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1

Liquid Phase Adsorption of ?-Tocopherol by Activated Carbon  

NASA Astrophysics Data System (ADS)

?-Tocopherol or commonly called vitamin E can be found in major commercial vegetable oils such as soya oil and palm oil. However the existence in these oil is in low concentration. The recovery of low concentration of ?-tocopherol from palm oils is increasingly popular. Adsorption technique for the recovery of ?-tocopherol from palm oil is believed to be much lower in cost and more effective. As a case study in this work, activated carbon is chosen as the adsorbent and ethanol as the solvent. The adsorption equilibria of ?-tocopherol onto activated carbon was conducted in batch and the concentration of ?-tocopherol was identified by LCMS. Langmuirian monolayer adsorption theory was used for the analysis of the isotherm equilibria. The adsorptivity of ?-tocopherol onto activated carbon was identified. The adsorption equilibria at low concentration found to be linear. The breakthrough curve was then generated using model assuming isothermal, single transition trace component with intraparticle diffusion. Sensitivity test on the curve indicated that the system is very sensitive to changes in diffusitivity and passive to changes on the equilibrium constant.

Bono, Awang; Ming, Chu Chi; Sundang, Murni

2

Kinetic characteristics of liquid phase sintering of mechanically activated W-15wt%Cu powder  

Microsoft Academic Search

The kinetic characteristics of W grain growth operated by diffusion controlled Oswald ripening (DOR) during liquid phase sintering were studied. A liquid phase sintering of W-15wt%Cu was carried out by pushing compacts into a furnace at the moment when the temperature increased to 1340° for different sintering times. The results show that liquid phase sintering produces the compacts with considerably

Zhigang Li; Chengchang Jia; Yuntao He; Liliang Chen

2006-01-01

3

Liquid-phase adsorption of organic compounds by granular activated carbon and activated carbon fibers  

SciTech Connect

Liquid-phase adsorption of organic compounds by granular activated carbon (GAC) and activated carbon fibers (ACFs) is investigated. Acetone, isopropyl alcohol (IPA), phenol, and tetrahydrofuran (THF) were employed as the model compounds for the present study. It is observed from the experimental results that adsorption of organic compounds by GAC and ACF is influenced by the BET (Brunauer-Emmett-Teller) surface area of adsorbent and the molecular weight, polarity, and solubility of the adsorbate. The adsorption characteristics of GAC and ACFs were found to differ rather significantly. In terms of the adsorption capacity of organic compounds, the time to reach equilibrium adsorption, and the time for complete desorption, ACFs have been observed to be considerably better than GAC. For the organic compounds tested here, the GAC adsorptions were shown to be represented well by the Langmuir isotherm while the ACF adsorption could be adequately described by the Langmuir or the Freundlich isotherm. Column adsorption tests indicated that the exhausted ACFs can be effectively regenerated by static in situ thermal desorption at 150 C, but the same regeneration conditions do not do as well for the exhausted GAC.

Lin, S.H.; Hsu, F.M. [Yuan Ze Inst. of Tech., Taoyuan (Taiwan, Province of China). Dept. of Chemical Engineering

1995-06-01

4

Correlation of biocatalytic activity in an organic-aqueous two-liquid phase system with solvent concentration in the cell membrane.  

PubMed

Results presented here show that loss of progesterone 11 alpha-hydroxylase activity in Rhizopus nigricans in aqueous-organic two-liquid phase and cosolvent systems correlates well with the concentration of solvent in the cell membranes. Rhizopus nigricans is shown to retain full 11 alpha-hydroxylase activity at saturating aqueous phase concentrations of hexane and the higher primary alcohols. This reflects their inability to attain a critical concentration in the cell membranes. The relationship between our own findings and the previously described correlation of the logarithm of the partition coefficient with activity retention is explained and design parameters are proposed that may be used to select solvents for future biocatalytic systems. PMID:1366443

Osborne, S J; Leaver, J; Turner, M K; Dunnill, P

1990-04-01

5

Liquid-Phase Adsorption Fundamentals.  

ERIC Educational Resources Information Center

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)

Cooney, David O.

1987-01-01

6

Characterization and use of activated carbons prepared from bagasses for liquid-phase adsorption  

Microsoft Academic Search

The adsorption of two commercial dyes and phenol from water on activated carbons was investigated at 30°C. The carbons were prepared from bagasses and were activated by steam with different extents of burn-off by varying the temperature in the range of 750–840°C. Pore structures of the carbons were characterized by the t-plot method based on N2 adsorption isotherms. Three simplified

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

2002-01-01

7

Liquid phase adsorption of Crystal violet onto activated carbons derived from male flowers of coconut tree  

Microsoft Academic Search

Adsorption of Crystal violet, a basic dye onto phosphoric and sulphuric acid activated carbons (PAAC and SAAC), prepared from male flowers coconut tree has been investigated. Equilibrium data were successfully applied to study the kinetics and mechanism of adsorption of dye onto both the carbons. The kinetics of adsorption was found to be pseudo second order with regard to intraparticle

S. Senthilkumaar; P. Kalaamani; C. V. Subburaam

2006-01-01

8

Liquid-phase adsorption: Characterization and use of activated carbon prepared from diosgenin production residue  

Microsoft Academic Search

The adsorption behavior of activated carbon (AC) prepared from the residue of diosgenin by-product was characterized. The adsorption capacities of AC such as iodine, phenol and methylene blue (MB) are 933.28, 145.38 and 165mg\\/g, respectively. The results of MP analysis and BJH method show AC has developed micropore and mesopore volumes, which are 0.1621 and 0.2623cm3\\/g respectively, with the mean

Caixiang Zhang; Yanxin Wang; Xifeng Yan

2006-01-01

9

Liquid phase adsorption of Crystal violet onto activated carbons derived from male flowers of coconut tree.  

PubMed

Adsorption of Crystal violet, a basic dye onto phosphoric and sulphuric acid activated carbons (PAAC and SAAC), prepared from male flowers coconut tree has been investigated. Equilibrium data were successfully applied to study the kinetics and mechanism of adsorption of dye onto both the carbons. The kinetics of adsorption was found to be pseudo second order with regard to intraparticle diffusion. The pseudo second order is further supported by the Elovich model, which in turn intensifies the fact of chemisorption of dye onto both the carbons. Quantitative removal of dye at higher initial pH of dye solution reveals the basic nature of the Crystal violet and acidic nature of the activated carbons. Influence of temperature on the removal of dye from aqueous solution shows the feasibility of adsorption and its endothermic nature. Mass transfer studies were also carried out. The adsorption capacities of both the carbons were found to be 60.42 and 85.84 mg/g for PAAC and SAAC, respectively. Langmuir's isotherm data were used to design single-stage batch adsorption model. PMID:16675107

Senthilkumaar, S; Kalaamani, P; Subburaam, C V

2006-08-25

10

Liquid Phase Heating Systems  

E-print Network

Liquid phase heating systems involve sensible heat transfer in a closed loop wherein a pumped fluid's temperature is raised in a heater, then lowered in a heat user and returned for reheating. No formation and condensation of vapor occurs. High...

Mordt, E. H.

1979-01-01

11

In-situ activation of CuO/ZnO/Al.sub.2 O.sub.3 catalysts in the liquid phase  

DOEpatents

The present invention relates to a method of activation of a CuO/ZnO/Al.sub.2 O.sub.3 catalyst slurried in a chemically inert liquid. Successful activation of the catalyst requires the use of a process in which the temperature of the system at any time is not allowed to exceed a certain critical value, which is a function of the specific hydrogen uptake of the catalyst at that same time. This process is especially critical for activating highly concentrated catalyst slurries, typically 25 to 50 wt %. Activation of slurries of CuO/ZnO/Al.sub.2 O.sub.3 catalyst is useful in carrying out the liquid phase methanol or the liquid phase shift reactions.

Brown, Dennis M. (Allentown, PA); Hsiung, Thomas H. (Emmaus, PA); Rao, Pradip (Allentown, PA); Roberts, George W. (Emmaus, PA)

1989-01-01

12

Palladium supported on filamentous active carbon as effective catalyst for liquid-phase hydrogenation of 2-butyne-1,4-diol to 2-butene-1,4-diol  

Microsoft Academic Search

Structured palladium catalysts suitable for three-phase reactions have been developed based on woven fabrics of active carbon fibres (ACF) as the catalytic supports. The Pd\\/ACF were tested in liquid-phase hydrogenation of 2-butyne-1,4-diol showing a selectivity towards 2-butene-1,4-diol up to 97% at conversions up to 80%. The catalyst multiple reuse with stable activity\\/selectivity in a batch reactor was also demonstrated. The

E Joannet; C Horny; L Kiwi-Minsker; A Renken

2002-01-01

13

CATALYST ACTIVITY MAINTENANCE FOR THE LIQUID PHASE SYNTHESIS GAS-TO-DIMETHYL ETHER PROCESS PART II: DEVELOPMENT OF ALUMINUM PHOSPHATE AS THE DEHYDRATION CATALYST FOR THE SINGLE-STEP LIQUID PHASE SYNGAS-TO-DME PROCESS  

SciTech Connect

At the heart of the single-step liquid phase syngas-to-DME process (LPDME{trademark}) is a catalyst system that can be active as well as stable. In the Alternative Fuels I program, a dual-catalyst system containing a Cu-based commercial methanol synthesis catalyst (BASF S3-86) and a commercial dehydration material ({gamma}-alumina) was demonstrated. It provided the productivity and selectivity expected from the LPDME process. However, the catalyst system deactivated too rapidly to warrant a viable commercial process [1]. The mechanistic investigation in the early part of the DOE's Alternative Fuels II program revealed that the accelerated catalyst deactivation under LPDME conditions is due to detrimental interaction between the methanol synthesis catalyst and methanol dehydration catalyst [2,3]. The interaction was attributed to migration of Cu- and/or Zn-containing species from the synthesis catalyst to the dehydration catalyst. Identification of a dehydration catalyst that did not lead to this detrimental interaction while retaining adequate dehydration activity was elusive. Twenty-nine different dehydration materials were tested, but none showed the desired performance [2]. The search came to a turning point when aluminum phosphate was tested. This amorphous material is prepared by precipitating a solution containing Al(NO{sub 3}){sub 3} and H{sub 3}PO{sub 4} with NH{sub 4}OH, followed by washing, drying and calcination. The aluminum phosphate catalyst has adequate dehydration activity and good stability. It can co-exist with the Cu-based methanol synthesis catalyst without negatively affecting the latter catalyst's stability. This report documents the details of the development of this catalyst. These include initial leads, efforts in improving activity and stability, investigation and development of the best preparation parameters and procedures, mechanistic understanding and resulting preparation guidelines, and the accomplishments of this work.

Xiang-Dong Peng

2002-05-01

14

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

to estimate the gas/liquid mass transfer coefficient which was determined to be 0.14 sec-1 at 1000 rpm which ensured operation outside the diffusion limited region. Inerts such as N2 and CO2 can be used to mitigate the flammability envelope of these highly...

Ghanta, Madhav

2008-01-01

15

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)

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.

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

2011-07-01

16

Liquid Phase Miscibility Gap Materials  

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

17

Liquid Phase Sintering  

NASA Technical Reports Server (NTRS)

Industry spends billions of dollars each year on machine tools to manufacture products out of metal. This includes tools for cutting every kind of metal part from engine blocks to Shuttle main engine components. Cutting tool tips often break because of weak spots or defects in their composition. Based on a new concept called defect trapping, space offers a novel environment to study defect formation in molten metal materials as they solidify. After the return of these materials from space, researchers can evaluate the source of the defect and seek ways to eliminate them in products prepared on Earth. A widely used process for cutting tip manufacturing is liquid phase sintering. Compared to Earth-sintered samples which slump due to buoyancy induced by gravity, space samples are uniformly shaped and defects remain where they are formed. By studying metals sintered in space the US tool industry can potentially enhance its worldwide competitiveness. The Consortium for Materials Development in Space along with Wyle Labs, Teledyne Advanced Materials, and McDornell Douglas have conducted experiments in space.

2004-01-01

18

Activity of Some Glycolysis Enzymes in the Liquid Phase of Tissue Cultures Infected with Venezuelan Equine Encephalomyelitis Virus.  

National Technical Information Service (NTIS)

The reproduction of Venezuelan equine encephalitis virus in cultures of chick and human embryo fibroblasts is accompanied by changes in the activity of some enzymes of carbohydrate metabolism (glucosophosphatisomerase, aldolase, and lactatedehydrogenase)....

E. A. Peshkova, T. L. Miryutova

1972-01-01

19

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

NASA Astrophysics Data System (ADS)

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

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

20

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

PubMed

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. PMID:25188584

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

21

A thermodynamic model of mixed organic-inorganic aerosols to predict activity coefficients  

NASA Astrophysics Data System (ADS)

Tropospheric aerosols contain mixtures of inorganic salts, acids, water, and a large variety of organic compounds. Interactions between these substances in liquid mixtures lead to discrepancies from ideal thermodynamic behaviour. By means of activity coefficients, non-ideal behaviour can be taken into account. We present here a thermodynamic model named AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients) that is able to calculate activity coefficients covering inorganic, organic, and organic-inorganic interactions in aqueous solutions over a wide concentration range. This model is based on the activity coefficient model LIFAC by Yan et al. (1999) that we modified and reparametrised to better describe atmospherically relevant conditions and mixture compositions. Focusing on atmospheric applications we considered H+, Li+, Na+, K+, NH4+, Mg2+, Ca2+, Cl-, Br-, NO3-, HSO4-, and SO42- as cations and anions and a wide range of alcohols/polyols composed of the functional groups CHn and OH as organic compounds. With AIOMFAC, the activities of the components within an aqueous electrolyte solution are well represented up to high ionic strength. Most notably, a semi-empirical middle-range parametrisation of direct organic-inorganic interactions in alcohol + water + salt solutions strongly improves the agreement between experimental and modelled activity coefficients. At room temperature, this novel thermodynamic model offers the possibility to compute equilibrium relative humidities, gas/particle partitioning and liquid-liquid phase separations with high accuracy. In further studies, other organic functional groups will be introduced. The model framework is not restricted to specific ions or organic compounds and is therefore also applicable for other research topics.

Zuend, A.; Marcolli, C.; Luo, B. P.; Peter, Th.

2008-03-01

22

A thermodynamic model of mixed organic-inorganic aerosols to predict activity coefficients  

NASA Astrophysics Data System (ADS)

Tropospheric aerosols contain mixtures of inorganic salts, acids, water, and a large variety of organic compounds. Interactions between these substances in liquid mixtures lead to discrepancies from ideal thermodynamic behaviour. By means of activity coefficients, non-ideal behaviour can be taken into account. We present here a thermodynamic model named AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients) that is able to calculate activity coefficients covering inorganic, organic, and organic-inorganic interactions in aqueous solutions over a wide concentration range. This model is based on the activity coefficient model LIFAC by Yan et al. (1999) that we modified and reparametrised to better describe atmospherically relevant conditions and mixture compositions. Focusing on atmospheric applications we considered H+, Li+, Na+, K+, NH+4, Mg2+, Ca2+, Cl-, Br-, NO-3, HSO-4, and SO2-4 as cations and anions and a wide range of alcohols/polyols composed of the functional groups CHn and OH as organic compounds. With AIOMFAC, the activities of the components within an aqueous electrolyte solution are well represented up to high ionic strength. Most notably, a semi-empirical middle-range parametrisation of direct organic-inorganic interactions in alcohol+water+salt solutions strongly improves the agreement between experimental and modelled activity coefficients. At room temperature, this novel thermodynamic model offers the possibility to compute equilibrium relative humidities, gas/particle partitioning and liquid-liquid phase separations with high accuracy. In further studies, other organic functional groups will be introduced. The model framework is not restricted to specific ions or organic compounds and is therefore also applicable for other research topics.

Zuend, A.; Marcolli, C.; Luo, B. P.; Peter, T.

2008-08-01

23

Preparation and antibacterial activities of Ag-doped SiO 2 –TiO 2 composite films by liquid phase deposition (LPD) method  

Microsoft Academic Search

In the present study, Ag\\/SiO2–TiO2 thin films on ceramic tiles with glazed surface were successfully prepared by a liquid phase deposition method (LPD) at a\\u000a low temperature. The Ag\\/SiO2–TiO2 thin films obtained were homogenous, well adhered and colored by interference of reflected light. The films were characterized\\u000a by scanning electron microscopy and X-ray diffraction. From these analysis data, it was

Bo Sun; Shu-Qing Sun; Ting Li; Wen-Qin Zhang

2007-01-01

24

Mean activity coefficient of electrolyte solutions.  

PubMed

In this paper, we deal with the mean activity coefficient, gamma, of electrolyte solutions. The case gamma < or = 1 is investigated. As is generally recognized, the most accepted models (specific ion interaction/Pitzer theory) have the disadvantage of the dependence on semiempirical parameters. These are not directly accessible from experimental measurements, but can only be estimated by means of best-fitting numerical techniques from experimental data. In the general context of research devoted to the achievement of some reduction of complexity, we propose a model of electrolyte solution that allows us to calculate gamma without using fitting parameters where the (upper) concentration exists at which the electrolyte solution exhibits gamma = 1 (molality scale). In the remaining cases, we show that a unique parameter is required, that is, the concentration that should ideally give gamma = 1 for the electrolyte. Compared to other models that do not require adjustable parameters, the present one is generally applicable over a wider range of concentrations; moreover, it does not impose any restriction on the ion-size variations. Our model follows a pseudolattice approach, starting from the primitive idea of a disordered lattice of solute ions within a continuous solvent at extremely dilute solutions and coming to a disordered lattice of local arrangements of both solute ions and solvent dipoles at higher concentrations. Compared to other theories based on lattice models, this work stresses the role of statistical deviations from any time-averaged (lattice) configuration. All formulas in this paper are applied for 1:1, 2:2, 1:2, and 2:1 aqueous electrolytes at 25 degrees C. PMID:17388469

Moggia, Elsa; Bianco, Bruno

2007-03-29

25

Liquid-phase chromatography detector  

DOEpatents

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

Voigtman, Edward G. (Gainesville, FL); Winefordner, James D. (Gainesville, FL); Jurgensen, Arthur R. (Gainesville, FL)

1983-01-01

26

Liquid-phase chromatography detector  

DOEpatents

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

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

1983-11-08

27

Transient liquid phase ceramic bonding  

DOEpatents

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.

Glaeser, Andreas M. (Berkeley, CA)

1994-01-01

28

Liquid phase sintering in microgravity  

NASA Astrophysics Data System (ADS)

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.

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

29

Liquid phase sintering of silicon carbide  

DOEpatents

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.

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

1989-05-09

30

Liquid phase sintering of silicon carbide  

DOEpatents

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

Cutler, Raymond A. (Bountiful, UT); Virkar, Anil V. (Salt Lake City, UT); Hurford, Andrew C. (Salt Lake City, UT)

1989-01-01

31

Kinetics of heterogeneously catalyzed tert-amyl methyl ether reactions in the liquid phase  

SciTech Connect

The kinetics of tert-amyl methyl ether (TAME, 2-methoxy-2-methylbutane) reactions was investigated using a commercial ion exchange resin (Amberlyst 16) as catalyst at temperatures between 324 and 354 K. The rates of reaction were determined experimentally in the liquid phase in a continuous stirred tank reactor at a pressure of 0.8 MPa. Kinetic equations derived for three different mechanisms were compared. In the forward reaction the adsorbed methanol reacted with isoamylene (2-methyl-l-butene or 2-methyl-2-butene) striking from the bulk liquid phase, and in the splitting reaction the adsorbed ether split to alcohol and isoamylene. The kinetic equations were written in terms of activities, and the activity coefficients were calculated by the UNIQUAC method. The activation energy was determined to be 95 kJ/mol for the splitting reaction of TAME to 2-methyl-l-butene and methanol and 100 kJ/mol for the splitting reaction of TAME to 2-methyl-2-butene and methanol.

Rihko, L.K.; Krause, A.O.I. [Helsinki Univ. of Technology, Espoo (Finland). Lab. of Industrial Chemistry

1995-04-01

32

Electrolyte Solutions: Activity Coefficients and Debye-Huckel Chemistry 243  

E-print Network

Electrolyte Solutions: Activity Coefficients and Debye-Huckel Theory Chemistry 243 David Ronis McGill University To understand the thermodynamics of electrolyte solutions, we have to understand how nature tries for the chemical potentials and activities. Consider the electrolyte dissociation Az+ + Bz- - + Az+ + - Bz- , (1

Ronis, David M.

33

Infinite dilution activity coefficients of apple juice aroma compounds  

Microsoft Academic Search

An apparatus based on the inert gas stripping method was assembled for measuring infinite dilution activity coefficients, ??, of 15 apple juice aroma compounds in aqueous solutions. Values were estimated using the UNIFAC model and compared with experimental results; differences ranged from ?80 to 118% with an average of 48% for the absolute values of the differences. Values predicted with

Martin F. Sancho; M. A. Rao; D. L. Downing

1997-01-01

34

Binary Solid-Liquid Phase Equilibria  

ERIC Educational Resources Information Center

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)

Ellison, Herbert R.

1978-01-01

35

On liquid phases in cometary nuclei  

NASA Astrophysics Data System (ADS)

In this paper we review the relevant literature and investigate conditions likely to lead to melting of H2O ice, methanol (CH3OH) ice, ethane (C2H6) ice and other volatile ices in cometary nuclei. On the basis of a heat balance model which takes account of volatiles loss, we predict the formation of occasional aqueous and hydrocarbon liquid phases in subsurface regions at heliocentric distances, rh of 1-3 AU, and 5-12 AU, respectively. Low triple-point temperatures and low vapour pressures of C2H6, C3H8, and some higher-order alkanes and alkenes, favour liquid phase formation in cometary bodies at high rh. Microporosity and the formation of a stabilization crust occluding the escape of volatiles facilitate liquid-phase formation. Characteristics of the near-surface which favour subsurface melting include; low effective surface emissivity (at low rh), high amorphous carbon content, average pore sizes of ˜10 ?m or less, presence of solutes (e.g. CH3OH), mixtures of C2-C6 hydrocarbons (for melting at high rh), diurnal thermal cycling, and slow rotation rate. Applying the principles of soil mechanics, capillary forces are shown to initiate pre-melting phenomena and subsequent melting, which is expected to impart considerable strength of ˜104 Pa in partially saturated layers, reducing porosity and permeability, enhancing thermal conductivity and heat transfer. Diurnal thermal cycling is expected to have a marked effect on the composition and distribution of H2O ice in the near-surface leading to frost heave-type phenomena even where little if any true melting occurs. Where melting does take place, capillary suction in the wetted zone has the potential to enhance heat transfer via capillary wetting in a low-gravity environment, and to modify surface topography creating relatively smooth flat-bottomed features, which have a tendency to be located within small depressions. An important aspect of the "wetted layer" model is the prediction that diurnal melt-freeze cycles alter the mixing ratio vs. depth of solutes present, or of other miscible components, largely through a process of fractional crystallization, but also potentially involving frost heave. Wetted layers are potentially durable and can involve significant mass transport of volatile materials in the near-surface, increasing in extent over many rotations of the nucleus prior to and just after perihelion passage, and causing stratification and trapping of the lowest-melting mixtures at depths of several metres. A possible mechanism for cometary outbursts is proposed involving a heat pulse reaching the liquid phase in the deepest wetted zone, leading to supersaturation and triggering the sudden release under pressure of dissolved gases, in particular CO2, CO, CH4 or N2, contained beneath a consolidated near-surface layer. This study indicates that liquid water can persist for long periods of time in the near-surface of some intermediate-sized bodies (102-103 km radius) within protoplanetary discs.

Miles, Richard; Faillace, George A.

2012-06-01

36

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

SciTech Connect

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.

None

1997-06-30

37

Transient liquid phase sintering conductive adhesives as solder replacements  

Microsoft Academic Search

New transient liquid phase sintering conductive adhesives, which have an interpenetrating polymer\\/metal network, have been developed to mitigate some of the deficiencies of standard particle-filled conductive adhesives. The metal network is formed in situ by a process known as transient liquid phase sintering (TLPS) and is mutually reinforcing with the polymer network. Bulk as well as interface electrical connections are

Catherine Gallagher; Goran Matijasevic; James F. Maguire

1997-01-01

38

Miniaturized sample preparation combined with liquid phase separations  

Microsoft Academic Search

Miniaturized sample preparation methods designed as the sample pretreatment for liquid phase separations, such as liquid chromatography, capillary electrophoresis and capillary electrochromatography, have been reviewed especially for the on-line coupling of the sample preparation process and the separation process. The development of the desorption interfaces for the effective combining of the sample preparation and subsequent liquid phase separations is briefly

Yoshihiro Saito; Kiyokatsu Jinno

2003-01-01

39

Transfer having a coupling coefficient higher than its active material  

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

40

Solder deposition for transient liquid phase (TLP)-bonding by MSIP-PVD-process  

Microsoft Academic Search

In different technical areas micro electro mechanical systems (MEMS) are in use today. The components of these MEMS. consist of various materials, which are joined together. To join materials like ceramics, plastics or metals to a hybrid MEMS. a low temperature joining process, e.g. transient liquid phase (TLP) or an active soft soldering process can be performed. In this article,

E. Lugscheider; K. Bobzin; A. Erdle

2003-01-01

41

Mixed Stationary Liquid Phases for Gas-Liquid Chromatography.  

ERIC Educational Resources Information Center

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)

Koury, Albert M.; Parcher, Jon F.

1979-01-01

42

Spontaneous liquid-liquid phase separation of water  

NASA Astrophysics Data System (ADS)

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

Yagasaki, Takuma; Matsumoto, Masakazu; Tanaka, Hideki

2014-02-01

43

Graphene via sonication assisted liquid-phase exfoliation.  

PubMed

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

Ciesielski, Artur; Samorì, Paolo

2014-01-01

44

Formation of liquid and solid products from liquid phase pyrolysis.  

PubMed

The aim of the present work was to improve the C:O ratio in biomass by preserving the lignin macrostructure of lignocellulosic feed. The intention of liquid phase pyrolysis is to liquefy biomass and prepare biomass for further upgrading steps like hydrogenation and deoxygenation. Pyrolysis was carried out in a non-aqueous liquid phase heat carrier. The process was carried out in a semi-batch reaction vessel under isothermal conditions at T=350°C, supported by a quench to stop reactions instantaneously in order to observe formation of solid intermediates. This pyrolysis system enables the observation of liquid and solid product formation. Transformation of biomass into biochar was analyzed by infrared spectroscopy and elemental analysis. Stable lignin structure throughout the whole transformation was confirmed. It was shown that the lignin frame in wood remains without substantial loss, while the major amount of carbohydrates is pyrolyzed during liquid phase pyrolysis at T=350°C. PMID:22989638

Schwaiger, N; Witek, V; Feiner, R; Pucher, H; Zahel, K; Pieber, A; Pucher, P; Ahn, E; Chernev, B; Schroettner, H; Wilhelm, P; Siebenhofer, M

2012-11-01

45

CELLULOSE EXTRACTION FROM PALM KERNEL CAKE USING LIQUID PHASE OXIDATION  

Microsoft Academic Search

Cellulose is widely used in many aspect and industries such as food industry, pharmaceutical, paint, polymers, and many more. Due to the increasing demand in the market, studies and work to produce cellulose are still rapidly developing. In this work, liquid phase oxidation was used to extract cellulose from palm kernel cake to separate hemicellulose, cellulose and lignin. The method

FARM YAN YAN; DUDUKU KRISHNIAH; MARIANI RAJIN; AWANG BONO

46

In situ monitoring of liquid phase electroepitaxial growth  

NASA Technical Reports Server (NTRS)

In situ monitoring of the layer thickness during liquid phase electroepitaxy (LPEE) was achieved with a submicron resolution through precise resistance measurements. The new approach to the study and control of LPEE was applied to growth of undoped and Ge-doped GaAs layers. The in situ determined growth kinetics was found to be in excellent agreement with theory.

Okamoto, A.; Isozumi, S.; Lagowski, J.; Gatos, H. C.

1982-01-01

47

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

SciTech Connect

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.

None

1997-09-30

48

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

SciTech Connect

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.

Miller, D G

2007-05-16

49

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

Microsoft Academic Search

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

Natalia Semagina

2009-01-01

50

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

51

Powder metallurgy: Solid and liquid phase sintering of copper  

NASA Technical Reports Server (NTRS)

Basic powder metallurgy (P/M) principles and techniques are presented in this laboratory experiment. A copper based system is used since it is relatively easy to work with and is commercially important. In addition to standard solid state sintering, small quantities of low melting metals such as tin, zinc, lead, and aluminum can be added to demonstrate liquid phase sintering and alloy formation. The Taguchi Method of experimental design was used to study the effect of particle size, pressing force, sintering temperature, and sintering time. These parameters can be easily changed to incorporate liquid phase sintering effects and some guidelines for such substitutions are presented. The experiment is typically carried out over a period of three weeks.

Sheldon, Rex; Weiser, Martin W.

1993-01-01

52

Liquid-phase sintering of iron aluminide-bonded ceramics  

SciTech Connect

Iron aluminide intermetallics exhibit excellent oxidation and sulfidation resistance and are therefore considered as the matrix in metal matrix composites, or the binder in hard metals or cermets. In this paper the authors discuss the processing and properties of liquid-phase sintered iron aluminide-bonded ceramics. It is found that ceramics such as TiB{sub 2}, ZrB{sub 2}, TiC, and WC may all be liquid phase-sintered. nearly complete densification is achieved for ceramic volume fractions ranging up to 60%. Depending on the composition, room temperature three point-bend strengths and fracture toughnesses reaching 1,500 MPa and 30 MPa m{sup 1/2}, respectively, have been found. Since the processing was carried out in a very simple manner, optimized processing is likely to result in further improvements.

Schneibel, J.H.; Carmichael, C.A. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

1995-12-31

53

Containerless Liquid-Phase Processing of Ceramic Materials  

NASA Technical Reports Server (NTRS)

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.

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

1996-01-01

54

Transient liquid phase (TLP) bonding for microsystem packaging applications  

Microsoft Academic Search

This paper explores the use of transient liquid phase bonding for microsystem packaging applications. Two types of bonds are demonstrated: a thin-film evaporated indium-gold bond and an electroplated nickel-tin bond. Both bonds are formed at 300°C for about 1.5 hours in a conventional wafer bonder. The wafers were heated to over 400 °C for more than an hour after bonding

Warren Welch; Junseok Chae; Sang-Hyun Lee; Navid Yazdi; Khalil Najafi

2005-01-01

55

Novelties of liquid–liquid–liquid phase transfer catalysis  

Microsoft Academic Search

Liquid–liquid–liquid phase transfer catalysis (L–L–L PTC) offers orders of magnitude intensification of rates of reaction and better selectivities than the biphasic PTC. The catalyst-rich middle phase is the main reaction phase. The etherification or alkoxylation of p-chloronitrobenzene (PCNB) was conducted by using alkanol and alkali instead of the metal alkoxide. A kinetic model is presented and validated.

G. D Yadav; Suguna S Naik

2001-01-01

56

Experimental (solid + liquid) or (liquid + liquid) phase equilibria of (amine + nitrile) binary mixtures  

Microsoft Academic Search

(Solid+liquid) phase diagrams have been determined for (hexylamine, or octylamine, or 1,3-diaminopropane+acetonitrile) mixtures. Simple eutectic systems have been observed in these mixtures. (Liquid+liquid) phase diagrams have been determined for (octylamine, or decylamine+propanenitrile, or +butanenitrile) mixtures. Mixtures with propanenitrile and butanenitrile show immiscibility in the liquid phase with an upper critical solution temperature, UCST. (Solid+liquid) phase diagrams have been correlated using

Urszula Doma?ska; Ma?gorzata Marciniak

2007-01-01

57

Modeling the solid-liquid phase transition in saturated triglycerides  

NASA Astrophysics Data System (ADS)

We investigated theoretically two competing published scenarios for the melting transition of the triglyceride trilaurin (TL): those of (1) Corkery et al. [Langmuir 23, 7241 (2007)], in which the average state of each TL molecule in the liquid phase is a discotic ``Y'' conformer whose three chains are dynamically twisted, with an average angle of ~120° between them, and those of (2) Cebula et al. [J. Am. Oil Chem. Soc. 69, 130 (1992)], in which the liquid-state conformation of the TL molecule in the liquid phase is a nematic h*-conformer whose three chains are in a modified ``chair'' conformation. We developed two competing models for the two scenarios, in which TL molecules are in a nematic compact-chair (or ``h'') conformation, with extended, possibly all-trans, chains at low-temperatures, and in either a Y conformation or an h* conformation in the liquid state at temperatures higher than the phase-transition temperature, T*=319 K. We defined an h-Y model as a realization of the proposal of Corkery et al. [Langmuir 23, 7241 (2007)], and explored its predictions by mapping it onto an Ising model in a temperature-dependent field, performing a mean-field approximation, and calculating the transition enthalpy ?H. We found that the most plausible realization of the h-Y model, as applied to the solid-liquid phase transition in TL, and likely to all saturated triglycerides, gave a value of ?H in reasonable agreement with the experiment. We then defined an alternative h-h* model as a realization of the proposal of Cebula et al. [J. Am. Oil Chem. Soc. 69, 130 (1992)], in which the liquid phase exhibits an average symmetry breaking similar to an h conformation, but with twisted chains, to see whether it could describe the TL phase transition. The h-h* model gave a value of ?H that was too small by a factor of ~3-4. We also predicted the temperature dependence of the 1132 cm-1 Raman band for both models, and performed measurements of the ratios of three TL Raman bands in the temperature range of -20 °C<=T<=90 °C. The experimental results were in accord with the predictions of the h-Y model and support the proposal of Corkery et al. [Langmuir 23, 7241 (2007)] that the liquid state is made up of molecules that are each, on average, in a Y conformation. Finally, we carried out computer simulations of minimal-model TLs in the liquid phase, and concluded that although the individual TL molecules are, on average, Y conformers, long-range discotic order is unlikely to exist.

Pink, David A.; Hanna, Charles B.; Sandt, Christophe; MacDonald, Adam J.; MacEachern, Ronald; Corkery, Robert; Rousseau, Dérick

2010-02-01

58

Coefficients for Active Transport and Thermogenesis of Ca2 Signe Kjelstrup,* Daniel Barragan, and Dick Bedeaux  

E-print Network

Coefficients for Active Transport and Thermogenesis of Ca2þ -ATPase Isoforms Signe Kjelstrup muscle is higher than in brown adipose tissue. The thermogenesis ratio is high in both white muscle and brown adipose tissue, in agreement with a specific role in nonshivering thermogenesis. Other isoforms do

Kjelstrup, Signe

59

Prediction of Activity Coefficients of Electrolytes in Aqueous Solutions at High Temperatures  

E-print Network

Prediction of Activity Coefficients of Electrolytes in Aqueous Solutions at High Temperatures Xiaohua Lu, Luzheng Zhang, Yanru Wang, and Jun Shi Nanjing University of Chemical Technology, Nanjing solutions containing mixed electrolytes (Lu and Maurer, 1993) is extended from 298 K to temperatures up

Zhang, Luzheng

60

Chemistry World (suppl.) Vol. 37, 61 (1996). Determination of Activity Coefficients of the Systems  

E-print Network

to the system HCl-NH4Cl-H2O using the following cell with ion-selective electrodes (ISEs) pH-glass electrode from experimental measurements. Key Words: activity coefficient, electrolyte solution, ion-selective electrode, and Pitzer equation #12;#12;#12;#12;

Zhang, Luzheng

61

Activity coefficients of bicarbonate, carbonate and calcium ions in sea water  

Microsoft Academic Search

Measurements of pH of sea water samples equilibrated with known partial pressures of CO 2 and with calcite and aragonite have enabled the determination of molal activity coefficient for bicarbonate, carbonate, and calcium ions in two sea water samples at 25°C and 1 atm total pressure. Results are: For standard artificial sea water (chlorinity = 19.0 , titration alkalinity =

Robert A. Berner

1965-01-01

62

Measurement of activity coefficients of mixtures by head-space gas chromatography: general procedure.  

PubMed

Head-space gas chromatography (HS-GC) is an applicable method to perform vapor-liquid equilibrium measurements and determine activity coefficients. However, the reproducibility of the data may be conditioned by the experimental procedure concerning to the automated pressure-balanced system. The study developed in this work shows that a minimum volume of liquid in the vial is necessary to ensure the reliability of the activity coefficients since it may become a parameter that influences the magnitude of the peak areas: the helium introduced during the pressurization step may produce significant variations of the results when too small volume of liquid is selected. The minimum volume required should thus be evaluated prior to obtain experimentally the concentration in the vapor phase and the activity coefficients. In this work, the mixture acetonitrile-toluene is taken as example, requiring a sample volume of more than 5mL (about more than 25% of the vial volume). The vapor-liquid equilibrium and activity coefficients of mixtures at different concentrations (0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 molar fraction) and four temperatures (35, 45, 55 and 70°C) have been determined. Relative standard deviations (RSD) lower than 5% have been obtained, indicating the good reproducibility of the method when a sample volume larger than 5mL is used. Finally, a general procedure to measure activity coefficients by means of pressure-balanced head-space gas chromatography is proposed. PMID:23809803

Luis, Patricia; Wouters, Christine; Van der Bruggen, Bart; Sandler, Stanley I

2013-08-01

63

Development of the active balancing device for high-speed spindle system using influence coefficients  

Microsoft Academic Search

A high-speed spindle can be very sensitive to rotating mass unbalance which has harmful effect on many types of rotating machinery. Therefore, the balancing procedure is certainly needed to reduce vibration in all high-speed rotating systems. In this study, an active balancing program using influence coefficient method and an active balancing device of an electro-magnetic type with both simple and

Jong-Duk Moon; Bong-Suk Kim; Soo-Hun Lee

2006-01-01

64

Coefficients for Active Transport and Thermogenesis of Ca2+-ATPase Isoforms  

PubMed Central

Coefficients for active transport of ions and heat in vesicles with Ca2+-ATPase from sarcoplasmic reticulum are defined in terms of a newly proposed thermodynamic theory and calculated using experiments reported in the literature. The coefficients characterize in a quantitative manner different performances of the enzyme isoforms. Four enzyme isoforms are examined, namely from white and red muscle tissue, from blood platelets, and from brown adipose mitochondria. The results indicate that the isoforms have a somewhat specialized function. White muscle tissue and brown adipose tissue have the same active transport coefficient ratio, but the activity level of the enzyme in white muscle is higher than in brown adipose tissue. The thermogenesis ratio is high in both white muscle and brown adipose tissue, in agreement with a specific role in nonshivering thermogenesis. Other isoforms do not have this ability to generate heat. A calcium-dependence of the coefficients is found, which can be understood as being in accordance with the role of this ion as a messenger in muscle contraction as well as in thermogenesis. The investigation points to new experiments related to structure as well as to function of the isoforms. PMID:19486662

Kjelstrup, Signe; Barragán, Daniel; Bedeaux, Dick

2009-01-01

65

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

SciTech Connect

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.

