Michigan

    2014-07-10

    In this research project, the interaction of atmospheric pressure plasmas with multi-phase media was computationally investigated. Multi-phase media includes liquids, particles, complex materials and porous surfaces. Although this investigation addressed fundamental plasma transport and chemical processes, the outcomes directly and beneficially affected applications including biotechnology, medicine and environmental remediation (e.g., water purification). During this project, we made advances in our understanding of the interaction of atmospheric pressure plasmas in the form of dielectric barrier discharges and plasma jets with organic materials and liquids. We also made advances in our ability to use computer modeling to represent these complex processes. We determined the method that atmospheric pressure plasmas flow along solid and liquid surfaces, and through endoscopic like tubes, deliver optical and high energy ion activation energy to organic and liquid surfaces, and produce reactivity in thin liquid layers, as might cover a wound. We determined the mechanisms whereby plasmas can deliver activation energy to the inside of liquids by sustaining plasmas in bubbles. These findings are important to the advancement of new technology areas such as plasma medicine

  8. New mesoporous perovskite ZnTiO 3 and its excellent catalytic activity in liquid phase organic transformations

    Microsoft Academic Search

    Nabanita Pal; Manidipa Paul; Asim Bhaumik

    2011-01-01

    A new mesoporous perovskite ZnTiO3 material has been synthesized by the evaporation-induced self-assembly (EISA) method using non-ionic surfactant Pluronic P123 as template. After calcination of the dried gel of equimolar concentrations of Zn(II) and Ti(IV) at 673K, a new perovskite mesophase of ZnTiO3 (MZT-11) formed, having highly crystalline cubic ZnTiO3 pore wall. Interestingly, in the absence of P123 but otherwise

  9. Note on the effect of activity coefficients on the NMR association constants for the 2,4-dinitrotoluene—diphenylamine system. The Qureshi—Varshney—Kamoonpuri equation. Possible role of hydrogen bonding.

    NASA Astrophysics Data System (ADS)

    Qureshi, Pushkin M.; Varshney, Rishi K.; Kamoonpuri, S. Iqbal M.

    1989-01-01

    The NMR studies of the charge transfer complex between 2,4-dinitrotoluene and diphenylamine in CCl 4 are reinvestigated. The proposed QURESHI- VARSHNEY- KAMOONPURI equation shows that activity coefficients have a profound effect on the NMR association constants. The possibility of hydrogen bonding in the system has also been considered.

  10. Liquid phase Fischer-Tropsch (II) demonstration in the LaPorte Alternative Fuels Development Unit. Volume 1/2, Main Report. Final report

    SciTech Connect

    Bhatt, B.L.

    1995-09-01

    This report presents results from a demonstration of Liquid Phase Fischer-Tropsch (LPFT) technology in DOE`s Alternative Fuels Development Unit (AFDU) at LaPorte, Texas. The run was conducted in a bubble column at the AFDU in May--June 1994. The 10-day run demonstrated a very high level of reactor productivity for LPFT, more than five times the previously demonstrated productivity. The productivity was constrained by mass transfer limitations, perhaps due to slurry thickening as a result of carbon formation on the catalyst. With a cobalt catalyst or an improved iron catalyst, if the carbon formation can be avoided, there is significant room for further improvements. The reactor was operated with 0.7 H{sub 2}/CO synthesis gas in the range of 2400--11700 sl/hr-kg Fe, 175--750 psig and 270--300C. The inlet gas velocity ranged from 0.19 to 0.36 ft/sec. The demonstration was conducted at a pilot scale of 5 T/D. Catalyst activation with CO/N{sub 2} proceeded well. Initial catalyst activity was close to the expectations from the CAER autoclave runs. CO conversion of about 85% was obtained at the baseline condition. The catalyst also showed good water-gas shift activity and a low {alpha}. At high productivity conditions, reactor productivity of 136 grams of HC/hr -- liter of slurry volume was demonstrated, which was within the target of 120--150. However, mass transfer limitations were observed at these conditions. To alleviate these limitations and prevent excessive thickening, the slurry was diluted during the run. This enabled operations under kinetic control later in the run. But, the dilution resulted in lower conversion and reactor productivity. A new reactor internal heat exchanger, installed for high productivity conditions, performed well above design,and the system never limited the performance. The control can expected, the reactor temperature control needed manual intervention. The control can be improved by realigning the utility oil system.

  11. Partial Transient Liquid-Phase Bonding, Part II: A Filtering Routine for Determining All Possible Interlayer Combinations

    NASA Astrophysics Data System (ADS)

    Cook, Grant O.; Sorensen, Carl D.

    2013-12-01

    Partial transient liquid-phase (PTLP) bonding is currently an esoteric joining process with limited applications. However, it has preferable advantages compared with typical joining techniques and is the best joining technique for certain applications. Specifically, it can bond hard-to-join materials as well as dissimilar material types, and bonding is performed at comparatively low temperatures. Part of the difficulty in applying PTLP bonding is finding suitable interlayer combinations (ICs). A novel interlayer selection procedure has been developed to facilitate the identification of ICs that will create successful PTLP bonds and is explained in a companion article. An integral part of the selection procedure is a filtering routine that identifies all possible ICs for a given application. This routine utilizes a set of customizable parameters that are based on key characteristics of PTLP bonding. These parameters include important design considerations such as bonding temperature, target remelting temperature, bond solid type, and interlayer thicknesses. The output from this routine provides a detailed view of each candidate IC along with a broad view of the entire candidate set, greatly facilitating the selection of ideal ICs. This routine provides a new perspective on the PTLP bonding process. In addition, the use of this routine, by way of the accompanying selection procedure, will expand PTLP bonding as a viable joining process.

  12. In situ growth of capping-free magnetic iron oxide nanoparticles on liquid-phase exfoliated graphene.

    PubMed

    Tsoufis, T; Syrgiannis, Z; Akhtar, N; Prato, M; Katsaros, F; Sideratou, Z; Kouloumpis, A; Gournis, D; Rudolf, P

    2015-05-01

    We report a facile approach for the in situ synthesis of very small iron oxide nanoparticles on the surface of high-quality graphene sheets. Our synthetic strategy involved the direct, liquid-phase exfoliation of highly crystalline graphite (avoiding any oxidation treatment) and the subsequent chemical functionalization of the graphene sheets via the well-established 1,3-dipolar cycloaddition reaction. The resulting graphene derivatives were employed for the immobilization of the nanoparticle precursor (Fe cations) at the introduced organic groups by a modified wet-impregnation method, followed by interaction with acetic acid vapours. The final graphene-iron oxide hybrid material was achieved by heating (calcination) in an inert atmosphere. Characterization by X-ray diffraction, transmission electron and atomic force microscopy, Raman and X-ray photoelectron spectroscopy gave evidence for the formation of rather small (<12 nm), spherical, magnetite-rich nanoparticles which were evenly distributed on the surface of few-layer (<1.2 nm thick) graphene. Due to the presence of the iron oxide nanoparticles, the hybrid material showed a superparamagnetic behaviour at room temperature. PMID:25920624

  13. Hollow-fiber liquid-phase microextraction for the determination of natural and synthetic estrogens in milk samples.

    PubMed

    Socas-Rodríguez, Bárbara; Asensio-Ramos, María; Hernández-Borges, Javier; Rodríguez-Delgado, Miguel Ángel

    2013-10-25

    In this work, a group of nine estrogens, four of them being natural (estriol, 17?-estradiol, 17?-estradiol and estrone), four being synthetic (17?-ethynylestradiol, diethylstibestrol, dienestrol and hexestrol) and one metabolite (2-hydroxyestradiol) have been extracted and preconcentrated from milk samples with different fat content (whole, semi-skimmed and skimmed). After protein precipitation with acetonitrile containing acetic acid, evaporation of the supernatant and reconstitution of the residue in water, hollow-fiber liquid-phase microextraction (HF-LPME) using 1-octanol as extraction solvent was applied to further preconcentrate the analytes. Separation, determination and quantification were achieved by high-performance liquid chromatography coupled to a diode array detector and a fluorescence detector set in series. Deproteinization conditions, as well as parameters affecting the extraction efficiency in HF-LPME (pH of the sample, ionic strength, extraction time, stirring speed, temperature and desorption conditions) were investigated and optimized. Calibration, precision and accuracy studies were carried out to validate the methodology in different types of milk providing LODs in the low ?g/L range. PMID:23746643

  14. Liquid-Phase Synthesis of 2'-Methyl-RNA on a Homostar Support through Organic-Solvent Nanofiltration.

    PubMed

    Gaffney, Piers R J; Kim, Jeong F; Valtcheva, Irina B; Williams, Glynn D; Anson, Mike S; Buswell, Andrew M; Livingston, Andrew G

    2015-06-22

    Due to the discovery of RNAi, oligonucleotides (oligos) have re-emerged as a major pharmaceutical target that may soon be required in ton quantities. However, it is questionable whether solid-phase oligo synthesis (SPOS) methods can provide a scalable synthesis. Liquid-phase oligo synthesis (LPOS) is intrinsically scalable and amenable to standard industrial batch synthesis techniques. However, most reported LPOS strategies rely upon at least one precipitation per chain extension cycle to separate the growing oligonucleotide from reaction debris. Precipitation can be difficult to develop and control on an industrial scale and, because many precipitations would be required to prepare a therapeutic oligonucleotide, we contend that this approach is not viable for large-scale industrial preparation. We are developing an LPOS synthetic strategy for 2'-methyl RNA phosphorothioate that is more amenable to standard batch production techniques, using organic solvent nanofiltration (OSN) as the critical scalable separation technology. We report the first LPOS-OSN preparation of a 2'-Me RNA phosphorothioate 9-mer, using commercial phosphoramidite monomers, and monitoring all reactions by HPLC, (31) P?NMR spectroscopy and MS. PMID:26012874

  15. Liquid phase deposited titania coating to enable in vitro apatite formation on Ti6Al4V alloy.

    PubMed

    Hayakawa, Satoshi; Masuda, Yoshitake; Okamoto, Keigo; Shirosaki, Yuki; Kato, Kazumi; Osaka, Akiyoshi

    2014-02-01

    A recently developed "GRAPE(®) technology" provides titanium or titanium alloy implants with spontaneous apatite-forming ability in vitro, which requires properly designed gaps and optimum heat treatment in air. In this study, titanium alloy and commercially pure (cp) titanium substrates were thermally oxidized in air before aligning pairs of specimens in the GRAPE(®) set-up, i.e., titanium alloy and cp titanium substrates were aligned parallel to each other with optimum gap width (spatial design). A liquid phase deposition (LPD) technique was employed for titania coatings on titanium alloy substrate. Then, they were soaked in Kokubo's simulated body fluid (SBF, pH 7.4, 36.5 °C) for 7 days to confirm the in vitro apatite formation on the substrates under the specific spatial design. Anatase-type titania coatings fabricated by using LPD technique led to the deposition of apatite particles within 7 days and showed apatite X-ray diffraction. On the other hand, thermally oxidized titanium alloy substrate in air and non-treated specimens did not show any apatite X-ray diffraction. These results indicated that the heterogeneous nucleation of apatite induced on anatase-type titania coating prepared by LPD technique when it was aligned parallel to thermally oxidized cp titanium substrate with optimum gap width. PMID:24165799

  16. Determination at low ppm levels of dithiocarbamate residues in foodstuff by vapour phase-liquid phase microextraction-infrared spectroscopy.

    PubMed

    Gonzálvez, Ana; Garrigues, Salvador; Armenta, Sergio; de la Guardia, Miguel

    2011-03-01

    A methodology based on the vapour phase (VP) generation of carbon disulphide from non-volatile dithiocarbamate compounds has been developed for determination of pesticide residues in foodstuff at low ppm levels. The method involves a selective reaction combined with liquid phase microextraction (LPME) and transmission infrared measurements. The use of a home made transmission cell improved the detection limits (LOD) compared to the use of attenuated total reflectance measurements by a factor of approximately 80. Using the most appropriate experimental conditions for the CS(2) generation and LPME preconcentration, the precision of the methodology, expressed as the relative standard deviation (RSD), was of the order of 3.1% and the absolute LOD was 0.3 ?g dithiocarbamate, which corresponds to 60-120 ?g kg(-1), for a sample mass ranging from 2.5 to 5 g. The usefulness of the methodology has been evidenced by the determination of mancozeb residues in strawberries, lettuce and corn samples at concentrations between 1 and 5 mg kg(-1), where the VP-LPME IR provided results comparable with those obtained by a head space gas chromatography mass spectrometry reference procedure. PMID:21334485

  17. Liquid-phase-deposited silicon oxide film as a mask for single-sided texturing of monocrystalline Si wafers.

    PubMed

    Lin, Tao; Jiang, Kun; Zhou, Bo-Xuan; Xu, Su-Fan; Cai, Wen-Bin

    2014-01-22

    A silicon oxide film doped with fluorine was grown on a (100)-oriented Si wafer through liquid-phase deposition (LPD) as a protective mask of the wafer's rear side in order to chemically texture the wafer's unprotected front side in a basic etching bath, which is a new process in solar-cell manufacturing. The growth rate of the LPD-SiO2 film increased monotonically with an increase of the deposition temperature up to 60 °C for a given precursor solution. Field-emission scanning electron microscopy (FE-SEM) indicates that a pyramidal surface texture forms on the front side in the chemical texturing bath, whereas the underlying Si surface on the rear side remains intact. As a result, the average reflectivity for incident light over 450-850 nm is decreased to 11.1% on the front side, and a 5.8 ?m thick Si surface on the rear side is saved per wafer. The all-wet process involved in this single-sided texturing is promising for the mass production of thinner and higher-efficiency Si-based solar cells because of its simplicity and lower cost. PMID:24372321

  18. Stabilizer effects on the synthesis of gold-containing microparticles. Application to the liquid phase oxidation of glycerol.

    PubMed

    Gil, Sonia; Jiménez-Borja, Carmen; Martin-Campo, J; Romero, Amaya; Valverde, José Luis; Sánchez-Silva, Luz

    2014-10-01

    Gold-containing poly(urea-formaldehyde) microparticles were prepared by the in situ polymerization method using a series of stabilization agents with different chemical nature. The effects of cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), polyvinyl pyrrolidone (PVP), polyvinyl alcohol (PVA) and tetrakis(hydroxymethyl)phosphonium chloride (THPC) on the morphology, the particle size of encapsulated gold, the gold particle size distribution and the encapsulation efficiency were investigated by using scanning electron microscopy, X-ray diffraction and atomic absorption analyses. The chemical nature of stabilizer had a marked influence on both the encapsulated gold particle size and the encapsulation efficiency. Both gold particle size and gold encapsulation efficiency increased when decreasing the stabilizer polarity number. All the microparticles here prepared were tested in the liquid phase selective oxidation of glycerol. The glycerol conversion increased and the glyceric acid selectivity decreased when decreasing gold particle sizes. Results showed that use of stabilizers with hydrophobic surfaces enhanced the selectivity to C3 products in the resulting catalysts. On the other hand, the use of stabilizers with hydrophilic surfaces increased the C-C bond cleavage products in the resulting catalysts. PMID:24996018

  19. Growth of Zn 3As 2 on GaAs by liquid phase epitaxy and their characterization

    NASA Astrophysics Data System (ADS)

    Nagarajan, M.; Sudhakar, S.; Lourdudoss, S.; Baskar, K.

