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Sample records for volatile liquid phase

  1. Electric-field triggered controlled release of bioactive volatiles from imine-based liquid crystalline phases.

    Science.gov (United States)

    Herrmann, Andreas; Giuseppone, Nicolas; Lehn, Jean-Marie

    2009-01-01

    Application of an electric field to liquid crystalline film forming imines with negative dielectric anisotropy, such as N-(4-methoxybenzylidene)-4-butylaniline (MBBA, 1), results in the expulsion of compounds that do not participate in the formation of the liquid crystalline phase. Furthermore, amines and aromatic aldehydes undergo component exchange with the imine by generating constitutional dynamic libraries. The strength of the electric field and the duration of its application to the liquid crystalline film influence the release rate of the expelled compounds and, at the same time, modulate the equilibration of the dynamic libraries. The controlled release of volatile organic molecules with different chemical functionalities from the film was quantified by dynamic headspace analysis. In all cases, higher headspace concentrations were detected in the presence of an electric field. These results point to the possibility of using imine-based liquid crystalline films to build devices for the controlled release of a broad variety of bioactive volatiles as a direct response to an external electric signal.

  2. Phase change events of volatile liquid perfluorocarbon contrast agents produce unique acoustic signatures

    Science.gov (United States)

    Sheeran, Paul S.; Matsunaga, Terry O.; Dayton, Paul A.

    2014-01-01

    Phase-change contrast agents (PCCAs) provide a dynamic platform to approach problems in medical ultrasound (US). Upon US-mediated activation, the liquid core vaporizes and expands to produce a gas bubble ideal for US imaging and therapy. In this study, we demonstrate through high-speed video microscopy and US interrogation that PCCAs composed of highly volatile perfluorocarbons (PFCs) exhibit unique acoustic behavior that can be detected and differentiated from standard microbubble contrast agents. Experimental results show that when activated with short pulses PCCAs will over-expand and undergo unforced radial oscillation while settling to a final bubble diameter. The size-dependent oscillation phenomenon generates a unique acoustic signal that can be passively detected in both time and frequency domain using confocal piston transducers with an ‘activate high’ (8 MHz, 2 cycles), ‘listen low’ (1 MHz) scheme. Results show that the magnitude of the acoustic ‘signature’ increases as PFC boiling point decreases. By using a band-limited spectral processing technique, the droplet signals can be isolated from controls and used to build experimental relationships between concentration and vaporization pressure. The techniques shown here may be useful for physical studies as well as development of droplet-specific imaging techniques.

  3. Simultaneous flame ionization and absorbance detection of volatile and nonvolatile compounds by reversed-phase liquid chromatography with a water mobile phase.

    Science.gov (United States)

    Bruckner, C A; Ecker, S T; Synovec, R E

    1997-09-01

    A flame ionization detector (FID) is used to detect volatile organic compounds that have been separated by water-only reversed-phase liquid chromatography (WRP-LC). The mobile phase is 100% water at room temperature, without use of organic solvent modifiers. An interface between the LC and detector is presented, whereby a helium stream samples the vapor of volatile components from individual drops of the LC eluent, and the vapor-enriched gas stream is sent to the FID. The design of the drop headspace cell is simple because the water-only nature of the LC separation obviates the need to do any organic solvent removal prior to gas phase detection. Despite the absence of organic modifier, hydrophobic compounds can be separated in a reasonable time due to the low phase volume ratio of the WRP-LC columns. The drop headspace interface easily handles LC flows of 1 mL/min, and, in fact, compound detection limits are improved at faster liquid flow rates. The transfer efficiency of the headspace interface was estimated at 10% for toluene in water at 1 mL/min but varies depending on the volatility of each analyte. The detection system is linear over more than 5 orders of 1-butanol concentration in water and is able to detect sub-ppb amounts of o-xylene and other aromatic compounds in water. In order to analyze volatile and nonvolatile analytes simultaneously, the FID is coupled in series to a WRP-LC system with UV absorbance detection. WRP-LC improves UV absorbance detection limits because the absence of organic modifier allows the detector to be operated in the short-wavelength UV region, where analytes generally have significantly larger molar absorptivities. The selectivity the headspace interface provides for flame ionization detection of volatiles is demonstrated with a separation of 1-butanol, 1,1,2-trichloroethane (TCE), and chlorobenzene in a mixture of benzoic acid in water. Despite coelution of butanol and TCE with the benzoate anion, the nonvolatile benzoate anion

  4. Synthesis and toxicity evaluation of hydrophobic ionic liquids for volatile organic compounds biodegradation in a two-phase partitioning bioreactor

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez Castillo, Alfredo Santiago [Ecole Nationale Supérieure de Chimie de Rennes, CNRS, UMR 6226, 11 Allée de Beaulieu, CS 50837, 35708 Rennes Cedex 7 (France); Université européenne de Bretagne (France); Guihéneuf, Solène, E-mail: solene.guiheneuf@wanadoo.fr [Université européenne de Bretagne, Université de Rennes 1, Sciences Chimiques de Rennes, UMR, CNRS 6226, Groupe Ingénierie Chimique & Molécules Pour le Vivant (ICMV), Bât. 10A, Campus de Beaulieu, Avenue du Général Leclerc, CS 74205, 35042 Rennes cedex (France); Le Guével, Rémy [Plate-forme ImPACcell Structure Fédérative de Recherche BIOSIT Université de Rennes 1, Bat. 8, Campus de Villejean, 2 Avenue du Pr. Leon Bernard, CS 34317, 35043 Rennes Cedex (France); Biard, Pierre-François [Ecole Nationale Supérieure de Chimie de Rennes, CNRS, UMR 6226, 11 Allée de Beaulieu, CS 50837, 35708 Rennes Cedex 7 (France); Université européenne de Bretagne (France); and others

    2016-04-15

    Highlights: • Description of a VOC depollution system suitable with industrial processes, TPPB. • Novel association of TPPB and hydrophobic ionic liquids. • Synthesis of several hydrophobic ionic liquids designed to fit desired properties. • Toxicity evaluation of these ILs towards cells, animals and bacteria. - Abstract: Synthesis of several hydrophobic ionic liquids (ILs), which might be selected as good candidates for degradation of hydrophobic volatile organic compounds in a two-phase partitioning bioreactor (TPPB), were carried out. Several bioassays were also realized, such as toxicity evaluation on activated sludge and zebrafish, cytotoxicity, fluoride release in aqueous phase and biodegradability in order to verify their possible effects in case of discharge in the aquatic environment and/or human contact during industrial manipulation. The synthesized compounds consist of alkylimidazoliums, functionalized imidazoliums, isoqinoliniums, triazoliums, sulfoniums, pyrrolidiniums and morpholiniums and various counter-ions such as: PF{sub 6}{sup −}, NTf{sub 2}{sup −} and NfO{sup −}. Toxicity evaluation on activated sludge of each compound (5% v/v of IL) was assessed by using a glucose uptake inhibition test. Toxicity against zebrafish and cytotoxicity were evaluated by the ImPACCell platform of Rennes (France). Fluoride release in water was estimated by regular measurements using ion chromatography equipment. IL biodegradability was determined by measuring BOD{sub 28} of aqueous samples (compound concentration,1 mM). All ILs tested were not biodegradable; while some of them were toxic toward activated sludge. Isoquinolinium ILs were toxic to human cancerous cell lines. Nevertheless no toxicity was found against zebrafish Danio rerio. Only one IL released fluoride after long-time agitation.

  5. Analysis of beer volatiles by polymeric imidazolium-solid phase microextraction coatings: Synthesis and characterization of polymeric imidazolium ionic liquids.

    Science.gov (United States)

    González-Álvarez, Jaime; Blanco-Gomis, Domingo; Arias-Abrodo, Pilar; Pello-Palma, Jairo; Ríos-Lombardía, Nicolás; Busto, Eduardo; Gotor-Fernández, Vicente; Gutiérrez-Álvarez, María Dolores

    2013-08-30

    Two polymeric ionic liquids, 3-(but-3″-en-1″-yl)-1-[2'-hydroxycyclohexyl]-1H-imidazol-3-ium bis(trifluoromethanesulfonyl)imide (IL-1) and 1-(2'-hydroxycyclohexyl)-3-(4″-vinylbenzyl)-1H-imidazol-3-ium bis(trifluoromethylsulfonyl)imide (IL-2), have been synthesized by a free radical polymerization reaction and used as coatings for solid-phase microextraction (SPME). These new fibers exhibit good film stability, high thermal stability (270-290°C) and long lifetimes, and are used for the extraction of volatile compounds in lemon beer using gas chromatography separation and flame ionization detection. The scanning electron micrographs of the fiber surface revealed a polymeric ionic liquid (PIL) film, which is distributed homogeneously on the fiber. The developed PIL fiber showed good linearity between 50 and 2000μg/L with regression coefficients in the range of 0.996-0.999. The relative standard deviations (RSD) obtained in the peak area were found to vary between 1% and 12%, which assured that adequate repeatability was achieved. The spiked recoveries for three beer samples ranged from 78.4% to 123.6%. Experimental design has been employed in the optimization of extraction factors and robustness assessment. The polymeric IL-1 butenyl fiber showed a greater efficiency compared to the PDMS-DVB (65μm) and CAR-PDMS (75μm) for the extraction of all of the analytes studied.

  6. Synthesis and toxicity evaluation of hydrophobic ionic liquids for volatile organic compounds biodegradation in a two-phase partitioning bioreactor.

    Science.gov (United States)

    Rodriguez Castillo, Alfredo Santiago; Guihéneuf, Solène; Le Guével, Rémy; Biard, Pierre-François; Paquin, Ludovic; Amrane, Abdeltif; Couvert, Annabelle

    2016-04-15

    Synthesis of several hydrophobic ionic liquids (ILs), which might be selected as good candidates for degradation of hydrophobic volatile organic compounds in a two-phase partitioning bioreactor (TPPB), were carried out. Several bioassays were also realized, such as toxicity evaluation on activated sludge and zebrafish, cytotoxicity, fluoride release in aqueous phase and biodegradability in order to verify their possible effects in case of discharge in the aquatic environment and/or human contact during industrial manipulation. The synthesized compounds consist of alkylimidazoliums, functionalized imidazoliums, isoqinoliniums, triazoliums, sulfoniums, pyrrolidiniums and morpholiniums and various counter-ions such as: PF6(-), NTf2(-) and NfO(-). Toxicity evaluation on activated sludge of each compound (5% v/v of IL) was assessed by using a glucose uptake inhibition test. Toxicity against zebrafish and cytotoxicity were evaluated by the ImPACCell platform of Rennes (France). Fluoride release in water was estimated by regular measurements using ion chromatography equipment. IL biodegradability was determined by measuring BOD28 of aqueous samples (compound concentration,1mM). All ILs tested were not biodegradable; while some of them were toxic toward activated sludge. Isoquinolinium ILs were toxic to human cancerous cell lines. Nevertheless no toxicity was found against zebrafish Danio rerio. Only one IL released fluoride after long-time agitation. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Polymeric ionic liquid coatings versus commercial solid-phase microextraction coatings for the determination of volatile compounds in cheeses.

    Science.gov (United States)

    Trujillo-Rodríguez, María J; Yu, Honglian; Cole, William T S; Ho, Tien D; Pino, Verónica; Anderson, Jared L; Afonso, Ana M

    2014-04-01

    The extraction performance of four polymeric ionic liquid (PIL)-based solid-phase microextraction (SPME) coatings has been studied and compared to that of commercial SPME coatings for the extraction of 16 volatile compounds in cheeses. The analytes include 2 free fatty acids, 2 aldehydes, 2 ketones and 10 phenols and were determined by headspace (HS)-SPME coupled to gas chromatography (GC) with flame-ionization detection (FID). The PIL-based coatings produced by UV co-polymerization were more efficient than PIL-based coatings produced by thermal AIBN polymerization. Partition coefficients of analytes between the sample and the coating (Kfs) were estimated for all PIL-based coatings and the commercial SPME fiber showing the best performance among the commercial fibers tested: carboxen-polydimethylsyloxane (CAR-PDMS). For the PIL-based fibers, the highest K(fs) value (1.96 ± 0.03) was obtained for eugenol. The normalized calibration slope, which takes into account the SPME coating thickness, was also used as a simpler approximate tool to compare the nature of the coating within the determinations, with results entirely comparable to those obtained with estimated K(fs) values. The PIL-based materials obtained by UV co-polymerization containing the 1-vinyl-3-hexylimidazolium chloride IL monomer and 1,12-di(3-vinylimiazolium)dodecane dibromide IL crosslinker exhibited the best performance in the extraction of the select analytes from cheeses. Despite a coating thickness of only 7 µm, this copolymeric sorbent coating was capable of quantitating analytes in HS-SPME in a 30 to 2000 µg L(-1) concentration range, with correlation coefficient (R) values higher than 0.9938, inter-day precision values (as relative standard deviation in %) varying from 6.1 to 20%, and detection limits down to 1.6 µg L(-1).

  8. Use of volatile organic solvents in headspace liquid-phase microextraction by direct cooling of the organic drop using a simple cooling capsule.

    Science.gov (United States)

    Ghiasvand, Ali Reza; Yazdankhah, Fatemeh; Hajipour, Somayeh

    2016-08-01

    A low-cost and simple cooling-assisted headspace liquid-phase microextraction device for the extraction and determination of 2,6,6-trimethyl-1,3 cyclohexadiene-1-carboxaldehyde (safranal) in Saffron samples, using volatile organic solvents, was fabricated and evaluated. The main part of the cooling-assisted headspace liquid-phase microextraction system was a cooling capsule, with a Teflon microcup to hold the extracting organic solvent, which is able to directly cool down the extraction phase while the sample matrix is simultaneously heated. Different experimental factors such as type of organic extraction solvent, sample temperature, extraction solvent temperature, and extraction time were optimized. The optimal conditions were obtained as: extraction solvent, methanol (10 μL); extraction temperature, 60°C; extraction solvent temperature, 0°C; and extraction time, 20 min. Good linearity of the calibration curve (R(2) = 0.995) was obtained in the concentration range of 0.01-50.0 μg/mL. The limit of detection was 0.001 μg/mL. The relative standard deviation for 1.0 μg/mL of safranal was 10.7% (n = 6). The proposed cooling-assisted headspace liquid-phase microextraction device was coupled (off-line) to high-performance liquid chromatography and used for the determination of safranal in Saffron samples. Reasonable agreement was observed between the results of the cooling-assisted headspace liquid-phase microextraction high-performance liquid chromatography method and those obtained by a validated ultrasound-assisted solvent extraction procedure.

  9. Determination of volatile compounds in cider apple juices using a covalently bonded ionic liquid coating as the stationary phase in gas chromatography.

    Science.gov (United States)

    Pello-Palma, Jairo; González-Álvarez, Jaime; Gutiérrez-Álvarez, María Dolores; Dapena de la Fuente, Enrique; Mangas-Alonso, Juan José; Méndez-Sánchez, Daniel; Gotor-Fernández, Vicente; Arias-Abrodo, Pilar

    2017-04-01

    A chromatographic method for the separation of volatile compounds in Asturian cider apple juices has been developed. For this separation purpose, a monocationic imidazolium-based ionic liquid bearing a reactive terminal iodine atom was synthesized by a quaternization-anion exchange chemical sequence. Next, the gas chromatography (GC) stationary phase was prepared by covalently linking the imidazolium monolith to the reactive silanol groups of the inner capillary wall at 70 °C. This coated GC column exhibited good thermal stability (290 °C), as well as good efficiency (2000 plates/m) in the separation of volatile compounds from Asturian apple cider juices, and was characterized using the Abraham solvation parameter model. The intra-day and inter-day precision of the chromatographic method was evaluated, obtaining relative standard deviations from 3.7 to 12.9% and from 7.4 to 18.0%, respectively. Furthermore, recoveries from 82.5 to 122% were achieved. Graphical Abstract Covalent bonding of an ionic liquid to inner column wall led to a great improvement of the separation efficiencies of stationary phases in gas chromatography.

  10. Enhanced resolution of Mentha piperita volatile fraction using a novel medium-polarity ionic liquid gas chromatography stationary phase.

    Science.gov (United States)

    Ragonese, Carla; Sciarrone, Danilo; Grasso, Elisa; Dugo, Paola; Mondello, Luigi

    2016-02-01

    The evaluation of a novel medium-polarity ionic-liquid-based gas chromatography column, SLB-IL60, towards the analysis of a complex essential oil, namely, a peppermint essential oil sample, is reported. The SLB-IL60 30 m column was subjected to bleeding measurements, by means of conventional gas chromatography with mass spectrometry. The SLB-IL60 column was then evaluated in the analysis of pure standard compounds, chosen as typical constituents of peppermint essential oil. Resolution and peak symmetry (expressed as tailing factors at 10% of peak height) were measured and the results were compared to those obtained on the most widely used columns in such an application, namely a medium-polarity [100% poly(ethyleneglycol)] stationary phase, and an apolar 5% diphenyl/95% dimethyl siloxane. The final part of the evaluation was dedicated to the gas chromatography with mass spectrometry analysis of a peppermint essential oil sample and again the data were compared to those obtained on the 100% poly(ethyleneglycol) and the 5% diphenyl/95% dimethyl siloxane phase. Linear retention indices were determined for all the identified components on the ionic liquid capillary. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. LIGHT NONAQUEOUS PHASE LIQUIDS

    Science.gov (United States)

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

  12. Modeling of liquid phases

    CERN Document Server

    Soustelle, Michel

    2015-01-01

    This book is part of a set of books which offers advanced students successive characterization tool phases, the study of all types of phase (liquid, gas and solid, pure or multi-component), process engineering, chemical and electrochemical equilibria, and the properties of surfaces and phases of small sizes. Macroscopic and microscopic models are in turn covered with a constant correlation between the two scales. Particular attention has been given to the rigor of mathematical developments. This second volume in the set is devoted to the study of liquid phases.

  13. Vapor condensation onto a non-volatile liquid drop

    Energy Technology Data Exchange (ETDEWEB)

    Inci, Levent; Bowles, Richard K., E-mail: richard.bowles@usask.ca [Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5C9 (Canada)

    2013-12-07

    Molecular dynamics simulations of miscible and partially miscible binary Lennard–Jones mixtures are used to study the dynamics and thermodynamics of vapor condensation onto a non-volatile liquid drop in the canonical ensemble. When the system volume is large, the driving force for condensation is low and only a submonolayer of the solvent is adsorbed onto the liquid drop. A small degree of mixing of the solvent phase into the core of the particles occurs for the miscible system. At smaller volumes, complete film formation is observed and the dynamics of film growth are dominated by cluster-cluster coalescence. Mixing into the core of the droplet is also observed for partially miscible systems below an onset volume suggesting the presence of a solubility transition. We also develop a non-volatile liquid drop model, based on the capillarity approximations, that exhibits a solubility transition between small and large drops for partially miscible mixtures and has a hysteresis loop similar to the one observed in the deliquescence of small soluble salt particles. The properties of the model are compared to our simulation results and the model is used to study the formulation of classical nucleation theory for systems with low free energy barriers.

  14. Molecular Beam Studies of Volatile Liquids and Fuel Surrogates Using Liquid Microjets

    Science.gov (United States)

    2014-12-18

    Molecular Beam Studies of Volatile Liquids and Fuel Surrogates Using Liquid Microjets Gilbert Nathanson, Department of Chemistry University of...alter the dynamics of evaporation from the commercial jet fuel Jet A. These results are outlined below. Exploring Fuels in Vacuum using Liquid ...hydrocarbon liquids inside a vacuum chamber. These jets, narrower than a human hair, are typically 10 – 40 µm in diameter. Their small surface area and

  15. Turbulence effects on volatilization rates of liquids and solutes

    Science.gov (United States)

    Lee, J.-F.; Chao, H.-P.; Chiou, C.T.; Manes, M.

    2004-01-01

    Volatilization rates of neat liquids (benzene, toluene, fluorobenzene, bromobenzene, ethylbenzene, m-xylene, o-xylene, o-dichlorobenzene, and 1-methylnaphthalene) and of solutes (phenol, m-cresol, benzene, toluene, ethylbenzene, o-xylene, and ethylene dibromide) from dilute water solutions have been measured in the laboratory over a wide range of air speeds and water-stirring rates. The overall transfer coefficients (KL) for individual solutes are independent of whether they are in single- or multi-solute solutions. The gas-film transfer coefficients (kG) for solutes in the two-film model, which have hitherto been estimated by extrapolation from reference coefficients, can now be determined directly from the volatilization rates of neatliquids through anew algorithm. The associated liquid-film transfer coefficients (KL) can then be obtained from measured KL and kG values and solute Henry law constants (H). This approach provides a novel means for checking the precision of any kL and kG estimation methods for ultimate prediction of KL. The improved kG estimation enables accurate K L predictions for low-volatility (i.e., low-H) solutes where K L and kGH are essentially equal. In addition, the prediction of KL values for high-volatility (i.e., high-H) solutes, where KL ??? kL, is also improved by using appropriate reference kL values.

  16. Non-Equilibrium Gibbs' Criterion for Completely Wetting Volatile Liquids

    CERN Document Server

    Tsoumpas, Yannis; Galvagno, Mariano; Rednikov, Alexey; Ottevaere, Heidi; Thiele, Uwe; Colinet, Pierre

    2014-01-01

    During the spreading of a liquid over a solid substrate, the contact line can stay pinned at sharp edges until the contact angle exceeds a critical value. At (or sufficiently near) equilibrium, this is known as Gibbs' criterion. Here, we show both experimentally and theoretically that for completely wetting volatile liquids there also exists a dynamically-produced critical angle for depinning, which increases with the evaporation rate. This suggests that one may introduce a simple modification of the Gibbs' criterion for (de)pinning, that accounts for the non-equilibrium effect of evaporation.

  17. Quantum Phase Liquids-Fermionic Superfluid without Phase Coherence

    OpenAIRE

    Wu, Ya-Jie; Zhou, Jiang; Kou, Su-Peng

    2014-01-01

    We investigate the two dimensional generalized attractive Hubbard model in a bipartite lattice, and and a "quantum phase liquid" phase, in which the fermions are paired but don't have phase coherence at zero temperature, in analogy to quantum spin liquid phase. Then, two types of topological quantum phase liquids with a small external magnetic field-Z2 quantum phase liquids and chiral quantum phase liquids-are discussed.

  18. Liquid-liquid phase transition in Stillinger-Weber silicon

    Energy Technology Data Exchange (ETDEWEB)

    Beaucage, Philippe; Mousseau, Normand [Departement de Physique and Regroupement Quebecois sur les Materiaux de Pointe, Universite de Montreal, CP 6128, Succursale Centre-ville, Montreal, QC, H3C 3J7 (Canada)

    2005-04-20

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

  19. Fast and simple screening for the simultaneous analysis of seven metabolites derived from five volatile organic compounds in human urine using on-line solid-phase extraction coupled with liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Chiang, Wen-Chieh; Chen, Chao-Yu; Lee, Ting-Chen; Lee, Hui-Ling; Lin, Yu-Wen

    2015-01-01

    Recently, the International Agency for Research on cancer classified outdoor air pollution and particulate matter from outdoor air pollution as carcinogenic to humans (IARC Group 1), based on sufficient evidence of carcinogenicity in humans and experimental animals and strong mechanistic evidence. In particular, a wide variety of volatile organic compounds (VOCs) are volatized or released into the atmosphere and can become ubiquitous, as they originate from many different natural and anthropogenic sources, such as paints, pesticides, vehicle exhausts, cooking fumes, and tobacco smoke. Humans may be exposed to VOCs through inhalation, ingestion, or dermal contact, which may increase the risk of leukemia, birth defects, neurocognitive impairment, and cancer. Therefore, the focus of this study was the development of a simple, effective and rapid sample preparation method for the simultaneous determination of seven metabolites (6 mercaptic acids+t,t-muconic acid) derived from five VOCs (acrylamide, 1,3-butadiene, acrylonitrile, benzene, and xylene) in human urine by using automated on-line solid-phase extraction (SPE) coupled with liquid chromatography-electrospray tandem mass spectrometry (LC-MS/MS). An aliquot of each diluted urinary sample was directly injected into an autosampler through a trap column to reduce contamination, and then the retained target compounds were eluted by back-flush mode into an analytical column for separation. Negative electrospray ionization tandem mass spectrometry was utilized for quantification. The coefficients of correlation (r(2)) for the calibration curves were greater than 0.995. Reproducibility was assessed by the precision and accuracy of intra-day and inter-day precision, which showed results for coefficient of variation (CV) that were low 0.9 to 6.6% and 3.7 to 8.5%, respectively, and results for recovery that ranged from 90.8 to 108.9% and 92.1 to 107.7%, respectively. The limits of detection (LOD) and limits of

  20. Analysis of volatiles of malt whisky by solid-phase microextraction and stir bar sorptive extraction.

    Science.gov (United States)

    Demyttenaere, Jan C R; Martínez, Jorge I Sánchez; Verhé, Roland; Sandra, Pat; De Kimpe, Norbert

    2003-01-24

    Blended Scotch whisky was analysed by solid-phase microextraction (SPME) and stir bar sorptive extraction (SBSE) to study the composition of the volatiles. For SPME analysis, three different fibres were compared, poly(dimethylsiloxane) (PDMS) (100 microm). poly(acrylate) (PA) (85 microm) and divinylbenzene-Carboxen on poly(dimethylsiloxane) (DVB-CAR-(PDMS) (50/30 microm). It was found that the PDMS and DVB-CAR-PDMS fibres showed a higher enrichment capacity than PA as well as a better reproducibility. The influence of sampling time, temperature and salt addition on the enrichment of volatiles as well as the difference between liquid and headspace SPME were studied. An optimum SPME method was developed. Finally a more recent sample preparation technique, namely SBSE was evaluated to extract whisky volatiles.

  1. APPARATUS FOR LIQUID PHASE EXTRACTION

    Science.gov (United States)

    Hicks, T.R.; Lehman, H.R.; Rubin, B.

    1958-09-16

    operation is described. It comprises a tubular colunm having upper and lower enlarged terminal portions, and a constricted central section containing fluid dispersal packing. Pulsing means are coupled to the upper portion of the column. The inlet for the less dense phase is located above the inlet for the denser phase and both are positioned so that liquids enter the constricted packingfilled central section. The apparatos also includes an interfacing level control, and means fer sensing the level of the interface actuate apparatus for controlling the rate of flow of input or discharge. The outlet for the less dense phase is located in the upper packing free portion of the colunm and that of the denser phase in the lower portion.

  2. Characteristics of a non-volatile liquid propellant in liquid-fed ablative pulsed plasma thrusters

    Science.gov (United States)

    Ling, William Yeong Liang; Schönherr, Tony; Koizumi, Hiroyuki

    2017-02-01

    In the past several decades, the use of electric propulsion in spacecraft has experienced tremendous growth. With the increasing adoption of small satellites in the kilogram range, suitable propulsion systems will be necessary in the near future. Pulsed plasma thrusters (PPTs) were the first form of electric propulsion to be deployed in orbit, and are highly suitable for small satellites due to their inherent simplicity. However, their lifetime is limited by disadvantages such as carbon deposition leading to thruster failure, and complicated feeding systems required due to the conventional use of solid propellants (usually polytetrafluoroethylene (PTFE)). A promising alternative to solid propellants has recently emerged in the form of non-volatile liquids that are stable in vacuum. This study presents a broad comparison of the non-volatile liquid perfluoropolyether (PFPE) and solid PTFE as propellants on a PPT with a common design base. We show that liquid PFPE can be successfully used as a propellant, and exhibits similar plasma discharge properties to conventional solid PTFE, but with a mass bit that is an order of magnitude higher for an identical ablation area. We also demonstrate that the liquid PFPE propellant has exceptional resistance to carbon deposition, completely negating one of the major causes of thruster failure, while solid PTFE exhibited considerable carbon build-up. Energy dispersive X-ray spectroscopy was used to examine the elemental compositions of the surface deposition on the electrodes and the ablation area of the propellant (or PFPE encapsulator). The results show that based on its physical characteristics and behavior, non-volatile liquid PFPE is an extremely promising propellant for use in PPTs, with an extensive scope available for future research and development.

  3. Tequila volatile characterization and ethyl ester determination by solid phase microextraction gas chromatography/mass spectrometry analysis.

    Science.gov (United States)

    Vallejo-Cordoba, Belinda; González-Córdova, Aarón Fernando; del Carmen Estrada-Montoya, María

    2004-09-08

    Solid phase microextraction (SPME) and gas chromatography were used for tequila volatile characterization and ethyl ester quantitation. Several factors determined the differences in tequila volatile profiles obtained by the SPME technique, namely, sampling mode, fiber coating, and fiber exposure time. Each of these factors determined the most suitable conditions for the analysis of volatile profiles in tequila. Volatile extraction consisted of placing 40 mL of tequila in a sealed vial kept at 40 degrees C. A poly(dimethylsiloxane) fiber was immersed in the liquid for 60 min and desorbed for 5 min into the gas chromatograph. The identified volatiles by mass spectrometry were mainly alcohols, esters, and ketones. The calibration curves for ethyl hexanoate, octanoate, and decanoate followed linear relationships with highly significant (p tequila samples. Quantitative differences in ethyl esters were found for the four most commonly known tequila types: silver, gold, aged, and extra-aged.

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

    Science.gov (United States)

    Koury, Albert M.; Parcher, Jon F.

    1979-01-01

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

  5. Simple and specific colorimetric detection of Staphylococcus using its volatile 2-[3-acetoxy-4,4,14-trimethylandrost-8-en-17-yl] propanoic acid in the liquid phase and head space of cultures.

    Science.gov (United States)

    Saranya, Raju; Aarthi, Raju; Sankaran, Krishnan

    2015-05-01

    Spread of drug-resistant Staphylococcus spp. into communities pose danger demanding effective non-invasive and non-destructive tools for its early detection and surveillance. Characteristic volatile organic compounds (VOCs) produced by bacteria offer new diagnostic targets and novel approaches not exploited so far in infectious disease diagnostics. Our search for such characteristic VOC for Staphylococcus spp. led to the depiction of 2-[3-acetoxy-4,4,14-trimethylandrost-8-en-17-yl] propanoic acid (ATMAP), a moderately volatile compound detected both in the culture and headspace when the organism was grown in tryptone soya broth (TSB) medium. A simple and inexpensive colorimetric method (colour change from yellow to orange) using methyl red as the pH indicator provided an absolutely specific way for identifying Staphylococcus spp., The assay performed in liquid cultures (7-h growth in TSB) as well as in the headspace of plate cultures (grown for 10 h on TSA) was optimised in a 96-well plate and 12-well plate formats, respectively, employing a set of positive and negative strains. Only Staphylococcus spp. showed the distinct colour change from yellow to orange due to the production of the above VOC while in the case of other organisms, the reagent remained yellow. The method validated using known clinical and environmental strains (56 including Staphylococcus, Proteus, Pseudomonas, Klebsiella, Bacillus, Shigella and Escherichia coli) was found to be highly efficient showing 100% specificity and sensitivity. Such simple methods of bacterial pathogen identification are expected to form the next generation tools for the control of infectious diseases through early detection and surveillance of causative agents.

  6. Zinc and volatile element loss during planetary magma ocean phases

    Science.gov (United States)

    Dhaliwal, Jasmeet K.; Day, James M. D.; Moynier, Frédéric

    2016-10-01

    Zinc is a moderately volatile element and a key tracer of volatile depletion on planetary bodies due to lack of significant isotopic fractionation under high-temperature processes. Terrestrial basalts have δ66Zn values similar to some chondrites (+ 0.15 to 0.3‰ where [{66Zn/64Znsample/66Zn/64ZnJMC-Lyon-1} × 1000]) and elevated Zn concentrations (100 ppm). Lunar mare basalts yield a mean δ66Zn value of +1.4 ± 0.5‰ and have low Zn concentrations (~2 ppm). Late-stage lunar magmatic products, such as ferroan anorthosite, Mg-suite and Alkali suite rocks exhibit heavier δ66Zn values (+3 to +6‰). The heavy δ66Zn lunar signature is thought to reflect evaporative loss and fractionation of zinc, either during a giant impact or in a magma ocean phase.We explore conditions of volatile element loss within a lunar magma ocean (LMO) using models of Zn isotopic fractionation that are widely applicable to planetary magma oceans. For the Moon, our objective was to identify conditions that would yield a δ66Zn signature of ~ +1.4‰ within the mantle, assuming a terrestrial mantle zinc starting composition.We examine two cases of zinc evaporative fractionation: (1) lunar surface zinc fractionation that was completed prior to LMO crystallization and (2) lunar surface zinc fractionation that was concurrent with LMO crystallization. The first case resulted in a homogeneous lunar mantle and the second case yielded a stratified lunar mantle, with the greatest zinc isotopic enrichment in late-stage crystallization products. This latter case reproduces the distribution of zinc isotope compositions in lunar materials quite well.We find that hydrodynamic escape was not a dominant process in losing Zn, but that erosion of a nascent lunar atmosphere, or separation of condensates into a proto-lunar crust are possible. While lunar volatile depletion is still possible as a consequence of the giant impact, this process cannot reproduce the variable δ66Zn found in the Moon. Outgassing

  7. Liquidity, Volatility and Stock Price Adjustment: Evidence from Seasoned Equity Offerings in an Emerging Market

    OpenAIRE

    Chia-Cheng Ho; Chin-Chuan Lee; Chien-Ting Lin; C. Edward Wang

    2005-01-01

    Using data from the Taiwanese stock market, an emerging market, this paper documents positive changes in liquidity and volatility around seasoned equity offerings (SEOs). These findings are consistent with the uncertain signal hypothesis that investors with diverse views on the information content of SEOs are likely to induce larger trading activity and subsequent higher stock return volatility. We also provide direct evidence that changes in liquidity is positively associated with stock pric...

  8. Liquid phase chromatography on microchips.

    Science.gov (United States)

    Kutter, Jörg P

    2012-01-20

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

  9. Liquid phase chromatography on microchips

    DEFF Research Database (Denmark)

    Kutter, Jörg Peter

    2012-01-01

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

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

    Science.gov (United States)

    Kneafsey, Timothy J.; Hunt, James R.

    2004-02-01

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

  11. Phase-field simulation of liquid phase migration in the WC-Co system during liquid phase sintering

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Kaiming; Zhang, Lijun; Du, Yong [Central South Univ., Changsha (China). State Key Lab. of Powder Metallurgy; Schwarze, Christian; Steinbach, Ingo [Bochum Univ. (Germany). Interdisciplinary Centre for Advanced Materials Simulation

    2016-04-15

    Liquid phase sintering is a process for forming high performance, multiple-phase components from powders. The process includes very complex interactions between various mass transportation phenomena, among which the liquid phase migration represents an important one in the aspect of forming a gradient structure in cemented carbide. In the present work, phase-field simulation of the liquid phase migration phenomenon during liquid phase sintering is performed in the WC-Co based cemented carbide. The simulation results are analyzed and compared with the experimentally determined key factors of microstructural evolution, such as contiguity and liquid phase migration rate. The diffusion-controlled solution-precipitation mechanism of the liquid phase migration process in the cemented carbide system is confirmed from the current simulation result, which provides deeper understanding of the microstructural evolution during the liquid phase migration process. These simulations can offer guidance in preventing the liquid phase migration process during liquid phase sintering of cellular cemented carbide.

  12. Application of ionic liquid in liquid phase microextraction technology.

    Science.gov (United States)

    Han, Dandan; Tang, Baokun; Lee, Yu Ri; Row, Kyung Ho

    2012-11-01

    Ionic liquids (ILs) are novel nonmolecular solvents. Their unique properties, such as high thermal stability, tunable viscosity, negligible vapor pressure, nonflammability, and good solubility for inorganic and organic compounds, make them excellent candidates as extraction media for a range of microextraction techniques. Many physical properties of ILs can be varied, and the structural design can be tuned to impart the desired functionality and enhance the analyte extraction selectivity, efficiency, and sensitivity. This paper provides an overview of the applications of ILs in liquid phase microextraction technology, such as single-drop microextraction, hollow fiber based liquid phase microextraction, and dispersive liquid-liquid microextraction. The sensitivity, linear calibration range, and detection limits for a range of target analytes in the methods were analyzed to determine the advantages of ILs in liquid phase microextraction. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Does C60 have a liquid phase?

    NARCIS (Netherlands)

    Hagen, M.H.J.; Meijer, E.J.; Mooij, G.C.A.M.; Frenkel, D.

    1993-01-01

    Above a substance's liquid–vapour critical point (i>Tc), the distinction between the liquid and vapour phases disappears. Below the triple point (T t), meanwhile (at which solid, liquid and vapour coexist), only the solid and vapour are stable. The liquid range, T c/T t, depends on the nature of the

  14. Determination of the solubility of low volatility liquid organic compounds in water using volatile-tracer assisted headspace gas chromatography.

    Science.gov (United States)

    Zhang, Shu-Xin; Chai, Xin-Sheng; Barnes, Donald G

    2016-02-26

    This study reports a new headspace gas chromatographic method (HS-GC) for the determination of water solubility of low volatility liquid organic compounds (LVLOs). The HS-GC analysis was performed on a set of aqueous solutions containing a range of concentrations of toluene-spiked (as a tracer) LVLOs, from under-saturation to over-saturation. A plot of the toluene tracer GC signal vs. the concentration of the LVLO results in two lines of different slopes that intersect at the concentration corresponding to the compound's solubility in water. The results showed that the HS-GC method has good precision (RSD solubility of LVLOs at elevated temperatures. This approach should be of special interest to those concerned about the impact of the presence of low-volatility organic liquids in waters of environmental and biological systems.

  15. Supported ionic liquid-phase (SILP) catalysis

    DEFF Research Database (Denmark)

    Riisager, Anders; Fehrmann, Rasmus; Wasserscheid, P.

    2005-01-01

    The concept of supported ionic liquid-phase (SILP) catalysis has been demonstrated for gas- and liquid-phase continuous fixed-bed reactions using rhodium phosphine catalyzed hydroformylation of propene and 1-octene as examples. The nature of the support had important influence on both the catalytic...

  16. Liquid-Phase Beam Pen Lithography.

    Science.gov (United States)

    He, Shu; Xie, Zhuang; Park, Daniel J; Liao, Xing; Brown, Keith A; Chen, Peng-Cheng; Zhou, Yu; Schatz, George C; Mirkin, Chad A

    2016-02-24

    Beam pen lithography (BPL) in the liquid phase is evaluated. The effect of tip-substrate gap and aperture size on patterning performance is systematically investigated. As a proof-of-concept experiment, nanoarrays of nucleotides are synthesized using BPL in an organic medium, pointing toward the potential of using liquid phase BPL to perform localized photochemical reactions that require a liquid medium. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Surface-tension-driven convection in pure liquid layers evaporating into ambient air: influence of liquid volatility

    Science.gov (United States)

    Chauvet, Fabien; Dehaeck, Sam; Colinet, Pierre

    2011-11-01

    The spontaneous surface-tension-driven convective patterns induced by evaporation of a pure liquid layer are studied experimentally. A volatile liquid layer placed in a cylindrical container is left free to evaporate into air at rest under ambient conditions. The thermal dynamics of the evaporating liquid layer is visualized using an infrared camera. Evaporation rate and liquid thickness are measured by weighting. We focus on the transition between the convective state and the conductive state appearing at a certain instant during the drying of the liquid layer. The critical Marangoni number Mac associated to this transition is estimated from evaporation rate and layer thickness measurements at this instant. The effect of the evaporation rate on Mac and kc (the critical wavenumber) has been investigated by changing the container height and, separately, the effect of the liquid volatility has been studied by using different liquids. Interestingly, it appears that Mac does not depend on the evaporation rate while it depends strongly on the liquid volatility. Given the typical uncertainties associated with liquid properties, a quite reasonable agreement is found with a ``one-sided'' linear stability analysis of this problem. Supported by ESA & BELSPO, by the EU, by ULB, and by FRS - FNRS.

  18. Chiral Liquid Crystals: Structures, Phases, Effects

    Directory of Open Access Journals (Sweden)

    Ingo Dierking

    2014-06-01

    Full Text Available The introduction of chirality, i.e., the lack of mirror symmetry, has a profound effect on liquid crystals, not only on the molecular scale but also on the supermolecular scale and phase. I review these effects, which are related to the formation of supermolecular helicity, the occurrence of novel thermodynamic phases, as well as electro-optic effects which can only be observed in chiral liquid crystalline materials. In particular, I will discuss the formation of helical superstructures in cholesteric, Twist Grain Boundary and ferroelectric phases. As examples for the occurrence of novel phases the Blue Phases and Twist Grain Boundary phases are introduced. Chirality related effects are demonstrated through the occurrence of ferroelectricity in both thermotropic as well as lyotropic liquid crystals. Lack of mirror symmetry is also discussed briefly for some biopolymers such as cellulose and DNA, together with its influence on liquid crystalline behavior.

  19. Computational and experimental study of the interactions between ionic liquids and volatile organic compounds.

    Science.gov (United States)

    Gao, Tingting; Andino, Jean M; Alvarez-Idaboy, J Raul

    2010-09-07

    Computational chemistry calculations were performed to investigate the interactions of ionic liquids with different classes of volatile organic compounds (VOCs), including alcohols, aldehydes, ketones, alkanes, alkenes, alkynes and aromatic compounds. At least one VOC was studied to represent each class. Initially, 1-butyl-3-methylimindazolium chloride (abbreviated as C(4)mimCl) was used as the test ionic liquid compound. Calculated interaction lengths between atoms in the ionic liquid and the VOC tested as well as thermodynamic data suggest that C(4)mimCl preferentially interacts with alcohols as compared to other classes of volatile organic compounds. The interactions of methanol with different kinds of ionic liquids, specifically 1-butyl-3-methylimidazolium bromine (C(4)mimBr) and 1-butyl-3-methylimidazolium tetrafluoroborate (C(4)mimBF(4)) were also studied. In comparing C(4)mimCl, C(4)mimBr, and C(4)mimBF(4), the computational results suggest that C(4)mimCl is more likely to interact with methanol. Laboratory experiments were performed to provide further evidence for the interaction between C(4)mimCl and different classes of VOCs. Fourier transform infrared spectroscopy was used to probe the ionic liquid surface before and after exposure to the VOCs that were tested. New spectral features were detected after exposure of C(4)mimCl to various alcohols. The new features are characteristic of the alcohols tested. No new IR features were detected after exposure of the C(4)mimCl to the aldehyde, ketone, alkane, alkene, alkyne or aromatic compounds studied. In addition, after exposing the C(4)mimCl to a multi-component mixture of various classes of compounds (including an alcohol), the only new peaks that were detected were characteristic of the alcohol that was tested. These experimental results demonstrated that C(4)mimCl is selective to alcohols, even in complex mixtures. The findings in this work provide information for future gas-phase alcohol sensor design.

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

    Science.gov (United States)

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

    2016-08-03

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

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

    Science.gov (United States)

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

    2016-03-01

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

  2. Experimental Study of the Influence of Operating Position on the Behavior of an Electromechanical Actuator with Volatile Liquid

    Directory of Open Access Journals (Sweden)

    NITAN Ilie

    2013-05-01

    Full Text Available This paper presents an experimental study of the influence of operating position on the behavior of an electrochemical actuator with volatile liquid. In the introduction, the operating principle of electromechanical actuators with volatile liquid is described. Are then presented experimental stand used, the study results and conclusions drawn from the studies.

  3. Binary Solid-Liquid Phase Equilibria

    Science.gov (United States)

    Ellison, Herbert R.

    1978-01-01

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

  4. Purge and trap method to determine alpha factors of VOC liquid-phase mass transfer coefficients

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A theoretical approach and laboratory practice of determining the alpha factors of volatile organic compound (VOC) liquid-phase mass transfer coefficients are present in this study.Using Purge Trap Concentrator, VOC spiked water samples are purged by high-purity nitrogen in the laboratory, the VOC liquid-phase mass transfer rate constants under the laboratory conditions are then obtained by observing the variation of VOCs purged out of the water with the purge time.The alpha factors of VOC liquid-phase mass transfer coefficients are calculated as the ratios of the liquid-phase mass transfer rate constants in real water samples to their counterparts in pure water under the same experimental conditions. This direct and fast approach is easy to control in the laboratory, and would benefit mutual comparison among researchers, so might be useful for thestudy of VOC mass transfer across the liquid-gas interface.

  5. Simultaneous Distillation Extraction of Some Volatile Flavor Components from Pu-erh Tea Samples—Comparison with Steam Distillation-Liquid/Liquid Extraction and Soxhlet Extraction

    Science.gov (United States)

    Gu, Xungang; Zhang, Zhengzhu; Wan, Xiaochun; Ning, Jingming; Yao, Chengcheng; Shao, Wanfang

    2009-01-01

    A simutaneous distillation extraction (SDE) combined GC method was constructed for determination of volatile flavor components in Pu-erh tea samples. Dichloromethane and ethyl decylate was employed as organic phase in SDE and internal standard in determination, respectively. Weakly polar DB-5 column was used to separate the volatile flavor components in GC, 10 of the components were quantitatively analyzed, and further confirmed by GC-MS. The recovery covered from 66.4%–109%, and repeatability expressed as RSD was in range of 1.44%–12.6%. SDE was most suitable for the extraction of the anlytes by comparing with steam distillation-liquid/liquid extraction and Soxhlet extraction. Commercially available Pu-erh tea samples, including Pu-erh raw tea and ripe tea, were analyzed by the constructed method. the high-volatile components, such as benzyl alcohol, linalool oxide, and linalool, were greatly rich in Pu-erh raw teas, while the contents of 1,2,3-Trimethoxylbenzene and 1,2,4-Trimethoxylbenzene were much high in Pu-erh ripe teas. PMID:20169174

  6. Increasing the isolated quantities and purities of volatile compounds by using a triple Deans-switch multidimensional preparative gas chromatographic system with an apolar-wax-ionic liquid stationary-phase combination.

    Science.gov (United States)

    Sciarrone, Danilo; Pantò, Sebastiano; Ragonese, Carla; Tranchida, Peter Quinto; Dugo, Paola; Mondello, Luigi

    2012-08-21

    A novel preparative-scale triple gas chromatographic system, equipped with three Deans-switch devices, is herein described. The isolation of volatile compounds was achieved by using a lab-made collection system. Considerations are made on the possibility to inject high volumes of neat sample, maintaining, at the same time, high resolution levels. The degree of recovery of a series of compounds, characterized by a differing volatility, is also reported. In this respect, different collection conditions were evaluated, namely, the presence (or not) of packing material as well as CO(2) cooling, in various combinations. Finally, the interconnected features, that is time requirements and the isolation of "acceptable" analyte quantities (e.g., milligram level for NMR characterization), are related to parameters such as analyte concentration, injected volume, collection conditions, and number of GC runs. The results herein reported will demonstrate the need for a high-resolution GC step, prior to analyte collection, in the prep-GC analysis of complex samples.

  7. Fast analysis of volatile organic compounds and disinfection by-products in drinking water using solid-phase microextraction-gas chromatography/time-of-flight mass spectrometry.

    Science.gov (United States)

    Niri, Vadoud H; Bragg, Leslie; Pawliszyn, Janusz

    2008-08-08

    A fast method was developed for the extraction and analysis of volatile organic compounds, including disinfection by-products (DBPs), with headspace solid-phase microextraction (HS-SPME) and gas chromatography/mass spectrometry (GC/MS) techniques. A GC/time-of-flight (TOF)-MS instrument, which had fast acquisition rates and powerful deconvolution software, was used. Under optimum conditions total runtime was 45s. Volatile organic compounds (VOCs), including purgeable A and B compounds (listed in US Environmental Protection Agency method 624), were identified in standard water samples. Extraction times were 1min for more volatile compounds and 2min for less volatile compounds. The method was applied to the analysis of water samples treated under different disinfection processes and the results were compared with those from a liquid-liquid extraction method.

  8. Headspace solid-phase microextraction for wine volatile analysis.

    Science.gov (United States)

    Azzi-Achkouty, Samar; Estephan, Nathalie; Ouaini, Naïm; Rutledge, Douglas N

    2017-07-03

    The most commonly used technique to prepare samples for the analysis of wine volatile is the headspace solid-phase microextraction (HS-SPME). This method has gained popularity in last few years, as it is a unique solventless preparation technique. In this paper, a summary of recently published studies using HS-SPME for the analysis of wine aromas, with special emphasis on the method developed, has been compiled. Several papers are discussed in detail, mainly with respect to the SPME conditions used. A brief summary of the reviews related to HS-SPME analysis is given and discussed. Several parameters affecting the HS-SPME, such as the salt concentration and the agitation conditions, are used in the same way as used in several papers. The HS-SPME extraction proved to be sufficiently sensitive to satisfy legislative requirements related to low detection and quantification limits as well as method accuracy and precision requirements. However, in order to achieve the best performance and precision, the protocol needs to be optimized for each case. The effect of different parameters must be well characterized to ensure correct extraction and desorption to ensure the transfer of extracted compounds into the analytical system. The operating parameters, such as time, temperature, and agitation, must then be kept constant for all the samples.

  9. Lyotropic Liquid Crystal Phases from Anisotropic Nanomaterials

    Directory of Open Access Journals (Sweden)

    Ingo Dierking

    2017-10-01

    Full Text Available Liquid crystals are an integral part of a mature display technology, also establishing themselves in other applications, such as spatial light modulators, telecommunication technology, photonics, or sensors, just to name a few of the non-display applications. In recent years, there has been an increasing trend to add various nanomaterials to liquid crystals, which is motivated by several aspects of materials development. (i addition of nanomaterials can change and thus tune the properties of the liquid crystal; (ii novel functionalities can be added to the liquid crystal; and (iii the self-organization of the liquid crystalline state can be exploited to template ordered structures or to transfer order onto dispersed nanomaterials. Much of the research effort has been concentrated on thermotropic systems, which change order as a function of temperature. Here we review the other side of the medal, the formation and properties of ordered, anisotropic fluid phases, liquid crystals, by addition of shape-anisotropic nanomaterials to isotropic liquids. Several classes of materials will be discussed, inorganic and mineral liquid crystals, viruses, nanotubes and nanorods, as well as graphene oxide.

  10. Ultrasonic atomization: effect of liquid phase properties.

    Science.gov (United States)

    Avvaru, Balasubrahmanyam; Patil, Mohan N; Gogate, Parag R; Pandit, Aniruddha B

    2006-02-01

    Experiments have been conducted to understand the mechanism by which the ultrasonic vibration at the gas liquid interface causes the atomization of liquid. For this purpose, aqueous solutions having different viscosities and liquids showing Newtonian (aqueous solution of glycerin) and non-Newtonian behavior (aqueous solution of sodium salt of carboxy methyl cellulose) were employed. It has been found that the average droplet size produced by the pseudo-plastic liquid is less than that produced by the viscous Newtonian liquid having viscosity equal to zero-shear rate viscosity of the shear thinning liquid. The droplet size was found to increase initially with an increase in the viscosity up to a certain threshold viscosity after which the droplet size was found to decrease again. Also droplet size distribution is found to be more compact (uniform sizes) with an increasing viscosity of the atomizing liquid. The presence of the cavitation and its effect on the atomization has been semi quantitatively confirmed using energy balance and by the measurement of the droplet ejection velocities and validated on the basis of the decomposition of the aqueous KI solution. A correlation has been proposed for the prediction of droplet size for aqueous Newtonian fluids and fluids showing non-Newtonian behavior based on the dimensionless numbers incorporating the operating parameters of the ultrasonic atomizer and the liquid phase physico-chemical properties.

  11. Role of Aerosol Liquid Water in Secondary Organic Aerosol Formation from Volatile Organic Compounds.

    Science.gov (United States)

    Faust, Jennifer A; Wong, Jenny P S; Lee, Alex K Y; Abbatt, Jonathan P D

    2017-02-07

    A key mechanism for atmospheric secondary organic aerosol (SOA) formation occurs when oxidation products of volatile organic compounds condense onto pre-existing particles. Here, we examine effects of aerosol liquid water (ALW) on relative SOA yield and composition from α-pinene ozonolysis and the photooxidation of toluene and acetylene by OH. Reactions were conducted in a room-temperature flow tube under low-NOx conditions in the presence of equivalent loadings of deliquesced (∼20 μg m(-3) ALW) or effloresced (∼0.2 μg m(-3) ALW) ammonium sulfate seeds at exactly the same relative humidity (RH = 70%) and state of wall conditioning. We found 13% and 19% enhancements in relative SOA yield for the α-pinene and toluene systems, respectively, when seeds were deliquesced rather than effloresced. The relative yield doubled in the acetylene system, and this enhancement was partially reversible upon drying the prepared SOA, which reduced the yield by 40% within a time scale of seconds. We attribute the high relative yield of acetylene SOA on deliquesced seeds to aqueous partitioning and particle-phase reactions of the photooxidation product glyoxal. The observed range of relative yields for α-pinene, toluene, and acetylene SOA on deliquesced and effloresced seeds suggests that ALW plays a complicated, system-dependent role in SOA formation.

  12. Evaporation release behavior of volatile fission products from liquid sodium pool to the inert cover gas

    Energy Technology Data Exchange (ETDEWEB)

    Nakagiri, T.; Miyahara, S. [Oarai Engineering Center, Power Reactor and Nuclear Fuel Development Corp., Oaraimachi, Ibaraki (Japan)

    1996-12-01

    In fuel failure of sodium cooled fast breeder reactors, released volatile fission products (VFPs) such as iodine and cesium from the fuel will be dissolved into the liquid sodium coolant and transferred to the cover vaporization. In the cover gas system of the reactor, natural convection occurs due to temperature differences between the sodium pool and the gas phase. The release rates of VFPs together with sodium vaporization are considered to be controlled by the convection. In this study, three analytical models are developed and examined to calculate the transient release rates using the equilibrium partition coefficients of VFPs. The calculated release rates are compared with experimental results for sodium and sodium iodide. The release rate of sodium is closest to the calculation by the heterogeneous nucleation theory. The release rate of sodium iodide obtained from the experiment is between the release rates calculated by the model based on heat-and-mass transfer analogy and the Hill`s theory. From this study, it is confirmed that the realistic release rate of sodium is able to be calculated by the model based on the heterogeneous nucleation theory. The conservative release rate of sodium iodide is able to be calculated by the model based on the Hill`s theory using the equilibrium partition coefficient of sodium iodide. (author) 7 figs., 1 tab., 3 refs.

  13. Liquid gas phase transition in hypernuclei

    CERN Document Server

    Mallik, S

    2016-01-01

    The fragmentation of excited hypernuclear system formed in heavy ion collisions has been described by the canonical thermodynamical model extended to three component systems. The multiplicity distribution of the fragments has been analyzed in detail and it has been observed that the hyperons have the tendency to get attached to the heavier fragments. Another important observation is the phase coexistence of the hyperons, a phenomenon which is linked to liquid gas phase transition in strange matter.

  14. Gravitational Role in Liquid Phase Sintering

    Science.gov (United States)

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

    1998-01-01

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

  15. Partition of volatile compounds in pea globulin-maltodextrin aqueous two-phase system.

    Science.gov (United States)

    Nguyen, Thanh Dat; Lafarge, Céline; Murat, Chloé; Mession, Jean-Luc; Cayot, Nathalie; Saurel, Rémi

    2014-12-01

    This study is based on the assumption that the off-flavour of pea proteins might be decreased using the retention of volatile compounds by a mixture with another biopolymer. The partition of volatile compounds in an aqueous system containing pea protein and maltodextrins was followed under thermodynamic incompatibility conditions. Firstly, the phase diagram of the system was established. Then, the partition of aroma compounds between the phase rich in protein and the phase rich in maltodextrin was measured by SPME-GC-MS. There was a transfer of volatile compounds during phase separation. Variations of pH were also used to vary the retention of volatile compounds by proteins. The concentration of volatile compounds in protein solution at pH 2.4 was higher than at pH 7.2. It was possible to increase the transfer of volatile compounds from the phase rich in protein to the phase rich in maltodextrin using the effect of pH on protein denaturation.

  16. Contact line pinning of a perfectly wetting and volatile liquid at a sharp edge

    Science.gov (United States)

    Tsoumpas, Yannis; Dehaeck, Sam; Rednikov, Alexey; Colinet, Pierre

    2011-11-01

    According to the Gibbs' criterion, a sharp edge can act as an energy barrier during the spreading of a liquid drop on a rigid substrate. In this study, however, we are trying to determine experimentally whether Gibbs' criterion is also valid for the case of a perfectly wetting and volatile liquid. To this purpose, we constructed a groove of triangular cross section on a Plexiglas substrate. During the experiments liquid was injected in the region surrounded by the groove, which had a square shape with rounded corners. The results indicated that a microgroove edge can indeed prevent the spreading of the liquid drop up to a certain extent, with the maximum apparent contact angle being in close agreement with the one given by Gibbs' criterion. Nevertheless, the apparent contact angle at breakup was found to be significantly lower in the corner of our region. To study this further we developed a static model, which takes into account surface tension and gravity but not the evaporation. Both the simulations and the experiments have confirmed a remarkable behaviour of the contact line at the corner. Finally, to grasp the effect of evaporation, experiments have also been conducted with drops of equally wetting but less volatile liquids. Supported by ESA & BELSPO, by the EU, and by FRS-FNRS.

  17. Phases in the active liquid phase methanol synthesis catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Sawant, A.V.; Lee, S.; Kulik, C.J.

    1988-01-01

    An attempt has been made to identify the phases present in the active catalyst for liquid phase methanol synthesis. X-ray powder diffraction was used to identify the phases. Only metallic Cu was detected, while no Cu/sup +/ species was found to be present. A significant amount of ZnCO/sub 3/ was found to be present in catalysts which had been subjected to high partial pressures of CO/sub 2/. This fact has hitherto not been reported in literature. Some speculations about the effect of ZnCO/sub 3/ on the life of the catalyst are made. 21 refs., 6 figs.

  18. Crystal-liquid-gas phase transitions and thermodynamic similarity

    CERN Document Server

    Skripov, Vladimir P; Schmelzer, Jurn W P

    2006-01-01

    Professor Skripov obtained worldwide recognition with his monograph ""Metastable liquids"", published in English by Wiley & Sons. Based upon this work and another monograph published only in Russia, this book investigates the behavior of melting line and the properties of the coexisting crystal and liquid phase of simple substances across a wide range of pressures, including metastable states of the coexisting phases. The authors derive new relations for the thermodynamic similarity for liquid-vapour phase transition, as well as describing solid-liquid, liquid-vapor and liquid-liquid phase tra

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

    Science.gov (United States)

    Bermúdez-Salguero, Carolina; Gracia-Fadrique, Jesús

    2015-08-13

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

  20. Solid phase microextraction for profiling volatile compounds in liquered white wines

    Directory of Open Access Journals (Sweden)

    Henryk H. Jeleń

    2010-03-01

    Full Text Available Background. Profile of volatile compounds is a distinct feature of wine, which is dependent on the type of wine, grapes, fermentation and ageing processes. Profiling volatile compounds in wine using fast method provides information on major groups of compounds and can be used for classification/differentiation purposes. Solid phase microextraction (SPME was used for the profiling of volatile compounds in liquered white wines in this study. Material and methods. Different fibers were tested for this purpose: PDMS, Carboxene/ PDMS, Carboxene/DVB/PDMS, Polyacrylate, Divinylbenzene/PDMS. Different times were compared to optimize extraction process. Profile and amount of volatile compounds extracted by SPME fiber was compared for eight liquered white wines. Results. Carboxene/DVB/PDMS showed the highest efficiency in extracting higher alcohols, esters, carbonyls and terpenes. Of tested extraction times ranging from 5 to 30 min. 20 minutes was chosen providing sufficient peak responses. Using SPME total amount of volatile compounds in eight liquered wines was compared – Riversaltes, Offley Porto and Jutrzenka having the highest amount of adsorbed volatiles. Profiles of volatiles of analysed wines revealed that dominating compounds in 6 wines were esters, followed by higher alcohols, two analysed Muscat wines had high terpene contents compared to remaining wines. Conclusion. SPME can be used for relatively fast profiling of wine volatiles, that can be used for wines classification.  

  1. A reexamination of the relationship between volatility, liquidity and trading activity

    Directory of Open Access Journals (Sweden)

    Khine Kyaw

    2013-03-01

    Full Text Available Este trabajo investiga si la relación entre actividad negociadora en el mercado de acciones, la liquidez del mercado y la volatilidad a nivel de cartera, es similar a dicha relación a nivel deacciones individuales. Para las carteras de empresas de mayor tamaño, la mayor actividad negociadora está relacionada con mayor liquidez y más volatilidad. Sin embargo, a pesar de quela relación volatilidad-liquidez es la misma para las carteras de acciones pequeñas, encontramos que la mayor actividad negociadora está negativamente asociada con la liquidez para estaagrupación. Este contraste en las relaciones está causado por las interrelaciones dinámicas entre las tres variables y una vez que se controla por esas interrelaciones, dicho contraste en losresultados desparece. Estos hallazgos contribuyen al debate sobre el comportamiento del mercado, que ha adquirido un renovado interés en los últimos años.We investigate whether the relationship between equity trading activity, market liquidity and return volatility at the portfolio level is similar to the relationship at the individual security level. For the very largest firm-size portfolio, higher trading activity is positively associated with greater liquidity and more volatile returns. However, despite the volatility-liquidity relationship being the same for smaller equity portfolios, we find that higher trading activity is negatively associated with liquidity for this grouping. These contrasting relationships are shown to be caused by the interdynamics between all three variables and once we control for these interrelationships, the contrasting results disappear. The findings contribute to the debate on market behaviour that has taken on renewed vigour in recent years.

  2. Monodomain Blue Phase Liquid Crystal Layers for Phase Modulation

    Science.gov (United States)

    Oton, E.; Netter, E.; Nakano, T.; D.-Katayama, Y.; Inoue, F.

    2017-03-01

    Liquid crystal “Blue Phases” (BP) have evolved, in the last years, from a scientific curiosity to emerging materials for new photonic and display applications. They possess attractive features over standard nematic liquid crystals, like submillisecond switching times and polarization- independent optical response. However, BPs still present a number of technical issues that prevent their use in practical applications: their phases are only found in limited temperature ranges, thus requiring stabilization of the layers; stabilized BP layers are inhomogeneous and not uniformly oriented, which worsen the optical performance of the devices. It would be essential for practical uses to obtain perfectly aligned and oriented monodomain BP layers, where the alignment and orientation of the cubic lattice are organized in a single 3D structure. In this work we have obtained virtually perfect monodomain BP layers and used them in devices for polarization independent phase modulation. We demonstrate that, under applied voltage, well aligned and oriented layers generate smoother and higher values of the phase shift than inhomogeneous layers, while preserving polarization independency. All BP devices were successfully stabilized in BPI phase, maintaining the layer monodomain homogeneity at room temperature, covering the entire area of the devices with a unique BP phase.

  3. Monodomain Blue Phase Liquid Crystal Layers for Phase Modulation

    Science.gov (United States)

    Oton, E.; Netter, E.; Nakano, T.; D.-Katayama, Y.; Inoue, F.

    2017-01-01

    Liquid crystal “Blue Phases” (BP) have evolved, in the last years, from a scientific curiosity to emerging materials for new photonic and display applications. They possess attractive features over standard nematic liquid crystals, like submillisecond switching times and polarization- independent optical response. However, BPs still present a number of technical issues that prevent their use in practical applications: their phases are only found in limited temperature ranges, thus requiring stabilization of the layers; stabilized BP layers are inhomogeneous and not uniformly oriented, which worsen the optical performance of the devices. It would be essential for practical uses to obtain perfectly aligned and oriented monodomain BP layers, where the alignment and orientation of the cubic lattice are organized in a single 3D structure. In this work we have obtained virtually perfect monodomain BP layers and used them in devices for polarization independent phase modulation. We demonstrate that, under applied voltage, well aligned and oriented layers generate smoother and higher values of the phase shift than inhomogeneous layers, while preserving polarization independency. All BP devices were successfully stabilized in BPI phase, maintaining the layer monodomain homogeneity at room temperature, covering the entire area of the devices with a unique BP phase. PMID:28281691

  4. Non-conventional gas phase remediation of volatile halogenated compounds by dehydrated bacteria

    OpenAIRE

    Erable, Benjamin; Goubet, Isabelle; Seltana, Amira; Maugard, Thierry

    2009-01-01

    Traditional biological removal processes are limited by the low solubility of halogenated compounds in aqueous media. A new technology appears very suitable for the remediation of these volatile organic compounds (VOCs). Solid/gas bio-catalysis applied in VOC remediation can transform halogenated compounds directly in the gas phase using dehydrated cells as a bio-catalyst. The hydrolysis of volatile halogenated substrates into the corresponding alcohol was studied in a solid/gas bio...

  5. Groundwater cleanup by in-situ sparging. IX. Air channeling model for nonaqueous phase liquid removal

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, D.J.; Norris, R.D.; Clarke, A.N. [Eckenfelder, Inc., Nashville, TN (United States)

    1996-04-01

    A mathematical model is developed to simulate the removal of dissolved and nonaqueous phase liquid (NAPL) volatile organic compounds (VOCs) from contaminated aquifers by sparging. The model assumes that the sparging air moves through the aquifer in persistent channels and that NAPL must dissolve and move to these channels by diffusion and dispersion processes. The dependence of the model results on model parameters is explored, and practical implications for sparging well operation are discussed.