Not Available

1993-02-01

66

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

NASA Astrophysics Data System (ADS)

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

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

67

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

NASA Astrophysics Data System (ADS)

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

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

2011-09-01

68

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

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

69

Molecular radiotherapy: The NUKFIT software for calculating the time-integrated activity coefficient  

SciTech Connect

Purpose: Calculation of the time-integrated activity coefficient (residence time) is a crucial step in dosimetry for molecular radiotherapy. However, available software is deficient in that it is either not tailored for the use in molecular radiotherapy and/or does not include all required estimation methods. The aim of this work was therefore the development and programming of an algorithm which allows for an objective and reproducible determination of the time-integrated activity coefficient and its standard error.Methods: The algorithm includes the selection of a set of fitting functions from predefined sums of exponentials and the choice of an error model for the used data. To estimate the values of the adjustable parameters an objective function, depending on the data, the parameters of the error model, the fitting function and (if required and available) Bayesian information, is minimized. To increase reproducibility and user-friendliness the starting values are automatically determined using a combination of curve stripping and random search. Visual inspection, the coefficient of determination, the standard error of the fitted parameters, and the correlation matrix are provided to evaluate the quality of the fit. The functions which are most supported by the data are determined using the corrected Akaike information criterion. The time-integrated activity coefficient is estimated by analytically integrating the fitted functions. Its standard error is determined assuming Gaussian error propagation. The software was implemented using MATLAB.Results: To validate the proper implementation of the objective function and the fit functions, the results of NUKFIT and SAAM numerical, a commercially available software tool, were compared. The automatic search for starting values was successfully tested for reproducibility. The quality criteria applied in conjunction with the Akaike information criterion allowed the selection of suitable functions. Function fit parameters and their standard error estimated by using SAAM numerical and NUKFIT showed differences of <1%. The differences for the time-integrated activity coefficients were also <1% (standard error between 0.4% and 3%). In general, the application of the software is user-friendly and the results are mathematically correct and reproducible. An application of NUKFIT is presented for three different clinical examples.Conclusions: The software tool with its underlying methodology can be employed to objectively and reproducibly estimate the time integrated activity coefficient and its standard error for most time activity data in molecular radiotherapy.

Kletting, P.; Schimmel, S.; Luster, M. [Klinik für Nuklearmedizin, Universität Ulm, Ulm 89081 (Germany)] [Klinik für Nuklearmedizin, Universität Ulm, Ulm 89081 (Germany); Kestler, H. A. [Research Group Bioinformatics and Systems Biology, Institut für Neuroinformatik, Universität Ulm, Ulm 89081 (Germany)] [Research Group Bioinformatics and Systems Biology, Institut für Neuroinformatik, Universität Ulm, Ulm 89081 (Germany); Hänscheid, H.; Fernández, M.; Lassmann, M. [Klinik für Nuklearmedizin, Universität Würzburg, Würzburg 97080 (Germany)] [Klinik für Nuklearmedizin, Universität Würzburg, Würzburg 97080 (Germany); Bröer, J. H.; Nosske, D. [Bundesamt für Strahlenschutz, Fachbereich Strahlenschutz und Gesundheit, Oberschleißheim 85764 (Germany)] [Bundesamt für Strahlenschutz, Fachbereich Strahlenschutz und Gesundheit, Oberschleißheim 85764 (Germany); Glatting, G. [Medical Radiation Physics/Radiation Protection, Medical Faculty Mannheim, Heidelberg University, Mannheim 68167 (Germany)] [Medical Radiation Physics/Radiation Protection, Medical Faculty Mannheim, Heidelberg University, Mannheim 68167 (Germany)

2013-10-15

70

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

SciTech Connect

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.

NONE

1996-05-01

71

Storing solar energy by liquid phase Diels-Alder reactions  

SciTech Connect

Using chemical reactions to store energy is not a new concept. But the idea of using chemical reactions entirely in the liquid phase at low temperatures for relatively small scale storage applications, i.e., for space heating, is relatively undeveloped. In this study, the method of how chemical reactions could be used to store energy without generation and storage of new phases is described. Criteria a reaction must satisfy to successfully store energy are presented and several Diels-Alder reactions are evaluated in terms of these criteria. All this time, no reactions have been identified that meet all the criteria. 6 refs.

Sparks, B.G.; Thompson, P.F.; Poling, B.E.

1981-01-01

72

Reaction calorimetry study of the liquid-phase synthesis of tert-butyl methyl ether  

SciTech Connect

The liquid-phase addition of methanol to isobutene to give tert-butyl methyl ether (MTBE) on the ion-exchange resin Lewatit K2631 has been studied in a calorimetric reactor. Heat capacity of MTBE and enthalpy of the MTBE synthesis reaction in the temperature range 312--333 K have been determined. MTBE heat capacity in the liquid phase has been found to obey the equation c[sub P] (J/mol[center dot]K) = 472.34 [minus] 2.468(T/K) + 0.005071(T/K)[sup 2]. At 298 K the standard molar reaction enthalpy is [Delta]H[degree] = [minus]33.8 kJ/mol. A method to estimate apparent activation energies from heat flow rate in a given reaction has been developed and proved to be valid for the MTBE synthesis. Using this method, an apparent activation energy of 91.1--95.2 kJ/mol is calculated. A [minus]3.8 kJ/mol value has been found for the adsorption enthalpy of methanol on the ion-exchange resin Lewatit K2631 by a combination of reaction calorimetry and thermogravimetry. This allows the calculation of an activation energy on the gel phase of the resin of 91 kJ/mol.

Sola, L.; Pericas, M.A.; Cunill, F.; Iborra, M. (Univ. de Barcelona (Spain). Dept. d'Enginyeria Quimica)

1994-11-01

73

A Computationally Efficient Model for Multicomponent Activity Coefficients in Aqueous Solutions  

SciTech Connect

Three-dimensional models of atmospheric inorganic aerosols need an accurate yet computationally efficient parameterization of activity coefficients, which are repeatedly updated in aerosol phase equilibrium and gas-aerosol partitioning calculations. In this paper, we describe the development and evaluation of a new mixing rule for estimating multicomponent activity coefficients of electrolytes typically found in atmospheric aerosol systems containing H(+), NH4(+), Na(+), Ca(2+), SO4(2-), HSO4(-), NO3(-), and Cl(-) ions. The new mixing rule, called MTEM (Multicomponent Taylor Expansion Model), estimates the mean activity coefficient of an electrolyte A in a multicomponent solution from a linear combination of its values in ternary solutions of A-A-H2O, A-B-H2O, A-C-H2O, etc., as the amount of A approaches zero in the mixture at the solution water activity, aw, assuming aw is equal to the ambient relative humidity. Predictions from MTEM are found to be within a factor of 0.8 to 1.25 of the comprehensive Pitzer-Simonson-Clegg (PSC) model over a wide range of water activities, and are shown to be significantly more accurate than the widely used Kusik and Meissner (KM) mixing rule, especially for electrolytes in sulfate-rich aerosol systems and for relatively minor but important aerosol components such as HNO3 and HCl acids. Because the ternary activity coefficient polynomials are parameterized as a function of aw, they have to be computed only once at every grid point at the beginning of every 3-D model time step as opposed to repeated evaluations of the ionic strength dependent binary activity coefficient polynomials in the KM method. Additionally, MTEM also yields a non-iterative solution of the bisulfate ion dissociation in sulfate-rich systems, which is a major computational advantage over other iterative methods as will be shown by a comparison of the CPU time requirements of MTEM for both sulfate-poor and sulfate-rich systems relative to other methods.

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

2004-10-04

74

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

Microsoft Academic Search

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.

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

2009-01-01

75

Predicting the Activity Coefficients of Free-Solvent for Concentrated Globular Protein Solutions Using Independently Determined Physical Parameters  

PubMed Central

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

McBride, Devin W.; Rodgers, Victor G. J.

2013-01-01

76

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

PubMed

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

McBride, Devin W; Rodgers, Victor G J

2013-01-01

77

TiO 2 photocatalytic oxidation: I. Photocatalysts for liquid-phase and gas-phase processes and the photocatalytic degradation of chemical warfare agent simulants in a liquid phase  

Microsoft Academic Search

The results of studies on the effect of the preparation procedure on the properties of TiO2-based photocatalysts and the kinetics and mechanism of the photocatalytic oxidation of organic water pollutants are surveyed. The effects of calcination temperature, surface modification with platinum, and acid-base treatment of the surface of titanium dioxide on its activity in model gas-phase and liquid-phase reactions are

A. V. Vorontsov; D. V. Kozlov; P. G. Smirniotis; V. N. Parmon

2005-01-01

78

Electrochemical characterization of liquid phase exfoliated two-dimensional layers of molybdenum disulfide.  

PubMed

We report on the electrochemical charge storage behavior of few-layered flakes of molybdenum disulfide (MoS2) obtained by liquid phase exfoliation of bulk MoS2 powder in 1-dodecyl-2-pyrrolidinone. The specific capacitances of the exfoliated flakes obtained using a 6 M KOH aqueous solution as an electrolyte were found to be an order of magnitude higher than those of bulk MoS2 (?0.5 and ?2 mF cm(-2) for bulk and exfoliated MoS2 electrodes, respectively). The exfoliated MoS2 flakes also showed significant charge storage in different electrolytes, such as organic solvents [1 M tetraethylammonium tetrafluoroborate in propylene carbonate (Et4NBF4 in PC)] and ionic liquids [1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6)]. The values of specific capacitances obtained using Et4NBF4 in PC and BMIM-PF6 were ?2.25 and ?2.4 mF cm(-2), respectively. An analysis of electrochemical impedance spectroscopy using an equivalent circuit modeling was performed to understand the charge storage mechanism of these exfoliated MoS2 flakes using different electrolytes. Our findings indicate that liquid phase exfoliation methods can be used to produce large quantities of electrochemically active, two-dimensional layers of MoS2 and can act as an ideal material in several applications related to electrochemistry. PMID:24444714

Winchester, Andrew; Ghosh, Sujoy; Feng, Simin; Elias, Ana Laura; Mallouk, Tom; Terrones, Mauricio; Talapatra, Saikat

2014-02-12

79

A New Method for Multicomponent Activity Coefficients of Electrolytes in Aqueous Atmospheric Aerosols  

SciTech Connect

Three-dimensional models of atmospheric inorganic aerosols need an accurate yet computationally efficient parameterization of activity coefficients of various electrolytes in multicomponent aqueous solutions. This paper describes the development and application of a new mixing rule for calculating activity coefficients of electrolytes typically found in atmospheric aerosol systems containing H+, NH4+, Na+, Ca2+ SO42-, HSO4-, NO3-, and Cl- ions. The new mixing rule, called MTEM (Multicomponent Taylor Expansion Model), estimates the mean activity coefficient of an electrolyte in a multicomponent solution based on 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. The aerosol water content is calculated using the Zdanovskii-Stokes-Robinson method. For self-consistency, most of the MTEM and Zdanovskii-Stokes-Robinson parameters are derived using the comprehensive Pitzer-Simonson-Clegg model at 298.15 K. MTEM is evaluated for several multicomponent systems representing various continental and marine aerosols, and is contrasted against the mixing rule of Kusik and Meissner and the newer approach of Metzger et al. [2002]. Predictions of MTEM are found to be generally within a factor of 0.8 to 1.25 of the comprehensive Pitzer-Simonson-Clegg model, and are shown to be significantly more accurate than predictions of the other two methods. MTEM also yields a non-iterative solution of the bisulfate ion dissociation in sulfate-rich systems – a major computational advantage over other iterative methods. CPU time requirements of MTEM relative to other methods for sulfate-poor and sulfate-rich systems are also discussed.

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

2005-01-21

80

Kinetics of the liquid-phase hydrogenation of benzene and some monosubstituted alkylbenzenes over a nickel catalyst  

Microsoft Academic Search

The liquid-phase hydrogenation kinetics of benzene and three monosubstituted alkylbenzenes, toluene, ethylbenzene, and cumene, was determined in a semibatch reactor operating at hydrogen pressures of 20--40 atm and at temperatures of 95--125 C. Commercial preactivated catalyst particles of nickel-alumina were used in all experiments. The hydrogenation activity of the compounds decreased in the order benzene â« toluene > ethylbenzene >

S. Toppinen; T. Salmi; T. K. Rantakylae; J. Aittamaa

1996-01-01

81

Kinetics of p-xylene liquid-phase catalytic oxidation  

SciTech Connect

A semibatch gas-liquid reactor model based on a lumped kinetic scheme for the liquid-phase oxidation of p-xylene to p-toluic acid catalyzed by cobalt naphthenate is developed. The model accounts for the complex nature of the involved reaction network, as well as for the interphase and intraphase mass transport processes of both reactants and products. The model reliability is tested by comparison with suitable experimental data obtained in a semibatch oxidation reactor, where the role of the composition of both the gaseous and the liquid feed has been investigated. It is shown that the model describes the reactor behavior in any of the regimes which may prevail depending upon the operating conditions and the depletion of liquid reactants in time.

Cao, G.; Servida, A. (Univ. di Cagliari (Italy). Dipt. di Ingegneria Chimica e Materiali); Pisu, M. (Sviluppo e Studi Superiori in Sardegna, Cagliari (Italy). Centro di Ricerche); Morbidelli, M. (Politecnico di Milano (Italy). Dipt. di Chimica Fisica Applicata)

1994-07-01

82

Liquid phase stability under an extreme temperature gradient.  

PubMed

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

Liang, Zhi; Sasikumar, Kiran; Keblinski, Pawel

2013-11-27

83

Liquid-Phase Shear Horizontal Surface Acoustic Wave Immunosensor  

NASA Astrophysics Data System (ADS)

In this paper, we describe liquid-phase immunosensors based on shear horizontal surface acoustic waves (SH-SAWs), which can be directly dipped into a liquid. The sensor devices are fabricated using an SH-SAW delay line on quartz and LiTaO3 substrates, which is composed of a transmitting floating electrode unidirectional transducer (FEUDT), receiving FEUDT, and a biochemical reaction area between them. These FEUDTs are protected from liquids by a glass lid and epoxy walls, which are constructed using a photolithography technique. Therefore, the sensor devices can be directly dipped into a liquid and a liquid can be directly applied onto the surface of the sensor devices. In order to evaluate basic characteristics of the sensor devices, glycerol-water mixture liquids of different viscosities were used. For evaluations of their applicability to immunoassay, human serum albumin antigen-antibody reactions were investigated.

Takashi Kogai,; Naoyuki Yoshimura,; Toshimasa Mori,; Hiromi Yatsuda,

2010-07-01

84

Kinetics for etherification of sodium o-nitrophenoxide via third-liquid phase-transfer catalysis  

Microsoft Academic Search

The novel method for synthesizing o-nitrophenyl octyl ether from the etherification of sodium o-nitrophenoxide and 1-bromooctane was investigated via third-liquid phase-transfer catalysis (TLPTC). The volume of the third-liquid phase formed increases with increasing the amount of catalyst employed, and about 91.2% of tetrabutylammonium bromide (TBPB) was accumulated in the third-liquid phase by adding 0.07mol of NaOH, leading to a higher

Piao-Jen Lin; Hung-Ming Yang

2005-01-01

85

Partitioning of hydrogen peroxide between the gas and liquid phases in the presence of surfactant  

Microsoft Academic Search

Gas–liquid phase partitioning is a key physical property that can predict the environmental fate of a compound between two phases. Several environmental factors have been known to affect the gas–liquid phase partitioning. We investigated the influence of surfactant on the gas–liquid phase partitioning of hydrogen peroxide (H2O2). The surfactant used was ammonium perfluorooctanoate (APFO). H2O2 solution containing the surfactant was

Youn-Joo An; Ji Hoon Lee; Seung-Woo Jeong

2007-01-01

86

Electrochemical Characterization of Liquid Phase Exfoliated Two-Dimensional Layers of Molybdenum Disulfide  

E-print Network

to various physicochemical properties ranging from solid lubricants to catalysts. For example, crystals of Mo, liquid phase exfoliation, electrochemical, charge storage INTRODUCTION Molybdenum disulfide (MoS2

87

Solubility parameter and activity coefficient of HDEHP dimer in select organic diluents by vapor pressure osmometry  

SciTech Connect

A thorough understanding of the non-ideal behavior of the chemical components utilized in solvent extraction contributes to the success of any large-scale spent nuclear fuel treatment. To address this, our current work uses vapor pressure osmometry to characterize the non-ideal behavior of the solvent extraction agent di-(2-ethylhexyl) phosphoric acid (HDEHP), a common extractant in proposed separation schemes. Solubility parameters were fit to data on HDEHP at four temperatures using models based on Scatchard Hildebrand regular solution theory with Flory Huggins entropic corrections. The results are comparable but not identical to the activity coefficients from prior slope analysis in the literature. (authors)

Gray, M.; Nilsson, M. [University of California Irvine, 916 Engineering Tower, UC Irvine, Irvine, CA 92697-2575 (United States); Zalupski, P. [Idaho National Laboratory, 2525 Fremont Avenue, Idaho Falls, ID 83415 (United States)

2013-07-01

88

High temperature creep of SiC densified using a transient liquid phase  

SciTech Connect

Silicon carbide-based ceramics can be rapidly densified above approximately 1850 {degree}C due to a transient liquid phase resulting from the reaction between alumina and aluminum oxycarbides. The resulting ceramics are fine-grained, dense, and exhibit high strength at room temperature. SiC hot pressed at 1875 {degree}C for 10 min in Ar was subjected to creep deformation in bending at elevated temperatures between 1500 and 1650 {degree}C in Ar. Creep was thermally activated with an activation energy of 743 kJ/mol. Creep rates at 1575 {degree}C were between 10{sup {minus}9}/s and 10{sup {minus}7}/s at an applied stress between 38 and 200 MPa, respectively, resulting in a stress exponent of {approx}1.7.

Jou, Z.C.; Virkar, A.V. (Department of Materials Science and Engineering, The University of Utah, Salt Lake City, Utah (USA)); Cutler, R.A. (Ceramatec, Inc., 2425 South 900 West, Salt Lake City, Utah (USA))

1991-09-01

89

Novelties of reaction in the middle liquid phase in tri-liquid phase transfer catalysis: Kinetics of selective O-alkylation of vanillin with benzyl chloride  

Microsoft Academic Search

Reactions in three immiscible liquid phases (L–L–L) are attractive, and one of the phases can be the locale of reaction which will have a dramatic effect on product distribution in complex reactions. Thus, converting a bi-liquid system into a tri-liquid phase is of considerable scientific and commercial interest. 4-Benzyloxy-vanillin is used as a perfume and also as a starting material

Ganapati D. Yadav; Sharad V. Lande

2005-01-01

90

Commercial-Scale Demonstration of the Liquid Phase Methanol (LPMEOTH) Process  

SciTech Connect

The 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 LPMEOI-P Process Demonstration Unit was built at a site located at the Eastman coal-to-chemicals complex in Kingsport. During this quarter, initial planning and procurement work continued on the seven project sites which have been accepted for participation in the off-site, product-use test program. Approximately 12,000 gallons of fuel-grade methanol (98+ wt% methanol, 4 wt% water) produced during operation on carbon monoxide (CO)-rich syngas at the LPMEOW Demonstration Unit was loaded into trailers and shipped off-site for Mure product-use testing. At one of the projects, three buses have been tested on chemical-grade methanol and on fhel-grade methanol from the LPMEOW Demonstration Project. During the reporting period, planning for a proof-of-concept test run of the Liquid Phase Dimethyl Ether (LPDME~ Process at the Alternative Fuels Development Unit (AFDU) in LaPorte, TX continued. The commercial catalyst manufacturer (Calsicat) has prepared the first batch of dehydration catalyst in large-scale equipment. Air Products will test a sample of this material in the laboratory autoclave. 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 laborato~ autoclave), was monitored for the initial extended operation at the lower initial reactor operating temperature of 235oC. At this condition, the decrease in catalyst activity with time from the period 20 December 1997 through 27 January 1998 occurred at a rate of 1.0% per day, which represented a significant improvement over the 3.4Yi per day decline measured during the initial six weeks of operation in April and May of 1997. The deactivation rate also improved from the longer-term rate of 1.6% per day calculated throughout the summer and autumn of 1997.

None

1998-12-21

91

Glass and liquid phase diagram of a polyamorphic monatomic system  

NASA Astrophysics Data System (ADS)

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).

Reisman, Shaina; Giovambattista, Nicolas

2013-02-01

92

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

NASA Astrophysics Data System (ADS)

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.

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

2005-01-01

93

[Influence of human activities on groundwater environment based on coefficient variation method].  

PubMed

Groundwater system in the plain area of Beijing can be divided into six subsystems. Due to the different hydrogeological conditions of the subsystems, the degrees to which human activities affect the subsystems are also diverse. In order to evaluate the influence of human activities on each subsystem, the first and second aquifer with relatively poor water quality were chosen to be the evaluating positions, based on the data of groundwater sampled in September, 2011. With respect to human activities affect index such as total hardness, TDS, sulfate and ammonium, variation coefficient methods were used to calculate the weight of each index. Then scores were obtained for each index with national standard as reference, and superposition calculations were used to gain comprehensive scores, finally the groundwater quality conditions were evaluated. Contrast analyses were used to evaluate the incidence of human activities with groundwater subsystems as evaluation unit and water quality partitions as evaluation factors. The results indicate that the influence of human activities on the first aquifer is greater than that of the second aquifer, the Yongding river groundwater subsystems and the Chaobai river groundwater subsystems are affected more than other groundwater subsystems. PMID:23798103

Zhao, Wei; Lin, Jian; Wang, Shu-Fang; Liu, Ji-Lai; Chen, Zhong-Rong; Kou, Wen-Jie

2013-04-01

94

Ionic liquid-phase synthesis of 1,5-disubstituted 1,2,3-triazoles.  

PubMed

A simplified ionic liquid-phase synthesis of 1,5-disubstituted 1,2,3-triazole was developed. Nineteen 1,5-disubstituted 1,2,3-triazoles were successfully obtained by merely washing the ionic liquid phase with ether, thus avoiding the need for intermediate purification. PMID:25036551

Koguchi, Shinichi; Izawa, Kazuki

2014-08-11

95

Compaction process in liquid-phase sintering under pressure in the W--Ni system  

Microsoft Academic Search

S>The compaction process in liquid-phase sintering under pressure was ; studied in the system tungsten-copper. The effect of the applied pressure on the ; compaction is studied as dependent on the liquid phase content, sintering ; temperature, degree of solid phase wenting with liguid, and size of solid-phase ; particles. It is shown that a rise in the degree of

Yu. V. Naidich; I. A. Lavrinenko; V. A. Evdokimov

1974-01-01

96

Thermochemical analysis of the silicon carbide-alumina reaction with reference to liquid-phase sintering of silicon carbide  

NASA Technical Reports Server (NTRS)

The stabilities of different phases in the Si-Al-C-O system are calculated from thermodynamic considerations with the objective of identifying the liquid phases formed during sintering of SiC in the presence of Al2O3. It is shown that a liquid phase can form at the sintering temperatures by the reaction of SiC with Al2O3. Depending on the carbon activity, the liquid can be either of the following: Al2O3 + Al4C3, SiC + Al4C3, or molten aluminum. The stability of the aluminosilicate melts that can form by the reaction of Al2O3 with the surface silica layer on SiC powders is also evaluated. Several factors that influence liquid-phase sintering, such as the solubility of SiC in the melts and the generation of gases during sintering, are discussed. The results of the thermodynamic analysis are compared with the observed sintering behavior for SiC.

Misra, Ajay K.

1991-01-01

97

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

PubMed

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

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

2013-11-01

98

Liquid phase deposition synthesis of hexagonal molybdenum trioxide thin films  

SciTech Connect

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

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

99

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

NASA Astrophysics Data System (ADS)

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.

Whitsitt, Elizabeth A.

100

Pore metamorphosis during liquid phase sintering in microgravity  

NASA Astrophysics Data System (ADS)

This dissertation documents the pore metamorphosis in microgravity liquid phase sintered Co-Cu and Fe-Cu samples that have been successfully conducted on several sounding rocket flights, Space Shuttle missions and aboard the Mir Station. Pore filling and coarsening were found in most samples while pore breakup was also found in low liquid volume samples. Pores showed bifurcated behaviors based on their liquid volume fractions. These behaviors resulted from particle rearrangement, particle growth and volume diffusion that associated with interfacial energy differences, instabilities, and grain coarsening along the interface between phases. The mechanisms for pore breakup, pore coarsening and pore filling are discussed. An initiation mechanism induced by grain growth, capillary force and other weak forces is proposed and the results from theoretical analysis and CFD numerical simulation for pore breakup are presented. The microstructure evolutions of Co-Cu and Fe-Cu samples and the grain growth measurements that associated with pore morphological changes are also documented in this dissertation.

He, Yubin

101

Highly diastereoselective monoalkylation and Michael addition of N-(diphenylmethylene)glycinesultam under solid–liquid phase-transfer catalysis conditions using potassium carbonate as base  

Microsoft Academic Search

Treatment of a sultam-derived N-(diphenylmethylene)glycinate equivalent 1 with activated (allylic and propargylic) organic bromides and with Michael acceptors under solid–liquid phase-transfer catalysis conditions, using potassium carbonate as base, affords the monoalkylated compounds with high diastereoselectivity (>97% d.e.).

Anna López; Roser Pleixats

1998-01-01

102

Design and Fabrication of the First Commercial-Scale Liquid Phase Methanol (LPMEOH) Reactor  

SciTech Connect

The Liquid Phase Methanol (LPMEOHT) process uses a slurry bubble column reactor to convert synthesis gas (syngas), primarily a mixture of carbon monoxide and hydrogen, to methanol. Because of its superior heat management the process can utilize directly the carbon monoxide (CO)-rich syngas characteristic of the gasification of coal, petroleum coke, residual oil, wastes, or other hydrocarbon feedstocks. The LPMEOHM 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., a partnership between Air Products and Chemicals, Inc. and Eastman Chemical Company, to produce methanol from coal-derived syngas. Construction of the LPMEOH~ Process Demonstration Plant at Eastman's chemicals-from-coal complex in Kingsport was completed in January 1997. Following commissioning and shakedown activities, the fwst production of methanol from the facility occurred on April 2, 1997. Nameplate capacity of 260 short tons per day (TPD) was achieved on April 6, 1997, and production rates have exceeded 300 TPD of methanol at times. This report describes the design, fabrication, and installation of the Kingsport LPMEOEFM reactor, which is the first commercial-scale LPMEOEPM reaetor ever built. The vessel is 7.5 feet in diameter and 70 feet tall with design conditions of 1000 psig at 600 `F. These dimensions represent a significant scale-up from prior experience at the DOE-owned Alternative Fuels Development Unit in LaPorte, Texas, where 18-inch and 22-inch diameter reactors have been tested successfidly over thousands of hours. The biggest obstacles discovered during the scale- up, however, were encountered during fabrication of the vessel. The lessons learned during this process must be considered in tailoring the design for future sites, where the reactor dimensions may grow by yet another factor of two.

None

1998-12-21

103

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

PubMed Central

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

Larsson, Niklas; Otrembska, Paulina; Villar, Mercedes; Jonsson, Jan Ake

2011-01-01

104

Ionic liquid-based liquid-phase microextraction, a new sample enrichment procedure for liquid chromatography.  

PubMed

Room temperature ionic liquids (RTILs) were used as extraction solvent in liquid-phase microextraction (LPME) coupled with liquid chromatography. Using 1-hexyl-3-methylimidazolium hexafluorophosphate ([C6MIM][PF6]) as extraction solvent, some parameters related to LPME of 4-nonylphenol (4-NP) and 4-tert-octylphenol (4-t-OP) were optimized. Although [C6MIM][PF6] can suspend a much larger volume of drop on the needle of the microsyringe than the conventional solvents such as 1-octanol and carbon tetrachloride, the method sensitivity was analyte dependent because of the different partition coefficients and the relatively large viscosity of [C6MIM][PF6]. The proposed procedure has a detection limit and enrichment factor of 0.3 microg l(-1) and 163 for 4-NP, and 0.7 microg l(-1) and 130 for 4-t-OP, respectively. Aqueous samples including tap water, river water, and effluent from sewage treatment plant were analyzed by the proposed method and the recoveries at 10 microg l(-1) spiked level were in the range of 90-113%. PMID:14763740

Liu, Jing-fu; Chi, Yu-guang; Jiang, Gui-bin; Tai, Chao; Peng, Jin-feng; Hu, Jing-Tian

2004-02-13

105

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

PubMed

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

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

2005-07-15

106

Synthesis and Characterization of Ferroic and Multiferroic Nanostructures by Liquid Phase Deposition  

NASA Astrophysics Data System (ADS)

Magnetoelectric multiferroics have garnered an increasing interest in the past decade due to their unique properties and relevant applications in data storage, sensing and spintronics. A key requirement for the enhancement of the magnetoelectric effect at room temperature is the optimization of the interface between the constituting phases by designing nanocomposites with selectable topologies and variable chemical composition. In this research, the rational design of two-phase spinel-perovskite ceramic nanocomposites with two different geometries: coaxial nanostructures (1-D) and bilayered nanostructures (2-D), by a soft solution chemistry approach will be described. The liquid phase deposition (LPD) method is a simple and versatile route for the deposition of highly uniform spinel ferrite (MFe2O4) and/or titanium-based perovskite (BaTiO3, PbTiO3) by the controlled hydrolysis of metal fluoro-complexes at temperatures as low as 40°C. By designing a sequential deposition process, 1-D and 2-D magnetoelectric nanostructures were fabricated by filling perovskite nanotubes with the ferrite phase or depositing a ferrite layer on top of a perovskite thin film, respectively. The compositional and morphological characteristics of these highly uniform metal oxide nanostructures were investigated by X-ray diffraction (XRD), Raman spectroscopy, scanning probe microscopy (SPM) and electron microscopy (FE-SEM and TEM). The direct evidence of the stress mediated magnetoelectric coupling between the spinel and perovskite of the bilayered nanostructures was qualitatively studied by Raman spectroscopy. Additionally, the direct magnetoelectric effect in these 1-D and bilayered multiferroic nanocomposites was evaluated both quantitatively and qualitatively by using a novel magnetic field-assisted piezoelectric force microscopy (M-PFM) technique. The quantitative estimation of the magnetoelectric coupling coefficients was performed by tracking the changes in the phase and -amplitude of the piezoelectric signal signals when a in-plane dc magnetic field was applied parallel to the sample. Their non-resonant values typically range between 100-1200 mV/cm.Oe, thereby indicating a strong coupling between the magnetic and electrostrictive phases which can be used in different sensing and data storage applications. Keywords: Ferroics, Multiferroics, Liquid Phase Deposition, Scanning Probe Microscopy, Magnetic Properties, Electrical Properties

Yourdkhani, Amin

107

Viscosity B-coefficients and activation parameters for viscous flow of a solution of heptanedioic acid in aqueous sucrose solution  

Microsoft Academic Search

Viscosity and density data for the system of heptanedioic acid dissolved in aqueous sucrose solution at temperature range from 288.15 to 313.15 K have been measured. The viscosity B-coefficients for heptanedioic acid in aqueous sucrose solution has been calculated. The effect of temperature and sucrose concentration on the B-coefficients is discussed. On the basis of the Feakins equation, the activation

Tong-Chun Bai; Guo-Bing Yan

2003-01-01

108

Coupled Densification—Shape Distortion Analysis of Liquid Phase Sintering Affected By Gravity  

NASA Astrophysics Data System (ADS)

The paper presents a model of nonlinear viscous behavior in the examination of gravity-induced distortion during liquid phase sintering. The model uses a finite element formulation to describe densification, viscous flow, and the associated dimensional changes and component slumping during sintering. The approach assumes sintering is conducted under isothermal conditions with averaged material properties. The numerical results are compared with experimental data and with a mathematical model on the distortion during liquid phase sintering of tungsten heavy alloys. The preliminary conclusions aim to provide better understanding of dimensional control during liquid phase sintering.

Alvarado-Contreras, José A.; German, Randall M.; Maximenko, Andrey L.; Olevsky, Eugene A.

2014-02-01

109

Laser-induced separation of hydrogen isotopes in the liquid phase  

DOEpatents

Hydrogen isotope separation is achieved by either (a) dissolving a hydrogen-bearing feedstock compound in a liquid solvent, or (b) liquefying a hydrogen-bearing feedstock compound, the liquid phase thus resulting being kept at a temperature at which spectral features of the feedstock relating to a particular hydrogen isotope are resolved, i.e., a clear-cut isotope shift is delineated, irradiating the liquid phase with monochromatic radiation of a wavelength which at least preferentially excites those molecules of the feedstock containing a first hydrogen isotope, inducing photochemical reaction in the excited molecules, and separating the reaction product containing the first isotope from the liquid phase.

Freund, Samuel M. (Los Alamos, NM); Maier, II, William B. (Los Alamos, NM); Beattie, Willard H. (Los Alamos, NM); Holland, Redus F. (Los Alamos, NM)

1980-01-01

110

Catalytic esterification of sodium salicylate in third-liquid phase under ultrasound-assisted tri-liquid phase-transfer catalysis  

Microsoft Academic Search

The esterification of sodium salicylate to synthesize n-butyl salicylate was investigated via ultrasound-assisted tri-liquid phase-transfer catalysis. The third-liquid phase containing the catalytic intermediate tetra-n-butylphosphonium salicylate (ArCOOQ) was prepared from the reaction of sodium salicylate and tetra-n-butylphosphonium bromide with a large excess of NaBr in the aqueous phase. Under ultrasonic irradiation at 28kHz\\/300W, the product yield in the organic phase was

Hung-Ming Yang; Chien-Hsing Chen

2009-01-01

111

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

SciTech Connect

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.

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

112

Modeling, Design, Packaging and Experimental Analysis of Liquid-Phase Shear-Horizontal Surface Acoustic Wave.  

E-print Network

?? 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… (more)

Pollard, Thomas B.

2013-01-01

113

Carbide composition change during liquid phase sintering of a wear resistant alloy  

NASA Astrophysics Data System (ADS)

Constitutive liquid phase sintering is used to obtain fully dense parts of powdered STELLITE Alloy No. 6 PM (Co-29Cr-4.5W-l.2C- < 1B) with excellent wear resistance at elevated temperature. This alloy is characterized by a cobalt-rich fcc solid solution and interdendritic carbide phases in the as-atomized state. Compositional changes in the carbides prior to, and during, the liquid phase sintering were investigated via X-ray diffraction, optical microscopy, and Auger electron spectroscopy. The rejection of boron and cobalt by an M23C6-type carbide was identified as leading to the local formation of the liquid phase. A mechanism for the interactive role of the carbide composition change and the constitutive liquid phase sintering is proposed.

McGinn, P. J.; Kumar, P.; Miller, A. E.; Hickl, A. J.

1984-06-01

114

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

E-print Network

the effect of process variables during the transient liquid phase bonding of Inconel 625 and 718 superalloys in the final joint microstructures. Introduction Inconel 625 and 718 superalloys are extensively used in aero

Medraj, Mamoun

115

Transient liquid-phase infiltration of a powder-metal skeleton  

E-print Network

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 ...

Lorenz, Adam Michael, 1974-

2002-01-01

116

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

Microsoft Academic Search

Thermochemical energy conversion at moderate or low temperature (< about 400°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

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

1983-01-01

117

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

DOEpatents

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.

Raj, R.; Baik, S.

1985-11-12

118

Kinetics for synthesizing benzyl salicylate by third-liquid phase-transfer catalysis  

Microsoft Academic Search

The kinetics of esterification of sodium salicylate with benzyl bromide to produce benzyl salicylate was investigated via third-liquid phase-transfer catalysis. The formation of the third-liquid phase from the interaction of aqueous reactant, inorganic salts, organic solvent, and catalyst was investigated to find the characteristics of catalytic intermediate in the tri-liquid system. The minimum quantity of tetra-n-butylphosphonium bromide (TBPB) required to

Hung-Ming Yang; Ching Ching Li

2006-01-01

119

Equation of state for hydrocarbons in liquid phase  

SciTech Connect

To compile tables of thermodynamic properties of liquids, it is necessary to first describe the behavior of the thermodynamic surface in a selected range of parameters. A three-coefficient equation of state is proposed to describe the P-{rho}-T dependences of liquid hydrocarbons with various molecular structures (benzene, n-octane, isooctane, and 1-octene).

Naziev, D.Ya.; Gasanov, V.G. [Azerbaidzhanian Technical Univ., Baku (Russian Federation)

1995-07-20

120

Thermodynamic and kinetic studies of the liquid phase synthesis of tert-butyl ethyl ether using a reaction calorimeter  

SciTech Connect

The liquid-phase addition of ethanol to isobutene to give tert-butyl ethyl ether (ETBE) on the ion-exchange resin Lewatit K2631 has been studied in a calorimetric reactor. The heat capacity of ETBE and the enthalpy change of the ETBE synthesis reaction in the temperature range 312--333 K have been determined. ETBE heat capacity in the liquid phase has been found to follow the equation C{sub p} = 486.73 {minus} 2.253 (T/K) + 0.00479 (T/K){sup 2}. At 298 K the standard molar reaction enthalpy is {Delta}H{degree} = {minus}32.0 kJ/mol. A determination of the apparent activation energy of 86.5--89.2 kJ/mol has been performed graphically from the plots of heat flow rate versus time. An Eley-Rideal mechanism, with two active sites involved in the rate determining step, has been proved to be correct. From this model an apparent activation energy of 80.6 kJ/mol is deduced. A {minus}3.0 kJ/mol value has been found for the adsorption enthalpy of ethanol. This allows the estimation of the actual gel-phase activation energy of 77.6 kJ/mol.

Sola, L.; Pericas, M.A.; Cunill, F.; Tejero, J. [Univ. de Barcelona (Spain)

1995-11-01

121

Glycerol upgrading over zeolites by batch-reactor liquid-phase oligomerization: heterogeneous versus homogeneous reaction.  

PubMed

Glycerol upgrading to diglycerols in the presence of basic (Na+ or Cs+) ion-exchanged (FAU or BEA) zeolite catalysts was studied in a liquid-phase batch rector at 260 degrees C under normal pressure. Homogeneous NaHCO3 and CsHCO3 catalysts were studied for comparison. All the catalysts, including NaHCO3 and CsHCO3, displayed the same conversion-selectivity relationship. The selectivity to linear diglycerols decreased at higher conversions/reaction times owing to the consecutive formation of higher oligomers, with preferential further conversion of alpha,alpha'-diglycerol. The maximum yield of linear diglycerols was limited to about 30 %. The activities of the zeolites followed the order X>Y>Beta, independent of the alkali ion present. Catalysis by the zeolites starts with an induction period attributed to a slow leaching of alkaline cations from the zeolite. Thereafter, the reaction is characterized by a progressive loss of the microporous structure of the zeolite and increasing overlap of heterogeneous and homogeneous catalysis, where, primarily, the activity depends on the cation content of the zeolite. PMID:18821560

Krisnandi, Yuni K; Eckelt, Reinhard; Schneider, Matthias; Martin, Andreas; Richter, Manfred

2008-01-01

122

COMPUTATIONAL CHEMISTRY METHOD FOR PREDICTING VAPOR PRESSURES AND ACTIVITY COEFFICIENTS OF POLAR ORGANIC OXYGENATES IN PM2.5  

EPA Science Inventory

Parameterizations of interactions of polar multifunctional organic oxygenates in PM2.5 must be included in aerosol chemistry models for evaluating control strategies for reducing ambient concentrations of PM2.5 compounds. Vapor pressures and activity coefficients of these compo...