    2011-01-01

    Zn 3As 2 epitaxial layers were grown on GaAs (1 0 0) substrates by liquid phase epitaxy (LPE) using Ga as the solvent. Zinc mole fraction in the growth melt was varied from 1.07×10 -2 to 6×10 -2. X-ray diffraction spectrum exhibits a sharp peak at 43.3° characteristic of Zn 3As 2 crystalline layer. The peak intensity increases with increase in zinc mole fraction in the growth melt. The compositions of the as-grown Zn 3As 2 layers were confirmed by energy dispersive X-ray (EDX) analysis. Surface morphology was studied using scanning electron microscopy (SEM) and the thickness of the epilayers was also determined. The Hall measurements at 300 K indicate that Zn 3As 2 epilayers are unintentionally p-doped. With an increase of zinc mole fraction in the growth melt, carrier concentration increases and carrier mobility decreases. Infrared optical absorption spectroscopy showed a sharp absorption edge at 1.0 eV corresponding to the reported band gap of Zn 3As 2.

  20. Optical and Structural Quality of GaAs Epilayers from Gallium, Bismuth Mixed Solvents by Liquid Phase Epitaxy

    NASA Astrophysics Data System (ADS)

    Saravanan, Shanmugam; Jeganathan, Kulandaivel; Arokiaraj, Jesudoss; Baskar, Krishnan; Ramasamy, Perumal; Jimbo, Takashi; Soga, Tetsuo; Umeno, Masayoshi

    1998-05-01

    Liquid phase epitaxy (LPE) of GaAs epilayers grown at 645°C was studied for different Bi compositions in Ga solvent . Mixed solvents such as Ga+Bi were used to improve GaAs epilayer quality. The grown layers were characterized by photoluminescence (PL) and etch pit density (EPD) measurements. The Bi composition was varied from 0 to 100% in Ga. Good quality epilayers were obtained for 100% Bi composition. PL investigations revealed that the epilayer grown using equal atomic percentage of Ga and Bi had good crystallinity, which is comparable with the 100%-Ga-grown epilayer. The PL measurements reveal that carbon inclusion in the epilayer grown using 50% Ga and 50% Bi solution is comparably less than other solvent compositions. The EPD was reduced to more than half order of magnitude when the solvent was changed from Ga to Bi. The EPD results of epilayers grown using mixed solvents are reported for the first time. The EPD of the GaAs epilayer grown using 50% Ga and 50% Bi solution is markedly reduced compared to the other Ga+Bi mixed solvents, and it is almost equal to the EPD of 100%-Bi-grown epilayers.

  1. The effect of liquid-phase sintering on the properties of Pr6O11-based ZnO varistors

    NASA Astrophysics Data System (ADS)

    Alles, Aldo B.; Burdick, Vernon L.

    1991-12-01

    Conventionally batched varistors in the ZnO-Co3O4-Pr6O11 system that were sintered at or above 1280 °C exhibited a sharp increase in the average breakdown voltage per grain boundary. In these samples, barrier heights and donor concentration values, derived from capacitance-voltage analysis, exhibited sharp changes at the same soaking temperature. At or above 1280 °C, grain growth in this system proceeds with the assistance of an eutectic liquid. The improvement of the distribution of Pr6O11, by precipitation of Pr(OH)3 during batching, resulted in varistors markedly more insensitive to firing temperature than conventionally batched ones. The presence of a liquid phase, at least during grain growth, results in an efficient distribution of grain boundary materials and dopants in general. Suitable chemisorbed gases along the grain boundaries are believed to be responsible for the formation of interface states. Segregated materials appeared to provide for enhanced transport of gaseous species along the grain boundaries. The need for the addition of oxides with large ionic-radius cations, i.e., varistor-forming oxides such as bismuth, barium, praseodymium, or lanthanum oxide, to varistor compositions is explained within this context.

  2. Liquid-phase silylation characterization of Shipley SPR500A-series resists using PRIME top surface imaging process

    NASA Astrophysics Data System (ADS)

    Arshak, Khalil I.; Mihov, Miroslav; Arshak, Arousian; McDonagh, Declan; Sutton, David; Newcomb, Simon; Kinsella, Thomas J.

    2003-03-01

    Top Surface Imaging (TSI) is a well-established technique used to improve resolution for optical, ultraviolet and electron-beam lithography. The Positive Resist Image by Dry Etching (PRIME) is an advanced lithographic process incorporating electron beam exposure, near UV flood exposure, silylation and dry development. In this paper, the liquid-phase silylation process step in PRIME with Shipley SPR500A-series resists has been experimentally investigated as the most critical part of the process. FT-IR spectroscopy, UV spectroscopy, SIM spectrometry and cross-sectional SEM and TEM were used to characterise the silylation process. Electron-beam exposure with dose in the range of 25-100?C/cm2 at 30KeV was used to crosslinks the resist. Results show that an e-beam dose of 50³C/cm2 was sufficient to prevent silylation in the crosslinked areas. Two bifunctional silylating agents, the cyclic Hexamethylcyclotrisilazane (HMCTS) and the linear Bis[Dimethylamino] dimethylsilane (B[DMA]DMS), were examined and found that they silylate SPR505A much more efficiently than the previously reported Hexamethylcyclotrisiloxane (HMCTSx). The silylation contrast of the PRIME process using HMCTS silylating agent and SPR505A resist was found to be 11:1. The obtained silylated profiles of 1mm lines/spaces gratings for Shipley SPR510A resist have almost vertical sidewalls resulting in very high contrast between the silylated and unsilylated parts of the resist.

  3. Synthesis of new phosphorus-containing (co)polyesters using solid-liquid phase transfer catalysis and product characterization.

    PubMed

    Iliescu, Smaranda; Augusti, Maite-Gyl; Fagadar-Cosma, Eugenia; Plesu, Nicoleta; Fagadar-Cosma, Gheorghe; Macarie, Lavinia; Popa, Adriana; Ilia, Gheorghe

    2012-01-01

    This paper is directed towards the development of safe, and thermally stable solid polymer electrolytes. Linear phosphorus-containing (co)polyesters are described, including their synthesis, thermal analysis, conductivity, and non-flammability. Polycondensation of phenylphosphonic dichloride (PPD) with poly(ethylene glycol) (PEG 12000) with and without bisphenol A (BA) was carried out using solid-liquid phase transfer catalysis. Potassium phosphate is used as base. Yields in the range of 85.0-88.0%, and inherent viscosities in the range of 0.32-0.58 dL/g were obtained. The polymers were characterized by gel permeation chromatography, FT-IR, (1)H- and (31)P-NMR spectroscopy and thermal analysis. Their flammability was investigated by measuring limiting oxygen index values. The polymers are flame retardants and begin to lose weight in the 190 °C-231 °C range. Solid phosphorus- containing (co)polyesters were complexed with lithium triflate and the resulting ionic conductivity was determined. Conductivities in the range of 10(-7)-10(-8) S cm(-1) were obtained. PMID:22850325

  4. Iron-histidine resonance raman band of deoxyheme proteins: effects of anharmonic coupling and glass-liquid phase transition

    PubMed Central

    Bitler, A; Stavrov, SS

    1999-01-01

    Weak anharmonic coupling of two soft molecular vibrations is shown to cause pronounced temperature dependence of the corresponding resonance Raman bands. The developed theory is used to interpret the temperature dependence of the iron-histidine band of deoxyheme proteins and model compounds. It is shown that anharmonic coupling of the iron-histidine and heme doming vibrations must cause pronounced broadening of the band, its asymmetry, and shift of its maximum to the red upon heating. It also can lead to a structured shape of this band at room temperature. Proper consideration of the anharmonic coupling allows simulation of the temperature dependence of the iron-histidine band shape of horse heart myoglobin in the temperature interval of 10-300 K, using the minimum number of necessary parameters. Analysis of this temperature dependence clearly shows that the iron-histidine band of deoxyheme proteins is sensitive to the glass-liquid phase transition in the protein hydration shell, which takes place at 160-190 K. PMID:10545375

  5. Reduced-Temperature Transient-Liquid-Phase Bonding of AluminaUsing a Ag-Cu-Based Brazing Alloy

    SciTech Connect

    Hong, Sung Moo; Glaeser, Andreas M.

    2005-12-19

    The mechanical properties and microstructural evolution ofmetal-ceramic bonds produced using a transient liquid phase (TLP) aredescribed. Alumina (Al2O3) was joined at 500 degrees C, 600 degrees C,and 700 degrees C using a multilayer In/Cusil-ABA (R) (commercialcopper-silver eutectic brazing alloy)/In interlayer. The introduction ofthin In cladding layers allows the system to bond at much lowertemperatures than those typically used for brazing with Cusil-ABA (R),thereby protecting temperature-sensitive components. After chemicalhomogenization, the interlayers retain an operating temperature rangesimilar to that of the brazed joints. TLP bonds made at 500 degrees C,600 degrees C, and 700 degrees C with holding times ranging from as lowas 1.5 h to 24 h had average fracture strengths above 220 MPa. Theeffects of bonding temperature and time on fracture strength aredescribed. Preliminary analysis of the interlayers shows that the Ag-Inor Cu-In intermetallic phases do not form. Considerations unique tosystems with two-phase core layers are discussed. Experiments usingsingle-crystal sapphire indicate rapid formation of a reaction layer at700 degrees C, suggesting the possibility of making strong bonds usinglower temperatures and/or shorter processing times.

  6. Analysis of oestrogenic compounds in dairy products by hollow-fibre liquid-phase microextraction coupled to liquid chromatography.

    PubMed

    Socas-Rodríguez, Bárbara; Asensio-Ramos, María; Hernández-Borges, Javier; Rodríguez-Delgado, Miguel Ángel

    2014-04-15

    In this work, the potential of a hollow-fibre liquid-phase microextraction (LPME)-based method has been studied and validated for the extraction of a group of nine oestrogenic compounds four of them being natural (oestriol, 17?-oestradiol, 17?-oestradiol and oestrone), four being synthetic (17?-ethynyloestradiol, diethylstilbestrol, dienestrol and hexestrol) and one metabolite (2-hydroxyoestradiol) in different dairy products (whole and skimmed natural yogurt, a probiotic yogurt-type drink and cheese). The methodology includes a prior protein precipitation with acidified acetonitrile for all samples and an additional defatting step with n-hexane for cheese, the matrix with the highest fat content. Later separation, determination and quantification were done by high-performance liquid chromatography coupled to a diode array detector and a fluorescence detector set in series. Calibration, sensitivity, precision and accuracy of the method were carried out in the selected matrices, providing good linearity, LODs in the low ?g/kg or ?g/L range, good precision and appropriate accuracy. PMID:24295713

  7. Saddle-like deformation in a dielectric elastomer actuator embedded with liquid-phase gallium-indium electrodes

    SciTech Connect

    Wissman, J., E-mail: jwissman@andrew.cmu.edu [Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Finkenauer, L. [Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Deseri, L. [DICAM, Department of Mechanical, Civil and Environmental Engineering, University of Trento, via Mesiano 77 38123 Trento (Italy); TMHRI-Department of Nanomedicine, The Methodist Hospital Research Institute, 6565 Fannin St., MS B-490 Houston, Texas 77030 (United States); Mechanics, Materials and Computing Center, CEE and ME-CIT, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Majidi, C. [Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Robotics Institute and Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States)

    2014-10-14

    We introduce a dielectric elastomer actuator (DEA) composed of liquid-phase Gallium-Indium (GaIn) alloy electrodes embedded between layers of poly(dimethylsiloxane) (PDMS) and examine its mechanics using a specialized elastic shell theory. Residual stresses in the dielectric and sealing layers of PDMS cause the DEA to deform into a saddle-like geometry (Gaussian curvature K<0). Applying voltage ? to the liquid metal electrodes induces electrostatic pressure (Maxwell stress) on the dielectric and relieves some of the residual stress. This reduces the longitudinal bending curvature and corresponding angle of deflection ?. Treating the elastomer as an incompressible, isotropic, NeoHookean solid, we develop a theory based on the principle of minimum potential energy to predict the principal curvatures as a function of ?. Based on this theory, we predict a dependency of ? on ? that is in strong agreement with experimental measurements performed on a GaIn-PDMS composite. By accurately modeling electromechanical coupling in a soft-matter DEA, this theory can inform improvements in design and fabrication.

  8. Evaluation of the Transient Liquid Phase (TLP) Bonding Process for Ti3Al-Based Honeycomb Core Sandwich Structure

    NASA Technical Reports Server (NTRS)

    Bird, R. Keith; Hoffman, Eric K.

    1998-01-01

    The suitability of using transient liquid phase (TLP) bonding to fabricate honeycomb core sandwich panels with Ti-14Al-21Nb (wt%) titanium aluminide (T3Al) face sheets for high-temperature hypersonic vehicle applications was evaluated. Three titanium alloy honeycomb cores and one Ti3Al alloy honeycomb core were investigated. Edgewise compression (EWC) and flatwise tension (FWT) tests on honeycomb core sandwich specimens and tensile tests of the face sheet material were conducted at temperatures ranging from room temperature to 1500 F. EWC tests indicated that the honeycomb cores and diffusion bonded joints were able to stabilize the face sheets up to and beyond the face sheet compressive yield strength for all temperatures investigated. The specimens with the T3Al honeycomb core produced the highest FWT strengths at temperatures above 1000 F. Tensile tests indicated that TLP processing conditions resulted in decreases in ductility of the Ti-14Al-21Nb face sheets. Microstructural examination showed that the side of the face sheets to which the filler metals had been applied was transformed from equiaxed alpha2 grains to coarse plates of alpha2 with intergranular Beta. Fractographic examination of the tensile specimens showed that this transformed region was dominated by brittle fracture.

  9. Spin-liquid phase in a spatially anisotropic frustrated antiferromagnet: A Schwinger boson mean-field approach

    NASA Astrophysics Data System (ADS)

    Merino, Jaime; Holt, Michael; Powell, Ben J.

    2014-06-01

    We explore the effect of the third-nearest neighbors on the magnetic properties of the Heisenberg model on an anisotropic triangular lattice. We obtain the phase diagram of the model using Schwinger boson mean-field theory. Competition between Néel, spiral, and collinear magnetically ordered phases is found as we vary the ratios of the nearest J1, next-nearest J2, and third-nearest J3 neighbor exchange couplings. A spin-liquid phase is stabilized between the spiral and collinear ordered states when J2/J1?1.8, for rather small J3/J1?0.1. The lowest-energy two-spinon dispersions relevant to neutron scattering experiments are analyzed and compared to semiclassical magnon dispersions finding significant differences in the spiral and collinear phases between the two approaches. The results are discussed in the context of the anisotropic triangular materials: Cs2CuCl4 and Cs2CuBr4 and layered organic materials, ?-(BEDT-TTF)2X, and Y[Pd(dmit)2]2.