  6. Liquid-Liquid-Liquid Three Phase Extraction Apparatus: Operation Strategy and Influences on Mass Transfer Efficiency

    Institute of Scientific and Technical Information of China (English)

    何秀琼; 黄昆; 于品华; 张超; 谢铿; 李鹏飞; 王娟; 安震涛; 刘会洲

    2012-01-01

    Abstract A new mixer-settler-mixer three chamber integrated extractor is proposed in this work for liquid-liquid- liquid three phase countercurrent and continuous extraction. Experiments revealed the influences of the structural design of the three-liquid-phase extractor and some key operational parameters on three-phase partition of two phenolic isomers, p-nitrophenol (p-NP) and o-nitrophenol (o-NP). The model three-liquid-phase extraction system used here is nonane (organic top-plaase)-polyethylene glycol (PEG 20UU) (polymer mlddle-phase)-(NH4)2SO4 aqueous solution (aqueous bottom-phase). It is indicated that agitating speed and retention time in three-phase mixer are key parameters to extraction fraction of nitrophenol. Dispersion band behavior is related to agitating intensity, and its occurrence does not affect the extraction fraction of target compounds. The present work highlights the possibility of a feasible approach of scaling up of the proposed three-phase extraction apparatus for future in- dustrial-aimed applications.

  7. Analysis of volatile organic compounds in pleural effusions by headspace solid-phase microextraction coupled with cryotrap gas chromatography and mass spectrometry.

    Science.gov (United States)

    Huang, Zhongping; Zhang, Jie; Zhang, Peipei; Wang, Hong; Pan, Zaifa; Wang, Lili

    2016-07-01

    Headspace solid-phase microextraction coupled with cryotrap gas chromatography and mass spectrometry was applied to the analysis of volatile organic compounds in pleural effusions. The highly volatile organic compounds were separated successfully with high sensitivity by the employment of a cryotrap device, with the construction of a cold column head by freezing a segment of metal capillary with liquid nitrogen. A total of 76 volatile organic compounds were identified in 50 pleural effusion samples (20 malignant effusions and 30 benign effusions). Among them, 34 more volatile organic compounds were detected with the retention time less than 8 min, by comparing with the normal headspace solid-phase microextraction coupled with gas chromatography and mass spectrometry method. Furthermore, 24 volatile organic compounds with high occurrence frequency in pleural effusion samples, 18 of which with the retention time less than 8 min, were selected for the comparative analysis. The results of average peak area comparison and box-plot analysis showed that except for cyclohexanone, 2-ethyl-1-hexanol, and tetramethylbenzene, which have been reported as potential cancer biomarkers, cyclohexanol, dichloromethane, ethyl acetate, n-heptane, ethylbenzene, and xylene also had differential expression between malignant and benign effusions. Therefore, the proposed approach was valuable for the comprehensive characterization of volatile organic compounds in pleural effusions.

  8. Thermodynamic Study of the Role of Interface Curvature on Multicomponent Vapor-Liquid Phase Equilibrium.

    Science.gov (United States)

    Shardt, Nadia; Elliott, Janet A W

    2016-04-14

    The effect of interface curvature on phase equilibrium has been much more studied for single-component than multicomponent systems. We isolate the effect of curvature on multicomponent vapor-liquid equilibrium (VLE) phase envelopes and phase composition diagrams using the ideal system methanol/ethanol and the nonideal system ethanol/water as illustrative examples. An important finding is how nanoscale interface curvature shifts the azeotrope (equal volatility point) of nonideal systems. Understanding of the effect of curvature on VLE can be exploited in future nanoscale prediction and design.

  9. Analysis of Pyrazine and Volatile Compounds in Cocoa Beans Using Solid Phase Microextraction

    Directory of Open Access Journals (Sweden)

    Misnawi Jati

    2011-05-01

    Full Text Available Analisis pirazin dan senyawa volatil pada biji kakao dilakukan dengan perangkat mikroekstraksi fase padat (solid phase micro extraction, SPME, untuk mengembangkan metode ekstraksi tanpa pelarut yang efisien. Perangkat SPME dilengkapi fiber stableflex dengan polimer DVB/Carboxen/PDMS yang menjerap senyawa volatil di area headspace. Biji kakao terfermentasi disangrai dan diambil lemaknya untuk ditempatkan dalam botol bertutup septa. Sampel dipanaskan pada suhu 70OC dan serat SPME ditusukkan menembus septa untuk mengekstrak senyawa volatil dari lemak kakao selama 30 menit. Senyawa volatil lemak kakao akan dijerap oleh serat SPME dan dilepaskan kembali untuk analisis kromatografi gas. Penelitian menunjukkan pirazin dan senyawa volatil yang diekstrak oleh serat SPME dapat terdeteksi dengan baik oleh kromatografi gas. Area puncak yang dihasilkan SPME meliputi 2,83–5,35% dari area puncak yang dihasilkan syringe, kendati demikian kemampuan ekstraksi SPME dapat disetarakan dengan syringe. Lima jenis pirazin yang sering terdapat di biji kakao telah diidentifikasi, meliputi metil pirazin (2MP; 2,3 dan 2,5-dimetilpirazin (DMP; dan 2,3,5 trimetilpirazin (TrMP dan tetrametil pirazin (TMP. Senyawa lainnya juga terdeteksi meliputi alkohol, asam karboksilat, aldehida, keton, ester, pirazin, amin dan senyawa volatil lainnya, dan diketahui erat kaitannya dengan aroma khas cokelat. Keberhasilan SPME dalam ekstraksi pirazin dan senyawa volatilsemi volatil yang berperan penting dalam pembentukan aroma cokelat menandakan SPME dapat digunakan lebih lanjut untuk analisis citarasa.

  10. Change of volatile components in six microalgae with different growth phases.

    Science.gov (United States)

    Zhou, Lv; Chen, Jiao; Xu, Jilin; Li, Yan; Zhou, Chengxu; Yan, Xiaojun

    2017-02-01

    Head space solid-phase microextraction-gas chromatography-mass spectrometry has been applied to analyze the volatile components of six marine microalgae (Thalassiosira weissflogii, Nitzschia closterium, Chaetoceros calcitrans, Platymonas helgolandica, Nannochloropsis spp. and Dicrateria inornata) from Bacillariophyta, Chlorophyta and Chrysophyta, respectively, in different growth phases. All volatile compounds were identified by database searching in the NIST08 Mass Spectral Library and analyzed by principal component analysis with SIMCA-P software (Umetrics, Umea, Sweden). The results clearly revealed that the volatile components of the six microalgae were significantly different in the exponential, stationary and declining phases. Aldehydes, alkanes, some esters and dimethyl sulfide significantly changed in different growth phases. This is the first report on the comprehensive characteristics of volatile components in different microalgae and in different growth phases. The results may provide reference data for studies on the flavor of cultivated aquatic organism, odor formation in nature water, choice of feeding period and microalgae species selection for the artificial rearing of marine organisms. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  11. Gas flow headspace liquid phase microextraction.

    Science.gov (United States)

    Yang, Cui; Qiu, Jinxue; Ren, Chunyan; Piao, Xiangfan; Li, Xifeng; Wu, Xue; Li, Donghao

    2009-11-06

    There is a trend towards the use of enrichment techniques such as microextraction in the analysis of trace chemicals. Based on the theory of ideal gases, theory of gas chromatography and the original headspace liquid phase microextraction (HS-LPME) technique, a simple gas flow headspace liquid phase microextraction (GF-HS-LPME) technique has been developed, where the extracting gas phase volume is increased using a gas flow. The system is an open system, where an inert gas containing the target compounds flows continuously through a special gas outlet channel (D=1.8mm), and the target compounds are trapped on a solvent microdrop (2.4 microL) hanging on the microsyringe tip, as a result, a high enrichment factor is obtained. The parameters affecting the enrichment factor, such as the gas flow rate, the position of the microdrop, the diameter of the gas outlet channel, the temperatures of the extracting solvent and of the sample, and the extraction time, were systematically optimized for four types of polycyclic aromatic hydrocarbons. The results were compared with results obtained from HS-LPME. Under the optimized conditions (where the extraction time and the volume of the extracting sample vial were fixed at 20min and 10mL, respectively), detection limits (S/N=3) were approximately a factor of 4 lower than those for the original HS-LPME technique. The method was validated by comparison of the GF-HS-LPME and HS-LPME techniques using data for PAHs from environmental sediment samples.

  12. Structure of phase-separated ferroelectric/ semiconducting polymer blends for organic non-volatile memories

    NARCIS (Netherlands)

    Mcneill, C.R.; Asadi, K.; Watts, B.; Blom, P.W.M.; Leeuw, D.M. de

    2010-01-01

    The phase-separated structure of blends of the ferroelectric polymer P(VDF-TrFE) and the semiconducting polymer P3HT used in organic non-volatile memories is revealed with soft X-ray spectromicroscopy. These thin-film blends show a columnar morphology, with P3HT-rich columns enclosed in a continuous

  13. Prediction of the vapor-liquid distribution constants for volatile nonelectrolytes in water up to its critical temperature

    Science.gov (United States)

    Plyasunov, Andrey V.; Shock, Everett L.

    2003-12-01

    The distribution of solutes between coexisting liquid and vapor phases of water can be expressed by the distribution constant, K D, defined as K D= limitlim x→0y/x, where y and x stand for the mole fraction concentrations of a solute in vapor and liquid phases, respectively. Research reported here is concerned with the prediction of this property, K D, for volatile nonelectrolytes, over the whole temperature range of existence of the vapor-liquid equilibrium for water, i.e. from 273 K to the critical temperature at 647.1 K. A simple empirical method is proposed to extrapolate the values of K D from 298 K to 500-550 K. Calculations at higher temperatures are based on the theoretical relation that establishes the proportionality between RTlnK D and the Krichevskii parameter, A Kr, which is the single most important property of a solute at near-critical conditions, and can be evaluated using the method proposed here. The comparison of predicted and experimental values of K D and A Kr for a few well-studied solutes reveals the satisfactory performance of the proposed method. It appears that the accuracy of predictions in the framework of this method is limited mainly by the accuracy of the values of the thermodynamic functions of hydration of solutes at 298 K, and that the best way to improve the quality of predictions of K D and A Kr is to increase the inventory of accurate calorimetric enthalpy and heat capacity data for aqueous solutes at 298 K. We stress that the values of the Krichevskii parameter, such as those generated in this study, are of crucial importance for reliable predictions of the chemical potential and its derivatives (V 2o, Cp 2o) for aqueous solutes at near-critical and supercritical conditions. Values of K D and A Kr are predicted for many inorganic volatile nonelectrolytes and some halogenated derivatives of methane and ethene. We show that both ln K D and A Kr for aqueous organic solutes follow group additivity systematics, and we derive a set

  14. Rising and boiling of a drop of volatile liquid in a heavier one: application to the LMFBR severe accidents

    Energy Technology Data Exchange (ETDEWEB)

    Pigny, Sylvain L.; Coste, Pierre F. [DEN/DER/SSTH, CEA/Grenoble, 38054 Grenoble Cedex 9 (France)

    2005-07-01

    Full text of publication follows: The rising and, simultaneously the boiling, of a droplet of volatile liquid in a heavier one is computation-ally investigated. Our calculations are performed with the help of the SIMMER code, in which a specific DNS algorithm is developed, to represent surface tension between the different media in an explicit way. This is required to represent the physical contact that occurs between two liquids and the vapor from the lighter one, since interfacial heat transfers, and therefore boiling kinetics, merely depend on it. The behavior of the three fluids system is of interest as a key phenomenon related to the transition phase of LMFBR severe accidents, before the formation of a fully developed bubble column. The driven force due to the boiling of steel drops can play a major role in the relocation, and, consequently, the recriticality of UO{sub 2} fuel. The problem is investigated focusing first on analytical experiments, built-up with simulating materials, and for which accurate experimental results are provided. The dependence of results with regard to thermodynamical and physical properties is underlined. This point is of interest in view of some uncertainties in the knowledge of data concerning the materials present in the reactor at high temperature. The pressure level is a key parameter in the accident scenarios: its influence is uppermost on the volumic mass of the gas. It is also outlined. (authors)

  15. Pinning of a perfectly wetting volatile liquid at a sharp edge - experiment and theory

    Science.gov (United States)

    Tsoumpas, Yannis; Dehaeck, Sam; Rednikov, Alexey; Galvagno, Mariano; Thiele, Uwe; Colinet, Pierre

    2012-11-01

    It is well known that contact lines of drops, even those of wetting liquids, stay pinned at sharp edges of the substrate until the apparent contact angle exceeds a critical value. In the present study, we show that evaporation influences this effect. The edge of a circular groove is used as an example. Experiments with wetting liquids of different evaporation rate show indeed that not only the spreading of the liquid is adequately halted, but also that the pinning is enhanced for the more volatile cases. The experimental results are qualitatively compared with predictions of a thin film model in two dimensions. The approach employs an evolution equation for the height profile of an evaporating thin film (small contact angle droplet) on a substrate with a rounded edge, and enables one to predict the dependence of the apparent contact angle on the position of the contact line. The calculations confirm our experimental observations, namely that there exists a dynamically produced critical angle for depinning that increases with the evaporation rate. This suggests that one may introduce a simple modification of the Gibbs criterion for pinning that accounts for the non-equilibrium effect of evaporation. Supported by the Marie Curie MULTIFLOW Network, by ESA & BELSPO, and by FRS-FNRS.

  16. A volatile fluid assisted thermo-pneumatic liquid metal energy harvester

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Jianbo, E-mail: zhouyuan@mail.ipc.ac.cn, E-mail: jianbotang@mail.ipc.ac.cn [Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Wang, Junjie; Liu, Jing; Zhou, Yuan, E-mail: zhouyuan@mail.ipc.ac.cn, E-mail: jianbotang@mail.ipc.ac.cn [Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

    2016-01-11

    A close-cycle self-driving thermal energy harvester using liquid metal as energy carrier fluid has been proposed. The driving force that pushes the liquid metal against flow resistance and gravity is provided by a resistively heated volatile fluid based on thermo-pneumatic principle. The tested harvester prototype demonstrated its capability to extract thermal energy between small temperature gradient, at a scale of 10 °C. During a 5-h operation, it further demonstrated robust liquid metal recirculating performance at a time-average volume flow rate of 14 ml/min with a 12.25 W heating load. The prototype also managed to self-adjust to variable working conditions which indicated the reliability of this method. Advantages of this method include simple-structural design, rigid-motion free operation, and low-temperature actuation. These advantages make it uniquely suited for solar energy and low-grade heat harvesting, high heat flux electronics cooling, as well as autonomous machines actuating.

  17. Thermomorphic phase separation in ionic liquid-organic liquid systems - conductivity and spectroscopic characterization

    DEFF Research Database (Denmark)

    Riisager, Anders; Fehrmann, Rasmus; Berg, Rolf W.;

    2005-01-01

    Electrical conductivity, FT-Raman and NMR measurements are demonstrated as useful tools to probe and determine phase behavior of thermomorphic ionic liquid-organic liquid systems. To illustrate the methods, consecutive conductivity measurements of a thermomorphic methoxyethoxyethyl-imidazolium io......Electrical conductivity, FT-Raman and NMR measurements are demonstrated as useful tools to probe and determine phase behavior of thermomorphic ionic liquid-organic liquid systems. To illustrate the methods, consecutive conductivity measurements of a thermomorphic methoxyethoxyethyl...

  18. Phase Change Enthalpies and Entropies of Liquid Crystals

    National Research Council Canada - National Science Library

    Acree, William E; Chickos, James S

    2006-01-01

    .... A group additivity approach used to estimate total phase change entropies of organic molecules applied to 627 of these liquid crystals is found to significantly overestimate their total phase change entropies...

  19. A power-efficient and non-volatile programmable logic array based on phase change memory

    Science.gov (United States)

    Du, Yuan; Ye, Yong; Kang, Yong; Xia, Yangyang; Song, Zhitang; Chen, Bomy

    2016-10-01

    Recently, numerous efforts have been made on NVM-based Field Programmable Gate Arrays (FPGAs) because the emerging non-volatile memory (NVM) technologies have the advantages of lower leakage power and higher density than Static Random Access Memory (SRAM) technology. However, the cost and the scale of FPGAs are so high and large that they can't be applied in the consumer electronics field and Internet of Things (IoT). Due to the small scale and low cost, Programmable Logic Array (PLA) is an ideal option for these fields. However, up to now there are few researches on non-volatile PLA based on emerging NVMs. In this paper, a power-efficient non-volatile PLA based on Phase Change Memory (PCM) is proposed. The proposed non-volatile PLA architecture has been evaluated using the 40 nm Complementary Metal Oxide Semiconductor (CMOS) technology, and the simulation results show the correct functionality of the PLA. After the PLA reads the configuration bits from the non-volatile programmable elements (PEs), the power of the programmable elements can be OFF. Therefore, the standby power of the programmable elements is much smaller than that of the commonly SRAM-based PLAs. The simulation results also show that the total power of nvPLA is reduced by about 53.6% when the supply power of Programmable Element is OFF.

  20. Characterisation of volatile organic compounds in stemwood using solid-phase microextraction.

    Science.gov (United States)

    Wajs, A; Pranovich, A; Reunanen, M; Willför, S; Holmbom, B

    2006-01-01

    Solid-phase microextraction (SPME), hydrodistillation and dynamic headspace combined with GC and GC-MS were applied and compared for the analysis of volatile organic compounds (VOCs) from coniferous wood. The SPME conditions (type of fibre, size of wood sample, temperature and exposure time) were optimised, and more than 100 VOCs and semi-volatile compounds extracted and identified from the sapwood and heartwood of Norway spruce (Picea abies). The total number of mono- and sesquiterpenes eluted and identified was similar for the SPME and hydrodistillation methods, but more semi-volatile compounds were released by hydrodistillation. By applying dynamic headspace at room temperature, it was possible to analyse only the most volatile compounds. The qualitative composition of VOCs was similar in spruce sapwood and heartwood, although Z-beta-ocimene occurred only in sapwood while fenchol was present only in heartwood. SPME sampling coupled with GC, applied here to the analysis of VOCs released from stemwood of firs for the first time, is a convenient, sensitive, fast, solvent-free and simple method for the determination of wood volatiles. The technique requires much smaller sample amounts compared with hydrodistillation, and the total amount of VOCs extracted and identified is higher than that obtained by hydrodistillation or dynamic headspace. The relative ratios of the main mono- and sesquiterpenes and -terpenoids were similar using the SPME-GC and hydrodistillation methods.

  1. SELFIES, EMOJIS, LIKES: VOLATILE REPRESENTATIONS AND LIQUID READINGS IN THE DIGITAL AGE

    Directory of Open Access Journals (Sweden)

    Josiane da Cruz Lima Ribeiro

    2016-12-01

    Full Text Available This work aims at discussing the roles that hypermedia codes, such as selfies, emoji and likes, have played as representations and readings of self and other in the digital age, and how the school has behaved on this new outlook in dealing with volatile information and communication. The roads previously experienced by unilineal paths give way to the establishment of misshapen interconnective roads surrounding cyberspace and become unstable records of us and the reading we make of another person, constantly re-enacted by new records and, consequently, for new readings. Ubiquity, mediated mainly by mobile devices – mobile phones, smartphones and tablets –, provides this constant updating and metamorphoses, uninterruptedly, our representation in cyberspace. In this framework, the school is challenged to think about how to deal with these new perspectives of reading, since this is a reality brought by the student to the field of formal education. Therefore, we use the literature and took as a basis some theorists such as Santaella (2004; 2007; 2013, Hall (2006, Lévy (1994, Malini & Antoun (2013, among others, to bring to the discussion concepts of liquid identities, volatile representations, information and communication technologies and education.

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

    Science.gov (United States)

    Collins, E. R., Jr.

    1985-01-01

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

  3. Volatile Compounds Detected in Coconut Shell Liquid Smoke through Pyrolysis at a Fractioning Temperature of 350-420 C

    Directory of Open Access Journals (Sweden)

    Ruslin Hadanu

    2016-09-01

    Full Text Available This study evaluated the volatile components of liquid smoke from coconut shells obtained through the pyrolysis process at fraction 350-420 °C. The volatile compounds of liquid smoke from a coconut shell were analyzed using gas chromatography and mass spectrometry (GC-MS. Nineteen peaks were detected by GC-MS in the coconut shell liquid smoke, and 19 compounds also were identified. The volatile compounds were identified as follows based on their function group’s composition percentage: phenol (90.75%, carbonyl (3.71%, alcohol (1.81%, and benzene (3.73%, respectively. The liquid smoke contains a high ratio of phenol derivatives (90.75% in volatile profile. The phenol derivatives were the major volatile compounds found in the coconut shell liquid smoke.

  4. Groundwater cleanup by in-situ sparging. XIII. Random air channels for sparing of dissolved and nonaqueous phase volatiles

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, D.J.; Clarke, A.N. [Eckenfelder, Inc., Nashville, TN (United States); Kaminski, K.M.; Chang, E.Y. [Martin Luther King Magnet High School, Nashville, TN (United States)

    1997-12-01

    A mathematical model is developed to simulate the sparging of dissolved volatile organic compounds (VOCs) and nonaqueous phase liquid (NAPL) from contaminated aquifers. The sparging air moves through the aquifer in persistent, random channels, to which VOC must move by diffusion/dispersion to be removed. The dependence of the rate of remediation on the various model parameters is investigated and some practical conclusions are reached regarding the operation of air sparging wells for aquifer remediation. VOCs of low water solubility (such as alkanes) and present as NAPL are found to be removed by air sparging much more slowly than VOCs of higher water solubility (such as benzene, toluene, ethylbenzene and xylenes) and present as NAPL, due to the very small maximum concentration gradients which can be maintained around droplets of the former. These small concentration gradients result in very slow rates of NAPL solution.

  5. RESEARCH ON METHOD TO CALCULATE VELOCITIES OF SOLID PHASE AND LIQUID PHASE IN DEBRIS FLOW

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Velocities of solid phase and liquid phase in debris flow are one key problem to research on impact and abrasion mechanism of banks and control structures under action of debris flow. Debris flow was simplified as two-phase liquid composed of solid phase with the same diameter particles and liquid phase with the same mechanical features. Assume debris flow was one-dimension two-phase liquid moving to one direction,then general equations of velocities of solid phase and liquid phase were founded in twophase theory. Methods to calculate average pressures, volume forces and surface forces of debris flow control volume were established. Specially, surface forces were ascertained using Bingham's rheology equation of liquid phase and Bagnold's testing results about interaction between particles of solid phase. Proportional coefficient of velocities between liquid phase and solid phase was put forward, meanwhile, divergent coefficient between theoretical velocity and real velocity of solid phase was provided too. To state succinctly before, method to calculate velocities of solid phase and liquid phase was obtained through solution to general equations. The method is suitable for both viscous debris flow and thin debris flow. Additionally, velocities every phase can be identified through analyzing deposits in-situ after occurring of debris flow. It is obvious from engineering case the result in the method is consistent to that in real-time field observation.

  6. Supported Ionic Liquid Phase (SILP) catalysis

    DEFF Research Database (Denmark)

    Riisager, Anders; Fehrmann, Rasmus; Haumann, Marco;

    2006-01-01

    Applications of ionic liquids to replace conventional solvents in homogeneous transition-metal catalysis have increased significantly during the last decade. Biphasic ionic liquid/organic liquid systems offer advantages with regard to product separation, catalyst stability, and recycling but util...

  7. Simulation of phase separation in quiescent and sheared liquids

    NARCIS (Netherlands)

    Thakre, Amol Kumar

    2008-01-01

    In this thesis we report on molecular dynamics simulations of phase separation of simple and complex binary liquids in sheared and non-sheared systems. The separation of milk into liquid whey and solid curd is a very common example of phase separation observed in daily life. The phenomenon finds its

  8. Volatile profile of yellow passion fruit juice by static headspace and solid phase microextraction techniques

    Directory of Open Access Journals (Sweden)

    Gilberto Costa Braga

    2015-02-01

    Full Text Available The profile of volatile compounds of yellow passion fruit juice was analyzed by solid phase microextraction headspace (HS-SPME and optimized static headspace (S-HS extraction techniques. Time, temperature, NaCl concentration and sample volume headspace equilibrium parameters was adjusted to the S-HS technique. The gaseous phase in the headspace of samples was collected and injected into a gas chromatograph coupled to a mass spectrometer. In the HS-SPME technique was identified 44 volatile compounds from the yellow passion fruit juice, but with S-HS only 30 compounds were identified. Volatile esters were majority in both techniques, being identified ethyl butanoate, ethyl hexanoate, (3z-3-hexenyl acetate, hexyl acetate, hexyl butanoate and hexyl hexanoate. Aldehydes and ketones were not identified in S-HS, but were in HS-SPME. β-Pinene, p-cymene, limonene, (Z-β-ocimene, (E-β-ocimene, γ-terpinene, α-terpinolene and (E -4,8-dimethyl-1, 3,7 - nonatriene terpenes were identified in both techniques. This study showed that the S-HS optimized extraction technique was effective to recovery high concentrations of the major volatile characteristics compounds in the passion fruit, such as ethyl butanoate and ethyl hexanoate, which can be advantageous due to the simplicity of the method.

  9. Untargeted metabolomic analysis using liquid chromatography quadrupole time-of-flight mass spectrometry for non-volatile profiling of wines

    Energy Technology Data Exchange (ETDEWEB)

    Arbulu, M. [Department of Analytical Chemistry, Faculty of Pharmacy, University of the Basque Country, 01006 Vitoria-Gasteiz (Spain); Sampedro, M.C. [Central Service of Analysis, SGIker, University of the Basque Country, 01006 Vitoria-Gasteiz (Spain); Gómez-Caballero, A.; Goicolea, M.A. [Department of Analytical Chemistry, Faculty of Pharmacy, University of the Basque Country, 01006 Vitoria-Gasteiz (Spain); Barrio, R.J., E-mail: r.barrio@ehu.es [Department of Analytical Chemistry, Faculty of Pharmacy, University of the Basque Country, 01006 Vitoria-Gasteiz (Spain)

    2015-02-09

    Highlights: • An untargeted metabolomic method for the non-volatile profile of the Graciano wine was developed. • 411 different metabolites in Graciano Vitis vinifera red wine were identified. • 15 compounds could serve to differentiate Graciano and Tempranillo wines. • An enological database (WinMet) with 2080 compounds was constructed. - Abstract: The current study presents a method for comprehensive untargeted metabolomic fingerprinting of the non-volatile profile of the Graciano Vitis vinifera wine variety, using liquid chromatography/electrospray ionization time of flight mass spectrometry (LC–ESI-QTOF). Pre-treatment of samples, chromatographic columns, mobile phases, elution gradients and ionization sources, were evaluated for the extraction of the maximum number of metabolites in red wine. Putative compounds were extracted from the raw data using the extraction algorithm, molecular feature extractor (MFE). For the metabolite identification the WinMet database was designed based on electronic databases and literature research and includes only the putative metabolites reported to be present in oenological matrices. The results from WinMet were compared with those in the METLIN database to evaluate how much the databases overlap for performing identifications. The reproducibility of the analysis was assessed using manual processing following replicate injections of Vitis vinifera cv. Graciano wine spiked with external standards. In the present work, 411 different metabolites in Graciano Vitis vinifera red wine were identified, including primary wine metabolites such as sugars (4%), amino acids (23%), biogenic amines (4%), fatty acids (2%), and organic acids (32%) and secondary metabolites such as phenols (27%) and esters (8%). Significant differences between varieties Tempranillo and Graciano were related to the presence of fifteen specific compounds.

  10. OPTIMIZED DETERMINATION OF TRACE JET FUEL VOLATILE ORGANIC COMPOUNDS IN HUMAN BLOOD USING IN-FIELD LIQUID-LIQUID EXTRACTION WITH SUBSEQUENT LABORATORY GAS CHROMATOGRAPHIC-MASS SPECTROMETRIC ANALYSIS AND ON-COLUMN LARGE VOLUME INJECTION

    Science.gov (United States)

    A practical and sensitive method to assess volatile organic compounds (VOCs) from JP-8 jet fuel in human whole blood was developed by modifying previously established liquid-liquid extraction procedures, optimizing extraction times, solvent volume, specific sample processing te...

  11. Improvement for the steering performance of liquid crystal phased array

    Institute of Scientific and Technical Information of China (English)

    SONG Yan; KONG Ling-jiang; CHEN Jun; ZHU Ying; YANG Jian-yu

    2009-01-01

    Optical phased array technology is introduced and the steering performances of liquid crystal phased array are discussed, several factors affecting the beam steering performances arc analyzed completely, also simple models for some typical factors are developed. Then, a new method based on iterating and modifying the output phase pattern of liquid crystal phase shifters is proposed. Using this method, the modified voltages applied on electrodes of liquid crystal phase shifters can be obtained, after applying the voltages, the influence of factors can be compensated to some extent; the steering angle accu-racy and efficiency with liquid crystal phased array can be improved. Through the simulation for the angle range from 0° to -1°, the error of steering angle can be reduced three orders of magnitude, and the efficiency can be increased almost 30% after several iterations.

  12. Application of head-space solid-phase microextraction for the analysis of volatile metabolites emitted by Penicillium species

    DEFF Research Database (Denmark)

    Nilsson, Torben; Larsen, Thomas Ostenfeld; Montanarella, Luca

    1996-01-01

    Head-space solid-phase microextraction (HS-SPME) has been used to collect volatile organic compounds (VOCs) emitted from fungi of the genus Penicillium. Gas chromatography combined with mass spectrometry (GC-MS) was employed for the analysis of the profiles of volatile metabolites characteristic ...

  13. Effect of counter current gas phase on liquid film

    Institute of Scientific and Technical Information of China (English)

    Shujuan LUO; Huaizhi LI; Weiyang FEI; Yundong WANG

    2009-01-01

    Liquid film flow is very important in many industrial applications. However, there are few reports about its characteristics on structured packings. Therefore, in this paper, liquid film phenomena were investigated experimentally to exploit new approaches for intensifying the performance of the structured packings. All experiments were performed at room temperature. Water and air were the working fluids. The effect of counter current gas phase on the liquid film was taken into consideration. A high speed camera, a non-intrusive measurement technique, was used. It is shown that both liquid and gas phases have strong effects on film characteristics. In the present work, liquid film width increased by 57% because of increasing liquid flow rate, while it decreased by 25% resulting from the counter current gas phase.

  14. Evaluation of the particle measurement programme (PMP) protocol to remove the vehicles' exhaust aerosol volatile phase.

    Science.gov (United States)

    Giechaskiel, B; Chirico, R; Decarlo, P F; Clairotte, M; Adam, T; Martini, G; Heringa, M F; Richter, R; Prevot, A S H; Baltensperger, U; Astorga, C

    2010-10-01

    European regulation for Euro 5/6 light duty emissions introduced the measurement of non-volatile particles with diameter >23 nm. The volatile phase is removed by using a heated dilution stage (150 degrees C) and a heated tube (at 300-400 degrees C). We investigated experimentally the removal efficiency for volatile species of the specific protocol by conducting measurements with two Euro 3 diesel light duty vehicles, a Euro 2 moped, and a Euro III heavy duty vehicle with the system's heaters on and off. The particle number distributions were measured with a Scanning Mobility Particle Sizer (SMPS) and a Fast Mobility Particle Sizer (FMPS). An Aerosol Mass Spectrometer (AMS) was used to identify the non-refractory chemical composition of the particles. A Multi-Angle Absorption Photometer (MAAP) was used to measure the black carbon concentration. The results showed that the condensed material in the accumulation mode (defined here as particles in the diameter range of approximately 50-500 nm) was removed with an efficiency of 50-90%. The (volatile) nucleation mode was also completely evaporated or was decreased to sizes <23 nm; thus these particles wouldn't be counted from the particle counter, indicating the robustness of the protocol.

  15. Analysis of solid-liquid phase change heat transfer enhancement

    Institute of Scientific and Technical Information of China (English)

    张寅平; 王馨

    2002-01-01

    Solid-liquid phase change processes have two important features: the process is an approximately isothermal process and the heat of fusion of phase change material tends to be much greater than its specific heat. Therefore, if any phase change material adjacent to a hot or cold surface undergoes phase change, the heat transfer rate on the surface will be noticeably enhanced. This paper presents a novel insight into the mechanisms of heat transfer enhancement induced by solid-liquid phase change based on the analogy analysis for heat conduction with an internal heat source and solid-liquid phase change heat transfer. Three degrees of surface heat transfer enhancement for different conditions are explored, and corresponding formulae are written to describe them. The factors influencing the degrees of heat transfer enhancement are clarified and their effects quantitatively analyzed. Both the novel insight and the analysis contribute to effective application of phase change heat transfer enhancement technique.

  16. Thermal stability analysis of the liquid phase methanol synthesis reactor

    Energy Technology Data Exchange (ETDEWEB)

    Gogate, M.R.; Desirazu, S.; Berty, J.M.; Lee, S. (Akron University, Akron, OH (USA). Dept. of Chemical Engineering)

    1992-01-01

    The effect of addition of an inert liquid phase on the rate of heat generation in the catalytic synthesis of methanol from syngas has been studied. Gas compositions typical of product gases from Lurgi and Koppers-Totzek gasifiers, represented by H[sub 2]-rich and CO-rich syngas respectively, were used to experimentally verify the 'slope' and 'dynamic' criteria in a three-phase fixed bed recycle reactor. The liquid medium, Witco-40 oil, has been effective in controlling the rate of heat generation and in preventing catalyst overheating, signifying that the liquid phase synthesis is thermally far more stable than the vapour phase synthesis. The experimental thermal stability study provides crucial and valuable information in commercializing the liquid phase methanol synthesis process. The current approach of thermal stability analysis does not require any a priori assumption or predetermined reaction kinetics. 22 refs., 6 figs., 7 tabs.

  17. Liquid-Gas Phase Transition in Nuclear Equation of State

    CERN Document Server

    Lee, S J

    1997-01-01

    A canonical ensemble model is used to describe a caloric curve of nuclear liquid-gas phase transition. Allowing a discontinuity in the freeze out density from one spinodal density to another for a given initial temperature, the nuclear liquid-gas phase transition can be described as first order. Averaging over various freeze out densities of all the possible initial temperatures for a given total reaction energy, the first order characteristics of liquid-gas phase transition is smeared out to a smooth transition. Two experiments, one at low beam energy and one at high beam energy show different caloric behaviors and are discussed.

  18. Liquid-liquid transition without macroscopic phase separation in a water-glycerol mixture

    Science.gov (United States)

    Murata, Ken-Ichiro; Tanaka, Hajime

    2012-05-01

    The existence of more than two liquid states in a single-component substance and the ensuing liquid-liquid transitions (LLTs) has attracted considerable attention because of its counterintuitive nature and its importance in the fundamental understanding of the liquid state. Here we report direct experimental evidence for a genuine (isocompositional) LLT without macroscopic phase separation in an aqueous solution of glycerol. We show that liquid I transforms into liquid II by way of two types of kinetics: nucleation and growth, and spinodal decomposition. Although liquid II is metastable against crystallization, we could access both its static and dynamical properties experimentally. We find that liquids I and II differ in density, refractive index, structure, hydrogen bonding state, glass transition temperature and fragility, and that the transition between the two liquids is mainly driven by the local structuring of water rather than of glycerol, suggesting a link to a plausible LLT inpure water.

  19. Two Coexisting Liquid Phases in Switchable Ionic Liquids

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Juan; Lao, David; Sui, Xiao; Zhou, Yufan; Nune, Satish K.; Ma, Xiang; Troy, Tyler; Ahmed, Musahid; Zhu, Zihua; Heldebrant, David J.; Yu, Xiao-Ying

    2017-08-30

    In situ time-of-flight secondary ion mass spectrometry (ToF-SIMS) coupled with a vacuum compatible microfluidic reactor, System for Analysis at Liquid Vacuum Interface (SALVI), has enabled the first spatial mapping of the switchable ionic liquids (SWILs) derived from 1,8-diazabicycloundec-7-ene (DBU) and 1-hexanol. As predicted by molecular dynamic simulations, our molecular imaging results confirmed a dynamic heterogeneous molecular structure with ionic regions (high CO2 concentration) coexisting with non-ionic regions (no CO2) where stoichiometry would indicate otherwise. Chemical speciation was also found to be more complex than initially thought, with spectral principal component analysis identifying dimers that ultimately highlight a highly complex molecular structure unique to SWILs. The spatial chemical mapping enabled by ToF-SIMS and SALVI advances the understanding of how the heterogeneous molecular structure impacts the dynamic physical and thermodynamic properties or SWILs.

  20. Thermomorphic phase separation in ionic liquid-organic liquid systems--conductivity and spectroscopic characterization.

    Science.gov (United States)

    Riisager, Anders; Fehrmann, Rasmus; Berg, Rolf W; van Hal, Roy; Wasserscheid, Peter

    2005-08-21

    Electrical conductivity, FT-Raman and NMR measurements are demonstrated as useful tools to probe and determine phase behavior of thermomorphic ionic liquid-organic liquid systems. To illustrate the methods, consecutive conductivity measurements of a thermomorphic methoxyethoxyethyl-imidazolium ionic liquid/1-hexanol system are performed in the temperature interval 25-80 degrees C using a specially constructed double-electrode cell. In addition, FT-Raman and 1H-NMR spectroscopic studies performed on the phase-separable system in the same temperature interval confirm the mutual solubility of the components in the system, the liquid-liquid equilibrium phase diagram of the binary mixture, and signify the importance of hydrogen bonding between the ionic liquid and the hydroxyl group of the alcohol.

  1. Ionic Liquids as Mobile Phase Additives for Separation of Nucleotides in High-Performance Liquid Chromatography

    Institute of Scientific and Technical Information of China (English)

    ZHANG,Wen-Zhu(张文珠); HE,Li-Jun(何丽君); LIU,Xia(刘霞); JIANG,Sheng-Xiang(蒋生祥)

    2004-01-01

    Ionic liquids are a type of salts that are liquid at low temperature (< 100 ℃). Because of their some special properties, they have been widely used as new "green solvents" for many chemical reactions and liquid-liquid extraction in the past several years. In this paper, a new method for the separation of nucleotides is developed and the essential feature of the method is that 1-alkyl-3-methylimidazolium salts are used as mobile phase additives, resulting in a baseline separation of nucleotides without need of gradient elution and need of organic solvent addition as currently used in RP-HPLC. This study shows the potential application of ionic liquids as mobile phase additives in reversed-phase liquid chromatography.

  2. CATION-EXCHANGE SOLID-PHASE AND LIQUID-LIQUID ...

    African Journals Online (AJOL)

    B. S. Chandravanshi

    cation exchange-solid phase extraction (SCX-SPE) was investigated as an .... Stock solutions, with a concentration of 1.00 mg/mL were prepared ... Johannesburg, South Africa) connected to a vacuum pump (Vacuubrand, GMBH, Germany).

  3. Discharge characteristics of an ablative pulsed plasma thruster with non-volatile liquid propellant

    Science.gov (United States)

    Ling, William Yeong Liang; Schönherr, Tony; Koizumi, Hiroyuki

    2017-07-01

    Pulsed plasma thrusters (PPTs) are a form of electric spacecraft propulsion. They have an extremely simple structure and are highly suitable for nano/micro-spacecraft with weights in the kilogram range. Such small spacecraft have recently experienced increased growth but still lack suitable efficient propulsion systems. PPTs operate in a pulsed mode (one discharge = one shot) and typically use solid polytetrafluoroethylene (PTFE) as a propellant. However, new non-volatile liquids in the perfluoropolyether (PFPE) family have recently been found to be promising alternatives. A recent study presented results on the physical characteristics of PFPE vs. PTFE, showing that PFPE is superior in terms of physical characteristics such as its resistance to carbon deposition. This letter will examine the electrical discharge characteristics of PFPE vs. PTFE. The results demonstrate that PFPE has excellent shot-to-shot repeatability and a lower discharge resistance when compared with PTFE. Taken together with its physical characteristics, PFPE appears to be a strong contender to PTFE as a PPT propellant.

  4. Selection of ionic liquids for enhancing the gas solubility of volatile organic compounds.

    Science.gov (United States)

    Gonzalez-Miquel, Maria; Palomar, Jose; Rodriguez, Francisco

    2013-01-10

    A systematic thermodynamic analysis has been carried out for selecting cations and anions to enhance the absorption of volatile organic compounds (VOCs) at low concentration in gaseous streams by ionic liquids (ILs), using COSMO-RS methodology. The predictability of computational procedure was validated by comparing experimental and COSMO-RS calculated Henry's law constant data over a sample of 125 gaseous solute-IL systems. For more than 2400 solute-IL mixtures evaluated, including 9 solutes and 270 ILs, it was found that the lower the activity coefficient at infinite dilution (γ(∞)) of solutes in the ILs, the more the exothermic excess enthalpy (H(E)) of the equimolar IL-solute mixtures. Then, the solubility of a representative sample of VOC solutes, with very different chemical nature, was screened in a wide number of ILs using COSMO-RS methodology by means of γ(∞) and H(E) parameters, establishing criteria to select the IL structures that promote favorable solute-solvent intermolecular interactions. As a result of this analysis, an attempt of classification of VOCs respect to their potential solubility in ILs was proposed, providing insights to rationally select the cationic and anionic species for a possible development of absorption treatments of VOC pollutants based on IL systems.

  5. Stability of a volatile liquid film spreading along a heterogeneously-heated substrate.

    Science.gov (United States)

    Tiwari, Naveen; Davis, Jeffrey M

    2011-03-01

    The dynamics and stability of a thin, viscous film of volatile liquid flowing under the influence of gravity over a non-uniformly heated substrate are investigated using lubrication theory. Attention is focused on the regime in which evaporation balances the flow due to gravity. The film terminates above the heater at an apparent contact line, with a microscopically thin precursor film adsorbed due to the disjoining pressure. The film develops a weak thermocapillary ridge due to the Marangoni stress at the upstream edge of the heated region. As for spreading films, a more significant ridge is formed near the apparent contact line. For weak Marangoni effects, the film evolves to a steady profile. For stronger Marangoni effects, the film evolves to a time-periodic state. Results of a linear stability analysis reveal that the steady film is unstable to transverse perturbations above a critical value of the Marangoni parameter, leading to finger formation at the contact line. The streamwise extent of the fingers is limited by evaporation. The time-periodic profiles are always unstable, leading to the formation of periodically-oscillating fingers. For rectangular heaters, the film profiles after instability onset are consistent with images from published experimental studies.

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

    Energy Technology Data Exchange (ETDEWEB)

    John Crepeau; Ali s. Siahpush

    2012-07-01

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

  7. Statistical nature of cluster emission in nuclear liquid phase

    OpenAIRE

    Ma, Y.G.

    2002-01-01

    The emission of nuclear clusters is investigated within the framework of isospin dependent lattice gas model and classical molecular dynamics model. It is found that the emission of individual cluster which is heavier than proton is almost Poissonian except near the liquid gas phase transition point and the thermal scaling is observed by the linear Arrhenius plots which is made from the average multiplicity of each cluster versus the inverse of temperature in the nuclear liquid phase. It indi...

  8. Axial dispersion of the liquid phase in a three-phase Karr reciprocating plate column

    Directory of Open Access Journals (Sweden)

    DEJAN U. SKALA

    2004-07-01

    Full Text Available The influence of the gas flow rate and vibration intensity in the presence of the solid phase (polypropylene spheres on axial mixing of the liquid phase in a three phase (gas-liquid-solid Karr reciprocating plate column (RPC was investigated. Assuming that the dispersion model of liquid flow could be used for the real situation inside the column, the dispersion coefficient of the liquid phase was determined as a function of different operating parameters. For a two-phase liquid-solid RPC the following correlation was derived: DL = 1.26(Af1.42 UL0.51 eS0.23 and a similar equation could be applied with ± 30 % confidence for the calculation of axial dispersion in the case of a three-phase RPC: DL = 1.30(Af0.47 UL0.42 UG0.03eS-0.23.

  9. Phase partitioning and volatility of secondary organic aerosol components formed from α-pinene ozonolysis and OH oxidation: the importance of accretion products and other low volatility compounds

    Directory of Open Access Journals (Sweden)

    F. D. Lopez-Hilfiker

    2015-02-01

    Full Text Available We measured a large suite of gas and particle phase multi-functional organic compounds with a Filter Inlet for Gases and AEROsols (FIGAERO coupled to a high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS developed at the University of Washington. The instrument was deployed on environmental simulation chambers to study monoterpene oxidation as a secondary organic aerosol (SOA source. We focus here on results from experiments utilizing an ionization method most selective towards acids (acetate negative ion proton transfer, but our conclusions are based on more general physical and chemical properties of the SOA. Hundreds of compounds were observed in both gas and particle phases, the latter being detected upon temperature programmed thermal desorption of collected particles. Particulate organic compounds detected by the FIGAERO HR-ToF-CIMS are highly correlated with, and explain at least 25–50% of, the organic aerosol mass measured by an Aerodyne Aerosol Mass Spectrometer (AMS. Reproducible multi-modal structures in the thermograms for individual compounds of a given elemental composition reveal a significant SOA mass contribution from large molecular weight organics and/or oligomers (i.e. multi-phase accretion reaction products. Approximately 50% of the HR-ToF-CIMS particle phase mass is associated with compounds having effective vapor pressures 4 or more orders of magnitude lower than commonly measured monoterpene oxidation products. The relative importance of these accretion-type and other extremely low volatility products appears to vary with photochemical conditions. We present a desorption temperature based framework for apportionment of thermogram signals into volatility bins. The volatility-based apportionment greatly improves agreement between measured and modeled gas–particle partitioning for select major and minor components of the SOA, consistent with thermal decomposition during desorption causing

  10. INFLUENCE OF INVESTORS’ ATTENTION ON STOCK RETURN, LIQUIDITY, AND RETURN VOLATILITY COMPARISON BETWEEN MANUFACTURE COMPANIES IN INDONESIA AND INDIA

    OpenAIRE

    Puspita Sari, Noviana Icha

    2014-01-01

    This research aims to examine the influence of investors’ attention of company stock on stock return, liquidity, and return volatility comparison between manufacture companies in Indonesia and India in the year of 2011-2013. Investors’ attention is measured by a direct proxy which is Google Search Volume Index from Google trends. This research uses secondary data and processed by regression analysis. The samples are gathered from Indonesia stock exchange and India stock exchange. The result o...

  11. Gas-Liquid Flows and Phase Separation

    Science.gov (United States)

    McQuillen, John

    2004-01-01

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

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

    Science.gov (United States)

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

    2016-05-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Limei [Center for Polymer Studies and Department of Physics, Boston University, Boston, MA 02215 (United States); Ehrenberg, Isaac [Department of Physics, Yeshiva University, 500 West 185th Street, New York, NY 10033 (United States); Buldyrev, Sergey V [Center for Polymer Studies and Department of Physics, Boston University, Boston, MA 02215 (United States); Stanley, H Eugene [Center for Polymer Studies and Department of Physics, Boston University, Boston, MA 02215 (United States)

    2006-09-13

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

  14. The liquid to vapor phase transition in excited nuclei

    Energy Technology Data Exchange (ETDEWEB)

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

    2001-05-08

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

  15. The liquid to vapor phase transition in excited nuclei

    CERN Document Server

    Elliott, J B; Phair, L; Wozniak, G J; Lefort, T; Beaulieu, L; Kwiatkowski, K K; Hsi, W C; Pienkowski, L; Breuer, H; Korteling, R G; Laforest, R; Martin, E; Ramakrishnan, E; Rowland, D; Ruangma, A; Viola, V E; Winchester, E M; Yennello, S J

    2002-01-01

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

  16. Headspace Solid-Phase Microextraction Analysis of Volatile Components in Narcissus tazetta var. chinensis Roem

    Directory of Open Access Journals (Sweden)

    Hai-Shan Chi

    2013-11-01

    Full Text Available The volatile components in single-flowered and double-flowered Chinese narcissus were identified by headspace-solid phase microextraction (HS-SPME coupled with GC and GC/MS. Changes in aroma during the vase-life (days 0, 1, 2, 3, 4, 5 and 6 of two samples were also studied. A total of 35 compounds were identified, of which all were present in single-flowered and 26 in double-flowered samples. The main aroma components were (E-β-ocimene, and benzyl acetate. Single-flowered narcissus have a higher percentage of benzyl acetate, while double-flowered narcissus have a higher percentage of 1,8-cineole. In vase-life, the total volatile component content peaked on day 2 for single-flowered and day 3 for the double-flowered narcissus. For both single-flowered and double-flowered narcissus flowers, the total content of volatile components had decreased significantly by day 4.

  17. Volatile composition of peppermint (Mentha piperita L.) commercial teas through solid phase extraction.

    Science.gov (United States)

    Riachi, L G; Abi-Zaid, I E; Moreira, R F A; De Maria, C A B

    2012-12-01

    Volatiles from aqueous extract of peppermint commercial sachets were investigated through gas chromatography/flame ionization detection (GC/FID) and GC/mass spectrometry (MS). Samples were prepared under similar conditions as in homemade tea. Volatiles were isolated using solid phase extraction method (SPE) with Porapak Q trap followed by desorption with acetone. Estimated mean values for short and medium chain carboxylic acids (C2-C12) and ketones lay in the range of 50-64 microg kg(-1) whilst aliphatic alcohols and acyclic hydrocarbons had values lower than 6 microg kg(-1). The major volatiles were terpenes (275-382 microg kg(-1)) that reached 89 % of the total composition. A total of 16 compounds, among them dodecane, acetoin, acetol, citral, geraniol and octanoic acid have been described by the first time in peppermint tea. These findings could be attributed to the different analytical approach employed, mainly to the use of different extraction/pre-concentration techniques. Given the apparently lower proportion of terpenes in the aqueous extract it may be that the chemical properties of the peppermint essential oil are not entirely reproduced with homemade tea.

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

    CERN Document Server

    Ma, Xiaoguang

    2012-01-01

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

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

    Science.gov (United States)

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

    2014-02-01

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

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

    Science.gov (United States)

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

    2011-12-07

    The current state-of-the-art for hydrogen storage is compressed H(2) at 700 bar. The development of a liquid-phase hydrogen storage material has the potential to take advantage of the existing liquid-based distribution infrastructure. We describe a liquid-phase hydrogen storage material that is a liquid under ambient conditions (i.e., at 20 °C and 1 atm pressure), air- and moisture-stable, and recyclable; releases H(2) controllably and cleanly at temperatures below or at the proton exchange membrane fuel cell waste-heat temperature of 80 °C; utilizes catalysts that are cheap and abundant for H(2) desorption; features reasonable gravimetric and volumetric storage capacity; and does not undergo a phase change upon H(2) desorption. © 2011 American Chemical Society

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

    Directory of Open Access Journals (Sweden)

    Nicolas Giovambattista

    2010-12-01

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

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

    Science.gov (United States)

    Ushenko, Yu. A.; Sidor, M.

    2013-06-01

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

  3. Nuclear Liquid-Gas Phase Transition: Experimental Signals

    Science.gov (United States)

    D'Agostino, M.; Bruno, M.; Gulminelli, F.; Cannata, F.; Chomaz, Ph.; Casini, G.; Geraci, E.; Gramegna, F.; Moroni, A.; Vannini, G.

    2005-03-01

    The connection between the thermodynamics of charged finite nuclear systems and the asymptotically measured partitions in heavy ion collisions is discussed. Different independent signals compatible with a liquid-to-gas-like phase transition are reported. In particular abnormally large fluctuations in the measured observables are presented as a strong evidence of a first order phase transition with negative heat capacity.

  4. Nuclear liquid-gas phase transition: Experimental signals

    Energy Technology Data Exchange (ETDEWEB)

    D' Agostino, M. [Dipartimento di Fisica and INFN, Bologna (Italy); Bruno, M. [Dipartimento di Fisica and INFN, Bologna (Italy); Gulminelli, F. [LPC Caen (IN2P3-CNRS/ISMRA et Universite), F-14050 Caen Cedex (France); Cannata, F. [Dipartimento di Fisica and INFN, Bologna (Italy); Chomaz, Ph. [GANIL, DSM-CEA/IN2P3-CNRS (France); Casini, G. [INFN Sezione di Firenze (Italy); Geraci, E. [Dipartimento di Fisica and INFN, Bologna (Italy); Gramegna, F. [INFN Laboratorio Nazionale di Legnaro (Italy); Moroni, A. [Dipartimento di Fisica and INFN, Milano (Italy); Vannini, G. [Dipartimento di Fisica and INFN, Bologna (Italy)

    2005-03-07

    The connection between the thermodynamics of charged finite nuclear systems and the asymptotically measured partitions in heavy ion collisions is discussed. Different independent signals compatible with a liquid-to-gas-like phase transition are reported. In particular abnormally large fluctuations in the measured observables are presented as a strong evidence of a first order phase transition with negative heat capacity.

  5. Entropy calculations for a supercooled liquid crystalline blue phase

    Energy Technology Data Exchange (ETDEWEB)

    Singh, U [Physics Department, University of the West Indies, PO Box 64, Bridgetown (Barbados)

    2007-01-15

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

  6. Thermomorphic phase separation in ionic liquid-organic liquid systems - conductivity and spectroscopic characterization

    DEFF Research Database (Denmark)

    Riisager, Anders; Fehrmann, Rasmus; Berg, Rolf W.

    2005-01-01

    Electrical conductivity, FT-Raman and NMR measurements are demonstrated as useful tools to probe and determine phase behavior of thermomorphic ionic liquid-organic liquid systems. To illustrate the methods, consecutive conductivity measurements of a thermomorphic methoxyethoxyethyl-imidazolium io...... of the components in the system, the liquid-liquid equilibrium phase diagram of the binary mixture, and signify the importance of hydrogen bonding between the ionic liquid and the hydroxyl group of the alcohol.......Electrical conductivity, FT-Raman and NMR measurements are demonstrated as useful tools to probe and determine phase behavior of thermomorphic ionic liquid-organic liquid systems. To illustrate the methods, consecutive conductivity measurements of a thermomorphic methoxyethoxyethyl......-imidazolium ionic liquid/1-hexanol system are performed in the temperature interval 25-80 degrees C using a specially constructed double-electrode cell. In addition, FT-Raman and H-1-NMR spectroscopic studies performed on the phase-separable system in the same temperature interval confirm the mutual solubility...

  7. All-soft, battery-free, and wireless chemical sensing platform based on liquid metal for liquid- and gas-phase VOC detection.

    Science.gov (United States)

    Kim, Min-Gu; Alrowais, Hommood; Kim, Choongsoon; Yeon, Pyungwoo; Ghovanloo, Maysam; Brand, Oliver

    2017-06-27

    Lightweight, flexible, stretchable, and wireless sensing platforms have gained significant attention for personal healthcare and environmental monitoring applications. This paper introduces an all-soft (flexible and stretchable), battery-free, and wireless chemical microsystem using gallium-based liquid metal (eutectic gallium-indium alloy, EGaIn) and poly(dimethylsiloxane) (PDMS), fabricated using an advanced liquid metal thin-line patterning technique based on soft lithography. Considering its flexible, stretchable, and lightweight characteristics, the proposed sensing platform is well suited for wearable sensing applications either on the skin or on clothing. Using the microfluidic sensing platform, detection of liquid-phase and gas-phase volatile organic compounds (VOC) is demonstrated using the same design, which gives an opportunity to have the sensor operate under different working conditions and environments. In the case of liquid-phase chemical sensing, the wireless sensing performance and microfluidic capacitance tunability for different dielectric liquids are evaluated using analytical, numerical, and experimental approaches. In the case of gas-phase chemical sensing, PDMS is used both as a substrate and a sensing material. The gas sensing performance is evaluated and compared to a silicon-based, solid-state gas sensor with a PDMS sensing film.

  8. Prediction and experimental validation of liquid-phase diffusion resistance in unsaturated soils

    Science.gov (United States)

    Schaefer, C. E.; Arands, R. R.; van der Sloot, H. A.; Kosson, D. S.

    1995-11-01

    Determination of liquid-phase diffusion through unsaturated soils is important for estimating contaminant transport in soils and design of remediation processes for contaminated soils and groundwater. Liquid-phase diffusion through unsaturated soils is governed by both the pore size distribution and water distribution of the soil matrix. Diffusion tube experiments were carried out using several soils packed to field densities to determine the effective diffusivity of chloride ion as a function of soil moisture content. Chloride was selected to serve as a non-volatile, non-sorbing tracer species. A transport model was developed to predict liquid-phase tortuosity as a function of readily obtained soil parameters, including density, moisture content, particle size distribution and pore size distribution. The basis of the model was parallel diffusion resistances in the inter- and intra-particle pore regimes. The new model was found to provide an accurate prediction of observed experimental results. Previously reported models did not agree with experimental results over significant portions of the experimental domain investigated.

  9. Optimization of dynamic headspace extraction system for measurement of halogenated volatile organic compounds in liquid or viscous samples

    Science.gov (United States)

    Taniai, G.; Oda, H.; Kurihara, M.; Hashimoto, S.

    2010-12-01

    Halogenated volatile organic compounds (HVOCs) produced in the marine environment are thought to play a key role in atmospheric reactions, particularly those involved in the global radiation budget and the depression of tropospheric and stratospheric ozone. To evaluate HVOCs concentrations in the various natural samples, we developed an automated dynamic headspace extraction method for the determination of 15 HVOCs, such as chloromethane, bromomethane, bromoethane, iodomethane, iodoethane, bromochloromethane, 1-iodopropane, 2-iodopropane, dibromomethane, bromodichloromethane, chloroiodomethane, chlorodibromomethane, bromoiodomethane, tribromomethane, and diiodomethane. Dynamic headspace system (GERSTEL DHS) was used to purge the gas phase above samples and to trap HVOCs on the adsorbent column from the purge gas. We measured the HVOCs concentrations in the adsorbent column with gas chromatograph (Agilent 6890N)- mass spectrometer (Agilent 5975C). In dynamic headspace system, an glass tube containing Tenax TA or Tenax GR was used as adsorbent column for the collection of 15 HVOCs. The parameters for purge and trap extraction, such as purge flow rate (ml/min), purge volume (ml), incubation time (min), and agitator speed (rpm), were optimized. The detection limits of HVOCs in water samples were 1270 pM (chloromethane), 103 pM (bromomethane), 42.1 pM (iodomethane), and 1.4 to 10.2 pM (other HVOCs). The repeatability (relative standard deviation) for 15 HVOCs were < 9 % except chloromethane (16.2 %) and bromomethane (11.0 %). On the basis of the measurements for various samples, we concluded that this analytical method is useful for the determination of wide range of HVOCs with boiling points between - 24°C (chloromethane) and 181°C (diiodomethane) for the liquid or viscous samples.

  10. A superconductor to superfluid phase transition in liquid metallic hydrogen.

    Science.gov (United States)

    Babaev, Egor; Sudbø, Asle; Ashcroft, N W

    2004-10-07

    Although hydrogen is the simplest of atoms, it does not form the simplest of solids or liquids. Quantum effects in these phases are considerable (a consequence of the light proton mass) and they have a demonstrable and often puzzling influence on many physical properties, including spatial order. To date, the structure of dense hydrogen remains experimentally elusive. Recent studies of the melting curve of hydrogen indicate that at high (but experimentally accessible) pressures, compressed hydrogen will adopt a liquid state, even at low temperatures. In reaching this phase, hydrogen is also projected to pass through an insulator-to-metal transition. This raises the possibility of new state of matter: a near ground-state liquid metal, and its ordered states in the quantum domain. Ordered quantum fluids are traditionally categorized as superconductors or superfluids; these respective systems feature dissipationless electrical currents or mass flow. Here we report a topological analysis of the projected phase of liquid metallic hydrogen, finding that it may represent a new type of ordered quantum fluid. Specifically, we show that liquid metallic hydrogen cannot be categorized exclusively as a superconductor or superfluid. We predict that, in the presence of a magnetic field, liquid metallic hydrogen will exhibit several phase transitions to ordered states, ranging from superconductors to superfluids.

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

    Science.gov (United States)

    Qin, Sanbo; Zhou, Huan-Xiang

    2016-08-25

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

  12. Self-aggregation of vapor-liquid phase transition

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The concept of the molecular free path is introduced to derive a criterion distinguishing active molecules from inactive molecules in liquid phase. Based on molecular self-aggregation theory a concept of the critical aggregation concentration (CAC) of active molecules is proposed to describe the physical configuration before the formation of the nuclei in the process of vapor-liquid phase transition. All active molecules exist in the form of the monomer when the concentration of active molecules is lower than CAC, while the active molecules will generate aggregation once the concentration of the active molecules reaches CAC. However, these aggregates with the aggregation number N smaller than 5 can steadily exist in bulk phase. The other excess active molecules can only produce infinite aggregation and form a critical nucleus of vapor-liquid phase transition. Without outer perturbation the state point of CAC corresponds to the critical superheated or supercooled state in the process of vapor-liquid phase transition. With the aggregate property, the interfacial tension between the bulk phase and the tiny new phase is predicted and a correction is made for the classical nucleation rate in a quite good agreement with experimental results.

  13. Volatile heavy metal mobility in silicate liquids: Implications for volcanic degassing and eruption prediction

    Science.gov (United States)

    MacKenzie, Jason M.; Canil, Dante

    2008-05-01

    The volatilization of Cd, Re, Tl, Pb, Sb and Te from melts in the system CaO-MgO-Al 2O 3-SiO 2 (CMAS) and Na 2O-MgO-Al 2O 3-SiO 2 (NMAS) has been investigated at 0.1 MPa and 1200-1350 °C. Experiments were conducted in air using metal-doped melts in Pt crucibles. Analysis of quenched glasses by Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) normal to the melt/gas interface produced concentration profiles for Cd, Re, Tl, Pb, Sb and Te to which a semi-infinite one-dimensional diffusion model could be applied to extract diffusion coefficients ( D). The melt was also doped with Cu, Zn, In, Mo, Sn and W but concentration profiles for these metals did not develop. In the CMAS composition at 1300 °C, the fastest diffusing element was Cd having a log DCd = - 6.5 ± 0.2. The slowest element was Re with log DRe = - 7.5 ± 0.3. Diffusivities of Sb, Te, Pb and Tl have intermediate values where log DSb = - 7.1 ± 0.1, log DTe = - 7.2 ± 0.3, log DPb = - 7.1 ± 0.2, log DTl = - 7.0 ± 0.2 cm 2/s. In the NMAS composition, log DRe = - 6.5 ± 0.2, log DSb = - 6.0 ± 0.2, log DPb = - 6.1 ± 0.1, log DTl = - 5.8 ± 0.2 cm 2/s (values for Cd and Te were not determined). Differences in diffusivity of volatile heavy metal ions to a melt-gas interface lead to significant fractionation between these metals in magmas during degassing. Given the observed differences in Cd and Re diffusivities in the CMAS composition, we predict an increase in the normalized Cd/Re ratio in the gas phase with increasing bubble growth rate. Monitoring of the Cd/Re ratios in aerosols from degassing volcanoes may provide a tool for predicting volcanic eruption.

  14. Methods of liquid phase microextraction for the determination of cadmium in environmental samples.

    Science.gov (United States)

    Pires Santos, Analú; das Graças Andrade Korn, Maria; Azevedo Lemos, Valfredo

    2017-08-09

    Liquid phase microextraction (LPME) has been widely used in extraction and preconcentration systems as an excellent alternative to conventional liquid phase extraction. In this work, a critical review is presented on liquid phase microextraction techniques used in the determination of cadmium in environmental samples. LPME techniques are classified into three main groups: single-drop liquid phase microextraction (SDME), hollow fiber liquid phase microextraction (HF-LPME), and dispersive liquid-liquid microextraction (DLLME). Methods involving these liquid phase microextraction techniques are described, addressing advantages and disadvantages, samples, figures of merit, and trends.

  15. Use of headspace mulberry paper bag micro solid phase extraction for characterization of volatile aromas of essential oils from Bulgarian rose and Provence lavender.

    Science.gov (United States)

    Won, Mi-Mi; Cha, Eun-Ju; Yoon, Ok-Kyung; Kim, Nam-Sun; Kim, Kun; Lee, Dong-Sun

    2009-01-05

    In this study, a new sampling method called headspace mulberry paper bag micro solid phase extraction (HS-MPB-mu-SPE) combined to gas chromatography-mass spectrometry has been applied for the analysis of volatile aromas of liquid essential oils from Bulgarian rose and Provence lavender. The technique uses an adsorbent (Tenax TA) contained in a mulberry paper bag, minimal amount of organic solvent. Linearities for the six-points calibration curves were excellent. LOD values were in the rage from 0.38 ng mL(-1) to 0.77 ng mL(-1). Overall, precision and recovery were generally good. Phenethyl alcohol and citronellol were the main components in the essential oil from Bulgarian rose. Linalyl acetate and linalool were the most abundant components in the essential oils from true lavender or lavandin. Additionally, the relative extraction efficiencies of proposed method have been compared with HS-SPME. The overall extraction efficiency was evaluated by the relative concentration factors (CF) of the several characteristic components. CF values by HS-MPB-mu-SPE were lower than those by headspace solid phase microextraction (HS-SPME). The HS-MPB-mu-SPE method is very simple to use, inexpensive, rapid, requires small sample amounts and solvent consumption. In addition, this method allowed combining of extraction, enrichment, and clean-up in a single step. HS-MPB-mu-SPE and GC/MS is a promising technique for the characterization of volatile aroma compounds from liquid essential oils.

  16. Experimental investigation of bioethanol liquid phase dehydration using natural clinoptilolite

    OpenAIRE

    Karimi, Samira; Ghobadian, Barat; Omidkhah, Mohammad-Reza; Towfighi, Jafar; Tavakkoli Yaraki, Mohammad

    2016-01-01

    An experimental study of bioethanol adsorption on natural Iranian clinoptilolite was carried out. Dynamic breakthrough curves were used to investigate the best adsorption conditions in bioethanol liquid phase. A laboratory setup was designed and fabricated for this purpose. In order to find the best operating conditions, the effect of liquid pressure, temperature and flow rate on breakthrough curves and consequently, maximum ethanol uptake by adsorbent were studied. The effects of different v...

