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Sample records for dynamic liquid-phase microextraction

  1. 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%.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Extraction and preconcentration of residual solvents in pharmaceuticals using dynamic headspace-liquid phase microextraction and their determination by gas chromatography-flame ionization detection.

    Science.gov (United States)

    Farajzadeh, Mir Ali; Dehghani, Hamideh; Yadeghari, Adeleh; Khoshmaram, Leila

    2017-02-01

    The present study describes a microextraction and determination method for analyzing residual solvents in pharmaceutical products using dynamic headspace-liquid phase microextraction technique followed by gas chromatography-flame ionization detection. In this method dimethyl sulfoxide (μL level) placed into a GC liner-shaped extraction vessel is used as a collection/extraction solvent. Then the liner is exposed to the headspace of a vial containing the sample solution. The effect of different parameters influencing the microextraction procedure including collection/extraction solvent type and its volume, ionic strength, extraction time, extraction temperature and concentration of NaOH solution used in dissolving the studied pharmaceuticals are investigated and optimized. Under the optimum extraction conditions, the method showed wide linear ranges between 0.5 and 5000 mg L(-1) . The other analytical parameters were obtained in the following ranges: enrichment factors 240-327, extraction recoveries 72-98% and limits of detection 0.1-0.8 mg L(-1) in solution and 0.6-3.2 μg g(-1) in solid. Relative standard deviations for the extraction of 100 mg L(-1) of each analyte were obtained in the ranges of 4-7 and 5-8% for intra-day (n = 6) and inter-day (n = 4) respectively. Finally the target analytes were determined in different samples such as erythromycin, azithromycin, cefalexin, amoxicillin and co-amoxiclav by the proposed method.

  7. 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.

  8. 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.

  9. 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...

  10. Automation of static and dynamic non-dispersive liquid phase microextraction. Part 2: Approaches based on impregnated membranes and porous supports.

    Science.gov (United States)

    Alexovič, Michal; Horstkotte, Burkhard; Solich, Petr; Sabo, Ján

    2016-02-11

    A critical overview on automation of modern liquid phase microextraction (LPME) approaches based on the liquid impregnation of porous sorbents and membranes is presented. It is the continuation of part 1, in which non-dispersive LPME techniques based on the use of the extraction phase (EP) in the form of drop, plug, film, or microflow have been surveyed. Compared to the approaches described in part 1, porous materials provide an improved support for the EP. Simultaneously they allow to enlarge its contact surface and to reduce the risk of loss by incident flow or by components of surrounding matrix. Solvent-impregnated membranes or hollow fibres are further ideally suited for analyte extraction with simultaneous or subsequent back-extraction. Their use can therefore improve the procedure robustness and reproducibility as well as it "opens the door" to the new operation modes and fields of application. However, additional work and time are required for membrane replacement and renewed impregnation. Automation of porous support-based and membrane-based approaches plays an important role in the achievement of better reliability, rapidness, and reproducibility compared to manual assays. Automated renewal of the extraction solvent and coupling of sample pretreatment with the detection instrumentation can be named as examples. The different LPME methodologies using impregnated membranes and porous supports for the extraction phase and the different strategies of their automation, and their analytical applications are comprehensively described and discussed in this part. Finally, an outlook on future demands and perspectives of LPME techniques from both parts as a promising area in the field of sample pretreatment is given.

  11. 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.

  12. Liquid phase microextraction for the analysis of trace elements and their speciation

    Science.gov (United States)

    Hu, Bin; He, Man; Chen, Beibei; Xia, Linbo

    2013-08-01

    Trace/ultra-trace elements and their speciation analysis in complex matrices usually require sample preparation procedures to achieve sample clean-up and analyte preconcentration. Sample preparation is often the bottleneck in trace elements and their speciation analysis which has a direct impact on accuracy, precision and limits of detection and is often the rate-determining step of the analytical process. Recent trends in sample preparation include miniaturization, automation, high-throughput performance and reduction in solvent/sample consumption and operation time. Liquid-phase microextraction (LPME) technique as a novel and promising alternative in sample preparation can meet these requirements and has become a very efficient sample preparation technique. This review updates the state of art of LPME for trace elements and their speciation analysis and discusses its promising prospects. The major thrust of the article highlights the applications of LPME including single-drop microextraction (SDME), hollow fiber-liquid phase microextraction (HF-LPME), dispersive liquid liquid microextraction (DLLME) and solidified floating organic drop microextraction (SFODME) to the fields of elemental and their speciation analysis by atomic spectrometry-based methods, especially inductively coupled plasma mass spectrometry. General and specific concepts, different extraction formats and characteristics of LPME are described and compared, along with examples of recent innovations and applications presented to demonstrate its potential for trace elements and their speciation analysis in biological and environmental fields. Moreover, the application potential and an outlook on the combination of LPME and atomic spectrometry-based techniques for inorganic analysis are commentated.

  13. Applications of Liquid-Phase Microextraction in the Sample Preparation of Environmental Solid Samples

    Directory of Open Access Journals (Sweden)

    Helena Prosen

    2014-05-01

    Full Text Available Solvent extraction remains one of the fundamental sample preparation techniques in the analysis of environmental solid samples, but organic solvents are toxic and environmentally harmful, therefore one of the possible greening directions is its miniaturization. The present review covers the relevant research from the field of application of microextraction to the sample preparation of environmental solid samples (soil, sediments, sewage sludge, dust etc. published in the last decade. Several innovative liquid-phase microextraction (LPME techniques that have emerged recently have also been applied as an aid in sample preparation of these samples: single-drop microextraction (SDME, hollow fiber-liquid phase microextraction (HF-LPME, dispersive liquid-liquid microextraction (DLLME. Besides the common organic solvents, surfactants and ionic liquids are also used. However, these techniques have to be combined with another technique to release the analytes from the solid sample into an aqueous solution. In the present review, the published methods were categorized into three groups: LPME in combination with a conventional solvent extraction; LPME in combination with an environmentally friendly extraction; LPME without previous extraction. The applicability of these approaches to the sample preparation for the determination of pollutants in solid environmental samples is discussed, with emphasis on their strengths, weak points and environmental impact.

  14. Liquid phase microextraction for the analysis of trace elements and their speciation

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Bin, E-mail: binhu@whu.edu.cn; He, Man; Chen, Beibei; Xia, Linbo

    2013-08-01

    Trace/ultra-trace elements and their speciation analysis in complex matrices usually require sample preparation procedures to achieve sample clean-up and analyte preconcentration. Sample preparation is often the bottleneck in trace elements and their speciation analysis which has a direct impact on accuracy, precision and limits of detection and is often the rate-determining step of the analytical process. Recent trends in sample preparation include miniaturization, automation, high-throughput performance and reduction in solvent/sample consumption and operation time. Liquid-phase microextraction (LPME) technique as a novel and promising alternative in sample preparation can meet these requirements and has become a very efficient sample preparation technique. This review updates the state of art of LPME for trace elements and their speciation analysis and discusses its promising prospects. The major thrust of the article highlights the applications of LPME including single-drop microextraction (SDME), hollow fiber-liquid phase microextraction (HF-LPME), dispersive liquid liquid microextraction (DLLME) and solidified floating organic drop microextraction (SFODME) to the fields of elemental and their speciation analysis by atomic spectrometry-based methods, especially inductively coupled plasma mass spectrometry. General and specific concepts, different extraction formats and characteristics of LPME are described and compared, along with examples of recent innovations and applications presented to demonstrate its potential for trace elements and their speciation analysis in biological and environmental fields. Moreover, the application potential and an outlook on the combination of LPME and atomic spectrometry-based techniques for inorganic analysis are commentated. - Highlights: • The state of art of LPME for trace elements and their speciation analysis is updated. • Different extraction formats of LPME are described. • The application potential and future

  15. Liquid-phase microextraction for simultaneous chromatographic analysis of three antidepressant drugs in plasma

    Directory of Open Access Journals (Sweden)

    Carlos Eduardo Dobrovolskni Porto

    2012-01-01

    Full Text Available A method using Liquid Phase Microextraction for simultaneous detection of citalopram (CIT, paroxetine (PAR and fluoxetine (FLU, using venlafaxine as internal standard, in plasma by high performance liquid chromatography with fluorescence detection was developed. The linearity was evaluated between 5.0 and 500 ng mL-1 (r > 0.99 and the limit of quantification was 2.0, 3.0 and 5.0 ng mL-1 for CIT, PAR and FLU, respectively. Therefore, it can be applied to therapeutic drug monitoring, pharmacokinetics or bioavailability studies and its advantages are that it necessary relatively inexpensive equipment and sample preparation techniques.

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

    OpenAIRE

    2011-01-01

    Hollow fiber liquid phase micro-extraction (LPME) of linear alkylbenzene sulfonates (LAS) from aqueous samples was studied. Ion pair extraction of C10, C11, C12 and C13 homologues was facilitated with trihexylamine as ion-pairing agent, using di-n-hexylether as solvent for the supported liquid membrane (SLM). Effects of extraction time, acceptor buffer concentration, stirring speed, sample volume, NaCl and humic acids were studied. At 10–50 μg L−1 linear R2-coefficients were 0.99 for C10 and ...

  17. Single-drop liquid phase microextraction accelerated by surface acoustic wave.

    Science.gov (United States)

    Zhang, Anliang; Zha, Yan

    2013-03-01

    A single-drop liquid phase microextraction method is presented, in which surface acoustic wave (SAW) is used for accelerating extraction speed. A pair of interdigital transducers with 27.5 MHz center frequency is fabricated on a 128° yx-LiNbO3 substrate. A radio frequency signal is applied to one of interdigital transducers to excite SAW. Plastic straw is filled with PDMS, leaving 1 mL for holding sample solution. Plastic straw with sample solution droplet is then dipping into extractant, into which SAW is radiated. Mass transportation from sample solution to extractant drop is accelerated due to acoustic streaming, and extraction time is decreased. An ionic liquid and an acid green-25 solution are used for extraction experiments. Results show that the extraction process is almost finished within 2 min, and extraction speed is increased with radio frequency signal power.

  18. Rapid determination of atrazine in environmental water samples by a novel liquid phase microextraction

    Institute of Scientific and Technical Information of China (English)

    Qing Xiang Zhou; Guo Hong Xie; Long Pang

    2008-01-01

    A novel method was described for the rapid determination of atrazine using dispersive liquid phase microextraction incombination with high performance liquid chromatography (HPLC). Possible impact parameters such as sample pH, extraction anddisperser solvents, salting-out effect, and extraction time were investigated. The experimental results indicated that proposedmethod possessed an excellent analytical performance. The linear range, detection limit, and precision (R.S.D.) were 0.1-50 ng mL-1 (R2 = 0.9955), 0.601 ng mL-1 and 6.4%, respectively. The proposed method was validated with the real water samples,and the spiked recoveries were in the range of 69.9-89.8%, respectively. These results indicated that the established method withhigh enrichment factor, short extraction time was an excellent alternative for the routine analysis of atrazine in environmentalsamples.

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

    Directory of Open Access Journals (Sweden)

    Jan Åke Jönsson

    2011-10-01

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

  20. 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.

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

    Science.gov (United States)

    Wang, Mi-Hung; Wang, Shu-Ping

    2012-03-01

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

  2. Liquid phase micro-extraction of linear alkylbenzene sulfonate anionic surfactants in aqueous samples.

    Science.gov (United States)

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

    2011-10-13

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

  3. Liquid phase micro-extraction: Towards the green methodology for ultratrace metals determination in aquatic ecosystems

    Directory of Open Access Journals (Sweden)

    López-López J. A.

    2013-04-01

    Full Text Available Heavy metals are normally found, in natural waters, in very low concentrations. Some of them are essential for life in low level; however, in higher level they are toxic. Therefore, analyzing their bio-available fraction is of main interest. Standard methodology is based in the collection of a number of samples from a water body. Collected samples must be stored, pre-treated and then analyzed. Pre-treatment usually involves pre-concentrating the metal, with the corresponding risk of contamination or loss of analyte. This way, punctual information is obtained from every sampling campaign. As an alternative, passive sampling techniques allow the continuous and coupled sampling-pre-treatment for heavy metals analysis, giving a better approach in the characterization of the studied water body. Liquid phase micro-extraction (LPME is a green analytical alternative for liquid-liquid extraction that promotes a reduction of sample volume, solvent needed and waste generation. Using these systems, polypropylene hollow fibers (HF with pores in their walls can be used. A few micro-liters of organic solvent are supported in the pores. The sample is placed in the outer part of the fiber and a receiving phase is placed in its inner part, allowing continuous liquid extraction of the metal from the sample. Several fibers with different physical features have been employed to analyzed total concentration and bio-availability of some heavy metals (Ag, Ni, Cu in natural water samples. Thanks to fibers configuration, devices for passive sampling based in HF-LPME could be designed. Advantages of this methodology over existing ones are supported because the receiving phase is liquid. As a consequence, retained metals do not need to be eluted from the acceptor prior to instrumental analysis.

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

    Science.gov (United States)

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

    2013-12-04

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

  5. Quantitative Analysis of Piroxicam Using Temperature-Controlled Ionic Liquid Dispersive Liquid Phase Microextraction Followed By Stopped-Flow Injection Spectrofluorimetry

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Ganjali

    2013-07-01

    Full Text Available Background:Piroxicam (PXM belongs to the wide class of non-steroidal anti-inflammatory drugs (NSAIDs. PXM has been widely applied in the treatment of rheumatoid arthritis, gonarthrosis, osteoarthritis, backaches, neuralgia, mialgia. In the presented work, a green and benign sample pretreatment method called temperature-controlled ionic liquid dispersive liquid phase microextraction (TCIL-DLPME was followed with stopped-flow injection spectrofluorimetry (SFIS for quantitation of PXM in pharmaceutical formulations and biological samples.Methods:Temperature-controlled ionic liquid dispersive liquid phase microextraction (TCIL-DLPME was applied as an environmentally friendly sample enrichment method to extract and isolate PXM prior to quantitation. Dispersion of 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim][PF6] ionic liquid (IL through the sample aqueous solution was performed by applying a relatively high temperature. PXM was extracted into the extractor, and after phase separation, PXM in the final solution was determined by stopped-flow injection spectrofluorimetry (SFIS.Results and Major Conclusion:Different factors affecting the designed method such as IL amount, diluting agent, pH and temperature were investigated in details and optimized. The method provided a linear dynamic range of 0.2-150 μg l-1, a limit of detection (LOD of 0.046 μg l-1 and a relative standard deviation (RSD of 3.1%. Furthermore, in order to demonstrate the analytical applicability of the recommended method, it was applied for quantitation of PXM in real samples.

  6. Improvement of Liquid-phase Microextraction Method%分散液相微萃取方法的改进

    Institute of Scientific and Technical Information of China (English)

    林燕玲

    2011-01-01

    本文探讨了一种利用毛细管进行液相微萃取的新方法,对萃取剂体积、乳化剂体积、盐溶液浓度等影响因素进行了考察,并用该方法萃取水溶液的苯甲酸并用气相色谱氢火焰离子化检测器(GC-FID)进行检测,以甲苯作为萃取剂,乙醚作为乳化剂,得到校正曲线的线性r2为0.9951,回收率为101.8%,检出限为0.082g/L。%A new liquid-phase microextraction technique which employs capillary is developed in this dissertation.The benzoic acid water solution was utilized to assess the new liquid-phase microextraction method.After microextraction,the target compounds were separated and determined by the GC-FID.The effects of some extraction parameters such as the volume of solvent,the volume of emulsifier and the salt were studied.The new microextraction method provides a good linearity while toluene and diethyl ether were employed as the extraction solvent and emulsifier,respectively.Studies showed that the r2 for the calibration curve is 0.9954,recovery is 101.8% and LOD is 0.082g/L.

  7. Measurement uncertainty for the determination of amphetamines in urine by liquid-phase microextraction and gas chromatography-mass spectrometry.

    Science.gov (United States)

    Franco de Oliveira, Sarah Carobini Werner de Souza Eller; Yonamine, Mauricio

    2016-08-01

    A gas chromatography-mass spectrometry method for the determination of amphetamines in urine samples by means of liquid-phase microextraction was validated, including calculation of measurement uncertainty. After extraction in the three-phase mode, acceptor phase was withdrawn from the fiber and the residue was derivatized with trifluoroacetic anhydride. The method showed to be very simple, rapid and it required a significantly low amount of organic solvent for extraction. The limits of detection were 10 and 20μg/L for amphetamine and methamphetamine, respectively. The calibration curves were linear over the specified range (20μg/L to 1400μg/L; r(2)>0.99). The method showed to be both precise and accurate and a relative combined uncertainty of 2% was calculated. In order of importance, the factors which were more determinant for the calculation of method uncertainty were: analyte concentration, sample volume, trueness and method precision.

  8. Gas-assisted dispersive liquid-phase microextraction using ionic liquid as extracting solvent for spectrophotometric speciation of copper.

    Science.gov (United States)

    Akhond, Morteza; Absalan, Ghodratollah; Pourshamsi, Tayebe; Ramezani, Amir M

    2016-07-01

    Gas-assisted dispersive liquid-phase microextraction (GA-DLPME) has been developed for preconcentration and spectrophotometric determination of copper ion in different water samples. The ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate and argon gas, respectively, were used as the extracting solvent and disperser. The procedure was based on direct reduction of Cu(II) to Cu(I) by hydroxylamine hydrochloride, followed by extracting Cu(I) into ionic liquid phase by using neocuproine as the chelating agent. Several experimental variables that affected the GA-DLPME efficiency were investigated and optimized. Under the optimum experimental conditions (IL volume, 50µL; pH, 6.0; acetate buffer, 1.5molL(-1); reducing agent concentration, 0.2molL(-1); NC concentration, 120µgmL(-1); Ar gas bubbling time, 6min; argon flow rate, 1Lmin(-1); NaCl concentration, 6% w/w; and centrifugation time, 3min), the calibration graph was linear over the concentration range of 0.30-2.00µgmL(-1) copper ion with a limit of detection of 0.07µgmL(-1). Relative standard deviation for five replicate determinations of 1.0µgmL(-1) copper ion was found to be 3.9%. The developed method was successfully applied to determination of both Cu(I) and Cu(II) species in water samples.

  9. Comparison between solid phase microextraction (SPME) and hollow fiber liquid phase microextraction (HFLPME) for determination of extractables from post-consumer recycled PET into food simulants.

    Science.gov (United States)

    Oliveira, Éder Costa; Echegoyen, Yolanda; Cruz, Sandra Andrea; Nerin, Cristina

    2014-09-01

    Hollow fiber liquid phase microextraction (HFLPME) and solid phase microextraction (SPME) methods for pre-concentration of contaminants (toluene, benzophenone, tetracosane and chloroform) in food simulants were investigated. For HFLPME 1-heptanol, 2-octanone and dibutyl-ether were studied as extracting solvents. Analysis by gas chromatography coupled to mass spectrometry (GC-MS), flame ionization (GC-FID) and electron capture detectors (GC-ECD) were carried out. In addition, the methods were employed to evaluate the safety in use of a PET material after the recycling process (comprising washing, extrusion and solid state polymerization (SSP)) through extractability studies of the contaminants using 10% (v/v) ethanol in deionized water and 3% (w/v) acetic acid in deionized water as food simulants in different conditions: 10 days at 40°C and 2h at 70°C. The HFLPME preconcentration method provided increased sensitivity when compared to the SPME method and allowed to analyze concentration levels below 10 µg surrogate per kg food simulant. The results of the extractability studies showed considerable reductions after the extrusion and SSP processes and indicated the compliance with regulations for using recycled PET in contact with food. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. 超声提取-动态液相微萃取-气相色谱法测定土豆中有机磷农药%GC Determination of Organophosphorous Pesticides in Potato with Ultrasonic Extraction and Dynamic Liquid Phase Micro-extraction

    Institute of Scientific and Technical Information of China (English)

    焦琳娟

    2012-01-01

    Smashed potato sample was extracted ultrasonically with water, the filtrate was treated by dynamic liquid phase micro-extraction (DLPME) using n-octanol as extracting agent, to separate and enrich the 3 organophosphorus pesticides, i. e. , dichloroas, methylparathion and parathion, which were then determined by GC. OV-1701 capillary column was used in GC separation and flame photometric detection was adopted in the determination. Ranges of linearity for the 3 organophosphorous pesticides were same between 2. 0-50. 0μg g-1, with values of detection limit (3S/N) of 0. 20, 0. 46, 0.42μg g-1 for methylparathion, parathion and diehlorovos respectively. Using potato samples as matrixes, values of recovery found by standard addition method were in the range of 90. 6%-101% with RSD's (n=7) in the range of 3.2%-5.6%.%经粉碎后的土豆样品用水超声提取,取滤液以正辛醇为萃取溶剂进行动态液相微萃取处理,对样品中3种有机磷农药敌敌畏、甲基对硫磷和对硫磷进行富集分离。气相色谱法测定时采用OV-1701毛细管色谱柱分离和火焰光度检测器测定。3种农药的线性范围均在2.0~50.0μg·g-1之间,检出限(3S/N)依次为0.20,0.46,0.42μg·g-1。以土豆样品作基体,用标准加入法做回收试验,测得回收率在90.6%~101%之间,相对标准偏差(n=7)在3.2%~5.6%之间。

  11. 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.

  12. [Determination of dichloromethane and trichloromethane residues in ranitidine hydrochloride by headspace liquid phase microextraction coupled with gas chromatography].

    Science.gov (United States)

    Shen, Shuchang; Yun, Dan; Li, Fei

    2009-11-01

    A method for the determination of residual dichloromethane and trichloromethane in ranitidine hydrochloride by headspace liquid phase microextraction coupled with gas chromatography (GC) was developed. A homemade device was used to protect the organic drop. The effects of the nature of extraction solvent, extraction time, extraction temperature and microdrop volume on the extraction efficiency were investigated separately. The optimal experimental conditions were as follows: 2 microL of n-tridecane as extraction solvent, 30 min of extraction time, 60 degrees C of extraction temperature. The correlation coefficients of linear calibration curve were 0.9733 and 0.9724 within the concentration ranges of dichloromethane (1-10 microg/g) and trichloromethane (1-10 microg/g), respectively. The detection limits of dichlormethane and trichloromethane were 0.0273 microg/g and 0.0410 microg/g, respectively, the relative standard deviations were lower than 4.36% and 5.89%, and the recoveries of the method were 93.6%-102% and 98.1% respectively. The method is simple and reliable.

  13. A novel, donor-active solvent-assisted liquid-phase microextraction procedure for spectrometric determination of zinc

    Energy Technology Data Exchange (ETDEWEB)

    Kocurova, Livia; Fatlova, Martina; Bazel, Yaroslav; Serbin, Rastislav; Andruch, Vasil, E-mail: liviamonika.kocurova@gmail.com [Department of Analytical Chemistry, University of P. J. Safarik, Kosice (Slovakia); Balogh, Ioseph S. [Department of Chemistry, College of Nyiregyhaza (Hungary); Simon, Andras [Department of General and Analytical Chemistry, Budapest University of Technology and Economics, Budapest (Hungary); Badida, Miroslav; Rusnak, Radoslav [Department of Environmentalistics, Faculty of Mechanical Engineering, Technical University of Kosice (Slovakia)

    2014-02-15

    Based on the reaction of Zn(II), thiocyanate and 2-[2-(5-dimethylamino-thiophen-2-yl)-vinyl]- 1,3,3-trimethyl-3H-indolium bromide (DTVTI), a donor-active solvent-assisted liquid-phase microextraction procedure followed by spectrophotometric determination of zinc at 570 nm was developed. The optimum experimental conditions were investigated and found to be as follows: concentration of NH{sub 4}SCN 0.02 mol L{sup -1} concentration of DTVTI 4 x 10{sup -5} mol L{sup -1}. Various extraction solvents were studied alone as well as in mixtures with different improvers, and a mixture of toluene as the extraction solvent and tributylphosphate as the donor-active solvent in a 4:1 v/v ratio was selected. The calibration plot was linear up to 2.62 mg L{sup 1} of zinc with limit of detection 0.09 mg L{sup -1}. The developed procedure was applied for zinc determination in dietary supplements. (author)

  14. HPLC determination of ibuprofen, diclofenac and salicylic acid using hollow fiber-based liquid phase microextraction (HF-LPME).

    Science.gov (United States)

    Ramos Payán, María; Bello López, Miguel Angel; Fernández-Torres, Rut; Pérez Bernal, Juan Luis; Callejón Mochón, Manuel

    2009-10-27

    This paper describes an extraction method using a polypropylene membrane supporting dihexyl ether (three-phase hollow fiber-based liquid phase microextraction (HF-LPME)) for the analysis of several pharmaceuticals (salicylic acid (SAC), ibuprofen (IBU) and diclofenac (DIC)) followed by a HPLC determination using a monolithic silica type HPLC column, that allows lower retention times than the usual packed columns with adequate resolution. Detection was realized by means of a coupled in series diode array (DAD) and fluorescence (FLD) detectors. HF-LPME is a relatively new technique employed in analytical chemistry for sample pretreatment which offers more selectivity and sensitivity than any traditional extraction technique. Detection limits by DAD are 12, 53 and 40 ng mL(-1) for salicylic acid, diclofenac and ibuprofen, respectively and by FLD 7 and 2 ng mL(-1) for salicylic acid, and ibuprofen. The method has been successfully applied to their direct determination in human urine and the results obtained demonstrated that could be also applied to the determination of the corresponding metabolites.

  15. Mass transfer resistance in a liquid-phase microextraction employing a single hollow fiber under unsteady-state conditions.

    Science.gov (United States)

    Kumrić, Ksenija R; Vladisavljević, Goran T; Đorđević, Jelena S; Jönsson, Jan Åke; Trtić-Petrović, Tatjana M

    2012-09-01

    In this study, the mass transport resistance in liquid-phase microextraction (LPME) in a single hollow fiber was investigated. A mathematical model has been developed for the determination of the overall mass transfer coefficient based on the acceptor phase in an unsteady state. The overall mass transfer coefficient in LPME in a single hollow fiber has been estimated from time-dependent concentration of extracted analyte in the acceptor phase while maintaining a constant analyte concentration in the donor phase. It can be achieved either using a high volume of donor to acceptor phase ratio or tuning the extraction conditions to obtain a low-enrichment factor, so that the analyte concentration in the sample is not significantly influenced by the mass transfer. Two extraction systems have been used to test experimentally the developed model: the extraction of Lu(III) from a buffer solution and the extraction of three local anesthetics from a buffer or plasma solution. The mass transfer resistance, defined as a reciprocal values of the mass transfer coefficient, was found to be 1.2 × 10(3) cm(-1) min for Lu(III) under optimal conditions and from 1.96 to 3.3 × 10(3) cm(-1) min for the local anesthetics depending on the acceptor pH and the hydrophobicity of the drug.

  16. 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.

  17. Hollow-fiber liquid phase microextraction for lignin pyrolysis acids in aerosol samples and gas chromatography-mass spectrometry analysis.

    Science.gov (United States)

    Hyder, Murtaza; Jönsson, Jan Åke

    2012-08-03

    A method based on three-phase hollow fiber liquid phase microextraction was developed and successfully applied to aerosols for the analysis of lignin pyrolysis acids such as syringic acid, vanillic acid and p-salicylic acid. Important parameters related to extraction process like organic solvent for membrane phase, tri-n-octylphosphine (TOPO) oxide contents in organic solvent, stirring speed, extraction time etc. were optimized. 6-Undecanone with 15% TOPO contents (w/v) was found a suitable solvent for organic liquid membrane, 900 rpm was the optimum stirring speed and time of 4h was found optimum extraction time. Donor phase pH was 1.3 while acceptor phase pH was adjusted to 9.5. The optimized extraction method was used for the extraction of real aerosol samples. Analytes were derivatized using BSTFA containing 1% trimethylsilyl chloride and gas chromatography mass spectrometry was used for analysis. Very low limits of detection in the range 0.2-1.0 ng L(-1) were found, corresponding to 10-50 pg m(-3) of analytes in aerosols. Extraction efficiency obtained ranged 60.3-71.7% and enrichment factors ranged 3015-3585 times. The optimized method was successfully applied to aerosol samples and all of the selected analytes were detected in the analyzed samples. Copyright © 2012 Elsevier B.V. All rights reserved.

  18. 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.

  19. 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.

  20. Determination of partition coefficient and analysis of nitrophenols by three-phase liquid-phase microextraction coupled with capillary electrophoresis.

    Science.gov (United States)

    Sanagi, Mohd Marsin; Miskam, Mazidatulakmam; Wan Ibrahim, Wan Aini; Hermawan, Dadan; Aboul-Enein, Hassan Y

    2010-07-01

    A three-phase hollow fiber liquid-phase microextraction method coupled with CE was developed and used for the determination of partition coefficients and analysis of selected nitrophenols in water samples. The selected nitrophenols were extracted from 14 mL of aqueous solution (donor solution) with the pH adjusted to pH 3 into an organic phase (1-octanol) immobilized in the pores of the hollow fiber and finally backextracted into 40.0 microL of the acceptor phase (NaOH) at pH 12.0 located inside the lumen of the hollow fiber. The extractions were carried out under the following optimum conditions: donor solution, 0.05 M H(3)PO(4), pH 3.0; organic solvent, 1-octanol; acceptor solution, 40 microL of 0.1 M NaOH, pH 12.0; agitation rate, 1050 rpm; extraction time, 15 min. Under optimized conditions, the calibration curves for the analytes were linear in the range of 0.05-0.30 mg/L with r(2)>0.9900 and LODs were in the range of 0.01-0.04 mg/L with RSDs of 1.25-2.32%. Excellent enrichment factors of up to 398-folds were obtained. It was found that the partition coefficient (K(a/d)) values were high for 2-nitrophenol, 3-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol and 2,6-dinitrophenol and that the individual partition coefficients (K(org/d) and K(a/org)) promoted efficient simultaneous extraction from the donor through the organic phase and further into the acceptor phase. The developed method was successfully applied for the analysis of water samples.

  1. Ion-pair hollow-fiber liquid-phase microextraction of the quaternary ammonium surfactant dicocodimethylammonium chloride.

    Science.gov (United States)

    Hultgren, Sofie; Larsson, Niklas; Nilsson, Bo F; Jönsson, Jan Ake

    2009-02-01

    A two-phase hollow-fiber (HF) liquid-phase microextraction (LPME) method was developed for determination of a quaternary ammonium compound surfactant, dicocodimethylammonium chloride, in aqueous samples. The porous HF was fixed on a metal rod support and was impregnated with approximately 6.6 microL of organic extractant, which was immobilized in the HF pores. Surfactant extraction was facilitated by addition of carboxylic acid to the sample forming neutral ion pairs with the quaternary ammonium compound. After extraction, the analyte was transferred from the organic extractant in the fiber pores by dissolving the 1-octanol into 100 microL methanol. The methanol extract was analyzed by liquid chromatography-mass spectrometry. The method was optimized (with optimized parameters in brackets) with regard to type of organic extractant (1-octanol), fiber length (2 cm), choice and concentration of anionic carrier (600 microg L(-1) octanoate), procedure of transfer to methanol (15-min sonication), sample volume (250 mL), extraction time (17 h), pH (10), and ionic strength (50 mM carbonate). Aspects influencing repeatability in LPME of (quaternary ammonium) surfactants are discussed. The enrichment factor achieved in 250-mL carbonate buffer was around 400. Due to matrix effects, the enrichment factors achieved when industrial process water was analyzed were 120 or about 30% of that in carbonate buffer. Detection limits of 0.3 microg L(-1) in carbonate buffer and 0.9 microg L(-1) in industrial process water were obtained. If the studied compound is seen as a model substance representing quaternary dialkylated dimethylated ammonium surfactants in general, the developed method may be applied to other quaternary ammonium surfactants.

  2. Application of hollow fiber-supported liquid-phase microextraction coupled with HPLC for the determination of guaifenesin enantiomer-protein binding.

    Science.gov (United States)

    Hatami, Mehdi; Farhadi, Khalil

    2012-07-01

    A hollow fiber liquid-phase microextraction technique coupled with high-performance liquid chromatography with fluorescence detection was employed for determination and evaluation of the binding characteristics of drugs to bovine serum albumin (BSA). Enantiomers of guaifenesin (an expectorant drug) were investigated as a model system. After optimization of some influencing parameters on microextraction, the proposed method was used for calculation of the target drug distribution coefficient between n-octanol and the buffer solution as well as study of drug-BSA binding in physiological conditions. The developed method shows a new, improved and simple procedure for determination of free drug concentration in biological fluids and the extent of drug-protein binding. Copyright © 2011 John Wiley & Sons, Ltd.

  3. Ion pair-based liquid-phase microextraction combined with cuvetteless UV-vis micro-spectrophotometry as a miniaturized assay for monitoring ammonia in waters.

    Science.gov (United States)

    Senra-Ferreiro, Sonia; Pena-Pereira, Francisco; Costas-Mora, Isabel; Romero, Vanesa; Lavilla, Isela; Bendicho, Carlos

    2011-09-15

    A miniaturized method based on liquid-phase microextraction (LPME) in combination with microvolume UV-vis spectrophotometry for monitoring ammonia in waters is proposed. The methodology is based on the extraction of the ion pair formed between the blue indophenol obtained according to the Berthelot reaction and a quaternary ammonium salt into a microvolume of organic solvent. Experimental parameters affecting the LPME performance such as type and concentration of the quaternary ammonium ion salt required to form the ion pair, type and volume of extractant solvent, effect of disperser solvent, ionic strength and extraction time, were optimized. A detection limit of 5.0 μg L(-1) ammonia and an enrichment factor of 30 can be attained after a microextraction time of 4 min. The repeatability, expressed as relative standard deviation, was 7.6% (n=7). The proposed method can be successfully applied to the determination of trace amounts of ammonia in several environmental water samples.

  4. Selective determination of inorganic cobalt in nutritional supplements by ultrasound-assisted temperature-controlled ionic liquid dispersive liquid phase microextraction and electrothermal atomic absorption spectrometry.

    Science.gov (United States)

    Berton, Paula; Martinis, Estefanía M; Martinez, Luis D; Wuilloud, Rodolfo G

    2012-02-03

    In the present work, a simple and rapid analytical method based on application of ionic liquids (ILs) for inorganic Co(II) species (iCo) microextraction in a variety of nutrient supplements was developed. Inorganic Co was initially chelated with 1-nitroso-2-naphtol (1N2N) reagent followed by a modern technique named ultrasound-assisted temperature-controlled ionic liquid dispersive liquid phase microextraction (USA-TILDLME). The extraction was performed with 1-hexyl-3-methylimidazolium hexafluorophosphate [C(6)mim][PF(6)] with the aid of ultrasound to improve iCo recovery. Finally, the iCo-enriched IL phase was solubilized in methanol and directly injected into an electrothermal atomic absorption spectrometer (ETAAS). Several parameters that could influence iCo microextraction and detection were carefully studied. Since the main difficulty in these samples is caused by high concentrations of potential interfering ions, different approaches were evaluated to eliminate interferences. The limit of detection (LOD) was 5.4 ng L(-1), while the relative standard deviation (RSD) was 4.7% (at 0.5 μg L(-1) Co level and n=10), calculated from the peak height of absorbance signals. Selective microextraction of iCo species was achieved only by controlling the pH value during the procedure. The method was thus successfully applied for determination of iCo species in nutritional supplements. Copyright © 2011 Elsevier B.V. All rights reserved.

  5. On-line liquid phase micro-extraction based on drop-in-plug sequential injection lab-at-valve platform for metal determination

    Energy Technology Data Exchange (ETDEWEB)

    Mitani, Constantina [Laboratory of Analytical Chemistry, Department of Chemistry, Aristotle University, Thessaloniki 54124 (Greece); Anthemidis, Aristidis N., E-mail: anthemid@chem.auth.gr [Laboratory of Analytical Chemistry, Department of Chemistry, Aristotle University, Thessaloniki 54124 (Greece)

    2013-04-10

    Highlights: ► Drop-in-plug micro-extraction based on SI-LAV platform for metal preconcentration. ► Automatic liquid phase micro-extraction coupled with FAAS. ► Organic solvents with density higher than water are used. ► Lead determination in environmental water and urine samples. -- Abstract: A novel automatic on-line liquid phase micro-extraction method based on drop-in-plug sequential injection lab-at-valve (LAV) platform was proposed for metal preconcentration and determination. A flow-through micro-extraction chamber mounted at the selection valve was adopted without the need of sophisticated lab-on-valve components. Coupled to flame atomic absorption spectrometry (FAAS), the potential of this lab-at-valve scheme is demonstrated for trace lead determination in environmental and biological water samples. A hydrophobic complex of lead with ammonium pyrrolidine dithiocarbamate (APDC) was formed on-line and subsequently extracted into an 80 μL plug of chloroform. The extraction procedure was performed by forming micro-droplets of aqueous phase into the plug of the extractant. All critical parameters that affect the efficiency of the system were studied and optimized. The proposed method offered good performance characteristics and high preconcentration ratios. For 10 mL sample consumption an enhancement factor of 125 was obtained. The detection limit was 1.8 μg L{sup −1} and the precision expressed as relative standard deviation (RSD) at 50.0 μg L{sup −1} of lead was 2.9%. The proposed method was evaluated by analyzing certified reference materials and applied for lead determination in natural waters and urine samples.

  6. Hybrid flow analyzer for automatic hollow-fiber-assisted ionic liquid-based liquid-phase microextraction with in-line membrane regeneration.

    Science.gov (United States)

    Nitiyanontakit, Sira; Varanusupakul, Pakorn; Miró, Manuel

    2013-04-01

    The proof-of-concept of a new methodology for in-line hollow-fiber (HF)-assisted three-phase liquid-phase microextraction (LPME) allowing for handling of the feed and acceptor aqueous solutions and of minute volumes of the organic extracting phase in a programmable flow mode is reported in this paper. The flow analyzer fosters in-line anchoring of ionic-liquid-laden extracting solution (10 % (v/v) methyltrioctyl ammonium chloride in kerosene) in the pores of a single-strand microporous polypropylene HF, and regeneration of the liquid-phase membrane itself for each individual analysis cycle in a fully automated mode. Using hexavalent chromium as a model analyte and 1,5-diphenylcarbazide as a chromogenic probe in the acceptor solution, the flow-based HF-LPME hyphenated system was harnessed to the clean-up of troublesome samples (viz., domestic wastewater and soil leachates) with concomitant enrichment of target species. Distinct extraction modes and chemistries were assessed for enhanced Cr(VI) permeability. A single sample plug was subjected to a twofold backward-forward flow extraction so as to decrease the thickness of the boundary layer at the HF shell side for improved extraction efficiency. Under the optimized physicochemical variables, a limit of detection of 4.6 μg L(-1) Cr(VI), a dynamic linear range of up to 500 μg L(-1) and intermediate precision better than 10 % were obtained for a sample volume of 2.8 mL buffered at pH 4 and a volume of organic extractant of 120 μL, with an enrichment factor of ca. 11 for a sample residence time in the donor compartment of merely 4.5 min. Analyte recoveries in domestic wastewaters were ≥83 % using external calibration with relative standard deviations better than 14 %, thereby demonstrating the expedient clean-up of samples with elevated content of dissolved organic carbon. The automatic HF-LPME method was validated in terms of bias against the SRM 2701 (NIST soil) preceded by the EPA alkaline digestion method 3060A

  7. Application of hollow fiber liquid phase microextraction for simultaneous determination of regulated and emerging iodinated trihalomethanes in drinking water.

    Science.gov (United States)

    Domínguez-Tello, A; Arias-Borrego, A; García-Barrera, T; Gómez-Ariza, J L

    2015-07-10

    Trihalomethanes (THMs) are regulated disinfection by-products (DBPs) most commonly analyzed in quality control water supply due to their harmful effects on health. However, few data exist about the content of emerging iodo-trihalomethanes (I-THMs) which are present in drinking water at very low concentrations (in the order of ngL(-1)). For this reason a two-phase hollow fiber liquid phase microextraction method for the simultaneous determination of four regulated trihalomethanes and six emerging iodo-trihalomethanes using GC-μECD and GC-MS with detection limits in the range of few ngL(-1) has been developed. A central composite design was used to optimize conditions for simultaneous extraction. The best extraction recovery was obtained with 19.2min at 27.1°C and 900rpm, without salt addition, using a supported hollow fiber membrane of 10.5cm (0.6mm id) and 1-octanol as acceptor phase. The limits of detection for the regulated THMs and I-THMs were 3-44ngL(-1) and 1-3ngL(-1), respectively. The calibration curves showed good linearity (R(2)>0.995) and good repeatibility (3-22%). The relative recoveries in water were between 96.5% and 105.2%. The method was applied for the simultaneous determination of trihalomethanes in supply water samples from seven water distribution systems (WDS) in the Huelva area, located at the southwest Spain, which use different water-treatment processes. The highest concentrations of I-THMs, particularly CHBrClI and CHCl2I, were detected in water treated with advanced treatment process using pre-ozonation, however these compounds were not detected or decreased along distribution system. In the samples of treated water with conventional treatment, using pre-oxidation by permanganate and distribution network, CHCl2I, CHBrClI, CHClI2, CHBrI2 and CHI3 were detected at very low concentrations (1-18ngL(-1)). Finally, in water samples from underground origin without oxidation treatment, in which only disinfection with sodium hypochlorite was

  8. Simultaneous quantification of amphetamines, caffeine and ketamine in urine by hollow fiber liquid phase microextraction combined with gas chromatography-flame ionization detector.

    Science.gov (United States)

    Xiong, Jun; Chen, Jie; He, Man; Hu, Bin

    2010-08-15

    A method of hollow fiber (HF) liquid phase microextraction (LPME) combined with gas chromatography (GC)-flame ionization detection (FID) was developed for the simultaneous quantification of trace amphetamine (AP), methamphetamine (MA), methylenedioxyamphetamine (MDA), methylenedioxymethamphetamine (MDMA), caffeine and ketamine (KT) in drug abuser urine samples. The factors affecting on the extraction of six target analytes by HF-LPME were investigated and optimized, and the subsequent analytical performance evaluation and real sample analysis were performed by the extraction of six target analytes in sample solution containing 30% NaCl (pH 12.5) for 20 min with extraction temperature of 30 degrees C and stirring rate of 1000 rpm. Under such optimal conditions, the limits of detection (LODs, S/N=3) for the six target analytes were ranged from 8 microg/L (AP, KT) to 82 microg/L (MDA), with the enrichment factors (EFs) of 5-227 folds, and the relative standard deviations (RSDs, n=7) were in the range of 6.9-14.1%. The correlation coefficients of the calibration for the six target analytes over the dynamic linear range were higher than 0.9958. The application feasibility of HF-LPME-GC-FID in illegal drug monitoring was demonstrated by analyzing drug abuser urine samples, and the recoveries of target drugs for the spiked sample ranging from 75.2% to 119.3% indicated an excellent anti-interference capability of the developed method. The proposed method is simple, effective, sensitive and low-cost, and provides a much more accurate and sensitive detection platform over the conventional analytical techniques (such as immunological assay) for drug abuse analysis.

  9. Three-phase hollow-fiber liquid-phase microextraction combined with HPLC-UV for the determination of isothiazolinone biocides in adhesives used for food packaging materials.

    Science.gov (United States)

    Rosero-Moreano, Milton; Canellas, Elena; Nerín, Cristina

    2014-02-01

    The present study deals with the development of a liquid microextraction procedure for enhancing the sensitivity of the determination of 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one in adhesives. The procedure involves a three-phase hollow-fiber liquid-phase microextraction using a semipermeable polypropylene membrane, which contained 1-octanol as the organic phase in the pores of the membrane. The donor and acceptor phases are aqueous acidic and alkaline media, respectively, and the final liquid phase (acceptor) is analyzed by HPLC coupled with diode array detection. The most appropriate conditions were extraction time 20 min, stirring speed 1400 rpm, extraction temperature 50°C. The quantification limits of the method were 0.123 and 0.490 μg/g for 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one, respectively. Three different adhesive samples were successfully analyzed. The procedure was compared to direct analysis using ultra high pressure liquid chromatography coupled with TOF-MS, where the identification of the compounds and the quantification values were confirmed.

  10. Agarose film liquid phase microextraction combined with gas chromatography-mass spectrometry for the determination of polycyclic aromatic hydrocarbons in water.

    Science.gov (United States)

    Sanagi, Mohd Marsin; Loh, Saw Hong; Wan Ibrahim, Wan Aini; Hasan, Mohamed Noor

    2012-11-01

    Agarose film liquid phase microextraction (AF-LPME) procedure for the extraction and preconcentration of polycyclic aromatic hydrocarbons (PAHs) in water has been investigated. Agarose film was used for the first time as an interface between donor and acceptor phases in liquid phase microextraction which allowed for selective extraction of the analytes prior to gas chromatography-mass spectrometry. Using 1-octanol as acceptor phase, high enrichment factors in the range of 57-106 for the targeted analytes (fluorene, phenanthrene, fluoranthene and pyrene) were achieved. Under the optimum extraction conditions, the method showed good linearity in the range of 0.1-200 μgL(-1), good correlation coefficients in the range of 0.9963-0.9999, acceptable reproducibility (RSD 6.1-9.2%, n=3), low limits of detection (0.01-0.04 μgL(-1)) and satisfactory relative recoveries (92.9-104.7%). As the AF-LPME device was non-expensive, reuse or recycle of the film was not required, thus eliminating the possibility of analytes carry-over between runs. The AF-LPME technique is environment-friendly and compatible with the green chemistry concept as agarose is biodegradable polysaccharide extracted from seaweed and the procedure requires small volume of organic solvent and generates little waste. The validated method was successfully applied to the analysis of the four analytes in river water samples.

  11. Application of Liquid Phase Microextraction in the Determination of Pesticide Residues%液相微萃取在农药残留物检测中的应用

    Institute of Scientific and Technical Information of China (English)

    熊玉宝; 张勇; 廖春华; 邱清权

    2011-01-01

    Pesticide residues were at a very low level. They also coexisted with their homologs. isomers, degradation products and metabolites etc. Pretreatment technologies of pesticide residues were the key of their analysis and detection.As a new pretreatment technology,liquid phase microextraction technology played an important role in sample preparation. Herein we would introduce three liquid phase microextraction technologies: hollow fiber liquid phase microextraction technology, head space liquid phase microextraction technology and dispersed liquid phase microextraction technology. These three kinds of technologies were compared, and their applications in pesticide residues detection being recommended. And the prospects of liquid phase microextraction technology were predicted.%残留农药的含量极低,而且还与其同系物、异构体、降解产物、代谢产物等共存.农药残留前处理技术成为农药残留分析检测中的关键.作为一种新型的样品前处理技术,液相微萃取技术扮演着重要的角色.文章将介绍3种液相微萃取技术:中空纤维液相微萃取技术、顶空液相微萃取技术和分散液相微萃取技术,对这3种技术进行了比较,重点介绍了它们在农药残留物检测中的应用,并对液相微萃取技术的发展前景予以展望.

  12. Selective determination of inorganic cobalt in nutritional supplements by ultrasound-assisted temperature-controlled ionic liquid dispersive liquid phase microextraction and electrothermal atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Berton, Paula; Martinis, Estefania M. [Analytical Chemistry Research and Development Group (QUIANID), (LISAMEN-CCT-CONICET-Mendoza), Av. Ruiz Leal S/N Parque General San Martin, M 5502 IRA Mendoza (Argentina); Martinez, Luis D. [INQUISAL-CONICET, Departamento de Quimica Analitica, Facultad de Quimica, Bioquimica y Farmacia, Universidad Nacional de San Luis, San Luis (Argentina); Wuilloud, Rodolfo G., E-mail: rwuilloud@mendoza-conicet.gob.ar [Analytical Chemistry Research and Development Group (QUIANID), (LISAMEN-CCT-CONICET-Mendoza), Av. Ruiz Leal S/N Parque General San Martin, M 5502 IRA Mendoza (Argentina); Instituto de Ciencias Basicas, Universidad Nacional de Cuyo, Mendoza (Argentina)

    2012-02-03

    Highlights: Black-Right-Pointing-Pointer Synergy of ultrasound energy and TILDLME technique for improved metal extraction. Black-Right-Pointing-Pointer Highly selective determination of inorganic Co species at trace levels. Black-Right-Pointing-Pointer Speciation analysis of Co in several nutritional supplements with highly complex matrices. Black-Right-Pointing-Pointer Development of an environmentally friendly microextraction technique with minimal waste production and sample consumption. - Abstract: In the present work, a simple and rapid analytical method based on application of ionic liquids (ILs) for inorganic Co(II) species (iCo) microextraction in a variety of nutrient supplements was developed. Inorganic Co was initially chelated with 1-nitroso-2-naphtol (1N2N) reagent followed by a modern technique named ultrasound-assisted temperature-controlled ionic liquid dispersive liquid phase microextraction (USA-TILDLME). The extraction was performed with 1-hexyl-3-methylimidazolium hexafluorophosphate [C{sub 6}mim][PF{sub 6}] with the aid of ultrasound to improve iCo recovery. Finally, the iCo-enriched IL phase was solubilized in methanol and directly injected into an electrothermal atomic absorption spectrometer (ETAAS). Several parameters that could influence iCo microextraction and detection were carefully studied. Since the main difficulty in these samples is caused by high concentrations of potential interfering ions, different approaches were evaluated to eliminate interferences. The limit of detection (LOD) was 5.4 ng L{sup -1}, while the relative standard deviation (RSD) was 4.7% (at 0.5 {mu}g L{sup -1} Co level and n = 10), calculated from the peak height of absorbance signals. Selective microextraction of iCo species was achieved only by controlling the pH value during the procedure. The method was thus successfully applied for determination of iCo species in nutritional supplements.

  13. Enhancement of Sensitivity for Determination of Phenols in Environmental Water Samples by Single-drop Liquid Phase Microextraction Using Ionic Liquid prior to HPLC

    Institute of Scientific and Technical Information of China (English)

    Qing Xiang ZHOU; Jun Ping XIAO; Cun Ling YE; Xin Ming WANG

    2006-01-01

    A single-drop liquid phase micro-extraction procedure using 1-butyl-3-methylimidazolium hexafluorophosphate ([C4MIM][PF6]) was demonstrated for the sensitive determination of four phenols in water samples. Under the optimized conditions, the linear range of proposed phenol, 2-naphthol, 2-nitrophenol and 4-chlorophenol, respectively. The experimental results indicated that the effect of complex matrices natural water samples could be resolved with addition of sodium ethylene diamine tetracetate (EDTA) into the samples. Excellent spiked recoveries were achieved for these four phenols ranged from 86.2%-114.9 %. All these facts demonstrated that the proposed method with merits of low cost, simplicity and easy operating would be a competitive alternative procedure for the determination of such compounds at trace level.

  14. Advances in Liquid Phase Microextraction Based on Microfluidic Chip%基于微流控芯片的液相微萃取的研究进展

    Institute of Scientific and Technical Information of China (English)

    吴哲宽; 覃光炯

    2015-01-01

    The microfluidic chip integrates mixing, reaction, extraction and concentration together through the microchannel network in a chip, which provides an excellent platform for the miniaturization of extraction. With the special surface physical properties of the liquid in micro scale, liquid phase microextraction operated on the microfluidic chip has great potential to realize the fast extraction equilibrium and preconcentration of analytes with small sample volume. Based on microfluidic chip in the past decade, the development and application of liquid phase microextraction were focused on, several extraction modes were summarized, such as laminar flow, fluidic drop and drop-trapped.%微流控芯片通过微通道网络,将样品的采集、混合、反应、分离和富集等分析过程集成在芯片上完成,为化学反应的微型化提供了一个良好的操作平台。利用液体在微观尺度下表现出的特殊的表面物理性质,将液相微萃取技术移植到微流控芯片上,可以实现小体积样品中低含量目标分析物的萃取。本文介绍了基于微流控芯片的液相微萃取近年的研究进展,并总结了层流、液滴、捕陷液滴几种基本的萃取模式。

  15. Stirring-controlled solidified floating solid-liquid drop microextraction as a new solid phase-enhanced liquid-phase microextraction method by exploiting magnetic carbon nanotube-nickel hybrid.

    Science.gov (United States)

    Ghazaghi, Mehri; Mousavi, Hassan Zavvar; Shirkhanloo, Hamid; Rashidi, Alimorad

    2017-01-25

    A specific technique is introduced to overcome limitations of classical solidification of floating organic drop microextraction, such as tedious and time-consuming centrifuge step and using disperser solvent, by facile and efficient participation of solid and liquid phases. In this proposed method of stirring-controlled solidified floating solid-liquid drop microextraction (SC-SF-SLDME), magnetic carbon nanotube-nickel hybrid (MNi-CNT) as a solid part of the extractors are dispersed ultrasonically in sample solution, and the procedure followed by dispersion of liquid phase (1-undecanol) through high-rate stirring and easily recollection of MNi-CNT in organic solvent droplets through hydrophobic force. With the reduction in speed of stirring, one solid-liquid drop is formed on top of the solution. MNi-CNT acts as both extractor and the coalescence helper between organic droplets for a facile recollection. MNi-CNT was prepared by spray pyrolysis of nickel oleate/toluene mixture at 1000 °C. Four tyrosine kinase inhibitors were selected as model analytes and the effecting parameters were investigated. The results confirmed that magnetic nanoadsorbent has an important role in the procedure and complete collection of dispersed solvent is not achieved in the absence of the solid phase. Also, short extraction time exhibited success of the proposed method and effect of dispersed solid/liquid phases. The limits of quantification (LOQs) for imatinib, sunitinib, erlotinib, and nilotinib were determined to be as low as 0.7, 1.7, 0.6, and 1.0 μg L(-1), respectively. The intra-day precisions (RSDs) were lower than 4.5%. Method performance was investigated by determination of mentioned tyrosine kinase inhibitors (TKIs) in human serum and cerebrospinal fluid samples with good recoveries in the range of 93-98%.

  16. Vortex-assisted hollow fibre liquid-phase microextraction technique combined with high performance liquid chromatography-diode array detection for the determination of oestrogens in milk samples.

    Science.gov (United States)

    Wang, Peijin; Xiao, Yu; Liu, Wenjun; Wang, Juan; Yang, Yaling

    2015-04-01

    A rapid, simple, sensitive and environmentally friendly method has been developed for the determination of three oestrogens (17β-estradiol (17β-E2), estrone (E1), and diethylstilbestrol (DES)) in milk samples by using vortex-assisted hollow fibre liquid-phase microextraction (VA-HF-LPME) and high performance liquid chromatography. Method is based on the microextraction of oestrogens from sample solution into 15 μL of nonanoic acid as extracting agent, which is placed inside the hollow fibre followed by vortex-mixing. Vortex provided effective and mild mixing of sample solution and increased the contact between analytes and boundary layers of the hollow fibre, thereby enhancing mass transfer rate and leading to high recovery of target analytes. The extraction equilibrium is achieved within 2 min. Parameters influencing the recovery were investigated and optimized. The proposed technique provided good linearity (>0.9984), repeatability (RSD = 2.56-4.38), low limits of detection (0.06-0.17 ng mL(-1)), and high enrichment factor (330).

  17. Simultaneous extraction and quantification of albendazole and triclabendazole using vortex-assisted hollow-fiber liquid-phase microextraction combined with high-performance liquid chromatography.

    Science.gov (United States)

    Asadi, Mohammad; Haji Shabani, Ali Mohammad; Dadfarnia, Shayessteh

    2016-06-01

    A novel, simple, and rapid vortex-assisted hollow-fiber liquid-phase microextraction method was developed for the simultaneous extraction of albendazole and triclabendazole from various matrices before their determination by high-performance liquid chromatography with fluorescence detection. Several factors influencing the microextraction efficiency including sample pH, nature and volume of extraction solvent, ionic strength, vortex time, and sample volume were investigated and optimized. Under the optimal conditions, the limits of detection were 0.08 and 0.12 μg/L for albendazole and triclabendazole, respectively. The calibration curves were linear in the concentration ranges of 0.3-50.0 and 0.4-50.0 μg/L with the coefficients of determination of 0.9999 and 0.9995 for albendazole and triclabendazole, respectively. The interday and intraday relative standard deviations for albendazole and triclabendazole at three concentration levels (1.0, 10.0, and 30.0 μg/L) were in the range of 6.0-11.0 and 5.0-7.9%, respectively. The developed method was successfully applied to determine albendazole and triclabendazole in water, milk, honey, and urine samples.

  18. Application of hollow fibre liquid phase microextraction for the multiresidue determination of pesticides in alcoholic beverages by ultra-high pressure liquid chromatography coupled to tandem mass spectrometry.

    Science.gov (United States)

    Bolaños, P Plaza; Romero-González, R; Frenich, A Garrido; Vidal, J L Martínez

    2008-10-24

    An alternative method has been developed to determine more than 50 pesticides in alcoholic beverages using hollow fibre liquid phase microextraction (HF-LPME) followed by ultra-high pressure liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS), without any further clean-up step. Pesticides were extracted from the sample to the organic solvent immobilized in the fibre and they were desorbed in methanol prior to chromatographic analysis. Experimental parameters related to microextraction such as type of organic solvent, extraction time and agitation rate have been optimized. The extraction method has been validated for several types of alcoholic beverages such as wine and beer, and no matrix effect was observed. The technique requires minimal sample handling and solvent consumption. Using optimum conditions, low detection limits (0.01-5.61microgL(-1)) and good linearity (R(2)>0.95) were obtained. Repeatability and interday precision ranged from 3.0 to 16.8% and from 5.9 to 21.2%, respectively. Finally the optimized method was applied to real samples and carbaryl, triadimenol, spyroxamine, epoxiconazole, triflumizol and fenazaquin were detected in some of the analyzed samples. The obtained results indicated that the new method can be successfully applied for extraction and determination of pesticides in alcoholic beverages, increasing sample throughput.