  10. Quantitative single dilution liquid phase blocking ELISA for sero-monitoring of foot-and-mouth disease in India.

    PubMed

    Sharma, Gaurav Kumar; Mahajan, Sonalika; Matura, Rakesh; Subramaniam, Saravanan; Mohapatra, Jajati K; Pattnaik, Bramhadev

    2015-05-01

    Three of the seven serotypes of foot-and-mouth disease (FMD) virus are prevailing in India. A massive vaccination campaign is on to control and eradicate the disease from the country. However, FMD vaccines provide short term immunity, hence regular assessment of antibody level in the vaccinated herds is indispensible for the success of the control programme. The antibodies are quantitatively estimated, either by virus neutralization test or by end-point dilution liquid-phase-blocking ELISA (LPBE). Millions of cattle and buffalo in the country are now systematically vaccinated, and thousands of serum samples are routinely screened in the country for estimation of herd immunity against FMDV serotypes O, A and Asia1. Testing such a large number of serum samples within limited a period of time by the conventional end point dilution method of LPBE requires lots of man power, and biological reagents. A more economical high throughput single dilution LPBE (SdLPBE) assay was optimized and validated for quantitative estimation of antibody levels against the three FMD virus serotypes. The assay was thoroughly validated against LPBE method before adopting it for country-wide use. The biological reagents used in the assay were prepared in thermo-stable form to enable transportation to the field level FMD diagnostic laboratories. PMID:25911541

  11. Picosecond dynamics of reactions in the liquid phase: studies of iodine photodissociation and development of new laser techniques

    SciTech Connect

    Berg, M.A.

    1985-09-01

    Iodine photodissociation and recombination was studied as a model for processes common to chemical reaction in the liquid phase. Picosecond transient absorption measurements from 1000 to 295 nm were used to monitor the dynamics in a variety of solvents. Most of the atoms which undergo geminate recombination were found to do so in less than or equal to 15 ps, in agreement with the results of existing molecular dynamics simulations. Vibrational relaxation times vary from approx.15 ps near the middle of the ground state well to approx.150 ps for complete relaxation to v = 0. The prediction of strong resonant vibrational energy transfer to chlorinated methane solvents was not supported, but some evidence for this mechanism was found for alkane solvents. Current theory is unable to explain the large variation (65 to 2700 ps) of the excited A'-state lifetime in various solvents. The 10-Hz amplified, synchronously-pumped dye laser which was used in these studies is described and characterized. SERS (Stimulated Electronic Raman Scattering) and difference frequency mixing were used in the generation of the infrared and far-infrared, respectively. 54 refs., 38 figs., 3 tabs. (WRF)

  12. Preparation of few-layer bismuth selenide by liquid-phase-exfoliation and its optical absorption properties.

    PubMed

    Sun, Liping; Lin, Zhiqin; Peng, Jian; Weng, Jian; Huang, Yizhong; Luo, Zhengqian

    2014-01-01

    Bismuth selenide (Bi2Se3), a new topological insulator, has attracted much attention in recent years owing to its relatively simple band structure and large bulk band gap. Compared to bulk, few-layer Bi2Se3 is recently considered as a highly promising material. Here, we use a liquid-phase exfoliation method to prepare few-layer Bi2Se3 in N-methyl-2-pyrrolidone or chitosan acetic solution. The resulted few-layer Bi2Se3 dispersion demonstrates an interesting absorption in the visible light region, which is different from bulk Bi2Se3 without any absorption in this region. The absorption spectrum of few-layer Bi2Se3 depends on its size and layer number. At the same time, the nonlinear and saturable absorption of few-layer Bi2Se3 thin film in near infrared is also characterized well and further exploited to generate laser pulses by a passive Q-switching technique. Stable Q-switched operation is achieved with a lower pump threshold of 9.3?mW at 974?nm, pulse energy of 39.8?nJ and a wide range of pulse-repetition-rate from 6.2 to 40.1?kHz. Therefore, the few-layer Bi2Se3 may excite a potential applications in laser photonics and optoelectronic devices. PMID:24762534

  13. Preparation of Few-Layer Bismuth Selenide by Liquid-Phase-Exfoliation and Its Optical Absorption Properties

    PubMed Central

    Sun, Liping; Lin, Zhiqin; Peng, Jian; Weng, Jian; Huang, Yizhong; Luo, Zhengqian

    2014-01-01

    Bismuth selenide (Bi2Se3), a new topological insulator, has attracted much attention in recent years owing to its relatively simple band structure and large bulk band gap. Compared to bulk, few-layer Bi2Se3 is recently considered as a highly promising material. Here, we use a liquid-phase exfoliation method to prepare few-layer Bi2Se3 in N-methyl-2-pyrrolidone or chitosan acetic solution. The resulted few-layer Bi2Se3 dispersion demonstrates an interesting absorption in the visible light region, which is different from bulk Bi2Se3 without any absorption in this region. The absorption spectrum of few-layer Bi2Se3 depends on its size and layer number. At the same time, the nonlinear and saturable absorption of few-layer Bi2Se3 thin film in near infrared is also characterized well and further exploited to generate laser pulses by a passive Q-switching technique. Stable Q-switched operation is achieved with a lower pump threshold of 9.3?mW at 974?nm, pulse energy of 39.8?nJ and a wide range of pulse-repetition-rate from 6.2 to 40.1?kHz. Therefore, the few-layer Bi2Se3 may excite a potential applications in laser photonics and optoelectronic devices. PMID:24762534

  14. Determination of iodate in waters by cuvetteless UV-vis micro-spectrophotometry after liquid-phase microextraction.

    PubMed

    Pena-Pereira, Francisco; Senra-Ferreiro, Sonia; Lavilla, Isela; Bendicho, Carlos

    2010-04-15

    The combination of liquid-phase microextraction and microvolume UV-vis spectrophotometry has been applied to the determination of iodate in natural water samples. The method is based on the reduction of iodate into vapor iodine and extraction of this volatile onto a single drop of N,N'-dimethylformamide. The following derivatization reaction was employed: Optimum conditions employed for iodate determination were as follows: 2.5 microL N,N'-dimethylformamide exposed to the headspace of a 10 mL acidic (HCl 0.2 mol L(-1)) aqueous solution stirred at 1400 rpm for 7 min after addition of 1 mL of KI 10(-3)mol L(-1) for in situ iodine generation. The limit of detection was determined as 1.1 microg L(-1). The repeatability, expressed as relative standard deviation, was 4.2% (n=6). A large preconcentration factor (i.e. 396) was obtained in only 7 min. PMID:20188973

  15. Determination of substituted benzenes in water samples by fiber-in-tube liquid phase microextraction coupled with gas chromatography.

    PubMed

    Wang, Jun-Xia; Jiang, Dong-Qing; Yan, Xiu-Ping

    2006-01-15

    A method for determination of toluene, ethylbenzene, p-xylene, o-xylene, 1,3,5-trimethylbenzene and 1,2,4-trimethylbenzene in water samples was developed by a fiber-in-tube liquid phase microextraction technique (fiber-in-tube LPME) coupled with GC-flame ionization detector (FID). The method used a tube packed with polytetrafluoroethylene (PTFE) fibers as an extraction medium, improving the stableness of the solvent and the performance of extraction. Certain amounts of curled PTFE fibers were packed into a section of PTFE tube. Because the fibers were curled, they formed network structure in the tube. The fiber packed tube was firstly immersed into organic solvent to be filled with organic solvent and then was exposing to an aqueous solution to extract the target compounds. The extract was then retracted by a conventional GC microsyringe and analyzed by GC-FID. Extraction of the analytes in 8 ml aqueous solution for 15 min yielded enrichment factors of 224-361. The precision (R.S.D., n=5) was 3.6-8.1% for peak area. The limit of detection (LOD, S/N=3) for the six substituted benzenes were in the range of 0.3-5.0 microgl(-1). PMID:18970414

  16. Isopiestic Investigation of the Osmotic and Activity Coefficients of {yMgCl2 + (1 - y)MgSO4}(aq) and the Osmotic Coefficients of Na2SO4.MgSO4(aq) at 298.15 K

    SciTech Connect

    Miladinovic, J; Ninkovic, R; Todorovic, M; Rard, J A

    2007-06-06

    Isopiestic vapor pressure measurements were made for {l_brace}yMgCl{sub 2} + (1-y)MgSO{sub 4}{r_brace}(aq) solutions with MgCl{sub 2} ionic strength fractions of y = 0, 0.1997, 0.3989, 0.5992, 0.8008, and (1) at the temperature 298.15 K, using KCl(aq) as the reference standard. These measurements for the mixtures cover the ionic strength range I = 0.9794 to 9.4318 mol {center_dot} kg{sup -1}. In addition, isopiestic measurements were made with NaCl(aq) as reference standard for mixtures of {l_brace}xNa{sub 2}SO{sub 4} + (1-x)MgSO{sub 4}{r_brace}(aq) with the molality fraction x = 0.50000 that correspond to solutions of the evaporite mineral bloedite (astrakanite), Na{sub 2}Mg(SO{sub 4}){sub 2} {center_dot} 4H{sub 2}O(cr). The total molalities, m{sub T} = m(Na{sub 2}SO{sub 4}) + m(MgSO{sub 4}), range from m{sub T} = 1.4479 to 4.4312 mol {center_dot} kg{sup -1} (I = 5.0677 to 15.509 mol {center_dot} kg{sup -1}), where the uppermost concentration is the highest oversaturation molality that could be achieved by isothermal evaporation of the solvent at 298.15 K. The parameters of an extended ion-interaction (Pitzer) model for MgCl2(aq) at 298.15 K, which were required for an analysis of the {l_brace}yMgCl{sub 2} + (1-y)MgSO{sub 4}{r_brace}(aq) mixture results, were evaluated up to I = 12.025 mol {center_dot} kg{sup -1} from published isopiestic data together with the six new osmotic coefficients obtained in this study. Osmotic coefficients of {l_brace}yMgCl{sub 2} + (1-y)MgSO{sub 4}{r_brace}(aq) solutions from the present study, along with critically-assessed values from previous studies, were used to evaluate the mixing parameters of the extended ion-interaction model.

  17. ESR evidence for 2 coexisting liquid phases in deeply supercooled bulk water

    PubMed Central

    Banerjee, D.; Bhat, S. N.; Bhat, S. V.; Leporini, D.

    2009-01-01

    Using electron spin resonance spectroscopy (ESR), we measure the rotational mobility of probe molecules highly diluted in deeply supercooled bulk water and negligibly constrained by the possible ice fraction. The mobility increases above the putative glass transition temperature of water, Tg = 136 K, and smoothly connects to the thermodynamically stable region by traversing the so called “no man's land” (the range 150–235 K), where it is believed that the homogeneous nucleation of ice suppresses the liquid water. Two coexisting fractions of the probe molecules are evidenced. The 2 fractions exhibit different mobility and fragility; the slower one is thermally activated (low fragility) and is larger at low temperatures below a fragile-to-strong dynamic cross-over at ?225 K. The reorientation of the probe molecules decouples from the viscosity below ?225 K. The translational diffusion of water exhibits a corresponding decoupling at the same temperature [Chen S-H, et al. (2006) The violation of the Stokes–Einstein relation in supercooled water. Proc Natl Acad Sci USA 103:12974–12978]. The present findings are consistent with key issues concerning both the statics and the dynamics of supercooled water, namely the large structural fluctuations [Poole PH, Sciortino F, Essmann U, Stanley HE (1992) Phase behavior of metastable water. Nature 360:324–328] and the fragile-to-strong dynamic cross-over at ?228 K [Ito K, Moynihan CT, Angell CA (1999) Thermodynamic determination of fragility in liquids and a fragile-to-strong liquid transition in water. Nature 398:492–494]. PMID:19556546

  18. Simultaneous determination of nine flavonoids in Polygonum hydropiper L. samples using nanomagnetic powder three-phase hollow fibre-based liquid-phase microextraction combined with ultrahigh performance liquid chromatography-mass spectrometry.

    PubMed

    Yang, Xian; Wang, Bo-Chu; Zhang, Xue; Yang, Shui-Ping; Li, Wei; Tang, Qian; Singh, Gurinder K

    2011-01-25

    A simple, inexpensive, and efficient nanomagnetic powder three-phase hollow fibre-based liquid-phase microextraction (HF-LPME) technique combined with ultrahigh performance liquid chromatography-mass spectrometry (UPLC-MS) was developed for the simultaneous analysis of nine flavonoids in Polygonum hydropiper L. samples. The final, optimised extraction conditions were as follows: an organic solvent of ethyl acetate, a donor phase of aqueous KH?PO? at pH 3.0, an acceptor phase of aqueous NaHCO? at pH 8.5, a stirring rate of 1000 rpm, and an extraction time of 50 min. Under these conditions, analyte calibration curves were all linear, with correlation coefficients ? 0.9994. The relative standard deviation for all analytes in intra-day (0.8-2.2%) and inter-day (1.7-3.5%) precision tests was well within the acceptable ranges, as were the limits of quantitation (LOQ < 0.054 ?g/L) and detection (LOD < 0.170 ?g/L). Recoveries for all standard compounds were between 95.17% and 99.82%, with a RSD of no more than 2.3%. Correlative analyses demonstrated that the physicochemical parameters of the compounds themselves also influenced the extraction efficiency. This technology proved to be rapid, sensitive, and reliable for the quality control of P. hydropiper L. samples. PMID:20880647

  19. Three-phase molecularly imprinted sol-gel based hollow fiber liquid-phase microextraction combined with liquid chromatography-tandem mass spectrometry for enrichment and selective determination of a tentative lung cancer biomarker.

    PubMed

    Moein, Mohammad Mahdi; Javanbakht, Mehran; Karimi, Mohammad; Akbari-Adergani, Behrouz; Abdel-Rehim, Mohamed

    2015-07-15

    In the present study, the modification of a polysulfone hollow fiber membrane with in situ molecularly imprinted sol-gel process (as a novel and one-step method) was prepared and investigated. 3-(propylmethacrylate)trimethoxysilane (3PMTMOS) as an inorganic precursor was used for preparation of molecularly imprinted sol-gel. The modified molecularly imprinted sol-gel hollow fiber membrane (MSHM) was used for the liquid-phase microextraction (LPME) of hippuric acid (HA) in human plasma and urine samples. MSHM as a selective, robust, and durable tool was used for at least 50 extractions without significant decrease in the extraction efficiency. The non-molecularly imprinted sol-gel hollow fiber membrane (NSHM) as blank hollow fiber membrane was prepared by the same process, only without HA. To achieve the best condition, influential parameters on the extraction efficiency were thoroughly investigated. The capability of this robust, green, and simple method for extraction of HA was successfully accomplished with LC/MS/MS. The limits of detection (LOD) and quantification (LOQ) in human plasma and urine samples were 0.3 and 1.0nmolL(-1), respectively. The standard calibration curves were obtained within the concentration range 1-2000nmolL(-1) for HA in human plasma and urine. The coefficients of determination (r(2)) were ?0.998. The obtained data exhibited recoveries were higher than 89% for the extraction of HA in human plasma and urine samples. PMID:26021850

  20. Phase equilibria and the growth of In 1-xGa xP by Peltier-induced liquid phase epitaxy

    NASA Astrophysics Data System (ADS)

    Lewis, Alvin

    1981-06-01

    A ternary liquidus cooling curve between the 850 and 800°C liquidus isotherms was experimentally determined to enable the growth of thick, constant composition, and lattice matched In 1- xGa xP on GaAs(100) by Peltier-induced Liquid Phase Epitaxy. Partial crystallization of the melt along this cooling curve prior to liquid phase epitaxy results in the liquidus composition required to grow lattice matched material ( XLIn = 0.957, XLGa = 0.008, XLP = 0.035 at 800°C) and a coexisting crystalline phase. The dissolution of the crystalline phase during crystal growth prevents any changes in the liquidus composition, and therefore, enables the growth of thick and constant composition epitaxial layers.