  17. The Molecular Structure of the Liquid Ordered Phase

    Science.gov (United States)

    Lyman, Edward

    2014-03-01

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

  18. Experimental Two-Phase Liquid-Metal Magnetohydrodynamic Generator Program

    Science.gov (United States)

    1979-04-01

    efficiencies in excess of 0.8 are attainable. Initial measurements of local flow parameters in a NaK -nitrogen two-phase liquid - metal MHD generator...hot liquid metals . Thus, the concept of using surface-active aaents in MHD generators can be evaluated more rapidly and inexpensively with NaK , the...describe this aggregation of bchbles as a foam. When the Ba- NaK solution was transferred, helium was blown under the surface of the liquid metal with the

  19. Nematic-like stable glasses without equilibrium liquid crystal phases.

    Science.gov (United States)

    Gómez, Jaritza; Gujral, Ankit; Huang, Chengbin; Bishop, Camille; Yu, Lian; Ediger, M D

    2017-02-07

    We report the thermal and structural properties of glasses of posaconazole, a rod-like molecule, prepared using physical vapor deposition (PVD). PVD glasses of posaconazole can show substantial molecular orientation depending upon the choice of substrate temperature, Tsubstrate, during deposition. Ellipsometry and IR measurements indicate that glasses prepared at Tsubstrate very near the glass transition temperature (Tg) are highly ordered. For these posaconazole glasses, the orientation order parameter is similar to that observed in macroscopically aligned nematic liquid crystals, indicating that the molecules are mostly parallel to one another and perpendicular to the interface. To our knowledge, these are the most anisotropic glasses ever prepared by PVD from a molecule that does not form equilibrium liquid crystal phases. These results are consistent with a previously proposed mechanism in which molecular orientation in PVD glasses is inherited from the orientation present at the free surface of the equilibrium liquid. This mechanism suggests that molecular orientation at the surface of the equilibrium liquid of posaconazole is nematic-like. Posaconazole glasses can show very high kinetic stability; the isothermal transformation of a 400 nm glass into the supercooled liquid occurs via a propagating front that originates at the free surface and requires ∼10(5) times the structural relaxation time of the liquid (τα). We also studied the kinetic stability of PVD glasses of itraconazole, which is a structurally similar molecule with equilibrium liquid crystal phases. While itraconazole glasses can be even more anisotropic than posaconazole glasses, they exhibit lower kinetic stability.

  20. Protein microarrays using liquid phase fractionation of cell lysates.

    Science.gov (United States)

    Yan, Fang; Sreekumar, Arun; Laxman, Bharathi; Chinnaiyan, Arul M; Lubman, David M; Barder, Timothy J

    2003-07-01

    We describe an approach in which protein microarrays are produced using a two-dimensional (2-D) liquid phase fractionation of cell lysates. The method involves a pI-based fractionation using chromatofocusing in the first dimension followed by nonporous reversed-phase high-performance liquid chromatography (HPLC) of each pI fraction in the second dimension. This allows fractionation of cellular proteins in the liquid phase that could then be arrayed on nitrocellulose slides and used to study humoral response in cancer. Protein microarrays have been used to identify potential serum biomarkers for prostate cancer. It is shown that specific fractions are immunoreactive against prostate cancer serum but not against serum from healthy individuals. These proteins could serve as sero-diagnostic markers for prostate cancer. Importantly, this method allows for use of post-translationally modified proteins as baits for detection of humoral response. Proteins eliciting an immune response are identified using the molecular mass and peptide sequence data obtained using mass spectrometric analysis of the liquid fractions. The fractionation of proteins in the liquid phase make this method amenable to automation.

  1. Analysis of Volatile Components of Adenosma indianum (Lour. Merr. by Steam Distillation and Headspace Solid-Phase Microextraction

    Directory of Open Access Journals (Sweden)

    Zhi Zeng

    2013-01-01

    Full Text Available The essential oil of Adenosma indianum (Lour. Merr. plays an important role in its antibacterial and antiphlogistic activities. In this work, the volatile components were extracted by steam distillation (SD and headspace solid-phase microextraction (HS-SPME and analysed by gas chromatography-mass spectrometry (GC-MS. A total of 49 volatile components were identified by GC-MS, and the major volatile components were α-limonene (20.59–35.07%, fenchone (15.79–31.81%, α-caryophyllene (6.98–10.32%, β-caryophyllene (6.98–10.19%, and piperitenone oxide (1.96–11.63%. The comparison of the volatile components from A. indianum (Lour. Merr. grown in two regions of China was reported. Also, the comparison of the volatile components by SD and HS-SPME was discussed. The results showed that the major volatile components of A. indianum (Lour. Merr. from two regions of China were similar but varied with different extraction methods. These results were indicative of the suitability of HS-SPME method for simple, rapid, and solvent-free analysis of the volatile components of the medicinal plants.

  2. Photocatalytic degradation of 2-phenethyl-2-chloroethyl sulfide in liquid and gas phases.

    Science.gov (United States)

    Vorontsov, Alexandre V; Panchenko, Alexander A; Savinov, Evgueni N; Lion, Claude; Smirniotis, Panagiotis G

    2002-12-01

    This work explores the ability of photocatalysis to decontaminate water and air from chemical warfare agent mustard using its simulant 2-phenethyl 2-chloroethyl sulfide (PECES). PECES like mustard slowly dissolves in water with hydrolysis, forming 2-phenethyl 2-hydroxyethyl sulfide (PEHES). Irradiation of TiO2 suspension containing PECES with the unfiltered light of a mercury lamp (lambda > or = 254 nm) decomposed all PECES mostly via photolysis. Reaction under filtered light (lambda > 300 nm) proceeds mainly photocatalytically and requires longer time. Sulfur from starting PECES is completely transformed into sulfuric acid at the end of the reaction. Detected volatile, nonvolatile, surface products, and the suggested scheme of degradation are reported. The main volatile products are styrene and benzaldehyde, nonvolatile--hydroxylated PEHES, surface--2-phenethyl disulfide. Photolysis of PECES produced the same set of volatile products as photocatalysis. Photocatalytic degradation of gaseous PECES in air results in its mineralization but is accompanied by TiO2 deactivation. The highest rate of mineralization with minimum deactivation was observed at about room temperature and a water concentration of 27,500 ppm. No gaseous products except CO2 were detected. The main extracted surface product was styrene. It was concluded that PECES photocatalytic degradation proceeds mainly via C-S bond cleavage and further oxidation of the products. Hydrolysis of the C-S bond was detected only in gas-phase photocatalytic degradation. The quantum efficiency of gas-phase degradation (0.28%) was much higher than that of liquid-phase degradation (0.008%). The results demonstrate the ability of photocatalysis to decontaminate an aqueous and especially an air environment

  3. Bubbles in liquids with phase transition. Part 1. On phase change of a single vapor bubble in liquid water

    Science.gov (United States)

    Dreyer, Wolfgang; Duderstadt, Frank; Hantke, Maren; Warnecke, Gerald

    2012-11-01

    In the forthcoming second part of this paper a system of balance laws for a multi-phase mixture with many dispersed bubbles in liquid is derived where phase transition is taken into account. The exchange terms for mass, momentum and energy explicitly depend on evolution laws for total mass, radius and temperature of single bubbles. Therefore in the current paper we consider a single bubble of vapor and inert gas surrounded by the corresponding liquid phase. The creation of bubbles, e.g. by nucleation is not taken into account. We study the behavior of this bubble due to condensation and evaporation at the interface. The aim is to find evolution laws for total mass, radius and temperature of the bubble, which should be as simple as possible but consider all relevant physical effects. Special attention is given to the effects of surface tension and heat production on the bubble dynamics as well as the propagation of acoustic elastic waves by including slight compressibility of the liquid phase. Separately we study the influence of the three phenomena heat conduction, elastic waves and phase transition on the evolution of the bubble. We find ordinary differential equations that describe the bubble dynamics. It turns out that the elastic waves in the liquid are of greatest importance to the dynamics of the bubble radius. The phase transition has a strong influence on the evolution of the temperature, in particular at the interface. Furthermore the phase transition leads to a drastic change of the water content in the bubble. It is shown that a rebounding bubble is only possible, if it contains in addition an inert gas. In Part 2 of the current paper the equations derived are sought in order to close the system of equations for multi-phase mixture balance laws for dispersed bubbles in liquids involving phase change.

  4. Cluster Monte Carlo and numerical mean field analysis for the water liquid-liquid phase transition

    Science.gov (United States)

    Mazza, Marco G.; Stokely, Kevin; Strekalova, Elena G.; Stanley, H. Eugene; Franzese, Giancarlo

    2009-04-01

    Using Wolff's cluster Monte Carlo simulations and numerical minimization within a mean field approach, we study the low temperature phase diagram of water, adopting a cell model that reproduces the known properties of water in its fluid phases. Both methods allow us to study the thermodynamic behavior of water at temperatures, where other numerical approaches - both Monte Carlo and molecular dynamics - are seriously hampered by the large increase of the correlation times. The cluster algorithm also allows us to emphasize that the liquid-liquid phase transition corresponds to the percolation transition of tetrahedrally ordered water molecules.

  5. Diffractive devices based on blue phase liquid crystals

    Science.gov (United States)

    Li, Yan; Huang, Shuaijia; Su, Yikai

    2016-09-01

    Blue phase liquid crystal (BPLC) has been attractive for display and photonic applications for its sub-millisecond response time, no need for surface alignment, and an optically isotropic dark state. Because of these advantages, diffractive devices based on blue phase liquid crystals have great potential for wide applications. In this work, we present several BPLC diffractive devices. The operation principles, fabrication and experimental measurements will be discussed in details for two BPLC gratings realized by holographic method and a BPLC Fresnel lens using a spatial light modulator projector. All of these devices exhibit several attractive features such as sub-millisecond response, relatively high spatial resolution and polarization-independence.

  6. Determination of sulfonamides in butter samples by ionic liquid magnetic bar liquid-phase microextraction high-performance liquid chromatography.

    Science.gov (United States)

    Wu, Lijie; Song, Ying; Hu, Mingzhu; Xu, Xu; Zhang, Hanqi; Yu, Aimin; Ma, Qiang; Wang, Ziming

    2015-01-01

    A novel, simple, and environmentally friendly pretreatment method, ionic liquid magnetic bar liquid-phase microextraction, was developed for the determination of sulfonamides in butter samples by high-performance liquid chromatography. The ionic liquid magnetic bar was prepared by inserting a stainless steel wire into the hollow of a hollow fiber and immobilizing ionic liquid in the micropores of the hollow fiber. In the extraction process, the ionic liquid magnetic bars were used to stir the mixture of sample and extraction solvent and enrich the sulfonamides in the mixture. After extraction, the analyte-adsorbed ionic liquid magnetic bars were readily isolated with a magnet from the extraction system. It is notable that the present method was environmentally friendly since water and only several microliters of ionic liquid were used in the whole extraction process. Several parameters affecting the extraction efficiency were investigated and optimized, including the type of ionic liquid, sample-to-extraction solvent ratio, the number of ionic liquid magnetic bars, extraction temperature, extraction time, salt concentration, stirring speed, pH of the extraction solvent, and desorption conditions. The recoveries were in the range of 73.25-103.85 % and the relative standard deviations were lower than 6.84 %. The experiment results indicated that the present method was effective for the extraction of sulfonamides in high-fat content samples.

  7. A universal bubble-growth equation for pure liquids and binary solutions with a non-volatile solute

    Energy Technology Data Exchange (ETDEWEB)

    Miyatake, Osamu [Kyushu Univ., Fukuoka (Japan). Dept. of Chemical Engineering; Tanaka, Itsuo [Gifu Univ. (Japan). Dept. of Biological Production System; Lior, N. [Univ. of Pennsylvania, Philadelphia, PA (United States). Dept. of Mechanical Engineering and Applied Mechanics

    1996-12-31

    A simple equation suitable for predicting the growth rate of a vapor bubble in uniformly-superheated pure liquids and in binary solutions with a non-volatile solute was developed. The equation also improves on the popular pure-liquid bubble growth expression of Mikie et al. (1970) in that it is valid throughout the bubble growth history, i.e., in the surface-tension-, inertia-, and heat-transfer-controlled regimes, it accounts for bubble growth acceleration effects, and uses correctly-related and variable fluid properties. It was found to agree very well with experimental data for pure water and for aqueous NaCl solutions. As the bubble growth in superheated solutions with a non-volatile solute was found to be quite insensitive to diffusion and non-equilibrium effects in a broad range of common solution properties, this equation is likely to be universally valid for many liquids and solutions. Bubble growth in superheated fluids is of key interest in boiling phenomena in general and in flash evaporation in particular. Applications include a wide variety of separation processes such as water desalination, and energy conversion processes such as ocean-thermal energy conversion, geothermal power generation, and nuclear reactor safety.

  8. Aqueous-phase oxidation of green leaf volatiles by hydroxyl radical as a source of SOA: Product identification from methyl jasmonate and methyl salicylate oxidation

    Science.gov (United States)

    Hansel, Amie K.; Ehrenhauser, Franz S.; Richards-Henderson, Nicole K.; Anastasio, Cort; Valsaraj, Kalliat T.

    2015-02-01

    Green leaf volatiles (GLVs) are a group of biogenic volatile organic compounds (BVOCs) released into the atmosphere by vegetation. BVOCs produce secondary organic aerosol (SOA) via gas-phase reactions, but little is known of their aqueous-phase oxidation as a source of SOA. GLVs can partition into atmospheric water phases, e.g., fog, mist, dew or rain, and be oxidized by hydroxyl radicals (˙OH). These reactions in the liquid phase also lead to products that have higher molecular weights, increased polarity, and lower vapor pressures, ultimately forming SOA after evaporation of the droplet. To examine this process, we investigated the aqueous, ˙OH-mediated oxidation of methyl jasmonate (MeJa) and methyl salicylate (MeSa), two GLVs that produce aqueous-phase SOA. High performance liquid chromatography/electrospray ionization mass spectrometry (HPLC-ESI-MS) was used to monitor product formation. The oxidation products identified exhibit higher molecular mass than their parent GLV due to either dimerization or the addition of oxygen and hydroxyl functional groups. The proposed structures of potential products are based on mechanistic considerations combined with the HPLC/ESI-MS data. Based on the structures, the vapor pressure and the Henry's law constant were estimated with multiple methods (SPARC, SIMPOL, MPBPVP, Bond and Group Estimations). The estimated vapor pressures of the products identified are significantly (up to 7 orders of magnitude) lower than those of the associated parent compounds, and therefore, the GLV oxidation products may remain as SOA after evaporation of the water droplet. The contribution of the identified oxidation products to SOA formation is estimated based on measured HPLC-ESI/MS responses relative to previous aqueous SOA mass yield measurements.

  9. Volatile constituents of Murraya koenigii fresh leaves using headspace solid phase microextraction--gas chromatography-mass spectrometry.

    Science.gov (United States)

    Sukkaew, Sayamol; Pripdeevech, Patcharee; Thongpoon, Chalermporn; Machan, Theeraphan; Wongchuphan, Rattana

    2014-12-01

    The volatile components of Murraya koenigii fresh leaves, collected from Surat Thani province, Thailand were studied by using headspace (HS) solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS). The four fibers employed to extract the volatiles were polydimethylsiloxane (PDMS), polydimethylsiloxane-divinylbenzene (PDMS-DVB), carboxane-polydimethylsiloxane (CAR-PDMS) and polydimethylsiloxane-divinylbenzene-carboxane (PDMS-DVB-CAR). The volatile constituents of M. koenigii fresh leaves were also extracted by hydrodistillation and analyzed by GC-MS. Fifty-one compounds were identified by these fibers. Five major compounds, γ-terpinene, β-caryophyllene, β-phellandrene, a-selinene and a-pinene, were detected in all fibers. The PDMS-DVB-CAR fiber was considered as the best for trapping key volatiles of M. koenigii fresh leaves.

  10. Non-conventional gas phase remediation of volatile halogenated compounds by dehydrated bacteria.

    Science.gov (United States)

    Erable, Benjamin; Goubet, Isabelle; Seltana, Amira; Maugard, Thierry

    2009-06-01

    Traditional biological removal processes are limited by the low solubility of halogenated compounds in aqueous media. A new technology appears very suitable for the remediation of these volatile organic compounds (VOCs). Solid/gas bio-catalysis applied in VOC remediation can transform halogenated compounds directly in the gas phase using dehydrated cells as a bio-catalyst. The hydrolysis of volatile halogenated substrates into the corresponding alcohol was studied in a solid/gas biofilter where lyophilised bacterial cultures were used as the catalyst. Four strains containing dehalogenase enzymes were tested for the hydrolysis of 1-chlorobutane. The highest removal yield was obtained using the dhaA-containing strains, the maximal reaction rate of 0.8 micromol min(-1)g(-1) being observed with Escherichia coli BL21(DE3)(dhaA). Various treatments such as cell disruption by lysozyme or alkaline gas addition in the bio-filter could stabilise the dehalogenase activity of the bacteria. A pre-treatment of the dehydrated bacterial cells by ammonia vapour improved the stability of the catalyst and a removal activity of 0.9 micromol min(-1)g(-1) was then obtained for 60h. Finally, the process was extended to a range of halogenated substrates including bromo- and chloro-substrates. It was shown that the removal capacity for long halogenated compounds (C(5)-C(6)) was greatly increased relative to traditional biological processes.

  11. Membrane System for Recovery of Volatile Organic Compounds from Remediation Off-Gases.: Phase 1.

    Energy Technology Data Exchange (ETDEWEB)

    Wijmans, J.G.; Goakey, S.; Wang, X.; Baker, R.W.; Kaschemekat, J.H.

    1997-04-01

    In situ vacuum extraction, air or steam sparging, and vitrification are widely used methods of remediating soil contaminated with volatile organic compounds (VOCs). All of these processes produce a VOC-laden air stream from which the VOC must be removed before the air can be discharged or recycled to the generating process. Treatment of these off-gases is often a major portion of the cost of the remediation project. Carbon adsorption and catalytic incineration, the most common methods of treating these gas streams, suffer from significant drawbacks. This report covers the first phase of a two-phase project. The first phase involved the laboratory demonstration of the water separation section of the unit, the production and demonstration of new membrane modules to improve the separation, the design studies required for the demonstration system, and initial contacts with potential field sites. In the second phase, the demonstration system will be built and, after a short laboratory evaluation, will be tested at two field sites.

  12. Phases formed during rapid quenching of liquid carbon

    Science.gov (United States)

    Basharin, A. Yu.; Dozhdikov, V. S.; Dubinchuk, V. T.; Kirillin, A. V.; Lysenko, I. Yu.; Turchaninov, M. A.

    2009-05-01

    Pulsed laser action upon a sample of highly oriented pyrolytic graphite (HOPG) in a gasostat filled with helium at a pressure above that corresponding to the triple point of carbon, followed by rapid quenching of the liquid phase at a rate of about 106 K/s leads to the formation of a crater with a periodic spatial structure at the surface. The composition and structure of nongraphite carbon phases in the near-surface region of the crater have been studied using the Raman scattering spectroscopy, electron microdiffraction, and energy-dispersive X-ray analysis. It is established that rapidly quenched carbon possesses predominantly a hybrid structure of glassy carbon formed as a result of the high-temperature treatment, with inclusions of crystalline carbyne, chaoite, and a hybrid cubic phase of ultradense carbon (C8). The hybrid phases of glassy carbon and C8 had not been reported until now as possible products of solidification of liquid carbon.

  13. Quantitative Analysis of Volatile Impurities in Diallyldimethylammonium Chloride Monomer Solution by Gas Chromatography Coupled with Liquid-Liquid Extraction

    Directory of Open Access Journals (Sweden)

    Cheng Liu

    2017-01-01

    Full Text Available The quantitative analysis method for volatile impurities in diallyldimethylammonium chloride (DADMAC monomer solution was established in this paper. The volatile impurities were quantitatively analyzed with trichloromethane as extraction solvent and n-hexane as internal standard by using gas chromatography (GC coupled with solvent extraction, and the chromatographic conditions, quantitative methods, and extraction conditions were systematically investigated in detail. The results showed that excellent linear relationships of 5 volatile impurities (dimethylamine, allyldimethylamine, allyl chloride, allyl alcohol, and allyl aldehyde were obtained in the range of 1–100 mg·L−1. The method also showed good specificity, recovery (95.0%–107.5%, and relative standard deviation (RSD, 1.40%–7.67%. This method could accurately detect the whole volatile impurities in DADMAC monomer solution quantitatively in one time with a low detection limit. Furthermore, this method is conducive to the preparation of highly pure DADMAC monomer and the development of national and international standards of the DADMAC monomer product quality, and the results could provide a strong foundation for the regulation and mechanism research of impurities on monomer reactivity in polymerization.

  14. Direct monitoring of the liquid and gas phases during a fermentation in a computer-mass-spectrometer-fermentor system

    Energy Technology Data Exchange (ETDEWEB)

    Pungor, E. Jr.; Schaefer, E.J.; Cooney, C.L.; Weaver, J.C.

    1983-01-01

    Measurement of chemical concentrations is a weak link in the monitoring of fermentations. The use of a computer-controlled mass-spectrometer (MS) has made possible the measurement of one or more volatile compounds on an essentially continuous basis, both in the liquid (broth) and the gas (headspace) phases. For our purposes, the MS was used, not as a spectrometer for chemical identification, but as a programmable detector for measuring concentrations of different compounds. Specifically, a computer-controlled MS was employed during the fermentation of Saccharomyces italicus, to monitor N/sub 2/, O/sub 2/, and CO/sub 2/ concentration in the gas phase, and N/sub 2/, O/sub 2/, CO/sub 2/, and ethanol in the liquid phase. The performance of the MS was carefully analyzed.

  15. Analysis of coal tar polycyclic aromatic hydrocarbon LC-fractions by capillary SFC on a liquid crystalline stationary phase

    Energy Technology Data Exchange (ETDEWEB)

    Kithinji, J.P.; Raynor, M.W.; Egia, B.; Davies, I.L.; Bartle, K.D.; Clifford, A.A. (University of Leeds, Leeds (UK). School of Chemistry)

    1990-01-01

    Supercritical fluid chromatography (SFC) on a capillary column coated with a smectic mesomorphic crystalline phase is shown to exhibit a typical turnover effect (retention versus column temperature) for polycyclic aromatic hydrocarbons (PAHs) at lower temperatures than are found on a methylpolysiloxane phase. Liquid chromatography is used to separate various fractions from a coal tar, which are analyzed by high resolution capillary SFC. Different density and temperature programs were investigated to optimize the separations. Simultaneous density and temperature programs gave the best results, and this is thought to be due to increased solute diffusion coefficients which yield highly efficient separations for the high molecular weight polycyclic aromatic hydrocarbons. The separation mechanism is based on the shape of the liquid crystalline phase, solubility, volatility, and molecular geometry of the PAHs.

  16. Recent progress of nuclear liquid gas phase transition

    Institute of Scientific and Technical Information of China (English)

    MA Yu-Gang; SHEN Wen-Qing

    2004-01-01

    Recent progress on nuclear liquid gas phase transition (LGPT) has been reviewed, especially for the signals of LGPT in heavy ion collisions. These signals include the power-law charge distribution, cluster emission rate, nuclear Zipf law, bimodality, the largest fluctuation of the fragments, △ -scaling, caloric curve, phase coexistence diagram, critical temperature, critical exponent analysis, negative specific heat capacity and spinodal instability etc. The systematic works of the authors on experimental and theoretical LGPT are also introduced.

  17. Relaxation of contact-line singularities solely by the Kelvin effect and apparent contact angles for isothermal volatile liquids in contact with air

    Science.gov (United States)

    Rednikov, Alexey; Colinet, Pierre

    2013-11-01

    The contact (triple) line of a volatile liquid on a flat solid is studied theoretically. Like with a pure-vapor atmosphere [Phys. Rev. E 87, 010401, 2013], but here for isothermal diffusion-limited evaporation/condensation in the presence of an inert gas, we rigorously show that the notorious contact-line singularities (related to motion or phase change itself) can be regularized solely on account of the Kelvin effect (curvature dependence of the saturation conditions). No disjoining pressure, precursor films or Navier slip are in fact needed to this purpose, and nor are they taken into consideration here (``minimalist'' approach). The model applies to both perfect (zero Young's angle) and partial wetting, and is in particular used to study the related issue of evaporation-induced contact angles. Their modification by the contact-line motion (either advancing or receding) is assessed. The formulation is posed for a distinguished immediate vicinity of the contact line (the ``microregion''), the corresponding problem decoupling to leading order, here up to one unknown coefficient, from what actually happens at the macroscale. The lubrication approximation (implying sufficiently small contact angles) is used in the liquid, coupled with the diffusion equation in the gaz phase. Supported by ESA and BELSPO PRODEX and F.R.S.-FNRS.

  18. Headspace Solid-Phase Microextraction Analysis of Volatile Components in Phalaenopsis Nobby’s Pacific Sunset

    Directory of Open Access Journals (Sweden)

    Chih-Hsin Yeh

    2014-09-01

    Full Text Available Phalaenopsis is the most important economic crop in the Orchidaceae family. There are currently numerous beautiful and colorful Phalaenopsis flowers, but only a few species of Phalaenopsis have an aroma. This study reports the analysis volatile components present in P. Nobby’s Pacific Sunset by solid-phase microextraction (SPME coupled with gas chromatography (GC and gas chromatography/mass spectrometry (GC-MS. The results show that the optimal extraction conditions were obtained by using a DVB/CAR/PDMS fiber. A total of 31 compounds were identified, with the major compounds being geraniol, linalool and α-farnesene. P. Nobby’s Pacific Sunset had the highest odor concentration from 09:00 to 13:00 on the eighth day of storage. It was also found that in P. Nobby’s Pacific Sunset orchids the dorsal sepals and petals had the highest odor concentrations, whereas the column had the lowest.

  19. Dimensionless ratios: Characteristics of quantum liquids and their phase transitions

    Science.gov (United States)

    Yu, Yi-Cong; Chen, Yang-Yang; Lin, Hai-Qing; Römer, Rudolf A.; Guan, Xi-Wen

    2016-11-01

    Dimensionless ratios of physical properties can characterize low-temperature phases in a wide variety of materials. As such, the Wilson ratio (WR), the Kadowaki-Woods ratio, and the Wiedemann-Franz law capture essential features of Fermi liquids in metals, heavy fermions, etc. Here we prove that the phases of many-body interacting multicomponent quantum liquids in one dimension (1D) can be described by WRs based on the compressibility, susceptibility, and specific heat associated with each component. These WRs arise due to additivity rules within subsystems reminiscent of the rules for multiresistor networks in series and parallel—a novel and useful characteristic of multicomponent Tomonaga-Luttinger liquids (TLL) independent of microscopic details of the systems. Using experimentally realized multispecies cold atomic gases as examples, we prove that the Wilson ratios uniquely identify phases of TLL, while providing universal scaling relations at the boundaries between phases. Their values within a phase are solely determined by the stiffnesses and sound velocities of subsystems and identify the internal degrees of freedom of said phase such as its spin degeneracy. This finding can be directly applied to a wide range of 1D many-body systems and reveals deep physical insights into recent experimental measurements of the universal thermodynamics in ultracold atoms and spins.

  20. Multiple headspace-solid-phase microextraction: An application to quantification of mushroom volatiles

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Rosaria; Tedone, Laura; De Grazia, Selenia [Dipartimento Farmaco-chimico, University of Messina, viale Annunziata, 98168 Messina (Italy); Dugo, Paola [Dipartimento Farmaco-chimico, University of Messina, viale Annunziata, 98168 Messina (Italy); Centro Integrato di Ricerca (C.I.R.), Università Campus-Biomedico, Via Álvaro del Portillo, 21, 00128 Roma (Italy); Mondello, Luigi, E-mail: lmondello@unime.it [Dipartimento Farmaco-chimico, University of Messina, viale Annunziata, 98168 Messina (Italy); Centro Integrato di Ricerca (C.I.R.), Università Campus-Biomedico, Via Álvaro del Portillo, 21, 00128 Roma (Italy)

    2013-04-03

    Highlights: ► Multiple headspace extraction-solid phase microextraction (MHS-SPME) has been applied to the analysis of Agaricus bisporus. ► Mushroom flavor is characterized by the presence of compounds with a 8-carbon atoms skeleton. ► Formation of 8-carbon compounds involves a unique fungal biochemical pathway. ► The MHS-SPME allowed to determine quantitatively 5 target analytes of A. bisporus for the first time. -- Abstract: Multiple headspace-solid phase microextraction (MHS-SPME) followed by gas chromatography/mass spectrometry (GC–MS) and flame ionization detection (GC–FID) was applied to the identification and quantification of volatiles released by the mushroom Agaricus bisporus, also known as champignon. MHS-SPME allows to perform quantitative analysis of volatiles from solid matrices, free of matrix interferences. Samples analyzed were fresh mushrooms (chopped and homogenized) and mushroom-containing food dressings. 1-Octen-3-ol, 3-octanol, 3-octanone, 1-octen-3-one and benzaldehyde were common constituents of the samples analyzed. Method performance has been tested through the evaluation of limit of detection (LoD, range 0.033–0.078 ng), limit of quantification (LoQ, range 0.111–0.259 ng) and analyte recovery (92.3–108.5%). The results obtained showed quantitative differences among the samples, which can be attributed to critical factors, such as the degree of cell damage upon sample preparation, that are here discussed. Considerations on the mushrooms biochemistry and on the basic principles of MHS analysis are also presented.

  1. Characterization and semiquantitative analysis of volatiles in seedless watermelon varieties using solid-phase microextraction.

    Science.gov (United States)

    Beaulieu, John C; Lea, Jeanne M

    2006-10-04

    Seedless triploid watermelons have increased in popularity since the early 1990s, and the demand for seedless fruit is on the rise. Sweetness and sugars are crucial breeding focuses for fruit quality. Volatiles also play an important role; yet, we found no literature for seedless varieties and no reports using solid-phase microextraction (SPME) in watermelon. The objective of this experiment was to identify volatile and semivolatile compounds in five seedless watermelon varieties using carboxen divinylbenzene polydimethylsiloxane solid-phase microextraction (SPME) with gas chromatography-mass spectrometry (GC-MS). Fully ripe watermelon was squeezed through miracloth to produce rapid juice extracts for immediate headspace SPME GC-MS. Aldehydes, alcohols, ketones, and one furan (2-pentyl furan, a lipid oxidation product) were recovered. On the basis of total ion count peak area, the most abundant compounds in five varieties were 3-nonen-1-ol/(E,Z)-2,6-nonadienal (16.5-28.2%), (E)-2-nonenal (10.6-22.5%), and (Z)-6-nonenal (2.0-11.3%). Hexanal was most abundant (37.7%) in one variety (Petite Perfection) [corrected] The most abundant ketone was 6-methyl-5-hepten-2-one (2.7-7.7%). Some sensory attributes reported for these compounds are melon, citrus, cucumber, orange, rose, floral, guava, violet, vegetable, green, grassy, herbaceous, pungent, fatty, sweet, and waxy. Identifying and relating these compounds to sensory attributes will allow for future monitoring of the critical flavor compounds in seedless watermelon after processing and throughout fresh-cut storage.

  2. Effect of Marangoni Convection on Mass Transfer in Liquid Phase

    Institute of Scientific and Technical Information of China (English)

    YU Liming; ZENG Aiwu; YU Kuo Tsung

    2006-01-01

    Marangoni convection and its influence on the mass transfer in the liquid phase were investigated.Marangoni convection was visualized using laser Schlieren technique.Orderly polygonal convection patterns and random interfacial turbulence were observed.The effect of Marangoni convection on the mass transfer rate was studied by desorbing ethanol from aqueous solution in the falling film.The experimental results show that Marangoni convection can speed up the surface renewal and enhance the mass transfer rate in the liquid phase.The liquid mass transfer coefficient can be enhanced by as much as 3 folds.The corresponding empirical correlations are given in terms of the mass transfer enhancement factor.Furthermore,in considering the Marangoni effect,the conventional mass transfer correlation was modified.The differences between the values predicted by the correlation and the experimental data are within ± 8.2% and the average difference is 4.2%.

  3. Kinetics of p-xylene liquid-phase catalytic oxidation

    Energy Technology Data Exchange (ETDEWEB)

    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

    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.

  4. Extraction and Esterification of Low-Titer Short-Chain Volatile Fatty Acids from Anaerobic Fermentation with Ionic Liquids.

    Science.gov (United States)

    Andersen, Stephen J; Berton, Jan K E T; Naert, Pieter; Gildemyn, Sylvia; Rabaey, Korneel; Stevens, Christian V

    2016-08-23

    Ionic liquids can both act as a solvent and mediate esterification to valorize low-titer volatile fatty acids and generate organic solvents from renewable carbon sources including biowaste and CO2 . In this study, four phosphonium ionic liquids were tested for single-stage extraction of acetic acid from a dilute stream and esterification to ethyl acetate with added ethanol and heat. The esterification proceeded with a maximum conversion of 85.9±1.3 % after 30 min at 75 °C at a 1:1 stoichiometric ratio of reactants. Extraction and esterification can be tailored using mixed-anion ionic liquids; this is demonstrated herein using a common trihexyl(tetradecyl)phosphonium cation and a mixed chloride and bis(trifluoromethylsulfonyl)imide anion ionic liquid. As a further proof-of-concept, ethyl acetate was generated from an ionic liquid-driven esterification of an acetic acid extractant generated using CO2 as the only carbon source by microbial electrosynthesis.

  5. Separation of Chlorella vulgaris from liquid phase using bioflocculants

    Directory of Open Access Journals (Sweden)

    Gizem Günay

    2014-12-01

    results showed that C. vulgaris was partially separated from the liquid phase. However, the experiments will continue for the purpose of increasing the flocculating activity. Getting successfully experimental results with kaolin showed that bioflocculant has a potential use in wastewater treatment. For this reason, it also is thought to analyze the effect of bioflocculant on the wastewater treatment with further studies.[¤

  6. Predicting the Liquid Phase Mass Transfer Resistance of Structured Packings

    NARCIS (Netherlands)

    Olujic, Z.; Seibert, A.F.

    2014-01-01

    Published correlations for estimating the liquid phase mass transfer coefficients of structured packings are compared using experimental evidence on the efficiency of Montz-Pak B1–250MN and B1–500MN structured packings as measured in total reflux distillation tests using the chlorobenzene/ethylbenze

  7. Experimental observables on nuclear liquid gas phase transition

    CERN Document Server

    Ma, Y G

    2006-01-01

    Progress on nuclear liquid gas phase transition (LGPT) or critical behavior has been simply reviewed and some signals of LGPT in heavy ion collisions, especially in NIMROD data, are focused. These signals include the power-law charge distribution, the largest fluctuation of the fragment observables, the nuclear Zipf law, caloric curve and critical exponent analysis etc.

  8. Liquid-ordered phases induced by cholesterol: a compendium of binary phase diagrams.

    Science.gov (United States)

    Marsh, Derek

    2010-03-01

    Mixtures of phospholipids with cholesterol are able to form liquid-ordered phases that are characterised by short-range orientational order and long-range translational disorder. These L(o)-phases are distinct from the liquid-disordered, fluid L(alpha)-phases and the solid-ordered, gel L(beta)-phases that are assumed by the phospholipids alone. The liquid-ordered phase can produce spatially separated in-plane fluid domains, which, in the form of lipid rafts, are thought to act as platforms for signalling and membrane sorting in cells. The areas of domain formation are defined by the regions of phase coexistence in the phase diagrams for the binary mixtures of lipid with cholesterol. In this paper, the available binary phase diagrams of lipid-cholesterol mixtures are all collected together. It is found that there is not complete agreement between different determinations of the phase diagrams for the same binary mixture. This can be attributed to the indirect methods largely used to establish the phase boundaries. Intercomparison of the various data sets allows critical assessment of which phase boundaries are rigorously established from direct evidence for phase coexistence.

  9. Liquid-phase reactions induced by atmospheric pressure glow discharge with liquid electrode

    Science.gov (United States)

    Tochikubo, Fumiyoshi; Shirai, Naoki; Uchida, Satoshi

    2014-12-01

    We experimentally investigated some of the initial reactions in a liquid induced by electron or positive-ion irradiation from an atmospheric-pressure dc glow discharge in contact with the liquid. We used an H-shaped glass reactor to observe the effects of electron irradiation and positive-ion irradiation on the liquid-phase reaction separately and simultaneously. Aqueous solutions of NaCl, AgNO3, HAuCl4, and FeCl2 are used as the electrolyte. Solutions of AgNO3 and HAuCl4 are used for the generation of Ag and Au nanoparticles, respectively. Solution of FeCl2 is used for the generation of ferromagnetic particles. Experimental results showed that electron irradiation of the liquid surface generates OH- in water and that positive-ion irradiation of the liquid surface generates H+ in water even without the dissolution of gas-phase nitrogen oxide. A possible reaction process is qualitatively discussed. We also showed that the control of reductive and oxidative environment in the liquid is possible not only by the gas composition for the plasma generation but also by the liquid composition.

  10. Acidic ionic liquids for n-alkane isomerization in a liquid-liquid or slurry-phase reaction mode

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, C.; Hager, V.; Geburtig, D.; Kohr, C.; Wasserscheid, P. [Erlangen-Nuernberg Univ. (Germany). Lehrstuhl fuer Chemische Reaktionstechnik; Haumann, M. [Chemical Reaction Engineering, FAU Busan Campus, Korea (Korea, Republic of)

    2011-07-01

    Highly acidic ionic liquid (IL) catalysts offer the opportunity to convert n-alkanes at very low reaction temperatures. The results of IL catalyzed isomerization and cracking reactions of pure n-octane are presented. Influence of IL composition, [C{sub 4}C{sub 1}Im]Cl / AlCl{sub 3} / H{sub 2}SO{sub 4} and [C{sub 4}C{sub 1}Im]Cl / AlCl{sub 3} / 1-chlorooctane, on catalyst activity and selectivities to branched alkanes was investigated. Acidic chloroaluminate IL catalysts form liquid-liquid biphasic systems with unpolar organic product mixtures. Thus, recycling of the acidic IL is enabled by simple phase separation in the liquid-liquid biphasic reaction mode or the IL can be immobilized on an inorganic support with a large specific surface area. These supported ionic liquid phase (SILP) catalysts offer the advantage to get a macroscopically heterogeneous system while still preserving all benefits of the homogeneous catalyst which can be used for the slurry-phase n-alkane isomerization. The interaction of the solid support and acidic IL influences strongly the catalytic activity. (orig.)

  11. Analysis of black pepper volatiles by solid phase microextraction-gas chromatography: A comparison of terpenes profiles with hydrodistillation.

    Science.gov (United States)

    Jeleń, Henryk H; Gracka, Anna

    2015-10-30

    Solid phase microextraction (SPME) is widely used in food flavor compounds analysis in majority for profiling volatile compounds. Based on such profiles conclusions are often drawn concerning the percentage composition of volatile compounds in particular food, spices or raw materials. This paper focuses on the usefulness of SPME for the profiling of volatile compounds from spices using black pepper as an example. SPME profiles obtained in different analytical conditions were compared to the profile of pepper volatiles obtained using hydrodistillation in Clevenger apparatus. The profiles of both monoterpenes and sesquiterpenes of black pepper were highly dependent on sample weight (0.1 and 1g samples were tested), and extraction time (durations from 2 to 120min were tested), regardless of the SPME fiber used (PDMS and CAR/PDMS coatings were used). The characteristic phenomenon for extraction from dry ground pepper was the decrease of monoterpenes % share in volatiles with increasing extraction times, whereas at the same time the % contents of sesquiterpenes increased. Addition of water to ground pepper substantially changed extraction kinetics and mutual proportions of mono to sesquiterpenes compared to dry samples by minimizing changes in mono- to sesquiterpenes ratio in different extraction times. Obtained results indicate that SPME can be a fast extraction method for volatiles of black pepper. Short extraction times (2-10min) in conjunction with the fast GC analysis (2.1min) proposed here may offer fast alternative to hydrodistillation allowing black pepper terpenes characterization.

  12. Induced smectic phases in phase diagrams of binary nematic liquid crystal mixtures.

    Science.gov (United States)

    Huang, Tsang-Min; McCreary, Kathleen; Garg, Shila; Kyu, Thein

    2011-03-28

    To elucidate induced smectic A and smectic B phases in binary nematic liquid crystal mixtures, a generalized thermodynamic model has been developed in the framework of a combined Flory-Huggins free energy for isotropic mixing, Maier-Saupe free energy for orientational ordering, McMillan free energy for smectic ordering, Chandrasekhar-Clark free energy for hexagonal ordering, and phase field free energy for crystal solidification. Although nematic constituents have no smectic phase, the complexation between these constituent liquid crystal molecules in their mixture resulted in a more stable ordered phase such as smectic A or B phases. Various phase transitions of crystal-smectic, smectic-nematic, and nematic-isotropic phases have been determined by minimizing the above combined free energies with respect to each order parameter of these mesophases. By changing the strengths of anisotropic interaction and hexagonal interaction parameters, the present model captures the induced smectic A or smectic B phases of the binary nematic mixtures. Of particular importance is the fact that the calculated phase diagrams show remarkable agreement with the experimental phase diagrams of binary nematic liquid crystal mixtures involving induced smectic A or induced smectic B phase.

  13. Crystal growth in a three-phase system: diffusion and liquid-liquid phase separation in lysozyme crystal growth.

    Science.gov (United States)

    Heijna, M C R; van Enckevort, W J P; Vlieg, E

    2007-07-01

    In the phase diagram of the protein hen egg-white lysozyme, a region is present in which the lysozyme solution demixes and forms two liquid phases. In situ observations by optical microscopy show that the dense liquid droplets dissolve when crystals grow in this system. During this process the demixed liquid region retracts from the crystal surface. The spatial distribution of the dense phase droplets present special boundary conditions for Fick's second law for diffusion. In combination with the cylindrical symmetry provided by the kinetically roughened crystals, this system allows for a full numerical analysis. Using experimental data for setting the boundary conditions, a quasi-steady-state solution for the time-dependent concentration profile was shown to be valid. Comparison of kinetically rough growth in a phase separated system and in a nonseparated system shows that the growth kinetics for a three-phase system differs from a two-phase system, in that crystals grow more slowly but the duration of growth is prolonged.

  14. Liquid Phase Sintering of Highly Alloyed Stainless Steel

    DEFF Research Database (Denmark)

    Mathiesen, Troels

    1996-01-01

    Liquid phase sintering of stainless steel is usually applied to improve corrosion resistance by obtaining a material without an open pore system. The dense structure normally also give a higher strength when compared to conventional sintered steel. Liquid phase sintrering based on addition...... of boride to AISI 316L type steels have previously been studied, but were found to be sensitive to intergranular corrosion due to formation of intermetallic phases rich in chromium and molybdenum. In order to improve this system further, new investigations have focused on the use of higher alloyed stainless...... steel as base material. The stainless base powders were added different amounts and types of boride and sintered in hydrogen at different temperatures and times in a laboratory furnace. During sintering the outlet gas was analyzed and subsequently related to the obtained microstructure. Thermodynamic...

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

    Science.gov (United States)

    Li, Renzhong; Sun, Gang; Xu, Limei

    2016-08-01

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

  16. Predictions of Phase Distribution in Liquid-Liquid Two-Component Flow

    Science.gov (United States)

    Wang, Xia; Sun, Xiaodong; Duval, Walter M.

    2011-06-01

    Ground-based liquid-liquid two-component flow can be used to study reduced-gravity gas-liquid two-phase flows provided that the two liquids are immiscible with similar densities. In this paper, we present a numerical study of phase distribution in liquid-liquid two-component flows using the Eulerian two-fluid model in FLUENT, together with a one-group interfacial area transport equation (IATE) that takes into account fluid particle interactions, such as coalescence and disintegration. This modeling approach is expected to dynamically capture changes in the interfacial structure. We apply the FLUENT-IATE model to a water-Therminol 59® two-component vertical flow in a 25-mm inner diameter pipe, where the two liquids are immiscible with similar densities (3% difference at 20°C). This study covers bubbly (drop) flow and bubbly-to-slug flow transition regimes with area-averaged void (drop) fractions from 3 to 30%. Comparisons of the numerical results with the experimental data indicate that for bubbly flows, the predictions of the lateral phase distributions using the FLUENT-IATE model are generally more accurate than those using the model without the IATE. In addition, we demonstrate that the coalescence of fluid particles is dominated by wake entrainment and enhanced by increasing either the continuous or dispersed phase velocity. However, the predictions show disagreement with experimental data in some flow conditions for larger void fraction conditions, which fall into the bubbly-to-slug flow transition regime. We conjecture that additional fluid particle interaction mechanisms due to the change of flow regimes are possibly involved.

  17. Studies in Three Phase Gas-Liquid Fluidised Systems

    Science.gov (United States)

    Awofisayo, Joyce Ololade

    1992-01-01

    Available from UMI in association with The British Library. The work is a logical continuation of research started at Aston some years ago when studies were conducted on fermentations in bubble columns. The present work highlights typical design and operating problems that could arise in such systems as waste water, chemical, biochemical and petroleum operations involving three-phase, gas-liquid -solid fluidisation; such systems are in increasing use. It is believed that this is one of few studies concerned with "true" three-phase, gas-liquid-solid fluidised systems, and that this work will contribute significantly to closing some of the gaps in knowledge in this area. The research work was experimentally based and involved studies of the hydrodynamic parameters, phase holdups (gas and solid), particle mixing and segregation, and phase flow dynamics (flow regime and circulation patterns). The studies have focused particularly on the solid behaviour and the influence of properties of solids present on the above parameters in three-phase, gas-liquid-solid fluidised systems containing single particle components and those containing binary and ternary mixtures of particles. All particles were near spherical in shape and two particle sizes and total concentration levels were used. Experiments were carried out in two- and three-dimensional bubble columns. Quantitative results are presented in graphical form and are supported by qualitative results from visual studies which are also shown as schematic diagrams and in photographic form. Gas and solid holdup results are compared for air-water containing single, binary and ternary component particle mixtures. It should be noted that the criteria for selection of the materials used are very important if true three-phase fluidisation is to be achieved: this is very evident when comparing the results with those in the literature. The fluid flow and circulation patterns observed were assessed for validation of the generally

  18. Development and validation of a portable gas phase standard generation and calibration system for volatile organic compounds

    Science.gov (United States)

    P. Veres; J. B. Gilman; J. M. Roberts; W. C. Kuster; C. Warneke; I. R. Burling; J. de Gouw

    2010-01-01

    We report on the development of an accurate, portable, dynamic calibration system for volatile organic compounds (VOCs). The Mobile Organic Carbon Calibration System (MOCCS) combines the production of gas-phase VOC standards using permeation or diffusion sources with quantitative total organic carbon (TOC) conversion on a palladium surface to CO2 in the presence of...

  19. Highly Selective Continuous Gas-Phase Methoxycarbonylation of Ethylene with Supported Ionic Liquid Phase (SILP) Catalysts

    DEFF Research Database (Denmark)

    Khokarale, Santosh Govind; Garcia Suárez, Eduardo José; Fehrmann, Rasmus

    2017-01-01

    Supported ionic liquid phase (SILP) technology was applied for the first time to the Pd-catalyzed continuous, gas-phase methoxycarbonylation of ethylene to selectively produce methyl propanoate (MP) in high yields. The influence of catalyst and reaction parameters such as, for example, ionic liqu...

  20. Vapor phase versus liquid phase grafting of meso-porous alumina

    NARCIS (Netherlands)

    Sripathi, V.G.P.; Mojet, B.L.; Nijmeijer, A.; Benes, N.E.

    2013-01-01

    Functionalization of meso-porous c-alumina has been performed by grafting of 3-Aminopropyltrimethoxysilane (3APTMS) simultaneously from either the liquid phase or from the vapor phase. In both cases, after grafting nitrogen physisorption indicates that the materials remain meso-porous with significa

  1. Continuous gas-phase hydroformylation of 1-butene using supported ionic liquid phase (SILP) catalysts

    DEFF Research Database (Denmark)

    Haumann, Marco; Dentler, Katharina; Joni, Joni;

    2007-01-01

    The concept of supported ionic liquid phase (SILP) catalysis has been extended to 1-butene hydroformylation. A rhodium-sulfoxantphos complex was dissolved in [BMIM][n-C8H17OSO3] and this solution was highly dispersed on silica. Continuous gas-phase experiments in a fixed-bed reactor revealed...

  2. Vapor phase versus liquid phase grafting of meso-porous alumina

    NARCIS (Netherlands)

    Sripathi, V.G.P.; Mojet, Barbara; Nijmeijer, Arian; Benes, Nieck Edwin

    2013-01-01

    Functionalization of meso-porous c-alumina has been performed by grafting of 3-Aminopropyltrimethoxysilane (3APTMS) simultaneously from either the liquid phase or from the vapor phase. In both cases, after grafting nitrogen physisorption indicates that the materials remain meso-porous with

  3. Phase distribution in horizontal gas-liquid two-phase bubbly flow

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    An investigation on phase distribution in air-water two-phaseflow in horizontal circular channel was conducted by using the double-sensor resistivity probe. The variations of phase distribution with variations ofgas and liquid volumetric fluxes were analyzed and the present data werecompared with some of other researcher's data and existing models. It wasfound there exists more complicated phase distribution pattern in horizontalflow system than in vertical flow. The radial local void fraction profilesare similar at the same measurement angle with various gas and liquid flowrates. However, an asymmetric profile can be observed at a given slice ofthe pipe cross-section.

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

    Science.gov (United States)

    Cubrović, Mihailo; Zaanen, Jan; Schalm, Koenraad

    2009-07-24

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

  5. CELLULOSE EXTRACTION FROM PALM KERNEL CAKE USING LIQUID PHASE OXIDATION

    OpenAIRE

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

    2009-01-01

    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 is basically a two-step process. Palm kernel cake was pretreated in hot water at 180°C and followed by liquid ...

  6. Water Phase Diagram Is Significantly Altered by Imidazolium Ionic Liquid

    DEFF Research Database (Denmark)

    Chaban, V. V.; Prezhdo, O. V.

    2014-01-01

    We report unusually large changes in the boiling temperature, saturated vapor pressure, and structure of the liquid-vapor interface for a range of 1-butyl-3-methyl tetrafluoroborate, [C4C1IM][BF4]-water mixtures. Even modest molar fractions of [C4C1IM][BF4] significantly affect the phase behavior...... of water, as represented, for instance, by strong negative deviations from Raoult's law, extending far beyond the standard descriptions. The investigation was carried out using classical molecular dynamics employing a specifically refined force field. The changes in the liquid-vapor interface and saturated...

  7. Position for determining gas-phase volatile organic compound concentrations in transuranic waste containers. Revision 2

    Energy Technology Data Exchange (ETDEWEB)

    Connolly, M.J.; Liekhus, K.J. [Lockheed Martin Idaho Technologies Co., Idaho Falls, ID (United States). Idaho National Engineering and Environmental Lab.; Djordjevic, S.M.; Loehr, C.A.; Spangler, L.R. [Benchmark Environmental Corp. (United States)

    1998-06-01

    In the conditional no-migration determination (NMD) for the test phase of the Waste Isolation Pilot Plant (WIPP), the US Environmental Protection Agency (EPA) imposed certain conditions on the US Department of Energy (DOE) regarding gas phase volatile organic compound (VOC) concentrations in the void space of transuranic (TRU) waste containers. Specifically, the EPA required the DOE to ensure that each waste container has no layer of confinement that contains flammable mixtures of gases or mixtures of gases that could become flammable when mixed with air. The EPA also required that sampling of the headspace of waste containers outside inner layers of confinement be representative of the entire void space of the container. The EPA stated that all layers of confinement in a container would have to be sampled until DOE can demonstrate to the EPA that sampling of all layers is either unnecessary or can be safely reduced. A test program was conducted at the Idaho National Engineering and Environmental Laboratory (INEEL) to demonstrate that the gas phase VOC concentration in the void space of each layer of confinement in vented drums can be estimated from measured drum headspace using a theoretical transport model and that sampling of each layer of confinement is unnecessary. This report summarizes the studies performed in the INEEL test program and extends them for the purpose of developing a methodology for determining gas phase VOC concentrations in both vented and unvented TRU waste containers. The methodology specifies conditions under which waste drum headspace gases can be said to be representative of drum gases as a whole and describes a method for predicting drum concentrations in situations where the headspace concentration is not representative. The methodology addresses the approach for determining the drum VOC gas content for two purposes: operational period drum handling and operational period no-migration calculations.

  8. Plasmas in Multiphase Media: Bubble Enhanced Discharges in Liquids and Plasma/Liquid Phase Boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Kushner, Mark Jay [University of Michigan

    2014-07-10

    In this research project, the interaction of atmospheric pressure plasmas with multi-phase media was computationally investigated. Multi-phase media includes liquids, particles, complex materials and porous surfaces. Although this investigation addressed fundamental plasma transport and chemical processes, the outcomes directly and beneficially affected applications including biotechnology, medicine and environmental remediation (e.g., water purification). During this project, we made advances in our understanding of the interaction of atmospheric pressure plasmas in the form of dielectric barrier discharges and plasma jets with organic materials and liquids. We also made advances in our ability to use computer modeling to represent these complex processes. We determined the method that atmospheric pressure plasmas flow along solid and liquid surfaces, and through endoscopic like tubes, deliver optical and high energy ion activation energy to organic and liquid surfaces, and produce reactivity in thin liquid layers, as might cover a wound. We determined the mechanisms whereby plasmas can deliver activation energy to the inside of liquids by sustaining plasmas in bubbles. These findings are important to the advancement of new technology areas such as plasma medicine

  9. Reduction of water consumption in bioethanol production from triticale by recycling the stillage liquid phase

    Directory of Open Access Journals (Sweden)

    Małgorzata Gumienna

    2011-12-01

    Full Text Available   Background. The distillery stillage is a major and arduous byproduct generated during ethanol production in distilleries. The aim of this study was to evaluate the possibility of the stillage recirculation in the mashing process of triticale for non-byproducts production and reducing the fresh water consumption. The number of recirculation cycles which can be applied without disturbances in the ethanol fermentation process was investigated. Material and methods. Winter triticale BOGO and “Ethanol Red” Saccharomyces cerevisiae yeast were used in the experiments. The method of non-pressure cooking was used for gelatinizingthe triticale, commercial α-amylase SPEZYME ETHYL and glucoamylase FERMENZYME L-400 were applied for starch liquefaction and saccharification. The process was conducted at 30°C for 72 h, next after distillation the stillage was centrifuged and the liquid fraction was used instead of 75% of process water. Results. Ethanol yield from triticale fermentations during 40 cycles ranged between 82% and 95% of theoretical yield preserving yeast vitality and quantity on the same level. The obtained distillates were characterized with enhanced volatile compounds (fusel oil, esters, aldehydes, methanol as well as protein and potassium concentrations. Conclusions. The liquid part of stillage was proved that can be reused instead of water in bioethanol production from triticale, without disturbing the fermentation process. This investigated solution of distillery byproducts utilization (liquid phase of stillage constitutes the way which could significantly decrease the bioethanol production costs by reducing the water consumption, as well as wastewater production.  

  10. LIQUID PHASE FLOW ESTIMATION IN GAS-LIQUID TWO-PHASE FLOW USING INVERSE ANALYSIS AND PARTICLE TRACKING VELOCIMETRY

    Institute of Scientific and Technical Information of China (English)

    CHENG Wen; MURAI Yuichi; SASAKI Toshio; YAMAMOTO Fujio

    2004-01-01

    An inverse analysis algorithm is proposed for estimating liquid phase flow field from measurement data of bubble motion. This kind of technology will be applied in future for various estimation of fluid flow in rivers, lakes, sea surface flow, and also microscopic channel flow as the problem-handling in civil, mechanical, electronic, and chemical engineering. The relationship between the dispersion motion and the carrier phase flow is governed and expressed by the translational motion equation of spherical dispersion. The equation consists of all the force components including inertia, added inertia, drag, lift, pressure gradient force and gravity force. Using this equation enables us to estimate the carrier phase flow structure using only the data of the dispersion motion. Whole field liquid flow structure is also estimated using spatial or temporal interpolation method. In order to verify this principle, the Taylor-Green vortex flow, and the Karman vortex shedding from a square cylinder have been chosen. The results show that the combination of the inverse analysis and Particle Tracking Velocimetry (PTV) with the spatio-temporal post-processing algorithm could reconstruct well the carrier phase flow of the gas-liquid two-phase flow.

  11. Conformation of alkanes in the gas phase and pure liquids.

    Science.gov (United States)

    Thomas, Laura L; Christakis, Theodore J; Jorgensen, William L

    2006-10-26

    Monte Carlo (MC) statistical mechanics simulations have been carried out for the homologous alkane series of n-butane through n-dodecane in the gas phase and for the pure liquids at 298 K and 1 atm using the OPLS-AA force field. The study addresses potential cumulative deviations of computed properties and potential conformational differences between the gas phase and pure liquids, for example, from self-solvation in the gas phase. The average errors in comparison with experimental data for the computed densities and heats of vaporization are modest at 0.7% and 6.9%, respectively. Also, the invariant gas and liquid-phase results for average end-to-end distances and percentages of trans conformations for each nonterminal C-C bond assert that the conformer populations are not altered upon transfer from the gas phase to the pure liquid for the n-alkanes in this size range. Average end-to-end distances were also computed from the results of conformational searches and corroborated the MC findings. Quantitatively, the OPLS-AA result for the trans population of the C3-C4 bond in n-undecane is in close agreement with the findings from (13)C NMR experiments. Finally, previous work on determining the shortest n-alkane that does not have an all-trans global energy minimum has been extended. The smallest n-alkane with a hairpin geometry that is lower in energy than the all-trans conformer occurs for C(22)H(46) with OPLS-AA, though with a correction for GG sequences, the true turning point is likely in the C(16)-C(18) range.

  12. Phase transformation and liquid density redistribution during solidification of Ni-based superalloy Inconel 718

    National Research Council Canada - National Science Library

    Wang Ling Gong He Zhao Haofeng Dong Jianxin Zhang Maicang

    2012-01-01

    .... It was found that significant segregation in liquid prompts high Nb phase to precipitate directly from liquid, which results in the redistribution of alloy elements and liquid density in their vicinity. The term...

  13. Structure, Hydrodynamics, and Phase Transition of Freely Suspended Liquid Crystals

    Science.gov (United States)

    Clark, Noel A.

    2000-01-01

    Smectic liquid crystals are phases of rod shaped molecules organized into one dimensionally (1D) periodic arrays of layers, each layer being between one and two molecular lengths thick. In the least ordered smectic phases, the smectics A and C, each layer is a two dimensional (2D) liquid. Additionally there are a variety of more ordered smectic phases having hexatic short range translational order or 2D crystalline quasi long range translational order within the layers. The inherent fluid-layer structure and low vapor pressure of smectic liquid crystals enable the long term stabilization of freely suspended, single component, layered fluid films as thin as 30A, a single molecular layer. The layering forces the films to be an integral number of smectic layers thick, quantizing their thickness in layer units and forcing a film of a particular number of layers to be physically homogeneous with respect to its layer structure over its entire area. Optical reflectivity enables the precise determination of the number of layers. These ultrathin freely suspended liquid crystal films are structures of fundamental interest in condensed matter and fluid physics. They are the thinnest known stable condensed phase fluid structures and have the largest surface-to-volume ratio of any stable fluid preparation, making them ideal for the study of the effects of reduced dimensionality on phase behavior and on fluctuation and interface phenomena. Their low vapor pressure and quantized thickness enable the effective use of microgravity to extend the study of basic capillary phenomena to ultrathin fluid films. Freely suspended films have been a wellspring of new liquid crystal physics. They have been used to provide unique experimental conditions for the study of condensed phase transitions in two dimensions. They are the only system in which the hexatic has been unambiguously identified as a phase of matter, and the only physical system in which fluctuations of a 2D XY system and

  14. Gas-Liquid Two-Phase Flows Through Packed Bed Reactors in Microgravity

    Science.gov (United States)

    Motil, Brian J.; Balakotaiah, Vemuri

    2001-01-01

    The simultaneous flow of gas and liquid through a fixed bed of particles occurs in many unit operations of interest to the designers of space-based as well as terrestrial equipment. Examples include separation columns, gas-liquid reactors, humidification, drying, extraction, and leaching. These operations are critical to a wide variety of industries such as petroleum, pharmaceutical, mining, biological, and chemical. NASA recognizes that similar operations will need to be performed in space and on planetary bodies such as Mars if we are to achieve our goals of human exploration and the development of space. The goal of this research is to understand how to apply our current understanding of two-phase fluid flow through fixed-bed reactors to zero- or partial-gravity environments. Previous experiments by NASA have shown that reactors designed to work on Earth do not necessarily function in a similar manner in space. Two experiments, the Water Processor Assembly and the Volatile Removal Assembly have encountered difficulties in predicting and controlling the distribution of the phases (a crucial element in the operation of this type of reactor) as well as the overall pressure drop.

  15. Molecular ions of ionic liquids in the gas phase.

    Science.gov (United States)

    Gross, Jürgen H

    2008-09-01

    Ionic liquids form neutral ion pairs (CA) upon evaporation. The softness of the gas-phase ionization of field ionization has been used to generate "molecular ions," CA(+*), of ionic liquids, most probably by neutralization of the anion. In detail, 1-ethyl-3-methylimidazolium-thiocyanate, [C(6)H(11)N(2)](+) [SCN](-), 1-butyl-3-methylimidazolium-tricyanomethide, [C(8)H(15)N(2)](+) [C(4)N(3)](-), N-butyl-3-methylpyridinium-dicyanamide, [C(10)H(16)N](+) [C(2)N(3)](-), and 1-butyl-1-methylpyrrolidinium-bis[(trifluormethyl)sulfonyl]amide, [C(9)H(20)N](+) [C(2)F(6)NO(4)S(2)](-) were used. The assignment as CA(+*) ions, which has been confirmed by accurate mass measurements and misassignments due to thermal decomposition of the ionic liquids, has been ruled out by field desorption and electrospray ionization mass spectrometry of the residues.

  16. Study on seafood volatile profile characteristics during storage and its potential use for freshness evaluation by headspace solid phase microextraction coupled with gas chromatography-mass spectrometry.

    Science.gov (United States)

    Zhang, Zhuomin; Li, Gongke; Luo, Lin; Chen, Guonan

    2010-02-05

    Seafood volatile profile characteristics at different storage phases are various and can be used for freshness evaluation during storage. It is imperative to obtain the full volatile information prior to the further study of seafood volatile profile characteristics during storage. Also, the efficient data-processing method is another important factor for the interpretation of seafood volatile profile characteristics during storage and related potential volatile markers. In this work, a new analytical strategy, including the efficient sampling technique, sensitive detection and suitable data-processing method, for seafood freshness evaluation was developed based on the volatile profile characteristics during storage. First, the study of volatiles of seafood samples including razor clam, redspot swimming crab and prawn at different storage phases were conducted by headspace solid phase microextraction (HSSPME) followed by gas chromatography-mass spectrometry (GC-MS) detection. Then, seafood volatile profile characteristics at different storage phases were statistically interpreted by a combination data-processing method including normalization, principle component analysis (PCA) and common model strategy. The different seafood volatile profile characteristics and potential volatile markers were attempted to be distilled. The results tentatively suggested that the different seafood volatile profile characteristics during storage could reflect the transitional changing seafood freshness and provide more precise warning information for seafood spoilage during storage than any single chemical markers. This work developed an analytical method for study of seafood volatile profile characteristics and tentatively proposed a new idea of using seafood volatile profile characteristics during storage for the freshness evaluation from the point of view of analytical chemistry.

  17. Development and validation of a reversed phase liquid chromatographic method for analysis of griseofulvin and impurities.

    Science.gov (United States)

    Kahsay, Getu; Adegoke, Aremu Olajire; Van Schepdael, Ann; Adams, Erwin

    2013-06-01

    A simple and robust reversed phase liquid chromatographic method was developed and validated for the quantitative determination of griseofulvin (GF) and its impurities in drug substances and drug products (tablets). Chromatographic separation was achieved on a Discovery C18 (250mm×4.6mm, 5μm) column kept at 30°C. The mobile phase consisted of a gradient mixture of mobile phase A (water-0.1% formic acid pH 4.5, 80:20, v/v) and B (ACN-water-0.1% formic acid pH 4.5, 65:15:20, v/v/v) pumped at a flow rate of 1.0mL/min. UV detection was performed at 290nm. The method was validated for its robustness, sensitivity, precision, accuracy and linearity based on ICH guidelines. The robustness study was performed by means of an experimental design and multivariate analysis. Satisfactory results were obtained from the validation studies. The use of volatile mobile phases allowed for the identification of three main impurities present above the identification threshold using mass spectrometry (MS). The developed LC method has been applied for the assay and impurity determination of GF drug substances and tablets. The method could be very useful for the quality control of GF and its impurities in bulk and formulated dosage forms.

  18. Preconcentration in gas or liquid phases using adsorbent thin films

    Directory of Open Access Journals (Sweden)

    Antonio Pereira Nascimento Filho

    2006-03-01

    Full Text Available The possibility of preconcentration on microchannels for organic compounds in gas or liquid phases was evaluated. Microstructures with different geometries were mechanically machined using poly(methyl methacrylate - PMMA as substrates and some cavities were covered with cellulose. The surfaces of the microchannels were modified by plasma deposition of hydrophilic or hydrophobic films using 2-propanol and hexamethyldisilazane (HMDS, respectively. Double layers of HMDS + 2-propanol were also used. Adsorption characterization was made by Quartz Crystal Measurements (QCM technique using reactants in a large polarity range that showed the adsorption ability of the structures depends more on the films used than on the capillary phenomena. Cellulose modified by double layer film showed a high retention capacity for all gaseous compounds tested. However, structures without plasma deposition showed low retention capacity. Microchannels modified with double layers or 2-propanol plasma films showed higher retention than non-modified ones on gas or liquid phase.