123

The effect of concentration- and temperature-dependent dielectric constant on the activity coefficient of NaCl electrolyte solutions  

NASA Astrophysics Data System (ADS)

Our implicit-solvent model for the estimation of the excess chemical potential (or, equivalently, the activity coefficient) of electrolytes is based on using a dielectric constant that depends on the thermodynamic state, namely, the temperature and concentration of the electrolyte, ?(c, T). As a consequence, the excess chemical potential is split into two terms corresponding to ion-ion (II) and ion-water (IW) interactions. The II term is obtained from computer simulation using the Primitive Model of electrolytes, while the IW term is estimated from the Born treatment. In our previous work [J. Vincze, M. Valiskó, and D. Boda, "The nonmonotonic concentration dependence of the mean activity coefficient of electrolytes is a result of a balance between solvation and ion-ion correlations," J. Chem. Phys. 133, 154507 (2010)], we showed that the nonmonotonic concentration dependence of the activity coefficient can be reproduced qualitatively with this II+IW model without using any adjustable parameter. The Pauling radii were used in the calculation of the II term, while experimental solvation free energies were used in the calculation of the IW term. In this work, we analyze the effect of the parameters (dielectric constant, ionic radii, solvation free energy) on the concentration and temperature dependence of the mean activity coefficient of NaCl. We conclude that the II+IW model can explain the experimental behavior using a concentration-dependent dielectric constant and that we do not need the artificial concept of "solvated ionic radius" assumed by earlier studies.

Valiskó, Mónika; Boda, Dezs?

2014-06-01

124

Engineering of a Stable Whole-Cell Biocatalyst Capable of (S)Styrene Oxide Formation for Continuous Two-Liquid-Phase Applications  

Microsoft Academic Search

Recombinant strains of Pseudomonas putida KT2440 carrying genetic expression cassettes with xylene oxygenase- and styrene monooxygenase-encoding genes on their chromosomes could be induced in shaking- flask experiments to specific activities that rivaled those of multicopy-plasmid-based Escherichia coli recom- binants. Such strains maintained the introduced styrene oxidation activity in continuous two-liquid-phase cultures for at least 100 generations, although at a lower

SVEN PANKE; VICTOR DE LORENZO; BERNARD WITHOLT; MARCEL G. WUBBOLTS

1999-01-01

125

Supramolecular solvent-based hollow fiber liquid phase microextraction of benzodiazepines.  

PubMed

A new, efficient, and environmental friendly hollow fiber liquid phase microextraction (HF-LPME) method based on supramolecular solvents was developed for extraction of five benzodiazepine drugs. The supramolecular solvent was produced from coacervation of decanoic acid aqueous vesicles in the presence of tetrabutylammonium (Bu4N(+)). In this work, benzodiazepines were extracted from aqueous samples into a supramolecular solvent impregnated in the wall pores and also filled inside the porous polypropylene hollow fiber membrane. The driving forces for the extraction were hydrophobic, hydrogen bonding, and ?-cation interactions between the analytes and the vesicular aggregates. High-performance liquid chromatography with photodiode array detection (HPLC-DAD) was applied for separation and determination of the drugs. Several parameters affecting the extraction efficiency including pH, hollow fiber length, ionic strength, stirring rate, and extraction time were investigated and optimized. Under the optimal conditions, the preconcentration factors were obtained in the range of 112-198. Linearity of the method was determined to be in the range of 1.0-200.0 ?g L(-1) for diazepam and 2.0-200.0 ?g L(-1) for other analytes with coefficient of determination (R(2)) ranging from 0.9954 to 0.9993. The limits of detection for the target benzodiazepines were in the range of 0.5-0.7 ?g L(-1). The method was successfully applied for extraction and determination of the drugs in water, fruit juice, plasma and urine samples and relative recoveries of the compounds studied were in the range of 90.0-98.8%. PMID:24267074

Rezaei, Fatemeh; Yamini, Yadollah; Moradi, Morteza; Daraei, Bahram

2013-12-01

126

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

E-print Network

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.

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

2012-02-20

127

Acoustic plate mode devices as liquid phase sensors  

SciTech Connect

Acoustic plate mode (APM) devices are sensitive to mass accumulated on and removed from a solid surface immersed in a liquid, as well as solution viscosity, density, electrical conductivity, and dielectric coefficient. Operating in direct contact with liquid solution at 158 MHz, APM devices have been used to monitor electrodeposition, electroless deposition, and metal film corrosion. Calibration of a 0.19 mm thick ST-quartz APM sensor by vacuum deposition of a silver film yielded a sensitivity of less than 1 ng/cm/sup 2/. Comparison of the frequency shift during Ag deposition to that obtained upon aqueous dissolution of the same Ag film demonstrates that the sensitivity to mass loading is not measurably altered by liquid contacting the device surface. Monitoring the propagation loss of the acoustic wave, which is proportional to viscosity over the 0.3 to 80 cP range, allows use of an APM device as a solid-state viscosity sensor. Acoustoelectric coupling between the APM and solution results in a velocity perturbation which depends on ionic conductivity and solution dielectric coefficient. 16 refs., 5 figs.

Ricco, A.J.; Martin, S.J.; Frye, G.C.; Niemczyk, T.M.

1988-01-01

128

Liquid phase fluid dynamic (methanol) run in the LaPorte alternative fuels development unit  

SciTech Connect

A fluid dynamic study was successfully completed in a bubble column at DOE's Alternative Fuels Development Unit (AFDU) in LaPorte, Texas. Significant fluid dynamic information was gathered at pilot scale during three weeks of Liquid Phase Methanol (LPMEOJP) operations in June 1995. In addition to the usual nuclear density and temperature measurements, unique differential pressure data were collected using Sandia's high-speed data acquisition system to gain insight on flow regime characteristics and bubble size distribution. Statistical analysis of the fluctuations in the pressure data suggests that the column was being operated in the churn turbulent regime at most of the velocities considered. Dynamic gas disengagement experiments showed a different behavior than seen in low-pressure, cold-flow work. Operation with a superficial gas velocity of 1.2 ft/sec was achieved during this run, with stable fluid dynamics and catalyst performance. Improvements included for catalyst activation in the design of the Clean Coal III LPMEOH{trademark} plant at Kingsport, Tennessee, were also confirmed. In addition, an alternate catalyst was demonstrated for LPMEOH{trademark}.

Bharat L. Bhatt

1997-05-01

129

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

PubMed Central

A large fraction of submicron atmospheric aerosol particles contains both organic material and inorganic salts. As the relative humidity cycles in the atmosphere and the water content of the particles correspondingly changes, these mixed particles can undergo a range of phase transitions, possibly including liquid–liquid phase separation. If liquid–liquid phase separation occurs, the gas-particle partitioning of atmospheric semivolatile organic compounds, the scattering and absorption of solar radiation, and the reactive uptake of gas species on atmospheric particles may be affected, with important implications for climate predictions. The actual occurrence of liquid–liquid phase separation within individual atmospheric particles has been considered uncertain, in large part because of the absence of observations for real-world samples. Here, using optical and fluorescence microscopy, we present images that show the coexistence of two noncrystalline phases for real-world samples collected on multiple days in Atlanta, GA as well as for laboratory-generated samples under simulated atmospheric conditions. These results reveal that atmospheric particles can undergo liquid–liquid phase separations. To explore the implications of these findings, we carried out simulations of the Atlanta urban environment and found that liquid–liquid phase separation can result in increased concentrations of gas-phase NO3 and N2O5 due to decreased particle uptake of N2O5. PMID:22847443

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

2012-01-01

130

Liquid phase esterification of acetic acid over WO3 promoted ?-SiC in a solvent free system.  

PubMed

A series of tungstate promoted ?-SiC catalysts was synthesized by a wetness impregnation method. The as synthesized catalysts were unambiguously characterized by XRD, Raman, FTIR, XPS, UV-Vis DRS, TEM, BET surface areas and FE-SEM, and simultaneously the total amount of the acidity of the catalysts was estimated by NH(3)-TPD. The catalytic activities of the synthesized materials were tested in the liquid phase esterification of acetic acid with n-butanol in a solvent free medium. The reaction parameters were optimized to a temperature of 120 °C, molar ratio of butanol and acetic acid of 1:2 and a reaction time of 6 h after performing a number of experiments. Under the optimum conditions, the catalytic esterification revealed a significant effect of 88% conversion with 100% selectivity to butyl acetate in 20 wt% WO(3)/?-SiC. This is the first report on the effective utilization of ?-SiC as a catalyst support for liquid phase esterification of acetic acid. PMID:23042240

Mishra, Gopa; Behera, Gobinda C; Singh, S K; Parida, K M

2012-12-21

131

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

PubMed Central

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

2013-01-01

132

Fluoroponytailed crown ethers and quaternary ammonium salts as solid-liquid phase transfer catalysts in organic synthesis.  

PubMed

Fluorous derivatives of dibenzo-18-crown-6 ether were prepared, and then successfully applied in representative solid-liquid phase transfer catalysis reactions, which were performed in standard organic solvents, such as chlorobenzene and toluene, as well as in fluorous solvents, such as perfluoro-1,3-dimethylcyclohexane. It was clearly shown that properly designed fluoroponytailed crown ethers could promote the disintegration of the crystal lattice of alkali salts, and transfer anions from the solid surface into an apolar, non-coordinating perfluorocarbon phase, for phase transfer catalysis reactions in organic synthesis. Furthermore, 3,5-bis(perfluorooctyl)benzyl bromide and triethylamine were reacted under mild conditions to provide an analogue of the versatile phase transfer catalyst, benzyltriethylammonium chloride, containing two fluoroponytails. This fluoroponytailed quaternary ammonium salt was also successfully employed as a catalyst in a variety of organic reactions conducted under solid-liquid phase transfer catalysis conditions, without a perfluorocarbon phase. Thus, being both hydrophobic and lipophobic, fluorous crown ethers and ammonium salts, could be rapidly recovered in quantitative yields, and reused without loss of activity, over several reaction cycles. PMID:21928010

Pozzi, Gianluca; Fish, Richard H

2012-01-01

133

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

PubMed

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

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

2013-10-01

134

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

NASA Astrophysics Data System (ADS)

A large fraction of submicron atmospheric particles contain 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 may be affected. Here, using optical and fluorescence microscopy, we present images that show the coexistence of two non-crystalline phases in particles generated from samples collected on multiple days in Atlanta, Georgia, and in particles generated in the laboratory using simulated atmospheric conditions. These results show that atmospheric particles can undergo liquid-liquid phase separations.

Bertram, A. K.; You, Y.; Renbaum-Wolff, L.; Carreras-Sospedra, M.; Hiranuma, N.; Smith, M.; Zhang, X.; Weber, R.; Shilling, J. E.; Dabdub, D.; Martin, S. T.

2012-12-01

135

Empty liquid phase of colloidal ellipsoids: The role of shape and interaction anisotropy  

NASA Astrophysics Data System (ADS)

We study the effect of anisotropic excluded volume and attractive interactions on the vapor-liquid phase transition of colloidal ellipsoids. In our model, the hard ellipsoid is embedded into an ellipsoidal well, where both the shape of the hard ellipsoid and that of the added enclosing ellipsoidal well can be varied independently. The bulk properties of these particles are examined by means of a van der Waals type perturbation theory and validated with replica exchange Monte Carlo simulations. It is shown that both the critical volume fraction (?c) and the critical temperature (Tc) of the vapor-liquid phase transition vanish with increasing shape anisotropy for oblate shapes, while ?c ? 0 and Tc ? 0 are obtained for very elongated prolate shapes. These results suggest that the chance to stabilize empty liquids (a liquid phase with vanishing density) is higher in suspensions of rod-like colloidal ellipsoids than in those of plate-like ones.

Varga, Szabolcs; Meneses-Júarez, Efrain; Odriozola, Gerardo

2014-04-01

136

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

SciTech Connect

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.

None

1998-12-21

137

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

Microsoft Academic Search

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

Tom B. Bechtel; Truman S. Storvick

1999-01-01

138

Liquid-Liquid Phase Equilibria in Binary Mixtures Under Negative Pressure  

Microsoft Academic Search

\\u000a Several binary or multicomponent solutions exhibit liquid-liquid phase transition; i.e. changing the temperature and\\/or pressure\\u000a and\\/or concentration etc., the initially homogeneous liquid can split into two or more liquid phases. In this paper we would\\u000a like to give examples where the extension of liquid-liquid solubility branches below p=0 gives us new information about the\\u000a studied binary and quasi-binary mixtures.

Attila R. Imre

139

Reentrant Liquid-Liquid Phase Separation in Protein Solutions at Elevated Hydrostatic Pressures  

NASA Astrophysics Data System (ADS)

We present results from small-angle x-ray scattering data on the effect of high pressure on the phase behavior of dense lysozyme solutions in the liquid-liquid phase separation region, and characterize the underlying intermolecular protein-protein interactions as a function of temperature and pressure in this region of phase space. A reentrant liquid-liquid phase separation region has been discovered at elevated pressures, which originates in the pressure dependence of the solvent-mediated protein-protein interactions.

Möller, Johannes; Grobelny, Sebastian; Schulze, Julian; Bieder, Steffen; Steffen, Andre; Erlkamp, Mirko; Paulus, Michael; Tolan, Metin; Winter, Roland

2014-01-01

140

Gas chromatographic measurements of activity coefficients at infinite dilution for refrigerants with a polyol ester oil as a stationary phase  

SciTech Connect

Activity coefficients at infinite dilution have been measured by gas chromatography for 14 refrigerants (R12, R22, R32, R124, R125, R134a, R142b, R143a, RE170, R236ea, R290, R600, R600a, and R236fa) as solutes, using a polyol ester oil (POE), EMKARATE by ICI, as a stationary phase (solvent). Instrumental analysis (NMR, IR) showed that the main components of the oil are pentaerithritol esters of carboxylic acids, and electrospray ionization spectrometry revealed an average molecular mass of the POE of 618 g/mol. The measurements were performed within a temperature range of 244 K to 313 K, but a specific temperature range for each refrigerant was adopted depending on its retention data. The experimental findings are well-represented by the equation: ln {gamma}{sub i}{sup {infinity}} = a{sub i} {minus} b{sub i}/T. Some refrigerants, i.e., R22, R124, R125, R236ea, and R236fa, show quite a considerable positive temperature dependence of their activity coefficients at infinite dilution, which can be attributed to hydrogen bonding with the POE, unlike other refrigerants that show a small, either positive or negative temperature dependence. To the authors` knowledge, there are no data in the literature on activity coefficients at infinite dilution for refrigerant and oil (lubricant) systems, and details on the solubility of refrigerants in oils are also extremely scarce.

Stryjek, R. [Polish Academy of Sciences, Warsaw (Poland). Inst. of Physical Chemistry] [Polish Academy of Sciences, Warsaw (Poland). Inst. of Physical Chemistry; Bobbo, S.; Camporese, R. [National Research Council, Padova (Italy). Inst. of Refrigeration] [National Research Council, Padova (Italy). Inst. of Refrigeration; Zilio, C. [Univ. di Padova (Italy). Dept. di Fisica Tecnica] [Univ. di Padova (Italy). Dept. di Fisica Tecnica

1999-05-01

141

Ethers from ethanol. 3: Equilibrium conversion and selectivity limitations in the liquid-phase synthesis of two tert-hexyl ethyl ethers  

SciTech Connect

Alternatives to the conventional isobutylene-derived ethers, namely methyl tert-butyl ether (MTBE) and ethyl tert-butyl ether (ETBE), are being explored, e.g., those produced from a combination of the branched C{sub 5} and C{sub 6} olefins with methanol or biomass-based ethanol. The conversion and selectivity of these ethers are thermodynamically limited. This paper, thus, describes the determination and analysis of the equilibrium limitations in the liquid-phase synthesis of two of the three possible isomers of tert-hexyl ethyl ether (THEE) from reactive C{sub 6} olefins and ethanol in the temperature range 298--353 K. The coupled reaction network for either of these two ethers involves two simultaneous esterification and one isomerization reactions, all being reversible. The equilibrium constants for these reactions, experimentally determined from equilibrium composition and the corresponding activity coefficients estimated by the UNIFAC method, decrease in the following order of tertiary olefins: 2M1P > isobutylene < 2,3DM1B {approx} 2M1B > 2M2P > 2M2B > 2,3DM2B for etherification reactions with ethanol, and (2,3DM1B {r_reversible} 2,3DM2B) > (2M1B {r_reversible} 2M2B) > (2M1P {r_reversible} 2M2P) for the isomerization reactions. This is explained on the basis of the relative stability of these olefins. The developed correlations are used to study the influence of process variables on the equilibrium conversion and selectivity of THEE formation.

Zhang, T.; Datta, R. [Univ. of Iowa, Iowa City, IA (United States). Dept. of Chemical and Biochemical Engineering

1995-07-01

142

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

SciTech Connect

The 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 LPMEOW Process Demonstration Unit was built at a site located at the Eastman complex in Kingsport. During this quarter, initial planning and procurement work began on the seven project sites which have been accepted for participation in the off-site, methanol product-use test plan. Two of the projects have begun pre-testing of equipment and three other projects have commenced with equipment procurement, Methanol produced from carbon monoxide (CO)- rich syngas at the Alternative Fuels Development Unit (AFDU) in LaPorte, TX has been shipped to four of the project sites in anticipation of the start of testing during the first quarter of calendar year 1998. Catalyst activity, as defined by the ratio of the rate constant at any point in time to the rate constant for a freshly reduced catalyst (as determined in the laboratory autoclave), continued to decline more rapidly than expected. In response to concentrations of arsenic and sulfbr detected on catalyst samples from the LPMEOW Reactor, Eastman replaced both the arsine- and sulfiwremoval material in the Eastman guard bed which treats the primary syngas feed stream (&danced Gas) prior to its introduction into both the Eastman fixed-bed methanol plant and the LPMEOWM Demonstration Unit. After restarting the demonstration unit, the catalyst deactivation rate remained essentially unchanged. Parallel testing in the laboratory using arsine-doped, and subsequently arsine- and SuIfi-doped syngas, ako ftiIed to prove that arsine was responsible for the higher-than-expected rate of catalyst deactivation in the demonstration unit. Based on the results of plant operation and catalyst sampling, DOE accepted a recommendation by Air Products and Eastman to drain the initial charge of catalyst from the reactor and replace the charge with fresh catalyst. Prior to this catalyst turnaround, a final test was performed to determine the impact of raising the operating temperature of the LPMEOW Reactor from 250"C to 260oC. carbon. Activation of the new flesh charge of catalyst began on 13 November 1997. Just as in the original start-up in April of 1997, only a partial charge of catalyst (20,700 pounds) was activated to limit the amount of material exposed to poisons at the outset. An attempted restart of the LPMEOW Demonstration Unit on 26 November 1997 was unsuccessfid; settling of the flesh catalyst appeared to have occurred in the LPMEOFP Reactor and gas inlet piping, which resulted in the plugging of the gas sparger at the bottom of the vessel.

None

1998-12-21

143

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

E-print Network

using ion-selective electrodes, were used to calculate the mean activity coefficients of NH4HCO3 Elsevier Science B.V. All rights reserved. Keywords: Activity coefficients; Ion-selective electrode containing a volatile component. Recently, with the development of ion-selective electrodes (ISE

Zhang, Luzheng

144

Hierarchical Nanoparticle Ensembles Synthesized by Liquid Phase Directed Self-Assembly  

E-print Network

-assembly guides the next. Liquid phase thin film dewetting has recently attracted much interest as a method assembly, Rayleigh-Plateau, volume-of-Fluid, hierarchical, nanoparticle assembly Chemical synthesis methods and optical7 applications stand to benefit from these size-dependent properties. However, approaches

Kondic, Lou

145

Molecular Tagging Diagnostics for the Study of Kinematics and Mixing in Liquid-Phase Flows  

E-print Network

of these efforts can be characterized under a broader common heading of Molecular Tagging Velocimetry (MTV.2.12 in the conference proceedings. #12;Past implementations of MTV in liquid phase flows primarily include the use is to give a brief summary of various MTV implemen- tations and their chemical mechanisms, followed by our

Koochesfahani, Manoochehr M.

146

Doktorarbeit Time-Resolved Photoelectron Spectroscopy in the Gaseous and Liquid Phase  

E-print Network

absorption spectroscopy in a liquid cell. The requirements for this thesis are a basic understanding in moPhD Thesis Doktorarbeit Time-Resolved Photoelectron Spectroscopy in the Gaseous and Liquid Phase (TRPES) which is sensitive to electronic and vibrational dynamics. In this tech- nique we use a short

Kersting, Roland

147

Coupled Ion Complexation and Exchange between Aqueous and Ionic Liquid Phases: A Thermodynamic Interpretation  

Microsoft Academic Search

Experimental studies of ion extraction from aqueous to ionic liquid phases have demonstrated that, in many cases, extraction of an ion from the aqueous phase is coupled to counterextraction of similarly charged ions from the ionic phase. These exchanges often involve coordination complexes that are not observed in extractions from aqueous phases to molecular organic liquids. We make a thermodynamic

Mark N. Kobrak

2008-01-01

148

Critical behaviour of ionic solutions in non-polar solvents with a liquid - liquid phase transition  

Microsoft Academic Search

Turbidity measurements showing crossover from mean-field to Ising criticality have been reported by Narayanan and Pitzer for the liquid - liquid phase transition in ionic solutions of alkyl-ammonium picrates in higher alcohols. The Ising region was found to increase with the dielectric permittivity D for solvents with 4 < D < 8. It was conjectured that the Ising region becomes

W. Schröer; M. Kleemeier; M. Plikat; V. Weiss; S. Wiegand

1996-01-01

149

Preparation, characterization and fundamental studies on graphenes by liquid-phase processing of graphite  

Microsoft Academic Search

Liquid-phase processing of graphite and graphite derivatives is one of the most promising methodologies for the mass production of graphene. Here, we present a brief overview of the main developments in this research area over the last few years, together with our own contributions to the field. Particularly, we discuss the preparation of graphenes both in aqueous and organic media

J. I. Paredes; S. Villar-Rodil; P. Solís-Fernández; M. J. Fernández-Merino; L. Guardia; A. Martínez-Alonso; J. M. D. Tascón

150

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

Microsoft Academic Search

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

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

2009-01-01

151

Fabrication of PbSnTe photovoltaic detectors using a Liquid Phase Epitaxy (LE) technique  

Microsoft Academic Search

All the steps in the fabrication of photovoltaic infrared detectors are described, from the growth of the single crystal until the complete characterization of the diodes. The formation of the PN junction by liquid phase epitaxy is described in detail. The detector characterization includes: the IxV curve, spectral response, response time, detection sensitivity, responsivity, and degradation due to the time

Sukarno Olavo Ferreira

1988-01-01

152

Environmental Application of Catalytic Processes: Heterogeneous Liquid Phase Oxidation of Phenol With Hydrogen Peroxide  

Microsoft Academic Search

The authors review the status of heterogeneous catalytic oxidation processes with hydrogen peroxide as an oxidant in a liquid phase. They focus on the priority organic pollutant–phenol as one of the most common persistent organic water contaminants, toxic even at low concentrations. A wide range of heterogeneous catalysts is covered, with a special emphasis on rapidly developing new catalytic systems.

Ekaterina V. Rokhina; Jurate Virkutyte

2010-01-01

153

Synthesis of Jasminaldehyde by Solid-Liquid Phase Transfer Catalysis Without Solvent, Under Microwave Irradiation  

Microsoft Academic Search

?-n-amylcinnamaldehyde (jasminaldehyde) was obtained with 82 % yield by solid-liquid phase transfer catalysis without solvent within 3 days at room temperature. By use of domestic microwave irradiation, the same yield was obtained within 1 minute at a power of 600 W.

David Abenhaïm; Chu Pham Ngoc Son; André Loupy; Nguyen Ba Hiep

1994-01-01

154

Optical and Electrical Diagnostics of the Effects of Conductivity on Liquid Phase Electrical Discharge  

Microsoft Academic Search

The influence of solution conductivity on liquid phase pulsed electrical discharge was investigated by optical emission spectroscopy in a reactor with point-to-plane electrode geometry. The emission intensities of hydroxyl (OH) radical, hydrogen (H) radical, and oxygen (O) radical were measured using an emission intensity calibration method which used argon gas as a chemical actinometer. Control experiments showed that the addition

Kai-Yuan Shih; Bruce R. Locke

2011-01-01

155

Effect of Pressure on Chemical Reaction in a Liquid Phase Electrical Discharge Reactor  

Microsoft Academic Search

The effects of pressure on liquid phase electrical discharge was investigated using a stainless steel high pressure reactor combined with a high voltage pulse forming network. The initiation breakdown voltage was obtained under various pressures up to 1379000 pascal (200 psi). The discharge characteristics including current and voltage waveforms as well as power per pulse were recorded. The effect of

Kai-Yuan Shih; Radu Burlica; Wright C. Finney; Bruce R. Locke

2007-01-01

156

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

NASA Technical Reports Server (NTRS)

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.

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

1984-01-01

157

The Contact Potential Between the Solid and Liquid Phases of Bismuth  

Microsoft Academic Search

Contact potential between the solid and liquid phases of bismuth.-In order to obtain as gas-free metal as possible, the bismuth was distilled into the highly exhausted apparatus. The contact potential was measured, by the standard Kelvin method, against a copper plate whose absolute potential was maintained constant by protecting it from the temperature changes incident to melting and solidifying the

Philip H. Dowling

1928-01-01

158

Transient liquid phase diffusion bonding of Udimet 720 for Stirling power converter applications  

Microsoft Academic Search

Udimet 720 has been selected for use on Stirling power converters for space applications. Because Udimet 720 is generally considered susceptible to strain age cracking if traditional fusion welding is used, other joining methods are being considered. A process for transient liquid phase diffusion bonding of Udimet 720 has been theoretically developed in an effort to eliminate the strain age

Donald L. Mittendorf; William G. Baggenstoss

1992-01-01

159

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

SciTech Connect

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.

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

160

Polydimethylsiloxane Microlens Arrays Fabricated Through Liquid-Phase Photopolymerization and Molding  

Microsoft Academic Search

We report on polydimethylsiloxane (PDMS) microlens arrays fabricated through liquid-phase photopolymerization and molding. The gist of this fabrication process is to form liquid menisci of variable radii of curvature at an array of apertures through pneumatic control, followed by photopolymerization under ultraviolet radiance. The resultant polymerized structures are then transferred to PDMS utilizing two molding steps. By adjusting the pneumatic

Xuefeng Zeng; Hongrui Jiang

2008-01-01

161

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

E-print Network

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.

Lei Wang; Jing Liu

2014-02-25

162

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

SciTech Connect

Liquid-entrained operations at the LaPorte Liquid Phase Methanol (LPMEOH) Process Development Unit (PDU) continued during June and July 1988 under Tasks 2.1 and 2.2 of Contract No. DE-AC22-87PC90005 for the US Department of Energy. The primary focus of this PDU operating program was to prepare for a confident move to the next scale of operation with an optimized and simplified process. Several new design options had been identified and thoroughly evaluated in a detailed process engineering study completed under the LPMEOH Part-2 contract (DE-AC22-85PC80007), which then became the basis for the current PDU modification/operating program. The focus of the Process Engineering Design was to optimize and simplifications focused on the slurry loop, which consists of the reactor, vapor/liquid separator, slurry heat exchanger, and slurry circulation pump. Two-Phase Gas Holdup tests began at LaPorte in June 1988 with nitrogen/oil and CO- rich gas/oil systems. The purpose of these tests was to study the hydrodynamics of the reactor, detect metal carbonyl catalyst poisons, and train operating personnel. Any effect of the new gas sparger and the internal heat exchanger would be revealed by comparing the hydrodynamic data with previous PDU hydrodynamic data. The Equipment Evaluation'' Run E-5 was conducted at the LaPorte LPMEOH PDU in July 1988. The objective of Run E-5 was to systematically evaluate each new piece of equipment (sparger, internal heat exchanger, V/L disengagement zone, demister, and cyclone) which had been added to the system, and attempt to run the reactor in an internal-only mode. In addition, a successful catalyst activation with a concentrated (45 wt % oxide) slurry was sought. 9 refs., 26 figs., 15 tabs.

Not Available

1991-01-02

163

Liquid phase epitaxial growth of GaAs  

SciTech Connect

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.

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

1997-10-01

164

Enrichment and sensitive determination of dichlorodiphenyltrichloroethane and its metabolites with temperature controlled ionic liquid dispersive liquid phase microextraction prior to high performance liquid phase chromatography.  

PubMed

Dichlorodiphenyltrichloroethane (DDT) and its main metabolites are important environmental pollutants and have been in the focusing center. It is of great value to develop simple, rapid, sensitive and easy to operate method for monitoring them. Present work established a novel temperature controlled ionic liquid dispersive liquid phase microextraction method in combination with high performance liquid chromatography for the enrichment and determination of DDT and its metabolites. Proposed method used only ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate ([C(6)MIM][PF(6)]) for the enrichment and overcame the demerits of conventional single drop liquid phase microextraction and dispersive liquid-liquid microextraction. Temperature has two functions here, one is to promote the dispersing of ionic liquid into the solution and forming infinitesimal micro-drop and increasing the chance of the analytes extracted into ionic liquid phase, and the other one is to perform phase-separation. A series of factors that would affect the extraction performance was systematically investigated and optimized. The experimental results indicated that the detection limits obtained for p,p'-DDD, p,p'-DDT, o,p'-DDT and p,p'-DDE were 0.24, 0.24, 0.45, 0.24 ng mL(-1), respectively. The linear ranges for them were from 1.0 to 100 ng mL(-1), and the precisions were between 3.8% and 6.7% (n=6). The proposed method was validated with four real-world samples and excellent results were achieved. PMID:19733736

Bai, Huahua; Zhou, Qingxiang; Xie, Guohong; Xiao, Junping

2009-09-28

165

Journal of Crystal Growth 241 (2002) 4550 Boron doping of silicon layers grown by liquid phase epitaxy  

E-print Network

Journal of Crystal Growth 241 (2002) 45�50 Boron doping of silicon layers grown by liquid phase film solar cell applications as it allows the growth of a back surface field and a lightly doped bulk in a single growth step. r 2002 Elsevier Science B.V. All rights reserved. Keywords: A3. Liquid phase epitaxy

166

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

ERIC Educational Resources Information Center

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…

Xu, Xinhua; Wang, Xiaogang; Wu, Meifen

2014-01-01

167

Solid-liquid phase diagrams for the determination of the solid state nature of both polymorphs of (RS)-2-(2-oxo-pyrrolidin-1-yl)-butyramide.  

PubMed

This work focuses on the determination of the solid state nature of (RS)-2-(2-oxo-pyrrolidin-1-yl)-butyramide (Etiracetam), the racemic intermediate of (S)-2-(2-oxo-pyrrolidin-1-yl)-butyramide, an Active Pharmaceutical Ingredient, marketed under the name Levetiracetam(®). It is show how this information can easily be extracted from solid-liquid phase diagrams of the racemic system. As two polymorphs of Etiracetam are known (Forms I and II), the analyses have been performed considering both polymorphs. The solid-liquid phase diagrams are determined experimentally, using Differential Scanning Calorimetry, and theoretically, using the Prigogine-Defay and Schroeder-Van Laar equations. Only the phase diagram involving the polymorph stable at higher temperatures (Form II) can be constructed experimentally. The theoretical phase diagram involving this polymorph compares well with the experimental one, thus allowing the use of theoretical equations for the prediction of the solid-liquid phase diagram involving Form I, which is meta-stable above 30.5 °C. Our findings confirm that both polymorphs are racemic compounds, which is also confirmed by XRPD analysis. PMID:22846407

Herman, Christelle; Haut, Benoît; Aerts, Luc; Leyssens, Tom

2012-11-01

168

Out-of-field activity in the estimation of mean lung attenuation coefficient in PET/MR  

NASA Astrophysics Data System (ADS)

In clinical PET/MR, photon attenuation is a source of potentially severe image artifacts. Correction approaches include those based on MR image segmentation, in which image voxels are classified and assigned predefined attenuation coefficients to obtain an attenuation map. In whole-body imaging, however, mean lung attenuation coefficients (LAC) can vary by a factor of 2, and the choice of inappropriate mean LAC can have significant impact on PET quantification. Previously, we proposed a method combining MR image segmentation, tissue classification and Maximum Likelihood reconstruction of Attenuation and Activity (MLAA) to estimate mean LAC values. In this work, we quantify the influence of out-of-field (OOF) accidental coincidences when acquiring data in a single bed position. We therefore carried out GATE simulations of realistic, whole-body activity and attenuation distributions derived from data of three patients. A bias of 15% was found and significantly reduced by removing OOF accidentals from our data, suggesting that OOF accidentals are the major contributor to the bias. We found approximately equal contributions from OOF scatter and OOF randoms, and present results after correction of the bias by rescaling of results. Results using temporal subsets suggest that 30-second acquisitions may be sufficient for estimation mean LAC with less than 5% uncertainty if mean bias can be corrected for.

Berker, Yannick; Salomon, André; Kiessling, Fabian; Schulz, Volkmar

2014-01-01

169

The stability of active balancing control using influence coefficients for a variable rotor system  

Microsoft Academic Search

High-speed rotating machines can be very sensitive to rotating mass unbalance that is a major source of harmful vibration for many types of rotating machinery. A balancing procedure is therefore needed for all high-speed rotating systems. To save the time and cost of off-line balancing, many researchers have developed on-line balancing devices and methods. In this paper, an active balancing

Jong-Soo Kim; Soo-Hun Lee

2003-01-01

170

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

SciTech Connect

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.

Bandaru, Jordana

2001-05-12

171

Stabilization of copper catalysts for liquid-phase reactions by atomic layer deposition.  

PubMed

Atomic layer deposition (ALD) of an alumina overcoat can stabilize a base metal catalyst (e.g., copper) for liquid-phase catalytic reactions (e.g., hydrogenation of biomass-derived furfural in alcoholic solvents or water), thereby eliminating the deactivation of conventional catalysts by sintering and leaching. This method of catalyst stabilization alleviates the need to employ precious metals (e.g., platinum) in liquid-phase catalytic processing. The alumina overcoat initially covers the catalyst surface completely. By using solid state NMR spectroscopy, X-ray diffraction, and electron microscopy, it was shown that high temperature treatment opens porosity in the overcoat by forming crystallites of ?-Al2 O3 . Infrared spectroscopic measurements and scanning tunneling microscopy studies of trimethylaluminum ALD on copper show that the remarkable stability imparted to the nanoparticles arises from selective armoring of under-coordinated copper atoms on the nanoparticle surface. PMID:24282166

O'Neill, Brandon J; Jackson, David H K; Crisci, Anthony J; Farberow, Carrie A; Shi, Fengyuan; Alba-Rubio, Ana C; Lu, Junling; Dietrich, Paul J; Gu, Xiangkui; Marshall, Christopher L; Stair, Peter C; Elam, Jeffrey W; Miller, Jeffrey T; Ribeiro, Fabio H; Voyles, Paul M; Greeley, Jeffrey; Mavrikakis, Manos; Scott, Susannah L; Kuech, Thomas F; Dumesic, James A

2013-12-16

172

A study on the pulsed laser printing of liquid-phase exfoliated graphene for organic electronics  

NASA Astrophysics Data System (ADS)

The aim of this work is the pulsed laser printing of liquid-phase exfoliated graphene in the nanosecond regime and the optimization of the printing process on Si/SiO2 and flexible polymer substrates (polyethylene naphthalate) via the laser-induced forward transfer technique (LIFT). The laser printing conditions and the optimum energy fluence window for reproducible deposition have been investigated, while the deposited graphene features have been studied morphologically and structurally by means of optical microscopy, micro-Raman spectroscopy and electrical characterization. LIFT experiments were carried out using the fourth harmonic (266 nm) of a pulsed ns Nd:YAG laser combined with a high-power imaging micromachining system to monitor the printing process throughout the experiments. The irradiation of our graphene solution resulted in the deposition of well-resolved patterns on different surfaces, highlighting LIFT as an alternative technique for the printing and patterning of liquid-phase exfoliated graphene for organic electronics applications.

Papazoglou, S.; Raptis, Y. S.; Chatzandroulis, S.; Zergioti, I.

2014-10-01

173

Selective growth of GaN by liquid phase electroepitaxy using aluminum oxide mask  

NASA Astrophysics Data System (ADS)

Aluminum oxide was investigated as a mask material for the selective growth of GaN by liquid phase electroepitaxy in comparison with SiO2, SiN, and W. SiO2 and W masks were dissolved in a solution and many polycrystals were generated on the SiN mask. Therefore, these masks are not suitable for selective growth. On the other hand, aluminum oxide was found durable in the solution, and growth selectivity was also achieved. Then, microchannel epitaxy was conducted using the aluminum mask by liquid phase electroepitaxy. Not only the selective growth but also the lateral growth of c-plane GaN with a width of about 8 µm was successfully achieved using the aluminum oxide mask.

Kambayashi, Daisuke; Takakura, Hiroyuki; Tomita, Masafumi; Iwakawa, Muneki; Mizuno, Yosuke; Yamada, Jumpei; Maruyama, Takahiro; Naritsuka, Shigeya

2014-11-01

174

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

E-print Network

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...

Wang, Lei

2014-01-01

175

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

NASA Astrophysics Data System (ADS)

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.

Dec, J. E.; Espey, C.