  1. M3B2 and M5B3 Formation in Diffusion-Affected Zone During Transient Liquid Phase Bonding Single-Crystal Superalloys

    NASA Astrophysics Data System (ADS)

    Sheng, Naicheng; Hu, Xiaobing; Liu, Jide; Jin, Tao; Sun, Xiaofeng; Hu, Zhuangqi

    2015-04-01

    Precipitates in the diffusion-affected zone (DAZ) during transient liquid phase bonding (TLP) single-crystal superalloys were observed and investigated. Small size and dendritic-shaped precipitates were identified to be M3B2 borides and intergrowth of M3B2/M5B3 borides. The orientation relationships among M3B2, M5B3, and matrix were determined using transmission electron microscope (TEM). Composition characteristics of these borides were also analyzed by TEM energy-dispersive spectrometer. Because this precipitating phenomenon deviates from the traditional parabolic transient liquid phase bonding model which assumed a precipitates free DAZ during TLP bonding, some correlations between the deviation of the isothermal solidification kinetics and these newly observed precipitating behaviors were discussed and rationalized when bonding the interlayer containing the high diffusivity melting point depressant elements and substrates of low solubility.

  2. A dispersive scattering centers-based strategy for dramatically enhancing the photocatalytic efficiency of photocatalysts in liquid-phase photochemical processes: a case of Ag nanosheets

    NASA Astrophysics Data System (ADS)

    Liu, Chang; Kuang, Qin; Jin, Ming-Shang; Zhang, Jia-Wei; Han, Xi-Guang; Xie, Zhao-Xiong; Zheng, Lan-Sun

    2013-02-01

    A dispersive scattering centers-based strategy was proposed to enhance the photocatalytic efficiency of photocatalysts in liquid-phase photochemical processes. Photocatalytic efficiencies of the photocatalyst, Degussa P25, in water splitting and photodegradation were markedly enhanced by using Ag nanosheets as dispersive scattering centers.A dispersive scattering centers-based strategy was proposed to enhance the photocatalytic efficiency of photocatalysts in liquid-phase photochemical processes. Photocatalytic efficiencies of the photocatalyst, Degussa P25, in water splitting and photodegradation were markedly enhanced by using Ag nanosheets as dispersive scattering centers. Electronic supplementary information (ESI) available: Synthesis of materials and photocatalytic measurement, H2 evolution of Pt-loaded photocatalysts, natural photodegradation of MO, comparison of scattering behaviors of Au NPs and Ag NSs with different concentrations. See DOI: 10.1039/c3nr34203d

  3. The liquid phase epitaxy approach for the successful construction of ultra-thin and defect-free ZIF-8 membranes: pure and mixed gas transport study.

    PubMed

    Shekhah, Osama; Swaidan, Raja; Belmabkhout, Youssef; du Plessis, Marike; Jacobs, Tia; Barbour, Leonard J; Pinnau, Ingo; Eddaoudi, Mohamed

    2014-02-28

    The liquid-phase epitaxy (LPE) method was effectively implemented to deliberately grow/construct ultrathin (0.5-1 ?m) continuous and defect-free ZIF-8 membranes. Permeation properties of different gas pair systems (O2-N2, H2-CO2, CO2-CH4, C3H6-C3H8, CH4-n-C4H10) were studied using the time lag technique. PMID:24448609

  4. Form-stable paraffin\\/high density polyethylene composites as solid–liquid phase change material for thermal energy storage: preparation and thermal properties

    Microsoft Academic Search

    Ahmet Sar?

    2004-01-01

    This paper deals with the preparation of paraffin\\/high density polyethylene (HDPE) composites as form-stable, solid–liquid phase change material (PCM) for thermal energy storage and with determination of their thermal properties. In such a composite, the paraffin (P) serves as a latent heat storage material and the HDPE acts as a supporting material, which prevents leakage of the melted paraffin because

  5. Commercial-scale demonstration of the Liquid Phase Methanol (LPMEOH{trademark}) process. Technical progress report No. 1, October 1, 1993--June 30, 1994

    SciTech Connect

    NONE

    1998-12-31

    The Liquid Phase Methanol (LPMEOH{trademark}) Demonstration Project at Kingsport, Tennessee is a $213.7 million cooperative agreement between the U.S. Department of Energy (DOE) and Air Products and Chemicals, Inc. (Air Products). This document describes major accomplishments in project development for Fiscal Year 1993. The preliminary process hazards review, project safety plan, schedule, and cost management report are included as appendices. The demonstration is sited at the Eastman Chemical Company (Eastman) complex in Kingsport. Air Products and Eastman are working on a partnership agreement which will form the Air Products Liquid Phase Conversion Company, L.P. As a limited partner in the venture, Eastman will own and operate the demonstration unit. The project involves the construction of a 260 tons-per-day (TPD) or 80,000 gallon per day methanol demonstration unit utilizing an existing coal-derived synthesis gas from Eastman. The new equipment consists of synthesis gas feed preparation and compression, liquid phase reactor and auxiliaries, product distillation, and utilities. The technology to be demonstrated was developed by Air Products in a DOE sponsored program that started in 1981. Originally tested at a small, DOE-owned experimental facility in LaPorte, Texas, the LPMEOH{trademark} process offers several advantages over current methods of making methanol. This liquid phase process suspends fine catalyst particles in an inert liquid, forming a slurry. The liquid dissipates heat from the chemical reaction away from the catalyst surface, protecting the catalyst, and allowing the gas-to-methanol reaction to proceed at higher rates. The process is ideally suited to the type of gas produced by modem coal gasifiers. At the Eastman Chemical complex, the technology will be integrated with existing coal gasifiers to demonstrate the commercially important aspects of the operation of the LPMEOH{trademark} Process to produce methanol.

  6. Diffusional limitations in liquid-phase reactions catalyzed by enzymes immobilized on porous supports: sucrose inversion by beta-fructooxidase immobilized on IRA-93 resin.

    PubMed

    Toro, L; Gaudioso, D

    1980-08-01

    An experimental procedure has been proposed to study liquid-phase reactions catalyzed by enzymes immobilized on porous supports. The kinetic behavior can be assessed by experimental runs which allow a separate evaluation of the internal diffusion, the surface kinetics, and the fluid-particle mass transfer. The method has been applied in the study of sucrose inversion by beta-fructooxidase immobilized on IRA-93 resin. PMID:7459692

  7. AlGaN\\/GaN Metal Oxide Semiconductor Heterostructure Field-Effect Transistor Based on a Liquid Phase Deposited Oxide

    Microsoft Academic Search

    Dei-Wei Chou; Kuan-Wei Lee; Jian-Jun Huang; Hou-Run Wu; Yeong-Her Wang; Mau-Phon Houng; Shoou-Jinn Chang; Yan-Kuin Su

    2002-01-01

    AlGaN\\/GaN metal oxide semiconductor heterostructure field-effect transistors (MOSHFETs) with liquid phase deposited SiO2 as the insulating gate are demonstrated. A very large gate swing voltage is applied. An AlGaN\\/GaN MOS heterostructure FET with saturation characteristics is observed. For a gate length of 2 mum in a 5 mum channel opening with a gate width of 100 mum, MOSHFET with transconductance

  8. Effect of catalyst concentration and simulation of precipitation processes on liquid-phase catalytic oxidation of p-xylene to terephthalic acid

    Microsoft Academic Search

    A. Cincotti; R. Orrù; A. Broi; G. Cao

    1997-01-01

    The influence of catalyst concentration, i.e. cobalt naphthenate, on product distribution and kinetic constants of the lumped kinetic scheme of liquid-phase p-xylene oxidation proposed in previous works (cf. Cao et al., 1994a, b) is investigated. The experiments involving various levels of catalyst concentrations (from 1.67 to 33.3 × 10?4 mol\\/kgl) are conducted in an isothermal semi-batch oxidation reactor where both

  9. Transient-mode liquid phase epitaxial growth of GaAs on GaAs-coated Si substrates prepared by migration-enhanced molecular beam epitaxy

    Microsoft Academic Search

    Shuji Nakamura; Shiro Sakai; Shi S. Chang; Ramu V. Ramaswamy; Jae-Hoon Kim; Gouri Radhakrishnan; John K. Liu; Joseph Katz

    1989-01-01

    Planar oxide-maskless growth of GaAs was demonstrated by transient-mode liquid phase epitaxy (TMLPE) on GaAs-coated Si substrates that were prepared by migration-enhanced molecular beam epitaxy (MEMBE). In TMLPE, the cool substrate was brought into contact with hot melts for a short time. A GaAs layer as thick as 30 microns was grown in 10 sec. The etch pits observed in

  10. Optical Properties of High-Quality Ga1-xInxAs1-ySby\\/InAs Grown by Liquid-Phase Epitaxy

    Microsoft Academic Search

    Xiuying Gong; Hirofumi Kan; Tomuo Yamaguchi; Isao Suzuki; Mitsuru Aoyama; Masashi Kumagawa; Nelson Rowell; Aiguo Wang; Robert Rinfret

    1994-01-01

    The photoluminescence (PL) of InAs and GaInAsSb\\/InAs epilayers grown by Gd-doped liquid-phase epitaxy (LPE) has been investigated using a double-modulation Fourier transform infrared spectrometer (FTIR). The spectra were composed of peaks due to band-to-band, band-to-impurities, and exciton recombinations. The excitation power, temperature and Gd concentration dependences of these features were studied. The temperature dependence of the band-to-band transition energies was

  11. InGaP\\/InGaAs\\/GaAs metal-oxide-semiconductor pseudomorphic high electron mobility transistor with a liquid phase oxidized InGaP gate

    Microsoft Academic Search

    Kuan-Wei Lee; Yu-Ju Lin; Nan-Ying Yang; Yu-Chang Lee; Po-Wen Sze; Yeong-Her Wang; Mau-Phon Houng

    2004-01-01

    InGaP\\/InGaAs\\/GaAs metal-oxide-semiconductor pseudomorphic high electron mobility transistors (MOS-PHEMTs) are reported. The gate dielectric is formed by oxidizing InGaP material in liquid phase. As compared to its counterpart PHEMTs, it can be observed that the MOS-PHEMT has a larger gate swing voltage, a lower gate leakage current and a higher breakdown voltage. Consequentially, the studied MOS-PHEMT provides the promise for high-power

  12. Experimental determination of thermal conductivity of solid and liquid phases in Bi?Sn and Zn?Mg binary eutectic alloys

    Microsoft Academic Search

    Mustafa Erol; Kazm Ke?lio?lu; Recep ?ahingöz; Necmettin Mara?l

    2005-01-01

    The thermal conductivities of solid phases, Ks, for Bi-43 wt.% Sn and Zn-0.15 wt.%Mg binary alloys at their eutectic temperature are found to be 28.0 ? 1.4 and 137.4–6.9\\u000a W\\/Km, respectively, with a radial heat flow apparatus. The thermal conductivity ratios, R, of liquid phase to solid phase\\u000a for the same alloys at their eutectic temperature are found to be

  13. Miniaturized hollow fiber assisted liquid-phase microextraction with in situ derivatization and gas chromatography–mass spectrometry for analysis of bisphenol A in human urine sample

    Microsoft Academic Search

    Migaku Kawaguchi; Rie Ito; Noriya Okanouchi; Koichi Saito; Hiroyuki Nakazawa

    2008-01-01

    A new method that involves miniaturized hollow fiber assisted liquid-phase microextraction (HF-LPME) with in situ derivatization and gas chromatography–mass spectrometry (GC–MS) is described for the determination of trace amounts of bisphenol A (BPA) in human urine samples. The detection limit and the quantification limit of BPA in human urine sample are 0.02 and 0.1ngml?1 (ppb), respectively. The calibration curve for

  14. Microstructure-property relationships in digitally generated three-dimensional, two-phase, liquid phase sintered materials

    NASA Astrophysics Data System (ADS)

    Lee, Sukbin

    In studying microstructure-property relationships, it is of great interest to reveal the effect of individual microstructural parameters on the properties of the materials in all three dimensions. However, it is not easy to obtain experimentally samples in which the individual microstructural features are independently controlled. Even though one can prepare such samples, conventional materials characterization is based on the data obtained from two-dimensional plane sections of the samples. Since many problems related to the properties of materials are three-dimensional in nature, conventional two-dimensional characterization is not always sufficient to describe the microstructure quantitatively. Also, many property experiments are destructive and therefore one needs to repeat the process many times to map the properties as a function of the microstructural parameters. Considerable effort has been made to reconstruct three-dimensional microstructures using serial sectioning in recent years in order to determine three-dimensional microstructural features of two-phase composite materials directly. While this approach yields three-dimensional data on the size, shape, and spatial correlation of particles, it demands difficult and time-consuming steps. Thus, numerical reconstruction or synthesis methods can contribute significantly to modeling three-dimensional microstructures, especially two-phase composite microstructures for this project. One objective of this project is to introduce a procedure for generating three-dimensional digital microstructures representing two-phase composite materials containing isotropically coarsened particles in the surrounding matrix phase. In order to achieve the goal, a three-dimensional, Q-state Monte Carlo Potts model of isotropic particle coarsening in a system with full wetting of particles by matrix is introduced to investigate the coarsening kinetics and microstructures associated with this process. By imposing the condition of complete wetting of particles by matrix and the constraint that the site exchange for diffusion of voxels is allowed only for neighboring particle-matrix voxel pairs in the Monte Carlo Potts model, this model can also be used for modeling isotropic coarsening of solid particles during liquid phase sintering. Kinetic Monte Carlo simulation is used to probe the coarsening dynamics and to obtain the characteristics of the solid particles, including the volume of critical nuclei and the distribution of particle size as a function of time. It is found that the average particle volume increases linearly with time and that the particle size distributions are consistent with those obtained experimentally, as in liquid phase sintered W-Ni-Fe and Sn-Pb systems. In obtaining these results, careful consideration is given to the role of initial microstructural conditions in the subsequent evolution of the system. The other objective of this project is to explore the effect of individual microstructural parameters in the hypothetical two-phase microstructures, including ones from the proposed Monte Carlo coarsening simulation, on stress and strain rate fields when uniaxial tension is applied. Using those two-phase digital microstructures as inputs, the microstructure-property relationship study is performed using a viscoplastic simulation based on the Fast Fourier Transform (FFT) algorithm. In the simulations, the dispersed phase consists of hard BCC particles with random spatial orientations while the matrix phase is either (1) a single soft FCC crystal with a fixed spatial orientation or (2)a soft FCC polycrystalline structure with random spatial orientations. A systematic parametric study, varying selected microstructural parameters such as the volume fraction of phases, contiguity of particles and spatial distribution of particles, is employed in order to explore the mechanical response of the hypothetical microstructures under uniaxial tension. It is found that the contiguity of particles, the morphology of the matrix phase in the microstructure, and the polycrystallini

  15. High temperature aqueous potassium and sodium phosphate solutions: two-liquid-phase boundaries and critical phenomena, 275-400/sup 0/C; potential applications for steam generators

    SciTech Connect

    Marshall, W.L.