  19. Liquid-Phase Back mixing in Bubble Columns

    Directory of Open Access Journals (Sweden)

    Burhan S. Abdulrazak

    2013-05-01

    Full Text Available Liquid-phase axial dispersion coefficients have been measured for air-water system in bubble columns of 10, 15 and 30 cm diameter. The experiments are carried out using a transient method (the tracer response method.  Dispersion coefficient is obtained by adjusting the experimental profiles of tracer concentration with the predictions of the model. The experimental results show that one-dimensional axial dispersion coefficient, Dax,L, reveal strong scale dependence. Backmixing of liquid phase increases with the increase of reactor diameter and superficial gas velocity.  Axial dispersion coefficient for large column reactors can be easily predicted from the developed relation . Comparison of calculated with the experimental data and with the published data of other authors shows good agreement which ensure the reliability and confusability of the adopted correlations to be used in further design and scale-up purposes. 

  20. Powder metallurgy: Solid and liquid phase sintering of copper

    Science.gov (United States)

    Sheldon, Rex; Weiser, Martin W.

    1993-01-01

    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.

  1. Vitrification and Crystallization of Phase-Separated Metallic Liquid

    Directory of Open Access Journals (Sweden)

    Yun Cheng

    2017-02-01

    Full Text Available The liquid–liquid phase separation (LLPS behavior of Fe50Cu50 melt from 3500 K to 300 K with different rapid quenching is investigated by molecular dynamics (MD simulation based on the embedded atom method (EAM. The liquid undergoes metastable phase separation by spinodal decomposition in the undercooled regime and subsequently solidifies into three different Fe-rich microstructures: the interconnected-type structure is kept in the glass and crystal at a higher cooling rate, while the Fe-rich droplets are found to crystalize at a lower cooling rate. During the crystallization process, only Fe-rich clusters can act as the solid nuclei. The twinning planes can be observed in the crystal and only the homogeneous atomic stacking shows mirror symmetry along the twinning boundary. Our present work provides atomic-scale understanding of LLPS melt during the cooling process.

  2. Entransy dissipation minimization for liquid-solid phase change processes

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The liquid-solid phase change process of a simple one-dimensional slab is studied in this paper.By taking entransy dissipation minimization as optimization objective,the optimal external reservoir temperature profiles are derived by using optimal control theory under the condition of a fixed freezing or melting time.The entransy dissipation corresponding to the optimal heat exchange strategies of minimum entransy dissipation is 8/9 of that corresponding to constant reservoir temperature operations,which is independent of all system parameters.The obtained results for entransy dissipation minimization are also compared with those obtained for the optimal heat exchange strategies of minimum entropy generation and constant reservoir temperature operations by numerical examples.The obtained results can provide some theoretical guidelines for the choice of optimal cooling or heating strategy in practical liquid-solid phase change processes.

  3. Processes of microstructure coarsening at liquid phase sintering.

    Science.gov (United States)

    Anestiev, L; Froyen, L

    2000-06-01

    A different approach to the theoretical description of the classical theory of Ostwald ripening at liquid phase sintering has been proposed. The model developed in the present approach is based on an equation describing the growth kinetics of the particles, which is different from those used until now. The model developed here accounts automatically for the influence of the initial volume fraction and predicts correctly: the time dependence of rho; at t-->infinity-rho;(3)(t)-rho;(3)(0)=Kt; the form of the distribution function after considerable coarsening time; the experimentally observed values for the relation rho(max)/rho;; and the phenomena of "abnormal growth" at liquid phase sintering.

  4. Modeling Non-aqueous Phase Liquid Displacement Process

    Institute of Scientific and Technical Information of China (English)

    Yang Zhenqing; Shao Changjin; Zhou Guanggang; Qiu Chao

    2007-01-01

    A pore-network model physically based on pore level multiphase flow was used to study the water-non-aqueous phase liquid (NAPL) displacement process, especially the effects of wettability, water-NAPL interfacial tension, the fraction of NAPL-wet pores, and initial water saturation on the displacement. The computed data show that with the wettability of the mineral surfaces changing from strongly water-wet to NAPL-wet, capillary pressure and the NAPL relative permeability gradually decrease, while water-NAPL interfacial tension has little effect on water relative permeability, but initial water saturation has a strong effect on water and NAPL relative permeabilities. The analytical results may help to understand the micro-structure displacement process of non-aqueous phase liquid and to provide the theoretical basis for controlling NAPL migration.

  5. Solid phase microextraction of volatile emissions of Ceratitis capitata (Wiedemann) (Diptera: Tephritidae): influence of fly sex, age, and mating status.

    Science.gov (United States)

    Alfaro, Cristina; Vacas, Sandra; Zarzo, Manuel; Navarro-Llopis, Vicente; Primo, Jaime

    2011-01-12

    Considerable efforts have been devoted to understanding the courtship behavior and pheromone communication of medflies; however, the sex pheromone composition is still a controversial subject. The discovery of new components affecting medfly behavior would be of interest for medfly control methods based on semiochemicals. This work describes volatile compounds emitted by Ceratitis capitata collected using solid phase microextraction. The volatile study was conducted according to an experimental design with three factors (sex, age, and mating status) assumed to be relevant for better understanding the chemical communication. Emission data were treated by means of principal component analysis, a statistical methodology not previously applied to the study of volatiles emitted by fruit flies. The characterization of emission patterns could be useful for the selection of compounds to be further investigated in biological assays to improve knowledge of the key semiochemicals involved in medfly behavior.

  6. Headspace solid phase microextraction (HSSPME) for the determination of volatile and semivolatile pollutants in soils

    Energy Technology Data Exchange (ETDEWEB)

    Llompart, Maria [Departamento de Quimica Analitica Nutricion y Bromatologia, Facultad de Quimica, Universidad de Santiago de Compostela, E-15706 Santiago de Compostela (Spain); Li, Ken; Fingas, Merv [Emergencies Science Division, Environment Canada, Environmental Technology Centre, 3439 River Road, Ottawa, ON (Canada)

    1999-02-08

    We have investigated the use of headspace solid phase microextraction (HSSPME) as a sample concentration and preparation technique for the analysis of volatile and semivolatile pollutants in soil samples. Soil samples were suspended in solvent and the SPME fibre suspended in the headspace above the slurry. Finally, the fibre was desorbed in the Gas Chromatograph (GC) injection port and the analysis of the samples was carried out. Since the transfer of contaminants from the soil to the SPME fibre involves four separate phases (soil-solvent-headspace and fibre coating), parameters affecting the distribution of the analytes were investigated. Using a well-aged artificially spiked garden soil, different solvents (both organic and aqueous) were used to enhance the release of the contaminants from the solid matrix to the headspace. It was found that simple addition of water is adequate for the purpose of analysing the target volatile organic chemicals (VOCs) in soil. The addition of 1 ml of water to 1 g of soil yielded maximum response. Without water addition, the target VOCs were almost not released from the matrix and a poor response was observed. The effect of headspace volume on response as well as the addition of salt were also investigated. Comparison studies between conventional static headspace (HS) at high temperature (95C) and the new technology HSSPME at room temperature (=20C) were performed. The results obtained with both techniques were in good agreement. HSSPME precision and linearity were found to be better than automated headspace method and HSSPME also produced a significant enhancement in response. The detection and quantification limits for the target VOCs in soils were in the sub-ng g{sup -1} level. Finally, we tried to extend the applicability of the method to the analysis of semivolatiles. For these studies, two natural soils contaminated with diesel fuel and wood preservative, as well as a standard urban dust contaminated with polyaromatic

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

    Science.gov (United States)

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

    2012-03-02

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

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

    OpenAIRE

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

    2015-01-01

    Chalcogen-hyperdoped silicon shows potential applications in silicon-based infrared photodetectors and intermediate band solar cells. Due to the low solid solubility limits of chalcogen elements in silicon, these materials were previously realized by femtosecond or nanosecond laser annealing of implanted silicon or bare silicon in certain background gases. The high energy density deposited on the silicon surface leads to a liquid phase and the fast recrystallization velocity allows trapping o...

  9. A Review of Liquid Phase Epitaxial Grown Gallium Arsenide

    OpenAIRE

    Alexiev, D.; Prokopovich, D. A.; Thomson, S.; Mo, L.; Rosenfeld, A B; Reinhard, M

    2004-01-01

    Liquid phase epitaxy of gallium arsenide (LPE GaAs) has been investigated intensively from the late 1960's to the present and has now a special place in the manufacture of wide band, compound semiconductor radiation detectors. Although this particular process appears to have gained prominence in the last three decades, it is interesting to note that its origins reach back to 1836 when Frankenheim made his first observations. A brief review is presented from a semiconductor applications point ...

  10. Confinement-Driven Phase Separation of Quantum Liquid Mixtures

    Science.gov (United States)

    Prisk, T. R.; Pantalei, C.; Kaiser, H.; Sokol, P. E.

    2012-08-01

    We report small-angle neutron scattering studies of liquid helium mixtures confined in Mobil Crystalline Material-41 (MCM-41), a porous silica glass with narrow cylindrical nanopores (d=3.4nm). MCM-41 is an ideal model adsorbent for fundamental studies of gas sorption in porous media because its monodisperse pores are arranged in a 2D triangular lattice. The small-angle scattering consists of a series of diffraction peaks whose intensities are determined by how the imbibed liquid fills the pores. Pure He4 adsorbed in the pores show classic, layer-by-layer film growth as a function of pore filling, leaving the long range symmetry of the system intact. In contrast, the adsorption of He3-He4 mixtures produces a structure incommensurate with the pore lattice. Neither capillary condensation nor preferential adsorption of one helium isotope to the pore walls can provide the symmetry-breaking mechanism. The scattering is consistent with the formation of randomly distributed liquid-liquid microdomains ˜2.3nm in size, providing evidence that confinement in a nanometer scale capillary can drive local phase separation in quantum liquid mixtures.

  11. Shock wave of vapor-liquid two-phase flow

    Institute of Scientific and Technical Information of China (English)

    Liangju ZHAO; Fei WANG; Hong GAO; Jingwen TANG; Yuexiang YUAN

    2008-01-01

    The shock wave of vapor-liquid two-phase flow in a pressure-gain steam injector is studied by build-ing a mathematic model and making calculations. The results show that after the shock, the vapor is nearly com-pletely condensed. The upstream Mach number and the volume ratio of vapor have a great effect on the shock. The pressure and Mach number of two-phase shock con-form to the shock of ideal gas. The analysis of available energy shows that the shock is an irreversible process with entropy increase.

  12. Self-polarizing terahertz liquid crystal phase shifter

    Directory of Open Access Journals (Sweden)

    Xiao-wen Lin

    2011-09-01

    Full Text Available Using sub-wavelength metallic gratings as both transparent electrodes and broadband high-efficiency polarizers, a highly-compact self-polarizing phase shifter is demonstrated by electrically tuning the effective birefringence of a nematic liquid crystal cell. The metal grating polarizers ensure a good polarizing efficiency in the range of 0.2 to 2 THz. Phase shift of more than π/3 is achieved in a 256 μm-thick cell with a saturation root mean square voltage of around 130 V in this integrated device.

  13. Perhydroazulene-based liquid-crystalline materials with smectic phases.

    Science.gov (United States)

    Hussain, Zakir; Hopf, Henning; Eichhorn, S Holger

    2012-01-01

    New liquid-crystalline materials with a perhydroazulene core were synthesized and the stereochemistry of these compounds was investigated. The mesomorphic properties of the new LC compounds were investigated by differential scanning colorimetry, polarizing optical microscopy and X-ray diffraction. We report here on the LC properties of nonchiral materials, which predominantly exhibit smectic phases and display nematic phases only within narrow temperature ranges. The dependence of the mesogenic behavior of the new materials on the stereochemistry of the core system was also investigated. All newly synthesized compounds were fully characterized by the usual spectroscopic and analytical methods.

  14. Perhydroazulene-based liquid-crystalline materials with smectic phases

    Directory of Open Access Journals (Sweden)

    Zakir Hussain

    2012-03-01

    Full Text Available New liquid-crystalline materials with a perhydroazulene core were synthesized and the stereochemistry of these compounds was investigated. The mesomorphic properties of the new LC compounds were investigated by differential scanning colorimetry, polarizing optical microscopy and X-ray diffraction. We report here on the LC properties of nonchiral materials, which predominantly exhibit smectic phases and display nematic phases only within narrow temperature ranges. The dependence of the mesogenic behavior of the new materials on the stereochemistry of the core system was also investigated. All newly synthesized compounds were fully characterized by the usual spectroscopic and analytical methods.

  15. Determination of volatile compounds in four commercial samples of Japanese green algae using solid phase microextraction gas chromatography mass spectrometry.

    Science.gov (United States)

    Yamamoto, Masayoshi; Baldermann, Susanne; Yoshikawa, Keisuke; Fujita, Akira; Mase, Nobuyuki; Watanabe, Naoharu

    2014-01-01

    Green algae are of great economic importance. Seaweed is consumed fresh or as seasoning in Japan. The commercial value is determined by quality, color, and flavor and is also strongly influenced by the production area. Our research, based on solid phase microextraction gas chromatography mass spectrometry (SPME-GC-MS), has revealed that volatile compounds differ intensely in the four varieties of commercial green algae. Accordingly, 41 major volatile compounds were identified. Heptadecene was the most abundant compound from Okayama (Ulva prolifera), Tokushima (Ulva prolifera), and Ehime prefecture (Ulva linza). Apocarotenoids, such as ionones, and their derivatives were prominent volatiles in algae from Okayama (Ulva prolifera) and Tokushima prefecture (Ulva prolifera). Volatile, short chained apocarotenoids are among the most potent flavor components and contribute to the flavor of fresh, processed algae, and algae-based products. Benzaldehyde was predominant in seaweed from Shizuoka prefecture (Monostroma nitidum). Multivariant statistical analysis (PCA) enabled simple discrimination of the samples based on their volatile profiles. This work shows the potential of SPME-GC-MS coupled with multivariant analysis to discriminate between samples of different geographical and botanical origins and form the basis for development of authentication methods of green algae products, including seasonings.

  16. Transparent nematic phase in a liquid-crystal-based microemulsion.

    Science.gov (United States)

    Yamamoto, J; Tanaka, H

    2001-01-18

    Complex fluids are usually produced by mixing together several distinct components, the interactions between which can give rise to unusual optical and rheological properties of the system as a whole. For example, the properties of microemulsions (composed of water, oil and surfactants) are determined by the microscopic structural organization of the fluid that occurs owing to phase separation of the component elements. Here we investigate the effect of introducing an additional organizing factor into such a fluid system, by replacing the oil component of a conventional water-in-oil microemulsion with an intrinsically anisotropic fluid--a nematic liquid crystal. As with the conventional case, the fluid phase-separates into an emulsion of water microdroplets (stabilized by the surfactant as inverse micelles) dispersed in the 'oil' phase. But the properties are further influenced by a significant directional coupling between the liquid-crystal molecules and the surfactant tails that emerge (essentially radially) from the micelles. The result is a modified bulk-liquid crystal that is an ordered nematic at the mesoscopic level, but which does not exhibit the strong light scattering generally associated with bulk nematic order: the bulk material here is essentially isotropic and thus transparent.

  17. Extraction of proteins with ionic liquid aqueous two-phase system based on guanidine ionic liquid.

    Science.gov (United States)

    Zeng, Qun; Wang, Yuzhi; Li, Na; Huang, Xiu; Ding, Xueqin; Lin, Xiao; Huang, Songyun; Liu, Xiaojie

    2013-11-15

    Eight kinds of green ionic liquids were synthesized, and an ionic liquid aqueous two-phase system (ILATPS) based on 1,1,3,3-tetramethylguandine acrylate (TMGA) guanidine ionic liquid was first time studied for the extraction of proteins. Single factor experiments proved that the extraction efficiency of bovine serum albumin (BSA) was influenced by the mass of IL, K2HPO4 and BSA, also related to the separation time and temperature. The optimum conditions were determined through orthogonal experiment by the five factors described above. The results showed that under the optimum conditions, the extraction efficiency could reach up to 99.6243%. The relative standard deviations (RSD) of extraction efficiencies in precision experiment, repeatability experiment and stability experiment were 0.8156% (n=5), 1.6173% (n=5) and 1.6292% (n=5), respectively. UV-vis and FT-IR spectra confirmed that there were no chemical interactions between BSA and ionic liquid in the extraction process, and the conformation of the protein was not changed after extraction. The conductivity, DLS and TEM were combined to investigate the microstructure of the top phase and the possible mechanism for the extraction. The results showed that hydrophobic interaction, hydrogen bonding interaction and the salt out effect played important roles in the transferring process, and the aggregation and embrace phenomenon was the main driving force for the separation. All these results proved that guanidine ionic liquid-based ATPSs have the potential to offer new possibility in the extraction of proteins.

  18. Influence of microwave heating on liquid-liquid phase inversion and temperature rates for immiscible mixtures.

    Science.gov (United States)

    Kennedy, Alvin; Tadesse, Solomon; Nunes, Janine; Reznik, Aron

    2011-01-01

    Time dependencies of component temperatures for mixtures of immiscible liquids during microwave heating were studied for acetonitrile-cyclohexane and water-toluene. For the first time, we report microwave induced liquid-liquid phase inversion for acetonitrile-cyclohexane mixture: acetonitrile layer was initially at the bottom of the mixture, after 10 sec of microwave heating its density decreased and it inverted to the top of the mixture for the remainder of the microwave heating. This phase inversion could not be achieved by conventional radiant heating. The maximum rate of temperature growth for the polar component of the mixtures was 2 - 5 times larger than for the non-polar component. This suggests that microwave energy is absorbed by polar liquids (water or acetonitrile) and heat is transferred into the non-polar liquid (toluene or cyclohexane) in the mixture by conduction (in case of cyclohexane) or conduction and convection (in case of toluene). Comparison between experimental data and semi-empirical mathematical models, proposed in [Kennedy et at., 2009] showed good correlation. Average relative error between theoretical and experimental results did not exceed 7%. These results can be used to model the temperature kinetics of components for other multiphase mixtures.

  19. Modeling the solid-liquid phase transition in saturated triglycerides

    Science.gov (United States)

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

    2010-02-01

    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 ΔH. 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 ΔH 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 ΔH 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

  20. Liquid-liquid phase separation in aerosol particles: imaging at the nanometer scale.

    Science.gov (United States)

    O'Brien, Rachel E; Wang, Bingbing; Kelly, Stephen T; Lundt, Nils; You, Yuan; Bertram, Allan K; Leone, Stephen R; Laskin, Alexander; Gilles, Mary K

    2015-04-21

    Atmospheric aerosols can undergo phase transitions including liquid-liquid phase separation (LLPS) while responding to changes in the ambient relative humidity (RH). Here, we report results of chemical imaging experiments using environmental scanning electron microscopy (ESEM) and scanning transmission X-ray microscopy (STXM) to investigate the LLPS of micrometer-sized particles undergoing a full hydration-dehydration cycle. Internally mixed particles composed of ammonium sulfate (AS) and either: limonene secondary organic carbon (LSOC), α, 4-dihydroxy-3-methoxybenzeneaceticacid (HMMA), or polyethylene glycol (PEG-400) were studied. Events of LLPS were observed for all samples with both techniques. Chemical imaging with STXM showed that both LSOC/AS and HMMA/AS particles were never homogeneously mixed for all measured RH's above the deliquescence point and that the majority of the organic component was located in the outer phase. The outer phase composition was estimated as 65:35 organic: inorganic in LSOC/AS and as 50:50 organic: inorganic for HMMA/AS. PEG-400/AS particles showed fully homogeneous mixtures at high RH and phase separated below 89-92% RH with an estimated 70:30% organic to inorganic mix in the outer phase. These two chemical imaging techniques are well suited for in situ analysis of the hygroscopic behavior, phase separation, and surface composition of collected ambient aerosol particles.

  1. Boson peak, Ioffe-Regel Crossover, and Liquid-Liquid phase transition in Supercooled Water

    Science.gov (United States)

    Kumar, Pradeep

    We have investigated the onset of Boson peak in a model of liquid water which exhibits a clear first-order phase transition between a low-density liquid phase and a high-density liquid phase of water at low temperature and high pressure. We find that the at low pressures, the onset of Boson peak coincides with the Widom-line of the system. At high pressures, the onset occurs at the transition temperature between the two liquids. Furthermore, we show that at both low and high pressure, the frequency of the Boson peak coincides with the Ioffe-Regel crossover of the transverse phonons, suggesting that the breakdown of Debye behavior is a general feature of Ioffe-Regel limit crossover in supercooled water. The frequency of the Boson peak is weakly pressure dependent and decreases with increasing pressure. Our work bridges gap between the experimental results on the Boson peak nanoconfined water and the behavior that one would expect from a bulk system.

  2. Comparison of two extraction techniques, solid-phase microextraction versus continuous liquid-liquid extraction/solvent-assisted flavor evaporation, for the analysis of flavor compounds in gueuze lambic beer.

    Science.gov (United States)

    Thompson-Witrick, Katherine A; Rouseff, Russell L; Cadawallader, Keith R; Duncan, Susan E; Eigel, William N; Tanko, James M; O'Keefe, Sean F

    2015-03-01

    Lambic is a beer style that undergoes spontaneous fermentation and is traditionally produced in the Payottenland region of Belgium, a valley on the Senne River west of Brussels. This region appears to have the perfect combination of airborne microorganisms required for lambic's spontaneous fermentation. Gueuze lambic is a substyle of lambic that is made by mixing young (approximately 1 year) and old (approximately 2 to 3 years) lambics with subsequent bottle conditioning. We compared 2 extraction techniques, solid-phase microextraction (SPME) and continuous liquid-liquid extraction/solvent-assisted flavor evaporation (CCLE/SAFE), for the isolation of volatile compounds in commercially produced gueuze lambic beer. Fifty-four volatile compounds were identified and could be divided into acids (14), alcohols (12), aldehydes (3), esters (20), phenols (3), and miscellaneous (2). SPME extracted a total of 40 volatile compounds, whereas CLLE/SAFE extracted 36 volatile compounds. CLLE/SAFE extracted a greater number of acids than SPME, whereas SPME was able to isolate a greater number of esters. Neither extraction technique proved to be clearly superior and both extraction methods can be utilized for the isolation of volatile compounds found in gueuze lambic beer.

  3. Measurement of vapor-liquid-liquid phase equilibrium-Equipment and results

    DEFF Research Database (Denmark)

    Frost, Michael Grynnerup; von Solms, Nicolas; Richon, Dominique;

    2015-01-01

    -water-gas hydrate inhibitor systems, at temperatures ranging from 283 to 353 K and at pressures up to 40 MPa. The core of the equipment is an equilibrium cell, equipped with sapphire windows and connected to an analytical system by capillary samplers.New vapor-liquid-liquid equilibrium data are reported for methane......+ n-hexane + methanol + water at 296.2 K and pressures of 6 to 10 MPa. The Cubic-Plus-Association (CPA) equation of state is used to model the phase equilibria data measured. A good agreement between predictions and experimental data is observed, supporting the reliability of the new data. (C) 2015...

  4. Substitution effect in reversible gel-liquid phase transformation polyoxometalate ionic liquid compounds.

    Science.gov (United States)

    Wu, Xuefei; Cai, Huaxue; Wu, Qingyin; Yan, Wenfu

    2016-07-28

    The substitution effect in a series of POM-type reversible gel-liquid phase transformation ionic liquid compounds, [MIMPS]8P2W16V2O62, [MIMPS]6H2P2W16V2O62 and [MIMPS]4H4P2W16V2O62, has been investigated. Interestingly, there is an obvious substitution effect on the physicochemical properties of these compounds. When protons are substituted in place of ammonium, both the conductivity and the thermo-stability of the compounds can be increased a lot, and more protons can enhance this tendency.

  5. Communication: Protein dynamical transition vs. liquid-liquid phase transition in protein hydration water

    Science.gov (United States)

    Schirò, Giorgio; Fomina, Margarita; Cupane, Antonio

    2013-09-01

    In this work, we compare experimental data on myoglobin hydrated powders from elastic neutron scattering, broadband dielectric spectroscopy, and differential scanning calorimetry. Our aim is to obtain new insights on the connection between the protein dynamical transition, a fundamental phenomenon observed in proteins whose physical origin is highly debated, and the liquid-liquid phase transition (LLPT) possibly occurring in protein hydration water and related to the existence of a low temperature critical point in supercooled water. Our results provide a consistent thermodynamic/dynamic description which gives experimental support to the LLPT hypothesis and further reveals how fundamental properties of water and proteins are tightly related.

  6. CO2 Capture with Liquid-Liquid Phase Change Solvents: A Thermodynamic Study

    DEFF Research Database (Denmark)

    Waseem Arshad, Muhammad; Fosbøl, Philip Loldrup; von Solms, Nicolas

    2017-01-01

    Extended UNIQUAC thermodynamic framework was implemented in this work to model the aqueous blend of N, N-Diethylethanolamine (DEEA) and N-Methyl-1,3-diaminopropane (MAPA) for CO2 capture. The model parameters were estimated first for the two ternary systems, H2O-DEEA-CO2 and H2O-MAPA-CO2, followed...... by the quaternary H2O-DEEAMAPA-CO2 system which gives liquid-liquid phase split when reacted with carbon dioxide. A total of 94 model parameters and 6 thermodynamic properties were fitted to approximately 1500 equilibrium and thermal experimental data consisting of pureamine vapor pressure (Pvap), vapor...

  7. Variational studies of exotic bose liquid, spin liquid, and magnetic phases

    Science.gov (United States)

    Tay, Tiamhock

    The strong interest in strongly correlated systems in condensed matter physics has continued unabated for the past few decades. In recent years, the number of novel, exotic quantum phases found in theoretical studies has seen a phenomenal rise. Among those interesting quantum states are bose liquids and spin liquids, where strong quantum fluctuations have prevented the systems from developing a long range order. Our work in this thesis seeks to further the understanding of frustrated systems. In the study of a hard-core boson model with ring-only exchange interactions on a square lattice, we obtain concrete numerical realization of the unconventional Exciton Bose Liquid (EBL) phase, which possesses interesting properties such as a "Bose surface'' which resembles the Fermi surface in a metal, as well as unusual thermodynamic properties such as a T log T dependence for specific heat. An equally important result from this work is the demonstration that the widely used Gutzwiller projection on slave-particle wave functions may generally fail to capture the correct long wavelength physics in the respective systems. For the Heisenberg antiferromagnet on the kagome lattice, which is a promising candidate for realizing a spin-disordered ground state, our variational study shows that the projected Schwinger boson wave function is energetically better than the Dirac spin liquid wave function when a small antiferromagnetic second-neighbor spin coupling is added to the nearest-neighbor model. We also study the anisotropic triangular Heisenberg antiferromagnetic in magnetic field, and find simple, yet accurate wave functions for various regions of the surprisingly rich phase diagram, thus providing insights into the energetics of the competing phases in this interesting model. Finally, our work also highlights permanent-type wave functions as potentially useful constructions in variational studies of systems with short-ranged correlations, e.g., a Mott insulator and a gapped

  8. Determination of volatile organic compounds in river water by solid phase extraction and gas chromatography

    Institute of Scientific and Technical Information of China (English)

    M. A. Mottaleb; M. Z. Abedin; M. S. Islam

    2004-01-01

    A simple, rapid, and reproducible method is described employing solid-phase extraction(SPE) using dichloromethane followed by gas chromatography(GC) with flame ionization detection(FID) for determination of volatile organic compound(VOC) from the Buriganga River water of Bangladesh. The method was applied to detect the benzene, toluene, ethylbenzene, xylene and cumene(BTEXC) in the sample collected from the surface or 15 cm depth of water. Two-hundred ml of n-hexane-pretreated and filtered water samples were applied directly to a C18 SPE column. BTEXC were extracted with dichloromethane and average concentrations were obtained as 0.104 to 0.372 (g/ml. The highest concentration of benzene was found as 0.372 (g/ml with a relative standard deviation(RSD) of 6.2%, and cumene was not detected. Factors influencing SPE e.g., adsorbent types, sample load volume, eluting solvent, headspace and temperatures, were investigated. A cartridge containing a C18 adsorbent and using dichloromethane gave better performance for extraction of BTEXC from water.Average recoveries exceeding 90% could be achieved for cumene at 4℃with a 2.7%RSD

  9. Phase-Change Nanoparticles Using Highly Volatile Perfluorocarbons: Toward a Platform for Extravascular Ultrasound Imaging

    Directory of Open Access Journals (Sweden)

    Terry O. Matsunaga, Paul S. Sheeran, Samantha Luois, Jason E. Streeter, Lee B. Mullin, Bhaskar Banerjee, Paul A. Dayton

    2012-01-01

    Full Text Available Recent efforts using perfluorocarbon (PFC nanoparticles in conjunction with acoustic droplet vaporization has introduced the possibility of expanding the diagnostic and therapeutic capability of ultrasound contrast agents to beyond the vascular space. Our laboratories have developed phase-change nanoparticles (PCNs from the highly volatile PFCs decafluorobutane (DFB, bp =-2 °C and octafluoropropane (OFP, bp =-37 °C for acoustic droplet vaporization. Studies with commonly used clinical ultrasound scanners have demonstrated the ability to vaporize PCN emulsions with frequencies and mechanical indices that may significantly decrease tissue bioeffects. In addition, these contrast agents can be formulated to be stable at physiological temperatures and the perfluorocarbons can be mixed to modulate the balance between sensitivity to ultrasound and general stability. We herein discuss our recent efforts to develop finely-tuned diagnostic/molecular imaging agents for tissue interrogation. We discuss studies currently under investigation as well as potential diagnostic and therapeutic paradigms that may emerge as a result of formulating PCNs with low boiling point PFCs.

  10. Simultaneous determination of volatile and non-volatile nitrosamines in processed meat products by liquid chromatography tandem mass spectrometry using atmospheric pressure chemical ionisation and electrospray ionisation

    DEFF Research Database (Denmark)

    Herrmann, Susan Strange; Duedahl-Olesen, Lene; Granby, Kit

    2014-01-01

    A sensitive, selective and generic method has been developed for the simultaneous determination of the contents (μgkg−1 range) of both volatile nitrosamines (VNA) and non-volatile nitrosamines (NVNA) in processed meat products. The extraction procedure only requires basic laboratory equipment and...

  11. Electrostatic levitation studies of supercooled liquids and metastable solid phases

    Science.gov (United States)

    Rustan, Gustav Errol

    been carried out to study the metastable phase formation in an Fe83B17 near eutectic alloy. Initial supercooling measurements using the ISU-ESL identified the formation of three metastable phases: a precipitate phase that shows stable coexistence with the deeply supercooled liquid, and two distinct bulk solidification phases. To identify the structure of the metastable phases, the Washington University Beamline ESL (WU-BESL) has been used to perform in-situ high energy x-ray diffraction measurements of the metastable phases. Based on the x-ray results, the precipitate phase has been identified as bcc-Fe, and the more commonly occurring bulk solidification product has been found to be a two-phase mixture of Fe23B6 plus fcc-Fe, which appears, upon cooling, to transform into a three phase mixture of Fe23B6, bcc-Fe, and an as-yet unidentified phase, with the transformation occurring at approximately the expected fcc-to-bcc transformation temperature of pure Fe. To further characterize the multi-phase metastable alloy, the ISU-ESL has been used to perform measurements of volume thermal expansion via the videographic technique, as well as RF susceptibility via the TDO technique. The results of the thermal expansion and susceptibility data have been found to be sensitive indicators of additional structural changes that may be occurring in the metastable solid at temperatures below 1000 K, and the susceptibility data has revealed that three distinct ferromagnetic phase transitions take place within the multi-phase mixture. Based on these results, it has been hypothesized that there may be an additional transformation taking place that leads to the formation of either bct- or o-Fe3B in addition to the Fe23B6 phase, although further work is required to test this hypothesis.

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

    Science.gov (United States)

    Pawar, Nisha; Bohidar, H. B.

    2010-09-01

    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) (σ23)3r/Φ23c≥((64)/(9α2))(χ23Φ3)2 , (ii) r≥[(64(χ23Φ3)2)/(9α2σ233)]1/2 , (iii) χ23≥((2χ231-1))/(Φ23cΦ3) , and (iv) (σ23)2/I≥(8)/(3α)(2χ231-1) (where σ23 is the surface charge on the complex formed due to binding of the polyelectrolyte and macroion, Φ23c is the critical volume fraction of the complex, χ23 is the Flory interaction parameter between polyelectrolyte and macroion, χ231 is the same between solvent and the complex, Φ3 is the volume fraction of the macroions, I is the ionic strength of the solution, α 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, δΦ23˜χ2312 (where δΦ23 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.

  13. Asymmetric dynamic phase holographic grating in nematic liquid crystal

    Science.gov (United States)

    Ren, Chang-Yu; Shi, Hong-Xin; Ai, Yan-Bao; Yin, Xiang-Bao; Wang, Feng; Ding, Hong-Wei

    2016-09-01

    A new scheme for recording a dynamic phase grating with an asymmetric profile in C60-doped homeotropically aligned nematic liquid crystal (NLC) was presented. An oblique incidence beam was used to record the thin asymmetric dynamic phase holographic grating. The diffraction efficiency we achieved is more than 40%, exceeding the theoretical limit for symmetric profile gratings. Both facts can be explained by assuming that a grating with an asymmetric saw-tooth profile is formed in the NLC. Finally, physical mechanism and mathematical model for characterizing the asymmetric phase holographic grating were presented, based on the photo-refractive-like (PR-like) effect. Project supported by the Science and Technology Programs of the Educational Committee of Heilongjiang Province, China (Grant No. 12541730) and the National Natural Science Foundation of China (Grant No. 61405057).

  14. CELLULOSE EXTRACTION FROM PALM KERNEL CAKE USING LIQUID PHASE OXIDATION

    Directory of Open Access Journals (Sweden)

    FARM YAN YAN

    2009-03-01

    Full Text Available 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 is basically a two-step process. Palm kernel cake was pretreated in hot water at 180°C and followed by liquid oxidation process with 30% H2O2 at 60°C at atmospheric pressure. The process parameters are hot water treatment time, ratio of palm kernel cake to H2O2, liquid oxidation reaction temperature and time. Analysis of the process parameters on production cellulose from palm kernel cake was performed by using Response Surface Methodology. The recovered cellulose was further characterized by Fourier Transform Infrared (FTIR. Through the hot water treatment, hemicellulose in the palm kernel cake was successfully recovered as saccharides and thus leaving lignin and cellulose. Lignin was converted to water soluble compounds in liquid oxidation step which contains small molecular weight fatty acid as HCOOH and CH3COOH and almost pure cellulose was recovered.

  15. Liquid phase epitaxial growth of bismuth based superconductors

    Science.gov (United States)

    Takemoto, J.; Miyashita, S.; Inoue, T.; Komatsu, H.

    1996-05-01

    The liquid phase epitaxial growth of superconducting films of Bi 2Sr 2CaCu 2O y (2212 phase) and Bi 2Sr 2CuO z (2201 phase) were carried out on three types of substrates; SrTiO 3, LaAlO 3 and NdGaO 3. Twinning structures of the 2212 phase were observed in the films grown on the SrTiO 3 (100) and LaAlO 3 (100) substrates which belong to the cubic crystal system, while nearly twin-free structures were obtained when the film was grown on the NdGaO 3 (001) substrate (orthorhombic system). Atomic force microscopy revealed a 2201 phase film with a reasonably flat area (several μm 2) grown on the LaAlO 3 (100) substrate. It was observed that the 2212 phase nucleated on the substrate following the Volmer-Weber type mechanism (three-dimensional island growth mode). The enlarging processes of the island layers were discussed.

  16. Liquid Crystal Phase Behaviour of Attractive Disc-Like Particles

    Directory of Open Access Journals (Sweden)

    George Jackson

    2013-08-01

    Full Text Available We employ a generalized van der Waals-Onsager perturbation theory to construct a free energy functional capable of describing the thermodynamic properties and orientational order of the isotropic and nematic phases of attractive disc particles. The model mesogen is a hard (purely repulsive cylindrical disc particle decorated with an anisotropic square-well attractive potential placed at the centre of mass. Even for isotropic attractive interactions, the resulting overall inter-particle potential is anisotropic, due to the orientation-dependent excluded volume of the underlying hard core. An algebraic equation of state for attractive disc particles is developed by adopting the Onsager trial function to characterize the orientational order in the nematic phase. The theory is then used to represent the fluid-phase behaviour (vapour-liquid, isotropic-nematic, and nematic-nematic of the oblate attractive particles for varying values of the molecular aspect ratio and parameters of the attractive potential. When compared to the phase diagram of their athermal analogues, it is seen that the addition of an attractive interaction facilitates the formation of orientationally-ordered phases. Most interestingly, for certain aspect ratios, a coexistence between two anisotropic nematic phases is exhibited by the attractive disc-like fluids.

  17. Partitioning and phase equilibria of PEGylated excipients in fluorinated liquids.

    Science.gov (United States)

    Paul, Alison; Talbot, Gemma L; Bowles, James W; James, Jennifer; Griffiths, Peter C; Rogueda, Philippe G

    2010-03-15

    Mixtures of common polymeric excipients and hydrofluoroalkane (HFA) liquids show rich and complex phase behaviour. Phase diagrams and phase compositions are reported for poly(ethylene glycol)s with varying levels of end-group methylation in mixed solvent systems consisting of the model propellant 2H,3H-perfluoropentane (HPFP) and the fully fluorinated analogue perfluoropentane (PFP). Studies have been performed as a function of molecular weight as well as end group chemistry (monomethyl, MM; dimethyl, DM; and dihydroxyl, DH), and for binary polymer mixtures in HPFP/PFP solvent systems. The solvent composition required to induce phase separation by addition of the non-hydrogen bonding PFP is strongly dependent on end-group concentrations. It shows a linear increase with increasing methylation, whilst remaining insensitive to OH group concentration in dihydroxylated PEG systems. For single polymer systems it is observed that strong partitioning of the polymer is observed, and changes in polymer concentration occurring across the phase diagram are a result of changing solvent partitioning between upper and lower phases. These solvent effects are dependent on the composition (wt% PFP) in the solvent mixture. The linear dependence of solvent composition required to induce phase separation at fixed polymer concentration on end group concentrations can be used to predict the phase behaviour for mixtures of monomethylated PEG with either dimethyl or dihydroxyl PEGs, whereas mixtures of dihydroxyl with dimethyl end-capped PEGs show a deviation from linear behaviour with dominance of the dihydroxyl end groups, which is reflected in the obtained phase diagrams. This study hence progresses understanding of factors that influence solubility of PEG-type polymers in HFAs and will facilitate the identification of predictive methodologies for formulation.

  18. Solution processing of polymer semiconductor: Insulator blends-Tailored optical properties through liquid-liquid phase separation control

    KAUST Repository

    Hellmann, Christoph

    2014-12-17

    © 2014 Wiley Periodicals, Inc. It has been demonstrated that the 0-0 absorption transition of poly(3-hexylthiophene) (P3HT) in blends with poly(ethylene oxide) (PEO) could be rationally tuned through the control of the liquid-liquid phase separation process during solution deposition. Pronounced J-like aggregation behavior, characteristic for systems of a low exciton band width, was found for blends where the most pronounced liquid-liquid phase separation occurred in solution, leading to domains of P3HT and PEO of high phase purity. Since liquid-liquid phase separation could be readily manipulated either by the solution temperature, solute concentration, or deposition temperature, to name a few parameters, our findings promise the design from the out-set of semiconductor:insulator architectures of pre-defined properties by manipulation of the interaction parameter between the solutes as well as the respective solute:solvent system using classical polymer science principles.

  19. Supersolidus Liquid Phase Sintering Modeling of Inconel 718 Superalloy

    Science.gov (United States)

    Levasseur, David; Brochu, Mathieu

    2016-02-01

    Powder metallurgy of Inconel 718 superalloy is advantageous as a near-net shape process for complex parts to reduce the buy-to-fly ratio and machining cost. However, sintering Inconel 718 requires the assistance of supersolidus liquid formation to achieve near full density and involves the risk of distortion at high temperatures. The present work is focused on modeling the onset of sintering and distortion as a function of temperature, grain size, and part geometry for Inconel 718. Using experimental sintering results and data available in the literature, the supersolidus liquid phase sintering of Inconel 718 was modeled. The model was used to define a processing window where part distortion would be avoided.

  20. Theoretical and experimental investigation into the explosive boiling potential of thermally stratified liquid-liquid systems

    NARCIS (Netherlands)

    Fabiano, B.; Kersten, R.J.A.; Opschoor, G.; Pastorino, R.

    2002-01-01

    The occurrence of a rapid phase transition, or so-called explosive boiling, when a cold volatile liquid comes into contact with a hot liquid or hot surface is a potential hazard in industry. This study was focused on the explosive boiling potential of thermally stratified liquid-liquid systems that

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

    Energy Technology Data Exchange (ETDEWEB)

    He Yi [Department of Sciences, John Jay College of Criminal Justice, City University of New York, 445 W 59th Street, New York, NY 10019 (United States)]. E-mail: yhe@jjay.cuny.edu; Vargas, Angelica [Department of Sciences, John Jay College of Criminal Justice, City University of New York, 445 W 59th Street, New York, NY 10019 (United States); Kang, Youn-Jung [Department of Sciences, John Jay College of Criminal Justice, City University of New York, 445 W 59th Street, New York, NY 10019 (United States)

    2007-04-25

    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{sub 3}PO{sub 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 {mu}g L{sup -1}, repeatability of the extraction (R.S.D. < 5%, n = 6), and low detection limits (0.3 {mu}g L{sup -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.

  2. Phase relations and volatiles content of the Minopoli2 Campi Flegrei caldera shoshonitic magma

    Science.gov (United States)

    Mangiacapra, A.; Rutherford, M.; Civetta, L.

    2009-04-01

    New constraints on pre-eruption conditions of the Minopoli2 shoshonitic magma are provided by experimental studies. The products of this eruption represent the least evolved magma composition erupted in the first epoch of Campi Flegrei caldera activity (10.3-9.5 ka). Recent geochemical investigations (Mangiacapra et al.,2008)* on dissolved volatiles in the Minopoli2 phenocryst-hosted melt inclusions (MIs), revealed a H2O- and CO2-rich shoshonitic magma, stored at two depths (8-9 and 2-3 km) where it experienced both open-system degassing, driven by crystallization, and flushing with a CO2-rich gas phase coming from deeper levels. Phase equilibrium experiments dry and with 3.5wt% H2O have been guided by the dissolved H2O and CO2 in MIs. The phase equilibria of the shoshonite with 3.5 wt% H2O shows that the observed phenocryst assemblage (olivine, Ca-pyroxene, plagioclase and biotite) becomes stable at 1020±15 °C over the pressure range of 40 to 150 MPa and to higher pressures. The experimental data indicate that the shoshonite crystallised the phenocryst assemblage (15 vol%) at a depth of circa 9 Km and 1025 °C; only small degrees of additional crystallization occurred as the magma ascended to a depth of circa 3 km with degassing of some MIs. Sulphur speciation in glassy MIs was determined as ≥ 79% sulphate which is equivalent to a log fO2≥ NNO + 1.5. The low end of the fO2 range is interpreted to represent the pre-eruption magma at depth. The solubility of CO2 and H2O as a function of pressure in the Minopoli2 shoshonite have been experimentally calibrated. These results contribute to the understanding of magma chamber processes and conduit dynamics, relevant parameters for hazard assessment. * Mangiacapra A., R. Moretti, M. Rutherford, L. Civetta, G. Orsi and P. Papale (2008) The deep magmatic system of the Camp Flegrei caldera (Italy). Geophys. Res. Lett., 35, doi: 10.1029/2008GL035550

  3. Ionic liquids as novel stationary phases in gas liquid chromatography: inverse or normal isotope effect?

    Science.gov (United States)

    Schmarr, Hans-Georg; Slabizki, Petra; Müntnich, Sabrina; Metzger, Carmen; Gracia-Moreno, Elisa

    2012-12-28

    The separation of deuterated and non-deuterated compounds in gas liquid partitioning chromatography (GLC) on silicone type stationary phase usually results in the inverse isotope effect. With ionic liquids (ILs) as stationary phase, however, this may show a totally different nature. The inverse isotope effect, in which heavier (deuterated) isotopic compounds (isotopologues) elute earlier, is to be expected when van der Waals (London) dispersion forces play a dominant role in the solute-stationary phase interaction. Such (apolar) interactions seem to play only a minor role when ILs are the stationary phases, leading to only a marginal inverse isotope effect, e.g. for the separation of 2,4,6-trichloroanisole and its [(2)H(5)]-isotopologue on 1,12-di(tripropylphosphonium) dodecane bis(trifluoromethansulfonyl) amide (commercialized as SLB-IL59, Supelco). Indeed, with the most polar stationary phase available (commercialized as SLB-IL111; Supelco), this separation showed a normal isotope effect. Further examples are presented and the nature of the isotope effect observed is discussed.

  4. Analysis of luwak coffee volatile by using solid phase microextraction and gas chromatography (Analisa senyawa volatil kopi luwak dengan menggunakan mikroekstrasi fase padat dan kromatolgi gas.

    Directory of Open Access Journals (Sweden)

    Ariza Budi Tunjung Sari

    2012-08-01

    Full Text Available The approach to authenticate Luwak coffee is made through analysis of volatile compounds of luwak coffee. Luwak coffee bean from type of arabica obtained from Andungsari Plantation in Bondowoso district, East Java Province Indonesia, was wet processed and sundried prior to roasting step. As many as 120 g green bean was roasted at 170-220°C for 8-12 minutes until reached light brown colour (Agtron scale 65 and was ground prior to extraction. Volatile compounds of roasted Luwak arabica coffee bean were extracted by using solid phase microextraction (SPME at 60°C for 30 minutes. The extracted analyte was subsequently transferred into GC-FID system by splitless injection at 260°C with five minutes sampling time, continued with separation through 50% phenyl 50% dimethylpolysiloxane capillary column and oven temperature programmed from 60°C to 180°C with rate of 5°C/min. Resulted chromatogram shows major peaks mainly in Rt 8.360-9.981, and Rt 9.705-14.778, and minor peaks identified before Rt 10 and after Rt 24. Varied sample quantity ranged within 0.5-2.5 g produced chromatograms which were not significantly different (p=0.08. This research also observed the use of γ-picoline (4-methylpyridine as internal standard. It was showed that γ-picoline appeared at Rt 8.6~ without overlaying other peaks originated from sample. Concentration of γ-picoline at 0.05 μL/g, resulted separable peaks. These findings showed that the use of solid phase microextraction and GC-FID is capable to be apply for identification and quantification of Luwak coffee

  5. Effect of Foam on Liquid Phase Mobility in Porous Media

    Science.gov (United States)

    Eftekhari, A. A.; Farajzadeh, R.

    2017-01-01

    We investigate the validity of the assumption that foam in porous media reduces the mobility of gas phase only and does not impact the liquid-phase mobility. The foam is generated by simultaneous injection of nitrogen gas and a surfactant solution into sandstone cores and its strength is varied by changing surfactant type and concentration. We find, indeed, that the effect of foam on liquid-phase mobility is not pronounced and can be ignored. Our new experimental results and analyses resolve apparent discrepancies in the literature. Previously, some researchers erroneously applied relative permeability relationships measured at small to moderate capillary numbers to foam floods at large capillary number. Our results indicate that the water relative permeability in the absence of surfactant should be measured with the capillary pressure ranging up to values reached during the foam floods. This requires conducting a steady-state gas/water core flood with capillary numbers similar to that of foam floods or measuring the water relative-permeability curve using a centrifuge. PMID:28262795

  6. Activity of Catalyst for Liquid Phase Methanol Synthesis

    Institute of Scientific and Technical Information of China (English)

    WANGYuefa; JanezLevec

    2002-01-01

    The effects of reduction procedure, reaction temperature and composition of feed gas on the activity of a CuO-ZnO-Al2O3 catalyst for liquid phase methanol synthesis were studied. An optimized procedure different from conventional ones was developed to obtain higher activity and better stability of the catalyst. Both CO and CO2 in the feed gas were found to be necessary to maintain the activity of catalyst in the synthesis process. Reaction temperature was limited up to 523K, otherwise the catalyst will be deactivated rapidly. Experimental results show that the catalyst deactivation is caused by sintering and fouling, and the effects of CO and CO2 on the catalyst activity are also investigated. The experimental results indicate that the formation of water in the methanol synthesis is negligible when the feed gas contains both CO and CO2. The mechanism for liquid-phase methanol synthesis was discussed and it differed slightly from that for gas-phase synthesis.

  7. NGNP Process Heat Utilization: Liquid Metal Phase Change Heat Exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Piyush Sabharwall; Mike Patterson; Vivek Utgikar; Fred Gunnerson

    2008-09-01

    One key long-standing issue that must be overcome to fully realize the successful growth of nuclear power is to determine other benefits of nuclear energy apart from meeting the electricity demands. The Next Generation Nuclear Plant (NGNP) will most likely be producing electricity and heat for the production of hydrogen and/or oil retrieval from oil sands and oil shale to help in our national pursuit of energy independence. For nuclear process heat to be utilized, intermediate heat exchange is required to transfer heat from the NGNP to the hydrogen plant or oil recovery field in the most efficient way possible. Development of nuclear reactor - process heat technology has intensified the interest in liquid metals as heat transfer media because of their ideal transport properties. Liquid metal heat exchangers are not new in practical applications. An important rational for considering liquid metals is the potential convective heat transfer is among the highest known. Thus explains the interest in liquid metals as coolant for intermediate heat exchange from NGNP. For process heat it is desired that, intermediate heat exchangers (IHX) transfer heat from the NGNP in the most efficient way possible. The production of electric power at higher efficiency via the Brayton Cycle, and hydrogen production, requires both heat at higher temperatures and high effectiveness compact heat exchangers to transfer heat to either the power or process cycle. Compact heat exchangers maximize the heat transfer surface area per volume of heat exchanger; this has the benefit of reducing heat exchanger size and heat losses. High temperature IHX design requirements are governed in part by the allowable temperature drop between the outlet and inlet of the NGNP. In order to improve the characteristics of heat transfer, liquid metal phase change heat exchangers may be more effective and efficient. This paper explores the overall heat transfer characteristics and pressure drop of the phase change

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

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Paul A. Lessing

    2012-03-01

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

  9. Rapid microwave pyrolysis of coal: methodology and examination of the residual and volatile phases

    Energy Technology Data Exchange (ETDEWEB)

    Monsef-Mirzai, P.; Ravindran, M.; McWhinnie, W.R.; Burchill, P. (Aston University, Birmingham (United Kingdom). Dept. of Chemical Engineering and Applied Chemistry)

    1995-01-01

    Substances such as CuO, Fe[sub 3]O[sub 4] and even metallurgical coke (termed 'receptors') heat rapidly in a microwave oven at 2.45 GHz. The receptor, when mixed with Creswell coal and subjected to microwave radiation, induces rapid pyrolysis of the coal. Condensable tar yields of 20 wt% are obtained with coke, 27 wt% with Fe[sub 3]O[sub 4] and as high as 49 wt% in some experiments with CuO. Despite the high final temperature (1200-1300[degree]C after 3 min), analyses suggest that the volatiles are released in the lower part of the temperature regime but that some secondary cracking does occur. The tars are similar in composition, although with coke the proportion of aromatic hydrogen is greater than with CuO and Fe[sub 3]O[sub 4]. X-ray photoelectron spectroscopy shows that both pyridinic and pyrrolic nitrogen are present in the tars and chars, and that the dominant form of tar sulfur is thiophenic. There is evidence that mineral sulfur is immobilized when CuO in particular is the receptor. The chars formed show a degree of graphitization and are themselves excellent microwave receptors. In the presence of oxide receptors, char-oxide redox reactions occur, with loss of char, reduction of oxide and enhanced yields of CO and CO[sub 2]. Of the lighter hydrocarbons identified in the gas phase, methane predominates. The data obtained are compared with those for other pyrolysis methods. 22 refs., 1 fig., 9 tabs.

  10. Controlling the volatility of the written optical state in electrochromic DNA liquid crystals

    NARCIS (Netherlands)

    Liu, Kai; Varghese, Justin; Gerasimov, Jennifer Y.; Polyakov, Alexey O.; Shuai, Min; Su, Juanjuan; Chen, Dong; Zajaczkowski, Wojciech; Marcozzi, Alessio; Pisula, Wojciech; Noheda, Beatriz; Palstra, Thomas T. M.; Clark, Noel A.; Herrmann, Andreas

    Liquid crystals are widely used in displays for portable electronic information display. To broaden their scope for other applications like smart windows and tags, new material properties such as polarizer-free operation and tunable memory of a written state become important. Here, we describe an

  11. DETERMINATION AND CLASSIFICATION OF VOLATILE COMPOUNDS OF PASTIRMA USING SOLID PHASE MICROEXTRACTION/GAS CHROMATOGRAPHY/MASS SPECTROMETRY

    Directory of Open Access Journals (Sweden)

    Eda Demirok

    2013-10-01

    Full Text Available Pastırma, a traditional dry cured Turkish meat product, has a great number of specific aroma compounds, which occur as a result of lipid oxidation, protein degradation and formulation of çemen paste. These compounds give characteristic flavor to pastırma and the main objective of this study was to determine the nature of these compounds. Fifty-eight volatile compounds, grouped into nine chemical classes were identified using solid phase microextraction technique (SPME coupled to gas chromatography/mass spectrometry (GC-MS. Aldehydes, mostly lipid oxidation products, were determined as the major chemical group, representing 17.54-78.02% of total volatile compounds. The major volatile aldehyde was hexanal (2.36-55.41%, followed by 2-methyl-2-butenal (0.97-14.69% and then heptanal (0.29-4.77%. Sulfur compounds possibly derived from spices or formed by proteolysis of sulfur-containing amino acids, were the second most abundant group, with concentrations ranging between 6.04 and 50.60%. Other important volatile compounds of pastırma were aliphatic hydrocarbons, aromatic ketones, hydrocarbons, esters, alcohols, acids, terpenes, and furans.

  12. Comparison of liquid and supercritical fluid chromatography mobile phases for enantioselective separations on polysaccharide stationary phases.

    Science.gov (United States)

    Khater, Syame; Lozac'h, Marie-Anne; Adam, Isabelle; Francotte, Eric; West, Caroline

    2016-10-07

    Analysis and production of enantiomerically pure compounds is a major topic of interest when active pharmaceutical ingredients are concerned. Enantioselective chromatography has become a favourite both at the analytical and preparative scales. High-performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC) are dominating the scene and are often seen as complementary techniques. Nowadays, for economic and ecologic reasons, SFC may be preferred over normal-phase HPLC (NPLC) as it allows significant reductions in solvent consumption. However, the transfer of NPLC methods to SFC is not always straightforward. In this study, we compare the retention of achiral molecules and separation of enantiomers under supercritical fluid (carbon dioxide with ethanol or isopropanol) and liquid normal-phase (heptane with ethanol or isopropanol) elution modes with polysaccharide stationary phases in order to explore the differences between the retention and enantioseparation properties between the two modes. Chemometric methods (namely quantitative structure-retention relationships and discriminant analysis) are employed to compare the results obtained on a large set of analytes (171 achiral probes and 97 racemates) and gain some understanding on the retention and separation mechanisms. The results indicate that, contrary to popular belief, carbon dioxide - solvent SFC mobile phases are often weaker eluents than liquid mobile phases. It appears that SFC and NPLC elution modes provide different retention mechanisms. While some enantioseparations are unaffected, facilitating the transfer between the two elution modes, other enantioseparations may be drastically different due to different types and strength of interactions contributing to enantioselectivity.

  13. Investigating materials formation with liquid-phase and cryogenic TEM

    Science.gov (United States)

    de Yoreo, J. J.; N. A. J. M., Sommerdijk

    2016-08-01

    The recent advent of liquid-phase transmission electron microscopy (TEM) and advances in cryogenic TEM are transforming our understanding of the physical and chemical mechanisms underlying the formation of materials in synthetic, biological and geochemical systems. These techniques have been applied to study the dynamic processes of nucleation, self-assembly, crystal growth and coarsening for metallic and semiconductor nanoparticles, (bio)minerals, electrochemical systems, macromolecular complexes, and organic and inorganic self-assembling systems. New instrumentation and methodologies that are currently on the horizon promise new opportunities for advancing the science of materials synthesis.

  14. Flow Rate of He Ⅱ Liquid-Vapor Phase Separator

    Institute of Scientific and Technical Information of China (English)

    Xingen YU; Qing LI; Qiang LI; Zhengyu LI

    2005-01-01

    Experimental results are presented for superfluld (He Ⅱ) flow through porous plug liquid-vapor phase separators.Tests have been performed on seven porous plugs with different thicknesses or different permeabilities. The temperature was measured from 1.5K to 1.9K. Two flow regions were observed in small and large pressure and temperature differences regions respectively. The experimental data are compared with theoretical predictions.The performance and applicability of the basic theory are discussed. Hysteresis of the flow rate is also observed and discussed.

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

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-05-01

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

  16. Liquid-Phase Processing of Barium Titanate Thin Films

    Science.gov (United States)

    Harris, David Thomas

    Processing of thin films introduces strict limits on the thermal budget due to substrate stability and thermal expansion mismatch stresses. Barium titanate serves as a model system for the difficulty in producing high quality thin films because of sensitivity to stress, scale, and crystal quality. Thermal budget restriction leads to reduced crystal quality, density, and grain growth, depressing ferroelectric and nonlinear dielectric properties. Processing of barium titanate is typically performed at temperatures hundreds of degrees above compatibility with metalized substrates. In particular integration with silicon and other low thermal expansion substrates is desirable for reductions in costs and wider availability of technologies. In bulk metal and ceramic systems, sintering behavior has been encouraged by the addition of a liquid forming second phase, improving kinetics and promoting densification and grain growth at lower temperatures. This approach is also widespread in the multilayer ceramic capacitor industry. However only limited exploration of flux processing with refractory thin films has been performed despite offering improved dielectric properties for barium titanate films at lower temperatures. This dissertation explores physical vapor deposition of barium titanate thin films with addition of liquid forming fluxes. Flux systems studied include BaO-B2O3, Bi2O3-BaB2O 4, BaO-V2O5, CuO-BaO-B2O3, and BaO-B2O3 modified by Al, Si, V, and Li. Additions of BaO-B2O3 leads to densification and an increase in average grain size from 50 nm to over 300 nm after annealing at 900 °C. The ability to tune permittivity of the material improved from 20% to 70%. Development of high quality films enables engineering of ferroelectric phase stability using residual thermal expansion mismatch in polycrystalline films. The observed shifts to TC match thermodynamic calculations, expected strain from the thermal expansion coefficients, as well as x-ray diffract measurements

  17. Molecular simulation studies of reversed-phase liquid chromatography.

    Science.gov (United States)

    Lindsey, Rebecca K; Rafferty, Jake L; Eggimann, Becky L; Siepmann, J Ilja; Schure, Mark R

    2013-04-26

    Over the past 20 years, molecular simulation methods have been applied to the modeling of reversed-phase liquid chromatography (RPLC). The purpose of these simulations was to provide a molecular-level understanding of: (i) the structure and dynamics of the bonded phase and its interface with the mobile phase, (ii) the interactions of analytes with the bonded phase, and (iii) the retention mechanism for different analytes. However, the investigation of chromatographic systems poses significant challenges for simulations with respect to the accuracy of the molecular mechanics force fields and the efficiency of the sampling algorithms. This review discusses a number of aspects concerning molecular simulation studies of RPLC systems including the historical development of the subject, the background needed to understand the two prevalent techniques, molecular dynamics (MD) and Monte Carlo (MC) methods, and the wealth of insight provided by these simulations. Examples from the literature employing MD approaches and from the authors' laboratory using MC methods are discussed. The former can provide information on chain dynamics and transport properties, whereas the latter techniques are uniquely suited for the investigation of phase and sorption equilibria that underly RPLC retention, and both can be used to elucidate the bonded-chain conformations and solvent distributions. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Determination of volatile components of saffron by optimised ultrasound-assisted extraction in tandem with dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometry.

    Science.gov (United States)

    Sereshti, Hassan; Heidari, Reza; Samadi, Soheila

    2014-01-15

    In the present research, a combined extraction method of ultrasound-assisted extraction (UAE) in conjunction with dispersive liquid-liquid microextraction (DLLME) was applied to isolation and enrichment of saffron volatiles. The extracted components of the saffron were separated and determined by gas chromatography-mass spectrometry (GC-MS) technique. The mixture of methanol/acetonitrile was chosen for the extraction of the compounds and chloroform was used at the preconcentration stage. The important parameters, such as composition of extraction solvent, volume of preconcentration solvent, ultrasonic applying time, and salt concentration were optimised by using a half-fraction factorial central composite design (CCD). Under the optimal conditions, the linear dynamic ranges (LDRs) were 10-10,000mgL(-)(1). The determination coefficients (R(2)) were from 0.9990 to 0.9997. The limits of detection (LODs) and limits of quantification (LOQs) for the extracted compounds were 6-123mgL(-)(1) and 20-406mgL(-)(1), respectively. The relative standard deviations (RSDs) were 2.48-9.82% (n=3). The enhancement factors (EFs) were 3.6-41.3.

  19. Effect of liquid distribution on gas-water phase mass transfer in an unsaturated sand during infiltration

    Science.gov (United States)

    Imhoff, Paul T.; Jaffé, Peter R.

    1994-09-01

    Gas-water phase mass transfer was examined in a homogeneous sand with both the gas and water phase mobile: water was infiltrated from the top of the sand column while benzene-laden air flowed upward from the bottom. Mass-transfer limitations for this situation may be important for applications of bioventing, where water and nutrients are added at the ground surface simultaneously with induced air movement to carry oxygen and volatile organics to microbial populations. Gas- and water-phase samples indicate that gas-water phase mass transfer was sufficiently fast that equilibrium between gas and water phases was achieved at all sampling locations within the porous medium. Lower-bound estimates for the gas-water mass-transfer rate coefficient show that mass transfer was at least 10-40 times larger than predictions made from an empirical model developed for gas-water phase mass transfer in an identical porous medium. A water-phase tracer test demonstrates that water flow was much more uniform in this study than in those earlier experiments, which is a likely explanation for the differing rates of gas-water phase mass transfer. It is hypothesized that the liquid distribution in previous laboratory experiments was less uniform because of preferential flow paths due to wetting front instabilities. Gas-water phase mass-transfer rate coefficients reported in this investigation are for an ideal situation of uniform water infiltration: mass-transfer rates in field soils are expected to be significantly smaller.

  20. The effect of the interaction between the minority phase droplets on the nucleation behavior during the liquid-liquid phase transformation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The microstructure evolution during the liquid-liquid phase transformation of Al-Pb alloy was calculated. The numerical results indicate that the interaction between the minority phase droplets has effect on the nucleation process of the droplets, and the effect increases with the cooling rate and the content of Pb.

  1. Liquid-liquid phase separation in aerosol particles: Imaging at the Nanometer Scale

    Energy Technology Data Exchange (ETDEWEB)

    O' Brien, Rachel; Wang, Bingbing; Kelly, Stephen T.; Lundt, Nils; You, Yuan; Bertram, Allan K.; Leone, Stephen R.; Laskin, Alexander; Gilles, Mary K.

    2015-04-21

    Atmospheric aerosols can undergo phase transitions including liquid-liquid phase separation (LLPS) while responding to changes in the ambient relative humidity (RH). Here, we report results of chemical imaging experiments using environmental scanning electron microscopy (ESEM) and scanning transmission x-ray microscopy (STXM) to investigate the LLPS of micron sized particles undergoing a full hydration-dehydration cycle. Internally mixed particles composed of ammonium sulfate (AS) and either: limonene secondary organic carbon (LSOC), a, 4-dihydroxy-3-methoxybenzeneaceticacid (HMMA), or polyethylene glycol (PEG-400) were studied. Events of LLPS with apparent core-shell particle morphology were observed for all samples with both techniques. Chemical imaging with STXM showed that both LSOC/AS and HMMA/AS particles were never homogeneously mixed for all measured RH’s above the deliquescence point and that the majority of the organic component was located in the shell. The shell composition was estimated as 65:35 organic: inorganic in LSOC/AS and as 50:50 organic: inorganic for HMMA/AS. PEG-400/AS particles showed fully homogeneous mixtures at high RH and phase separated below 89-92% RH with an estimated 50:50% organic to inorganic mix in the shell. These two chemical imaging techniques are well suited for in-situ analysis of the hygroscopic behavior, phase separation, and surface composition of collected ambient aerosol particles.

  2. Volume phase transitions of cholesteric liquid crystalline gels

    Energy Technology Data Exchange (ETDEWEB)

    Matsuyama, Akihiko, E-mail: matuyama@bio.kyutech.ac.jp [Department of Bioscience and Bioinformatics, Faculty of Computer Science and Systems Engineering, Kyushu Institute of Technology, Kawazu 680-4, Iizuka, Fukuoka 820-8502 (Japan)

    2015-05-07

    We present a mean field theory to describe anisotropic deformations of a cholesteric elastomer without solvent molecules and a cholesteric liquid crystalline gel immersed in isotropic solvents at a thermal equilibrium state. Based on the neoclassical rubber theory of nematic elastomers, we derive an elastic energy and a twist distortion energy, which are important to determine the shape of a cholesteric elastomer (or gel). We demonstrate that when the elastic energy dominates in the free energy, the cholesteric elastomer causes a spontaneous compression in the pitch axis and elongates along the director on the plane perpendicular to the pitch axis. Our theory can qualitatively describe the experimental results of a cholesteric elastomer. We also predict the first-order volume phase transitions and anisotropic deformations of a gel at the cholesteric-isotropic phase transition temperature. Depending on a chirality of a gel, we find a prolate or oblate shape of cholesteric gels.