  19. Simultaneous speciation and preconcentration of ultra traces of inorganic tellurium and selenium in environmental samples by hollow fiber liquid phase microextraction prior to electrothermal atomic absorption spectroscopy determination.

    Science.gov (United States)

    Ghasemi, Ensieh; Najafi, Nahid Mashkouri; Raofie, Farhad; Ghassempour, Alireza

    2010-09-15

    A simple and effective speciation and preconcentration method based on hollow fiber liquid phase microextraction (HF-LPME) was developed for simultaneous separation of trace inorganic tellurium and selenium in environmental samples prior to electrothermal atomic absorption spectroscopy (ETAAS) determination. The method involves the selective extraction of the Te (IV) and Se (IV) species by HF-LPME with the use of ammonium pyrrolidinecarbodithioate (APDC) as the chelating agent. The complex compounds were extracted into 10 microL of toluene and the solutions were injected into a graphite furnace for the determination of Te (IV) and Se (IV). To determine the total tellurium and selenium in the samples, first Te (VI) and Se (VI) were reduced to Te (IV) and Se (IV), and then the microextraction method was performed. The experimental parameters of HF-LPME were optimized using a central composite design after a 2(n-1) fractional factorial experimental design. Under optimum conditions, enrichment factors of up to 520 and 480 were achieved for Te (IV) and Se (IV), respectively. The detection limits were 4 ng L(-1) with 3.5% RSD (n=5, c=2.0 microg L(-1)) for Te (IV) and 5 ng L(-1) with 3.1% RSD for Se (IV). The applicability of the developed technique was evaluated by application to spiked, environmental water and soil samples.

  20. 液相微萃取技术在农药残留分析中的应用研究进展%Review on the application of liquid phase microextraction in pesticide residue analysis

    Institute of Scientific and Technical Information of China (English)

    王素利; 杨素萍; 刘丰茂; 薛佳莹; 尤祥伟

    2012-01-01

    Liquid phase microextraction (LPME) is one of novel sample pretreatment techniques which has many advantages such as quick, simple, economic, highly selective and accurate, less-solvent consuming and environmental friendly. It can be matched easily with most of analytical instruments. It includes several types such as single drop microextraction ( SDME) , hollow fiber liquid phase microextraction ( HF-LPME) , dispersive liquid-liquid microextraction ( DLLME ) , solidified floating organic drop microextraction ( SFODME) , continuous-flow microextraction ( CFME ) and directly-suspended droplet microextraction (DSDME) etc. It is a very potential sample pretreatment technique for theoretic and application studies. In this review, the historical development and overview of these miniaturized liquid phase extraction methodologies were discussed and a comprehensive collection of application of these methods for preconcentration and determination of pesticide residue in various matrices were summarized.%液相微萃取技术(LPME)是一种新型的样品前处理方法,具有快速、简单、廉价、选择性强、准确度高、溶剂消耗量少、环境污染小等优点,方便与各种分析仪器联用.其具有多种模式:单滴液相微萃取(SDME)、中空纤维液相微萃取(HF-LPME)、分散液相微萃取(DLLME)、悬浮固化液微萃取(SFODME)、连续流动微萃取(CFME)、直接悬挂液滴微萃取(DSDME)等,具有很好的研究潜力和应用前景.对液相微萃取技术在农药残留分析中的应用研究进展进行了综述.

  1. Switchable polarity solvent for liquid phase microextraction of Cd(II) as pyrrolidinedithiocarbamate chelates from environmental samples

    Energy Technology Data Exchange (ETDEWEB)

    Yilmaz, Erkan, E-mail: kimyager_erkan@hotmail.com; Soylak, Mustafa, E-mail: soylak@erciyes.edu.tr

    2015-07-30

    A switchable polarity solvent was synthesized from triethylamine (TEA)/water/CO{sub 2} (Dry ice) via proton transfer reaction has been used for the microextraction of cadmium(II) as pyrrolidinedithiocarbamate (APDC) chelate. Cd(II)-APDC chelate was extracted into the switchable polarity solvent drops by adding 2 mL 10 M sodium hydroxide solution. Analytical parameters affecting the complex formation and microextraction efficiency such as pH, amount of ligand, volume of switchable polarity solvent and NaOH, sample volume were optimized. The effects of foreign ions were found tolerably. Under optimum conditions, the detection limit was 0.16 μg L{sup −1} (3Sb/m, n = 7) and the relative standard deviation was 5.4% (n = 7). The method was validated by the analysis of certified reference materials (TMDA-51.3 fortified water, TMDA-53.3 fortified water and SPS-WW2 waste water, 1573a Tomato Leaves and Oriental Basma Tobacco Leaves (INCT-OBTL-5)) and addition/recovery tests. The method was successfully applied to determination of cadmium contents of water, vegetable, fruit and cigarette samples. - Highlights: • Switchable polarity solvent was synthesized from triethylamine (TEA)/water/CO{sub 2}. • The switchable polarity solvent has been used for the microextraction of cadmium(II). • The important factors were optimized. • The method was applied to determination of cadmium in real samples.

  2. 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.

  3. Hollow fiber liquid phase microextraction combined with electrothermal atomic absorption spectrometry for the speciation of arsenic (III) and arsenic (V) in fresh waters and human hair extracts

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Hongmei [Department of Chemistry, Wuhan University, Wuhan 430072 (China); Hu Bin [Department of Chemistry, Wuhan University, Wuhan 430072 (China)], E-mail: binhu@whu.edu.cn; Chen Beibei; Xia Linbo [Department of Chemistry, Wuhan University, Wuhan 430072 (China)

    2009-02-16

    A new method of hollow fiber liquid phase microextraction (HF-LPME) using ammonium pyrrolidine dithiocarbamate (APDC) as extractant combined with electrothermal atomic absorption spectrometry (ETAAS) using Pd as permanent modifier has been described for the speciation of As(III) and As(V). In a pH range of 3.0-4.0, the complex of As(III)-APDC complex can be extracted using toluene as the extraction solvent leaving As(V) in the aqueous layer. The post extraction organic phase was directly injected into ETAAS for the determination of As(III). To determine total arsenic in the samples, first As(V) was reduced to As(III) by L-cysteine, and then a microextraction method was performed prior to the determination of total arsenic. As(V) assay was based on subtracting As(III) form the total arsenic. All parameters, such as pH of solution, type of organic solvent, the amount of APDC, stirring rate and extraction time, affecting the separation of As(III) from As(V) and the extraction efficiency of As(III) were investigated, and the optimized extraction conditions were established. Under optimized conditions, a detection limit of 0.12 ng mL{sup -1} with enrichment factor of 78 was achieved. The relative standard deviation (R.S.D.) of the method for five replicate determinations of 5 ng mL{sup -1} As(III) was 8%. The developed method was applied to the speciation of As(III) and As(V) in fresh water and human hair extracts, and the recoveries for the spiked samples are 86-109%. In order to validate the developed method, three certified reference materials such as GBW07601 human hair, BW3209 and BW3210 environmental water were analyzed, and the results obtained were in good agreement with the certified values provided.

  4. 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.

  5. Dynamic study in partial transient liquid phase bonding of Si3N4

    Institute of Scientific and Technical Information of China (English)

    邹家生; 初雅杰; 许志荣; 陈光

    2004-01-01

    Dynamics in partial transient liquid phase bonding (PTLP bonding) of Si3N4 ceramic with Ti/Cu/Ti multi-interlayer was systematically studied through micro-analysis of joint interfaces. The results show that growth of reaction layer and isothermal solidification procession do at the same time. Growth of reaction layer and moving of isothermal solidification interface obey the parabolic law governed by the diffusion of participating elements during the PTLP bonding. Coordination of the above two dynamics process is done through time and temperature. When reaction layer thickness is suitable and isothermal solidification process is finished, the high bonding strength at room temperature and high temperature are obtained.

  6. 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.

  7. Comparison of hollow fiber liquid-phase microextraction and ultrasound-assisted low-density solvent dispersive liquid-liquid microextraction for the determination of drugs of abuse in biological samples by gas chromatography-mass spectrometry.

    Science.gov (United States)

    Meng, Liang; Zhang, Wenwen; Meng, Pinjia; Zhu, Binling; Zheng, Kefang

    2015-05-01

    Two microextraction techniques based on hollow fiber liquid-phase microextraction (HF-LPME) and ultrasound-assisted low-density solvent dispersive liquid-liquid microextraction (UA-LDS-DLLME) had been applied for the determination of drugs of abuse (methamphetamine, amphetamine, 3,4-methylenedioxymethamphetamine, 3,4-methylenedioxyamphetamine, methcathinone, ketamine, meperidine, and methadone) in urine and blood samples by gas chromatography-mass spectrometry. Parameters affecting extraction efficiency have been investigated and optimized for both methods. Under the optimum conditions, linearities were observed for all analytes in the range 0.0030-10 μg/ml with the correlation coefficient (R) ranging from 0.9985 to 0.9995 for HF-LPME and in the range 0.0030-10 μg/ml with the R ranging from 0.9985 to 0.9994 for DLLME. The recovery of 79.3-98.6% with RSDs of 1.2-4.5% was obtained for HF-LPME, and the recovery of 79.3-103.4% with RSDs of 2.4-5.7% was obtained for DLLME. The LODs (S/N=3) were estimated to be in the range from 0.5 to 5 ng/ml and 0.5 to 4 ng/ml, respectively. Compared with HF-LPME, the UA-LDS-DLLME technique had the advantages of less extraction time, suitability for batches of sample pretreatment simultaneously, and higher extraction efficiency, while HF-LPME has excellent sample clean-up effect, and is a robust and suitable technique for various sample matrices with better repeatability. Both methods were successfully applied to the analysis of drugs of abuse in real human blood sample.

  8. 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.

  9. Hyperbranched polyglycerol/graphene oxide nanocomposite reinforced hollow fiber solid/liquid phase microextraction for measurement of ibuprofen and naproxen in hair and waste water samples.

    Science.gov (United States)

    Rezaeifar, Zohreh; Es'haghi, Zarrin; Rounaghi, Gholam Hossein; Chamsaz, Mahmoud

    2016-09-01

    A new design of hyperbranched polyglycerol/graphene oxide nanocomposite reinforced hollow fiber solid/liquid phase microextraction (HBP/GO -HF-SLPME) coupled with high performance liquid chromatography used for extraction and determination of ibuprofen and naproxen in hair and waste water samples. The graphene oxide first synthesized from graphite powders by using modified Hummers approach. The surface of graphene oxide was modified using hyperbranched polyglycerol, through direct polycondensation with thionyl chloride. The ready nanocomposite later wetted by a few microliter of an organic solvent (1-octanol), and then applied to extract the target analytes in direct immersion sampling mode.After the extraction process, the analytes were desorbed with methanol, and then detected via high performance liquid chromatography (HPLC). The experimental setup is very simple and highly affordable. The main factors influencing extraction such as; feed pH, extraction time, aqueous feed volume, agitation speed, the amount of functionalized graphene oxide and the desorption conditions have been examined in detail. Under the optimized experimental conditions, linearity was observed in the range of 5-30,000ngmL(-1) for ibuprofen and 2-10,000ngmL(-1) for naproxen with correlation coefficients of 0.9968 and 0.9925, respectively. The limits of detection were 2.95ngmL(-1) for ibuprofen and 1.51ngmL(-1) for naproxen. The relative standard deviations (RSDs) were found to be less than 5% (n=5).

  10. Application of magnetic solvent bar liquid-phase microextraction for determination of organophosphorus pesticides in fruit juice samples by gas chromatography mass spectrometry.

    Science.gov (United States)

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

    2015-06-01

    A simple, rapid and sensitive sample pretreatment technique, magnetic solvent bar liquid-phase microextraction (MSB-LPME) was developed for extracting organophosphorus pesticides from fruit juice. The analytes were extracted from the sample to the organic solvent immobilized in the fiber. The magnetic solvent bar not only can be used to stir the samples but also extract the analytes. After extraction, the analyte-adsorbed magnetic solvent bar can be readily isolated from the sample solution by a magnet, which could greatly simplify the operation and reduce the whole pretreatment time. The bar was eluted with methanol. The elute was evaporated to dryness and residue was dissolved in hexane. Several experimental parameters were investigated and optimized, including type of extraction solvent, number of magnetic solvent bar, extraction temperature, extraction time, salt concentration, stirring speed, pH and desorption conditions. The recoveries were in the range of 81.3-104.6%, and good reproducibilities were obtained with relative standard deviation below 6.1%.

  11. Optimization of dispersive liquid-phase microextraction based on solidified floating organic drop combined with high-performance liquid chromatography for the analysis of glucocorticoid residues in food.

    Science.gov (United States)

    Huang, Yuan; Zheng, Zhiqun; Huang, Liying; Yao, Hong; Wu, Xiao Shan; Li, Shaoguang; Lin, Dandan

    2017-05-10

    A rapid, simple, cost-effective dispersive liquid-phase microextraction based on solidified floating organic drop (SFOD-LPME) was developed in this study. Along with high-performance liquid chromatography, we used the developed approach to determine and enrich trace amounts of four glucocorticoids, namely, prednisone, betamethasone, dexamethasone, and cortisone acetate, in animal-derived food. We also investigated and optimized several important parameters that influenced the extraction efficiency of SFOD-LPME. These parameters include the extractant species, volumes of extraction and dispersant solvents, sodium chloride addition, sample pH, extraction time and temperature, and stirring rate. Under optimum experimental conditions, the calibration graph exhibited linearity over the range of 1.2-200.0ng/ml for the four analytes, with a reasonable linearity(r(2): 0.9990-0.9999). The enrichment factor was 142-276, and the detection limits was 0.39-0.46ng/ml (0.078-0.23μg/kg). This method was successfully applied to analyze actual food samples, and good spiked recoveries of over 81.5%-114.3% were obtained.

  12. Development of Hollow-Fiber Liquid-Phase Microextraction Method for Determination of Urinary trans,trans-Muconic Acid as a Biomarker of Benzene Exposure

    Science.gov (United States)

    Ghamari, Farhad; Bahrami, Abdulrahman; Yamini, Yadollah; Shahna, Farshid Ghorbani; Moghimbeigi, Abbas

    2016-01-01

    For the first time, hollow-fiber liquid-phase microextraction combined with high-performance liquid chromatography–ultraviolet was used to extract trans,trans-muconic acid, in urine samples of workers who had been exposed to benzene. The parameters affecting the metabolite extraction were optimized as follows: the volume of sample solution was 11 mL with pH 2, liquid membrane containing dihexyl ether as the supporter, 15% (w/v) of trioctylphosphine oxide as the carrier, the time of extraction was 120 minutes, and stirring rate was 500 rpm. Organic phase impregnated in the pores of a hollow fiber was extracted into 24 µL solution of 0.05 mol L−1 Na2CO3 located inside the lumen of the fiber. Under optimized conditions, a high enrichment factor of 153–182 folds, relative recovery of 83%–92%, and detection limit of 0.001 µg mL−1 were obtained. The method was successfully applied to the analysis of ttMA in real urine samples. PMID:27660405

  13. Hollow fiber based liquid phase microextraction for the determination of organochlorine pesticides in ecological textiles by gas chromatography-mass spectrometry.

    Science.gov (United States)

    Cai, Jin'an; Chen, Guosheng; Qiu, Junlang; Jiang, Ruifen; Zeng, Feng; Zhu, Fang; Ouyang, Gangfeng

    2016-01-01

    In this study, the hollow fiber-liquid phase microextraction (HF-LPME) coupled gas chromatograph/mass spectrometry (GC/MS) was firstly developed to determine 10 organochlorine pesticides (OCPs) in ecological textiles. The present method can offer high separation efficiencies with minimal sample and solvent consumption. The extraction conditions were optimized, including the types of hollow fiber and organic solvent, the extraction time, the stirring and the salinity. Under the optimized conditions, the linear ranges of OCPs in cotton, terylene and fur samples were 5-1000 ng/g, 10-1000 ng/g and 10-800 ng/g, respectively, and the detection limit of the three samples were 0.07-2.30 ng/g, 0.89-1.66 ng/g and 0.06-1.04 ng/g, respectively. The optimized method was then successfully used to determine the OCPs in 3 kinds of spiked real samples, including cotton, terylene and fur. The good recoveries and RSDs of the quantification in real textile samples were obtained and the results were confirmed by the traditional liquid extraction method (GB/T 18412-2006). This study proved that the HF-LPME method, which was simple, low-cost and virtually solvent-free, was reliable for the qualitative and quantitative analysis of the harmful OCP residues in ecological textiles.

  14. Determination of nitrophenolic compounds from atmospheric particles using hollow-fiber liquid-phase microextraction and capillary electrophoresis/mass spectrometry analysis.

    Science.gov (United States)

    Teich, Monique; van Pinxteren, Dominik; Herrmann, Hartmut

    2014-05-01

    A hollow-fiber liquid-phase microextraction method was developed to enrich nine nitrophenolic compounds from aqueous extracts of atmospheric aerosol particles. Analysis was performed by CE coupled with ESI MS. The BGE composition was optimized to a 20 mM ammonium acetate buffer at pH 9.7 containing 15% methanol v/v. Several extraction parameters (composition of organic liquid membrane, pH of acceptor phase, salting-out effect, extraction time) were investigated for their effect on the analyte recoveries. The donor phase consisted of a 1.8 mL sample solution kept at pH 2 while the acceptor phase was a 15 μL 100 mM aqueous ammonia solution. Dihexyl ether served as supported liquid membrane. Low detection limits in the range of nanomole per liter were achieved. Recoveries of aqueous standard solutions were found to be between 11 and 90% with enrichment factors between 10 and 100. Interday and intraday repeatabilities were in an acceptable range for most compounds (6-15% and 7-10%, respectively) but somewhat higher for 4-nitrocatechol (59 and 48%) and 2-nitrophenol (17 and 35%). The developed method was found to be competitive with more established method and was successfully applied to samples of atmospheric particulate matter from field experiments.

  15. Simple and Rapid Hollow Fiber Liquid Phase Microextraction Followed by High Performance Liquid Chromatography Method for Determination of Drug-protein Binding

    Institute of Scientific and Technical Information of China (English)

    XI Guo-chen; HU Shuang; BAI Xiao-hong

    2011-01-01

    A method was established using hollow fiber-liquid phase microextraction(HF-LPME) followed by high performance liquid chromatography(HPLC) to determine the concentration of the free(unbound) drug in the solution of the drug and protein.Measurements of drug-protein binding ratios and free drug concentrations were then analyzed with the Klotz equation to determine the equilibrium binding constant and number of binding sites for drug-protein interaction.The optimized method allows one to perform the efficient extraction and separation of free drug from protein-bound drug,protein,and other interfering substances.This approach was used to characterize the binding of the anticholinergic drugs atropine sulfate and scopolamine hydrobromide to proteins in human plasma and bovine serum albumin(BSA).The results demonstrate the utility of HF-LPME method for measuring free drug concentrations in protein-drug mixtures and determining the protein binding parameters of a pharmacologically important class of drugs.

  16. Research on liquid-phase micro-extraction technology in pharmaceutical analysis%药物分析中的液相微萃取技术研究

    Institute of Scientific and Technical Information of China (English)

    郑艳燕

    2016-01-01

    液相微萃取技术(LPME)是将采样、富集和纯化融为一体,它有效降低了传统液-液萃取时有机溶液的应用量。有模式多样灵活、富集效率高、环境友好、操作简单的优点。为了在药物分析中充分发挥该技术的作用,通过对相关内容进行分析与论述,为有关单位及工作人员在实际工作中提供帮助。%Liquid-phase micro-extraction (LPME) integrates sampling, enrichment and purification, which effectively reduces the application amount of organic solution extracted from traditional liquid. It has advantages of flexible model, high enrichment efficiency, friendly environment and simple operation. To fully play its role this technology in pharmaceutical analysis, this paper made analysis and discussion on relevant content, hoping to provide help for relevant units and staff in practical work.

  17. Estimation of the toxicity of sulfadiazine to Daphnia magna using negligible depletion hollow-fiber liquid-phase microextraction independent of ambient pH

    Science.gov (United States)

    Liu, Kailin; Xu, Shiji; Zhang, Minghuan; Kou, Yahong; Zhou, Xiaomao; Luo, Kun; Hu, Lifeng; Liu, Xiangying; Liu, Min; Bai, Lianyang

    2016-12-01

    The toxicity of ionizable organic compounds to organisms depends on the pH, which therefore affects risk assessments of these compounds. However, there is not a direct chemical method to predict the toxicity of ionizable organic compounds. To determine whether hollow-fiber liquid-phase microextraction (HF-LPME) is applicable for this purpose, a three-phase HF-LPME was used to measure sulfadiazine and estimate its toxicity to Daphnia magna in solutions of different pH. The result indicated that the sulfadiazine concentrations measured by HF-LPME decreased with increasing pH, which is consistent with the decreased toxicity. The concentration immobilize 50% of the daphnids (EC50) in 48 h calculated from nominal concentrations increased from 11.93 to 273.5 mg L-1 as the pH increased from 6.0 to 8.5, and the coefficient of variation (CV) of the EC50 values reached 104.6%. When calculated from the concentrations measured by HF-LPME (pH 12 acceptor phase), the EC50 ranged from 223.4 to 394.6 mg L-1, and the CV decreased to 27.60%, suggesting that the concentrations measured by HF-LPME can be used to estimate the toxicity of sulfadiazine irrespective of the solution pH.

  18. On-line flow-injection liquid-phase microextraction and spectrophotometric determination of traces of copper(II) with trithia-9-crown-3 as complexing agent.

    Science.gov (United States)

    Zahedi, Mir Mahdi; Shamsipur, Mojtaba; Pourmortazavi, Seied Mahdi

    2013-01-01

    A novel on-line flow-injection liquid-phase microextraction (FI-LPME) and spectrophotometric determination of the Cu(2+) ion using trithia-9-crown-3 (TT9C3) as a sensitive and selective charge transfer complexing agent was developed. After phase segmentation by pulsating motions of a peristaltic pump, the phase separation takes place by the aid of gravitation forces. The optimum values of the pH (= 5 of phosphate buffer) and ionic strength (5 mM Na2SO4) of the solution, amount of ligand (2.0 × 10(-3) mol L(-1)), nature of the counter ion (10 mM SDS), volume of the organic solvent (150 μL), coil length (3 m) and extraction time (2 min) for an efficient extraction were determined. The calibration curve was found to be linear over a concentration range of 0.008 - 4.2 μg mL(-1) (R(2) = 0.9985) with a limit of detection of 0.37 ng mL(-1). The enrichment factor and relative standard deviation (n = 7) were 16 and 5.7%, respectively. Finally, the proposed method was applied to the determination of copper(II) as an impurity in the several commercial metallic salts.

  19. Pseudo-stir bar hollow fiber solid/liquid phase microextraction combined with anodic stripping voltammetry for determination of lead and cadmium in water samples.

    Science.gov (United States)

    Es'haghi, Zarrin; Hoseini, Hasan Ali; Mohammadi-Nokhandani, Saeed; Ebrahimi, Javad

    2014-11-01

    A new procedure is presented for the determination of low concentrations of lead and cadmium in water samples. Ligand assisted pseudo-stir bar hollow fiber solid/liquid phase microextraction using sol-gel sorbent reinforced with carbon nanotubes was combined with differential pulse anodic stripping voltammetry for simultaneous determination of cadmium and lead in tap water, and Darongar river water samples. In the present work, differential pulse anodic stripping voltammetry (DPASV) using a hanging mercury drop electrode (HMDE) was used in order to determine the ultra trace level of lead and cadmium ions in real samples. This method is based on accumulation of lead and cadmium ions on the electrode using different ligands; Quinolin-8-ol, 5,7-diiodo quinoline-8-ol, 4,5-diphenyl-1H-imidazole-2(3H)-one and 2-{[2-(2-Hydroxy-ethylamino)-ethylamino]-methyl}-phenol as the complexing agent. The optimized conditions were obtained. The relationship between the peak current versus concentration was linear over the range of 0.05-500 ng mL(-1) for Cd (II) and Pb (II). The limits of detection for lead and cadmium were 0.015 ng mL(-1) and 0.012 ng mL(-1), respectively. Under the optimized conditions, the pre-concentration factors are 2440 and 3710 for Cd (II) and Pb (II) in 5 mL of water sample, respectively.

  20. Automated hollow-fiber liquid-phase microextraction coupled with liquid chromatography/tandem mass spectrometry for the analysis of aflatoxin M₁ in milk.

    Science.gov (United States)

    Huang, Siming; Hu, Du; Wang, Ying; Zhu, Fang; Jiang, Ruifen; Ouyang, Gangfeng

    2015-10-16

    An automated hollow fiber liquid-phase microextraction (HF-LPME) coupled with liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was developed for the extraction and determination of aflatoxin M1 (AFM1) in milk samples. Parameters affecting the extraction efficiency, such as the extraction phase, matrix conditions, extraction time and temperature, were investigated. Under the optimal conditions (ratio of water to milk, 4:1; extraction time, 50 min; extraction temperature, 50°C; extraction phase, 50 mg L(-1) anti-AFM1 antibody in PBS buffer solution; volume of HCl solution, 250 μL; agitation speed, 250 rpm), the matrix-matched calibration curve for AFM1 determination showed good linearity in the range of 0.25-5 μg kg(-1). The enrichment factor (EF) reached 48, and the limits of detection and quantification were 0.06 and 0.21 μg kg(-1), respectively. The developed method was successfully applied for the extraction of AFM1 from spiked milk samples, with recoveries from 61.0% to 106.7%. The method was highly specific to AFM1 analysis, and the results demonstrated that the method can be automated, inexpensive, and free from interference.

  1. Comparison of hollow fiber liquid phase microextraction and dispersive liquid-liquid microextraction for the determination of organosulfur pesticides in environmental and beverage samples by gas chromatography with flame photometric detection.

    Science.gov (United States)

    Xiong, Jun; Hu, Bin

    2008-06-06

    Two methods based on hollow fiber liquid phase microextraction (HF-LPME) and dispersive liquid-liquid microextraction (DLLME), have been critically compared for the analysis of organosulfur pesticides (OSPs) in environmental and beverage samples by gas chromatography-flame photometric detection (GC-FPD). Experimental conditions including extraction solvent, solvent volume, extraction time, temperature and ionic strength have been investigated for both HF-LPME and DLLME. Under the optimal conditions, the limits of detection for the six target OSPs (malathion, chlorpyrifos, buprofezin, triazophos, carbosulfan and pyridaben) obtained by HF-LPME-GC-FPD and DLLME-GC-FPD were ranged from 1.16 microg/L to 48.48 microg/L and 0.21 microg/L to 3.05 microg/L, respectively. The relative standard deviations (RSDs, n=5) were in the range of 3.4-8.0% and 8.5-13.7%with the enrichment factors (EFs) of 27-530 and 176-946 folds for HF-LPME-GC-FPD and DLLME-GC-FPD, respectively. Both methods were found to be simple, fast, efficient, and inexpensive. Compared with HF-LPME, the advantages of DLLME technique were less extraction time, suitable for batches of samples pretreatment simultaneously, a higher extraction capacity when analyzing simple samples such as water samples. While for the analysis of complicated matrix samples such as soil and beverage samples, HF-LPME was demonstrated to be more robust and more suitable. Both methods were applied to the analysis of six OSPs in different waters, soil and beverage samples, and no target OSPs was found in these samples. For analysis of the spiked samples, the recovery of 81.7-114.4% with RSDs of 0.6-9.6% were obtained for HF-LPME, and the recovery of 78.5-117.2% with RSDs of 0.6-11.9% were obtained for DLLME.

  2. Design and implementation of an automated liquid-phase microextraction-chip system coupled on-line with high performance liquid chromatography.

    Science.gov (United States)

    Li, Bin; Petersen, Nickolaj Jacob; Payán, María D Ramos; Hansen, Steen Honoré; Pedersen-Bjergaard, Stig

    2014-03-01

    An automated liquid-phase microextraction (LPME) device in a chip format has been developed and coupled directly to high performance liquid chromatography (HPLC). A 10-port 2-position switching valve was used to hyphenate the LPME-chip with the HPLC autosampler, and to collect the extracted analytes, which then were delivered to the HPLC column. The LPME-chip-HPLC system was completely automated and controlled by the software of the HPLC instrument. The performance of this system was demonstrated with five alkaloids i.e. morphine, codeine, thebaine, papaverine, and noscapine as model analytes. The composition of the supported liquid membrane (SLM) and carrier was optimized in order to achieve reasonable extraction performance of all the five alkaloids. With 1-octanol as SLM solvent and with 25 mM sodium octanoate as anionic carrier, extraction recoveries for the different opium alkaloids ranged between 17% and 45%. The extraction provided high selectivity, and no interfering peaks in the chromatograms were observed when applied to human urine samples spiked with alkaloids. The detection limits using UV-detection were in the range of 1-21 ng/mL for the five opium alkaloids presented in water samples. The repeatability was within 5.0-10.8% (RSD). The membrane liquid in the LPME-chip was regenerated automatically between every third injection. With this procedure the liquid membrane in the LPME-chip was stable in 3-7 days depending on the complexity of sample solutions with continuous operation. With this LPME-chip-HPLC system, series of samples were automatically injected, extracted, separated, and detected without any operator interaction.

  3. Study of the mechanism of acetonitrile stacking and its application for directly combining liquid-phase microextraction with micellar electrokinetic chromatography.

    Science.gov (United States)

    Sun, Jingru; Feng, Jing; Shi, Ludi; Liu, Laping; He, Hui; Fan, Yingying; Hu, Shibin; Liu, Shuhui

    2016-08-26

    Acetonitrile stacking is an online concentration method that is distinctive due to its inclusion of a high proportion of organic solvent in sample matrices. We previously designed a universal methodology for the combination of liquid-phase microextraction (LPME) and capillary electrophoresis (CE) using acetonitrile stacking and micellar electrokinetic chromatography (MEKC) mode, thereby achieving large-volume injection of the diluted LPME extractant and the online concentration. In this report, the methodology was extended to the analysis of highly substituted hydrophobic chlorophenols in wines using diethyl carbonate as the extractant. Additionally, the mechanism of acetonitrile stacking was studied. The results indicated that the combination of LPME and MEKC exhibited good analytical performance: with ∼40-fold concentration by LPME, a 20-cm (33% of the total length) sample plug injection of an eight-fold dilution of diethyl carbonate with the organic solvent-saline solution produced enrichments higher by a factor of 260-791. Limits of qualification ranged from 5.5 to 16.0ng/mL. Acceptable reproducibilities of lower than 1.8% for migration time and 8.6% for peak areas were obtained. A dual stacking mechanism of acetonitrile stacking was revealed, involving transient isotachophoresis plus pH-junction stacking. The latter was associated with a pH shift induced by the presence of acetonitrile. The pseudo-stationary phase (Brij-35) played an important role in reducing the CE running time by weakening the isotachophoretic migration of the analyte ions following Cl(-) ions. The combination of acetonitrile stacking and nonionic micelle-based MEKC appears to be a perfect match for introducing water-immiscible LPME extractants into an aqueous CE system and can thus significantly expand the application of LPME-CE in green analytical chemistry.

  4. Determination of melamine in soil samples using surfactant-enhanced hollow fiber liquid phase microextraction followed by HPLC–UV using experimental design

    Directory of Open Access Journals (Sweden)

    Ali Sarafraz Yazdi

    2015-11-01

    Full Text Available Surfactant-enhanced hollow fiber liquid phase (SE-HF-LPME microextraction was applied for the extraction of melamine in conjunction with high performance liquid chromatography with UV detection (HPLC–UV. Sodium dodecyl sulfate (SDS was added firstly to the sample solution at pH 1.9 to form hydrophobic ion-pair with protonated melamine. Then the protonated melamine–dodecyl sulfate ion-pair (Mel–DS was extracted from aqueous phase into organic phase immobilized in the pores and lumen of the hollow fiber. After extraction, the analyte-enriched 1-octanol was withdrawn into the syringe and injected into the HPLC. Preliminary, one variable at a time method was applied to select the type of extraction solvent. Then, in screening step, the other variables that may affect the extraction efficiency of the analyte were studied using a fractional factorial design. In the next step, a central composite design was applied for optimization of the significant factors having positive effects on extraction efficiency. The optimum operational conditions included: sample volume, 5 mL; surfactant concentration, 1.5 mM; pH 1.9; stirring rate, 1500 rpm and extraction time, 60 min. Using the optimum conditions, the method was analytically evaluated. The detection limit, relative standard deviation and linear range were 0.005 μg mL−1, 4.0% (3 μg mL−1, n = 5 and 0.01–8 μg mL−1, respectively. The performance of the procedure in extraction of melamine from the soil samples was good according to its relative recoveries in different spiking levels (95–109%.

  5. Optimised extraction of heterocyclic aromatic amines from blood using hollow fibre membrane liquid-phase microextraction and triple quadrupole mass spectrometry.

    Science.gov (United States)

    Cooper, Kevin M; Jankhaikhot, Natcha; Cuskelly, Geraldine

    2014-09-05

    Heterocyclic aromatic amines (HCA) are carcinogenic mutagens formed during cooking of proteinaceous foods, particularly meat. To assist in the ongoing search for biomarkers of HCA exposure in blood, a method is described for the extraction from human plasma of the most abundant HCAs: 2-amino-1-methyl-6-phenylimidazo(4,5-b)pyridine (PhIP), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) and 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx) (and its isomer 7,8-DiMeIQx), using hollow fibre membrane liquid-phase microextraction. This technique employs 2.5cm lengths of porous polypropylene fibres impregnated with organic solvent to facilitate simultaneous extraction from an alkaline aqueous sample into a low volume acidic acceptor phase. This low cost protocol is extensively optimised for fibre length, extraction time, sample pH and volume. Detection is by UPLC-MS/MS using positive mode electrospray ionisation with a 3.4min runtime, with optimum peak shape, sensitivity and baseline separation being achieved at pH 9.5. To our knowledge this is the first description of HCA chromatography under alkaline conditions. Application of fixed ion ratio tolerances for confirmation of analyte identity is discussed. Assay precision is between 4.5 and 8.8% while lower limits of detection between 2 and 5pg/mL are below the concentrations postulated for acid-labile HCA-protein adducts in blood.

  6. Room temperature ionic liquids enhanced the speciation of Cr(VI) and Cr(III) by hollow fiber liquid phase microextraction combined with flame atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Chujie, E-mail: cjzeng@126.com [Department of Chemistry and Material, Yulin Normal College, Yulin, Guangxi 537000 (China); Lin, Yao; Zhou, Neng; Zheng, Jiaoting; Zhang, Wei [Department of Chemistry and Material, Yulin Normal College, Yulin, Guangxi 537000 (China)

    2012-10-30

    Highlights: Black-Right-Pointing-Pointer First reported enhancement effect of RTILs in HF-LPME for the speciation of chromium. Black-Right-Pointing-Pointer The addition of RTILs led to 3.5 times improvement of the sensitivity of Cr(VI). Black-Right-Pointing-Pointer The proposed method is a simplicity, sensitivity, low cost, green method. - Abstract: A new method for the speciation of Cr(VI) and Cr(III) based on enhancement effect of room temperature ionic liquids (RTILs) for hollow fiber liquid phase microextraction (HF-LPME) combined with flame atomic absorption spectrometry (FAAS) was developed. Room temperature ionic liquids (RTILs) and diethyldithiocarbamate (DDTC) were used enhancement reagents and chelating reagent, respectively. The addition of room temperature ionic liquids led to 3.5 times improvement in the determination of Cr(VI). In this method, Cr(VI) reacts with DDTC yielding a hydrophobic complex, which is subsequently extracted into the lumen of hollow fiber, whereas Cr(III) is remained in aqueous solutions. The extraction organic phase was injected into FAAS for the determination of Cr(VI). Total Cr concentration was determined after oxidizing Cr(III) to Cr(VI) in the presence of KMnO{sub 4} and using the extraction procedure mentioned above. Cr(III) was calculated by subtracting of Cr(VI) from the total Cr. Under optimized conditions, a detection limit of 0.7 ng mL{sup -1} and an enrichment factor of 175 were achieved. The relative standard deviation (RSD) was 4.9% for Cr(VI) (40 ng mL{sup -1}, n = 5). The proposed method was successfully applied to the speciation of chromium in natural water samples with satisfactory results.

  7. Development of a microfluidic-chip system for liquid-phase microextraction based on two immiscible organic solvents for the extraction and preconcentration of some hormonal drugs.

    Science.gov (United States)

    Asl, Yousef Abdossalami; Yamini, Yadollah; Seidi, Shahram

    2016-11-01

    In the present study, for the first time, an on-chip liquid phase microextraction (LPME) coupled with high performance liquid chromatography was introduced for the analysis of levonorgestrel (Levo), dydrogesterone (Dydo) and medroxyprogesterone (Medo) as the model analytes in biological samples. The chip-based LPME set-up was composed of two polymethyl methacrylate (PMMA) plates with microfabricated channels and a microporous membrane sandwiched between them to separate the sample solution and acceptor phase. These channels were used as a flow path for the sample solution and a thin compartment for the acceptor phase, respectively. In this system, two immiscible organic solvents were used as supported liquid membrane (SLM) and acceptor phase, respectively. During extraction, the model analytes in the sample solution were transported through the SLM (n-dodecane) into the acceptor organic solvent (methanol). The new set-up provided effective and reproducible extractions using low volumes of the sample solution. The effective parameters on the extraction efficiency of the model analytes were optimized using one variable at a time method. Under the optimized conditions, the new set-up provided good linearity in the range of 5.0-500µgL(-1) for the model analytes with the coefficients of determination (r(2)) higher than 0.9909. The relative standard deviations (RSDs%) and limits of detection (LODs) values were less than 6.5% (n=5) and 5.0µgL(-1), respectively. The preconcentration factors (PFs) were obtained using 1.0mL of the sample solution and 20.0µL of the acceptor solution higher than 19.9-fold. Finally, the proposed method was successfully applied for the extraction and determination of the model analytes in urine samples.

  8. Hydride generation coupled to microfunnel-assisted headspace liquid-phase microextraction for the determination of arsenic with UV-Vis spectrophotometry.

    Science.gov (United States)

    Hashemniaye-Torshizi, Reihaneh; Ashraf, Narges; Arbab-Zavar, Mohammad Hossein

    2014-12-01

    In this research, a microfunnel-assisted headspace liquid-phase microextraction technique has been used in combination with hydride generation to determine arsenic (As) by UV-Vis spectrophotometry. The method is based on the reduction of As to arsine (AsH3) in acidic media by sodium tetrahydroborate (NaBH4) followed by its subsequent reaction with silver diethyldithiocarbamate (AgDDC) to give an absorbing complex at 510 nm. The complexing reagent (AgDDC) has been dissolved in a 1:1 (by the volume ratio) mixture of chloroform/chlorobenzene microdroplet and exposed to the generated gaseous arsine via a reversed microfunnel in the headspace of the sample solution. Several operating parameters affecting the performance of the method have been examined and optimized. Acetonitrile solvent has been added to the working samples as a sensitivity enhancement agent. Under the optimized operating conditions, the detection limit has been measured to be 0.2 ng mL(-1) (based on 3sb/m criterion, n b = 8), and the calibration curve was linear in the range of 0.5-12 ng mL(-1). The relative standard deviation for eight replicate measurements was 1.9 %. Also, the effects of several potential interferences have been studied. The accuracy of the method was validated through the analysis of JR-1 geological standard reference material. The method has been successfully applied for the determination of arsenic in raw and spiked soft drink and water samples with the recoveries that ranged from 91 to 106 %.

  9. [Analysis of the preferred conformations and determination of the concentrations of ephedrine and pseudoephedrine based on hollow fiber liquid-phase microextraction].

    Science.gov (United States)

    Chen, Xuan; Bai, Xiaohong; Wang, Xiao; Wang, Jing; Bu, Wei

    2010-12-01

    The preferred conformations of the ephedrine and pseudoephedrine in Ephedra sinica Stapf and rat urine were analyzed by the hollow fiber liquid-phase microextraction (HF-LPME) and their extraction mechanisms were illuminated. The method of the separation of the ephedrine and pseudoephedrine and the determination of their concentrations with high performance liquid chromatography (HPLC) were established. The optimal experimental conditions were as follows: the organic phase carrier was the hollow fiber of polyvinylidene fluoride (MOF-503), organic solvent was n-hexanol, the extraction time was 35 min, the stirring rate was 1200 r/min, the sample phase was the NaOH solution (5 mol/L) of the analyte, the acceptor was 0.01 mol/L H2SO4 solution. The extracts were analyzed by HPLC. Under the optimal conditions, the method is convenient and highly sensitive. In Ephedra sinica Stapf, the linear ranges of ephedrine and pseudoephedrine were 5-100 microg/L, the detection limits were 1.9 microg/L and 1.2 microg/L and the enrichment factors were 38 and 61, respectively. The average recoveries of ephedrine and pseudoephedrine were 100.6% +/- 1.2% and 103.2% +/- 3.5%, respectively. In rat urine, their linear ranges were 100 - 5 x 10(4) microg/L, the detection limits were 30 microg/L and 42 microg/L and the enrichment factors were 20 and 17, respectively. In rat urine, their average recoveries were 108.4% +/- 4.4% and 106. 1% +/- 5.4%, respectively. The obtained results indicated that the method can be successfully applied for the extraction and determination of the ephedrine and pseudoephedrine in Ephedra sinica Stapf and rat urine.

  10. Determination of estrogenic compounds in milk and yogurt samples by hollow-fibre liquid-phase microextraction-gas chromatography-triple quadrupole mass spectrometry.

    Science.gov (United States)

    D'Orazio, Giovanni; Hernández-Borges, Javier; Herrera-Herrera, Antonio Vicente; Fanali, Salvatore; Rodríguez-Delgado, Miguel Ángel

    2016-10-01

    An environmentally friendly method based on hollow-fibre liquid-phase microextraction (HF-LPME) was developed for the extraction of selected estrogenic compounds (i.e. four natural sexual hormones: estrone, 17β-estradiol, 17α-estradiol and estriol; two exoestrogens: 17α-ethynylestradiol and 2-methoxyestradiol; two synthetic stilbenes: dienestrol and hexestrol; and five resorcylic acid lactones: zearalenone, α-zearalanol, β-zearalanol, α-zearalenol and β-zearalenol), from whole cow and semi-skimmed goat milk and whole natural yogurt. After the optimization of the sample preparation procedure, spiked extracts were derivatized to their trimethylsilyl products using N,O-bis(trimethylsilyl)trifluoroacetamide reagent and then analyzed by gas chromatography-tandem mass spectrometry (GC-MS/MS). Once optimum extraction conditions were established (protein precipitation with acetonitrile, extraction and the back-extraction in acetonitrile following the HF-LPME procedure), the method was validated and the calibration range, precision and accuracy were studied. The RSD values for the intra- and inter-day precision of the peak areas were in the range 0.65-9.69 and 1.00-11.47 %, respectively. The determination coefficients were higher than 0.991 for method calibration curves while LOD and LOQ values were between 0.06-2.55 and 0.16-6.11 μg/L for whole cow milk, 0.04-1.70 and 0.11-4.86 μg/L for semi-skimmed goat milk and 0.07-3.73 and 0.23-9.81 μg/L for natural yogurt, respectively. Finally, the accuracy and precision of the method were evaluated, obtaining a value in the range 84 81-119 % and RSD values lower than 20 % in all cases.

  11. Development of a method for the determination of cocaine, cocaethylene and norcocaine in human breast milk using liquid phase microextraction and gas chromatography-mass spectrometry.

    Science.gov (United States)

    Silveira, Gabriela de Oliveira; Belitsky, Íris Tikkanen; Loddi, Silvana; Rodrigues de Oliveira, Carolina Dizioli; Zucoloto, Alexandre Dias; Fruchtengarten, Ligia Veras Gimenez; Yonamine, Mauricio

    2016-08-01

    Most licit and illicit substances consumed by the nursing mother might be excreted in breast milk, which may cause potential short and long term harmful effects for the breastfed infant. The extraction of substances from this matrix represents an analytical challenge due to its high protein and fat content as well as the fact that its composition changes during postpartum period. The aim of the present study was to develop a liquid phase microextraction (LPME) method for detection of the active substances: cocaine (COC), cocaethylene (CE) and norcocaine (NCOC) in human breast milk using gas chromatography-mass spectrometry (GC-MS). Validation was performed working on spiked human breast milk samples. The limits of detection (LOD) and quantification (LOQ) were of 6 and 12ng/mL, respectively, for all analytes. Calibration curves were linear over a concentration range of 12.0ng/mL-1000ng/mL (r(2)=0.99). No interferences were noticed at the retention times of interest. Within-run and between-run precision was always less or equal to 15 as % relative standard deviation, and bias ranged from 3 to 18%. Forty six milk samples were analyzed. Only one sample was confirmed to be COC positive (138ng/mL) and another one presented COC concentration near the LOD (6ng/mL). This method has shown to be a reliable alternative for the determination of cocaine, cocaethylene and norcocaine in human breast milk in the fields of clinical and forensic toxicology. LPME extraction procedure demonstrated to be a rather promising, low cost and environmental-friendly technique for the purpose of this study.

  12. Combination of hollow fiber liquid phase microextraction followed by HPLC-DAD and multivariate curve resolution to determine antibacterial residues in foods of animal origin.

    Science.gov (United States)

    Tajabadi, Fateme; Ghambarian, Mahnaz; Yamini, Yadollah; Yazdanfar, Najmeh

    2016-11-01

    In the present research, a carrier mediated hollow fiber based liquid-phase microextraction approach (HF-LPME) prior to high performance liquid chromatography-diode array detection (HPLC-DAD) was developed for the simultaneous determination of the antibacterial residues of four tetracyclines (TCs) and five quinolones (QNs), which are commonly used as veterinary medicines. In order to obtain high extraction efficiency, the parameters affecting HF-LPME were optimized using a three-factor and three-level Box-Behnken design under response surface methodology. This method was validated according to the recommendations of the Food and Drug Administration (FDA), and, for the first time, successfully applied to a wide range of animal source food samples such as fish, milk, and honey as well as the liver and muscles of lamb and chicken. Analytical performance was determined in terms of linearity, intra- and inter-assay precision, detection and quantification limits, matrix effect, accuracy, and drug stability in real samples. Detection and quantitation limits for the different antibiotics ranged between 0.5-20ngg(-1) and 1.25-40ngg(-1), respectively. Intra and inter-day repeatability, expressed as the relative standard deviation, were in the ranges of 3.4-10.7% and 5.0-11.5%, respectively. The procedure allows good preconcentration factors of 175-700. The results of the validation process proved that the method is suitable for determining TCs and QNs residues in surveillance programs. Finally, the applicability of the proposed method was successfully confirmed by the extraction and determination of nine antibiotics in various animal source food samples. The importance of this methodology relies on the combination of HF-LPME/HPLC-DAD second-order data with multivariate curve resolution-alternative least squares (MCR-ALS) algorithm, which improves the resolution of some overlapped chromatograms and, hence, increases the accuracy and repeatability of drug determination.

  13. The Application of Ionic Liquid-liquid Phase Microextraction in the Analysis of Environmental Contaminants%离子液体-液相微萃取法在环境污染物分析中的应用

    Institute of Scientific and Technical Information of China (English)

    唐倩倩; 相秉仁

    2012-01-01

    With the development of liquid-phase microextraction technology, in recent years, ionic liquids as extractant in liquid microextraction technology have been widely used for the analysis of environmental pollutants. This paper provides a brief overview of ionic liquids in three important sample-preparation techniques, namely, ionic liquid single drop microextraction, ionic liquid-hollow fiber membrane microextraction, and ionic liquid-liquid dispersions microextraction, and highlights the application in the analysis of environmental contaminants.%随着溶剂微萃取技术的发展,近年来,以离子液体为萃取剂的液相微萃取技术在环境污染物的检测中已经得到大量应用.该文对离子液体-液相微萃取的三种主要模式:离子液体-单液滴微萃取,离子液体-中空纤维膜微萃取,离子液体-分散液液微萃取进行了综述,并着重介绍了其在环境污染物分析中的应用.

  14. 中空纤维膜液相微萃取技术及其应用进展%Hollow fiber membrane liquid-phase microextraction technique and its application

    Institute of Scientific and Technical Information of China (English)

    宋林; 乐健; 洪战英

    2014-01-01

    Hollow fiber membrane liquid-phase microextraction technique is a kind of environment friendly sample pretreatment technique,which integrates sampling,extraction and concentration into one.In this paper,the structure characteristics of porous hollow fiber membrane,the microextraction installation,the extraction pattern,the applications of hollow fiber membrane liquid-phase microextraction in different samples,such as environmental samples and biological body fluid were introduced,and the extraction influential factors were analyzed as well.%中空纤维膜液相微萃取技术是一种集采样、萃取和浓缩于一体,环境友好的样品前处理技术.本文介绍了多孔中空纤维膜的结构特点、微萃取装置以及萃取模式,对影响其萃取效果的因素加以分析,同时介绍了中空纤维膜液相微萃取技术在环境和生物体液等样品中的应用.

  15. Extraction and preconcentration of tylosin from milk samples through functionalized TiO₂ nanoparticles reinforced with a hollow fiber membrane as a novel solid/liquid-phase microextraction technique.

    Science.gov (United States)

    Sehati, Negar; Dalali, Nasser; Soltanpour, Shahla; Dorraji, Mir Saeed Seyed

    2014-08-01

    The aim of this study was to introduce a novel, simple, and highly sensitive preparation method for determination of tylosin in different milk samples. In the so-called functionalized TiO2 hollow fiber solid/liquid-phase microextraction method, the acceptor phase is functionalized TiO2 nanoparticles that are dispersed in the organic solvent and held in the pores and lumen of a porous polypropylene hollow fiber membrane. An effective functionalization of TiO2 nanoparticles has been done in the presence of aqueous H2 O2 and a mild acidic ambient under UV irradiation. This novel extraction method showed excellent extraction efficiency and a high enrichment factor (540.2) in comparison with conventional hollow fiber liquid-phase microextraction. All the experiments were monitored at λmax = 284 nm using a simple double beam UV-visible spectrophotometer. A Taguchi orthogonal array experimental design with an OA16 (4(5) ) matrix was employed to optimize the factors affecting the efficiency of hollow fiber solid/liquid-phase microextraction such as pH, stirring rate, salt addition, extraction time, and the volume of donor phase. This developed method was successfully applied for the separation and determination of tylosin in milk samples with a linear concentration range of 0.51-7000 μg/L (r(2) = 0.991) and 0.21 μg/L as the limit of detection. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Energy Technology Data Exchange (ETDEWEB)

    Bharat L. Bhatt

    1997-05-01

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

  17. Application of modified hollow fiber liquid phase microextraction in conjunction with chromatography-electron capture detection for quantification of acrylamide in waste water samples at ultra-trace levels.

    Science.gov (United States)

    Sobhi, Hamid Reza; Ghambarian, Mahnaz; Behbahani, Mohammad; Esrafili, Ali

    2017-03-03

    Herein, a simple and sensitive method was successfully developed for the extraction and quantification of acrylamide in water samples. Initially, acrylamide was derivatized through a bromination process. Subsequently, a modified hollow-fiber liquid-phase microextraction was applied for the extraction of the brominated acrylamide from a 10-ml portion of an aqueous sample. Briefly, in this method, the derivatized acrylamide (2,3-dibromopropionamide) was extracted from the aqueous sample into a thin layer of an organic solvent sustained in pores of a porous hollow fiber. Then, it was back-extracted using a small volume of organic acceptor solution (acetonitril, 25μl) located inside the lumen of the hollow fiber followed by gas chromatography-electron capture detection (GC-ECD). The optimal conditions were examined for the extraction of the analyte such as: the organic solvent: dihexyl ether+10% tri-n-octyl phosphine oxide; stirring rate: 750rpm; no salt addition and 30min extraction time. These optimal extraction conditions allowed excellent enrichment factor values for the method. Enrichment factor, detection limit (S/N=3) and dynamic linear range of 60, 2ngL(-1) and 50-1000ngL(-1) to be determined for the analyte. The relative standard deviations (RSD%) representing precision of the method were in the range of 2.2-5.8 based on the average of three measurements. Accuracy of the method was tested by the relative recovery experiments on spiked samples, with results ranging from 93 to 108%. Finally, the method proved to be simple, rapid, and cost-effective for routine screen of acrylamide-contaminated highly-complicated untreated waste water samples. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Computational Fluid Dynamics Simulation of Liquid-Phase FCC Diesel Hydrotreating in Tubular Reactor

    Institute of Scientific and Technical Information of China (English)

    Li Hua; Liu Ningqiang; Zeng Zhiyu; Zou Ying; Wang Jiming

    2015-01-01

    The computational lfuid dynamics (CFD) code, FLUENT, was used to simulate the liquid-phase FCC diesel hy-drotreating tubular reactor with a ceramic membrane tube dispenser. The chemical reaction and reaction heat were added to the model by user-deifned function (UDF), showing the distribution of temperature and content of sulifdes, nitrides, bicyclic aromatics and monocyclic aromatics in different parts of the reaction bed. When the pressure was 6.5 MPa, the amount of mixing hydrogen was 0.84% (m), the space velocity was 2 h-1 and the inlet temperature was 633K, the temperature reached a maximum at a height of 0.15 m, and the range of radial temperature reached its maximum (2.5 K) at a height of 0.15 m. It indicated that the proper ratio of height to diameter of catalyst bed in the tubular reactor was 5-6. The increase of inlet temperature, the mixing hydrogen and the decrease of space velocity led to the decrease in the content of bicyclic aromatics, sulifdes and nitrides, and the increase in monocyclic aromatics content, while the high temperature increased. The results were in good agreement with experimental data, indicating to the high accuracy of the model.

  19. Liquid-Phase Exfoliation of Phosphorene: Design Rules from Molecular Dynamics Simulations.

    Science.gov (United States)

    Sresht, Vishnu; Pádua, Agílio A H; Blankschtein, Daniel

    2015-08-25

    The liquid-phase exfoliation of phosphorene, the two-dimensional derivative of black phosphorus, in the solvents dimethyl sulfoxide (DMSO), dimethylformamide (DMF), isopropyl alcohol, N-methyl-2-pyrrolidone, and N-cyclohexyl-2-pyrrolidone is investigated using three molecular-scale "computer experiments". We modeled solvent-phosphorene interactions using an atomistic force field, based on ab initio calculations and lattice dynamics, that accurately reproduces experimental mechanical properties. We probed solvent molecule ordering at phosphorene/solvent interfaces and discovered that planar molecules such as N-methyl-2-pyrrolidone preferentially orient parallel to the interface. We subsequently measured the energy required to peel a single phosphorene monolayer from a stack of black phosphorus and analyzed the role of "wedges" of solvent molecules intercalating between phosphorene sheets in initiating exfoliation. The exfoliation efficacy of a solvent is enhanced when either molecular planarity "sharpens" this molecular wedge or strong phosphorene-solvent adhesion stabilizes the newly exposed phosphorene surfaces. Finally, we examined the colloidal stability of exfoliated flakes by simulating their aggregation and showed that dispersion is favored when the cohesive energy between the molecules in the solvent monolayer confined between the phosphorene sheets is high (as with DMSO) and is hindered when the adhesion between these molecules and phosphorene is strong; the molecular planarity in solvents like DMF enhances the cohesive energy. Our results are consistent with, and provide a molecular context for, experimental exfoliation studies of phosphorene and other layered solids, and our molecular insights into the significant role of solvent molecular geometry and ordering should complement prevalent solubility-parameter-based approaches in establishing design rules for effective nanomaterial exfoliation media.

  20. Unusual vortex dynamics in the quantum-liquid phase of a-MoSi1− films

    Indian Academy of Sciences (India)

    S Okuma

    2006-01-01

    We find the unusual vortex dynamics in the low-temperature liquid phase of amorphous MoSi1− films by measuring the fluctuating component of the flux-flow voltage () about the average voltage. For the thick film, in which the quantum-vortexliquid (QVL) phase has been well-determined in the field–temperature plane, () originating from the vortex motion is clearly visible in the QVL phase, where the distribution of () is anomalously asymmetric, implying large velocity and/or number fluctuations of driven vortices. For the thin film, in which the QVL phase has not been determined from the static transport measurements, similar unusual vortex motion is observed in nearly the same reduced-temperature regime. We suggest that vortex dynamics in the low-temperature liquid phase of thick and thin films is dominated by common physical mechanisms related to quantum-fluctuation effects.

  1. Vibrational circular dichroism from ab initio molecular dynamics and nuclear velocity perturbation theory in the liquid phase.