    1981-12-01

    Two-liquid-phase boundaries at temperatures between 275 and 400/sup 0/C were determined for potassium phosphate and sodium phosphate aqueous solutions for compositions from 0 to 60 wt % dissolved salt. The stoichiometric mole ratios, K/PO/sub 4/ or Na/PO/sub 4/, were varied from 1.00 to 2.12 and from 1.00 to 2.16 for the potassium and sodium systems, respectively. Liquid-vapor critical temperatures were also determined for most of the dilute liquid phases that formed. The minimum temperatures (below which a single solution existed) of two-liquid-phase formation were 360/sup 0/C for the potassium system and 279/sup 0/C for the sodium system at mole ratios of 2.00 and 2.16, respectively. For the sodium system at mole ratios greater than 2.16, solids crystallized at lower temperatures as expected from earlier studies. In contrast, potassium solutions that were explored at mole ratios from 2.12 to 3.16 and at temperatures below 360/sup 0/C did not produce solid phases nor liquid-liquid immiscibilities. Aside from the generally unusual observations of two immiscible liquids in an aqueous inorganic salt system, the results could possibly be applied to the use of phosphate additives in steam power generators. 16 refs.

  16. Investigation on the decomposable process and the secondary liquid phase effect on the dielectric properties of CaCu3Ti4O12 ceramics

    NASA Astrophysics Data System (ADS)

    Yuan, Wenxiang

    2009-09-01

    CaCu3Ti4O12 (CCTO) single-phase powder synthesized by the solid-state reaction method was used to investigate the decomposition reaction after different sintering conditions, in which copper (Cu) atoms played a key role. A secondary intergranular liquid phase (Cu-rich, especially CuO-rich), which is related to both the abnormal grain and the domain boundary growths, started to appear at the grain boundaries when the CCTO pellet was sintered at 1000 °C. The liquid phase improved the dielectric properties of the 1000 °C sample, such as dielectric constant as high as 17 000 and dielectric loss as low as 0.074 at the measured frequency of 1 kHz. Meanwhile, the CuO-rich phase existed only on the surface layers and disappeared from the surface of the pellets sintered at 1100 °C for 10 h. The grain size increased significantly with the sintering temperature. The liquid phase also played an important role in the microstructure evolution and in the improvement of the dielectric properties. In addition, CCTO completely decomposed when sintered for 10 h at temperatures higher than 1100 °C.

  17. Determination of preservatives by integrative coupling method of headspace liquid-phase microextraction and capillary zone electrophoresis.

    PubMed

    Ling, Da-Si; Xie, Hai-Yang; He, You-Zhao; Gan, Wu-Er; Gao, Yong

    2010-12-01

    An integrative coupling method of headspace liquid-phase microextraction (HS-LPME) and capillary zone electrophoresis (CZE) was proposed in this paper. In the method, a separation capillary was used to create a microextraction droplet of the running buffer solution of CZE, hold the droplet at the capillary inlet, extract analytes of sample solutions in the headspace of a sample vial, inject concentrated analytes into the capillary and separate the analytes by CZE. The proposed method was applied to determine the preservatives of benzoic acid and sorbic acid in soy sauce and soft drink samples, in which the running buffer solution of 50 mmol/L tetraborate (pH 9.2) was directly used to form the acceptor droplet at the capillary inlet by pressure, and the preservatives in a 6-mL sample solution containing 0.25 g/mL NaCl were extracted at 90°C for 30 min in the headspace of a 14-mL sample vial. Then the concentrated preservatives were injected into the capillary at 10 cm height difference for 20 s and separated by CZE. The enrichment factors of benzoic acid and sorbic acid achieved 266 and 404, and the limits of detection (LODs) were 0.03 and 0.01 ?g/mL (S/N=3), respectively. The recoveries were in the range of 88.7-105%. The integrative coupling method of HS-LPME and CZE was simple, convenient, reliable and suitable for concentrating volatile and semi-volatile organic acids and eliminating matrix interferences of real samples. PMID:21035121

  18. Order-parameter-aided temperature-accelerated sampling for the exploration of crystal polymorphism and solid-liquid phase transitions

    PubMed Central

    Yu, Tang-Qing; Chen, Pei-Yang; Chen, Ming; Samanta, Amit; Vanden-Eijnden, Eric; Tuckerman, Mark

    2014-01-01

    The problem of predicting polymorphism in atomic and molecular crystals constitutes a significant challenge both experimentally and theoretically. From the theoretical viewpoint, polymorphism prediction falls into the general class of problems characterized by an underlying rough energy landscape, and consequently, free energy based enhanced sampling approaches can be brought to bear on the problem. In this paper, we build on a scheme previously introduced by two of the authors in which the lengths and angles of the supercell are targeted for enhanced sampling via temperature accelerated adiabatic free energy dynamics [T. Q. Yu and M. E. Tuckerman, Phys. Rev. Lett. 107, 015701 (2011)]. Here, that framework is expanded to include general order parameters that distinguish different crystalline arrangements as target collective variables for enhanced sampling. The resulting free energy surface, being of quite high dimension, is nontrivial to reconstruct, and we discuss one particular strategy for performing the free energy analysis. The method is applied to the study of polymorphism in xenon crystals at high pressure and temperature using the Steinhardt order parameters without and with the supercell included in the set of collective variables. The expected fcc and bcc structures are obtained, and when the supercell parameters are included as collective variables, we also find several new structures, including fcc states with hcp stacking faults. We also apply the new method to the solid-liquid phase transition in copper at 1300 K using the same Steinhardt order parameters. Our method is able to melt and refreeze the system repeatedly, and the free energy profile can be obtained with high efficiency. PMID:24907992

  19. pH-Dependent Liquid-Liquid Phase Separation of Highly Supersaturated Solutions of Weakly Basic Drugs.

    PubMed

    Indulkar, Anura S; Box, Karl J; Taylor, Robert; Ruiz, Rebeca; Taylor, Lynne S

    2015-07-01

    Supersaturated solutions of poorly aqueous soluble drugs can be formed both in vivo and in vitro. For example, increases in pH during gastrointestinal transit can decrease the aqueous solubility of weakly basic drugs resulting in supersaturation, in particular when exiting the acidic stomach environment. Recently, it has been observed that highly supersaturated solutions of drugs with low aqueous solubility can undergo liquid-liquid phase separation (LLPS) prior to crystallization, forming a turbid solution such that the concentration of the drug in the continuous solution phase corresponds to the amorphous solubility while the colloidal phase is composed of a disordered drug-rich phase. Although it is well established that the equilibrium solubility of crystalline weakly basic drugs follows the Henderson-Hasselbalch relationship, the impact of pH on the LLPS phenomenon or the amorphous solubility has not been explored. In this work, the LLPS concentration of three weakly basic compounds-clotrimazole, nicardipine, and atazanavir-was determined as a function of pH using three different methods and was compared to the predicted amorphous solubility, which was calculated from the pH-dependent crystalline solubility and by estimating the free energy difference between the amorphous and crystalline forms. It was observed that, similar to crystalline solubility, the experimental amorphous solubility at any pH follows the Henderson-Hasselbalch relation and can be predicted if the amorphous solubility of the free base is known. Excellent agreement between the LLPS concentration and the predicted amorphous solubility was observed. Dissolution studies of amorphous drugs showed that the solution concentration can reach the corresponding LLPS concentration at that pH. Solid-state analysis of the precipitated material confirmed the amorphous nature. This work provides insight into the pH-dependent precipitation behavior of poorly water-soluble compounds and provides a fundamental basis with which to understand the performance of supersaturating dosage forms. PMID:25984769

  20. Polyaromatic hydrocarbons do not disturb liquid-liquid phase coexistence, but increase the fluidity of model membranes.

    PubMed

    Liland, Nina S; Simonsen, Adam C; Duelund, Lars; Torstensen, Bente E; Berntssen, Marc H G; Mouritsen, Ole G

    2014-12-01

    Polyaromatic hydrocarbons (PAHs) is a group of compounds, many of which are toxic, formed by incomplete combustion or thermal processing of organic material. They are highly lipophilic and thus present in some seed oils used for human consumption as well as being increasingly common in aquaculture diets due to inclusion of vegetable oils. Cytotoxic effects of PAHs have been thought to be partly due to a membrane perturbing effect of these compounds. A series of studies were here performed to examine the effects of three different PAHs (naphthalene, phenanthrene and benzo[a]pyrene) with different molecular sizes (two, three and five rings, respectively) and fat solubility (Kow 3.29, 4.53 and 6.04, respectively) on membrane models. The effects of PAHs on liquid-liquid phase coexistence in solid-supported lipid bilayers (dioleoylphosphocholine:dipalmitoylphosphatidylcholine:cholesterol) were assessed using fluorescence microscopy. Benzo[a]pyrene had a slight affinity for the liquid-ordered phase, but there were no effects of adding any of the other PAHs on the number or size of the liquid domains (liquid-ordered and liquid-disordered). Benzo[a]pyrene and phenanthrene, but not naphthalene, lowered the transition temperature (Tm) and the enthalpy (?H) characterising the transition from the solid to the liquid-crystalline phase in DPPC vesicles. The membrane effects of the PAH molecules are likely related to size, with bigger and more fat-soluble molecules having a fluidising effect when embedded in the membrane, possibly causing some of the observed toxic effects in fish exposed to these contaminants. PMID:25181555

  1. Analytical study of the liquid phase transient behavior of a high temperature heat pipe. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Roche, Gregory Lawrence

    1988-01-01

    The transient operation of the liquid phase of a high temperature heat pipe is studied. The study was conducted in support of advanced heat pipe applications that require reliable transport of high temperature drops and significant distances under a broad spectrum of operating conditions. The heat pipe configuration studied consists of a sealed cylindrical enclosure containing a capillary wick structure and sodium working fluid. The wick is an annular flow channel configuration formed between the enclosure interior wall and a concentric cylindrical tube of fine pore screen. The study approach is analytical through the solution of the governing equations. The energy equation is solved over the pipe wall and liquid region using the finite difference Peaceman-Rachford alternating direction implicit numerical method. The continuity and momentum equations are solved over the liquid region by the integral method. The energy equation and liquid dynamics equation are tightly coupled due to the phase change process at the liquid-vapor interface. A kinetic theory model is used to define the phase change process in terms of the temperature jump between the liquid-vapor surface and the bulk vapor. Extensive auxiliary relations, including sodium properties as functions of temperature, are used to close the analytical system. The solution procedure is implemented in a FORTRAN algorithm with some optimization features to take advantage of the IBM System/370 Model 3090 vectorization facility. The code was intended for coupling to a vapor phase algorithm so that the entire heat pipe problem could be solved. As a test of code capabilities, the vapor phase was approximated in a simple manner.

  2. Order-parameter-aided temperature-accelerated sampling for the exploration of crystal polymorphism and solid-liquid phase transitions

    SciTech Connect

    Yu, Tang-Qing, E-mail: tangqing.yu@nyu.edu; Vanden-Eijnden, Eric, E-mail: eve2@cims.nyu.edu [Courant Institute of Mathematical Sciences, New York University, New York, New York 10012 (United States); Chen, Pei-Yang; Chen, Ming [Department of Chemistry, New York University, New York, New York 10003 (United States); Samanta, Amit [Program in Applied and Computational Mathematics, Princeton University, Princeton, New Jersey 08544, USA and Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Tuckerman, Mark, E-mail: mark.tuckerman@nyu.edu [Courant Institute of Mathematical Sciences, New York University, New York, New York 10012 (United States); Department of Chemistry, New York University, New York, New York 10003 (United States); NYU-ECNU Center for Computational Chemistry at NYU Shanghai, Shanghai 200062 (China)

    2014-06-07

    The problem of predicting polymorphism in atomic and molecular crystals constitutes a significant challenge both experimentally and theoretically. From the theoretical viewpoint, polymorphism prediction falls into the general class of problems characterized by an underlying rough energy landscape, and consequently, free energy based enhanced sampling approaches can be brought to bear on the problem. In this paper, we build on a scheme previously introduced by two of the authors in which the lengths and angles of the supercell are targeted for enhanced sampling via temperature accelerated adiabatic free energy dynamics [T. Q. Yu and M. E. Tuckerman, Phys. Rev. Lett. 107, 015701 (2011)]. Here, that framework is expanded to include general order parameters that distinguish different crystalline arrangements as target collective variables for enhanced sampling. The resulting free energy surface, being of quite high dimension, is nontrivial to reconstruct, and we discuss one particular strategy for performing the free energy analysis. The method is applied to the study of polymorphism in xenon crystals at high pressure and temperature using the Steinhardt order parameters without and with the supercell included in the set of collective variables. The expected fcc and bcc structures are obtained, and when the supercell parameters are included as collective variables, we also find several new structures, including fcc states with hcp stacking faults. We also apply the new method to the solid-liquid phase transition in copper at 1300 K using the same Steinhardt order parameters. Our method is able to melt and refreeze the system repeatedly, and the free energy profile can be obtained with high efficiency.

  3. Spin dynamics and disorder effects in the S =1/2 kagome Heisenberg spin-liquid phase of kapellasite

    NASA Astrophysics Data System (ADS)

    Kermarrec, E.; Zorko, A.; Bert, F.; Colman, R. H.; Koteswararao, B.; Bouquet, F.; Bonville, P.; Hillier, A.; Amato, A.; van Tol, J.; Ozarowski, A.; Wills, A. S.; Mendels, P.

    2014-11-01

    We report 35Cl NMR, ESR, ? SR , and specific-heat measurements on the S =1/2 frustrated kagome magnet kapellasite ? -Cu3Zn(OH)6Cl2, where a gapless spin-liquid phase is stabilized by a set of competing exchange interactions. Our measurements confirm the ferromagnetic character of the nearest-neighbor exchange interaction J1 and give an energy scale for the competing interactions |J |˜10 K. The study of the temperature-dependent ESR line shift reveals a moderate symmetric exchange anisotropy term D , with |D /J |˜3 %. These findings validate a posteriori the use of the J1-J2-Jd Heisenberg model to describe the magnetic properties of kapellasite [Bernu et al., Phys. Rev. B 87, 155107 (2013), 10.1103/PhysRevB.87.155107]. We further confirm that the main deviation from this model is the severe random depletion of the magnetic kagome lattice by 27%, due to Cu/Zn site mixing, and specifically address the effect of this disorder by 35Cl NMR, performed on an oriented polycrystalline sample. Surprisingly, while being very sensitive to local structural deformations, our NMR measurements demonstrate that the system remains homogeneous with a unique spin susceptibility at high temperature, despite a variety of magnetic environments. Unconventional spin dynamics is further revealed by NMR and ? SR in the low-T , correlated, spin-liquid regime, where a broad distribution of spin-lattice relaxation times is observed. We ascribe this to the presence of local low-energy modes.