  3. Influences of misfit strains on liquid phase heteroepitaxial growth

    Science.gov (United States)

    Lu, Yanli; Peng, Yingying; Yu, Genggeng; Chen, Zheng

    2017-10-01

    Influences of misfit strains with different signs on liquid phase heteroepitaxial growth are studied by binary phase field crystal model. It is amazing to find that double islands are formed because of lateral and vertical separation. The morphological evolution of epitaxial layer depends on signs of misfit strains. The maximum atomic layer thickness of double islands under negative misfit strain is larger than that of under positive misfit strain at the same evolutional time, and size differences between light and dark islands is much smaller under negative misfit strain than that of under positive misfit strain. In addition, concentration field and density field approximately have similar variational law along x direction under the same misfit strain but show opposite variational trend under misfit strains with different signs. Generally, free energy of epitaxial growth systems keeps similar variational trend under misfit strains with different signs.

  4. Olefin Epoxidation in Aqueous Phase Using Ionic-Liquid Catalysts.

    Science.gov (United States)

    Cokoja, Mirza; Reich, Robert M; Wilhelm, Michael E; Kaposi, Marlene; Schäffer, Johannes; Morris, Danny S; Münchmeyer, Christian J; Anthofer, Michael H; Markovits, Iulius I E; Kühn, Fritz E; Herrmann, Wolfgang A; Jess, Andreas; Love, Jason B

    2016-07-21

    Hydrophobic imidazolium-based ionic liquids (IL) act as catalysts for the epoxidation of unfunctionalized olefins in water using hydrogen peroxide as oxidant. Although the catalysts are insoluble in both the substrate and in water, surprisingly, they are very well soluble in aqueous H2 O2 solution, owing to perrhenate-H2 O2 interactions. Even more remarkably, the presence of the catalyst also boosts the solubility of substrate in water. This effect is crucially dependent on the cation design. Hence, the imidazolium perrhenates enable both the transfer of hydrophobic substrate into the aqueous phase, and serve as actual catalysts, which is unprecedented. At the end of the reaction and in absence of H2 O2 the IL catalyst forms a third phase next to the lipophilic product and water and can easily be recycled.

  5. Reversible Nanoparticle Cubic Lattices in Blue Phase Liquid Crystals.

    Science.gov (United States)

    Gharbi, Mohamed Amine; Manet, Sabine; Lhermitte, Julien; Brown, Sarah; Milette, Jonathan; Toader, Violeta; Sutton, Mark; Reven, Linda

    2016-03-22

    Blue phases (BPs), a distinct class of liquid crystals (LCs) with 3D periodic ordering of double twist cylinders involving orthogonal helical director twists, have been theoretically studied as potential templates for tunable colloidal crystals. Here, we report the spontaneous formation of thermally reversible, cubic crystal nanoparticle (NP) assemblies in BPs. Gold NPs, functionalized to be highly miscible in cyanobiphenyl-based LCs, were dispersed in BP mixtures and characterized by polarized optical microscopy and synchrotron small-angle X-ray scattering (SAXS). The NPs assemble by selectively migrating to periodic strong trapping sites in the BP disclination lines. The NP lattice, remarkably robust given the small particle size (4.5 nm diameter), is commensurate with that of the BP matrix. At the BP I to BP II phase transition, the NP lattice reversibly switches between two different cubic structures. The simultaneous presence of two different symmetries in a single material presents an interesting opportunity to develop novel dynamic optical materials.

  6. Espresso coffee foam delays cooling of the liquid phase.

    Science.gov (United States)

    Arii, Yasuhiro; Nishizawa, Kaho

    2017-04-01

    Espresso coffee foam, called crema, is known to be a marker of the quality of espresso coffee extraction. However, the role of foam in coffee temperature has not been quantitatively clarified. In this study, we used an automatic machine for espresso coffee extraction. We evaluated whether the foam prepared using the machine was suitable for foam analysis. After extraction, the percentage and consistency of the foam were measured using various techniques, and changes in the foam volume were tracked over time. Our extraction method, therefore, allowed consistent preparation of high-quality foam. We also quantitatively determined that the foam phase slowed cooling of the liquid phase after extraction. High-quality foam plays an important role in delaying the cooling of espresso coffee.

  7. Three-phase slug flow in microchips can provide beneficial reaction conditions for enzyme liquid-liquid reactions.

    Science.gov (United States)

    Cech, Jiří; Přibyl, Michal; Snita, Dalimil

    2013-01-01

    Here, we introduce a solution to low stability of a two-phase slug flow with a chemical reaction occurring at the phase interface in a microfluidic reactor where substantial merging of individual reacting slugs results in the loss of uniformity of the flow. We create a three-phase slug flow by introducing a third fluid phase into the originally two-phase liquid-liquid slug flow, which generates small two-phase liquid slugs separated by gas phase. Introduction of the third phase into our system efficiently prevents merging of slugs and provides beneficial reaction conditions, such as uniform flow pattern along the whole reaction capillary, interfacial area with good reproducibility, and intensive water-oil interface renewal. We tested the three-phase flow on an enzyme hydrolysis of soybean oil and compared the reaction conversion with those from unstable two-phase slug flows. We experimentally confirmed that the three-phase slug flow arrangement provides conversions and pressure drops comparable or even better with two-phase liquid-liquid arrangements.

  8. Experimental investigation of bioethanol liquid phase dehydration using natural clinoptilolite.

    Science.gov (United States)

    Karimi, Samira; Ghobadian, Barat; Omidkhah, Mohammad-Reza; Towfighi, Jafar; Tavakkoli Yaraki, Mohammad

    2016-05-01

    An experimental study of bioethanol adsorption on natural Iranian clinoptilolite was carried out. Dynamic breakthrough curves were used to investigate the best adsorption conditions in bioethanol liquid phase. A laboratory setup was designed and fabricated for this purpose. In order to find the best operating conditions, the effect of liquid pressure, temperature and flow rate on breakthrough curves and consequently, maximum ethanol uptake by adsorbent were studied. The effects of different variables on final bioethanol concentration were investigated using Response Surface Methodology (RSM). The results showed that by working at optimum condition, feed with 96% (v/v) initial ethanol concentration could be purified up to 99.9% (v/v). In addition, the process was modeled using Box-Behnken model and optimum operational conditions to reach 99.9% for final ethanol concentration were found equal to 10.7 °C, 4.9 bar and 8 mL/min for liquid temperature, pressure and flow rate, respectively. Therefore, the selected natural Iranian clinoptilolite was found to be a promising adsorbent material for bioethanol dehydration process.

  9. Vapor-liquid (VLE) and liquid-liquid (LLE) phase equilibria calculations for polystyrene plus methyleyclohexane and polystyrene plus cyclohexane solutions

    DEFF Research Database (Denmark)

    Wilczura-Wachnik, H.; Jonsdottir, Svava Osk

    2006-01-01

    This paper presents the vapor-liquid (VLE) and liquid-liquid (LLE) phase equilibria predictions for polystyrene in two theta solvents: cyclohexane and methylcyclohexane. VLE calculations were performed with the Elbro free volume method and a modified version of the PC-SAFT method, as well...

  10. Application of Ionic Liquids in High Performance Reversed-Phase Chromatography

    Science.gov (United States)

    Wang, Ye; Tian, Minglei; Bi, Wentao; Row, Kyung Ho

    2009-01-01

    Ionic liquids, considered “green” chemicals, are widely used in many areas of analytical chemistry due to their unique properties. Recently, ionic liquids have been used as a kind of novel additive in separation and combined with silica to synthesize new stationary phase as separation media. This review will focus on the properties and mechanisms of ionic liquids and their potential applications as mobile phase modifier and surface-bonded stationary phase in reversed-phase high performance liquid chromatography (RP-HPLC). Ionic liquids demonstrate advantages and potential in chromatographic field. PMID:19582220

  11. Application of Ionic Liquids in High Performance Reversed-Phase Chromatography

    Directory of Open Access Journals (Sweden)

    Wentao Bi

    2009-06-01

    Full Text Available Ionic liquids, considered “green” chemicals, are widely used in many areas of analytical chemistry due to their unique properties. Recently, ionic liquids have been used as a kind of novel additive in separation and combined with silica to synthesize new stationary phase as separation media. This review will focus on the properties and mechanisms of ionic liquids and their potential applications as mobile phase modifier and surface-bonded stationary phase in reversed-phase high performance liquid chromatography (RP-HPLC. Ionic liquids demonstrate advantages and potential in chromatographic field.

  12. Determination of Stabiliser Contents in Advanced Gun Propellants by Reverse Phase High Performance Liquid Chromatography

    Science.gov (United States)

    1994-03-01

    HIGH PERFORMANCE LIQUID CHROMATOGRAPHY N"m A.R. TURNER AND A. WHITE...TO biEPROOU.; AND SELL THIS REPORT Determination of Stabiliser Contents in Advanced Gun Propellants by Reverse Phase High Performance Liquid Chromatography A.R...8217/......... .. Availability Cooes Dist Avaiardlo A-i Determination of Stabiliser Contents in Advanced Gun Propellants by Reverse Phase High Performance Liquid Chromatography

  13. Comparison of simultaneous distillation extraction and solid-phase micro-extraction for determination of volatile constituents in tobacco flavor

    Institute of Scientific and Technical Information of China (English)

    ZHONG Ke-jun; WEI Wan-zhi; GUO Fang-qiu; HUANG Lan-fang

    2005-01-01

    The volatile and semi-volatile components in tobacco flavor additives were extracted by both simultaneous distillation extraction and solid-phase micro-extraction. Extraction conditions for solid-phase micro-extraction were optimized with information theory. Then, detection were accomplished by gas chromatography-mass spectrometry. Characteristic of each method was compared. Qualitative analysis and quantitative analysis of 6# tobacco flavor sample were accomplished through both simultaneous distillation extraction and solid-phase micro-extraction. The experimental results show that solid-phase micro-extraction method is the first choice for qualitative analysis and simultaneous distillation extraction is another good selection for quantitative analysis. By means of simultaneous distillation extraction, 20 components are identified, accounting for 92.77% of the total peak areas. Through solid-phase micro-extraction, there are 17 components identified accounting for 91.49% of the total peak areas. The main aromatic components in 6# tobacco flavor sample are propanoic acid, 2-hydroxy-, ethyl ester, menthol and menthyl acetate. The presented method has been successfully used for quality control of tobacco flavor.

  14. Dynamic headspace time-extended helix liquid-phase microextraction.

    Science.gov (United States)

    Huang, Shih-Pin; Chen, Pai-Shan; Huang, Shang-Da

    2009-05-15

    Liquid-phase microextraction (LPME) has been proved to be a fast, inexpensive and effective sample pre-treatment technique for the analyses of pesticides and many other compounds. In this investigation, a new headspace microextraction technique, dynamic headspace time-extended helix liquid-phase microextraction (DHS-TEH-LPME), is presented. In this work, use of a solvent cooling system, permits the temperature of the extraction solvent to be lowered. Lowering the temperature of the extraction solvent not only reduces solvent loss but also extends the feasible extraction time, thereby improving extraction efficiency. Use of a larger volume of the solvent not only extends the feasible extraction time but also, after extraction, leaves a larger volume to be directly injected into the gas chromatography (GC) to increase extraction efficiency and instrument signal. The DHS-TEH-LPME technique was used to extract six organochlorine pesticides (OCPs) from 110ml water samples that had been spiked with the analytes at ng/l levels, and stirred for 60min. The proposed method attained enrichments up to 2121 fold. The effects of extraction solvent identity, sample agitation, extraction time, extraction temperature, and salt concentration on extraction performance were also investigated. The method detection limits (MDLs) varied from 0.2 to 25ng/l. The calibration curves were linear for at least 2 orders of magnitude with R(2)>==0.996. Relative recoveries in river water were more than 86%.

  15. Comparing two tetraalkylammonium ionic liquids. II. Phase transitions

    Science.gov (United States)

    Lima, Thamires A.; Paschoal, Vitor H.; Faria, Luiz F. O.; Ribeiro, Mauro C. C.; Ferreira, Fabio F.; Costa, Fanny N.; Giles, Carlos

    2016-06-01

    Phase transitions of the ionic liquids n-butyl-trimethylammonium bis(trifluoromethanesulfonyl)imide, [N1114][NTf2], and methyl-tributylammonium bis(trifluoromethanesulfonyl)imide, [N1444][NTf2], were investigated by differential scanning calorimetry (DSC), X-ray diffraction (XRD) measurements, and Raman spectroscopy. XRD and Raman spectra were obtained as a function of temperature at atmospheric pressure, and also under high pressure at room temperature using a diamond anvil cell (DAC). [N1444][NTf2] experiences glass transition at low temperature, whereas [N1114][NTf2] crystallizes or not depending on the cooling rate. Both the ionic liquids exhibit glass transition under high pressure. XRD and low-frequency Raman spectra provide a consistent physical picture of structural ordering-disordering accompanying the thermal events of crystallization, glass transition, cold crystallization, pre-melting, and melting. Raman spectra in the high-frequency range of some specific cation and anion normal modes reveal conformational changes of the molecular structures along phase transitions.

  16. The ionic liquid isopropylammonium formate as a mobile phase modifier to improve protein stability during reversed phase liquid chromatography.

    Science.gov (United States)

    Zhou, Ling; Danielson, Neil D

    2013-12-01

    The room temperature ionic liquid isopropylammonium formate (IPAF) is studied as a reversed phase HPLC mobile phase modifier for separation of native proteins using a polymeric column and the protein stability is compared to that using acetonitrile (MeCN) as the standard organic mobile phase modifier. A variety of important proteins with different numbers of subunits are investigated, including non-subunit proteins: albumin, and amyloglucosidase (AMY); a two subunit protein: thyroglobulin (THY); and four subunit proteins: glutamate dehydrogenase (GDH) and lactate dehydrogenase (LDH). A significant enhancement in protein stability is observed in the chromatograms upon using IPAF as a mobile phase modifier. The first sharper peak at about 2min represented protein in primarily the native form and a second broader peak more retained at about 5-6min represented substantially denatured or possibly aggregated protein. The investigated proteins (except LDH) could maintain the native form within up to 50% IPAF, while a mobile phase, with as low as 10% MeCN, induced protein denaturation. The assay for pyruvate using LDH has further shown that enzymatic activity can be maintained up to 30% IPAF in water in contrast to no activity using 30% MeCN.

  17. Liquid-liquid phase separation in solutions of ionic liquids: phase diagrams, corresponding state analysis and comparison with simulations of the primitive model

    Energy Technology Data Exchange (ETDEWEB)

    Schroeer, W; Vale, V R, E-mail: schroer@uni-bremen.d [Institut fuer Anorganische und Physikalische Chemie, Fachbereich Biologie-Chemie, Universitaet Bremen, D-28359 Bremen (Germany)

    2009-10-21

    Phase diagrams of ionic solutions of the ionic liquid C{sub 18}mim{sup +}NTF{sub 2}{sup -} (1-n-octadecyl-3-methyl imidazolium bistrifluormethylsulfonylimide) in decalin, cyclohexane and methylcyclohexane are reported and compared with that of solutions of other imidazolium ionic liquids with the anions NTF{sub 2}{sup -}, Cl{sup -} and BF4{sup -} in arenes, CCl{sub 4}, alcohols and water. The phase diagrams are analysed presuming Ising criticality and taking into account the asymmetry of the phase diagrams. The resulting parameters are compared with simulation results for equal-sized charged hard spheres in a dielectric continuum, the restricted primitive model (RPM) and the primitive model (PM) that allows for ions of different size. In the RPM temperature scale the critical temperatures vary almost linearly with the dielectric permittivity of the solvent. The RPM critical temperatures of the solutions in non-polar solvents are very similar, somewhat below the RPM value. Correlations with the boiling temperatures of the solvents and a dependence on the length of the side chain of the imidazolium cations show that dispersion interactions modify the phase transition, which is mainly determined by Coulomb forces. Critical concentrations, widths of the phase diagrams and the slopes of the diameter are different for the solutions in protic and aprotic solvents. The phase diagrams of the solutions in alcohols and water get a lower critical solution point when represented in RPM variables.

  18. Liquid-liquid phase separation in solutions of ionic liquids: phase diagrams, corresponding state analysis and comparison with simulations of the primitive model.

    Science.gov (United States)

    Schröer, W; Vale, V R

    2009-10-21

    Phase diagrams of ionic solutions of the ionic liquid C(18)mim(+)NTF(2)(-) (1-n-octadecyl-3-methyl imidazolium bistrifluormethylsulfonylimide) in decalin, cyclohexane and methylcyclohexane are reported and compared with that of solutions of other imidazolium ionic liquids with the anions NTF(2)(-), Cl(-) and BF4(-) in arenes, CCl(4), alcohols and water. The phase diagrams are analysed presuming Ising criticality and taking into account the asymmetry of the phase diagrams. The resulting parameters are compared with simulation results for equal-sized charged hard spheres in a dielectric continuum, the restricted primitive model (RPM) and the primitive model (PM) that allows for ions of different size. In the RPM temperature scale the critical temperatures vary almost linearly with the dielectric permittivity of the solvent. The RPM critical temperatures of the solutions in non-polar solvents are very similar, somewhat below the RPM value. Correlations with the boiling temperatures of the solvents and a dependence on the length of the side chain of the imidazolium cations show that dispersion interactions modify the phase transition, which is mainly determined by Coulomb forces. Critical concentrations, widths of the phase diagrams and the slopes of the diameter are different for the solutions in protic and aprotic solvents. The phase diagrams of the solutions in alcohols and water get a lower critical solution point when represented in RPM variables.

  19. Phase diagrams and kinetics of solid-liquid phase transitions in crystalline polymer blends

    Science.gov (United States)

    Matkar, Rushikesh A.

    A free energy functional has been formulated based on an order parameter approach to describe the competition between liquid-liquid phase separation and solid-liquid phase separation. In the free energy description, the assumption of complete solvent rejection from the crystalline phase that is inherent in the Flory diluent theory was removed as solvent has been found to reside in the crystalline phase in the form of intercalates. Using this approach, we have calculated various phase diagrams in binary blends of crystalline and amorphous polymers that show upper or lower critical solution temperature. Also, the discrepancy in the chi values obtained from different experimental methods reported in the literature for the polymer blend of poly(vinylidenefluoride) and poly(methylmethacrylate) has been discussed in the context of the present model. Experimental phase diagram for the polymer blend of poly(caprolactone) and polystyrene has also been calculated. Of particular importance is that the crystalline phase concentration as a function of temperature has been calculated using free energy minimization methods instead of assuming it to be pure. In the limit of complete immiscibility of the solvent in the crystalline phase, the Flory diluent theory is recovered. The model is extended to binary crystalline blends and the formation of eutectic, peritectic and azeotrope phase diagrams has been explained on the basis of departure from ideal solid solution behavior. Experimental eutectic phase diagram from literature of a binary blend of crystalline polymer poly(caprolactone) and trioxane were recalculated using the aforementioned approach. Furthermore, simulations on the spatio temporal dynamics of crystallization in blends of crystalline and amorphous polymers were carried out using the Ginzburg-Landau approach. These simulations have provided insight into the distribution of the amorphous polymer in the blends during the crystallization process. The simulated results

  20. Liquid-Liquid Phase Equilibria and Interactions between Droplets in Water-in-Oil Microemulsions.

    Science.gov (United States)

    Yin, Tianxiang; Wang, Mingjie; Tao, Xiaoyi; Shen, Weiguo

    2016-12-20

    The liquid-liquid phase equilibria of [water/sodium bis(2-ethylhexyl)sulfosuccinate (AOT)/n-decane] with the molar ratio w0 of water to AOT being 37.9 and [water/AOT/ethoxylated-2,5,8,11-tetramethyl-6-dodecyne-5,8-diol(Dynol-604)/n-decane] with w0 = 37.9 and the mole fraction α of Dynol-604 in the total surfactants being 0.158 were measured in this study. From the data collected in the critical region, the critical exponent β corresponding to the width of the coexistence curve was determined, which showed good agreement with the 3D-Ising value. A thermodynamic approach based on the Carnahan-Starling-van der Waals type equation was proposed to describe the coexistence curves and to deduce the interaction properties between droplets in the microemulsions. The interaction enthalpies were found to be positive for the studied systems, which evidenced that the entropy effect dominated the phase separations as the temperature increased. The addition of Dynol-604 into the (water/AOT/n-decane) microemulsion resulted in the decrease in the critical temperature and the interaction enthalpy. Combining the liquid-liquid equilibrium data for (water/AOT/n-decane) microemulsions with various w0 values determined previously, it was shown that the interaction enthalpy decreased with w0 and tended to change its sign at low w0, which coincided with the results from the isothermal titration calorimetry investigation. All of these behaviors were interpreted by the effects of entropy and enthalpy and their competition, which resulted from the release of solvent molecules entrapped in the interface of microemulsion droplets and were dependent on the rigidity of the surfactant layers and the size of the droplet.

  1. Comparison of electrical and optical characteristics in gas-phase and gas-liquid phase discharges

    Science.gov (United States)

    Qazi, H. I. A.; Nie, Qiu-Yue; Li, He-Ping; Zhang, Xiao-Fei; Bao, Cheng-Yu

    2015-12-01

    This paper presents an AC-excited argon discharge generated using a gas-liquid (two-phase) hybrid plasma reactor, which mainly consists of a powered needle electrode enclosed in a conical quartz tube and grounded deionized water electrode. The discharges in the gas-phase, as well as in the two-phase, exhibit two discharge modes, i.e., the low current glow-like diffuse mode and the high current streamer-like constrict mode, with a mode transition, which exhibits a negative resistance of the discharges. The optical emission spectral analysis shows that the stronger diffusion of the water vapor into the discharge region in the two-phase discharges boosts up the generation of OH (A-X) radicals, and consequently, leads to a higher rotational temperature in the water-phase plasma plume than that of the gas-phase discharges. Both the increase of the power input and the decrease of the argon flow rate result in the increase of the rotational temperature in the plasma plume of the water-phase discharge. The stable two-phase discharges with a long plasma plume in the water-phase under a low power input and gas flow rate may show a promising prospect for the degradation of organic pollutants, e.g., printing and dyeing wastewater, in the field of environmental protection.

  2. Comparison of electrical and optical characteristics in gas-phase and gas-liquid phase discharges

    Energy Technology Data Exchange (ETDEWEB)

    Qazi, H. I. A.; Li, He-Ping, E-mail: liheping@tsinghua.edu.cn; Zhang, Xiao-Fei; Bao, Cheng-Yu [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Nie, Qiu-Yue [School of Electrical Engineering and Automation, Harbin Institute of Technology, Harbin, Heilongjiang Province 150001 (China)

    2015-12-15

    This paper presents an AC-excited argon discharge generated using a gas-liquid (two-phase) hybrid plasma reactor, which mainly consists of a powered needle electrode enclosed in a conical quartz tube and grounded deionized water electrode. The discharges in the gas-phase, as well as in the two-phase, exhibit two discharge modes, i.e., the low current glow-like diffuse mode and the high current streamer-like constrict mode, with a mode transition, which exhibits a negative resistance of the discharges. The optical emission spectral analysis shows that the stronger diffusion of the water vapor into the discharge region in the two-phase discharges boosts up the generation of OH (A–X) radicals, and consequently, leads to a higher rotational temperature in the water-phase plasma plume than that of the gas-phase discharges. Both the increase of the power input and the decrease of the argon flow rate result in the increase of the rotational temperature in the plasma plume of the water-phase discharge. The stable two-phase discharges with a long plasma plume in the water-phase under a low power input and gas flow rate may show a promising prospect for the degradation of organic pollutants, e.g., printing and dyeing wastewater, in the field of environmental protection.

  3. Magnetic ionic liquid aqueous two-phase system coupled with high performance liquid chromatography: A rapid approach for determination of chloramphenicol in water environment.

    Science.gov (United States)

    Yao, Tian; Yao, Shun

    2017-01-20

    A novel organic magnetic ionic liquid based on guanidinium cation was synthesized and characterized. A new method of magnetic ionic liquid aqueous two-phase system (MILATPs) coupled with high-performance liquid chromatography (HPLC) was established to preconcentrate and determine trace amount of chloramphenicol (CAP) in water environment for the first time. In the absence of volatile organic solvents, MILATPs not only has the excellent properties of rapid extraction, but also exhibits a response to an external magnetic field which can be applied to assist phase separation. The phase behavior of MILATPs was investigated and phase equilibrium data were correlated by Merchuk equation. Various influencing factors on CAP recovery were systematically investigated and optimized. Under the optimal conditions, the preconcentration factor was 147.2 with the precision values (RSD%) of 2.42% and 4.45% for intra-day (n=6) and inter-day (n=6), respectively. The limit of detection (LOD) and limit of quantitation (LOQ) were 0.14ngmL(-1) and 0.42ngmL(-1), respectively. Fine linear range of 12.25ngmL(-1)-2200ngmL(-1) was obtained. Finally, the validated method was successfully applied for the analysis of CAP in some environmental waters with the recoveries for the spiked samples in the acceptable range of 94.6%-99.72%. Hopefully, MILATPs is showing great potential to promote new development in the field of extraction, separation and pretreatment of various biochemical samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Surface Confined Ionic Liquid-A New Stationary Phase for the Separation of Ephedrines in High-performance Liquid Chromatography

    Institute of Scientific and Technical Information of China (English)

    Shu Juan LIU; Feng ZHOU; Xiao Hua XIAO; Liang ZHAO; Xia LIU; Sheng Xiang JIANG

    2004-01-01

    In this article, a new and effective stationary phase based on ionic liquid modified silica is first reported and used for the separation of ephedrines in high-performance liquid chromatography (HPLC). The separation results indicate the high efficiency and reproducibility of the stationary phase. The electrostatic interaction, ion-exchange interaction between the solutes and the stationary phase are considered to attribute the effective separation. Moreover, the free silanols on the surface of the silica are effectively masked by the immobilized ionic liquid, a result of which is to decrease the non-specific absorption.

  5. For Noble Gases, Energy is Positive for the Gas Phase, Negative for the Liquid Phase

    CERN Document Server

    Asanuma, Nobu-Hiko

    2016-01-01

    We found from experimental data that for noble gases and H$_2$, the energy is positive for the gas phase, and negative for the liquid, possibly except the small vicinity of the critical point, about $(1- T/T_c) \\le 0.005$. The line $E=E_c$, in the supercritical region is found to lie close to the Widom line, where $E_c$ is the critical energy.

  6. Chirospecific analysis of plant volatiles

    Energy Technology Data Exchange (ETDEWEB)

    Tkachev, A V [N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation)

    2007-10-31

    Characteristic features of the analysis of plant volatiles by enantioselective gas (gas-liquid) chromatography and gas chromatography/mass spectrometry are discussed. The most recent advances in the design of enantioselective stationary phases are surveyed. Examples of the preparation of the most efficient phases based on modified cyclodextrins are given. Current knowledge on the successful analytical resolution of different types of plant volatiles (aliphatic and aromatic compounds and mono-, sesqui- and diterpene derivatives) into optical antipodes is systematically described. Chiral stationary phases used for these purposes, temperature conditions and enantiomer separation factors are summarised. Examples of the enantiomeric resolution of fragrance compounds and components of plant extracts, wines and essential oils are given.

  7. Chirospecific analysis of plant volatiles

    Science.gov (United States)

    Tkachev, A. V.

    2007-10-01

    Characteristic features of the analysis of plant volatiles by enantioselective gas (gas-liquid) chromatography and gas chromatography/mass spectrometry are discussed. The most recent advances in the design of enantioselective stationary phases are surveyed. Examples of the preparation of the most efficient phases based on modified cyclodextrins are given. Current knowledge on the successful analytical resolution of different types of plant volatiles (aliphatic and aromatic compounds and mono-, sesqui- and diterpene derivatives) into optical antipodes is systematically described. Chiral stationary phases used for these purposes, temperature conditions and enantiomer separation factors are summarised. Examples of the enantiomeric resolution of fragrance compounds and components of plant extracts, wines and essential oils are given.

  8. Determination of Medronic Acid and Its Related Substances by Reversed-Phase High-Performance Liquid Chromatography

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    An isocratic liquid chromatographic method with evaporative light scattering detection (ELSD) was developed for the determination of medronic acid and its related substance. Volatile pentylamine was used as ion-pairing agent. Separations were performend

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-10-24

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

  10. Two-phase and three-phase liquid-phase microextraction of hydrochlorothiazide and triamterene in urine samples.

    Science.gov (United States)

    Ahmad Panahi, Homayon; Ejlali, Maryam; Chabouk, Monireh

    2016-07-01

    This paper reports the applicability of two-phase and three-phase hollow fiber based liquid-phase microextraction (HF-LPME) for the extraction of hydrochlorothiazide (HYD) and triamterene (TRM) from human urine. The HYD in two-phase HF-LPME is extracted from 24 mL of the aqueous sample into an organic phase with microliter volume located inside the pores and lumen of a polypropylene hollow fiber as acceptor phase, but the TRM in three-phase HF-LPME is extracted from aqueous donor phase to organic phase and then back-extracted to the aqueous acceptor phase, which can be directly injected into HPLC for analysis. Under optimized conditions preconcentration factors of HYD and TRM were obtained as 128 and 239, respectively. The calibration curves were linear (R(2)  ≥ 0.995) in the concentration range of 1.0-100 µg/L for HYD and 2.0-100 µg/L for TRM. The limits of detection for HYD and TRM were 0.5 µg/L. The intra-day and inter-day RSD based on four replicates were obtained as ≤5.8 and ≤9.3%, respectively. The methods were successfully applied for determining the concentration of the drugs in urine samples. Copyright © 2015 John Wiley & Sons, Ltd.

  11. Toward the observation of a liquid-liquid phase transition in patchy origami tetrahedra: a numerical study.

    Science.gov (United States)

    Ciarella, Simone; Gang, Oleg; Sciortino, Francesco

    2016-12-01

    We evaluate the phase diagram of a model of tetrameric particles where the arms of the tetrahedra are made by six hard cylinders. An interacting site is present on each one of the four vertices allowing the particles to form a bonded network. These model particles provide a coarse-grained but realistic representation of recently synthesised DNA origami tetrahedra. We show that the resulting network is sufficiently empty to allow for partial interpenetration and it is sufficiently flexible to avoid crystallisation (at least on the numerical time scale), satisfying both criteria requested for the observation of a liquid-liquid critical point in tetrahedrally coordinated particles. Grand-canonical simulations provide evidence that, in silico, the model is indeed characterised, in addition to the gas-liquid transition, by a transition between two distinct liquid phases. Our results suggest that an experimental observation of a liquid-liquid transition in a colloidal system can be achieved in the near future.

  12. Relative hydrophobicity between the phases and partition of cytochrome-c in glycine ionic liquids aqueous two-phase systems.

    Science.gov (United States)

    Wu, Changzeng; Wang, Jianji; Li, Zhiyong; Jing, Jun; Wang, Huiyong

    2013-08-30

    In this work, glycine ionic liquids tetramethylammonium glycine ([N1111][Gly]), tetraethylammonium glycine ([N2222][Gly]), tetra-n-butylammonium glycine ([N4444][Gly]), tetra-n-butylphosphonium glycine ([P4444][Gly]) and tetra-n-pentylammonium glycine ([N5555][Gly]) were synthesized and used to prepare aqueous two-phase systems (ATPSs) in the presence of K2HPO4. Binodal curves of such ATPSs and partition coefficients of a series of dinitrophenylated (DNP) amino acids in these ATPSs were determined at 298.15K to understand the effect of cationic structure of the ionic liquids on the phase-forming ability of glycine ionic liquids, relative hydrophobicity between the phases in the ionic liquids ATPSs, and polarity of the ionic liquids-rich phases. With the attempt to correlate the relative hydrophobicity of the phases in the ATPSs with their extraction capability for proteins, partition coefficients of cytochrome-c in the ATPSs were also determined. It was shown that partition coefficients of cytochrome-c were in the range from 2.83 to 20.7 under the studied pH conditions. Then, hydrophobic interactions between cytochrome-c and the ionic liquid are suggested to be the main driving force for the preferential partition of cytochrome-c in the glycine ionic liquid-rich phases of the ATPSs. Result derived from polarity of the ionic liquids-rich phases supports this mechanism.

  13. Application of dispersive liquid-liquid microextraction and gas chromatography with mass spectrometry for the determination of oxygenated volatile organic compounds in effluents from the production of petroleum bitumen.

    Science.gov (United States)

    Boczkaj, Grzegorz; Makoś, Patrycja; Przyjazny, Andrzej

    2016-07-01

    We present a new procedure for the determination of oxygenated volatile organic compounds in samples of postoxidative effluents from the production of petroleum bitumens using dispersive liquid-liquid microextraction and gas chromatography with mass spectrometry. The eight extraction parameters were optimized for 43 oxygenated volatile organic compounds. The detection limits obtained ranged from 0.07 to 0.82 μg/mL for most of the analytes, the precision was good (relative standard deviation below 2.91% at the 5 μg/mL level and 4.75% at the limit of quantification), the recoveries for the majority of compounds varied from 70.6 to 118.9%, and the linear range was wide, which demonstrates the usefulness of the procedure. The developed procedure was used for the determination of oxygenated volatile organic compounds in samples of raw postoxidative effluents and in effluents after chemical treatment. In total, 23 compounds at concentration levels from 0.37 to 32.95 μg/mL were identified in real samples. The same samples were also analyzed in the SCAN mode, which resulted in four more phenol derivatives being identified and tentatively determined. The studies demonstrated the need for monitoring volatile organic compounds content in effluents following various treatments due to the formation of secondary oxygenated volatile organic compounds.

  14. Exposure to volatile organic compounds and kidney dysfunction in thin film transistor liquid crystal display (TFT-LCD) workers.

    Science.gov (United States)

    Chang, Ta-Yuan; Huang, Kuei-Hung; Liu, Chiu-Shong; Shie, Ruei-Hao; Chao, Keh-Ping; Hsu, Wen-Hsin; Bao, Bo-Ying

    2010-06-15

    Many volatile organic compounds (VOCs) are emitted during the manufacturing of thin film transistor liquid crystal displays (TFT-LCDs), exposure to some of which has been reported to be associated with kidney dysfunction, but whether such an effect exists in TFT-LCD industry workers is unknown. This cross-sectional study aimed to investigate the association between exposure to VOCs and kidney dysfunction among TFT-LCD workers. The results showed that ethanol (1811.0+/-1740.4 ppb), acetone (669.0+/-561.0 ppb), isopropyl alcohol (187.0+/-205.3 ppb) and propylene glycol monomethyl ether acetate (PGMEA) (102.9+/-102.0 ppb) were the four dominant VOCs present in the workplace. The 63 array workers studied had a risk of kidney dysfunction 3.21-fold and 3.84-fold that of 61 cell workers and 18 module workers, respectively. Workers cumulatively exposed to a total level of isopropyl alcohol, PGMEA and propylene glycol monomethyl ether> or =324 ppb-year had a significantly higher risk of kidney dysfunction (adjusted OR=3.41, 95% CI=1.14-10.17) compared with those exposed to LCD industry, and cumulative exposure to specific VOCs might be associated with kidney dysfunction.

  15. Effect of Mono-and Di-ethanolammonium Formate Ionic Liquids on the Volatility of Water, Ethanol, and Methanol

    Institute of Scientific and Technical Information of China (English)

    李雪梅; 沈冲; 李春喜

    2013-01-01

    Vapor pressures were measured for six binary systems containing water, ethanol, or methanol with one of the two ionic liquids (ILs) at different component concentrations and temperatures using a quasi-static ebulliometer, with the ILs mono-ethanolammonium formate ([HMEA][HCOO]) and di-ethanolammonium formate ([HDEA][HCOO]). The vapor pressures of the IL-containing binary systems are well correlated using the NRTL model with an overall average absolute relative deviation (AARD) of 0.0062. The effect of ILs on the vapor pressure depression of sol-vents at 0.050 mole fraction of IL is that [HDEA][HCOO]>[HMEA][HCOO], and the vapor pressure lowering de-gree follows the order of water>methanol>ethanol. Further, the activity coefficients of three solvents (viz. water, ethanol, and methanol) for the binary systems{solvent (1)+IL (2)}predicted based on the fitted NRTL parameters at T=333.15 K indicate that the two ILs generate a negative deviation from Raoult’s law for water and methanol and a positive deviation for ethanol to a varying degree, change the relative volatility of a solvent. [HMEA][HCOO] may be a promising entrainer to efficiently separate ethanol aqueous solutions by special rectification.

  16. Liquid disordered-liquid ordered phase coexistence in bicelles containing unsaturated lipids and cholesterol.

    Science.gov (United States)

    Schmidt, Miranda L; Davis, James H

    2016-04-01

    Magnetically orienting bicelles are often made by combining the long chain phospholipid 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) with the short chain phospholipid 1,2-dicaproyl-sn-glycero-3-phosphocholine (DCPC) in buffer. These bicelles orient with their bilayer normals perpendicular to the external magnetic field. We have examined the phase behaviour of DMPC/DCPC bicelles and the effects of cholesterol and the unsaturated phospholipid 1,2-dipalmitoleoyl-sn-glycero-3-phosphocholine (DPoPC) as a function of temperature using static solid state (2)H nuclear magnetic resonance spectroscopy. As expected, cholesterol has an ordering effect on the long phospholipid chains and this is reflected in the phase behaviour of the bicelle mixtures. Liquid disordered-liquid ordered, fluid-fluid phase coexistence is observed in DMPC/cholesterol/DCPC bicelles with cholesterol mole fractions of 0.13 and higher. DPoPC/DMPC/cholesterol/DCPC bicelles also exhibit two fluid phase coexistence over a broad range of temperatures and compositions. Bicelles can provide a useful medium in which to study membrane bound peptides and proteins. The orientation parallel to the magnetic field is favourable for studying membrane peptides/proteins because information about the orientation of relevant molecular bonds or internuclear vectors can be obtained directly from the resulting (2)H spectra. Lanthanide ions can be used to flip the bicelles to have their bilayer normals parallel to the external magnetic field. Yb(3+) was used to flip the DPoPC/DMPC/cholesterol/DCPC bicelles while Eu(3+) was found to be ineffective at flipping bicelles containing cholesterol in the present work.

  17. Ionic liquids in solid-phase microextraction: a review.

    Science.gov (United States)

    Ho, Tien D; Canestraro, Anthony J; Anderson, Jared L

    2011-06-10

    Solid-phase microextraction (SPME) has undergone a surge in popularity within the field of analytical chemistry in the past two decades since its introduction. Owing to its nature of extraction, SPME has become widely known as a quick and cost-effective sample preparation technique. Although SPME has demonstrated extraordinary versatility in sampling capabilities, the technique continues to experience a tremendous growth in innovation. Presently, increasing efforts have been directed towards the engineering of novel sorbent material in order to expand the applicability of SPME for a wider range of analytes and matrices. This review highlights the application of ionic liquids (ILs) and polymeric ionic liquids (PILs) as innovative sorbent materials for SPME. Characterized by their unique physico-chemical properties, these compounds can be structurally-designed to selectively extract target analytes based on unique molecular interactions. To examine the advantages of IL and PIL-based sorbent coatings in SPME, the field is reviewed by gathering available experimental data and exploring the sensitivity, linear calibration range, as well as detection limits for a variety of target analytes in the methods that have been developed.

  18. Non-Fermi liquid phase in metallic Skyrmion crystals

    Science.gov (United States)

    Watanabe, Haruki; Parameswaran, Siddharth; Raghu, Srinivas; Vishwanath, Ashvin

    2014-03-01

    Motivated by reports of a non-Fermi liquid state in MnSi, we examine the effect of coupling phonons of an incommensurate skyrmion crystal (SkX) to conduction electrons. We find that non-Fermi liquid behavior emerges in both two and three dimensions over the entire phase, due to an anomalous electron-phonon coupling that is linked to the net skyrmion density. A small parameter, the spiral wave vector in lattice units, allows us to exercise analytic control and ignore Landau damping of phonons over a wide energy range. At the lowest energy scales the problem is similar to electrons coupled to a gauge field. The best prospects for realizing these effects is in short period skyrmion lattice systems such as MnGe or epitaxial MnSi films. We also compare our results with the unusual T 3 / 2 scaling of temperature dependent resistivity seen in high pressure experiments on MnSi. We acknowledge support from the NSF via Grant DMR-0645691, the DOE Office of Basic Energy Sciences via contract DE-AC02-76SF00515, and the Simons, Templeton, and Alfred P. Sloan Foundations.

  19. Semiphenomenological model for gas-liquid phase transitions.

    Science.gov (United States)

    Benilov, E S; Benilov, M S

    2016-03-01

    We examine a rarefied gas with inter-molecular attraction. It is argued that the attraction force amplifies random density fluctuations by pulling molecules from lower-density regions into high-density regions and thus may give rise to an instability. To describe this effect, we use a kinetic equation where the attraction force is taken into account in a way similar to how electromagnetic forces in plasma are treated in the Vlasov model. It is demonstrated that the instability occurs when the temperature T is lower than a certain threshold value T(s) depending on the gas density. It is further shown that, even if T is only marginally lower than T(s), the instability generates clusters with density much higher than that of the gas. These results suggest that the instability should be interpreted as a gas-liquid phase transition, with T(s) being the temperature of saturated vapor and the high-density clusters representing liquid droplets.

  20. Acoustic levitation of liquid drops: Dynamics, manipulation and phase transitions.

    Science.gov (United States)

    Zang, Duyang; Yu, Yinkai; Chen, Zhen; Li, Xiaoguang; Wu, Hongjing; Geng, Xingguo

    2017-05-01

    The technique of acoustic levitation normally produces a standing wave and the potential well of the sound field can be used to trap small objects. Since no solid surface is involved it has been widely applied for the study of fluid physics, nucleation, bio/chemical processes, and various forms of soft matter. In this article, we survey the works on drop dynamics in acoustic levitation, focus on how the dynamic behavior is related to the rheological properties and discuss the possibility to develop a novel rheometer based on this technique. We review the methods and applications of acoustic levitation for the manipulation of both liquid and solid samples and emphasize the important progress made in the study of phase transitions and bio-chemical analysis. We also highlight the possible open areas for future research. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Mass transfer mechanism in chiral reversed phase liquid chromatography.

    Science.gov (United States)

    Gritti, Fabrice; Guiochon, Georges

    2014-03-01

    The mechanism of mass transfer in chiral chromatography was investigated using an experimental protocol already applied in RPLC and HILIC chromatography. The different contributions to the reduced height equivalent to a theoretical plate (HETP) include the longitudinal diffusion HETP term, the solid-liquid mass transfer resistance HETP term, the short-range eddy dispersion HETP term, and the long-range eddy dispersion HETP term. Their accurate measurement permits the determination of the adsorption rate constant kads of trans-stilbene enantiomers on a column packed with Lux 5 μm Cellulose-1 particles. The experimental results demonstrate that the number of adsorption-desorption steps per unit time of chiral compounds on polysaccharide-based chiral stationary phases is four orders of magnitude smaller than that of achiral compounds.

  2. Liquid phase ozonation of cyclohexanol using acetic acid as solvent

    Energy Technology Data Exchange (ETDEWEB)

    Encinar, J.M.; Beltran, F.J. (Departamento de Ingeneria Quimica y Energetica. Facultad de Ciencias. Badajoz (Spain)); Frades, J.M. (Departamento de Ingenieria Quimica. E.U.P. Almaden (Spain))

    1994-01-01

    The liquid phase oxidation of cyclohexanol in an acetic acid medium using a mixture of oxygen and ozone has been studied in a laboratory semi batch reactor. The influence of temperature, ozone partial pressure, initial concentration of cyclohexanol on its conversion and yield and distribution of products has been observed. Under the experimental conditions investigated formation of peroxydic compounds and mono basic acids was not relevant; the major products obtained were cyclohexanone and adipic and glutaric acids although analytical chromatograms revealed the presence of other products unidentified. Formation of these products is qualitatively explained by means of a chain-radical mechanism. Finally, it is proposed an empirical kinetic equation which relates the variables mentioned above with the reaction rates. This equation reproduces the experimental results with deviations less than 10%. (Author) 21 refs.

  3. Preparation of ITO Nanoparticles by Liquid Phase Coprecipitation Method

    Directory of Open Access Journals (Sweden)

    Zhanlai Ding

    2010-01-01

    Full Text Available The nanoscale indium tin oxide (ITO particles are synthesied by liquid phase coprecipitation method under given conditions with solution of indium chloride, tin chloride, and ammonia. The absolute ethyl alcohol or deionized water was used as solvent and the dodecylamine or hexadecylamine surfactant was used as a dispersant in the reaction system. The sample powder was characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM, and high-resolution electron microscopy (HRTEM. Based on the transmission electron micrograph, the influences of the two different solvents and the two different dispersants on the nanoparticle size and dispersion were studied, respectively. The results showed that the ITO particles are finely crystallized body-centered cubic structure. The particle size has distributed in 30 nm to 90 nm.

  4. Volatilization and Thermal Decomposition Mechanisms of Room-Temperature Ionic Liquids (PRE-PRINT)

    Science.gov (United States)

    2017-03-07

    reactions and possible polymerization to higher mass species. Note the increase in fragmentation in the spectra as a result of increased internal energy...imidazolium RTILs indicates possible anion-cation reactions and possible polymerization to higher mass species (Figures 1b and 2b). Note the...studies of RTILs at the Advanced Light source will greatly aid in the understanding of the nature of RTILs in the gas phase, as well as begin to

  5. Application of mesoporous carbon as a solid-phase microextraction fiber coating for the extraction of volatile aromatic compounds.

    Science.gov (United States)

    Zhang, Xi; Zang, Xiaohuan; Zhang, Guijiang; Wang, Chun; Wang, Zhi

    2015-08-01

    A mesoporous carbon was fabricated using MCM-41 as a template and sucrose as a carbon source. The carbon material was coated on stainless-steel wires by using the sol-gel technique. The prepared solid-phase microextraction fiber was used for the extraction of five volatile aromatic compounds (chlorobenzene, ethylbenzene, o-xylene, bromobenzene, and 4-chlorotoluene) from tea beverage samples (red tea and green tea) prior to gas chromatography with mass spectrometric detection. The main experimental parameters affecting the extraction of the volatile aromatic compounds by the fiber, including the extraction time, sample volume, extraction temperature, salt addition, and desorption conditions, were investigated. The linearity was observed in the range from 0.1 to 10.0 μg/L with the correlation coefficients (r) ranging from 0.9923 to 0.9982 and the limits of detection were less than 10.0 ng/L. The recoveries of the volatile aromatic compounds by the method from tea beverage samples at spiking levels of 1.0 and 10.0 μg/L ranged from 73.1 to 99.1%.

  6. Profile of volatile compounds in 11 brandies by headspace solid-phase microextraction followed by gas chromatography-mass spectrometry.

    Science.gov (United States)

    Zhao, Y; Xu, Y; Li, J; Fan, W; Jiang, W

    2009-03-01

    A headspace solid-phase microextraction (HS-SPME) method coupled with gas chromatography-mass spectrometry (GC-MS) was applied for the qualitative or semiquantitative characterization of brandy volatiles. SPME variables (SPME fiber, extraction temperature and time, and ethanol concentration) were optimized. A total of 144 compounds were from the brandies' volatiles, tentatively identified or identified by comparing mass spectra and retention indices of the standards or from literature. Of these, 57 are common to 11 brandies. They were mainly represented by esters and alcohols, such as 2-methyl propanol, 3-methyl butanol, 1-hexanol, ethyl octanoate, and ethyl decanoate, which were quantitatively determined. Chromatographic peaks were integrated using selective ion method (SIM) and the semiquantitative data analyzed using principal component analysis (PCA) and cluster analysis (CA) to study relationships between volatile composition and brandy. Eleven brandies were differentiated into 3 groups: 1 for Hennessy VSOP and XO samples, 1 for Changyu PEGASE VSOP and XO-1, 2, 3 samples, and the other for Changyu PEGASE brandy and VO, Taro brandy, Baiyang River brandy, and Wealth XO samples. The classification of groups is consistent with the brandy samples by variety and grade.

  7. Volatile composition of Catharanthus roseus (L.) G. Don using solid-phase microextraction and gas chromatography/mass spectrometry.

    Science.gov (United States)

    De Pinho, P Guedes; Gonçalves, Rui F; Valentão, Patrícia; Pereira, David M; Seabra, Rosa M; Andrade, Paula B; Sottomayor, Mariana

    2009-04-05

    A total of 88 volatile and semi-volatile components were formally or tentatively identified in flowers, leaves and stems of Catharanthus roseus (L.) G. Don (cv. Little Bright Eye), by headspace solid-phase microextraction (HS-SPME) and by dichloromethane extraction, combined with gas chromatography-mass spectrometry (GC-MS). These include some diterpenic compounds (manool and manoyl oxides), a sesquiterpen (alpha-bisabolol), and some pyridine, pyrazine, indol and carotenoid derivatives. Applying multivariate analysis (principal component analysis and agglomerative hierarchic cluster analysis) to the HS-SPME-GC-MS data, it was possible to characterize each part of the vegetal material using a relative small number of compounds. Hence, flowers were richer in terpenic molecules (including limonene), alpha-bisabolol, methyljasmonate, cis-jasmone, 2-phenylethanol, phenylacetaldehyde, trans-2-octenal, benzylic alcohol and 2-isobutyl-3-methoxypyrazine. Leaves can be characterized by the methyl and propyl esters of fatty acids, mono- and disaturated, trans-phytol, carotenoid derivative compounds, hydrofarnesylacetone, methylanthranilate, manool and epi-manool oxide, while stems have high levels of volatile aldehydes, such as hexanal, octanal, cis-2-nonenal, cis-2-decenal, cis, trans-2,6-nonadienal, trans, trans-2,4-decadienal and cis, trans-2,4-decadienal. Dichloromethane extraction allowed also the identification of some alkaloid-like compounds that were not detected by HS-SPME.

  8. Volatile flavour constituent patterns of Terras Madeirenses red wines extracted by dynamic headspace solid-phase microextraction.

    Science.gov (United States)

    Perestrelo, Rosa; Caldeira, Michael; Rodrigues, Freddy; Câmara, José S

    2008-06-01

    A suitable analytical procedure based on static headspace solid-phase microextraction (SPME) followed by thermal desorption gas chromatography-ion trap mass spectrometry detection (GC-(ITD)MS), was developed and applied for the qualitative and semi-quantitative analysis of volatile components of Portuguese Terras Madeirenses red wines. The headspace SPME method was optimised in terms of fibre coating, extraction time, and extraction temperature. The performance of three commercially available SPME fibres, viz. 100 mum polydimethylsiloxane; 85 mum polyacrylate, PA; and 50/30 mum divinylbenzene/carboxen on polydimethylsiloxane, was evaluated and compared. The highest amounts extracted, in terms of the maximum signal recorded for the total volatile composition, were obtained with a PA coating fibre at 30 degrees C during an extraction time of 60 min with a constant stirring at 750 rpm, after saturation of the sample with NaCl (30%, w/v). More than sixty volatile compounds, belonging to different biosynthetic pathways, have been identified, including fatty acid ethyl esters, higher alcohols, fatty acids, higher alcohol acetates, isoamyl esters, carbonyl compounds, and monoterpenols/C(13)-norisoprenoids.

  9. Liquid-liquid and liquid-solid phase separation in protein-polyelectrolyte systems.

    Science.gov (United States)

    Comert, Fatih; Dubin, Paul L

    2017-01-01

    The coacervation of systems containing colloids (e.g. proteins or micelles) and polyelectrolytes (notably ionic polysaccharides) is often accompanied by precipitation. This can introduce inhomogeneity, irreversibility and irreproducible kinetics in applications in food science and bioengineering, with negative impact on texture and stability of food products, and unpredictable delivery of active "payloads." The relationship between coacervation and precipitation is obscure in that coacervates might be intermediates in the formation of precipitates, or else the two phenomena might proceed by different but possibly simultaneous mechanisms. This review will summarize the recent literature on coacervation/precipitation in protein-polyelectrolyte systems for which reports are most abundant, particularly in the context of food science. We present current findings and opinions about the relationship between the two types of phase separation. Results vary considerably depending not only on the protein-polyelectrolyte pairs chosen, but also on conditions including macromolecular concentrations and ionic strength. Nevertheless, we offer some general approaches that could explain a variety of observations. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Dynamic single-interface hollow fiber liquid phase microextraction of Cr(VI) using ionic liquid containing supported liquid membrane.

    Science.gov (United States)

    Pimparu, Rungaroon; Nitiyanontakit, Sira; Miró, Manuel; Varanusupakul, Pakorn

    2016-12-01

    The concept of dynamic single-interface hollow fiber membrane liquid-phase microextraction (HF-LPME), where the target analyte was extracted on-line and eluted inside the lumen of the HF membrane, was explored. An ionic liquid containing supported liquid membrane was used for the trace determination of Cr(VI) as a model compound. Since the extraction took place on-line inside the hollow fiber membrane, the mass transfer behavior was described and discussed in comparison with the conventional HF-LPME. The extraction efficiency was improved by a recirculation configuration of the sample solution at relatively high sampling flow rates as a result of the increased effective contact area. The positive pressure observed to be built up during extraction was overcome by a flow-balancing pressure design. The dynamic single-interface HF-LPME method with an enrichment factor of 41, a detection limit of 1.2µgL(-1) and determination limit of 4.0µgL(-1) was successfully applied to the reliable determination of Cr(VI) from environmental water samples. The quantification limit is below the maximum contaminant level in drinking water, set at 10µgL(-1) of hexavalent chromium by the California Environmental Protection Agency.

  11. Quantification approach for assessment of sparkling wine volatiles from different soils, ripening stages, and varieties by stir bar sorptive extraction with liquid desorption.

    Science.gov (United States)

    Coelho, Elisabete; Coimbra, Manuel A; Nogueira, J M F; Rocha, Sílvia M

    2009-03-01

    Stir bar sorptive extraction with liquid desorption followed by large volume injection coupled to gas chromatography-quadrupole mass spectrometry (SBSE-LD/LVI-GC-qMS) was applied for the quantification of varietal and fermentative volatiles in sparkling wines. The analytical data were performed by using suitable standards of monoterpene hydrocarbons (alpha-pinene), monoterpenols (linalool), sesquiterpenoids (E,E-farnesol, Z-nerolidol, and guaiazulene), C(13) norisoprenoids (beta-ionone), aliphatic and aromatic alcohols (hexanol and 2-phenylethanol), and esters (hexyl acetate and ethyl decanoate) as model compounds. The wine volatiles were quantified using the structurally related standards. The methodology showed good linearity over the concentration range tested, with correlation coefficients ranging from 0.950 to 0.997, and a reproducibility of 9-18%. The SBSE-LD/LVI-GC-qMS methodology allowed, in a single run, the quantification of 71 wine volatiles that can be quantified accurately at levels lower than their respective olfactory thresholds. This methodology was used for assessment of sparkling wine volatiles from different soils, ripening stages, and varieties. The variety and soil influenced significantly the volatile composition of sparkling wines; lower effect was observed for the ripening stage of grapes picked up one week before or after the maturity state.

  12. 2-Aminoacetophenone Is the Main Volatile Phase I Skatole Metabolite in Pietrain × Baden-Württemberg Hybrid Type Boars.

    Science.gov (United States)

    Gerlach, Christoph; Elsinghorst, Paul W; Schmarr, Hans-Georg; Wüst, Matthias

    2016-02-10

    Skatole metabolites have been considered as putative contributors to boar taint. Recently, 2-aminoacetophenone, a volatile phase I skatole metabolite, was identified in back fat samples from boars of Pietrain × Baden-Württemberg hybrid type. This paper addresses the question of the physiological origin of the observed 2-aminoacetophenone in these pigs. Microsomal fractions from nine boars were isolated, and formation of skatole metabolites was subsequently analyzed by stable-isotope dilution analysis (SIDA) using headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME/GC-MS). Significant breed-related differences in phase I skatole metabolism were observed, explaining the high levels of 2-aminoacetophenone in Pietrain × Baden-Württemberg hybrid type boars.

  13. Retention mechanism for polycyclic aromatic hydrocarbons in reversed-phase liquid chromatography with monomeric stationary phases.

    Science.gov (United States)

    Rafferty, Jake L; Siepmann, J Ilja; Schure, Mark R

    2011-12-23

    Reversed-phase liquid chromatography (RPLC) is the foremost technique for the separation of analytes that have very similar chemical functionalities, but differ only in their molecular shape. This ability is crucial in the analysis of various mixtures with environmental and biological importance including polycyclic aromatic hydrocarbons (PAHs) and steroids. A large amount of effort has been devoted to studying this phenomenon experimentally, but a detailed molecular-level description remains lacking. To provide some insight on the mechanism of shape selectivity in RPLC, particle-based simulations were carried out for stationary phases and chromatographic parameters that closely mimic those in an experimental study by Sentell and Dorsey [J. Chromatogr. 461 (1989) 193]. The retention of aromatic hydrocarbons ranging in size from benzene to the isomeric PAHs of the formula C(18)H(12) was examined for model RPLC systems consisting of monomeric dimethyl octadecylsilane (ODS) stationary phases with surface coverages ranging from 1.6 to 4.2 μmol/m(2) (i.e., stationary phases yielding low to intermediate shape selectivity) in contact with a 67/33 mol% acetonitrile/water mobile phase. The simulations show that the stationary phase acts as a very heterogeneous environment where analytes with different shapes prefer different spatial regions with specific local bonding environments of the ODS chains. However, these favorable retentive regions cannot be described as pre-existing cavities because the chain conformation in these local stationary phase regions adapts to accommodate the analytes.

  14. Low Density Phases in a Uniformly Charged Liquid

    Science.gov (United States)

    Knüpfer, Hans; Muratov, Cyrill B.; Novaga, Matteo

    2016-07-01

    This paper is concerned with the macroscopic behavior of global energy minimizers in the three-dimensional sharp interface unscreened Ohta-Kawasaki model of diblock copolymer melts. This model is also referred to as the nuclear liquid drop model in the studies of the structure of highly compressed nuclear matter found in the crust of neutron stars, and, more broadly, is a paradigm for energy-driven pattern forming systems in which spatial order arises as a result of the competition of short-range attractive and long-range repulsive forces. Here we investigate the large volume behavior of minimizers in the low volume fraction regime, in which one expects the formation of a periodic lattice of small droplets of the minority phase in a sea of the majority phase. Under periodic boundary conditions, we prove that the considered energy {Γ}-converges to an energy functional of the limit "homogenized" measure associated with the minority phase consisting of a local linear term and a non-local quadratic term mediated by the Coulomb kernel. As a consequence, asymptotically the mass of the minority phase in a minimizer spreads uniformly across the domain. Similarly, the energy spreads uniformly across the domain as well, with the limit energy density minimizing the energy of a single droplet per unit volume. Finally, we prove that in the macroscopic limit the connected components of the minimizers have volumes and diameters that are bounded above and below by universal constants, and that most of them converge to the minimizers of the energy divided by volume for the whole space problem.

  15. Extensive database of liquid phase diffusion coefficients of some frequently used test molecules in reversed-phase liquid chromatography and hydrophilic interaction liquid chromatography.

    Science.gov (United States)

    Song, Huiying; Vanderheyden, Yoachim; Adams, Erwin; Desmet, Gert; Cabooter, Deirdre

    2016-07-15

    Diffusion plays an important role in all aspects of band broadening in chromatography. An accurate knowledge of molecular diffusion coefficients in different mobile phases is therefore crucial in fundamental column performance studies. Correlations available in literature, such as the Wilke-Chang equation, can provide good approximations of molecular diffusion under reversed-phase conditions. However, these correlations have been demonstrated to be less accurate for mobile phases containing a large percentage of acetonitrile, as is the case in hydrophilic interaction liquid chromatography. A database of experimentally measured molecular diffusion coefficients of some 45 polar and apolar compounds that are frequently used as test molecules under hydrophilic interaction liquid chromatography and reversed-phase conditions is therefore presented. Special attention is given to diffusion coefficients of polar compounds obtained in large percentages of acetonitrile (>90%). The effect of the buffer concentration (5-10mM ammonium acetate) on the obtained diffusion coefficients is investigated and is demonstrated to mainly influence the molecular diffusion of charged molecules. Diffusion coefficients are measured using the Taylor-Aris method and hence deduced from the peak broadening of a solute when flowing through a long open tube. The validity of the set-up employed for the measurement of the diffusion coefficients is demonstrated by ruling out the occurrence of longitudinal diffusion, secondary flow interactions and extra-column effects, while it is also shown that radial equilibration in the 15m long capillary is effective.

  16. From quantum mechanics to finance: Microfoundations for jumps, spikes and high volatility phases in diffusion price processes

    Science.gov (United States)

    Henkel, Christof

    2017-03-01

    We present an agent behavior based microscopic model that induces jumps, spikes and high volatility phases in the price process of a traded asset. We transfer dynamics of thermally activated jumps of an unexcited/excited two state system discussed in the context of quantum mechanics to agent socio-economic behavior and provide microfoundations. After we link the endogenous agent behavior to price dynamics we establish the circumstances under which the dynamics converge to an Itô-diffusion price processes in the large market limit.

  17. The Influence of Disorder on Thermotropic Nematic Liquid Crystals Phase Behavior

    Directory of Open Access Journals (Sweden)

    Samo Kralj

    2009-09-01

    Full Text Available We review the theoretical research on the influence of disorder on structure and phase behavior of condensed matter system exhibiting continuous symmetry breaking focusing on liquid crystal phase transitions. We discuss the main properties of liquid crystals as adequate systems in which several open questions with respect to the impact of disorder on universal phase and structural behavior could be explored. Main advantages of liquid crystalline materials and different experimental realizations of random field-type disorder imposed on liquid crystal phases are described.

  18. Head Space Solid Phase Micro-Extraction (HS - SPME of volatile organic compounds produced by Sporidiobolus salmonicolor (CBS 2636

    Directory of Open Access Journals (Sweden)

    Eunice Valduga

    2010-12-01

    Full Text Available The aim of the present study was the assessment of volatile organic compounds produced by Sporidiobolus salmonicolor (CBS 2636 using methyl and ethyl ricinoleate, ricinoleic acid and castor oil as precursors. The analysis of the volatile organic compounds was carried out using Head Space Solid Phase Micro-Extraction (HS - SPME. Factorial experimental design was used for investigating extraction conditions, verifying stirring rate (0-400 rpm, temperature (25-60 ºC, extraction time (10-30 minutes, and sample volume (2-3 mL. The identification of volatile organic compounds was carried out by Gas Chromatography with Mass Spectrum Detector (GC/MSD. The conditions that resulted in maximum extraction were: 60 ºC, 10 minutes extraction, no stirring, sample volume of 2.0 mL, and addition of saturated KCl (1:10 v/v. In the bio-production of volatile organic compounds the effect of stirring rate (120-200 rpm, temperature (23-33 ºC, pH (4.0-8.0, precursor concentration (0.02-0.1%, mannitol (0-6%, and asparagine concentration (0-0.2% was investigated. The bio-production at 28 ºC, 160 rpm, pH 6,0 and with the addition of 0.02% ricinoleic acid to the medium yielded the highest production of VOCs, identified as 1,4-butanediol, 1,2,2-trimethylciclopropilamine, beta-ionone; 2,3-butanodione, pentanal, tetradecane, 2-isononenal, 4-octen-3-one, propanoic acid, and octadecane.

  19. Characterization of volatile compounds of Daucus crinitus Desf. Headspace Solid Phase Microextraction as alternative technique to Hydrodistillation

    Directory of Open Access Journals (Sweden)

    Tabti Boufeldja

    2010-09-01

    Full Text Available Abstract Background Traditionally, the essential oil of aromatic herbs is obtained using hydrodistillation (HD. Because the emitted volatile fraction plays a fundamental role in a plant's life, various novel techniques have been developed for its extraction from plants. Among these, headspace solid phase microextraction (HS-SPME can be used to obtain a rapid fingerprint of a plant's headspace. Daucus crinitus Desf. is a wild plant that grows along the west coast of Algeria. Only a single study has dealt with the chemical composition of the aerial part oils of Algerian D. crinitus, in which isochavicol isobutyrate (39.0%, octyl acetate (12.3%, and β-caryophyllene (5.4% were identified. Using GC-RI and GC-MS analysis, the essential oils and the volatiles extracted from separated organs of D. crinitus Desf. were studied using HS-SPME. Results GC-RI and GC-MS analysis identified 72 and 79 components in oils extracted using HD and in the volatile fractions extracted using SPME, respectively. Two types of essential oils were produced by the plant: the root oils had aliphatic compounds as the main component (87.0%-90.1%, and the aerial part oils had phenylpropanoids as the main component (43.1%-88.6%. HS-SPME analysis showed a more precise distribution of compounds in the organs studied: oxygenated aliphatic compounds were well represented in the roots (44.3%-84.0%, hydrocarbon aliphatic compounds were in the leaves and stems (22.2%-87.9%, and phenylpropanoids were in the flowers and umbels (47.9%-64.2%. Moreover, HS-SPME allowed the occurrence of isochavicol (29.6 - 34.7% as main component in D. crinitus leaves, but it was not detected in the oils, probably because of its solubility in water. Conclusions This study demonstrates that HD and HS-SPME modes could be complimentary extraction techniques in order to obtain the complete characterization of plant volatiles.

  20. Mechanism of Phase Transition from Liquid to Gas Under Dielectric Barrier Discharge Plasma

    Science.gov (United States)

    Wang, Qiuying; Li, Sen; Gu, Fan

    2010-10-01

    Liquid gasification phenomenon was observable in liquid-solid dielectric barrier discharge (DBD) experiments. Starting from classical thermodynamics, this study aimed at finding the reason of liquid gasification in the DBD experiments. Fluid statics and electrohydrodynamics were adopted to analyze the mechanism of phase transition from liquid to gas. The Sumoto effect was also employed to visually explain the change in the pressure of fluid due to the electric field. It was concluded from both theoretical analysis and experiment that the change in liquid pressure was a key factor causing liquid to gasify in DBD conditions. Furthermore, it was stressed that the liquid pressure was affected by many parameters including liquid permittivity, voltage, electric intensity, size of the discharge space and uniformity of the electric field distribution, etc. All of them affected DBD liquid gasification. The related results would provide useful theoretical evidence for multi-phase DBD applications.