    Science.gov (United States)

    Scherrer, Arne; Vuilleumier, Rodolphe; Sebastiani, Daniel

    2016-08-28

    We report the first fully ab initio calculation of dynamical vibrational circular dichroism spectra in the liquid phase using nuclear velocity perturbation theory (NVPT) derived electronic currents. Our approach is rigorous and general and thus capable of treating weak interactions of chiral molecules as, e.g., chirality transfer from a chiral molecule to an achiral solvent. We use an implementation of the NVPT that is projected along the dynamics to obtain the current and magnetic dipole moments required for accurate intensities. The gauge problem in the liquid phase is resolved in a twofold approach. The electronic expectation values are evaluated in a distributed origin gauge, employing maximally localized Wannier orbitals. In a second step, the gauge invariant spectrum is obtained in terms of a scaled molecular moments, which allows to systematically include solvent effects while keeping a significant signal-to-noise ratio. We give a thorough analysis and discussion of this choice of gauge for the liquid phase. At low temperatures, we recover the established double harmonic approximation. The methodology is applied to chiral molecules ((S)-d2-oxirane and (R)-propylene-oxide) in the gas phase and in solution. We find an excellent agreement with the theoretical and experimental references, including the emergence of signals due to chirality transfer from the solute to the (achiral) solvent.

  2. Vibrational circular dichroism from ab initio molecular dynamics and nuclear velocity perturbation theory in the liquid phase

    Science.gov (United States)

    Scherrer, Arne; Vuilleumier, Rodolphe; Sebastiani, Daniel

    2016-08-01

    We report the first fully ab initio calculation of dynamical vibrational circular dichroism spectra in the liquid phase using nuclear velocity perturbation theory (NVPT) derived electronic currents. Our approach is rigorous and general and thus capable of treating weak interactions of chiral molecules as, e.g., chirality transfer from a chiral molecule to an achiral solvent. We use an implementation of the NVPT that is projected along the dynamics to obtain the current and magnetic dipole moments required for accurate intensities. The gauge problem in the liquid phase is resolved in a twofold approach. The electronic expectation values are evaluated in a distributed origin gauge, employing maximally localized Wannier orbitals. In a second step, the gauge invariant spectrum is obtained in terms of a scaled molecular moments, which allows to systematically include solvent effects while keeping a significant signal-to-noise ratio. We give a thorough analysis and discussion of this choice of gauge for the liquid phase. At low temperatures, we recover the established double harmonic approximation. The methodology is applied to chiral molecules ((S)-d2-oxirane and (R)-propylene-oxide) in the gas phase and in solution. We find an excellent agreement with the theoretical and experimental references, including the emergence of signals due to chirality transfer from the solute to the (achiral) solvent.

  3. 液相微萃取技术在生物样品药物检测中的应用%Application of liquid phase microextraction on drugs analysis in biological samples

    Institute of Scientific and Technical Information of China (English)

    杨新磊; 罗明标; 唐毓萍; 丁健桦

    2007-01-01

    本文详细介绍了一种新型的样品前处理技术--液相微萃取(liquid phase microextraction,LPME)技术的发展概况和当前国内外所采用的主要萃取模型及其基本原理,讨论了可能影响其萃取效果的实验参数及其优化方法.综述了这种新型样品前处理技术在生物样品药物检测中的应用状况.

  4. The Study of the Liquid Phase Micro-extraction Technology in the Pre-treatment of Geological Samples%液相微萃取技术在地质样品前处理中的研究

    Institute of Scientific and Technical Information of China (English)

    卢文文; 黄国林; 金超

    2012-01-01

    文章论述了地质样品的前处理技术,重点评述了近年在分析化学领域发展较快的液相微萃取技术。该技术富集倍数高、有机溶剂用量非常少,是一种环境友好的样品前处理新技术。%The paper discussed the pre-treatment technology used in geological samples, and focus were reviewed the faster development of liquid phase micro-extraction technology in the field of analytical chemistry in recent years. There is the high enrichment factor in this technology and the organic solvent is very small, it is a new pre-treatment technology that is friendly to the environment.

  5. Research progress of liquid phase micro-extraction technology in the field of drug analysis%液相微萃取技术在毒品分析领域的研究进展

    Institute of Scientific and Technical Information of China (English)

    王萌; 郑珲; 翟晚枫; 张春水

    2012-01-01

    This paper gives a review of the research progress in the field of forensic science drug analysis at home and abroad in recent years. It gives a comprehensive summary of modes, principles, influencing factors and characteristics of liquid phase micro-extraction technology, hoping to provide some help for forensic science drug analysis and handling cases.%本文综述了近年来液相微萃取技术在国内外法庭科学毒品分析领域的研究应用进展,对液相微萃取技术的不同实现模式及对应的原理、影响因素、方法特点进行了系统总结.以期能够为法庭科学领域的毒品研究和办案提供一些帮助.

  6. Furanic compounds and furfural in different coffee products by headspace liquid-phase micro-extraction followed by gas chromatography-mass spectrometry: survey and effect of brewing procedures.

    Science.gov (United States)

    Chaichi, Maryam; Ghasemzadeh-Mohammadi, Vahid; Hashemi, Maryam; Mohammadi, Abdorreza

    2015-01-01

    In this study, the levels of furan, 2-methylfuran, 2,5-dimethylfuran, vinyl furan, 2-methoxymethyl-furan and furfural in different coffee products were evaluated. Simultaneous determination of these six furanic compounds was performed by a head space liquid-phase micro-extraction (HS-LPME) method. A total of 67 coffee powder samples were analysed. The effects of boiling and espresso-making procedures on the levels of furanic compounds were investigated. The results showed that different types of coffee samples contained different concentrations of furanic compounds, due to the various processing conditions such as temperature, degree of roasting and fineness of grind. Among the different coffee samples, the highest level of furan (6320 µg kg⁻¹) was detected in ground coffee, while coffee-mix samples showed the lowest furan concentration (10 µg kg⁻¹). Levels in brewed coffees indicated that, except for furfural, brewing by an espresso machine caused significant loss of furanic compounds.

  7. Microextração em fase líquida (LPME: fundamentos da técnica e aplicações na análise de fármacos em fluidos biológicos Liquid-phase microextraction (LPME: fundamentals and applications to the analysis of drugs in biological samples

    Directory of Open Access Journals (Sweden)

    Anderson Rodrigo Moraes de Oliveira

    2008-01-01

    Full Text Available The analysis of drugs and metabolites in biological fluids usually requires extraction procedures to achieve sample clean-up and analyte preconcentration. Commonly, extraction procedures are performed using liquid-liquid extraction or solid-phase extraction. Nevertheless, these extraction techniques are considered to be time-consuming and require a large amount of organic solvents. On this basis, microextraction techniques have been developed. Among them, liquid-phase microextraction has been standing out. This review describes the liquid-phase microextraction technique based on hollow fibers as a novel and promising alternative in sample preparation prior to chromatographic or electrophoretic analysis. The basic concepts related to this technique and its applicability in extraction of drugs are discussed.

  8. Simultaneous extraction and determination of albendazole and triclabendazole by a novel syringe to syringe dispersive liquid phase microextraction-solidified floating organic drop combined with high performance liquid chromatography.

    Science.gov (United States)

    Asadi, Mohammad; Dadfarnia, Shayessteh; Haji Shabani, Ali Mohammad

    2016-08-17

    A syringe to syringe dispersive liquid phase microextraction-solidified floating organic drop was introduced and used for the simultaneous extraction of trace amounts of albendazole and triclabendazole from different matrices. The extracted analytes were determined by high performance liquid chromatography along with fluorescence detection. The analytical parameters affecting the microextraction efficiency including the nature and volume of the extraction solvent, sample volume, sample pH, ionic strength and the cycles of extraction were optimized. The calibration curves were linear in the range of 0.1-30.0 μg L(-1) and 0.2-30.0 μg L(-1) with determination coefficients of 0.9999 and 0.9998 for albendazole and triclabendazole respectively. The detection limits defined as three folds of the signal to noise ratio were found to be 0.02 μg L(-1) for albendazole and 0.06 μg L(-1) for triclabendazole. The inter-day and intra-day precision (RSD%) for both analytes at three concentration levels (0.5, 2.0 and 10.0 μg L(-1)) were in the range of 6.3-10.1% and 5.0-7.5% respectively. The developed method was successfully applied to determine albendazole and triclabendazole in water, cow milk, honey, and urine samples.

  9. Combination of hollow fiber-based liquid-phase microextraction with sweeping techniques in micellar electrokinetic chromatography for the determination of Strychnos alkaloids in human urine

    Institute of Scientific and Technical Information of China (English)

    Xiao Huan Zang; Cai Rui Li; Qiu Hua Wu; Chun Wang; Dan Dan Han; Zhi Wang

    2007-01-01

    A new method for the enrichment of Strychnos alkaloids in biological samples via liquid-phase rnicroextraction (LPME) based on porous polypropylene hollow fibers in combination with on-line sweeping in micellar electrokinetic chromatography was developed. The calibration curve was linear over the range of 20-200 ng mL-1 for both strychnine and brucine in human urine sample. The detection limits (S/N = 3:1) for strychnine and brucine were 1 ng mL-1 and 2 ng mL-1, respectively. The LPME-sweeping method has been successfully applied to the analysis of strychnine and brucine in real urine samples.

  10. Hollow fiber based liquid-phase microextraction for the determination of mercury traces in water samples by electrothermal atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Garcia, Ignacio; Rivas, Ricardo E. [Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence ' Campus Mare Nostrum' , University of Murcia, E-30071 Murcia (Spain); Hernandez-Cordoba, Manuel, E-mail: hcordoba@um.es [Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence ' Campus Mare Nostrum' , University of Murcia, E-30071 Murcia (Spain)

    2012-09-19

    Highlight: Black-Right-Pointing-Pointer Hg (II) traces are preconcentrated by means of a three-phase liquid microextraction system. Black-Right-Pointing-Pointer PAN and ammonium iodide are used in the donor and acceptor phase, respectively. Black-Right-Pointing-Pointer Hollow-fiber pores are continuously fed with toluene placed in the lumen. Black-Right-Pointing-Pointer Mercuric ions can be measured in waters below the {mu}g L{sup -1} level. - Abstract: A three-phase liquid microextraction procedure for the determination of mercury at low concentrations is discussed. To the aqueous sample placed at pH 7 by means of a phosphate buffer, 0.002% (m/v) 1-(2-pyridylazo)-2-naphthol (PAN) is incorporated, and the mixture submitted to microextraction with a hollow-fiber impregnated with toluene and whose lumen contains a 0.05 mol L{sup -1} ammonium iodide solution. The final measurement of the extract is carried out by electrothermal atomic absorption spectrometry (300 Degree-Sign C and 1100 Degree-Sign C for the calcination and atomization temperatures, respectively). The pyrolytic graphite atomizer is coated electrolytically with palladium. An enrichment factor of 270, which results in a 0.06 {mu}g L{sup -1} mercury for the detection limit is obtained. The relative standard deviation at the 1 {mu}g L{sup -1} mercury level is 3.2% (n = 5). The reliability of the procedure is verified by analyzing waters as well as six certified reference materials.

  11. 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.

  12. Development of garlic bioactive compounds analytical methodology based on liquid phase microextraction using response surface design. Implications for dual analysis: Cooked and biological fluids samples.

    Science.gov (United States)

    Ramirez, Daniela Andrea; Locatelli, Daniela Ana; Torres-Palazzolo, Carolina Andrea; Altamirano, Jorgelina Cecilia; Camargo, Alejandra Beatriz

    2017-01-15

    Organosulphur compounds (OSCs) present in garlic (Allium sativum L.) are responsible of several biological properties. Functional foods researches indicate the importance of quantifying these compounds in food matrices and biological fluids. For this purpose, this paper introduces a novel methodology based on dispersive liquid-liquid microextraction (DLLME) coupled to high performance liquid chromatography with ultraviolet detector (HPLC-UV) for the extraction and determination of organosulphur compounds in different matrices. The target analytes were allicin, (E)- and (Z)-ajoene, 2-vinyl-4H-1,2-dithiin (2-VD), diallyl sulphide (DAS) and diallyl disulphide (DADS). The microextraction technique was optimized using an experimental design, and the analytical performance was evaluated under optimum conditions. The desirability function presented an optimal value for 600μL of chloroform as extraction solvent using acetonitrile as dispersant. The method proved to be reliable, precise and accurate. It was successfully applied to determine OSCs in cooked garlic samples as well as blood plasma and digestive fluids. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Temperature-controlled ionic liquid dispersive liquid phase microextraction combined with ultra-high-pressure liquid chromatography for the rapid determination of triclosan,triclocarban and methyl-triclosan in aqueous samples

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    As extraction solvents,ionic liquids have green characteristics.In this study,an environmentally benign analytical method termed temperature-controlled ionic liquid dispersive liquid phase microextraction (TIL-DLME) combined with ultra-highpressure liquid chromatography (UHPLC)-tunable ultraviolet detection (TUV) was developed for the pre-concentration and determination of triclosan (TCS),triclocarban (TCC) and methyl-triclosan (M-TCS) in water samples.Significant parameters that may affect extraction efficiencies were examined and optimized,including the types and amount of ionic liquids,volume of the diluent,heating temperature,cooling time,salt effect and pH value.Under the optimum conditions,linearity of the method was observed in the ranges of 0.0100-100 μgL-1 for TCS and M-TCS,and 0.00500-50.0 μgL-1 for TCC with correlation coefficients (r2) > 0.9903.The limits of detection (LODs) ranged from 1.15 to 5.33 ngL-1.TCS in domestic water and TCC in reclaimed water were detected at the concentrations of 1.01 and 0.126 μgL-1,respectively.The spiked recoveries of the three target compounds in reclaimed water,irrigating water,waste water and domestic water samples were obtained in the ranges of 68.4%-71.9%,61.6%-87.8%,58.9%-74.9% and 64.9%-92.4%,respectively.Compared with the previous dispersive liquid-liquid microextraction method (DLLME) about the determination of TCS,TCC and M-TCS,this method is not only more environmentally friendly but also more sensitive.

  14. Carbon nanotube reinforced hollow fiber solid/liquid phase microextraction: a novel extraction technique for the measurement of caffeic acid in Echinacea purpurea herbal extracts combined with high-performance liquid chromatography.

    Science.gov (United States)

    Es'haghi, Zarrin; Golsefidi, Mazyar Ahmadi; Saify, Ali; Tanha, Ali Akbar; Rezaeifar, Zohre; Alian-Nezhadi, Zahra

    2010-04-23

    A new design of hollow fiber solid-liquid phase microextraction (HF-SLPME) was developed for the determination of caffeic acid in medicinal plants samples as Echinacea purpure. The membrane extraction with sorbent interface used in this research is a three-phase supported liquid membrane consisting of an aqueous (donor phase), organic solvent/nano sorbent (membrane) and aqueous (acceptor phase) system operated in direct immersion sampling mode. The multi-walled carbon nanotube dispersed in the organic solvent is held in the pores of a porous membrane supported by capillary forces and sonification. It is in contact with two aqueous phases: the donor phase, which is the aqueous sample, and the acceptor phase, usually an aqueous buffer. All microextraction experiments were supported using an Accurel Q3/2 polypropylene hollow fiber membrane (600 microm I.D., 200 microm wall thicknesses, and 0.2 microm pore size). The experimental setup is very simple and highly affordable. The hollow fiber is disposable, so single use of the fiber reduces the risk of cross-contamination and carry-over problems. The proposed method allows the very effective and enriched recuperation of an acidic analyte into one single extract. In order to obtain high enrichment and extraction efficiency of the analyte using this novel technique, the main parameters were optimized. Under the optimized extraction conditions, the method showed good linearity (0.0001-50 microg/L), repeatability, low limits of detection (0.00005 microg/L) and excellent enrichment (EF=2108). Copyright 2010 Elsevier B.V. All rights reserved.

  15. Fiber-based liquid-phase micro-extraction of mebeverine enantiomers followed by chiral high-performance liquid chromatography analysis and its application to pharmacokinetics study in rat plasma.

    Science.gov (United States)

    Hatami, Mehdi; Farhadi, Khalil; Tukmechi, Amir

    2012-08-01

    The applicability of two-phase liquid-phase micro-extraction (LPME) in porous hollow polypropylene fiber for the sample preparation and the stereoselective pharmacokinetics of mebeverine (MEB) enantiomers (an antispasmodic drug) in rat after intramuscular administration were studied. Plasma was assayed for MEB enantiomer concentrations using stereospecific high-performance liquid chromatography with ultraviolet detection after a simple, inexpensive, and efficient preconcentration and clean-up hollow fiber-based LPME. Under optimized micro-extraction conditions, MEB enantiomers were extracted with 25 µl of 1-octanol within a lumen of a hollow fiber from 0.5 ml of plasma previously diluted with 4.5 ml alkalized water (pH 10). The chromatographic analysis was carried out through chiral liquid chromatography using a DELTA S column and hexane-isopropyl alcohol (85:15 v/v) containing 0.2% triethylamine as mobile phase. The mean recoveries of (+)-MEB and (-)-MEB were 75.5% and 71.0%, respectively. The limit of detection (LOD) was 3.0 ng/ml with linear response over the concentration range of 10-2500 ng/ml with correlation coefficient higher than 0.993 for both enantiomers. The pharmacokinetic studies showed that the mean plasma levels of (+)-MEB were higher than those of (-)-MEB at almost all time points. Also, (+)-MEB exhibited greater t(max) (peak time in concentration-time profile), C(max) (peak concentration in concentration-time profile), t(1/2) (elimination half-life), and AUC(0-240 min) (area under the curve for concentration versus time) and smaller CL (clearance) and V(d) (apparent distribution volume) than its antipode. The obtained results implied that the absorption, distribution, and elimination of (-)-MEB were more rapid than those of (+)-MEB and there were stereoselective differences in pharmacokinetics.

  16. 中空纤维液相微萃取技术及其在食品有机污染物检测中的应用%Hollow fiber liquid phase microextraction technology and its application in the detection of organic pollutants in food

    Institute of Scientific and Technical Information of China (English)

    朱艳梅; 焦必宁

    2013-01-01

    As a kind of environmental friendly new sample preparation technology,hollow fiber liquid phase microextraction(HF-LPME),integrates extraction,purification and enrichment as a whole.This technology has the characteristic of simple device,low cost,easily combined with a variety of instruments spectrometry,low detection limit,higher recovery,and so on.The application of hollow fiber liquid phase microextraction technology is less in China.This paper reviewed the device,the pattern,the principle of hollow fiber liquid phase microextraction and its application in the detection of organic pollutants in food.%中空纤维液相微萃取作为一种环境友好的新型样品前处理技术,集萃取、净化、浓缩为一体,具有装置简单,成本低,易于与多种仪器联用,富集倍数、检测限低等特点.中空纤维液相微萃取技术在国内的应用还较少.本文综述了中空纤维液相微萃取的装置、模式、原理及在食品有机污染物检测中的应用.

  17. Deep eutectic liquid organic salt as a new solvent for liquid-phase microextraction and its application in ligandless extraction and preconcentraion of lead and cadmium in edible oils.

    Science.gov (United States)

    Karimi, Mehdi; Dadfarnia, Shayessteh; Shabani, Ali Mohammad Haji; Tamaddon, Fatemeh; Azadi, Davood

    2015-11-01

    Deep eutectic liquid organic salt was used as the solvent and a liquid phase microextraction (DES-LPME) combined with electrothermal atomic absorption spectrometry (ETAAS) was developed for separation, preconcentration and determination of lead and cadmium in edible oils. A 4:1 mixture of deep eutectic solvent and 2% nitric acid (200 µL) was added to an oil sample. The mixture was vortexed and transferred into a water bath at 50 °C and stirred for 5 minutes. After the extraction was completed, the phases were separated by centrifugation, and the enriched analytes in the deep eutectic solvent phase were determined by ETAAS. Under optimized extraction conditions and for an oil sample of 28 g, enhancement factors of 198 and 195 and limits of detection (defined as 3 Sb/m) of 8 and 0. 2 ng kg(-1) were achieved for lead and cadmium respectively. The method was successfully applied to the determination of lead and cadmium in various edible oils.

  18. Three-phase molecularly imprinted sol-gel based hollow fiber liquid-phase microextraction combined with liquid chromatography-tandem mass spectrometry for enrichment and selective determination of a tentative lung cancer biomarker.

    Science.gov (United States)

    Moein, Mohammad Mahdi; Javanbakht, Mehran; Karimi, Mohammad; Akbari-Adergani, Behrouz; Abdel-Rehim, Mohamed

    2015-07-15

    In the present study, the modification of a polysulfone hollow fiber membrane with in situ molecularly imprinted sol-gel process (as a novel and one-step method) was prepared and investigated. 3-(propylmethacrylate)trimethoxysilane (3PMTMOS) as an inorganic precursor was used for preparation of molecularly imprinted sol-gel. The modified molecularly imprinted sol-gel hollow fiber membrane (MSHM) was used for the liquid-phase microextraction (LPME) of hippuric acid (HA) in human plasma and urine samples. MSHM as a selective, robust, and durable tool was used for at least 50 extractions without significant decrease in the extraction efficiency. The non-molecularly imprinted sol-gel hollow fiber membrane (NSHM) as blank hollow fiber membrane was prepared by the same process, only without HA. To achieve the best condition, influential parameters on the extraction efficiency were thoroughly investigated. The capability of this robust, green, and simple method for extraction of HA was successfully accomplished with LC/MS/MS. The limits of detection (LOD) and quantification (LOQ) in human plasma and urine samples were 0.3 and 1.0nmolL(-1), respectively. The standard calibration curves were obtained within the concentration range 1-2000nmolL(-1) for HA in human plasma and urine. The coefficients of determination (r(2)) were ≥0.998. The obtained data exhibited recoveries were higher than 89% for the extraction of HA in human plasma and urine samples.

  19. Application of ionic liquid-based dispersive liquid phase microextraction for highly sensitive simultaneous determination of three endocrine disrupting compounds in food packaging.

    Science.gov (United States)

    Wang, Lingling; Zhang, Danfeng; Xu, Xu; Zhang, Lei

    2016-04-15

    Ionic liquid (IL) dispersive liquid-liquid microextraction (DLLME) method was successfully developed for extracting three endocrine disrupting compounds (EDCs) (bisphenol A, bisphenol AF and bisphenol AP) from the food packaging. 1-Octyl-3-methylimidazoliumhexafluorophosphate ([C8MIM][PF6]) was selected as extraction solution. The extraction procedure did not require a dispersive solvent. Three EDCs extraction kinetics were found to be very fast and the equilibrium was attained within 3.0 min following the pseudo-first-order model. The H-bonding and hydrophobic interactions play an important role in the partitioning of EDCs into IL from aqueous solution. The recovered IL could be reused for three runs without significant loss of extraction efficiencies. The spiked recoveries of three targets in food packaging were in the range of 97.8-103.1%. The limits of detection ranged from 0.50 to 1.50 ng mL(-1) (S/N=3). As a result, this method has been successfully applied for the sensitive detection of three EDCs in real samples.

  20. New approach applying a pet fish air pump in liquid-phase microextraction for the determination of Sudan dyes in food samples by HPLC.

    Science.gov (United States)

    Sricharoen, Phitchan; Limchoowong, Nunticha; Techawongstien, Suchila; Chanthai, Saksit

    2017-07-27

    A new approach applying a pet fish air pump is introduced to develop an extraction method, namely, air-pump-enhanced emulsion, followed by salt-assisted emulsion breaking based on solidified floating organic drop microextraction for the extraction and preconcentration of Sudan I-IV before high-performance liquid chromatography. The applicability of this method was successfully demonstrated by determination of these dyes in four chili products that include chili powder, chili oil, chili sauce, and chili paste. An enrichment factor of 62 was obtained only with a sample solution of 5 mL. A linear range of 0.5-2500 ng/mL was obtained with a limit of detection of 0.16-0.24 ng/mL and recovery of 90-110%. This method is superior to other liquid-liquid extraction methods, as is simple, rapid, environmental friendly, and its phase separation needs no centrifugation. It also needs no disperser solvent and requires less organic solvent, and satisfies the criteria to be called as a green extraction. Therefore, this facile extraction method can be successfully applied in the determination of Sudan dyes in food samples. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. 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.

  2. In situ metathesis reaction combined with liquid-phase microextraction based on the solidification of sedimentary ionic liquids for the determination of pyrethroid insecticides in water samples.

    Science.gov (United States)

    Hu, Lu; Zhang, Panjie; Shan, Wanyu; Wang, Xuan; Li, Songqing; Zhou, Wenfeng; Gao, Haixiang

    2015-11-01

    A novel dispersion liquid-liquid microextraction method based on the solidification of sedimentary ionic liquids (SSIL-DLLME), in which an in situ metathesis reaction forms an ionic liquid (IL) extraction phase, was developed to determine four pyrethroid insecticides (i.e., permethrin, cyhalothrin, fenpropathrin, and transfluthrin) in water followed by separation using high-performance liquid chromatography. In the developed method, in situ DLLME was used to enhance the extraction efficiency and yield. After centrifugation, the extraction solvent, tributyldodecylphosphonium hexafluorophosphate ([P44412][PF6]), was easily collected by solidification in the bottom of the tube. The effects of various experimental parameters, the quantity of tributyldodecylphosphonium bromide ([P44412]Br), the molar ratio of [P44412]Br to potassium hexafluorophosphate (KPF6), the ionic strength, the temperature of the sample solution, and the centrifugation time, were optimized using a Plackett-Burman design to identify the significant factors that affected the extraction efficiency. These significant factors were then optimized using a central composite design. Under the optimized conditions, the recoveries of the four pyrethroid insecticides at four spiked levels ranged from 87.1% to 101.7%, with relative standard deviations (RSDs) ranging from 0.1% to 5.5%. At concentration levels between 1 and 500 µg/L, good linearity was obtained, with coefficients of determination greater than 0.9995. The limits of detection (LODs) for the four pyrethroid insecticides were in the range of 0.71-1.54 µg/L. The developed method was then successfully used for the determination of pyrethroid insecticides in environmental samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. 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.

  4. Picosecond dynamics of reactions in the liquid phase: studies of iodine photodissociation and development of new laser techniques

    Energy Technology Data Exchange (ETDEWEB)

    Berg, M.A.

    1985-09-01

    Iodine photodissociation and recombination was studied as a model for processes common to chemical reaction in the liquid phase. Picosecond transient absorption measurements from 1000 to 295 nm were used to monitor the dynamics in a variety of solvents. Most of the atoms which undergo geminate recombination were found to do so in less than or equal to 15 ps, in agreement with the results of existing molecular dynamics simulations. Vibrational relaxation times vary from approx.15 ps near the middle of the ground state well to approx.150 ps for complete relaxation to v = 0. The prediction of strong resonant vibrational energy transfer to chlorinated methane solvents was not supported, but some evidence for this mechanism was found for alkane solvents. Current theory is unable to explain the large variation (65 to 2700 ps) of the excited A'-state lifetime in various solvents. The 10-Hz amplified, synchronously-pumped dye laser which was used in these studies is described and characterized. SERS (Stimulated Electronic Raman Scattering) and difference frequency mixing were used in the generation of the infrared and far-infrared, respectively. 54 refs., 38 figs., 3 tabs. (WRF)

  5. Dispersive liquid-phase microextraction with solidification of floating organic droplet coupled with high-performance liquid chromatography for the determination of Sudan dyes in foodstuffs and water samples.

    Science.gov (United States)

    Chen, Bo; Huang, Yuming

    2014-06-25

    Dispersive liquid-phase microextraction with solidification of floating organic drop (SFO-DLPME) is one of the most interesting sample preparation techniques developed in recent years. In this paper, a new, rapid, and efficient SFO-DLPME coupled with high-performance liquid chromatography (HPLC) was established for the extraction and sensitive detection of banned Sudan dyes, namely, Sudan I, Sudan II, Sudan III, and Sudan IV, in foodstuff and water samples. Various factors, such as the type and volume of extractants and dispersants, pH and volume of sample solution, extraction time and temperature, ion strength, and humic acid concentration, were investigated and optimized to achieve optimal extraction of Sudan dyes in one single step. After optimization of extraction conditions using 1-dodecanol as an extractant and ethanol as a dispersant, the developed procedure was applied for extraction of the target Sudan dyes from 2 g of food samples and 10 mL of the spiked water samples. Under the optimized conditions, all Sudan dyes could be easily extracted by the proposed SFO-DLPME method. Limits of detection of the four Sudan dyes obtained were 0.10-0.20 ng g(-1) and 0.03 μg L(-1) when 2 g of foodstuff samples and 10 mL of water samples were adopted, respectively. The inter- and intraday reproducibilities were below 4.8% for analysis of Sudan dyes in foodstuffs. The method was satisfactorily used for the detection of Sudan dyes, and the recoveries of the target for the spiked foodstuff and water samples ranged from 92.6 to 106.6% and from 91.1 to 108.6%, respectively. These results indicated that the proposed method is simple, rapid, sensitive, and suitable for the pre-concentration and detection of the target dyes in foodstuff samples.

  6. Determination of low levels of benzodiazepines and their metabolites in urine by hollow-fiber liquid-phase microextraction (LPME) and gas chromatography-mass spectrometry (GC-MS).

    Science.gov (United States)

    de Bairros, André Valle; de Almeida, Rafael Menck; Pantaleão, Lorena; Barcellos, Thiago; e Silva, Sidnei Moura; Yonamine, Mauricio

    2015-01-15

    In this study, it is shown a method for the determination of benzodiazepines and their main metabolites in urine samples by hollow-fiber liquid-phase microextraction (LPME) in the three-phase mode. Initially, the hydrolysis step was performed using 100 μL of sodium acetate 2.0 mol/L buffer solution (pH 4.5), 25 μL of β-glucuronidase enzyme and incubation for 90 min at 55 °C. In parallel with hydrolysis, the LPME fiber (9 cm) was prepared. Its pores were filled with a mixture of dihexyl ether: 1-nonanol (9:1). Afterwards, a solution of 3.0 mol/L of HCl was introduced into the lumen of the fiber (acceptor phase). After hydrolysis, the fiber was submersed in the alkalinized urine (pH 10) containing 10% NaCl. Samples were then submitted to orbital shaking (2400 rpm) for 90 min. The acceptor phase was later withdrawn from the fiber, dried and the residue derivatized with trifluoroacetic anhydride (TFAA) for 10 min at 60 °C with further addition of N-methyl-N-tert-butyldimethylsilyltrifluoroacetamide containing 1% tert-butyldimethylchlorosilane (MTBSTFA) for 45 min at 90 °C followed by determination by gas chromatography-mass spectrometry (GC-MS). The calibration curves obtained showed linearity over the specified range, with a similar sensitivity to traditional techniques and a higher detection capability compared to most of the miniaturized methods described in the literature. The method has been developed and successfully validated and applied to urine samples from real cases of benzodiazepines intake.

  7. Molecular dynamics simulation of liquid phase adsorption of alkaloid on graphite surface

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, M.; Wang, D.; Sakoda, A. [The University of Tokyo, Tokyo (Japan). Institute of Industrial Science

    1997-10-20

    A methodology for molecular dynamics simulation of alkaloid adsorption onto solid surfaces from solutions is developed by employing berberine as a model alkaloid, and water, methanol and N,N-dimethylformamide (DMF) as model solvents. A single berberine molecule and a salvation shell around it are considered as the solution model. The behavior of berberine at the vacuum-solid interface and at the solution-solid interface were simulated, and it is found that a berberine molecule adsorbed with its molecular plane parallel to the graphite surface is most stable, and the molecular conformation does not change considerably during dissolution in the solvents and adsorption onto the graphite. Also, the solvent effects on the adsorption are focused on by analyzing the potential energy change of berberine molecule being adsorbed onto the graphite surface from the solutions by molecular dynamics calculations, and discussed quantitatively by combining solvophobic theory and calculations of the potential energy by molecular simulation. It is known that the presence of water or methanol has little effect on the adsorption of berberine onto the graphite surface, and that the presence of DMF inhibits the adsorption of berberine significantly. It can be said that the methodology developed in this work is useful for studying the solvent effects on adsorption, and for choosing proper solvents in adsorptive separation and purification processes for alkaloids. 31 refs., 9 figs., 4 tabs.

  8. Cooperative motion in liquids: On librational dynamics of chloroform throughout its normal liquid-phase range

    Science.gov (United States)

    Rothschild, Walter G.; Cavagnat, Raymond M.

    1994-03-01

    We have extended the Raman spectral accumulations of the ν3 mode (A1, 367 cm-1) of liquid CHCl3-Cl-35 and its simulation in terms of an orientational equilibrium renewal process [W. G. Rothschild, R. M. Cavagnat, and P. Maraval, J. Chem. Phys. 99, 8922 (1993)] to a temperature of 338 K, about the normal boiling point of the system (335 K). The values of the best-fit parameters predict that the orientational motion of liquid chloroform, even at such a relatively high kinetic energy, is described predominantly by libratory states; their lifetime (˜1 ps) is four times longer than that of the free-rotational steps. The character of the orientational motion of the system, when traversing the range of 213 to 338 K from just above its melting to near its boiling point at about atmospheric pressure, reflects the softening of the liquid-cage structure in terms of an increasing dispersion and/or a decreasing value of the mean libration frequency, a lowering of the depth of its potential well, but near-invariance of its lifetime. Simultaneously, there is an approximately twofold increase in the lifetime of the much shorter stages of free-rotational motion. In essence, the system dynamics remain that of an assembly of librators.

  9. Molecular dynamics studies on liquid-phase dynamics and structures of four different fluoropropenes and their binary mixtures with R-32 and CO2.

    Science.gov (United States)

    Raabe, Gabriele

    2014-01-01

    Fluoropropenes such as R-1234yf or R-1234ze(E) have attracted attention as low GWP (global warming potential) refrigerants, both as pure compounds but also to an increasing extent as components in refrigerant blends. In our earlier work [Raabe, G.; Maginn, E. J. J. Phys. Chem. B 2010, 114, 10133-10142 and Raabe, G. J. Phys. Chem. B 2012, 116, 5744-5751], we have introduced a transferable force field for different fluoropropene compounds. This molecular model has already been applied for predictive molecular simulation studies on the vapor-liquid phase equilibria in binary mixtures of the tetrafluoropropenes R-1234yf or R-1234ze(E) with the difluoromethane R-32 and CO2. In this work we present molecular dynamics simulations on the liquid phase properties of the pure fluoropropenes R-1234yf, R-1234ze, R-1234ze(E), and R-1216 and their binary mixtures with CO2 and R-32. Our study covers temperatures from 273 to 313 K, pressures up to 3.5 MPa, and different mixture compositions. We provide predictions on the densities and transport properties of the pure compounds and the binary mixtures to complement experimental data. Additionally, we have analyzed radial and spatial distribution functions in the systems to gain insight into their microscopic structures and preferred interaction sites.

  10. Determination of trace diethylstilbestrol in urine by hollow fiber membrane/liquid-phase microextraction combined with HPLC%中空纤维膜液相微萃取-高效液相色谱联用技术测定尿液中痕量己烯雌酚

    Institute of Scientific and Technical Information of China (English)

    张玉; 刘雷英

    2012-01-01

    采用中空纤维液相微萃取与高效液相色谱联用技术测定了尿液样品中的痕量己烯雌酚;考察了样品相酸度、中间相种类、接收相浓度、搅拌速度、萃取时间等对液-液-液三相微萃取效率的影响,进而确定了最佳萃取条件.结果表明,当样品相pH为2.5,中间相为甲苯,接收相为3μL 0.25 mol/L氢氧化钠溶液,搅拌速度为800r/min,萃取时间为50 min时,萃取效率最佳.在最佳萃取条件下,样品的回收率为76.4%,相对标准偏差为3.8%.%Trace diethylstilbestrol in urine samples was determined by combining hollow fiber membrane/liquid-phase microextraction with high performance liquid chromatography. The effects of donor phase pH, intermediate type, acceptor phase concentration, stirring rate, and extraction time on liquid-liquid-liquid tri-phase microextraction efficiency were investigated, and the optimal microextraction condition was established accordingly. Results indicate that, when toluene is used as the intermediate phase and 3 μL of 0. 25 mol/L NaOH solution as the acceptor phase, the best microextraction efficiency is obtained after 50 min of extraction under a stirring rate of 800 r/min. The recovery of the tested urine samples is 76. 4% and the relative standard deviation is 3. 8% under the optimized microextraction condition.

  11. HF-LLLME-CE法测定偶氮染料氧化降解生成的有机酸%Determination of Organic Acids Generated from Degraded Azo Dyes by Three Phase Liquid Phase Microextraction with Capillary Chromatography

    Institute of Scientific and Technical Information of China (English)

    李海燕; 龚丹; 刘红玉

    2012-01-01

    采用纤维膜三相液相微萃取(HF-LLLME)和毛细管电泳技术,对偶氮染料氧化降解过程中可能产生的小分子羧酸甲酸、乙酸、草酸、乳酸、丁二酸、柠檬酸、苹果酸进行了测定.以pH值为7.2的230 mmol/L磷酸二氢钠、115 mmol/L四硼酸钠和0.5 mmol/L十六烷基三甲基溴化铵(CTAB)溶液为缓冲液,分离电压-12 kV,检测波长200nm的条件下,10 min内达到基线分离.三相液相微萃取以磷酸三丁酯(TBP)为有机相,供体相pH为25,接收相pH为12.0,萃取时间为45min,将萃取接收相直接进行毛细管电泳(CE)测定,富集倍数在7~67之间.样品相中7种有机酸的质量浓度在5mg/L~1000 mg/L的范围内与电泳峰面积呈良好线性(r2>0.9991),方法的检出限为0.09mg/L~0.54 mg/L.运用该法对TiO2光催化降解偶氮染料过程中产生的有机酸进行测定,检测到的4种羧酸的投加回收率在93%~110%之间.%A noval method of capillary electrophoresis(CE) coupled with hollow fiber three phase liquid phase microextraction (HF-LLLME) was developed for determination of 7 low molecular mass organic acids including formic acid, acetic acid, oxalate, succinic acid, citric acid, malic acid, tartaric acid and lactic acid which may be the degradation products of Reactive Brilliant Red X-3B. Baseline separation of 7 organic acids was achieved within 10 min by using 230 mmol/L NaH2PO4,115 mmol/L Na2B4O7 and 0.5 mmol/L CTAB at pH 7.2 with a constant temperature of 25 ℃, detection wavelength 200 run and separation voltage -12 kV. Under the optimized LPME condition, tri-butyl-phosphate (TBP) as organic phase, donor phase pH 2.5, acceptor phase pH 12.0, without addition of salt, an enrichment factors ranged from 7 to 67 could be achieved within 45 min extraction. The receiving phase could be used for capillary electrophoresis analysis without any further treatment Calibration curves for 7 organic acids were well correlated within the range of 5 mg/L-1 000

  12. Dynamic speciation analysis of atrazine in aqueous latex nanoparticle dispersions using solid phase microextraction (SPME)

    NARCIS (Netherlands)

    Benhabib, K.; Town, R.M.; Leeuwen, van H.P.

    2009-01-01

    Solid phase microextraction (SPME) is applied in the dynamic speciation analysis of the pesticide atrazine in an aqueous medium containing sorbing latex nanoparticles. It is found that the overall rate of extraction of the analyte is faster than in the absence of nanoparticles and governed by the

  13. Understanding the stabilization of liquid-phase-exfoliated graphene in polar solvents: molecular dynamics simulations and kinetic theory of colloid aggregation.

    Science.gov (United States)

    Shih, Chih-Jen; Lin, Shangchao; Strano, Michael S; Blankschtein, Daniel

    2010-10-20

    Understanding the solution-phase dispersion of pristine, unfunctionalized graphene is important for the production of conducting inks and top-down approaches to electronics. This process can also be used as a higher-quality alternative to chemical vapor deposition. We have developed a theoretical framework that utilizes molecular dynamics simulations and the kinetic theory of colloid aggregation to elucidate the mechanism of stabilization of liquid-phase-exfoliated graphene sheets in N-methylpyrrolidone (NMP), N,N'-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), γ-butyrolactone (GBL), and water. By calculating the potential of mean force between two solvated graphene sheets using molecular dynamics (MD) simulations, we have found that the dominant barrier hindering the aggregation of graphene is the last layer of confined solvent molecules between the graphene sheets, which results from the strong affinity of the solvent molecules for graphene. The origin of the energy barrier responsible for repelling the sheets is the steric repulsions between solvent molecules and graphene before the desorption of the confined single layer of solvent. We have formulated a kinetic theory of colloid aggregation to model the aggregation of graphene sheets in the liquid phase in order to predict the stability using the potential of mean force. With only one adjustable parameter, the average collision area, which can be estimated from experimental data, our theory can describe the experimentally observed degradation of the single-layer graphene fraction in NMP. We have used these results to rank the potential solvents according to their ability to disperse pristine, unfunctionalized graphene as follows: NMP ≈ DMSO > DMF > GBL > H(2)O. This is consistent with the widespread use of the first three solvents for this purpose.

  14. Liquid phase microextraction of Di-(2-ethylhexyl) phthalate from polymer films with deep eutectic solvent by open circuit potentiometric and PM7 semiempirical molecular orbital method%塑料膜中塑化剂(DEHP)低共熔溶剂液相微萃取的开路电位和PM7半经验分子轨道法研究

    Institute of Scientific and Technical Information of China (English)

    陈庆阳; 高杰; 朱永春

    2016-01-01

    Liquid phase microextraction of di-(2-ethylhexyl)phthalate(DEHP)with deep eutectic solvent(DES)of choline chloride-urea was studied by opencircuit potentiometry,which shows a first order dynamic property with apparent first order dynamic constant of 6. 35×10-4 s-1,and can be used in the detection the amount of DEHP from different plastic films. Thermodynamic parameters of molecular clusters composed of DES and DEHP were calculated by PM7 semiempirical molecular orbital method. The results show that the interactions between DES and DEHP is a spontaneous process with three DES molecules supporting one DEHP molecule, which offers an theoretical evidence for the microextraction of DEHP with DES.%开路电位法研究了邻苯二甲酸二(2-乙基)己基酯在尿素-氯化胆碱碳糊电极表面上微萃取行为。在6000s的饱和萃取时间下的开路电位差与邻苯二甲酸二(2-乙基)己基酯在萃取溶液中的浓度呈反比,其表观一级动力学常数为6.35×10-4 s-1,可应用于不同塑料膜中邻苯二甲酸二(2-乙基)己基酯的相对含量的检测。基于DES与DEHP相互作用的分子簇模型,半经验分子轨道量子化学方法计算了分子簇的热力学参数,表明DES与DEHP相互作用形成分子簇过程为自发过程,三个DES可以支撑一个DEHP分子,为DES萃取有机酯类化合物提供理论依据。

  15. 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.

  16. 三相中空纤维膜液相微萃取-高效液相色谱法测定水中痕量双酚A%Determination of Trace Bisphenol-A in Water Using Three-phase Hollow Fiber Liquid Phase Microextraction Coupled with High Performance Liquid Chromatography

    Institute of Scientific and Technical Information of China (English)

    谭小旺; 宋燕西; 魏瑞萍; 易谷洋

    2012-01-01

    A method for the determination of trace bisphenol-A (BPA) in water was developed by HPLC using three-phase hollow fiber liquid phase microextraction as sample preparation technique. The system of three-phase hollow fiber liquid phase microextraction was designed. The optimized microextraction conditions were as follows: 1-octanol was used as the extraction solvent, the concentration of NaOH solution as acceptor phase was 0. 09 mol/L, the pH value of sample solutions was 4. 0, the NaCl concentration in sample solutions was 30 g/L, the stirring rate was 900 r/min and the extraction time was 60 min. The determination of BPA was finished with injecting 20 μL acceptor phase by HPLC. Under the optimal microextraction conditions, the linear range for BPA was 0. 5 - 200 μg/L (r>0. 999), the detection limits (S/N = 3) of BPA was 0. 2 μg/L, the enrichment factor was 241. 1, and the relative standard deviations (RSD) was lower than 3. 2%. The proposed method was applied to the determination of the BPA in environmental water samples. The spiked average recoveries were within the range of 92.8% -101.9% (w = 3). The developed method is simple and environmentally friendly for the determination of BPA in water.%建立了三相中空纤维膜液相微萃取-高效液相色谱(HF-LPME-HPLC)方法,用于分析测定水中痕量双酚A的含量.设计了三相中空纤维膜液相微萃取系统,优化的HP-LPME最佳萃取条件为:萃取剂为正辛醇,接受相NaOH浓度为0.09 mol/L,样品溶液pH=4.0,NaC1加入量为30 g/L,搅拌速度为900 r/min,萃取时间为60 min.萃取后取20 μL接受相进行色谱分析.在最佳萃取条件下,方法的线性范围为0.5~200 μg/L(r> 0.999),检出限(信噪比为3)为0.2 μg/L;富集因子为241;方法RSD<3.2% (n=3).在实际环境水样中添加5,20和50μg/L的双酚A标准物质,加标平均回收率为92.8%~101.9%.表明本方法可用于水中痕量双酚A的快速准确测定.

  17. Computational Fluid-dynamics of Liquid Phase Flow on Distillation Column Trays%利用计算流体力学方法研究精馏塔板上的液相流动

    Institute of Scientific and Technical Information of China (English)

    刘春江; 袁希钢

    2002-01-01

    A computational fluid-dynamics model is presented for predicting the two-phase two-dimensional liquid phase flow on a distillation column tray based on the modification of Navier-Stokes Equation by considering both the resistance and the enhanced turbulence created by the uprising vapor. Experimental measurement of the local liquid phase velocity on an air-water simulator of 1.2 m in diameter by using the hot film anemometer is briefly described. Two of the conventional fluid-dynaxmic constants are readjusted for the case of liquid flow on a tray by fitting the experimental data. The predicted local liquid phase velocity and direction of flow by the present model are confirmed satisfactorily by the authors' experimental measurements and by the data from literature. By the aid of the present model, the concentration field on the tray can be computed for the evaluation of the enhancement of liquid phase concentration across a tray. The advantages of applying computational fluid-dynamics to tray column design are discussed.

  18. Determination of Strychnine and Brucine in Cleaning Residue by Hollow Fiber-Liquid Phase Microextraction and HPLC%士的宁及马钱子碱清洁残留物的中空纤维液相微萃取-高效液相色谱法测定

    Institute of Scientific and Technical Information of China (English)

    许萌; 康丽娟; 蒋晔

    2013-01-01

    A hollow fiber-liquid phase microextraction (HF-LPME)-HPLC method was established for the determination of trace strychnine and brucine in cleaning validation of productional equipment.Parameters influencing the extraction efficiency were investigated and optimized.The enrichment factors of strychnine and brucine were 80.6 and 122.4,respectively,under extraction by n-octyl alcohol and agitating at 800 r/min for 60 min.An HPLC method was applied for the determination.A C18 column was used with the mobile phase of 0.4% phosphoric acid (adjusted to pH 3.0 by triethylamine)-acetonitrile (85 ∶ 15) at the detection wavelength of 260 nm.The calibration curves for strychnine and brucine were linear in the range of 0.01-1 μg/ml.Their recoveries were 98.3% and 98.5%,with RSDs of 0.4% and 0.6%.

  19. Determination of widely used non-steroidal anti-inflammatory drugs in water samples by in situ derivatization, continuous hollow fiber liquid-phase microextraction and gas chromatography-flame ionization detector.

    Science.gov (United States)

    Es'haghi, Z

    2009-05-08

    The aim of this study was to develop an analytical procedure which allows the quantification of pharmaceuticals in water at the ng L(-1) level. Hence, it is reported research on the application of a rapid, inexpensive and simple continuous hollow fiber liquid-phase micro extraction (CHF-LPME) for the pre-concentration and determination of non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen (IBP), naproxen (NAP), and ketoprofen (KEP), in wastewater. In this method, a 2.50 cm end sealed piece of a polypropylene hollow fiber was immersed into the organic solvent, octanol, for 30 s. After solvent impregnation with the pores of the fiber, the excess amounts of solvent were removed from inside the fiber, and 4.0 microL of octanol, as the acceptor phase, was injected into the fiber carefully. The fiber was settled using a microsyringe into a 10.0 mL glass test tube, and 20.00 mL of the aqueous solution (the donor phase), was circulated by a pump around it. After analyte extraction for an optimized period of time (20 min), 2 microL of the organic solvent was withdrawn into the microsyringe and injected into the GC-FID for further analysis. Finally, based on the optimized analytical conditions, the method was linear in the range of 2.5-500 ng L(-1). The limits of detection were 1-2 ng L(-1). Repeatability of this method on an intra-day scale was 3.4-10.2% (RSD%). NSAIDs have been detected in several municipal wastewater samples, and the concentration range was 9.0-19.0 ng L(-1).

  20. Ionic liquid-assisted liquid-phase microextraction based on the solidification of floating organic droplets combined with high performance liquid chromatography for the determination of benzoylurea insecticide in fruit juice.

    Science.gov (United States)

    Yang, Miyi; Zhang, Panjie; Hu, Lu; Lu, Runhua; Zhou, Wenfeng; Zhang, Sanbing; Gao, Haixiang

    2014-09-19

    A green, simple, and efficient method, ionic liquid-assisted liquid-liquid microextraction based on the solidification of floating organic droplets (ILSFOD-LLME) collected via a bell-shaped collection device (BSCD) coupled to high performance liquid chromatography with a variable-wavelength detector, was developed for the preconcentration and analysis of seven benzoylurea insecticides (BUs) in fruit juice. In the proposed method, the low-density solvent 1-dodecanol and the ionic liquid trihexyl(tetradecyl)phosphonium hexafluorophosphate ([P14, 6, 6, 6]PF6) were used as extractant. The extraction solvent droplet was easily collected and separated by the BSCD without centrifugation. The experimental parameters were optimized by the one-factor-at-a-time approach and were followed using an orthogonal array design. The results indicated the different effects of each parameter for extraction efficiency. Under the optimal conditions in the water model, the limits of detection for the analytes varied from 0.03 to 0.28μgL(-1). The enrichment factors ranged from 160 to 246. Linearities were achieved for hexaflumuron and flufenoxuron in the range of 0.5-500μgL(-1), for triflumuron, lufenuron and diafenthiuron in the range of 1-500μgL(-1), and for diflubenzuron and chlorfluazuron in the range of 5-500μgL(-1); the correlation coefficients for the BUs ranged from 0.9960 to 0.9990 with recoveries of 75.6-113.9%. Finally, the developed technique was successfully applied to real fruit juice with acceptable results. The relative standard deviations (RSDs) of the seven BUs at two spiked levels (50 and 200μgL(-1)) varied between 0.1% and 7.3%.

  1. Determination of BPA in Milk by Liquid-Phase Microextraction and Chromatography-Mass Spectrometry%液相微萃取-GC-MS法测定奶粉中双酚A

    Institute of Scientific and Technical Information of China (English)

    顾海东; 邵焰; 张丽君; 张占恩

    2013-01-01

    采用液相微萃取-气相色谱质谱法测定奶粉中的双酚A.通过实验优化了样品制备和萃取条件,最佳萃取条件:奶粉与水的比例为1:4,pH值为6.5,超声3 min,苯为萃取剂,萃取温度35℃,搅拌速率650 r/min,萃取时间15min,萃取后取1μL萃取剂进行色谱分析.在此条件下,当采用选择离子扫描模式时,奶粉中双酚A的线性范围为0.01 ~25 mg/kg,线性相关系数,=0.9992,方法检出限为0.0002 mg/kg.测定结果的相对标准偏差为4.9%(n=6),加标回收率为100.9%~103.4%.该方法可用于奶粉中双酚A的快速测定.%BPA in milk was determined by liguid-phase microextraction (LPME) coupled to gas chromatography-mass spectrometry (GC-MS). The sample preparation and extraction conditions ware optimized, and the optimum conditions obtained as the following: ratio of milk to water was 1 : 4, pH value was 6.5, ultrasonic time was 3 min, extraction solvent was benzene, extraction temperature was 35℃, stirring speed was 650 r/min and extraction time was 15 min. After extraction, 1 μL organic solvent was introduced to GC-MS for analysis. Under the optimized conditions, selected-ion mode (SIM) was used, the linear range of BPA was 0.01-25 mg/kg, r2 = 0.9992, and the detection limit(LOD) was 0.0002 mg/kg. The relative standard deviations of detection results was 4.9%(n=6), the recovery was 100.9%-103.4% . The method is suitable for the determination of BPA in milk.

  2. 液相微萃取-高效液相色谱法分析葡萄汁中多酚类化合物%Determination of polyphenols in grape juice by liquid-phase microextraction coupled with high performance liquid chromatography

    Institute of Scientific and Technical Information of China (English)

    胡玉玲; 常蓓蓓; 罗学军; 李攻科

    2009-01-01

    A novel method for the determination of ellagic acid, resveratrol and quercetin in grape juice by liquid-phase microextraction (LPME) coupled with high performance liquid chromatography (HPLC) was developed. The results of two different modes of LPME were compared, and the single drop microextraction exhibited better extraction efficiency. Effects of stirring speed, extraction time, ionic strength, and pH were investigated. The enrichment factors of ellagic acid, resveratrol and quercetin were 48.4, 79.4 and 155.8, respectively. The linear range of the method was from 0.0050 to 5.0 μg/mL. The detection limits of ellagic acid, resveratrol and quercetin were 0.015, 0.0020, 0.0080 μg/mL, and the RSDs were 2.0%, 1.8% and 1.7%, respectively. The recoveries were from 81.9% to 102.3% for grape juice samples. The method with little solvent consumption was simple, fast, sensitive and suitable for the determination of polyphenols in plant samples.%建立了一种基于液相微萃取与高效液相色谱联用技术测定葡萄汁中鞣花酸、白藜芦醇和槲皮素的分析方法. 比较了单液滴液相微萃取和中空纤维液相微萃取两种萃取模式, 选择了单液滴液相微萃取作为3种多酚类化合物的液相微萃取模式. 考察了搅拌速度、萃取时间、料液相pH和料液相离子强度的影响. 鞣花酸、白藜芦醇和槲皮素的富集倍数分别为48.4、 79.4和155.8, 方法的线性范围为0.0050~5.0 μg/mL, 鞣花酸、白藜芦醇和槲皮素的检出限分别为0.015, 0.0020, 0.0080 μg/mL, 相对标准偏差分别为2.0%, 1.8%和1.7%. 用于实际样品葡萄汁的分析, 加标回收率在81.9%~102.3%之间.

  3. Determination of Trace Amounts of Lead with ETAAS After Single Drop Microextraction and Dispersive Liquid Liquid Microextraction Methods

    OpenAIRE

    Efeçınar M.; Çakır P.; Şatıroğlu N.

    2013-01-01

    Two liquid-phase microextraction procedures, single-drop microextraction (SDME) and dispersive liquid–liquid microextraction (DLLME), have been developed for the determination of lead by electrothermal atomic absorption spectrometry (ETAAS). Both methods were based on the formation of lead iodide-Rhodamine B complex which is in phosphoric acid medium. In the presence of KI, anionic lead iodide was complexed with Rhodamine B as an ion-association complex. Several factors that may be affected o...

  4. [Determination of amphetamines in human hair using dynamic liquid-phase microextraction and gas chromatography/selected ion monitoring-mass spectrometry after microwave derivatization].

    Science.gov (United States)

    Zhu, Dan; Meng, Pinjia; He, Hongyuan

    2007-01-01

    Human hair is an important specimen for drug abuse analysis owing to its easy collection, long surveillance time window and good correlation between the "degree of addiction" and actual drug concentration. A simple method for determination of 4 amphetamines in human hair was developed. The hair was digested under basic condition, and the drugs in it were extracted using microvolume of chloroform. The organic layer was then transferred into another tube to be derivatized with N-methyl-bis (trifluoroacetamide) (MBTFA) by microwave heating. Finally the reacted solution was detected by gas chromatography/selected ion monitoring-mass spectrometry (GC/SIM-MS) directly. 2-Methyl-phenyl ethylamine was used as an internal standard. Good linearities were obtained for 4 amphetamines with correlation coefficients better than 0.996. The limits of detection, based on a signal-to-noise ratio (S/N) of 3:1, were all about 50 pg/mg for amphetamine (AM) , methamphetamine (MAM), methylenedioxy-amphetamine (MDA), and methylenedioxy-methamphetamine (MDMA) in hair. The reproducibility of the method was satisfactory, with the relative standard deviations of 6.0% for AM, 13.9% for MAM, 10.2% for MDA and 9.2% for MDMA. Some real hair from the drug abusers was analyzed with this method. The minimal hair is less than 5 mg (about 20 cm). The method is highly sensitive, easy to operate, time-saving and economic, which can be used for trace analysis of amphetamines in human hair.