  4. Self- and cross-reactions of ?-hydroxyperoxy radicals of relevance to tropospheric monoterpene oxidation: structure-activity relationships for rate coefficients

    NASA Astrophysics Data System (ADS)

    Boyd, Andrew A.; Villenave, Eric; Lesclaux, Robert

    The laser flash photolysis technique has been used to measure rate coefficients for the self- and cross-reactions of four peroxy radicals, which have been selected as surrogate of those peroxy radicals resulting from the OH addition to monoterpenes: the 2-hydroxycyclohexylperoxy c-C 6H 10(OH)O 2 (I), 2-hydroxy-1,2-dimethylcyclohexylperoxy c-C 6H 8(CH 3) 2(OH)O 2 (II), 2-hydroxy-2-methylcyclohexylperoxy c-C 6H 9(OH)CH 3O 2 (III) and 2-hydroxy-1-methylcyclohexylperoxy c-C 6H 9CH 3(OH)O 2 (IV) radicals. Those radicals were obtained by addition of OH and O 2 to cyclohexene and 1,2-dimethylcyclohexene for I and II, respectively, and to 1-methylcyclohexene for (III) and (IV). Rate constants for self-reactions of radicals I and II are: k8=(1.60±0.10)×10 -12 and k12=(2.00±0.05)×10 -14 (units of cm 3 molecule -1 s -1, errors 2 ?) at 298°K and in 1 atm air. Assuming that both the secondary radicals I and III and both the tertiary radicals II and IV have similar self-reaction rate constants, the rate constant for cross-reaction (13) between III and IV has been determined: k13=(6.15±0.33)×10 -13 cm 3 molecule -1 s -1. The self-reaction rate constant of the peroxy radical c-C 6H 8(OH)O 2, formed by OH and O 2 addition to 1,4-cyclohexadiene, was also estimated and found to be of same order of magnitude as k8, thus showing that the non-conjugated double bond in the radical has no significant effect on the rate constant. Structure-activity relationships are discussed, particularly for self- and cross-reactions involving secondary and tertiary peroxy radicals, in view of their relevance to tropospheric oxidation modelling of alkenes and monoterpenes. In particular, emphasis is given to the large increase in reactivity resulting from the ?-OH substitution, compared to non-substituted species. As part of this work, a rate constant of (1.5±0.5)×10 -14 cm 3 molecule -1 s -1 was measured for the self-reaction of the ?-OH substituted t-butylperoxy radical (CH 3) 2C(O 2)CH 2OH.

  5. Liquid Phase Heating Systems 

    E-print Network

    Mordt, E. H.

    1979-01-01

    Temperature Water (HTW) central district heating systems are far superior to steam systems in large, spread out installations such as airports, universities and office complexes. Water, pressurized to keep it in the liquid state, is distributed at 400o...

  6. Application of hollow fiber liquid phase microextraction for simultaneous determination of regulated and emerging iodinated trihalomethanes in drinking water.

    PubMed

    Domínguez-Tello, A; Arias-Borrego, A; García-Barrera, T; Gómez-Ariza, J L

    2015-07-10

    Trihalomethanes (THMs) are regulated disinfection by-products (DBPs) most commonly analyzed in quality control water supply due to their harmful effects on health. However, few data exist about the content of emerging iodo-trihalomethanes (I-THMs) which are present in drinking water at very low concentrations (in the order of ngL(-1)). For this reason a two-phase hollow fiber liquid phase microextraction method for the simultaneous determination of four regulated trihalomethanes and six emerging iodo-trihalomethanes using GC-?ECD and GC-MS with detection limits in the range of few ngL(-1) has been developed. A central composite design was used to optimize conditions for simultaneous extraction. The best extraction recovery was obtained with 19.2min at 27.1°C and 900rpm, without salt addition, using a supported hollow fiber membrane of 10.5cm (0.6mm id) and 1-octanol as acceptor phase. The limits of detection for the regulated THMs and I-THMs were 3-44ngL(-1) and 1-3ngL(-1), respectively. The calibration curves showed good linearity (R(2)>0.995) and good repeatibility (3-22%). The relative recoveries in water were between 96.5% and 105.2%. The method was applied for the simultaneous determination of trihalomethanes in supply water samples from seven water distribution systems (WDS) in the Huelva area, located at the southwest Spain, which use different water-treatment processes. The highest concentrations of I-THMs, particularly CHBrClI and CHCl2I, were detected in water treated with advanced treatment process using pre-ozonation, however these compounds were not detected or decreased along distribution system. In the samples of treated water with conventional treatment, using pre-oxidation by permanganate and distribution network, CHCl2I, CHBrClI, CHClI2, CHBrI2 and CHI3 were detected at very low concentrations (1-18ngL(-1)). Finally, in water samples from underground origin without oxidation treatment, in which only disinfection with sodium hypochlorite was applied, I-THMs were not detected. PMID:26026483

  7. Seebeck coefficient measurements on Li, Sn, Ta, Mo, and W

    NASA Astrophysics Data System (ADS)

    Fiflis, P.; Kirsch, L.; Andruczyk, D.; Curreli, D.; Ruzic, D. N.

    2013-07-01

    The thermopower of W, Mo, Ta, Li and Sn has been measured relative to stainless steel, and the Seebeck coefficient of each of these materials has then been calculated. These are materials that are currently relevant to fusion research and form the backbone for different possible liquid limiter concepts including TEMHD concepts such as LiMIT. For molybdenum the Seebeck coefficient has a linear rise with temperature from SMo = 3.9 ?V K-1 at 30 °C to 7.5 ?V K-1 at 275 °C, while tungsten has a linear rise from SW = 1.0 ?V K-1 at 30 °C to 6.4 ?V K-1 at 275 °C, and tantalum has the lowest Seebeck coefficient of the solid metals studied with STa = -2.4 ?V K-1 at 30 °C to -3.3 ?V K-1 at 275 °C. The two liquid metals, Li and Sn have also been measured. The Seebeck coefficient for Li has been re-measured and agrees with past measurements. As seen with Li there are two distinct phases in Sn also corresponding to the solid and liquid phases of the metal. In its solid phase the SSn-solid = -1.5 ?V K-1 at 30 °C and -2.5 ?V K-1 near the melting temperature of 231 °C. There is a distinct increase in the Seebeck coefficient around the melting temperature as the Sn melts and stays relatively constant over the rest of the measured temperatures, SSn-melt = -1.4 ?V K-1 from 235 °C to 275 °C.

  8. Liquid-Phase Selective Hydrogenation of Hexa1,5-diene and Hexa1,3-diene on Palladium Catalysts. Effect of Tin and Silver Addition

    Microsoft Academic Search

    Emerson Andrade Sales; Mario de Jesus Mendes; François Bozon-Verduraz

    2000-01-01

    The liquid-phase hydrogenation of hexa-1,5-diene and hexa-1,3-diene on alumina-supported palladium catalysts is investigated with special attention paid to the effects of tin or silver addition. All catalysts show a global selectivity near 100%; these high values persist at total conversion when the reactant is hexa-1,3-diene but decrease to about 70% in the case of hexa-1,5-diene. In the hexa-1,5-diene hydrogenation, monometallic

  9. Thermal expansion and heat capacities of AgBr and AgCl at solid and liquid phases from molecular dynamics simulation

    NASA Astrophysics Data System (ADS)

    Akdere, Ü.

    2015-04-01

    Classical molecular dynamics simulation calculations of silver bromide, AgBr, and silver chloride, AgCl. in constant volume-energy (NVE) and constant pressure-temperature (NPT) ensembles have been performed. The temperature dependence of linear thermal expansion and molar heat capacities at constant volume and pressure have been presented at solid and liquid phases. The anomalous behavior of these properties about 200 K below the melting temperatures has been analyzed within the frame of the onset of the transition to the superionic phase.

  10. Study of liquid-phase dehydration of d,l -1-(4-aminophenyl)ethanol in the presence of acid catalysts

    Microsoft Academic Search

    A. L. Schul’tsev; E. F. Panarin

    2010-01-01

    Thermal acid-catalyzed liquid-phase dehydration of 1-(4-aminophenyl)ethanol at 250–260°C and 30–100 mm Hg was studied. In\\u000a the presence of KHSO4 a 2:1 mixture of 1-amino-4-ethylbenzene with 4-aminostyrene is formed, the use of KHSO4\\/KH2PO4 causes the formation of polymers, and the use of H3BO3 (? 0.26 wt %) in a mixture with KHSO4 allows the preparation of pure 4-aminostyrene. The structure of

  11. Growth and photoluminescence study of low concentration InP layers grown by liquid-phase epitaxy in the presence of erbium

    SciTech Connect

    Mengchyi Wu; Chengming Chiu (National Tsing Hua Univ., Hsinchu (Taiwan, Province of China). Research Inst. of Electrical Engineering); Yuankuang Tu (Telecommunication Lab., Chung-Li (Taiwan, Province of China). Ministry of Communications)

    1993-10-01

    InP layers with electron concentrations as low as 7 [times] 10[sup 13] cm[sup [minus]3] were grown by liquid-phase epitaxy using rare-earth erbium as the donor-gettering source. The presence of Er during growth causes a decrease in electron concentration and the strong suppression of donor-related luminescence transitions due to the effective removal of residual donors in the growth solution. The exciton-related lines of the low concentration InP layers are observed by using Er as the gettering source.

  12. Miniaturized hollow fiber assisted liquid-phase microextraction and gas chromatography–mass spectrometry for determination of benzophenone and derivates in human urine sample

    Microsoft Academic Search

    Migaku Kawaguchi; Rie Ito; Hidehiro Honda; Youji Koganei; Noriya Okanouchi; Koichi Saito; Yasuo Seto; Hiroyuki Nakazawa

    2009-01-01

    The determination of benzophenones (BPs) in human urine sample by miniaturized hollow fiber assisted liquid-phase microextraction (HF-LPME) and gas chromatography–mass spectrometry (GC–MS) is described. As analytes, BP, its metabolites benzhydrol (BP-OH) and 2-hydroxybenzophenone (2OH-BP), and its derivatives 2-hydroxy-4-methoxybenzophenone (BP-3) and 2-hydroxy-4-methoxy-4?-methylbenzophenone (BP-10) were selected. The detection limit and the quantification limit of BPs in human urine sample are 5–10 and

  13. Determination of perchlorate in river by ion-pair hollow-fiber liquid-phase microextraction coupled with electrospray ionization tandem mass spectrometry

    Microsoft Academic Search

    Hsin-Chang Chen; Wen-Tsen Chen; Wang-Hsien Ding

    2009-01-01

    This paper describes the analysis of perchlorate (ClO4?) in surface water samples by a rapid and reliable ion-pair hollow-fiber liquid-phase microextraction (HF-LPME) method coupled with flow-injection electrospray ionization tandem mass spectrometry (ESI-MS–MS) technique. The effects of the type and concentration of ion-pairing reagents, extraction time, temperature and pH value on the quantitative extraction of perchlorate by ion-pair HF-LPME were investigated

  14. Commercial-scale demonstration of the Liquid Phase Methanol (LPMEOH{trademark}) process. Technical progress report number 2, July 1--September 30, 1994

    SciTech Connect

    NONE

    1994-12-31

    The project involves the construction of a 260 tons-per-day (TPD) or 80,000 gallon per day methanol demonstration unit utilizing an existing coal-derived synthesis gas from Eastman. The new equipment consists of synthesis gas feed preparation and compression, liquid phase reactor and auxiliaries, product distillation, and utilities. The technology to be demonstrated was developed by Air Products in a DOE sponsored program that started in 1981. Originally tested at a small, DOE-owned experimental facility in LaPorte, Texas, the LPMEOH{trademark} process offers several advantages over current methods of making methanol. This liquid phase process suspends fine catalyst particles in an inert liquid, forming a slurry. The liquid dissipates heat from the chemical reaction away from the catalyst surface, protecting the catalyst and allowing the gas-to-methanol reaction to proceed at higher rates. The process is ideally suited to the type of gas produced by modern coal gasifiers. At the Eastman Chemical complex, the technology will be integrated with existing coal gasifiers to demonstrate the commercially important aspects of the operation of the LPMEOH{trademark} Process to produce methanol. A four-year demonstration will prove the commercial applicability of the process. An off-site product-use test program will prove the suitability of the methanol as a transportation fuel and as a fuel for stationary applications in the power industry.

  15. Application of hollow fiber-based liquid-phase microextraction (HF-LPME) for the determination of acidic pharmaceuticals in wastewaters.

    PubMed

    Ramos Payán, María; Bello López, Miguel Angel; Fernández-Torres, Rut; Callejón Mochón, Manuel; Gómez Ariza, José Luis

    2010-07-15

    The presence of pharmaceuticals in the environment is a very important problem that requires analytical solutions. The wide variety of matrices and, usually, the low pharmaceuticals levels in the environmental samples requires high sensitive and selective analytical procedures. Wastewaters are one of the more important sources of environmental pollutants but they are very complex matrices that need clean-up procedures prior the analysis. Hollow fiber-based liquid-phase microextraction (HF-LPME) is a relatively new technique used in analytical chemistry for sample pre-treatment that offers high selectivity and sensitivity compared to most traditional extraction techniques. The low organic solvent consumption derived from the use of HF-LPME is according to the current trends to a "Green Chemistry", and Analytical Chemistry should follow these environmental good practices. This paper describes an extraction method using a polypropylene membrane supporting dihexyl ether (three-phase hollow fiber-based liquid-phase microextraction (HF-LPME)) for the direct analysis of three pharmaceuticals (salicylic acid (SAC), ibuprofen (IBU) and diclofenac (DIC)) in raw and treated wastewaters followed by a HPLC/MS-MS determination using a highly packed Pursuit XRs Ultra 2.8 microm C18 column that allows high resolution using low flow-rates and, simultaneously, short retention times. Detection limits were 20, 100 and 300 ng L(-1) for salicylic acid, diclofenac and ibuprofen, respectively. PMID:20602981

  16. Scattered light and accuracy of the cross-section measurements of weak absorptions: Gas and liquid phase UV absorption cross sections of CH3CFCl2

    NASA Technical Reports Server (NTRS)

    Fahr, A.; Braun, W.; Kurylo, M. J.

    1993-01-01

    Ultraviolet absorption cross sections of CH3CFCl2(HCFC-141b) were determined in the gas phase (190-260 nm) and liquid phase (230-260 mm) at 298 K. The liquid phase absorption cross sections were then converted into accurate gas phase values using a previously described procedure. It has been demonstrated that scattered light from the shorter-wavelength region (as little as several parts per thousand) can seriously compromise the absorption cross-section measurement, particularly at longer wavelengths where cross sections are low, and can be a source of discrepancies in the cross sections of weakly absorbing halocarbons reported in the literature. A modeling procedure was developed to assess the effect of scattered light on the measured absorption cross section in our experiments, thereby permitting appropriate corrections to be made on the experimental values. Modeled and experimental results were found to be in good agreement. Experimental results from this study were compared with other available determinations and provide accurate input for calculating the atmospheric lifetime of HCFC-141b.