  1. Determination of volatile organic compounds including alcohols in refill fluids and cartridges of electronic cigarettes by headspace solid-phase micro extraction and gas chromatography-mass spectrometry.

    Science.gov (United States)

    Lim, Hyun-Hee; Shin, Ho-Sang

    2017-02-01

    An analytical method for the detection of 14 volatile organic compounds (VOCs) was developed to investigate VOCs in refill fluids and cartridges of electronic cigarettes (EC) using headspace solid-phase micro extraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). In total, 14 VOCs were identified and quantified in 283 flavored liquids, 21 nicotine liquids, and 12 disposable cartridges. The detected concentration ranges of the VOCs are as follows: benzene (0.008-2.28 mg L(-1)), toluene (0.006-0.687 mg L(-1)), ethylbenzene (0.01-1.21 mg L(-1)), m-xylene (0.002-1.13 mg L(-1)), p-xylene (0.007-2.8 mg L(-1)), o-xylene (0.004-2.27 mg L(-1)), styrene (0.011-0.339 mg L(-1)), ethyl acetate (0.3-669.9 mg L(-1)), ethanol (16-38,742 mg L(-1)), methanol (66-3375 mg L(-1)), pyridine (0.077-99.7 mg L(-1)), acetylpyrazine (0.077-147 mg L(-1)), 2,3,5-trimethylpyrazine (0.008-96.8 mg L(-1)), and octamethylcyclotetrasiloxane (0.1-57.2 mg L(-1)). Benzene, toluene, ethylbenzene, m-xylene, p-xylene, and o-xylene coexisted in samples, which may have originated from the use of petrogenic hydrocarbons as an extraction solvent for flavor and nicotine from natural plants. The maximum detected concentrations of benzene, methanol, and ethanol in liquid samples were found in quantities higher than their authorized maximum limits as residual solvents in pharmaceutical products.

  2. Purification of flavonoids from licorice using an off-line preparative two-dimensional normal-phase liquid chromatography/reversed-phase liquid chromatography method.

    Science.gov (United States)

    Fan, Yunpeng; Fu, Yanhui; Fu, Qing; Cai, Jianfeng; Xin, Huaxia; Dai, Mei; Jin, Yu

    2016-07-01

    An orthogonal (71.9%) off-line preparative two-dimensional normal-phase liquid chromatography/reversed-phase liquid chromatography method coupled with effective sample pretreatment was developed for separation and purification of flavonoids from licorice. Most of the nonflavonoids were firstly removed using a self-made Click TE-Cys (60 μm) solid-phase extraction. In the first dimension, an industrial grade preparative chromatography was employed to purify the crude flavonoids. Click TE-Cys (10 μm) was selected as the stationary phase that provided an excellent separation with high reproducibility. Ethyl acetate/ethanol was selected as the mobile phase owing to their excellent solubility for flavonoids. Flavonoids co-eluted in the first dimension were selected for further purification using reversed-phase liquid chromatography. Multiple compounds could be isolated from one normal-phase fraction and some compounds with bad resolution in one-dimensional liquid chromatography could be prepared in this two-dimensional system owing to the orthogonal separation. Moreover, this two-dimensional liquid chromatography method was beneficial for the preparation of relatively trace flavonoid compounds, which were enriched in the first dimension and further purified in the second dimension. Totally, 24 flavonoid compounds with high purity were obtained. The results demonstrated that the off-line two-dimensional liquid chromatography method was effective for the preparative separation and purification of flavonoids from licorice.

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

    Science.gov (United States)

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

    2015-02-09

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

  4. Liquid-phase synthesis of cobalt oxide nanoparticles.

    Science.gov (United States)

    Sinkó, Katalin; Szabó, Géza; Zrínyi, Miklós

    2011-05-01

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

  5. Improvement of a headspace solid phase microextraction-gas chromatography/mass spectrometry method for the analysis of wheat bread volatile compounds.

    Science.gov (United States)

    Raffo, Antonio; Carcea, Marina; Castagna, Claudia; Magrì, Andrea

    2015-08-07

    An improved method based on headspace solid phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME/GC-MS) was proposed for the semi-quantitative determination of wheat bread volatile compounds isolated from both whole slice and crust samples. A DVB/CAR/PDMS fibre was used to extract volatiles from the headspace of a bread powdered sample dispersed in a sodium chloride (20%) aqueous solution and kept for 60min at 50°C under controlled stirring. Thirty-nine out of all the extracted volatiles were fully identified, whereas for 95 other volatiles a tentative identification was proposed, to give a complete as possible profile of wheat bread volatile compounds. The use of an array of ten structurally and physicochemically similar internal standards allowed to markedly improve method precision with respect to previous HS-SPME/GC-MS methods for bread volatiles. Good linearity of the method was verified for a selection of volatiles from several chemical groups by calibration with matrix-matched extraction solutions. This simple, rapid, precise and sensitive method could represent a valuable tool to obtain semi-quantitative information when investigating the influence of technological factors on volatiles formation in wheat bread and other bakery products.

  6. Gas chromatography on wall-coated open-tubular columns with ionic liquid stationary phases.

    Science.gov (United States)

    Poole, Colin F; Lenca, Nicole

    2014-08-29

    Ionic liquids have moved from novel to practical stationary phases for gas chromatography with an increasing portfolio of applications. Ionic liquids complement conventional stationary phases because of a combination of thermophysical and solvation properties that only exist for ionic solvents. Their high thermal stability and low vapor pressure makes them suitable as polar stationary phases for separations requiring high temperatures. Ionic liquids are good solvents and can be used to expand the chemical space for separations. They are the only stationary phases with significant hydrogen-bond acidity in common use; they extend the hydrogen-bond basicity of conventional stationary phases; they are as dipolar/polarizable as the most polar conventional stationary phases; and some ionic liquids are significantly less cohesive than conventional polar stationary phases. Problems in column coating techniques and related low column performance, column activity, and stationary phase reactivity require further exploration as the reasons for these features are poorly understood at present.

  7. Preparation and evaluation of surface-bonded tricationic ionic liquid silica as stationary phases for high-performance liquid chromatography.

    Science.gov (United States)

    Qiao, Lizhen; Shi, Xianzhe; Lu, Xin; Xu, Guowang

    2015-05-29

    Two tricationic ionic liquids were prepared and then bonded onto the surface of supporting silica materials through "thiol-ene" click chemistry as new stationary phases for high-performance liquid chromatography. The obtained columns of tricationic ionic liquids were evaluated respectively in the reversed-phase liquid chromatography (RPLC) mode and hydrophilic interaction liquid chromatography (HILIC) mode, and possess ideal column efficiency of 80,000 plates/m in the RPLC mode with naphthalene as the test solute. The tricationic ionic liquid stationary phases exhibit good hydrophobic and shape selectivity to hydrophobic compounds, and RPLC retention behavior with multiple interactions. In the HILIC mode, the retention and selectivity were evaluated through the efficient separation of nucleosides and bases as well as flavonoids, and the typical HILIC retention behavior was demonstrated by investigating retention changes of hydrophilic solutes with water volume fraction in mobile phase. The results show that the tricationic ionic liquid columns possess great prospect for applications in analysis of hydrophobic and hydrophilic samples.

  8. Blue phase liquid crystal: strategies for phase stabilization and device development

    Directory of Open Access Journals (Sweden)

    Asiqur Rahman, Suhana Mohd Said and S Balamurugan

    2015-05-01

    Full Text Available The blue phase liquid crystal (BPLC is a highly ordered liquid crystal (LC phase found very close to the LC–isotropic transition. The BPLC has demonstrated potential in next-generation display and photonic technology due to its exceptional properties such as sub-millisecond response time and wide viewing angle. However, BPLC is stable in a very small temperature range (0.5–1 °C and its driving voltage is very high (~100 V. To overcome these challenges recent research has focused on solutions which incorporate polymers or nanoparticles into the blue phase to widen the temperature range from around few °C to potentially more than 60 °C. In order to reduce the driving voltage, strategies have been attempted by modifying the device structure by introducing protrusion or corrugated electrodes and vertical field switching mechanism has been proposed. In this paper the effectiveness of the proposed solution will be discussed, in order to assess the potential of BPLC in display technology and beyond.

  9. Breakup of metal jets penetrating a volatile liquid. Final report, October 1, 1991--February 28, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, J.P.

    1995-07-01

    In a loss of coolant accident, the core may become uncovered, causing the fuel pins to melt. The molten fuel would pour onto the plenum and collect on the reactor pressure vessel (RPV) lower head. The RPV internal structure includes one or more perforated plates in the lower plenum which would divide the molten fuel into small diameter streams or jets, which would break up as they penetrate the coolant in the lower plenum. The breakup of these jets would occur in two phases, each dominated by a distinct fragmentation mechanism. As a fuel jet first penetrates the coolant, a stagnation flow develops at its leading edge, causing the column to spread radially and eject molten fuel into the coolant. The jet fluid in the column is fragmented by pressure fluctuations due to the jet/ambient fluid relative motion, so that a steady jet is reduced to a field of falling drops below a critical depth called the breakup length. The present work includes analyses yielding simple correlations for jet breakup length and jet leading edge penetration.

  10. Anodized aluminum wire as a solid-phase microextraction fiber for rapid determination of volatile constituents in medicinal plant.

    Science.gov (United States)

    Gholivand, Mohammad Bagher; Piryaei, Marzieh; Abolghasemi, Mir Mahdi

    2011-09-02

    Headspace solid phase microextraction using anodized aluminum fiber in combination with capillary GC-MS was utilized as monitoring technique for the collection and detection of the volatile compounds of Echinophora platyloba DC. Experimental parameters, including the sample weight, extraction temperature, extraction time and humidity effect, desorption time and desorption temperature were examined and optimized. Using HS-SPME followed by GC-MS, 53 compounds were separated and identified in E. platyloba DC, which mainly included E-β ocimene (47.63%), R-D-decalactone (13.28%), α-pinene (7.43%) and nonane (6.71%). Compared with hydrodistillation (HD), HS-SPME, provides the advantages of a small amount of sample, timesaving, simplicity and cheapness. To the best of our knowledge, this is the first report on using anodized aluminum fiber in solid-phase microextraction coupled to headspace for the investigation of volatile fraction of medicinal plant. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Facile synthesis and properties of CdSe quantum dots in a novel two-phase liquid/liquid system

    Science.gov (United States)

    Wang, Jidong; Wang, Xiaoyu; Tang, Hengshan; Gao, Zehua; He, Shengquan; Ke, Dandan; Zheng, Yue; Han, Shumin

    2017-10-01

    High-quantity CdSe QDs were synthesized in a novel two-phase liquid/liquid system. This system, ODE/water was stable and as-used solvents were almost nontoxic. The methodology leading to the successful synthesis of CdSe QDs was a typical, one-pot approach and the obtained CdSe QDs with zinc-blende phase structure exhibited excellent optical properties, narrow size distribution, higher particle uniformity and crystallinity. The mechanism of nucleation and growth of CdSe QDs were discussed by the possible thermodynamic equilibrium existing in ODE/water interface. This two-phase liquid/liquid system would broaden the synthesis of other semiconductor QDs.

  12. Phase transformation and liquid density redistribution during solidification of Ni-based superalloy Inconel 718

    Directory of Open Access Journals (Sweden)

    Wang Ling

    2012-08-01

    Full Text Available The influences of chemical segregation and phase transformation on liquid density variation during solidification of Ni-based supperalloy Inconel 718 were investigated using SEM and EDS. It was found that significant segregation in liquid prompts high Nb phase to precipitate directly from liquid, which results in the redistribution of alloy elements and liquid density in their vicinity. The term “inter-precipitate liquid density” is therefore proposed and this concept should be applied to determine the solidification behavior of superalloy Inconel 718.

  13. Characterization of annular two-phase gas-liquid flows in microgravity

    Science.gov (United States)

    Bousman, W. Scott; Mcquillen, John B.

    1994-01-01

    A series of two-phase gas-liquid flow experiments were developed to study annular flows in microgravity using the NASA Lewis Learjet. A test section was built to measure the liquid film thickness around the perimeter of the tube permitting the three dimensional nature of the gas-liquid interface to be observed. A second test section was used to measure the film thickness, pressure drop and wall shear stress in annular microgravity two-phase flows. Three liquids were studied to determine the effects of liquid viscosity and surface tension. The result of this study provide insight into the wave characteristics, pressure drop and droplet entrainment in microgravity annular flows.

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

    Science.gov (United States)

    Zuend, A.; Di Stefano, A.

    2014-12-01

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

  15. Crosslinked polymeric ionic liquids as solid-phase microextraction sorbent coatings for high performance liquid chromatography.

    Science.gov (United States)

    Yu, Honglian; Merib, Josias; Anderson, Jared L

    2016-03-18

    Neat crosslinked polymeric ionic liquid (PIL) sorbent coatings for solid-phase microextraction (SPME) compatible with high-performance liquid chromatography (HPLC) are reported for the first time. Six structurally different PILs were crosslinked to nitinol supports and applied for the determination of select pharmaceutical drugs, phenolics, and insecticides. Sampling conditions including sample solution pH, extraction time, desorption solvent, desorption time, and desorption solvent volume were optimized using design of experiment (DOE). The developed PIL sorbent coatings were stable when performing extractions under acidic pH and remained intact in various organic desorption solvents (i.e., methanol, acetonitrile, acetone). The PIL-based sorbent coating polymerized from the IL monomer 1-vinyl-3-(10-hydroxydecyl) imidazolium chloride [VC10OHIM][Cl] and IL crosslinker 1,12-di(3-vinylbenzylimidazolium) dodecane dichloride [(VBIM)2C12] 2[Cl] exhibited superior extraction performance compared to the other studied PILs. The extraction efficiency of pharmaceutical drugs and phenolics increased when the film thickness of the PIL-based sorbent coating was increased while many insecticides were largely unaffected. Satisfactory analytical performance was obtained with limits of detection (LODs) ranging from 0.2 to 2 μg L(-1) for the target analytes. The accuracy of the analytical method was examined by studying the relative recovery of analytes in real water samples, including tap water and lake water, with recoveries varying from 50.2% to 115.9% and from 48.8% to 116.6%, respectively.

  16. Non-equilibrium phase transitions in a liquid crystal

    Science.gov (United States)

    Dan, K.; Roy, M.; Datta, A.

    2015-09-01

    The present manuscript describes kinetic behaviour of the glass transition and non-equilibrium features of the "Nematic-Isotropic" (N-I) phase transition of a well known liquid crystalline material N-(4-methoxybenzylidene)-4-butylaniline from the effects of heating rate and initial temperature on the transitions, through differential scanning calorimetry (DSC), Fourier transform infrared and fluorescence spectroscopy. Around the vicinity of the glass transition temperature (Tg), while only a change in the baseline of the ΔCp vs T curve is observed for heating rate (β) > 5 K min-1, consistent with a glass transition, a clear peak for β ≤ 5 K min-1 and the rapid reduction in the ΔCp value from the former to the latter rate correspond to an order-disorder transition and a transition from ergodic to non-ergodic behaviour. The ln β vs 1000/T curve for the glass transition shows convex Arrhenius behaviour that can be explained very well by a purely entropic activation barrier [Dan et al., Eur. Phys. Lett. 108, 36007 (2014)]. Fourier transform infrared spectroscopy indicates sudden freezing of the out-of-plane distortion vibrations of the benzene rings around the glass transition temperature and a considerable red shift indicating enhanced coplanarity of the benzene rings and, consequently, enhancement in the molecular ordering compared to room temperature. We further provide a direct experimental evidence of the non-equilibrium nature of the N-I transition through the dependence of this transition temperature (TNI) and associated enthalpy change (ΔH) on the initial temperature (at fixed β-values) for the DSC scans. A plausible qualitative explanation based on Mesquita's extension of Landau-deGennes theory [O. N. de Mesquita, Braz. J. Phys. 28, 257 (1998)] has been put forward. The change in the molecular ordering from nematic to isotropic phase has been investigated through fluorescence anisotropy measurements where the order parameter, quantified by the

  17. Non-equilibrium phase transitions in a liquid crystal.

    Science.gov (United States)

    Dan, K; Roy, M; Datta, A

    2015-09-07

    The present manuscript describes kinetic behaviour of the glass transition and non-equilibrium features of the "Nematic-Isotropic" (N-I) phase transition of a well known liquid crystalline material N-(4-methoxybenzylidene)-4-butylaniline from the effects of heating rate and initial temperature on the transitions, through differential scanning calorimetry (DSC), Fourier transform infrared and fluorescence spectroscopy. Around the vicinity of the glass transition temperature (Tg), while only a change in the baseline of the ΔCp vs T curve is observed for heating rate (β) > 5 K min(-1), consistent with a glass transition, a clear peak for β ≤ 5 K min(-1) and the rapid reduction in the ΔCp value from the former to the latter rate correspond to an order-disorder transition and a transition from ergodic to non-ergodic behaviour. The ln β vs 1000/T curve for the glass transition shows convex Arrhenius behaviour that can be explained very well by a purely entropic activation barrier [Dan et al., Eur. Phys. Lett. 108, 36007 (2014)]. Fourier transform infrared spectroscopy indicates sudden freezing of the out-of-plane distortion vibrations of the benzene rings around the glass transition temperature and a considerable red shift indicating enhanced coplanarity of the benzene rings and, consequently, enhancement in the molecular ordering compared to room temperature. We further provide a direct experimental evidence of the non-equilibrium nature of the N-I transition through the dependence of this transition temperature (TNI) and associated enthalpy change (ΔH) on the initial temperature (at fixed β-values) for the DSC scans. A plausible qualitative explanation based on Mesquita's extension of Landau-deGennes theory [O. N. de Mesquita, Braz. J. Phys. 28, 257 (1998)] has been put forward. The change in the molecular ordering from nematic to isotropic phase has been investigated through fluorescence anisotropy measurements where the order parameter, quantified by the

  18. 40 CFR 227.32 - Liquid, suspended particulate, and solid phases of a material.

    Science.gov (United States)

    2010-07-01

    ... MATERIALS Definitions § 227.32 Liquid, suspended particulate, and solid phases of a material. (a) For the... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Liquid, suspended particulate, and solid phases of a material. 227.32 Section 227.32 Protection of Environment ENVIRONMENTAL...

  19. Effect of heat and film thickness on a photoinduced phase transition in azobenzene liquid crystalline polyesters

    DEFF Research Database (Denmark)

    Sanchez, C; Alcala, R; Hvilsted, Søren

    2003-01-01

    The liquid crystal to isotropic phase transition induced with 488 nm light in films of liquid crystalline azobenzene polyesters has been studied as a function of temperature, light intensity, and film thickness. That phase transition is associated with the photoinduced trans-cis-trans isomerizati...

  20. Determination of Roxarsone in feeds using solid phase extraction and liquid chromatography with ultraviolet detection.

    Science.gov (United States)

    Sapp, R E; Davidson, S

    1993-01-01

    A method is presented for detection and quantitation of Roxarsone in poultry feed by liquid chromatography. The drug is extracted by phosphate buffer and determined by solid phase extraction and reversed-phase liquid chromatography. Recoveries of the sample spikes and fortified field samples agree closely with those obtained by the standard spectrophotometric method.

  1. NUMERICAL SIMULATION OF CHARGED GAS-LIQUID TWO PHASE JET FLOW IN ELECTROSTATIC SPRAYING

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Multi-fluid k-ε-kp two phase turbulence model is used to simulate charged gas-liquid two phase coaxial jet, which is the transorting flow field in electrostatic spraying. Compared with the results of experiment, charged gas-liquid twophase turbulence can be well predicted by this model.

  2. Groundwater cleanup by in-situ sparging. X. Air channeling model for biosparging of nonaqueous phase liquid

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, D.J.; Norris, R.D.; Clarke, A.N. [Eckenfelder Inc., Nashville, TN (United States)

    1996-06-01

    A column model is developed to simulate the removal and biodegradation of dissolved and nonaqueous phase liquid (NAPL) volatile organic compounds (VOCs) from contaminated aquifers by biosparging. The model assumes that the injected air moves through the aquifer in persistent channels and that NAPL must dissolve and move to these channels by diffusion and dispersion. The dependence of model results on several of the parameters of the model is investigated, and suggestions for optimizing biosparging system operations are made. The removal of NAPL VOCs of quite low solubility (such as alkanes) from smear zones below the water is modeled, and is found to be an extremely slow process. Drawing down the water table to below the smear zone by pumping is suggested as a possible solution.

  3. Relation between the Widom line and the dynamic crossover in systems with a liquid-liquid phase transition.

    Science.gov (United States)

    Xu, Limei; Kumar, Pradeep; Buldyrev, S V; Chen, S-H; Poole, P H; Sciortino, F; Stanley, H E

    2005-11-15

    We investigate, for two water models displaying a liquid-liquid critical point, the relation between changes in dynamic and thermodynamic anomalies arising from the presence of the liquid-liquid critical point. We find a correlation between the dynamic crossover and the locus of specific heat maxima C(P)(max) ("Widom line") emanating from the critical point. Our findings are consistent with a possible relation between the previously hypothesized liquid-liquid phase transition and the transition in the dynamics recently observed in neutron scattering experiments on confined water. More generally, we argue that this connection between C(P)(max) and dynamic crossover is not limited to the case of water, a hydrogen bond network-forming liquid, but is a more general feature of crossing the Widom line. Specifically, we also study the Jagla potential, a spherically symmetric two-scale potential known to possess a liquid-liquid critical point, in which the competition between two liquid structures is generated by repulsive and attractive ramp interactions.

  4. Centrifugal contactor with liquid mixing and flow control vanes and method of mixing liquids of different phases

    Science.gov (United States)

    Jubin, Robert T.; Randolph, John D.

    1991-01-01

    The invention is directed to a centrifugal contactor for solvent extraction systems. The centrifugal contactor is provided with an annular vertically oriented mixing chamber between the rotor housing and the rotor for mixing process liquids such as the aqueous and organic phases of the solvent extraction process used for nuclear fuel reprocessing. A set of stationary helically disposed vanes carried by the housing is in the lower region of the mixing chamber at a location below the process-liquid inlets for the purpose of urging the liquids in an upward direction toward the inlets and enhancing the mixing of the liquids and mass transfer between the liquids. The upper region of the mixing vessel above the inlets for the process liquids is also provided with a set helically disposed vanes carried by the housing for urging the process liquids in a downward direction when the liquid flow rates through the inlets are relatively high and the liquids contact the vane set in the upper region. The use of these opposing vane sets in the mixing zone maintains the liquid in the mixing zone at suitable levels.

  5. Alteration of gas phase ion polarizabilities upon hydration in high dielectric liquids

    OpenAIRE

    2013-01-01

    We investigate the modification of gas phase ion polarizabilities upon solvation in polar solvents and ionic liquids. To this aim, we develop a classical electrostatic theory of charged liquids composed of solvent molecules modeled as finite size dipoles, and embedding polarizable ions that consist of Drude oscillators. In qualitative agreement with ab-initio calculations of polar solvents and ionic liquids, the hydration energy of a polarizable ion in both type of dielectric liquid is shown ...

  6. Going full circle: phase-transition thermodynamics of ionic liquids.

    Science.gov (United States)

    Preiss, Ulrich; Verevkin, Sergey P; Koslowski, Thorsten; Krossing, Ingo

    2011-05-27

    We present the full enthalpic phase transition cycle for ionic liquids (ILs) as examples of non-classical salts. The cycle was closed for the lattice, solvation, dissociation, and vaporization enthalpies of 30 different ILs, relying on as much experimental data as was available. High-quality dissociation enthalpies were calculated at the G3 MP2 level. From the cycle, we could establish, for the first time, the lattice and solvation enthalpies of ILs with imidazolium ions. For vaporization, lattice, and dissociation enthalpies, we also developed new prediction methods in the course of our investigations. Here, as only single-ion values need to be calculated and the tedious optimization of an ion pair can be circumvented, the computational time is short. For the vaporization enthalpy, a very simple approach was found, using a surface term and the calculated enthalpic correction to the total gas-phase energy. For the lattice enthalpy, the most important constituent proved to be the calculated conductor-like screening model (COSMO) solvation enthalpy in the ideal electric conductor. A similar model was developed for the dissociation enthalpy. According to our assessment, the typical error of the lattice enthalpy would be 9.4 kJ mol(-1), which is less than half the deviation we get when using the (optimized) Kapustinskii equation or the recent volume-based thermodynamics (VBT) theory. In contrast, the non-optimized VBT formula gives lattice enthalpies 20 to 140 kJ mol(-1) lower than the ones we assessed in the cycle, because of the insufficient description of dispersive interactions. Our findings show that quantum-chemical calculations can greatly improve the VBT approaches, which were parameterized for simple, inorganic salts with ideally point-shaped charges. In conclusion, we suggest the term "augmented VBT", or "aVBT", to describe this kind of theoretical approach.

  7. A comparative study of solid and liquid non-aqueous phases for the biodegradation of hexane in two-phase partitioning bioreactors.

    Science.gov (United States)

    Hernández, María; Quijano, Guillermo; Thalasso, Frédéric; Daugulis, Andrew J; Villaverde, Santiago; Muñoz, Raúl

    2010-08-01

    A comparative study of the performance of solid and liquid non-aqueous phases (NAPs) to enhance the mass transfer and biodegradation of hexane by Pseudomonas aeruginosa in two-phase partitioning bioreactors (TPPBs) was undertaken. A preliminary NAP screening was thus carried out among the most common solid and liquid NAPs used in pollutant biodegradation. The polymer Kraton G1657 (solid) and the liquid silicone oils SO20 and SO200 were selected from this screening based on their biocompatibility, resistance to microbial attack, non-volatility and high affinity for hexane (low partition coefficient: K = C(g)/C(NAP), where C(g) and C(NAP) represent the pollutant concentration in the gas phase and NAP, respectively). Despite the three NAPs exhibited a similar affinity for hexane (K approximately 0.0058), SO200 and SO20 showed a superior performance to Kraton G1657 in terms of hexane mass transfer and biodegradation enhancement. The enhanced performance of SO200 and SO20 could be explained by both the low interfacial area of this solid polymer (as a result of the large size of commercial beads) and by the interference of water on hexane transfer (observed in this work). When Kraton G1657 (20%) was tested in a TPPB inoculated with P. aeruginosa, steady state elimination capacities (ECs) of 5.6 +/- 0.6 g m(-3) h(-1) were achieved. These values were similar to those obtained in the absence of a NAP but lower compared to the ECs recorded in the presence of 20% of SO200 (10.6 +/- 0.9 g m(-3) h(-1)). Finally, this study showed that the enhancement in the transfer of hexane supported by SO200 was attenuated by limitations in microbial activity, as shown by the fact that the ECs in biotic systems were far lower than the maximum hexane transfer capacity recorded under abiotic conditions.

  8. Terahertz saturable absorbers from liquid phase exfoliation of graphite

    Science.gov (United States)

    Bianchi, Vezio; Carey, Tian; Viti, Leonardo; Li, Lianhe; Linfield, Edmund H.; Davies, A. Giles; Tredicucci, Alessandro; Yoon, Duhee; Karagiannidis, Panagiotis G.; Lombardi, Lucia; Tomarchio, Flavia; Ferrari, Andrea C.; Torrisi, Felice; Vitiello, Miriam S.

    2017-06-01

    Saturable absorbers (SA) operating at terahertz (THz) frequencies can open new frontiers in the development of passively mode-locked THz micro-sources. Here we report the fabrication of THz SAs by transfer coating and inkjet printing single and few-layer graphene films prepared by liquid phase exfoliation of graphite. Open-aperture z-scan measurements with a 3.5 THz quantum cascade laser show a transparency modulation ~80%, almost one order of magnitude larger than that reported to date at THz frequencies. Fourier-transform infrared spectroscopy provides evidence of intraband-controlled absorption bleaching. These results pave the way to the integration of graphene-based SA with electrically pumped THz semiconductor micro-sources, with prospects for applications where excitation of specific transitions on short time scales is essential, such as time-of-flight tomography, coherent manipulation of quantum systems, time-resolved spectroscopy of gases, complex molecules and cold samples and ultra-high speed communications, providing unprecedented compactness and resolution.

  9. GaSb film growth by liquid phase epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Cruz, M.L.; Martinez-Juarez, J.; Lopez-Salazar, P. [CIDS-ICUAP, BUAP, Av. 14 Sur y San Claudio, C.U. Edif.103C, Col. Sn Manuel, C.P. 72570, Puebla, Pue. (Mexico); Diaz, G.J. [Centro de Investigacion y Estudios Avanzados, IPN, Av. IPN 2508, Col. Sn. Pedro Zacatenco, C.P. 07360, D.F. (Mexico)

    2010-04-15

    Doped GaSb (Gallium Antimonide) films on p-GaSb substrates have been obtained by means of a low-cost and fast-growth method: the liquid phase epitaxy (LPE) technique. The growth temperature was 400 C, and the growth time was varied between1 and 5 min. Characterization of the films was performed by means of high resolution X-ray Diffraction, low temperature-photoluminescence and current-voltage curve measurements. The X-ray diffraction pattern confirms a zincblende-type crystal structure with a high-thin peak centred at 30.36 . The PL spectra at 27 K allowed to confirm the band-gap energy to be 0.8 eV and the I-V curves presented a PN junction behavior which corresponds to the obtained structured. Metal contacts of Au-Zn and Au-Ge were placed to perform electrical characterization (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Restrictive liquid-phase diffusion and reaction in bidispersed catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.Y.; Seader, J.D. (Utah Univ., Salt Lake City, UT (United States). Dept. of Chemical Engineering); Tsai, C.H.; Massoth, F.E. (Utah Univ., Salt Lake City, UT (United States). Dept. of Fuels Engineering)

    1991-08-01

    In this paper, the effect of bidispersed pore-size distribution on liquid-phase diffusion and reaction in NiMo/Al{sub 2}O{sub 3} catalysts is investigated by applying two bidispersed-pore-structure models, the random-pore model and a globular-structure model, to extensive experimental data, which were obtained from sorptive diffusion measurements at ambient conditions and catalytic reaction rate measurements on nitrogen-containing compounds. Transport of the molecules in the catalysts was found to be controlled by micropore diffusion, in accordance with the random-pore model, rather than macropore diffusion as predicted by the globular-structure model. A qualitative criterion for micropore-diffusion control is proposed: relatively small macroporosity and high catalyst pellet density. Since most hydrotreating catalysts have high density, diffusion in these types of catalysts may be controlled by micropore diffusion. Accordingly, it is believed in this case that increasing the size of micropores may be more effective to reduce intraparticle diffusion resistance than incorporating macropores alone.

  11. Homogeneous Liquid Phase Transfer of Graphene Oxide into Epoxy Resins.

    Science.gov (United States)

    Amirova, Lyaysan; Surnova, Albina; Balkaev, Dinar; Musin, Delus; Amirov, Rustem; Dimiev, Ayrat M

    2017-04-05

    The quality of polymer composite materials depends on the distribution of the filler in the polymer matrix. Due to the presence of the oxygen functional groups, graphene oxide (GO) has a strong affinity to epoxy resins, providing potential opportunity for the uniform distribution of GO sheets in the matrix. Another advantage of GO over its nonoxidized counterpart is its ability to exfoliate to single-atomic-layer sheets in water and in some organic solvents. However, these advantages of GO have not yet been fully realized due to the lack of the methods efficiently introducing GO into the epoxy resin. Here we develop a novel homogeneous liquid phase transfer method that affords uniform distribution, and fully exfoliated condition of GO in the polymer matrix. The most pronounced alteration of properties of the cured composites is registered at the 0.10%-0.15% GO content. Addition of as little as 0.10% GO leads to the increase of the Young's modulus by 48%. Moreover, we demonstrate successful introduction of GO into the epoxy matrix containing an active diluent-modifier; this opens new venues for fabrication of improved GO-epoxy-modifier composites with a broad range of predesigned properties. The experiments done on reproducing the two literature methods, using alternative GO introduction techniques, lead to either decrease or insignificant increase of the Young's modulus of the resulting GO-epoxy composites.

  12. Dynamic headspace liquid-phase microextraction of alcohols.

    Science.gov (United States)

    Saraji, Mohammad

    2005-01-07

    A method was developed using dynamic headspace liquid-phase microextraction and gas chromatography-mass spectrometry for extraction and determination of 9 alcohols from water samples. Four different solvents, hexyl acetate, n-octanol, o-xylene and n-decane were studied as extractants. The analytes were extracted using 0.8 microl of n-octanol from the headspace of a 2 ml sample solution. The effect of sampling volume, solvent volume, sample temperature, syringe plunger withdrawal rate and ionic strength of the solution on the extraction performance were studied. A semiautomated system including a variable speed stirring motor was used to ensure a uniform movement of syringe plunger through the barrel. The method provided a fairly good precision for all compounds (5.5-9.3%), except methanol (16.4%). Detection limits were found to be between 1 and 97 microg/l within an extraction time of approximately 9.5 min under GC-MS in full scan mode.

  13. Determination of hydrogen sulfide and volatile thiols in air samples by mercury probe derivatization coupled with liquid chromatography-atomic fluorescence spectrometry.

    Science.gov (United States)

    Bramanti, Emilia; D'Ulivo, Lucia; Lomonte, Cristina; Onor, Massimo; Zamboni, Roberto; Raspi, Giorgio; D'Ulivo, Alessandro

    2006-10-02

    A new procedure is proposed for the sampling and storage of hydrogen sulphide (H2S) and volatile thiols (methanethiol or methyl mercaptan, ethanethiol and propanethiol) for their determination by liquid chromatography. The sampling procedure is based on the trapping/pre-concentration of the analytes in alkaline aqueous solution containing an organic mercurial probe p-hydroxymercurybenzoate, HO-Hg-C6H4-COO- (PHMB), where they are derivatized to stable PHMB complexes based on mercury-sulfur covalent bonds. PHMB complexes are separated on a C18 reverse phase column, allowing their determination by liquid chromatography coupled with sequential non-selective UV-vis (DAD) and mercury specific (chemical vapor generation atomic fluorescence spectrometry, CVGAFS) on-line detectors. PHMB complexes, S(PHMB)2CH3S-PHMB, C2H5S-PHMB and C3H7S-PHMB, are stable alt least for 12 h at room temperature and for 3 months if stored frozen (-20 degrees C). The best analytical figures of merits in the optimized conditions were obtained by CVGAFS detection, with detection limits (LODc) of 9.7 microg L(-1) for H2S, 13.7 microg L(-1) for CH(3)SH, 17.7 microg L(-1) for C2H5SH and 21.7 microg L(-1) for C3H7SH in the trapping solution in form of RS-PHMB complexes, the relative standard deviation (R.S.D.) ranging between 1.0 and 1.5%, and a linear dynamic range (LDR) between 10 and 9700 microg L(-1). Conventional UV absorbance detectors tuned at 254 nm can be employed as well with comparable R.S.D. and LDR, but with LODc one order of magnitude higher than AFS detector and lower specificity. The sampling procedure followed by LC-DAD-CVGAFS analysis has been validated, as example, for H2S determination by a certified gas permeation tube as a source of 3.071+/-0.154 microg min(-1) of H2S, giving a recovery of 99.8+/-7% and it has been applied to the determination of sulfur compounds in real gas samples (biogas and the air of a plant for fractional distillation of crude oil).

  14. Determination of hydrogen sulfide and volatile thiols in air samples by mercury probe derivatization coupled with liquid chromatography-atomic fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Bramanti, Emilia [Italian National Research Council, CNR-Istituto per i Processi Chimico-Fisici, Laboratory of Instrumental Analytical Chemistry, Via G. Moruzzi 1, 56124 Pisa (Italy)]. E-mail: emilia@ipcf.cnr.it; D' Ulivo, Lucia [Italian National Research Council, CNR-Istituto per i Processi Chimico-Fisici, Laboratory of Instrumental Analytical Chemistry, Via G. Moruzzi 1, 56124 Pisa (Italy); Lomonte, Cristina [Italian National Research Council, CNR-Istituto per i Processi Chimico-Fisici, Laboratory of Instrumental Analytical Chemistry, Via G. Moruzzi 1, 56124 Pisa (Italy); Ambiente s.c.r.l., Via Frassina 21, 54033, Carrrara, Massa (Italy); Onor, Massimo [Italian National Research Council, CNR-Istituto per i Processi Chimico-Fisici, Laboratory of Instrumental Analytical Chemistry, Via G. Moruzzi 1, 56124 Pisa (Italy); Zamboni, Roberto [Department of Chemistry and Industrial Chemistry, University of Pisa, Via Risorgimento 35, 56126 Pisa (Italy); Raspi, Giorgio [Italian National Research Council, CNR-Istituto per i Processi Chimico-Fisici, Laboratory of Instrumental Analytical Chemistry, Via G. Moruzzi 1, 56124 Pisa (Italy); D' Ulivo, Alessandro [Italian National Research Council, CNR-Istituto per i Processi Chimico-Fisici, Laboratory of Instrumental Analytical Chemistry, Via G. Moruzzi 1, 56124 Pisa (Italy)

    2006-10-02

    A new procedure is proposed for the sampling and storage of hydrogen sulphide (H{sub 2}S) and volatile thiols (methanethiol or methyl mercaptan, ethanethiol and propanethiol) for their determination by liquid chromatography. The sampling procedure is based on the trapping/pre-concentration of the analytes in alkaline aqueous solution containing an organic mercurial probe p-hydroxymercurybenzoate, HO-Hg-C{sub 6}H{sub 4}-COO{sup -} (PHMB), where they are derivatized to stable PHMB complexes based on mercury-sulfur covalent bonds. PHMB complexes are separated on a C{sub 18} reverse phase column, allowing their determination by liquid chromatography coupled with sequential non-selective UV-vis (DAD) and mercury specific (chemical vapor generation atomic fluorescence spectrometry, CVGAFS) on-line detectors. PHMB complexes, S(PHMB){sub 2}CH{sub 3}S-PHMB, C{sub 2}H{sub 5}S-PHMB and C{sub 3}H{sub 7}S-PHMB, are stable alt least for 12 h at room temperature and for 3 months if stored frozen (-20 deg. C). The best analytical figures of merits in the optimized conditions were obtained by CVGAFS detection, with detection limits (LODc) of 9.7 {mu}g L{sup -1} for H{sub 2}S, 13.7 {mu}g L{sup -1} for CH{sub 3}SH, 17.7 {mu}g L{sup -1} for C{sub 2}H{sub 5}SH and 21.7 {mu}g L{sup -1} for C{sub 3}H{sub 7}SH in the trapping solution in form of RS-PHMB complexes, the relative standard deviation (R.S.D.) ranging between 1.0 and 1.5%, and a linear dynamic range (LDR) between 10 and 9700 {mu}g L{sup -1}. Conventional UV absorbance detectors tuned at 254 nm can be employed as well with comparable R.S.D. and LDR, but with LODc one order of magnitude higher than AFS detector and lower specificity. The sampling procedure followed by LC-DAD-CVGAFS analysis has been validated, as example, for H{sub 2}S determination by a certified gas permeation tube as a source of 3.071 {+-} 0.154 {mu}g min{sup -1} of H{sub 2}S, giving a recovery of 99.8 {+-} 7% and it has been applied to the determination of

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

    Science.gov (United States)

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

    2016-04-01

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

  16. Applications of Solid-Phase Microextraction and Gas Chromatography/Mass Spectrometry (SPME-GC/MS in the Study of Grape and Wine Volatile Compounds

    Directory of Open Access Journals (Sweden)

    Annarita Panighel

    2014-12-01

    Full Text Available Volatile compounds are responsible for the wine “bouquet”, which is perceived by sniffing the headspace of a glass, and of the aroma component (palate-aroma of the overall flavor, which is perceived on drinking. Grape aroma compounds are transferred to the wine and undergo minimal alteration during fermentation (e.g., monoterpenes and methoxypyrazines; others are precursors of aroma compounds which form in winemaking and during wine aging (e.g., glycosidically-bound volatile compounds and C13-norisoprenoids. Headspace solid phase microextraction (HS-SPME is a fast and simple technique which was developed for analysis of volatile compounds. This review describes some SPME methods coupled with gas chromatography/mass spectrometry (GC/MS used to study the grape and wine volatiles.

  17. Research of Characteristics of Gas-liquid Two-phase Pressure Drop in Microreactor

    Directory of Open Access Journals (Sweden)

    Li Dan

    2015-01-01

    Full Text Available With the research system of nitrogen and deionized water, this paper researches the pressure drop of gas-liquid two-phase flow in the circular microchannel with an inner diameter which is respectively 0.9mm and 0.5mm, analyzes the effect of microchannel diameter on gas-liquid two-phase frictional pressure drop in the microchannel reactor, and compares with the result of frictional pressure drop and the predicting result of divided-phase flow pattern. The result shows that, the gas-liquid two-phase frictional pressure drop in the microchannel significantly increases with the decreasing microchannel diameter; Lockhart-Martinelli relationship in divided-phase flow pattern can preferably predict the gas-liquid two-phase frictional pressure drop in the microchannel, but the Tabular constant needs to be corrected.

  18. Solid-phase microextraction and gas chromatography-mass spectrometry of volatile compounds from avocado puree after microwave processing.

    Science.gov (United States)

    López, Mercedes G; Guzmán, G R; Dorantes, A L

    2004-05-14

    Microwave processing offers an alternative to blanch fruits and vegetables, since the application of high temperature and short time often results in minimum damage. An experimental design was used to investigate the effect of microwave time, pH, and avocado leaves (independent variables) on avocado flavor (response) using solid-phase microextraction (SPME)-GC-MS. Among the fully characterized flavor volatiles, 19 compounds were derived from lipid oxidation and only 4 from the avocado leaves. The main components derived from lipids were aldehydes, ketones and alcohols. Terpenoids, estragole, and 2-hexenal [E] were volatiles derived from avocado leaves. When leaves were added to fresh and microwaved avocado terpenoids and 2-hexenal [E]/hexanal ratio increased, this behavior was considered to have a positive effect on the sensorial quality of the product. From the statistical analysis of the experimental design, it was possible to determinate that the most important factors influencing the abundance of flavor compounds derived from lipids were microwave time and pH. Maximum values of these compounds were detected at high levels of microwave time and low values of pH. On the other hand, response surface of terpenoids and estragole showed an increment when microwave time and avocado leaf was increased. The region of optimum response was 30 s microwave time, pH 5.5, and 1% of avocado leaf.

  19. Optimization of the extraction conditions of the volatile compounds from chili peppers by headspace solid phase micro-extraction.

    Science.gov (United States)

    Junior, Stanislau Bogusz; de Marchi Tavares de Melo, Arlete; Zini, Cláudia Alcaraz; Godoy, Helena Teixeira

    2011-05-27

    A method involving headspace-solid phase micro-extraction (HS-SPME), gas chromatography with flame ionization detection (GC-FID) and gas chromatography with mass spectrometry (GC-MS) was developed and optimized to investigate the volatile composition of Capsicum chili peppers. Five SPME fibers were tested for extraction: carboxen/polydimethylsiloxane (CAR/PDMS-75μm), polydimethylsiloxane (PDMS-100μm), divinylbenzene/polydimethylsiloxane (DVB/PDMS-65μm), carbowax/divinylbenzene (CW/DVB-70μm), and divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS-50/30μm), the last of which was shown to be the most efficient fiber to trap the volatile compounds. Optimization of the extraction conditions was carried out using multivariate strategies such as factorial design and response surface methodology. Eighty three compounds were identified by GC-MS when using the optimized extraction conditions, the majority of which were esters. Copyright © 2011 Elsevier B.V. All rights reserved.

  20. Ionic liquids as stationary phases in gas chromatography--an LSER investigation of six commercial phases and some applications.

    Science.gov (United States)

    Weber, Waldemar; Andersson, Jan T

    2014-09-01

    The separation properties of six novel stationary phases for gas chromatography, commercially available from Sigma-Aldrich (Supelco) and based on ionic liquids (ILs), were investigated. The linear solvation energy relationship model (LSER) was used to describe the molecular interactions between these stationary phases and 30 solutes. The solutes belong to different groups of compounds, like haloalkanes, alcohols, ketones, aromatics, aliphatics, and others. A good description of different interactions, as described by the LSER model, could be achieved. The calculated values of system constants for the ionic liquid phases were compared with constants of commonly used standard phases like a 5 % phenyl/95 % dimethyl siloxane and a polyethylene glycol phase. The solute descriptors are in good agreement with those found by previous authors who have used the LSER model for 44 different ionic liquids as stationary phase. The experiments were carried out at two temperatures to evaluate the influence on the phase parameters and separation characteristics. The interactions of different functional groups with the IL phases are discussed. These novel IL phases are a promising replacement of or an addition to common polar phases. Based on the evaluated phase properties, several possibilities for applications of these novel phases are shown.

  1. Continuous fixed-bed gas-phase hydroformylation using supported ionic liquid-phase (SILP) Rh catalysts

    DEFF Research Database (Denmark)

    Riisager, Anders; Wasserscheid, Peter; Van Hal, R.

    2003-01-01

    Continuous flow gas-phase hydroformylation of propene was performed using novel supported ionic liquid-phase (SILP) catalysts containing immobilized Rh complexes of the biphosphine ligand sulfoxantphos in the ionic liquids 1-n-butyl-3-methylimidazolium hexafluorophosphate and halogen-free 1-n......-butyl-3-methylimidazolium n-octylsulfate on silica support. The Rh-sulfoxantphos SILP catalysts proved to be more regioselective than catalysts without ligand and the analogous ionic liquid-free catalysts, giving up to 96% linear product. Furthermore, the performance of the catalysts was generally...

  2. Phase Behavior of Mixtures of Ionic Liquids and Organic Solvents

    DEFF Research Database (Denmark)

    Abildskov, Jens; Ellegaard, Martin Dela; O’Connell, J.P.

    2010-01-01

    A corresponding-states form of the generalized van der Waals equation, previously developed for mixtures of an ionic liquid and a supercritical solute, is here extended to mixtures including an ionic liquid and a solvent (water or organic). Group contributions to characteristic parameters...... solvents. Here we show results for heavier and more-than-sparingly solutes such as carbon dioxide and propane in ionic liquids....

  3. Dynamic liquid phase nanoextraction coupled to GC/MS for rapid analysis of methoxyacetophenone and anisaldehyde isomers in urine.

    Science.gov (United States)

    Wu, Hui-Fen; Yen, Jyh-Hao

    2008-07-01

    This study introduces a novel extraction technique in the nanoscale and challenges the limits of solvent extraction in the GC/MS using electronic ionization (EI) method for quantitative determination of six methoxyacetophenone (MAP) and anisaldehye (AAH) isomers in one drop of water and urine. This technique is termed as dynamic liquid phase nanoextraction (DLPNE). The optimum parameters for the DLPNE technique were: selection of solvent, toluene; sampling volume, 0.44 microL; dwell time, 2 s; number of sampling, 15; extraction time, 1.5 min; volume of extraction solvent, 60 nL; and no salt addition. The LODs for this technique were 5-20 ng/mL. The RSDs were in the range of 9.7-12.6% (n = 6). The linear dynamic range of the calibration curve of DLPNE is from 0.02 to 0.5 microg/mL with correlation coefficient (r(2)) >0.9705. The advantages of the DLPNE technique are rapidity, ease of operation, simple device, and extremely little solvent and sample consumption. This technique was also compared with the static liquid phase nanoextraction (SLPNE) while the SLPNE failed to detect any signal for the six isomers. We believe that this technique can be very useful for the detection of volatile organic compounds in environmental science from microscale of water or it can be applied to clinical or pharmaceutical application such as diagnosis of microamount of urine or blood samples by GC/MS.

  4. Sterol structure determines the separation of phases and the curvature of the liquid-ordered phase in model membranes.

    Science.gov (United States)

    Bacia, Kirsten; Schwille, Petra; Kurzchalia, Teymuras

    2005-03-01

    The existence of lipid rafts in biological membranes in vivo is still debated. In contrast, the formation of domains in model systems has been well documented. In giant unilamellar vesicles (GUVs) prepared from ternary mixtures of dioleoyl-phosphatidylcholine/sphingomyelin/cholesterol, a clear separation of liquid-disordered and sphingomyelin-enriched, liquid-ordered phases could be observed. This phase separation can lead to the fission of the liquid-ordered phase from the vesicle. Here we show that in cholesterol-containing GUVs, the phase separation can involve dynamic redistribution of lipids from one phase into another as a result of a cross-linking perturbation. We found that the molecular structure of a sterol used for the preparation of GUVs determines (i) its ability to induce phase separation and (ii) the curvature (positive or negative) of the formed liquid-ordered phase. As a consequence, the latter can pinch off to the outside or inside of the vesicle. Remarkably, some mixtures of sterols induce liquid-ordered domains exhibiting both positive and negative curvature, which can lead to a new type of budding behavior in GUVs. Our findings could have implications for the role of sterols in various cell-biological processes such as budding of secretory vesicles, endocytosis, or formation of multivesicular bodies.

  5. Phase interface effects in the total enthalpy-based lattice Boltzmann model for solid-liquid phase change

    Science.gov (United States)

    Huang, Rongzong; Wu, Huiying

    2015-08-01

    In this paper, phase interface effects, including the differences in thermophysical properties between solid and liquid phases and the numerical diffusion across phase interface, are investigated for the recently developed total enthalpy-based lattice Boltzmann model for solid-liquid phase change, which has high computational efficiency by avoiding iteration procedure and linear equation system solving. For the differences in thermophysical properties (thermal conductivity and specific heat) between solid and liquid phases, a novel reference specific heat is introduced to improve the total enthalpy-based lattice Boltzmann model, which makes the thermal conductivity and specific heat decoupled. Therefore, the differences in thermal conductivity and specific heat can be handled by the dimensionless relaxation time and equilibrium distribution function, respectively. As for the numerical diffusion across phase interface, it is revealed for the first time and found to be induced by solid-liquid phase change. To reduce such numerical diffusion, multiple-relaxation-time collision scheme is exploited, and a special value (one fourth) for the so-called "magic" parameter, a combination of two relaxation parameters, is found. Numerical tests show that the differences in thermophysical properties can be correctly handled and the numerical diffusion across phase interface can be dramatically reduced. Finally, theoretical analyses are carried out to offer insights into the roles of the reference specific heat and "magic" parameter in the treatments of phase interface effects.

  6. Simultaneous determination of volatile and non-volatile nitrosamines in processed meat products by liquid chromatography tandem mass spectrometry using atmospheric pressure chemical ionisation and electrospray ionisation.

    Science.gov (United States)

    Herrmann, S S; Duedahl-Olesen, L; Granby, K

    2014-02-21

    A sensitive, selective and generic method has been developed for the simultaneous determination of the contents (μgkg(-1) range) of both volatile nitrosamines (VNA) and non-volatile nitrosamines (NVNA) in processed meat products. The extraction procedure only requires basic laboratory equipment and a small volume of organic solvent. Separation and quantification were performed by the developed LC-(APCI/ESI)MS/MS method. The method was validated using spiked samples of three different processed meat products. Satisfactory recoveries (50-130%) and precisions (2-23%) were obtained for eight VNA and six NVNAs with LODs generally between 0.2 and 1μgkg(-1), though for a few analyte/matrix combinations higher LODs were obtained (3 to 18μgkg(-1)). The validation results show that results obtained for one meat product is not always valid for other meat products. We were not able to obtain satisfactory results for N-nitrosohydroxyproline (NHPRO), N-nitrosodibenzylamine (NDBzA) and N-nitrosodiphenylamine (NDPhA). Application of the APCI interface improved the sensitivity of the method, because of less matrix interference, and gave the method a wider scope, as some NAs were ionisable only by APCI. However, it was only possible to ionize N-nitroso-thiazolidine-4-carboxylic acid (NTCA) and N-nitroso-2-methyl-thiazolidine-4-carboxylic acid (NMTCA) by ESI. The validated method was applied for the analysis of processed meat products and contents of N-nitrosodimethylamine (NDMA), N-nitrosopyrrolidine (NPYR), N-nitrosomethylaniline (NMA), N-nitrosoproline (NPRO), NTCA, and NMTCA were found in one or several nitrite cured meat products, whereas none were detected in non-nitrite cured bacon.

  7. A Liquid-Liquid Thermoelectric Heat Exchanger as a Heat Pump for Testing Phase Change Material Heat Exchangers

    Science.gov (United States)

    Sheth, Rubik B.; Makinen, Janice; Le, Hung V.

    2016-01-01

    The primary objective of the Phase Change HX payload on the International Space Station (ISS) is to test and demonstrate the viability and performance of Phase Change Material Heat Exchangers (PCM HX). The system was required to pump a working fluid through a PCM HX to promote the phase change material to freeze and thaw as expected on Orion's Multipurpose Crew Vehicle. Due to limitations on ISS's Internal Thermal Control System, a heat pump was needed on the Phase Change HX payload to help with reducing the working fluid's temperature to below 0degC (32degF). This paper will review the design and development of a TEC based liquid-liquid heat exchanger as a way to vary to fluid temperature for the freeze and thaw phase of the PCM HX. Specifically, the paper will review the design of custom coldplates and sizing for the required heat removal of the HX.

  8. A free energy study of the liquid-liquid phase transition of the Jagla two-scale potential

    Indian Academy of Sciences (India)

    FRANCESCO RICCI; PABLO G DEBENEDETTI

    2017-07-01

    A fundamental understanding of pure-component liquid-liquid phase separation in network-forming fluids remains an open challenge. While considerable progress has been recently made in demonstrating the existence of such a phase transition in some models via rigorous free energy calculations, it remains unclear what aspects of a model are sufficient, necessary, and/or prohibited in order for it to exhibit a liquid-liquid phase transition (LLPT). Among the simplest models capable of producing water-like anomalies is the sphericallysymmetrytwo-scale Jagla potential, for which an LLPT has been identified via equation of state calculations. In this work, we perform rigorous free energy calculations to demonstrate the existence of an LLPT in the Jagla model. We also utilize finite-size scaling analysis to calculate the surface tension associated with the LLPT.In addition to the thermodynamics of the model, we investigate the relaxation times for density and bondorientational order in both liquid phases and show that, contrary to assertions in the literature, the characteristic relaxation time of bond-orientational order is not orders of magnitude slower than that of density. To the contrary, we actually identify conditions for which density is the slowly relaxing order parameter. In addition to the original parameterization of the Jagla model, we provide in the “Appendix” preliminary free energy surface calculations for select parameterizations of the generalized family of Jagla potentials spanning from the original (anomalous,water-like) Jagla model to the Lennard-Jones model. These calculations indicate that, as the parameterization moves towards the Lennard-Jones limit, the LLPT disappears within the range of parametersexplored. Throughout the paper, we compare our results for the Jagla model with those found in the literature for the ST2 model of water in order to emphasize key similarities and differences between two models that exhibit pure-component liquid-liquid

  9. Rapid removal of nitrobenzene in a three-phase ozone loaded system with gas-liquid-liquid

    Science.gov (United States)

    Li, Shiyin; Zhu, Jiangpeng; Wang, Guoxiang; Ni, Lixiao; Zhang, Yong; Green, Christopher T.

    2015-01-01

    This study explores the removal rate of nitrobenzene (NB) using a new gas-liquid-liquid (G-L-L) three-phase ozone loaded system consisting of a gaseous ozone, an aqueous solvent phase, and a fluorinated solvent phase (perfluorodecalin, or FDC). The removal rate of NB was quantified in relation to six factors including 1) initial pH, 2) initial NB dosage, 3) gaseous ozone dosage, 4) free radical scavenger, 5) FDC pre-aerated gaseous ozone, and 6) reuse of FDC. The NB removal rate is positively affected by the first three factors. Compared with the conventional gas-liquid (water) (G-L) two-phase ozonation system, the free radical scavenger (tertiary butyl alcohol) has much less influence on the removal rate of NB in the G-L-L system. The FDC loaded ozone acts as an ozone reservoir and serves as the main reactive phase in the G-L-L three-phase system. The reuse of FDC has little influence on the removal rate of NB. These experimental results suggest that the oxidation efficiency of ozonation in the G-L-L three-phase system is better than that in the conventional G-L two-phase system.

  10. Application of hollow fiber liquid phase microextraction and dispersive liquid–liquid microextraction techniques in analytical toxicology

    Directory of Open Access Journals (Sweden)

    Vahid Sharifi

    2016-04-01

    Full Text Available The recent developments in hollow fiber liquid phase microextraction and dispersive liquid–liquid microextraction are reviewed. Applications of these newly emerging developments in extraction and preconcentration of a vast category of compounds including heavy metals, pesticides, pharmaceuticals and abused drugs in complex matrices (environmental and biological matrices are reviewed and discussed. The new developments in these techniques including the use of solvents lighter than water, ionic liquids and supramolecular solvents are also considered. Applications of these new solvents reduce the use of toxic solvents and eliminate the centrifugation step, which reduces the extraction time.

  11. Solid-phase microcolumn extraction and gas chromatography-mass spectrometry identification of volatile organic compounds emitted by paper.

    Science.gov (United States)

    Hrivnák, Ján; Tölgyessy, Peter; Figedyová, Sona; Katuscák, Svetozár

    2009-11-15

    A rapid non-destructive sampling technique for the analysis of volatile organic compounds (VOCs) emitted by paper sheets is described. A capillary, which is connected to a microcolumn packed with Tenax TA, is inserted between two sheets at the centre of a paper stack encapsulated inside a PET/Al/PE composite foil. The other end of the microcolumn is connected to a gas-tight syringe and an appropriate volume of gaseous phase is aspirated. The microcolumn is then thermally desorbed in a modified GC inlet (modification is presented) and analysed by gas chromatography-mass spectrometry (GC-MS). In the chromatogram from the analysis of artificially aged paper sample 21 compounds were identified. Advantages of the method including the short sampling time (1 min), simplicity and economic aspect are discussed.

  12. Liquid Swine Manure Can Kill Verticillium dahliae Microsclerotia in Soil by Volatile Fatty Acid, Nitrous Acid, and Ammonia Toxicity.

    Science.gov (United States)

    Conn, Kenneth L; Tenuta, Mario; Lazarovits, George

    2005-01-01

    ABSTRACT In previous studies, liquid swine manure (LSM) was sometimes shown to reduce Verticillium wilt of potato caused by Verticillium dahliae. We also observed that microsclerotia of this fungus died within 1 day, or between 3 and 6 weeks, after addition of LSM to some acid soils and within 1 week in some alkaline soils. In this study, we demonstrated that a volatile fatty acid (VFA) mixture with an identical concentration of VFAs as that found in an effective LSM reduced germination in an acid soil (pH 5.1) to the same extent as the LSM after 1 day of exposure. Germination was reduced by 45, 75, and 90% in the 10, 20, and 40% ([wt/wt] soil moisture) treatments, respectively, with the latter being equivalent to an application of 80 hl/ha. Addition to this acid soil of 19 LSMs (30% [wt/wt] soil moisture) collected from different producers resulted in complete kill of microsclerotia with 12 manures. Effective manures had a total concentration of nonionized forms of VFAs in soil solution of 2.7 mM or higher. In some acid soils (pH 5.8), addition of LSM (40% [wt/wt] soil moisture) did not kill microsclerotia until 3 to 6 weeks later. Here, a reduction in viability of microsclerotia was attributed to the accumulation of 0.06 mM nitrous acid in the soil solution at 4 weeks. When an LSM was added (40% [wt/wt] soil moisture) to an alkaline soil (pH 7.9) where VFAs are not toxic, microsclerotia germination was reduced by 80% after 1 week. Here the pH increased to 8.9 and the concentration of ammonia reached 30 mM in the soil solution. An ammonium chloride solution having an equivalent concentration of ammonium as the manure was shown to have the same spectrum of toxicity as the manure in assays ranging from pH 7 to 9, both in solutions and above the solutions. At pH 9, the concentration of ammonia reached 18 mM and 100% mortality of microsclerotia occurred. Thus, in acid soils, LSM can kill microsclerotia of V. dahliae by VFA and/or nitrous acid toxicity and in alkaline

  13. Purification of amide alkaloids from Piper longum L. using preparative two-dimensional normal-phase liquid chromatography × reversed-phase liquid chromatography.

    Science.gov (United States)

    Li, Kuiyong; Zhu, Wenya; Fu, Qing; Ke, Yanxiong; Jin, Yu; Liang, Xinmiao

    2013-06-07

    A comprehensive off-line two-dimensional liquid chromatography (2D-LC) method coupling normal phase liquid chromatography (NPLC) and reversed phase liquid chromatography (RPLC) was developed for separation and purification of amide alkaloids from Piper longum L. In the first dimension, the crude alkaloid fractions were separated in NPLC mode and 20 fractions were collected. Then fractions 5-20 were selected for further purification in RPLC mode in the second dimension. The purities of RPLC fractions with similar structures were all identified accurately by ultra performance liquid chromatography (UPLC). In total, 28 compounds with high purity were obtained and their structures were comprehensively characterized by electrospray ionization-mass spectrometry (ESI-MS) and nuclear magnetic resonance (NMR) spectroscopy. The results demonstrate that this 2D NPLC × RPLC method with good orthogonality (58.3%) was effective for the preparative separation and purification of amide alkaloids from Piper longum L.

  14. Chiral Separation of Naproxen with Immobilized Liquid Phases

    NARCIS (Netherlands)

    Corderi Gandara, Sandra; Vitasari, C.R.; Gramblicka, M.; Giard, T.; Schuur, Boelo

    2016-01-01

    The use of solvent-impregnated resins (SIRs) as a hybrid technology between liquid extraction and adsorption was investigated for the enantioseparation of naproxen. A chiral recognition system from the enantioselective liquid–liquid extraction from the literature was taken as a starting point, compr

  15. Ultrapreconcentration and determination of organophosphorus pesticides in water by solid-phase extraction combined with dispersive liquid-liquid microextraction and high-performance liquid chromatography.

    Science.gov (United States)

    Chen, Junhua; Zhou, Guangming; Deng, Yongli; Cheng, Hongmei; Shen, Jie; Gao, Yi; Peng, Guilong

    2016-01-01

    Solid-phase extraction coupled with dispersive liquid-liquid microextraction was developed as an ultra-preconcentration method for the determination of four organophosphorus pesticides (isocarbophos, parathion-methyl, triazophos and fenitrothion) in water samples. The analytes considered in this study were rapidly extracted and concentrated from large volumes of aqueous solutions (100 mL) by solid-phase extraction coupled with dispersive liquid-liquid microextraction and then analyzed using high performance liquid chromatography. Experimental variables including type and volume of elution solvent, volume and flow rate of sample solution, salt concentration, type and volume of extraction solvent and sample solution pH were investigated for the solid-phase extraction coupled with dispersive liquid-liquid microextraction with these analytes, and the best results were obtained using methanol as eluent and ethylene chloride as extraction solvent. Under the optimal conditions, an exhaustive extraction for four analytes (recoveries >86.9%) and high enrichment factors were attained. The limits of detection were between 0.021 and 0.15 μg/L. The relative standard deviations for 0.5 μg/L of the pesticides in water were in the range of 1.9-6.8% (n = 5). The proposed strategy offered the advantages of simple operation, high enrichment factor and sensitivity and was successfully applied to the determination of four organophosphorus pesticides in water samples.

  16. Dissolved organic carbon enhances the mass transfer of hydrophobic organic compounds from Nonaqueous Phase Liquids (NAPLs) into the aqueous phase

    NARCIS (Netherlands)

    Smith, K.E.C.; Thullner, M.; Wick, L.Y.; Harms, H.

    2011-01-01

    The hypothesis that dissolved organic carbon (DOC) enhances the mass transfer of hydrophobic organic compounds from nonaqueous phase liquids (NAPLs) into the aqueous phase above that attributable to dissolved molecular diffusion alone was tested. In controlled experiments, mass transfer rates of

  17. Experimental analysis on adjusting performance of vapor-liquid two-phase flow controller

    Institute of Scientific and Technical Information of China (English)

    LI Hui-jun; TU Shan

    2006-01-01

    The vapor-liquid self-adjusting controller is an innovative automatic regulating valve. In order to ensure adjusted objects run safely and economically, the controller automatically adjusts the liquid flux to keep liquid level at a required level according to physical properties of vapor-liquid two-phase fluid. The adjusting mechanics, the controller' s performance and influencing factors of its stability have been analyzed in this paper. The theoretical analysis and successful applications have demonstrated this controller can keep the liquid level steady with good performance. The actual application in industry has shown that the controller can satisfactorily meet the requirement of industrial production and has wide application areas.

  18. Phase equilibria in ionic liquid-aromatic compound mixtures, including benzene fluorination effects.

    Science.gov (United States)

    Blesic, Marijana; Lopes, José N Canongia; Pádua, Agílio A H; Shimizu, Karina; Gomes, Margarida F Costa; Rebelo, Luís Paulo N

    2009-05-28

    This work extends the scope of previous studies on the phase behavior of mixtures of ionic liquids with benzenes or its derivatives by determining the solid-liquid and liquid-liquid phase diagrams of mixtures containing an ionic liquid and a fluorinated benzene. The systems studied include 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide plus hexafluorobenzene or 1,3,5-trifluorobenzene and 1-ethyl-3-methylimidazolium triflate or N-ethyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide plus benzene. The phase diagrams exhibit different kinds of solid-liquid behavior: the (usual) occurrence of eutectic points; the (not-so-usual) presence of congruent melting points and the corresponding formation of inclusion crystals; or the observation of different ionic liquid crystalline phases (polymorphism). These different types of behavior can be controlled by temperature annealing during crystallization or by the nature of the aromatic compound and can be interpreted, at a molecular level, taking into account the structure of the crystals or liquid mixtures, together with the unique characteristics of ionic liquids, namely the dual nature of their interactions with aromatic compounds.