  5. 用中空纤维液相微萃取-HPLC法测定人血浆中酒石酸美托洛尔的浓度%Determination of the concentration of metoprolol tartrate in human plasma by HPLC coupled with hollow fiber liquid phase microextraction method

    Institute of Scientific and Technical Information of China (English)

    宫雪菲; 马海英; 易丽昕; 刘亚非

    2012-01-01

    Objective: To establish a HPLC coupled with hollow fiber liquid phase microextraction(HF-LPME) method for determination of the concentration of metoprolol tartrate in human plasma. Methods: The concentrations of donor phase and receptive phase,time, temperature and rotary speed of extraction,and concentration of NaCl in HF-LPME were optimized. The hollow fiber was placed in plasma sample solution to perform microextraction, and then the extract was analyzed by HPLC method with fluorescence detection on Agilent Zorbax XDB-C13 column. The mobile phase consisted of methanol-0. 1% phosphoric acid(40 ! 60) with a flow rate of 1 ml/min. The excitation wavelength was 227 nm and the emission wavelength was 305 nm. The column temperature was 30 C. Results: Metoprolol tartrate was in good linearity within the range of 2-125 ng/ml. The intra-day and inter-day RSD of low, middle and high concentrations ( 5, 20, 100 ng/ml) were all less than 10%, and recoveries were (87. 1±7. 3) % , (92. 6±5. 8) % and (89. 1±2. 5) % .respectively. Conclusion: HPLC coupled with HF-LPME method is suitable for analysis of concentration of metoprolol tartrate in human plasma.%目的:建立中空纤维液相微萃取-HPLC法测定人血浆中酒石酸美托洛尔的浓度.方法:优化酒石酸美托洛尔液相微萃取法供给相和接受相的浓度、萃取时间、萃取温度、萃取转速和离子强度,血浆样品经中空纤维液相微萃取法萃取后,用HPLC法测定酒石酸美托洛尔的浓度.色谱柱:Agilent Zorbax Eclipse XDB-C18柱,流动相:甲醇-0.1%磷酸(40∶60),流速:1 ml/min,激发波长:227 nm,发射波长:305 nm,柱温:30℃.结果:酒石酸美托洛尔在2~ 125 ng/ml线性关系良好,低、中、高三种浓度(5、20、100 ng/ml)的日内、日间精密度均<10%,回收率分别为(87.1±7.3)%、(92.6±5.8)%和(89.1±2.5)%.结论:中空纤维液相微萃取-HPLC法适用于测定血浆样品中酒石酸美托洛尔的浓度.

  6. Determination of amphetamines in urine by hollow fiber-based liquid-phase microextraction and chromatography-mass spectrometry%中空纤维膜液相微萃取-气相色谱/质谱法检测尿液中的苯丙胺类兴奋剂

    Institute of Scientific and Technical Information of China (English)

    张文文; 孟品佳; 孟梁; 王丹

    2013-01-01

    建立了尿液中痕量苯丙胺类毒品的中空纤维膜液相微萃取-气相色谱/质谱检测方法.采用中空纤维膜液相微萃取技术萃取尿液中4种苯丙胺类毒品,研究萃取剂类型、体积、溶液pH、萃取时间和温度等对萃取效果的影响.尿液中4种苯丙胺类毒品的最佳萃取条件为:样品溶液pH 13,甲苯为萃取剂,搅拌速度500 r/min,30 ℃条件下萃取15 min;此条件下苯丙胺(AM)、甲基苯丙胺(MAM)、3,4-亚甲二氧基苯丙胺(MDA)、3,4-亚甲二氧基甲基苯丙胺(MDMA)的检出限(S/N=3)分别为1.0,0.75,1.0,0.64 ng/mL,相对标准偏差分别为6.62%,3.98%,4.57%,2.35%,富集倍数分别为155,170,132,218倍.本方法可用于尿液中痕量苯丙胺类毒品的分析测定.%Objective A novel method was developed to determine the trace amounts of amphetamine-type stimulants in urine by GC-MS coupled with hollow fiber membrane solvent microextraction. Methods Hollow fiber membrane liquid phase microextraction technology was adopted to extract amphetamines in urine after optimization of extraction conditions, such as solvent, volume, pH, stirring speed, time and temperature. Results Optimization of the extraction for amphetamines in urine was; toluene being used as extraction solvent, the target analytes in urine were extracted under pH 13 with temperature at 30 ℃ , stirring speed at 500 r/min, for 15 min. Under the optimized conditions, the LODs of amphetamine, methamphetamine, MDA, MDMA were 1. 0, 0. 75 , 1. 0 and 0. 64 ng/mL; the RSDs were 6. 62% , 3. 98% , 4. 57% , 2. 35% ; and the enrichment factors were 155, 170, 132, 218, respectively. Conclusion The results demonstrated that the method was feasible for the determination of the trace amounts of amphetamine-type stimulants in urine.

  7. Determination of Dichloromethane and Acetone Residues in Azithromycin by Headspace Liquid Phase Microextraction Coupled with Gas Chromatography%顶空液相微萃取-气相色谱法测定阿奇霉素中二氯甲烷和丙酮残留量

    Institute of Scientific and Technical Information of China (English)

    云丹; 王凯莹

    2015-01-01

    采用液相微萃取与气相色谱联用技术测定阿奇霉素中二氯甲烷和丙酮的残留量. 以苯乙酮为萃取溶剂,萃取时间30 min,萃取温度60℃,萃取液滴体积2μL. 在浓度为20. 0μg/g ~120. 0μg/g范围内,二氯甲烷的外标曲线为Y=0. 009 9X -0. 088 2,相关系数R2 =0. 983 1;丙酮的外标曲线为Y=0. 029 1X-0. 040 5,相关系数R2 =0. 986 5;阿奇霉素中丙酮测定结果的相对标准偏差(RSD%)为1. 19,加标回收率为93. 49% ~101. 1%;方法的最低检测限:二氯甲烷为0. 298 μg/g,丙酮为0. 059 μg/g.%A method was used for the determination of residual dichloromethane and trichloromethane in raniti-dine hydrochloride by liquid phase microextraction coupled with gas chromatography( GC) . Acetophenone was as ex-traction solvent, the extraction time was 30 min, the extraction temperature was 60 ℃,the extraction liquid drop vol-ume was 2 μL. The external standard curve of dichloromethane was Y=0. 009 9X-0. 088 2, the correlation coeffi-cient was R2 =0. 983 1 and the external standard curve of acetone was Y=0. 029 1X-0. 040 5,the correlation coeffi-cient was R2 = 0. 9865 within the concentration ranges of dichloromethane(20. 0 μg/g ~120. 0 μg/g). The relative standard deviation ( RSD%) of the determination of acetone in azithromycin was 1 . 19 . The recovery rate was in the range of 93 . 49% ~101 . 1%. The lowest detection limit of method were as follows: the dichloromethane was 0 . 298μg/g,the acetone was 0. 059 μg/g.

  8. 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...

  9. Determination of triazine herbicides in fresh vegetables by dynamic microwave-assisted extraction coupled with homogeneous ionic liquid microextraction high performance liquid chromatography.

    Science.gov (United States)

    Wu, Lijie; Hu, Mingzhu; Li, Zhanchao; Song, Ying; Yu, Cui; Zhang, Yupu; Zhang, Hanqi; Yu, Aimin; Ma, Qiang; Wang, Ziming

    2015-02-01

    A novel extraction method, dynamic microwave-assisted extraction coupled with homogeneous ionic liquid microextraction, was developed for the determination of triazine herbicides, including desmetryn, terbumeton, propazine, terbuthylazine, dimethametryn, and dipropetryn in fresh vegetable samples by high performance liquid chromatography (HPLC). In the developed method, 120 μL of 1-butyl-3-methylimidazolium tetrafluoroborate ([C4MIM][BF4]) was added to 10 mL of aqueous solution containing 0.3 g of NaCl to obtained the extraction solvent. Six triazines could be extracted completely within 4 min by the present method. Then, [NH4][PF6] was added into the extract to form a water-insoluble ionic liquid [C4MIM][PF6] via a simple metathesis reaction, and the analytes were enriched into the ionic liquid phase. After centrifugation and dilution with acetonitrile, the resulting solution was analyzed directly by HPLC. The effects of some experimental parameters, including type and volume of ionic liquid, volume of extraction solvent, amount of ion-pairing agent [NH4][PF6], salt concentration, microwave power, and flow rate of extraction solvent on the extraction efficiency were investigated and optimized. Under the optimum experimental conditions, the linearity for determining the analytes was in the range of 2.50-250.00 μg kg(-1), with the correlation coefficients ranging from 0.9989 to 0.9999. When the present method was applied to the analysis of vegetable samples, satisfactory recoveries were obtained in the range of 76.8%-106.9%, and relative standard deviations were lower than 9.8%.

  10. Dynamic microwave-assisted extraction combined with continuous-flow microextraction for determination of pesticides in vegetables.

    Science.gov (United States)

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

    2016-02-01

    A simple, rapid, solventless and cost-effective dynamic microwave-assisted extraction (DMAE) combined with continuous-flow microextraction (CFME) system was firstly assembled and validated for extraction of eight organophosphorus pesticides in vegetables. The method combines the advantages of DMAE and CFME, and extends the application of the single drop microextraction to complex solid samples. The extraction, separation, and enrichment were performed in a single step, which could greatly simplify the operation and reduce the whole pretreatment time. In the developed method, analytes were first extracted from the vegetables using 3% NaCl solution as extraction solvent, then concentrated into microextraction solvent. After extraction, the microextraction solvent containing the enriched analyte was directly analyzed by GC-MS without any filtration or clean-up process. Several parameters affecting the extraction efficiency were investigated and optimized. Real vegetable samples were analyzed, satisfactory recoveries were obtained in the range of 80.7-106.7%, and relative standard deviations were lower than 8.7%.

  11. Determination of dichloromethane and trichloromethane residues in ranitidine hydrochloride by headspace liquid phase microextraction coupled with gas chromatography%顶空液相微萃取-气相色谱法测定盐酸雷尼替丁中二氯甲烷和三氯甲烷的残留量

    Institute of Scientific and Technical Information of China (English)

    申书昌; 云丹; 李飞

    2009-01-01

    A method for the determination of residual dichloromethane and trichloromethane in ranitidine hydrochloride by headspace liquid phase microextraction coupled with gas chroma-tography (GC) was developed. A homemade device was used to protect the organic drop. The effects of the nature of extraction solvent, extraction time, extraction temperature and micro-drop volume on the extraction efficiency were investigated separately. The optimal experimen-tal conditions were as follows:2 ΜL of n-tridecane as extraction solvent, 30 min of extraction time, 60 ℃ of extraction temperature. The correlation coefficients of linear calibration curve were 0. 973 3 and 0. 972 4 within the concentration ranges of dichloromethane (1-10 μg/g) and trichloromethane (1-10 μg/g), respectively. The detection limits of dichlormethane and tri-chloromethane were 0. 027 3 μg/g and 0. 041 0 μg/g, respectively, the relative standard devia-tions were lower than 4. 36% and 5. 89%, and the recoveries of the method were 93. 6% - 102% and 98.1% -103%, respectively. The method is simple and reliable.%采用顶空液相微萃取与气相色谱联用技术测定雷尼替丁中二氯甲烷和三氯甲烷的残留量.自制了萃取液保护装置.考察了萃取溶剂的种类、萃取时间、萃取温度、萃取液的体积对二氯甲烷和三氯甲烷萃取效果的影响.以正十三烷为萃取剂,在60 ℃下萃取30 min,萃取液滴体积2 μL.二氯甲烷含量在1~10 μg/g范围内与色谱峰高呈线性关系,相关系数(r~2)为 0.973 3;三氯甲烷含量在1~10 μg/g范围内与色谱峰高呈线性关系,r~2为 0.972 4.二氯甲烷和三氯甲烷的最低检出限分别为 0.027 3 μg/g和 0.041 0 μg/g,加标回收率分别为93.6% ~102%和98.1% ~103% .方法简便易行,测定结果准确.

  12. Determination of Trace Ephedrine and Pseudoephedrine in Urine Sample by Hollow Fiber- Liquid Phase Microextraction and HPLC%中空纤维液-液-液微萃取/HPLC分析人尿液中麻黄碱及伪麻黄碱

    Institute of Scientific and Technical Information of China (English)

    刘彦; 张福成; 蒋晔

    2012-01-01

    建立了中空纤维液-液-液微萃取高效液相色谱对人尿液中的麻黄碱和伪麻黄碱进行纯化、分离、富集以及测定的方法.采用中空纤维三相微萃取装置,考察了影响萃取的因素,确定了萃取条件:中空纤维壁上的有机相为正辛醇,以50μL盐酸溶液(pH 2.0)为接受相,在室温下萃取60 min.该条件下麻黄碱和伪麻黄碱的富集倍数分别为180倍和220倍,两者的线性范围分别为0.01~5 mg/L和0.005~0.75 mg/L,相关系数(r)分别为0.998 2、0.997 8,定量下限分别为0.01、0.005 mg/L.该方法使用极少量的有机溶剂,便可有效地对尿样中麻黄碱和伪麻黄碱进行纯化、分离和富集,萃取效率高,可用于尿液中麻黄碱和伪麻黄碱的同时测定.%A simple and sensitive method based on hollow fiber liquid phase microextraction ( HF -LPME) was developed to separate, purify and enrich ephedrine and pseudoephedrine in human urine sample. With HF - LPME device, the extraction conditions were optimized. Under the optimal conditions using n-octyl alcohol as organic phase impregnated in the pores of hollow fiber, and acidic mi-croliter solution(pH 2. 0)as acceptor phase, the enrichment factors of 180 for ephedrine and 220 for pseudoephedrine were obtained at room temperature with extraction time of 60 min. The calibration curves were linear in the ranges of 0. 01-5 mg/L and 0. 005 -0. 75 mg/L for ephedrine and pseudoephedrine , with their correlation coefficients of 0. 998 2 and 0. 997 8, respectively. The limits of quantitation(S/N = 10) were 0. 01 mg/L and 0. 005 mg/L, respectively. With the advantages of low organic solvent consumption and high extraction efficiency, the method was suitable for the simultaneous determination of ephedrine and pseudoephedrine in urine sample.

  13. 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.

  14. 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...

  15. 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.

  16. 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...

  17. 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.

  18. A quantum mechanics/molecular dynamics study of electric field gradient fluctuations in the liquid phase. The case of Na+ in aqueous solution.

    Science.gov (United States)

    Aidas, Kęstutis; Ågren, Hans; Kongsted, Jacob; Laaksonen, Aatto; Mocci, Francesca

    2013-02-07

    The (23)Na quadrupolar coupling constant of the Na(+) ion in aqueous solution has been predicted using molecular dynamics simulations and hybrid quantum mechanics/molecular mechanics methods for the calculation of electric field gradients. The developed computational approach is generally expected to provide reliable estimates of the quadrupolar coupling constants of monoatomic species in condensed phases, and we show here that intermolecular polarization and non-electrostatic interactions are of crucial importance as they result in a 100% increased quadrupolar coupling constant of the ion as compared to a simpler pure electrostatic picture. These findings question the reliability of the commonly applied classical Sternheimer approximation for the calculations of the electric field gradient. As it can be expected from symmetry considerations, the quadrupolar coupling constants of the 5- and 6-coordinated Na(+) ions in solution are found to differ significantly.

  19. 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...

  20. 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...

  1. Solid-phase microextraction

    DEFF Research Database (Denmark)

    Nilsson, Torben

    The objective of this study has been to develop new analytical methods using the rapid, simple and solvent-free extraction technique solid-phase microextraction (SPME) for the quantitative analysis of organic pollutants at trace level in drinking water and environmental samples. The dynamics...

  2. 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)

  3. 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.

  4. 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.

  5. 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.

  6. Development of a dynamic headspace solid-phase microextraction procedure coupled to GC–qMSD for evaluation the chemical profile in alcoholic beverages

    OpenAIRE

    Rodrigues, F.; Caldeira, M; Câmara, José de Sousa

    2008-01-01

    In the present study, a simple and sensitive methodology based on dynamic headspace solid-phase microextraction (HS-SPME) followed by thermal desorption gas chromatography with quadrupole mass detection (GC–qMSD), was developed and optimized for the determination of volatile (VOCs) and semi-volatile (SVOCs) compounds from different alcoholic beverages: wine, beer and whisky. Key experimental factors influencing the equilibrium of the VOCs and SVOCs between the sample and the SPME fibre, as th...

  7. Membrane-based microextraction techniques in analytical chemistry: A review.

    Science.gov (United States)

    Carasek, Eduardo; Merib, Josias

    2015-06-23

    The use of membrane-based sample preparation techniques in analytical chemistry has gained growing attention from the scientific community since the development of miniaturized sample preparation procedures in the 1990s. The use of membranes makes the microextraction procedures more stable, allowing the determination of analytes in complex and "dirty" samples. This review describes some characteristics of classical membrane-based microextraction techniques (membrane-protected solid-phase microextraction, hollow-fiber liquid-phase microextraction and hollow-fiber renewal liquid membrane) as well as some alternative configurations (thin film and electromembrane extraction) used successfully for the determination of different analytes in a large variety of matrices, some critical points regarding each technique are highlighted.

  8. On-line extraction and determination of two herbicides: comparison between two modes of three-phase hollow fiber microextraction.

    Science.gov (United States)

    Tajik, Mohammad; Yamini, Yadollah; Esrafili, Ali; Ebrahimpour, Behnam

    2015-02-01

    Two different modes of three-phase hollow fiber liquid-phase microextraction were studied for the extraction of two herbicides, bensulfuron-methyl and linuron. In these two modes, the acceptor phases in the lumen of the hollow fiber were aqueous and organic solvents. The extraction and determination were performed using an automated hollow fiber microextraction instrument followed by high-performance liquid chromatography. For both three-phase hollow fiber liquid-phase microextraction modes, the effect of the main parameters on the extraction efficiency were investigated and optimized by central composite design. Under optimal conditions, both modes showed good linearity and repeatability, but the three-phase hollow fiber liquid-phase microextraction based on two immiscible organic solvents has a better extraction efficiency and figures of merit. The calibration curves for three-phase hollow fiber liquid-phase microextraction with an organic acceptor phase were linear in the range of 0.3-200 and 0.1-150 μg/L and the limits of detection were 0.1 and 0.06 μg/L for bensulfuron-methyl and linuron, respectively. For the conventional three-phase hollow fiber liquid-phase microextraction, the calibration curves were linear in the range of 3.0-250 and 15-400 μg/L and LODs were 1.0 and 5.0 μg/L for bensulfuron-methyl and linuron, respectively. The real sample analysis was carried out by three-phase hollow fiber liquid phase microextraction based on two immiscible organic solvents because of its more favorable characteristics.

  9. [Analysis of headspace constituents of Gardenia flower by GC/MS with solid-phase microextraction and dynamic headspace sampling].

    Science.gov (United States)

    Liu, B Z; Gao, Y

    2000-09-01

    The headspace constituents of fresh Gardenia flower were investigated by GC/MS. The headspace volatiles were sampled by solid-phase microextraction (SPME) and dynamic headspace sampling (DHS). SPME sampling was conducted with 100 microns PDMS fiber at 28 degrees C for 60 min. In DHS sampling, purified nitrogen was used as purging gas with a flow rate at 80 mL/min for 120 min. Tenax GR(20 mesh-40 mesh) was used as adsorbent and the volatiles were eluted by ether, and concentrated to 0.5 mL for GC/MS analysis. A Supelco-wax capillary column (30 m x 0.25 mm i.d. x 0.25 micron df) was employed in GC/MS analysis. Initial oven temperature was kept at 45 degrees C for 2 min, then raised to 250 degrees C at 4 degrees C/min, and kept at 250 degrees C for 10 min. According to SPME-GC/MS analysis, the main compounds in headspace of fresh Gardenia flower included farnesene(64.86%), cis-ocimene(29.33%), linalool(2.74%), cis-3-hexenyl tiglate(1.34%), methyl benzoate(0.25%). Results obtained from SPME and DHS sampling were also compared. In this study, SPME afforded a simpler and more sensitive sampling method, and much more accurate information about headspace volatiles of Gardenia flower.

  10. Comparison between dynamic headspace and headspace solid-phase microextraction for gas chromatography of BTEX in urine.

    Science.gov (United States)

    Brcić Karaconji, Irena; Skender, Ljiljana

    2007-12-01

    The aim of this study was to compare two extraction procedures: dynamic headspace-purge and trap (PT) and headspace solid-phase microextraction (HS-SPME) for gas chromatographic determination of benzene, toluene, ethylbenzene, and isomeric xylenes (BTEX) in urine with photoionization (PID) and mass spectrometric (MS) detection, respectively. Both methods showed linearity in the range of interest [(50-2000) ng L-1], good accuracy (80% to 100%), and repeatability (RSD< or =11%). Detection limits were in the low ng L-1 level for both methods, although slightly greater sensitivity was found for the PT method. In comparison with PT, HS-SPME was simpler and required less time for analysis. Although the analytical features of both examined methods are appropriate for biomonitoring of environmental exposure to BTEX, only the HS-SPME-GC-MS method is recommended for routine analysis of BTEX in urine. The method was applied for the quantitative analysis of BTEX in urine samples collected from non-smokers (n=10) and smokers (n=10).

  11. 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

  12. 微波辅助-顶空液相微萃取/高效液相色谱分析水样中的邻硝基苯酚%Determination of 2-Nitrophenol in Water by Microwave-Assisted Headspace-Liquid-Phase Microextraction Coupled with High Performance Liquid Chromatography

    Institute of Scientific and Technical Information of China (English)

    孔娜; 邹小兵; 黄锐; 魏欣旸

    2011-01-01

    建立了基于微波辅助-顶空液相微萃取在线联用、高效液相色谱法测定水样中邻硝基苯酚的分析方法。采用L16(45)正交实验设计对影响萃取的各种因素,如萃取有机溶剂、微波辐射功率、萃取时间、离子强度、样品液体积,进行了优化。优化后萃取条件为,以乙酸丁酯作为萃取溶剂,功率和时间分别为100W和12min条件下,离子强度为0的样品溶液体积为20mL。在优化萃取条件下,邻硝基苯酚的检出限LOD(S/N=3)为0.94μg/L,萃取富集倍数为30,实际水样的加标回收率为85.2%。理论分析和实验结果表明,微波辅助-顶空液相微萃取在线联用方法具有简便、快速、高效、节省溶剂、选择性好、应用范围广的特点。%The method for the determination of 2-Nitrophenol in environmental water samples had been developed using microwave-assisted-headspace-liquid-phase microextraction(MA-HS-LPME) coupled with high performance liquid chromatography(HPLC).The variable experimental conditions for the MA-HS-LPME extraction process,including extraction solvent,microwave irradiation power,extraction time,contents of inorganic salt and sample volume,were optimized by L16(45) orthogonal design.The optimized method was as following: butyl acetate as organic drop,20 mL aqueous sample without NaCl addition extracting for 12 min under microwave irradiation power 100 W.Under the optimized conditions,low detection limit(S/N=3) and the enrichment factor of the method for the target compound were 0.94μg/L and 30,respectively.The recoveries of target analyte spiked real water samples were 85.2%.The results indicated that the developed method is simple,rapid,efficient,solvent-saving,highly selective and widely applicable.

  13. 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.

  14. 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)

  15. 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.

  16. 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.

  17. Determination of steroid hormones in biological and environmental samples using green microextraction techniques: an overview.

    Science.gov (United States)

    Aufartová, Jana; Mahugo-Santana, Cristina; Sosa-Ferrera, Zoraida; Santana-Rodríguez, José Juan; Nováková, Lucie; Solich, Petr

    2011-10-17

    Residues of steroid hormones have become a cause for concern because they can affect the biological activity of non-target organisms. Steroid hormones are a potential risk for wildlife and humans through the consumption of contaminated food or water. Their determination requires extraction and clean-up steps, prior to detection, to reach low concentration levels. In recent years, a great effort has been made to develop new analytical methodologies, such as microextraction techniques, that reduce environmental pollution. Researchers have modified old methods to incorporate procedures that use less-hazardous chemicals or that use smaller amounts of them. They are able to do direct analysis using miniaturised equipment and reduced amounts of solvents and wastes. These accomplishments are the main objectives of green analytical chemistry. In this overview, we focus on microextraction techniques for the determination of steroid hormones in biological (e.g., human urine, human serum, fish, shrimp and prawn tissue and milk) and environmental (e.g., wastewaters, surface waters, tap waters, river waters, sewage sludges, marine sediments and river sediments) samples. We comment on the most recent applications in sorptive-microextraction modes, such as solid phase microextraction (SPME) with molecularly imprinted polymers (MIPs), in-tube solid-phase microextraction (IT-SPME), stir-bar sorptive extraction (SBSE) and microextraction in packed sorbent (MEPS). We also describe liquid-phase microextraction (LPME) approaches reported in the literature that are applied to the determination of steroid hormones.

  18. Solid-liquid phase equilibria of the Gaussian core model fluid.

    Science.gov (United States)

    Mausbach, Peter; Ahmed, Alauddin; Sadus, Richard J

    2009-11-14

    The solid-liquid phase equilibria of the Gaussian core model are determined using the GWTS [J. Ge, G.-W. Wu, B. D. Todd, and R. J. Sadus, J. Chem. Phys. 119, 11017 (2003)] algorithm, which combines equilibrium and nonequilibrium molecular dynamics simulations. This is the first reported use of the GWTS algorithm for a fluid system displaying a reentrant melting scenario. Using the GWTS algorithm, the phase envelope of the Gaussian core model can be calculated more precisely than previously possible. The results for the low-density and the high-density (reentrant melting) sides of the solid state are in good agreement with those obtained by Monte Carlo simulations in conjunction with calculations of the solid free energies. The common point on the Gaussian core envelope, where equal-density solid and liquid phases are in coexistence, could be determined with high precision.

  19. Computer simulations on the gas-liquid phase diagram of Stockmayer fluids

    Institute of Scientific and Technical Information of China (English)

    L(U) Zhongyuan; OUYANG Wenze; SUN Zhaoyan; LI Zesheng; AN Lijia

    2005-01-01

    Particle exchange molecular dynamics (PEMD) simulation technique is proposed to study the gas-liquid phase diagram of fluids. In the simulations, the fluid particles can be transferred between the two coupled boxes, which possess constant total number of particles and volume. The particle transfer is controlled by the difference of chemical potential in the respective simulation box. After equilibrium the two boxes have the same pressure, temperature and chemical potential. The method is further used to study the gas-liquid phase diagram of Stockmayer fluid. Increasing the dipole strength will enhance the critical temperature. The predicted critical points are in agreement with those from Gibbs ensemble Monte Carlo simulations, while the small systematic difference is attributed to the system size effects and the thermostat methods.

  20. 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.

  1. Time resolved infrared spectroscopy of femtosecond proton dynamics in the liquid phase; Spectroscopie infrarouge resolue en temps pour l'etude de la dynamique femtoseconde du proton en phase liquide

    Energy Technology Data Exchange (ETDEWEB)

    Amir, W

    2003-12-15

    This work of thesis aims to understand the strong mobility of protons in water. Water is fundamental to life and mediates many chemical and biological processes. However this liquid is poorly understood at the molecular level. The richness of interdisciplinary sciences allows us to study the properties which make it so unique. The technique used for this study was the femtosecond time resolved vibrational spectroscopy. Several experiments were carried out to characterize the femtosecond proton dynamics in water. The visualization of the rotation of water molecules obtained by anisotropy measurements will be presented. This experiment is carried out in isotopic water HDO/D{sub 2}O for reasons of experimental and theoretical suitability. However this is not water. Pure water H{sub 2}O was also studied without thermal effects across vibrations modes. An intermolecular energy resonant transfer was observed. Finally the localized structure of the proton in water (called Eigen form) was clearly experimentally observed. This molecule is implicated in the abnormal mobility of the proton in water (Grotthuss mechanism). (author)

  2. Beyond dispersive liquid-liquid microextraction.

    Science.gov (United States)

    Leong, Mei-I; Fuh, Ming-Ren; Huang, Shang-Da

    2014-03-28

    Dispersive liquid-liquid microextraction (DLLME) and other dispersion liquid-phase microextraction (LPME) methods have been developed since the first DLLME method was reported in 2006. DLLME is simple, rapid, and affords high enrichment factor, this is due to the large contact surface area of the extraction solvent. DLLME is a method suitable for the extraction in many different water samples, but it requires using chlorinated solvents. In recent years, interest in DLLME or dispersion LPME has been focused on the use of low-toxicity solvents and more conveniently practical procedures. This review examines some of the most interesting developments in the past few years. In the first section, DLLME methods are separated in two categories: DLLME with low-density extraction solvent and DLLME with high-density extraction solvent. Besides these methods, many novel special devices for collecting low-density extraction solvent are also mentioned. In addition, various dispersion techniques with LPME, including manual shaking, air-assisted LPME (aspirating and injecting the extraction mixture by syringe), ultrasound-assisted emulsification, vortex-assisted emulsification, surfactant-assisted emulsification, and microwave-assisted emulsification are described. Besides the above methods, combinations of DLLME with other extraction techniques (solid-phase extraction, stir bar sorptive extraction, molecularly imprinted matrix solid-phase dispersion and supercritical fluid extraction) are introduced. The combination of nanotechnique with DLLME is also introduced. Furthermore, this review illustrates the application of DLLME or dispersion LPME methods to separate and preconcentrate various organic analytes, inorganic analytes, and samples.

  3. 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.[¤

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. Investigating Processes of Materials Formation via Liquid Phase and Cryogenic TEM

    Energy Technology Data Exchange (ETDEWEB)

    De Yoreo, James J.; Sommerdijk, Nico

    2016-06-14

    The formation of materials in solutions is a widespread phenomenon in synthetic, biological and geochemical systems, occurring through dynamic processes of nucleation, self-assembly, crystal growth, and coarsening. The recent advent of liquid phase TEM and advances in cryogenic TEM are transforming our understanding of these phenomena by providing new insights into the underlying physical and chemical mechanisms. The techniques have been applied to metallic and semiconductor nanoparticles, geochemical and biological minerals, electrochemical systems, macromolecular complexes, and selfassembling systems, both organic and inorganic. New instrumentation and methodologies currently on the horizon promise new opportunities for advancing the science of materials synthesis.

  9. Automated dynamic hollow fiber liquid-liquid-liquid microextraction combined with capillary electrophoresis for speciation of mercury in biological and environmental samples.

    Science.gov (United States)

    Li, Pingjing; He, Man; Chen, Beibei; Hu, Bin

    2015-10-01

    A simple home-made automatic dynamic hollow fiber based liquid-liquid-liquid microextraction (AD-HF-LLLME) device was designed and constructed for the simultaneous extraction of organomercury and inorganic mercury species with the assistant of a programmable flow injection analyzer. With 18-crown-6 as the complexing reagent, mercury species including methyl-, ethyl-, phenyl- and inorganic mercury were extracted into the organic phase (chlorobenzene), and then back-extracted into the acceptor phase of 0.1% (m/v) 3-mercapto-1-propanesulfonic acid (MPS) aqueous solution. Compared with automatic static (AS)-HF-LLLME system, the extraction equilibrium of target mercury species was obtained in shorter time with higher extraction efficiency in AD-HF-LLLME system. Based on it, a new method of AD-HF-LLLME coupled with large volume sample stacking (LVSS)-capillary electrophoresis (CE)/UV detection was developed for the simultaneous analysis of methyl-, phenyl- and inorganic mercury species in biological samples and environmental water. Under the optimized conditions, AD-HF-LLLME provided high enrichment factors (EFs) of 149-253-fold within relatively short extraction equilibrium time (25min) and good precision with RSD between 3.8 and 8.1%. By combining AD-HF-LLLME with LVSS-CE/UV, EFs were magnified up to 2195-fold and the limits of detection (at S/N=3) for target mercury species were improved to be sub ppb level.

  10. Comparison of solid-phase microextraction and dynamic headspace methods for the gas chromatographic-mass spectrometric analysis of light-induced lipid oxidation products in milk.

    Science.gov (United States)

    Marsili, R T

    1999-01-01

    A sensitive, rapid procedure for testing lipid oxidation products in milk is developed using solid-phase microextraction (SPME) and gas chromatography-mass spectrometry. SPME is as sensitive as dynamic headspace (DH) analysis for measuring the pentanal and hexanal produced in milk after exposure to light. Furthermore, compared with DH, SPME is less expensive and demonstrates better precision and accuracy. In addition, SPME does not exhibit carryover or septa artifact peaks. The linearity of calibration curves (based on the method of additions technique with an internal standard) is consistently better for SPME than for DH. Furthermore, replicate analyses of pentanal and hexanal spiked in skim milk and 2% milk at 2 ng/mL demonstrate significantly lower coefficients of variation using SPME. To further test the practicality of SPME for measuring light-induced chemical changes in milk, 2% milk and skim milk samples are exposed to fluorescent light (200 foot-candles) for 0, 3, 6, 9, 12, 17, 24, and 48 h and analyzed by SPME and DH. Pentanal and hexanal in all samples are measured by SPME and DH. Correlation coefficients of resulting plots indicate that SPME is more accurate than DH in measuring the quantity of lipid oxidation products in milk.

  11. 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.

  12. 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%.

  13. 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...

  14. 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

  15. 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. 

  16. 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.

  17. 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.

  18. 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...

  19. 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.

  20. 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 ...

  1. 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.

  2. Automated dynamic headspace organic solvent film microextraction for benzene, toluene, ethylbenzene and xylene. Renewable liquid film as a sampler by a programmable motor.

    Science.gov (United States)

    Mohammadi, Abdorreza; Alizadeh, Naader

    2006-02-24

    A simple, fast and efficient dynamic headspace-organic solvent film microextraction (DHS-OSFME) method using a new automatic device was developed. The renewable organic films were formed inside a microsyringe barrel using the uniform and repeated movement of the syringe plunger enabled by programmable stirring motor. The plunger speed, number of extraction cycles, and dwell time (stop time after each half round) were controlled by a computer software, which was written by C++ Builder. A theoretical treatment of the DHS-OSFME based on the consecutive first-order process is proposed in this report. A mathematical solution for the dynamic process of the mass transfer was obtained by correlating the variation of analyte concentration in the syringe volume with the plunger speed and the amount of analyte extracted to the OSF. Benzene, toluene, ethylbenzene, and o-xylene (BTEX) were employed as model compounds to assess the extraction procedure and were determined by gas chromatography-flame ionization detection. Of the three organic solvents (1-octanol, benzyl alcohol and n-dodecane) studied as extractants, n-dodecane proved to be the most sensitive solvent for the extraction of these analytes. Several parameters, including the syringe withdrawal rate, dwelling time, number of extraction cycles, sampling volume, sample temperature, and ionic strength of the solution, were investigated for their effects on the extraction performance. The calibration graphs were linear in the range of 0.5-200 ng ml(-1), with the detection limits between 0.18 and 0.35 ng ml(-1). Wastewater samples were extracted by the optimized method, and determined using the standard addition method.

  3. Determination of Trace Amounts of Lead with ETAAS After Single Drop Microextraction and Dispersive Liquid Liquid Microextraction Methods

    Directory of Open Access Journals (Sweden)

    Efeçınar M.

    2013-04-01

    Full Text Available Two liquid-phase microextraction procedures, single-drop microextraction (SDME and dispersive liquid–liquid microextraction (DLLME, have been developed for the determination of lead by electrothermal atomic absorption spectrometry (ETAAS. Both methods were based on the formation of lead iodide-Rhodamine B complex which is in phosphoric acid medium. In the presence of KI, anionic lead iodide was complexed with Rhodamine B as an ion-association complex. Several factors that may be affected on the SDME and DLLME methods were optimized. In the optimum experimental conditions, the limit of detection (3s and the enhancement factor were 0.008 μgL−1 and 152 for SDME and 0.0129 μgL−1 and 89 for DLLME respectively. The relative standard deviation (RSD for eight replicate determinations of 0.25 μgL−1 Pb was 4.6% for SDME and 0.5 μgL−1 Pb was 2.9% for DLLME. The developed methods were validated by the analysis of certified reference materials, and applied successfully to the determination of lead in several water and food samples.

  4. 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.

  5. 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.

  6. 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 ...

  7. 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.

  8. 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.

  9. 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...

  10. 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

  11. 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.

  12. On-line sample processing involving microextraction techniques as a front-end to atomic spectrometric detection for trace metal assays: A review

    Energy Technology Data Exchange (ETDEWEB)

    Miró, Manuel, E-mail: manuel.miro@uib.es [FI-TRACE Group, Department of Chemistry, Faculty of Sciences, University of the Balearic Islands, E-07122 Palma de Mallorca, Illes Balears (Spain); Hansen, Elo Harald [Granåsen 93, DK-2800 Kgs. Lyngby (Denmark)

    2013-06-11

    Graphical abstract: -- Highlights: •Role of flow injection in automation of microextraction techniques for metal assays. •On-line coupling of liquid phase microextraction (LPME) to atomic spectrometry. •Critical evaluation of on-line single drop and dispersive LPME. •On-line coupling of micro-solid phase extraction (μSPE) to atomic spectrometry. •Critical appraisal of magnetic/carbon nanoparticles and biomass for on-line μSPE. -- Abstract: Within the last decade, liquid-phase microextraction (LPME) and micro-solid phase extraction (μSPE) approaches have emerged as substitutes for conventional sample processing procedures for trace metal assays within the framework of green chemistry. This review surveys the progress of the state of the art in simplification and automation of microextraction approaches by harnessing to the various generations of flow injection (FI) as a front end to atomic absorption spectrometry (AAS), atomic fluorescence spectrometry (AFS) or inductively coupled plasma atomic emission spectrometry or mass spectrometry (ICP-AES/MS). It highlights the evolution of flow injection analysis and related techniques as vehicles for appropriate sample presentation to the detector and expedient on-line matrix separation and pre-concentration of trace levels of metals in troublesome matrices. Rather than being comprehensive this review is aimed at outlining the pros and cons via representative examples of recent attempts in automating green sample preparation procedures in an FI or sequential injection (SI) mode capitalizing on single-drop microextraction, dispersive liquid-phase microextraction and advanced sorptive materials including carbon and metal oxide nanoparticles, ion imprinted polymers, superparamagnetic nanomaterials and biological/biomass sorbents. Current challenges in the field are identified and the synergetic combination of flow analysis, nanotechnology and metal-tagged biomolecule detection is envisaged.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Polarization-modulation infrared reflection-absorption spectroscopy affording time-resolved simultaneous detection of surface and liquid phase species at catalytic solid-liquid interfaces.

    Science.gov (United States)

    Meier, Daniel M; Urakawa, Atsushi; Baiker, Alfons

    2009-09-01

    Polarization-modulation infrared reflection-absorption spectroscopy (PM-IRRAS) combined with concentration modulation allows simultaneous monitoring of dynamic evolutions of surface and liquid phase species during reactions at catalytic interfaces as demonstrated for the Pt-catalysed oxidation of CO by O2 in cyclohexane.

  1. Development of a dynamic headspace solid-phase microextraction procedure coupled to GC-qMSD for evaluation the chemical profile in alcoholic beverages

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, F.; Caldeira, M. [Centro de Quimica da Madeira, Departamento de Quimica, Universidade da Madeira, Campus Universitario da Penteada, 9000-390 Funchal (Portugal); Camara, J.S. [Centro de Quimica da Madeira, Departamento de Quimica, Universidade da Madeira, Campus Universitario da Penteada, 9000-390 Funchal (Portugal)], E-mail: jsc@uma.pt

    2008-02-18

    In the present study, a simple and sensitive methodology based on dynamic headspace solid-phase microextraction (HS-SPME) followed by thermal desorption gas chromatography with quadrupole mass detection (GC-qMSD), was developed and optimized for the determination of volatile (VOCs) and semi-volatile (SVOCs) compounds from different alcoholic beverages: wine, beer and whisky. Key experimental factors influencing the equilibrium of the VOCs and SVOCs between the sample and the SPME fibre, as the type of fibre coating, extraction time and temperature, sample stirring and ionic strength, were optimized. The performance of five commercially available SPME fibres was evaluated and compared, namely polydimethylsiloxane (PDMS, 100 {mu}m); polyacrylate (PA, 85 {mu}m); polydimethylsiloxane/divinylbenzene (PDMS/DVB, 65 {mu}m); carboxen{sup TM}/polydimethylsiloxane (CAR/PDMS, 75 {mu}m) and the divinylbenzene/carboxen on polydimethylsiloxane (DVB/CAR/PDMS, 50/30 {mu}m) (StableFlex). An objective comparison among different alcoholic beverages has been established in terms of qualitative and semi-quantitative differences on volatile and semi-volatile compounds. These compounds belong to several chemical families, including higher alcohols, ethyl esters, fatty acids, higher alcohol acetates, isoamyl esters, carbonyl compounds, furanic compounds, terpenoids, C13-norisoprenoids and volatile phenols. The optimized extraction conditions and GC-qMSD, lead to the successful identification of 44 compounds in white wines, 64 in beers and 104 in whiskys. Some of these compounds were found in all of the examined beverage samples. The main components of the HS-SPME found in white wines were ethyl octanoate (46.9%), ethyl decanoate (30.3%), ethyl 9-decenoate (10.7%), ethyl hexanoate (3.1%), and isoamyl octanoate (2.7%). As for beers, the major compounds were isoamyl alcohol (11.5%), ethyl octanoate (9.1%), isoamyl acetate (8.2%), 2-ethyl-1-hexanol (5.9%), and octanoic acid (5.5%). Ethyl

  2. Development of a dynamic headspace solid-phase microextraction procedure coupled to GC-qMSD for evaluation the chemical profile in alcoholic beverages.

    Science.gov (United States)

    Rodrigues, F; Caldeira, M; Câmara, J S

    2008-02-18

    In the present study, a simple and sensitive methodology based on dynamic headspace solid-phase microextraction (HS-SPME) followed by thermal desorption gas chromatography with quadrupole mass detection (GC-qMSD), was developed and optimized for the determination of volatile (VOCs) and semi-volatile (SVOCs) compounds from different alcoholic beverages: wine, beer and whisky. Key experimental factors influencing the equilibrium of the VOCs and SVOCs between the sample and the SPME fibre, as the type of fibre coating, extraction time and temperature, sample stirring and ionic strength, were optimized. The performance of five commercially available SPME fibres was evaluated and compared, namely polydimethylsiloxane (PDMS, 100 microm); polyacrylate (PA, 85 microm); polydimethylsiloxane/divinylbenzene (PDMS/DVB, 65 microm); carboxentrade mark/polydimethylsiloxane (CAR/PDMS, 75 microm) and the divinylbenzene/carboxen on polydimethylsiloxane (DVB/CAR/PDMS, 50/30 microm) (StableFlex). An objective comparison among different alcoholic beverages has been established in terms of qualitative and semi-quantitative differences on volatile and semi-volatile compounds. These compounds belong to several chemical families, including higher alcohols, ethyl esters, fatty acids, higher alcohol acetates, isoamyl esters, carbonyl compounds, furanic compounds, terpenoids, C13-norisoprenoids and volatile phenols. The optimized extraction conditions and GC-qMSD, lead to the successful identification of 44 compounds in white wines, 64 in beers and 104 in whiskys. Some of these compounds were found in all of the examined beverage samples. The main components of the HS-SPME found in white wines were ethyl octanoate (46.9%), ethyl decanoate (30.3%), ethyl 9-decenoate (10.7%), ethyl hexanoate (3.1%), and isoamyl octanoate (2.7%). As for beers, the major compounds were isoamyl alcohol (11.5%), ethyl octanoate (9.1%), isoamyl acetate (8.2%), 2-ethyl-1-hexanol (5.9%), and octanoic acid (5

  3. Liquid Phase – Pulsed Laser Ablation: A route to fabricate different carbon nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Al-Hamaoy, Ahmed [Advanced Processing Technology Research Centre, Dublin City University, Dublin 9 (Ireland); Institute of Laser for Postgraduate Studies, University of Baghdad (Iraq); Mechanical Engineering Department, College of Engineering, University of Anbar (Iraq); Chikarakara, Evans [Advanced Processing Technology Research Centre, Dublin City University, Dublin 9 (Ireland); Jawad, Hussein [Institute of Laser for Postgraduate Studies, University of Baghdad (Iraq); Gupta, Kapil; Kumar, Dinesh; Rao, M.S. Ramachandra [Department of Physics, Nano Functional Materials Technology Centre and Materials Science Research Centre, Indian Institute of Technology (IIT) Madras, Chennai 600 036 (India); Krishnamurthy, Satheesh [Materials Engineering, The Open University, Milton Keynes, MK7 6AA (United Kingdom); Morshed, Muhammad [Advanced Processing Technology Research Centre, Dublin City University, Dublin 9 (Ireland); Fox, Eoin; Brougham, Dermot [School of Chemical Sciences, Dublin City University, Dublin 9 (Ireland); He, Xiaoyun; Vázquez, Mercedes [Advanced Processing Technology Research Centre, Dublin City University, Dublin 9 (Ireland); Irish Separation Science Cluster (ISSC) National Centre for Sensor Research, Dublin City University, Dublin 9 (Ireland); Brabazon, Dermot, E-mail: dermot.brabazon@dcu.ie [Advanced Processing Technology Research Centre, Dublin City University, Dublin 9 (Ireland); Irish Separation Science Cluster (ISSC) National Centre for Sensor Research, Dublin City University, Dublin 9 (Ireland)

    2014-05-01

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

  4. Toward a universal water model: First principles simulations from the dimer to the liquid phase

    CERN Document Server

    Babin, Volodymyr; Paesani, Francesco

    2012-01-01

    A full-dimensional molecular model of water, HBB2-pol, derived entirely from first principles, is introduced and employed in computer simulations ranging from the dimer to the liquid. HBB2-pol provides excellent agreement with the measured second and third virial coefficients and, by construction, reproduces the dimer vibration-rotation tunneling spectrum. The model also predicts the relative energy differences between isomers of small water clusters within the accuracy of highly correlated electronic structure methods. Importantly, when combined with simulation methods that explicitly include zero-point energy and quantum thermal motion, HBB2-pol accurately describes both structural and dynamical properties of the liquid phase. The predictive power of the HBB2-pol quantum simulations opens the door to the long-sought molecular-level understanding of water under different conditions and in different environments.

  5. Stability analysis of whirling composite shells partially filled with two liquid phases

    Energy Technology Data Exchange (ETDEWEB)

    Sahebnasagh, Mohammad [Department of Mechanical Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Nikkhah-Bahrami, Mansour; Firouz-Abadi, Roohollah [Department of Aerospace Engineering, Sharif University, Tehran (Iran, Islamic Republic of)

    2017-05-15

    In this paper, the stability of whirling composite cylindrical shells partially filled with two liquid phases is studied. Using the first-order shear shell theory, the structural dynamics of the shell is modeled and based on the Navier-Stokes equations for ideal liquid, a 2D model is developed for liquid motion at each section of the cylinder. In steady state condition, liquids are supposed to locate according to mass density. In this study, the thick shells are investigated. Using boundary conditions between liquids, the model of coupled fluid-structure system is obtained. This coupled fluid-structure model is employed to determine the critical speed of the system. The effects of the main variables on the stability of the shell are studied and the results are investigated.

  6. Comparison of different methods: static and dynamic headspace and solid-phase microextraction for the measurement of interactions between milk proteins and flavor compounds with an application to emulsions.

    Science.gov (United States)

    Fabre, M; Aubry, V; Guichard, E

    2002-03-13

    Interactions between 10 aroma compounds from different chemical classes and 5 mixtures of milk proteins have been studied using static or dynamic headspace gas chromatography and solid-phase microextraction (SPME). Static headspace analysis allows the quantification of the release of only the most abundant compounds. Dynamic headspace analysis does not allow the discrimination of flavor release from the different protein mixtures, probably due to a displacement of headspace equilibrium. By SPME analysis and quantification by GC-MS (SIM mode) all of the volatiles were quantified. This method was optimized to better discriminate aroma release from the different milk protein mixtures and then from oil/water emulsions made with these proteins. The highest difference between the release in different proteins was observed for ethyl hexanoate, which has a great affinity for beta-lactoglobulin. Ethyl hexanoate is thus less released from models and emulsions containing this protein.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.)

  12. 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.

  13. 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.

  14. 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.

  15. Hydrogenation of nitriles on a well-characterized nickel surface: From surface science studies to liquid phase catalytic activity measurements

    Energy Technology Data Exchange (ETDEWEB)

    Gardin, D.E.

    1993-12-01

    Nitrile hydrogenation is the most commonly used method for preparing diverse amines. This thesis is aimed at the mechanism and factors affecting the performance of Ni-based catalysts in nitrile hydrogenations. Surface science techniques are used to study bonding of nitriles and amines to a Ni(111) surface and to identify surface intermediates. Liquid-phase hydrogenations of cyclohexene and 1-hexene on a Pt foil were carried out successfully. Finally, knowledge about the surface structure, surface chemical bond, dynamics of surface atoms (diffusion, growth), and reactivity of metal surfaces from solid-gas interface studies, is discussed.

  16. 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.

  17. Liquid-Phase Processing of Barium Titanate Thin Films

    Science.gov (United States)

    Harris, David Thomas

    . Our system exhibits flux-film-substrate interactions that can lead to dramatic changes to the microstructure. This effect is especially pronounced onc -sapphire, with Al diffusion from the substrate leading to formation of an epitaxial BaAl2O4 second phase at the substrate-film interface. The formation of this second phase in the presence of a liquid phase seeds {111} twins that drive abnormal grain growth. The orientation of the sapphire substrate determines the BaAl2O 4 morphology, enabling control the abnormal grain growth behavior. CuO additions leads to significant grain growth at 900 °C, with average grain size approaching 500 nm. The orthorhombic-tetragonal phase transition is clearly observable in temperature dependent measurements and both linear and nonlinear dielectric properties are improved. All films containing CuO are susceptible to aging. A number of other systems were investigated for efficacy at temperatures below 900 °C. Pulsed laser deposition was used to study flux + BaTiO 3 targets, layered flux films, and in situ liquids. RF-magnetron sputtering using a dual-gun approach was used to explore integration on flexible foils with Ba1-xSrxTiO3. Many of these systems were based on the BaO-B2O3 system, which has proven effective in thin films, multilayer ceramic capacitors, and bulk ceramics. Modifiers allow tailoring of the microstructure at 900 °C, however no compositions were found, and no reports exist in the open literature, that provide significant grain growth or densification below 900 °C. Liquid phase fluxes offer a promising path forward for low temperature processing of barium titanate, with the ultimate goal of integration with metalized silicon substrates. This work demonstrates significant improvements to dielectric properties and the necessity of understanding interactions in the film-flux-substrate system.

  18. 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.

  19. Third-order gas-liquid phase transition and the nature of Andrews critical point

    Directory of Open Access Journals (Sweden)

    Tian Ma

    2011-12-01

    Full Text Available The main objective of this article is to study the nature of the Andrews critical point in the gas-liquid transition in a physical-vapor transport (PVT system. A dynamical model, consistent with the van der Waals equation near the Andrews critical point, is derived. With this model, we deduce two physical parameters, which interact exactly at the Andrews critical point, and which dictate the dynamic transition behavior near the Andrews critical point. In particular, it is shown that 1 the gas-liquid co-existence curve can be extended beyond the Andrews critical point, and 2 the transition is first order before the critical point, second-order at the critical point, and third order beyond the Andrews critical point. This clearly explains why it is hard to observe the gas-liquid phase transition beyond the Andrews critical point. Furthermore, the analysis leads naturally the introduction of a general asymmetry principle of fluctuations and the preferred transition mechanism for a thermodynamic system. The theoretical results derived in this article are in agreement with the experimental results obtained in (K. Nishikawa and T. Morita, Fluid behavior at supercritical states studied by small-angle X-ray scattering, Journal of Supercritical Fluid, 13 (1998, pp. 143-148. Also, the derived second-order transition at the critical point is consistent with the result obtained in (M. Fisher, Specific heat of a gas near the critical point, Physical Review, 136:6A (1964, pp. A1599-A1604.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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

  5. The dependence of isobaric thermal heat capacity of gas condensates in liquid phase on their temperature

    Directory of Open Access Journals (Sweden)

    Bukhovich Y. V.

    2015-09-01

    Full Text Available The study of the thermo-physical properties of liquids gives an opportunity of qualitative and quantitative evaluation of condensed matter theory, phase transitions and critical phenomena. To forecast the thermo-dynamic properties of liquid natural hydrocarbons one must know the basic heat-physical characteristics in a wide range of condition parameters. We have researched specific isobaric thermal heat capacity of gas condensates of Oposhnyanskoye, Solokhovskoye, Bukharskoye, Rybalskoye, Stavropolskoye, Schebelinskoye and Yubileinoye deposits theoretically and experimentally. These substances were in liquid phase on pseudo-critical isobar in the range of temperatures from minus 40 till 100 °C. In the article the findings of the investigation are presented. The mean relative experimental error doesn’t exceed ± 1.5 %, with reliability 0.95. The universal equation expressing specific isobaric thermal heat capacity as the function of temperature and molar mass has been obtained. It describes specific isobaric thermal heat capacity on pseudo-critical isobar for investigated natural hydrocarbons with the mean relative error, which does not exceed ± 1.65 %. The use of the equation for the calculation of specific isobaric thermal heat capacity of the substances of other deposits is recommended

  6. Analysis of enantiomeric and non-enantiomeric monoterpenes in plant emissions using portable dynamic air sampling/solid-phase microextraction (PDAS-SPME) and chiral gas chromatography/mass spectrometry

    Science.gov (United States)

    Yassaa, Noureddine; Williams, Jonathan

    A portable dynamic air sampler (PDAS) using a porous polymer solid-phase microextraction (SPME) fibre has been validated for the determination of biogenic enantiomeric and non-enantiomeric monoterpenes in air. These compounds were adsorbed in the field, and then thermally desorbed at 250 °C in a gas chromatograph injector port connected via a β-cyclodextrin capillary separating column to a mass spectrometer. The optimized method has been applied for investigating the emissions of enantiomeric monoterpenes from Pseudotsuga menziesii (Douglas-fir), Rosmarinus officinalis (Rosemary) and Lavandula lanata (Lavender) which were selected as representative of coniferous trees and aromatic plants, respectively. The enantiomers of α-pinene, sabinene, camphene, δ-3-carene, β-pinene, limonene, β-phellandrene, 4-carene and camphor were successfully determined in the emissions from the three plants. While Douglas-fir showed a strong predominance toward (-)-enantiomers, Rosemary and Lavender demonstrated a large variation in enantiomeric distribution of monoterpenes. The simplicity, rapidity and sensitivity of dynamic sampling with porous polymer coated SPME fibres coupled to chiral capillary gas chromatography/mass spectrometry (GC/MS) makes this method potentially useful for in-field investigations of atmosphere-biosphere interactions and studies of optically explicit atmospheric chemistry.

  7. Evidence for a simple monatomic ideal glass former: the thermodynamic glass transition from a stable liquid phase.

    Science.gov (United States)

    Elenius, Måns; Oppelstrup, Tomas; Dzugutov, Mikhail

    2010-11-01

    Under cooling, a liquid can undergo a transition to the glassy state either as a result of a continuous slowing down or by a first-order polyamorphous phase transition. The second scenario has so far always been observed in a metastable liquid domain below the melting point where crystalline nucleation interfered with the glass formation. We report the first observation of the liquid-glass transition by a first-order polyamorphous phase transition from the equilibrium stable liquid phase. The observation was made in a molecular dynamics simulation of a one-component system with a model metallic pair potential. In this way, the model, demonstrating the thermodynamic glass transition from a stable liquid phase, may be regarded as a candidate for a simple monatomic ideal glass former. This observation is of conceptual importance in the context of continuing attempts to resolve the long-standing Kauzmann paradox. The possibility of a thermodynamic glass transition from an equilibrium melt in a metallic system also indicates a new strategy for the development of bulk metallic glass-forming alloys.

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

    Directory of Open Access Journals (Sweden)

    Peng Hao

    2011-01-01

    Full Text Available Abstract The migration characteristics of carbon nanotubes from liquid phase to vapor phase in the refrigerant-based nanofluid pool boiling were investigated experimentally. Four types of carbon nanotubes with the outside diameters from 15 to 80 nm and the lengths from 1.5 to 10 μm were used in the experiments. The refrigerants include R113, R141b and n-pentane. The oil concentration is from 0 to 10 wt.%, the heat flux is from 10 to 100 kW·m-2, and the initial liquid-level height is from 1.3 to 3.4 cm. The experimental results indicate that the migration ratio of carbon nanotube increases with the increase of the outside diameter or the length of carbon nanotube. For the fixed type of carbon nanotube, the migration ratio decreases with the increase of the oil concentration or the heat flux, and increases with the increase of the initial liquid-level height. The migration ratio of carbon nanotube increases with the decrease of dynamic viscosity of refrigerant or the increase of liquid phase density of refrigerant. A model for predicting the migration ratio of carbon nanotubes in the refrigerant-based nanofluid pool boiling is proposed, and the predictions agree with 92% of the experimental data within a deviation of ±20%.