  17. The effect of TDC temperature and density on the liquid-phase fuel penetration in a D.I. Diesel engine

    SciTech Connect

    Espey, C. [Daimler-Benz AG, Stuttgart (Germany); Dec, J.E. [Sandia National Labs., Albuquerque, NM (United States)

    1995-12-01

    A parametric study of the liquid-phase fuel penetration of evaporating Diesel fuel jets has been conducted in a directinjection Diesel engine using laser elastic-scatter imaging. The experiments were conducted in an optically accessible Diesel engine of the ``heavy-duty`` size class at a representative medium speed (1200 rpm) operating condition. The density and temperature at TDC were varied systematically by adjusting the intake temperature and pressure. At all operating conditions the measurements show that initially the liquid fuel penetrates almost linearly with increasing crank angle until reaching a maximum length. Then, the liquid-fuel penetration length remains fairly constant although fuel injection continues. At a TDC density of 16.6 kg/m{sup 3} and a temperature of about 1000 K the maximum penetration length is approximately 23 mm. However, it varies significantly as TDC conditions are changed, with the liquid-length being less at higher temperatures and at higher densities. The corresponding apparent heat release rate plots are presented and the results of the liquid-phase fuel penetration are discussed with respect to the ignition delay and premixed bum fraction.

  18. High-throughput determination of nicotine in plasma by ultrasonication enhanced hollow fiber liquid-phase microextraction prior to gas chromatography.

    PubMed

    Liu, Xiaotian; Liang, Shumei; Pan, Jie; Guo, Yugao; Luo, Huiru; Zhao, Qingsong; Guan, Shan

    2014-07-01

    In high-throughput ultrasonication enhanced hollow-fiber liquid-phase microextraction (H-U-HF-LPME), ultrasonication was introduced into HF-LPME to enhance the mass transfer rate of the analytes in the two immiscible liquid phases, which resulted in a very short time for extraction equilibrium and a high-throughput analysis. Several parameters were investigated and optimized (such as extraction solvent, temperature of sample, frequency and intensity of ultrasonication, volume of extractant, extraction time, ionic strength of the sample and sample concentration). Based on the results of this study, nicotine was first extracted from a 1.5 mL sample solution under the optimum conditions (ultrasonic power of 50 W with a frequency of 60 kHz, extraction time of 10 min, sodium chloride concentration of 5 mol/L and temperature of 37°C). Next, 0.5 µL of acceptor solution inside the hollow fiber was automatically injected into a gas chromatograph with a flame ionization detector. The results of this study illustrated that the limit of detection, relative standard deviation (n = 6), relative recovery and enrichment factor of nicotine were 0.06 µg/L, 3%, 99.8% and 16.6, respectively. Finally, H-U-HF-LPME was successfully applied for the determination of nicotine in plasma. PMID:23794719

  19. Coefficients of univalent functions

    Microsoft Academic Search

    Peter L. Duren

    1977-01-01

    analytic and univalent in the unit disk \\\\z\\\\ < 1. This is the class of all univalent functions normalized by the conditions \\/(O) = 0 and \\/'(O) = 1. We shall concentrate on coefficient problems for the class S and for related classes, with emphasis on recent results and open problems. Most of the methods we shall describe have wide

  20. Precision measurements of binary and multicomponent diffusion coefficients in protein solutions relevant to crystal growth: Lysozyme chloride in water and aqueous NaCl at pH 4.5 and 25°C

    Microsoft Academic Search

    John G. Albright; Onofrio Annunziata; Donald G. Miller; Luigi Paduano; Arne J. Pearlstein

    1999-01-01

    Accurate models of protein diffusion are important in a number of applications, including liquid-liquid phase separation and growth of protein crystals for X-ray diffraction studies. In concentrated multicomponent protein systems, significant deviations from pseudobinary behavior can be expected. Rayleigh interferometry is used to measure the four elements (D{sub if}){sub v} of the ternary diffusion coefficient matrix for the extensively investigated

  1. Growth rate dependence of rare-earth segregation in the liquid-phase epitaxy of magnetic garnet films

    NASA Astrophysics Data System (ADS)

    Gualtieri, D. M.; Tumelty, P. F.

    1982-03-01

    Epitaxial films of the archetypical bubble garnet (R, Y)3Fe5O12, where R is a rare earth, were grown on (111) Gd3Ga5O12 substrates from a 200:1 by weight PbO:B2O3 flux using the horizontal dipping technique with rotation. Growth rate was varied by adjusting supercooling and rotation rate, and the equilibrium segregation coefficients of the dodecahedrally crystallizing cations KR = Rxtal/Rmelt were determined with reference to the film-lattice constant and the segregation of these cations on octahedral sites. KR was found to obey the growth model of Burton, Prim, and Slichter [J. Chem. Phys. 21, 1987 (1953)], KR = KR0/[KR0+(1-KR0)e-kf], where f is the growth rate, KR0 is the segregation coefficient at zero growth rate, and k is a parameter which is a function of the thickness of the growth interface and the diffusion constant. The parameter k was found to be independent of the species R and to have the value 1.18 sec ?m-1 for the particular growth condition. A strong correlation was found between KR0 and the partial molar heat of mixing of the R2O3 oxide and the flux, as calculated from regular solution theory [D. M. Gualtieri, J. Appl. Phys. 50, 2170 (1979)].

  2. Total individual ion activity coefficients of calcium and carbonate in seawater at 25°C and 35%. salinity, and implications to the agreement between apparent and thermodynamic constants of calcite and aragonite

    NASA Astrophysics Data System (ADS)

    Plummer, L. Niel; Sundquist, Eric T.

    1982-02-01

    We have calculated the total individual ion activity coefficients of carbonate and calcium, ? TCO 32- and ? TCa 2+, in seawater. Using the ratios of stoichiometric and thermodynamic constants of carbonic acid dissociation and total mean activity coefficient data measured in seawater, we have obtained values which differ significantly from those widely accepted in the literature. In seawater at 25°C and 35%. salinity the (molal) values of ? TCO 23- and ? TCa 2+ are 0.038 ± 0.002 and 0.173 ± 0.010, respectively. These values of ? TCO 32- and ? TCa 2+ are independent of liquid junction errors and internally consistent with the value ? TCl - = 0.651 . By defining ? TCa 2+ and ? TCO 32- on a common scale ( ? TCl -), the product ? TCa 2+? TCO 32- is independent of the assigned value of ? Cl - and may be determined directly from thermodynamic measurements in seawater. Using the value ? TCa 2+? TCO 32- = 0.0067 and new thermodynamic equilibrium constants for calcite and aragonite, we show that the apparent constants of calcite and aragonite are consistent with the thermodynamic equilibrium constants at 25°C and 35%. salinity. The demonstrated consistency between thermodynamic and apparent constants of calcite and aragonite does not support a hypothesis of stable Mg-calcite coatings on calcite or aragonite surfaces in seawater, and suggests that the calcite critical carbonate ion curve of Broecker and Takahashi (1978, Deep-Sea Research25, 65-95) defines the calcite equilibrium boundary in the oceans, within the uncertainty of the data.

  3. Network modeling of diffusion coefficients for porous media: II. Simulations

    SciTech Connect

    Steele, D.D. [North Dakota State Univ., Fargo, ND (United States); Nieber, J.L. [Univ. of Minnesota, St. Paul, MN (United States)

    1994-09-01

    Gas diffusion often dominates constituent in porous media (PM) and it dependent on pore geometry, water content, and water distribution in PM. Network models of PM offer the ability to investigate the influence and interaction of pore-scale PM properties and fluid properties on macroscopic properties of the system. This study was conducted to investigate the macroscopic relative gas diffusion coefficient vs. air-filled porosity relationship or diffusion characteristic (DC) of PM using a network model. The network model was used to simulate DCs in wetting and drying PM containing air and water. A network size of nine by nine spheres was used; increasing the network size to 19 by 19 by 19 produced essentially no change in the DC. The DC was independent of Henry`s law gas-liquid partition coefficient (H) for H values of 0.1, 1.0, and 5.0. The product HR{sub W}, where R{sub W} is the ratio between the bulk gas- and liquid-phase diffusion coefficients, strongly influences the DC when H values of 1000 to 10 000 are considered; this indicates that certain organic compounds have DCs independent of air-filled porosity. Hysteresis in DCs was found in selected network cases, with the wetting DCs being greater than the drying DCs for most air-filled porosities, in accord with some experimental results reported in the literature. Spatial correlation of network pore space was shown to bring the simulated DCs into better agreement with some experimental DCs. 23 refs., 10 figs., 3 tabs.

  4. AN ERGONOMIC ASSESSMENT OF FOUR FEMALE SHOES: FRICTION COEFFICIENTS OF THE SOLES ON THE FLOORS AND ELECTROMYOGRAPHIC ACTIVITIES IN THE SHANK WHEN WALKING

    Microsoft Academic Search

    2003-01-01

    There are two commonly held beliefs concerning high-heeled shoes for females. The first is that high-heeled shoes are prone to cause slipping accidents. The second is that high-heeled shoes heighten the muscular load on the lower legs more than low-heeled shoes. Reports on high-heeled shoe slip resistance assessment together with a discussion on leg muscular activities when wearing high heels

  5. Fabrication of Controllable Pore and Particle Size of Mesoporous Silica Nanoparticles via a Liquid-phase Synthesis Method and Its Absorption Characteristics

    NASA Astrophysics Data System (ADS)

    Nandiyanto, Asep Bayu Dani; Iskandar, Ferry; Okuyama, Kikuo

    2011-12-01

    Monodisperse spherical mesoporous silica nanoparticles were successfully synthesized using a liquid-phase synthesis method. The result showed particles with controllable pore size from several to tens nanometers with outer diameter of several tens nanometers. The ability in the control of pore size and outer diameter was altered by adjusting the precursor solution ratios. In addition, we have conducted the adsorption ability of the prepared particles. The result showed that large organic molecules were well-absorbed to the prepared silica porous particles, in which this result was not obtained when using commercial dense silica particle and/or hollow silica particle. With this result, the prepared mesoporous silica particles may be used efficiently in various applications, such as sensors, pharmaceuticals, environmentally sensitive pursuits, etc.

  6. Sedimentation of a two-dimensional colloidal mixture exhibiting liquid-liquid and gas-liquid phase separation: a dynamical density functional theory study.

    PubMed

    Malijevský, Alexandr; Archer, Andrew J

    2013-10-14

    We present dynamical density functional theory results for the time evolution of the density distribution of a sedimenting model two-dimensional binary mixture of colloids. The interplay between the bulk phase behaviour of the mixture, its interfacial properties at the confining walls, and the gravitational field gives rise to a rich variety of equilibrium and non-equilibrium morphologies. In the fluid state, the system exhibits both liquid-liquid and gas-liquid phase separation. As the system sediments, the phase separation significantly affects the dynamics and we explore situations where the final state is a coexistence of up to three different phases. Solving the dynamical equations in two-dimensions, we find that in certain situations the final density profiles of the two species have a symmetry that is different from that of the external potentials, which is perhaps surprising, given the statistical mechanics origin of the theory. The paper concludes with a discussion on this. PMID:24116640

  7. Liquid-phase microextraction of tributyltin and triphenyltin coupled with gas chromatography-tandem mass spectrometry. Comparison between 4-fluorophenyl and ethyl derivatizations.

    PubMed

    Shioji, Hirotaka; Tsunoi, Shinji; Harino, Hiroya; Tanaka, Minoru

    2004-09-01

    This paper describes the liquid-phase microextraction (LPME) of tributyltin (TBT) and triphenyltin coupled with gas chromatography-tandem mass spectrometry. The 4-fluorophenylation and ethylation reactions were used for the derivatization of the organotins. For the two derivatizations, the LPME parameters such as organic solvent, stirring rate, temperature, extraction time and the other additional conditions were examined. Using pure water, the calibration curves, method detection limits (MDLs) and reproducibilities (RSDs) of the two derivatizations were compared under the respective optimized procedures. The 4-fluorophenyl derivatization, which showed a lower MDL (0.36 ng/l) and better reproducibility (RSD = 11% at 10 ng/l) for TBT, was applied to the analysis of seawater. The TBT was detected in the range from 1.1 to 2.0 ng/l in the seawater samples collected in Osaka Bay. PMID:15453422

  8. New method for the determination of bile acids in human plasma by liquid-phase microextraction using liquid chromatography-ion-trap-time-of-flight mass spectrometry.

    PubMed

    de Paiva, Maria José Nunes; Menezes, Helvécio Costa; da Silva, Júlio César Cardoso; Resende, Rodrigo Ribeiro; Cardeal, Zenilda de Lourdes

    2015-04-01

    Bile acids (BAs) are derived from cholesterol and produced in the liver. The most abundant bile acids in humans are usually conjugated with glycine and taurine and are divided into primary BAs such as cholic acid (CA) and chenodeoxycholic acid (CDCA) and secondary BAs like deoxycholic acid (DCA), lithocholic acid (LCA) and ursodeoxycholic acid (UDCA). The differences amongst individual bile acids (BAs) are significant in order to distinguish different pathological processes and exposure to chemical compounds. Hollow fiber based liquid-phase microextraction (HF-LPME) is a technique that combines sample cleansing, extraction and the concentration of analytes, where a hydrophobic porous capillary membrane is impregnated with an organic extraction solvent and the lumen is filled with microliters of a phase acceptor both organic by nature. The aim of this study was to develop a new method to extract bile acids from plasma through HF-LPME of two phases (octanol as the acceptor phase) using LCMS-IT-TOF. The optimized two-phased LPME procedure for the extraction of bile acids showed limits of detection 1.0 ?g L(-1) and limits of quantification of 5.0 ?g L(-1). The intra-assay precision ranged from 2.1 to 11.9%. The method developed was linear over the range of 5.0-200.0 ?g L(-1) for all analytes. The hollow-fiber liquid-phase microextraction method was applied to human plasma from workers exposed to organic and halogenated solvents and also to unexposed volunteers. The method is simple, low cost and it does not require large amounts of organic solvents, therefore it is quite suitable for the analysis of bile acids exposed to hepatotoxic compounds. PMID:25721909

  9. Understanding the stabilization of liquid-phase-exfoliated graphene in polar solvents: molecular dynamics simulations and kinetic theory of colloid aggregation.

    PubMed

    Shih, Chih-Jen; Lin, Shangchao; Strano, Michael S; Blankschtein, Daniel

    2010-10-20

    Understanding the solution-phase dispersion of pristine, unfunctionalized graphene is important for the production of conducting inks and top-down approaches to electronics. This process can also be used as a higher-quality alternative to chemical vapor deposition. We have developed a theoretical framework that utilizes molecular dynamics simulations and the kinetic theory of colloid aggregation to elucidate the mechanism of stabilization of liquid-phase-exfoliated graphene sheets in N-methylpyrrolidone (NMP), N,N'-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), ?-butyrolactone (GBL), and water. By calculating the potential of mean force between two solvated graphene sheets using molecular dynamics (MD) simulations, we have found that the dominant barrier hindering the aggregation of graphene is the last layer of confined solvent molecules between the graphene sheets, which results from the strong affinity of the solvent molecules for graphene. The origin of the energy barrier responsible for repelling the sheets is the steric repulsions between solvent molecules and graphene before the desorption of the confined single layer of solvent. We have formulated a kinetic theory of colloid aggregation to model the aggregation of graphene sheets in the liquid phase in order to predict the stability using the potential of mean force. With only one adjustable parameter, the average collision area, which can be estimated from experimental data, our theory can describe the experimentally observed degradation of the single-layer graphene fraction in NMP. We have used these results to rank the potential solvents according to their ability to disperse pristine, unfunctionalized graphene as follows: NMP ? DMSO > DMF > GBL > H(2)O. This is consistent with the widespread use of the first three solvents for this purpose. PMID:20879739

  10. Structure, morphology and cell affinity of poly(L-lactide) films surface-functionalized with chitosan nanofibers via a solid-liquid phase separation technique.