1993-10-01

176

THIN FILM SILICON FOR SOLAR CELL APPLICATION GROWN FROM LIQUID PHASE ON METALLURGICAL GRADE SILICON  

Microsoft Academic Search

Liquid phase epitaxy was applied to grow roughly 10 µm thick n-type polycrystalline silicon film on p-type metallurgical grade (MG) silicon substrate at 900° C in gallium\\/indium solution. GaAs, dissolved in the melt, served as an arsenic donor source for the as-grown film. The carrier concentration of both the substrate and the as- grown film was 1 × 1018 cm?3

H. G. Svavarsson; D. M. Danielsson; J. T. Gudmundsson

177

Advances in liquid-phase Friedel-Crafts acylation of aromatics catalyzed by heterogeneous solids  

Microsoft Academic Search

In the last few decades, significant improvements toward the development of environmentally benign processes have been achieved in the liquid-phase Friedel-Crafts acylation reactions. Many efforts have been devoted to the research on solid catalysts adequate to substitute homogeneous protonic acids or Lewis acids as traditionally employed catalysts in the acid-catalyzed Friedel-Crafts acylation processes. This short article describes the recent developments

Suman K. Jana

2006-01-01

178

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

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

179

Investigation of 2 liquid phase separation characteristics on the iodine–sulfur thermochemical hydrogen production process  

Microsoft Academic Search

Separation characteristics of 2 liquid phase, sulfuric acid phase and poly-hydriodic acid phase, in HI-H2SO4-I2 solution of the iodine–sulfur (IS) thermochemical hydrogen production process were measured in the wide operation temperature range, from 273 to 368 K in order to establish the closed-cycle operation technology and to improve thermal efficiency of the process. The effects of solution temperature and composition of

M Sakurai; H Nakajima; K Onuki; S Shimizu

2000-01-01

180

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

Microsoft Academic Search

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

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

1982-01-01

181

Recent developments and applications of liquid-phase strategies in organic synthesis  

Microsoft Academic Search

Chemistry on soluble polymer supports, termed liquid-phase organic synthesis, is developing into an increasingly viable alternative or adjunct to the classical solid-phase approach across the broad spectrum of polymer-supported organic chemistry. Recent advances in the field include the use of soluble polymers in the combinatorial synthesis of peptide and small-molecule libraries, as catalyst and reagent supports, and as functionalized polymer-quench

Paul Wentworth Jr

1999-01-01

182

Development of transient liquid phase sintered (TLPS) Sn–Bi solider pastes  

Microsoft Academic Search

Thermal analysis of pure Sn and Bi powder mixtures indicates that a transient liquid phase affect can be induced in the presence of paste chemicals. Initially liquid forms with a eutectic composition (i.e. 140°C), followed by rapid re-solidification and secondary melting at temperatures above 180°C. Upon reheating, processed solders do not remelt until temperatures above 220°C. Solder consolidation below the

X Qiao; S. F Corbin

2000-01-01

183

Liquid phase diffusion bonding and thermoelectric properties of Pb 1-xSnxTe compounds  

Microsoft Academic Search

The solidified Pb1-xSnxTe compounds with different x were joined by liquid phase diffusion bonding technique in order to prepare the segmented thermoelectric materials which had a fundamental FGM (functionally graded materials) structure. The Pb1-xSnxTe compound is a p-type semiconductor whose carrier concentration increases with increasing x. Therefore the maximum thermoelectric figure of merit of Pb1-xSnxTe shifted to a higher temperature

M. Hashimoto; I. Shiota; O. Ohashi; Y. Isoda; Y. Imai; Y. Shinohara; I. A. Nishida

1998-01-01

184

Development of transient liquid phase soldering process for LSI die-bonding  

Microsoft Academic Search

For high-power semiconductor devices with Cu lead-frames in plastic packages, die-bonding process that can obtain a heat-resistant bond (with high melting point) without large residual stress has been developed by applying transient liquid-phase bonding to the soldering process. A three-layered solder sheet the inner layer of which is 95Pb-5Sn solder and the surface layers of which are Pb-Sn eutectic solder

Goro IZUTA; Shunichi ABE; Jitsuho HIROTA; Osamu HAYASHI; Susumu HOSHINOUCHI

1993-01-01

185

Liquid phase sintered Cu–In composite solders for thermal interface material and interconnect applications  

Microsoft Academic Search

This study reports on the processing and characterization of composite solders produced by liquid phase sintering, which comprise\\u000a a high-melting phase such as Cu embedded in a matrix of a low-melting phase such as In. These solders combine higher electrical\\/thermal\\u000a conductivities with high mechanical compliance, and are suitable for a range of next-generation thermal interface material\\u000a and interconnect applications. After

J. Liu; P. Kumar; I. Dutta; R. Raj; R. Sidhu; M. Renavikar; R. Mahajan

186

Erbium doping in InGaAsP grown by liquid-phase epitaxy  

Microsoft Academic Search

The Er-doped InGaAsP epitaxial layers lattice-matched to InP with wavelengths of 1.29 and 1.55 ?m have been grown by liquid-phase epitaxy. When the Er amount doped in the InGaAsP growth solution is above 0.32 wt %, it will have a fairly rough surface morphology with many extensive deposits of erbium hydride and oxide. The lattice mismatch normal to the wafer

Meng-Chyi Wu; En-Hsing Chen; Tsung-Shune Chin; Yuan-Kuang Tu

1992-01-01

187

Detection of Enteroviruses and Rhinoviruses in Clinical Specimens by PCR and Liquid-Phase Hybridization  

Microsoft Academic Search

A sensitive method based on PCR followed by liquid-phase hybridization for detection of enterovirus and rhinovirus RNAs in clinical specimens and cell culture supernatants is described. RNA was extracted from stool samples, throat swabs, nasopharyngeal aspirates, cerebrospinal fluid, urine, and plasma with a com- mercial phenol-guanidinium-chloroform reagent and purified on a polysulfone membrane, on which the reversetranscriptasereactionwasalsodone.Twosetsofoligonucleotideprimersfromthe5*noncodingregion ofpicornaviruseswereselectedforDNAamplificationof153-bp(enterovirus)and120-bp(rhinovirus)regions. Double-stranded amplicons

PEKKA HALONEN; ELISABET ROCHA; JOHN HIERHOLZER; BRIAN HOLLOWAY; TIMO HYYPIA; PERTTI HURSKAINEN; ANDMARK PALLANSCH; Wallac Oy

1995-01-01

188

A microreactor functionalized with acoustic wave effects and a liquid phase catalytic reaction.  

PubMed

In a microreactor functionalized with the effects of acoustic waves such as surface acoustic waves (SAWs) and resonance oscillations (ROs) that can be generated on ferroelectric crystals by applying rf electric power, the acoustic wave-induced dynamic lattice displacement vertical to surface significantly enhanced the catalysis of Sc(OTf)(3) in aldol condensation reaction of benzaldehyde and acetophenone to chalcone, demonstrating that the functionalization provided the microreactor with reaction-controllable functions of promoting liquid phase catalytic reactions. PMID:20386801

Nishiyama, Hiroshi; Asari, Ryusuke; Inoue, Yasunobu

2010-06-21

189

Gas-liquid phase-transfer catalysis; A new continuous-flow method in organic synthesis  

Microsoft Academic Search

A synthetic method, gas-liquid phase-transfer catalysis (GL-PTC0), is described. GL-PTC is a continuous-flow procedure where gaseous reagents flow through a molten phase-transfer (PT) catalyst supported on a solid; no solvent is used. Reactions may develop through new mechanistic pathways compared with those of classical conditions; moreover, the reactions often occur in very selective ways. Some typical syntheses carried out under

Pietro Tundo; Giovanni Moraglio; Francesco Trotta

1989-01-01

190

Solid\\/liquid phase-transfer catalysis. Some models and solvent influence  

Microsoft Academic Search

The applicability of the models developed earlier for the topochemical reactions in the solid\\/liquid phase-transfer catalysis is discussed. Depending on the solvent and the catalyst the reaction may be inhibited by the crust of the solid inorganic product. Solvents like MeCN and THF, and catalysts such as polyethylene glycols loosen this crust, thus preventing the inhibition. The solvent influence using

Felix Sirovski; Christian Reichardt; Marina Gorokhova; Sergei Ruban; Elena Stoikova

1999-01-01

191

Determination of sintering parameters for liquid phase sintering of silicon nitride  

NASA Astrophysics Data System (ADS)

The sintering parameters of silicon nitride were determined during the second stage of liquid phase sintering via interrupted sinter forging tests under compressive uniaxial load. The silicon nitride with an yttria-alumina rich secondary phase (Saint-Gobain composition NB D300) was submitted to seven level of stress (from 0.24MPa to 9.41MPa) at three different temperatures (1500°C, 1550°C and 1600°C) with continuous monitoring of the axial and longitudinal shrinkage during all experiments to directly obtain the sintering stress, Poisson's ratio and bulk viscosity. The sintering stress measured in the first 1.5 minutes after reaching temperature was 7.5MPa at 1500°C (˜60% theoretical density), 21.5 MPa at 1550°C (˜70% dense) and 11.5MPa at 1600°C (˜80% dense). The bulk viscosity also peaks at the intermediate density at about 48GPas. This variation is largely attributed to the noticeable changes of microstructure during the second stage of liquid phase sintering, especially the overall pore size distribution as well as the degree to which the liquid phase is fully melted and partially or fully fills the smallest pores. The experimental data were then inserted into a numerical model developed by Abouaf. Proper fit of the model could not be obtained without considering the rearrangement stage of sintering. Considering both the rearrangement and solution-precipitation stages of densification, it was possible to determine the variation during sintering of different parameters that influences the liquid phase sintering and therefore the microstructure development.

Theron, Claire

192

Liquid phase transesterification of methyl salicylate and phenol over solid acids: Kinetic studies  

Microsoft Academic Search

The liquid phase transesterification of methyl salicylate and phenol to synthesize a value added ester, salol has been studied over the catalysts, ZrO2 (Z), SO42?\\/ZrO2 (SZ) and Mo(VI)\\/ZrO2 (MZ). Physical and chemical characterization of the catalysts in the form of sulfur and Mo(VI) contents, BET surface area, total surface acidity and powder XRD were conducted. Effects of various parameters, such

S. Z. Mohamed Shamshuddin; N. Nagaraju

2007-01-01

193

Growth and characterization of liquid phase epitaxial GaP layers  

E-print Network

Inside a High-vacuum Chamber . . . . . . . . . . . . . . . . . . . . . . . 3 3. Cross Section of Multi-well Sliding Graphite Boat. Solubility Curve of P in Ga Melt 5. Apparatus of LPE Growth by Tipping Method. 10 Dipping System Schematic for LPE..., this technique has become known as Liquid Phase Epitaxy. An LPE growing boat is shown in Fig. 3 for the epitaxial growth of three different layers. GALLIUM MELT GaP SOURCE MAGNESIUM GRAPHITE BOAT SUBSTRATE SLIDER PUSH ROD Fig. 3 . Cross section of multi...

Kao, Yung-Chung

2012-06-07

194

Gravity and configurational energy induced microstructural changes in liquid phase sintering  

NASA Technical Reports Server (NTRS)

Experiments were performed with W-Ni-Fe heavy alloys in order to measure the microstructural changes vs. position that occur in liquid-phase sintering under normal gravity. The experimentally observed segregation is less than the calculated equilibrium segregation due to the retarding effect from the rigid solid skeleton formed during sintering. These results improve understanding of microstructure, mechanical properties, component shape, and dimensional stability benefits that may be realized from low-gravity sintering.

Kipphut, C. M.; Bose, A.; Farooq, S.; German, R. M.

1988-01-01

195

Trends in liquid-phase microextraction, and its application to environmental and biological samples  

Microsoft Academic Search

Liquid phase microextraction (LPME) is a popular technique for sample pretreatment before the trace determination of target\\u000a compounds from complex matrices, examples being pesticides in environmental and food samples, or drug residuals in biological\\u000a samples such as blood or urine. LPME is simple, affordable, easy to operate, and highly sensitive. It is a miniaturized implementation\\u000a of conventional liquid-liquid extraction in

Dandan Han; Kyung Ho Row

196

Fabrication of textured ? (RE = Y, Gd) composites by infiltration and growth of ? preforms by liquid phases  

Microsoft Academic Search

A process for the fabrication of high-quality and near-net-shaped superconducting specimens of 0953-2048\\/11\\/5\\/014\\/img3 (Y-123) with uniformly distributed fine 0953-2048\\/11\\/5\\/014\\/img4 (Y-211) is discussed. The process involves the fabrication of 211 preforms by conventional ceramic routes such as uniaxial and isostatic pressing, injection moulding and slip casting, and pressureless infiltration basically from a reservoir containing liquid phases. A compact of 123 or

E. Sudhakar Reddy; T. Rajasekharan

1998-01-01

197

Transition liquid phase bonding of a Hastelloy X and the bond strength at 1173 K  

Microsoft Academic Search

Transition liquid phase (TLP) bonding has been conducted on a Hastelloy X using amorphous foil filler metals. The inserted fillers were made by rapid solidification of a Ni-15% Cr alloy containing 3 to 5 mass% boron as a melting point depressant. The microstructural change with isothermal bonding time from 2.4 to 38.4 ks was examined in the bond regions by

Tetsuro Toyoda; Taka O Endo

1996-01-01

198

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

PubMed Central

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

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

2014-01-01

199

Esterification of sodium 4-hydroxybenzoate by ultrasound-assisted solid-liquid phase-transfer catalysis using dual-site phase-transfer catalyst.  

PubMed

The catalytic esterification of sodium 4-hydroxybenzoate with benzyl bromide by ultrasound-assisted solid-liquid phase-transfer catalysis (U-SLPTC) was investigated using the novel dual-site phase-transfer catalyst 4,4'-bis(tributylammoniomethyl)-1,1'-biphenyl dichloride (BTBAMBC), which was synthesized from the reaction of 4,4'-bis(chloromethyl)-1,1'-biphenyl and tributylamine. Without catalyst and in the absence of water, the product yield at 60 °C was only 0.36% in 30 min of reaction even under ultrasound irradiation (28 kHz/300 W) and 250 rpm of stirring speed. When 1cm(3) of water and 0.5 mmol of BTBAMBC were added, the yield increased to 84.3%. The catalytic intermediate 4,4'-bis(tributylammoniomethyl)-1,1'-biphenyl di-4-hydroxybenzoate was also synthesized to verify the intrinsic reaction which was mainly conducted in the quasi-aqueous phase locating between solid and organic phases. Pseudo-first-order kinetic equation was used to correlate the overall reaction, and the apparent rate coefficient with ultrasound (28 kHz/300 W) was 0.1057 min(-1), with 88% higher than that (0.0563 min(-1)) without ultrasound. The esterification under ultrasonic irradiation using BTBAMBC by solid-liquid phase-transfer catalysis was developed. PMID:23972326

Yang, Hung-Ming; Chu, Wei-Ming

2014-01-01

200

Probing the stability of the spin-liquid phases in the Kitaev-Heisenberg model using tensor network algorithms  

NASA Astrophysics Data System (ADS)

We study the extent of the spin liquid phases in the Kitaev-Heisenberg model using infinite projected entangled-pair states tensor network ansatz wave functions directly in the thermodynamic limit. To assess the accuracy of the ansatz wave functions, we perform benchmarks against exact results for the Kitaev model and find very good agreement for various observables. In the case of the Kitaev-Heisenberg model, we confirm the existence of six different phases: Néel, stripy, ferromagnetic, zigzag, and two spin liquid phases. We find finite extents for both spin liquid phases and discontinuous phase transitions connecting them to symmetry-broken phases.

Osorio Iregui, Juan; Corboz, Philippe; Troyer, Matthias

2014-11-01

201

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

NASA Astrophysics Data System (ADS)

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 influence could be investigated solely. In this dissertation, the diffusional effects on the different stages of liquid phase sintering were analyzed. A shrinking core model is for the first time applied to the liquid phase sintered alloys to investigate the mechanism and kinetics of the solid solution formation during the rearrangement stage. Evidence of the formation of a solid solution layer is presented. The results of the shrinking core modeling are favorably compared with the observations on different samples with various sintering times. For the solution-reprecipitation stage, the diffusion of pores plays an important role on the densification behavior, bead formation, and final microstructure of the composites. The shape factor of grains has significant influence on the application of the Lifshitz Slyozov Encounter Modified (LSEM) model to the experimental results. The shape factor was incorporated in the LSEM model to better represent the actual grain morphology in liquid phase sintering. Dihedral angle is an important indicator of an equilibrium particle configuration. A new dihedral angle model based totally on the geometry of spherical solid grains without any further assumptions is developed to determine the dihedral angles measured in two-dimensional sections for extrapolation to three dimensions. The result shows that the average dihedral angle measured on sections is 14/15 the dihedral angle in three dimensions. The expected frequencies of the simulation are compared with the experimental results obtained from microgravity liquid phase sintered Fe-Cu alloys with four different solid volume fractions (50, 60, 70, 80vol% Fe balanced with Cu) and six different sintering times (10, 20, 30, 40, 60 and 330 minutes) when a 3-D dihedral angle with a standard deviation of 10°, in our case, 40° +/- 10°, was employed in the model. The fit of the model to the experimental data is in good agreement since all the computed values of chi2 are smaller than the critical value chi20.05,16. According to the experimental results, an equilibrium particle configuration was obtained very early on in microgravity processing.

Ye, Saiyin

202

Transient liquid phase bonding of titanium-, iron- and nickel-based alloys  

NASA Astrophysics Data System (ADS)

The operating temperature of land-based gas turbines and jet engines are ever-increasing to increase the efficiency, decrease the emissions and minimize the cost. Within the engines, complex-shaped parts experience extreme temperature, fatigue and corrosion conditions. Ti-based, Ni-based and Fe-based alloys are commonly used in gas turbines and jet engines depending on the temperatures of different sections. Although those alloys have superior mechanical, high temperature and corrosion properties, severe operating conditions cause fast degradation and failure of the components. Repair of these components could reduce lifecycle costs. Unfortunately, conventional fusion welding is not very attractive, because Ti reacts very easily with oxygen and nitrogen at high temperatures, Ni-based superalloys show heat affected zone (HAZ) cracking, and stainless steels show intergranular corrosion and knife-line attack. On the other hand, transient liquid phase (TLP) bonding method has been considered as preferred joining method for those types of alloys. During the initial phase of the current work commercially pure Ti, Fe and Ni were diffusion bonded using commercially available interlayer materials. Commercially pure Ti (Ti-grade 2) has been diffusion bonded using silver and copper interlayers and without any interlayer. With a silver (Ag) interlayer, different intermetallics (AgTi, AgTi2) appeared in the joint centerline microstructure. While with a Cu interlayer eutectic mixtures and Ti-Cu solid solutions appeared in the joint centerline. The maximum tensile strengths achieved were 160 MPa, 502 MPa, and 382 MPa when Ag, Cu and no interlayers were used, respectively. Commercially pure Fe (cp-Fe) was diffusion bonded using Cu (25 m) and Au-12Ge eutectic interlayer (100 microm). Cu diffused predominantly along austenite grain boundaries in all bonding conditions. Residual interlayers appeared at lower bonding temperature and time, however, voids were observed in the joint centerline at higher joining temperature and time. Dispersed Au-rich particles were observed in the base metal near interface. The highest ultimate tensile strengths obtained for the bonded Fe were 291+/-2 MPa using a Cu interlayer at 1030°C for 10 h and 315+/-4 MPa using a Au-12Ge interlayer at 950°C for 15 h. Commercially pure Ni (cp-Ni) was diffusion bonded using a Al, Au-12Ge or Cu interlayer. The formation of intermetallics could not be avoided when Al interlayer was used. Even though no intermetallics were obtained with Au-12Ge or Cu interlayer, appreciable strength of the joint was not found. Next, the simple bonding systems were modeled numerically. It is hoped that the simple models can be extended for higher order alloys. The modeling of TLP joint means to come up with a mathematical model which can predict the concentration profiles of diffusing species. The concentration dependence of diffusivity in a multi-component diffusion system makes it complicated to predict the concentration profiles of diffusing species. The so-called chemical diffusivity can be expressed as a function of thermodynamic and kinetic data. DICTRA software can calculate the concentration profiles using appropriate mobility and thermodynamic data. It can also optimize the diffusivity data using experimental diffusivity data. Then the optimized diffusivity data is stored as mobility data which is a linear function of temperature. In this work, diffusion bonding of commercially pure Ni using Cu interlayers is reported. The mobility parameters of Ni-Cu alloy binary systems were optimized using DICTRA/Thermocalc software from the available self-, tracer and chemical diffusion coefficients. The optimized mobility parameters were used to simulate concentration profiles of Ni-Cu diffusion joints using DICTRA/Thermocalc software. The calculated and experimental concentration profiles agreed well at 1100 °C. This method could not be extended for higher order alloys because of the lack of appropriate thermodynamic and kinetic database. In the third phase industrially important alloys such

Rahman, A. H. M. Esfakur

203

Determination of Activity Coefficients of di-(2-ethylhexyl) Phosphoric Acid Dimer in Select Organic Solvents Using Vapor Phase Osmometry  

SciTech Connect

Effective models for solvent extraction require accurate characterization of the nonideality effects for each component, including the extractants. In this study, the nonideal behavior of the industrial extractant di(2-ethylhexyl) phosphoric acid has been investigated using vapor pressure osmometry (VPO). From the osmometry data, activity coefficients for the HDEHP dimer were obtained based on a formulation of the regular solution theory of Scatchard and Hildebrand, and the Margules two- and three-suffix equations. The results show similarity with a slope-analysis based relation from previous literature, although important differences are highlighted. The work points towards VPO as a useful technique for this type of study, but care must be taken with the choice of standard and method of analysis.

Michael F. Gray; Peter Zalupski; Mikael Nilsson

2013-08-01

204

INTERNATIONAL CONFERENCE ON SEMICONDUCTOR INJECTION LASERS SELCO-87: Liquid phase epitaxial growth of GaInAsP/InP laser structures  

NASA Astrophysics Data System (ADS)

A modified single-phase liquid phase epitaxy method was developed on the basis of a novel variant of the growth boat. The method was used to grow GaInAsP/InP double heterostructures for lasers emitting at 1.3 and 1.55 ?m. The main properties of wide-contact diodes (radiation power and threshold current density) were adopted as the characteristics of the quality of heterostructures characterized by different configurations of active and guiding layers. The quality of the structure was confirmed by the fabrication of laser diodes of the following types: stripe with oxide insulation, clad-ridge waveguide, and double-channel planar buried.

Nohavica, D.; Têminová, J.; Berková, D.; Zagrádková, M.; Kortan, I.; Zelinka, I.; Walachová, I.; Malina, V.

1988-11-01

205

Kinetics for benzoylation of sodium 4-acetylphenoxide via third-liquid phase in the phase-transfer catalysis  

Microsoft Academic Search

In this research, the kinetics for synthesizing 4-acetylphenyl benzoate (R*COOR) from benzoylation of sodium 4-acetylphenoxide via third-liquid phase-transfer catalysis was investigated. The reaction rate was observed to be strongly dependent on agitation speeds in the third-phase catalytic reaction. By forming the third-liquid phase, the observed reaction can be greatly enhanced to give a product yield of 100% in a duration

Chin-Chen Huang; Hung-Ming Yang

2005-01-01

206

Coefficient scaling.  

PubMed

We prove a remarkably simple but powerful recursion relation for the coefficients of iterated polynomials. We also prove that the recursion relation holds for the coefficients of certain functions of the iterated polynomial. Using the recursion relations, we obtain a closed-form expression for the average number of closed-loop self-avoiding walks per site on a family of fractal lattices. We describe numerical results, which exhibit log-periodic oscillations, and find good agreement between these results and the theory developed here, which predicts the existence of the log-periodic oscillations and their amplitudes. Finally, we discuss insights gained into the mathematical origins of critical phenomena. PMID:11969435

Paul, G

1999-05-01

207

Commercial-Scale Demonstration of the Liquid Phase methanol (LPMEOH) Process A DOE Assessment  

SciTech Connect

The U.S. Department of Energy (DOE) Clean Coal Technology (CCT) Program seeks to offer the energy marketplace more efficient and environmentally benign coal utilization technology options by demonstrating them in industrial settings. This document is a DOE post-project assessment (PPA) of one of the projects selected in Round III of the CCT Program, the commercial-scale demonstration of the Liquid Phase Methanol (LPMEOH{trademark}) Process, initially described in a Report to Congress by DOE in 1992. Methanol is an important, large-volume chemical with many uses. The desire to demonstrate a new process for the production of methanol from coal, prompted Air Products and Chemicals, Inc. (Air Products) to submit a proposal to DOE. In October 1992, DOE awarded a cooperative agreement to Air Products to conduct this project. In March 1995, this cooperative agreement was transferred to Air Products Liquid Phase Conversion Company, L.P. (the Partnership), a partnership between Air Products and Eastman Chemical Company (Eastman). DOE provided 43 percent of the total project funding of $213.7 million. Operation of the LPMEOH Demonstration Unit, which is sited at Eastman's chemicals-from-coal complex in Kingsport, Tennessee, commenced in April 1997. Although operation of the CCT project was completed in December 2002, Eastman continues to operate the LPMEOH Demonstration Unit for the production of methanol. The independent evaluation contained herein is based primarily on information from Volume 2 of the project's Final Report (Air Products Liquid Phase Conversion Co., L.P. 2003), as well as other references cited.

National Energy Technology Laboratory

2003-10-27

208

Statistical thermodynamics of liquid-liquid phase separation in ternary systems during complex coacervation  

NASA Astrophysics Data System (ADS)

Liquid-liquid phase separation leading to complex coacervation in a ternary system (oppositely charged polyion and macroion in a solvent) is discussed within the framework of a statistical thermodynamics model. The polyion and the macroion in the ternary system interact to form soluble aggregates (complexes) in the solvent, which undergoes liquid-liquid phase separation. Four necessary conditions are shown to drive the phase separation: (i) (?23)3r/?23c?((64)/(9?2))(?23?3)2 , (ii) r?[(64(?23?3)2)/(9?2?233)]1/2 , (iii) ?23?((2?231-1))/(?23c?3) , and (iv) (?23)2/I?(8)/(3?)(2?231-1) (where ?23 is the surface charge on the complex formed due to binding of the polyelectrolyte and macroion, ?23c is the critical volume fraction of the complex, ?23 is the Flory interaction parameter between polyelectrolyte and macroion, ?231 is the same between solvent and the complex, ?3 is the volume fraction of the macroions, I is the ionic strength of the solution, ? is electrostatic interaction parameter and r is typically of the order of molecular weight of the polyions). It has been shown that coacervation always requires a hydrated medium. In the case of a colloidal macroion and polyelectrolyte coacervation, molecular weight of polyelectrolyte must satisfy the condition r?103Da to exhibit liquid-liquid phase separation. This model has been successfully applied to study the coacervation phenomenon observed in aqueous Laponite (macroion)-gelatin (polyion) system where it was found that the coacervate volume fraction, ??23˜?2312 (where ??23 is the volume fraction of coacervates formed during phase separation). The free energy and entropy of this process have been evaluated, and a free-energy landscape has been drawn for this system that maps the pathway leading to phase separation.

Pawar, Nisha; Bohidar, H. B.

2010-09-01

209

Microscopic Evidence for a dense liquid phase of calcium carbonate (Invited)  

NASA Astrophysics Data System (ADS)

In the classical sense, minerals are presumed to nucleate directly from solution by overcoming a size-dependent free energy barrier that scales as the ratio of the macroscopic mineral-water interfacial tension cubed to the square of the thermodynamic supersaturation. However, experimental observations of the early stages of calcium carbonate mineralization demonstrate that under certain conditions formation of the crystalline polymorphs is preceded by the apparently spontaneous appearance of nanoscopic clusters that aggregate to produce metastable amorphous phases. This aggregation-based pathway is seemingly at odds with classical expectations. This research (Wallace et al., in press, Science) uses computational approaches to characterize the thermodynamic and dynamic properties of hydrated calcium carbonate cluster species, which are thus far only loosely constrained by experimental investigations. Replica exchange molecular dynamics simulations are employed to probe the initial formation of the clusters and lattice gas simulations are used to explore the general behavior of clusters at the onset of mineralization. The results suggest the growth of carbonate clusters may indeed proceed in the absence of any significant thermodynamic barrier. Moreover, the dynamical properties of the clusters are consistent with those of a dense liquid phase. Coalescence and dehydration of the nanoscale droplets result in the formation of a phase whose structure is consistent with that of amorphous calcium carbonate. These findings indicate that a spontaneous liquid-liquid phase separation may occur within the range of supersaturations spanned by natural waters. The coexistence of the dense and dilute liquid phases is described by a liquid-liquid binodal that may express a lower critical point near ambient temperature. Though liquid-liquid separation in simulations of the CaCO3-H2O system is an unexpected result, it suggests a means of generating nano- and mesoscopic phases consistent with established phase separation mechanisms and experimental observations.

Wallace, A. F.; Hedges, L.; Fernandez-Martinez, A.; Raiteri, P.; Gale, J. D.; Waychunas, G.; Whitelam, S.; Banfield, J. F.; De Yoreo, J. J.

2013-12-01

210

Extended quantum U(1)-liquid phase in a three-dimensional quantum dimer model  

SciTech Connect

Recently, quantum dimer models have attracted a great deal of interest as a paradigm for the study of exotic quantum phases. Much of this excitement has centered on the claim that a certain class of quantum dimer model can support a quantum U(1)-liquid phase with deconfined fractional excitations in three dimensions. These fractional monomer excitations are quantum analogs of the magnetic monopoles found in spin ice. In this paper, we use extensive quantum Monte Carlo simulations to establish the ground-state phase diagram of the quantum dimer model on the three-dimensional diamond lattice as a function of the ratio {mu} of the potential to kinetic-energy terms in the Hamiltonian. We find that, for {mu}{sub c}=0.75{+-}0.02, the model undergoes a first-order quantum phase transition from an ordered ''R state'' into an extended quantum U(1)-liquid phase, which terminates in a quantum critical Rokhsar-Kivelson (RK) point for {mu}=1. This confirms the published field-theoretical scenario. We present detailed evidence for the existence of the U(1)-liquid phase and indirect evidence for the existence of its photon and monopole excitations. Simulations are benchmarked against a variety of exact and perturbative results, and a comparison is made of different variational wave functions. We also explore the ergodicity of the quantum dimer model on a diamond lattice within a given flux sector, identifying a new conserved quantity related to transition graphs of dimer configurations. These results complete and extend the previous analysis of O. Sikora et al.[Phys. Rev. Lett. 103, 247001 (2009)].

Sikora, Olga; Shannon, Nic; Pollmann, Frank; Penc, Karlo; Fulde, Peter [H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Max-Planck-Institut fuer Physik komplexer Systeme, D-01187 Dresden (Germany); Research Institute for Solid State Physics and Optics, H-1525 Budapest, P. O. Box 49 (Hungary); Max-Planck-Institut fuer Physik komplexer Systeme, D-01187 Dresden, Germany Asia Pacific Center for Theoretical Physics, Pohang (Korea, Republic of)

2011-09-15

211

Liquid Phase Deposition Of Thin Titanium Dioxide Films For NH3 Detection  

NASA Astrophysics Data System (ADS)

TiO2 thin films are prepared by a new method called Liquid Phase Deposition (LDP). The layers are obtained by the reaction between the metal fluorocomplex and boric acid in aqueous solution. The morphology of the films and the composition are investigated by scanning electron microscopy (SEM) and x-ray photoelectron spectrometry (XPS). The sorption properties of TiO2 film to NH3 are measured by the Quartz Crystal Microbalance (QCM) method. A correlation between NH3 concentration and the sorption ability of as-deposited and annealed samples is obtained.

Georgieva, V.; Stefchev, P.; Stefanov, P.; Spassov, L.; Raicheva, Z.; Ivanova, K.

2007-04-01

212

Electrical Characterization of Graphene Flakes Synthesized Using Liquid Phase Exfoliation of Graphite in Isopropyl Alcohol  

NASA Astrophysics Data System (ADS)

Liquid-phase exfoliation processes for synthesis of nano structures is often a simpler route to get functional nanomaterials in large scale. Here we will report on the synthesis of graphene flakes using exfoliation of bulk graphite in isopropyl alcohol. We will also present electrical characterization of thin film devices made from these exfoliated flakes. Temperature dependence of resistance performed for 10K T 300K shows a slow linear increase in resistance with decrease in temperature. Behavior of thin film devices made from these exfoliated flakes under electrochemical gating environment will be presented and discussed.

Talapatra, Saikat; Muchharla, Baleeswaraiah; Connolly, Mitchell; Winchester, Andrew; Ghosh, Sujoy; Kar, Swastik

2013-03-01

213

Organic salt-assisted liquid-phase exfoliation of graphite to produce high-quality graphene  

NASA Astrophysics Data System (ADS)

Certain ordinary organic salts, such as edetate disodium, sodium tartrate, potassium sodium tartrate and sodium citrate were found to have universal and efficient assistant effect for liquid-phase exfoliation of graphite in common organic solvents to produce pristine graphene. Up to 123 times enhanced exfoliation efficiency was observed when sodium citrate was introduced into an exfoliation system consisting of natural graphite powder and dimethyl sulfoxide. TEM, AFM, Raman spectroscopy, EDX, TGA, and FTIR analysis showed graphite was successfully exfoliated into single or few-layer graphene nanosheets which were free of defects and oxides. The method is simple, effective, safe and economical.

Du, Wencheng; Lu, Jie; Sun, Peipei; Zhu, Yinyan; Jiang, Xiaoqing

2013-05-01

214

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

NASA Astrophysics Data System (ADS)

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.

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

2011-11-01

215

Tritiated water processing using liquid phase catalytic exchange and solid oxide electrolyte cell  

SciTech Connect

Liquid phase catalytic exchange (LPCE) is an effective method for enrichment and removal of tritium from tritiated water. Combined electrolysis catalytic exchange (CECE) process is an attractive application of a LPCE column. We proposed a new process that improves the CECE process. Using a solid oxide electrolyte (SOE) cell for electrolysis makes the CECE process more energy efficient and eliminates other disadvantages such as large tritium inventory and extremely slow system response. When the cell is used for recombination, the system becomes even more simple, efficiently, reliable and safe. 21 refs., 9 figs.

Yamai, H.; Konishi, S.; Hara, M.; Okuno, K. [Japan Atomic Energy Research Inst., Ibaraki (Japan); Yamamoto, I. [Nagoya Univ. (Japan)

1995-10-01

216

Commercial-Scale Demonstration of the Liquid Phase Methanol (LOMEOH(TM)) Process  

SciTech Connect

The Liquid Phase Methanol (LPMEOEP") Demonstration Project at K.ingsport, 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 LPMEOHY Process Demonstration Unit is being built at a site located at the Eastman Chemical Company (Eastman) complex in Kingsport. On 4 October 1994, Air Products and Chemicals, Inc. (Air Products) and signed the agreements that would form the Partnership, secure the demonstration site, and provide the financial commitment and overall project management for the project. These partnership agreements became effective on 15 March 1995, when DOE authorized the commencement of Budget Period No. 2 (Mod. AO08 to the Cooperative Agreement). The Partnership has subcontracted with Air Products to provide the overall management of the project, and to act as the primary interface with DOE. As subcontractor to the Partnership, Air Products will also provide the engineering design, procurement, construction, and commissioning of the LPMEOHTM Process Demonstration Unit, and will provide the technical and engineering supervision needed to conduct the operational testing program required as part of the project. As subcontractor to Air Products, Eastman will be responsible for operation of the LPMEOHTM Process Demonstration Unit, and for the interconnection and supply of synthesis gas, utilities, product storage, and other needed sewices. The project involves the construction of an 80,000 gallons per day (260 tons-per-day (TPD)) methanol unit utilizing coal-derived synthesis gas fi-om 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 LPMEOHTM process is ideally suited for directly processing gases produced by modern day coal gasifiers. Originally tested at a small 3,200 gallons per day, 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.

None

1996-03-31

217

Laser-induced deposition of hetero-metallic structures from liquid phase  

NASA Astrophysics Data System (ADS)

Laser-induced chemical-liquid phase deposition of hetero-metallic (Gu-Cr) structures is demonstrated for the first time. The deposition of hetero-metallic structures is of special interest thanks to wider range of properties as compared to pure metals. The deposition was realized from the electrolyte solution based on copper sulphate and potassium dichromate. The focused beam of the continuous wave Ar+ laser generated in the multiwave regime was used for the structures precipitation. The chemical processes resulting in Cu-Cr structures deposition are analyzed emphasizing some features typical for laser-assisted methods.

Manshina, A.; Ivanova, T.; Povolotskiy, A.

2010-06-01

218

Transient liquid phase diffusion bonding of Udimet 720 for Stirling power converter applications  

NASA Astrophysics Data System (ADS)

Udimet 720 has been selected for use on Stirling power converters for space applications. Because Udimet 720 is generally considered susceptible to strain age cracking if traditional fusion welding is used, other joining methods are being considered. A process for transient liquid phase diffusion bonding of Udimet 720 has been theoretically developed in an effort to eliminate the strain age crack concern. This development has taken into account such variables as final grain size, joint homogenization, joint efficiency related to bonding aid material, bonding aid material application method, and thermal cycle.

Mittendorf, Donald L.; Baggenstoss, William G.

219

Hall Effect Studies of AlGaAs Grown by Liquid-Phase Epitaxy for Tandem Solar Cell Applications  

NASA Astrophysics Data System (ADS)

We report results from Hall effect studies on Al x Ga1- x As ( x = 0.23-0.24) with bandgap energies of 1.76 ± 0.01 eV grown by liquid-phase epitaxy (LPE). Room-temperature Hall measurements on unintentionally doped AlGaAs revealed p-type background doping for concentrations in the range 3.7-5.2 × 1016 cm-3. Sn, Te, Ge, and Zn-doped AlGaAs were also characterized to study the relationship between doping concentrations and the atomic fractions of the dopants in the melt. Temperature-dependent Hall measurements were performed to determine the activation energies of the four dopants. Deep donor levels (DX centers) were dominant for Sn-doped Al0.24Ga0.76As, but not for Te-doped Al0.24Ga0.76As. Comparison of the temperature-dependent Hall effect results for unintentionally and intentionally doped Al0.24Ga0.76As indicated that the impurity contributing to the p-type background doping had the same activation energy as Mg. We thus suggest a Te-doped emitter and an undoped or Ge-doped base to maximize the efficiency of Al x Ga1- x As ( x ˜ 0.23) solar cells grown by LPE.

Zhao, Xin; Montgomery, Kyle H.; Woodall, Jerry M.

2014-11-01

220

Production of the biopesticide azadirachtin by hairy root cultivation of Azadirachta indica in liquid-phase bioreactors.  

PubMed

Batch cultivation of Azadirachta indica hairy roots was carried out in different liquid-phase bioreactor configurations (stirred-tank, bubble column, bubble column with polypropylene basket, and polyurethane foam disc as root supports) to investigate possible scale-up of the A. indica hairy root culture for in vitro production of the biopesticide azadirachtin. The hairy roots failed to grow in the conventional bioreactor designs (stirred tank and bubble column). However, modified bubble column reactor (with polyurethane foam as root support) configuration facilitated high-density culture of A. indica hairy roots with a biomass production of 9.2 g l(-1)dry weight and azadirachtin yield of 3.2 mg g(-1) leading to a volumetric productivity of azadirachtin as 1.14 mg l(-1) day(-1). The antifeedant activity in the hairy roots was also evaluated by no choice feeding tests with known concentrations of the hairy root powder and its solvent extract separately on the desert locust Schistocerca gregaria. The hairy root powder and its solvent extract demonstrated a high level of antifeedant activity (with an antifeedant index of 97 % at a concentration of 2 % w/v and 83 % at a concentration of 0.05 % (w/v), respectively, in ethanol). PMID:23955295

Srivastava, Smita; Srivastava, Ashok K

2013-11-01

221

Liquid phase microextraction using knitting wool as the extractant phase holder before chromatographic analysis: a new approach for trace analysis.  