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

    Science.gov (United States)

    2011-01-01

    The migration characteristics of carbon nanotubes from liquid phase to vapor phase in the refrigerant-based nanofluid pool boiling were investigated experimentally. Four types of carbon nanotubes with the outside diameters from 15 to 80 nm and the lengths from 1.5 to 10 μm were used in the experiments. The refrigerants include R113, R141b and n-pentane. The oil concentration is from 0 to 10 wt.%, the heat flux is from 10 to 100 kW·m-2, and the initial liquid-level height is from 1.3 to 3.4 cm. The experimental results indicate that the migration ratio of carbon nanotube increases with the increase of the outside diameter or the length of carbon nanotube. For the fixed type of carbon nanotube, the migration ratio decreases with the increase of the oil concentration or the heat flux, and increases with the increase of the initial liquid-level height. The migration ratio of carbon nanotube increases with the decrease of dynamic viscosity of refrigerant or the increase of liquid phase density of refrigerant. A model for predicting the migration ratio of carbon nanotubes in the refrigerant-based nanofluid pool boiling is proposed, and the predictions agree with 92% of the experimental data within a deviation of ±20%. PMID:21711730

  10. Evidence of the existence of the low-density liquid phase in supercooled, confined water.

    Science.gov (United States)

    Mallamace, Francesco; Broccio, Matteo; Corsaro, Carmelo; Faraone, Antonio; Majolino, Domenico; Venuti, Valentina; Liu, Li; Mou, Chung-Yuan; Chen, Sow-Hsin

    2007-01-09

    By confining water in a nanoporous structure so narrow that the liquid could not freeze, it is possible to study properties of this previously undescribed system well below its homogeneous nucleation temperature TH = 231 K. Using this trick, we were able to study, by means of a Fourier transform infrared spectroscopy, vibrational spectra (HOH bending and OH-stretching modes) of deeply supercooled water in the temperature range 183 < T < 273 K. We observed, upon decreasing temperature, the building up of a new population of hydrogen-bonded oscillators centered around 3,120 cm(-1), the contribution of which progressively dominates the spectra as one enters into the deeply supercooled regime. We determined that the fractional weight of this spectral component reaches 50% just at the temperature, TL approximately 225 K, where the confined water shows a fragile-to-strong dynamic cross-over phenomenon [Ito, K., Moynihan, C. T., Angell, C. A. (1999) Nature 398:492-494]. Furthermore, the fact that the corresponding OH stretching spectral peak position of the low-density-amorphous solid water occurs exactly at 3,120 cm(-1) [Sivakumar, T. C., Rice, S. A., Sceats, M. G. (1978) J. Chem. Phys. 69:3468-3476.] strongly suggests that these oscillators originate from existence of the low-density-liquid phase derived from the occurrence of the first-order liquid-liquid (LL) phase transition and the associated LL critical point in supercooled water proposed earlier by a computer molecular dynamics simulation [Poole, P. H., Sciortino, F., Essmann, U., Stanley, H. E. (1992) Nature 360:324-328].

  11. 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.

  12. 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.

  13. KINETIC STUDY OF LIQUID-PHASE ADSORPTIVE REMOVAL OF ...

    African Journals Online (AJOL)

    dried (Gallen Kamp, model OV-160, England) at 105 oC to constant weight and ... The physico-chemical characteristic of the adsorbent was determined using .... Since the solubility of a metal ion is an important factor, which ..... Weber Jr., W.J.; Digiano, F.O. Process Dynamics in Environmental System; Environmental.

  14. Volatile compounds in low-acid fermented sausage "espetec" and sliced cooked pork shoulder subjected to high pressure processing. A comparison of dynamic headspace and solid-phase microextraction.

    Science.gov (United States)

    Rivas-Cañedo, Ana; Juez-Ojeda, Cristina; Nuñez, Manuel; Fernández-García, Estrella

    2012-05-01

    Two extraction techniques, dynamic headspace extraction (DHE) and solid-phase microextraction (SPME), were compared to assess the effect of high-pressure treatment (400MPa, 10min, 12°C) on the volatile compounds of low-acid fermented sausage "espetec" and sliced cooked pork shoulder stored at 4°C. DHE was more efficient at extracting low-boiling compounds such as ethanal, 2,3-butanedione and alcohols, while SPME extracted more efficiently a higher number of chemical families, especially fatty acids. The effect of pressurisation on the volatile fraction of "espetec" was better categorized by DHE, whereas SPME was more appropriate for cooked pork shoulder. The volatile fraction of "espetec" changed slightly after pressurisation, mainly showing a decrease in the levels of lipid-derived compounds, like linear alkanes, aldehydes, or 1-alcohols in pressurised samples. The volatile profile of cooked pork shoulder underwent substantial changes during refrigerated storage, mainly due to microbial metabolism, most of these changes being limited by HPP.

  15. Recent development of supported monometallic gold as heterogeneous catalyst for selective liquid phase hydrogenation reactions

    Institute of Scientific and Technical Information of China (English)

    Thushara Kandaramath Hari; Zahira Yaakob

    2015-01-01

    The great potential of gold catalysts for chemical conversions in both industrial and environmental concerns has attracted increasing interest in many fields of research. Gold nanoparticles supported by metal oxides with high surface area have been recognized as highly efficient and effective green heterogeneous catalyst even at room temperature under normal reaction conditions, in gas and liquid phase reactions. In the present review, we dis-cuss the recent development of heterogeneous, supported monometal ic gold catalysts for organic transforma-tions emphasizing mainly liquid phase hydrogenation reactions. Discussions on the catalytic synthesis procedures and the promoting effect of other noble metals are omitted since they are already worked out. Appli-cations of heterogeneous, supported monometal ic catalysts for chemoselective hydrogenations in liquid phase are studied including potential articles during the period 2000–2013.

  16. 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.

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

    Science.gov (United States)

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

    2013-01-01

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

  18. Chemical studies of elements with Z ≥ 104 in liquid phase

    Energy Technology Data Exchange (ETDEWEB)

    Nagame, Yuichiro, E-mail: nagame.yuichiro@jaea.go.jp [Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki 319-1195 (Japan); Kratz, Jens Volker [Institut für Kernchemie, Johannes Gutenberg-Universität Mainz, Fritz-Straßmann-Weg 2, 55128 Mainz (Germany); Schädel, Matthias [Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki 319-1195 (Japan)

    2015-12-15

    Recent studies of the chemical separation and characterization experiments of the first three transactinide elements, rutherfordium (Rf), dubnium (Db), and seaborgium (Sg), conducted atom-at-a-time in liquid phases, are reviewed. A short description on experimental techniques based on partition methods, specifically automated rapid chemical separation systems, is also given. A newly developed experimental approach to investigate single atoms of the heaviest elements with an electrochemical method is introduced. Perspectives for liquid-phase chemistry experiments on heavier elements are briefly discussed.

  19. 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....

  20. Formation of Fermi surfaces and the appearance of liquid phases in holographic theories with hyperscaling violation

    CERN Document Server

    Kuang, Xiao-Mei; Wang, Bin; Wu, Jian-Pin

    2014-01-01

    We consider a holographic fermionic system in which the fermions are interacting with a U(1) gauge field in the presence of a dilaton field in the background of a charged black hole with hyperscaling violation. Using both analytical and numerical methods, we investigate the properties of the infrared and ultaviolet Green's functions of the holographic fermionic system. Studying the spectral functions of the system, we find that as the hyperscaling violation exponent is varied, the fermionic system possesses Fermi, non-Fermi, marginal-Fermi and log-oscillating liquid phases. Various liquid phases of the fermionic system with hyperscaling violation are also generated with the variation of the fermionic mass.

  1. Analytical study of the liquid phase transient behavior of a high temperature heat pipe

    Science.gov (United States)

    Roche, Gregory Lawrence

    1988-09-01

    The transient operation of the liquid phase of a high temperature heat pipe is studied. The study was conducted in support of advanced heat pipe applications that require reliable transport of high temperature drops and significant distances under a broad spectrum of operating conditions. The heat pipe configuration studied consists of a sealed cylindrical enclosure containing a capillary wick structure and sodium working fluid. The wick is an annular flow channel configuration formed between the enclosure interior wall and a concentric cylindrical tube of fine pore screen. The study approach is analytical through the solution of the governing equations. The energy equation is solved over the pipe wall and liquid region using the finite difference Peaceman-Rachford alternating direction implicit numerical method. The continuity and momentum equations are solved over the liquid region by the integral method. The energy equation and liquid dynamics equation are tightly coupled due to the phase change process at the liquid-vapor interface. A kinetic theory model is used to define the phase change process in terms of the temperature jump between the liquid-vapor surface and the bulk vapor. Extensive auxiliary relations, including sodium properties as functions of temperature, are used to close the analytical system. The solution procedure is implemented in a FORTRAN algorithm with some optimization features to take advantage of the IBM System/370 Model 3090 vectorization facility. The code was intended for coupling to a vapor phase algorithm so that the entire heat pipe problem could be solved. As a test of code capabilities, the vapor phase was approximated in a simple manner.

  2. Measurement of modulation induced by interaction between bubble motion and liquid-phase motion in the decaying turbulence formed by an oscillating-grid

    Institute of Scientific and Technical Information of China (English)

    Yasuyuki Nagami; Takayuki Saito

    2013-01-01

    In multiphase flows,dynamical gas-liquid interactions are essential for in-depth understanding of their multi-scale phenomena and complicated structures.The purpose of the present study is to clearly extract the modulation in bubble motion and liquid motion induced by bubble-liquid interaction and to discuss the relations between bubble motion and liquid-phase motion.For this particular purpose,the decaying turbulence formed in a cylindrical acrylic pipe (diameter 149 mm,height 600 mm) by using an oscillatinggrid was employed.Uniform single bubbles were launched from an in-house bubble launching device into the decaying turbulence.By comparing the bubble motion in the stagnant water with that in the oscillating-grid decaying turbulence,the transition of the 2D bubble motion (i.e.,zigzagging motion)to 3D motion was enhanced in the latter.In addition,the initial conditions of the bubble motion that was not influenced by the ambient turbulence were carefully confirmed.In the area where the bubble motion started to translate from 2D motion into 3D motion,the modulation of ambient liquid-phase motion was obtained by PIV/LIF measurement.By combining these results,we quantitatively discussed the modulation of the bubble motion and ambient liquid-phase motion and considered the dominant factor for the enhancement to be the bubble-liquid interaction.

  3. Multiple solid-phase microextraction

    NARCIS (Netherlands)

    Koster, EHM; de Jong, GJ

    2000-01-01

    Theoretical aspects of multiple solid-phase microextraction are described and the principle is illustrated with the extraction of lidocaine from aqueous solutions. With multiple extraction under non-equilibrium conditions considerably less time is required in order to obtain an extraction yield that

  4. Dynamic liquid-liquid-solid microextraction based on molecularly imprinted polymer filaments on-line coupling to high performance liquid chromatography for direct analysis of estrogens in complex samples.

    Science.gov (United States)

    Zhong, Qisheng; Hu, Yufei; Hu, Yuling; Li, Gongke

    2012-06-08

    A novel sample preparation technique termed dynamic liquid-liquid-solid microextraction (DLLSME) was developed and on-line coupled to high performance liquid chromatography (HPLC) for direct extraction, desorption, and analysis of trace estrogens in complex samples. The DLLSME consists of the aqueous donor phase, the organic medium phase and the molecularly imprinted polymer filaments (MIPFs) as solid acceptor phase. The organic solvent with lesser density was directly added on top of the aqueous sample, and the dynamic extraction was performed by circulating the organic solvent through the MIPFs inserted into a PEEK tube which served as an extraction and desorption chamber. Afterwards, the extracted analytes on the MIPFs were on-line desorbed and then introduced into the HPLC for analysis. To evaluate the feasibility of the on-line system, a new DLLSME-HPLC method was developed for the analysis of five estrogens in aqueous samples by using 17β-estradiol MIPFs as the solid phase. Under the optimized conditions, the enrichment factors of 51-70, limits of detection of 0.08-0.25 μg/L and precision within 4.5-6.9% were achieved. Furthermore, the proposed method was applied to the analysis of real samples including urine, milk and skin toner, satisfactory recovery (81.9-99.8%) and reproducibility (4.1-7.9%) were obtained. Especially, 0.59 μg/L of 17β-estradiol was determined in female urine sample. The DLLSME offers an attractive alternative for direct analysis of trace analytes in aqueous samples and could potentially be extended to other adsorptive materials.

  5. Dispersive suspended microextraction.

    Science.gov (United States)

    Yang, Zhong-Hua; Liu, Yu; Lu, Yue-Le; Wu, Tong; Zhou, Zhi-Qiang; Liu, Dong-Hui

    2011-11-14

    A novel sample pre-treatment technique termed dispersive suspended microextraction (DSME) coupled with gas chromatography-flame photometric detection (GC-FPD) has been developed for the determination of eight organophosphorus pesticides (ethoprophos, malathion, chlorpyrifos, isocarbophos, methidathion, fenamiphos, profenofos, triazophos) in aqueous samples. In this method, both extraction and two phases' separation process were performed by the assistance of magnetic stirring. After separating the two phases, 1 μL of the suspended phase was injected into GC for further instrument analysis. Varieties of experiment factors which could affect the experiment results were optimized and the following were selected: 12.0 μL p-xylene was selected as extraction solvent, extraction speed was 1200 rpm, extraction time was 30 s, the restoration speed was 800 rpm, the restoration time was 8 min, and no salt was added. Under the optimum conditions, limits of detections (LODs) varied between 0.01 and 0.05 μg L(-1). The relative standard deviation (RSDs, n=6) ranged from 4.6% to 12.1%. The linearity was obtained by five points in the concentration range of 0.1-100.0 μg L(-1). Correlation coefficients (r) varied from 0.9964 to 0.9995. The enrichment factors (EFs) were between 206 and 243. In the final experiment, the developed method has been successfully applied to the determination of organophosphorus pesticides in wine and tap water samples and the obtained recoveries were between 83.8% and 101.3%. Compared with other pre-treatment methods, DSME has its own features and could achieve satisfied results for the analysis of trace components in complicated matrices.

  6. 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...

  7. Liquid Phase Sintering of Carbides Using a Nickel-Molybdenum Alloy

    Science.gov (United States)

    1988-07-01

    AD TECHNICAL REPORT ARCCB-TR-88031 LIQUID PHASE SINTERING OF CARBIDES USING A NICKEL-MOL YBDENUM ALL 0 Y co J. M. BARRANCO mS R. A. WARENCHAK...ORG. REPORT NUMBER 7. AUTHOR(e) S. CONTRACT OR GRANT NUMBER,) J. M. Barranco and R. A. Warenchak 9. PERFORMING ORGANIZATION NAME AND ADDRESS 10

  8. Liquid phase demixing in ferroelectric/semiconducting polymer blends: an experimental and theoretical study

    NARCIS (Netherlands)

    Michels, J.J.; Breemen, A.J.J.M. van; Usman, K.; Gelinck, G.H.

    2011-01-01

    This article describes a combined experimental and theoretical study on nanophase structure development as a result of liquid phase demixing in solution-cast blends of the organic semiconductor poly(9,9'-dioctyl fluorene) (PFO) and the ferroelectric polymer poly(vinylidene fluoride-co-trifluoroethyl

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

    Energy Technology Data Exchange (ETDEWEB)

    1991-02-02

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

  10. Cu-Sn transient liquid phase wafer bonding for MEMS applications

    NARCIS (Netherlands)

    Flötgen, C.; Pawlak, M.; Pabo, E.; Wiel, H.J. van de; Hayes, G.R.; Dragoi, V.

    2013-01-01

    The impact of process parameters on final bonding layer quality was investigated for Transient Liquid Phase (TLP) wafer-level bonding based on the Cu-Sn system. Subjects of this investigation were bonding temperature profile, bonding time and contact pressure as well as the choice of metal

  11. 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

  12. 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...

  13. 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

  14. Liquid-phase reforming and hydrodeoxygenation as a two-step route to aromatics from lignin

    NARCIS (Netherlands)

    Jongerius, A.L.; Bruijnincx, P.C.A.; Weckhuysen, B.M.

    2013-01-01

    A two-step approach to the conversion of organosolv, kraft and sugarcane bagasse lignin to monoaromatic compounds of low oxygen content is presented. The first step consists of lignin depolymerization in a liquid phase reforming (LPR) reaction over a 1 wt% Pt/γ-Al2O3 catalyst at 225 °C in alkaline

  15. An Efficient Protocol for the Liquid-Phase Synthesis of Furano- and Pyranoquinolines

    Institute of Scientific and Technical Information of China (English)

    LIN,Xu-Feng; WANG,Yan-Guang; CUI,Sun-Liang; YANG,Wei-Qiang

    2004-01-01

    @@ In recent years, the liquid-phase synthesis of small heterocyclic molecules has been a subject of intense research activity, since it represents one of the most promising ways to generate small molecular libraries in the field of combinatorial chemistry. Substituted quinolines offer a high degree of structure diversity and have proven to be very important in medicinal chemistry.

  16. Highly Selective Liquid-Phase Benzylation of Anisole with Solid-Acid Zeolite Catalysts

    DEFF Research Database (Denmark)

    Poreddy, Raju; Shunmugavel, Saravanamurugan; Riisager, Anders

    2015-01-01

    Zeolites were evaluated as solid acid catalysts for the liquid-phase benzylation of anisole with benzyl alcohol, benzyl bromide, and benzyl chloride at 80 °C. Among the examined zeolites, H-mordenite-10 (H-MOR-10) demonstrated particular high activity (>99 %) and excellent selectivity (>96...

  17. Microextraction Techniques Coupled to Liquid Chromatography with Mass Spectrometry for the Determination of Organic Micropollutants in Environmental Water Samples

    Directory of Open Access Journals (Sweden)

    Mª Esther Torres Padrón

    2014-07-01

    Full Text Available Until recently, sample preparation was carried out using traditional techniques, such as liquid–liquid extraction (LLE, that use large volumes of organic solvents. Solid-phase extraction (SPE uses much less solvent than LLE, although the volume can still be significant. These preparation methods are expensive, time-consuming and environmentally unfriendly. Recently, a great effort has been made to develop new analytical methodologies able to perform direct analyses using miniaturised equipment, thereby achieving high enrichment factors, minimising solvent consumption and reducing waste. These microextraction techniques improve the performance during sample preparation, particularly in complex water environmental samples, such as wastewaters, surface and ground waters, tap waters, sea and river waters. Liquid chromatography coupled to tandem mass spectrometry (LC/MS/MS and time-of-flight mass spectrometric (TOF/MS techniques can be used when analysing a broad range of organic micropollutants. Before separating and detecting these compounds in environmental samples, the target analytes must be extracted and pre-concentrated to make them detectable. In this work, we review the most recent applications of microextraction preparation techniques in different water environmental matrices to determine organic micropollutants: solid-phase microextraction SPME, in-tube solid-phase microextraction (IT-SPME, stir bar sorptive extraction (SBSE and liquid-phase microextraction (LPME. Several groups of compounds are considered organic micropollutants because these are being released continuously into the environment. Many of these compounds are considered emerging contaminants. These analytes are generally compounds that are not covered by the existing regulations and are now detected more frequently in different environmental compartments. Pharmaceuticals, surfactants, personal care products and other chemicals are considered micropollutants. These

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

    Science.gov (United States)

    Xu, Xinhua; Wang, Xiaogang; Wu, Meifen

    2014-01-01

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

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

    Science.gov (United States)

    Xu, Xinhua; Wang, Xiaogang; Wu, Meifen

    2014-01-01

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

  20. Dynamic headspace solid-phase microextraction combined with one-dimensional gas chromatography-mass spectrometry as a powerful tool to differentiate banana cultivars based on their volatile metabolite profile.

    Science.gov (United States)

    Pontes, Marisela; Pereira, Jorge; Câmara, José S

    2012-10-15

    In this study the effect of the cultivar on the volatile profile of five different banana varieties was evaluated and determined by dynamic headspace solid-phase microextraction (dHS-SPME) combined with one-dimensional gas chromatography-mass spectrometry (1D-GC-qMS). This approach allowed the definition of a volatile metabolite profile to each banana variety and can be used as pertinent criteria of differentiation. The investigated banana varieties (Dwarf Cavendish, Prata, Maçã, Ouro and Platano) have certified botanical origin and belong to the Musaceae family, the most common genomic group cultivated in Madeira Island (Portugal). The influence of dHS-SPME experimental factors, namely, fibre coating, extraction time and extraction temperature, on the equilibrium headspace analysis was investigated and optimised using univariate optimisation design. A total of 68 volatile organic metabolites (VOMs) were tentatively identified and used to profile the volatile composition in different banana cultivars, thus emphasising the sensitivity and applicability of SPME for establishment of the volatile metabolomic pattern of plant secondary metabolites. Ethyl esters were found to comprise the largest chemical class accounting 80.9%, 86.5%, 51.2%, 90.1% and 6.1% of total peak area for Dwarf Cavendish, Prata, Ouro, Maçã and Platano volatile fraction, respectively. Gas chromatographic peak areas were submitted to multivariate statistical analysis (principal component and stepwise linear discriminant analysis) in order to visualise clusters within samples and to detect the volatile metabolites able to differentiate banana cultivars. The application of the multivariate analysis on the VOMs data set resulted in predictive abilities of 90% as evaluated by the cross-validation procedure.

  1. Comparison of ultrasound-assisted cloud point extraction and ultrasound-assisted dispersive liquid liquid microextraction for copper coupled with spectrophotometric determination.

    Science.gov (United States)

    Yang, Shengchun; Fang, Xiang; Duan, Liju; Yang, Shu; Lei, Zirong; Wen, Xiaodong

    2015-09-01

    In this work, ultrasound-assisted cloud point extraction (UA-CPE) and ultrasound-assisted dispersive liquid liquid microextraction (UA-DLLME) were investigated and compared firstly as ultrasound-assisted liquid phase microextraction methods, which were coupled with spectrophotometer for copper preconcentration and detection. Compared to conventional CPE and DLLME, the extraction patterns were changed and improved by the effect of ultrasound. As novel methods, their applications were expanded and the analytical performance of spectrophotometric determination for copper was considerably improved. The influence factors of UA-CPE and UA-DLLME were studied in detail. Under the optimal conditions, the limits of detection (LODs) for copper were 0.7 μg L(-1) of UA-CPE and 0.8 μg L(-1) of UA-DLLME with sensitivity enhancement factors (EFs) of 17 and 16. The developed methods were applied to the determination of trace copper in real water samples with satisfactory analytical results.

  2. Comparison of ultrasound-assisted cloud point extraction and ultrasound-assisted dispersive liquid liquid microextraction for copper coupled with spectrophotometric determination

    Science.gov (United States)

    Yang, Shengchun; Fang, Xiang; Duan, Liju; Yang, Shu; Lei, Zirong; Wen, Xiaodong

    2015-09-01

    In this work, ultrasound-assisted cloud point extraction (UA-CPE) and ultrasound-assisted dispersive liquid liquid microextraction (UA-DLLME) were investigated and compared firstly as ultrasound-assisted liquid phase microextraction methods, which were coupled with spectrophotometer for copper preconcentration and detection. Compared to conventional CPE and DLLME, the extraction patterns were changed and improved by the effect of ultrasound. As novel methods, their applications were expanded and the analytical performance of spectrophotometric determination for copper was considerably improved. The influence factors of UA-CPE and UA-DLLME were studied in detail. Under the optimal conditions, the limits of detection (LODs) for copper were 0.7 μg L-1 of UA-CPE and 0.8 μg L-1 of UA-DLLME with sensitivity enhancement factors (EFs) of 17 and 16. The developed methods were applied to the determination of trace copper in real water samples with satisfactory analytical results.

  3. Vapor-liquid Phase Equilibria for CO2+Tertpentanol Binary System at Elevated Pressures

    Institute of Scientific and Technical Information of China (English)

    WANG Lin; LUO Jian-cheng; YANG Hao; CHEN Kai-xun

    2011-01-01

    Vapor-liquid phase equilibrium data of tertpentanol in carbon dioxide were measured at temperatures of 313.4,323.4,333.5 and 343.5 K and in the pressure range of 4.56-11.44 MPa.The phase equilibium apparatus used in the work was a variable-volume high-pressure cell.The experimental data were reasonably correlated with Peng-Robinson equation of state(PR-EOS) together with van der Waals-2 two-parameter mixing rules.Henry's Law constants and partial molar volumes of CO2 at infinite dilution were estimated with Krichevsky-Kasarnovsky equation,and Henry's Law constants increase with increasing temperature,however,partial molar volumes of CO2 at infinite dilution are negative whose magnitudes decrease with temperature.Partial molar volumes of CO2 and tertpentanol in liquid phase at equilibrium were calculated.

  4. 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.

  5. 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.

  6. 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.

  7. Progress in the research and development of p-xylene liquid phase oxidation process

    Institute of Scientific and Technical Information of China (English)

    WANG Lijun; CHENG Youwei; WANG Qinbo; LI Xi

    2007-01-01

    The process of p-xylene liquid phase oxidation to produce purified terephthalic acid (PTA) involves a series of liquid phase radical reactions,chemical absorption,reactive crystallization,and evaporation.A commercial PTA production flow sheet includes a number of unit operations,which construct a complex process system.In this paper,a review of research and development (R & D) works on PTA process carried out in Zhejiang University during recent years is introduced.The works cover the oxidation and crystallization kinetics,gas-liquid mass transfer and evaporation,reactor modeling,database development,novel reactor design,process modeling,simulation,and optimization.The author emphasizes the viewpoint through this case study that chemical reaction engineering should be developed to process system engineering to extend its scope,and particular attention should be paid on reactor and process modeling.

  8. To the electrostrictive mechanism of nanosecond-pulsed breakdown in liquid phase

    CERN Document Server

    Seepersad, Yohan; Pekker, Mikhail; Shneider, Mikhail N; Fridman, Alexander

    2013-01-01

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

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

    CERN Document Server

    Wang, Lei

    2014-01-01

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

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

    Science.gov (United States)

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

    2014-10-01

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

  11. Stability and kinetic studies of supported ionic liquid phase catalysts for hydroformylation of propene

    DEFF Research Database (Denmark)

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

    2005-01-01

    Supported ionic liquid phase (SILP) catalysts have been studied with regard to their long-term stability in the continuous gas-phase hydroformylation of propene. Kinetic data have been acquired by variation of temperature, pressure, syngas composition, substrate concentration, and residence time...... exceeded 200 h time on stream with no loss in selectivity. A small decrease in activity could be compensated by a vacuum procedure regaining the initial activity....

  12. Reduced free carrier absorption loss in midinfrared double heterostructure diode lasers grown by liquid phase epitaxy. .

    OpenAIRE

    Yin, M; Krier, A.; Jones, Robert; Carrington, Peter

    2007-01-01

    An improved InAsSb/InAsSbP double heterojunction ridge laser was designed and grown by liquid phase epitaxy. The cladding layer absorption loss was minimized by the introduction of two undoped quaternary layers on either side of the active region to form a five layer epitaxial structure. The inserted layers also helped alleviate interdiffusion of unwanted dopants into the active region and reduced current leakage in the device. The resulting diode lasers operate readily in pulsed mode near 3....

  13. The liquid phase oxidation of n-butane: a search for plausible mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, C.C. [Celanese Ltd., TX (United States). Corpus Christi Technical Center

    1998-12-31

    This articles deals with an approach that has given some key information about the mechanisms of the liquid phase oxidation of butane to acetic acid. This procedure has been developed over the last 34 years; however, much of what will be discussed represents a synthesis of previous insights. Many of the observations are relatively recent and have not been previously published. In principle, this approach should be applicable to many oxidation processes. (orig.)

  14. Kinetic Study on Liquid-Phase Hydrodesulfurization of FCC Diesel in Tubular Reactors

    Institute of Scientific and Technical Information of China (English)

    Li Hua; Yang Jinliang; Weng Huixin; Wang Jiming

    2015-01-01

    According to the characteristics of FCC diesel, a technology of liquid-phase hydrodesulfurization of the diesel in tubular reactors was proposed and lab-scale experiments were carried out. A kinetic model for the hydrodesulfurization pro-cess was developed and veriifed. The model was utilized to predict the sulfur content of products under different operating conditions. The effects of temperature, space velocity, pressure, and hydrogen concentration on the desulfurization rate were investigated.

  15. 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.

  16. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Preidel, V., E-mail: veit.preidel@helmholtz-berlin.de; Amkreutz, D.; Haschke, J.; Wollgarten, M.; Rech, B.; Becker, C. [Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Division Renewable Energy, Kekuléstr. 5, 12489 Berlin (Germany)

    2015-06-14

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

  18. Computer simulation of free settling and skeletal settling during liquid phase sintering

    Directory of Open Access Journals (Sweden)

    Nikolić Z.S.

    2006-01-01

    Full Text Available In recent years, a range of computer simulation models leading to a better understanding of liquid phase sintering phenomena, have been developed with the aim of simulating the detailed evolution of microstructure during grain growth. Some liquid phase sintered materials show both macrostructural and microstructural effects associated with gravity force. Therefore we will develop a numerical procedure for the estimation of how much gravity will influence domain (two-dimensional particle representation growth, domain boundary migration and solid skeleton formation due to gravity induced segregation during liquid phase sintering. The method used for the simulation of a gravity field will be based on the settling procedure. Gravity induced settling will be separated into two stages - Free Settling and Skeletal Settling. Isolated solid phase domains fall under gravity and slide down over the already settled domains (free settling. During settling they make point contacts with each other. Necks between them then form and start to grow until the equilibrium dihedral angle between the domain boundaries and the liquid is established. Thus a solid skeleton forms and skeletal settling of a connected solid structure takes place. .

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

    Energy Technology Data Exchange (ETDEWEB)

    None

    1997-09-30

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

  20. Two-liquid phase partitioning biotrickling filters for methane abatement: exploring the potential of hydrophobic methanotrophs.

    Science.gov (United States)

    Lebrero, Raquel; Hernández, Laura; Pérez, Rebeca; Estrada, José M; Muñoz, Raúl

    2015-03-15

    The potential of two-liquid phase biotrickling filters (BTFs) to overcome mass transfer limitations derived from the poor aqueous solubility of CH4 has been scarcely investigated to date. In this context, the abatement of diluted methane emissions in two-liquid phase BTFs was evaluated using two different inocula: a type II methanotrophs culture in BTF 1 and a hydrophobic microbial consortium capable of growing inside silicone oil in BTF 2. Both BTFs supported stable elimination capacities above 45 g m(-3) h(-1) regardless of the inoculum, whereas no improvement derived from the presence of hydrophobic microorganisms compared to the type II metanotrophs culture was observed. Interestingly, the addition of silicone oil mediated a reduced metabolites concentration in the recycling aqueous phase, thus decreasing the needs for mineral medium renewal. Moreover, a 78% similarity was recorded between the microbial communities enriched in both BTFs at the end of the experimental period in spite of the differences in the initial inoculum structure. The results obtained confirmed the superior performance of two-liquid phase BTFs for CH4 abatement compared with conventional biotrickling filters.

  1. The recent developments in dispersive liquid–liquid microextraction for preconcentration and determination of inorganic analytes

    Directory of Open Access Journals (Sweden)

    H.M. Al-Saidi

    2014-12-01

    Full Text Available Recently, increasing interest on the use of dispersive liquid–liquid microextraction (DLLME developed in 2006 by Rezaee has been found in the field of separation science. DLLME is miniaturized format of liquid–liquid extraction in which acceptor-to-donor phase ratio is greatly reduced compared with other methods. In the present review, the combination of DLLME with different analytical techniques such as atomic absorption spectrometry (AAS, inductively coupled plasma-optical emission spectrometry (ICP-OES, gas chromatography (GC, and high-performance liquid chromatography (HPLC for preconcentration and determination of inorganic analytes in different types of samples will be discussed. Recent developments in DLLME, e.g., displacement-DLLME, the use of an auxiliary solvent for adjustment of density of extraction mixture, and the application of ionic liquid-based DLLME in determination of inorganic species even in the presence of high content of salts are presented in the present review. Finally, comparison of DLLME with the other liquid-phase microextraction approaches and limitations of this technique are provided.

  2. Speciation analysis of aqueous nanoparticulate diclofenac complexes by solid-phase microextraction

    NARCIS (Netherlands)

    Zielinska, K.; Leeuwen, van H.P.; Thibault, S.; Town, R.M.

    2012-01-01

    The dynamic sorption of an organic compound by nanoparticles (NPs) is analyzed by solid-phase microextraction (SPME) for the example case of the pharmaceutical diclofenac in dispersions of impermeable (silica, SiO(2)) and permeable (bovine serum albumin, BSA) NPs. It is shown that only the protonate

  3. A microstructure-based model for shape distortion during liquid phase sintering

    Science.gov (United States)

    Upadhyaya, Anish

    Tight dimensional control is a major concern in consolidation of alloys via liquid phase sintering. This research demonstrates the role of microstructure in controlling the bulk dimensional changes that occur during liquid phase sintering. The dimensional changes were measured using a coordinate measuring machine and also on a real-time basis using in situ video imaging. To quantify compact distortion, a distortion parameter is formulated which takes into consideration the compact distortion in radial as well as axial directions. The microstructural attributes considered in this study are as follows: solid content, dihedral angle, grain size, grain contiguity and connectivity, and solid-solubility. Sintering experiments were conducted with the W-Ni-Cu, W-Ni-Fe, Mo-Ni-Cu, and Fe-Cu systems. The alloy systems and the compositions were selected to give a range of microstructures during liquid phase sintering. The results show that distortion correlates with the measured microstructural attributes. Systems containing a high solid content, high grain coordination number and contiguity, and large dihedral angle have more structural rigidity. The results show that a minimum two-dimensional grain coordination number of 3.0 is necessary for shape preservation. Based on the experimental observations, a model is derived that relates the critical solid content required for maintaining structural rigidity to the dihedral angle. The critical solid content decreases with an increasing dihedral angle. Consequently, W-Cu alloys, which have a dihedral angle of about 95sp°, can be consolidated without gross distortion with as little as 20 vol.% solid. To comprehensively understand the gravitational effects in the evolution of both the microstructure and the macrostructure during liquid phase sintering, W-Ni-Fe alloys with W content varying from 78 to 93 wt.% were sintered in microgravity. Compositions that slump during ground-based sintering also distort when sintered under

  4. Liquid-Phase Exfoliation of Graphite into Single- and Few-Layer Graphene with α-Functionalized Alkanes.

    Science.gov (United States)

    Haar, Sébastien; Bruna, Matteo; Lian, Jian Xiang; Tomarchio, Flavia; Olivier, Yoann; Mazzaro, Raffaello; Morandi, Vittorio; Moran, Joseph; Ferrari, Andrea C; Beljonne, David; Ciesielski, Artur; Samorì, Paolo

    2016-07-21

    Graphene has unique physical and chemical properties, making it appealing for a number of applications in optoelectronics, sensing, photonics, composites, and smart coatings, just to cite a few. These require the development of production processes that are inexpensive and up-scalable. These criteria are met in liquid-phase exfoliation (LPE), a technique that can be enhanced when specific organic molecules are used. Here we report the exfoliation of graphite in N-methyl-2-pyrrolidinone, in the presence of heneicosane linear alkanes terminated with different head groups. These molecules act as stabilizing agents during exfoliation. The efficiency of the exfoliation in terms of the concentration of exfoliated single- and few-layer graphene flakes depends on the functional head group determining the strength of the molecular dimerization through dipole-dipole interactions. A thermodynamic analysis is carried out to interpret the impact of the termination group of the alkyl chain on the exfoliation yield. This combines molecular dynamics and molecular mechanics to rationalize the role of functionalized alkanes in the dispersion and stabilization process, which is ultimately attributed to a synergistic effect of the interactions between the molecules, graphene, and the solvent.

  5. Growth of high purity semiconductor epitaxial layers by liquid phase epitaxy and their characterization

    Indian Academy of Sciences (India)

    S Dhar

    2005-07-01

    This paper briefly describes our work and the results on the growth of several III–V epitaxial semiconductor materials in high purity form by liquid phase epitaxy (LPE) technique. Various possible sources of impurities in such growth are listed and step-by-step procedures adopted to reduce them are discussed in particular reference to the growth of GaAs layers. The technique of growing very high purity layers by treating the melt with erbium is described for the growth of InGaAs and GaSb layers.

  6. Numerical simulation on influence of bonding temperature in transient liquid phase bonding

    Science.gov (United States)

    Hynes, N. Rajesh Jesudoss; Raja, M. Karthick

    2016-05-01

    In this article, numerical simulation of transient liquid phase bonding of ceramic/metal joint has been carried out by using Finite Element Analysis (FEA) software. To increase the wettability, aluminium sheet was used as an interlayer. Hence, numerical simulation of TLP bonding process is done by varying the bonding temperature. Transient thermal analysis had been carried out for each cases and temperature distribution was predicted by the developed numerical model. From the simulation studies, it is found that the decrease in bonding temperature enhances favourable temperature distribution and eventually improves the joint efficiency of graphite/copper joints.

  7. Moessbauer characterization of joints of steel pieces in transient liquid phase bonding experiences

    Energy Technology Data Exchange (ETDEWEB)

    Di Luozzo, N.; Martinez Stenger, P. F.; Canal, J. P.; Fontana, M. R.; Arcondo, B., E-mail: barcond@fi.uba.ar [INTECIN (UBA-CONICET), Laboratorio de Solidos Amorfos, Facultad de Ingenieria (Argentina)

    2011-11-15

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

  8. Enhanced Corrosion Resistance of a Transient Liquid Phase Bonded Nickel-Based Superalloy

    Science.gov (United States)

    Adebajo, O. J.; Ojo, O. A.

    2017-01-01

    Electrochemical analysis of corrosion performance of a transient liquid phase (TLP) bonded nickel-based superalloy was performed. The TLP bonding process resulted in significant reduction in corrosion resistance due to the formation of non-equilibrium solidification reaction micro-constituents within the joint region. The corrosion resistance degradation is completely eliminated through a new application of composite interlayer that had been previously considered unusable for joining single-crystal superalloys. The effectiveness of the new approach becomes more pronounced as the severity of environment increases.

  9. Joining of Ion Transport Membranes Using a Novel Transient Liquid Phase Process

    Energy Technology Data Exchange (ETDEWEB)

    Darryl P. Butt

    2006-08-30

    The feasibility of a novel transient liquid phase (TLP) joining method has been demonstrated in joining La{sub 0.9}Ca{sub 0.1}FeO{sub 3} materials. Metal oxide powders were processed to form the TLP compositions which were used in the joining process. The method has been successful in producing joint interfaces that effectively disappear, as they are the same material and have the same properties as the joined parts. The feasibility of the method has been demonstrated for a single system, but many systems where the method can potentially be applied have been identified.

  10. Foaming and rheological properties of the liquid phase extracted from wheat flour dough

    OpenAIRE

    2015-01-01

    Dough liquor (DL) is considered as a good model of bread dough liquid phase which plays an important role in alveolar structure creation. In this work, DL was extracted from dough pieces of various contents (g for 100 g flour) of water (55-70), sugar (0-15), rapeseed oil (0-10) and bran (0-20). The extraction yield of DL was 5.0 +/- 2.4% and its dry matter content varied between 10.8 and 27.2% of total DL mass. Its composition has been determined in terms of lipids content (

  11. Solid-liquid phase equilibria of Fe-Cr-Al alloys and spinels

    Science.gov (United States)

    McMurray, J. W.; Hu, R.; Ushakov, S. V.; Shin, D.; Pint, B. A.; Terrani, K. A.; Navrotsky, A.

    2017-08-01

    Ferritic FeCrAl alloys are candidate accident tolerant cladding materials. There is a paucity of data concerning the melting behavior for FeCrAl and its oxides. Analysis tools have therefore had to utilize assumptions for simulations using FeCrAl cladding. The focus of this study is to examine in some detail the solid-liquid phase equilibria of FeCrAl alloys and spinels with the aim of improving the accuracy of severe accident scenario computational studies.

  12. 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.

  13. Biopolymer-supported ionic-liquid-phase ruthenium catalysts for olefin metathesis.

    Science.gov (United States)

    Clousier, Nathalie; Filippi, Alexandra; Borré, Etienne; Guibal, Eric; Crévisy, Christophe; Caijo, Fréderic; Mauduit, Marc; Dez, Isabelle; Gaumont, Annie-Claude

    2014-04-01

    Original ruthenium supported ionic liquid phase (SILP) catalysts based on alginates as supports were developed for olefin metathesis reactions. The marine biopolymer, which fulfills most of the requisite properties for a support such as widespread abundance, insolubility in the majority of organic solvents, a high affinity for ionic liquids, high chemical stability, biodegradability, low cost, and easy processing, was impregnated by [bmim][PF6 ] containing an ionically tagged ruthenium catalyst. These biosourced catalysts show promising performances in ring-closing metathesis (RCM) and cross-metathesis (CM) reactions, with a high level of recyclability and reusability combined with a good reactivity.

  14. Liquid Phase Sintering (LPS) and Dielectric Constant of α-Silicon Nitride Ceramic

    Institute of Scientific and Technical Information of China (English)

    CHEN Changlian; CHEN Fei; SHEN Qiang; ZHANG Lianmeng; YAN Faqiang

    2006-01-01

    The spark plasma sintering (SPS) was applied to prepare α-Si3N4 ceramics of different densities with magnesia, silicon dioxide, alumina as the sintering aids. The mechanism of liquid phase sintering (LPS) was discussed and the factors influencing the density of the prepared samples were analyzed. The dielectric constant of sintered samples was tested. The experimental results show that the density can be controlled from 2.48 g/cm3 to 3.09 g/cm3 while the content of the sintering aids and the sintering temperature alter and the dielectric constant is closely dependent on the density of obtained samples.

  15. Multistep liquid-phase lithography for fast prototyping of microfluidic free-flow-electrophoresis chips.

    Science.gov (United States)

    Jezierski, Stefan; Gitlin, Leonid; Nagl, Stefan; Belder, Detlev

    2011-11-01

    We present a fast and versatile method to produce functional micro free-flow electrophoresis chips. Microfluidic structures were generated between two glass slides applying multistep liquid-phase lithography, omitting troublesome bonding steps or cost-intensive master structures. Utilizing a novel spacer-less approach with the photodefinable polymer polyethyleneglycol dimethacrylate (PEG-DA), microfluidic devices with hydrophilic channels of only 25 μm in height were generated. The microfluidic chips feature ion-permeable segregation walls between the electrode channels and the separation bed and hydrophilic surfaces. The performance of the chip is demonstrated by free-flow electrophoretic separation of fluorescent xanthene dyes and fluorescently labeled amino acids.

  16. 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.

  17. A Novel Catalyst for Liquid Phase Hydrogenation of m-Dinitrobenzene to m-Phenylenediamine

    Institute of Scientific and Technical Information of China (English)

    Ying Xin LIU; Zuo Jun WEI; Ji Xiang CHEN; Ji Yan ZHANG; Xin Xue LI; Xiong Hui WEI

    2005-01-01

    A novel lanthana-promoted nickel catalyst supported on silica for the liquid phase hydrogenation of m-dinitrobenzene to m-phenylenediamine was prepared by an incipient wetness sequential impregnation method. It was found that Ni-La/SiO2 catalyst exhibited high activity and stability for m-dinitrobenzene hydrogenation. Over this catalyst, the conversion of m-dinitrobenzene and the yield of m-phenylenediamine were up to 97.1% and 93.5%, respectively,at 373 K and 2.6 MPa hydrogen pressure after reaction for 1 h.

  18. Organic molecules modified palladium nanowires arrays prepared by high temperature liquid phase reduction

    Institute of Scientific and Technical Information of China (English)

    Shen Cheng-Min; Yang Tian-Zhong; Xiao Cong-Wen; Zhang Huai-Ruo; Tian Ji-Fa; Bao Li-Hong; Li Chen; Li Jian-Qi; Gao Hong-Jun

    2008-01-01

    This paper reports high temperature liquid phase synthesis of Pd nanowires using chemically modified porous anodic aluminium oxide as template. In this synthesis process, oleic acid is used to modify the inner wall of the pores and Pd2+ complex with oleylamine is filled into the channel of the template. The complex is then reduced to give oleylamine-capped Pd nanowires. This paper suggests that oleic acid can improve the environment of inner wall of the pores, leading to the formation of uniform Pd nanowires. The synthetic process can be extended to make other types of nanowires.

  19. Poly(ethylene glycol)-supported Liquid-phase Parallel Synthesis of Di(aryloxyacetyl)thiosemicarbazides

    Institute of Scientific and Technical Information of China (English)

    Xi Cun WANG; Jun Ke WANG; Zheng LI

    2004-01-01

    An efficient poly(ethylene glycol) (PEG)-supported liquid-phase parallel approach to di(aryloxyacetyl)thiosemicarbazides is described. PEG-bound phenol reacted with chloroacetic acid to afford PEG-bound phenyloxyacetic acid, which was readily converted into corresponding phenyloxyacetyl chloride. Subsequent nucleophilic substitution with ammonium thiocyanate followed by addition of aryloxyacetic acid hydrazides gave PEG-bound di(aryloxyacetyl)thiosemi- carbazides, which were easily cleaved to give the resulting library of 1-aryloxyacetyl-4-(4'- methoxylcarbonylphenyloxyacetyl)thiosemicarbazides in good to high yield and high purity.

  20. 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...

  1. Development of headspace solid-phase microextraction method for ...

    African Journals Online (AJOL)

    ... solid-phase microextraction method for the analysis of pesticide residues in fruit and ... Journal of Applied Sciences and Environmental Management ... interface temperature) and solid phase microextraction parameters (fiber coating type, ...

  2. 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.

  3. 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.

  4. The Promotion of Liquid Phase Sintering of Boron-Containing Powder Metallurgy Steels by Adding Nickel

    Directory of Open Access Journals (Sweden)

    Wu Ming-Wei

    2015-01-01

    Full Text Available Boron is a feasible alloying element for liquid phase sintering (LPS of powder metallurgy (PM steels. This study investigated the effect of nickel (Ni, which is widely used in PM steels, on the liquid phase sintering of boron-containing PM steels. The results showed that the addition of 1.8wt% Ni does not apparently modify the LPS mechanism of boron-containing PM steels. However, adding 1.8wt% Ni slightly improves the LPS densification from 0.60 g/cm3 to 0.65 g/cm3, though the green density is reduced. Thermodynamic simulation demonstrated that the presence of Ni lowers the temperature region of liquid formation, resulting in enhanced LPS densification. Moreover, original graphite powders remains in the steels sintered at 1200 ºC. These graphite powders mostly dissolve into the base iron powder when the sintering temperature is increased from 1200 ºC to 1250 ºC.

  5. Liquid phase crystallized silicon on glass: Technology, material quality and back contacted heterojunction solar cells

    Science.gov (United States)

    Haschke, Jan; Amkreutz, Daniel; Rech, Bernd

    2016-04-01

    Liquid phase crystallization has emerged as a novel approach to grow large grained polycrystalline silicon films on glass with high electronic quality. In recent years a lot of effort was conducted by different groups to determine and optimize suitable interlayer materials, enhance the crystallographic quality or to improve post crystallization treatments. In this paper, we give an overview on liquid phase crystallization and describe the necessary process steps and discuss their influence on the absorber properties. Available line sources are compared and different interlayer configurations are presented. Furthermore, we present one-dimensional numerical simulations of a rear junction device, considering silicon absorber thicknesses between 1 and 500 µm. We vary the front surface recombination velocity as well as doping density and minority carrier lifetime in the absorber. The simulations suggest that a higher absorber doping density is beneficial for layer thicknesses below 20 µm or when the minority carrier lifetime is short. Finally, we discuss possible routes for device optimization and propose a hybride cell structure to circumvent current limitations in device design.

  6. Vapour-liquid phase diagram for an ionic fluid in a random porous medium.

    Science.gov (United States)

    Holovko, M F; Patsahan, O; Patsahan, T

    2016-10-19

    We study the vapour-liquid phase behaviour of an ionic fluid confined in a random porous matrix formed by uncharged hard sphere particles. The ionic fluid is modelled as an equimolar binary mixture of oppositely charged equisized hard spheres, the so-called restricted primitive model (RPM). Considering the matrix-fluid system as a partly-quenched model, we develop a theoretical approach which combines the method of collective variables with the extension of the scaled-particle theory (SPT) for a hard-sphere fluid confined in a disordered hard-sphere matrix. The approach allows us to formulate the perturbation theory using the SPT for the description of the thermodynamics of the reference system. The phase diagrams of the RPM in matrices of different porosities and for different size ratios of matrix and fluid particles are calculated in the random-phase approximation and also when the effects of higher-order correlations between ions are taken into account. Both approximations correctly reproduce the basic effects of porous media on the vapour-liquid phase diagram, i.e. with a decrease of porosity the critical point shifts towards lower fluid densities and lower temperatures and the coexistence region gets narrower. For the fixed matrix porosity, both the critical temperature and the critical density increase with an increase of size of matrix particles and tend to the critical values of the bulk RPM.

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

    Science.gov (United States)

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

    1978-01-01

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

  8. A study on the two-step transient liquid phase diffusion bonding of K640 superalloy

    Institute of Scientific and Technical Information of China (English)

    Zhang Lei; Hou Jinbao; Zhang Sheng

    2007-01-01

    A new technology, the two-step transient liquid phase diffusion bonding (TLP-DB) technology for cobalt-based K640 superalloy, was investigated. The method consists of a short-time high temperature heating to melt interlayer followed by isothermal solidification of liquid phase at a lower temperature than that of the conventional TLP-DB. The result indicates that the two-step TLP-DB can reliably produce an ideal joint with uniform chemical composition, which is superior to the joint welded by conventional TLP-DB in microstructure and mechanical properties. Bonding parameters of new process are 1 250 ℃ for 0.5 h and 1 180 ℃ for 3 h. The high-temperature tensile strength of the joint by two-step TLP-DB reaches 74% of that of the base material on an equal basis, but the high-temperature tensile strength of the joint by conventional TLP-DB is only 58% of that of the base material.

  9. Microstructure Evolution and Mechanical Properties Improvement in Liquid-Phase-Sintered Hydroxyapatite by Laser Sintering.

    Science.gov (United States)

    Duan, Songlin; Feng, Pei; Gao, Chengde; Xiao, Tao; Yu, Kun; Shuai, Cijun; Peng, Shuping

    2015-03-17

    CaO-Al₂O₃-SiO₂ (CAS) as a liquid phase was introduced into hydroxyapatite (HAp) to prepare bone scaffolds. The effects of the CAS content (1, 2, 3, 4 and 5 wt%) on microstructure and mechanical properties of HAp ceramics were investigated. The optimal compression strength, fracture toughness and Vickers hardness reached 22.22 MPa, 1.68 MPa·m(1/2) and 4.47 GPa when 3 wt% CAS was added, which were increased by 105%, 63% and 11% compared with those of HAp ceramics without CAS, respectively. The improvement of the mechanical properties was attributed to the improved densification, which was caused by the solid particle to rearrange during liquid phase sintering. Moreover, simulated body fluid (SBF) study indicated the HAp ceramics could maintain the mechanical properties and form a bone-like apatite layer when they were immersed in SBF. Cell culture was used to evaluate biocompatibility of the HAp ceramics. The results demonstrated MG-63 cells adhered and spread well.

  10. Partition Behavior of Penicillin in Three-liquid-phase Extraction System

    Institute of Scientific and Technical Information of China (English)

    谭显东; 季清荣; 常志东

    2006-01-01

    Partition behavior of penicillins G and V was studied in a novel three-liquid-phase extraction system, which is composed of butyl acetate (BA), polyethylene glycol (PEG), ammonia sulfate [(NH4)2SO4] and water (H2O). The main components in the top, middle and bottom phases are butyl acetate, polyethylene glycol aqueous solution and ammonia sulfate aqueous solution, respectively. Some parameters such as partition coefficients Di/j and mass fractions Ei ofpenicillins G and V were determined at the room temperature, respectively. Experimental efforts have been made to investigate the partition behavior of penicillin in the three-liquid-phase extraction system, including initial concentrations of phase-forming components [PEG and (NH4)2SO4], PEG molecular weight, pH, initial concentration of penicillin. The results indicated that penicillins G and V have the similar partition behavior. They preferentially distribute into the middle phase with the increase of initial concentration of phase-forming components and into the top phase with the decrease of pH, while partition coefficient Dm/b is hardly affected by pH value. The variation of PEG molecular weight has little effect on mass fractions of penicillin. The increase of initial concentration of penicillins G and V could lead to the increase of Dt/b, Dm/b and the decrease of Dt/m, while their mass fractions in all phases were almost independent on their initial concentrations.

  11. Vapour-liquid phase diagram for an ionic fluid in a random porous medium

    Science.gov (United States)

    Holovko, M. F.; Patsahan, O.; Patsahan, T.

    2016-10-01

    We study the vapour-liquid phase behaviour of an ionic fluid confined in a random porous matrix formed by uncharged hard sphere particles. The ionic fluid is modelled as an equimolar binary mixture of oppositely charged equisized hard spheres, the so-called restricted primitive model (RPM). Considering the matrix-fluid system as a partly-quenched model, we develop a theoretical approach which combines the method of collective variables with the extension of the scaled-particle theory (SPT) for a hard-sphere fluid confined in a disordered hard-sphere matrix. The approach allows us to formulate the perturbation theory using the SPT for the description of the thermodynamics of the reference system. The phase diagrams of the RPM in matrices of different porosities and for different size ratios of matrix and fluid particles are calculated in the random-phase approximation and also when the effects of higher-order correlations between ions are taken into account. Both approximations correctly reproduce the basic effects of porous media on the vapour-liquid phase diagram, i.e. with a decrease of porosity the critical point shifts towards lower fluid densities and lower temperatures and the coexistence region gets narrower. For the fixed matrix porosity, both the critical temperature and the critical density increase with an increase of size of matrix particles and tend to the critical values of the bulk RPM.

  12. Microstructure Evolution and Mechanical Properties Improvement in Liquid-Phase-Sintered Hydroxyapatite by Laser Sintering

    Directory of Open Access Journals (Sweden)

    Songlin Duan

    2015-03-01

    Full Text Available CaO-Al2O3-SiO2 (CAS as a liquid phase was introduced into hydroxyapatite (HAp to prepare bone scaffolds. The effects of the CAS content (1, 2, 3, 4 and 5 wt% on microstructure and mechanical properties of HAp ceramics were investigated. The optimal compression strength, fracture toughness and Vickers hardness reached 22.22 MPa, 1.68 MPa·m1/2 and 4.47 GPa when 3 wt% CAS was added, which were increased by 105%, 63% and 11% compared with those of HAp ceramics without CAS, respectively. The improvement of the mechanical properties was attributed to the improved densification, which was caused by the solid particle to rearrange during liquid phase sintering. Moreover, simulated body fluid (SBF study indicated the HAp ceramics could maintain the mechanical properties and form a bone-like apatite layer when they were immersed in SBF. Cell culture was used to evaluate biocompatibility of the HAp ceramics. The results demonstrated MG-63 cells adhered and spread well.

  13. Monosaccharide composition analysis of immunomodulatory polysaccharides by on-line hollow fiber microextraction with high-performance liquid chromatography.

    Science.gov (United States)

    Wang, Nani; Wang, Xuping; Huang, Xiaowen; Mao, Zhujun; Zhang, Yang; Yu, Yong; Shou, Dan

    2016-03-01

    The monosaccharide compositions of functional polysaccharides are essential for structure elucidation and biological activity determination. A sensitive method based on on-line hollow-fiber liquid-phase microextraction with high-performance liquid chromatography has been established for the analysis of ten monosaccharide compositions (two uronic acids, two amino sugars and six neutral sugars) of the immunomodulatory polysaccharides. After derivatization, the sample was injected into the lumen of a hollow fiber immersed in butyl ether and separated by liquid chromatography. Under optimized conditions, the calibration curves were linear (r ≥ 0.9996) in the range of 10-2000 μmol L(-1) . The limits of detection were in the range of 0.04-1.58 μmol L(-1) , and the recoveries were in the range of 92.1-99.6%, which shows that the method is applicable to the analysis of the monosaccharide composition of various polysaccharides.

  14. Design and implementation of an automated liquid-phase microextraction-chip system coupled on-line with high performance liquid chromatography

    DEFF Research Database (Denmark)

    Li, Bin; Petersen, Nickolaj J.; Payán, María D Ramos

    2014-01-01

    . The composition of the supported liquid membrane (SLM) and carrier was optimized in order to achieve reasonable extraction performance of all the five alkaloids. With 1-octanol as SLM solvent and with 25mM sodium octanoate as anionic carrier, extraction recoveries for the different opium alkaloids ranged between...... 17% and 45%. The extraction provided high selectivity, and no interfering peaks in the chromatograms were observed when applied to human urine samples spiked with alkaloids. The detection limits using UV-detection were in the range of 1-21ng/mL for the five opium alkaloids presented in water samples...

  15. Combination of electromembrane extraction and liquid-phase microextraction in a single step: Simultaneous group separation of acidic and basic drugs

    DEFF Research Database (Denmark)

    Huang, Chuixiu; Seip, Knut Fredrik; Gjelstad, Astrid

    2015-01-01

    as the SLM for LPME, basic and acidic drugs were extracted and separated simultaneously from a low pH sample by EME and LPME, respectively. After 15 min of extraction, basic drugs (citalopram and sertraline) were exhaustively extracted, whereas the recoveries for acidic drugs (ketoprofen and ibuprofen) were...