  19. Alteration of gas phase ion polarizabilities upon hydration in high dielectric liquids.

    Science.gov (United States)

    Buyukdagli, Sahin; Ala-Nissila, T

    2013-07-28

    We investigate the modification of gas phase ion polarizabilities upon solvation in polar solvents and ionic liquids. To this aim, we develop a classical electrostatic theory of charged liquids composed of solvent molecules modeled as finite size dipoles, and embedding polarizable ions that consist of Drude oscillators. In qualitative agreement with ab initio calculations of polar solvents and ionic liquids, the hydration energy of a polarizable ion in both types of dielectric liquid is shown to favor the expansion of its electronic cloud. Namely, the ion carrying no dipole moment in the gas phase acquires a dipole moment in the liquid environment, but its electron cloud also reaches an enhanced rigidity. We find that the overall effect is an increase of the gas phase polarizability upon hydration. In the specific case of ionic liquids, it is shown that this hydration process is driven by a collective solvation mechanism where the dipole moment of a polarizable ion induced by its interaction with surrounding ions self-consistently adds to the polarization of the liquid, thereby amplifying the dielectric permittivity of the medium in a substantial way. We propose this self-consistent hydration as the underlying mechanism behind the high dielectric permittivities of ionic liquids composed of small charges with negligible gas phase dipole moment. Hydration being a correlation effect, the emerging picture indicates that electrostatic correlations cannot be neglected in polarizable liquids.

  20. Liquid phase sintering, II: Computer study of skeletal settling and solid phase extrication in a microgravity environment

    Directory of Open Access Journals (Sweden)

    Nikolić Z.S.

    2008-01-01

    Full Text Available A two-dimensional numerical method based on the Brownian motion model and on the Densification model for simulation of liquid phase sintering in microgravity environment will be developed. Both models will be based on domain topology (two-dimensional particle representation and control volume methodology and on three submodels for domain translation, solid skeleton formation and domain extrication. This method will be tested in order to conduct a study of diffusion phenomena and microgravitational effects on microstructural evolution influenced by skeletal settling combined with solid-phase extrication during liquid phase sintering of porous W-Ni system.

  1. Development and validation of a portable gas phase standard generation and calibration system for volatile organic compounds

    Directory of Open Access Journals (Sweden)

    P. Veres

    2010-06-01

    Full Text Available We report on the development of an accurate, portable, dynamic calibration system for volatile organic compounds (VOCs. The Mobile Organic Carbon Calibration System (MOCCS combines the production of gas-phase VOC standards using permeation or diffusion sources with quantitative total organic carbon (TOC conversion on a palladium surface to CO2 in the presence of oxygen, and the subsequent CO2 measurement. MOCCS was validated using three different comparisons: (1 TOC of high accuracy methane standards compared well to expected concentrations (3% relative error, (2 a gas-phase benzene standard was generated using a permeation source and measured by TOC and gas chromatography mass spectrometry (GC-MS with excellent agreement (<4% relative difference, and (3 total carbon measurement of 4 known gas phase mixtures were performed and compared to a calculated carbon content to agreement within the stated uncertainties of the standards. Measurements from laboratory biomass burning experiments of formic acid by negative-ion proton-transfer chemical-ionization mass spectrometry (NI-PT-CIMS and formaldehyde by proton transfer reaction-mass spectrometry (PTR-MS, both calibrated using MOCCS, were compared to open path Fourier transform infrared spectroscopy (OP-FTIR to validate the MOCCS calibration and were found to compare well (R2 of 0.91 and 0.99, respectively.

  2. Development and validation of a portable gas phase standard generation and calibration system for volatile organic compounds

    Directory of Open Access Journals (Sweden)

    P. Veres

    2010-01-01

    Full Text Available We report on the development of an accurate, portable, dynamic calibration system for volatile organic compounds (VOCs. The Mobile Organic Carbon Calibration System (MOCCS combines the production of gas-phase VOC standards using permeation or diffusion sources with quantitative total organic carbon (TOC conversion on a palladium surface to CO2 in the presence of oxygen, and the subsequent CO2 measurement. MOCCS was validated using three different comparisons: (1 TOC of high accuracy methane standards compared well to expected concentrations (3% relative error, (2 a gas-phase benzene standard was generated using a permeation source and measured by TOC and gas chromatography mass spectrometry (GC-MS with excellent agreement (<4% relative difference, and (3 total carbon measurement of 4 known gas phase mixtures were performed and compared to a calculated carbon content to agreement within the stated uncertainties of the standards. Measurements from laboratory biomass burning experiments of formic acid by negative-ion proton-transfer chemical-ionization mass spectrometry (NI-PT-CIMS and formaldehyde by proton transfer reaction-mass spectrometry (PTR-MS, both calibrated using MOCCS, were compared to open path Fourier transform infrared spectroscopy (OP-FTIR to validate the MOCCS calibration and were found to compare well (R2 of 0.91 and 0.99 respectively.

  3. Dielectric spectroscopy of isotropic liquids and liquid crystal phases with dispersed graphene oxide

    Science.gov (United States)

    Al-Zangana, Shakhawan; Iliut, Maria; Boran, Gökçen; Turner, Michael; Vijayaraghavan, Aravind; Dierking, Ingo

    2016-08-01

    Graphene oxide (GO) flakes of different sizes were prepared and dispersed in isotropic and nematic (anisotropic) fluid media. The dielectric relaxation behaviour of GO-dispersions was examined for a wide temperature (25-60 oC) and frequency range (100 Hz-2 MHz). The mixtures containing GO flakes exhibited varying dielectric relaxation processes, depending on the size of the flakes and the elastic properties of the dispersant fluid. Relaxation frequencies of the GO doped isotropic media, such as isopropanol IPA, were observed to be much lower than the GO doped thermotropic nematic medium 5CB. It is anticipated that the slow relaxation frequencies (~10 kHz) could be resulting from the relaxation modes of the GO flakes while the fast relaxation frequencies (~100 kHz) could indicate strongly slowed down molecular modes of the nematogenic molecules, which are anchored to the GO flakes via dispersion interactions. The relaxation frequencies decreased as the size of the GO flakes in the isotropic solvent was increased. Polarizing microscopy showed that GO flakes with a mean diameter of 10 μm, dispersed in water, formed a lyotropic nematic liquid crystal phase. This lyotropic nematic exhibited the slowest dielectric relaxation process, with relaxation frequencies in the order of 2 kHz, as compared to the GO-isotropic suspension and the GO-doped 5CB.

  4. Phase equilibria and modeling of pyridinium-based ionic liquid solutions.

    Science.gov (United States)

    Domańska, Urszula; Królikowski, Marek; Ramjugernath, Deresh; Letcher, Trevor M; Tumba, Kaniki

    2010-11-25

    The phase diagrams of the ionic liquid (IL) N-butyl-4-methylpyridinium bis{(trifluoromethyl)sulfonyl}imide ([BM(4)Py][NTf(2)]) with water, an alcohol (1-butanol, 1-hexanol, 1-octanol, 1-decanol), an aromatic hydrocarbon (benzene, toluene, ethylbenzene, n-propylbenzene), an alkane (n-hexane, n-heptane, n-octane), or cyclohexane have been measured at atmospheric pressure using a dynamic method. This work includes the characterization of the synthesized compound by water content and also by differential scanning calorimetry. Phase diagrams for the binary systems of [BM(4)Py][NTf(2)] with all solvents reveal eutectic systems with regards to (solid-liquid) phase equilibria and show immiscibility in the liquid phase region with an upper critical solution temperature (UCST) in most of the mixtures. The phase equilibria (solid, or liquid-liquid) for the binary systems containing aliphatic hydrocarbons reported here exhibit the lowest solubility and the highest immiscibility gap, a trend which has been observed for all ILs. The reduction of experimental data has been carried out using the nonrandom two-liquid (NRTL) correlation equation. The phase diagrams reported here have been compared with analogous phase diagrams reported previously for systems containing the IL N-butyl-4-methylpyridinium tosylate and other pyridinium-based ILs. The influence of the anion of the IL on the phase behavior has been discussed.

  5. Research of Characteristics of Gas-liquid Two-phase Pressure Drop in Microreactor

    OpenAIRE

    Li Dan

    2015-01-01

    With the research system of nitrogen and deionized water, this paper researches the pressure drop of gas-liquid two-phase flow in the circular microchannel with an inner diameter which is respectively 0.9mm and 0.5mm, analyzes the effect of microchannel diameter on gas-liquid two-phase frictional pressure drop in the microchannel reactor, and compares with the result of frictional pressure drop and the predicting result of divided-phase flow pattern. The result shows that, the gas-liquid two-...

  6. Liquefaction and methanization of solid and liquid coffee wastes by two phase anaerobic digestion process.

    Science.gov (United States)

    Houbron, E; Larrinaga, A; Rustrian, E

    2003-01-01

    This study attempted to investigate the feasibility of volatile fatty acid (VFA) production from coffee pulp hydrolyse, and further to determine the potential of methanization of both the pre-acidified effluent and the coffee wastewater. The experiments were carried out in 2 completely mixed reactors, each one with a working volume of 4 litres. Coffee pulp was used as substrate in the acidogenic reactor and different mixtures of pulper and wash-water and pre-acidified effluent in the methanogenic one. The acidogenic and methanogenic reactors were operated at an organic loading rate of 5 COD g x l(-1) x d(-1) and 0.5 COD g x l(-1) x d(-1). The total, soluble and VFA's effluent COD concentrations of the acidogenic reactor present average values of 57.75, 17.00 and 13.92 g x l(-1) respectively. Under these experimental conditions, 23% (COD based) of coffee pulp was hydrolysed with a rate of 1.32 gCOD x l(-1) x d(-1) and the soluble fraction was transformed to VFA's with an acidification efficiency of 82%. Total VFA's concentration reached a value of 13.9 gCOD x l(-1), and acetate, propionate, butyrate and valerate represented 52%, 28%, 9% and 11% respectively of the liquid phase COD. In the methanogenic reactor, COD removal and methanization of fresh coffee wastewater, pre-acidified effluent and both combined occur with an efficiency of 85% to 95% respectively, with a characteristic biogas composition of 80% CH4 and 20% CO2. These results show that a humid coffee "Beneficio" processing daily 23 tons of cherry coffee (fresh fruit), equipped with a two stage anaerobic digestion process could generate at least 1,886 CH4 m3 x d(-1). This represents an increase in methane production by a factor 3 to 5 compared to a "Beneficio" using anaerobic digestion only for the treatment of its wastewater.

  7. The rate of photocatalytic oxidation of aromatic volatile organic compounds in the gas-phase

    Science.gov (United States)

    Boulamanti, Aikaterini K.; Korologos, Christos A.; Philippopoulos, Constantine J.

    In the present study, the gas-solid heterogeneous photocatalytic oxidation (PCO) of six aromatic species of volatile organic compounds (VOCs), benzene, toluene, ethylbenzene, m-, o- and p-xylene over illuminated titania was carried out at ambient temperature in a continuous stirring-tank reactor. Initial VOC concentrations were in the low parts per million (ppm) range. Maximum conversions were over 90% for all compounds except from benzene, ethylbenzene and o-xylene, while the residence time varied from 50 to 210 s. Intermediates were detected only in the case of the xylenes, but catalyst deactivation occurred for all six compounds. The PCO kinetics were well fit by a Langmuir-Hinshelwood (L-H) model for monomolecular surface reaction and it was proved that the reaction rate is related to both constants. The rate constants ranged from 0.147 ppm s -1 g cat-1 for benzene to 1.067 ppm s -1 g cat-1 for m-xylene, while the adsorption constants from 0.424 ppm -1 for ethylbenzene to 0.69 ppm -1 for toluene. The molecular structure of the compounds was found to play an important role in the reaction. Finally the efficiency of the procedure in the case of a mixture of these aromatic substances was tested.

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

    Energy Technology Data Exchange (ETDEWEB)

    Dumont, Philip John [Iowa State Univ., Ames, IA (United States)

    1996-04-23

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

  9. GC/MS analysis of volatiles obtained by headspace solid-phase microextraction and simultaneous-distillation extraction from Rabdosia serra (MAXIM.) HARA leaf and stem.

    Science.gov (United States)

    Lin, Lianzhu; Zhuang, Mingzhu; Lei, Fenfen; Yang, Bao; Zhao, Mouming

    2013-01-15

    Volatiles in Rabdosia serra were investigated by headspace solid phase microextraction (HS-SPME) and simultaneous-distillation extraction (SDE). The HS-SPME technique was previously evaluated to optimise sampling conditions. A total of 56 and 48 compounds including alcohols, aldehydes, hydrocarbons, ketones, carboxylic acid, ester, and aromatics were identified in leaf and stem by optimised HS-SPME method (CAR/PDMS fibre; incubation time, 10 min; extraction temperature, 50°C; extraction time, 40 min), respectively. 1-Octen-3-ol and (2E)-hexenal had significant contribution to R. serra aroma. Cluster analysis indicated that leaf and stem exhibited different volatile diversity. Air drying was favourable for the retention of the volatiles, while freeze- and sun-drying led to the loss of volatiles. SDE method preferred to the analysis of compounds with low volatility including fatty acids and esters. HS-SPME was a useful technique for the analysis of readily volatile components for the characteristics of R. serra aroma.

  10. Phase coexistence properties of liquid mercury: a simulation study

    Institute of Scientific and Technical Information of China (English)

    Jean-Louis Bretonnet; Jean-Marc Bomont

    2006-01-01

    The thermophysical properties of expanded liquid mercury have been investigated along the liquid-vapor coexis tence curve by using Monte Carlo and Molecular Dynamic simulations. For the purpose, an empirical state dependent interatomic potential for the region of dense metallic liquid is used, while the state dependence is not necessary near the critical point. In order to test the validity of this potential, we determine the surface layering and the sound velocity, two properties very sensitive to the choice of the potential. Our results are in quite good agreement with other theoretical results and to the experimental data available in the literature.

  11. Liquid and vapour-phase antifungal activities of selected essential oils against candida albicans: microscopic observations and chemical characterization of cymbopogon citratus

    Directory of Open Access Journals (Sweden)

    Malik Anushree

    2010-11-01

    Full Text Available Abstract Background Use of essential oils for controlling Candida albicans growth has gained significance due to the resistance acquired by pathogens towards a number of widely-used drugs. The aim of this study was to test the antifungal activity of selected essential oils against Candida albicans in liquid and vapour phase and to determine the chemical composition and mechanism of action of most potent essential oil. Methods Minimum Inhibitory concentration (MIC of different essential oils in liquid phase, assayed through agar plate dilution, broth dilution & 96-well micro plate dilution method and vapour phase activity evaluated through disc volatilization method. Reduction of C. albicans cells with vapour exposure was estimated by kill time assay. Morphological alteration in treated/untreated C. albicans cells was observed by the Scanning electron microscopy (SEM/Atomic force microscopy (AFM and chemical analysis of the strongest antifungal agent/essential oil has been done by GC, GC-MS. Results Lemon grass (Cymbopogon citratus essential oil exhibited the strongest antifungal effect followed by mentha (Mentha piperita and eucalyptus (Eucalyptus globulus essential oil. The MIC of lemon grass essential oil in liquid phase (288 mg/l was significantly higher than that in the vapour phase (32.7 mg/l and a 4 h exposure was sufficient to cause 100% loss in viability of C. albicans cells. SEM/AFM of C. albicans cells treated with lemon grass essential oil at MIC level in liquid and vapour phase showed prominent shrinkage and partial degradation, respectively, confirming higher efficacy of vapour phase. GC-MS analysis revealed that lemon grass essential oil was dominated by oxygenated monoterpenes (78.2%; α-citral or geranial (36.2% and β-citral or neral (26.5%, monoterpene hydrocarbons (7.9% and sesquiterpene hydrocarbons (3.8%. Conclusion Lemon grass essential oil is highly effective in vapour phase against C. albicans, leading to deleterious

  12. Liquid and vapour-phase antifungal activities of selected essential oils against Candida albicans: microscopic observations and chemical characterization of Cymbopogon citratus.

    Science.gov (United States)

    Tyagi, Amit K; Malik, Anushree

    2010-11-10

    Use of essential oils for controlling Candida albicans growth has gained significance due to the resistance acquired by pathogens towards a number of widely-used drugs. The aim of this study was to test the antifungal activity of selected essential oils against Candida albicans in liquid and vapour phase and to determine the chemical composition and mechanism of action of most potent essential oil. Minimum Inhibitory concentration (MIC) of different essential oils in liquid phase, assayed through agar plate dilution, broth dilution & 96-well micro plate dilution method and vapour phase activity evaluated through disc volatilization method. Reduction of C. albicans cells with vapour exposure was estimated by kill time assay. Morphological alteration in treated/untreated C. albicans cells was observed by the Scanning electron microscopy (SEM)/Atomic force microscopy (AFM) and chemical analysis of the strongest antifungal agent/essential oil has been done by GC, GC-MS. Lemon grass (Cymbopogon citratus) essential oil exhibited the strongest antifungal effect followed by mentha (Mentha piperita) and eucalyptus (Eucalyptus globulus) essential oil. The MIC of lemon grass essential oil in liquid phase (288 mg/l) was significantly higher than that in the vapour phase (32.7 mg/l) and a 4 h exposure was sufficient to cause 100% loss in viability of C. albicans cells. SEM/AFM of C. albicans cells treated with lemon grass essential oil at MIC level in liquid and vapour phase showed prominent shrinkage and partial degradation, respectively, confirming higher efficacy of vapour phase. GC-MS analysis revealed that lemon grass essential oil was dominated by oxygenated monoterpenes (78.2%); α-citral or geranial (36.2%) and β-citral or neral (26.5%), monoterpene hydrocarbons (7.9%) and sesquiterpene hydrocarbons (3.8%). Lemon grass essential oil is highly effective in vapour phase against C. albicans, leading to deleterious morphological changes in cellular structures and cell

  13. Evaluation of volatile metabolites as markers in Lycopersicon esculentum L. cultivars discrimination by multivariate analysis of headspace solid phase microextraction and mass spectrometry data.

    Science.gov (United States)

    Figueira, José; Câmara, Hugo; Pereira, Jorge; Câmara, José S

    2014-02-15

    To gain insights on the effects of cultivar on the volatile metabolomic expression of different tomato (Lycopersicon esculentum L.) cultivars--Plum, Campari, Grape, Cherry and Regional, cultivated under similar edafoclimatic conditions, and to identify the most discriminate volatile marker metabolites related to the cultivar, the chromatographic profiles resulting from headspace solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-qMS) analysis, combined with multivariate analysis were investigated. The data set composed by the 77 volatile metabolites identified in the target tomato cultivars, 5 of which (2,2,6-trimethylcyclohexanone, 2-methyl-6-methyleneoctan-2-ol, 4-octadecyl-morpholine, (Z)-methyl-3-hexenoate and 3-octanone) are reported for the first time in tomato volatile metabolomic composition, was evaluated by chemometrics. Firstly, principal component analysis was carried out in order to visualise data trends and clusters, and then, linear discriminant analysis in order to detect the set of volatile metabolites able to differentiate groups according to tomato cultivars. The results obtained revealed a perfect discrimination between the different Lycopersicon esculentum L. cultivars considered. The assignment success rate was 100% in classification and 80% in prediction ability by using "leave-one-out" cross-validation procedure. The volatile profile was able to differentiate all five cultivars and revealed complex interactions between them including the participation in the same biosynthetic pathway. The volatile metabolomic platform for tomato samples obtained by HS-SPME/GC-qMS here described, and the interrelationship detected among the volatile metabolites can be used as a roadmap for biotechnological applications, namely to improve tomato aroma and their acceptance in the final consumer, and for traceability studies. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. The phase diagram of molybdenum at extreme conditions and the role of local liquid structures

    Energy Technology Data Exchange (ETDEWEB)

    Ross, M

    2008-08-15

    Recent DAC measurements made of the Mo melting curve by the x-ray diffraction studies confirms that, up to at least 110 GPa (3300K) melting is directly from bcc to liquid, evidence that there is no basis for a speculated bcc-hcp or fcc transition. An examination of the Poisson Ratio, obtained from shock sound speed measurements, provides evidence that the 210 GPa (4100K) transition detected from shock experiments is a continuation of the bcc-liquid melting, but is from a bcc-to a solid-like mixed phase rather than to liquid. Calculations, modeled to include the free energy of liquid local structures, predict that the transition from the liquid to the mixed phase is near 150 GPa(3500K). The presence of local structures provides the simplest and most direct explanation for the Mo phase diagram, and the low melting slopes.

  15. Explicit modeling of volatile organic compounds partitioning in the atmospheric aqueous phase

    Directory of Open Access Journals (Sweden)

    C. Mouchel-Vallon

    2012-09-01

    Full Text Available The gas phase oxidation of organic species is a multigenerational process involving a large number of secondary compounds. Most secondary organic species are water-soluble multifunctional oxygenated molecules. The fully explicit chemical mechanism GECKO-A (Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere is used to describe the oxidation of organics in the gas phase and their mass transfer to the aqueous phase. The oxidation of three hydrocarbons of atmospheric interest (isoprene, octane and α-pinene is investigated for various NOx conditions. The simulated oxidative trajectories are examined in a new two dimensional space defined by the mean oxidation state and the solubility. The amount of dissolved organic matter was found to be very low (<2% under a water content typical of deliquescent aerosols. For cloud water content, 50% (isoprene oxidation to 70% (octane oxidation of the carbon atoms are found in the aqueous phase after the removal of the parent hydrocarbons for low NOx conditions. For high NOx conditions, this ratio is only 5% in the isoprene oxidation case, but remains large for α-pinene and octane oxidation cases (40% and 60%, respectively. Although the model does not yet include chemical reactions in the aqueous phase, much of this dissolved organic matter should be processed in cloud drops and modify both oxidation rates and the speciation of organic species.

  16. Semi-volatile organic compounds in the particulate phase in dwellings: A nationwide survey in France

    Science.gov (United States)

    Mandin, Corinne; Mercier, Fabien; Ramalho, Olivier; Lucas, Jean-Paul; Gilles, Erwann; Blanchard, Olivier; Bonvallot, Nathalie; Glorennec, Philippe; Le Bot, Barbara

    2016-07-01

    Sixty-six semi-volatile organic compounds (SVOCs)-phthalates, polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), one pyrethroid, organochlorine and organophosphorous pesticides, alkylphenols, synthetic musks, tri-n-butylphosphate and triclosan-were measured on PM10 filters collected over 7 days during a nationwide survey of 285 French dwellings, representative of nearly 25 million housing units. Thirty-five compounds were detected in more than half of the dwellings. PAHs, phthalates and triclosan were the major particle-bound SVOCs, with a median concentration greater than 1 ng m-3 for butylbenzyl phthalate (BBP) (median: 1.6 ng m-3), di(2-ethylhexyl) phthalate (DEHP) (46 ng m-3) and di-iso-nonyl phthalate (DiNP) (7.9 ng m-3), and greater than 0.1 ng m-3 for triclosan (114 pg m-3), benzo(a)pyrene (138 pg m-3), benzo(b)fluoranthene (306 pg m-3), benzo(g,h,i)perylene (229 pg m-3), and indeno(1,2,3-c,d)pyrene (178 pg m-3). For most of the SVOCs, higher concentrations were found in the dwellings of smokers and during the heating season. The concentrations of banned SVOCs-namely, PCBs and organochlorine pesticides-were correlated. Permethrin, 4-tert-butylphenol and bisphenol-A showed no correlation with the other SVOCs and seemed to have their own specific sources. Most SVOCs were positively associated with PM10 concentration, suggesting that any factor that raises the mass of indoor airborne particles also increases the exposure to SVOCs through inhalation.

  17. Development and validation of a reversed phase liquid chromatographic method for analysis of oxytetracycline and related impurities.

    Science.gov (United States)

    Kahsay, Getu; Shraim, Fairouz; Villatte, Philippe; Rotger, Jacques; Cassus-Coussère, Céline; Van Schepdael, Ann; Hoogmartens, Jos; Adams, Erwin

    2013-03-05

    A simple, robust and fast high-performance liquid chromatographic method is described for the analysis of oxytetracycline and its related impurities. The principal peak and impurities are all baseline separated in 20 min using an Inertsil C₈ (150 mm × 4.6 mm, 5 μm) column kept at 50 °C. The mobile phase consists of a gradient mixture of mobile phases A (0.05% trifluoroacetic acid in water) and B (acetonitrile-methanol-tetrahydrofuran, 80:15:5, v/v/v) pumped at a flow rate of 1.3 ml/min. UV detection was performed at 254 nm. The developed method was validated for its robustness, sensitivity, precision and linearity in the range from limit of quantification (LOQ) to 120%. The limits of detection (LOD) and LOQ were found to be 0.08 μg/ml and 0.32 μg/ml, respectively. This method allows the separation of oxytetracycline from all known and 5 unknown impurities, which is better than previously reported in the literature. Moreover, the simple mobile phase composition devoid of non-volatile buffers made the method suitable to interface with mass spectrometry for further characterization of unknown impurities. The developed method has been applied for determination of related substances in oxytetracycline bulk samples available from four manufacturers. The validation results demonstrate that the method is reliable for quantification of oxytetracycline and its impurities.

  18. Vapor-liquid (VLE) and liquid-liquid (LLE) phase equilibria calculations for polystyrene plus methyleyclohexane and polystyrene plus cyclohexane solutions

    DEFF Research Database (Denmark)

    Wilczura-Wachnik, H.; Jonsdottir, Svava Osk

    2006-01-01

    This paper presents the vapor-liquid (VLE) and liquid-liquid (LLE) phase equilibria predictions for polystyrene in two theta solvents: cyclohexane and methylcyclohexane. VLE calculations were performed with the Elbro free volume method and a modified version of the PC-SAFT method, as well...... as with three UNIFAC type group contribution models: Entropic Free Volume + UNIFAC VLE 1 coeff., Entropic Free Volume + UNIFAC VLE 2coeff., and Oishi-Prausnitz + UNIFAC VLE 2coeff. Solvent activities were calculated for the polystyrene + cyclohexane and polystyrene + methylcyclohcxane solutions, and compared...

  19. MORPHOLOGICAL AND KINETIC STUDIES OF PHASE TRANSITIONS OF A SIDE-CHAIN LIQUID CRYSTALLINE POLYMER

    Institute of Scientific and Technical Information of China (English)

    Chi-bing Tan; Shu-fan Zhang; Mao Xu

    1999-01-01

    The morphological changes of a side-chain liquid-crystalline polymethacrylate during isotropization and liquid-crystallization transitions were studied by means of polarizing microscopy. These transitions were found to be composed of the initiation of a new phase at local places of the old phase matrix and the growth of the new phase domains. The kinetics of the liquid-crystallization of the polymer from an isotropic melt to a smectic mesophase was also investigated. The isothermal process of the transition can be described by the Avrami equation. The values of the Avrami exponent were found to be around 2.6. which is lower than the value usually obtained for crystallization transition of polymers, but larger than that reported for liquid-crystallization transition of main-chain polymers. These results may indicate the difference in growth geometry of new phase during transition between crystallization and liquid-crystallization in general and between liquid-crystallization of main-chain and side-chain polymers. It was found that the liquidcrystallization of the used side-chain polymethacrylate may occur at small undercoolings with high transformation rate similar to that of main-chain polymers and small-molecule liquid crystals, while the crystallization of polymers can only proceed at large undercoolings. These phenomena can be explained by the idea that the surface free energy of nucleus during liquid-crystallization transition is less than that for crystallization, and evidence was obtained from analysis of the temperature dependence of the transformation rate.

  20. Gallium-rich Pd-Ga phases as supported liquid metal catalysts

    Science.gov (United States)

    Taccardi, N.; Grabau, M.; Debuschewitz, J.; Distaso, M.; Brandl, M.; Hock, R.; Maier, F.; Papp, C.; Erhard, J.; Neiss, C.; Peukert, W.; Görling, A.; Steinrück, H.-P.; Wasserscheid, P.

    2017-09-01

    A strategy to develop improved catalysts is to create systems that merge the advantages of heterogeneous and molecular catalysis. One such system involves supported liquid-phase catalysts, which feature a molecularly defined, catalytically active liquid film/droplet layer adsorbed on a porous solid support. In the past decade, this concept has also been extended to supported ionic liquid-phase catalysts. Here we develop this idea further and describe supported catalytically active liquid metal solutions (SCALMS). We report a liquid mixture of gallium and palladium deposited on porous glass that forms an active catalyst for alkane dehydrogenation that is resistant to coke formation and is thus highly stable. X-ray diffraction and X-ray photoelectron spectroscopy, supported by theoretical calculations, confirm the liquid state of the catalytic phase under the reaction conditions. Unlike traditional heterogeneous catalysts, the supported liquid metal reported here is highly dynamic and catalysis does not proceed at the surface of the metal nanoparticles, but presumably at homogeneously distributed metal atoms at the surface of a liquid metallic phase.

  1. Gas-to-liquids process using multi-phase flow, non-thermal plasma microreactor

    NARCIS (Netherlands)

    Agiral, Anil; Nozaki, Tomohiro; Nakase, Masahiko; Yuzawa, Shuhei; Okazaki, Ken; Gardeniers, J.G.E. (Han)

    2011-01-01

    A multi-phase flow non-thermal plasma microreactor based on dielectric barrier discharge has been developed for partial oxidation of methane to liquid oxygenates at atmospheric pressure. A pulsed water injection method has been used to remove condensable liquid components from the active discharge r

  2. Investigating the Retention Mechanisms of Liquid Chromatography Using Solid-Phase Extraction Cartridges

    Science.gov (United States)

    O'Donnell, Mary E.; Musial, Beata A.; Bretz, Stacey Lowery; Danielson, Neil D.; Ca, Diep

    2009-01-01

    Liquid chromatography (LC) experiments for the undergraduate analytical laboratory course often illustrate the application of reversed-phase LC to solve a separation problem, but rarely compare LC retention mechanisms. In addition, a high-performance liquid chromatography instrument may be beyond what some small colleges can purchase. Solid-phase…

  3. On the implications of aerosol liquid water and phase separation for organic aerosol mass

    Data.gov (United States)

    U.S. Environmental Protection Agency — This dataset contains data presented in the figures of the paper "On the implications of aerosol liquid water and phase separation for organic aerosol mass"...

  4. Light-Weight, Low-Cost, Single-Phase, Liquid-Cooled Cold Plate (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Narumanchi, S.

    2013-07-01

    This presentation, 'Light-Weight, Low-Cost, Single-Phase Liquid-Cooled Cold Plate,' directly addresses program goals of increased power density, specific power, and lower cost of power electronics components through improved thermal management.

  5. Definition of Astrobiology with Liquid Phase Change and Dynamic Cyclic Change

    Science.gov (United States)

    Miura, Yas.

    2010-04-01

    Definition of astrobiology is required for three factors of combined inorganic and organic materials of fossils, dynamic changes of gas-liquid-solid phases as min-water Earth with cycle, and space and time factors also in deep space.

  6. Kinetic aspects of hollow fiber liquid-phase microextraction and electromembrane extraction

    DEFF Research Database (Denmark)

    Gjelstad, Astrid; Jensen, Henrik; Rasmussen, Knut Einar

    2012-01-01

    In this paper, extraction kinetics was investigated experimentally and theoretically in hollow fiber liquid-phase microextraction (HF-LPME) and electromembrane extraction (EME) with the basic drugs droperidol, haloperidol, nortriptyline, clomipramine, and clemastine as model analytes. In HF...

  7. Experimental design applied to the analysis of volatile compounds in apple juice by headspace solid-phase microextraction.

    Science.gov (United States)

    Llorente, Daniel Díaz; Abrodo, Pilar Arias; de la Fuente, Enrique Dapena; Alvarez, Jaime González; Alvarez, Maria Dolores Gutiérrez; Gomis, Domingo Blanco

    2011-06-01

    A simple and fast method based on solid-phase microextraction (SPME) followed by fast gas chromatography (Fast GC) has been developed for the analysis of volatile compounds in Asturian apple juices employed in the cider production. Three different fiber coatings have been checked (PDMS, PDMS-DVB and CAR-PDMS) and PDMS-DVB has been presented to be the most suitable one. Experimental design has been employed in the optimization of extraction factors and robustness assessment. The use of Fast GC allowed the separation of 14 compounds (esters, aldehydes and alcohols) in approximately 4 min, clearly reducing the analysis time when compared to conventional GC. Good linearity, recoveries and repeatability of the solid-phase microextraction were obtained with r(2) values, recoveries and relative standard deviations ranging from 0.9822 to 0.9998, 83.2 to 109.8% and 0.5 to 11.7%, respectively, using standard solution. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Utilization of micellar electrokinetic chromatography-tandem mass spectrometry employed volatile micellar phase in the analysis of cathinone designer drugs.

    Science.gov (United States)

    Švidrnoch, Martin; Lněníčková, Ludmila; Válka, Ivo; Ondra, Peter; Maier, Vítězslav

    2014-08-22

    A micellar electrokinetic chromatography method with tandem mass spectrometry has been developed for the selective separation, identification and determination of twelve new designer drugs from the group of synthetic cathinones. Ammonium salt of perfluorooctanoic acid at various concentrations as a volatile background electrolyte (BGE) to create micellar phase was studied for separation of selected synthetic cathinones with direct tandem mass spectrometry without significant loss of detection sensitivity. The optimized BGE contained 100 mM perfluorooctanoic acid with 200 mM ammonium hydroxide providing acceptable resolution of studied drugs in the MEKC step. In order to minimize interferences with matrix components and to preconcentrate target analytes, solid phase extraction was introduced as a clean-up step. The method was linear in the concentration range of 10-5000 ng mL(-1) and the limits of detection were in the range of 10-78 ng mL(-1). The method was demonstrated to be specific, sensitive, and reliable for the systematic toxicological analysis of these derivatives in urine samples.

  9. Design of the extraction process for terpenes and other volatiles from allspice by solid-phase microextraction and hydrodistillation.

    Science.gov (United States)

    Bajer, Tomáš; Ligor, Magdalena; Ligor, Tomasz; Buszewski, Bogusław

    2016-02-01

    Methods for the separation and determination of terpenes (mono- and sesqui-) and phenylpropanoids such as eugenol and methyleugenol from samples of allspice berries have been developed. Chromatographic analyses of isolated groups of compounds were carried out by means of gas chromatography coupled with mass spectrometry. A comparison of various types of solid-phase microextraction fibers was performed. The highest yields of terpenes were extracted by polydimethylsiloxane and divinylbenzene/Carboxen/polydimethylsiloxane fibers (almost the same for these two fibers), approximately twice as much as by Carbowax/divinylbenzene fiber. The highest amounts of monoterpenes were extracted by divinylbenzene/Carboxen/polydimethylsiloxane fiber, and the highest amounts of sesquiterpenes were extracted by polydimethylsiloxane fiber. Moreover, the effect of water addition on extraction yields as well as time and temperature of extraction were tested. Aroma profiles of extracts obtained by solid-phase microextraction and essential oil obtained by hydrodistillation of allspice berries were compared. The aroma profile of the divinylbenzene/Carboxen/polydimethylsiloxane fiber extract was similar to the aroma profile of essential oil. Particular characteristics of volatile allspice matters were presented. The linear retention indices for each compound were calculated.

  10. Evaluation of mercury in liquid waste processing facilities - Phase I report

    Energy Technology Data Exchange (ETDEWEB)

    Jain, V. [Savannah River Site (SRS), Aiken, SC (United States); Occhipinti, J. E. [Savannah River Site (SRS), Aiken, SC (United States); Shah, H. [Savannah River Site (SRS), Aiken, SC (United States); Wilmarth, W. R. [Savannah River Site (SRS), Aiken, SC (United States); Edwards, R. E. [Savannah River Site (SRS), Aiken, SC (United States)

    2015-07-01

    This report provides a summary of Phase I activities conducted to support an Integrated Evaluation of Mercury in Liquid Waste System (LWS) Processing Facilities. Phase I activities included a review and assessment of the liquid waste inventory and chemical processing behavior of mercury using a system by system review methodology approach. Gaps in understanding mercury behavior as well as action items from the structured reviews are being tracked. 64% of the gaps and actions have been resolved.

  11. Evaluation of Mercury in Liquid Waste Processing Facilities - Phase I Report

    Energy Technology Data Exchange (ETDEWEB)

    Jain, V. [Savannah River Site (SRS), Aiken, SC (United States); Occhipinti, J. [Savannah River Site (SRS), Aiken, SC (United States); Shah, H. [Savannah River Site (SRS), Aiken, SC (United States); Wilmarth, B. [Savannah River Site (SRS), Aiken, SC (United States); Edwards, R. [Savannah River Site (SRS), Aiken, SC (United States)

    2015-07-01

    This report provides a summary of Phase I activities conducted to support an Integrated Evaluation of Mercury in Liquid Waste System (LWS) Processing Facilities. Phase I activities included a review and assessment of the liquid waste inventory and chemical processing behavior of mercury using a system by system review methodology approach. Gaps in understanding mercury behavior as well as action items from the structured reviews are being tracked. 64% of the gaps and actions have been resolved.

  12. Liquid phase oxidation via heterogeneous catalysis organic synthesis and industrial applications

    CERN Document Server

    Clerici, Mario G

    2013-01-01

    Sets the stage for environmentally friendly industrial organic syntheses From basic principles to new and emerging industrial applications, this book offers comprehensive coverage of heterogeneous liquid-phase selective oxidation catalysis. It fully examines the synthesis, characterization, and application of catalytic materials for environmentally friendly organic syntheses. Readers will find coverage of all the important classes of catalysts, with an emphasis on their stability and reusability. Liquid Phase Oxidation via Heterogeneous Catalysis features contributions from an internation

  13. Scaling analysis of gas-liquid two-phase flow pattern in microgravity

    Science.gov (United States)

    Lee, Jinho

    1993-01-01

    A scaling analysis of gas-liquid two-phase flow pattern in microgravity, based on the dominant physical mechanism, was carried out with the goal of predicting the gas-liquid two-phase flow regime in a pipe under conditions of microgravity. The results demonstrated the effect of inlet geometry on the flow regime transition. A comparison of the predictions with existing experimental data showed good agreement.

  14. Study of surface-bonded dicationic ionic liquids as stationary phases for hydrophilic interaction chromatography.

    Science.gov (United States)

    Qiao, Lizhen; Li, Hua; Shan, Yuanhong; Wang, Shuangyuan; Shi, Xianzhe; Lu, Xin; Xu, Guowang

    2014-02-21

    In the present study, several geminal dicationic ionic liquids based on 1,4-bis(3-allylimidazolium)butane and 1,8-bis(3-allylimidazolium)octane in combination with different anions bromide and bis(trifluoromethanesulphonyl)imide were prepared and then bonded to the surface of 3-mercaptopropyl modified silica materials through the "thiol-ene" click chemistry as stationary phases for hydrophilic interaction chromatography (HILIC). Compared with their monocationic analogues, the dicationic ionic liquids stationary phases presented effective retention and good selectivity for typical hydrophilic compounds under HILIC mode with the column efficiency as high as 130,000 plates/m. Moreover, the influence of different alkyl chain spacer between dications and combined anions on the retention behavior and selectivity of the dicationic ionic liquids stationary phases under HILIC mode was displayed. The results indicated that the longer linkage chain would decrease the hydrophilicity and retention on the dicationic ionic liquid stationary phase, and while differently combined anions had no difference due to the exchangeability under the common HILIC mobile phase with buffer salt. Finally, the retention mechanism was investigated by evaluating the effect of chromatographic factors on retention, including the water content in the mobile phase, the mobile phase pH and buffer salt concentration. The results showed that the dicationic ionic liquids stationary phases presented a mixed-mode retention behavior with HILIC mechanism and anion exchange.

  15. The Plastic and Liquid Phases of CCl$_3$Br Studied by Molecular Dynamics Simulations

    CERN Document Server

    Caballero, Nirvana; Carignano, Marcelo; Serra, Pablo

    2013-01-01

    We present a molecular dynamics study of the liquid and plastic crystalline phases of CCl$_3$Br. We investigated the short-range orientational order using a recently developed classification method and we found that both phases behave in a very similar way. The only differences occur at very short molecular separations, which are shown to be very rare. The rotational dynamics was explored using time correlation functions of the molecular bonds. We found that the relaxation dynamics corresponds to an isotropic diffusive mode for the liquid phase, but departs from this behavior as the temperature is decreased and the system transitions into the plastic phase.

  16. First application of supported ionic liquid phase (SILP) catalysis for continuous methanol carbonylation

    DEFF Research Database (Denmark)

    Riisager, Anders; Jørgensen, Betina; Wasserscheid, Peter

    2006-01-01

    A solid, silica-supported ionic liquid phase (SILP) rhodium iodide Monsanto-type catalyst system, [BMIM][Rh(CO)(2)I-2]-[BMIM]I -SiO2, exhibits excellent activity and selectivity towards acetyl products in fixed-bed, continuous gas-phase methanol carbonylation.......A solid, silica-supported ionic liquid phase (SILP) rhodium iodide Monsanto-type catalyst system, [BMIM][Rh(CO)(2)I-2]-[BMIM]I -SiO2, exhibits excellent activity and selectivity towards acetyl products in fixed-bed, continuous gas-phase methanol carbonylation....

  17. Gas-liquid phase transition in modified pseudopotential and “shelf Coulomb” ultracold plasma models

    Science.gov (United States)

    Butlitsky, M. A.; Zelener, B. B.; Zelener, B. V.

    2016-11-01

    Phase diagrams for the “shelf Coulomb” and the modified pseudopotential plasma models developed in our previous works are compared. Qualitative agreement is observed between gas-liquid phase transition region of “shelf Coulomb” model and liquid-gas structure region of modified pseudopotential one. The possibility of experimental finding of the phase transition in nonequilibrium ultracold Rydberg plasma is considered. Parameters (density, temperature, levels of Rydberg atoms) for such a transition are estimated. Conclusion is made that “shelf Coulomb” model phase transition is practically impossible to observe in equilibrium strongly coupled plasmas due to high neutral atoms density at low temperatures: T crit ≈ 0.076.

  18. Phase field simulation of monotectic transformation for liquid Ni-Cu-Pb alloys

    Institute of Scientific and Technical Information of China (English)

    LUO BingChi; WANG HaiPeng; WEI BingBo

    2009-01-01

    Based on the subregular solution model, the liquid phase separation of ternary (NixCu100-x)50Pb50monotectic alloys is simulated by the phase field method. It is found that if the surface segregation potential is not incorporated, the dynamic morphologies of alloy melt show a transition from disperse microstructure into bicontinuous microstructure with the increase of fluidity parameter. When the sur-face segregation potential is coupled, Pb-rich phase migrates preferentially to the surface of the liquid alloy, and the Ni-rich phase depends on the Pb-rich phase to nucleate. With the extension of the phase separation time, the surface layer is formed through coagulation and growth, and its thickness gradu-ally increases. The Ni-rich phase migrates to the central part, and finally a two-layer core-shell micro-structure is produced. The concentration in the surface layer fluctuates more conspicuously than that inside the bulk phase, which subsequently transfers from the surface to the interior by a wave. The fluid field near the liquid-liquid interface is strong at the beginning of phase separation, and reduces later on. The surface segregation is essential to the formation of the surface layer, concentration profile variation, fluid field distribution and phase separation morphology.

  19. Gas-Liquid Two-Phase Axial Backmixing Through Structured Packing at Elevated Pressure

    Institute of Scientific and Technical Information of China (English)

    张鹏; 刘春江; 唐忠利; 袁希钢; 余国琮

    2003-01-01

    An experimental study of the extent of axial backmixing in both gas and liquid phases was conducted in a 150 mm ID column packed with Mellapak 250Y corrugated structured packing. The column was operated at pressures ranging from 0.3 MPa to 2.0 MPa with nitrogen and water flowing countercurrently through the packing.The amount of axial backmixing was experimentally evaluated by the pulse response techniques using hydrogen in gas phase and an aqueous solution of NaC1 in liquid phase as inert tracers. The response of the tracer was monitored by means of thermal conductivity in the gas phase and electrical conductance in the liquid phase. The experimentally determined residence time distribution (RTD) curves were interpreted in terms of the diffusion-type model. The results indicated that the axial backmixing in the gas increased notably with gas flowrate and slightly with operating pressure and liquid flowrate. The liquid-phase axial backmixing was an increasing function of both gas and liquid flowrates and insensitive to pressure. Various correlations were developed for reproducing the experimental mixing data. The agreement between experimental and correlated data appeared to be acceptable and within ±20% of difference.

  20. LIQUID-LIQUID PHASE EQUILIBRIUM OF POLYMER SOLUTIONS AND POLYMER BLENDS UNDER POSITIVE AND NEGATIVE PRESSURE

    Institute of Scientific and Technical Information of China (English)

    Attila R.Imre

    2003-01-01

    In this paper we would like to give a brief review about the extensibility of the liquid-liquid locus into the negative pressure region. Negative pressure states are hardly explored; most researchers believe that the pressure scale ends at p = 0.We would like to show that this is not true, thep = 0 point is not a special point for liquids, it can be "easily" crossed. We are going to give a few example, where the extension of liquid-liquid locus for polymer blends and solutions below p = 0 gives us some interesting results, like the merging of UCST and LCST branches in weakly interacting polymer solutions or the reason why most UCST blends exhibit pressure induced immiscibility. Also, we will see what happens with the immiscibility island of aqueous polymer solutions when - reaching the critical molar mass - it "disappears".

  1. A Computer Model for Analyzing Volatile Removal Assembly

    Science.gov (United States)

    Guo, Boyun

    2010-01-01

    A computer model simulates reactional gas/liquid two-phase flow processes in porous media. A typical process is the oxygen/wastewater flow in the Volatile Removal Assembly (VRA) in the Closed Environment Life Support System (CELSS) installed in the International Space Station (ISS). The volatile organics in the wastewater are combusted by oxygen gas to form clean water and carbon dioxide, which is solved in the water phase. The model predicts the oxygen gas concentration profile in the reactor, which is an indicator of reactor performance. In this innovation, a mathematical model is included in the computer model for calculating the mass transfer from the gas phase to the liquid phase. The amount of mass transfer depends on several factors, including gas-phase concentration, distribution, and reaction rate. For a given reactor dimension, these factors depend on pressure and temperature in the reactor and composition and flow rate of the influent.

  2. Frustrated smectic liquid crystalline phases in lactic acid derivatives

    Science.gov (United States)

    Glogarová, M.; Novotná, V.

    2016-08-01

    We have prepared and studied a series of compounds with different types of molecular core and lactate unit in the chiral terminal chain. We draw a survey and comparison of their mesomorphic properties with respect to the occurrence of twist grain boundary (TGB) phases. The materials exhibit extremely wide TGBA phase more than 60K broad, unique TGBA-TGBC-SmC*-SmCA* phase sequence and unique re-entrant TGBA phase below the SmA phase. TGB phases have been induced in binary mixtures of molecules with different molecular shape and chirality (chiral lactic acid derivative and non-chiral hockey-stick mesogen). Unique effect is observed for compounds with TGBA phase, where the applied electric field transforms the planar texture into the homeotropic one, homogeneously dark in crossed polarizers. The process is analogy of the Frederiks transition so far known only for nematics. This effect, changing the bright state to the dark one, is promising for applications.

  3. Characterization of the volatile fraction emitted by phloems of four pinus species by solid-phase microextraction and gas chromatography-mass spectrometry.

    Science.gov (United States)

    Santos, A M; Vasconcelos, T; Mateus, E; Farrall, M H; Gomes da Silva, M D R; Paiva, M R; Branco, M

    2006-02-10

    Pine forests constitute some of the most important renewable resources supplying timber, paper and chemical industries, among other functions. Characterization of the volatiles emitted by different Pinus species has proven to be an important tool to decode the process of host tree selection by herbivore insects, some of which cause serious economic damage to pines. Variations in the relative composition of the bouquet of semiochemicals are responsible for the outcome of different biological processes, such as mate finding, egg-laying site recognition and host selection. The volatiles present in phloem samples of four pine species, P. halepensis, P. sylvestris, P. pinaster and P. pinea, were identified and characterized with the aim of finding possible host-plant attractants for native pests, such as the bark beetle Tomicus piniperda. The volatile compounds emitted by phloem samples of pines were extracted by headspace solid-phase micro extraction, using a 2cm 50/30mm divinylbenzene/carboxen/polydimethylsiloxane table flex solid-phase microextraction fiber and its contents analyzed by high-resolution gas chromatography, using flame ionization and a non polar and chiral column phases. The components of the volatile fraction emitted by the phloem samples were identified by mass spectrometry using time-of-flight and quadrupole mass analyzers. The estimated relative composition was used to perform a discriminant analysis among pine species, by means of cluster and principal component analysis. It can be concluded that it is possible to discriminate pine species based on the monoterpenes emissions of phloem samples.

  4. Direct MD simulation of liquid-solid phase equilibria for two-component plasmas

    CERN Document Server

    Schneider, A S; Horowitz, C J; Berry, D K

    2011-01-01

    We determine the liquid-solid phase diagram for carbon-oxygen plasma mixtures using two-phase MD simulations. We identified liquid, solid, and interface regions using a bond angle metric. To study finite size effects, we perform 55296 ion simulations and compare to earlier 27648 ion results. To help monitor non-equilibrium effects, we calculate diffusion constants $D_i$. We find that $D_O$ for oxygen ions in the solid is much smaller than $D_C$ for carbon ions and that both diffusion constants are 80 or more times smaller than diffusion constants in the liquid phase. There is excellent agreement between our phase diagram and that predicted by Medin and Cumming. This suggests that errors from finite size and non-equilibrium effects are small and that the carbon-oxygen phase diagram is now accurately known.

  5. Non-congruence of liquid-gas phase transition of asymmetric nuclear matter

    CERN Document Server

    Maruyama, Toshiki

    2012-01-01

    We first explore the liquid-gas mixed phase in a bulk calculation, where two phases coexist without the geometrical structures. In the case of symmetric nuclear matter, the system behaves congruently, and the Maxwell construction becomes relevant. For asymmetric nuclear matter, on the other hand, the phase equilibrium is no more attained by the Maxwell construction since the liquid and gas phases are non-congruent; the particle fractions become completely different with each other. One of the origins of such non-congruence is attributed to the large symmetry energy. Subsequently we explore the charge-neutral nuclear matter with electrons by fully applying the Gibbs conditions to figure out the geometrical (pasta) structures in the liquid-gas mixed phase. We emphasize the effects of the surface tension and the Coulomb interaction on the pasta structures. We also discuss the thermal effects on the pasta structures.

  6. Numerical Simulation of Erosion-Corrosion in the Liquid Solid Two-Phase Flow

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Erosion-corrosion of liquid-solid two-phase flow occurring in a pipe with sudden expansion in cross section is numerically simulated in this paper. The global model for erosion-corrosion process includes three main components: the liquid-solid two-phase flow model, erosion model and corrosion model. The Euierian-Lagranglan approach is used to simulate liquid-solid two-phase flow, while the stochastic trajectory model was adopted to obtain properties of particle phase. Two-way coupling effect between the fluid and the particle phase is considered in the model. The accuracy of the models is tested by the data in the reference. The comparison shows that the model is basically correct and feasible.

  7. Use of ionic liquids as stationary phases in hyphenated gas chromatography techniques.

    Science.gov (United States)

    Ragonese, Carla; Sciarrone, Danilo; Tranchida, Peter Quinto; Dugo, Paola; Mondello, Luigi

    2012-09-14

    In the past decades a consistent number of ionic liquids have been specifically synthesized and evaluated as stationary phase in gas chromatography. Ionic liquid, also defined as "molten salts", are a class of organic non-molecular solvents liquid at room temperature (RTILs) that satisfy most of the requirements of a GC stationary phase, among which a high viscosity, the possibility to tune the selectivity (by changing the cation-anion combination) and a high thermal stability. The choice of the proper stationary phase plays a key role in the improvement/optimization of a GC method, and although the use of IL as stationary phases is still not well-established, the general interest in their applications has greatly increased, thanks to their particular properties. The present contribution provides an overview on recent evaluations and applications of IL stationary phases, focusing in particular on the use of these novel tools in hyphenated GC-based techniques.

  8. Phase diagrams of mixtures of a polymer and a cholesteric liquid crystal under an external field.

    Science.gov (United States)

    Matsuyama, Akihiko

    2014-11-14

    We present a mean field theory to describe phase behaviors in mixtures of a polymer and a cholesteric liquid crystal under an external magnetic or electric field. Taking into account a chiral coupling between a polymer and a liquid crystal under the external field, we examine twist-untwist phase transitions and phase separations in the mixtures. It is found that a cholesteric-nematic phase transition can be induced by not only the external field but also concentration and temperature. Depending on the strength of the external field, we predict cholesteric-paranematic (Ch+pN), nematic-paranematic (N+pN), cholesteric-nematic (Ch+N) phase separations, etc., on the temperature-concentration plane. We also discuss mixtures of a non-chiral nematic liquid crystal and a chiral dopant.

  9. Liquid-liquid equilibrium of water + PEG 8000 + magnesium sulfate or sodium sulfate aqueous two-phase systems at 35°C: experimental determination and thermodynamic modeling

    Directory of Open Access Journals (Sweden)

    B. D. Castro

    2005-09-01

    Full Text Available Liquid-liquid extraction using aqueous two-phase systems is a highly efficient technique for separation and purification of biomolecules due to the mild properties of both liquid phases. Reliable data on the phase behavior of these systems are essential for the design and operation of new separation processes; several authors reported phase diagrams for polymer-polymer systems, but data on polymer-salt systems are still relatively scarce. In this work, experimental liquid-liquid equilibrium data on water + polyethylene glycol 8000 + magnesium sulfate and water + polyethylene glycol 8000 + sodium sulfate aqueous two-phase systems were obtained at 35°C. Both equilibrium phases were analyzed by lyophilization and ashing. Experimental results were correlated with a mass-fraction-based NRTL activity coefficient model. New interaction parameters were estimated with the Simplex method. The mean deviations between the experimental and calculated compositions in both equilibrium phases is about 2%.

  10. Energy of formation for AgIn liquid binary alloys along the line of phase separation

    CERN Document Server

    Bhuiyan, G M; Ziauddin-Ahmed, A Z

    2003-01-01

    We have investigated the energy of formation for AgIn liquid binary alloys along the solid-liquid phase separation line. A microscopic theory based on the first order perturbation has been applied. The interionic interaction and a reference liquid are the fundamental components of the theory. These are described by a local pseudopotential and the hard sphere liquids, respectively. The results of calculations reveal a characteristic feature that the energy of formation becomes minimum at the equiatomic composition, and thus indicates maximal mix-ability at this concentration. The energy of formation at a particular thermodynamic state that is at T 1173 K predicts the experimental trends fairly well.

  11. Cloud Point and Liquid-Liquid Equilibrium Behavior of Thermosensitive Polymer L61 and Salt Aqueous Two-Phase System.

    Science.gov (United States)

    Rao, Wenwei; Wang, Yun; Han, Juan; Wang, Lei; Chen, Tong; Liu, Yan; Ni, Liang

    2015-06-25

    The cloud point of thermosensitive triblock polymer L61, poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO), was determined in the presence of various electrolytes (K2HPO4, (NH4)3C6H5O7, and K3C6H5O7). The cloud point of L61 was lowered by the addition of electrolytes, and the cloud point of L61 decreased linearly with increasing electrolyte concentration. The efficacy of electrolytes on reducing cloud point followed the order: K3C6H5O7 > (NH4)3C6H5O7 > K2HPO4. With the increase in salt concentration, aqueous two-phase systems exhibited a phase inversion. In addition, increasing the temperature reduced the concentration of salt needed that could promote phase inversion. The phase diagrams and liquid-liquid equilibrium data of the L61-K2HPO4/(NH4)3C6H5O7/K3C6H5O7 aqueous two-phase systems (before the phase inversion but also after phase inversion) were determined at T = (25, 30, and 35) °C. Phase diagrams of aqueous two-phase systems were fitted to a four-parameter empirical nonlinear expression. Moreover, the slopes of the tie-lines and the area of two-phase region in the diagram have a tendency to rise with increasing temperature. The capacity of different salts to induce aqueous two-phase system formation was the same order as the ability of salts to reduce the cloud point.

  12. Incorporation of ionic liquid into porous polymer monoliths to enhance the separation of small molecules in reversed-phase high-performance liquid chromatography.

    Science.gov (United States)

    Wang, Jiafei; Bai, Ligai; Wei, Zhen; Qin, Junxiao; Ma, Yamin; Liu, Haiyan

    2015-06-01

    An ionic liquid was incorporated into the porous polymer monoliths to afford stationary phases with enhanced chromatographic performance for small molecules in reversed-phase high-performance liquid chromatography. The effect of the ionic liquid in the polymerization mixture on the performance of the monoliths was studied in detail. While monoliths without ionic liquid exhibited poor resolution and low efficiency, the addition of ionic liquid to the polymerization mixture provides highly increased resolution and high efficiency. The chromatographic performances of the monoliths were demonstrated by the separations of various small molecules including aromatic hydrocarbons, isomers, and homologues using a binary polar mobile phase. The present column efficiency reached 27 000 plates/m, which showed that the ionic liquid monoliths are alternative stationary phases in the separation of small molecules by high-performance liquid chromatography.

  13. Orientational phase transition in cubic liquid crystals with positional order

    OpenAIRE

    Pokrovsky, V.L.; Saidachmetov, P.A.

    1988-01-01

    An electric field can give rise to a shear deformation of a cubic liquid crystal with long-range positional order fixed by two plates. The critical value of the field does not depend on the size of the system and depends crucially on the orientation.

  14. Student Understanding of Liquid-Vapor Phase Equilibrium

    Science.gov (United States)

    Boudreaux, Andrew; Campbell, Craig

    2012-01-01

    Student understanding of the equilibrium coexistence of a liquid and its vapor was the subject of an extended investigation. Written assessment questions were administered to undergraduates enrolled in introductory physics and chemistry courses. Responses have been analyzed to document conceptual and reasoning difficulties in sufficient detail to…

  15. Analysis of Developing Gas/liquid Two-Phase Flows

    Energy Technology Data Exchange (ETDEWEB)

    Elena A. Tselishcheva; Michael Z. Podowski; Steven P. Antal; Donna Post Guillen; Matthias Beyer; Dirk Lucas

    2010-06-01

    The goal of this work is to develop a mechanistically based CFD model that can be used to simulate process equipment operating in the churn-turbulent regime. The simulations were performed using a state-of-the-art computational multiphase fluid dynamics code, NPHASE–CMFD [Antal et al,2000]. A complete four-field model, including the continuous liquid field and three dispersed gas fields representing bubbles of different sizes, was first carefully tested for numerical convergence and accuracy, and then used to reproduce the experimental results from the TOPFLOW test facility at Forschungszentrum Dresden-Rossendorf e.V. Institute of Safety Research [Prasser et al,2007]. Good progress has been made in simulating the churn-turbulent flows and comparison the NPHASE-CMFD simulations with TOPFLOW experimental data. The main objective of the paper is to demonstrate capability to predict the evolution of adiabatic churn-turbulent gas/liquid flows. The proposed modelling concept uses transport equations for the continuous liquid field and for dispersed bubble fields [Tselishcheva et al, 2009]. Along with closure laws based on interaction between bubbles and continuous liquid, the effect of height on air density has been included in the model. The figure below presents the developing flow results of the study, namely total void fraction at different axial locations along the TOPFLOW facility test section. The complete model description, as well as results of simulations and validation will be presented in the full paper.

  16. Data acquisition and quantitative analysis of stable hydrogen isotope in liquid and gas in the liquid phase catalytic exchange process

    Energy Technology Data Exchange (ETDEWEB)

    Choi, H. J.; Lee, H. S.; Kim, K. R.; Cheong, H. S.; Ahn, D. H.; Lee, S. H.; Paek, S. W.; Kang, H. S.; Kim, J. G

    2001-01-01

    A pilot plant for the Liquid Phase Catalytic Exchange process was built and has been operating to test the hydrophobic catalyst developed to remove the tritium generated at the CANDU nuclear power plants. The methods of quantitative analysis of hydrogen stable isotope were compared. Infrared spectroscopy was used for the liquid samples, and gas chromatography with hydrogen carrier gas showed the best result for gas samples. Also, a data acquisition system was developed to record the operation parameters. This record was very useful to investigate the causes of the system trip.

  17. Determination of three estrogens and bisphenol A by functional ionic liquid dispersive liquid-phase microextraction coupled with ultra-high performance liquid chromatography and ultraviolet detection.

    Science.gov (United States)

    Jiang, Yuehuang; Tang, Tingting; Cao, Zhen; Shi, Guoyue; Zhou, Tianshu

    2015-06-01

    A hydroxyl-functionalized ionic liquid, 1-hydroxyethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, was employed in an improved dispersive liquid-phase microextraction method coupled with ultra high performance liquid chromatography for the enrichment and determination of three estrogens and bisphenol A in environmental water samples. The introduced hydroxyl group acted as the H-bond acceptor that dispersed the ionic liquid effectively in the aqueous phase without dispersive solvent or external force. Fourier transform infrared spectroscopy indicated that the hydroxyl group of the cation of the ionic liquid enhanced the combination of extractant and analytes through the formation of hydrogen bonds. The improvement of the extraction efficiency compared with that with the use of alkyl ionic liquid was proved by a comparison study. The main parameters including volume of extractant, temperature, pH, and extraction time were investigated. The calibration curves were linear in the range of 5.0-1000 μg/L for estrone, estradiol, and bisphenol A, and 10.0-1000 μg/L for estriol. The detection limits were in the range of 1.7-3.4 μg/L. The extraction efficiency was evaluated by enrichment factor that were between 85 and 129. The proposed method was proved to be simple, low cost, and environmentally friendly for the determination of the four endocrine disruptors in environmental water samples.

  18. Gold nanoparticle decorated graphene oxide/silica composite stationary phase for high-performance liquid chromatography.

    Science.gov (United States)

    Liang, Xiaojing; Wang, Xusheng; Ren, Haixia; Jiang, Shengxiang; Wang, Licheng; Liu, Shujuan

    2014-06-01

    In the initial phase of this study, graphene oxide (GO)/silica was fabricated by assembling GO onto the silica particles, and then gold nanoparticles (GNPs) were used to modify the GO/silica to prepare a novel stationary phase for high-performance liquid chromatography. The new stationary phase could be used in both reversed-phase chromatography and hydrophilic interaction liquid chromatography modes. Good separations of alkylbenzenes, isomerides, amino acids, nucleosides, and nucleobases were achieved in both modes. Compared with the GO/silica phase and GNPs/silica phase, it is found that except for hydrophilicity, large π-electron systems, hydrophobicity, and coordination functions, this new stationary phase also exhibited special separation performance due to the combination of 2D GO with zero-dimensional GNPs.

  19. Brain-like associative learning using a nanoscale non-volatile phase change synaptic device array

    Directory of Open Access Journals (Sweden)

    Sukru Burc Eryilmaz

    2014-07-01

    Full Text Available Recent advances in neuroscience together with nanoscale electronic device technology have resulted in huge interests in realizing brain-like computing hardwares using emerging nanoscale memory devices as synaptic elements. Although there has been experimental work that demonstrated the operation of nanoscale synaptic element at the single device level, network level studies have been limited to simulations. In this work, we demonstrate, using experiments, array level associative learning using phase change synaptic devices connected in a grid like configuration similar to the organization of the biological brain. Implementing Hebbian learning with phase change memory cells, the synaptic grid was able to store presented patterns and recall missing patterns in an associative brain-like fashion. We found that the system is robust to device variations, and large variations in cell resistance states can be accommodated by increasing the number of training epochs. We illustrated the tradeoff between variation tolerance of the network and the overall energy consumption, and found that energy consumption is decreased significantly for lower variation tolerance.

  20. Solid-phase microextraction-gas chromatographic determination of volatile monoaromatic hydrocarbons in soil.

    Science.gov (United States)

    Zygmunt, B; Namiesnik, J

    2001-08-01

    Benzene, toluene, ethylbenzene, three isomers of xylene, and cumene have been isolated and enriched from soil samples by a combination of water extraction at room and elevated temperature and headspace-solid-phase microextraction before their gas chromatographic-mass spectrometric (GC-MS) determination. The conditions used for all stages of sample preparation and chromatographic analysis were optimized. Analytes sampled on a polydimethylsiloxane-coated solid-phase microextraction fiber were thermally desorbed in the split/splitless injector of a gas chromatograph (GC) coupled with a mass spectrometer (MS). The desorption temperature was optimized. The GC separation was performed in a capillary column. Detection limits were found to be of the order of ca. 1 ng g(-1). Relative recoveries of the analytes from soils were found to be highly dependent on soil organic-matter content and on compound identity; they ranged from ca 92 to 96% for sandy soil (extraction at room temperature) and from ca 27 to 55% for peaty soil (extraction at elevated temperature). A few real-world soil samples were analyzed; the individual monoaromatic hydrocarbon content ranged from below detection limits to 6.4 ng g(-1) for benzene and 8.1 for the total of p- + m-xylene.

  1. Phase equilibria and modeling of ammonium ionic liquid, C2NTf2, solutions.

    Science.gov (United States)

    Domańska, Urszula; Marciniak, Andrzej; Królikowski, Marek

    2008-01-31

    Novel quaternary ammonium ionic liquid, ethyl(2-hydroxyethyl)dimethylammonium bis(trifluomethylsulfonyl)imide (C2NTf2), has been prepared from N,N-dimethylethanolamine as a substrate. The paper includes a specific basic characterization of the synthesized compound by NMR and the basic thermophysical properties: the melting point, enthalpy of fusion, enthalpy of solid-solid phase transition, glass transition determined by the differential scanning calorimetry (DSC), temperature of decomposition, and water content. The density of the new compound was measured. The solid-liquid or liquid-liquid phase equilibria of binary mixtures containing {C2NTf2+water or an alcohol (propan-1-ol, butan-1-ol, hexan-1-ol, octan-1-ol, decan-1-ol), aromatic hydrocarbons (benzene, toluene), aliphatic hydrocarbons (n-hexane, n-octane), dimethylsulfoxide (DMSO), or tetrahydrofuran (THF)} have been measured by a dynamic method in a wide range of temperatures from 230 to 430 K. These data were correlated by means of the nonrandom two-liquid (NRTL) equation utilizing temperature-dependent parameters derived from the solid-liquid or liquid-liquid equilibrium. From the solubility results, the negative value of the partition coefficient of ionic liquid in binary system octan-1-ol/water (log P) at 298.15 K has been calculated.