PubMed

In this paper, a novel liquid phase microextraction (LPME) approach was developed in which a piece of knitting wool was used as the extractant solvent holder. Owing to the absorbability of the wool, the extractant could be easily held within the material. When the wool containing the organic solvent was exposed to the sample solution, analytes could directly diffuse from the sample solution to the solvent. Ultraviolet (UV) filters ([2,4-dihydroxybenzophenone (BP-1), benzophenone (BP) and 2-hydroxy-4-methoxybenzophenone (BP-3)]) were used as model analytes to evaluate the procedure. Parameters that affect the extraction efficiency (selection of organic solvent, volume of the extractant, agitation speed, extraction time, salt concentration and pH) were investigated. The proposed method in combination with liquid chromatography-UV detection, provided good enrichment factors up to 366, with relative standard deviations of between 0.6% and 4.2% on the same piece of wool, and good linearity from 0.1 ng/ml to 100 ng/ml for all the analytes with regression coefficients of between 0.9998 and 0.9999. The limits of quantification of these compounds, calculated at S/N=10, were 0.1 ng/ml, 0.07 ng/ml and 0.1 ng/ml for BP-1, BP, BP-3, respectively. The method was applied to the determination of BP-type UV filters in swimming pool water. This is the first report of an application of knitting wool as a solvent holder for LPME. The procedure is cost-effective, and easy to operate. PMID:23276647

Zhang, Yufeng; Lee, Hian Kee

2013-01-18

222

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

USGS Publications Warehouse

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.

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

1995-01-01

223

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

PubMed Central

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

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

224

Thermodynamics of concentrated electrolyte mixtures. 9. Activity coefficients in aqueous NaBr-CaBr/sub 2/ mixtures at 25 /sup 0/C  

SciTech Connect

The activity coefficients of NaBr and CaBr/sub 2/ in NaBr-CaBr/sub 2/ aqueous mixtures have been measured at 25/sup 0/C over the ranges of ionic strengths 0.1 to 7.5 m. The measurements were made with a dual electrometer amplifier using Na and Ca ion selective electrodes against a Br ion selective electrode. The data were fitted to Harned's equation of the form log ..gamma../sub i/ = log ..gamma../sub i//sup 0/ - ..cap alpha../sub AB/y/sub B/ - ..beta../sub AB/y/sub B//sup 2/ to compute the trace activity coefficients and were also analyzed by using the Pitzer formation. Deviations from the Pitzer formalism were observed for the experimental activity coefficients in this mixture.

Usha, A.V.; Raju, K.; Atkinson, G.

1987-08-27

225

Membrane separation in green chemical processing: solvent nanofiltration in liquid phase organic synthesis reactions.  

PubMed

This paper describes ideas together with preliminary experimental results for applying solvent nanofiltration to liquid phase organic synthesis reactions. Membranes for organic solvent nanofiltration have only recently (during the 1990s) become available and, to date, have been applied primarily to food processing (vegetable oil processing, in particular) and refinery processes. Applications to organic synthesis, even at a laboratory feasibility level, are few. However, these membranes have great potential to improve the environmental performance of many liquid phase synthesis reactions by reducing the need for complex solvent handling operations. Examples that are shown to be feasible are solvent exchanges, where it is desired to swap a high molecular weight molecule from one solvent to another between separate stages in a complex synthesis, and recycle and reuse of homogeneous catalysts. In solvent exchanges, nanofiltration is shown to provide a fast and effective means of swapping from a high boiling point solvent to a solvent with a lower boiling point-this is a difficult operation by means of distillation. Solvent nanofiltration is shown to be able to separate two distinct types of homogeneous catalysts, phase transfer catalysts and organometallic catalysts, from their respective reaction products. In both cases the application of organic solvent nanofiltration allows several reuses of the same catalyst. Catalyst stability is shown to be an essential requirement for this technique to be effective. Finally, we present a discussion of scale-up aspects including membrane flux and process economics. PMID:12783814

Livingston, Andrew; Peeva, Ludmila; Han, Shejiao; Nair, Dinesh; Luthra, Satinder Singh; White, Lloyd S; Freitas Dos Santos, Luisa M

2003-03-01

226

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

SciTech Connect

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.

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

1983-05-01

227

Unusual stacking variations in liquid-phase exfoliated transition metal dichalcogenides.  

PubMed

Liquid-phase exfoliation of layered materials offers a large-scale approach toward the synthesis of 2D nanostructures. Structural properties of materials can however change during transition from bulk to the 2D state. Any such changes must be examined and understood for successful implementation of 2D nanostructures. In this work, we demonstrate nonbulk stacking sequences in the few-layer MoS2 and WS2 nanoflakes produced by liquid-phase exfoliation. Our analysis shows that nonbulk stacking sequences can be derived from its bulk counterparts by translational shifts of the layers. No structural changes within the layers were observed. Twenty-seven MoS2 and five WS2 nanoflakes were imaged and analyzed. Nine MoS2 and four WS2 nanoflakes displayed nonbulk stacking. Such dominance of the nonbulk stacking suggests high possibility of unusual stacking sequences in other 2D nanostructures. Notably, the electronic structure of some non bulk stacked bilayers presents characteristics which are uncommon to either the bulk phase or the single monolayer, for instance, a spin-split conduction band bottom. Our main characterization technique was annular dark-field scanning transmission electron microscopy, which offers direct and reliable imaging of atomic columns. The stacking characterization approach employed here can be readily applied toward other few-layer transition metal chalcogenides and oxides. PMID:24588696

Shmeliov, Aleksey; Shannon, Mervyn; Wang, Peng; Kim, Judy S; Okunishi, Eiji; Nellist, Peter D; Dolui, Kapildeb; Sanvito, Stefano; Nicolosi, Valeria

2014-04-22

228

Quantitative Thermal Analysis of Transient Liquid-Phase-Sintered Cu-Ni Powders  

NASA Astrophysics Data System (ADS)

Differential scanning calorimetry (DSC) was used to study the transient liquid phase sintering (TLPS) of elemental Ni and Cu powder mixtures. The initial melting behavior, kinetics of isothermal solidification, and remelt behavior of these powder mixtures were quantified, using DSC and metallographic techniques. The effects of the initial liquid distribution and processing temperature on these events were investigated. Quantitative DSC analysis indicates that suppressed liquid fractions form during TLPS at peak temperatures of 1090 °C and 1140 °C, due to solid-state interdiffusion prior to melting. Larger liquid fractions form at 1140 °C compared to 1090 °C, due to the recovery of some liquid previously lost to interdiffusion by dissolution at the higher peak temperature. This resulted in higher sintered densities at 1140 °C. Complete isothermal solidification of the Cu-rich transient liquid requires more time at 1140 °C due to higher liquid fractions initially formed at this temperature compared to those formed at 1090 °C. When the initial liquid is distributed nonuniformly, isothermal solidification times are also longer. The DSC and metallographic data indicate that the transient liquid phase (TLP) isothermally solidifies by limited long-range Cu diffusion into the Ni particles and by the epitaxial growth of a surrounding Cu-rich “layer” via the gradual outward progression of the solid/liquid interface at compositions given by the liquidus and solidus.

Turriff, D. M.; Corbin, S. F.

2008-01-01

229

Liquid phase preparation and fluorescence of flake-liked NdF{sub 3} nanomaterials  

SciTech Connect

Graphical abstract: Room-temperature emission spectra of NdF{sub 3} nanoflakes exhibit a strong luminescence emission peak at 402 nm when irradiated by an excitation wavelength of 250 nm. Display Omitted Highlights: ? NdF{sub 3} nanoflakes have been successfully prepared by a facile and repeatable liquid phase preparation. ? The action of oxalic acid in the reaction process was studied, showing important in the morphology of neodymium fluorides. ? The study on the fluorescent properties of flake-like NdF{sub 3} nanomaterials shows a strong emission peak at 402 nm by the excitation wavelength of 250 nm. -- Abstract: Neodymium fluoride nanoflakes were successfully prepared by a facile liquid phase preparation with Nd(NO{sub 3}){sub 3} and NaF as raw materials. In the process, oxalic acid acting as template agent was found to play important roles in the morphology of neodymium fluorides. The as-synthesized NdF{sub 3} nanoflakes were characterized by various techniques of X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray spectrometer instrument (EDS). The fluorescent properties of neodymium fluoride nanoflakes were investigated, showing a strong luminescence emission peak at 402 nm by the excitation wavelength of 250 nm.

Tian, Li, E-mail: ltian@hnust.edu.cn [Institute of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201 (China) [Institute of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201 (China); State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012 (China); Lian, Peili; Sun, Qiliang; Long, Peng; Xiang, Shaobin [Institute of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201 (China)] [Institute of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201 (China); Zhu, Guangshan [State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012 (China)] [State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012 (China)

2013-01-15

230

Densification during the supersolidus liquid-phase sintering of nickel-based prealloyed powder mixtures  

SciTech Connect

This article examines densification during supersolidus liquid-phase sintering (SLPS) of a mixture of two nickel-based prealloyed powders. The two powders were of similar compositions, where one powder alloyed with boron had a lower melting-temperature range than the other. Sintering of such binary powder systems is performed at temperatures above the solidus of the low-melting powder, to form a liquid phase that promotes densification. Measurements of shrinkage, sintered density, and melting were used to determine the densification mechanism. An increase in the fraction of the high-melting powder resulted in retardation of sintering. A densification model based on viscous flow as developed using rheological principles. The model is a first step in the extension of the conventional models of densification of single prealloyed powders to ones of mixtures of prealloyed powders. It incorporates the effects of homogenization between the two powders, specifically, the diffusion of boron from the low-melting to the high-melting powder. The densification of the powder mixture was found to depend on the extent of melting of the low-melting powder and the fraction of the high-melting powder.

Lal, A.; Iacocca, R.G.; German, R.M. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Engineering Science and Mechanics

1999-08-01

231

Mechanisms of bacterial inactivation in the liquid phase induced by a remote RF cold atmospheric pressure plasma jet  

NASA Astrophysics Data System (ADS)

A radio-frequency atmospheric pressure argon plasma jet is used for the inactivation of bacteria (Pseudomonas aeruginosa) in solutions. The source is characterized by measurements of power dissipation, gas temperature, absolute UV irradiance as well as mass spectrometry measurements of emitted ions. The plasma-induced liquid chemistry is studied by performing liquid ion chromatography and hydrogen peroxide concentration measurements on treated distilled water samples. Additionally, a quantitative estimation of an extensive liquid chemistry induced by the plasma is made by solution kinetics calculations. The role of the different active components of the plasma is evaluated based on either measurements, as mentioned above, or estimations based on published data of measurements of those components. For the experimental conditions being considered in this work, it is shown that the bactericidal effect can be solely ascribed to plasma-induced liquid chemistry, leading to the production of stable and transient chemical species. It is shown that HNO2, ONOO- and H2O2 are present in the liquid phase in similar quantities to concentrations which are reported in the literature to cause bacterial inactivation. The importance of plasma-induced chemistry at the gas-liquid interface is illustrated and discussed in detail.

van Gils, C. A. J.; Hofmann, S.; Boekema, B. K. H. L.; Brandenburg, R.; Bruggeman, P. J.

2013-05-01

232

Research on Si-Al based catalysts prepared by complete liquid-phase method for DME synthesis in a slurry reactor  

NASA Astrophysics Data System (ADS)

A series of Si-Al based DME synthesis catalysts were prepared by complete liquid-phase method and characterized by in situ XPS, XRD, N 2 adsorption and NH 3-TPD analyses. Based on the results, the addition of Si could adjust the pore structure and surface acidity of catalyst, exhibiting a strong promoting effect on the CO conversion and DME selectivity. However, when Si/Al ratio is higher, Si would cover active sites and increase the amount of strong acidity sites, causing the reduction in catalytic activity. It was found from in situ XPS characterization that Cu 0 is the active center of methanol synthesis in DME production, and the addition of Si changes the chemical surroundings of active components and weaken the interaction between Cu, Zn and Al, which maybe give rise to the decrease in catalyst stability.

Li, Zhihong; Zuo, Zhijun; Huang, Wei; Xie, Kechang

2011-01-01

233

Liquid-phase continuity and solute concentration dynamics during evaporation from porous media: pore-scale processes near vaporization surface.  

PubMed

Evaporation from porous media involves complex pore scale transport processes affecting liquid phase distribution and fluxes. Often, the initial evaporation rate is nearly constant and supplied by capillary flow from wetted zones below to the surface. Sustaining constant flow against gravity hinges on an upward capillary gradient and on liquid phase continuity with hydraulic conductivity sufficient for supplying evaporative flux. The pore scale liquid phase adjustments during evaporative displacement necessary for maintaining a constant flux have been postulated but rarely measured. In this study we employed detailed imaging using x-ray synchrotron radiation to study liquid phase distribution and dynamics at the most sensitive domain just below the surface of evaporating sand columns. Three-dimensional images at a resolution of 7 microns were obtained from sand column (mean particle size 0.6 mm) initially saturated with calcium iodide solution (4% by mass) to enhance image contrast. Detailed imaging of near-surface liquid phase distribution during evaporation confirmed phase continuity at micrometric scale and provided quantitative estimates of liquid conductance in agreement with values required to supply evaporative flux. Temporal variations in bulk salt concentrations determined from x-ray attenuation were proportional to evaporative water mass loss. Highly resolved salt concentration images revealed existence of evaporating chimneys that supply the bulk of evaporative demand. Delineated mass loss dynamics and salt distribution measured by the x-ray attenuation were in reasonable agreement with a simplified analytical convection-diffusion model for salt dynamics during evaporation from porous media. PMID:20481828

Shokri, N; Lehmann, P; Or, D

2010-04-01

234

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

NASA Astrophysics Data System (ADS)

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.

Amos, Fairland F.

235

COMMERCIAL-SCALE DEMONSTRATION OF THE LIQUID PHASE METHANOL (LPMEOH) PROCESS  

SciTech Connect

This project, which was sponsored by the U.S. Department of Energy (DOE) under the Clean Coal Technology Program to demonstrate the production of methanol from coal-derived synthesis gas (syngas), has completed the 69-month operating phase of the program. The purpose of this Final Report for the ''Commercial-Scale Demonstration of the Liquid Phase Methanol (LPMEOH{trademark}) Process'' is to provide the public with details on the performance and economics of the technology. The LPMEOH{trademark} Demonstration Project was a $213.7 million cooperative agreement between the DOE and Air Products Liquid Phase Conversion Company, L.P. (the Partnership). The DOE's cost share was $92,708,370 with the remaining funds coming from the Partnership. The LPMEOH{trademark} demonstration unit is located at the Eastman Chemical Company (Eastman) chemicals-from-coal complex in Kingsport, Tennessee. The technology was the product of a cooperative development effort by Air Products and Chemicals, Inc. (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 coal gasifiers. Originally tested at the Alternative Fuels Development Unit (AFDU), a small, DOE-owned process development facility 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. The LPMEOH{trademark} Demonstration Project accomplished the objectives set out in the Cooperative Agreement with DOE for this Clean Coal Technology project. Overall plant availability (defined as the percentage of time that the LPMEOH{trademark} demonstration unit was able to operate, with the exclusion of scheduled outages) was 97.5%, and the longest operating run without interruption of any kind was 94 days. Over 103.9 million gallons of methanol was produced; Eastman accepted all of the available methanol for use in the production of methyl acetate, and ultimately cellulose acetate and acetic acid.

E.C. Heydorn; B.W. Diamond; R.D. Lilly

2003-06-01

236

Modeling and processing of liquid-phase-sintered ?-TiAl during high-density infrared processing  

SciTech Connect

A new method for the rapid processing of thin gage sheet of traditionally difficult-to-process materials, such as y-TiAl, has been modeled and experimentally developed. The method uses high density infrared (HDI) rapid heating of a plasma arc lamp to liquid-phase sinter powder metal compact precursors to structures of varying densities. Material properties for precursor y-TiAl compacts were effectively chosen or determined and then used with a finite-volume heat-transfer modeling code to model the process. With the aid of the model, processing parameters were determined that allowed for a temperature gradient across the sheet that would produce a liquid-phase cast structure on the surface, residual powder on the backside, and a middle layer solid + liquid zone. Temperature and phase fields were predicted through the thickness of the sheet using the model. Fine grain, lamellar structured materials were produced in the liquid-phase-sintered zone.

Sabau, Adrian S [ORNL; Blue, Craig A [ORNL

2006-01-01

237

Anomalous Vortex Motion in the Quantum-Liquid Phase of Amorphous MoxSi1-x Films  

NASA Astrophysics Data System (ADS)

We measure, in real time (t), the fluctuating component of the flux-flow voltage V(t), ?V(t)?V(t)-V0, about the average V0 in the vortex-liquid phase of amorphous MoxSi1-x films. For the thick film, ?V(t) originating from the vortex motion is clearly visible in the quantum-liquid phase, where the distribution of ?V(t) is asymmetric, indicative of large velocity and/or number fluctuations of driven vortices. For the thin film the similar anomalous vortex motion is observed in nearly the same (reduced-)temperature regime. These results suggest that vortex dynamics in the low-temperature liquid phase of thick and thin films is dominated by common physical mechanisms, presumably related to quantum effects.

Okuma, S.; Kobayashi, M.; Kamada, M.

2005-02-01

238

Controlling interpenetration in metal-organic frameworks by liquid-phase epitaxy  

NASA Astrophysics Data System (ADS)

Metal-organic frameworks (MOFs) are highly porous materials generally consisting of two building elements: inorganic coupling units and organic linkers. These frameworks offer an enormous porosity, which can be used to store large amounts of gases and, as demonstrated in more recent applications, makes these compounds suitable for drug release. The huge sizes of the pores inside MOFs, however, also give rise to a fundamental complication, namely the formation of sublattices occupying the same space. This interpenetration greatly reduces the pore size and thus the available space within the MOF structure. We demonstrate here that the formation of the second, interpenetrated framework can be suppressed by using liquid-phase epitaxy on an organic template. This success demonstrates the potential of the step-by-step method to synthesize new classes of MOFs not accessible by conventional solvothermal methods.

Shekhah, Osama; Wang, Hui; Paradinas, Markos; Ocal, Carmen; Schüpbach, Björn; Terfort, Andreas; Zacher, Denise; Fischer, Roland A.; Wöll, Christof

2009-06-01

239

In situ transmission electron microscopy of solid-liquid phase transition of silica encapsulated bismuth nanoparticles.  

PubMed

The solid-liquid phase transition of silica encapsulated bismuth nanoparticles was studied by in situ transmission electron microscopy (TEM). The nanoparticles were prepared by a two-step chemical synthesis process involving thermal decomposition of organometallic precursors for nucleating bismuth and a sol-gel process for growing silica. The microstructural and chemical analyses of the nanoparticles were performed using high-resolution TEM, Z-contrast imaging, focused ion beam milling, and X-ray energy dispersive spectroscopy. Solid-liquid-solid phase transitions of the nanoparticles were directly recorded by electron diffractions and TEM images. The silica encapsulation of the nanoparticles prevented agglomeration and allowed particles to preserve their original volume upon melting, which is desirable for applications of phase change nanoparticles with consistently repeatable thermal properties. PMID:21796304

Hu, Jianjun; Hong, Yan; Muratore, Chris; Su, Ming; Voevodin, Andrey A

2011-09-01

240

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

SciTech Connect

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.

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

2007-12-01

241

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

NASA Astrophysics Data System (ADS)

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.

Kurhekar, Anil Sudhakar; Apte, Prakash R.

2013-02-01

242

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

PubMed

We report a soft liquid-phase adsorption (SLPA) technique for the fabrication of organic semiconductor films on wettability-patterned substrates using toluene/water emulsions. Wettabilitypatterned 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

Watanabe, Satoshi; Akiyoshi, Yuri; Matsumoto, Mutsuyoshi

2014-10-30

243

Liquid phase temperature determination in dense water sprays using linear Raman scattering.  

PubMed

Linear Raman scattering has been applied for the determination of the temperature of the liquid phase in water sprays under normal and superheated conditions. The envelope of the Raman OH-stretching vibration band of water is deconvoluted into five Gaussian peaks which can be assigned to five different intermolecular interactions (hydrogen bonding). The intensity of each of the peaks is a function of the temperature and the phase of the water under investigation. The interference of the Raman signals originating from the water vapor is eliminated from the Raman signals originating from the liquid water. Consequently the temperature of the liquid water droplets surrounded by water vapor is accessible which is favorable for the investigation of non-equilibrium sprays where the droplet temperature is different to the vapor temperature. PMID:24718172

Hankel, Robert Fabian; Günther, Astrid; Wirth, Karl-Ernst; Leipertz, Alfred; Braeuer, Andreas

2014-04-01

244

Regulating surface wettability of PEO/PLLA composite electrospun nanofibrous membrane for liquid phase filtration  

NASA Astrophysics Data System (ADS)

The PEO/PLLA composite nanofibrous membranes were prepared by electrospinning technique for liquid phase filtration application. In this experiment, PLLA homopolymer and PLLA-PEG copolymer were added into PEO solution to increase hydrophobicity of nanofibrous membrane surface. PLLA content was fixed at 30% by weight of total solid. Morphology and fiber diameter were characterized from scanning electron microscope (SEM) images. Fiber diameters of PEO/PLLA homopolymer and PEO/PLLA-PEG copolymer are 582+/-78 nm and 657+/-167 nm, respectively. Surface wettability property of PEO/PLLA composite nanofibrous membranes were measured by apparent water contact angle. The apparent water contact angle value of PEO/PLLA is 120°+/-2°, while PEO/PEG-b-PLLA is 99°+/-7°. The surface wettability of PEO/PLLA composite nanofibrous membranes can be modified by varying type of polymer.

Poonsit, Lalada; Sunthornvarabhas, Jackapon; Akira, Ito; Lertworasirikul, Amornrat

2014-06-01

245

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

PubMed Central

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

Kurhekar, Anil Sudhakar; Apte, Prakash R

2014-01-01

246

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

SciTech Connect

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.

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

2000-05-15

247

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

SciTech Connect

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.

Jayaraman, Saivenkataraman

2010-03-01

248

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

PubMed

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

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

2014-03-01

249

Liquid-Phase Sensor Using Shear Horizontal Surface Acoustic Wave Devices  

NASA Astrophysics Data System (ADS)

A surface acoustic wave (SAW) is perturbed from physical and/or chemical changes of an adjacent medium. If a liquid-phase sensor is realized, a shear horizontal SAW (SH-SAW) must be used. The SH-SAW sensors been investigated since 1987. Measuring objects of the SH-SAW sensor are not only immunoreactions but also liquid properties. Feature of the SH-SAW sensor is simultaneous detection of mechanical and electrical properties of liquid. In this paper, first, theory of the SH-SAW sensor is described. Then experimental results using the SH-SAW sensor on 36YX-LiTaO3 are introduced. Also, the sensor sensitivities of the SH-SAW sensors which are fabricated on piezoelectric substrates are theoretically compared.

Kondoh, Jun

250

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

PubMed

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

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

251

Simulating liquid-liquid phase separation and lipid transport on the Anton special purpose machine  

NASA Astrophysics Data System (ADS)

We present simulation data for a bilayer composed of a ternary mixture of cholesterol, dioloeoyl phosphatidylcholine and dipalmitoyl phosphatidylcholine. The composition is chosen to be in the two-phase region and the temperature in the vicinity of the miscibility transition. Using the Anton special purpose computer to generate continuous trajectories longer the ten microseconds---which admits complete mixing of the lipids---we observe robust liquid-liquid phase coexistence. The time-and ensemble-averaged mean squared displacement (MSD) displays anomalous scaling on timescales less than 50 nsec and normal diffusion on longer timescales. The short-time anomalous scaling is explained by a mode-coupling argument[Flenner et al Phys Rev E 79:011907(2009)]. The per-lipid MSD's suggest that a few lipids remain associated with the liquid ordered domain for the duration of the simulation, suggesting a possible mechanism for anomalous transport on experimentally accessible timescales.

Lyman, Edward; Sandar, Logan; Sodt, Alexader; Pastor, Richard W.

2013-03-01

252

Crystallization and Phase Changes in Paracetamol from the Amorphous Solid to the Liquid Phase  

PubMed Central

For the case of paracetamol, we show how terahertz time-domain spectroscopy can be used to characterize the solid and liquid phase dynamics. Heating of supercooled amorphous paracetamol from 295 K in a covered sample under vacuum leads to its crystallization at 330 K. First, form III is formed followed by the transformation of form III to form II at 375 K, to form I at 405 K, and finally melting is observed around 455 K. We discuss the difference between the featureless spectra of the supercooled liquid and its liquid melt. Lastly, we studied the onset of crystallization from the supercooled liquid in detail and quantified its kinetics based on the Avrami–Erofeev model. We determined an effective rate constant of k = 0.056 min–1 with a corresponding onset of crystallization at T = 329.5 K for a heating rate of 0.4 K min–1. PMID:24579729

2014-01-01

253

An immersed boundary-thermal lattice Boltzmann method for solid-liquid phase change  

NASA Astrophysics Data System (ADS)

In this work, an immersed boundary-thermal lattice Boltzmann method (IB-TLBM) is proposed to simulate solid-liquid phase change problems. To treat the velocity and temperature boundary conditions on the solid-liquid interface, immersed boundary method (IBM) is adopted, in which the solid-liquid interface is represented as a sharp interface rather than a diffusive interface and is tracked explicitly by Lagrangian grid. The surface forces along the immersed boundary, including the “momentum force” for velocity boundary condition and the “energy force” for temperature boundary condition, are calculated by the direct-forcing scheme. The moving velocity of solid-liquid interface induced by phase change is calculated by the amount of latent heat absorbed or released in a time step directly, with no need to compute temperature gradients in solid and liquid phases separately. The temperature on the solid-liquid interface is specified as the melting temperature, which means phase change happens at a constant temperature. As the solid-liquid interface evolves with time, the identification of phase of Eulerian points and the rearrangement of Lagrangian points are also considered. With regard to the velocity and temperature fields, passive scalar thermal lattice Boltzmann method (TLBM) with multiple-relaxation-time (MRT) collision schemes is adopted. Numerical examples, including conduction-induced melting in a semi-infinite space and melting in a square cavity, are carried out to verify the present method and good results are obtained. As a further application, melting in a circular cylinder with considering the motion of solid phase is simulated successfully by the present method; numerical results show that the motion of solid phase accelerates the melting process obviously.

Huang, Rongzong; Wu, Huiying

2014-11-01

254

High temperature furnace for liquid phase epitaxy of silicon carbide in microgravity  

NASA Astrophysics Data System (ADS)

The high temperature furnace for Liquid Phase Epitaxy (LPE) was developed by Swedish Space Corporation. It was developed for a Silicon Carbide liquid phase epitaxy microgravity experiment performed by Linköping University, Sweden. The LPE is capable of processing materials up to 1900°C in ultra clean atmosphere or vacuum in accordance with requirements for semiconductor crystal growth. The LPE has the capability to heat and cool the samples rapidly due to a high power input and a cooling gas system, this makes it possible to utilise it for short duration microgravity flights. The samples can be processed in isothermal conditions or with a temperature gradient up to 5°C/mm. The two resistive heaters are controlled individually which makes it possible for the user to pre-program an optional temperature profile for the experiment. The LPE was launched on the European microgravity rocket MASER 7 at Esrange in May 1996. For the first time under microgravity conditions four SiC samples were processed successfully. SiC has in comparison with Si superior properties regarding power electronics [1]. However, the quality of the material needs to be improved considerably before commercial production. Growth from a solution may give rise to an impurity microsegregation and growth instabilities due to the gravitation-induced convection, presumably resulting in an alteration of the point defect assembly. Growth under microgravity is thus a key for a better understanding of the growth process and defect formation. The material grown in microgravity is improved compared with on-ground reference growth.

Lockowandt, Christian; Yakimova, Rositza; Syväjärvi and, Mikael; Janzén, Erik

1999-04-01

255

Solid-state contributions to densification during liquid-phase sintering  

NASA Astrophysics Data System (ADS)

Densification via liquid-phase sintering generally requires transport of substantial amounts of dissolved solid through the liquid. However, in composite systems, such as W-Cu, solid solubility in the liquid is almost negligible, and densification is hindered by the low amount of total mass transport. In this case, solid-state sintering of the skeletal solid structure in the presence of the liquid is a significant densification mechanism. In this article, the relative contributions to densification of both liquid and solid mass transport mechanisms are considered. A computer simulation is constructed to predict the densification behavior and concurrent microstructural development of liquidphase sintered composites for realistic heating cycles. Governing differential equations for densification are derived from idealized models of the microstructure, considering grain size, diffusion distance from vacancy source to sink, pore size, and pore morphology. Temperature-dependent terms, including the diffusivity, solubility, and surface energy, govern densification and microstructural parameters, such as the grain size, dihedral angle, and contiguity. Predictions for the sintered density, grain size, and contiguity are compared to experimental results for the W-Cu and W-Cu-Ni systems with approximately 20 vol pct liquid. For W-Cu, which has almost no intersolubility, solid-state sintering of W in the presence of liquid Cu is the dominant densification mechanism. Nickel additions increase solid solubility in the liquid and improve typical liquid-phase sintering contributions to densification. Alternatively, high sintered densities can be achieved in the absence of solubility with a sufficiently small particle size due to the solid-state contribution.

Johnson, John L.; German, Randall M.

1996-12-01

256

Production of few-layer graphene through liquid-phase pulsed laser exfoliation of highly ordered pyrolytic graphite  

NASA Astrophysics Data System (ADS)

Graphene suspension was obtained through liquid-phase pulsed laser exfoliation of highly ordered pyrolytic graphite (HOPG). The liquid-phase pulsed laser process leaded to the compression and expansion of HOPG surface, resulting in the exfoliation of graphene sheets. Graphene sheets of ˜1 nm in thickness and micrometers in size were obtained. Transparent conductive graphene films were fabricated by vacuum filtration, showing an electrical conductivity of ˜1000 S/m and an optical transparency of ˜75% at 550 nm. This study demonstrated the growth of few-layer graphene by pulsed laser exfoliation of HOPG in liquid and explored its applications in transparent conductive films.

Qian, Min; Zhou, Yun Shen; Gao, Yang; Feng, Tao; Sun, Zhuo; Jiang, Lan; Lu, Yong Feng

2012-09-01

257

Superplasticity and thickness of liquid phase in the vicinity of solidus temperature in a 7475 aluminum alloy  

SciTech Connect

The temperature dependence of superplasticity has been investigated in the range including the solidus temperature for a 7475 aluminum alloy. It is found that the superplastic elongation shows the maximum value in the vicinity of the solidus temperature at a comparatively low strain rate. Filaments are observed on the fracture surfaces of the broken specimens tested below the solidus temperature. Further, the thickness of a liquid phase during superplastic deformation is discussed from four aspects: flow stress, fracture surface, thermal analysis and composition analysis. The thickness of the liquid phase is estimated to be 10--60 nm for the superplastically-deformed specimen.

Takayama, Y.; Tozawa, T.; Kato, H. [Utsunomiya Univ., Tochiga (Japan). Dept. of Mechanical Systems Engineering] [Utsunomiya Univ., Tochiga (Japan). Dept. of Mechanical Systems Engineering

1999-03-10

258

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

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.

Mónika Valiskó; Dezs? Boda

2014-09-15

259

One-dimensional virus transport in homogeneous porous media with time-dependent distribution coefficient  

Microsoft Academic Search

A stochastic model for one-dimensional virus transport in homogeneous, saturated, semi-infinite porous media is developed. The model accounts for first-order inactivation of liquid-phase and adsorbed viruses with different inactivation rate constants, and time-dependent distribution coefficient. It is hypothesized that the virus adsorption process is described by a local equilibrium expression with a stochastic time-dependent distribution coefficient. A closed form analytical

Constantinos V. Chrysikopoulos; Youn Sim

1996-01-01

260

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

NASA Astrophysics Data System (ADS)

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.

Atieh, Anas Mahmoud

261

Liquid-phase oxidation of cyclohexene in the presence of inhibitors and metallocomplexes chemically fixed on silica  

SciTech Connect

In an investigation of the mechanism of the liquid-phase oxidation of cyclohexene in the presence of heterogeneous catalysts, heterogeneous inhibitors - amines, ionol (BHT), the stable nitroxyl radical - were used, which made it possible to exclude the mutual influence of the sites of catalysis and inhibition. The efficiency factor was calculated for all types of inhibitors.

Berentsveig, V.V.; Barinova, T.V.; Staroverov, S.M.

1989-02-01

262

Use of a CCD camera for the thermographic study of a transient liquid phase bonding process in steel  

Microsoft Academic Search

The bonding of steel pieces and the development of novel soldering methods, appropriate to the extended variety of applications of steels nowadays, bring the sensing of temperature an outstanding role in any metallurgical process. Transient liquid phase bonding (TLPB) processes have been successfully employed to join metals, among them steels. A thin layer of metal A, with a liquids temperature

Eduardo H. Castro; Carlos Epelbaum; Angel Carnero; Bibiana Arcondo

2001-01-01

263

Magnesium gallate spinel: a substrate for the direct liquid-phase epitaxial growth of (Ga,Al)As  

Microsoft Academic Search

The single-crystal growth of the cubic spinel, MgGa2O4, by the Czochralski technique is reported. Moreover, experiments are described in which this material is used as a substrate for the first direct (single-step) liquid-phase epitaxial growth of ?111? (Ga,Al)As.

B. A. Scott; K. H. Nichols; R. M. Potemski; J. M. Woodall

1972-01-01

264

Novelties of microwave irradiated solid–liquid phase transfer catalysis (MISL-PTC) in synthesis of 2?-benzyloxyacetophenone  

Microsoft Academic Search

2?-Benzyloxyacetophenone is an important pharmaceutical intermediate for the manufacture of drugs used as diuretics, antihypertensive, platelet, antiaggregant, lipoxygenase, analgesics and prostaglandin, and for treatment of metabolic disorders. Microwave irradiation has been widely used for the rapid synthesis of a variety of compounds. In the current work, for the first time, novelties of low power microwave irradiated solid–liquid phase transfer catalysis,

Ganapati D. Yadav; Priyal M. Bisht

2004-01-01

265

Novelties of kinetics of chemoselective reduction of citronellal to citronellol by sodium borohydride under liquid–liquid phase transfer catalysis  

Microsoft Academic Search

Borohydride reductions, although common, have not been studied from kinetic and mechanistic view points due to complex chemistry and more so, there is no report on kinetics and mechanism of such reductions under phase transfer catalysis. The novelties of phase transfer catalysed chemoselective reduction of citronellal to citronellol using sodium borohydride were studied in detail in liquid–liquid phase transfer catalysis

Ganapati D. Yadav; Sharad V. Lande

2006-01-01

266

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

Microsoft Academic Search

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

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

2007-01-01

267

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

PubMed

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

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

2014-07-23

268

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

269

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...

270

Activity coefficients of DL-valine in aqueous solutions of KCl at 25°C. Measurement with ion selective electrodes and modelling  

Microsoft Academic Search

Electrochemical cells with two ion selective electrodes, a cation and an anion ion selective electrode, versus a double junction reference electrode were used to measure the activity coefficients of DL-valine at 298.15 K, up to 0.5 molality, in aqueous solutions of KCl up to 1.0 molality. The results obtained in this work are compared with those reported before for the

Mohammad K. Khoshkbarchi; Juan H. Vera

1996-01-01

271

Liquid-phase benzene oxidation to phenol with molecular oxygen catalyzed by Cu-zeolites  

SciTech Connect

The oxidation of benzene to form phenol using cuprous chloride as a catalyst has been reported by Sasaki and his co-workers, who used reaction system oxygen molecules as the oxidant. Takehira and his co-workers have studied benzene oxidation with molecular oxygen catalyzed by Cu(II) salts in the presence of ascorbic acid. Cu ion-exchanged zeolites have been reported to be useful as catalysts for the gas-phase oxidation of some organic materials, and copper ions in zeolites have been indicated to have redox properties according to physicochemical measurements. Armed with this knowledge, the authors have tried the liquid-phase oxidation of benzene with molecular oxygen under atmospheric pressure at room temperature using Cu ion-exchanged zeolite catalysts in the presence of ascorbic acid as a reducing reagent for Cu ions. The catalytic behavior of the Cu zeolites for the benzene oxidation was compared with that of nonanchored cupric and cuprous chloride catalysts. Also, some Cu catalysts impregnated on some amorphous oxide supports, in addition to the zeolites, were tested as catalysts for benzene oxidation with molecular oxygen. 13 refs., 5 figs., 3 tabs.

Ohtani, Tsuyoshi; Nishiyama, Satoru; Tsuruya, Shigeru [Kobe Univ. (Japan)] [and others] [Kobe Univ. (Japan); and others

1995-08-01

272

Growth of MgxZn1-xO/ZnO Heterostructures by Liquid Phase Epitaxy  

NASA Astrophysics Data System (ADS)

We investigate the fabrication of thermodynamically stable (0001)MgxZn1-xO/ZnO wurtzite heterostructures by liquid phase epitaxy (LPE) for the solid-solution range of 0 ? x ? 0.2. A continuous reaction of MgCl2/ZnCl2 and K2CO3 is applied to form MgxZn1-xO. Mirror-like films of the thickness ? 4 ?m have been grown uniformly on hydrothermal (0001)ZnO substrates for the first time by LPE. The solubility limit of 6 mol % Mg on Zn sites in ZnO at 640°C is revealed. For the concentration range of 0 ? x ? 0.06 the lattice parameter c decreases from 5.207 to 5.203 Å, the X-ray rocking curve ?-scan full-width half-maximum (FWHM) increases from 15 to 176 arcsec, and the donor-bound low-temperature (3 K) photoluminescence (PL) peak signal from the band gap shifts from 3.36 to 3.43 eV, respectively. The critical film thickness for misfit-induced cracking is estimated for MgxZn1-xO films with x ? 0.3 grown on (0001) and (000\\bar{1})ZnO.

Sato, Hideto; Ehrentraut, Dirk; Fukuda, Tsuguo

2006-01-01

273

Interplay of the Glass Transition and the Liquid-Liquid Phase Transition in Water  

PubMed Central

Water has multiple glassy states, often called amorphous ices. Low-density (LDA) and high-density (HDA) amorphous ice are separated by a dramatic, first-order like phase transition. It has been argued that the LDA-HDA transformation connects to a first-order liquid-liquid phase transition (LLPT) above the glass transition temperature Tg. Direct experimental evidence of the LLPT is challenging to obtain, since the LLPT occurs at conditions where water rapidly crystallizes. In this work, we explore the implications of a LLPT on the pressure dependence of Tg(P) for LDA and HDA by performing computer simulations of two water models – one with a LLPT, and one without. In the absence of a LLPT, Tg(P) for all glasses nearly coincide. When there is a LLPT, different glasses exhibit dramatically different Tg(P) which are directly linked with the LLPT. Available experimental data for Tg(P) are only consistent with the scenario including a LLPT. PMID:22550566

Giovambattista, Nicolas; Loerting, Thomas; Lukanov, Boris R.; Starr, Francis W.