  16. Quantum Dots obtained by LPE from under-saturated In-As liquid phases on GaAs substrates

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz F E; Mishurnyi V; Gorbatchev A; De Anda F [Universidad Autonoma de San Luis Potosi, Instituto de Investigacion en Comunicacion Optica, Av. Karacorum 1470, Col. Lomas 4a Sec., CP 78210San Luis PotosI (Mexico); Prutskij T, E-mail: fcoe_ov@prodigy.net.mx, E-mail: andre@cactus.iico.uaslp.mx [BUAP, Instituto de Ciencias, Apartado Postal 207, 72000, Puebla (Mexico)

    2011-01-01

    In this work we inform about quantum dots (QD) obtained by Liquid Phase Epitaxy (LPE) on GaAs substrates from under-saturated In-As liquid phases. In our processes, we have prepared saturated In-rich liquid phases by dissolving an InAs wafer at one of the temperatures interval from 450 to 414 C for 60 minutes. The contact between In-As liquid phase and the GaAs substrate was always done at a constant temperature of 444 C for 5 seconds. Thus, the growth temperature for most of the samples was higher than the liquidus temperature. We think that the growth driving force is related to a transient process that occurs when the system is trying to reach equilibrium. Under the atom force microscope (AFM) we have observed nano-islands on the surfaces of the samples obtained from under-saturated liquid phases prepared at 438, 432 and 426 C. The 25 K photoluminescence spectrum shows a peak at a 1.33 eV, in addition to the GaAs related line.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-06-01

    This project, which was sponsored by the U.S. Department of Energy (DOE) under the Clean Coal Technology Program to demonstrate the production of methanol from coal-derived synthesis gas (syngas), has completed the 69-month operating phase of the program. The purpose of this Final Report for the ''Commercial-Scale Demonstration of the Liquid Phase Methanol (LPMEOH{trademark}) Process'' is to provide the public with details on the performance and economics of the technology. The LPMEOH{trademark} Demonstration Project was a $213.7 million cooperative agreement between the DOE and Air Products Liquid Phase Conversion Company, L.P. (the Partnership). The DOE's cost share was $92,708,370 with the remaining funds coming from the Partnership. The LPMEOH{trademark} demonstration unit is located at the Eastman Chemical Company (Eastman) chemicals-from-coal complex in Kingsport, Tennessee. The technology was the product of a cooperative development effort by Air Products and Chemicals, Inc. (Air Products) and DOE in a program that started in 1981. Developed to enhance electric power generation using integrated gasification combined cycle (IGCC) technology, the LPMEOH{trademark} Process is ideally suited for directly processing gases produced by modern coal gasifiers. Originally tested at the Alternative Fuels Development Unit (AFDU), a small, DOE-owned process development facility in LaPorte, Texas, the technology provides several improvements essential for the economic coproduction of methanol and electricity directly from gasified coal. This liquid phase process suspends fine catalyst particles in an inert liquid, forming a slurry. The slurry dissipates the heat of the chemical reaction away from the catalyst surface, protecting the catalyst, and allowing the methanol synthesis reaction to proceed at higher rates. The LPMEOH{trademark} Demonstration Project accomplished the objectives set out in the Cooperative Agreement with DOE for this Clean

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

    Science.gov (United States)

    Amos, Fairland F.

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

  19. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    None

    1998-12-21

    The Liquid Phase Methanol (LPMEOW) Demonstration Project at Kingsport, Tennessee, is a $213.7 million cooperative agreement between the U.S. Department of Energy (DOE) and Air Products Liquid Phase Conversion Company, L.P. (the Partnership) to produce methanol from coal-derived synthesis gas (syngas). Air Products and Chemicals, Inc. (Air Products) and Eastman Chemical Company (Eastman) formed the Partnership to execute the Demonstration Project. The LPMEOI-P Process Demonstration Unit was built at a site located at the Eastman coal-to-chemicals complex in Kingsport. During this quarter, initial planning and procurement work continued on the seven project sites which have been accepted for participation in the off-site, product-use test program. Approximately 12,000 gallons of fuel-grade methanol (98+ wt% methanol, 4 wt% water) produced during operation on carbon monoxide (CO)-rich syngas at the LPMEOW Demonstration Unit was loaded into trailers and shipped off-site for Mure product-use testing. At one of the projects, three buses have been tested on chemical-grade methanol and on fhel-grade methanol from the LPMEOW Demonstration Project. During the reporting period, planning for a proof-of-concept test run of the Liquid Phase Dimethyl Ether (LPDME~ Process at the Alternative Fuels Development Unit (AFDU) in LaPorte, TX continued. The commercial catalyst manufacturer (Calsicat) has prepared the first batch of dehydration catalyst in large-scale equipment. Air Products will test a sample of this material in the laboratory autoclave. Catalyst activity, as defined by the ratio of the rate constant at any point in time to the rate constant for freshly reduced catalyst (as determined in the laborato~ autoclave), was monitored for the initial extended operation at the lower initial reactor operating temperature of 235oC. At this condition, the decrease in catalyst activity with time from the period 20 December 1997 through 27 January 1998 occurred at a rate of 1.0% per

  1. Determination of atenolol in human plasma using ionic-liquid-based ultrasound-assisted in situ solvent formation microextraction followed by high-performance liquid chromatography.

    Science.gov (United States)

    Zeeb, Mohsen; Farahani, Hadi; Papan, Mohammad Kazem

    2016-06-01

    An efficient analytical method called ionic-liquid-based ultrasound-assisted in situ solvent formation microextraction followed by high-performance liquid chromatography was developed for the determination of atenolol in human plasma. A hydrophobic ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate) was formed by the addition of a hydrophilic ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate) to a sample solution containing an ion-pairing agent during microextraction. The analyte was extracted into the ionic liquid phase while the microextraction solvent was dispersed throughout the sample by utilizing ultrasound. The sample was then centrifuged, and the extracting phase retracted into the microsyringe and injected to liquid chromatography. After optimization, the calibration curve showed linearity in the range of 2-750 ng/mL with the regression coefficient corresponding to 0.998. The limits of detection (S/N = 3) and quantification (S/N = 10) were 0.5 and 2 ng/mL, respectively. A reasonable relative recovery range of 90-96.7% and satisfactory intra-assay (4.8-5.1%, n = 6) and interassay (5.0-5.6%, n = 9) precision along with a substantial sample clean-up demonstrated good performance of the procedure. It was applied for the determination of atenolol in human plasma after oral administration and some pharmacokinetic data were obtained.

  2. Room temperature ionic liquid-based microextraction for vanadium species separation and determination in water samples by electrothermal atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Berton, Paula; Martinis, Estefania M. [Laboratory of Environmental Research and Services of Mendoza (LISAMEN), (CCT-CONICET-Mendoza), Av. Ruiz Leal S/N Parque General San Martin, CC. 131, M 5502 IRA Mendoza (Argentina); Martinez, Luis D. [INQUISAL-CONICET, Departamento de Quimica Analitica, Facultad de Quimica, Bioquimica y Farmacia, Universidad Nacional de San Luis (Argentina); Wuilloud, Rodolfo G., E-mail: rwuilloud@mendoza-conicet.gov.ar [Laboratory of Environmental Research and Services of Mendoza (LISAMEN), (CCT-CONICET-Mendoza), Av. Ruiz Leal S/N Parque General San Martin, CC. 131, M 5502 IRA Mendoza (Argentina); Instituto de Ciencias Basicas, Universidad Nacional de Cuyo, Mendoza (Argentina)

    2009-04-27

    A simple microextraction technique based on room temperature ionic liquids (RTILs) for trace V(IV) and V(V) species separation and preconcentration in water samples was developed in this work. Vanadium species microextraction was achieved with a minimal amount of the RTIL 1-butyl-3-methylimidazolium hexafluorophosphate ([C{sub 4}mim][PF{sub 6}]) as vanadium-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (V-5-Br-PADAP) complex. The speciation analysis was performed based on a modern technique defined as temperature-controlled ionic liquid dispersive liquid phase microextraction (TILDLME). The level of V(IV) species was calculated by difference of total V and V(V) levels. Selectivity among V species was obtained with the use of 1,2-cyclohexanediaminetetraacetic acid (CDTA) as masking agent. Determination of V was developed by direct injection of the RTIL phase into the electrothermal atomic absorption spectrometer (ETAAS). A preconcentration factor of 40 was achieved with only 2 mL of sample. The limit of detection (LOD) obtained under optimum conditions was 4.9 ng L{sup -1} and the relative standard deviation for 10 replicate determinations at the 0.5 {mu}g L{sup -1} V level was 4.3%, calculated at peak heights. A correlation coefficient of 0.9961 was achieved. The method was successfully applied for the speciation analysis of V in tap and river water samples.

  3. Double multiple-relaxation-time lattice Boltzmann model for solid-liquid phase change with natural convection in porous media

    CERN Document Server

    Liu, Qing

    2015-01-01

    In this paper, a double multiple-relaxation-time lattice Boltzmann model is developed for simulating transient solid-liquid phase change problems in porous media at the representative elementary volume scale. The model uses two different multiple-relaxation-time lattice Boltzmann equations, one for the flow field and the other for the temperature field with nonlinear latent heat source term. The model is based on the generalized non-Darcy formulation, and the solid-liquid phase change interface is traced through the liquid fraction which is determined by the enthalpy method. The model is validated by numerical simulations of conduction melting in a semi-infinite space, solidification in a semi-infinite corner, and convection melting in a square cavity filled with porous media. The numerical results demonstrate the efficiency and accuracy of the present model for simulating transient solid-liquid phase change problems in porous media.

  4. 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.

  5. Determination of metal ions in tea samples using task-specific ionic liquid-based ultrasound-assisted dispersive liquid-liquid microextraction coupled to liquid chromatography with ultraviolet detection.

    Science.gov (United States)

    Werner, Justyna

    2016-04-01

    Task-specific ionic liquid-based ultrasound-assisted dispersive liquid-liquid microextraction was used for the preconcentration of cadmium(II), cobalt(II), and lead(II) ions in tea samples, which were subsequently analyzed by liquid chromatography with UV detection. The proposed method of preconcentration is free of volatile organic compounds, which are often used as extractants and dispersing solvents in classic techniques of microextraction. A task-specific ionic liquid trioctylmethylammonium thiosalicylate was used as an extractant and a chelating agent. Ultrasound was used to disperse the ionic liquid. After microextraction, the phases were separated by centrifugation, and the ionic liquid phase was solubilized in methanol and directly injected into the liquid chromatograph. Selected microextraction parameters, such as the volume of ionic liquid, the pH of the sample, the duration of ultrasound treatment, the speed and time of centrifugation, and the effect of ionic strength, were optimized. Under optimal conditions an enrichment factor of 200 was obtained for each analyte. The limits of detection were 0.002 mg/kg for Cd(II), 0.009 mg/kg for Co(II), and 0.013 mg/kg for Pb(II). The accuracy of the proposed method was evaluated by an analysis of the Certified Reference Materials (INCT-TL-1, INCT-MPH-2) with the recovery values in the range of 90-104%.

  6. X-ray powder diffraction analysis of liquid-phase-sintered silicon carbide ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz, A.L.; Sanchez-Bajo, F. [Universidad de Extremadura, Badajoz (Spain). Dept. de Electronica e Ingenieria Electromecanica; Cumbrera, F.L. [Universidad de Extremadura, Badajoz (Spain). Dept. de Fisica

    2002-07-01

    In an attempt to gain a comprehensive understanding of the microstructural evolution in liquid-phase-sintered silicon carbide ceramics, the effect of the starting {beta}-SiC powder has been studied. Pellets of two different {beta}-SiC starting powders were sintered with simultaneous additions of Al{sub 2}O{sub 3} and Y{sub 2}O{sub 3} at 1950 C for 1 hour in flowing argon atmosphere. Here we have used X-ray diffraction to obtain the relative abundance of the resulting SiC polytypes after sintering. The significant influence of the defects concentration on the {beta} to {alpha} transformation rate has been determined using the Rietveld method. (orig.)

  7. Application of Block Copolymer in Three-Liquid-Phase Extraction System

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A novel three-liquid-phase extraction system (TES) composed of butyl acetate, block copolymer polyethylene oxide-polypropylene oxide-polyethylene oxide and ammonium sulphate aqueous solution [(NH4)2SO4] as top, middle, and bottom phase, respectively, has been developed. The copolymer recycling and partitioning behavior of penicillin V has been studied in this system. Results show that the copolymer could be purified and recycled and penicillin V of the filtrated ferment broth could be partitioned unevenly among the phases and purified in the top phase of this TES. About 90 wt.% of penicillin V could be distributed into the top phase around pH 2.5 and only less than 0.1 wt.% left in the bottom phase.

  8. Liquid-phase-deposited siloxane-based capping layers for silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Veith-Wolf, Boris [Institute for Solar Energy Research Hamelin (ISFH), Am Ohrberg 1, 31860 Emmerthal (Germany); Wang, Jianhui; Hannu-Kuure, Milja; Chen, Ning; Hadzic, Admir; Williams, Paul; Leivo, Jarkko; Karkkainen, Ari [Optitune International Pte. Ltd., 20 Maxwell Road, #05-08 Maxwell House, Singapore 069113 (Singapore); Schmidt, Jan [Institute for Solar Energy Research Hamelin (ISFH), Am Ohrberg 1, 31860 Emmerthal (Germany); Department of Solar Energy, Institute of Solid-State Physics, Leibniz University Hanover, Appelstrasse 2, 30167 Hanover (Germany)

    2015-02-02

    We apply non-vacuum processing to deposit dielectric capping layers on top of ultrathin atomic-layer-deposited aluminum oxide (AlO{sub x}) films, used for the rear surface passivation of high-efficiency crystalline silicon solar cells. We examine various siloxane-based liquid-phase-deposited (LPD) materials. Our optimized AlO{sub x}/LPD stacks show an excellent thermal and chemical stability against aluminum metal paste, as demonstrated by measured surface recombination velocities below 10 cm/s on 1.3 Ωcm p-type silicon wafers after firing in a belt-line furnace with screen-printed aluminum paste on top. Implementation of the optimized LPD layers into an industrial-type screen-printing solar cell process results in energy conversion efficiencies of up to 19.8% on p-type Czochralski silicon.

  9. Gas-liquid phase separation in oppositely charged colloids: stability and interfacial tension.

    Science.gov (United States)

    Fortini, Andrea; Hynninen, Antti-Pekka; Dijkstra, Marjolein

    2006-09-07

    We study the phase behavior and the interfacial tension of the screened Coulomb (Yukawa) restricted primitive model (YRPM) of oppositely charged hard spheres with diameter sigma using Monte Carlo simulations. We determine the gas-liquid and gas-solid phase transitions using free energy calculations and grand-canonical Monte Carlo simulations for varying inverse Debye screening length kappa. We find that the gas-liquid phase separation is stable for kappasigmaMonte Carlo simulations. The interfacial tension decreases upon increasing the range of the interaction. In particular, we find that simple scaling can be used to relate the interfacial tension of the YRPM to that of the restricted primitive model, where particles interact with bare Coulomb interactions.

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

    Science.gov (United States)

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

    2011-09-01

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

  11. Enthalpies of mixing of the liquid phase in the ternary system Ag-Au-Bi

    Energy Technology Data Exchange (ETDEWEB)

    Zoro, E. [Laboratoire de Chimie Physique Minerale et Bioinorganique, EA401, Fac. Pharm., Universite de Paris XI, 5 rue JB Clement, 92296 Chatenay Malabry (France) and Laboratoire de Physico-Chimie de l' Etat Solide, UMR 8648, Bat 410-415, 91405 Orsay Cedex (France)]. E-mail: zoroe@netcourrier.com; Boa, D. [Laboratoire de Thermodynamique et de Physico-Chimie du Milieu, Universite d' Abobo-Adjame, UFR-SFA, 02 BP801 Abidjan 02, Cote d' Ivoire, Africa (Ivory Coast); Servant, C. [Laboratoire de Physico-Chimie de l' Etat Solide, UMR 8648, Bat 410-415, 91405 Orsay Cedex (France); Legendre, B. [Laboratoire de Chimie Physique Minerale et Bioinorganique, EA401, Fac. Pharm., Universite de Paris XI, 5 rue JB Clement, 92296 Chatenay Malabry (France)

    2005-08-02

    The enthalpies of mixing of the liquid phase of the Ag-Au-Bi ternary alloys along the sections Ag {sub x}Bi{sub 1-x}-Au (x = 0.11, 0.10 and 0.24) and Au {sub x}Bi{sub 1-x}-Ag (x = 0.11 and 0.27) have been determined at 673 and 773 K. We used a SETARAM devised heat flow calorimeter of Tian-Calvet type. The values obtained are almost compatible with estimations from Scientific Group of Thermodata Europe (SGTE) binary database without adding ternary thermodynamic excess parameters. However, slight discrepancies are observed. The result of this study is useful tools for the Ag-Au-Bi ternary system thermodynamic computer optimization in process by the authors.

  12. Strength and reliability of low temperature transient liquid phase bonded Cu-Sn-Cu interconnects

    DEFF Research Database (Denmark)

    Brincker, Mads; Söhl, Stefan; Eisele, Ronald

    2017-01-01

    as a potential technology that could enable the realization of stacks with better thermal performance and reliability than those can be achieved using conventional soldering techniques. Low temperature TLP bonded CuSnCu samples are fabricated, and the strength of the achieved bonds is measured by shear testing......As power electronic devices have tendencies to operate at higher temperatures and current densities, the demand for reliable and efficient packaging technologies are ever increasing. This paper reports the studies on application of transient liquid phase (TLP) bonding of CuSnCu systems...... for achieving a strong and high temperature resistant bond. Finally, initial results from a thermal cycling test are presented and it is concluded that the achieved TLP bonding is a promising candidate for the fabrication of reliable interconnects in power electronics....

  13. Liquid Phase Plasma Synthesis of Iron Oxide/Carbon Composite as Dielectric Material for Capacitor

    Directory of Open Access Journals (Sweden)

    Heon Lee

    2014-01-01

    Full Text Available Iron oxide/carbon composite was synthesized using a liquid phase plasma process to be used as the electrode of supercapacitor. Spherical iron oxide nanoparticles with the size of 5~10 nm were dispersed uniformly on carbon powder surface. The specific capacitance of the composite increased with increasing quantity of iron oxide precipitate on the carbon powder up to a certain quantity. When the quantity of the iron oxide precipitate exceeds the threshold, however, the specific capacitance was rather reduced by the addition of precipitate. The iron oxide/carbon composite containing an optimum quantity (0.33 atomic % of iron oxide precipitate exhibited the smallest resistance and the largest initial resistance slope.

  14. A liquid phase blocking ELISA for the detection of antibodies against infectious bronchitis virus

    Directory of Open Access Journals (Sweden)

    Cardoso T.C.

    1999-01-01

    Full Text Available A liquid phase blocking ELISA (LPB-ELISA was developed for the detection and measurement of antibodies against infectious bronchitis virus (IBV. The purified and nonpurified virus used as antigen, the capture and detector antibodies, and the chicken hyperimmune sera were prepared and standardized for this purpose. A total of 156 sera from vaccinated and 100 from specific pathogen-free chickens with no recorded contact with the virus were tested. The respective serum titers obtained in the serum neutralization test (SNT were compared with those obtained in the LPB-ELISA. There was a high correlation (r2 = 0.8926 between the two tests. The LPB-ELISA represents a single test suitable for the rapid detection of antibodies against bronchitis virus in chicken sera, with good sensitivity (88%, specificity (100% and agreement (95.31%.

  15. Low Temperature Coating of Anatase Thin Films on Silica Glass Fibers by Liquid Phase Deposition

    Institute of Scientific and Technical Information of China (English)

    LI Shun; LIU Jiachen; FENG Tiecheng

    2007-01-01

    Uniform crystalline TiO2 thin films were coated on silica glass fibers by liquid phase deposition from aqueous solution of ammonium hexafluorotitanate at low temperature. TiO2 thin films and nanopowders were prepared by adding H3BO3 into (NH4)2TiF6 solution supersaturated with anatase nano-crystalline TiO2 at 40 ℃. The effects of the deposition conditions on the surface morphology, section morphology, thickness of the deposited TiO2 thin films were investigated. The results indicate that the growth rate and particle size of the thin films were controlled by both the deposition conditions and the amount of anatase nano-crystalline TiO2.

  16. Liquid-phase chemical hydrogen storage: catalytic hydrogen generation under ambient conditions.

    Science.gov (United States)

    Jiang, Hai-Long; Singh, Sanjay Kumar; Yan, Jun-Min; Zhang, Xin-Bo; Xu, Qiang

    2010-05-25

    There is a demand for a sufficient and sustainable energy supply. Hence, the search for applicable hydrogen storage materials is extremely important owing to the diversified merits of hydrogen energy. Lithium and sodium borohydride, ammonia borane, hydrazine, and formic acid have been extensively investigated as promising hydrogen storage materials based on their relatively high hydrogen content. Significant advances, such as hydrogen generation temperatures and reaction kinetics, have been made in the catalytic hydrolysis of aqueous lithium and sodium borohydride and ammonia borane as well as in the catalytic decomposition of hydrous hydrazine and formic acid. In this Minireview we briefly survey the research progresses in catalytic hydrogen generation from these liquid-phase chemical hydrogen storage materials.

  17. Relationship between Liquid Phase Content and the Orientation of PMNT Ceramics by TGG Method

    Institute of Scientific and Technical Information of China (English)

    CAO Minghe; LI Dongliang; HAO Hua; LIU Hanxing

    2007-01-01

    The effects of glass frit on the sintering and electric properties of PMN-PT textured ceramics were investigated. The glass frits, including PbO, Bi2O3 and ZnO, were selected since liquid phase sintering lowered the PMN-PT sintering temperature. The piezoelectric properties of PMN-PT ceramics with glass frit addition are strongly dependent on the densification. The addition of glass frits into PMN-PT matrix reduced the sintering temperature to 1 100 ℃ instead of 1 150 ℃ for samples without glass. The piezoelectric coefficients(d33) of PMN-PT textured ceramics achieved 568 pc/N with 1 wt% excess PbO.

  18. Photoelectrochemical activity of liquid phase deposited TiO2 film for degradation of benzotriazole.

    Science.gov (United States)

    Ding, Yaobin; Yang, Changzhu; Zhu, Lihua; Zhang, Jingdong

    2010-03-15

    TiO(2) film deposited on glassy carbon electrode surface was prepared via the liquid phase deposition (LPD). The deposited TiO(2) film before and after calcination was characterized with scanning electron microscopy (SEM) and X-ray diffraction (XRD). Based on the high photoelectrochemical activity of calcined LPD TiO(2) film, the photoelectrocatalytic degradation of benzotriazole (BTA) was investigated. Compared with the electrochemical oxidation process, direct photolysis or photocatalysis for treatment of BTA, a synergetic photoelectrocatalytic degradation effect was observed using the LPD TiO(2) film-coated electrode. Various factors influencing the photoelectrocatalytic degradation of BTA such as film calcination, applied bias potential, pH value, supporting electrolyte concentration and initial concentration of BTA were investigated. The COD removal for BTA solution was analyzed to evaluate the mineralization of the PEC process. Based on the degradation experimental results, a possible photoelectrocatalytic degradation mechanism for BTA was proposed.

  19. Photoelectrochemical activity of liquid phase deposited TiO{sub 2} film for degradation of benzotriazole

    Energy Technology Data Exchange (ETDEWEB)

    Ding Yaobin [College of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan 430074 (China); Yang Changzhu [College of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Zhu Lihua [College of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan 430074 (China); Zhang Jingdong, E-mail: zhangjd@mail.hust.edu.cn [College of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan 430074 (China)

    2010-03-15

    TiO{sub 2} film deposited on glassy carbon electrode surface was prepared via the liquid phase deposition (LPD). The deposited TiO{sub 2} film before and after calcination was characterized with scanning electron microscopy (SEM) and X-ray diffraction (XRD). Based on the high photoelectrochemical activity of calcined LPD TiO{sub 2} film, the photoelectrocatalytic degradation of benzotriazole (BTA) was investigated. Compared with the electrochemical oxidation process, direct photolysis or photocatalysis for treatment of BTA, a synergetic photoelectrocatalytic degradation effect was observed using the LPD TiO{sub 2} film-coated electrode. Various factors influencing the photoelectrocatalytic degradation of BTA such as film calcination, applied bias potential, pH value, supporting electrolyte concentration and initial concentration of BTA were investigated. The COD removal for BTA solution was analyzed to evaluate the mineralization of the PEC process. Based on the degradation experimental results, a possible photoelectrocatalytic degradation mechanism for BTA was proposed.

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

    Science.gov (United States)

    Elliott, Douglas C; Oyler, James

    2013-12-17

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

  1. Separation of selected stable isotopes by liquid-phase thermal diffusion and by chemical exchange

    Science.gov (United States)

    Rutherford, W. M.; Jepson, B. E.; Michaels, E. D.

    Useful applications of enriched stable nuclides are unduly restricted by high cost and limited availability. Recent research on liquid phase thermal diffusion (LTD) has resulted in practical processes for separating S34, CL35, and CL37 in significant quantities (100 to 500 g/yr) at costs much lower than those associated with the electromagnetic (Calutron) process. The separation of the isotopes of bromine by LTD is now in progress and BR79 is being produced in relatively simple equivalent at a rate on the order of 0.5 g/day. The results of recent measurements show that the isotopes of Zn can be separated by LTD of zinc alkyls. The isotopes of calcium can be separated by LTD and by chemical exchange. The LTD process is based on the use of aqueous Ca(NO3)2 as a working fluid.

  2. Spin-liquid phase in a spin-1/2 quantum magnet on the kagome lattice

    Science.gov (United States)

    Isakov, Sergei; Kim, Yong Baek; Paramekanti, Arun

    2007-03-01

    We study a model of hard-core bosons with short-range repulsive interactions at half filling on the kagome lattice. This model is equivalent to an easy-axis spin-1/2 quantum model with no special conservation laws. Using quantum Monte Carlo numerics, we find that this model exhibits a continuous superfluid-insulator quantum phase transition, with exponents z=1 and ν=0.67(5). We show unambiguously that the insulator is a Z2 fractionalized spin liquid phase with short-ranged density and bond correlations, topological order, and exponentially decaying spatial vison correlations. In addition, we map out the finite temperature phase diagram. A Kosterlitz-Thouless finite temperature superfluid-insulator transition becomes strongly first order as the strength of the repulsive interactions increases. This is consistent with the zero temperature transition to the fractionalized phase.

  3. Characterization of Bimetallic Fe-Ru Oxide Nanoparticles Prepared by Liquid-Phase Plasma Method

    Science.gov (United States)

    Lee, Sung-Jin; Lee, Heon; Jeon, Ki-Joon; Park, Hyunwoong; Park, Young-Kwon; Jung, Sang-Chul

    2016-07-01

    The bimetallic Fe-Ru oxide nanoparticles were synthesized in the liquid-phase plasma (LPP) method which employed iron chloride and ruthenium chloride as precursors. The active species (OH·, Hα, Hβ, and OI) and the iron and ruthenium ions were observed in the plasma field created by the LPP process. The spherical-shaped bimetallic Fe-Ru oxide nanoparticles were synthesized by the LPP reaction, and the size of the particles was growing along with the progression of the LPP reaction. The synthesized bimetallic Fe-Ru oxide nanoparticles were comprised of Fe2O3, Fe3O4, RuO, and RuO2. Ruthenium had a higher reduction potential than iron and resulted in higher ruthenium composition in the synthesized bimetallic nanoparticles. The control of the molar ratio of the precursors in the reactant solution was found to be employed as a means to control the composition of the elements in bimetallic nanoparticles.

  4. Transient liquid phase diffusion bonding of a single crystal superalloy DD6

    Institute of Scientific and Technical Information of China (English)

    Li Xiaohong; Mao Wei; Guo Wanlin; Xie Yonghui; Ye Lei; Cheng Yaoyong

    2005-01-01

    DD6 alloy was bonded by transient liquid phase (TLP) diffusion bonding. The main compositions of the interlayer alloy employed were similar to those of the base metal, DD6, and a certain amount of element B was added as the melting point depressant. The results show that it is difficult to obtain the joints with the microstructures completely homogeneous. For the joint TLP diffusion bonded at 1 290℃ for 12 h, about half areas of the beam possessed a y + y' microstructure, nearly identical with that of the base metal, and the other local areas consisted of γ-solution, borides, etc. Prolonging the bonding time to 24 h, the inhomogeneous areas in the joint reduced, and the joint property improved. The joint stress-rupture strength at 980℃ and 1 100℃ reached90%-100% and 70%-80% of those of the base metal respectively.

  5. Improving Heterogeneous Catalyst Stability for Liquid-phase Biomass Conversion and Reforming.

    Science.gov (United States)

    Héroguel, Florent; Rozmysłowicz, Bartosz; Luterbacher, Jeremy S

    2015-01-01

    Biomass is a possible renewable alternative to fossil carbon sources. Today, many bio-resources can be converted to direct substitutes or suitable alternatives to fossil-based fuels and chemicals. However, catalyst deactivation under the harsh, often liquid-phase reaction conditions required for biomass treatment is a major obstacle to developing processes that can compete with the petrochemical industry. This review presents recently developed strategies to limit reversible and irreversible catalyst deactivation such as metal sintering and leaching, metal poisoning and support collapse. Methods aiming to increase catalyst lifetime include passivation of low-stability atoms by overcoating, creation of microenvironments hostile to poisons, improvement of metal stability, or reduction of deactivation by process engineering.

  6. Dopamine/TiO{sub 2} hybrid thin films prepared by the liquid phase deposition method

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez-Tauste, David [Departament de Quimica, Universitat Autonoma de Barcelona, Campus UAB, Edifici Cn, 08290 Cerdanyola del Valles, Barcelona (Spain)], E-mail: davidg@qf.uab.es; Domenech, Xavier [Departament de Quimica, Universitat Autonoma de Barcelona, Campus UAB, Edifici Cn, 08290 Cerdanyola del Valles, Barcelona (Spain); Domingo, Concepcion [Instituto de Ciencia de Materiales (CSIC), Campus UAB, 08290 Cerdanyola del Valles, Barcelona (Spain); Ayllon, Jose A. [Departament de Quimica, Universitat Autonoma de Barcelona, Campus UAB, Edifici Cn, 08290 Cerdanyola del Valles, Barcelona (Spain)

    2008-04-30

    Liquid phase deposition method is applied to one-step production of a hybrid material composed by dopamine(DA) and TiO{sub 2} anatase. An optimized amount of the enediol derivative is added to a fluoride titania precursor aqueous solution in order to entrap this modifier within the growing TiO{sub 2}, yielding a DA/TiO{sub 2} nanocomposite material. Uniform, well-adhered and brown-colored thin films are deposited on indium tin oxide covered glass substrate. The DA/TiO{sub 2} hybrid material has been characterized by infrared spectroscopy, electronic microscopy, X-ray diffraction and UV-vis spectroscopy. The formation of the hybrid material seems to be reasonably explained by linkage of different TiO{sub 2} nanocrystallites taking advantage of both enediol and amine groups of DA.

  7. A novel series of isoreticular metal organic frameworks: Realizing metastable structures by liquid phase epitaxy

    KAUST Repository

    Liu, Jinxuan

    2012-12-04

    A novel class of metal organic frameworks (MOFs) has been synthesized from Cu-acetate and dicarboxylic acids using liquid phase epitaxy. The SURMOF-2 isoreticular series exhibits P4 symmetry, for the longest linker a channel-size of 3 3 nm2 is obtained, one of the largest values reported for any MOF so far. High quality, ab-initio electronic structure calculations confirm the stability of a regular packing of (Cu++) 2-carboxylate paddle-wheel planes with P4 symmetry and reveal, that the SURMOF-2 structures are in fact metastable, with a fairly large activation barrier for the transition to the bulk MOF-2 structures exhibiting a lower, twofold (P2 or C2) symmetry. The theoretical calculations also allow identifying the mechanism for the low-temperature epitaxial growth process and to explain, why a synthesis of this highly interesting, new class of high-symmetry, metastable MOFs is not possible using the conventional solvothermal process.

  8. Grain growth kinetics in liquid-phase-sintered zinc oxide-barium oxide ceramics

    Science.gov (United States)

    Yang, Sung-Chul; German, Randall M.

    1991-01-01

    Grain growth of ZnO in the presence of a liquid phase of the ZnO-BaO system has been studied for temperatures from 1300 to 1400 C. The specimens were treated in boiling water and the grains were separated by dissolving the matrix phase in an ultrasonic bath. As a consequence 3D grain size measurements were possible. Microstructural examination shows some grain coalescence with a wide range of neck size ratios and corresponding dihedral angles, however, most grains are isolated. Lognormal grain size distributions show similar shapes, indicating that the growth mechanism is invariant over this time and temperature. All regressions between G exp n and time for n = 2 and 3 proved statistically significant. The rate constants calculated with the growth exponent set to n = 3 are on the same order of magnitude as in metallic systems. The apparent activation energy for growth is estimated between 355 and 458 kJ/mol.

  9. Supercritical supersaturations and ultrafast cooling of the growth solution in liquid-phase epitaxy of semiconductors

    Science.gov (United States)

    Abramov, A. V.; Deryagin, N. G.; Tret'yakov, D. N.

    1996-04-01

    A method for accomplishing ultrafast cooling is proposed which makes possible supercritical supersaturations of the growth solution in liquid-phase epitaxy. Growth boat designs providing cooling rates as high as 0268-1242/11/4/025/img1 are considered. The temperatures of contact, 0268-1242/11/4/025/img2, of a GaAs substrate with a Ga-based solution and of a Si substrate with a Sn-based growth solution, calculated for various substrate 0268-1242/11/4/025/img3 and solution temperatures 0268-1242/11/4/025/img4, are in good agreement with experimental values. The maximum attainable supercooling is markedly increased to as high as 0268-1242/11/4/025/img5 for the Ga - As system, when the growth solution is subjected to ultrafast cooling. The prospects of using the method for fabricating heterostructures with a large lattice mismatch are discussed.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-05-15

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

  11. Compressive deformation of liquid phase-sintered porous silicon carbide ceramics

    Directory of Open Access Journals (Sweden)

    Taro Shimonosono

    2014-12-01

    Full Text Available Porous silicon carbide ceramics were fabricated by liquid phase sintering with 1 wt% Al2O3–1 wt% Y2O3 additives during hot-pressing at 1400–1900 °C. The longitudinal strain at compressive fracture increased at a higher porosity and was larger than the lateral strain. The compressive Young's modulus and the strain at fracture depended on the measured direction, and increased with the decreased specific surface area due to the formation of grain boundary. However, the compressive strength and the fracture energy were not sensitive to the measured direction. The compressive strength of a porous SiC compact increased with increasing grain boundary area. According to the theoretical modeling of the strength–grain boundary area relation, it is interpreted that the grain boundary of a porous SiC compact is fractured by shear deformation rather than by compressive deformation.

  12. Photopeak detection by an InSb radiation detector made of liquid phase epitaxially grown crystals

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Yuki, E-mail: Y.Sato@nucleng.kyoto-u.ac.j [Graduate School of Engineering, Kyoto University, Sakyo, Kyoto 606-8501 (Japan); Morita, Yasunari; Harai, Tomoyuki; Kanno, Ikuo [Graduate School of Engineering, Kyoto University, Sakyo, Kyoto 606-8501 (Japan)

    2010-09-21

    We have fabricated a radiation detector using a p-type InSb crystal grown by liquid phase epitaxy (LPE). At temperatures below 100 K, the resistivity of the LPE crystal was over an order of magnitude higher than that of the commercial InSb crystal substrate. The resistance of the InSb detector is 680 k{Omega} at 4.2 K, which is one order of magnitude higher than that of detectors fabricated from commercial InSb wafers and, in an improvement over previous results, the energy resolution of {sup 241}Am alpha particles reaches 3%. In addition, we also observe the photopeak of gamma-rays emitted by {sup 133}Ba.

  13. Liquid-phase Hydrogenation of Phenol to Cyclohexanone over Supported Palladium Catalysts

    Directory of Open Access Journals (Sweden)

    Lihui Fan

    2016-10-01

    Full Text Available The ZSM-5, g-Al2O3, SiO2 and MgO supported Pd-catalysts were prepared for the phenol hydrogenation to cyclohexanone in liquid-phase. The natures of these catalysts were characterized by XRD, N2 adsorption-desorption analysis, H2-TPR, CO2-TPD and NH3-TPD. The catalytic performance of the supported Pd-catalyst for phenol hydrogenation to cyclohexanone is closely related to nature of the support and the size of Pd nanoparticles. The Pd/MgO catalyst which possesses higher basicity shows higher cyclohexanone selectivity, but lower phenol conversion owing to the lower specific surface area. The Pd/SiO2 catalyst prepared by precipitation gives higher cyclohexanone selectivity and phenol conversion, due to the moderate amount of Lewis acidic sites, and the smaller size and higher dispersion of Pd nanoparticles on the surface. Under the reaction temperature of 135 oC and H2 pressure of 1 MPa, after reacting for 3.5 h, the phenol conversion of 71.62% and the cyclohexanone selectivity of 90.77% can be obtained over 0.5 wt% Pd/SiO2 catalyst. Copyright © 2016 BCREC GROUP. All rights reserved Received: 7th March 2016; Revised: 13rd May 2016; Accepted: 7th June 2016 How to Cite: Fan, L., Zhang, L., Shen, Y., Liu, D., Wahab, N., Hasan, M.M. (2016. Liquid-phase Hydrogenation of Phenol to Cyclohexanone over Supported Palladium Catalysts. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (3: 354-362 (doi: 10.9767/bcrec.11.3.575.354-362 Permalink/DOI: http://doi.org/10.9767/bcrec.11.3.575.354-362

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

    Science.gov (United States)

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

    1999-04-01

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

  15. Identification of liquid-phase decomposition species and reactions for guanidinium azotetrazolate

    Energy Technology Data Exchange (ETDEWEB)

    Kumbhakarna, Neeraj R.; Shah, Kaushal J.; Chowdhury, Arindrajit; Thynell, Stefan T., E-mail: thynell@psu.edu

    2014-08-20

    Highlights: • Guanidinium azotetrazolate (GzT) is a high-nitrogen energetic material. • FTIR spectroscopy and ToFMS spectrometry were used for species identification. • Quantum mechanics was used to identify transition states and decomposition pathways. • Important reactions in the GzT liquid-phase decomposition process were identified. • Initiation of decomposition occurs via ring opening, releasing N{sub 2}. - Abstract: The objective of this work is to analyze the decomposition of guanidinium azotetrazolate (GzT) in the liquid phase by using a combined experimental and computational approach. The experimental part involves the use of Fourier transform infrared (FTIR) spectroscopy to acquire the spectral transmittance of the evolved gas-phase species from rapid thermolysis, as well as to acquire spectral transmittance of the condensate and residue formed from the decomposition. Time-of-flight mass spectrometry (ToFMS) is also used to acquire mass spectra of the evolved gas-phase species. Sub-milligram samples of GzT were heated at rates of about 2000 K/s to a set temperature (553–573 K) where decomposition occurred under isothermal conditions. N{sub 2}, NH{sub 3}, HCN, guanidine and melamine were identified as products of decomposition. The computational approach is based on using quantum mechanics for confirming the identity of the species observed in experiments and for identifying elementary chemical reactions that formed these species. In these ab initio techniques, various levels of theory and basis sets were used. Based on the calculated enthalpy and free energy values of various molecular structures, important reaction pathways were identified. Initiation of decomposition of GzT occurs via ring opening to release N{sub 2}.

  16. Cold flame on Biofilm - Transport of Plasma Chemistry from Gas to Liquid Phase

    Science.gov (United States)

    Kong, Michael

    2014-10-01

    One of the most active and fastest growing fields in low-temperature plasma science today is biological effects of gas plasmas and their translation in many challenges of societal importance such as healthcare, environment, agriculture, and nanoscale fabrication and synthesis. Using medicine as an example, there are already three FDA-approved plasma-based surgical procedures for tissue ablation and blood coagulation and at least five phase-II clinical trials on plasma-assisted wound healing therapies. A key driver for realizing the immense application potential of near room-temperature ambient pressure gas plasmas, commonly known as cold atmospheric plasmas or CAP, is to build a sizeable interdisciplinary knowledge base with which to unravel, optimize, and indeed design how reactive plasma species interact with cells and their key components such as protein and DNA. Whilst a logical objective, it is a formidable challenge not least since existing knowledge of gas discharges is largely in the gas-phase and therefore not directly applicable to cell-containing matters that are covered by or embedded in liquid (e.g. biofluid). Here, we study plasma inactivation of biofilms, a jelly-like structure that bacteria use to protect themselves and a major source of antimicrobial resistance. As 60--90% of biofilm is made of water, we develop a holistic model incorporating physics and chemistry in the upstream CAP-generating region, a plasma-exit region as a buffer for as-phase transport, and a downstream liquid region bordering the gas buffer region. A special model is developed to account for rapid chemical reactions accompanied the transport of gas-phase plasma species through the gas-liquid interface and for liquid-phase chemical reactions. Numerical simulation is used to illustrate how key reactive oxygen species (ROS) are transported into the liquid, and this is supported with experimental data of both biofilm inactivation using plasmas and electron spin spectroscopy (ESR

  17. Extending Tabletop XUV Spectroscopy to the Liquid Phase to Examine Transition Metal Catalysts

    Science.gov (United States)

    Benke, Kristin; Ryland, Elizabeth S.; Vura-Weis, Josh

    2017-06-01

    M-edge spectroscopy of first row transition metals (3p to 3d excitation) is the low energy analogue of more well-known K- and L-edge spectroscopy, but can be implemented without the use of a synchrotron. Instead, M-edge spectroscopy can be performed as a tabletop method, relying on high harmonic generation (HHG) to produce ultrashort (˜ 20 fs) pulses of extreme ultraviolet (XUV) light in the range of 10-100s of eV. We have shown tabletop M-edge spectroscopy to be a valuable tool in determining the electronic structure of metal-centered coordination complexes and have demonstrated its capacity to yield element-specific information about a compound's oxidation state, spin state, and ligand field. The power of this technique to distinguish these features makes it a promising addition to the arsenal of methods used to study metal-centered catalysts. A catalytic reaction can be initiated photochemically and the XUV probe can be used to track oxidative and structural changes to identify the key intermediates. Until recently tabletop XUV spectroscopy has been performed on thin film samples, but in order to examine homogeneous catalysis, the technique must be adapted to look at samples in the liquid phase. The challenges of adapting tabletop XUV spectroscopy to the liquid phase lie in the lower attenuation length of XUV light compared to soft and hard x-rays and the lower flux compared to synchrotron methods. As a result, the sample must be limited to a sub-micron thickness as well as isolated from the vacuum environment required for x-ray spectroscopy. I am developing a liquid flow cell that relies on confining the sample between two x-ray transmissive SiN membranes, as has been demonstrated for use at synchrotrons, but adapted to the unique difficulties encountered in tabletop XUV spectroscopy.

  18. Effect of the formation process of transient liquid phase (TLP) on the interface structure of TiAl joints

    Institute of Scientific and Technical Information of China (English)

    Huiping Duan; Jun Luo; Karl-Heinz Bohm; Mustafa Ko(c)ak

    2005-01-01

    TiAl has been joined employing the transient liquid phase (TLP) bonding with Ti combined with Cu, Ni or Fe foils. Experimental results showed that though the interface structures of the joints are quite different, all the joined zones are composed of five sublayers, i.e. two diffusion zones, two interfacial zones and an interlayer. It has been convinced that the formation process of the transient liquid phase controls the diffusion behavior of melting point depressant (MPD) Cu, Ni, and Fe atoms, which leads to form different interface structures of the joints.

  19. Mass transfer in the liquid-phase methanol synthesis (LPMeOH)/sup TM/ process: Interim report

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.; Parameswaran, V.R.; Sawant, A.V.; Ko, M.K.

    1988-04-01

    This report is a sequel to the Interim Report AP-4429 titled /open quote/Research to Support Development of the Liquid Phase Methanol Synthesis Process/close quote/ (LPMEOH/sup TM/ Process). The focus of this report is on the mass transfer characteristics of the process when the reaction is carried out in a stirred slurry reactor. The relevant aspects of mass transfer theory have been explained and supported with extensive experimental data. As such, this report provides the necessary database for scale-up and design of a stirred slurry reactor for liquid-phase methanol synthesis. 17 refs., 35 figs., 12 tabs.

  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. Order-parameter-aided temperature-accelerated sampling for the exploration of crystal polymorphism and solid-liquid phase transitions

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Tang-Qing, E-mail: tangqing.yu@nyu.edu; Vanden-Eijnden, Eric, E-mail: eve2@cims.nyu.edu [Courant Institute of Mathematical Sciences, New York University, New York, New York 10012 (United States); Chen, Pei-Yang; Chen, Ming [Department of Chemistry, New York University, New York, New York 10003 (United States); Samanta, Amit [Program in Applied and Computational Mathematics, Princeton University, Princeton, New Jersey 08544, USA and Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Tuckerman, Mark, E-mail: mark.tuckerman@nyu.edu [Courant Institute of Mathematical Sciences, New York University, New York, New York 10012 (United States); Department of Chemistry, New York University, New York, New York 10003 (United States); NYU-ECNU Center for Computational Chemistry at NYU Shanghai, Shanghai 200062 (China)

    2014-06-07

    The problem of predicting polymorphism in atomic and molecular crystals constitutes a significant challenge both experimentally and theoretically. From the theoretical viewpoint, polymorphism prediction falls into the general class of problems characterized by an underlying rough energy landscape, and consequently, free energy based enhanced sampling approaches can be brought to bear on the problem. In this paper, we build on a scheme previously introduced by two of the authors in which the lengths and angles of the supercell are targeted for enhanced sampling via temperature accelerated adiabatic free energy dynamics [T. Q. Yu and M. E. Tuckerman, Phys. Rev. Lett. 107, 015701 (2011)]. Here, that framework is expanded to include general order parameters that distinguish different crystalline arrangements as target collective variables for enhanced sampling. The resulting free energy surface, being of quite high dimension, is nontrivial to reconstruct, and we discuss one particular strategy for performing the free energy analysis. The method is applied to the study of polymorphism in xenon crystals at high pressure and temperature using the Steinhardt order parameters without and with the supercell included in the set of collective variables. The expected fcc and bcc structures are obtained, and when the supercell parameters are included as collective variables, we also find several new structures, including fcc states with hcp stacking faults. We also apply the new method to the solid-liquid phase transition in copper at 1300 K using the same Steinhardt order parameters. Our method is able to melt and refreeze the system repeatedly, and the free energy profile can be obtained with high efficiency.

  2. EPR spectroscopic studies of the process of interaction in a system of liquid phase of the plastic coal mass and thermally unstable carbon filler

    Energy Technology Data Exchange (ETDEWEB)

    Ikonomopulo, V.P.

    1983-01-01

    In conection with discovering the mechanism of coke formation, possible reactions of transient products of thermodestruction in liquid phase-thermally unstable carbon filler systems are studied. The investigations demonstrated that the liquid-phase transient products of one component of the mixture accelerated the process of plastification of solid transient products, and this in turn facilitated the development of the formation of ordered paramagnetic structures. The influence of non-plasticizing thermostable carbon fillers on the thermochemical conversions of liquid phase materials is similar to that of thermostable carbon fillers. A vapor-gas medium is the possible channel of reaction in a liquid phase-solid transient product system. (8 refs.)

  3. Microstructure-property relationships in digitally generated three-dimensional, two-phase, liquid phase sintered materials

    Science.gov (United States)

    Lee, Sukbin

    complete wetting of particles by matrix and the constraint that the site exchange for diffusion of voxels is allowed only for neighboring particle-matrix voxel pairs in the Monte Carlo Potts model, this model can also be used for modeling isotropic coarsening of solid particles during liquid phase sintering. Kinetic Monte Carlo simulation is used to probe the coarsening dynamics and to obtain the characteristics of the solid particles, including the volume of critical nuclei and the distribution of particle size as a function of time. It is found that the average particle volume increases linearly with time and that the particle size distributions are consistent with those obtained experimentally, as in liquid phase sintered W-Ni-Fe and Sn-Pb systems. In obtaining these results, careful consideration is given to the role of initial microstructural conditions in the subsequent evolution of the system. The other objective of this project is to explore the effect of individual microstructural parameters in the hypothetical two-phase microstructures, including ones from the proposed Monte Carlo coarsening simulation, on stress and strain rate fields when uniaxial tension is applied. Using those two-phase digital microstructures as inputs, the microstructure-property relationship study is performed using a viscoplastic simulation based on the Fast Fourier Transform (FFT) algorithm. In the simulations, the dispersed phase consists of hard BCC particles with random spatial orientations while the matrix phase is either (1) a single soft FCC crystal with a fixed spatial orientation or (2)a soft FCC polycrystalline structure with random spatial orientations. A systematic parametric study, varying selected microstructural parameters such as the volume fraction of phases, contiguity of particles and spatial distribution of particles, is employed in order to explore the mechanical response of the hypothetical microstructures under uniaxial tension. It is found that the contiguity of

  4. Rare-earth-ion doped KY(WO4)2 optical waveguides grown by liquid-phase epitaxy

    NARCIS (Netherlands)

    Romanyuk, Y.E.; Apostolopoulos, V.; Utke, U.; Pollnau, Markus

    2004-01-01

    High-quality KY(WO4)2 thin layers doped with rare-earth-ions were grown using liquid-phase epitaxy. A low-temperature mixture of chlorides was used as the flux and undoped KY(WO4)2 crystals as substrates. The crystalline layers possessed thicknesses up to 10 µm. Passive and active planar waveguiding

  5. The liquid phase epitaxy method for the construction of oriented ZIF-8 thin films with controlled growth on functionalized surfaces

    KAUST Repository

    Shekhah, Osama

    2013-01-01

    Highly-oriented ZIF-8 thin films with controllable thickness were grown on an -OH-functionalized Au substrate using the liquid phase epitaxy method at room temperature, as evidenced by SEM and PXRD. The adsorption-desorption properties of the resulting ZIF-8 thin film were investigated for various VOCs using the QCM technique. © The Royal Society of Chemistry 2013.

  6. 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.

  7. Determination of reactor operation for the microbial hydroxylation of toluene in a two-liquid phase process

    DEFF Research Database (Denmark)

    Collins, AM; Woodley, John; Liddell, JM

    1995-01-01

    to toluene cis-glycol by Pseudomonas putida UV4. Toxic effects may be eliminated through the introduction of tetradecane, to partition toluene away from the biocatalyst, to give product concentrations of 30-60 g L(-1), in a two-liquid-phase reactor. The operational limits of this system have been...

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

    Science.gov (United States)

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

    2014-07-23

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

  9. Selective liquid-phase oxidation of alcohols catalyzed by a silver-based catalyst promoted by the presence of ceria

    DEFF Research Database (Denmark)

    Beier, Matthias Josef; Hansen, Thomas Willum; Grunwaldt, Jan-Dierk

    2009-01-01

    A number of silver catalysts supported on SiO2, Al2O3, Celite, CeO2, kaolin, MgO, and activated carbon were screened for their catalytic activity in the selective liquid-phase oxidation of benzyl alcohol using a special screening approach. For this purpose 5–6 catalyst samples were mixed and tested...

  10. In situ growth of capping-free magnetic iron oxide nanoparticles on liquid-phase exfoliated graphene

    NARCIS (Netherlands)

    Tsoufis, T.; Syrgiannis, Z.; Akhtar, N.; Prato, M.; Katsaros, F.; Sideratou, Z.; Kouloumpis, A.; Gournis, D.; Rudolf, P.

    2015-01-01

    We report a facile approach for the in situ synthesis of very small iron oxide nanoparticles on the surface of high-quality graphene sheets. Our synthetic strategy involved the direct, liquid-phase exfoliation of highly crystalline graphite (avoiding any oxidation treatment) and the subsequent

  11. In situ growth of capping-free magnetic iron oxide nanoparticles on liquid-phase exfoliated graphene

    NARCIS (Netherlands)

    Tsoufis, T.; Syrgiannis, Z.; Akhtar, N.; Prato, M.; Katsaros, F.; Sideratou, Z.; Kouloumpis, A.; Gournis, D.; Rudolf, P.

    2015-01-01

    We report a facile approach for the in situ synthesis of very small iron oxide nanoparticles on the surface of high-quality graphene sheets. Our synthetic strategy involved the direct, liquid-phase exfoliation of highly crystalline graphite (avoiding any oxidation treatment) and the subsequent chemi

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

    NARCIS (Netherlands)

    J.O. Iregui; P. Corboz; M. Troyer

    2014-01-01

    We study the extent of the spin liquid phases in the Kitaev-Heisenberg model using infinite projected entangled-pair states tensor network ansatz wave functions directly in the thermodynamic limit. To assess the accuracy of the ansatz wave functions, we perform benchmarks against exact results for t

  13. Development of monolith with a carbon-nanofiber-washcoat as a structured catalyst support in liquid phase

    NARCIS (Netherlands)

    Jarrah, Nabeel A.; Ommen, van J.G.; Lefferts, L.

    2003-01-01

    Washcoats with improved mass transfer properties are necessary to circumvent concentration gradients in case of fast reactions in liquid phase, e.g. nitrate hydrogenation. A highly porous, high surface area (180 m2/g) and thin washcoat of carbon fibers, was produced on a monolith support by methane

  14. Microstructure and properties of liquid-phase sintered tungsten heavy alloys by using ultra-fine tungsten powders

    Institute of Scientific and Technical Information of China (English)

    于洋; 王尔德

    2004-01-01

    The microstructure and properties of liquid-phase sintered 93W-4.9Ni-2.1Fe tungsten heavy alloys using ultra-fine tungsten powders (medium particle size of 700 nm) and original tungsten powders (medium particle size of 3 μm) were investigated respectively. Commercial tungsten powders (original tungsten powders) were mechanically milled in a high-energy attritor mill for 35 h. Ultra-fine tungsten powders and commercial Ni, Fe powders were consolidated into green compacts by using CIP method and liquid-phase sintering at 1 465 ℃ for 30 min in the dissociated ammonia atmosphere. Liquid-phase sintered tungsten heavy alloys using ultra-fine tungsten powders exhibit full densification (above 99% in relative density) and higher strength and elongation compared with conventional liquidphase sintered alloys using original tungsten powders due to lower sintering temperature at 1 465 ℃ and short sintering time. The mechanical properties of sintered tungsten heavy alloy are found to be mainly dependent on the particles size of raw tungsten powders and liquid-phase sintering temperature.

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

    Energy Technology Data Exchange (ETDEWEB)

    None

    1997-06-30

    The Liquid Phase Methanol (LPMEOHTM) Demonstration Project at Kingsport, Tennessee, is a $213.7 million cooperative agreement between the U.S. Department of Energy (DOE) and Air Products Liquid Phase Conversion Company, L.P. (the Partnership). Air Products and Chemicals, Inc. (Air Products) and Eastman Chemical Company (Eastman) formed the Partnership to execute the Demonstration Project. The LPMEOIYM Process Demonstration Unit was built at a site located at the Eastman complex in Kingsport. During this quarter, comments from the DOE on the Topical Report "Economic Analysis - LPMEOHTM Process as an Add-on to IGCC for Coproduction" were received. A recommendation to continue with design verification testing for the coproduction of dimethyl ether (DIME) and methanol was made. DME design verification testing studies show the liquid phase DME (LPDME) process will have a significant economic advantage for the coproduction of DME for local markets. An LPDME catalyst system with reasonable long-term activity and stability is being developed. A recommendation document summarizing catalyst targets, experimental results, and the corresponding economics for a commercially successful LPDME catalyst was issued on 30 June 1997. The off-site, product-use test plan was updated in June of 1997. During this quarter, Acurex Environmental Corporation and Air Products screened proposals for this task by the likelihood of the projects to proceed and the timing for the initial methanol requirement. Eight sites from the list have met these criteria. The formal submission of the eight projects for review and concurrence by the DOE will be made during the next reporting period. The site paving and final painting were completed in May of 1997. Start-up activities were completed during the reporting period, and the initial methanol production from the demonstration unit occurred on 02 April 1997. The first extended stable operation at the nameplate capacity of 80,000 gallons per day (260 tons

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

    Energy Technology Data Exchange (ETDEWEB)

    None

    1997-06-30

    The Liquid Phase Methanol (LPMEOHTM) Demonstration Project at Kingsport, Tennessee, is a $213.7 million cooperative agreement between the U.S. Department of Energy (DOE) and Air Products Liquid Phase Conversion Company, L.P. (the Partnership). Air Products and Chemicals, Inc. (Air Products) and Eastman Chemical Company (Eastman) formed the Partnership to execute the Demonstration Project. The LPMEOIYM Process Demonstration Unit was built at a site located at the Eastman complex in Kingsport. During this quarter, comments from the DOE on the Topical Report "Economic Analysis - LPMEOHTM Process as an Add-on to IGCC for Coproduction" were received. A recommendation to continue with design verification testing for the coproduction of dimethyl ether (DIME) and methanol was made. DME design verification testing studies show the liquid phase DME (LPDME) process will have a significant economic advantage for the coproduction of DME for local markets. An LPDME catalyst system with reasonable long-term activity and stability is being developed. A recommendation document summarizing catalyst targets, experimental results, and the corresponding economics for a commercially successful LPDME catalyst was issued on 30 June 1997. The off-site, product-use test plan was updated in June of 1997. During this quarter, Acurex Environmental Corporation and Air Products screened proposals for this task by the likelihood of the projects to proceed and the timing for the initial methanol requirement. Eight sites from the list have met these criteria. The formal submission of the eight projects for review and concurrence by the DOE will be made during the next reporting period. The site paving and final painting were completed in May of 1997. Start-up activities were completed during the reporting period, and the initial methanol production from the demonstration unit occurred on 02 April 1997. The first extended stable operation at the nameplate capacity of 80,000 gallons per day (260 tons

  17. Liquid-liquid-solid microextraction based on membrane-protected molecularly imprinted polymer fiber for trace analysis of triazines in complex aqueous samples.