  2. A powerful methodological approach combining headspace solid phase microextraction, mass spectrometry and multivariate analysis for profiling the volatile metabolomic pattern of beer starting raw materials.

    Science.gov (United States)

    Gonçalves, João L; Figueira, José A; Rodrigues, Fátima P; Ornelas, Laura P; Branco, Ricardo N; Silva, Catarina L; Câmara, José S

    2014-10-01

    The volatile metabolomic patterns from different raw materials commonly used in beer production, namely barley, corn and hop-derived products - such as hop pellets, hop essential oil from Saaz variety and tetra-hydro isomerized hop extract (tetra hop), were established using a suitable analytical procedure based on dynamic headspace solid-phase microextraction (HS-SPME) followed by thermal desorption gas chromatography-quadrupole mass spectrometry detection (GC-qMS). Some SPME extraction parameters were optimized. The best results, in terms of maximum signal recorded and number of isolated metabolites, were obtained with a 50/30 μm DVB/CAR/PDMS coating fiber at 40 °C for 30 min. A set of 152 volatile metabolites comprising ketones (27), sesquiterpenes (26), monoterpenes (19), aliphatic esters (19), higher alcohols (15), aldehydes (11), furan compounds (11), aliphatic fatty acids (9), aliphatic hydrocarbons (8), sulphur compounds (5) and nitrogen compounds (2) were positively identified. Each raw material showed a specific volatile metabolomic profile. Monoterpenes in hop essential oil and corn, sesquiterpenes in hop pellets, ketones in tetra hop and aldehydes and sulphur compounds in barley were the predominant chemical families in the targeted beer raw materials. β-Myrcene was the most dominant volatile metabolite in hop essential oil, hop pellets and corn samples while, in barley, the predominant volatile metabolites were dimethyl sulphide and 3-methylbutanal and, in tetra hop, 6-methyl-2-pentanone and 4-methyl-2-pentanone. Principal component analysis (PCA) showed natural sample grouping among beer raw materials.

  3. Restudy of the unusual phase behavior of the mesogen-jacketed liquid crystal polymers

    Institute of Scientific and Technical Information of China (English)

    ZHAO; Yongfeng; FAN; Xinghe; CHEN; Xiaofang; WAN; Xinhua

    2006-01-01

    A series of poly{2,5-bis[(4-butoxyphenyl)-oxycarbonyl]styrenes} (PBPCS) with low molecular weight distribution was synthesized by atom transfer radical polymerization (ATRP). The mesomorphic properties were investigated by differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and rheometer. PBPCS showed the phase transition from isotropic into liquid crystal (LC) phase, and the LC phase formed at high temperature and disappeared in the subsequent cooling procedure. Using the WAXD fiber pattern, the phase structure of the PBPCS at higher temperature showed hexagonal columnar nematic phase. Experimental results demonstrated that the driving force of the entropy is an important factor during the unusual LC phase formation of PBPCS.

  4. Liquid-phase microextraction in a microfluidic-chip

    DEFF Research Database (Denmark)

    Payán, María D. Ramos; Jensen, Henrik; Petersen, Nickolaj J.

    2012-01-01

    , methadone, haloperidol, loperamide, and pethidine were selected as model analytes, and they were extracted from alkaline sample solution, through the SLM, and into 10mM HCl or 100mM HCOOH functioning as acceptor phase. Subsequently, the acceptor phase was either analyzed off-line by capillary...

  5. Modulated liquid-crystal phases induced by polarity: Twist-bend, splay-bend, and blue phases

    Science.gov (United States)

    Selinger, Jonathan; Shamid, Shaikh; Allender, David

    2014-03-01

    Nematic liquid crystals exhibit flexoelectric couplings between polar order and gradients in the director field. When the couplings become strong enough, the uniform nematic phase can become unstable to the formation of a modulated polar phase. The question is then: What is the structure of the modulated polar phase? Classic work by Meyer and further studies by Dozov predicted two possible structures, known as twist-bend and splay-bend. One of these predictions, the twist-bend phase, has recently been identified in experiments on bent-core liquid crystals. Here, we investigate modulated polar phases through a combination of Landau theory and lattice simulations. We find a range of possibilities, including the twist-bend and splay-bend phases as well as polar blue phases, with 2D or 3D modulations of the director field and the polar order. We compare these polar blue phases with chiral blue phases, and discuss opportunities for observing them experimentally. Supported by NSF DMR-1106014.

  6. A validated high performance liquid chromatography method for the analysis of thymol and carvacrol in Thymus vulgaris L. volatile oil

    Directory of Open Access Journals (Sweden)

    H Hajimehdipoor

    2010-01-01

    Full Text Available Thymus vulgaris L. (Lamiaceae is a well-known medicinal plant that contains important compounds such as thymol and carvacrol and it has been used in many pharmaceutical dosage forms. Thymol and carvacrol in essential oils are often quantified by gas chromatography (GC technique but in this work, a validated and reliable high performance liquid chromatography (HPLC method has been developed for the analysis of these two components in T. vulgaris essential oil. The essential oil of the plant was analyzed by HPLC and GC techniques. The HPLC system consisted of ACE C 18 column and an isocratic acetonitrile:water (50:50 as the mobile phase which was kept at a flow rate of 1 ml/min. The method was validated for selectivity, linearity (r2 > 0.997 for both thymol and carvacrol, precision (intra-day 0.8-1.9, 1.7-2.6; and inter-day 3.5-4.5, 3.6-4.7 and recovery (97.7%, 97.6% for thymol and carvacrol, respectively. The limits of detection (LODs and limits of quantization (LOQs were calculated to be 2.8, 0.6 μg/ml and 8.6, 1.8 μg/ml for thymol and carvacrol, respectively. The GC system consisted of flame ionization detector (FID and CP-SIL 8 column. The concentrations of thymol and carvacrol in essential oil obtained by HPLC (41.2%, 4.3% and GC (40.7%, 4.2% were compared by statistical methods and they showed good agreement.

  7. A validated high performance liquid chromatography method for the analysis of thymol and carvacrol in Thymus vulgaris L. volatile oil.

    Science.gov (United States)

    Hajimehdipoor, H; Shekarchi, M; Khanavi, M; Adib, N; Amri, M

    2010-07-01

    Thymus vulgaris L. (Lamiaceae) is a well-known medicinal plant that contains important compounds such as thymol and carvacrol and it has been used in many pharmaceutical dosage forms. Thymol and carvacrol in essential oils are often quantified by gas chromatography (GC) technique but in this work, a validated and reliable high performance liquid chromatography (HPLC) method has been developed for the analysis of these two components in T. vulgaris essential oil. The essential oil of the plant was analyzed by HPLC and GC techniques. The HPLC system consisted of ACE C(18) column and an isocratic acetonitrile:water (50:50) as the mobile phase which was kept at a flow rate of 1 ml/min. The method was validated for selectivity, linearity (r(2) > 0.997 for both thymol and carvacrol), precision (intra-day 0.8-1.9, 1.7-2.6; and inter-day 3.5-4.5, 3.6-4.7) and recovery (97.7%, 97.6%) for thymol and carvacrol, respectively. The limits of detection (LODs) and limits of quantization (LOQs) were calculated to be 2.8, 0.6 µg/ml and 8.6, 1.8 µg/ml for thymol and carvacrol, respectively. The GC system consisted of flame ionization detector (FID) and CP-SIL 8 column. The concentrations of thymol and carvacrol in essential oil obtained by HPLC (41.2%, 4.3%) and GC (40.7%, 4.2%) were compared by statistical methods and they showed good agreement.

  8. Determination of volatile and non-volatile products of milk fermentation processes using capillary zone electrophoresis and solid phase microextraction coupled to gas chromatography.

    Science.gov (United States)

    Ligor, Magdalena; Jarmalaviciene, Reda; Szumski, Michal; Maruska, Audrius; Buszewski, Boguslaw

    2008-08-01

    The aim of the investigations was to develop analytical methods for the determination of selected volatile and non-volatile organic compounds numbering among the final products of milk fermentation. The analyzed compounds were as follows: biacetyl and carboxylic acids (formic, acetic, citric, and lactic). The model yogurt was prepared under controlled conditions in our laboratory by addition of the selected bacteria (Lactobacillus bulgaricus and Streptococcus thermophilus) to the milk sample. The temperature, time, and stirring were controlled during the fermentation process. Factors considered in SPMPE-GC-FID method development included fiber exposure time, salt addition, temperature of extraction, and temperature of desorption. Various SPME fibers, for example with PDMS, CAR/PDMS, PA, and PDMS/DVB coatings, were tested to obtain the highest recovery of the investigated compounds extracted from yogurt samples. Based on these preliminary experiments, qualitative and quantitative analyses for the determination of biacetyl were performed by SPME-GC-FID. Moreover, a capillary zone electrophoresis method was developed for the determination of carboxylic acids in the yogurt samples. The buffer composition as well as deproteinization by acetonitrile were found to have a crucial effect on the analysis.

  9. Experimental hydrophobicity parameters of perfluorinated alkylated substances from reversed-phase high performance liquid chromatography

    NARCIS (Netherlands)

    de Voogt, P.; Zurano, L.; Serné, P.; Haftka, J.J.H.

    2012-01-01

    Capacity factors of perfluorinated alkylated substances were obtained from isocratic reversed-phase high-performance liquid chromatography-mass spectrometry experiments at different organic modifier strengths of the mobile phase. The resulting capacity factor v. modifier strengths plots were extrapo

  10. Global phase diagram and quantum spin liquids in a spin-1/2 triangular antiferromagnet

    Science.gov (United States)

    Gong, Shou-Shu; Zhu, W.; Zhu, J.-X.; Sheng, D. N.; Yang, Kun

    2017-08-01

    We study the spin-1 /2 Heisenberg model on the triangular lattice with the nearest-neighbor J1>0 , the next-nearest-neighobr J2>0 Heisenberg interactions, and the additional scalar chiral interaction Jχ(S⃗i×S⃗j) .S⃗k for the three spins in all the triangles using large-scale density matrix renormalization group calculation on cylinder geometry. With increasing J2 (J2/J1≤0.3 ) and Jχ (Jχ/J1≤1.0 ) interactions, we establish a quantum phase diagram with the magnetically ordered 120∘, stripe, and noncoplanar tetrahedral phase. In between these magnetic order phases, we find a chiral spin liquid (CSL) phase, which is identified as a ν =1 /2 bosonic fractional quantum Hall state with possible spontaneous rotational symmetry breaking. By switching on the chiral interaction, we find that the previously identified spin liquid in the J1-J2 triangular model (0.08 ≲J2/J1≲0.15 ) shows a phase transition to the CSL phase at very small Jχ. We also compute the spin triplet gap in both spin liquid phases, and our finite-size results suggest a large gap in the odd topological sector but a small or vanishing gap in the even sector. We discuss the implications of our results on the nature of the spin liquid phases.

  11. STUDY ON THE PHASE TRANSITION KINETICS OF THERMOTROPIC LIQUID CRYSTALLINE AROMATIC-ALIPHATIC COPOLYESTER

    Institute of Scientific and Technical Information of China (English)

    LI Minhui; WANG Xiaogong; LIU Deshan; ZHOU Qixiang

    1991-01-01

    The phase transition kinetics of thermotropic liquid crystalline aromatic-aliphatic regular copolyester:(X) were studied by DSC. By means of Kissinger's method the kinetic equation and parameters including activation energy, rate order and preexponential factor for phase transition from nematic to isotropic were obtained. The activation energy from crystal to nematic was also presented.

  12. Preparation and Characterization of Silicone Liquid Core/Polymer Shell Microcapsules via Internal Phase Separation

    DEFF Research Database (Denmark)

    Gonzalez, Lidia; Kostrzewska, Malgorzata; Ma, Baoguang

    2014-01-01

    Microcapsules with a silicone liquid core surrounded by a polymeric shell were synthesisedthrough the controlled phase separation. The dispersed silicone phase consisted of the shellpolymer PMMA, a good solvent for the PMMA (dichloromethane, DCM) and a poor solvent(methylhydrosiloxane dimethylsil...

  13. Headspace Hanging Drop Liquid Phase Microextraction and Gas Chromatography-Mass Spectrometry for the Analysis of Flavors from Clove Buds

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Mi Jin; Shin, Yeon Jae; Oh, Se Yeon; Kim, Nam Sun; Kim, Kun; Lee, Dong Sun [Seoul Women' s University, Seoul (Korea, Republic of)

    2006-02-15

    A novel sample pretreatment technique, headspace hanging drop liquid phase microextraction (HS-LPME) was studied and applied to the determination of flavors from solid clove buds by gas chromatography-mass spectrometry (GC-MS). Several parameters affecting on HS-LPME such as organic solvent drop volume, extraction time, extraction temperature and phase ratio were investigated. 1-Octanol was selected as the extracting solvent, drop size was fixed to 0.6 μL. 60 min extraction time at 25 .deg. C was chosen. HS-LPME has the good efficiency demonstrated by the higher partition equilibrium constant (K{sub lh}) values and concentration factor (CF) values. The limits of detection (LOD) were 1.5-3.2 ng. The amounts of eugenol, β-caryophyllene and eugenol acetate from the clove bud sample were 1.90 mg/g, 1.47 mg/g and 7.0 mg/g, respectively. This hanging drop based method is a simple, fast and easy sample enrichment technique using minimal solvent. HSLPME is an alternative sample preparation method for the analysis of volatile aroma compounds by GC-MS.

  14. Physico-Chemical Properties and Phase Behaviour of Pyrrolidinium-Based Ionic Liquids

    Directory of Open Access Journals (Sweden)

    Urszula Domańska

    2010-04-01

    Full Text Available A review of the relevant literature on 1-alkyl-1-methylpyrrolidinium-based ionic liquids has been presented. The phase diagrams for the binary systems of {1-ethyl-1-methylpyrrolidinium trifluoromethanesulfonate (triflate [EMPYR][CF3SO3] + water, or + 1-butanol} and for the binary systems of {1-propyl-1-methylpyrrolidinium trifluoromethanesulfonate (triflate [PMPYR][CF3SO3] + water, or + an alcohol (1-butanol, 1-hexanol, 1-octanol, 1-decanol} have been determined at atmospheric pressure using a dynamic method. The influence of alcohol chain length was discussed for the [PMPYR][CF3SO3]. A systematic decrease in the solubility was observed with an increase of the alkyl chain length of an alcohol. (Solid + liquid phase equilibria with complete miscibility in the liquid phase region were observed for the systems involving water and alcohols. The solubility of the ionic liquid increases as the alkyl chain length on the pyrrolidinium cation increases. The correlation of the experimental data has been carried out using the Wilson, UNIQUAC and the NRTL equations. The phase diagrams reported here have been compared to the systems published earlier with the 1-alkyl-1-methylpyrrolidinium-based ionic liquids. The influence of the cation and anion on the phase behaviour has been discussed. The basic thermal properties of pure ILs, i.e., melting temperature and the enthalpy of fusion, the solid-solid phase transition temperature and enthalpy have been measured using a differential scanning microcalorimetry technique.

  15. Characterization of rhamnolipids by liquid chromatography/mass spectrometry after solid-phase extraction.

    Science.gov (United States)

    Behrens, Beate; Engelen, Jeannine; Tiso, Till; Blank, Lars Mathias; Hayen, Heiko

    2016-04-01

    Rhamnolipids are surface-active agents with a broad application potential that are produced in complex mixtures by bacteria of the genus Pseudomonas. Analysis from fermentation broth is often characterized by laborious sample preparation and requires hyphenated analytical techniques like liquid chromatography coupled to mass spectrometry (LC-MS) to obtain detailed information about sample composition. In this study, an analytical procedure based on chromatographic method development and characterization of rhamnolipid sample material by LC-MS as well as a comparison of two sample preparation methods, i.e., liquid-liquid extraction and solid-phase extraction, is presented. Efficient separation was achieved under reversed-phase conditions using a mixed propylphenyl and octadecylsilyl-modified silica gel stationary phase. LC-MS/MS analysis of a supernatant from Pseudomonas putida strain KT2440 pVLT33_rhlABC grown on glucose as sole carbon source and purified by solid-phase extraction revealed a total of 20 congeners of di-rhamnolipids, mono-rhamnolipids, and their biosynthetic precursors 3-(3-hydroxyalkanoyloxy)alkanoic acids (HAAs) with different carbon chain lengths from C8 to C14, including three rhamnolipids with uncommon C9 and C11 fatty acid residues. LC-MS and the orcinol assay were used to evaluate the developed solid-phase extraction method in comparison with the established liquid-liquid extraction. Solid-phase extraction exhibited higher yields and reproducibility as well as lower experimental effort.

  16. Numerical Modeling of Thermocapillary Deformation and Film Breakdown in a Locally Heated Thin Horizontal Volatile Liquid Layer

    Directory of Open Access Journals (Sweden)

    Barakhovskaya Ella

    2016-01-01

    Full Text Available The problem of thermocapillary deformation and film breakdown in a thin horizontal layer of viscous incompressible liquid with a free surface is considered. The deformable liquid layer is locally heated. The problem of thermocapillary deformation of the locally heated horizontal liquid layer has been solved numerically for two-dimensional unsteady case. The lubrication approximation theory is used. Capillary pressure, viscosity and gravity are taken into account. Evaporating rate is supposed to be proportional to the temperature difference between the liquid and ambient. Heat transfer in the substrate is also simulated. The numerical algorithm for the joint solution of the energy equation and the evolution equation for the thickness of liquid layer has been developed. The model predicts the thermocapillary deformation of the liquid surface and the formation of dry spots. The dynamics of liquid surface, the dry spots formation and the velocity of the contact line have been calculated. The deformation of the free surface has been calculated for different values of the heating power and thickness of the liquid layer. The effect of surface tension coefficient and wetting contact angle on the velocity of the contact line motion has been analyzed. It has been obtained that the velocity of the contact line increases with the increase of the wetting contact angle value and of the surface tension coefficient.

  17. Solvent-based dissolution method to sample gas-phase volatile organic compounds for compound-specific isotope analysis.

    Science.gov (United States)

    Bouchard, Daniel; Hunkeler, Daniel

    2014-01-17

    An investigation was carried out to develop a simple and efficient method to collect vapour samples for compound specific isotope analysis (CSIA) by bubbling vapours through an organic solvent (methanol or ethanol). The compounds tested were benzene and trichloroethylene (TCE). The dissolution efficiency was tested for different air volume injections, using flow rates ranging from 25ml/min to 150ml/min and injection periods varying between 10 and 40min. Based on the results, complete mass recovery for benzene and TCE in both solvents was observed for the flow rates of 25 and 50ml/min. However, small mass loss was observed at increased flow rate. At 150ml/min, recovery was on average 80±17% for benzene and 84±10% for TCE, respectively in methanol and ethanol. The δ(13)C data measured for benzene and TCE dissolved in both solvents were reproducible and were stable independently of the volume of air injected (up to 6L) or the flow rate used. The stability of δ(13)C values hence underlines no isotopic fractionation due to compound-solvent interaction or mass loss. The development of a novel and simple field sampling technique undertaken in this study will facilitate the application of CSIA to diverse gas-phase volatile organic compound studies, such as atmospheric emissions, soil gas or vapour intrusion.

  18. Phase separation of monomer in liquid crystal mixtures and surface morphology in polymer-stabilized vertical alignment liquid crystal displays

    Energy Technology Data Exchange (ETDEWEB)

    Lyu, Jae Jin; Lee, Jun Hyup; Kim, Kyeong Hyeon [Development Center, LCD Business, SAMSUNG Electronics Co. LTD., Tangjeong-Myeon, Asan, Chungnam 336-741 (Korea, Republic of); Kikuchi, Hirotsuku; Higuchi, Hiroki [Institute for Materials Chemistry and Engineering, Kyushu University, 6-1 Kasuga-Koen, Kasuga 816-8580 (Japan); Kim, Dae Hyun; Lee, Seung Hee, E-mail: jsquare.lyu@samsung.com, E-mail: lsh1@chonbuk.ac.kr [Department of BIN Fusion Technology and Department of Polymer-Nano Science and Technology, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of)

    2011-08-17

    The polymer-stabilized vertically aligned (PS-VA) liquid crystal display (LCD) driving mode has high potential for manufacturing low power consuming displays due to the higher transmittance and fast response as compared with the existing patterned vertically aligned and multi-domain vertically aligned modes. In this paper we have investigated the reaction mechanisms of monomer-liquid crystal blends to form a surface pre-tilt angle of liquid crystal in vertical alignment LCD associated with a fishbone electrode structure. The observed sizes of polymer bumps formed on the substrates were found to be dependent on the exposed UV wavelength and were almost equal in both top and bottom substrates. When a large UV wavelength was used, the phase separation mechanism of monomer in PS-VA mode was found nearly isotropic rather than anisotropic in contrast to the previous studies.

  19. Lattice Boltzmann Simulation of 3D Nematic Liquid Crystal near Phase Transition

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jun; TAO Rui-Bao

    2002-01-01

    Phase transition between nematic and isotropic liquid crystal is a very weak first order phase transition.We avoid to use the normal Landau-de Gennes's free energy that reduces a strong first order transition, and set up adata base of free energy calculated by means of Tao-Sheng Lin's extended molecular field theory that can explain theexperiments of the equilibrium properties of nematic liquid crystal very well. Then we use the free energy method oflattice Boltzmann developed by Oxford group to study the phase decomposition, pattern formation in the flow of theliquid crystal near transition temperature.

  20. Setting up a liquid crystal phase screen to simulate atmospheric turbulence

    Science.gov (United States)

    Giles, Michael K.; Seward, Anthony J.; Vorontsov, Mikhail A.; Rha, Jungtae; Jimenez, Ray

    2000-11-01

    Phase screens are often used to simulate atmospheric turbulence in systems designed to test adaptive optics techniques. This paper presents the design and implementation of a dynamic phase screen using a simple and inexpensive twisted nematic liquid crystal display taken from a video projector and placed in a pupil plane. The details of the optical system layout, the system alignment procedure, and the operating parameters of the liquid crystal display are discussed. Examples of turbulence (having strength and statistics similar to measured values of atmospheric turbulence in a variety of scenarios) are written to the phase screen, and the effects of the turbulence on image quality are measured and presented.

  1. Hyperresolving phase-only filters with an optically addressable liquid crystal spatial light modulator.

    Science.gov (United States)

    McOrist, J; Sharma, M D; Sheppard, C J R; West, E; Matsuda, K

    2003-01-01

    Hyperresolving (sometimes called 'superresolving' or 'ultraresolving') phase-only filters can be generated using an optically addressable liquid crystal spatial light modulator. This approach avoids the problems of low efficiency, and coupling between amplitude and phase modulation, that arise when using conventional liquid crystal modulators. When addressed by a programmed light intensity distribution, it allows filters to be changed rapidly to modify the response of a system or permit the investigation of different filter designs. In this paper we present experimental hyperresolved images obtained using an optically addressable parallel-aligned nematic LCD with two zone Toraldo type phase-only filters. The images are compared with theoretical predictions.

  2. Isomorphs in the phase diagram of a model liquid without inverse power law repulsion

    DEFF Research Database (Denmark)

    Veldhorst, Arnold Adriaan; Bøhling, Lasse; Dyre, J. C.;

    2012-01-01

    It is demonstrated by molecular dynamics simulations that liquids interacting via the Buckingham potential are strongly correlating, i.e., have regions of their phase diagram where constant-volume equilibrium fluctuations in the virial and potential energy are strongly correlated. A binary...... Buckingham liquid is cooled to a viscous phase and shown to have isomorphs, which are curves in the phase diagram along which structure and dynamics in appropriate units are invariant to a good approximation. To test this, the radial distribution function, and both the incoherent and coherent intermediate...

  3. Liquid-phase turbulence measurements in air-water two-phase flows over a wide range of void fractions

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xinquan [Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, The Ohio State University, 201 W. 19th Ave., Columbus, OH 43210 (United States); Sun, Xiaodong, E-mail: sun.200@osu.edu [Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, The Ohio State University, 201 W. 19th Ave., Columbus, OH 43210 (United States); Liu, Yang [Nuclear Engineering Program, Department of Mechanical Engineering, Virginia Tech, 635 Prices Fork Road, Blacksburg, VA 24061 (United States)

    2016-12-15

    This paper focuses on liquid-phase turbulence measurements in air-water two-phase flows over a wide range of void fractions and flow regimes, spanning from bubbly, cap-bubbly, slug, to churn-turbulent flows. The measurements have been conducted in two test facilities, the first one with a circular test section and the second one with a rectangular test section. A particle image velocimetry-planar laser-induced fluorescence (PIV-PLIF) system was used to acquire local liquid-phase turbulence information, including the time-averaged velocity and velocity fluctuations in the streamwise and spanwise directions, and Reynolds stress. An optical phase separation method using fluorescent particles and optical filtration technique was adopted to extract the liquid-phase velocity information. An image pre-processing scheme was imposed on the raw PIV images acquired to remove noise due to the presence of bubble residuals and optically distorted particles in the raw PIV images. Four-sensor conductivity probes and high-speed images were also used to acquire the gas-phase information, which was aimed to understand the flow interfacial structure. The highest area-averaged void fraction covered in the measurements for the circular and rectangular test sections was about 40%.

  4. Induction of Ring-Shaped Calcium Oxalate Patterns by Boundaries between Liquid Expanded Phase and Liquid Condensed Phase in Langmuir-Blodgett Film

    Institute of Scientific and Technical Information of China (English)

    WAN Mu-Hua; ZHANG Sheng; ZHENG Hui; OUYANG Jian-Ming

    2008-01-01

    The formation of calcium oxalate kidney stones was related to injuries of renal epithelial membranes.The liquid condensed(LC)domains in Langmuir-Blodgett(LB)film of dipalmitoylphosphatidylcholine(DPPC)were used as a model system to induce crystal growth of urinary mineral calcium oxalate monohydrate(COM).The circular defective boundaries between the LC and liquid expanded(LE)phases of the DPPC monolayer could provide much more nucleating sites for crystallization of COM crystals.It induced ring-shaped or solid circular patterns of COM crystals on hydrophobic quartz substrates depending on the crystallization time.

  5. Phase equilibria and liquid phase epitaxy growth of PbSnSeTe lattice matched to PbSe

    Science.gov (United States)

    Mccann, Patrick J.; Fonstad, Clifton G.; Fuchs, Jacob; Feit, Ze'ev

    1987-01-01

    The necessary phase diagram data for growing lattice-matched layers of PbSnSeTe on PbSe are presented. Solid compounds of Pb(1-x)Sn(x)Se(1-y)Te(y) lattice-matched to PbSe were grown from liquid melts consisting of (Pb/1-x/Sn/x/)(1-z)(Se/1-y/Te/y/)(z); phase equilibria data were determined together with liquidus data for values of x(liquid) from 0 to 40 percent and y(liquid) from 0 to 40 percent for temperatures between 450 and 540 C. It was found that relatively large amounts of Te must be added to the melt to achieve lattice matching because of its low segregation coefficient relative to Se. A significant lattice-pulling effect was discovered for the 5-percent Sn case, and a similar effect is expected for the 10- and 20-percent Sn cases.

  6. Shadow wave-function variational calculations of crystalline and liquid phases of 4He

    Science.gov (United States)

    Vitiello, S. A.; Runge, K. J.; Chester, G. V.; Kalos, M. H.

    1990-07-01

    A new class of variational wave functions for boson systems, shadow wave functions, is used to investigate the properties of solid and liquid 4He. The wave function is translationally invariant and symmetric under particle interchange. In principle, the calculations for the crystalline phase do not require the use of any auxiliary lattice. Using the Metropolis Monte Carlo algorithm, we show that the additional variational degrees of freedom in the wave function lower the energy significantly. This wave function also allows the crystalization of an equilibrated liquid phase when a crystalline seed is used. The pair correlation function and structure factor S(k) are determined in the liquid phase. The condensate fraction is calculated as well. Results are given for the single-particle distribution function around the lattice positions in the solid phase.

  7. Optimized determination of trace jet fuel volatile organic compounds in human blood using in-field liquid-liquid extraction with subsequent laboratory gas chromatographic-mass spectrometric analysis and on-column large-volume injection.

    Science.gov (United States)

    Liu, S; Pleil, J D

    2001-03-05

    A practical and sensitive method to assess volatile organic compounds (VOCs) from JP-8 jet fuel in human whole blood was developed by modifying previously established liquid-liquid extraction procedures, optimizing extraction times, solvent volume, specific sample processing techniques, and a new on-column large-volume injection method for GC-MS analysis. With the optimized methods, the extraction efficiency was improved by 4.3 to 20.1 times and the detection sensitivity increased up to 660 times over the standard method. Typical detection limits in the parts-per-trillion (ppt) level range were achieved for all monitored JP-8 constituents; this is sufficient for assessing human fuels exposures at trace environmental levels as well as occupational exposure levels. The sample extractions are performed in the field and only solvent extracts need to be shipped to the laboratory. The method is implemented with standard biological laboratory equipment and a modest bench-top GC-MS system.

  8. Poly(L-lactic acid)-modified silica stationary phase for reversed-phase and hydrophilic interaction liquid chromatography.

    Science.gov (United States)

    Ohyama, Kaname; Takasago, Shizuka; Kishikawa, Naoya; Kuroda, Naotaka

    2015-03-01

    Poly(L-lactic acid) is a linear aliphatic thermoplastic polyester that can be produced from renewable resources. A poly(L-lactic acid)-modified silica stationary phase was newly prepared by amide bond reaction between amino groups on aminopropyl silica and carboxylic acid groups at the end of the poly(L-lactic acid) chain. The poly(L-lactic acid)-silica column was characterized in reversed-phase liquid chromatography and hydrophilic interaction liquid chromatography with the use of different mobile phase compositions. The poly(L-lactic acid)-silica column was found to work in both modes, and the retention of test compounds depending on acetonitrile content exhibited "U-shaped" curves, which was an indicator of reversed-phase liquid chromatography/hydrophilic interaction liquid chromatography mixed-mode retention behavior. In addition, carbonyl groups included into the poly(L-lactic acid) backbone work as an electron-accepting group toward a polycyclic aromatic hydrocarbon and provide π-π interactions.

  9. Purification of cadmium by selective volatilization in vacuum in presence of oxide phase on its melt

    Indian Academy of Sciences (India)

    N R Munirathnam; K Srinivasa Rao; T L Prakash

    2012-04-01

    Purification of cadmium in the presence of a thin (∼0.001 mm) oxide layer on the surface of the molten metal was carried out using a simple system designed and fabricated locally. The analytical results revealed that the distillation through oxide layer gave better separation for Co, Ni, Cu, Zn, Ag, Sn, Hg and Tl, when compared to the distillation without oxide layer. This was attributed due to the impurity metal oxide phases formation on the surface of the molten metal. The influence of oxygen flow time on the distillation rate of cadmium was established. There was no excess oxygen (O) retained in the distillate after two consecutive vacuum distillations through oxide route. The experiments were conducted at the level of nearly 1.5 kg a batch to study the impurities behaviour due to upscaling. The detailed chemical analysis of 58 impurity elements in Cd in presence and absence of oxide layer was carried out by glow discharge mass spectrometry (GDMS).

  10. Gas holdup in a reciprocating plate bioreactor: Non-Newtonian - liquid phase

    Directory of Open Access Journals (Sweden)

    Naseva Olivera S.

    2002-01-01

    Full Text Available The gas holdup was studied in non-newtonian liquids in a gas-liquid and gas-liquid-solid reciprocating plate bioreactor. Aqueous solutions of carboxy methyl cellulose (CMC; Lucel, Lučane, Yugoslavia of different degrees of polymerization (PP 200 and PP 1000 and concentration (0,5 and 1%, polypropylene spheres (diameter 8.3 mm; fraction of spheres: 3.8 and 6.6% by volume and air were used as the liquid, solid and gas phase. The gas holdup was found to be dependent on the vibration rate, the superficial gas velocity, volume fraction of solid particles and Theological properties of the liquid ohase. Both in the gas-liquid and gas-liquid-solid systems studied, the gas holdup increased with increasing vibration rate and gas flow rate. The gas holdup was higher in three-phase systems than in two-phase ones under otter operating conditions being the same. Generally the gas holdup increased with increasing the volume fraction of solid particles, due to the dispersion action of the solid particles, and decreased with increasing non-Newtonian behaviour (decreasing flow index i.e. with increasing degree of polymerization and solution concentration of CMC applied, as a result of gas bubble coalescence.

  11. Phase separation in dense glassy liquids: effect of quenching protocols

    Science.gov (United States)

    Chaudhuri, Pinaki; Horbach, Jürgen

    2016-08-01

    Extensive molecular dynamics simulations are used to investigate the phase separation kinetics in a glass-forming binary Lennard-Jones mixture. The focus is on the two-phase region at low temperatures (i.e. below the glass transition line), where coexistence between a low-density gas with a metastable amorphous solid, i.e. a glass occurs. Two different quench paths are chosen to get into the two-phase region starting from a structurally homogeneous state, one along which temperature is lowered at a fixed density, and in the other case, the volume is expanded to reach lower densities at fixed temperatures. Both paths are explored by tuning the rates of cooling or expansion, respectively. We analyze thermodynamic and structural properties of the phase-separating systems, in particular with respect to differences in the morphologies that are obtained from the different quench protocols.

  12. Study of phase separation using liquid-gas model of lattice-gas cellular automata

    Energy Technology Data Exchange (ETDEWEB)

    Ebihara, Kenichi; Watanabe, Tadashi; Kaburaki, Hideo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-07-01

    This report describes the study of phase separation by the liquid gas model of lattice gas cellular automata. The lattice gas cellular automaton is one model for simulating fluid phenomena which was proposed by Frisch, Hasslacher and Pomeau in 1986. In 1990, Appert and Zaleski added a new long-range interaction to lattice gas cellular automata to construct a model, the liquid-gas model, which could simulate phase separation using lattice-gas cellular automata. Gerits et al formulated the liquid-gas model mathematically using the theory of statistical dynamics in 1993 and explained the mechanism of phase separation in the liquid-gas model using the equation of state. At first this report explains the FHP model of lattice gas cellular automata and derives fluid dynamics equations such as the equation of continuity and the Navier-Stokes equation. Then the equation of state for the liquid-gas model which was derived by Gerits et al is modified by adding the interactions which were proposed by Appert but not considered by Gerits et al. The modified equation of state is verified by the computer simulation using the liquid gas model. The relation between phase separation and the equation of state is discussed. (author)

  13. Preparation and chromatographic evaluation of a newly designed steviol glycoside modified-silica stationary phase in hydrophilic interaction liquid chromatography and reversed phase liquid chromatography.

    Science.gov (United States)

    Liang, Tu; Fu, Qing; Shen, Aijin; Wang, Hui; Jin, Yu; Xin, Huaxia; Ke, Yanxiong; Guo, Zhimou; Liang, Xinmiao

    2015-04-03

    A diterpene glycoside compound, rebaudioside A (commonly abbreviated as RA), was immobilized onto porous silica surface through "thiol-ene" click chemistry strategy. The successful immobilization of the RA on the silica support was confirmed by FT-IR and elemental analysis. Chromatographic characteristics of the new stationary phase, named Click TE-RA, were evaluated by a set of diverse analytes such as carbohydrates, nucleosides, and organic acids in hydrophilic interaction liquid chromatography (HILIC) mode. The effects of water content, buffer pH and concentration were investigated and a typical HILIC retention feature of Click TE-RA was observed at high organic modifier content. The Click TE-RA stationary phase was further studied by a series of glycoside compounds. Tunable retention mechanisms from hydrophilic to hydrophobic interactions were observed. Separation of very polar compounds including oligosaccharides, nucleic acid bases and nucleosides using Click TE-RA in HILIC mode was successfully accomplished. In addition, separation of saponins both in HILIC and reversed-phase liquid chromatography (RPLC) modes was performed, demonstrating the presence of orthogonality between two different modes on Click TE-RA column. The multiple interactions induced by polar sugar group and hydrophobic aglycone group allowed this Click TE-RA to serve as a multi-mode stationary phase in two-dimensional liquid chromatography.

  14. Universality of Holographic Phase Transitions and Holographic Quantum Liquids

    CERN Document Server

    Benincasa, Paolo

    2009-01-01

    We explore the phase structure for defect theories in full generality using the gauge/gravity correspondence. On the gravity side, the systems are constructed by introducing M (probe) D(p+4-2k)-branes in a background generated by N Dp-branes to obtain a codimension-k intersection. The dual gauge theory is a U(N) Supersymmetric Yang-Mills theory on a (1+p-k)-dimensional defect with both adjoint and fundamental degrees of freedom. We focus on the phase structure in the chemical potential versus temperature plane. We observe the existence of two universality classes for holographic gauge theories, which are identified by the order of the phase transition in the interior of the chemical potential/temperature plane. Specifically, all the sensible systems with no defect show a third order phase transition. Gauge theories on a defect with (p-1)-spatial directions are instead characterised by a second order phase transition. One can therefore state that the order of this phase transition is intimately related to the ...

  15. Liquid-Gas Phase Transition for Asymmetric Nuclear Matter in the Zimanyi-Moszkowski Model

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xu-Ming; QIAN Wei-Liang; SU Ru-Keng

    2004-01-01

    By using the improved Zimanyi-Moszkowski (ZM) model including the freedom of nucleons, σ mesons, ω mesons and ρ mesons, we investigate the liquid-gas phase transition for asymmetric nuclear matter. It is found that the phase transition for asymmetric nuclear matter in the improved ZM model with the isospin vector ρ meson degree of freedom is well defined. The binodal surface, which is essential in the study of the phase transition process, is addressed.

  16. Hydroxypropyl Cellulose Based Non-Volatile Gel Polymer Electrolytes for Dye-Sensitized Solar Cell Applications using 1-methyl-3-propylimidazolium iodide ionic liquid

    Science.gov (United States)

    Khanmirzaei, Mohammad Hassan; Ramesh, S.; Ramesh, K.

    2015-12-01

    Gel polymer electrolytes using imidazolium based ionic liquids have attracted much attention in dye-sensitized solar cell applications. Hydroxypropyl cellulose (HPC), sodium iodide (NaI), 1-methyl-3-propylimidazolium iodide (MPII) as ionic liquid (IL), ethylene carbonate (EC) and propylene carbonate (PC) are used for preparation of non-volatile gel polymer electrolyte (GPE) system (HPC:EC:PC:NaI:MPII) for dye-sensitized solar cell (DSSC) applications. The highest ionic conductivity of 7.37 × 10-3 S cm-1 is achieved after introducing 100% of MPII with respect to the weight of HPC. Temperature-dependent ionic conductivity of gel polymer electrolytes is studied in this work. XRD patterns of gel polymer electrolytes are studied to confirm complexation between HPC polymer, NaI and MPII. Thermal behavior of the GPEs is studied using simultaneous thermal analyzer (STA) and differential scanning calorimetry (DSC). DSSCs are fabricated using gel polymer electrolytes and J-V centeracteristics of fabricated dye sensitized solar cells were analyzed. The gel polymer electrolyte with 100 wt.% of MPII ionic liquid shows the best performance and energy conversion efficiency of 5.79%, with short-circuit current density, open-circuit voltage and fill factor of 13.73 mA cm-2, 610 mV and 69.1%, respectively.

  17. Hydroxypropyl Cellulose Based Non-Volatile Gel Polymer Electrolytes for Dye-Sensitized Solar Cell Applications using 1-methyl-3-propylimidazolium iodide ionic liquid.

    Science.gov (United States)

    Khanmirzaei, Mohammad Hassan; Ramesh, S; Ramesh, K

    2015-12-11

    Gel polymer electrolytes using imidazolium based ionic liquids have attracted much attention in dye-sensitized solar cell applications. Hydroxypropyl cellulose (HPC), sodium iodide (NaI), 1-methyl-3-propylimidazolium iodide (MPII) as ionic liquid (IL), ethylene carbonate (EC) and propylene carbonate (PC) are used for preparation of non-volatile gel polymer electrolyte (GPE) system (HPC:EC:PC:NaI:MPII) for dye-sensitized solar cell (DSSC) applications. The highest ionic conductivity of 7.37 × 10(-3) S cm(-1) is achieved after introducing 100% of MPII with respect to the weight of HPC. Temperature-dependent ionic conductivity of gel polymer electrolytes is studied in this work. XRD patterns of gel polymer electrolytes are studied to confirm complexation between HPC polymer, NaI and MPII. Thermal behavior of the GPEs is studied using simultaneous thermal analyzer (STA) and differential scanning calorimetry (DSC). DSSCs are fabricated using gel polymer electrolytes and J-V centeracteristics of fabricated dye sensitized solar cells were analyzed. The gel polymer electrolyte with 100 wt.% of MPII ionic liquid shows the best performance and energy conversion efficiency of 5.79%, with short-circuit current density, open-circuit voltage and fill factor of 13.73 mA cm(-2), 610 mV and 69.1%, respectively.

  18. Liquid-Phase Deposition of CIS Thin Layers: Final Report, February 2003--July 2005

    Energy Technology Data Exchange (ETDEWEB)

    Ernst, F.; Pirouz, P.

    2006-02-01

    The goal of this project was to fabricate single-phase CIS (a-Cu-In-Se, stoichiometric composition: CuInSe2) thin films for photovoltaic applications from a liquid phase - a Cu-In-Se melt of appropriate composition. This approach of liquid-phase deposition (LPD) is based on the new phase diagram we have established for Cu-In-Se, the first complete equilibrium phase diagram of this system. The liquidus projection exhibits four composition fields in which the primary solid phase, i.e., the first solid material that forms on cooling down from an entirely liquid state, is a-CuInSe2. Remarkably, none of the four composition fields is anywhere near the stoichiometric composition (CuInSe2) of a-CuInSe2. The results demonstrate that the proposed technique is indeed capable of producing films with a particularly large grain size and a correspondingly low density of grain boundaries. To obtain films sufficiently thin for solar cell applications and with a sufficiently smooth surface, it is advantageous to employ a sliding boat mechanism. Future work on liquid-phase deposition of CIS should focus on the interaction between the melt and the substrate surface, the resulting CIS interfaces, the surface morphology of the LPD-grown films, and, of course, the electronic properties of the material.

  19. Phase separation in polymer solutions. I. Liquid-liquid phase separation of PPO poly (2, 6-dimethyl 1, 4-phenylene oxide) in binary mixtures with toluene and ternary mixtures with toluene and ethyl alcohol

    NARCIS (Netherlands)

    Emmerik, van P.T.; Smolders, C.A.

    1972-01-01

    In the system poly(2, 6-dimethy1-1, 4-phenylene oxide) (PPO)-toluene three phase separation lines can be detected: the melting point curve, the cloud point curve, and the spinodial. Because crystallization of PPO occurs very slowly, a phase transition will always be initiated by liquid-liquid phase

  20. Phase separation in polymer solutions. I. Liquid-liquid phase separation of PPO poly (2, 6-dimethyl 1, 4-phenylene oxide) in binary mixtures with toluene and ternary mixtures with toluene and ethyl alcohol

    NARCIS (Netherlands)

    van Emmerik, P.T.; Smolders, C.A.

    1972-01-01

    In the system poly(2, 6-dimethy1-1, 4-phenylene oxide) (PPO)-toluene three phase separation lines can be detected: the melting point curve, the cloud point curve, and the spinodial. Because crystallization of PPO occurs very slowly, a phase transition will always be initiated by liquid-liquid phase

  1. Mass Transfer in a closed stirred gas/liquid contactor: Part 2: The liquid phase mass transfer coefficient kL

    NARCIS (Netherlands)

    Koetsier, W.T.; Thoenes, D.

    1973-01-01

    The liquid phase mass transfer coefficient kL for the absorption of oxygen in tap water and in ionic solutions has been calculated from the quotien It is concluded that the liquid phase mass transfer coefficient is roughly proportional to the stirrer speed. The gas fraction e apparently has little

  2. Liquid-liquid phase separation by nucleation and growth in solutions of poly(2,6 dimethyl-1,4 phenylene oxide) in toluene

    NARCIS (Netherlands)

    Emmerik, van P.T.; Smolders, C.A.

    1973-01-01

    In solutions of poly(2,6 dimethyl-1,4 phenylene oxide) in toluene, the nucleation of the newly formed phase during liquid-liquid phase separation takes place after induction periods which vary between several minutes (at temperatures close to the spinodal) and several hours (at temperatures close to

  3. The [BMI][Tf2N] ionic liquid/water binary system: a molecular dynamics study of phase separation and of the liquid-liquid interface.

    Science.gov (United States)

    Sieffert, N; Wipff, G

    2006-07-01

    We report molecular dynamics (MD) simulations of the aqueous interface of the hydrophobic [BMI][Tf2N] ionic liquid (IL), composed of 1-butyl-3-methylimidazolium cations (BMI+) and bis(trifluoromethylsulfonyl)imide anions (Tf2N-). The questions of water/IL phase separation and properties of the neat interface are addressed, comparing different liquid models (TIP3P vs TIP5P water and +1.0/-1.0 vs +0.9/-0.9 charged IL ions), the Ewald vs the reaction field treatments of the long range electrostatics, and different starting conditions. With the different models, the "randomly" mixed liquids separate much more slowly (in 20 to 40 ns) than classical water-oil mixtures do (typically, in less than 1 ns), finally leading to distinct nanoscopic phases separated by an interface, as in simulations which started with a preformed interface, but the IL phase is more humid. The final state of water in the IL thus depends on the protocol and relates to IL heterogeneities and viscosity. Water mainly fluctuates in hydrophilic basins (rich in O(Tf2N) and aromatic CH(BMI) groups), separated by more hydrophobic domains (rich in CF3(Tf2N) and alkyl(BMI) groups), in the form of monomers and dimers in the weakly humid IL phase, and as higher aggregates when the IL phase is more humid. There is more water in the IL than IL in water, to different extents, depending on the model. The interface is sharper and narrower (approximately 10 A) than with the less hydrophobic [BMI][PF6] IL and is overall neutral, with isotropically oriented molecules, as in the bulk phases. The results allow us to better understand the analogies and differences of aqueous interfaces with hydrophobic (but hygroscopic) ILs, compared to classical organic liquids.

  4. Ecotoxicology of heavy metals: Liquid-phase extraction by nanosorbents

    Science.gov (United States)

    Burakov, A.; Romantsova, I.; Babkin, A.; Neskoromnaya, E.; Kucherova, A.; Kashevich, Z.

    2015-11-01

    The paper considers the problem of extreme toxicity heavy metal compounds dissolved in wastewater and liquid emissions of industrial enterprises to living organisms and environment as a whole. The possibility of increasing extraction efficiency of heavy metal ions by sorption materials was demonstrated. The porous space of the latter was modified by carbon nanotubes (CNTs) during process of the chemical vapour deposition (CVD) of carbon on metal oxide catalysts. The increasing of the sorption capacity (10-30%) and the sorption rate of nanomodified activated carbons in comparison with standard materials in the example of absorption of Co2+ and Ni2+ ions from aqueous solutions was proven.

  5. Removal of volatile to semi-volatile organic contaminants from water using hollow fiber membrane contactors and catalytic destruction of the contaminants in the gas phase

    OpenAIRE

    Tarafder, Shamsul Abedin

    2007-01-01

    Abstract Chlorinated organic compounds and ether compounds are frequently found in groundwater and efficient treatment options are needed. In this study, the efficient transferal of the compounds from the water phase to the gas phase was studied followed by the catalytic treatment of the gas phase. For the removal of the organic contaminants from water, a microporous polypropylene hollow fiber membrane (HFM) module was operated under low strip gas flow to water flow ratios (_< 5:1). Rem...

  6. Visualization and research of gas-liquid two phase flow structures in cylindrical channel

    Directory of Open Access Journals (Sweden)

    Stefański Sebastian

    2017-01-01

    Full Text Available Two-phase flows are commonly found in many industries, especially in systems, where efficient and correct functioning depend on specific values of flow parameters. In thermal engineering and chemical technology the most popular types of two-phase mixture are gas-liquid or liquid-vapour mixtures. Bubbles can create in flow different structures and determine diverse properties of flow (velocity of phase, void fraction, fluctuations of pressure, pipe vibrations, etc.. That type of flow is difficult to observe, especially in liquid-vapour mixture, where vapour is being made by heating the medium. Production of vapour and nucleation process are very complicated issues, which are important part of two-phase flow phenomenon. Gas-liquid flow structures were observed and described with figures, but type of structure depends on many parameters. Authors of this paper made an attempt to simulate gas-liquid flow with air and water. In the paper there was presented specific test stand built to observe two-phase flow structures, methodology of experiment and conditions which were maintained during observation. The paper presents also the structures which were observed and the analysis of results with reference to theoretical models and diagrams available in literature.

  7. In Situ Environmental TEM in Imaging Gas and Liquid Phase Chemical Reactions for Materials Research.

    Science.gov (United States)

    Wu, Jianbo; Shan, Hao; Chen, Wenlong; Gu, Xin; Tao, Peng; Song, Chengyi; Shang, Wen; Deng, Tao

    2016-11-01

    Gas and liquid phase chemical reactions cover a broad range of research areas in materials science and engineering, including the synthesis of nanomaterials and application of nanomaterials, for example, in the areas of sensing, energy storage and conversion, catalysis, and bio-related applications. Environmental transmission electron microscopy (ETEM) provides a unique opportunity for monitoring gas and liquid phase reactions because it enables the observation of those reactions at the ultra-high spatial resolution, which is not achievable through other techniques. Here, the fundamental science and technology developments of gas and liquid phase TEM that facilitate the mechanistic study of the gas and liquid phase chemical reactions are discussed. Combined with other characterization tools integrated in TEM, unprecedented material behaviors and reaction mechanisms are observed through the use of the in situ gas and liquid phase TEM. These observations and also the recent applications in this emerging area are described. The current challenges in the imaging process are also discussed, including the imaging speed, imaging resolution, and data management.

  8. Stationary phase optimized selectivity liquid chromatography: Basic possibilities of serially connected columns using the "PRISMA" principle.

    Science.gov (United States)

    Nyiredy, Sz; Szucs, Zoltán; Szepesy, L

    2007-07-20

    A new procedure (stationary phase optimized selectivity liquid chromatography: SOS-LC) is described for the optimization of the HPLC stationary phase, using serially connected columns and the principle of the "PRISMA" model. The retention factors (k) of the analytes were determined on three different stationary phases. By use of these data the k values were predicted applying theoretically combined stationary phases. These predictions resulted in numerous intermediate theoretical separations from among which only the optimal one was assembled and tested. The overall selectivity of this separation was better than that of any individual base stationary phase. SOS-LC is independent of the mechanism and the scale of separation.

  9. Onset of Convection in Two Liquid Layers with Phase Change

    Energy Technology Data Exchange (ETDEWEB)

    McFadden, G B; Coriell, S R; Gurski, K F; Cotrell, D L

    2006-09-14

    We perform linear stability calculations for horizontal fluid bilayers that can undergo a phase transformation, taking into account both buoyancy effects and thermocapillary effects in the presence of a vertical temperature gradient. We compare the familiar case of the stability of two immiscible fluids in a bilayer geometry with the less-studied case that the two fluids represent different phases of a single-component material, e.g., the water-steam system. The two cases differ in their interfacial boundary conditions: the condition that the interface is a material surface is replaced by the continuity of mass flux across the interface, together with an assumption of thermodynamic equilibrium that in the linearized equations represents the Clausius-Clapeyron relation relating the interfacial temperature and pressures. For the two-phase case, we find that the entropy difference between the phases plays a crucial role in determining the stability of the system. For small values of the entropy difference between the phases, the two-phase system can be linearly unstable to either heating from above or below. The instability is due to the Marangoni effect in combination with the effects of buoyancy (for heating from below). For larger values of the entropy difference the two-phase system is unstable only for heating from below, and the Marangoni effect is masked by effects of the entropy difference. To help understand the mechanisms driving the instability on heating from below we have performed both long-wavelength and short-wavelength analyses of the two-phase system. The short-wavelength analysis shows that the instability is driven by a coupling between the flow normal to the interface and the latent heat generation at the interface. The mechanism for the large wavelength instability is more complicated, and the detailed form of the expansion is found to depend on the Crispation and Bond numbers as well as the entropy difference. The two-phase system allows a

  10. Characterization by solid-phase microextraction-gas chromatography of the volatile profile of protected designation of origin Montasio cheese during ripening.

    Science.gov (United States)

    Innocente, N; Munari, M; Biasutti, M

    2013-01-01

    Montasio is a typical protected designation of origin (PDO) Italian semi-hard and semi-cooked cheese produced in northeast Italy from raw or thermized cow's milk. The PDO label implies that the product has distinctive characteristics that are connected to traditional production methods. The aim of this work was to precisely characterize the volatile fraction of this Italian cheese. The volatile profile can be considered a fingerprint because the flavor of a cheese variety is the result of a specific balance between the volatile compounds produced during the ripening process. Analysis of the volatile profile of Montasio cheese was performed by solid-phase microextraction-gas chromatography. Six cheesemaking trials were performed, each in a different dairy located within the Montasio cheese production area. Cheeses were analyzed at 5 stages of ripening (60, 90, 170, 300, and 365 d). Only 11 compounds were identified and measured: 5 fatty acids, 3 alcohols, 2 ketones, and 1 ester. The limited number of volatile compounds measured in the headspace of the Montasio cheese is probably due to the specific making process of this cheese, which affects evolution of the microflora and the biochemical processes of ripening. The total volatile fraction profile progressively increased from 60 to 170 d, after which time it remained almost steady. The most important contributors were found to be ethanol, short-chain fatty acids (C(2) to C(6)), diacetyl, and ethyl hexanoate. Ethanol and short-chain fatty acids increased up to 170 d, diacetyl increased up to 300 d and then declined, and ethyl hexanoate increased until the final stage.

  11. Liquefaction and methanization of solid and liquid coffee wastes by two phase anaerobic digestion process

    Energy Technology Data Exchange (ETDEWEB)

    Houbron, E.; Rustrian, E. [Universidad Veracruzana, Orizaba, Ver. (Mexico). Facultad de Ciencias Quimicas; Larrinaga, A. [Instituto tecnologico de Orizaba, Ver. (Mexico)

    2003-07-01

    This study attempted to investigate the feasibility of volatile fatty acid (VFA) production from coffee pulp hydrolyse, and further to determine the potential of methanization of both the pre-acidified effluent and the coffee wastewater. The experiments were carried out in 2 completely mixed reactors, each one with working volume of 4 litres. Coffee pulp was used as substrate in the acidogenic reactor and different mixtures of pulper and wash-water and pre-acidified effluent in the methanogenic one. The acidogenic and methanogenic reactors were operated at an organic loading rate of 5 COD g.l{sup -1}.d{sup -1} and 0.5 COD g.l{sup -1}.d{sup -1}. The total, soluble and VFA's effluent COD concentrations of the acidogenic reactor present average values of 57.75, 17.00 and 13.92 g.l{sup -1} respectively. Under these experimental conditions, 23% (COD based) of coffee pulp was hydrolysed with a rate of 1.32 gCOD.l{sup -1}.d{sup -1} and the soluble fraction was transformed to VFA's with an acidification efficiency of 82%. Total VFA's concentration reached a value of 13.9 gCOD.l{sup -1}, and acetate, propionate, butyrate and valerate represented 52%, 28%, 9% and 11% respectively of the liquid phase COD. In the methanogenic reactor, COD removal and methanization of fresh coffee wastewater, pre-acidified effluent and both combined occur with an efficiency of 85% to 95% respectively, with a characteristic biogas composition of 80% CH{sub 4} and 20% CO{sub 2}. These results show that a humid coffee 'Beneficio' processing daily 23 tons of cherry coffee (fresh fruit), equipped with a two stage anaerobic digestion process could generate at least 1,886 CH{sub 4} m{sup 3}.d{sup -1}. This represents an increase in methane production by a factor 3 to 5 compared to a 'Beneficio' using anaerobic digestion only for the treatment of its wastewater. (author)

  12. Liquid chromatography/tandem mass spectrometric bioanalysis using normal-phase columns with aqueous/organic mobile phases - a novel approach of eliminating evaporation and reconstitution steps in 96-well SPE.

    Science.gov (United States)

    Naidong, Weng; Shou, Wilson Z; Addison, Thomas; Maleki, Saber; Jiang, Xiangyu

    2002-01-01

    Bioanalytical methods using automated 96-well solid-phase extraction (SPE) and liquid chromatography with electrospray tandem mass spectrometry (LC/MS/MS) are widely used in the pharmaceutical industry. SPE methods typically require manual steps of drying of the eluates and reconstituting of the analytes with a suitable injection solvent possessing elution strength weaker than the mobile phase. In this study, we demonstrated a novel approach of eliminating these two steps in 96-well SPE by using normal-phase LC/MS/MS methods with low aqueous/high organic mobile phases, which consisted of 70-95% organic solvent, 5-30% water, and small amount of volatile acid or buffer. While the commonly used SPE elution solvents (i.e. acetonitrile and methanol) have stronger elution strength than a mobile phase on reversed-phase chromatography, they are weaker elution solvents than a mobile phase for normal-phase LC/MS/MS and therefore can be injected directly. Analytical methods for a range of polar pharmaceutical compounds, namely, omeprazole, metoprolol, fexofenadine, pseudoephedrine as well as rifampin and its metabolite 25-desacetyl-rifampin, in biological fluids, were developed and optimized based on the foregoing principles. As a result of the time saving, a batch of 96 samples could be processed in one hour. These bioanalytical LC/MS/MS methods were validated according to "Guidance for Industry - Bioanalytical Method Validation" recommended by the Food and Drug Administration (FDA) of the United States.

  13. Analytical performance of three commonly used extraction methods for the gas chromatography-mass spectrometry analysis of wine volatile compounds.

    Science.gov (United States)

    Andujar-Ortiz, I; Moreno-Arribas, M V; Martín-Alvarez, P J; Pozo-Bayón, M A

    2009-10-23

    The analytical performance of three extraction procedures based on cold liquid-liquid extraction using dicloromethane (LLE), solid phase extraction (SPE) using a styrene-divinylbenzene copolymer and headspace solid phase microextraction (SPME) using a carboxen-polydimethylsiloxane coated fibre has been evaluated based on the analysis of 30 representative wine volatile compounds. From the comparison of the three procedures, LLE and SPE showed very good linearity covering a wide range of concentrations of wine volatile compounds, low detection limits, high recovery for most of the volatile compounds under study and higher sensitivity compared to the headspace-SPME procedure. The latter showed in general, poor recovery for polar volatile compounds. Despite some drawbacks associated with the LLE and SPE procedures such as the more tedious sampling treatment and the use of organic solvents, the analytical performance of both procedures showed that they are more adequate for the analysis of wine volatiles.

  14. Comparative study between gas phase and liquid phase for the production of DMC from methanol and CO2

    Institute of Scientific and Technical Information of China (English)

    Ahmed Aouissi; Salem S. Al-Deyab

    2012-01-01

    Direct synthesis of dimethyl carbonate (DMC) from methanol and carbon dioxide over Co1.5PW12O40 in liquid and in gas phase is investigated.The synthesized catalyst has been characterized by means of FTIR and XRD.Liquid phase experiment results showed that high pressures are favorable for the synthesis of DMC.However,DMC formation is limited by the reaction with co-produced water.DMC selectivity is more strongly dependent on the temperature than on the pressure of CO2.As for the reactions in gas phase,it has been found that both CH3OH conversion and DMC selectivity decreased with increasing temperature,owing to the decomposition of DMC at high temperatures.High temperatures and more amount of Co1.5PW12O40 catalyst favor the formation of dimethoxymethane (DMM) and methyl formate (MF).

  15. Mantle Volatiles - Distribution and Consequences

    Science.gov (United States)

    Luth, R. W.

    2003-12-01

    Volatiles in the mantle have, for many years, been the subject of intensive study from a number of perspectives. They are of interest because of their potential effects on melting relationships, on transport of major and trace elements, and on the rheological and other physical properties of the mantle. By convention, "volatiles" in this context are constituents that are liquid or gaseous at normal Earth surface conditions. This review will look at the behavior of C-O-H-S-halogen volatiles, beginning with H2O and C-O volatiles.There have been tremendous strides made recently towards understanding how volatiles in general and water in particular is transported and stored in the mantle. This progress is based on research on a number of fronts: studies of mantle-derived samples have provided insight into the nature and occurrence of hydrous phases such as amphibole, mica, and chlorite, and have provided constraints on the capacity of nominally anhydrous minerals (NAMs) such as olivine, pyroxenes, and garnet to contain "water" by a variety of substitution mechanisms. Experimental studies on mantle-derived magmas have provided constraints on volatile contents in their source regions. Other studies have constrained the pressure, temperature, and composition conditions over which hydrous phases are stable in the mantle.Fundamental questions remain about the geochemical cycling of volatiles in the mantle, and between the mantle and the surface. Much attention has focused on the capability of hydrous phases such as amphibole, mica, serpentine, chlorite, and a family of "dense hydrous magnesian silicates" (DHMSs) to act as carriers of water in subducting slabs back into the mantle. It has been clear since the work of Ito et al. (1983) that there is a discrepancy between the amount of volatiles subducted into the mantle and those returned to the surface by arc magmatism. A recent overview of volatile cycling in subduction systems by Bebout (1996) suggests that 5-15% of the H2

  16. Separation of Flue Gas Components by SILP (Supported Ionic Liquid-Phase) Absorbers

    DEFF Research Database (Denmark)

    Thomassen, P.; Kunov-Kruse, Andreas Jonas; Mossin, Susanne L.

    2013-01-01

    -Phase (SILP) absorber materials. The use of solid SILP absorbers with selected ILs were found to significantly improve the absorption capacity and sorption dynamics at low flue gas concentration, thus making the applicability of ILs viable in technical, continuous flow processes for flue gas cleaning......Reversible absorption of the flue gas components CO2, NO, NO2 and SO2 has been tested for different ionic liquids (ILs) at different temperatures and flue gas compositions where porous, high surface area carriers have been applied as supports for the ionic liquids to obtain Supported Ionic Liquid....... The results show that CO2, NO and SO2 can be reversible and selective absorbed using different ILs and that Supported Ionic Liquid-Phase (SILP) absorbers are promising materials for industrial flue gas cleaning. Absorption/desorption dynamics can be tuned by temperature, pressure and gas concentration. © 2012...

  17. Phase behaviour and dynamics in primitive models of molecular ionic liquids

    Directory of Open Access Journals (Sweden)

    G.C. Ganzenmüller

    2011-09-01

    Full Text Available The phase behaviour and dynamics of molecular ionic liquids are studied using primitive models and extensive computer simulations. The models account for size disparity between cation and anion, charge location on the cation, and cation-shape anisotropy, which are all prominent features of important materials such as room-temperature ionic liquids. The vapour-liquid phase diagrams are determined using high-precision Monte Carlo simulations, setting the scene for in-depth studies of ion dynamics in the liquid state. Molecular dynamics simulations are used to explore the structure, single-particle translational and rotational autocorrelation functions, cation orientational autocorrelations, self diffusion, viscosity, and frequency-dependent conductivity. The results reveal some of the molecular-scale mechanisms for charge transport, involving molecular translation, rotation, and association.

  18. Volatilization of zinc and lead in direct recycling of stainless steel making dust

    Institute of Scientific and Technical Information of China (English)

    PENG Ji(彭及); PENG Bing(彭兵); YU Di(余笛); TANG Mo-tang(唐谟堂); J.Lobel; J.A.Kozinski

    2004-01-01

    The volatilization of zinc and lead from the stainless steel making dust pellets in the direct recycling procedure was conducted by using a thermo-gravimetric analyzer and a Tamman furnace in the nitrogen atmosphere respectively. The results show that the temperature has a significant effect on the volatilization rates of zinc and lead,and the carbon content in the pellets has no effect on the volatilization process. The volatilization of zinc is controlled by the chemical reaction between zinc oxide and carbon monoxide, while the volatilization of lead is controlled by the evaporation front liquid phase to the atmosphere. The volatilization of zinc and lead mainly happen at about 1 000 ℃according to non-isothermal experiment.

  19. Bitcoin Piyasalarının Etkinliği, Likiditesi ve Oynaklığı - Efficiency, Liquidity and Volatility of Bitcoin Markets

    Directory of Open Access Journals (Sweden)

    Şahnaz KOÇOĞLU

    2016-06-01

    Full Text Available Bitcoin is a virtual money and a new payment system which is not regulated by a central authority. Bitcoin became popular quickly and gained the ability of affecting the real economy. Being used extensively and seen as an investment tool, Bitcoin created its own market, users and investors. This study aims to shed light on Bitcoin market. To understand what Bitcoin is, the history of Bitcoin was summarized firstly and the Bitcoin system and how the protocol works was explained. Then Efficiency, Liquidity and Volatility of the Bitcoin Markets were analyzed. We concluded that the pricing of Bitcoin is too complicated; and the Bitcoin market is still vulnerable to many risks and speculation.

  20. Controllable Liquid Artificial Dielectric S-Band Phase Shifters

    Science.gov (United States)

    1975-02-01

    Anisotropyr Shape Factor 4Q) Depentlece. on Shape Ratio (a) ... 1 2-7 &Saare of Shape Fac~tor (Q) Depend~ence an Shape Ratio (6).......... 14 2-8 Dope lgfte...51 6-3 Change In A-rmittivity for Two Parlicie Loading D~en~sities of Magnesium Ibt~er. Reade .12.5-X........................... 51 6...PIN diode and the Ferrite phase shifters. Neither the diode nor the ferrite phase shifter have attained very high peak and average puwer handling