2012-01-01

274

Liquid phase exfoliation of 2D layered materials and their application  

NASA Astrophysics Data System (ADS)

In this work, several materials possessing a layered structure were investigated using a technique of exfoliation in liquid phase to produce few- to mono-layers of the material. Materials exfoliated in such a way included graphite, boron nitride, molybdenum disulfide and tungsten disulfide. Subsequent transmission electron microscopy and accompanying electron diffraction patterns revealed that few and mono layer forms of these materials have been realized through this exfoliation method. Ultraviolet-visible spectroscopy confirmed the shifting of the band gaps in molybdenum and tungsten disulfides that is predicted in reducing the number of layers of these materials and was also used to confirm the band gap of the boron nitride. As a potential application, exfoliated molybdenum disulfide was used in the construction of electrodes for electrical charge storage in an electrochemical double layer capacitor, or supercapacitor, style device. Cyclic voltammetry, galvanostatic charge discharge, and electrochemical impedance spectroscopy measurements were performed using three different electrolytes, which showed good capacitive behavior for these devices. Using the data from electrochemical impedance spectroscopy, equivalent circuit models were generated to represent the systems in different electrolytes. From this, it was determined that the capacitive behavior of these systems was partially diffusion limited.

Winchester, Andrew J.

275

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

PubMed

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. PMID:25399190

Lu, Qing; Kim, Jaegil; Farrell, James D; Wales, David J; Straub, John E

2014-11-14

276

Microstructural evolution during transient liquid phase bonding of Inconel 738LC using AMS 4777 filler alloy  

SciTech Connect

IN-738LC nickel-based superalloy was joined by transient liquid phase diffusion bonding using AMS 4777 filler alloy. The bonding process was carried out at 1050 Degree-Sign C under vacuum atmosphere for various hold times. Microstructures of the joints were studied by optical and scanning electron microscopy. Continuous centerline eutectic phases, characterized as nickel-rich boride, chromium-rich boride and nickel-rich silicide were observed at the bonds with incomplete isothermal solidification. In addition to the centerline eutectic products, precipitation of boron-rich particles was observed in the diffusion affected zone. The results showed that, as the bonding time was increased to 75 min, the width of the eutectic zone was completely removed and the joint was isothermally solidified. Homogenization of isothermally solidified joints at 1120 Degree-Sign C for 300 min resulted in the elimination of intermetallic phases formed at the diffusion affected zone and the formation of significant {gamma} Prime precipitates in the joint region. - Highlights: Black-Right-Pointing-Pointer TLP bonding of IN-738LC superalloy was performed using AMS 4777 filler alloy. Black-Right-Pointing-Pointer Insufficient diffusion time resulted in the formation of eutectic product. Black-Right-Pointing-Pointer Precipitation of B-rich particles was observed within the DAZ. Black-Right-Pointing-Pointer The extent of isothermal solidification increased with increasing holding time. Black-Right-Pointing-Pointer Homogenizing of joints resulted in the dissolution of DAZ intermetallics.

Jalilvand, V., E-mail: jalilvand@aut.ac.ir [Department of Mining and Metallurgical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran 15875-4413 (Iran, Islamic Republic of); Omidvar, H. [Department of Mining and Metallurgical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran 15875-4413 (Iran, Islamic Republic of)] [Department of Mining and Metallurgical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran 15875-4413 (Iran, Islamic Republic of); Shakeri, H.R. [Department of Materials Science and Engineering, University of Toronto, Toronto, Ontario M5S 3E4 (Canada)] [Department of Materials Science and Engineering, University of Toronto, Toronto, Ontario M5S 3E4 (Canada); Rahimipour, M.R. [Department of Ceramic, Materials and Energy Research Center, Karaj 31787-316 (Iran, Islamic Republic of)] [Department of Ceramic, Materials and Energy Research Center, Karaj 31787-316 (Iran, Islamic Republic of)

2013-01-15

277

Analysis of protein glycosylation and phosphorylation using liquid phase separation, protein microarray technology, and mass spectrometry.  

PubMed

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

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

2009-01-01

278

Switchable water: microfluidic investigation of liquid-liquid phase separation mediated by carbon dioxide.  

PubMed

Increase in the ionic strength of water that is mediated by the reaction of carbon dioxide (CO2) with nitrogenous bases is a promising approach toward phase separation in mixtures of water with organic solvents and potentially water purification. Conventional macroscale studies of this complicated process are challenging, due to its occurrence via several consecutive and concurrent steps, mass transfer limitation, and lack of control over gas-liquid interfaces. We report a new microfluidic strategy for fundamental studies of liquid-liquid phase separation mediated by CO2 as well as screening of the efficiency of nitrogenous agents. A single set of microfluidic experiments provided qualitative and quantitative information on the kinetics and completeness of water-tetrahydrofuran phase separation, the minimum amount of CO2 required to complete phase separation, the total CO2 uptake, and the rate of CO2 consumption by the liquid mixture. The efficiency of tertiary diamines with different lengths of alkyl chain was examined in a time- and labor-efficient manner and characterized with the proposed efficiency parameter. A wealth of information obtained using the MF methodology can facilitate the development of new additives for switchable solvents in green chemistry applications. PMID:25079335

Lestari, Gabriella; Abolhasani, Milad; Bennett, Darla; Chase, Preston; Günther, Axel; Kumacheva, Eugenia

2014-08-27

279

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

NASA Astrophysics Data System (ADS)

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.

Aoi, Y.; Tominaga, T.

2013-03-01

280

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

NASA Astrophysics Data System (ADS)

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 dissociative change. The use of Diels-Alder reactions provides completely reversible chemical reactions for this application. The heated fluid can be retransported for storage or implementation as a heat source. The return reaction, releasing the stored heat, can be done spontaneously or in the presence of a catalyst such as Lewis acids. Attention is recommended for the Wentworth-Chen temperature of 250-300 C to minimize the system thermal degradation. Research in the synthesis of diene and dienophile candidate chemicals, into sealed tube and reaction kinetic techniques, and into NMR techniques for identifying further reaction candidates are discussed.

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

1982-12-01

281

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

PubMed Central

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

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

2012-01-01

282

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

NASA Astrophysics Data System (ADS)

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.

Lu, Qing; Kim, Jaegil; Farrell, James D.; Wales, David J.; Straub, John E.

2014-11-01

283

Vector chiral spin liquid phase in quasi-one-dimensional incommensurate helimagnets  

SciTech Connect

Making use of detailed classical Monte Carlo simulations, we study the critical properties of a two-dimensional planar spin model on a square lattice composed by weakly interacting helimagnetic chains. We find a large temperature window where the vector chirality order parameter, <{kappa}{sub jk}> = , the key quantity in multiferroic systems, takes nonzero value in the absence of long-range order or quasi-long-range order. The phase diagram we obtain for different strengths of the interchain coupling clearly shows that the weakness of the interchain interaction plays an essential role in order to observe the vector chiral spin liquid phase in a temperature range of up to now unattained width ({approx_equal}7%, to be compared with {approx_equal}1% or less previously reported for fully frustrated models, the only well-investigated systems unambiguously displaying spin-chirality decoupling). The relevance of our results for three-dimensional models is also discussed.

Cinti, Fabio [Department of Physics, University of Alberta, Edmonton, Alberta, Canada T6G 2J1 (Canada); Department of Physics, University of Florence and CNISM, 50019 Sesto Fiorentino (Finland) (Italy); Cuccoli, Alessandro; Rettori, Angelo [Department of Physics, University of Florence and CNISM, 50019 Sesto Fiorentino (Finland) (Italy)

2011-05-01

284

Morphology and crystal phase evolution of GeO 2 in liquid phase deposition process  

NASA Astrophysics Data System (ADS)

Morphology and crystal phase evolution of GeO 2 in liquid phase deposition (LPD) process is investigated. Rod-like solid phases precipitate out of solution ahead of truncated cube-like phases. SEM, XRD and TEM analyses reveal that the two sorts of solid phases are tetragonal GeO 2 and hexagonal GeO 2, respectively. The tetragonal GeO 2 phases start to experience a re-dissolving process as soon as the hexagonal phases come into being. The prior precipitation of the rod-like phase arises from a relatively low solute saturation of tetragonal GeO 2. Fast growth of a tetragonal GeO 2 phase along [111] direction leads to development of a rod-like shape. The re-dissolving phenomenon does not agree with the classic growth kinetics of crystals but is strongly favored by our calculations based on thermodynamics. The GeO 2 solutes are released in a fluctuant way by germanate ions, which promotes the occurrence of the re-dissolution phenomenon. The current researches open a door for room-temperature LPD growth of not only the hexagonal GeO 2 particles and film but also the one-dimensional tetragonal GeO 2 product.

Jing, Chengbin; Sun, Wei; Wang, Wei; Li, Yi; Chu, Junhao

2012-01-01

285

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

SciTech Connect

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.

Poling, B.E.

1983-07-28

286

Biodegradation of polycyclic aromatic hydrocarbons in a two-liquid-phase system  

SciTech Connect

The use of a two-liquid-phase system consisting of silicone oil and water for biodegrading polycyclic aromatic hydrocarbons (PAHs) was investigated. Biomass determinations indicated that the cells were mainly growing at the silicon oil-water interface. In shaken and aerated systems with PAHs and inoculum, 97% and 80%, respectively, of the total biomass was attached to the silicone phase. PAH concentrations in the silicon phase dropped by a factor 2 to 100 when microorganisms were present. Biodegradation rates in these systems varied from 3.6 to 5 mg PAH-C/L reactor{center_dot}d. In the shaken systems at 28 C, the measured CO{sub 2} production rate was equal to 9.1 mg CO{sub 2}/L reactor{center_dot}d and corresponded to a 50% conversion to CO{sub 2}. In the aerated systems at 10 C, however, only 25% of the PAH-C was converted to CO{sub 2}, resulting in a CO{sub 2} production rate of 0.5 mg CO{sub 2}/L reactor{center_dot}d.

Vanneck, P.; Beeckman, M.; Saeyer, N. De; Verstraete, W. [Univ. of Ghent (Belgium). Centre for Environmental Sanitation; D`Haene, S. [Soils N.V., Zwijndrecht (Belgium)

1995-12-31

287

Gas and liquid phase pyrolysis of tetralin: A reconciliation of apparently contradictory data  

SciTech Connect

The pyrolysis of tetralin under static reactor conditions at 450{degrees}C at 1--3 torr leads to hydrogen loss products (75%), C2 loss products (12%), and neophyl radical rearrangement products (12%). Tetramethylbutane initiated the reaction and the product distribution was unchanged. The rate of reaction is near first order in tetralin accelerated to. The rate is approximately 1/2 order in tetramethybutane. A mechanistic scheme is proposed which involves relatively fast hydrogen atom loss from the 1- or 2-tetralyl radical followed by slow hydrogen atom abstraction or hydrogen atom addition to tetralin, and formation of ring contracted product by reversible neophyl rearrangement of the 2-tetralyl radical followed by rate determining (in that pathway) hydrogen abstraction from tetralin. In the absence of external initiator, initiation by tetralin and termination by hydrogen atom recombination dependent on total pressure, rationalizes the first order behavior. Liquid phase pyrolysis of tatralln at much higher concentrations (ca 20000x) occurs with a rate only three times faster and 1-methylindan is the major product.

Gajewski, J.J.; Paul, G.C.

1991-12-31

288

Gas and liquid phase pyrolysis of tetralin: A reconciliation of apparently contradictory data  

SciTech Connect

The pyrolysis of tetralin under static reactor conditions at 450{degrees}C at 1--3 torr leads to hydrogen loss products (75%), C2 loss products (12%), and neophyl radical rearrangement products (12%). Tetramethylbutane initiated the reaction and the product distribution was unchanged. The rate of reaction is near first order in tetralin accelerated to. The rate is approximately 1/2 order in tetramethybutane. A mechanistic scheme is proposed which involves relatively fast hydrogen atom loss from the 1- or 2-tetralyl radical followed by slow hydrogen atom abstraction or hydrogen atom addition to tetralin, and formation of ring contracted product by reversible neophyl rearrangement of the 2-tetralyl radical followed by rate determining (in that pathway) hydrogen abstraction from tetralin. In the absence of external initiator, initiation by tetralin and termination by hydrogen atom recombination dependent on total pressure, rationalizes the first order behavior. Liquid phase pyrolysis of tatralln at much higher concentrations (ca 20000x) occurs with a rate only three times faster and 1-methylindan is the major product.

Gajewski, J.J.; Paul, G.C.

1991-01-01

289

Nanostructure Particle-Reinforced Transient Liquid Phase Diffusion Bonding: a Comparative Study  

NASA Astrophysics Data System (ADS)

Particle-reinforced aluminum-metal matrix composites (Al-MMCs) are used in many engineering applications, because they provide significant advantages when compared to monolithic aluminum alloys. However, there still exists the need to identify a suitable joining process for these materials, which minimizes particulate disruption and retains the strength of the MMC within the joint region. This study presents a comparison between joint qualities achieved when a monolithic interlayer is used vs when a nanoparticle-reinforced composite interlayer is used during transient liquid phase diffusion bonding of Al-6061 alloy containing 15 vol pct of Al2O3 particles. Examination of the joint region using scanning electron microscopy (SEM), wavelength dispersive spectroscopy (WDS), and X-ray diffraction (XRD) showed the formation of eutectic phases such as Al3Ni, Al9FeNi, and Ni3Si within the joint zone. The results indicate that the addition of nanoparticle reinforcements into the interlayer can be used to improve joint strength and minimize particle segregation.

Cooke, Kavian O.; Khan, Tahir I.; Oliver, Gossett D.

2011-08-01

290

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

SciTech Connect

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.

Olsen, C.S. [Lawrence Berkeley National Lab., CA (United States). Engineering Div.]|[Univ. of California, Berkeley, CA (United States). Materials Science and Mineral Engineering Dept.

1998-05-01

291

Liquid-phase-deposited SiO2 on AlGaAs and its application  

NASA Astrophysics Data System (ADS)

The silicon dioxide (SiO2) on AlGaAs prepared by liquid phase deposition (LPD) at 40 °C has been explored. The LPD-SiO2 film deposition rate is about 67 nm h-1 for the first hour. The leakage current density is about 1.21 × 10-6 A cm-2 at 1 MV cm-1. The interface trap density (Dit) and the flat-band voltage shift (?VFB) are 1.28 × 1012 cm-2 eV-1 and 0.5 V, respectively. After rapid thermal annealing in the N2 ambient at 300 °C for 1 min, the leakage current density, Dit, and ?VFB can be improved to 4.24 × 10-7 A cm-2 at 1 MV cm-1, 1.7 × 1011 cm-2 eV-1, and 0.2 V, respectively. Finally, this study demonstrates the application of the LPD-SiO2 film to the AlGaAs/InGaAs pseudomorphic high-electron-mobility transistor.

Lee, Kuan-Wei; Huang, Jung-Sheng; Lu, Yu-Lin; Lee, Fang-Ming; Lin, Hsien-Cheng; Huang, Jian-Jun; Wang, Yeong-Her

2011-05-01

292

The Utilization of Triton X-100 for Enhanced Two-Dimensional Liquid-Phase Proteomics  

PubMed Central

One of the main challenges in proteomics lies in obtaining a high level of reproducible fractionation of the protein samples. Automated two-dimensional liquid phase fractionation (PF2D) system manufactured by Beckman Coulter provides a process well suited for proteome studies. However, the protein recovery efficiency of such system is low when a protocol recommended by the manufacturer is used for metaproteome profiling of environmental sample. In search of an alternative method that can overcome existing limitations, this study replaced manufacturer's buffers with Triton X-100 during the PF2D evaluation of Escherichia coli K12. Three different Triton X-100 concentrations—0.1%, 0.15%, and 0.2%—were used for the first-dimension protein profiling. As the first-dimension result was at its best in the presence of 0.15% Triton X-100, second-dimension protein fractionation was performed using 0.15% Triton X-100 and the standard buffers. When 0.15% Triton X-100 was used, protein recovery increased as much as tenfold. The elution reliability of 0.15% Triton X-100 determined with ribonuclease A, insulin, ?-lactalbumin, trypsin inhibitor, and cholecystokinin (CCK) affirmed Triton X-100 at 15% can outperform the standard buffers without having adverse effects on samples. This novel use of 0.15% Triton X-100 for PF2D can lead to greater research possibilities in the field of proteomics. PMID:22013380

Kim, Mina; Lee, Sang-Hee; Min, Jiho; Kobayashi, Fumihisa; Um, Hyun-Ju; Kim, Yang-Hoon

2011-01-01

293

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

PubMed Central

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

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

2010-01-01

294

Stability and Liquid-Liquid Phase Separation in Mixed Saturated Lipid Bilayers  

PubMed Central

The phase stability of a fluid lipid bilayer composed of a mixture of DC18PC, (DSPC), and a shorter DCnsDCns PC, with ns from 8 to 17, has been studied using a self-consistent field theory that explicitly includes molecular details and configurational properties of the lipid molecules. Phase separation between two liquid phases was found when there was a sufficient mismatch between the hydrophobic thicknesses of the two bilayers composed entirely of one component or the other. This occurs when ns ? 12 and there is a sufficient concentration of the shorter lipid. The mixture separates into a thin bilayer depleted of DSPC and a thick bilayer enriched in DSPC. Even when there is no phase separation, as in the cases when there is either insufficient concentration of a sufficiently short lipid or any concentration of a lipid with ns > 12, we observe that the effect of the shorter lipid is to increase the susceptibility of the system to fluctuations in the concentration. This is of interest, given that a common motif for the anchoring of proteins to the plasma membrane is via a myristoyl chain, that is, one with 14 carbons. PMID:19450469

Longo, Gabriel S.; Schick, M.; Szleifer, I.

2009-01-01

295

Headspace liquid-phase microextraction of methamphetamine and amphetamine in urine by an aqueous drop.  

PubMed

This study developed a headspace liquid-phase microextraction (LPME) method by using a single aqueous drop in combination with high performance liquid chromatography (HPLC)-UV detection for the determination of methamphetamine (MAP) and amphetamine (AP) in urine samples. The analytes, volatile and basic, were released from sample matrix into the headspace first, and then protonated and dissolved in an aqueous H(3)PO(4) drop hanging in the headspace by a HPLC syringe. After extraction, this drop was directly injected into HPLC. Parameters affecting extraction efficiency were investigated and optimized. This method showed good linearity in the investigated concentration range of 1.0-1500 microg L(-1), repeatability of the extraction (R.S.D.<5%, n=6), and low detection limits (0.3 microg L(-1) for both analytes). Enrichment factors of about 400-fold and 220-fold were achieved for MAP and AP, respectively, at optimum conditions. The feasibility of the method was demonstrated by analyzing human urine samples. PMID:17418185

He, Yi; Vargas, Angelica; Kang, Youn-Jung

2007-04-25

296

Growth of SiO 2 on InP substrate by liquid phase deposition  

NASA Astrophysics Data System (ADS)

We have grown silicon dioxide (SiO 2) on indium phosphorous (InP) substrate by liquid phase deposition (LPD) method. With inserting InP wafer in the treatment solution composed of SiO 2 saturated hydrofluorosilicic acid (H 2SiF 6), 0.1 M boric acid (H 3BO 3) and 1.74 M diluted hydrochloric acid (HCl), the maximum deposition rate and refractive index for the as-grown LPD-SiO 2 film were about 187.5 Å/h and 1.495 under the constant growth temperature of 40 °C. The secondary ion mass spectroscope (SIMS) and energy dispersive X-ray (EDX) confirmed that the elements of silicon, oxygen, and chloride were found in the as-grown LPD-SiO 2 film. On the other hand, the effects of treatment solution incorporated with the hydrogen peroxide (H 2O 2) that can regulate the concentration of OH - ion were also shown in this article. The experimental results represented that the deposition rate decreases with increasing the concentration of hydrogen peroxide due to the reduced concentration of SiO 2 saturated H 2SiF 6 in treatment solution.

Lei, Po Hsun; Yang, Chyi Da

2010-04-01

297

Simultaneous determination of imperatorin and its metabolite xanthotoxol in rat plasma by using HPLC-ESI-MS coupled with hollow fiber liquid phase microextraction.  

PubMed

The objective of the present study was to develop a new method for the simultaneous quantitation of imperatorin and its metabolite xanthotoxol in rat plasma. The samples were prepared with hollow fiber liquid phase microextraction (HF-LPME). The optimized extraction procedure was acquired by assessing extraction solvent, length of the fiber, agitation rate, extraction temperature and time. A comparison of sample pretreatment ways between HF-LPME and deproteinization with methanol was performed, which demonstrated less ion suppression and better sensitivity of HF-LPME. Analytes were separated on a C18 column with a gradient elution consisted of methanol and water containing 1mmol/L ammonium acetate. The detection was accomplished by electrospray ionization (ESI) source operating in the positive ionization mode. Selected-multiple-reaction monitoring (SMRM) scanning was employed, which guaranteed a higher sensitivity compared with MRM mode. Calibration curves were linear over investigated ranges with correlation coefficients greater than 0.9979. Precision varied from 0.26% to 14%, and the accuracy varied within ±5.5%. The developed method was successfully applied to the pharmacokinetic research of imperatorin and its metabolite xanthotoxol after oral administration of imperatorin to rats. PMID:24342512

Zhang, Juan; Zhang, Min; Fu, Shan; Li, Tao; Wang, Shuang; Zhao, Minmin; Ding, Weijing; Wang, Chunying; Wang, Qiao

2014-01-15

298

Quantification of tetramethyl-terephthalic acid in rat liver, spleen and urine matrices by liquid-liquid phase extraction and HPLC-photodiode array detection.  

PubMed

Tetramethyl-terephthalate (TMT) is the constitutive linker of the flexible porous iron(III) carboxylate Metal Organic Framework (MOF) MIL-88B_4CH? based drug nanocarrier (MIL stands for Material from Institut Lavoisier). A method for the determination of the concentration of tetramethyl-terephthalic acid has been developed in different biological rat matrices (liver, spleen and urine) using a liquid-liquid phase extraction and high-performance liquid chromatography (HPLC) coupled to photodiode array detection with 4-aminosalicylic acid as internal standard. The extraction conditions of TMT have been varied from urine to tissue depending on the complexity of the biological matrices. The chromatographic separation was performed with a gradient elution. In all matrices, the limits of detection and quantification of TMT was 0.01 and 0.05 ?g ml?¹, respectively. The recovery of the TMT reached 86, 89 and 97% for urine, spleen and liver tissues, respectively. The linearity of the calibration curves in urine and tissues was satisfactory in all cases as evidenced by correlation coefficients >0.990. The within-day and between-day precisions were <15% (n=6) and the accuracy ranged in all cases between 86 and 103%. This method has finally allowed the quantification of TMT in rat urine and in tissue samples of rats administered intravenously with iron(III) tetramethyltherepthalate MIL-88B_4CH? nanoparticles. PMID:22608098

Baati, Tarek; Horcajada, Patricia; David, Olivier; Gref, Ruxandra; Couvreur, Patrick; Serre, Christian

2012-01-01

299

Liquid-phase microextraction and GC for the determination of primary, secondary and tertiary aromatic amines as their iodo-derivatives.  

PubMed

Presence of iodine in aromatic amines, introduced by their reaction with iodine, and other electron withdrawing substituents such as chlorine and nitro, has been found to afford excellent liquid-phase microextraction (LPME) in toluene and separation by gas chromatography in the determination of primary, secondary and tertiary aromatic amines. The effect is due to decreased basic nature of amines when electronegative substituents are present. Single drop microextraction (SDME) of the amines in 2mul of toluene and injection of the whole extract into GC, or LPME into 50mul of toluene and injection of 2mul of extract, were used. LPME has been found more robust and to give better extraction in shorter period than SDME. In SDME-GC-FID, the average correlation coefficient was 0.9939 and average limit of detection 25mugl(-1) (range 12-61mugl(-1)) whereas the corresponding values in LPME-GC-MS were, respectively, 0.9953 and 33ngl(-1) (range 18-60ngl(-1)). The method has been applied to determine aromatic amines in river water, dye factory effluents and food dye stuffs. The LPME was found as robust, rugged and simple extraction method. PMID:19073089

Reddy-Noone, Kishan; Jain, Archana; Verma, Krishna K

2007-10-15

300

Determination of phenols in environmental water samples by two-step liquid-phase microextraction coupled with high performance liquid chromatography.  

PubMed

In this work, a two-step liquid-phase microextraction (LPME) method was presented for the extraction of phenols in environmental water samples. Firstly, the polar phenol in water samples (donor phase) was transferred to 1-octanol (extraction mesophase) by magnetic stirring-assisted LPME. Subsequently, target analytes in the 1-octanol was back extracted into 0.1 mol/L sodium hydroxide solution (acceptor phase) by vortex-assisted LPME. By combination of the two-step LPME, the enrichment factors were multiplied. The main features of this two-step LPME for phenols lie in the following aspects. Firstly, the extraction can be accomplished within relatively short time (ca. 20 min). Secondly, it was compatible with HPLC analysis, avoiding derivatization step that is generally necessary for GC analysis. Thirdly, high enrichment factors (296-954 fold) could be obtained for these analytes. Under the optimized conditions, the linearities were 10-1000, 1-500, 1-500, 5-500 and 1-500 ng/mL for different phenols with all regression coefficients higher than 0.9985. The limits of detection were in the range from 0.3 to 3.0 ng/mL for these analytes. Intra-and inter-day relative standard deviations were below 7.6%, indicating a good precision of the proposed method. PMID:21962686

Zhang, Ping-Ping; Shi, Zhi-Guo; Feng, Yu-Qi

2011-10-15

301

Thermodynamic Model of Liquid-Liquid Phase Equilibrium in Solutions of Alkanethiol-Coated Nanoparticles  

E-print Network

A thermodynamic model for a mixture of alkanethiol-coated nanoparticles (NPs) and low molecular weight (non-polymeric) solvent is developed, and calculations of liquid-liquid phase equilibrium for different values of NP core radius, alkanethiol chain length, solvent molar volume and alkanethiol-solvent interaction parameter, are presented. The model takes into account the swelling of the organic coronas and the dispersion of particles with swollen coronas in the solvent. The energetic interaction between alkyl chains and solvent is considered, both within the corona and between the outer alkyl segments and free solvent. Swelling involves mixing of alkanethiol chains and solvent in the corona and stretching of the organic chains. Dispersion considers an entropic contribution based on Carnahan Starling equation of state and an enthalpic term calculated considering the surface contacts between alkyl segments placed in the external boundary of the corona and the molecules of free solvent. Two different kinds of phase equilibrium are found. One of them, observed at high values of the interaction parameter, is the typical liquid-liquid equilibrium for compact NPs in a poor solvent where a complete phase separation is observed when cooling (increasing the interaction parameter). The second liquid-liquid equilibrium is observed at low values of the interaction parameter, where swelling of coronas is favored. In this region two different phases co-exist, one more concentrated in NPs that exhibit relatively compact coronas and the other one more diluted in NPs with extended coronas. In diluted solutions of NPs the deswelling of the fully extended coronas takes place abruptly in a very small temperature range, leading to a solution of compact NPs. This critical transition might find practical applications similar to those found for the abrupt shrinkage of hydrogels at a critical temperature.

Ezequiel R. Soule; Cristina E. Hoppe; Julio Borrajo; Roberto J. J. Williams

2013-11-21

302

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

NASA Astrophysics Data System (ADS)

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.

Santos, Bjorn Sanchez

303

Liquid-phase binding assay of alpha-fetoprotein using DNA-coupled antibody and capillary chip electrophoresis.  

PubMed

An immunoassay using DNA-coupled antibody for bound/free separation in a liquid-phase binding assay format is described. Anti-alpha-fetoprotein monoclonal antibody was conjugated with DNA, mixed with alpha-fetoprotein (AFP), and incubated, and then 1 muL of the mixture was applied to capillary electrophoresis on a microchip. The DNA molecule of the antibody-DNA conjugate and the DNA-conjugated immune complex peak were detectable fluorophotometrically using intercalator dye within 90 s, whereas the Alexa-labeled antibody was detected as a broad and slower migrating peak. The electrophoretic mobility of the immune complex could be optimized for resolution and sharpness by changing the length of the DNA coupled to the antibody. The detection limit of AFP was approximately 300 pM in a sample. This immunoassay method utilizing a liquid-phase binding assay format is simple and convenient for antigen measurements on microchips. PMID:16131068

Kawabata, Tomohisa; Watanabe, Mitsuo; Nakamura, Kenji; Satomura, Shinji

2005-09-01

304

Carrier mediated hollow fiber liquid phase microextraction combined with HPLC–UV for preconcentration and determination of some tetracycline antibiotics  

Microsoft Academic Search

In the present study, a simple and efficient preconcentration method was developed using carrier mediated three phase liquid phase microextraction prior to HPLC–UV for simultaneous extraction and determination of trace amounts of highly hydrophilic tetracycline antibiotics including tetracycline (TCN), oxytetracycline (OTCN) and doxycycline (DCN) in bovine milk, human plasma and water samples. For extraction, 11.0mL of the aqueous sample containing

Shahab Shariati; Yadollah Yamini; Ali Esrafili

2009-01-01

305

The liquid phase hydrogenation of benzene and substituted alkylbenzenes over a nickel catalyst in a semi-batch reactor  

Microsoft Academic Search

The liquid phase hydrogenation kinetics of benzene, toluene, ethylbenzene and cumene was studied in a three-phase semibatch reactor at pressures of 20–40 bar and at temperatures of 95–140°C. The experimental kinetics was described with a rate equation based on rapid adsorption and desorption steps and slow consecutive hydrogen steps.A pseudo-homogeneous model neglecting the diffusion resistances in the catalyst particles was

Sami Toppinen; Tiina-Kaisa Rantakylä; Tapio Salml; Juhani Aittamaa

1997-01-01

306

An easy-to-use heterogeneous promoted zirconia catalyst for Knoevenagel condensation in liquid phase under solvent-free conditions  

Microsoft Academic Search

Knoevenagel condensation of various aliphatic, aromatic and heterocyclic aldehydes with malononitrile was carried out in the liquid phase in one step by employing a sulfate-ion promoted zirconia solid acid catalyst. This catalyst facilitates the reaction under solvent-free conditions at moderate temperatures providing excellent yields of the products. The sulfate-ion promoted zirconia catalyst was synthesized by immersing a finely powdered hydrous

Benjaram M. Reddy; Meghshyam K. Patil; Komateedi N. Rao; Gunugunuri K. Reddy

2006-01-01

307

Rapid and Simultaneous Study on Drug–Protein Binding of Four Furocoumarins by Hollow Fiber Liquid Phase Microextraction  

Microsoft Academic Search

Hollow fiber liquid–liquid phase microextraction followed by high-performance liquid chromatography was employed to research\\u000a the binding of four furocoumarin compounds (psoralen, oxypeucedanin, imperatorin and isoimperatorin) to bovine serum albumin.\\u000a The results reveal that the percent of drug–protein binding did not rely on the furocoumarins and protein concentrations,\\u000a and four furocoumarins scarcely competed for protein binding sites. The protein-binding percents of

Shuang Hu; Yan Jie Zhang; Xiao Hong Bai

308

Lead contamination of a transient liquid-phase-processed Sn-Bi lead-free solder paste  

Microsoft Academic Search

The influence of Pb contamination on the solidification behavior of a transient liquid-phase powder-processed Sn-Bi solder\\u000a paste has been studied using differential scanning calorimetry. The development of low-temperature ternary reactions was found\\u000a to be very sensitive to both the Pb and Bi content of the solder. Solders with high Bi content favored the formation of the\\u000a ternary eutectic reaction. Solders

M. Whitney; S. F. Corbin

2006-01-01

309

Reliability study of Au-In transient liquid phase bonding for SiC power semiconductor packaging  

Microsoft Academic Search

Transient liquid phase (TLP) bonding is a promising advanced die-attach technique for wide-bandgap power semiconductor and high-temperature packaging. TLP bonding advances modern soldering techniques by raising the melting point to over 500°C without detrimental high-lead materials. The bond also has greater reliability and rigidity due in part to a bonding temperature of 200°C that drastically lowers the peak bond stresses.

Brian Grummel; Habib A. Mustain; Z. John Shen; Allen R. Hefner

2011-01-01

310

Comparison of Au-In Transient Liquid Phase Bonding Designs for SiC Power Semiconductor Device Packaging  

Microsoft Academic Search

This work is an investigation of transient liquid phase {(TLP)} bonding for high-temperature die-attach and packaging for wide-bandgap power semiconductors, particularly {SiC.} Current die attach materials bottleneck the capabilities of {SiC} power devices due to their temperature operation range and reliability. Traditional tin-lead solder has a melting point of only {183°C} and is inadequate for the operational temperature range of

Brian J. Grummel; Habib A. Mustain; Z. John Shen; Allen R. Hefner

2011-01-01

311

Preparation, structure and crystallinity of chitosan nano-fibers by a solid–liquid phase separation technique  

Microsoft Academic Search

Chitosan acetate nano-fibers were fabricated via a solid–liquid phase separation technique. The chitosan acetate structure was influenced by phase separation temperature, chitosan concentration and acetic acid concentration. Uniform nano-fibrous chitosan acetate of 50–500nm in diameter was engineered at 0.05% (w\\/v) chitosan and 0.025% (v\\/v) acetic acid in liquid nitrogen, as opposed to film-shape and micro-fibrous structure at ?18°C and ?80°C

Jianhao Zhao; Wanqing Han; Haodong Chen; Mei Tu; Rong Zeng; Yunfeng Shi; Zhengang Cha; Changren Zhou

2011-01-01

312

Enhanced degradation of bioremediation residues in petroleum-contaminated soil using a two-liquid-phase bioslurry reactor  

Microsoft Academic Search

A study was performed to determine the potential of two-liquid-phase (TLP) bioslurry reactors using silicon oil as solvent for degradation of residual contaminants in petroleum-contaminated soil. The residues were characterized by gas chromatography–mass spectrometry and electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. This allowed for the identification of a mixture of residual biomarkers, metabolic byproducts, oxygenated and hetero-polynuclear

Mang Lu; Zhongzhi Zhang; Shanshan Sun; Qinfang Wang; Weizhang Zhong

2009-01-01

313

Thermal energy storage with chemical reaction of NaI-NH3 system. I - Region of liquid phase  

NASA Astrophysics Data System (ADS)

It is shown that a liquid phase in the solid sodium iodide-gaseous ammonia reaction offers a thermal energy storage medium at temperatures suitable for air conditioning. The density of the liquid ammoniate varies depending on temperature and pressure, but the maximum value observed in the present experiments was 1.7 g/cu cm. The liquid region extends to temperatures below zero under higher pressure than the atmospheric, allowing a refrigerator employing the system to operate under possitive pressures.

Fujiwara, I.; Nakashima, Y.; Goto, T.

314

Effect of residual stress on the strength of an alumina–steel joint by partial transient liquid phase (PTLP) brazing  

Microsoft Academic Search

The effect of residual stress on the strength of joints made between alumina and stainless using partial transient liquid phase (PTLP) brazing with the Ni of an 80Ni20Cr core interlayer was studied. It was found that the residual stress caused by the thermal expansion mismatch between alumina (Al2O3) and stainless steel-304 (SS304) deteriorated the Al2O3–SS304 joints severely compared to Al2O3–Al2O3

J. X Zhang; R. S Chandel; Y. Z Chen; H. P Seow

2002-01-01

315

Thermodynamic and kinetic studies on reversible liquid-phase Diels Alder reaction between maleic anhydride and 2-methyl furan  

Microsoft Academic Search

The liquid phase reaction between maleic anhydride and 1-methyl-furan leads to an exothermic cycloaddition. The reaction enthalpy,\\u000a the rate constant and the equilibrium constant are evaluated with good precision by a method of analysis using thermal data\\u000a and a dynamic model based on physical properties. The mathematical models that are presented here in a simple way (first-order\\u000a system) represent the

N. Balbi; B. Khoumeri

1994-01-01

316

Comparison of Methods to Obtain a Liquid Phase in Marine Sediment Toxicity Bioassays with Paracentrotus lividus Sea Urchin Embryos  

Microsoft Academic Search

Sediment toxicity bioassays using planktonic organisms are widespread tools in environmental quality assessment, but they\\u000a have limitations because the method for extracting and diluting the liquid phase may affect the final toxicity. The present\\u000a study compares the toxicity on sea urchin embryos and larvae of elutriates and pore water obtained from intertidal sediments\\u000a by various methods. The effects of mixing

R. Beiras

2002-01-01

317

Effect of Pressure on Discharge Initiation and Chemical Reaction in a Liquid-Phase Electrical Discharge Reactor  

Microsoft Academic Search

The effect of pressure on liquid-phase electrical discharges was investigated by using a stainless steel high-pressure reactor combined with a high-voltage pulse forming network. The initiation breakdown voltage was obtained under various pressures up to 1380 kPa (200 lb\\/in2 ). The discharge characteristics including current and voltage waveforms as well as power per pulse were determined. The effect of pressure

Kai-Yuan Shih; Radu Burlica; Wright C. Finney; Bruce R. Locke

2009-01-01

318

Light Extraction Efficiency Enhancement of GaN Blue LED by Liquid-Phase-Deposited ZnO Rods  

Microsoft Academic Search

We investigate the light extraction efficiency of a GaN light-emitting diode (LED) by using liquid-phase-deposited ZnO rods at near-room temperature. Zinc nitrate and hexamethylenetetramine were used as the deposition precursors. Compared with the conventional GaN LED, the optical power output of the GaN LED with crystalline ZnO rods on its surface has about 1.6 times enhancement.

Ming-Kwei Lee; Chen-Lin Ho; Po-Chun Chen

2008-01-01

319

Effect of bonding temperature on transient liquid phase bonding behavior of a Ni-based oxide dispersion-strengthened superalloy  

Microsoft Academic Search

The effect of joining temperature on the transient liquid phase (TLP) bonding of MA758 superalloy was investigated. The TLP\\u000a bonds were made at temperatures of 1100 and 1200 °C. Analysis was undertaken to determine the changes within the joint microstructure.\\u000a The bonding temperature affected the extent of parent metal dissolution, the time for isothermal solidification, and the attainment\\u000a of microstructural

R. K. Saha; T. I. Khan

2006-01-01

320

Novel multifunctional acceptor phase additive of water-miscible ionic liquid in hollow-fiber protected liquid phase microextraction  

Microsoft Academic Search

In this paper, water-miscible ionic liquid (IL) such as 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) is introduced for the first time as a novel multifunctional acceptor phase additive in hollow-fiber protected liquid phase microextraction (HF-LPME). For investigating the performances of [BMIM]Cl, it was respectively mixed with NaOH, HCl and deionized water. And their extraction performance was preliminary evaluated with alkaline compounds (clenbuterol, metoprolol,

Wei Liu; Zhenyi Wei; Qing Zhang; Fang Wu; Zian Lin; Qiaomei Lu; Fen Lin; Guonan Chen; Lan Zhang

321

Influence of gangue existing states in iron ores on the formation and flow of liquid phase during sintering  

NASA Astrophysics Data System (ADS)

Gangue existing states largely affect the high-temperature characteristics of iron ores. Using a micro-sintering method and scanning electron microscopy, the effects of gangue content, gangue type, and gangue size on the assimilation characteristics and fluidity of liquid phase of five different iron ores were analyzed in this study. Next, the mechanism based on the reaction between gangues and sintering materials was unraveled. The results show that, as the SiO2 levels increase in the iron ores, the lowest assimilation temperature (LAT) decreases, whereas the index of fluidity of liquid phase (IFL) increases. Below 1.5wt%, Al2O3 benefits the assimilation reaction, but higher concentrations proved detrimental. Larger quartz particles increase the SiO2 levels at the local reaction interface between the iron ore and CaO, thereby reducing the LAT. Quartz-gibbsite is more conductive to assimilation than kaolin. Quartz-gibbsite and kaolin gangues encourage the formation of liquid-phase low-Al2O3-SFCA with high IFL and high-Al2O3-SFCA with low IFL, respectively.