    Science.gov (United States)

    Hu, Yuling; Wang, Yangyang; Hu, Yufei; Li, Gongke

    2009-11-20

    A novel liquid-liquid-solid microextraction (LLSME) technique based on porous membrane-protected molecularly imprinted polymer (MIP)-coated silica fiber has been developed. In this technique, a MIP-coated silica fiber was protected with a length of porous polypropylene hollow fiber membrane which was filled with water-immiscible organic phase. Subsequently the whole device was immersed into aqueous sample for extraction. The LLSME technique was a three-phase microextraction approach. The target analytes were firstly extracted from the aqueous sample through a few microliters of organic phase residing in the pores and lumen of the membrane, and were then finally extracted onto the MIP fiber. A terbutylazine MIP-coated silica fiber was adopted as an example to demonstrate the feasibility of the novel LLSME method. The extraction parameters such as the organic solvent, extraction and desorption time were investigated. Comparison of the LLSME technique was made with molecularly imprinted polymer based solid-phase microextraction (MIP-SPME) and hollow fiber membrane-based liquid-phase microextraction (HF-LPME), respectively. The LLSME, integrating the advantages of high selectivity of MIP-SPME and enrichment and sample cleanup capability of the HF-LPME into a single device, is a promising sample preparation method for complex samples. Moreover, the new technique overcomes the problem of disturbance from water when the MIP-SPME fiber was exposed directly to aqueous samples. Applications to analysis of triazine herbicides in sludge water, watermelon, milk and urine samples were evaluated to access the real sample application of the LLSME method by coupling with high-performance liquid chromatography (HPLC). Low limits of detection (0.006-0.02 microg L(-1)), satisfactory recoveries and good repeatability for real sample (RSD 1.2-9.6%, n = 5) were obtained. The method was demonstrated to be a fast, selective and sensitive pretreatment method for trace analysis of triazines

  18. 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

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

    Science.gov (United States)

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

  20. Dilute GaAsN and GaInAsN grown by liquid phase epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Milanova, M; Koleva, G; Kakanakov, R [Central Laboratory of Applied Physics, Bulgarian Academy of Sciences, 59 St. Petersburg Blvd, 4000 Plovdiv (Bulgaria); Vitanov, P K; Alexieva, Z; Goranova, E A [Central Laboratory of Solar Energy and New Energy Sources, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee, 1784 Sofia (Bulgaria); Arnaudov, B; Evtimova, S [Faculty of Physics, St. Kl. Ohridski University of Sofia, 5 J. Bourchier Blvd, 1164 Sofia (Bulgaria); Barthou, C; Clerjaud, B, E-mail: vitanov@phys.bas.b [Universite Pierre et Marie Curie, Institut des NanoSciences de Paris, rue de Lourmel 140, 75015 Paris (France)

    2010-04-01

    Dilute III-nitrides, such as GaAsN and GaInAsN, are of considerable current interest both from a fundamental point of view and for applications in solar cells, GaAs-based long-wavelength photodetectors and diode lasers. The addition of nitrogen leads to material properties that deviate strongly from those expected for conventional III-V solid solutions. The possibility was investigated to use liquid phase epitaxy to incorporate nitrogen in epitaxial GaAsN/GaAs and GaInAsN/GaAs heterostructures. The structures were grown from Ga- and Ga-In- melts containing powder GaN as a nitrogen source. The initial growth temperature was varied in the range 560{sup 0}C - 660{sup 0}C. The low temperature growth favors nitrogen incorporation in the epilayers. The optical transmission and photoluminescence spectra of a set of structures grown at different temperatures were studied showing ternary and quaternary dilute nitride solid solutions with nitrogen content about 0.2 at.%. The photoluminescence spectra show emission from localized nitrogen states as well.

  1. Dilute GaAsN and GaInAsN grown by liquid phase epitaxy

    Science.gov (United States)

    Milanova, M.; Koleva, G.; Kakanakov, R.; Vitanov, P. K.; Alexieva, Z.; Goranova, E. A.; Arnaudov, B.; Evtimova, S.; Barthou, C.; Clerjaud, B.

    2010-04-01

    Dilute III-nitrides, such as GaAsN and GaInAsN, are of considerable current interest both from a fundamental point of view and for applications in solar cells, GaAs-based long-wavelength photodetectors and diode lasers. The addition of nitrogen leads to material properties that deviate strongly from those expected for conventional III-V solid solutions. The possibility was investigated to use liquid phase epitaxy to incorporate nitrogen in epitaxial GaAsN/GaAs and GaInAsN/GaAs heterostructures. The structures were grown from Ga- and Ga-In- melts containing powder GaN as a nitrogen source. The initial growth temperature was varied in the range 560°C - 660°C. The low temperature growth favors nitrogen incorporation in the epilayers. The optical transmission and photoluminescence spectra of a set of structures grown at different temperatures were studied showing ternary and quaternary dilute nitride solid solutions with nitrogen content about 0.2 at.%. The photoluminescence spectra show emission from localized nitrogen states as well.

  2. A novel series of isoreticular metal organic frameworks: realizing metastable structures by liquid phase epitaxy

    Science.gov (United States)

    Liu, Jinxuan; Lukose, Binit; Shekhah, Osama; Arslan, Hasan Kemal; Weidler, Peter; Gliemann, Hartmut; Bräse, Stefan; Grosjean, Sylvain; Godt, Adelheid; Feng, Xinliang; Müllen, Klaus; Magdau, Ioan-Bogdan; Heine, Thomas; Wöll, Christof

    2012-01-01

    A novel class of metal organic frameworks (MOFs) has been synthesized from Cu-acetate and dicarboxylic acids using liquid phase epitaxy. The SURMOF-2 isoreticular series exhibits P4 symmetry, for the longest linker a channel-size of 3 × 3 nm2 is obtained, one of the largest values reported for any MOF so far. High quality, ab-initio electronic structure calculations confirm the stability of a regular packing of (Cu++)2- carboxylate paddle-wheel planes with P4 symmetry and reveal, that the SURMOF-2 structures are in fact metastable, with a fairly large activation barrier for the transition to the bulk MOF-2 structures exhibiting a lower, twofold (P2 or C2) symmetry. The theoretical calculations also allow identifying the mechanism for the low-temperature epitaxial growth process and to explain, why a synthesis of this highly interesting, new class of high-symmetry, metastable MOFs is not possible using the conventional solvothermal process. PMID:23213357

  3. The effect of residual chlorides on resultant properties of solid and liquid phases after carbonization process

    Energy Technology Data Exchange (ETDEWEB)

    Plevova Eva; Sugarkova Vera; Kaloc Miroslav [Institute of Geonics ASCR, Ostrava (Czech Republic). Laboratory of Petrology

    2004-07-01

    The low-concentration condition was employed to model the carbonisation mode for local (Czech Republic) coals with higher concentrations of some metals. After completing the carbonisation, mass balance calculations were performed. Results show that the presence of zinc dichloride, copper dichloride and sodium chloride caused the most pronounced impediment to the formation of tar in contrast to lead dichloride and aluminium chloride that increased tar. The results demonstrated that adding of chloride agents effect both the course of the coking process and the properties of solid and liquid products of coking. Evaluation of the solid phase showed that chloride addition caused a decrease of the caking and swelling value, which corresponds with measurements of plasticity values that are of significant influence on mechanical properties closely related to coking plant processes. Evaluation of the liquid phase pointed towards an increase of aromatic hydrocarbons and their derivatives (especially phenanthrene, fluoranthene, acenaphthylene, pyrene) but a decrease of naphthalene and methylnaphthalene. Chloride addition increased aromaticity and caused a difference in substitution rate at aromatic nucleus. Mesophase estimation indicated extensive mosaic, domain and laminated anisotropic texture occurrence after chloride addition, mainly NaCl and CuCl{sub 2} addition. A more detailed evaluation including detailed screening, TGA, IR and RTG analysis will be subject of further investigation. 4 refs., 2 figs., 5 tabs.

  4. Thermal Diffusivity and Thermal Conductivity of Five Different Steel Alloys in the Solid and Liquid Phases

    Science.gov (United States)

    Wilthan, B.; Schützenhöfer, W.; Pottlacher, G.

    2015-08-01

    The need for characterization of thermophysical properties of steel and nickel-based alloys was addressed in the FFG-Bridge Project 810999 in cooperation with a partner from industry, Böhler Edelstahl GmbH & Co KG. To optimize numerical simulations of production processes, such as remelting or plastic deformation, additional, and more accurate data were necessary for the alloys under investigation. With a fast ohmic pulse heating circuit system, the temperature-dependent specific electrical resistivity, density, and specific heat capacity for a set of five high alloyed steels were measured. Hence, using the Wiedemann-Franz law with a Lorenz number of , the thermal diffusivity and thermal conductivity could be calculated for the solid and liquid phases up to temperatures of 2500 K. This experimental approach is limited by the following requirements for the specimens: they have to be electrically conducting, the melting point has to be high enough for the implemented pyrometric temperature measurement, and one has to be able to draw wires of the material. The latter restriction is technologically challenging with some of the materials being very brittle. For all samples, electrical and temperature signals are recorded and a fast shadowgraph method is used to measure the volume expansion. For each material under investigation, a set of data including the chemical composition, the density at room temperature, solidus and liquidus temperatures, and the change of enthalpy, resistivity, density, thermal conductivity, and thermal diffusivity as a function of temperature is reported.

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

    Energy Technology Data Exchange (ETDEWEB)

    Olsen, Christopher Sean [Univ. of California, Berkeley, CA (United States)

    1998-05-01

    This research has shown that epilayers with residual impurity concentrations of 5 x 1013 cm-3 can be grown by producing the purest Pb available in the world. These epilayers have extremely low minority acceptor concentrations, which is ideal for fabrication of IR absorbing layers. The Pb LPE growth of Ge also has the advantageous property of gettering Cu from the epilayer and the substrate. Epilayers have been grown with intentional Sb doping for IR absorption on lightly doped substrates. This research has proven that properly working Ge BIB detectors can be fabricated from the liquid phase as long as pure enough solvents are available. The detectors have responded at proper wavelengths when reversed biased even though the response did not quite reach minimum wavenumbers. Optimization of the Sb doping concentration should further decrease the photoionization energy of these detectors. Ge BIB detectors have been fabricated that respond to 60 cm-1 with low responsivity. Through reduction of the minority residual impurities, detector performance has reached responsivities of 1 A/W. These detectors have exhibited quantum efficiency and NEP values that rival conventional photoconductors and are expected to provide a much more sensitive tool for new scientific discoveries in a number of fields, including solid state studies, astronomy, and cosmology.

  6. Room temperature ferromagnetism in liquid-phase pulsed laser ablation synthesized nanoparticles of nonmagnetic oxides

    Energy Technology Data Exchange (ETDEWEB)

    Singh, S. C., E-mail: subhash.laserlab@gmail.com; Gopal, R. [Laser Spectroscopy and Nanomaterials Lab, Department of Physics, University of Allahabad, Allahabad-211002 (India); Kotnala, R. K. [Magnetic Standardization Division, National Physical Laboratory, K.S. Krishnan Road, New Delhi (India)

    2015-08-14

    Intrinsic Room Temperature Ferromagnetism (RTF) has been observed in undoped/uncapped zinc oxide and titanium dioxide spherical nanoparticles (NPs) obtained by a purely green approach of liquid phase pulsed laser ablation of corresponding metal targets in pure water. Saturation magnetization values observed for zinc oxide (average size, 9 ± 1.2 nm) and titanium dioxide (average size, 4.4 ± 0.3 nm) NPs are 62.37 and 42.17 memu/g, respectively, which are several orders of magnitude larger than those of previous reports. In contrast to the previous works, no postprocessing treatments or surface modification is required to induce ferromagnetism in the case of present communication. The most important result, related to the field of intrinsic ferromagnetism in nonmagnetic materials, is the observation of size dependent ferromagnetism. Degree of ferromagnetism in titanium dioxide increases with the increase in particle size, while it is reverse for zinc oxide. Surface and volume defects play significant roles for the origin of RTF in zinc oxide and titanium dioxide NPs, respectively. Single ionized oxygen and neutral zinc vacancies in zinc oxide and oxygen and neutral/ionized titanium vacancies in titanium dioxide are considered as predominant defect centres responsible for observed ferromagnetism. It is expected that origin of ferromagnetism is a consequence of exchange interactions between localized electron spin moments resulting from point defects.

  7. Gas and liquid phase fuels desulphurization for hydrogen production via reforming processes

    Energy Technology Data Exchange (ETDEWEB)

    Hoguet, Jean-Christophe; Karagiannakis, George P.; Valla, Julia A.; Agrafiotis, Christos C. [Aerosol and Particle Technology Laboratory, CERTH/CPERI, P.O. Box 361, 57001 Thermi, Thessaloniki (Greece); Konstandopoulos, Athanasios G. [Aerosol and Particle Technology Laboratory, CERTH/CPERI, P.O. Box 361, 57001 Thermi, Thessaloniki (Greece); Department of Chemical Engineering, Aristotle University, P.O. Box 1517, 54006 Thessaloniki (Greece)

    2009-06-15

    The present work focuses on the development of efficient desulphurization processes for multi-fuel reformers for hydrogen production. Two processes were studied: liquid hydrocarbon desulphurization and H{sub 2}S removal from reformate gases. For each process, materials with various chemical compositions and microporous structures were synthesized and characterized with respect to their physicochemical properties and desulphurization ability. In the case of liquid phase desulphurization, the adsorption of sulphur compounds contained in diesel fuel under ambient conditions was studied employing as sorbents, zeolite-based materials, i.e. NaY, HY and metal ion-exchanged NaY and HY, as well as a high-surface area activated carbon (AC), for three different diesel fuels with sulphur content varying between 5 and 180 ppmw. Among all sorbents studied, AC showed the best desulphurization performance followed by cerium ion-exchanged HY. The gas phase desulphurization experiments involved the evaluation of zinc-based mixed oxides, synthesized by non-conventional (combustion synthesis) techniques on high steam content reformate gas mixtures. (author)

  8. Graphene via Molecule-Assisted Ultrasound-Induced Liquid-Phase Exfoliation: A Supramolecular Approach

    Science.gov (United States)

    Eredia, Matilde; Ciesielski, Artur; Samorì, Paolo

    2016-12-01

    Graphene is a two-dimensional (2D) material holding unique optical, mechanical, thermal and electrical properties. The combination of these exceptional characteristics makes graphene an ideal model system for fundamental physical and chemical studies as well as technologically ground breaking material for a large range of applications. Graphene can be produced either following a bottom-up or top-down method. The former is based on the formation of covalent networks suitably engineered molecular building blocks undergoing chemical reaction. The latter takes place through the exfoliation of bulk graphite into individual graphene sheets. Among them, ultrasound-induced liquid-phase exfoliation (UILPE) is an appealing method, being very versatile and applicable to different environments and on various substrate types. In this chapter, we describe the recently reported methods to produce graphene via molecule-assisted UILPE of graphite, aiming at the generation of high-quality graphene. In particular, we will focus on the supramolecular approach, which consists in the use of suitably designed organic molecules during the UILPE of graphite. These molecules act as graphene dispersion-stabilizing agents during the exfoliation. This method relying on the joint effect of a solvent and ad hoc molecules to foster the exfoliation of graphite into graphene in liquid environment represents a promising and modular method toward the improvement of the process of UILPE in terms of the concentration and quality of the exfoliated material. Furthermore, exfoliations in aqueous and organic solutions are presented and discussed separately.

  9. Plasma synthesis and liquid-phase surface passivation of brightly luminescent Si nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Mangolini, L. [Department of Mechanical Engineering, University of Minnesota, 111 Church St. SE, Minneapolis, MN 55455 (United States); Jurbergs, D. [InnovaLight, Inc., 3303 Octavius Dr., Suite 104, Santa Clara, CA 95054 (United States); Rogojina, E. [InnovaLight, Inc., 3303 Octavius Dr., Suite 104, Santa Clara, CA 95054 (United States); Kortshagen, U. [Department of Mechanical Engineering, University of Minnesota, 111 Church St. SE, Minneapolis, MN 55455 (United States)]. E-mail: uk@me.umn.edu

    2006-12-15

    While silicon's optical properties are improved at the nanoscale, they also become highly sensitive to the properties of the surfaces and interfaces of silicon nanostructures. For instance, while reported quantum yields for photoluminescence of silicon quantum dots covered by a native oxide are often in the few percent range, quantum yields as high as 30% have been found in quantum dots whose surfaces were passivated by covalently bonded organic molecules. In this paper, we describe an approach that is based on the gas phase synthesis of silicon quantum dots in a nonthermal plasma, and the subsequent organic surface passivation in the liquid phase. Nanocrystals are formed within a few milliseconds with a high mass yield in a nonthermal plasma. Various organic ligands such as octadecene, dodecence, and styrene are grafted onto the nanocrystal surfaces in a reaction known as hydrosilylation. Materials are characterized through transmission electron microscopy, atomic force microscopy, and fluorescence measurements. The particle size distributions are found to be relatively monodisperse and are well controllable through the plasma process parameters. Photoluminescence quantum yields as high as 60-70% have been achieved for particles luminescing in the red range of the visible spectrum.

  10. Preparation of multi-locus DNA probe cocktail by liquid-phase reassociation.

    Science.gov (United States)

    Tamaki, Y; Fukuda, M; Kishida, T; Wang, W

    1995-08-01

    We developed a simple, rapid method for the preparation of a DNA-fingerprinting probe cocktail, and tested its usefulness in paternity testing. Exploiting the property of tandemly repetitive DNA segments to be rapidly renatured after heat denaturation, we enriched restriction fragments of a child's genomic DNA for minisatellites by liquid phase reassociation followed by capture with immobilized streptavidin. We amplified and simultaneously labeled the reassociation product by anchored PCR using a digoxigenin-labeling mixture. Using this probe cocktail, we were able to detect fingerprints of paternity case trios, and the results were corroborated by DNA fingerprinting with a commercially available probe as well as by conventional phenotyping. Our method enables one to prepare a fresh cocktail of probes from the DNA sample under study during the overnight electrophoresis and Southern transfer steps in DNA fingerprinting, and eliminates the need of having an expensive probe of limited shelf life. If one has a practical outlook on DNA fingerprinting and regard it as a preliminary test, one does not have to use a cloned DNA probe. The present study demonstrates that a multi-locus probe cocktail serves such a practical purpose.

  11. Well-posedness of a two-scale model for liquid phase epitaxy with elasticity

    Science.gov (United States)

    Kutter, Michael; Rohde, Christian; Sändig, Anna-Margarete

    2017-07-01

    Epitaxy, a special form of crystal growth, is a technically relevant process for the production of thin films and layers. It can generate microstructures of different morphologies, such as steps, spirals or pyramids. These microstructures are influenced by elastic effects in the epitaxial layer. There are different epitaxial techniques, one being liquid phase epitaxy. Thereby, single particles are deposited out of a supersaturated liquid solution on a substrate where they contribute to the growth process. This article studies a two-scale model including elasticity, introduced in Eck et al. (Eur Phys J Special Topics 177:5-21, 2009) and extended in Eck et al. (2006). It consists of a macroscopic Navier-Stokes system and a macroscopic convection-diffusion equation for the transport of matter in the liquid, and a microscopic problem that combines a phase field approximation of a Burton-Cabrera-Frank model for the evolution of the epitaxial layer, a Stokes system for the fluid flow near the layer and an elasticity system for the elastic deformation of the solid film. Suitable conditions couple the single parts of the model. As the main result, existence and uniqueness of a solution are proven in suitable function spaces. Furthermore, an iterative solving procedure is proposed, which reflects, on the one hand, the strategy of the proof of the main result via fixed point arguments and, on the other hand, can be the basis for a numerical algorithm.

  12. Mathematical modeling of planar and spherical vapor–liquid phase interfaces for multicomponent fluids

    Directory of Open Access Journals (Sweden)

    Celný David

    2016-01-01

    Full Text Available Development of methods for accurate modeling of phase interfaces is important for understanding various natural processes and for applications in technology such as power production and carbon dioxide separation and storage. In particular, prediction of the course of the non-equilibrium phase transition processes requires knowledge of the properties of the strongly curved phase interfaces of microscopic droplets. In our work, we focus on the spherical vapor–liquid phase interfaces for binary mixtures. We developed a robust computational method to determine the density and concentration profiles. The fundamentals of our approach lie in the Cahn-Hilliard gradient theory, allowing to transcribe the functional formulation into a system of ordinary Euler-Langrange equations. This system is then split and modified into a shape suitable for iterative computation. For this task, we combine the Newton-Raphson and the shooting methods providing a good convergence speed. For the thermodynamic roperties, the PC–SAFT equation of state is used. We determine the density and concentration profiles for spherical phase interfaces at various saturation factors for the binary mixture of CO2 and C9H20. The computed concentration profiles allow to the determine the work of formation and other characteristics of the microscopic droplets.

  13. Reaction Kinetics of Ozonation of Trichloroethylene and Benzene in Gas and Liquid Phases

    Institute of Scientific and Technical Information of China (English)

    钟理; KuoChiane-Hai

    2000-01-01

    The kinetics of ozonation reactions of trichloroethylene (TCE) and benzene in gas and liquid phases at 101.3 kPa and 298 K was investigated in this paper. The ozonation of TCE is first order with respect to the ozone concentration and one and half order to TCE in the gas phase with the average rate constant 57.30 (mol·L-1 )-l.5·s-1,and the TCE ozonation in aqueous medium is first order with respect to both ozone and trichloroethylene with the average rate constant 6.30 (mol·L-1)-l·s-1. The ozonation of benzene in the gas phase is first order in ozone but independent of the benzene concentration with the average reaction rate constant 0.0011s-1. The overall kinetics of reaction between ozone and benzene in aqueous solution is found to be first order with one-half order in both ozone and bezene, with the average reaction rate constant 2.67s-1. It is found that the ozonation rate of pallutants is much quicker than that of self-decomposition of ozone in both gas and aqueous phase.

  14. Reaction Kinetics of Ozonation of Trichloroethylene and Benzene in Gas and Liquid Phase

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The kinetics of ozonation reactions oftrichloroethylene (TCE) and benzene in gas and liquid phases at101.3 kPa and 298 K was investigated in this paper. The ozonation ofTCE is first order with respect to the ozone concentration and one andhalf order to TCE in the gas phase with the average rate constant 57.30(mol*L-1)-1.5 *s-1, and the TCE ozonation inaqueous medium is first order with respect to both ozone andtrichloroethylene with the average rate constant 6.30(mol*L-1)-1 *s-1. The ozonation of benzene inthe gas phase is first order in ozone but independent of the benzeneconcentration with the average reaction rate constant 0.0011 s-1.The overall kinetics of reaction between ozone and benzene in aqueoussolution is found to be first order with one-half order in both ozoneand bezene, with the average reaction rate constant 2.67 s-1. Itis found that the ozonation rate of pallutants is much quicker than that ofself-decomposition of ozone in both gas and aqueous phase.

  15. Reduction of Furfural to Furfuryl Alcohol in Liquid Phase over a Biochar-Supported Platinum Catalyst

    Directory of Open Access Journals (Sweden)

    Ariadna Fuente-Hernández

    2017-02-01

    Full Text Available In this work, the liquid phase hydrogenation of furfural has been studied using a biochar-supported platinum catalyst in a batch reactor. Reactions were performed between 170 °C and 320 °C, using 3 wt % and 5 wt % of Pt supported on a maple-based biochar under hydrogen pressure varying from 500 psi to 1500 psi for reaction times between 1 h and 6 h in various solvents. Under all reactive conditions, furfural conversion was significant, whilst under specific conditions furfuryl alcohol (FA was obtained in most cases as the main product showing a selectivity around 80%. Other products as methylfuran (MF, furan, and trace of tetrahydrofuran (THF were detected. Results showed that the most efficient reaction conditions involved a 3% Pt load on biochar and operations for 2 h at 210 °C and 1500 psi using toluene as solvent. When used repetitively, the catalyst showed deactivation although only a slight variation in selectivity toward FA at the optimal experimental conditions was observed.

  16. Investigation of liquid phase axial dispersion in Taylor bubble flow by radiotracer residence time distribution analysis

    Directory of Open Access Journals (Sweden)

    Jin J.H.

    2013-05-01

    Full Text Available A gas-liquid Taylor bubble flow occurs in small diameter channels in which gas bubbles are separated by slugs of pure liquid. This type of flow regime is well suited for solid catalyzed gas-liquid reactors in which the reaction efficiency is a strong function of axial dispersion in the regions of pure liquid. This paper presents an experimental study of liquid phase axial dispersion in a Taylor bubble flow developed in a horizontal tube using high speed photography and radiotracer residence time distribution (RTD analysis. A parametric dependence of axial dispersion on average volume fraction of gas phase was also investigated by varying the relative volumetric flow rates of the two phases. 137mBa produced from a 137Cs/137mBa radionuclide generator was used as radiotracer and measurements were made using the NaI(Tl scintillation detectors. Validation of 137mBa in the form of barium chloride as aqueous phase radiotracer was also carried out. Axial Dispersion Model (ADM was used to simulate the hydrodynamics of the system and the results of the experiment are presented. It was observed that the system is characterized by very high values of Peclet Number (Pe∼102 which reveals an approaching plug type flow. The experimental and model estimated values of mean residence times were observed in agreement with each other.

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

    Science.gov (United States)

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

    2010-01-01

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

  18. Experimental investigation on liquid-phase fabrication techniques for multilayer infrared hollow fiber

    Science.gov (United States)

    Sun, Bang-Shan; Zeng, Xuan; Iwai, Katsumasa; Miyagi, Mitsunobu; Chi, Nan; Shi, Yi-Wei

    2011-07-01

    Infrared hollow fiber with metal and dielectric inner-coatings has found applications in medical and industrial fields. It is a commonly used method to lower the loss by inner-coating multi dielectric layers. In this paper, SiO 2 and AgI were selected to fabricate the multilayer mid-infrared hollow fiber. Liquid-phase coating techniques were experimentally discussed in order to control the film thickness. It is shown that concentration and flow speed of the coating solution are key parameters to modify SiO 2 film thickness. AgI film was obtained by firstly coating a silver layer and then iodinating the silver layer into AgI. SiO 2 and AgI films were deposited orderly on the inner wall of a 0.7-mm bore glass capillary. Both thicknesses for SiO 2 and AgI films were well controlled and optimized according to the theoretical calculation. The measured infrared loss spectrum of SiO 2/AgI/SiO 2/Ag multilayer hollow fiber has a good agreement with the calculated result and shows band gap effect around the wavelength of 5.3 μm.

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

    Directory of Open Access Journals (Sweden)

    Kolovratník Michal

    2015-01-01

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

  20. Synthesis of Acrolein from Glycerol Using FePO4 Catalyst in Liquid Phase Dehydration

    Directory of Open Access Journals (Sweden)

    Akhmad Zainal Abidin

    2016-02-01

    Full Text Available Acrolein is currently produced using propylene from crude oil while its price and scarcity are increasing. A renewable material such as glycerol is an attractive alternative for acrolein production. It can be obtained from crude palm oil (CPO and is a byproduct of biodiesel production. Besides being able to compete economically, glycerol is an environmentally friendly material. The purpose of this study is to synthesize acrolein from glycerol using FePO4 catalyst in liquid phase dehydration. The catalyst was prepared by three different methods: hydrothermal (catalyst A, deposition at Fe/P = 1.15 (catalyst B, and deposition at Fe/P = 1.20 (catalyst C. The experimental reaction temperature was varied at 220, 240 and 260 °C under constant atmospheric pressure. The results showed that catalyst C provided the best yield (91%, followed by catalyst A (90% and catalyst B (82%. The increasing reaction temperature showed a tendency to increase the yield of acrolein, while the presence of oxygen reduced the yield of acrolein and allowed the reaction to produce more side products such as glycerol propanal, acetaldehyde, and propionate. Catalyst reuse without any regeneration resulted in a yield profile of acrolein that continued to decline.

  1. Luminescent transition metal dichalcogenide nanosheets through one-step liquid phase exfoliation

    Science.gov (United States)

    Mar Bernal, M.; Álvarez, Lidia; Giovanelli, Emerson; Arnáiz, Adriana; Ruiz-González, Luisa; Casado, Santiago; Granados, Daniel; Pizarro, Ana M.; Castellanos-Gomez, Andres; Pérez, Emilio M.

    2016-09-01

    Liquid phase exfoliation (LPE) from the bulk is an adequate method for the mass-production of thin nanosheets of transition metal dichalcogenides (TMDCs). However, making suspensions in which the extraordinary properties of mechanically exfoliated TMDCs are observable remains a challenge. We describe a mild LPE method to produce luminescent suspensions of MoS2 and WS2 in N-methylpyrrolidone or isopropanol/water mixtures, without the need for a purification step. The key differences in our experimental procedure compared to previously reported LPE methods are the use of mild bath sonication at controlled temperature and the low initial concentration of the parent TMDC. Spectroscopic and AFM data confirm that an overwhelming majority of the sample is composed of ultrathin nanosheets. HREM data support the formation of the luminescent 2H polytype. The ultrathin nanosheets can be transferred to pure water and cell culture medium. Confocal fluorescence microscopy experiments on MCF-7 breast cancer cells exposed to LPE WS2 show that the cells are viable and the photoluminescence of the nanosheets is detectable.

  2. Thermophysical Properties of Five Industrial Steels in the Solid and Liquid Phase

    Science.gov (United States)

    Wilthan, B.; Schützenhöfer, W.; Pottlacher, G.

    2017-07-01

    The need for characterization of thermophysical properties of steel was addressed in the FFG-Bridge Project 810999 in cooperation with our partner from industry, Böhler Edelstahl GmbH & Co KG. To optimize numerical simulations of production processes such as plastic deformation or remelting, additional and more accurate thermophysical property data were necessary for the group of steels under investigation. With the fast ohmic pulse heating circuit system and a commercial high-temperature Differential Scanning Calorimeter at Graz University of Technology, we were able to measure the temperature-dependent specific electrical resistivity and specific enthalpy for a set of five high alloyed steels: E105, M314, M315, P800, and V320 from room temperature up into the liquid phase. The mechanical properties of those steels make sample preparation an additional challenge. The described experimental approach typically uses electrically conducting wire-shaped specimen with a melting point high enough for the implemented pyrometric temperature measurement. The samples investigated here are too brittle to be drawn as wires and could only be cut into rectangular specimen by Electrical Discharge Machining. Even for those samples all electrical signals and the temperature signal can be recorded with proper alignment of the pyrometer. For each material under investigation, a set of data including chemical composition, solidus and liquidus temperature, enthalpy, electrical resistivity, and thermal diffusivity as a function of temperature will be reported.

  3. Thermodynamic Perturbation Theory for Solid-Liquid Phase Transition of Lennard-Jones Model

    Institute of Scientific and Technical Information of China (English)

    ZHOUShi-Qi; ZHANGXiao-Qi

    2004-01-01

    Both a free volume approach for Helmholtz free energy and a theoretically-based fitted formula for radial distribution function (rdf) of hard sphere solid are employed to describe the Helmholtz free energy of Lennard-Jones solid in the framework of the first order thermodynamic perturbation theory, which also is employed for the uniform Lennard Jones fluid. The dividing of the Lennard-Jones potential follows from the INCA prescription, but the specification of the equivalent hard sphere diameter is determined by a simple iteration procedure devised originally for liquid state, but extended to solid state in the present study. Two hundred shells are used in the rdf to get an accurate perturbation term.The present approach is very accurate for the description of excess Helmholtz free energy of LJ solid, but shows some deviation from the simulation for excess Helmholtz free energy of uniform LJ fluid when the reduced temperature kT/ε is higher then 5. The present approach is satisfactory for description of solid-liquid phase transition of the Lennard-Jones model.

  4. Thermodynamic Perturbation Theory for Solid-Liquid Phase Transition of Lennard-Jones Model

    Institute of Scientific and Technical Information of China (English)

    ZHOU Shi-Qi; ZHANG Xiao-Qi

    2004-01-01

    Both a free volume approach for Helmholtz free energy and a theoretically-based fitted formula for radial distribution function (rdf) of hard sphere solid are employed to describe the Helmholtz free energy of Lennard-Jones solid in the framework of the first order thermodynamic perturbation theory, which also is employed for the uniform LennardJones fluid. The dividing of the Lennard-Jones potential follows from the WCA prescription, but the specification of the equivalent hard sphere diameter is determined by a simple iteration procedure devised originally for liquid state, but extended to solid state in the present study. Two hundred sheiks are used in the rdf to get an accurate perturbation term.The present approach is very accurate for the description of excess Helmholtz free energy of LJ solid, but shows some deviation from the simulation for excess Helmholtz free energy of uniform LJ fluid when the reduced temperature kT/ε is higher then 5. The present approach is satisfactory for description of solid-liquid phase transition of the Lennard-Jones model.

  5. 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.

  6. Quasi-homogeneous oxidation of glycerol by unsupported gold nanoparticles in the liquid phase.

    Science.gov (United States)

    Skrzyńska, Elżbieta; Ftouni, Jamal; Girardon, Jean-Sébastien; Capron, Mickaël; Jalowiecki-Duhamel, Louise; Paul, Jean-François; Dumeignil, Franck

    2012-10-01

    A quasi-homogeneous solution of gold nanoparticles prepared by the Turkevich method was used as an unconventional catalyst in the oxidation of glycerol (GLY) in the liquid phase. The highest obtained conversion was 100 % after 3 h of reaction at 100 °C under an oxygen atmosphere (5 bar). The main products were glyceric, glycolic, formic, tartronic, and oxalic acid with selectivities of 28, 36, 25, 9, and 2 %, respectively. Traces of hydroxypyruvic and acetic acid were also detected (combined selectivities below 1 %). To elucidate the reaction mechanism and specify the role of gold nanoparticles in the oxidation process, a series of experiments under various reaction conditions were carried out. The effect of reaction temperature, oxygen pressure, gold concentration, and GLY/base molar ratio was investigated. All catalytic results were systematically compared to the corresponding noncatalytic base-induced transformations (blank tests). Such an approach allowed us to separate and clarify the respective driving parameters for the transformation of GLY (presence of a base and activity of the gold catalyst). The reaction mechanism comprised a series of oxidation and C-C cleavage reactions, whereas additional oxidation-reduction reactions (of the Cannizzaro type) could also occur in the presence of the base.

  7. Application of advanced sensors to the liquid phase epitaxy (LPE) growth of MCT

    Science.gov (United States)

    Westphal, Glenn H.; Colombo, Luigi; Anderson, Jeff M.

    1994-07-01

    Liquid phase epitaxy (LPE) of (Hg,Cd)Te (MCT) is the technique of choice for the preparation of the materials used for high performance focal plane arrays. Its successful development requires the development of advanced sensors and process controls. We detail here progress on the application of four sensor technologies to the LPE process for growth of MCT layers from Te rich melts on CdZnTe substrates. These include: (1) electron beam microprobe/wavelength dispersive x-ray analysis (WDX) for the rapid measurement of film composition immediately after growth; (2) an RTD based precision temperature control system that controls the melt temperature to better than +/- 0.005 degree(s)C and the Hg reservoir temperature to better than +/- 0.020 degree(s)C; (3) UV/visible optical absorption spectroscopy for the determination of the Hg partial pressure over the melt; and (4) CCD imaging for the detection of the liquid temperature of the LPE growth solution. The impact of each of the sensors on process yield is discussed. The application of the CCD camera to Hg rich high pressure LPE growth is also briefly mentioned.

  8. Liquid phase sintered SiC. Processing and transformation controlled microstructure tailoring

    Directory of Open Access Journals (Sweden)

    V.A. Izhevskyi

    2000-10-01

    Full Text Available Microstructure development and phase formation processes during sintering of silicon carbide based materials with AlN-Y2O3, AlN-Yb2O3, and AlN-La2O3 sintering additives were investigated. Densification of the materials occurred by liquid-phase sintering mechanism. Proportion of alpha- and beta-SiC powders in the initial mixtures was a variable parameter, while the molar ratio of AlN/RE2O3, and the total amount of additives (10 vol. % were kept constant. Shrinkage behavior during sintering in interrelation with the starting composition of the material and the sintering atmosphere was investigated by high temperature dilatometry. Kinetics of b-SiC to a-SiC phase transformation during post-sintering heat treatment at temperatures 1900-1950 °C was studied, the degree of phase transformation being determined by quantitative x-ray analysis using internal standard technique. Evolution of microstructure resulting from beta-SiC to alpha-SiC transformation was followed up by scanning electron microscopy on polished and chemically etched samples. Transformation-controlled grain growth mechanism similar to the one observed for silicon nitride based ceramics was established. Possibility of in-situ platelet reinforced dense SiC-based ceramics fabrication with improved mechanical properties by means of sintering was shown.

  9. Weakly doped InP layers prepared by liquid phase epitaxy using a modulated cooling rate

    Science.gov (United States)

    Krukovskyi, R.; Mykhashchuk, Y.; Kost, Y.; Krukovskyi, S.; Saldan, I.

    2017-04-01

    Epitaxial structures based on InP are widely used to manufacture a number of devices such as microwave transistors, light-emitting diodes, lasers and Gunn diodes. However, their temporary instability caused by heterogeneity of resistivity along the layer thickness and the influence of various external or internal factors prompts the need for the development of a new reliable technology for their preparation. Weak doping by Yb, Al and Sn together with modulation of the cooling rate applied to prepare InP epitaxial layers is suggested to be adopted within the liquid phase epitaxy (LPE) method. The experimental results confirm the optimized conditions created to get a uniform electron concentration in the active n-InP layer. A sharp profile of electron concentration in the n+-InP(substrate)/n-InP/n+-InP epitaxial structure was observed experimentally at the proposed modulated cooling rate of 0.3 °С-1.5 °С min-1. The proposed technological method can be used to control the electrical and physical properties of InP epitaxial layers to be used in Gunn diodes.

  10. Fuel and power coproduction: The Liquid Phase Methanol (LPMEOH{trademark}) process demonstration at Kingsport

    Energy Technology Data Exchange (ETDEWEB)

    Drown, D.P.; Brown, W.R.; Heydorn, E.C.; Moore, R.B.; Schaub, E.S.; Brown, D.M.; Jones, W.C.; Kornosky, R.M.

    1997-12-31

    The Liquid Phase Methanol (LPMEOH{trademark}) process uses a slurry bubble column reactor to convert syngas (primarily a mixture of carbon monoxide and hydrogen) to methanol. Because of its superior heat management, the process is able to be designed to directly handle the carbon monoxide (CO)-rich syngas characteristic of the gasification of coal, petroleum coke, residual oil, wastes, or of other hydrocarbon feedstocks. When added to an integrated gasification combined cycle (IGCC) power plant, the LPMEOH{trademark} process converts a portion of the CO-rich syngas produced by the gasifier to methanol, and the remainder of the unconverted gas is used to fuel the gas turbine combined-cycle power plant. The LPMEOH{trademark} process has the flexibility to operate in a daily electricity demand load-following manner. Coproduction of power and methanol via IGCC and the LPMEOH{trademark} process provides opportunities for energy storage for electrical demand peak shaving, clean fuel for export, and/or chemical methanol sales.

  11. 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.

  12. Transition metal doping of GaSe implemented with low temperature liquid phase growth

    Science.gov (United States)

    Lei, Nuo; Sato, Youhei; Tanabe, Tadao; Maeda, Kensaku; Oyama, Yutaka

    2017-02-01

    Our group works on improving the conversion efficiencies of terahertz (THz) wave generation using GaSe crystals. The operating principle is based on difference frequency generation (DFG) which has the advantages such as high output power, a single tunable frequency, and room temperature operation. In this study, GaSe crystals were grown by the temperature difference method under controlled vapor pressure (TDM-CVP). It is a liquid phase growth method with temperature 300 °C lower than that of the Bridgman method. Using this method, the point defects concentration is decreased and the polytype can be controlled. The transition metal Ti was used to dope the GaSe in order to suppress free carrier absorption in the low frequency THz region. As a result, a deep acceptor level of 38 meV was confirmed as being formed in GaSe with 1.4 at% Ti doping. Compared with undoped GaSe, a decrease in carrier concentration ( 1014 cm-3) at room temperature was also confirmed. THz wave transmittance measurements reveal the tendency for the absorption coefficient to increase as the amount of dopant is increased. It is expected that there is an optimum amount of dopant.

  13. Industrialization of technology of continuous liquid phase separation. Renzoku ekiso bunri gijutsu no kogyoka

    Energy Technology Data Exchange (ETDEWEB)

    Nakaishi, H. (JGC Corp., Tokyo (Japan))

    1994-01-05

    As one example of process technology industrialized in 1960s, a continuous process by liquid phase adsorption is introduced, that was developed by an American enterprise for petroleum refining. The background of development is described in details and elements for its success are explained as well as the impact. The motive for development was to separate n-paraffin from oil with molecular sieves in order to raise octane values of gasoline. However, the scene realized in industrialization was in the separation of n-paraffin from kerosene to get raw materials for synthetic detergents. Although literature on gas phase adsorption was well documented at that time, liquid adsorption that was an untrodden field was decided to be explored in consideration of problems involved in high temperature required for gas phase sdsorption. Taking theoretical validity of a moving bed system into consideration, a pseudo-moving bed system, wherein adsorption beds are still and the take-in/-out position of liquid moves with time lapse, was developed for the sake of limited mechanical strength of adsorbent (zeolite)and biased flow caused by moving layers. Use of mathematical models as probes for phenomena of chemical engineering and for analysis of process performance by computers contributed greatly to the success. 3 refs., 1 fig.

  14. 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.  

  15. Catalyst activity maintenance study for the liquid phase dimethyl ether process

    Energy Technology Data Exchange (ETDEWEB)

    Peng, X.D.; Toseland, B.A.; Underwood, R.P. [Air Products and Chemicals, Inc., Allentown, PA (United States)

    1995-12-31

    The co-production of dimethyl ether (DME) and methanol from syngas is a process of considerable commercial attractiveness. DME coproduction can double the productivity of a LPMEOH process when using coal-derived syngas. This in itself may offer chemical producers and power companies increased flexibility and more profitable operation. DME is also known as a clean burning liquid fuel; Amoco and Haldor-Topsoe have recently announced the use of DME as an alternative diesel fuel. Moreover, DME can be an interesting intermediate in the production of chemicals such as olefins and vinyl acetate. The current APCl liquid phase dimethyl ether (LPDME) process utilizes a physical mixture of a commercial methanol synthesis catalyst and a dehydration catalyst (e.g., {gamma}-alumina). While this arrangement provides a synergy that results in much higher syngas conversion per pass compared to the methanol-only process, the stability of the catalyst system suffers. The present project is aimed at reducing catalyst deactivation both by understanding the cause(s) of catalyst deactivation and by developing modified catalyst systems. This paper describes the current understanding of the deactivation mechanism.

  16. Thermodynamic modeling of liquid–liquid phase change solvents for CO2 capture

    DEFF Research Database (Denmark)

    Waseem Arshad, Muhammad; von Solms, Nicolas; Thomsen, Kaj

    2016-01-01

    A thermodynamic model based on Extended UNIQUAC framework has been developed in this work for the de-mixing liquid–liquid phase change solvents, DEEA (2-(diethylamino)ethanol) and MAPA (3-(methylamino)propylamine). Parameter estimation was performed for two ternary systems, H2O-DEEA-CO2 and H2O-MAPA......-CO2, and a quaternary system, H2O-DEEA-MAPA-CO2 (phase change system), by using different types of experimental data (equilibrium and thermal) consisting of pure amine vapor pressure, vapor-liquid equilibrium, solid-liquid equilibrium, liquid–liquid equilibrium, excess enthalpy, and heat of absorption...... are valid in the temperature range from −25 to 200 °C, CO2 partial pressure from 0 to 945 kPa, and concentration of DEEA, MAPA, and CO2 up to 131, 23, and 33 mol(kg H2O)−1, respectively. The model calculated speciation are also presented for the studied systems. The model developed in this work can be used...

  17. 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.

  18. 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.

  19. The solid-liquid phase diagrams of binary mixtures of consecutive, even saturated fatty acids.

    Science.gov (United States)

    Costa, Mariana C; Sardo, Mariana; Rolemberg, Marlus P; Coutinho, João A P; Meirelles, Antonio J A; Ribeiro-Claro, Paulo; Krähenbühl, M A

    2009-08-01

    For the first time, the solid-liquid phase diagrams of five binary mixtures of saturated fatty acids are here presented. These mixtures are formed of caprylic acid (C(8:0))+capric acid (C(10:0)), capric acid (C(10:0))+lauric acid (C(12:0)), lauric acid (C(12:0))+myristic acid (C(14:0)), myristic acid (C(14:0))+palmitic acid (C(16:0)) and palmitic acid (C(16:0))+stearic acid (C(18:0)). The information used in these phase diagrams was obtained by differential scanning calorimetry (DSC), X-ray diffraction (XRD), FT-Raman spectrometry and polarized light microscopy, aiming at a complete understanding of the phase diagrams of the fatty acid mixtures. All of the phase diagrams reported here presented the same global behavior and it was shown that this was far more complex than previously imagined. They presented not only peritectic and eutectic reactions, but also metatectic reactions, due to solid-solid phase transitions common in fatty acids and regions of solid solution not previously reported. This work contributes to the elucidation of the phase behavior of these important biochemical molecules, with implications in various industrial applications.

  20. Liquid phase adsorption behavior of inulin-type fructan onto activated charcoal.

    Science.gov (United States)

    Li, Kecheng; Liu, Song; Xing, Ronge; Yu, Huahua; Qin, Yukun; Li, Pengcheng

    2015-05-20

    This study describes liquid phase adsorption characteristics of inulin-type fructan onto activated charcoal. Batch mode experiments were conducted to study the effects of pH, contact time, temperature and initial concentration of inulin. Nearly neutral solution (pH 6-8) was favorable to the adsorption and the equilibrium was attained after 40 min with the maximum adsorption Qmax 0.182 g/g (adsorbate/adsorbent) at 298 K. The experimental data analysis indicated that the adsorption process fitted well with the pseudo-second-order kinetic model (R(2) = 1) and Langmuir isotherms model (R(2) > 0.99). Thermodynamic parameters revealed that the adsorption process was spontaneous and exothermic with a physical nature. Inulin desorption could reach 95.9% using 50% ethanol solution and activated charcoal could be reused without significant losses in adsorption capacity. These results are of practical significance for the application of activated charcoal in the production and purification of inulin-type fructan.

  1. Liquid phase surface alloying of AZ91D magnesium alloy with Al and Ni powders

    Energy Technology Data Exchange (ETDEWEB)

    Elahi, Mohammad Reza, E-mail: m.r_elahi@alumni.ut.ac.ir [School of Metallurgy and Materials, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Sohi, Mahmoud Heydarzadeh; Safaei, Abdolghayoom [School of Metallurgy and Materials, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)

    2012-05-15

    In this paper, liquid phase surface alloying of AZ91D magnesium alloy was carried out by pre-placing of Al and Ni powder mixture and subsequent tungsten inert gas (TIG) melting process. The effects of TIG processing parameters on both microstructures and resulting hardness were investigated. Microstructures of alloyed layers were studied by optical microscope, and scanning electron microscope equipped with energy dispersive X-ray spectroscopy (EDS) analyzer, and the phases were identified by X-ray diffraction analysis. The microhardness of the surface alloyed layer was also measured. The surface hardness was increased from 80 HV{sub 0.1} for AZ91D magnesium alloy to as high as 162 HV{sub 0.1} for alloyed sample due to the formation of Mg{sub 17}Al{sub 12} and AlNi{sub 3} intermetallic compounds in the alloyed region and structural refinement. Hardness improvement reduced the wear rate of the surface alloyed layer to almost half of that of the untreated substrate.

  2. Nano-structured gemini-based supramolecular solvent for the microextraction of cyhalothrin and fenvalerate.

    Science.gov (United States)

    Feizi, Neda; Yamini, Yadollah; Moradi, Morteza; Ebrahimpour, Behnam

    2016-09-01

    A novel supramolecular solvent-based microextraction followed by high-performance liquid chromatography with ultraviolet detection method has been developed for the extraction and determination of two pyrethroid analytes, cyhalothrin and fenvalerate, in water and soil samples. The liquid-liquid-phase separation of surfactants has been used in analytical extraction. The surfactant-rich phase is a nano-structured liquid, recently named as a supramolecular solvent, generated from the amphiphiles. The alkyl carboxylic acid based supramolecular solvents were introduced before. Coacervates made up of gemini surfactant, consisting of two amphiphilic moieties, were first used as solvent. The effective parameters on extraction (i.e., type of organic solvent, the amount of surfactant and volume of tetrahydrofuran, sample solution pH, salt addition, ultrasonic and centrifugation time) were investigated and optimized. Under the optimum conditions, preconcentration factors of 110 and 145 were obtained for the analytes. The linearity was 0.5-200.0 μg/L with the correlation of determination of (R(2) ) ≥ 0.9984. The limit of detection of the method was (S/N = 3) 0.2 μg/L, and precisions in the range of 6.3-10.3% (RSDs, n = 5) were obtained. This method has been successfully applied to analyze real samples, and good recoveries in the range of 101.2-108.8% were obtained.

  3. Bacterial diversity of a consortium degrading high-molecular-weight polycyclic aromatic hydrocarbons in a two-liquid phase biosystem.

    Science.gov (United States)

    Lafortune, Isabelle; Juteau, Pierre; Déziel, Eric; Lépine, François; Beaudet, Réjean; Villemur, Richard

    2009-04-01

    High-molecular-weight (HMW) polycyclic aromatic hydrocarbons (PAHs) are pollutants that persist in the environment due to their low solubility in water and their sequestration by soil and sediments. Although several PAH-degrading bacterial species have been isolated, it is not expected that a single isolate would exhibit the ability to degrade completely all PAHs. A consortium composed of different microorganisms can better achieve this. Two-liquid phase (TLP) culture systems have been developed to increase the bioavailability of poorly soluble substrates for uptake and biodegradation by microorganisms. By combining a silicone oil-water TLP system with a microbial consortium capable of degrading HMW PAHs, we previously developed a highly efficient PAH-degrading system. In this report, we characterized the bacterial diversity of the consortium with a combination of culture-dependent and culture-independent methods. Polymerase chain reaction (PCR) of part of the 16S ribosomal RNA gene (rDNA) sequences combined with denaturing gradient gel electrophoresis was used to monitor the bacterial population changes during PAH degradation of the consortium when pyrene, chrysene, and benzo[a]pyrene were provided together or separately in the TLP cultures. No substantial changes in bacterial profiles occurred during biodegradation of pyrene and chrysene in these cultures. However, the addition of the low-molecular-weight PAHs phenanthrene or naphthalene in the system favored one bacterial species related to Sphingobium yanoikuyae. Eleven bacterial strains were isolated from the consortium but, interestingly, only one-IAFILS9 affiliated to Novosphingobium pentaromativorans-was capable of growing on pyrene and chrysene as sole source of carbon. A 16S rDNA library was derived from the consortium to identify noncultured bacteria. Among 86 clones screened, 20 were affiliated to different bacterial species-genera. Only three strains were represented in the screened clones. Eighty

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

    Energy Technology Data Exchange (ETDEWEB)

    None

    1998-12-21

    he Liquid Phase Methanol (LPMEOW) Demonstration Project at Kingsport Tennessee, is a $213.7 million cooperative agreement between the U.S. Department of Energy (DOE) and Air Products Liquid Phase Conversion Company, L.P. (the Partnership) to produce methanol from coal-derived synthesis gas (syngas). Air Products and Chemicals, Inc. (Air Products) and Eastman Chemical Company (Eastman) formed the Partnership to execute the Demonstration Project. The LPMEOEP Process Demonstration Unit was built at a site located at the Eastman coal-to-chemicals complex in Kingsport. The LPMEOHW Demonstration Facility completed its first year of operation on 02 April 1998. The LPMEOW Demonstration Facility also completed the longest continuous operating run (65 days) on 21 April 1998. Catalyst activity, as defined by the ratio of the rate constant at any point in time to the rate constant for freshly reduced catalyst (as determined in the laboratory autoclave), was monitored throughout the reporting period. During a six-week test at a reactor temperature of 225oC and Balanced Gas flowrate of 700 KSCFH, the rate of decline in catalyst activity was steady at 0.29-0.36% per day. During a second one-month test at a reactor temperature of 220oC and a Balanced Gas flowrate of 550-600 KSCFH, the rate of decline in catalyst activity was 0.4% per day, which matched the pefiorrnance at 225"C, as well as the 4-month proof-of-concept run at the LaPorte AFDU in 1988/89. Beginning on 08 May 1998, the LPMEOW Reactor temperature was increased to 235oC, which was the operating temperature tier the December 1997 restart with the fresh charge of catalyst (50'Yo of design loading). The flowrate of the primary syngas feed stream (Balanced Gas) was also increased to 700-750 KSCFH. During two stable operating periods between 08 May and 09 June 1998, the average catalyst deactivation rate was 0.8% per day. Due to the scatter of the statistical analysis of the results, this test was extended to better

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

    Energy Technology Data Exchange (ETDEWEB)

    None

    1998-12-21

    The Liquid Phase Methanol (LPMEOW) Demonstration Project at Kingsport Tennessee, is a $213.7 million cooperative agreement between the U.S. Department of Energy (DOE) and Air Products Liquid Phase Conversion Company, L.P. (the Partnership) to produce methanol from coal-derived synthesis gas (syngas). Air Products and Chemicals, Inc. (Air Products) and Eastman Chemical Company (Eastman) formed the Partnership to execute the Demonstration Project. The LPMEOW Process Demonstration Unit was built at a site located at the Eastman complex in Kingsport. During this quarter, initial planning and procurement work began on the seven project sites which have been accepted for participation in the off-site, methanol product-use test plan. Two of the projects have begun pre-testing of equipment and three other projects have commenced with equipment procurement, Methanol produced from carbon monoxide (CO)- rich syngas at the Alternative Fuels Development Unit (AFDU) in LaPorte, TX has been shipped to four of the project sites in anticipation of the start of testing during the first quarter of calendar year 1998. Catalyst activity, as defined by the ratio of the rate constant at any point in time to the rate constant for a freshly reduced catalyst (as determined in the laboratory autoclave), continued to decline more rapidly than expected. In response to concentrations of arsenic and sulfbr detected on catalyst samples from the LPMEOW Reactor, Eastman replaced both the arsine- and sulfiwremoval material in the Eastman guard bed which treats the primary syngas feed stream (&danced Gas) prior to its introduction into both the Eastman fixed-bed methanol plant and the LPMEOWM Demonstration Unit. After restarting the demonstration unit, the catalyst deactivation rate remained essentially unchanged. Parallel testing in the laboratory using arsine-doped, and subsequently arsine- and SuIfi-doped syngas, ako ftiIed to prove that arsine was responsible for the higher-than-expected rate of

  6. 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.

  7. Thermophysical Properties of a Chromium Nickel Molybdenum Steel in the Solid and Liquid Phases

    Science.gov (United States)

    Wilthan, B.; Reschab, H.; Tanzer, R.; Schützenhöfer, W.; Pottlacher, Gernot

    2008-02-01

    Numerical simulation of vacuum arc re-melting, pressurized or protective electro-slag re-melting, and ingot casting have become quite important in the metal industry. However, a major drawback of these simulation techniques is the lack of accurate thermophysical properties for temperatures above 1,500 K. Heat capacity, heat of fusion, density, and thermal conductivity are important input parameters for the heat transfer equation. Since, direct measurements of thermal conductivity of alloys in the liquid state are almost impossible, its estimation from electrical conductivity using the Wiedemann Franz law is very useful. The afore-mentioned thermophysical properties of several steels are investigated within the context of an ongoing project. Here, we present a full set of thermophysical data for the chromium nickel molybdenum steel meeting the standard DIN 1.4435 (X2CrNiMo18-14-3); these values will be used by our partner to simulate various re-melting and solidification processes. Wire-shaped samples of the steel are resistively volume-heated, as part of a fast capacitor discharge circuit. Time-resolved measurements with sub-μs resolution of current through the specimen are performed with a Pearson probe. The voltage drop across the specimen is measured with knife-edge contacts and ohmic voltage dividers, the temperature of the sample with a pyrometer, and the volumetric expansion of the wire with a fast acting CCD camera. These measurements enable the heat of fusion, the heat capacity, and the electrical resistivity to be determined as a function of temperature in the solid and liquid phases. The thermal conductivity and thermal diffusivity are estimated via the Wiedemann Franz law.