    PubMed

    Zhao, Jianhao; Han, Wanqing; Tang, Minjian; Tu, Mei; Zeng, Rong; Liang, Zhihong; Zhou, Changren

    2013-04-01

    Poly(L-lactide) films with a nano-structured surface by immobilizing chitosan nanofibers (CSNFs) for improving the cell affinity were fabricated via a solid-liquid phase separation technique. The successful grafting of CSNFs on the surface of poly(L-lactide) films was confirmed by the binding energy of N1s at 398.0 eV in the X-ray photoelectron spectroscopy and the amide I and II bands of chitosan at 1650 and 1568 cm(-1) in the Fourier transform infrared spectroscopy. Compared with the poly(L-lactide) film, the hydrophilicity was improved with a lower water contact angle of 83.3±1.9° and 75.3±2.5° for the CSNFs-grafted and CSNFs-grafted/anchored poly(L-lactide) films respectively. The scanning electron microscopy and atomic force microscopy analyses showed that the grafted CSNFs with 50-500 nm in diameter were randomly arranged on the film surface and entangled with the anchored CSNFs on the outermost layer. The 3T3 fibroblasts culture indicated cells tended to attach and stretch along the CSNFs on the film surface. The cell viability measurement revealed that among all the samples, the film with both grafted and anchored CSNFs exhibited the highest cell proliferation rate that was twice as much of the poly(L-lactide) film at 7 d. Herein, engineering a nano-structured surface by solid-liquid phase separation will be a promising tool for surface modification of biomaterials. PMID:23827607

  11. Revolving hollow fiber-liquid phase microextraction coupled to GC/MS using electron ionization for quantification of five aromatic hydrocarbon isomers.

    PubMed

    Chen, Yuan-Chin; Wu, Hui-Fen

    2009-09-01

    A dynamic liquid phase microextraction method using a revolving hollow fiber was demonstrated for coupling to GC/MS [using EI (electronic ionization) and selected ion monitor (SIM)] as a concentrating probe for rapid analysis and quantitative determination of five aromatic hydrocarbon isomers (cumene; propylbenzene; 2-ethyltoluene; 1,2,3-trimethylbenzene; and 1,2,4-trimethylbenzene) from biological matrices (human urine and human plasma). This technique was named as revolving hollow fiber-liquid phase microextraction (RHF-LPME). The optimized parameters of RHF-LPME coupled to GC/MS experiments were extraction solvent, toluene; extraction time, 2 min; sample agitation rate, 700 rpm; salt concentration, 0%; rotating speed for motor driving rotator, 250 rpm; and the rotator was operated in a reversed direction with the stirrer. The linear range of calibration curve of RHF-LPME was from 0.002 to 0.4 microg/mL with R(2) > 0.9916 and the RSD values were from 4.5 to 5.2%. Additionally, comparing to single drop microextraction (SDME), this method offers better limits of detection (LODs) and EF (enrichment factor). This approach exhibits many advantages including simplicity, rapid detection with high reproducibility and high extraction efficiency, easy to operate and fast to reach equilibrium for analyzing biological samples. This approach has the potential to be widely used because it only requires simple devices to perform all extraction processes. We believe that this technique can be a powerful tool for GC/MS analysis of biological samples and clinical applications in the near future. PMID:19714662

  12. EQUILIBRIUM ARSENIC CAPACITY OF ACTIVATED ALUMINA

    EPA Science Inventory

    Arsenic(V) can be effectively removed from water by adsorption onto activated alumina. Variables affecting the extent of adsorption include pH, temperature, and the presence of other ions in solution. Adsorption isotherms establishing a relation between solid and liquid phase ars...

  13. Total individual ion activity coefficients of calcium and carbonate in seawater at 25??C and 35%. salinity, and implications to the agreement between apparent and thermodynamic constants of calcite and aragonite

    USGS Publications Warehouse

    Plummer, L.N.; Sundquist, E.T.

    1982-01-01

    We have calculated the total individual ion activity coefficients of carbonate and calcium, ??TCO32- and ??TCa2+, in seawater. Using the ratios of stoichiometric and thermodynamic constants of carbonic acid dissociation and total mean activity coefficient data measured in seawater, we have obtained values which differ significantly from those widely accepted in the literature. In seawater at 25??C and 35%. salinity the (molal) values of ??TCO23- and ??TCa2+ are 0.038 ?? 0.002 and 0.173 ?? 0.010, respectively. These values of ??TCO32- and ??TCa2+ are independent of liquid junction errors and internally consistent with the value ??TCl- = 0.651. By defining ??TCa2+ and ??TCO32- on a common scale (??TCl-), the product ??TCa2+??TCO3 2- is independent of the assigned value of ??Cl- and may be determined directly from thermodynamic measurements in seawater. Using the value ??TCa2+??TCO3 2- = 0.0067 and new thermodynamic equilibrium constants for calcite and aragonite, we show that the apparent constants of calcite and aragonite are consistent with the thermodynamic equilibrium constants at 25??C and 35%. salinity. The demonstrated consistency between thermodynamic and apparent constants of calcite and aragonite does not support a hypothesis of stable Mg-calcite coatings on calcite or aragonite surfaces in seawater, and suggests that the calcite critical carbonate ion curve of Broecker and Takahashi (1978, Deep-Sea Research 25, 65-95) defines the calcite equilibrium boundary in the oceans, within the uncertainty of the data. ?? 1982.

  14. Coefficients of associated Legendre functions

    NASA Technical Reports Server (NTRS)

    Peasley, Q. D.

    1976-01-01

    The exact coefficients for the explicit forms of the associated Legendre functions Pm for integer values of m,n=0,1,2,...25 are presented in tabular form together with two cross-referenced listings of the zeroes for these functions rounded to five decimal places. The unfactored coefficients and the interger coefficients are presented in adjacent columns for each function. The greatest common factor and divisor have been removed and listed separately for the integer coefficients.

  15. Similarity coefficients for binary data: properties of coefficients, coefficient matrices, multi-way metrics and multivariate coefficients

    Microsoft Academic Search

    Matthijs Joost Warrens

    2008-01-01

    In data analysis, an important role is played by similarity coefficients. A similarity coefficient is a measure of resemblance or association of two entities or variables. Similarity coefficients for binary data are used, for example, in biological ecology for measuring the degree of coexistence between two species type over different locations, or in psychology for a 2×2 reliability study where

  16. Keggin heteropolycompounds as catalysts for liquid-phase oxidation of sulfides to sulfoxides\\/sulfones by hydrogen peroxide

    Microsoft Academic Search

    Gustavo P. Romanelli; Paula I. Villabrille; Cármen V. Cáceres; Patricia G. Vázquez; Pietro Tundo

    2011-01-01

    H4PMo11VO40, H5PMo10V2O40 and H9PMo6V6O40 acids and an acidic pyridinium salt of H4PMo11VO40 were synthesized. They were characterized by FT-IR and the variations of their acid properties were determined by titration with n-butylamine. They proved to be highly active and selective catalysts for the hydrogen peroxide oxidation of methyl phenyl sulfide to the corresponding sulfoxide or sulfone. The conversion and selectivity

  17. The potential of organic (electrospray- and atmospheric pressure chemical ionisation) mass spectrometric techniques coupled to liquid-phase separation for speciation analysis.

    PubMed

    Rosenberg, Erwin

    2003-06-01

    The use of mass spectrometry based on atmospheric pressure ionisation techniques (atmospheric pressure chemical ionisation, APCI, and electrospray ionisation, ESI) for speciation analysis is reviewed with emphasis on the literature published in and after 1999. This report accounts for the increasing interest that atmospheric pressure ionisation techniques, and in particular ESI, have found in the past years for qualitative and quantitative speciation analysis. In contrast to element-selective detectors, organic mass spectrometric techniques provide information on the intact metal species which can be used for the identification of unknown species (particularly with MS-MS detection) or the confirmation of the actual presence of species in a given sample. Due to the complexity of real samples, it is inevitable in all but the simplest cases to couple atmospheric pressure MS detection to a separation technique. Separation in the liquid phase (capillary electrophoresis or liquid chromatography in reversed phase, ion chromatographic or size-exclusion mode) is particularly suitable since the available techniques cover a very wide range of analyte polarities and molecular mass. Moreover, derivatisation can normally be avoided in liquid-phase separation. Particularly in complex environmental or biological samples, separation in one dimension is not sufficient for obtaining adequate resolution for all relevant species. In this case, multi-dimensional separation, based on orthogonal separation techniques, has proven successful. ESI-MS is also often used in parallel with inductively coupled plasma MS detection. This review is structured in two parts. In the first, the fundamentals of atmospheric pressure ionisation techniques are briefly reviewed. The second part of the review discusses recent applications including redox species, use of ESI-MS for structural elucidation of metal complexes, characterisation and quantification of small organometallic species with relevance to environment, health and food. Particular attention is given to the characterisation of biomolecules and metalloproteins (metallothioneins and phytochelatins) and to the investigation of the interaction of metals and biomolecules. Particularly in the latter field, ESI-MS is the ideal technique due to the softness of the ionisation process which allows to assume that the detected gas-phase ions are a true representation of the ions or ion-biomolecule complexes prevalent in solution. It is particularly this field, important to biochemistry, physiology and medical chemistry, where we can expect significant developments also in the future. PMID:12877203

  18. Gas-phase adsorption in dealuminated natural clinoptilolite and liquid-phase adsorption in commercial DAY zeolite and modified ammonium Y zeolite

    NASA Astrophysics Data System (ADS)

    Costa Hernandez, Alba Nydia

    The adsorption of Carbon Dioxide (CO2) is a very important tool for the material characterization. On the other hand, in separation and recovery technology, the adsorption of the CO2 is important to reduce the concentration of this gas considered as one of the greenhouse gases. Natural zeolites, particularly clinoptilolite, are widely applied to eliminate some pollutants from the environment. One of the goals of this research is to study the structure, composition and morphology of one natural clinoptilolite dealuminated with ammonium hexafluorosilicate (AHFi) and with orthophosphoric acid (H3PO4). Each modified sample was characterized using X-ray Diffraction (XRD), Carbon Dioxide adsorption at 0° C, Thermogravimetric Analysis (TGA), and Scanning Electron Microscopy with Energy Dispersive X-Ray Analysis (SEM-EDAX). In addition, the surface chemistry of the modified clinoptilolites was analyzed with Diffuse Reflectance Fourier Transform Infrared Spectroscopy (DRIFTS). The adsorption measurements were also used to study of the interaction of CO2 molecule within the adsorption space of these modified clinoptilolites. It was concluded that one of the modified clinoptilolites, (CSW-HFSi-0.1M), showed a great quality as adsorbent and as catalytic comparable to commercial synthetic zeolites. As far as we know, the modification of clinoptilolite with HFSi to improve their adsorption properties had not been previously attempted. In the second part of this dissertation, the dynamic adsorption of three isomers of nitrophenols using as adsorbent a commercial DAY zeolite was investigated. Also, the dynamic adsorption of methanol in a less hydrophobic zeolite, Ammonium Y Zeolite was investigated. The obtained breakthrough curves showed that the commercial DAY zeolite could be a suitable adsorbent to the liquid-phase adsorption of the phenolic compounds. Notwithstanding the modified ammonium Y zeolite had a low Si/Al ratio (less hydrophobic) than commercial DAY zeolite; this modified zeolite was useful for the dynamic adsorption of polar compound such as methanol. The obtained results were consistent with those reported in other studies related with the use of zeolites in the removal of organic compounds from the liquid phase.

  19. Hybrid flow analyzer for automatic hollow-fiber-assisted ionic liquid-based liquid-phase microextraction with in-line membrane regeneration.

    PubMed

    Nitiyanontakit, Sira; Varanusupakul, Pakorn; Miró, Manuel

    2013-04-01

    The proof-of-concept of a new methodology for in-line hollow-fiber (HF)-assisted three-phase liquid-phase microextraction (LPME) allowing for handling of the feed and acceptor aqueous solutions and of minute volumes of the organic extracting phase in a programmable flow mode is reported in this paper. The flow analyzer fosters in-line anchoring of ionic-liquid-laden extracting solution (10 % (v/v) methyltrioctyl ammonium chloride in kerosene) in the pores of a single-strand microporous polypropylene HF, and regeneration of the liquid-phase membrane itself for each individual analysis cycle in a fully automated mode. Using hexavalent chromium as a model analyte and 1,5-diphenylcarbazide as a chromogenic probe in the acceptor solution, the flow-based HF-LPME hyphenated system was harnessed to the clean-up of troublesome samples (viz., domestic wastewater and soil leachates) with concomitant enrichment of target species. Distinct extraction modes and chemistries were assessed for enhanced Cr(VI) permeability. A single sample plug was subjected to a twofold backward-forward flow extraction so as to decrease the thickness of the boundary layer at the HF shell side for improved extraction efficiency. Under the optimized physicochemical variables, a limit of detection of 4.6 ?g L(-1) Cr(VI), a dynamic linear range of up to 500 ?g L(-1) and intermediate precision better than 10 % were obtained for a sample volume of 2.8 mL buffered at pH 4 and a volume of organic extractant of 120 ?L, with an enrichment factor of ca. 11 for a sample residence time in the donor compartment of merely 4.5 min. Analyte recoveries in domestic wastewaters were ?83 % using external calibration with relative standard deviations better than 14 %, thereby demonstrating the expedient clean-up of samples with elevated content of dissolved organic carbon. The automatic HF-LPME method was validated in terms of bias against the SRM 2701 (NIST soil) preceded by the EPA alkaline digestion method 3060A. No significant differences between Cr(VI) concentration as obtained with the automatic HF-LPME system (546 ± 57 mg kg(-1)) and the certified value (551.2 ± 17.2 mg kg(-1), expressed as mean ± combined uncertainty) were encountered at the 0.05 significance level. PMID:23386000

  20. Drag Coefficient of Hexadecane Particles

    NASA Astrophysics Data System (ADS)

    Nakao, Yoshinobu; Hishida, Makoto; Kajimoto, Sadaaki; Tanaka, Gaku

    This paper deals with the drag coefficient of solidified hexadecane particles and their free rising velocity in liquid. The drag coefficient was experimentally investigated in Reynolds number range of about 40-300. The present experimental results are summarized in the following; (1) the drag coefficient of solidified hexadecane particles formed in liquid coolant by direct contact cooling is higher than that of a smooth surface sphere, this high drag coefficient seems to be attributed to the non-smooth surface of the solidified hexadecane particles, (2) experimental correlation for the drag coefficient of the solidified hexadecane particles was proposed, (3 ) the measured rising velocity of the solidified hexadecane particle agrees well with the calculated one, (4) the drag coefficients of hexadecane particles that were made by pouring hexadecane liquid into a solid hollow sphere agreed well with the drag coefficient of smooth surface sphere.