Zhang, Guo-liang; Wu, Sheng-li; Chen, Shao-guo; Su, Bo; Que, Zhi-gang; Hou, Chao-gang

2014-10-01

322

Characterization of the texturing of YBa2Cu3O7-? in the presence of liquid phase additives  

NASA Astrophysics Data System (ADS)

Grain growth and texturing of YBa2Cu3O7-? is greatly influenced by the presence of liquid phase additives during sintering. Oxides such as TiO2, SiO2, Bi2O3, and Pr6O11 were incorporated into the liquid phase during the sintering of YBa2Cu3O7-? (123) by use of grain boundary diffusion couples and the microstructure was analyzed using scanning electron microscopy/electron dispersive spectroscopy. Exaggerated grain growth and domain formation was observed in bulk specimens. Differential thermal analysis and real time dynamic x-ray diffraction were used to determine reaction sequencing. The ability and extent of domain formation was determined for 123 samples coupled with impurity oxides to be a function of sintering temperature (940 980°) and oxygen partial pressure. Enhanced texturing was observed at low PO2 atmospheres. The addition of Bi2O3 and TiO2 was shown to degrade dc magnetic susceptibility of 123 whereas SiO2 and Pr6O11 enhanced it. The domain formation and texturing takes place in the bulk for 123 at temperatures of 980°C or below (i.e. well below the peritectic decomposition temperature) by the interaction of an impurity doped liquid phase followed by a precipitation and exaggerated grain growth.

Fagan, J. G.; Partis, D. A.; Richmond-Hope, J. A.; Amarakoon, V. R. W.

1994-11-01

323

Activity and Osmotic Coefficients from the Emf of Liquid Membrane Cells. X. Tris(Ethylenediamine) Cobalt(III) Nitrate, Perchlorate, and Chloride  

Microsoft Academic Search

Activity coefficients of [Co(en)3](NO3)3 and [Co(en)3](ClO4)3, to be compared with [Co(en)3]Cl3 and the corresponding lanthanum salts previously studied, are determined. [Co(en)3]Cl3 data are revised. Ion interaction strengths vary in the same order found for La3+, i.e., as if nitrate and perchlorate ions were of smaller and larger size, respectively, than chloride ions; however, the differences are much smaller than in

Francesco Malatesta

2002-01-01

324

Gas-liquid chromatography measurements of activity coefficients at infinite dilution of hydrocarbons and alkanols in 1-alkyl-3-methylimidazolium bis(oxalato)borate  

Microsoft Academic Search

The activity coefficients at infinite dilution, ?i? for various solutes: alkanes, cycloalkanes, 1-alkenes, 1-alkynes, benzene, alkylbenzenes, and alcohols in the ionic liquids 1-butyl-3-methylimidazolium bis(oxalato)borate [BMIM][BOB] and 1-hexyl-3-methyl-imidazolium bis(oxalato)borate [HMIM][BOB] have been determined by gas-liquid chromatography at the temperatures ranging from 308 to 348K. The partial molar excess enthalpies at infinite dilution HiE,? of the solutes in the ionic liquids were

Pei-Fang Yan; Miao Yang; Chang-Ping Li; Xiu-Mei Liu; Zhi-Cheng Tan; Urs Welz-Biermann

2010-01-01

325

On inferring liquid-liquid phase boundaries and tie lines from ternary mixture light scattering  

NASA Astrophysics Data System (ADS)

We investigate the possibility of using light scattering data in the single-phase regions of a ternary liquid mixture phase diagram to infer ternary mixture coexistence curves, and to infer tie lines joining the compositions of isotropic liquid phases in thermodynamic equilibrium. Previous analyses of a nonlinear light scattering partial differential equation (LSPDE) show that it provides for reconstruction of ternary [D. Ross, G. Thurston, and C. Lutzer, J. Chem. Phys. 129, 064106 (2008); C. Wahle, D. Ross, and G. Thurston, J. Chem. Phys. 137, 034201 (2012)] and quaternary [C. Wahle, D. Ross, and G. Thurston, J. Chem. Phys. 137, 034202 (2012)] mixing free energies from light scattering data, and that if the coexistence curves are already known, it can also yield ternary tie lines and triangles [D. Ross, G. Thurston, and C. Lutzer, J. Chem. Phys. 129, 064106 (2008)]. Here, we show that the LSPDE can be used more generally, to infer phase boundaries and tie lines from light scattering data in the single-phase region, without prior knowledge of the coexistence curve, if the single-phase region is connected. The method extends the fact that the reciprocal light scattering intensity approaches zero at the thermodynamic spinodal. Expressing the free energy as the sum of ideal and excess parts leads to a natural family of Padé approximants for the reciprocal Rayleigh ratio. To test the method, we evaluate the single-phase reciprocal Rayleigh ratio resulting from the mean-field, regular solution model on a fine grid. We then use a low-order approximant to extrapolate the reciprocal Rayleigh ratio into metastable and unstable regions. In the metastable zone, the extrapolation estimates light scattering prior to nucleation and growth of a new phase. In the unstable zone, the extrapolation produces a negative function that in the present context is a computational convenience. The original and extrapolated reciprocal light scattering are jointly used as input to solving the LSPDE to deduce the mixing free energy and its convex hull. When projected onto the composition triangle, the boundary of the convexified part of the free energy is the phase boundary, and lines on the convexified region along which the second directional derivative is zero are the tie lines. We find that the tie lines and phase boundaries so deduced agree well with their exact values. This work is a step toward developing methods for inferring phase boundaries from real light scattering intensities measured with noise, from mixtures having compositions on a coarser grid.

Wahle, Chris W.; Ross, David S.; Thurston, George M.

2012-07-01

326

Liquid phase sintered composite solders for next generation thermal interface applications  

NASA Astrophysics Data System (ADS)

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.

Liu, Jia

327

Effect of micro-gravity on the microstructural evolution during liquid phase sintering  

NASA Astrophysics Data System (ADS)

The effect of gravity on the evolution of microstructure during liquid phase sintering was studied using Ni-Fe tungsten heavy alloy, for varying sintering times, compositions, and gravity conditions (microgravity and normal gravity). A serial sectioning of the samples was carried out and the three dimensional microstructure was reconstructed. The microstructure was quantified using volume-probe techniques developed in the course of this research. Computer codes were written to extract descriptors of spatial arrangement of grains from the image data. It was seen that the microstructure in gravity evolves as just a scale factor change with sintering time whereas it is not so in microgravity. The scale factor change in gravity was seen in the evolution of grain size distribution function, radial distribution function and 1st, 2nd and 3rd nearest neighbor distribution functions. In specimens processed in both gravity and microgravity environment there are practically no isolated grains suspended in the matrix. This was expected in gravity where the grains have to contact each other to provide normal force to balance gravity, but it was surprising to see this in microgravity. At a given sintering time, the coordination number in microgravity was significantly lower than that in gravity. In microgravity, the coordination number remains constant whereas in gravity, it increases with time. This increase is attributed to grain shape accommodation. A strong correlation was found between the coordination number and the mean surface area of grains forming that coordination which was expressed by a linear equation. Inspite of significant differences between the volume fractions of gravity and microgravity samples, the 1st and 2nd 3D nearest neighbor distances are only a scale change, with the scale factor being the mean grain size. In the initial stages of sintering, the kinetics of grain growth is slower in microgravity than in gravity environment resulting in a significant difference in the grain sizes. However, the difference in grain size after 120 minutes of sintering becomes insignificant. The observed difference in rates of grain growth at lower times (upto 1 minute) is attributed to the effect of coalescence. It was observed that there is no densification with time in microgravity though this effect is seen in gravity.

Tewari, Asim

328

Erbium doping in InGaAsP grown by liquid-phase epitaxy  

NASA Astrophysics Data System (ADS)

The Er-doped InGaAsP epitaxial layers lattice-matched to InP with wavelengths of 1.29 and 1.55 ?m have been grown by liquid-phase epitaxy. When the Er amount doped in the InGaAsP growth solution is above 0.32 wt %, it will have a fairly rough surface morphology with many extensive deposits of erbium hydride and oxide. The lattice mismatch normal to the wafer surface between InGaAsP layer and InP substrate decreases linearly with the Er weight percent in the grown solution. From the wavelength-dispersive-x-ray-spectrometer analysis, we find the solid composition of the In1-xGaxAsyP1-y layer has been changed and may be due to the formation of microparticles of Er compounds, such as ErAs or ErP. This inference is also supported by photoluminescence (PL) measurements which show that the PL peak wavelength decreases with increasing Er wt %. The full width at half maximum of PL peak associated with the near band-gap transition has been effectively reduced and exhibits the narrowest value of 9.1 and 6.3 meV for the 1.29- and 1.55-?m-wavelength InGaAsP layers in the presence of Er. In addition, the carrier concentration of Er-doped InGaAsP layers are around 3-30×1014 cm-3 and is one to two orders of magnitude lower than those of undoped layers. These results can be attributed to the donor gettering by the rare-earth element of Er. The Er-related luminescence lines locate between 1.503 and 1.528 ?m which differ from those previously reported at ˜1.54 ?m and can only be observed for the 1.29-?m but not for the 1.55-?m-wavelength InGaAsP layers.

Wu, Meng-Chyi; Chen, En-Hsing; Chin, Tsung-Shune; Tu, Yuan-Kuang

1992-01-01

329

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

PubMed

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

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

2010-03-26

330

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

NASA Astrophysics Data System (ADS)

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 fluorescent product, 2,5-dihydroxybenzoic acid (2,5-DHBA), which is determined by reverse phase HPLC and fluorescence detection. The atmospheric OH concentration ( (OH)) is inferred from the resulting 2,5-DHBA amount in the aqueous scrubbing solution, fraction of 2,5-DHBA in the products, air sampling flow rate, sampling time, local pressure and temperature, etc. HPLC separation efficiency and fluorescence detection sensitivity for 2,5-DHBA have been studied. The results indicate that: the reagent blank can be controlled by suitable recrystallization; pH affects both separation and detection processes; the fluorometer should be adjusted to reach its highest signal-to-noise ratio by light source selection, flow cell size selection, wavelength selection, etc. Preliminary column switch experiments reveal the possibility to automate the whole sampling and detection system to enhance the temporal resolution. During an intercomparison of tropospheric OH measurement techniques at the Caribou site, CO (relatively unpolluted air) in Fall 1993, overlapping data were obtained with long path absorption and ion-assisted coupled with MS methods. LPS -HPLC day-time (OH) s, which range from {< }10^6 to 6times10 ^6 radicals/cm^3, agree well with those derived from the other two methods, especially the latter. LPS-HPLC (OH) depends linearly on the combined effects of solar flux, ozone and water vapor, however, it has a nonlinear dependence on NO _{x} and hydrocarbons. These results are consistent with that predicted from photochemical models. Experimental results and model calculations indicate that there is negligible or only slight interference from atmospheric species, including HO_2, ozone, NO_{rm x} and hydrocarbons.

Chen, Xiaohui

331

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...

332

Mean activity coefficients for the simple electrolyte in aqueous mixtures of polyelectrolyte and simple electrolyte. V. Common counterion mixtures of alkali-metal dextransulfates with alkali metal chlorides.  

PubMed

Mean molal activity coefficients of simple electrolyte in aqueous solutions of Li, Na, K or Cs salts of dextransulfate (DS) with added LiCl, NaCl, KCl or CsCl are reported. The measurements were carried out by means of an electrochemical cell method using a cation exchange membrane as cation selective electrode and Ag/AgCl electrodes. For LiDS-LiCl, NaDS-NaCl and CsDS-CsCl systems the polymer concentration, mp, was varied from 0.0088 to 0.113 m and at a given mp the ratio X of the polymer to salt concentration was varied from 0.5 to 16. Due to the insolubility of KDS in high concentration of KCl, the measurements on KDS-KCl system were performed in the mp range of 0.0088--0.089 m and some of the smaller X values were omitted. The activity coefficient results are compared to Manning's limiting laws, the additivity rule, and to new limiting laws. The additivity rule can give an excellent representation of the data for all mp values when gammap is used as an adjustable parameter. PMID:687767

Joshi, Y M; Kwak, J C

1978-07-01

333

Novelties of microwave assisted liquid–liquid phase transfer catalysis in enhancement of rates and selectivities in alkylation of phenols under mild conditions  

Microsoft Academic Search

The formation of phenolic ethers is accelerated remarkably upon microwave irradiation under the mild power input of 40 W using liquid–liquid phase transfer catalysis. It also leads to improved selectivities.

Ganapati D Yadav; Priyal M Bisht

2004-01-01

334

One-dimensional virus transport in porous media with time-dependent inactivation rate coefficients  

Microsoft Academic Search

A model for virus transport in one-dimensional, homogeneous, saturated porous media is developed, accounting for virus sorption and inactivation of liquid phase and adsorbed viruses with different time dependent rate coefficients. The virus inactivation process is represented by a pseudo first-order rate expression. The pseudo first-order approximation is shown to simulate available experimental data from three virus inactivation batch studies

Youn Sim; Constantinos V. Chrysikopoulos

1996-01-01

335

Liquid phase epitaxial growth of InGaAs on InP using rare-earth-treated and Paul R. Bergerb)  

E-print Network

Liquid phase epitaxial growth of InGaAs on InP using rare-earth-treated melts Wei Gaoa) and Paul R-doped InP substrates. The growths were performed by liquid phase epitaxy LPE using rare-earth-doped melts in a graphite boat. The rare-earth elements studied were Yb, Gd and Er which act as gettering agents

336

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

NASA Astrophysics Data System (ADS)

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.

Zhou, Xinquan; Doup, Benjamin; Sun, Xiaodong

2013-12-01

337

Characterization of transparent conducting p-type nickel oxide films grown by liquid phase deposition on glass  

NASA Astrophysics Data System (ADS)

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.

Lee, Ming-Kwei; Lai, Yen-Ting

2013-02-01

338

Study of the Au\\/In Reaction for Transient Liquid-Phase Bonding and 3D Chip Stacking  

Microsoft Academic Search

The latest three-dimensional (3D) chip-stacking technology requires the repeated stacking of additional layers without remelting\\u000a the joints that have been formed at lower levels of the stack. This can be achieved by transient liquid-phase (TLP) bonding\\u000a whereby intermetallic joints can be formed at a lower temperature and withstand subsequent higher-temperature processes. In\\u000a order to develop a robust low-temperature Au\\/In TLP

W. Zhang; W. Ruythooren

2008-01-01

339

Single-channel shear horizontal surface acoustic wave sensor for the identification of liquid-phase substances  

NASA Astrophysics Data System (ADS)

The principal possibility of liquid-phase substances recognition with the aid of a single-channel sensor operating on a shear horizontal surface acoustic wave (SH-SAW) delay line has been experimentally demonstrated. The SH-SAW sensor was manufactured as a SAW delay line based on a layered structure on 36° YX LiTaO3 crystal substrate. The response signal is related to the analyt-induced change in a pulse characteristic obtained by the frequency-to-time domain transformation of one of the measured S-parameters.

Kryshtal, R. G.; Medved, A. V.

2010-01-01

340

Primary structures of neuropeptides isolated from the corpora cardiaca of various cetonid beetle species determined by pulsed-liquid phase sequencing and tandem fast atom bombardment mass spectrometry.  

PubMed

A peptide with the same retention time on gradient reversed-phase high-performance liquid chromatography was present in the corpora cardiaca of 5 scarabaeid beetles, subfamily Cetoniinae: the three fruit beetle species Pachnoda marginata, P. sinuata and P. aemulae and the two protea beetle species Trichostetha fascularis and T. albopicta. Crude corpora cardiaca material from P. sinuata had a small hypertrehalosaemic effect in American cockroaches and a very weak hyperlipaemic activity in migratory locusts. Injections into P. sinuata caused hypertrehalosaemia when a dose of 1.0 corpora cardiaca equivalents was injected. An identical neuropeptide was isolated, by RP-HPLC, and sequenced by pulsed-liquid phase sequencing employing Edman chemistry after enzymically deblocking the N-terminal 5-oxopyrrolidine-2-carboxylic acid residue, as well as by collision-induced decomposition tandem fast atom bombardment mass spectrometry. The peptide is a blocked octapeptide: Glu-Leu-Asn-Tyr-Ser-Pro-Asp-TrpNH2, previously designated Mem-CC. The synthetic peptide is able to elicit haemolymph carbohydrates in P. sinuata upon injection of low doses. Activity studies using synthetic analogues of this peptide revealed that Tyr4 may be important for receptor recognition/binding. The peptide is synthesized in intrinsic cells of the corpus cardiacum as shown by in vitro incorporation of [3H]Trp and [14C]Tyr in Mem-CC. PMID:1586453

Gäde, G; Lopata, A; Kellner, R; Rinehart, K L

1992-03-01

341

Factor Scores, Structure Coefficients, and Communality Coefficients  

ERIC Educational Resources Information Center

This paper presents heuristic explanations of factor scores, structure coefficients, and communality coefficients. Common misconceptions regarding these topics are clarified. In addition, (a) the regression (b) Bartlett, (c) Anderson-Rubin, and (d) Thompson methods for calculating factor scores are reviewed. Syntax necessary to execute all four…

Goodwyn, Fara

2012-01-01

342

Development of a new and environment friendly hollow fiber-supported liquid phase microextraction using vesicular aggregate-based supramolecular solvent.  

PubMed

Hollow fiber-based liquid phase microextraction (HF-LPME) using conventional solvents is limited by their relative instability and high volatility. The use of supramolecular solvents as a liquid membrane phase could overcome these inconveniences due to their negligible vapour pressure and high viscosity. In the present study, a novel and highly flexible method was developed based on supramolecular solvents constructed of vesicles of decanoic acid, which were used for the first time as a solvent in HF-LPME. This solvent is produced from the coacervation of decanoic acid aqueous vesicles by the action of tetrabutylammonium (Bu(4)N(+)). In this work, halogenated anilines as model compounds were extracted from water samples into a supramolecular solvent impregnated in the pores and also filled inside the porous polypropylene hollow fiber membrane. The extracted anilines were separated and determined by high-performance liquid chromatography. The technique requires minimal sample preparation time and toxic organic solvent consumption, and provides a significant advantage over conventional analytical methods. The important parameters influencing the extraction efficiency were studied and optimized utilizing two different optimization methods: one variable at a time and the Box-Behnken design. Under the optimum conditions, the preconcentration factors were in the range of 74 to 203. Linearity of the method was obtained in the range of 1.0-100 ?g L(-1) with the correlation coefficients of determination (R(2)) ranging from 0.9901 to 0.9986. The limits of detection for the target anilines were 0.5-1.0 ?g L(-1). The relative standard deviations varied from 3.9% to 6.0%. The relative recoveries of the three halogenated anilines from water samples at a spiking level of 20.0 ?g L(-1) were in the range of 90.4-107.4%. PMID:22733347

Moradi, Morteza; Yamini, Yadollah; Rezaei, Fatemeh; Tahmasebi, Elham; Esrafili, Ali

2012-08-01

343

Hollow fibre-based liquid-phase microextraction technique combined with gas chromatography-mass spectrometry for the determination of pyrethroid insecticides in water samples.  

PubMed

A simple, easy-to-use, efficient and environmentally friendly method has been developed for the simultaneous analysis of nine pirethroid pesticides in water samples by the combination of hollow fibre-based liquid-phase microextraction (HF-LPME) and gas chromatography-mass spectrometry (GC/MS). For the developed method, nine pirethroid pesticides (esbiothrin, prallethrin, bifenthrin, tetramethrin, phenothrin, permethrin, cyfluthrin, cypermethrin and deltamethrin) were concentrated and well separated under optimal conditions. Several factors that influence the efficiency of HF-LPME were investigated and optimized by means of experimental design. The proposed method has good linearity in the concentration range of 10-400 ?g L(-1) with correlation coefficients between 0.995 and 0.999. Overall enrichment factors for the optimized method ranged from 139 to 255 times except for cypermethrin and deltamethrin which ranged from 35 to 128. Detection and quantitation limits of the chromatographic method were in the range of 0.002-0.012 ?g L(-1) and 0.003-0.026 ?g L(-1) respectively, with RSD values between 4.2% and 18.4%. The recoveries varied in the range of 69.4%-122.7% except for cypermethrin and deltamethrin (17.5%-64.1%) with relative standard deviations between 1.0% and 24.0% for intra and inter-day experiments at different concentrations (0.1 ?g L(-1), 0.5 ?g L(-1), 1 ?g L(-1)). The HF-LPME method optimized was applied to the analysis of three spiked real water samples with good results. PMID:23141333

San Román, I; Alonso, M L; Bartolomé, L; Alonso, R M

2012-10-15

344

Gaseous hexane biodegradation by Fusarium solani in two liquid phase packed-bed and stirred-tank bioreactors.  

PubMed

Biofiltration of hydrophobic volatile pollutants is intrinsically limited by poor transfer of the pollutants from the gaseous to the liquid biotic phase, where biodegradation occurs. This study was conducted to evaluate the potential of silicone oil for enhancing the transport and subsequent biodegradation of hexane by the fungus Fusarium solani in various bioreactor configurations. Silicone oil was first selected among various solvents for its biocompatibility, nonbiodegradability, and good partitioning properties toward hexane. In batch tests, the use of silicone oil improved hexane specific biodegradation by approximately 60%. Subsequent biodegradation experiments were conducted in stirred-tank (1.5 L) and packed-bed (2.5 L) bioreactors fed with a constant gaseous hexane load of 180 g x m(-3)(reactor) x h(-1) and operated for 12 and 40 days, respectively. In the stirred reactors, the maximum hexane elimination capacity (EC) increased from 50 g x m(-3)(reactor) x h(-1) (removal efficiency, RE of 28%) in the control not supplied with silicone oil to 120 g x m(-3)(reactor) x h(-1) in the biphasic system (67% RE). In the packed-bed bioreactors, the maximum EC ranged from 110 (50% RE) to 180 g x m(-3)(reactor) x h(-1) (> 90% RE) in the control and two-liquid-phase systems, respectively. These results represent, to the best of our knowledge, the first reported case of fungi use in a two-liquid-phase bioreactor and the highest hexane removal capacities so far reported in biofilters. PMID:16646479

Arriaga, Sonia; Muñoz, Raúl; Hernández, Sergio; Guieysse, Benoit; Revah, Sergio

2006-04-01

345

Preservation of Geometrical Integrity of Supersolidus-Liquid-Phase-Sintered SKD11 Tool Steels Prepared with Powder Injection Molding  

NASA Astrophysics Data System (ADS)

The powder injection molded SKD11 tool steels often manifest shape retention problems during supersolidus liquid phase sintering due to the difficulties in controlling the amount of liquid phase. The typical temperature range for the sintering of SKD11 is only 10 K, between 1503 and 1513 K (1230 and 1240 °C), and this narrow sintering range demands a special furnace with very uniform temperature distribution. Through the addition of carbides, in particular TiC, this problem is resolved by enlarging the liquid + ? + carbide region in the phase diagram and by impeding the grain growth with the carbides. The resulting sintering window is broadened to 40 K, between 1513 and 1553 K (1240 and 1280 °C). The relevant mechanisms on the improvement of shape retention are discussed with a focus on the effect of carbide addition on the changes in the phase diagram and the microstructure. A guideline for the selection of effective carbides is also proposed based on the experimental results and the phase diagram analyses.

Chuang, K. H.; Hwang, K. S.

2011-07-01

346

Migration of carbon nanotubes from liquid phase to vapor phase in the refrigerant-based nanofluid pool boiling.  

PubMed

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

Peng, Hao; Ding, Guoliang; Hu, Haitao

2011-01-01

347

Migration of carbon nanotubes from liquid phase to vapor phase in the refrigerant-based nanofluid pool boiling  

PubMed Central

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

2011-01-01

348

General model and segregation coefficient measurement for ultrashallow doping by excimer laser annealing  

SciTech Connect

A general model of ultrashallow doping by excimer laser annealing is derived from only one diffusion-segregation equation. In our model, the relative dopant profile after some laser shots reaches a stationary distribution, which only depends on the segregation and liquid-phase diffusion coefficients of the dopant but not on the laser-process parameters. From this result, a one-point method is proposed to experimentally determine the out-of-equilibrium segregation coefficient k. Only the relative dopant concentration at the material surface has to be measured prior to determine the k value. Experimental dopant profiles are compared to simulations generated with experimental k values.

Gillet, Jean-Numa; Degorce, Jean-Yves; Meunier, Michel [Laser Processing Laboratory, Department of Engineering Physics, Ecole Polytechnique de Montreal, C. P. 6079, succ. Centre-ville, Montreal, Quebec H3C 3A7 (Canada)

2005-05-30

349

Condensation coefficient of methanol vapor near vapor-liquid equilibrium states  

NASA Astrophysics Data System (ADS)

This paper is concerned with the nonequilibrium condensation from a vapor to a liquid phase on the plate endwall of a shock tube behind a reflected shock wave. The growth of a liquid film on the endwall is measured by an optical interferometer using a laser beam. The experiment is carefully conducted on the precisely designed apparatus, and thereby the condensation coefficient of methanol vapor is determined in a wide range of vapor-liquid conditions from near to far from equilibrium states. The result shows that the condensation coefficient increases with the increase of the ratio of number densities of vapor and saturated vapor at the interface.

Fujikawa, S.; Yano, T.; Ichijo, M.; Iwanami, K.

350

Ultrasound-assisted third-liquid phase-transfer catalyzed esterification of sodium salicylate in a continuous two-phase-flow reactor.  

PubMed

The esterification of sodium salicylate to synthesize butyl salicylate by third-liquid phase-transfer catalysis under ultrasound irradiation was investigated in a continuous two-phase-flow reactor. The reactor was designed to keep the third-liquid phase in the middle part and to have the aqueous and organic phases flowing through it in countercurrent. Using tetra-n-butylphosphonium bromide to prepare the third-liquid phase for this esterification, the product yield in the organic outlet (toluene) at 70 degrees C was 49.7% in silent condition, showing the reaction promoted simply by countercurrent mixing of the aqueous and organic phases. In the conditions of space time at 168 min, stirring at 150 rpm and ultrasound irradiation (28 kHz, 300 W), the product yield was greatly enhanced to 78.2%. As prepared, above 90% of the added catalyst existed in the third-liquid phase, and after 4-h on stream for a large excess of n-butyl bromide to sodium salicylate, the fraction of catalyst retaining in the reactor was reduced to around 80%. The distributions of catalysts between phases before and after reaction were analyzed. A kinetic model was proposed to estimate the apparent rate constants, and the feasibility for third-liquid phase-transfer catalysis assisted by ultrasound irradiation in a continuous flow reactor was demonstrated. PMID:19560391

Yang, Hung-Ming; Peng, Guan-Yi

2010-01-01

351

Preparation of CTS Coatings Containing Calcium and Phosphorus on Titanium Surface by the Cathode Liquid Phase Plasma Technology  

NASA Astrophysics Data System (ADS)

Chitosan (CTS) coatings contained calcium (Ca) and phosphorus (P) on titanium (Ti) surface are prepared by the cathode liquid phase plasma technology (CLPT), in a certain concentration electrolyte solution with selective additions of ammonium dihydrogen phosphate and calcium nitrate. It is indicated that the parameters for a stable discharge are voltage of 400 V, frequency of 100 Hz, duty cycle of 30% based on a large amount of experiment data. The morphology, structure and composition of the coated samples are studied by SEM, FTIR, XRD, XPS. The results demonstrate that the composite coatings are uniform, and some solid particles of inorganic salt containing calcium and phosphorus dispersed on the coatings. CA tests show that the samples treated by the liquid plasma became less hydrophilic. The variation of hydrophilicity on the CLPT treated titanium is attributed to the change of the function groups on the sample surface. Meanwhile, a possible formation mechanism of the composite coatings is discussed.

Ye, Wenting; Wu, Di; Pan, Xin; Chen, Yashao; Han, Yong; Song, Zhongxiao

2010-10-01

352

Capillary electrophoresis determination of nonsteroidal anti-inflammatory drugs in wastewater using hollow fiber liquid-phase microextraction.  

PubMed

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

Villar Navarro, Mercedes; Ramos Payán, María; Fernández-Torres, Rut; Bello-López, Miguel A; Callejón Mochón, Manuel; Guiráum Pérez, Alfonso

2011-08-01

353

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

PubMed

This study is focused on optimizing the treatment parameters for high concentration ammonia using gaseous oxidation in liquid phase (GOLP). The conversion of ammonia was achieved electrothermally over mono-crystalline silicon supported CoOx catalyst. The experimental results demonstrated that factors including the co-anions, pH of the solutions, air flowrate and the current showed apparent influences on the ammonia removal. The higher the Cl(-) concentration and/or current, the better the efficiency of ammonia degradation. The increase of the air flowrate would increase the ammonia removal accordingly. And it was also observed that the pH declined during the ammonia conversion, and the neutral and alkaline pH were beneficial to the ammonia removal. The preliminary cost analysis based on lab data was also provided for future reference. PMID:22049716

Cao, Li Mei; Yang, Ji; Jia, Jin Ping

2011-01-01

354

Bonding Interface Formation between Mg Alloy and Steel by Liquid-phase Bonding using the Ag Interlayer  

NASA Astrophysics Data System (ADS)

Liquid-phase bonding between a Mg alloy (AZ31) and low-carbon steel was attempted at 773 K (500 °C) using Ag as an interlayer that forms a eutectic melt with the Mg alloy at this temperature. On the AZ31 side, eutectic melting and subsequent isothermal solidification were observed, and it was confirmed that the solidification of the eutectic liquid was promoted by the diffusion of Ag into the AZ31 base metal. On the steel side, Al was transported from AZ31 during the eutectic melting and isothermal solidification. This transported Al was enriched at the steel surface and reacted with steel to form a uniform, thin Fe-Al intermetallic compound layer. After the isothermal solidification, strong bonding was achieved via the thin intermetallic compound layer between AZ31 and steel, and no Ag remained at the bonding interface. The strength of the joint was found to be higher than the yield strength of AZ31.

Koba, Masaki; Araki, Toshio; Nambu, Shoichi; Inoue, Junya; Koseki, Toshihiko

2012-02-01

355

Free-Surface Optical Scattering as an Indicator of the Shock-Induced Solid-Liquid Phase Transition in Tin  

SciTech Connect

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. A familiar manifestation of this phenomenon is the loss of signal light in VISAR measurements, which 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 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.

Stevens, G. D.; Lutz, S. S.; Marshall, B. R.; Turley, W. D.; Veeser, L. R.; Furlanetto, M. R.; Hixson, R. S.; Holtkamp, D. B.; Jensen, B. J.; Rigg, P. A.; Wilke, M. D.

2008-07-01

356

Tailoring of high-order multiple emulsions by the liquid-liquid phase separation of ternary mixtures.  

PubMed

Multiple emulsions with an "onion" topology are useful vehicles for drug delivery, biochemical assays, and templating materials. They can be assembled by ternary liquid phase separation by microfluidics, but the control over their design is limited because the mechanism for their creation is unknown. Herein we show that phase separation occurs through self-similar cycles of mass transfer, spinodal decomposition or nucleation, and coalescence into multiple layers. Mapping out the phase diagram shows a linear relationship between the diameters of concentric layers, the slope of which depends on the initial ternary composition and the molecular weight of the surfactant. These general rules quantitatively predict the number of droplet layers (multiplicity), which we used to devise self-assembly routes for polymer capsules and liposomes. Moreover, we extended the technique to the assembly of lipid-stabilized droplets with ordered internal structures. PMID:25199633

Haase, Martin F; Brujic, Jasna

2014-10-27

357

Dielectric nanosheets made by liquid-phase exfoliation in water and their use in graphene-based electronics  

NASA Astrophysics Data System (ADS)

One of the challenges associated with the development of next-generation electronics is to find alternatives to silicon oxide caused by the size-reduction constraints of the devices. The dielectric properties of two-dimensional (2D) crystals, added to their excellent chemical stability, mechanical and thermal properties, make them promising dielectrics. Here we show that liquid-phase exfoliation (LPE) in water by using low-cost commercial organic dyes as dispersant agents can efficiently produce defect-free 2D nanosheets, including mono-layers, in suspensions. We further show that these suspensions can be easily incorporated into current practical graphene-based devices. In particular, it is found that boron nitride thin films made by LPE are excellent dielectrics that are highly compatible with graphene-based electronics.

Yang, Huafeng; Withers, Freddie; Gebremedhn, Elias; Lewis, Edward; Britnell, Liam; Felten, Alexandre; Palermo, Vincenzo; Haigh, Sarah; Beljonne, David; Casiraghi, Cinzia

2014-06-01

358

Commercial-scale demonstration of the Liquid Phase Methanol (LPMEOH{trademark}) process. Technical progress report number 11, January 1--March 31, 1997  

SciTech Connect

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.

NONE

1997-06-11

359

Catalyst and reactor development for a liquid-phase Fischer-Tropsch process. Quarterly technical progress report, 1 January 1982-31 March 1982  

SciTech Connect

This report describes work on Catalyst and Reactor Development for a Liquid Phase Fischer-Tropsch Process. The program contains four major tasks: (1) Project Work Plan, (2) Slurry Catalyst Development, (3) Slurry Reactor Design Studies, and (4) Pilot Facility Design. Two modified conventional catalysts were screened in the gas phase, and the improved results gave directions for further development work. Three slurry tests were run. The first, a 15 wt % slurry of a coprecipitated catalyst, showed non-standard Schulz-Flory product distributions, with a significant increase in C/sub 9/+ hydrocarbons. The second, a 19 wt % slurry of a support catalyst, also showed large deviations from the standard Schulz-Flory product, with a high selectivity for C/sub 10/-C/sub 25/ hydrocarbons. Compared to a previous gas phase test, however, CH/sub 4/ yields were higher and the activity lower. A third slurry test of a supported cluster catalyst also showed a lower activity than in the gas phase. Oil analysis indicates that the reduction of activity observed for supported metal catalysts in the slurry compared to the gas phase may be due to poisoning by an oil component. An alternative oil will therefore be utilized for future tests. Seven supported cluster catalysts were synthesized and six were screened in the gas phase. In two cases, an increased yield of C/sub 10/+ products was observed, dependent upon the reaction conditions. Another showed a product selectivity that could be shifted between oxygenates and hydrocarbons. Gas hold-up and solids dispersion measurements in the 5'' column were completed for the 0 to 5 ..mu..m and 45 to 53 ..mu..m iron oxide/isoparaffin, and the 45 to 53 ..mu..m and 90 to 115 ..mu..m silica/isoparaffin systems. The gas hold-up results were correlated by statistical analysis.

Dyer, P. N.; Pierantozzi, R.; Brian, B. W.; Bauer, J. V.

1982-04-01

360

Commercial-scale demonstration of the Liquid Phase Methanol process. Technical progress report number 8, April 1--June 30, 1996  

SciTech Connect

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.

NONE

1996-12-31

361

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

SciTech Connect

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 of the Liquid Phase Methanol (LPMEOH) process, this work focused on the development of slurry reactor based processes. The experimental investigations, which involved bench-scale reactor studies, focused primarily on three areas: (1) One-step, slurry-phase syngas conversion to hydrocarbons or methanol/hydrocarbon mixtures using a mixture of methanol synthesis catalyst and methanol conversion catalyst in the same slurry reactor. (2) Slurry-phase conversion of syngas to mixed alcohols using various catalysts. (3) One-step, slurry-phase syngas conversion to mixed ethers using a mixture of mixed alcohols synthesis catalyst and dehydration catalyst in the same slurry reactor. The experimental results indicate that, of the three types of processes investigated, slurry phase conversion of syngas to mixed alcohols shows the most promise for further process development. Evaluations of various mixed alcohols catalysts show that a cesium-promoted Cu/ZnO/Al[sub 2]O[sub 3] methanol synthesis catalyst, developed in Air Products' laboratories, has the highest performance in terms of rate and selectivity for C[sub 2+]-alcohols. In fact, once-through conversion at industrially practical reaction conditions yielded a mixed alcohols product potentially suitable for direct gasoline blending. Moreover, an additional attractive aspect of this catalyst is its high selectivity for branched alcohols, potential precursors to iso-olefins for use in etherification.

Underwood, R.P.

1993-01-01

362

A systematic selection of the non-aqueous phase in a bacterial two liquid phase bioreactor treating alpha-pinene.  

PubMed

A systematic evaluation of the selection criteria of non-aqueous phases in two liquid phase bioreactors (TLPBs), also named two-phase partitioning bioreactors (TPPBs), was carried out using the biodegradation of alpha-pinene by Pseudomonas fluorescens NCIMB 11671 as a model process. A preliminary solvent screening was thus carried out among the most common non-aqueous phases reported in literature for volatile organic contaminants biodegradation in TLPBs: silicon oil, paraffin oil, hexadecane, diethyl sebacate, dibutyl-phtalate, FC 40, 1,1,1,3,5,5,5-heptamethyltrisiloxane (HMS), and 2,2,4,4,6,8,8-heptamethylnonane (HMN). FC 40, silicone oil, HMS, and HMN were first selected based on its biocompatibility, resistance to microbial attack, and alpha-pinene mass transport characteristics. FC 40, HMS, HMN, and silicone oil at 10% (v/v) enhanced alpha-pinene mass transport from the gas to the liquid phase by a factor of 3.8, 14.8, 11.4, and 8.6, respectively, compared to a single-phase aqueous system. FC 40 and HMN were finally compared for their ability to enhance alpha-pinene biodegradation in a mechanically agitated bioreactor. The use of FC 40 or HMN (both at 10% v/v) sustained non-steady state removal efficiencies (RE) and elimination capacities (EC) approximately 7 and 12 times higher than those achieved in the system without an organic phase, respectively. In addition, preliminary results showed that P fluorescens could uptake and mineralize alpha-pinene directly from the non aqueous phase. PMID:18322681

Muñoz, Raúl; Chambaud, Martin; Bordel, Sergio; Villaverde, Santiago

2008-05-01

363

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

SciTech Connect

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 Si etching and post-etching chemical treatment recently developed at NREL enables excellent control over the pore diameter and pore separation. Performance of black Si solar cells, including open-circuit voltage, short-circuit current density, and blue response, has benefited from these improvements. Prior to this study, our black Si solar cells were all passivated by thermal SiO2 produced in tube furnaces. Although this passivation is effective, it is not yet ideal for ultra-low-cost manufacturing. In this study, we report, for the first time, the integration of black Si with a proprietary liquid-phase deposition (LPD) passivation from Natcore Technology. The Natcore LPD forms a layer of <10-nm SiO2 on top of the black Si surface in a relatively mild chemical bath at room temperature. We demonstrate black Si solar cells with LPD SiO2 with a spectrum-weighted average reflection lower than 5%, similar to the more costly thermally grown SiO2 approach. However, LPD SiO2 provides somewhat better surface-passivation quality according to the lifetime analysis by the photo-conductivity decay measurement. Moreover, black Si solar cells with LPD SiO2 passivation exhibit higher spectral response at short wavelength compared to those passivated by thermally grown SiO2. With further optimization, the combination of aqueous black Si etching and LPD could provide a pathway for low-cost, high-efficiency crystalline Si solar cells.