  8. Bimetallic Au-decorated Pd catalyst for the liquid phase hydrodechlorination of 2,4-dichlorophenol

    Science.gov (United States)

    Zhou, Juan; Chen, Huan; Chen, Quanyuan; Huang, Zhaolu

    2016-11-01

    Monometallic and bimetallic Pd-Au catalysts supported on multi-walled carbon nanotubes (CNTs) with varied Au cooperation amounts were prepared using the complexing-reduction method in the presence of tetrahydrofuran (THF). The liquid phase catalytic hydrodechlorination (HDC) of 2,4-dichlorophenol (2,4-DCP) was investigated over these bimetallic catalysts. The catalysts were characterized by N2 adsorption-desorption isotherms, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and H2 chemisorption. Characterization results showed that the co-reduction of Pd and Au mainly formed alloy-like structure. The bimetallic catalysts had smaller metal particles and larger numbers of exposed active site than that of monometallic catalysts. In addition, compared with Pd(1.7)/CNTs and Au(0.4)/CNTs, the binding energies of Pd 3d5/2 shifted to higher positions while that of Au 4f7/2 had negative shifts in the Pd-Au bimetallic catalysts, which can be ascribed to the electrons transferred from metal Pd to Au and the cationization of Pd particles was enhanced. Accordingly, the bimetallic Pd-Au particles with different Au contents in the catalysts exhibited varied synergistic effects for the catalytic HDC of 2,4-DCP, with Pd(1.8)Au(0.4)/CNTs having the highest catalytic activity. For the bimetallic catalysts, a disproportional increase of turnover frequency (TOF) was observed with increasing Au content due to the enhanced cationization of Pd particles. Moreover, the dechlorination of 2,4-DCP over the supported monometallic and bimetallic catalysts proceeded via both the stepwise and concerted pathway, and the concerted pathway became predominant with Au decoration amount in the catalyst.

  9. Liquid phase catalytic hydrodebromination of tetrabromobisphenol A on supported Pd catalysts

    Science.gov (United States)

    Wu, Ke; Zheng, Mengjia; Han, Yuxiang; Xu, Zhaoyi; Zheng, Shourong

    2016-07-01

    Tetrabromobisphenol A (TBBPA) is a widely used brominated flame retardant and reductive debromination is an effective method for the abatement of TBBPA pollution. In this study, Pd catalysts supported on TiO2, CeO2, Al2O3 and SiO2 were prepared by the impregnation (the resulting catalyst denoted as im-Pd/support), deposition-precipitation (the resulting catalyst denoted as dp-Pd/support), and photo-deposition (the resulting catalyst denoted as pd-Pd/support) methods. The catalysts were characterized by N2 adsorption-desorption isotherm, X-ray diffraction, transmission electron microscopy, measurement of zeta potential, CO chemisorption, and X-ray photoelectron spectroscopy. The results showed that at an identical Pd loading amount (2.0 wt.%) Pd particle size in dp-Pd/TiO2 was much smaller than those in im-Pd/TiO2 and pd-Pd/TiO2. Pd particle size of the dp-Pd/TiO2 catalyst increased with Pd loading amount. Additionally, Pd particles in the dp-Pd/TiO2 catalysts were positively charged due to the strong metal-support interaction, whereas the cationization effect was gradually attenuated with the increase of Pd loading amount. For the liquid phase catalytic hydrodebromination (HDB) of TBBPA, tri-bromobisphenol A (tri-BBPA), di-bromobisphenol A (di-BBPA), and mono-bromobisphenol A (mono-BBPA) were identified as the intermediate products, indicative of a stepwise debromination process. The catalytic HDB of TBBPA followed the Langmuir-Hinshelwood model, reflecting an adsorption enhanced catalysis mechanism. At an identical Pd loading amount, the Pd catalyst supported on TiO2 exhibited a much higher catalytic activity than those on other supports. Furthermore, dp-Pd/TiO2 was found to be more active than im-Pd/TiO2 and pd-Pd/TiO2.

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

    Science.gov (United States)

    Santos, Bjorn Sanchez

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

  11. Development of refractory armored silicon carbide by infrared transient liquid phase processing

    Science.gov (United States)

    Hinoki, Tatsuya; Snead, Lance L.; Blue, Craig A.

    2005-12-01

    Tungsten (W) and molybdenum (Mo) were coated on silicon carbide (SiC) for use as a refractory armor using a high power plasma arc lamp at powers up to 23.5 MW/m 2 in an argon flow environment. Both tungsten powder and molybdenum powder melted and formed coating layers on silicon carbide within a few seconds. The effect of substrate pre-treatment (vapor deposition of titanium (Ti) and tungsten, and annealing) and sample heating conditions on microstructure of the coating and coating/substrate interface were investigated. The microstructure was observed by scanning electron microscopy (SEM) and optical microscopy (OM). The mechanical properties of the coated materials were evaluated by four-point flexural tests. A strong tungsten coating was successfully applied to the silicon carbide substrate. Tungsten vapor deposition and pre-heating at 5.2 MW/m 2 made for a refractory layer containing no cracks propagating into the silicon carbide substrate. The tungsten coating was formed without the thick reaction layer. For this study, small tungsten carbide grains were observed adjacent to the interface in all conditions. In addition, relatively large, widely scattered tungsten carbide grains and a eutectic structure of tungsten and silicon were observed through the thickness in the coatings formed at lower powers and longer heating times. The strength of the silicon carbide substrate was somewhat decreased as a result of the processing. Vapor deposition of tungsten prior to powder coating helped prevent this degradation. In contrast, molybdenum coating was more challenging than tungsten coating due to the larger coefficient of thermal expansion (CTE) mismatch as compared to tungsten and silicon carbide. From this work it is concluded that refractory armoring of silicon carbide by Infrared Transient Liquid Phase Processing is possible. The tungsten armored silicon carbide samples proved uniform, strong, and capable of withstanding thermal fatigue testing.

  12. Double multiple-relaxation-time lattice Boltzmann model for solid-liquid phase change with natural convection in porous media

    Science.gov (United States)

    Liu, Qing; He, Ya-Ling

    2015-11-01

    In this paper, a double multiple-relaxation-time lattice Boltzmann model is developed for simulating transient solid-liquid phase change problems in porous media at the representative elementary volume scale. The model uses two different multiple-relaxation-time lattice Boltzmann equations, one for the flow field and the other for the temperature field with nonlinear latent heat source term. The model is based on the generalized non-Darcy formulation, and the solid-liquid interface is traced through the liquid fraction which is determined by the enthalpy-based method. The present model is validated by numerical simulations of conduction melting in a semi-infinite space, solidification in a semi-infinite corner, and convection melting in a square cavity filled with porous media. The numerical results demonstrate the efficiency and accuracy of the present model for simulating transient solid-liquid phase change problems in porous media.

  13. Magnetic Properties of Liquid-Phase Sintered CoFe2O4 for Application in Magnetoelastic and Magnetoelectric Transducers

    Science.gov (United States)

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

    2012-01-01

    Cobalt ferrite is a ferrimagnetic magnetostrictive ceramic that has potential application in magnetoelastic and magnetoelectric transducers. In this work, CoFe2O4 was obtained using a conventional ceramic method and Bi2O3 was used as additive in order to obtain liquid-phase sintered samples. Bi2O3 was added to the ferrite in amounts ranging from 0.25 mol% to 0.45 mol% and samples were sintered at 900 °C and 950 °C. It was observed the presence of Bi-containing particles in the microstructure of the sintered samples and the magnetostriction results indicated microstructural anisotropy. It was verified that it is possible to get dense cobalt ferrites, liquid-phase sintered, with relative densities higher than 90% and with magnetostriction values very close to samples sintered without additives. PMID:23112589

  14. A liquid phase based C. elegans behavioral analysis system identifies motor activity loss in a nematode Parkinson's disease model.

    Science.gov (United States)

    Zheng, Maohua; Gorelenkova, Olga; Yang, Jiong; Feng, Zhaoyang

    2012-03-15

    Motor activity of Caenorhabditis elegans is widely used to study the mechanisms ranging from basic neuronal functions to human neurodegenerative diseases. It may also serve as a paradigm to screen for potential therapeutic reagents treating these diseases. Here, we developed an automated, 96-well plate and liquid phase based system that quantifies nematode motor activity in real time. Using this system, we identified an adult-onset, ageing-associated motor activity loss in a transgenic nematode line expressing human pathogenic G2019S mutant LRRK2 (leucine-rich repeat kinase 2), the leading genetic cause of Parkinson's disease characterized by dopaminergic neurodegeneration associated motor deficient mainly in elder citizens. Thus, our system may be used as a platform to screen for potential therapeutic drugs treating Parkinson's disease. It can also be used to monitor motor activity of nematodes in liquid phase at similar scenario. Copyright © 2011 Elsevier B.V. All rights reserved.

  15. Enzymatic catalysis in heterogenous mixtures of substrates: The role of the liquid phase and the effects of "Adjuvants".

    Science.gov (United States)

    López-Fandiño, R; Gill, I; Vulfson, E N

    1994-05-01

    The physicochemical mechanism of protease-catalyzed peptide synthesis in heterogenous etuectic mixtures of substrates has been examined by a combination of microscopic techniques. Using a number of model reactions of dipeptide amide synthesis, it was determined that liquid phase catalysis was mostly, if not exclusively, responsible for the observed conversion of substrates. Furthermore, the formation of liquid or semiliquid eutectics was an important requirement for the occurrence of those reactions where both substrates were solids in the pure state. The addition of small quantities of hydrophilic solvents (adjuvants) often resulted in significat improvements in the rates and yields of the reactions. This was due to the ability of these adjuvants to promote the formation of eutectics, thereby increasing the proportion, as well as affecting the composition the properties, as well as affecting the composition and properties of the liquid phase. (c) 1994 John Wiley & Sons, Inc.

  16. Gas-phase adsorption in dealuminated natural clinoptilolite and liquid-phase adsorption in commercial DAY zeolite and modified ammonium Y zeolite

    Science.gov (United States)

    Costa Hernandez, Alba Nydia

    The adsorption of Carbon Dioxide (CO2) is a very important tool for the material characterization. On the other hand, in separation and recovery technology, the adsorption of the CO2 is important to reduce the concentration of this gas considered as one of the greenhouse gases. Natural zeolites, particularly clinoptilolite, are widely applied to eliminate some pollutants from the environment. One of the goals of this research is to study the structure, composition and morphology of one natural clinoptilolite dealuminated with ammonium hexafluorosilicate (AHFi) and with orthophosphoric acid (H3PO4). Each modified sample was characterized using X-ray Diffraction (XRD), Carbon Dioxide adsorption at 0° C, Thermogravimetric Analysis (TGA), and Scanning Electron Microscopy with Energy Dispersive X-Ray Analysis (SEM-EDAX). In addition, the surface chemistry of the modified clinoptilolites was analyzed with Diffuse Reflectance Fourier Transform Infrared Spectroscopy (DRIFTS). The adsorption measurements were also used to study of the interaction of CO2 molecule within the adsorption space of these modified clinoptilolites. It was concluded that one of the modified clinoptilolites, (CSW-HFSi-0.1M), showed a great quality as adsorbent and as catalytic comparable to commercial synthetic zeolites. As far as we know, the modification of clinoptilolite with HFSi to improve their adsorption properties had not been previously attempted. In the second part of this dissertation, the dynamic adsorption of three isomers of nitrophenols using as adsorbent a commercial DAY zeolite was investigated. Also, the dynamic adsorption of methanol in a less hydrophobic zeolite, Ammonium Y Zeolite was investigated. The obtained breakthrough curves showed that the commercial DAY zeolite could be a suitable adsorbent to the liquid-phase adsorption of the phenolic compounds. Notwithstanding the modified ammonium Y zeolite had a low Si/Al ratio (less hydrophobic) than commercial DAY zeolite; this

  17. 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.

  18. 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

  19. Extraction of carbamate pesticides in fruit samples by graphene reinforced hollow fibre liquid microextraction followed by high performance liquid chromatographic detection.

    Science.gov (United States)

    Ma, Xiaoxing; Wang, Juntao; Wu, Qiuhua; Wang, Chun; Wang, Zhi

    2014-08-15

    Graphene reinforced hollow fibre liquid phase microextraction combined with high performance liquid chromatography-diode array detection was developed for the determination of some carbamate pesticides (metolcarb, carbaryl, isoprocarb, and diethofencarb) in fruit samples. The main parameters that affect the extraction efficiency for the carbamates were investigated. Under the optimum conditions, a good linearity was observed in the range of 1.0-100.0 ng g(-1) for carbaryl and 3.0-100.0 ng g(-1) for the other three analytes, with the correlation coefficients (r) of 0.9965-0.9993. The limits of detection of the method ranged from 0.2 to 1.0 ng g(-1). The relative standard deviations were in the range from 6.2% to 7.8%. The results indicated that the developed method is sensitive and efficient for the determination of the carbamate pesticides in fruit samples. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. 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%.

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

    Institute of Scientific and Technical Information of China (English)

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

    2014-01-01

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

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

    Science.gov (United States)

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

    2014-10-01

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

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

    Science.gov (United States)

    Butts, Daniel A.

    The research work presented here discusses transient liquid phase (TLP) bonding of a current (i.e. third) generation gamma-TiAl alloy known as Gamma Met PX (GMPX). Effective implementation of GMPX in service is likely to require fabrication of complicated geometries for which a high performance metallurgical joining technique must be developed. Although a number of joining processes have been investigated, all have significant disadvantages that limit their ability to achieve sound joints. TLP bonding has proved to be a successful method of producing joints with microstructures and compositions similar to that of the bulk substrates. Hence, bonds with parent-like mechanical and oxidation properties are possible. The interlayer and bonding conditions employed for joining of GMPX were based on successful wide-gap TLP joining trials of an earlier generation cast gamma-TiAl alloy with a composition of Ti-48Al-2Cr-2Nb in atomic percent (abbreviated here to 48-2-2). A composite interlayer consisting of a 6:1 weight ratio (7 vol.% copper) of gas atomized 48-2-2 powders (-270 mesh) and pure copper powders (-325 mesh) was employed. When applied to GMPX, these interlayer ratio and bonding conditions produced undesirable microstructures and poor mechanical performance in as-bonded joints. Thus, modifications to the joining technique were required. Initially these modifications were based purely on empirical and phenomenological studies, however, detailed mechanistic studies of the underlying joining mechanisms were conducted to aid in selecting these modifications. Mechanisms such as diffusion, solubility and wettability of copper in/on GMPX and 48-2-2 bulk substrates were investigated and compared. A difference in solubility of copper in GMPX and 48-2-2 bulk substrates was attributed to (at least in part) to the observed differences in GMPX and 48-2-2 bonds. The copper solubility, at the bonding temperature, in the 48-2-2 and GMPX alloys was determined to be ˜2 at.% and ˜1

  4. Frequency and causes of failed MODIS cloud property retrievals for liquid phase clouds over global oceans

    Science.gov (United States)

    Cho, Hyoun‐Myoung; Meyer, Kerry; Lebsock, Matthew; Platnick, Steven; Ackerman, Andrew S.; Di Girolamo, Larry; C.‐Labonnote, Laurent; Cornet, Céline; Riedi, Jerome; Holz, Robert E.

    2015-01-01

    Abstract Moderate Resolution Imaging Spectroradiometer (MODIS) retrieves cloud droplet effective radius (r e) and optical thickness (τ) by projecting observed cloud reflectances onto a precomputed look‐up table (LUT). When observations fall outside of the LUT, the retrieval is considered “failed” because no combination of τ and r e within the LUT can explain the observed cloud reflectances. In this study, the frequency and potential causes of failed MODIS retrievals for marine liquid phase (MLP) clouds are analyzed based on 1 year of Aqua MODIS Collection 6 products and collocated CALIOP and CloudSat observations. The retrieval based on the 0.86 µm and 2.1 µm MODIS channel combination has an overall failure rate of about 16% (10% for the 0.86 µm and 3.7 µm combination). The failure rates are lower over stratocumulus regimes and higher over the broken trade wind cumulus regimes. The leading type of failure is the “r e too large” failure accounting for 60%–85% of all failed retrievals. The rest is mostly due to the “r e too small” or τ retrieval failures. Enhanced retrieval failure rates are found when MLP cloud pixels are partially cloudy or have high subpixel inhomogeneity, are located at special Sun‐satellite viewing geometries such as sunglint, large viewing or solar zenith angles, or cloudbow and glory angles, or are subject to cloud masking, cloud overlapping, and/or cloud phase retrieval issues. The majority (more than 84%) of failed retrievals along the CALIPSO track can be attributed to at least one or more of these potential reasons. The collocated CloudSat radar reflectivity observations reveal that the remaining failed retrievals are often precipitating. It remains an open question whether the extremely large r e values observed in these clouds are the consequence of true cloud microphysics or still due to artifacts not included in this study. PMID:27656330

  5. Liquid Phase Catalytic Oxidation of Cumene%异丙苯液相催化氧化

    Institute of Scientific and Technical Information of China (English)

    文飞; 成有为; 郭霞; 王丽军; 李希

    2009-01-01

    在500 mL钛制间歇釜中,以异丙苯为原料,醋酸为溶剂,醋酸钴、醋酸锰和溴化氢为催化剂,空气为氧化剂,考察催化剂浓度和反应温度对产物组成和反应速率的影响,并分析异丙基氧化产物结构.结果表明,比较适宜的反应条件为180℃,催化剂Co和Mn与反应物异丙苯物质的量之比为0.05,该条件下,异丙苯可以完全转化,苯甲酸的收率为95%.异丙苯氧化产物主要为α-甲基苯乙烯、苯乙酮、α-甲基苯乙烯的聚过氧化物以及苯甲酸;整个氧化过程中,α-甲基苯乙烯与氧气作用形成聚过氧化物的反应是影响苯甲酸收率的关键因素;提高反应温度和增加催化剂浓度都能改变口-甲基苯乙烯的聚过氧化物的稳定性,使其开裂并最终转化为苯甲酸.%The effects of catalyst dosage and reaction temperature on the composition of products and reaction rate of liquid phase catalytic oxidation of cumene with oxygen using acetic acid as solvent in the presence of catalysts consisting of cobalt acetate, manganese acetate and bromine compound were investigated in a 500 mL titanium reactor and the structures of the products were analyzed. The results showed that cumene were all conversed and the yield of benzoic acid reached 95% under the appropriate reaction conditions of 180℃ and the molar ratio of Co and Mn to cumene 0.05. α-methylstyrene(MS), acetophenone(AP), α-methylstyrene polyperoxide and benzoic acid(BA) were main products of oxidation of CU. The most important side reaction was copolymerization of α-methylstyrene with oxygen, which had a significant influence on oxidation of cumene. The yield of benzoic acid could be improved by increasing operational temperature and catalyst dosage which could accelerate cleavage of polyperoxide to form benzoic acid.

  6. Bimetallic Au-decorated Pd catalyst for the liquid phase hydrodechlorination of 2,4-dichlorophenol

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Juan [School of the Environment, Donghua University, Shanghai 201620 (China); Chen, Huan, E-mail: hchen404@njust.edu.cn [Key Laboratory of Jiangsu Province for Chemical Pollution Control and Resources Reuse, School of Environmental & Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Chen, Quanyuan; Huang, Zhaolu [School of the Environment, Donghua University, Shanghai 201620 (China)

    2016-11-30

    Graphical abstract: 2,4-Dichlorophenol can be converted to phenol via the catalytic HDC method over Pd-Au/CNTs and the catalytic activity first increased and then decreased with Au content. - Highlights: • Bimetallic catalysts had smaller metal particles and larger number of exposed active site than the monometallic catalysts. • The cationization of Pd particles increased with Au content in the bimetallic catalysts. • The bimetallic catalysts exhibited higher catalytic activities for HDC of 2,4-DCP than the monometallic counterparts. • The concerted pathway for HDC of 2,4-DCP was more predominant with increasing Au content in the bimetallic catalyst. - Abstract: Monometallic and bimetallic Pd-Au catalysts supported on multi-walled carbon nanotubes (CNTs) with varied Au cooperation amounts were prepared using the complexing-reduction method in the presence of tetrahydrofuran (THF). The liquid phase catalytic hydrodechlorination (HDC) of 2,4-dichlorophenol (2,4-DCP) was investigated over these bimetallic catalysts. The catalysts were characterized by N{sub 2} adsorption-desorption isotherms, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and H{sub 2} chemisorption. Characterization results showed that the co-reduction of Pd and Au mainly formed alloy-like structure. The bimetallic catalysts had smaller metal particles and larger numbers of exposed active site than that of monometallic catalysts. In addition, compared with Pd(1.7)/CNTs and Au(0.4)/CNTs, the binding energies of Pd 3d{sub 5/2} shifted to higher positions while that of Au 4f{sub 7/2} had negative shifts in the Pd-Au bimetallic catalysts, which can be ascribed to the electrons transferred from metal Pd to Au and the cationization of Pd particles was enhanced. Accordingly, the bimetallic Pd-Au particles with different Au contents in the catalysts exhibited varied synergistic effects for the catalytic HDC of 2,4-DCP, with Pd(1.8)Au(0.4)/CNTs having the highest

  7. Ionic liquid foam floatation coupled with ionic liquid dispersive liquid-liquid microextraction for the separation and determination of estrogens in water samples by high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Zhang, Rui; Wang, Chuanliu; Yue, Qiaohong; Zhou, Tiecheng; Li, Na; Zhang, Hanqi; Hao, Xiaoke

    2014-11-01

    An ionic liquid foam floatation coupled with ionic liquid dispersive liquid-liquid microextraction method was proposed for the extraction and concentration of 17-α-estradiol, 17-β-estradiol-benzoate, and quinestrol in environmental water samples by high-performance liquid chromatography with fluorescence detection. 1-Hexyl-3-methylimidazolium tetrafluoroborate was applied as foaming agent in the foam flotation process and dispersive solvent in microextraction. The introduction of the ion-pairing and salting-out agent NH4 PF6 was beneficial to the improvement of recoveries for the hydrophobic ionic liquid phase and analytes. Parameters of the proposed method including concentration of 1-hexyl-3-methylimidazolium tetrafluoroborate, flow rate of carrier gas, floatation time, types and concentration of ionic liquids, salt concentration in samples, extraction time, and centrifugation time were evaluated. The recoveries were between 98 and 105% with relative standard deviations lower than 7% for lake water and well water samples. The isolation of the target compounds from the water was found to be efficient, and the enrichment factors ranged from 4445 to 4632. This developing method is free of volatile organic solvents compared with regular extraction. Based on the unique properties of ionic liquids, the application of foam floatation, and dispersive liquid-liquid microextraction was widened.

  8. Selective hydrogenation of 1,3-butadiene in presence of 1-butene under liquid phase conditions with NiPd/Al^sub 2^O3 catalysts

    National Research Council Canada - National Science Library

    Franklin J Méndez; Roger Solano; Yanet Villasana; Julia Guerra; Susana Curbelo; Marcel Inojosa; Claudio Olivera-Fuentes; Joaquín L Brito

    2016-01-01

      The catalytic performance of Al2O3-supported monometallic and bimetallic catalysts in selective hydrogenation of 1,3-butadiene in the presence of 1-butene under liquid phase conditions was studied...

  9. 酮麝香-二甲苯麝香双液相萃取结晶%TWO LIQUID PHASE EXTRACTIVE CRYSTALLIZATION OF MUSK KETONE AND MUSK XYLENE

    Institute of Scientific and Technical Information of China (English)

    曲红梅; 白鹏; 周立山; 杨志才

    2004-01-01

    To evaluate the effect of two liquid phase on the separation of musks mixture, the phase equilibria of musk ketone+musk xylene + dimethyl sulfoxide + heptane system were studied for the first time. The whole and every part of the phase equilibrium for the quaternary system were shown by three-dimensional phase diagrams, the liquid-liquid equilibria, solid-liquid equilibria and solid-liquid-liquid equilibria of the quaternary system were also shown. As a result, the compositions of musks in the equilibrium liquid phases were different from those in the feed, that is, musk ketone was enriched in dimethyl sulfoxide phase while musk xylene was enriched in heptane phase. So these equilibrium liquid phases were useful in separating musk ketone and musk xylene. On the basis of these results, a new process “two liquid phase extractive crystallization” was proposed to separate the eutectics of musk ketone and musk xylene.

  10. A dispersive liquid-liquid micellar microextraction for the determination of pharmaceutical compounds in wastewaters using ultra-high-performace liquid chromatography with DAD detection.

    Science.gov (United States)

    Montesdeoca-Esponda, Sarah; Mahugo-Santana, Cristina; Sosa-Ferrera, Zoraida; Santana-Rodríguez, José Juan

    2015-03-01

    A dispersive liquid-liquid micellar microextraction (DLLMME) method coupled with ultra-high-performance liquid chromatography (UHPLC) using Diode Array Detector (DAD) detector was developed for the analysis of five pharmaceutical compounds of different nature in wastewaters. A micellar solution of a surfactant, polidocanol, as extraction solvent (100 μL) and chloroform as dispersive solvent (200 μL) were used to extract and preconcentrate the target analytes. Samples were heated above critical temperature and the cloudy solution was centrifuged. After removing the chloroform, the reduced volume of surfactant was then injected in the UHPLC system. In order to obtain high extraction efficiency, the parameters affecting the liquid-phase microextraction, such as time and temperature extraction, ionic strength and surfactant and organic solvent volume, were optimized using an experimental design. Under the optimized conditions, this procedure allows enrichment factors of up to 47-fold. The detection limit of the method ranged from 0.1 to 2.0 µg/L for the different pharmaceuticals. Relative standard deviations were <26% for all compounds. The procedure was applied to samples from final effluent collected from wastewater treatment plants in Las Palmas de Gran Canaria (Spain), and two compounds were measured at 67 and 113 µg/L in one of them.

  11. Dynamic and kinetic properties of Al-Li melts

    Science.gov (United States)

    Kiselev, A. I.

    2008-12-01

    The dynamic and kinetic properties of Al-Li melts are calculated. The liquid phase of this system is shown to be characterized by three states with different ion distributions and different degrees of electron localization.

  12. Nanoscale control of the network morphology of high efficiency polymer fullerene solar cells by the use of high material concentration in the liquid phase

    Energy Technology Data Exchange (ETDEWEB)

    Radbeh, R; Parbaile, E; Boucle, J; Di Bin, C; Moliton, A; Ratier, B [XLIM UMR 6172, Universite de Limoges/CNRS, 123 avenue Albert Thomas, F-87060 Limoges Cedex (France); Coudert, V; Rossignol, F, E-mail: bernard.ratier@unilim.fr [Laboratoire de Science des Procedes Ceramiques et de Traitements de Surface (SPCTS), 47 avenue Albert Thomas, F-87065 Limoges (France)

    2010-01-22

    Despite the constant improvement of their power conversion efficiencies, organic solar cells based on an interpenetrating network of a conjugated polymer as donor and fullerene derivatives as acceptor materials still need to be improved for commercial use. In this context, we present a study on the optimization of solar cells based on poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) by varying a specific cell parameter, namely the concentration of the active layer components in the liquid phase before blend film deposition, in order to improve device performance and to better understand the relation between morphology and device operation. Our study shows a significant increase of the short-circuit current, open-circuit voltage and cell efficiency by properly choosing the formulation of the initial blend before film deposition. We demonstrate that the active layer morphology, which is strongly dependent on the initial material concentrations and the processing conditions, can greatly impact the electronic characteristics of the device, especially regarding charge recombination dynamics at the donor-acceptor interface. Our optimized P3HT:PCBM device exhibits both slow recombination and high photocurrent generation associated with an overall power conversion efficiency of 4.25% under 100 mW cm{sup -2} illumination (AM1.5G).

  13. Nanoscale control of the network morphology of high efficiency polymer fullerene solar cells by the use of high material concentration in the liquid phase.

    Science.gov (United States)

    Radbeh, R; Parbaile, E; Bouclé, J; Di Bin, C; Moliton, A; Coudert, V; Rossignol, F; Ratier, B

    2010-01-22

    Despite the constant improvement of their power conversion efficiencies, organic solar cells based on an interpenetrating network of a conjugated polymer as donor and fullerene derivatives as acceptor materials still need to be improved for commercial use. In this context, we present a study on the optimization of solar cells based on poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) by varying a specific cell parameter, namely the concentration of the active layer components in the liquid phase before blend film deposition, in order to improve device performance and to better understand the relation between morphology and device operation. Our study shows a significant increase of the short-circuit current, open-circuit voltage and cell efficiency by properly choosing the formulation of the initial blend before film deposition. We demonstrate that the active layer morphology, which is strongly dependent on the initial material concentrations and the processing conditions, can greatly impact the electronic characteristics of the device, especially regarding charge recombination dynamics at the donor-acceptor interface. Our optimized P3HT:PCBM device exhibits both slow recombination and high photocurrent generation associated with an overall power conversion efficiency of 4.25% under 100 mW cm(-2) illumination (AM1.5G).

  14. Elucidating the Weak Protein-Protein Interaction Mechanisms behind the Liquid-Liquid Phase Separation of a mAb Solution by Different Types of Additives.

    Science.gov (United States)

    Wu, Guoliang; Wang Co-First, Shujing; Tian, Zhou; Zhang, Ning; Sheng, Han; Dai, Weiguo; Qian, Feng

    2017-07-25

    Liquid-liquid phase separation (LLPS) has long been observed during the physical stability investigation of therapeutic protein formulations. The buffer conditions and the presence of various excipients are thought to play important roles in the formulation development of monoclonal antibodies (mAbs). In this study, the effects of several small-molecule excipients (histidine, alanine, glycine, sodium phosphate, sodium chloride, sorbitol and sucrose) with diverse physical-chemical properties on LLPS of a model IgG1 (JM2) solutions were investigated by multiple techniques, including UV-vis spectroscopy, circular dichroism, differential scanning calorimetry/fluorimetry, size exclusion chromatography and dynamic light scattering. The LLPS of JM2 was confirmed to be a thermodynamic equilibrium process with no structural changes or irreversible aggregation of proteins. Phase diagrams of various JM2 formulations were constructed, suggesting that the phase behavior of JM2 was dependent on the solution pH, ionic strength and the presence of other excipients such as glycine, alanine, sorbitol and sucrose. Furthermore, we demonstrated that for this mAb, the interaction parameter (kD) determined at low protein concentration appeared to be a good predictor for the occurrence of LLPS at high concentration. Copyright © 2017. Published by Elsevier B.V.

  15. Nanoscale control of the network morphology of high efficiency polymer fullerene solar cells by the use of high material concentration in the liquid phase

    Science.gov (United States)

    Radbeh, R.; Parbaile, E.; Bouclé, J.; Di Bin, C.; Moliton, A.; Coudert, V.; Rossignol, F.; Ratier, B.

    2010-01-01

    Despite the constant improvement of their power conversion efficiencies, organic solar cells based on an interpenetrating network of a conjugated polymer as donor and fullerene derivatives as acceptor materials still need to be improved for commercial use. In this context, we present a study on the optimization of solar cells based on poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) by varying a specific cell parameter, namely the concentration of the active layer components in the liquid phase before blend film deposition, in order to improve device performance and to better understand the relation between morphology and device operation. Our study shows a significant increase of the short-circuit current, open-circuit voltage and cell efficiency by properly choosing the formulation of the initial blend before film deposition. We demonstrate that the active layer morphology, which is strongly dependent on the initial material concentrations and the processing conditions, can greatly impact the electronic characteristics of the device, especially regarding charge recombination dynamics at the donor-acceptor interface. Our optimized P3HT:PCBM device exhibits both slow recombination and high photocurrent generation associated with an overall power conversion efficiency of 4.25% under 100 mW cm-2 illumination (AM1.5G).

  16. Determination of perfluorinated compounds (PFCs) in solid and liquid phase river water samples in Chao Phraya River, Thailand.

    Science.gov (United States)

    Kunacheva, Chinagarn; Tanaka, Shuhei; Fujii, Shigeo; Boontanon, Suwanna Kitpati; Musirat, Chanatip; Wongwattana, Thana

    2011-01-01

    Perfluorinated compounds (PFCs), especially perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), are fully fluorinated organic compounds, which have been used in many industrial applications. These chemicals have contaminated surface water all over the world even in developing countries like Thailand. The previous study showed the contamination in Chao Phraya River in 2006 and 2007. The purposes of this field study were to determine the solid and liquid phase of PFCs contamination in Chao Phraya River and to compare the changes of PFC concentration in 2008. Surveys were conducted in the lower reach of Chao Phraya River in the industrialized area. A solid phase extraction (SPE) coupled with HPLC-ESI-MS/MS were used for the analysis for ten PFCs. Ten PFCs were analyzed to identify the contamination in both solid and liquid phases. PFCs were detected in both the solid and liquid phase in every sample. PFOA was the most dominant PFC while PFPA and PFOS were also highly detected in most samples. The average loadings of PFPA, PFOA and PFOS in Chao Phraya River were 94.3, 284.6 and 93.4 g/d, respectively. PFOS concentrations did not show differences between 2006 and 2008. However, PFOA concentrations were higher in 2008/5/26, while comparing other samplings. The ratio of solid:liquid PFPA (2.1:1.0) [(ng/g)/(ng/L)] was lower than PFOA (13.9:1.0) [(ng/g)/(ng/L)] and PFOS (17.6:1.0) [(ng/g)/(ng/L)]. The shorter chain (more hydrophilic) PFC was better to dissolve in water rather than adsorb onto suspended solids. PFOS also showed more potential to attach in the suspended solids than PFOA.

  17. A novel extraction technique based on carbon nanotubes reinforced hollow fiber solid/liquid microextraction for the measurement of piroxicam and diclofenac combined with high performance liquid chromatography.

    Science.gov (United States)

    Song, Xin-Yue; Shi, Yan-Ping; Chen, Juan

    2012-10-15

    A novel design of carbon nanotubes reinforced hollow fiber solid/liquid phase microextraction (CNTs-HF-SLPME) was developed to determine piroxicam and diclofenac in different real water samples. Functionalized multi-walled carbon nanotubes (MWCNTs) were held in the pores of hollow fiber with sol-gel technology. The pores and lumen of carbon nanotubes reinforced hollow fiber were subsequently filled with a μL volume of organic solvent (1-octanol), and then the whole assembly was used for the extraction of the target analytes in direct immersion sampling mode. The target analytes were extracted from the sample by two extractants, one of which is organic solvent placed inside the pores and lumen of hollow fiber and the other one is CNTs held in the pores of hollow fiber. After extraction, the analytes were desorbed in acetonitrile and analyzed using high performance liquid chromatography. This novel extraction mode showed more excellent extraction performance in comparison with conventional hollow fiber liquid microextraction (without adding CNTs) and carbon nanotubes reinforced hollow fiber solid microextraction (CNTs held in the pores of hollow fiber, but no organic solvents placed inside the lumen of hollow fiber) under the respective optimum conditions. This method provided 47- and 184-fold enrichment factors for piroxicam and diclofenac, respectively, good inter-fiber repeatability and batch-to-batch reproducibility. Linearity was observed in the range of 20-960 μg L(-1) for piroxicam, and 10-2560 μg L(-1) for diclofenac, with correlation coefficients of 0.9985 and 0.9989, respectively. The limits of detection were 4.58 μg L(-1) for piroxicam and 0.40 μg L(-1) for diclofenac.

  18. Determination of hormones in milk by hollow fiber-based stirring extraction bar liquid-liquid microextraction gas chromatography mass spectrometry.

    Science.gov (United States)

    Xu, Xu; Liang, Fanghui; Shi, Jiayuan; Zhao, Xin; Liu, Zhuang; Wu, Lijie; Song, Ying; Zhang, Hanqi; Wang, Ziming

    2013-08-06

    The hollow fiber-based stirring extraction bar liquid-liquid microextraction was applied to the extraction of hormones, including 17-α-ethinylestradiol, 17-α-estradiol, estriol, 17-β-estradiol, estrone, 17-α-hydroxyprogesterone, medroxyprogesterone, progesterone and norethisterone acetate, in milk. The present method has the advantages of both hollow fiber-liquid phase microextraction and stirring bar sorptive extraction. The stirring extraction bar was used as both the stirring bar of microextraction, and extractor of the analytes, which can make extraction, clean-up and concentration be carried out in one step. When the extraction was completed, the stirring extraction bar was easy isolated from the extraction system with the magnet. Several experimental parameters, including the type of extraction solvent, the number of hollow stirring extraction bar, extraction time, stirring speed, ionic strength, and desorption conditions were investigated and optimized. The analytes in the extract were derived and determined by gas chromatography mass spectrometry. Under optimal experimental conditions, good linearity was observed in the range of 0.20-20.00ng mL(-1). The limits of detection and quantification were in the range of 0.02-0.06ng mL(-1) and 0.07-0.19ng mL(-1), respectively. The present method was applied to the analysis of milk samples, and the recoveries of analytes were in the range of 93.6-104.6% with the relative standard deviations ranging from 1.6% to 6.2% (n=5). The results showed that the present method was a rapid and feasible method for the determination of hormones in milk samples.

  19. Sol-gel methyl coating in capillary microextraction hyphenated on-line with high-performance liquid chromatography Counterintuitive extraction behavior for polar analytes.

    Science.gov (United States)

    Segro, Scott S; Malik, Abdul

    2008-07-18

    A sol-gel coating with anchored methyl groups was developed for capillary microextraction hyphenated on-line with high-performance liquid chromatography (HPLC). This was accomplished by using methyltrimethoxysilane as the sol-gel precursor. The methyl group on the sol-gel precursor ultimately turned into a pendant group on the created sol-gel coating and was primarily responsible for the extraction of nonpolar analytes. A 40-cm segment of 0.25mm I.D. fused silica capillary containing the sol-gel methyl coating on the inner surface was installed as a sampling loop in an HPLC injection port. The analytes were extracted by the coating when an aqueous sample containing the analytes was passed through this capillary. The extracted analytes were then transferred to the HPLC column using isocratic elution with an acetonitrile/water mobile phase. This capillary demonstrated excellent extraction capability for polycyclic aromatic hydrocarbons and ketones. Unexpectedly, this coating also provided good extraction for polar analytes, including aromatic phenols, alcohols, and amines. Considering the fact that the methyl group is nonpolar in nature, such an extraction behavior of sol-gel methyl coating toward polar analytes is counterintuitive. Thus, sol-gel sorbents with short alkyl side chains have the potential to offer a polymer-free alternative to traditional sol-gel capillary microextraction (CME) media commonly prepared with the use of polymers in the sol solution. Elimination of polymers from the sol-gel coating solution is conducive to improving thermal stability and solvent tolerance of the created sol-gel extracting phase. This also makes the preparation of sol-gel coatings facile and cost-effective. Possessing excellent solvent stability, such sol-gel coatings offer the opportunity for effective on-line hyphenation of capillary microextraction with HPLC and other liquid-phase separation techniques that employ organo-aqueous mobile phases.

  20. Comparative study of {sup 137}Cs partitioning between solid and liquid phases in Lakes Constance, Lugano and Vorsee

    Energy Technology Data Exchange (ETDEWEB)

    Konoplev, A. E-mail: konoplev@obninsk.com; Kaminski, S.; Klemt, E.; Konopleva, I.; Miller, R.; Zibold, G

    2002-07-01

    The methodology for estimating radiocaesium distribution between solid and liquid phases in lakes is applied for three prealpine lakes: Lake Constance (Germany), Lake Lugano (Switzerland) and Lake Vorsee (Germany). It is based on use of the exchangeable distribution coefficient and application of the exchangeable radiocaesium interception potential (RIP{sup ex}). The methodology was tested against experimental data. Good agreement was found between estimated and measured {sup 137}Cs concentrations in Lake Constance and Lake Lugano, whereas for Lake Vorsee a discrepancy was found. Bottom sediments in Lake Vorsee are composed mainly of organic material and probably cannot be described in terms of the specific sorption characteristics attributed to illitic clay minerals.

  1. Comparative study of 137Cs partitioning between solid and liquid phases in Lakes Constance, Lugano and Vorsee.

    Science.gov (United States)

    Konoplev, A; Kaminski, S; Klemt, E; Konopleva, I; Miller, R; Zibold, G

    2002-01-01

    The methodology for estimating radiocaesium distribution between solid and liquid phases in lakes is applied for three prealpine lakes: Lake Constance (Germany), Lake Lugano (Switzerland) and Lake Vorsee (Germany). It is based on use of the exchangeable distribution coefficient and application of the exchangeable radiocaesium interception potential (RIPex). The methodology was tested against experimental data. Good agreement was found between estimated and measured 137Cs concentrations in Lake Constance and Lake Lugano, whereas for Lake Vorsee a discrepancy was found. Bottom sediments in Lake Vorsee are composed mainly of organic material and probably cannot be described in terms of the specific sorption characteristics attributed to illitic clay minerals.

  2. Liquid-phase plasma synthesis of silicon quantum dots embedded in carbon matrix for lithium battery anodes

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Ying [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou (China); College of Chemistry and Chemical Engineering, Bohai University, Jinzhou 121000 (China); Yu, Hang; Li, Haitao; Ming, Hai; Pan, Keming; Huang, Hui [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou (China); Liu, Yang, E-mail: yangl@suda.edu.cn [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou (China); Kang, Zhenhui, E-mail: zhkang@suda.edu.cn [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou (China)

    2013-10-15

    Graphical abstract: - Highlights: • Silicon quantum dots embedded in carbon matrix (SiQDs/C) were fabricated. • SiQDs/C exhibits excellent battery performance as anode materials with high specific capacity. • The good performance was attributed to the marriage of small sized SiQDs and carbon. - Abstract: Silicon quantum dots embedded in carbon matrix (SiQDs/C) nanocomposites were prepared by a novel liquid-phase plasma assisted synthetic process. The SiQDs/C nanocomposites were demonstrated to show high specific capacity, good cycling life and high coulmbic efficiency as anode materials for lithium-ion battery.

  3. Interface evolution of TiAl/Ti6242 transient liquid phase joint using Ti, Cu foils as insert metals

    Institute of Scientific and Technical Information of China (English)

    DUAN Hui-ping; K. H. Bohm; V. Ventzke; M. Kocak

    2005-01-01

    The interface evolution of TiAl/Ti6242 joint produced by transient liquid phase(TLP) bonding with Ti,Cu foils as insert metals was investigated. The results show that the surface oxide layer on TiAl plays a very imporer on the surface of TiAl. The diffusion behavior of Cu atoms in TiAl is strongly controlled by the vacancies beneath the surface of TiAl. Based on the interface diffusion and interface wettability, a mechanism for the effect of bonding pressure, bonding temperature, holding time and stacking sequence of the insert foils on the joint formation process were proposed.

  4. 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.

  5. Cyclic PNA-based compound directed against HIV-1 TAR RNA: modelling, liquid-phase synthesis and TAR binding.

    Science.gov (United States)

    Depecker, Geoffrey; Patino, Nadia; Di Giorgio, Christophe; Terreux, Raphael; Cabrol-Bass, Daniel; Bailly, Christian; Aubertin, Anne-Marie; Condom, Roger

    2004-01-07

    A cyclic molecule including a hexameric PNA sequence has been designed and synthesized in order to target the TAR RNA loop of HIV-1 through the formation of a "kissing complex". For comparison, its linear analogue has also been investigated. The synthesis of the cyclic and linear PNA has been accomplished following a liquid-phase strategy using mixed PNA and fully N-protected (aminoethylglycinamide) fragments. The interactions of this cyclic PNA and its linear analogue with TAR RNA have been studied and the results indicate clearly that no interaction occurs between the cyclic antisense PNA and TAR RNA, whereas a tenuous interaction has been detected with its linear PNA analogue.

  6. Solid-liquid phase transitions in 3D systems with the inverse-power and Yukawa potentials

    Science.gov (United States)

    Vaulina, O. S.; Koss, X. G.

    2016-03-01

    The melting of face-centered cubic (fcc) and body-centered cubic (bcc) crystal lattices was studied analytically and numerically for the systems of particles interacting via the inverse-power-law and Yukawa potentials. New approach is proposed for determination of the solid-liquid phase transitions in these systems. The suggested approach takes into account a nonlinearity (anharmonicity) of pair interaction forces and allows to correctly predict the conditions of melting of the systems with various isotropic pair interaction potentials. The obtained results are compared with the existing theoretical and numerical data.

  7. Solid and liquid phase equilibria and solid-hydrate formation in binary mixtures of water with amines

    Institute of Scientific and Technical Information of China (English)

    车冠全; 彭文烈; 黄良恩; 古喜兰; 车飙

    1997-01-01

    Solid and liquid phase diagrams have been constructed for {water+triethylamine,or+N,N-dimethylformamide(DMF) or+N,N-dimethlacetamide (DMA)} Solid-hydrates form with the empirical formulae N(C2H5)3 3H2O,DMF 3H2O,DMF 2H2O,DMA 3H2O and (DMA)2 3H2O.All are congruently melting except the first which melts incongruently.The solid-hydrate formation is attributed to hydrogen bond.The results are compared with the references

  8. 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...

  9. Interface morphology studies of liquid phase epitaxy grown HgCdTe films by atomic force microscopy

    Science.gov (United States)

    Azoulay, M.; George, M. A.; Burger, A.; Collins, W. E.; Silberman, E.

    1994-04-01

    In this paper we report an investigation of the morphology of the interfaces of liquid phase epitaxy (LPE) grown HgCdTe thin films on CdTe and CdZnTe substrates by atomic force microscopy (AFM) on freshly cleaved (110) crystallographic planes. An empirical observation which may be linked to lattice mismatch was indicated by an angle between the cleavage steps of the substrate to those of the film. The precipitates with size ranging from 5 nm to 20 nm were found to be most apparent near the interface.

  10. Combining drop-to-drop solvent microextraction with gas chromatography/mass spectrometry using electronic ionization and self-ion/molecule reaction method to determine methoxyacetophenone isomers in one drop of water.

    Science.gov (United States)

    Wu, Hui-Fen; Yen, Jyh-Hao; Chin, Chen-Che

    2006-03-01

    A novel analytical technique termed drop-to-drop solvent microextraction (DDSME) was developed to determine three methoxyacetophenone isomers in one drop of water, which were then detected by gas chromatography/mass spectrometry using electronic ionization mass spectrometry for quantification analysis and self-ion/molecule reaction/tandem mass spectrometry for isomer differentiation. The best optimum parameters for the DDSME technique were as follows: extraction time, 5 min; using toluene as the extraction solvent; volume of extraction solvent, 0.5 microL and no salt addition. The advantages of this method are rapidity, convenience, ease of operation, simplicity of the device, and extremely little solvent and sample consumption. The limit of detection (LOD) for this technique was 1 ng/mL. The relative standard deviation was less than 2.6% (n = 5). The linear range of the calibration curve of DDSME is from 0.01 to 5 microg/mL with correlation coefficient (r2) of >0.954. In the comparison of the LOD of DDSME with other sample pretreatment methods including liquid/liquid extraction (LLE), single-drop microextraction (SDME), solid-phase microextraction (SPME), and liquid-phase microextraction (LPME) using a dual gauge microsyringe with hollow fiber methods, this method shows much better in sensitivity than the LLE (25 ng/mL) and it is compatible with SDME (0.5 ng/mL), SPME (0.5 ng/mL), and LPME using a dual gauge microsyringe with a hollow fiber (1 ng/mL). However, DDSME was more convenient than the LPME using a dual gauge microsyringe with a hollow fiber method and much lower cost than the SPME technique.

  11. Novel Gas-assisted Three-liquid-phase Extraction System for Simultaneous Separation and Concentration of Anthraquinones in Herbal Extract

    Institute of Scientific and Technical Information of China (English)

    Xingfu Yang; Xiangfeng Liang; Liangrong Yang; Feng Pan; Fuli Deng; Huizhou Liu

    2014-01-01

    abstract Gas-assisted three-liquid-phase extraction (GATE), which has the advantages of both three-liquid-phase extrac-tion and solvent sublation, is a novel separation technique for separation and concentration of two organic com-pounds into different phases in one step. This highly effective and economically applicable method has been developed for separating emodin and rhein from herbal extract. In a GATE system composed of butyl acetate/PEG4000/ammonium sulfate aqueous solution, influence of various parameters including gas flow rate, flotation time, salt concentration, initial volume of PEG and butyl acetate was investigated. Within 50 min of 30 ml·min-1 nitrogen flow, removal ratio of emodin and rhein from aqueous phase could be over 99%and 97%, respectively. Mass fraction of emodin in the BA phase and rhein in the PEG phase could reach 97%and 95%, respectively. It is demonstrated that gas bubbling is effective for partitioning of emodin and rhein into butyl acetate and PEG phase respectively, and dispersed PEG and butyl acetate could be captured from the aqueous solution. Experi-mental results show that GATE could be an effective and economical technology for concentration and separation of co-existed products in medicinal plants.

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

    Science.gov (United States)

    Lee, Heon; Park, Sung Hoon; Park, Young-Kwon; Kim, Byung Hoon; Kim, Sun-Jae; Jung, Sang-Chul

    2013-09-16

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

  13. Synthesis of p-Hydroxybenzaldehyde by Liquid-phase Catalytic Oxidation of p-Cresol over PVDF Modified Cobalt Pyrophosphate

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yi-bo; WANG De-qiang; MIAO Zhen-zhen; PAN Xi-qiang; ZHANG Zhen-dong; YANG Xiang-guang

    2013-01-01

    The influence of the wettability of a catalyst on the performance of the liquid phase oxidation of p-cresol was investigated.It was found that the surface hydrophobicity of a catalyst,which can be changed by modification with various loadings of polyvinylidene fluoride(PVDF),has a promotion effect on the catalytic performance.At the same time,the reaction parameters such as oxygen pressure,molar ratio of NaOH to p-cresol,reaction temperature and time on the catalytic performance in the liquid-phase oxidation of p-cresol were optimized.As a result,10%(mass fraction) PVDF modified cobalt pyrophosphate gave the highest conversion of 94.2% of p-cresol with a selectivity of 94.4% for p-hydroxybenzaldehyde at 348 K and a molar ratio of 4:1 of NaOH/p-cresol and an oxygen pressure of 1.0 MPa for 3 h.

  14. Measurements of liquid phase residence time distributions in a pilot-scale continuous leaching reactor using radiotracer technique.

    Science.gov (United States)

    Pant, H J; Sharma, V K; Shenoy, K T; Sreenivas, T

    2015-03-01

    An alkaline based continuous leaching process is commonly used for extraction of uranium from uranium ore. The reactor in which the leaching process is carried out is called a continuous leaching reactor (CLR) and is expected to behave as a continuously stirred tank reactor (CSTR) for the liquid phase. A pilot-scale CLR used in a Technology Demonstration Pilot Plant (TDPP) was designed, installed and operated; and thus needed to be tested for its hydrodynamic behavior. A radiotracer investigation was carried out in the CLR for measurement of residence time distribution (RTD) of liquid phase with specific objectives to characterize the flow behavior of the reactor and validate its design. Bromine-82 as ammonium bromide was used as a radiotracer and about 40-60MBq activity was used in each run. The measured RTD curves were treated and mean residence times were determined and simulated using a tanks-in-series model. The result of simulation indicated no flow abnormality and the reactor behaved as an ideal CSTR for the range of the operating conditions used in the investigation.

  15. Immunoassay of paralytic shellfish toxins by moving magnetic particles in a stationary liquid-phase lab-on-a-chip.

    Science.gov (United States)

    Kim, Myoung-Ho; Choi, Suk-Jung

    2015-04-15

    In this study, we devised a stationary liquid-phase lab-on-a-chip (SLP LOC), which was operated by moving solid-phase magnetic particles in the stationary liquid phase. The SLP LOC consisted of a sample chamber to which a sample and reactants were added, a detection chamber containing enzyme substrate solution, and a narrow channel connecting the two chambers and filled with buffer. As a model system, competitive immunoassays of saxitoxin (STX), a paralytic shellfish toxin, were conducted in the SLP LOC using protein G-coupled magnetic particles (G-MPs) as the solid phase. Anti-STX antibodies, STX-horseradish peroxidase conjugate, G-MPs, and a STX sample were added to the sample chamber and reacted by shaking. While liquids were in the stationary state, G-MPs were transported from the sample chamber to the detection chamber by moving a magnet below the LOC. After incubation to allow the enzymatic reaction to occur, the absorbance of the detection chamber solution was found to be reciprocally related to the STX concentration of the sample. Thus, the SLP LOC may represent a novel, simple format for point-of-care testing applications of enzyme-linked immunosorbent assays by eliminating complicated liquid handling steps.

  16. Formation process,microstructure and mechanical property of transient liquid phase bonded aluminium-based metal matrix composite joint

    Institute of Scientific and Technical Information of China (English)

    孙大谦; 刘卫红; 贾树盛; 邱小明

    2004-01-01

    The formation process, microstructure and mechanical properties of transient liquid phase (TLP) bonded aluminium-based metal matrix composite (MMC) joint with copper interlayer were investigated. The formation process of the TLP joint comprises a number of stages: plastic deformation and solid diffusion (stage 1), dissolution of interlayer and base metal (stage 2), isothermal solidification (stage 3) and homogenization (stage 4). The microstructure of the joint depends on the joint formation process (distinct stages). The plastic deformation and solid diffusion in stage 1 favoure the intimate contact at interfaces and liquid layer formation. The microstructure of joint consists of aluminium solid solution, alumina particle, Al2Cu and MgAl2O4 compounds in stage 2. The most pronounced feature of joint microstructure in stage 3 is the alumina particle segregation in the center of the joint. The increase of joint shear strength with increasing bonding temperature is mainly attributed to improving the fluidity and wettability of liquid phase and decreasing the amount of Al2Cu brittle phase in the joint. The principal reason of higher bonding temperature (>600 ℃) resulting in lowering obviously the joint shear strength is the widening of alumina particle segregation region that acts as a preferential site for failure. The increase of joint shear strength with increasing holding time is mainly associated with decreasing the amount of Al2 Cu brittle phase and promoting homogenization of joint.

  17. Total enthalpy-based lattice Boltzmann method with adaptive mesh refinement for solid-liquid phase change

    Science.gov (United States)

    Huang, Rongzong; Wu, Huiying

    2016-06-01

    A total enthalpy-based lattice Boltzmann (LB) method with adaptive mesh refinement (AMR) is developed in this paper to efficiently simulate solid-liquid phase change problem where variables vary significantly near the phase interface and thus finer grid is required. For the total enthalpy-based LB method, the velocity field is solved by an incompressible LB model with multiple-relaxation-time (MRT) collision scheme, and the temperature field is solved by a total enthalpy-based MRT LB model with the phase interface effects considered and the deviation term eliminated. With a kinetic assumption that the density distribution function for solid phase is at equilibrium state, a volumetric LB scheme is proposed to accurately realize the nonslip velocity condition on the diffusive phase interface and in the solid phase. As compared with the previous schemes, this scheme can avoid nonphysical flow in the solid phase. As for the AMR approach, it is developed based on multiblock grids. An indicator function is introduced to control the adaptive generation of multiblock grids, which can guarantee the existence of overlap area between adjacent blocks for information exchange. Since MRT collision schemes are used, the information exchange is directly carried out in the moment space. Numerical tests are firstly performed to validate the strict satisfaction of the nonslip velocity condition, and then melting problems in a square cavity with different Prandtl numbers and Rayleigh numbers are simulated, which demonstrate that the present method can handle solid-liquid phase change problem with high efficiency and accuracy.

  18. Tunable UV-visible absorption of SnS2 layered quantum dots produced by liquid phase exfoliation.

    Science.gov (United States)

    Fu, Xiao; Ilanchezhiyan, P; Mohan Kumar, G; Cho, Hak Dong; Zhang, Lei; Chan, A Sattar; Lee, Dong J; Panin, Gennady N; Kang, Tae Won

    2017-02-02

    4H-SnS2 layered crystals synthesized by a hydrothermal method were used to obtain via liquid phase exfoliation quantum dots (QDs), consisting of a single layer (SLQDs) or multiple layers (MLQDs). Systematic downshift of the peaks in the Raman spectra of crystals with a decrease in size was observed. The bandgap of layered QDs, estimated by UV-visible absorption spectroscopy and the tunneling current measurements using graphene probes, increases from 2.25 eV to 3.50 eV with decreasing size. 2-4 nm SLQDs, which are transparent in the visible region, show selective absorption and photosensitivity at wavelengths in the ultraviolet region of the spectrum while larger MLQDs (5-90 nm) exhibit a broad band absorption in the visible spectral region and the photoresponse under white light. The results show that the layered quantum dots obtained by liquid phase exfoliation exhibit well-controlled and regulated bandgap absorption in a wide tunable wavelength range. These novel layered quantum dots prepared using an inexpensive method of exfoliation and deposition from solution onto various substrates at room temperature can be used to create highly efficient visible-blind ultraviolet photodetectors and multiple bandgap solar cells.

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

    Science.gov (United States)

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

    2012-12-21

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

  20. Structure and property of metal melt Ⅰ:The number of residual bonds after solid-liquid phase changes

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Based on the mechanism of metal solid-liquid phase change and the theory of liquid metal’s micro-inhomogeneity,a physical model is established between latent heats of fusion and vaporization and the numbers of residual bonds and short-range ordered atoms at the melting point inside a metal melt.Meanwhile,the mathematical derivation and proof are also offered.This model produces the numbers of residual bonds and short-range ordered atoms after the solid-liquid phase change only by using basic parameters and thermophysical properties of the crystal structure.Therefore,it presents a more effective way to analyze the melt’s structural information.By using this model,this study calculates the numbers of residual bonds and short-range ordered atoms in Al and Ni melts.The calculated results are consistent with the experimental results.Simultaneously,this study discusses the atomic number’s influence on the numbers of residual bonds and short-range ordered atoms in the melts within the first(ⅠA) and second main group(ⅡA) elements.