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

2012-06-01

364

Liquid phase hydrodechlorination of chlorophenols at lower temperature on a novel Pd catalyst.  

PubMed

Pd catalyst supported on mesoporous silica-carbon nano-composite (Pd/MSCN) was prepared by the method of wet impregnation, and its activity for hydrodechlorination (HDC) of 2-chlorophenol, 4-chlorophenol and 2,4-dichlorophenol was evaluated at 258-313 K under ordinary hydrogen pressure by using triethylamine (Et(3)N) as a base additive. XRD analysis indicates that Pd/MSCN catalyst possesses the ordered mesostructure. Meanwhile, the results from TEM and H(2) chemisorption analysis indicate the high dispersion of Pd on MSCN with Pd nanoparticles whose average size is 3.2 nm. For the first time, the high activity of nano-size Pd on MSCN for HDC of chlorophenols was observed at 258 K. In addition, it was found that the inhibition effect of Et(3)N on HDC existed obviously, and can be efficiently reduced by stepwise addition of Et(3)N. The correlations of the dielectric constants of base and the polarity of solvent to the activity of Pd/MSCN for HDC of chlorophenols were obtained. PMID:21239107

Jin, Zhonghao; Yu, Chao; Wang, Xingyi; Wan, Ying; Li, Dao; Lu, Guanzhong

2011-02-28

365

Biosorption of model pollutants in liquid phase on raw and modified rice husks  

NASA Astrophysics Data System (ADS)

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.

Toniazzo, L.; Fierro, V.; Braghiroli, F.; Amaral, G.; Celzard, A.

2013-03-01

366

Effect of oil concentration and residence time on the biodegradation of ?-pinene vapours in two-liquid phase suspended-growth bioreactors.  

PubMed

Recently, research on the use of binary aqueous-organic liquid phase systems for the treatment of polluted air has significantly increased. This paper reports the removal of ?-pinene from a waste air stream in a continuous stirred tank bioreactor (CSTB), using either a single-liquid aqueous phase or a mixed aqueous-organic liquid phase. The influence of gas flow rate, load and pollutant concentration was evaluated as well as the effect of the organic to aqueous phase ratio. Continuous experiments were carried out at different inlet ?-pinene concentrations, ranging between 0.03 and 25.1 g m?³ and at four different flow rates, corresponding to residence times (RTs) of 120 s, 60 s, 36 s and 26 s. The maximum elimination capacities (ECs) reached in the CSTB were 382 g m?³ h?¹ (without silicone oil) and 608 g m?³ h?¹ (with 5%v/v silicone oil), corresponding to a 1.6-fold improvement using an aqueous-organic liquid phase. During shock-loads experiments, the performance and stability of the CSTB were enhanced with 5% silicone oil, quickly recovering almost 100% removal efficiency (RE), when pre-shock conditions were restored. The addition of silicone oil acted as a buffer for high ?-pinene loads, showing a more stable behaviour in the case of two-liquid-phase systems. PMID:21807039

Montes, María; Veiga, María C; Kennes, Christian

2012-02-20

367

Surface Phenomena and Their Role in the Processes of Liquid-Phase Sintering and Impregnation of Porous Bodies by Liquid Metals  

Microsoft Academic Search

The role of surface phenomena in the processes of liquid-phase sintering of porous materials and impregnation of porous bodies with liquid metals is considered on the basis of fundamentals of physical chemistry of metals and non-metals. The technological applications of capillar phenomena in soldering materials of different nature are considered.

Valentin N. Eremenko

2002-01-01

368

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)

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.

Anspaugh, B. E.; Downing, R. G.; Miyahira, T. F.; Weiss, R. S.

1981-01-01

369

PHYSICAL REVIEW B 83, 205107 (2011) Possible realization of the exciton Bose liquid phase in a hard-core boson model with ring-only  

E-print Network

PHYSICAL REVIEW B 83, 205107 (2011) Possible realization of the exciton Bose liquid phase in a hardÃ?1 plaquettes, with a goal of realizing a novel exciton Bose liquid (EBL) phase first proposed by Paramekanti et al. [Phys. Rev. B 66, 054526 (2002)]. We construct Jastrow-type variational wave functions

Jensen, Grant J.

370

Regioselective biooxidation of (+)-valencene by recombinant E. coli expressing CYP109B1 from Bacillus subtilis in a two-liquid-phase system  

PubMed Central

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

Girhard, Marco; Machida, Kazuhiro; Itoh, Masashi; Schmid, Rolf D; Arisawa, Akira; Urlacher, Vlada B

2009-01-01

371

High temperature furnace for liquid phase epitaxy of silicon carbide in microgravity 1 1 Based on paper IAF96-J5.08 presented at the 47th International Astronautical Congress, October 7–11, 1996, Beijing, China  

Microsoft Academic Search

The high temperature furnace for Liquid Phase Epitaxy (LPE) was developed by Swedish Space Corporation. It was developed for a Silicon Carbide liquid phase epitaxy microgravity experiment performed by Linköping University, Sweden. The LPE is capable of processing materials up to 1900°C in ultra clean atmosphere or vacuum in accordance with requirements for semiconductor crystal growth. The LPE has the

Christian Lockowandt; Rositza Yakimova; Mikael Syväjärvi; Erik Janzén

1999-01-01

372

Effects of phosphorus deficiency on rumen microbial activity associated with the solid and liquid phases of a fermentor  

E-print Network

and supplemented buffers were interchanged to determine the effects of P repletion and depletion. The proportion) are fed. Since low P intake is often shown to reduce the amount of salivary P entering the rumen not always shown clear-cut results because of large variations in the responses of the hosts in terms of food

Paris-Sud XI, Université de

373

Progress and developments in the field of materials for transient liquid phase bonding and active soldering processes  

Microsoft Academic Search

In the last decade, microsystem engineering has rapidly developed. Nowadays microsystems have a very broad scope of applications, which range from electronics and aerospace to chemistry, optics, biology and medicine. Within this framework, the joining technique plays a crucial role. Therefore the development of new concepts for joining hybrid microstructures is one of the main tasks within the collaborative research

E. Lugscheider; S. Ferrara; H. Janssen; A. Reimann; B. Wildpanner

2004-01-01

374

New mesoporous perovskite ZnTiO 3 and its excellent catalytic activity in liquid phase organic transformations  

Microsoft Academic Search

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

Nabanita Pal; Manidipa Paul; Asim Bhaumik

2011-01-01

375

Generation of surface nanostructures on nickel by liquid-phase laser ablation and their surface-enhanced Raman scattering activity  

SciTech Connect

Surface nanostructuring of nickel by ablation with 350-ps Nd:YAG laser pulses in ethanol has been studied experimentally. The morphology of the nanostructured surface has been examined using a field emission scanning electron microscope. The average lateral size of the surface nanostructures is 30 - 50 nm. The nanostructured surface has been coated with gold using a chemical deposition procedure. The gold-coated substrate has shown surface-enhanced Raman scattering with an enhancement factor of 10{sup 8}. Potential applications of such nanostructured targets are discussed. (nanostructures)

Barmina, E V [Wave Research Center, A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Levi, Zh [ITODYS, Universite Paris (France); Lau Truong, C; Bozon-Verdyura, F; Simakin, Aleksandr V; Shafeev, Georgii A

2010-06-23

376

Final environmental assessment for the Liquid Phase Methanol (LPMEOH{trademark}) Project  

SciTech Connect

The proposed project is to demonstrate on a commercial scale the production of methanol from coal-derived synthesis gas using the LPMEOH{trademark} process. The methanol produced during this demonstration will be used as a chemical feedstock (on-site) and/or as an alternative fuel in stationary and transportation applications (off-site). In addition, the production of dimethyl ether (DME) as a mixed co-product with methanol may be demonstrated for a six month period under the proposed project pending the results of laboratory/pilot-scale research on scale-up. The DME would be used as fuel in on-site boilers. The proposed LPMEOH facility would occupy approximately 0.6 acres of the 3,890-acre Eastman Chemical facility in Kingsport, TN. The effects of the proposed project include changes in air emissions, wastewater discharge, cooling water discharge, liquid waste quantities, transportation activities, socioeconomic effects, and quantity of solids for disposal. No substantive negative impacts or environmental concerns were identified.

NONE

1995-06-01

377

Preparation of Few-Layer Bismuth Selenide by Liquid-Phase-Exfoliation and Its Optical Absorption Properties  

PubMed Central

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

Sun, Liping; Lin, Zhiqin; Peng, Jian; Weng, Jian; Huang, Yizhong; Luo, Zhengqian

2014-01-01

378

Preparation of few-layer bismuth selenide by liquid-phase-exfoliation and its optical absorption properties.  

PubMed

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

Sun, Liping; Lin, Zhiqin; Peng, Jian; Weng, Jian; Huang, Yizhong; Luo, Zhengqian

2014-01-01

379

Revisiting dynamics near a liquid-liquid phase transition in Si and Ga: The fragile-to-strong transition  

SciTech Connect

Using molecular dynamics simulations we analyze the dynamics of two atomic liquids that display a liquid-liquid phase transition (LLPT): Si described by the Stillinger-Weber potential and Ga as modeled by the modified embedded-atom model. In particular, our objective is to investigate the extent to which the presence of a dip in the self-intermediate scattering function is a manifestation of an excess of vibrational states at low frequencies and may be associated with a fragile-to-strong transition (FTST) across the LLPT, as suggested recently. Our results suggest a somewhat different picture. First, in the case of Ga we observe the appearance of an excess of vibrational states at low frequencies, even in the absence of the appearance of a dip in the self-intermediate scattering function across the LLPT. Second, studying the behavior of the shear viscosities traversing the LLPTs we find that both substances are fragile in character above and below their respective LLPT temperatures. Instead of a FTST in an absolute sense these findings are more in line with a view in which the LLPTs are accompanied by a transition from a more fragile to a less fragile liquid. Furthermore, we do not find this transition to correlate with the presence of a dip in the intermediate scattering function.

Cajahuaringa, Samuel; Koning, Maurice de, E-mail: dekoning@ifi.unicamp.br; Antonelli, Alex, E-mail: aantone@ifi.unicamp.br [Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, UNICAMP, 13083-859 Campinas, São Paulo (Brazil)] [Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, UNICAMP, 13083-859 Campinas, São Paulo (Brazil)

2013-12-14

380

Characterization of the Microstructure of GaP Films Grown on {111} Si by Liquid Phase Epitaxy.  

PubMed

The development of a cost-effective Si based platform on which III-V's can be grown is of great interest. This work investigates the morphology of gallium phosphide (GaP) films grown on {111} silicon (Si) substrates by means of liquid phase epitaxy in a tin (Sn) - based solvent bath. Two types of single-crystal {111} Si substrates were used; the first type was oriented exactly along the ?111? surface (no-miscut) and the second was miscut by 4°. The growth rate of the GaP films was found to be markedly different for the two types of substrates; the GaP films on the miscut Si substrate grew ?4 times faster than those on the no-miscut substrate. The GaP films grew epitaxially on both types of substrates, but contained Si and Sn as inclusions. In the case of the no-miscut substrate, a number of large Sn particles were incorporated at the GaP/Si interface. As a result, these interfacial Sn particles affected the strain state of the GaP films dramatically, which, in turn, manifested itself in the form of a duplex microstructure that consists of strained and strain-free regions. PMID:25300064

Huang, Susan R; Lu, Xuesong; Barnett, Allen; Opila, Robert L; Mogili, Vishnu; Tanner, David A; Nakahara, Shohei

2014-11-12

381

An Experimental Study of Transient Liquid Phase Bonding of the Ternary Ag-Au-Cu System Using Differential Scanning Calorimetry  

NASA Astrophysics Data System (ADS)

An experimental approach using differential scanning calorimetry (DSC) has been applied to quantify the solid/liquid interface kinetics during the isothermal solidification stage of transient liquid phase (TLP) bonding in an Ag-Au-Cu ternary alloy solid/liquid diffusion couple. Eutectic Ag-Au-Cu foil interlayers were coupled with pure Ag base metal to study the effects of two solutes on interface motion. Experimental effects involving baseline shift and primary solidification contribute to a systematic underestimation of the fraction of liquid remaining. A temperature program has been used to quantify and correct these effects. The experimental results show a linear relationship between the interface position and the square root of the isothermal hold time. The shifting tie line composition at the interface has been shown to affect the DSC results; however, the impact on the calculated interface kinetics has been shown to be minimal in this case. This work has increased the knowledge of isothermal solidification in ternary alloy systems and developed accurate experimental methods to characterize these processes, which is valuable for designing TLP bonding schedules.

Kuntz, M. L.; Panton, B.; Wasiur-Rahman, S.; Zhou, Y.; Corbin, S. F.

2013-08-01

382

Preparation of Few-Layer Bismuth Selenide by Liquid-Phase-Exfoliation and Its Optical Absorption Properties  

NASA Astrophysics Data System (ADS)

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.

Sun, Liping; Lin, Zhiqin; Peng, Jian; Weng, Jian; Huang, Yizhong; Luo, Zhengqian

2014-04-01

383

Reduced-Temperature Transient-Liquid-Phase Bonding of AluminaUsing a Ag-Cu-Based Brazing Alloy  

SciTech Connect

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.

Hong, Sung Moo; Glaeser, Andreas M.

2005-12-19

384

Liquid-phase-deposited silicon oxide film as a mask for single-sided texturing of monocrystalline Si wafers.  

PubMed

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

Lin, Tao; Jiang, Kun; Zhou, Bo-Xuan; Xu, Su-Fan; Cai, Wen-Bin

2014-01-22

385

Saddle-like deformation in a dielectric elastomer actuator embedded with liquid-phase gallium-indium electrodes  

NASA Astrophysics Data System (ADS)

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.

Wissman, J.; Finkenauer, L.; Deseri, L.; Majidi, C.

2014-10-01

386

Carrier-mediated liquid phase microextraction coupled with high performance liquid chromatography for determination of illicit drugs in human urine.  

PubMed

A new method was developed for the analysis of illicit drugs in human urine by coupling carrier-mediated liquid phase microextraction (LPME) to high performance liquid chromatography (HPLC). By adding an appropriate carrier in organic phase, simultaneous extraction and enrichment of hydrophilic (morphine and ephedrine) and hydrophobic (pethidine) drugs were achieved. Effects of the types of organic solvents and carriers, the carrier concentration in the organic phase, the HCl concentration in the acceptor solution, the stirring rate, and the extraction time on the enrichment factor of analytes were investigated. Under the optimal experimental conditions, high enrichment factors (202-515) were obtained. The linear detection ranges were 0.1-10mgL(-1) for the studied drugs. The limits of detection (LOD) at signal-to-noise ratio of 3 were 0.05mgL(-1) for both morphine and ephedrine, and 0.02mgL(-1) for pethidine. This method was successfully applied to analysis of ephedrine in real urine specimens, revealing that the determination of illicit drugs in urine was feasible. PMID:18573383

Zhang, Zhaohui; Zhang, Chenggong; Su, Xiaoli; Ma, Ming; Chen, Bo; Yao, Shouzhuo

2008-07-28

387

Iron-histidine resonance raman band of deoxyheme proteins: effects of anharmonic coupling and glass-liquid phase transition  

PubMed Central

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

Bitler, A; Stavrov, SS

1999-01-01

388

Determination at low ppm levels of dithiocarbamate residues in foodstuff by vapour phase-liquid phase microextraction-infrared spectroscopy.  

PubMed

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

Gonzálvez, Ana; Garrigues, Salvador; Armenta, Sergio; de la Guardia, Miguel

2011-03-01

389

Interface Development in Cu-Based Structures Transient Liquid Phase (TLP) Bonded with Thin Al Foil Intermediate Layers  

NASA Astrophysics Data System (ADS)

Proper bonding and assembly techniques are essential for fabrication of functional metal-based microdevices. Transient liquid phase (TLP) bonding is a promising technique for making enclosed metallic microchannel devices. In this paper, we report results of TLP bonding of Cu-based structures at temperatures between 823 K and 883 K (550 °C and 610 °C) with thin elemental Al foils as intermediate boding layers. In situ X-ray diffraction was utilized to examine the structure of Cu/Al interface in real time, resulting in a proposed sequence of structural evolution of the Cu/Al/Cu TLP bonding interface region. Three different types of bonding interface structures, the " ? 1 structure," the "eutectoid structure" ("E structure"), and the "E/ ? 1/E structure," were observed through electron microscopy, and related to the proposed sequence of interfacial structural evolution. Tensile fracture tests were conducted on TLP-bonded Cu/Al/Cu coupon assemblies. Hardness of the various phases within the bonding interface region was probed with instrumented nanoindentation. Results of mechanical testing were correlated to the structure of the bonding interface region. The present results provide an understanding of the structural evolution within the Cu/Al/Cu TLP bonding interface region, and offer guidance to future bonding of Cu-based microsystems.

Chen, Ke; Meng, Wen Jin; Eastman, J. A.

2014-08-01

390

Analysis of oestrogenic compounds in dairy products by hollow-fibre liquid-phase microextraction coupled to liquid chromatography.  

PubMed

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

Socas-Rodríguez, Bárbara; Asensio-Ramos, María; Hernández-Borges, Javier; Rodríguez-Delgado, Miguel Ángel

2014-04-15

391

Liquid phase Fischer-Tropsch (II) demonstration in the LaPorte Alternative Fuels Development Unit. Volume 1/2, Main Report. Final report  

SciTech Connect

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.

Bhatt, B.L.

1995-09-01

392

Determination of phenolic compounds in environmental water samples after solid-phase extraction with ?-cyclodextrin-bonded silica particles coupled with a novel liquid-phase microextraction followed by gas chromatography-mass spectrometry.  

PubMed

A novel approach for the sample pre-treatment and determination of eight phenolic compounds in environmental water samples has been developed by hyphenating solid-phase extraction (SPE) and liquid-phase microextraction (LPME) techniques based on solid organic drop combined with gas chromatography-mass spectrometry detection (GC-MS). After pre-concentration and purification of the sample through column containing 60 mg of ?-cyclodextrin-bonded silica particles as stationary phase, under the optimum conditions, LPME technique has been performed on the eluent solution. Under the selected conditions, limit of detection (LOD) of 0.002-0.04 ?g/L (S/N=3), limit of quantification (LOQ) of 0.007-0.15 ?g/L (S/N=10), pre-concentration factor of 752-3135 and linearity range of 0.01-25 ?g/L have been obtained. A reasonable repeatability (RSD?9.5%, n=5) with satisfactory coefficient of determination has been obtained between 0.9981 and 0.9997. The relative recoveries of the waste, sea, river and well water samples were higher than 79%. PMID:22102622

Faraji, Hakim; Husain, Syed W; Helalizadeh, Masoumeh

2012-01-01

393

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

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

Yang, Xian; Wang, Bo-Chu; Zhang, Xue; Yang, Shui-Ping; Li, Wei; Tang, Qian; Singh, Gurinder K

2011-01-25

394

Analytical study of the liquid phase transient behavior of a high temperature heat pipe. M.S. Thesis  

NASA Technical Reports Server (NTRS)

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.

Roche, Gregory Lawrence

1988-01-01

395

Spin dynamics and disorder effects in the S =1/2 kagome Heisenberg spin-liquid phase of kapellasite  

NASA Astrophysics Data System (ADS)

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.

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

396

Order-parameter-aided temperature-accelerated sampling for the exploration of crystal polymorphism and solid-liquid phase transitions.  

PubMed

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

Yu, Tang-Qing; Chen, Pei-Yang; Chen, Ming; Samanta, Amit; Vanden-Eijnden, Eric; Tuckerman, Mark

2014-06-01

397

Ion-pair hollow-fiber liquid-phase microextraction of the quaternary ammonium surfactant dicocodimethylammonium chloride.  

PubMed

A two-phase hollow-fiber (HF) liquid-phase microextraction (LPME) method was developed for determination of a quaternary ammonium compound surfactant, dicocodimethylammonium chloride, in aqueous samples. The porous HF was fixed on a metal rod support and was impregnated with approximately 6.6 microL of organic extractant, which was immobilized in the HF pores. Surfactant extraction was facilitated by addition of carboxylic acid to the sample forming neutral ion pairs with the quaternary ammonium compound. After extraction, the analyte was transferred from the organic extractant in the fiber pores by dissolving the 1-octanol into 100 microL methanol. The methanol extract was analyzed by liquid chromatography-mass spectrometry. The method was optimized (with optimized parameters in brackets) with regard to type of organic extractant (1-octanol), fiber length (2 cm), choice and concentration of anionic carrier (600 microg L(-1) octanoate), procedure of transfer to methanol (15-min sonication), sample volume (250 mL), extraction time (17 h), pH (10), and ionic strength (50 mM carbonate). Aspects influencing repeatability in LPME of (quaternary ammonium) surfactants are discussed. The enrichment factor achieved in 250-mL carbonate buffer was around 400. Due to matrix effects, the enrichment factors achieved when industrial process water was analyzed were 120 or about 30% of that in carbonate buffer. Detection limits of 0.3 microg L(-1) in carbonate buffer and 0.9 microg L(-1) in industrial process water were obtained. If the studied compound is seen as a model substance representing quaternary dialkylated dimethylated ammonium surfactants in general, the developed method may be applied to other quaternary ammonium surfactants. PMID:19050857

Hultgren, Sofie; Larsson, Niklas; Nilsson, Bo F; Jönsson, Jan Ake

2009-02-01

398

Structural, electrical and phototransient characteristics of liquid phase epitaxial GaP based heterojunction for photodiode application  

NASA Astrophysics Data System (ADS)

Heterojunction of GaP/p-Si device was successfully grown by liquid phase epitaxy. A structural characteristic of the heterojunction device was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). X-ray peak broadening analysis was used to evaluate the crystallite size by using the Williamson-Hall (W-H) analysis. The capacitance-voltage (C-V) and current-voltage (I-V) characteristics were measured in the temperature range 300-400 K under dark condition. The dependence of C-2 on V is found to be almost linear which indicates that the type of the heterojunction is abrupt. The main junction parameters such as built-in potential (Vb), the donor carrier concentration (ND) and the width of the depletion region (W) were extracted from C-V characteristics and studied as a function of temperature. The I-V characteristics of the heterojunction device exhibit moderate rectifying behavior which can be attributed to the formation of heterojunction interface. At lower voltages, the forward current of the device is found to obey the intrinsic thermally generated charge carriers. At relatively higher voltages, the current mechanism of the heterojunction is controlled by a space charge limited conduction mechanism device. The main parameters of the heterojunction device such as series resistance (RS), shunt resistance (Rsh), the ideality factor (n) and the barrier height (?b) were determined from I-V characteristics. Photocurrent of the heterojunction device increases with increasing power intensity and the transient photocurrent results indicate that the photocurrent can be explained by continuous distribution of traps.

Ashery, A.; Farag, A. A. M.; Zeama, Mostafa

2014-02-01

399

Degradation of Liquid-Phase Shear Horizontal Surface Acoustic Wave Sensor Owing to Lack of Energy Concentration of Surface and a Compensation Method  

NASA Astrophysics Data System (ADS)

In this paper we describe liquid-phase two-channel shear horizontal surface acoustic wave (SH-SAW) delay-line sensor devices on 36° Y-X LiTaO3 substrates. One delay line has a metallized propagation area and the other has an unmetallized propagation area. The permittivity and conductivity of the liquids can be calculated from the velocity changes and attenuation changes of the SH-SAWs in the two delay-lines. However, in the case of the low-permittivity liquids, the SH-SAWs in the delay line with an unmetallized propagation area can be degraded owing to the lack of SH-SAW energy concentration of the surface. Thus the obtained permittivity and conductivity of the liquids were slightly different from the exact values. In this paper, the drawback of the liquid-phase SH-SAW sensors is described, and in order to overcome this drawback, a compensation method is presented.

Kogai, Takashi; Yatsuda, Hiromi; Shiokawa, Showko

2008-05-01

400

Electrical properties of p + \\/ n + In 0.53 Ga 0.47 As tunnel diodes grown by liquid phase epitaxy  

Microsoft Academic Search

p+\\/n+ In0.53Ga0.47As tunnel diodes were prepared by liquid phase epitaxy and their electrical properties were characterized. These devices exhibit large forward conductances (2.59×103 ??1 cm?2), high peak current densities (793 A\\/cm2) and large peak to valley current ratios (16.2). These devices offer great promise as intercell ohmic contacts (IOCs) for InP-based, onolithic multijunction solar cells.

C. C. Shen; P. T. Chang; K. Y. Choi

1993-01-01

401

Electrical properties of p + \\/ n + InGaAsP tunnel diodes with a bandgap of 0.95 eV grown by liquid phase epitaxy  

Microsoft Academic Search

p+\\/n+ InGaAsP tunnel diodes with a bandgap of 0.95 eV were fabricated by liquid phase epitaxy and their electrical properties were characterized. Forward conductances of 500 F-1 cm-2, peak current densities of 28.5 A\\/cm2 and peak to valley current ratios of 14.3 were obtained at room temperature. These devices were incorporated successfully as Intercell Ohmic Connections (IOCs) for an InP-based,

C. C. Shen; P. T. Chang

1994-01-01

402

Electrical properties of p +\\/ n + In0.53Ga0.47As tunnel diodes grown by liquid phase epitaxy  

Microsoft Academic Search

p +\\/ n + In0.53Ga0.47As tunnel diodes were prepared by liquid phase epitaxy and their electrical properties were characterized. These devices exhibit large forward conductances (2.59×103 Omega-1 cm-2), high peak current densities (793 A\\/cm2) and large peak to valley current ratios (16.2). These devices offer great promise as intercell ohmic contacts (IOCs) for InP-based, onolithic multijunction solar cells.

C. C. Shen; P. T. Chang; K. Y. Choi

1993-01-01

403

Morphology of crystalline Nylon610 membranes prepared by the immersion-precipitation process: competition between crystallization and liquid–liquid phase separation  

Microsoft Academic Search

Nylon-610 membranes were prepared at 25°C by direct immersion of various dope solutions into either formic acid\\/water or 1-octanol bath. Depending on the dope and bath conditions, the precipitated membranes demonstrated characteristics derived from crystallization and\\/or liquid–liquid phase separation during the precipitation process. As a good dope solution was immersed in a harsh bath, e.g., water, precipitation occurred initiated by

Tai-Horng Young; Dar-Jong Lin; Jy-Jye Gau; Wen-Yuan Chuang; Liao-Ping Cheng

1999-01-01

404

Effect of catalyst concentration and simulation of precipitation processes on liquid-phase catalytic oxidation of p-xylene to terephthalic acid  

Microsoft Academic Search

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

A. Cincotti; R. Orrù; A. Broi; G. Cao

1997-01-01

405

Liquid-phase hydrogenation of benzene to cyclohexene catalyzed by Ru\\/SiO 2 in the presence of water–organic mixtures  

Microsoft Academic Search

The liquid-phase hydrogenation of benzene to cyclohexene was studied using a Ru\\/SiO2 catalyst prepared by reduction of ruthenium(III) chloride impregnated in a hydrophilic non-porous silica. In a biphasic water\\/benzene system at 423 K and 5 MPa of hydrogen pressure, a 14% cyclohexene yield was obtained at 60% benzene conversion. Increased cyclohexene yields and selectivities were observed in the presence of

Estevam V. Spinacé; Jorge M. Vaz

2003-01-01

406

Kinetics of liquid phase synthesis of tert-amyl ethyl ether from tert-amyl alcohol and ethanol over Amberlyst 16  

Microsoft Academic Search

This work concerns catalyst screening for the synthesis of tert-amyl ethyl ether (TAEE) from a liquid-phase reaction between tert-amyl alcohol (TAA) and ethanol (EtOH). Various commercial catalysts, i.e., Amberlyst 15, Amberlyst 16, Amberlyst 36, Amberlyst 131, ?-zeolite with Si\\/Al=13.5 and 40, and Dowex 50WX8, were tested by performing the reaction in a semi-batch reactor operated at temperature of 353K and

O. Boonthamtirawuti; W. Kiatkittipong; A. Arpornwichanop; P. Praserthdam; S. Assabumrungrat

2009-01-01

407

Temperature-Controlled Catalyst Recycling: New Protocols Based upon Temperature-Dependent Solubilities of Fluorous Compounds and Solid\\/Liquid Phase Separations  

Microsoft Academic Search

The absolute solubilities of fluorous compounds can be tailored by varying the lengths of the (CF2)\\u000a n?1CF3 (Rfn\\u000a )\\u000a segments. Many such compounds exhibit immense solubility increases in organic solvents or neat liquid reactants\\u000a upon heating. Suitably designed fluorous catalysts can therefore be employed under homogeneous conditions\\u000a at elevated temperatures, and recovered by solid\\/liquid phase separation at lower temperatures. Expensive

John A. Gladysz; Verona Tesevic

408

N/P InP homojunction solar cells with an In0.53Ga0.47As contacting layer grown by liquid phase epitaxy  

NASA Technical Reports Server (NTRS)

N/P InP homojunction solar cells with an In sub 0.53 Ga sub 0.47 As contacting layer were fabricated by liquid phase epitaxy (LPE). Electron-Beam-Induced-Current (EBIC) measurements were performed on several selected samples. It was found that the background doping level in the base region sometimes results in a deep junction, which greatly affects the cell performance.

Shen, C. C.; Choi, K. Y.

1989-01-01

409

Thermally stable ion-exchange resins as catalysts for the liquid-phase dehydration of 1-pentanol to di- n-pentyl ether (DNPE)  

Microsoft Academic Search

Conversion, selectivity, yield, and kinetics of the liquid-phase dehydration of 1-pentanol to di-n-pentyl ether (DNPE) were determined at 403–463 K on a recently developed sulfonated resin, Amberlyst 70, which is thermally stable up to 473 K. The behavior of Amberlyst 70 was compared with that of Nafion resin NR50, an H-Beta zeolite, and styrene-divinylbenzene resins stable up to 423 K

Roger Bringué; Montserrat Iborra; Javier Tejero; José Felipe Izquierdo; Fidel Cunill; Carles Fité; Victor J. Cruz

2006-01-01

410

Surface tension of the 60%Bi–24%Cu–16%Sn alloy and the critical temperature of the immiscible liquid phase separation  

Microsoft Academic Search

In order to control the core-shell structure of bimetallic lead-free solder balls, the surface tension and the critical temperature for the phase separation of two immiscible liquid phases are required. In this study, the temperature dependence of the surface tension of the 60%Bi–24%Cu–16%Sn alloy was measured using the constrained drop method. The temperature dependence of the surface tension was changed

Soonki Min; Joonho Lee

2008-01-01

411

Improving electrochemical properties of liquid phase deposited TiO 2 thin films by doping sodium dodecylsulfonate and its application as bioelectrocatalytic sensor for hydrogen peroxide  

Microsoft Academic Search

Electroactive TiO2 films were prepared by liquid-phase deposition (LPD) in the presence of sodium dodecylsulfonate. The doping of dodecylsulfonate (DS) converted the TiO2 film from a structure of globular nanoparticles to a structure of nano-flakes, which directly influenced the electrochemical behavior of the film. The DS-doped TiO2 film yields an enhanced reduction peak in the cyclic voltammograms, being attributed to

Guodong Jiang; Heqing Tang; Lihua Zhu; Jingdong Zhang; Bin Lu

2009-01-01

412

Deep reactive ion etching (Deep-RIE) process for fabrication of ordered structural metal oxide thin films by the liquid phase infiltration method  

Microsoft Academic Search

Deep reactive ion etching (Deep-RIE) process was established for fabrication of highly nano-ordered metal oxide thin films such as TiO2, ZrO2, SnO2 etc, by the liquid phase infiltration (LPI) method. Electron beam lithography (EBL) technique and Deep-RIE were adapted to fabricate the Si wafer coated with a positive resist ZEP520A. Etching gas of SF6 and C4F8 was used for Deep-RIE

Minoru Mizuhata; Takuya Miyake; Yuki Nomoto; Shigehito Deki

2008-01-01

413

Selective engineering in O-alkylation of m-cresol with benzyl chloride using liquid–liquid–liquid phase transfer catalysis  

Microsoft Academic Search

Selective O-alkylation or etherification of phenolic substances is attractive to make pharmaceuticals and fine chemicals. Liquid–liquid phase transfer catalysis (L–L PTC) is used to make such ethers but it always leads to byproduct formation and wastage of catalyst. On the contrary, liquid–liquid–liquid (L–L–L) PTC is an excellent strategy for waste reduction and improving profitability, in which a catalyst-rich middle (or

Ganapati D. Yadav; Omprakash V. Badure

2008-01-01

414

Phase equilibria for binary n-alkanenitrile- n-alkane mixtures. III. Vapour-liquid phase equilibria for propanenitrile with C 5?C 8 n-alkanes  

Microsoft Academic Search

Vapour-liquid phase equilibria at 313.15 K for the four mixtures of propanenitrile with n-pentane, n-hexane, n-heptane and n-octane have been determined by the measurement of the total vapour pressure in a static apparatus. All mixtures display azeotropy, with the alkane mole fraction of the azeotrope moving from 0.938 in the C5 mixture to 0.239 for the C8 mixture. The excess

Ian A. McLure; Jose-Luis Arriaga-Colina; David A. Armitage

1997-01-01

415

Transient liquid-phase bonding of ferritic oxide dispersion strengthened superalloy MA957 using a conventional nickel braze and a novel iron-base foil  

Microsoft Academic Search

It has been shown that an iron foil based on the Fe-B-Si system is a suitable material for use as a high-temperature interlayer for transient liquid-phase (TLP) bonding of ferritic oxide dispersion strengthened alloys. TLP bonding produced ferritic joints, free from intermetallic precipitates and identical in composition to that of the parent metal. In contrast, however, TLP bonding using the

T. I. Khan; E. R. Wallach

1995-01-01

416

Photoinduced Crystal-to-Liquid Phase Transitions of Azobenzene Derivatives and Their Application in Photolithography Processes through a Solid-Liquid Patterning.  

PubMed

The direct and reversible transformation of matter between the solid and liquid phases by light at constant temperature is of great interest because of its potential applications in various manufacturing settings. We report a simple molecular design strategy for the phase transitions: azobenzenes having para-dialkoxy groups with a methyl group at the meta-position. The photolithography processes were demonstrated using the azobenzene as a photoresist in a single process combining development and etching of a copper substrate. PMID:25216186

Norikane, Yasuo; Uchida, Emi; Tanaka, Satoko; Fujiwara, Kyoko; Koyama, Emiko; Azumi, Reiko; Akiyama, Haruhisa; Kihara, Hideyuki; Yoshida, Masaru

2014-10-01

417

Liquid phase microextraction with in situ derivatization for measurement of bisphenol A in river water sample by gas chromatography–mass spectrometry  

Microsoft Academic Search

A new method that involves liquid phase microextraction (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 river water samples. The LPME conditions, such as the type of extraction solvent and the extraction time, are investigated. Then, the extract is directly injected into GC–MS. The detection

Migaku Kawaguchi; Rie Ito; Naoyuki Endo; Noriya Okanouchi; Norihiro Sakui; Koichi Saito; Hiroyuki Nakazawa

2006-01-01

418

Liquid-phase microextraction combined with gas chromatography mass spectrometry for rapid determination of nicotine in one-drop of nightshades vegetables and commercial food products  

Microsoft Academic Search

A simple, rapid and sensitive ultrasound-assisted hollow fibre liquid-phase microextraction (UA-HF-LPME) is evaluated for the determination of nicotine in one-drop of nightshade vegetables and some of the commercial food products. The optimum extraction of nicotine was obtained by using 1.5?L as an extracting solvent in 1.0cm of hollow fibre for 10min extraction time with addition of salt. The calculated calibration

Kamlesh Shrivas; Devesh Kumar Patel

2010-01-01

419

INTERNATIONAL CONFERENCE ON SEMICONDUCTOR INJECTION LASERS SELCO-87: Two-stage liquid phase epitaxy for fabrication of buried InGaAsP/InP heterostructures  

NASA Astrophysics Data System (ADS)

The technology of growth of buried heterojunction lasers emitting at 1.3 ?m and some of their physical properties are described. Mesa stripes 8-?m wide were formed on heteroepitaxial wafers grown by liquid phase epitaxy at 630°C. They were buried by a second process at a lower temperature (590°C). The threshold current was about 100 mA and the temperature sensitivity was characterized by a parameter amounting to about 60 K. Single-mode lasing was observed occasionally.

Procházková, O.; Novotný, J.; Šrobár, F.

1988-11-01

420

A novel light trapping concept for liquid phase crystallized poly-Si thin-film solar cells on periodically nanoimprinted glass substrates  

NASA Astrophysics Data System (ADS)

Large grained polycrystalline silicon (poly-Si) absorbers were realized by electron beam induced liquid phase crystallization on 2 ?m periodically patterned glass substrates and processed into a-Si:H/poly-Si heterojunction thin-film solar cells. The substrates were structured by nanoimprint lithography using a UV curable hybrid polymer sol-gel resist, resulting in a glassy high-temperature stable micro-structured surface. Structural analysis yielded high quality poly-Si material with grain sizes up to several hundred micrometers. An increase of absorption and an enhancement of the external quantum efficiency in the NIR as a consequence of light trapping due to the micro-structured poly-Si/substrate interface were observed. Up to now, only moderate solar cell parameters, a maximum open-circuit voltage of 413 mV and a short-circuit current density of 8 mA cm-2, were measured being significantly lower to what can be achieved with liquid phase crystallized poly-Si thin-film solar cells on planar glass substrates indicating that the substrate texture has impact on the electrical material quality. By reduction of the SiC interlayer thickness at the micro-structured poly- Si/substrate interface defect-related parasitic absorption was considerably minimized. This encourages the implementation of nanoimprinted tailored substrate textures for light trapping in liquid phase crystallized poly-Si thinfilm solar cells.

Preidel, V.; Amkreutz, D.; Sontheimer, T.; Back, F.; Rudigier-Voigt, E.; Rech, B.; Becker, C.

2013-09-01